检索结果-南通市图书馆

Journal of Hydrodynamics 2024年第1期36卷 184-201页

作者： xiao-qi Jia Shuai-kang Zhang Zu-chao Zhu Key Laboratory of Fluid Transmission Technology of Zhejiang Province Zhejiang Sci-Tech UniversityHangzhou310018China

To reveal the cavitation forms of tip leakage vortex(TLV)of the axial flow pump and the flow mechanism of the flow field,this research adopts the partially-averaged Navier-Stokes(PANS)model to simulate the cavitation values of an axial flow pump,followed by experimental validation.The experimental result shows that compared with the shear stress transport(SST)k-ωmodel,the PANS model significantly reduces the eddy viscosity of the flow field to make the vortex structure clearer and allow the turbulence scale to be more robustly analyzed.The cavitation area within the axial flow pump mainly comprises of TLV cavitation,clearance cavitation and tip leakage flows combined effect of triangular cloud cavitation formed.The formation and development of cavitation are accompanied by the formation and evolution of vortex,and variations in vortex structure also generate and promote the development of cavitation.In addition,an in-depth analysis of the relationship between the turbulent kinetic energy(TKE)transport equation and cavitation patterns was also conducted,finding that the regions with relatively high TKE are mainly distributed around gas/liquid boundaries with serious cavitation and evident gas-liquid change.This phenomenon is mainly attributed to the combined effect of the pressure action term,stress diffusion term and TKE production term.

关键词： Cavitation axial flow pump tip leakage vortex(TLV) partially-averaged Navier-Stokes(PANS)model turbulent kinetic energy(TKE)

Quantitative Analysis of Seeing with Height and Time at Muztagh-Ata Site Based on ERA5 Database

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第1期24卷 87-95页

作者： xiao-qi Wu Cun-Ying xiao Ali Esamdin Jing Xu Ze-Wei Wang Luo xiao Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Department of Astronomy Beijing Normal UniversityBeijing 100875China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China

Seeing is an important index to evaluate the quality of an astronomical site.To estimate seeing at the Muztagh-Ata site with height and time quantitatively,the European Centre for Medium-Range Weather Forecasts reanalysis database(ERA5)is used.Seeing calculated from ERA5 is compared consistently with the Differential Image Motion Monitor seeing at the height of 12 m.Results show that seeing decays exponentially with height at the Muztagh-Ata site.Seeing decays the fastest in fall in 2021 and most slowly with height in summer.The seeing condition is better in fall than in summer.The median value of seeing at 12 m is 0.89 arcsec,the maximum value is1.21 arcsec in August and the minimum is 0.66 arcsec in October.The median value of seeing at 12 m is 0.72arcsec in the nighttime and 1.08 arcsec in the daytime.Seeing is a combination of annual and about biannual variations with the same phase as temperature and wind speed indicating that seeing variation with time is influenced by temperature and wind speed.The Richardson number Ri is used to analyze the atmospheric stability and the variations of seeing are consistent with Ri between layers.These quantitative results can provide an important reference for a telescopic observation strategy.

关键词： site testing atmospheric effects methods:data analysis telescopes Earth

Ordered Bicontinuous Network Structures Regulated by Orientational Interactions in a Rod-Coil Block Copolymer

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第5期42卷 636-642,I0008页

作者： xiao-Lin Lyu Shi-Chu Yang An-qi xiao Ping-Ping Hou Wei Zhang Hong-Bing Pan Zhi-Hao Shen Xing-He Fan qi-Feng Zhou Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China Key Laboratory of Advanced Materials Technologies International(HongKong Macao and Taiwan)Joint Laboratory on Advanced Materials TechnologiesCollege of Materials Science and EngineeringFuzhou UniversityFuzhou350108China

The rich phase behavior of block copolymers(BCPs)has drawn great attention in recent years.However,the double diamond(DD)phase is rarely obtained because of the competition between the minimization of interfacial energy and packing frustration.Here,a rod-coil BCP containing mesogen-jacketed liquid crystalline polymer is designed to acquire ordered bicontinuous network nanostructures.The reduction of internal energy originating from the orientational interaction among the rod blocks can compensate for the free energy penalty of packing frustration to stabilize the DD structure.The resulting BCP can also experience lamellae-to-DD and double gyroid-to-lamellae transitions by changing the annealing temperature.These results make the rod-coil BCP an excellent candidate for the self-assembly of ordered network structures,demonstrating great potential in nanopatterning and metamaterials.

