Modeling System Software Research Articles

Long-term health effects of early life exposure to tetrachloroethylene (PCE)-contaminated drinking water: a retrospective cohort study.

BackgroundWhile adult exposure to PCE is known to have toxic effects, there is little information on the long-term impact of prenatal and early childhood exposure. We undertook a retrospective cohort study to examine the effects of their early life exposure to PCE-contaminated drinking water. This retrospective cohort study examined whether prenatal and early childhood exposure to PCE-contaminated drinking water influenced the risk of a variety of chronic conditions among adults who were born between 1969 and 1983 in the Cape Cod area of Massachusetts.MethodsEight hundred and thirty-one participants with prenatal and early childhood PCE exposure and 547 unexposed participants were studied. Individuals completed questionnaires to gather information on demographic characteristics, chronic conditions, and other sources of solvent exposure. The location of residences from birth through 1990 were used to estimate PCE exposure with U.S. EPA’s water distribution system modeling software (EPANET) modified to incorporate a leaching and transport model.ResultsNo associations were observed between early life PCE exposure and current occurrence of obesity, diabetes, cardiovascular disease, hypertension, color blindness, near- and far sightedness and dry eyes. In contrast, a 1.8-fold increased risk of cancer (95% CI: 0.8, 4.0) was seen among individuals with any early life exposure. These results were based on 31 participants (23 exposed and 8 unexposed) who reported cancers at a variety of anatomical sites, particularly the cervix. A 1.5-fold increase in the risk of epilepsy (95% CI: 0.6, 3.6, based on 16 exposed and 7 unexposed participants) was also observed among individuals with any early life exposure that was further increased to 1.8 (95% CI: 0.7, 4.6) among those with exposure at or above the sample median.ConclusionsThese results suggest that the risk of epilepsy and certain types of cancer such as cervical cancer may be increased among adults who were exposed to PCE-contaminated drinking water exposure during gestation and early childhood. These findings should be interpreted cautiously because of the study limitations and confirmed in follow-up investigations of similarly exposed populations with medically-confirmed diagnoses. This relatively young study population should also be monitored periodically for subsequent changes in disease risk.

Hydrological analysis and flood mitigation at Wadi Hadramawt, Yemen

The current research aims at studying the runoff of Wadi Hadramawt employing mathematical models which comprise several methodologies. Moreover, flood damage mitigation structure was designed in accordance with the study outputs in order to mitigate flood risks. To achieve the research aims, data on precipitation, geological map, soil type, and land use were collected from the Yemen General Authority for Meteorology and Yemen Surveying Authority. A digital elevation model (DEM) is used for topographic maps. Frequency analysis techniques for maximum 25-, 50- and 100 years return period rainfall probability for Wadi Hadramawt were determined. The watershed modelling system (WMS) software package was used to delineate Wadi Hadramawt catchment and divide the catchment into eight sub-catchments. HEC-HMS software package was used to estimate the flood hydrographs for the eight sub-catchments. From the hydrological studies, dam structures at two sub-catchments were found essential to mitigate the flood risks in Hadramawt zone.

One- Dimensional Cutting Stock Problem in Al- Mansour Company

When short items are being cut out from long objects, the One- Dimensional Cutting Stock Problem (1D-CSP) is being appeared and caused increment in wastage material amounts, so the primary purpose of this paper is to use integer linear programming (ILP) based on Advance Interactive Mathematical Modeling System (AIMMS) software to minimize the trim losses which are resulting from one dimensional- long objects and also to reduce the total number of used stocks. Reinforcement Steel (Rebar) is used in building structure at Al-Aziziyah Housing Project by Al- Mansour Company as long objects with standard lengths and different diameters which are representing four problems according to these diameters (25 mm, 16 mm, 12 mm, and 10 mm). The implementation of that software is very effective to present optimal solutions, where the utilization stock ratio reached to (99.51%).

