检索结果-南通市图书馆

Characteristics of a pre-combustion plasma jet igniter

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第7期37卷 178-189页

作者： Jinlu yu Baowen ZHANG Yang yu Bingbing ZHAO lei ZHANG Aviation Engineering School Air Force Engineering UniversityXi’an 710038China Equipment Management and Unmanned Aerial Vehicle Engineering School Air Force Engineering UniversityXi’an 710038China

Plasma ignition technology has delivered good performance in the aerospace industry. In this study, a pre-combustion plasma jet igniter was designed, and its characteristics were examined from three aspects: the morphology, temperature, and discharge characteristics and process of ignition. Images of the OH distribution were obtained by using an OH Planar Laser-Induced Fluorescence(OH-PLIF) experimental system. Results have shown that the proposed plasma jet had a higher OH concentration, longer length, and larger area than those of a traditional igniter. The stability of discharge of the igniter was improved as the equivalence ratio φ was increased, and reducing gas flow reduced the pulsation of the plasma jet. When the input current was increased from 15A to 35 A, the highest average temperature increased from 5127 K to 7987 K. An increase in the equivalence ratio reduced the region of arc ionization, but expanded the regions of the core combustion reaction and the outer flame. Herein, this study has obtained a deep understanding of the jet and ignition law and developed a new idea for the application of plasma in the ignition field.A pre-combustion plasma jet igniter can significantly improve the efficiency of ignition and shorten the ignition process compared with a traditional igniter.

关键词： Pre-combustion plasma igniter Plasma Jet temperature field Ignition process Arc Flame

Chord length sampling correction analysis for dispersion fuel in Monte Carlo simulation

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第4期35卷 57-64页

作者： Zhao-yu Liang Ding She yu-Tong Wen lei Shi Institute of Nuclear and New Energy Technology(INET) Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China

Dispersion fuels,knowned for their excellent safety performance,are widely used in advanced reactors,such as hightemperature gas-cooled *** with deterministic methods,the Monte Carlo method has more advantages in the geometric modeling of stochastic *** explicit modeling method has high computational accuracy and high computational *** chord length sampling(CLS)method can improve computational efficiency by sampling the chord length during neutron transport using the matrix chord length?s probability density *** study shows that the excluded-volume effect in realistic stochastic media can introduce certain deviations into the CLS.A chord length correction approach is proposed to obtain the chord length correction factor by developing the Particle code based on equivalent transmission *** numerical analysis against reference solutions from explicit modeling in the RMC code,it was demonstrated that CLS with the proposed correction method provides good accuracy for addressing the excludedvolume effect in realistic infinite stochastic media.

关键词： Stochastic media Monte Carlo Chord length sampling Excluded-volume effect Chord length correction

deep kernel extreme learning machine classifier based on the improved sparrow search algorithm

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2024年第3期31卷 15-29页

作者： Zhao Guangyuan lei yu School of Automation Xi'an University of Posts and TelecommunicationsXi'an 710000China

In the classification problem,deep kernel extreme learning machine(DKELM)has the characteristics of efficient processing and superior performance,but its parameters optimization is *** improve the classification accuracy of DKELM,a DKELM algorithm optimized by the improved sparrow search algorithm(ISSA),named as ISSA-DKELM,is proposed in this *** at the parameter selection problem of DKELM,the DKELM classifier is constructed by using the optimal parameters obtained by ISSA *** order to make up for the shortcomings of the basic sparrow search algorithm(SSA),the chaotic transformation is first applied to initialize the sparrow ***,the position of the discoverer sparrow population is dynamically adjusted.A learning operator in the teaching-learning-based algorithm is fused to improve the position update operation of the ***,the Gaussian mutation strategy is added in the later iteration of the algorithm to make the sparrow jump out of local *** experimental results show that the proposed DKELM classifier is feasible and effective,and compared with other classification algorithms,the proposed DKELM algorithm aciheves better test accuracy.

