Thermal storage efficiencies of two solar saltless water ponds

A comparative study between two types of solar ponds is presented. The first type has its free surface covered by a thin layer of transparent paraffin oil. The second type is covered by transparent glass floating devices. Each device disposes an air-vacuum chamber. The free water surface between these devices is covered by transparent paraffin oil also. The thermal storage efficiency of each pond is estimated during two time periods: between sunrise and sunset and from midnight to midnight. The calculated efficiency between sunrise and sunset corresponds to the average transmittance–absorptance product. This is estimated using linear regression and also a maximum likelihood identification technique. The behavior of the system was studied by solving numerically the heat transfer equations of the system. Also an ARMAX (AutoRegressivie Moving Average with eXogenous signal) model allowing the assessment of its performance was presented. This efficiency is larger for the first pond during the sunrise to sunset period and smaller when calculated from midnight to midnight. Thus, the first type of pond could be preferred for a use just after the sunset of the same day, while the second for use after one or more days of heat storage.     

Static and pulsed pressures measured using electrically conducting rubbers

A method of measuring static and pulsed pressures using electrically conducting rubber sensors is proposed. The method is based on a change in the volume resistivity of a filled rubber under the action of external pressure. The pressure-induced change in resistance of the rubber sensor is proportional to the applied pressure and can be measured by a bridge circuit. Using this method, it is possible to evaluate the degree of homogeneity of the pressure distribution over a solid surface. This is achieved by distributing rubber sensors over the given surface.     

Mechanical equipment of the Tashlyk pumped-storage hydroelectric station and Aleksandrovka hydro development of the Southern Ukraine power complex

Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 6–7, November, 1989.     

Parametric modeling of somatosensory evoked potentials

In this paper, we examine methods of characterizing somatosensory evoked potentials (SEP's) in both the time and frequency domains. We have found that the truncated impulse response (TIR) method produced an accurate time domain model of the SEP signals at model orders greatly reduced from the original state space matrix. The TIR method was valuable for smoothing signals that were slightly corrupted by noise. In this case, the simulated data sequence was close to the original data sequence in the mean squared error sense. For signals that were greatly corrupted by noise, the TIR method was not able to perform as well. Therefore, the TIR method was not a feature extraction method but was valuable for data simulation. In the frequency domain, we have used the autoregressive moving average model (ARMA) to parameterize the SEP signal. An overdetermined set of Yule-Walker equations was created to determine the autoregressive (AR) parameters of the original data with the model order established by the singular value decomposition. From these AR parameters, a residual time series was generated which was used to find the moving average parameters. The resulting ARMA model was used to produce a simulated data sequence. The frequency domain characteristics of the simulated sequence and the corresponding power spectral density of the ARMA filter were very close to the periodogram of the original data sequence. Accurate parameterization was achieved for the SEP waveforms at low filter lengths.     

Biochemical oxidation of caprolactam-containing wastewater from the production of synthetic fibres

Conclusions The chemical mutagenesis method is recommended for use in local purification installations for cleaning up of caprolactam-containing wastewater.Use of this method permits one to carry out a biochemical clean-up of wastewater having a caprolactam content up to 600 mg/liter while increasing the oxidative power of the aeration tank by a factor of two.Translated from Khimicheskie Volokna, No. 6, p. 46, November–December, 1985.     

Development of Free-Electron x-Ray Lasers on the TESLA Test Accelerator (DESY, Germany)

The program for developing free-electron x-ray lasers at TESLA started in 1994. The plan is to use the TESLA test accelerator to develop an x-ray laser with minimum wavelength 0.1–6 nm. The first phase of the project was successfully completed in 2001. At saturation, the laser produces ultrashort 30–100 fsec, gigawatt, radiation pulses. The wavelength can be tuned smoothly over the range 80–120 nm.     

Simulation of the Accelerating Systems of Cyclotrons for Applications

The results of a comparative numerical investigation of three types of resonator systems of a cyclotron for acceleration of negative hydrogen and deuterium ions up to maximum energy 30 and 15 MeV, respectively, are presented. It is shown that a vertical system with two half-wave resonators excited in-phase has the smallest active losses and the smallest differential of the amplitude of the accelerating voltage along the edge of the dees and is effective for accelerating particles at dual working frequencies.     

Catalytic reduction of N2O with CH4 and C3H6 over Ag–Rh/Al2O3 bimetallic catalyst in the presence of oxygen

A study of nitrous oxide (N₂O) reduction with methane (CH₄) and propene (C₃H₆) in the presence of oxygen (5%) over Ag/Al₂O₃, Rh/Al₂O₃ and Ag–Rh/Al₂O₃ catalysts, with Ag and Rh loadings of 5 wt% and 0.05 wt% respectively, has been performed. From the results, it was observed that the Ag–Rh bimetallic catalyst was the most active for both nitrous oxide removal (more than 95%) and hydrocarbon oxidation. This high activity seems to be connected with a synergistic effect between Ag and Rh. The findings from X‐ray diffraction and X‐ray photoelectron spectroscopy studies showed also, that there were no strong interactions (eg alloying) between Ag and Rh. Copyright © 2005 Society of Chemical Industry