期刊文献+
共找到18篇文章
< 1 >
每页显示 20 50 100
对散热器试验国际标准中有关规定的探讨 被引量:1
1
作者 董重成 《哈尔滨建筑工程学院学报》 1992年第1期68-72,共5页
本文对国际标准ISO3148,3149中的有关规定进行了分析,认为:实验小室的换气次效和安装散热器后墙的热阻不同将造成各实验台之间测试结果的差别。为减小各实验台之间的测试差别,建议ISO3148,3149中应规定闭式小室的换气次数不大于0.1次/时... 本文对国际标准ISO3148,3149中的有关规定进行了分析,认为:实验小室的换气次效和安装散热器后墙的热阻不同将造成各实验台之间测试结果的差别。为减小各实验台之间的测试差别,建议ISO3148,3149中应规定闭式小室的换气次数不大于0.1次/时;风冷闭式小室安装散热器的后墙也应装设隔热板,并使所测散热器对应墙面的热流量不高于其它壁面的平均值。 展开更多
关键词 实验小室 闭式小室 换气次数 后墙 隔热板 散热器 国际标准 测试
下载PDF
脊髓康含药血清对脂多糖诱导的小胶质细胞迁移功能的影响 被引量:2
2
作者 郭杨 苑文超 +4 位作者 潘娅岚 马勇 徐桂华 王磊 刘家欢 《时珍国医国药》 CAS CSCD 北大核心 2019年第12期2882-2885,共4页
目的观察中药复方脊髄康(JSK)含药血清对脂多糖(LPS)诱导的小胶质细胞迁移功能的影响。方法采用摇床法提取原代小肢质细胞进行培养、鉴定;制备JSK含药血清;将小肢质细胞分为空白血清组、LPS组、JSK低、中、高剤量组、黄芪甲苷(AS-IV)组... 目的观察中药复方脊髄康(JSK)含药血清对脂多糖(LPS)诱导的小胶质细胞迁移功能的影响。方法采用摇床法提取原代小肢质细胞进行培养、鉴定;制备JSK含药血清;将小肢质细胞分为空白血清组、LPS组、JSK低、中、高剤量组、黄芪甲苷(AS-IV)组;选取细胞划痕实验、Transweil小室迁移实验、鬼笔环肽免疫荧光实验对LPS诱导后的原代小胶质细胞的迁移功能进行检测。结果空白血清组、JSK低、中、高剂量组、AS-IV组小胶质细胞的迁移能力均低于LPS组(P<0.01);JSK高刑量组、AS-IV组小肢质细胞的迁移能力均低于JSK低、中剂量组(P<0.05);JSK高剂量组与AS-IV组相比无明显差异(P>0.05)。结论中药复方脊髓康(JSK)含药血清对LPS诱导的小胶质细胞迁移功能具有一定的抑制作用,从抑制小肢质细胞迁移的角度为中医药治疗脊敌损伤提供一定的依据。 展开更多
关键词 脊髓康 含药血清 小胶质细胞 迁移 划痕实验 Transwell小室迁移实验 鬼笔环肽免疫荧光实验
下载PDF
The Quality Evaluation of Two Chinese Leading Wheat Varieties in Europe Laboratory
3
作者 曹文昕 万映秀 +2 位作者 张琪琪 李炎 张平治 《Agricultural Science & Technology》 CAS 2016年第6期1510-1512,共3页
[Objective] The objective was to research the quality evaluation of Chinese wheat variety which analyzed in Europe laboratory, discuss the quality analysis standard of different countries. [Method] Two leading varieti... [Objective] The objective was to research the quality evaluation of Chinese wheat variety which analyzed in Europe laboratory, discuss the quality analysis standard of different countries. [Method] Two leading varieties (Yangnong19, Jimai22) of Huanghuai wheat area from China were analyzed in Cra-w (Walloon Agricultural Research Centre). [Result] Yannong19 corresponds to amuchstronger flour with a far better gluten quality. It could be used for bread making. It could also be used to produce good quality gluten. Jimai22 is not suitable for bread making but would probably be better for noodles production. [Conclusion] Protein results which come from NIR instrument are over estimating the content. This is probably due to the fact that Europe instruments are calibrated with European wheat. 展开更多
关键词 WHEAT Quality analyze Europe laboratory
下载PDF
二氢杨梅素对绒毛膜癌细胞增殖和迁移能力的影响 被引量:5
4
作者 雷赟涛 刘镭 +5 位作者 左彦珍 许倩 鲁艳杰 王康 崔莹 李玉红 《解剖学报》 CAS CSCD 北大核心 2019年第3期317-323,共7页
