Remuneration of the reactive power in the Argentinean supply market; Remuneracao da potencia reativa no mercado de suprimento argentino

Energy Technology Data Exchange (ETDEWEB)

Kerszberg, Ernesto M; Dravnovsky, Mario Carlos [Administradora del Mercado Mayorista Eletrico S.A. (Argentina)

1996-05-01

This work presents the standards and legislation about power reactive consumption by involved agents in the market electric power supply. It discusses how to remunerate this reactive and the compromises among the actors of the power electric system

Offshore Supply Industry Dynamics

DEFF Research Database (Denmark)

Roslyng Olesen, Thomas

This report is part of the research project “The competitive challenges and strategic development possibilities for The Blue Denmark”, which was launched in 2014. The project is funded by the Danish Maritime Fund and carried out by researchers at CBS Maritime which is a Business in Society Platform...... with companies in the maritime sector. This report “Offshore Supply Industry Dynamics – Business strategies in the offshore supply industry” is the second report in mapping project D. It examines the markets and business strategies of various suppliers and furthermore presents an analysis of the challenges...... at Copenhagen Business School with a focus on value creation in the maritime industries. The project embraces various maritime segments from shipping and offshore to ports and suppliers. The research questions for the individual projects have been formulated by researchers at CBS Maritime in cooperation...

Estimation of dynamic reactivity using an H∞ optimal filter with a nonlinear term

International Nuclear Information System (INIS)

Suzuki, Katsuo; Watanabe, Koiti

1996-01-01

A method of nonlinear filtering is applied to the problem of estimating the dynamic reactivity of a nonlinear reactor system. The nonlinear filtering algorithm developed is a simple modification of a linear H ∞ optimal filter with a nonlinear feedback loop added. The linear filter is designed on the basis of a linearized dynamical system model that consists of linearized point reactor kinetic equations and a reactivity state equation driven by a fictitious signal. The latter is artificially introduced to deal with the reactivity as a state variable. The results of the computer simulation show that the nonlinear filtering algorithm can be applied to estimate the dynamic reactivity of the nonlinear reactor system, even under relatively large reactivity disturbances

National supply of reactivity control rods for Embalse nuclear power plant (CNE)

International Nuclear Information System (INIS)

Biondo, C.D.; Carloni, J.G.; Aba, J.A.

1987-01-01

The manufacture and supply on industrial scale of reactivity control rods for CNE (Embalse nuclear power plant) were developed by the National Atomic Energy Commission (CNEA) together with the private industry, as part of a program aimed to the substitution of imported supplies used in the operation of power plants by materials manufactured in Argentina. So far, the control rods were imported from Canada. In this work, the different development stages performed by CNEA and CONUAR S.A. are described, leading to the supply of a set of 21 cobalt rods to be included in a reactor of CNE in order to qualify this component. Among the main activities performed, the following stand out: specifications development, particularly those concerning to cobalt cores, evaluation of design documentation and elaboration of bidding conditions and a plan of manufacture and control. According to the results obtained during the service and the post-irradiation measurements, the design will be reviewed in order to undertake new manufacturing plans. (Author)

Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns

International Nuclear Information System (INIS)

Wishart, J.F.

2011-01-01

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs generally have low volatilities and are combustion-resistant, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of primary radiation chemistry, charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of reactions and product distributions. We study these issues by characterization of primary radiolysis products and measurements of their yields and reactivity, quantification of electron solvation dynamics and scavenging of electrons in different states of solvation. From this knowledge we wish to learn how to predict radiolytic mechanisms and control them or mitigate their effects on the properties of materials used in nuclear fuel processing, for example, and to apply IL radiation chemistry to answer questions about general chemical reactivity in ionic liquids that will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that the slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increase the importance of pre-solvated electron reactivity and consequently alter product distributions and subsequent chemistry. This difference from conventional solvents has profound effects on predicting and controlling radiolytic yields

Population Model with a Dynamic Food Supply

Science.gov (United States)

Dickman, Ronald; da Silva Nascimento, Jonas

2009-09-01

We propose a simple population model including the food supply as a dynamic variable. In the model, survival of an organism depends on a certain minimum rate of food consumption; a higher rate of consumption is required for reproduction. We investigate the stationary behavior under steady food input, and the transient behavior of growth and decay when food is present initially but is not replenished. Under a periodic food supply, the system exhibits period-doubling bifurcations and chaos in certain ranges of the reproduction rate. Bifurcations and chaos are favored by a slow reproduction rate and a long period of food-supply oscillation.

Reactivating dynamics for the susceptible-infected-susceptible model: a simple method to simulate the absorbing phase

Science.gov (United States)

Macedo-Filho, A.; Alves, G. A.; Costa Filho, R. N.; Alves, T. F. A.

2018-04-01

We investigated the susceptible-infected-susceptible model on a square lattice in the presence of a conjugated field based on recently proposed reactivating dynamics. Reactivating dynamics consists of reactivating the infection by adding one infected site, chosen randomly when the infection dies out, avoiding the dynamics being trapped in the absorbing state. We show that the reactivating dynamics can be interpreted as the usual dynamics performed in the presence of an effective conjugated field, named the reactivating field. The reactivating field scales as the inverse of the lattice number of vertices n, which vanishes at the thermodynamic limit and does not affect any scaling properties including ones related to the conjugated field.

Structural network heterogeneities and network dynamics: a possible dynamical mechanism for hippocampal memory reactivation.

Science.gov (United States)

Jablonski, Piotr; Poe, Gina; Zochowski, Michal

2007-03-01

The hippocampus has the capacity for reactivating recently acquired memories and it is hypothesized that one of the functions of sleep reactivation is the facilitation of consolidation of novel memory traces. The dynamic and network processes underlying such a reactivation remain, however, unknown. We show that such a reactivation characterized by local, self-sustained activity of a network region may be an inherent property of the recurrent excitatory-inhibitory network with a heterogeneous structure. The entry into the reactivation phase is mediated through a physiologically feasible regulation of global excitability and external input sources, while the reactivated component of the network is formed through induced network heterogeneities during learning. We show that structural changes needed for robust reactivation of a given network region are well within known physiological parameters.

