Linear relations betweenE-functions and Bessel functions

In this paper, some new linear relations for MacRobert'sE-Functions are established. They are formulae (1), (10), (15), (20), (22) and (28) below. For the definitions and properties of these functions, the reader is referred to MacRobert, “Functions of a Complex Variable” (3rd ed., London 1946), p. 348. This work will be denoted by the letters C.V. Also some expansions of Bessel Functions are deduced.     

Effect of flow on quasi-one-dimensional acoustic wave propagation in a variable area duct of finite length

The general equation for the velocity potential of quasi-one-dimensional acoustic wave motion in a variable area, finite duct with one-dimensional flow is derived by using a perturbation technique. The non-linear second-order partial differential equation is linearized and then solved, by either a power series expansion method or the Runge-Kutta fourth-order method, for harmonic time dependence. The boundary condition taken at the duct mouth is that of matching the impedance of the duct sound field to that of the radiation field at the duct opening. Three axial Mach number variations along the duct axis are considered and the results obtained are compared with those for the case of constant Mach number, to determine the influence of the axial velocity gradient on sound propagation. The effect of flow on the radiation impedance is also considered.     

Spectroscopic investigations and electrical properties of PVA/PVP blend filled with different concentrations of nickel chloride

Films of PVA/PVP blend (50/50) filled with different concentrations of NiCl₂ were prepared by casting method. The prepared films were investigated by different techniques. XRD scans demonstrated that the peak intensity at 2θ≈20° decreased and the band width increased with increase in the concentrations of NiCl₂ content, which implied decrease in the degree of crystallization and hence causes increase in the amorphous region. UV-vis analysis revealed that the values of the optical band gap are affected with increase in NiCl₂ content. This indicates the formation of charge transfer complexes between the polymer blend and the filler. The rise of conductivity is significant with increased concentration of NiCl₂ filler; this reveals an increase in degree of amorphosity. AC conductivity (σ_ac) behavior of all the prepared films was investigated over the frequency range 42 Hz-5 MHz and under different isothermal stabilization in the temperature range 313-393 K. It suggests that the hopping mechanism might be playing an important role in the conduction process in high frequency region. The dielectric behavior was analyzed using dielectric permittivity (ε´, ε″) dielectric loss tangent (tan δ) and electric modulus (M″). The decrease in dielectric permittivity was observed with increase in the concentration of NiCl₂ filler. This suggests the role of NiCl₂ as filler to improve the electrical conductivity of PVA/PVP blend.     

Bestimmung des gerichteten spektralen Emissionsgrades von Feststoffen im Wellenlängenbereich von 2,5 µm bis 45 µm bei Temperaturen zwischen 80°C und 350°C

Zusammenfassung Der beschriebene Meßaufbau gestattet, den gerichteten spektralen Emissionsgrad im Wellenlängenbereich von 2,5 µm bis 45 µm bei Temperaturen zwischen 80°C und 400°C zu bestimmen. Die Proben müssen für Strahlung der untersuchten Wellenlänge undurchlässig sein und einen Durchmesser zwischen 50 mm und 90 mm bei einer Dicke bis zu 10 mm haben. Die Standardabweichung bei der Bestimmung des spektralen Emissionsgrades beträgt 1,0%. Zur Bestimmung des spektralen Emissionsgrades werden die spektralen Strahldichten des Schwarzen Körpers und der Probenoberfläche bei bekannter Temperatur mit einem Fourierspektrometer verglichen. Die problematische Bestimmung der Probenoberflächentemperatur geschieht mittels der Fourierschen Wärmeleitungsgleichung mit der bekannten, gesondert zu bestimmenden Wärmeleitfähigkeit der Probe und dem berechneten Energieverlust der Oberfläche an die Umgebung durch Leitung, Konvektion und Strahlung. Zur Überprüfung der Meßergebnisse wurde der senkrechte spektrale Emissionsgrad an drei beschichteten Glasproben gemessen, an denen bei einem internationalen Vergleich der Gesamtemissionsgrad gemessen wurde. Die aus den hier bestimmten spektralen Werten berechneten senkrechten Gesamtemissionsgrade zeigten eine sehr hohe Übereinstimmung mit den Werten aus dem internationalen Vergleich und anderen Meßwerten.

