1,155 results
Search Results
2. Between People and Paper: Inhabiting Experiment in a Journal Club.
- Author
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Klein, Sarah
- Subjects
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SCIENCE journalism , *COMMUNICATION infrastructure , *COMMUNITIES , *COOPERATIVE research , *INFORMATION services , *ELECTRONIC journals - Abstract
In 2015, the Open Science Collaboration reported in the journal Science that a disturbingly large proportion of psychological studies cannot be replicated (Open Science Collaboration, 2015). The ensuing 'reproducibility crisis' became a lightning rod for contesting what counts as legitimate research, and for negotiating the relationship between communication infrastructures and research practice. In the psychological and cognitive sciences, the Open Science community has advocated widespread reforms to incentivize transparency, encourage replication, and detect and discourage questionable research practices. The model of 'openness' underlying mainstream Open Science centers on sharing information to increase science's self-correcting capacity. Against the backdrop of broad-scale transformations in Open Science, this case study depicts how scientists read. By examining the activity of a group of researchers 'virtually witnessing' an experiment together, this study reveals reading as a non-trivial process that matters for how research is apprehended and for how science is moved through time and space. The case complicates a disembodied, information-centric 'openness' pursued by mainstream Open Science reforms and advocates integrating situated and embodied resources into methods reforms, beginning with practices of reading. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. Idea paper: Monitoring and databasing nonnative species to manage establishment debt in aquatic ecosystems.
- Subjects
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INTRODUCED species , *DEBT , *PET industry , *ENVIRONMENTAL databases , *ECOSYSTEMS , *BIOLOGICAL invasions - Abstract
In the era of globalization, biological invasions are one of the most serious social issues. Thus, managing its impact is an urgent task. It is essential to control nonnative species before they become established. However, it is insufficient to address establishment debt, which occurs when a nonnative species has been introduced into an area but has not yet been established in the wild. In particular, unintentionally introduced or contaminated organisms of the aquatic ornamental pet trade are referred to as "hitchhikers" and have not received much attention in the context of establishment debt. To understand the nature of establishment debt, including that of aquatic hitchhikers, I propose the monitoring of nonnative species inhabiting artificial isolated waters, such as indoor aquariums, and the construction of a database using environmental DNA metabarcoding. This idea would be an effective nonregulatory management approach when implemented broadly, at the country level. Furthermore, implementation of this strategy in combination with border biosecurity and field monitoring may promote accurate prioritization, rapid species identification, and effective invasion pathway assessment. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Idea paper: Extended benefits of pollinator‐mediated microbial dispersal among flowers.
- Author
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Takeda, Kazuya and Sakai, Shoko
- Subjects
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POLLINATORS , *PLANT surfaces , *FLOWERS , *POLLINATION , *MICROBIAL communities , *HOST plants , *PLANT cells & tissues - Abstract
Since the production of large and conspicuous flowers can be costly, self‐pollinated or asexually reproducing plants are expected to lose characters for pollinator attraction. However, some plants still produce conspicuous flowers despite not relying on pollinators for fertilization, suggesting overlooked benefits of receiving flower visitors. Here, we present visitor‐mediated microbial dispersal as a potential benefit of receiving flower visitors. Recent studies revealed that diverse microbes inhabit plant surfaces or plant tissues and that these microbes substantially benefit host plants. Animal flower visitors disperse these microbes. Since some microbes can migrate to seeds, the enhanced dispersal via visitors can modulate microbial communities of the next generations. Microbial dispersal via flower visitors may improve plant fitness via increased opportunities to receive microbes mutualistic for seeds and higher variances in seed microbial communities that function as "bet‐hedging." We can test this hypothesis by comparing microbial communities and the performance of seeds from experimentally visitor‐excluded flowers and naturally animal‐visited control flowers. Further experiments with sterilization or microbe inoculation may confirm the contribution of specific taxa or microbial community structures to the observed effects on seed performances. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
5. Idea paper: Effects of gonad type and body mass on the time required for sex change in fishes.
- Author
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Tokunaga, Soma, Kadota, Tatsuru, Watanabe, Yuuki Y., Kuwamura, Tetsuo, and Kawabata, Yuuki
- Subjects
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GONADS , *SEX change in animals , *GENDER transition , *CHRONOBIOLOGY - Abstract
Sex change is a well‐known phenomenon in teleost fishes, and it takes several days to a few months depending on the species and direction of sex change. However, the underlying factors influencing the time required for sex change (TS) remain unclear. Given that the time for producing a new gonad largely determines TS, the gonad type (i.e., whether fish retain the gonad of opposite sex or not [delimited or non‐delimited]) and metabolic rate may affect TS. This study sought to test two hypotheses: (1) the delimited gonad shortens TS and (2) TS scales with mass0.1−0.2, because the metabolic scaling exponent (β) in fishes is 0.8–0.9 and biological times scale with mass1−β in general. We compiled data on TS for 12 female‐to‐male and 14 male‐to‐female sex‐changing species from the literature. Results of individual examinations of the effects of gonad type and mass were consistent with our hypotheses. However, upon simultaneous examination of the effects of gonad type and mass, these effects became unclear because of their strong multicollinearity. The compiled data for delimited and non‐delimited gonads were biased toward the smaller and larger species, respectively, precluding us from being able to statistically distinguish between these effects. Small species with non‐delimited gonads and large species with delimited gonads exist; however, their TS has not been measured with high temporal resolution thus far. Therefore, additional experiments on these species are required to statistically distinguish between, as well as to better understand, the effects of gonad type and mass on TS. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
6. Idea Paper: Tracking the distribution of accretive reef communities across the Kuroshio region.
- Author
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Denis, Vianney, Fan, Tung‐Yung, Hsiao, Wanchien Victoria, Hwang, Sung‐Jin, Lin, Yuting Vicky, and Nozawa, Yoko
- Subjects
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REEFS , *COMMUNITIES , *CORAL reef ecology , *OCEAN , *CORAL reefs & islands ,KUROSHIO - Abstract
In line with contemporary changes in oceanic conditions, reef communities could be declining at the equator and expanding polewards, having previously happened in the past. Yet, some tropical organisms are now decimated at their distributional cores and observed beyond their inferred range limits. However, it remains unclear if this is happening at the community scale, especially due to the challenges of collecting quantitative and comparable data across latitudes. Here, we propose that monitoring sentinel plots via photogrammetry could help to assess abiding changes in benthic communities and trajectories of reef‐building populations across the Kuroshio region. We think that as oceans are becoming warmer, accretive reef communities may shift their distribution northwards which may be primarily due to a change in the relative biomass‐abundance of resident taxa. Consistent trends among latitudes will resolve the possibility of contraction or expansion of accretive reef communities, providing further insight into the variety of responses and dynamics observed across latitudes in the context of the Anthropocene. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
7. Experimental Study of Hot-Sphere Anemometer Response in Stratospheric Environment.
- Author
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Li, Xiyuan, Yang, Xiaoning, Shen, Xiaobin, Lin, Guiping, Tao, Dongxing, and Wang, Jing
- Subjects
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WIND speed measurement , *DYNAMIC pressure , *REYNOLDS number , *SPACE environment , *PRESSURE drop (Fluid dynamics) - Abstract
Accurate wind speed measurement in low-pressure conditions is crucial for the thermal performance validation and attitude control of stratospheric aircraft. As air density decreases, traditional wind speed measurement systems based on principles such as dynamic pressure, heat transfer, ultrasound, and particle velocimetry face significant challenges when applied in low-pressure environments, often failing to achieve the required measurement accuracy. This paper presents the development of a wind speed simulation system based on a rotation method designed to operate in low-pressure conditions, utilizing a space environment simulation chamber in conjunction with a high-precision turntable. The system was employed to conduct response tests on a constant heat flow thermal sphere anemometer within a stratospheric pressure range of 1 kPa to 30 kPa. The experimental results revealed that at extremely low Reynolds numbers, the probe signal exhibited increasing nonlinearity, significantly affecting the response curve at pressures below 15 kPa. While the sensitivity of the hot-sphere probe remained relatively stable at wind speeds above 5 m/s, it decreased nonlinearly as the pressure dropped when wind speeds fell below 5 m/s. Furthermore, this paper analyzes the impact of various interpolation methods on wind speed conversion errors, providing valuable data to support the future development and validation of stratospheric aircraft. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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8. Why do Experiments Fail? Six Practical Suggestions for Successful Online Experiments.
