• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 96
  • 63
  • 44
  • 34
  • 30
  • 20
  • 20
  • 20
  • 20
  • 20
  • 16
  • 16
  • 11
  • 6
  • 5
  • Tagged with
  • 394
  • 69
  • 68
  • 67
  • 53
  • 46
  • 43
  • 39
  • 38
  • 37
  • 29
  • 23
  • 22
  • 21
  • 20
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

The design of a residential water-to-water heat pump

Linder, Charles Augustus January 1956 (has links)
The residential heat pump is becoming more and more important as a means of heating and cooling homes. The American family is booming increasingly aware of year—round air conditioning in all its various aspects, not only for hosting and cooling the homo, but also for humidity control and air filtration. All those tasks may be accomplished with the installation of a single heat pump unit. Aside from the relatively new concept of cooling buildings during the summer, the heat pump has very distinct advantages when its use as a means of heating alone is considered. The heat pump uses electricity to heat. The individual can perceive immediate advantages in this aspect. The dirt and noxious gases of petroleum or coal combustion are eliminated. The fuel handling and combustion by-product removal equipment are no longer necessary. There is a significant reduction of fire hazard which should be reflected in lower fire insurance costs. The installation of a heat pump would be a distinct advantage architecturally because the heating unit no longer must be placed in a basement or large utility room adjacent to a chimney and fuel storage. In communities where smoke or smog conditions have become serious, extensive installation of electric heating apparatus would be most beneficial. Unless the consumer is willing to assign a monetary value to the afore-listed advantages of the heat pump, he will generally find that in areas where electricity costs over 1-1/2 cents per KWH, it is more expensive to operate than a conventional heating plant.(1O) This figure will of course vary with local fuel costs, heat loads, and heat pump coefficient of performance (COP). In recent years power companies have enthusiastically encouraged the widespread installation of electric heating apparatus, such as the heat pump, by attempting to make their operating costs competitive to other forms of heating. The reason for this encouragement may easily be detected by studying power consumption statistics. The influx of an increasing number of electrical appliances into the home has greatly increased the average power consumption in most areas. However this power consumption varies greatly with the time of day, being at a peak in the early evening, and at a relatively very low minimum in the early morning hours. The utility companies must install sufficient capacity to carry these peak loads, and therefore have machinery idle or operating below rated load and efficiency during the minimum consumption periods. To help offset this economically adverse condition, the power companies are in many areas willing to give rate discounts to consumers using electric heating, as the greatest capacity demands are placed on these units during the minimum power consumption hours. Owners of heat pumps may receive power rate discounts generally in one of two ways, either by a reduced cost per KWH over a certain number, or by the installation of a power meter in which time is integrated with the rate of flow of power, giving a separate or a numerically reduced reading during the off peak hours. The former method is in more widespread use today, however the latter method, although more involved and costly, seems to be more in line with power company objectives. The author has been commissioned as consultant to the architect to design a heat pump system for a proposed residence for Brig. General C. H. Shuey, U.S.H.C. (Ret.). This home is to be built on Sinnepuxant Bay, Maryland. The architect has specified heating is to be accomplished by means of a radiant floor panel. This requirement together with the proximity of a boundless supply of water to use as the heat pump sink and heat source, suggests the use of a water-to—water heat pump system. As a radiant floor panel cannot be used to cool, auxiliary air refrigerating apparatus will have to be installed. The objects of this thesis will be to compute the heating and cooling requirements for the building; to design the radiant floor panels and auxiliary cooling apparatus; and to design the water-to-water heat pump and its associated equipment. / Master of Science
52

A study and evaluation of methods of estimating runoff from agricultural watersheds

Parsons, Bernard Lee January 1956 (has links)
Master of Science
53

The design of a pilot plant for the production of monosodium glutamate

Luttrell, Robert S. January 1956 (has links)
The production of monosodium glutamate has grown from a by-product of the sugar beet industry to an important position in today’s food commodities. Monosodium glutamate is made from Steffan's waste, corn gluten, wheat gluten, and other similar proteinaceous materials. In trying to find moro and better uses for soybeans, it was discovered that soybean meal was an excellent raw material for making monosodium glutamate because of the high percentage of proteins in the meal . For years in the Far East, soybean meal has been utilized for the production of monosodium glutamate, but American industry had to be educated to make use of the potential of the soybean. For the various processes required for the isolation and purification of glutamic acid for the conversion into monosodium glutamate, the yields obtained have been low of the order of between 50 and 70 percent by weight of the total glutamic acid originally contained in the proteinaceous substances processed. The difficulty involved in the manufacture of monosodium glutamate is in getting the glutamic acid in a refined state. Other amino acids are obtained during the initial hydrolysis step, and they are difficult to remove to obtain the "edible" glutamic acid of commerce. The proposed production of monosodium glutamate from soybean meal is an answer to higher yields and less expensive equipment and reagents. In using the soybean meal, which is itself a highly valuable cattle food, the glutamic acid is taken out leaving valuable amino acids in the waste after the initial hydrolysis step. Therefore, this waste referred to as humin can be sold as a hydrolyzed cattle food. It was the purpose of this investigation to design a pilot plant for the production of monosodium glutamate. The problem involved the investigation of synthesis methods and conditions, cost analyses, and actual design of the pilot plant. / Master of Science
54

