Primitive Parameters Research Articles

Experiment and Analysis of Combined Heat and Water Vapor Transfer Through Clothes with Condensation

A series of experiments is performed on the combined heat and water vapor transfer through fabric at simulated high altitudes. A considerable water vapor concentration difference is imposed between the water vapor source and the environment, so that condensation takes place in the specimen. A new analytical expression for the rate of condensation in textile materials is derived by considering the combined heat and mass transfer between the specimen and the environment. Although the amount of condensation in textiles can not be correlated well by primitive parameters such as temperature or water vapor concentration differences, good agreement can be obtained between the condensa tion mass flux measured experimentally and that calculated by means of the derived expression.

Minimum Wage Effects on Labor Market Outcomes Under Search with Bargaining

Building upon a continuous-time model of search with Nash bargaining in a stationary environment, we analyze the effect of changes in minimum wages on labor market outcomes and welfare. While minimum wage increases invariably lead to employment losses in our model, they may be welfare-improving to labor market participants using any one of a number of welfare criteria. A key determinant of the welfare impact of a minimum wage increase is the Nash bargaining power parameter. We discuss identification of this model using Current Population Survey data on accepted wages and unemployment durations, and demonstrate that key parameters are not identified when the distribution of match values belongs to a location-scale family. By incorporating a limited amount of information from the demand side of the market, we are able to obtain credible and precise estimates of all primitive parameters, including bargaining power. Direct estimates of the welfare impact of the minimum wage increase from $4.25 to $4.75 in 1996 provide limited evidence of a small improvement. Using estimates of the primitive parameters we show that more substantial welfare gains for labor market participants could have been obtained by doubling the minimum wage rate in 1996, though at the cost of a perhaps unacceptably high unemployment rate.

Automatic time-bound analysis for a higher-order language

Analysis of program running time is important for several applications, including reactive systems, interactive environments, compiler optimizations and performance evaluation. Automatic and efficient prediction of accurate time bounds is particularly important, and being able to do so for high-level languages is particularly desirable. This paper presents a general approach for automatic and accurate time-bound analysis for a functional high-level language, that combines methods and techniques studied in theory, languages, and systems. The approach consists of transformations for building time-bound functions in the presence of partially known input structures, symbolic evaluation of the time-bound function based on input parameters, optimizations to make the analysis efficient as well as accurate, and measurements of primitive parameters, all at the source-language level. To handle higher-order functions, special transformations are needed to build lambda expressions for computing running times, to optimize the construction of the time lambda expressions, and to optimize the symbolic evaluation. It took us several tries to obtain the simple and concise transformations for handling lambda expressions. We describe analysis and transformation algorithms and explain how they work. We have implemented this approach and performed a large number of experiments analyzing Scheme programs. The measured worst-case times are closely bounded by the calculated bounds. We describe our prototype system, ALPA, as well as the analysis and measurement results.

The core in an oligopoly market with indivisibility

This paper studies the core in an oligopoly market with indivisibility. It provides necessary and sufficient conditions for core existence in a general m-buyer n-seller market with indivisibility. When costs are dominated by opportunity costs (i.e., a firm's variable costs are sufficiently small), the core condition can be characterized by the primitive market parameters. In a 3-2 market with opportunity cost, the core is non-empty if and only if the larger seller's opportunity cost is either sufficiently large or sufficiently small.

The Multistage Service Facility Start-Up and Capacity Model

In service industries, operations are often split into the “front office” and the “back room.” The front office deals directly with customers, whereas the back room engages in manufacturing-like operations. While such an arrangement may enjoy many benefits including reduced customer participation and back room efficiency, it gives rise to the possibility of communication and coordination problems between the front office and the back room. To address such coordination problems, we work from one popular piece of case material in operations management, the National Cranberry Cooperative (NCC) case, and develop and analyze a service facility start-up and capacity model based on a finite-horizon, multistage queueing system. The model allows for general variability that can be either stationary or nonstationary, predictable or unpredictable. We derive the relationships between job start and finish times and primitive parameters and control variables using a sample path construction. We then show that two performance measures, the expected waiting and operating costs, have desirable convexity properties with respect to the control variables; namely, the starting time and the processing capacity of each stage. We also show how to perform marginal analysis on start-up times. Numerical examples based on the NCC case are presented and discussed. The model can be extended and applied to many service and manufacturing situations.

