bluuebunny/crossref_metadata_2025 huggingface dataset:
Histone demethylase JHDM2A participates in the repair of arsenic-induced DNA damage in L-02 cells by regulating DDB2
Authors: Li Changzhe , Zhang Anliu , Hu Ting , Yang Yue , Tang Shunfang , Li Jun
Published: May 2022

Arsenic is widely present in nature and is a class I carcinogen confirmed by the World Health Organization and the International Agency for Research on Cancer. The liver is responsible for biotransformation in the body and is one of the major organs where arsenic accumulates in the body, but the mechanisms of arsenic-induced abnormal DNA damage repair pathways in the liver are still unclear. Recent studies have revealed that epigenetic mechanisms play an important role in arsenic-induced lesions. In this study, an in vitro model was established using human normal hepatocytes L-02 to investigate the mechanism of the specific demethylase JHDM2A of H3K9me2 in the repair of arsenic-induced DNA damage in L-02 cells. The results showed that with the increase of arsenic concentrations, the extent of DNA damage in L-02 cells showed an increasing trend and total intracellular H3K9me2 expression was downregulated. In addition, the enrichment level of H3K9me2 in the promoter region of DBB2, a key factor of nucleotide repair (NBR), increased, while protein and mRNA expression levels showed a decreasing trend. Thereafter, we overexpressed and repressed JHDM2A and found a close association between JHDM2A and arsenic-induced DNA damage. DDB2 protein and mRNA expression was downregulated with JHDM2A overexpression and upregulated with JHDM2A repression, while DBB2 promoter region H3K9me2 enrichment levels remained at a high level, although they were affected after JHDM2A overexpression or knockdown to some extent. These results suggest a potential mechanism by which JHDM2A may regulate DDB2 gene expression, participate in the NBR process, and play a role in arsenic-induced DNA damage in L-02 cells, which is not the result of JHDM2A exerting demethylation on H3K9me2 in the DDB2 promoter region. Our results provided an epigenetic mechanism for endemic arsenicosis, as well as a scientific basis for potential prevention and control measures.
Priority Nursing Populations for Mental Health Support Before and During COVID-19: A Survey Study of Individual and Workplace Characteristics
Authors: Havaei Farinaz , MacPhee Maura , Ma Andy , Mao Yue
Published: May 2022

Background

Nursing is a high-risk profession and nurses’ exposure to workplace risk factors such as heavy workloads and inadequate staffing is well documented. The COVID-19 pandemic has exacerbated nurses’ exposure to workplace risk factors, further deteriorating their mental health. Therefore, it is both timely and important to determine nursing groups in greatest need of mental health interventions and supports.

Purpose

The purpose of this study is to provide a granular examination of the differences in nurse mental health across nurse demographic and workplace characteristics before and after COVID-19 was declared a pandemic.

Methods

This secondary analysis used survey data from two cross-sectional studies with samples (Time 1 study, 5,512 nurses; Time 2, 4,523) recruited from the nursing membership (∼48,000) of the British Columbia nurses’ union. Data was analyzed at each timepoint using descriptive statistics and ordinal logistic regression.

Results

Several demographic and workplace characteristics were found to predict significant differences in the number of positive screenings on measures of poor mental health. Most importantly, in both survey times younger age was a strong predictor of worse mental health, as was full-time employment. Nurse workplace health authority was also a significant predictor of worse mental health.

Conclusions

Structural and psychological strategies must be in place, proactively and preventively, to buffer nurses against workplace challenges that are likely to increase during the COVID-19 crisis.
A printability study of multichannel nerve guidance conduits using projection-based three-dimensional printing
Authors: Li Haibing , Yu Kang , Zhang Peng , Ye Yensong , Shu Qiang
Published: May 2022

Multichannel nerve guidance conduits (NGCs) replicating the native architecture of peripheral nerves have emerged as promising alternatives to autologous nerve grafts. However, manufacturing multichannel NGCs is challenging in terms of desired structural stability and resolution. In this study, we systematically investigated the effects of photopolymer properties, inner diameter dimensions, printing parameters, and different conditions on multichannel NGCs printability using projection-based three-dimensional printing. Low viscosity and rapid photocuring properties were essential requirements. A standard model was generated to evaluate multichannel NGC printed quality. The results showed that printing deviations decreased with increased mechanical strength and inner diameter. Subsequently, gelatin methacrylate (GelMA) NGCs was selected as a representative. It was found that printing conditions, including printing temperature, peeling, and shrinkage affected final NGC accuracy and quality. PC-12 cells cultured with the GelMA NGCs displayed non-toxic and promoted cell migration. Our research provides an effective, time-saving, and high-resolution technology for manufacturing multichannel NGCs with high fidelity, which may be used as reference templates for biomedical applications.
Anti-Asian Xenophobia, Hate Crime Victimization, and Fear of Victimization During the COVID-19 Pandemic
Authors: Lantz Brendan , Wenger Marin R.
Published: May 2022

