检索结果-南通市图书馆

High Voltage 2024年第1期9卷 46-55页

作者： Yan yang Xueyang bai Yuxing Lei Kai Liu Guangning wu School of Electrical Engineering Southwest Jiaotong UniversityChengduChina

The lifetime model of turn-to-turn insulation in inverter-fed motors is studied.A lifetime model has been built by considering the effect of inverter-generated high voltage rise rate(dv/dt up to 20 V/ns).This model is followed by the generalised probabilistic model,in which the lifetime is proportional to the nth power of the voltage rise ***,by investigating the effect of voltage rise rate on the partial discharge characteristics,it is found that the effect of voltage rise rate on the charge transport process in a voltage cycle is similar to that of the voltage *** enhanced partial discharge activity and induced charges are responsible for accelerated ageing and thus determine the final lifetime of turn-to-turn *** this case,the generalised probabilistic electric lifetime model is applicable to the voltage rise rate as well as the voltage amplitude.

关键词： lifetime inverter insulation

罗哌卡因联合右美托咪定对剖宫产产妇镇痛效果、术后恢复和血清炎症因子的影响

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

川北医学院学报 2024年第3期39卷 375-378页

作者：侯桂婷李丹张金金杨百武安徽医科大学附属宿州医院·宿州市立医院麻醉科安徽宿州234000

目的:探讨罗哌卡因联合右美托咪定对剖宫产产妇镇痛效果和术后恢复的影响。方法:按镇痛方案不同,将行116例剖宫产术的产妇分为对照组与试验组,每组各58例。对照组使用罗哌卡因+舒芬太尼镇痛;试验组使用罗哌卡因+右美托咪定镇痛。分别于... 详细信息

目的:探讨罗哌卡因联合右美托咪定对剖宫产产妇镇痛效果和术后恢复的影响。方法:按镇痛方案不同,将行116例剖宫产术的产妇分为对照组与试验组,每组各58例。对照组使用罗哌卡因+舒芬太尼镇痛;试验组使用罗哌卡因+右美托咪定镇痛。分别于术后3、6、12、24、及48 h,对产妇的疼痛程度进行评估;记录产妇术后镇痛泵使用情况;记录两组产妇阻滞时效和术后恢复相关指标;检测产妇术前及术后24 h血清白细胞介素6(IL-6)和肿瘤坏死因子α(TNF-α)水平;记录产妇术后48 h内不良反应发生情况。结果:两组术后3~48 h各时间点VAS评分、首次镇痛按压时间及术后48 h内镇痛泵按压次数差异均无统计学意义(P>0.05)。与对照组比较,试验组腰麻感觉阻滞达到最高平面经历的时间、感觉恢复时间较长(P0.05)。与对照组相比,试验组首次肛门排气时间、泌乳始动时间均明显提前(P<0.05),48 h哺乳次数增多(P<0.05)。与对照组比较,试验组术后24 h血清IL-6、TNF-α水平更低(P<0.05),术后48 h内恶心呕吐发生率、皮肤瘙痒发生率更低(P<0.05)。结论:与罗哌卡因联合舒芬太尼比较,在腰硬联合麻醉中使用罗哌卡因联合右美托咪定也能够提供确切镇痛效果,且可减少不良反应,更能促进产妇术后恢复。

关键词：剖宫产腰硬联合麻醉罗哌卡因去阿片化镇痛右美托咪定

A cloud-edge-device collaborative offloading scheme with heterogeneous tasks and its performance evaluation

在线全文

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2024年第5期25卷 664-684页

作者： Xiaojun bai yang ZHANG Haixing wu Yuting WANG Shunfu JIN School of Information Science and Engineering Yanshan UniversityQinhuangdao 066004China Key Laboratory for Computer Virtual Technology and System Integration of Hebei Province Yanshan UniversityQinhuangdao 066004China

