Trade-off Behavior Research Articles

Computational analysis on the electrode geometric parameters for the reversible solid oxide cells

Increasing global energy demands have been accelerating the research and development of reversible electrochemical systems that can realize an efficient use of the intermittent renewable energy resources. This paper thus describes a numerical investigation of reversible solid oxide cells (RSOCs), for their high energy efficiency delivered from the high operating temperatures ranging from 600 to 1000°C. Unlike the previous studies, a model-based strategy is applied for the simultaneous integration of different operating modes (namely, fuel cell and electrolysis cell modes) to enable more realistic predictions on the trade-off behavior of the effects of electrode design parameters on the cell performance. This approach was taken to investigate the effects of various geometric designs and operating parameters (electrode backing layer thickness; interconnector rib size; fuel gas composition) on the current-potential characteristic and the round-trip efficiency. The cell performance was significantly affected by the rib size, particularly when the backing layer was thin, because of the uneven distribution of the reactant species. Overall, this study provides insights into key geometric design parameters that dominate the performance of dual-mode RSOCs.

The Role of Barrier Transport and Traps in the Tradeoff Between Low OFF-State Leakage Current and Improved Dynamic Stability of AlGaN/GaN HFETs

A tradeoff behavior between low Schottky gate leakage current and improved dynamic stability of AlGaN/GaN heterostructure FETs was previously reported, and was attributed to variations in the metal/semiconductor interface properties. Here, we show that a tradeoff behavior is found in transistors and gated van der Pauw test structures that were fabricated on the same wafer, and underwent identical surface treatments. In the gated van der Pauw measurements, a slow transient response and a large variation in the 2-D electron gas concentration compared with equilibrium were detected, following a gate voltage stress in low leakage devices, but not in high leakage ones. Based upon our experimental observations, we argue that electron traps located in the AlGaN barrier layer are responsible for the tradeoff. The activation energies required to fill the empty barrier traps by electrons, obtained from the gated van der Pauw measurements, are 0.60 and 0.65 eV.

What Is Your Favorite Local Food Menu Application of Conjoint Analysis on the Eastern Mediterranean Cuisine of Turkey

Aim of this study is twofold; (1) investigating consumers’ preference for favorite local food menu composed of regionally known soups, appetizers, main courses and desserts, and (2) understanding the criteria on which the consumers show their trade-off attitudes. Data was collected during the 01-31 May 2015 through a survey composed of 18 menu cards and 154 usable questionnaires were gathered as a consequence. Full profile conjoint analyses were applied as statistical technique in order to analyzing data. Major findings from the empirical study point to the fact that participants confer the highest importance to the main dishes while the least importance is placed on the price. The most favored menu cards reveal that those with ‘Adana kebab’ are of priority to the consumers. The most favorite menu card is composed of a mixture of Adana and Gaziantep cuisines. This tradeoff behavior by the consumers illustrates that the more variety presented in the local menu, the higher the prices that could be charged.

Setting Preferences of High and Low Use River Recreationists: How Different are They?

Whitewater boaters often choose a river based on their preferences for attributes important for their trip experience. This study explored whether preferences and tradeoffs of whitewater boaters for social, resource, and managerial attributes of riverscapes differ among a high and a low use river in the United States by employing a stated choice approach. River trip scenarios were displayed using verbal descriptions and computer-generated photographs. Results indicate that use levels were more important for boaters on the low use river, whereas river difficulty and river access fee was of higher importance for the high use river boaters, who are more involved in this whitewater activity. Preferences for waiting times and trip length did not differ between the samples. Findings suggest that whitewater boaters of high and low use rivers have a different tradeoff behavior among river setting attributes, which has implications for river recreation management.

