Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 406

Search results for: pole placement

406 Using Adaptive Pole Placement Control Strategy for Active Steering Safety System

Authors: Hadi Adibi-Asl, Alireza Doosthosseini, Amir Taghavipour

Abstract:

This paper studies the design of an adaptive control strategy to tune an active steering system for better drivability and maneuverability. In the first step, adaptive control strategy is applied to estimate the uncertain parameters on-line (e.g. cornering stiffness), then the estimated parameters are fed into the pole placement controller to generate corrective feedback gain to improve the steering system dynamic’s characteristics. The simulations are evaluated for three types of road conditions (dry, wet, and icy), and the performance of the adaptive pole placement control (APPC) are compared with pole placement control (PPC) and a passive system. The results show that the APPC strategy significantly improves the yaw rate and side slip angle of a bicycle plant model.

Keywords: adaptive control, active steering, pole placement, vehicle dynamics

Procedia PDF Downloads 362
405 Regional Pole Placement by Saturated Power System Stabilizers

Authors: Hisham M. Soliman, Hassan Yousef

Abstract:

This manuscript presents new results on design saturated power system stabilizers (PSS) to assign system poles within a desired region for achieving good dynamic performance. The regional pole placement is accomplished against model uncertainties caused by different load conditions. The design is based on a sufficient condition in the form of linear matrix inequalities (LMI) which forces the saturated nonlinear controller to lie within the linear zone. The controller effectiveness is demonstrated on a single machine infinite bus system.

Keywords: power system stabilizer, saturated control, robust control, regional pole placement, linear matrix inequality (LMI)

Procedia PDF Downloads 484
404 Suitable Tuning Method Selection for PID Controller Used in Digital Excitation System of Brushless Synchronous Generator

Authors: Deepak M. Sajnekar, S. B. Deshpande, R. M. Mohril

Abstract:

At present many rotary excitation control system are using analog type of Automatic Voltage Regulator which now started to replace with the digital automatic voltage regulator which is provided with PID controller and tuning of PID controller is a challenging task. The cases where digital excitation control system is used tuning of PID controller are still carried out by pole placement method. Tuning of PID controller used for static excitation control system is not challenging because it does not involve exciter time constant. This paper discusses two methods of tuning PID controller i.e. Pole placement method and pole zero cancellation method. GUI prepared for both the methods on the platform of MATLAB. Using this GUI, performance results and time required for tuning for both the methods are compared. Sensitivity of the methods is also presented with parameter variation like loop gain ‘K’ and exciter time constant ‘te’.

Keywords: digital excitation system, automatic voltage regulator, pole placement method, pole zero cancellation method

Procedia PDF Downloads 399
403 Robust Control of a Dynamic Model of an F-16 Aircraft with Improved Damping through Linear Matrix Inequalities

Authors: J. P. P. Andrade, V. A. F. Campos

Abstract:

This work presents an application of Linear Matrix Inequalities (LMI) for the robust control of an F-16 aircraft through an algorithm ensuring the damping factor to the closed loop system. The results show that the zero and gain settings are sufficient to ensure robust performance and stability with respect to various operating points. The technique used is the pole placement, which aims to put the system in closed loop poles in a specific region of the complex plane. Test results using a dynamic model of the F-16 aircraft are presented and discussed.

Keywords: F-16 aircraft, linear matrix inequalities, pole placement, robust control

Procedia PDF Downloads 241
402 Performance Comparisons between PID and Adaptive PID Controllers for Travel Angle Control of a Bench-Top Helicopter

Authors: H. Mansor, S. B. Mohd-Noor, T. S. Gunawan, S. Khan, N. I. Othman, N. Tazali, R. B. Islam

Abstract:

This paper provides a comparative study on the performances of standard PID and adaptive PID controllers tested on travel angle of a 3-Degree-of-Freedom (3-DOF) Quanser bench-top helicopter. Quanser, a well-known manufacturer of educational bench-top helicopter has developed Proportional Integration Derivative (PID) controller with Linear Quadratic Regulator (LQR) for all travel, pitch and yaw angle of the bench-top helicopter. The performance of the PID controller is relatively good; however its performance could also be improved if the controller is combined with adaptive element. The objective of this research is to design adaptive PID controller and then compare the performances of the adaptive PID with the standard PID. The controller design and test is focused on travel angle control only. Adaptive method used in this project is self-tuning controller, which controller’s parameters are updated online. Two adaptive algorithms those are pole-placement and deadbeat have been chosen as the method to achieve optimal controller’s parameters. Performance comparisons have shown that the adaptive (deadbeat) PID controller has produced more desirable performance compared to standard PID and adaptive (pole-placement). The adaptive (deadbeat) PID controller attained very fast settling time (5 seconds) and very small percentage of overshoot (5% to 7.5%) for 10° to 30° step change of travel angle.

