The effect of secondary task load on visual sampling behaviour

This paper investigates a dual-task experiment, which looked at whether periodical sampling (Senders 1983) of relatively fast changing instruments results from an imperfect internal representation of these instruments, or whether it merely represents a strategy adopted by the observer to overcome overload situations. Subjects either monitored a fast or a slow instrument in combination with a difficult, easy or no tracking task. The results indicated that sampling behaviour was generally unaffected by the external load imposed by the tracking task, suggesting that periodical sampling results from an imperfect internal representation and is not the result of a strategic decision of the observer to overcome overload.     

多气源混输管道在线气相色谱仪安装位置的确定方法

采用在线气相色谱仪实时监测管道中天然气组分的变化是目前大型输气场站保证天然气计量准确性的关键工艺,而在线气相色谱仪抽取样品的代表性则是保证分析检测结果准确可靠的关键因素,对于多气源汇合的输气场站,不同气源天然气的混合程度直接关系到在线气相色谱仪所取样品的代表性。为此,以中石化川气东送工程的普光首站为例,按照该站的工况条件,采用FLUENT软件对多气源天然气的混合规律进行了仿真模拟,探讨了多气源天然气混合距离与温度、压力、流速等因素的关系,以及多气源天然气混合均匀的最近位置。试验结果表明:(1)含两种不同摩尔分数值组分的天然气在汇管不同位置处混合的均匀程度不同——距汇管50 m处天然气各组分混合不均匀,具明显分层现象,距汇管150 m处天然气各组分的混合开始呈现均匀状态,但仍存在分层现象,距汇管280 m处天然气各组分混合完全呈现出均匀状态,其CH_4摩尔分数为98.30%,CO_2摩尔分数为0.95%;(2)在普光首站距混合点280 m以远处的位置安装在线气相色谱仪取样较为合适;(3)对于气源体积流量或气源的体积流量差别较大、压力较高或温度较低的工况条件,在线气相色谱仪的取样点可适当靠近混合点。     

密闭环保取样系统的应用与改进

密闭环保取样器适用于石油、化工装置中对管道内工艺状况下的各种介质,尤其是有毒、有害、易燃、易爆等危害性的高中低压气液介质的无泄漏采样.取样器由箱体、采样瓶、快插、压力表、阀门、密封件及法兰组成.样品真实性强、准确性高、无残液、残气排放,有效地防止有毒、有害介质对操作者的伤害,同时不会污染环境,避免了易燃、易爆介质在采样...     

导弹伺服机构中电液伺服系统故障诊断方法研究

为实现导弹伺服机构中电液伺服系统这类复杂系统的故障诊断,依据系统特点通过故障分析建立故障库,从系统中抽取局部采样点,再与故障库对比来进行故障诊断.通过实例验证了这一方法的实用性和有效性,为类似复杂液压系统故障诊断的实现提供了参考.     

一种应用于PD的高精度限流保护调节电路

在POE(PowerOverEthernet)系统的终端受电设备中,限流保护调节电路保证了其稳定可靠工作。根据IEEE802.3af标准规定,受电设备开关电源启动到正常工作的过程中,电流要限制在100mA以内,在正常工作情况下电流要限制在390mA以下。本设计通过栅源比例电阻使采样功率管栅源电压与输出功率管的栅源电压保持一致,采样功率管精确采样输出功率管的电流值,采样电流经栅源比例电阻转换为电压后,调节输出功率管栅源电压,来完成PD(PowerDevice)限流保护。     

Preliminary and Scoping Analysis for Uncertainty of HLW Geologic Repository Performance with Multiple Canister Repository Model by Earth Simulator

An uncertainty analysis of repository performance has been made by the VR code, which incorporates interference effects of multiple canisters in a repository. A problem of the previous study with the VR code is that the number of connected canisters was determined arbitrarily. In this study, first, the probability distribution functions for the number of canisters connected by the flow-bearing fracture clusters have been determined by the FFDF code, and then uncertainty associated with the peak fractional release rate of ²³⁷Np to the far field resulting from uncertainties with the buffer sorption coefficient, solubility, and the number of connected canisters has been numerically evaluated by the Latin-Hypercube Sampling method. The effects of uncertainty with the total number of connected canisters become less important as the number increases because the radionuclide concentration saturates in downstream compartments. Uncertainty with the buffer sorption and solubility shows an important contribution to that with the nuclide release rate.     

Efficient Sampling by Artificial Attributes

Hypotheses about the fraction of items in a lot possessing a “specification attribute” X < L can be tested by generally sampling the variable X or directly sampling the attribute of interest. When the process variance is known, it is often more efficient to test against “compressed limits” for one or more “artificial” attributes X < L_a , X < L_b etc.

This study discusses the efficient choice of one or two compressed limits. General guidelines for this choice are suggested, and then evaluated under many hypothetical test specifications. One compressed limit offered ~40% – 97% savings over direct attribute sampling; two limits allowed about 20% further savings.     

A Dual Purpose Cost Based Quality Control System

This paper considers the development of a cost based industrial quality control system which functions both as an acceptance sampling plan and as a means for determining an assignable cause of quality variation in the manufacturing process. The manufacturing faci1ity studied normally produces items at a relatively constant proportion defective. The facility is subject, however, to random failures in time which cause the proportion defective to shift upwards. The objective of the paper is to develop a sampling plan which minimizes the expected total annual cost of quality control by determining t)he sample size, acceptance number, and time period between successive samples. The optimization technique employed is a combination of a multivariate search technique and a partial enumeration.     

单元特性提取中采样点偏离现象的研究

为使应用于集成电路设计中的单元时序信息库更能反映实际情况，研究了特性提取中出现的采样点分布偏移和格点偏离现象，并提出了有效的解决方法。该方法通过建立查表模型，无需多次重复仿真就能准确定位任意采样点。理论分析和仿真结果均表明，该方法不仅耗费时间少；定位也能满足单元建库的要求，经过实例化后，能很好地应用于超深亚微米工艺下的单元特性提取。     

一种新型高线性度MOS采样开关

提出了一种提高MOS采样开关线性度的新方法。通过采用电阻分压电路实现一个处于线性工作状态的“复制”MOS管,使其与采样MOS管具有相同的阈值电压。较之传统栅压自举开关,此新型MOS采样开关能够消除由于阈值电压随输入信号变化所产生的非线性。基于Char-tered 0.35μm标准CMOS工艺设计的新型采样开关,在输入信号为30 MHz正弦波,峰-峰值为1V,采样时钟频率为80 MHz时,无杂散动态范围达到了110 dB,较之自举采样开关提高了12 dB左右;同时,导通电阻的变化减小了90%。