104 research outputs found
Fast Genetic Algorithm For Feature Selection — A Qualitative Approximation Approach
No full textWe propose a two-stage surrogate-assisted evolutionary approach to address the computational issues arising from using Genetic Algorithm (GA) for feature selection in a wrapper setting for large datasets. The proposed approach involves constructing a lightweight qualitative meta-model by sub-sampling data instances and then using this meta-model to carry out the feature selection task. We define "Approximation Usefulness" to capture the necessary conditions that allow the meta-model to lead the evolutionary computations to the correct maximum of the fitness function. Based on our procedure we create CHCQX a Qualitative approXimations variant of the GA-based algorithm CHC (Cross generational elitist selection, Heterogeneous recombination and Cataclysmic mutation). We show that CHCQX converges faster to feature subset solutions of significantly higher accuracy, particularly for large datasets with over 100K instances. We also demonstrate the applicability of our approach to Swarm Intelligence (SI), with results of PSOQX, a qualitative approximation adaptation of the Particle Swarm Optimization (PSO) method. A GitHub repository with the complete implementation is available2. This paper for the Hot-off-the-Press track at GECCO 2023 summarizes the original work published at [3].References[1] Mohammed Ghaith Altarabichi, Yuantao Fan, Sepideh Pashami, Peyman Sheikholharam Mashhadi, and Sławomir Nowaczyk. 2021. Extracting invariant features for predicting state of health of batteries in hybrid energy buses. In 2021 ieee 8th international conference on data science and advanced analytics (dsaa). IEEE, 1–6.[2] Mohammed Ghaith Altarabichi, Sławomir Nowaczyk, Sepideh Pashami, and Peyman Sheikholharam Mashhadi. 2021. Surrogate-assisted genetic algorithm for wrapper feature selection. In 2021 IEEE Congress on Evolutionary Computation (CEC). IEEE, 776–785.[3] Mohammed Ghaith Altarabichi, Sławomir Nowaczyk, Sepideh Pashami, and Peyman Sheikholharam Mashhadi. 2023. Fast Genetic Algorithm for feature selection—A qualitative approximation approach. Expert systems with applications 211 (2023), 118528.© 2023 Copyright held by the owner/author(s).</p
Spaces of contestation: the everyday experiences of ten African migrants in Cape Town
No full textIncludes bibliographical references.Xenophobia in South Africa is so overt that it has take a covert form. The 'xenocide' events that took place in 2008 were called xenophobic acts. It is the recurrent denialism of xenophobia on an everyday basis that this project has explored through the narrative accounts of ten African migrants in Cape Town. The lived everyday experiences of ten African migrants have brought forward the central argument of this thesis. From the data, it is evident that as a reponse to everyday pressures of prejudices and xenophobia in social and physical spaces, African migrants have developed mutable, unsettled and vagrant identities in order to cope with everyday low level violence. This argument emerged as four key stressors have been identified as the components of a more substantial explanation of xenophobia in South Africa. The four key components are: the enforcement of identity (national and group), the demarcation of spaces of belonging, the experiences of economic insecurity, and lastly a 'culture of violence' in South Africa. This thesis argues that these four stressors are the result of an on-going active process of xenophobic attitudes
The Role of Cultural Capital Sports Oriented on Workers’ Participation in the Newspaper in Tehran, Iran
No full textAbstract This study examined the role of cultural capital sport oriented on workers' participation. The active presence of workers in different workplaces is very significant; additionally, consider their physical health is so imperative. Moreover, distinguishing the effective factors that can increase the amount of workers’ physical health and persuade them to exercise is essential; also, lack of attention to them leads to several difficulties. In the study, focused on 400 workers who worked fo r the newspaper in Tehran, Iran. One questionnaire for assessing demographic factors and cultural capital sport oriented were used. Findings of the study showed that  cultural capital sport oriented have significant relationship with workers’ participation. Also, body image determined as the first reason for sport among workers. In overall, the sport has a noticeable role in workers’ life and it can grow their mind and body health. In this regard, the head of workers should be developed some methods for introducing workers to the sport; likewise, determined valuable programs for them to increase physical power and growing muscles.  Keyword: Cultural Capital, Physical Education, Sport, Workers’ Â
Effects of Teacher Response on Learners’ Writing Development, Ideal L2 Writing Self, and Writing Engagement
No full textResearch on responding to students’ writing in the second language (L2) domain has grown enormously over the past twenty years and has expanded to include studies that examine how teacher responses affect language learners’ affective states. Following this line of research, the current study investigated the effect of different types of teacher response on L2 learners’ writing development as well as their ideal L2 writing self (IL2WS) and writing engagement. A total of 103 intermediate students of four intact classes were recruited, each receiving either feedback, feedforward, feedback and feedforward, or no response. Participants received their respective responses on five writing assignments, completed the IL2WS questionnaire and Writing Engagement Scale, and wrote two assignments as pretest and posttest. Data analysis indicated that all three experimental groups developed their writing proficiency from pretest to posttest. It was found that the Feedback+Feedforward group performed significantly better than all other groups, and the Feedback and Feedforward groups could outperform the Control group but not each other. Moreover, the results showed that groups receiving feedforward alone and in combination with feedback improved in terms of IL2WS and engagement. These results imply teachers should be familiarized with the concept of feedforward and encouraged to employ feedforward in tandem with feedback to help learners make greater learning gains