Keywords: adaptive control, deadbeat, pole-placement, bench-top helicopter, self-tuning control

Procedia PDF Downloads 400
401 A 3Y/3Y Pole-Changing Winding of High-Power Asynchronous Motors

Authors: Gábor Kovács

Abstract:

Requirement for pole-changing motors emerged at the very early times of asynchronous motor design. Different solutions have been elaborated and some of them are generally used. An alternative is the so called 3 Y/3 Y pole-changing winding. This paper deals with high power application of this solution. A complete and comprehensive study is introduced, including features and design guidelines. The method presented in this paper is especially suitable for pole numbers being close to each other. The study also reveals that the method is more advantageous then the existing solutions for high power motors with 1:3 pole ratio. Using this motor, a new and complete drive supply system has been proposed as most appropriate arrangement of high power main naval propulsion drive. Further, the method makes possible to extend the pole ratio to 1:6, 1:9, 1:12, etc. At the end, the proposal is further extended to the here so far missing 1:4, 1:5, 1:7 etc. pole ratios. A complete proposal for the theoretically infinite range has been given in this way.

Keywords: induction motor, pole changing 3Y/3Y, pole phase modulation, pole changing 1:3, 1:6

Procedia PDF Downloads 104
400 Brand Placement Strategies in Turkey: The Case of “Yalan Dünya”

Authors: Burçe Boyraz

Abstract:

This study examines appearances of brand placement as an alternative communication strategy in television series by focusing on Yalan Dünya which is one of the most popular television series in Turkey. Consequently, this study has a descriptive research design and quantitative content analysis method is used in order to analyze frequency and time data of brand placement appearances in first 3 seasons of Yalan Dünya with 16 episodes. Analysis of brand placement practices in Yalan Dünya is dealt in three categories: episode-based analysis, season-based analysis and comparative analysis. At the end, brand placement practices in Yalan Dünya are evaluated in terms of type, form, duration and legal arrangements. As a result of this study, it is seen that brand placement plays a determinant role in Yalan Dünya content. Also, current legal arrangements make brand placement closer to other traditional communication strategies instead of differing brand placement from them distinctly.

Keywords: advertising, alternative communication strategy, brand placement, Yalan Dünya

Procedia PDF Downloads 175
399 A Hybrid Method for Determination of Effective Poles Using Clustering Dominant Pole Algorithm

Authors: Anuj Abraham, N. Pappa, Daniel Honc, Rahul Sharma

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In this paper, an analysis of some model order reduction techniques is presented. A new hybrid algorithm for model order reduction of linear time invariant systems is compared with the conventional techniques namely Balanced Truncation, Hankel Norm reduction and Dominant Pole Algorithm (DPA). The proposed hybrid algorithm is known as Clustering Dominant Pole Algorithm (CDPA) is able to compute the full set of dominant poles and its cluster center efficiently. The dominant poles of a transfer function are specific eigenvalues of the state space matrix of the corresponding dynamical system. The effectiveness of this novel technique is shown through the simulation results.

Keywords: balanced truncation, clustering, dominant pole, Hankel norm, model reduction

Procedia PDF Downloads 523
398 A Pole Radius Varying Notch Filter with Transient Suppression for Electrocardiogram

Authors: Ramesh Rajagopalan, Adam Dahlstrom

Abstract:

Noise removal techniques play a vital role in the performance of electrocardiographic (ECG) signal processing systems. ECG signals can be corrupted by various kinds of noise such as baseline wander noise, electromyographic interference, and power-line interference. One of the significant challenges in ECG signal processing is the degradation caused by additive 50 or 60 Hz power-line interference. This work investigates the removal of power line interference and suppression of transient response for filtering noise corrupted ECG signals. We demonstrate the effectiveness of Infinite Impulse Response (IIR) notch filter with time varying pole radius for improving the transient behavior. The temporary change in the pole radius of the filter diminishes the transient behavior. Simulation results show that the proposed IIR filter with time varying pole radius outperforms traditional IIR notch filters in terms of mean square error and transient suppression.

