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In this study, the failure mode and mechanism of single-box two-compartment segmental box girders under flexural shear coupling were experimentally studied. Loading tests were conducted on five scaled girders, and the effects of the design parameters on the shear performance were analyzed. The test variables included the loading methods, ratio of internal to external prestressing tendons, and key joint types (vertical and horizontal keys). The test results indicated that different loading methods produce different stress characteristics and damage modes; however, the difference in the ultimate load capacity was negligible. The greater the number of internal prestressing tendons, the greater the bearing capacity. The stress increment of the internal bottom prestress reinforcement was great than the external prestressing tendons. Monolithic box girders could maintain approximately 1.8 times as much pressure as segmental box girders. With the increase of shear span ratio, the load carrying capacity of the segmental beam decreases. Vertical key teeth had a slightly higher bearing capacity than horizontal key teeth. Vertical keys are recommended for segmental box girders owing to their excellent structural properties and ease of construction. and the structure. AASHTO can better predict the shear capacity of segmental beams, while the Chinese code is applicable to segmental beams with appropriate hoop ratio. [ABSTRACT FROM AUTHOR]

The wooden arch corridor bridge is a typical representative of Chinese wooden bridges, holding significant historical research value. Currently, these bridges face issues of severe component deformation and insufficient load-bearing capacity. To address these problems, this study employs CFRP reinforcement on the components of wooden arch corridor bridges to reduce deformation and enhance load-bearing capacity. Experimental research on CFRP reinforcement has yielded the elastic modulus of the bonding interface. Given the lack of an accurate numerical model for wooden arch corridor bridges, this study establishes a precise numerical model by setting parameters based on load test data from wooden arch corridor bridges. The elastic modulus obtained from the experiments is input into the numerical model for analysis. The results indicate that CFRP exhibits excellent reinforcement performance, with the load-bearing capacity of the reinforced damaged components still reaching 75%–85% of their original capacity, while the load-bearing capacity of the reinforced undamaged components increases to 130%–140% of their original capacity. The failure modes of the CFRP-reinforced wooden components suggest that allowing for some gaps in the bonding of CFRP can enhance overall ductility. The application of CFRP to wooden arch corridor bridges also demonstrates favorable reinforcement effects, increasing the load-bearing capacity of the arch surface by approximately 20%, thereby providing a theoretical basis for the reinforcement of wooden arch bridge frameworks. [ABSTRACT FROM AUTHOR]

This research presents an experimental, analytical, and numerical study to predict the flexural behavior of reinforced concrete hidden and wide beams embedded in slabs. The experimentally studied parameters of testing eight specimens include beam depth, beam width, and beam eccentricity from the column. The obtained test results were compared to the predictions of finite element analysis using the ANSYS program. A numerical parametric study was conducted by the ANSYS program to explore other parameters affecting the ultimate flexural strength of beams. The studied parameters encompass concrete compressive strength, steel reinforcement strength, bottom reinforcement ratio, top-to-bottom reinforcement ratio, and web reinforcement ratio. The results revealed that an increase in beam depth led to higher ultimate load and secant stiffness, along with a decrease in deflection. The increase in beam width significantly affected beam depth, resulting in increased ultimate load and secant stiffness and a slight decrease in deflection. The increase in beam eccentricity from the column resulted in a decrease in ultimate load and secant stiffness while increasing the deflection. Comparisons between experimental and numerical results were made against calculations based on the ECP 203-2017 and ACI 318-19 codes, and the comparison yielded satisfactory results. [ABSTRACT FROM AUTHOR]

High-performance steels are ideal for highway bridge due to their strength, corrosion resistance, toughness, and weld-ability. Innovative designs have been used, such as using corrugated webs to provide improved shear stability without needing transverse stiffeners. Experimental work identified triangle corrugated plates with three samples and compared with two corrugation shapes from previous studies. The study conducted FEA to analyze the effect of corrugation type and depth on sandwich corrugated beam behavior using four types (trapezoidal, rectangular, triangle, and octagonal) and three depths (20-30-40 mm). The tested beams showed optimal results when the plate's penal length equaled its height. The corrugation shape affects the beam shear strength, and the best type was the rectangular corrugation. A good agreement is found when comparing the FE results to the experimental findings. The best type, according to the FE results, was rectangular with a 20 mm depth. This study shows that corrugated beams can withstand higher ultimate loads than traditional steel girders due to improved web stability, demonstrating their superior strength against applied loads. [ABSTRACT FROM AUTHOR]

A study is conducted, it researches the design, making and bypass of the drone propeller. Discovering the streamlined qualities of the different propeller designs using the computational apparatus, the software is utilized. A mini-summarized propeller having such mechanisms was fabricated and the trials done confirmed their success. Whilst the multi material approach mitigates against lightness with strength, durability will be the weakest link in that process. With weight and streamlined failures, fragility is always a factor. This assessment should aid in overhauling current drone propulsion systems, such as durability and efficiency, to enhance performance and increase persistence. The FSI system was employed to study airflow patterns using fans and stress factors by printing parts with PLA, ABS and PGA printing materials. The air was channeled over the materials, simulating actual flight, to evaluate the materials' strength. The drone model DJI MINI 3 PRO was subjected to the experimental tests of the speed and the maximum height. The height of the fan in MINI 3 PRO could be higher with the maximum speed of 37.3 km/h and it would be 187 meters in MINI 2 PRO concerning this aspect. ABS material speeds and jumps higher than the PGA material. It turns out that the 3 PRO propeller fans have the highest thrust force of 5.1 m/s at the highest speed, which is different from the 2 PRO propeller fan that measures only 3.2 m/s. The 3 experiences 0.155 mm distortion, whereas the 2 produced 0.103 mm. PLA material has the least value of influence among all. [ABSTRACT FROM AUTHOR]

Copyright of Turkish Journal of Trauma & Emergency Surgery / Ulusal Travma ve Acil Cerrahi Dergisi is the property of KARE Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Possible deterioration of a rock's structure and mechanical properties due to chemical reactions between the host rock, formation water, and CO2 requires due attention. In this study, cylindrical sandstone specimens obtained from the Hanna Formation, Wyoming, were prepared under three treatment conditions: dry, submerged in water, and treated with water + CO2 for one week at a pressure of 5 MPa and room temperature. Specimens were subjected to three effective confining pressures of 5, 15, and 25 MPa. The mechanical test results show that water + CO2 treatment, on average, decreases the peak strength and elastic modulus of the specimens by 36% and 20%, respectively, compared to dry specimens. For all three effective confining pressures, the dry specimens exhibited higher compressive strengths, larger Young's moduli, and more brittle behavior. CO2-treated specimens showed significantly lower calcite contents. [ABSTRACT FROM AUTHOR]