关键词： Block copolymer Rod-coil Ordered bicontinuous phase Double diamond Double gyroid

Effects of Hydrogen Charging Time and Pressure on the Hydrogen Embrittlement Susceptibility of X52 Pipeline Steel Material

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 293-307页

作者： Hong-Jiang Wan xiao-qi Wu Hong-Liang Ming Jian-qiu Wang En-Hou Han School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering Northeastern UniversityShenyang110819China Institute of Corrosion Science and Technology Guangzhou510530China

The effects of hydrogen charging time and pressure on the hydrogen embrittlement(HE)susceptibility of X52 pipeline steel material are studied by slow strain rate tensile tests.The fracture morphologies of the specimens are observed by scanning electron microscopy.The HE susceptibility of the X52 pipeline steel material increases with an increase in both hydrogen charging time and hydrogen pressure.At a charging time of 96 h,the HE susceptibility index reaches 45.86%,approximately 3.6 times that at a charging time of 0 h.Similarly,a charging pressure of 4 MPa results in a HE susceptibility index of 31.61%,approximately 2.5 times higher than that at a charging pressure of 0.3 MPa.

关键词： Hydrogen embrittlement X52 pipeline steel material Tubular specimen Hydrogen charging time Hydrogen charging pressure

Predicting short-term major postoperative complications in intestinal resection for Crohn’s disease:A machine learning-based study

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 Gastrointestinal Surgery 2024年第3期16卷 717-730页

作者： Fang-Tao Wang Yin Lin xiao-qi Yuan Ren-Yuan Gao xiao-Cai Wu Wei-Wei Xu Tian-qi Wu Kai Xia Yi-Ran Jiao Lu Yin Chun-qiu Chen Diagnostic and Treatment Center for Refractory Diseases of Abdomen Surgery Shanghai Tenth People’s HospitalTongji University School of MedicineShanghai 200072China

BACKGROUND Due to the complexity and numerous comorbidities associated with Crohn’s disease(CD),the incidence of postoperative complications is high,significantly impacting the recovery and prognosis of patients.Consequently,additional stu-dies are required to precisely predict short-term major complications following intestinal resection(IR),aiding surgical decision-making and optimizing patient care.AIM To construct novel models based on machine learning(ML)to predict short-term major postoperative complications in patients with CD following IR.METHODS A retrospective analysis was performed on clinical data derived from a patient cohort that underwent IR for CD from January 2017 to December 2022.The study participants were randomly allocated to either a training cohort or a validation cohort.The logistic regression and random forest(RF)were applied to construct models in the training cohort,with model discrimination evaluated using the area under the curves(AUC).The validation cohort assessed the performance of the constructed models.RESULTS Out of the 259 patients encompassed in the study,5.0%encountered major postoperative complications(Clavien-Dindo≥III)within 30 d following IR for CD.The AUC for the logistic model was 0.916,significantly lower than the AUC of 0.965 for the RF model.The logistic model incorporated a preoperative CD activity index(CDAI)of≥220,a diminished preoperative serum albumin level,conversion to laparotomy surgery,and an extended operation time.A nomogram for the logistic model was plotted.Except for the surgical approach,the other three variables ranked among the top four important variables in the novel ML model.CONCLUSION Both the nomogram and RF exhibited good performance in predicting short-term major postoperative complic-ations in patients with CD,with the RF model showing more superiority.A preoperative CDAI of≥220,a di-minished preoperative serum albumin level,and an extended operation time might be the most crucial variables.The findings of this study can assist clinicians in

关键词： Crohn’s disease Postoperative complications Nomogram Random forest Intestinal resection

Advances in Polymethine Dyes for Near-Infrared Organic Photodiodes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2023年第11期41卷 1399-1416页

作者： Jin He qi xiao Ming Shao Zhong'an Li Key Laboratory for Material Chemistry of Energy Conversion and Storage Ministry of EducationSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhanHubei430074 China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhanHubei430074 China

