bluuebunny/crossref_metadata_2025 huggingface dataset:
Vertical Wind Effect on Slope and Shape Parameters of Gamma Drop Size Distribution
Authors: Chen Chao-Hsin , Su Ching-Lun , Chen Jui-Hsiang , Chu Yen-Hsyang
Published: February 2020

Approximate equations for slope Λ and shape μ parameters of the gamma raindrop size distribution (DSD) are derived from theoretical considerations on the basis of the reflectivity-weighted mean terminal velocity VT and Doppler spectral width σp of the raindrop echoes. These approximate equations are then corrected to reduce the error by using the long-term ground-based disdrometer measurements. We applied these equations on the VHF-radar measurements (i.e., reflectivity-weighted mean fall velocity and Doppler spectral width) to estimate μ and Λ aloft. The effects of the vertical wind velocity on the VHF radar-estimated μ–Λ and σp–VT values are investigated. The result shows that there is a tendency for the μ and Λ values to increase with an increase of the upward wind velocity. In addition, the terminal velocity and the spread of the DSD estimated from the precipitation echoes are strongly related to the vertical air velocity. The stronger the upward vertical air velocity is, the larger the terminal velocity and the smaller the spread of the DSD will be. The dependence of the estimated μ and Λ values on the vertical wind velocity is very likely caused by the updraft that can support and carry away the smaller raindrops in the original drop size distribution in the radar volume. Consequently, the DSDs aloft are truncated and the corresponding μ and Λ values estimated from the radar returns tend to be larger. To confirm this assertion, we intentionally truncate disdrometer-measured DSDs at small drop size end and calculate corresponding μ and Λ values. The results show that the distribution patterns of the μ–Λ scatter diagrams of the truncated DSDs bear strong resemblance to those of the radar observations, both of which are very different from those obtained on the ground.
Single-Precision in the Tangent-Linear and Adjoint Models of Incremental 4D-Var
Authors: Hatfield Sam , McRae Andrew , Palmer Tim , Düben Peter
Published: February 2020

The use of single-precision arithmetic in ECMWF’s forecasting model gave a 40% reduction in wall-clock time over double-precision, with no decrease in forecast quality. However, using reduced-precision in 4D-Var data assimilation is relatively unexplored and there are potential issues with using single-precision in the tangent-linear and adjoint models. Here, we present the results of reducing numerical precision in an incremental 4D-Var data assimilation scheme, with an underlying two-layer quasigeostrophic model. The minimizer used is the conjugate gradient method. We show how reducing precision increases the asymmetry between the tangent-linear and adjoint models. For ill-conditioned problems, this leads to a loss of orthogonality among the residuals of the conjugate gradient algorithm, which slows the convergence of the minimization procedure. However, we also show that a standard technique, reorthogonalization, eliminates these issues and therefore could allow the use of single-precision arithmetic. This work is carried out within ECMWF’s data assimilation framework, the Object Oriented Prediction System.
Transgender Status, Gender Identity, and Socioeconomic Outcomes in the United States
Authors: Carpenter Christopher S. , Eppink Samuel T. , Gonzales Gilbert
Published: February 2020

This article provides the first large-scale evidence on transgender status, gender identity, and socioeconomic outcomes in the United States, using representative data from 35 states in the Behavioral Risk Factor Surveillance System (BRFSS), which asked identical questions about transgender status and gender identity during at least one year from 2014 to 2017. More than 2,100 respondents, aged 18 to 64 years, identified as transgender. Individuals who identify as transgender are significantly less likely to be college educated and less likely to identify as heterosexual than are individuals who do not identify as transgender. Controlling for these and other observed characteristics, transgender individuals have significantly lower employment rates, lower household incomes, higher poverty rates, and worse self-rated health compared to otherwise similar men who are not transgender.
Emotional Intelligence and Strategies for Coping With Stress Among Music School Students in the Context of Visual Art and General Education Students
Authors: Nogaj Anna Antonina
Published: February 2020

This article addresses the psychosocial functioning of young people with artistic abilities. The study involved 354 students from music, art, and general education schools, ages 16 to 19 years. The research hypothesis was that the diversity of situations experienced by students studying at different types of schools could generate differences in their socio-emotional functioning, focusing on features such as emotional intelligence and coping strategies. The variables connected with emotional intelligence were acceptance, empathy, controlling, and understanding, and the variables connected with coping strategies were task-, emotion-, and avoidance-orientation. The results indicated that music students differed significantly from art students in the level of their emotional intelligence in general results and on the Acceptance scale; they are more aware of the positive and negative emotions that they feel, express their emotions more easily, and can effectively use their knowledge about the emotions they experience. Moreover, in stressful situations, music students exhibit task-oriented coping strategies significantly more often and are significantly less likely to engage in substitute actions than are art students.
The effects of textile reinforcements on the protective properties of self-healing polymers intended for safety gloves
Authors: Irzmańska Emilia , Bacciarelli-Ulacha Anna , Adamus-Włodarczyk Agnieszka , Strąkowska Anna
Published: February 2020

In the environment where glove material is exposed to harmful chemicals, hazards related to faster penetration of dangerous substances into the glove interior may cause microdamage. One of the solutions to overcome this problem is to use the self-healing polymeric materials that can minimize economic loss and accidents in the workplace.

