含有延迟的Laplace逆变换的求解

在总结Laplace逆变换计算方法的基础上，举例说明了Laplace反演公式，有时并不适用于含有延迟的Laplace逆变换求象原函数．主要是因为部分含有延迟的Laplace变换所对应的象原函数是分段函数．遇此情形，只有使用其他方法求解Laplace逆变换．     

综采工作面端头液压支架分析与合理选用

随着综采技术的发展,综采工作面端头顶板事故虽逐年减少,但事故率仍居高不下,改善综采工作面端头的支护状况,实现综采工作面高产高效和提高安全程度显得尤为重要,所以端头既是项板维护的重点,又是顶板管理的难点。     

Inverse Opal Scaffolds with an Embossed Surface Pattern Prepared from Sticky Golf‐Ball‐Shaped Microparticle Assemblies

Inverse opal scaffolds presenting an embossed‐pattern surface are prepared from colloidal crystal assemblies of uniformly sized golf‐ball‐shaped microparticles. Post‐treatments, such as thermal annealing during the bridging of the microparticles for opal preparation, are avoided to prevent deterioration of surface patterns of the sacrificial template. This presents a new approach to increase the surface‐area‐to‐volume ratio (SAV) by the alteration of morphological features in sophisticated 3D structures that remain largely unexamined owing to difficulties in their preparation. Previous results observed in 2D surfaces that show effective performance improvement through an increase in contact area, especially in biomedical applications, also appear applicable to patterned inverse opal scaffolds based on comparable results obtained from cell cultures. As the field of application of opal and inverse opal structures is expanding due to their unique structural advantages, such as 3D interconnectivity and periodic structures, our strategy opens the door for the use of patterned surfaces on highly sophisticated 3D structures, improving their performance via an increase in SAV.     

反演分析法在滑坡治理中的应用

以某滑坡为例,根据现场踏勘确定了滑坡的破坏形式,在滑坡极限平衡状态下,采用传递系数法反算求得了滑坡的抗剪强度值,提出了通过在滑坡主滑段卸载的方法治理滑坡,并阐述了具体的施工方案,以有效控制滑坡的滑动变形。     

沉井逆作法施工技术

以太原市集中供热联网工程东中环主干线北沙河处的热力小室为例,根据实际情况,对不同施工方案的优缺点进行了分析,经比选,采用井室逆作工艺进行施工,并着重论述了沉井逆作法的施工技术要点,为今后同类工程施工提供了参考依据。     

复杂换乘地铁车站基坑支护技术分析

结合工程实例,研究了复杂换乘地铁车站基坑支护技术,对支护方案的选择作了分析,并对具体的施工过程进行了详细阐述,经过实践检测,证明了所选方案的可行性,总结出了一些值得借鉴的经验。     

A multiscale flaw detection algorithm based on XFEM

We present a novel multiscale algorithm for nondestructive detection of multiple flaws in structures, within an inverse problem type setting. The key idea is to apply a two‐step optimization scheme, where first rough flaw locations are quickly determined, and then, fine tuning is applied in these localized subdomains to obtain global convergence to the true flaws. The two‐step framework combines the strengths of heuristic and gradient‐based optimization methods. The first phase employs a discrete‐type optimization in which the optimizer is limited to specific flaw locations and shapes, thus converting a continuous optimization problem in the entire domain into a coarse discrete optimization problem with limited number of choices. To this end, we develop a special algorithm called discrete artificial bee colony. The second phase employs a gradient‐based optimization of the Broyden–Fletcher–Goldfarb–Shanno type on local well‐defined and bounded subdomains determined in the previous phase. A semi‐analytical approach is developed to compute the stiffness derivative associated with the evaluation of objective function gradients. The eXtended FEM (XFEM), with both circular and elliptical void enrichment functions, is used to solve the forward problem and alleviate the costly remeshing of every candidate flaw, in both optimization steps. The multiscale algorithm is tested on several benchmark examples to identify various numbers and types of flaws with arbitrary shapes and sizes (e.g., cracks, voids, and their combination), without knowing the number of flaws beforehand. We study the size effect of the pseudo grids in the first optimization step and consider the effect of modeling error and measurement noise. The results are compared with the previous work that employed a single continuous optimization scheme (XFEM–genetic algorithm and XFEM–artificial bee colony methods). We illustrate that the proposed methodology is robust, yields accurate flaw detection results, and in particular leads to significant improvements in convergence rates compared with the previous work. Copyright © 2014 John Wiley & Sons, Ltd.     

