bluuebunny/crossref_metadata_2025 huggingface dataset:
Young people at risk of psychosis: Their subjective experiences of monitoring and cognitive behaviour therapy in the early detection and intervention evaluation 2 trial
Authors: Byrne Rory E. , Morrison Anthony P.
Published: August 2013

Objectives

To explore participants' experiences of ‘enhanced monitoring’ and cognitive behaviour therapy (CBT) within a randomized controlled trial evaluating early detection and prevention of psychosis (‘early detection and intervention evaluation [EDIE] 2’).

Design

Semi‐structured qualitative interviews were conducted with a sample of participants at the end of their involvement with the trial.

Methods

Ten young people were interviewed; six males and four females, with a mean age of 27.5. Nine participants identified themselves as White British and one Black British. All participants had received ‘enhanced monitoring’ during the trial, and 8 of 10 also received CBT. Interviews were transcribed verbatim and analysed using thematic analysis to identify central themes within and among participants' accounts.

Results

Three super‐ordinate thematic areas were identified: ‘a chance to talk’, monitoring‐specific themes, and CBT‐specific themes. The central theme (‘a chance to talk’) was drawn from across all participants' accounts and represents the most consistently valued attribute of participants' experiences of the EDIE 2 trial. Sub‐themes of this topic were identified as follows: interpersonal engagement, informality and normalization, and ‘opening up’. Sub‐themes related to monitoring include the following: clarity and reassurance, ‘a therapeutic process’, and challenges. CBT experience was most consistently conceptualized as ‘rethinking things’, and two additional CBT‐specific sub‐themes were identified: hard work and moving forward.

Conclusions

Our findings suggest that for young people at risk of psychosis, a normalizing psychosocially oriented assessment and monitoring process may have benefits for many, while CBT may help to reduce the negative impact of unusual psychological experiences for both the short‐ and long term.

Practitioner points

Young people considered at risk of psychosis highly value normalizing, collaborative, and flexible approaches when engaging with research or clinical staff.

All of our participants highlighted the primary value of their engagement with staff members as having a ‘chance to talk’ about their experiences and difficulties.

CBT seems to be widely acceptable among ‘at‐risk’ participants, though further research is required to establish the ‘key ingredients’ of effective CBT for ‘at‐risk’ individuals.

Valued CBT‐related outcomes highlighted by participants included improved psychosocial understanding of their difficulties, improved coping ability, and greater optimism for the future.
Antibiotic Sensitivity and Resistance Patterns in Pediatric Staphylococcal Scalded Skin Syndrome
Authors: Braunstein Inbal , Wanat Karolyn A. , Abuabara Katrina , McGowan Karin L. , Yan Albert C. , Treat James R.
Published: August 2013

Historical resistance patterns often guide empiric antibiotic choices in staphylococcal scalded skin syndrome (SSSS), but little is known about the difference in susceptibility between SSSS and other childhood staphylococcal infections. A retrospective chart review of culture‐confirmed cases of SSSS seen in the inpatient dermatology consultation service at the Children's Hospital of Philadelphia between 2005 and 2011 was performed. Most cases of SSSS at our institution are due to oxacillin‐susceptible Staphylococcus aureus, and approximately half of the cases are due to clindamycin‐resistant strains. Clindamycin and a penicillinase‐resistant penicillin are suggested as empiric treatment for SSSS until culture susceptibility data are available to guide therapy.
Friendship characteristics, psychosocial development, and adolescent identity formation
Authors: JONES RANDALL M. , VATERLAUS JOHN M. , JACKSON MARK A. , MORRILL TORREY B.
Published: August 2013

Young adults (n = 702; 18–23 years old) completed measures of psychosocial development, identity status, and friendship. Friendship conflict and support were related with psychosocial development, and with the identity statuses. As per Erikson's prescription, early psychosocial stages were relevant to the identity statuses. After statistically controlling for the predictive variability contributed by trust, autonomy, initiative, and industry with the identity status measures, conflict and support within friendships contributed predictive variability to identity achievement (3.2%), moratorium (2.4%), and diffusion (2.5%), but neither conflict nor support within friendships was related to foreclosure scores. Conflict within friendships was positively related with moratorium and diffusion, and support within friendships was negatively related with diffusion.
“Tell me I'm sexy . . . and otherwise valuable”: Body valuation and relationship satisfaction
Authors: MELTZER ANDREA L. , McNULTY JAMES K.
Published: August 2013

Although extant research demonstrates that body valuation by strangers has negative implications for women, Studies 1 and 2 demonstrate that body valuation by a committed male partner is positively associated with women's relationship satisfaction when that partner also values them for their nonphysical qualities, but negatively associated with women's relationship satisfaction when that partner is not committed or does not value them for their nonphysical qualities. Study 3 demonstrates that body valuation by a committed female partner is negatively associated with men's relationship satisfaction when that partner does not also value them for their nonphysical qualities but unassociated with men's satisfaction otherwise. These findings join others demonstrating that fully understanding the implications of interpersonal processes requires considering the interpersonal context.
Individual and organisational factors influencing registered nurses’ attitudes towards patient advocacy in Swedish community health care of elders
Authors: Josse‐Eklund Anna , Wilde‐Larsson Bodil , Petzäll Kerstin , Sandin‐Bojö Ann‐Kristin
Published: August 2013

Aim

The aim of this study was to describe and explore individual and organisational factors potentially influencing registered nurses’ (RNs) attitudes towards patient advocacy.

