Application of quasi-Newton method to load flow studies and solution of load flow during three-phase fault

Newton's method, because of its quadratic convergence, is mathematically the most preferable of the several known methods for the solution of load flow problems. However, this method is not absolutely convergent for ill-conditioned problems. This paper presents a modification to Newton's method designed to reduce the number of function evaluations required in the solution of the load flow problem. It is a variation of Newton's method, in which the partial derivatives are replaced by difference equations, which is capable of giving significant improvement for routine load flow studies.In addition, an algorithm using the Freudenstein-Roth technique is incorporated in the program. This technique, which is essentially a parameter perturbation procedure, together with the quasi-Newton method, envisages a fast and accurate solution for load flow during a solid three-phase short-circuit.     

Steady state analysis of power systems including the effects of control devices

A new power flow model based on a power-perturbation technique has been developed for the steady state analysis of large complex power systems. The model includes the complex load representation and control characteristics of various generators; it also incorporates the effect of automatic load-frequency control, load shedding, generation shedding and on-line tap-changing transformers. When a power system is dynamically stable following a major disturbance, the system will be in an alert on an emergency state, having an energy imbalance. In the proposed technique this imbalance is compensated for according to the steady state characteristics of the control devices and load or generation shedding. The load shedding is activated on the basis of frequency deviation, voltage limits, and line ratings. Thus, the new method allows the study of the power flow under abnormal conditions as well as normal conditions. The major advantage of the procedure is its inherent simplicity and rapid convergence behaviour, resulting in a quick post-transient load flow solution in a quasidynamic manner. The feasibility of the technique is demonstrated by numerical examples and results of cases run on the American Electric Power Systems are included.     

Properties of linear switching time-varying discrete-time systems with applications

We study two discrete-time, linear switching time-varying (LSTV) structures, each of which consists of a periodic switch connected to several linear time-invariant (LTI) systems. Such structures can be used to represent any linear periodically time-varying (LPTV) systems. We give basic properties associated with the LSTV structures in terms of their LTI building blocks, and then apply the results to solve a general approximation problem: How to optimally approximate an LPTV system with period p by an LPTV system with period ? The optimality is measured using norms. The study is extended to general multirate periodic systems.     

Feasibility Improved Stochastic Dynamic Programming for Optimization of Reservoir Operation

Water Resources Management - Stochastic Dynamic Programming (SDP) is a major method for optimizing reservoir operation. Handling non-linear, non-convex and non-differentiable objective functions...     

Robust weighted H∞ filtering for networked systems with intermittent measurements of multiple sensors

In this paper, we investigate the robust weighted H_∞ filtering problem for networked systems with intermittent measurements under the discrete‐time framework. Multiple outputs of the plant are measured by separate sensors, each of which has a specific failure rate. Network‐induced delay, packet dropouts and network‐induced disorder phenomena are all incorporated in the modeling of the network link. The resulting closed‐loop system involves both delayed noise and non‐delayed noise. In order to make full use of the delayed information, we define a weighted H_∞ performance index. Sufficient delay‐dependent and parameter‐dependent conditions for the existence of the filter and the solvability of the addressed problem are given via a set of linear matrix inequalities. Two simulation examples are presented to illustrate the relationship between the minimal performance level and the weighting factor, which show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.     

DESIGN OF A SENSITIVE MEMBRANE OPTODE FOR IRON DETERMINATION

An optical chemical sensor has been developed for the sensitive determination of Fe (III) ions by spectrophotometry. The optical membrane was constructed by immobilization of methyltrioctylammonium chloride on triacetylcellulose polymer. The exchange of thiocyanate as counter ion in the membrane sensitized this film to Fe (III). The sensing membrane is capable of determining Fe(III) reversibly over a dynamic range of 7.11 × 10^?7?8.88 × 10^?5 mol L^?1 with a limit of detection of 6.02 × 10^?7 mol L^?1 and a response time of 5 min. This optode can easily be regenerated by 0.1 mol L^?1 of sodium fluoride solution. The relative standard deviation for eight replicate measurements of 7.11 × 10^?6 and 5.33 × 10^?5 mol L^?1 of Fe (III) was 4.2 and 3.7%, respectively. The sensor was successfully applied for the determination of iron in tablet and water samples.     

