Development and Modeling of High Temperature Polymeric Heater

Polymers are generally known for their excellent insulative properties. The addition of carbonaceous fillers such as carbon black and graphite within a polymer matrix can impart electrical and thermal properties making them good conductors. The resulting composites can be used in applications requiring and/or ranging from electromagnetic and radio frequency interference (EMI/RFI) shielding, electrostatic discharge (ESD) and heaters/heating elements to which metals have been the materials of choice. The advantages of using such composites include cost reduction, part consolidation, chemical resistance, lighter weight, and ability to easily design into complex three dimensional shapes via injection molding. For this work, various conductive thermoplastic composites were investigated as a metal (Ni-chrome heating element) alternative and/or substitute for use as heating elements through mechanisms of Joule heating. First, composites and test specimen were prepared via melt extrusion and injection molding respectively. Thereafter, electrical thermal and mechanical properties were characterized using both ASTM and non ASTM techniques. Results were then modeled using statistical software to determine correlations between formulations to responses and whether these results are desired and or meaningful. Results from experiments indicated significant advantage in using semi-crystalline polymers as the base carrier due to the superior electrical properties at equivalent filler loading compared to amorphous based composites, a criterion in joule heating. It was also determined that heating rate and maximum/plateau temperature was mainly a function of specimen resistance (formulation parameter) and voltage setting. Finally, the model obtained for plateau temperature was found to be significant. This indicated it is possible to develop polymeric type heaters with operating temperatures above 100ðC (current technology) and as high as 200ðC. Moreover, these composites would have self regulating properties other than

Development and Modeling of High Temperature Polymeric Heater

Polymers are generally known for their excellent insulative properties. The addition of carbonaceous fillers such as carbon black and graphite within a polymer matrix can impart electrical and thermal properties making them good conductors. The resulting composites can be used in applications requiring and/or ranging from electromagnetic and radio frequency interference (EMI/RFI) shielding, electrostatic discharge (ESD) and heaters/heating elements to which metals have been the materials of choice. The advantages of using such composites include cost reduction, part consolidation, chemical resistance, lighter weight, and ability to easily design into complex three dimensional shapes via injection molding. For this work, various conductive thermoplastic composites were investigated as a metal (Ni-chrome heating element) alternative and/or substitute for use as heating elements through mechanisms of Joule heating. First, composites and test specimen were prepared via melt extrusion and injection molding respectively. Thereafter, electrical thermal and mechanical properties were characterized using both ASTM and non ASTM techniques. Results were then modeled using statistical software to determine correlations between formulations to responses and whether these results are desired and or meaningful. Results from experiments indicated significant advantage in using semi-crystalline polymers as the base carrier due to the superior electrical properties at equivalent filler loading compared to amorphous based composites, a criterion in joule heating. It was also determined that heating rate and maximum/plateau temperature was mainly a function of specimen resistance (formulation parameter) and voltage setting. Finally, the model obtained for plateau temperature was found to be significant. This indicated it is possible to develop polymeric type heaters with operating temperatures above 100ðC (current technology) and as high as 200ðC. Moreover, these composites would have self regulating properties other than

A Novel Hybrid Hand Instrumentation Technique for Root Canal Preparation

Introduction: Preparation of root canal system necessitates both enlargement and shaping of the complex root canal space together with disinfection of the easily accessible and hidden areas. The present article introduces a new manual root canal preparation technique and compares it with passive step-back and step-back regarding some items such as shaping efficacy, maintenance of working length and occurrence of procedural accidents. Methods and Materials: This canal preparation technique (Bolourchi Hybrid Technique-BHT) was compared with passive step-back and step-back root through preparation of 30 extracted human mandibular and maxillary molars. Three experienced endodontists evaluated the final radiographies for following items: 1) difficulty of the case 2) shaping efficacy 3) maintenance of working length 4) time of preparation. Two-way ANOVA was used to analyze the data. Multiple comparisons were done using the Tukey’s HSD. Results: Regarding shaping efficacy and maintenance of working length, BHT group showed significantly higher scores and scores for step-back group were significantly the lowest. The difference between BHT group and passive step-back on these items was not significant. No significant differences were found between the techniques in other assessed criteria except for occurrence of procedural accidents which was significantly higher in step-back group. Conclusion: Considering the advantages of this novel technique as well as its comparability to the present routine techniques, it can be considered as an available root preparation technique for teaching in dental schools.Keywords:Balanced Forced Technique; Hand Instrumentation; Hybrid Hand Instrumentation; Passive Step-Back; Root Canal Preparation; Step-Back

