ECONOMIC ANALYSIS OF ALTERNATIVES TO MANUAL SORTING USING SELECTED ELECTRONIC GRADERS IN ASPARAGUS FRESH PACKING

Supplying quality fresh asparagus to the consumer begins with rapid handling at the fresh packing shed, which in turn requires a significant amount of labor. This study analyzed the effects of reducing the required labor by using selected electronic graders in the grading and sorting process of fresh asparagus packing firms. Four alternative electronic graders were considered by using two throughput scenarios of 680 and 880 kg/h with 25 people. The electronic graders generated labor savings in all cases. In the first scenario, substituting technology for labor produced modified internal rates of return (MIRR) of between 30 and 39%. All four graders in the second scenario had positive returns, with an MIRR range of 8 to 21%. The electronic graders have the potential to increase the profitability of fresh asparagus packing firms.     

Strength Improvement in Transformation-Toughened Alumina by Selective Phase Transformation

A1₂O₃-15 vol% ZrO₂ bar-shaped ceramic specimens were fabricated in the green state in such a way that the near surface regions consisted of A1₂O₃ and unstabilized ZrO₂ while the bulk consisted of A1₂O₃ and partially stabilized ZrO₂. After sintering, specimens had macroscopic residual compressive surface stresses and balancing interior tensile stresses due to the tetragonal-to-monoclinic phase transformation in the outer layers which occurs during cooling. The depth of the surface region was controlled during green forming. Residual surface compressive stresses at room temperature varied between 100 and 400 MPa depending on the outer-layer thickness. The increased strengths of the three-layer specimens were obtained in the as-fired unground condition, demonstrating that the stresses introduced are the result of transformation of tetragonal zirconia into monoclinic polymorph which occurred upon cooling from the sintering temperature. Specimens with residual surface compressive stresses were 200 MPa stronger at 750°C than monolithic specimens, demonstrating the viability of this approach for improving elevated-temperature mechanical properties.     

Efficiency in public schools: a case study in non-parametric measurement

This study illustrates the problem of efficiency measurement in stochastic input-output systems when market price data are unavailable. Efficiency comparisons by non-parametric methods are attempted for selected public elementary schools in California for 1976-77 and 1977-78. A suitable linear programming model is developed for the efficiency frontier in the input-output space, which is found to be significantly different from an average relation. This is shown to have important policy implications for improving input performance for better efficiency.     

Portfolio performance of mutual funds: efficiency and robustness

Empirical analysis often mutual funds randomly selected from Jensen's study over a twenty-year period (1945-64) is used to test (l) the risk-return efficiency frontiers, and (2) the robustness in terms of minimax levels of variance. The statistical tests confirm that balanced funds and balanced portfolios are more robust than the so-called growth funds and growth portfolios. Tests on optimal ordering and selection of the best population also show that the mutual fund with the highest sample mean return has a very low probability of identifying the best population distribution, i.e. with a highest mean return     

Morphostructural analysis,radar and SPOT image interpretation as tools for petroleum exploration: an example from the Gabian-Pezenas area (Herault,Southern France)

To determine the neotectonic framework of the Gabian-Pezenas area for oil exploration purposes, we have applied a multi-scale approach utilizing the anomalies of the drainage patterns, the radar and SPOT analyses, followed by field data confirmations and seismic profile interpretations. Existing structural data have been reinterpreted. They result in the extension of the Gabian Fault towards the South, and in the recognition of an important detachment fault previously interpreted as a major thrust. Such a multisouree and multiscale approach may provide data critical for the identification of potential oil prospects.     

MELTING OF ICE AROUND A HORIZONTAL ISOTHERMAL CYLINDRICAL HEAT SOURCE

Processes during melting from a horizontal cylindrical heat source of uniform surface temperature embedded in ice have been studied experimentally. The volume of the melt and its shape were photographed at different times for various constant temperatures of the heat source. At early times and under all conditions, the melt occupied a cylindrical annulus. At later times free convective motion caused pear-shaped melt contours which pointed downward when the temperatures of the heat source were below 7°C and upward when the temperatures were above 8°C. Instabilities in cellular natural convection motion resulted in waviness of the interface. The location and magnitude of these ripples were found to depend on the temperature of the heat source and the melt layer thickness. Shadowgraph techniques were used to determine local heat transfer coefficients at the heat source surface.     

Vacuum Infiltration of Polyamines Increases Firmness of Strawberry Slices Under Various Storage Conditions

Strawberry slices were vacuum infiltrated with polyamines and changes in firmness during storage were determined. Spermine and spermidine at 10 mM or 100 mM significantly increased firmness, whereas pu-trescine was not as effective at increasing firmness of slices stored at 1°C. The firming effect of the polyamines was similar to that of calcium chloride, and may have been due to their ability to bind to cell walls and membranes. In ripe receptacles of various cultivars which differed in firmness, putrescine (12–38 nmol/g fresh weight) and spermidine (19–33 nmoI/g fresh weight) were the predominant polyamines, while only low levels of spermine (<10 nmol/g fresh weight) were present. There was no discernible relationship between endogenous polyamine levels and fresh fruit firmness for the cultivars studied.