bluuebunny/crossref_metadata_2025 huggingface dataset:
Neighbourhood social capital: measurement issues and associations with health outcomes
Authors: Mackenbach J. D. , Lakerveld J. , van Lenthe F. J. , Kawachi I. , McKee M. , Rutter H. , Glonti K. , Compernolle S. , De Bourdeaudhuij I. , Feuillet T. , Oppert J.‐M. , Nijpels G. , Brug J.
Published: February 2016

We compared ecometric neighbourhood scores of social capital (contextual variation) to mean neighbourhood scores (individual and contextual variation), using several health‐related outcomes (i.e. self‐rated health, weight status and obesity‐related behaviours).

Data were analysed from 5,900 participants in the European SPOTLIGHT survey. Factor analysis of the 13‐item social capital scale revealed two social capital constructs: social networks and social cohesion. The associations of ecometric and mean neighbourhood‐level scores of these constructs with self‐rated health, weight status and obesity‐related behaviours were analysed using multilevel regression analyses, adjusted for key covariates.

Analyses using ecometric and mean neighbourhood scores, but not mean neighbourhood scores adjusted for individual scores, yielded similar regression coefficients. Higher levels of social network and social cohesion were not only associated with better self‐rated health, lower odds of obesity and higher fruit consumption, but also with prolonged sitting and less transport‐related physical activity. Only associations with transport‐related physical activity and sedentary behaviours were associated with mean neighbourhood scores adjusted for individual scores.

As analyses using ecometric scores generated the same results as using mean neighbourhood scores, but different results when using mean neighbourhood scores adjusted for individual scores, this suggests that the theoretical advantage of the ecometric approach (i.e. teasing out individual and contextual variation) may not be achieved in practice. The different operationalisations of social network and social cohesion were associated with several health outcomes, but the constructs that appeared to represent the contextual variation best were only associated with two of the outcomes.
Mismatch between perceived and objectively measured environmental obesogenic features in European neighbourhoods
Authors: Roda C. , Charreire H. , Feuillet T. , Mackenbach J. D. , Compernolle S. , Glonti K. , Ben Rebah M. , Bárdos H. , Rutter H. , McKee M. , De Bourdeaudhuij I. , Brug J. , Lakerveld J. , Oppert J.‐M.
Published: February 2016

Findings from research on the association between the built environment and obesity remain equivocal but may be partly explained by differences in approaches used to characterize the built environment. Findings obtained using subjective measures may differ substantially from those measured objectively. We investigated the agreement between perceived and objectively measured obesogenic environmental features to assess (1) the extent of agreement between individual perceptions and observable characteristics of the environment and (2) the agreement between aggregated perceptions and observable characteristics, and whether this varied by type of characteristic, region or neighbourhood. Cross‐sectional data from the SPOTLIGHT project (n = 6037 participants from 60 neighbourhoods in five European urban regions) were used. Residents' perceptions were self‐reported, and objectively measured environmental features were obtained by a virtual audit using Google Street View. Percent agreement and Kappa statistics were calculated. The mismatch was quantified at neighbourhood level by a distance metric derived from a factor map. The extent to which the mismatch metric varied by region and neighbourhood was examined using linear regression models. Overall, agreement was moderate (agreement < 82%, kappa < 0.3) and varied by obesogenic environmental feature, region and neighbourhood. Highest agreement was found for food outlets and outdoor recreational facilities, and lowest agreement was obtained for aesthetics. In general, a better match was observed in high‐residential density neighbourhoods characterized by a high density of food outlets and recreational facilities. Future studies should combine perceived and objectively measured built environment qualities to better understand the potential impact of the built environment on health, particularly in low residential density neighbourhoods.
Self‐defined residential neighbourhoods: size variations and correlates across five European urban regions
Authors: Charreire H. , Feuillet T. , Roda C. , Mackenbach J. D. , Compernolle S. , Glonti K. , Bárdos H. , Le Vaillant M. , Rutter H. , McKee M. , De Bourdeaudhuij I. , Brug J. , Lakerveld J. , Oppert J.‐M.
Published: February 2016

The neighbourhood is recognized as an important unit of analysis in research on the relation between obesogenic environments and development of obesity. One important challenge is to define the limits of the residential neighbourhood, as perceived by study participants themselves, in order to improve our understanding of the interaction between contextual features and patterns of obesity. An innovative tool was developed in the framework of the SPOTLIGHT project to identify the boundaries of neighbourhoods as defined by participants in five European urban regions. The aims of this study were (i) to describe self‐defined neighbourhood (size and overlap with predefined residential area) according to the characteristics of the sampling administrative neighbourhoods (residential density and socioeconomic status) within the five study regions and (ii) to determine which individual or/and environmental factors are associated with variations in size of self‐defined neighbourhoods. Self‐defined neighbourhood size varies according to both individual factors (age, educational level, length of residence and attachment to neighbourhood) and contextual factors. These findings have consequences for how residential neighbourhoods are defined and operationalized and can inform how self‐defined neighbourhoods may be used in research on associations between contextual characteristics and health outcomes such as obesity.
Oral epithelial cells and their interactions with HIV‐1
Authors: Moyes DL , Islam A , Kohli A , Naglik JR
Published: February 2016

