Simulation modelling

Paper presents analysis of the order picking system efficiency under congestion situations. Analysed picking system is manual and organized as picker-to-part system with very narrow aisles. About 150 different variants of the system was taken into consideration. Each of them is characterized by different storage policies (random, class-based and volume-based), number of order pickers and picking strategies (single picking and batch picking). Main attention was paid to picker blocking phenomenon and its impact on order picking efficiency. Authors explain where, when and why such situations may happen. Additionally, they point out how the number of pickers, storage policy and picking strategy impact pickers blocking and picking process efficiency. Due to complexity of presented issue, dynamics and volatility of picking processes, simulation method was implemented.

Inventory replenishment rules have been recognized as a major cause of the bullwhip effect and inventory instability in multi-echelon supply chains. There is a trade-off between bullwhip effect and inventory stability where mitigating the bullwhip effect through order smoothing might increase inventory instability. Therefore, there is a substantial need for inventory control policies that can cope with supply chains dynamics. This paper attempts to formulate an inventory control system based on a statistical control chart approach to handle the trade-off between order variability amplification and inventory stability. The proposed replenishment system, namely IR-SPC, incorporates individual control charts to control both the inventory position and the placed orders. A simulation study has been conducted to evaluate and compare the IR-SPC with a generalized order-up-to that has order smoothing mechanism. The comparisons showed that the IR-SPC outperforms both the smoothing order-up-to policy and the Min-Max inventory policy in terms of bullwhip effect and inventory performances.

technologies along soil fertility gradients, relying on local indicators to differentiate those that may be managed through 'maintenance fertilization' from fields that are highly-responsive to fertilizers and fields that require rehabilitation before yields can improved. Where human population pressure on the land is less intense, farm and field types are harder to discern, without clear patterns. Nutrient cycling through livestock is in principle not efficient for increasing food production due to increased nutrient losses, but is attractive for farmers due to the multiple functions of livestock. We identified trade-offs between income generation, soil conservation and community agreements through optimising concurrent objectives at farm and village levels. These examples show that future analyses must focus at farm and farming system level and not at the level of individual fields to achieve appropriate targeting of technologies -both between locations and between farms at any given location. The approach for integrated assessment described here can be used ex ante to explore the potential of best-fit technologies and the ways they can be best combined at farm level. The dynamic and integrated nature of the framework allows the impact of changes in external drivers such as climate change or development policy to be analysed. Fundamental questions for integrated analysis relate to the site-specific knowledge and the simplification of processes required to integrate and move from one level to the next.

Analysis of Electric Circuit Model on Atmospheric Pressure Dielectric Barrier Discharge (DBD) Plasma has been simulated using the Simulink-Matlab R2010a software. Plasma reactor being used as the basis to determine the parameters in the circuit is in the coaxial form made of pyrex glass with an iron rod as the active electrode and spiral copper wire as passive electrode. The reactor was filled with argon gas with the flow rate of 2 L/s. Simulation circuit model which was prepared based on a DBD equivalent circuit, operated in a voltage range of 1.0 kV to 6.0 kV for frequency of 10 kHz to 66 kHz. Electrical characterization was performed to describe the plasma discharge that occurs in the reactor. The datas of supply voltage and current, as well as voltage and current discharge, was used to determine the average power during one period. From the simulation was obtained an increase in supply and discharge currents with increasing of frequency at the same operating voltage. Discharge power has increased in a specific voltage and increased frequency. It is obtained the average discharge power for 5.5 kV of 11.28 W and 10.90 W at a frequency of 21 kHz and 24 kHz, respectively. The highest efficiency obtained from the simulation that achieved at voltage of 1 kV and frequency of 45.7 kHz is equal to 56.59%.

