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Post Thyroidectomy Assessment of Intact Parathyroid Hormone for Early Prediction of Hypocalcaemia
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作者 Md. Masum Billah Ripon Kumar Sarkar +6 位作者 Md. Yousuf Ali Saad Zaman Md. Nazmul Hasan Md. Shehab Uddin Md. Mosleh Uddin Kazi Shameemus Salam Farzana Binte Abedin Leera 《International Journal of Otolaryngology and Head & Neck Surgery》 2024年第2期71-84,共14页
Background: As the half-life of intact parathyroid hormone (iPTH) is very low, it reflects parathyroid insufficiency within minutes to hours after total thyroidectomy. Therefore, iPTH level assessment in the postopera... Background: As the half-life of intact parathyroid hormone (iPTH) is very low, it reflects parathyroid insufficiency within minutes to hours after total thyroidectomy. Therefore, iPTH level assessment in the postoperative period can be used to predict the development of hypocalcaemia. The optimal time point to measure serum iPTH is important for the accurate prediction of hypocalcaemia. Aim: This paper aims to evaluate the ability of iPTH as an early predictive marker of hypocalcaemia and determine which time iPTH is more able to predict postoperative hypocalcaemia. Method: This prospective observational study was conducted in the Department of Otolaryngology-Head & Neck Surgery, BSMMU, Dhaka, from July 2020 to December 2021, with 67 patients who underwent total thyroidectomy. iPTH levels were measured on the day before the operation and at 1 hour, 4 hours, and 24 hours after the operation. S.calcium levels were measured on the day before the operation and 1<sup>st</sup> postoperative day. All the data were compiled and sorted properly and were analyzed statistically. Results: Postoperative hypocalcaemia developed in 18 cases, with an incidence of 26.9%. Pearson correlation showed a significant correlation between postoperative iPTH at 1 hr, 4 h, and 24 hr with 1st postoperative calcium value. The Receiver operating characteristic (ROC) curve was processed for the postoperative iPTH at 1 hr, 4 h, and 24 hr. The sensitivity, specificity, cut-off value, and mean AUC found 93.9%, 94.4%, ≤14.0, 0.988;95.9%, 94.4%, ≤09.5, 0.993 and 91.8%, 94.4%, ≤11.0, 0.993 respectively. Conclusion: iPTH can be used as an early predictor of post-thy-roidectomy hypocalcaemia. 4 hr iPTH showed more sensitivity and specificity for a cut-off value near the laboratory reference range. 展开更多
关键词 Total Thyroidectomy HYPOCALCAEMIA Serum intact Parathyroid Hormone Early Predictor of Hypocalcaemia
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Three independent parameters to describe conventional triaxial compressive strength of intact rocks 被引量:11
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作者 Mingqing You 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2010年第4期350-356,共7页
The strengths of 12 rocks cited from literatures increase in a nonlinear way with increasing confining pressure against the Coulomb criterion. The criteria with power forms like the generalized Hoek-Brown criterion ar... The strengths of 12 rocks cited from literatures increase in a nonlinear way with increasing confining pressure against the Coulomb criterion. The criteria with power forms like the generalized Hoek-Brown criterion are not available for describing the strength properties in the whole test range for Indiana limestone, Yamaguchi marble and Vosges sandstone, of which the differential stresses are approximately constant at high confining pressures. The exponential criterion with three parameters fits the test data of those 12 rocks well with a low misfit. The three parameters are independent of the uniaxial compressive strength (UCS), the initial increasing rate of strength with confining pressure, and the limitation of differential stress. 展开更多
关键词 strength criteria criterion parameters exponential criterion intact rocks
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Bayesian data analysis to quantify the uncertainty of intact rock strength 被引量:8
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作者 Luis Fernando Contreras Edwin T.Brown Marc Ruest 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2018年第1期11-31,共21页
One of the main difficulties in the geotechnical design process lies in dealing with uncertainty. Uncertainty is associated with natural variation of properties, and the imprecision and unpredictability caused by insu... One of the main difficulties in the geotechnical design process lies in dealing with uncertainty. Uncertainty is associated with natural variation of properties, and the imprecision and unpredictability caused by insufficient information on parameters or models. Probabilistic methods are normally used to quantify uncertainty. However, the frequentist approach commonly used for this purpose has some drawbacks.First, it lacks a formal framework for incorporating knowledge not represented by data. Second, it has limitations in providing a proper measure of the confidence of parameters inferred from data. The Bayesian approach offers a better framework for treating uncertainty in geotechnical design. The advantages of the Bayesian approach for uncertainty quantification are highlighted in this paper with the Bayesian regression analysis