检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

沟槽机筒单螺杆挤出机耦合双槽熔融理论研究

中国塑料 2015年第10期29卷 88-93页

作者：金晓明贾明印薛平李珊珊王金阵北京化工大学塑料机械及塑料工程研究所北京100029 北京化工大学机电工程学院北京100029

利用自制的液压剖分式沟槽机筒单螺杆挤出机实验平台,研究了沟槽机简单螺杆挤出机的熔融长度和螺杆转速的关系,实验验证了单螺杆挤出机固体输送段和熔融段机筒均开设沟槽的耦合双槽熔融理论。结果表明,与传统光滑机筒单螺杆挤出机和IKV... 详细信息

利用自制的液压剖分式沟槽机筒单螺杆挤出机实验平台,研究了沟槽机简单螺杆挤出机的熔融长度和螺杆转速的关系,实验验证了单螺杆挤出机固体输送段和熔融段机筒均开设沟槽的耦合双槽熔融理论。结果表明,与传统光滑机筒单螺杆挤出机和IKV单螺杆挤出机相比,在熔融段机筒开设沟槽的单螺杆挤出机的熔融长度较短且熔融过程比较稳定,熔融效率得到较大提高。

关键词：沟槽机筒熔融长度剖分式机筒单螺杆挤出机

在线全文

学校读者我要写书评

暂无评论

沟槽机筒挤出机塑化特性的超声波表征

工程塑料应用 2018年第7期46卷 78-82页

作者：杨茜贾明印薛平熊文楠曹宏星北京化工大学机电工程学院北京100029

分析了制品超声波特征回波幅值和沟槽机筒挤出机塑化特性的关系,构建了基于超声波特征幅值衰减的评价方法,通过实验研究,探明了机筒结构和螺杆结构对沟槽机筒挤出机塑化特性的影响,并结合可视化实验研究对结果进行了验证。结果表明,在... 详细信息

分析了制品超声波特征回波幅值和沟槽机筒挤出机塑化特性的关系,构建了基于超声波特征幅值衰减的评价方法,通过实验研究,探明了机筒结构和螺杆结构对沟槽机筒挤出机塑化特性的影响,并结合可视化实验研究对结果进行了验证。结果表明,在相同的螺杆结构条件下,压缩段沟槽机筒挤压系统加工的制品对超声波的衰减作用最小,即该挤压系统有较好的塑化效果;在相同的机筒结构条件下,随着螺杆压缩比增大,物料的塑化程度不断提高,且实验结果与可视化研究一致。

关键词：沟槽机筒挤出机塑化特性结构超声波表征

在线全文

学校读者我要写书评

暂无评论

聚乙烯醇改性地质聚合物复合材料的性能研究

矿产综合利用 2018年第3期 125-128,51页

作者：阚鑫禹薛平贾明印章亚北京化工大学新材料及装备研究室北京100029 中澳环球快建房科技有限公司天津301712

由于矿粉/粉煤灰基地质聚合物的韧性较差,本文选用聚乙烯醇纤维和水溶性粉末对其进行增韧改性研究。研究表明:聚乙烯醇水溶性粉末的掺量为0.5%时,抗压和抗折强度分别提高9.6%和25%,可以起到增韧作用,但掺量继续增加会导致力学性能大幅下... 详细信息

由于矿粉/粉煤灰基地质聚合物的韧性较差,本文选用聚乙烯醇纤维和水溶性粉末对其进行增韧改性研究。研究表明:聚乙烯醇水溶性粉末的掺量为0.5%时,抗压和抗折强度分别提高9.6%和25%,可以起到增韧作用,但掺量继续增加会导致力学性能大幅下降;随着聚乙烯醇纤维掺量的不断提高,抗压强度持续降低,抗折强度不断提高,压折比不断降低,当掺量为3%时,抗折强度提高35%,压折比降低35%。结合XRD测试和SEM-EDS分析,研究聚乙烯醇对地质聚合物微观结构的影响,结果表明聚乙烯醇纤维和水溶性粉末具有不同的增韧机理。

关键词：地质聚合物聚乙烯醇压折比增韧

口模拉伸过程PP/CaCO_(3)复合材料结构演变及机理

在线全文

学校读者我要写书评

暂无评论

中国塑料 2022年第10期36卷 1-6页

作者：禹世康陈轲薛平贾明印蔡建臣北京化工大学塑料机械及塑料工程研究所北京100029 衢州学院机电工程学院浙江衢州324000

利用口模拉伸法制备了轻质、高强、高模的聚丙烯(PP)/碳酸钙(CaCO_(3))复合材料,分析了口模拉伸对材料微观结构、晶体结构、热性能和密度的影响,揭示了口模拉伸过程中材料结构演变及其机理。结果表明,随着拉伸过程的进行,材料内的原始... 详细信息

