bluuebunny/crossref_metadata_2025 huggingface dataset:
Global output feedback stabilization for a class of stochastic feedforward nonlinear systems with time-varying input delay
Authors: Ai Weiqing , Zhai Junyong , Fei Shumin
Published: February 2015

This paper investigates the problem of output feedback stabilization for a class of stochastic feedforward nonlinear systems with time-varying input delay. The drift and diffusion terms satisfy the linear growth condition and are dependent on unmeasurable states and the delayed input. First, we use a change of coordinates to introduce a scaling gain into the system. Then, based on the high-gain observer technique, a delay-free output feedback controller with the scaling gain is developed. Based on the Lyapunov–Krasovskii method and the idea of feedback domination, it is shown that the closed-loop system can be rendered globally asymptotically stable in probability via appropriately choosing the scaling gain. Finally, two examples are presented to illustrate the effectiveness of the proposed scheme.
Designing fuzzy logic controller based on combination of terminal sliding mode and state feedback controllers for stabilizing chaotic behaviour in rod-type plasma torch system
Authors: Khari Safa , Rahmani Zahra , Rezaie Behrooz
Published: February 2015

In this paper, a fuzzy logic controller is designed for controlling non-linear behaviours in a rod-type plasma torch system. This system may behave chaotically when its parameters pass through critical values, and gives rise to undesirable oscillations, which degrade the performance of the system. In order to avoid such behaviours, the state feedback controller and the terminal sliding mode controller are combined into a fuzzy system to stabilize the equilibrium point of the system. The fuzzy rules include consequent parts in which state feedback control or terminal sliding mode control is utilized for different conditions. The proposed scheme provides the advantages of both methods, i.e. a decreased settling time is achieved using terminal sliding mode control, and using state feedback control, the chattering phenomenon is removed. The proposed method provides robustness against the external disturbance and uncertainty. Numerical simulations are given to verify that the proposed fuzzy control scheme can effectively control chaotic behaviour of the rod-type plasma torch system and the method provides the best performance among the other methods discussed in the paper.
A case study to examine the imputation of missing data to improve clustering analysis of building electrical demand
Authors: Inman Daniel , Elmore Ryan , Bush Brian
Published: February 2015

Building performance data are widely used for daily operation, improving building efficiency, identifying and diagnosing performance problems, and commissioning. In this study, the authors explore the use of missing data imputation and clustering on an electrical demand dataset. The objective was to compare four approaches of data imputation and clustering analysis. Results of this study suggest that using multiple imputation to fill in missing data prior to performing clustering analysis results in more informative clusters. Commonly used methods to fill in missing data lead to changes in cluster membership that are not suggestive of a change in the building's performance, but instead is a result of the choice of imputation method used.

Practical application: The authors demonstrate, through the use of a case study, the application of a statistically sound method for filling in missing data in large buildings performance datasets. The methods used in this analysis are available through the open-source programming language R and are straight forward to implement. The approach demonstrated in this case study could aid buildings analysts with fault detection and continuous commissioning of large commercial buildings.
Meaning of Illness and Self-Care in Patients With Type 2 Diabetes
Authors: Strom Williams Joni , Walker Rebekah J. , Lynch Cheryl P. , Voronca Delia , Egede Leonard E.
Published: February 2015

Purpose

The purpose of this study was to assess the relationship between meaning of illness, diabetes knowledge, self-care understanding, and behaviors in a group of individuals with type 2 diabetes.

Methods

Patients diagnosed with type 2 diabetes completed questionnaires with measures for diabetes knowledge, self-care understanding, diet adherence, and control problems based on the validated Diabetes Care Profile, as well as a 5-factor Meaning of Illness Questionnaire (MIQ) measure. Linear regression investigated the associations between self-care outcomes and the 5 MIQ factors.

Results

After adjustment for possible confounders, both diabetes self-care understanding and diet adherence were negatively and significantly associated with little effect of illness. Control problems were negatively associated with degree of stress/change in commitments. Diabetes knowledge was not significantly associated with meaning of illness.

Conclusion

Aspects of the meaning attributed to illness were significantly associated with self-care in patients with type 2 diabetes. Therefore, cognitive appraisals may explain variances observed in self-care understanding and behaviors. Based on these results, it is important to understand the negative effect that diabetes could have when promoting self-care understanding and diet adherence. In addition, it shows that helping patients address the stress and changing commitments that result from diabetes may help decrease the amount of diabetes control problems, even if there is little effect on diabetes understanding. Taking these differences into account may help in creating more personalized and effective self-care education plans.
Impact of the Nationwide Intravenous Selenium Product Shortage on the Development of Selenium Deficiency in Infants Dependent on Long‐Term Parenteral Nutrition
Authors: Chen Connie H. , Harris Mary Beth , Partipilo M. Luisa , Welch Kathleen B. , Teitelbaum Daniel H. , Blackmer Allison B.
Published: February 2015