Sublinear algorithms for massive data problems
No full textThesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 227-244).In this thesis, we present algorithms and prove lower bounds for fundamental computational problems in the models that address massive data sets. The models include streaming algorithms, sublinear time algorithms, property testing algorithms, sublinear query time algorithms with preprocessing, or computing small summaries for large data. More precisely, we study the following problems. The (Approximate) Nearest Neighbor problem models the task of searching among a large data set of objects. Given a data set of n points in a high dimensional space, its goal is to search for the closest point in the data set to a given query point, in sublinear time, and by suitably preprocessing the data. This problem has numerous applications in image and video databases, information retrieval, clustering, and many others. In these applications, the points model the objects in a large data set, and their closeness measure similarity between the objects. However, for the purpose of many applications, the basic formulation of Nearest Neighbor as described, encounters several challenges which we address in this thesis: we show how to deal with the case where the data is corrupted or incomplete, how to handle multiple related queries, and how to handle a data set of more complex objects rather than simple points. Next, we show a general approach for solving massive data problems. We introduce the notion of Composable Coresets, defined as small summaries of multiple data sets that can be aggregated together to summarize the whole data. We show how to compute such summaries for several clustering problems, and at the same time, demonstrate that no such summaries are possible for other natural problems such as maximum coverage. Finally, we study the Set Cover problem in alternate sublinear models: streaming algorithms (where one makes a small number of passes over the data using small storage), and sublinear time algorithms (where one computes the answer without reading the whole input). We present tight approximation algorithms for the Set Cover problem in both of these models. In this thesis, we introduce theoretical problems and concepts that model computational issues arising in databases, computer vision and other areas. Most of the presented algorithms are simple and practical to implement.by Sepideh Mahabadi.Ph. D
Feature engineering for microstructure-property mapping in organic photovoltaics
No full textLinking the highly complex morphology of organic photovoltaic (OPV) thin films to their charge transport properties is critical for achieving high performance material system that serves as a cost-efficient approach for energy harvesting. In this paper, a novel unsupervised feature engineering framework is developed and used to establish reduced-order structure-property linkages for OPV films. This framework takes advantage of digital image processing algorithms to identify the salient material features of OPVs undergoing the charge transport phenomenon. These material states are then used to obtain a low-dimensional representation of OPV microstructures via 2-point spatial correlations and principal component analysis. It is found that in addition to the material PC scores, two distance-based metrics are required to complete the microstructure quantification of complex OPVs. A localized version of the Gaussian process (laGP) is then used to link the material PC scores as well as the two distance-based metrics to the short-circuit current of OPVs. It is demonstrated that the unsupervised feature engineering framework presented in this paper in conjunction with the laGP can lead to high-fidelity and accurate data-driven structure-property linkages for OPV films.This is a pre-print of the article Hashemi, Sepideh, Baskar Ganapathysubramanian, Stephen Casey, Ji Su, and Surya R. Kalidindi. "Feature engineering for microstructure-property mapping in organic photovoltaics." arXiv preprint arXiv:2111.01897v1. (2021). Copyright 2021 The Author(s). CC BY-NC-ND 4.0. Posted with permission
Relationship between Social Identification and Sport Participation amongst Staff of Developmental and Maintenance of Sports in Iran
No full textSocial identification determined as one of the imperative factor that specialized one society from the another one. In fact, this factor has been impacted by various items such as sport participation and appears comprehensively. Sport participation has considerable influence on health of society and conducts individuals’ identification in different ways. In this regard, the present study focused on the relationship between social identification and sport participation amongst 270 staff who are working on developmental and maintenance of sports in Iran. The data has been got based on Social Identification (Safarnia, 1993), and Participation Motivation Questionnaire (PMQ; Gill et al., 1983). The results showed that the sport participation has meaningful relation with social identification. In reality, the staff who considered on team working as participation and supply this main factor on their daily life shown better social identification. Keywords: Social Identification, Sport Participation, Staff, Ira
Designing a locomotive device driven by a shape memory alloy composite: a mimicry of the caterpillar movement