Fuzzy and stochastic mathematical programming for optimisation of cell formation problems in random and uncertain states

Applying mathematical programming models to solve the cellular manufacturing problems is a challenging task as decision makers find it difficult to specify goals and constraints because some of the involved parameters cannot be estimated precisely. This study presents a modelling approach for design of a dynamic cellular manufacturing system with uncertain characteristics and parameters. It provides mathematical models for solving cell formation problems (CFPs) in three different conditions: 1) crisp state in which all parameters are known and fixed; 2) fuzzy state in which setup cost, outsourcing cost and capacity of machines are considered as fuzzy parameters; 3) stochastic state in which probability distributions are used to model the assumed randomness. The general algebraic modelling system (GAMS) software is used to solve all test problems by CPLEX solver. This is the first study that presents mathematical programming models for solving CMS problems in crisp, stochastic and fuzzy states.

The Tourism Service Consumption Model for the Sustainability of the Special Protection Areas

Latvia can be described as a tourist-friendly country. The assumption is based on the statistical data of the ever increasing share of tourism services as a part of the GDP. The tendency of growth of the tourism sector comes with downsides which include an increasing pressure on the territories of special protection area status. The goal of the research is to create a tourism service consumption model that can be used as a tool for sustainable management of the special protection areas (SPAs) while reaching the present and future needs in an efficient way. The model was created with the system modeling software STELLA and based on the acknowledged data of the Slitere National Park tourism resources, the monitoring data from the period of 2009 till 2011, and on the local and international experience and methods for determining the capacity of national parks. When comparing acquired data from software STELLA and Excel, tourism service consumption model validity was ascertained with a result of 0.98 and the credibility – 0.97. The input data is changeable; the platform is lucid and widely usable also in future.

Research on Mixer Parametric Modeling System Based on Redevelopment of ANSYS

In this paper, the mixer parametric modeling system software was developed by using VB which was taken as the foreground development program, and the paper combined with ANSYS software to create the finite element model of mixer blade and cylinder for the following numerical simulation of the flow field and parameter optimization of mixer. The software user interface was developed by VB and the pre-process model was created by invoking APDL of ANSYS in background. Therefore, the operation of modeling, meshing, component-building of mixer blade and cylinder were completed by using APDL and the graphic and text were outputted and displayed on the mixer parametric modeling system user interface which was developed by VB. Practice proved that it is convenient to modify the mixer solid model created by the parametric design language of ANSYS due to the similar structure.

Prenatal drinking-water exposure to tetrachloroethylene and ischemic placental disease: a retrospective cohort study.

BackgroundPrenatal drinking water exposure to tetrachloroethylene (PCE) has been previously related to intrauterine growth restriction and stillbirth. Pathophysiologic and epidemiologic evidence linking these outcomes to certain other pregnancy complications, including placental abruption, preeclampsia, and small-for-gestational-age (SGA) (i.e., ischemic placental diseases), suggests that PCE exposure may also be associated with these events. We examined whether prenatal exposure to PCE-contaminated drinking water was associated with overall or individual ischemic placental diseases.MethodsUsing a retrospective cohort design, we compared 1,091 PCE-exposed and 1,019 unexposed pregnancies from 1,766 Cape Cod, Massachusetts women. Exposure between 1969 and 1990 was estimated using water distribution system modeling software. Data on birth weight and gestational age were obtained from birth certificates; mothers self-reported pregnancy complications.ResultsOf 2,110 eligible pregnancies, 9% (N = 196) were complicated by ≥1 ischemic placental disease. PCE exposure was not associated with overall ischemic placental disease (for PCE ≥ sample median vs. no exposure, risk ratio (RR): 0.90; 95% confidence interval (CI): 0.65, 1.24), preeclampsia (RR: 0.36; 95% CI: 0.12-1.07), or SGA (RR: 0.98; 95% CI: 0.66-1.45). However, pregnancies with PCE exposure ≥ the sample median had 2.38-times the risk of stillbirth ≥27 weeks gestation (95% CI: 1.01, 5.59), and 1.35-times of the risk of placental abruption (95% CI: 0.68, 2.67) relative to unexposed pregnancies.ConclusionsPrenatal PCE exposure was not associated with overall ischemic placental disease, but may increase risk of stillbirth.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-069X-13-72) contains supplementary material, which is available to authorized users.

Capacity optimization and scheduling of a multiproduct manufacturing facility for biotech products.