The current work aims to present the impact of different types of textile reinforcement on the effectiveness and efficiency of the self-healing process of methyl vinyl silicone rubber containing hybrid molecules with an inorganic silsesquioxane intended for use on all-rubber gloves. Three knitted fabrics with a similar structure and differentiated raw material composition were selected: polyamide, cotton–polyamide, and cotton.

Evaluation of the self-healing process of the elastomeric composite to personal protective equipment was performed. For this purpose the assessment of the surface morphology of materials has been performed before and after the self-healing process.

The implementation of knitted fabric into the polymeric composite in the tested samples allowed us to obtain the best results in all tests. The studied composite samples exhibited an increased resistance to three types of damage: penetration, abrasion and puncture. The samples also underwent the self-healing processes and regeneration after a proper conditioning period. Thus, the obtained results confirmed the possibility of using tested elastomeric composites in the construction of protective gloves and showed an effectivity of the self-healing process for the long-term usage of that protective equipment.
Neighbourhood effects on acculturation attitudes among minority and majority adolescents in Germany
Authors: Kretschmer David , Kruse Hanno
Published: February 2020

Attitudes on whether immigrants should culturally adapt to their receiving society or maintain the customs of their origin context vary – not only between majority and minority populations but also within these groups. Focusing on adolescents in the German context, this study investigates whether such acculturation attitudes are shaped by the ethnic composition of a person’s neighbourhood context. Building on arguments from theories of intergroup contact, concentration effects and reactive ethnicity, we expect different effects for minority and majority adolescents. To empirically investigate these expectations, we combine survey data on N = 4621 adolescents and their parents with geocoded information on the characteristics of their neighbourhood contexts. Exploiting an intergenerational set-up to account for neighbourhood selection, we find indication of neighbourhood effects among minority adolescents. Among majority youth, acculturation attitudes turn out to be unrelated to neighbourhood ethnic composition.
A new operational matrix based on Boubaker wavelet for solving optimal control problems of arbitrary order
Authors: Rabiei Kobra , Ordokhani Yadollah
Published: February 2020

This paper presents numerical solution for solving the nonlinear one and two-dimensional optimal control problems of arbitrary order. First, we have constructed Boubaker wavelet for the first time and defined a general formulation for its fractional derivative operational matrix. To solve the one-dimensional problem, we have transformed the problems into an optimization one. The similar process together with the Ritz method are applied to find a solution for two-dimensional problems as well. Then, the necessary conditions of optimality result in a system of algebraic equations with unknown coefficients and then control parameters can be simply solved. The error vector is considered to show the convergence of the used approximation in this method. Finally, some illustrative examples are given to demonstrate accuracy and efficiency of the proposed method.
“The Way You Enter a Church”: The Dialectics of Ken Burns’s Baseball
Authors: Jenemann David
Published: February 2020

Taken as a whole, Ken Burns’s 1994 documentary Baseball and its 2010 follow-up The Tenth Inning stand as some of the most influential documentaries on the history of American sports. Baseball develops the link between the “fun” of the game and philosophical beliefs about American democracy through a “dialectical aesthetic” that operates through Baseball’s choice of subjects and historical events as well as through its formal documentary strategies. While many critics dismiss Baseball as overly nostalgic, this essay argues that Baseball engages the reader with the dialectic to encourage self-reflection about the future of the game and its role in civil society.
Manifestation of stress and anxiety in the stomatognathic system of undergraduate dentistry students
Authors: Owczarek Joanna Elżbieta , Lion Katarzyna Małgorzata , Radwan-Oczko Małgorzata
Published: February 2020

Objective

To assess the relationship between psychoemotional state and signs of oral cavity occlusal and nonocclusal parafunctions, together with masseter muscle tone, in undergraduate dentistry students.

Methods

The study population comprised first and fifth grade dentistry students who were investigated using psychological and health questionnaires, and stomatological examination with electromyography of the masseter muscles. Differences in variables between first and fifth grade students were analysed using Student’s t-test or χ2-test and Pearson’s correlation coefficient was used to analyse associations between variables.

Results

A total of 113 students (52 first-grade, mean age 20 years; and 61 fifth-grade, mean age 23.6 years) were included. Older age was associated with lower level of perceived stress and anxiety. Moreover, a significant positive relationship was observed between level of perceived stress and anxiety and tone of both masseter muscles.

