我的家

我生于东京的银座,那是个靠近传统花街柳巷、歌舞升平的地方,在童年的记忆里那里随时随地都是一片华美景象。而在这些景象的背后有一排排美丽的临街二层长屋建筑,大都是料亭,还有颇有风致的砖结构剧场。那时父母在这里经营着咖啡馆,街上的行人总是把店里挤得满满的。数年前父亲     

石家庄市室内氡及其子体浓度

本文报道了用双滤膜法对石家庄市室内空气中氡及其子体浓度的调查结果。47个房间室内氡年平均浓度为17.0Bq·m~(-3),氡子体平均浓度是7.14Bq·m~(-3)。氡及其子体浓度的日变化是清晨4—8时出现峰值。季节变化是夏秋季低,冬季高,全年的最低值出现在8月,最高值出现在11月。     

A wavelet-based procedure for process fault detection

To detect faults in a time-dependent process, we apply a discrete wavelet transform (DWT) to several independently replicated data sets generated by that process. The DWT can capture irregular data patterns such as sharp "jumps" better than the Fourier transform and standard statistical procedures without adding much computational complexity. Our wavelet coefficient selection method effectively balances model parsimony against data reconstruction error. The few selected wavelet coefficients serve as the "reduced-size" data set to facilitate an efficient decision-making method in situations with potentially large-volume data sets. We develop a general procedure to detect process faults based on differences between the reduced-size data sets obtained from the nominal (in-control) process and from a new instance of the target process that must be tested for an out-of-control condition. The distribution of the test statistic is constructed first using normal distribution theory and then with a new resampling procedure called "reversed jackknifing" that does not require any restrictive distributional assumptions. A Monte Carlo study demonstrates the effectiveness of these procedures. Our methods successfully detect process faults for quadrupole mass spectrometry samples collected from a rapid thermal chemical vapor deposition process     

标准椅全身计数器对不同年龄组均匀体模源全能峰效率的刻度

本文介绍了用标准液体源均匀充入聚氯乙烯制的体模,刻度标准椅全身计数器〔φ8″×4″(NaI)〕的方法和结果。分别就代表6个年龄组的体模,测定了标准椅全身计数器对5种能量(364,637,898,1460和1836keV)γ射线的全能峰效率;给出了全能峰效率与γ射线能量和被测对象体重的关系曲线。     

秦山核电厂气载放射性释放的环境影响

本文评价了秦山核电厂气载放射性流出物对环境的影响。应用现场及风洞大气扩释实验结果和厂址周围的人口与食谱调查资料,估算了秦山核电厂在正常运行和事故条件下释放的气载放射性流出物对公众产生的个人有效剂量当量和集体有效剂量当量。计算结果表明,正常运行时厂址边界(0.5km)处的最大个人有效剂量当量为2.7×10~(-2)mSv/a,该剂量的大部分来自~(137)Cs 的食入(主要由地表湿沉积引起);80km 范围内的集体有效剂量当量为1.1人·Sv/a,归一化集体有效剂量当量为3.7人·Sv/GW(e)·a。文中还给出了事故情况下剂量估算结果。     

Application of asymptotic waveform evaluation to eigenmode expansion method for analysis of simultaneous switching noise in printed circuit boards (PCBs)

In this paper, the asymptotic waveform evaluation (AWE) technique is first applied to the conventional eigenmode expansion method for characterizing a power/ground (P/G) plane pair and analyzing the simultaneous switching noise on such plane pairs for printed circuit boards or multichip modules. The application of AWE avoids a large number of iterations in computing the impedance frequency response of a P/G plane pair structure and greatly reduces the computation time. Meanwhile, to obtain an accurate solution in an entire frequency range, we employ the complex frequency hopping technique which can help select multiple expansion points. In addition, the proposed approach can also be used to characterize the P/G plane pair structures with irregular shapes. Three examples demonstrate its high efficiency and good accuracy.