Traffic models play an important role in both today's traffic research and in many traffic applications such as traffic flow prediction, incident detection and traffic control. Modelling traffic dynamics and optimising the control signal are two interrelated problems. Modelling provides fundamental understanding of traffic dynamics and behaviour. In this paper, traffic signal is modelled as a M/M/l queueing theory. The validation of a simulation model (M/M/l queue) with different arrival rates is presented. From the result, a traffic light model was developed by applying M/M/l queue theory for single intersection. In the optimisation strategy, the Markov decision control is applied to minimize queue length and waiting time. Simulation results show the excellent potential of this approach

Microscopic simulation modelling has recently become attractive to researchers in traffic engineering as it appears to offer a cost effective and 'safe' way of investigating Intelligent Vehicle-Highway System (IVHS) at a fundamental level. However, the deterministic approach used assumes a consistency of behaviour which may severely detract from model validity. This may be overcome by using a 'fuzzy' approach to describe drivers' decisions.

In recent years, the topic of car-following has become of increased importance in trac engineering and safety research. Models of this phenomenon, which describe the interaction between (typically) adjacent vehicles in the same lane, now form the cornerstone for many important areas of research including (a) simulation modelling, where the car-following model (amongst others) controls the motion of the vehicles in the network, and (b) the functional de®nition of advanced vehicle control and safety systems (AVCSS), which are being introduced as a driver safety aid in an eort to mimic driver behaviour but remove human error. Despite the importance of this area however, no overview of the models availability and validity exists. It is the intent of this paper therefore to brie¯y assess the range of options available in the choice of car-following model, and assess just how far work has proceeded in our understanding of what, at times, would appear to be a simple process. Ó

... Teknologi Malaysia, 81310, Skudai, Johor, Malaysia [email protected], [email protected], [email protected] ... but a better trade-off among these parameters can be achieved in active suspension system, Taghirad and Esmailzadeh [2]. Many ...

The method of Lohrenz-Bray-Clark, which relates the residual viscosity to the reduced density, is the most widely used engineering tool to predict the viscosity of reservoir uids. Systematic investigation of the viscosity of pure compounds at various pressure and temperature conditions indicated the requirement of including the structural and thermal e ects for accurate viscosity prediction of dense uids. The method has been modiÿed to include the above-mentioned e ects. Reliability of the modiÿed method for calculating viscosity of mixtures and in particular of high-pressure high-temperature uids has been demonstrated. ?

CA = Cellular Automata LR = Literature Review AM = Analyse available urban CA Models EI = Expert Interview TP =Transition Potential of cell NB =Neighbourhood Effect AC =Accessibility Effect SU =Suitability Effect PL =Planning Influence SEco =Social-Economic influence TR =Transition Rule TPR =Transition Potential Rule CRR =Confliction Resolving Rule

The focus on supply chain management has increased in recent years; among academics as well as among practitioners. In this paper, we present a supply chain simulation study for a real case, concerned with the manufacturing of mobile communication systems. The purpose of the study is twofold. One objective is to evaluate alternative supply chain designs with respect to quality, lead-times and costs as the key performance parameters. A second objective is to increase the understanding of the interrelationships among these and other parameters, relevant for the design of the supply chain structure. The design alternatives di!er in terms of the level of integration and synchronisation between supply chain stages. Modelling and validation issues are highlighted since these are fundamental to a supply chain simulation study. The results are discussed and a model capturing the relationships among cost, quality, and lead-times, based on the simulation study, is presented.

Volume 23, Issue 2, Pages 87-172 (February 2005) 10. Harrison, Frederick, Lock, Dennis, Advanced project management -a structured approach fourth ed., Gower Publishing Limited; 2004, 315 pages, ISBN 0-566-07822-8, £67.50. Pages 169-171 Garth G.F. Ward 11. Alan Webb. The Project Manager's guide to Handling Risk. Gower, Aldershot, 2003, Hardbound 179 pp. £55.00, ISBN 0 566-08571-2. Page 172 Steve Simister