Prices as Aggregators of Private Information: Evidence from S&P 500 Futures Data

This paper assesses the importance of the role of prices as aggregators of private information in the S&P 500 futures market. We estimate primitive parameters of the Hellwig (1980) noisy rational expectations model, when both prices and terminal values are observable. The variance-covariance parameters governing futures prices and terminal values can be inverted to obtain estimates of the primitive parameters, including the precision of private information and the variance of liquidity motivated trades. We also estimate coefficients in the linear price conjecture, weights that agents place on different sources of information, and the informativeness of prices. We find that the variance of the error term in agents' private signals is several orders of magnitude larger than the variance of liquidity motivated trades. But in a large market prices are still so informative that the market as a whole appears to weight them more than prior beliefs.

Prices As Aggregators of Private Information: Evidence from the S&P 500 Futures Market

This paper assesses the importance of the role of prices as aggregators of private information in the S&P 500 futures market. We estimate primitive parameters of the Hellwig (1980) noisy rational expectations model, when both prices and terminal values are observable. The variance-covariance parameters governing futures prices and terminal values can be inverted to obtain estimates of the primitive parameters, including the precision of private information and the variance of liquidity motivated trades. We also estimate coefficients in the linear price conjecture, weights that agents place on different sources of information, and the informativeness of prices. We find that the variance of the error term in agents' private signals is several orders of magnitude larger than the variance of liquidity motivated trades. But in a large market prices are still so informative that the market as a whole appears to weight them more than prior beliefs.

An Autonomous Active Vision System for Complete and Accurate 3D Scene Reconstruction

We propose in this paper an active vision approach for performing the 3D reconstruction of static scenes. The perception-action cycles are handled at various levels: from the definition of perception strategies for scene exploration downto the automatic generation of camera motions using visual servoing. To perform the reconstruction, we use a structure from controlled motion method which allows an optimal estimation of geometrical primitive parameters. As this method is based on particular camera motions, perceptual strategies able to appropriately perform a succession of such individual primitive reconstructions are proposed in order to recover the complete spatial structure of the scene. Two algorithms are proposed to ensure the exploration of the scene. The former is an incremental reconstruction algorithm based on the use of a prediction/verification scheme managed using decision theory and Bayes nets. It allows the visual system to get a high level description of the observed part of the scene. The latter, based on the computation of new viewpoints ensures the complete reconstruction of the scene. Experiments carried out on a robotic cell have demonstrated the validity of our approach.

Thermogravimetry and Rietveld analysis for the high-temperature X-ray powder diffraction pattern of Y4Al2O9

