Goal The purpose of the article is to further develop analytical methods for calculating and synthesizing power electronics systems with deep pulse width modulation (PWM). A three-circuit linear ...electric drive system for positioning the working body of the mechanism of onboard aircraft equipment, in which the linear electric motor is controlled from a pulse width converter (PWC), is considered. The power converter is included in the current loop. It has a noticeable effect on the level of current ripple, travel speed and positioning accuracy of the operating mechanism of a linear electric drive. Methodology. To analyze the processes in the current loop, a discrete transfer function of a pulse-width converter for PWM in the final zone and «in the large» is obtained on the basis of the statistical linearization of the modulation characteristics of the multi-loop PWM model. The modulation characteristic of each circuit of the model is obtained as a result of the Fourier series expansion in Walsh functions of the output voltage of the PWM during the PWM process. Statistical linearization of modulation characteristics is performed based on Hermite polynomials. Results. During the analysis, discrete transfer functions of closed current loops, velocity and open loop position were obtained, for which a digital controller was synthesized in the form of a recursive filter. Originality. The parameters of the regulator links are found, which make it possible to complete the transient process in four PWC switching periods with an overshoot of no more than 6 %. The analysis of the speed-optimized positioning process of a linear electric drive based on the LED AT 605TU motor is carried out. Practical significance. The purpose of the analysis was to establish the relationship between the switching period of the PWM and the value of the uncompensated constant, at which the pulsations of the positioning process are minimal while ensuring the minimum overshoot and maximum speed. It was found that the specified requirements are satisfied by the ratio between the switching period, PWC and uncompensated constant in the range of one or two.
The issue of distribution of large amounts of information on server stations is researched. The analysis of existing methods for distributing data of heavily loaded web applications is carried out. A ...system for computing load distribution using a balancing server is proposed. A description of the software necessary for the functioning of the system and server management interface is provided.
We analyze the benefits and shortcomings of a thermal control in nanoscale electronic conductors by means of the contact heating scheme. Ideally, this straightforward approach allows one to apply a ...known thermal bias across nanostructures directly through metallic leads, avoiding conventional substrate intermediation. We show, by using the average noise thermometry and local noise sensing technique in InAs nanowire-based devices, that a nanoscale metallic constriction on a SiO2 substrate acts like a diffusive conductor with negligible electron-phonon relaxation and non-ideal leads. The non-universal impact of the leads on the achieved thermal bias-which depends on their dimensions, shape and material composition-is hard to minimize, but is possible to accurately calibrate in a properly designed nano-device. Our results allow to reduce the issue of the thermal bias calibration to the knowledge of the heater resistance and pave the way for accurate thermoelectric or similar measurements at the nanoscale.
Stealth coating is the antidote against of the radar. But it can be disclosed by the microwave radiometer because their job based on the measuring the radio-brightness contrast between Stealth object ...and the background of the environments (sky is cold, Earth is warm). This short report presents some math model for the simplest calculation of the possible disclosing distance till the Stealth object.
Silicon can be isotopically enriched, allowing for the fabrication of highly coherent semiconductor spin qubits. However, the conduction band of bulk Si exhibits a six-fold valley degeneracy which ...may adversely impact the performance of silicon quantum devices. To date, the spatial characterization of valley states in Si has remained limited. Moreover, techniques for probing valley states in functional electronic devices are needed. Here, we describe a cryogen-free scanning gate microscope for the characterization of Si/Si0.7Ge0.3 quantum devices at mK temperatures. The newly built instrument is the first cryogen-free scanning gate microscope capable of forming and measuring a quantum dot on a Si/SiGe device with an overlapping gate structure without compromising the ability to host multiple DC and microwave lines for quantum control experiments. The microscope is based on the Pan-walker design, with coarse positioning piezostacks and a fine scanning piezotube. A tungsten microscope tip is attached to a tuning fork for active control of the tip-to-sample distance. To reduce vibration noise from the pulse tube cooler, we utilize both active and passive vibration isolation mechanisms and achieve a root-mean-square noise in z of ∼2 nm. Our microscope is designed to characterize fully functioning Si/Si0.7Ge0.3 quantum devices. As a proof of concept, we use the microscope to manipulate the charge occupation of a Si quantum dot, opening up a range of possibilities for the exploration of quantum devices and materials.
We present the development and testing of a Micromegas detector prototype and its front end intended to be a candidate for the substitutions of some of the Multiwire Proportional Chambers in the ...future AMBER (NA66) experiment at CERN. Results of the test of the first small size prototype are discussed.
•The Apparatus for Mesons and Baryon Experimental Research at CERN is requiring new detectors.•Micro-Pattern Gaseous Detector technology is a good candidate for the future upgrades.•MICRO-MEsh GAS detector read-out by the Torino Integrated Gem Electronics for Read-out ASIC.
The present contribution reviews the principle of RF separation and explains its dependence on different parameters of beam optics and hardware. The first examination of potential showstoppers for ...the RF-separated beam implementation for Phase-2 of the AMBER experiment in the M2 beam line of the North Area is presented. Different beam optics settings have been examined, providing either focused or parallel beams inside the RF cavities. The separation and transmission capability of the different optics settings for realistic characteristics of RF cavities are discussed and the preliminary results of the potential purity and intensity of the RF-separated beam are presented. These show that a trade-off between the overall beam intensity and the share of the required particle type in the overall beam needs to be established. No showstoppers have been identified for achieving the beam parameters required for AMBER’s kaonic Primakoff reactions, kaon spectroscopy, prompt-photon production and kaon charge-radius programs. However, the high beam intensity requirements of the AMBER Drell–Yan programme cannot be satisfied with an RF-separated beam.
Abstract
The article deals with optimization issues in design of an automatic control system (ACS). The method of multicriteria optimization is presented, which combines simulation of ACS and ...optimization procedure based on a genetic algorithm and implemented by the MATLAB / Global Optimization Toolbox. The method of the generalized criterion composition based on the initial particular criteria is also proposed. The use of this generalized criterion makes it possible to reduce the complexity of determining the optimal parameters of the ACS and allows to take into account the constraints when searching for the optimal solution.
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