无穷域三重积分优化二次式数值算法

本文采用步长三等分法,给出三重积分integral from n=a to ∞(integral from n=b to ∞(integral from n=c to ∞(f(x,y,z)dx)))dydz的优化二次式数值积分法,它在迭代计算时免去了重复计算,加速达到近似值精度。并给出了误差估计式。     

Sensitivity of the backscattering Mueller matrix to particle shape and thermodynamic phase

The Mueller matrix (M) corresponding to the phase matrix in the backscattering region (scattering angles ranging from 175 degrees to 180 degrees) is investigated for light scattering at a 0.532-microm wavelength by hexagonal ice crystals, ice spheres, and water droplets. For hexagonal ice crystals we assume three aspect ratios (plates, compact columns, and columns). It is shown that the contour patterns of the backscattering Mueller matrix elements other than M11, M44, M14, and M41 depend on particle geometry; M22 and M33 are particularly sensitive to the aspect ratio of ice crystals. The Mueller matrix for spherical ice particles is different from those for nonspherical ice particles. In addition to discriminating between spherical and nonspherical particles, the Mueller matrix may offer some insight as to cloud thermodynamic phase. The contour patterns for large ice spheres with an effective size of 100 microm are substantially different from those associated with small water droplets with an effective size of 4 microm.     

Compact varactor-tuned meander line monopole antenna for DVB-H signal reception

A compact varactor-tuned meander line monopole antenna for DVB-H signal reception is presented. The operating frequency of the antenna is continuously tuned over the frequency range of the DVB-H standard 470-702 MHz. The antenna has an omnidirectional radiation pattern and covers the frequency range with requisite impedance bandwidth and gain level. The antenna element occupies a very small volume (0.7 cm³ ) and can be used in 40 x 100 x 10 mm devices.     

Electrocatalytic oxidation of some anti-inflammatory drugs on a nickel hydroxide-modified nickel electrode

The electrocatalytic oxidation of several anti-inflammatory drugs (mefenamic acid, diclofenac and indomethacin) was investigated on a nickel hydroxide-modified nickel (NHMN) electrode in alkaline solution. This oxidation process and its kinetics were studied using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy techniques. Voltammetric studies indicated that in the presence of drugs, the anodic peak current of low-valence nickel species increases, followed by a decrease in the corresponding cathodic current. This pattern indicates that drugs were oxidized on the redox mediator immobilized on the electrode surface via an electrocatalytic mechanism. A mechanism based on the electrochemical generation of Ni(III) active sites and their subsequent consumption by drugs was also investigated. The corresponding rate law under the control of charge transfer was developed and kinetic parameters were derived. In this context, the charge-transfer resistance accessible both theoretically and through impedancemetry was used as a criterion. The rate constants of the catalytic oxidation of drugs and the electron-transfer coefficients are reported. A sensitive, simple and time-saving amperometric procedure was developed for the analysis of these drugs in bulk form and for the direct assay of tablets, using the NHMN electrode.     

Temporal and Spatial Variation of Fungal Concentrations in Indoor Air

The aim of this study was to determine temporal and spatial variation of airborne concentrations of viable fungi in 2 single-family houses during the period of the year that such levels are mostly determined by indoor sources. One of the subject residences had moisture problems (the index residence), the other did not have any moisture problems (the reference residence). The concentrations of viable fungi in indoor air were determined a total of 6 times during the winter with 2 six-stage impactors (Andersen 10-800) in 2 rooms in both of the houses. The total concentrations of viable fungi and concentrations of Penicillium, Aspergillus, and Aspergillus versicolor     

Novel Online Diagnostic Analysis for In-Flight Particle Properties in Cold Spraying

In cold spraying, powder particles are accelerated by preheated supersonic gas stream to high velocities and sprayed on a substrate. The particle velocities depend on the equipment design and process parameters, e.g., on the type of the process gas and its pressure and temperature. These, in turn, affect the coating structure and the properties. The particle velocities in cold spraying are high, and the particle temperatures are low, which can, therefore, be a challenge for the diagnostic methods. A novel optical online diagnostic system, HiWatch HR, will open new possibilities for measuring particle in-flight properties in cold spray processes. The system employs an imaging measurement technique called S-PTV (sizing-particle tracking velocimetry), first introduced in this research. This technique enables an accurate particle size measurement also for small diameter particles with a large powder volume. The aim of this study was to evaluate the velocities of metallic particles sprayed with HPCS and LPCS systems and with varying process parameters. The measured in-flight particle properties were further linked to the resulting coating properties. Furthermore, the camera was able to provide information about variations during the spraying, e.g., fluctuating powder feeding, which is important from the process control and quality control point of view.     

Tunable microwave devices using low-sintering-temperature screen-printed barium strontium titanate (BST) thick films

A tunable microwave phase shifter composed of a low-sintering-temperature, screen-printable barium strontium titanate (BST) film and silver metallization was fabricated on an alumina substrate and co-fired at 900 °C for 3 h. The dielectric properties of the films were characterized in a frequency range of 0.8–8 GHz using scattering parameter measurements and a quasi-static coplanar waveguide transmission line model. The temperature dependency of the films was measured through capacitance measurements in a frequency range of 0.5–2.5 GHz. The figure of merit (phase shift/dB of insertion loss) of the phase shifter was found to be 14.6 at 3 GHz with an applied bias field strength of 2.5 V/μm. The performance of the phase shifter is briefly discussed and compared with other phase shifters fabricated by direct screen-printing of BST films.     

Thermoplastic 0–3 Ceramic–Polymer Composites With Adjustable Magnetic and Dielectric Characteristics for Radio Frequency Applications

Magnetic and electrical properties of thermoplastic ceramic-polymer 0–3 composites with Z-type hexaferrite, and MnZn ferrite inclusions were investigated. The complex permeability and permittivity were measured up to 1 GHz where maximum values of ɛ′_r=30.47 and μ′_r=4.32 and ɛ′_r=10.95 and μ′_r=1.80 were obtained for MnZn-ER182 and Co₂Z-ER182 composites with ∼44.7 vol% and 43.0 vol% filler loadings, respectively. MnZn and Co₂Z composites exhibit miniaturization factors as low as 0.09 and 0.23, together with reduced magnetic losses and frequency dispersion. The results indicate that the composites offer novel possibilities for wider feasible frequency bandwidth and adjustable impedance matching and magnetic and dielectric properties.