---

Determination of the directional spectral emissivity of solids in the spectral range from 2.5 µm to 45 µm at temperatures between 80°C and 350°C

The measuring set-up described allows the directional spectral emissivity to be determined in the wavelength range from 2.5 ¶m to 45 ¶m at temperatures between 80°C and 400°C. The samples must be opaque to radiation of the wavelength investigated. They must have a diameter of between 50 mm and 90 mm and be up to 10 mm thick. The uncertainty of the determination of the spectral emissivity amounts to 1.0%. To determine the spectral emissivity, the spectral radiances of black-body and sample surface are compared at known temperature using a Fourier spectrometer. The problematic determination of the sample surface temperature is carried out on the basis of Fourier's equation of thermal conduction, making use of the known thermal conductivity of the sample (which must be separately determined) and the calculated energy loss from the surface to the environment by conduction, convection and radiation. To check the measurement results, the vertical spectral emissivity was measured on three coated glass samples whose total emissivity had been measured in an international comparison. The total vertical emissivities calculated from the spectral values determined here show very good agreement with the values obtained in the international comparison and with other measurement values.

     

Determination of plastic stress-strain behavior by digital-image-processing techniques

This work explores the application of digitalimage-processing techniques to the measurement of large plastic strains. Two sample problems have been selected, namely the uniform tensile deformation of aluminum-sheet metal strips and the post-necking deformation of copper circular rods. Images of these gridded metallic test pleces were captured, digitized and analyzed in a fully computerized way to evaluate strain distributions, anisotropic parameters and plastic stress-strain flow curves. For post-necked test pieces, Bridgman stress correction has been easily applied by defining the neck profile contour from the automated processing of digitized images. Results compare satisfactorily with those based on displacements measured by conventional microscopy. The presented technique, with added improvements, can consititute a viable one for accurate and fully computerized measurement of large deformations.     

Chemical and Electrochemical Preparation for Co(II) Complexes of Some Novel Pyridine-2-(1H)-Thione Ring Fused Cycloalkane Derivatives

Anodic oxidation of cobalt and copper metals in an anhydrous acetone solution of pyridine-2-(1H)-thione-3-cyano-4-(2-bromophenyl)-5,6-ring fused cycloheptane (HL¹) and its derivatives, (HL²), (HL³), (HL⁴), (HL⁵), (HL⁶), (HL⁷), (HL⁸), and (HL⁹) yields complexes of composition [M(L)₂·(H₂O)₂]·n H₂O and [M(L)₂·(acetone)₂], where M = Co(II) or Cu(II) and L is the ligand. Also, reaction of an aqueous ethanolic solution of Co(Ac)₂·2H₂O with the previous ligands was prepared. Elemental analysis, and infrared and electronic spectral data are presented to confirm the formulation of the amorphous complexes. The spectral data indicate that the ligands are coordinated to the metal via the thioenol sulfur atom and the nitrogen atom of cyano groups. The ligands reacts in the enol form through the anodic dissolution of the ligands or during the reaction with metal salts. The ligand field parameters and crystal field splitting energies, Δ_o, for different cobalt metal complexes were calculated.     

Facile Synthesis of Thiophene- and 1,3,4-Thiadiazole-Based Heterocycles

Treatment of 3-cyanoacetylpyrazole derivative 1 with phenyl isothiocyanate in potassium hydroxide at room temperature followed by α-haloketones 4a–d and hydrazonoyl halides 10a–e gave the corresponding pyrazolylthiophene 6a–d and pyrazolyl-1,3,4-thiadiazole 12a–e derivatives, respectively.