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Collective idea generation and innovation processes are complex and dynamic, involving a large amount of qualitative narrative information that is difficult to monitor, analyze, and visualize using traditional methods. In this study, we developed three new visualization methods for collective idea generation and innovation processes and applied them to data from online social network experiments. The first visualization is the Idea Cloud, which helps monitor collective idea posting activity and intuitively tracks idea clustering and transition. The second visualization is the Idea Geography, which helps understand how the idea space and its utility landscape are structured and how collaboration was performed in that space. The third visualization is the Idea Network, which connects idea dynamics with the social structure of the people who generated them, displaying how social influence among neighbors may have affected collaborative activities and where innovative ideas arose and spread in the social network.

BACKGROUND Adverse childhood experiences (ACEs), which include abuse and neglect and various household challenges such as exposure to intimate partner violence and substance use in the home, can have negative impacts on the lifelong health of affected individuals. Among various strategies for mitigating the adverse effects of ACEs is to enhance connectedness and social support for those who have experienced them. However, how the social networks of those who experienced ACEs differ from the social networks of those who did not is poorly understood. OBJECTIVE In this study, we used Reddit and Twitter data to investigate and compare social networks between individuals with and without ACE exposure. METHODS We first used a neural network classifier to identify the presence or absence of public ACE disclosures in social media posts. We then analyzed egocentric social networks comparing individuals with self-reported ACEs with those with no reported history. RESULTS We found that, although individuals reporting ACEs had fewer total followers in web-based social networks, they had higher reciprocity in following behavior (ie, mutual following with other users), a higher tendency to follow and be followed by other individuals with ACEs, and a higher tendency to follow back individuals with ACEs rather than individuals without ACEs. CONCLUSIONS These results imply that individuals with ACEs may try to actively connect with others who have similar previous traumatic experiences as a positive connection and coping strategy. Supportive interpersonal connections on the web for individuals with ACEs appear to be a prevalent behavior and may be a way to enhance social connectedness and resilience in those who have experienced ACEs.

Adverse childhood experiences (ACEs), which include abuse and neglect and various household challenges like exposure to intimate partner violence and substance use in the home can have negative impacts on lifelong health of affected individuals. Among various strategies for mitigating the adverse effects of ACEs is to enhance connectedness and social support for those who have experienced ACEs. However, how social networks of those who experienced ACEs differ from those who did not is poorly understood. In the present study, we use Reddit and Twitter data to investigate and compare social networks among individuals with and without ACEs exposure. We first use a neural network classifier to identify the presence or absence of public ACEs disclosures in social media posts. We then analyze egocentric social networks comparing individuals with self-reported ACEs to those with no reported history. We found that, although individuals reporting ACEs had fewer total followers in online social networks, they had higher reciprocity in following behavior (i.e., mutual following with other users), a higher tendency to follow and be followed by other individuals with ACEs, and a higher tendency to follow back individuals with ACEs rather than individuals without ACEs. These results imply that individuals with ACEs may try to actively connect to others having similar prior traumatic experiences as a positive connection and coping strategy. Supportive interpersonal connections online for individuals with ACEs appear to be a prevalent behavior and may be a way to enhance social connectedness and resilience in those who have experienced ACEs.

New modes of transportation systems are under intensive development because traditional systems fail to become mass transportation means due to their technological limitations. To meet the growing ...

In the design stage of an aircraft, structural analyses are commonly employed to test the integrity of the aircraft components to demonstrate the capability of the structural elements to withstand what they are designed for, as well as predict potential failure of the components. This research focused on the structural design and analysis of a high-lift, low Reynolds number airfoil profile, the Selig S1223, under reciprocating inertial force loading, to determine the feasibility of its use in a new reciprocating airfoil (RA) driven VTOL UAV. The material selected for the wing structures including ribs, spars, and skin, was high-strength carbon fiber. The wing was designed in SolidWorks, while finite element analysis was performed with ANSYS mechanical in conjunction with the inertia forces due to the reciprocating motion of the wing and the lift and drag forces that were derived from the aerodynamic wing analyses. The structural stress and strain determined under the loading conditions were satisfactory and the designed wing could sustain the high reciprocating inertia forces in the RA-driven VTOL UAV module. The results of this study indicate that the Selig S1223 airfoil profile, due to its superior performance at low Reynolds numbers, high-lift, and reduced noise characteristics at low angles of attack, combined with the use of the high strength carbon fiber, proves to be an excellent choice for this RA-driven aircraft application.

