Stochastic Particle Acceleration in Parallel Relativistic Shocks

We present results of test-particle simulations on both the first- and the second-order Fermi acceleration for relativistic parallel shock waves. Our studies suggest that the role of the second-order mechanism in the turbulent downstream of a relativistic shock may have been underestimated in the past, and that the stochastic mechanism may have significant effects on the form of the particle spectra and its time evolution.Comment: Poster at "The XXII Texas Symposium on Relativistic Astrophysics", Stanford, USA, December 2004, (TSRA04), 6 pages, LaTeX, 5 ps/eps figure

Distributed representation of multi-sense words: A loss-driven approach

Word2Vec's Skip Gram model is the current state-of-the-art approach for estimating the distributed representation of words. However, it assumes a single vector per word, which is not well-suited for representing words that have multiple senses. This work presents LDMI, a new model for estimating distributional representations of words. LDMI relies on the idea that, if a word carries multiple senses, then having a different representation for each of its senses should lead to a lower loss associated with predicting its co-occurring words, as opposed to the case when a single vector representation is used for all the senses. After identifying the multi-sense words, LDMI clusters the occurrences of these words to assign a sense to each occurrence. Experiments on the contextual word similarity task show that LDMI leads to better performance than competing approaches.Comment: PAKDD 2018 Best paper award runner-u

Why is solar cycle 24 an inefficient producer of high-energy particle events?

The aim of the study is to investigate the reason for the low productivity of high-energy SEPs in the present solar cycle. We employ scaling laws derived from diffusive shock acceleration theory and simulation studies including proton-generated upstream Alfv\'en waves to find out how the changes observed in the long-term average properties of the erupting and ambient coronal and/or solar wind plasma would affect the ability of shocks to accelerate particles to the highest energies. Provided that self-generated turbulence dominates particle transport around coronal shocks, it is found that the most crucial factors controlling the diffusive shock acceleration process are the number density of seed particles and the plasma density of the ambient medium. Assuming that suprathermal populations provide a fraction of the particles injected to shock acceleration in the corona, we show that the lack of most energetic particle events as well as the lack of low charge-to-mass ratio ion species in the present cycle can be understood as a result of the reduction of average coronal plasma and suprathermal densities in the present cycle over the previous one

The X-ray spectrum of Fe XVII revisited with a multi-ion model

The theoretical intensities of the soft X-ray Fe XVII lines arising from 2l-3l' transitions are reexamined using a three-ion collisional-radiative model that includes the contributions to line formation of radiative recombination (RR), dielectronic recombination (DR), resonant excitation (RE), and inner-shell collisional ionization (CI), in addition to the usual contribution of collisional excitation (CE). These additional processes enhance mostly the 2p-3s lines and not the 2p-3d lines. Under coronal equilibrium conditions, in the electron temperature range of 400 to 600 eV where the Fe XVII line emissivities peak, the combined effect of the additional processes is to enhance the 2p-3s lines at 16.78, 17.05, and 17.10 A, by ~ 25%, 30%, and 55%, respectively, compared with their traditional, single-ion CE values. The weak 2p-3d line at 15.45 A is also enhanced by up to 20%, while the other 2p-3d lines are almost unaffected. The effects of DR and RE are found to be dominant in this temperature range (400 - 600 eV), while that of CI is 3% at the most, and the contribution of RR is less than 1%. At lower temperatures, where the Fe XVII / Fe XVIII abundance ratio is high, the RE effect dominates. However, as the temperature rises and the Fe XVIII abundance increases, the DR effect takes over. The newly calculated line powers can reproduce most of the often observed high values of the (I17.05 + I17.10) / I15.01 intensity ratio. The importance of ionization and recombination processes to the line strengths also helps to explain why laboratory measurements in which CE is essentially the sole mechanism agree well with single-ion calculations, but do not reproduce the astrophysically observed ratios.Comment: Submitted to Ap

Continuous Improvement in the Assessment Process of Engineering Programs

In this paper, we present a multifaceted assessment process that was developed for our Electrical Engineering (EE) program at Georgia Southern University to meet the ABET criteria dealing with the student learning outcomes (SLOs). Both direct and indirect measures were used to collect and analyze data to assess the attainments of the student learning outcomes. To ensure data integrity, multiple faculty were involved in the development of a set of rubrics with benchmarks and performance indicators at both the program and curriculum levels. These tools provided action plans for this continuous improvement process to be implemented during the academic year. We also describe the mechanism used for assessing student performance at the curriculum level including the use of a course-level outcomes (CLO) form, a continuous improvement efforts (CIE) form, and a student course evaluation (SCE) form. These standardized forms are usually completed by faculty and submitted to the assessment committee for evaluation at the end of the semester. This feedback helped faculty to modify and/or develop new instructional methods to be incorporated into their courses, thus resulting in a more efficient assessment and continuous improvement process