目的探讨二氢杨梅素(DMY)对绒毛膜癌(绒癌)JEG-3及JAR细胞增殖和迁移能力的影响。方法 MTT法检测不同浓度的二氢杨梅素(0 mg/L, 20 mg/L, 40 mg/L, 60 mg/L, 80 mg/L)作用一定时间后,对绒癌JEG-3和JAR细胞增殖能力的影响;细胞划痕实验和... 目的探讨二氢杨梅素(DMY)对绒毛膜癌(绒癌)JEG-3及JAR细胞增殖和迁移能力的影响。方法 MTT法检测不同浓度的二氢杨梅素(0 mg/L, 20 mg/L, 40 mg/L, 60 mg/L, 80 mg/L)作用一定时间后,对绒癌JEG-3和JAR细胞增殖能力的影响;细胞划痕实验和Transwell法检测不同浓度二氢杨梅素(0 mg/L, 40 mg/L, 60 mg/L, 80 mg/L)分别作用绒癌JEG-3细胞及JAR细胞一定时间后,对其迁移能力的影响;Real-time PCR和Western blotting方法分别检测不同浓度二氢杨梅素(0 mg/L, 40 mg/L, 60 mg/L, 80 mg/L)作用绒癌JEG-3及JAR细胞后,基质金属蛋白酶2(MMP-2)mRNA和蛋白表达水平的影响。结果不同浓度二氢杨梅素作用绒癌JEG-3和JAR细胞24 h和48 h后,随着二氢杨梅素浓度增加,对JEG-3和JAR细胞增殖抑制作用增强(P<0.05)。二氢杨梅素作用绒癌JEG-3及JAR细胞后,显著抑制细胞迁移能力,且具有浓度依赖性(P<0.05)。不同浓度二氢杨梅素作用JEG-3和JAR细胞后,MMP-2的mRNA和蛋白表达水平明显下降(P<0.05)。结论二氢杨梅素能够抑制JEG-3及JAR细胞的增殖能力且具有浓度依赖性,同时二氢杨梅素可能通过下调绒癌JEG-3及JAR细胞中MMP-2 mRNA和蛋白的表达,抑制绒癌细胞的侵袭迁移。 展开更多
关键词 绒毛膜癌 二氢杨梅素 增殖 迁移 迁移小室实验 实时定量聚合酶链反应
下载PDF
Effects of Collagen Peptide from Cyanea nozakii on Mouse Immune Function 被引量:1
5
作者 邓超 汤鲁宏 +2 位作者 陈伟 王琪 林丹 《Agricultural Science & Technology》 CAS 2009年第2期118-121,共4页
[Objective ] The study aimed to provide a theoretical basis for the clinical application of collagen peptide from Cyanea nozakii. [ Method] After acute toxicity test on mice, collagen peptide from C. nozakii were give... [Objective ] The study aimed to provide a theoretical basis for the clinical application of collagen peptide from Cyanea nozakii. [ Method] After acute toxicity test on mice, collagen peptide from C. nozakii were given to mice by continuous intragastric administration for 30 d at the doses of 25, 50, 100 mg/kg, and then the phagocytosis of macrophage, delayed type hypersensitivity (DTH) and serum hemolysin level were determined. [ Result] Collagen peptide from C. nozakii was atoxic or low toxic, and the three immune indices of experimental groups were signifi- canUy higher than those of the control group (treated with same volume of normal saline) at 0.05 or 0.01 level. E Conclusion] Collagen peptide from C. nozakii has a certain immunopotentiation. 展开更多
关键词 Cyanea nozakii Collagen peptide IMMUNOPOTENTIATION
下载PDF
Neuropilin-1的干扰RNA对胃癌细胞株AGS生物学行为的影响
6
作者 方圆 徐卫国 +7 位作者 齐艳涛 杨少君 徐洪 杨鑫 赵跃鹏 梁君伟 李君辉 刘和亮 《现代肿瘤医学》 CAS 2016年第22期3539-3542,共4页
目的:探讨神经纤毛蛋白-1(neuropilin-1,NRP-1)的小干扰RNA(small interfering RNA,siRNA)对人胃腺癌细胞株AGS某些生物学行为的影响。方法:通过脂质体lip-2000分别将NRP-1特异性siRNA、control siRNA转染入人胃腺癌AGS细胞株作为转染... 目的:探讨神经纤毛蛋白-1(neuropilin-1,NRP-1)的小干扰RNA(small interfering RNA,siRNA)对人胃腺癌细胞株AGS某些生物学行为的影响。方法:通过脂质体lip-2000分别将NRP-1特异性siRNA、control siRNA转染入人胃腺癌AGS细胞株作为转染组、无意义序列组,加入PBS的细胞作为空白对照组,采用MTT法检测三组细胞24h、48h、72h的增殖情况;Transwell小室侵袭和迁徙实验检测细胞的迁徙和侵袭能力。结果:转染后,转染组细胞的增殖能力在24h、48h和72h与对照组相比,均显著下降(P=0.00)。小室迁徙及侵袭实验表明:与对照组相比,转染组的胃癌AGS细胞迁徙能力显著下降,差异具有统计学意义(P<0.05)。转染组的胃癌AGS细胞侵袭能力显著下降,差异具有统计学意义(P<0.05)。结论:Neuropilin-1的siRNA能够明显影响人胃癌细胞株AGS的某些生物学行为。 展开更多
关键词 神经纤毛蛋白-1 人胃癌细胞株AGS siRNA 细胞增殖 Transwell小室实验
下载PDF
Investigation of a New Vortex-Induced Vibration Suppression Device in Laboratory Experiments 被引量:1
7
作者 ZHANG Yongbo GUO Haiyan +1 位作者 LIUXiaochun LI Xiaomin 《Journal of Ocean University of China》 SCIE CAS 2012年第2期129-136,共8页
