检索结果-南通市图书馆

Laser Polishing of Laser Powder Bed Fusion AlSi10Mg Parts—Influence of Initial Surface Roughness on Achievable Surface Quality

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Materials Sciences and Applications 2021年第1期12卷 15-41页

作者： Markus Hofele Andre Roth Jochen Schanz David K. Harrison Anjali K. M. De Silva Harald Riegel aalen university Aalen Germany Glasgow Caledonian university Glasgow UK

Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing technique, which allows production of highly complex solid metal parts with good mechanical properties, compared to conventionally manufactured parts. Nevertheless, the layer-by-layer fabrication process also offers several disadvantages, including a relatively high surface roughness depending on the shape of the component, its position and orientation during the fabrication process. This paper deals with investigations on the surface roughness reduction capability, and residual surface structures by laser polishing of LPBF AlSi10Mg parts under varying initial surface roughness in order to investigate the influence of the surface behavior and initial surface roughness to the achievable surface quality by laser polishing. Hereto test specimens with varying fabrication orientations regarding to the built platform are printed and further polished. Thereby the initial arithmetic roughness varies between 19.2 μm and 8.0 μm. It could be shown that the achievable surface roughness by laser polishing with continuous and pulsed laser radiation is increasing with rising initial roughness, but the relative roughness reduction is almost constant in the range of 95% - 97.5%. The analyzation of the residual roughness structures shows, that the main roughness differences is found in the middle and long structure wavelength regime, which are directly depending on the initial surface structures of 3D printing.

关键词： Additive Manufacturing Surface Roughness Aluminium AlSi10Mg Laser Polishing Fabrication Orientation

Hospital Employer Attractiveness Considering the Increasing Shortage of Skilled Medical Professionals—A German Review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Biosciences and Medicines 2016年第12期4卷 1-10页

作者： Joachim Merk Anke Rahmel SRH Fernhochschule The Mobile University Beruf Germany aalen university Aalen Germany

The main goal of this review is to give an overview of scientific publications concerning the employer attractiveness of German hospitals from the perspective of medical doctors in order to identify future research possibilities. After a summary of central problems concerning the German health sector and its current challenges, the study design behind the systematic content analysis as well as its criteria are presented. Selected results describe characteristics of expert literature for employer attractiveness in general, the attractiveness of German hospitals as employers (“hospital employer attractiveness” for short) as well as employer attractiveness from a medical doctor’s point of view. For each of these areas, focal points of research and main results are summarized and research gaps are pointed out.

关键词： Systematic Content Analysis Mainly German-Language Expert Literature Hospital Employer Attractiveness Medical Professionals

Optical imaging of post-embryonic zebrafish using multi orientation raster scan optoacoustic mesoscopy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2016年第1期5卷 336-341页

作者： Murad Omar Johannes Rebling Kai Wicker Tobias Schmitt-Manderbach Mathias Schwarz Jérôme Gateau Hérnan López-Schier Timo Mappes Vasilis Ntziachristos Chair for Biological Imaging Technische Universität MünchenMünchen D-81675Germany Institute for Biological and Medical Imaging Helmholtz Zentrum MünchenNeuherberg D-85764Germany Carl Zeiss AG Corporate Research and TechnologyJena D-07745Germany ESPCI Paris PSL Research UniversityCNRSINSERMInstitut LangevinParis F-75005France Research Unit Sensory Biology and Organogenesis Helmholtz Zentrum MünchenNeuherberg D-85764Germany Carl Zeiss Vision International GmbH Technology&InnovationAalen D-73430Germany

Whole-body optical imaging of post-embryonic stage model organisms is a challenging and long sought-after *** requires a combination of high-resolution performance and high-penetration ***(photoacoustic)mesoscopy holds great promise,as it penetrates deeper than optical and optoacoustic microscopy while providing high-spatial ***,optoacoustic mesoscopic techniques only offer partial visibility of oriented structures,such as blood vessels,due to a limited angular detection aperture or the use of ultrasound frequencies that yield insufficient *** introduce 3601 multi orientation(multi-projection)raster scan optoacoustic mesoscopy(MORSOM)based on detecting an ultra-wide frequency bandwidth(up to 160 MHz)and weighted deconvolution to synthetically enlarge the angular *** report unprecedented isotropic inplane resolution at the 9–17μm range and improved signal to noise ratio in phantoms and opaque 21-day-old *** find that MORSOM performance defines a new operational specification for optoacoustic mesoscopy of adult organisms,with possible applications in the developmental biology of adulthood and aging.