How to collaboratively offload tasks between user devices,edge networks(ENs),and cloud data centers is an interesting and challenging research *** this paper,we investigate the offoading decision,analytical modeling,and system parameter optimization problem in a collaborative cloud-edge device environment,aiming to trade off different performance *** to the differentiated delay requirements of tasks,we classify the tasks into delay-sensitive and delay-tolerant *** meet the delay requirements of delay-sensitive tasks and process as many delay-tolerant tasks as possible,we propose a cloud-edge device collaborative task offoading scheme,in which delay-sensitive and delay-tolerant tasks follow the access threshold policy and the loss policy,*** establish a four-dimensional continuous-time Markov chain as the system *** using the Gauss-Seidel method,we derive the stationary probability distribution of the system ***,we present the blocking rate of delay-sensitive tasks and the average delay of these two types of *** experiments are conducted and analyzed to evaluate the system performance,and numerical simulations are presented to evaluate and validate the effectiveness of the proposed task offloading ***,we optimize the access threshold in the EN buffer to obtain the minimum system cost with different proportions of delay-sensitive tasks.

关键词： Edge computing Ofloading scheme Cloud-edge device collaboration Markov chain Cost function

Flow characteristics of radial inflow in impeller rear cavity with baffle plate

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第2期37卷 270-282页

作者： yang bai Xiang LUO Dongdong LIU Zeyu wu Xiaoqiang ZHANG Sipeng WANG Research Institute of Aero-Engine Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBeijing 100191China

The research purpose of this paper is to explore the influence of the baffle plate on the airflow in the rear cavity of the centrifugal impeller and optimize the performance of the secondary air system’s air bleed *** this paper,a comprehensive experimental study was carried out on the flow characteristics in the impeller rear cavity with baffle *** windage torque,flow structure and pressure drop between inlet and outlet were measured *** experiment was carried out with the condition that the range of rotational Reynolds number was from 8.33×10^(5)to 22.2×10^(5)and the range of mass flow rate coefficient was from 0.92×10^(4)to 2.92×10^(4).The results show that the static cavity and the narrow stator-rotor cavity formed by the baffle plate effectively suppress the overall swirl coefficient in the ***,the static pressure and total pressure drop in the rotor-stator cavity were *** influence of the baffle plate on the windage torque of the rotary disk is related to the turbulence *** large turbulence parameters,the windage torque would be reduced with baffle plate,while under small turbulence parameters,the baffle plate would increase with baffle *** general,the baffle plate can improve the flow capacity and optimize the bleed air performance with proper structure and operation conditions.

关键词： Impeller rear cavity Baffle plate Flow structure Windage torque Pressure drop

Structural disruption of melanin-like polymers with boosted UV protection

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第5期67卷 1653-1663页

作者： Zhen yang Xianheng Wang Wanjie bai Zikun Zou Haoxing wu Yiwen Li Department of Radiology Huaxi MR Research CenterFunctional and Molecular Imaging Key Laboratory of Sichuan ProvinceNational Clinical Research Center for GeriatricsWest China HospitalSichuan UniversityChengdu 610041China College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065China

Manipulating the energy structure of materials represents an efficient way to regulate their light absorption behaviors. For example, constructing donor-acceptor(D-A) structures to increase the polarizability and reduce the energy bandgap of local molecules has been widely used in the field of organic photovoltaics with ordered structures. Remarkably, even in disordered and chaotic systems such as melanin-like polydopamine(PDA), visible and near-infrared light absorption can be significantly improved using this strategy. However, there has been a noticeable dearth of research on the ultraviolet(UV) light absorption regulation of bioinspired polymers with disordered and chaotic architectures by tailoring the D-A microstructures. In this study, a series of benzoheterocyclic molecules with strong electron-donating features screened by molecular simulation calculations were involved in disrupting the D-A structures within PDA. The destruction of D-A structures promoted the increase of the energy band gap and finally boosted the UV absorption of PDA. The resulting PDA nanoparticles with enhanced UV absorption were further employed to fabricate UV shielding composite films to protect the growth of plants from harmful UV radiation. This research may open up new avenues for structural disruption of bioinspired polymers for enhanced photoprotection applications.