Squeezing-induced buckling or flexural deformation of rock layers always occurs on consequent rock slopes and laminated roof of tunnels or underground openings. To reveal the mechanical mechanism and inducing factors of this instability, tests on cuboid rock samples comprised of bedding sandstone under horizontal squeezing stress were conducted. In addition, numerical modeling based on cohesive-element-model was conducted to further reveal the influence of inter-layer bonding strength on the mechanical behavior of laminated rock. According to the results, remarkable size effects exist on the buckling-fracture characteristics of tested samples. Subjected to the same horizontal stress, tested samples with different dimensions have quite different failure patterns, including upper buckling-lower shearing, integral buckling and end squashing. It is recommended that the length-thickness ratio of tested samples for buckling failure research should be less than 150/8. Moreover, numerical simulations indicate that failure characteristics of the samples are greatly influenced by the bedding structure such as bedding thickness and inter-bedded bonding strength. Buckling deformation at one end becomes quite obvious when inter-bedded bonding strength decreases to a smaller value. The research results will not only contribute to understanding the buckling mechanism of stratified rock mass subjected to horizontal stress, but also provide a guidance for similar experimental design in terms of sample preparation, loading and monitoring. [ABSTRACT FROM AUTHOR]

Critical structures such as hospitals, high-precision manufacturing facilities, telecommunications centers, and fire stations, especially, need to maintain their functionality even during severe earthquakes. In this sense, seismic isolation technology serves as a vital design method for preserving their functionality. Seismic isolators, also known as earthquake isolation systems, are used to reduce the effects of earthquakes on buildings by isolating them from the ground they are located on. By ensuring that less acceleration and force demand is transmitted to the superstructure, both the building and the equipment and the devices in the building are prevented from being damaged by earthquakes. This experimental study aims to conduct vibration tests on a small-scale multi-story steel-building model equipped with a specially designed rolling-type seismic base isolation system. The relationship between the test model and the prototype was achieved by frequency simulation. The tests will be performed on a shake table under six different earthquake accelerations to examine the model's dynamic behavior. The primary goal is to evaluate the isolation performance of the rolling-type seismic base isolator under seismic loads, with a focus on recording the vibrations at the top of the test building. It has been observed that the isolator placed at the base of the building significantly reduced the peak acceleration and displacement values of the floor motion. Under the most severe earthquake record applied to the shake table, the acceleration at the top of the building with the isolator was found to be reduced by approximately 50%, compared to the non-isolated case. [ABSTRACT FROM AUTHOR]

During an explosion, a building's stability is directly impacted by reinforced concrete (RC) columns. However, there is currently no theoretical analysis model that can precisely predict damage to RC columns after close-in/contact explosions. In the present study, the local damage response of RC columns under a rectangular charge was experimentally and numerically investigated, and a theoretical analysis model for predicting local damage after a contact explosion was developed. The experimental results verify the effects of concrete strength, standoff distance, transverse reinforcement spacing, and axial load on damage to RC columns. When the standoff is 100 mm, increasing the axial load can effectively reduce the damage to the center of the column surface. Numerical simulations were carried out to study the effect of different parameters on concrete damage, showing that the damage span of reinforced concrete increases with increased stirrup distance; however, when the stirrup distance decreases to 70 mm, the distance between the stirrups and the explosives is too close to limit the damage. The prediction model innovatively considers the attenuation of steel cross-section transmission and the characteristics of rectangular charges. Compared with traditional semi-empirical calculation models, it can accurately calculate local damage caused by contact explosions on reinforced concrete columns. [ABSTRACT FROM AUTHOR]

This study aims to examine the effectiveness of Conceptual Problem Solving-based learning in improving student conceptual understanding of Newtonian mechanics. The quasi-experimental method with a nonrandomized control group pretest-posttest design was used to compare students conceptual in the experimental and control class. The subjects in this study were 69 first-year students of the Physics Education study program at one of the state universities in Yogyakarta. Force Concept inventories are used to assess students conceptual understanding of Newtonian mechanics. The findings revealed that there was significant difference in the increase in students conceptual understanding between the experimental and control groups. The increase in conceptual mismatch in experimental class students using CPS learning was higher (N-gain = 0.33) compared to control class students using direct instruction learning (N-gain = 0.11), although both groups experienced an increase. This study provides a real picture that the CPS technique can be used as a more successful strategy to improve the quality of physics learning, especially in improving knowledge of basic topics that are often difficult for students to understand, one of which is Newton's Law. [ABSTRACT FROM AUTHOR]

Stresses caused by ionizing radiation can also damage tissues and organs through the circulatory system. In this study, we aimed to determine the radioprotective effect of propolis, a natural and powerful antioxidant product, against oxidative liver damage caused by cranial irradiation. Thirty-two male albino Sprague–Dawley rats, divided into four groups, were designed as sham group, irradiation (IR) group, propolis plus IR, control group of propolis. Biochemical parameters were measured in liver tissue of rats. While Total enzymatic superoxide scavenging activity (TSSA) and non-enzymatic superoxide scavenging activity (NSSA), glutathione peroxidase (GSH-Px) activities of all groups were statistically significantly higher than rats receiving only-irradiation, Glutathione-S-transferase (GST) activity in the IR group was significantly lower than in the sham control group and IR + propolis group. Superoxide dismutase (SOD) activity in the IR group was found to be significantly higher than both the sham control group and the propolis control group, but lower than the IR + propolis group. Malondialdehyde level and xanthine oxidase activity were higher in the IR group than in the other groups. Compared to the sham control group, in the group treated with propolis, a significant elevation in antioxidant parameters, specifically TSSA, NSSA, SOD, and GST activities, was noted, with corresponding increases of 32.3%, 23.2%, 47.6%, and 22.6%, respectively. Our findings show that propolis can be a radioprotective agent against ionized radiation damage by increasing antioxidant activity and reducing oxidant stress in liver tissue. [ABSTRACT FROM AUTHOR]

Objectives: To assess the impact of topical papaverine administration in complete and incomplete colonic anastomosis, by examining bursting pressure, hydroxyproline concentration, collagen content, inflammation levels, inflammatory cell infiltration, neoangiogenesis, and necrosis grades. Methods: We performed an experimental study on rats, in which they were divided into the following 4 groups of 16 subjects each. Group 1 [complete anastomosis (CA) without papaverine (CA -P) group], Group 2 [CA with papaverine (CA +P) group], Group 3 [incomplete anastomosis (ICA) without papaverine (ICA -P) group], and Group 4 [ICA with papaverine (ICA +P) group]. Results: The lymphocyte infiltration score of the ICA +P3 (day 3) group was significantly higher compared to the ICA -P3 group (p = 0.018). The median Ehrlich–Hunt score (p = 0.012), inflammation score (p = 0.026), and neutrophil infiltration score (p = 0.041) of the CA +P7 (day 7) group were significantly lower than the corresponding data of the CA -P7 group. Additionally, the necrosis score of the ICA +P7 group was significantly lower than that of the ICA -P7 group (p = 0.014). Conclusions: Data from the current study reveal that, although topical papaverine seems to suppress inflammation in anastomosis tissue and reduce necrosis at 7 days, definite conclusions regarding its impact on anastomotic leak cannot be drawn without further studies investigating anastomotic wound healing and anastomotic leak, preferably with both shorter- and longer-term evaluations. [ABSTRACT FROM AUTHOR]

