bluuebunny/crossref_metadata_2025 huggingface dataset:
The Economic and Social Impacts of Migration on Brand Expenditure: Evidence from Rural India
Authors: Narayan Vishal , Kankanhalli Shreya
Published: May 2021

Households that send members to work away from home often receive information about the lifestyles and consumption behaviors in those migration destinations (i.e., social remittances) along with money or goods (i.e., economic remittances). The authors investigate the effect of having a migrant household member on household brand expenditures in rural India, a market characterized by substantial consumption of unbranded products. They collect and analyze household-level survey data from 434 households across 30 villages using an instrumental variable strategy. Economic remittances result in greater brand expenditure, and this level is higher for poorer households. After controlling for economic remittances, the authors find that the effect of migration on brand expenditures is more positive for households in more populous villages, with greater access to mobile phones, lower viewership of television media, and less recently departed migrants. They demonstrate how marketing resource allocation across villages can be improved by incorporating migration data and provide insights for household targeting in the context of door-to-door selling in villages. The results are robust to alternative, public policy–based instruments and can be generalized to expenditure on private schools. Using additional survey data from 300 households in 62 new villages, the authors replicate the results by comparing within-households brand expenditures before and after the migration event.
Increasing Team Performance by Sharing Success
Authors: Chen Hua , Chung Kevin
Published: May 2021

When using group-based commission plans to motivate their sales force, should firms always compensate salespeople based on the average of team members’ sales outcomes? The theory suggests that when team members are heterogeneous in sales abilities, the proposed maximum contract (where the team output is set by the largest individual sales output) dominates the average contract (where the team output is determined by the average output of team members) in terms of overall team effort. This is because the stronger team member will exert higher effort under the maximum contract compared with the average contract, and this increase exceeds the decrease in the weaker team member’s effort. The authors validate the theoretical predictions by employing two laboratory experiments to provide a causal test of the theory and two randomized field experiments to deliver additional corroborating evidence. Overall, the experimental results are consistent and broadly confirm the theoretical predictions, pointing to the substantial gains from implementing the maximum contract when team members are heterogeneous in abilities. Interestingly, the weaker team members exert similar effort across the maximum and average contracts, although the theory predicts higher effort under the latter.
Boundaries in the Making: Transformations in Erving Goffman’s Total Institution through the Case of a Female Benedictine Monastery
Authors: Clot-Garrell Anna
Published: May 2021

Total institutions have undergone profound changes since Erving Goffman published his seminal work Asylums in 1961. This article explores the persistence and transformation of total institutions under late-modern conditions. Based upon empirical research conducted in a female Benedictine monastery, I analyse changes in the physically bounded structure of a total institution. Specifically, I address the trend towards greater permeability and flexibility of enclosed total spaces. Inspired by Georg Simmel’s spatial insights, I examine how boundaries are historically reshaped through changing relations of distance and proximity to wider society, and how these shifts alter the material expression and configuration of power that originally characterised the monastery’s totality. This article claims the ongoing relevance of Goffman’s conceptualisation to accommodate such modifications and illustrates how, in certain cases, adaptations of total institutions to contemporary conditions can be understood as involving the reconfiguration, rather than the dismantling, of totality.
Promoting a safer Church? A critical discourse analysis of the Church of England’s safeguarding policy document
Authors: Sidebotham Peter
Published: May 2021

This article examines, by using principles of critical discourse analysis, the safeguarding policy of the Church of England as presented in the policy document Promoting a Safer Church. Overall, the document provides a succinct and comprehensive outline of the Church of England’s safeguarding policy, setting out a broad and whole-church approach to safeguarding that encompasses activities from prevention through to response and taking seriously the concerns of those who have been abused within the institution of the Church. However, the analysis also reveals some weaknesses of definition and accountability and an ongoing need, as highlighted by the recent Independent Inquiry into Child Sexual Abuse report, for a change in culture and behaviour within the Church.
Supporting Real World Decision Making in Coronary Diseases Using Machine Learning
Authors: Kokol Peter , Jurman Jan , Bogovič Tajda , Završnik Tadej , Završnik Jernej , Blažun Vošner Helena
Published: May 2021

