期刊文献+
共找到1,007篇文章
< 1 2 51 >
每页显示 20 50 100
Biological Profile of People Living with Human Immunodeficiency Virus Starting Treatment in Kinshasa, Democratic Republic of the Congo
1
作者 Berry Ikolango Bongenya Marie-Thérèse Ayanne Safi Sombo +5 位作者 Guy Makila Mabe Bumoko Benoit Obel Kabengele Fridolin Kule-Koto Kodondi Baudoin Bu-Tsumbu Buassa Richard Lunganza Kalala Erick Ntambwe Kamangu 《World Journal of AIDS》 2023年第1期1-10,共10页
Context: The biochemical assessment is a real-time indicator of the state and evolution of an infection. Among other things, it makes it possible to determine the right moment when it becomes necessary to start or cha... Context: The biochemical assessment is a real-time indicator of the state and evolution of an infection. Among other things, it makes it possible to determine the right moment when it becomes necessary to start or change a treatment. Objective: The objective of this study is to present the Biological profile of People Living with HIV starting AntiRetroViral treatment in Kinshasa in the era of Dolutegravir. Methods: The present study is a descriptive cross-sectional to determine the biological profile of People Living with HIV (PLHIV) starting AntiRetroViral Treatment (ART). The patient inclusion period was from October 4, 2021 to February 15, 2022. Sixteen centers were included. A sample of 5 ml of blood was taken in a tube with EDTA. Patients were randomly included consecutively in the centers during consultations. The population was made up of adults aged over 18, infected with HIV and starting ART. The parameters of interest retained for the present study were: sex, age, hemoglobin level, blood sugar, urea, creatinine, transaminases, total cholesterol, triglycerides, proteins total, as well as amylase. Results: 119 patients were included in this study in accordance with the inclusion criteria;67 (56.3%) are female, giving a sex ratio of 1.29 in favor of women. The average age of the patients is 39.87 ± 12.36 years. The most represented age group is that of 36 to 45 years with 37 patients (31.9%). The mean values of the biological parameters of the patients at the start of ART are as follows: 31.61 ± 20.71 IU/L for ALT/SGPT, 25.81 ± 19.96 IU/L for AST/SGOT, 79.35 ± 49.49 IU/L for Amylase, 108.13 ± 62.17 mg/dl for Total Cholesterol, 2.77 ± 1.27 mg/dl for Creatinine, 72.53 ±22.23 mg/dl for Glycaemia, 10.30 ± 2.33 g/dl for Hemoglobin, 7.91 ± 1.75 g/dl for Total Protein, 131.23 ± 68.80 mg/dl for Triglycerides, and 33.61 ± 26.27 mg/dl for Urea. Conclusion: Mean values of PLHIV are, for the most part, within the normal range. The average creatinine is higher than the normal average value while the average total cholesterol is below the limit values. 展开更多
关键词 Biological Profile PLHIV starting ART KINSHASA
下载PDF
Virological and Molecular Profile of People Living with the Human Immunodeficiency Virus Starting Dolutegravir Based Antiretroviral Treatment in Kinshasa, Democratic Republic of Congo
2
作者 Berry I. Bongenya Charlotte L. Tshinguta +4 位作者 Marie-Thérèse A. S. Sombo Guy M. M. Bumoko Benoit O. Kabengele Gauthier K. Mesia Erick N. Kamangu 《World Journal of AIDS》 2023年第3期83-94,共12页
Context: Despite the new recommendations “Test and Treat”, the virological and molecular parameters remain important information for Antiretroviral Treatment and adequate for monitoring of patients infected with HIV... Context: Despite the new recommendations “Test and Treat”, the virological and molecular parameters remain important information for Antiretroviral Treatment and adequate for monitoring of patients infected with HIV/AIDS. Objective: the Objective of this study is to present the virological and molecular profile of People Living with HIV starting Antiretroviral Therapy in Kinshasa in the era of the Dolutegravir. Methods: This was a transversal study to determine virological and molecular profile of People Living with HIV (PLHIV) starting an ARV Treatment. The patient’s inclusion period was from October 04, 2021 to February 15, 2022. A sample of 5 ml of blood was taken in a tube with EDTA anticoagulant for Molecular Biology analyzes (Viral Load and Sequencing) in all HIV patients, after reading and signing informed consent. The population was made up of adult patients over the age of 18, infected with HIV and starting ART. Results: 119 patients (56.3% of women) were included in this study, thus a sex-ratio of 1.29. The average age of patients included was 39.87 ± 12.36 years. The most represented age group is that of 36 to 45 with 37 patients (31.9%) followed by that from 26 to 35 years with 24 patients (20.7%). Out of 119 patients, 21 patients had an undetectable Viral Load (VL). The median value of VL was 4.16 log10 RNA copies/ml. 114 samples were successfully amplified. Subtype A was dominant with 23 cases (20.2%);followed by the subtype C and CRF02_AG each with 14.0%, and D (10.5 %). K65R (1.8%), T69P/N (4.4%), K70R (7.9%) and M184V (7.0%) mutations were listed as existing mutations for Nucleotide Transcriptase Inhibitors. Conclusion: 38 patients (31.93%) started the TARV with a positive virological prognosis. The subtype A remains dominant in Kinshasa with 23 cases (20.2%);followed by the subtype C and CRF02_AG each with 14.0%. For Inhibitors of Transcriptase Reverse Nucleotide;K65R, T69P/N, K70E/R and M184V mutations were found in patients’ naive of ARV Treatment. 展开更多
关键词 Virological Profile Molecular Profile PLHIV Start of ART KINSHASA
下载PDF
追求卓越的早期教育质量--OECD早期保教质量调查报告“Starting StrongⅢ”述评 被引量:2
3
作者 周玉娥 刘智成 《外国教育研究》 CSSCI 北大核心 2013年第6期11-16,共6页
早期教育质量的影响因素是多方面的,OECD成员国在提高早期教育质量方面作了许多积极探索,Starting StrongⅢ就是在广泛调研基础上形成的一份聚焦质量的报告。通过探讨Starting StrongⅢ的形成背景,进而分析其五个与早期教育质量密切相... 早期教育质量的影响因素是多方面的,OECD成员国在提高早期教育质量方面作了许多积极探索,Starting StrongⅢ就是在广泛调研基础上形成的一份聚焦质量的报告。通过探讨Starting StrongⅢ的形成背景,进而分析其五个与早期教育质量密切相关的重要政策杠杆,能为思考我国学前教育发展提供些许启示。 展开更多
关键词 早期教育和保育 质量 starting StrongⅢ
下载PDF
Reconstruction of the starting time series of rainy season in Yunnan and the evolvement of summer monsoon during 1711-1982 被引量:2
4
作者 YANG Yuda MAN Zhimin ZHENG Jingyun 《Journal of Geographical Sciences》 SCIE CSCD 2007年第2期212-220,共9页
According to the textual research into the historical documents dominated by archives yearly, as well as the verification with several other kinds of data, the later or earlier starting time of the rainy seasons in Yu... According to the textual research into the historical documents dominated by archives yearly, as well as the verification with several other kinds of data, the later or earlier starting time of the rainy seasons in Yunnan during 1711-1982 has been reconstructed. The analysis indicates that there are obvious fluctuations in the starting date of the rainy seasons in Yunnan in a year or years, and long fluctuation on the decadal scale. The rainy season comes earlier in the early 18th century, later in the 19th century and earlier again in the 20th century. This reflects to a certain degree the gradual change of the summer monsoon in Yunnan. There exists an obvious quasi-3 years cycle, which is related to EI-Nino's quasi-3 years cycle, and a 11.3-year cycle which is notably related to the 11-year cycle of the solar activity of starting date of the rainy seasons in Yunnan. Meanwhile, the dissertation finds that the EI-Nino is very important to the starting date of the rainy seasons in Yunnan. The starting date of the rainy seasons in Yunnan often comes later or normally in the year of EI-Nino. However, there is an obvious imperfect period in such influence, which in turn may mean that there is a certain fluctuation in the effect of ENSO on Asian summer monsoon. 展开更多
关键词 YUNNAN Qing Dynasty starting date of rainy season summer monsoon ENSO
下载PDF
Simulation study on starting of dual clutch transmission for tracked vehicles 被引量:1
5
作者 张金乐 马彪 +1 位作者 张英锋 郑长松 《Journal of Beijing Institute of Technology》 EI CAS 2011年第1期77-83,共7页
In order to study the application of dual clutch transmission (DCT) on tracked vehicles, a simulation moclel and two control methods were performed for starting analysis. Based on a certain transmission of an existi... In order to study the application of dual clutch transmission (DCT) on tracked vehicles, a simulation moclel and two control methods were performed for starting analysis. Based on a certain transmission of an existing tracked vehicle, a DCT structure was proposed. Matlab/Simulink was a dopted as a platform to develop the simulation model. The engine speed was controlled to follow the target speed as a launch strategy. Two control methods, a proportional integral derivative ( PID ) control method and a fuzzy control method, were proposed to control the engine throttle and oil pressure in order to track the target engine speed. Simulation results show that either the PID control or fuzzy control method can improve the starting performance compared with no loop control meth od. Fuzzy control method can lead a better starting quality compared with PID control method. 展开更多
关键词 starting control dual clutch transmission proportional integral derivative (PID) fuzz y tracked vehicle
