Limit equilibrium analysis for stability of soil nailed slope and optimum design of soil nailing parameters

Reinforcement of slopes using soil nailing can effectively improve slope stability, and it has been widely used in upgrading cut slopes. Based on the assumptions of stresses on the slip surface, a new method for analyzing the stability of a slope reinforced with soil nails was established in the limit equilibrium theory framework, by considering that slope sliding occurs owing to shear failure of the slip surface, which subjects to Mohr–Coulomb(M–C) strength criterion. Meanwhile, in order to easily analyze the stability of a soil nailed slope in actual engineering and facilitate optimum design of parameters for soil nailing, factor of safety(FOS) contour curve charts were drawn on the basis of the established linear proportional relationship between the spacing of soil nails and slope height, and the length of soil nails and slope height. Then, by analyzing and verifying the results obtained from classic examples, some conclusions can be got as follows: 1) The results obtained from the current method are close to those obtained from the traditional limit equilibrium methods, and the current method can provide a strict solution for the slope FOS as it satisfies all the static equilibrium conditions of a sliding body, thus confirming the feasibility of the current method; 2) The slope FOS contour curve charts can be used not only to reliably analyze the stability of a soil nailed slope, but also to design optimally the parameters of soil nailing for the slope with a certain safety requirement.

A Study on the Stability Analysis and Optimum Design for Journal Bearings

Based on the establishment of a differential equation of motion and the solution of the oil film whirling locus of the Journal center, a method of judging the stability of bearing is presented. Meanwhile a method of bearing parameter optimization for the optimal stability is recommended. Finally, a short journal bearing is given as an example to illustrate the reasonableness and feasibility of the method.

Optimum line reclosing time for the enhancement of interconnected power system stability

Automatic line reclosing schemes used in an extra-high-voltage power system is an economical and effective means to maintain transient stability. A novel method is proposed in the paper to adaptively optimize the automatic line reclosing time after a transient fault for enhancement of interconnected power system transient stability. Both the study on the transient energy over network and the structure-preserving multi-machines power system model illustrate that the excessive convergence of potential energy on the lines with a certain cutset deteriorate power system stability, and therefore, an optimum line reclosing strategy can be established by minimizing the change in transient potential energy distribution across a cutset lines in the vicinity of the faulty line as an optimization target, and the optimal reclosure time is set to the time of minimum line phase angle difference. Without any pre-determined knowledge, the method is adaptive to various power system operation modes and fault conditions, and easy to implement because only a limited number of data measured at one location on a tie-line linking sub-networks are required. Simulations have been performed with the OMIB(One Machine and Infinite Bus System) and a real inter-connected power system to verify the applicability of the method proposed.

A Simple and Effective Test Method of the Emulsion Stability

An innovational test method was developed on the basis of redefinition of the emulsion stability. The stability was characterized by relative volume percentage of disperse phase demulsified thoroughly from the top part and the bottom part of an emulsion sample, each weighting the same amount, after being settled for a given time at constant temperature. Three series of emulsions were prepared and tested successfully, which were emulsions of paraffin oil and water stabilized with polyoxyethylene lauryl ether series (AEO3 and AEO9) at various HLBs, and emulsions of rapeseed oil and water stablized with sorbitan monoleate (Span80) and each of polyoxyethylene (20) sorbitan carboxylic esters (Tween20, Tween40, Tween60, Tween80 and Tween85) at different HLBs. It provedthat this method is especially workable while the boundaries are opaque in a wide range of HLBs and is capable of offering an accurate optimum HLB.

APPROACH FOR LAYOUT OPTIMIZATION OF TRUSS STRUCTURES WITH DISCRETE VARIABLES UNDER DYNAMIC STRESS, DISPLACEMENT AND STABILITY CONSTRAINTS

A mathematical model was developed for layout optimization of truss structures with discrete variables subjected to dynamic stress, dynamic displacement and dynamic stability constraints. By using the quasi-static method, the mathematical model of structure optimization under dynamic stress, dynamic displacement and dynamic stability constraints were transformed into one subjected to static stress, displacement and stability constraints. The optimization procedures include two levels, i.e., the topology optimization and the shape optimization. In each level, the comprehensive algorithm was used and the relative difference quotients of two kinds of variables were used to search the optimum solution. A comparison between the optimum results of model with stability constraints and the optimum results of model without stability constraint was given. And that shows the stability constraints have a great effect on the optimum solutions.

