This paper presents a new method for the realtime estimation of the parameters and fluxes of induction motors.Such a procedure is useful for the design of self-commissioning drives, i.e., drives that can adjust controller parameters automatically for a wide range of motors and loads. Another potential application is for the diagnostic of failures. In their recursive form, the algorithms can be used for adaptation to parameters that vary with time, and for estimation of the rotor fluxes in a field-oriented controlled drive.The estimation method is based on a standard model of the induction motor, expressed in rotor coordinates. It is assumed that current and position (or velocity) measurements are available. The rotor fluxes are not assumed to be measured. The interesting features of the method are that: 1) it does not rely on special tests such as the locked rotor test or the no-load test (instead, a broad range of motor responses can be used), 2) the method provides estimates of the rotor fluxes together with the estimates of the parameters, 3) measures of the uncertainties in the estimated motor parameters are provided (this provides feedback as to the precision of the parameter estimates, as well as some guidance to choose excitation and to optimize the quality of the parameter estimation). Results for both simulated and experimental data are provided. Induction Motor Model S t a n d a r d Model Of t h e Induction MotorSt.andard models of induction machines are available in the literature. See [4] for example, where a model suitable for cont.rol applicat,ions is discussed. Parasitic effects such as hysteresis, eddy currents, magnetic saturation, and others are generally ne-

Despite planning college, disadvantaged students are less likely to enroll in college, particularly 4-year colleges. Beyond cost and academic achievement, previous research finds that a lack of college-related social resources poses barriers. However, little research investigates whether schools can help. We examine whether, how, and for whom a new counseling model aimed at providing college-related social resources may improve college enrollment. Following nearly all seniors in Chicago Public Schools from senior year through the fall after high school, we find that coaches may improve the types of colleges that students attend by getting students to complete key actions. It is important that the most disadvantaged students appear to benefit. This research suggests that targeting social resources may improve the high-school-to-college transition for disadvantaged students.

No abstract

Background College attendance has become a crucial determinant of life chances in U.S. society. Besides college costs and academic preparation, college-related cultural and social capital may help explain socioeconomic differences in whether and where students attend college. While high school counselors are seen as potential agents of social capital, the standard counseling model, developed to serve middle-class students, may not translate effectively to schools serving disadvantaged students. The college coach program, introduced in 12 non-selective Chicago Public Schools (CPS) in the fall of 2004, provides an alternative model. In contrast to the standard high school counseling model, college coaches take a “community organizer” role in assisting the college enrollment process. Statistical difference-in-differences analysis suggests that coaches may have improved the kinds of colleges that students attended, particularly for less advantaged students (Stephan, 2010). Purpose This qualitative study describes how the coach program works and analyzes key aspects that may explain its positive relationship with college enrollment outcomes. Participants Interviews were conducted between the spring of 2006 and spring of 2007 with 9 current and former college coaches, 2 postsecondary specialists (to whom the coaches report), and 30 high school seniors in 2 coach schools, which, like other non-selective CPS high schools, serve students who are predominantly African American or Latino and low-income. Research Design Responses to semi-structured interviews with coaches and students were coded for recurring themes and according to interview questions. A model of how coaches create social capital emerged from iterations between coding interviews and studying previous research on the creation of social capital. Conclusions The results suggest that coaches use new advising strategies (different from typical school counseling practices) to increase students’ college-related social capital and subsequently increase the number of students completing college actions, which may explain improved enrollment outcomes. This research highlights previously tacit assumptions about how counseling should work and details new advising procedures that may benefit disad-vantaged students in the college enrollment process. More generally, this research discusses specific social mechanisms through which policy or institutions may create social capital to improve educational attainment.

No abstract