As the AIDS pandemic has continued, our understanding of the events that occur during the entry and infection of conventional, susceptible cells has increased dramatically, leading to the development of control therapies for HIV‐infected individuals. However, an ongoing hole in our understanding is how HIV crosses the mucosal barriers to gain access to permissive cells, despite how important this information would be in developing successful vaccines and other preventative measures such as topical anti‐HIV microbicides. In particular, our knowledge of the role that epithelial cells of the mucosal surfaces play in infection – both during early phases and throughout the life of an infected individual, is currently hazy at best. However, several studies in recent years suggest that HIV can bind to and traverse these mucosal epithelial cells, providing a reservoir of infection that can subsequently infect underlying permissive cells. Despite this interaction with epithelial cells, evidence suggests HIV‐1 does not productively infect these cells, although they are capable of transferring surface‐bound and transcytosed virus to other, permissive cells. Further, there appear to be key differences between adult and infant epithelial cells in the degree to which HIV can transcytose and infect the epithelium. Thus, it is clear that, whilst not primary targets for infection and virus replication, epithelial cells play an important role in the infection cycle and improving our understanding of their interactions with HIV could potentially provide key insights necessary to develop effective preventative therapies.
Isolated Disruption of the Right Coronary Artery Following a Steam Pop during Cavotricuspid Linear Ablation with a Contact Force Catheter
Authors: BRUNELLI MICHELE , FROMMHOLD MARKUS , BACK DIETER , MIERZWA MARCO , LAUER BERNARD , GELLER J. CHRISTOPH
Published: February 2016

A 70‐year‐old woman with persistent atrial fibrillation underwent pulmonary vein isolation and linear ablation with a contact sensor catheter. During cavotricuspid isthmus ablation, a steam pop resulted in cardiac tamponade, and the patient developed severe hypotension despite successful pericardial puncture and minimal residual pericardial effusion. Right coronary artery angiography revealed extravasal contrast medium accumulation posterior of the Crux Cordis. Emergent cardiac surgery confirmed isolated disruption of the artery in the absence of additional heart perforation. Although contact sensor catheters may reduce complications, steam pops can still occur and result in dramatic complications.
Maize yield improvements in China: past trends and future directions
Authors: Qin Xiaoliang , Feng Fan , Li Yajun , Xu Shutu , Siddique Kadambot H. M. , Liao Yuncheng
Published: February 2016

Maize is one of China's most important grain crops. We analysed data from breeding trials and experimental reports to assess genetic gains in the single‐cross varieties in terms of grain yield and agronomic traits in Northern China, Southwestern China and Yellow–Huai River Valley. Since the 1960s, the grain yield of single‐cross varieties has increased linearly in all three regions. Plant height, ear rows and 100‐seed weight have increased linearly (P < 0.05) with time, while ear length has decreased (P < 0.05). Planting density has increased (P < 0.05) in Yellow–Huai River Valley and Northern China, but no change in Southwestern China. Ear height and leaf number in Northern China and Southwestern China have increased linearly (P < 0.05) over time, but no change in Yellow–Huai River Valley. The growing period in Yellow–Huai River Valley has increased linearly (P < 0.05), while that of Northern China and Southwestern China has not changed. Our analysis showed that contribution of agronomic traits to grain yield differed between agroecological regions. Future research and breeding strategies should focus on specific agroecological regions.
Physiological and molecular mechanisms mediating xylem Na+ loading in barley in the context of salinity stress tolerance
Authors: Zhu Min , Zhou Meixue , Shabala Lana , Shabala Sergey
Published: February 2016

Time‐dependent kinetics of xylem Na+ loading was investigated using a large number of barley genotypes contrasting in their salinity tolerance. Salt‐sensitive varieties were less efficient in controlling xylem Na+ loading and showed a gradual increase in the xylem Na+ content over the time. To understand underlying ionic and molecular mechanisms, net fluxes of Ca2+, K+ and Na+ were measured from the xylem parenchyma tissue in response to H2O2 and ABA; both of them associated with salinity stress signalling. Our results indicate that NADPH oxidase‐mediated apoplastic H2O2 production acts upstream of the xylem Na+ loading and is causally related to ROS‐inducible Ca2+ uptake systems in the root stelar tissue. It was also found that ABA regulates (directly or indirectly) the process of Na+ retrieval from the xylem and the significant reduction of Na+ and K+ fluxes induced by bumetanide are indicative of a major role of chloride cation co‐transporter (CCC) on xylem ion loading. Transcript levels of HvHKT1;5_like and HvSOS1_like genes in the root stele were observed to decrease after salt stress, while there was an increase in HvSKOR_like gene, indicating that these ion transporters are involved in primary Na+/K+ movement into/out of xylem.
Complexity, Capacity, and Budget Punctuations
Authors: Epp Derek A. , Baumgartner Frank R.
Published: February 2016