Tunnel stability is influenced by the rheological properties of the surrounding rock. This study, based on the Ganshen high-speed railway tunnel project, examines the rheological characteristics of siltstone and sandstone through laboratory tests and theoretical analysis. Rheological curves and parameters are derived, revealing the time-dependent deformation mechanisms of the surrounding rocks. A numerical simulation model is created using these parameters to analyze deformation and stress characteristics based on different rock levels and inverted arch closure distances. Results indicate that sandstone follows the Cvisc model, with the Maxwell elastic modulus increasing under higher loads while the viscous coefficient decreases. The vault displacement is mainly affected by the surrounding rock strength; lower strength leads to greater displacement, which also increases with the closure distance of the inverted arch. These findings are crucial for determining the optimal closure distance of inverted arches in sandstone conditions. [ABSTRACT FROM AUTHOR]

Featured Application: This paper proposes a protocol for researchers, ergonomists, and industrial practitioners to design and carry out well-structured experiments that allow for reliable and valid comparisons between different exoskeleton designs or configurations, considering factors such as user characteristics, task demands, environmental conditions, and subjective user perceptions. This paper proposes a modular protocol for the designing of experimental studies to analyze exoskeletons used in industrial settings to support manual material handling (MMH). Despite exoskeleton technologies starting to be highly commercialized and present in workplaces, research still lacks a standardized procedure for analyzing the impact of these devices on workers. The protocol presented in this paper outlines a step-by-step procedure, including the parameters to be collected and analyzed in a research study. Moreover, the approach could be easily adapted to meet the specificity of a wide range of exoskeletons. The main novelty of the protocol is thus to support the experimental design and analysis of studies assessing the overall impact of exoskeletons on workers. To implement the protocol, the selected case study concerned a palletizing task involving the MMH of 12 cardboard boxes, weighing 10 kg. The results from physiological signals and pressure insoles show that the protocol is comprehensive and can be utilized by researchers evaluating different occupational exoskeletons for assistance during MMH (both active and passive), with modifications to specific parts based on the type of exoskeleton being assessed or the variables of interest. [ABSTRACT FROM AUTHOR]

Novel experimental data have been presented on the influence of the surface tension of a liquid on the dispersity of droplets in the spray cone of an ejection atomizer with forward and swirling gas feeds. The droplet-size distributions were measured with the optical method of small angles of the indicatrix of scattering. A decrease of nearly 10–17% in the median diameter of droplets of distilled water in the spray cone has been demonstrated with reduction in the coefficient of surface tension of water as a result of adding surfactants to it. [ABSTRACT FROM AUTHOR]

High-volume space structures are characterized by high combustible loads, rapid fire development, difficulty in firefighting, and potential building collapse risks, making early fire detection particularly crucial. The effectiveness of early fire detection technologies relies on their ability to adapt to the characteristics of smoke-dominant combustion products in the protected space. However, there is a lack of targeted research on the characteristics of the smoke generated during the early low-power stages of fires in high-volume spaces, which has not supported the development of early fire detection technologies for such environments. To address this, this paper presents an experimental study that, for the first time, collects data on fire smoke parameters such as temperature, velocity, concentration, and particle size at heights ranging from 6.5 m to 18.5 m using lightweight sensors. The study analyzes the characteristic and correlations of these parameters and their impact on early fire detection in high-volume spaces for the first time, presenting variation patterns in the plume velocity and particle size distribution of early fire smoke with height. It identifies three patterns of particle size distribution, contrasting with previous studies, and offers a qualitative explanation for these findings. This research enhances the understanding of early fire smoke signals in large spaces and offers valuable insights for developing more accurate and efficient fire detection strategies and technologies. [ABSTRACT FROM AUTHOR]

This study focuses on the evaluation of the Notch Stress Intensity Factor (NSIF) as a key parameter for estimating the material's master failure curve in API 5L pipe steel. The research encompasses both experimental investigations and numerical validations to comprehensively assess the applicability of NSIF in predicting failure behavior. Through a series of controlled experiments, various notched specimens were subjected to different loading conditions, allowing the determination of NSIF values. Concurrently, a numerical framework was developed using finite element analysis to simulate the stress distribution near the notches. The experimental results were compared with the numerical simulations to validate the accuracy of the proposed approach. This research contributes to enhancing the understanding of how NSIF can serve as a reliable indicator of failure potential in industrial applications, particularly in the context of pipeline structures. The findings highlight the significance of NSIF-based predictions in ensuring the integrity and safety of materials under varying loading conditions.

The damage effect of the explosion shock wave generated by the explosion of the air to air missile warhead on the aircraft skin structure is influenced by various factors，and the function mechanism is relatively com plex，so that a large number of experimental and computational samples are required to evaluate the damage of shock waves to aircraft skin structures accurately. The static explosion experiments of aluminum alloy reinforced plates with fixed supports are performed，and their dynamic response and deformation patterns under shock wave loading are analyzed. The finite element analysis software LS-DYNA is used to simulate the structural response under explosive impact，and the simulation model is validated by comparing with the experimental results. The results show that the target plate is prone to tensile failure with tearing at the fixed boundary when the hole area ratio of the reinforced plate exceeds 1‰，and increasing the hole diameter or the number of holes enhances the risk of perforation damage between holes. The target deformation increases with the incident angle of explosion，and the target deflection can increase by more than 30% when the angle increases from 30° to 60° at a constant explosion distance.

Abstract This research presents an experimental, analytical, and numerical study to predict the flexural behavior of reinforced concrete hidden and wide beams embedded in slabs. The experimentally studied parameters of testing eight specimens include beam depth, beam width, and beam eccentricity from the column. The obtained test results were compared to the predictions of finite element analysis using the ANSYS program. A numerical parametric study was conducted by the ANSYS program to explore other parameters affecting the ultimate flexural strength of beams. The studied parameters encompass concrete compressive strength, steel reinforcement strength, bottom reinforcement ratio, top-to-bottom reinforcement ratio, and web reinforcement ratio. The results revealed that an increase in beam depth led to higher ultimate load and secant stiffness, along with a decrease in deflection. The increase in beam width significantly affected beam depth, resulting in increased ultimate load and secant stiffness and a slight decrease in deflection. The increase in beam eccentricity from the column resulted in a decrease in ultimate load and secant stiffness while increasing the deflection. Comparisons between experimental and numerical results were made against calculations based on the ECP 203-2017 and ACI 318-19 codes, and the comparison yielded satisfactory results.