Methods and Sample

In a quantitative cross‐sectional study, data were collected from 226 RNs in community health care of elders. A questionnaire was used to measure a number of factors including attitudes towards patient advocacy, nursing competence, personality traits, individual preferences regarding the quality of health care and working climate. A multiple regression analysis was performed.

Results

The results showed that individual factors of nursing competence and individual preferences of the quality of health care, as well as organisational factors of the working climate, explained 26.2% of the variance in the RNs’ attitudes towards patient advocacy.

Conclusions

Although the mentioned individual factors may be intertwined, the conclusion is that both individual and organisational factors influenced RNs’ attitudes towards patient advocacy. The results do not verify that nursing experience, workplace experience, educational level or personality traits influence the RNs’ attitudes towards patient advocacy. The proportion of explained variance indicates that additional factors also influence attitudes towards patient advocacy, and more research is needed to shed further light on these factors.
“Is This Something You Want?”: Genetic Counselors’ Accounts of Their Role in Prenatal Decision Making
Authors: Markens Susan
Published: August 2013

With the widespread availability of prenatal genetic diagnosis, bioethical concerns have emerged about why women make use of these technologies, and the potential eugenic implications. Research on women's experience with genetic screening often suggests that genetic counselors encourage women to undergo prenatal testing and to terminate pregnancies with abnormalities. Yet, this key professional remains relatively understudied. To fill this lacuna, this article examines genetic counselors’ accounts of their role in the decision‐making process, drawing on 26 qualitative interviews with master's‐trained genetic counselors and illustrative observations of a prenatal counselor. In the context of debates about reproductive politics and genomic medicine, I identify the ways in which genetic counselors view their work and position themselves. I find that contrary to assumptions, genetic counselors provide accounts of being just as likely to discourage as to encourage invasive testing, and persuade against instead of promote termination of affected pregnancies. These findings suggest that genetic counselors may play a more nuanced and less coercive role than their critics contend, challenge assumptions about genetic counselors’ roles in prenatal genetic testing uptake and abortion, and shed light on how this specific professional may curb rather than promote eugenic tendencies feared with the normalization of prenatal screening.
The phylogeny of the superfamily Coccoidea (Hemiptera: Sternorrhyncha) based on the morphology of extant and extinct macropterous males
Authors: HODGSON CHRIS J. , HARDY NATE B.
Published: August 2013

Currently, 49 families of scale insects are recognised, 33 of which are extant. Despite more than a decade of DNA sequence‐based phylogenetic studies of scales insects, little is known with confidence about relationships among scale insects families. Multiple lines of evidence support the monophyly of a group of 18 scale insect families informally referred to as the neococcoids. Among neococcoid families, published DNA sequence‐based estimates have supported Eriococcidae paraphyly with respect to Beesoniidae, Dactylopiidae, and Stictococcidae. No other neococcoid interfamily relationship has been strongly supported in a published study that includes exemplars of more than ten families. Likewise, no well‐supported relationships among the 15 extant scale insect families that are not neococcoids (usually referred to as ‘archaeococcoids’) have been published. We use a Bayesian approach to estimate the scale insect phylogeny from 162 adult male morphological characters, scored from 269 extant and 29 fossil species representing 43/49 families. The result is the most taxonomically comprehensive, most resolved and best supported estimate of phylogenetic relationships among scale insect families to date. Notable results include strong support for (i) Ortheziidae sister to Matsucoccidae, (ii) a clade comprising all scale insects except for Margarodidae s.s., Ortheziidae and Matsucoccidae, (iii) Coelostomidiidae paraphyletic with respect to Monophlebidae, (iv) Eriococcidae paraphyletic with respect to Stictococcidae and Beesoniidae, and (v) Aclerdidae sister to Coccidae. We recover strong support for a clade comprising Phenacoleachiidae, Pityococcidae, Putoidae, Steingeliidae and the neococcoids, along with a sister relationship between this clade and Coelostomidiidae + Monophlebidae. In addition, we recover strong support for Pityococcidae + Steingeliidae as sister to the neococcoids. Data from fossils were incomplete, and the inclusion of extinct taxa in the data matrix reduced support and phylogenetic structure. Nonetheless, these fossil data will be invaluable in DNA sequence‐based and total evidence estimates of phylogenetic divergence times.
Genetic polymorphism of KIR2DL4 (CD158d), a putative NK cell receptor for HLA‐G, does not influence susceptibility to asthma
Authors: Le Page M. E. L. , Goodridge J. P. , Zhang G. , Holt P. G. , Sly P. , Witt C. S.
Published: August 2013

