基于相关法的低采样率超声水表时延估计方法

针对当前超声水表中相关法时间分辨率只能达到采样周期的问题,提出了一种基于相关法的低采样率超声水表时延估计方法.首先,研究了超声水表中所能达到的最大时间延迟;其次,讨论了相关法在超声水表当中的具体应用及插值算法对于提高流量测量精度的作用;最后,利用MATLAB软件对算法进行仿真评估了实际噪声条件下算法能达到的时延估计精度并搭建流量计量系统证明算法的有效性.仿真结果表明,在超声换能器频率为1 MHz、采样频率为4 MHz的情况下,时延估计的平均绝对误差在百皮秒内.表明该算法能在较低的采样频率下实现高精度的时延估计,在时延估计精度上比传统相关法更具有优越性.     

电力变压器绕组变形频率响应分析法干扰排查

介绍了变压器绕组变形频响法的干扰因素,提出了防范措施,并结合一起变压器绕组变形频响法试验中的干扰排查案例,分析了干扰排查的过程,为现场变压器绕组变形频响法试验干扰排查提供了借鉴.     

EFFECTS OF NUCLEATION AGENTS ON EFFICIENCY OF BORON EXTRACTION FROM MgO－B_2O_3－SiO_2 SLAGS

ＥＦＦＥＣＴＳＯＦＮＵＣＬＥＡＴＩＯＮＡＧＥＮＴＳＯＮＥＦＦＩＣＩＥＮＣＹＯＦＢＯＲＯＮＥＸＴＲＡＣＴＩＯＮＦＲＯＭＭｇＯ－Ｂ_２Ｏ_３－ＳｉＯ_２ＳＬＡＧＳ￥Ｚｈａｎｇ，Ｐｅｉｘｉｎ；Ｌｏｕ，Ｈａｉｌｉｎｇ；Ｓｕｉ，Ｚｈｉｔｏｎｇ（Ｄｅｐａｒｔｍｅｎ?..     

Oxidation behavior of TiAl coated with a fine-grain Co-30Cr-4Al film

The oxidation behavior of TiAl coupons coated with a fine-grain Co-30Cr-4Al (mass %) film of about 30-m thickness has been studied at 1100–1400 K in a flow of purified oxygen at atmospheric pressure for up to 500 ks. Three oxidation stages were recognized: initial transient, parabolic, and accelerated stages. However, at 1100 K a parabolic stage continues for more than 800 ks. The activation energy for parabolic oxidation agrees with reported values for the oxidation of alumina-former alloys, although the mass gains during the parabolic stages are relatively small at 1200 and 1300 K. Micropores developed mainly at the scale/coating and coating/substrate interfaces as oxidation proceeded. This is attributable to recrystallization of the coating during oxidation and a Kirkendall effect due to preferential diffusion of Co into the substrate. The accelerated oxidation can be explained in terms of the formation of rutile mounds on the scale.     

Mn对Fe_3Al合金室温力学性能的影响

Ｍｎ对Ｆｅ_３Ａｌ合金室温力学性能的影响楼白杨，刘茂森，毛志远，涂江平，肖延龄，钟映宏（浙江大学）Ｆｅ３Ａｌ金属间化合物具有抗氧化耐腐蚀性良、比强度高和成本低等特点［１，２］，从而具有可观的工程应用前景。对这种材料目前国内研究的热点之一是改善其室温塑?..     

Suppression of carbon monoxide formation in oxide-coated TZM molybdenum X-ray rotating anodes

Higher performance designs for rotating anode X-ray tubes have increased the average rotating anode temperature from below 1100 °C to well above 1300 °C. This temperature increase has accelerated the formation of carbon monoxide by reaction of carbon from the alloy substrate with oxygen from the emissive coating. The dominant carbon source is thought to be Mo₂C grain boundary precipitates in the TZM molybdenum alloy substrate. The dominant oxygen source is thought to be TiO in the emissive coating. Placement of a monocarbide-forming reactive layer between the alloy substrate and the emissive coating has been demonstrated to lower the thermodynamic activity of the carbon source and dramatically reduce the rate of formation of carbon monoxide.     

铸造多晶硅中氧的热处理行为研究

研究了铸造多晶硅中不同温度单步退火下氧沉淀的形成规律。实验发现，单步热处理工艺下铸造多晶硅中氧沉淀的形成规律和单晶硅的基本相似，但是在铸造多晶硅中形成氧沉淀的量明显高于直拉单晶硅中氧沉淀的量；在含高密度位错的单晶硅中形成氧沉淀的量远高于无位错单晶硅中氧沉淀的生成量，而有晶界的多晶硅中形成氧沉淀生成量仅稍微高于无晶界单晶硅中氧沉淀生成量。以上结果表明，铸造多晶硅中位错对氧沉淀的形成有明显的促进作用，而晶界则对氧沉淀的促进作用不是很显著。最后，基于实验结果讨论了铸造多晶硅中初始氧浓度，位错和晶界对氧沉淀影响的机理。     

塑料方形把手注射成型工艺的探讨

通过对方形把手的工艺分析,介绍了模具的结构特点及设计方法,满足了产品技术要求,提高了塑件表面质量.     

钢铬钛共渗工艺的研究

对工业纯铁、45钢和3Cr2W8V钢的低真空铬钛共渗进行了研究,探讨了共渗层的组织结构、生长过程以及温度、时间等工艺因素的影响。     

Secure three-party computational protocols for triangle area

In this work, we have put forth two different protocols to address a concrete secure multi-party computational (MPC) problem related to a triangle, of which the coordinates of the three vertices are confidentially kept by the three participants, respectively. The three parties wish to collaboratively compute the area of this triangle while preserving their own coordinate privacy. As one of the merits, our protocols employ weaker assumptions of the existence of pseudorandom generators. In particular, unlike massive secure MPC protocols that rely a lot on oblivious transfer, ours utilize a new computing idea called “pseudorandom-then-rounding” method to avoid this burdensome obstacle. The two protocols are based on different theorems, while they both make use of the same underlying idea. At last, we provide a detailed proof for the first protocol by a series of security reductions of our newly defined games, which seems somewhat stronger than the previous simulation-based proofs and a proof sketch for the second one. Analysis and discussion about the reasons are provided as well to round off our work.