While the World Health Organization advised against referring to COVID-19 using racial overtones, as the COVID-19 pandemic spread, many disparagingly called it the “Wuhan virus,” the “Chinese virus,” and other terms. In this context, the FBI warned police agencies about an expected increase in anti-Asian hate crimes during the early months of the pandemic. But, while some researchers and media outlets discussed these potential increases at length, very few studies have been able to directly assess the nature of anti-Asian hate and bias victimization during the pandemic. Following this, the current study directly examines variation in anti-Asian bias and victimization in the United States during the COVID-19 pandemic. Specifically, this research presents results from two studies using a survey of 3,163 non-Asian and 575 Asian American and Pacific Islander respondents, respectively. The first study examines the prevalence of anti-Asian xenophobia among the non-Asian sample and assesses differences in these prejudicial attitudes across respondent characteristics, while the second study examines variation in experiences with bias during the pandemic among the Asian sample. The results illustrate the ubiquity of anti-Asian sentiment, suggesting that those who indicate greater fear of the pandemic report more prejudicial attitudes, as well as important racial differences in these patterns. The results also demonstrate the extent to which the pandemic has impacted individual experiences with anti-Asian bias victimization, such that more than one-third of Asian respondents report bias victimization during the pandemic, and more than half of Asian respondents report that they know someone who has been victimized. These patterns have important implications for addressing COVID-19-related hate crime moving forward.
Muscle-Building Exercise and Weapon Carrying and Physical Fighting Among U.S. Adolescent Boys
Authors: Ganson Kyle T. , Testa Alexander , Rodgers Rachel F. , Jackson Dylan B. , Nagata Jason M.
Published: May 2022

This study aimed to determine the association between engagement in muscle-building exercise and weapon carrying and physical fighting among adolescent boys. Cross-sectional data from the 2019 Youth Risk Behavior Survey (U.S.) were analyzed ( N = 4120). Muscle-building exercise was assessed based on the number of days reported in the past 7 days, recategorized into four levels of engagement (no engagement [0 days], low engagement [1–2 days], moderate engagement [3–5 days], and high engagement [6–7 days]). Three forms of weapon carrying (general, on school grounds, gun carrying) and two forms of physical fighting (general, on school grounds) were assessed. Five logistic regression analyses with adjusted odds ratios (AOR) and 95% confidence intervals (CI) were used to determine the association between engagement in muscle-building exercise and weapon carrying and physical fighting, while adjusting for relevant demographic and control variables. Over 75% of participants reported engaging in muscle-building exercise. One in five (19.8%) participants reported any general weapon carrying in the past 30 days, 3.3% reported any weapon carrying at school in the past 30 days, 6.5% reported any gun carrying in the past 12 months, 28.0% reported any general physical fighting in the past 12 months, and 10.7% reported any physical fighting at school in the past 12 months. Logistic regressions showed that, compared to no engagement, participants who reported high engagement of muscle-building exercise had higher odds of general weapon carrying (AOR 2.18, 95% CI 1.54–3.07), gun carrying (AOR 2.12, 95% CI 1.23–3.64), and general physical fighting (AOR 2.07, 95% CI 1.53–2.79). These are novel findings that add to a growing literature related to engagement in muscularity-oriented behaviors among males. Prevention and intervention efforts are needed to ensure that adolescent boys engage in muscle-building exercise in ways that are not harmful and to reduce weapon carrying and physical fighting.
Shifts in Self-Reported Physical Activity, Sedentary Behavior, and Play Among Lower-Socioeconomic Children During the COVID-19 Pandemic: A Repeated Cross-Sectional Study
Authors: Wilson Kylie , Schmidt Annette , Hess Aaron , Vanos Jennifer , Ross Allison
Published: May 2022

Purpose

The lack of in-person schooling and participation in structured recreation activities during the COVID-19 pandemic may have altered children’s movement behaviors. This study assessed changes in children’s self-reported in school and out of school physical activity, sedentary behavior, and play before and during the pandemic.

Design

A repeated cross-sectional online survey was administered in February 2020 (pre-pandemic, in-person) and 2021 (during pandemic, remote).

Setting

Children attended an urban public school district in Phoenix (AZ) serving a low-income population.

Subjects

Students in grades 4–8 completed the survey in 2020 ( n = 253, 62% response rate) and 2021 ( n = 261, 77% response rate).

Measures

The survey included items from the Youth Activity Profile and three additional questions about play.

Analysis

Differences in mean scores and mean scores by gender were analyzed using one-way and two-way ANOVAs.

Results

Students reported less physical activity during remote recess in 2021 (M = 3.42, SD = .80 v. M = 2.99, SD = .86, p < .05). Physical activity outside of school decreased during the pandemic (M = 2.76, SD = 1.26 v. M = 2.53, SD = 1.18, p < .05). Most students (55%) reported playing less during the pandemic, but playing in new ways (67%).