Human leukocyte antigen (HLA)‐G is upregulated on the bronchial epithelium of asthma patients and genetic polymorphism affecting expression of HLA‐G has been reported to influence susceptibility to asthma. As the NK cell receptor KIR2DL4 has been reported to induce interferon gamma (IFNγ) secretion when ligated with HLA‐G, we postulated that the 9A/10A genetic polymorphism of KIR2DL4 which influences receptor structure may influence susceptibility to asthma. KIR2DL4 genotypes were determined in two cohorts of children (n = 219 and n = 1356) in whom total serum IgE, allergen‐specific IgE, atopy, bronchial reactivity and asthma symptoms had been studied between birth and 14 years. No reproducible associations with KIR2DL4 genotype were identified, leading us to conclude that the KIR2DL4 9A/10A polymorphism has no influence on susceptibility to asthma.
Sequencing of a novel HLA‐B allele, B*51:153, in a Spanish individual
Authors: Planelles D. , Balas A. , Sanz G. F. , Rodríguez‐Cebriá M. , Vicario J. L.
Published: August 2013

HLA‐B*51:153 shows two nucleotide differences compared with B*51:08 at codon 163 (CTG>ACG), resulting in one amino acid replacement, 163L>163T.
Maternal mortality, birth with a health professional and distance to obstetric care in Indonesia and Bangladesh
Authors: Scott S. , Chowdhury M. E. , Pambudi E. S. , Qomariyah S. N. , Ronsmans C.
Published: August 2013

Objective

To examine the relationship between distance to a health facility, consulting a health professional and maternal mortality.

Methods

Retrospective cohort study in Matlab, Bangladesh (1987–2005), to collect data on all pregnancies, births and deaths. In Java, Indonesia (2004–2005), an informant‐based approach indentified maternal deaths and a population‐based survey sampled women who survived birth. Logistic regression was used to examine the influence of distance to a health facility and uptake of a health professional on odds of dying.

Results

Maternal mortality was 320 per 100 000 births (95% CI: 290, 353) in Indonesia and 318 per 100 000 (95% CI: 272, 369) in Bangladesh. Women who lived further from health centres in both countries were less likely to have their births attended by health professionals than those who lived closer. For women who were assisted by a health professional, the odds of dying increased with increasing distance from a health centre [odds ratio per km; Indonesia: 1.07 (95% CI: 1.02–1.11), Bangladesh: 1.47 (95% CI: 1.22–1.78)]. There was no evidence for an association between distance to a health centre and maternal death for women who were not assisted by a health professional.

Conclusions

Even in settings where health services are relatively close to women's homes, distance to a health facility affects maternal mortality for women giving birth with a health professional. Women may only seek professional care in an emergency and may be unable to reach timely care when living far away from a health centre.
Cytomegalovirus (CMV) seroprevalence in Japanese blood donors and high detection frequency of CMV DNA in elderly donors
Authors: Furui Yasumi , Satake Masahiro , Hoshi Yuji , Uchida Shigeharu , Suzuki Ko , Tadokoro Kenji
Published: August 2013

Background

The current prevalence of cytomegalovirus (CMV) in Japan and the risk of CMV transfusion transmission are unknown in the era of seronegative leukoreduced blood components.

Study Design and Methods

We measured CMV‐specific immunoglobulin (Ig)M and IgG in 2400 samples of whole blood collected from 12 groups of blood donors categorized by sex and age at 10‐year intervals from their teens to their 60s. We also tested for CMV DNA using polymerase chain reaction in the cellular fractions of all samples.

Results

We found that 76.6% of blood donors were CMV seropositive. The seroprevalences among donors in their 20s and 30s were 58.3 and 73.3%, respectively. We detected CMV DNA in the cellular fraction of 4.3% of samples from donors in their 60s and in 1.0% of samples from donors younger than 60 years. None of the 562 seronegative samples was DNA positive. Furthermore, 14% of DNA‐positive samples also contained DNA in the plasma fraction, and two of five such samples were derived from donors in their 60s. Leukoreduced plasma components derived from donations with CMV DNA in plasma samples also contained a relevant amount of CMV DNA.

Conclusion

The seroprevalence of CMV among Japanese blood donors of child‐bearing age has not changed over the past 15 years. Latent CMV becomes reactivated more frequently among elderly donors than among younger donors. A proportion of them have free CMV DNA in their plasma fraction, which could not be diminished by leukoreduction. The risk of transfusion‐transmitted CMV infection in blood with plasma CMV DNA should be determined.
MAGNETIC RESONANCE IMAGING OF PRIMARY AND CONCOMITANT FLEXOR ENTHESOPATHY IN THE CANINE ELBOW
Authors: de Bakker Evelien , Gielen Ingrid , Kromhout Kaatje , van Bree Henri , Van Ryssen Bernadette
Published: August 2013