The scattering matrix element of the three body reactive collision

International Nuclear Information System (INIS)

Morsy, M.W.; Hilal, A.A.; El-Sabagh, M.A.

1980-08-01

The optical model approximation has been applied to a previously derived set of coupled equations representing the dynamics of the three-body reactive scattering. The Schroedinger equation obtained describing the scattering problem has then been solved by inserting the effective mass approximation. The asymptotic requirements for both the entrance and exit channels, respectively, have been supplied to give the scattering matrix element of the reactive collision. (author)

Modeling the dynamics of Plasmodium vivax infection and hypnozoite reactivation in vivo.

Directory of Open Access Journals (Sweden)

Adeshina I Adekunle

2015-03-01

Full Text Available The dynamics of Plasmodium vivax infection is characterized by reactivation of hypnozoites at varying time intervals. The relative contribution of new P. vivax infection and reactivation of dormant liver stage hypnozoites to initiation of blood stage infection is unclear. In this study, we investigate the contribution of new inoculations of P. vivax sporozoites to primary infection versus reactivation of hypnozoites by modeling the dynamics of P. vivax infection in Thailand in patients receiving treatment for either blood stage infection alone (chloroquine, or the blood and liver stages of infection (chloroquine + primaquine. In addition, we also analysed rates of infection in a study in Papua New Guinea (PNG where patients were treated with either artesunate, or artesunate + primaquine. Our results show that up to 96% of the P. vivax infection is due to hypnozoite reactivation in individuals living in endemic areas in Thailand. Similar analysis revealed the around 70% of infections in the PNG cohort were due to hypnozoite reactivation. We show how the age of the cohort, primaquine drug failure, and seasonality may affect estimates of the ratio of primary P. vivax infection to hypnozoite reactivation. Modeling of P. vivax primary infection and hypnozoite reactivation provides important insights into infection dynamics, and suggests that 90-96% of blood stage infections arise from hypnozoite reactivation. Major differences in infection kinetics between Thailand and PNG suggest the likelihood of drug failure in PNG.

Dynamics of Reactive Microbial Hotspots in Concentration Gradient.

Science.gov (United States)

Hubert, A.; Farasin, J.; Tabuteau, H.; Dufresne, A.; Meheust, Y.; Le Borgne, T.

2017-12-01

In subsurface environments, bacteria play a major role in controlling the kinetics of a broad range of biogeochemical reactions. In such environments, nutrients fluxes and solute concentrations needed for bacteria metabolism may be highly variable in space and intermittent in time. This can lead to the formation of reactive hotspots where and when conditions are favorable to particular microorganisms, hence inducing biogeochemical reaction kinetics that differ significantly from those measured in homogeneous model environments. To investigate the impact of chemical gradients on the spatial structure and temporal dynamics of subsurface microorganism populations, we develop microfluidic cells allowing for a precise control of flow and chemical gradient conditions, as well as quantitative monitoring of the bacteria's spatial distribution and biofilm development. Using the non-motile Escherichia coli JW1908-1 strain and Gallionella capsiferriformans ES-2 as model organisms, we investigate the behavior and development of bacteria over a range of single and double concentration gradients in the concentrations of nutrients, electron donors and electron acceptors. We measure bacterial activity and population growth locally in precisely known hydrodynamic and chemical environments. This approach allows time-resolved monitoring of the location and intensity of reactive hotspots in micromodels as a function of the flow and chemical gradient conditions. We compare reactive microbial hotspot dynamics in our micromodels to classic growth laws and well-known growth parameters for the laboratory model bacteria Escherichia coli.We also discuss consequences for the formation and temporal dynamics of biofilms in the subsurface.

A Dynamic Stackelberg Game of Supply Chain for a Corporate Social Responsibility

Directory of Open Access Journals (Sweden)

Massimiliano Ferrara

2017-01-01

Full Text Available In this paper, we establish a dynamic game to allocate CSR (Corporate Social Responsibility to the members of a supply chain. We propose a model of a supply chain in a decentralized state which includes a supplier and a manufacturer. For analyzing supply chain performance in decentralized state and the relationships between the members of the supply chain, we formulate a model that crosses through multiperiods with the help of a dynamic discrete Stackelberg game which is made under two different information structures. We obtain an equilibrium point at which both the profits of members and the level of CSR taken up by supply chains are maximized.

Transparency in complex dynamic food supply chains

NARCIS (Netherlands)

Trienekens, J.H.; Wognum, P.M.; Beulens, A.J.M.; Vorst, van der J.G.A.J.

2012-01-01

Food supply chains are increasingly complex and dynamic due to (i) increasing product proliferation to serve ever diversifying and globalising markets as a form of mass customisation with resulting global flows of raw materials, ingredients and products, and (ii) the need to satisfy changing and

The Dynamics of network and dyad level supply management

DEFF Research Database (Denmark)

Ellegaard, Chris

-supplier relation and its immediate network context, are presented. In analysing the data, the dynamic interdependency between management of one level and management of the other, will be demonstrated. The analysis reveals a need for an alternating approach to supply management, which takes the dynamic complexity...

Efficient Kinect Sensor-Based Reactive Path Planning Method for Autonomous Mobile Robots in Dynamic Environments

Energy Technology Data Exchange (ETDEWEB)

Tuvshinjargal, Doopalam; Lee, Deok Jin [Kunsan National University, Gunsan (Korea, Republic of)

2015-06-15

In this paper, an efficient dynamic reactive motion planning method for an autonomous vehicle in a dynamic environment is proposed. The purpose of the proposed method is to improve the robustness of autonomous robot motion planning capabilities within dynamic, uncertain environments by integrating a virtual plane-based reactive motion planning technique with a sensor fusion-based obstacle detection approach. The dynamic reactive motion planning method assumes a local observer in the virtual plane, which allows the effective transformation of complex dynamic planning problems into simple stationary ones proving the speed and orientation information between the robot and obstacles. In addition, the sensor fusion-based obstacle detection technique allows the pose estimation of moving obstacles using a Kinect sensor and sonar sensors, thus improving the accuracy and robustness of the reactive motion planning approach. The performance of the proposed method was demonstrated through not only simulation studies but also field experiments using multiple moving obstacles in hostile dynamic environments.

