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Unsteady flow structures in the tip region for a centrifugal compressor impeller before rotating stall

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Science China(Technological Sciences) 2017年第6期60卷 924-934页

作者： zhao HuiJing WANG ZhiHeng xi Guang School of Energy and Power Engineering Xi 'an Jiaotong University Xi'an 710049 China

To get an insight into the occurrence and the mechanism of flow unsteadiness in the tip region of centrifugal compressor impellers, the flow in Krain’s impeller is investigated by using both steady and unsteady RANS solver techniques. It is found that the flow unsteadiness on the pressure side is much stronger than that on the suction side. The periodical frequency of the unsteady flow is around half of the blade passing frequency. The originating mechanism of the flow unsteadiness is illustrated with the time-dependent tip leakage flow and blade loading at the tip region. Due to the blockage caused by the joint effects of broken-downed tip leakage vortex, separated fluids and tip leakage flow at downstream, a low pressure region is formed on the pressure side, consequently the blade loadings is altered. In turn, the changed blade loadings will alter the intensity of tip leakage flow. Such alternative behavior finally results in the periodic process. By comparing the calculated flow field in the cases of single-passage and four-passage models, it is confirmed that the investigated flow unsteadiness is confined in each single passage, as no phase differences are found in the model of four passages. This is different from the situation in axial compressor when the rotating instability is encountered. The flow unsteadiness only occurs at the working conditions with small mass flow rates, and the oscillation intensity will be enhanced with the decrease of mass flow rate. When the mass flow rate is too small, the flow unsteadiness in a single passage may trigger rotating stall, as the disturbance propagates in the circumferential direction.

关键词： centrifugal compressor impeller flow unsteadiness tip leakage flow blade loading

Surface tension of liquid metal： role, mechanism and application

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Frontiers in Energy 2017年第4期11卷 535-567页

作者： xi zhao Shuo XU Jing LIU Beijing Key Lab of CryoBiomedical Engineering and Key Lab of Cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China Beijing Key Lab of CryoBiomedical Engineering and Key Lab of Cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences Department of Biomedical Engineering School of Medicine Tsinghua University Beijing 100084 China

Surface tension plays a core role in dominating various surface and interface phenomena. For liquid metals with high melting temperature, a profound understanding of the behaviors of surface tension is crucial in industrial processes such as casting, welding, and solidification, etc. Recently, the room temperature liquid metal （RTLM） mainly composed of gallium-based alloys has caused widespread concerns due to its increasingly realized unique virtues. The surface properties of such materials are rather vital in nearly all applications involved from chip cooling, thermal energy harvesting, hydrogen generation, shape changeable soft machines, printed electronics to 3D fabrication, etc. owing to its pretty large surface tension of approximately 700 mN/m. In order to promote the research of surface tension of RTLM, this paper is dedicated to present an overview on the roles and mechanisms of surface tension of liquid metal and summarize the latest progresses on the understanding of the basic knowledge, theories, influencing factors and experimental measure- ment methods clarified so far. As a practical technique to regulate the surface tension of RTLM, the fimdamental principles and applications of electrowetting are also interpreted. Moreover, the unique phenomena of RTLM surface tension issues such as surface tension driven self- actuation, modified wettability on various substrates and the functions of oxides are discussed to give an insight into the acting mechanism of surface tension. Furthermore, future directions worthy of pursuing are pointed out.

关键词： surface tension liquid metal soft machine,printed electronics electrowetting self-actuation

基于电商平台类型的制造商产品组合和渠道选择决策

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物流科技 2025年第1期48卷 39-44页

作者：赵琳郎骁江苏科技大学经济管理学院江苏镇江212000

分别考虑仅在综合电商平台销售产品、仅在直播电商平台销售产品的两种情形,探讨制造商进入线上渠道时,应当如何做出产品组合和渠道选择的联合决策,并分析制造商的最优价格和利润会受到哪些因素的影响。结果表明:两种情形下制造商的最优... 详细信息

分别考虑仅在综合电商平台销售产品、仅在直播电商平台销售产品的两种情形,探讨制造商进入线上渠道时,应当如何做出产品组合和渠道选择的联合决策,并分析制造商的最优价格和利润会受到哪些因素的影响。结果表明:两种情形下制造商的最优产品组合取决于不同平台限制下的最大产品种类数量,最优渠道选择则取决于不同平台下的平台费用比例、单位产品利润以及固定成本的相对大小。不论制造商选择哪种平台渠道,消费者退货成本的增加均会降低产品价格,线上购买匹配率的增加均会提高制造商自身利润;此外,单位运营成本是影响制造商最优价格和利润的核心因素。