Collective design and innovation are crucial in organizations. To investigate how the collective design and innovation processes would be affected by the diversity of knowledge and background of collective individual members, we conducted three collaborative design task experiments which involved nearly 300 participants who worked together anonymously in a social network structure using a custom-made computer-mediated collaboration platform. We compared the idea generation activity among three different background distribution conditions (clustered, random, and dispersed) with the help of the “doc2vec” text representation machine learning algorithm. We also developed a new method called “Idea Geography” to visualize the idea utility terrain on a 2D problem domain. The results showed that groups with random background allocation tended to produce the best design idea with the highest utility values. It was also suggested that the diversity of participants’ backgrounds distribution on the network might interact with each other to affect the diversity of ideas generated. The proposed idea geography successfully visualized that the collective design processes did find the high utility area through exploration and exploitation in collaborative work.

Leaders are often identified in empirical studies by either their position in an organizationally defined hierarchy or by survey responses, yet such methods conflate behavioral antecedents and outcomes with behaviors themselves. Furthermore, without an external standard for comparison, it cannot be known to what extent differences in leader assignment or emergence between demographic or other categories are due to behavioral differences or biases in the assessment, selection, training, or rating processes. In this study, we propose the ``interruption network'' as a model of small group structure that is (a) grounded in social status theory, (b) definable in both lab and field groups, (c) minimally impacted by rater bias, and (d) based on assessed behaviors rather than antecedents or outcomes. We show that analysis of interruption networks suggests that the often-reported male bias in leadership attributions is found in the ratings but not in the behavior of the observed individuals: males and females may engage in leadership behaviors equally as often, but males are attributed leadership significantly more. Use of the interruption network to represent small group social status therefore extends well-established research on non-verbal behaviors to an explicitly group-oriented context, supporting theory-based unobtrusive assessment and new ways to address important questions in applied psychology.

Effective teamwork in an initially leaderless group requires a high level of collective leadership emerging from dynamic interactions among group members. Leader emergence is a crucial topic in collective leadership, yet it is challenging to investigate as the problem context is typically highly complex and dynamic. Here, we explore leadership emergence and leadership perception by means of computational simulations whose assumptions and parameters were informed by empirical research and human-subject experiments. Our agent-based model describes the process of group planning. Each agent is assigned with three key attributes: talkativeness, intelligence, and credibility. An agent can propose a suggestion to modify the group plan as a speaker or respond and evaluate others’ suggestions and leadership as a listener. Simulation results suggested that agents with high values of talkativeness, intelligence, and credibility tended to be perceived as leaders by their peers. Results also showed that talkativeness may be the most significant and instantaneous predictor for leader emergence of the three investigated attributes: talkativeness, intelligence, and credibility. In terms of group performance, smaller groups may outperform larger groups regarding their problem-solving ability in the beginning, but their performance tends to be of no significant difference in a long run. These results match the empirical literature and offer a mechanistic, operationalized description of the collective leadership processes.

Conversational interruptions can carry negative connotations, yet prior research has consistently found positive associations between interruptions and attributions of leadership and social status....

