Catastrophes of Elastic Column Structures

The elasto-static instability phenomena of structures can be typically classified by the catastrophe theory in the local form near a certain singular point of their total potential energy. Then, the imperfection sensitivity of the structures can be evaluated in terms of the bifurcation set, mapping the singular points of the equilibrium space to the control space. In ordinary structural problems, this consists of a simple loading parameter and some imperfection parameters. In this paper, several simplified column models are studied by the catastrophe theory. They include both continuous and discrete models exhibiting stable symmetric, unstable symmetric, asymmetric and their compound buckling. From a comparison of the results of the two-degree-of-freedom systems, namely the continuous systems and the finite element discrete systems, the following conclusions are drawn : (i) The discrete analysis can be shown to realize the instability phenomena, predicted by the continuous analysis. The results of the discrete analysis are shown to converge to those of the continuous analysis generally, as the number of discrete finite elements increases. (ii) The imperfection sensitivity of the structures can be evaluated qualitatively and quantitatively by means of the bifurcation set in the control space through the catastrophe theory. (iii) For a legitimate evaluation of the “cusp and dual cusp catastrophe”, the 4th order non-linear terms must be earnestly considered in expressions for both the strain energy and the external work. Then, the stable symmetric buckling model is shown to indicate a typical cusp catastrophe. (iv) The unstable symmetric buckling model can be shown to indicate a typical dual cusp catastrophe for a relatively small stiffness of the elastic foundation, the cusp catastrophe for a relatively large stiffness and the compound double cusp catastrophe at a certain critical stiffness value. (v) The asymmetric buckling model can be shown to indicate the typical fold catastrophe for a relatively small stiffness of the inclined elasic foundation, the dual cusp catastrophe for a relatively large stiffness and the compound hyperbolic umbilic catastrophe at a certain critical stiffness value

On the Initial Imperfections and Their Relations to the Strength of Webplates of Actual Steel Bridges

This study is mainly concerned with statistical investigations on the actual initial imperfections and their relations to the load carrying capacities of the webplates of steel bridges. The basic data to be used throughout the study have been collected by the Initial Deflection Measurement Committee, IDMC, of the Society of Steel Construction of Japan, abbreviated as JSSC. In order to show what types of webplate systems are covered throughout the study, various statistical information on the mechanical and geometric parameters is firstly presented, and then, various kinds of the initial imperfections existing in the actual steel bridges are subjected to statistical considerations. Through the statistical analyses, the probabilities of exceedance of various imperfections are evaluated. From these fractile values, some comments on the regulations of the initial imperfections by the current design codes are drawn

Catastrophe Analysis of Structures by Discretization and Modal Transforms

This paper is concerned with the catastrophe of static instability of multi-degree-of-freedom systems representing typical civil engineering structures like beams, columns, arches, plates and stiffened plates. The proposed method makes use of discretization methods, such as a finite element method and a simplified element method, and also some diffeomorphic transformations similar to modal analysis. The main interest of the study is the classification of the catastrophe of the structures through the evaluation of certain derivatives of potential in the light of the Thorn and Thompsons' theories. Numerical illustrations were performed on the structures, including elastically supported columns, plates, stiffened plates, lateral buckling of beams and shallow arches. Among new findings, the unstable symmetric buckling for lateral buckling, and hyperbolic umbilics for the simultaneous buckling of stiffened plates and of elastically supported columns are particularly noted

Nutraceutical Approach for Preventing Obesity-Related Colorectal and Liver Carcinogenesis

Obesity and its related metabolic abnormalities, including insulin resistance, alterations in the insulin-like growth factor-1 (IGF-1)/IGF-1 receptor (IGF-1R) axis, and the state of chronic inflammation, increase the risk of colorectal cancer (CRC) and hepatocellular carcinoma (HCC). However, these findings also indicate that the metabolic disorders caused by obesity might be effective targets to prevent the development of CRC and HCC in obese individuals. Green tea catechins (GTCs) possess anticancer and chemopreventive properties against cancer in various organs, including the colorectum and liver. GTCs have also been known to exert anti-obesity, antidiabetic, and anti-inflammatory effects, indicating that GTCs might be useful for the prevention of obesity-associated colorectal and liver carcinogenesis. Further, branched-chain amino acids (BCAA), which improve protein malnutrition and prevent progressive hepatic failure in patients with chronic liver diseases, might be also effective for the suppression of obesity-related carcinogenesis because oral supplementation with BCAA reduces the risk of HCC in obese cirrhotic patients. BCAA shows these beneficial effects because they can improve insulin resistance. Here, we review the detailed relationship between metabolic abnormalities and the development of CRC and HCC. We also review evidence, especially that based on our basic and clinical research using GTCs and BCAA, which indicates that targeting metabolic abnormalities by either pharmaceutical or nutritional intervention may be an effective strategy to prevent the development of CRC and HCC in obese individuals

Angiotensin II type 1 receptor expression in ovarian cancer and its correlation with tumour angiogenesis and patient survival

Angiotensin II, a main effector peptide in the renin–angiotensin system, acts as a growth-promoting and angiogenic factor via type 1 angiotensin II receptors (AT1R). We have recently demonstrated that angiotensin II enhanced tumour cell invasion and vascular endothelial growth factor (VEGF) secretion via AT1R in ovarian cancer cell lines in vitro. The aim of the present study was to determine whether AT1R expression in ovarian cancer is correlated with clinicopathological parameters, angiogenic factors and patient survival. Immunohistochemical staining for AT1R, VEGF, CD34 and proliferating cell nuclear antigen (PCNA) were analysed in ovarian cancer tissues (n=67). Intratumour microvessel density (MVD) was analysed by counting the CD34-positive endothelial cells. Type 1 angiotensin II receptors were expressed in 85% of the cases examined, of which 55% were strongly positive. Type 1 angiotensin II receptors expression was positively correlated with VEGF expression intensity and MVD, but not with histological subtype, grade, FIGO stage or PCNA labelling index. In patients who had positive staining for AT1R, the overall survival and progression-free survival were significantly poor (P=0.041 and 0.017, respectively) as compared to those in patients who had negative staining for AT1R, although VEGF, but not AT1R, was an independent prognostic factor on multivariate analysis. These results demonstrated that AT1R correlated with tumour angiogenesis and poor patient outcome in ovarian cancer, suggesting its clinical potential for a novel molecular target in strategies for ovarian cancer treatment

Role of host genetics in fibrosis

Fibrosis can occur in tissues in response to a variety of stimuli. Following tissue injury, cells undergo transformation or activation from a quiescent to an activated state resulting in tissue remodelling. The fibrogenic process creates a tissue environment that allows inflammatory and matrix-producing cells to invade and proliferate. While this process is important for normal wound healing, chronicity can lead to impaired tissue structure and function

Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks

无线传感器网络，作为全球未来十大技术之一，集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术，可实时感知、采集、处理、传输网络分布区域内的各种信息数据，在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议，并针对大规模的无线传感器网络设计了一种树状路由协议，它根据节点地址信息来形成路由，从而简化了复杂繁冗的路由表查找和维护，节省了不必要的开销，提高了路由效率，实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR（AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位：工学硕士院系专业：信息科学与技术学院通信工程系_通信与信息系统学号：2332007115216