检索结果-南通市图书馆

Correlation analysis between underwater noise and Liutex for DTMB4119 propeller

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2022年第4期34卷 585-595页

作者： Lian-jie Yu jian-wei wu De-cheng Wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China wuhan Second Ship Design and Research Institute Wuhan 430205China

Propeller is an important equipment of ocean *** has characteristics of complex geometry and periodic vortex shed,which means high research *** paper takes DTMB419 propeller as the research object.A detailed study is conducted on the wake vortices in non-cavitation state and cavitation *** vortex identification methods are used to compare the vortices capture effects from downstream sections and three-dimensional *** results show that,the third-generation vortex identification technologyΩ_(R)shows obvious *** the same time,FW-H equation is used to predict propeller noise,and the relationship between nonlinear sound source distribution and vortices distribution is *** is found that the distribution of Lighthill tensor is consistent withΩ_(R),which proves the advantages and potential of third-generation vortex identification technology from acoustic perspective.

关键词： Third-generation vortex DTMB4119 propeller cavitation FW-H formulation

Numerical simulations of FPSO with sloshing tanks in a random freak waves

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2022年第3期34卷 491-498页

作者： Yuan Zhuang Guo Wang De-cheng Wan jian-wei wu Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Marine Design and Research Institute of China Shanghai200011China wuhan Second Ship Design and Research Institute Wuhan430205China

This paper presents a potential-viscous coupled method to simulate a floating production storage and offloading(FPSO)with two liquefied natural gas(LNG)sloshing tanks in a random freak *** potential theory uses high-order-spectral(HOS)*** random wave is generated by HOS for 2000 s,and a freak wave is observed around 1830 *** FPSO LNG model was firstly verified in regular waves using HOS-computational fluid dynamics(CFD)coupled method and validated the HOS-CFD coupled method can solve the ship motion coupled with sloshing tanks *** FPSO with LNG tanks are then simulated in the freak wave,showed the coupling effects when the freak wave *** the existence of the sloshing tanks,the amplitude of the roll motion decreases and the period of roll motion *** breaking phenomenon can be observed when the wave crest of the freak wave encounters with the ship.

关键词： Ship motion with sloshing tank high-order-spectral-computational fluid dynamics(HOS-CFD)method naoe-FOAM-SJTU solver freak waves

Preliminary control of the air entrainment in bow wave based on the Liutex force method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2022年第3期34卷 483-490页

作者： Yi-ding Hu jian-wei wu De-cheng Wan Guo Wang Yi-qian Wang Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China wuhan Second Ship Design and Research Institute Wuhan430205China Marine Design and Research Institute of China Shanghai200011China School of Mathematical Science Soochow UniversitySuzhou215006China

Trails induced by air entrainment of bow wave breaking can be observed clearly around an advancing ship,making it prong to be detected and causing reduction in hydrodynamic *** breaking bow wave region,different scale of coherent vortex structures related closely to the air entrainment are *** formation and evolution of bubble clouds can be accounted partly by the swirling vortex flow of the jet *** this work,high-fidelity simulation of the bow wave breaking around a rectangular thin plate is performed with the in-house code BAMR-SJTU.A Liutex force model is constructed to investigate the interaction between the free surface and vortices,and to explore the possibility of alleviating or controlling the air *** study is the first attempt to manipulate vortices corresponding to the air entrainment of the bow wave *** typical vortex structures based on the Liutex vortex identification method and the distribution of the vortex force are *** of the vortex structures and the entrapped bubbles is conducted to illustrate the efficiency of Liutex force model in air entrainment control.

关键词： Bow wave breaking air entrainment coherent vortex structures Liutex force field model

Adaptive sampling algorithm for detection of superpoints

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 in China(Series F) 2008年第11期51卷 1804-1821页

作者： CHENG Guang GONG jian DING wei wu Hua QIANG ShiQiang Key Lab of jiangsu Computer Network School of Computer Science and Engineering Southeast University Nanjing 210096 China

The superpoints are the sources （or the destinations） that connect with a great deal of destinations （or sources） during a measurement time interval, so detecting the superpoints in real time is very important to network security and management. Previous algorithms are not able to control the usage of the memory and to deliver the desired accuracy, so it is hard to detect the superpoints on a high speed link in real time. In this paper, we propose an adaptive sampling algorithm to detect the superpoints in real time, which uses a flow sample and hold module to reduce the detection of the non-superpoints and to improve the measurement accuracy of the superpoints. We also design a data stream structure to maintain the flow records, which compensates for the flow Hash collisions statistically. An adaptive process based on different sampling probabilities is used to maintain the recorded IP addresses in the limited memory. This algorithm is compared with the other algorithms by analyzing the real network trace data. Experiment results and mathematic analysis show that this algorithm has the advantages of both the limited memory requirement and high measurement accuracy.