A general mathematical framework has been proposed in this work for scheduling of a multiproduct and multipurpose facility involving manufacturing of biotech products. The specific problem involves several batch operations occurring in multiple units involving fixed processing time, unlimited storage policy, transition times, shared units, and deterministic and fixed data in the given time horizon. The different batch operations are modeled using state-task network representation. Two different mathematical formulations are proposed based on discrete- and continuous-time representations leading to a mixed-integer linear programming model which is solved using General Algebraic Modeling System software. A case study based on a real facility is presented to illustrate the potential and applicability of the proposed models. The continuous-time model required less number of events and has a smaller problem size compared to the discrete-time model.

Employing demand response in energy procurement plans of electricity retailers

This paper proposes a new framework in which demand response (DR) is incorporated as an energy resource of electricity retailers in addition to the commonly used forward contracts and pool markets. In this way, a stepwise reward-based DR is proposed as a real-time resource of the retailer. In addition, the unpredictable behavior of customers participating in the proposed reward-based DR is modeled through a scenario-based participation factor. The overall problem is formulated as a stochastic optimization approach in which pool prices and customers’ participation in DR are uncertain variables. The feasibility of the problem is evaluated on a realistic case of the Australian National Electricity Market (NEM) and solved using General Algebraic Modeling System (GAMS) software.

Nonlinear programming optimization of series and parallel cyclone arrangement of NPK fertilizer plants

The gas–solid cyclone has been remarkably widely used among all types of industrial gas-cleaning devices. The objective of this work was to present the nonlinear optimization modeling of series and parallel cyclone arrangement for 1D3D, 2D2D and 1D2D cyclones of the Nitrogen, Phosphorus, and Potassium (NPK) fertilizer plant. The numerical solutions were carried out using the General Algebraic Modeling System (GAMS) software for different case studies. The optimal number of cyclone with the minimum total cost for two types of arrangements was obtained. From the economic point of view, the results of mathematical programming models showed that the small cyclone with a small number of the cyclone arrangement could be implemented for space-limited conditions on the field, and the pressure drop across the cyclone was directly related to the fan power requirement.

Application of multi-methods in the calculation and validation of aquifer parameters in Longkeng water source area in Songyuan City, China

To obtain more accurate hydrogeological parameters of an aquifer, multi-methods are applied in this paper. Taking the Longkeng water source in Songyuan City as an example, a pumping test, as well as the groundwater dynamical, spring discharge inverse, and groundwater hydrochemical kinetics method are first applied to determine the hydrogeological parameters of the aquifer in this area. Groundwater numerical simulating models are then built using Groundwater Modeling System software to identify and certify the parameters. According to the all-time water-level fitting curve of long-term observation wells, the relative error of simulated water level is less than 6 %. According to these methods, the parameters for the whole region are obtained, and these parameters are more accurate than those obtained by using pumping tests alone.

Promoting sustainable infrastructure: a feasibility analysis of a utility-scale PV covered parking structure

The growing demand for clean electricity production is driven by increased energy consumption, electricity rate volatility, and environmental policy changes that reflect a change in consumer preferences. The need for a more sustainable society presents a unique opportunity for educational institutions to help facilitate this change with the construction of environmentally friendly energy producing systems. The purpose of this research is to assess the feasibility of a utility-scale photovoltaic (PV) electricity generation system on Illinois State University's (ISU) campus. The potential power production from the PV system can be estimated through analysis of the climate information and utilising PV system modeling software. In this feasibility analysis, eight utility-scale PV systems were modeled and simulated to determine three optimal systems for the university. Implementing clean energy systems into educational institutions will also increase the general public's awareness about the societal shift towa...

