Showing papers by "University of the Philippines published in 1972"

The Vibration of Cantilever Beams of Fiber Reinforced Material

Abstract: Experimental results were obtained for the natural frequencies and the mode shapes of graphite-epoxy and boron-epoxy composite materials having fiber orientations of 0°, 15° , 30° and 90° with respect to cantilever beam axes. Certain elastic constants were experimentally determined and used in a programmed numerical solution in which rotary inertia, trans verse shear, and coupled bending-torsion effects were included. The experi mental results for the 15° and 30° beams gave a clear indication of the interaction between bending and twisting and good agreement was obtained with the numerical results.

The Exact Finite-Sample Distribution of the Limited-Information Maximum Likelihood Estimator in the Case of Two Included Endogenous Variables

Abstract: This article is concerned with the exact finite-sample distribution of the limited-information maximum likelihood estimator when the structural equation being estimated contains two endogenous variables and is identifiable in a complete system of linear stochastic equations. The density function derived, which is represented as a doubly infinite series of a complicated form, reveals the important fact that for arbitrary values of the parameters in the model, the LIML estimator does not possess moments of order greater than or equal to one

Ethrel-induced ripening of immature and mature-green tomato fruits

Abstract: Ethrel accelerated the ripening of both immature and mature-green ‘2029’ tomato fruits. The best concentrations and time of dipping used were 2500 to 10,000 ppm and 5 minutes, respectively. Addition of surfactants and DMSO did not markedly influence the effectivity of Ethrel. Ethrel-treated fruits harvested 21 and 28 days after fruit set ripened normally but 14 day old fruits did not.

Who Benefits from the Post-Harvest Rice Price Rise?

Abstract: Economists are guilty along with sociologists of perpetuating the stereotype that because the farmer lacks finance, he is forced to sell his crop before or immediately after harvest, driving prices down. vVith credit, he could benefit by the higher post­ harvest prices. Sacay gives emphasis to this stereotype as follows: "As a result of this (production) seasonality, prices are depressed during peak production periods and high during off-season months. For a farmer to take advantage of high prices, he must postpone the sale of his products. However, since the general level of farm income is low, agricultural products have to be sold immediately after harvest unless advances on future sales such as commodity loans are obtained."]) Mabbun in his use of the stereotype brings out the additional connotation that the middleman by buying at low prices benefits at the expense of the farmer, with a windfall from high prices going somehow automatically to those who can afford to hold stocks for later sale. 2 ) There is both truth and fallacy in this stereotype but it it only recently that studies are providing empirical evidence for distinguishing between the two. The authors have demonstrated elsewhere that intraseasonal price fluctuations in the Philippines can be large in some years even though seasonal indices indicate small price spreads approaching the costs of holding. 3 ) Years with large annual price spreads were found to be interspersed with years with little or even negative price movements. In India, recent studies demonstrated a similar year to year balancing in a number of rice, wheat and sorghum markets. On average over the years, prices rose seasonally