bluuebunny/crossref_metadata_2025 huggingface dataset:
Output feedback nonlinear control of three-phase grid-connected PV generator
Authors: Yahya Abdelhafid , El Fadil Hassan , Oulcaid Mustapha
Published: January 2019

This paper addresses the problem of controlling three-phase grid connected PV system involving a PV arrays, a voltage source inverter, a grid filter and an electric grid. This paper presents three main control objectives: i) ensuring the Maximum power point tracking (MPPT) in the side of PV panels, ii) guaranteeing a power factor unit in the side of the grid, iii) and ensuring the asymptotic stability of the closed loop system. Interestingly, the present study features the achievement of the above energetic goal without resorting to sensors of currents of the grid. To this end, an output-feedback control strategy combining a state observer and a nonlinear control laws is developed. The proposed output-feedback control strategy is backed by a formal analysis showing that all control objectives are actually achieved
Critical evaluation of soft computing methods for maximum power point tracking algorithms of photovoltaic systems
Authors: Hashim Norazlan , Salam Zainal
Published: January 2019

With the proliferation of numerous soft computing (SC)–based maximum power point tracking (MPPT) algorithms for photovoltaic (PV) systems, determining which algorithm performs better than others is becoming increasingly difficult. This is primarily due to the absence of standardized methods to benchmark their performances using consistent and systematic procedures. Moreover, the module technology, power ratings, and environmental conditions reported by numerous publications all differ. Based on these concerns, this paper presents a critical evaluation of the five most important and recent SC-based MPPTs, namely, genetic algorithm (GA), cuckoo search (CS), particle swarm optimization (PSO), differential evolution (DE), and evolutionary programming (EP). To perform a fair comparison, the initialization, selection, and stopping criteria for all methods are fixed in similar conditions. Thus, the performance is determined by its respective reproduction process. Simulation tests are performed using the MATLAB/SIMULINK environment. The performance of each algorithm is compared and evaluated based on its speed of convergence, accuracy, complexity, and success rate. The results indicate that EP appears to be the most promising and encouraging SC algorithm to be used in MPPT for a PV system under the multimodal partial shading condition.
The dynamics identification of asynchronous electric drives via frequency response
Authors: Kodkin Vladimir L. , Anikin Aleksandr Sergeevich , Baldenkov Aleksandr A.
Published: January 2019

The article substantiates the necessity of identifying the dynamics of asynchronous electric drives with frequency control. It is proposed to use nonlinear transfer functions and the formula of a family of frequency responses of an electric drive, depending on the frequency of the stator voltage and slip. Experiments and simulations confirming theoretical conclusions are presented. The frequency responses of the drive of the stand calculated by the proposed method allowed to explain those problems of frequency control that were not explained by traditional methods - analytical, vector diagrams, substitution schemes, etc. This same technique allowed us to formulate a structural correction of the asynchronous electric drives. In contrast to the previously published research materials of asynchronous electric drives, a detailed qualitative analysis of the obtained nonlinear frequency responses and the interrelation of these characteristics with experimental results is shown for the first time in the article.
Proportional Resonant Controlled Dual Active Bridge DC to AC Converter System with Enhanced Response
Authors: Sowmya R. , Reddy S. Rama
Published: January 2019

This paper deals with comparison of responses of PI and Proportional Resonant controlled DC to AC Converter systems. The objective of this work is to regulate the output of Dual Active Bridge DC to DC converter (DABDAC). The input DC is converted into high frequency AC using Half bridge inverter. It is stepped up by using step up transformer and then it is rectified. The DC is converted into Low frequency AC using a Half bridge inverter. The open loop DABDAC system, closed loop PI based DABDAC system an Proportional Resonant Controller (PRC)based DABDAC system are designed, modeled and simulated using MATLAB Simulink. The results of PR controlled system are compared with those of PI controlled system. The results indicate that the proposed PRC-DABDAC has better time domain response than PI controlled DABDAC system. The proposed DABDAC system has advantages like high gain and steady state error in output voltage. 
A Novel Control Strategy for Compensation of Voltage Quality Problem in AC Drives
Authors: Suraya Syed , Sujatha P. Sujatha , Kumar P Bharat
Published: January 2019

This paper presents a novel control strategy for the compensation of voltage quality issues in power system networks with AC drives. Voltage quality is one of the key parameter for power engineers and to deliver the power with good quality should be given at most priority. Voltage quality mitigation in power system network is done by employing dynamic voltage restorer (DVR). DVR consists of power switches and power switches are to be controlled. DVR in this paper is controlled using a novel control strategy. A novel control strategy can effectively control DVR by improving voltage quality reducing the adverse effects of voltage sag and voltage swell in power system networks. The paper presents the DVR controlled with novel control strategy for electrical machine (induction motor) drive load application.
A Novel Approach in Scheduling Of the Real- Time Tasks In Heterogeneous Multicore Processor with Fuzzy Logic Technique For Micro-grid Power Management
Authors: Dhanesh Lavanya , Murugesan P.
Published: January 2019

