改进型雷达液位计在槽体液位测量中的应用

雷达液位计在测量液位过程中有着众多优点,但对于易挥发结晶介质的液位测量却存在不同程度的局限性。为增强雷达液位计的使用性能,通过对生产过程中使用的雷达液位计在对槽体液位测量中出现的一系列问题进行深入分析,并结合雷达液位计的测量原理和结构特点,提出了一种利用雷达液位计与导波管相结合的测量方法,为化工企业生产中雷达液位计的使用提供了参考。该改进型雷达液位计结构简单,易于安装与维护,有效避免了槽体液位测量中液位波动、测量介质等因素的影响,使测量精度提高了10倍以上,抗干扰能力大大增强,确保了测量结果的稳定性和准确性。该改进型雷达液位计的创新性在于结合了导波管与雷达液位计的优点,成功解决了雷达液位计在液位测量过程中的局限性。该研究成果解决了槽体液位测量过程中常见的问题,同时为石化、焦化、化工等行业生产过程中雷达液位计的使用方法提供了一些启示。     

论氨球罐液位计选型

生产出的液氨一般存储在球罐里,而液氨具有可急剧挥发的特性,存在液位测量比较困难的问题。分别介绍了几种液位计,如雷达液位计、差压液位计、磁翻板液位计、伺服液位计在使用过程中存在问题,选出比较合理的测量液位计。     

改进型浮子液位计在槽体液位测量中的应用

浮子液位计在液位测量中应用非常广泛。但是,对于易于挥发结晶的介质和黏稠状介质,传统浮子液位计的使用会受到影响。由于地下槽体测量环境复杂、干扰因素较多,基于地下槽体液位测量环境的实际状况,并结合传统浮子液位计的测量原理和结构特点,提出了一种具有高精确度、制作方便、环境适应程度高、抗干扰性强、耐腐蚀能力强、维护使用方便等诸多优势的改进型浮子液位计。该改进型浮子液位计不仅继承了传统浮子液位计优点,并通过结构改造,成功克服了传统浮子液位计在液位测量过程中的局限性。该研究成果解决了地下槽体液位测量过程中常见的问题,同时为石油,焦化,化工等行业生产过程中地下槽体液位计的使用提供了参考。     

SmartRadar液位计在罐区的应用

测量精度是储量管理系统的主要指标,雷达是储罐液位测量的最新应用技术之一。Enraf公司的SmartRadar雷达液位计是一个采用了数字平面技术的智能雷达液位计,它大大提高了测量精度。对其测量原理和结构特点进行了介绍,并描述了储罐计量控制系统的组成,进而分析说明了雷达液位计在罐区测量中的优势。     

浮筒液位计校验仪的设计开发

浮筒液位计作为一种液位测量仪表,在油气的生产过程中得到了极其广泛的应用。浮筒液位计主要应用于敞口或者压力容器的液位测量和界面测量。本文通过对于油气生产中广泛使用的浮筒液位计的相关原理和开发目的进行的详细的分析。     

常见浮选液位测量装置的分析及对比

为了解决浮选控制过程中的液位计选型问题,从现场应用出发,分析对比了常用的浮力式液位计、激光液位计、静压液位计、超声波液位计等浮选液位测量装置的基本结构、工作原理及现场应用情况。分析认为因传感器性能、附属装置稳定性、测量介质等不同,各测量装置均有优缺点,实际应用时应综合考虑现场浮选生产过程具体情况、维修条件、装置性能、安装使用费用等因素,选择合适的浮选液位测量装置。     

外测式液位计在石油化工生产中的应用

外测式液位计采用隔离式测量,适合在特殊场合使用;自校准设计提高测量精度;安装简便,维护量小,使用安全可靠.本文叙述了外测式液位计的工作原理和特点,根据与其他液位计实际使用结果对比,表明外测式液位计在特殊使用条件下,有一定推广使用价值.     