The budgeting literature has long focused on “institutional friction” as a cause of ubiquitous punctuated equilibrium (PE) findings. A recent wave of scholarship looks to identify specific institutional mechanisms that affect the number of punctuations in policy outputs. We contribute to this growing body of research by focusing on the complexity of the institutional environment surrounding a policy area as well as that of the government as a whole. These factors have opposite effects: the more complex a policy area, the greater the likelihood of extreme spending changes. But, higher institutional capacity in general leads to greater stability. To test these ideas, we develop a novel index of budgetary change that balances the conceptual importance of extreme changes while analyzing the entire distribution of budget changes, not only the tails. In addition, we also demonstrate that findings are robust to a number of important distinctions, such as between series associated with slowly moving demographic trends or quickly moving stochastic events. We, therefore, demonstrate the robustness of important findings from the established literature, add a new measure of the dependent variable, and push the literature forward with a new focus on issue complexity and institutional capacity.
The RDoC initiative and the structure of psychopathology
Authors: Krueger Robert F. , DeYoung Colin G.
Published: February 2016

The NIMH Research Domain Criteria (RDoC) project represents a welcome effort to circumvent the limitations of psychiatric categories as phenotypes for psychopathology research. Here, we describe the hierarchical and dimensional structure of phenotypic psychopathology and illustrate how this structure provides phenotypes suitable for RDoC research on neural correlates of psychopathology. A hierarchical and dimensional approach to psychopathology phenotypes holds great promise for delineating connections between neuroscience constructs and the patterns of affect, cognition, and behavior that constitute manifest psychopathology.
Review of Research Trends and Methods in Nano Environmental, Health, and Safety Risk Analysis
Authors: Erbis Serkan , Ok Zeynep , Isaacs Jacqueline A. , Benneyan James C. , Kamarthi Sagar
Published: February 2016

Despite the many touted benefits of nanomaterials, concerns remain about their possible environmental, health, and safety (EHS) risks in terms of their toxicity, long‐term accumulation effects, or dose‐response relationships. The published studies on EHS risks of nanomaterials have increased significantly over the past decade and half, with most focused on nanotoxicology. Researchers are still learning about health consequences of nanomaterials and how to make environmentally responsible decisions regarding their production. This article characterizes the scientific literature on nano‐EHS risk analysis to map the state‐of‐the‐art developments in this field and chart guidance for the future directions. First, an analysis of keyword co‐occurrence networks is investigated for nano‐EHS literature published in the past decade to identify the intellectual turning points and research trends in nanorisk analysis studies. The exposure groups targeted in emerging nano‐EHS studies are also assessed. System engineering methods for risk, safety, uncertainty, and system reliability analysis are reviewed, followed by detailed descriptions where applications of these methods are utilized to analyze nanomaterial EHS risks. Finally, the trends, methods, future directions, and opportunities of system engineering methods in nano‐EHS research are discussed. The analysis of nano‐EHS literature presented in this article provides important insights on risk assessment and risk management tools associated with nanotechnology, nanomanufacturing, and nano‐enabled products.
Nonlinear Wave–Current Interactions in Shallow Water
Authors: Lannes David , Marche Fabien
Published: February 2016

We study here the propagation of long waves in the presence of vorticity. In the irrotational framework, the Green–Naghdi equations (also called Serre or fully nonlinear Boussinesq equations) are the standard model for the propagation of such waves. These equations couple the surface elevation to the vertically averaged horizontal velocity and are therefore independent of the vertical variable. In the presence of vorticity, the dependence on the vertical variable cannot be removed from the vorticity equation but it was however shown in that the motion of the waves could be described using an extended Green–Naghdi system. In this paper, we propose an analysis of these equations, and show that they can be used to get some new insight into wave–current interactions. We show in particular that solitary waves may have a drastically different behavior in the presence of vorticity and show the existence of solitary waves of maximal amplitude with a peak at their crest, whose angle depends on the vorticity. We also show some simple numerical validations. Finally, we give some examples of wave–current interactions with a nontrivial vorticity field and topography effects.
Moving boulders in flash floods and estimating flow conditions using boulders in ancient deposits
Authors: Alexander Jan , Cooker Mark J.
Published: February 2016

Boulders moving in flash floods cause considerable damage and casualties. More and bigger boulders move in flash floods than predicted from published theory. The interpretation of flow conditions from the size of large particles within flash flood deposits has, until now, generally assumed that the velocity (or discharge) is unchanging in time (i.e. flow is steady), or changes instantaneously between periods of constant conditions. Standard practice is to apply theories developed for steady flow conditions to flash floods, which are however inherently very unsteady flows. This is likely to lead to overestimates of peak flow velocity (or discharge). Flash floods are characterised by extremely rapid variations in flow that generate significant transient forces in addition to the mean‐flow drag. These transient forces, generated by rapid velocity changes, are generally ignored in published theories, but they are briefly so large that they could initiate the motion of boulders. This paper develops a theory for the initiation of boulder movement due to the additionalimpulsive forcegenerated by unsteady flow, and discusses the implications.
Social and emotional self‐efficacy at work
Authors: Loeb Carina , Stempel Christiane , Isaksson Kerstin
Published: February 2016