Cardiovascular diseases are one of the leading global causes of death. Following the positive experiences with machine learning in medicine we performed a study in which we assessed how machine learning can support decision making regarding coronary artery diseases. While a plethora of studies reported high accuracy rates of machine learning algorithms (MLA) in medical applications, the majority of the studies used the cleansed medical data bases without the presence of the “real world noise.” Contrary, the aim of our study was to perform machine learning on the routinely collected Anonymous Cardiovascular Database (ACD), extracted directly from a hospital information system of the University Medical Centre Maribor). Many studies used tens of different machine learning approaches with substantially varying results regarding accuracy (ACU), hence they were not usable as a base to validate the results of our study. Thus, we decided, that our study will be performed in the 2 phases. During the first phase we trained the different MLAs on a comparable University of California Irvine UCI Heart Disease Dataset. The aim of this phase was first to define the “standard” ACU values and second to reduce the set of all MLAs to the most appropriate candidates to be used on the ACD, during the second phase. Seven MLAs were selected and the standard ACUs for the 2-class diagnosis were 0.85. Surprisingly, the same MLAs achieved the ACUs around 0.96 on the ACD. A general comparison of both databases revealed that different machine learning algorithms performance differ significantly. The accuracy on the ACD reached the highest levels using decision trees and neural networks while Liner regression and AdaBoost performed best in UCI database. This might indicate that decision trees based algorithms and neural networks are better in coping with real world not “noise free” clinical data and could successfully support decision making concerned with coronary diseasesmachine learning.
Pediatric Oral Neurovascular Hamartoma of the Hard Palate: A Clinicopathologic Report
Authors: Roy Catherine F. , Khalife Sarah , Kuk Mariya , Nguyen Van-Hung , Daniel Sam J.
Published: May 2021

We hereby present the first-reported pediatric case of a hard palate neurovascular hamartoma in a male newborn, in which the diagnosis was established following an initial nondiagnostic biopsy, extensive radiological investigations, and eventual wide local excision. These benign lesions can easily be mistaken for malignant diagnoses, leading to increased parental and child anxiety as well as avoidable diagnostic and therapeutic interventions.
Do Spousal Intimate Relationships Affect Fertility Intentions and Preferences?
Authors: Erfani Amir , Jahanbakhsh Roya
Published: May 2021

The fertility influence of spousal intimate relationships is unknown. Drawing on the Giddens’s theory of transformation of intimacy, this study proposed a hypothesis that couples supporting egalitarian intimate relationships, with a greater risk profile attached to the relationship, and having less attachments to the external normative pressures shaping marital relations, are more likely to have low-fertility intentions and preferences. Using data from a self-administered pilot survey ( n = 375 prospective grooms and brides) designed by the authors, and employing multivariate regression models, we found that the lower attachment to external social forces in mate selection was associated with the lower ideal number of children, and those with a greater spousal relational egalitarianism and a higher risk profile attached to their relationships preferred lower number of children and were less likely to intend to have children after marriage. The study sheds new light on the determinants of low fertility.
Pediatric End of Life Care: Impact of Islamic Faith
Authors: Hafez Shahad A. , Snethen Julia A. , Ngui Emmanuel , Ellis Julie , Taani Murad
Published: May 2021

Studies investigating children and families’ experiences at end of life in Saudi Arabia are limited. However, one factor found to have an impact on patient and primary caregiver end of life care is Islam. Since women are the primary caregivers for children in Saudi Arabia, the purpose of this study was to explore the perceptions of Muslim women caring for a child at end of life. Using a qualitative approach, interviews were conducted with 24 female primary caregivers caring for a child at end of life. Thematic analysis was used to analyze the data. The researchers found that Islamic beliefs and practices had a positive influence on primary caregivers’ experiences. Islamic beliefs and practices helped support participants through their child’s end of life experience. Results have implications for health care education, practice, policy, and future research on end of life in Saudi Arabia other Muslim countries.
COVID-19 and vision impairment: Constraints negotiation, participation, and well-being during lockdown in the United Kingdom
Authors: Halpern Nigel , Rickly Jillian M , Hansen Marcus , Fellenor John
Published: May 2021

In response to the Coronavirus disease, the United Kingdom (UK) government introduced lockdown measures requiring people to isolate and adhere to social distancing. This article uses Constraints Negotiation Theory to examine effects of the lockdown on people with vision impairment (PwVI). The research is based on an online survey of 639 PwVI in the UK. The analysis was conducted using partial least squares structural equation modelling in SmartPLS. The findings show that the lockdown had a negative effect on the participation and well-being of PwVI. However, they also show that the negative effects could be negotiated by adapting activities. This emphasises the need for a more inclusive response to current or future pandemics that recognises the vulnerabilities of PwVI and helps them to overcome the challenges associated with any measures that are introduced.
“Making do with things we cannot change”: An interpretive phenomenological analysis of relationship resilience among gay men in Singapore
Authors: Bin Ibrahim Muhamad Alif , Barlas Joanna
Published: May 2021

Despite evolving social and political attitudes, many countries, including Singapore, still do not recognize couples in same-sex relationships. Much remains to be understood about the processes and strategies that help these couples maintain their relationships, especially in Asian societies. This study explored the ways in which gay men in intimate relationships safeguarded their relationships and remained resilient in Singapore. Semi-structured interviews were conducted with nine gay men in long-term relationships. The data were analyzed using interpretive phenomenological analysis. The analysis generated three superordinate themes, a) Making do with things we cannot change, b) Remaining resilient through social and financial capital, and c) Our love is stronger than the challenges we face. The emergent themes pointed to the ways in which participants coped with or shielded themselves against socio-political stressors that negatively impacted their relationships in the Singapore context. While some participants sought solace in families of choice, many learned to accept socio-political situations beyond their control. Most participants made do with implicit recognition as they were unwilling to disrupt social harmony. Others used their financial security to overcome structural barriers such as obtaining legal elements of heterosexual marriage. Findings may further current understanding of the ways in which gay couples remain resilient despite the relational challenges in different cultural contexts.
Work-to-family conflict and firm performance of women entrepreneurs: Roles of work-related emotional exhaustion and competitive hostility
Authors: De Clercq Dirk , Kaciak Eugene , Thongpapanl Narongsak (Tek)
Published: May 2021