Firm-Level Determinants of the Financing Decisions of Small and Medium Enterprises: Evidence from Argentina

ABSTRACTThis article studies the determinants of the financing decisions of small and medium enterprises (SMEs), which we characterize through three cases: trade-off behavior, pecking order, and extreme aversion to debt. We test our hypotheses using a dataset of firms from Bahía Blanca (Argentina) for two years: 2006 and 2010. We find that firm characteristics related to information asymmetries, such as firm age, size, and legal form; and personal factors, such as owner’s age and education; and perception of emotional bankruptcy costs, are relevant variables in SME financing behavior. The recognition of extreme aversion to debt motivates reconsideration of the underleverage problem of SMEs.

Mean Reverting Financial Leverage and Firm Life Cycle: Theory versus Evidence (Pakistan)

The purpose of the study 3 3 This article is a part of a PhD thesis submitted at School of Accounting, Dongbei University of Finance and Economics, Dalian, P. R. China. is to decide between two competing theories of capital structure (trade-off theory and pecking order theory) along a firms’ life cycle and to find out whether there exists a target capital structure or not. To carry out the purpose, we develop a database of 13,375 firm-year observations of non-financial firms listed on Pakistan Stock Exchange spread over 39 years (1972–2010). A multivariate approach has been followed to classify 13,375 firm-year observations into different life cycle stages, and Fisher type panel unit root test has been applied to check the mean reversion of financial leverage ratios. The results of unit root analysis for growing and mature firms clearly support trade-off financing behavior while for declining firms results do not support trade-off financing behavior.

Behavioral Thermoregulation and Trade-Offs in Juvenile Lobster Homarus americanus.

Water temperature influences the behavior and distribution patterns of both larval and adult American lobster Homarus americanus. However, very little is known about the responses of juvenile lobsters. The juvenile life stage is a critical period; high levels of mortality, combined with specific behavioral responses, can disconnect larval settlement from patterns of abundance of adults. We assessed behavioral thermoregulation in juvenile lobsters, and determined how thermal preferences can be altered by the presence of shelter and food. Juvenile lobsters avoided temperatures higher than 20 °C and lower than 8 °C, and had a mean temperature preference of 16.2 ± 1 °C. This preference was unaffected by prior acclimation, origin (laboratory-raised or wild), or size. When the animals were subjected to a temperature change (5-20 °C), activity rates peaked at 15 °C, and remained stable thereafter. Activity rates did not change when a shelter was added. The addition of food resulted in an increase in activity associated with food handling. When juvenile lobsters were offered a choice between temperature, shelter, and food, they always chose the environment with a shelter, even when it was in a thermally unfavorable temperature. Juveniles also spent more time in a thermally unfavorable environment when food was present; however, acquisition of a shelter was prioritized over food. Although juveniles had a similar thermal preference to adults, they are more vulnerable to predation; the innate shelter-seeking behavior of juveniles overrode their thermal preference. While temperature is an important environmental factor affecting the physiology, distribution, and growth of aquatic ectotherms, our findings suggest that trade-off behaviors occur in order to maintain optimal fitness and survival of the individual.

A revised correlation between molecular weight between crosslinks and equilibrium degree of swelling of hydrogel networks

