An optimal system design process for a Mars roving vehicle

The problem of determining the optimal design for a Mars roving vehicle is considered. A system model is generated by consideration of the physical constraints on the design parameters and the requirement that the system be deliverable to the Mars surface. An expression which evaluates system performance relative to mission goals as a function of the design parameters only is developed. The use of nonlinear programming techniques to optimize the design is proposed and an example considering only two of the vehicle subsystems is formulated and solved

Updating and estimating a Social Accounting Matrix using cross entropy methods

The problem in estimating a social accounting matrix (SAM) for a recent year is to find an efficient and cost-effective way to incorporate and reconcile information from a variety of sources, including data from prior years. Based on information theory, the paper presents a flexible “cross entropy” (CE) approach to estimating a consistent SAM starting from inconsistent data estimated with error, a common experience in many countries. The method represents an efficient information processing rule—using only and all information available. It allows incorporating errors in variables, inequality constraints, and prior knowledge about any part of the SAM. An example is presented applying the CE approach to data from Mozambique, using a Monte Carlo approach to compare the CE approach to the standard RAS method and to evaluate the gains in precision from utilizing additional information.Social accounting Mathematical models. ,Mozambique. ,Economics Models. ,Entropy (Information theory) ,

Estimating Agricultural Production Functions from Experimental Data for Different Crops in Relation to Irrigation, Fertilization and Soil Management in Northern Utah

Estimates of agricultural production functions from experimental data for four different crops in relation to six variable inputs are calculated by this study. There are four basic sections in the study. The first section covers the review of production function concepts and the procedures and problems that specifically pertain to this study. Also the importance of joint economic-agronomic research efforts, methodologies and applications of agricultural production functions are cited. The second section includes the presentation data and postulated functional relationships in estimating production functions. Model building programs are used in developing three dimensional figures, which aid in the selection of the appropriate model. A multiple regression model using linear, non-linear and interaction terms is employed in deriving three production function for each crop. The problem of selecting a best model from the above three models is solved on the basis of economic theory, observed biologic physical production process, projected three dimensional production surfaces and statistical analyses. The polynomial form was selected as the best model for each crop. The third section of this study analyzes the results and the economic implications. Optimal rates of input use are determined. Qualification of these results are required because of the non significant statistical relationships including the F values of the regression coefficients and relatively low coefficient of determination (R2), and, also, because some optimal inputs values did not seem reasonable relative to observed rates. Further statistical analyses are carried out to determine the confidence interval for each input\u27s marginal productivity and this results in unbounded solutions. As an alternative, the above confidence interval problem is rephrased as a system of equalities and solved simultaneously to obtain optimal input levels at the marginal productivities maximum and minimum values and these estimates are shown not to be confidence intervals. Finally, in the fourth section of this study, summary and conclusions are given. Also, limitation and recommendations to the study are discussed

System design optimization for a Mars-roving vehicle and perturbed-optimal solutions in nonlinear programming

Work in two somewhat distinct areas is presented. First, the optimal system design problem for a Mars-roving vehicle is attacked by creating static system models and a system evaluation function and optimizing via nonlinear programming techniques. The second area concerns the problem of perturbed-optimal solutions. Given an initial perturbation in an element of the solution to a nonlinear programming problem, a linear method is determined to approximate the optimal readjustments of the other elements of the solution. Then, the sensitivity of the Mars rover designs is described by application of this method

Application of mathematical programming techniques to power system optimization

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Determining the optimum level of resource allocation on cotton farms in Southwest Tennessee by Linear Programmming technique

Cotton production is one of the most important farm enterprises in the farm economy of the United States; According to the 1954 Census of Agriculture cotton was grown on 18.1 percent of all farms and on 5.7 percent of the cropland harvested. The farm cash receipts from cotton lint and cotton seed were 7 percent of total farm cash receipts recorded in 1954. In the Old South, the farm income from cotton was 35 percent of total farm income from all enterprises. In the midsouthern hilly area, classified as Region III in the special report on cotton, and in which the present study area is located, cotton is also of major importance. In 1954, 66.9 percent of all farms in this region grew cotton; and the farms which obtained major share of income from cotton - the cotton farms, made up 89.1 percent of all commercial farms. The farms were classified in the 1954 Census of Agriculture, into six economic groups. The percentage distribution of cotton farms among these economic classes is quite revealing in that it provides strong indicators of the low average income of cotton farms in this region. For example, only 1.3 percent of Cotton farms had gross sales of $10,000 or more in 1954, but 75.6 percent had gross income of less than$2,500. Less than a fourth were in the $2,500-$9,999 income group. The corresponding figures for the whole of United States were 21.9 percent, 49.3 percent, and 28.8 percent, respectively

Building coalitions, creating change: An agenda for gender transformative research in agricultural development

The CGIAR Research Program on Aquatic Agricultural Systems (AAS) has developed its Gender Research in Development Strategy centered on a transformative approach. Translating this strategy into actual research and development practice poses a considerable challenge, as not much (documented) experience exists in the agricultural sector to draw on, and significant innovation is required. A process of transformative change requires reflecting on multiple facets and dimensions simultaneously. This working paper is a collation of think pieces, structured around broad the mes and topics, reflecting on what works (and what does not) in the application of gender transformative approaches in agriculture and other sectors, and seeking to stimulate a discussion on the way forward for CGIAR Research Programs (CRPs) and other programs to build organizational capacities and partnerships

Analytical continuum mechanics \`a la Hamilton-Piola: least action principle for second gradient continua and capillary fluids

In this paper a stationary action principle is proven to hold for capillary fluids, i.e. fluids for which the deformation energy has the form suggested, starting from molecular arguments, for instance by Cahn and Hilliard. Remark that these fluids are sometimes also called Korteweg-de Vries or Cahn-Allen. In general continua whose deformation energy depend on the second gradient of placement are called second gradient (or Piola-Toupin or Mindlin or Green-Rivlin or Germain or second gradient) continua. In the present paper, a material description for second gradient continua is formulated. A Lagrangian action is introduced in both material and spatial description and the corresponding Euler-Lagrange bulk and boundary conditions are found. These conditions are formulated in terms of an objective deformation energy volume density in two cases: when this energy is assumed to depend on either C and grad C or on C^-1 and grad C^-1 ; where C is the Cauchy-Green deformation tensor. When particularized to energies which characterize fluid materials, the capillary fluid evolution conditions (see e.g. Casal or Seppecher for an alternative deduction based on thermodynamic arguments) are recovered. A version of Bernoulli law valid for capillary fluids is found and, in the Appendix B, useful kinematic formulas for the present variational formulation are proposed. Historical comments about Gabrio Piola's contribution to continuum analytical mechanics are also presented. In this context the reader is also referred to Capecchi and Ruta.Comment: 52 page