A new hybrid implicit-explicit FDTD method for local subgridding in multiscale 2-D TE scattering problems

The conventional finite-difference time-domain (FDTD) method with staggered Yee scheme does not easily allow including thin material layers, especially so if these layers are highly conductive. This paper proposes a novel subgridding technique for 2-D problems, based on a hybrid implicit-explicit scheme, which efficiently copes with this problem. In the subgrid, the new method collocates field components such that the thin layer boundaries are defined unambiguously. Moreover, aspect ratios of more than a million do not impair the stability of the method and allow for very accurate predictions of the skin effect. The new method retains the Courant limit of the coarse Yee grid and is easily incorporated into existing FDTD codes. A number of illustrative examples, including scattering by a metal grating, demonstrate the accuracy and stability of the new method

Statistical Power Supply Dynamic Noise Prediction in Hierarchical Power Grid and Package Networks

One of the most crucial high performance systems-on-chip design challenge is to front their power supply noise sufferance due to high frequencies, huge number of functional blocks and technology scaling down. Marking a difference from traditional post physical-design static voltage drop analysis, /a priori dynamic voltage drop/evaluation is the focus of this work. It takes into account transient currents and on-chip and package /RLC/ parasitics while exploring the power grid design solution space: Design countermeasures can be thus early defined and long post physical-design verification cycles can be shortened. As shown by an extensive set of results, a carefully extracted and modular grid library assures realistic evaluation of parasitics impact on noise and facilitates the power network construction; furthermore statistical analysis guarantees a correct current envelope evaluation and Spice simulations endorse reliable result

High performance computing of explicit schemes for electrofusion jointing process based on message-passing paradigm

The research focused on heterogeneous cluster workstations comprising of a number of CPUs in single and shared architecture platform. The problem statements under consideration involved one dimensional parabolic equations. The thermal process of electrofusion jointing was also discussed. Numerical schemes of explicit type such as AGE, Brian, and Charlies Methods were employed. The parallelization of these methods were based on the domain decomposition technique. Some parallel performance measurement for these methods were also addressed. Temperature profile of the one dimensional radial model of the electrofusion process were also given

Modelling and simulation of voltage source converter with different control technique for offshore windfarm application

The uses of Voltage Source Converter is not something new in wind farm power generation. Advance technologies in rebuilding VSC that can control the output of alternating current (AC) through several current control technique produces from the wind energy, sometime lead to distortion that can disturb another component whether in VSC itself or effecting another equipment. In wind farm power generation, power VSC commonly used in order to deal with large value of voltage and current produced from wind energy. Hence, more electronic device and components will be used to deal with this situation. This is to some extent will create disturbances to the system that will not be seen through human naked eye. Through this paper, a conventional current control method, that is linear PWM is present. This method is much more complicated compare to proposed method, that is predictive current control. The function of multi predictive control (MPC) in determining the future value for the feedback signal into inverter is explained in 4.3. The result of this two method is analyse in aspect of total harmonic distortion (THD) for both voltage and current during transient state and steady state. During transient state for current, both of the methods exceed the IEEE-519 standards. Hence it is recommend to install several equipments to protect the facility of windfarm itself. While for steady state, both of the methods succeed maintain the THD below 5% for voltage and current

High-speed extended-term time-domain simulation for online cascading analysis of power systemalysis of Power System