Event Abstract Back to Event A revised correlation between molecular weight between crosslinks and equilibrium degree of swelling of hydrogel networks Dany J. Munoz-Pinto1 and Mariah S. Hahn2 1 Trinity University, Engineering Science, United States 2 Rensselaer Polytechnic Institute, Biomedical Engineering, United States Introduction: Among hydrogels properties, characterization of their capacity to transport solutes of different sizes is of great relevance for the biomedical community. Their diffusional capacity has been commonly estimated using the average molecular weight between crosslinks (Mc) which is calculated using equilibrium degree of swelling data[1]. However, the current correlation lacks of sensitivity and fails to accurately reflect the diffusional properties of more highly crosslink hydrogel networks[2]. To address this limitation, the present work first evaluated the robustness of the standard swelling correlation using poly(ethylene glycol) diacrylate (PEGDA) as a material model. The strength of the correlation was assessed by contrasting swelling and mechanical behavior as functions of hydrogel crosslink density (ρx).Second, an independent assessment of hydrogel mesh size (ξ) by molecular size exclusion (MSE) was utilized to calculate ρx. The resulting set of data followed more general trends for swelling and modulus. Finally, using the MSE data, an improved correlation between Mc and degree of swelling was generated. Material and Methods: Hydrogel Preparation. Hydrogels were prepared by the photopolymerization of aqueous solutions of 3.4, 6.0, 10.0 and 20.0 kDa PEGDA. For each PEGDA MW, six distinct polymer concentrations ranging from 8 to 30 wt% were characterized. Swelling Measures. The volumetric swelling ratios at the swollen and relaxed states (Q and Q’) were calculated from the hydrogel initial, swollen and dry weights. Mc and ρx for each hydrogel formulation were then determined using swelling data correlations[1]. Mesh Size Evaluation. Mesh size was independently estimated by molecular size exclusion experiments[3],[4]. The measured ξ was then used to back calculate Mc and ρx. Tensile Modulus (E) Evaluation. The modulus of each formulation was determined from the slope of the linear portion of the stress-strain curve using a ring test method and an Instron 3342 mechanical tester[5]. New Swelling Correlation Model. To generate a new model to correlate Mc and swelling data, the value 1/Mc from the MSE data and the effective number of chain per unit volume (Vc) from swelling data were fit to the linear model: 1/Mc=a+bVc'. Where Vc'=f(Q,Q')*Vc. Results and Discussion: As expected, Q and E of PEGDA hydrogels as functions of ρx exhibited a tradeoff behavior for both sets of data (Fig. 1A and 1B).However only the ρx estimates based on MSE-based mesh size measures (Fig. 1B) resulted in a general ρx-Q trend, which was independent of PEGDA MW. Furthermore, the data from MSE model was used to derive an improved correlation between Mc and degree of swelling of hydrogel networks (Fig. 1C). Conclusions: The current data shows that the values of 1/Mc can potentially be calculated from swelling data using a modified version of the current correlation. Although in this work we used PEGDA as a model, this correlation can potentially be extended to other polymer networks.

Is There Evidence for a Mixture of Processes in Speed-Accuracy Trade-Off Behavior?

The speed-accuracy trade-off (SAT) effect refers to the behavioral trade-off between fast yet error-prone respones and accurate but slow responses. Multiple theories on the cognitive mechanisms behind SAT exist. One theory assumes that SAT is a consequence of strategically adjusting the amount of evidence required for overt behaviors, such as perceptual choices. Another theory hypothesizes that SAT is the consequence of the mixture of multiple categorically different cognitive processes. In this paper, these theories are disambiguated by assessing whether the fixed-point property of mixture distributions holds, in both simulations and data. I conclude that, at least for perceptual decision making, there is no evidence for a mixture of different cognitive processes to trade off accuracy of responding for speed.

Mean reverting financial leverage: theory and evidence from Pakistan

Grounding concepts of the two competing theories of capital structure (trade-off theory, pecking order theory) are quite opposite to each other. Trade-off theory claims that there is an optimal (target) capital structure and firms try to achieve that optimal (target) point. Whereas pecking order theory argues that there is no optimal (target) capital structure but the firms follow a specific pattern of financing. Using the two competing theoretic frameworks, this study applies Fisher-type panel unit root test to an unbalanced panel data of 13 115 firm-year observations of nonfinancial firms listed on Karachi Stock Exchange Pakistan spread over 38 years (1973–2010). Overall panel test results, for short-term, long-term, as well as total leverage support trade-off financing behaviour while individual firm results do not. Individual firm results show that only 16% of the firms have short-term target, 25% of the firms have long-term target and 12% of the firms have total target leverage ratio. Further, industry results explain that most of the industries do have target leverage ratios and classification of data into profitable and lossmaking firm-year observations explains that profitable firms clearly follow trade-off financing behaviour while the results for lossmaking firms do not support trade-off financing behaviour. Our study indicates that it is important for the government to ensure policies to develop well-balanced financial markets and to improve accountability systems.