Spillways Scheduling for Flood Control of Three Gorges Reservoir Using Mixed Integer Linear Programming Model

This study proposes a mixed integer linear programming (MILP) model to optimize the spillways scheduling for reservoir flood control. Unlike the conventional reservoir operation model, the proposed MILP model specifies the spillways status (including the number of spillways to be open and the degree of the spillway opened) instead of reservoir release, since the release is actually controlled by using the spillway. The piecewise linear approximation is used to formulate the relationship between the reservoir storage and water release for a spillway, which should be open/closed with a status depicted by a binary variable. The control order and symmetry rules of spillways are described and incorporated into the constraints for meeting the practical demand. Thus, a MILP model is set up to minimize the maximum reservoir storage. The General Algebraic Modeling System (GAMS) and IBM ILOG CPLEX Optimization Studio (CPLEX) software are used to find the optimal solution for the proposed MILP model. The China’s Three Gorges Reservoir, whose spillways are of five types with the total number of 80, is selected as the case study. It is shown that the proposed model decreases the flood risk compared with the conventional operation and makes the operation more practical by specifying the spillways status directly.

Simplified formulae for the estimation of offshore wind turbines clutter on marine radars.

The potential impact that offshore wind farms may cause on nearby marine radars should be considered before the wind farm is installed. Strong radar echoes from the turbines may degrade radars' detection capability in the area around the wind farm. Although conventional computational methods provide accurate results of scattering by wind turbines, they are not directly implementable in software tools that can be used to conduct the impact studies. This paper proposes a simple model to assess the clutter that wind turbines may generate on marine radars. This method can be easily implemented in the system modeling software tools for the impact analysis of a wind farm in a real scenario.

Advances in CSP Simulation Technology in the System Advisor Model

The System Advisor Model (SAM) is modeling software for renewable energy systems developed by the National Renewable Energy Laboratory (NREL).SAM combines annual time series power production models with financial models to estimate the levelized cost of energy (LCOE) and other metrics for renewable energy projects. To date, SAM has utilized the general purpose commercial TRNSYS transient systems modeling software package for CSP simulations and originally PV and wind. To achieve: (1) significantly faster model performance, (2) easy parallelization of concurrent simulations to take advantage of modern multi-core processor desktop computers, (3) to allow straightforward modification of CSP component models in the SAM environment, and (4) ability to include CSP technologies in the SAM Software Development Kit (SDK), NREL has undertaken to reformulate the CSP models into a new transient simulation framework written in C++, by NREL. This framework is tailored specifically for use in SAM and not for general purpose modeling like TRNSYS. Preliminary results show excellent matching with the accepted TRNSYS-based models, as well as an order of magnitude reduction in simulation time for certain models. These runtime reductions enable larger scale plant configuration analysis, as well as grid-integration studies that require many thousands of simulations.

Heating and cooling in high-rise buildings using facade-integrated transparent solar thermal collector systems

New facades of high-rise buildings often include renewable energy converters to allow “green building” operation. At the same time, numerous tenants value visual transparency. Transparent solar thermal collectors (TSTCs) aim at decreasing the non-renewable primary energy demand and increasing the visual transparency at the same time. On the one hand, this paper presents the main modelling challenges that arise when considering building facades and especially integrated TSTC systems. New transient systems simulation (TRNSYS) [Beckman, W. A., L. Broman, A. Fiksel, S. A. Klein, E. Lindberg, M. Schuler, and J. Thornton. 1994. “TRNSYS The Most Complete Solar Energy System Modelling and Simulation Software.” Renewable Energy 5 (1–4): 486–488] types have been especially developed for this purpose. A simplified model is presented for comparison purposes. On the other hand, the overall performance for a building with facade-integrated TSTC, as measured by its non-renewable primary energy demand, is treated. This is achieved by considering a complete simulation model coupling the TSTC, building and heating, ventilation and air conditioning operation. Possibilities for primary energy savings are investigated using the building mass as additional thermal storage.

Fracture modelling based on the stochastic extended finite element method

Because a large number of oil and gas reservoirs are naturally fractured, they play an important role in hydrocarbon exploration and production. To fully extract and model the fracture system features of reservoirs, a new fracture modelling method, called the stochastic extended finite element (SEFE) method, is presented in this paper. This method couples fracture mechanics and the kriging method with a multi-field trend in an attempt to benefit from the advantages of each method: compliance with fracture mechanics equations and the reproduction of the fracture’s observed data, respectively. Based on the SEFE simulation method, we wrote a fracture modelling system software and built a fracture propagation model and a fracture distribution model of the Upper Cretaceous Formation in the Daqingzi region. A parallel study was performed to verify the fracture propagation pattern and boundary conditions in the proposed model based on a geomechanical analogue experiment. The results of these studies demonstrate that fracture modelling based on the SEFE method may improve the precise characterization of fractured reservoirs.