Near-infrared organic photodiodes (NIR OPDs) have tremendous potential in industrial, military, and scientific applications, due to their unique features of lightweight, low toxicity, high structural flexibility, cooling-system-free, etc. However, the overall performance of currently available NIR OPDs still lags behind the commercial inorganic photodetectors, ascribed to the critical challenge of realizing organic semiconductors with sufficiently low optical bandgap and excellent optoelectronic properties simultaneously. Among various types of NIR-absorbing organic semiconductors, polymethine dyes not only possess advantages of simple synthesis and structural diversity, but also show fascinating optical and aggregation features in the solid state, making them attractive material candidates for NIR OPDs. In this review, after a brief introduction of NIR OPDs and polymethine dyes, we comprehensively summarize the advances of polymethine dyes for broadband and narrowband NIR OPDs, and further introduce their applications in all-organic optical upconversion devices and photoplethysmography sensors. In particular, the relationship between the chemical structure and the aggregation behaviors of polymethine dyes and the device performance is carefully discussed, providing some important molecular insights for developing high performance NIR OPDs.

关键词： Near-infrared organic photodiodes Dyes/Pigments Polymethine dyes Aggregation Optical upconversion device Photoplethysmography sensor Photoelectric performances

MoS2 as a cocatalyst applied in advanced oxidation processes for enhancing degradation of organic pollutants: a 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

Tungsten 2024年第3期6卷 473-487页

作者： Ming-Hao Fan Cong-Hui Wang Xiang Yu Jun Ding Ao-qi xiao Yue Li Wei-Ya Huang School of Material Science and Engineering Henan Polytechnic University School of Chemical and Printing-Dyeing Engineering Henan International Joint Laboratory of Rare Earth Composite Materials Henan University of Engineering School of Chemistry and Chemical Engineering Jiangxi University of Science and Technology Department of Chemical and Environmental Engineering University of Cincinnati

Fenton technology,as a typical advanced oxidation processes（AOPs）,can generate reactive oxygen species（ROS） of strong oxidation capacity to degrade organic pollutants,which has attracted wide attention.However,it is accompanied by the slow Fe3+/Fe2+cycle rate,easy to generate iron sludge and so on.Recently,it has been proven that the inorganic cocatalysts represented by MoS2can effectively solve the above problems.Meanwhile,MoS2can accelerate the activation of peroxy mono sulfate（PMS） and peroxodisulfate（PDS） by Fe2+.In this paper,MoS2as the cocatalyst in H2O2+Fe2+,PMS+Fe2+and PDS+Fe2+were comprehensively reviewed.Specially,the cycling processes of Fe3+/Fe2+in different systems,the cocatalytic effect of MoS2by the exposed active sites,the ROS generation mechanism as well as the microscopic mechanism during the reaction were elaborated emphatically.The results indicate that the reductive active sites on the surface of MoS2can promote the regeneration of Fe2+through the cycle between Fe3+/Fe2+and Mo4+/Mo5+/Mo6+.Thus,ROS such as ·OH,SO4·-and1O2with strong oxidizing property can be produced to improve the degradation efficiency of organic pollutants.At last,the challenges and developments of MoS2cocatalysts in AOPs for practical applications were prospected.This review contributes to a deeper understanding of the cocatalytic effect of two-dimensional metal sulfides in AOPs and facilitates their industrial application.

关键词： Cocatalyst Fenton reaction Degradation of organic pollutant Molybdenum disufide Reactive oxygen species

Experimental quantum state compression from two identical qubits to a qutrit

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 1-5页

作者： qiao Xu Lin-Xiang Zhou Tian-Feng Feng Shang-Feng qiu Si-Wu Li Wu-Ji Zhang Hui Luo xiao-qi Zhou State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics Sun Yat-sen UniversityGuangzhou 510000China Hefei National Laboratory Hefei 230088China

In the realm of modern information technology,data compression technology occupies a pivotal position.With advancements in quantum information technology,the need to compress large-scale qubits ensembles has become urgent,aiming to reduce the demand on quantum storage resources.However,existing quantum state compression schemes generally face a limitation:the particles before and after compression must reside in the same dimensional space.In specific scenarios,compressing qubits into particles of higher dimensions not only enhances the efficiency of quantum state compression but also further reduces the usage of quantum storage resources.Here we experimentally demonstrated a quantum state compression between particles of different dimensions,successfully compressing two qubits into a single qutrit.The average fidelity of the resulting qutrit with the ideal quantum state is 0.8835.Our study may have potential applications in future quantum information,such as increasing quantum communication bandwidth and reducing storage resource consumption in quantum computing.

