Formulation of a MIMO linear power system stabiliser for identical generating units at a common busbar

The fundamental formulation, analysis and sample simulation studies reported show how the linear power system stabiliser (PSS) can be evolved so as to accommodate more than one identical power generating unit operating at a common busbar. The presentation augments the more conventional approach by which the PSS is formulated for a single-machine-infinite-busbar system. In preference to single-generator installations, practical generating stations frequently configure multiple identical units to operate in parallel. Although this reduces dependence on a single unit, a multi-unit configuration is susceptible to oscillations between two or more units. Such oscillations are classified as intraplant dynamics. The proposed PSS formulation includes rigorous consideration of intraplant dynamics at the design stage. Simulation studies clearly substantiate the superiority of the proposed multi-input-multi-output PSS over the more conventional single-input-single-output version.     

Low frequency oscillations in power systems: A physical account and adaptive stabilizers

This paper presents a physical explanation of the phenomenon of low frequency oscillations experienced in power systems. A brief account of the present practice of providing fixed gain power system stabilizers (PSS) is followed by a summary of some of the recent design proposals for adaptive PSS. A novel PSS based on the effort of cancelling the negative damping torque produced by the automatic voltage regulator (AVR) is presented along with some recent studies on a multimachine system using a frequency identification technique.     

Improved Dual-Polarity Response via Pyro-phototronic Effect for Filterless Visible Light Communication

Dual-polarity response photodetectors (PDs) take full advantage of the directivity of the photocurrent to identify optical information. The dual-polarity signal ratio, a key parameter that represents the equilibrium degree of responses to different lights, is proposed for the first time. The synchronous enhancement of dual-polarity photocurrents and the amelioration of the dual-polarity signal ratio are beneficial to the practical applications. Herein, based on the selective light absorption and energy band structure design, a self-powered CdS/PEDOT:PSS/Au heterojunction PD consisting of a p-n junction and a Schottky junction exhibits unique wavelength-dependent dual-polarity response, where the photocurrent is negative and positive in the short and long wavelength regions, respectively. More importantly, the pyro-phototronic effect inside the CdS layer significantly improves the dual-polarity photocurrents with the maximum enhancement factors of 120%, 343%, 1167%, 1577%, and 1896% at 405, 450, 532, 650, and 808 nm, respectively. Furthermore, the dual-polarity signal ratio tends to 1:1 due to different degrees of the enhancement. This work provides a novel design strategy for dual-polarity response PDs with a simple working principle and improved performance, which can supply a substitution for two traditional PDs in the filterless visible light communication (VLC) system.     

On the high-frequency instability of plasma in the octupole galathea electric discharge trap

Spectra of microwave plasma oscillations in an electric discharge trap are considered, and specific features of these spectra related to the instability of transverse current near the magnetic barrier confining the plasma are revealed. A relation between oscillations of the discharge current and the modulation of intensity of the microwave oscillations is established which indicates that the barrier region of discharge possesses an anomalous resistivity.     

Spectra of microwave oscillations in an SPD-ATON stationary plasma thruster

The spectra of microwave oscillations and electromagnetic radiation in an SPD-ATON stationary plasma thruster have been measured. Using the results of determination of the spectral characteristics and the spatial distribution of microwave intensity, features of the plasma jet instability manifestations related to the trapping of electrons in a magnetic field of the acceleration channel are analyzed. A method for the evaluation of the spectral and energy parameters of microwave oscillations and electromagnetic radiation generated by the operating plasma thruster is proposed.     

An approach for the modelling and quantification of PSS customisation

A Product–Service System (PSS) is a dynamic and multidimensional system that is comprised of products, services, a large network of stakeholders and all necessary supporting infrastructures, aiming towards becoming continuously competitive, satisfying customer needs and improving environmental aspects. The design of such a system and its evaluation throughout the lifecycle are challenging tasks owing to their inherent complexity, which becomes even greater when the aspect of customisation is considered. Nevertheless, the literature work regarding the customisation of PSS is scarce. Towards bridging this gap, the present work proposes a framework for PSS customisation, including the main steps that are required for a successful PSS customisation. For each step in the framework, which has been collected from the literature, PSS approaches have been provided, and could be used in the execution of each step. Next, the present study introduces a method for: (i) the modular representation of PSS based on vector analysis, and then (ii) the quantification of the PSS customisation degree.     