Efficient Kinect Sensor-Based Reactive Path Planning Method for Autonomous Mobile Robots in Dynamic Environments

International Nuclear Information System (INIS)

Tuvshinjargal, Doopalam; Lee, Deok Jin

2015-01-01

In this paper, an efficient dynamic reactive motion planning method for an autonomous vehicle in a dynamic environment is proposed. The purpose of the proposed method is to improve the robustness of autonomous robot motion planning capabilities within dynamic, uncertain environments by integrating a virtual plane-based reactive motion planning technique with a sensor fusion-based obstacle detection approach. The dynamic reactive motion planning method assumes a local observer in the virtual plane, which allows the effective transformation of complex dynamic planning problems into simple stationary ones proving the speed and orientation information between the robot and obstacles. In addition, the sensor fusion-based obstacle detection technique allows the pose estimation of moving obstacles using a Kinect sensor and sonar sensors, thus improving the accuracy and robustness of the reactive motion planning approach. The performance of the proposed method was demonstrated through not only simulation studies but also field experiments using multiple moving obstacles in hostile dynamic environments

Real-Time Reactive Power Distribution in Microgrids by Dynamic Programing

DEFF Research Database (Denmark)

Levron, Yoash; Beck, Yuval; Katzir, Liran

2017-01-01

In this paper a new real-time optimization method for reactive power distribution in microgrids is proposed. The method enables location of a globally optimal distribution of reactive power under normal operating conditions. The method exploits the typical compact structure of microgrids to obtain...... combination of reactive powers, by means of dynamic programming. Since every single step involves a one-dimensional problem, the complexity of the solution is only linear with the number of clusters, and as a result, a globally optimal solution may be obtained in real time. The paper includes the results...

Dynamic Impact of Online Word-of-Mouth and Advertising on Supply Chain Performance.

Science.gov (United States)

Feng, Jian; Liu, Bin

2018-01-04

Cooperative (co-op) advertising investments benefit brand goodwill and further improve supply chain performance. Meanwhile, online word-of-mouth (OWOM) can also play an important role in supply chain performance. On the basis of co-op advertising, this paper considers a single supply chain structure led by a manufacturer and examines a fundamental issue concerning the impact of OWOM on supply chain performance. Firstly, by the method of differential game, this paper analyzes the dynamic impact of OWOM and advertising on supply chain performance (i.e., brand goodwill, sales, and profits) under three different supply chain decisions (i.e., only advertising, and manufacturers with and without sharing cost of OWOM with retailers). We compare and analyze the optimal strategies of advertising and OWOM under the above different supply chain decisions. Secondly, the system dynamics model is established to reflect the dynamic impact of OWOM and advertising on supply chain performance. Finally, three supply chain decisions under two scenarios, strong brand and weak brand, are analyzed through the system dynamics simulation. The results show that the input of OWOM can enhance brand goodwill and improve earnings. It further promotes the OWOM reputation and improves the supply chain performance if manufacturers share the cost of OWOM with retailers. Then, in order to eliminate the retailers from word-of-mouth fraud and establish a fair competition mechanism, the third parties (i.e., regulators or e-commerce platforms) should take appropriate punitive measures against retailers. Furthermore, the effect of OWOM on supply chain performance under a strong brand differed from those under a weak brand. Last but not least, if OWOM is improved, there would be more remarkable performance for the weak brand than that for the strong brand in the supply chain.

Dynamic Impact of Online Word-of-Mouth and Advertising on Supply Chain Performance

Science.gov (United States)

Feng, Jian

2018-01-01

Cooperative (co-op) advertising investments benefit brand goodwill and further improve supply chain performance. Meanwhile, online word-of-mouth (OWOM) can also play an important role in supply chain performance. On the basis of co-op advertising, this paper considers a single supply chain structure led by a manufacturer and examines a fundamental issue concerning the impact of OWOM on supply chain performance. Firstly, by the method of differential game, this paper analyzes the dynamic impact of OWOM and advertising on supply chain performance (i.e., brand goodwill, sales, and profits) under three different supply chain decisions (i.e., only advertising, and manufacturers with and without sharing cost of OWOM with retailers). We compare and analyze the optimal strategies of advertising and OWOM under the above different supply chain decisions. Secondly, the system dynamics model is established to reflect the dynamic impact of OWOM and advertising on supply chain performance. Finally, three supply chain decisions under two scenarios, strong brand and weak brand, are analyzed through the system dynamics simulation. The results show that the input of OWOM can enhance brand goodwill and improve earnings. It further promotes the OWOM reputation and improves the supply chain performance if manufacturers share the cost of OWOM with retailers. Then, in order to eliminate the retailers from word-of-mouth fraud and establish a fair competition mechanism, the third parties (i.e., regulators or e-commerce platforms) should take appropriate punitive measures against retailers. Furthermore, the effect of OWOM on supply chain performance under a strong brand differed from those under a weak brand. Last but not least, if OWOM is improved, there would be more remarkable performance for the weak brand than that for the strong brand in the supply chain. PMID:29300361

Reactive power management and voltage control in deregulated power markets

Science.gov (United States)

Spangler, Robert G.