Flexor enthesopathy is a recently recognized elbow disorder in dogs and considered to be an important differential diagnosis for elbow lameness. Primary and concomitant forms of the disease have been previously described and treatments differ for the two forms. The goal of this prospective study was to compare magnetic resonance imaging (MRI) findings for dogs with primary flexor enthesopathy (n = 17), concomitant flexor enthesopathy (n = 23), elbow dysplasia alone (n = 13), and normal elbows (n = 7). Each elbow joint underwent MRI using the same low‐field scanner. Sequences included transverse and sagittalT1‐weighted (before and after IV contrast), transverse and sagittal T2‐weighted, and dorsal STIR. For each elbow,MRIlesions were recorded based on a consensus of two observers unaware of group status. Magnetic resonance imaging lesions involving flexor tendons were found in 100% of clinically affected joints with primary flexor enthesopathy and 96% of clinically affected joints with concomitant flexor enthesopathy. Thickened flexor muscles were the most common lesions, followed by hyperintense tendon signal and contrast enhancement. Irregular, thickened medial humeral epicondyle, edema, and calcified body lesions were less frequently observed. Magnetic resonance imaging characteristics of flexor enthesopathy were not found in normal joints or those affected by elbow dysplasia alone. No significant differences in frequencies and details of individualMRIcharacteristics were found between primary and concomitant flexor enthesopathy groups. Findings indicated that MRI is a sensitive technique for detection of flexor enthesopathy lesions in dogs, however, MRI characteristics do not allow differentiation of primary versus concomitant forms of the disease.
COMPUTED TOMOGRAPHY OF CANINE ELBOW JOINTS AFFECTED BY PRIMARY AND CONCOMITANT FLEXOR ENTHESOPATHY
Authors: de Bakker Evelien , Gielen Ingrid , van Caelenberg Annemie , van Bree Henri , van Ryssen Bernadette
Published: August 2013

Flexor enthesopathy is an important differential diagnosis for elbow lameness in dogs. The disorder can be a primary cause of elbow lameness or concomitant with other elbow pathology. Since treatment differs for primary and concomitant forms of flexor enthesopathy, a noninvasive method for distinguishing between them is needed. In the current prospective study, computed tomographic (CT) examination was performed before and after IV injection of contrast in 17 dogs with primary flexor enthesopathy, 24 dogs with concomitant flexor enthesopathy, 13 dogs with elbow dysplasia, and seven normal dogs. Dogs were assigned to groups based on results of clinical examination and at least three other imaging modalities. Computed tomographic lesions consistent with flexor enthesopathy were found in all clinically affected joints with primary flexor enthesopathy and in 29 of the 30 clinically affected joints with concomitant flexor enthesopathy. Those lesions were not found in sound elbows or joints affected by elbow dysplasia. Flexor lesions detected in dogs with primary flexor enthesopathy were not significantly different from those detected in dogs with the concomitant form. Findings indicated that CT can be applied to detect flexor enthesopathy, but a distinction between the primary and concomitant forms was not always possible. Authors recommend the use of multiple diagnostic techniques for treatment planning in affected dogs.
GLOBAL BIOETHICS: TRANSNATIONAL EXPERIENCES AND ISLAMIC BIOETHICS
Authors: ten Have Henk
Published: August 2013

In the 1970s “bioethics” emerged as a new interdisciplinary discourse on medicine, health care, and medical technologies, primarily in Western, developed countries. The main focus was on how individual patients could be empowered to cope with the challenges of science and technology. Since the 1990s, the main source of bioethical problems is the process of globalization, particularly neo‐liberal market ideology. Faced with new challenges such as poverty, inequality, environmental degradation, hunger, pandemics, and organ trafficking the bioethical discourse of empowering individuals is no longer sufficient. Global bioethics nowadays is concerned with applying and implementing a universal ethical framework. Islamic bioethics has contributed to creating such framework (exemplified in the UNESCO Universal Declaration on Bioethics and Human Rights) while at the same time it is continuously articulating and interpreting this framework in specific settings and contexts.
INDIVIDUALITY IN THEOLOGICAL ANTHROPOLOGY AND THEORIES OF EMBODIED COGNITION
Authors: Turner Léon
Published: August 2013

Contemporary theological anthropology is now almost united in its opposition toward concepts of the abstract individual. Instead there is a strong preference for concrete concepts, which locate individual human being in historically and socioculturally contingent contexts. In this paper I identify, and discuss in detail, three key themes that structure recent theological opposition to abstract concepts of the individual: (1) the idea that individual human beings areconstitutedin part by their relations with their environments, with other human beings, and with God; (2) the idea that individual human beings are unique entities; (3) the idea that individual human beings cannot be conceptualized in atemporal terms. Subsequently, I seek to demonstrate that theories of embodied cognition offer broad, if not unconditional, support for the concept of the concrete individual. As such, I suggest, theories of embodied cognition provide a valuable resource for dialogue between contemporary science and theological anthropology.
A Unified Approach to H∞ Control of Singular Markovian Jump Systems
Authors: Wang Guoliang , Li Hongyi
Published: August 2013

