基于LabWindows/CVI的多线程测控软件设计技术

多线程技术是W in32操作系统的一项重要软件技术。CVI 6.0及其以后版本提供了线程池和异步定时器两种多线程运行机制,为测控软件的设计开发带来了一次技术飞跃。文中结合测控软件设计实例,详细介绍了在CVI平台下多线程编程技术的应用方法。     

Metal complexes of 2-hetarylindandiones-1,3

The chelate and molecular complexes of 2-(2-benzazolyl, perimidyl)-indandiones-1,3 were synthesized for the first time. The structures of the ligands (tautomeric forms) and complex compounds were determined from the X-ray diffraction, ¹H, ¹³C NMR, and IR data and the quantum-chemical calculations (RHF SCF in 6-31 G** basis).     

Simulation of interaction between a rarefied gas jet and an obstacle by the methods of molecular dynamics

An efficient method of direct numerical simulation is proposed. The steady-state flow field generated by the impingement of a gas jet on a wall is studied as an example. The numerical results obtained during this study are in good agreement with the numerical solutions of other authors.     

Electrochemical synthesis of niobium compounds in anodic dissolution of ferroniobium in methanol

Anodic dissolution of ferroniobium in anhydrous methanol in the presence of sodium methylate was studied. The possibility of recovering pure hexamethoxyniobate from the electrolyzate and its conversion into niobium methylate with an iron content not exceeding 0.01% was analyzed.     

Synthesis and structure of unsymmetrical cross-conjugated dienones with thienyl substituents

By condensation of thiophenecarbaldehyde and m-nitrobenzaldehyde with furyl-, thienylmethylenecyclohexanones in basic medium 2-(het)arylmethylene-6-thienylmethylenecyclohexanones were prepared. Under the conditions of acid catalysis analogously built dienones were synthesized containing 5-nitrothiophene fragment. Based on the data of IR and ¹H NMR spectroscopy their E,E-configuration was established.     

Studies of physical phenomena in semiconductor nanostructures using samples with laterally nonuniform layers. Photoluminescence of structures with n-type δ-doped layers

Photoluminescence of a structure based on GaAs with δ-doped n-type layers is studied experimentally at 77 K in the context of a previously suggested spectral-correlative method for investigating semiconductor structures with laterally nonuniform layers. This method makes it possible to study (for the same sample) the features of the observed multicomponent photoluminescence spectrum in relation to two parameters, i.e., the distance between the δ-doped layers and the width of a narrow InGaAs quantum well located between these layers. The results obtained make it possible to relate the observed exponential increase in the intensity of photoluminescence from the region of δ-doped layers as these parameters are varied to the variation in the ratio between the concentration of the holes laterally localized in the minimums of the fluctuation potential and that of free two-dimensional holes. An effect of stabilization of the energy position of the photoluminescence spectral lines is observed; this effect is related to the localization of holes in the potential well between the δ-doped layers. The experimental data obtained are consistent with the results of our numerical calculations.     

A new scheme for bidirectional WDM-PON using upstream and downstream channels generated by optical carrier suppression and separation technique

We propose a new bidirectional dense wavelength-division-multiplexing (DWDM)-based passive optical network using optical carrier suppression and separation technique to generate both upstream and downstream wavelength channels from a single laser. Thirty-two DWDM channels have been generated, and symmetric 10-Gb/s data transmission of a wavelength pair has been demonstrated.     

Self-excitation and synchronization in a multibeam microwave generator with electron-oscillator flows

Self-excitation and radiation of a multibeam spatially distributed microwave generator with centrifugal electrostatic focusing are considered. The transition to equivalent self-oscillators with slowly varying amplitudes and phases is substantiated. Examples of the directivity patterns and level lines of the field radiated in the master-slave and mutual synchronization modes and observed in a given section are presented.     

Target Level Method in Linear Multi-Criterion Problems

We consider the target level method for solving linear multi-criterion maximization problems. The method finds an efficient (Pareto-optimal) vector estimate that is closest in the Chebyshev metric to the target level point specified by the decision maker. The proposed method describes (parametrizes and approximates) the efficient set. In the linear case the number of scalar optimization problems needed to describe the set of efficient vector estimates is substantially reduced. A formula is derived which, under certain conditions, can be used to compute efficient vector estimates without solving any optimization problems. An algorithm based on these results is proposed for two-criterion problems.