A new forecasting method for time continuous model of dynamic system

Usually a linear differential equation is used to represent continuous dynamic systems, but a linear difference equation is used to represent discrete dynamic systems. AGO is one of the most important characteristics of grey theory, and its main purpose is to reduce the randomness of data. A linear differential equation, instead of a linear difference equation, is used to replace the grey differential equation to analyze discrete systems in this paper. Approximating a k-order derivative by operating after spline curve fitting of 1-AGO data, a model is directly established by means of the least square method. ARIMA models are used to analyze the leading indicator in advance, and the Fourier series with suitably chosen values of parameters is used in the fitting of leading indicator. This model is called the GDM(2, 2, 1) model.     

Infrared radiation properties of methane at elevated temperatures

The spectral absorptivity of the v₃ and v₄ fundamental and the v₁ + v₄ combination bands of methane have been measured at low resolution for temperatures between 290 and 850 K. Spectral mean (narrow-band) parameters for the fundamental bands have been correlated from the Elsasser model, while total band absorptance data for all three bands have been correlated using the Edwards exponential wide band model. A total emissivity chart has been developed, based on the wide band absorption models.     

Syntheses of Bissydnone Derivatives and Studies of Their Biological Activities

A new method to prepare 3,3′-ethylenebissydnone (40%), 3,3′-tetramethylenebissydnone (37%) and 3,3′-hexamethylenebissydnone (43%) from the corresponding alkylene diamine with paraformaldehyde and potassium cyanide were investigated. Some new bissydone: ?3,3′-trimethylenebissydnone (6%), 3,3′-(4,4′-diphenyl)bissydnonylmethane (9%) and 3,3′-(4,4′-diphenyi)bissydnonyl ether (28%) were synthesized from the corresponding diamine, paraformaldehyde, sodium bisulfite and potassium cyanide. Biological test of 3,3′-(4,4′-diphenyl)bissydnonylmethane shows significant response for coronary dilgtion test, inhibition of collagen induced platelet aggregation and moderate carditropic response. 3,3′-(4,4′-Diphenyl)bissydnonyl ether also shows inhibition of collagen induced platelet aggregation and moderate carditropic response.     

Analysis of the longitudinal acoustic mode in linear aliphatic polyesters

Two intense modes are observed in the low-frequency Raman spectra of as-grown and annealed linear aliphatic polyester single crystals. Our experimental data in conjunction with theoretical normal mode calculations of several model oligomers reveal the two bands observed to be vibrations of the longitudinal acoustic mode type. The unbalanced mass units associated with the ester groups couple the transverse and longitudinal motions, giving rise to the multiple modes.     

On the dynamics near infinity of some polynomial mappings in

We construct the Green current for a random iteration of horizontal-like mappings in . This is applied to the study of a polynomial map with the following properties: i. infinity is f-attracting; ii. f contracts the line at infinity to a point not in the indeterminacy set. We study for such mappings the escape rates near infinity, i.e. the set of possible values of the function We show in particular that the set of possible values can contain an interval. On the other hand the Green current T of f can be decomposed into pieces associated to an itinerary defined by the indeterminacy points. This allows us to prove that exists ||T||-a.e. and we give its value in terms of explicit quantities depending on f.     

An extended hydrodynamic theory for particle coarsening—I: Theory

The asymptotic hydrodynamic approach to the mathematical solution of the kinetics of particle coarsening (Ostwald ripening), first proposed by Lifshitz and Slyozov and Wagner, has been extended and generalized. The coarsening rate equations in dimensionless forms have been separated into asymptotically determinate and indeterminate parts. The generalized evaluation of the asymptotically indeterminate part allows the consideration of coarsening processes that are more complicated than those involving power law type kinetics considered in previous studies. Further, the extended theory allows the determination of particle size distribution function and averaged particle coarsening kinetics even in cases where different physical processes occur at different size regimes within the same distribution of particles.     

Strip method for steady heat-conduction problems

Summary An approximate solution of heat-conduction problems can be obtained by the strip method. The method consists of an application of the finite-difference approximation in one physical coordinate and an analytic solution in other coordinates. A simple illustrative example is given and the result is compared with that obtained by the exact solution. By application of this method, an approximate solution is given for the steady heat conduction through a rectangular parallel composite wall with different rates of heat generation.     

Randomly oscillating turbulent channel flows

The velocity response to a sinusoidally oscillating pressure gradient is obtained for turbulent flow in a two-dimensional channel. The statistical relations between a spectrum of such pressure pulsations and the resulting spectrum of velocity oscillations are then written in terms of a spectral transfer function. This function, which incorporates the dynamic solution is complicated, but is well approximated with a simple expression.

---

Zusammenfassung Für turbulente Strömung in einem zweidimensionalen Kanal wird die Geschwindigkeitsverteilung, die durch einen sinusoidal oszillierenden Druckgradient verursacht ist,

---

Nomenclature A, B coefficients defined by comparison of Equation (1) with the appropriate dynamical equation foru - a half width of channel, or radius of pipe - b rate of increase of withy - c defined in Equation (31) - d defined in Equation (32) - f normalized spectral density of pressure oscillations - g normalized spectral density of velocity oscillations - h turbulent viscosity parameter defined in Equation (26) - I - K _n amplitude of the individual pressure oscillations - L ₁,L ₂,L ₃,L ₄,L ₅,L ₆ functions defined by Equations (18) (19) (20) (21) (24) (25) - m defined in Equation (30) - n frequency of pressure and velocity oscillations - p pressure - p _x defined in Equation (2) - R _p autocorrelation coefficient for pressure oscillations - R _u autocorrelation coefficient for velocity oscillations - t time - u axial velocity - w variable defined after Equation (15) - x axial position coordinate - y transverse position coordinate - z variable defined after Equation (15) - eddy diffusivity for momentum - dimensionless frequency, defined in Equation (7), for laminar case - _t dimensionless frequency, defined after Equation (16), for turbulent case - function defined in Equation (13) - laminar kinematic viscosity - variable displacement in time - fluid density - spectral transfer function - variable defined after Equation (16) This study was supported in part by the R. L. Albrook Hydraulic Laboratory of the Wash. State Univ. Division of Industrial Research.