检索结果-南通市图书馆

Effect of impeller reflux balance holes on pressure and axial force of centrifugal pump

Journal of Central South University 2015年第5期22卷 1695-1706页

作者：曹卫东代珣胡啟祥 Technical and research center of Fluid Machinery engineering Jiangsu University

The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low specific-speed centrifugal pump with Q=12.5 m3/h, H=60 m, n=2950 r/min was selected to be designed with eight axial reflux balance holes with 4.5 mm in diameter. The simulated Q-H curve and net positive suction head(NPSH) were in good agreement with experimental results, which illustrated that centrifugal pump with axial reflux balance holes was superior in the cavitation characteristic; however, it showed to little superiority in head and efficiency. The pressure in rear pump chamber at 0.6 times rate flow is 29.36% of pressure difference between outlet and inlet, which reduces to 29.10% at rate flow and 28.33% at 1.4 times rate flow. As the whole, the pressure distribution on front and rear shrouds from simulation results is not a standard parabola, and axial force decreases as flow rate increases. Radical reflux balance holes chosen to be 5.2 mm and 5.9 mm in diameter were further designed with other hydraulic parts unchanged. With structural grids adopted for total flow field, contrast numerical simulation on internal flow characteristics was conducted based on momentum equations and standard turbulence model(κ-ε). It is found that axial force of pump with radical reflux balance holes of5.2 mm and 5.9 mm in diameter is significantly less than that with radical reflux balance holes of 4.5 mm in diameter. Better axial force balance is obtained as the ratio of area of reflux balance holes and area of sealing ring exceeds 6.

关键词： centrifugal pump low specific-speed radical reflux balance holes numerical simulation pressure gradient axial force

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Experimental investigation and numerical analysis of unsteady attached sheetcavitating flows in a centrifugal pump

引用

Journal of Hydrodynamics 2013年第3期25卷 370-378页

作者：刘厚林刘东喜王勇吴贤芳王健杜辉 research center of Fluid Machinery engineering and Technology Jiangsu University

This paper studies the attached sheet cavitation in centrifugal pumps. A pump casted from Perspex is used as the test subject. The cavitation bubbles were observed in the entrance of the impeller and the drops of the head coefficients were measured under different operating conditions. A Filter-Based Model （FBM）, derived from the RNG k-e model, and a modified Zwart model are adopted in the numerical predictions of the unsteady cavitating flows in the pump. The simulations are carded out and the results are compared with experimental results for 3 different flow coefficients, from 0.077 to 0.114. Under four operating conditions, qualitative comparisons are made between experimental and numerical cavitation patterns, as visualized by a high-speed camera and described as isosurfaces of the vapour volume fraction ctv = 0.1. It is shown that the simulation can truly represent the development of the attached sheet cavitation in the impeller. At the same time, the curves for the drops of the head coefficients obtained from experiments and calculations are also quantitatively compared, which shows that the decline of the head coefficients at every flow coefficient is correctly captured, and the prediction accuracy is high. In addition, the detailed analysis is made on the vapour volume fraction contours on the plane of span is 0.5 and the loading distributions around the blade section at the midspan. It is shown that the FBM model and the modified Zwart model are effective for the numerical simulation of the cavitating flow in centrifugal pumps. The analysis results can also be used as the basis for the further research of the attached sheet cavitation and the improvement of centrifugal pumps.

关键词： centrifugal pump attached sheet cavitation high-speed camera modified Zwart model Filter-Based Mode (FBM)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Prediction of sepsis within 24 hours at the triage stage in emergency departments using machine learning

引用

World Journal of Emergency Medicine 2024年第5期15卷 379-385页

作者： Jingyuan Xie Jiandong Gao Mutian Yang Ting Zhang Yecheng Liu Yutong Chen Zetong Liu Qimin Mei Zhimao Li Huadong Zhu Ji Wu Department of Electronic engineering Tsinghua UniversityBeijing 100084China center for Big Data and Clinical research Institute for Precision MedicineTsinghua UniversityBeijing 100084China Institute of Medical Technology Peking University Health Science CenterBeijing 100091China Emergency Department State Key Laboratory of Complex Severe and Rare DiseasesPeking Union Medical College HospitalChinese Academy of Medical Science and Peking Union Medical CollegeBeijing 100005China Department of Health Care Peking Union Medical College HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100005China

