Problems of Wastewater Treatment and Methods of Solving Them

The studies show that in the combined use of biological and chemisorption stages of treatment, a deeper degree of removal of industrial pollutants from wastewaters is attained. The chemisorption stage allows stabilizing the treatment process in different concentration-temperature drops and increasing the degree of removal of synthetic surfactants (SSF), petroleum products, and nitrogen compounds. The possibility of regulating the selectivity of the treatment process by varying the composition of the chemisorption material is demonstrated.     

Contention-conscious transaction ordering in multiprocessor DSP systems

This paper explores the problem of efficiently ordering interprocessor communication (IPC) operations in statically scheduled multiprocessors for iterative dataflow graphs. In most digital signal processing (DSP) applications, the throughput of the system is significantly affected by communication costs. By explicitly modeling these costs within an effective graph-theoretic analysis framework, we show that ordered transaction schedules can significantly outperform self-timed schedules even when synchronization costs are low. However, we also show that when communication latencies are nonnegligible, finding an optimal transaction order given a static schedule is an NP-complete problem, and that this intractability holds both under iterative and noniterative execution. We develop new heuristics for finding efficient transaction orders, and perform an extensive experimental comparison to gauge the performance of these heuristics.     

Enhanced Photoelectrochemistry in CdS/Au Nanoparticle Bilayers

Three different configurations of Au‐nanoparticle/CdS‐nanoparticle arrays are organized on Au/quartz electrodes for enhanced photocurrent generation. In one configuration, Au‐nanoparticles are covalently linked to the electrode and the CdS‐nanoparticles are covalently linked to the bare Au‐nanoparticle assembly. The resulting photocurrent, φ = 7.5 %, is ca. 9‐fold higher than the photocurrent originating from a CdS‐nanoparticle layer that lacks the Au‐nanoparticles, φ = 0.8 %. The enhanced photocurrent in the Au/CdS nanoparticle array is attributed to effective charge separation of the electron–hole pair by the injection of conduction‐band electrons from the CdS‐ to the Au‐nanoparticles. Two other configurations involving electrostatically stabilized bipyridinium‐crosslinked Au/CdS or CdS/Au nanoparticle arrays were assembled on the Au/quartz crystal. The photocurrent quantum yields in the two systems are φ = 10 % and φ = 5 %, respectively. The photocurrents in control systems that include electrostatically bridged Au/CdS or CdS/Au nanoparticles by oligocationic units that lack electron‐acceptor units are substantially lower than the values observed in the analogous bipyridinium‐bridged systems. The enhanced photocurrents in the bipyridinium‐crosslinked systems is attributed to the stepwise electron transfer of conduction‐band electrons to the Au‐nanoparticles by the bipyridinium relay bridge, a process that stabilizes the electron–hole pair against recombination and leads to effective charge separation.     

Development of a Continuous Segmented Flow Tubular Reactor and the “Scale‐out” Concept – In Search of Perfect Powders

The synthesis of powders with controlled shape and narrow particle size distributions is still a major challenge for many industries. A continuous Segmented Flow Tubular Reactor (SFTR) has been developed to overcome homogeneity and scale‐up problems encountered when using batch reactors. Supersaturation is created by mixing the co‐reactants in a micromixer inducing precipitation; the suspension is then segmented into identical micro‐volumes by a non‐miscible fluid and sent through a tube. These micro‐volumes are more homogeneous when compared to large batch reactors leading to narrower size distributions, better particle morphology, polymorph selectivity and stoichiometry. All these features have been demonstrated on single tube SFTR for different chemical systems. To increase productivity for commercial application the SFTR is being “scaled‐out” by multiplying the number of tubes running in parallel instead of scaling‐up by increasing their size. The versatility of the multi‐tube unit will allow changes in type of precipitate with a minimum of new investment as new chemistry can be researched, developed and optimised in a single tube SFTR and then transferred to the multi‐tube unit for powder production.     