of laboratory test data to infer the intact rock strength parameters σand mused in the Hoek-Brown strength criterion. Two case examples are used to illustrate different aspects of the Bayesian methodology and to contrast the approach with a frequentist approach represented by the nonlinear least squares(NLLS) method. The paper discusses the use of a Student’s t-distribution versus a normal distribution to handle outliers, the consideration of absolute versus relative residuals, and the comparison of quality of fitting results based on standard errors and Bayes factors. Uncertainty quantification with confidence and prediction intervals of the frequentist approach is compared with that based on scatter plots and bands of fitted envelopes of the Bayesian approach. Finally, the Bayesian method is extended to consider two improvements of the fitting analysis. The first is the case in which the Hoek-Brown parameter, a, is treated as a variable to improve the fitting in the triaxial region. The second is the incorporation of the uncertainty in the estimation of the direct tensile strength from Brazilian test results within the overall evaluation of the intact rock strength. 展开更多
关键词 UNCERTAINTY intact rock strength Bayesian analysis Hoek-Brown criterion
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Gas desorption characteristics of the high-rank intact coal and fractured coal 被引量:15
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作者 Lu Shouqing Cheng Yuanping +3 位作者 Qin Liming Li Wei Zhou Hongxing Guo Haijun 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2015年第5期819-825,共7页
The objective of this work is to study the gas desorption characteristics of the high-rank intact coal and fractured coal.The gas adsorption,mercury porosimetry and gas desorption experiments were carried out in this ... The objective of this work is to study the gas desorption characteristics of the high-rank intact coal and fractured coal.The gas adsorption,mercury porosimetry and gas desorption experiments were carried out in this study.Then,the theories of thermodynamics,diffusion mechanism and desorption kinetics were used to estimate the gas desorption characteristics.The results of gas adsorption experiments show that the initial isosteric adsorption heat of the intact coal is greater than that of the fractured coal,indicating that the gas molecules desorb more easily from fractured coal than intact coal.Using the mercury porosimetry,we find that the diffusion channels of fractured coal are more developed than those of intact coal.The difficult diffusion form dominates in the intact coal during the gas diffusing,while the easy diffusion form dominates in the fractured coal.The results of gas desorption experiments show that the initial gas desorption volume and velocity of the fractured coal are both greater than those of the intact coal.Using the Fick diffusion law,the study calculates the gas diffusion coefficients of the intact coal and fractured coal.The diffusion coefficients of the fractured coal are 2 times and 10 times greater than those of the intact coal at the time of 0-120 and 0-10 min,respectively. 展开更多
关键词 intact coal Fractured coal Isosteric adsorption heat Diffusion coefficient
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An approximate nonlinear modified Mohr-Coulomb shear strength criterion with critical state for intact rocks 被引量:7
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作者 Baotang Shen Jingyu Shi Nick Barton 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2018年第4期645-652,共8页
In this paper, the Mohr-Coulomb shear strength criterion is modified by mobilising the cohesion and internal friction angle with normal stress, in order to capture the nonlinearity and critical state concept for intac... In this paper, the Mohr-Coulomb shear strength criterion is modified by mobilising the cohesion and internal friction angle with normal stress, in order to capture the nonlinearity and critical state concept for intact rocks reported in the literature. The mathematical expression for the strength is the same as the classical form, but the terms of cohesion and internal friction angle depend on the normal stress now,leading to a nonlinear relationship between the strength and normal stress. It covers both the tension and compression regions with different expressions for cohesion and internal friction angle. The strengths from the two regions join continuously at the transition of zero normal stress. The part in the compression region approximately satisfies the conditions of critical state, where the maximum shear strength is reached. Due to the nonlinearity, the classical simple relationship between the parameters of cohesion, internal friction angle and uniaxial compressive strength from the linear Mohr-Coulomb criterion does not hold anymore. The equation for determining one of the three parameters in terms of the other two is supplied. This equation is nonlinear and thus a nonlinear equation solver is needed. For simplicity, the classical linear relationship is used as a local approximation. The approximate modified Mohr-Coulomb criterion has been implemented in a fracture mechanics based numerical code FRACOD,and an example case of deep tunnel failure is presented to demonstrate the difference between the original and modified Mohr-Coulomb criteria. It is shown that the nonlinear modified Mohr-Coulomb criterion predicts somewhat deeper and more intensive fracturing regions in the surrounding rock mass than the original linear Mohr-Coulomb criterion. A more comprehensive piecewise nonlinear shear strength criterion is also included in Appendix B for those readers who are interested. It covers the tensile, compressive, brittle-ductile behaviour transition and the critical state, and gives smooth transitions. 展开更多