When entrepreneurs suffer from work-to-family conflict, it can affect firm performance. This article considers how emotional exhaustion experienced in the course of running a business mediates this link and how beliefs about competitive hostility invigorate that effect. Using survey data collected from 200 women entrepreneurs in Ethiopia, a country marked by culturally traditional gender role expectations, the empirical findings show that a sense of being emotionally overextended, due to the demands of running a firm, creates a conduit for the negative interference of the family upon the firm. This escalates into diminished firm performance. The results also demonstrate that this conduit is particularly prominent when entrepreneurs feel more threatened by hostile market environments. For entrepreneurship scholarship and practice, this article establishes two notable factors; a feeling of being ‘worn out’ by the business and adverse competitive markets. These factors clarify the complex link between work-induced family strain and business performance for women entrepreneurs, who might be particularly challenged when balancing time demands in gender-discriminatory environments.
Institutional repositories in Africa: Regaining direction
Authors: Adam Usman Ahmed , Kaur Kiran
Published: May 2021

Institutional repositories are powerful tools to facilitate global access to intellectual output by members of the institution, particularly in assisting them to preserve and maximize access to their research output globally. This exploratory study of the status of institutional repositories implementation in African countries using the global Directory of Open Access Repositories (OpenDOAR) and Transparent Ranking: All Repositories by Google Scholar, reports on the operational status and the performance of repositories. Factor analysis and cluster analysis are used to analyze the operational level of institutional repositories in African countries. The analysis showed that the typical performance of institutional repositories remains below average. The possibility of global open access to research results through institutional repositories in South Africa, Kenya, Nigeria, Algeria, Sudan, and Egypt appeared to be relatively more feasible than other African countries. This study concludes that many organizations, institutions, and societies spend great efforts in support of open access implementation in Africa, however, the widespread implementation of institutional repositories is still very slow paced, and the performance of the implemented repositories was below expectation. Suggestions for regaining the intended direction of African institutional repositories are given based on the current status.
Acute micro-thrombosis after subarachnoid hemorrhage: A new therapeutic target?
Authors: Ye Fenghui , Keep Richard F , Hua Ya , Garton Hugh JL , Xi Guohua
Published: May 2021

Microthrombi formation in the brain following subarachnoid hemorrhage (SAH) has been recognized and suspected to contribute to cerebral ischemia. A recent study found that ultra-early cerebral micro-thrombosis occured four hours after experimental SAH. The number of thrombotic microvessels correlated with brain-blood barrier disruption and neuronal injury. If acute cerebral micro-thrombi also occur in humans, is it time to develop a therapy with systemic thrombolysis for SAH patients?
Reproducibility of findings in modern PET neuroimaging: insight from the NRM2018 grand challenge
Authors: Veronese Mattia , Rizzo Gaia , Belzunce Martin , Schubert Julia , Searle Graham , Whittington Alex , Mansur Ayla , Dunn Joel , Reader Andrew , Gunn Roger N ,   and the Grand Challenge Participants
Published: May 2021

The reproducibility of findings is a compelling methodological problem that the neuroimaging community is facing these days. The lack of standardized pipelines for image processing, quantification and statistics plays a major role in the variability and interpretation of results, even when the same data are analysed. This problem is well-known in MRI studies, where the indisputable value of the method has been complicated by a number of studies that produce discrepant results. However, any research domain with complex data and flexible analytical procedures can experience a similar lack of reproducibility. In this paper we investigate this issue for brain PET imaging. During the 2018 NeuroReceptor Mapping conference, the brain PET community was challenged with a computational contest involving a simulated neurotransmitter release experiment. Fourteen international teams analysed the same imaging dataset, for which the ground-truth was known. Despite a plurality of methods, the solutions were consistent across participants, although not identical. These results should create awareness that the increased sharing of PET data alone will only be one component of enhancing confidence in neuroimaging results and that it will be important to complement this with full details of the analysis pipelines and procedures that have been used to quantify data.
Association between pre-treatment perfusion profile and cerebral edema after reperfusion therapies in ischemic stroke
Authors: Ng Felix C , Churilov Leonid , Yassi Nawaf , Kleinig Timothy J , Thijs Vincent , Wu Teddy Y , Shah Darshan , Dewey Helen M , Sharma Gagan , Desmond Patricia M , Yan Bernard , Parsons Mark W , Donnan Geoffrey A , Davis Stephen M , Mitchell Peter J , Campbell Bruce CV
Published: May 2021