Optimization of Slope Angle and Its Seismic Stability: A Case Study for the Proposed Open Pit Coalmine in Phulbari,NW Bangladesh

The present study reflects upon the results of substantial program of two-dimensional Finite Element Method （FEM） numerical analyses of the open pit that links to slope angle optimization associated with the safety factor of the pit slope of a coal mine in Bangladesh. In the present analyses, two types of models have been presented. The first model estimates safety factor without seismic effect on the overall pit slope of the model; the second model incorporates safety factor with seismic stability of the model. The calculated optimum slope angle of the first model is 31% with a rational safety factor of 1.51, prior to the seismic effect. However, the value is reduced to 0.93, 0.82, and 0.72, after we applies the seismic effect in the second model with M6, M6.5, and M7, respectively. Finally, our modeling results emphasize that for the case of the proposed Phulbari coalmine, there is extremely high prospect for causing massive slope failure along the optimum pit slope angle with 31% if the mine area felt seismic shaking, like the Sikkim （in northern India） earthquake with M6.9 on September 18, 2011.

Stability analysis of underground engineering based on multidisciplinary design optimization

Aiming at characteristics of underground engineering,analyzed the feasibility of Multidisciplinary Design Optimization (MDO) used in underground engineering,and put forward a modularization-based MDO method and the idea of MDO to resolve problems in stability analysis,proving the validity and feasibility of using MDO in underground engi- neering.Characteristics of uncertainty,complexity and nonlinear become bottle-neck to carry on underground engineering stability analysis by MDO.Therefore,the application of MDO in underground engineering stability analysis is still at a stage of exploration,which need some deep research.

A micro-kinetic model of enhanced foam stability under artificial seismic wave

To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability,a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wave is established based on a vertical liquid film drainage model and elastic wave theory.The model is solved by non-dimensional transformation of the high order partial differential equations and a compound solution of implicit and explicit differences and is verified to be accurate.The foam film thickness,surfactant concentration distribution and drainage velocity under the action of low frequency artificial seismic wave are quantitatively analyzed.The research shows that low-frequency vibration can reduce the difference between the maximum and minimum concentrations of surfactant in the foam liquid film at the later stage of drainage,enhance the effect of Marangoni effect,and improve the stability of the foam liquid film.When the vibration frequency is close to the natural frequency of the foam liquid film,the vibration effect is the best,and the best vibration frequency is about 50 Hz.The higher the vibration acceleration,the faster the recovery rate of surfactant concentration in the foam liquid film is.The higher the vibration acceleration,the stronger the ability of Marangoni effect to delay the drainage of foam liquid film and the better the foam stability is.It is not the higher the vibration acceleration,the better.The best vibration acceleration is about 0.5 times of gravity acceleration.Reasonable vibration parameters would greatly enhance the effect of Marangoni effect.The smaller the initial concentration of surfactant,the better the vibration works in enhancing Marangoni effect.

Optimum Design of Highway Excavation Slope Angle: Evidence from Dawu Section of Jingzhu Highway

The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing Zhuhai) Highway is taken as an example to illustrate the study method for excavation slope angle design. The analysis of the engineering condition from different angles with different factors shows that the stability of the slope is calculated by using residual pushing force and the Sarma method. Then the sensitive analysis of the slope stability is conducted by using residual pushing force method. Finally, the optimum angle of design is presented on the precondition of ensuring the whole stability of slope and the economic reasonability. The study results show that the most sensitive factors are the shear strength parameter and the seismic force, and that the optimum excavation slope angle is 60°.