Background: For patients dependent on parenteral nutrition (PN), selenium must be supplemented intravenously. A nationwide intravenous selenium shortage began in April 2011. The impact of this shortage on PN‐dependent infants was evaluated by examining the provision of selenium, development of biochemical deficiency, and costs associated with the shortage. Materials and Methods: This single‐center, retrospective study included PN‐dependent infants aged ≤1 year who weighed ≤30 kg, received PN for ≥1 month, and had ≥1 serum selenium measurement. The primary outcome was the incidence of biochemical selenium deficiency. Secondary outcomes included severity of biochemical deficiency, clinical manifestations, costs, and relationship between serum selenium levels and selenium dose. Results: The average selenium dose decreased 2‐fold during the shortage (2.1 ± 1.2 µg/kg/d; range, 0.2–4.6 µg/kg/d) versus the nonshortage period (3.8 ± 1 µg/kg/d; range, 2.4–6 µg/kg/d; P < .001). A linear relationship between serum selenium concentration and selenium dose was observed (r2 = 0.42), with a dose of 6 µg/kg/d expected to result in normal serum levels in most cases. Similar proportions of patients developed biochemical deficiency in both groups: shortage period, 59.1%; nonshortage, 66.7%; P = .13. The severity of biochemical deficiency was similar between groups. A significant increase in incremental cost during the shortage was observed. Conclusion: This is the first study examining the impact of the intravenous selenium shortage on PN‐dependent infants. Both groups exhibited similarly high incidences of biochemical selenium deficiency, suggesting higher empiric doses may benefit this population. However, ongoing shortages limit the ability to provide supplementation.
Internal Migration, Regional Economic Convergence, and Growth in Croatia
Authors: Borozan Djula
Published: February 2015

The article aims to explore internal migration flows, test for economic convergence, and assess the effects of internal migration (net and gross) on convergence and growth in terms of a neoclassical model in Croatia in the period 2000 to 2011. Croatia is a country with significant and persistent regional economic disparities, migration, and turbulent economic and political changes. The main findings of panel data analysis with fixed effects show that (i) contrary to the expectations based on neoclassical theory, the Croatian counties have been facing absolute and conditional economic divergence; (ii) in- and out-migration works symmetrically; (iii) net migration mainly appears to be a force that accelerates divergence, just opposite to gross in- and out-migration; (iv) although the estimated parameters of net and gross migration have expected signs, their effect size lies in the range from statistically significant but minor to insignificant; and (v) migrant characteristics and behavior matter when the effect size is considered.
Scientific and Regulatory Policy Committee Points-to-consider Paper*
Authors: Engelhardt Jeffery A. , Fant Pierluigi , Guionaud Silvia , Henry Scott P. , Leach Michael W. , Louden Calvert , Scicchitano Marshall S. , Weaver James L. , Zabka Tanja S. , Frazier Kendall S.
Published: February 2015

Drug-induced vascular injury (DIVI) is a recurrent challenge in the development of novel pharmaceutical agents. In recent years, DIVI has been occasionally observed in nonhuman primates given RNA-targeting therapeutics such as antisense oligonucleotide therapies (ASOs) during chronic toxicity studies. While DIVI in laboratory animal species has been well characterized for vasoactive small molecules, and immune-mediated responses against large molecule biotherapeutics have been well described, there is little published information regarding DIVI induced by ASOs to date. Preclinical DIVI findings in monkeys have caused considerable delays in development of promising new ASO therapies, because of the uncertainty about whether DIVI in preclinical studies is predictive of effects in humans, and the lack of robust biomarkers of DIVI. This review of DIVI discusses clinical and microscopic features of vasculitis in monkeys, their pathogenic mechanisms, and points to consider for the toxicologist and pathologist when confronted with ASO-related DIVI. Relevant examples of regulatory feedback are included to provide insight into risk assessment of ASO therapies.
Minimally Invasive Surgery for Osseointegrated Auditory Implants
Authors: Gordon Steven A. , Coelho Daniel H.
Published: February 2015

Objectives

(1) To describe the benefits of the minimally invasive punch technique without soft tissue reduction (PT) for the placement of percutaneous osseointegrated auditory implants. (2) To compare and contrast techniques and outcomes from PT with the linear technique with soft tissue reduction (LT).

Study Design

Case series with chart review

Setting

Performed at a tertiary otology practice at an academic medical center.

Subjects and Methods

LT was used until 2012 when a switch was made for all patients to PT. Preoperative variables recorded included age, sex, BMI, smoking status, indication, device selected, and abutment length. Outcomes measures included surgical time, skin reaction grading by Holgers score at 1 week and at most recent follow‐up, and any other complications. Two‐sample t test and χ2 was used to compare.

Results

A total of 51 patients (34 LT, 17 PT) were identified. Surgical time was found to be significantly shorter for the PT group (LT, 49.2 min; PT, 13.4 min; P <. 001). There were no statistically significant differences between LT and PT for mean Holgers at first (LT, 0.24; PT, 0.47; P =. 87) or final follow‐up (LT, 0.62; PT, 0.41; P =. 22).