Keywords: notch filter, ECG, transient, pole radius

Procedia PDF Downloads 300
397 Global Optimization Techniques for Optimal Placement of HF Antennas on a Shipboard

Authors: Mustafa Ural, Can Bayseferogulari

Abstract:

In this work, radio frequency (RF) coupling between two HF antennas on a shipboard platform is minimized by determining an optimal antenna placement. Unlike the other works, the coupling is minimized not only at single frequency but over the whole frequency band of operation. Similarly, GAO and PSO, are used in order to determine optimal antenna placement. Throughout this work, outputs of two optimization techniques are compared with each other in terms of antenna placements and coupling results. At the end of the work, far-field radiation pattern performances of the antennas at their optimal places are analyzed in terms of directivity and coverage in order to see that.

Keywords: electromagnetic compatibility, antenna placement, optimization, genetic algorithm optimization, particle swarm optimization

Procedia PDF Downloads 116
396 Stabilization of a Three-Pole Active Magnetic Bearing by Hybrid Control Method in Static Mode

Authors: Mahdi Kiani, Hassan Salarieh, Aria Alasty, S. Mahdi Darbandi

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The design and implementation of the hybrid control method for a three-pole active magnetic bearing (AMB) is proposed in this paper. The system is inherently nonlinear and conventional nonlinear controllers are a little complicated, while the proposed hybrid controller has a piecewise linear form, i.e. linear in each sub-region. A state-feedback hybrid controller is designed in this study, and the unmeasurable states are estimated by an observer. The gains of the hybrid controller are obtained by the Linear Quadratic Regulator (LQR) method in each sub-region. To evaluate the performance, the designed controller is implemented on an experimental setup in static mode. The experimental results show that the proposed method can efficiently stabilize the three-pole AMB system. The simplicity of design, domain of attraction, uncomplicated control law, and computational time are advantages of this method over other nonlinear control strategies in AMB systems.

Keywords: active magnetic bearing, three pole AMB, hybrid control, Lyapunov function

Procedia PDF Downloads 266
395 Experimental Study of the Fan Electric Drive Based on a Two-Speed Motor in Dynamic Modes

Authors: Makhsud Bobojanov, Dauletbek Rismukhamedov, Furkat Tuychiev, Khusniddin Shamsutdionov

Abstract:

The article presents the results of experimental study of a two-speed asynchronous motor 4A80B6/4U3 with pole-changing winding on a fan drive VSUN 160x74-0.55-4 in static and dynamic modes. A prototype of a pole-changing Motor was made based on the results of the calculation and the performance and mechanical characteristics of the Motor were removed at the experimental stand, as well as useful capacities and other parameters from both poles were determined. In dynamic mode, the curves of changes of torque and current of the stator were removed by direct start, constant speed operation, by switching of speeds and stopping.

Keywords: two speed motor, pole-changing motor, electric drive of fan, dynamic modes

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394 Using Dynamic Bayesian Networks to Characterize and Predict Job Placement

Authors: Xupin Zhang, Maria Caterina Bramati, Enrest Fokoue

Abstract:

Understanding the career placement of graduates from the university is crucial for both the qualities of education and ultimate satisfaction of students. In this research, we adapt the capabilities of dynamic Bayesian networks to characterize and predict students’ job placement using data from various universities. We also provide elements of the estimation of the indicator (score) of the strength of the network. The research focuses on overall findings as well as specific student groups including international and STEM students and their insight on the career path and what changes need to be made. The derived Bayesian network has the potential to be used as a tool for simulating the career path for students and ultimately helps universities in both academic advising and career counseling.

Keywords: dynamic bayesian networks, indicator estimation, job placement, social networks

Procedia PDF Downloads 297
393 The International Field Placement: Experience in Vietnam Social Work International Placement Programme

Authors: Ngo Thi Thanh Mai, Nguyen Thu Ha, Frances Crawford

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The demand for developing international social work field education is on the rise. Global foreign universities have considered international collaboration and cross-cultural perspective as an essential part of their social work training curriculum. International placement program at Faculty of Social Work (FSW), Hanoi National University of Education (HNUE) has met the need of international social work students, as well as the institutions involved in achieving social work professional social work knowledge in the Vietnamese context. This program has also lead to a long-term collaboration between HNUE and several global institutions in developing social work education, research and practice skill. This paper focuses on the benefits and challenges of students who involved in the global placement programme at Faculty of Social Work (FSW), Hanoi National University of Education (HNUE) and content of international field education provided to the international students based on the experience of the authors. Study results indicated that the participants have opportunity them to explore a new culture and social work system abroad especially in the Vietnamese context. However, there are still difficulties that international students have to face during different phases of the exchange process such as language and communication barriers, cultural value differences, insufficient support and supervision during placement. Basing on these results, the authors intend to propose some recommendations to enhance the programme activities such as pre-departure orientation, support and supervision during placement, cultural exchange and follow-up activities.