Allocation of cognitive resources in comparative visual search – Individual and task dependent effects

Behaviors recruit multiple, mutually substitutable types of cognitive resources (e.g., data acquisition and memorization in comparative visual search), and the allocation of resources is performed in a cost-optimizing way. If costs associated with each type of resource are manipulated, e.g., by varying the complexity of the items studied or the visual separation of the arrays to be compared, according adjustments of resource allocation (“trade-offs”) have been demonstrated. Using between-subject designs, previous studies showed overall trade-off behavior but neglected inter-individual variability of trade-off behavior. Here, we present a simplified paradigm for comparative visual search in which gaze-measurements are replaced by switching of a visual mask covering one stimulus array at a time. This paradigm allows for a full within-subject design. While overall trade-off curves could be reproduced, we found that each subject used a specific trade-off strategy which differ substantially between subjects. Still, task-dependent adjustment of resource allocation can be demonstrated but accounts only for a minor part of the overall trade-off range. In addition, we show that the individual trade-offs were adjusted in an unconscious and rather intuitive way, enabling a robust manifestation of the selected strategy space.

Multiobjective optimization of process parameters for plastic injection molding via soft computing and grey correlation analysis

In the plastic injection molding (PIM), the optimization of the process parameters is a complex task. The objective of this study is to propose an intelligent approach for efficiently optimizing PIM parameters when multiple objectives are involved, where different objectives, such as minimizing part weight, flash, or volumetric shrinkage, present trade-off behaviors. Multiple objective functions reflecting the product quality are constructed for the optimization model of PIM parameters. The proposed approach integrates Taguchi’s parameter design method, back-propagation neural network (BPNN), grey correlation analysis (GCA), particle swarm optimization (PSO) and multiobjective particle swarm optimization (MOPSO) to locate the Pareto optimal solution for multiobjective optimization problem. PSO and GCA are applied to optimize the network structure of BPNN to establish multiobjective mathematical model (PSO-GCANN) that finely maps the relationship between the input process parameters and output multiresponse. MOPSO is used to fine-tune the Pareto optimal solutions while the approximate PSO-GCANN is utilized to efficiently compute the fitness of every individual during the evolution of MOPSO. The illustrative application and comparison of results show that the proposed methodology outperforms the existing methods and can help mold designers to efficiently and effectively identify optimal process parameters.

Multi-objective optimization of microfluidic fuel cell

Microfluidic fuel cells operate in the laminar flow regime, thus their fuel utilization is low. A trade-off exists between fuel utilization and output power density. To achieve high output power density and fuel utilization simultaneously, several parameters should be optimized. We have employed a multi-objective optimization method to optimize a simple Y-shaped microfluidic fuel cell with rectangular cross section channel. An electrochemical model for microfluidic fuel cell in MATLAB environment is developed and validated. By coupling this model with multi-objective optimization algorithm the multi-objective optimization problem is defined. Genetic algorithm is used to solve this multi-objective optimization problem. The Pareto set, represents a quantitative description of the trade-off between power density and fuel utilization. The results show that to make the most of the power density-fuel utilization trade-off behavior, fuel cell should be operated at current density no more than 0.9 mW/cm2. Almost for all solutions in Pareto set, the values of channel width and fuel concentration are 0.5 mm and 12 mol/m3, respectively.

A design procedure for improving the effectiveness of fractal layouts formation

AbstractRecently, new types of layouts have been proposed in the literature in order to handle a large number of products. Among these are the fractal layout, aiming at minimization of routing distances. There are already researchers focusing on the design; however, we have noticed that the current approach usually executes several times the allocations of fractal cells on the shop floor up to find the best allocations, which may present a significant disadvantage when applied to a large number of fractal cells owing to combinatorial features. This paper aims to propose a criterion, based on similarity among fractal cells, developed and implemented in a Tabu search heuristics, in order to allocate it on the shop floor in a feasible computational time. Once our proposed procedure is modeled, operations of each workpiece are separated in n subsets and submitted to simulation. The results (traveling distance and makespan) are compared to distributed layout and to functional layout. The results show, in general, a trade-off behavior, that is, when the total routing distance decreases, the makespan increases. Based on our proposed method, depending on the value of segregated fractal cell similarity, it is possible to reduce both performance parameters. Finally, we conclude the proposed procedure shows to be quite promising because allocations of fractal cells demand reduced central processing unit time.

