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Friction 2024年第4期12卷 796-811页

作者： Samuel BOND Robert l.jackson German MIllS Department of Chemistry and Biochemistry Auburn UniversityAuburn 36849-5412USA Department of Mechanical Engineering Auburn UniversityAuburn 36849-5412USA

leakage currents accelerate surface degradation of metal contacts via small scale arcing across lubricating films,but recent observations suggest that metallic nanoparticle additives in lubricants may be useful to improve contact performance.These findings prompted a study that examined electrically induced surface pitting of steel contacts in the presence of several lubricating greases including some containing nanometer-sized colloidal silver(Ag)particles.Reciprocating rolling sphere-on-disk experiments were conducted under electro-tribological loads employing polyurea greases derived from mineral and synthetic base oils with and without additives.Friction forces and electrical resistance were monitored continuously during the tests;surface changes were characterized by means of optical spectroscopy,stylus profilometry,and scanning electron microscopy(SEM)including compositional analysis using energy dispersive spectroscopy(EDS).The observations demonstrate that surface pitting induced by arcing occurs mainly at the points were the rolling motion changes direction and that eroded metal is deposited along the wear grove.Micron-sized pits are formed which contain carbon and oxygen indicating that arcing causes decomposition of the hydrocarbon lubricants.Numerous findings indicate a significant inhibition of pitting is induced by the Ag nanoparticles;some greases containing other additives exhibit a similar,although less pronounced,effect.

关键词： electric motor bearings wheel bearings electric vehicles arcing electrically induced bearing damage pitting leakage current stray current

Himalayas as a global hot spot of springtime stratospheric intrusions:Insight from isotopic signatures in sulfate aerosols

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Research in Cold and Arid Regions 2024年第1期16卷 5-13页

作者： Kun Wang ShiChang Kang Mang lin PengFei Chen Chaoliu li XiuFeng Yin Shohei Hattori Teresa l.jackson JunHua Yang YiXi liu Naohiro Yoshida Mark HThiemens State Key laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of Sciences(CAS)LanzhouGansu 730000China State Key laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryCASGuangzhouGuangdong 510640China University of Chinese Academy of Sciences Beijing 100049China International Center for Isotope Effects Research(ICIER) School of Earth Sciences and EngineeringNanjing UniversityNanjingJiangsu 210023China Frontiers Science Center for Critical Earth Material Cycling State Key Laboratory for Mineral Deposits ResearchSchool of Earth Sciences and EngineeringNanjing UniversityNanjingJiangsu 210023China Department of Chemical Science and Engineering School of Materials and Chemical TechnologyTokyo Institute of Technology4259 Nagatsuta-choMidori-kuYokohamaKanagawa 226-8502Japan Department of Chemistry and Biochemistry University of California San DiegoLa JollaCA 92093-0021USA Earth-life Science Institute Tokyo Institute of TechnologyMeguro-kuTokyo 152-8551Japan National Institute of Information and Communications Technology KoganeiTokyo 184-8795Japan

Downward transport of stratospheric air into the troposphere(identified as stratospheric intrusions)could potentially modify the radiation budget and chemical of the Earth's surface atmosphere.As the highest and largest plateau on earth,the Tibetan Plateau including the Himalayas couples to global climate,and has attracted widespread attention due to rapid warming and cryospheric shrinking.Previous studies recognized strong stratospheric intrusions in the Himalayas but are poorly understood due to limited direct evidences and the complexity of the meteorological dynamics of the third pole.Cosmogenic^(35)S is a radioactive isotope predominately produced in the lower stratosphere and has been demonstrated as a sensitive chemical tracer to detect stratospherically sourced air mass in the planetary boundary layer.Here,we report 6-month(April–September 2018)observation of^(35)S in atmospheric sulfate aerosols(^(35)SO_(4)^(2-))collected from a remote site in the Himalayas to reveal the stratospheric intrusion phenomenon as well as its potential impacts in this region.Throughout the sampling campaign,the^(35)SO_(4)^(2-)concentrations show an average of 1,070±980 atoms/m^(3).In springtime,the average is 1,620±730 atoms/m^(3),significantly higher than the global existing data measured so far.The significant enrichments of^(35)SO_(4)^(2-)measured in this study verified the hypothesis that the Himalayas is a global hot spot of stratospheric intrusions,especially during the springtime as a consequence of its unique geology and atmospheric couplings.In combined with the ancillary evidences,e.g.,oxygen-17 anomaly in sulfate and modeling results,we found that the stratospheric intrusions have a profound impact on the surface ozone concentrations over the study region,and potentially have the ability to constrain how the mechanisms of sulfate oxidation are affected by a change in plateau atmospheric properties and conditions.This study provides new observational constraints on stratospheric intrusions in the Himalayas,which woul