下载PDF
Starting flow in a rotating parallel plate channel 被引量:1
6
作者 Chang Yi Wang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第5期1271-1276,共6页
The starting flow due to a suddenly applied pressure gradient in a parallel plate channel which is rotating as a system is studied. Exact analytic series solutions to the unsteady Navier-Stokes equations are found by ... The starting flow due to a suddenly applied pressure gradient in a parallel plate channel which is rotating as a system is studied. Exact analytic series solutions to the unsteady Navier-Stokes equations are found by both the Laplace transform method and the separation of parameters method, the latter is shown to be superior. Rotation not only induces a secondary transverse flow but also alters the character of the transient flow rate and velocity profiles. Back flow and inertial oscillations occur, especially at higher rota- tion rates. 展开更多
关键词 Rotating system Flow - starting
下载PDF
Starting Characteristics of Motor in Inverter-Motor Drive System 被引量:1
7
作者 Xi-jun Yang Xiang-jun Zhang You-min Gong 《Advances in Manufacturing》 2000年第2期140-144,共5页
When the induction motor is fed from the PWM VSI inverter, with and without torque enhancing function, the variations of the starting torque and the starting current versus the starting frequency are analyzed, base... When the induction motor is fed from the PWM VSI inverter, with and without torque enhancing function, the variations of the starting torque and the starting current versus the starting frequency are analyzed, based on the steady state equivalent circuit of the induction motor.The corresponding expressions are derived, and the corresponding curves are also drawn, from which the initial starting frequency range can be determined properly and easily. The initial starting frequency range is the common range, in which the starting torque should be high enough and the starting current low enough.Some other useful formulas are also derived.These results are significant for electrical drive designers to make the starting schemes. The effects of the increase of the stator and the rotor resistances on the starting torque and the initial starting frequency range are also discussed, which is caused by the skin effects of the high order harmonics present in the PWM inverter output voltage. 展开更多
关键词 inverter motor drive system starting characteristics skin effect
下载PDF
Commentary on: “Scientific evidence is just the starting point:A generalizable process for developing sports injury prevention interventions” by Alex Donaldson et al.
8
作者 Eva Ageberg 《Journal of Sport and Health Science》 SCIE 2016年第3期322-323,共2页
<正>In a recent paper,Donaldson et al.~1 argued that lower extremity injuries can be prevented.Evidence-based sports injury preventive exercise programs usually have limited impact on public health because they ... <正>In a recent paper,Donaldson et al.~1 argued that lower extremity injuries can be prevented.Evidence-based sports injury preventive exercise programs usually have limited impact on public health because they are not widely adopted or sustained into regular training routines.One reason for this is that the intervention program may not seem relevant for the 展开更多
关键词 sports COMMENTARY on SUSTAINED exercise EXTREMITY starting injuries prevention PREVENTIVE programs
下载PDF
THE EVOLUTION OF STARTING VORTEX AND SECONDARY SEPARATION ON AN ELLIPTIC CYLINDER
9
作者 Zhang Dieli (Institute of Mechanics,Academia Sinica) 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1989年第1期20-30,共11页
Flow visualization was used to investigate experimentally the evolution process from symmetrical shedding to staggered shedding of the starting vortex and the phenomenon of secondary separation on an elliptic cylinder... Flow visualization was used to investigate experimentally the evolution process from symmetrical shedding to staggered shedding of the starting vortex and the phenomenon of secondary separation on an elliptic cylinder at moderate Reynolds numbers.The vortex structure of the flow separation was studied.The temporal variation of separation angle and length of wake vortex were given. The photographs and experimental results provided basis for further investigation of the complicated feature of the starting process of unsteady separated flows around an elliptic cylinder. 展开更多
关键词 unsteady separated flows starting vortex secondary vortex secondary separation staggered shedding of vortex
下载PDF
Experimental study of the critical sand starting velocity of gas-watersand flow in an inclined pipe