The research that is the subject of this dissertation is about the management of reactive power and voltage support in the wholesale open access power markets in the United States (US). The purpose of this research is to place decisions about open access market structures, as they relate to reactive power and voltage control, on a logical and consistent economic basis, given the engineering needs of a commercial electric power system. An examination of the electricity markets operating in the US today reveals that current approaches to reactive power management and voltage support are extensions of those based on historical, regulated monopoly electric service. A case for change is built by first looking at the subject of reactive power from an engineering viewpoint and then from an economic perspective. Ultimately, a set of market rules for managing reactive power and voltage support is proposed. The proposal suggests that cost recovery for static and dynamic VARs is appropriately accomplished through the regulated transmission cost of service. Static VAR cost recovery should follow traditional rate recovery methodologies. In the case of dynamic VARs, this work provides a methodology based on the microeconomic theory of the firm for determining such cost. It further suggests that an operational strategy that reduces and limits the use of dynamic VARs, during normal operations, is appropriate. This latter point leads to an increase in the fixed cost of the transmission network but prevents price spikes and short supply situations from affecting, or being affected by, the reactive capability limitations associated with dynamic VARs supplied from synchronous generators. The rules are consistent with a market structure that includes competitive generation and their application will result in the communication of a clear understanding of the responsibilities, related to voltage control, of each type of market entity. In this sense, their application will contribute to

Long-Term Groundwater Monitoring Optimization, Clare Water Supply Superfund Site, Permeable Reactive Barrier and Soil Remedy Areas, Clare, Michigan

Science.gov (United States)

This report contains a review of the long-term groundwater monitoring network for the Permeable Reactive Barrier (PRB) and Soil Remedy Areas at the Clare Water Supply Superfund Site in Clare, Michigan.

Operational experience with reactive power control methods optimized for tokamak power supplies

International Nuclear Information System (INIS)

Sihler, C.; Huart, M.; Kaesemann, C.-P.; Streibl, B.

2003-01-01

The power and energy of the ASDEX Upgrade (AUG) tokamak are provided by two separate 10.5 kV, 110-85 Hz networks based on the flywheel generators EZ3-EZ4 in addition to the generator EZ2 dedicated to the toroidal field coil. The 10.5 kV networks supply the thyristor converters allowing fast control of the DC currents in the AUG poloidal field coils. Two methods for improving the load power factor in the present experimental campaign of AUG have been investigated, namely the control of the phase-to-neutral voltage in thyristor converters fitted with neutral thyristors, such as the new 145 MVA modular thyristor converter system (Group 6), and reactive power control achieved by means of static VAr compensators (SVC). The paper shows that reliable compensation up to 90 MVAr was regularly achieved and that electrical transients in SVC modules can be kept at an acceptable level. The paper will discuss the results from the reactive power reduction by SVC and neutral thyristor control and draw a comparative conclusion

Approximate photochemical dynamics of azobenzene with reactive force fields

Science.gov (United States)

Li, Yan; Hartke, Bernd

2013-12-01

We have fitted reactive force fields of the ReaxFF type to the ground and first excited electronic states of azobenzene, using global parameter optimization by genetic algorithms. Upon coupling with a simple energy-gap transition probability model, this setup allows for completely force-field-based simulations of photochemical cis→trans- and trans→cis-isomerizations of azobenzene, with qualitatively acceptable quantum yields. This paves the way towards large-scale dynamics simulations of molecular machines, including bond breaking and formation (via the reactive force field) as well as photochemical engines (presented in this work).

Dynamic Supply Chain Design and Operations Plan for Connected Smart Factories with Additive Manufacturing

Directory of Open Access Journals (Sweden)

Byung Do Chung

2018-04-01

Full Text Available Interest in smart factories and smart supply chains has been increasing, and researchers have emphasized the importance and the effects of advanced technologies such as 3D printers, the Internet of Things, and cloud services. This paper considers an innovation in dynamic supply-chain design and operations: connected smart factories that share interchangeable processes through a cloud-based system for personalized production. In the system, customers are able to upload a product design file, an optimal supply chain design and operations plan are then determined based on the available resources in the network of smart factories. The concept of smart supply chains is discussed and six types of flexibilities are identified, namely: design flexibility, product flexibility, process flexibility, supply chain flexibility, collaboration flexibility, and strategic flexibility. Focusing on supply chain flexibility, a general planning framework and various optimization models for dynamic supply chain design and operations plan are proposed. Further, numerical experiments are conducted to analyze fixed, production, and transportation costs for various scenarios. The results demonstrate the extent of the dynamic supply chain design and operations problem, and the large variation in transportation cost.

The Configuration Of Supply Chain Agritourism To Improve The Performance With Dynamic Programming

Directory of Open Access Journals (Sweden)

Sahnaz Ubud

2015-09-01

Full Text Available The purposes of this research is to implementation about  the configuration of Supply Chain Agritourism in Mekarsari Tours Garden and result a decision making  which must be done by top level management about their supply chain configuration. Because now Mekarsari, the biggest fruit garden in the world, have a lot of type of fruit which must be supply for the customer depend on the season with on time. So Mekarsari must know about their configuration from supplier to customer to improve their performance. The Respondents  for this research is selected based on the results of supply chain maping from the worker in the garden, the top level management until the end customer. Supply chian network is formed consisting of farm workers to the end customers, especially those located in the tourist are of green land zone.  The type of data is displayed in a supply chain modeling approach is to use the dynamic system. It’s consists of numeric data, the written data and mental models.  That data is collected and processed into a design model. The design model is using system dynamics methodology. In compiling the system dynamics model has been used software Vensim Professional Academic Ventana 5.7. The result of this research is a configuration of Supply Chain Agritourism which is developed from the supplier until the end customer in Mekarsari tours Garden. From the Dynamic Programming, the result is a decision making which must be done by the top level management to improve the supply chain performance, especially in the green land zone.

Dynamics of confined reactive water in smectite clay-zeolite composites.