The absorption of NO x into pure water or nitric acid is usually a kinetically controlled operation in which complex reactions in both gas and liquid phases are combined with multicomponent mass transfer. To be able to describe this process adequately, a rigorous general rate-based model for the reactive absorption in tray and packed columns has been developed based on earlier works (see, e.g. [Kenig et al., 2001. Chemical Engineering Science 56, 343-350; Kenig et al., 2003. Chemical Engineering and Technology 6, 631-646]). Heat and multicomponent mass transfer in the film phases, chemical reactions and thermodynamic non-idealities are taken into account. Furthermore, the influence of column internals and hydraulics is considered via relevant correlations. For tray columns, a special consideration of the empty sections above the gas-liquid layer on a tray is included. The model is implemented into the simulation environment Aspen Custom Modeler TM and validated by comparison with experimental data for a pilot scale packed column and an industrial sieve tray column equipped with cooling coils. The simulation results obtained for both column types agree well with the experimental measurements. In addition, the influence of cooling on the process behaviour is studied.

This paper describes a digital proportional-integral-derivative (PID) controller technique applied to the DC-DC buck converter. The converter is modelled using a state space averaging technique. Due to the non-linear of the power converter, the PID controller is designed to simplify the compensation of the DC-DC converter. The control algorithm is implemented in digital signal processor (DSP) TMS320F2812. The steady state and dynamic response performances of the controller are demonstrated. Experimental results are provided to demonstrate the effectiveness of the design.

A practical application of the modelling and validation of an open-chain industrial manipulator is presented in this paper. Both mechanical and electrical equations of motion were used to provide a complete model description. A model was obtained to enable an optimal pathplanning controller to be designed. The paper describes how the equations of motion were derived and how the key parameters were obtained. The manipulator was simulated with TELEGRIP software. A validation procedure is illustrated and its' limitations exposed. The overall motion was found to give an agreement with the model predictions to within 86% for the smallest link and better than 96% for the major joints. Ó

Different approaches for lifetime prediction for electrochemical energy storage devices are discussed with respect to their general concepts. Examples for their implementation and advantages and disadvantages are given. The models are based on: (a) physical and chemical processes and their interaction as regards ageing effects; (b) weighting of the Ah throughput whenever the operating conditions deviate from the standard conditions used for determining the lifetime under laboratory conditions; (c) an event-oriented concept from mechanical engineering (Wöhler curves) which is based on a pattern recognition approach to identify severe operating conditions.

Laser welding is a high power density welding technology, which has the capability of focusing the beam power to a very small spot diameter. Its characteristics such as high precision and low and concentrated heat input, helps in minimizing the micro-structural modifications, residual stresses and distortions on the welded specimens. In this study, finite element method (FEM) is adopted for predicting the bead geometry in laser welding of 1.6 mm thick AISI304 stainless steel sheets. A three-dimensional finite element model is used to analyze the temperature distribution in a T-joint weld produced by the laser welding process. Temperature-dependent thermal properties of AISI304 stainless steel, effect of latent heat of fusion, and the convective and radiative boundary conditions are included in the model. The heat input to the model is assumed to be a 3D conical Gaussian heat source. The finite element code SYSWELD, along with a few FORTRAN subroutines, is employed to obtain the numerical results. The T-joint welds are made using a Nd:YAG laser having a maximum power of 2 kW in the continuous wave mode. The effect of laser beam power, welding speed and beam incident angle on the weld bead geometry (i.e. depth of penetration and bead width) are investigated. Finally, the shapes of the molten pool predicted by the numerical analysis are compared with the results obtained through the experimentation. The comparison shows that they are in good agreement.

available online at http://meteoritics.org 247 Abstract-Understanding the nature and composition of larger extraterrestrial bodies that may collide with the Earth is important. One source of information lies in the record of ancient impact craters, some of which have yielded chemical information as to the impacting body. Many deeply eroded craters have no remaining melt sheet or ejecta yet may contain impactor residue within basement fractures. The emplacement mechanism for fractionated siderophile residues is likely to be gaseous, although, melt droplets and some solid materials may survive. For breccia-and melt-filled fractures to contain extraterrestrial material, they must form very early in the impact process. Most current numerical models do not dwell on the formation and location of early major fractures, although, fractures in and around small craters on brittle glass exposed to hypervelocity impact in low Earth orbit have been successfully simulated. Modelling of fracture development associated with larger craters may help locate impact residues and test the models themselves.