Conclusion

Children may benefit from interventions to counter reduced movement experienced during the pandemic, particularly in under-resourced areas.
Prevalence and Correlates of Psychiatric Comorbidity and Multimorbidity in Parkinson’s Disease and Atypical Parkinsonian Syndromes
Authors: Patel Vinit , TS Jaisoorya , Kamble Nitish , Yadav Ravi , K Thennarassu , Pal Pramod Kumar , Reddy YC Janardhan
Published: May 2022

Purpose

Psychiatric comorbidity in Parkinson’s disease (PD) and atypical parkinsonian syndromes (APS) has been consistently associated with poor outcomes. However, the co-occurrence of multiple psychiatric disorders has been sparsely studied. This study examines the prevalence, patterns, and correlates of psychiatric comorbidity and multimorbidity among in-patients hospitalised with PD/APS.

Methods

Patients (N-110 [PD-71, APS-39]) underwent a single cross-sectional assessment. Psychiatric comorbidity was examined using the Mini International Neuropsychiatric Interview. Other domains assessed include sleep disorders, quality of life, and caregiver burden.

Statistical analysis

In addition to descriptive statistics, multinomial logistic regression was used to examine the effect of sociodemographic and clinical factors on comorbidities.

Results

The prevalence of psychiatric comorbidity in patients with PD and APS was 77.00% and 71.79%, with approximately half of those having co-occurrence of multiple psychiatric disorders. In both disorders, depression was the most common, followed by anxiety disorder. The two commonest patterns of multimorbidity reported in PD were the combination of depression and anxiety disorder, followed by the combination of psychosis, depression, and anxiety, with the order being reversed in APS. When compared to those without, those with single psychiatric comorbidity had higher odds of having REM sleep behaviour disorder and caregiver stress. Those with multiple psychiatric comorbidities had higher odds of being female, higher UPDRS part-1 scores, REM sleep behaviour disorder, poor sleep quality, and caregiver stress.

Conclusion

Psychiatric illness is highly comorbid among patients with PD/APS, with most having multiple co-occurring psychiatric illnesses. Clinicians must be aware to ensure early detection and intervention.
Investigation of the effect of graphene nanosheets on the properties of beech/polylactic acid flour composites
Authors: Ghorbanpour Ramtin , Ghasemi Ismaeil , Naeimian Navid
Published: May 2022

In this study, the effect of different amounts of graphene on the physical and mechanical properties of polylactic acid beech wood fiber composites were investigated. Beech flour and graphene were used as reinforcing phases with different weight percentages (0, 0.5, 1.5 and 2.5%). Samples were prepared by solution method and after pressing, mechanical properties such as flexural strength, flexural modulus, impact resistance and tensile strength and physical properties including differential scanning calorimetry test (DSC) and X-ray scattering test were measured. The results of analysis of variance showed that the effect of treatment was significant for flexural strength ( p < .05) and flexural modulus, impact resistance and tensile strength ( p < .01). The highest flexural strength, flexural modulus and tensile strength were related to treatment 8, which included 30% beech flour, 67.5% polylactic acid and 2.5% graphene, and the highest impact resistance was related to treatment 2, which included 20%. The weight of beech flour was 79.5% by weight of polylactic acid and 0.5% by weight of graphene, which were significantly different from other treatments ( p < .05). Based on the DSC, the melting temperature of the polymer matrix was transferred to higher temperatures by adding graphene nanosheets. The results of X-ray diffraction test showed that for all three treatments there is a similar trend in terms of peak graph and with increasing the concentration of graphene nanoparticles, only the peak intensity changed. It can be said that the addition of nanographene to beech-polylactic acid flour composites has improved the mechanical and physical properties.
The Influence of Gender Discrimination, Supervisor Support, and Government Support on Saudi Female Journalists’ Job Stress and Satisfaction
Authors: Muyidi Ahmed , Zhang Yan Bing , Gist-Mackey Angela
Published: May 2022

From the perspectives of Saudi female journalists, the current study examined the predictive associations between gender discrimination, supervisor support, government support, and work-related outcomes (i.e., job stress and job satisfaction). Supporting our predictions, regression analyses results revealed that perceptions of gender discrimination were positively and perceptions of supervisor support were negatively associated with job stress. In addition, we found that perceptions of supervisor support and government support had positive associations with job satisfaction. Findings are discussed considering women’s participation in the media industry in Saudi Arabia in relation to gender discrimination, supervisor and government support of women.
Impact of Pharmacist-Led Interventions to Improve Clinical Outcomes for Adults With Type 2 Diabetes at Risk of Developing Cardiovascular Disease: A Systematic Review and Meta-analysis
Authors: Alabkal Rahma M. , Medlinskiene Kristina , Silcock Jonathan , Graham Anne
Published: May 2022

