Thermomechanical fatigue—damage mechanisms and mechanism-based life prediction methods

An existing extensive database on the isothermal and thermomechanical fatigue behaviour of high-temperature titanium alloy EVII 834 and dispersoid-strengthened aluminum alloy X8019 in SiC particle-reinforced as well as unreinv conditions was used to evaluate both the adaptability of fracture mechanics approaches to TMF and the resulting predictive capabilities of determining material life by crack propagation consideration. Selection of the correct microstructural concepts was emphasised and these concepts were, then adjusted by using data from independent experiments in order to avoid any sort of fitting. It is shown that the cyclic /-integral (δJ_eff concept) is suitable to predict the cyclic lifetime for conditions where the total crack propagation rate is approximately identical to pure fatigue crack growth velocity. In the case that crack propagation is strongly affected by creep, the creep-fatigue damage parameter δ_CF introduced by Riedel can be successfully applied. If environmental effects are very pronounced, the accelerating influence of corrosion on fatigue crack propagation can no longer implicitly be taken into account in the fatigue crack growth law. Instead, a linear combination of the crack growth rate contributions from plain fatigue (determined in vacuum) and from environmental attack is assumed and found to yield a satisfactory prediction, if the relevant corrosion process is taken into account.     

宣汉——达县地区飞仙关组储层预测方法研究

在宣汉-达县地区,以往仅依据地震属性来预测飞仙关组储层分布,钻探结果与实际情况不符,为此本文提出量化分析预测结合主参数分析的新方法和新思路。在量化分析中首先对飞仙关组储层进行高分辨率反演,获得储能系数图;然后结合主振幅剖面和主频率剖面分析,对储层进行预测。在研究区,本方法的预测结果与实钻情况相吻合。     

盐家油田油水井结垢原因探讨

对地层温度65～75℃的盐家油田油水井近井地带、井底、井筒发生严重结垢的原因进行了分析探讨。7口油井采出的地层水均为NaCO3型水．矿化度6．4～10g／L，HCO3浓度高（1．6～3．7g／L），Ca^2＋＋Mg^2＋浓度较低；1口水源井水及1口水井注入水为CaCl2型水，矿化度32～33g／L，Ca^2＋＋Mg^2＋浓度高（3．1～3．8g／L）而HCO3浓度低；采用CaCO3饱和指数法和CaSO4热力学溶解度法预测，在70℃下所有水样均有CaCO3结垢趋势，除3口油井采出的地层水外，均有CaSO4结垢趋势。3口油井采出的地层水与水源水在25℃按不同比例混合后，悬浮物含量大幅度上升。在70℃放置7天后再次大幅度上升，烘干的悬浮物易溶于稀盐酸．其主要成分为碳酸盐．说明注入水、地层水不配伍。1口电泵采油井和1口注水井油管垢样含盐酸可溶物（碳酸盐）超过90％。讨论了碳酸盐、硫酸盐垢的生成条件：温度、压力及pH值。图1表4参3。     

"Temporal encoding in fear conditioning revealed through associative reflex facilitation": Correction to Lindquist and Brown (2004).

Reports an error in "Temporal Encoding in Fear Conditioning Revealed Through Associative Reflex Facilitation" by Derick H. Lindquist and Thomas H. Brown (Behavioral Neuroscience, 2004[Apr], Vol 118[2], 395-402). The article contained several errors. On page 396, second paragraph, the sentence beginning on line 6 should read as follows: "Having a stable baseline is critical for studies of reflex facilitation because the experimental designs invariably entail repetitive CR testing, if only to achieve reasonable statistical power (see Choi et al., 2001b; Lindquist & Brown, 2004)." On page 400, the first heading should read as follows: "Comparison of New and Old Reflex Facilitation Procedures." On page 400, the first sentence under the abovementioned heading should read as follows: "We decided not to use the original measure of reflex facilitation, developed by J. S. Brown et al. (1951), because it suffers from severe interpretational limitations, elaborated in detail elsewhere (Choi et al., 2001b; Leaton & Cranney, 1990; Lindquist & Brown, 2004)." (The following abstract of the original article appeared in record 2004-12681-016.) Temporal encoding in Pavlovian fear conditioning was examined through conditional facilitation of the short-latency (Rl) component of the rat eyeblink reflex. Rats were fear-conditioned to a tone conditional stimulus (CS) with either a 3- or 9-s interstimulus interval (ISI) between CS onset and the onset of the grid-shock unconditional stimulus (US). Rl facilitation was tested over 2 days, in counterbalanced order, at a latency of 3 s and 9 s from CS onset. CS-produced Rl facilitation, the conditional response (CR), was 3-4 times larger when the test latency equaled the conditioning ISI. These results, coupled with the known neurophysiology of Rl facilitation, suggest that this CR could disclose differences in the time course of CS-generated output from the amygdala when driven by cortical versus subcortical CS-CR pathways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Novel Channel Predictor Based on Constrained Hidden Markov Model