Scheduling of tasks based on real time requirement is a major issue in the heterogeneous multicore systemsfor micro-grid power management . Heterogeneous multicore processor schedules the serial tasks in the high performance core and parallel tasks are executed on the low performance cores. The aim of this paper is to implement a scheduling algorithm based on fuzzy logic for heterogeneous multicore processor for effective micro-grid application. Real – time tasks generally have different execution time and dead line. The main idea is to use two fuzzy logic based scheduling algorithm, first is to assign priority based on execution time and deadline of the task. Second , the task which has assigned higher priority get allotted for execution in high performance core and remaining tasks which are assigned low priority get allotted in low performance cores. The main objective of this scheduling algorithm is to increase the throughput and to improve CPU utilization there by reducing the overall power consumption of the micro-grid power management systems. Test cases with different task execution time and deadline were generated to evaluate the algorithms using  MATLAB software.
Attendance Spillovers between Public and For-Profit Colleges: Evidence from Statewide Variation in Appropriations for Higher Education
Authors: Goodman Sarena , Volz Alice Henriques
Published: January 2019

Between 2000 and 2010, U.S. public colleges and universities experienced widespread and uneven changes in funding from state and local appropriations. We find that over this period annual decreases in statewide appropriations led to lower public enrollment and higher for-profit enrollment (with no effect on enrollment overall), as well as increased student borrowing. In an analysis of mechanisms, we detect effects on spending, tuition, and capacity in the public sector. Altogether, the results reveal that core institutional resources affect the types of schools that students attend and yield new evidence of substitution between the public and for-profit sectors.
Enterographa confusa sp. nov. (Roccellaceae, Arthoniales) discovered by chance in type material of its host lichen Arthonia ochraceella, described more than a century ago
Authors: VAN DEN BROECK DRIES , ERTZ DAMIEN
Published: January 2019

Enterographa confusa is described as new to science from Cuba. It is characterized by a lichenicolous habit, punctiform ascomata immersed in the host thallus, (6–)8-spored asci and 3-septate ascospores of 17–23 × (2.5–)3 µm with a distinct gelatinous sheath of 1.5(–2) µm. The new species was discovered by chance in the thallus of type material of Arthonia ochraceella, which is lectotypified here. A detailed description of this latter is also provided. Enterographa confusa can be easily overlooked because of its tiny pale ascomata similar in colour to those of its host lichen. A key to all lichenicolous Enterographa species is presented.
Almost a hundred years later, the advertisement call of Aparasphenodon brunoi Miranda-Ribeiro 1920 (Anura: Hylidae) from the Atlantic Forest
Authors: FREIRE IASODHARA RODRIGUES , THOMASSEN HANS , ROCHA PEDRO CARVALHO , LEITE FELIPE SÁ FORTES
Published: January 2019

The Neotropical genus Aparasphenodon Miranda-Ribeiro is composed of five recognized species commonly referred as “casque-headed frogs” (Frost 2018). Aparasphenodon brunoi Miranda-Ribeiro occurs in Atlantic Forest lowlands from the states of São Paulo to Bahia, Brazil (Feio et al. 1998; Mollo Neto & Teixeira Jr. 2012; Ruas et al. 2013). The biology of most Aparasphenodon species is poorly known. Within the genus, until now only Aparasphenodon arapapa Pimenta, Napoli & Haddad has its call formally described (Lourenço-de-Moraes et al., 2013, Forti et al., 2018, Guerra et al., 2018). Herein, we describe the advertisement call of Aparasphenodon brunoi Miranda-Ribeiro.
Three new species of the genus Xizicus (Orthoptera: Tettigoniidae: Meconematinae) from Taiwan
Authors: LIU JING , CHEN PO-WEI , WANG TAO , CHANG YAN-LIN
Published: January 2019

The paper reports three new species of the genus Xizicus Gorochov, 1993 (Orthoptera: Meconematini) from Taiwan, i.e. Xizicus (Eoxizicus) hsiehi sp. nov., Xizicus (Eoxizicus) dentatus sp. nov., and Xizicus (Eoxizicus) bimaculus sp. nov.
New species of Euplocania Enderlein (Psocodea, ‘Psocoptera’, Ptiloneuridae) from Brazil, with a checklist of all known species of the genus
Authors: DA SILVA NETO ALBERTO MOREIRA , ALDRETE ALFONSO N. GARCÍA , RAFAEL JOSÉ ALBERTINO
Published: January 2019

Seven new species of Brazilian Euplocania are described and illustrated, five species belong in the amabilis species group (Euplocania bujariensis n. sp., Euplocania cearaensis n. sp., Euplocania hutchingsi n. sp., Euplocania pseudopictaoides n. sp. and Euplocania xavieri n. sp.) one species belong in the marginata species group (Euplocania uariniensis n. sp.) and one species is not assignable to any of the known species groups of the genus. For this species, E. quinquedivisa n. sp., a new species group is here diagnosed, the quinquedivisa group. Information on sexes known and distribution is included for all known species of Euplocania. The first identification key to males of Euplocania species from Brazil is presented.
The Organization of Neglect: Limited Liability Companies and Housing Disinvestment
Authors: Travis Adam
Published: January 2019

