Modelling and analysis of metal flowing behaviors in constraining ring rolling of tapered ring with thin wall and three high ribs

Tapered ring with thin wall and three high ribs(TRTWTHR),showing complicated geometry(wall thickness is less than 4 mm and rib height exceeds 20 mm),is extensively utilized to fabricate the critical structural parts of aerospace equipment such as spacecraft cabin,rocket body and fuel tank because of light weight and high carrying capacity.How to fabricate TRTWTHR with high performance is a critical problem that aerospace area needs to solve.In this work,constraining ring rolling(CRR)technique is first adopted to form TRTWTHR.However.unreasonable metal streamlines(UMS)and uncoordinated growth of three ribs easily occur in CRR of TRTWTHR,which makes the forming quality of TRTWTHR difficult to be controlled.Faced with this difficulty,an analytical model that can predict UMS and the height of three ribs in CRR of TRTWTHR is established so as to guide the process design of CRR.Subsequently,the reliability of the established analytical model and the feasibility of CRR of TRTWTHR are confirmed by FE simulation and experiment.Then,using the established analytical model,the window of UMS occurring relevant to the tapered angle of TRTWTHR and the location of the rib of middle end is developed.Finally,three uncoordinated growth modes among three ribs are found when the width of three ribs is identical and UMS do not occur,and the mechanisms of three uncoordinated growth modes are revealed.

Three-dimensional simulation method of multipactor in microwave components for high-power space application

Based on the particle-in-cell technology and the secondary electron emission theory, a three-dimensional simulation method for multipactor is presented in this paper. By combining the finite difference time domain method and the panicle tracing method, such an algorithm is self-consistent and accurate since the interaction between electromagnetic fields and particles is properly modeled. In the time domain aspect, the generation of multipactor can be easily visualized, which makes it possible to gain a deeper insight into the physical mechanism of this effect. In addition to the classic secondary electron emission model, the measured practical secondary electron yield is used, which increases the accuracy of the algorithm. In order to validate the method, the impedance transformer and ridge waveguide filter are studied. By analyzing the evolution of the secondaries obtained by our method, multipactor thresholds of these components are estimated, which show good agreement with the experimental results. Furthermore, the most sensitive positions where multipactor occurs are determined from the phase focusing phenomenon, which is very meaningful for multipactor analysis and design.

High-capacity three-party quantum secret sharing with superdense coding

This paper presents a scheme for high-capacity three-party quantum secret sharing with quantum superdense coding, following some ideas in the work by Liuet al （2002 Phys. Rev. A 65 022304） and the quantum secret sharing scheme by Deng et al （2008 Phys. Lett. A 372 1957）. Instead of using two sets of nonorthogonal states, the boss Alice needs only to prepare a sequence of Einstei^Podolsky-l^osen pairs in d-dimension. The two agents Bob and Charlie encode their information with dense coding unitary operations, and security is checked by inserting decoy photons. The scheme has a high capacity and intrinsic efficiency as each pair can carry 21bd bits of information, and almost all the pairs can be used for carrying useful information.

Oxidation behavior of three-phase Cu-25Ni-30Cr alloy at 700-800℃ under high oxygen pressures

The thermogravimetric analysis of a ternary Cu-25Ni-30Cr alloy prepared by conventional casting was performed in 0.1MPa pure O2 at 700-800℃. The results show that the alloy is composed of three phases, where the phase with the largest copper and lowest chromium content forms the matrix, while the other two, much richer in chromium, form a dispersion of isolated particles. At variance with another three-phase Cu-20Ni-20Cr alloy, which forms complex scales containing the oxides of the various components and double oxides plus an irregular region composed of alloy and oxides, the present alloy can form a very irregular but continuous chromia layer at the base of the mixed internal region, producing a gradual decrease of the oxidation rate down to very low values. A larger chromium content needed to form chromia layer for a ternary three-phase alloy is attributed to the limitations to the diffusion of the alloy components in the metal substrate imposed by their multiphase nature.

