检索结果-南通市图书馆

尺蠖型超磁致伸缩旋转驱动器驱动信号设计与试验

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

农业机械学报 2024年第4期55卷 452-458页

作者：周景涛何忠波刘国平陆军工程大学石家庄校区石家庄050003

为了解决传统的“信号发生器+功率放大器”产生的信号无法满足尺蠖型旋转驱动器多路、正方波波形需求的问题,设计了一种通过Cmos控制脉冲模块“通-断”时机的信号控制器,从而得到特定时序的3路正方波信号。通过这种方案得到的3路驱动信... 详细信息

为了解决传统的“信号发生器+功率放大器”产生的信号无法满足尺蠖型旋转驱动器多路、正方波波形需求的问题,设计了一种通过Cmos控制脉冲模块“通-断”时机的信号控制器,从而得到特定时序的3路正方波信号。通过这种方案得到的3路驱动信号为正方波电流信号,从而避免了超磁致伸缩材料的“倍频”现象的发生。通过设置信号周期、占空比和延迟等参数,能够输出设定时序的三路正方波驱动信号。根据电压定律,将正方波简化成阶跃波形,建立了驱动信号的电流模型,并进行了参数辨识。在工作频率范围内,电流解析式能准确地表示电流信号。搭建试验平台进行了试验测试,试验结果表明,在工作频率范围内,信号控制器输出的正方波波形优于“信号发生器+功率放大器”产生的方波信号,设定的3路信号能够驱动尺蠖型旋转驱动器产生步进旋转运动。通过优化驱动信号时序,将旋转驱动器最大工作频率由160 Hz提至210 Hz。

关键词：超磁致伸缩旋转驱动器正方波信号时序尺蠖型

酿酒酵母稳定整合位点鉴定及其在橘烯生物合成中的应用

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

生物工程学报 2024年第6期40卷 1924-1934页

作者：陈东莹朱晁谊陈和锋周靖涛李爽华南理工大学生物科学与工程学院广东广州510006

橘烯(valencene)是一种带有柑橘香气的高值倍半萜类化合物,被广泛应用于食品、化妆品等行业,以及工业合成圆柚酮。本研究在酿酒酵母基因组中鉴定到了16个位于基因间区(intergenic region,IGR)的基因组位点,利用CRISPR-Cas9技术,将Ypet... 详细信息

橘烯(valencene)是一种带有柑橘香气的高值倍半萜类化合物,被广泛应用于食品、化妆品等行业,以及工业合成圆柚酮。本研究在酿酒酵母基因组中鉴定到了16个位于基因间区(intergenic region,IGR)的基因组位点,利用CRISPR-Cas9技术,将Ypet表达盒整合到不同的基因组位点,整合成功率高达87.50%,不同插入位点之间的表达差异达1.91倍。研究显示,位置效应在基因表达中相对稳定,基本不受启动子和报告基因变更的影响。之后筛选高效表达的元件组合PTDH3-TPRC1,在优选的整合位点迭代整合来自阿拉斯加黄扁柏(Callitropsis nootkatensis)橘烯合成酶(VSm),橘烯产量提升至254.67 mg/L。过表达多个拷贝的关键基因t HMG1-ERG20,橘烯的产量提高了93.49%。所得工程菌株L-13在3 L发酵罐中进行2阶段补料分批发酵能够生产橘烯9 530.18 mg/L,相较出发菌株提高了近100倍,展现了筛选出的基因组位点在橘烯生产优化过程中的潜力。

关键词：酿酒酵母位点效应 CRISPR-Cas9 橘烯生物合成

全民健康覆盖议程的全球发展历程、现状及挑战

在线全文

学校读者我要写书评

暂无评论

中华流行病学杂志 2024年第8期45卷 1171-1176页

作者：周景涛宁佩珊李黎饶蓁蓁胡国清中南大学湘雅公共卫生学院流行病与卫生统计学系长沙410006

全民健康覆盖议程有助于促进居民健康与社会公平,是WHO与各国政府的优先事项。本文就全民健康覆盖议程的基本概念、发展历程、涵盖内容、评价指标、全球进展以及所面临的挑战进行梳理。全民健康覆盖议程在经过半个多世纪的发展后,全球... 详细信息