BACKGROUND:Sepsis is one of the main causes of mortality in intensive care units(ICUs).Early prediction is critical for reducing *** approximately 36%of sepsis occur within 24 h after emergency department(ED)admission in Medical Information Mart for Intensive Care(MIMIC-IV),a prediction system for the ED triage stage would be *** methods such as the quick Sequential Organ Failure Assessment(qSOFA)are more suitable for screening than for prediction in the ED,and we aimed to fi nd a light-weight,convenient prediction method through machine ***:We accessed the MIMIC-IV for sepsis patient data in the *** dataset comprised demographic information,vital signs,and synthetic *** Gradient Boosting(XGBoost)was used to predict the risk of developing sepsis within 24 h after ED ***,SHapley Additive exPlanations(SHAP)was employed to provide a comprehensive interpretation of the model's *** percent of the patients were randomly selected as the testing set,while the remaining patients were used for training with 10-fold ***:For 10-fold cross-validation on 14,957 samples,we reached an accuracy of 84.1%±0.3%and an area under the receiver operating characteristic(ROC)curve of 0.92±*** model achieved similar performance on the testing set of 1,662 *** values showed that the fi ve most important features were acuity,arrival transportation,age,shock index,and respiratory ***:Machine learning models such as XGBoost may be used for sepsis prediction using only a small amount of data conveniently collected in the ED triage *** may help reduce workload in the ED and warn medical workers against the risk of sepsis in advance.

关键词： Sepsis Machine learning Emergency department Triage Informatics

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Rice Storage Proteins:Focus on Composition,Distribution,Genetic Improvement and Effects on Rice Quality

引用

Rice science 2023年第3期30卷 207-221,I0035-I0037页

作者： LONG Xinkang GUAN Chunmin WANG Lin JIA Liting FU Xiangjin LIN Qinlu HUANG Zhengyu LIU Chun national engineering research center for Rice and By-Product Deep Processing/School of Food Science and engineering Central South University of Forestry and TechnologyChangsha 410004China

Rice storage proteins(RSPs)are plant proteins with high nutritional *** the second largest type of storage substance in rice,it is the main source of protein intake for people who consume rice as a staple *** content and type of RSPs affect the appearance,processing quality and eating quality of *** effects involve the distribution of RSPs in rice grains as well as the interactions of RSPs with other components such as starch in rice *** the past two decades,some progress has been made in the genetic improvement of ***,the determination mechanism of protein content and composition in rice is still unclear,and the mechanism of the effect of RSPs on rice quality has not been *** this review,the composition,biosynthesis and distribution of RSPs,and quantitative trait loci mapping and cloning of RSP genes are summarized,the research progress of the influence of RSPs and their components on rice quality are reviewed,and the research directions in the future are proposed.

关键词： rice storage protein composition distribution genetic improvement rice quality

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Suppression of Fusarium Wilt of Banana with Application of Bio-Organic Fertilizers

引用

Pedosphere 2014年第5期24卷 613-624页

作者： ZHANG Nan HE Xin ZHANG Juan W.RAZA YANG Xing-Ming RUAN Yun-Ze SHEN Qi-Rong HUANG Qi-Wei national engineering research center for Organic-Based Fertilizers Nanjing Agricultural University Shandong Product Quality Inspection research Institute College of Agronomy Hainan University

Fusarium wilt is one of the most serious diseases of banana plants caused by soil-borne pathogen Fusarium oxysporum ***. cubense(FOC). In this study a pot experiment was conducted to evaluate the effects of different bio-organic fertilizers(BIOs) on Fusarium wilt of banana, including the investigations of disease incidence, chitinase and β-1,3-glucanase activities of banana plants, and FOC populations as well as soil rhizosphere microbial community. Five fertilization treatments were considered, including chemical fertilizer containing the same N, P and K concentrations as the BIO(control), and matured compost mixed with antagonists Paenibacillus polymyxa SQR-21 and Trichoderma harzianum T37(BIO1), Bacillus amyloliquefaciens N6(BIO2), Bacillus subtilis N11(BIO3), and the combination of N6 and N11(BIO4). The results indicated that the application of BIOs significantly decreased the incidence rate of Fusarium wilt by up to 80% compared with the control. BIOs also significantly promoted plant growth, and increased chitinase andβ-1,3-glucanase activities by 55%–65% and 17.3%–120.1%, respectively, in the banana roots. The population of FOC in the rhizosphere soil was decreased significantly to about 104 colony forming units g-1with treatment of BIOs. Serial dilution plating and denaturing gradient gel electrophoresis analysis revealed that the application of BIOs increased the densities of bacteria and actinomycetes but decreased the number of fungi in the rhizosphere soil. In general, the application of BIOs revealed a great potential for the control of Fusarium wilt disease of banana plants.

