Načrtovanje in planiranje z metodo simulacije

The use of simulation as a tool to design complex stochastic systems is often inhibited by cost. Extensive computer processing is needed to find a design parameter value given a desired target for the performance measure of a given system. The designer simulates the process numerically and obtains an approximation for that same output. The goal is to match the numerical and experimental results as closely as possible by varying the values of input parameters in the numerical simulation. The most obvious difficulty in solving the design problem is that one cannot simply calculate a straightforward solution and be done. Since the output has to be matched by varying the input, an iterative method of solution is implied. This paper proposes a “stochastic approximation” algorithm to estimate the necessary controllable input parameters within a desired accuracy given a target value for the performance function. The proposed solution algorithm is based on Newton’s methods using a single-run simulation approach to estimate the needed derivative. The proposed approach may be viewed as an optimization scheme, where a loss function must be minimized. The solution algorithm properties and the validity of the estimates are examined by applying it to some reliability and queueing systems with known analytical solutions.Uporaba simulacije kot orodja za načrtovanje kompleksnih stohastičnih sistemov je pogosto časovno zahtevna naloga. Potereben je izdaten računalniški čas da se najde vrednost vhodnih parametrov ki ustrezajo željenim performansam sistema. Načrtovalec simulira proces numerično za izbrane vhodne parametre da dobije oceno želene vrednosti izhoda. Cilj je da dobimo kar se da slične vrednosti experimentalnih in simulacijskih rezultatov z variranjem vhodnih parametrov simulacijskega modela. Pproblem je da ne obstaja enostaven način računanja da direkto dobimo zahtevanno rešitev problema. Ker izhod (rešitev) mora odgovarati enoj od možnih vrednosti vhodnih parametrov metoda reševanja je nujno iterativna kar zahteva veliko računalniškega časa. V tem članku predlagava postopek “stohastičnega približka” za oceno potrebnih controlabinih vhodnih parametrov za določitev željene vrednosti sistema v mejah predpisane zanesljivosti. Predlagani algoritam temelji na Newtonovi metodi, kjer spomočjo (enega) simulaciijskega teka ocenimo prvi odvod potreban za optimizacijo kriterijske funkcije. Predlagani postopek lahko razumemo kot optimizacijsko shemo, kjer funkcijo izgube je treba minimizirati. Predlagani postopek je preizkušen in ovrednoten na nekaj primerih zanesljivosti in sistemov strežbe z znanimi analitičnimi rešitvami

Comparative Analysis of System Dynamics and Object-Oriented Bayesian Networks Modelling for Water Systems Management

Copyright © 2012 Springer. The final publication is available at link.springer.comThis paper presents a comparative analysis of System Dynamics Modelling (SDM) and Object-Oriented Bayesian Networks (OOBN). Both techniques are extensively used for water resources modelling due to their flexibility, effectiveness in assessing different management options, ease of operation and suitability for encouraging stakeholder involvement. Conversely, both approaches have several important differences that make them complementary. For example, while SDM is more suitable for simulating the feedback dynamics of processes, OOBN modelling is a powerful tool for modelling systems with uncertain inputs (or outputs) characterised by probability distributions. This comparative analysis is applied to the Kairouan aquifer system, Tunisia, where the aquifer plays an essential role for socio-economic development in the region. Both models produced comparable results using baseline data, and show their complementarity through a suite of scenario tests. It is shown that reducing pumping of groundwater to coastal cities may prove the key to reducing the current aquifer deficit, though local demand reduction must be considered to preserve the agricultural economy. It is suggested that water management assessment should be tackled using both approaches to complement each other, adding depth and insight, and giving a more coherent picture of the problem being addressed, allowing for robust policy decisions to be made

College of Agricultural Sciences and Natural Resources: 23rd Annual Report August 1, 2015-July 31, 2016

Covers administration and staff, academic unit administrators, standing committees, ad hoc committees, departmental and academic program news and events, student leadership, student organizations, honors, Dean\u27s list, degrees conferred, graduate fellowships, scholarship report, alumni, Curriculum Committee actions, substitutions and waivers, online education, recruitment, retention, and placement, international engagement, teaching faculty, faculty awards and recognitions, faculty publications, grants funded, faculty appointments, undergraduate student enrollment, graduate student enrollment, and enrollment charts. The 2015-2016 Annual Report is dedicated to Ronnie and Jane Green

