检索结果-南通市图书馆

Effects of Bifidobacterium lactis BLa80 on fecal and mucosal flora and stem cell factor/c-kit signaling pathway in simulated microgravity rats

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2025年第1期31卷 93-109页

作者： Ping zhang Ying Zhu Pu Chen Tong Zhou Zhe-Yi Han jun Xiao Jian-Feng Ma Wen Ma peng Zang Ying Chen Graduate School Hebei North UniversityZhangjiakou 075000Hebei ProvinceChina Key Laboratory of Aerospace Nutrition and Food Engineering China Astronaut Research and Training CenterBeijing 100094China Department of Gastroenterology The Air Force Medical CenterBeijing 100142China Department of Blood Transfusion Air Force Medical CenterBeijing 100142China

BACKGROUND Simulated microgravity environment can lead to gastrointestinal motility *** pathogenesis of gastrointestinal motility disorders is closely related to the stem cell factor(SCF)/c-kit signaling pathway associated with intestinal flora and Cajal stromal ***,intestinal flora can also affect the regulation of SCF/c-kit signaling pathway,thus affecting the expression of Cajal stromal *** cells are the pacemakers of gastrointestinal *** To investigate the effects of Bifidobacterium lactis(***)BLa80 on the intestinal flora of rats in simulated microgravity and on the gastrointestinal motility-related SCF/c-kit *** The internationally recognized tail suspension animal model was used to simulate the microgravity environment,and 30 rats were randomly divided into control group,tail suspension group and drug administration tail suspension group with 10 rats in each group for a total of 28 *** tail group was given *** BLa80 by intragastric administration,and the other two groups were given water intragastric administration,the concentration of intragastric administration was 0.1 g/mL,and each rat was 1 mL/***&eosin staining was used to observe the histopathological changes in each segment of the intestine of each group,and the expression levels of SCF,c-kit,extracellular signal-regulated kinase(ERK)and p-ERK in the gastric antrum of each group were detected by Western blotting and *** fecal flora and mucosal flora of rats in each group were detected by 16S *** Simulated microgravity resulted in severe exfoliation of villi of duodenum,jejunum and ileum in rats,marked damage,increased space between villi,loose arrangement,shortened columnar epithelium of colon,less folds,narrower mucosal thickness,reduced goblet cell number and crypts,and significant improvement after probiotic *** microgravity reduced the expressions of SCF and c-kit,and increased the express

关键词： Simulated microgravity Rat Intestinal flora Gastrointestinal motility Stem cell factor/c-kit signaling pathway

Substrate Effect on Microstructure and Performance of LTHVOF Sprayed Copper Coatings

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

稀有金属材料与工程 2012年第S1期41卷 380-383页

作者： zha Bailin Yuan Xiaojing zhan jun Jiang peng Xian Res Inst Hitech Xian 710025 Peoples R China

The performance of copper coatings fabricated on three substrates by LTHVOF spraying process was *** shows that substrate material has little effect on phase composition of coatings,and there is no oxide in the three coatings *** coatings are dense,and demonstrate little difference on the microstructure of the inner part of the ***,microstructure of bonding area between coating and substrate shows big difference,copper coatings bonds compacter on soft substrate aluminum than hard substrate *** strength of coatings sprayed on the soft substrate is higher than that on the hard *** analysis of fracture surface shows that strong mechanical alloying phenomena when copper particles deposited on aluminum *** average bonding strength of copper coatings on 1Cr18Ni9Ti,45#steel and LY12 is relatively 18.83,17.49 and 32.14 *** have strong effect on microstructure and bonding strength,but little on phase composition...

关键词： bonding strength coating microstructure

Geometric Error Identification of Gantry-Type CNC Machine Tool Based on Multi-Station Synchronization Laser Tracers

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第2期37卷 150-162页

作者： jun zha Huijie zhang School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China Xi’an Jiaotong University Suzhou Academy Suzhou 215123China