关键词： superpoints detection adaptive process flow sample and hold collision compensation

Estimating index of population trend by re-sampling techniques （jackknife and bootstrap） and its application to the life table study of rice leaf roller, Cnaphalocrocis medinalis （Lepidoptera： Pyralidae）

在线全文

学校读者我要写书评

暂无评论

Insect Science 2008年第2期15卷 153-161页

作者： Fang-Ling Tao Shi-Fan Min wei-jian wu Guang-Wen Liang Ling Zeng Laboratory of Insect Ecology South China Agriculture University Guangzhou Department of Food Science Jiangxi AgriculturalUniversity Nanchang China

Taking a published natural population life table of rice leaf roller, Cnaphalocrocis medinalis （Lepidoptera： Pyralidae）, as an example, we estimated the population trend index, I, via re-sampling methods （jackknife and bootstrap）, determined its statistical properties and illustrated the application of these methods in determining the control effectiveness of bio- agents and chemical insecticides. Depending on the simulation outputs, the smoothed distribution pattern of the estimates of I by delete-1 jackknife is visually distinguishable from the normal density, but the smoothed pattern produced by delete-d jackknife, and logarithm- transformed smoothed patterns produced by both empirical and parametric bootstraps, matched well the corresponding normal density. Thus, the estimates of I produced by delete-1 jackknife were not used to determine the suppressive effect of wasps and insecticides. The 95% percent confidence intervals or the narrowest 95 percentiles and Z-test criterion were employed to compare the effectiveness of Trichogrammajaponicum Ashmead and insecticides （powder, 1.5% mevinphos ＋ 3% alpha-hexachloro cyclohexane） against the rice leaf roller based on the estimates of I produced by delete-d jackknife and bootstrap techniques. At a = 0.05 level, there were statistical differences between wasp treatment and control, and between wasp and insecticide treatments, if the normality is ensured, or by the narrowest 95 percentiles. However, there is still no difference between insecticide treatment and control. By Z-test criterion, wasp treatment is better than control and insecticide treatment with P-value 〈 0.01. Insecticide treatment is similar to control with P-value 〉 0.2 indicating that 95% confidence intervals procedure is more conservative. Although similar conclusions may be drawn by re-sampling techniques, such as the delta method, about the suppressive effect of trichogramma and insecticides, the normality of the estimates can be checked and guarante

关键词： index of population trend life table re-sampling (jackknife bootstrap) riceleaf roller ( Cnaphalocrocis medinalis)

Analysis on degradation mechanisms of normally-off p-GaN gate AlGaN/GaN high-electron mobility transistor

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第4期30卷 448-452页

作者： Si-De Song Su-Zhen wu Guo-Zhu Liu wei Zhao Yin-Quan Wang jian-wei wu Qi He The 58th Institution of Electronic Science and Technology Group Corporation of China Wuxi 214000China

The degradation mechanisms of enhancement-mode p-GaN gate AlGaN/GaN high-electron mobility transistor was analyzed extensively,by means of drain voltage stress and gate bias *** results indicate that:(ⅰ) High constant drain voltage stress has only a negligible impact on the device electrical parameters,with a slightly first increase and then decrease in output current;(ⅱ) A negative shift of threshold voltage and increased output current were observed in the device subjected to forward gate bias stress,which is mainly ascribed to the hole-trapping induced by high electric field across the p-GaN/AlGaN interface;(ⅲ) The analyzed device showed an excellent behavior at reverse gate bias stress,with almost unaltered threshold voltage,output current,and gate leakage current,exhibiting a large gate swing in the negative *** results are meaningful and valuable in directing the process optimization towards a high voltage and high reliable enhanced AlGaN/GaN high-electron mobility transistor.

