检索结果-南通市图书馆

聚酚氧树脂/酚醛树脂混合物用于制备覆膜砂的研究

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

铸造技术 2021年第1期42卷 5-7页

作者：钟飞升张雅丹常成张希兴李家波冀运东彰武县联信铸造硅砂有限公司辽宁彰武123200 武汉理工大学材料科学与工程学院湖北武汉430070

聚酚氧树脂具备高韧性高软化点的特点,其与热塑性酚醛树脂共混可以显著提高酚醛树脂的韧性,提高常温强度和热强度,并改善覆膜砂溃散性。将聚酚氧树脂与酚醛树脂共混制备覆膜砂,实验结果表明,聚苯氧树脂添加10%时,覆膜砂拉伸强度提高15.... 详细信息

聚酚氧树脂具备高韧性高软化点的特点,其与热塑性酚醛树脂共混可以显著提高酚醛树脂的韧性,提高常温强度和热强度,并改善覆膜砂溃散性。将聚酚氧树脂与酚醛树脂共混制备覆膜砂,实验结果表明,聚苯氧树脂添加10%时,覆膜砂拉伸强度提高15.2%,弯曲强度提高12.8%,熔点提高3℃,溃散率提高提高20%,在铝合金铸件上面具有较好的应用前景。

关键词：聚苯氧树脂覆膜砂溃散性共混

Framework and development of data-driven physics based model with application in dimensional accuracy prediction in pocket milling

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2021年第6期34卷 162-177页

作者： Zhanying CHEN liping WANG jiabo ZHANG Guoqiang GUO Shuailei FU Chao WANG Xuekun li Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China State Key Lab of Tribology Tsinghua UniversityBeijing 100084China Beijing Spacecrafts China Academy of Space TechnologyBeijing 100094China Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China

In the manufacturing of thin wall components for aerospace industry,apart from the side wall contour error,the Remaining Bottom Thickness Error(RBTE)for the thin-wall pocket component(*** shell)is of the same importance but overlooked in current *** the RBTE reduces by 30%,the weight reduction of the entire component will reach up to tens of kilograms while improving the dynamic balance performance of the large *** RBTE control requires the off-process measurement of limited discrete points on the component bottom to provide the reference value for *** leads to incompleteness in the remaining bottom thickness control and redundant measurement in *** this paper,the framework of data-driven physics based model is proposed and developed for the real-time prediction of critical quality for large components,which enables accurate prediction and compensation of RBTE value for the thin wall *** physics based model considers the primary root cause,in terms of tool deflection and clamping stiffness induced Axial Material Removal Thickness(AMRT)variation,for the RBTE *** to incorporate the dynamic and inherent coupling of the complicated manufacturing system,the multi-feature fusion and machine learning algorithm,*** Principal Component Analysis(kPCA)and kernel Support Vector Regression(kSVR),are incorporated with the physics based ***,the proposed data-driven physics based model combines both process mechanism and the system disturbance to achieve better prediction *** final verification experiment is implemented to validate the effectiveness of the proposed method for dimensional accuracy prediction in pocket milling,and the prediction accuracy of AMRT achieves 0.014 mm and 0.019 mm for straight and corner milling,respectively.

关键词： Data-driven Physics based model Thin-wall component Pocket milling Remaining bottom thickness error

Hydrodynamics study of dolphin’s self-yaw motion realized by spanwise flexibility of caudal fin

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean Engineering and Science 2022年第3期7卷 213-224页

作者： Zhihan li Dan Xia jiabo Cao Weishan Chen Xingsong Wang School of Mechanical Engineering Southeast UniversityNanjingJiangsu 211189China State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150080China

The hydrodynamic performance of the virtual underwater vehicle under self-yaw is investigated numerically in this paper,we aim to explore the fluid laws behind this plane motion achieved by the bionic flexibility,especially the spanwise flexibility of the caudal *** kinematics of the chordwise flexible body and the spanwise flexible caudal fin are explored through dynamic mesh technology and user-defined functions(UDF).The 3-D Navier-Stokes equations are applied to simulate the viscid fluid surrounding the bionic *** study focuses on quantitative problems about the fluid dynamics behind the specific motion law,including speed of movement,energy loss and working *** current results show that the self-yaw can be composed of two motions,autonomous propulsion and active *** addition,the degree of the flexible caudal fin can produce different yaw *** chordwise phase differenceФis dominant in the propulsion function,while the spanwise phase differenceδhas a more noticeable effect on the steering *** pressure distribution on the surface of the dolphin and the wake vortex generated in the flow field reasonably reveal the evolution of *** properly turns out that the dolphin can combine the spanwise flexible caudal fin and the chordwise flexible body to achieve self-yaw motion.

