Design and Experiment for Exhaust Pipes of Pressure Wave Supercharged Diesel Engine

NOx and soot emissions from diesel engines can be greatly reduced by pressure wave supercharging （PWS）. The diesel engine matched with PWS needs redesigning its exhaust pipes. Except for meeting the installation requirements, the exhaust gas must be stable in pressure before rushing into PWS. In this paper the lateral and center ported divergent exhaust pipes are designed, modeled geometrically and analyzed structurally based on a 3-D design software-CATIA to determine the structure of two exhaust pipes having the required inner volume. Then flow analysis for two exhaust pipes is done using a flow analysis software-ANASYS. Moreover, the optimal exhaust pipes are determined comprehensively and cast for engine test. Engine test results show that PWS is superior to turbocharging at low engine speeds and inferior to turbocharging in power and emissions at medium-to-high engine speeds. The performance of PWS engine under high speed operating conditions can be improved by contriving larger surge volume intake and exhaust nines.     

The Short Wave Aerostat-Mounted Imager (SWAMI): A novel platform for acquiring remotely sensed data from a tethered balloon

We describe a new remote sensing system called the Short Wave Aerostat-Mounted Imager (SWAMI). The SWAMI is designed to acquire co-located video imagery and hyperspectral data to study basic remote sensing questions and to link landscape level trace gas fluxes with spatially and temporally appropriate spectral observations. The SWAMI can fly at altitudes up to 2 km above ground level to bridge the spatial gap between radiometric measurements collected near the surface and those acquired by other aircraft or satellites. The SWAMI platform consists of a dual channel hyperspectral spectroradiometer, video camera, GPS, thermal infrared sensor, and several meteorological and control sensors. All SWAMI functions (e.g. data acquisition and sensor pointing) can be controlled from the ground via wireless transmission. Sample data from the sampling platform are presented, along with several potential scientific applications of SWAMI data.     

Effect of waves on the tidal energy resource at a planned tidal stream array

Wave–current interaction (WCI) processes can potentially alter tidal currents, and consequently affect the tidal stream resource at wave exposed sites. In this research, a high resolution coupled wave-tide model of a proposed tidal stream array has been developed. We investigated the effect of WCI processes on the tidal resource of the site for typical dominant wave scenarios of the region. We have implemented a simplified method to include the effect of waves on bottom friction. The results show that as a consequence of the combined effects of the wave radiation stresses and enhanced bottom friction, the tidal energy resource can be reduced by up to 20% and 15%, for extreme and mean winter wave scenarios, respectively. Whilst this study assessed the impact for a site relatively exposed to waves, the magnitude of this effect is variable depending on the wave climate of a region, and is expected to be different, particularly, in sites which are more exposed to waves. Such effects can be investigated in detail in future studies using a similar procedure to that presented here. It was also shown that the wind generated currents due to wind shear stress can alter the distribution of this effect.     

Wave energy assessment in Sicily (Italy)

This research presents an estimation of wave energy potential in Sicily (Italy) carried out using both buoy wave measurements from Rete Ondametrica Nazionale (RON), the Italian Government wave buoy network, and wave parameter data by ERA-INTERIM, a recent meteorological reanalysis project of the European Centre for Medium-Range Weather Forecasts (ECMWF). Starting from these offshore data, we first identified the western part of Sicily as the area with a higher availability of offshore wave energy; subsequently, we selected a study area in the western part of the south coast and assessed the nearshore potential energy by performing propagation using a spectral model (SWAN). The nearshore analysis highlights the presence of a “hot spot” relatively close to the coast where energy concentration produces even higher energy availability than offshore. Based on this result, the site may be a possible location for a wave energy farm, provisional on a technical–economic feasibility analysis.     

Optimal control of the wave propagation problem with the extended conjugate gradient method

Thus paper formulates and solves an optimal control problem subject to the wave propagation equation, employing the Extended Conjugate Gradient Method (ECGM). New optimal state and control solutions were obtained with their surface plots.     

摇板式造波机生成的长峰规则波

利用特征函数展开法对摇板式造波机作周期运动生成的长峰规则波流场作了二阶分析,得到了速度势和波形二阶解的解析表达式.通过对二阶波传播模式的分析,确定造波机响应特性曲线(一阶波幅摇幅比)和规则波最大波高曲线,给出能在水池中生成二阶意义上纯正的Stokes波的造波机运动形式.上述有关造波特性的理论分析是研制造波软件,确保在水池中生成高品质Stokes波的基础,具有重要的应用价值.