Keywords: social work education, social work, international placement, field placement, Vietnam

Procedia PDF Downloads 66
392 Optimal Design of Reference Node Placement for Wireless Indoor Positioning Systems in Multi-Floor Building

Authors: Kittipob Kondee, Chutima Prommak

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In this paper, we propose an optimization technique that can be used to optimize the placements of reference nodes and improve the location determination performance for the multi-floor building. The proposed technique is based on Simulated Annealing algorithm (SA) and is called MSMR-M. The performance study in this work is based on simulation. We compare other node-placement techniques found in the literature with the optimal node-placement solutions obtained from our optimization. The results show that using the optimal node-placement obtained by our proposed technique can improve the positioning error distances up to 20% better than those of the other techniques. The proposed technique can provide an average error distance within 1.42 meters.

Keywords: indoor positioning system, optimization system design, multi-floor building, wireless sensor networks

Procedia PDF Downloads 170
391 Controller Design Using GA for SMC Systems

Authors: Susy Thomas, Sajju Thomas, Varghese Vaidyan

Abstract:

This paper considers SMCs using linear feedback with switched gains and proposes a method which can minimize the pole perturbation. The method is able to enhance the robustness property of the controller. A pre-assigned neighborhood of the ‘nominal’ positions is assigned and the system poles are not allowed to stray out of these bounds even when parameters variations/uncertainties act upon the system. A quasi SMM is maintained within the assigned boundaries of the sliding surface.

Keywords: parameter variations, pole perturbation, sliding mode control, switching surface, robust switching vector

Procedia PDF Downloads 266
390 A Study on the Effect of Rib Structure in Spoke-Type PMSM

Authors: Hyun-Soo Seol, In-Gun Kim, Hyun Seok Hong, Dong-Woo Kang, Ju Lee

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Rotor of Spoke-Type PMSM is divided into permanent magnet and rotor core. Moreover, rotor core is composed of pole-piece, Bridge and rib. Piece between the permanent magnet N and S poles is pole-piece. Bridge and rib hold pole-piece. In the case of pole-piece and bridge, it is essential structure of Spoke-Type PMSM. However, Rib can be selected by the designer depending on the operating conditions and constraints. If rib is present in the rotor, rib which acts in the leak path generates a leakage flux. Although the leakage flux reduces the torque in low speed, it expands speed range in high speed. So, there is a relationship of trade off. Viewed from the standpoint of permanent magnet demagnetization, since the magnetic flux by the stator winding leaks to the rib, it is an advantage. In addition, rib affects the safety factor of the rotor. For application required high speed operation, since the securing the safety factor of the rotor is important, rib structure is advantageous. On the other hand, in the case of the application that does not require high speed operation, it is desirable to increase the output power by designing without rib. In this paper, Effects on rib structure is analyzed in detail and this paper provides designer with information about rotor design of spoke-type PMSM according to rib structure.

Keywords: spoke-Type PMSM, rotor shape, rib, operation range

Procedia PDF Downloads 318
389 Organising Field Practicum for International Social Work Students through Creative Projects in the Community Sector in Elderly Care: An Evaluation of the Placement Experiences

Authors: Kalpana Goel

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Australian social work schools are finding it difficult to find appropriate placements for the increasing number of international students enrolled in their Master of Social Work qualifying (MSWQ) programs. Anecdotally, it has been noticed that fewer social work students are ready to work with older people whose numbers are rising globally. An innovative and unique placement for international students enrolled in the MSWQ at one Australian university was organised in partnership with a community-based service working with older clients to meet two objectives: increasing the number of suitable placements for international students and preparing social work students to work with older people. Creative activities and projects were designed to provide meaningful engagement and experience in working with older people in the community. Students participated in a number of projects that were matched with their interest and capability in a 500-hour placement. The students were asked to complete an online survey after all work for the placement had been completed. The areas of assessment were: self-perceived change in perception towards age and older people, valued field placement experiences including reflective practice, knowledge and skill development, and constraints and challenges experienced in the placement. Findings revealed students’ increased level of confidence in applying social work theory to practice, developing effective communication and interpersonal skills, and use of innovation and creativity in preparing well-being plans with older adults. Challenges and constraints related to their limited English language ability and lack of cultural knowledge of the host society. It was recognised that extra support for these students and more planning in the beginning phase of placement are vital to placement success. Caution in matching students with clients of similar cultural background must be exercised to ensure that there is equity in task allocation and opportunities for wider experiences.