Research has shown that self‐efficacy is often one of the most important personal resources in the work context. However, because this research has focused on cognitive and task‐oriented self‐efficacy, little is known about social and emotional dimensions of self‐efficacy at work. The main aim of the present study was to investigate social and emotional self‐efficacy dimensions at work and to compare them to a cognitive and task‐oriented dimension. Scales to measure social and emotional self‐efficacy at work were developed and validated and found to be well differentiated from the cognitive task‐oriented occupational self‐efficacy scale. Confirmatory factor analyses of data from 226 Swedish and 591 German employees resulted in four separate but correlated self‐efficacy dimensions: (1) occupational; (2) social; (3) self‐oriented emotional; and (4) other‐oriented emotional. Social self‐efficacy explained additional variance in team climate and emotional self‐efficacy in emotional irritation and emotional exhaustion, over and above effects of occupational self‐efficacy. Men reported higher occupational self‐efficacy, whereas social and emotional self‐efficacy revealed no clear gender differences. The scales have strong psychometric properties in both Swedish and German language versions. The positive association between social self‐efficacy and team climate, and the negative relationships between self‐oriented emotional self‐efficacy and emotional irritation and emotional exhaustion may provide promising tools for practical applications in work settings such as team‐building, staff development, recruitment or other training programs aiming for work place health promotion. The next step will be to study how social and emotional self‐efficacy relate to leadership, well‐being and health over time.
Observed Emotions as Predictors of Quality of Kindergartners’ Social Relationships
Authors: Hernández Maciel M. , Eisenberg Nancy , Valiente Carlos , Spinrad Tracy L. , VanSchyndel Sarah K. , Diaz Anjolii , Silva Kassondra M. , Berger Rebecca H. , Southworth Jody
Published: February 2016

This study evaluated whether positive and anger emotional frequency (the proportion of instances an emotion was observed) and intensity (the strength of an emotion when it was observed) uniquely predicted social relationships among kindergarteners (N = 301). Emotions were observed as naturally occurring at school in the fall term and multiple reporters (peers and teachers) provided information on quality of relationships with children in the spring term. In structural equation models, positive emotion frequency, but not positive emotion intensity, was positively related to peer acceptance and negatively related to peer rejection. In contrast, the frequency of anger provided unique positive prediction of teacher–student conflict and negative prediction of peer acceptance. Furthermore, anger intensity negatively predicted teacher–student closeness and positively predicted teacher–student conflict. Implications for promoting social relationships in school are discussed.
OPTIMIZATION OF ENERGY USE INTENSITY USING DATA ENVELOPMENT ANALYSIS AND BENCHMARKING METHODOLOGY FOR SUSTAINABLE RICE CULTIVATION UNDER WETLAND DIRECT SEEDING CONDITIONS IN MALAYSIA
Authors: Muazu Aliyu , Yahya Azmi , Wan Ishak Wan Ismail , Bejo Siti Khairunniza
Published: February 2016

Rice is tan important crop and main staple food In Malaysia, The country typically produces about two third of its total requirements with the balance met through import. The imported rice cost less compared to the same grade produce locally. One way to reduce production cost is by improving energy use intensity through optimum use of farm inputs. In this study we investigated the energy use intensity of 40 farms that practices direct seeding system of wetland rice cultivation in Malaysia. At mean yield level of 7,630 kg/ha, the optimum energy use intensity was 1.73 MJ/kg which is lower compared to the energy use intensities in efficient farms, all farms, and the inefficient farms by about 3%, 18% and 26% respectively. Three efficient farms identified as having the highest reference frequency in the study area had a mean yield level of 8,723 kg/ha and a mean energy productivity of 0.642 kg/MJ which were found to be about 1,368 kg/ha (19%) and 0.201 kg/MJ (46%), respectively higher than the mean yield and energy productivity in the inefficient farms. An average farmer in the study area used about 2,914 MJ/ha of energy in excess of the optimum level, representing RM626/ha in lost revenues.
SUITABILITY OF CAPSULE AS A PADDY COATING MATERIAL FOR THE SYSTEM OF RICE INTENSIFICATION (SRI)
Authors: Abdulkadir Tukur Daiyabu , Wan Ismail Wan Ishak , Mohd Kasim Muhammad Saufi , Bejo Siti Khairunniza
Published: February 2016

