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关键词： Clustering algorithms   Indexes   Machine learning algorithms   Complexity theory   Costs   Computer science   Task analysis   K-means   silhouette algorithm   clustering   central limit theorem   divide and conquer  

摘要： Clustering is one of the critical parts of machine learning algorithms. K-Means clustering is the standard technique that various data analysts use for clustering the data among the various clusters. Even though the K means clustering algorithm can work effectively, there is a need to tune the value of K according to the dataset under consideration. The process of tuning for the value of k requires the execution of the K-means algorithm with different values of k. The values of k with the best cluster quality based on specific metrics are selected. The elbow method and silhouette coefficient is the most popular approach for selecting the number of clusters. However, both approaches are time-consuming, as they have to execute K-means for each value of k to find a good score. This approach is iterative. This paper proposed a divide and conquer approach that performs the same task in less time. From the proposed approach, the task has been completely 2.5 times faster in comparison to the iterative method at the cost of some memory required to store the results.

关键词： Computer engineering   Design optimization   Photonics   Physics   Optimization algorithms   Computer science   Design   Engineering  

摘要： This thesis covers a number of results in heuristics for approximately solving photonic design problems and bounds for the optimal value of such problems. Chapter 2 begins the thesis with an overview of the literature and a very general introduction to the photonic design problem, along with simplified summaries of the usual techniques used in both approximately solving physical design problems and in computing bounds for the optimal value of these optimization problems. Chapter 3 shows a heuristic which can be used to find approximate solutions to the photonic design problem and discusses some interesting observations based on the ideas introduced. In chapter 4, we cover a particular technique for bounding the optimal value of photonic design problems, along with several generalizations. Finally, chapter 5 shows a generalization of a number of bounds available in the literature to include objectives that often show up in efficiency metrics.

摘要： For the past forty years, under-represented girls in computer science have been a worldwide issue. Research has indicated strategies and practices teachers can implement to help shape adolescent girls’ identity in computer science. These strategies include inclusive curricular practice, collaborative learning opportunities, and supportive learning environments. This study aimed to explore how a student’s computer science perception influenced their identity and how incorporating art into coding can shape their identity. Using qualitative data collection, the findings from this study were used to develop further a curriculum unit that can shift adolescent girls’ computer science identity. The following research questions were used for this study: How have the identity-based curricular interventions shifted my teaching? Over the course of the focal unit, how and to what extent do adolescent girls in the Applications (Apps) and Gaming course indicate a change in their computer science identities? This study aimed to determine if a computer science curriculum that incorporated art into coding can help develop adolescent girls’ identity in computer science. The study design incorporated an analysis of lesson plans, classroom observations, reflective open-ended questions, and teacher journals to determine an identity development in computer science for adolescent girls. The participants included five high-school aged girls from a Mid-Atlantic urban high school. Over the course of five weeks, the students participated in the study that including drawings of what a computer scientist looks like to them, open-ended reflective questions, and other various everyday classroom tasks. The drawings of the computer scientist and open-ended reflective questions were analyzed to determine a change in their computer science identity over the course of the five-week study. The findings from this study indicated a shift in identity for some participants and may also be interpreted as a

关键词： Receivers & amplifiers   Global positioning systems--GPS   Software   Time series   Orbits   Ground stations   Altitude   Artificial satellites   Aerospace engineering   Astronomy   Computer science   Electrical engineering   Engineering  

关键词： computer science   electrical engineering   hands-on   individual practice   senior students   telecommunication   undergraduate   white box testing  

摘要： Several studies have shown that the main challenge in teaching complex systems involving many theoretical backgrounds to senior students is their lack of confidence. In this paper, we present an approach to the teaching methodology of an undergraduate course in a telecommunication study program. The first goal of this methodology is to help students understand the theoretical concepts behind wireless digital communication systems through direct practice to give them more exposure to a real system through affordable practice activities in an experiential context, utilizing an HF radio and a single-board computer (SBC). The second goal is to challenge senior students to understand the data link layer by using white box testing of the syntax of the programming language embedded in the SBC. This approach is ideally carried out based on offline and hands-on class activities, however, the pandemic condition made it unavoidable to do it online using a demonstration model. Feedback from students was collected through written comments, post-testing, including a facility index analysis, and a questionnaire that was distributed using the available e-learning system. The post-test results showed that the average score was 72 out of a maximum of 100.