Laser tracers are a three-dimensional coordinate measurement system that are widely used in industrial *** propose a geometric error identification method based on multi-station synchronization laser tracers to enable the rapid and high-precision measurement of geometric errors for gantry-type computer numerical control(CNC)machine *** method also improves on the existing measurement efficiency issues in the single-base station measurement method and multi-base station time-sharing measurement *** consider a three-axis gantry-type CNC machine tool,and the geometric error mathematical model is derived and established based on the combination of screw theory and a topological analysis of the machine kinematic *** four-station laser tracers position and measurement points are realized based on the multi-point positioning principle.A self-calibration algorithm is proposed for the coordinate calibration process of a laser tracer using the Levenberg-Marquardt nonlinear least squares method,and the geometric error is solved using Taylor’s first-order linearization *** experimental results show that the geometric error calculated based on this modeling method is comparable to the results from the Etalon laser *** a volume of 800 mm×1000 mm×350 mm,the maximum differences of the linear,angular,and spatial position errors were 2.0μm,2.7μrad,and 12.0μm,respectively,which verifies the accuracy of the proposed *** research proposes a modeling method for the precise measurement of errors in machine tools,and the applied nature of this study also makes it relevant both to researchers and those in the industrial sector.

关键词： Multi-point positioning Multi-station synchronization CNC machine tool Geometric error Error separation

Multi-dimensional controllability analysis of precision ball bearing integrity

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2023年第4期11卷 682-693页

作者： Lai Hu jun zha Wei-Hua zhao Xiao-Fei peng Yao-Long Chen School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an710049People’s Republic of China State Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an710054People’s Republic of China Luoyang Bearing Science and Technology Co. Ltd.Luoyang471039HenanPeople’s Republic of China

Many factors affect the integrity of precision ball *** this study,the multi-dimensional controllability of precision ball bearings produced in different company brands(bearing A and bearing B)were studied and *** geometric errors(flatness,parallelism,roundness and cylindricity of inner and outer rings,roundness,groove and roughness of inner and outer rings)and vibration errors of bearings were ***,the residual stress,residual austenite content,element content ratio,metamorphic layer and temperature-vibration displacement coupling test were also *** on the above analysis conclusion,the bearing fatigue life test was carried out for 2150 *** reliability of the conclusion is proved again as *** the residual austenite content in the raceway of precision ball bearing is 10%,the axial residual stress is 877.4 MPa;the tangential residual stress is 488.1 MPa;the carbon content is 6%;the test temperature of bearing is the lowest;and the service life is prolonged.

关键词： Precision ball bearing Controllability Geometric errors Carbon content Residual austenite Residual stress

Study on creep-fatigue damage evaluation for advanced 9%–12% chromium steels under stress controlled cycling

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2011年第2期24卷 148-154页

作者： peng zha O Fuzhen XUAN Key Laboratory of Safety Science of Pressurized System Ministry of Education School of Mechanical andPower Engineering East China University of Science and Technology Shanghai 200237 China

Creep-fatigue interaction is one of the main damage mechanisms in high temperature plants and their components. Assessment of creep-fatigue properties is of practical importance for design and operation of high temperature components. However, the standard evaluation techniques, i.e. time fraction rule and ductility exhaustion one have limitations in accounting for the effects of control mode on the cyclic deformations. It was found that conventional linear cumulative damage rule failed in accurately evaluating the creep-fatigue life under stress controlled condition. The calculated creep damages by time fraction rule were excessively high, which led to overly conservative prediction of failure lives. In the present study, it was suggested that such over estimation of creep damage was mainly caused by anelastic strain upon stress loading. For precise assessment under conditions of stress control, a modified creep damage model accounting for the effect of anelastic creep was proposed. The assessments of creep fatigue data under stress controlled condition were performed with the new approach developed in this paper for a rotor material and a boiler material used in ultra supercritical power plants. It was shown that a more moderate amount of creep damage was obtained by the new model, which gave better predictions of failure life.

关键词： Creep-fatigue Creep damage 9%–12%Cr steels Stress control Time fraction rule

Theoretical analysis and application of polymer-matrix field grading materials in HVDC cable terminals

在线全文

学校读者我要写书评

暂无评论

High Voltage 2017年第1期2卷 39-46页

作者： peng Han jun-Wei zha Si-Jiao Wang Zhi-Min Dang Department of Polymer Science and Engineering University of Science and Technology BeijingBeijing 100083People’s Republic of China State Key Laboratory of Power System and Department of Electrical Engineering Tsinghua UniversityBeijing 100084People’s Republic of China

The distortion and uneven distribution of electric field in high-voltage direct current(HVDC)terminal insulator is the key problem for stable running of the power transmission *** flexible materials filled polymer-matrix composites with non-linear conductivity have also been considered to modify the distribution of electric field in cable *** factors having influence on the non-linear conductivity will be analysed in this review.