Conclusions

Increased psychoemotional burden and increased rates of experienced anxiety were associated with growth of masseter muscle tone in this study population.
Multicentric Castleman’s disease in a renal allograft recipient: a case report and literature review
Authors: Lin Jinwen , Yu Shiping , Wang Rending , Chen Jianghua
Published: February 2020

Giant lymph node hyperplasia is the main symptom of Castleman’s disease (CD), which is a rare and easily overlooked lymphoproliferative disease that mimics both benign and malignant lesions. Several cases of CD after renal transplantation have been reported in the literature. A 43-year-old man was admitted to our medical center with high serum globulin levels after receiving a living donor kidney transplant. A lymph node biopsy raised suspicion for multicentric CD. Because of the poor therapeutic effect of reduction of immunosuppression, the patient was treated with CHOP chemotherapy comprising four cycles of monthly cyclophosphamide (750 g/m2, day 1), vincristine (1.4 g/m2, day 1), doxorubicin (50 g/m2, day 1), and prednisone (60 mg/m2, daily). Following the treatment, his serum globulin levels decreased to the normal range. At the 2-year follow-up examination, the abdominal, axillary, and inguinal lymph nodes had significantly decreased in size. Without a pathological diagnosis, multicentric CD after renal transplantation can be easily ignored and misdiagnosed. If the clinical signs cannot be relieved by minimizing the dose of common immunosuppressants, the CHOP regimen may be a better option. Biological agents may be added in patients with positive immunohistochemistry staining and good economic conditions.
Intracranial Epstein–Barr virus infection appearing as an unusual case of meningitis in an immunocompetent woman: a case report
Authors: Wang Yue , Dong Qian , Chen Yu-dan , Hu Wen-li , Zhao Li
Published: February 2020

Epstein–Barr virus (EBV) is a member of the herpesvirus family, which infects most of the world’s population. EBV infection usually occurs asymptomatically. However, there are subsets of the population, such as juveniles and immunocompromised patients, among whom EBV may manifest symptomatically. In some cases, symptomatology involves the central nervous system. One such manifestation of EBV is meningitis. We report a unique case of EBV infectious meningitis in an immunocompetent adult female patient who showed unconventional clinical features. These features included afternoon fever, high intracranial pressure, low cerebrospinal fluid glucose levels, and an absence of blood monocytosis. Because this case involved a unique symptomatology, our findings broaden the symptom profile of EBV infection as presently understood.
Osteoid osteoma: lower back pain combined with scoliosis
Authors: Chen Yun-lin , Jiang Wei-yu , Ma Wei-hu
Published: February 2020

Osteoid osteoma is a small benign bone tumor that is primarily localized in long bone; lumbar osteoid osteoma combined with scoliosis has rarely been reported. Here, we describe a 9-year-old boy who complained of back pain and scoliosis. He underwent nidus resection and did not experience complications or osteoid osteoma recurrence. His pain and scoliosis were relieved after the operation. The findings in this case indicate that resection of osteoid osteoma is an effective and safe method of treatment. The lumbar spine is the most common location of osteoid osteoma, which causes painful scoliosis. Nidus resection can provide relief of back pain and scoliosis.
A practical nonlinear damage accumulation method to predict the life and crack propagation of blade subjected to multilevel cyclic fatigue loads
Authors: Gao Tianrun , Jing Jianping , Chen Changmin , Cong Jiqing , Li Jianzhao , Cao Shiyu
Published: February 2020

An accurate life prediction is important to the design of a high-speed rotary blade subjected to multilevel cyclic loads. The widely used Miner’s rule and uniaxial stress prediction method always deviate from actual life of the blade. A prediction method based on Chaboche’s nonlinear damage evolution model is utilized to predict the multilevel cyclic fatigue life of a compressor blade subjected to start-up centrifugal force and working aerodynamic force. Chaboche’s model is verified by comparing with experimental data of different materials. The blade life predicted by Chaboche’s rule and Miner’s rule are compared, and it is found that Miner’s rule might overestimate the blade life under the typical loading spectrum of start-up centrifugal force and working aerodynamic force. To study the impact of multiaxial stress state on the blade life, the life predicted by uniaxial stress method is compared to that predicted by multiaxial stress method, and it demonstrates that the multiaxial stress state of the blade should not be neglected. Finally, the crack propagation of the blade under multiaxial fatigue loads is simulated successfully by element deletion technique, which is conducted by translating Chaboche’s multiaxial model into a user defined UMAT program in ABAQUS. The predicted crack propagation life is compared with that predicted by an approximate Paris law method plate model. This research proves that the method to predict the blade life subjected to multilevel cyclic loads based on multiaxial Chaboche’s model could provide a valuable reference for engineering blade fatigue design.
Online Mapping Platforms: Between Citizen-Oriented and Research-Focused Tools of Participation?
Authors: Kotus Jacek , Rzeszewski Michał
Published: February 2020