关键词： deconvolution development mesoscopy multiview optoacoustics photoacoustics

Exploring the Impact of Factors Affecting the Lifespan of HIVs/AIDS Patient’s Survival: An Investigation Using Advanced Statistical Techniques

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Endocrine and Metabolic Diseases 2023年第4期13卷 594-618页

作者： Christiana I. Ezeilo Edith U. Umeh Daniel C. Osuagwu Chrisogonus K. Onyekwere Department of Statistics Nnamdi Azikiwe University Awka Nigeria College of Business Missouri State University Springfield USA

This study investigates the impact of various factors on the lifespan and diagnostic time of HIV/AIDS patients using advanced statistical techniques. The Power Chris-Jerry (PCJ) distribution is applied to model CD4 counts of patients, and the goodness-of-fit test confirms a strong fit with a p-value of 0.6196. The PCJ distribution is found to be the best fit based on information criteria (AIC and BIC) with the smallest negative log-likelihood, AIC, and BIC values. The study uses datasets from St. Luke hospital Uyo, Nigeria, containing HIV/AIDS diagnosis date, age, CD4 count, gender, and opportunistic infection dates. Multiple linear regression is employed to analyze the relationship between these variables and HIV/AIDS diagnostic time. The results indicate that age, CD4 count, and opportunistic infection significantly impact the diagnostic time, while gender shows a nonsignificant relationship. The F-test confirms the model's overall significance, indicating the factors are good predictors of HIV/AIDS diagnostic time. The R-squared value of approximately 72% suggests that administering antiretroviral therapy (ART) can improve diagnostic time by suppressing the virus and protecting the immune system. Cox proportional hazard modeling is used to examine the effects of predictor variables on patient survival time. Age and CD4 count are not significant factors in the hazard of HIV/AIDS diagnostic time, while opportunistic infection is a significant predictor with a decreasing effect on the hazard rate. Gender shows a strong but nonsignificant relationship with decreased risk of death. To address the violation of the assumption of proportional hazard, the study employs an assumption-free alternative, aalen’s model. In the aalen model, all predictor variables except age and gender are statistically significant in relation to HIV/AIDS diagnostic time. The findings provide valuable insights into the factors influencing diagnostic time and survival of HIV/AIDS patients, which

关键词： Chris-Jerry Distribution Power Chris-Jerry Distribution Cox Proportional Hazard aalen’s Model Factors Affecting HIV/AIDS Patients CD4 Counts of HIV/AIDS Patients

An Additive-Multiplicative Cox-aalen Subdistribution Hazard Model for Competing Risks Data

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2019年第6期32卷 1727-1746页

作者： LI Wanxing LONG Yonghong Department of Statistics School of Mathematics and Information ScienceShaanxi Normal UniversityXi'an 710119China School of Mathematics Renmin University of ChinaBeijing 100872China

This paper proposes a flexible additive-multiplicative Cox-aalen hazard model which allows time-varying covariate effects for the subdistribution in a competing risks *** ted estimating equation approaches under an covariates-dependent adjusted weight by fitting the Cox proportional hazard model for the censoring distribution are established for inference on the model parametric and nonparametric *** addition,large number properties are presented and the finite sample behavior of the proposed estimators is evaluated through simulation studies,estimators from the proposed method perform satisfactorily on reduction of the *** authors apply our model to a competing risks data set from a tamoxifen trail for breast cancer study.