关键词： deep kernel extreme learning machine(DKELM) improved sparrow search algorithm(ISSA) classifier parameters optimization

Molecules for COVID-19 treatment

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第7期35卷 59-65页

作者： Zhigang Zeng Changzhou Liao lei yu Hubei Key Laboratory of Radiation Chemistry and Functional Materials School of Nuclear Technology and Chemistry&BiologyHubei University of Science and TechnologyXianning 437100China Hubei Industry Technology Research Institute of Intelligent Health Xianning 437100China School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China

COVID-19 is a major event with worldwide *** the beginning of the epidemic,pharmaceutical chemists have paid attention to the therapeutic effect of a variety of small molecule medicines on COVID-19 infection.A series of organic molecules are designed and found to be effective in the treatment of COVID-19 *** fact,no matter how effective they are,with the development of the COVID-19 epidemic,various small molecule medicines are gradually recognized by *** is equivalent to a good science popularization of pharmaceutical *** review aims to introduce the molecules for COVID-19 treatment on the basis of their chemical structures,synthetic methods as well as their effects.

关键词： COVID-19 Small molecule medicines "Star"drugs Chemical structure Synthetic method

Power and rate adaption in wireless communication systems with energy harvesting-based on soft decision decoding

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2024年第4期31卷 70-82页

作者： lei Weijia yu Shunhong Liu Meiding School of Communications and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing 400065China Chongqing Key Lab of Mobile Communication Technology Chongqing 400065China

In this paper,the online power control and rate adaptation for a wireless communication system with energy harvesting(EH)are investigated,in which soft decision decoding is adopted by the *** efficiently utilize the harvested energy and maximize the actual achievable transmission rate under the constraints of the available channel codes and modulation schemes,the transmit power,code rate and modulation order are jointly *** Lyapunov framework is used to transform the long-term optimization problem into a per time slot optimization *** there is no theoretical formula for the error rate of soft decision decoding,the optimization problem cannot be solved analytically.A table to find the optimal modulation order and code rate under the different values of signal-to-noise ratio(SNR)is built first,and then a numerical algorithm to find the solution to the optimization problem is *** feasibility and performance of the proposed algorithm are demonstrated by *** simulation results show that compared with the algorithms to maximize the theoretical channel capacity,the proposed algorithm can achieve a higher actual transmission rate.

关键词： energy harvesting power control rate adaption soft decision decoding Lyapunov framework

Reduction of unactivated alkyl chlorides enabled by light-induced single electron transfer

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第2期67卷 471-481页

作者： lei Dai Zhao-Fei Zhang Xiang-yu Chen School of Chemical Sciences University of the Chinese Academy of SciencesBeijing100049China Institute of Chemistry Chinese Academy of SciencesBeijing100190China Binzhou Institute of Technology Weiqiao-UCAS Science and Technology ParkBinzhou256606China

Alkyl chlorides are abundant and easily accessible starting ***,due to the high reduction potentials associated with unactivated alkyl chlorides,achieving their single electron reduction remains a persistent *** challenge has spurred the exploration of efficient activation methods to overcome this *** recent years,photocatalysis has emerged as a mild and potent tool for the single electron reduction of unactivated alkyl chlorides,opening up new possibilities in this *** the rapid advancements in this area,a comprehensive review that provides a conceptual understanding of this emerging field,with a specific focus on reaction design and catalytic mechanisms,would be timely and highly ***,we present an overview of various synthetic techniques for photoinduced single electron reduction of unactivated alkyl ***,we also discuss the limitations of the present methods and future directions that lie ahead in this field.

关键词： photocatalysis unactivated alkyl chlorides single electron transfer radical reactions

Performance analysis and multi-objective optimization based on a modified irreversible Stirling cycle

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第6期67卷 1668-1684页

作者： XU lei yu MinJie LIU ZhiChun LIU Wei School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhan430074China

The efficiency of the actual Stirling engine is much lower than the ideal Carnot cycle *** obtain more precise efficiency for Stirling engines,this paper proposes a modified Stirling cycle with a more accurate heat transfer process in Stirling engines based on a thermodynamic function called available *** finite-time thermodynamic method is used to analyze the model performance under constant heat source temperature,finite temperature difference heat transfer,and incomplete regenerative processes.A new polytropic process is introduced to model the heat transfer between the working fluid and external heat sources in which only heat above ambient temperature is converted into technical *** regenerator is divided into numerous smaller heat reservoirs with individual temperature to analyze the incomplete regenerative *** expressions of the output power and thermal efficiency are obtained based on the modified irreversible Stirling cycle,and the effects of irreversible losses are analyzed to evaluate the performance of the proposed *** indicate that the efficiency of the modified cycle is much lower than that of the ideal Stirling cycle with an isothermal *** the increase of the average heat transfer temperature difference,there exists an optimum value for the power of the irreversible *** optimum power of the model was obtained for varying thermodynamic parameters by optimizing the average heat transfer temperature difference between the hot and cold *** optimize the irreversible model,the multi-objective optimization analysis is carried out based on NSGA-Ⅱ,which results in an optimized output power of 40.87 kW and an optimized thermal efficiency of 44%.

