Probabilistic Monte-Carlo method for modelling and prediction of electronics component life

Power electronics are widely used in electric vehicles, railway locomotive and new generation aircrafts. Reliability of these components directly affect the reliability and performance of these vehicular platforms. In recent years, several research work about reliability, failure mode and aging analysis have been extensively carried out. There is a need for an efficient algorithm able to predict the life of power electronics component. In this paper, a probabilistic Monte-Carlo framework is developed and applied to predict remaining useful life of a component. Probability distributions are used to model the component’s degradation process. The modelling parameters are learned using Maximum Likelihood Estimation. The prognostic is carried out by the mean of simulation in this paper. Monte-Carlo simulation is used to propagate multiple possible degradation paths based on the current health state of the component. The remaining useful life and confident bounds are calculated by estimating mean, median and percentile descriptive statistics of the simulated degradation paths. Results from different probabilistic models are compared and their prognostic performances are evaluated

{(E)-2-Bromo-4-chloro-6-[3-(dimethyl­ammonio)propyl­imino­meth­yl]­phenol­ato}­dichloridozinc(II)

The title compound, [ZnCl2(C12H16BrClN2O)], is a mononuclear zinc(II) complex. The ZnII atom is four-coordinate in a tetra­hedral geometry, binding to the phenolate O and imine N atoms of the zwitterionic Schiff base ligand and to two Cl− ions. In the crystal structure, mol­ecules are linked through inter­molecular N—H⋯Cl hydrogen bonds to form chains running along the a axis

Ethyl 2-(4-nitro­phen­oxy)acetate

In the title mol­ecule, C10H11NO5, the methyl C atom deviates by 0.830 (6) Å from the mean plane of the remaining non-H atoms. In the crystal, weak C—H⋯O hydrogen bonds link the mol­ecules into layers parallel to the bc plane

Active Vibration Control of a Doubly Curved Composite Shell Stiffened by Beams Bonded with Discrete Macro Fibre Composite Sensor/Actuator Pairs

Doubly curved stiffened shells are essential parts of many large-scale engineering structures, such as aerospace, automotive and marine structures. Optimization of active vibration reduction has not been properly investigated for this important group of structures. This study develops a placement methodology for such structures under motion base and external force excitations to optimize the locations of discrete piezoelectric sensor/actuator pairs and feedback gain using genetic algorithms for active vibration control. In this study, fitness and objective functions are proposed based on the maximization of sensor output voltage to optimize the locations of discrete sensors collected with actuators to attenuate several vibrations modes. The optimal control feedback gain is determined then based on the minimization of the linear quadratic index. A doubly curved composite shell stiffened by beams and bonded with discrete piezoelectric sensor/actuator pairs is modeled in this paper by first-order shear deformation theory using finite element method and Hamilton’s principle. The proposed methodology is implemented first to investigate a cantilever composite shell to optimize four sensor/actuator pairs to attenuate the first six modes of vibration. The placement methodology is applied next to study a complex stiffened composite shell to optimize four sensor/actuator pairs to test the methodology effectiveness. The results of optimal sensor/actuator distribution are validated by convergence study in genetic algorithm program, ANSYS package and vibration reduction using optimal linear quadratic control scheme

New methodology for optimal placement of piezoelectric sensor/actuator pairs for active vibration control of flexible structures

This paper describes a computationally efficient method to determine optimal locations of sensor/actuator (s/a) pairs for active vibration reduction of a flexible structure. Previous studies have tackled this problem using heuristic optimization techniques achieved with numerous combinations of s/a locations and converging on a suboptimal or optimal solution after multithousands of generations. This is computationally expensive and directly proportional to the number of sensors, actuators, possible locations on structures, and the number of modes required to be suppressed (control variables). The current work takes a simplified approach of modeling a structure with sensors at all locations, subjecting it to external excitation force or structure base excitation in various modes of interest and noting the locations of n sensors giving the largest average percentage sensor effectiveness. The percentage sensor effectiveness is measured by dividing all sensor output voltage over the maximum for each mode using time and frequency domain analysis. The methodology was implemented for dynamically symmetric and asymmetric structures under external force and structure base excitations to find the optimal distribution based on time and frequency responses analysis. It was found that the optimized sensor locations agreed well with the published results for a cantilever plate, while with very much reduced computational effort and higher effectiveness. Furthermore, it was found that collocated s/a pairs placed in these locations offered very effective active vibration reduction for the structure considered

Fabrication and Characterization of Magnetic GQDs Using Green Tea Extract for Environmental Remediation

A graphene-based magnetic nanocomposite was synthesized and used as an effective adsorbent for crystal violet dye. The properties of the magnetic nanocomposite were characterized by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Vibrating Sample Magnetometer (VSM). This novel graphene-based magnetic nanocomposite showed great adsorptive ability towards the analytes and can easily separated from the water. When the amount of magnetic GQDs was 10 g/L, the removal rate of was more than 90%

Q-curvature Flow for GJMS Operators with Non-trivial Kernel

We investigate the prescribed Q-curvature flow for GJMS operators with non-trivial kernel on compact manifolds of even dimension. When the total Q-curvature is negative, we identify a conformally invariant condition on the nodal domains of functions in the kernel of the GJMS operator, allowing us to prove the global existence and the convergence of the flow to a metric which is conformal to the initial one, and having a prescribed Q-curvature. If the total Q-curvature is positive, we show that the flow blows up in finite time.Comment: 11 page