Due to its advantages of higher heat flux and wider operating temperature range, sodium heat pipes have shown promising application prospects in related miniaturized and unmanned nuclear reactor platforms. The accuracy of the working fluid’s evaporation accommodation coefficient (acc) in sodium heat pipes holds significant importance for their thermal transport analysis. According to existing research, it has been found that the evaporation characteristics of the working fluid are related to the contact surface condition, and the value of acc is significantly influenced by temperature. Therefore, the impact of different internal parameters and operating temperatures on acc of sodium within the sodium heat pipe was studied by using experimental methods. By varying parameters such as heating power, inclination angle, filling ratio, and capillary wick, the axial outer wall temperature and internal vapor-phase temperature under steady-state conditions were measured using the thermocouple placed on the outer wall and the radially movable thermocouple inside the heat pipe. The experimental results reveal that the vapor-phase temperature distribution is non-uniform in the radial direction on steady-state condition, exhibiting a certain thermal gradient. Different methods for selecting vapor temperatures, in combination with measured outer wall temperature, were employed to derive the experimental values of acc under different work conditions and operating temperatures based on the Hertz-Knudsen-Schrage equation. Analysis demonstrates a good linear relationship between the logarithmic value of acc and the logarithmic saturation pressure within the sodium heat pipe, which remains consistent for different sodium contents and inclination angles. However, when using the wall temperature of the adiabatic section or the vapor-phase temperature of the adiabatic section as the vapor temperature, acc tends to be relatively small due to the influence of radial thermal resistance and the wetting properties of liquid sodium, particularly below the wetting transition temperature (550 ℃), but it still satisfied a logarithmic linear relationship. Nevertheless, as the contact angle between the liquid sodium and the capillary wick approached 0°, the effect of the capillary wick became more pronounced, leading to a significant increase in acc due to the axial spreading facilitated by the excellent wetting properties of liquid sodium, therefore, the value of acc after the wetting contact angle transition temperature is also relatively larger. Overall, there is still a good linear relationship between the logarithmic value of acc and the logarithmic saturated vapor pressure. Finally, through fitting analysis, an empirical relationship for acc of sodium within the heat pipe at different temperatures was established, which can be used to predict acc under various operating conditions.

This study aims to examine the effectiveness of Conceptual Problem Solving-based learning in improving student conceptual understanding of Newtonian mechanics. The quasi-experimental method with a nonrandomized control group pretest-posttest design was used to compare students conceptual in the experimental and control class. The subjects in this study were 69 first-year students of the Physics Education study program at one of the state universities in Yogyakarta. Force Concept inventories are used to assess students conceptual understanding of Newtonian mechanics. The findings revealed that there was significant difference in the increase in students conceptual understanding between the experimental and control groups. The increase in conceptual mismatch in experimental class students using CPS learning was higher (N-gain = 0.33) compared to control class students using direct instruction learning (N-gain = 0.11), although both groups experienced an increase. This study provides a real picture that the CPS technique can be used as a more successful strategy to improve the quality of physics learning, especially in improving knowledge of basic topics that are often difficult for students to understand, one of which is Newton's Law.

Abstract Stresses caused by ionizing radiation can also damage tissues and organs through the circulatory system. In this study, we aimed to determine the radioprotective effect of propolis, a natural and powerful antioxidant product, against oxidative liver damage caused by cranial irradiation. Thirty-two male albino Sprague–Dawley rats, divided into four groups, were designed as sham group, irradiation (IR) group, propolis plus IR, control group of propolis. Biochemical parameters were measured in liver tissue of rats. While Total enzymatic superoxide scavenging activity (TSSA) and non-enzymatic superoxide scavenging activity (NSSA), glutathione peroxidase (GSH-Px) activities of all groups were statistically significantly higher than rats receiving only-irradiation, Glutathione-S-transferase (GST) activity in the IR group was significantly lower than in the sham control group and IR + propolis group. Superoxide dismutase (SOD) activity in the IR group was found to be significantly higher than both the sham control group and the propolis control group, but lower than the IR + propolis group. Malondialdehyde level and xanthine oxidase activity were higher in the IR group than in the other groups. Compared to the sham control group, in the group treated with propolis, a significant elevation in antioxidant parameters, specifically TSSA, NSSA, SOD, and GST activities, was noted, with corresponding increases of 32.3%, 23.2%, 47.6%, and 22.6%, respectively. Our findings show that propolis can be a radioprotective agent against ionized radiation damage by increasing antioxidant activity and reducing oxidant stress in liver tissue.

The paper is devoted to the study of the dependences of the characteristics of partial discharges on magnetic induction. The design of the experimental setup has been developed. It allows applying both high voltage and current comparable to the operating one. The setup includes a high voltage source (dielectric tester), a current flow circuit, a high voltage current transformer and a sample of XLPE insulated cable. The operation of the electrical circuit of the experimental setup is simulated using software. The modeling has shown that if the operational electrical strength of the current transformer insulation is present, the high-voltage potential cannot contact the current flow circuit. After this, modeling of the magnetic field inside the insulating layer is carried out. Based on the developed design, an experimental setup is created. To record partial discharges, an artificial defect is created in a cable sample. The results of magnetic field modeling made it possible to estimate the magnetic induction in the field of an artificial cable defect. Next, experimental studies are carried out to assess the influence of the magnetic field of the cable core current on the characteristics of partial discharges. The measurement results have showed a decrease in the average apparent charge of partial discharges and partial discharge power with increasing current. In addition, waveforms are compared, but no significant differences are found. The magnetic field of the current may influence the PD performance in the long term due to its possible influence on the direction of growth of the electrical tree structure.

ABSTRACT This research aims to test students' understanding of fraud cases using the persuasion elaboration model, namely the influence of argument framing, source credibility, and emotional condition on the decision to reveal fraud. This research method uses a 2x2x2 online laboratory experiment between subjects with 127 accounting students from Universitas Hayam Wuruk Perbanas. The results showed that the argument framing (positive vs. negative) did not make a significant difference. In contrast, source credibility (high vs. low) and emotional condition (good vs. bad) made a significant difference in accounting students' decisions to reveal fraud. This research contributes to behavioral accounting theory developed with communication science in predicting the behavior of prospective accountants. ABSTRAK Penelitian ini bertujuan untuk menguji pemahaman mahasiswa atas kasus kecurangan menggunakan model elaborasi persuasi, yaitu pengaruh pembingkaian argumen, kredibilitas sumber, dan kondisi emosi terhadap keputusan mengungkapkan kecurangan. Metode penelitian ini menggunakan eksperimen laboratorium online antar subjek 2x2x2 dengan partisipan sebanyak 127 mahasiswa akuntansi Universitas Hayam Wuruk Perbanas. Hasil penelitian menunjukkan bahwa pembingkaian argumen (positif vs negatif) tidak memberikan perbedaan yang signifikan, sedangkan kredibilitas sumber (tinggi vs. rendah), dan kondisi emosi (baik vs. buruk) memberikan perbedaan yang signifikan dalam keputusan mahasiswa akuntansi mengungkapkan kecurangan. Penelitian ini berkontribusi pada teori akuntansi keperilakuan yang dikembangkan dengan ilmu komunikasi dalam memprediksi perilaku calon akuntan.

Calculating the parameters of the ground shock induced by an underground explosion is a complex energy coupling problem. It is difficult to establish a unified ground shock coupling law from limited test data. This paper summarizes the research results obtained at home and abroad and systematically analyzes the coupling mechanism of craters formed by an underground explosion and the ground shock. The differences between the concepts of “closed-explosion critical depth” and “equivalent closed-explosion critical depth” are clearly explained. The spreading of the ground shock energy is attributed to the explosive expansion of the air cavity, revealing a linear relationship between the volume of the cavity region (or the volume of the crack region) and the ground shock energy associated with the underground explosion. The proportionality factor is related to the mechanical properties of the medium and is independent of the magnitude of the explosion equivalent. Based on this, a theoretical calculation formula and conversion method for the ground shock coupling coefficient were established. Explosion tests were conducted in clay and Plexiglass under varying burial depths. The test results were consistent with the theoretically calculated results. Our study provides a theoretical basis for the design of explosion-resistant structures in underground engineering.

