Search results

A linear programming method has been used to design antenna array patterns that suppress interference from certain directions. The method is particularly useful since any degree of suppression can be specified. It is not necessary to impose exact nulls onto the pattern, although this can be done if desired. Moreover, by constraining real excitations to lie in the interval [‐1, 1], a pattern is obtained in which the majority of excitations remain at the quiescent value of unity. The method can be modified in principle to incorporate any other appropriate linear equality or inequality constraints on the pattern or the excitations. A detailed description of the method is given and several illustrative examples are included.

This study estimates the probability density function of the government’s net income from reinsuring crop insurance for corn, wheat, and soybeans. Based on 1997 data, it is estimated there is a 5% probability that the government will need to reimburse at least $1 billion to insurance companies, and that the fair value of the government’s reinsurance services to insurance firms equals $78.7 million. In addition, various hedging strategies are examined for their potential to reduce the government’s reinsurance risk. The risk reduction achievable by hedging is appreciable, but use of derivative contracts alone is clearly no panacea.

This register of current research in social economics has been compiled by the International Institute of Social Economics. The register does not claim to be comprehensive but is merely an aid for research workers and institutions interested in social economics. The register will be updated and made more comprehensive in the future but this is largely dependent on the inflow of information from researchers in social economics. In order to facilitate this process a standardised form is to be found on the last page of this register. Completed forms, with attached sheets as necessary, should be returned to the compiler: Dr Barrie O. Pettman, Director, International Institute of Social Economics, Enholmes Hall, Patrington, Hull, N. Humberside, England, HU12 OPR. Any other comments on the register will also be welcome.

Heat also facilitates the transmission of water through the cell walls, thereby assisting its passage from the interior to the surface of the material; it increases the vapour pressure of water, thus increasing its tendency to evaporate; and it increases the water‐vapour‐carrying capacity of the air. In the United States the unit of heat customarily used is the British thermal unit (B.t.u.), which for practical purposes is defined as the heat required to raise the temperature of a pound of water 1° F. Heat is commonly produced through the combustion of oil, coal, wood, or gas. Heating by electricity is seldom practicable because of its greater cost; but where cheap rates prevail it is one of the safest and most efficient, convenient and easily regulated methods. Direct heat, direct radiation and indirect radiation are the types of heat generally employed. Direct‐heating systems have the highest fuel or thermal efficiency. The mixture of fuel gases and air in the combustion chamber passes directly into the air used for drying. This method requires the use of special burners and a fuel, such as distillate or gas, which burns rapidly and completely, without producing soot or noxious fumes. The heater consists simply of a bare, open firebox, equipped with one or more burners, an emergency flue to discharge the smoke incidental to lighting, and a main flue, through which the gases of combustion are discharged into the air duct leading to the drying chamber. Direct‐radiation systems also are relatively simple and inexpensive and have a fairly high thermal efficiency. A typical installation consists of a brick combustion chamber with multiple flues, which carry the hot gases of combustion back and forth across the air‐heating chamber and out to a stack. The air is circulated over these flues and heated by radiation from them. The flues are made of light cast iron or sheet iron. The air‐heating chamber should be constructed of fireproof materials. The efficiency of the installation depends upon proper provision for radiation. This is attained by using flues of such length and diameter that the stack temperatures will be as low as is consistent with adequate draught. Heating the air by boiler and steam coils or radiators is an indirect‐radiation system, as the heat is transferred from the fuel to the air through the intermediate agency of steam. Such a system costs more to install and has a lower thermal efficiency than either of the other two systems. It is principally adapted to large plants operating over a comparatively long season on a variety of materials where the steam is needed to run auxiliary machinery or to process vegetables. Large volumes of air are required to carry to the products the heat needed for evaporation and to carry away the evaporated moisture. Insufficient air circulation is one of the main causes of failure in many dehydrators, and a lack of uniformity in the air flow results in uneven and inefficient drying. The fan may be installed to draw the air from the heaters and blow it through the drying chamber, or it may be placed in the return air duct to exhaust the air from the chamber. An advantage of the first installation is that the air from the heaters is thoroughly mixed before it enters the drying chamber. It has been claimed that exhausting the air from the chamber increases the rate of drying by reducing the pressure, but the difference is imperceptible in practice. Either location for the fan is satisfactory, and the chief consideration in any installation should be convenience. Close contact between the air and the heaters and between the air and the material is necessary for efficient transfer of heat to the air and from the air to the material, and to carry away the moisture. The increased pressure or resistance against which the fan must operate because of such contact is unavoidable and must be provided for, but at other points in the system every effort should be made to reduce friction. To this end air passages should be large, free from constrictions, and as short and straight as possible. Turns in direction should be on curves of such diameter as will allow the air to be diverted with the least friction. The general rule in handling air is that a curved duct should have an inside radius equal to three times its diameter. The water vapour present in air at ordinary pressures is most conveniently expressed in terms of percentage of relative humidity. Relative humidity is the ratio of the weight of water vapour actually present in a space to the weight the same space at the same temperature would hold if it were saturated. Since the weight of water vapour present at saturation for all temperatures here used is known, the actual weight present under different degrees of partial saturation is readily calculated from the relative humidity. Relative humidity is determined by means of two thermometers, one having its bulb dry and the other having its bulb closely covered by a silk or muslin gauze kept moist by distilled water. Tap water should not be used because the mineral deposits from it clog the wick, retard evaporation, and produce inaccurate readings. The wick must be kept clean and free from dirt and impurities. The two thermometers are either whirled rapidly in a sling or used as a hygrometer mounted on a panel with the wick dipping in a tube of water and the bulbs exposed to a rapid and direct current of air. The relative humidities corresponding to different wet‐ and dry‐bulb temperatures are ascertained from charts furnished by the instrument makers, or published in engineers' handbooks. As a general rule, the more rapidly the products have been dried the better their quality, provided that the drying temperatures used have not injured them. Some fruits and vegetables are more susceptible to heat injury than others, but all are injured by even short exposures to high temperatures. The duration of the exposure at any temperature is important, since injury can be caused by prolonged exposure at comparatively moderate temperatures. The rate of evaporation from a free water surface increases with the temperature and decreases with the increase of relative humidity of the air.

