bluuebunny/crossref_metadata_2025 huggingface dataset:
Experience‐based modulation of behavioural responses to plant volatiles and other sensory cues in insect herbivores
Authors: ANDERSON P. , ANTON S.
Published: April 2014

Plant volatiles are important cues for many herbivorous insects when choosing a suitable host plant and finding a mating partner. An appropriate behavioural response to sensory cues from plants and other insects is crucial for survival and fitness. As the natural environment can show both large spatial and temporal variability, herbivores may need to show behavioural plasticity to the available cues. By using earlier experiences, insects can adapt to local variation of resources. Experience is well known to affect sensory‐guided behaviour in parasitoids and social insects, but there is also increasing evidence that it influences host plant choice and the probability of finding a mating partner in herbivorous insects. In this review, we will focus upon behavioural changes in holometabolous insect herbivores during host plant choice and localization of mating partners, modulated by experience to sensory cues. The experience can be acquired during both the larval and the adult stage and can influence later responses to plant volatiles and other sensory cues not only within the developmental stage but also after metamorphosis. Furthermore, we will address the neurophysiological mechanisms underlying the experience‐dependent behavioural adaptations and discuss ecological and evolutionary aspects of insect behavioural plasticity based upon experience.
Is stomatal conductance optimized over both time and space in plant crowns? A field test in grapevine (Vitis vinifera)
Authors: BUCKLEY THOMAS N. , MARTORELL SEBASTIA , DIAZ‐ESPEJO ANTONIO , TOMÀS MAGDALENA , MEDRANO HIPÓLITO
Published: April 2014

Crown carbon gain is maximized for a given total water loss if stomatal conductance (gs) varies such that the marginal carbon product of water (∂A/∂E) remains invariant both over time and among leaves in a plant crown, provided the curvature of assimilation rate (A) versus transpiration rate (E) is negative. We tested this prediction across distinct crown positions in situ for the first time by parameterizing a biophysical model across 14 positions in four grapevine crowns (Vitis vinifera), computing optimal patterns of gs and E over a day and comparing these to the observed patterns. Observed water use was higher than optimal for leaves in the crown interior, but lower than optimal in most other positions. Crown carbon gain was 18% lower under measured gs than under optimal gs. Positive curvature occurred in 39.6% of cases due to low boundary layer conductance (gbw), and optimal gs was zero in 11% of cases because ∂A/∂E was below the target value at all gs. Some conclusions changed if we assumed infinite gbw, but optimal and measured E still diverged systematically in time and space. We conclude that the theory's spatial dimension and assumption of positive curvature require further experimental testing.
Dissociable effects of psychopathic traits on cortical and subcortical visual pathways during facial emotion processing: An ERP study on the N170
Authors: Almeida Pedro R. , Ferreira‐Santos Fernando , Vieira Joana B. , Moreira Pedro S. , Barbosa Fernando , Marques‐Teixeira João
Published: April 2014

This study examined the relation between psychopathic traits and the brain response to facial emotion by analyzing the N170 component of the ERP. Fifty‐four healthy participants were assessed for psychopathic traits and exposed to images of emotional and neutral faces with varying spatial frequency content. The N170 was modulated by the emotional expressions, irrespective of psychopathic traits. Fearless dominance was associated with a reduced N170, driven by the low spatial frequency components of the stimuli, and dependent on the tectopulvinar visual pathway. Conversely, coldheartedness was related to overall enhanced N170, suggesting mediation by geniculostriate processing. Results suggest that different dimensions of psychopathy are related to distinct facial emotion processing mechanisms and support the existence of both amygdala deficits and compensatory engagement of cortical structures for emotional processing in psychopathy.
Survival analysis of time‐to‐event data in respiratory health research studies
Authors: Kasza Jessica , Wraith Darren , Lamb Karen , Wolfe Rory
Published: April 2014

This article provides a review of techniques for the analysis of survival data arising from respiratory health studies. Popular techniques such as the Kaplan–Meier survival plot and the Cox proportional hazards model are presented and illustrated using data from a lung cancer study. Advanced issues are also discussed, including parametric proportional hazards models, accelerated failure time models, time‐varying explanatory variables, simultaneous analysis of multiple types of outcome events and the restricted mean survival time, a novel measure of the effect of treatment.
Mycobacterium avium complex infection in non‐cystic fibrosis bronchiectasis
Authors: Zoumot Zaid , Boutou Afroditi K. , Gill Simon S. , van Zeller Mafalda , Hansell David M. , Wells Athol U. , Wilson Robert , Loebinger Michael R.
Published: April 2014

Background and objective

Reliable markers of disease progression or stability to assist in management decisions are lacking in patients with non‐cystic fibrosis bronchiectasis and Mycobacterium avium complex (MAC) infection.

Methods

Data from 52 adults with non‐cystic fibrosis bronchiectasis and coexisting MAC infection managed at our institution over a 5‐year period were retrospectively analysed. High‐resolution computed tomography (HRCT) scans were scored using a scoring system that focused on findings associated with MAC infection.

