The Application of the Econometric Models with Qualitative Variables in the Analysis of the Non Academic Behaviors at the Level of the Romanian Higher Education System

The purpose of this paper was to apply the econometric models with qualitative variables in order to analyze two non academic behaviors at the level of the Romanian higher education system: cheating on the exams by copying or by direct or intermediary intervention at the professor.Logit Model, survey, sample, fraud

Full-bridge MMC DC fault ride-through and STATCOM operation in multi-terminal HVDC grids

This paper investigates a control structure to enhance the DC fault ride-through capability of a full-bridge modular multilevel converter (MMC) station, while ensuring a stable controlled operation as a STATCOM during DC faults without the need for fault isolation. Taking advantage of the switching states of a full-bridge submodule, a DC current controller is proposed, which provides the DC voltage reference for the modulation when a DC fault is detected. By changing the outer controllers strategy from DC voltage or active power control to converter energy control during a fault, the decoupling of the converter operation from the DC side dynamics is realized. In this paper, the focus is on the control methodology at all times of operation and the evaluation of the STATCOM control during a fault. To this end, extensive simulations were performed on a three-terminal high voltage direct current (HVDC) grid in radial configuration and a pole-to-pole DC fault case was investigated. The results showed that the AC voltage and current were controlled within limits at all times, while the full-bridge MMC was able to provide reactive power support to the AC grid. Moreover, using the proposed control methodology, the transients at the operation transition points between STATCOM and inverter/rectifier operation were minimized and the stations were able to safely ride through the fault

Toward an Integrated Online Learning Environment

We are building in LON-CAPA an integrated learning environment that will enable the development, dissemination and evaluation of PER-based material. This environment features a collection of multi-level research-based homework sets organized by topic and cognitive complexity. These sets are associated with learning modules that contain very short exposition of the content supplemented by integrated open-access videos, worked examples, simulations, and tutorials (some from ANDES). To assess students' performance accurately with respect to a system-wide standard, we plan to implement Item Response Theory. Together with other PER assessments and purposeful solicitation of student feedback, this will allow us to measure and improve the efficacy of various research-based materials, while getting insights into teaching and learning.National Science Foundation (U.S.) (Grant 0757931)National Institutes of Health (U.S.) (Grant # 1RC1RR028302-01

Improved Student Performance In Electricity And Magnetism Following Prior MAPS Instruction In Mechanics

We examine the performance of a group of students in Introductory Electricity and Magnetism following a ReView course in Introductory Mechanics focusing on problem solving employing the Modeling Applied to Problem Solving (MAPS) pedagogy[1]. The group consists of students who received a D in the fall Mechanics course (8.01) and were given the chance to attend the ReView course and take a final retest. Improvement to a passing grade was qualification for the Electricity and Magnetism course (8.02) in the spring. The ReView course was conducted twice—during January 2009 and January 2010. As a control, we took a group of students with similar z-scores in 8.01 in Fall 2007 that were not offered the ReView course. We show that the ReView students perform ~0.7 standard deviations better than the control group (p~0.002) and ~0.5 standard deviations better than what is expected based on their performance in 8.01(p ~0.001).National Science Foundation (U.S.) (NSF grant # 0757931)National Institutes of Health (U.S.) (NIH grant # 1RC1RR028302-01

Planetary nebulae and stellar kinematics in the flattened elliptical galaxy NGC 1344

We present photometric and kinematic information obtained by measuring 197 planetary nebulae (PNs) discovered in the flattened Fornax elliptical galaxy NGC 1344 (also known as NGC 1340) with an on-band, off-band, grism + on-band filter technique. We build the PN luminosity function (PNLF) and use it to derive a distance modulus m-M=31.4, slightly smaller than, but in good agreement with, the surface brightness fluctuation distance. The PNLF also provides an estimate of the specific PN formation rate: 6x10^-12 PNs per year per solar luminosity. Combining the positional information from the on-band image with PN positions measured on the grism + on-band image, we can measure the radial velocities of 195 PNs, some of them distant more than 3 effective radii from the center of NGC 1344. We complement this data set with stellar kinematics derived from integrated spectra along the major and minor axes, and parallel to the major axis of NGC 1344. The line-of-sight velocity dispersion profile indicates the presence of a dark matter halo around this galaxy.Comment: 45 pages, 18 figures, accepted for publication in Ap

Semiclassical evolution of the spectral curve in the normal random matrix ensemble as Whitham hierarchy

We continue the analysis of the spectral curve of the normal random matrix ensemble, introduced in an earlier paper. Evolution of the full quantum curve is given in terms of compatibility equations of independent flows. The semiclassical limit of these flows is expressed through canonical differential forms of the spectral curve. We also prove that the semiclassical limit of the evolution equations is equivalent to Whitham hierarchy.Comment: 14 page

When students can choose easy, medium, or hard homework problems

We investigate student-chosen, multi-level homework in our Integrated Learning Environment for Mechanics [1] built using the LON-CAPA [2] open-source learning system. Multi-level refers to problems categorized as easy, medium, and hard. Problem levels were determined a priori based on the knowledge needed to solve them [3]. We analyze these problems using three measures: time-per-problem, LON-CAPA difficulty, and item difficulty measured by item response theory. Our analysis of student behavior in this environment suggests that time-per-problem is strongly dependent on problem category, unlike either score-based measures. We also found trends in student choice of problems, overall effort, and efficiency across the student population. Allowing students choice in problem solving seems to improve their motivation; 70% of students worked additional problems for which no credit was given.National Science Foundation (U.S.) (Grant PHY-0757931)National Science Foundation (U.S.) (Grant DUE-1044294