Separate assessment of porosity and uncombined carbon in cemented carbides

Porosity and uncombined carbon in cemented carbides are traditionally assessed by comparison to standardized microstructure charts, such as those in ISO 4505-1978. To improve the accuracy in the characterization a fully automatic image analysis procedure has been developed. The analysis is performed using light optical microscopy on unetched polished specimens. The implemented algorithm separates uncombined carbon, C-defects, from pores, A- and B-defects. Pores are approximately distributed in a random way in the structure. Uncombined carbon is on the other hand precipitated into clusters of carbon particles. This difference is together with defect size used as a base for the separation. Small defects situated close together are classified as C-defects, small isolated defects as A-pores and large defects as B-pores. Pores are found to be more round than the somewhat elongated C-defects. The difference in shape is significant and can also be used as a separation criterion.

Image analysis is used to quantitatively characterise the ISO 4505-1978 standard charts with respect to volume fraction, number density and size distribution of defects. The results are compared to measured distributions for true microstructures.     

Composition Dependence and Irradation Effects on Residual Resistivity in Cu-Al Alloys

Residual electrical resistivity due to short-range order has been calculated for Cu100-xAlx (x=9.13,13.56, 14.5 and 14.76 in at pct) alloys using pseudopotential approach, and the results have been discussed in the light of experimental studies of the local-order structure of these alloys. In case of Cu85.5Al14.5, change in the total residual electrical resistivity due to neutron-irradiation effects has been estimated by including contributions from the short-range order and static atomic displacement correction. Our results show a decrease in the residual resistivity in the irradiated Cu-Al solid solution as compared to the unirradiated sample. This is in accordance with the experimental results     

Analysis of thin walled structures using the boundary element method

In this article the direct boundary element formulations of stretching and bending plate problems are combined together to solve thin walled structures and other similar frames. The final system is obtained by assuming each individual plane structural element as a subregion. After the necessary transforms of these equations they can be combined together taking into account the displacement compatibility and equilibrium conditions.     

Experimental densities for compressed R134a

This paper reports densities of compressed R134a (1,1,1,2-tetrafluoroethane) determined by using a contiuously weighed pycnometer at 20 K intervals between 180 and 380 K at pressures from slightly greater than the vapour pressure to 70 MPa. The results are accurate to within ±0.1%. Saturated liquid densities derived by extrapolation from the experimental values agree with other reported values to within ±0.3%.     

Depth of intergranular oxygen diffusion during environment-dependent fatigue crack growth in alloy 718

The elevated-temperture fatigue crack growth behavior in alloy 718, when subjected to a loading frequency lower than the transitional frequency of this alloy, is viewed as fully environment dependent. In this process, the crack growth increment per loading cycle is assumed to be equal to the intergranular oxygen diffusion depth at the crack tip during the cycle effective oxidation time. In order to identify the trend of this diffusion depth an experimental program was carried out on compact tension specimens made of alloy 718 at 650 °C in which fatigue crack growth measurements were made for cyclic load conditions with and without hold time periods at minimum load level. This work resulted in establishing a relationship correlating the intergranular oxygen diffusion depth and the value of the stress intensity factor range ΔK. This relationship, when integrated over the cycle effective oxidation time, results in a closed-form solution describing the environment-dependent fatigue crack growth rate. A comparison is made between the results of this solution when applied to different loading frequencies and the corresponding experimental results. This comparison shows good agreement between the two sets of results. Furthermore, by combining the parabolic rate law of diffusion and the equation for the intergranular oxygen diffusion depth, an explicit expression for the oxygen diffusivity of grain boundaries is derived. It is found that this diffusivity is both a ΔK- and a frequency-dependent parameter.     

最佳基数排序

基数排序由于其效率高而被广泛应用。通常,基数排序所用的基数是10,然而,如果求得一个基数r_(best),并且用r_(best)为基数进行基数排序使排序时间达到最小,则这将具有非常重要的意义。本文给出了求r_(best)的方法,分析了以r_(best)为基数进行基数排序的时间复杂度,提出了进一步提高效率的措施,并将以r_(best)为基数的基数排序速度与以10为基数的基数排序进行了比较。     

Cost Effective VLSI Architectures for Full-Search Block-Matching Motion Estimation Algorithm

In this paper, we present efficient VLSI architectures for full-search block-matching motion estimation (BMME) algorithm. Given a search range, we partition it into sub-search arrays called tiles. By fully exploiting data dependency within a tile, efficient VLSI architectures can be obtained. Using the proposed VLSI architectures, all the block-matchings in a tile can be processed in parallel. All the tiles within a search range can be processed serially or concurrently depending on various requirements. With the consideration of processing speed, hardware cost, and I/O bandwidth, the optimal tile size for a specific video application is analyzed. By partitioning a search range into tiles with appropriate size, flexible VLSI designs with different throughput can be obtained. In this way, cost effective VLSI designs for a wide range of video applications, from H.261 to HDTV, can be achieved.     

原料扩重的中压加氢改质装置投产

介绍燕山石化公司为扩大1Mt／a中压加氢改质装置的原料来源，改用大庆减二线油和重油催化裂化柴油组成的混合料开工投产的经验以及装置初期的运行条件。中压加氢改质技术可以生产优质柴油和蒸汽裂解制乙烯的原料，还可增产喷气燃料。     

TNT-RDX混合废水处理的实验研究——生物-吸附法

介绍了在２５￣３５℃的温度下，用厌氧－兼氧－水生生物－吸附组合工艺处理ＴＮＴ和ＲＤＸ混合废水的方法，进行了日处理量为６０￣９００Ｌ的实验室放大实验。当ＴＮＴ和ＲＤＸ混合废水总浓度为４￣１２ｍｇ／Ｌ时，经过该工艺处理后可达到国家排放标准。其中厌氧－兼氧能去除废水中８０％以上的ＴＮＴ和ＲＤＸ，水生生物（水葫芦）对ＴＮＴ及ＲＤＸ也有一定的降解效果，最后用活性炭吸附可以实现深度处理。