关键词： melanin-like polymers polydopamine D-A structure UV absorption photoprotection

Carbon-based interface engineering and architecture design for high-performance lithium metal anodes

在线全文

学校读者我要写书评

暂无评论

Carbon Energy 2024年第1期6卷 207-235页

作者： Na Zhu Yuxiang yang Yu Li Ying bai Junfeng Rong Chuan wu SINOPEC Research Institute of Petroleum Processing Co. Ltd.BeijingChina Beijing Key Laboratory of Environmental Science and Engineering School of Materials Science and EngineeringBeijing Institute of TechnologyBeijingChina yangtze Delta Region Academy of Beijing Institute of Technology JiaxingChina

Metallic lithium(Li)is considered the“Holy Grail”anode material for the nextgeneration of Li batteries with high energy density owing to the extraordinary theoretical specific capacity and the lowest negative electrochemical ***,owing to inhomogeneous Li-ion flux,Li anodes undergo uncontrollable Li deposition,leading to limited power output and practical *** materials and their composites with controllable structures and properties have received extensive attention to guide the homogeneous growth of Li to achieve high-performance Li *** this review,the correlation between the behavior of Li anode and the properties of carbon materials is ***,we review emerging strategies for rationally designing high-performance Li anodes with carbon materials,including interface engineering(stabilizing solid electrolyte interphase layer and other functionalized interfacial layer)and architecture design of host carbon(constructing three-dimension structure,preparing hollow structure,introducing lithiophilic sites,optimizing geometric effects,and compositing with Li).Based on the insights,some prospects on critical challenges and possible future research directions in this field are *** is anticipated that further innovative works on the fundamental chemistry and theoretical research of Li anodes are needed.

关键词： carbon materials dendrites hosts interfacial layers Li metal anodes

Surficial modification enabling planar Al growth toward dendrite-free metal anodes for rechargeable aluminum batteries

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

Science China Chemistry 2024年第4期67卷 1341-1351页

作者： Wenhao Liu Yu Li Bo Long Haoyi yang Lumin Zheng Ying bai Feng wu Chuan wu School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China yangtze Delta Region Academy of Beijing Institute of Technology Jiaxing 314019China

Al metal possesses ultrahigh theoretical volumetric capacity of 8,040 m Ah cm^(-3),and gravimetric capacity of 2,980 m Ah g^(-1),and thus is highly attractive for electrochemical energy ***,it suffers from several issues,such as the dendrite formation,during Al stripping-deposition cycling,which has been verified to account for the short circuit and limited cyclic ***,we use a facile and applicable method to in-situ reconstruct the Al anode surface with F-Al-O chemical bonds,which could preferentially induce the planar growth of Al along the interface plane,thus leading to the dendrite-free morphology evolution during the *** from F-Al-O chemical bonds on the surface of Al anodes,long lifespan of symmetric cells can be realized even under 1 m A cm^(-2)and 1 m Ah cm^(-2).Coupling the F-Al anode with graphite-based cathodes,high-voltage dual-ion Al metal batteries can be achieved with long-term cycle stability up to 1,200 cycles(at 0.5 m A cm^(-2)),surpassing the counterparts using pristine Al metal ***,the effectiveness of this surficial modification strategy is also elucidated with the aid of theoretical *** work provides novel insights on low-cost and facile strategies against the Al dendrite growth in aluminum batteries.