Conclusions

The punch technique offers several potential surgical and cosmetic advantages over the linear technique without compromising skin‐reactivity outcomes. This study supports a growing trend toward minimally invasive percutaneous auditory implant surgery.
Effects of Mindfulness Based Stress Reduction Therapy on Subjective Bother and Neural Connectivity in Chronic Tinnitus
Authors: Roland Lauren T. , Lenze Eric J. , Hardin Frances Mei , Kallogjeri Dorina , Nicklaus Joyce , Wineland Andre M. , Fendell Ginny , Peelle Jonathan E. , Piccirillo Jay F.
Published: February 2015

Objective

To evaluate the impact of a Mindfulness Based Stress Reduction (MBSR) program in patients with chronic bothersome tinnitus on the (1) severity of symptoms of tinnitus and (2) functional connectivity in neural attention networks.

Study Design

Open‐label interventional pilot study.

Setting

Outpatient academic medical center.

Subjects

A total of 13 adult participants with a median age of 55 years, suffering from bothersome tinnitus.

Methods

An 8‐week MBSR program was conducted by a trained MBSR instructor. The primary outcome measure was the difference in patient‐reported tinnitus symptoms using the Tinnitus Handicap Index (THI) and Tinnitus Functional Index (TFI) between pre‐intervention, post‐MBSR, and 4‐week post‐MBSR assessments. Secondary outcomes included change in measurements of depression, anxiety, mindfulness, and cognitive abilities. Functional connectivity magnetic resonance imaging (MRI) was performed at pre‐ and post‐MBSR intervention time points to serve as a neuroimaging biomarker of critical cortical networks.

Results

Scores on the THI and TFI showed statistically significant and clinically meaningful improvement over the course of the study with a median ΔTHI of −16 and median ΔTFI of −14.8 between baseline and 4‐week follow‐up scores. Except for depression, there was no significant change in any of the secondary outcome measures. Analysis of the resting state functional connectivity MRI (rs‐fcMRI) data showed increased connectivity in the post‐MBSR group in attention networks but not the default network.

Conclusion

Participation in an MBSR program is associated with decreased severity in tinnitus symptoms and depression and connectivity changes in neural attention networks. MBSR is a promising treatment option for chronic bothersome tinnitus that is both noninvasive and inexpensive.
Grandparents’ and young adult grandchildren’s identity gaps and perceived caregiving intentions
Authors: Pusateri Kimberly B. , Roaché David J. , Kam Jennifer A.
Published: February 2015

Utilizing communication theory of identity, this study examined identity gaps in relation to grandparents’ (GPs') and their young adult grandchildren's (GC's) communication satisfaction and, in turn, perceptions of GC’s caregiving intentions. Actor–partner interdependence models were examined with path analyses, using self-reported, cross-sectional survey data from GPs and GC (200 dyads). In regard to actor effects, as GPs and GC experienced identity gaps, they were less likely to report communication satisfaction. With lower levels of communication satisfaction, GPs were less likely to believe their GC would provide care for them in the future and GC had weaker intentions to provide care in the future. For partner effects, GP identity gaps were indirectly associated with grandchild caregiving intentions through either GP or GC communication satisfaction. By contrast, GC identity gaps were not significantly indirectly associated with GP perceptions of GC caregiving intentions through either GP or GC communication satisfaction.
Ransoming, Compensatory Violence, and Humanitarianism in the Sahel
Authors: Niang Amy
Published: February 2015

Nonstate transnational actors have long played a central role in Sahelian economic structures and geopolitical arrangements because of their capacity to constitute sources of authority and sustenance outside and across state structures. Recently, subversive battalions (qatiba) have resorted to kidnapping, raiding, and ransoming as a means to social justice with a redistributive dimension. Parallels can be drawn with authority structures associated with nineteenth-century privateers and buccaneers, and more recently with pirates operating in the Indian Ocean. The parallel economy of ransoming emerges in a context of critical disruptions of traditional economic and mobility frameworks in the Sahel, the aggressive scramble for resources, and the displacement of the global war on terror in the Sahel. This article examines the legitimation processes used by subversive groups, both ideological and religious; the ethics of ransoming as a form of prosperity endeavor without morality; and an oscillation between cooperation and subversion in the parallel economy of smuggling understood as two aspects of the same strategy of engagement between formal authorities and insubordinate groups in a context of scarcity. It argues that nonconventional forms of ransoming and criminal predation in the Sahel have similarities with practices of states and multinational corporations insofar as these divest ordinary citizens of their ability to become subjects outside the colluding forces of capital, state power, and external interventions.
The road to recovery: Experiences of driving with bipolar disorder
Authors: McNamara Carole , Buckley Sherrie E
Published: February 2015

Introduction

It has been suggested that bipolar disorder impairs cognitive, psychomotor and emotional regulation abilities which could impact an individual’s driving behaviour. This research aimed to investigate experiences of driving with a diagnosis of a bipolar disorder, as a study on this subject has not been located in the literature.