Y4A1209 has a monoclinic crystal structure, space group P21/c [1]. The atomic parameters of this structure were refined by single crystal X-ray and neutron diffraction and by Rietveld analysis for the X-ray synchrotron powder diffraction pattern [2, 3]. Recently, we revealed the high-temperature phase transformation of Y4AIzO9 at 1377 °C by high-temperature differential scanning calorimetry (DSC), high-temperature dilatometry and hightemperature X-ray powder diffraction (XRD) [4, 5]. The low-temperature phase transformed to the high-temperature phase with a small change in endothermic enthalpy and small volume shrinkage. Thermal hysteresis and athermal phenomena were observed at this phase transition. Judging from these results, the phase transition was thought to be martensitic. Takizawa et al. reported a stress induced phase transition from a tetragonal structure to a monoclinic structure for (Hol_xLax)4Al209 and (Yl_xLax)4AlzO9 at room temperature [6]. In our previous study, peaks in the XRD of the high-temperature phase were indexed with a monoclinic cell [4]. However, the crystal structure of the high-temperature phase has not been clarified. This letter describes the thermogravimetric analysis of Y4AI209 and analysis of the crystal structure of the lowand high-temperature phases by the Rietveld method for XRD patterns obtained at room temperature, 1300 °C and 1400 °C. Y4A1209 was prepared from powders of Y203 (99.9% purity) and A1203 (99.9% purity). Stoichiometric amounts of powders were weighed and mixed in an agate mortar. The mixture was pressed into pellets and heated on a Pr 60%-Rh 40% plate in a molybdenum silicide furnace at 1600 °C for 10 h. The obtained pellets were powdered for thermogravimetry (TG) and XRD. TG was carried out with a high-temperature thermobalance (TG-DTA 2200, Mac Science). The rate of heating was 10 °Cmin -1. The XRD pattern was obtained at room temperature using CuKo~ radiation with a pyrolitic graphite monochromator and a diffractometer (RAD-C, Rigaku; tube voltage and current: 40kV and 20 mA). High-temperature XRD patterns were obtained with a graphite monochromator using a diffractometer with a high-temperature furnace attached (MXP18, Mac Science, tube voltage and current: 45 kV and 360 mA). The temperature was measured with a Pt-Rh13% thermocouple set into a Pt sample holder. Since the phase transition had the thermal hysteresis [4, 5], high-temperature XRD was performed at 1300 °C on heating and at 1400 °C on cooling f rom 1500 °C. The intensity data were collected from 10 to 70 ° in 20 with a sampling step width of 0.04 °. Rietveld analysis of the XRD data was carried out using the RIETAN program [7]. A weight loss of about 0.18% was detected for the powdered Y4A1209 sample from room temperature to 350 °C. This was probably due to detachment of adsorbed water. Above this temperature to 1500 °C, the weight change of the sample was less than 0.005%. This result indicated that oxygen atoms and other elements did not transfer from or into the sample within this weight range. Fig. 1 shows the profile fit and difference patterns of Rietveld analysis for the XRD data of Y4AI209 at room temperature, 1300 °C and 1400 °C. The solid lines are calculated intensity profiles and the dots crossing the profiles are observed intensities. The short vertical lines show the positions of possible Bragg reflections. The differences between observed and calculated intensities are plotted below the profiles. Table I lists the refined lattice p0rameters of the primitive monoclinic cells and R faqtors of the Rietveld analysis [8]. In the Rietveld refinement for the XRD pattern at room temperature, the calculated pattern fits the observed one well. The lattice parameters of the present study were almost equal to those reported by Lehmann et al. [2] for the a-axis and /3, and were slightly smaller than those for the band c-axes. The relative intensities of the main diffraction peaks of the high-temperature phase at 1400 °C were not so different from those of the low-temperature phase at room temperature and 1300 °C (Fig. 1). Since the peaks overlapped at higher Bragg angles, the relative intensities of the peaks at 20 from 10 to 25 ° were compared. For the high-temperature phase, peaks of 10 0 and i 12 became very small, and the relative intensities of 1 10 and i 02 were larger than those of the low-temperature phase. Based on the peaks of the powder diffraction pattern of the high-temperature phase, we were not able to adopt any space group except P21/c. Therefore, we analysed its crystal structure with the space group of P21/c. The lattice parameters of the face-centred cell are also listed in Table I; they were calculated from the refined primitive lattice parameters with the conversion proposed by Brandle and Steinfink [9]. The/3' angle of the face-centred cell was close to 90 ° but the lattice of the high-temperature phase did not become orthorhombic.

Sequential Labor Decisions Under Uncertainty: An Estimable Household Model of West-African Farmers

This paper reports estimates of the structural parameters of a stochastic control model that describcs the labor decisions of small farmers in Burkina Faso, West Africa. The focus of the estimation is on measuring flexibility in production and intertemporal substitutability in consumption. Full information maximum likelihood estimates of the primitive parameters of the model are computed even though optimal labor decision rules cannot be derived analytically. Vuong's non-nested model specification test shows that this method yields parameter estimates that are superior to those derived by assuming that farmers solve a deterministic control problem. The low levels of agricultural labor effort commonly observed in the survey area are shown to be a consequence both of the low productivity of labor in archaic rainfed agriculture and of farmers' awareness that, in the absence of a labor market, overly ambitious production plans lead to seasonal manpower constraints. To meet rainfed farmers' concerns, agricultural research institutes and extension services should factor flexibility into their research agendas.