Plastic slip stability analysis of gangue granular media

This paper studies the landslide mechanism by the analysis of accumulation form, topography and geomorphology, self structure and natural river system of Weijiagou coal gangue hill. The limit state function is established based on plasticity mechanics limit analysis upper bound theorem and Bishop slices method, combining reliability theory. The safety coefficient and reliability index of Weijiagou coal gangue slope is calculated. The plasticity limit analysis upper bound theorem can consider the interior stress strain relation of soil, so the formula derivation process is stricter. It is the consideration of the variability of gangue parameters that making the evaluation result more reasonable.     

土体抗剪强度指标变异水平对边坡稳定安全系数取值的影响

针对传统的边坡稳定极限平衡方法不能考虑土体抗剪强度指标变异性影响的问题,基于极限状态的概率分析原理,采用Monte-Carlo法对均质路堤边坡的稳定性开展了可靠度计算,讨论了稳定安全系数一定的条件下边坡失效概率随土体抗剪强度指标变异水平的变化规律,分析了安全系数与边坡可靠指标的对应关系及其随土体抗剪强度指标变异水平的变化特征。研究表明：边坡可靠度受土体抗剪强度指标变异性影响显著,呈现出随土体抗剪强度指标变异水平提高而急剧减小的趋势;为保证边坡具有相同的可靠性,安全系数的取值应与土体抗剪强度指标的变异性相适应,据此提出了基于可靠指标和土体抗剪强度指标变异水平的安全系数取值原则及其对应的三参数函数关系式。     

Finite Element Reliability Analysis of the Stability of a Slope

The whole reliability index of a slope is derived through using the strength reduction method in the finite element analysis, which can make use of the former finite element program and can be used to both linear and nonlinear finite element analysis. The affection of the evaluation of derivative and the selection of reliability analysis methods is discussed, which shows that it is very important to select the type of limit state function of the slope stability. A new iterafive formula, which can consider the correlation of fundamental parameters, is proposed for FORM, and the convergence is very well.     

Research on Index of Reliability for Bearing Capacity of Rock - Socketed Single Pile in Chongqing

Based on the data from in-situ 102 rock-socketed test piles in Chongqing in recent 10 years and utilizing the limit state equation of the dimensionless random variables,the reliability analysis of the bearing capacity of rock-socketed single pile is made and the scope of the target reliability of rock-socketed piles in Chongqing is calculated with both JC method and Monte-Carlo method respectively.Furthermore,the target index of reliability is suggested.Finally,the concept of reliability coefficient(to replace the load partial factor and the resistance partial factor) is given and the bearing capacity of the single pile is determined by utilizing optimization method.Besides,the practical limit state design equation using reliability coefficient is put forward for its advantage of incarnating the simple and practical principle and being easy mastered and understood by the designers.     

ANSYS/PDS风电齿轮箱收缩盘联接可靠性分析

笔者建立了某风电齿轮箱主轴收缩盘联接的轴对称参数化有限元模型,并结合主轴扭矩作用应用ANSYS非线性接触对该模型进行了强度分析。由于材料属性、制造过程、边界条件以及载荷等设计参数的不确定性会影响计算的精确性,应用ANSYS/PDS模块,根据失效模式确定整体功能函数并由此建立结构极限状态方程,采用蒙特卡罗超拉丁采样方法对收缩盘联接进行可靠性分析,得到整体联接的可靠度和失效率,并给出累积概率分布。研究结果表明:收缩盘传扭联接性能和结构件强度均满足设计要求,其联接的可靠度达到94.8%,达到了工程设计要求,对风电齿轮箱收缩盘联接的可靠性设计具有一定的指导意义。     

非线性Mohr-Coulomb破坏准则下边坡可靠度上限

传统边坡可靠度分析往往在岩土参数服从线性Mohr-Coulomb（简称线性M-C）破坏准则的假设条件下进行,并且常常采用极限平衡法或有限元法计算安全系数。然而,岩土介质破坏准则具有一定的非线性。为能更加实际地描述岩土破坏机理和得到严格精确的解,基于非线性Mohr-Coulomb（简称非线性M-C）破坏准则,结合极限分析上限法和蒙特卡洛法,进行边坡可靠度上限分析。当非线性参数m=1时,与等效的线性M-C破坏准则进行对比计算,验证了方法的可行性。同时,将初始粘聚力、内摩擦角arctan（c₀/σ_t）和非线性参数作为随机变量且服从截断正态分布,进行了参数变异性和敏感性影响分析。研究表明：非线性M-C破坏准则下,边坡可靠度随初始粘聚力、内摩擦角arctan（c₀/σ_t）和非线性参数变异性的增大而减小;边坡可靠度随初始粘聚力和内摩擦角arctan（c₀/σ_t）的增大而增大,随非线性参数的增大而减小。     