Contemporary planning debate goes beyond the issues of material placemaking. It has been proposed that Public Participation Geographical Information System (PPGIS) methods (mapping platforms in particular) can help to achieve civic maturity, sense of agency, and the social development of the inhabitants. However, researchers need to be consciously engaged (e.g., embracing a Participatory Action Research [PAR] approach), to really pass those platforms to the hands of the community and help the inhabitants to form a two-way communication. With the right use, mapping platforms can be more than just a simple data collection tool. Used without deeper awareness, it can only remain a modern tool.
Engaging From Both Sides: Facilitating a Canadian Two-Generation Prenatal-to-Three Program for Families Experiencing Vulnerability
Authors: Ginn Carla , Mughal Muhammad K. , Pruett Marsha K. , Pruett Kyle , Perry Robert L. , Benzies Karen
Published: February 2020

Background

Young children living in families experiencing social vulnerability, including low income, mental illness, addictions, social isolation, and/or homelessness, are at risk of developmental delay. Two-generation programs can improve outcomes for preschool children, but underlying mechanisms and outcomes for younger children remain unclear.

Purpose

We explored program facilitation and identified developmental benefits of a two-generation program beginning prenatally.

Methods

In our convergent, concurrent mixed methods study, we interviewed agency staff ( n =  10) and held focus groups with parents ( n =  14). We compared child ( N =  100) development between program intake and exit as measured by the Ages and Stages Questionnaires 3rd edition.

Results

Our core category, Engaging From Both Sides, included (a) Mitigating Adversity (focused codes Developing Trust, Letting Go of Fear, and Putting in the Effort); (b) Continual Learning (focused codes Staying Connected, and Taking it to the Community); (c) Fostering Families (focused codes Cultivating Optimism, and Happiness and Love); (d) Unravelling Cycles of Crisis (focused codes Advocating, and Helping Parents’ Parent); and (e) Becoming Mainstream (focused codes Knowing Someone Has Your Back, and Managing Stress, Anxiety, and Anger). We found significant improvements in child Fine Motor, Problem-Solving, and Personal-Social domains between program intake and exit.

Conclusions

Our study adds to existing literature regarding mechanisms of two-generation programs beginning prenatally. Mitigating effects of intergenerational adversity was the primary motivation for interaction and engagement of staff and parents in two-generation programming, which improved child development.
Galactose-functionalized GlycoAuNR as a photothermal conversion complex: Its binding to lectin RCA120 and hepatoma-targeting therapy
Authors: Zheng Yongli , Zhang Yina , Wu Hua , Shao Dongjie , Shen Fawei , Cai Hao , Quan Jing
Published: February 2020

Glycopolymer-grafted gold nanorods (GlycoAuNRs) were designed and fabricated as a heptoma-targeting phototherapy nanoparticles. The block glycopolymer, poly (diethyleneglycol methacrylate)-block-poly(6-O-vinyladipoyl-α-D-galactose) (PDEGMA-b-POVNGA), was synthesized by RAFT polymerization and modified AuNRs with Au-S bonds via reducing the thioester at the end of glycopolymer to thiol (–SH). Galactose pendants of thermosensitive AuNRs@PDEGMA-b-POVNGA were exposed when the temperature of aqueous dispersion is above lower critical solution temperature, which was responsible for specific binding ability with ricinus communis agglutinin. In vitro experiment indicated that the synthesized glycopolymer could significantly improve cytocompatibility of AuNRs and target to hepatocellular carcinoma cells, owing to the galactose moiety that recognized the overexpressed asialoglycoprotein receptor on the hepatocellular carcinoma cells. Interestingly, the addition of ricinus communis agglutinin could inhibit the growth of the hepatocellular carcinoma cells in some extent. Furthermore, the photothermal therapy assay proved that glycoAuNRs-ricinus communis agglutinin could realize highly effective photothermal treatment for the tumor cells in vitro upon laser irradiation by cooperative effect.
Does Adherence to Mediterranean Diet Mediate the Association Between Food Environment and Obesity Among Non-Hispanic Black and White Older US Adults? A Path Analysis
Authors: Chen Meifang , Howard Virginia , Harrington Kathy F. , Creger Thomas , Judd Suzanne E. , Fontaine Kevin R.
Published: February 2020

Purpose:

This study aims to test the hypothesis that in addition to a direct effect of food environment on obesity, food environment is indirectly associated with obesity through consuming Mediterranean diet (MD).

Design:

Cross-sectional secondary data analysis.

Setting:

Nationwide community-dwelling residency.

Sample:

A total of 20 897 non-Hispanic black and white adults aged ≥45 years who participated in the REasons for Geographic and Racial Differences in Stroke study and completed baseline assessment during January 2003 and October 2007.

Measures:

The Modified Retail Food Environment Index (mRFEI; 0-100) was used as food environment indicator. The MD score (0-9) was calculated to indicate the dietary pattern adherence. Body mass index (BMI; kg/m2) was used to estimate obesity.

