We present an overview of some recent developments in the area of mathematical modeling of maintenance decisions for multi-unit systems. The emphasis is on three main groups of multicomponent maintenance optimization ...We present an overview of some recent developments in the area of mathematical modeling of maintenance decisions for multi-unit systems. The emphasis is on three main groups of multicomponent maintenance optimization models： the block replacement models, group maintenance models, and opportunistic maintenance models. Moreover, an example of a two-unit system maintenance process is provided in order to compare various maintenance policies.展开更多
Static-type samplers are required for sampling corrosive, toxic, high-temperature, or radioactive liquid-solid fluids. We have designed a compact reverse flow diverter pumping system for transferring liquid-solid mixt...Static-type samplers are required for sampling corrosive, toxic, high-temperature, or radioactive liquid-solid fluids. We have designed a compact reverse flow diverter pumping system for transferring liquid-solid mixtures. In accordance with the Venturi principle, an acceptable volume of liquid-solid fluid is automatically collected into a sampling bottle. The effects of sampling needle sizes, sectional area of the T-section, solid concentration, and liquid viscosity on the performance of fluidic samplers were experi- mentally investigated. The sample volume increased upon the reduction of the sampling needle length and the increase of the sectional area of the T-section, but decreased with the increase of solid concentration and liquid viscosity. Unbiased samples of acceptable volume were produced by the proposed fluidic sampler, even at 10.21 mPa s liquid viscosity, 35 wt% solid concentration, and 6.74 m sampling height.展开更多
文摘We present an overview of some recent developments in the area of mathematical modeling of maintenance decisions for multi-unit systems. The emphasis is on three main groups of multicomponent maintenance optimization models： the block replacement models, group maintenance models, and opportunistic maintenance models. Moreover, an example of a two-unit system maintenance process is provided in order to compare various maintenance policies.
文摘Static-type samplers are required for sampling corrosive, toxic, high-temperature, or radioactive liquid-solid fluids. We have designed a compact reverse flow diverter pumping system for transferring liquid-solid mixtures. In accordance with the Venturi principle, an acceptable volume of liquid-solid fluid is automatically collected into a sampling bottle. The effects of sampling needle sizes, sectional area of the T-section, solid concentration, and liquid viscosity on the performance of fluidic samplers were experi- mentally investigated. The sample volume increased upon the reduction of the sampling needle length and the increase of the sectional area of the T-section, but decreased with the increase of solid concentration and liquid viscosity. Unbiased samples of acceptable volume were produced by the proposed fluidic sampler, even at 10.21 mPa s liquid viscosity, 35 wt% solid concentration, and 6.74 m sampling height.