In order to mitigate vortex-induced vibration (VIV) of marine risers, especially to eliminate the phenomenon of frequency 'lock-in', a new suppression device of crescent-shaped flow spoiler was designed with s... In order to mitigate vortex-induced vibration (VIV) of marine risers, especially to eliminate the phenomenon of frequency 'lock-in', a new suppression device of crescent-shaped flow spoiler was designed with seven different layout schemes. VIV model tests with six flow levels were conducted in a large wind-wave-current flume. In all cases, vibration responses in both in-line and cross-flow cases were measured. With the installation of suppression devices vibration frequency evolution of a riser was analyzed by Morlet wavelet transform. The principle of VIV suppression was interpreted through vibration characteristics. Fatigue life of the riser was calculated by the Palmgren-Miner rule. Compared with a bare riser, vibration of an outfitted riser with suppression devices disturbed the steady flow, the vibration amplitudes in the two flow directions were reduced, and the riser fatigue life was improved. 展开更多
关键词 vortex-induced vibration (VIV) suppression vibration wavelet transform fatigue life
下载PDF
Saline Stress Response of Plantlets of Common Wheat (Triticum aestivum) and Its Wild Congeners 被引量:1
8
作者 N. V. Terletskaya A. B. Rysbekova +2 位作者 A. B. Iskakova N. A. Khailenko F. A. Polimbetova 《Journal of Agricultural Science and Technology(B)》 2011年第2期198-204,共7页
The aim of this work was to study the reactions of wheat (T. aestivum L.) and its wild congeners under salt stress. Physiological mechanisms that underlie traits for salt tolerance plantlets have been used to test s... The aim of this work was to study the reactions of wheat (T. aestivum L.) and its wild congeners under salt stress. Physiological mechanisms that underlie traits for salt tolerance plantlets have been used to test some wheat species and to identify sources of salty tolerance. Stress conditions were founded by means of exposure of the plantlets in NaCI water solution, 1.68% that demonstrably differentiates the samples by growth parameters. Under laboratory conditions the ability of seedlings to bear a significant shortage of water, their ability to accumulate biomass, changing the parameters of linear growth processes and changes in water content in leaves and roots of seedlings under stress was determined. Interest is also the rate of growth of root fibrils in saline conditions. These experiments allowed to provide a comprehensive diagnosis of studied forms of wheat and make an initial opinion on their salt tolerance. Different features of abiotic stress responses of some wheat species at the early stages of development were shown that testifies necessi~ of great number of approaches at selection of genetic material for improvement of modern wheat eultivars. This work is the first phase of research for practical breeding. 展开更多
关键词 Saline stress response PLANTLETS T. aestivum L. wild congeners.
