Optimization of Damping in a Semi-Active Car Suspension System with Various Locations of Masses

The key request for a vehicle suspension system is vibration control and decreasing the actual inertia forces. This ensures ride comfort for the crew and influences the fatigue level of the driver and overall driving safety. Implementing semi-active damping control in the vehicle suspension allows for adjusting the damping process in the vehicle for minimum acceleration applied to the seats, driver, and passengers. In order to implement theoretical analysis, we used a mathematical full-car model in Simulink/MATLAB. As the load, we added simulations of various artificially generated road profiles. The damping coefficient of the semi-active suspension system was optimized for maximum comfort level for a driver only. Results from the full-car simulation process deliver a graph of the output accelerations showing kinematic excitation from road deformities under various locations of vehicle load positions

Indirect Measurement of Electron Energy Relaxation Time at Room Temperature in Two-Dimensional Heterostructured Semiconductors

Hot carriers are a critical issue in modern photovoltaics and miniaturized electronics. We present a study of hot electron energy relaxation in different two-dimensional electron gas (2DEG) structures and compare the measured values with regard to the dimensionality of the semiconductor formations. Asymmetrically necked structures containing different types of AlGaAs/GaAs single quantum wells, GaAs/InGaAs layers, or bulk highly and lowly doped GaAs formations were investigated. The research was performed in the dark and under white light illumination at room temperature. Electron energy relaxation time was estimated using two models of I-V characteristics analysis applied to a structure with n-n+ junction and a model of voltage sensitivity dependence on microwave frequency. The best results were obtained using the latter model, showing that the electron energy relaxation time in a single quantum well structure (2DEG structure) is twice as long as that in the bulk semiconductor

Road Surface Profile Synthesis: Assessment of Suitability for Simulation

Vibration analysis plays an essential role to enhance the design of the vehicle, related to its comfort and safety level. It is useful to determine the relations between the road profile or its characteristics to the particular properties of vehicles and evaluate the dynamic response to the applied road profile. During the design stage, the simulation of vehicle suspension requires an input of road surface for the initial dynamic load. Therefore, an artificial road profile, created according to a specific methodology, is a key to overall research success. It is possible to generate an artificial road profile using several mathematical methods. This paper is dedicated to analyzing and comparing the usability and ISO-compatibility of three methods: White noise filtration, sinusoidal approximation, and moving average of white noise. Furthermore, we modified the sinusoidal approximation, additionally using a windowing function, thus removing sharp jumps in a generated road profile. Each analyzed method has its advantages and disadvantages, therefore, proper choice in profile generation was a goal of the provided analysis. We defined that the moving average of white noise filtration method has the highest implementation perspectives due to the best compliance to the desired ISO-defined road profile shape and independence from simulation velocity.This paper was supported by AutoDrive—“Advancing fail-aware, fail-safe, and failoperational electronic components, systems, and architectures for fully automated driving to make future mobility safer, affordable, and end-user acceptable” project, which has received funding from the European Union0 s Horizon 2020 research and innovation programme for 2014–2020, through the Electronic Component Systems for European Leadership (ECSEL) Joint Undertaking, under grant agreement no. 737469

Investigation of vibration spectrum ferroelectric semiconductor SbSBr nanowire

The temperature dependence of vibration spectra of one SbSBr chain (nanowire) in the direction of the c(z) – axis have been calculated in quasiharmonic approximation by diagonalization of dynamical matrix. The vibration frequencies in the direction of c(z) – axis have been derived by fitting of the experimental low – frequency ωs 2 of soft infrared (IR) mode of bulk – size SbSBr with theoretical quasiharmonic low - frequency ω2 of SbSBr nanowires. In this work the nature of anharmonism and temperature dependence of force constants between atoms in SbSBr crystal along c(z) – axis have been discussed. The anharmonism of all soft (at BZ k = 0) modes have been created by the interaction between phononsVytauto Didžiojo universitetasŠvietimo akademij

Theoretical Investigation of the Electronic Structure of Ferroelectric SbSBr Molecular Cluster

This paper presents the theoretical calculation of energy levels of the valence bands and bond orders of the SbSBr single crystals using the molecular cluster model consisting twenty SbSBr molecules. The theoretical calculation revealed that the ferroelectric phase transition changes the bond orders and shift valence bands. Results of theoretical calculations of averaged total density of states of SbSBr molecular cluster are compared with the experimentally results of X-ray photoelectron spectroscopy (XPS) of SbSI crystals, because that SbSI and SbSBr crystals have isomorphic electronic structureVilniaus universiteto Teorinės fizikos ir astronomijos institutasVytauto Didžiojo universitetasŠvietimo akademij

An Automotive Ferrofluidic Electromagnetic System for Energy Harvesting and Adaptive Damping

Vibration energy harvesting is receiving significant interest due to the possibility of using extra power in various machines and constructions. This paper presents an energy-harvesting system that has a structure similar to that of a linear generator but uses permanent magnets and magnetorheological fluid insets. The application of a standard vehicle example with low frequencies and amplitudes of the excitations was used for the optimization and experimental runs. The optimization for low excitation amplitudes shows that the best magnetic field change along the slider is obtained using differentially orientated radial magnets of 5 mm in width. This configuration was used for the experimental research, resulting in 1.2–3.28 W of power generated in the coils. The power conditioning system in the experimental research was replaced by loading resistors. Nevertheless, the initial idea of energy harvesting and a damping effect was confirmed by the circuit voltage output

Competition between Direct Detection Mechanisms in Planar Bow-Tie Microwave Diodes on the Base of InAlAs/InGaAs/InAlAs Heterostructures

The application of the unique properties of terahertz radiation is increasingly needed in sensors, especially in those operating at room temperature without an external bias voltage. Bow-tie microwave diodes on the base of InGaAs semiconductor structures meet these requirements. These diodes operate on the basis of free-carrier heating in microwave electric fields, which allows for the use of such sensors in millimeter- and submillimeter-wavelength ranges. However, there still exists some uncertainty concerning the origin of the voltage detected across these diodes. This work provides a more detailed analysis of the detection mechanisms in InAlAs/InGaAs selectively doped bow-tie-shaped semiconductor structures. The influence of the InAs inserts in the InGaAs layer is investigated under various illumination and temperature conditions. A study of the voltage–power characteristics, the voltage sensitivity dependence on frequency in the Ka range, temperature dependence of the detected voltage and its relaxation characteristics lead to the conclusion that a photo-gradient electromotive force arises in bow-tie diodes under simultaneous light illumination and microwave radiation