Papers by Keyword: Resonance

Abstract: Paralleling SiC MOSFETs in high-power modules introduces overvoltage and oscillation risks due to parasitic capacitances and inductances. This study presents a 200 kW EV inverter module co-designed at the device and packaging level to ensure switching reliability under harsh automotive conditions. At 800 V, the planar SiC MOSFET maintained stable gate voltage, while a benchmark trench device module experienced severe ringing and failure. Kelvin-source structures and internal gate resistors mitigated parasitic turn-on, and device-level optimizations—including a 0.5 µm foundry technology, silicide gate, and hexagonal cell layout—improved body-diode performance, together with the channel mobility, blocking voltage, and minimized on-resistance and switching losses. The resulting AEPR25B12C1STJN module demonstrated effective resonance damping, matched the performance of commercial trench module FS03MR12A6MA1B in static and dynamic tests, and achieved 98% AC efficiency with over 200 kW output at 150 °C junction temperature.

Abstract: In 21st century, battlefields are being occupied by Artificial Intelligence (AI) controlled machines and one of its kind is mini-unmanned aerial vehicles. Upon arming the mini-UAVs, the load distribution and characterizing the vibrational behavior are important for its safe operation. Usually, the gun recoil force gets transferred to the platform of the mini-UAV, leading to instability or failure of the platform along with the gun. Mini-UAVs being too small don’t have the space to set the conventional recoil reduction mechanism. So, it is important to design a mechanism or alternative propellant for achieving the equivalent explosive force instead of TNT. Also, the influence of explosion on the vibration characteristics of the mini-UAV is studied. The high-pressure gas is found as the best alternative to TNT material, for reducing the deflection produced. This work primarily concentrates on determining the deflection and frequency induced in mini-UAVs. By using a pressure canister arrangement, the vibration characteristics under recoil can be improved.

Abstract: Anisotropy of a powder ferromagnetic product can be created by focusing separate particles in the direction of a certain crystallographic axis in a magnetic field. By fitting modes of electromagnetic field it is possible to regulate the intensity of clusters movement and powder particles, as well as to destroy clusters up to the separate particles. At the increase of constant magnetic field induction up to a certain value, typical for every material, the intensification of processes of secondary aggregation and formation of anisotropic layer structure takes place. A design model of magneto-vibrational state of finely divided powder suggested in the article enables to calculate the parameters of electromagnetic field, which provide optimal characteristics of a powder product. It has been shown that, at a certain ratio of parameters of electromagnetic field in a dispersive ferromagnetic medium, a chain system is formed. The chains are focused along magnetic-field lines and execute a vibration in a variable inhomogeneous magnetic field, according to the law of a string with fixed ends.

Abstract: La_0.8Sr_0.2MnO₃ was prepared to investigate the infrared emissivity of the sample under 0.76-2.5 μm and 2.5-500 μm infrared fields. The sample exhibited characteristic peaks of rhombohedral perovskite structure at 298-318 K, and split of the main peak weakened with increasing temperature. Intensity of the ferromagnetic resonance peak enhanced with increasing temperature, and the peak was shifted toward high magnetic field. A weak paramagnetic resonance peak appeared at 318 K, indicating that ferromagnetic-paramagnetic transition was occurring. The temperature of the sample under 2.5-500 μm field was higher than that under 0.76-2.5 μm. The emissivity of the sample increased with radiation time under 2.5-500 μm, but it had no obvious changes at about 0.665 under 0.76-2.5 μm. The emissivities at the same temperature fields were higher than those under 0.76-2.5 μm and 2.5-500 μm fields, respectively. It suggested that 0.76-2.5 μm and 2.5-500 μm radiations had inhibition effect on emissivity of La_0.8Sr_0.2MnO₃.

Abstract: The relationship of oscillations amplitude of the granular medium-elastic screw system whilst passing over resonance at different values of the bulk mass per unit length at different motion velocity has been studied. The relation of resonance oscillations of the granular medium-elastic screw system described by ratio α(t) and ν(t) has been shown. Based on these ratios, we plotted time variations of amplitude against quick passing over resonance.

Abstract: In the work the problem of complicating engineering structures and structures is raised, which in turn increases their vulnerability to natural phenomena. Each structure has some probability of destruction, an attempt to bring this probability to zero is accompanied by a rapid increase in its value. In addition, structures cannot be completely free from the risk of destruction due to uncertainties in the requirements for the system, the spread of the technical properties of building materials, the difficulties in adequately modeling the behavior of the system even with the use of modern software systems. The need to take into account the frequency composition of technogenic earthquakes which will allow to perform the necessary protection of structures that are particularly long-lasting from the resonance effect is considered and justified.

Abstract: The stress is made on the necessity to take into account the impact of higher while analysing the quality of voltage in power supply systems of coal mine. The process of resonances in power supply systems is explained in terms of physics, the sources generating this kind of interference are described. Mathematical dependences that allow to identify resonances in power supply systems are provided. The focus is placed on the feasibility of using spectral analysis in computations. To investigate the understudied aspects of voltage quality and electromagnetic compatibility and provide mathematical description for the analysis of resonances in electrical networks with powerful non-sinusoidal loads.

Abstract: This paper presents temperature sensitivity analysis of a silicon-polymer hybrid photonic micro-ring resonator. Photonic micro-ring resonators have hailed for their potential used in the next generation optical communications. However, like any other optical devices, temperature fluctuations alter the functionality of the micro-ring resonator. Hence, this paper provides a proposal for solution to minimize the temperature sensitive effect on the resonance characteristics. The temperature sensitivity effect of the pure silicon micro-ring resonaltor has been investigated. It is shown that the pure silicon micro-ring resonator is very sensitive to temperature. We added a negative thermo-optic polymer material with the positive thermo-optic silicon material to investigate the efeect of temperature sensitivity. Simulation tool Lumerical solution has been used to simulate the ring resonator. A polymer material of LFR is used to analyze the temperature effects. The hybrid composition of silicon-polymer were as 30%-70%, 40%-60%, 50%-50% and 60%-40% to investigate the temperature effect. The simulation was carried out using a ring size of 5 um, 10 um, 15 um and 20 um. The results show that the temperature insensitive ring resonator is possible with a 42% LFR polymer mixwd with 58% silicon.

Abstract: The dielectric elastomer minimum energy structure (DEMES) can realize large angular deformations by a small voltage-induced strain of the dielectric elastomer, so it is a suitable candidate to make a rotary joint for a soft robot. Driven with an alternating electric field, the joint deformation vibrational frequency follows the input voltage frequency. However, the authors find that if the rotational angel over a negative angle during dynamic response, the resonance mode will be different from the traditional, the vibration with the largest amplitude does not occur while the voltage frequency is equal to natural response frequency of the joint. Rather, the vibrational amplitude will be quite large over a range of other frequencies, at which the voltage frequency is greater than one time of the nature frequency and smaller than two times. This phenomenon was analyzed by relationship between the bending angle, applied voltage and bending moment of the film to the frame on a timeline. This new resonance mode can be applied to some biomimetic soft robots that consist of DEMES rotary joint.

Abstract: The weakening of the rock massive has been determined during boring of freezing tubes. It has been proved that the freezing column is disjoint from the massive by mud solution with strength 0,7-0,8 MPa, which fills out the drill hole Ø250mm. Were established lows of forming of the shear stress regions on the freezing pipe`s circuit. Were suggested adjunctive technological measures such as exhaust solution injection in the annular space, which reducing intensity of blasting loads on freezing pipe.