关键词： Self-yaw dolphin Spanwise flexibility Caudal fin Numerical simulation Hydrodynamic performance

Dataflow Management in the Internet of Things: Sensing,Control, and Security

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

Tsinghua Science and Technology 2021年第6期26卷 918-930页

作者： Dawei Wei Huansheng Ning Feifei Shi Yueliang Wan jiabo Xu Shunkun Yang li Zhu School of Computer and Communication Engineering University of Science and Technology BeijingBeijing 100083China Beijing Engineering Research Center for Cyberspace Data Analysis and Applications Beijing 100083China Run Technologies Co. Ltd.Beijing 100192China School of Information Engineering Xinjiang Institute of EngineeringUrumqi 830023China School of Reliability and Systems Engineering Beihang UniversityBeijing 100191China Northern Cloud Research Team Engineering University of PAPXi'an 710086China

The pervasiveness of the smart Internet of Things(IoTs) enables many electric sensors and devices to be connected and generates a large amount of dataflow. Compared with traditional big data, the streaming dataflow is faced with representative challenges, such as high speed, strong variability, rough continuity, and demanding timeliness, which pose severe tests of its efficient management. In this paper, we provide an overall review of IoT dataflow management. We first analyze the key challenges faced with IoT dataflow and initially overview the related techniques in dataflow management, spanning dataflow sensing, mining, control, security, privacy protection,etc. Then, we illustrate and compare representative tools or platforms for IoT dataflow management. In addition,promising application scenarios, such as smart cities, smart transportation, and smart manufacturing, are elaborated,which will provide significant guidance for further research. The management of IoT dataflow is also an important area, which merits in-depth discussions and further study.

关键词： Internet of Things(IoTs) dataflow security privacy management

在线全文

学校读者我要写书评

暂无评论

烧结陶粒砂在树脂砂中的应用效果

铸造技术 2021年第1期42卷 25-28页

作者：钟飞升张雅丹常成张希兴李家波冀运东彰武县联信铸造硅砂有限公司辽宁阜新123200 彰武联信金莹铸造材料有限公司辽宁阜新123200 武汉理工大学材料科学与工程学院湖北武汉430070

烧结陶粒砂是由耐火粉料、粘接剂、助熔剂等粉料,经过造粒、干燥、筛分、烧结制成。具有耐火度高,球形度高等优点。主要应用于覆膜砂,其他应用较少。结果表明,通过烧结陶粒砂实际应用于三乙胺冷芯盒工艺制芯发现,烧结陶粒砂表面有孔洞,... 详细信息

烧结陶粒砂是由耐火粉料、粘接剂、助熔剂等粉料,经过造粒、干燥、筛分、烧结制成。具有耐火度高,球形度高等优点。主要应用于覆膜砂,其他应用较少。结果表明,通过烧结陶粒砂实际应用于三乙胺冷芯盒工艺制芯发现,烧结陶粒砂表面有孔洞,造成冷芯盒强度低。烧结陶粒砂在覆膜砂中应用,具有强度高,膨胀率低的优势。

关键词：烧结陶粒砂孔隙强度低冷芯盒工艺

自我感知老化在社区老年人衰弱和认知功能间的中介作用

在线全文

学校读者我要写书评

暂无评论

中华行为医学与脑科学杂志 2023年第3期32卷 250-256页

作者：王飞飞姚桂英侯秀珍孙俊俊张会敏王华吴慧敏李佳波周宁罗艳艳新乡医学院护理学院新乡453003 新乡市中心医院护理部新乡453000 新乡市直机关医院社区卫生服务中心新乡453000