下载PDF
Effects of Organic Enrichment on Sandy Beach Meiofauna:A Laboratory Microcosm Experiment 被引量:2
9
作者 WANG Jianing ZHOU Hong ZHANG Zhinan CONG Bingqing XU Shuhui 《Journal of Ocean University of China》 SCIE CAS 2011年第3期246-254,共9页
Meiofauna samples from intertidal sediments of Qingdao No.2 Bathing Beach, China, were collected for field study, and subjected to organic enrichment in a laboratory microcosm experiment for 21 d. There were three dif... Meiofauna samples from intertidal sediments of Qingdao No.2 Bathing Beach, China, were collected for field study, and subjected to organic enrichment in a laboratory microcosm experiment for 21 d. There were three different treatments including non-organic addition as the control, low-organic enrichment (2 g DW green algae per 150 mL) and high-organic enrichment (10 g DW green algae per 150 mL). After 21 d, the meiofauna richness decreased in both organic enrichment treatments. Among the three treatments, total meiofauna abundance was significantly different, and the control groups had higher abundance than the other two treatment groups. However, the responses of the meiofauna abundance in the two organic enrichment treatments were non-significantly different. The relationship of meiofaunal abundance and nematode/copepod ratios to organic matter and oxygen level in the microcosm experiments were discussed. 展开更多
关键词 organic enrichment MEIOFAUNA NEMATODE ABUNDANCE microcosm experiment
下载PDF
Evaluation of mouse bioassay results in an inter-laboratory comparison for paralytic shellfish poisoning toxins 被引量:1
10
作者 曹际娟 郑江 +3 位作者 于兵 王秋艳 徐君怡 李爱峰 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2011年第4期912-916,共5页
An inter-laboratory comparison of the AOAC mouse bioassay for paralytic shellfish poisoning (PSP) toxicity in shellfish was carried out among 25 Chinese laboratories to examine the overall performance for PSP testing ... An inter-laboratory comparison of the AOAC mouse bioassay for paralytic shellfish poisoning (PSP) toxicity in shellfish was carried out among 25 Chinese laboratories to examine the overall performance for PSP testing in China, and to analyze the main factors affecting the performance of this method. The toxic scallop Patinopecten yessoensis collected from coast of Bohai Sea, China, was used as a test sample in the comparison study. The results were reported and evaluated using robust statistical methods. The z scores showed that 80%, 8%, and 12% of laboratories reported satisfactory results, unsatisfactory results, and questionable results, respectively. This evaluation demonstrates that the PSP mouse bioassay is an appropriate method for screening and testing PSP toxicity in shellfish. However, it was found that the experience and skill of technicians, as well as the body weight and health status of mice being used significantly affected the accuracy of the method. 展开更多
关键词 paralytic shellfish poisoning (PSP) mouse bioassay inter-laboratory comparison
下载PDF
Effect of floor level slit exhaust ventilation system on distribution of house dust 被引量:1
11
作者 吕阳 H.Yoshino +3 位作者 R.Takaki R.Kurihara A.Mochida H.Yonekura 《Journal of Central South University》 SCIE EI CAS 2012年第3期696-702,共7页
Based on the fact that the house dust usually falls on the ground, the floor level slit exhaust ventilation system including inlet located at the ceiling and outlet of slit exhaust installed at comer between wall and ... Based on the fact that the house dust usually falls on the ground, the floor level slit exhaust ventilation system including inlet located at the ceiling and outlet of slit exhaust installed at comer between wall and floor was considered. Experiments and simulations were performed to investigate the flow and diffusion fields that are affected by this floor level slit exhaust ventilation system. The characteristics of airflow with experiments and computation fluid dynamics (CFD) are generally