1　Introduction　Linkadaptationtechniqueisnowwidelyrecognizedasakeysolutiontoincreasethespectralefficiencyofwire lesssystems[1～ 3] .GPRS ,EDGE ,cdma2 0 0 0andWCDMAallincludelinkadaptationasameanstopro videhigherdatarates[4～ 5] .Torealizethepotentialoflinkadaptation ,reliablechannel predictionisneces sary[6 ] .　Therearemanydifferentchannelpredictionmethodsavailablenow ,suchasLongRangePrediction(LRP) [6 ] ,predictionbasedonsubspacesignalprocess ingalgorithms[7] ,predictionbasedonFinit…     

灰色预测法在西安市农村电话预测中的应用

在对西安市农村电话发展现状分析的基础上 ,运用灰色预测法对西安市农村电话未来发展趋势进行预测 ,为制定西安市农村电话发展策略提供参考     

A time series approach to fatigue crack propagation

The inherently nonlinear phenomenon of fatigue crack propagation is modeled as a linear random process. To a first approximation, simple, nonstationary time series models are introduced and standard techniques for determining the parameters of autoregressive integrated moving-average processes are applied. Multiplicative time series models are next utilised for the representation of a group of crack history curves. Implementation of the models on the Virkler experimental data set yields satisfactory results. Reliable Gaussian approximations to the distribution of the time required by a crack to reach a specified critical length are obtained, and the usefulness of the approach is demonstrated when updating lifetime predictions after periodic inspections.     

利用单片机80c196kc实现等间隔采样及采样值的回显

本文主要介绍以单片机80c196kc为CPU对模拟信号进行等间隔采样以及实现对采样值回显的问题。详细介绍了测频软件及电路的实现，对等间隔采样软件实现进行了详细论述：详尽讨论了对于MG-12864-2液晶显示器的电路连接与软件控制方法；对MG-12864-2液晶显示器应用的独特之处做了细致的分析。     

一种高并行度的H.264帧内预测器的VLSI设计

分析了帧内预测的17种模式,对于每个4×4大小块的16个像素点的不同模式的预测公式之间的相同运算,采用数字强度缩减的方法去除计算的冗余,提出了一种高并行度的帧内预测器,可以每个时钟周期处理16个像素点的预测值。基于SMIC0.18μm工艺,用verilog对该设计进行了VLSI实现,综合后的电路的关键路径最大时延为10ns,电路规模不超过1.4万门,数据吞吐率可以达到1600Msamples/s。从实现结果来看,与采用可重构方法的设计相比,该设计在相同的并行度下减小了电路面积,简化了控制逻辑。     

Oxygen transport rate on Rhodococcus erythropolis cultures: Effect on growth and BDS capability

The influence of oxygen transport rate on Rhodococcus erythropolis cultures has been studied in a stirred tank bioreactor under different transport and uptake conditions. Oxygen uptake rate has been measured by applying a modified dynamic method and a kinetic model is proposed, obtaining the kinetic parameter values: specific maintenance and yield coefficients. The volumetric mass transfer coefficients under inert conditions, k_La, and during the bioprocess, K_La, have been determined. The values obtained are different and a biological enhancement factor E, has been considered. These parameters have been predicted by the theoretical model and good agreement with experimental data under the conditions studied has been found. The oxygen limitation has been expressed by a modified dimensionless Damköhler number, Da, the relationship between transport and biological reaction rates. This number decreases with increasing stirrer speed; that is, when mass transport resistance decreases. The efficiency of oxygen utilization can be determined by a film effectiveness factor, η. The effectiveness factor was found to be a strong function of Damköhler number and decrease with increasing Da. Furthermore, oxygen concentration into culture depends on the mass transfer and consumption rates. The theoretical model proposed is able to reasonably predict the evolution of dissolved oxygen concentration with time of cultivation.