Hot carrier analysis in low-temperature poly-Si thin-film transistors using pico-second time-resolved emission microscope

We have analyzed degradation of N-channel thin-film-transistor (TFT) under dynamic stress using a pico-second time-resolved emission microscope. We have successfully detected emission at pulse fall edge for the first time. Emission intensity increased with the decrease of pulse fall time. As the degradation depended on the pulse fall time, this dependence clearly illustrates that hot electrons are the dominant cause of the degradation under dynamic stress. Based on these dependences, we proposed a model considering electron traps in the poly-Si.     

Synthesis and Study of Alkaline-Earth Metal Uranoborates,AI I(BUO5)2·nH2O

Previously unknown compounds A^{I I}(BUO₅)₂·nH₂O (A^{I I} = Mg, Ca, Sr, Ba; n = 0-7) were synthesized. Their structure and thermal decomposition were studied by X-ray diffraction, IR spectroscopy, and thermal analysis.     

Thermal conductivity of doped PbTe-based solid solutions with off-center impurities

The coefficients of thermopower and electrical and thermal conductivity in the PbTe_0.8Se_0.1 S _0.1 solid solution with electron concentration (4.6–54) × 10¹⁸ cm^?3 are studied in the range of 85–300 K (and in some cases up to 700 K). The temperature dependences of electrical and thermal conductivity indicate that the low-temperature electron and phonon scattering initiated by the off-center impurity of sulfur exists. The temperature dependences of the electronic and lattice components of thermal conductivity are calculated in the approximation of a parabolic spectrum and electron scattering by acoustic phonons and neutral substitutional impurities. The lattice thermal conductivity is found to have a feature in the form of a shallow minimum in the range of 85–250 K. A similar feature, while not so clearly pronounced, is found to exist also in Pb_1?x Sn_xTe_1?x Se_x alloys (x≥0.15) with an off-center tin impurity. An analysis of the possible origins of this effect suggests that, at low temperatures, the Lorentz numbers L of the materials under study are smaller than the L₀ numbers employed which correspond to the above scattering mechanisms. The cause of the decrease in L is related to electron scattering at two-level systems, a mechanism whose effect grows with increasing electron energy. An analysis of experimental data obtained at high temperatures, as well as on undoped samples with the lowest possible carrier concentrations, yields the values of L for samples with different electron densities. The minimum value L/L₀ = 0.75 is obtained for a lightly doped sample at ～130 K.     

Performance of decorrelating receivers in multipath Rician fading channels

This letter focuses on the performance analysis of the decorrelating receiver in multipath Rician faded CDMA channels. M-ary QAM scheme is employed to improve the spectral efficiency. Approximate expressions are first derived for the two performance indexes: the average symbol error rate (SER) and the average bit error rate (BER) when the decorrelating-first receiver perfectly knows the channel information of the user of interest. To achieve desirable closed-form expressions of the SER and the BER, we exploit results in large system analysis and make assumptions of a high signal-to-interference ratio (SIR) and/or a small Rician K-factor. To measure the receiver performance in the practical scenario, we further derive expressions to approximate the average SER and BER of the decorrelating-first scheme with channel uncertainty. Simulation results demonstrate that the analytical results can also be employed to evaluate the performance of the combining-first receiver.     

Electrical and photoelectric properties of electrochemically fabricated SnO2/Cd0.4Zn0.6S/CdTe solar cells

Solar cells based on SnO₂/Cd_0.4Zn_0.6S/CdTe heterostructures are fabricated by electrochemical deposition, and the dependences of their electrical and photoelectric properties on the thermal annealing conditions are studied. It is shown that thermal annealing reduces the tunnel currents by almost two orders of magnitude. The best conditions of thermal annealing are determined (t = 300°C and τ = 9 min). These conditions provide the highest photosensitivity of the heterostructures under study (I _sc ≈ 21.2 mA/cm², U _oc ≈ 813 mV, and η = 14.7%).     

Towards intelligent dressing

The aim of this article is to state the principles of an intelligent monitoring and control system for the grinding machine, comprising the dressing process as well as grinding stability.