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991.
埕东油田西区南块整体堵水中堵剂的研究和应用 总被引:1,自引:0,他引:1
本文介绍了埕东油田西区南块整体堵水中堵剂的研究和应用,包括对单液法铬冻胶的评价和改进、沉淀型双液法堵剂的筛选、将铬冻胶改为双液法堵剂、锆冻胶的引进和堵漏剂的使用等。在试验期间按堵水方案向区块投入上述各类堵剂11267m3,使区块的年含水量控制在2%以下,增产原油29600t。 相似文献
992.
文章介绍了目前国内外长输管道外防护技术的特点和防护层应用的现状,分析了常用防腐蚀材料的防腐蚀性能。指出在山区复杂地形条件下,应考虑环境条件和施工条件,并通过技术经济分析对管道外防腐蚀层进行合理选择。 相似文献
993.
Determination of Boundary Shear Stress and Reynolds Shear Stress in Smooth Rectangular Channel Flows 总被引:1,自引:0,他引:1
A method for computing three-dimensional Reynolds shear stresses and boundary shear stress distribution in smooth rectangular channels is developed by applying an order of magnitude analysis to integrate the Reynolds equations. A simplified relationship between the lateral and vertical terms is hypothesized for which the Reynolds equations become solvable. This relationship has the form of a power law with an exponent of n = 1, 2, or infinity. The semiempirical equations for the boundary shear distribution and the distribution of Reynolds shear stresses are compared with measured data in open channels. The power-law exponent of 2 gave the best overall results while n=infinity gave good results near the boundary. 相似文献
994.
采用高功率射频信号内部互调失真的包络特性检测与比较技术,对射频功率带外信号进行检测和估计。设计用于高功率射频放大器前馈技术线性化的一个带外信号检测器。探讨如何进行射频载波抵消以及检测放大器互调失真信号。 相似文献
995.
Zhang X.B. Lam S.S. Dong-Young Lee Yang Y.R. 《Networking, IEEE/ACM Transactions on》2003,11(6):908-922
We present the design and specification of a protocol for scalable and reliable group rekeying together with performance evaluation results. The protocol is based upon the use of key trees for secure groups and periodic batch rekeying. At the beginning of each rekey interval, the key server sends a rekey message to all users consisting of encrypted new keys (encryptions, in short) carried in a sequence of packets. We present a scheme for identifying keys, encryptions, and users, and a key assignment algorithm that ensures that the encryptions needed by a user are in the same packet. Our protocol provides reliable delivery of new keys to all users eventually. It also attempts to deliver new keys to all users with a high probability by the end of the rekey interval. For each rekey message, the protocol runs in two steps: a multicast step followed by a unicast step. Proactive forward error correction (FEC) multicast is used to reduce delivery latency. Our experiments show that a small FEC block size can be used to reduce encoding time at the server without increasing server bandwidth overhead. Early transition to unicast, after at most two multicast rounds, further reduces the worst-case delivery latency as well as user bandwidth requirement. The key server adaptively adjusts the proactivity factor based upon past feedback information; our experiments show that the number of NACKs after a multicast round can be effectively controlled around a target number. Throughout the protocol design, we strive to minimize processing and bandwidth requirements for both the key server and users. 相似文献
996.
997.
998.
Evaluating Liquefaction Strength of Partially Saturated Sand 总被引:1,自引:0,他引:1
A method is presented for evaluating the liquefaction strength of partially saturated sand using the compression wave velocity (P-wave velocity), a new indicator of saturation. Based on laboratory test results, an empirical correlation that relates the liquefaction strength with the pore pressure coefficient B is firstly proposed. The strength is defined as the cyclic stress ratio required to cause liquefaction at a specified number of cycles. With the aid of a theoretical relation between B and the P-wave velocity, an explicit correlation of more interest is then established between the liquefaction strength of sand and its P-wave velocity. A comparison of the predictions using this explicit correlation with laboratory measurements shows a satisfactory agreement. The significance of this method lies in that it makes it possible to evaluate the liquefaction strength of sand as affected by saturation through the measurement of P-wave velocity, which can be made not only in the laboratory but particularly in the field. 相似文献
999.
1000.
铝基印制电路板制造工艺研究 总被引:1,自引:0,他引:1
此文对一种进口铝基印制电路板的制造工艺流程进行了介绍,对所采用的制造工艺技术进行了较为详细的论述。 相似文献