关键词 Shear strength Modified Mohr-Coulomb criterion Critical state intact rock
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Application Fourier transform near infrared spectrometer in rapid estimation of soluble solids content of intact citrus fruits 被引量:5
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作者 LU Hui-shan XU Hui-rong YING Yi-bin FU Xia-ping YU Hai-yan TIAN Hai-qing 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2006年第10期794-799,共6页
Nondestructive method of measuring soluble solids content (SSC) of citrus fruits was developed using Fourier transform near infrared reflectance (FT-NIR) measurements collected through optics fiber. The models describ... Nondestructive method of measuring soluble solids content (SSC) of citrus fruits was developed using Fourier transform near infrared reflectance (FT-NIR) measurements collected through optics fiber. The models describing the relationship between SSC and the NIR spectra of citrus fruits were developed and evaluated. Different spectra correction algorithms (standard normal variate (SNV), multiplicative signal correction (MSC)) were used in this study. The relationship between laboratory SSC and FT-NIR spectra of citrus fruits was analyzed via principle component regression (PCR) and partial least squares (PLS) re- gression method. Models based on the different spectral ranges were compared in this research. The first derivative and second derivative were applied to all spectra to reduce the effects of sample size, light scattering, instrument noise, etc. Different baseline correction methods were applied to improve the spectral data quality. Among them the second derivative method after baseline correction produced best noise removing capability and yielded optimal calibration models. A total of 170 NIR spectra were acquired; 135 NIR spectra were used to develop the calibration model; the remaining spectra were used to validate the model. The developed PLS model describing the relationship between SSC and NIR reflectance spectra could predict SSC of 35 samples with correlation coefficient of 0.995 and RMSEP of 0.79 °Brix. 展开更多
关键词 FT-NIR spectroscopy Soluble solids content intact citrus Partial least squares analysis Reflectance mode
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Energy-limiting factor for coal and gas outburst occurrence in intact coal seam 被引量:3
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作者 Qingyi Tu Yuanping Cheng +2 位作者 Sheng Xue Ting Ren Xiang Cheng 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2021年第4期729-742,共14页
This research reviewed the mechanics and gas desorption properties of intact coal,and tested the crushing work ratios of different intact coals,and then,studied the stress conditions for the failure or crushing of int... This research reviewed the mechanics and gas desorption properties of intact coal,and tested the crushing work ratios of different intact coals,and then,studied the stress conditions for the failure or crushing of intact coal and the gas demand for the pulverization of intact coal particles.When a real-life outburst case is examined,the required minimum stress for intact coal outburst is estimated.The study concludes that the crushing work ratios of three intact coal samples vary from 294.3732 to 945.8048 J/m^(2).For the real-life case,more than 2300 MJ of transport work is needed,and 10062.09,7046.57 and 5895.47 m^(3) of gas is required when the gas pressure is 1,2 and 3 MPa,respectively.The crushing work exceeds the transport work and even reaches 13.96 times of the transport work.How to provide such an enormous crushing work is an energy-limiting factor for the outburst in intact coal.The strain energy is needed for the crushing work,and the required minimum stress is over 54.35 MPa,even reaching 300.44 MPa.These minimum stresses far exceed the in-situ vertical and horizontal stresses that can be provided at the 300–700 m mining depth range. 展开更多
关键词 Coal and gas outburst intact coal Crushing work ratio Geological factors Outburst energy
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High-efficiency somatic reprogramming induced by intact MII oocytes 被引量:2
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作者 Hui Yang Linyu Shi Shenghua Zhang Jiangwei Lin Jing Jiang Jinsong Li 《Cell Research》 SCIE CAS CSCD 2010年第9期1034-1042,共9页
