某冶金企业噪声作业人员听力损伤的特点

目的为进一步了解太钢噪声作业人员听力损伤的特点,为控制和消除职业性噪声聋的发生提供依据。方法对15个生产厂256个噪声作业点进行现场监测。并对1 628名噪声作业人员进行健康体检,分析其噪声特性和双耳纯音听力损伤的特点。结果1 628名噪声作业人员按其接触噪声性质不同分为6个工种,听力损伤以轧钢系统岗位最严重,其次为流动性岗位,辅助性岗位最低。同时非稳态噪声听力损伤比稳态噪声严重。结论非稳态噪声、高频噪声引起的听力损伤比稳态/中、低频噪声引起的听力损伤严重。     

Numerical simulation of unsteady generalized Newtonian blood flow through differently shaped distensible arterial stenoses

An updated numerical simulation of unsteady generalized Newtonian blood flow through differently shaped distensible arterial stenoses is developed. A shear-thinning fluid modelling the deformation dependent viscosity of blood is considered for the characterization of generalized Newtonian behaviour of blood. The arterial model is treated as two-dimensional and axisymmetric with an outline of the stenosis obtained from a three-dimensional casting of a mildly stenosed artery. The full Navier-Stokes equations governing blood flow are written in the dimensionless form and the solution is accomplished by finite time-step advancement through their finite difference staggered grid representations. The marker and cell (MAC) method comprising the use of a set of marker particles moving with the fluid is used for the purpose. Results are obtained for three differently shaped stenoses – irregular, smooth and cosine curve representations. The present results do agree well with those of existing investigations in the steady state, but contrary to their conclusions the present findings demonstrate that the excess pressure drop across the cosine and the smooth stenoses is caused by neither their smoothness nor their higher degree of symmetry relative to the irregular stenosis, but is rather an effect of area cover with respect to the irregular stenosis. This effect clearly prevails throughout the entire physiological range of Reynolds numbers. Further the in-depth study in flow patterns reveals the development of flow separation zones in the diverging part of the stenosis towards the arterial wall, and they are influenced by non-Newtonian blood rheology, distensibility of the wall and flow unsteadiness in order to validate the applicability of the present model.     

Experimental and Numerical Investigation of an Axial Rotary Blood Pump

Left ventricular assist devices (LVADs) have become a standard therapy for patients with severe heart failure. As low blood trauma in LVADs is important for a good clinical outcome, the assessment of the fluid loads inside the pump is critical. More specifically, the flow features on the surfaces where the interaction between blood and artificial material happens is of great importance. Therefore, experimental data for the near‐wall flows in an axial rotary blood pump were collected and directly compared to computational fluid dynamic results. For this, the flow fields based on unsteady Reynolds‐averaged Navier–Stokes simulations‐computational fluid dynamics (URANS‐CFD) of an axial rotary blood pump were calculated and compared with experimental flow data at one typical state of operation in an enlarged model of the pump. The focus was set on the assessment of wall shear stresses (WSS) at the housing wall and rotor gap region by means of the wall‐particle image velocimetry technique, and the visualization of near‐wall flow structures on the inner pump surfaces by a paint erosion method. Additionally, maximum WSS and tip leakage volume flows were measured for 13 different states of operation. Good agreement between CFD and experimental data was found, which includes the location, magnitude, and direction of the maximum and minimum WSS and the presence of recirculation zones on the pump stators. The maximum WSS increased linearly with pressure head. They occurred at the upstream third of the impeller blades and exceeded the critical values with respect to hemolysis. Regions of very high shear stresses and recirculation zones could be identified and were in good agreement with simulations. URANS‐CFD, which is often used for pump performance and blood damage prediction, seems to be, therefore, a valid tool for the assessment of flow fields in axial rotary blood pumps. The magnitude of maximum WSS could be confirmed and were in the order of several hundred Pascal.     

Effect of Different Blood Cycle Modes on Mass Transfer of Artificial Kidney

INTRODUCTION Hollow fiber dialyzer has been widely applied to hemodialysis and chemicaldialysis process, and it is also called artificial kidney in medical science. There are ofgreat importance to improve the clinical dialysis efficiency by studying the masstransfer performance under different blood cycle modes in artificial kidney. Over the past decades, most models have been developed to describe transportphenomena in artificial kidney, the classical models are double-porous media model…     