Polarography applied to nitrate determination in sanitary water analysis

Thompson, Richard Lewis January 1956 (has links)
The purpose of the investigation was to determine the interfering effect on the polarographic method of nitrate analysis of certain chemicals commonly employed in the water purification process. Chemicals tested consisted of coagulants, a disinfectant, and an algaecide. A. “synthetic” water of known chemical consistency was used for diluting purposes. The investigation consisted of two phases; (1) establishing a standard curve with 95 per cent confidence limits of nitrate concentration versus current reading, and ( 2) determining the amount of nitrate recovery in samples containing known nitrate concentrations and certain chemical additives. A further investigation was made of the effect of chemicals revealing a pronounced interference during the initial test. The results obtained indicated that ferric chloride, ferric sulfate, chlorine, and copper sulfate did not interfere with the nitrate analysis. Alum and ferrous sulfate caused a significant interference. The loss in nitrate recovery due to the presence of alum in solution was found to be directly proportional to the alum concentration. Nitrate recovery was reduced from 0 to 10% by alum dosages of 0 to 10 gpg respectively. Although ferrous sulfate caused considerable reduction in nitrate recovery, this is readily explained since ferrous sulfate may be used for the destruction of nitrate in polarographic procedure. When a number of samples were analyzed, the average time required was about 20 minutes per sample. Thus, the time required to perform a nitrate analysis by the polarographic method compares favorably with other methods of analysis. / Master of Science
55

The solubility of cellulose acetate fractions

Lee, Hsueh-Ting January 1956 (has links)
no abstract provided by author / Master of Science
56

The design and construction of a magnetic analyzer for a two million volt electrostatic accelerator

Oliver, David Webster January 1956 (has links)
A magnetic analyzer capable of bending the four million electron volt bean of the Virginia Polytechnic Institute electrostatic accelerator has been constructed. The magnet is the circumferential yoke, double-focusing type. Tests show its field to be uniform within one percent along its 16-inch radius, its magnetization curve to agree with the design requirements, and its cooling system to be more than adequate. A motor-generator set and a motor amplydine have been obtained for the magnet power supply, delivery now awaited. A voltage feedback system has been designed for field stabilization, and the considerations in supplying nuclear magnetic resonance equipment to field stabilization have been examined. / Master of Science
57

A study of the attitudes of certain employers of industrial workers, toward the public schools

Haislip, Mary Sue January 1956 (has links)
M.S.
58

Intensity distribution in cylindrical and bowl shaped transducers and sono-dialysis of a caustic solution

Bakhshi, Narendra Nath 19 May 2010 (has links)
In ultrasonic processing, it has been a practice to measure intensity of ultrasonics as a product of plate current and voltage as indicated on ultra sonic generator. At low frequencies the standard equipment is available, such as the sound level meter, to measure the absolute intensity, but at higher frequencies the problem becomes complicated by the diffraction effects on account of the size of the measuring device. In this investigation an attempt has been made to construct a measuring device (called the probe) to measure intensity. A small barium titanate cylindrical element (1/16 inch in diameter and 1/16 inch length) was used as a detector-convertor of sonic pressures. The alternating voltages thus produced were indicated by a vacuum tube voltmeter. This element was cemented in a hypodermic needle in turn was held in a lucite rod (1/2 inch in diameter and five inches in length) which served as a holder. This arrangement was used to probe the sonic fields of cylindrical and bowl shaped transducers. / Ph. D.
59

Control of green June beetle larvae attacking pastures, and residues resulting from insecticidal treatments

Tombes, Averett S. 07 November 2008 (has links)
Early interest concerning the control of the green June beetle, Cotinis nitida Linn., also called the fig-eater, was recorded during the middle of the nineteenth century. Since that time farmers in Virginia and other Southeastern States have been trying to find better methods for the control of this insect. The larvae of this beetle, . en present in large numbers, are capable of almost completely destroying certain forage crops such as alfalfa and clover, not by direct feeding, but from the results of their search for food. The adult, although not of prime economic importance in this region, does cause considerable economic losses. It feeds on fruits from a number of different species of plants such as grapes, peaches, raspberries, apples, pears, plums and in particular figs, hence the common name fig-eater. A definite affinity also is shown towards certain grains such as corn and sorghum. / Master of Science
60

Lethal alleles in wild population of Mus musculus (house mice)

Beasley, Andrew Bowie 17 March 2010 (has links)
The primary objectives of this investigation were to sample a wild population of Mus Musculus in Virginia and to report on the nature of the genetic material located at a specific point on the ninth chromosomal linkage group in this species. / Master of Science

Page generated in 0.014 seconds