Somatic nuclei can be reprogrammed into a pluripotent state by nuclear transfer, cell fusion and expression of transcription factors. However, these reprogramming processes are very inefficient, which has greatly hind... Somatic nuclei can be reprogrammed into a pluripotent state by nuclear transfer, cell fusion and expression of transcription factors. However, these reprogramming processes are very inefficient, which has greatly hindered efforts to elucidate the underlying molecular mechanisms. Here, we report a new reprogramming strategy that combines the advantages of all three reprogramming methodologies into one process. We injected nuclei from cumulus cells into intact MII oocytes. Following activation, 80% of the reconstructed embryos developed to the blastocyst stage, and tetraploid (4N) embryonic stem (ES) cell lines were generated at a rate of 30% per reconstructed oocyte. We also generated triploid (3N) ES cells after injection of somatic nuclei into activated oocytes. 4N and 3N ES cells expressed pluripotent markers and differentiated into cell types of three embryonic germ layers in vivo. Moreover, all ES cells generated histocompatible, differentiated cells after being engrafted in immunocompetent B6D2F1 mice, showing that ES cells derived from this reprogramming strategy might serve as a source of genetically tailored tissues for transplantation. Thus, we have established a simple and highly efficient reprogramming procedure that provides a system for investigating the molecular mechanisms involved in somatic reprogramming. 展开更多
关键词 somatic reprogramming nuclear transfer intact oocytes embryonic stem cell TETRAPLOID
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Feasibility study on the use of near-infrared spectroscopy for rapid and nondestructive determination of gossypol content in intact cottonseeds 被引量:5
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作者 LI Cheng SU Bangsong +3 位作者 ZHAO Tianlun LI Cong CHEN Jinhong ZHU Shuijin 《Journal of Cotton Research》 2021年第2期138-146,共9页
Background:Gossypol found in cottonseeds is toxic to human beings and monogastric animals and is a primary parameter for the integrated utilization of cottonseed products.It is usually determined by the techniques rel... Background:Gossypol found in cottonseeds is toxic to human beings and monogastric animals and is a primary parameter for the integrated utilization of cottonseed products.It is usually determined by the techniques relied on complex pretreatment procedures and the samples after determination cannot be used in the breeding program,so it is of great importance to predict the gossypol content in cottonseeds rapidly and nondestructively to substitute the traditional analytical method.Results:Gossypol content in cottonseeds was investigated by near-infrared spectroscopy(NIRS)and high-performance liquid chromatography(HPLC).Partial least squares regression,combined with spectral pretreatment methods including Savitzky-Golay smoothing,standard normal variate,multiplicative scatter correction,and first derivate were tested for optimizing the calibration models.NIRS technique was efficient in predicting gossypol content in intact cottonseeds,as revealed by the root-mean-square error of cross-validation(RMSECV),root-mean-square error of prediction(RMSEP),coefficient for determination of prediction(R_(p)^(2)),and residual predictive deviation(RPD)values for all models,being 0.05∼0.07,0.04∼0.06,0.82∼0.92,and 2.3∼3.4,respectively.The optimized model pretreated by Savitzky-Golay smoothing+standard normal variate+first derivate resulted in a good determination of gossypol content in intact cottonseeds.Conclusions:Near-infrared spectroscopy coupled with different spectral pretreatments and partial least squares(PLS)regression has exhibited the feasibility in predicting gossypol content in intact cottonseeds,rapidly and non destructively.It could be used as an alternative method to substitute for traditional one to determi ne the gossypol content in intact cottonseeds. 展开更多
关键词 intact cottonseed CHEMOMETRICS GOSSYPOL Near-infrared spectroscopy
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Robotic Knee Tracking Control to Mimic the Intact Human Knee Profile Based on Actor-Critic Reinforcement Learning 被引量:2
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作者 Ruofan Wu Zhikai Yao +1 位作者 Jennie Si He(Helen)Huang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2022年第1期19-30,共12页
We address a state-of-the-art reinforcement learning(RL)control approach to automatically configure robotic pros-thesis impedance parameters to enable end-to-end,continuous locomotion intended for transfemoral amputee... We address a state-of-the-art reinforcement learning(RL)control approach to automatically configure robotic pros-thesis impedance parameters to enable end-to-end,continuous locomotion intended for transfemoral amputee subjects.Specifically,our actor-critic based RL provides tracking control of a robotic knee prosthesis to mimic the intact knee profile.This is a significant advance from our previous RL based automatic tuning of prosthesis control parameters which have centered on regulation control with a designer prescribed robotic knee profile as the target.In addition to presenting the tracking control algorithm based on direct heuristic dynamic programming(dHDP),we provide a control performance guarantee including the case of constrained inputs.We show that our proposed tracking control possesses several important properties,such as weight convergence of the learning networks,Bellman(sub)optimality of the cost-to-go value function and control input,and practical stability of the human-robot system.We further provide a systematic simulation of the proposed tracking control using a realistic human-robot system simulator,the OpenSim,to emulate how the dHDP enables level ground walking,walking on different terrains and at different paces.These results show that our proposed dHDP based tracking control is not only theoretically suitable,but also practically useful. 展开更多