The relationship between reperfusion and edema is unclear, with experimental and clinical data yielding conflicting results. We investigated whether the extent of salvageable and irreversibly-injured tissue at baseline influenced the effect of therapeutic reperfusion on cerebral edema. In a pooled analysis of 415 patients with anterior circulation large vessel occlusion from the Tenecteplase-versus-Alteplase-before-Endovascular-Therapy-for-Ischemic-Stroke (EXTEND-IA TNK) part 1 and 2 trials, associations between core and mismatch volume on pre-treatment CT-Perfusion with cerebral edema at 24-hours, and their interactions with reperfusion were tested. Core volume was associated with increased edema (p < 0.001) with no significant interaction with reperfusion (p = 0.82). In comparison, a significant interaction between reperfusion and mismatch volume (p = 0.03) was observed: Mismatch volume was associated with increased edema in the absence of reperfusion (p = 0.009) but not with reperfusion (p = 0.27). When mismatch volume was dichotomized at the median (102 ml), reperfusion was associated with reduced edema in patients with large mismatch volume (p < 0.001) but not with smaller mismatch volume (p = 0.35). The effect of reperfusion on edema may be variable and dependent on the physiological state of the cerebral tissue. In patients with small to moderate ischemic core volume, the benefit of reperfusion in reducing edema is related to penumbral salvage.
Kalman Filtering Method for Real-Time Queue Length Estimation in a Connected Vehicle Environment
Authors: Wang Yi , Yao Zhihong , Cheng Yang , Jiang Yangsheng , Ran Bin
Published: May 2021

Queue length estimation is of great importance for measuring traffic signal performance and optimizing traffic signal timing plans. With the development of connected vehicle (CV) technology, using mobile CV data instead of fixed detector data to estimate queue length has become an important research topic. This study focuses on real-time queue length estimation for an isolated intersection with CV data. A Kalman filtering method is proposed to estimate the queue length in real time using traffic signal timing and real-time traffic flow parameters (i.e., saturated flow rate, traffic volume, and penetration rate), which are estimated using CV trajectories data. A simulation intersection was built and calibrated using field data to evaluate the performance of the proposed method and the benchmark method. Results show that when the CV penetration rate is at 30%, the average values of mean absolute errors, mean absolute percentage errors, and root mean square errors are just 1.6 vehicles, 20.9%, and 2.5 vehicles, respectively. The performance of the proposed model is also better than the benchmark method when the penetration rate of CVs is higher than 20%, which proves the validity of the proposed method. Furthermore, sensitivity analysis indicates that the proposed method requires a high penetration rate of at least 30%.
Successful use of CytoSorb in a Covid-19 patient with secondary septic shock due to a sacral decubitus infection
Authors: Pancani Flavia , Pavani Raffaella , Quacquarelli Antonio , Feri Marco
Published: May 2021

Septic shock is a clinical condition with high mortality (40%–70%) and morbidity. During septic shock, there is a significant release of cytokines and other inflammatory mediators that can cause damage to different organs, known as a “cytokine storm.” The cytokine storm can cause hypotension, tissue damage, metabolic acidosis, and renal failure. This clinical picture also seems to be confirmed in the context of Covid-19 patients. Hemoadsorption with CytoSorb represents an adjunctive therapy to attenuate the systemic inflammatory process and helps restore a balanced immune response. We present the clinical case of a 75-year-old man, admitted to our hospital with respiratory failure due to Sars-CoV-2 infection and secondary septic shock due to a sacral decubitus. On admission the patient presented with a clinical picture of mixed acidosis with high levels of lactate and inflammatory indexes. Simultaneously along with antibiotic therapy, we started hemoadsorption treatment with CytoSorb in combination with continuous venous-venous hemodiafiltration. At the end of the treatment the patient had recovered his vital functions and the infection was successfully treated. Use of the CytoSorb device in a Covid-19 positive patient was safe and well-tolerated. Early treatment with CytoSorb decreased interleukin 6 plasma levels and inflammatory indexes, resulting in earlier stabilization of homeostasis. This case report suggests that the use of CytoSorb could be a possible adjuvant therapy in patients with septic shock even when affected by Covid-19.
The Psychological Foundations of Management in Family Firms: Emotions, Memories, and Experiences
Authors: Humphrey Ronald H. , Massis Alfredo De , Picone Pasquale Massimo , Tang Yi , Piccolo Ronald F.
Published: May 2021

Exploring the psychological foundations of management in family firms is necessary to understand why they formulate and implement strategies differently from nonfamily firms, and why and how family firm behavior varies across different family firms. Picone et al. (2021. The psychological foundations of management in family firms: Values, biases, and heuristics. Family Business Review, 34(1), 12-32) have proposed a conceptual framework for the psychological foundations of management in family business, examining how the values, biases, and heuristics of family firm members affect strategic decision-making and family firm outcomes. Drawing on this framework, we examine emotions, memories, and experiences in family firms, disentangling “what we know” from “what we should know”, and offering some relevant questions to advance the field.
Characteristics of Sexual and Gender Minority Caregivers of People With Dementia
Authors: Anderson Joel G. , Flatt Jason D. , Jabson Tree Jennifer M. , Gross Alden L. , Rose Karen M.
Published: May 2021

