A novel double-circuit-rotor balanced induction motor for improvedslip-energy recovery drive performance. I. Modeling and simulation

A new construction for the rotor windings of balanced wound-rotor induction motors employed in the slip energy recovery drives is proposed, in this paper, to reduce the time harmonics which are commonly generated in the machine. The proposed machine has a double-circuit in the rotor. One circuit is star connected while the other is delta connected. Each of these two circuits is connected to a diode-bridge rectifier to achieve a twelve-pulse operation characteristics. The main objective of this paper is to develop a new model which is capable of simulating the proposed machine, neglecting nonlinearities due to magnetic saturation, and its associated converters. Such a model is further complicated due to the presence of the two rotor circuits and their mutual interaction     

Gain clamping in two-stage L-band EDFA using a broadband FBG

A gain-clamped long wavelength band erbium-doped fiber amplifier (L-band EDFA) with an improved gain characteristic is demonstrated by simply adding a broadband conventional band (C-band) fiber Bragg grating (FBG) in a two-stage amplifier system. The FBG reflects backward C-band amplified spontaneous emission (ASE) from the second stage back into the system to clamp the gain. The gain is clamped at about 22.4 dB with a gain variation below 0.4 dB for input signal powers of -40 to -15 dBm. Compared with an unclamped amplifier of similar noise figure values, the small signal gain has improved by 2.4 dB due to the FBG which blocks the backward propagating ASE. At wavelengths from 1570 to 1600 nm, gain of the clamped amplifier varies from 19.4 to 26.7 dB. The corresponding noise figure varies by /spl plusmn/0.35 dB around 5 dB, which is not much different compared to that of the unclamped amplifier.     

ECRP: an energy-aware cluster-based routing protocol for wireless sensor networks

Energy conservation is the main issue in wireless sensor networks. Many existing clustering protocols have been proposed to balance the energy consumption and maximize the battery lifetime of sensor nodes. However, these protocols suffer from the excessive overhead due to repetitive clustering resulting in high-energy consumption. In this paper, we propose energy-aware cluster-based routing protocol (ECRP) in which not only the cluster head (CH) role rotates based on energy around all cluster members until the end of network functioning to avoid frequent re-clustering, but also it can adapt the network topology change. Further, ECRP introduces a multi-hop routing algorithm so that the energy consumption is minimized and balanced. As well, a fault-tolerant mechanism is proposed to cope up with the failure of CHs and relay nodes. We perform extensive simulations on the proposed protocol using different network scenarios. The simulation results demonstrate the superiority of ECRP compared with recent and relevant existing protocols in terms of main performance metrics.

     

Double-pass L-band EDFA with enhanced noise figure characteristics

A new double-pass long wavelength band erbium-doped fiber amplifier with enhanced noise figure characteristics is demonstrated by adding a short length of forward pumped erbium-doped fiber (EDF) in front of a double-pass amplifier. Compared with the conventional double-pass amplifier, the new amplifier provides noise figure improvement of about 0.8 to 6.0 dB over the flat-gain region from 1568 to 1600 nm. Since the optical circulator prevents the amplified signal and backward amplified spontaneous emission from propagating into the EDF, the population inversion of the input part of the amplifier is hardly affected by the intense lights, therefore, the noise figure could be kept low. The new double-pass system has achieved a flat-gain output at about 33.5 dB, which is 13.5 dB higher than that of the single-pass system with gain variation less than 1.3 dB at the flat-gain region. The noise figure varies from 5.9 to 6.6 dB in this region.     

Joint QoE-based user association and efficient cell–carrier distribution for enabling fully hybrid spectrum sharing approach in 5G mmWave cellular networks

Densifying the network by adding more minicell towers or relays throughout a hot spot area while extensively reusing the available spectrum is an essential choice to improve QoS. Unfortunately, this approach can be prohibitively costly. One possible solution to reduce the capital and operating expenditure in such overdensified networks is the adoption of the spectrum-sharing approach. However, both approaches would complicate the interference phenomenon either among inter- or intraoperators, which may cause serious performance degradation. In this paper, a fully hybrid spectrum-sharing (FHSS) approach aided by an efficient cell–carrier distribution was proposed with consideration to the interference dilemma. Moreover, an adaptive hybrid QoE-based mmWave user association (mUA) scheme was presented to assign a typical user to the serving mmWave base station (mBS), which offers the highest achievable data rate. The proposed FHSS approach (with the presented QoE-based mUA) was compared with recent works and with both FHSS approach using the conventional max-SINR-based mUA, which assigns a typical user to the tagged mBS carrying the highest signal-to-interference-plus noise ratio and the baseline scenario (licensed spectrum access). In particular, three spectrum access methods (licensed, semipooled, and fully pooled) were integrated in a hybrid manner to engage improved data rates to users. Numerical results show that the joint cell–carrier distribution and FHSS approach with QoE-based mUA outperform both baselines FHSS with the max-SINR mUA scheme and the licensed spectrum access. Furthermore, results demonstrate the effectiveness of the proposed approach in terms of both operators’ independence and fairness.