Method

Two focus groups were conducted during a bipolar day programme in an independent psychiatric hospital in the Republic of Ireland ( n = 18). Data was analysed using thematic analysis.

Results

Themes emerging from the data include: the meaning of driving, the impact of bipolar disorder on driving behaviour and the management of driving behaviour when unwell. An unexpected theme was the perceived discriminatory nature of the Irish Road Safety Authority’s fitness to drive guidelines.

Conclusion

Driving is a meaningful activity, enabling engagement in areas of occupation. Participants’ desire to implement their own compensatory strategies when unwell can be viewed as a process of taking control in their recovery and minimising the effects of occupational disruption. Their view that fitness to drive guidelines are inequitable could be related to perceptions that mental illness has a lasting influence on their life narratives.
How is space made in sound? Spatial mediation, critical phenomenology and the political agency of sound
Authors: Revill George
Published: February 2015

This paper examines some of the processes and practices that make sonic spatiality distinctive and sets out theoretical and conceptual resources that might better enable us to understand these processes. It draws on the notion of political agency in order to animate the processual making of sonic space as socio-material relationality. Developing an approach to sonic mediation compatible with a critical phenomenology of the auditory, the paper sets out four interrelated sets of sonic effects central to the making of sonic spaces. It shows how these address a politics of difference which engages affective and representational political processes.
Making Sense of Asian American Ethnic Neighborhoods
Authors: Walton Emily
Published: February 2015

Research on Asian American ethnic neighborhoods lacks appreciation of the national-origin, nativity, and socioeconomic diversity within this racial group. Using the 2000 U.S. Census, this paper creates a novel theoretical typology based on these features of diversity to characterize ethnic neighborhoods ( N = 74) among Chinese, Filipino, Korean, and Vietnamese Americans in California. Korean and Chinese American ethnic neighborhoods are bimodally distributed into immigrant enclaves and resurgent communities. Communities of constraint and immigrant enclaves are overrepresented among Filipino and Vietnamese American ethnic neighborhoods. Linking the neighborhood data with the California Health Interview Survey 2007–2009 ( N = 1,901), I demonstrate that Asian Americans living in resurgent communities have the highest likelihood of reporting good health. Furthermore, ethnic neighborhood type explains some of the differences in health across national-origin groups, indicating that the socioeconomic and nativity resources characterizing ethnic neighborhood environments vary systematically across groups and that this variation matters for important individual outcomes like health.
Aspects of bond behavior for concrete beam strengthened with carbon fibers reinforced polymers–near surface mounted
Authors: Merdas Abdelghani , Fiorio Bruno , Chikh Nasr-Eddine
Published: February 2015

The near surface mounted technique has been used in recent years for the strengthening of reinforced concrete beams. It involves the insertion of strips or rods of carbon fibers reinforced polymers in grooves made previously in the concrete cover of corresponding surfaces, filled with epoxy adhesive for fixation. A parametric study was carried out based on pullout-bending tests in order to evaluate the influence of bond strength, concrete strength, bond length, type and configuration of strengthening on the pullout load, bonding stress, stiffness and failure mode. The influences of these parameters on the bond behavior between the three materials (concrete, epoxy adhesive and carbon fibers reinforced polymer) were evidenced and discussed.
Association of Domestic Violence From Husband and Women Empowerment in Slum Community, Mumbai
Authors: Donta Balaiah , Nair Saritha , Begum Shahina , Prakasam C. P.
Published: February 2015

Prevalence of violence by husband against wife is an indicator of women’s status at household level. The objective of the study is to understand the relationship between domestic violence and women’s empowerment in a slum community in Mumbai, India. Data were collected from a sample of 1,136 married women aged 18 to 39 years having at least one child and reporting of unmet need for family planning. Domestic violence by husband against wife was measured in terms of either physical, sexual, or emotional violence. Three logit regression analyses were carried out using decision-making power, freedom of movement, and justified wife beating as dependent variables separately and socio-demographic and economic variables as independent variables. Furthermore, the relationship between domestic violence and women’s decision-making power, freedom of movement, and justified wife-beating index has been explored. About 21% of women had ever experienced violence, and 38% of women had decision-making power with respect to own health care, household purchase, or visiting family and relatives. A little more than one fifth of the women reported freedom of movement to market, health facilities, or places outside the community. Women who justified wife beating were 2.29 (95% CI [1.59, 3.29]) times at risk of experiencing violence than women who disagreed with the wife-beating statements. Women not empowered in decision making were 1.15 (95% CI [0.91, 1.46]) times at risk of experiencing domestic violence than women who were empowered in decision making. Women who are empowered are less likely to be at risk of domestic violence. Programs aimed at empowering women must address socio-cultural norms relating to justification of violence in marriage.
Public Opinion of the Application of Sex Offender Notification Laws to Female Sex Offenders
Authors: Cain Calli M. , Sample Lisa L. , Anderson Amy L.
Published: February 2015