关键词： Physics   Ophthalmology   Optics   Medical imaging   Astronomy   Atomic physics   Computer science   Food Science   Mathematics   Mechanics   Medicine  

关键词： Bibliometrics   Databases   Computer science   Collaboration   Sustainable development   Standards   Social networking (online)   Bibliometric analysis   citation impact   collaboration structure   gender distribution   IEEE Access   thematic structure   sustainable development goals  

摘要： The IEEE Access journal started in 2013, and in a short period, it has attained recognition for being a preferred multidisciplinary journal, with characteristics of rapid and continuous publishing. It is now ranked among the top journals in Engineering and Computer Science (General) by Scopus. Recognizing the distinctive nature of the journal and its contributions in the broader area of Engineering and Computer Science, this article attempts to present a detailed bibliometric analysis of the journal to identify publishing patterns, authorship and collaboration structure, citation impact, funding patterns of the published research, and the thematic structure of the publication. The gender distribution is also computed to identify papers published by male and female authors. The social media visibility of the articles and the Sustainable Development Goals (SDG) connections of articles were also identified. The results indicate that the IA journal can attract novel, high-quality multidisciplinary research, which aligns with the relevant and the most pressing SDGs. Furthermore, the journal has experienced increased multi-authored multidisciplinary research, and it is publishing a more significant percentage of articles with female first authors.

关键词： Polymers   Nitrates   Software   Cameras   Gases   Cellulose   Ammunition   Carbon   Labeling   Copper   Design   Mouth   Geometry   Ballistics   Nitrogen   Computer science   Mathematics   Polymer chemistry  

摘要： Characterizing the behavior of highly unstable bodies in flight presents a variety of engineering challenges. Free-flight testing with scale models provides an efficient and economical solution to this problem. This test method requires a means of launching the test model, undamaged, at the desired velocity. The objective of this research was to develop a launch system which incorporates the use of energetic materials for free-flight testing of a model flight vehicle of predetermined mass and dimensions. A high-low pressure gun system was selected for the launcher design, as this system is capable of launching relatively high masses in the velocity range of interest while retaining the necessary reliability and repeatability for useful free-flight testing. This research effort covers the entire process of the design, development, and construction of a novel launch system that makes use of energetic materials for the launch propellant. The energetic material used in this research was double-base smokeless propellant. An analysis of the selected propellant was conducted to determine the relevant physical and chemical properties. These were used in the development of an internal ballistics model created in MATLAB. The purposes of this model were to inform the launcher design process and make predictive velocity estimates for future work. Propellant cartridges specific to this research and procedures for their production were developed and tested. High-speed cameras were utilized for the acquisition of velocity data and also proved useful in observing the dynamics of the launch event during iterations of the launcher design process. The launch system’s potential for use with other data acquisition methods were also investigated. These included infrared motion capture cameras and an in-chamber pressure transducer. The series of test launches conducted with the completed launcher achieved the required velocity for the given mass of the flight model and resulted in a mean

关键词： Cryptography   Encryption   Matrix Converters   Intelligent Systems   Computer Science   Time Complexity   Smart Buildings   Encryption   Decryption   Key Management   Clique   Intelligent And Smart Building  

摘要： Because encryption is a fundamental security building block, existing encryption techniques like AES, Twofish, Blowfish, and Triple DES are constantly under the threat of being compromised. We introduce a simple graph-theoretic encryption method named CryptoCliqIn using clique injection and prove that the decryption of this encryption without the appropriate key is #P-complete. We have shown that the proposed model does not introduce delays in encryption and decryption times and provides a more secure mechanism compared to some of the existing encryption mechanisms. Finally, an adaptation of CryptoCliqIn in an intelligent system is discussed under the setup of intelligent and smart building.

关键词： Engineering   Bioinformatics   Computer science   Genetics   Physics  

摘要： Clostridia organisms have a unique diversity in substrate utilization and metabolism that include CO2 fixation, lignocellulose consumption, and both acetogenic and solventogenic regimes that makes them useful as production platforms for a wide range of chemicals. Unlike model organisms, however the mechanistic determinants of phenotype are not well understood, presenting a challenge to their engineering and development for use in industrial fermentation processes. Kinetic models of metabolism are promising tools for studying Clostridia because they offer a means for not only predicting metabolic state in response to network perturbations, but also for elucidating mechanisms actively controlling metabolism. They are advantageous over purely stoichiometric models for these purposes because they capture the simultaneous and interrelated shift in metabolite concentration and metabolic flux in response to network perturbations. In Chapter 1, we present an overview of recent advances in the development of kinetic models of metabolism for application towards metabolic engineering. The ways in which key considerations made during network construction, formalism selection, and data curation steps influence predictive capability are first discussed. We then explore how accelerating kinetic parameterization can improve kinetic model applicability within design-build-test-learn cycles and expand the types of follow-up analysis that can be performed using large-scale kinetic models of metabolism. Finally, we explore how we can infer design targets through sensitivity analysis and provide an overview of the kinetic models that have been recently parameterized and deployed to aid in the rational design of microorganisms. Several hurdles to large-scale kinetic model parameterization exist, including data availability, computational expense, a lack of established best practices for parameterization and follow-up analysis. Although these challenges have been long recognized, a formal