关键词： high-electron-mobility transistors(HEMTs) stress degradation threshold voltage

Optimization of hepatobiliary phase delay time of Gd-EOB-DTPA-enhanced magnetic resonance imaging for identification of hepatocellular carcinoma in patients with cirrhosis of different degrees of severity

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2018年第3期24卷 415-423页

作者： jian-wei wu Yue-Cheng Yu Xian-Li Qu Yan Zhang Hong Gao Department of Radiology Bayi HospitalNanjing University of Chinese Medicine Liver Disease Center Bayi HospitalNanjing University of Chinese Medicine

AIM To optimize the hepatobiliary phase delay time(HBPDT) of Gd-EOB-DTPA-enhanced magnetic resonance imaging(GED-MRI) for more efficient identification of hepatocellular carcinoma(HCC) occurring in different degrees of cirrhosis assessed by Child-Pugh(CP) *** The liver parenchyma signal intensity(LPSI), the liver parenchyma(LP)/HCC signal ratios, and the visibility of HCC at HBP-DT of 5, 10, 15, 20, and 25 min(i.e., DT-5, DT-10, DT-15, DT-20, and DT-25) after injection of GdEOB-DTPA were collected and analyzed in 73 patients with cirrhosis of different degrees of severity(including 42 patients suffering from HCC) and 18 healthy adult *** The LPSI increased with HBP-DT more significantly in the healthy group than in the cirrhosis group(F = 17.361, P < 0.001). The LP/HCC signal ratios had a significant difference(F = 12.453, P < 0.001) among various HBP-DT points, as well as between CP-A and CP-B/C subgroups(F = 9.761, P < 0.001). The constituent ratios of HCC foci identified as obvious hypointensity(+++), moderate hypointensity(++), and mild hypointensity or isointensity(+/-) kept stable from DT-10 to DT-25: 90.6%, 9.4%, and 0.0% in the CP-A subgroup; 50.0%, 50.0%, and 0.0% in the CP-B subgroup; and 0.0%, 0.0%, and 100.0% in the CP-C subgroup, *** The severity of liver cirrhosis has significant negative influence on the HCC visualization by GED-MRI. DT-10 is more efficient and practical than other HBP-DT points to identify most of HCC foci emerging in CP-A cirrhosis, as well as in CP-B cirrhosis; but an HBP-DT of 15 min or longer seems more appropriate than DT-10 for visualization of HCC in patients with CP-C cirrhosis.

关键词： Magnetic resonance imaging Gd-EOBDTPA Hepatobiliary phase Delay time Hepatocellular carcinoma Cirrhosis Optimization

Synthesis of unnatural N-glycosyl α-amino acids via Petasis reaction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2014年第4期25卷 532-534页

作者： Chuan-Zhou Tao Zhong-Tang Zhang jian-wei wu Rong-Hua Li Zhi-Ling Cao School of Chemical Engineering Huaihai Institute of Technology jiangsu Marine Resources Development Research Institute

A convenient and efficient protocol for the synthesis of unnatural N-glycosyl cz-amino acids was developed. Condensation of 1,3,4,6-tetra-O-actyl-/%D-glucosamine hydrochloride, alkenyl boronic acid, and glyoxylic acid was achieved in CH2C12 to give the derivatives of 2-（N-glycosyl）aminobut-3-enoic acid which may find applications in glycobiology research and medicinal chemistry.

关键词： N-'Glycosyl s-amino acid Petasis reaction D-Glucosamine Alkenyl boronic acid

Role of Kasai procedure in surgery of hilar bile duct strictures

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2011年第37期17卷 4231-4234页

作者： Jin-Bo Gao Li-Shan Bai Zhi-jian Hu Jun-wei wu Xin-Qun Chai Department of Hepatobiliary Surgery Union Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan 430022 Hubei Province China

AIM:To assess the application of the Kasai procedure in the surgical management of hilar bile duct ***:Ten consecutive patients between 2005 and 2011 with hilar bile duct strictures who underwent the Kasai procedure were retrospectively *** portoenterostomy with the placement of biliary stents was performed in all *** characteristics,postoperative complications,and long-term outcomes were *** patients were followed up for 2-60 mo ***:Patients were classified according to the Bismuth classification of biliary *** were two Bismuth Ⅲ and eight Bismuth Ⅳ *** lesions were benign and four were *** the benign lesions,three were due to post-cholecystectomy injury,one to trauma,one to inflammation,and one to inflammatory *** the malignant lesions,four were due to hilar *** patients underwent Kasai portoenterostomy with the placement of biliary *** were no perioperative *** patient experienced anastomotic leak and was managed *** other complications occurred *** the follow-up period,all patients reported a good quality of ***:The Kasai procedure combined with biliary stents may be appropriate for patients with hilar biliary stricture that cannot be managed by standard surgical methods.

关键词： Kasai procedure Hilar bile duct Stricture Surgery