Deriving real-time action systems in a sampling logic

Action systems have been shown to be applicable for modelling and constructing systems in both discrete and hybrid domains. We present a novel semantics for action systems using a sampling logic that facilitates reasoning about the truly concurrent behaviour between an action system and its environment. By reasoning over the apparent states, the sampling logic allows one to determine whether a state predicate is definitely or possibly true over an interval. We present a semantics for action systems that allows the time taken to sample inputs and evaluate expressions (and hence guards) into account. We develop a temporal logic based on the sampling logic that facilitates formalisation of safety, progress, timing and transient properties. Then, we incorporate this logic to the method of enforced properties, which facilitates stepwise refinement of action systems.     

中国海洋石油天然气(湿气)能量贸易交接计量研究及应用

湿气高精度贸易计量是国际性难题,因为湿气气相部分含有重烃、游离水,与经过处理后的外输气(干气)组分相差较大;湿气液相部分含烃(溶解气)常规仪表无法达到贸易计量精度,而带压化验(4万元/次)费用过高,降低效益。中海油南海某气田(中海油自营)水下井口物流经20km海管回接至原有YC13-1平台(中外合资)后为了降底投资,提高效益必须面对湿气贸易计量问题,此外还要解决来自海管段塞流对计量精度的冲击。本文将介绍湿气能量贸易计量解决方案,在中海油南海某气田开发项目中的应用、技术先进性及效益。     

KNOWLEDGE-BASED ASSESSMENT OF STREAM SAMPLING

This article presents two novel knowledge-based systems for stream-sampling assessment. The first expert system inspects the stream-sampling correctness in mineral-processing plants. It is called the sampling correctness inspector. The second expert system evaluates sampling errors in mineral-processing plants. It is called the sampling error evaluator. The knowledge of both expert systems is collected from the authors' expertise, in addition to other experts' knowledge of sampling mineral-processing streams. These knowledge-based systems take into account the stream properties, the cutter features, and the sampling manner. They were developed and tested successfully.     

Resonant frequency characterization of MEMS based energy harvesters by harmonic sampling analysis method

This paper presents a new and accurate experimental method based on harmonic distortion analysis to determine the resonant frequency of MEMS devices to be used as energy scavengers or more generally in widespread MEMS-based applications. This technique uses the mechanical–electrical analogy of MEMS variable capacitor acting as a low-pass filter to give access to both resonant frequency and damping factor of the mechanical system through the determination of the filter parameters as the cut-off frequency. Resonant frequencies ranging from 0.8 kHz to 5 kHz of electrostatic actuated MEMS-based harvesters have been measured by this technique with an uncertainty as low as a few parts in 10³ in a good agreement with measurements carried out by using Deep Level Transient Spectroscopy system.     

Selection of sampling points for accurate evaluation of flatness error using coordinate measuring machine

Dimensional inspection, in integrated manufacturing environments, requires accurate inspection while minimizing the cost and time of inspection. The selection of sampling plan—sample size and sample point locations, the method of evaluating the form error and the nature of the manufactured surfaces will play an important role in deciding the best inspection strategy to be adopted. This paper deals with the strategy for evaluation of flatness error which is one of the most commonly used form tolerances for control of manufactured surfaces. Investigations have been carried out to ascertain the influence of surface quality (surface roughness) in determining the sampling strategy for accurate determination of flatness error while inspecting on a coordinate measuring machine (CMM). The sampling plan utilizes the Hammersley sequence for point location and the flatness error is evaluated using the minimum zone method (MZM) based on computational geometry techniques. Results indicate that the surface roughness influences the accuracy of inspection and can be used as a parameter for determining an initial sample size for the determination of flatness error.     

Total Volatile Organic Compounds (TVOC) in Indoor Air Quality Investigations*

Abstract The amount of volatile organic compounds (VOCs) in indoor air, usually called TVOC (total volatile organic compounds), has been measured using different definitions and techniques which yield different results. This report recommends a definition of TVOC referring to a specified range of VOCs and it proposes a method for the measurement of this TVOC entity. Within the specified range, the measured concentrations of identified VOCs (including 64 target compounds) are summed up, concentrations of non-identified compounds in toluene equivalents are added and, together with the identified VOCs, they give the TVOC value. The report reviews the TVOC concept with respect to its usefulness for exposure assessment and control and for the prediction of health or comfort effects. Although the report concludes that at present it is not possible to use TVOC as an effect predictor, it affirms the usefulness of TVOC for characterizing indoor pollution and for improving source control as required from the points of view of health, comfort, energy efficiency and sustainability.     

Sample size and error in the determination of mode shapes by principal components analysis

Principal components analysis (PCA) is a multivariate statistical technique that transforms a data set having a large number of inter-related variables to a new set of uncorrelated variables called the principal components, determined to allow the dimensionality of the data set to be reduced while retaining as much of the variation present as possible. PCA can be applied to dynamic structural response data to identify the predominant modes of vibration of the structure. Because PCA is a statistical technique, there are errors in the computed modes due to the use of a sample of finite size. The aim of this paper is to study the effect of sample size on the accuracy with which the modes of vibration can be computed. The paper focuses predominantly on elastic response data and examines the potential influence of various parameters such as the period of the structure, the input excitation, and the spatial distribution of mass over the structure. Issues relating to errors in the modes of nonlinear structures are also discussed.     

取样位置对质量控制参数的影响评价

热拌沥青混合料（HMA）的取样质量对试验结果有着显著的影响。研究利用工地生产的混合料对运料车、摊铺机后及路面钻芯三种不同的取样方式进行了比较研究。结果表明，虽然三种取样方式获取的混合料试验的实验室特性在数学理论统计意义上没有显著的差别（沥青用量除外），但运料车上取样时很容易发生离析现象，导致获取的级配偏细、沥青用量偏高及空隙率偏低。     

包气带核素迁移示踪试验的土芯取样技术

研究了一套简便实用的包气带土芯采样装置，针对实际采样过程中出现的问题，对采采装置进行了改进，取得了较好的效果。     

Time of Sampling Strategies for Asphalt Pavement Quality Assurance

The cost of quality assurance programs in asphalt road construction is high in part because of the need for daily testing. This paper demonstrates the methodology used to investigate the timing of sampling and its effect on the quality assurance program. Fourteen lots over two highway paving projects were tested twice: during construction on a daily basis, and after construction was complete. Three quality measures were compared, namely asphalt content, degree of compaction, and aggregate gradation. The test data during construction were obtained from two sources: the consultant’s quality assurance, and the contractor’s quality control. One-way ANOVA tests and T-tests were used to compare the means. In addition, the arithmetic difference between the means was reviewed to understand how the time of sampling might affect contractor payment adjustments.