Interacting functionally graded quantum wires/quantum dots with arbitrary shapes and general anisotropy within a distinct piezoelectric matrix

An accurate determination of the two- and three-dimensional electro-elastic fields of periodically as well as arbitrarily distributed interacting quantum wires (QWRs) and interacting quantum dots (QDs) of arbitrary shapes within a piezoelectric matrix is of particular interest. Both the QWR/QD and the barrier may be made of materials with distinct general rectilinear anisotropy in elastic, piezoelectric, and dielectric constants. The lattice mismatch between the QWR/QD and the barrier is accounted by prescribing an initial misfit strain field within the QWR/QD. Previous analytical treatments have neglected the distinction between the electro-mechanical properties of the QWR/QD and those of the barrier. This simplifying assumption is circumvented in the present work by using a novel electro-mechanical equivalent inclusion method in Fourier space (FEMEIM). Moreover, the theory can readily treat cases where the QWRs/QDs are multiphase or functionally graded (FG). It was proven that for two-dimensional problems of either a periodic or an arbitrary distribution of FG QWRs in a transversely isotropic piezoelectric barrier, the elastic and electric fields are electrically and elastically impotent, respectively, and no electric field would be induced in the medium provided that the rotational symmetry and polarization axes coincide. Some numerical examples of more frequent shapes and different distributions of indium nitride QDs/QWRs within transversely isotropic aluminum nitride barrier are solved

Voltage security evaluation based on perturbation method

This is the post-print version of the final paper published in International Journal of Electrical Power & Energy Systems. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2009 Elsevier B.V.This paper proposes a new algorithm for estimating voltage security margin. The algorithm is based on the perturbation method and has significant computational efficiency. The proposed algorithm can be used for on-line voltage security evaluation. It has been validated using IEEE-14, IEEE-30 and IEEE-57 bus systems. Results from the tests show higher efficiency and smaller error margins compared to continuation power flow (CPF) method. Voltage collapse is a serious threat to the security of stressed power systems; therefore, voltage security (VS) has become a major challenge for management of power systems. The motivation for this research is a direct consequence of the deregulation of electricity industries and markets worldwide

Hybrid mutation particle swarm optimisation method for available transfer capability enhancement

A Hybrid Mutation Particle Swarm Optimisation (HMPSO) technique for improved estimation of Available Transfer Capacity (ATC) is proposed in this paper. This is achieved by firstly comparing a typical application of the Particle Swarm Optimisation (PSO) technique with conventional Genetic Algorithm (GA) methods. Secondly, a multi-objective optimisation problem concerning optimal installation and capacity allocation of Flexible AC Transmission Systems (FACTS) devices is presented and demonstrated. Modern heuristic techniques such as PSO have been demonstrated to be suitable in solving non-linear power systems problems. The outcome of this research further demonstrates that with better utilisation of FACTS devices it is possible to improve transmission capabilities. The motivation of this research is a direct consequence of the deregulation of electricity industries and markets worldwide. The current deregulated environment provides transmission systems operators (TSO) with more options when procuring transmission services. The effectiveness of the proposed algorithm is demonstrated across a range of case studies and the results are validated through analyses conducted on IEEE 30-bus and 57-bus test systems

Outcomes of chronic total occlusion percutaneous coronary intervention from the RAIAN (RAjaie - Iran) registry

