SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Eggerman, Chris R.; McMahon, Sarah A.; Richardson, James W.; Outlaw, Joe L..

Replaced with revised version of paper 02/02/06.

IN-PATIENT FLOW ANALYSIS USING PROMODEL (TM) SIMULATION PACKAGE

Palavras-chave: Crop model; Simulation; Input-output model; Resource /Energy Economics and Policy; C53; Q10.

Ano: 2006

URL: http://purl.umn.edu/35303

Elbeyli, Sema; Krishnan, Palaniappa.

This paper emphasizes the basic modeling approach of general in-patient flow in a major hospital in the East Coast region. Simulation was used to analyze the inpatient flow. The first objective of this study was to determine the bottlenecks for in-in-patient flow. In order to understand the general in-patient flow, some emphasis was also given to the other units such as Medical-Surgical, Telemetry, Intensive Care Units (ICU), etc. Second objective was to study the impact of bed availability on the waiting time of admitted patients in ED before being transferred to assigned beds in other units of the hospital. A preliminary model was developed and validated based on the data collected for the selected time periods (busy four months). Different what-if...

Maximum likelihood estimation of generalized linear models with covariate measurement error

Palavras-chave: Simulation; In-patient flow; Health science; Health Economics and Policy.

Ano: 2000

URL: http://purl.umn.edu/15827

Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew.

Generalized linear models with covariate measurement error can be estimated by maximum likelihood using gllamm, a program that fits a large class of multilevel latent variable models (Rabe-Hesketh, Skrondal, and Pickles 2004). The program uses adaptive quadrature to evaluate the log likelihood, producing more reliable results than many other methods (Rabe-Hesketh, Skrondal, and Pickles 2002). For a single covariate measured with error (assuming a classical measurement model), we describe a “wrapper” command, cme, that calls gllamm to estimate the model. The wrapper makes life easy for the user by accepting a simple syntax and data structure and producing extended and easily interpretable output. The commands for preparing the data and running gllamm can...

Tipo: Journal Article

Palavras-chave: Covariate measurement error; Measurement model; Congeneric measurement model; Factor model; Adaptive quadrature; Nonparametric maximum likelihood; NPMLE; Latent class model; Empirical Bayes; Simulation; Wrapper; Sensitivity analysis; Gllamm; Cme; Research Methods/ Statistical Methods.

Ano: 2003

URL: http://purl.umn.edu/116185

WELFARE EFFECTS OF ECO-LABEL PROLIFERATION: TOO MUCH OF A GOOD THING?

Lohr, Luanne.

Given that existing food eco-labels are still not well defined in consumers' experience, there is potential for new labels to generate more confusion. Consumers incur fixed costs to learn about a label's meaning. Market shares for existing certifications may be eroded by perceptions that new products are good substitutes for them. The eco-label certifier must respond with information that reduces these costs or lose consumer and producer confidence in the label. Using a model of spatial competition in attribute space, the effect of search costs and educational expenditures on market share and price for competing certifiers is simulated. The results show that educational spending and/or improvements in efficiency of educational spending increase market...

VALUE OF SOCIAL CAPITAL TO MID-SIZED NORTHERN PLAINS FARMS

Palavras-chave: Eco-labeling; Market segmentation; Organic agriculture; Product differentiation; Search costs; Simulation; Spatial competition; Environmental Economics and Policy; Marketing.

Ano: 1998

URL: http://purl.umn.edu/16642

Gustafson, Cole R..

As farms increase in size, operators often face the difficult decision of remaining loyal to local merchants or obtaining volume discounts from more distant input suppliers. When farmers bypass local merchants and buy inputs in volume from a wholesaler, they often realize a price discount but forego many services including credit forebearance. In essence, when farmers buy locally, they pay higher prices, which decreases profits and increases financial risk, but generates social capital which can be drawn upon during periods of economic adversity later in the form of credit forebearance. A theoretical model of farm financial risk evaluates borrower behavior in light of cash flow constraints, volume discounts, and social capital. Monte-carlo simulation...

RISK AND SITE FACTORS AFFECTING POTENTIAL NITROGEN DELIVERY IN THE VIRGINIA COASTAL PLAIN

Palavras-chave: Social; Capital; Financial risk; Simulation; Stochastic; Farm Management; Institutional and Behavioral Economics.

Ano: 2004

URL: http://purl.umn.edu/23677

Peng, Wei; Bosch, Darrell J..