Objective

The aim of this systematic review and meta-analysis of randomised controlled trials is to evaluate the impact of pharmacist-led interventions on cardiovascular disease (CVD) risk factors among patients with type 2 diabetes. Method: A literature review was conducted according to PRISMA guidelines using 4 electronic databases: Embase, MEDLINE, CINHAL and the Cochrane Central Register of Controlled Trials. We searched for pharmacist interventions among adults with type 2 diabetes and cardiovascular disease in randomised controlled trials from inception to May 2021 in primary care, diabetes clinics and hospitals. The clinical outcomes measured glycosylated haemoglobin (HbA1c), blood pressure (BP) and lipid profile. The non-clinical outcomes included medication adherence, smoking, health-related quality of life and the cost of the intervention. For the meta-analysis, clinical outcomes were pooled with the random effect model in RevMan 5.3. The Cochrane risk-of-bias tool was used to assess the quality of the included studies. Results: We retrieved 223 studies,141 of which were included in the review. Ten published articles met the inclusion criteria and were included in the meta-analysis. The pharmacists delivered the interventions alone or collaboratively with other healthcare professionals in hospitals or similar settings. The overall result showed a significant reduction in HbA1c (n = 10; standard deviation in mean value [SDM]: −.53%, 95% CI: −.84, −.23) and systolic BP (n = 10; [SDM]: −.35 mmHg, 95% CI: −.51, −.20) in pharmacist intervention groups. For the non-clinical outcomes, the review revealed variable results from pharmacist intervention compared with those standard care. Conclusion: Pharmacy interventions provide evidence for pharmacists’ decisive role in diabetes care management and reducing cardiovascular risk factors among adults with type 2 diabetes.
Efficacy and Safety of Sitagliptin in the Treatment of COVID-19
Authors: Mikhael Ehab Mudher , Ong Siew Chin , Sheikh Ghadzi Siti Maisharah
Published: May 2022

Background: Coronavirus disease 2019 (COVID-19) is associated with a high risk of mortality especially among diabetes mellitus (DM) patients. Effective treatments against COVID-19 can complement the vaccination effort worldwide. Many review articles studied the effects of the dipeptidyl peptidase 4 (DPP-4) inhibitors among COVID-19 patients and found conflicting results. This heterogeneity may be due to different systemic pleiotropic effects of different DPP-4 inhibitors. Sitagliptin appears to be one of the good DPP-4 inhibitors that have antiinflammatory and antithrombotic effect. Therefore, this review assessed the benefits and safety of sitagliptin in the treatment of COVID-19. Methods: A detailed literature review using the electronic databases of Pubmed and Google Scholar was conducted during July and August 2021 to find out studies that published in English language and discussed the role of sitagliptin for COVID-19 patients. Results: 14 articles were eligible and thus included in this narrative review. Nine of these articles agreed to the benefit of sitagliptin in the treatment of COVID-19, while 3 studies considered sitagliptin as non useful or even risky, and one study was neutral in its conclusion towards the usage of sitagliptin in COVID-19. Only one study focused on the safety of sitagliptin and found that it is safe. Conclusion: Sitagliptin has anti-inflammatory, antifibrotic and antiapoptotic properties; such effects may be beneficial in reducing risks of COVID-19. Sitagliptin has good safety and fair benefits to reduce mortality among DM patients with COVID-19. Further randomized clinical trials are needed to confirm these benefits especially among patients without DM.
Guest workers and development–security conflict: Managing labour migration at the Sino-Vietnamese border
Authors: Speelman Tabitha
Published: May 2022

This article investigates the increasing development–security conflict in China’s immigration management through the case of a policy trial regularizing Vietnamese labour migration in two Guangxi border cities. China’s border regions host low-income immigrant labourers from neighbouring nations. In the 2010s, China launched a series of policy initiatives to regulate temporary and irregular migrant flows. Based on fieldwork and policy research, this study analyses the development and early implementation of this trial, with a focus on state perspectives. It shows how state actors mobilize migrant temporariness and other policy tools within a negotiation process that aims to resolve tensions between developmental policy aims for transnational economic integration and a drive towards securitizing cross-border mobility. I conclude that state actors fail to reach a balance between the conflicting development and security concerns. I also argue that China’s current risk-averse policy environment makes the development–security policy conflict in its immigration management more difficult to resolve. My findings contribute to our understanding of contemporary Chinese policymaking, including immigration policymaking, as well as to the literature on the development–security nexus in temporary labour management schemes.
Challenges and opportunities for problem-based learning in higher education: Lessons from a cross-program Industry 4.0 case
Authors: Salvador Rodrigo , Barros Murillo Vetroni , Barreto Bernardo , Pontes Joseane , Yoshino Rui Tadashi , Piekarski Cassiano Moro , de Francisco Antonio Carlos
Published: May 2022

This article aims to identify the challenges and opportunities in cross-program problem-based learning (PBL) in higher education, based on an Industry 4.0 case with undergraduate and graduate students studying for engineering degrees. The method for this research comprised a cross-program course structured to bring together undergraduate and graduate students using a PBL approach. Five Industry 4.0-related projects were developed in collaboration with four multinational companies. The authors present the results of the projects and feedback from students, professors and industry partners. The results and feedback led to empirical findings on the challenges and opportunities of cross-program PBL in higher education. The findings contribute to the design and implementation of teaching and learning practices and educational policies at undergraduate and graduate levels. In the approach adopted, the undergraduate students acquired hands-on experience while the graduate students had the opportunity to supervise applied research and practice. The study highlights practices that can help to better prepare future industry professionals.
Impact of charge carrier transport properties on conductivity-temperature dependence of gellan gum-LiCF3SO3 biopolymer electrolyte
Authors: Abdul Aziz N.A , Tarmizi E.Z.M , Razak C.S.C , Noor I.M
Published: May 2022