10
作者 Rui-Yao Zhang Jun Li +3 位作者 Hong-Wei Yang Geng Zhang Xi-Ning Hao Peng-Lin Liu 《Petroleum Science》 SCIE CAS CSCD 2022年第6期2981-2994,共14页
The purpose of this paper is to study the critical sand starting velocity and transformation law of flow pattern based on gas-water-sand three-phase flow in an inclined pipe.Firstly,the indoor simulation experiment sy... The purpose of this paper is to study the critical sand starting velocity and transformation law of flow pattern based on gas-water-sand three-phase flow in an inclined pipe.Firstly,the indoor simulation experiment system of gas-water-sand three-phase flow was used to test the conversion law of flow pattern based upon the different gas void fraction.Secondly,the influence of slug bubbles on sand migration was investigated according to distinctive hole deviation angles,gas void fraction and sand concentration.Finally,the critical sand starting velocity was tested based on dissimilar hole deviation angles,gas void fraction,sand concentration and sand particle size,and then the influence of the abovementioned key parameters on the sand starting velocity was debated based on the force analysis of the sand particles.The experimental results illustrated that when the gas void fraction was less than 5%,it was bubbly flow.When it increased from 5%to 30%,the bubbly flow and slug flow coexisted.When it was between 30%and 50%,the slug flow and agitated flow coexisted.When it reached 50%,it was agitated flow.Providing that the hole deviation angle was 90°,the phenomenon of overall migration and wavelike migration on the surface of sand bed was observed.On the contrary,the phenomenon of rolling and jumping migration was recognized.The critical sand starting velocity was positively correlated with the hole deviation angle and sand particle size,but negatively associated with the gas void fraction and sand concentration.This research can provide a certain reference for sand-starting production in the field of petroleum engineering. 展开更多
关键词 Three-phase flow Critical sand starting velocity Flow pattern Sand migration Gas void fraction Hole deviation angles Sand concentration
下载PDF
STUDY OF THE STARTING CURRENT AND FREQUENCY DEVIATION OF ELECTROSTATIC GYROMONOTRON
11
作者 于善夫 徐晓曦 刘盛纲 《Journal of Electronics(China)》 1991年第2期169-174,共6页
From relativistic linear Vlasov-Maxwell equations,the expressions of the startingcurrent and frequency deviation of a electrostatic gyromonotron with a field distribution sin k‖zare derived and the numerical calculat... From relativistic linear Vlasov-Maxwell equations,the expressions of the startingcurrent and frequency deviation of a electrostatic gyromonotron with a field distribution sin k‖zare derived and the numerical calculation is carried out. 展开更多
关键词 ELECTROSTATIC ELECTRON CYCLOTRON RESONANCE MASER ELECTROSTATIC gyromonotron starting current Frequency deviation
下载PDF
Analysis of static structural mechanics of vertical axis wind turbine with lift-drag combined starting structures
12
作者 QU Chunming FENG Fang +2 位作者 LI Yan BAI Yuedi ZHAO Bin 《排灌机械工程学报》 CSCD 北大核心 2021年第9期923-928,共6页
The finite element analysis was carried out for a composite vertical axis wind turbine with lift-drag combined starting structures to ensure the structure safety of a vertical axis wind turbine(VAWT).The static and mo... The finite element analysis was carried out for a composite vertical axis wind turbine with lift-drag combined starting structures to ensure the structure safety of a vertical axis wind turbine(VAWT).The static and modal analysis of rotor of a composite vertical axis wind turbine was conducted by using ANSYS software.The relevant contour sketch of stress and deformation was obtained.The analysis was made for static structural mechanics,modal analysis of rotor and the total deformation and vibration profile to evaluate the influence on the working capability of the rotor.The analysis results show that the various structure parameters lie in the safety range of structural mechanics in the relative standards.The analysis showing the design safe to operate the rotor of a vertical axis wind turbine.The methods used in this study can be used as a good reference for the structural mechanics′analysis of VAWTs. 展开更多
关键词 vertical axis wind turbine finite element analysis static structural mechanics lift-drag combined starting structure model analysis
下载PDF
MODELLING THE POLYALANINE BACKBONE STARTING FROM ALPHA-CARBON GUIDE POSITIONS
13