白银市低丘缓坡土地建设开发适宜性评价

为了拓展城市用地发展空间,解决城市用地紧张问题,逐步提高低丘缓坡土地为各类建设的供地能力,通过采用级差正规化法和熵值法,研究白银市三县两区低丘缓坡土地开发成建设用地的适宜性程度。结果表明,景泰县和靖远县的低丘缓坡土地建设开发适宜性为高度适宜,平川区和白银区为中度适宜,会宁县为低度适宜。通过研究最终得出景泰县、靖远县、白银区和平川区的低丘缓坡土地开发成建设用地的整体条件较好,适宜性程度较高,在当前条件下适宜开发成建设用地;会宁县低丘缓坡土地现有条件较差,不适宜开发成建设用地,但通过一定的生物措施和工程措施后,可改善区域条件,在未来条件下可进行开发。     

The utility of hill plots in oat research

From 1955 through 1963, approximately 300,000 hill plots have been used in various experiments in the Iowa small grain research program. When grain yield, plant height, and heading date were measured on the same varieties, the genetic correlations between rod rows and hills were 0.98, 0.96 and 0.96, respectively.The coefficients of variation for plant height, weight per volume, spikelets per panicle, panicles per plant, weight per 100 seeds were similar for rod rows and hills. However, the coefficients of variability for grain yield ranged from 2 to 5 times larger for hills than for rod rows. Competition between varieties in adjacent hills had little effect on the performance of varieties.The best method for planting hill plots is the conventional method opening a hole in the soil about 2 inches deep with a hoe, pouring the seed in the hole, and covering it with soil. Rates of planting influenced the expression of grain yield, panicles per plant, and spikelets per panicle, but not weight per 100 seeds and plant height. Approximately 30 seeds per hill appeared the most desirable planting rate.Journal Paper No. J-5064 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa. Project No. 1176. Received for publication Febr. 23, 1965. In cooperation with the Crops Research Division, Agricultural Research Service, U. S. Department of Agriculture.Professor of farm crops.     

The Recent Progress of the Slope Stability Analysis Methods

The slope stability is an important research content in rock mechanics. In recent years, the great achievement has been gained for the slope stability analysis methods. The deterministic analysis methods, including limit equilibrium theory, numerical analysis method, graphic method and compound method, have been developed. The stochastic analysis method and the fuzzy analysis method come forward. The recent progress of the slope stability analysis methods is analyzed in this paper. The trend of progress of the slope stability is studied.     

Analysis on the stability of traffic flow with the information of two preceding cars

The stability analysis is one of the important problems in the traffic flow theory, where the congestion phenomena can be regarded as the instability and the phase transition of a dynamical system. An extended optimal velocity model is deduced by considering the effect of the information of two leader cars. The stability condition of the extended model is obtained by using the linear stability theory. The modified Korteweg-de Vries (mKdV) equation is derived to describe the traffic behavior near the critical point by applying the nonlinear analysis. The numerical simulation results demonstrate the analytical results and show that the traffic congests are suppressed more efficiently by considering two vehicles ahead. Therefore, the next-nearest-neighbor car has strong effects on traffic dynamics and plays an important role on stabilizing the traffic flow.     

Constitutive Description of Precreep-Plasticity with Experimental Verification

In this paper we put forword a constitutive model based on thermodynamics,Byintroducing generalized time scale, unified constitutive equation including descoription of creep,plasticity and the creep-plasticity interaction effects, is presented,It is shown that the present unifiedconstitutive equation includes plasticity as one special case(dt=0)and creep as the other one(ds=0).By means of analysis of material subetructure for creep, plasticity and creep-plasticityinteraction,a multiplicative harderung function analysis developed here has been compared with Ohashi'sexperimental results,It seem that the present theory could satisfactorily describe Ohashi'sexperimental results.     

VARIABLE DAMP STRUCTURAL RELIABILITY DUE TO MULTIPLE RANDOM EXCITATIONS AND SENSETIVITY ANALYSIS

The reliability of random vibration is discussed,and then by using the first order perturbation method and with the aid of relation of the systemic response function to the first order sensetivity of variable damp parameter, the rate of change of structural reliability indication is derived, therefore the constraint equation to guarantee reliability for the structural optimization design is proved and the satisfactory result is obtained,test and the practicability of this method is tested.     

NLPNN Model in Power Systems Reliability Evaluation

The purpose of a power system is to deliver the power the customers require in real time, on demand, within acceptable voltage and frequency limit, and in a reliable and economic manner. Using NLPNN (New Linear Programming Neural Network) model, the behavior analysis of power system under fault conditions is carried through. The stability and convergence theorems are set up to obtain the resolution for the problem of the load curtailment strategy. A new way is open up to evaluate the reliability of power systems and the great progress in calculation analysis model is achieved. The new calculation technique and theory foundation of reliability evaluation are supplied.     