Results

Chronic pulmonary aspergillosis was independently associated with mortality (hazard ratio (HR) = 8.916, 95% confidence interval (CI) = 1.324–60.027), as were nodules with cavitation (HR = 5.911, 95% CI = 1.095–25.911) and emphysema (HR = 1.027, 95% CI = 1.002–1.053) on HRCT. Anti‐MAC chemotherapy was more likely to lead to MAC culture conversion (67% vs 27%, P = 0.005) but did not improve survival as compared with patients managed with observation. Longitudinally, patients who had improvements in HRCT scores were younger (60.2 ± 9.19 years vs 69.83 ± 12.43 years, P = 0.043), while the presence of cavitation within nodules predicted a deterioration in HRCT scores (0.5 (0–3) vs 0 (0–1), P = 0.033). No significant longitudinal differences were found in lung function in the cohort as a whole or within different groups.

Conclusions

Chronic pulmonary aspergillosis in patients with bronchiectasis and coexisting MAC infection is a strong predictor of mortality. Cavitation within nodules and emphysema on HRCT at presentation were independently associated with mortality.
Measuring the Impact of Trade Protection on Industrial Production Size
Authors: Tian Wei , Yu Miaojie
Published: April 2014

Trade theory has no clear prediction on how import protection affects an importing sector's relative size. In this paper, we estimate the impact of US trade protection on industrial production relative size based on a translog GDP functional system. Using an industrial panel data set and controlling for factor endowments and technology improvement, we find empirical evidence that trade protection does not help much increase a sector's relative size. Such findings are also robust to both the inclusion of the role of political economy and the coverage of various non‐tariff measures as proxies of industrial protection.
Religious Attitudes and Home Bias: Theory and New Evidence from Primary Data
Authors: Leroch Martin A. , Reggiani Carlo , Rossini Gianpaolo , Zucchelli Eugenio
Published: April 2014

This paper examines the relationship between religion and home bias. A theoretical framework is proposed suggesting that countries may show a certain degree of religion‐enhanced international altruism associated with a lower home bias. These predictions are investigated empirically using original individual‐level data from a survey on religious attitudes and home bias that was designed and collected in 15 countries. Contrary to previous evidence, the empirical investigation suggests that religious denominations may not play an important role in determining home bias. The findings partly corroborate the hypothesis that an open and tolerant attitude towards religion may enhance trust and altruism and, hence, may have a pro‐trade effect by lowering home bias. It is concluded that models investigating the relationship between religion and home bias should incorporate different aspects of religion beyond affiliations and should consider different dimensions of home bias.
Tat's All Folks: An Analysis of Tattoo Literature
Authors: Lane David C.
Published: April 2014

The purpose of this manuscript is to review the existing literature on the subject of tattooing. By focusing on the unit of analysis, this paper demonstrates that little is actually known about the process of tattooing. This review highlights how research on the subject is concentrated on understanding tattoo wearers. Existing literature on tattooing can be summarized into one of four general themes or sets of findings: tattooed individuals, group behavior, art or cultural production, and commoditization of culture. While viewed as a trivial subject, research indicates that tattooing is highly complex and social behavior. I propose that research shift from tattoos as the outcome cultural production to the social processes and conditions under which they are produced. While we know a lot about tattoo wearers, research on the process of tattooing can inform larger sociological debates, including discussions of labor, commodification, art, authenticity, and marginality.
The Network Structure of Crime
Authors: Papachristos Andrew V.
Published: April 2014

From theoretical physics to field‐driven anthropology, researchers are increasingly exploring how the connections among individuals, amoebas, brain cells, organizations, and institutions affect what we feel, think, and do. However, the application of social network analysis to the study of crime, deviance, and violence has arrived a bit late to this network turn in the social and behavioral science. I argue that this network turn in the social sciences be an important turning point in the study of crime and deviance, but only if taken as an opportunity to evaluate our core theoretical principles and consider new ways to understand and measure them. The goal of this essay is to take stock of the state of the field, while also providing a moment of pause to consider some fruitful ways of advancing this line of inquiry.
Proving Themselves: The Status of LGBQ Police Officers
Authors: Miller Susan L. , Lilley Terry G.
Published: April 2014

The policing occupation, a bastion of hegemonic masculinity, is well known for its historical resistance to “difference,” whether among its own members or in society at large. Nowhere does this clash manifest as strongly as when LGBQ police officers join the force. LGBQ individuals have made great strides in breaking down some beliefs of the traditional and rigid police occupational culture. Still, more progress remains to be made toward dismantling the barriers of heterosexism and sexism that often permeate policing. This article explores the history of these barriers, the progress made, and the structural and individual level obstacles that remain. Policy recommendations and suggestions for future research are also made.
Establishment of reference panel for human platelet antigen genotyping
Authors: Li R. S. , Qiao Z. L. , Ling B. , Lu P.
Published: April 2014

Background and Objectives

Human platelet antigens (HPAs) are platelet‐specific alloantigens associated with polymorphisms of platelet surface glycoproteins (GPs), and they can induce alloantibodies when individuals lacking a particular polymorphism are exposed to them via pregnancy or transfusion. Immune responses to HPAs are involved in the pathogenesis of several clinical syndromes. HPA genotyping is therefore important for clinical diagnosis and laboratory research. This study aims to establish a reference panel for HPA genotyping.

