Abstract MPEG TRANSCODING FOR DVD RECORDING

In this paper a system level MPEG transcoding scheme is proposed. The MPEG-2 system standard specifies two kinds of streams: transport stream (TS) and program stream (PS). Each is optimized for a different set of applications. The transcoding between TS and PS has an important application, which can be applied to convert the digital television (DTV) broadcasting bitstreams to the bitstreams for digital video disc (DVD) application. An important technical issue for transcoding between PS and TS is the rate control algorithm. Usually, for DVD application, the video is encoded by variable bit rate (VBR) in order to provide constant quality over whole sequence, while for DTV application due to buffer requirement the video should be encoded by constant bit rate (CBR). In this paper, a novel VBR rate control algorithm is proposed for the on-line video transcoding process. In this algorithm, the bit allocation strategy at picture level, which is based on a bit producing model and hyperbolic R-Q function, is first discussed. Then, the rate control algorithm at macroblock level with R-D optimization is proposed. Experiment results show that the proposed VBR transcoding algorithm achieved the better image quality compared with CBR transcoding at the same bit rate. 1

Application Research on Liner Tube without Variable Diameter of Shale Gas Plunger Gas Lift Wellhead

Given that there is variable diameter in the shale gas plunger gas lift wellhead, which causes that the plunger cannot run up and down the gas well wellhead, affects the effect of plunger drainage gas production, the paper carries out research on liner tube without variable diameter of the shale gas plunger gas lift wellhead and installation methods, makes the diameter of the gas well wellhead consistent with that of the oil pipe, ensure that the plunger can be open up and down the wellhead of the Christmas tree, facilitate the periodic inspection and replacement operation of the plunger, and reduces the cost of plunger salvage operations. The successful application of the process plan in the shale gas well ** has achieved good drainage gas production effect, truly solved the variable diameter problem of shale gas plunger gas lift wellhead, and achieved the goal of once and for all

A numerical study on the lateral loading behaviour of offshore tetrapod piled jacket foundations in clay

Jacket foundations for offshore wind turbines, typically having three or four latticework legs, are mainly subjected to lateral loads induced by winds, waves and currents during their service life. An accurate assessment of the bearing capacity of these foundations is of great importance in the design. This paper presents a study into the monotonic lateral loading behavior of tetrapod piled jacket foundations in undrained clay, with the complex lateral loads being simplified to an equivalent lateral load acting at a certain height of the jacket. A centrifuge testing programme was undertaken to provide high-quality validation data for the development of a three-dimensional finite element model established using ABAQUS. The key parameters investigated are the spacing and embedment of the piles, the height to which the equivalent lateral load acts and the angle between the direction of this load and the orthogonal line of the jacket in the horizontal plane. The parametric study aims to provide guidance to the optimal design of jacket piled foundations: for instance, to examine the critical pile embedment beyond which limited improvement of the bearing capacity of the foundation can be achieved and to define the most unfavorable lateral loading direction. In addition, the limitations of the commonly assumed constant p-multiplier, regardless of the lateral deflection of the pile and the depth along it, are critically discussed. Then an improved analytical model is proposed, based on the existing model used in design and the parametric study results, to quantify the variation of p-multiplier with depth and with pile deflection

An experimental study on the lateral pile–soil interaction of offshore tetrapod piled jacket foundations in sand

Recently, tetrapod piled jacket (TPJ) foundations have shown considerable promise in offshore developments, due to the increases in power capacity and water depth for offshore wind turbines. This paper presents a set of centrifuge tests to look into the lateral loading behaviour of TPJ foundations in sand, with the overall load–displacement responses of the foundation as well as the soil resistance and internal forces on or within individual piles being examined carefully. Test results show that the back-row piles are more likely to be pulled out when the TPJ foundation is loaded laterally along the diagonal direction compared to when loaded along the orthogonal direction. The lateral soil resistance per unit length on the back-row pile(s) is approximately 60% of that on the front-row one(s) in the orthogonal loading case, and only about 40% in the diagonal loading case. Moreover, although the TPJ foundation is in its form a special case of pile groups, it is highlighted in the present study that the former case exhibits distinct loading behaviour from the latter case due to the typically large overturning moment encountered by the foundations for offshore wind turbines. Finally, the p-multipliers of the piles are demonstrated to be dependent on pile deflections, but independent on soil depths, and as a result, a modified pm model is proposed to provide guidance for the design of TPJ foundations in sand.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Land surface temperature and its impact factors in Western Sichuan Plateau, China

The understanding influence of multiple factors variations on land surface temperature (LST) remains elusive. LST was retrieved by the atmospheric correction algorithms. Based on the correlation coefficients, stepwise regression analysis was developed to examine how multiple factors variability led to LST variations. The differences in LST between impact factors vary depending on time in a day. The elevation and land use types significantly affect the LST in sunny slope or shadow areas has a significantly quadratic curve correlation or a negative linear correlation with it, the influence of slope and aspect is not very significant. LST for forestland, grassland and bare land in the sunny slope and shadow area was the cubic polynomial related to its elevation. Normalized difference vegetation index (NDVI) and normalized difference moisture index (NDMI) effectively express LST in mountainous. LST and NDMI or NDVI have a significantly negative correlation, NDMI is more effective and more applicable for the expression of LST

Experimental study on lateral pile–soil interaction of offshore tetrapod piled jacket foundations in sand

Recently, tetrapod piled jacket (TPJ) foundations have shown considerable promise in offshore developments, due to the increases in power capacity and water depth for offshore wind turbines. This paper presents a set of centrifuge tests to look into the lateral loading behaviour of TPJ foundations in sand, with the overall load–displacement responses of the foundation as well as the soil resistance and internal forces on or within individual piles being examined carefully. Test results show that the back-row piles are more likely to be pulled out when the TPJ foundation is loaded laterally along the diagonal direction compared to when loaded along the orthogonal direction. The lateral soil resistance per unit length on the back-row pile(s) is approximately 60% of that on the front-row one(s) in the orthogonal loading case, and only about 40% in the diagonal loading case. Moreover, although the TPJ foundation is in its form a special case of pile groups, it is highlighted in the present study that the former case exhibits distinct loading behaviour from the latter case due to the typically large overturning moment encountered by the foundations for offshore wind turbines. Finally, the p-multipliers of the piles are demonstrated to be dependent on pile deflections, but independent on soil depths, and as a result, a modified pm model is proposed to provide guidance for the design of TPJ foundations in sand