Abstract The effects of the novel synthetic peptide, A7-1, on wound healing and skin grafts were evaluated in a C57BL/6 mouse model. Two 15-mm wide circular skin excisions were made on the backs of mice and to each excision, 100 µM A7-1 or normal saline was applied daily. The treatments were applied and sutured for skin graft analysis. Digital photos were acquired on days 4, 7, 11, and 14 and fluorescein angiography was conducted. Wound sizes were verified using stereoscopic microscopy. Histological analysis was performed via hematoxylin and eosin staining and Masson’s trichrome staining. Western blotting was performed using vascular endothelial growth factor. Using a stereoscopic microscope, significantly faster wound healing (17.3%) and skin graft healing (16.5%) were observed in the A7-1 treatment group in comparison to that of the control. The angiogenesis was significantly faster in fluorescein angiography examination in wound healing (11%) and skin grafts (15%). However, the average completion of epithelization (overall time for wound healing), did not show any significant differences. In comparison to the control, the new protein, A7-1, led to significantly faster wound healing in the initial angiogenesis.

Failure of soft materials is a fundamental challenge due to the strongly nonlinear and dissipative deformation involved. An experimental and extended finite element study of dynamic crack in silicone rubber are investigated. Hence, material preparation procedures, details of sample as well as testing apparatus which have been used for cutting, pure shear tests are presented. First, the rate of energy restitution and an instantaneous propagation speed were achieved. The crack propagation speed / energy release rate relationships are given for the different strain rates. second, an analysis of the mechanical fields and stress state in the fracture process zone is proposed. Finally, cutting force evolution according to stretches is established. Then, an energy-based approach was introduced. Results show that the cutting force and the total cutting energy decreases significantly with increasing deformation rate.

In waste heat recovery from a heavy-duty diesel engine, with a focus on engine speed's impact, is explored. The critical problem of enhancing energy efficiency and reducing emissions through waste heat utilization is addressed. Waste heat in internal combustion engines, vital for sustainable energy use and environmental preservation, is investigated. Experimental analysis and thermodynamic modeling introduce Organic Rankine Cycle (ORC), Steam Rankine Cycle (SRC), and Combined Steam and Organic Rankine Cycle (CSO) for waste heat recovery. A non-linear relationship between engine speed and waste heat is identified. Waste heat increases up to 1600 rpm and decreases thereafter. The CSO cycle outperforms ORC and SRC cycles, achieving 43.4% higher efficiency. Fuel energy savings demonstrate CSO's superior economy, along with excellence in Annual Carbon Dioxide Emissions Reduction (ACO2ER). Waste heat recovery knowledge is advanced by introducing the efficient CSO cycle, contributing significantly to existing research.

In this paper, an axial flux permanent magnet generator for a 30 kW direct drive wind turbine is designed and the design parameters were optimized with the aim of achieving high efficiency. In order to reduce the cogging torque and electromagnetic torque ripple components, the air core topology has been used, and with the aim of increasing the power capacity of the generator, a modular structure has been used. The advantage of the modular design is that each module can be considered as a generator unit and depending on the wind speed conditions, the number of units corresponding to the wind speed can be placed in the circuit and the generator will always work with maximum efficiency. First, by using the governing equations, the dimensions and performance characteristics of the generator are determined, and then a generator prototype is fabricated based on the electromagnetic design. In order to evaluate the output performance of the generator, machine simulation was performed in Maxwell finite element analysis software and the characteristic curves of voltage, current and ohmic losses were extracted. In order to evaluate the accuracy of the results, the outcomes of the analytical method have been compared with the experimental tests results.

In this paper, the similarity criterion and dimensionless conversion method combined with the elasticity condition and Hooke's law are used to derive the functional relationship of the maximum effective value of the vibration velocity between the prototype pump and the model pump. The seawater circulation pump of a nuclear power plant is used as the prototype pump, and the model pump is obtained by performance conversion and choosing the appropriate scale, and the vibration state of the model pump under different flow rates is measured and analyzed. The vibration data of the model pump through the function relationship to find out the vibration parameters of the prototype model pump, and compare with the vibration data of the seawater circulation pump in reality. It can be seen that with the increase of flow rate, the maximum effective value of the vibration velocity of both model and prototype decreases and then increases, and the relative error is small, the maximum value is 7.7757%. Therefore, it can be considered that the functional relationship of model pump converted to prototype pump derived in this paper can be used to analyze the vibration of the actual seawater circulation pump of coastal nuclear power plant.

Music is often regarded as the 'language of the emotions' (Cooke, 1995), and since the early 20th century, empirical research into musical emotions has been conducted to explore the mystery of how they are evoked by music. In this context, Frank et al. presented an experimental study that examined the scarcely researched field of historical listening. Their study aimed to investigate the question, "Do modern listeners hear the emotional content in Baroque music that the composer intended to portray?". The results indicated that modern listeners placed the three modern excerpts in the expected quadrants of the valence-arousal space. However, there were significantly different valence and arousal ratings among the Baroque examples and the modern excerpts, and significant differences between paired examples (where Baroque and modern examples were expected to fall into the same quadrants) occurred. This commentary summarizes Frank et al.'s experimental study, discusses methodological considerations, and suggests possible refinements for future (experimental) studies on historical listening.

In today's world, research on cooling systems that can effectively reduce the cooling time of heat sinks and enhance heat transfer efficiency in a shorter duration is extremely crucial. This experimental study analyzed the cooling time by simultaneously utilizing two cooling techniques. This involved the passage of ferrofluid (Fe3O4/water) through three channels of a heat sink under the influence of a magnetic field, as well as the application of an air impingement jet on the heat sink's surface. A novel plate-fin heat sink with dimensions of 40 mm (L) × 31.32 mm (W) × 23.5 mm (H) consists of three channels with a diameter of 3 mm for crossing ferrofluid flow and 24 channels on the top of the heat sink for crossing the air was designed and built for the study. The heat sink was exposed to an air impingement jet and an external magnetic field simultaneously. Multiple tests were conducted to determine the convective heat transfer coefficients of the heat sink over time under specific conditions, including a magnetic field of 800 G, a volume fraction of 3%, a Reynolds number of 600 for the ferrofluid, and a mass flow rate of 0.1 kg/s. It was discovered that using the combined method of magnetic field and impingement jet (MF-IJ) compared to cooling by air impingement jet with the simultaneous passage of pure water through the ferrofluid channels (Water-IJ), as well as the ferrofluid flow under a magnetic field without the impingement jet (MF) methods for the designed heat sink, can increase the maximum heat transfer coefficient by 27.4% and 46.4%, respectively. The findings of this study suggest that using the MF-IJ cooling method as a flow control mechanism, along with this innovative geometry, can reduce the cooling time of the heat sinks. [ABSTRACT FROM AUTHOR]