利用口模拉伸法制备了轻质、高强、高模的聚丙烯(PP)/碳酸钙(CaCO_(3))复合材料,分析了口模拉伸对材料微观结构、晶体结构、热性能和密度的影响,揭示了口模拉伸过程中材料结构演变及其机理。结果表明,随着拉伸过程的进行,材料内的原始球晶向微纤状晶体转变,同时发生晶粒细化现象,结晶度增大表明存在拉伸诱导结晶现象。微孔尺寸的显著增大及材料密度的显著降低主要发生在材料离开收敛流道壁面后的自由拉伸过程中。

关键词：口模拉伸聚丙烯复合材料取向拉伸诱导结晶微孔

Design method and experimental study of a cathode tool with an extremely high leveling ratio for electrochemical machining of blisk

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第4期37卷 593-608页

作者： Moqi SHEN jia LIU Jingtao WANG Di ZHU College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

To obtain final parts with the desired dimensional accuracy and repeatability via electrochemical machining(ECM), the machining process must enter an ECM balanced state. However,for the ECM processing of blisk, a key component of aerospace engines, the surface of the blade blank often has an uneven allowance distribution due to the narrow passage of the cascade. It is difficult to remedy this issue in subsequent processing steps, which is necessary to ensure the dimensional accuracy and repeatability of the final blade profile. To solve this problem, electrolytic machining must be preceded by electrolytic shaping, which requires cathode tools with large leveling ratios to quickly homogenize the blank surface of the blade. In this study, to obtain a cathode tool with an extremely high leveling ratio, a design method based on the variation in the electrode gap in the non-equilibrium electrolytic state is proposed, and a dissolution model based on the nonequilibrium state is established. In this design method, the allowance on the blank to be machined is first divided into many discrete allowances with the normal direction. The initial machining clearance, feed rate, and total machining time are then calculated using classical ECM equilibrium state theory based on the maximum allowance. Meanwhile, the point coordinates of the cathode tool at maximum allowance can be determined. The non-equilibrium model can then be used to calculate the relative coordinate positions corresponding to the remaining discrete allowances. Finally, the entire cathode tool profile is designed. Simulations, fundamental experiments, and blisk unit workpiece experiments were carried out to validate the design approach. In the simulated processing of the plane workpiece, the leveling ratio of the cathode tool designed by the proposed method(0.77)was 83% higher than that of the cathode tool designed using the traditional method. The simulation results were confirmed by processing experiments. In t

关键词： Electrochemical machining(ECM) Non-equilibrium machining Large leveling ratios Cathode design Finite element simulation Blisk

Ballistic performances of the hourglass lattice sandwich structures under high-velocity fragments

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第1期31卷 312-325页

作者： He-xiang Wu jia Qu Lin-zhi Wu Key Laboratory of Advanced Ship Materials and Mechanics College of Aerospace and Civil EngineeringHarbin Engineering UniversityHarbin150001China School of Civil Engineering Northeast Forestry UniversityHarbin150040China

In this paper,the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of *** is paid to elucidating the influences of rod cross-section dimensions,structure height,structure layer,and rod inclination angle on the deformation mode,ballistic performances,and ability to change the ballistic direction of *** results show that the ballistic performances of hourglass lattice sandwich structures are mainly affected by their structural *** this respect,structural parameters optimization of the hourglass lattice sandwich structures enable one to effectively improve their ballistic limit velocity and,consequently,ballistic performances.

关键词： Hourglass lattice sandwich structures Ballistic performances high-velocity Finite element analysis

Nab-paclitaxel plus capecitabine as first-line treatment for advanced biliary tract cancers:An open-label,non-randomized,phase II clinical trial

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2024年第30期30卷 3564-3573页

作者： Ling-Xiao Xu jia-jia Yuan Ran Xue Jun Zhou Department of Gastrointestinal Oncology Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education/Beijing)Peking University Cancer Hospital and InstituteBeijing 100142China