Design and Optimization of Multiple Microchannel Heat Transfer Systems

In this paper, two different configurations of multiple microchannel heat sinks, with fluid flow, are investigated for heat removal: straight and U-shaped channel designs. Numerical models are utilized to study the multiphysics behavior in the microchannels and these are validated by comparisons with experimental results. The main focus of this work is on the design and optimization of these systems and to outline the methodology that may be used for other similar thermal systems. Three responses, including thermal resistance, pressure drop, and maximum temperature, are parametrically modeled with respect to various design variables and operating conditions such as dimensions of the channels, total number of channels, and flow rate. Multi-objective optimization problems, which minimize the thermal resistance and the pressure drop simultaneously, are formulated and studied. Physical constraints in terms of channel height, maximum temperature, and pressure are further investigated. The Pareto frontiers are studied and the trade-off behavior between the thermal resistance and the pressure drop are discussed. Characteristic results are presented and discussed.

Behavioural foundations of two-fluid model for urban traffic

Traditionally traffic flow models have been based on analogous physical phenomena. Though these models have been successful in representing traffic flow, there is a need to provide a systematic behavioural explanation for their existence. One such model is the two-fluid model which is analogous to the principles of Bose–Einstein condensation of particles at low temperatures. The model has been extensively used to characterize the quality of traffic on urban networks and arterial streets. The two parameters of the model essentially represent ‘free flow’ travel time and level of interaction among vehicles. Though the studies have found the parameters of the two-fluid model to be significantly correlated with driver behaviour (aggressive/conservative) and crash rates, no systematic behavioural explanation has been found. This paper proposes a behavioural framework based on individual trade-off behaviour to explain the two-fluid model phenomenon. The two-fluid model is derived based on a driver’s attempt to maximize his quality of travel, by travelling fast while maintaining safety. Contrary to earlier assumptions the proposed framework shows the two parameters to be correlated. The theoretical framework was tested using two-fluid model data from various cities. The data was also used to estimate the effects of geometric factors on the perception of likelihood of a crash and the severity of the crash that affect the two-fluid model. Increase in the fraction of one-way streets was found to reduce the driver’s perception of likelihood to crash. While reduction in the fraction of one way streets and increase in average number of lanes per street, signal density and fraction of actuated signals increased the perceived level of severity of a crash.

Pareto optimisation of railway bogie suspension damping to enhance safety and comfort

This paper presents the optimisation of damping characteristics in bogie suspensions using a multi-objective optimisation methodology. The damping is investigated and optimised in terms of the resulting performances of a railway vehicle with respect to safety, comfort and wear considerations. A complete multi-body system model describing the railway vehicle dynamics is implemented in commercial software Gensys and used in the optimisation. In complementary optimisation analyses, a reduced and linearised model describing the bogie system dynamics is also utilised. Pareto fronts with respect to safety, comfort and wear objectives are obtained, showing the trade-off behaviour between the objectives. Such trade-off curves are of importance, especially in the design of damping functional components. The results demonstrate that the developed methodology can successfully be used for multi-objective investigations of a railway vehicle within models of different levels of complexity. By introducing optimised passive damping elements in the bogie suspensions, both safety and comfort are improved. In particular, it is noted that the use of optimised passive damping elements can allow for higher train speeds. Finally, adaptive strategies for switching damping parameters with respect to different ride conditions are outlined and discussed.