Keywords: field placement, international students, older people, social work

Procedia PDF Downloads 96
388 Optimal Wind Based DG Placement Considering Monthly Changes Modeling in Wind Speed

Authors: Belal Mohamadi Kalesar, Raouf Hasanpour

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Proper placement of Distributed Generation (DG) units such as wind turbine generators in distribution system are still very challenging issue for obtaining their maximum potential benefits because inappropriate placement may increase the system losses. This paper proposes Particle Swarm Optimization (PSO) technique for optimal placement of wind based DG (WDG) in the primary distribution system to reduce energy losses and voltage profile improvement with four different wind levels modeling in year duration. Also, wind turbine is modeled as a DFIG that will be operated at unity power factor and only one wind turbine tower will be considered to install at each bus of network. Finally, proposed method will be implemented on widely used 69 bus power distribution system in MATLAB software environment under four scenario (without, one, two and three WDG units) and for capability test of implemented program it is supposed that all buses of standard system can be candidate for WDG installing (large search space), though this program can consider predetermined number of candidate location in WDG placement to model financial limitation of project. Obtained results illustrate that wind speed increasing in some months will increase output power generated but this can increase / decrease power loss in some wind level, also results show that it is required about 3MW WDG capacity to install in different buses but when this is distributed in overall network (more number of WDG) it can cause better solution from point of view of power loss and voltage profile.

Keywords: wind turbine, DG placement, wind levels effect, PSO algorithm

Procedia PDF Downloads 377
387 Rumour Containment Using Monitor Placement and Truth Propagation

Authors: Amrah Maryam

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The emergence of online social networks (OSNs) has transformed the way we pursue and share information. On the one hand, OSNs provide great ease for the spreading of positive information while, on the other hand, they may also become a channel for the spreading of malicious rumors and misinformation throughout the social network. Thus, to assure the trustworthiness of OSNs to its users, it is of vital importance to detect the misinformation propagation in the network by placing network monitors. In this paper, we aim to place monitors near the suspected nodes with the intent to limit the diffusion of misinformation in the social network, and then we also detect the most significant nodes in the network for propagating true information in order to minimize the effect of already diffused misinformation. Thus, we initiate two heuristic monitor placement using articulation points and truth propagation using eigenvector centrality. Furthermore, to provide real-time workings of the system, we integrate both the monitor placement and truth propagation entities as well. To signify the effectiveness of the approaches, we have carried out the experiment and evaluation of Stanford datasets of online social networks.

Keywords: online social networks, monitor placement, independent cascade model, spread of misinformation

Procedia PDF Downloads 72
386 A Study of Transferable Skills for Work-Based Learning (WBL) Assessment

Authors: Abdool Qaiyum Mohabuth

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Transferrable skills are learnt abilities which are mainly acquired when experiencing work. University students have the opportunities to develop the knowledge and aptitude at work when they undertake WBL placement during their studies. There is a range of transferrable skills which students may acquire at their placement settings. Several studies have tried to identify a core set of transferrable skills which students can acquire at their placement settings. However, the different lists proposed have often been criticised for being exhaustive and duplicative. In addition, assessing the achievement of students on practice learning based on the transferrable skills is regarded as being complex and tedious due to the variability of placement settings. No attempt has been made in investigating whether these skills are assessable at practice settings. This study seeks to define a set of generic transferrable skills that can be assessed during WBL practice. Quantitative technique was used involving the design of two questionnaires. One was administered to University of Mauritius students who have undertaken WBL practice and the other was slightly modified, destined to mentors who have supervised and assessed students at placement settings. To obtain a good representation of the student’s population, the sample considered was stratified over four Faculties. As for the mentors, probability sampling was considered. Findings revealed that transferrable skills may be subject to formal assessment at practice settings. Hypothesis tested indicate that there was no significant difference between students and mentors as regards to the application of transferrable skills for formal assessment. A list of core transferrable skills that are assessable at any practice settings has been defined after taking into account their degree of being generic, extent of acquisition at work settings and their consideration for formal assessment. Both students and mentors assert that these transferrable skills are accessible at work settings and require commitment and energy to be acquired successfully.