关键词： field conductivity matrix

Recent Progress on Aeroelasticity of High-Performance Morphing UAVs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2022年第10期133卷 1-29页

作者： Binbin Lv jun zha Kaichun Zeng Hongtao Guo Li Yu peng zhang Institute of High Speed Aerodynamics China Aerodynamics Research and Development CenterMianyang621000China

The high-performance morphing aircraft has become a research focus all over the *** morphing aircraft,unlike regular unmanned aerial vehicles(UAVs),has more complicated aerodynamic characteristics,making itmore difficultto conduct its design,model analysis,and *** paper reviews the recent process and the current status of aeroelastic issues,numerical simulations,and wind tunnel test of morphing *** evaluation of aerodynamic characteristics,mechanism,and relevant unsteady dynamic aerodynamicmodeling throughout the morphing process are the primary technological bottlenecks formorphing *** unstable aerodynamic forces have a significant impact on the aircraft handling characteristics,control law design,and flight *** the past,the structural analysis of morphing aircrafts,flight dynamics modeling,computational mesh morphing technology,and aerodynamic calculation were performed in promoting the development of next generation UAVs,with nonlinear dynamic challenges includingtransonic aeroelastic problems and high angle of attack aeroelastic *** present,many facets of these difficulties,together with the accompanying numerical simulation studies,remain *** addition,wind tunnel experiments face significant challenges in the dynamic morphing ***,dynamic unsteady aerodynamic characteristics in the continuous morphing process still need to be verified by more related experiments.

关键词： Morphing aircraft aeroelasticity numerical simulation wind tunnel test

Policy iteration based Q-learning for linear nonzero-sum quadratic differential games

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(Information Sciences) 2019年第5期62卷 195-213页

作者： Xinxing LI Zhihong peng Li LIANG Wenzhong zha School of Automation Beijing Institute of Technology State Key Laboratory of Intelligent Control and Decision of Complex System Information Science Academy China Electronics Technology Group Corporation

In this paper, a policy iteration-based Q-learning algorithm is proposed to solve infinite horizon linear nonzero-sum quadratic differential games with completely unknown dynamics. The Q-learning algorithm, which employs off-policy reinforcement learning(RL), can learn the Nash equilibrium and the corresponding value functions online, using the data sets generated by behavior policies. First, we prove equivalence between the proposed off-policy Q-learning algorithm and an offline PI algorithm by selecting specific initially admissible polices that can be learned online. Then, the convergence of the off-policy Qlearning algorithm is proved under a mild rank condition that can be easily met by injecting appropriate probing noises into behavior policies. The generated data sets can be repeatedly used during the learning process, which is computationally effective. The simulation results demonstrate the effectiveness of the proposed Q-learning algorithm.

关键词： adaptive dynamic programming ADP Q-learning reinforcement learning RL linear nonzerosum quadratic differential games policy iteration PI off-policy

Photothermal-photocatalytic thin-layer flow system for synergistic treatment of wastewater

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2023年第11期63卷 120-129页

作者： Zhongjiao zha jun Wu Shaoping Tong Xuebo Cao College of Chemical Engineering State Key Laboratory Breeding Base of Green Chemistry-Synthesis TechnologyZhejiang University of TechnologyHangzhou 310014China College of Biological Chemical Sciences and EngineeringJiaxing UniversityJiaxing 314001China College of Advanced Materials Engineering Jiaxing Nanhu UniversityJiaxing 314001China

The integration of the photocatalytic effect into solar steam is highly desirable for addressing freshwater shortages and water ***,a ternary film structure for the adsorption and photothermal and photocatalytic treatment of wastewater was designed by combining the technique of self-assembled carbon nano paper with a nitrogen composite titanium dioxide(N-TiO_(2))deposited on the surface of carbon nanotubes(CNT)using polyvinylidene fluoride(PVDF)as a *** photogeneration of reactive oxygen species can be promoted by rapid oxygen diffusion at the three-phase interface,whereas the interfacial photothermal effect promotes subsequent free radical reactions for the degradation of rhodamine B(93%).The freshwater evaporation rate is 1.35 kg·m^(-2)·h^(-1)and the solar-to-water evaporation efficiency is 94%.Importantly,the N-TiO_(2)/CNT/PVDF(N-TCP)film not only effectively resists mechanical damage from the environment and maintains structural integrity,but can also be made into a large film for outdoor experiments in a large solar energy conversion device to collect fresh water from polluted water and degrade organic dyes in source water simultaneously,opening the way for applications in energy conversion and storage.

关键词： Wastewater disposal Solar-driven distill Thin-layer flow Clean water production Ternary film