Materials and Methods

Genomic DNA extracted from human blood was used as the template for amplifying HPA (1a–5a and 15a) gene fragments using specific primers. The amplified products were cloned into pGM‐T vectors, which were transformed into competent TOP10 cells. After clone screening and amplification, the plasmids were extracted and sequenced. Next, the gene fragments HPA‐1b–5b and 15b were obtained by site‐directed mutagenesis using the corresponding HPA‐1a–5a and 15a plasmids as template DNA.

Results

We successfully constructed reference plasmids for HPA genotyping with HPA‐1a–5a, 15a, HPA‐1b–5b and 15b. The DNA sequences were consistent with those published in GenBank.

Conclusion

Obtaining reference DNA for low‐frequency HPAs is very difficult, and the successful construction of reference plasmids for the six HPA systems may solve this problem. Establishment of this panel has laid the foundation for future research on HPA genotyping.
Design and Computational Validation of In-Line Bare Tube Economizer for a 210 MW Pulverized Coal Fired Boiler
Authors: Dhamangaonkar P. R. , Deshmukh Abhishek , Pansare Santosh , Nandgaonkar M. R.
Published: April 2014

One of the pulverized coal fired thermal power plants in India intended to find the root cause of frequent boiler tube failures in three 210 MW units. Operation & Maintenance history and feedback from plant O&M team revealed that economizer tube failure was a frequent cause of forced outage. The plant under study used CFS (continuous fin surface) economizer with staggered tube arrangement in the 210 MW units. CFS staggered tube economizers originally appealed to many plant designers because the tortuous path created for the flue gas, enhanced heat absorption and the fins could capture heat and transfer it to the tubing. This made the CFS economizer less costly and easy for installation in a relatively small space.

There is increasing use of lower quality high ash coals over the past few decades. Due to this fact an advantage of the CFS economizer design became a disadvantage. The narrow spacing in the tubes proved more susceptible to plugging and fly ash erosion. Literature study and the root cause analysis suggested that CFS staggered arrangement of economizer could be one of the prominent reason of failure of economizer tube bundle due to fly ash erosion. Flue gas flow simulation also highlighted that there is increase in velocity of flue gases across the economizer. A bare tube in-line configuration in place of existing CFS economizer was an alternative. To recommend an alternate economizer as solution, the merits of an in-line bare tube economizer were studied. Bare tubes arranged in-line are most conservative in hostile environments with high ash content, are least likely to plug, and have the lowest gas-side resistance per unit of heat transfer.

A bare tube in-line economizer that can replace the existing finned tube economizer in the available space while meeting the existing design & performance parameters is recommended. An attempt was made to model & analyze the new economizer using computational fluid dynamics (CFD) tools in order to get firsthand experience and validate the results obtained using manual calculations. With limited computational resources and not so fine meshing, the performed CFD model analysis showed the expected trend but did not completely match the results.
Role of Internal Radiation With or Without Melt Inclusions During Czochralski Sapphire Crystal Growth
Authors: Fang H. S. , Zhang Q. J. , Zheng L. L. , Zhang M. J. , Tian J.
Published: April 2014

Sapphire is the most popular substrate material for GaN thin-film crystal growth during the Light-emitting diode (LED) fabrication. The performance of GaN films is directly influenced by the quality of the substrates. The control of the growth front, i.e., solid /liquid interface, is critical to improve the quality of the sapphire. As a semi-transparent material, sapphire has an intermediate optical thickness, which requires considering of internal radiation for an accurate prediction of temperature field and interface shape. In the paper, a coupled model has been applied on the modeling of transport phenomena during the Czochralski (Cz) sapphire growth. Especially, the role of the internal radiation with or without melt inclusions has been examined carefully by Discrete Ordinates (DO) method. The interface convexity is influenced by the parameters of the models as well as by the melt inclusions. By setting the different optical properties at the inclusion regions, as observed in the experiments, the entrapment of gas or solid inclusions inside the crystal and its effect on the interface shape are examined.
Locally Precise Response Surface Models for the Generalization of Controlled Dynamic Systems and Associated Performance Measures
Authors: McDonald Dale B.
Published: April 2014