A bellows-type Reciprocating-Mechanism Driven Heat Loops (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the working fluid inside the heat transfer device. Although the device has been tested and validated experimentally, analytical or numerical study has not been undertaken to understand its working mechanism and provide guidance for the device design. In an effort to improve earlier numerical models of the RMDHL, different turbulence models for the RMDHL design have been studied and compared with prior experimental results to select the most suitable turbulence modeling techniques. The governing equations have been numerically solved using a CFD solver. For the three-dimensional fluid flow, several turbulence models have been studied for the RMDHL, including Standard, RNG, and Realizable k-ɛ Models, Standard and SST k-ω Models, Transition k - k L -ω Model and the Transition SST Model. The results of the simulations have been analyzed and ranked using numerical model calibration template. It was found that the standard k-ω Models provided the least accurate results while the RNG-k-ɛ Model provided the most accurate predictions. It is expected that the results will help improve the accuracy of the work on the RMDHL modeling.

The large, positive correlation between speaking time and leader emergence is well-established. As such, some authors have argued for a “babble hypothesis” of leadership, suggesting that only the quantity of speaking, not its quality, determines leader emergence. However, previous tests of this notion may have been problematic. Some studies have asserted a causal effect of speaking time on leader emergence based on experimental studies, but have limited participant communication, access to reliable information, or both. Other studies have used more ecologically valid designs, but have not always controlled for relevant participant traits or roles, suggesting potential endogeneity effects. Testing the babble hypothesis thus requires a study that is both ecologically valid and supports strong inference. The current study fills that gap and finds that speaking time retains its direct effect on leader emergence when accounting for intelligence, personality, gender, and the endogeneity of speaking time.

In this study, the performance of a SBC (supercritical gas Brayton cycle) using CO2-based binary mixtures as the working fluids have been studied. Based on the thermodynamic analyses, an in-house code has been developed to determine the cycle efficiency and the amounts of heat transfer in the HTR (high temperature recuperator) and the LTR (low temperature recuperator) with different CO2/additive gas ratios. Several gases are selected as potential additives, including O2, He, Ar, Kr, butane and cyclohexane. Compared with the Brayton cycle with pure S–CO2 (supercritical carbon dioxide) as the working fluid, it is found that both CO2–He and CO2–Kr mixtures can improve the thermodynamic performances of the SBC by increasing the cycle efficiency and decreasing the amounts of heat transfer in the HTR and LTR. For the cycles with the pure S–CO2 mixture, CO2–butane mixture and CO2–cyclohexane mixture as the working fluids, the cycle efficiencies decrease with increasing main compressor inlet temperature. However, when the main compressor inlet temperature is above the critical temperature of pure CO2, the cycle efficiencies of the cycles with CO2–butane mixture and CO2–cyclohexane mixture are higher than that of the cycle with pure CO2 as the working fluid. For the cycles with CO2-based binary mixtures and pure S–CO2 as the working fluids, the higher reactor outlet temperature always results into higher cycle efficiencies and larger amount of heat transfer in the HTR and smaller amount of heat transfer in the LTR.

Thermoelectric (TE) generator converts heat to electric energy by thermoelectric material. However, heat removal on the cold side of the generator represents a serious challenge. To address this problem and for improved energy conversion, a thermoelectric generation process coupled with methanol steam reforming (SR) for hydrogen production is designed and analyzed in this paper. Experimental study on the cold spot character in a micro-reactor with monolayer catalyst bed is first carried out to understand the endothermic nature of the reforming as the thermoelectric cold side. A novel methanol steam reforming micro-reactor heated by waste heat or methanol catalytic combustion for hydrogen production coupled with a thermoelectric generation module is then simulated. Results show that the cold spot effect exists in the catalyst bed under all conditions, and the associated temperature difference first increases and then decreases with the inlet temperature. In the micro-reactor, the temperature difference between the reforming and heating channel outlets decreases rapidly with an increase in thermoelectric material's conductivity coefficient. However, methanol conversion at the reforming outlet is mainly affected by the reactor inlet temperature; while at the combustion outlet, it is mainly affected by the reactor inlet velocity. Due to the strong endothermic effect of the methanol steam reforming, heat supply of both kinds cannot balance the heat needed at reactor local areas, resulting in the cold spot at the reactor inlet. When the temperature difference between the thermoelectric module's hot and cold sides is 22 K, the generator can achieve an output voltage of 55 mV. The corresponding molar fraction of hydrogen can reach about 62.6%, which corresponds to methanol conversion rate of 72.6%.