关键词： Himalayas Stratospheric intrusions Cosmogenic^(35)SO_(4)^(2-) Ozone Atmospheric oxidation

Modelling dynamic pantograph loads with combined numerical analysis

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Railway Engineering Science 2024年第1期32卷 81-94页

作者： F.F.jackson R.Mishra J.M.Rebelo J.Santos P.Antunes J.Pombo H.Magalhaes l.Wills M.Askill School of Computing and Engineering University of HuddersfieldHuddersfieldUK School of Computing and Engineering Institute of Railway ResearchUniversity of HuddersfieldHuddersfieldUK IDMEC Instituto Superior TecnicoUniversidade de LisboaLisbonPortugal ISEl Instituto Politecnico de LisboaLisbonPortugal Hitachi Rail Newton AycliffeUK Wabtec/Brecknell Willis ChardUK

Appropriate interaction between pantograph and catenary is imperative for smooth operation of electric trains.Changing heights of overhead lines to accommodate level crossings,overbridges,and tunnels pose significant challenges in maintaining consistent current collection performance as the pantograph aerodynamic profile,and thus aerodynamic load changes significantly with operational height.This research aims to analyse the global flow characteristics and aerodynamic forces acting on individual components of an HSX pantograph operating in different configurations and orientations,such that the results can be combined with multibody simulations to obtain accurate dynamic insight into contact forces.Specifically,computational fluid dynamics simulations are used to investigate the pantograph component loads in a representative setting,such as that of the recessed cavity on a Class 800 train.From an aerodynamic perspective,this study indicates that the total drag force acting on non-fixed components of the pantograph is larger for the knuckle-leading orientation rather than the knuckle-trailing,although the difference between the two is found to reduce with increasing pantograph extension.Combining the aerodynamic loads acting on individual components with multibody tools allows for realistic dynamic insight into the pantograph behaviour.The results obtained show how considering aerodynamic forces enhance the realism of the models,leading to behaviour of the pantograph-catenary contact forces closely matching that seen in experimental tests.

关键词： Pantograph-catenary interaction Pantograph aerodynamics Computational fluid dynamics Pantograph loads Current collection performance

Human resource management Robert l. Mathis, John H. jackson. 8th ed.

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levels of Polycyclic Aromatic Hydrocarbons (PAHs) in Healthcare Waste Incinerators’ Bottom Ash from Five County Hospitals in Kenya

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作者： Robert l. Mathis John H. jackson.

来源：畅想之星图书光盘版（南... 评论

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Journal of Environmental Protection 2024年第3期15卷 318-337页

作者： Muriithi jackson Githinji Paul Mwangi Njogu Zipporah Nganga Mohamed Karama Institute of Tropical Medicine and Infectious Diseases (ITROMID) Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Institute of Energy and Environmental Technology Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Academic Research and Student Affairs South Eastern Kenya University Kitui Kenya Public Health and Epidemiology Umma University Kajiado Kenya

Health-care waste contains potentially harmful microorganisms and compounds which can infect and affect hospital patients, healthcare workers, the general public and environment. Therefore, management of health care waste requires safe handling, treatment and disposal procedures. While incineration reduces the volume and quantity of waste for final disposal, it leads to the production of fly and bottom ashes laden with toxic incomplete combustion products such as Polycyclic Aromatic Hydrocarbons (PAHs), dioxins, furans and heavy metals. This exposes workers who handle and dispose the bottom ashes, hospital patients, the general public and environment. The goal of this study was to determine the total and individual levels of 16 most prevalent and toxic PAHs. Bottom ash samples were collected from incinerators in five county hospitals in Kenya, namely;Moi-Voi, Narok, Kitale, Makindu and Isiolo. Bottom ash samples were collected over a period of six months from the five hospitals. The samples were then sieved, homogenised and stored at 4°C in amber coloured glass containers. The PAHs were extracted using 30 ml of a hexane-acetone solvent (1:1) mixture by ultrasonication at room temperature (23°C) for 45 minutes. The PAHs were then analyzed with a GC-MS spectrophotometer model (Shimadzu GCMS-QP2010 SE) connected to a computer work station was used for the PAHs analysis. The GC-MS was equipped with an SGE BPX5 GC capillary column (30 m × 0.25 mm × 0.25 μm) for the separation of compounds. Helium was used as the carrier gas at a flow rate of 15.5 ml/minute and 14.5 psi. 1 μl of the sample was injected at 280°C, split mode (10:1). The oven programming was set for a total runtime of 40 minutes, which included: 100°C (2-minute hold);10°C /min rise to 200°C;7°C /min rise to 249°C;3°C /min rise to 300°C (2-minute hold). The interface temperature was set at 290°C. Analysis was done in Selected Ion Monitoring (SIM) mode and the peak areas of each of the PAHs were collected from the chromatograph and used for quantification o