Under the Thatcher Government′s “Enterprise Culture”, the size of the small business sector has frequently been taken as a key indicator of economic success in Britain. Measurement of achievement in such terms does indeed indicate a high degree of economic buoyancy. However, a deeper examination of available data indicates that much of this success may be illusory and dependent for its survival on substantial levels of state intervention. At the same time, an examination of regional patterns of small business success reveals a picture somewhat similar to that pertaining to the economy as a whole. Far from raining down success selectively on economically deprived areas, as had been hoped in some circles, it appears that it is the most prosperous areas which tend to support the highest levels of enterprise.

The purpose of this paper is to propose a method for solving nonlinear fractional partial differential equations on the semi-infinite domain and to get better and more accurate results.

The authors proposed a method by using the Chebyshev wavelets in conjunction with differential quadrature technique. The operational matrices for the method are derived, constructed and used for the solution of nonlinear fractional partial differential equations.

The operational matrices contain many zero entries, which lead to the high efficiency of the method and reasonable accuracy is achieved even with less number of grid points. The results are in good agreement with exact solutions and more accurate as compared to Haar wavelet method.

Many engineers can use the presented method for solving their nonlinear fractional models.

Both accounting and regulatory treatments classify securitizations as a “sale” of assets, therefore allowing the issuer to remove the assets from their books. The purpose of this paper is to present conjectural evidence of recourse activity and bankruptcy treatment that undermine the fundamental concept of true sale.

The authors use investor reactions to firm’s first securitizations to isolate investors’ views of the potential risk transfer.

Investor reactions to firms’ first securitization announcements suggest that investors, themselves, think of the effects of securitizations as more like a financing than an asset sale. Firms securitizing for the first time exhibit negative short-term equity returns and negative long-term operating performance, reactions more similar to financings than asset sales. Additional analysis shows that securitization is also associated with increased systematic risk, suggesting that the rapid growth fueled by securitization is similar to increasing leverage. The effect is more pronounced for banks than non-banks.

This is the first study to have used firms' first securitizations to analyze the nature of risk transfer in securitizations. The results show that off-balance-sheet treatment for securitizations may be inappropriate, given investor perceptions of the nature of potential contingent liabilities.

An economic analysis is presented of the Standard Reinsurance Agreement (SRA), the contract governing the relationship between the Federal Crop Insurance Corporation and the private insurance companies that deliver crop insurance products to farmers. The paper outlines provisions of the SRA and describes the modeling methodology behind the SRA simulator, a computer program developed to assist crop insurers and policy makers in assessing the economic impact of the Agreement. The simulator is then used to analyze how the SRA affects returns from underwriting crop insurance. The results are presented in aggregate and also at the regional and individual company levels.

There have been many innovations in public finance in the 21st century to address increasing budget constraints and increasing demands from government. One innovation has been civic crowd-funding which began in 2009. This is predicated on the voluntary commitment of funds by individual and institutional donors and investors for specific projects. This paper explores this new approach to funding capital projects and grounds it within a discussion of the Voluntary Theory of Public Finance. There is a lack of research on civic crowd-funding and a lack of theoretical approaches to it. This paper draws these connections and develops future directions of research that includes the continuing application of this approach, the increasing engagement of citizens in the administrative process of government and increasing budget constraints.

While a relationship between accountability and ethics has long been assumed and debated in Public Administration, the nature of that relationship has not been examined or clearly articulated. This article makes such an effort by positing four major forms of accountability (answerability, blameworthiness, liability and attributability) and focusing on the ethical strategies developed in response to each of these forms