全民健康覆盖议程有助于促进居民健康与社会公平,是WHO与各国政府的优先事项。本文就全民健康覆盖议程的基本概念、发展历程、涵盖内容、评价指标、全球进展以及所面临的挑战进行梳理。全民健康覆盖议程在经过半个多世纪的发展后,全球对其定义与内容已形成共识,即认为应从服务人口覆盖比例、医疗卫生服务与经济保护力度3个方面来定义全民健康覆盖;全民健康覆盖议程的实施原则是在资源受限的情况下优先为全民提供健康收益与社会价值较高的医疗卫生服务项目,但WHO与其他国际组织所提出的卫生服务推荐清单与评价框架更倾向于低收入国家,忽略了伤害与精神健康等服务内容,并不适用于所有国家;全民健康覆盖议程各维度间发展不均衡,低收入国家发展严重落后,非传染性疾病与伤害等防控工作进度滞后,低收入群体、弱势群体在服务获取与经济保护方面均处于劣势。建议全球建立一套用于确定高优先级医疗卫生服务的标准方法和流程,各国根据自身需求与能力逐渐扩展卫生服务内容与人口覆盖范围;提高医疗系统资源投入与国际协作,以推动低收入国家卫生系统建设与技术进步;建设高质量的初级卫生服务系统,加强对弱势群体的关注与保护。

关键词：全民健康覆盖可持续发展目标健康福利包

Optimum Weight Design of Functionally Graded Material Gears

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2015年第6期28卷 1186-1193页

作者： JING Shikai ZHANG He zhou jingtao SONG Guohua School of Mechanical Engineering Beijing Institute of Technology Key Lab of Contemporary Design and Integrated Manufacturing Technology Ministry of EducationNorthwestern Polytechnical University

Traditional gear weight optimization methods consider gear tooth number, module, face width or other dimension parameters of gear as design variables. However, due to the complicated form and geometric features peculiar to the gear, there will be large amounts of design parameters in gear design, and the influences of gear parameters changing on gear trains, transmission system and the whole equipment have to be taken into account, which increases the complexity of optimization problem. This paper puts forward to apply functionally graded materials（FGMs） to gears and then conduct the optimization. According to the force situation of gears, the material distribution form of FGM gears is determined. Then based on the performance parameters analysis of FGMs and the practical working demands for gears, a multi-objective optimization model is formed. Finally by using the goal driven optimization（GDO） method, the optimal material distribution is achieved, which makes gear weight and the maximum deformation be minimum and the maximum bending stress do not exceed the allowable stress. As an example, the applying of FGM to automotive transmission gear is conducted to illustrate the optimization design process and the result shows that under the condition of keeping the normal working performance of gear, the method achieves in greatly reducing the gear weight. This research proposes a FGM gears design method that is able to largely reduce the weight of gears by optimizing the microscopic material parameters instead of changing the macroscopic dimension parameters of gears, which reduces the complexity of gear weight optimization problem.

关键词： gears optimum weight design functionally graded materials material distribution additive manufacturing

高延性水泥基材料(ECC)开裂后渗透性研究综述

在线全文

学校读者我要写书评

暂无评论

水利发展研究 2024年第6期24卷 59-64页

作者：王振波周潮王家赫周荆韬中国矿业大学(北京)力学与土木工程学院北京100083 中国铁道科学研究院集团有限公司北京100081

高延性水泥基材料(ECC)是突破了传统混凝土脆性及应变软化属性的变革性的工程结构材料,该材料的拉伸延性与裂纹控制功能决定其适用于构件拉应力区带裂纹服役。开裂ECC的裂纹宽度对于工程耐久性至关重要,如何在保留材料延性的同时更有效... 详细信息