This treatment demonstrates the utility of response surface models (RSMs) as predictive, companion tools which aid in the development of harvesting (control) strategies applicable to predator-prey dynamic systems. To this end a control algorithm is derived that considers the regulation of a predator-prey natural resource while considering revenue for commercial ventures and regulatory agencies. Numerical simulations provide the mechanism to quantify performance measures associated with control algorithms, yet complicated problems require that all “tools” available be considered. Complex problems may be more tractable when simulation results are combined with alternate, continuous models exhibiting predictive capacities. For this reason, RSMs are appealing; analytic evaluation of the state, the gradient, and the Hessian matrix is possible. From these models we may glean valuable information linked to the gathered data revealing information about the “true nature” of the ecological system. Therefore, we propose to create RSMs based on scattered data obtained from the ordinary differential equation (ODE) dynamic system model. These response surface models are constructed using radial basis functions (RBFs); RSMs so created have the desirable property of matching the objective function value exactly at each sampled data point. Furthermore, they have the ability to interpolate to any desired point throughout the parameter space. This is powerful as the “objective function” may be any function of critical importance to the analyst which in this treatment is the predator biomass time rate of change (ODE) itself. This has the immediate implication of providing a single ODE model, with a “locally” or even perhaps a “globally” precise nature. Since such models are constructed from scattered data, which is consistent with what would be collected from field measurements, a further connection of theory to practice is realized. It will be shown that these RSMs provide greater insight into ecological systems, with special emphasis on parameter estimation.
Design of a Discharge Header and a Working Platform for a Research Reactor With a CFD Model
Authors: Seo Kyoungwoo , Yoon Hyungi , Chi Dae-young , Kim Seonghoon , Yoon Juhyeon
Published: April 2014

Most research reactors are designed as an open-pool type and the reactor is located on the bottom of the open-pool. The reactor in the pool is connected to the primary cooling system, which is designed for adequate cooling of the heat generated from the reactor core. One of the characteristics of an open-pool type research reactor is that the primary coolant after passing through the reactor core and the primary cooling system (PCS) is returned to the reactor pool. Because the primary coolant contains many kinds of radionuclides, the research reactor should be designed to protect the radionuclides from being released outside the pool by a stratified stable water layer, which is formed between a hot water layer and cold water near the reactor and prevents the natural circulation of water in the pool. In this study, additional components such as a discharge header and a working platform inside the pool were developed to help diminish the radiation level to the pool top. To discharge coolant stably inside the reactor pool, a discharge header was installed at the end of the pool inlet pipe. Many holes were made in the discharge header to discharge the coolant slowly and minimize the disturbance of the hot water layer by the flow inside the pool. The working platform was also equipped inside the reactor pool to remove the convective flow near the pool top.

The commercially available CFD code, ANSYS CFD-FLEUNT, was used to specifically design the discharge header and working platform for satisfying the requirement of the pool top radiation level. The computations were conducted to analyze the flow and temperature characteristics inside the pool for several geometries using an SST k-ω turbulent model and cell modeling, which were conducted to isolate the root cause of these differences and the given inlet conditions. The discharge header and working platform were designed using the CFD results.
Behavior Prediction Model in Gas Fueled Spark Ignition Internal Combustion Engines Turbocharged for Genset Application
Authors: Duarte Forero Jorge , Amador Diaz German , Blanco Castillo Fabio , Corredor Martinez Lesme , Vasquez Padilla Ricardo
Published: April 2014

In this paper, a mathematical model is performed in order to analyze the effect of the methane number (MN) on knock tendency when spark ignition internal combustion engine operate with gaseous fuels produced from different thermochemical processes. The model was validated with experimental data reported in literature and the results were satisfactory. A general correlation for estimating the autoignition time of gaseous fuels in function of cylinder temperature, and pressure, equivalence ratio and methane number of the fuel was carried out. Livengood and Wu correlation is used to predict autoignition in function of the crank angle. This criterium is a way to predict the autoignition tendency of a fuel/air mixture under engine conditions and consider the ignition delay. A chemical equilibrium model which considers 98 chemical species was used in this research in order to simulate the combustion of the gaseous fuels at differents engine operating conditions. The effect of spark advance, equivalence ratio, methane number (MN), charge (inlet pressure) and inlet temperature (manifold temperature) on engine knocking is evaluated. This work, explore the feasibility of using syngas with low methane number as fuel for commercial internal combustion engines.
A General Method for Kinematic Analysis of Epicyclic Bevel Gear Trains Applied to Robotic Wrist Mechanisms
Authors: Talpasanu Ilie
Published: April 2014

This paper presents a novel and simple technique for the kinematic analysis of bevel gear trains (BGT). The approach is based on edge-oriented graphs for efficient computation of BGT’s relative and absolute velocities of links using incidence matrices. The kinematic equations are generated in matrix form using a cycle basis from a cycle matroid. The set of independent equations is automatically obtained from matrix orthogonalities and not by taking derivatives. Equation coefficients are expressed as function of speed ratios and have minimal variables. Then the relationships between the output and input angular velocities can be determined. In addition, a simple procedure is demonstrated to check for mechanism singularities. The method presented here has general applicability and can be employed for spatial geared mechanisms with any number of gears and degrees of freedom as illustrated by numerical examples of robotic wrist mechanisms.
Optimization of Air Plane Wing Rib Using Finite Element Analysis
Authors: Goravi Vijaya Dev Naveen Prakash , Koduru Satish Anoop Kumar , Veerapur Doddabasappa
Published: April 2014