Optimal design of nonuniform multirate filter banks

The design of general nonuniform filter banks is studied. Contrary to uniform filter banks, in nonuniform filter banks, it may not be possible to achieve perfect reconstruction, but in some cases by using optimization techniques, we can design acceptable filter banks. Here, the initial finite impulse response (FIR) analysis filters are designed according to the characteristics of the input. By the design procedure, the FIR synthesis filters are found so that theH-norm of an error system is minimized over all synthesis filters that have a prespecified order. Then, the synthesis filters obtained in the previous step are fixed, and the analysis filters are found similarly. By iteration, theH-norm of the error system decreases until it converges to its final value. At each iteration, the coefficients of the analysis or synthesis filters are obtained by finding the least squares solution of a system of linear equations. If necessary, the frequency characteristics of the filters can be altered by adding penalty terms to the objective function.This research was supported by the Natural Sciences and Engineering Research Council of Canada.     

In vitro and in vivo evaluation of paclitaxel–lapatinib-loaded F127 pluronic micelles

The aim of this study was to evaluate the in vitro and in vivo efficacy of paclitaxel–lapatinib-loaded Pluronic micelles. Lapatinib and pluronic sensitize the cancerous cells to paclitaxel via efflux pump inhibition. In addition, pluronic polymers can trigger intrinsic apoptosis pathways. Furthermore, micellar system can passively target the chemotherapeutic agents by enhanced permeability and retention effect. The paclitaxel–lapatinib-loaded micelles were characterized in means of encapsulation efficacy and size. The in vitro analyses were performed by MTT assay and uptake studies. Real-time imaging and in vivo anti-tumor efficacy studies were also performed. The prepared micelles have acceptable encapsulation ratio and size. Hemolysis assay confirmed that the micelles are hemo-compatible. MTT assay demonstrated that drug-loaded micelles have superior cytotoxicity compared with the naked drugs. The confocal microscopy and flowcytometry analyses showed that micelles are mainly internalized by endocytosis. According to the results of the in vivo imaging, the micelles are accumulated within liver. In vivo anti-tumor efficacy studies confirmed that tumor inhibition of drug-loaded micelles was significant compared to Intaxel^®.     

A nonlocal computational homogenization of softening quasi-brittle materials

In this paper, a computational counterpart of the experimental investigation is presented based on a nonlocal computational homogenization technique for extracting damage model parameters in quasi-brittle materials with softening behavior. The technique is illustrated by introducing the macroscopic nonlocal strain to eliminate the mesh sensitivity in the macroscale level as well as the size dependence of the representative volume element (RVE) in the first-order continuous homogenization. The macroscopic nonlocal strains are computed at each direction, and both the local and nonlocal strains are transferred to the microscale level. Two RVEs with similar geometries and material properties are introduced for each macroscopic Gauss point, in which the microscopic damage variables and the macroscale consistent tangent modulus and its derivatives are obtained by imposing the macroscopic nonlocal strain on the first RVE, and the macroscopic stress is computed by employing the microscopic damage variables and imposing the macroscopic local strain over the second RVE. Finally, numerical examples are solved to illustrate the performance of the proposed nonlocal computational homogenization technique for softening quasi-brittle materials.     

Mode Analysis with Autocorrelation Method (Single Time Series) in Tokamak

In this paper plasma mode analyzed with statistical method that designated Autocorrelation function. Auto correlation function used from one time series, so for this purpose we need one Minov coil. After autocorrelation analysis on mirnov coil data, spectral density diagram is plotted. Spectral density diagram from symmetries and trends can analyzed plasma mode. RHF fields effects with this method ate investigated in IR-T1 tokamak and results corresponded with multichannel methods such as SVD and FFT.