The current quality assurance and control tools and methods to prevent and/or to control microbiological risks associated with fresh produce are challenged due to the following pressures upon the food supply chain, i.e. changing consumption patterns, globalization and climate change. It demonstrates the need for scientific research and development of new and/or improved tools, techniques and practices to adapt the current risk management systems. In this paper, a conceptual research approach is presented to analyse the complexity of the climate change and globalization challenge on the fresh produce supply chain taken as a case study. The factors which affect the vulnerability of the fresh produce chain demand a multidisciplinary research approach. The proposed knowledge-based modelling system is believed to be a most appropriate way to identify problems and to offer solutions to monitor and prevent microbiological food safety risks during all phases of food production and supply. To explore the potential impact of climate change and globalization, baseline information can be obtained by surveillance and performance measurement of implemented food safety management systems. Simulation of climate change scenarios and the logistic chain of fresh produce, along with mathematical models to optimize packaging technology to maintain quality and safety of fresh produce are tools to provide insights in the complex dynamic ecosystem. They are the basis for elaboration of risk assessment studies to scientifically support management options and decisions to new microbiological threats related to globalization and climate change in the fresh produce supply chain. This research concept as such will contribute to develop strategies in order to guarantee the (microbiological) food safety of fresh produce on the long term.

The case for integrating research methods generally, and more specifically that for combining system dynamics modelling and case study research approaches is strong. Yet, research designs that extensively combine both system dynamics modelling and case study in requirements engineering process modelling are rare. Triangulation of methods while not new, has not been applied in requirements engineering process modelling and improvement research. This paper aims to provide a useful and systematic reference point for researchers who wish to work in the RE process improvement and generally to encourage careful work on the conceptualisation and execution of Dynamic Synthesis methodology in RE process and to a wider software process modelling field. The paper addresses the philosophical and theoretical issues concerning the nature of combining the case study and process simulation research approaches, and methodological issues on conduct and reporting of this type of research design. The paper suggests that the potential usefulness of the Dynamic Synthesis Methodology is in aiding researchers in improving both building and testing theories in the requirements engineering process modelling and improvement.

A hospital's emergency department (ED) is responsible to treat patients in an immediate and fastest response as possible. However, the ED management faces greater challenge with patients overcrowd caused by long waiting time for each patient to receive treatment and eventually increased each patient's length of stay in the ED area. Any wrong decision made to overcome this problem may lead to a more serious problem in the future. This study presents a proposed simulation model framework to analyse the actual operation in an ED of a public hospital in Malaysia. The model is able to help the ED management to better understand daily operations of the department and how it affected by the level of resource capacity.

In most regions of the world removal of environmental stress facilitates regeneration of native plants and habitats. However, in many of New Zealand's modified landscapes, exotic species are likely to respond first to any reduction in stress because these fast-growing species are prevalent in local vegetation and dominate seed banks. Given the trend in agriculture towards intensive management on larger units, the indigenous character in New Zealand landscapes is being marginalised and there is the risk that further reduction in visibility of native vegetation may be perpetuated by a growing familiarity and identification with ubiquitous exotic species. Alternative landscapes, based on an understanding of ecosystem processes, need to be explored if biodiversity goals set by international convention and national resource management law are to be achieved. This study provides a set of predictions and pathways, backed by field observations, to underpin a restoration strategy at pat...

By means of carefully devised assumptions, a simple linear model is presented for an absorption refrigeration unit employing either water-lithium bromide or ammonia-water refrigerant-absorbent pairs. Absorption systems are an alternative to vapour compression systems by being thermally activated. Such heat energy may come from the sun or even from hot exhaust gases from a particular engineering process. A thorough investigation of the optimal operating temperatures is necessary to ensure effective operation of the system. By means of this simulation, the system response to varying absorber, generator and condenser temperatures was analyzed.