Ribs are the stiffening members in the wing of air plane. Ribs usually have a thin flat plate shape accommodating cutouts, stiffeners and attachments. Most of the time there is a failure of rib due to critical buckling load even though the component is stressed well below the ultimate stress. Hence the rib is designed to carry maximum buckling load. The objective was to increase the critical buckling strength and reduce the weight of the rib. Linear static and buckling analysis were performed on the idealized configuration using FEM packages. Simply supported rectangular plate with different number of inline holes subjected to compression load was evaluated. The material considered was aluminum alloy. Various parametric studies were carried out to arrive at the optimum rib thickness and cross section. Once the optimum thickness of the plate was found out, reduction in the weight of the plate was done by providing various in line circular holes. From the study it was found that inserting circular hole in the plate enhances the buckling strength of the plate. The buckling strength of the plate was increased as the number of holes increased.
Novel, Inexpensive Robot for Teaching Controls Engineering
Authors: Wright Andrew B. , Wright Ann M.
Published: April 2014

A novel Control and Sensor System (CASSY) has been developed to teach controls engineering to electrical and mechanical students. The inexpensive platform, which can be built for under $1500, has a first order velocity loop and a first order yaw rate loop with friction. A detailed model of the robot allows students to perform system identification and compare with the model. Students can implement PID, digital filter, and state space controllers on the robot, vary constants, measure performance, identify stability, and perform step and sine based system identification on the open and closed loop system. Wireless telemetry between the robot and a host computer allow all the control signals to be saved for later analysis. Fabrication guides and training videos are located on robotics.ualr.edu, and the robot has been fabricated by students at UALR and Hendrix College, demonstrating the ease with which the platform can be integrated into a curriculum. The CASSY platform has been used in both undergraduate and graduate control courses at the University of Arkansas at Little Rock. The practical robot experiments have improved learning outcomes of the largely theoretical material.
Dissipation Can Act as a Mechanobiological Signal in Cartilage Differentiation
Authors: Abdel-Sayed Philippe , Vogel Arne , Pioletti Dominique P.
Published: April 2014

Knee cartilage is a soft tissue having viscoelastic properties. Under cyclic loadings, viscoelastic materials dissipate mechanical loadings through heat generation. In knee cartilage, this heat might not be convected because of the tissue avascularity, resulting thus to a local temperature increase. As cells are sensitive to temperature, these thermo-mechanical phenomena of energy dissipation could influence their metabolism. The goal of this study is to evaluate the effect of thermogenesis on chondrogenic differentiation. First, we focused our work in quantifying the heat generated in cartilage as a result to deformation. On a cellular level, the effect of thermal alterations on cell metabolism was assessed looking at the gene expression of transcription factors involved in chondrogenesis. Hence, human chondro-progenitor cells were cultured at 33°C and 37°C for 48 h and 96 h. An up-regulation in mRNA expression levels of Sox9 and its co-activator PGC-1α has been observed. These results point to a thermal contribution to chondrogenic gene expression.
The Role of Jet Fans in Rail Tunnel Safety
Authors: Colino Mark P. , Rosenstein Elena B.
Published: April 2014

Given the high volume of people using today’s public transportation systems, passenger safety has taken on even greater importance in engineering design. This trend has also driven more technical innovation to achieve the same levels of safe ridership using less energy and with reduced cost Jet fens are ideal mechanical systems for emergency ventilation of unidirectional road tunnels; the arched roadway tunnels provide ample space for installation, and this equipment can be operated to transport smoke in the direction of traffic flow — thus enabling stranded motorists to evacuate under clear air in the opposite direction. The application of jet fan systems to multi-directional rail tunnels is not as straightforward, but it can produce significant savings in terms of both energy usage and capital cost, without diminishing passenger safety. The purpose of this paper is to demonstrate how jet fan systems can be applied to rail tunnel networks as mitigating factors against traditionally large, expensive and high energy-consumption fen facilities. This paper covers the key aspects of jet fan implementation — including spatial allowance, operational modes, high-temperature exposure and economic impacts — through presentation of a sample rail tunnel network and analysis of hypothetical emergency ventilation scenarios.
Energy Absorption Mechanisms in Hard Epoxy Resin Matrix Composite Laminates Subjected to Dynamic Loading Events
Authors: Segala David B. , Cavallaro Paul V.
Published: April 2014