Sociological accounts of urban disinvestment processes rarely assess how landlords’ variable investment strategies may be facilitated or constrained by the legal environment. Nor do they typically examine how such factors might, in turn, affect housing conditions for city dwellers. Over the past two decades, the advent and diffusion of the limited liability company (LLC) has reshaped the legal landscape of rental ownership. Increasingly, rental properties are owned by business organizations that limit investor liability, rather than by individual landlords who own property in their own names. An analysis of administrative records and survey data from Milwaukee, Wisconsin, demonstrates that signs of housing disinvestment increase when properties transition from individual to LLC ownership. This increase is not explained by selection on property characteristics or by divergent pre-transfer trends. Results affirm that real estate investors are responsive to changes in the legal environment and that the protective structure of the LLC facilitates housing disinvestment in Milwaukee. Elaborating the role of real estate investors can deepen accounts of neighborhood change processes and help explain variation in local housing conditions. Ultimately, public policies that enable business operators to circumscribe or reallocate risk may generate unintended costs for consumers and the public.
A Theory of Racialized Organizations
Authors: Ray Victor
Published: January 2019

Organizational theory scholars typically see organizations as race-neutral bureaucratic structures, while race and ethnicity scholars have largely neglected the role of organizations in the social construction of race. The theory developed in this article bridges these subfields, arguing that organizations are racial structures—cognitive schemas connecting organizational rules to social and material resources. I begin with the proposition that race is constitutive of organizational foundations, hierarchies, and processes. Next, I develop four tenets: (1) racialized organizations enhance or diminish the agency of racial groups; (2) racialized organizations legitimate the unequal distribution of resources; (3) Whiteness is a credential; and (4) the decoupling of formal rules from organizational practice is often racialized. I argue that racialization theory must account for how both state policy and individual attitudes are filtered through—and changed by—organizations. Seeing race as constitutive of organizations helps us better understand the formation and everyday functioning of organizations. Incorporating organizations into a structural theory of racial inequality can help us better understand stability, change, and the institutionalization of racial inequality. I conclude with an overview of internal and external sources of organizational change and a discussion of how the theory of racialized organizations may set the agenda for future research.
Palatal Sphincter Pharyngoplasty With Cephalic Mucosa Preservation in Selected Cases of Velopharyngeal Insufficiency
Authors: Askar Sherif M. , Quriba Amal S.
Published: January 2019

Objectives:

Sphincter pharyngoplasty is a commonly performed procedure for the treatment of velopharyngeal insufficiency and is often indicated in patients with circular or coronal closure patterns of the velopharyngeal sphincter. The authors present a modified technique of sphincter pharyngoplasty (partially mucosalized palatal sphincter pharyngoplasty [PMPSP]) in which bilateral superiorly based myomucosal palatopharyngeal flaps were elevated (in a newly designed fashion) and inserted in the palate through preformed palatal tunnels.

Methods:

This case series included 14 patients (5 male, 9 female) with persistent hypernasality who were subjected to treatment by PMPSP between May 2015 and August 2018. The palatopharyngeal flap was designed to be full thickness at its caudal segment, while its cephalic segment was denuded of its mucosa. The cephalic mucosa (of the flap) was elevated off the bed muscles as a medially based mucosa flap to be used at the end of the procedure to drape the upper part of the bed.

Results:

Pain assessed using a visual analog scale had decreased significantly at day 10 after surgery, and normal oral feeding was regained within 7 to 10 days. No major complications were recorded. Postoperative nasoendoscopic and phoniatric assessments were reported. Statistically significant improvements were reported when comparing pre- versus postoperative auditory perceptual assessment following PMPSP.

Conclusions:

The newly reported PMPSP might be a useful technique for correction of velopharyngeal insufficiency in patients with weak palatal motion (coronal or circular pattern of velopharyngeal sphincter closure). PMPSP had good reported surgical and phoniatric outcomes.
Power Analysis of Collapsed Ordered Categories with Application to Cancer Data
Authors: Maity Arnab Kumar , Dey Jyotirmoy
Published: January 2019

Ordinal data are often found in clinical studies. Sometimes the analysis of this data is done using binary logistic regression after collapsing the categories of ordinal responses. However, these analyses may not be appropriate in practice because either the assumptions are violated or because the information is lost. Cumulative logistic regression is shown to be a better alternative approach. The efficiency of cumulative logistic regression is demonstrated using simulation studies. A novel sequential testing approach is suggested in the context of cancer data. In addition, in the absence of the proper knowledge of the data, an automatic data-driven approach is also proposed. The efficacy of these proposals are illustrated via simulation studies.

AMS 2000 subject classification code: 92D99
On Log-q-Gaussian Distribution
Authors: Koike Ken-ichi , Shimegi Yuya
Published: January 2019

We propose the log- q-Gaussian distribution which is obtained as the distribution of a random variable whose logarithm is q-Gaussian. Various types of properties of the new distribution are given such as the moments, the cumulative distribution function, the extreme value distribution, the likelihood estimation, and so on. Some examples for real data are also given.