- Author
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Kim, Jungkeun
- Subjects
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TRAVEL literature , *PROBABILITY theory , *MOTIVATION (Psychology) - Abstract
Experiments are frequently used in the travel and hospitality literature to provide stronger evidence of causal relationships between various constructs. Recently, despite the use of online platforms for experimental studies, such studies have often failed to find significant results, as expected. To increase the probability of obtaining significant results for experiments using online panels, this paper suggests six practical recommendations across three categories: (i) handling less homogenous online participants; (ii) understanding and managing different motivations and abilities in online participants; and (iii) using effective and transparent experimental designs and procedures. This paper provides the results of three empirical investigations to support these recommendations. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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9. Experimental Testing of Elastic Properties of Paper and WoodEpox® in Honeycomb Panels.
- Author
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Peliński, Krzysztof and Smardzewski, Jerzy
- Subjects
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WOOD products , *HONEYCOMB structures , *ELASTICITY (Physiology) , *AUXETIC materials , *MATHEMATICAL models - Abstract
The literature lacks comparisons of analytical and numerical calculations that have been verified experimentally for elastic constants of auxetic cells in cores manufactured from wood materials. The aim of this study was to determine the effect of auxetic cell geometry and the type of material used in their manufacture on elastic properties of the honeycomb panel core. This paper describes properties of the materials, from which core cells were modeled and presents mathematical models of cell properties. The method of numerical optimization of cell shape was specified, and the numerical calculations concerning modeled cells are given along with the course and results of experimental tests. Additionally, the results of analytical, numerical, and experimental tests were compared. Cell geometry had a considerable effect on elastic properties of honeycomb panel cores, particularly the angle of the cell wall. Moreover, geometric imperfections had a significant effect on the results of analytical calculations. Based on numerical calculations, satisfactory consistency between these results and experimental tests was obtained. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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10. Multimodal constructions revisited. Testing the strength of association between spoken and non-spoken features of Tell me about it.
- Author
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Lehmann, Claudia
- Abstract
The present paper addresses the notion of multimodal constructions. It argues that Tell me about it is a multimodal construction that consists of a fixed spoken and a variable, but largely obligatory multimodality slot on the formal side of the construction. To substantiate this claim, the paper reports on an experiment that shows that, first, hearers experience difficulties in interpreting Tell me about it when it is neither sequentially nor multimodally marked as either requesting or stance-related and, second, hearers considerably rely on multimodal features when a sequential context is missing. In addition, the experiment also shows that the more features are used, the better hearers get at guessing the meaning of Tell me about it. These results suggest that, independent of the question of whether the multimodal features associated with requesting or stance-related Tell me about it are non-spoken, unimodal constructions themselves (like a raised eyebrows construction), a schematic multimodality slot might be part of the constructions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. Morphosyntactic stereotypes of speakers with different genders and sexual orientations: an experimental investigation.
- Author
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Posio, Pekka, Kachel, Sven, and Uclés-Ramada, Gloria
- Abstract
Previous research has identified differences in language use between speakers representing different genders and sexual orientations, as well as stereotypical beliefs about the existence of such differences. The present paper investigates such stereotypical beliefs among speakers of two varieties of Spanish and explores whether linguistic stereotypes of gender and sexual orientation are stronger in a society with more conservative gender roles. We conducted an experiment where 252 speakers of European and Mexican Spanish were shown pairs of texts and sentences depicting the same event but differing in the use of morphosyntactic resources, creating stereotypically "masculine" and "feminine" variants of the same text or sentence. The informants were asked which of the variants was more likely uttered by a woman (rather than a man), a lesbian woman (rather than a straight woman), or a gay man (rather than a straight man). Some of the morphosyntactic features were strongly associated with speaker gender (e.g., use of first- and second-person singular) and others with lesbian (e.g., use of impersonal structures) or gay speakers (e.g., direct reported speech). Contrary to expectations, the responses did not differ according to informants' age, gender, or nationality. While the present study did not reveal any differences between the two societies, more cross-linguistic and cultural research is needed to elucidate the effect of society on morphosyntactic variation and stereotypes thereof. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
12. Investigation of a Gas-Pump-Driven Loop Heat Pipe.
- Author
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Rong, Yangyiming, Su, Weitao, Wang, Shuai, Du, Bowen, Mao, Zujun, and Zhang, Shaozhi
- Abstract
A loop heat pipe (LHP) is an efficient method of conserving energy in data center cooling applications. In scenarios where the installation is constrained by height or distance limitations, pump driving is needed. This paper examines the performance changes induced by a gas pump both experimentally and theoretically. An adjustable, oil-free linear compressor is utilized as a gas pump. The evaporator is a finned-tube heat exchanger and the condenser is a water-cooled plate heat exchanger. When the filling ratio of the working fluid is insufficient, employing a gas pump can enhance the heat transfer performance. However, when the filling ratio of the working fluid is sufficient, while the gas pump can increase the flowrate of the working fluid, the heat transfer rate (HTR) does not change significantly. In fact, it may reduce the energy efficiency ratio of the heat pipe. Infrared thermography has proven to be an efficient tool for estimating the area ratio of different zones within the evaporator, which is crucial for the output regulation of the compressor. The area ratio of the two-phase zone is nearly linear to the HTR. Through the establishment of a physical model of a gas-pump-driven loop heat pipe (GPLHP), the impacts of the LHP size and gas pump operation on the heat transfer performance are analyzed. It is found that the gas pump can extend the application range of the LHP, although it has a minimal impact on the maximum HTR. How to select a gas pump for an LHP is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
13. 基于变环量方法的农用轴流风机设计及性能优化.
- Author
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吴乐天, 邱绵靖, 刘志伟, and 丁涛
- Subjects
- *
WIND tunnel testing , *AXIAL flow , *LIVESTOCK housing , *WIND tunnels , *STRUCTURAL optimization - Abstract
With the increased usage of air filtration and deodorization devices in livestock houses, the demand of agricultural axial flow fans with higher pressure has been raised. To improve the aerodynamic performance of an agricultural axial fan and expand its operating range, a new axial fan was developed using the theory of variable circulation method design via wind tunnel experiments and numerical simulations. The purpose is to change the structural form at the hub of the existing blade to improve the internal flow pattern of the agricultural axial fan, so as to achieve the purpose of improving the aerodynamic performance of the agricultural axial fan and expanding the range of stable operation. In this paper, a new agricultural axial flow fan is designed using the variable circulation method with 0.91m agricultural axial flow fan size and target airflow as design parameters. Secondly, the structural parameters at the hub of the axial fan are optimized by combining the simulation results of the flow field of the designed fan. Factors such as hub diameter d, the placement angle α and the number of moving blades n are analyzed individually, revealing the basic law of the influence of the changes of these factors on the performance of the fan, and the influence of the changes of each factor on the internal flow field of the fan is observed in combination with post-processing. using the better intervals for each factor derived from the one-factor optimisation results, the ventilation volume Q and the energy efficiency ratio N were selected as response values, and a response surface simulation study was carried out for the hub diameter d, the placement angle α, and the number of moving blades n. The response surface simulation study was carried out for the hub diameter d, the placement angle α, and the number of moving blades n. The response surface functional equations were obtained and the better parameter combinations were determined. The correctness of the functional model is further verified by observing the flow field characteristics and external characteristics through post-processing. Finally, the optimised impeller was fabricated by 3D printing technology and wind tunnel tests were conducted, and the results of the actual tests further confirmed the accuracy of the optimisation results. The numerical simulation results of the study show that the optimum combination of these parameters is d=260 mm, α=-0.369°, and n=4 pieces. Experimental test results show that the optimized axial fan performance is better than initial axial fans. On the high-pressure level (120 Pa), the ventilation volume Q of agricultural axial fan increased by 163%, and the energy efficiency ratio N increased by 18.9%. This study proves the feasibility of the variable circulation method in the design of high-pressure agricultural axial flow fan, and the optimization of structural parameters can further reduce the internal vorticity of the fan. The optimized axial fan reduced the secondary flow in the internal flow field, increased the work capacity of the blades, and improved the aerodynamic performance of the fan, ensuring that the axial fan can achieve air circulation and regulation more efficiently in agricultural applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
14. Positioning Strategies in B2B Marketing: The Regulatory Focus Orientation.
- Author
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Kalafatis, Stavros P., Blankson, Charles, Boatswain, Marvyn L., and Tsogas, Markos H.