A Unified Approach to the Assessment of Student Learning Outcomes in Electrical Engineering Programs

In this paper, a unified approach to the assessment of student and program learning outcomes to satisfy ABET and SACS accreditations criteria is proposed. This new approach takes into consideration the criteria of both accreditations to streamline the assessment process. As a result, a set of six skills categories were developed for SACS in which the eleven ABET student learning outcomes were embedded to satisfy both accreditation criteria. Furthermore, a standardized set of artifacts and rubrics were also developed to measure each skill category based on a given set of performance indicators. Data collected at the sophomore, junior and senior levels were recorded using a unified set of tables showing all the pertinent information needed to perform standard statistical analysis and to generate graphical presentation of the student performance at each level. For every outcome not meeting its benchmark, action plans were devised to address the shortcomings and close the loop on the assessment process. This novel approach was pilot tested this year for SACS and ABETS accreditations and has proved to be simpler and more efficient than any other assessment methods used

Learning Computational Thinking Using Open-Source Hardware-based Programming

Presentation given at the STEM Teaching and Learning Conference 2017, Savannah, GA

Gaming Against Plagiarism (GAP): A Game-Based Approach to Illustrate Research Misconduct to Undergraduate Engineering Students

In this paper, we discuss our experience using a set of games called Gaming Against Plagiarism to increase awareness in different types of research misconduct, and highlight the ramification of committing such misconducts among undergraduate engineering students. Gaming Against Plagiarism consists of three mini-games that address research misconduct. The types of research misconduct addressed are stealing, misquoting, patchwriting, insufficient paraphrasing, self-plagiarism, data falsification, and data fabrication. In these games, students are virtually put into situations involving research misconduct. The students either have to identify the type of misconduct or make an ethical decision by avoiding research misconduct. We assessed the impact of these games using qualitative and quantitative assessments techniques. Pre and post-surveys were conducted asking students to identity different research misconduct cases before and after they played the games. The results indicated that using this game-based approach to increase awareness of research misconduct among undergraduate students is effective. This conclusion was inferred by the statistical analysis with 98.7% confidence level. We also showed that the concepts of falsification and fabrication are somewhat confusing for students

Cross Disciplinary Perceptions of the Computational Thinking among Freshmen Engineering Students

In this paper, we analyzed the perception of Computational Thinking among engineering students from three engineering disciplines (Electrical, Mechanical, and Civil) and correlated their performance with their discipline. The goal of this analysis is to determine whether structuring discipline-specific Computational Thinking courses can improve the retention or having a diverse group of students in this course is more beneficial by allowing multidisciplinary interaction. This analysis was quantitatively verified by assessing the students\u27 performance in over 40 different sections of Computing for Engineers course taught from Fall 2012 to Spring 2014. Our sample consisted of 861 students (142 Civil, 484 Mechanical, and 235 Electrical). Students’ performance was assessed using quizzes, assignments, lab projects, and exams. We statistically analyzed students\u27 performance in this multi-section course to draw our conclusions which can help structuring Computational Thinking courses for engineering students from different engineering disciplines

Adaptive Teaching: An Effective Approach for Learner-Centric Classrooms

Adaptive Teaching: An Effective Approach for Learner-Centered Classrooms ABSTRACTWith the recent focus on student achievement, teachers are striving to improve the quality oftheir instruction methods to achieve a learner-centered environment in their classrooms. Thedifference in the students’ level of achievement in any specific course is mainly due to thedifference in the students’ aptitude for learning “Learning Style”. Unfortunately, the statictraditional teaching style “Chalk-&-Talk” which is still being used in engineering schools doesnot adapt to the changes in the cognitive profile of the student cohorts which reflects negativelyon the students’ achievement and performance, especially in engineering.In this paper, we discuss our approach on how to achieve adaptive teaching which leads to amore efficient learner-centered environment. Based on the Felder and Silverman index oflearning styles, there are four dimensions for the aptitude for learning which are active/reflectivelearners, sensing/intuitive learners, visual/verbal learners, and sequential/global learners. Thedifferent conglomeration of these dimensions for the students in any cohort form a specificcognitive profile. We used the Felder and Silverman index of learning styles survey to determinethe dominant learning styles within a cohort of students. Knowing the students’ cognitive profilehelped us adapt our teaching styles to achieve an optimal learner-centered classroom. We mainlyfocused on activities that would engage the majority of the students, to help facilitate the learningprocess and consequently, improve the students’ achievement. The effectiveness of this approachwas qualitatively and quantitatively verified by assessing the students’ performance usingtraditional teaching activities and activities tailored towards the students’ learning styles