Numerical Analysis of Mechanical Phenomena in Coronary Stent Made of Titanium Alloy Ti-13Nb-13Zr

Using the finite element method, this study determined mechanical characteristics of slotted-tube stents. The numerical calculations were carried out using ADINA v.8.8 software. Three models with different number of segments were used. The analysis was carried out for the titanium-matrix alloys Ti-13Nb-13Zr. Assuming the actual conditions of stent implantation, the stent is expected to expand to the diameter of 3.0 mm i.e. until it reaches the internal diameter of a healthy coronary vessel. The effect of the stent geometry was analysed, with emphasis on examination of the effect of key mechanical phenomena such as expansion pressure and suitable level of stress and plastic strain in stents. Analysis of the degree of foreshortening and dogboning after stent expansion was also carried out. The following assumptions were adopted in order to determine mechanical properties of stents: implantation at low expansion pressure, limitation of foreshortening ≤ 2%, low increase in the implant diameter in the beginning and at the end of the stent (dogboning effect).

Volume-controlled mechanical ventilation

The goal of mechanical ventilation is to achieve adequate gas exchange while minimizing haemodynamic compromise and ventilator-associated lung injury. Volume-controlled ventilation can be delivered via several modes, including controlled mechanical ventilation, assist control (AC) and synchronized intermittent mandatory ventilation (SIMV). .In volume-controlled modes, the clinician sets the flow pattern, flow rate, trigger sensitivity, tidal volume, respiratory rate, positive end-expiratory pressure, and fraction of inspired oxygen. Patient ventilator synchrony can be enhanced by setting appropriate trigger sensitivity and inspiratory flow rate. I:E ratio can be adjusted to improve oxygenation, avoid air trapping and enhance patient comfort. There is little data regarding the benefits of one volume-controlled mode over another. In acute respiratory distress syndrome, low tidal volume ventilation in conjunction with plateau pressure limitation should be employed as there is a reduction in mortality with this strategy. This chapter addresses respiratory mechanics, modes and settings, clinical applications, and limitations of volume-controlled ventilation.

Division method for water distribution networks in hilly areas

Water distribution systems in hilly areas are always divided into several zones due to the undulating terrain. The present approach of dividing water distribution systems lacks an assessment index and is characterized by a low degree of automation. With the building of a mathematical model, this paper introduces two indicators – pressure limitation and pressure variation – to enable the automatic division of the water supply pipe network. It prioritizes economic index as the objective function in the evaluation of the division of water distribution systems in hilly areas, and then selects the optimal division scheme by generic algorithm in a large number of candidates. The SY terrain in YW City China is used for verification. Compared to traditional water supply partition methods, this procedure is easier to operate time-savingly by staff and is more automatic.

Braking Solution for a Hydraulically Driven Linear Pallet Changer Mechanism

The use of machining centres is predominant in the case of small and medium size batch manufacturing, their advantages being materialised in high productivity. The productivity is owed, mainly, to the small auxiliary times consumed with the tool and material change, times which are served by the automatic tool changer system and the automatic pallet changer. The purpose of this article researches aims to determine the kinematic parameters of an hydraulically driven linear pallet changer in two cases (when the deceleration is carried out through a throttle and when the deceleration is made through a new solution). Thus, an experimental set-up, which matches an hydraulically driven linear pallet changer, was designed and built. The experiments aimed toward using a classic braking method of hydraulic cylinders and a new two-stage braking with counter-pressure limitation.

Parameters Study of Deep Water Subsea Pipeline Selection

Recent developments in offshore pipeline projects in Malaysia waters are showing general trend towards deeper water, such as KIKEH in 2200 meter water depth. As the exploration is getting into deeper water or crossing a deep water section, different design issues may become governing compared to shallow water. Conceptual Design for Deep Water Pipeline discusses number of issues that need to be taken onto account in the design of pipelines in deep water. Aspect related to high external pressure, limitation for installation and geo-hazards are addressed. In order to give an early insight for designer to measure the reliability for a deep water project to current technology capabilities, a simulation program required to achieve the objective. This paper discusses several factors for selection of subsea pipelines such as wall thickness, buckling arrestors design, installation configuration and free spanning.

Energy and Exergy Analysis for Three Type 500MW Steam Power Plants

The paper shows the comparison of energy and exergy analysis of thermal power plants based on advanced steam parameters in China climatic conditions. The research contains coal-based thermal power plants using sub-critical, super-critical, and ultra-supercritical steam conditions. The design configurations of 500 MW unit size were considered. The research contains the effect of condenser pressure on plant and exergy efficiency. The effect of high grade coal on performance parameters as compared to typical China low grade coal was also studied. The major exergy loss took place in coal combustion followed by the steam generator. Due to condenser pressure limitation, the maximum possible overall energy efficiency was found to be about 44.4% with the ultra-supercritical power plant. Installing coal-based thermal power plants based on advanced steam parameters in China will be a prospective option aiding energy self-sufficiency.