The effect of phase stabilization of microwave oscillations in nanosecond Gunn oscillators

The effect of the semiconductor structure of an oscillator diode on the phase stabilization of microwave oscillations in a nanosecond Gunn oscillator by using a modulating voltage pulse edge is investigated. Numerical simulation is employed to determine phase deviations depending on the scatter of pulseedge duration and pulse amplitude. The standard deviation of phase-delay time of microwave oscillations in the oscillator with regard to a constant level at the modulating pulse edge and the standard deviation of phase difference of microwave oscillations in two electrodynamically insulated oscillators connected in parallel to one and the same modulator have been measured.     

Instability of decelerating electron flow injected into a planar diode

The instability of a decelerating electron flow injected into a planar diode has been studied using the results of experiments and the exact solution of a system of inhomogeneous hydrodynamic equations formulated in the first-order approximation of the theory of stability. A dispersion equation is obtained that relates the frequencies and increments (decrements) of the arising electromagnetic oscillations to the electron flux parameters and the diode characteristics. A solution of this dispersion equation shows that a diode, in which the decelerating electron flow is propagating, features a previously undescribed instability of oscillations in the microwave range. This instability takes place in cases where no potential minimum is formed in the diode in a stationary state. The development of the instability of oscillations with theoretically predicted frequencies and increments has been confirmed in experiments.     

Synchronization of spin-transfer nanooscillator using phase-locking loop

It is suggested to use the phase locking (PL) principle for solving problems of synchronization and coherent power addition for spin-transfer microwave nanooscillators employing the phenomenon of magnetization oscillations in the microwave range excited by a spin-polarized current. The dynamics of a model spin-transfer oscillator with an inertial PL loop is considered. The regions of parameters corresponding to various dynamic regimes (synchronous, quasi- synchronous, beats) have been determined using bifurcation analysis. It is shown that the band of existence of synchronous regimes for a spin-transfer nanooscillator with a PL loop increases as compared to the analogous system synchronized by an external field.     

Experimental study of the effect of external signal on microwave oscillations in a nonrelativistic electron beam with virtual cathode

The effect of an external harmonic signal on the characteristics of microwave generation in a non-relativistic electron beam with virtual cathode (VC) formed in a static retarding electric field (low-voltage vircator system) has been experimentally studied. A significant increase in the vircator generation power is observed when the frequency of the external signal is close to the frequency of VC oscillations. At large detunings, a broadband chaotic generation is observed.     

Resonance RF emission from water

The method and results of an experimental investigation of stable intrinsic RF (microwave) emission from water upon EHF 65 GHz → UHF 1 GHz resonance excitation are described. The Curie point for the radiation quenching is determined at 95°C. The mechanism of emission is explained in terms of conservation of the synchronization and polarization of the superthermal selective oscillations in the molecular system of water, which are induced by a short-term resonance action of linearly polarized EHF radio waves of low intensity.     

Microwave oscillations in the acceleration channel of SPD-ATON stationary plasma thruster

The parameters of microwave plasma oscillations in the acceleration channel of an SPD-ATON stationary plasma thruster have been measured. There is a stable correlation between the microwave intensity, on the one hand, and the magnetic field configuration in the region of plasma acceleration and the formation of plasma flow detached from the channel wall, on the other hand. The experimental data agree with the notion about the contribution of the electron scattering on microwave oscillations to the anomalous transverse conductivity of plasma in the acceleration channel.     