Charge carrier density, mobility and diffusivity are three important transport properties in determining the ionic conductivity as well as the performance of solid polymer electrolyte. In this work, biopolymer electrolytes samples were prepared using the solution casting method by complexing gellan gum with different concentrations of lithium trifluoromethanesulfonate (3–15 wt.%). The values of charge carrier concentration, mobility, and diffusivity for electrolyte samples were estimated by fitting the Nyquist plot with an equation developed based on electrical impedance spectroscopy. At room temperature, the optimum electrolyte conductivity is 1.29×10−8 Scm−1 at 6 wt.% salt concentration. This result was supported by the highest percentage of free ions, 31.45%, observed in the FTIR method. As the temperature increases, the ionic conductivity increases to the optimum value before dropping. The highest conductivity of each sample was obtained at different temperatures (80°C–90°C) using the impedance method, whereas the percentage area of free ions was highest at 80°C for all samples with FTIR analysis. Overall, the ionic conductivity of this system has been dominated by the carrier charge density. Results suggest that, under these experimental conditions, electrical impedance spectroscopy is suitable for evaluating the charge transport properties at low temperatures.
An investigation on the material removal mechanism, surface porosity, and surface integrity in ultrasonic vibration assisted turning of porous stainless steel 316L
Authors: Ghorbani Bahman , Nategh Mohammad Javad , Karafi Mohammad Reza
Published: May 2022

The machining of porous materials is commonly accompanied with high and irregular cutting forces, high cutting temperature, poor surface integrity, and severe tool wear. The porous materials are considered difficult to be machined. Porosity reduces the rate of heat transfer; moreover, it impairs the continuous cutting and therefore leads to cyclic loads. The main objective of the present study is to investigate the influence of superimposing ultrasonic vibration to the cutting motion of the cutting tool on the surface integrity of the porous materials. For this purpose, the mechanism of chip removal in vibration assisted machining of porous materials was analyzed and porous stainless steel 316L specimens were machined by ultrasonic vibration assisted turning. It was illustrated by the porosimetry of the machined surfaces that the surfaces machined by conventional turning had higher rate of surface porosity compared with ultrasonic vibration assisted turning. In the latter process, the SEM images of the machined surfaces manifested the existence of a kind of rubbing mechanism and material overlaps, which was attributable to the friction existing between the cutting tool with micro scale reciprocating motion and the surface of the workpiece. The overall impact of imposing ultrasonic vibration to the cutting tool motion in the cutting direction was the achievement of a trade-off between preserving the porosity and improvement of the surface quality. This effect was bolstered by increasing the vibration amplitude.
Study on the forming limit of rectangular-ribbed profile (日-shaped section) in rotary bending with flexible core die
Authors: Liang Ce , Huang Fulei , Li Yi , Liang Jicai
Published: May 2022

The profile with rectangular ribbed (日-shaped) section is applied to the anti-collision beam of commercial vehicles, which not only improves the anti-collision performance but also improves the lightweight of the car. With the gradual decrease of the bending radius of the profile, the profile is prone to defects such as wrinkling of the inner wall or fracture of the outer wall. In this paper, the ABAQUS, a finite element simulation software, is used to establish the simulation model of the profile with rectangular ribbed section during the process of rotary draw bending, and the stress and strain laws are analyzed. The bending forming limit of the profile with rectangular ribbed section is studied by choosing the fracture of the outer wall as the evaluation standard. And the influences of bending speed, friction coefficient, and thickness on the forming limit are obtained. The minimum bending radius decreases as the bending speed increases and increases with increasing of friction coefficient and thickness.
Kinematics and dynamics simulations of cold orbital forging machines based on ADAMS
Authors: Chen Mingzhang , Zhang Xuancheng , Zhuang Wuhao , Shu Yuwen , Zhou Zijian , Xiong Wei
Published: May 2022

The vibration of cold orbital forging (COF) machines is detrimental to the quality of the forged part. Therefore, it is necessary to carry out kinematics and dynamics analyses, study the vibration of the COF machine, and provide effective methods for reducing the vibration. In terms of kinematics and dynamics analyses, the mathematical modeling and model solving processes are complicated, and it takes a long time to obtain the kinetic and vibration performances of the COF machine. In this study, the kinematics and dynamics models of the COF machine were investigated. Subsequently, automatic dynamic analysis of mechanical systems (ADAMS) was applied to conduct kinematics and dynamics simulations. The simulation process was convenient and time-saving, and the simulation of the COF machine was effectively verified by conducting an experiment. Based on the simulation results, the kinetic and vibration performances of the COF machine were studied. In addition, a structure optimization method for the COF machine is proposed. Based on the singularity stability theory, the Hopf bifurcation and chaos phenomena are less likely to occur on the optimized COF machine, and therefore the vibration of the optimized COF machine is stable. Meanwhile, the structure optimization method was proven to be effective in reducing the vibration of the COF machine, which improves the quality of the forged part.
Single point incremental bending: Bending load evaluations and process validation
Authors: Singh Arshpreet , Agrawal Anupam
Published: May 2022