- Subjects
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REGULATORY focus theory , *INDUSTRIAL marketing , *DELPHI method , *MARKETING executives , *DEPENDENT variables - Abstract
PurposeDesign/methodology/approachFindingsOriginality/valueRelying on regulatory focus theory (RFT), this study examines the mechanisms that guide managers’ positioning-related decisions in business-to-business contexts. Specifically, this research answers two main questions: what motivates managers to recommend specific positioning strategies and what motivates related decisions regarding contextual and market conditions?Two studies are undertaken in this research. Using the Delphi method, Study 1 adopted an online scenario-based experimental design related to the positioning decisions of three companies. A panel of expert informants assisted in the design process. Study 2 tested the stability of the results from Study 1 and then extended the analysis through the introduction of an additional dependent variable and market feedback. The results of the scenario-based online surveys are subjected to partial least squares structural equation analyses.The findings are in line with regulatory focus theory and show that RFT can provide motivationally derived answers to questions regarding inter-manager differences in positioning decision-making under similar market and company conditions. The results further show that decisions made by marketing managers in B2B contexts are guided by a desire to achieve congruity (fit) between their regulatory focus and their positioning strategy. Moreover, there is a differential impact of the regulatory foci on the likelihood of changing a recommended strategy.This paper investigates the moderating effects of involvement, valence framing, and market feedback. The study finds that the valence of the recommendation of a positioning strategy moderates the relationship between regulatory focus and the type of positioning strategy. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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15. EXPERIMENTAL ANALYSIS OF FRICTION AND SLIDING FORCES IN THE PURE WHEEL - COMPOSITE BAR SYSTEM.
- Author
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Ravai-Nagy, Sandor, Țîțu, Aurel Mihail, and Pop, Alina Bianca
- Subjects
- *
FRICTION , *POLYURETHANES , *DIGITAL technology , *ARTIFICIAL intelligence , *DEEP learning - Abstract
This paper presents an experimental analysis of the interaction between polyurethane (PUR) feed wheels and composite bars (resin + fiberglass) used in feed mechanisms. The main objective of the study is to determine the friction and sliding forces between these components, which are essential for the optimal design of feed equipment. The experiment was conducted using an adapted device where the PUR wheels are fixed, and the composite bar performs translational movement. Composite bars with diameters of 16 mm and 30 mm, representing the lower and upper limits of the diameter range proposed for the feed mechanism, were tested. The clamping force of the wheels was varied in the range of 1-8 kN, and the resulting pressing force was measured for each case. The experimental results demonstrated a directly proportional relationship between the clamping force and the friction force up to a critical sliding point. The sliding force increased proportionally with the clamping force up to a limit value, after which it remained relatively constant. The coefficient of friction was found to be variable, depending on the clamping force and the diameter of the bar. The study concludes that the maximum pressing force on the PUR wheels should not exceed 3 kN to avoid sliding and ensure efficient feed force. Additionally, it was found that the diameter of the composite bar significantly influences the friction and sliding forces. Based on these results, concrete recommendations can be formulated for the design and optimization of feed mechanisms, thus contributing to the improvement of their performance and efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2024
16. Interdisciplinary Analysis and the Role of Experiments in Raw Materials and Technology Identification for Prehistoric Pottery in the Bistrița River Basin (Romania).
- Author
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Drob, Ana, Bolohan, Neculai, Vasilache, Viorica, Rățoi, Bogdan-Gabriel, and Brebu, Mihai
- Subjects
- *
ENERGY dispersive X-ray spectroscopy , *CERAMIC materials , *MICROSCOPY , *BRONZE Age , *SCANNING electron microscopy - Abstract
The paper presents an interdisciplinary study based on an experimental model for investigating clay sources to identify prehistoric human behavior regarding resources. The study focuses on the Middle Bronze Age (1955/1773–1739/1614 cal. BC) settlement of Siliştea-Pe Cetățuie in eastern Romania, where archaeological materials from the Costișa and Monteoru cultures were discovered. Standard criteria for macroscopic analysis and analytical techniques, such as optical microscopy (OM), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), Micro-Fourier Transform Infrared Spectroscopy (µ-FTIR), and thermal analysis (DTA and TG), were used to investigate the ceramic material from multiple points of view. The results showed that there were no significant differences between the ceramics of the two communities. Putting together the data obtained from macroscopic and physico-chemical analyses helped in partially reconstructing ancient human behaviors related to the production and use of ceramic vessels. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
17. Measuring socially appropriate social preferences.
- Author
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Carpenter, Jeffrey and Robbett, Andrea
- Subjects
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SOCIAL stability , *SOCIAL norms , *SOCIAL accounting , *PHILANTHROPISTS , *ALTRUISM - Abstract
This paper extends the literature on structural estimation of social preferences to account for the desire to adhere to social norms and hide one's true intentions via moral wiggle room. We conduct an experiment to test whether accounting for normatively appropriate behavior allows us to distinguish between preference types who care about outcomes versus adhering to social norms and whether the introduction of moral wiggle room undermines the stability of social preference estimates. We find that social preference estimates are remarkably robust to the inclusion of moral wiggle room. However, the representative agent is strongly motivated by norms and failing to account for this motive in our model causes us to overestimate how much agents care about helping those who are worse off. Using finite mixture models to endogenously identify latent preference types, we replicate previous work finding that the majority of subjects can be classified as strong or moderate altruists when normative concerns are not considered. Accounting for the normative appropriateness of decisions when categorizing participants, however, reveals different motives across types: strong altruists are only marginally concerned with norms while the moderate altruists are highly sensitive to them and, once norms are taken into account, don't care at all about the outcomes of others. Our results thus recast the prior findings in a new light. Rather than the two most common types being strong altruists and moderate altruists, we find that they are better described as strong altruists and norm followers. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
18. Experimental study on replacing ceramsite with quartz sand in hydraulic fracturing.
- Author
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Che, Yang, Huang, Zhongwei, Yang, Ruiyue, Zhang, Zhao, and Hui, Chengyu
- Subjects
- *
FRAC sand , *HYDRAULIC fracturing , *SCANNING electron microscopes , *PARTICLE size distribution , *STONE , *SAND - Abstract
Hydraulic fracturing effectively enhances production in the unconventional oil and gas industry. As we all know, proppant plays a vital role in the hydraulic fracturing. In this paper, the effects of proppant type, particle size, concentration, closure pressure, and other factors are studied by laboratory experiments. Based on the actual triaxial simulation device (TSD), quartz sand, ceramic, and coated sand are used as proppant, while sandstone, coal rock, shale, and granite are selected as the stone slate to experiment. The surface of the proppant was imaged by a surface profiler (SP) and scanning electron microscope (SEM) to compare the microscopic surface characteristics before and after the experiment. The particle size macroscopic distribution was measured by Mastersizer 2000. The results and innovation are as follows: This paper investigates the proppant crushing for hydraulic fracturing and provides an alternative evaluation method for proppant selection. The crushing laws of proppant under different pressures and stone slate are compared by using the experimental device. It is reliable for quartz sand to replace ceramic in deep layer of the field application. It also overturns the previous thinking. We believe this found holds the key toward systematically optimizing the development of unconventional reservoirs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
19. Experimental study on replacing ceramsite with quartz sand in hydraulic fracturing.
- Author
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Che, Yang, Huang, Zhongwei, Yang, Ruiyue, Zhang, Zhao, and Hui, Chengyu
- Subjects
- *
FRAC sand , *HYDRAULIC fracturing , *SCANNING electron microscopes , *PARTICLE size distribution , *STONE , *SAND - Abstract
Hydraulic fracturing effectively enhances production in the unconventional oil and gas industry. As we all know, proppant plays a vital role in the hydraulic fracturing. In this paper, the effects of proppant type, particle size, concentration, closure pressure, and other factors are studied by laboratory experiments. Based on the actual triaxial simulation device (TSD), quartz sand, ceramic, and coated sand are used as proppant, while sandstone, coal rock, shale, and granite are selected as the stone slate to experiment. The surface of the proppant was imaged by a surface profiler (SP) and scanning electron microscope (SEM) to compare the microscopic surface characteristics before and after the experiment. The particle size macroscopic distribution was measured by Mastersizer 2000. The results and innovation are as follows: This paper investigates the proppant crushing for hydraulic fracturing and provides an alternative evaluation method for proppant selection. The crushing laws of proppant under different pressures and stone slate are compared by using the experimental device. It is reliable for quartz sand to replace ceramic in deep layer of the field application. It also overturns the previous thinking. We believe this found holds the key toward systematically optimizing the development of unconventional reservoirs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
20. Causal inference with misspecified exposure mappings: separating definitions and assumptions.
- Author
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Sävje, F
- Subjects
- *
CAUSAL inference , *DEFINITIONS - Abstract
Exposure mappings facilitate investigations of complex causal effects when units interact in experiments. Current methods require experimenters to use the same exposure mappings to define the effect of interest and to impose assumptions on the interference structure. However, the two roles rarely coincide in practice, and experimenters are forced to make the often questionable assumption that their exposures are correctly specified. This paper argues that the two roles exposure mappings currently serve can, and typically should, be separated, so that exposures are used to define effects without necessarily assuming that they are capturing the complete causal structure in the experiment. The paper shows that this approach is practically viable by providing conditions under which exposure effects can be precisely estimated when the exposures are misspecified. Some important questions remain open. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
21. Randomness and One-way Functions.
- Author
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AGÜERO TREJO, José Manuel and CALUDE, Cristian S.