A process-based crop growth model is developed to predict regional crop yield, water consumption and water use efficiency (WUE) using remotely sensed data for a portion of Hebei province (88 779 km 2 ), most of which is located on the North China Plain (NCP). Model inputs consist of Geographic Information System (GIS) maps of land use, Digital Elevation Model (DEM), soil texture, crop canopy leaf area index (LAI) which is retrieved from the 10-day maximum composite National Oceanic and Atmospheric Administration (NOAA)-Advanced Very High Resolution Radiometer (AVHRR) data, and daily interpolated meteorological variables. The model is run at 92 367 30 × 30 . resolution grids at an hourly time-step for energy balance and daily time-step for crop growth simulation. Simulated winter wheat and summer maize yields in 1992 and 1993 are compared with both the point samples and the county-level census data. For the 108 counties, the root mean square error (relative deviation) is 1124 kg ha −1 (23%) for winter wheat and 1359 kg ha −1 (33%) for summer maize, respectively. Spatial patterns of simulated crop yield and water use efficiency are strongly influenced by irrigated/rainfed conditions. The modelled grain yield for irrigated winter wheat ranges from 3900 to 7200 kg ha −1 , which is significantly larger than when only rainfed, 100-2600 kg ha −1 . The modelled grain yield for irrigated maize ranges from 5800 to 8600 kg ha −1 , which is significantly larger than when only rainfed, 1400-4800 kg ha −1 . This suggests that the potential exists to increase yield in this region, if sufficient irrigation water is supplied. However, given the over allocation of limited surface water, an increase in irrigation is unlikely, and increasing importance will be placed on maximizing regional WUE over the NCP. The water consumption (defined here as modelled evapotranspiration (ET)) for winter wheat ranges from 330 to 500 and 70 to 280 mm for irrigated and rainfed conditions, respectively. The modelled ET for irrigated maize ranges from 350 to 520, and 140 to 350 mm for rainfed conditions. The simulated WUE simulated WUE ranges from 11 to 19.25 kg ha −1 mm −1 for irrigated maize and from 5 to 11 kg ha −1 mm −1 in rainfed areas.

Purpose: Business renovation, the effective utilisation of information technology and the role of business process modelling and simulation are all vital in supply chain integration projects. The main idea is to show through a combination of these methods how the performance of the supply chain can be improved with the renovation and integration of processes at various tiers in the chain and by the sharing of information between companies. Methodology/Approach: Simulation-based methodology for measuring the benefits of the creation and renovation of business process models combines the methodology of developing process models and its simulation with the simulation of supply and demand. A procurement process in the oil/retail petrol industry is examined in a case study. Findings: Using the proposed methodology, different business process models can be investigated and simulated. The benefits for each company involved in the presented case are substantial and can be estimated through a simulation. Substantial benefits in costs, quality and lead times were identified, however, their distribution is not symmetric. Interorganisational IS and applied technology were enablers for supply chain integration. However, organisational changes and new business models were prerequisites for obtaining those benefits. Practical implications: The process approach to supply chain integration presents a mechanism that can be applied to any industry. It represents a systematic methodological business renovation approach involving cost cuts, quality improvements and lead time improvements. The costs of supply chain integration projects were not studied. The benefits should be measured against the cost of testing the economic feasibility of such projects. Originality/value of paper: The effective utilisation of business process modelling and a simulation of the necessary business renovation is shown. The novel combination of business process and demand/supply simulation enables an estimation of changes in lead-times, process execution costs, quality of the process and inventory costs. Although the methodology is presented through a case study of the oil/retail petrol industry, it can also be used to estimate the benefits and monitor supply chain integration projects in other industries.