Analysis:

Path analysis was used to quantify the pathways between food environment, MD adherence, and obesity. Proper data transformation was made using Box–Cox power transformation to meet certain analysis assumptions.

Results:

The participants were from 49 states of the United States, with the majority (64.42%) residing in the South. Most of the participants were retired, female, white, married, having less than college graduate education, having annual household income ≤75 000, and having health insurance. The means of mRFEI was 10.92 (standard deviation [SD] = 10.19), MD score was 4.36 (SD = 1.70), and the BMI was 28.96 kg/m2 (SD = 5.90). Access to healthy food outlets (β = .04, P < .0001) and MD adherence (β = .08, P < .0001) had significant and inverse relationships with BMI, respectively. Mediterranean diet adherence mediated the relationship between food environment and obesity among a subpopulation who had an annual household income of <$75 000 (β = −.02, P = .0391).

Conclusion:

Population-tailored interventions/policies to modify food environment and promote MD consumption are needed in order to combat the obesity crisis in the United States.
When Relationships Meet Situations: Exploring the Antecedents of Employee Communication Behaviors on Social Media
Authors: Wang Yuan
Published: February 2020

Grounded in the relationship management theory and the situational theory of publics, this study examines the effects of employees’ perceived relationships with their organization on their situational perceptions and how these perceptions influence their communication behaviors on social media. An integrated model of situational organization–employee relationship is proposed and tested. The study was based on a national survey of 449 employees working at large organizations in the United States. Organization–employee relationships were found to facilitate employees’ problem recognition and level of involvement and to weaken their constraint recognition. Employees with low constraint recognition and high levels of involvement were more likely to seek, process, and share information on social media, whereas those with high problem recognition tended only to process information. This study is one of the first to integrate the relational perspective with the situational perspective. It also offers practical suggestions for large organizations on how to build and maintain quality relationships with employees and improve their communication behaviors on social media.
Clinical relevance of marginal factors on ultrafiltration in peritoneal dialysis
Authors: Pérez-Díaz Vicente , Pérez-Escudero Alfonso , Sanz-Ballesteros Sandra , Sánchez-García Luisa , Hernández-García Esther , Oviedo-Gómez Victoria , Sobrino-Pérez Alicia
Published: February 2020

Background:

Ultrafiltration (UF) in peritoneal dialysis (PD) is mainly driven by the osmotic gradient and peritoneal permeability, but other factors—such as intraperitoneal pressure (IPP)—also have an influence.

Methods:

To assess the clinical relevance of these marginal factors, we studied 41 unselected PD patients undergoing two consecutive 2 h, 2.27% glucose exchanges, first with 2.5 L and then with 1.5 L.

Results:

IPP, higher in the 2.5 L exchange, had a wide interpatient range, was higher in obese and polycystic patients and their increase with infusion volume was higher for women regardless of body size. UF with 2.5 L correlated inversely with IPP and was higher for patients with polycystosis or hernias, while for 1.5 L we found no significant correlations. The effluent had higher glucose and osmolarity in the 2.5 L exchange than in the 1.5 L one, similar for both sexes. In spite of this stronger osmotic gradient, only 21 patients had more UF in the 2.5 L exchange, with differences up to 240 mL. The other 20 patients had more UF in the 1.5 L exchange, with stronger differences (up to 800 mL, and more than 240 mL for 9 patients). The second group, with similar effluent osmolarity and peritoneal equilibration test (PET) parameters than the first, has higher IPP and preponderance of men. The sex influence is so intense that men decreased average UF with 2.5 L with respect to 1.5 L, while women increased it.

Conclusions:

With 2.27% glucose, sex and IPP—modulated by obesity, polycystosis, hernias, and intraperitoneal volume—significantly affect UF in clinical settings and might be useful for its management.
A decentred assessment of the impact of ‘informal governance’ on democratic legitimacy
Authors: Ayres Sarah
Published: February 2020

The aim of this article is to examine the impact of informal governance on democratic legitimacy. It draws on the literatures on informal governance and decentred theory to examine how governance mechanisms that are un-written, un-codified and non-institutional impact on democratic legitimacy in governance networks. Drawing on a case study of English devolution in the United Kingdom, this article explores how informal governance impacts on different dimensions of legitimacy – input, throughout and output. It does so by drawing on the narratives and stories of central government officials directly involved in English devolution between 2015 and 2018. Findings reveal that even when formal structures are weak, democratic legitimacy can be secured, especially in promoting effective decision making and problem solving – throughput legitimacy. Nonetheless, a decentred analysis has shown a high level of selectivity and differentiation in central-local relationships that undermine legitimation based on input (inclusiveness) and outcome (results) legitimacy. This assessment provides important new insights into how governance networks characterized by high levels of informality can promote democratic legitimacy in ways that reflect the nuances of political decision making in highly complex environments. The challenge for politicians and policy makers moving forward is to actively manage the inevitable trade-offs generated through the use of informality if accusations of a democratic deficit are to be averted.
Comparing user and community co-production approaches in local ‘welfare’ and ‘law and order’ services: Does the governance mode matter?
Authors: Loeffler Elke , Timm-Arnold Peter
Published: February 2020