Concrete is obviously affected by the loading strain rate, and concrete exists in the state of shear multiaxial stress in practical engineering. Studying the dynamic response of concrete under multiaxial shear states facilitates comprehensive analysis of its actual failure behavior under complex loading conditions, thereby establishing an experimental foundation for precisely formulating dynamic constitutive models of concrete. Therefore, in this study, five axial compression ratios (0, 0.138, 0.207, 0.276, and 0.414 fc) and four strain rates (10−5/s , 10−4/s , 10−3/s , and 10−2/s) were considered. A servohydraulic machine for compression and shear was applied to conduct experimental research on the shear multiaxial dynamic mechanical properties of concrete. Different failure patterns and shear mechanical characteristic values of concrete under different loading conditions were obtained from the experiments. The following conclusions were mainly drawn through comparative analysis: as the axial compression ratio increases, oblique cracks are gradually formed in the parallel shear direction of the concrete, accompanied by a small amount of concrete spalling. The strain rate parameter has no significant influence on the apparent failure pattern of concrete in the parallel shear direction; moreover, as the axial compression ratio increases, the ranges of increase in shear stress and residual stress for concrete under different strain rates are 357.02% to 291.65%. The increase of strain rate gradually leads to a decreasing trend of shear stress for concrete under the influence of the axial compression ratio; as the strain rate increases, the range of increase in shear stress for concrete under different axial compression ratios is 21.08% to 33.81%. Overall, the increase of axial compression ratio leads to a decreasing trend of shear stress for concrete under the influence of strain rate. Based on the compression-shear relation and the principal stress space, the combined dynamic failure criterion of plain concrete is proposed by considering the effect of strain rate, and the corresponding stress mechanism is analyzed. The research results are of great significance to the development and application of concrete engineering. [ABSTRACT FROM AUTHOR]

In the present era, sedimentation and bed morphology near hydraulic structures is a great concern as it affects the flow configuration and reduces the discharge capacity. Experimental investigations were done to study the flow field in the vicinity of one cycle, two cycle, and three cycle piano key weirs (PK weirs) with noses to monitor the sediment passing capacity of the weir. The three dimensional (3D) velocities were measured close to the inlet and outlet keys using an acoustic Doppler velocimeter (ADV). The velocity fields near both the inlet and outlet keys were examined, and it was found that there were considerable increases in the vertical (v -component) and lateral (w -component) velocities. Added to this, it was seen that the mean vertical velocity was more in front of the outlet key as compared to the front of the inlet key while the mean lateral and longitudinal velocities were low. The maximum velocity was observed in front of the inlet key which resulted in an increase of sediment movement over the PK weir. Furthermore, 2.6%–5.2% of the total sediment passing over the upstream portion of the weirs are flushed over the inlet key by self-cleaning. The flow field over the keys could not be accurately estimated using an ADV, possibly due to the flow complexity so computational fluid dynamics (CFD) simulations were done to understand the complex flow field for all the three PK weirs using a CFD solver which needs less computational cost and space. The widely used standard k – ε turbulence model (an eddy-viscosity model) was applied in the current numerical investigations. The numerical investigation shows that the magnitude of the velocity components was increased because of the vertical contraction in front of the sloped keys owing to very high flow immediately downstream of PK weirs. [ABSTRACT FROM AUTHOR]

Throughout much of the 20th century, Sn–Pb solder dominated electronics. However, environmental and health concerns have driven the adoption of lead-free alternatives. Since 2006, legislation such as the European Union's RoHS Directive has mandated lead-free solder in most electronic devices, prompting extensive research into high-performance substitutes. Lead-free solders offer advantages such as reduced environmental impact and improved reliability but replacing Sn–Pb presents challenges in areas like melting point and wetting ability. This transition is primarily motivated by a focus on protecting environmental and human health, while ensuring equal or even improved reliability. Research has explored lead-free solder's mechanical properties, microstructure, wettability, and reliability. However, there is a notable lack of studies on its long-term performance and lifetime influence. To address this gap, mathematical models are used to predict intermetallic bond evolution from process conditions, validated with experimental tests. This study contributes by extending these models to predict bond evolution under typical operating conditions of devices and comparing the predictions with actual intermetallic thickness values found through metallographic sections. [ABSTRACT FROM AUTHOR]

This study employed nano-indentation technology, molecular dynamics simulation, and experimental investigation to examine the stress relaxation behaviour of a polycrystalline γ-TiAl alloy. The simulation enabled the generation of a load-time curve, the visualisation of internal defect evolution, and the mapping of stress distribution across each grain during the stress relaxation stage. The findings indicate that the load remains stable following an initial decline, thereby elucidating the underlying mechanism of load change during stress relaxation. Furthermore, a nano-indentation test was conducted on the alloy, providing insight into the load variation and stress relaxation behaviour under different loading conditions. By comparing the simulation and experimental results, this study aims to guide the theoretical research and practical application of γ-TiAl alloys. [ABSTRACT FROM AUTHOR]

Simple Summary: In this study, an experimental investigation was conducted to assess the pathogenicity of Babesia aktasi in immune-suppressed sheep. For this purpose, five immune-suppressed lambs under one year of age were infected by intravenous injection of fresh blood containing approximately 9.2% and 12% parasitemia of B. aktasi. Following parasite injection, the lambs were monitored daily for clinical and microscopic findings of babesiosis for 30 days. Throughout this period, no clinical and microscopic signs of babesiosis were observed in the lambs. Of the five recipient lambs, two tested negative for B. aktasi in nested PCR up to 30 days post-infection. Among the remaining three lambs, two were PCR positive on the first day, and the other one remained positive until the fourth day post-infection. DNA sequencing confirmed that the PCR positivity in the recipient lambs originated from the inoculum. These findings indicate that immune-suppressed lambs do not appear to be susceptible to infection with B. aktasi, which is highly pathogenic to immune-suppressed indigenous goats. Our survey in the Mediterranean region of Türkiye revealed high prevalence of Babesia aktasi in goats, while no molecular evidence of the parasite was found in sheep grazing in the same pasture. We hypothesized that the parasite may not be infectious to sheep. To test this hypothesis, the present study was designed to evaluate the susceptibility of Akkaraman sheep breed to B. aktasi infection. Fifteen mL of fresh blood infected with B. aktasi was injected into immune-suppressed lambs (n = 5). The recipient lambs were monitored daily for clinical signs of babesiosis over 30 days, and blood was collected for microscopic and molecular diagnostic evaluation. The lambs did not display clinical and parasitological signs of babesiosis. Two out of five recipient lambs were nested PCR-negative for B. aktasi over 30 days post infection. Out of the remaining three lambs, two were PCR positive on the first day, and one recipient was positive until the fourth day post infection. DNA sequencing confirmed that the PCR positivity in the recipient lambs originated from the inoculum. These findings revealed that immune-suppressed sheep do not appear to be susceptible to infection with B. aktasi that is lethal to immune-suppressed indigenous goats. [ABSTRACT FROM AUTHOR]

The effects of the novel synthetic peptide, A7-1, on wound healing and skin grafts were evaluated in a C57BL/6 mouse model. Two 15-mm wide circular skin excisions were made on the backs of mice and to each excision, 100 µM A7-1 or normal saline was applied daily. The treatments were applied and sutured for skin graft analysis. Digital photos were acquired on days 4, 7, 11, and 14 and fluorescein angiography was conducted. Wound sizes were verified using stereoscopic microscopy. Histological analysis was performed via hematoxylin and eosin staining and Masson's trichrome staining. Western blotting was performed using vascular endothelial growth factor. Using a stereoscopic microscope, significantly faster wound healing (17.3%) and skin graft healing (16.5%) were observed in the A7-1 treatment group in comparison to that of the control. The angiogenesis was significantly faster in fluorescein angiography examination in wound healing (11%) and skin grafts (15%). However, the average completion of epithelization (overall time for wound healing), did not show any significant differences. In comparison to the control, the new protein, A7-1, led to significantly faster wound healing in the initial angiogenesis. [ABSTRACT FROM AUTHOR]