作者 Yu LUO Xu Liang JIANG Lu Hua LAI Chun Xu QU Xiao Jie XU You Qi TANG Institute of Physical Chemistry,Peking University,Beijing 100871 《Chinese Chemical Letters》 SCIE CAS CSCD 1990年第1期87-90,共4页
An automatic procedure for building a protein polyalanine backbone from guiding alpha-carbon positions is presented here,which is different from a previously developed'spare parts'approach(Jones and Thirup,198... An automatic procedure for building a protein polyalanine backbone from guiding alpha-carbon positions is presented here,which is different from a previously developed'spare parts'approach(Jones and Thirup,1986;Claessens et al.,1989). In our procedure,the geometric restraint of angle N-CA-C is used to generate a list of polypeptide chains,and several filters are used later to select the best conformer.The most important filter is based upon the Ramachandran scatter plot of mainchain dihedral angles PHI and PSI.Results for all test cases are satisfactory,with more than 95%of peptide planes correctly reconstructed and the overall root-mean-square deviation less than 0.5 angstrom compared with the refined X-ray coordinates. 展开更多
关键词 Bank MODELLING THE POLYALANINE BACKBONE starting FROM ALPHA-CARBON GUIDE POSITIONS length maps
下载PDF
Analysis of Starting Performance of High PowerFactor Induction Motor with Floating Windingin Parallel Connection with Capacitors
14
作者 ZHANG Qi XIE Guo dong (School of Automation, Shanghai University) 《Advances in Manufacturing》 SCIE CAS 1999年第4期299-303,共5页
In this paper, by using a matrix technique, a dynamic model of high power factor induction motor with floating winding in parallel connection with capacitors is established. Then, the starting performance of this mot... In this paper, by using a matrix technique, a dynamic model of high power factor induction motor with floating winding in parallel connection with capacitors is established. Then, the starting performance of this motor is analyzed by computer simulation. By comparison of the tested and computed results, which are in good agreement, the dynamic model and simulative method are verified. 展开更多
关键词 high power factor starting performance computer simulation
下载PDF
To Promote Scientific and Technological Innovation from Higher Starting Point
15
作者 Lou Qinjian Vice-Minister,Ministry of Industry and Information Technology,PRC 《China Communications》 SCIE CSCD 2008年第4期88-88,共1页
The year of 2008 has been a time of achieving major victory besides withstanding enormous challenges for the economic and social development of China. Under the correct leadership of the Party Central
关键词 INNOVATION MORE To Promote Scientific and Technological Innovation from Higher starting Point
下载PDF
Starting of HPS lamps driven by electronic ballast
16
作者 张伟强 王卫 徐殿国 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2001年第4期353-356,共4页
A complete research of two different starting techniques for HPS lamps driven by electronic ballast is presented while a traditional starting technique based on the series resonant theory which is used widely for fluo... A complete research of two different starting techniques for HPS lamps driven by electronic ballast is presented while a traditional starting technique based on the series resonant theory which is used widely for fluorescent lamps starting is analyzed in detail. An improved nth harmonic resonant technique is also simulated. Furthermore, a novel starting technique based on a pulse transformer is proposed, which still offer the automatic switch off capability. The differences between two starting techniques are explained. The experimental results from a lab prototype are used to verify the design. 展开更多
关键词 electronic ballast HPS lamp starting technique
下载PDF
Application of the Probability Model for Starting Period to Initiate to Take Palivizumab by Prefecture Using National Official Sentinel Surveillance in Japan
17
作者 Junko Kurita Tamie Sugawara +1 位作者 Yasushi Ohkusa Michiko Nohara 《Journal of Biosciences and Medicines》 2020年第1期56-63,共8页