The geodesic dynamic relaxation method for problems of equilibrium with equality constraint conditions

This paper presents an extension to the existing dynamic relaxation method to include equality constraint conditions in the process. The existing dynamic relaxation method is presented as a general, gradient‐based, minimization technique. This representation allows for the introduction of the projected gradient, discrete parallel transportation and pull back operators that enable the formulation of the geodesic dynamic relaxation method, a method that accounts for equality constraint conditions. The characteristics of both the existing and geodesic dynamic relaxation methods are discussed in terms of the system's conservation of energy, damping (viscous, kinetic, and drift), and geometry generation. Particular attention is drawn to the introduction of a novel damping approach named drift damping. This technique is essentially a combination of viscous and kinetic damping. It allows for a smooth and fast convergence rate in both the existing and geodesic dynamic relaxation processes. The case study was performed on the form‐finding of an iconic, ridge‐and‐valley, pre‐stressed membrane system, which is supported by masts. The study shows the potential of the proposed method to account for specified (total) length requirements. The geodesic dynamic relaxation technique is widely applicable to the form‐finding of force‐modeled systems (including mechanically and pressurized pre‐stressed membranes) where equality constraint control is desired. Copyright © 2014 John Wiley & Sons, Ltd.     

Formulation and characterization of Brucea javanica oil microemulsion for improving safety

Objective: This study engaged in investigation of optimal formulation, characteristics analysis of Brucea javanica oil microemulsion (BJOM) in order to address safety concerns and make recommendations for improvements in BJOM safety during clinical use in vivo.

Methods: Pseudo-ternary phase diagram techniques were used to determine the appropriate ratio of surfactant, cosurfactant and oil phases. Subsequent stability testing of BJOM was performed by dilution, centrifugation and accelerated stability testing. The results were expounded through additional assessment utilizing the classical thermostat method to establish the shelf life of the material. These results were utilized to evaluate the safety of BJOM by haemolytic, irritative and allergic testing in vitro. In addition, the cytotoxicity of BJOM was examined using the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), with particular emphasis given to potential uses in cancer treatment.

Results: The most suitable method of preparation for BJOM was found to be a one to one ratio (K_m 1:1) of Solutol HS15 surfactant matched with sorbitol cosurfactant in the ratio. The microemulsion droplets of BJOM possessed a spherical shape, uniform size and average diameter of 23.8?nm. The expiration date of BJOM was found to be 568?d. The safety study demonstrated no hemolysis activity at the experimental BJOM concentrations; however, mild hemolysis was observed at higher concentrations of Brucea javanica oil emulsion (BJOE), a common commercially available product. Irritation observed upon BJOM treatment can be primarily attributed to Brucea javanica oil (BJO) with little influence of BJOM excipients. In addition, BJOM caused no observed hypersensitivity or other visible allergic reactions in guinea pigs. The anticancer activity curves of BJOM and BJOE demonstrate that both BJOM and BJOE inhibit Hela cells, with BJOM demonstrating significantly more dramatic anticancer activity.

Conclusion: An optimal formulation of BJOM superior to commercially available products and safe for medical application such as intravenous injection has been outlined along with its anticancer activity rating.     

多激励识别的自适应延迟逆系统方法

针对现有逆系统方法依赖状态空间模型的缺点提出采用系统自适应延迟逆模型识别多激励时间历程。采用自适应算法对系统进行延迟逆模型辨识,结合逆模型利用工作状态响应数据识别时域载荷。以简支梁为研究对象用无噪声干扰、有噪声干扰加速度响应识别多点稳态激励及多点非稳态激励。仿真结果表明,噪声干扰时识别精度有所降低,但较满意,验证该方法对多激励源识别的可行性。