关键词：电商平台类型产品组合定价渠道选择

Silicon-based decoder for polarization-encoding quantum key distribution

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Chip 2023年第1期2卷 45-50页

作者： Yongqiang Du Xun Zhu xin Hua Zhengeng zhao xiao Hu Yi Qian xi xiao Kejin Wei Guangxi Key Laboratory for Relativistic Astrophysics School of Physical Sci-ence and TechnologyGuangxi UniversityNanning 530004China National In-formation Optoelectronics Innovation Center(NOEIC) Wuhan 430074China State Key Laboratory of Optical Communication Technologies and Networks China Information and Communication Technologies Group Corporation(CICT)Wuhan 430074China

Silicon-based polarization-encoding quantum key distribution(QKD)has been extensively studied due to its advantageous characteris-tics of its low cost and ***,given the difficulty of fabricating polarized independent components on the chip,previ-ous studies have only adopted off-chip devices to demodulate the quantum states or perform polarization *** the cur-rent work,a fully chip-based decoder for polarization-encoding QKD was *** chip realized a polarization state analyzer and compensated for the BB84 protocol without the requirement of additional hardware,which was based on a polarization-to-path conversion method utilizing a polarization *** chip was fabricated adopting a standard silicon photonics foundry,which was of a compact design and suitable for mass *** the experimental stability test,an average quantum bit error rate of 0.59%was achieved through continuous operation for 10 h with-out any polarization ***,the chip enabled the automatic compensation of the fiber polarization drift when utiliz-ing the developed feedback algorithm,which was emulated by a ran-dom fiber polarization ***,a finite-key secret rate of 240 bps over a fiber spool of 100 km was achieved in the case of the QKD *** study marks an important step to-ward the integrated,practical,and large-scale deployment of QKD systems.

关键词： Quantum key distribution Silicon photonics Chip Polarization-encoding Polarization compensation

黄原胶生物聚合物改良膨胀土裂隙演化规律研究

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岩土工程学报 2025年第1期47卷 106-114页

作者：欧阳淼张红日邓人睿王桂尧肖杰赵亚长沙理工大学土木工程学院湖南长沙410114 广西交科集团有限公司广西南宁530007 上海交通大学土木工程系上海200240 长沙理工大学交通运输工程学院湖南长沙410114

采用既可抑制膨胀土裂隙扩展,又不影响坡面植被生长的黄原胶生物聚合物对膨胀土进行改良,是膨胀土边坡生态防护新思路。对黄原胶改良膨胀土开展室内干湿循环试验,利用数字图像处理技术(PCAS)对裂隙发育的整个过程进行定量分析,探究了黄... 详细信息

采用既可抑制膨胀土裂隙扩展,又不影响坡面植被生长的黄原胶生物聚合物对膨胀土进行改良,是膨胀土边坡生态防护新思路。对黄原胶改良膨胀土开展室内干湿循环试验,利用数字图像处理技术(PCAS)对裂隙发育的整个过程进行定量分析,探究了黄原胶掺量对膨胀土裂隙形态特征指标的影响规律,并通过扫描电镜(SEM)、X射线衍射(XRD)试验分析了改良前后膨胀土的微观结构与矿物成分的变化,结合膨胀率试验结果探讨了黄原胶对膨胀土的改良机理。研究结果表明,黄原胶的掺入可以有效提高膨胀土的保水性和抗裂性,试样的平均失水速率和裂隙率均随着掺量的增加呈减小趋势;黄原胶能够降低干湿循环效应对膨胀土的影响,将裂隙宽度控制在较小范围内,增湿过程中易闭合;黄原胶主要通过两个方面抑制膨胀土开裂,一方面通过成键和胶结作用与土颗粒形成“桥联”结构,整体增强土体的抗拉强度;另一方面通过填充和成膜作用阻隔水分与土颗粒接触,减小黏土矿物的水化膜厚度。

关键词：道路工程黄原胶生物聚合物干湿循环裂隙微观结构

Progress in understanding hormonal regulation during the postembryonic development of Helicoverpa armigera

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Journal of Integrative Agriculture 2020年第6期19卷 1417-1428页

作者： zhao xiao-fan Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology School of Life SciencesShandong UniversityQingdao 266237P.R.China

Lepidoptera,with 0.16 million species,is the second largest order of *** order includes silk worms,butterflies,and many agricultural *** cotton bollworm,Helicoverpa armigera(Hubner)is one of the pests in Lepidoptera that seriously harms cotton plant and other crops in China and other *** pest develops resistance to chemical insecticides *** thuringiensis(Bt)transgenic cotton plants are developed to control *** population in the ***,duri ng the past years,the rapid evoluti on of Bt toxi n resista nee is observed in *** in tran sge nic cott on *** approaches for the development of new envir on mentally friendly insecticides to control *** have become necessary,and the molecular mechanisms underlying the development and physiological processes of this species need to be further *** progress in the study of *** development and physiology has been achieved in the last *** mini-review summarizes the main fin dings on the molecular mechanisms of horm onal regulation of the development of *** to present new target genes for developing new approaches to control the pest.