Progress and Development Direction of “Three-High” Oil and Gas Well Testing Technology

By reviewing the development of “three-high” oil and gas well testing technology of Sinopec in recent years, this paper systematically summarizes the application of “three-high” oil and gas well testing technology of Sinopec in engineering optimization design technology, and high temperature and high pressure testing technology, high pressure and high temperature transformation completion integration technology. Major progress has been made in seven aspects: plug removal and re-production technology of production wells in high acid gas fields;wellbore preparation technology of ultra-deep, high-pressure, and high-temperature oil and gas wells;surface metering technology;and supporting tool development technology. This paper comprehensively analyzes the challenges faced by the “three-high” oil and gas well production testing technology in four aspects: downhole tools, production testing technology, safe production testing, and the development of low-cost production test tools. Four development directions are put forward: 1) Improve ultra-deep oil and gas testing technology and strengthen integrated geological engineering research. 2) Deepen oil and gas well integrity evaluation technology to ensure the life cycle of oil and gas wells. 3) Carry out high-end, customized, and intelligent research on oil test tools to promote the low-cost and efficient development of ultra deep reservoirs. 4) Promote the fully automatic control of the surface metering process to realize the safe development of “three-high” reservoirs.

Microfluidic three-dimensional cell culture of stem cells for high-throughput analysis

Although the recent advances in stem cell engineering have gained a great deal of attention due to their high potential in clinical research,the applicability of stem cells for preclinical screening in the drug discovery process is still challenging due to difficulties in controlling the stem cell microenvironment and the limited availability of high-throughput systems.Recently,researchers have been actively developing and evaluating three-dimensional(3D)cell culture-based platforms using microfluidic technologies,such as organ-on-a-chip and organoid-on-a-chip platforms,and they have achieved promising breakthroughs in stem cell engineering.In this review,we start with a comprehensive discussion on the importance of microfluidic 3D cell culture techniques in stem cell research and their technical strategies in the field of drug discovery.In a subsequent section,we discuss microfluidic 3D cell culture techniques for high-throughput analysis for use in stem cell research.In addition,some potential and practical applications of organ-on-a-chip or organoid-on-a-chip platforms using stem cells as drug screening and disease models are highlighted.

Electromagnetically induced transparency of single Λ-type three-level atoms in a high-finesse optical cavity

We study the features of electromagnetically induced transparency（EIT） in a single Λ-type three-level atom placed in a high-finesse cavity under the action of a coupling laser and a probe laser.Our calculations show that three transparency windows appear when the pump strength is large enough.This can be explained by the residual pump in the cavity mostly resulting in energy splitting.The level ｜3 is split into four slightly different energy levels,and interference takes place between the excitation pathways.Furthermore,it is also shown that the frequencies of the EIT windows can be tuned by changing the coupling field detuning 2,and that the reflection profile is very sensitive to the cavity field detuning △c.

中国新能源产业高质量发展:进展、挑战及对策

大力发展新能源是改善我国能源结构,保障国家能源安全,实现碳达峰碳中和美好愿景的必然选择。一方面,新能源的大规模开发利用,可以有效减少对传统化石能源和进口能源的依赖,降低环境污染和温室气体排放,为经济社会发展提供绿色低碳且可持续的能源支撑。另一方面,新能源产业属于我国新质生产力,代表着科技革命和产业变革的新方向、新趋势。新能源技术的发展和产业链的构建,可以有力地带动装备制造、科技研发、配套服务等相关产业的发展,促进技术创新和产业升级,培育新的经济增长点,对于我国加快产业结构优化升级、增强经济综合竞争力具有重要意义。

Mechanical effects of light on the ■-type three-level atom in a high-finesse optical cavity

A theoretical study is carried out for the modification and implication of the effect on the type three level atom in a high-finesse optical cavity driven by light field including spontaneous emission and the cavity decay. Analytic expressions for the dipole force, the friction force, the optical potentials and the friction coefficient are obtained. Then the numerical and graphical methods are used to investigate the friction coefficient with the controlling parameters. It is shown that the friction coefficient is strongly dependent on the controlling parameters. The cooling rate can increase by one order of magnitude more than that of a two-level atomic system. The reason can be given using the dressed states and the Sisyphus cooling mechanism, which would stimulate further experimental investigations.

Sequential transcatheter arterial chemoembolization,three-dimensional conformal radiotherapy,and high-intensity focused ultrasound treatment for unresectable hepatocellular carcinoma patients