Sex offender notification laws depend not only on the public’s access of registration information but also on the belief that those on the registry present a danger to society and thus deserve informal monitoring. As registries have expanded to include more people, perhaps citizens feel some people on registry are incapable of committing sex crimes or do not pose a danger to society. A group whose inclusion the public may question is women, as many scholars have argued there is a societal-level denial that females commit sex crimes. Data from the 2012 Nebraska Annual Social Indicators Survey were used to determine whether the public agreed that citizens should be notified of convicted female sex offenders living in their communities, whether they would take preventive action if a female sex offender lived in their neighborhood, and whether they think that female sex crimes are less serious than sex crimes committed by men.
Psychometric Validation of the Compulsive Internet Use Scale
Authors: Dhir Amandeep , Chen Sufen , Nieminen Marko
Published: February 2015

Compulsive Internet usage is on the rise in developing countries such as India. To date, no tested, validated, and verified instrument for measuring compulsive Internet use among Indian adolescents has been made available. In order to bridge this gap, our present study has examined the psychometric properties of the English version of the Compulsive Internet Use Scale (CIUS) with 2,381 adolescent Internet users (aged 12–19) in India. Exploratory and confirmatory factor analyses were conducted to examine the factorial and construct validity, reliability, and homogeneity of the English version of the CIUS. Relationships between adolescents’ CIUS scores, demographics, Information and communication technologies (ICT) accessibility, and problematic ICT use were also examined. The study results confirm that the CIUS has good psychometric properties, high internal reliability, and homogeneity and is a valid self-reporting instrument for measuring compulsive Internet use. The present study reveals the same factor structure as the earlier studies using the CIUS in other languages. Finally, we found that male and older adolescents experience higher compulsive Internet use compared to female and younger adolescents, while compulsive Internet users experience lower life satisfaction, lower academic performance, and problematic ICT use including Internet, mobile, and online gaming.
Solving the Nonresponse Problem With Sample Matching?
Authors: Bethlehem Jelke
Published: February 2015

Over the years, it has become clear that probability sampling is a scientifically sound way to select a sample for a survey. With decreasing response rates, one may wonder, however, to what extent this paradigm still holds. Indeed, due to nonresponse, probability sampling surveys more and more resemble self-selection surveys. Rivers has proposed a different way of data collection based on sample matching. The idea is to select a probability sample from a sampling frame. Selected persons are not asked to complete a questionnaire form, as this would lead to high nonresponse rates. Instead, resembling persons are located in a large (possibly not representative) web panel. These panel members are invited to complete the questionnaire. Their response rate will be high as they agreed to complete survey questionnaires regularly. This article investigates the properties of sample matching in some more detail. Using simulated data, it is explored under which conditions sample matching may work.
Scope and precedent: judicial rule-making under uncertainty
Authors: Clark Tom S
Published: February 2015

I develop a formal model of Supreme Court opinion-writing in an environment of uncertainty. In particular, the model captures how the Supreme Court will optimally design the specificity of its legal rules. The model focuses on the tradeoff between more precise rules which are controlling in a smaller subset of cases against less precise rules, which have wider applicability but yield less certain outcomes. When the basic model is considered in a dynamic world in which the Court is able to hear multiple cases, it yields insights about how the factual representativeness of a case and the clarity of existing precedent jointly affect its optimal opinion-writing and willingness to hear new cases. These last implications provide theoretical foundations for theoretical and empirical questions about rule-making, case selection, and the construction of doctrine.
High dielectric constant composite films with high strength, toughness and thermal stability
Authors: Zhu Shi Sheng , Li Wen Lei , Lin Yu Jin , Zhang Shu Ling
Published: February 2015

The dielectric properties of composite films comprising poly(ether ether ketone) (PEEK) and multiwalled carbon nanotubes (MWCNTs) wrapped in poly(ether sulphone) were investigated. These wrapped-MWCNT–PEEK composite films were fabricated through melt blending and subsequent melt extrusion. At low frequencies, the dielectric constant ( k) of the composite PEEK film with 0.68 vol%-wrapped MWCNTs increased with the frequency, with the value of k being as high as 367 at 103 Hz. The wrapped-MWCNT–PEEK composite films also exhibited superior mechanical and thermal properties. In particular, the tensile strength and elongation at break values of all the composite films were greater than 103 MPa and 170%, respectively, and their 5% weight loss temperatures were higher than 575°C. This was attributable to the high conductivity of the MWCNTs, the uniform dispersion of the wrapped MWCNTs in the PEEK matrix, the strong interfacial adhesion between the wrapped MWCNTs and the PEEK, and the processing method employed, namely, melt extrusion.
Multipart setup planning through integration of process planning and scheduling
Authors: Haddadzade Mohammad , Razfar Mohammad Reza , Zarandi Mohammad Hossein Fazel
Published: February 2015