AMS Classification: 60Exx 62Exx.
Exploring the Dynamics of Deliberative Democracy in Rural India: Lessons from the Working of Gram Sabhas in India and Gram Sansads in West Bengal
Authors: Datta Prabhat Kumar
Published: January 2019

Deliberative democracy has gained considerable momentum in India in recent years in the wake of a new drive for decentralisation and democratisation to promote good governance. The constitutional amendment made in India in 1992 sought to institutionalise this concept in villages through a body called Gram Sabha (village assembly). The amendment mandates the constitution of this institution at the Gram Panchayat level (usually a cluster of villages), the functional details of which have been left to the hands of the states. The Gram Sabha is now in place in all the states though it varies from state to state in location and functions. Some states like West Bengal, have taken a step further by creating another body down the line at the level of the electoral constituency. This article presents a case study of Gram Sansads, as known in West Bengal against a general review of the working of the Gram Sabhas in India.
An Evaluation of a School-Based Savings Program and Its Effect on Sexual Risk Behaviors and Victimization Among Young Ghanaians
Authors: Masa Rainier , Chowa Gina , Sherraden Michael
Published: January 2019

The objective of this study was to examine the effect of a financial inclusion project on youth’s sexual risk behaviors and victimization. The project occurred in Ghana, where 100 schools were assigned to either a school-based savings program (SBSP), a marketing campaign, or a control group. Pretest and posttest data were collected in 2011 and 2014, respectively. Given our study objective, we restricted our sample to sexually experienced youth ( n = 957). Using doubly robust methods to estimate treatment effects, the overall financial inclusion project was not associated with positive changes in sexual risk behaviors and victimization. In contrast, SBSP was significantly associated with higher likelihood of condom use and lower probability of sexual victimization. SBSP may be another promising tool that may help young people accumulate material and nonmaterial resources to reduce sexual risk taking and victimization.
Consensus in first-order nonlinear multi-agent systems with state time delays using adaptive fuzzy wavelet networks
Authors: Taheri Mehdi , Najafi Majddedin , Sheikholeslam Farid , Zekri Maryam
Published: January 2019

In this paper, a consensus problem is addressed for first-order multi-agent systems with unknown nonlinear dynamics under undirected graphs. Adaptive fuzzy wavelet networks are used to design two novel control algorithms for nonlinear systems without delays and nonlinear systems with state time delays. In these algorithms, adaptive fuzzy wavelet networks are employed to compensate for nonlinear dynamics of systems. Using proper Lyapunov functions, adaptive laws are obtained and the uniform ultimately bounded stability of closed-loop systems is proved. In addition, this paper uses Lyapunov–Krasovskii functions to handle unknown time delays. Three simulation examples are provided to illustrate the effectiveness of the proposed control schemes.
Experiences of Adolescents and Emerging Adults Living With Type 1 Diabetes
Authors: Datye Karishma , Bonnet Kemberlee , Schlundt David , Jaser Sarah
Published: January 2019

Purpose

The purpose of this study was to identify barriers to adherence in type 1 diabetes through adolescent focus groups and to use this information to determine how diabetes educators can have a positive impact on their patients’ diabetes management.

Methods

Two focus groups were conducted with adolescents and young adults (n = 11) ages 17 to 21 with type 1 diabetes. A focus group script, which consisted of 4 open-ended questions about diabetes care and challenges associated with management of diabetes, was used to elicit discussion. The focus group transcripts were coded and analyzed using the inductive-deductive approach.

Results

Participants described unique barriers to and facilitators of self-care behaviors in their management of type 1 diabetes. A conceptual framework was developed to describe adherence to self-management in adolescents with type 1 diabetes. Biological, psychological, and environmental situational influences emerged that influence self-care behaviors. In addition, facilitators of self-care behaviors, including the health system and diabetes education, were identified, and together the interaction between situational influences, facilitators, and self-care behaviors influenced adherence to diabetes treatment.

Conclusions

The conceptual framework based on these focus groups may help diabetes educators assess and address barriers to self-care behaviors in adolescents and young adults with type 1 diabetes.
Physician and Nonphysician Estimates of Positive Predictive Value in Diagnostic v. Mass Screening Mammography: An Examination of Bayesian Reasoning
Authors: Austin Laurel C.
Published: January 2019

Background. The same test with the same result has different positive predictive values (PPVs) for people with different pretest probability of disease. Representative thinking theory suggests people are unlikely to realize this because they ignore or underweight prior beliefs when given new information (e.g., test results) or due to confusing test sensitivity (probability of positive test given disease) with PPV (probability of disease given positive test). This research examines whether physicians and MBAs intuitively know that PPV following positive mammography for an asymptomatic woman is less than PPV for a symptomatic woman and, if so, whether they correctly perceive the difference. Design. Sixty general practitioners (GPs) and 84 MBA students were given 2 vignettes of women with abnormal (positive) mammography tests: 1 with prior symptoms (diagnostic test), the other an asymptomatic woman participating in mass screening (screening test). Respondents estimated pretest and posttest probabilities. Sensitivity and specificity were neither provided nor elicited. Results. Eighty-eight percent of GPs and 46% of MBAs considered base rates and estimated PPV in diagnosis greater than PPV in screening. On average, GPs estimated a 27-point difference and MBAs an 18-point difference, compared to actual of 55 or more points. Ten percent of GPs and 46% of MBAs ignored base rates, incorrectly assessing the 2 PPVs as equal. Conclusions. Physicians and patients are better at intuitive Bayesian reasoning than is suggested by studies that make test accuracy values readily available to be confused with PPV. However, MBAs and physicians interpret a positive in screening as more similar to a positive in diagnosis than it is, with nearly half of MBAs and some physicians wrongly equating the two. This has implications for overdiagnosis and overtreatment.
School life on the margins: Slovak Roma pupils negotiating education
Authors: Payne Mark
Published: January 2019