In this paper, structural columns with cross-section sizes of 100 mm × 100 mm, 75 mm × 150 mm, and 85 mm × 121 mm are designed based on the same notional size of member. The acceleration signals of each column at axial compression ratio of 0.1, 0.2 and 0.3 were obtained by impact hammering. The corresponding frequency and damping ratio are obtained by half power wideband method. Based on the statistical method, the variation rules of acceleration signal characteristics, frequency characteristics and damping characteristics in different thickness directions under different axial compression ratios were analyzed. The correlation between frequency and damping ratio in different thickness directions with different axial compression ratios is discussed. The results show that under the same axial compression ratio, the damping ratio and frequency tend to decrease with the increase of the thickness in the tapping direction. Under the same thickness, the frequency decreases with the increase of the axial compression ratio. The damping ratio of the column decreases with increasing stress ratio when the thickness in the knocking direction is less than 100 mm. The damping ratio of the column increases with the increasing stress ratio when the thickness in the knocking direction is equal to 100 mm. The damping ratio of the column increases slightly with the increasing stress ratio when the thickness in the knocking direction is greater than 100 mm. By fitting the discrete data, the frequency variation range is 229.65–511.07 Hz, and the range of the damping ratio variation is 0.1–0.5%. [ABSTRACT FROM AUTHOR]

Estimating singular pressure losses for multi-stage obstacles in pressurized hydraulic ducts is a challenging task. An experimental study was conducted in a closed-loop hydrodynamic tunnel to characterize the pressure losses of a system consisting of a porous fibrous foam placed in front of a bar rack. The pressure losses of different foam–rack configurations were measured over a range of inlet velocities in order to highlight the mutual influence of their characteristics on the flow. The interdependence between the two stages has been evidenced by both the experimental results and additional numerical simulations using RANS (Reynolds-Averaged Navier–Stokes Equations) simulations with a k- ω SST turbulent closure model. The pressure losses were first modeled using two approaches based on the assumption of either independence or full dependence between the stages. The respective advantages and limitations of these approaches led to an improved analytical formula that considers the transition of the flow from the porous foam to the bar rack. By taking into account an empirical transition factor, the proposed model improves the head loss prediction for all tested configurations, with an average relative error between the formula and experimental results less than that of the two simpler approaches. This study improves our understanding of global pressure losses in multi-stage systems that include a porous foam or other filtering or clogging media in front of bar racks. [ABSTRACT FROM AUTHOR]

The food crisis has increased demand for agricultural resources due to various factors such as extreme weather, energy crises, and conflicts. A solar greenhouse enables counter-seasonal winter cultivation due to its thermal insulation, thus alleviating the food crisis. The root temperature is of critical importance, although the mechanism of soil thermal environment change remains uncertain. This paper presents a comprehensive study of the soil thermal environment of a solar greenhouse in Jinzhong City, Shanxi Province, employing a variety of analytical techniques, including theoretical, experimental, and numerical simulation, and deep learning modelling. The results of this study demonstrate the following: During the overwintering period, the thermal environment of the solar greenhouse floor was divided into a low-temperature zone, a constant-temperature zone, and a high-temperature zone; the distance between the low-temperature boundary and the southern foot was 2.6 m. The lowest temperature in the low-temperature zone was 11.06 °C and the highest was 19.05 °C. The floor in the low-temperature zone had to be heated; the lowest value of the constant-temperature zone was 18.29 °C, without heating. The minimum distance between the area of high temperature and the southern foot of the solar greenhouse was 8 m and the lowest temperature reading was 19.29 °C. The indoor soil temperature tended to stabilise at a depth of 45 cm, and the lowest temperature reading at a horizontal distance of 1400 mm from the south foot was 19.5 °C. The Fluent and LSTM models fitted well and the models can be used to help control soil temperature during overwintering in extreme climates. The research can provide theoretical and data support for the crop areas and the heating of pipelines in the solar greenhouse. [ABSTRACT FROM AUTHOR]

Background: Improving walking ability is a key objective in the treatment of children and adolescents with cerebral palsy, since it directly affects their activity and participation. In recent years, robotic technology has been implemented in gait treatment, which allows training of longer duration and repetition of the movement. To know the effectiveness of a treatment with the robotic-assisted gait trainer Walkbot combined with physiotherapy compared to the isolated physiotherapy treatment in children and adolescents with cerebral palsy, we carried out a clinical trial. Methods: 23 participants, were divided into two groups: experimental and control. During 5 weeks, both groups received their physiotherapy sessions scheduled, in addition experimental group received 4 sessions per week of 40 min of robot. An evaluation of the participants was carried out before the intervention, at the end of the intervention, and at follow-up (two months after the end of the intervention). Gait was assessed with the Gross Motor Function Measure-88 dimensions D and E, strength was measured with a hydraulic dynamometer, and range of motion was assessed using the goniometer. A mixed ANOVA was performed when the assumptions of normality and homoscedasticity were met, and a robust mixed ANOVA was performed when these assumptions were not met. Statistical significance was stipulated at p < 0.05. For the effect size, η2 was calculated. Results: Significant differences were found regarding the time x group interaction in the Gross Motor Function Measure-88 in dimension D [η2 = 0.016], in the flexion strength of the left [η2 = 0.128] and right [η2 = 0.142] hips, in the extension strength of the right hip [η2 = 0.035], in the abduction strength of the left hip [η2 = 0.179] and right [η2 = 0.196], in the flexion strength of the left knee [η2 = 0.222] and right [η2 = 0.147], and in the range of motion of left [η2 = 0.071] and right [η2 = 0.053] knee flexion. Conclusions: Compared to treatments without walking robot, physiotherapy treatment including Walkbot improves standing, muscle strength, and knee range of motion in children and adolescents with cerebral palsy. Trial registration: ClinicalTrials.gov: NCT04329793. First posted: April 1, 2020. [ABSTRACT FROM AUTHOR]