One of the challenges faced by farmers in adopting the system of rice intensification is the seed establishment required high labor demand. This research aims at providing an alternative to seedling transplanting for the system of rice intensification. In this research the paddy seed was enhanced with the use of pharmaceutical capsule as a seed coating material for ease of seed singulation and suitability in handling by a conventional direct seeding technique. It covers the study of capsules as a suitable paddy seed coating material. The solubility of starch and gelatin capsules in water was studied at three different temperatures of 25oC, 35oC, and 45oC. Three paddy seed treatments of dry seeds, primed seed, and pre germinated were each placed in to the capsule at the ratio of 1:1 and planted in the soil with three replications. The planted seeds were irrigated two times daily for a period of 10 days within which the germination and emergence were recorded on daily bases. Gelatin capsule was found to be soluble in water at temperature of 45oC and above. Starch capsule on the other hand was found to be soluble at temperatures of 25oC which made it the more suitable paddy coating material in comparison with the gelatin capsule. The germination and emergence results of starch capsule coated paddy were found to be 95%, 83%, and 58% for the pre germinated, primed, and dry paddy seeds respectively.
INITIAL DESIGN OF AN AUTOMATED SYSTEM FOR PADDY SEEDLING PLACEMENT IN A GERMINATION TRAY
Authors: Mohd Rosli Muhammad Firdaus , Mahadi Muhammad Razif , Misri Muhammad Afiq , Wayayok Aimrun
Published: February 2016

Domestic demand for rice in Malaysia is more than the amount of local production; hence extra supplies are imported from neighbouring countries. For self-sustenance and food security, the government has targeted for a rise in the domestic rice production. Since conventional practice depends on labour, further mechanization is needed in order to achieve the goal. Inspired by the government policy, mechanization system based on System of Rice Intensification (SRI) has been developed and actively researched at the Universiti Putra Malaysia (UPM). One of the efforts is the design of a specialized seedling germination tray, which has been successfully patented. As part of further development program, an automated system for paddy seedling placement is currently developed. The system resembled a conveyor system with instrumentation for controlling the motion and placement of the seeding tray. Based on the result obtained, the conveyor was able to achieve start-stop distance at 16.98 mm if the time-delay variable was set at 100 ms. This paper presents the initial design development of the device. The machine was developed based the specification derived from the tray.
Development of a Circular Thermoelectric Skutterudite Couple Using Compression Technology
Authors: Mansouri Nariman , Timm Edward J. , Schock Harold J. , Sahoo Dipankar , Kotrba Adam
Published: February 2016

Approximately, 55% of the energy produced from conventional vehicle resources is lost due to heat losses. An efficient waste heat recovery process will lead to improved fuel efficiency and greenhouse gas emissions. Thermoelectric generators (TEGs) are heat recovery devices that are being widely studied by a range of energy-intensive industries. Efficient solid-state thermoelectric devices are good candidates to reduce fuel consumption in an automobile. Thermoelectric materials have had limited automotive applications due to the automotive waste heat recovery temperature range, the rarity and toxicity of some materials, and the limited ability to mass manufacture thermoelectric devices from expensive TE materials. However, skutterudite is one class of material that has demonstrated significant promise in the transportation waste heat recovery temperature domain. Durability and reliability of the TEGs are the most significant concerns in the product development process. Cracking of the materials at hot-side interface is found to be a major failure mechanism of TEGs under thermal loading. Cracking affects not only the structural integrity but also the energy conversion and overall performance of the system. In this paper, cracking of thermoelectric material as observed in performance testing is analyzed using numerical simulations and analytic experiments. This paper shows, with the help of finite element analysis (FEA), the detailed distribution of stress, strain, and temperature is obtained for each design. Finite element (FE)-based simulations show the tensile stresses as the primary factor causing radial and circumferential cracks in the skutterudite. For a TEG design, loading conditions and closed-form analytical solutions of stress/strain distributions are derived. Scenarios with minimum tensile stresses are sought. These approaches yield the minimum of stress/strain fields which produce cracks. Finally, based on these analyses and computational fluid dynamics (CFD) studies, strategies in tensile stress reduction and failure prevention are proposed.
Development of a New Model for Carbonate Matrix Acidizing to Consider the Effects of Spent Acid
Authors: Bastami Alireza , Pourafshary Peyman
Published: February 2016

Carbonate matrix acidizing is widely used in oil fields as a simple and easy method of production enhancement. However, the dissolution pattern created due to the reaction between the acid and the carbonates is a complex phenomenon. Several experimental and modeling studies have been carried out to simplify this process and design the optimum conditions for acidizing. One approach is to develop continuum models to simulate the dissolution process in the core scale. Conventional modeling approaches typically do not consider the effects of spent acid in the models. However, there are a few studies and observations on the solubility of CO2 in the CaCl2-H2O-CO2 system, which shows the possibility of formation of a separate CO2 phase during acidizing. The presence of CO2 as a separate phase affects the dominant wormhole propagation and also the dissolution regime. Moreover, the acid/rock reaction leads to the change of physical properties of the flowing fluid. Hence, neglecting the alterations in the physical properties of the moving fluid, such as density and viscosity, affects the accuracy of the models. In this study, a basic model previously introduced in the Darcy scale is developed to consider the effect of reaction products on the overall acidizing performance. A thermodynamic model is used to estimate the CO2 solubility in the spent acid. The insoluble CO2 may change the relative permeability of the reactants and influence on the optimum conditions. Furthermore, the physical properties of the fluid are estimated and updated at each step of the modeling. Consideration of the spent acid effects in the modeling can improve the modeling accuracy. The developed model has the ability to consider the effect of pressure and temperature of the medium on the optimum conditions. In addition, the developed model has shown better predictions by considering the physical changes during the dissolution.
Modeling Forced Convection Nanofluid Heat Transfer Using an Eulerian–Lagrangian Approach
Authors: Sonawane Sandipkumar , Bhandarkar Upendra , Puranik Bhalchandra
Published: February 2016