SUMMARY The objectives of this paper are to introduce a new heat engine and evaluate its performance. The new heat engine uses a gas, such as air, nitrogen, or argon, as the working fluid and extracts thermal energy from a heat source as the energy input. The new heat engine may find extensive applications in renewable energy industries, such as concentrating solar power (CSP). Additionally, the heat engine may be employed to recover energy from exhaust streams of internal combustion engines, gas turbine engines, and various industrial processes. It may also work as a thermal-to-mechanical conversion system in a nuclear power plant and function as an external combustion engine in which the heat source is the combustion gas from an external combustion chamber. The heat engine is to mimic the performance of an air-standard Otto cycle. This is achieved by drastically increasing the time duration of heat acquisition from the heat source in conjunction with the timing of the heat acquisition and a large heat transfer surface area. Performance simulations show that the new heat engine can potentially attain a thermal efficiency above 50% and a power output above 100 kW under open-cycle operation. Additionally, the heat engine could significantly reduce CSP costs and operate in open cycles, effectively removing the difficulties of dry cooling requirement for CSP applications. Copyright © 2014 John Wiley & Sons, Ltd.

Heat pipe technology offers a possible cooling technique for structures exposed to high heat fluxes, as in turbomachinery such as compressors and turbines. However, in its current configuration as single heat pipes, implementation of the technology is limited due to the difficulties in manufacturability and costs. Hence, a study to develop a new radially rotating (RR) heat pipe system was undertaken, which integrates multiple RR heat pipes with a common reservoir and interconnected braches for a more effective and practical solution to turbomachinery cooling. Experimental study has shown that the integration of multiple heat pipe branches with a reservoir at the top is feasible.

An effective design option for a cooling system is to use a two-phase pumped cooling loop to simultaneously satisfy the temperature uniformity and high heat flux requirements. A reciprocating-mechanism driven heat loop (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the two-phase working fluid inside the heat transfer device. Although the device has been tested and validated experimentally, analytical or numerical study has not been undertaken to understand its working mechanism and provide guidance for the device design. The objective of this paper is to develop a numerical model for the RMDHL to predict its operational performance under different working conditions. The developed numerical model has been successfully validated by the existing experimental data and will provide a powerful tool for the design and performance optimization of future RMDHLs. The study also reveals that the maximum velocity in the flow occurs near the wall rather than at the center of the pipe, as in the case of unidirectional steady flow. This higher velocity near the wall may help to explain the enhanced heat transfer of an RMDHL.

A bellows-type Reciprocating-Mechanism Driven Heat Loops (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the working fluid inside the heat transfer device. Although the device has been tested and validated experimentally, analytical or numerical study have not been undertaken to understand its working mechanism and to provide guidance for the device design. In a bid to improve the accuracy of the numerical models of the RMDHL, seven turbulence models for fluid flow have been alternately adapted and implemented in an existing numerical RMDHL model. The obtained results were studied and compared with prior experimental results to gain confidence and select the most suitable turbulence modeling techniques. The Boussinesq approximation has been used and the governing equations have been numerically solved using the CFD solver FLUENT. For the three-dimensional fluid flow, the turbulence models were studied are the Standard, RNG, and Realizable k-ε Models, Standard and SST k-ω Models, Transition k-kL-ω Model and the Transition SST Model. The result of each numerical simulation have been analyzed and ranked using a numerical model calibration template. It was found that the standard k-ω Models provided the least accurate results while the RNG-k-ε Model provided the most accurate predictions. It is expected that the results will help improve the accuracy of the work on the RMDHL modeling.