The importance of integration of process planning and scheduling is evident in today’s competitive manufacturing system. Meanwhile, the setup planning plays an important role for integration, because setup planning is done after process planning, just before scheduling. In this article, a new approach for setup planning for multiparts is introduced to realize integration of process planning and scheduling with more details of manufacturing constraints for setup planning. For this purpose, the necessary and unnecessary (preferred) constraints are defined for setup formation and a new matrix is presented to distinguish these and to specify the precedence of operations. The simulated annealing is used in setup planning for N parts simultaneously based on multi-technical and scheduling objectives. The proposed system is based on the machining operation instead of features, to select machine tools more accurately. Another factor for the selection of machine tools is tolerances that are considered in this article and greatly affected the machining cost. An illustrative example is presented to show the effectiveness of the operation-based system and the second example is presented to demonstrate the influence of multipart setup planning versus single-part setup planning. The results show that considering multiparts improves the scheduling objectives such as makespan.
Numerical and experimental studies of single-stroke bumper forming using high-strength steel and laminate sheets
Authors: Leu Daw-Kwei
Published: February 2015

This work is to assess whether car bumpers can be formed using single-stroke pressing instead of conventional double-stroke pressing. Some basic characteristics of the car bumper forming process are also clarified. An incremental elasto-plastic finite-element method is used to simulate a bumper forming process using high-strength steel and laminate sheets under the plane strain condition. Simulations clearly demonstrate the processes involved in single-stroke forming. A three-layer steel/polymer/steel laminate developed for vibration-damping in an automobile bumper is also tested to demonstrate how shear defects occur between the two skin steel layers along the entire length of the laminate sheet in simulation. The springback phenomenon resulting from the elastic recovery is observed in simulations of the final bumper shape. Accordingly, experiments for high-strength steel sheet were performed to verify the numerical simulation and to investigate how process geometry conditions affect the springback angle, which is an essential consideration when assessing and controlling the final bumper shape in practice. This work improves understanding of the bumper forming processes used in the automotive industry.
Electro-thermal-based finite element simulation and experimental validation of material removal in static gap single-spark die-sinking electro-discharge machining process
Authors: Assarzadeh Saeed , Ghoreishi Majid
Published: February 2015

Existing single spark models are subjected to too simplistic assumptions such as uniform or point heat source, constant plasma radius, invariable materials properties and constant surface temperature during discharge making them far from reality. In this study, more realistic assumptions including Gaussian type distribution of spark heat flux, temperature dependent materials properties, latent heat of melting and expanding plasma channel with pulse current and time have been made to establish a comprehensive modeling platform. The ABAQUS FEM software has been used to simulate the mechanism of crater formation due to a single discharge. The non-uniform thermal flux was programmed through the DFLUX subroutine. The simulation results show that the temperature of work piece decreases as the discharge time increases while the volume of melted and evaporated material increases. A specially designed single spark experimental set-up was developed in laboratory to carry out a few single spark tests for verification purposes. The obtained craters morphologies were examined by optical microscopy and scanning profilometer. It has been shown that the present approach outperforms other previously developed thermal models with respect to cavity outline and size possessing the maximum confirmation errors of 18.1% and 14.1% in predicting crater radius and depth, respectively. Parametric analysis reveals that the melting boundary moves onward by increasing discharge current, whereas it moves back prolonging discharge time. Finally, a closer proximity to experimental material removal rates than those predicted by analytical approach has been recognized which confirms its more precise generalization capabilities towards the real state EDM process.
Methods for quantifying rail seat loads and a review of previous experimentation
Authors: Van Dyk Brandon J , Scheppe Andrew J , Edwards J Riley , Dersch Marcus S , Barkan Christopher PL
Published: February 2015

A railroad sleeper and fastening system is composed of many unique parts that, when assembled, attempt to distribute train wheel loads through the system without damaging the components while providing a safe running surface and track geometry for trains to operate on. In order to evaluate the health of the sleeper and fastening system, there are many areas that need to be examined to ensure that key limit states are not exceeded. One key area of concern is the sleeper rail seat, specifically the load magnitude applied to this surface. There are many different metrics to evaluate the rail seat load, and this report will compare these to determine which should be used given different operating and infrastructure conditions. A sample calculation for each methodology was completed in order to compare how the methods differ, and to more fully understand the strengths and limitations of each methodology. These calculations were completed both with a static load and dynamic load, as the individual approaches account for dynamic loads in a variety of ways. For the purpose of this report, these calculations were completed assuming a concrete sleeper infrastructure. The goal of this paper is to provide an evaluation of the existing rail seat load calculation methodologies to improve current concrete sleeper and fastening system design standards through the application of mechanistic design principles.
Formulae for the intersecting curves of pump-turbine characteristic curves with coordinate planes in three-dimensional parameter space
Authors: Zeng W , Yang JD , Cheng YG , Guo WC
Published: February 2015