Building on the work of Chris Searle in this journal, the author draws on an ethnographic study of a Sheffield school to examine the experiences of Slovak Roma children in the first year of secondary school as they negotiate prevailing English-only language ideologies and complex curriculum challenges and attempt to fit into an educational framework that is trying to adapt to the forces of migration and super-diversity. Struggling to engage academically, pupils are banished to the bottom sets where they are fed a watered-down curriculum. It is argued that the Roma pupils in this situation are in the exclusionary ‘anteroom’; unable to rise through the academic system, weighed down by lack of English language, an alien culture, non-white skin colour and the lack of various forms of capital prized by schools, the next logical step for many is temporary or permanent exclusion. This article sheds light on those pupils at the bottom of the heap for whom chances are curtailed, and adds to debates about xeno-racism, exclusion and class-biased pedagogies.
A Simple Technique for Diagnosing Oesophageal Intubation
Authors: Kalpokas M. , Russell W. J.
Published: January 2019

Undiagnosed oesophageal intubation during anaesthesia is a major cause of anaesthetic-related morbidity and mortality. A test was devised and evaluated to distinguish between placing an endotracheal tube in the trachea and in the oesophagus. The test involves threading a lubricated nasogastric tube through the endotracheal tube, applying continuous suction to the nasogastric tube and then attempting to withdraw the nasogastric tube. Four aspects distinguish an endotracheal tube in the trachea from one in the oesophagus: 1. the length of nasogastric tube inserted and the feel of the final obstruction to further insertion, 2. the ability to maintain unobstructed suction through the nasogastric tube, 3. the ease of withdrawal of the nasogastric tube during continuous suction, 4. the nature of any aspirate (i.e. mucus or gastric contents). An evaluation was performed on twenty patients in whom both the trachea and oesophagus were intubated simultaneously. In all twenty cases, each of the two endotracheal tubes was correctly identified as being either tracheal or oesophageal. The ability to maintain suction and the ease of withdrawal most clearly distinguished between the two positions.
Open Cardiac Compression in the Postoperative Cardiac Intensive Care Unit
Authors: Raman J. , Saldanha R. F. , Branch J. M. , Esmore D. S. , Spratt P. M. , Farnsworth A. E. , Harrison G. A. , Chang V. P. , Shanahan M. X.
Published: January 2019

Thirty-nine patients required heroic resuscitative measures for sudden hypotension and cardiac arrest in the first 72 hours following cardiac surgery between January 1, 1984 and May 31, 1988. Emergency sternotomy with open cardiac compression was performed in twenty-four of these patients when external cardiac compression failed. These were categorised as Group A. Group B comprised the fifteen patients in whom resuscitation was entirely by means of external compression and adjuvant measures. Survival with NYHA Functional Class I and II status was noted in 75% of patients in Group A, compared with 20% in Group B (P <0.002). Emergency sternotomy with open cardiac compression is an effective way of resuscitating patients in the intensive care unit in the first few days following open heart surgery.
Leg Blood Flow during Total Hip Replacement under Spinal or General Anaesthesia
Authors: Davis F. M. , Laurenson V. G. , Gillespie W. J. , Foate J. , Seagar A. D.
Published: January 2019

Calf blood flow was studied using venous occlusion impedance plethysmography during 122 total hip arthroplasties. Patients were randomly allocated to receive spinal or general anaesthesia. Blood flow was measured nine times perioperatively. In the non-surgical leg, mean blood flow rose by over 50% in both groups following anaesthetic induction, remaining significantly elevated with spinal but falling back gradually to baseline with general anaesthesia. In the surgical leg, surgical manipulations produced marked falls in flow in many patients, particularly with femoral component insertion. If this occurred, hyperaemia was commonly seen with spinal anaesthesia but rarely with general anaesthesia once the joint was relocated. Venous outflow resistance rose slightly during anaesthesia in both groups, more so with general anaesthesia. In the surgical leg, marked rises occurred with surgical manipulations, but resistance fell abruptly once the joint was relocated. No clear relationship between these observations and the occurrence of deep vein thrombosis postoperatively was established.
Mandatory Minute Volume Weaning in Patients with Pulmonary Pathology
Authors: Davis S. , Potgieter P. D. , Linton D. M.
Published: January 2019