An Eulerian–Lagrangian model is used to simulate turbulent-forced convection heat transfer in internal flow using dilute nanofluids. For comparison, a single-phase model of the nanofluid which describes a nanofluid as a single-phase fluid with appropriately defined thermophysical properties is also implemented. The Eulerian–Lagrangian model, which requires only the properties of the base fluid and nanoparticles separately, is seen to predict the heat transfer characteristics accurately without resort to any models for the thermophysical properties. The simulations with the single-phase model show that it can very well be used to predict the heat transfer behavior of dilute nanofluids as long as the thermophysical properties are directly those measured experimentally or those predicted from a Brownian motion based model. These approaches are particularly useful for engineering estimation of heat transfer performance of equipment where nanofluids are expected to be used.
Thermal Conductivity of Suspensions Based on Core–Shell Particles
Authors: Sukhinin G. I. , Serebryakova M. A. , Novopashin S. A.
Published: February 2016

An analytical solution of the problem of the thermal conductivity of a suspension containing core–shell particles was found. Solutions were found under the thickness of the shell tending to zero while the thermal conductivity of the shell was tending to zero and infinity. In the first case, the solution is shown to be equivalent to the solution that takes into account Kapitza interfacial thermal resistance. The role of contact Kapitza resistance in the processes of the thermal conduction of nanofluids is discussed.
Control-Oriented Model of Atkinson Cycle Engine With Variable Intake Valve Actuation
Authors: Murtaza G. , Bhatti A. I. , Ahmed Q.
Published: February 2016

With the advancement in the innovated technologies, optimum efficiency of spark ignition (SI) engine can be accomplished during the entire engine operating range, particularly at part load. In this research, a novel control-oriented extended mean value engine model (EMVEM) of the Atkinson cycle engine is proposed, wherein the Atkinson cycle, variable valve timing (VVT), overexpansion, and variable compression ratio (VCR) characteristics are incorporated. For this purpose, an intake valve timing (IVT) parameter is introduced, which has a vital role in modeling the inclusive dynamics of the system and to deal with engine performance degrading aspects. The proposed model is validated with the experimental data of a VVT engine, obtained from literature, to ensure that the proposed model has the capability to capture the dynamics of the Atkinson cycle engine, and engine load can be controlled by IVT parameter, instead of the conventional throttle. The potential benefits of late intake valve closing (LIVC) tactic and copious integrated characteristics are appreciated as well. Furthermore, simulation results of the developed model primarily indicate the reduction in the engine part load losses and enhancement in thermal efficiency due to overexpansion, which has a great significance in the enhancement of the performance, fuel economy, and emissions reduction. Besides, the constraints on LIVC and overexpansion become evident.
Experimental Study of Pressure Drop-Flow Rate Characteristics of Heated Tight Porous Materials
Authors: Liao Yuxuan , Li Xin , Zhong Wei , Tao Guoliang , Liu Hao , Kagawa Toshiharu
Published: February 2016

Tight porous materials are used as pneumatic components in a wide range of industrial applications. Such porous materials contain thousands of interconnected irregular micropores, which produce a large pressure drop (ΔP) between the upstream and downstream sides of the porous material when a fluid flows through it. The relationship between the pressure drop and flow rate (i.e., ΔP-G characteristics) is a very important basic characteristic. Temperature is one of the factors that affect the ΔP-G characteristics because variations in temperature change the viscosity and density of the fluid. In this study, we experimentally analyzed the ΔP-G characteristics of tight porous materials by heating them using an electromagnetic system. First, we experimentally investigated the change in the ΔP-G curve under the condition of constant heating power. Then, based on the Darcy–Forchheimer theory, we introduced an experimental method to determine the average temperature of the fluid. The results show that the temperature reaches approximately 500 K in the small flow rate range, which produces considerable changes in the ΔP-G curve. As the flow rate increases, the temperature decreases, and thus, the ΔP-G curve at constant heating power converges to the curve for the room temperature. Furthermore, we compared three porous materials with different permeability coefficients and porosities and analyzed the effect of these parameters on the ΔP-G characteristics. We also performed experiments at different downstream pressures to study the effect of the average density on the ΔP-G characteristics.
Influence of Changes in Pressure and Temperature of Supercritical Water on the Susceptibility to Stress Corrosion Cracking of 316L Austenitic Stainless Steel
Authors: Sáez-Maderuelo Alberto , Gómez-Briceño Dolores , Maffiotte César
Published: February 2016