Gas transport properties of Pebax®/room temperature ionic liquid gel membranes

This work evaluates the possibility to tailor the gas separation properties of elastomeric block co-polyamide membranes by means of room temperature ionic liquid (RTIL), based on the 1-n-alkyl-3-methylimidazolium cation. Polymeric gel membranes were prepared by adding from 20 to 80wt.% of 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [BMIM][CF3SO3] to Pebax®1657 and Pebax®2533.The effect of the ionic liquid on the microstructure, properties and performance of these membranes was discussed.DSC analysis showed a gradual decrease of the melting point of the polyamide (PA) blocks in the gel with a decrease in the corresponding melting enthalpy and a complete disappearance of the crystallinity of the polyether (PE) phase with increasing IL content in the case of Pebax®1657. In Pebax®2533 there is virtually no shift in the peak positions and both crystal phases remain present in the gel, indicating effective phase separation between the crystalline fraction of the polymer and the IL, in contrast with the high compatibility and the good mixing of the polymer and the IL observed in Pebax®1657.In the presence of the ionic liquid, the elastic modulus, break strength and maximum elongation all decrease monotonously for Pebax®2533. For the stiffer Pebax®1657 the break strength and maximum elongation show a maximum at low ionic liquid content and then rapidly decrease at higher IL concentration due to compromise between the plasticizing effect of the IL, enhancing its ductability, and the progressive weakening of the gel due to a reduction of the crystal fraction responsible for the mechanical strength.Gas permeation measurements show that the permeability and selectivity of Pebax®2533 are not notably affected by the addition of IL, whereas Pebax®1657 shows a significant increase in the gas permeability. At the same time the permselectivity of the latter for most gas pairs shows a slight decrease, in accordance with the typical Robeson trade-off behaviour. The combination of permeability and selectivity remains nevertheless interesting for applications involving for instance CO2 removal from exhaust gases.

Valuing Aviation Noise with the Contingent Valuation Method

Aviation noise from Suvarnabhumi Airport, Bangkok, Thailand, has had a severe impact on the quality of life of people who live in the surrounding areas since the airport began operation in 2006. The airport authority offered to buy homes in the most severely affected areas or to provide funds to soundproof them, but the compensation program was aimed mainly at homeowners, not renters of apartments or dormitories. In previous studies in Thailand, the focus was on examining the noise depreciation of home values by hedonic price modeling. In this paper, the scope of previous research is broadened to include the noise impact on renters by using the contingent valuation method to examine their willingness to accept compensation (WTA) when the noise level increases. Estimation of WTA was based on a choice experiment in which subjects were asked to evaluate alternatives in hypothetical scenarios and to select their preferred alternative. Scenarios with various levels of flight frequency and amounts of compensation were systematically developed to study trade-off behavior between these attributes. Coefficient estimates of the multinomial logit model imply that the WTA for an increase of one flight movement ranges from 18.87 to 68.62 baht (US$0.63 to US$2.29) per month. The results of this study can be useful in informing the airport authority's noise compensation policy, which needs to be revised in the near future in light of plans for the airport's expansion.

Multi-objective optimization of MIMO plastic injection molding process conditions based on particle swarm optimization

Determining optimal process parameter settings critically influences productivity, quality, and cost of production in the plastic injection molding industry. Selecting the proper process conditions for the injection molding process is treated as a multi-objective optimization problem, where different objectives, such as minimizing product weight, volumetric shrinkage, or flash present trade-off behaviors. As such, various optima may exist in the objective space. This paper presents the development of an experiment-based optimization system for the process parameter optimization of multiple-input multiple-output plastic injection molding process. The development integrates Taguchi’s parameter design method, neural networks based on PSO (PSONN model), multi-objective particle swarm optimization algorithm, engineering optimization concepts, and automatically search for the Pareto-optimal solutions for different objectives. According to the illustrative applications, the research results indicate that the proposed approach can effectively help engineers identify optimal process conditions and achieve competitive advantages of product quality and costs.