This paper considers the H∞ control problem for a class of singular Markovian jump systems (SMJSs), where the jumping signal is not always available. The main contribution of this paper introduces a new approach to a mode-independent (MI) H∞ controller by exploiting the nonfragile method. Based on the given method, a unified control approach establishing a direct connection between mode-dependent (MD) and mode-independent controllers is presented, where both existence conditions are given in terms of linear matrix inequalities. Moreover, another three cases of transition probability rate matrix (TRPM) with elementwise bounded uncertainties, being partially unknown and to be designed are analyzed, respectively. Numerical examples are used to demonstrate the effectiveness of the proposed methods.
Simulation and Experimentation of a Precise Nonlinear Tracking Control Algorithm for a Rotary Servo-Hydraulic System With Minimum Sensors
Authors: Toufighi M. H. , Sadati S. H. , Najafi F. , Jafari A. A.
Published: August 2013

The dynamics of hydraulic systems involves slow and fast modes. These modes are associated with the mechanical components and those involving fluid flow, respectively. As such, controllers for electro-hydraulic servo systems (EHSS) can be designed and analyzed using singular perturbation theory. In this paper, a singular perturbation control (SPC) algorithm is proposed and investigated on a rotary EHSS modeled based on a two-time-scale behavior of the system. For modeling, the components of the hydraulic system, specifically the nonlinear model of the orifice in servo valve, are modeled. A mathematical modeling and nonlinear control analysis that validated by experiment is presented. The controlled system with the SPC algorithm tracks a fairly smooth trajectory with very small error. As well, the control algorithm is successfully verified by experiment as the main contribution of the paper. In addition, this is robust to variations in the hydraulic fluid bulk modulus such that only its nominal value is sufficient. Furthermore, the proposed control design will not require derivatives of the control pressures and any output acceleration feedback. Hence, it can be implemented easier in the real system setup. The controller design approach addresses the nonlinearities of the rotary EHSS. The parameters of the real system model are experimentally identified using the continuous recursive least square method.
Model-Based Condition Monitoring of an Electro-Hydraulic Valve
Authors: Steinboeck Andreas , Kemmetmüller Wolfgang , Lassl Christoph , Kugi Andreas
Published: August 2013

In many hydraulic systems, it is difficult for human operators to detect faults or to monitor the condition of valves. Based on dynamical models of an electro-hydraulic servo valve and a hydraulic positioning unit, we develop a parametric fault detection and condition monitoring system for the valve. Our approach exploits the nexus between the spool position, the geometric orifice area, the flow conditions at wearing control edges, and the velocity of the controlled cylinder. The effective orifice area of each control edge is estimated based on measurement data and described by aggregate wear parameters. Their development is monitored during the service life of the valve, which allows consistent tracking of the condition of the valve. The method is suitable for permanent in situ condition monitoring. Flow measurements are not required. Computer simulations and measurement results from an industrial plant demonstrate the feasibility of the method.
Modeling and Analysis of Fuel Injection Split for Diesel Engine Active Fueling Control
Authors: Yan Fengjun , Chen Song , Zeng Xiangrui , Zhao Junfeng , Wang Junmin
Published: August 2013

With the improvements in Diesel engine injection systems, the fueling-path, which is more accurate, flexible, and faster than the air-path, can be actively utilized in conventional and advanced combustion mode controls, especially for enhancing the combustion transient performance. In this paper, fuel injection split models are proposed to describe the relationship between fuel split ratio and two combustion outputs, i.e., the crank angle at 50% heat released (CA50) and the indicated mean effective pressure (IMEP). The model parameters are related to the engine in-cylinder thermal boundary conditions, referred to as the in-cylinder conditions (ICCs). The models were verified by engine experimental data with identical and different ICCs under different engine operating conditions. Such models can be potentially utilized in active fueling control for Diesel engine combustion control, and therefore benefit engine fuel efficiency and reduce engine-out emissions.
Robust H∞ Control of Hysteresis in a Piezoelectric Stack Actuator1
Authors: Chuang Ning , Petersen Ian R.
Published: August 2013

This paper describes an H∞ control method for controlling hysteresis in a piezoelectric stack actuator. The actuator used is a high-performance monolithic multilayer piezoelectric stack actuator. The proposed control method involves the use of a capacitor in series with the piezoelectric actuator to provide a measured output voltage which is proportional to the charge on the piezoelectric actuator. The controller is designed based on a model of the hysteresis nonlinearity constructed using experimental data. The parameters in the nonlinear model of the system are obtained from the measurements on the piezoelectric actuator circuit. Our focus in this paper is to develop a tracking controller based on a charge output of the piezoelectric actuator system and to reduce the hysteresis nonlinearity. The paper considers a robust H∞ tracking controller to control the piezoelectric actuator based on an uncertain system model. Experimental results show that the hysteresis can be significantly reduced and the measured output can closely track a 5 Hz sawtooth reference input signal when the H∞ controller is used.
String Exponential Stability With Mode Constraint of Stochastic Vehicle Following Systems
Authors: Xu Xiaohui , Zhang Jiye , Tang Lan
Published: August 2013