similar except airflow at the location of impinging flow and the location right below the inlet. Riboflavin particles were used as the house dust. For the spatial distribution of riboflavin particles in the ventilation system before operation, due to the influence of gravity, different sizes of particles show smooth decay curve. After floor level slit exhaust ventilation system is operated, the decay rate of the particles becomes faster than that after the ventilation system is powered on, and the particles with diameter of 0.5-3.0 μm in the experimental data and calculated values show good agreement. 展开更多
关键词 house dust floor level slit exhaust riboflavin particles computational fluid dynamics
下载PDF
The Prosperity of Using Domestic Triticale Varieties in Kyrgyzstan
12
作者 Karabaev Aibek Nurudinovich 《Journal of Life Sciences》 2014年第3期290-293,共4页
The present researches mentioned questions of economic use of domestic triticale and their influences on a phytosanitory condition and fertility of an irrigated arable land in the Chuy Valley of Kyrgyzstan. The result... The present researches mentioned questions of economic use of domestic triticale and their influences on a phytosanitory condition and fertility of an irrigated arable land in the Chuy Valley of Kyrgyzstan. The result of the work consists of four tables, purpose of the work was to discover roots systems, nutrion value and the main laboratory testing of samples were conducted at the Humboldt University in Berlin, which was completed under the high and compliant standards of the world. The present research conducted on triticale varieties was firstly studied in Kyrgyzstan. 展开更多
关键词 TRITICALE soil CLIMATE procedure parameters.
下载PDF
Confidence Level Based on Ridge Estimator in Process Measurement and Its Application
13
作者 岳元龙 左信 罗雄麟 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第10期1144-1154,共11页
Ordinary least squares(OLS) algorithm is widely applied in process measurement, because the sensor model used to estimate unknown parameters can be approximated through multivariate linear model. However, with few or ... Ordinary least squares(OLS) algorithm is widely applied in process measurement, because the sensor model used to estimate unknown parameters can be approximated through multivariate linear model. However, with few or noisy data or multi-collinearity, unbiased OLS leads to large variance. Biased estimators, especially ridge estimator, have been introduced to improve OLS by trading bias for variance. Ridge estimator is feasible as an estimator with smaller variance. At the same confidence level, with additive noise as the normal random variable, the less variance one estimator has, the shorter the two-sided symmetric confidence interval is. However, this finding is limited to the unbiased estimator and few studies analyze and compare the confidence levels between ridge estimator and OLS. This paper derives the matrix of ridge parameters under necessary and sufficient conditions based on which ridge estimator is superior to OLS in terms of mean squares error matrix, rather than mean squares error.Then the confidence levels between ridge estimator and OLS are compared under the condition of OLS fixed symmetric confidence interval, rather than the criteria for evaluating the validity of different unbiased estimators. We conclude that the confidence level of ridge estimator can not be directly compared with that of OLS based on the criteria available for unbiased estimators, which is verified by a simulation and a laboratory scale experiment on a single parameter measurement. 展开更多
关键词 process measurement confidence level ridge estimator variance BIAS
下载PDF
Laboratory Evaluation of Biorational and Low Risk Insecticides and Their Mixtures for Management of Diamondback Moth Larvae
14
作者 Matthew Conklin Flanery Henry Ofosuhene Sintim Beatrice Nuck Dingha Louis Ernest Jackai 《Journal of Agricultural Science and Technology(A)》 2016年第2期77-91,共15页