The effects of cropland slope, distance to surface water, farmers' risk attitudes, and farmers' nitrogen (N) fertilizer applications on potential N delivery to streams and costs of reducing N delivery were evaluated for a representative Virginia peanut-cotton farm. Target MOTAD and generalized stochastic dominance were used to select preferred plans for different levels of risk aversion. Costs of reducing N delivery were lower on farms where fields were located close to surface water, where N was overapplied relative to extension fertilizer recommendations, and where the operator was risk averse. Cropland slope had less effect on cost of reducing N delivery relative to other factors.

Tipo: Journal Article

Palavras-chave: Cost; Nonpoint source pollution; Risk programming; Simulation; Stochastic dominance; Targeting; Environmental Economics and Policy.

Ano: 2001

URL: http://purl.umn.edu/15287

Risk-Adjusted Comparison of Conservation Reserve Program Payments Versus Production Payments for a Corn-Soybean Farmer

OPTIMIZING COMPLEX BIOECONOMIC SIMULATIONS USING AN EFFICIENT SEARCH HEURISTIC

Ibendahl, Gregory A..

Conservation reserve program (CRP) payments amount to several billion dollars annually. Payments are allocated to both remove land from production and to help farmers pay for conservation improvements. However, research examining whether farmers increase their utility with CRPs is limited. This paper uses simulation analysis and certainty equivalents to compare farming income to payments under the CRP. Farming income is a combination of crop production and government payments as specified in the 2002 Farm Bill. This analysis focuses on farms in three different counties in Kentucky. Results indicate that CRPs are good choices for many farmers.

Tipo: Journal Article

Palavras-chave: Certainty equivalents; Conservation; CRP; Government payments; Risk; Simulation; Q15; Q18; Q16; C15.

Ano: 2004

URL: http://purl.umn.edu/43391

Kazmierczak, Richard F., Jr..

For simulation to be truly useful for investigating many problems in agricultural economics, non-simplifying optimization techniques need to be employed. General methods for simulation optimization that do not inhibit system characterization or analysis are available, and they would appear to provide much of the mathematical and optimizing rigor demanded by economists. This paper describes the theory and algorithm of a robust and efficient simulation optimization approach, the Complex Method. An example of implementing the algorithm is illustrated using a pest management problem.

Entry, Exit, and Structural Change in Pennsylvania's Dairy Sector

Palavras-chave: Simulation; Optimization; Complex Method; Hill-climbing; Research Methods/ Statistical Methods.

Ano: 1996

URL: http://purl.umn.edu/31661

Strategies for the Agro-food Sector

Stokes, Jeffrey R..

Data on the number of Pennsylvania dairy farms by size category are analyzed in a Markov chain setting to determine factors affecting entry, exit, expansion, and contraction within the sector. Milk prices, milk price volatility, land prices, policy, and cow productivity all impact structural change in Pennsylvania's dairy sector. Stochastic simulation analysis suggests that the number of dairy farms in Pennsylvania will likely fall by only 2.0 percent to 2.5 percent annually over the next 20 years, indicating that dairy farming in Pennsylvania is likely to be a significant enterprise for the state in the foreseeable future.

Tipo: Journal Article

Palavras-chave: Dairy; Maximum entropy; Farm size; Markov chain; Simulation; Farm Management; Industrial Organization.

Ano: 2006

URL: http://purl.umn.edu/10218

An Economic Risk Analysis of No-till Management for the Rice-Soybean Rotation System used in Arkansas

Rosa, Franco.

The agro-food sector is receiving a great deal of attention for topics of general interest as the food quality, security and safety, alternative uses of crops in food/feed/fuel, growing concern for GHG (Green House Gas) emission, LCA (Life Cycle Assessment), energy consumption. In the EU policies directed to implement sustainable local agro-food systems, the AFSC (agro-food supply chain) is emerging as the central issue in planning integrated farm-food activities performed in a space-time dimension. In this paper it is presented a methodology of regional planning the AFSC supported by empirical evidences about the region FVG (Friuli Venezia Giulia). The reference product is the Mais a crop largely cultivated in the region. A composite information system is...

Tipo: Presentation

Palavras-chave: Planning procedure; Regional development plan; Multifunctional approach; Agri-food supply chain; Simulation; Agribusiness; Farm Management; Food Consumption/Nutrition/Food Safety.

Ano: 2011

URL: http://purl.umn.edu/122023

Hristovska, Tatjana; Watkins, K. Bradley; Anders, Merle M..