- Subjects
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MATHEMATICAL functions , *POLYNOMIAL time algorithms , *COMPOSITE numbers , *RANDOM numbers , *STRING theory - Abstract
This paper proposes a method using high-quality randomness for inverting a class of one-way functions in a pre-given time. Experimental results suggest that the method is better than the lexicographic search. [ABSTRACT FROM AUTHOR]
- Published
- 2024
22. Experimental, theoretical and numerical study on flexural behavior of hybrid steel‐GFRP reinforced concrete slabs.
- Author
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Meghdadi, Zeinab and Khaloo, Alireza
- Subjects
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REINFORCED concrete , *REINFORCING bars , *FINITE element method , *STEEL bars , *GLASS fibers , *CONCRETE slabs - Abstract
This paper presents the experimental results of six full‐scale one‐way reinforced concrete slabs with variations in reinforcement detailing. Test specimens consisted of two reference concrete slabs reinforced fully with glass fiber reinforced polymer (GFRP) rebars or with steel rebars and four hybrid‐reinforced slabs. The variables included the arrangement of rebars, mechanical reinforcing ratio, and the ratio of steel rebar area to GFRP rebar area. The fabricated specimens were subjected to four‐point loading until failure in the strong floor laboratory. Experimental results indicated that hybrid reinforcement enhances stiffness compared to FRP reinforcement and provides a higher load‐bearing capacity than steel reinforcement. Also, it was observed that FRP bars placed as tensile reinforcement, similar in number and diameter size to steel bars placed as compressive reinforcement in a slab result in the highest ultimate capacity. Moreover, it was observed that while the mechanical reinforcing ratio contributes to the overall behavior of hybrid‐reinforced concrete slabs, the ratio of steel rebar area to GFRP rebar area is not considerably effective. Furthermore, image processing was employed to determine the exact crack widths of specimens after failure. Finally, finite element modeling results showed good agreement with the experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
23. Experimental Investigations on the Vectoring Characteristics of the Axisymmetric Divergent Bypass Dual Throat Nozzle.
- Author
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Wang, Y. S., Xu, J. L., and Huang, S.
- Abstract
The greater thrust-vector angles can be obtained in the axisymmetric divergent bypass dual throat nozzle (ADBDTN). Meanwhile, the axisymmetric divergent bypass dual throat nozzle also has a certain flow adaptive capability and can solve the starting problems existing in the non-vectored state. In the present paper, the results of experimental investigations on the vectoring characteristics of the axisymmetric divergent bypass dual throat nozzle are given. By comparing the structures of the flow field obtained from experiments and numerical simulations as well as the wall static pressure distributions along the flow direction and circumferential direction, it can be seen that, as the nozzle pressure ratio (NPR) increases, flow reaches a critical state near the nozzle exit, and incompletely expanded flow in the cavity continues to accelerate after flowing out of the nozzle, a diamond-shaped structure with alternating shock and expansion wave systems appears downstream of the nozzle exit, and the flow field structures in the cavity are no longer changed when NPR ≥ 6. In addition, the static pressure distributions on the upper and lower wall surfaces of the cavity of the nozzle obtained from the experiments are in good agreement with the results of the numerical simulations, and the wall static pressures in the cavity are basically symmetrically distributed at various circumferential angles. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
24. Theory vs. experiment: The rise of the dynamic view of proteins.
- Author
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Neal, Jacob P.
- Subjects
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X-ray crystallography , *MOLECULAR biology , *HISTORICAL analysis , *BIOLOGISTS , *PHILOSOPHERS - Abstract
Over the past century, the scientific conception of the protein has evolved significantly. This paper focuses on the most recent stage of this evolution, namely, the origin of the dynamic view of proteins and the challenge it posed to the static view of classical molecular biology. Philosophers and scientists have offered two hypotheses to explain the origin of the dynamic view and its slow reception by structural biologists. Some have argued that the shift from the static to the dynamic view was a Kuhnian revolution, driven by the accumulation of dynamic anomalies, while others have argued that the shift was caused by new empirical findings made possible by technological advances. I analyze this scientific episode and ultimately reject both of these empiricist accounts. I argue that focusing primarily on technological advances and empirical discoveries overlooks the important role of theory in driving this scientific change. I show how the application of general thermodynamic principles to proteins gave rise to the dynamic view, and a commitment to these principles then led early adopters to seek out the empirical examples of protein dynamics, which would eventually convince their peers. My analysis of this historical case shows that empiricist accounts of modern scientific progress—at least those that aim to explain developments in the molecular life sciences—need to be tempered in order to capture the interplay between theory and experiment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. The Additional Effects of Adaptive Survey Design Beyond Post-Survey Adjustment: An Experimental Evaluation.
- Author
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Zhang, Shiyu and Wagner, James
- Subjects
- *
REGRESSION analysis , *RESPONDENTS , *COST - Abstract
Adaptive survey design refers to using targeted procedures to recruit different sampled cases. This technique strives to reduce bias and variance of survey estimates by trying to recruit a larger and more balanced set of respondents. However, it is not well understood how adaptive design can improve data and survey estimates beyond the well-established post-survey adjustment. This paper reports the results of an experiment that evaluated the additional effect of adaptive design to post-survey adjustments. The experiment was conducted in the Detroit Metro Area Communities Study in 2021. We evaluated the adaptive design in five outcomes: 1) response rates, 2) demographic composition of respondents, 3) bias and variance of key survey estimates, 4) changes in significant results of regression models, and 5) costs. The most significant benefit of the adaptive design was its ability to generate more efficient survey estimates with smaller variances and smaller design effects. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. Using injected additive materials to improve pipeline transportation in real-world experiments and computational fluid dynamics.
- Author
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Shaker AL-SAYYAB, Ali Khalid and ABDULWAHID, Mohammed A.
- Subjects
- *
HEAVY oil , *PETROLEUM , *COMPUTATIONAL fluid dynamics , *PIPELINE transportation , *PRESSURE drop (Fluid dynamics) - Abstract
In this paper, an experiment has been conducted where additive materials have been added to heavy crude oil to improve transportation. This is done on a pipeline length of 186 km. During the experiment, materials will be added to the inner pipeline to lubricate the heavy crude oil fiber and reduce the pressure drop. The additive materials, which are Drag-Reducing Agents (DRAs) (These are polymers that reduce the friction between the crude oil and the pipeline walls) are injected into heavy crude oil at different doses (two materials); the doses are 4, 6, 8, 10, and 12. A comparison between the cases before and after this additive has been obtained in the pipeline for velocity magnitude, vorticity magnitude, pressure drop, and wall shear stress. It can be observed that doses (8, 10, and 12) obtained a wide range of flow rates with fewer pressure drops than other dose points. The pressure at the city of Al-Faw has been found, and the maximum values are 1.482, 1.413, and 1.399 MPa for doses 12, 8, and 6, respectively. The simulation was done with COMSOL 5.4 Multiphasic software. Flow ranges increase as the dose increases. Shear stress increases with mass injection rate. Transporting heavy crude oil long distances is easier with additive materials. After the additive materials are added, crude oil will be transported for a long time without pressure drops, increasing the flow rate. The two turbines pump heavy crude oil through a 48 inches wide and 186 km long pipeline. These pipelines transfer heavy crude oil from the refinery to Al-Faw City. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. Investigation on the creep models of the NEPE solid propellant.
- Author
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Wang, Jingxin, Fang, Qinzhi, and Sha, Baolin
- Subjects
- *
SOLID propellants , *PROPELLANTS - Abstract
In this paper, the creep experiments of Nitrate Ester Plasticized Polyether (NEPE) propellant under eight different stress levels are carried out. The creep experimental data is discussed with different constitutive models, and it is found that the four parameters fluid constitutive model and the composite time-hardening constitutive model can be used to fit the experiment data better. The composite time-hardening constitutive model is more suitable to predict the long-term creep behavior based on the short-term creep behavior. The accuracy of the constitutive model is proved by comparing the predicted results with the experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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28. Preparation and performance study of SiO2 aerogel thermal insulation coating with nanoporous structure for wind turbine blade surface.