No full textThe materials we encounter in our every day lives already extend beyond the traditional materials of wood, metal, ceramics and glass. The characteristics and behavior of materials and material composites are continuously being tweaked. The introduction of new materials that can respond to inputs from the environment has brought about a new movement for material development and interaction design: computational composites. A computational composite is capable of sensing inputs from the environment, processing and controlling the consequent expression or formation of the material.The aim of the thesis was two-fold: to design and develop a soft bodied mechanism inspired by the movement of a caterpillar, using a Shape Memory Alloy-based (SMAs) composite, and to design material concepts based on the qualities of the composite.This was an explorative project, investigating the application of a bio-inspired approach and the Material Driven Design (MDD) approach to the development of a moving material.The first phase of the project focused on uncovering the technical aspects of a SMA-based composites and its relation to a computational composite. To understand caterpillar locomotion, a thorough study on its anatomy and locomotion strategies was performed. A qualitative study on howdesigners interpret caterpillar-like motion lead to four interesting movements, which were further developed in moving SMA-based composites from silicone and 4D printed textile.One SMA-based composite was selected for further improvement of the mechanism to be capable of translational caterpillar-like motion.The mechanism can also be interpreted and applied in other ways, and thus the experiential characteristics of the material were uncovered to define a material experience vision for further applications. Through a creative session and ideation phase three material concepts were proposed, suited for three types of user input on the computational composite: none, indirect and direct.The ultimate purpose for the material would be to sensitize people to the idea of a world where materials move from passive objects to active elements in our daily lives. It is recommended to do more research on the composite and to apply the materials experience vision to applications beyond every day objects and into the more innovative field of computer interface design and human-material interaction.Integrated Product Desig
Designing a recyclable impact resistant tablet cover
No full textThis thesis looks into the application of self-reinforced polypropylene (SRPP) in a tablet cover for the company Gecko Covers. Gecko Covers is a company that provides protection for devices in the form of covers and sleeves. They are performing at their best in the tablet market. They would like to enter the impact resistant tablet cover market using an impact cover that is both impact resistant and stylish. Their product style is characterized by the usage of contrast in both material texture and color, simple shapes and an attention to detail. Based on a market analysis, the tablet user on the go is selected as target group. These people carry their tablets with them wherever they go. To differentiate from the current competitors in this tablet market segment, Gecko has to focus on reducing the environmental impact of the new cover by e.g. making it recyclable. The most important material properties for the impact cover are high toughness, low density and a minimum ductile-to-brittle temperature of -20 °C. Not only does SRPP meet these requirements, it is also recyclable as it is only made out of a single type of thermoplastic. The manufacturing process of producing laminates out of woven SRPP influences the material properties such as impact resistance. Literature research shows that a combination of hot compaction and film stacking improves the impact resistance of the SRPP laminate the most. The values of the other parameters which influence the material properties of the laminates were determined through trial and error. To evaluate the SRPP laminates, a bending fatigue test and an alternative Izod impact test were conducted. In the end, the laminates with a compaction temperature of 170 °C, a pressure of 1,73 bar, an active heating time of 5 min and 1 PP film layer in between the SRPP fiber layer are the toughest and ductile. The focus of the design was on a minimum viable product. A back structure inspired by those of suitcases, the screen edge and the regular corners and edges of the cover were all taken into account. To validate that the shape is manufacturable from SRPP, a proof of concept was made with a mold. Furthermore, this proof of concept was tested via a drop test to get more information about the actual performance of the SRPP layer and to determine which orientation would have the highest impact resistance. The drop test showed the importance of the screen edge, which was missing from the proof of concept as it cannot be made out of SRPP. The test also showed that the SRPP lacked damping. To add the screen edge and the damping to the product, additional injection molded PP was used in order to add the screen edge and damping elements to the product. The final design was inspired by natural Voronoi structures and also creates a contrast in material texture and color, matching the current style of Gecko Covers.Integrated Product Desig
Interface on the skin: Designing through a user centered approach
No full textSince technological devices become smaller and our devices are more fused with our bodies, the logical next step is that technology will be placeable on our skin. In this thesis the design process towards a useful application of an interface on the skin is described. To get towards this design, several methods are used in the process. To shape the design challenge, a VIP inspired method is used, which provides a clear design goal and domain. For further developing the design, a user-centered approach is used, where the use of small prototypes helps improve the design. This resulted in a tattoo-like interface on the skin, which enables the user to have more unexpected interactions with others around him. This has been designed as a counter product towards the trend of people turning towards their devices in public situations. This tattoo offers a way of increasing real social interaction, and therefore decreases the social need of interaction through our smart devices. The design can be customly build up to fit the corresponding context, which makes it applicable in many social situations where people might have the need for more social interactions.Design for Interactio
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