期刊文献+
共找到1,014篇文章
< 1 2 51 >
每页显示 20 50 100
Novel Mechanical Interface Design for Automotive Starting Systems
1
作者 Alvaro C.Michelotti Jonny C.da Silva Lauro C.Nicolazzi 《Automotive Innovation》 EI CSCD 2019年第1期14-25,共12页
Stop-start vehicles(SSVs)represent a potential alternative for improving internal combustion engine(ICE)efficiency.SSVs provide ICEs with the functionality of turning the engine off during traffic halts and restarting... Stop-start vehicles(SSVs)represent a potential alternative for improving internal combustion engine(ICE)efficiency.SSVs provide ICEs with the functionality of turning the engine off during traffic halts and restarting it without intervention by the driver.This strategy reduces fuel consumption,especially in dense urban traffic areas,and contributes to emissions reduction to meet green emissions targets.The most widely adopted SSV system has a mechanical interface to connect the electric starter motor to the ICE,which requires increased robustness compared with standard starting motors.This requirement allows the motor to withstand a higher number of engine start cycles compared with a standard starting motor.Nevertheless,it is a critical problem for wider adoption of SSVs.As SSV systems usually are based on the conventional starting system,its durability and noise remains a critical issue to be addressed by automakers.The typical pinion-ring gear interface uses intermittent gear meshing to form a transient coupling interface.The research reported here presents the development of an innovative mechanical interface for starting systems,called the permanent coupling(PC)-type interface,which reduces noise and increases durability compared with the existing design.The results obtained by a functional prototype of the PC-type mechanical interface confirm the feasibility of the proposed concept.The methodology is based on a product development process integrated with lumped-parameter modeling and virtual simulation aimed at reducing failures during prototype test-ing.The new mechanical interface was proven to be a good candidate for increasing the use of SSVs in the automotive market. 展开更多
关键词 starting systems Internal combustion engines Stop-start vehicles Mechanical interface Lumped-parameter simulation
原文传递
Starting Characteristics of Motor in Inverter-Motor Drive System 被引量:1
2
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
Evaluation System and Method of Industrial Park Renewal:A Case Study of the Starting Area of Handan City
3
作者 ZHAO Ping GAO Ruihong +1 位作者 XUE Xiaona LI Wenya 《Journal of Landscape Research》 2022年第4期29-32,38,共5页
With the rapid development of urbanization,the industrial parks originally located in the suburbs are gradually incorporated into the urban center.Industries that fail to follow the transformation of urban economic de... With the rapid development of urbanization,the industrial parks originally located in the suburbs are gradually incorporated into the urban center.Industries that fail to follow the transformation of urban economic development and are forced to close,or enterprises that move out without conforming to the environment,become a gray area within the city.Most of the existing assessments are conducting single assessment of some indicators,but than their actual benefits.Through the field investigation on the starting area of Handan Economic Development Zone,and the evaluation on the nature of land use,development intensity,investment and output,and idle land,inefficient land use in the park is identified.According to different evaluation results,different update and promotion methods are put forward.The research could provide a new evaluation method and idea for subsequent renewal and development of urban industrial parks. 展开更多
关键词 Industrial park Inefficient land use Land use assessment starting area of Economic Development Zone
下载PDF
Review of Black Start on New Power System Based on Energy Storage Technology
4
作者 Jin Fan Litao Niu +8 位作者 Cuiping Li Gang Zhang He Li Yiming Wang Junhui Li Qinglong Song Jiacheng Sun Jianglong Pan Fangfang Lai 《Energy Engineering》 EI 2023年第12期2857-2878,共22页
With the continuous development of new energy generation technology and the increasingly complex power grid environment,the traditional black start scheme cannot meet the requirements of today’s power grid in order t... With the continuous development of new energy generation technology and the increasingly complex power grid environment,the traditional black start scheme cannot meet the requirements of today’s power grid in order to ensure the stable operation of the power system can be restored quickly in the face of large power outages,so a more complete black start scheme needs to be developed to cope with the new power system.With the development of energy storage technology,the limitations of the traditional black-start scheme can be solved by new energy farms with energy storage configuration.Therefore,this paper investigates the problems faced by black-start,the key technologies of energy storage assisted new energy black-start,and introduces the research related to new energy black-start technology to provide reference for future research and application of new energy black-start. 展开更多