Background: Palivizumab were used for the premature infant or a high-risk infant with congenital heart disease. However, recently outbreak pattern of respiratory syncytial (RS) virus infection has been varying year by... Background: Palivizumab were used for the premature infant or a high-risk infant with congenital heart disease. However, recently outbreak pattern of respiratory syncytial (RS) virus infection has been varying year by year. Moreover, it also has some regional difference. Therefore, the object of the present study was to develop early detection of the timing of that outbreak had started in each prefecture. Method: We used data in National Official Sentinel Surveillance for Infectious Diseases (NOSSID). Study period was March 16th, 2011 to December 30th, 2018. We defined stating period to initiate to take palivizumab as 8 - 12 weeks before from the peak of outbreak. We estimated whether the week is included in starting period or not from April 1st to the peak of outbreak by the past number of patients of RS virus infection on week and its squared. Additionally, we have to take delay in NOSSID into consideration. Results: In nationwide, the last two seasons, the model predicted precisely the starting period. At prefectural level, the model predicted the starting period precisely in 16.6% of all year and prefectures pairs. When we consider the delay in NOSSID into consideration, the patients can start to take in 14.9% of all year and prefectures pairs. Discussion and Conclusion: The result of the probability model was not good, and thus we have to develop more sophisticated model for prediction at prefecture level. 展开更多
关键词 Respiratory Syncytial Virus Infection NATIONAL OFFICIAL SENTINEL Surveillance PALIVIZUMAB Probability Model starting PERIOD
下载PDF
Dose-response relationship of lung cancer to amount smoked, duration and age starting
18
作者 John S Fry Peter N Lee +1 位作者 Barbara A Forey Katharine J Coombs 《World Journal of Meta-Analysis》 2013年第2期57-77,共21页
AIM: To quantify smoking/lung cancer relationships accurately using parametric modelling. METHODS: Using the International Epidemiological Studies on Smoking and Lung Cancer database of all epidemiological studies of ... AIM: To quantify smoking/lung cancer relationships accurately using parametric modelling. METHODS: Using the International Epidemiological Studies on Smoking and Lung Cancer database of all epidemiological studies of 100+ lung cancer cases published before 2000, we analyzed 97 blocks of data for amount smoked, 35 for duration of smoking, and 27 for age started. Pseudo-numbers of cases and controls(or at risk) estimated from RRs by dose level formed the data modelled. We fitted various models relating loge RR to dose(d), including βd, βdY and βloge(1 + Wd),and investigated goodness-of-fit and heterogeneity between studies. RESULTS: The best-fitting models for loge RR were0.833 loge [1 +(8.1c/10)] for cigarettes/d(c), 0.792(y/10)0.74 for years smoked(y) and 0.176 [(70- a)/10]1.44 for age of start(a). Each model fitted well overall, though some blocks misfitted. RRs rose from 3.86 to 22.31 between c = 10 and 50, from 2.21 to 13.54 between y = 10 and 50, and from 3.66 to 8.94 between a = 30 and 12.5. Heterogeneity(P < 0.001) existed by continent for amount, RRs for 50 cigarettes/d being 7.23(Asia), 26.36(North America) and 22.16(Europe). Little heterogeneity was seen for duration of smoking or age started. CONCLUSION: The models describe the dose-relationships well, though may be biased by factors including misclassification of smoking status and dose. 展开更多
关键词 SMOKING Lung neoplasms DOSE-RESPONSE Meta-analysis Review AMOUNT SMOKED DURATION of SMOKING Age at starting to smoke
下载PDF
A sensitive method for the quantitation of immunoglobulin G in starting materials of plasma fractionation
19
《中国输血杂志》 CAS CSCD 2001年第S1期363-,共1页
关键词 IMMUNOGLOBULIN FRACTIONATION starting
下载PDF
Effects of relaxation time on start-up time for starting flow of Maxwell fluid in a pipe
20
作者 Zhen Li Keqin Zhu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第2期209-215,共7页
Although the analytical solution of the starting flow of Maxwell fluid in a pipe has been derived for a long time, the effect of relaxation time λ on start-up time ts of this flow is still not well understood. Especi... Although the analytical solution of the starting flow of Maxwell fluid in a pipe has been derived for a long time, the effect of relaxation time λ on start-up time ts of this flow is still not well understood. Especially, there exist a series of jumps on the ts-λ. curve. In this paper we introduce a normalized mechanical energy by mode decomposition and mathematical analogy to describe the start-up process. An improved definition of start-up time is presented based on the normalized mechanical energy. It is proved that the ts-λ. curve contains a series of jumps if λ is larger than a critical value. The exact positions of the jumps are determined and the physical reason of the jumps is discussed. 展开更多
关键词 Maxwell fluid starting flow·Relaxation time·Start-up time·Mechanical energy
下载PDF
上一页 1 2 51 下一页 到第
使用帮助 返回顶部