Sheet metal or monolithic thin structured components with complex freeform geometries are used in wide range of applications in aerospace, marine and automobile sectors. Fabrication of such complicated geometries and profiles generally requires complex manufacturing setup (dies, jigs and punches) resulting in process inflexibility, in addition to huge tooling and equipment costs. In the present work, a novel process ‘single point incremental bending’ (SPIB) is proposed. In principle, it is similar to single point incremental forming process. SPIB is a die less bending operation where a solid hemispherical shaped single point tool is used to locally bend the sheet metal to a desired shape incrementally using a computer numeric controlled setup or certain robotic platforms. In addition to that, an experimental and finite element analysis based numerical study on the bending load patterns and trends in single point incremental sheet metal bending has been presented. Detailed investigation of various commercial sheet metals and various parametric effects on bending load is also performed. The influence of sheet material, material anisotropy and four major process parameters – sheet thickness, tool diameter, incremental bending angle and sheet height to length ratio on the bending loads is investigated.
Mechanism for tension adjustment in tendon driven remote center-of-motion mechanism for minimally invasive surgery
Authors: Singh Amanpreet , Khatait Jitendra P
Published: May 2022

Tendon drive is used for transmission design in applications ranging from wearable rehabilitation and surgical robots to industrial robots. For their efficient operation, one of the principal design requirements is to have adequate tension in the tendon element. This paper introduces a novel mechanism for tension adjustment using a secondary cable-pulley arrangement via a lever mechanism. An adjustment in a tension spring applies a force in the tendon element meant for the transmission of remote centre-of-motion (RCM) mechanism for medical robotic application. Thereafter, the current work presents the kinematic and force analyses of the proposed concept along with a series of plots of various mechanism parameters. The variation of these parameters is in good agreement with the physical motion of the devised mechanism. As compared to the conventional methods of tension adjustment, the proposed concept is a better solution for problems that arise due to low manufacturing tolerances and the need for independent tension adjustment in a multi degrees-of-freedom tendon driven RCM mechanism. In the preferred embodiment, it is proposed to use cables (wire-ropes) as tendon elements to drive a mechanically constrained double-parallelogram-based RCM mechanism which is extensively used for Minimally Invasive Surgery. From this implementation, it is learnt that the presented mechanism can be implemented in several configurations. However, this paper presents the preferred embodiment only which meets the demand, of invariant tendon length, of the RCM mechanism under consideration. An initial prototype is made from acrylic sheets, PLA material, and standard elements (like bearings, pulleys, aluminum pins, 0.5 mm stainless-steel wire-rope, etc.) using laser micromachining and 3D printing.
Punch-less and die-less sheet hydroforming process for manufacturing of serpentine-shaped micro-channels in ultra-thin sheets
Authors: Sudarsan Coomar , Panda Sushanta Kumar
Published: May 2022

In the present work, novel serpentine-shaped micro-channels were successfully fabricated in ultra-thin sheets of AA1050, C101, and SS304 materials using the sheet hydroforming (SHF) process. In-house fabrication methods, namely punch-less SHF and die-less SHF processes were designed and developed on a 20-t press to manufacture these channels. The finite element (FE) modeling of both processes was developed for the prediction of the deformation behavior of these sheets. The elasto-plastic FE models incorporated the elastic properties, Barlat 89 anisotropic yield model, and Hollomon hardening law for all the three sheets, and their corresponding forming limit diagrams (FLDs) were implemented as damage criteria. It was observed that the maximum pressure was 28 MPa and 32 MPa for the punch-less and die-less SHF process, respectively. The manufacturability of the hydroformed channels was examined through channel depth, aspect ratio, and thickness distribution. The average channel depth and aspect ratio were found to be higher in the case of the die-less SHF compared to punch-less SHF. The failure occurred in the AA1050 channel under plane strain deformation mode near the die corner region and punch corner region for punch-less and die-less SHF processes, respectively, indicated by a sudden dip in the thickness distribution profile. Moreover, the surface quality of the formed channels was investigated through surface roughness value, and this was further correlated with effective plastic strain incurred in the deformation process. It was observed that the surface roughness of the deformed channels fabricated by the punch-less SHF process was lower than those formed through the die-less SHF process in the present study.
Automatic image positioning of a rail train number using speed-up robust features and stroke width transform
Authors: Xing Zongyi , Zhang Zhenyu , Yao Xiaowen
Published: May 2022