Three energy absorption mechanisms of severe dynamic loading events are numerically investigated using a finite element model of a cross-ply unidirectional (UD) composite laminate. In this study, the inelastic energy absorption mechanisms associated with damage at the interfacial and constituent levels were numerically characterized through three admissible failure modes: fiber breakage, matrix shearing, and fiber/matrix debonding (delamination) (i.e., cohesive failure). The UD composite was constructed of ultrahigh molecular weight polyethylene (UHMWPE) fibers separately reinforced with a rigid (epoxy) matrix material. The energy absorption capacities of these damage mechanisms were contrasted for three different dynamic loading cases including blast, shock, and ballistic impact at three different energy levels. Energy loss due to cohesive failure was observed in all three loading cases and energy levels. Furthermore, energy loss due to matrix failure was observed at all energy levels for the blast case, but only for the highest energy level in the shock and ballistics. There was energy loss due to fiber failure in the blast and in the highest energy ballistics impact case. However, there wasn’t any fiber damage in the shock case.
Performance Enhancement of Enhanced Herringbone Wavy-Fin Round Tube Inclined Heat Exchangers With and Without Hydrophilic Coating Using Evaporative Spray and Deluge Cooling
Authors: Popli Sahil , Hwang Yunho , Radermacher Reinhard
Published: April 2014

An experimental study has been conducted to evaluate the performance of two herringbone wavy-fin round tube compact heat exchangers working as coolers, with frontal areas of approximately 0.24 m2 each in both dry and wet conditions. Heat exchanger capacity and air-side pressure drop were measured with the heat exchanger angle set at 20° from vertical. Deluge water cooling was achieved by incorporating a water distributor on top of the heat exchanger from which wetting water overflows as thin film over the top leading edge of the heat exchanger fins. A hollow cone nozzle was used for spray cooling. Water was used as a refrigerant, and enters the heat exchanger tubes at 43°C temperature. Ambient air, deluge and spray cooling water were maintained at 28°C temperature, and frontal air velocity was varied from 1.5 m/s to 3.0 m/s. Capacity was significantly enhanced for all heat exchangers using both deluge and spray cooling. However, the air-side pressure drop penalty ratio was much higher for deluge cooling. Furthermore, heat exchanger with hydrophilic coated fins achieved higher capacity enhancement ratios. This study contributes 8 dry cases and 48 wet cases experimental data points of wavy-fin heat exchanger performance. Future studies would aim at obtaining higher capacity enhancement ratios for spray cooling while maintaining air-side pressure drop penalty ratio of 1.0.
Finite Element Approximation of Fluid Structure Interaction (FSI) Optimization in Arbitrary Lagrangian-Eulerian Coordinates
Authors: Ebna Hai Bhuiyan Shameem Mahmood , Bause Markus
Published: April 2014

Advanced composite materials such as Carbon Fiber Reinforced Plastics (CFRP) are being applied to many aircraft structures in order to improve performance and reduce weight. Most composites have strong, stiff fibers in a matrix which is weaker and less stiff. However, aircraft wings can break due to Fluid-Structure Interaction (FSI) oscillations or material fatigue. This paper focuses on the analysis of a non-linear fluid-structure interaction problem and its solution in the finite element software package DOpElib: the deal.II based optimization library. The principal aim of this research is to explore and understand the behaviour of the fluid-structure interaction during the impact of a deformable material (e.g. an aircraft wing) on air. Here we briefly describe the analysis of incompressible Navier-Stokes and Elastodynamic equations in the arbitrary Lagrangian-Eulerian (ALE) frameworks in order to numerically simulate the FSI effect on a double wedge airfoil. Since analytical solutions are only available in special cases, the equation needs to be solved by numerical methods. This coupled problem is defined in a monolithic framework and fractional-step-θ time stepping scheme are implemented. Spatial discretization is based on a Galerkin finite element scheme. The non-linear system is solved by a Newton method. The implementation using the software library package DOpElib and deal.II serves for the computation of different fluid-structure configurations.
Pre-Yield Shear in Glasses
Authors: Patashinski Alexander
Published: April 2014

A glassy material is treated as a mosaic of soft and hard clusters. Plastic shear under high shear stress takes place in soft clusters as a series of elementary local slip and stick processes; stress-strain relations are discussed in terms of these elementary acts and their activation energies. Two special situations are considered: a glass where the initial distribution of soft clusters is created by damaging irradiation or other factors, and disappears in the process of shear, and a glass where interaction of soft and hard clusters maintains a time-independent distribution of activation energies.
Ergometers Can Now Biomechanically Replicate Straight-Line Floor Wheelchair Propulsion: Three Models Are Presented
Authors: Salimi Zohreh , Ferguson-Pell Martin W.
Published: April 2014

Wheelchair ergometers facilitate wheelchair related studies as they allow controlled experiments to be performed inside the laboratory. However, the results obtained from these experiments are of limited value unless we use wheelchair ergometers that biomechanically represent real-world wheelchair propulsion. We could not find any wheelchair ergometers in the literature to date, that have been validated considering all of these important biomechanical criteria: Velocity and acceleration, force and moment, trunk swing, inertial effect, energy consumption and the resistive force against propulsion.