SUMMARY The reciprocating-mechanism driven heat loop (RMDHL) is a novel two-phase heat transfer device that could find many important applications in energy systems and electronic cooling. However, the previous RMDHL is based on a solenoid driver that may have difficulty in handling a large amount of heat transfer rate over a long distance due to the driver's inability to provide a large displacement volume. To overcome this difficulty, a bellows-type RMDHL demonstration model has been designed, fabricated, and tested. The results show that the bellows-type RMDHL has successfully overcome the weakness of the solenoid driver and may be employed for applications involving large heat transfer rates and over a large surface area. Another advantage of the bellows-type RMDHL is its potential to maintain an exceedingly uniform temperature over a relatively large surface. Additionally, the power consumption of the bellows driver was less than 5 W when the power input to the cold plate was up to 600 W, resulting in the ratio of driver's power input to the heat input to the cold plate being less than 1%, which represents a tenfold improvement over the solenoid-based RMDHL. All these technical improvements over the previous RMDHL have demonstrated significant progresses towards a refined RMDHL system for energy and electronics cooling applications. Copyright © 2012 John Wiley & Sons, Ltd.

A new cold-start approach for internal combustion engines is described, which may be particularly suitable for an engine using an alternative fuel, such as ethanol or methanol. One of the cylinders in the engine may be equipped with a holding chamber in the cylinder head for the cold-start purpose. The holding chamber may be opened or closed by a holding chamber valve to establish or block the fluid flow between the holding chamber and the cylinder space. The cold-start procedure includes an intake stroke and a compression stroke, an expansion stroke that conserves the energy content of the earlier compressed charge without returning the compression work to the piston, and a subsequent recompression stroke to compress the charge to a much higher temperature. A thermodynamic analysis on the cold-start process of a homogeneous charge internal combustion engine is undertaken, which includes the effect of fuel vaporization on the temperature change of the charge during the first compression stroke. It is found that the charge could be compressed effectively to a sufficiently higher temperature for ignition with pure ethanol as fuel. Copyright © 2010 John Wiley & Sons, Ltd.

SUMMARY An internal-combustion engine platform, which may operate on a portfolio of cycles for an increased expansion ratio, combustion under constant volume, variable compression ratio, and cold start, is introduced. Through unique thermodynamic cycles, the engine may be able to operate on a much greater expansion ratio than the compression ratio for a significantly improved thermal efficiency. This improvement is attained without involving a complex mechanical structure or enlarged engine size, and at the same time without reducing the compression ratio. The engine with these features may serve as an alternative to the Atkinson cycle engine or the Miller cycle engine. Furthermore, based on the same engine platform, the engine may operate on other cycles according to the load conditions and environmental considerations. These cycles include those for combustion under constant volume, variable compression ratio under part load conditions, and cold start for alternative fuels. It is believed that the introduced thermodynamic cycles associated with the engine platform may enable a future internal combustion engine that could generally increase the thermal efficiency by about 20% under full and part load conditions and overcome the cold start problem associated with diesel fuels or alternative fuels such as ethanol and methanol. Copyright © 2011 John Wiley & Sons, Ltd.

The convection heat loss from cavity receiver in parabolic dish solar thermal power system can significantly reduce the efficiency and consequently the cost effectiveness of the system. It is important to assess this heat loss and subsequently improve the thermal performance of the receiver. This paper aims to present a comprehensive review and systematic summarization of the state of the art in the research and progress in this area. The efforts include the convection heat loss mechanism, experimental and numerical investigations on the cavity receivers with varied shapes that have been considered up to date, and the Nusselt number correlations developed for convection heat loss prediction as well as the wind effect. One of the most important features of this paper is that it has covered numerous cavity literatures encountered in various other engineering systems, such as those in electronic cooling devices and buildings. The studies related to those applications may provide valuable information for the solar receiver design, which may otherwise be ignored by a solar system designer. Finally, future development directions and the issues that need to be further investigated are also suggested. It is believed that this comprehensive review will be beneficial to the design, simulation, performance assessment and applications of the solar parabolic dish cavity receivers.