Groundwater flow model of the Pipiripau watershed, Federal District of Brazil

In order to understand the groundwater dynamics and to improve the management of water resources in the Federal District of Brazil, this research proposes a 3D groundwater flow model to represent the groundwater level and flow system. The selected test site was the Pipiripau catchment. The development of the model was based on available geological, hydrogeological, geomorphological, climatological and pedological data. Geological and hydrogeological data were used to generate the 3D groundwater flow model. The 3D mesh elements of the domain were generated through the Groundwater Modeling System software, based on the logs of the well materials. The numerical simulation of the finite element method was implemented in the framework of the scientific software OpenGeoSys. With the 3D mesh-appropriated boundary conditions, annual average infiltration data and hydrogeological parameters were incorporated. Afterwards, the steady-state model was calibrated by the PEST software using available data of the water level from wells. The results showed the distribution of the steady-state hydraulic heads in the model domain, where the highest values occurred in the east and west recharge areas and the lowest values were found in the southwest of the basin. The results of this study can be a used as initial condition for the transient groundwater flow simulation and to provide a scientific basis for water resource management.

A new river system modelling tool for sustainable operational management of water resources

The eWater Cooperative Research Centre of Australia has developed a river system modelling software called eWater Source that can be used to assist water managers and river operators in planning and operating river systems. It has been designed and developed within Australia to provide a consistent approach to underpin a wide range of water planning and management purposes. The software provides tools for the prediction and quantification of water from catchments to the end of a river system by integrating continuous rainfall-runoff and river system models. It includes three modes (catchment runoff, river management and river operations) for different applications. This paper introduces the operations mode of Source and compares its functionality with the existing tools used for daily river operations in Australia, with the Goulburn River as the case study. A 5-year period is used to compare modelled and observed results. Forecasts from Source and the existing tools are compared to observations over 7-day forecast periods that include an environmental water release. Source provided acceptable or improved results and required less user input than the existing method. Source provides a flexible software tool in which various forecast models can be incorporated. The application has demonstrated the potential of Source to provide an improvement on the existing river operations models in Australia at both the daily and seasonal time steps.

Application of spaceborne synthetic aperture radar data for extraction of soil moisture and its use in hydrological modelling at Gottleuba Catchment, Saxony, Germany

AbstractHydrological modelling is a powerful tool for hydrologists and engineers involved in the planning and management of water resources. With the recent advent of computational power and the growing availability of spatial data, remote sensing and geographical information systems technologies can augment to a great extent the conventional methods used in rainfall run‐off studies. That means it is possible to accurately describe the characteristics of watershed in particularly when determining the run‐off response to rainfall inputs. The main objective of this study is to apply the potential application of spaceborne synthetic aperture radar (SAR) data (i.e. TerraSAR‐X and Advanced Land Observing Satellite/Phased Array type L‐band Synthetic Aperture Radar (ALOS PALSAR) for soil moisture retrieval) and to improve the spatial input parameters required for hydrological modelling. For the spatial database creation, a high‐resolution 2‐m aerial laser scanning digital terrain model, soil map, and land use map were used. Rainfall records were transformed into a run‐off through hydrological parameterisation of the watershed using Hydrologic Engineering Center's Hydrologic Modelling System (HEC‐HMS) software for rainfall run‐off simulation. The Soil Conservation Services Curve Number and soil moisture accounting loss methods were selected to calculate the infiltration losses. In this research, soil moisture was derived from two different types of spaceborne SAR data: TerraSAR‐X and ALOS PALSAR (L‐band). The developed integrated hydrological model was applied to a flood prone area: Gottleuba Catchment in Pirna (Saxony, Germany). For model validation, 10 years historical precipitation data were used. The validated model was further optimised using the extracted soil moisture from SAR data. The simulation results showed a reasonable match between the simulated and the observed hydrographs. Hence, this paper confirms that TerraSAR‐X and ALOS PALSAR (L‐band) have a high potential for soil moisture mapping as a useful source of information and technique in hydrological modelling.