Science.gov (United States)

Pitman, Michael C; van Duin, Adri C T

2012-02-15

The dynamics of water confined to mesoporous regions in minerals such as swelling clays and zeolites is fundamental to a wide range of resource management issues impacting many processes on a global scale, including radioactive waste containment, desalination, and enhanced oil recovery. Large-scale atomic models of freely diffusing multilayer smectite particles at low hydration confined in a silicalite cage are used to investigate water dynamics in the composite environment with the ReaxFF reactive force field over a temperature range of 300-647 K. The reactive capability of the force field enabled a range of relevant surface chemistry to emerge, including acid/base equilibria in the interlayer calcium hydrates and silanol formation on the edges of the clay and inner surface of the zeolite housing. After annealing, the resulting clay models exhibit both mono- and bilayer hydration structures. Clay surface hydration redistributed markedly and yielded to silicalite water loading. We find that the absolute rates and temperature dependence of water dynamics compare well to neutron scattering data and pulse field gradient measures from relevant samples of Ca-montmorillonite and silicalite, respectively. Within an atomistic, reactive context, our results distinguish water dynamics in the interlayer Ca(OH)(2)·nH(2)O environment from water flowing over the clay surface, and from water diffusing within silicalite. We find that the diffusion of water when complexed to Ca hydrates is considerably slower than freely diffusing water over the clay surface, and the reduced mobility is well described by a difference in the Arrhenius pre-exponential factor rather than a change in activation energy.

Efficiency Enhancement of an Envelope Tracking Power Amplifier Combining Supply Shaping and Dynamic Biasing

DEFF Research Database (Denmark)

Tafuri, Felice Francesco; Sira, Daniel; Jensen, Ole Kiel

2013-01-01

This paper presents a new method to improve the performance of envelope tracking (ET) power amplifiers (PAs). The method consists of combining the supply modulation that characterizes the envelope tracking architecture with supply shaping and dynamic biasing. The inclusion of dynamic biasing allo...

Design of Simulink module for dynamic reactivity simulation of marine reactor automatic control rod

International Nuclear Information System (INIS)

Chen Zhiyun; Luo Lei; Chen Wenzhen; Gui Xuewen

2010-01-01

The power of marine reactor varies frequently and acutely, which induces the frequent and acute adjustment of the automatic control rod. According to the characteristics of marine reactor and the problem of improper control rod reactivity insertion in previous literatures, the Simulink module for dynamic reactivity simulation of automatic control rod was designed and adopted as a sub-module of Simulink program for the fast calculation of the physical and thermal parameters of marine reactor. A typical dynamic process of the marine reactor was used as the benchmark, which indicates that the designed Simulink module is capable of the dynamic simulation of automatic control rod position and reactivity, and is adequate to the fast calculation of physic and thermal parameters. The Simulink module is of significant meaning to the simulation of the dynamic process of marine reactor and the fast calculation of the operating parameters. (authors)

Markov switching of the electricity supply curve and power prices dynamics

Science.gov (United States)

Mari, Carlo; Cananà, Lucianna

2012-02-01

Regime-switching models seem to well capture the main features of power prices behavior in deregulated markets. In a recent paper, we have proposed an equilibrium methodology to derive electricity prices dynamics from the interplay between supply and demand in a stochastic environment. In particular, assuming that the supply function is described by a power law where the exponent is a two-state strictly positive Markov process, we derived a regime switching dynamics of power prices in which regime switches are induced by transitions between Markov states. In this paper, we provide a dynamical model to describe the random behavior of power prices where the only non-Brownian component of the motion is endogenously introduced by Markov transitions in the exponent of the electricity supply curve. In this context, the stochastic process driving the switching mechanism becomes observable, and we will show that the non-Brownian component of the dynamics induced by transitions from Markov states is responsible for jumps and spikes of very high magnitude. The empirical analysis performed on three Australian markets confirms that the proposed approach seems quite flexible and capable of incorporating the main features of power prices time-series, thus reproducing the first four moments of log-returns empirical distributions in a satisfactory way.

Analysis on the influence of supply method on a workstation with the help of dynamic simulation

Directory of Open Access Journals (Sweden)

Gavriluță Alin

2017-01-01

Full Text Available Considering the need of flexibility in any manufacturing process, the choice of the supply method of an assembly workstation can be a decision with instead influence on its performances. Using dynamic simulation, this article wants to compare the effect on a workstation cycle time of three different supply methods: supply on stock, supply in “Strike Zone” and synchronous supply. This study is part of an extended work that has the aim of compering by 3D layout design and dynamic simulation, different supply methods on an assembly line performances.

Supply risk analysis: applying system dynamics to the Colombian healthcare sector

Directory of Open Access Journals (Sweden)

Juan Pablo Zamora Aguas

2013-09-01

Full Text Available This paper addresses supply risk in the oncological medicine supply chain (SC in Colombia. A system dynamics model was developed for assessing supply risk impact on SC operation and performance. The costs of risk and logis-tics operation were evaluated in current conditions and in a risk mitigation scenario. The model was based on a systematic analysis of supply networks, mainly concerning the reduction of overall SC costs and improving service, quality and opportunity performance index. This article has resulted from research into SC risk management (SCRM carried out by the Universidad Nacional de Colombia’s SEPRO research group.

Study of IPR-R1 dynamics by reactivity random excitations

International Nuclear Information System (INIS)

Roedel, G.

1983-01-01

To demonstrate the viability of the utilization of analitical techniques of neutronic noise, a dynamic model for IPR-R1 reactor from CDTN was developed. This model allows reactivity feedback due to variations of temperature in fuel and coolant [pt

The rediscovery of industrial dynamics: the contribution of system dynamics to supply chain management in a dynamic and fragmented world

NARCIS (Netherlands)

Akkermans, H.A.; Dellaert, N.P.

2005-01-01

The field of supply chain management (SCM) almost started with the publication of Forrester's Industrial Dynamics, but it seems that the relevance of this seminal publication for the field of system dynamics has never been so relevant for the field of SCM than today. In this introduction to the

Supercomputer algorithms for reactivity, dynamics and kinetics of small molecules

International Nuclear Information System (INIS)

Lagana, A.