The supercritical water reactor (SCWR) is one of the Generation IV designs. The SCWR is characterized by its high efficiency, low waste production, and simple design. Despite the suitable properties of supercritical water as a coolant, its physicochemical properties change sharply with pressure and temperature in the supercritical region. For this reason, there are many doubts about how changes in these variables affect the behavior of the materials to general corrosion or to specific types of corrosion such as stress corrosion cracking (SCC). Austenitic stainless steels are candidate materials to build the SCWR due to their optimum behavior in the light water reactors (LWRs). Nevertheless, their behavior under the SCWR conditions is not well known. First, the objective of this work was to study the SCC behavior of austenitic stainless steel 316 type L in deaerated supercritical water at 400°C/25  MPa and 30 MPa and 500°C/25  MPa to determine how variations in pressure and temperature influence its behavior with regard to SCC and to make progress in the understanding of mechanisms involved in SCC processes in this environment. Second, the oxide layer formed at 400°C/30  MPa/<10  ppb O2 was analyzed to gain some insight into these processes.
Diagnostics and Life-Cycle Assessment of Medium-Voltage Cables in Nuclear Power Plants During Regular Overhaul Process
Authors: Podkoritnik Simon , Jansa Marko , Manojlovic Stanko
Published: February 2016

The reliability of operation of a nuclear power plant substantially depends on the reliability of its individual components. Electric cables, particularly medium-voltage cables, represent an important constituent of the nuclear island as well as of the balance of the plant. It cannot be considered as satisfactory that the redundancy of a particular subsystem is ensured. For this purpose, it is important to check the cable insulation condition, which is supposed to be carried out during the overhaul activities. The lifetime of medium-voltage cables is estimated to attain somewhere around 40 years. However, due to electrical, thermal, and mechanical stresses, it may be significantly reduced. In order to avoid its likely failures and following outages, the insulation must be tested regularly. Based on obtained testing results, the condition of a cable or cable termination can be assessed and repaired or a replacement made, if necessary. The paper presents some of the most important nondestructive diagnostic measurements on cable connections recommended to be done during the overhaul of a nuclear power plant following a good practice of asset maintenance management.
A Viscoelastic-Elastoplastic Finite Strain Framework for Modeling Polymers
Authors: Lapczyk Ireneusz , Hurtado Juan A.
Published: February 2016

In this paper we present a new constitutive framework, the Parallel Rheological Framework (PRF), for modeling polymers that has been recently developed by the authors and implemented in the commercial finite element software Abaqus [1]. The framework is based on parallel finite-strain viscoelastic and elastoplastic networks. For each viscoelastic network a multiplicative split of the deformation gradient into elastic and viscous components is assumed. The evolution of the viscous component of the deformation gradient is governed by a flow rule obtained assuming the existence of a creep potential. The flow rule is expressed as a function of stress invariants and internal variables, and different evolution laws for the internal variables are allowed within the framework of the model. Similar to the viscoelastic networks, the deformation gradient in the elastoplastic network is decomposed into elastic and plastic components. The yield surface is defined assuming combined isotropic/kinematic hardening. The yield surface is a function of a scalar internal variable that describes isotropic hardening, and a tensorial internal variable (backstress) that describes the shift of the yield surface in the stress space. The evolution of the scalar variable is governed by associated flow rule, while the evolution of backstresses is determined by the Armstrong-Frederick law [2], which is extended to finite-strain deformations. Finally, stress softening is introduced into an elastoplastic network using a modified version of Ogden and Roxbourgh’s pseudo-elasticity model [3].

This paper presents an outline of the framework, including two recent enhancements: a new creep model (the power law model) and combined isotropic/kinematic hardening plasticity model. The framework is then applied to analyze numerically the uniaxial loading/unloading behaviors of filled natural rubber and an EPDM polymer. The results obtained using finite element simulations show very good correlation with experimental data.
Ultrasound Characterization of IM7/PEEK Composite Materials
Authors: Du Jikai , Ladd Katrina M. , Delfanian Fereidoon
Published: February 2016

IM7/PEEK composite materials may experience large mechanical and thermal stresses during service, and their failure mechanisms can be complex and have various modes. In this study, IM7/PEEK specimens for interlaminar shear strength testing were evaluated by both nondestructive ultrasound method and standard destructive test. First, IM7/PEEK specimens were fabricated under various processing parameters including roller speed, torch temperature, roller temperature, compaction level, N2 flow rate, and material tension level. Then ultrasound longitudinal wave velocity that is normal to fiber direction was evaluated and the influence of measuring locations and ultrasound frequencies from 0.5 MHz to 10.0 MHz were studied. Experimental results showed that 5.0 MHz is the most sensitive frequency to fabrication conditions and that ultrasound velocity can be related to some processing parameters such as materials tension, N2 flow rate and temperature. Finally, interlaminar shear strength experiments were carried out by standard short beam bending destructive tests. The relationship between ultrasound velocity and standard destructive tests were analyzed and the potential of ultrasound velocity for interlaminar shear strength evaluation was discussed.
Effect of Microvoids on Anomalous Moisture Absorption of Quartz/BMI Composite Laminates
Authors: Hurdelbrink Keith R. , Guloglu Gorkem E. , Anderson Jacob P. , Grace Landon R. , Siddique Zahed , Altan M. Cengiz
Published: February 2016