A high-speed extended-term (HSET) time domain simulator (TDS), intended to become a part of an energy management system (EMS), has been newly developed for use in online extended-term dynamic cascading analysis of power systems. HSET-TDS includes the following attributes for providing situational awareness of high-consequence events: i) online analysis, including n-1 and n-k events, ii) ability to simulate both fast and slow dynamics for 1-3 hours in advance, iii) inclusion of rigorous protection-system modeling, iv) intelligence for corrective action ID, storage, and fast retrieval, and v) high-speed execution. Very fast on-line computational capability is the most desired attribute of this simulator. Based on the process of solving algebraic differential equations describing the dynamics of power system, HSET-TDS seeks to develop computational efficiency at each of the following hierarchical levels, i) hardware, ii) strategies, iii) integration methods, iv) nonlinear solvers, and v) linear solver libraries. This thesis first describes the Hammer-Hollingsworth 4 (HH4) implicit integration method. Like the trapezoidal rule, HH4 is symmetrically A-Stable but it possesses greater high-order precision (h4) than the trapezoidal rule. Such precision enables larger integration steps and therefore improves simulation efficiency for variable step size implementations. This thesis provides the underlying theory on which we advocate use of HH4 over other numerical integration methods for power system time-domain simulation. Second, motivated by the need to perform high speed extended-term time domain simulation (HSET-TDS) for on-line purposes, this thesis presents principles for designing numerical solvers of differential algebraic systems associated with power system time-domain simulation, including DAE construction strategies (Direct Solution Method), integration methods(HH4), nonlinear solvers(Very Dishonest Newton), and linear solvers(SuperLU). We have implemented a design appropriate for HSET-TDS, and we compare it to various solvers, including the commercial grade PSS\E program, with respect to computational efficiency and accuracy, using as examples the New England 39 bus system, the expanded 8775 bus system, and PJM 13029 buses system. Third, we have explored a stiffness-decoupling method, intended to be part of parallel design of time domain simulation software for super computers. The stiffness-decoupling method is able to combine the advantages of implicit methods (A-stability) and explicit method(less computation). With the new stiffness detection method proposed herein, the stiffness can be captured. The expanded 975 buses system is used to test simulation efficiency. Finally, several parallel strategies for super computer deployment to simulate power system dynamics are proposed and compared. Design A partitions the task via scale with the stiffness decoupling method, waveform relaxation, and parallel linear solver. Design B partitions the task via the time axis using a highly precise integration method, the Kuntzmann-Butcher Method - order 8 (KB8). The strategy of partitioning events is designed to partition the whole simulation via the time axis through a simulated sequence of cascading events. For all strategies proposed, a strategy of partitioning cascading events is recommended, since the sub-tasks for each processor are totally independent, and therefore minimum communication time is needed

Production of herbal shampoo from Madagascar periwinkle

Recently, the society interest in using herbal shampoos has increased significantly. Big companies have started to produce herbal shampoo to meet the market demands. However, most of these shampoos contain chemicals that could be harmful to human health. The main purpose of this study are to produce homemade herbal shampoo from Madagascar Periwinkle plant without harmful chemicals and have additional benefits to consumers. By using stem and leaf extract from the plant and cold press machine, we analysed the quantitative aspect of the extracts and use it as a main ingredient to produce homemade herbal shampoo. The extracts are then used as ingredients in production of the shampoo. Several tests were conducted to determine the performance of the shampoos. The Fourier Transform Infrared Spectroscopy (FTIR) analysis shows presence oh -OH groups and C=O bond to indicate the presence of vinca alkaloids. The performance tests result inconsistent to one extract only. This study provided an information to future researchers regarding the study of Madagascar Periwinkle and effectiveness of this plant in herbal shampoos production

Transient Analysis of Power Distribution Networks and Transmission Lines Using the Latency Insertion Method

As semiconductor devices become more densely integrated on a single chip, complexity of packaging has also increased accordingly, which induces signal integrity and power integrity (SI/PI) issues. In order to efficiently capture the behavior of interconnects and address the SI/PI problems, fast and accurate modeling is required. Past research investigated a fast transient simulation algorithm called the Latency Insertion Method (LIM) and, based on its developed a novel circuit simulator called Alternating Direction Explicit LIM (ADE-LIM). This thesis reports on the simulation of circuit models for different structures including transmission lines and power distribution networks (PDNs), using LIM and ADE-LIM to have been simulated using the simulator to study multiple SI/PI problems. In addition, Monte Carlo simulation has been investigated to study the effect of random variation of circuit parameter on signal output.Ope

STUDY ON-CHIP METAL-INSULATOR-SEMICONDUCTOR-METAL INTERCONNECTS WITH THE ALTERNATING-DIRECTION-IMPLICIT FINITE-DIFFERENCE TIME-DOMAIN METHOD

The Alternating-Direction-Implicit Finite-Difference Time-Domain method is used to analyze the on-chip Metal-Insulator-Semiconductor-Metal interconnects by solving Maxwell's equations in time domain. This method is efficient in solving problems with fine geometries much smaller than the shortest wavelength of interest. The iteration algorithm is evaluated thoroughly with respects to stability, numerical dispersion, grid size, time-step size etc.. The dielectric quasi-TEM mode, the slow wave mode, and the skin-effect mode of the MISM structure are all analyzed. We find that semiconductors can readily operate from the slow wave mode, to the transition region, to the skin effect mode in state of art technology. This thesis shows that the silicon substrate losses and the metal line losses can be modeled with high resolution. Signal dispersion and attenuation over a wide range of doping densities and operating frequencies is discussed. Accurate prediction of interconnect losses is critical for high-frequency design with highly constrained timing requirements