关键词 New energy black start energy storage rapid recovery
下载PDF
Biological Profile of People Living with Human Immunodeficiency Virus Starting Treatment in Kinshasa, Democratic Republic of the Congo
5
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
6
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
Comparative evaluation of commercial Douchi by different molds:biogenic amines,non-volatile and volatile compounds 被引量:1
7
作者 Aijun Li Gang Yang +4 位作者 Zhirong Wang Shenglan Liao Muying Du Jun Song Jianquan Kan 《Food Science and Human Wellness》 SCIE CSCD 2024年第1期434-443,共10页
To provide new insights into the development and utilization of Douchi artificial starters,three common strains(Aspergillus oryzae,Mucor racemosus,and Rhizopus oligosporus)were used to study their influence on the fer... To provide new insights into the development and utilization of Douchi artificial starters,three common strains(Aspergillus oryzae,Mucor racemosus,and Rhizopus oligosporus)were used to study their influence on the fermentation of Douchi.The results showed that the biogenic amine contents of the three types of Douchi were all within the safe range and far lower than those of traditional fermented Douchi.Aspergillus-type Douchi produced more free amino acids than the other two types of Douchi,and its umami taste was more prominent in sensory evaluation(P<0.01),while Mucor-type and Rhizopus-type Douchi produced more esters and pyrazines,making the aroma,sauce,and Douchi flavor more abundant.According to the Pearson and PLS analyses results,sweetness was significantly negatively correlated with phenylalanine,cysteine,and acetic acid(P<0.05),bitterness was significantly negatively correlated with malic acid(P<0.05),the sour taste was significantly positively correlated with citric acid and most free amino acids(P<0.05),while astringency was significantly negatively correlated with glucose(P<0.001).Thirteen volatile compounds such as furfuryl alcohol,phenethyl alcohol,and benzaldehyde caused the flavor difference of three types of Douchi.This study provides theoretical basis for the selection of starting strains for commercial Douchi production. 展开更多
关键词 DOUCHI starting strains Non-volatile compounds Volatile compounds Sensory evaluation
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
8
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
Application of modified discontinuous deformation analysis to dynamic modelling of the Baige landslide in the Jinsha River
9
作者 XIE Chenxi DENG Jianhui +3 位作者 PENG Xinyan YANG Zhongkang ZHAO Siyuan LI Hua 《Journal of Mountain Science》 SCIE CSCD 2024年第7期2305-2319,共15页
Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating land... Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating landslides.However,DDA fails to accurately capture the degradation in shear strength of rock joints commonly observed in high-speed landslides.In this study,DDA is modified by incorporating simplified joint shear strength degradation.Based on the modified DDA,the kinematics of the Baige landslide that occurred along the Jinsha River in China on 10 October 2018 are reproduced.The violent starting velocity of the landslide is considered explicitly.Three cases with different violent starting velocities are investigated to show their effect on the landslide movement process.Subsequently,the landslide movement process and the final accumulation characteristics are analyzed from multiple perspectives.The results show that the violent starting velocity affects the landslide motion characteristics,which is found to be about 4 m/s in the Baige landslide.The movement process of the Baige landslide involves four stages:initiation,high-speed sliding,impact-climbing,low-speed motion and accumulation.The accumulation states of sliding masses in different zones are different,which essentially corresponds to reality.The research results suggest that the modified DDA is applicable to similar high-level rock landslides. 展开更多
关键词 Discontinuous deformation analysis(DDA) Baige landslide Violent starting velocity movement process Accumulation characteristics
下载PDF
《老年人潜在不适当处方筛查工具/处方遗漏筛查工具(STOPP/START)标准》第3版解读
10
作者 朱素燕 郑晓梦 +1 位作者 范苗 陈春燕 《中国全科医学》 CAS 北大核心 2024年第33期4097-4104,共8页