Associated with automatic vehicle following system is the problem of the stability of a platoon of vehicles. The stability with mode constraint is the property of damping disturbances as they travel away from the source in the system. In this paper, a class of infinite-dimensional vehicle longitudinal following system with stochastic disturbance is analyzed. By applying geometrical analysis method, a lemma for analyzing the stability of generalized vector comparison inequalities with respect to the original systems is established. With the help of the lemma, some sufficient conditions for assuring the string exponential stability with mode constraint of the original system are obtained by applying vector Lyapunov function method. The obtained conditions are less conservative than the existing ones. A numerical example is given to show the effectiveness of the established conditions.
Adaptive Control With Internal Model for High-Performance Precision Motion Control and Its Application to a Fast-Acting Piezoelectric Actuator
Authors: Lin Chi-Ying , Tsao Tsu-Chin
Published: August 2013

This paper proposes an adaptive control scheme that minimizes the least-mean-square (LMS) value of the plant output while meeting the constraints of canceling deterministic exogenous signals generated by a priori dynamics. This scheme may be applied to a broad range of applications in which the exogenous input signals to the plant contain both deterministic and stochastic components. The adaptive control includes both feedback and previewed feedforward actions. In both actions, the deterministic signal model is included as a constraint of the dynamics from the external input to the plant output by determining solutions for a Bezout identity. The proposed scheme is applied to a fast-acting piezoelectric actuator (PZT) to generate precise dynamic motion profiles. This paper presents the experimental results to demonstrate the effectiveness of the proposed adaptive control scheme.
Velocity and Force Observers for the Control of Robot Manipulators
Authors: Arteaga–Pérez Marco A. , Rivera–Dueñas Juan C. , Gutiérrez–Giles Alejandro
Published: August 2013

In this paper, position/force tracking control for rigid robot manipulators interacting with its environment is considered. It is assumed that only joint angles are available for feedback, so that velocity and force observers are designed. The principle of orthogonalization is employed for this particular purpose and some of its main properties are fully exploited to guarantee local asymptotical stability. Only the force observer requires the dynamic model of the robot manipulator for implementation, and the scheme is developed directly in workspace coordinates, so that no inverse kinematics is required. The proposed approach is tested experimentally and compared with a well–known algorithm.
Robust Switched Filtering for Time-Varying Polytopic Uncertain Systems
Authors: Duan Chang , Wu Fen
Published: August 2013

This paper studies the problem of designing robust switched filters for time-varying polytopic uncertain systems. The synthesis conditions for a set of filters under a min-switching rule are derived to guarantee globally asymptotical stability with optimized robust H∞ performance. Specifically, the conditions are expressed as bilinear matrix inequalities (BMIs) and can be solved by linear matrix inequality (LMI) optimization techniques. The proposed approach utilizes a piecewise quadratic Lyapunov function to reduce the conservativeness of robust filtering methods based on single Lyapunov function, thus better H∞ performance can be achieved. Both continuous and discrete-time robust filter designs are considered. To simplify filter implementation, a method to remove redundancy in min-switching filter members is also introduced. The advantages of the proposed robust switching filters are illustrated by several examples.
Galerkin Approximations for Retarded Delay Differential Equations With State-Dependent Delays
Authors: Vyasarayani C. P. , Gupta Adarsh , McPhee John
Published: August 2013

In this work, approximations for state dependent delay differential equations (DDEs) are developed using Galerkin's approach. The DDE is converted into an equivalent partial differential equation (PDE) with a moving boundary, where the length of the domain dependents on the solution of the PDE. The PDE is further reduced into a finite number of ordinary differential equations (ODEs) using Galerkin's approach with time dependent basis functions. The nonlinear boundary condition is represented by a Lagrange multiplier, whose expression is derived in closed form. We also demonstrate the validity of the developed method by comparing the numerical solution of the ODEs to that of the original DDE.
Exponential Synchronization of Stochastic Reaction-Diffusion Fuzzy Cohen-Grossberg Neural Networks With Time-Varying Delays Via Periodically Intermittent Control
Authors: Gan Qintao , Li Yang
Published: August 2013

In this paper, the exponential synchronization problem for fuzzy Cohen-Grossberg neural networks with time-varying delays, stochastic noise disturbance, and reaction-diffusion effects are investigated. By introducing a novel Lyapunov-Krasovskii functional with the idea of delay partitioning, a periodically intermittent controller is developed to derive sufficient conditions ensuring the addressed neural networks to be exponentially synchronized in terms of p-norm. The results extend and improve upon earlier work. A numerical example is provided to show the effectiveness of the proposed theories.
A Novel Constitutive Formulation for Rubberlike Materials in Thermoelasticity
Authors: Huang Zhu-Ping
Published: August 2013

The objective of this paper is to present a new framework to formulate thermoelastic constitutive relations for initially isotropic rubberlike materials undergoing finite deformations. The strain-energy function for incompressible materials is extended to include the effects of compressibility and temperature changes. The novelty of this framework is that only a few material functions and material parameters to be fitted with the experimental data are required, and these functions and parameters have clear physical meaning. In order to validate the proposed formulation, the Gent–Gent model for incompressible rubbers is chosen as an illustrative example. A new expression of the Helmholtz free energy of rubberlike materials, which takes into account the material compressibility and thermal effect, is then derived. In this generalized Gent–Gent model, only one material function and six material parameters are introduced. It is shown that the generalized Gent–Gent model can be used to predict the stress-strain behavior over the entire range of deformation. Even for incompressible materials, the strain-energy function in this paper is different from that given by Gent himself. The generalized Gent–Gent model can also adequately describe the thermal-mechanical coupling effect, in which thermoelastic inversion phenomena occur.
Integration of Nonlinear Models of Flexible Body Deformation in Multibody System Dynamics
Authors: Schulze Martin , Dietz Stefan , Burgermeister Bernhard , Tuganov Andrey , Lang Holger , Linn Joachim , Arnold Martin
Published: August 2013