In this paper we have considered wheelchair propulsion on an ergometer and have compared it to straight-line floor wheelchair propulsion. From equating these two situations, we have found the necessary conditions to meet the above criteria. Finally, we propose three models for a wheelchair ergometer that satisfies these conditions and will be able to biomechanically represent straight-line floor wheelchair propulsion.
Visualization Study of Pool Boiling on Polished and Porous Coated Surfaces for Deionized Water and Al2O3-Water Nano-Fluids
Authors: Niu Gengwen , Li Ji
Published: April 2014

In the present work, pool boiling on copper porous coating and polished surface are studied experimentally at atmospheric pressure to explore the characteristics and the regime of boiling. A high-speed camera (maximum frame rate 10000 fps) with attached magnifying lens allowed precise observation of the incipient nucleation of boiling on the two surfaces. The observed boiling phenomena suggest different characteristics in the wall superheat, the heat transfer coefficient, the departure diameter of the bubble and the frequency of the bubble generation on two substrates for two working medium at different input power. The results indicate that the heat transfer performance is greatly enhanced by using porous coating and nano-fluids. The heat transfer coefficient on the porous coating is three to four times of that on the polished surface. Meanwhile, the temperature at incipience of boiling on the porous coating is lower than that on the polished surface qualitatively for the same working medium. The new contribution of this work is that we combined nano-fluids and porous surface together to explore the heat transfer performance and conducted visual experiments to observe the behavior of the bubbles of this assembly in the pool boiling.
An Electricity and Value-Added Gases Co-Generation via Solid Oxide Fuel Cells
Authors: Wang Kang , Zeng Pingying , Ahn Jeongmin
Published: April 2014

In this study, an electricity and value-added chemicals cogeneration system using methane-fueled single chamber solid oxide fuel cells (SC-SOFCs) was successfully developed and investigated. The SC-SOFCs, which operated on methane/oxygen gas mixture with a ratio of 2:1, achieved an open-circuit voltage of 1.0 V and a maximum peak power density of ∼ 840 mW.cm-2 at 700 °C. By passing the exhaust gas of the fuel cell through a Ru/Al2O3 catalyst at 700 °C, the synthesis gas is obtained with a methane conversion of higher than 95%, while CO and H2 selectivity is higher than 92%. This study provides a novel strategy for energy conversion which is one of the major concerns in energy field and a new frontier for improving the energy efficiency of SOFCs.
LES Investigation of Passive Flow Control Around an Ahmed Body
Authors: Krajnović Siniša
Published: April 2014

Large eddy simulations are used to study passive flow control for drag reduction in a simplified ground vehicle. Add on devices in the form of short cylinders are used for the formation of streaks in the streamwise direction that lead to the separation delay. The results of the present numerical simulations are compared with the experimental data and show good agreement. The two-stage flow control mechanism is analyzed from the LES results. It was found to be in agreement with the previous experimental observations that the counter-rotating vortices behind the impinging devices influence the separation only indirectly through the longitudinal vortices further downstream.
Cryogenic Cooling System “KrioBlast” Increased Efficiency and Lowered the Operation Time of Protective Electrical Induction-Induced Devices
Authors: Bolyukh Vladimir F. , Katkov Igor I.
Published: April 2014

Main electromagnetic and thermal characteristics of cryoresistive windings (CRW) are systematized; and based on these results a mathematical model of an induction-dynamic device (IDD) is developed. Active elements of the IDD are cooled by liquid nitrogen. To calculate the IDD’s working processes a numerical-analytical approach is used. Within a small interval of time analytical expressions for the main values are calculated. The transient process is modeled on a computer program by iterative relations and time loops. In the calculation the IDD’s armature is represented as a set of elementary short-circuited circuits uniformly distributed on a disk’s surface, and the multi-turn inductor is represented by a primary circuit connected to the capacitance energy storage (CES). On the base of the carried out mathematical modeling it is demonstrated that the most effective is the cryogenic cooling of the armature for which a minimal amount of cryogen is required. At the simultaneous cooling of the inductor and the armature the IDD’s efficiency increases 24 times. It is shown that in case of the use of a ferromagnetic core as an alternative to a cryogenic cooling, the IDD’s efficiency increase is much lower. The validity of the proposed mathematical model and obtained numerical results is demonstrated on the base of experimental modeling.
Lattice Boltzmann Method Simulation on Flow Patterns of Natural Convection in Horizontal Cylindrical Annulus
Authors: Yang Mo , Zhou Yuwei , Zhang Yuwen , Bian Enjie , Li Zheng
Published: April 2014

The Lattice Boltzmann method is used to simulate the flow patterns of natural convection in horizontal cylindrical annulus for aspect ratios in the range of 0.4≤A≤10 and for Prandtl numbers varying from 0.1 to 0.7. At Pr = 0.3 and A = 2, flow patterns on the whole range of Rayleigh number are mapped indicating the lower and upper critical values for transitions. At Pr = 0.7, the influence of aspect ratio on flow pattern is analyzed acquiring the result that the oscillation flow never happens at A≤3. At A = 2, several Prandtl numbers are calculated at certain Rayleigh number and the conclusion is that the steady upward flow keeps when 0.5≤Pr. The results are found in good agreement with existed studies.
Deployment Analysis of Deployable Structures Based on Linkages Considering Thermal Effect
Authors: Cai Jian-guo , Feng Jian , Zhao Yao-zong
Published: April 2014