- Author
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He, Jianjun, Huang, Caiyuan, Pu, Min, Shu, Zhonghu, Duan, Zihao, Zeng, Zijing, and Li, Jianwei
- Subjects
- *
THERMAL insulation , *WIND turbine blades , *SURFACE coatings , *AEROGELS , *MANUFACTURING processes , *PERFORMANCE theory , *RAW materials - Abstract
To prepare a base layer of thermal insulation for the surface of wind turbine blades, we utilized SiO2 aerogel material with a nanoporous structure as the thermal insulation layer of an inorganic composite photothermal de-icing coating. We further investigated the influence of raw material ratio and process on the thermal insulation layer's performance. By adjusting the process parameters, the microstructure and characteristics of the SiO2 aerogel thermal insulation coating were controlled. Microstructure scanning and EDS analysis were employed to assess the results. The results of the experiment suggest that, as opposed to brush coating, atomized spraying is a better technique for creating SiO2 aerogel thermal insulation coating. The coating possesses excellent mechanical stability and applicability, maintaining a coating wear rate within 5% after 20 wear cycles under a load of 1734 N/m2, and the coating achieves the highest class 0 surface adhesion to the substrate surface. The coating exhibits exceptional heat insulation performance, reaching a temperature of 32.7 °C after five spraying cycles, which is 20.0 ∼ 29.4 °C higher than the surface without producing a complete heat insulation layer. The SiO2 aerogel aqueous slurry has a viscosity of 31.3 ∼ 36.9 mPa∙s, which is capable of forming a uniform membrane surface when sprayed at a 60° angle at 0.95 MPa pressure. Consequently, this paper's design of photothermal thermal insulation offers strong anti-abrasion and excellent thermal insulation, presenting a new avenue for scientific investigation into coating photothermal de-icing. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
29. Numerical and Experimental Analysis of Buckling and Post-Buckling Behaviour of TWCFS Lipped Channel Section Members Subjected to Eccentric Compression.
- Author
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Jankowski, Jacek, Kotełko, Maria, and Ungureanu, Viorel
- Subjects
- *
NUMERICAL analysis , *ECCENTRICS (Machinery) , *NEWTON-Raphson method , *COLD-formed steel , *FINITE differences - Abstract
The paper presents a static analysis of the buckling and post-buckling state of thin-walled cold-formed steel (TWCFS) lipped channel section beam-columns subjected to eccentric compression. Eccentricity is taken into consideration relative to both major and minor principal axes. An analytical–numerical solution to the buckling and post-buckling problems is described. The solution is based on the theory of thin plates. Equations of equilibrium of section walls are derived from the principle of stationary energy. Then, to solve the problem, the finite difference (FDM) and Newton–Raphson methods are applied. Linear (buckling) and nonlinear (post-buckling) analyses are performed. As a result, pre- and post-buckling equilibrium paths are determined. Comparisons of the obtained numerical results, FE simulation results, and experimental test results are carried out and presented in comparative load-shortening diagrams. Additionally, a comparison of the buckling forces and buckling modes obtained from theoretical analysis and experiments is presented. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. The use of Virtual Reality (VR) to assess the impact of geographical environments on walking and cycling: a systematic literature review.
- Author
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Ghanbari, Marzieh, Dijst, Martin, McCall, Roderick, and Perchoux, Camille
- Subjects
- *
CYCLING , *CONVENIENCE sampling (Statistics) , *HEAD-mounted displays , *EVIDENCE gaps , *CIVILIAN evacuation , *VIRTUAL reality - Abstract
Background: Geographical environments influence people's active mobility behaviors, contributing to their physical and mental health. The use of Virtual Reality (VR) in experimental research can unveil new insights into the relationship between exposure to geographic environments and active mobility behaviors. This systematic review aims to (1) identify environmental attributes investigated in relation with walking and cycling, using VR, (2) assess their impacts on active mobility behaviors and attitudes, and (3) identify research gaps, strengths and limitations in VR-based experimental research. Methods: Articles published between January 2010 and February 2022 within five databases (PubMed, Scopus, EBSCO, IEEE Xplore, and Cochrane Library) were explored using three keywords and their synonyms: Virtual Reality, Active mobility behavior, and Geographical environments. Studies focusing on indoor environments, driving simulation, disease-specific groups, non-relevant disciplines (e.g. military, emergency evacuation), VR methodology/software optimization, and those with static participants' involvement were excluded. The full protocol is available from PROSPERO (ID = CRD42022308366). Results: Out of 3255 articles, 18 peer-reviewed papers met the selection criteria, mostly focusing on walking (83%). Most studies used head-mounted displays (94%) and relied on convenience sampling (72% below 100 participants). Both static (33%) and dynamic (45%) environmental attributes have been investigated, with only 22% of them simultaneously in the same virtual environment. Greenness and crowd density were the most frequent attributes, rather consistently associated with emotional states and movement behaviors. Few studies have taken into account participant's previous VR experience (33%) and cybersickness (39%) while both are likely to affect an individual's perception and behavior. Conclusions: Future research should explore a broader range of environmental attributes, including static and dynamic ones, as well as a more complex integration of these attributes within a single experiment to mimic the effect of realistic environments on people's active mobility behaviors and attitudes. Larger and more diverse population samples are deemed required to improve result generalizability. Despite methodological challenges, VR emerges as a promising tool to disentangle the effect of complex environments on active mobility behaviors. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Incorporating Adaptive Survey Design in a Two-Stage National Web or Mail Mixed-Mode Survey: An Experiment in the American Family Health Study.
- Author
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Zhang, Shiyu, West, Brady T, Wagner, James, and Gatward, Rebecca
- Subjects
- *
FAMILY health , *RESEARCH questions , *RURAL families , *RURAL population , *POSTAL service , *INTERNET surveys - Abstract
This article presents the results of an adaptive design experiment in the recruitment of households and individuals for a two-stage national probability web or mail mixed-mode survey, the American Family Health Study (AFHS). In the screening stage, we based the adaptive design's subgroup differentiation on Esri Tapestry segmentation. We used tailored invitation materials for a subsample where a high proportion of the population was Hispanic and added a paper questionnaire to the initial mailing for a subsample with rural and older families. In the main-survey stage, the adaptive design targeted the households where a member other than the screening respondent was selected for the survey. The adaptations included emailing and/or texting, an additional prepaid incentive, and seeking screening respondents' help to remind the selected individuals. The main research questions are (i) whether the adaptive design improved survey production outcomes and (ii) whether combining adaptive design and postsurvey weighting adjustments improved survey estimates compared to performing postsurvey adjustments alone. Unfortunately, the adaptive designs did not improve the survey production outcomes. We found that the weighted AFHS estimates closely resemble those of a benchmark national face-to-face survey, the National Survey of Family Growth, although the adaptive design did not additionally change survey estimates beyond the weighting adjustments. Nonetheless, our experiment yields useful insights about the implementation of adaptive design in a self-administered mail-recruit web or mail survey. We were able to identify subgroups with potentially lower response rates and distinctive characteristics, but it was challenging to develop effective protocol adaptations for these subgroups under the constraints of the two primary survey modes and the operational budget of the AFHS. In addition, for self-administered within-household selection, it was difficult to obtain contact information from, reach, and recruit selected household members that did not respond to the screening interview. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Experimental and Theoretical Studies on the Shear Performance of Concrete Beams Reinforced with Fiber-Reinforced Polymer Stirrups.
- Author
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Zhao, Jun, Bao, Xiaohu, Yang, Shoudi, Wang, Zike, He, Hongwei, and Xu, Xiazheng
- Subjects
- *
FIBER-reinforced plastics , *CONCRETE beams , *REINFORCED concrete , *STIRRUPS , *STRUT & tie models , *PERFORMANCE theory - Abstract
In this paper, the shear behavior of concrete beams reinforced with FRP stirrups is studied. The shear performances of six concrete beams with a size of 150 mm × 300 mm × 3000 mm under four-point loading up to failure were experimentally analyzed. The critical parameters included the shear span to depth ratio (λ) and stirrup spacing (S). The test results revealed that as λ increased from 1 to 2, 3, and 4, the ultimate shear capacity of the beam decreases by 50.5%, 67.7%, and 69.2%, respectively. Meanwhile, as S increased from 100 mm to 150 mm and 200 mm, the ultimate shear capacity decreased by 16.1% and 44.6%, respectively. A new shear capacity calculation model of concrete beam reinforced with FRP stirrups was also proposed, which further considered the shear capacity of the FRP stirrups on the basis of the shear capacity of an RC beam without stirrups using the strut-and-tie model. Finally, the experiment and calculation results of 56 beam specimens reinforced with FRP stirrups extracted from this paper and previous studies were compared using the calculation models proposed in this paper, in order to evaluate the accuracy of these calculation models. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Mathematical modeling and experimental research on grounding current calculation of converter transformer core.