基于多计数管的宽量程液位计

针对传统的基于射线探测器的液位计探测范围小的缺点,文章提出了一种基于多计数管的宽量程液位计的设计方案,介绍了该液位计的测量原理及射线计数和被测液位之间的数学关系,并给出了该液位计中探测器的设计电路及多计数管的标定过程。该液位计由多个计数管串联组成,使探测器有效接收射线的范围扩大,探测范围可达到3 m,达到了其它测量方式难以实现的量程和测量精度。     

FMR230雷达液位计在原油罐上的应用及维护

通过对原油缓冲罐液位测量问题进行研究,提出了原油拱顶罐液位测量的方法和现状,以及新的雷达波测距技术.介绍了采用雷达液位计作为液位测量仪表以及非接触式测量方式,解决原油缓冲罐的液位测量问题.说明了FMR230雷达液位计的工作原理及特点.重点介绍了该型雷达液位计在原油罐上的安装要求、影响精度的因素,以及FMR230基本参数的设置过程、故障排查的基本方法.     

基于外贴式液位开关的球罐SIS安全仪表系统设计

液位是储罐主要的控制参数,形式不同的储罐液位测量要求也不尽相同,本文根据外贴式液位开关的工作原理分析了其在实际使用中的优势。在化工生产中,为防止和降低石油化工工厂或装置的过程风险需设置SIS安全仪表系统,该系统的合理设计以及运行情况直接影响到装置的安全运行。本文针对某项目中的重大危险源丁二烯球罐,根据其SIL等级分析确定了球罐SIS系统的主要控制参数,具体设计了基于外贴式超声波液位开关的SIS安全仪表系统及完整的联锁控制,并投入生产运行。在实际生产中外贴式超声波液位开关可靠性高、维护简单,工作量小,设计的SIS系统安全稳定性高、运行情况良好,保证了项目罐区和整个厂区的安全生产。     

Nonlinear H∞-control of time-varying systems: aunified distribution-based formalism for continuous and sampled-datameasurement feedback design

Nonlinear H_∞-controller synthesis is presented for time-varying systems via sampled-data measurement feedback. The H _∞-control problem for a nonlinear system with a sampled-data measurement output is shown to be equivalent to the H_∞-control problem for a certain nonlinear system with a time-continuous measurement output. Special mathematical tools are developed to straightforwardly derive a local solution of the sampled-data measurement feedback (SMF) H_∞-control problem from that of the time-continuous measurement feedback (CMF) H _∞-control problem     

顺序更新式无序量测处理算法

在集中式多传感器目标跟踪系统中,常出现源自同一目标的量测到达处理中心时的乱序现象,即无序量测问题。本文借鉴等价量测与重新滤波法的思想,提出一种基于等价量测的顺序更新式无序量测处理算法。该算法用等价量测来代替重新滤波法中需要缓存的量测序列,然后从无序量测处开始用无序量测和等价量测进行顺序更新。通过理论分析和仿真实验证明:该算法在处理一步延迟时是最优的,在处理多步延迟时,接近最优;且该算法有较高的滤波精度和较小的额外存储量。     

Transition matrices in the measurement and control of synchronous sequential machines

This paper develops a matrix approach to the solution of the measurement and control problems in synchronous sequential machines. The control problem in sequential machines is concerned with finding input sequences that take a given machine from a known initial state to a predesignated terminal state. There may be many different measurement problems of interest in sequential machines. One important measurement problem is the identification of the unknown initial state of the machine, called the initial-state identification problem or diagnosing problem; another important measurement problem is the identification of the terminal state of the machine, known as the terminal-state identification problem or homing problem, of which a special case is the synchronizing problem. These measurement problems may be solved by applying predetermined input sequences to the machine and noting the resulting output sequences. The conventional approach to the solution of these measurement and control problems is to make use of the information contained in the transition table of the machine in conjunction with its response tree, which is basically an exhaustive tree search process. In the present paper, instead of using the transition table and the corresponding response tree, we use only the transition matrix representation of the machine and its higher order forms to solve the aforementioned problems. The suggested approach is very systematic and completely algorithmic, and thus lends itself to easy computer implementation.     

带有色厚尾量测噪声的鲁棒高斯近似滤波器和平滑器

为了解决带有色厚尾量测噪声的非线性状态估计问题,本文提出了新的鲁棒高斯近似（Gaussian approximate,GA）滤波器和平滑器.首先,基于状态扩展方法将量测差分后带一步延迟状态和白色厚尾量测噪声的非线性状态估计问题,转化成带厚尾量测噪声的标准非线性状态估计问题.其次,针对量测差分后模型中的噪声尺度矩阵和自由度（Degrees of freedom,DOF）参数未知问题,设计了新的高斯近似滤波器和平滑器,通过建立未知参数和待估计状态的共轭先验分布,并利用变分贝叶斯方法同时估计未知的状态、尺度矩阵、自由度参数.最后,利用目标跟踪仿真验证了本文提出的带有色厚尾量测噪声的鲁棒高斯近似滤波器和平滑器的有效性以及与现有方法相比的优越性.     