The diamondback moth, Plutella xylostella L., has developed resistance to most insecticides used for its management. Suggested alternatives to forestall this process include biorational insecticides in mixtures with l... The diamondback moth, Plutella xylostella L., has developed resistance to most insecticides used for its management. Suggested alternatives to forestall this process include biorational insecticides in mixtures with low-risk insecticides. The aim of this study was to select an insecticide or insecticide mixture that could be adopted by small-scale growers for diamondback moth management. The effectiveness of four insecticide mixtures, i.e., Agroneem Plus (neem-derived), Spinosad (microbial origin), thiamethoxam (neonicotinoid) and a homemade methanol Jalapefio pepper extract, in laboratory bioassays was evaluated. Binary mixtures were tested against single products at manufacturer's label rates. These were applied to collard greens using the leaf dip method and fed to the newly molted 2nd or 3rd instar larvae. Mixtures were evaluated for efficacy based on larval mortality and consumption of leaf discs. The results showed interactions between Jalapefio pepper extract and Spinosad and between the neem-derived Agroneem Plus and thiamethoxam at some of the tested concentrations. Mixtures with at any amount of Spinosad killed all larvae. The neem-based product gave inconsistent results in some treatments; in some case, increased leaf damage did not result in commensurate larval mortalities. The reported resistance of diamondback moth larvae to Spinosad was not observed during this study, neither with Spinosad alone nor in mixtures. 展开更多
关键词 Agroneem diamondback moth management insecticide mixtures SPINOSAD thiamethoxam.
下载PDF
The Potentially Dangerous Asteroid (99942) Apophis
15
作者 Ireneusz Wlodarczyk 《Journal of Earth Science and Engineering》 2014年第6期385-388,共4页
This paper computed the newest impact solutions of the potentially dangerous asteroid (99942) Apophis based on 4,138 optical observations from March 15.10789 UTC (Universal Time Coordinated), 2004 to February 28.0... This paper computed the newest impact solutions of the potentially dangerous asteroid (99942) Apophis based on 4,138 optical observations from March 15.10789 UTC (Universal Time Coordinated), 2004 to February 28.089569 UTC, 2014 and 20 radar observations from January 27, 2005 through March 15, 2013, as of June 20, 2014. Using the freely available the OrbFit software Package, this paper followed its orbit forward in the searching for close approaches with the Earth and possible impacts up to year 2116. With the different A2 non-gravitational parameter in the motion of the asteroid (99942) Apophis, this paper computed possible impact solutions using the JPL DE405 (Jet Propulsion Laboratory Development Ephemeris) and 25 additional massive perturbed asteroids. Additionally, this paper used weighing and selection methods adopted in the OrbFit software as prepared by the NEODyS (Near Earth Objects--Dynamical Side) Team. Moreover, this paper used method of computing the orbit of Apophis taking into account star catalog debiasing and an error model with assumed astrometric errors RMS (root mean square), deduced from the observational material of the given observatories. JPL's Sentry and NEODyS's CLOMMON2, two automatic monitoring systems routinely scanning for possible impacts in the next hundred years. Only for several dangerous asteroids presented results are computed with the non-gravitational parameters. This paper detected possible impacts of the asteroid (99942) Apophis only with the non-gravitational parameter, A2 〉 0. It was appeared that impacts in 2068, 2087, 2105 and in 2111 were possible only when Apophis rotated in prograde direction. 展开更多
关键词 ASTROMETRY minor planets individual asteroids Apophis (99942).