This paper analyses the relationship between modes of governance at local level and the adoption of user and community co-production approaches in community safety and social care services, based on a German case study. The findings draw on a series of intensive focus groups with managers and staff of public services in four different regions in Germany, exploring existing levels of co-production and its potential in social care and community safety services, with particular focus on older and young people. The paper provides the first clear research evidence on how approaches to co-production are specific to the modes of governance within which they take place. The paper concludes with policy conclusions, both in the two programme areas concerned and in local public services more generally.
Mechanical behavior of polyimide filament tows under high strain rate tension
Authors: Wang Boyao , Zhang Mengying , Han Enlin , Tian Guofeng , Wang Guanghua , Wu Dezhen
Published: February 2020

The tensile properties of polyimide (PI) filament tows were measured under quasi-static state and at high strain rates with a universal tensile testing machine and a split Hopkinson tension bar, respectively. Experimental results showed that mechanical behaviors of the tows were rather sensitive to strain rate, with failure stress and modulus increasing distinctly but the elongation at break declining as the strain rate increased. Besides, the PI filament tows exhibited a higher growth rate of fracture stress than para-aramid fiber and aramid III fiber did, and scanning electronic microscopy observation on the fracture surface indicated a ductile fracture mode. With the increase of strain rate, the axial splitting of fiber intensified. Further, strength distributions of the PI filament tows were evaluated by a single Weibull distribution function, and the curve predicted was in good accordance with the experimental data obtained.
Analysis of coupled motion constraints and coupling errors for a six-axis magnetic levitation stage
Authors: Sheng Xiaochao , Menq Chia-Hsiang , Tao Tao
Published: February 2020

This paper presents the coupled motion constraints and coupling errors analysis of a magnetic levitation stage, which are two aspects of the coupling characteristics of magnetic levitation stage caused by force coupling. Aiming at the motion constraint coupling problem, this paper proposes a motion constrain method based on the force distribution matrix of the magnetic levitation stage. By this method, the motion constraint intervals without input saturation for single-degree-of-freedom motion, in-plane motion, and out-of-plane motion of magnetic levitation stage are established. When used for motion control, these constraints can provide the motion constraint specifications for the magnetic levitation stage, avoid the input saturation problem caused by the actuation force coupling, and provide a theoretical basis for magnetic levitation stage trajectory planning. Aiming at reducing the coupling error, this paper proposes a strategy to evaluate the coupling degree of the magnetic levitation stage actuation force by the condition number of the actuation force transfer matrix and the singular value of the force and torque error matrix. On this basis, the force and torque coupling errors caused by the translational and rotational movements of the magnetic levitation stage are studied, and the mechanism and characteristics of the coupling error between the interaction of translational and rotational movements are revealed. Based on the obtained results, the decoupling algorithm of the magnetic levitation stage is designed. Experimental results of the normalized step response demonstrate that the linearity of the magnetic levitation stage will be destroyed by the current saturation, and coupling error can also be introduced. Therefore, it is necessary to study the motion constrain strategy to provide comprehensive criteria for the trajectory planning and controller design. Experimental results of six-axis coupling error analysis show that the coupling error of x- and y-axes translational movement is reduced by 69.34% and 69.60%, respectively. This method provides a theoretical basis for the decoupling of the magnetic levitation stage and reducing the coupling error.
Establishment of micropit diameter prediction models based on the support vector machine optimization
Authors: Tong Xin , Yu Song , Wang Lihui
Published: February 2020

Many studies on microtextures have focused on the effect of laser processing parameters on microtextured morphology from the experimental point of view, and not on its influence on the physical field and stress field around the microtextures. This has resulted in the lack of accurate predictions on micropit diameters, thus reducing the processing efficiency. In order to address these problems, the effects of laser processing parameters on the precision machining, physical field, and stress field of micropit textures for a ball-end milling cutter were studied by experiments and simulation. The optimum laser processing parameters include laser power of 70%, scanning speed of 1700 mm/s, and scanning of seven times. Based on the optimized data of a support vector machine, the prediction models of micropit diameters for laser machining were established. The errors of the models are less than 10%, thus verifying their accuracy. This study can serve as a theoretical reference for the efficient processing of titanium alloys.
A data-driven predictive controller combined with the vector autoregressive with exogenous input model and the propagator estimation method for vehicle lateral stabilization
Authors: Deng Weishun , Yang Weimiao , Zhang Jianwu , Feng Pengpeng , Yu Fan
Published: February 2020