1989-01-01

Even for small systems, the accurate characterization of reactive processes is so demanding of computer resources as to suggest the use of supercomputers having vector and parallel facilities. The full advantages of vector and parallel architectures can sometimes be obtained by simply modifying existing programs, vectorizing the manipulation of vectors and matrices, and requiring the parallel execution of independent tasks. More often, however, a significant time saving can be obtained only when the computer code undergoes a deeper restructuring, requiring a change in the computational strategy or, more radically, the adoption of a different theoretical treatment. This book discusses supercomputer strategies based upon act and approximate methods aimed at calculating the electronic structure and the reactive properties of small systems. The book shows how, in recent years, intense design activity has led to the ability to calculate accurate electronic structures for reactive systems, exact and high-level approximations to three-dimensional reactive dynamics, and to efficient directive and declaratory software for the modelling of complex systems

Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns

International Nuclear Information System (INIS)

Wishart, J.F.

2008-01-01

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate

IONIC LIQUIDS: RADIATION CHEMISTRY, SOLVATION DYNAMICS AND REACTIVITY PATTERNS

International Nuclear Information System (INIS)

WISHART, J.F.

2007-01-01

energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate the influence of ILs on charge transport processes. Methods. Picosecond pulse radiolysis studies at BNL

Reactive-brittle dynamics in peridotite alteration

Science.gov (United States)

Evans, O.; Spiegelman, M. W.; Kelemen, P. B.

2017-12-01

The interactions between reactive fluids and brittle solids are critical in Earth dynamics. Implications of such processes are wide-ranging: from earthquake physics to geologic carbon sequestration and the cycling of fluids and volatiles through subduction zones. Peridotite alteration is a common feature in many of these processes, which - despite its obvious importance - is relatively poorly understood from a geodynamical perspective. In particular, alteration reactions are thought to be self-limiting in nature, contradicting observations of rocks that have undergone 100% hydration/carbonation. One potential explanation of this observation is the mechanism of "reaction-driven cracking": that volume changes associated with these reactions are large enough to fracture the surrounding rock, leading to a positive feedback where new reactive surfaces are exposed and fluid pathways are created. The purpose of this study is to investigate the relative roles of reaction, elastic stresses and surface tension in alteration reactions. In this regard we derive a system of equations describing reactive fluid flow in an elastically deformable porous media, and explore them via a combination of analytic and numerical solutions. Using this model we show that the final stress state of a dry peridotite that has undergone reaction depends strongly on the rates of reaction versus fluid transport: significant fluid flow driven by pressure and/or surface tension gradients implies higher fractions of serpentinization, leaving behind a highly stressed residuum of partially reacted material. Using a model set-up that mimics a cylindrical triaxial apparatus we predict that the resulting stresses would lead to tensile failure and the generation of radially oriented cracks.

Applying a Dynamic Resource Supply Model in a Smart Grid

Directory of Open Access Journals (Sweden)

Kaiyu Wan

2014-09-01

Full Text Available Dynamic resource supply is a complex issue to resolve in a cyber-physical system (CPS. In our previous work, a resource model called the dynamic resource supply model (DRSM has been proposed to handle resources specification, management and allocation in CPS. In this paper, we are integrating the DRSM with service-oriented architecture and applying it to a smart grid (SG, one of the most complex CPS examples. We give the detailed design of the SG for electricity charging request and electricity allocation between plug-in hybrid electric vehicles (PHEV and DRSM through the Android system. In the design, we explain a mechanism for electricity consumption with data collection and re-allocation through ZigBee network. In this design, we verify the correctness of this resource model for expected electricity allocation.

Characterising Wildlife Trade Market Supply-Demand Dynamics

Science.gov (United States)

Rowcliffe, M.; Cowlishaw, G.; Alexander, J. S.; Ntiamoa-Baidu, Y.; Brenya, A.; Milner-Gulland, E. J.

2016-01-01

The trade in wildlife products can represent an important source of income for poor people, but also threaten wildlife locally, regionally and internationally. Bushmeat provides livelihoods for hunters, traders and sellers, protein to rural and urban consumers, and has depleted the populations of many tropical forest species. Management interventions can be targeted towards the consumers or suppliers of wildlife products. There has been a general assumption in the bushmeat literature that the urban trade is driven by consumer demand with hunters simply fulfilling this demand. Using the urban bushmeat trade in the city of Kumasi, Ghana, as a case study, we use a range of datasets to explore the processes driving the urban bushmeat trade. We characterise the nature of supply and demand by explicitly considering three market attributes: resource condition, hunter behaviour, and consumer behaviour. Our results suggest that bushmeat resources around Kumasi are becoming increasingly depleted and are unable to meet demand, that hunters move in and out of the trade independently of price signals generated by the market, and that, for the Kumasi bushmeat system, consumption levels are driven not by consumer choice but by shortfalls in supply and consequent price responses. Together, these results indicate that supply-side processes dominate the urban bushmeat trade in Kumasi. This suggests that future management interventions should focus on changing hunter behaviour, although complementary interventions targeting consumer demand are also likely to be necessary in the long term. Our approach represents a structured and repeatable method to assessing market dynamics in information-poor systems. The findings serve as a caution against assuming that wildlife markets are demand driven, and highlight the value of characterising market dynamics to inform appropriate management. PMID:27632169

Space dependence of reactivity parameters on reactor dynamic perturbation measurements

International Nuclear Information System (INIS)

Maletti, R.; Ziegenbein, D.