- Author
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Zhou, Xiu, Tian, Tian, Wu, Peng, Luo, Yan, Bai, Jin, He, Ninghui, and Li, Xiuguang
- Subjects
- *
MATHEMATICAL models , *FINITE element method , *INSULATING oils , *MAGNETIC cores , *CURRENT transformers (Instrument transformer) - Abstract
When the converter transformer core is grounded at multi-points, a fault loop will be formed and a circulation will be generated, leading to local overheating of the magnetic core and decomposition of insulating oil. Therefore, the converter transformer core will be single point grounded. As a rare internal lead of converter transformer, the ground current on the core ground lead can often reflect the running state of converter transformer. In this paper, theoretical analysis, modeling simulation and experimental research are carried out on the ground current of converter transformer at one point. Firstly, according to the structure characteristics of converter transformer, the analytical modeling of ground current is carried out. Secondly, based on the structure characteristics of oil paper insulation, the equivalent capacitance of converter transformer is calculated. Then, the analytical and finite element simulation model of converter transformer is established, and the ground current of converter transformer is calculated. Finally, the correctness of the proposed scheme is verified by measuring the grounding current of converter transformer core. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Accountability and taxation: Experimental evidence.
- Author
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Sjursen, Ingrid Hoem
- Subjects
- *
TAXATION , *GOVERNMENT revenue , *INTERNAL revenue , *CONSUMPTION tax , *NATURAL resources - Abstract
The Rentier State Hypothesis states that taxation promotes government accountability. The argument is that citizens demand more accountability for spending of tax revenue than for spending of windfall revenue (e.g., natural resource revenue and aid). This paper presents causal evidence from a between-subject experiment that tests the effect of taxation on demand for accountability. To investigate the underlying mechanisms of the effect, the design focuses on two main features that distinguish tax from windfall revenue: Tax revenue is produced by citizens' work and has been in their possession before it is collected as tax. The main finding is that taxation causes a higher demand for accountability when both features of taxation are present, consistent with the Rentier State Hypothesis. The paper sheds light on the political economy of government revenues, and contributes to our understanding of how features of the tax system shape behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
35. Current and transconductance mode full/half‐wave rectifiers realized with only one active block.
- Author
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Petrović, Predrag B.
- Subjects
- *
MONTE Carlo method , *ELECTRONIC control , *ELECTRIC current rectifiers - Abstract
Summary: This research paper introduces a novel active building block for full/half‐wave (inverse) rectifier circuits, eliminating the need for passive elements. The paper presents two alternative implementations: a current mode approach utilizing MO‐CFTA (multiple output current follower transconductance amplifier) and a transconductance mode approach utilizing MO‐VDTA (multiple output voltage differencing transconductance amplifier). Both circuit configurations exhibit favorable zero‐crossing characteristics and exceptional linearity. The transconductance mode rectifier enables electronic control of the output current signal by adjusting the applied bias currents. The circuits are designed with simplicity and compactness in mind, making them highly suitable for integration into IC circuits. The analysis investigates the impact of non‐idealities and parasitic effects, although the absence of passive elements results in minimal parasitic effects. Simulation results conducted using 0.18‐μm CMOS technology and a ±0.9‐V supply voltage align closely with the theoretical predictions. Furthermore, Monte Carlo simulations and corner analysis are employed to evaluate the circuit's robustness. To validate the feasibility of the proposed solution, experimental tests are performed using commercially available components. The designs are implemented on Cadence Virtuoso, and post‐layout measurements are conducted to further verify the proposed solutions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
36. A review of simulation and experiment research on cutting mechanism and cutting force in nanocutting process.
- Author
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Chen, Dongju, Wu, Shuiyuan, He, Yazhong, Luo, Yuchi, and Wang, Xiang
- Subjects
- *
CUTTING force , *CONDENSED matter physics , *DIAMOND cutting , *PAPER arts , *MACHINE parts - Abstract
Nanocutting is a method of direct machining in nanomanufacturing field, and it is an important ultraprecision machining method. Nanocutting technology adopts single-point diamond cutting and nanoprobe scratching methods to make the machining accuracy of parts reach the nanometric scale. It is the method with the highest machining accuracy at present, so it is widely used in the processing of precision components. At the same time, nanocutting technology can be used to process nanostructures and provide processing methods for basic research in condensed matter physics. This paper summarized the cutting mechanism and cutting force in the nanocutting process, including the mechanism of nanocutting and brittle–ductile transition. The influence of RTS, temperature, wear and subsurface phase transformation on cutting performance is also discussed. At the same time, the characteristics of cutting force and friction coefficient during the cutting process are reviewed. After that, the simulation and experiment research of the nanocutting process are analyzed. At the end of the paper, the challenges and prospects of nanocutting technology are proposed and summarized. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
37. Experimental and Numerical Investigation on Pile Foundation Underpinning Structure System in Urban Overpass.
- Author
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Yan, Lei, Gou, Xiaoying, Guo, Zhengchao, Zhang, Xin, Jiang, Yu, Ran, Xingwen, Chen, Guanwen, and Yue, Kefeng
- Subjects
- *
BUILDING foundations , *ADHESIVE joints , *BORED piles , *PROGRESSIVE collapse , *CONCRETE joints , *URBANIZATION , *FINITE element method , *RESIN adhesives - Abstract
In view of the complexity of the pile foundation underpinning structure system and the stringent requirements of the construction process, this paper briefly describes the necessity of introducing epoxy resin reinforcing adhesive of planting rebar in the design of pile foundation underpinning beam structure to improve the mechanical properties of the reinforced beam new and old concrete joint surfaces and proposes a new type of pile foundation replacement beam system construction method by "chiseling + prestressed reinforcement + epoxy resin reinforcing adhesive". This paper uses an actual pile foundation underpinning project of an urban overpass as a prototype, designs and creates a model structure with a similarity ratio of 1/6, and performs repeated progressive static loading tests to study the load carrying capacity, displacement change, and other properties of the strengthened replacement structure, as well as analyses and distorts the overall working performance and failure mode of them. On this basis, the prototype structure's finite element analysis model was built, and the finite element analysis results were compared with the test results to obtain the mechanical properties and deformation characters of the actual pile foundation underpinning structure system corresponding to the actual underpinning beam load. This paper's study can lay the theoretical and experimental foundation for the smooth development of similar projects. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
38. Experimental and thermal‐structure coupling analysis for oil and water‐swellable packer.
- Author
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Huang, Xin, Xu, Tao, and Liu, Yang
- Subjects
- *
MATERIAL plasticity , *PETROLEUM , *HIGH temperatures , *RUBBER - Abstract
It has been widely acknowledged that traditional packers will lose their elastic performance in the context of long periods of operation due to plastic deformation. This paper will introduce a swellable packer that can reduce the failure cases of production effectively. The deformation of the packer rubber in different media and temperatures has been analyzed. The pressure test of several packer rubber under different media is carried out in this paper. The reasonable expansion clearance between the rubber tube and the well wall is obtained by strength calculation to ensure the sealing reliability of the packer. Finally, the thermomechanical coupling calculation of the packer with different structural sizes is carried out. Experiments at different temperatures show that the higher saline concentration is associated with a lower expansion rate and a larger expansion rate in clear water. At the same time, the expansion of volume in clear water increases. In addition, the higher the external temperature is, the larger the temperature gradient is. When the temperature of the outer ring is between 100°C and 140°C, the internal temperature rises to 37°C under the thermomechanical coupling effect. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
39. Experimental and numerical investigations on stress concentration factors of concrete filled steel tube X-joints.
- Author
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Diao, Yan, He, Shiyi, Wang, Yukai, and Tu, Liu
- Subjects
- *
CONCRETE-filled tubes , *STRESS concentration , *FINITE element method , *MULTIPLE regression analysis , *TENSION loads , *AXIAL loads - Abstract
An SHS-CFSHS X-joint is fabricated by welding two square hollow section (SHS) braces to a concrete-filled square hollow section (CFSHS) chord. In this paper, the stress concentration factors (SCFs) of SHS-CFSHS X-joints are investigated through experimental tests and finite element analysis (FEA), with the hot spot stress method serving as the analytical approach. Eight specimens are designed and manufactured, with FE models built in software ANSYS. These FE models are validated against the test results. The specimens are tested under brace axial tension to determine the SCFs of the X-joints. It shows that the concrete filled in the chord effectively reduces the SCFs of the X-joints. To further explore various load conditions and the influence of the parameters, FEA is carried out and a total of 64 FE models are built. Based on the FEA results, multiple regression analysis is used to obtain the SCF formulae of SHS-CFSHS X-joints under axial tension load and in-plane bending load in the brace, respectively. Comparison and analysis of the SCF results obtained from experimental tests, the proposed formulae, and FE simulations reveal that the formulae presented in this study are both conservative and suitable for predicting SCFs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Experimental Study on a Photovoltaic Direct-Drive and Municipal Electricity-Coupled Electric Heating System for a Low-Energy Building in Changchun, China.