This study evaluates mandatory minute volume (MMV) weaning in patients with pulmonary pathology. When weaning criteria were fulfilled, 22 patients were randomised to MMV and 18 to a control intermittent mandatory ventilation (IMV) group. With IMV weaning the ventilator rate was decreased by two breaths per minute at 3-4 hourly intervals during daylight hours. In the MMV group a target of 75% of the ventilator minute volume was set. All weans were considered complete four hours after the cessation of mechanical support, and were deemed successful if no further ventilation was required. The success rate was 86% in the IMV and 89% in the MMV group. MMV weaning was rapid (4.75 + 1.5 hrs) and proved less demanding on the ICU staff by providing a safe trial of spontaneous respiration, while retaining the facility for partial ventilation.
Pregnancy-Induced Hypertension: Current Concepts
Authors: Brown M. A.
Published: January 2019

This brief review outlines current concepts concerning the aetiology and pathophysiology of pregnancy-induced hypertension and, based upon these concepts, presents a plan of intensive care management for the severe forms of this condition.
A Comparison of Brachial, Femoral, and Aortic Intra-Arterial Pressures before and after Cardiopulmonary Bypass
Authors: Gravlee G. P. , Brauer S. D. , O'Rourke M. F. , Avolio A. P.
Published: January 2019

Following recent evidence that brachial and femoral artery pressures are more reliable than radial artery pressures after cardiopulmonary bypass, thirty-one adults had simultaneous pre and post-bypass measurements of brachial, femoral, and ascending aortic pressures. Two minutes after cardiopulmonary bypass, brachial artery systolic pressure and mean arterial pressure fell significantly below corresponding pressures in the femoral artery and aorta. Five minutes after cardiopulmonary bypass, only brachial artery systolic pressure was still less than femoral and aortic systolic pressures. By ten minutes after bypass, all significant pressure differences had resolved except between brachial and femoral artery systolic pressures. Clinically significant (≥ 5 mmHg) aortic-to-brachial reductions in mean arterial pressures occurred in six (19%) patients at two minutes and in three (10%) patients at five and ten minutes after bypass. Equivalent aortic-to-femoral mean pressure diminution occurred in two (6%) patients at two minutes and one (3%) patient at five and ten minutes after bypass. Neither systemic vascular resistance nor body temperatures contributed significantly to post-bypass central-to-peripheral pressure reductions. Immediately following bypass, femoral artery pressures reproduce central aortic pressures more reliably than do radial or brachial artery pressures.
Student Violence Directed Against Teachers: Victimized Teachers’ Reports to School Officials and Satisfaction With School Responses
Authors: Moon Byongook , Morash Merry , McCluskey John
Published: January 2019

Research indicates that violence against teachers has detrimental negative effects on teachers’ emotional and physical well-being, connectedness to school, job performance, and retention. However, no quantitative empirical research has been conducted to examine the extent of teacher victimization reported to school officials, school interventions to address teacher victimization, and teachers’ satisfaction with school handling of victimization. To address the limitations of prior research on teacher victimization, for a sample of 1,628 teachers in a large urban county, the present research investigates the extent of teacher victimization reported to school officials and examines school responses to teacher victimization. Furthermore, two key variables (school interventions and apologies from offending students) are tested as predictors of victimized teachers’ satisfaction with administrators’ responses to incidents. The findings indicate that the extent of reporting victimization to school officials by victimized teachers is quite high; however, a large number of victimized teachers perceived school intervention following incidents as ineffective and inadequate. Ordinal logistic regression analyses indicate that victimized teachers who report to school officials expect offending students to be disciplined and held accountable, and when this does not occur, they are dissatisfied. Overall, the findings suggest the urgent need for school administrators to review their current disciplinary policies regarding teacher-directed violence and to establish effective protocols to prevent and properly respond to teacher victimization.
Multi-fidelity validation algorithm for next generation hybrid-electric vehicle system design
Authors: Stevens Gary , Early Juliana , Cunningham Geoff , Murtagh Martin , Douglas Roy , Best Robert
Published: January 2019

With the evolution of increasingly complex hybrid-electric vehicle powertrains, the process of creating validated system models has become progressively more difficult to achieve. Increasing levels of confidence in how instantaneous vehicle energy states are captured is needed to take full advantage of the fuel consumption and emissions reduction potential of the vehicle to move towards more sustainable transportation systems. While many strategies for model validation exist, the majority rely on ascertaining comparisons with global system characteristics, for instance, total fuel consumption over a fixed driving event. However, these methods do not necessarily account for the rapidly fluctuating energy states which need to be understood to optimise the vehicle’s energy management strategy. The current work proposes a new validation approach which captures these instantaneous characteristics taking advantage of the high signal sampling rates available from modern data acquisition equipment rather than relying on drive cycle average or cumulative global behaviours. The method proposed provides a holistic view of the behaviours demonstrated by the vehicle model and identifies regions of poor system validation targeting areas for further model refinement. The algorithm is demonstrated on a new post-transmission, parallel mild-hybrid-electric bus. The model was developed in the MATLAB Simulink modelling environment. The validation algorithm is tested against vehicle dynamometer and test track data. With an increasing volume of mild and full hybrid vehicle configurations emerging, validation strategies such as the one proposed here are increasingly important for the design of energy management strategies to deliver the full potential benefits of the vehicle. The algorithm is proposed in a step by step method which can be automated to limit required user input.
Non-Destructive Identification of Spherical Inclusions
Authors: Hadjinicolaou Maria
Published: January 2019