AN INDUSTRIAL APPLICATION OF IMPROVED PARTICLE SWARM OPTIMIZATION: AVAILABILITY ASSESSMENT OF ELECTROSTATIC PRECIPITATOR

The Electrostatic Precipitator (ESP) is common equipment used in thermal power plants and industrial mining plants such as steel, copper, and cement. ESP is installed to capture the dust in the exhaust gas of boilers or furnaces. The availability of ESP is vital for plants since any interruption in this device causes serious process problems and environmental pollution. As a result, the availability of ESP is crucial, and a comprehensive study in this area must be performed for maintenance activities. This paper presents a novel method for assessing complex equipment availability, such as ESP, based on improved dynamic particle swarm optimization (IDPSO). To evaluate the availability of ESP, all related systems, sub-systems, and all components of ESP must be considered. Availability assessment of ESP, consisting of many series-parallel sections and components, can be challenging and time-consuming. An IDPSO is used to search for the most probable states among numerous possible states. In addition, IDPSO overcomes shortcomings of standard PSO, such as falling into local optimums. The proposed method is applied to the actual data of an ESP installed at a copper factory. The results show the proposed method achieved an accuracy of 99.54 % in availability assessment

MEASUREMENT OF RIDER INDUCED LOADS DURING SIMULATED BICYCLING

Research related to bicycling has broadened in scope over the last decade. Prior to about 1975, the majority of bicycling related research was dedicated to topics surrounding the physiology of human performance. These early efforts served to stimulate interest in bicycling research with the result that more recent research has explored a diversity of topics ranging from fundamentals of muscle mechanics to measurement of foot/pedal loads. Despite the both broadened and intensified research activity, one topic, which has recei ved no attention to the authors I knowledge, is measurement of the complete loading induced by the rider on the bicycle frame. The importance of this topic lies in the applicability of the results to two areas, design analysis of bicycle components including the frame and biomechanical analysis of the pedalling process. The concern in the present article is with the biomechanical analysis

Oroclinal bending, distributed thrust and strike-slip faulting, and the accommodation of Arabia–Eurasia convergence in NE Iran since the Oligocene

Regional shortening is accommodated across NE Iran in response to the collision of Arabia with Eurasia. We examine how N–S shortening is achieved on major thrust systems bounding the eastern branch of the Alborz (east of 57°E), Sabzevar and Kuh-e-Sorkh mountain ranges, which lie south of the Kopeh Dagh mountains in NE Iran. Although these ranges have experienced relatively few large earthquakes over the last 50 yr, they have been subject to a number of devastating historical events at Neyshabur, Esfarayen and Sabzevar. A significant change in the tectonics of the eastern Alborz occurs directly south of the Central Kopeh Dagh, near 57°E. To the east, shortening occurs on major thrust faults which bound the southern margin of the range, resulting in significant crustal thickening, and forming peaks up to 3000 m high. Active shortening dies out eastward into Afghanistan, which is thought to belong to stable Eurasia. The rate of shortening across thrust faults bounding the south side of the eastern Alborz north of Neyshabur is determined using optically stimulated luminescence dating of displaced river deposits, and is likely to be 0.4–1.7 mm yr^(−1). Shortening across the Sabzevar range 150 km west of Neyshabur has previously been determined at 0.4–0.6 mm yr^(−1), although reassessment of the rate here suggests it may be as high as 1 mm yr^(−1). Migration of thrust faulting into foreland basins is common across NE Iran, especially in the Esfarayen region near 57°E, where the northward deflection of the East Alborz range reaches a maximum of 200 ± 20 km (from its presumed linear E–W strike at the beginning of the Oligocene). West of 57°E, the tectonics of the Alborz are affected by the westward motion of the South Caspian region, which results in the partitioning of shortening onto separate thrust and left-lateral strike-slip faults north and south of the range. At the longitude of 59°E, published GPS velocities indicate that 50 per cent of the overall shortening across NE Iran is accommodated in the Kopeh Dagh. The remaining 50 per cent regional shortening must therefore be accommodated south of the Kopeh Dagh, in the eastern Alborz and Kuh-e-Sorkh ranges. Assuming present day rates of slip and the fault kinematics are representative of the Late Cenozoic deformation in NE Iran, the total 200 ± 20 km N–S shortening across the eastern Alborz and Kopeh Dagh mountains since the beginning of uplift of the Kopeh Dagh basin would be accommodated in 30 ± 8 Ma. Although this extrapolation may be inappropriate over such a long timescale, the age is nevertheless consistent with geological estimates of post Early-to-Middle Oligocene (<30 Ma) for the onset of Kopeh Dagh uplift