     

Multiobjective car relocation problem in one-way carsharing system

Railway Engineering Science - In this paper, we present a multiobjective approach for solving the one-way car relocation problem. We fix three objectives that include the number of remaining...     

Examination of Aschaffenburg and Drewry procedure for determination of Non-Casein-Proteins of milk by discontinuous polyacrylamide electrophoresis

Summary Non-casein protein fractions of raw skim med milk, obtained according to the Aschaffenburg and Drewry procedure, were studied by discontinuous polyacrylamide electrophoresis.Differences between the electropherograms obtained and the data of the above authors were observed in the fractions non-casein nitrogen minus proteose peptone nitrogen and total albumin nitrogen plus non-protein nitrogen.In the first fraction, instead of immunoglobulin, proteose-peptone was present and in the second fraction, besides the total albumin, immunglobulin and proteose-peptone were present. In our opinion the differences observed in the two fractions are due to incomplete salting out.

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Überprüfung der Aschaffenburg und Drewry-Bestimmungsmethode der Nicht-Casein-Proteine durch Polyacrylamid-Elektrophorese

Zusammenfassung Es wurden Nicht-Casein-Protein-Fraktionen von roher Magermilch, die nach der Aschaffenburg- und Drewry-Methode getrennt wurden, discelektrophoretisch untersucht. Unterschiede zwischen den erhaltenen Elektropherogrammen und den Angaben der oben genannten Autoren wurden bei den Fraktionen Nicht-Casein-Stickstoff minus Proteose-Pepton-Stickstoff und Totalalbumin-Stickstoff plus Nicht-Protein-Stickstoff festgestellt.Bei der ersten Fraktion wurde das Proteose-Pepton anstatt Immunglobulin erhalten, und bei der zweiten Fraktion erhielt man neben dem Totalalbumin auch Immunglobulin und Proteose-Pepton. Nach unserer Auffassung sind die bei den beiden Fraktionen festgestellten Abweichungen auf unvollständiges Aussalzen zurückzuführen.

     

Polymer electrolyte membrane modification in direct ethanol fuel cells: An update

Direct ethanol fuel cells (DEFCs) offer a high degree of design flexibility, ranging from a single cell to a massive multi-cell that can be used in various applications, including portable devices, transportation, and stationary applications. Unfortunately, the most significant barrier to the commercialization of DEFCs is getting low-cost and ethanol permeability, high conductivity performance, and extended durability of polymer electrolyte membranes, as key components that highly influence the overall performance. In this paper, the recent progress in developing the polymer electrolyte membrane for the application of DEFCs has been comprehensively reviewed. Focusing on an updated modification of polymeric materials in the last 5 years, including Nafion-based membrane, polyvinyl alcohol-based membrane, polybenzimidazoles-based membrane, chitosan-based membrane, and sodium alginate-based membrane, as well as factors and challenges that affected the performance of polymer electrolyte membranes have been discussed, including the main characterization, catalyst selection, cell design, and work in membrane and cell performance of DEFCs. All discussion addresses the strategy to improve the performance of polymer electrolyte membranes in DEFCs in order to penetrate the commercialization stages.     

COMPARISON AND VALIDATION OF OHM AND SCEM MEASUREMENTS FOR A FULL-SCALE COAL-FIRED POWER PLANT

Mercury emission measurements were performed at a 250 MW coal-fired power plant using the Ontario Hydro method (OHM) and semi-continuous emission monitors (SCEM). Flue gas sampling was performed at the inlet of the air preheater and at the outlet of the electrostatic precipitator. The results indicated that there is some agreement between the OHM and SCEM measurements on the total mercury species. However, the SCEM results were not always in good agreement with the OHM measurements on the elemental mercury species. These discrepancies in elemental mercury concentrations are probably the result of the differences in the location of the SCEM and OHM probes, the temperature difference between the SCEM sampling probe and the flue gas, and the nonuniformities in mercury concentration over the flue gas duct cross section. The other factor that contributed to the deviation between the SCEM and OHM measurement results is the sampling method: the SCEM measurements were performed at a single point while the OHM probe was traversed over multiple points over the duct cross section and the results were averaged. The effect of the SCEM sampling probe temperature was investigated by designing a sampling probe that could be heated to the sampled flue gas temperatures. This resulted in improvements in the accuracy of the elemental mercury measurements by the SCEM system.