A REDUCED VAPOR PRESSURE EQUATION BASED ON THE THEOREM OF CORRESPONDING STATES

A reduced vapor pressure equation based on the theorem of corresponding states is proposed in this work by the use of the third parameter to and the fourth parameter X. This equation yields an overall average absolute deviation of 1.09% for 111 normal fluids involving a total of 6968 vapor pressure data points, and 0.67% for 20 polar fluids involving a total of 1516 data points, respectively. A relationship of estimating acentric factors is obtained by applying the reduced vapor pressure equation at the normal boiling point. This relationship is very accurate for the prediction of the values of the acentric factor     

NUMERICAL SIMULATION OF SWIRLING FLOW IN A CYCLONE CHAMBER

The ability to predict the influence of design parameters on the aerodynamics of cyclone chambers flows is of prime concern in furnace engineering and a number of high temperature processes. The two-dimensional Los Alamos SOLA prediction technique has been extended to include the computation of an axisymmetric swirling flow. The transient Navier-Stokes equations of an incompressible fluid are solved via their associated finite difference equations, directly in terms of the primitive pressure-velocity variables. For this, a short simple computer code has been developed, using a laminar flow simulation with ‘free slip’ wall boundary conditions. Predictions show that a useful characterization of the flowfield is now available. The simplified code represents a basic tool, to which user-oriented complexities and sophistications can be added later as required     

NUMERICAL SIMULATION OF SWIRLING FLOW IN A CYCLONE CHAMBER

The ability to predict the influence of design parameters on the aerodynamics of cyclone chambers flows is of prime concern in furnace engineering and a number of high temperature processes. The two-dimensional Los Alamos SOLA prediction technique has been extended to include the computation of an axisymmetric swirling flow. The transient Navier-Stokes equations of an incompressible fluid are solved via their associated finite difference equations, directly in terms of the primitive pressure-velocity variables. For this, a short simple computer code has been developed, using a laminar flow simulation with 'free slip' wall boundary conditions. Predictions show that a useful characterization of the flowfield is now available. The simplified code represents a basic tool, to which user-oriented complexities and sophistications can be added later as required     

A NOTE ON APPROXIMATING THE DISTRIBUTION OF THE DURBIN-WATSON STATISTIC

Abstract. This note considers approximating the distribution of the d statistic proposed by Durbin and Watson (1950,1951) by four-parameter Pearson distribution. It is shown that the approximations are remarkably close to the exact distributions for four sets of published data considered by Durbin and Watson (1971).     

A NOTE ON THE COMPUTATION OF THE BAYESIAN DECOMPOSITION OF A TIME SERIES

Abstract. The purpose of the present note is to propose an efficient algorithm for the Bayesian decomposition of a time series, utilizing some results recently developed in the area of methods of regularization of certain integral equations. Within this framework, it is shown how the special structure of the problem can be exploited so that a considerable gain in computational efficiency over existing procedures can be obtained.     

A NOTE ON THE EMBEDDING OF DISCRETE-TIME ARMA PROCESSES

Abstract. Let {X_n, n= 0, 1, 2,…} be a discrete-time ARMA(p, q) process with q < p whose autoregressive polynomial has r (not necessarily distinct) negative real roots. According to a recent result of He and Wang (On embedding a discrete-parameter ARMA model in a continuous-parameter ARMA model. J. Time Ser. Anal. 10 (1989), 315–23) there exists a continuous-time ARMA (p', q') process {Y(t), t≥0} with q' < p'=p+r such that {Y(n), n= 0, 1, 2,…} has the same autocorrelation function as {X_n}. In this paper we show that this result is false by considering the case when {X_n} is a discrete-time AR(2) process whose autoregressive polynomial has distinct complex conjugate roots. We identify the proper subset of such processes which are embeddable in a continuous-time ARMA(2, 1) process. We show that every discrete-time AR(2) process with distinct complex conjugate roots can be embedded in either a continuous-tie ARMA(2, 1) process or a continuous-time ARMA(4, 2) process, or in some cases both. We derive an expression for the spectral density of the process obtained by sampling a general continuous-time ARMA(p, q) process (with distinct autoregressive roots) at arbitrary equally spaced time points. The expression clearly shows that the sampled process is a discrete-time ARMA (p', q') process with q' < p.     

