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Co-enhancement of thermal conduction and radiation through morphologies controlling of graphene functional layer for chip thermal management

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Nano Research 2024年第10期17卷 8885-8892页

作者： Shuting Cheng Kun Wang Shichen Xu Yi Cheng Ruojuan liu Kewen Huang Hao Yuan Wenjuan Li Yuyao Yang Fushun Liang Fan Yang Kangyi Zheng Zhiwei Liang Ce Tu mengxiong liu Xiaomin Yang Jingnan Wang Xuzhao Gai Yuejie Zhao Xiaobai Wang Yue Qi Zhongfan liu State Key Laboratory of Heavy Oil Processing College of ScienceChina University of PetroleumBeijing 102249China Centre for Nanochemistry Beijing Science and Engineering Centre for NanocarbonsBeijing National Laboratory for Molecular SciencesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Beijing Graphene Institute(BGI) Beijing 100095China College of Energy Soochow Institute for Energy and Materials Innovations(SIEMIS)Jiangsu Provincial Key Laboratory for Advanced Carbon Materials and Wearable Energy TechnologiesSoochow UniversitySuzhou 215006China Department of Chemistry College of Chemistry and Materials EngineeringBeijing Technology and Business UniversityBeijing 100048China

With the continuous advancements in electronics towards downsizing and integration,efficient thermal dissipation from chips has emerged as a critical factor affecting their lifespan and operational *** fan-less chip cooling system has two critical interfaces for thermal transport,which are the contact interface between the base and the chip dominated by thermal conduction,and the surface of the fins dominated by thermal *** different thermal transfer modes of these two critical interfaces pose different requirements for thermal management *** the study,a novel approach was proposed by developing graphene thermal transport functional material whose morphology could be intentionally designed via reformed plasmaenhanced chemical vapor deposition(PECVD)methods to meet the diverse requirements of heat transfer ***,graphene with multilevel branching structure of vertical graphene(BVG)was fabricated through the hydrogenassisted PECVD(H_(2)-PECVD)strategy,which contributed a high emissivity of~*** was deposited on the fins’surface and functioned as the radiation enhanced layer to facilitate the rapid radiation of heat from the heat sinks into the surrounding ***,the well-oriented vertical graphene(OVG)was successfully prepared through the vertical electric field-assisted PECVD process(EF-PECVD),which showed a high directional thermal conductivity of~53.5 W·m^(-1)·K^(-1).OVG was deposited on the contact interface and functioned as the thermal conduction enhanced layer,allowing for the quick transmission of heat from the chip to the heat *** this design concept,the two critical interfaces in the chip cooling system can be jointly enhanced,resulting in a remarkable cooling efficiency enhancement of~30.7%,demonstrating that this novel material possessed enormous potential for enhancing the performance of cooling ***,this research not only provided new design concepts for the cooling system

关键词： chip thermal management thermal conduction thermal radiation graphene morphology control

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斐济探奇

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当代世界 2005年第7期 52-55页

作者：刘梦熊

斐济由1000多个岛屿组成,其中有人居住的约有300余个.最大的维提岛有我国的海南那么大,像一只在大海中浮游的螃蟹.斐济的国土有18万平方公里,而人口只有74万(其中土著斐济人36万,印度族人34万),每平方公里仅4.1人,是个地广人稀的国家.

关键词：斐济 300 平方居住国土人口

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面向阵型保持的UUV集群绿色动态控位方法研究

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仪器仪表学报 2020年第5期41卷 129-139页

作者：徐健刘梦雄陈光佳李娟陈冬哈尔滨工程大学哈尔滨150001

主从式水下无人航行器(UUV)集群在执行协同观探测任务时,既需要保持在阵地部署的观探测阵型,又需要以较少的能耗完成该任务。首先,对上述过程中的UUV低能耗绿色动态控位及阵型保持需求进行了分析,并针对以上需求设计了面向主从式UUV集... 详细信息