关键词： Helicoverpa armigera Lepidoptera hormonal regulation development pest control

A Multiplicity Result of Positive Solutions for a Class of Multi-parameter Ordinary Differential Systems

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Acta Mathematicae Applicatae Sinica 2012年第4期28卷 653-662页

作者： xi-you CHENG xiao-lin YAN School of Mathematics and Statistics Lanzhou University School of Science Tianjin Polytechnic University

In this paper, we establish a result of Leray-Schauder degree on the order interval which is induced by a pair of strict lower and upper solutions for a system of second-order ordinary differential equations. As applications, we prove the global existence of positive solutions for a multi-parameter system of second-order ordinary differential equations with respect to parameters. The discussion is based on the result of Leray- Schauder degree on the order interval and the fixed point index theory in cones.

关键词： positive solution ordinary differential system fixed point index

Learning curves of resection and reconstruction procedures in robotic-assisted pancreatoduodenectomy by a single surgeon:a retrospective cohort study of 160 consecutive cases

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Gastroenterology Report 2023年第1期11卷 424-432页

作者： xi-Tai Huang xi-Yu Wang Jin-zhao xie Jian-Peng Cai Wei Chen Liu-Hua Chen xiao-Yu Yin Department of Pancreato-Biliary Surgery The First Affiliated HospitalSun Yat-sen UniversityGuangzhouGuangdongP.R.China

Background:Robotic-assisted pancreatoduodenectomy(RPD)has been routinely performed in a few of centers *** study aimed to evaluate the perioperative outcomes and the learning curves of resection and reconstruction procedures in RPD by one single ***:Consecutive patients undergoing RPD by a single surgeon at the First Affiliated Hospital of Sun Yat-sen University(Guangzhou,China)between July 2016 and October 2022 were *** perioperative outcomes and learning curves were retrospectively analysed by using cumulative sum(CUSUM)***:One-hundred and sixty patients were *** to the CUSUM curve,the times of resection and reconstruction procedures were shortened significantly after 30 cases(median,284 vs 195 min;P<0.001)and 45 cases(median,138 vs 120 min;P<0.001),*** estimated intraoperative blood loss(median,100 vs 50 mL;P<0.001)and the incidence of clinically relevant post-operative pancreatic fistula(29.2%vs 12.5%;P=0.035)decreased significantly after 20 and 120 cases,*** were no significant differences in the total number of lymph nodes examined,post-operative major complications,or post-operative length-of-stay between the two ***:Optimization of the resection procedure and the acquisition of visual feedback facilitated the performance of *** was a safe and feasible procedure in the selected patients.

关键词： robotic-assisted surgery pancreatoduodenectomy learning curve outcomes

Novel Crystallization Behaviors of Zr-Based Metallic Glass Under Thermo-Mechanical Coupled Fatigue Loading Condition

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Acta Metallurgica Sinica(English Letters) 2019年第7期32卷 797-802页

作者： Zhi-Chao Ma xiao-xi Ma Hong-Wei zhao Fu Zhang Li-Ming Zhou Lu-Quan Ren School of Mechanical and Aerospace Engineering Jilin University Changchun 130025 China Key Laboratory of Bionic Engineering Ministry of Education Jilin University Changchun 130025. China

Novel crystallization behaviors of Zr55Cu30Al10Ni5 bulk metallic glass are investigated. On the one hand, mixed oxides, including CuO, CuAlO2, CuA12O4 and ZrO2, show sequential oxidation process determined by coupling effects of specific cyclic load and temperature. On the other hand, at a temperature (100℃) by far lower than Tg of 412 ℃, under cyclic loading condition, non-oxidized binary alloy CuZr2 is precipitated;the thermo-mechanical coupled effects of temperature below Tg, and fatigue accumulation on the non-oxidized crystallization behaviors are revealed. Meanwhile, at a constant temperature of 400 ℃, by comparing among the XRD patterns, respectively, obtained from tensile, creep and fatigue fractures, the dominating effect of cyclic load on the generation of non-oxidized CuZr2 is verified. Furthermore, the crystallization behavior of amorphous phases under cyclic loading condition is observed through TEM micrograph and diffraction pattern at 100℃.

关键词： Bulk metallic glass Fatigue Thermo-mechanical coupling Crystallization