关键词 Automatic tracking of intact knee configuration of robotic knee prosthesis direct heuristic dynamic programming(dHDP) reinforcement learning control
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A RBPF Algorithm with Non-intact Particle Data for FastSLAM 被引量:2
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作者 Weinan Chen Yisheng Guan +1 位作者 Hong Zhang Lei Zhu 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2018年第5期70-77,共8页
RBPF( Rao-Blackwellized Particle Filter) is a popular PF( Particle Filter) in decreasing the dimension of estimation problems and FastSLAM( Fast Simultaneous Localization and Mapping) is a RBPFbased algorithm. In Fast... RBPF( Rao-Blackwellized Particle Filter) is a popular PF( Particle Filter) in decreasing the dimension of estimation problems and FastSLAM( Fast Simultaneous Localization and Mapping) is a RBPFbased algorithm. In FastSLAM,each particle carries a large amount of data which results in low computing efficiency and large memory space occupancy. To solve this problem,a RBPF algorithm with non-intact particle data is studied. The key idea is to differentiate the particle data. Through the screening of particles,the number of particles carrying individual map data is limited to reduce the data occupied space and speed up the computational efficiency. The simulation and experiment results have verified the effectiveness and accuracy of the algorithm. Compared with the original one,this proposed algorithm reduces time consumption by 18%-34% and considerably saves memory space. 展开更多
关键词 RBPF non-intact PARTICLE DATA SLAM
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Optimized Mamdani fuzzy models for predicting the strength of intactrocks and anisotropic rock masses 被引量:1
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作者 Mojtaba Asadi 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2016年第2期218-224,共7页
Development of accurate and reliable models for predicting the strength of rocks and rock masses is one of the most common interests of geologists,civil and mining engineers and many others.Due to uncertainties in eva... Development of accurate and reliable models for predicting the strength of rocks and rock masses is one of the most common interests of geologists,civil and mining engineers and many others.Due to uncertainties in evaluation of effective parameters and also complicated nature of geological materials,it is difficult to estimate the strength precisely using theoretical approaches.On the other hand,intelligent approaches have attracted much attention as novel and effective tools of solving complicated problems in engineering practice over the past decades.In this paper,a new method is proposed for mining descriptive Mamdani fuzzy inference systems to predict the strength of intact rocks and anisotropic rock masses containing well-defined through-going joint.The proposed method initially employs a genetic algorithm(GA)to pick important rules from a preliminary rule base produced by grid partitioning and,subsequently,selected rules are given weights using the GA.Moreover,an information criterion is used during the first phase to optimize the models in terms of accuracy and complexity.The proposed hybrid method can be considered as a robust optimization task which produces promising results compared with previous approaches. 展开更多
关键词 intact rock Anisotropic jointed roc Mamdani fuzzy system Genetic algorithm(GA) Information criteria
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Valvuloplasty of fetal pulmonary atresia with intact ventricular septum and hypoplastic right heart: Mid-term follow-up results 被引量:3
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作者 Gang Luo Shuai Gao +4 位作者 Hongxiao Sun Zhixian Ji Dunliang Wang Yue Sun Silin Pan 《Journal of Interventional Medicine》 2022年第4期196-199,共4页
Objective:This study aimed to analyze and evaluate the results of mid-term follow-up after fetal pulmonary valvuloplasty(FPV)in fetuses with pulmonary atresia with intact ventricular septum(PA/IVS).Methods:From August... Objective:This study aimed to analyze and evaluate the results of mid-term follow-up after fetal pulmonary valvuloplasty(FPV)in fetuses with pulmonary atresia with intact ventricular septum(PA/IVS).Methods:From August 31,2018,to May 31,2019,seven fetuses with PA/IVS and hypoplastic right heart were included in this study.All underwent echocardiography by the same specialist and were operated on by the same team.Intervention and echocardiography data were collected,and changes in the associated indices noted during follow-up were analyzed.Results:All seven fetuses successfully underwent FPV.The median gestational age at FPV was 27.54 weeks.The average FPV procedural time was 6 min.Persistent bradycardia requiring treatment occurred in 4/7 procedures.Finally,five pregnancies were successfully delivered,and the other two were aborted.Compared to data before fetal