Pump-turbine characteristics are important boundary conditions for simulating hydraulic transients in pumped-storage hydroelectric power stations. However, the changing laws of the characteristics of different pump turbines are not well understood. Here, two-dimensional characteristic curves are converted into three-dimensional forms, and the intersecting curves, defined by the intersection of the characteristic curves with the coordinate planes in a parameter space defined by the unit rotational speed, unit discharge, and unit torque, are determined to clarify these changing laws. Basic pump-turbine theory of the flow characteristics and idealizations of the “hump” and “S” regions of the characteristic curves are considered to determine formulae for each intersecting curve. Each formula consists of two unknown coefficients that are obtained from fits to measured data. The dependence of the coefficients on specific speed values is clarified to obtain general formulae governed by specific speed. The nonlinear changing laws of the characteristic curves and their relationship with the flow and operating conditions are analyzed and clarified. This work provides a theoretical basis for predicting the characteristic curves of any pump turbine without model-measured characteristics.
Genetic basis for developmental toxicity due to statin intake using embryonic stem cell differentiation model
Authors: Jyoti S , Tandon S
Published: February 2015

The in utero environment is a key factor controlling the fate of the growing embryo. The deleterious effects of statins during the fetal development are still not very well understood. Data from animal studies and retrospective studies performed in pregnant women give conflicting reports. In this study, using in vitro differentiation model of embryonic stem cells, which mimic the differentiation process of the embryo, we have systematically exposed the cells to lipophilic statins, simvastatin, and atorvastatin at various doses and at critical times during differentiation. The analysis of key genes controlling the differentiation into ecto-, meso- and endodermal lineages was assessed by quantitative polymerase chain reaction. Our results show that genes of the mesodermal lineage were most sensitive to statins, leading to changes in the transcript levels of brachyury, Flk-1, Nkx2.5, and α/β-myosin heavy chain. In addition, changes to endodermal marker α-fetoprotein, along with ectodermal Nes and Neurofilament 200 kDa, imply that during early differentiation exposure to these drugs leads to altered signaling, which could translate to the congenital abnormalities seen in the heart and limbs.
Finite element analysis on active vibration control using lead zirconate titanate–Pt–based functionally graded piezoelectric material
Authors: Sharma Anshul , Kumar Anuruddh , Kumar Rajeev , Vaish Rahul , Chauhan Vishal S
Published: February 2015

The numerical simulations for active vibration control of the host structure using lead zirconate titanate–Pt-based functionally graded piezoelectric material are presented in this article. The material properties (both mechanical and electrical) of the lead zirconate titanate–Pt-based functionally graded piezoelectric material are graded in the thickness direction according to the volume fraction power law distribution. The finite element modeling using first-order shear deformation theory is implemented to predict static and dynamic responses of the vibrating structure. A constant negative velocity feedback controller is designed to provide closed-loop feedback control. Both static and dynamic controls of the host structure are numerically simulated to demonstrate the effectiveness of the proposed lead zirconate titanate–Pt-based functionally graded piezoelectric material. The numerical results show significant variation in sensing and actuating capability up to a certain volume fraction index ( n).
How Men Manage Bulbar Urethral Stricture by Concealing Urinary Symptoms
Authors: Whybrow Paul , Rapley Tim , Pickard Robert , Hrisos Susan
Published: February 2015

In this article, we present findings from research conducted as part of a multi-center surgical trial. Bulbar urethral stricture, a narrowing of the middle urethra, is a common cause of urinary problems in men that can have a profound impact on their lives. Semi-structured interviews were conducted with a sample of 19 men seeking treatment for urethral stricture. The findings reveal how men tend to develop routines and tactics to adapt to their symptoms and hide them from others rather than seek help. We argue that this concealment becomes an inseparable part of how the disease is managed and is an additional hidden practical and emotional burden for these men. In addition, we suggest that the patients only sought curative treatments once practices of social concealment are no longer viable.
Leadership, Innovation, and Strategic Change
Authors: Seong Sorah , Kim Yeongsu , Szulanski Gabriel
Published: February 2015

Continuing the emerging tradition of the Knowledge and Innovation (K&I) Interest Group at the Strategic Management Society (SMS) Conference to interview foundational scholars in strategic management, we invited Professor Michael Tushman from Harvard Business School (HBS) as our guest of honor this year. The interview provided a rare opportunity to get behind the scenes of the author’s much celebrated scholarly contribution to the field as well as his responses to some of the new findings within and across his work over time.
A damage model for fracking
Authors: Norris J Quinn , Turcotte Donald L , Rundle John B
Published: February 2015