2000 - Geology Bibliography of California, 1854–2000

The scope of this database is much broader in scope than the original list of consultant reports submitted to Monterey County governmental agencies and includes extensive references on regional geologic mapping, hydrogeology, economic geology, and research done in connection with the Parkfield Earthquake Prediction Experiment. Major sources of information include: • Monterey County Planning Department: a database of approximately 2,000 references within the categories of geology, soil, water resources, and water quality. • Monterey County Water Resources Agency. • Monterey Peninsula Water Management District. • The American Geological Institute’s GeoRef database. • The U.S. Geological Survey’s National Geologic Map Database. • An online bibliography of research conducted in the northern Santa Lucia Mountains, Big Sur, and surrounding area published for the Santa Lucia Natural History Symposium (sponsored by Esalen Institute and University of California Big Creek Reserve, 1994–1997). • Library catalogs of the U.S. Geological Survey, University of California, California State University, Stanford University, and the California Institute of Technology. The list of nearly 4,300 references was prepared to further the County of Monterey\u27s 21st Century General Plan Update in order to have the most complete data available for planning and policy decisions.https://digitalcommons.csumb.edu/hornbeck_cgb_5/1037/thumbnail.jp

Network Analysis, Creative System Modelling and Decision Support: The NetSyMoD Approach

This paper presents the NetSyMoD approach – where NetSyMod stands for Network Analysis – Creative System Modelling – Decision Support. It represents the outcome of several years of research at FEEM in the field of natural resources management, environmental evaluation and decision-making, within the Natural Resources Management Research Programme. NetSyMoD is a flexible and comprehensive methodological framework, which uses a suite of support tools, aimed at facilitating the involvement of stakeholders or experts in decision-making processes. The main phases envisaged for the process are: (i) the identification of relevant actors, (ii) the analysis of social networks, (iii) the creative system modelling and modelling of the reality being considered (i.e. the local socio-economic and environmental system), and (iv) the analysis of alternative options available for the management of the specific case (e.g. alternative projects, plans, strategies). The strategies for participation are necessarily context-dependent, and thus not all the NetSyMod phases may be needed in every application. Furthermore, the practical solutions for their implementation may significantly differ from one case to another, depending not only on the context, but also on the available resources (human and financial). The various applications of NetSyMoD have nonetheless in common the same approach for problem analysis and communication within a group of actors, based upon the use of creative thinking techniques, the formalisation of human-environment relationships through the DPSIR framework, and the use of multi-criteria analysis through the mDSS software.Social Network, Integrated Analysis, Participatory Modelling, Decision Support

A novel planning approach for the water, sanitation and hygiene (WaSH) sector: the use of object-oriented bayesian networks

Conventional approaches to design and plan water, sanitation, and hygiene (WaSH) interventions are not suitable for capturing the increasing complexity of the context in which these services are delivered. Multidimensional tools are needed to unravel the links between access to basic services and the socio-economic drivers of poverty. This paper applies an object-oriented Bayesian network to reflect the main issues that determine access to WaSH services. A national Program in Kenya has been analyzed as initial case study. The main findings suggest that the proposed approach is able to accommodate local conditions and to represent an accurate reflection of the complexities of WaSH issues, incorporating the uncertainty intrinsic to service delivery processes. Results indicate those areas in which policy makers should prioritize efforts and resources. Similarly, the study shows the effects of sector interventions, as well as the foreseen impact of various scenarios related to the national Program.Preprin