关键词： biocontrol denaturing gradient gel electrophoresis fungal disease manure compost

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Numerical and experimental studies of hydraulic noise induced by surface dipole sources in a centrifugal pump

引用

Journal of Hydrodynamics 2016年第1期28卷 43-51页

作者：刘厚林戴菡葳丁剑谈明高王勇黄浩钦 research center of Fluid Machinery engineering and Technology Jiangsu University

The influences of the four different surface dipole sources in a centrifugal pump on the acoustic calculating accuracy are studied in this paper, by using the CFD combined with the Lighthill acoustic analogy methods. Firstly, the unsteady flow in the pump is solved based on the large eddy simulation method and the pressure pulsations on the four different surfaces are obtained. The four surfaces include the volute surface, the discharge pipe surface, the inner surface of the pump cavity, and the interfaces between the impeller and the stationary parts as well as the outer surface of the impeller. Then, the software Sysnoise is employed to interpolate the pressure fluctuations onto the corresponding surfaces of the acoustic model. The Fast Fourier Transform with a Hanning window is used to analyze the pressure fluctuations and transform them into the surface dipole sources. The direct boundary element method is applied to calculate the noise radiated from the dipole sources. And the predicted sound pressure level is compared with the experimental data. The results show that the pressure fluctuations on the discharge pipe surface and the outer surface of the impeller have little effect on the acoustic simulation results. The pressure pulsations on the inner surface of the pump cavity play an important role in the internal flow and the acoustic simulation. The acoustic calculating error can be reduced by about 7% through considering the effect of the pump cavity. The sound pressure distributions show that the sound pressure level increases with the growing flow rate, with the largest magnitude at the tongue zone.

关键词： centrifugal pump noise large eddy simulation(LES) dipole source experiment

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Novel approaches to produce Al2O3-TiC/TiCN-Fe composite powders directly from ilmenite

引用

Progress in Natural Science:Materials International 2013年第5期23卷 501-507页

作者： Aitao Tang Shengming Liu Fusheng Pan College of Materials Science and engineering Chongqing University Chongqing Academy of Science&Technology national engineering research center for Magnesium Alloys

Al2O3 –TiC/TiCN–Fe composite powders were successfully prepared directly from ilmenite at 1300–1400℃.The effects of Al/C ratio,sintering atmosphere,and reaction temperature and time on the reaction products were *** showed that the nitrogen atmosphere was bene cial to the reduction of ilmenite and the formation of Al2O3 –TiC/TiCN–Fe composite *** the reaction temperature was between 600 and 1100℃,the intermediate products,TiO2,Ti3O5 and Ti4O7 were found,which changed to TiC or TiCN at higher ***/C ratio was found to affect the reaction process and synthesis *** Al addition was 0.5 mol,the Al2O3 phase did not *** content of carbon in TiCN rose when the reaction temperature was increased.

关键词： Ilmenite Al2O3,TiC,TiCN Composite powder Composite materials

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Self-assembly process of organic small molecular gel and its molecular mechanism

引用

Particuology 2023年第1期72卷 122-133页

作者： Yingjie Ma Na Wang Xin Huang Ting Wang Lina Zhou Xin Li Xiongtao Ji Yihan Zhao Hongxun Hao national engineering research center of Industrial Crystallization Technology School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China Collaborative Innovation center of Chemical Science and engineering(Tianjin) Tianjin 300072China School of Chemical engineering and Technology Hainan UniversityHaikou 570228China

Gel is a very diverse system that has pervaded our everyday life in a variety of forms. However, the mechanism of gel formation remains ambiguous. To better understand the mechanism of gel formation, cefpiramide was selected as model compound to investigate gel formation from molecular level, with the help of experimental research and molecular dynamics simulations. Dynamic light scattering was used to detect the process of the formation of fiber aggregates by the molecules in the gel process. The results indicated that in the process of low molecular weight gels, the molecules coalesce to form a fibrous network structure to wrap the liquid. Attenuated Total Reflectance Fourier Transform Infrared spectrometer and Raman spectroscopy were employed to explore the solute–solute and solute–solvent interactions, which indicated that the solvent molecules (formamide molecules) played a key role in the process of gel formation and the solute–solute interactions played a leading role. Finally, molecular dynamics simulations were employed to reveal the molecular mechanism of gel formation from molecular level.

