Towards a control model for the highly cybernetic farming ecosystems

Abstract

A dynamic model based on the linear systems theory is developed in designing a highly cybernetic farming strategy to efficiently manage residuals generated in farm ecosystems. A linear cybernetic model would be used to describe the dynamic behavior of resource flow in the farm ecosystem in which the state variables are resource quantities, and the control variables are residual quantities. The controlled process is defined as the controlled management strategy change. Cybernetic mechanism shows the application of residuals as control measures have determinate effects on the controlled process as along as the farming system is observable and controllable in the control sense. To illustrate the model algorithm the idea is applied to simulate the dynamic response of residual phosphorus concentrations in an integrated pig/corn farming system located in the south Taiwan region. General results show that the residual phosphorous concentration is influenced by farming activities which are controlled by a system of gross input and net output parameters. This paper demonstrates using input‐output analysis technique that residuals generated in the farming system is the most important cybernetic variable, so that the proper management of residuals alone has the potential to maintain future productivity and sustainability.     

MSBR法污水处理在线模糊控制的研究

MSBR法就其运行功能和效果而言,被认为是一种理想的污水处理工艺流程.由于运行过程变量多,它属于复杂的动态系统.目前采用的PID控制模式无法找到精确的模型来描述,故将模糊控制用于MSBR工艺系统控制中,对于处理效果有关的变量进行模糊控制,用模糊控制算法对处理效果的测试进行研究,并将该模糊控制算法在MATLAB上进行了仿真,结果表明系统具有较强的鲁棒性和自适应性及优良的控制性能.     

MSBR法污水处理在线模糊控制的研究

MSBR法就其运行功能和效果而言，被认为是一种理想的污水处理工艺流程。由于运行过程变量多，它属于复杂的动态系统。目前采用的PID控制模式无法找到精确的模型来描述，故将模糊控制用于MSBR工艺系统控制中，对于处理效果有关的变量进行模糊控制，用模糊控制算法对处理效果的测试进行研究，并将该模糊控制算法在MATLAB上进行了仿真，结果表明系统具有较强的鲁棒性和自适应性及优良的控制性能。     

Vulnerability of coastal livelihoods to shrimp farming: Insights from Mozambique

Millions of people around the world depend on shrimp aquaculture for their livelihoods. Yet, the phenomenal growth of shrimp farming has often given rise to considerable environmental and social damage. This article examines the impacts of commercial, export-oriented shrimp aquaculture on local livelihood vulnerability by comparing the exposure, sensitivity, and adaptive capacity of shrimp farm employees with non-farm employees in rural Mozambique. Exposure to stressors was similar between the two groups. Shrimp farm employees had higher assets and higher adaptive capacity than non-farm employees. However, because their income is heavily dependent on a single commodity, shrimp farm employees were highly susceptible to the boom crop nature of intensive shrimp farming. The implications for aquaculture policy and vulnerability research are discussed. The article argues that coastal vulnerability is dynamic, variable, and influenced by multiple processes operating at multiple scales.     

Environmental and economic impacts of decision-making at an arable farm: an integrative modeling approach

This study examines the dependency between physical and anthropogenic systems in arable farming. The dynamic simulation model, which has its methodological origins in the modeling traditions of environmental systems analysis and microsimulation, reproduces the mutual links between the physical flows (e.g. energy, materials, emissions, and products), the farmer as a decision-making agent, and structural conditions influencing the farm. In running the model, the intention is to answer the question: What are the impacts on profitability and the environment (i.e. greenhouse gas effects, eutrophication, acidification, and energy use) of variations in prices, subsidies, the farmer's environmental values, and the farmer's skill in making production allocation choices? The results of the model simulations indicate, for example, that in terms of economic performance, a farmer can choose between two relatively sustainable strategies--either to specialize in organic production (thereby benefiting from higher subsidies and output prices), or to focus on conventional cultivation and use of pesticides and fertilizers (thereby benefiting from large yields). Regarding environmental impacts, there was no clear-cut divide between organic and conventional farming due to difficulties in allocating the use of manure. This finding is essentially related to the choice of system boundary, which is thoroughly discussed in the paper.     

Resilience building of rural livelihoods in PES programmes: A case study in China’s Loess Hills

In spite of positive expectations for environmental protection, payments for ecosystem services (PES) can bring about unintended disturbances to rural livelihoods. Based on resilience thinking, this article investigates livelihood resilience building at farm level through the interaction between farm adaptation and disturbances induced by China’s Grain for Green project (GGP). Cluster analysis was conducted to investigate the complexity and diversity of farm adaptation; the crafting of composite indexes was designed to value resilience through disturbance, sensitivity, and adaptability; regression analyses linked the resilience indexes and farm adaptation with access to resources. The results show three adaptation typologies (i.e. reclamation of retired lands, contractive farming, and expansive farming) with distinct land use structures and resilience scores, and highlight the need to improving farmers’ access and endowment of tangible (e.g. farming facilities) and intangible resources (e.g. skill training) for resilience-building practices in light of the GGP. The findings imply that policy interventions combining environmental restrictions with widening resource access to support alternative livelihoods can offset the unintended effects and amplify the success of PES programmes.     