Optimal sensor scheduling for hidden Markov model state estimation

Consider the Hidden Markov model where the realization of a single Markov chain is observed by a number of noisy sensors. The sensor scheduling problem for the resulting hidden Markov model is as follows: design an optimal algorithm for selecting at each time instant, one of the many sensors to provide the next measurement. Each measurement has an associated measurement cost. The problem is to select an optimal measurement scheduling policy, so as to minimize a cost function of estimation errors and measurement costs. The problem of determining the optimal measurement policy is solved via stochastic dynamic programming. Numerical results are presented.     

一种估计WLAN竞争站点数的方法

在802.11WLAN中,竞争的站点数在网络性能的优化中是一个重要的参数。针对现有的概率测量法和中断测量法的实时性较高,但测量精度较差的问题,提出基于退避时间的竞争站点数测量法。该方法考虑站点的退避时间长短对测量结果的影响,对中断测量法进行改进,并给出实现算法。仿真实验结果表明,该方法是一种具有较好测量精度的测量方法。     

An application of system identification in metrology

Metrology is advancing by development of new measurement techniques and corresponding hardware. A given measurement technique, however, has fundamental speed and precision limitations. In order to overcome the hardware limitations, we develop signal processing methods based on the prior knowledge that the measurement process dynamics is linear time-invariant.Our approach is to model the measurement process as a step response of a dynamical system, where the input step level is the quantity of interest. The solution proposed is an algorithm that does real-time processing of the sensor's measurements. It is shown that when the measurement process dynamics is known, the input estimation problem is equivalent to state estimation. Otherwise, the input estimation problem can be solved as a system identification problem. The main underlying assumption is that the measured quantity is constant and the measurement process is a low-order linear time-invariant system. The methods are validated and compared on applications of temperature and weight measurement.     

Optimal activation policies for continuous scanning observations in parameter estimation of distributed systems

The problem of determining an optimal measurement scheduling for identification of unknown parameters in distributed systems described by partial differential equations is discussed. The discrete-scanning observations are performed by an optimal selection of measurement data from spatially fixed sensors. In the adopted approach, the sensor scheduling problem is converted to a constrained optimal control problem. In this framework, the control value represents the selected sensor configuration. Thus the control variable is constrained to take values in a discrete set and switchings between sensors may occur in continuous time. By applying the control parameterization enhancing transform technique, a computational procedure for solving the optimal scanning measurement problem is obtained. The numerical scheme is then tested on a computer example regarding an advection-diffusion problem.     

伪码辅助载波的高精度角度测量方法

研究了采用短基线时高精度角度测量的问题.在基线长度受限制的情况下,为实时完成高精度的角度测量,需采用高频载波和准确确定载波的整周数.提出了一种基于伪码辅助载波的高精度角度测量方法,在伪码粗测的基础上,利用载波来完成高精度的角度测量.导出了该方法下无整周模糊的条件以及确定整周数的判据,载波频率的选择不受基线长度的制约,可以实时完成整周数求解.     

On the determination of optimal costly measurement strategies for linear stochastic systems

This paper presents the formulation of a class of optimization problems dealing with selecting, at each instant of time, one measurement provided by one out of many sensors. Each measurement has an associated measurement cost. The basic problem is then to select an optimal measurement policy, during a specified observation time interval, so that a weighted combination of “prediction accuracy” and accumulated “observation cost” is optimized. The current analysis is limited to the class of linear stochastic dynamic systems and measurement subsystems. The problem of selecting the optimal measurement strategy can be transformed into a deterministic optimal control problem. An iterative digital computer algorithm is suggested for obtaining numerical results. It is shown that the optimal measurement policy and the associated “matched” Kalman-type filter can be precomputed, i.e. specified before the measurements actually occur. Numerical results for a third-order system with two possible measurements are presented.