Small coated particles and especially small coated spheres, are fundamental units in a particular class of composite materials. The physical characteristics of the core of a particle can be identified through low frequency inverse scattering techniques, in a completely non-destructive manner. Using point source, as well as, plane wave excitation, it can be identified whether the core is consisted of an acoustically soft, hard, or resistive kernel, or if it is a penetrable body having different physical characteristics from that of the coating material. Furthermore, the thickness of the shell can be evaluated assuming the physical parameters (two different densities of the two spheres) are known. Otherwise, if the thickness of the shell is known, the density ratio of the two media can be obtained from one single measurement. Consequently, the density of the core can be found when the density of the shell is known and vice versa.
On Variable Molecular Orientation in Transcrystallinity
Authors: Marom Gad
Published: January 2019

A model of variable lamella orientation in sheaf structured transcrystallinity is proposed. It describes the orientation of the c-axis of the polymer chain and of the lamellae as function of the radial distance from the fibre surface.
Analytical Fracture Mechanics Analysis of the Pull-Out Test Including the Effects of Friction and Thermal Stresses
Authors: Nairn John A.
Published: January 2019

The energy release rate for propagation of a debond in a single-fibre pull out test was derived analytically. The key finding was that an accurate analysis can be derived by a global energy analysis that includes effects of residual stresses and interfacial friction but does not need to include the details of the stress state at the interfacial crack tip. By comparison to finite elements analysis, it was verified that the analytical results are very accurate provided the debond tip is not too close to either end of the specimen. By casting the results in terms of net-specimen stress, it was possible to derive a general energy release rate result that applies to both the pull-out test and the related microbond test. The energy release rate expressions can be used to determine interfacial fracture toughness from single-fibre pull-out tests or microbond tests.
Bending Behaviour of Laminated Knitted Fabric Reinforced Beams
Authors: Huang Zheng-Ming , Teng X. C. , Ramakrishna S.
Published: January 2019

Four-point bending tests have been performed for the laminated beams reinforced in an epoxy matrix with six layers of knitted carbon fibre fabrics arranged in different orientations. It is seen that only partial layers of the beams have failed after the bending tests. The failures of all the beams were initiated from their bottom surface, i.e. due to an excessive tensile stress. Thus the failures were resulted from the matrix tensile fracture, as the epoxy tensile strength is lower than its counterpart in compression. The present experimental evidence suggests that only the use of a stress failure criterion is not sufficient in the layer-by-layer modelling for the ultimate strength of a laminate when a lateral load is involved. A critical deflection/curvature condition is also necessary.
Quantification of the Internal Topology of Continuous Fiber Composites
Authors: Barwick S.C. , Papathanasiou T.D.
Published: January 2019

We describe the usage of Large Area Automated Microscopy (LAAM) for the topological characterization of entire cross-sections of pultruded carbon fibre reinforced rods, an essential step in developing currently unavailable quantitative correlations between processing conditions and component properties. We demonstrate with three pultruded rod samples that LAAM data can be used to reconstruct the internal topology of a composite material, evaluate the degree of fibre clustering, and quantify fibre misalignment.
Dielectric Studies of Phase Morphology and Molecular Mobility in Novel Nanocomposites Based on Polyimide
Authors: Pissis P. , Kanapitsas A. , Georgoussis G. , Bershtein V.A. , Sysel P.
Published: January 2019

Broadband dielectric relaxation spectroscopy (DRS) and thermally stimulated depolarisation currents (TSDC) techniques were employed to investigate molecular mobility in relation to phase morphology in novel nanocomposites based on polyimide (PI). In addition to dielectric techniques, differential scanning calorimetry (DSC) and creep rate spectroscopy (CRS) provided information on phase transitions and relaxation behaviour of the composites. The systems investigated include nanophase-separated polyimide-silica (PI-SiO2) hybrid materials with covalent bonds between the components and rod-like polyimide (PIR) / flexible chain polyimide (PIF) molecular composites. The combination of several complementary techniques allowed to investigate the dynamic behaviour of PI in these systems in wide ranges of frequency and temperature. All the experiments indicated pronounced deviations from additivity in the dynamics of the composites. The results are discussed in terms of enhancement of small-scale motion due to loosened molecular packing of PI chains confined in nanovolumes and of reduction of large-scale chain mobility due to constraining effects and due to chemical bonds between the components.
The Effect of a Starch Envelope on Fly Ash Particles on the Impact Properties of Filled Epoxy Composites
Authors: Kishore  , Ravikumar N. L. , Sunil D.
Published: January 2019