The focus of this paper was to investigate the effects of microvoid content in quartz/BMI laminates on both short and long-term moisture absorption dynamics. The moisture absorption characteristics for the laminates were experimentally obtained by water immersion tests at 25°C of three-ply quartz/BMI samples that contain voids, ranging from 8.6% to 13.7% by volume. The void levels were obtained by conditioning the prepreg at different moisture levels for 48 hours in an environmental chamber before curing in a hot press. The curing process was carried out at 69 kPa, which leads to a more uniform fiber volume fraction for the laminates. Having a constant fiber volume fraction ensures the same amount of fiber-matrix interface present in all the test samples, therefore eliminating the effect of fiber-matrix interface as an experimental variable. It is shown that the presence of microvoids leads to an increased non-Fickian absorption behavior. Hence, the anomalous, non-Fickian absorption parameters are obtained by using a one-dimensional absorption model that accounts for both bound and unbound free water within the laminate. It is shown that the microvoids act as storage sites for moisture which can be described by the one-dimensional, non-Fickian absorption model. Finally, possible relationships between the four absorption model parameters and the process-induced microvoid content are discussed.
A Multiscale Computational Model for the Growth of the Cranial Vault in Craniosynostosis
Authors: Lee Chanyoung , Richtsmeier Joan T. , Kraft Reuben H.
Published: February 2016

Craniosynostosis is a condition defined by premature closure of cranial vault sutures, which is associated with abnormalities of the brain and skull. Many causal relationships between discovered mutations and premature suture closure have been proposed but an understanding of the precise mechanisms remains elusive. This article describes a computational framework of biological processes underlying cranial growth that will enable a hypothesis driven investigation of craniosynostosis phenotypes using reaction-diffusion-advection methods and the finite element method. Primary centers of ossification in cranial vault are identified using an activator-substrate model that represents the behavior of key molecules for bone formation. Biomechanical effects due to the interaction between growing bone and soft tissue is investigated to elucidate the mechanism of growth of cranial vault.
Step-by-Step Simplification of the Micropolar Elasticity Theory to the Couple-Stress and Classical Elasticity Theories
Authors: Hassanpour Soroosh , Heppler G. R.
Published: February 2016

The micropolar elasticity theory provides a useful material model for dealing with fibrous, coarse granular, and large molecule materials. Though being a well-known and well-developed elasticity model, the linear theory of micropolar elasticity is not without controversy. Specially simplification of the microppolar elasticity theory to the couple-stress and classical elasticity theories and the required conditions on the material elastic constants for this simplification have not been discussed consistently. In this paper the linear theory of micropolar elasticity is reviewed first. Then the correct approach for a consistent and step-by-step simplification of the micropolar elasticity model with six elastic constants to the couple-stress elasticity model with four elastic constants and the classical elasticity model with two elastic constants is presented. It is shown that the classical elasticity is a special case of the couple-stress theory which itself is a special case of the micropolar elasticity theory.
The Investigation of Stress Distribution on the Tractor Clutch Finger Mechanism by Using Finite Element Method
Authors: Karpat F. , Dogan O. , Yuce C. , Kaya N. , Cengiz G.
Published: February 2016

In recent years, there has been an increasing demand for tractor usage for agricultural activities in the world. Tractors are an integral part of mechanization and have a crucial role to play to enhance agricultural productivity. They are used for many kinds of farm work, under various soil and field conditions. It provides agricultural activities in challenging conditions by using several farming equipment. During the operations, tractors have to efficiently transfer power from the engine to the drive wheels and PTO through a transmission. Tractor clutch is the essential element in this system. During the torque transmission, loads which occur on the clutch components cause damages. In many cases, especially PTO clutch finger mechanism is fractured under the torque transmission.

In this study, finger mechanism, which used in tractor clutch PTO disc, is investigated. Finite element analyses were performed for two different thicknesses (3.5 and 4 mm) of the finger mechanism. Stress and deformation values which occur during the transfer of power in a safe manner are investigated for these thicknesses. The finger mechanism CAD models were created using CATIA V5 and then imported into ANSYS for static finite element analyses. As a result of the analyses, approximately 13% stress decreasing was observed with the increment of the 0.5 mm for the finger thicknesses. Results from the analyses provide an accurate prediction of the material yielding and load path distribution on the PTO clutch finger. To verify the analyses results prototype PTO finger mechanism was manufactured and was conducted bench tests. Consequently, a good correlation was achieved between finite element model and test results.