主从式水下无人航行器(UUV)集群在执行协同观探测任务时,既需要保持在阵地部署的观探测阵型,又需要以较少的能耗完成该任务。首先,对上述过程中的UUV低能耗绿色动态控位及阵型保持需求进行了分析,并针对以上需求设计了面向主从式UUV集群阵型保持的绿色动态控位策略。其次,在UUV绿色动态控位策略的主导下,对涉及到的基于粒子群寻优的全局最优推力规划及基于改进广义预测控制的实时滚动优化两种控制方案分别进行了具体的设计。仿真结果表明,相比于传统PID控制,上述控制策略及控制方法能够将控制时间由200 s缩减为60 s,在满足UUV集群协同观探测任务需求的前提下,以更低的能耗完成动态控位任务。

关键词：无人航行器协同阵型保持绿色动态控位粒子群优化预测控制

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河北省碳排放与经济发展的分析——基于EKC曲线与ARIMA模型

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绿色科技 2018年第2期20卷 98-100页

作者：王银刘孟雄长安大学环境科学与工程学院旱区地下水文与生态效应教育部重点实验室陕西西安710054

指出了河北省政府印发《河北省煤炭行业化解过剩生产能实现脱困发展的实施方案》中明确了对煤炭的用量控制,该措施可以有效减少碳排放,因此对河北省1980~2014年的碳排放量进行了分析与预测。采用环境库兹涅茨曲线对河北省1980~2014年的... 详细信息

指出了河北省政府印发《河北省煤炭行业化解过剩生产能实现脱困发展的实施方案》中明确了对煤炭的用量控制,该措施可以有效减少碳排放,因此对河北省1980~2014年的碳排放量进行了分析与预测。采用环境库兹涅茨曲线对河北省1980~2014年的碳排放进行了分析,以SPSS软件为手段,用ARIMA模型对河北省碳排放进行了预测。分析结果表明:河北省碳排放EKC(环境库兹涅茨曲线)呈现的"正U型"。ARIMA模型预测得到2015~2017年河北省的碳排放量分别为78937.4817、72960.5450、65039.9987万t。

关键词：河北省碳排放 EKC曲线 ARIMA模型

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沿空留巷密集钻孔切顶机理及关键参数确定方法

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煤炭科学技术 2024年第2期52卷 23-33页

作者：刘少伟李小鹏朱雯清付孟雄张定山彭博河南理工大学能源科学与工程学院河南焦作454003 煤炭安全生产与清洁高效利用省部共建协同创新中心河南焦作454003 中铁建设集团有限公司北京100176 四川川煤华荣能源有限责任公司四川成都610091

为实现密集钻孔切顶条件下沿空留巷顶板结构安全稳定,研究正常情况与密集钻孔条件下顶板岩层结构受力状况,基于岩石断裂理论和弹性理论分析回采前后顶板密集钻孔孔间围岩受力分布及其破断过程,明确密集钻孔切顶机理及相邻钻孔的孔间集... 详细信息

为实现密集钻孔切顶条件下沿空留巷顶板结构安全稳定,研究正常情况与密集钻孔条件下顶板岩层结构受力状况,基于岩石断裂理论和弹性理论分析回采前后顶板密集钻孔孔间围岩受力分布及其破断过程,明确密集钻孔切顶机理及相邻钻孔的孔间集中应力相互作用机制,推导工作面端头弧形三角板结构巷道侧边界密集钻孔孔间围岩的拉剪应力计算公式。在此基础上,分析不同参数对孔间围岩所受拉剪应力的影响作用,提出沿空留巷密集钻孔切顶关键参数确定方法。研究表明:密集钻孔主要通过回采前后钻孔周围应力条件改变来增加钻孔围岩拉剪应力集中程度,引起孔间裂隙扩张联通,形成切缝线破断关键岩层。回采前钻孔主要受水平挤压应力影响,回采后钻孔受力逐渐转变为采空区顶板回转下沉产生的拉剪应力为主,钻孔孔间围岩状态随之由孔间围岩弱化阶段过渡到孔壁裂纹成形阶段,再转变为孔间围岩破断阶段。密集钻孔孔间围岩所受拉剪应力大小主要取决于关键岩层厚度及钻孔孔径与孔间距之比,与钻孔高度及间距成负相关,与角度及直径正相关。据此提出了密集钻孔关键参数确定方法,并根据龙滩矿3124 N工作面坚硬顶板条件设计了密集钻孔切顶留巷方案,确定钻孔长度为8.3 m,角度为15°,钻孔直径为48 mm,间距为500 mm。留巷后巷道顶帮变形可控且整体稳定性较好,由此可证明密集钻孔布置参数较为合理,密集钻孔关键参数确定方法有效可行。

