Parameter selection in particle swarm optimisation: a survey

Nowadays, particle swarm optimisation (PSO) is one of the most commonly used optimisation techniques. However, PSO parameters significantly affect its computational behaviour. That is, while it exposes desirable computational behaviour with some settings, it does not behave so by some other settings, so the way for setting them is of high importance. This paper explains and discusses thoroughly about various existent strategies for setting PSO parameters, provides some hints for its parameter setting and presents some proposals for future research on this area. There exists no other paper in literature that discusses the setting process for all PSO parameters. Using the guidelines of this paper can be strongly useful for researchers in optimisation-related fields

Heuristic methods for solution of FACTS optimization problem in power systems

This paper presents a comprehensive review on various heuristic methods for solution of flexible AC transmission systems (FACTS) optimization problem in power systems. First, it classifies FACTS optimization methods into four main groups, then subdivides heuristic methods into different subsets and discusses thoroughly about characteristics, advantages and disadvantages of each heuristic subset. Finally, some hints for future researches on this area will be offered

Optimal placement of multi-type FACTS devices in power systems using evolution strategies

In this paper, Evolution Strategies (ES) is used to find optimal placement of FACTS devices in power systems. The goal of optimization is to maximize the system loadability. Optimization is based on finding locations and settings of FACTS devices. Simulations are implemented on IEEE 30-bus test system. From different types of FACTS devices, SVC, TCSC and UPFC are used in this research. The results show that using FACTS devices, the loadability of power system increases significantly. It also shows that there exists a maximum number of devices beyond which, the loadability of power system can not be increased. The implementation results of the method are promising and encouraging, so it is a good method for implementation on the FACTS optimization problem

Significance of compressional tectonic on pore pressure distribution in Perth Basin

The Perth Basin is one of the major tectonic structures along the western continental margin of Australia and was initially formed through the rifting and break-up of the Indian and Australian plates. The severe tectonic movements accompanied and occurred after the break-up are responsible for the most structural elements and for the distribution of pore pressure in the basin. Investigations on the well log data from the Perth Basin have identified shale intervals which are characterised as overpressured in some parts of the basin, whereas similar shale intervals found to be normally pressured in other parts of the basin. The phenomena of overpressure have frequently been reported while drilling the same intervals. Based on this research, sections with overpressure were observed in the majority of the wells in the basal section of the Kockatea shale where there were less tectonic activities have been recorded. Normal pore pressure was observed in shallower wells in the Kockatea shales which were located within uplifted sections that were more tectonically active areas. Based on the results of this research, the pore pressure distribution in the Kockatea Shale varied significantly from one part of the Perth Basin to another as a result of compressive tectonic stress. Compressional tectonic activities either induced fracturing in shallower localities (e.g. Beagle Ridge, Cadda Terrace and the adjacent terraces) or removed part of the Kockatea Shale as a result of faulting resulting in overpressures being released. Regions with less intensity of the tectonic activities showed an increase in pressure gradients as approaching away from the centre of uplift

Large Laryngeal Lipoma with Extra Laryngeal Component Mimics Mixed Form Laryngocele: A Case Report

Introduction: Lipomas are the most common benign neoplasms, occurring in any part of the body where fat is present. Their occurrence in the head and neck is not common. Here, we report a large laryngeal lipoma with extra laryngeal component, mimicking mixed form of laryngocele. Case presentation: A 47-year-old man presented with a 3-year history of hoarseness, intermittent dyspnea and mass sensation in the neck. The patient was submitted to indirect laryngoscopy; a large submucosal mass obliterating the left side of the supraglottic larynx and partially obstructing the airway was found. Enhanced computed tomography (CT) scan demonstrated non-enhancing homogeneous hypodense fat density mass lesion measured 55*45*32 mm, extending through the thyroid membrane to parapharyngeal space and showing extra laryngeal component with an intact laryngeal mucosa lesion. Open surgery of the submucosal mass was performed. Pathology examination confirmed the diagnosis of lipoma. Conclusion: Neck lipomas are also typically asymptomatic, but can compress nearby structures, causing symptoms such as hoarseness, dyspnea and dysphagia. When symptomatic, they should be removed via surgery

Large Laryngeal Lipoma with Extra Laryngeal Component Mimics Mixed Form Laryngocele: A Case Report

Introduction: Lipomas are the most common benign neoplasms, occurring in any part of the body where fat is present. Their occurrence in the head and neck is not common. Here, we report a large laryngeal lipoma with extra laryngeal component, mimicking mixed form of laryngocele. Case presentation: A 47-year-old man presented with a 3-year history of hoarseness, intermittent dyspnea and mass sensation in the neck. The patient was submitted to indirect laryngoscopy; a large submucosal mass obliterating the left side of the supraglottic larynx and partially obstructing the airway was found. Enhanced computed tomography (CT) scan demonstrated non-enhancing homogeneous hypodense fat density mass lesion measured 55*45*32 mm, extending through the thyroid membrane to parapharyngeal space and showing extra laryngeal component with an intact laryngeal mucosa lesion. Open surgery of the submucosal mass was performed. Pathology examination confirmed the diagnosis of lipoma. Conclusion: Neck lipomas are also typically asymptomatic, but can compress nearby structures, causing symptoms such as hoarseness, dyspnea and dysphagia. When symptomatic, they should be removed via surgery

A Case Report of a Huge Mesenteric Cyst in a 5-Year-Old Girl: A Rare and Challenging Finding in Radiological Assessment

Introduction: Mesenteric cysts are rare benign intra-abdominal vesicles with various clinical presentations. They almost located in the mesentery of the small intestine. The selective therapeutic method is complete surgical excision, however more than half need resection and bowel anastomosis. Case presentation: Here, we presented a 5-year-old girl with a huge mesenteric cyst (15×14cm2) mesenteric cyst that was excised surgically., which the diagnosis confirmed by computed tomography scan and managed through surgical excision. Conclusion: Acute abdominal pain may be due to the presence of mesenteric cysts, but it is not always possible to differentiate and diagnose it preoperatively, and this challenge especially exists in the case of bulky masses. it is recommended to choose primary radical, surgical treatment in case of intra-abdominal cystic mass in the pediatric age

Analyzing and studying educational pyramid and changes in demographical indices of Tehran students during the school years 2000-2010

One of the effective factors in planning is paying attention to the increase and decrease of student population. In this study, using a variety of resources, it has been attempted that the growth changes and population decrease in the student population of Tehran in a 10-year period and considering the measures such as population density in-class students, the educational staff ratio, academic pyramid, the separation of school, number of classes and other aspects will be dealt with. Obviously, the results and findings of this potential research could be used in educational planning and population policy. In the present study, the method of data collection was done using the quantitative techniques of demography and a variety of statistical calculations. The research findings showed that the student population, number of classes and schools and the staff of ministry of education are being significantly decreased and has been associated with a negative growth rate in all levels

Analyzing and studying educational pyramid and changes in demographical indices of Tehran students during the school years 2000-2010

One of the effective factors in planning is paying attention to the increase and decrease of student population. In this study, using a variety of resources, it has been attempted that the growth changes and population decrease in the student population of Tehran in a 10-year period and considering the measures such as population density in-class students, the educational staff ratio, academic pyramid, the separation of school, number of classes and other aspects will be dealt with. Obviously, the results and findings of this potential research could be used in educational planning and population policy. In the present study, the method of data collection was done using the quantitative techniques of demography and a variety of statistical calculations. The research findings showed that the student population, number of classes and schools and the staff of ministry of education are being significantly decreased and has been associated with a negative growth rate in all levels