Current challenges in industrial multibody system simulation are often beyond the classical range of application of existing industrial simulation tools. The present paper describes an extension of a recursive order-n multibody system (MBS) formulation to nonlinear models of flexible deformation that are of particular interest in the dynamical simulation of wind turbines. The floating frame of reference representation of flexible bodies is generalized to nonlinear structural models by a straightforward transformation of the equations of motion (EoM). The approach is discussed in detail for the integration of a recently developed discrete Cosserat rod model representing beamlike flexible structures into a general purpose MBS software package. For an efficient static and dynamic simulation, the solvers of the MBS software are adapted to the resulting class of MBS models that are characterized by a large number of degrees of freedom, stiffness, and high frequency components. As a practical example, the run-up of a simplified three-bladed wind turbine is studied where the dynamic deformations of the three blades are calculated by the Cosserat rod model.
A Matrix-Free Newton–Krylov Parallel Implicit Implementation of the Absolute Nodal Coordinate Formulation
Authors: Melanz Daniel , Khude Naresh , Jayakumar Paramsothy , Negrut Dan
Published: August 2013

This paper sets out to demonstrate three things: (i) implicit integration with absolute nodal coordinate formulation (ANCF) is effective in handling very stiff systems when an accurate computation of the sensitivity matrix is part of the solution sequence, (ii) parallel computing can provide a vehicle for ANCF to tackle very large kinematically constrained problems with millions of degrees of freedom and produce results in a matter of seconds, and (iii) large systems of equations associated with implicit integration can be solved in parallel by relying on an iterative approach that avoids costly matrix factorizations, which would be prohibitively expensive and memory intensive. For (iii), the approach adopted relies on a Krylov–subspace method that is invoked in the Newton stage at each time step of the numerical solution process. The proposed approach is validated against a commercial package and several simple systems for which analytical solutions are available. A set of numerical experiments demonstrates the scaling of the parallel solution method and provides insights in relation to the size of ANCF problems that are tractable using graphics processing unit (GPU) parallel computing and implicit numerical integration.
Parametric Flexible Multibody Model for Material Removal During Turning
Authors: Fischer Achim , Eberhard Peter , Ambrósio Jorge
Published: August 2013

This work presents a flexible multibody system model for the inside turning of thin-walled cylinders. The model accounts for the varying input and output behavior of the workpiece due to workpiece rotation and tool feed, as well as the changing workpiece dynamics due to material removal. A parametric approach is used to incorporate the effect of material removal. Hereby, a number of systems are precalculated for different machined states that are then interpolated to obtain the model for the desired machined state. As different systems typically have different vectors of degrees of freedom, a preprocessing step must be added to guarantee compatibility and thus a meaningful interpolation. In this work, two ways of obtaining a parametric model are presented that lead to similar results. The parametric model is then used to analyze stability of an inside turning operation. By taking into account the varying workpiece dynamics, an improved tool feed is suggested that would allow to greatly reduce the cycle time.
Pyrolytic Conversion of Biomass Residues to Gaseous Fuels for Electricity Generation
Authors: Davies Andrew , Soheilian Rasam , Zhuo Chuanwei , Levendis Yiannis A.
Published: August 2013

As petroleum resources are finite, it is imperative to use them wisely in energy conversion applications and, at the same time, develop alternative energy sources. Biomass is one of the renewable energy sources that can be used to partially replace fossil fuels. Biomass-based fuels can be produced domestically and can reduce dependency on fuel imports. Due to their abundant supply, and given that to an appreciable extent they can be considered carbon-neutral, their use for power generation is of technological interest. However, whereas biomasses can be directly burned in furnaces, such a conventional direct combustion technique is ill-controlled and typically produces considerable amounts of health-hazardous airborne compounds. Thus, an alternative technology for biomass utilization is described herein to address increasing energy needs in an environmentally-benign manner. More specifically, a multistep process/device is presented to accept granulated or pelletized biomass, and generate an easily-identifiable form of energy as a final product. To achieve low emissions of products of incomplete combustion, the biomass is gasified pyrolytically, mixed with air, ignited and, finally, burned in nominally premixed low-emission flames. Combustion is thus indirect, since the biomass is not directly burned, instead its gaseous pyrolyzates are burned upon mixing with air. Thereby, combustion is well-controlled and can be complete. A demonstration device has been constructed to convert the internal energy of biomass into “clean” thermal energy and, eventually to electricity.
On Approximating the Translational Velocity of Vortex Rings
Authors: Krieg Michael , Mohseni Kamran
Published: August 2013