关键词：沿空留巷切顶留巷密集钻孔弧形三角板孔间应力集中

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Frequency Regulation of VSC-MTDC System with Offshore Wind Farms

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 275-286页

作者： Haoyu liu Chongru liu North China Electric Power University Beijing 102206China

Frequency regulation of voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC)system with offshore wind farms enhances the frequency stability by compensating the power for a disturbed AC ***,it is difficult to reasonably allocate frequency-regulation resources due to a lack of coordination mechanisms between wind farms and the MTDC ***,it is difficult for the frequency control of the wind farms to manage changes in wind speed;and the risk of wind-turbine stalls is ***,based on the kinetic energy of wind turbines and the power margin of the converters,the frequency-regulation capability of wind turbines is evaluated,and a dynamic frequency-support scheme considering the real-time frequency-support capability of the wind turbines and system frequency evolution is proposed to improve the frequency-support performance.A power adaptation technique at variable wind speeds is developed;the active power in the frequency-support stage and restoration stage is switched according to the wind speed.A hierarchical zoning frequency-regulation scheme is designed to use the frequency-regulation resources of different links in the MTDC system with wind *** simulation results show that the novel frequency-regulation strategy maintains frequency stability with wind-speed changes and avoids multiple frequency dips.

关键词： Wind generation voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC) frequency regulation cooperative control adaptive control variable wind speed

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预应力锚索自由段剪切破坏机制研究

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岩石力学与工程学报 2024年第6期43卷 1468-1479页

作者：冯超刘少伟付孟雄吕谦贺德印何亚飞河南理工大学能源科学与工程学院河南焦作454000 安阳工学院土木与建筑工程学院河南安阳455000 河南理工大学煤炭安全生产与清洁高效利用省部共建协同创新中心河南焦作454000

端部锚固型锚索作为一种高效且经济的加固手段,在岩体支护领域应用广泛。端锚锚索自由段剪切破坏是工程实践中常见的一种锚索破坏类型,其破坏机制与全长锚固型锚索有着本质差别,需要进一步深入研究。综合采用实验室试验、理论分析和数... 详细信息

端部锚固型锚索作为一种高效且经济的加固手段,在岩体支护领域应用广泛。端锚锚索自由段剪切破坏是工程实践中常见的一种锚索破坏类型,其破坏机制与全长锚固型锚索有着本质差别,需要进一步深入研究。综合采用实验室试验、理论分析和数值模拟等研究方法,明晰了锚索自由段剪切破坏特征,揭示了预应力锚索自由段板剪切破坏力学机制和细观演化规律。研究结果表明:节理面剪切作用引起锚索内形成耦合增长的轴力和剪力,钢绞线断口同时存在拉伸和剪切破坏2种类型;反弯点处锚索轴力和剪力呈正相关关系,基于拉剪复合破坏准则,较好地解释了锚索剪切破坏力学机制;锚索剪切过程中同时存在拉应力集中区和拉剪复合应力集中区,锚索外缘钢绞线表面剪切损伤导致其较早破坏,锚索内力演化规律证实了锚索剪切破坏属于拉剪复合破坏。研究结果为锚索支护技术的发展提供一定的参考作用。

关键词：岩石力学岩体支护剪切破坏锚索自由段力学模型数值模拟

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A Novel Design of a Pre-separation Panel Structure to Protect Against the Impact of an Explosion in an Aircraft Plenum Chamber

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Acta Mechanica Solida Sinica 2024年第1期37卷 166-180页

作者： Zongxing liu Xiang Yang Jun liu School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China COMAC Shanghai Aircraft Design and Research Institute Shanghai 201210China

To reduce the damage of the pressurizing panel structure of a fuselage caused by an explosion at the“least risk bomb location”in an aircraft structure,a new pre-separation panel structure was designed to resist blast ***,the dynamic strain response and morphology of impact damage of the new pre-separation panel were measured in an impact damage ***,the commercial software LS-DYNA was used to calculate the propagation of the blast shock wave,and the results were compared with empirical equations to verify the rationality of the numerical calculation ***,the fluid–structure coupling method was used to calculate the damage process of the pre-separation panel structure under the impact of an explosion wave and an impact *** calculated results were in good agreement with the test results,which showed the rationality of the calculation method and the *** residual strength of the damaged pre-separation panel was significantly higher than that of the original damaged *** results show that the new pre-separation panel structure is reasonable and has certain significance for guiding the design of plenum chambers with strong resistance to implosion for aircraft fuselages.