关键词： aalen's additive model competing risks cumulative incidence function estimating equation inverse probability of censoring weight proportional hazard function time-varying effects

CRISPR-mediated BnaIDAediting prevents silique shattering, floral organ abscission, and spreading of Sclerotinia sclerotiorum in Brassica napus

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Plant Communications 2022年第6期3卷 127-130页

作者： Rui Geng Yue Shan Lei Li Chun-Lin Shi Wei Zhang Jin Wang Rehman Sarwar Yi-Xuan Xue Yu-Long Li Ke-Ming Zhu Zheng Wang Li-Zhang Xu Reidunn B.aalen Xiao-Li Tan School of Life Sciences Jiangsu UniversityZhenjiang 212013China ANGENOVO 1414 VikenNorway Key Laboratory for Theory and Technology of Intelligent Agricultural Machinery and Equipment Jiangsu UniversityZhenjiang 212013China Department of Biosciences University of Oslo0316 OsloNorway

Dear Editor,Rapeseed(Brassica napus)oil is a major source of vegetable oil around the *** rot disease caused by the necrotrophic fungus Sclerotinia sclerotiorum and silique shattering during harvest are two major contributors to yield loss in ***(Zhang et al.,2021).Infection by *** occurs when ascospores land on detached petals where they germinate and form mycelia that ultimately infects the leaves(Ding et al.,2021).Consistent with this mode of infection,reduced damage from stem rot has been achieved by generating apetalous rapeseed that are resistant to petal-mediated infection(Yu et al.,2016).We propose that preventing petal shedding should also reduce leaf ***,attached floral organs will promote rapeseed flower tourism and provide an additional economic benefit.

关键词： attached generating organs

A class of transformation rate models for recurrent event data

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2016年第11期59卷 2227-2244页

作者： ZHANG Hu YANG QingLong QU LianQiang School of Statistics and Mathematics Zhongnan University of Economics and Law Institute of Applied Mathematics Academy of Mathematics and Systems ScienceChinese Academy of Sciences

Recurrent event data frequently occur in longitudinal studies, and it is often of interest to estimate the effects of covariates on the recurrent event rate. This paper considers a class of semiparametric transformation rate models for recurrent event data, which uses an additive aalen model as its covariate dependent baseline. The new models are flexible in that they allow for both additive and multiplicative covariate effects,and some covariate effects are allowed to be nonparametric and time-varying. An estimating procedure is proposed for parameter estimation, and the resulting estimators are shown to be consistent and asymptotically normal. Simulation studies and a real data analysis demonstrate that the proposed method performs well and is appropriate for practical use.

关键词： aalen model estimating equations recurrent event data time-varying coefficients transformation rate models

Nelson-aalen and Kaplan-Meier Estimators in Competing Risks

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics 2014年第4期5卷 765-776页

作者： Didier Alain Njamen-Njomen Joseph Ngatchou-Wandji Department of Mathematics and Computer Sciences Faculty of Sciences University of Maroua Maroua Cameroon Department of Mathematics Faculty of Sciences University of Yaounde 1 Yaounde Cameroon university of Lorraine Lorraine France

In this paper, stochastic processes developed by aalen [1]?[2] are adapted to the Nelson-aalen and Kaplan-Meier?[3] estimators in a context of competing risks. We focus only on the probability distributions of complete downtime individuals whose causes are known and which bring us to consider a partition of individuals into sub-groups for each cause. We then study the asymptotic properties of nonparametric estimators obtained.

关键词： Censored Data Counting Process Competitive Risk Non-Parametric Estimators The Cumulative Incidence Function Risk Function Specific Cause Conditional Distribution Function

Asymptotic Normality of the Nelson-aalen and the Kaplan-Meier Estimators in Competing Risks

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics 2019年第7期10卷 545-560页

作者： Didier Alain Njamen Njomen Department of Mathematics and Computer Science Faculty of Science University of Maroua Maroua Cameroon

This paper studies the asymptotic normality of the Nelson-aalen and the Kaplan-Meier estimators in a competing risks context in presence of independent right-censorship. To prove our results, we use Robelledo’s theorem which makes it possible to apply the central limit theorem to certain types of particular martingales. From the results obtained, confidence bounds for the hazard and the survival functions are provided.

关键词： Censored Data Right-Censoring Counting Process Competing Risks Nelson-aalen and Kaplan-Meier Estimators Asymptotic Properties of Estimators Confidence Bands