关键词： PAHs GC-MS Healthcare Wastes Disposal Incinerator Bottom Ash

Metagenomic markings of myeloid malignancies

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Genes & Diseases 2023年第1期10卷 4-6页

作者： An Dinh Duy Nguyen Maryssa Shanteau-jackson Thomas laFramboise Department of Genetics and Genome Sciences School of MedicineCase Western Reserve UniversityClevelandOH44106USA

Human microbiome studies have exploded in number in recent years with the advent of high-throughput sequencing methods.The dramatic increase in sensitivity facilitated by deep-sequencing capability has led to hundreds of studies characterizing microbial communities in multiple human tissues,as well as the relationships between the composition of these communities and disease.

关键词： methods. myeloid hundreds

Boundary element method (BEM) applied to the rough surface contact vs. BEM in computational mechanics

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Friction 2019年第4期7卷 359-371页

作者： Yang XU Robert l.jackson Mechanical Engineering Department Auburn University

In the numerical study of rough surfaces in contact problem, the flexible body beneath the roughness is commonly assumed as a half-space or a half-plane. The surface displacement on the boundary, the displacement components and state of stress inside the half-space can be determined through the convolution of the traction and the corresponding influence function in a closed-form. The influence function is often represented by the Boussinesq-Cerruti solution and the Flamant solution for three-dimensional elasticity and plane strain/stress, respectively. In this study, we rigorously show that any numerical model using the above mentioned half-space solution is a special form of the boundary element method(BEM). The boundary integral equations(BIEs) in the BEM is simplified to the Flamant solution when the domain is strictly a half-plane for the plane strain/stress condition. Similarly, the BIE is degraded to the Boussinesq-Cerruti solution if the domain is strictly a half-space. Therefore, the numerical models utilizing these closed-form influence functions are the special BEM where the domain is a half-space(or a half-plane). This analytical work sheds some light on how to accurately simulate the non-half-space contact problem using the BEM.

关键词： boundary element method rough surface contact half-space half-plane Flamant solution Boussinesq-Cerruti solution

Performance Evaluation ofMulti-Agent Reinforcement learning Algorithms

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Intelligent Automation & Soft Computing 2024年第2期39卷 337-352页

作者： Abdulghani M.Abdulghani Mokhles M.Abdulghani Wilbur l.Walters Khalid H.Abed Department of Electrical&Computer Engineering and Computer Science Jackson State UniversityJacksonMS 39217USA

Multi-Agent Reinforcement learning(MARl)has proven to be successful in cooperative assignments.MARl is used to investigate how autonomous agents with the same interests can connect and act in one team.MARl cooperation scenarios are explored in recreational cooperative augmented reality environments,as well as realworld scenarios in robotics.In this paper,we explore the realm of MARl and its potential applications in cooperative assignments.Our focus is on developing a multi-agent system that can collaborate to attack or defend against enemies and achieve victory withminimal damage.To accomplish this,we utilize the StarCraftMulti-Agent Challenge(SMAC)environment and train four MARl algorithms:Q-learning with Mixtures of Experts(QMIX),Value-DecompositionNetwork(VDN),Multi-agent Proximal PolicyOptimizer(MAPPO),andMulti-Agent Actor Attention Critic(MAA2C).These algorithms allow multiple agents to cooperate in a specific scenario to achieve the targeted mission.Our results show that the QMIX algorithm outperforms the other three algorithms in the attacking scenario,while the VDN algorithm achieves the best results in the defending scenario.Specifically,the VDNalgorithmreaches the highest value of battle wonmean and the lowest value of dead alliesmean.Our research demonstrates the potential forMARl algorithms to be used in real-world applications,such as controllingmultiple robots to provide helpful services or coordinating teams of agents to accomplish tasks that would be impossible for a human to do.The SMAC environment provides a unique opportunity to test and evaluate MARl algorithms in a challenging and dynamic environment,and our results show that these algorithms can be used to achieve victory with minimal damage.