高延性水泥基材料(ECC)是突破了传统混凝土脆性及应变软化属性的变革性的工程结构材料,该材料的拉伸延性与裂纹控制功能决定其适用于构件拉应力区带裂纹服役。开裂ECC的裂纹宽度对于工程耐久性至关重要,如何在保留材料延性的同时更有效地降低裂纹宽度是进一步提升ECC耐久性的关键。文章总结了该材料自研发以来取得的多种裂纹调控方法,指出其裂宽自控能力与延性的不匹配问题,分析了裂纹宽度、纤维掺量、纤维混杂等因素对开裂水泥基材料渗透性的影响,综述了ECC材料独特的开裂渗透规律及其理论预测模型,进一步提出混杂高模量纤维协同聚乙烯醇纤维调控微裂纹的方法,以期为ECC开裂抗渗性与延性的匹配设计、ECC结构的耐久性提升提供借鉴。

关键词：高延性水泥基材料 ECC 裂纹控制渗透性混杂纤维

New Knowledge Network Evaluation Method for Design Rationale Management

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2015年第1期28卷 173-186页

作者： JING Shikai ZHAN Hongfei LIU Jihong WANG Kuan JIANG Hao zhou jingtao School of Mechanical Engineering Beijing Institute of Technology Shanghai Aircraft Design and Research Institute School of Mechanical Engineering and Automation Beihang University School of Mechanical Engineering Northwestern Polytechnical University

Current design rationale （DR） systems have not demonstrated the value of the approach in practice since little attention is put to the evaluation method of DR knowledge. To systematize knowledge management process for future computer-aided DR applications, a prerequisite is to provide the measure for the DR knowledge. In this paper, a new knowledge network evaluation method for DR management is presented. The method characterizes the DR knowledge value from four perspectives, namely, the design rationale structure scale, association knowledge and reasoning ability, degree of design justification support and degree of knowledge representation conciseness. The DR knowledge comprehensive value is also measured by the proposed method. To validate the proposed method, different style of DR knowledge network and the performance of the proposed measure are discussed. The evaluation method has been applied in two realistic design cases and compared with the structural measures. The research proposes the DR knowledge evaluation method which can provide object metric and selection basis for the DR knowledge reuse during the product design process. In addition, the method is proved to be more effective guidance and support for the application and management of DR knowledge.

关键词： design rationale knowledge reasoning justification support decision support knowledge network evaluation

基于多元统计分析评价不同茶树品种的绿茶适制性

在线全文

学校读者我要写书评

暂无评论

食品科学 2024年第3期45卷 9-15页

作者：王欢欢袁丽萍雷震东杨淑雅李玉川周敬涛覃信雪余志倪德江陈玉琼华中农业大学果蔬园艺作物种质创新与利用全国重点实验室湖北武汉430070 华中农业大学园艺林学学院湖北武汉430070

采用主成分分析和多元线性回归分析法考察不同茶区优选区域适制茶树品种的绿茶适制性。本研究以种植于同一区域的63个茶树品种鲜叶为原料,按同一加工工艺加工成烘青绿茶,分析其感官品质、主要理化品质(茶多酚、游离氨基酸、水浸出物和... 详细信息