Three working-liquid charging methods for miniature heat pipes are introduced, and their advantages and disadvantages are described. The methods are referred to as the micro-syringe method, thermodynamic equilibrium method, and capillary-tubing method. Using these methods, two types of ceramic heat pipes were charged and tested. The ceramic heat pipes were made of alumina and have overall dimensions of 89 mm × 12 mm × 2.9 mm and a designed vapor space of 82.5 mm × 4.1 mm × 1.27 mm. Axial micro-capillary grooves were provided on the top and bottom or sidewalls inside the heat pipes as wick structures. Water was used as the working liquid. More than 20 W of heat input was achieved on a 5 mm × 5 mm heating surface. The corresponding heat flux was 80 W/cm2.

This paper proposes a parabolic dish/AMTEC solar thermal power system and evaluates its overall thermal–electric conversion performance. The system is a combined system in which a parabolic dish solar collector is cascaded with an alkali metal thermal to electric converter (AMTEC) through a coupling heat exchanger. A separate type heat-pipe receiver is selected to isothermally transfer the solar energy from the collector to the AMTEC. To assess the system’s overall thermal–electric conversion performance, a theoretical analysis has been undertaken in conjunction with a parametric investigation by varying relevant parameters, i.e., the average operating temperature and performance parameters associate with the dish collector and the AMTEC. Results show that the overall conversion efficiency of parabolic dish/AMTEC system could reach up to 20.6% with a power output of 18.54 kW corresponding to an operating temperature of 1280 K. Moreover, it is found that the optimal condenser temperature, corresponding to the maximum overall efficiency, is around 600 K. This study indicates that the parabolic dish/AMTEC solar power system exhibits a great potential and competitiveness over other solar dish/engine systems, and the proposed system is a viable solar thermal power system.

The alkali metal thermal to electric converter (AMTEC) is one of the most promising technologies for direct conversion of thermal energy to electricity and has been receiving attention in the field of energy conversion and utilization in the past several decades. This paper aims to present a comprehensive review of the state of the art in the research and development of the AMTEC, including its working principles and types, historical development and applications, analytical models, working fluids, electrode materials, as well as the performance and efficiency improvement. The current two major problems encountered by the AMTEC, the time-dependent power degradation and relatively low efficiency compared to its theoretical value, are discussed in depth. In addition, a brief comparison of the AMTEC with other direct thermal to electric converters (DTECs), such as the thermoelectrics converter (TEC), thermionics converter, and thermophotovoltaics converter, is given, and combinations of different DTECs to further improve DTECs' power generation and overall conversion efficiency are demonstrated. Future research and development directions and the issues that need to be further investigated are also suggested. It is believed that this comprehensive review will be beneficial to the design, simulation, analysis, performance assessment, and applications of various types of AMTECs. Copyright © 2009 John Wiley & Sons, Ltd.

This technical note describes the spontaneous liquid uplift in biliquid capillary siphons. It was found that, in general, liquids that have a low surface tension to wet the wick material and a low viscosity (methanol, etc.) could be spontaneously uplifted to liquids with a high surface tension (water, etc.) or high viscosity (glycerin, etc.) through a wick configured in a siphon fashion. An interpretation of the results using the liquid capillary rise equations is given.

The capillary siphon is a device capable of transporting a liquid from a higher level to a lower level by capillary action under gravity. The device is usually configured in an inverted U-shape with an intake end and a discharge end. However, to the authors’ knowledge, the prior arts have not disclosed a process or apparatus that utilizes the capillary siphon action to transfer a liquid into a different liquid from a lower level to a higher level. In this paper, a porous medium, which preferentially has a higher wickability with respect to the first liquid than to the second liquid, is disposed in a siphon fashion with the first or intake end contacting the first liquid and the second or discharge end contacting the second liquid. A net amount of the first liquid was observed to be pumped into the second liquid. The aforementioned novel device functions as a passive pump, and could find applications in many systems such as portable direct methanol fuel cells and drug delivery systems. The device with these potential applications is termed as the “biliquid capillary siphon”. The biliquid capillary siphon was successfully tested using several typical wick materials such as fiberglass, ceramic, polyethylene and PTFE under both dynamic and quasi-equilibrium states.