目的:探讨自我感知老化在社区老年人衰弱和认知功能间的中介作用。方法:2021年2—7月采用衰弱量表、简版自我感知老化量表和简易智能精神状态量表对新乡市528名社区老年人进行调查。根据简易智能精神状态量表总分和文化程度将被试分为... 详细信息

目的:探讨自我感知老化在社区老年人衰弱和认知功能间的中介作用。方法:2021年2—7月采用衰弱量表、简版自我感知老化量表和简易智能精神状态量表对新乡市528名社区老年人进行调查。根据简易智能精神状态量表总分和文化程度将被试分为认知障碍组(文盲≤17分,小学≤20分,初中及以上≤24分,n=74)和认知正常组(n=454)。采用SPSS 25.0进行共同方法偏差检验、描述性统计和相关分析,应用AMOS 24.0构建结构方程模型并采用Bootstrap法进行中介效应检验。结果:(1)社区老年人认知障碍的发生率为14.1%;认知正常组和认知障碍组在年龄、文化程度、患慢性病数目、抑郁方面均差异有统计学意义(χ^(2)=59.21,6.53,9.84,25.47;均P<0.05);在衰弱(χ^(2)=75.65,P<0.001)和自我感知老化(t=77.67,P<0.001)方面均差异有统计学意义。(2)认知障碍组自我感知老化得分[(47.39±8.66)分]高于认知正常组[(38.22±8.24)分](t=77.67,P<0.001);认知障碍组衰弱得分[2.00(1.00,3.00)分]高于认知正常组[0.00(0.00,1.00)分](Z=-8.63,P<0.001)。(3)衰弱与认知功能呈负相关(r=-0.492,P<0.01),与自我感知老化呈正相关(r=0.540,P<0.01),自我感知老化与认知功能呈负相关(r=-0.541,P<0.01);控制年龄、文化程度、患慢性病数目、抑郁等因素后,相关性依然显著(均P<0.01)。(4)自我感知老化在衰弱和认知功能间起部分中介作用,且中介效应占总效应的58.5%。结论:衰弱和自我感知老化对社区老年人认知功能有显著影响,且自我感知老化在社区老年人衰弱和认知功能间起部分中介作用。

关键词：社区老年人衰弱自我感知老化认知功能中介作用

针刺联合拔罐治疗肾气不足型儿童遗尿症临床观察

在线全文

学校读者我要写书评

暂无评论

河北中医 2021年第3期43卷 492-495,520页

作者：李佳钵袁军解晓亚安静路元春张雨佳河北中医学院河北石家庄050091 河北中医学院第一附属医院针灸科河北石家庄050011

目的观察针刺联合拔罐治疗肾气不足型儿童遗尿症的临床疗效。方法将80例肾气不足型遗尿症患儿按照随机数字表法分为2组。治疗组40例予针刺联合拔罐治疗,对照组40例予缩泉丸治疗。2组均治疗10 d为1个疗程,共治疗3个疗程,疗程间休息2 d。... 详细信息

目的观察针刺联合拔罐治疗肾气不足型儿童遗尿症的临床疗效。方法将80例肾气不足型遗尿症患儿按照随机数字表法分为2组。治疗组40例予针刺联合拔罐治疗,对照组40例予缩泉丸治疗。2组均治疗10 d为1个疗程,共治疗3个疗程,疗程间休息2 d。比较2组治疗前后中医症状评分(包括夜间遗尿、形寒肢冷、熟睡不醒及尿清量多)、儿少主观生活质量问卷(ISLQ)评分(包括躯体体验、焦虑体验、抑郁体验、家庭生活、同伴交往、学校生活、生活环境及自我认识)及血浆抗利尿激素(ADH)水平变化情况,2组患儿均治愈后随访6个月,比较复发情况。结果治疗组总有效率95.0%(38/40),复发率10.0%(4/40),对照组分别为75.0%(30/40)、32.5%(13/40),治疗组总有效率明显高于对照组(P<0.05),复发率明显低于对照组(P<0.05)。2组治疗后中医症状夜间遗尿、形寒肢冷、熟睡不醒、尿清量多评分及总分与本组治疗前比较均降低(P<0.05),且治疗组治疗后中医症状各项评分及总分均明显低于对照组(P<0.05)。2组治疗后ISLQ躯体体验、焦虑体验、抑郁体验、家庭生活、同伴交往、学校生活、生活环境、自我认识评分及总分与本组治疗前比较均明显升高(P<0.05),且治疗组治疗后ISLQ各项评分及总分均明显高于对照组(P<0.05)。2组治疗后血浆ADH水平与本组治疗前比较均明显升高(P<0.05),且治疗组治疗后血浆ADH水平明显高于对照组(P<0.05)。结论针刺联合拔罐治疗肾气不足型儿童遗尿症临床疗效确切,可明显改善患儿中医症状,提高生活质量,提高血浆ADH水平,提高临床疗效,且复发率低,操作简单方便。