A general predictive controller based on the subspace model identification method is proposed for vehicle stabilization. Traditional predictive controllers are always developed based on the principle model of vehicles, which inevitably suffers from parameter uncertainty and poor adaptability. In contrast to that, the proposed subspace-based general predictive controller is realized by a data-driven process and presents good adaptability in vehicle stability control. Inspired by subspace-based predictor construction, the keys of the predictive controller are as follows: (1) system model identification according to the model structure of the control object by input and output data; (2) output prediction of the system by the identified model; and (3) optimal control law designed by combining the linear–quadratic–Gaussian index with the predictive output. The main problem in the controller development lies in the recursive estimation of relevant matrices, which is limited by the subspace model identification theory. The implementation of the vector autoregressive with exogenous input model and the propagator method in subspace identification algorithm effectively solves the problem of estimation accuracy and calculation efficiency. Combined with a linear–quadratic–Gaussian index function, the predictive law for vehicle stability control is derived in detail. Finally, based on the vehicle model validated by standard road test, the effectiveness and robustness of the predictive controller are proved through the numerical simulations of various maneuvers under different road adhesive conditions.
Development of multi-motor synchronous control system based on network-on-chip
Authors: Feng Xiangli , Zhuo Qingqi , Liu Xiubin , Qian Yanlin , Li Yue
Published: February 2020

This article presents a novel system architecture based on network-on-chip for multi-motor synchronous control. The system integrates several servo motor controllers in a single chip which permits an increase to the number of motors according to the application requirements. Compared with traditional multi-motor control architectures, such as bus-based distributed architecture and single-core microprocessor architecture, network-on-chip-based architecture supports high-precision multi-axis real-time control with high network bandwidth and parallel processing. A four-wheel drive intelligent car experiment platform is developed for performance testing. It has a convenient process for parameter tuning. Several experiments are conducted to demonstrate the feasibility and real-time performances of the system. The research work has a good potential in integration, real-time performance of multi-motor synchronous control system.
Ontologically dirty knots: The production of numbers after the Srebrenica genocide
Authors: Toom Victor
Published: February 2020

Approximately 8,000 boys and men were killed in the 1995 Srebrenica genocide. The victims were disappeared, killed and buried in secret mass graves. In this article, I examine how forensic anthropologists, demographers and forensic geneticists produced technolegal knowledge about the number of victims in the wake of the genocide; how those numbers were validated in legal proceedings against those held responsible; and, finally, how some have tried to destabilize the numbers in attempts to deny that a genocide was committed. While numbers, and the larger category of knowledge, take centre stage in the discussion, I use Srebrenica’s aftermath to introduce the concept of ontologically dirty knots, which is an analytical and methodological innovation that enables us to produce scholarly accounts of events, such as the Srebrenica genocide, that are characterized partly by secrecy, partly by controversy and partly by materiality. It ties together meaning and materiality, signals a process that continues to evolve, and suggests that narratives about what happened are the results of entanglements, action and friction that can be undone. In these respects, the article addresses current discussions on actor-network theory within critical security studies.
‘Apprenticeship’ in the Italian approach to the dual system
Authors: Rustico Lisa , David Ramona , Ranieri Antonio
Published: February 2020

Since 2003, Italy’s legislation on apprenticeships has regulated a scheme under which candidates can obtain upper- and post-secondary-level qualifications – type 1 apprenticeship – that share features with the dual system of vocational education and training (VET) to be found in German-speaking countries. This scheme has never been extensively implemented, not even in the wake of its latest reform in 2015, which made the scheme part of what might be termed the ‘Italian dual system’. The Cedefop review of type 1 apprenticeship identifies several challenges related to features of the scheme’s governance and design that still hamper its full implementation. In a European perspective, these challenges are common to an emerging approach to apprenticeship, characterised by a lack of clarity about its purpose and place within the education and training system. This may cast a shadow over the educational function of apprenticeships, especially as EU policy is to strengthen their educational value by linking them to schooling and formal qualifications.
The German system of vocational education and training: challenges of gender, academisation and the integration of low-achieving youth
Authors: Haasler Simone R
Published: February 2020

In Germany, the dual system of apprenticeship training has traditionally been very strong. The dominant position of the dual system, however, is being challenged by other training routes gaining significance, particularly tertiary education. This article investigates the extent to which this is leading to a restructuring of the dual system. Developments in school-based vocational programmes, trends of academisation and challenges deriving from qualifying low achievers are discussed. The growing significance of school-based programmes is linked to the gender impact of the vocational education and training (VET) system and the gender segmentation of the German labour market, while academisation reflects labour market demands for high skills. With dual study programmes and three and a half-year dual training, the dual system seeks to provide attractive training options for highly skilled young people. This, however, has made access to fully-qualifying vocational programmes very difficult for low-achieving young people, including migrants and refugees, thereby challenging the integration function of the German VET system.
Dual training in Europe: a policy fad or a policy turn?
Authors: Šćepanović Vera , Martín Artiles Antonio
Published: February 2020

