A Flexible DSTATCOM Operating in Voltage or Current Control Mode

The topology and control are discussed of a distribution static compensator (DSTATCOM) that can be operated flexibly in the voltage or current control mode. In the voltage control mode, the DSTATCOM can force the voltage of a distribution bus to be balanced sinusoids. In the current control mode, it can cancel distortion caused by the load, such that current drawn by the compensated load is pure balanced sinusoid. Both these objectives are achieved, irrespective of unbalance and harmonic distortions in load currents or source voltages. The chosen DSTATCOM topology includes three single-phase voltage source inverters connected in parallel to a filter-capacitor, which allows the high-frequency component of the current to pass. A switching control scheme is proposed, and its suitability is proved for this problem. The proposed scheme is verified using computer simulation studie

Passing on Success? Productivity Outcomes for Quarterbacks Chosen in the 1999-2004 National Football League Player Entry Drafts

Seventy quarterbacks were selected during six NFL drafts held 1999-2004. This paper analyzes information available prior to the draft (college, college passing statistics, NFL Combine data) and draft outcomes (overall number picked and signing bonus). Also analyzed for these players are measures of NFL playing opportunity (games played, games started, pass attempts) and measures of productivity (Pro Bowls made, passer rating, DVOA, and DPAR) for up to the first seven years of each drafted player’s NFL career. We find that more highly-drafted QBs get significantly more opportunity to play in the NFL. However, we find no evidence that more highly-drafted QBs become more productive passers than lower-drafted QBs that see substantial playing time. Furthermore, QBs with more pass attempts in their final year of more highly-ranked college programs exhibit lower NFL passing productivity.Sports, NFL, Draft, Quarterback, Productivity

Superstars and Journeymen: An Analysis of National Football Team’s Allocation of the Salary Cap across Rosters, 2000-2005

The National Football League constrains teams’ payrolls via a “salary cap.” We analyze how teams allocate cap spending across rosters using a data set of over 10,000 player-season observations during 2000-2005. We find that a few players account for relatively high portions of teams’ caps, and that the players’ “cap values” are consistent with both “superstar” and Yule-Simon income distributions. A theoretical model based on a utility function convex with respect to winning is used to explain this result. We also find that the cap has been substantially effective in reducing teams’ ability to “spend their way to championships.”Sports, NFL, Draft, Quarterback, Productivity

Quantifying critical thinking: Development and validation of the Physics Lab Inventory of Critical thinking (PLIC)

Introductory physics lab instruction is undergoing a transformation, with increasing emphasis on developing experimentation and critical thinking skills. These changes present a need for standardized assessment instruments to determine the degree to which students develop these skills through instructional labs. In this article, we present the development and validation of the Physics Lab Inventory of Critical thinking (PLIC). We define critical thinking as the ability to use data and evidence to decide what to trust and what to do. The PLIC is a 10-question, closed-response assessment that probes student critical thinking skills in the context of physics experimentation. Using interviews and data from 5584 students at 29 institutions, we demonstrate, through qualitative and quantitative means, the validity and reliability of the instrument at measuring student critical thinking skills. This establishes a valuable new assessment instrument for instructional labs.Comment: 16 pages, 4 figure

Uncovering CDM halo substructure with tidal streams

Models for the formation and growth of structure in a cold dark matter dominated universe predict that galaxy halos should contain significant substructure. Studies of the Milky Way, however, have yet to identify the expected few hundred sub-halos with masses greater than about 10^6 Msun. Here we propose a test for the presence of sub-halos in the halos of galaxies. We show that the structure of the tidal tails of ancient globular clusters is very sensitive to heating by repeated close encounters with the massive dark sub-halos. We discuss the detection of such an effect in the context of the next generation of astrometric missions, and conclude that it should be easily detectable with the GAIA dataset. The finding of a single extended cold stellar stream from a globular cluster would support alternative theories, such as self-interacting dark matter, that give rise to smoother halos.Comment: 7 pages, 7 figures, submitted to MNRA

Capacitive pressure transducer system

Closed loop capacitive pressure transducer with extended frequency response for very low pressure measurement

Where History Meets Pilgrimage: the Graves of Sheikh Yusuf Al-maqassari and Prince Dipanagara in Madura

This paper focuses on two pilgrimage sites in eastern Madura, the supposed graves of Sheikh Yusuf Al-Maqassari and Prince Dipanagara. It contrasts the scholarly history of these two figures with the stories that have grown up around them in eastern Madura. The Madurese stories of the two figures have shown remarkable resilience in the face of radically different stories that draw their authority from modern scholarship and Indonesian nationalism. The “true” burial places of the two figures are in the city of Makassar, but their “alternative” graves in Madura are sites of vibrant stories that give expression to local history, local story-telling conventions, local nationalist aspirations and the authority of Islam. The vitality of the alternative graves with their alternative origin stories raises several interesting questions about the connection between sites of religious importance and the construction of local identity and history