cardiac interventions(FCI),tricuspid valve annulus diameter/mitral valve annulus diameter(TV/MV)and right ventricle diameter/left ventricle diameter(RV/LV)of all fetuses had progressively improved.The maximum tricuspid regurgitation velocity decreased from 4.60 m/s to 3.64 m/s.The average follow-up time was 30.40±2.05 months.During the follow-up period,the diameter of the tricuspid valve ring in five children continued to improve,and the development rate of the tricuspid valve was relatively obvious from 6 months to 1 year after birth.However,the development of the right ventricle after birth was relatively slow.It was discovered that there were individual variations in the development of the right ventricle during follow-up.Conclusion:The findings support the potential for the development of the right ventricle and tricuspid valve in fetuses with PA/IVS who underwent FCI.Development of the right ventricle and tricuspid valve does not occur synchronously during pregnancy.The right ventricle develops rapidly in utero,but the development of tricuspid valve is more apparent after birth than in utero. 展开更多
关键词 Congenital heart disease fetal cardiac intervention fetal pulmonary valvuloplasty hypoplastic right heart syndrome pulmonary atresia with intact septum
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Humidification vibration deformation behavior of intact loess 被引量:1
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作者 CHENG Da-wei LUO Ya-sheng +2 位作者 WU Cai-ping CHEN Xi GUO Hong 《Journal of Central South University》 SCIE EI CAS 2013年第7期1985-1991,共7页
A parameter, known as the parameter of humidification vibration deformation, was proposed, describing quantitatively the impact of water content on vibration settlement deformation, and its relationship with humidific... A parameter, known as the parameter of humidification vibration deformation, was proposed, describing quantitatively the impact of water content on vibration settlement deformation, and its relationship with humidification water content, dynamic shear stress peak value, initial consolidation stress and vibration frequency was built. The result shows that 1) the parameter of humidification vibration deformation increases with the vibration shear stress peak value increasing. 2) The humidification water content has significant influence on the curve of the parameter of humidification vibration deformation and the peak vibration shear stress. When the humidification water content is low, the curve increases slowly. However, when the humidification water content is high, the curve increases rapidly. 3) Initial consolidation stress has significant influence on the humidification vibration deformation coefficient. When initial consolidation stress is not large enough to destroy the loess structure, with initial consolidation stress increasing, the humidification vibration deformation coefficient decreases. On the contrary, the humidification vibration deformation coefficient increases with initial consolidation stress increasing. 4) With the increase of vibration time, the parameter of humidification vibration settlement shows an increasing trend overall. The initial dynamic shear stress peak value and humidification water content all have significant effects on the curve of the parameter of humidification vibration settlement and vibration time. However, the humidification water content is even more significant. 展开更多
关键词 intact loess vibration deformation humidification vibration deformation coefficient
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Intact soft clay’s critical response to dynamic stress paths on different combinations of principal stress orientation
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作者 沈扬 周建 +1 位作者 龚晓南 刘汉龙 《Journal of Central South University》 SCIE EI CAS 2008年第S2期147-154,共8页
Comprehensive tests on Hangzhou intact soft clay were performed, which were used to obtain the soils' critical response to undrained dynamic stress paths under different combinations of principal stress orientatio... Comprehensive tests on Hangzhou intact soft clay were performed, which were used to obtain the soils' critical response to undrained dynamic stress paths under different combinations of principal stress orientation. The different combinations included cyclic principal stress rotation (CPSR for short), cyclic shear with abrupt change of principal stress orientation (CAPSO for short) and cyclic shear with fixed principal stress orientation (CFPSO for short). On one side, under all these stress paths, samples have obvious strain inflection points and shear bands, and the excess pore water pressure is far from the level of initial effective confining pressure at failure. Stress paths of major principal stress orientation (α) alternating from negative and positive have quite different influence on soil's properties with those in which α is kept negative or positive. On the other side, due to the soil's strongly initial anisotropy, samples under double-amplitudes CPSR and CAPSO (or single-amplitude CPSR and CFPSO) have similar properties on dynamic shear strength and pore water pressure development tendency when α is kept within ±45°, while have quite different properties when α oversteps ±45°. 展开更多
