Ultra-high molecular-weight polyethylene (UHMWPE) has been used in total hip replacement for the last three decades. Despite the advancements in prosthesis design, the wear of UHMWPE remains a serious clinical problem; the release of wear debris may induce osteolysis and implant loosening. Understanding of wear behavior and wear debris morphology of the polyethylene is essential to improve the reliability of hip joint implants. The investigation in this paper carried out wear simulation tests of UHMWPE on Al2O3, 316L stainless steel, CoCrMo alloy and Ti6Al4V alloy, respectively. The lubrication of plasma solution and bovine serum solution was presented in wear tests. The effect of motion and loading on the wear behavior and wear debris morphology, and the influence of femoral head material and assembly style were studied in order to obtain a better understanding of the morphology of ultra-high molecular weight polyethylene wear particles. It is shown that the wear of UHMWPE acetabular cups against metal femoral heads was significantly higher than that against ceramic heads. The presence of protein in lubricant increases the wear of UHMWPE acetabular cups on Al2O3 heads. The wear rates of UHMWPE in multi-directional motion are approximately 2.5 times of those in uni-directional motion. The size distribution range of the UHMWPE debris particles for all head materials varies from submicron particles up to several hundreds micron. The size distribution range of wear debris particles is not directly related to wear resistance of UHMWPE, but significantly influenced by wear mechanisms. The UHMWPE debris particles produced in hip wear simulation tests are classified as round debris, flake-like debris and stick debris, which are closely related to the primary mechanisms of abrasive wear, adhesive wear and fatigue wear.

Low frequency oscillation caused by system interconnection has been the main factor to threat the secure operation of power grid. It’s significant to research on the problem of low frequency oscillation. This paper summarizes the generation mechanism and analysis methods of low frequency oscillation. Each analysis method has both advantages and disadvantages.

When mining close-distance seams with downlink mining, in order to benefit roof maintenance and management, the decoration of lower seam roadways should try to avoid the area affected by pillar concentrated stress , using inside cross decorationg; In order to improve the recovery rate of resources, the size of protection pillar can’t be too big, when mining under pillar of upper layer and mining in pillar of upper layer with crossing. The whole lower face or some phase located under the influence of upper coal concentration stress, give roadways and working face roof maintenance a lot of difficulties. Then it appeared the conflict between security and economy, to solve this problem, we must return to the correct understanding of mine pressure behave law. In the paper, through the investigation of the typical dozen example in mining of face the coal pillar in China, to get its regular pattern of mine pressure behave, in similar conditions mining, there will be important reference and guidance.

32/28nm BEOL Cu CMP process with ultra low k scheme is investigated in the different aspects. Firstly the barrier metal (BM) slurry selection with proper selectivity is the most critical part to reduce topography. The topography can be minimized by precisely control BM slurry’s selectivity. Secondly, the layout design, such as pattern density, line and space width, has significant impact on WID variation. The test results show more topography correction at more dense Cu line for thinner line where BM polishing is the dominate factor. While for fat line, it shows less topography correction at more dense Cu line, since Cu clearance polishing dominates the final topography. Next k value shift evaluation with different barrier metal slurry, cleaning chemicals and post CMP thermal treatment conditions is also studied. The results indicate that although k value shift occurs during polishing, proper chemicals clean and post thermal treatment can restore parts even the whole of k shift. In addition, the removal of moisture and chemical penetrated into ultra low k film is the key of k value shift and reliabilities improvement.

The formidable and multivariate coal-mining conditions during the production often lead to various improper damage and inactivation of guide foot. Wear is the most severe problem. We do the research on optimization design of the materials by plasma cladding technic to improve the wear resistance: The Cr28MnV ferrous alloy overlay was deposited on the surface of 45# tempered steel backing. The martensitic structure with high strength, high hardness, and high abradability evenly distributed alloy carbide can be gained after cooling the overlay. The combined backing has a good obdurability which can satisfy the requirement of coal mine complex conditions after modifying treatment.