关键词： stirling cycle regenerative processes isopotential processes multi-objective optimization finite time thermodynamics

Experimental observations on the nonproportional multiaxial ratchetting of cast AZ91 magnesium alloy at room temperature

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 1115-1125页

作者： Binghui Hu yu lei Hang Li Ziyi Wang Chao yu Guozheng Kang Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China

The nonproportional multiaxial ratchetting of cast AZ91 magnesium (Mg) alloy was examined by performing a sequence of axial-torsional cyclic tests controlled by stress with various loading paths at room temperature (RT).The evolutionary characteristics and path dependence of multiaxial ratchetting were *** illustrate that the cast AZ91 Mg alloy exhibits considerable nonproportional additional softening during cyclic loading with multiple nonproportional multiaxial loading paths;multiaxial ratchetting presents strong path dependence,and axial ratchetting strains are larger under nonproportional loading paths than under uniaxial and proportional45°linear loading paths;multiaxial ratchetting becomes increasingly pronounced as the applied stress amplitude and axial mean stress ***,stress-strain curves show a convex and symmetrical shape in axial/torsional *** ratchetting exhibits quasi-shakedown after certain loading *** abundant experimental data obtained in this work can be used to develop a cyclic plasticity model of cast Mg alloys.

关键词： cast magnesium alloy ratchetting multiaxial loading loading path stress level

Analysis of Gram-positive bacterial infection in patients following liver transplantation

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2012年第14期125卷 2417-2421页

作者： LI Hong yu de-lei REN lei ZHONG Lin PENG Zhi-hai TENG Mu-jian department of Hepatobiliary Surgery Qianfoshan HospitalAffiliated to Shandong University Jinan Shandong 250014 China Shandong University School of Medicine Jinan Shandong250061 China department of Hepatobiliary Surgery Affiliated First People'sHospital Shanghai Jiao Tong University Shanghai 200080 China

Background Liver transplantation is the most effective treatment for patients with end-stage liver failure, however infection after transplantation is a serious clinical complication. The purpose of this research was to investigate the molecular epidemiology and the influence of multidrug-resistant Gram-positive infection in patients, following liver transplantation, to provide reference for clinical treatment and prevention of Gram-positive bacterial infection. Methods We isolated and detected bacteria from phlegm, throat swabs, urine, wound or wound secretions, blood, and fecal samples from 221 liver transplant patients in our hospital from January 2007 to April 2010. All isolated bacterial strains were identified and tested by minimal inhibitory concentration （MIC） drug-sensitive detection using the BioMerieux ATB bacterial identification instrument and repetitive extragenic palindromic-polymerase chain reaction （REP-PCR） detection of bacterial homology. Risk factors were calculated by multivariate Logistic regression analysis. Results We collected 250 specimens from 221 patients hospitalized following liver transplantation surgery, of which 29 patients developed multiple infections. Sixty-five Gram-positive bacterial strains were isolated from different specimens from 53 infectious patients. We detected 29 multidrug-resistant Gram-positive strains from 29 patients （44.62%）, including 20 Staphylococcus aureus （S. aureus） strains （68.97%） and nine Enterococcus strains （31.03%）. All 20 S. aureus strains were highly resistant to aminoglycosides （gentamicin）, cephalosporins （cefoxitin）, quinolones （ciprofloxacin and levofloxacin）, lincomycins （clindamycin）, penicillin, and erythromycin. The resistance rate reached 100% in some cases. The S. aureus strains were highly sensitive to vancomycin and oxazolidinone （linezolid）, with MIC50 〈2 pg/ml for both. The nine Enterococci strains were also highly resistant to aminoglycosides, quinolones, and penicillins, and highly se

关键词： Gram-positive bacillus,liver transplantation, molecular epidemiology risk factors