1985-01-01

Practical application of reactor-dynamic perturbation measurements for on-power determination of differential reactivity weight of control rods and power coefficients of reactivity has shown a significant dependence of parameters on the position of outcore detectors. The space dependence of neutron flux signal in the core of a VVER-440-type reactor was measured by means of 60 self-powered neutron detectors. The greatest neutron flux alterations are located close to moved control rods and in height of the perturbation position. By means of computations, detector positions can be found in the core in which the one-point model is almost valid. (author)

Dynamics of global supply chain and electric power networks: Models, pricing analysis, and computations

Science.gov (United States)

Matsypura, Dmytro

In this dissertation, I develop a new theoretical framework for the modeling, pricing analysis, and computation of solutions to electric power supply chains with power generators, suppliers, transmission service providers, and the inclusion of consumer demands. In particular, I advocate the application of finite-dimensional variational inequality theory, projected dynamical systems theory, game theory, network theory, and other tools that have been recently proposed for the modeling and analysis of supply chain networks (cf. Nagurney (2006)) to electric power markets. This dissertation contributes to the extant literature on the modeling, analysis, and solution of supply chain networks, including global supply chains, in general, and electric power supply chains, in particular, in the following ways. It develops a theoretical framework for modeling, pricing analysis, and computation of electric power flows/transactions in electric power systems using the rationale for supply chain analysis. The models developed include both static and dynamic ones. The dissertation also adds a new dimension to the methodology of the theory of projected dynamical systems by proving that, irrespective of the speeds of adjustment, the equilibrium of the system remains the same. Finally, I include alternative fuel suppliers, along with their behavior into the supply chain modeling and analysis framework. This dissertation has strong practical implications. In an era in which technology and globalization, coupled with increasing risk and uncertainty, complicate electricity demand and supply within and between nations, the successful management of electric power systems and pricing become increasingly pressing topics with relevance not only for economic prosperity but also national security. This dissertation addresses such related topics by providing models, pricing tools, and algorithms for decentralized electric power supply chains. This dissertation is based heavily on the following

Performance metric optimization advocates CPFR in supply chains: A system dynamics model based study

OpenAIRE

Balaji Janamanchi; James R. Burns

2016-01-01

Background: Supply Chain partners often find themselves in rather helpless positions, unable to improve their firm’s performance and profitability because their partners although willing to share production information do not fully collaborate in tackling customer order variations as they don’t seem to appreciate the benefits of such collaboration. Methods: We use a two-player (supplier-manufacturer) System Dynamics model to study the dynamics to assess the impact and usefulness of supply cha...

Dynamic Heat Supply Prediction Using Support Vector Regression Optimized by Particle Swarm Optimization Algorithm

Directory of Open Access Journals (Sweden)

Meiping Wang

2016-01-01

Full Text Available We developed an effective intelligent model to predict the dynamic heat supply of heat source. A hybrid forecasting method was proposed based on support vector regression (SVR model-optimized particle swarm optimization (PSO algorithms. Due to the interaction of meteorological conditions and the heating parameters of heating system, it is extremely difficult to forecast dynamic heat supply. Firstly, the correlations among heat supply and related influencing factors in the heating system were analyzed through the correlation analysis of statistical theory. Then, the SVR model was employed to forecast dynamic heat supply. In the model, the input variables were selected based on the correlation analysis and three crucial parameters, including the penalties factor, gamma of the kernel RBF, and insensitive loss function, were optimized by PSO algorithms. The optimized SVR model was compared with the basic SVR, optimized genetic algorithm-SVR (GA-SVR, and artificial neural network (ANN through six groups of experiment data from two heat sources. The results of the correlation coefficient analysis revealed the relationship between the influencing factors and the forecasted heat supply and determined the input variables. The performance of the PSO-SVR model is superior to those of the other three models. The PSO-SVR method is statistically robust and can be applied to practical heating system.

Reactive dual magnetron sputtering for large area application

International Nuclear Information System (INIS)

Struempfel, J.

2002-01-01

Production lines for large area coating demand high productivity of reactive magnetron sputtering processes. Increased dynamic deposition rates for oxides and nitrides were already obtained by using of highly powered magnetrons in combination with advanced sputter techniques. However, besides high deposition rates the uniformity of such coatings has to be carefully considered. First the basics of reactive sputtering processes and dual magnetron sputtering are summarized. Different methods for process stabilization and control are commonly used for reactive sputtering. The Plasma Emission Monitor (PE M) offers the prerequisite for fast acting process control derived from the in-situ intensity measurements of a spectral line of the sputtered target material. Combined by multiple Plasma Emission Monitor control loops segmented gas manifolds are able to provide excellent thin film uniformity at high deposition rates. The Dual Magnetron allows a broad range of processing by different power supply modes. Medium frequency, DC and pulsed DC power supplies can be used for high quality layers. Whereas the large area coating of highly isolating layers like TiO 2 or SiO 2 is dominated by MF sputtering best results for coating with transparent conductive oxides are obtained by dual DC powering of the dual magnetron arrangement. (Author)

Lactone size dependent reactivity in Candida antarctica lipase B: A molecular dynamics and docking study

NARCIS (Netherlands)

Veld, M.A.J.; Fransson, L.; Palmans, A.R.A.; Meijer, E.W.; Hult, K.

2009-01-01

Size matters: Lactones have extensively been studied as monomers in enzymatic polymerization reactions. Large lactones showed an unexpectedly high reactivity in these reactions. A combination of docking and molecular dynamics studies have been used to explain this high reactivity in terms of

Dynamic Power Management for Portable Hybrid Power-Supply Systems Utilizing Approximate Dynamic Programming

Directory of Open Access Journals (Sweden)

Jooyoung Park

2015-05-01

Full Text Available Recently, the optimization of power flows in portable hybrid power-supply systems (HPSSs has become an important issue with the advent of a variety of mobile systems and hybrid energy technologies. In this paper, a control strategy is considered for dynamically managing power flows in portable HPSSs employing batteries and supercapacitors. Our dynamic power management strategy utilizes the concept of approximate dynamic programming (ADP. ADP methods are important tools in the fields of stochastic control and machine learning, and the utilization of these tools for practical engineering problems is now an active and promising research field. We propose an ADP-based procedure based on optimization under constraints including the iterated Bellman inequalities, which can be solved by convex optimization carried out offline, to find the optimal power management rules for portable HPSSs. The effectiveness of the proposed procedure is tested through dynamic simulations for smartphone workload scenarios, and simulation results show that the proposed strategy can successfully cope with uncertain workload demands.