Generator of chaotic microwave oscillations based on a high-power bipolar transistor

A chaotic microwave autooscillatory system has been designed, implemented on a high-power bipolar transistor (2T 982 A-2), and studied. The experiments showed stable generation of chaotic oscillations in a 5.26?C5.44 GHz range with a spectral power density of 1.3 × 10^?3 W/MHz.     

Stationary regimes of the turbulent plasma acceleration in a high-current magnetoplasmadynamic thruster

A reliable relationship is established between the electric propulsion parameters of a high-current magnetoplasmadynamic thruster and the intensity of both microwave radiation and low-frequency oscillations in the system. It is shown that realization of the stationary regimes of the turbulent plasma acceleration is limited by the excitation of a large-scale ion-sound turbulence in the plasma flow.     

PSS resin-fortified polythiophene nanoparticles for highly transparent conducting films

Polythiophene/poly(sodium 4-styrene sulfonate) (PT/PSS) composite nanoparticles having different particle size were prepared by Fe(3+)-catalyzed oxidative polymerization in aqueous medium. This facile method includes a FeCl3/H2O2 (catalyst/oxidant) combination system, which guarantees a high conversion (more than 95%) of thiophene monomers in various concentration of poly(styrene sulfonate) (PSS) with only a trace of FeCl3. Particle size of PT/PSS composite nanoparticles decreased from 134 nm to 26 nm as the concentration of PSS and H2O2 increased, and which was confirmed by SEM and CHDF analyses. The poly(ethylene terephthalate) (PET) film coated with PT/PSS was transparent and showed a high conductivity in a dried state. The sheet resistivity decreased as the ratio of PT to PSS increased. Photoluminescence property of the PT/PSS composite nanoparticles was also investigated.     

可持续背景下产品服务系统设计框架研究

目的在可持续背景下研究产品服务系统的设计方法,提出整合产品和服务进行产品服务系统设计的设计框架。方法分析产品服务系统的基本属性和特征,结合可持续发展的具体要求,论述产品服务系统设计方法研究的重要性,进而分析当前产品服务系统设计方法的相关研究成果,提出从设计学科角度系统审视产品服务系统的设计过程和方法的观点。结论从设计师角度可将产品服务系统设计程序划分为6个阶段,并按照产品服务系统设计中信息流的逻辑关系组织起来,建立产品服务系统设计框架。     

Generating dynamic microwave chaos in self-oscillating ring system based on complementary metal-oxide-semiconductor structure

We have designed, implemented, and studied a chaotic self-oscillating system based on a monolithic integrated circuit on a silicon substrate. Experimental prototypes demonstrated stable generation of chaotic microwave oscillations with a maximum spectral power density in a frequency range of 2.8–3.8 GHz.     

Tunable generator of broadband chaotic microwave oscillations on turbulent electron beams

A new generator of broadband chaotic microwave oscillations of medium power on turbulent electron beams is proposed, in which it is possible to tune the generation regime. The characteristics of turbulent electron beams have been studied by experimental and theoretical methods. It is established that drag of the electron beam produces its turbulization, which leads to the generation of broadband chaotic microwave oscillations.     

Relativistic magnetron with distributed output of microwave radiation

Problems related to the extraction and shaping of microwave radiation generated by a relativistic magnetron have been experimentally studied. A modified magnetron oscillator is described, in which a coupling waveguide channel loaded on a system of radiators is provided between elements of the resonance system. It is shown that this scheme allows the required amplitude-phase profiles of oscillations to be obtained and ensures high spectral and amplitude stability of the output radiation.     

Small-size ultralow-voltage generator of chaotic microwave oscillations

The scheme of a small-size ultralow-voltage generator of broadband chaotic microwave oscillations is considered. Results of numerical modeling and experimental investigation of the device prototype operating in various regimes are summarized. Good prospects of the proposed ultralow-voltage generator (vircator) are related to the relatively low accelerating voltages (below 1000 V), rather high electron beam currents (up to 800 mA), good efficiency (up to 5%), and small dimensions of the device.