The impact behaviour of epoxy specimens containing 20% by volume of fly ash particles without (coded, FA20) and with surface enveloped by starch in dry (FAS20) and water-ingresses (FASM20) conditions is studied. The resulting behavioural patterns are documented and compared to the composites containing as received fly ash particles. The data on unreinforced (i.e. neat) epoxy system (designated, NE) are also included. Samples with starch covering for the fillers whether tested in dry or wet conditions (i.e. FAS20 & FASM20) showed greater absorption of energy and maximum load compared to the ones derived on composites having as received fillers tested in unexposed (dry) condition (FA20). Ductility Index, D.I. on the other hand, showed a reversal in trends; the energy absorbed was highest for NE and lowest FA20 samples. Scanning microscopic examination of the fracture features was undertaken to correlate the microstructure to impact response.
Experimental Study to Illustrate Flow Control in Presence of Race Tracking Disturbances in Resin Transfer Moulding
Authors: Lawrence Jeffrey M. , Mahe Anthony , Naveen Yeshwanth Rao K. , Advani Suresh G.
Published: January 2019

To manufacture composite parts with the Resin Transfer Moulding process, a fluid resin is injected into a mould containing a fibrous preform. Often, due to variations in the preform structure, the flow behaviour can be drastically different from what was anticipated, which may not wet some of the fibrous regions causing dry spots. A common disturbance is race tracking, where the preform does not fit precisely along the mould edge. With the help of sensors, one can track the flow and measure the level of the disturbance in the mould. Decisions can be made on-line to re-direct the flow to avoid dry spots. A methodology was developed to measure the level of the race tracking and implement control actions to compensate for that race tracking disturbance. Fully automated experiments were run several times. For each experiment, although the level of race tracking was unknown beforehand, the controller properly compensated for the race tracking to successfully complete the mould filling.
A Simple Method for Theoretical Prediction of Fracture Toughness of Multilayered Composites
Authors: Kumar R. Ramesh , Dileep P.N. , Renjith S. , Rao G. Venkateswara
Published: January 2019

Intralaminar fracture toughness of a fibre-reinforced angle ply and cross ply laminates are generally obtained by testing compact tension specimen and theoretically predicted using the well-known MCCI approach. The crack initiation direction, which is treated as a branch direction for the theoretical prediction, is an apriori. A conservative estimation on the toughness value obtained by considering branch crack angle corresponding to each fibre orientation in a laminate shows a gross error with respect to test data. In the present study a new criterion for the prediction of crack initiation angle is arrived at based on Tsai-Hill minimum strain energy density criterion. This shows a very good agreement with test data available in literature on fracture toughness of various multilayered composites with large size cracks with a/w ≥ 0.3. It is interesting to note that in a multilayered composite a simple method of prediction in which crack initiation direction is assumed to be the fibre orientation that is close to the initial crack direction gives a good estimation of the intralaminar fracture toughness.
On the Young's Modulus Measurements of Ceramic and Carbon Fibres using Elastic Wave Propagation Techniques. Comparison against Quasi-Static Tensile Tests
Authors: Kostopoulos V. , Loutas T. H. , Sotiriadis G.
Published: January 2019

The Young's modulus determination of different types of ceramic fibres using both conventional quasi-static tensile tests and non-destructive elastic wave propagation techniques is the scope of the present work. A sufficient number of tensile tests were conducted on a number of different types of fibres such as carbon, Al2O3 and SiC fibre bundles and the elastic modulus was obtained. In parallel a method to determine the elastic modulus via a non-destructive approach was of primary concern due to the uncertainties of the conventional approach. To this direction the acousto-ultrasonics method proved quite capable to provide time-of-flight measurements in a rather simple experimental setup. The results seem remarkably close to the manufacturer's data and verify the method's applicability. Both techniques are analytically described with the emphasis lying on the non-destructive one. Deviations obtained from the conventional approach are thoroughly discussed and the advantages of the non-destructive technique are highlighted.
Effects of Variable Clearance in Multi-Bolt Composite Joints
Authors: McCarthy M.A. , Lawlor V.P. , Stanley W.F.
Published: January 2019

In this paper, the effects of variable clearance in multi-bolt, composite joints on load distribution, quasi-static strength and fatigue life have been studied experimentally. Both single-lap and double-lap configurations have been examined. The clearances examined ranged from neat-fit to clearances slightly larger than those allowed in the aircraft industry. Clearance has been found to have major effects on the load distribution in bolted joints, but negligible effect on ultimate strength. However, clearance had significant effects on initial failures such as bearing failure in one hole. A clearance-fit hole has been found to reduce fatigue life. The number of cycles to initiation of hole elongation under fatigue was particularly sensitive to the presence of a loose-fit hole.
Damage Modelling and Simulation of Composite Materials using Ultrasonic Measurements
Authors: Paipetis A. , Pappas Y. Z. , Vlachos D.E. , Kostopoulos V.
Published: January 2019

The monitoring of the elastic properties of Al2O3/Al2O3 composites during the exposure at high temperature environment that simulates the working conditions of a gas turbine has been performed non-destructively using ultrasonics. The applied methodology is based on velocity measurements of the elastic waves that propagate in an orthotropic medium. These were estimated experimentally using a custom pulser-receiver setup which allows control of the angle of the incident pulse on the sample, while the latter is immersed in a water bath. The derivation of the elastic constants in order to reproduce the stiffness matrix of the composite is an inverse wave propagation problem described by the Christoffel equation. The damage initiation and propagation as depicted by the deterioration of the moduli of the material was described using deterministic and stochastic approaches. Finally, the damage accumulation process was simulated as a Markov process.