土石坝的动态反应：离心机模型试验与数值模拟

为评估LIQCA程序是否能合理分析台湾仁义潭土石坝在地震时的反应,进行3个土石坝离心机模型试验,并对相同的土石坝与振动历时进行LIQCA动态数值分析。通过动态数值分析与离心机模型试验结果,探讨土石坝受震时超孔隙水压力的激增以及土体加速度在坝体不同填土区的变化,并评估LIQCA程序耦合在仿真土石坝受震时的可靠性。     

Local side-effects during 4-year treatment with inhaled corticosteroids--a comparison between pressurized metered-dose inhalers and Turbuhaler

Local side-effects, such as hoarseness and oropharyngeal candidiasis, are often seen during treatment of patients with inhaled corticosteroids (ICS). We investigated whether changing from pressurized metered-dose inhalers (pMDI) to Turbuhaler influenced the type and frequency of local side-effects. Local side-effects were recorded for a 2-year period in which 154 patients used ICS pMDI with a spacer device. They were followed for an equally long period of time (26.2 +/- 5.7 months) while using Turbuhaler, as were 90 patients who received Turbuhaler as their first ICS preparation. After inhalation, all patients rinsed out their mouths with water. In experienced pMDI-users, the frequency of local side-effects decreased from 21% to 6%. The reduction was due to a lower incidence of hoarseness. Candidiasis or hoarseness was not seen in patients given Turbuhaler as their first ICS device. Our fear of an increased incidence of local side-effects when giving ICS in Turbuhaler was unwarranted.     

A survey of hospital diet. Connection between the nutritive value found by analysis and by calculation

The primary aim of this study is to determine the nutritional quality of the food prepared in a selected Danish hospital. Samples consisted of four double portions of the hospital's standard daily ration from two randomly chosen weeks. The amounts of fatty acid, protein, ash, total dry material, and vitamin C were measured. The amount of carbohydrate, energy, and percentage of available energy were calculated. The total energy level was measured to eight MJ per day. The measured percentage of available energy given as protein (17%) and the vitamin C levels (14 mg/MJ) have fulfilled the recommendations. The percentage of energy given as carbohydrates (38%) is below and the percentage of energy given as fat (45%) is above the recommended levels (50% and 32%). There is a direct correlation between the average calculated and the average measured values when all of the meals are analysed as an entity, but the correlation is weak for individual meals.     

Morphology of step-wise S–N curves depending on work-hardened layer and humidity in a high-strength steel

The present paper describes the effects of work‐hardened layer and humidity on the fatigue response of high strength steel, JIS SNCM439 (AISI4340). Tests were conducted in laboratory air and in dry air using cantilever‐type rotating bending fatigue testing machines. The dew point of dry air was ?60 °C. Specimens with two different surface conditions were prepared, i.e., buff‐finished and electro‐polished specimens. In the buff‐finished specimens, a stepwise S–N curve was seen in both environments, but the transition stress below which subsurface crack initiation occurred shifted to a higher stress level in dry air than in laboratory air. In the electro‐polished specimens, stepwise S–N curve was not observed in laboratory air, but seen in dry air. At stress levels where cracks initiated at the surface, the fatigue lives of the electro‐polished specimens were shorter than those of the buff‐finished specimens. At stress levels where subsurface cracks initiated, the fatigue lives of both specimens were the same, irrespective of surface finishing condition and humidity.     

基于光学相干层析气冲印压技术研究角膜生物力学特性

结合频域光学相干断层层析术(SDOCT)以及空气脉冲印压技术(OCT气冲印压系统)研究了角膜的生物力学特性。采用热成型硅胶模拟角膜形态设计制作了8种不同硬度的角膜仿体,通过联接吊瓶和压力传感器控制并设定角膜仿体的前房压力。运用快速气脉冲作用于角膜,同时用OCT记录角膜整个动态形变过程,测得了角膜仿体形变参数——最大压陷深度(DA),并分析得到了反映角膜生物力学特性的硬度系数。结果显示:角膜仿体中央的实际厚度为(504.12±17.04)μm,不同硬度硅胶的角膜仿体的杨氏模量为90~1 400kPa,同一角膜仿体的杨氏模量值与模拟前房眼内压成正相关。同一眼内压下3次重复性实验表明OCT系统测量参数DA具有很高的重复性(ICC=0.992 6);不同观察者A和B的一致性实验表明,DA具有很好的一致性(差值均值为1.1μm)。不同眼压下所得仿体角膜的硬度系数与传统的拉伸实验测得的该仿体的杨氏模量具有明显的相关性(r=0.99,P0.001)。得到的测试结果表明,OCT气冲印压系统可以用来检测角膜生物力学特性,系统测量结果精确可靠。     

Overlapping nuclei segmentation based on Bayesian networks and stepwise merging strategy

This paper presents a new approach to the segmentation of fluorescence in situ hybridization images. First, to segment the cell nuclei from the background, a threshold is estimated using a Gaussian mixture model and maximizing the likelihood function of the grey values for the cell images. After the nuclei segmentation, the overlapping and isolated nuclei are classified to facilitate a more accurate nuclei analysis. To do this, the morphological features of the nuclei, such their compactness, smoothness and moments, are extracted from training data to generate three probability distribution functions that are then applied to a Bayesian network as evidence. Following the nuclei classification, the overlapping nuclei are segmented into isolated nuclei using an intensity gradient transform and watershed algorithm. A new stepwise merging strategy is also proposed to merge fragments into a major nucleus. Experimental results using fluorescence in situ hybridization images confirm that the proposed system produced better segmentation results when compared to previous methods, because of the nuclei classification before separating the overlapping nuclei.     

斜拉索张力测试和参数评估的理论和应用

基于较完善的有限元模型,通过最小化频率测量值与计算值间的误差,建立了利用多阶测试频率识别斜拉索张力、长度、抗弯刚度、线密度以及支撑条件等多个参数的基本理论,极大地提高了斜拉索张力测试的准确度和可靠度。作为实例,对洞庭湖大桥的斜拉索进行了张力测试和参数评估。