检索结果-南通市图书馆

Measurements of non-equilibrium and equilibrium temperature behind a strong shock wave in simulated martian atmosphere

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2012年第5期28卷 1296-1302页

作者： xin Lin Xi-Long yu Fei Li Shao-Hua zhang Jian-Guo xin xin-yu zhang School of Optoelectronics Beijing Institute of Technology State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of Sciences

Non-equilibrium radiation measurements behind strong shock wave for simulated Martian atmosphere are presented in this paper. The shock wave is established in a hydrogen oxygen combustion driven shock tube. Time- resolved spectra of the Av = 0 sequence of the B^2∑^＋ → X^2∑^＋ electronic transition of CN have been observed through optical emission spectroscopy （OES）. A new method, which is based on fitting high resolution spectrum for rotational and vibrational temperatures measurement, is proposed to diag- nose temperature distribution behind the shock wave. It is estimated that the current scheme has the maximum deviation less than 8% （lσ） for vibrational temperature measurement through detailed analysis of the influence of the uncertainties of spectroscopic constants and spectral resolution. Radiation structure of the shock layer, including induction, relaxation and equilibrium process, and corresponding rotational and vibrational temperatures are obtained through time gating OES diagnostics with sub-microsecond temporal resolution. The present extensive results will strongly benefit the reaction rate estimation and computational fluid dynamics （CFD） code validation in high enthalpy Mars reentry chemistry.

关键词： Radiation measurements - Shock wave Marsre-entry Rotational temperature Vibrational temperature

Study on the Improvement Strategies of Physical Environment for Square in Severe Cold Regions' Rural Areas

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2014年第4期21卷 18-23页

作者： xin-yu zhang Hong Jin School of Architecture Harbin Institute of Technology School of Architecture Harbin Institute of Technology

To improve the comfortable physical environment for square in severe cold regions' rural areas. This paper applies the methods of questionnaires,field testing and statistical analysis to compare and analyze two different square cases of Qingyunpu in Liaoning Province,and conclude the main factors which affect the physical environmental comfort. The improvement strategies for physical environment of rural square are put forward from the aspects of site selection,road position,orientation,landscape design,and ground pavement material selection,aiming to provide the design basis for the physical environment of square in severe cold regions' rural areas.

关键词： rural areas of severe cold regions squares physical environment improvement strategies

RF design optimization for the SHINE 3.9 GHz cavity

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2020年第7期31卷 97-105页

作者： yu-xin zhang Jin-Fang Chen Dong Wang Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204China ShanghaiTech University Shanghai 201210China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201204China

The Shanghai high-repetition-rate XFEL and extreme light facility(SHINE)under construction is designed to be one of the most advanced free electron laser(FEL)facilities in the *** main part of the SHINE facility is an 8 GeV superconducting Linac operating in continuous wave(CW)*** Linac consists of seventy-five 1.3 GHz and two 3.9 GHz *** on the design and experience of 3.9 GHz cavities in the European X-ray free electron laser(E-XFEL)and the Linac coherent light source-II(LCLS-II)projects,we optimize the SHINE 3.9 GHz cavity design to adapt it for CW mode *** this paper,we present a particular redesign of the end group for the SHINE 3.9 GHz superconducting cavity that includes a redesign of the end cell and beam pipe to shift away the potentially troublesome lowest highorder modes(HOMs),a modification of the main coupler antenna,and a tuning of the HOM notch filter to meet the cavity *** losses calculations on the HOM coupler antennas show that the overheating on the inner conductor at the operating mode is diminished ***,we have also studied the HOMs to ensure there are no dangerously trapped modes in the optimized cavity design.

关键词： cavity antenna tuning

Numerical investigation of the ship propeller load under reversed propulsion condition

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2021年第2期33卷 361-369页

作者： Xiang Fan Jin-jing Tang yu-xin zhang Hai-su Sun Yi-qing Gu Jing-xin zhang Shanghai Merchant Ship Design and Research Institute Shanghai 201203China Key Laboratory of Hydrodynamics(Ministry of Education) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Stopping maneuver is an important research topic in ship *** stopping ability of ship is not only related to the hydrodynamic characteristics of hull,rudder and propeller,but also related to the capacity of main ***,there are few researches on the capacity of main engine under reversed propulsion *** the paper,a numerical water tank is established to simulate the propeller loads using the computational fluid dynamics(CFD)software STAR CCM+.The numerical model is firstly validated by experimental data,and then is used to investigate the propeller loads on a full-scale model with different ship speed and propeller *** dimensionless,the relations between the advance coefficient and the load coefficients are shown as J-KT curves and J-KQ ***,the flow structures near the propeller and the pressure on the propeller with different J values are *** simulations reveal that the flow velocities induced by the reversed propulsion of the propeller is similar to the wake flow by ship with J=-*** is the reason for the minimum points of J-KT and J-KQ curve occurring in cases with J=-***,the capacity of the main engine and the output load of the propeller are considered *** relations between the ship speeds and the maximum output loads on the propeller are discussed in details.