Incinerator Conference Covers Emissions Control Aspects

The success of the application of computer modeling to decision-making will depend on the degree to which the scientifically valid “cause-and-effect” features of the air pollution system are represented. For this reason, dynamic simulation models are to be preferred to statistical and empirical models. A digital simulation model based on a stoichiometrically logical chemical mechanism and trajectory estimating routines was constructed, using Los Angeles source, meteorological and geographic input. The basic physical concept underlying the simulation model is the process of evolution of photochemical pollution in a parcel of air as it moves in a dynamic urban emission/meteorological environment along a given urban wind trajectory. Both the photochemical evolution and the trajectory are numerically integrated by a standard linear multistep predictor-corrector method. Concentrations of photochemical reactants and products (i.e., primary and secondary contaminants) are determined by this numerical integration, which also includes appropriate terms for relevant effects. In five preliminary validation runs, simulated NO₂, NO, and O₃ values were within 20% or 0.05 ppm of those observed at air monitoring stations located near the termini of the runs. The trajectories were plotted on the basis of hourly meteorological data for 22 stations. Six control strategy exercises were conducted to illustrate the application of the model to problem-solving situations.     

A dynamic artificial clam (Corbicula fluminea) allows parsimony on-line measurement of waterborne metals

We introduce a novel on-line biomonitoring system based on a valvometric conversion technique for clam Corbicula fluminea, allowing for rapid, continuous, and ecological relevant water quality control. Our model builds upon the basic principles of biological early warning system model in two ways. We first adopted a risk-based methodology to build a dynamic artificial clam for simulating how the bivalve closure rhythm in response to waterborne copper (Cu) and cadmium (Cd). Secondly, we integrated a probabilistic model associated with the time-varying dose-response relationships of valve closing behavior into the mechanisms of a dynamic artificial clam, allowing estimation of the time-varying waterborne Cu/Cd concentrations for on-line providing the outcomes of the toxicity detection technique. Measurements with Cu/Cd were performed and the calculated EC50 values were compared with published data for the valve movement test with C. fluminea. This proposed dynamic artificial clam provides a better quantitative understanding of on-line biomonitoring measurements of waterborne metals and may foster applications in clam farm management strategy and ecotoxicological risk assessment.     

An application of parametric and nonparametric models to the assessment of fluoride levels in vegetation exposed to stack emissions of an aluminum reduction plant in Greece

Various statistical models were developed for assessing airborne fluoride (F) levels in natural vegetation near an aluminum reduction plant using as predictor variables the distance from the emission source, the predominating wind, and characteristic topography-geomorphology parameters. Results revealed that F concentrations in vegetation showed a predictable response to both wind conditions and landscape features. The linear model was found to give good estimations, taking advantage of the relatively strong linear correlation between concentration and distance. A nonlinear relationship between the F concentration in vegetation and the other variables was also found, while interactions between the variables were found to be non-first-order. The nonlinear relationship hypothesis was supported by the improved results of various nonlinear models that also indicated the importance of the area's topography-geomorphology and meteorology in model predictions. The application of an artificial neural network (ANN) model showed the closest agreement between predicted and observed values with a correlation coefficient of 0.92. The improved reliability of the ANN and a regression tree model (RTM) also were indicated by the normal distribution of their residuals. The RTM and the ANN were further investigated and found to be capable of identifying the importance of the variables in vegetation exposure to air emissions.     

Assessment of the potential of ecolabels to promote agrobiodiversity

We conducted a study to assess to what extent current ecolabels contain standards that stimulate conservation and sustainable use of on-farm biodiversity of agricultural landscapes (agrobiodiversity). First, we developed an agrobiodiversity management yardstick to assess and compare the labeling schemes of ecolabels for arable farming. Key characteristics of the yardstick are the five levels linking the abstract notion of agrobiodiversity management to concrete measures on a farm and its foundation upon expert judgment regarding the effect of farming practices on agrobiodiversity. Several environmental themes, among them agrobiodiversity management, are regulated through the standards of labeling schemes of ecolabels. With the aid of this yardstick, the labeling schemes were scrutinized and the number, average efficacy, and compulsory nature of relevant standards was determined for 10 categories of farm management. The results show that all examined ecolabels contain at least some standards that stimulate conservation and sustainable use of agrobiodiversity, but there are large differences between the labels. We consider the results of the five ecolabels to be insufficient to warrant their usefulness as a governance strategy that the Dutch government could refer to and depend on as part of a national agrobiodiversity policy to stimulate agrobiodiversity.     