关键词：夜遗尿症儿童肾气虚针刺疗法拔罐

Face-centered cubic structured RuCu hollow urchin-like nanospheres enable remarkable hydrogen evolution catalysis

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2022年第1期65卷 87-95页

作者： Juntao Zhang jiabo Le Yuanting Dong lingzheng Bu Ying Zhang Jun Cheng Leigang li Xiaoqing Huang State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingbo 315201China

Ruthenium(Ru)is one of the most promising metals for its versatility in driving a wide range of catalytic ***,owing to the intrinsic preference of hexagonal close-packed(hcp)phase for bulk Ru,currently,it is still challenging to construct Ru-based nanomaterials with face-centered-cubic(fcc)phase for optimizing their performance towards potential ***,we report a facile wet-chemical method to directly create unconventional fcc-structured Ru-copper hollow urchin-like nanospheres(fcc-RuCu HUNSs)as a class of efficient pH-universal hydrogen evolution reaction(HER)***,this synthetic strategy can be expanded to prepare other fcc-Ru-based alloy ***,the novel fcc-RuCu HUNSs exhibit superior HER performance with the overpotential of only 25,34,40,and 26 m V to reach the current density of 10 mA cm^(-2)in 0.5 M H_(2)SO_(4),0.05 M H_(2)SO_(4),0.1 M KOH,and 1 M KOH,respectively,much lower than those of hcpRuCu HUNSs and commercial Pt/*** functional theory(DFT)calculations further indicate that their excellent pH-universal HER performance results from the optimized adsorption free energy of H and work *** work highlights the importance of phase control to design high-efficiency nanocatalysts for relevant catalytic reactions in energy conversion.

关键词： ruthenium phase control face-centered cubic hydrogen evolution catalysis pH-universal

The hydrodynamics of self-rolling locomotion driven by the flexible pectoral fins of 3-D bionic dolphin

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean Engineering and Science 2022年第1期7卷 29-40页

作者： Zhihan li Dan Xia Xufeng Zhou jiabo Cao Weishan Chen Xingsong Wang School of Mechanical Engineering Southeast UniversityNanjing 211189China State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150080China

The novel autonomous rolling performance is realized by the pair of pectoral fins of a three-dimensional(3-D)bionic dolphin in this paper numerically.3-D Navier-Stokes equations are employed to simulate the viscous fluid around the bionic *** effect of self-rolling manoeuvrability is ex-plored using the dynamic mesh technology and user-defined function(UDF).By varying the parameter ratios,the interaction of flexible pectoral fins is divided into two motion modes,amplitude differential and frequency differential *** the primary driving source,the differential motion of a pair of pec-toral fins can effectively provide the rolling torque,and the trajectory of the entire rolling process is approximately the clockwise *** results demonstrate that the rolling angular velocity and driving torque in the steady state can be improved by increasing parameter ratios,and the rolling efficiency can reach the maximum under the optimal parameter ***,different parameter ratios do not af-fect the rolling radius of the self-rolling *** evolution process around the pair of pectoral fins is shown by the flow structures in self-rolling swimming,reasonably revealing that self-rolling locomotion is produced by the pressure and wake vortices surrounding the pair of pectoral fins,and the wake struc-tures depend primarily on the variation of parameter *** properly turns out that the application of the pair of pectoral fins can realize the self-rolling performance through parameter differential modes.

关键词： Self-rolling dolphin Parameter differential mode Numerical simulation Hydrodynamic performance Flow structures