Since the start of the global financial crisis Europe has experienced a new enthusiasm for dual vocational education and training (VET). The EU itself has actively promoted the benefits of dual VET to its members, offering financial and organisational support for the introduction of apprenticeships into the formal educational systems. However, while dual VET is widely considered to be a valuable tool for easing the transition into the labour market for young people, it is also a form of skill formation that requires a lot of coordination not only between the schools and firms that carry out the training, but also among the firms themselves and between employer and employee organisations. In this introduction we argue that whereas the EU has been successful in encouraging establishment of dual VET in all its member countries, its implementation has been very uneven. This is due in part to the pre-existing differences in the underlying organisational structures, but also to the ongoing demographic, technological, and institutional changes – some caused by European integration itself – which weaken firms’ incentives to train.
Exercising associational and networked power through the use of digital technology by workers in global value chains
Authors: Helmerich Nicole , Raj-Reichert Gale , Zajak Sabrina
Published: February 2020

While there are heated debates about how digitalization affects production, management and consumption in the context of global value chains, less attention is paid to how workers use digital technologies to organize and formulate demands and hence exercise power. This paper explores how workers in supplier factories in global value chains use different digital tools to exercise and enhance their power resources to improve working conditions. Combining the global value chain framework and concepts from labour sociology on worker power, the paper uses examples from the garment industry in Honduras and the footwear industry in China to show how workers used old and new digital tools to create and enhance associational and networked powers. Digital tools were used by workers and their allies in the global value chain to lower costs of communication, increase information exchange and participate in transnational campaigns during labour struggles vis-à-vis firms and governments in structurally and politically repressive environments. The paper contributes to our understanding of how workers use of digital technologies to exercise and combine different resources of power in online and offline actions in global value chains, as well as how they are confronted by new dimensions of constrains which include digital surveillance and control by the state.
Entry of Providers Onto a Sharing Economy Platform: Macro-Level Factors and Social Interaction
Authors: Gerwe Oksana , Silva Rosario , Castro Julio de
Published: February 2020

Despite the recent proliferation of sharing economy platforms, little is known about what drives providers (individual people who own assets) to enter onto a sharing economy platform. The platform does not own the assets that underlie transactions but depends on individuals to provide them. In the burgeoning market of home rental properties, we investigate the role of macro-level factors to explain geographical differences in the number of entries of providers with diverse motivations onto a sharing economy platform. Using a sample of listings posted by property owners on the Airbnb platform across different cities in Spain between 2010 and 2015, we examine how social and economic motivations of providers interact with macro-level antecedents to affect their entry. We show that macro-level drivers have a different effect on the entry of providers depending on the degree of face-to-face interaction between host and guest. We find that industry growth and the availability of underused assets increase the entry onto the platform of hosts who have little face-to-face interaction with guests, while the strictness of regulation decreases their entry. By contrast, the entry of hosts with high face-to-face interaction with guests is not affected by these factors. We discuss theoretical and research implications of the role of social interaction in provider entry and offer practical advice for those in the sharing economy about the role of social interaction in driving providers onto their platforms.
Traditional Japanese Music in Contemporary Times
Authors: Howard Karen
Published: February 2020

Music in Japan is richly varied and includes documented genres dating back more than 1000 years. From classical court music known as gagaku, to the dramatic music plays in kabuki, to contemporary J-pop (subgenre of popular music), educators can find a sound to suit every instructional need. The focus here will be on considerations of three traditional instruments used in Japan: the koto (zither), shakuhachi (bamboo flute), and shamisen (three-stringed instrument), and a unique educational experience for those interested in studying these traditions. The learning program is offered through a koto school in Tokyo that is more than a century old, and they now offer a course in English every other summer. Also offered are suggestions for incorporating traditional Japanese music into elementary and secondary general music settings.
Results of an Evaluation of Therapeutic Residential Groups for Adolescents in Berlin
Authors: Wesenberg Sandra , Frank Christina , de Andrade Marilena , Weber Miriam , Rosemeier Claus-Peter , Krause-Lanius Bert , Gahleitner Silke B.
Published: February 2020

In the last few years, a large amount of research have been done in the field of youth care services. However, there is still a substantial need for empirical findings, especially on institutions with specific missions such as therapeutic residential groups for young people. This article grew out of cooperation between practitioners and researchers and presents the results of a German study entitled “Process Evaluation of Therapeutic Residential Groups for Young People” (TRGs). The main research question of the evaluation study was whether the treatment in the TRGs is specifically stabilizing, protective, and, above all, effective in dealing with young people with severe problems. The study employs multiple methodologies (qualitative and quantitative procedures) to obtain a satisfactorily comprehensive analysis of both outcome and process quality. The article presents selected results from the quantitative part of the study and the qualitative interview study and discusses them considering recent research in the field of child and adolescent care services.