Objectives: Given what little is known about the experiences of sexual and gender minority (SGM) caregivers of people with Alzheimer’s disease and related dementias (ADRD), the aim of the current study was to describe psychosocial measures among these caregivers. Methods: We used an online survey and social media recruitment strategies. Results: Of 286 caregivers, the majority were gay men. Most respondents were white, with a third identifying as Latino American. The plurality of caregivers identified as a spouse/partner and were providing care for someone who identified as a sexual minority; one-fifth cared for someone transgender. Sexual orientation, perceived stress, caregiver stigma, and microaggressions were psychosocial factors associated with family quality of life and depressive symptoms in the caregivers. Discussion: This study is the first to provide a focused description of the characteristics and psychosocial needs of SGM caregivers of someone with ADRD, supporting development of targeted interventions for this population.
The relatable entrepreneur: Combating stereotypes in entrepreneurship education
Authors: Raible Stephanie E , Williams-Middleton Karen
Published: May 2021

Despite an estimated 582 million entrepreneurs globally, stereotypes plague the social cognitive concept of “the entrepreneur,” shaping assumptions of what entrepreneurship is while being far from representative of possible entrepreneurial identities. “Heroic” stereotypes of entrepreneurs (e.g., Steve Jobs or Elon Musk) stemming from the popular media shape the assumptions of students entering entrepreneurship classrooms. These stereotypes are strong and limiting, framing entrepreneurship as attainable only through exceptional skill and talent, and are often characterized by exclusively masculine qualities. Involving identity work in entrepreneurship education can expose the limitations that stereotypes impose on students aspiring to be entrepreneurs and introduce more heterogeneity. The use of narrative cases allows educators to facilitate a threefold approach: (1) raising awareness of stereotypes, (2) creating a structure for more realistic examples and socialization through narrative comparisons and (3) teaching students the basics of identity management for sustaining their entrepreneurial careers. The approach encourages direct conversations about what is—and who can become—an entrepreneur and reveals the limiting beliefs that students may bring with them into the classroom. Such discussion informs the educator on how to foster students’ entrepreneurial identity and empower their identity management.
Correlated disorder in rainbow metamaterials for vibration attenuation
Authors: Fabro AT , Meng H , Chronopoulos D
Published: May 2021

Metastructures are typically composed of periodic unit cells designed to present enhanced dynamic properties in which either single or multiple resonators are periodically distributed. Even though the periodic metamaterials can obtain bandgaps with outstanding vibration attenuation, the widths of bandgaps can still be narrow for some practical applications. Rainbow metamaterials have been proposed based on gradient or random profiles to provide further improved attenuation. Nonetheless, the effects of correlated random disorder on their attenuation performance remains an open challenge. This work presents an investigation on the effects of correlated disorder on the vibration attenuation of rainbow metamaterials. An analytical model using the transfer matrix approach is used to calculate the receptance functions in a finite length metastructure composed of evenly spaced non-symmetric resonators attached to a beam with Π-shaped cross-section, thus a multi-frequency metastructure. The correlated disorder is modelled using random fields and an analytical expression of the Karhunen-Loève expansion is used such that spatial correlation on the resonator properties is modified by various correlation lengths, i.e., the level of spatial smoothness. Individual samples of random fields are used to investigate the effects of the correlated disorder in the vibration attenuation of a multi-frequency metastructure. It is shown that the bandgap can be further widened when compared to uncorrelated disorder. The obtained results indicates that a combination of the gradient profile with some level of disorder, typically resulting from random fields with larger correlation lengths, tends to give improved vibration attenuation when compared to a optimized gradient rainbow metamaterial. It opens new and innovative ways for the design of broadband rainbow metastructures for vibration attenuation.
Numerical and experimental study of electromagnetic induction heating process for bolted flange joints
Authors: Liu Zhufeng , Xie Yonghui , Ye Xiaolong , Wang Jun , Liu Bin
Published: May 2021