The contents of alkali and alkaline earth metals are higher in Zhundong coal, and there are serious problems of slagging and fouling during the combustion process. Therefore, it is of great significance to reveal the mechanism of slagging and fouling in the boiler of Zhundong coal. In this paper, first-principle calculations based on density functional theory are used to study the competition mechanism of alkaline metal oxides during the combustion process in Zhundong coal by establishing the Na2O(110)/CaO(100)-SiO2(100) double-layer interface model. The results show that the bond lengths of the surface of Na2O(110) and CaO(100) with SiO2(100) after adsorption were generally lengthened and the value of bond population became smaller, which formed a stable binding energy during the reaction. The electron loss of Na is 0.05 e, the electron loss of Ca is 0.03 e, and the electron loss of Na2O is greater than that of CaO. The charge transfer on the surface of Na2O with SiO2 is obviously higher than that of CaO and the orbital hybridization on the surface of CaO with SiO2 is weaker than that on the surfaces of Na2O with SiO2. Na2O is easier to react with SiO2 than CaO. The adsorption energies on the surface of Na2O and CaO with SiO2 are −5.56 eV and −0.72 eV, respectively. The adsorption energy of Na2O is higher than that of CaO, indicating that Na2O is more prone to adsorption reactions and formation of Na-containing minerals and other minerals, resulting in more serious slagging. In addition, the XRD analyses at different temperatures showed that Na-containing compounds appeared before Ca-containing ones, and the reaction activity of Na2O is stronger than that of CaO in the reaction process. The experimental results have good agreement with the calculation results. This provides strong evidence to reveal the slagging and fouling of Zhundong coal. [ABSTRACT FROM AUTHOR]

In order to reveal the mechanism of sleeved stud connectors, 15 push-out specimens were designed, and static loading tests were conducted to evaluate the mechanical performance. The shear performance differences between the novel sleeved studs and conventional welded studs were compared. Referring to the experimental results, an Abaqus nonlinear finite element model was established to study the shear mechanism of sleeved stud connectors. Parametric analysis was conducted to investigate the effects of stud height, sleeve filling material, and sleeve diameter on the mechanical performance of the connectors. The experimental and finite element analysis results indicated that the ultimate shear bearing capacity and shear stiffness of the sleeved stud connectors were higher than those of ordinary welded studs, and the maximum slip was relatively small. Compared to conventional welded studs, the ultimate bearing capacity of sleeved studs increased by 4% to 8%, and the shear stiffness increased by 25% to 35%. Since the shear behavior of sleeved studs mainly occurred at the base of the studs, the influence of stud height on shear performance was relatively small. However, sleeve and stud diameter have a great influence on bearing capacity and stiffness. As the Ultra-High Performance Concrete (UHPC) near the base of the stud effectively enhanced the shear carrying capacity of the sleeved stud connectors, the shear carrying capacity and shear stiffness increased with the increase in the sleeve diameter. [ABSTRACT FROM AUTHOR]

New results of experimental study of the process of rise of a spherically shaped group of monodisperse bubbles in the presence of a surfactant in the region of Reynolds numbers Re = 200–600 have been presented. The influence of the nature of a surfactant on the dynamics of rise of the group of bubbles has been analyzed. Experimental data have been obtained on the trajectory of rise of bubbles forming the group depending on the type of surfactant in the liquid. The authors were the first to obtain experimental data on the velocity and the coefficient of resistance of a group of monodisperse bubbles rising in the presence of different surfactants. Criterial dependences have been obtained for dimensionless velocity of rise of a group of monodisperse bubbles as a function of the type of surfactant in the liquid. [ABSTRACT FROM AUTHOR]

Introduction: Contrary to the traditional recognition that CO2 has large injectivity (the ratio of CO2 injection volume to pressure drop) in low permeability oil reservoirs to keep the formation pressure at a high level, the CO2 injection rate usually cannot attain the set value. It is essential to study the factors that influence CO2 injectivity and propose the optimal strategies to improve the CO2 injectivity. Methods: Therefore, in this study, several core samples collected from low permeability oil reservoirs are used to experimentally investigate the influences of CO2 injection rate, formation permeability, pressure and water saturation on CO2 injectivity, and the corresponding pressure drop, oil and gas production are examined. To determine the primary factor that influences the CO2 injectivity, orthogonal experimental design (ODE) and numerical simulations are utilized. In addition, to improve CO2 injectivity, the techniques of mini-fracturing and radial perforation are presented, and the threshold values for these two parameters are determined. Result and discussion: The results demonstrate that according to the magnitude of the extent that influences CO2 injectivity, the rank for the above factors is CO2 injection rate, reservoir pressure, formation water saturation and permeability. The oil recovery is mainly influenced by CO2 injection rate and formation permeability, and the influences of reservoir pressure and water saturation on oil recovery are smaller. The threshold values for radial perforation and fracture half-length are 25 m and 50m, respectively, which can provide some guidance for the strategies that should be taken to improve the CO2 injectivity and recover more oil from low permeability oil reservoirs. [ABSTRACT FROM AUTHOR]

Failure of soft materials is a fundamental challenge due to the strongly nonlinear and dissipative deformation involved. An experimental and extended finite element study of dynamic crack in silicone rubber are investigated. Hence, material preparation procedures, details of sample as well as testing apparatus which have been used for cutting, pure shear tests are presented. First, the rate of energy restitution and an instantaneous propagation speed were achieved. The crack propagation speed / energy release rate relationships are given for the different strain rates. second, an analysis of the mechanical fields and stress state in the fracture process zone is proposed. Finally, cutting force evolution according to stretches is established. Then, an energybased approach was introduced. Results show that the cutting force and the total cutting energy decreases significantly with increasing deformation rate. [ABSTRACT FROM AUTHOR]

The article is devoted to the study of the connecting cable influence, as an element with distributed parameters between the pulsed generator and discharge chamber in the electrical complex based on pulsed barrier discharge, to the values of currents and voltages in the system. Based on experimental studies and modeling, it has been established that the currents at different ends of the cable differ significantly from each other, which is due to the large value capacitive pulsed charging current of the cable. It has been established that during the barrier discharge, a correctly measured pulse current has significantly shorter duration than pulse of voltage. During the electrical discharge, a feature of the dependence of the current at the input to the cable is the appearance of an additional local maximum, of much smaller amplitude with a time shift equal to the time the electromagnetic wave movement along the cable. It has been shown that the use of the connecting cable of increased length makes it possible to increase the voltage between the electrodes of two times in comparison with the voltage at the cable input, without taking into account the voltage drop across the internal resistance of the generator when the cable length no less than twice the path length that the electromagnetic wave moves during the time from start of the pulse to maximum value generator pulse. References 16, figures 7. [ABSTRACT FROM AUTHOR]

Mechanism analysis and technical scheme optimization on CO2 displacement and CO2 storage are based on the high-pressure physical properties of CO2-added formation oil. Oil and natural gas samples from the BZ25-1 block in the Bohai oilfield were used to conduct high-pressure physical property experiments to explore the impacts of CO2-CH4 mixed gas on the properties of formation oil. After injecting different amounts of mixed gas, the saturated pressure was measured by constant mass expansion test, the viscosity was measured by falling ball method, the expansion coefficient was measured by gas injection expansion test, and the gas–oil ratio and volume coefficient were obtained by single degassing test. The results show that with gas injection, the saturation pressure and dissolved gas–oil ratio of formation oil increase, the volume coefficient and expansion factor go up, while the oil viscosity reduces. With the increase in gas addition, the properties of formation oil continue to improve, but the increase in improvement becomes flat. With the increase in pressure, the amount of dissolved gas in the formation oil will also increase. High-purity CO2 is more helpful to change the properties of formation oil, while the gas mixed with CH4 is more beneficial to elevate the formation energy. For the BZ 25-1 block, the gas injection amount of about 80 mol% is appropriate and the CO2 purity of 60% can well balance the oil properties improvement and the formation pressure elevation. [ABSTRACT FROM AUTHOR]