Arkansas is the top domestic rice producer, representing nearly half of total U.S. rice production. Sediment is one of the major pollutants in rice producing areas of Arkansas. In order to mitigate this problem no-tillage management is often recommended. No-tillage is not well understood by farmers who believe that no-till is less profitable due to lower yields offsetting cost savings. This study evaluates the profitability and variability of no-till in the typical rice-soybean rotation used in Arkansas rice production. Crop yields, prices and prices for key production inputs (fuel and fertilizer) are simulated for the rotation, and net return distributions for rice, soybean and the two-year rotation are evaluated for no-till and conventional till using...

Tipo: Presentation

Palavras-chave: Simulation; Rice-soybean; No tillage-profitability; Risk analysis; Environmental Economics and Policy; Farm Management; Resource /Energy Economics and Policy.

Ano: 2012

URL: http://purl.umn.edu/119676

Hedging Price Risk in the Presence of Crop Yield and Revenue Insurance

Mahul, Olivier.

The demand for hedging against price uncertainty in the presence of crop yield and revenue insurance contracts is examined for two French wheat farms. The rationale for the use of options in addition to futures is first highlighted through the characterization of the first-best hedging strategy in the expected utility framework. It is then illustrated using numerical simulations. The presence of options is shown to allow the insured producer to adopt a more speculative position on the futures market. Futures are shown to be performing, in terms of willingness to receive. Options are weakly performing when futures markets are unbiased, while they are more performing when futures markets are biased.

Risk Classification in Animal Disease Prevention: Who Benefits from Differentiated Policy?

Palavras-chave: Crop insurance; Hedging; Producer welfare; Simulation; Risk and Uncertainty.

Ano: 2002

URL: http://purl.umn.edu/24881

Niemi, Jarkko K.; Lyytikainen, Tapani; Sahlstrom, Leena; Virtanen, Terhi; Lehtonen, Heikki.

Risk classification of livestock farms can help stakeholders design and implement risk management measures according to the possessed risk. Our goal is to examine how differently pig farms may contribute to the societal costs of an animal disease outbreak, how valuable this information is to different stakeholders, and how it can be used to target risk management measures. We show that the costs of an outbreak starting from a certain farm can be quantified for the entire sector using bio-economic models. In further studies, this quantified risk can be differentiated so that farms and slaughterhouses internalise the full cost of risk in production decisions and inhibit animal densities, animal contact structures or other characteristics which pose a threat...

Private Decisions and Public Goods: Trade-Offs in the Conservation Programs in the New Farm Bill: Discussion

Palavras-chave: Risk classification; Animal disease; Simulation; Dynamic programming; Partial-equilibrium; Losses; Agricultural and Food Policy; Agricultural Finance; Livestock Production/Industries; Risk and Uncertainty.

Ano: 2009

URL: http://purl.umn.edu/49307

Agent-Based Modelling and Sensitivity Analysis by Experimental Design and Metamodelling: An Application to Modelling Regional Structural Change

Davis, Todd D..

The 2002 Farm Bill creates several opportunities for landowners to adopt management practices that protect and improve soil and water quality. Landowners considering enrollment in conservation programs must compare the monetary and nonmonetary costs and benefits from removing land from production agriculture. The overall purpose of this invited paper session was to improve the understanding of the factors affecting a landowner’s decision to enroll in conservation programs. Papers addressed the environmental benefits of conservation programs and compared the returns to enrolling in conservation programs to the returns from production agriculture.

Tipo: Journal Article

Palavras-chave: Certainty equivalents; Conservation; Econometrics; Government payments; Risk; Simulation; Q18; Q16; C15; C31.

Ano: 2004

URL: http://purl.umn.edu/43417

Happe, Kathrin.

This paper presents the application of the sensitivity analysis techniques Design of Experiments (DOE) and metamodelling to the agent-based model AgriPoliS, which is a spatial and dynamic simulation model of regional structural change. DOE and metamodelling provide a more systematic analysis of results of complex simulation models. When summarising the results, it becomes clear that interest rates, technical change and managerial ability influence average economic land rent the most.

Optimization of the sampling scheme for maps of physical and chemical properties estimated by kriging

Palavras-chave: Simulation; Design of experiments; Metamodelling; Structural change; Research and Development/Tech Change/Emerging Technologies; C9; C15.

Ano: 2005

URL: http://purl.umn.edu/24464

Rev. Bras. Ciênc. Solo

Pereira,Gener Tadeu; Souza,Zigomar Menezes de; Teixeira,Daniel De Bortoli; Montanari,Rafael; Marques Júnior,José.