关键词： Propeller load reverse propulsion computational fluid dynamics(CFD)simulation

Least Squares Model Averaging Based on Generalized Cross Validation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2021年第3期37卷 495-509页

作者： xin-min LI Guo-hua ZOU xin-yu zhang Shang-wei ZHAO School of Mathematics and Statistics Qingdao UniversityQingdao 266071China School of Mathematical Sciences Capital Normal UniversityBeijing 100048China Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China Beijing Academy of Artificial Intelligence Beijing 100084China College of Science Minzu University of ChinaBeijing 100081China

Frequentist model averaging has received much attention from econometricians and statisticians in recent years.A key problem with frequentist model average estimators is the choice of *** paper develops a new approach of choosing weights based on an approximation of generalized cross *** resultant least squares model average estimators are proved to be asymptotically optimal in the sense of achieving the lowest possible squared ***,the optimality is built under both discrete and continuous weigh *** with the existing approach based on Mallows criterion,the conditions required for the asymptotic optimality of the proposed method are more *** studies and real data application show good performance of the proposed estimators.

关键词： asymptotic optimality frequentist model averaging generalized cross validation mallows criterion

Optical coherence tomography evaluation of retinal nerve fiber layer thickness in non-arteritic anterior ischemic optic neuropathy and primary open angle glaucoma:a systematic review and Meta-analysis

在线全文

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2022年第8期15卷 1370-1380页

作者： yu-xin Tong xin-yu zhang Yi He Zong-Lin Chen Bing Jiang Department of Ophthalmology Second Xiangya HospitalCentral South UniversityChangsha 410011Hunan ProvinceChina Hunan Clinical Research Center of Ophthalmic Disease Changsha 410011Hunan ProvinceChina Department of Neurosurgery Xiangya HospitalCentral South UniversityChangsha 410008Hunan ProvinceChina Department of General Surgery Second Xiangya HospitalCentral South UniversityChangsha 410011Hunan ProvinceChina

AIM:To assess the differences in average and sectoral peripapillary retinal nerve fiber layer(p RNFL)thickness using spectral domain optical coherence tomography(SD-OCT)in patients with non-arteritic anterior ischemic neuropathy(NAION)compared with those with primary open angle glaucoma(POAG).METHODS:A comprehensive literature search of the Pub Med,Cochrane Library,and Embase databases were performed prior to October,*** that compared the p RNFL thickness in NAION eyes with that in POAG eyes with matched mean deviation of the visual fields were *** weighted mean difference(WMD)with 95%confidence interval(CI)was used to pool continuous ***:Ten cross-sectional studies(11 datasets)comprising a total of 625 eyes(278 NAION eyes,347 POAG eyes)were included in the qualitative and quantitative *** pooled results demonstrated that the superior p RNFL was significantly thinner in NAION eyes than in POAG eyes(WMD=-6.40,95%CI:-12.22 to-0.58,P=0.031),whereas the inferior p RNFL was significant thinner in POAG eyes than in NAION eyes(WMD=11.10,95%CI:7.06 to 15.14,P≤0.001).No difference was noted concerning the average,nasal,and temporal p RNFL thickness(average:WMD=1.45,95%CI:-0.75 to 3.66,P=0.196;nasal:WMD=-2.12,95%CI:-4.43 to 0.19,P=0.072;temporal:WMD=-1.24,95%CI:-3.96 to 1.47,P=0.370).CONCLUSION:SD-OCT based evaluation of inferior and superior p RNFL thickness can be potentially utilized to differentiate NAION from POAG,and help to understand the different pathophysiological mechanisms between these two *** longitudinal studies and studies using eight-quadrant or clock-hour classification method are required to validate the obtained findings.