BACKGROUND Biliary tract cancers(BTCs)are a heterogeneous group of tumors with high malignancy,poor prognosis,and limited treatment *** To explore the efficacy and safety of nab-paclitaxel plus capecitabine as first-line treatment for advanced and metastatic *** This open-label,non-randomized,double-center,phase II clinical trial recruited systemic therapy-naive patients with unresectable or metastatic BTCs between April 2019 and June 2022 at Beijing Cancer Hospital and the First Hospital of China Medical *** patients were administered nab-paclitaxel(150 mg/m^(2),day 1)and capecitabine(2000 mg/m^(2),twice daily,days 1-7)in 14-day cycles until experiencing intolerable toxicity or disease *** primary outcome was the objective response rate(ORR).The secondary outcomes included the disease control rate(DCR),overall survival(OS),progression-free survival(PFS),and *** A total of 44 patients successfully completed the trial,with a median age of 64.00 years(interquartile range,35.00-76.00),and 26(59.09%)were *** response assessment was impeded for one patient due to premature demise from tumor *** the remaining 43 patients undergoing at least one imaging assessment,the ORR was 23.26%[95%confidence interval(CI):11.80%-38.60%],and the DCR was 69.77%(95%CI:53.90%-82.80%).The median OS was 14.1 months(95%CI:8.3-19.9),and the median PFS was 4.4 months(95%CI:2.5-6.3).A total of 41 patients(93.18%)experienced at least one adverse event(AE),with 10 patients(22.73%)encountering grade≥3 AEs,and the most frequent AEs of any grade were alopecia(79.50%),leukopenia(54.55%),neutropenia(52.27%),and liver dysfunction(40.91%),and no treatment-related deaths were *** Nab-paclitaxel plus capecitabine may be an effective and safe first-line treatment strategy for patients with advanced or metastatic BTCs.

关键词： Nab-paclitaxel Capecitabine Biliary tract cancer Objective response rate Phase II clinical trial

Distributed collaborative complete coverage path planning based on hybrid strategy

维普期刊数据库评论

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 Engineering and Electronics 2024年第2期35卷 463-472页

作者： ZHANG jia DU Xin DONG Qichen XIN Bin School of Automation Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Autonomous Intelligent Unmanned Systems Beijing Institute of TechnologyBeijing 100081China

Collaborative coverage path planning(CCPP) refers to obtaining the shortest paths passing over all places except obstacles in a certain area or space. A multi-unmanned aerial vehicle(UAV) collaborative CCPP algorithm is proposed for the urban rescue search or military search in outdoor *** to flexible control of small UAVs, it can be considered that all UAVs fly at the same altitude, that is, they perform search tasks on a two-dimensional plane. Based on the agents’ motion characteristics and environmental information, a mathematical model of CCPP problem is established. The minimum time for UAVs to complete the CCPP is the objective function, and complete coverage constraint, no-fly constraint, collision avoidance constraint, and communication constraint are considered. Four motion strategies and two communication strategies are designed. Then a distributed CCPP algorithm is designed based on hybrid strategies. Simulation results compared with patternbased genetic algorithm(PBGA) and random search method show that the proposed method has stronger real-time performance and better scalability and can complete the complete CCPP task more efficiently and stably.

关键词： multi-agent cooperation unmanned aerial vehicles(UAV) distributed algorithm complete coverage path planning(CCPP)

拉伸温度对UHMW-PE/HDPE共混纤维结晶性能的影响

在线全文

学校读者我要写书评

暂无评论

塑料 2018年第3期47卷 76-79页

作者：王非刘丽超薛平贾明印王苏炜北京化工大学塑料机械及塑料工程研究所北京100029

通过熔融纺丝工艺成功制备了超高分子量聚乙烯(UHMW-PE)/高密度聚乙烯(HDPE)共混初生丝,并将初生丝在不同温度下进行高倍率热拉伸制得UHMW-PE/HDPE共混纤维。采用广角X射线衍射(WAXD)、差示扫描量热(DSC)、拉伸试验等方法探讨了不同热... 详细信息

通过熔融纺丝工艺成功制备了超高分子量聚乙烯(UHMW-PE)/高密度聚乙烯(HDPE)共混初生丝,并将初生丝在不同温度下进行高倍率热拉伸制得UHMW-PE/HDPE共混纤维。采用广角X射线衍射(WAXD)、差示扫描量热(DSC)、拉伸试验等方法探讨了不同热拉伸温度下获得的UHMW-PE/HDPE共混纤维的微观结构及力学性能。结果表明,在85℃下拉伸所得的纤维具有最高的结晶度、结晶取向度以及最细长的晶粒形状,纤维的力学性能也最优。太低的拉伸温度不利于纤维的分子链以及晶体结构沿轴向取向,太高的拉伸温度则不利于纤维的晶体结构在拉伸过程中进行重组,因此太低或太高的拉伸温度均不利于纤维力学性能的提升。

关键词：超高分子量聚乙烯高密度聚乙烯共混熔融纺丝晶体结构拉伸温度