关键词 cyclic principal STRESS rotation ABRUPT change of principal STRESS ORIENTATION fixed principal STRESS ORIENTATION intact soft clay torsional shear strain EXCESS pore water pressure
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KGmax Curves Associated With Second Generation Intact Stability Criteria for Different Types of Ships
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作者 Francois Grinnaert Jean-Yves Billard Jean-Marc Laurens 《Journal of Marine Science and Application》 CSCD 2016年第3期223-235,共13页
Currently, second generation intact stability criteria are being developed and evaluated by the International Maritime Organization(IMO). In this paper, we briefly present levels 1 and 2 assessment methods for the cri... Currently, second generation intact stability criteria are being developed and evaluated by the International Maritime Organization(IMO). In this paper, we briefly present levels 1 and 2 assessment methods for the criteria of pure loss of stability and parametric roll failure modes. Subsequently, we show the KG_(max) curves associated with these criteria. We compute these curves for five different types of ships and compare them with the curves embodied in the current regulations. The results show that the safety margin ensured by the first level-1 method of calculation for both pure loss of stability and parametric roll seems to be excessive in many cases. They also show that the KG_(max) given by the second level-1 method and by the level-2 method may be very similar. In some cases, the level-2 method can be more conservative than the second level-1 method, which is unanticipated by the future regulation. The KG_(max) curves associated with parametric roll confirm that the C11 container ship is vulnerable to this failure mode. The computation of the second check coefficient of parametric roll level 2(C2) for all possible values of KG reveals the existence of both authorized and restricted areas on the surface formed by both the draft and KG, which may replace the classical KG_(max) curves. In consequence, it is not sufficient to check that C2 is lower than the maximum authorized value(R_(PR0)) for a fixed ship's loading condition. 展开更多
关键词 pure loss of stability parametric roll KGmax curve second generation intact stability criteria
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Boron and Zinc Transport Through Intact Columns of Calcareous Soils
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作者 M. MAHMOOD-UL-HASSAN M. S. AKHTAR G. NABI 《Pedosphere》 SCIE CAS CSCD 2008年第4期524-532,共9页
Leaching of boron (B) and zinc (Zn) can be significant in some pedomorphic conditions, which can cause contamination of shallow groundwater and economic losses. Boron and Zn adsorption and transport was studied us... Leaching of boron (B) and zinc (Zn) can be significant in some pedomorphic conditions, which can cause contamination of shallow groundwater and economic losses. Boron and Zn adsorption and transport was studied using 8.4 cm diameter × 28 cm long intact columns from two calcareous soil series with differing clay contents and vadose zone structures: Lyallpur soil series, clay loam (fine-silty, mixed, hyperthermic Ustalfic Haplargid), and Sultanpur soil series, sandy loam (coarse-silty, mixed, hyperthermic Ustollic Camborthid). The adsorption isotherms were developed by equilibrating soil with 0.01 tool L^-1 CaCl2 aqueous solution containing varying amounts of B and Zn and were fitted to the Langmuir equation. The B and Zn breakthrough curves were fitted to the two-domain convective-dispersive equation. At the end of the leaching experiment, 0.11 L 10 g L^-1 blue dye solution was also applied to each column to mark the flow paths. The Lyallpur soil columns had a slightly greater adsorption partition coefficient both for B and Zn than the Sultanpur soil columns. In the Lyallpur soil columns, B arrival was immediate but the peak concentration ratio (the concentration in solution at equilibrium/concentration applied) was lower than that in the Sultanpur soil columns. The breakthrough of B in the Sultanpur soil columns occurred after about 10 cm of cumulative drainage in both the columns; the rise in effluent concentration was fast and the peak concentration ratio was almost 1. Zinc leaching through the soil columns was very limited as only one column from the Lyallpur soil series showed Zn breakthrough in the effluent where the peak concentration ratio was only 0.05. This study demonstrates the effect of soil structure on B transport and has implications for the nutrient management in field soils. 展开更多
关键词 adsorption isotherm BORON intact soil column transport parameters ZINC
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Evolution of macro-meso properties of intact loess under long-term seepage and its influence on irrigation-induced loess flowslides
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作者 JIAN Tao KONG Ling-wei +2 位作者 BAI Wei LIU Bing-heng SUN Zhi-liang 《Journal of Mountain Science》 SCIE CSCD 2022年第10期2935-2951,共17页