关键词： non-arteritic anterior ischemic optic neuropathy primar y open angle glaucoma optical coherence tomography peripapillary retinal nerve fiber layer thickness

Numerical simulation and method study of X-ray litho-density logging

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2020年第12期31卷 129-138页

作者： Hua-Wei yu yu-xin zhang Xiang-Hong Chen Wen-Ding Wang Chao-Zhuo Liu Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580China School of Geosciences China University of Petroleum(East China)Qingdao 266580China College of Science China University of Petroleum(East China)Qingdao 266580China

To effectively replace the isotope radiation source in litho-density logging,this study presents a method for measuring the formation density and photoelectric absorption index(Pe)using a switchable X-ray ***,the gamma-ray litho-density logging(GLD)method for measuring formation density and Pe using chemical sources is ***,a benchmark verification based on the X-ray litho-density logging tool prototype and data published by Simon(In:Paper presented at the SPWLA 59th annual logging symposium,London,UK,2018)was carried out using Monte Carlo numerical ***,the impacts of the photoelectric effect and detector statistical error on the GLD method were ***,based on a theoretical analysis,the formation density and Pe measurement algorithm(double energy window(DEW)method)was improved,which was found to be suitable for X-ray litho-density ***,the results obtained using this algorithm were compared with those obtained using the GLD *** results indicate that owing to the impact of photoelectric effect and detector statistical error on the density energy window,the accuracy of formation density and Pe measurement using the GLD method is relatively low,with the uncertainty in formation density and Pe measurement reaching 2.620±0.047 g/cm3 and 4.090±0.580 b/e,*** comparison,the DEW method can improve the accuracy of density and Pe measurement to 0.006 g/cm3 and 0.065 b/e,respectively,as the photoelectric effect in the density window is corrected using the counts in the lithology window of the energy *** study aims to provide a new theoretical foundation for processing X-ray litho-density logs in the future.

关键词： X-ray controllable source Litho-density logging Monte Carlo simulation

Speech Suppression with EEMD_WP

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2013年第1期20卷 123-128页

作者： xin-yu zhang Xue-Yao Li Ru-Bo zhang College of Computer Science and Technology Harbin Engineering University School of Management Harbin University of Commerce

In non-cooperation communication, speech suppression is an important link of aircraft type recognition based on shortwave speech communication. Ensemble mean and ensemble variance for analyzing physical characteristics of aircraft cockpit background sound has been proposed in this paper. Some important peak feature is revealed from the ensemble mean and ensemble variance, which has important guiding significance to further researches on speech suppression of aircraft type recognition based on shortwave speech communication. The two algorithms of speech suppression are proposed which are empirical mode decomposition and wavelet transform(EMD_WT) and the algorithm of ensemble empirical mode decomposition and wavelet packet (EEMD_WP). In the process of speech suppression, EMD_WT produced extra noise pollution, and EEMD_WP kept the aircraft cockpit background sound and weakened the effect of the speech largely. The contrast test proves that EEMD_WP has better performance by in time domain and in frequency domain.

关键词： speech suppression ensemble mean wavelet packet shortwave communication

Effects of a combined infection with Paranosema locustae and Beauveria bassiana on Locusta migratoria and its gut microflora

在线全文

学校读者我要写书评

暂无评论

Insect Science 2021年第2期28卷 347-354页

作者： Shu-Qian Tan yue Yin Kai-Li Cao xin-xin Zhao Xiao-yu Wang yu-xin zhang Wang-Peng Shi Department of Entomology and MO A Key Lab of Pest Monitoring and Green Management College of Plant ProtectionChina Agricultural UniversityBeijingChina Institution of Plant Protection Academy of Ningxia Agricultural and Forestry ScienceYinchuanChina

Even though Paranosema locustae is widely used in China as a biological agent for controlling grasshoppers,the mortality rate is initially quite *** study sought to determine whether the simultaneous use of *** and Beauveria bassiana would be a more effective control ***,changes in the intestinal microbial communities of migratory locusts infected with the two pathogens were analyzed to investigate the roles of gut microbes in pathogen-host *** mortality rate of locusts inoculated with *** and *** simultaneously was not significantly higher than expected but the mortality rates of locusts inoculated with *** 3,6,and 9 days after inoculation with *** were significantly higher than if their effects were additive,indicating synergism.A MiSeq analysis found that Weissella was the most common bacterium,representing 41.48%and 51.62%of the total bacteria in the mid-and hindguts,respectively,and the bacterial declines were greatest during dual infections with *** and *** appropriately timed combined application of *** and *** was more effective against locusts than either treatment ***,the combined inoculation of the two pathogens changed the gut microflora of locusts,indicating the potential relevancy of their synergistic effects on locust control.

关键词： entomopathogenic fungi intestinal symbiotic bacteria microsporidia migratory locust