As a promising metalwork processing technology, electromagnetic induction heating (EMIH) method has been applied in dealing with bolted flange joints in turbomachinery. In this study, a 3-D finite element model of electromagnetic induction heating system for the bolted flange joint is established, and the specific governing equations are derived based on Maxwell’s principle. The alternately-coupled magneto-thermal analysis is carried out considering temperature-dependent material properties to obtain the temperature distribution, followed with the uncoupled thermal-mechanical analysis to acquire the axial stress and deformation in EMIH process. The magnetic induction intensity mainly concentrates at the inner wall region, attenuates seriously along the radial direction, and reduces to almost zero at the outer wall. Due to the skin effect, the heat transfers radially and axially outward, indicating a diamondlike-shaped development from the center to the surrounding region. The axial stress with and without initial pretension are also discussed respectively. Then the corresponding experiments are introduced and carried out to validate the reliability of numerical simulation results. By comparing the results of the center point of inner surface and outer surface, the numerical simulation is proved reliable with a 5∼10% reasonable deviation. Further, the induction heating process has been improved through the optimization method based on pattern search algorithm. By adopting the stepped input current density optimized in the study, the optimal thermal stress tends to be constant and the final heating time reduces by 20.5% in the safe range of stress.
High temperature effect on quasi-static and low velocity impact behaviors of advanced composite materials
Authors: Karakuzu Ramazan , Djele Akim , Dogan Akar
Published: May 2021

In this study, the effect of ambient temperatures on the punch shear and low-velocity impact behavior of S2 glass fabric and carbon-kevlar hybrid fabric reinforced epoxy composites was investigated. The quasi-static tests (QST) were performed by using a Universal Shimadzu Tensile Testing Machine with various crosshead speeds. Low-velocity impact (LVI) tests were also carried out by using the CEAST Fractovis Plus impact test machine at different impact energies. Flat-nose impactors with a cylindrical punch diameter of 12.70 mm were mounted to the test machines. Both tests have been carried out at various temperatures. After the experiments, the load-displacement, the absorbed energy-impact energy/crosshead speed and punch shear strength graphs are plotted. From the obtained results it can be said that, in penetration cases of low-velocity impact and quasi-static tests, absorbed energy and punch shear strength values show similar behavior for hybrid carbon-kevlar/epoxy at each temperature except for 80 °C while these values are different from each other for S2 glass/epoxy at all temperatures.
Stages prediction of the remaining useful life of rolling bearing based on regularized extreme learning machine
Authors: Wu Chenchen , Sun Hongchun , Zhang Zihan
Published: May 2021

The prediction of the remaining useful life (RUL) of rolling bearings is an important means to ensure the rotating machinery's safe operation. At present, most of the proposed methods use direct prediction based on bearing vibration signals, which not only have low prediction accuracy but also time-consuming. This paper proposes a staged prediction method, and the regularized learning machine (RELM) based on the proposed sensitive degradation feature is applied to predict RUL of the bearing with high accuracy and speed. Firstly, the relative root mean square value (RRMS) is used to divide the degradation stages of rolling bearings. Secondly, the RRMS indicator is used for multi-step time series prediction in the normal phase of the bearing. Thirdly, in the bearing's degradation stage, the Pearson Correlation Coefficient (PCC) Combined Entropy Weight Method (EWM) feature selection criterion is proposed to predict the RUL of the rolling bearing. Finally, the sensitive degradation feature of the bearing vibration signals is input into RELM to predict the RUL. The bearing data sets of PHM Challenging 2012 are used to verify the effectiveness of the proposed method. Three comparative experiments have been verified to prove the accuracy and rapidity of the proposed method in time series forecasting.
Numerical investigation on the performance of impeller back seal configuration in a supercritical CO2 radial-inflow turbine
Authors: Du Qiuwan , Wang Yuqi , Zhang Di , Xie Yonghui
Published: May 2021

Radial-inflow turbine is a core component in supercritical CO2 (SCO2) Brayton cycle. The leakage from the nozzle outlet towards the impeller back brings a great challenge to the efficiency and security of the power system. In this paper, the labyrinth seal (LS) and dry gas seal (DGS) are arranged on the impeller back of a SCO2 radial-inflow turbine and the influence on the comprehensive performance is investigated. Results demonstrate that both LS and DGS configurations can significantly reduce leakage of the impeller back and DGS configuration performs better. Compared with the configuration without leakage, the power and efficiency of DGS configuration are only reduced by 0.27% and 0.35% respectively. The seal clearance and the inlet width have a greater effect on LS configuration. The thermo-mechanical seal deformation values of DGS configurations are all less than 8 μm, which verifies the feasibility. Finally, a novel combined seal configuration with both LS and DGS is proposed and excellent performance is achieved, providing a potential approach for the sealing problem of SCO2 radial-inflow turbine.
A comprehensive review on the effect of precipitation on mechanical properties of friction stir welded aluminium alloys
Authors: Shyamlal C , Rajesh S , Suresh Kumar S
Published: May 2021

Friction Stir Welding (FSW) is one of the excellent metals joining processes in terms of joint strength efficiency, quality of the weld and eco-friendliness. The strength of the joint and quality of the weld depend upon the FSW processing parameters. This paper aims to provide overview of the FSW process by considering the effect of alloying elements and its precipitates on mechanical properties of aluminium and its alloys. The importance of grain growth and its effect on mechanical properties after welding is also analysed and discussed in detail. The interesting observation is that the precipitates and its size, residual stress play an important role in changing the hardness, tensile strength and fatigue strength across the weld zones. In general, the hardness of the stir zone is lesser when compared to base metal and this is noticed for all series of aluminium and its alloys, irrespective of the precipitates and its structure. Grain size and its morphology also have significant role in affecting the mechanical properties of the welded joint and it is found that post welding process has noticeable effect on the mechanical properties closer to base aluminium and its alloys.
Research on the self-powered downhole vibration sensor based on triboelectric nanogenerator
Authors: Chuan Wu , He Huang , Shuo Yang , Chenxing Fan
Published: May 2021