下载PDF
Multiple Excitation Wavelength Fluorescence Emission Spectra Technique for Discrimination of Phytoplankton
16
作者 HU Xupeng SU Rongguo +3 位作者 ZHANG Fang WANG Xiulin WANG Hongtao ZHENG Zhixi 《Journal of Ocean University of China》 SCIE CAS 2010年第1期16-24,共9页
In vivo fluorescence methods are efficient tools for studying the distribution of phytoplankton in nature.Different algae species usually have different pigments with different ratios,which results in different fluore... In vivo fluorescence methods are efficient tools for studying the distribution of phytoplankton in nature.Different algae species usually have different pigments with different ratios,which results in different fluorescence emission spectra.Based on multiple excitation wavelength fluorescence emission spectra,a discrimination technique is established in this study.The discrimination method,established by multivariate linear regression and weighted least-squares,was used to differentiate the samples cultured in the laboratory and collected from Jiaozhou Bay near Qingdao at the division level.The correctly discriminated samples were ≥ 86% for single algae samples,≥ 88% for simulatively mixed ones,≥ 91% for physically mixed ones and 100% for samples collected from Jiaozhou Bay.The result in this research is more definite for the physically mixed samples in the laboratory.The method described here can be employed to monitor the phytoplankton population in the marine environment. 展开更多
关键词 weighted least squares fluorescence emission spectrum PHYTOPLANKTON
下载PDF
SSUH model: A small-strain extension of the unified hardening model 被引量:4
17
作者 YAO YangPing QU Shan +1 位作者 YIN ZhenYu ZHU EnYang 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2016年第2期225-240,共16页
A small strain unified hardening(SSUH) model is proposed in the present study to tackle the small strain behavior of clay. The model is an extension of the unified hardening(UH) model for overconsolidated(OC) clays ac... A small strain unified hardening(SSUH) model is proposed in the present study to tackle the small strain behavior of clay. The model is an extension of the unified hardening(UH) model for overconsolidated(OC) clays accounting for the small strain stiffness. The new features of the SSUH model over the UH model include:(a) a new elastic hysteretic stress-strain relationship to evaluate the stiffness degradation at small strains and to generate the hysteresis loop under cyclic loading condition;(b) a revised unified hardening parameter to enhance the plastic stiffness at small strains; and(c) a new overconsolidation parameter, which is crucial to make the UH model working with the elastic hysteretic stress-strain relationship effectively. With these enhancements, the SSUH model can describe a high initial stiffness and the highly nonlinear stress-strain relationship at small strains, in addition to the shear dilatancy and strain hardening/softening behaviors of OC clays at large strains. In comparison with the Modified Cam-clay(MCC) model, the proposed model needs two more small strain related parameters, which can be easily obtained from laboratory tests. Finally, some drained triaxial compression tests at large strains, drained triaxial compression/extension tests at small strains, an undrained compression test at small strains and a drained cyclic constant radial stress test are employed to validate the new model. 展开更多
关键词 small strain overconsolidated clays constitutive model stiffness degradation NONLINEARITY
原文传递
Design and optimization of a trajectory for Moon departure Near Earth Asteroid exploration 被引量:7
18
作者 CHEN Yang BAOYIN HeXi LI JunFeng 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2011年第4期748-755,共8页
The lunar probe often has some remaining fuel on completing the predefined Moon exploration mission and may carry out some additional tasks from the Moon orbit using the fuel.The possibility for the lunar probe to esc... The lunar probe often has some remaining fuel on completing the predefined Moon exploration mission and may carry out some additional tasks from the Moon orbit using the fuel.The possibility for the lunar probe to escape from the Moon and the Earth is analyzed.Design and optimization of the trajectory from the Moon orbit to the Near Earth Asteroids (NEAs) using the spacecraft's residual fuel is studied.At first,the semi-major axis,inclinations and the phase relations with the Earth of all the numbered NEAs are investigated to preliminarily select the possible targets.Based on the Sun-centered two-body problem,the launch window and the asteroid candidates are determined by calculating the minimum delta-v for two-impulse rendezvous mission and one-impulse flyby mission,respectively.For a precise designed trajectory,a full ephemeris dynamical model,which includes gravities of the Sun,the planets and the Moon,is adopted by reading the JPL ephemeris.The departure time,arrival time,burning time duration and thrust angles are set as variables to be designed and optimized.The optimization problem is solved via the Particle Swarm Optimization (PSO) algorithm.Moreover,two feasible NEA flyby missions are presented. 展开更多
关键词 trajectory design full ephemeris model Near Earth Asteroid exploration Particle Swarm Optimization
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部