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Multiscale engineered hydrogel for solar evaporation with enhanced water transport and purification

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Science China Materials 2024年第8期67卷 2709-2710页

作者： Mingzhan Wang Ronghui wu Shuang zheng Pritzker School of Molecular Engineering University of ChicagoChicagoIL 60637USA Department of Civil Engineering The University of Hong KongHong Kong 999077China

Solar evaporation is emerging as a powerful solution to alleviate the global water shortage *** a recent work published in Nature Water,Liangti Qu and coworkers[1]report a facile method of preparing a graphene/alginate hydrogel(GAH),which not only possesses nearly total rejections to salts,volatile and non-volatile organic compounds,but also exhibits excellent antifouling properties to bacteria and *** the perspective of chemistry,these impressive properties originate from the systematic engineering of the GAH,ranging from the molecular scale to the macroscopic scale.

关键词： volatile hydrogel preparing

Fault Diagnosis Method of Rolling Bearing Based on MSCNN-LSTM

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Computers, Materials & Continua 2024年第6期79卷 4395-4411页

作者： Chunming wu Shupeng zheng Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology Ministry of EducationNortheast Electric Power UniversityJilin132012China Ministry of Education Northeast Electric Power UniversityJilin132012China

Deep neural networks have been widely applied to bearing fault diagnosis systems and achieved impressive success *** address the problem that the insufficient fault feature extraction ability of traditional fault diagnosis methods results in poor diagnosis effect under variable load and noise interference scenarios,a rolling bearing fault diagnosis model combining Multi-Scale Convolutional Neural Network(MSCNN)and Long Short-Term Memory(LSTM)fused with attention mechanism is *** adaptively extract the essential spatial feature information of various sizes,the model creates a multi-scale feature extraction module using the convolutional neural network(CNN)learning *** learning capacity of LSTM for time information sequence is then used to extract the vibration signal’s temporal feature *** parallel large and small convolutional kernels teach the system spatial local *** gathers temporal global features to thoroughly and painstakingly mine the vibration signal’s characteristics,thus enhancing model ***,bearing fault diagnosis is accomplished by using the SoftMax *** experiment outcomes demonstrate that the model can derive fault properties entirely from the initial vibration *** can retain good diagnostic accuracy under variable load and noise interference and has strong generalization compared to other fault diagnosis models.

关键词： Bearing fault diagnosis convolutional neural network short-long-term memory network feature fusion

Impact response and energy absorption of metallic buffer with entangled wire mesh damper

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Defence Technology（防务技术） 2024年第5期35卷 137-150页

作者： Chao zheng Jun wu Mangong Zhang Xin Xue Institute of Metal Rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350116China wuhan Second Ship Design and Research Institute Wuhan 430205China

An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering *** impact response and the energy dissipation mechanism of hat-shaped EWMD under different quasi-static compression deformations(2-7 mm)and impact heights(100-200 mm)are investigated using experimental and numerical *** results demonstrate distinct stages in the quasi-static mechanical characteristics of hat-shaped EWMD,including stiffness softening,negative stiffness,and stiffness *** loss factor gradually increases with increasing compression deformation before entering the stiffness hardening *** impact loads,the hat-shaped EWMD exhibits optimal impact energy absorption when it enters the negative stiffness stage(150 mm),resulting in the best impact isolation effect of metallic ***,the impact energy absorption significantly decreases when hat-shaped EWMD enters the stiffness hardening ***,quasi-static compression analysis after experiencing different impact loads reveals the disappearance of the negative stiffness ***,with increasing impact loads,the stiffness hardening point progressively shifts to an earlier stage.

关键词： Metallic buffer Hat-shaped EWMD Drop impact Energy absorption characteristics Mechanical behavior

Exploring Trade-offs in Thermal Interface Materials:The Impact of Polymer-Filler Interfaces on Thermal Conductivity and Thixotropy

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Chinese Journal of Polymer Science 2024年第7期42卷 916-925,I0006页

作者： Bin Zhang zheng-Li Dou Yong-zheng Zhang Qiang Fu Kai wu College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China