The purpose of this study was to evaluate the outcome of patients with unresectable hepatocellular carcinoma（HCC） treated by sequential therapy of transcatheter arterial chemoembolization（TACE）,three-dimensional conformal radiotherapy（3-DCRT） and high-intensity focused ultrasound（HIFU）.From October,2005 to September,2010,120 patients with unresectable HCC received the sequential treatments of several courses of TACE followed in 2-4 weeks by 3-DCRT and then a single session of HIFU with a curative intent.The median tumor irradiation dose was 40 Gy.Tumor response,toxicity and overall survival rate were analyzed.Clinicopathologic factors affecting the primary technique effectiveness and overall survival rates were investigated by univariate analysis or multivariate analysis.All 120 HCC patients were followed up by the last follow-up time.Among these patients,hepatic toxicities due to treatment were notable in 9 cases.Gastrointestinal bleeding after the overall treatment occurred in 2 cases,leukopenia of grade III was detected in 1 case,radiation-induced liver disease（RILD） was observed in 2 patients,and first-and second-degree skin burn around the HIFU treatment zone were observed in 2 patients and 1 patient,respectively.Among 120 patients,23,83 and 14 cases achieved partial response,stable disease and progressive disease,respectively.The overall survival rates at 1 year,3 years and 5 years were 70%,35% and 15%,respectively,with a median survival time of 26 months.Both Child-Pugh liver function grading and radiation dose were determined to be independent predictors for overall survival revealed by the multivariate analysis.It is concluded that the sequential therapy of TACE,3-DCRT and HIFU is a promising therapeutic regimen for unresectable HCC.

“三高四新”背景下高职物流人才培养模式创新研究

“三高四新”战略背景下,企业对物流人才的需求逐渐转向多能力、跨学科、复合型。文章提出了“三高四新”战略背景下的高职物流“知行创”三融入人才培养模式,指出了从培养目标、课程体系、评价体系等方面进行高职物流人才培养模式的改革,旨在培养出懂设备使用、懂流程规划、懂投资回报和懂现场管理的物流人才,为高职物流专业的人才培养方案制定提出了有益建议。

“三高三难”背景下职业院校虚拟仿真实训改革初探

高职教育的高质量发展,需要进行实训教学改革来解决当前实训存在的“高投入高难度高风险、难实施难观摩难再现”问题。虚拟仿真实训改革应结合教学实际、企业生产、区域发展,以现有实训基地建设为基础,以多种信息技术为手段,聚焦行业需求,搭建企业和学生双向需求通道,科学构建实训课程评价体系,整合校企课程资源,构建共建共享共用机制,实现大范围资源共享,最终实现高技能人才培养的信息化、智能化和现代化的目标。

Three-Dimensional Analysis of Melanosomes Isolated from B16 Melanoma Cells by Using Ultra High Voltage Electron Microscopy

Melanosomes, isolated by centrifugal separation from culture broth of B16 melanoma cells derived from mouse, were observed by scanning electron microscopy (SEM), and by transmission electron microscopy (TEM). Some interesting structural features were found inside and outside of the melanosomes. By SEM observation, the melanosomes were ellipsoid shape, their surface was not smooth and was covered with rough substructure, 10 to 20 nm particles. By TEM, uneven structure and micro particles were observed in the melanosomes. Furthermore, three-dimensional analysis was tried by using the ultra-high voltage electron microscopy(UHVEM). Micrographs of the melanosomes were taken at various tilted angles by UHVEM, after preparing 500 nm thickness specimens stained with lead citrate. From the micrographs collected, the three-dimensional structures were reconstructed by using i-mode software. Melanin stained by lead and non stained parts was clearly observed in the reconstructed structure. Non stained parts were round, regular size, and distributed widely in the melanosomes.

Magnetic levitation performance of high-temperature superconductor over three magnetic hills of permanent magnet guideway with iron shims of different thicknesses

Superconducting magnetic levitation performance, including levitation force and guidance force, is important for the application of high-temperature super- conducting maglev. Both of them are not only affected by different arrays of superconductors and magnets, but also by the thickness of the iron shim between permanent magnets. In order to obtain the best levitation performance, the magnetic field distribution, levitation force, and guidance force of a new type of three magnetic hills of permanent magnet guideway with iron shim of different thicknesses （4, 6, and 8 mm） are discussed in this paper. Simulation analysis and experiment results show that the guideway with iron shim of 8 mm thickness possesses the strongest magnetic field and levitation performance when the suspension gap is larger than 10 mm. However, with the decreasing of suspension gap, the guideway with iron shim of 4 mm thickness possesses the best levitation performance. The phenomena can be attributed to the density distribution of flux and magnetization of iron shim.