An assessment of bicycle frame behaviour under various load conditions using numerical simulations

This paper outlines the use of a finite element model to simulate the behaviour for a standard steel bicycle frames under a range of measured load cases. These load cases include those measured both in the laboratory setting and also in the field, and include loads transmitted at key areas such as the dropouts and hub, the bottom bracket and drive, the headset and handlebars, and the seat post and saddle. The load cases analysed include static representations of dynamic bump situations which occur sporadically and also those which occur constantly or regularly such as those generated at the drive and handlebars during climbing or cruising. The resulting stresses within the bicycle are analysed in the context of frame performance relating to static and fatigue strengths and are also compared to similar load cases presented in the literature. Further research is required to understand the influence of tube profiles on frame strength, and to analyse the modes of failure for various bicycle designs and materials used under typical and extreme usage in order to understand the implications of design on safety

Optimum Lateral Load Distribution for Seismic Design of Nonlinear Shear-Buildings Considering Soil-Structure Interaction

The lateral load distributions specified by seismic design provisions are primarily based on elastic behaviour of fixed-base structures without considering the effects of soil-structure-interaction (SSI). Consequently, such load patterns may not be suitable for seismic design of non-linear flexible-base structures. In this paper, a practical optimization technique is introduced to obtain optimum seismic design loads for non-linear shear-buildings on soft soils based on the concept of uniform damage distribution. SSI effects are taken into account by using the cone model. Over 30,000 optimum load patterns are obtained for 21 earthquake excitations recorded on soft soils to investigate the effects of fundamental period of the structure, number of stories, ductility demand, earthquake excitation, damping ratio, damping model, structural post yield behaviour, soil flexibility and structural aspect ratio on the optimum load patterns. The results indicate that the proposed optimum load patterns can significantly improve the seismic performance of flexible-base buildings on soft soils

Progressive Preference Articulation for Decision Making in Multi-Objective Optimisation Problems

This paper proposes a novel algorithm for addressing multi-objective optimisation problems, by employing a progressive preference articu- lation approach to decision making. This enables the interactive incorporation of problem knowledge and decision maker preferences during the optimisation process. A novel progressive preference articulation mechanism, derived from a statistical technique, is herein proposed and implemented within a multi-objective framework based on evolution strategy search and hypervolume indicator selection. The proposed algo- rithm is named the Weighted Z-score Covariance Matrix Adaptation Pareto Archived Evolution Strategy with Hypervolume-sorted Adaptive Grid Algorithm (WZ-HAGA). WZ-HAGA is based on a framework that makes use of evolution strategy logic with covariance matrix adaptation to perturb the solutions, and a hypervolume indicator driven algorithm to select successful solutions for the subsequent generation. In order to guide the search towards interesting regions, a preference articulation procedure composed of four phases and based on the weighted z-score approach is employed. The latter procedure cascades into the hypervolume driven algorithm to perform the selection of the solutions at each generation. Numerical results against five modern algorithms representing the state-of-the-art in multi-objective optimisation demonstrate that the pro- posed WZ-HAGA outperforms its competitors in terms of both the hypervolume indicator and pertinence to the regions of interest

Covariance Matrix Adaptation Pareto Archived Evolution Strategy with Hypervolume-sorted Adaptive Grid Algorithm.

Real-world problems often involve the optimisation of multiple conflicting objectives. These problems, referred to as multi-objective optimisation problems, are especially challenging when more than three objectives are considered simultaneously. This paper proposes an algorithm to address this class of problems. The proposed algorithm is an evolutionary algorithm based on an evolution strategy framework, and more specifically, on the Covariance Matrix Adaptation Pareto Archived Evolution Strategy (CMA-PAES). A novel selection mechanism is introduced and integrated within the framework. This selection mechanism makes use of an adaptive grid to perform a local approximation of the hypervolume indicator which is then used as a selection criterion. The proposed implementation, named Covariance Matrix Adaptation Pareto Archived Evolution Strategy with Hypervolume-sorted Adaptive Grid Algorithm (CMA-PAES-HAGA), overcomes the limitation of CMA-PAES in handling more than two objectives and displays a remarkably good performance on a scalable test suite in five, seven, and ten-objective problems. The performance of CMA-PAES-HAGA has been compared with that of a competition winning meta-heuristic, representing the state-of-the-art in this sub-field of multi-objective optimisation. The proposed algorithm has been tested in a seven-objective real-world application, i.e. the design of an aircraft lateral control system. In this optimisation problem, CMA-PAES-HAGA greatly outperformed its competitors