The rail train number is the only sign information of the vehicle. It is very important to use the image processing method to locate the train number to improve the efficiency of rail train management. Therefore, an automatic image positioning framework for rail train numbers is developed. First, aiming at the problem of low contrast between the rail train number and vehicle body caused by insufficient illumination of the rail train in a tunnel and indoor, the improved single-scale Retinex algorithm based on brightness control is used to enhance the image, which provides the basis for subsequent train number image positioning. Then, a train number location algorithm based on speed-up robust features and stroke width transform is proposed to locate the train number accurately. The experimental results show that the accuracy of the developed method is 96.91% in the complex environment of uneven illumination and large distortion of rail train numbers.
Optimization of heat affected zone in laser cutting of Kevlar-29 fiber composite using hybrid response surface based grey wolf optimization (RSGWO) algorithm
Authors: Prajapati Akanksha , Norkey Gavendra , Gautam Girish D
Published: May 2022

The large strength-to-weight rate and superior mechanical qualities, Kevlar fiber reinforced polymers (KFRP) are commonly utilized in the aerospace, vehicle, and energy sectors. The fine machining of KFRPs in these sectors was required for specific applications. Because of low matrix cracking, burr development, negligible tool wear, and fiber delamination, laser beam cutting (LBC) is a promising alternative to traditional cutting processes in KFRP cutting. During pulsed laser cutting of neodymium-doped yttrium aluminum garnet of the K-29 (Kevlar composite laminate) for the 1.25 mm thickness, the heat affected zone (HAZ) was determined experimentally at various settings of the lamp current, pulse frequency, and cutting speed. A second-order regression model for HAZ was demonstrated by using experimentally obtained data. A novel response surface-based grey wolf optimization (RSGWO) algorithm has also been proposed and used to discover optimal levels of process parameter conditions for minimizing HAZ. The RSGWO technique has proposed ideal values for the specified parameters at low pulse frequency (20 Hz) and lamp current (160 A), as well as greater air pressure (10 kg/cm2) with cutting speed (200 mm/min). At optimal cutting parameter values, a 14.92% improvement in HAZ was observed. Furthermore, parametric effects have been studied, and it has been discovered that compressed air pressure is the valuable parameter for HAZ for laser-cut KFRP composite, while lamp current (I) is the least important.
Numerical analysis and experimental research on the accuracy decay of a ball screw with geometric errors under non-constant operating conditions
Authors: Qi Baobao , Cheng Qiang , Liu Zhifeng , Chen Chuanhai , Guo Jinyan , Zhao Jiajia
Published: May 2022

The ball screw (BS) has become an indispensable key functional component in many fields, such as precision manufacturing equipment and intelligent manufacturing production lines. Inevitable geometric errors and non-constant operating conditions affect the accuracy decay of the BS component. In this paper, a numerical analysis method of this accuracy decay with geometric parameters errors, under non-constant operating conditions, is established. The accuracy degradation of the BS, under a single non-constant operation condition or multiple non-constant operating conditions, is analyzed, using a proposed numerical analysis method. The average value of the relative error between numerical analysis and theoretical model results was 5.52%, 5.66%, and 5.40%, under the three operating conditions of non-constant rotation rate (RR), non-constant contact load (CL), and non-constant rotation rate and contact load (RR + CL), respectively. And the maximum relative error value was 11.11%, 11.11%, and 10.98%. In addition, the numerical analysis method of BS accuracy degradation was compared to experimental tests. The average value of the relative error between numerical analysis outcome and experimental tests was 7.07%, 6.08%, 6.56%, and the maximum relative error value was 11.11%, 14.29%, and 13.04% under the three operating conditions of RR, CL, and RR + CL, respectively.
Failure analysis and optimization method research on sealing of deep shale gas ultra-high-pressure fracturing packer rubber
Authors: Dong Liangliang , Liu Jinlei
Published: May 2022

The contact pressure distribution computation model was established to evaluate the internal and external sealing performance of packer rubber. And the results show that the internal sealing performance of packer rubber may be lower than the external side. The weights of the key parameters which influence the internal and external sealing performance of the rubber tube are obtained by calculation. The optimized structural parameters are obtained by genetic algorithm, and the sealing performance is increased by 21%. The research work is significant to improve the packer’s sealing performance and adapt deep shale gas wells ultra-high pressure fracturing conditions.
The full-parametric development of the intake ports by using genetic algorithm in a four-valve diesel engine
Authors: Gao Yuchuan , Lu Zhen , Wang Tianyou , Shi Lei , Feng Yizhuo , Lu Tianlong
Published: May 2022