A method is presented whereby the translational velocity of a vortex ring can be approximated from the total circulation, impulse, and kinetic energy of the vortex system. Assuming a uniform vorticity density, these bulk quantities define a unique stable vortex ring configuration, and the translational velocity can be inferred from this configuration and the system scaling. Here, the accuracy of this approximation is presented for vortex rings formed from starting jets, and the translational velocity is also characterized as it relates to the driving parameters. The translational velocity is well approximated for a wide range of experimentally generated vortex rings. It is observed that starting jets with a converging radial velocity create vortex rings with a significantly higher translational velocity. The converging radial velocity was observed to increase translational velocity by as much as 30% over parallel jet flows with identical volume flux and nozzle diameter, but the exact increase is specific to the nozzle arrangement and driving conditions.
Aluminum Catenary Production Riser: Design, Testing Results, Ways to Improvement
Authors: Tikhonov Vadim , Gelfgat Mikhail , Alikin Rudolf , Chizhikov Valery , Shaposhnikov Valery , Dias Paulo
Published: August 2013

One of the widely used systems for offshore oil production in water depths up to 500–2500 meters is a steel catenary riser (SCR). Requirements for long-term corrosion resistance of SCR are very stringent, that obliges to manufacture it from expensive steels. Still, the increased water depth leads to increased riser tension, grown pressure, aggravated buckling and oscillation problems. Among alternative materials to manufacture catenary risers, i.e., steel, titanium and aluminum alloys, the aluminum is the best from the “Strength/Weight/Cost” aspects with its high corrosion strength.

Design of an aluminum catenary production riser (ACPR) was developed in Russia; and comprehensive tests were performed on mechanical characteristics and corrosion resistance properties of ACPR tubes and their connections. Two possible connections of riser sections were considered, i.e., welded and threaded. Strength analysis of threaded connection was performed by FEM.

Mechanical testing included: testing of small samples of pipe material and welded connection cut out of riser section, testing of full-scale specimens of connection prototypes, and measurement of residual stresses. Structural and corrosion tests of samples consist of investigation of standard metallographic characteristics of pipe material and welded connection, and assessment of effects of different types of corrosion in seawater and oil fluid. The results of performed work have led to the conclusion that welded connection is most prospective for ACPR manufacturing. At the same time, the testing revealed certain improvements need to be done in the course of further work on this project.
Experimental Investigation of the Vortex-Induced Vibration of a Curved Cylinder
Authors: Assi Gustavo R. S. , Srinil Narakorn , Freire Cesar M. , Korkischko Ivan
Published: August 2013

Experiments have been conducted in a water channel in order to investigate the vortex-induced vibration (VIV) response of a rigid section of a curved circular cylinder. Two curved configurations were tested regarding the direction of the approaching flow, a concave or a convex cylinder, in addition to a straight cylinder that served as reference. Amplitude and frequency response are presented versus reduced velocity for a wide Reynolds number range between 750 and 15,000. Trajectories in the cross-flow and streamwise direction are presented as well for several reduced velocities. Results show a distinct behaviour from the typical VIV of a straight cylinder highlighting the effect of curvature on vortex formation and excitation. The concave configuration presents relatively high amplitudes of vibration that are sustained beyond the typical synchronisation region. The mechanism behind the response is not yet clear, although authors suggest it might be related to some kind of buffeting excitation due to the disturbed flow from the upstream horizontal part.
Study on the Influence of Bow Shape to the Sidestructure During Ship Collision
Authors: Liu Kun , Zhang Yangchang , Wang Zili
Published: August 2013

The problem about ship collision is the hot point of the ship mechanics. However, the research work in the past always ignored the influence of the shapes of different striking bows. The quantitative comparison analysis was performed for striking with different bow curvatures and bow angles. The results show that different shapes of the striking bows have an obvious impact on the collision capability. The smaller of the striking bulb curvatures parameter or the bigger of the striking bow angles, the deeper of the limited penetration, the higher of the collision force, the more of the energy absorption at the limited penetration.
Shielding Effect on the Overall Hydrodynamic Properties of Complex Subsea Structures
Authors: Cinello Alexandre , Pétrié François , Le Hir Eric , Molin Bernard , de Hauteclocque Guillaume
Published: August 2013

Deepwater field developments are usually associated with large submarine packages to be installed such as suction anchors, manifolds and other subsea equipment.

Key data for the lowering operation engineering are the added mass and drag coefficients of the package, which is usually a complex structure made of plates (mudmat, drop object protection…), piping and miscellaneous equipment. To extract these hydrodynamics coefficients, it is usual industry practice to consider the package overall volume or to sum the individual components coefficients which may lead to very different results.

Experimental investigations on generic complex structures have been conducted within the CITEPH project “Offshore installation of heavy package – phase II”, with the aim of better understanding the hydrodynamics coefficients to be used for the design.

This paper presents the work that has been performed during this joint industry project, in 2010/2011, with the support of TOTAL, TECHNIP, SAIPEM and DORIS Engineering, on shielding effect. In particular, model tests set-up and main results are discussed. The trends that have been found and the empirical laws that have been established as functions of dimensionless numbers are also presented.