A Mechanism Design Approach to Bandwidth Allocation in Tactical Data Networks

The defense sector is undergoing a phase of rapid technological advancement, in the pursuit of its goal of information superiority. This goal depends on a large network of complex interconnected systems - sensors, weapons, soldiers - linked through a maze of heterogeneous networks. The sheer scale and size of these networks prompt behaviors that go beyond conglomerations of systems or `system-of-systems\u27. The lack of a central locus and disjointed, competing interests among large clusters of systems makes this characteristic of an Ultra Large Scale (ULS) system. These traits of ULS systems challenge and undermine the fundamental assumptions of today\u27s software and system engineering approaches. In the absence of a centralized controller it is likely that system users may behave opportunistically to meet their local mission requirements, rather than the objectives of the system as a whole. In these settings, methods and tools based on economics and game theory (like Mechanism Design) are likely to play an important role in achieving globally optimal behavior, when the participants behave selfishly. Against this background, this thesis explores the potential of using computational mechanisms to govern the behavior of ultra-large-scale systems and achieve an optimal allocation of constrained computational resources Our research focusses on improving the quality and accuracy of the common operating picture through the efficient allocation of bandwidth in tactical data networks among self-interested actors, who may resort to strategic behavior dictated by self-interest. This research problem presents the kind of challenges we anticipate when we have to deal with ULS systems and, by addressing this problem, we hope to develop a methodology which will be applicable for ULS system of the future. We build upon the previous works which investigate the application of auction-based mechanism design to dynamic, performance-critical and resource-constrained systems of interest to the defense community. In this thesis, we consider a scenario where a number of military platforms have been tasked with the goal of detecting and tracking targets. The sensors onboard a military platform have a partial and inaccurate view of the operating picture and need to make use of data transmitted from neighboring sensors in order to improve the accuracy of their own measurements. The communication takes place over tactical data networks with scarce bandwidth. The problem is compounded by the possibility that the local goals of military platforms might not be aligned with the global system goal. Such a scenario might occur in multi-flag, multi-platform military exercises, where the military commanders of each platform are more concerned with the well-being of their own platform over others. Therefore there is a need to design a mechanism that efficiently allocates the flow of data within the network to ensure that the resulting global performance maximizes the information gain of the entire system, despite the self-interested actions of the individual actors. We propose a two-stage mechanism based on modified strictly-proper scoring rules, with unknown costs, whereby multiple sensor platforms can provide estimates of limited precisions and the center does not have to rely on knowledge of the actual outcome when calculating payments. In particular, our work emphasizes the importance of applying robust optimization techniques to deal with the uncertainty in the operating environment. We apply our robust optimization - based scoring rules algorithm to an agent-based model framework of the combat tactical data network, and analyze the results obtained. Through the work we hope to demonstrate how mechanism design, perched at the intersection of game theory and microeconomics, is aptly suited to address one set of challenges of the ULS system paradigm - challenges not amenable to traditional system engineering approaches

The effect of infrastructure changes on railway operations.

This paper makes use of standard simulation programs in combination with the tools of applied statistics to simulate railway operations. The purpose of the use of this tool is to evaluate and compare different possible kinds of railway infrastructure, like different types of signaling procedures, different network configuration or operational procedures. A railway system is a logistic network and because of the demand for improved railway operation, much work has been undertaken lately in this scientific field. However the author postulates the hypothesis based on a literature review that in a lot of these works there is a lack of full application of statistics. With this paper the author makes use of standard simulation programs for detailed simulation of railway operation especially with respect to the signaling and operation procedures. Additionally the influence of delays, which occur during real life railway operation is taken into account for a first time. This allows statistical evaluation of the results based on statistical significance. Also sensitivity analysis could be performed. It is demonstrated, that the results of such simulation runs show superior results when compared to other techniques not taking into account the variability. Additionally, procedures were developed to find the capacity of a railway network with the help of additional software tools. In this work the software package ARENA is used to simulate the operation of trains in railway networks. For this approach two major obstacles have to be solved: the simulation of train travelling times and the simulation of block rules used in railway operation. By introduction of visualization the confidence in the results of simulation, even for stakeholders not familiar with this technique, is increased. In this paper it is shown that with ARENA it is possible to calculate the capacity of different railway networks (scenarios). The results, which are calculated using quasi steady state simulation without variation, are similar to those obtained with other calculation methods. Additionally in one scenario the rule of thumb for the quotient between theoretical capacity and practical capacity in a railway network is confirmed by simulation including random variation. It is also demonstrated that OptQuest, an additional software package available for ARENA, is a suitable tool to find near optimal timetables in a scenario including delays. The results of this work may be not only of interest for railway operators, but also for operators of other automated transport systems. Such systems may be unmanned transport vehicles in a factory, transporting goods between different manufacturing stations. But also for automation of road traffic the results may be of interest