In this review we argue that theories and methodology arising from the field of complex systems form a new paradigm for ecology. Patterns and processes resulting from interactions between individuals, populations, species and communities in landscapes are the core topic of ecology. These interactions form complex networks, which are the subject of intense research in complexity theory, informatics and statistical mechanics. This research has shown that complex natural networks often share common structures such as loops, trees and clusters. The observed structures contribute to widespread processes including feedback, non-linear dynamics, criticality and self-organisation. Simulation modelling is a key tool in studying complex networks and has become popular in ecology, especially in adaptive management. Important techniques include cellular automata and individual-based models. The complex systems paradigm has led to advances in landscape ecology, including a deeper understanding of the dynamics of spatial pattern formation, habitat fragmentation, epidemic processes, and genetic variation. Network analysis reveals that underlying patterns of interactions, such as small worlds and clusters, in food webs and ecosystems have strong implications for their stability and dynamics. These investigations illustrate how complexity theory and associated methodologies are transforming ecological research, providing new perspectives on old questions as well as raising many new ones. #

In this paper, a Multi-Criteria Scheduling Algorithm (MCSA) based on swapping of dispatching rules and Selective Rerouting (SR) approach based on lateral entry of critical jobs in the queue of alternate machine is used. Further, the effect of simultaneous application of MCSA and SR has been investigated. The system performance has been evaluated using mean flow time, maximum flow time, mean tardiness and maximum tardiness as the performance measures. Simulation studies using ProModel ® simulation software were carried out at different breakdown levels for a range of part complexity and part mix, in three types of flexible job shops with Job/Machine ratio less than, equal to and greater than unity involving a total of 799 simulation runs. Each run of simulation spans for a period of 2000 completed jobs. The results establish that simultaneous application of MCSA and SR improves the system performance between 12.17 % to 28.73 % and 30.51 % to 47.67 % over that when SR and MCSA respectively are applied individually. The improvement is more at low breakdown levels and high part complexity.

Current development plans indicate that during the next decade there will be an increase in tidal stream and wave (TSW) power generation activity in Scottish Waters, together with the designation of additional offshore areas for seabird conservation. This paper summarises how TSW developments could affect seabirds, based on experience from other forms of disturbance, and explores the possible changes in behaviour and habitat that have the potential to increase a seabird's rate of energy acquisition (e.g. through enhancing prey abundance), or energy expenditure (e.g. through causing birds to commute further to find food, if they avoid foraging around developments placed in regular feeding areas). Changes to energy budgets could impact rates of reproduction and survival. Simulation modelling of seabird energetics and behaviour is one possible tool for predicting the direction and magnitude of population impacts caused by alterations to energy budgets, but is dependant on the availability and accuracy of necessary parameters. The later sections of the paper review the information needed for such models and shows that although some data are available regarding rates of energy expenditure during specific activities, more information is needed on seabird foraging rates. The paper also highlights how the susceptibility of a species to be impacted by future TSW development is likely to be related to their method of foraging, flight behaviour and ability to buffer against environmental fluctuations.

In the last two decades traditional cost accounting practices have been unable to respond to the changing information needs of manufacturing management. Activity Based Costing (ABC) is a method which can solve many of the limitations of traditional cost systems. This method of accounting involves the breaking down of the individual activities and costing of the amount of time spent on each step of the manufacture of a product. This paper illustrates how Discrete Event Simulation may be used to evaluate the ABC of a manufacturing system. A visual interactive simulation software WITNESS is used to model a semi-automated Printed Circuit Board (PCB) assembly line. The PCB assembly line case study demonstrates how ABC can be applied to a manufacturing system using simulation modelling techniques. The paper also discusses further applications of ABC in the manufacturing environment and includes a case study on the operational quality cost.

