Floating vs flying: A propulsion energy comparison

Floating craft are compared to those that fly. Drag/weight for floaters is shown to be proportional to v squared/L, while for flyers it is independent of size and speed. The transportation market will therefore assign airships to lower speeds than airplanes, and will favor large airship sizes. Drag of an airship is shown to be only 11 percent of submarine drag at equal displacement and speed, raising the possibility that airships can compete with some types of ships

THE ECONOMICS OF FLOW ENHANCEMENT VS. NUTRIENT CONTROLS IN MEETING WATER QUALITY STANDARDS

This paper explores the economics of using enhanced flow as part of a strategy to meet water quality standards. We begin by briefly sketching the relevant economic theory, which we then apply to a case study of a dissolved oxygen impaired stream segment in Georgia's Flint River Basin. Results show that meeting targeted water quality standards with strategies that include enhanced flow is significantly less costly than relying only on agricultural management practices.Environmental Economics and Policy,

Characterization of SLM Printed 316L Stainless Steel and Investigation of Microlattice Geometry

The goal of this project was firstly to characterize Cal Poly’s SLM printed 316L stainless steel. SEM analysis showed Cal Poly’s as-printed 316L material to have a cellular dendritic microstructure containing mostly austenite and a small amount of δ-ferrite. After being heat treated to eliminate warp, its yeild and ultimate tensile strength were on par with the literature, however higher modulus and lower elongation were observed. XRD analysis confirmed residual stresses in the material, and that grains are preferentially oriented in both heat treated and non heat treated samples. The amount of porosity in the material was found to be about 0.93%, and the material experiences ductile fracture. The second part of the project was to test four different microlattice geometries in uniaxial compression, the octet truss was the most efficient geometry having the highest specific stiffness

Effects of Female Sex Hormones and Dietary Magnesium Levels in Sheep

The major objectives of this study were to evaluate (a) the effects of diet on magnesium, calcium and potassium metabolism in yearling wethers and (b) the effects of progesterone, estradiol and diethylstilbestrol (DES) on the metabolism of the minerals. A two by two factorial design was selected whereby twelve yearling crossbred wether lambs were divided into four groups of three. One group was fed a basal diet plus magnesium along with hormones, one group was fed a basal diet plus magnesium without hormones, one group was fed a magnesium-deficient diet along with hormones, and one group was fed a magnesium-deficient diet without hormones. During trial one, two of the groups were injected intramuscularly with progesterone every twelve hours for four consecutive days. Then, forty-eight hours after the last injection of progesterone, 100 μg of estradiol was injected intramuscularly in two separate injections (50 μg per injection) six hours apart. This was intended to simulate the hormonal milieu of an ewe coming into estrus. At the time of the initial injection of estradiol, 61.3 μc of magnesium-28 and 701 μc of calcium-45 were administered orally via a lubricated balling gun to each of the wethers. Whereas during trial two, four mg DES was administered orally for twenty-one days while consuming either the basal diet plus magnesium or a magnesium-deficient diet. The major finding of this research was that when animals were fed a magnesium-deficient diet along with a high-potassium level in the diet there was a greater retention of potassium than in animals fed a basal diet plus magnesium and a high level of potassium. The progesterone and estradiol stimulated appetite, increased calcium and magnesium intake, increased calcium and magnesium excretion in the urine and feces, increased retention of potassium, increased plasma potassium, decreased plasma calcium, increased the calcium-45 in urine and increased the calcium-45 in the plasma at peak levels (p \u3c 0.05). The interaction of these two hormones with diet showed that the animals that were fed the basal diet plus magnesium and injected with hormones excreted more magnesium-28 for the twenty-four and forty-eight hour test period, and for the complete test period. The animals fed DES consumed less feed, consumed less calcium and magnesium, excreted less calcium and magnesium in the feces, excreted more magnesium in the urine, and excreted less calcium in the urine and had a greater concentration of magnesium in the plasma. The interaction of DES X diet showed that the animals that were fed DES and maintained on a magnesium-deficient diet had the least amount of plasma potassium of any group

Hazardous Waste Exportation: The Global Manifestation of Environmental Racism

During the last decade, the United Nations and other international organizations have been struggling with the issue of hazardous waste exportation to developing countries. At the same time, the United States has been grappling with environmental racism. However, critics of both hazardous waste exportation and environmental racism have overlooked their similarities, namely, that hazardous waste exportation and environmental racism place a disproportionate burden on the same classes of people, the poor and minorities. The exportation of hazardous waste to developing countries is essentially environmental racism on an international scale. This Note briefly explains the history and economic motivations behind hazardous waste exportation and environmental racism. Several key international agreements and current U.S. policy are analyzed to determine their effectiveness in reducing the export of hazardous waste to developing nations. In comparison, studies suggesting a link between race, income, and the location of hazardous waste facilities in the United States are outlined, along with current U.S. policy on environmental racism. The Note concludes that the similarities between the two problems should enable opponents of both to join forces to reduce hazardous waste generation and to advocate the equitable location of hazardous waste facilities

A system of open spaces for outdoor recreation in metropolitan areas

M.S.Malcolm G. Little, Jr