Effective thermal transport across solid-solid interfaces which is essential in thermal interface materials(TIMs),necessitates both optimal thixotropy and high thermal *** role of filler surface modification,a fundamental aspect of TIM fabrication,in the influence of these properties is not fully *** study employs the use of a silane coupling agent(SCA)to modify alumina,integrating experimental approaches with molecular dynamics simulations,to elucidate the interface effects on thixotropy and thermal conductivity in polydimethylsiloxane(PDMS)-based *** findings reveal that the variations of SCAs modify both interface binding energy and transition layer *** interface binding energy restricts macromolecular segmental relaxation near the interface,hindering desirable thixotropy and bond line *** the contrary,the thickness of the transition layer at the interface positively influences thermal conductivity,facilitating the transport of phonons between the polymer and ***,selecting an optimal SCA allows a balance between traditionally conflicting goals of high thermal conductivity and minimal bond line thickness,achieving an impressively low interface thermal resistance of just 2.45-4.29 K·mm^(2)·W^(-1)at275.8 kPa.

关键词： Thermal interface material Surface modification Thermal conductivity Thixotropy Interface thermal resistance

丝胶抗冻肽在大肠杆菌中的重组表达及其抗冻活性初探

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食品工业科技 2018年第21期39卷 141-145,206页

作者：金泉张莉吴金鸿汪少芸李灵王正武上海交通大学农业与生物学院上海200240 福州大学生物科学与工程学院福建福州350108

为了高效制备抗冻肽,研究一种丝胶抗冻肽目的基因SerD在大肠杆菌BL21菌株中的重组表达,并分析表达产物的抗冻活性。首先合成SerD基因片段,经KpnI和XhoI双酶切后定向插入质粒载体Pet32a中,构建表达质粒Pet32a-SerD,然后电转化入大肠杆菌B... 详细信息

为了高效制备抗冻肽,研究一种丝胶抗冻肽目的基因SerD在大肠杆菌BL21菌株中的重组表达,并分析表达产物的抗冻活性。首先合成SerD基因片段,经KpnI和XhoI双酶切后定向插入质粒载体Pet32a中,构建表达质粒Pet32a-SerD,然后电转化入大肠杆菌BL21(DE3),在IPTG诱导下进行目的基因表达,利用镍琼脂糖亲和层析对目的重组蛋白进行纯化,并对其进行抗冻活性分析。结果表明,最佳表达条件为重组菌在20℃诱导16 h;通过十二烷基硫酸钠聚丙烯酰胺凝胶电泳(Sodium Dodecyl Sulphate-PolyAcrylamide Gel Electrophoresis,SDS-PAGE)和蛋白质免疫印迹试验(Western-Blot)鉴定重组蛋白表达成功且His-SerD融合蛋白表达的分子量在25～35 kDa之间;胞内表达His-SerD融合蛋白的大肠杆菌BL21-SerD复苏后的生长活性明显高于PBL空载菌;添加His-SerD融合蛋白可明显降低溶液中冰晶颗粒大小,具有较好的重结晶抑制效果。本文通过基因工程方法在大肠杆菌中成功构建丝胶肽抗冻肽的重组表达系统,并最终获得具有抗冷冻胁迫保护作用的His-SerD融合蛋白。

关键词：丝胶肽大肠杆菌重组表达抗冻活性

Simulation of RFI Cancellation Using Subspace Projection Algorithm for PAF Receiver

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Research in Astronomy and Astrophysics 2024年第1期24卷 237-244页

作者： Peng wu Jian Li Mao-zheng Chen Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Xinjiang Key Laboratory of Microwave Technology Urumqi 830011China

The simulation of radio frequency interference(RFI) cancellation by applying a spatial filtering technique for phased array feed(PAF) is presented. In order to better reflect the characteristics of PAF, a new signal model is to add the coupling coefficient among elements of PAF to the conventional array signal model. Then the subspace projection(SP) algorithm is used to cancel RFI from the correlation matrix of the signal, and finally, the 2D power image is drawn. The power variation of signal-of-interest direction and RFI direction before and after using the SP algorithm is analyzed. The new signal model and simulation strategy can be used to test and verify the beamformer.