Objective: While most of the evidence in CTO interventions emerge from Western and Japanese studies, few data have been published up today from the Middle East. Objective of this study was to evaluate technical success rates and clinical outcomes of an Iranian population undergoing CTO PCI in a tertiary referral hospital. Moreover, we sought to evaluate the efficacy of our CTO teaching program. Methods: This is a retrospective single-center cohort study including 790 patients who underwent CTO PCI performed by operators with different volumes of CTOs PCI performed per year. According to PCI result, all patients have been divided into successful (n = 555, 70.3 %) and unsuccessful (n = 235, 29.7 %) groups. Study endpoints were Major Adverse Cardiovascular Events and Health Status Improvement evaluated using the Seattle Angina Questionnaire at one year. Results: A global success rate of 70 % for antegrade and 80 % for retrograde approach was shown despite the lack of some CTO-dedicated devices. During the enrollment period, the success rate increased significantly among operators with a lower number of CTO procedures per year. One-year MACE rate was similar in both successful and unsuccessful groups (13.5 % in successful and 10.6 % in unsuccessful group, p = 0.173). One year patients' health status improved significantly only in successful group. Conclusions: No significant differences of in-hospital and one-year MACE were found between the successful and unsuccessful groups. Angina symptoms and quality of life significantly improved after successful CTO PCI. The RAIAN registry confirmed the importance of operator expertise for CTO PCI success

Assessing Time between Arriving to Hospital and Administration of Streptokinase in Patients with Acute Myocardial Infarction in Emergency Department of Kerman University of Medical Sciences in 2003-4

Abstract: Introduction: Acute myocardial infarction is one of the major causes of mortality in developing countries such as Iran. One of the most important progresses in acute myocardial infarction is early administration of therombolytic agents such as streptokinase. This study was performed to determine the time interval from patients’ referral to the emergency wards to the introduction of thrombolytic therapy and the factors associated with delay in drug administration. Methods: In a period of 8 months, 130 patients with presumed acute myocardial infarction were investigated. In order to determine the causes of delay in streptokinase administration, duration of symptoms onset to drug administration was divided into 4 specified periods and measured in minutes. Results were analyzed using ANOVA and t-test. Results: Findings showed a mean elapsed time of 298 minutes between pain onset and referring to the emergency ward, 73 minutes between patient’s arrival and streptokinase administration. Mean time from symptom onset to drug infusion was 370 minutes. There was a delay of 2 hours in drug administration in 18% of patients. The most important causes of delay were long distance and delay of physicians and staff. Conclusion: Considering the findings, increasing people’s knowledge about the symptoms of heart problem, providing medical facilities and instruction of medical staff play important role in decreasing delay time in drug administration and increasing streptokinase output. Keywords: Myocardial infarction, Streptokinas

An environmental oriented model for optimum cut off grades in open pit mining projects to minimize acid mine drainage

Environmental concerns on mining activities started near the end of the 20th century and is still underway. Due to mining activities, the adverse environmental impact has been significant throughout the history of mankind, whereas the minerals produced by mining activities have been providing the basis for human civilization. The legacy of past mining practices is large quantities of acid generating waste materials and tailings that caused abounding acid mine drainage problems. Modern mining environmental management tends to focus on concerns over the impact of waste disposal on surface primarily in the form of tailings and waste materials structures. Sustainable development principles are being increasingly applied by mining companies in developed and developing countries. Operating costs per unit of operation is recognized to be one the most important sustainable mining practice indicator and cut off grade is considered to be a well-founded representative for this indicator. In this paper, a developed model for optimum cut off grades is presented that not only relies on economical aspects but also minimizes adverse environmental impact in the form of acid mine drainage elimination or mitigation against the approach of postponing the restoration/reclamation activities at the end of the project’s life

A NEW METHODOLOGY TO SOLVE JOINT ENERGY AND PRIMARY RESERVE SCHEDULING

Abstract The unit commitment problem has been broadly studied in recent years in many researches. However, this is not all of the important tasks for independent system operator. One of the most important tasks is the optimal provision of primary frequency regulation reserve with the lowest cost that should be considered in the unit commitment problem. Frequency control in power system, as an ancillary service, has closed dependence to hourly scheduling of energy. In this paper, a novel approach is proposed to solve simultaneous scheduling of energy and primary reserve using genetic algorithm. The proposed methodology is fast and simple against conventional methods. In addition, applicability of scheduled primary reserve has been considered in optimization process. Finally, simulation results for a 17 unit case study are presented in comparison with a related work. The simulation results using Matlab 2009a are presented which verify the effectiveness and robustness of the proposed method