关键词： Pre-separation panel structure Explosive response Residual strength Aircraft plenum chamber Least risk bomb location

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Effectiveness and safety of acupuncture in treatment of pregnancyrelated symptoms:a systematic review and Meta-analysis

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Journal of Traditional Chinese Medicine 2024年第1期44卷 16-26页

作者： liu Tingting liu Tongou liu Mingfu School of Traditional Chinese Medicine Clinical Medicine Hubei University of Traditional Chinese MedicineWuhan 430000China First Clinical College of Hubei University of Traditional Chinese Medicine Wuhan 430000China Department of Acupuncture and Tuina Affiliated Hospital of Hubei University of Traditional Chinese MedicineHubei Provincial Hospital of Traditional Chinese MedicineWuhan 430000China

OBJECTIVE:To systematically evaluate the efficacy and safety of acupuncture(AM)in the treatment of pregnancyrelated symptoms such as acute vomiting during ***:We comprehensively searched the available literature up to November 2021,including Pub Med,Embase,Cochrane Library,Chinese Biomedical Literature Database,and China National Knowledge Infrastructure Database,for randomized controlled trials(RCTs)on AM for the treatment of severe vomiting,insomnia,pharyngeal and pelvic pain,mood abnormalities,and dyspepsia during ***:Sixteen RCTs with a cumulative sample size of 1178 cases were *** these,964 patients were included in the *** Meta-analysis results showed that AM was more efficient than Western medicine in treating discomfort during pregnancy[odds ratio(OR)=1.19,95%confidence interval(CI)(1.11,1.28),P<0.01].AM was better than the control group in improving the visual analog scale scores[standard mean difference(SMD)=0.62,95%CI(0.53,0.71),P<0.01].AM was superior to the control group in improving Numerical Rating Scale(NRS)symptom scores[OR=7.31,95%CI(3.36,15.94),P<0.01].There was no significant difference in adverse effects between the AM and sham-AM groups and the analgesic drug group[OR=0.70,95%CI(0.39,1.28),P=0.25],but the treatment and control groups had mild adverse effects with a low ***:AM is more effective than other treatments or pharmacotherapy alone in the treatment of pregnancy-related symptoms,and is relatively ***,the quality of the included trials was rather poor,and high-quality studies are required to confirm our findings.

关键词： acupuncture pregnancy nausea vomiting sleep initiation and maintenance disorders low back pain pelvic pain mood abnormalities Meta-analysis systematic review

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Stochastic Unit Commitment with High-Penetration Offshore Wind Power Generation in Typhoon Scenarios

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 535-546页

作者： Yanqi liu Dundun liu Hongcai Zhang State Key Laboratory of Internet of Things for Smart City and Department of Electrical and Computer Engineering University of MacaoMacao 999078China University of Macao Zhuhai UM Science and Technology Research Institute ZhuhaiChina

To tackle the energy crisis and climate change,wind farms are being heavily invested in across the *** China's coastal areas,there are abundant wind resources and numerous offshore wind farms are being *** secure operation of these wind farms may suffer from typhoons,and researchers have studied power system operation and resilience enhancement in typhoon ***,the intricate movement of a typhoon makes it challenging to evaluate its spatial-temporal *** published papers only consider predefined typhoon trajectories neglecting *** address this challenge,this study proposes a stochastic unit commitment model that incorporates high-penetration offshore wind power generation in typhoon *** adopts a data-driven method to describe the uncertainties of typhoon trajectories and considers the realistic anti-typhoon mode in offshore wind farms.A two-stage stochastic unit commitment model is designed to enhance power system resilience in typhoon *** formulate the model into a mixed-integer linear programming problem and then solve it based on the computationally-efficient progressive hedging algorithm(PHA).Finally,numerical experiments validate the effectiveness of the proposed method.

关键词： Unit commitment two-stage stochastic programming offshore wind farm typhoon

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