老年人潜在不适当处方筛查工具(STOPP)/处方遗漏筛查工具(START)由2008年爱尔兰Cork大学附属医院专家组首次发表并于2015年进行第2次更新。自发表以来,该标准在发现老年人潜在不适当用药、加强对老年人滥用药物的监管、减少老年人药品... 老年人潜在不适当处方筛查工具(STOPP)/处方遗漏筛查工具(START)由2008年爱尔兰Cork大学附属医院专家组首次发表并于2015年进行第2次更新。自发表以来,该标准在发现老年人潜在不适当用药、加强对老年人滥用药物的监管、减少老年人药品不良事件等方面发挥了积极作用。2023年第3版STOPP/START标准发布,在第2版基础上增加、修订和删减了一些标准,最终形成190条潜在不适当用药标准。新标准根据最新的老年人合理用药研究结果和临床证据,提供了更新、更实用的循证医学依据。本文对STOPP/START标准(第3版)进行了详细的解读,为我国潜在不适当用药标准更新和完善提供参考,并对未来该领域的研究方向提出思考和建议。 展开更多
关键词 潜在不当用药 老年人潜在不适当处方筛查工具 STOPP/START标准 老年人 多重用药 Beers标准
下载PDF
Visiting Village to Purchase Fine Products Series of Events of ‘2024 Travelling and Purchasing at Village’
11
《China & The World Cultural Exchange》 2024年第2期12-14,共3页
Series of events of"Rural Travelling and Shopping for Chinese New Year—2024 Travelling and Purchasing at Village"are focused on"joyful journey","colorful customs","happy temple fair... Series of events of"Rural Travelling and Shopping for Chinese New Year—2024 Travelling and Purchasing at Village"are focused on"joyful journey","colorful customs","happy temple fair"and"fine products for Chinese New Year",starting from January 16,and to be lasted till the Lantern Festival onFebruary24. 展开更多
关键词 VILLAGE RURAL starting
下载PDF
An Innovation Superpower in Making
12
作者 SU NAN 《ChinAfrica》 2024年第7期18-19,共2页
Shanghai is aptly utilising the new round of technological and industrial revolution to effectively revitalise its traditional industries Technological innovation is the starting point for the development of new quali... Shanghai is aptly utilising the new round of technological and industrial revolution to effectively revitalise its traditional industries Technological innovation is the starting point for the development of new quality productive forces.This process involves transforming traditional industries and nurturing emerging sectors,ultimately leading to a significant qualitative leap in productivity. 展开更多
关键词 starting qualitative productive
下载PDF
The Dragon Returns
13
作者 KIRTAN BHANA 《ChinAfrica》 2024年第3期38-38,共1页
The Chinese New Year celebrations highlight the importance of cultural connections.Africa is not just a geographical location;it’s a mosaic of ancient civilisations and indigenous knowledge blended with the dynamics ... The Chinese New Year celebrations highlight the importance of cultural connections.Africa is not just a geographical location;it’s a mosaic of ancient civilisations and indigenous knowledge blended with the dynamics of a modern society.These attributes create the right platform for growing China-Africa bonds.Many nations in the East celebrate the Spring Festival,or the Chinese New Year,which indicates the arrival of spring,a season that brings new life and reinvigorates one that is dormant.The festival has also been officially listed as a United Nations Floating Holiday in the UN Calendar of Conferences and Meetings starting in 2024. 展开更多
关键词 CALENDAR LISTED starting
下载PDF
要闻
14
《China's Tibet》 2024年第2期72-72,共1页
China announces visa-free policy for 6 European countries China will adopt a visa-free policy for Switzerland,lreland,Hungary,Austria,Belgium and Luxembourg on a trial basis,starting March 14,Chinese Foreign Minister ... China announces visa-free policy for 6 European countries China will adopt a visa-free policy for Switzerland,lreland,Hungary,Austria,Belgium and Luxembourg on a trial basis,starting March 14,Chinese Foreign Minister Wang Yi said on March 7.This will make it more convenient for Chinese citizens to travel abroad,and make foreign friends feel at home in China,he said. 展开更多
关键词 POLICY TRAVEL starting
下载PDF
让潍坊风筝飞向全世界
15
作者 涂丽平 《疯狂英语(新悦读)》 2024年第5期25-28,74,75,共6页
1 After a long,cold and dry winter,life and color are starting to return.Flowers are everywhere,birds are singing and people are flying kites.Known as the birthplace of kites,Weifang in Shandong Province has a long hi... 1 After a long,cold and dry winter,life and color are starting to return.Flowers are everywhere,birds are singing and people are flying kites.Known as the birthplace of kites,Weifang in Shandong Province has a long history of making kites.2 It is believed that Weifang kite⁃making can be traced back to 2000 years ago.At first,they were often used by the army for communication purposes.During the Ming Dynasty,kites started to be popular.Made from bamboo and covered with traditional Chinese paintings,Weifang kite⁃making was included in the intangible cultural heritage lists in 2006.The International Kite Festival has been held in Weifang every year since 1984. 展开更多
关键词 潍坊风筝 RETURN starting
下载PDF
Winning Hearts
16
《ChinAfrica》 2024年第3期44-45,共2页