There is a pressing need to improve the water-use efficiency of rain-fed and irrigated crop production. Breeding crop varieties with higher water-use efficiency is seen as providing part of the solution. Three key processes can be exploited in breeding for high wateruse efficiency: (i) moving more of the available water through the crop rather than it being wasted as evaporation from the soil surface or drainage beyond the root zone or being left behind in the root zone at harvest; (ii) acquiring more carbon (biomass) in exchange for the water transpired by the crop, i.e. improving crop transpiration efficiency; (iii) partitioning more of the achieved biomass into the harvested product. The relative importance of any one of these processes will vary depending on how water availability varies during the crop cycle. However, these three processes are not independent. Targeting specific traits to improve one process may have detrimental effects on the other two, but there may also be positive interactions. Progress in breeding for improved water-use efficiency of rain-fed wheat is reviewed to illustrate the nature of some of these interactions and to highlight opportunities that may be exploited in other crops as well as potential pitfalls. For C 3 species, measuring carbon isotope discrimination provides a powerful means of improving water-use efficiency of leaf gas exchange, but experience has shown that improvements in leaf-level wateruse efficiency may not always translate into higher crop water-use efficiency or yield. In fact, the reverse has frequently been observed. Reasons for this are explored in some detail. Crop simulation modelling can be used to assess the likely impact on water-use efficiency and yield of changing the expression of traits of interest. Results of such simulations indicate that greater progress may be achieved by pyramiding traits so that potential negative effects of individual traits are neutralized. DNA-based selection techniques may assist in such a strategy. Abbreviations: A, instantaneous rate of CO 2 assimilation; A/T, instantaneous water-use efficiency of leaf gas exchange; C a , atmospheric CO 2 concentration; C i , leaf internal CO 2 concentration; C i /C a , the ratio of internal and atmospheric CO 2 concentrations; D 13 C, carbon isotope discrimination; E, evaporation from the soil; ET, evapotranspiration, the sum of soil evaporation and plant transpiration from a crop canopy (instantaneous or cumulative); G, stomatal conductance; HI, harvest index; T, instantaneous rate of transpiration from a single leaf, and transpiration from a crop canopy (instantaneous or cumulative); T/ET, the ratio of transpiration to evapotranspiration; W, transpiration efficiency of crop biomass production; W a , atmospheric water vapour concentration; W i , leaf internal water vapour concentration.

Tel. 55 16 273 9341 FAX. 55 16 273 9372 ABSTRACT In this article we discuss artificial neural networks-based fault detection and isolation applications for robotic manipulators. The artificial neural networks (ANNs) are used for both residual generation and residual analysis. A multilayer perceptron (MLP) is employed to reproduce the dynamics of the robotic manipulator. Its outputs are compared with actual position and velocity measurements, generating the so-called residual vector. The residuals, when properly analyzed, provides an indication of the status of the robot (normal or faulty operation). Three ANNs architectures are employed in the residual analysis. The first is a radial basis function network (RBFN) which uses the residuals of position and velocity to perform fault identification. The second is again an RBFN, except that it uses only the velocity residuals.

This paper presents the design of a new and novel control technique applied to an active suspension system of a quarter car model using adaptive fuzzy (AF) logic and active force control (AFC) strategies. The two main advantages of the proposed method are the simplicity of the control law and low computational burden. The overall control system essentially comprises three feedback control loops, namely the innermost PI control loop for the force tracking of the hydraulic actuator, intermediate AFC control loops for the compensation of the disturbances and outermost AF control loop for the computation of the optimum target/commanded force. AF algorithms were used to approximate the estimated mass of the hydraulic actuator in the AFC loop. The performance of the proposed control method was then simulated, evaluated and later compared to examine the effectiveness of the system in suppressing the undesirable effects of the suspension system. It was found that the active suspension system with Adaptive Fuzzy Active Force Control (AF-AFC) yields superior performance compared to the AF system without AFC and the passive counterparts.

The study area is located in the northern Limpopo Province of South Africa. The aim of the study was to identify groundwater targets that could assist in improving the quality of life of rural communities. Airborne magnetic data was interpreted to identify dykes, lineaments and magnetic sources that could control groundwater occurrences. The length, parallelism of magnetic lineaments in some parts of the area suggests emplacement under tensional stress field along pre-existing zones of weakness. Lineaments extracted from the airborne magnetic data and satellite imagery data were superimposed on drainage lines to investigate the relative importance of structural features controlling the distribution of surface water and groundwater. In addition, normalized difference vegetation index (NDVI) was used in identifying areas of vegetation banding, which enable inference of fracture zones and high moisture content in the soil. The study shows that the northern and central eastern parts of the study area are more prospective for groundwater occurrence, while the southern and south-western parts of the project area are dry with no surface manifestation of groundwater. Integration of lineaments derived from aeromagnetic data and Landsat imagery as well with the NDVI was able to identify areas with a potential for groundwater occurrence at a regional scale.