关键词： methods:analytical techniques:radar astronomy telescopes

Optical detection method of discharge mode transition of inductively coupled plasma in an atmosphere-breathing electric propulsion system

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Chinese Journal of Aeronautics 2024年第10期37卷 172-183页

作者： Yuxuan ZHONG Yu ZHANG Jianjun wu Peng zheng College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

Plasma discharge stability is an important problem in atmosphere-breathing electric propulsion system when maintaining long-term missions at ultra-low earth *** paper designed an inductively coupled plasma source to imitate the ionization *** effect of inflow rate and Radio Frequency(RF)power on the plasma discharge mode transition is experimentally studied.A discharge mode detection method is proposed,which determines the discharge mode by identifying the morphology of the plasma *** using the method,the discharge mode transition is quantified and a control model based on the parameter sensitivity is *** verify the method,the spectra are measured and the electron temperature spatial distribution is *** the method has been proven *** results show that the inductively coupled discharge contains capacitive components affected by the mass flow rate and the radio frequency *** plasma characteristics can be maintained stably by controlling the radio frequency power when the mass flow rate randomly changes in a certain *** is demonstrated that the application of detection method effectively identifies the discharge mode,which is a promising active control method for the plasma discharge mode.

关键词： Atmosphere-breathing electric propulsion Inductively coupled plasma Discharge mode transition Optical diagnosis Ultra-low earth orbit

A buffer overflow detection and defense method based on RiSC-V instruction set extension

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Cybersecurity 2024年第2期7卷 28-43页

作者： Chang Liu Yan-Jun wu Jing-zheng wu Chen Zhao Intelligent Software Research Center Institute of SoftwareChinese Academy of SciencesBejingChina University of Chinese Academy of Sciences BeijingChina State Key Laboratory of Computer Science Institute of SoftwareChinese Academy of SciencesBeijingChina

Buffer overflow poses a serious threat to the memory security of modern operating *** overwrites the con-tents of other memory areas by breaking through the buffer capacity limit,destroys the system execution environ-ment,and provides implementation space for various system attacks such as program control flow *** makes it a wide range of harms.A variety of security technologies have been proposed to deal with system security problems including buffer *** example,No eXecute(NX for short)is a memory management technology commonly used in Harvard *** can refuse the execution of code which residing in a specific memory,and can effectively suppress the abnormal impact of buffer overflow on control ***,in recent years,it has also been used in the field of system security,deriving a series of solutions based on NX technology,such as ExecShield,DEP,StackGuard,***,these security solutions often rely too much on the processor archi-tecture so that the protection coverage is insufficient and the accuracy is *** in the emerging system architecture field represented by RiSC-V,there is still a lack of effective solutions for buffer overflow *** the continuous rapid development of the system architecture,it is urgent to develop defense methods that are applicable to different system application environments and oriented to all executable memory spaces to meet the needs of system security ***,we propose BOP,A new system memory security design method based on RISC-V extended instructions,to build a RISC-V buffer overflow detection and defense system and deal with the buffer overflow threat in *** to this method,NX technology can be combined with program control flow analysis,and Nx bit mechanism can be used to manage the executability of memory space,so as to achieve a more granular detection and defense of buffer overflow attacks that may occur in RISC-V system

关键词： RISc-V Operating system security Buffer overflow Control flow hijacking Nx bit Xibop

State estimation for delayed switched positive systems: delayed radius approach

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Science China(Information Sciences) 2024年第8期67卷 190-205页

作者： Weizhong CHEN Zhongyang FEI Xudong ZHAO zheng-Guang wu School of Electronics and Information Xi'an Polytechnic University Research Institute of Intelligent Control and Systems Harbin Institute of Technology Key Laboratory of Intelligent Control and Optimization for Industrial Equipment of Ministry of Education Dalian University of Technology School of Control Science and Engineering Dalian University of Technology State Key Laboratory of Industrial Control Technology Institute of Cyber-Systems and ControlZhejiang University

In this paper, an interval estimation scheme is developed for delayed switched positive systems（DSPS） with mode-dependent average dwell time switching. A lossless zonotopic estimation approach is proposed for the delayed intersection zonotope with the positive generator matrix. First, considering the existence of asynchronism between the system mode and the correction matrix mode, the mismatched intersection zonotope is constructed for DSPS to verify the consistency between the system model and ***, by utilizing the introduced radius definitions, the ?∞performance is addressed to optimize the size of delayed intersection zonotopes. Subsequently, we present a joint-design approach of switching signals and the mode-dependent correction matrix by constructing positive generator matrix-based delayed radius functions. Furthermore, guaranteed nonnegative state bounds are derived for the considered DSPS based on the proposed lossless zonotopic estimation criteria. Finally, detailed simulations are conducted to validate the feasibility and superiority of the developed methods.

关键词： delayed switched positive systems interval estimation asynchronous correction matrix zonotopes mode-dependent average dwell time