- Author
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Zhao, Qi, Liu, Xiaoyue, Gu, Shijie, Tao, Jin, Wu, Wende, Ma, Shuang, and Jin, Hongwen
- Subjects
- *
ELECTRIC heating , *BUILDING-integrated photovoltaic systems , *INDUSTRIALIZED building , *AC DC transformers , *ELECTRIC power consumption , *GREENHOUSE gas mitigation - Abstract
This paper takes a low-energy building in Changchun, China, as an object to test and study the characteristics of two heating modes, AC/DC (Alternative current/Direct current) switching and AC/DC synthesis, from the perspectives of temperature change, irradiation intensity, power generation, electricity consumption, etc. Firstly, the experimental research was conducted under two heating cable modes by establishing mathematical models and a test rig, and it was found that the photoelectric conversion efficiency on sunny, cloudy, and overcast days was 18%, 14.5%, and 12%, respectively. A simulation model was established by TRNSYS to run an ultra-low-energy building throughout the year. It was found that the highest and lowest monthly power generation occurred in February and July, respectively. The annual power generation of the system was 6614 kWh, and the heating season power generation was 3293.42 kWh. In the current research, the DC electricity consumption was slightly higher than the AC electricity consumption. Under conditions of similar radiation intensity and power generation, the indoor temperature of the AC/DC synthesis cable heating mode were 1.38% higher than the AC/DC switching heating able mode, and the electricity consumption were 10.9% and 4.76% higher, respectively, than those of the AC switching heating cable mode. This is of great significance for clean-energy heating, energy savings, and emissions reduction in northern China. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. SEED DISCHARGE PERFORMANCE TEST OF AIR SUCTION SEED DISCHARGER FOR SMALL VEGETABLE SEEDS.
- Author
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Yanjun LI, Yichao NING, Fuxiang XIE, and Yang Bai
- Subjects
- *
AIR flow , *GAS flow , *ORTHOGONALIZATION , *GAS chambers , *FLUID pressure - Abstract
Vegetable precision planting agronomy is suitable for my country's current vegetable planting system, and the air-suction vegetable precision planter is currently the most important work tool in my country. This paper designs a kind of air-absorbing vegetable precision sower for the problems of small vegetable seeds with small grains, poor mobility and high difficulty in achieving uniform sowing of small seeds. First, Fluent software is used to simulate and analyze the flow field of the air chamber in the seed metering device, and the pressure and velocity of the fluid in the air chamber are analyzed. Through the comparison of the pressure distribution cloud chart and the velocity distribution cloud chart, the influence of different apertures, holes, vacuum degree, and gas chamber depth on the flow field of the gas chamber is analyzed. The air suction seed discharger test bench was set up and orthogonal test was carried out, and the test results showed that the optimal parameter combination was 3.5 kPa vacuum degree of the air chamber, 2.4 mm diameter of the type hole, and 18 r/min rotational speed of the seed discharging disk. The high-speed photographic test was carried out under the optimal parameter combination, and the results showed that leakage of suction, adsorption of 1 seed, and adsorption of multiple seeds appeared in the process of suction, and it is important for the development of the air suction precision machine for small seeded vegetables with better performance. The results showed that the phenomenon of leakage, adsorption of 1 seed and adsorption of multiple seeds occurred in the process of seed suction, which provided a reference basis for the development of a better performance of the air-absorption precision planter for small seeds. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. DESIGN AND EXPERIMENT OF ANNULAR AIR-BLOWING ASSISTED SEED GUIDING DEVICE FOR CORN NO-TILL SEEDER.
- Author
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Haojie ZHOU, Chunling ZHANG, Tao LIU, Yazi WANG, Jun FANG, and Antai HU
- Subjects
- *
AIR pressure , *PROBLEM solving , *NO-tillage , *SOWING , *SEEDS - Abstract
In the process of seed introduction, there is a problem of seed falling disorderly due to the collision between the seed and tube wall, which seriously affects the uniformity of seed spacing in the field. To solve this problem, this paper designed a kind of annular air-blowing auxiliary seed guide device. After a series of simulation experiments, theoretical research, and high-speed camera bench experiments, the optimal parameter selected combination of the critical structure of the seed guide device. The experimental results showed that when the annular air-blowing assisted seed guide tube was used, the positive air pressure was 2 KPa, the airway angle was 150°, the airway outlet width was 12 mm, and the distribution pore diameter was 4 mm. When the forward speed was 6 km/h (the rotation speed of the seed metering disc was 25.30 rpm), the seed sowing effect was the best in the seed guide device; the qualified rate was 88.36%, and the coefficient of variation was 12%. This study provides a reference for improving seed spacing uniformity and can be used to optimize seed guide tubes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. The causal effect of cultural identity on cooperation.
- Author
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Butler, Jeffrey V. and Fehr, Dietmar
- Subjects
- *
CULTURAL identity , *CHINESE people , *TORTURE , *COOPERATION , *ECONOMIC activity , *PUBLIC universities & colleges - Abstract
The impact of culture on non-kin cooperation has been singled out as critical for economic activity. However, causal evidence of culture's influence on cooperation remains scant. In this paper we provide such evidence, focusing on two key components of culture: preferences and beliefs. Adopting the view that culture is one aspect of an individual's multi-faceted self-concept (identity) we conduct a Prisoner's Dilemma experiment with first- and second-generation Chinese immigrants at a large US public university. In a two-by-two design, we exogenously vary: i) the salience of participants' American or Chinese cultural identities; and ii) the capacity for culture to affect beliefs by randomly providing previous-session cooperation-rate information. Comparing behavior across cultures and information conditions, our results suggest a prominent role for both preferences and beliefs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
44. First impressions matter: evaluating the importance of online reputation in social networking sites for initial trust in virtual work partners.
- Author
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Martinelli Watanuki, Hugo and de Oliveira Moraes, Renato
- Subjects
- *
ONLINE social networks , *VIRTUAL work , *TRUST , *VIRTUAL communities , *STRUCTURAL equation modeling , *PUBLIC spaces , *REPUTATION - Abstract
Purpose: The purpose of this paper is to identify the practices that owners of public profiles in social networking sites can leverage to actively build online reputation and to evaluate the impact of the adoption of such practices on the initial formation of trust toward these individuals when they are presented as new virtual work partners. Design/methodology/approach: A theoretical model was developed and an experiment with 233 participants was utilized to assess the model using partial least squares structural equation modeling. Findings: The results suggest that individuals can build their online reputations in public profiles of social networking sites via a series of practices of self-disclosure of information and that the adoption of these practices has significant effects on the initial formation of trust toward the profile owner in virtual work contexts. Categorization mechanisms such as stereotyping, unit grouping and reputation categorization have been found to contribute to the initial formation of trust, both from an affect and cognition-based perspectives. Originality/value: Little is known about the information disclosure practices in public profiles of social networking sites that new work partners can adopt to facilitate the formation of trust between them before they start working together. This study has contributed to the existing body of literature by clarifying these practices and the relative importance of online reputation to the initial formation of trust during the outset of a new virtual work relationship. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
45. Electrodynamic Forces in Main Three-Phase Busbar System of Low-Voltage Switchgear—FEA Simulation.
- Author
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Łapczyński, Sebastian, Szulborski, Michał, Kolimas, Łukasz, Sul, Przemysław, Owsiński, Maciej, Berowski, Przemysław, Żelaziński, Tomasz, and Lange, Andrzej
- Subjects
- *
SHORT-circuit currents , *FINITE element method , *ELECTRICAL energy , *PHENOMENOLOGICAL theory (Physics) , *ELECTRIC circuits - Abstract
This paper concerns the effects of electrodynamic forces that act on current paths that are part of high-grade industrial distribution switchgear. This work is composed of experimental and simulation sections. In the experimental section, the short-circuit tests are presented and the occurrence of electrodynamic forces are shown in a visible way. The formation of electrodynamic forces in the current circuits of electrical energy distribution systems is related to the flow of high currents, but mostly it is related to short-circuit currents. In order to highlight these phenomena, the detailed specification of the parameters during tests is displayed. In the simulation section, the physical phenomenon of electrodynamic forces is being captured by employing a detailed real-scale model of switchgear and current paths. Therefore, the authors proposed employment of the FEM (finite element method) in order to obtain values of electrodynamic forces acting on the current paths by executing the detailed 3D coupled simulation. The analysis of the results and aftermath effects of their interactions provided interesting conclusions that concerned the operation of such power distribution layouts in critical short-circuit conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
46. Formation of Richterite in the Enstatite–Diopside System in the Presence of K2CO3–Na2CO3–CO2–H2O Fluid: Implications for the Processes of Mantle Metasomatism.
