Low cost instrumentation amplifier

Amplifier can be used for many applications requiring high input impedance and common mode rejection, low drift, and gain accuracy on order of one percent. Performance of inexpensive amplifier approaches that of some commercial instrumentation amplifiers in many specifications

Multiple Approaches to Absenteeism Analysis

Absenteeism research has often been criticized for using inappropriate analysis. Characteristics of absence data, notably that it is usually truncated and skewed, violate assumptions of OLS regression; however, OLS and correlation analysis remain the dominant models of absenteeism research. This piece compares eight models that may be appropriate for analyzing absence data. Specifically, this piece discusses and uses OLS regression, OLS regression with a transformed dependent variable, the Tobit model, Poisson regression, Overdispersed Poisson regression, the Negative Binomial model, Ordinal Logistic regression, and the Ordinal Probit model. A simulation methodology is employed to determine the extent to which each model is likely to produce false positives. Simulations vary with respect to the shape of the dependent variable\u27s distribution, sample size, and the shape of the independent variables\u27 distributions. Actual data,based on a sample of 195 manufacturing employees, is used to illustrate how these models might be used to analyze a real data set. Results from the simulation suggest that, despite methodological expectations, OLS regression does not produce significantly more false positives than expected at various alpha levels. However, the Tobit and Poisson models are often shown to yield too many false positives. A number of other models yield less than the expected number of false positives, thus suggesting that they may serve well as conservative hypothesis tests

Development and design of three monitoring instruments for spacecraft charging

A set of instruments which provide early detection of potentially dangerous geomagnetic substorm conditions and monitor the spacecraft response are discussed. The set consists of a sensor that measures the characteristic energy of collected electrons or ions from + 100 to - 20,000 V, a logarithmic current density sensor that measures local electron flux and a transient events counter that counts the spurious pulses from electrostatic discharges that couple into the spacecraft wiring harness. Design details and performance characteristics of the three instruments are given. Size, weight, and power requirements are minimized

The Relative Effects of Merit Pay, Bonuses, and Long-Term Incentives on Future Job Performance (CRI 2009-009)

Extant compensation literature has indicated that pay-for-performance can influence employee performance. There is little research, however, that differentiates the effects of certain forms of pay-for-performance plans on future performance. By applying the precepts of expectancy theory to specific components of the pay-for-performance plans and using longitudinal data from a sample of 739 US employees in a service-related organization, this study demonstrates different effects for merit pay, bonuses, and long-term incentives

Validation of Expert Systems: Personal Choice Expert -- A Flexible Employee Benefit System

A method for validating expert systems, based on psychological validation literature and Turing\u27s imitation game, is applied to a flexible benefits expert system. Expert system validation entails determining if a difference exists between expert and novice decisions (construct validity), if the system uses the same inputs and processes to make its decisions as experts (content validity), and if the system produces the same results as experts (criterionrelated validity). If these criteria are satisfied, then the system is indistinguishable from experts for its domain and satisfies Turing\u27s imitation game. The methods developed in this paper are applied to a human resource expert system, Personal Choice Expert (PCE), designed to help employees choose a benefits package in a flexible benefits system. Expert and novice recommendations are compared to those generated by PCE. PCE\u27s recommendations do not significantly differ from those given by experts. High inter-expert agreement exists for some benefit recommendations (e.g. Dental Care and Long-Term Disability) but not for others (e.g. Short-Term Disability and Life Insurance). Insights offered by this method are illustrated and examined

Utility Analysis for Multiple Selection Devices and Multiple Outcomes

Traditional utility analysis only calculates the value of a given selection procedure over random selection. This assumption is not only an inaccurate representation of staffing policy but leads to overestimates of a device\u27s value. This paper generates a new utility model that accounts for multiple selection devices and multiple criteria. The model is illustrated using previous utility analysis work and an actual case of secretarial employees with eight predictors and nine criteria. A final example also is provided which includes these advancements as well as other researchers\u27 advances in a combined utility model. Results reveal that accounting for multiple criteria and outcomes dramatically reduces the utility estimates of implementing new selection devices

Cycling chaotic attractors in two models for dynamics with invariant subspaces

Nonergodic attractors can robustly appear in symmetric systems as structurally stable cycles between saddle-type invariant sets. These saddles may be chaotic giving rise to 'cycling chaos'. The robustness of such attractors appears by virtue of the fact that the connections are robust within some invariant subspace. We consider two previously studied examples and examine these in detail for a number of effects: (i) presence of internal symmetries within the chaotic saddles, (ii) phase-resetting, where only a limited set of connecting trajectories between saddles are possible and (iii) multistability of periodic orbits near bifurcation to cycling attractors. The first model consists of three cyclically coupled Lorenz equations and was investigated first by Dellnitz et al. (1995). We show that one can find a 'false phase-resetting' effect here due to the presence of a skew product structure for the dynamics in an invariant subspace; we verify this by considering a more general bi-directional coupling. The presence of internal symmetries of the chaotic saddles means that the set of connections can never be clean in this system, that is, there will always be transversely repelling orbits within the saddles that are transversely attracting on average. Nonetheless we argue that 'anomalous connections' are rare. The second model we consider is an approximate return mapping near the stable manifold of a saddle in a cycling attractor from a magnetoconvection problem previously investigated by two of the authors. Near resonance, we show that the model genuinely is phase-resetting, and there are indeed stable periodic orbits of arbitrarily long period close to resonance, as previously conjectured. We examine the set of nearby periodic orbits in both parameter and phase space and show that their structure appears to be much more complicated than previously suspected. In particular, the basins of attraction of the periodic orbits appear to be pseudo-riddled in the terminology of Lai (2001)

Out-of-Pocket Costs and the Flexible Benefits Decision: Do Employees Make Effective Health Care Choices?

This study analyzes employees\u27 ability to select health insurance benefits that fit their needs.The study analyzes both the actual choices and the implications of those choices for employees, measured as out-of-pocket costs (OPC). By introducing OPC as a measure of decision quality, this study demonstrates its advantages over measuring only employee choice. Results from a sample of manufacturing employees suggest that most employees made cost-optimizing decisions, out-performing recommendations from a linear model. Employees also were financially better off overall with choice than they would have been had they all been placed into either medical plan option available to them. This study supports the value of choice, but does not support the assertion that employees always make benefits decisions that best fit their needs