几种光敏剂光敏氧化效率的比较

光敏氧化效率是由敏化剂分子吸收光量子数及其产生单重态氧的量子产率决定的,这要求敏化剂的吸收光谱同光源的发射光谱很好地匹配。本文报道竹红菌甲素匹配高压钠灯有效地产生单重态氧,高效光敏氧化一系列具有不同反应活性的底物,成为单重态氧化学中一个新的光敏氧化体系。     

A NOTE ON THE DISTRIBUTIONS OF NON-LINEAR AUTOREGRESSIVE STOCHASTIC MODELS

Abstract. It is shown that an ergodic stationary non-linear autoregressive stochastic process, perturbed by a white noise process with symmetric distributions, has symmetric stationary distributions if and only if the regression function is skew-symmetric. The implications of this observation are discussed.     

A METHODOLOGICAL NOTE ON THE DISAGGREGATION OF TIME SERIES TOTALS

Abstract. This paper sheds new light on a generalized least squares approach for disaggregating a series of time series totals to estimate an underlying unaggregated series. By reinterpreting the generalized least squares problem as a time series prediction problem we can produce considerable computational savings relative to standard least squares approaches. Our reinterpretation gives us insight into the nature of the matrices which need to be inverted to compute the disaggregates.     

旋风分离器斜三通管损坏原因分析及措施

针对斜三通管在水压试验过程中出现裂纹的现象,从设备结构和制造方面进行分析,通过增加加强圈等措施,顺利完成了水压试验,满足了现场生产需要。     

A FURTHER NOTE ON THE DETECTION OF GRANGER INSTANTANEOUS CAUSALITY

Abstract. The purpose of this paper is to demonstrate that it is conceptually incorrect to examine the contemporaneous univariate residual cross-correlation between two time series in testing for the existence of instantaneous causality.     

NOTE ON THE HARDNESS OF GLAZES1

Method of measurement.—The apparatus used (figure 1) consisted of a hardened tungsten-steel point which was allowed to bear on the glaze surface for 3 min. under a pressure of 50 lbs. The hardness was then computed from the dimensions of the resulting indentation. Results were reproducible to about 5 per cent. (See table III.) The presence of ridges and bubbles in the glaze was the principal cause of discordant readings. Results and conclusions.—The enamels show the lowest and the porcelain glazes the greatest hardness, while the whiteware glazes occupy an intermediate position. The difference in hardness between the enamels and the whiteware glazes is quite marked. There is also a rather well defined difference between the whiteware and the porcelain glazes, but not a sharp separation between the lower and the higher fired porcelain glazes. Enough evidence has been accumulated to show that increased firing of the same glaze will increase the hardness. It appears also that increase in the alumina content brings about greater hardness.     

利用立式旋风炉附烧处理铬渣工业化试验

针对铬盐厂多年积存的大量含Ｃｒ＾６＋的有毒铬渣处理问题,进行了利用立式旋风炉附烧处理铬渣的实验,实验证明,利用电站旋风炉进行铬渣附烧,在热电联产的同时,实现了铬渣的彻底解毒。     

吸气式浮选旋流器内部流场理论分析

利用Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程对吸气式浮选旋流器内部流场的速度分布及压力分布作了系统的理论分析研究．并对该方程进行了简化,合理地确定边界条件,根据流动特性对其加以修正,使其客观地反映了旋流器内部流场的真实流动状态,从而得出旋流器的分界面位置,旋流器中心存在空气柱,其大小取决于溢流管的直径、入料速度及入料压力．这一结论对旋流器内物料的分级性能具有决定性作用．     

NOTE ON THE EFFECT OF TIME ON THE DRYING SHRINKAGE OF CLAYS1

The drying shrinkage or clays were studied to determine how quickly different types can be dried and to note whether or not the time of drying influences the amount of shrinkage. Three shales, two ball clays and one fire-clay were tested and the following conclusions reached: (a), drying time depends largely on water content; (b), the structure of the clay is an important factor; (c), the amount of total shrinkage is proportional to the water content; (d), the amount of total shrinkage is not influenced by the rapidity of drying.     

NOTE ON THE VAPOR ABSORPTION OF A FIRED EARTHENWARE BODY1

Specimens of an earthenware body fired at three temperatures were placed over a 10% sulphuric acid solution for 36 days and the gain in weight determined. Up to a certain limit of porosity the absorption is proportional to the porosity, but the body with the highest absorption, 20.25% took up a relatively higher amount of water. With an absorption of 8.81%, the maximum amount of water vapor taken up was 0.13%. With 10.8% absorption the water vapor taken up was 0.16 and with 20.25% absorption it reached 0.54%.