Keywords: knowledge, skills, assessment, placement, mentors

Procedia PDF Downloads 207
385 The Triad Experience: Benefits and Drawbacks of the Paired Placement of Student Teachers in Physical Education

Authors: Todd Pennington, Carol Wilkinson, Keven Prusak

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Traditional models of student teaching practices typically involve the placement of a student teacher with an experienced mentor teacher. However, due to the ever-decreasing number of quality placements, an alternative triad approach is the paired placement of student teachers with one mentor teacher in a community of practice. This study examined the paired-placement of student teachers in physical education to determine the benefits and drawbacks after a 14-week student teaching experience. PETE students (N = 22) at a university in the United States were assigned to work in a triad with a student teaching partner and a mentor teacher, making up eleven triads for the semester. The one exception was a pair that worked for seven weeks at an elementary school and then for seven weeks at a junior high school, thus having two mentor teachers and participating in two triads. A total of 12 mentor teachers participated in the study. All student teachers and mentor teachers volunteered and agreed to participate. The student teaching experience was structured so that students engaged in: (a) individual teaching (one teaching the lesson with the other observing), (b) co-planning, and (c) peer coaching. All students and mentor teachers were interviewed at the conclusion of the experience. Using interview data, field notes, and email response data, the qualitative data was analyzed using the constant comparative method. The benefits of the paired placement experience emerged into three categories (a) quality feedback, (b) support, and (c) collaboration. The drawbacks emerged into four categories (a) unrealistic experience, (b) laziness in preparation, (c) lack of quality feedback, and (d) personality mismatch. Recommendations include: providing in-service training prior to student teaching to optimize the triad experience, ongoing seminars throughout the experience specifically designed for triads, and a hybrid model of paired placement for the first half of student teaching followed by solo student teaching for the second half of the experience.

Keywords: community of practice, paired placement, physical education, student teaching

Procedia PDF Downloads 334
384 Delamination Fracture Toughness Benefits of Inter-Woven Plies in Composite Laminates Produced through Automated Fibre Placement

Authors: Jayden Levy, Garth M. K. Pearce

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An automated fibre placement method has been developed to build through-thickness reinforcement into carbon fibre reinforced plastic laminates during their production, with the goal of increasing delamination fracture toughness while circumventing the additional costs and defects imposed by post-layup stitching and z-pinning. Termed ‘inter-weaving’, the method uses custom placement sequences of thermoset prepreg tows to distribute regular fibre link regions in traditionally clean ply interfaces. Inter-weaving’s impact on mode I delamination fracture toughness was evaluated experimentally through double cantilever beam tests (ASTM standard D5528-13) on [±15°]9 laminates made from Park Electrochemical Corp. E-752-LT 1/4” carbon fibre prepreg tape. Unwoven and inter-woven automated fibre placement samples were compared to those of traditional laminates produced from standard uni-directional plies of the same material system. Unwoven automated fibre placement laminates were found to suffer a mostly constant 3.5% decrease in mode I delamination fracture toughness compared to flat uni-directional plies. Inter-weaving caused significant local fracture toughness increases (up to 50%), though these were offset by a matching overall reduction. These positive and negative behaviours of inter-woven laminates were respectively found to be caused by fibre breakage and matrix deformation at inter-weave sites, and the 3D layering of inter-woven ply interfaces providing numerous paths of least resistance for crack propagation.

Keywords: AFP, automated fibre placement, delamination, fracture toughness, inter-weaving

Procedia PDF Downloads 115
383 Effects of Structure Shape Optimizing Techniques on the Performance of a Large Scale Wound Rotor Synchronous Machine