采用主成分分析和多元线性回归分析法考察不同茶区优选区域适制茶树品种的绿茶适制性。本研究以种植于同一区域的63个茶树品种鲜叶为原料,按同一加工工艺加工成烘青绿茶,分析其感官品质、主要理化品质(茶多酚、游离氨基酸、水浸出物和叶绿素)和色度值(L*、a*、b*),结合主成分分析和多元线性回归分析,评价供试品种的绿茶适制性及其主要影响因子。结果表明,不同品种绿茶叶绿素含量的变异系数最大(26.7%),其次是干茶色度值a*值(22.2%)、汤色(17.1%)和干茶色泽评分(16.2%)。各指标相关性分析表明,茶多酚含量与干茶色泽、汤色和叶底色泽之间,干茶叶绿素含量、|a*|值、b*值与干茶色泽之间,干茶叶绿素含量、|a*|与叶底色泽之间,干茶|a*|值、b*值与汤色之间极显著相关(P<0.01)。主成分分析结果表明,前5个主成分贡献率达76.895%,第1主成分贡献率为31.918%,主要指向色泽品质。通过前5个主成分构建评价模型,得到排名前10的品种包括:中茶108、乌牛早、平阳特早、蒙山9号、薮北种、福鼎大白、鸠坑16号、福鼎大毫、茂绿、龙井43。以主要理化品质和感官评价总分为对象进行多元线性回归分析,得到回归函数为:Y=68.668+5.174x,其中Y为感官评分总分,x为|a*|值,R2为0.313(P<0.001)。以此函数得到排名前10的品种与主成分分析结果高度一致,表明a*值是评定绿茶适制品种的重要指标,可作为绿茶适制品种筛选的重要依据。

关键词：绿茶茶树品种适制性综合评价

Formatted PVDF in lamellar composite solid electrolyte for solidstate lithium metal battery

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第6期17卷 5159-5167页

作者： Xinji Zhang Yafang Zhang Shiyue zhou Jingchuan Dang Chenye Wang Wenjia Wu jingtao Wang School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China

Solid polymer electrolytes(SPEs)hold great application potential for solid-state lithium metal battery because of the excellent interfacial contact and processibility,but being hampered by the poor room-temperature conductivity(~10^(−7)S·cm^(−1))and low lithium-ion transference number(tLi+).Here,a lamellar composite solid electrolyte(Vr-NH_(2)@polyvinylidene fluoride(PVDF)LCSE)withβ-conformation PVDF is fabricated by confining PVDF in the interlayer channel of-NH_(2)modified vermiculite lamellar *** demonstrate that the conformation of PVDF can be manipulated by the nanoconfinement effect and the interaction from channel *** presence of-NH_(2)groups could induce the formation ofβ-conformation PVDF through electrostatic interaction,which serves as continuous and rapid lithium-ion transfer *** a result,a high room-temperature ionic conductivity of 1.77×10^(−4)S·cm^(−1)is achieved,1-2 orders of magnitude higher than most ***,Vr-NH_(2)@PVDF LCSE shows a high tLi+of 0.68 because of the high dielectric constant,~3 times of that of PVDF SPE,and surpassing most of reported *** LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)||Li cell assembled by Vr-NH_(2)@PVDF LCSE obtains a discharge specific capacity of 137.1 mAh·g^(−1)after 150 cycles with a capacity retention rate of 93%at 1 C and 25℃.This study may pave a new avenue for high-performance SPEs.

关键词： solid-state lithium metal battery lamellar composite solid electrolyte β-conformation polyvinylidene fluoride(PVDF) room-temperature ionic conductivity lithium-ion transference number

Study on the interactive deformation of bone needles and circum-pelvic soft tissue

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

High Technology Letters 2024年第3期30卷 297-303页

作者： ZHANG Famin LEI jingtao School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444P.R.China Shanghai Key Laboratory of Intelligent Manufacturing and Robotics Shanghai 200444 P.R.China

During the robot-assisted pelvic fracture reduction,the needle-tissue interactive deformation characteristic is not clear,which affects the accuracy of robotic *** this paper,a layered rig-id-flexible coupling model is proposed,and the needle-tissue interactive deformation under the load-ing is analyzed by the Rayleigh-Ritz method,in accordance with the principle of minimum potential *** pelvic musculoskeletal tissue is reversely reconstructed,and the structure of the bone is segmented into cancellous bone and cortical *** Mooney-Rivlin five-parameter hyperelastic model is used to simulate muscle,and the Ogden hyperelastic model is used to simulate adipose *** element simulation is performed by loading different magnitudes of *** accuracy of the rigid-flexible coupling model is 0.432 mm,which indicates the correctness of the needle-tis-sue interactive deformation theory analysis.

关键词： pelvic fracture reduction rigid-flexible coupling needle-tissue interactive de-formation