基于疫苗接种的SEIHRVI传染病模型分析与最优控制

为研究疫苗接种对控制传染病的影响,建立了具有标准发生率的传染病模型。通过推导得出模型的基本再生数,给出地方病平衡点的存在条件。借助构造Lyapunov函数证明了平衡点的全局稳定性。应用Pontryagin最大值原理分析了最优控制问题,得出最优控制策略。结果表明:提高疫苗接种率和效力能有效控制疾病传播;注意自我保护,及时接种以及重视治疗一定程度上可减小疾病爆发的规模。

双剪切复乳化喷雾干燥精氨酸微胶囊制备与性能评价

精氨酸是医药、特医食品和饲料行业广泛应用的组成分或营养添加剂。该文采用二次剪切复乳化形成精氨酸微胶囊乳液,通过喷雾干燥制备固体微胶囊。通过光学显微镜、电镜、质谱成像、电子鼻、电子舌、热重分析、体外模拟消化等系列表征和检测方法,系统分析了精氨酸微胶囊的形态、性状和消化特性,并通过稳定性试验测试了其贮藏稳定性。研究结果表明双剪切乳化可形成稳定的W/O/W型精氨酸微胶囊乳液,喷雾干燥制备的微胶囊为圆球形,平均粒径41.36μm,精氨酸负载量12.16 wt.%,主要分布于胶囊内部,包埋率为95.51%;外层水溶性壁材对精氨酸的氨味和苦涩味具有良好的掩味效果,且在模拟胃液30 min消化中较易崩解,使精氨酸缓释率达到93.14%;精氨酸微胶囊具有良好的稳定性,在室温条件下贮藏90 d精氨酸保留率达到93.82%。该研究可为精氨酸微胶囊在实际的商业应用提供理论依据。

不同市售即食海参营养品质差异分析

以市售六种即食海参为研究对象,测定其水分、粗蛋白、灰分、总糖、胶原蛋白和皂苷含量以及脂肪酸和氨基酸组成,分析其味觉特征、微观结构、热稳定性和全质构(Texture Profile Analysis,TPA)特性,并对其进行感官评价。结果表明:六种即食海参营养品质存在显著差异,水分含量为75.42%~94.68%,粗蛋白含量为55.77%~69.91%,灰分含量为4.80%~11.94%,总糖含量为10.52%~15.78%,胶原蛋白含量为22.00%~30.18%,皂苷含量为0.31%~1.21%。不饱和脂肪酸含量为12.28~22.65 mg/g,多不饱和脂肪酸含量为7.94~14.05 mg/g。氨基酸总含量为54.83~65.38 g/100 g,甘氨酸、谷氨酸和天冬氨酸含量丰富。电子舌分析滋味特征,S2、S3、S4和S5相近。六种即食海参微观结构差异较大,S1热稳定性最好,弹性、内聚性和回复性组间差异显著。感官评分S1最高为82.4,S3最低为74.3,整体上感官都可被接受。偏最小二乘法和Pearson相关性分析表明,滋气味与酸味、涩味、苦味回味、涩味回味、丰富性、咸味呈现极显著正相关(P<0.01),口感与弹性、内聚性、酸味、涩味、苦味回味、涩味回味、丰富性、咸味呈现极显著正相关(P<0.01)。上述结果可为即食海参产品开发、品质分级和相关标准制定提供一定的理论依据。

盐酸二甲双胍口服溶液制剂的研究

目的改善盐酸二甲双胍口服溶液的口感,优化制剂处方组成。方法通过处方开发风险评估,确定参比制剂中矫味剂用量范围,全因子试验设计制备自研制剂,采用电子舌和人体口尝对其进行味觉评价,结合稳定性考察结果筛选最优处方。结果电子舌测定结果显示,当矫味剂组合木糖醇占比40%、糖精钙占比0.35%、樱桃香精占比0.03%时,口感最佳,且与人体口尝评价结果相近,处方长期试验考察稳定性良好。结论采用电子舌和人体口尝法辅助矫味剂进行处方设计,可优化盐酸二甲双胍口服溶液处方组成。

用于电致变色技术的氧化钨薄膜最佳厚度的探索

WO_(3)薄膜在小直流电压作用下,通过阳离子的嵌入/脱出可以在深蓝色和透明态之间进行可逆变色.注入离子的迁移路程(即薄膜厚度)对WO_(3)电致变色性能和循环稳定性有极大影响.因此,本文采用直流反应磁控溅射制备WO_(3)薄膜,通过控制溅射时间制备得到200 nm、500 nm、800 nm、1100 nm、1400 nm 5种厚度的薄膜样品,分别测试其初始态和1000圈CV循环后的电荷储量、调制率、响应时间及记忆时间,探究用于电致变色技术的WO_(3)薄膜的最佳厚度.结果表明,800 nm厚度的WO_(3)薄膜表现出的电致变色性能和循环稳定性明显优于其他厚度,在1000圈循环后电荷储量下降了25.1%,在波长550 nm处调制率衰减了1.59%,24 h静置后透过率增加了11.73%.该研究可为WO_(3)薄膜的产业化应用提供更为精确的理论指导.