An Evaluation of Emissions and Control Technologies for the Metal Decorating Process

A simple but effective sampling and analytical procedure is described for determining total organics, carbon dioxide, carbon monoxide, and methane emitted from web offset printing presses. Data are reported on a number of controlled and uncontrolled sources and emission levels are related to process variables such as press speed, ink coverage and dryer type. For controlled sources employing either catalytic or thermal incineration units, conversion efficiencies are reported as a function of temperature. Operational curves are presented for each control system studied indicating the dependency of carbon dioxide, NO_xt and organic output to incineration temperatures.     

Evaluation of a photochemical grid model using estimates of concentration probability density functions

A method for evaluating photochemical grid models based on the estimation of the probability density function (PDF) of the variations in ozone concentrations is described and demonstrated. It is assumed that the ozone concentration PDF is determined from 100 Monte Carlo uncertainty runs based on uncertainties in photochemical grid model input variables. The exercise involves the Urban Airshed Model with Variable grid (UAM-V) as applied to the July 1995 Ozone Transport Assessment Group episode in the eastern US. The focus is on the distribution of model residuals (observed concentration minus model-predicted ensemble mean concentration) for 66 ozone monitors on the OTAG domain. It is concluded that the distribution of observed model residuals is within the 95% range of expected uncertainty, suggesting that the model is performing adequately.     

An Evaluation of Emissions and Control Technologies for the Metal Decorating Process

Data are reported on a number of controlled and uncontrolled sources from various metal decorating operations. Emission levels are related to process variables such as ink coverage, coater speed, sheet size, and applied coating film weight. Results are presented depicting variation of organic emission levels from a coating process line with elapsed process time. For controlled sources employing either catalytic or thermal incineration, conversion efficiencies are reported as a function of temperature. Operational curves are presented for each control system studied indicating the dependence of carbon dioxide, NO_x, and organic output on incineration temperatures.     

Air emissions of ammonia and methane from livestock operations: valuation and policy options

The animal husbandry industry is a major emitter of ammonia (NH3), which is a precursor of fine particulate matter (PM2.5)--arguably, the number-one environment-related public health threat facing the nation. The industry is also a major emitter of methane (CH4), which is an important greenhouse gas (GHG). We present an integrated process model of the engineering economics of technologies to reduce NH3 and CH4 emissions at dairy operations in California. Three policy options are explored: PM offset credits for NH3 control, GHG offset credits for CH4 control, and expanded net metering policies to provide revenue for the sale of electricity generated from captured methane (CH4) gas. Individually these policies vary substantially in the economic incentives they provide for farm operators to reduce emissions. We report on initial steps to fully develop the integrated process model that will provide guidance for policy-makers.     

Farm, land, and soil nitrogen budgets for agriculture in Europe calculated with CAPRI

We calculated farm, land, and soil N-budgets for countries in Europe and the EU27 as a whole using the agro-economic model CAPRI. For EU27, N-surplus is 55 kg N ha⁻¹ yr⁻¹ in a soil budget and 65 kg N₂O–N ha⁻¹ yr⁻¹ and 67 kg N ha⁻¹ yr⁻¹ in land and farm budgets, respectively. NUE is 31% for the farm budget, 60% for the land budget and 63% for the soil budget. NS values are mainly related to the excretion (farm budget) and application (soil and land budget) of manure per hectare of total agricultural land. On the other hand, NUE is best explained by the specialization of the agricultural system toward animal production (farm NUE) or the share of imported feedstuff (soil NUE). Total N input, intensive farming, and the specialization to animal production are found to be the main drivers for a high NS and low NUE.     

Intraparticle diffusion of a basic dye during adsorption onto sphagnum peat

The adsorption of a basic dye from aqueous solutions onto peat has been examined. Intraparticle diffusion in the peat pore structure is proposed as a mass transfer mechanism. The results indicate a diffusion process in occurring by a macropore and micropore controlled process. A diffusion rate parameter, k, is proposed and is correlated with possible system variables.     

Disinfection and dewatering of wastewater solids by interstitial vapor generation.