The sampling scheme is essential in the investigation of the spatial variability of soil properties in Soil Science studies. The high costs of sampling schemes optimized with additional sampling points for each physical and chemical soil property, prevent their use in precision agriculture. The purpose of this study was to obtain an optimal sampling scheme for physical and chemical property sets and investigate its effect on the quality of soil sampling. Soil was sampled on a 42-ha area, with 206 geo-referenced points arranged in a regular grid spaced 50 m from each other, in a depth range of 0.00-0.20 m. In order to obtain an optimal sampling scheme for every physical and chemical property, a sample grid, a medium-scale variogram and the extended Spatial...

Biophysical and economic models for assessing impacts of change on grazingland ecosystems

Palavras-chave: Simulation; Geostatistics; Sugar cane.

Ano: 2013

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832013000500002

Souza Neto,José de; Conner,James R.; Stuth,Jerry W..

PHYGROW, a hydrologic-based forage simulation model, was parameterized to represent a typical South Texas ranch engaged in the production of cattle and meat goats with an indigenous population of white-tailed deer. Forage production and associated stocking rates for two cattle:goat ratios were simulated with POPMIX for 20 years. Two ten-year weather scenarios, one representing normal conditions (30% drought years) and one representing dryer weather conditions (50% drought years) were analyzed. Management decision rules (ASPC) were developed for the region to produce estimates of annual animal production and operating costs for the enterprises on each of the four scenarios. These performance and cost data were then used as input into FLIPSIM, a firm level...

Soil water balance simulated by CROPGRO-Drybean model for edaphoclimatic conditions in Maringá

Palavras-chave: Simulation; Model integration; Economic impacts; Grazingland ecosystems; Management strategies.

Ano: 2001

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662001000100025

Dallacort,Rivanildo; Freitas,Paulo S. L. de; Faria,Rogério T. de; Gonçalves,Antonio C. A.; Jácome,Aleksandra G.; Rezende,Roberto.

The performance of the CROPGRO-Drybeans model for the prediction of soil water balance, as well as growth components and bean crop yield, was assessed using data from two field experiments conducted at the State University of Maringá Irrigation Technical Center, Paraná - Brazil, (latitude 23º27'S, longitude 51º57' and altitude 542 m), during the 2005 and 2006 growing season. The model simulations correlated well with measured soil moisture (r > 0.7) for both experiments. However, there were high discrepancies between measured and simulated soil moisture values on the days after rainfall. In addition, it was found that the model exaggerates the effect of water stress during the flowering phase, which leds to underprediction (19 and 29%) of crop yield.

Nitrogen efficiency in wheat yield through the biopolymer hydrogel

Palavras-chave: Water stress; Soil moisture; Simulation.

Ano: 2010

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662010000400002

Mamann,Ângela T. W De; Silva,José A. G. da; Scremin,Osmar B.; Mantai,Rubia D.; Scremin,Ari H.; Dornelles,Eldair F..

ABSTRACT Nitrogen use efficiency in wheat biomass and grain yields can be favored by the biopolymer hydrogel. The objective of the study was to analyze the use of the biopolymer hydrogel applied to the seed in the optimization of fertilizer-N on wheat biomass and grain yields, under different conditions of agricultural year and succession systems of high and reduced release of residual-N. In the study, two experiments were conducted, with different farming systems, soybean/wheat and maize/wheat, one to quantify the biomass yield rate and the other to determine grain yield. The experiments were conducted in the years 2014 and 2015, in a randomized block design with four replicates in a 4 x 4 factorial scheme, corresponding to hydrogel doses (0, 30, 60 and...

Water distribution from medium-size sprinkler in solid set sprinkler systems

Palavras-chave: Triticum aestivum; Simulation; Farming systems; Water stress.

Ano: 2017

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662017001000697

Prado,Giuliani do.

ABSTRACT The study aimed to evaluate the water distribution from a medium-size sprinkler working in solid set sprinkler systems. Water distribution radial curves from the sprinkler operating under four nozzle diameter combinations (4.0 x 4.6; 5.0 x 4.6; 6.2 x 4.6 and; 7.1 x 4.6 mm) and four working pressures (196; 245; 294 and 343 kPa) were evaluated on the sprinkler test bench of the State University of Maringá, in Cidade Gaúcha, Paraná, Brazil. The sixteen water distribution curves were normalized and subjected to clustering analysis (K-Means algorithm), identifying the occurrence of normalized distribution curves with three different geometric shapes. A computer algorithm, in Visual Basic for Applications in Excel spreadsheet, was developed to simulate...