In-cylinder flow characteristics, which are mainly determined by the intake ports, have a decisive influence on the mixture formation and combustion process of internal combustion (IC) engines. To develop the optimum intake ports in a four-valve diesel engine, the full-parametric design method coupled with genetic algorithm (GA) and artificial neural network (ANN) was adopted in this study. Different from previous studies, the full-parametric templates for the tangential and helical ports were established. Then, to improve the precision of the CFD result which was used to train the ANN, the near-wall region affected by viscosity was resolved by the “enhanced wall treatment” during the simulation process. Besides, considering the interaction between the outlets of adjacent intake ports in the four-valve engine, the ANN was divided into three parts to better predict the flow performance of the combined intake ports. Finally, the developed intake ports based on ANN and GA were machined to the flow box and validated by the steady flow test. The low deviation of 4.71% in swirl ratio between the design target and the experiment result confirms that this method can be well applied to the development of the intake ports in a four-valve diesel engine.
Directional dependence of the mechanical properties of structural adhesive joints with curing-induced pre-deformations
Authors: Beule Felix , Teutenberg Dominik , Meschut Gerson
Published: May 2022

Owing to the implementation of multi-material construction methods in modern lightweight construction and the associated use of adhesive bonding technology, thermally induced relative displacements of the joining partners occur during the curing process. The resulting extremely complex thermo-chemo-mechanical stresses can influence the properties of the adhesive layers and reduce the load-bearing capacity. In this study, experiments are conducted to examine the influence of process-related thermal relative displacements on the mechanical properties of adhesives. The results show an anisotropy of the mechanical properties of the pre-deformed adhesive layers, depending on the magnitude and direction of the relative displacement.
Thermal analysis of a box type solar cooker coupled with Fresnel lens
Authors: Engoor Gulsavin Guruprasad , Shanmugam S , Veerappan AR
Published: May 2022

The thermal analysis of a Box-type solar cooker (BTSC) coupled with two Fresnel lens magnifiers (FLMG) is presented in this paper. A time dependent numerical model based on heat balances occurring at different parts of the cooker was prepared and executed in a MATLAB program. To check the robustness of the model, the temperature variation of the cooker elements obtained by the mathematic modeling was compared with the experimental results. The comparison showed the average estimated error between the experimental and numerical values fell between 0.73–3.49 percentage. In order to check the effectiveness of the FLMG, First Figure of merit (F1) and Second figure of merit (F2) tests were performed as per international testing procedures. The first figure of merit value increased from 0.11 to 0.12 m2 °C/W, converting the BTSC from B grade category to A grade. The Second figure of merit rose from 0.43 to 0.45 by utilizing the FLMG, indicating the improvement in heat exchange to the load in the cooking vessel. The temperature of all the components of the BTSC was increased by incorporating the FLMG. The paper also discusses the variation of different heat transfer coefficients coming to play in the cooker. Basmati rice was successfully cooked by the solar cooker in an interval of 58 min.
Numerical study on the effect of oscillation on the deformation behavior of single point incremental formed part
Authors: Nikhare Chetan P.
Published: May 2022

The paper reports the deformation behavior of single point incremental formed part with sheet oscillation. Single point incremental forming is an emerging manufacturing technology. This technology provides the competition to the other innovative technologies such as electric-assisted manufacturing, hydroforming, high-speed forming, etc., to produce the lightweight and highly deformed components. Single point incremental forming is the die-less sheet metal forming process in which the single point tool incrementally forces any single point of sheet metal at any processing time to undergo plastic deformation. In single point incremental forming, the part stays fixed and the tool pin makes the planar and downward motion to shape the part. It has several advantages over the conventional process such as high process flexibility, elimination of die, complex shape, and better formability. Previous literature provides enormous research on the formability of metal during this process, process with various metals and hybrid metals, the influence of various process parameters, but research on the deformation behavior of the part through the oscillation of the tool was limited. In this paper, the single point incremental forming was simulated on ABAQUS finite-element software. The spiral tool path was studied. First, the part was formed without oscillation. Then the oscillation of the sheet with the help of a die and blank holder was set with a frequency to deform the part. The variation of frequency and amplitude was also studied. The formability of the part was analyzed and compared. The deformation, profile shape, strain path, thickness, and force requirement were analyzed and presented. It was found that with lower cycles the maximum stress increases with an increase in amplitude. Also, with an increase in the number of cycles the achieved strain values were lower as compared to the no oscillation case for the same cup height and thus higher deformation is possible with oscillation.
Robust adaptive sliding mode control strategy of uncertain nonlinear systems
Authors: Soukkou Yassine , Tadjine Mohamed , Zhu Quan Min , Nibouche Mokhtar
Published: May 2022

This paper presents a robust adaptive sliding mode controller scheme as applied to a class of uncertain nonlinear systems with parametric uncertainties and external disturbances. First, a sliding mode control technique is designed. Then, the proposed robust adaptive control schemes are applied to estimate the parametric uncertainties and the upper bound value of the external disturbances by using adaptive laws, ensure robustness in presence of parametric uncertainties and external disturbances, and reduce chattering problem by introducing an hyperbolic tangent function. Lyapunov stability theory is used to analyze the stability of the closed-loop system. As an exemplar, the schemes have been applied to a quadrotor unmanned aerial vehicle (QUAV) model. Simulation results for the control of the QUAV model are provided to illustrate the performance of the proposed robust adaptive sliding mode control scheme and demonstrate that the proposed method has good tracking performance. The simulation results clearly prove the effectiveness of our approach.