Disinfection of wastewater solids (waste activated solids [WAS]) by interstitial vapor generation was investigated. In addition to the magnitude of disinfection, the amount of water removed and cost relative to traditional residuals disinfection processes was also examined. The process of interstitial vapor generation occurs as a result of the rapid heating of liquid in the interstices of the solid-liquid array. Intense heating causes boiling of the slurry liquid, resulting in an expanding vapor front that simultaneously dewaters the wastewater solids and contributes to the destruction of viable pathogenic microorganisms. Objectives of the study were threefold: (1) to validate disinfection of WAS using the interstitial vapor technique; (2) establish the degree of possible drying of the residuals using the techniques; and (3) establish the key operating variables for the process. Results showed a significant reduction in the most probable number of total coliforms and Escherichia coli (E. coli). Specifically, greater than four-log unit reductions were produced for both total coliform and E. coli bacteria. In addition to quantifying the reduction in bacteria, the percent solids were increased from an initial amount of 7.6% (mass basis) to a final solids content greater than 90% using optimal processing conditions. Cost comparisons were also conducted and shown to be quite favorable when compared with traditional disinfection methods such as lime addition. Because of the high level of E. coli reduction achieved, the process of interstitial vapor generation is shown to be capable of converting a class B biosolids into a class A pathogen reduced product. For example, an initial most probable number (MPN) of 1.2 x 10(6) E. coli bacteria were reduced to 19 at the extreme conditions of the process, well below the requirement of an MPN of 1000 for fecal coliform bacteria. Given its ability to disinfect and dewater wastewater solids, the interstitial vapor generation process was found to be a robust and beneficial technique to produce an environmental and publicly acceptable recyclable biosolids resource.     

The use of a multimedia risk analysis approach in designing waste management strategies

A pollution source may release residuals to any of several environmental media, depending on the process design and control strategies. These residuals then are subject to transfer, transport, and transformation within the interconnected compartments of the environmental system. The exposure and susceptibility of people and other receptors to pollutants are different in these various media, and so that risks imposed will vary according to the fate of the pollutants in the system. Because of interactions between compartments in the system, a single-medium approach to environmental management that mitigates problems in one environmental medium at a time independently of risk through other media may not minimize the aggregate risk a receptor receives from all pathways. Alternatively, a multimedia approach advocates focusing on the full environmental system providing pathways for exposure and selecting risk management strategies based on minimization of the aggregate and cumulative risk from all pathways and all compounds. This study combines multimedia risk analysis and an optimization framework to examine a methodology for selecting waste treatment/disposal and pollution control measures, applies the methodology to a sludge management decision problem, and considers the implications for continued use of single-medium analyses.     

Real-time ozone mapping using a regression-interpolation hybrid approach, applied to Tucson, Arizona

Real-time ozone (O3) maps, intended for public access and mass media, are generated from spatially interpolating (i.e., kriging) sparse monitoring data and are typically characterized by over-smoothed surfaces that inadequately represent local-scale spatial patterns (e.g., averaged over 1 km2). In this paper, a hybrid regression-interpolation methodology is developed to enhance the representation of local-scale spatiotemporal patterns with an application to Tucson, Arizona. The mapping of local patterns is enhanced with pre-interpolation regression modeling of local-scale deviation-from-mean variability, preserving variation in the monitor data that is ubiquitous across the modeling domain (i.e., the areal mean). The model is trained on several years of deviation-from-mean hourly O3 data, and predictor variables are developed using theoretically and empirically derived proxy regression variables. The regression model explains a significant proportion of the variation in the data (r2 = 0.54), with an average error of 7.1 ppb. When augmented with the areal mean, the r2 of the pre-interpolation model increases to 0.847. Model residuals are then spatially interpolated to the extents of the modeling domain. Final concentration estimate maps are the summation of areal mean, regression, and spatially interpolated surfaces, preserving absolute values at monitor locations.     

The Use of a Multimedia Risk Analysis Approach in Designing Waste Management Strategies

ABSTRACT

A pollution source may release residuals to any of several environmental media, depending on the process design and control strategies. These residuals then are subject to transfer, transport, and transformation within the interconnected compartments of the environmental system. The exposure and susceptibility of people and other receptors to pollutants are different in these various media, and so the risks imposed will vary according to the fate of the pollutants in the system. Because of interactions between compartments in the system, a single-medium approach to environmental management that mitigates problems in one environmental medium at a time independently of risks through other media may not minimize the aggregate risk a receptor receives from all pathways. Alternatively, a multimedia approach advocates focusing on the full environmental system providing pathways for exposure and selecting risk management strategies based on minimization of the aggregate and cumulative risk from all pathways and all compounds. This study combines multimedia risk analysis and an optimization framework to examine a methodology for selecting waste treatment/disposal and pollution control measures, applies the methodology to a sludge management decision problem, and considers the implications for continued use of single-medium analyses.