水稻合理密植及其优质高产机理研究进展

合理密植是水稻高产优质栽培的重要措施之一,包括合理的每蔸基本苗数、单位面积蔸数和行株距配置三部分。此文从每蔸基本苗数、单位面积蔸数和行株距配置3个方面综述了栽插密度对水稻群体产量和品质的影响,以期为水稻高产优质提供理论指导。     

低氮密植栽培对超级稻产量和氮素利用率的影响

为了研究低氮密植栽培对水稻分蘖发生及成穗率、干物质积累及其转化、氮素利用率和产量的影响,2012—2013年以超级稻Y两优1号为材料,在湖南长沙和海南澄迈进行了施氮量(75、150、225 kg N hm–2)与栽插密度(68、40、27、19穴m–2),每穴苗数(单、双、三本穴–1)与栽插密度(40、27、19、14穴m–2)的大田栽培试验。结果表明,在基本苗数相同或相近的条件下,减苗增密在齐穗期和成熟期的干物质量及产量分别比增苗减密高10.5%、5.2%和2.9%,有效穗数对产量的贡献最大,达到显著水平;在低氮密植条件下,有效分蘖期缩短6 d左右,分蘖成穗率、表观转化率、氮肥偏生产力和氮素籽粒生产效率分别提高10.9%、21.0%、150.6%和19.6%。在施氮量为75 kg N hm–2的密植(40~68穴m–2)条件下,齐穗期和成熟期的干物质量及长沙点产量分别比中、高氮(150~225 kg N hm–2)常规密度(19~27穴m–2)低3.2%、7.5%和1.2%,但差异不显著,而澄迈点产量在2012年和2013年分别比之低5.2%和高9.1%,且差异均达显著水平。在施氮量为150 kg N hm–2的密植条件下,成熟期干物质量比高氮常规密度低1.7%,但齐穗期干物质量和产量比高氮常规密度高10.3%和3.3%。因此,超级稻采用低氮密植栽培,在100~150 kg N hm–2和40穴m–2条件下提早了够苗期,增加了有效穗数,提高了分蘖成穗率和结实率,加之齐穗期适宜的干物质积累和较高的表观转化率,有利于高产的形成和氮肥利用率的提高。     

水稻机插缺丛条件下自然补偿能力研究

为了提高机插水稻的产量和经济效益,通过田间模拟缺丛试验,研究缺丛对产量造成的影响及其自然补偿能力。结果表明,在缺丛率为0%(CK)、5%、10%、15%、20%五个处理中,水稻产量随着缺丛率增加而下降,减产幅度为2.5%~6.3%,缺丛率达10%以上,减产达显著水平。缺丛四周植株分蘖增强,而成穗率下降不太明显,有效穗数增加,单丛产量增加,从而对缺丛起到补偿作用,补偿作用随着缺丛率提高而增强。但仍不能完全弥补因缺丛所带来的穗数损失,导致减产。同时每穗总粒和实粒数、千粒重也随着缺丛率提高而相应有所降低。因此,机插水稻缺丛在所难免,缺丛率要控制在5%以下,当缺丛率达到10%以上时,应适当进行人工补缺,达到增产增效的目的。     

优质抗病杂交粳稻滇杂31不同海拔适宜栽插密度初探

通过对优质抗病滇型杂交粳稻滇杂31不同栽插密度在云南温暖粳稻区的牟定县和温凉粳稻区的大理市进行试验,试验结果分析表明：滇杂31在温暖粳稻区的栽插密度以30.0万丛/hm2,2苗/丛产量最高,不同栽插密度之间产量差异达极显著水平;在温凉粳稻区的栽插密度以45.0万丛/ hm2,2苗/丛产量最高,不同栽插密度之间产量差异达显著水平。     

优质抗病杂交粳稻滇杂31不同海拔适宜栽插密度初报

通过对优质抗病滇型杂交粳稻滇杂31不同栽插密度在云南温暖粳稻区的牟定县和温凉粳稻区的大理市进行试验,试验结果分析表明:滇杂31在温暖粳稻区的栽插密度以30.0万丛/hm2,2苗/丛产量最高,不同栽插密度之间产量差异达极显著水平;在温凉粳稻区的栽插密度以45.0万丛/hm2,2苗/丛产量最高,不同栽插密度之间产量差异达显著水平。     

Grain yield and its components in spring barley under row and hill plot conditions

Twenty homozygous barley lines were grown in row and hill plots at two locations in Ontario in 1973. The hill plots were of two spacings –30×30 cm and 45×45 cm between hills. Within each spacing, three seeding rates were used i.e. 15, 25 and 35 seeds per hill. Grain yield and three of its components, namely; number of seeds per spike (NSS), number of spikes per plot (NSP) and seed weight (SW) were studied. It was concluded that both NSS and SW could be evaluated in hill plots. NSS was found to be an important component of grain yield and its relationship with grain yield was unaffected by plot types and locations. SW also remained unaffected by plot types and seeding rates but as a component of grain yield it was the least important of the three components measured. The correlation between SW and grain yield could be changed by locations. NSP was as important as NSS as a component of grain yield, and was highly correlated with grain yield. Unlike NSS, NSP could not be efficiently evaluated in hill plots since its correlation between row and hill plots was generally lower.