Sinohydro and Senegal join forces to provide drinking water in Dakar.Sinohydro,a subsidiary of PowerChina,is currently engaged in efforts to substantially enhance the potable water supply in Dakar,Senegal.A diligent g... Sinohydro and Senegal join forces to provide drinking water in Dakar.Sinohydro,a subsidiary of PowerChina,is currently engaged in efforts to substantially enhance the potable water supply in Dakar,Senegal.A diligent group of Chinese and Senegalese workers is engaged in roundthe-clock efforts along the Avenue du Front de Terre prolongée,which marks the starting point of the Route des Pères Maristes,with the objective of improving the distribution network for potable water in the Dakar Department.With a population density of 7,277 inhabitants per square km and an estimated 1.18 million inhabitants in 2023,there is an evident and increasing need for potable water.This need is further compounded by significant water loss caused by the advanced age of the pipelines,with some pipes dating back to the colonial era. 展开更多
关键词 AVENUE starting NETWORK
下载PDF
Training Train Drivers
17
作者 DERRICK SILIMINA 《ChinAfrica》 2024年第2期36-37,共2页
As the train engine roars,doors of the wagons gently open at 07:30 a.m.,with crew members waiting for the passengers to board before starting the journey for their next destination.An hour before the departure,Marriam... As the train engine roars,doors of the wagons gently open at 07:30 a.m.,with crew members waiting for the passengers to board before starting the journey for their next destination.An hour before the departure,Marriam Gadesa heads to the locomotive cabin and quickly tests the locomotive’s power supply,and then starts the engine. 展开更多
关键词 starting DESTINATION TRAINING
下载PDF
Control System Development and Experimental Study on Ultrasonic Vibration Feeding 被引量:5
18
作者 ZENG Xianghui QI Lehua +2 位作者 HUANG Hua LI Yang YANG Fang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2011年第6期1083-1088,共6页
Ultrasonic vibration feeding(UVF) method which can quantitatively feed and precisely deposit fine powder is a potential technique for micro feeding.The excitation sources transmit vibration to capillary though the t... Ultrasonic vibration feeding(UVF) method which can quantitatively feed and precisely deposit fine powder is a potential technique for micro feeding.The excitation sources transmit vibration to capillary though the third medium for most UVF devices.The vibrator is directly touched with the capillary can transmit mechanical energy on the capillary as much as possible,and the powder feeding can be controlled more precise.However,there are few reports about it.A direct UVF system which integrates the function of micro feeding,process observing,and powder forming was developed in this work.In order to analyze the effect of the system factors on feeding,a group of L9(3^3) orthogonal experiments are selected to confirm the effect of level change of factors.The three factors are capillary nozzle diameter,amplitude and signal.The flow rate was stable for each combined factors,and the optimum combination for the minimum flow rate are choosing small capillary,small amplitude,and triangular wave orderly.The whole process of feeding includes start point,middle stage and stop stage.Starting of feeding was synchronized to vibration when the amplitude of capillary nozzle is larger than critical amplitude.Then,the feeding process enters the middle stage,the feeding state is observed by the CCD,and it is very stable in the middle stage.Overflow of feeding can't be eliminated during the stop stage.The features of the deposited powder lines are analyzed; the overflow can be diminished by choosing small capillary and appropriate ratio of the capillary nozzle diameter to the particle size.Chinese characters lattices were deposited to validate the ability of quantitatively feeding and fixed feeding of UVF.Diameters of all powder dots show normal distribution,and more than 60% dots are concentrated from 550 μm to 650 μm,and the average diameter for all the dots is 597 μm.Most dots positions are well approached to their scheduled positions,and the maximum deviation is 0.27 mm.The new direct UVF system is used to implement experiments,which confirms the precise controllable of feeding.According improve the feeding technique,it suits well for rapid prototyping,chemistry,pharmaceutics and many other fields,which require precise measurement and feed minim powder. 展开更多
关键词 ultrasonic vibration feeding (UVF) CAPILLARY orthogonal experiment start/stop control quantitatively feeding fixed feeding
下载PDF
Experimental study of the critical sand starting velocity of gas-watersand flow in an inclined pipe 被引量:2
19
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
Reconstruction of the starting time series of rainy season in Yunnan and the evolvement of summer monsoon during 1711-1982 被引量:2
20
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
上一页 1 2 51 下一页 到第
使用帮助 返回顶部