发酵菠萝酒的风味及其稳定性研究

以海南菠萝为原料,分别采用酿酒酵母和法国经典酵母在不同加糖量的条件下发酵制备菠萝酒,研究了发酵菠萝酒的感官指标,通过GC-MS方法研究了它们的香气成分;同时,研究其在室温、低温(4℃)和光照条件下的稳定性。结果表明对于当加糖量为0.10 g/g菠萝肉时,发酵所得的菠萝酒的风味最佳,酒度最高,低温保藏最佳。

果汁酸性奶冻的研制

主要介绍了一种果汁酸性奶冻的生产配方,结果发现:当CMC、卡拉胶、黄原胶与魔芋胶以3∶2∶1·2∶1·8比例复配,添加量为8‰时,可以有效改善果汁酸性奶冻的稳定性及口感。当蔗糖用量为6%,AK糖用量为0·02%时,采用柠檬酸∶乳酸∶酒石酸=1∶1∶1将产品pH调整到4·1时,产品口感爽滑,酸甜适中,有良好的咀嚼性。

岩土边坡稳定性预报的人工神经网络方法

阐述了经典边坡稳定分析方法的局限性,综合考虑了影响边坡稳定性的因素,建立基于人工神经网络的边坡稳定性预报方法。采用遗传算法优化神经网络的结构,以提高其非线性映射能力和泛化能力,从而,提高预报准确度。基于已有的工程实例训练所建立的神经网络,并对新的边坡稳定性问题进行了预报,预报结果表明,所建立的边坡稳定性预报方法具有较高的预报准确度。

脂质纳米粒提高尿酸氧化酶体外稳定性的初步研究

目的:使用Tricine-Na OH缓冲液制备含UOX的脂质纳米粒(urate oxidase lipid nanoparticles prepared by Tricine-Na OH buffer,UTLNs),并对游离尿酸氧化酶(urate oxidase,UDX)在体外的活性和稳定性进行初步研究。方法:采用逆向蒸发法制备UTLNs。分别从最适温度、最适p H、热稳定性、贮存稳定性、酸碱稳定性和抗胰蛋白酶水解能力初步考察游离UOX和UTLNs的差异。结果:游离UOX和UTLNs最适温度均为40℃;游离UOX最适p H为8.5,UTLNs最适p H为8.0;稳定性结果显示,UTLNs的体外稳定性明显优于游离UOX。结论:UTLNs不仅提高了UOX在体外的活性,并且明显地增强了UOX在体外的稳定性。

藕节形大深度潜水器耐压壳体优化设计

藕节形切弧连接耐压壳体是大深度潜水器耐压壳体的一种新型结构形式。该文考虑初始缺陷和材料、几何非线性的影响,参考潜艇规范,采用外点罚函数(OPF)法的结构优化程序,研究了三藕节切弧连接耐压壳体的优化设计。在研究中,设计变量为耐压壳体的厚度半径比、球壳间距半径比、连接角,考虑强度、稳定性以及几何约束,使浮力因子最小。同时研究了设计变量在结构优化设计中的敏感性,以及设计变量对耐压壳体的浮力因子、强度和稳定性的影响。文中的研究结果可以为藕节形大深度潜水器耐压壳体的结构设计提供参考。

大米布丁的研制

采用两组正交试验 (稳定性试验和最佳口味试验 )研究了大米布丁的生产工艺和最佳配方。试验结果表明 :以 1 %卡拉胶添加于大米布丁中 ,其稳定性最佳 ,以大米 1 0 0 g、奶粉 40 g、白糖 80 g、奶油 5g、水 70 0 g和食盐少许 ,煮沸时间 1 0 min制成的产品口味最佳。