- Author
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Limanov, E. V., Butvina, V. G., Safonov, O. G., Spivak, A. V., Van, K. V., and Vorobey, S. S.
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- *
METASOMATISM , *BANKING industry , *RAMAN spectroscopy , *FLUIDS , *AMPHIBOLES , *PERIDOTITE - Abstract
The paper presents data on the formation of K–Na richterite in the enstatite + diopside association with K2CO3–Na2CO3–CO2–H2O fluid at 3 GPa and 1000°C as a model for the formation of this mineral in peridotites of the upper mantle. Richterite formation depends on the (H2O + CO2)/(K2CO3 + Na2CO3) and K2CO3/Na2CO3 ratios in the starting material. A high concentration of alkaline components in the fluid leads to the decomposition of clinopyroxene, the formation of olivine, and a change in the component composition of the pyroxene and amphibole. Fluids with a high potassium concentration are favorable for the formation of K-richterite similar in composition to that formed in metasomatized peridotites of the upper mantle. In some cases, such a fluid leads to the decomposition of amphibole and stabilization of alkaline melt. An increase in the activity of the sodium component results in richterite similar in composition to richterite from lamproites. The clarified relations can be used to assess the activities of fluid components and conditions for the formation of K-richterite. To update the data bank of the Raman spectra of minerals, the largest and most homogeneous amphibole crystals of different compositions were studied. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
47. The democracy effect: A weights-based estimation strategy.
- Author
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Dal Bó, Pedro, Foster, Andrew, and Kamei, Kenju
- Subjects
- *
DEMOCRACY , *NEW democracies - Abstract
• We propose a new estimator of the Democracy Effect that overcomes selection effects. • It weighs the behavior of each type of voter by its prevalence in the whole population. • We derive the distribution of this new weights-based estimator of the democracy effect. • Applications to two experiments find a significant effect in one but not the other. Dal Bó et al. (2010) show experimentally that the effect of a policy may be greater when it is democratically selected than when it is exogenously imposed. In this paper we propose a new and simpler estimation strategy that does not require information on the vote of subjects in the exogenous treatment. The new estimation strategy is based on calculating the average behavior under democracy by weighting the behavior of each type of voter by its prevalence in the whole population (and not conditional on the vote outcome). We derive the distribution of this new weights-based estimator of the democracy effect and show it eliminates selection effects under certain conditions. We apply the new estimation strategy to the data in Dal Bó et al. (2010) and to the data from a new experiment for which we cannot use the previous estimation strategy as we do not have information on how subjects would have voted in the exogenous treatment. We find a significant democracy effect in the former but not on the latter application. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. Flow-Induced Vibration Experiment in Fuel Pin Bundle with Heavy Liquid Metal Flow: Test Section Design and Measurement Methods.
- Author
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Di Piazza, I., Martelli, D., Carrelli, C., Rovai, T., Raschioni, V., Ramacciotti, M., Spezzaneve, A., Ferretti, D., and Mongiardini, G.
- Abstract
The present paper describes the experimental setup for flow-induced vibration in a fuel pin bundle test section with flowing lead. The test section is a 37-pin mock-up representative of the GEN-IV ALFRED fuel assembly and is manufactured to investigate the turbulence-induced vibrations in the pins. The pins are instrumented with longitudinal strain gauges (SGs), and with three SGs per monitoring point, the displacement signal can be recovered in terms of amplitude and frequencies. To achieve this goal, a complex algorithm is implemented in the data acquisition control system of the test section. The test section will be installed in the Heavy Liquid metal Experimental loop for Nuclear Applications (HELENA) facility at the ENEA Brasimone R.C., in which a mechanical pump for lead circulation is present. The test matrix is proposed with the mass flow rate varying from 10 to 50 kg/s and a constant temperature of 450°C for all the tests. Briefly, the experimental procedure is presented to carry out the experimental campaign. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. Is Chatgpt a menace for creative writing ability? An experiment.
- Author
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Niloy, Ahnaf Chowdhury, Akter, Salma, Sultana, Nayeema, Sultana, Jakia, and Rahman, Sayed Imran Ur
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DATA analysis , *ARTIFICIAL intelligence , *CONTENT analysis , *UNIVERSITIES & colleges , *DESCRIPTIVE statistics , *QUANTITATIVE research , *CREATIVE ability , *EXPERIMENTAL design , *PRE-tests & post-tests , *STATISTICS , *CONTENT mining , *COLLEGE students , *STUDENT attitudes , *WRITTEN communication ,RESEARCH evaluation - Abstract
Background: The increasing prevalence of Artificial Intelligence (AI) language models, exemplified by ChatGPT, has sparked inquiries into their influence on creative writing skills in educational contexts. This study aims to quantitatively investigate whether ChatGPT's use negatively affects university students' creative writing abilities, focusing on originality, content presentation, accuracy, and elaboration in essays. The research adopts an experimental approach to shed light on this concern. Objective: This study aims to quantitatively investigate whether the utilization of ChatGPT, an AI chatbot, adversely affects specific dimensions of creative writing skills among university students, with an emphasis on originality, content presentation, accuracy, and elaboration. Method: The experimental study involves 600 students from 10 universities, divided into a control and an experimental group (EGp). The EGp incorporates ChatGPT in their creative writing process as an intervention. The study evaluates originality, content presentation, accuracy, and elaboration, utilizing the Wilcoxon Signed‐Rank Test for analysis. Results and Conclusion: The findings reveal a detrimental association between ChatGPT use and university students' creative writing abilities. Analysing both machine‐based and human‐based assessments substantiates earlier qualitative observations regarding ChatGPT's adverse impact on creative writing. This study highlights the necessity of approaching AI integration, particularly in creative writing disciplines, with caution. While AI tools have merits, their integration should be thoughtful, considering the potential drawbacks. These insights inform future research and educational practices, guiding the effective incorporation of AI while nurturing students' writing skills. Lay Description: What is already known about this topic: ChatGPT poses an ethical dilemma regarding its use in the field of academiaQualitative claims and opinions have been raised in prior studies regarding its use in the creative writing processPrior studies have both supported and opposed its use but with very limited quantitative approaches while most of the opinions remain qualitativeSome prior studies opine in support of ChatGPT's ability as an authorSeveral factors measuring creativity has been identified by previous studies but a constructive approach in the light of advanced Artificial Intelligence (AI) based chatbots like ChatGPT is missing in such literature What this paper adds: An experimental approach to provide a valid quantitative proof of the qualitative claims over ChatGPT's detrimental effect towards creativity in writing, which was absent in prior studiesA multifactor‐based formula to measure creativity in a quantitative formA quantitative view of the factors that are affected in either a positive way or a negative way in a user by ChatGPT, providing a holistic picture to determine its extent of useA statistical and theoretical understanding over an unexplored topic like creative writing in the light of ChatGPTA quantitative proof why ChatGPT should not be considered as an author Implications for practice and/or policy: Educators may implement changes in assigning tasks to students compared to their earlier practices, based on the identified factors that are being affected negatively, to ensure ChatGPT does not hinder a student's creativity at a greater extentThe extent of using ChatGPT should be limited to self‐learning as positive effect was experienced through the experimentPolicymakers may use the findings of the study to impose strict policies in academia for ensuring academic integrity (Example: must use of plagiarism detecting software for checking scripts, assigning tasks to students which require more analytical abilities, providing tasks which are not properly readable by LLM's like ChatGPT such as image‐based questions, case studies etc.) [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Relationship between the College Student and the Campus Club: An Evolutionary Game Theory Analysis.
- Author
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Duan, Lei, Wang, Zhong, Zhu, Guanyu, and Zhang, Yahui
- Subjects
- *
GAME theory , *COLLEGE students , *STUDENT adjustment , *ACADEMIC motivation , *CLUBS - Abstract
In this paper, we use an evolutionary game theory approach to build a relationship model of students and clubs for the purpose of improving student enthusiasm for participating in club activities. First, the process of the model building is introduced, which mainly includes the basic assumptions and the equilibrium point stability analysis. Based on this analysis, we find that the motivation adjustment of students and clubs is a dynamic process and that unilateral efforts alone cannot achieve an ideal result. Then, we use real data from Yanshan University to evaluate the model, the results of which indicate that the model can analyze the relationship between students and clubs effectively. Finally, we provide relevant suggestions based on the model established in this study, whereby we contribute a theoretical basis and practical guidance for how students can actively participate in clubs, as well as how clubs can better develop themselves. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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