技术哲学视阈中的风险和安全

对风险和安全哲学进行了概述,对与之相关的风险、不确定性、安全性和预防等核心概念进行了界定,特别强调了风险和不确定性的区分,并且论述了这种区分的重要性.以对科学中不确定性信息的处理的讨论为基础,论述了在科学的不确定性情形下进行决策的问题,澄清了预防原则的作用.探讨了如何实施安全工程的主要方法,强调了诸如内在安全性、安全因素和多重安全阻抗等安全原则的作用.在此基础上,指出风险性和安全性问题是技术哲学研究中的重要领域.     

四川移动数据网络总体建设思路探讨

通过对省CMNET骨干网、IP城域数据网、IP宽带数据接入网3个主要网络层次的工程建设定位、技术特点、建设原则进行的分析,总结出在目前市场竞争条件下进行移动数据网络建设的相关思路。     

Resonant degenerate four-wave mixing in I(2): effect of buffer gas pressure

The influence of molecular collisions on the production of the degenerate four-wave mixing signal in I(2) is presented. Measurements were performed on gaseous molecular iodine, I(2), contained in a glass cell in which pressure, temperature, and species concentration are easily and independently varied. Frequencydoubled outputs from a seeded Nd:YAG laser and an excimer-pumped dye laser were used as excitation sources. We have studied the dependence of signal strength versus buffer gas pressure, with pump intensity as a third parameter. It is evident from our results that, for pump intensities of less than 1 MW/cm(2), the pressure dependence of the signal follows that given by a simple two-level model in the homogeneously broadened regime. In this regime collisional deexcitation becomes significant, leading to changes in saturation intensity. This is evidenced by a reduction in the signal with an increase in buffer gas pressure. This behavior is similar to that seen in laser-induced fluorescence. At higher pump intensities, the signal is seen to increase with pressure; this behavior cannot be described by the simple two-level model.     

The XT-tube extractor: a hollow fiber-based supported liquid membrane extractor for bioanalytical sample preparation

A new supported liquid membrane extractor for bioanalytical sample preparation is presented. The extractor consists of a polypropylene hollow fiber mounted inside a PTFE tube by means of a cross-connector and a tee-connector. All parts are commercially available, inexpensive, and easily assembled. An organic solvent in the pores of the fiber forms a liquid membrane that separates the sample, which is pumped along the outside of the fiber, from the acceptor phase, which is pumped inside. The length of the hollow fiber may easily be varied to meet different demands on extractive surface and extract volumes. To test the system, the strongly acidic plasticizer/flame retardant metabolite diphenyl phosphate ester (DPhP), with a pKa value of 0.26, was extracted from urine. DPhP was protonated using 4 M hydrochloric acid and extracted into an acceptor phase at pH 9. Thirty extractions were made with the same liquid membrane without any decrease in extraction efficiency and with a relative standard deviation <7%. An analyte concentration enrichment of 5-10 times was achieved in the extraction step, giving a limit of detection (S/N = 3) of 0.014 microg/mL with LC/ESI-MS and 0.18 microg/mL with CE-UV. The effects on extraction efficiency using different sample pH, organic solvents, sample flow rates, and lengths of the fiber were evaluated.     

Simulation of sea surface wave influence on small target detection with airborne laser depth sounding

A theoretical model for simulation of airborne depth-sounding lidar is presented with the purpose of analyzing the influence from water surface waves on the ability to detect 1-m3 targets placed on the sea bottom. Although water clarity is the main limitation, sea surface waves can significantly affect the detectability. The detection probability for a target at a 9-m depth can be above 90% at 1-m/s wind and below 80% at 6-m/s wind for the same water clarity. The simulation model contains both numerical and analytical components. Simulated data are compared with measured data and give realistic results for bottom depths between 3 and 10 m.     

Reliability of an engineering system under a strong earthquake with application to offshore platforms

This paper presents a method developed for the performance evaluation of an engineering system during a strong earthquake. The seismic reliability of the system is evaluated by considering the different possible failure modes, and seismic reliability of the components of the system. The method is applied to the oil production system at the Statfjord Field in the North Sea. The objective of the analysis is to document the reliability of oil production from the field in the event of an exceptionally large earthquake, and to investigate the effect of spatial variation of earthquake loading parameters on the computed system reliability. It is shown that, with a realistic model of the spatial variation of earthquake motion, there is very little correlation between the earthquake loading parameters at different platform locations. The main consequence of this lack of correlation is that the computed failure probability of the oil production system under the design earthquake is about one order of magnitude smaller than the probability of failure of individual platforms at the Statfjord Field.