Authors: N. N. Siphepho, K. S. Garner

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Wound rotor synchronous machines with fractional slot nonoverlapping windings are attractive for low-speed, grid-connected wind applications. They are excited by direct current eliminating the need for permanent magnets, whose availability and price keep on fluctuating. Wound rotor synchronous machines are best suited for grid connection applications as they provide ample flux variation through changing the field current, thereby meeting grid code requirements for reactive power compensation without a need for external equipment. They are characterised by a high pole number and a slot number which is not a multiple of the pole number, and as a result, they can be used together with less gear stages which are advantageous in that it reduces gear costs and helps reduce points of system failure. The fractional slot non overlapping winding helps to greatly reduce the overall cost of the machine by minimizing the end winding length, allowing for a higher slot fill, ensuring a good fault tolerance capability of the machine and simplifying the manufacturing process by decreasing the number of stator slots and consequently improving the structural integrity of the machine. The main drawback of this kind of winding is high harmonic content in the air gap magneto-motive force waveform, which is evident by the presence of high torque ripples and increased rotor core losses leading to a depreciated overall machine performance. This paper seeks to study the effects of pole-placed flux barriers and pole shaping techniques on the performance characteristics of a large-scale wound rotor synchronous machine. To perform such a task, a 3MW, 400V,16 pole, 18 slots, double layer wound rotor synchronous machine is designed and analyzed using a python-based in-house static, 2D time stepped finite element method called SEMFEM and verified in the commercial transient finite element method software, Ansys Maxwell.

Keywords: eccentricity, flux barrier, magneto-motive force harmonics, minimum air gap, pole shaping, wound rotor synchronous machines

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382 Brand Placement Practices in the Movies and Their Importance on Brand Recall

Authors: Elif Esiyok

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Brand placement practices have become a popular advertising strategy, which is widely used in movies. Whether these brands are remembered by the audience after the film, or if they affect the purchasing preferences of the consumers has become one of the most important topics in the field of advertising. From this point, in this study, the "Devil Wears Prada" movie which includes high amount of brand placements is chosen. The movie watched to the undergraduate students in Turkey to measure the impact of brand placements on the attitudes of the consumers relating with a specific brand. In total 100 students were the subjects of this study. The participants were selected through using a simple random sampling method. The findings revealed that there is a significant difference between male and females in terms of brand recall. Female students were remembered the fashion brands more than the males, whereas males generally recalled the automotive brands and restaurant names.

Keywords: brand placement, brand recall, advertising, media

Procedia PDF Downloads 87
381 Employability Skills: Students' Perspectives Post Work Placement Experience

Authors: Mamie Y. Griffin, Pedro Coelhoso

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Employability skills of university graduates remain an ongoing topic for discussion and debate. Numerous studies highlight the expressed concerns of governments and industries about higher education’s ability to develop workforce-ready graduates. An often cited solution is the use of internships to equip students with necessary employability skills. The literature is well documented with studies from the perspectives of multiple entities including employers and university faculty, mostly in the western world. Fewer studies examine the perception of students, and even fewer studies are based on students in Gulf countries. This paper assesses the status of employability skills from the perspective of students within a United Arab Emirates (UAE) institution based on their completion of a semester-long work placement experience. Using a largely qualitative instrument, students reported the essential skills needed in the workplace, classroom activities that most prepared students to use such skills in the workplace, and the various challenges they encountered. Implications for academic and professional practitioners are discussed. Findings and recommendations are informative for curriculum development as well as economic and workforce development agencies.

Keywords: employability skills, work placement experience, Gulf countries, workforce preparedness, work placement

Procedia PDF Downloads 279
380 Effects of Array Electrode Placement on Identifying Localised Muscle Fatigue

Authors: Mohamed R. Al-Mulla, Bader Al-Bader, Firouz K. Ghaaedi, Francisco Sepulveda

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Surface electromyography (sEMG) is utilised in numerous studies on muscle activity. In the beginning, single electrodes were utilised; however, the newest approach is to use an array of electrodes or a grid of electrodes to improve the accuracy of the recorded reading. This research focuses on electrode placement on the biceps brachii, using an array of electrodes placed longitudinal and diagonally on the muscle belly. Trials were conducted on four healthy males, with sEMG signal acquisition from fatiguing isometric contractions. The signal was analysed using the power spectrum density. The separation between the two classes of fatigue (non-fatigue and fatigue) was calculated using the Davies-Bouldin Index (DBI). Results show that higher separability between the fatigue content of the sEMG signal when placed longitudinally, in the same direction as the muscle fibers.