Drill string vibration during the drilling must be measured in real-time as it will cause damage to the construction. This paper proposed a self-powered downhole vibration sensor based on the triboelectric nanogenerator. The downhole vibration sensor relies on the drill string vibration to induce triboelectric charge and electrostatic induction of nanomaterials, thereby realizing self-powered vibration measurement. Sensing performance test results show that the measurement range is between 0 to 5 Hz, the measurement error does not exceed 3.5%, and the output voltage amplitude with a range of 2 V to 5.5 V decreases with the increases of vibration frequency. Self-powered performance test results show that the output current can reach a maximum value of about 35 × E−8 A when a 50 ohm resistance is connected in series, the output power can reach a maximum value of about 924.5 × E−12 W when a 20k ohm resistance is connected in series at a vibration frequency of 0.8 Hz, and the output current and power all decrease with the increase of the vibration frequency.
A new combined braking approach of magnetorheological fluids brake based on fuzzy controller and improved PID controller
Authors: Hua Dezheng , Liu Xinhua , Gupta Munish Kumar , Fracz Pawel , Li Zhixiong
Published: May 2021

With the aim to improve working performance of magnetorheological fluids (MRF) brake, a combined braking approach is proposed in this paper. A data acquisition system of MRF brake is designed and transfer function is identiﬁed for the device. Furthermore, based on the excitation current-extrusion pressure combined braking system, a fuzzy controller is designed to distribute the target torque. Moreover, through integration of fruit fly optimization algorithm (FOA) and particle swarm optimization algorithm (PSOA), an improved proportional-integral-differential (PID) controller is presented to conduct braking mechanism. Finally, the simulations and experiments are carried out. The results show that the combined braking approach with fuzzy controller and improved PID controller has characteristics of quick response and no overshoot, and superior to conventional PID and FOA PID controller.
On the concept of embedded resonators for passive vibration control of tyres
Authors: Errico F , Petrone G , Rosa S De , Franco F , Ichchou M
Published: May 2021

An investigation is carried out on structure-borne vibrations of tyre models at low frequencies. The idea is to use embedded resonant meta-materials to damp the tyres’ vibrations and thus reduce the transferred energy to the main attached structures. A simplified tyre model is used, being the investigation of the effects of the embedded substructures the main target of the work; internal pressure and tyre rotation effects are neglected at this stage. Different configurations are tested targeting different natural modes of the tyre, while mechanical excitation is assumed on one section of the tyres. The results show how the proposed designs open new possible and feasible solutions for the vibration control.
Waypoint following dynamics of a quaternion error feedback attitude control system
Authors: Karpenko Mark , Halverson Julie K. , Besser Rebecca
Published: May 2021

Closed-loop attitude steering is a concept for implementing an attitude trajectory by using a conventional quaternion error feedback controller to track the time-varying attitude reference, rather than to simply regulate to a desired orientation. This is done by sampling the reference input and executing the maneuver as a sequence of closely spaced regulating commands that are read out from the spacecraft’s command buffer. The idea has been employed in practice to perform zero-propellant maneuvers on the International Space Station and minimum-time maneuvers on NASA’s TRACE space telescope as well as NASA’s Lunar Reconnaissance Orbiter (LRO). A challenge for operational implementation of the idea is the limited capacity of a space vehicle’s command storage buffer, which is normally not designed with attitude tracking in mind. One approach to mitigate the problem is to downsample-and-hold the attitude commands so that the attitude control system (ACS) regulates to a series of waypoints. This article explores the waypoint following dynamics of a quaternion error feedback control law for such an approach. It is shown that downsample-and-hold induces a ripple between downsamples that causes the satellite angular rate to significantly overshoot the desired limit. Analysis in the z-domain is carried out in order to understand the phenomenon. An interpolating Chebyshev-type filter is proposed that allows the desired attitude trajectory to alternatively be encoded in terms of a small set of filter coefficients. Using the interpolating filter, the continuous-time reference trajectory can be reconstructed and issued at the ACS rate but with significantly reduced memory requirements. The ACS of the LRO is used as an example to illustrate the behavior of a practical ACS.
The relationship between social responsibility and public libraries accountability: The mediating role of professional ethics and conscientiousness
Authors: Soltani-Nejad Nima , Jahanshahi Marzieh , Karim Saberi Mohammad , Ansari Nasim , Zarei-Maram Nayereh
Published: May 2021