The thermal stress due to temperature rise may increase the element strain and internal forces, which may lead to the failure of the deployment of deployable structure. However, few works are carried out to study the dynamic performance of the flexible multibody under different temperatures, especially for deployable structures that work in space environments. Based on this idea and formulation of finite element methods, the dynamic equations of the system considering the temperature effect are derived. Then two examples, a parallel four-bar linkage and a non-parallel four-bar linkage, are presented in this paper to study the influence of thermal loading on the structural behavior during the motion. The results show that the effect of temperature changes is slight for the parallel four-bar linkage, but the influence is significant for the non parallel four-bar linkage. It can be concluded that the former case may be more suitable for the deployable structures in space environment.
Post-Consumer Plastic Sortation With the Use of Electromagnetic Separation Methods for Recycling
Authors: Kress C. , Franchetti M.
Published: April 2014

In 2010, the United States generated over 31 million tons of plastic waste, and from that total, only 8% was recycled. With demand for lower cost plastics and public attention to environmental concerns increasing, the expanding recycling industry has provided an opportunity to lower raw material costs and create sustainable jobs. Traditionally, manual or optical methods that used infrared technologies were utilized to sort plastic wastes for recycling. Once these plastic wastes were sorted, they were cleaned, shredded, and melted into raw materials. These methods are costly and can experience high nonconformance rates during the sortation processes. This paper discussed an emerging technique that utilizes a novel process that sorts shredded plastic particles by using electromagnetic (EM) waves and Ferro fluids. The process involves placing various types of shredded plastic particles of into a tank filled with Ferro fluid. The plastic particles and Ferro fluid are then subjected to an EM wave by the use of an EM coil. The EM wave alters the viscosity of the Ferro fluid and causes the shredded plastic particles to rise and sink at different vertical levels within the Ferro fluid tank, based on their respective densities. This method allows for an efficient, accurate, and low cost method to sort plastic particles as compared to conventional technologies. Overviews of the model development, experimental design, and test results are provided that demonstrates proof-of-concept. The results of the study indicated that the EM separation method may offer significant cost, efficiency, and accuracy improvements over conventional methods.
Energy Finite Element Analysis of Structural-Solid Domains
Authors: Medyanik S. , Vlahopoulos N. , Lee S.
Published: April 2014

An Energy Finite Element Analysis (EFEA) formulation and implementation for modeling coupled structural-solid domains is presented. Two wave bearing mechanisms are considered within the solid domain, associated with dilatational and distortional deformation. The corresponding space averaged energy densities of these waves comprise the primary variables in the differential equations which are being solved numerically using a finite element approach. Joints are developed between solid elements and the plate elements that facilitate the exchange of power between elements from different wave bearing domains. The power transfer mechanism between each wave type of the solid domain and the bending behavior of the plate is considered separately. The corresponding power transfer coefficients are derived based on a radiation efficiency model between the bending waves of the plate and each one of the waves in the solid domain. Results are validated by comparison to traditional FEA solution, which reveals good agreement between the two approaches. This development targets analysis of tubular members which are filled with solid type of material and would allow for determining the appropriate properties of the solid material that can increase the attenuation of vibration in the tubular members.
Computational Fluid Dynamics Analysis of Blood Flow Through Stented Arteries
Authors: Mohammad Shafiullah , Majumdar Pradip
Published: April 2014

Atherosclerosis is a vascular disease that reduces arterial lumen size through plaque deposition and arterial wall thickening. The pathological complications of atherosclerosis, namely heart disease and stroke, remain the leading cause of mortality in the world. The most common interventional procedure against atherosclerosis involves the placement of an intravascular stent. Intravascular stents are small tube like structures placed into Stenotic arteries to restore the blood flow. In this study CFD analysis is performed on the femoral artery by considering blood flow as a pulsating, incompressible and Newtonian flow over a realistic velocity waveform of the femoral artery. The artery is considered as a rigid and straight with a branch. The governing transient Navier-Stokes equations are solved using commercial software code Star-CCM+. Simulations are performed on healthy, atherosclerosis affected and Stented femoral arteries. Velocity and wall shear stress fields over the cardiac cycle are analyzed to predict the outcome of the interventions in terms of recirculation and stagnation regions and identify improved stent designs. The flow patterns in the arteries are highly modulating along with the cardiac cycle and a strong function of the waveform created by the heartbeat. The complex blood flow pattern with slow moving regions, flow separation and recirculatory form near the wall during cardiac cycle is the major contributing factor to the formation of the atherosclerotic plaque at that location. It was demonstrated that adverse flow field created upstream and downstream of the blockage may cause enhanced growth in size of the blockage. The stent design also plays significant role in the possibility of restenosis.