The loess tableland provides an excellent site for people to live and cultivate.However,flowslides occur frequently on the slope of loess tablelands due to agriculture irrigation,resulting in serious economic losses a... The loess tableland provides an excellent site for people to live and cultivate.However,flowslides occur frequently on the slope of loess tablelands due to agriculture irrigation,resulting in serious economic losses and casualties.The structure degradation effect of irrigation water seepage on intact loess leads to a weakening of its mechanical properties,which may be responsible for the recurrent occurrence of flowslides in irrigated loess tablelands.In this paper,seepage tests and triaxial tests were carried out to investigate the evolution of the microstructure and undrained shear properties of intact loess during seepage.The results show that water seepage leads to a significant decrease in pore water ion concentration and migration of fine particles with water flow,but no noticeably change in mineral composition.During seepage,the metastable structure of intact loess collapses,the fine particles disperse around the skeleton particle to fill the pores,and the total porosity decreases.The permeability coefficient gradually decreases with seepage time and then tends to a constant.The saturated intact loess shows strongly contractive behavior during undrained shear and has considerable liquefaction potential.After seepage,the intact loess is characterized by more rapid build-up of pore water pressure and more intense strain-softening during shearing and has lower shear strength(including peak strength and steady-state strength).In irrigated loess tablelands,long-term seepage could weaken the shear strength of intact loess and increases its liquefaction potential,which contributes to the initiation of loess flowslide failure and the movement with high-speeds and long run-outs. 展开更多
关键词 intact loess Long-term seepage Undrained shear behavior Static liquefaction Flowslides
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Study on radon release of intact rocks during direct shear
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作者 LI Ling-yu ZHANG Chuan-qing +3 位作者 TAO Zhi-gang CUI Guo-jian GUO Yu-hang ZHOU Hui 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第12期4021-4034,共14页
Radon is a polluting and radioactive gas released by rock fracture. Shear fracture is widely developed in surrounding rock mass of deep engineering. Nevertheless, the correlation between radon release and the shear fr... Radon is a polluting and radioactive gas released by rock fracture. Shear fracture is widely developed in surrounding rock mass of deep engineering. Nevertheless, the correlation between radon release and the shear fracture is undefined. In this study, the intact Jinping marble and Baihetan basalt were adopted as samples. Based on radionuclide content analysis, the intrinsic characteristics of radon emission were analyzed. Then a direct shear testing system was designed to synchronously measure radon release during rock fracture. The direct shear tests were carried out under different normal stresses. The relationship between shear fracture process and cumulative radon concentration was explored. The results indicated that radon release varied with the increase of shear displacement under the same normal stress. The general pattern showed a slight increase and fell in the initial loading phase, then increased rapidly to the peak release approximately corresponding to the peak of shear stress, and finally decreased to a stable level with the development of shear displacement after sample failure. The initial and peak radon concentrations increased linearly with the increase of normal stress. The same trend was found in shear failure surface area and cumulative radon concentration according to the rise angle(RA) value-average frequency(AF) distribution. 展开更多
关键词 radon release intact rock shear failure acoustic emission deep underground engineering
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Innovative use of intact seeds of Mucuna monosperma Wight for improved yield of L-DOPA
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作者 Shrirang INAMDAR Swati JOSHI +1 位作者 Jyoti JADHAV Vishwas BAPAT 《Natural Products and Bioprospecting》 CAS 2012年第1期16-20,共5页
The drug L-DOPA has been widely used against Parkinson's disease and is extracted from plants.Due to the increasing demand of this drug,new plant sources need to be discovered in addition to the existing sources.T... The drug L-DOPA has been widely used against Parkinson's disease and is extracted from plants.Due to the increasing demand of this drug,new plant sources need to be discovered in addition to the existing sources.The paper embodies results on Mucuna monosperma,which can be a promising candidate for L-DOPA.The seed powder of this plant contains 5.48%of(dry weight)the drug and when the seeds were soaked in distilled water,content was increased to 6.58%.Different elicitors when added,enhanced the drug level in seed up to 11.8%.The possible rationale behind this increase was confirmed by increase in tyrosinase activity in the seeds.Presence of L-DOPA was confirmed using various analytical techniques as HPLC,HPTLC and NMR.The work demonstrates a potential candidate plant as a source for L-DOPA when a novel method was adopted as described here. 展开更多
关键词 3-(3 4-dihydroxyphenyl)-L-alanine ELICITORS intact seeds Mucuna monosperma Parkinson’s disease TYROSINASE
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