Injections of large volumes of water into tight shale reservoirs allow the extraction of oil and gas not previously accessible. This large volume “super” fracking induces damage that allows the oil and/or gas to flow to an extraction well. The purpose of this paper is to provide a model for understanding super fracking. We assume that water is injected from a small spherical cavity into a homogeneous elastic medium. The high pressure of the injected water generates hoop stresses that reactivate natural fractures in the tight shales. These fractures migrate outward as water is added creating a spherical shell of damaged rock. The porosity associated with these fractures is equal to the water volume injected. We obtain an analytic expression for this volume. We apply our model to a typical tight shale reservoir and show that the predicted water volumes are in good agreement with the volumes used in super fracking.
Plantar Loading Forces While Walking in a Below-Knee Cast With an Attached Loadbearing Frame
Authors: Berwin James Theo , Burton Thomas Michael Weston , Taylor Jonathan , McGregor Alison H. , Roche Andy
Published: February 2015

Background:

We measured loading forces across different points of the plantar foot surface to examine how different types of casts affect load distribution through the foot and ankle. The patella tendon-bearing (PTB) or Sarmiento cast is the current “gold-standard” casting method for offloading force through the foot and ankle. We aimed to determine if a rocker bottom frame attached to a below-knee cast (Beagle Böhler Walker) would be as effective or better at reducing load distribution during full weightbearing.

Method:

We applied TekScan FlexiForce A201 force sensors to the first and fifth metatarsal heads and the plantar surface of the calcaneus of 14 healthy volunteers. All volunteers had force measurements taken without a cast applied and then with a traditional Sarmiento cast, a standard below-knee cast, and a below-knee cast with the Böhler Walker frame fitted.

Results:

Compared with a standard below-knee cast, the Böhler Walker frame reduced the mean peak force through the head of the first metatarsal by 58.9% ( P < .0001), 73.1% through the head of the fifth metatarsal ( P < .0001), and 32.2% ( P < .0001) through the calcaneus. The Sarmiento cast demonstrated a mean percentage reduction in peak force of 8.6% ( P = .39) and 4.4% ( P = .87) through the first and fifth metatarsal heads, respectively, but increased the mean peak force by 5.9% ( P = .54) through the calcaneus.

Conclusion:

Using a Böhler Walker frame applied to a below-knee cast significantly reduced weight transfer through the foot compared with a Sarmiento cast or standard below-knee cast.

Clinical Relevance:

This reduction in force through the foot could mean early weightbearing would be safer in patients with a wide variety of foot and ankle pathologies such as ankle fractures or operative fixations. This may reduce the incidence of immobility-dependent morbidity.
Multi-modal vibration control of truss bridges with tuned mass dampers under general loading
Authors: Debnath Nirmalendu , Deb SK , Dutta Anjan
Published: February 2015

Applications of tuned mass damper (TMD) systems for bridge structures are observed for mitigation of problem related to excessive vibration induced by either wind loading or vehicle loading, where dominant modes usually in one direction (commonly vertical) are taken into account. Considering modes dominant in one direction may not be considered as a robust practice while any bridge structure is having dominant modes along both the transverse and vertical directions and the same bridge structure is subjected to loading along both the directions. In the present study, an approach for simultaneous control of major horizontal, vertical and torsional modes is presented targeting robust vibration control under general loading condition. A strategy using modal frequency response function (FRF) is proposed based on the traditional mode-wise control approach. The proposed modal FRF based approach is applied to an existing important large truss bridge (Saraighat Bridge) to carry out an analytical design of TMD system considering general loading conditions. The designed TMD system is found to demonstrate good performance under various white-noise based general loading conditions.
Fractional complex-order model for HIV infection with drug resistance during therapy
Authors: Pinto Carla MA , Carvalho Ana RM
Published: February 2015

We propose a fractional complex-order model for drug resistance in HIV infection. We consider three distinct growth rates for the CD4+ T helper cells. We simulate the model for different values of the fractional derivative of complex order Dα±jβ, where α,β ∈  R+, and for distinct growth rates. The fractional derivative of complex order is a generalization of the integer-order derivative where α = 1 and β = 0. The fractional complex-order system reveals rich dynamics and variation of the value of the complex-order derivative sheds new light on the modeling of the intracellular delay. Additionally, fractional patterns are characterized by time responses with faster transients and slower evolutions towards the steady state.
A Framework for Integrating Water Projects in Disaster Reconstruction Processes in the International Context
Authors: Juran Luke
Published: February 2015

Water projects triggered by disaster reconstruction processes are inherently unique and warrant a specialized approach. Thus, the objective of this article is to guide reconstruction actors toward the establishment of more culturally and environmentally sensitive water arrangements by providing a framework of key points to consider. Water infrastructure introduced after disasters differs from “normal” water infrastructure in several distinct ways: nature and needs of the subjects, expectations of recovery and rehabilitation, scale, funding and organizational structure, resettlement, and temporal constraints. Acknowledging these differences, a framework is presented to more aptly manage water sector reconstruction. The framework—informed by fieldwork in post-tsunami South India, the literature, and gaps therein—seeks to minimize project failures that have surfaced across space, time, and disaster.