系统电压30(36)以上至150(170)kV 挤包绝缘大长度交流海底电缆的推荐试验方法（译文）

为揭示多级压气机中上下游叶轮对中间叶片叠加气动影响特性,阐述不同叠加干涉情况下下游叶轮进气角度变化,采用数值方法模拟了一级轴流和一级离心组成的组合压气机非定常流场。详细讨论了上游动叶尾迹和下游动叶势流对中间导流叶栅段气流非定常流动的异频和同频叠加干涉特性,依据计算结果,直观地展示了静叶通道中两种干涉间相互激励和抑制作用的位置和时间,与数学公式的推导结果相互印证。研究结果表明:当上下游动叶对中间静叶段异频干涉时,干涉的激励、抑制区域的轴向位置随时间发生变化;当上下游动叶对中间静叶干涉频率相同时,干涉的相互激励、抑制区域的轴向位置不随时间发生变化,但干涉的激励、抑制区域的轴向位置受时序位置影响。另外,上游动叶尾迹与下游离心叶轮势流的不同叠加情况,决定着下游离心叶轮进口相对气流角的大小及波动幅值。      

血液热导率的瞬态热线法测试

基于无限大介质中的径向一维非稳态导热分析所确立的血液热导率的瞬态热线法原理和前期工作中存在的缺陷（１），对测试装置中的线热源，测温方法及检测技术等进行了改进，改善装置的性能，提高了测试的准确性，用正常人体的新鲜血液进行了测试，并对测试结果的不确定度作了分析，不确定度不超过２．５％。     

Computational fluid dynamics of left ventricular ejection

The present investigation addresses the effects of simple geometric variations on intraventricular ejection dynamics, by methods from computational fluid dynamics. It is an early step in incorporating more and more relevant characteristics of the ejection process, such as a continuously changing irregular geometry, in numerical simulations. We consider the effects of varying chamber eccentricities and outflow valve orifice-to-inner surface area ratios on instantaneous ejection gradients along the axis of symmetry of the left ventricle. The equation of motion for the streamfunction was discretized and solved iteratively with specified boundary conditions on a boundary-fitted adaptive grid, using an alternating-direction-implicit (ADI) algorithm. The unsteady aspects of the ejection process were subsequently introduced into the numerical simulation. It was shown that for given chamber volume and outflow orifice area, higher chamber eccentricities require higher ejection pressure gradients for the same velocity and local acceleration values at the aortic anulus than more spherical shapes. This finding is referable to the rise in local acceleration effects across the outflow axis. This is to be contrasted with the case of outflow orifice stenosis, in which it was shown that it is the convective acceleration effects that are intensified strongly.     

复方丹参滴丸治疗不稳定性心绞痛疗效观察

目的：观察中成药复方参滴丸治疗冠心病不稳定性心绞痛（属心血瘀阻证）的临床疗效。方法：采用随机对照法,在常规治疗基础上,治疗组38例使用复方丹参滴丸治疗。对照组35例使用硝酸异山梨醇酯片治疗,疗程均为4周。观察两组症状,前后我痛分级,心电图,血流动力学等变化。结果：治疗组总有效率为92．1％,对心绞痛分级,改善缺血心电图以及改善血液流变性等,与对照组比较,均有显性差异（P＜0．05,P＜0．001）,无不良反应,结论复方丹参滴丸对不稳定性心绞痛有较显疗效。     

Turbulence in pulsatile flows

Turbulence during pulsatile flow has been suggested as a possible mechanism to enchance the transport of gases during high-frequency ventilation. Experimental studies on oscillatory flow in straight, circular tubes have identified three types of flow: (a) laminar; (b) conditionally turbulent, in which high-frequency disturbances occur during the decelerating phase of the flow cycle but relaminarize by the beginning of the subsequent accelerating phase; and (c) fully turbulent flow, in which disturbances occur throughout the flow cycle. Fully turbulent flow has been observed only when a mean flow is present, and only laminar or conditionally turbulent flow has been observed for purely oscillatory flow. A critical Reynolds number based on the Stokes layer can be defined, and transition Reynolds numbers between 400 and 550 have been experimentally determined for purely oscillatory flow in a circular tube, although lower values are expected for physiological flows. There are some indications that the structure of oscillating turbulent flow is similar to steady turbulent flow, and preliminary work in our laboratory shows that the spectral content of flows during high-frequency ventilation is similar to that in steady turbulent flow.     

流室系统的流体动力学模拟

从Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程出发，运用无量纲化及虚宗量Ｂｅｓｓｅｌ函数法求解，导得流室系统中流体流动的速度场、切应力场等分布规律。并且，本文公式简化为常状态时，无论是和Ｃａｏ等人的理论结果，还是和他们的实验结果比较，都是相当一致的。