Risk assessment and ventilation modeling for hydrogen releases in vehicle repair garages

The availability of repair garage infrastructure for hydrogen fuel cell vehicles is becoming increasingly important for future industry growth. Ventilation requirements for hydrogen fuel cell vehicles can affect both retrofitted and purpose-built repair garages and the costs associated with these requirements can be significant. A hazard and operability (HAZOP) study was performed to identify risk-significant scenarios related to light-duty hydrogen vehicles in a repair garage. Detailed simulations and modeling were performed using appropriate computational tools to estimate the location, behavior, and severity of hydrogen release based on key HAZOP scenarios. This work compares current fire code requirements to an alternate ventilation strategy to further reduce potential hazardous conditions. Modeling shows that position, direction, and velocity of ventilation have a significant impact on the amount of instantaneous flammable mass in the domain.     

Magnetohydrodynamic Effect on Free Convection of Three Dimensional Laminar Flow in Porous Annulus

A numerical study has been carried out to investigate heat transfer by free convection under the effect of MHD （magnetohydrodynamic） for steady state three-dimensional laminar flow in horizontal and vertical cylindrical annulus filled with saturated porous media （sand silica） with fins attached to the inner cylinder. A single electric coil placed around the inner cylinder to generate a magnetic field. The governing equations which used are continuity, momentum （using Darcy＇s law） and energy equations which are transformed to dimensionless equations. The finite difference approach is used to obtain all the computational results using Fortran 90 program. The parameters affected on the system are Rayleigh number ranging within （102 ~ Ra＊ 〈 104）, and MHD （Mn） （0 〈_ Mn 〈_ 100） and radius ratio Rr （0.225, 0.338 and 0.435）. The results obtained are presented graphically in the form of streamline and isotherm contour plots and the results show that heat transfer decrease with the increase of magnetohydrodynamic. It was found that the average Nusselt number increase with Ra＊ and decrease with H~ Mn and Rr. A correlation for the average Nusselt number in terms of Ra＊ and Mn, has been developed for the inner cylinder.     

Evaluation of a new composite prosthesis for the repair of abdominal wall defects

The degree of integration of biomaterials used in the repair of abdominal wall defects seems to depend upon the structure of the prosthesis. The present investigation evaluates the behaviour in terms of adhesion formation and integration of a new composite prosthesis that could be employed in this clinical application. Full-thickness abdominal wall defects (7 × 5 cm) were created in 16 anaesthetized New Zealand white rabbits and the prosthesis were placed in direct contact with the visceral peritoneum during the experiment. The defects were repaired with a composite prosthesis or pure polypropylene mesh to establish two study groups (n = 8 each). The composite device was constituted by a polypropylene mesh physically attached to a poly(ether)urethane–polydimethylsiloxane laminar sheet. Animals were sacrificed 7, 14, 21 and 30 days after implant and prosthesis/surrounding tissue specimens subjected to light and electron microscopy. Firm adhesions were detected in the polypropylene implants, while they were not present in the composite implants. The excellent behaviour of the composite prosthesis shown in this study warrants further investigation on its use for the repair of abdominal wall defects when a prosthetic device needs to be placed in contact with the intestinal loops.     

Risk Assessment of Hydrogen Fuel Cell Electric Vehicles in Tunnels

The need to understand the risks and implications of traffic incidents involving hydrogen fuel cell electric vehicles in tunnels is increasing in importance with higher numbers of these vehicles being deployed. A risk analysis was performed to capture potential scenarios that could occur in the event of a crash and provide a quantitative calculation for the probability of each scenario occurring, with a qualitative categorization of possible consequences. The risk analysis was structured using an event sequence diagram with probability distributions on each event in the tree and random sampling was used to estimate resulting probability distributions for each end-state scenario. The most likely consequence of a crash is no additional hazard from the hydrogen fuel (98.1–99.9% probability) beyond the existing hazards in a vehicle crash, although some factors need additional data and study to validate. These scenarios include minor crashes with no release or ignition of hydrogen. When the hydrogen does ignite, it is most likely a jet flame from the pressure relief device release due to a hydrocarbon fire (0.03–1.8% probability). This work represents a detailed assessment of the state-of-knowledge of the likelihood associated with various vehicle crash scenarios. This is used in an event sequence framework with uncertainty propagation to estimate uncertainty around the probability of each scenario occurring.     

虚拟镜像光盘网络服务器的设计与实现

提出并实现了一种具有较高性能价格比的、基于PC的虚拟镜像光盘网络服务器方案。该虚拟光盘网络服务器具有如下优点：支持多种格式盘片的镜像读取;支持多种网络协议;虚拟光盘镜像服务器在功能上完全独立于网络上的主服务器;价格低廉,无须特殊硬件等。初步实验验证了该方案的可行性。由于该方案具有很好的应用前景,正准备将其推向市场。     

Techno-economic analysis of microsystem based hybrid energy combination for island application

Microsystem Technologies - The analysis of hybrid PV/diesel/storage energy system in southern island of the province of South Leyte, Philippines is presented in this paper. Appropriate selection of...     

Effect of plasticization on the photodegradation of poly (para-methoxystyrene) films

The influence of dibutyl phthalate, dioctyl phthalate, dimethyl terephthalate, diethyl terephthalate, and dioctyl terephthalate-plasticizers on poly (para-methoxy styrene) photodegradation was investigated by UV–vis, fluorescence, and FT-IR spectroscopic methods. The increase in irradiation time caused an increase in the absorption band of the polymer and an increase in the absorption of new band at longer wavelength, thus indicating a possibility of photodegradation of polymer films. The study on poly (para-methoxy styrene) photodegradation was also compared to varying phthalate and terephthalate plasticizers in order to provide an understanding of its photodegradation vis the presence of phthalates and terephthalates plasticizers. The decrease in the excimer fluorescence upon the increase in the time of exposure to UV-radiation provides an evidence for the degradation of polymeric chains through a chin scission processes. The increase in the photodegradation of the polymer increased with the increase in the bulkiness of added plasticizer molecule. IR-spectra of irradiated pure and blended polymer films indicated that the photodegradation of the polymer occurred, by the formation of new absorption bands, and the increase in the intensity of other bands.