关键词： rechargeable aluminum batteries Al metal anode Al dendrite dual-ion batteries surficial modification

同方期刊数据库

Experimental and computational investigation on flow characteristics of rotating cavities with high inlet pre-swirl axial throughflow

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 276-293页

作者： Sipeng WANG Xiang LUO Linji GUO Zeyu wu yang bai Zongchao LI Lichun MA School of Energy and Power Engineering Beihang UniversityBeijing 100191China Research Institude of Aero-Enigine Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China Shenyang Aeroengine Research Institute Aero Engine Corporation of ChinaShenyang 110015China

As an integral part of the internal air system of aero-engines,the axial throughflow of the cooling air can interact with the cavity flow between the rotating compressor disks,forming a threedimensional,unsteady,and unstable flow *** flow characteristics in an engine-like rotating multi-stage cavity with throughflow were investigated using particle image velocimetry,flow visualization technology and three-dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS)*** focus of current research was to understand the distribution of the mean swirl ratio and its variation with a wide range of non-dimensional parameters in the co-rotating cavity with high inlet pre-swirl axial *** maximum axial Reynolds number and rotational Reynolds numbers could reach 4.41×10^(4)and 1.24×10^(6),*** velocity measurement results indicate that the mean swirl ratio is greater than 1 and decreases with an increase in the radial *** flow structure is dominated by the Rossby number,and two different flow patterns (flow penetration and flow stratification) are identified and confirmed by flow visualization *** the absence of buoyancy,the flow penetration caused by the precession of the throughflow makes it easier for the throughflow to reach a high radius *** consistency of results between measurements and numerical calculations is *** study provides a theoretical basis and data support for toroidal vortex breakdown,which is of practical significance for the design of high-pressure compressor cavities.

关键词： Compressor Axial throughflow Rotating cavity flow Particle image velocimetry Unsteady RANS Flow pattern

Metal-organic framework and its composites modulate macrophage polarization in the treatment of inflammatory diseases

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第5期35卷 45-56页

作者： Feifei Wang Hang Yao Xinyue wu Yijian Tang yang bai Hui Chong Huan Pang School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China School of Pharmacy Changzhou UniversityChangzhou 213164China State Key Laboratory of Coordination Chemistry Nanjing UniversityNanjing 210023China

Metal-organic framework(MOF)is a periodic sexual network structure with large surface area and high porosity,which is assembled by inorganic nodes and organic ligands through coordinate covalent *** have the advantages of controllable pore size and shape,large specific surface area,easy modification and more active *** addition,MOF based nanoenzymes display excellent enzyme catalytic activity due to their special structure and multiple exposed metal active sites,controlling the production of reactive oxygen species(ROS)in cells or the body,and thus regulating the polarization of *** article reviews the mechanism of MOF material regulating macrophage polarization and the function of macrophages with different *** utilizing the excellent properties of MOFs and the advantages of combining them with bioactive materials,we have discovered their excellent applications in the treatment of inflammatory ***,we discussed the current challenges and prospects faced by MOF based composite *** expect that the research in this developing field will play a more important role in combating inflammatory diseases in the field of nanomedicine.

关键词： Metal-organic framework Inflammation Macrophage polarization Reactive oxygen species Nanozyme activity

Effect of stress-relief annealing on thermal fatigue cracks for die-casting die steels

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2024年第5期31卷 1164-1176页

作者： Zhi-xiong bai Xiao-chun wu School of Materials Science and Engineering Shanghai UniversityShanghai200444China

The effect of stress-relief annealing at different stages of thermal fatigue tests on crack growth was investigated using a self-built thermal cycle *** results showed that annealing could limit crack expansion *** reduced dislocation density and released the accumulation of residual *** addition,the strain accumulation in carbides was reduced by this *** was also found that double annealing was even more effective at inhibiting crack expansion compared to single stress-relief *** 1000 cycles,the maximum crack length was reduced by 31.1%and 45.2%for the samples after using the optimal single and double annealing processes,*** single stress-relief annealing,earlier annealing provides more benefit in delaying crack ***,effective double stress-relief annealing requires a suitable time interval between the annealing ***,after 800 cycles,surface hardness decreased significantly accompanied by an increase in the size and number of carbides,and cracks expanded predominantly along grain boundaries.

关键词： Thermal fatigue Steel Carbide Stress-relief annealing Dislocation Residual stress