关键词： Reinforcement learning Rl multi-agent MARl SMAC VDN QMIX MAPPO

A bioactive material with dual integrin-targeting ligands regulates specific endogenous cell adhesion and promotes vascularized bone regeneration in adult and fetal bone defects

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Bioactive Materials 2023年第2期20卷 179-193页

作者： Dake Hao Ruiwu liu Tomas Gonzalez Fernandez Christopher Pivetti Jordan Elizabeth jackson Edwin Samuel Kulubya Hong-Jiang Jiang Hai-Yang Ju Wen-liang liu Alyssa Panitch Kit S.lam JKent leach Diana l.Farmer Aijun Wang Department of Surgery School of MedicineUniversity of California DavisSacramentoCA95817United States Institute for Pediatric Regenerative Medicine Shriners Hospitals for ChildrenSacramentoCA95817United States Department of Biochemistry and Molecular Medicine School of MedicineUniversity of California DavisSacramentoCA95817United States Department of Biomedical Engineering University of California DavisDavisCA95616United States Wendeng Orthopaedic Hospital No.1 Fengshan RoadWendeng264400ShandongChina Department of Orthopaedic Surgery School of MedicineUniversity of California DavisSacramentoCA95817United States

Significant progress has been made in designing bone materials capable of directing endogenous cells to promote vascularized bone regeneration.However,current strategies lack regulation of the specific endogenous cell populations for vascularized bone regeneration,thus leading to adverse tissue formation and decreased regenerative efficiency.Here,we engineered a biomaterial to regulate endogenous cell adhesion and promote vascularized bone regeneration.The biomaterial works by presenting two synthetic ligands,llP2A and lXW7,explicitly targeting integrinsα4β1 andαvβ3,respectively,expressed on the surfaces of the cells related to bone formation and vascularization,such as mesenchymal stem cells(MSCs),osteoblasts,endothelial progenitor cells(EPCs),and endothelial cells(ECs).In vitro,the llP2A/lXW7 modified biomaterial improved the adhesion of MSCs,osteoblasts,EPCs,and ECs via integrinα4β1 andαvβ3,respectively.In an adult rat calvarial bone defect model,the llP2A/lXW7 modified biomaterial enhanced bone formation and vascularization by synergistically regulating endogenous cells with osteogenic and angiogenic potentials,such as DlX5^(+)cells,osteocalcin^(+)cells,CD34^(+)/CD45-cells and CD31^(+)cells.In a fetal sheep spinal bone defect model,the llP2A/lXW7 modified biomaterial augmented bone formation and vascularization without any adverse effects.This innovative biomaterial offers an off-the-shelf,easy-to-use,and biologically safe product suitable for vascularized bone regeneration in both fetal and adult disease environments.

关键词： Integrin-based ligands Endogenous stem cells Bone formation Vascularization Adult and fetal bone defects

WONCA研究论文摘要汇编——初级医疗提供遗传学教育干预措施的系统评价

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中国全科医学 2016年第23期19卷 2857-2857页

作者： PANEQUE M TURCHETTI D jackson l 本刊编辑部

背景在初级医疗中可以看到这样的现象,即至少10%的患者存在遗传的影响。然而,具有高遗传风险疾病的患者可能没有被识别,因此治疗建议可能没有提及或者管理不恰当。初级医务工作者缺乏遗传学知识,在日常工作中缺少遗传学相关检测,开展遗... 详细信息

背景在初级医疗中可以看到这样的现象,即至少10%的患者存在遗传的影响。然而,具有高遗传风险疾病的患者可能没有被识别,因此治疗建议可能没有提及或者管理不恰当。初级医务工作者缺乏遗传学知识,在日常工作中缺少遗传学相关检测,开展遗传学服务不足。本研究的目的是评估初级医疗中采取的遗传学教育的干预措施。方法本研究采用标准审查和传播中心指定的系统评价步骤,在5个数据库中检索相关文献。纳入涵盖初级医务工作者采用遗传教育学干预结局的文献,对每篇文献的结果进行分组和主题归类。结果共纳入11篇文献。确定的5个主题分别为:既往经历、信心变化、知识变化、实践变化以及满意度和反馈。其中5篇文献介绍通过执行教育计划,医务工作者的知识层面得到提高,但是仅限定在特定的领域;6篇文献介绍医务工作者的信心得到改善;然而实践行为并没有明显的改变。结论目前,缺乏相关而有质量的文献证实遗传学教育干预措施在初级医务工作者中的作用。教育措施应该在实践、信心和知识方面进行评估,以判断教育措施是否在改善患者遗传风险评估和适合的管理措施方面发挥显著作用。

关键词：干预措施遗传学教育学 WONCA 医疗论文摘要系统医务工作者