桩端岩溶三维超声成像方法及应用研究

研究目的:岩溶地区大直径桩基础受桩端岩溶的威胁大,探查不清或处理不当时可能会出现桩基承载力不足等严重工程质量问题,现有探测方法难以在桩底复杂泥水环境下实现桩端三维精细化探测。本文基于超声相控阵全聚焦成像原理,提出一种全新的桩端岩溶三维探测方法,以实现对桩端一定范围内地质结构进行三维高精度成像。研究结论:(1)本方法和装备在桩底采集超声数据并成像,可对桩端一定深度和冲切角范围内岩溶三维高精度成像;(2)足尺模型试验表明本装备可探测桩端10 m以内溶洞且探测精度优于0.1 m;(3)工程实践表明本装备可有效查明桩端岩溶、破碎裂隙,探测结果准确可靠;(4)本装备能适应桩底各种恶劣的环境,探测过程简单高效,时效性强,对保障岩溶区桩基施工安全与质量控制具有重要的意义。

“三高四新”战略下研究生实践创新能力发展研究

在贯彻落实“三高四新”战略定位背景下,湖南省研究生教育需要培养更多的创新型人才,以促进湖南省社会经济快速发展和提升中国的国际竞争力。基于此,分析了“三高四新”战略背景下通过产学研结合推动高校研究生实践创新能力发展的意义,探讨了现阶段造成高校研究生实践创新能力不足的因素,提出了以构建产学研结合培养高校研究生实践创新能力的具体策略。研究表明,产学研结合下的研究生实践创新能力培养是加快技术进步、保持教育活力可持续发展的内生和外在动力,亦是推动落实“三高四新”战略定位的重要举措。

现代物流管理专业服务湖南省“三高四新”战略路径研究

近年来,湖南的物流行业实现了质的飞跃,这对推动“三高四新”战略的实施起到了关键作用,本文追溯了湖南省在现代物流管理领域的成长轨迹,探讨了其目前面临的挑战,并分析了现代物流管理对于国家关键先进制造业、科技革新和改革开放等方面的重要性。针对湖南地区特色,探索了现代物流管理专业服务“三高四新”战略的路径,包括提高人才培养水平、激励产业创新发展,以及推动区域经济协同发展等。最后,以湖南工程职业技术学院为例分析了该校现代物流管理专业在学生培养和校企合作方面所取得的显著成效。

基于深度学习的高分辨率三维激光雷达成像目标检测方法

高分辨率三维激光雷达成像目标检测中受到双目视觉耦合干扰导致检测精度不高,提出基于深度学习的高分辨率三维激光雷达成像目标检测方法。采用视觉传感器与惯性传感器实现对高分辨率三维激光雷达图像采集,通过激光点云特征提取和动态场景图像融合的方法实现对高分辨率的三维激光雷达合成,采用补偿滤波方法实现对三维激光雷达成像目标检测过程中的点云畸变矫正处理,通过局部滑动窗口的图特征匹配和深度学习模型,建立激光雷达成像目标检测的深度特征匹配模型,根据特征匹配结果和激光雷达帧图匹配结果,实现对高分辨率三维激光雷达成像目标检测。仿真测试结果表明,采用该方法进行目标检测的激光雷达成像在噪声干扰下,峰值信噪比最低为41 dB,检测精度达到0.96。

成人高血压合并2型糖尿病和血脂异常基层防治中国专家共识(2024年版)

高血压、2型糖尿病、血脂异常被统称为“三高”,常同时存在于同一个体中,显著增加了患者的住院和死亡风险,以及相关疾病负担。因此,有必要对三者进行共同风险管理和规范治疗。基层医疗卫生机构是慢性病防治的“主战场”,现有临床证据对“三高”人群的基层预防、治疗及管理具有重要启示,但目前国内外尚无适用于基层的“三高”共管规范、共识和指南。北京高血压防治协会等4家学/协会组织基层医务人员,并邀请心血管、内分泌、药学及公共卫生等诸多领域专家/学者共同参与,广泛征询基层医务人员临床实践需求,在整合与评价“三高”基层防治相关证据的基础上,经过多轮讨论、修订与投票表决,形成了包含21条推荐意见的“三高”基层防治专家共识。本共识的推荐意见旨在提高基层医务人员的“三高”防治意识和能力,为基层医疗卫生机构开展“三高”防治提供科学的策略支持,为实施具有基层特色的“三高”共管奠定坚实基础。

高质量发展下区域绿色物流效率评价研究

区域绿色物流是推进物流业绿色发展的重要元素。基于DFSO提出高质量发展视域下绿色物流框架并构建效率测度指标体系,运用改进三阶段DEA模型对中国30个省(市)进行实证研究,分析各因素对绿色物流效率的影响。结果表明高质量发展视域下省域绿色物流整体效率不高,地区差异明显,纯技术效率是制约其发展的主要因素;高质量发展各方面均对绿色物流效率有不同程度的影响,但二者间的协调仍处初级阶段。基于此,提出高质量发展视域下区域绿色物流效率提升的对策建议。研究能够为相关部门衡量高质量发展时期物流业绿色发展成效、精准施策提供参考。