Public libraries are powerful social institutions whose services have a positive contribution to civil society. As one of the most important and most visited social institutions, such libraries are responsible to the community. Promoting social responsibility in public libraries requires addressing issues such as librarians’ accountability, professional ethics, and conscientiousness. Accordingly, this study strives to address this research gap by examining the relationship between organizational social responsibility and accountability perceived by staff in public libraries. Based on theoretical foundations, librarians’ professional ethics and conscientiousness were considered as mediating variables. Quantitative research method was used for this study and six hypothesized relationships were formulated to develop a conceptual model. Study data were collected through a questionnaire. Data obtained from 362 librarians of Iranian public libraries were analyzed running SPSS software and Smart PLS 3.0. The results revealed that perceived social responsibility of public libraries directly contributes to their perceived responsiveness. Furthermore, the implementation of social responsibility by public libraries reinforces the professional ethics and conscientiousness of librarians. As a result, the professional ethics and conscientiousness will lead to improving the accountability of public libraries. Accordingly, this study can help public library administrators, policymakers, and librarians to develop more comprehensive strategies for providing services to citizens by focusing on their social responsibilities, thereby establishing their place in society.
Inter-regional underemployment and the industrial reserve army: Precarity as a contemporary Greek drama
Authors: Herod Andrew , Gourzis Kostas , Gialis Stelios
Published: May 2021

We explore the 2008/2009 economic crisis in Greece and its impact upon employment precarity. Specifically, we focus upon changing regional patterns of waged part-timerism during three periods: the 2005–2008 pre-crisis period; the 2009–12 deep recession; and the 2013–2016 period of mild stabilization. Our analysis reveals important geographical and sectoral variations in the growth of this type of underemployment. In particular, we find that metropolitan regions have experienced the heaviest losses in full-time waged employment and a significant expansion of underemployment. Moreover, they have struggled to bounce back effectively during the period of stabilization. By way of contrast, island regions orientated towards tourism weathered the crisis to a much better degree, with many avoiding the acute flexibilization felt in more urbanized regions. Our study observes a “downwards convergence” of regional employment figures that is caused by Attica’s disproportionate crisis. This contrasts popular accounts that focus upon productive output. Moreover, by documenting distinct sectoral trajectories, such as the substantial flexibilization of tourism-related activities, we shed light upon the specifics of an industry often praised for its adaptiveness. Ultimately, through exploring the changing spatialities and sectoral specificities of growing flexibility during a period of recession and recovery, our study provides a geographically sensitive perspective on the emerging dynamics of the Greek reserve army of labour. In so doing, we further historical geographical materialist understandings of the capitalist crisis in Southern Europe.
Complex PTSD and personality disorder in ICD-11: when to assign one or two diagnoses?
Authors: Felding Simon Ungar , Mikkelsen Line Bang , Bach Bo
Published: May 2021

Objective:

To outline overlap and boundaries between ICD-11 definitions of complex post-traumatic stress disorder (C-PTSD) and personality disorder (PD) and propose guiding principles that may assist practitioners in assigning one or both of the two diagnoses.

Conclusions:

The ICD-11 definitions for C-PTSD and PD are substantially comparable in terms of self- and interpersonal problems, and childhood trauma may be at the root of both disorders. The ICD-11 formally recognizes this overlap and allows the assignment of both diagnoses at the same time. The C-PTSD diagnosis essentially differs from a PD diagnosis by requiring a history of trauma and PTSD symptoms. Moreover, C-PTSD typically involves stable and persistent patterns of negative self-perception while emphasizing avoidant interpersonal patterns. In comparison, the PD diagnosis may differ from C-PTSD by allowing an unstable or internally contradictory sense of self, which may involve both overly negative and overly positive self-views. When the diagnostic requirements for both C-PTSD and PD are met, only the C-PTSD diagnosis should be assigned, unless the PD diagnosis may contribute with clinically useful information that is not sufficiently covered by the C-PTSD diagnosis. The outlined similarities and boundaries must be further corroborated by future empirical studies.
Expert consensus on the operation of an adult tertiary intellectual disability mental health service in New South Wales, Australia
Authors: Walsh Jessica A , Weise Janelle , Eagleson Claire , Trollor Julian N , Cvejic Rachael C
Published: May 2021

Objective:

To identify and reach consensus on the priorities and operation of an adult tertiary intellectual disability mental health service in New South Wales, Australia.

Method:

An online Delphi consultation was conducted with 25 intellectual disability mental health experts.

Results:

Participants agreed that the service should involve a multidisciplinary team and accept people with an intellectual disability aged over 15 years with complex needs and/or atypical presentations. Agreed service roles included short-term assessment, diagnosis and treatment, providing high-level clinical advice, and capacity building. Endorsed principles and practical ways of working align with existing guidelines.

Conclusions:

This study describes experts’ views on how an adult tertiary intellectual disability mental health service should operate in New South Wales. Further consultation is needed to determine the views of people with an intellectual disability and mental health staff.