关键词： quantum state compression quantum information technology optics

中国交通运输碳排放强度时空交互特征及跃迁机制

在线全文

学校读者我要写书评

暂无评论

环境科学 2024年第6期45卷 3433-3445页

作者：李健刘舒琪王晓祺天津理工大学管理学院天津300384 天津大学管理与经济学部天津300372

采取多种空间分析的方法,对2002~2020年交通运输业碳排放强度的时空交互特征进行剖析,通过得到的时空跃迁类型与面板分位数模型进行嵌套来探究其跃迁机制,最后根据不同的跃迁机制引入地理探测器模型来考察影响交通运输业碳排放强度的不... 详细信息

采取多种空间分析的方法,对2002~2020年交通运输业碳排放强度的时空交互特征进行剖析,通过得到的时空跃迁类型与面板分位数模型进行嵌套来探究其跃迁机制,最后根据不同的跃迁机制引入地理探测器模型来考察影响交通运输业碳排放强度的不同因素之间的交互作用效应.结果表明:①中国30个省区的交通运输业碳排放强度整体呈波动下降态势,在空间上的聚集水平也相对稳定.②ESTDA的时空交互特征表明,西北地区和周边邻接空间单位的关系不稳定,变化和波动较大.而东部沿海城市等经济发达地区已经形成了成熟的交通运输网络,因此局部空间格局也相对稳定,但仍有部分地区存在时空竞争性.③交通运输业碳排放强度时空跃迁可分为4类驱动或制约模式(人口-经济-城镇化制约模式;人口-经济-城镇化-设施制约模式;技术-消费-产业驱动模式和技术-产业-规制驱动模式).大部分省份受低分位制约和高分位驱动两种模式的影响,仅有少部分省份受高分位制约和低分位驱动的作用影响,且绝大多数属于西北或西南地区.④根据得出的交通运输业碳排放强度跃迁机制进一步引入地理探测器模型,注重多因子的协调发展,加强区域间协同治理.

关键词：交通运输业碳排放强度时空交互跃迁机制分位数回归地理探测器

Influence of Built Environment in Hygienic City in China on Self-rated Health of Residents

在线全文

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 2022年第12期35卷 1126-1132页

作者： ZHENG Wen Jing qi xiao YAO Hong Yan LIU Jian Jun YU Shi Cheng ZHANG Tao Office of Epidemiology Chinese Center for Disease Control and PreventionBeijing 102206China Chinese Center for Disease Control and Prevention Beijing 102206China Aerospace Center Hospital Beijing 100049Chin

Objective To assess the subjective perception of residents on the built environment in hygienic cities and its relation to the self-rated health(SRH)status of residents,providing a basis for a better promotion on construction of health-supportive environments.Methods The online survey was adopted with the respondents recruited from residents living in Chaoyang District of Beijing in January 2021.With SRH level as the dependent variable,two-category logistic regression analysis was conducted to analyze the impact of the built environment in hygienic cities on the SRH status of residents.Results A total of 1,357 respondents were enrolled in this study.After controlling confounding factors,four aspects in the built environment in hygienic cities were detected remarkable influences on the SRH level of residents,including enough green space in the living area[odds ratio(OR)=1.395,95%confidence interval(95%CI):1.055–1.845],clean and hygienic living environment(OR=1.472,95%CI:1.107–1.956),residents’confidence in drinking water safety in the living area(OR=1.856,95%CI:1.354–2.544)and residents’confidence in food safety in the living area(OR=1.405,95%CI:1.027–1.921).Conclusion Regarding city construction,the government should focus more on the subjective perception of residents on built environments to build a supportive environment benefiting the health of residents.

关键词： Hygienic city Built environment Self-rated health