关键词： Cefpiramide Gel Self-assembly process Molecular interaction

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Numerical and Experimental Study on Flow-induced Noise at Blade-passing Frequency in Centrifugal Pumps

引用

Chinese Journal of Mechanical engineering 2014年第3期27卷 606-614页

作者： YANG Jun YUAN Shouqi YUAN Jianping SI Qiaorui PEI Ji research center of Fluid Machinery engineering and Technology Jiangsu University

With the increasing noise pollution, low noise optimization of centrifugal pimps has become a hot topic. However, experimental study on this problem is unacceptable for industrial applications due to unsustainable cost. A hybrid method that couples computational fluid dynamics （CFD） with computational aeroacoustic software is used to predict the flow-induced noise of pumps in order to minimize the noise of centrifugal pumps in actual projects. Under Langthjem＇s assumption that the blade surface pressure is the main flow-induced acoustic source in centrifugal pumps, the blade surface pressure pulsation is considered in terms of the acoustical sources and simulated using CFX software. The pressure pulsation and noise distribution in the near-cutoff region are examined for the blade-passing frequency （BPF） noise, and the sound pressure level （SPL） reached peaks near the cutoff that corresponded with the pressure pulsation in this region. An experiment is performed to validate this prediction. Four hydrophones are fixed to the inlet and outlet ports of the test pump to measure the flow-induced noise from the four-port model. The simulation results for the noise are analyzed and compared with the experimental results. The variation in the calculated noise with changes in the flow agreed well with the experimental results. When the flow rate was increased, the SPL first decreased and reached the minimum near the best efficient point （BEP）; it then increased when the flow rate was further increased. The numerical and experimental results confirmed that the BPF noise generated by a blade-rotating dipole roughly reflects the acoustic features of centrifugal pumps. The noise simulation method in current study has a good feasibility and suitability, which could be adopted in engineering design to predict and optimize the hydroacoustic behavior of centrifugal pumps.

关键词： centrifugal pumps flow-induced noise prediction blade-passing noise blade surface pressure pulsations

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effects of scandium addition on microstructure and mechanical properties of ZK60 alloy

引用

Progress in Natural Science:Materials International 2011年第1期21卷 59-65页

作者： Fu-sheng PAN~(1,2),Ting-ting LIU~(1,2),Xi-yan ZHANG~(1,2),Ai-tao TANG~(1,2),Wei-qing WANG~(1,2) 1.national engineering research center for Magnesium Alloys,Chongqing University,Chongqing 400045,China 2.College of Materials Science and engineering,Chongqing University,Chongqing 400045,China national engineering research center for Magnesium Alloys Chongqing University Chongqing 400045 China College of Materials Science and engineering Chongqing University Chongqing 400045 China

The effects of Sc addition on the microstructure and mechanical properties of the ZK60 wrought magnesium alloy were investigated by using optical microscope,scanning electron microscopy,X-ray diffraction and tensile *** experimental results show that a minor Sc addition to ZK60 alloy has an obvious effect on the refinement of the microstructure of the ZK60 alloy. During hot extrusion,incomplete dynamic recrystallization occurs in all the alloys,and the recrystallized grains become much finer with increasing Sc *** tensile strengths of ZK60 evidently increase with the addition of Sc,but the elongations decrease. The ZK60 alloy with 0.6%(mass fraction) Sc addition is found to have the tensile strength of about 350 MPa and the yield strength of about 280 *** T6 heat treatment,the tensile strength of the alloy containing 0.6%Sc remains almost ***, the yield strength of the alloy increases up to 352 MPa,and the ratio of the tensile strength to the yield strength is close to 1.

关键词： wrought magnesium alloy scandium microstructure mechanical properties

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：