Keywords: array electrodes, biceps brachii, electrode placement, EMG, isometric contractions, muscle fatigue

Procedia PDF Downloads 287
379 H-Infinity and RST Position Controllers of Rotary Traveling Wave Ultrasonic Motor

Authors: M. Brahim, I. Bahri, Y. Bernard

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Traveling Wave Ultrasonic Motor (TWUM) is a compact, precise, and silent actuator generating high torque at low speed without gears. Moreover, the TWUM has a high holding torque without supply, which makes this motor as an attractive solution for holding position of robotic arms. However, their nonlinear dynamics, and the presence of load-dependent dead zones often limit their use. Those issues can be overcome in closed loop with effective and precise controllers. In this paper, robust H-infinity (H∞) and discrete time RST position controllers are presented. The H∞ controller is designed in continuous time with additional weighting filters to ensure the robustness in the case of uncertain motor model and external disturbances. Robust RST controller based on the pole placement method is also designed and compared to the H∞. Simulink model of TWUM is used to validate the stability and the robustness of the two proposed controllers.

Keywords: piezoelectric motors, position control, H∞, RST, stability criteria, robustness

Procedia PDF Downloads 169
378 Research on Placement Method of the Magnetic Flux Leakage Sensor Based on Online Detection of the Transformer Winding Deformation

Authors: Wei Zheng, Mao Ji, Zhe Hou, Meng Huang, Bo Qi

Abstract:

The transformer is the key equipment of the power system. Winding deformation is one of the main transformer defects, and timely and effective detection of the transformer winding deformation can ensure the safe and stable operation of the transformer to the maximum extent. When winding deformation occurs, the size, shape and spatial position of the winding will change, which directly leads to the change of magnetic flux leakage distribution. Therefore, it is promising to study the online detection method of the transformer winding deformation based on magnetic flux leakage characteristics, in which the key step is to study the optimal placement method of magnetic flux leakage sensors inside the transformer. In this paper, a simulation model of the transformer winding deformation is established to obtain the internal magnetic flux leakage distribution of the transformer under normal operation and different winding deformation conditions, and the law of change of magnetic flux leakage distribution due to winding deformation is analyzed. The results show that different winding deformation leads to different characteristics of the magnetic flux leakage distribution. On this basis, an optimized placement of magnetic flux leakage sensors inside the transformer is proposed to provide a basis for the online detection method of transformer winding deformation based on the magnetic flux leakage characteristics.

Keywords: magnetic flux leakage, sensor placement method, transformer, winding deformation

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377 A Method for Precise Vertical Position of the Implant When Using Computerized Surgical Guides and Bone Reduction

Authors: Abraham Finkelman

Abstract:

Computerized Surgical Guides have been proven to be a predictable way to perform dental implants, with a relatively high accuracy in comparison to a treatment plan. When using the CSG Bone supported, it allows us to make the necessary changes of the hard tissue prior to the implant placement and after the implant placement. The CSG gives us an accurate position for the drilling, and during the implant placement it allows us to alter the vertical position of the implant altering the final position of the abutment and avoiding any risk of any damage to the adjacent anatomical structures. Any Changes required to the bone level can be done prior to the fixation of the CSG using a reduction guide, which incur extra surgical fees and the need of a second surgical guide. Any changes of the bone level after the implant placement are at the risk of damaging the implant neck surface. The technique consists of a universal system that allows us to remove the excess bone around the implant sockets prior to the implant placement which then enables us to place the implant in the vertical position with accuracy as planned with the CSG. The systems consist of a hollow pin of different sizes and diameters. Depending on the implant system that we are using. Length sizes are from 6mm-16mm and a diameter of 2.6mm-4.8mm. Upon the completion of the drilling, the pin is then inserted into the implant socket-using the insertion tool. Once the insertion tool has unscrewed the pin, we can continue with the bone reduction. The bone reduction can be done using conventional methods upon the removal of all the excess bone around the pin. The insertion tool is then screwed into the pin and the pin is then removed. We now, have the new bone level at the crest of the implant socket which is our mark for the vertical position of the implant. In some cases, when we are locating the implant very close to anatomical structures, any form of deviation to the vertical position of the implant during the surgery, can cause damage to such anatomical structures, creating irreversible damages such as paresthesia or dysesthesia of the mandibular nerve. If we are planning for immediate loading and we have done our temporary restauration in base of our computerized plan, deviation in the vertical position of the implant will affect the position of the abutment, affecting the accuracy of the temporary prosthesis, extending the working time till we adapt the prosthesis to the new position.

Keywords: bone reduction, computer aided navigation, dental implant placement, surgical guides

Procedia PDF Downloads 274