The Bullwhip Effect on the VMI-Supply Chain Management viaSystem Dynamics Approach: The Supply Chain with Two Suppliers and One Retail Channel

Directory of Open Access Journals (Sweden)

Yahia Zare Mehrjerdi

2016-08-01

Full Text Available This work investigates the effect of different inventory policies of a supply chain model using the system dynamics approach which belongs to the class of Vendor Managed Inventory (VMI, automatic pipeline, inventory and order based production control systems (VMI-APIOBPCS. This work helps management to investigate the effect of different policies such as adding the VMI system or third party logistic (TPL on the whole cost of the supply chain. To this end, this work applies system dynamics in supply chain with two supplier and one retail channel which consists of VMI system. Moreover, this work studies the performance of the proposed model via three metrics: Bullwhip effect; satisfaction of the end-customer; the amount of the whole inventory of chain.

Reactive power and voltage control strategy based on dynamic and adaptive segment for DG inverter

Science.gov (United States)

Zhai, Jianwei; Lin, Xiaoming; Zhang, Yongjun

2018-03-01

The inverter of distributed generation (DG) can support reactive power to help solve the problem of out-of-limit voltage in active distribution network (ADN). Therefore, a reactive voltage control strategy based on dynamic and adaptive segment for DG inverter is put forward to actively control voltage in this paper. The proposed strategy adjusts the segmented voltage threshold of Q(U) droop curve dynamically and adaptively according to the voltage of grid-connected point and the power direction of adjacent downstream line. And then the reactive power reference of DG inverter can be got through modified Q(U) control strategy. The reactive power of inverter is controlled to trace the reference value. The proposed control strategy can not only control the local voltage of grid-connected point but also help to maintain voltage within qualified range considering the terminal voltage of distribution feeder and the reactive support for adjacent downstream DG. The scheme using the proposed strategy is compared with the scheme without the reactive support of DG inverter and the scheme using the Q(U) control strategy with constant segmented voltage threshold. The simulation results suggest that the proposed method has a significant improvement on solving the problem of out-of-limit voltage, restraining voltage variation and improving voltage quality.

Ionic liquids: radiation chemistry, solvation dynamics and reactivity patterns

International Nuclear Information System (INIS)

Wishart, J.F.; Funston, A.M.; Szreder, T.

2006-01-01

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of energy production, chemical industry and environmental applications. Pulse radiolysis of [R 4 N][NTf 2 ] [R 4 N][N(CN) 2 ], and [R 4 P][N(CN) 2 ] ionic liquids produces solvated electrons that absorb over a broad range in the near infrared and persisting for hundreds of nanoseconds. Systematic cation variation shows that solvated electron's spectroscopic properties depend strongly on the lattice structure of the ionic liquid. Very early in our radiolysis studies it became evident that

Pollution source localization in an urban water supply network based on dynamic water demand.

Science.gov (United States)

Yan, Xuesong; Zhu, Zhixin; Li, Tian

2017-10-27

Urban water supply networks are susceptible to intentional, accidental chemical, and biological pollution, which pose a threat to the health of consumers. In recent years, drinking-water pollution incidents have occurred frequently, seriously endangering social stability and security. The real-time monitoring for water quality can be effectively implemented by placing sensors in the water supply network. However, locating the source of pollution through the data detection obtained by water quality sensors is a challenging problem. The difficulty lies in the limited number of sensors, large number of water supply network nodes, and dynamic user demand for water, which leads the pollution source localization problem to an uncertainty, large-scale, and dynamic optimization problem. In this paper, we mainly study the dynamics of the pollution source localization problem. Previous studies of pollution source localization assume that hydraulic inputs (e.g., water demand of consumers) are known. However, because of the inherent variability of urban water demand, the problem is essentially a fluctuating dynamic problem of consumer's water demand. In this paper, the water demand is considered to be stochastic in nature and can be described using Gaussian model or autoregressive model. On this basis, an optimization algorithm is proposed based on these two dynamic water demand change models to locate the pollution source. The objective of the proposed algorithm is to find the locations and concentrations of pollution sources that meet the minimum between the analogue and detection values of the sensor. Simulation experiments were conducted using two different sizes of urban water supply network data, and the experimental results were compared with those of the standard genetic algorithm.

Basic study on dynamic reactive-power control method with PV output prediction for solar inverter

Directory of Open Access Journals (Sweden)

Ryunosuke Miyoshi

2016-01-01

Full Text Available To effectively utilize a photovoltaic (PV system, reactive-power control methods for solar inverters have been considered. Among the various methods, the constant-voltage control outputs less reactive power compared with the other methods. We have developed a constant-voltage control to reduce the reactive-power output. However, the developed constant-voltage control still outputs unnecessary reactive power because the control parameter is constant in every waveform of the PV output. To reduce the reactive-power output, we propose a dynamic reactive-power control method with a PV output prediction. In the proposed method, the control parameter is varied according to the properties of the predicted PV waveform. In this study, we performed numerical simulations using a distribution system model, and we confirmed that the proposed method reduces the reactive-power output within the voltage constraint.

Mechanism of supply chain coordination cased on dynamic capability framework-the mediating role of manufacturing capabilities

Directory of Open Access Journals (Sweden)

Tiantian Gao

2014-10-01

Full Text Available Purpose: A critical issue has been absent from the conversation on supply chain coordination: how supply chain coordination influence the enterprise performance. This research proposes a new vision to research the performance mechanism of supply chain coordination capability as a dynamic capability. Manufacturing capabilities are existed as mediating role. Design/methodology/approach: Data from International Manufacturing Strategy Survey in 2009 is used to verify the mediating model by hierarchical regression analysis. Findings: The results show that supply chain coordination impacts the enterprise performance positively and indirect impacts the enterprise performance through quality, cost, flexibility. Research implications: This study presents an overview of the impact of supply chain coordination and manufacturing capabilities on enterprise performance, giving grasp for further research of the relationships that exist between them. Originality/value: This finding integrates insights from previous research in dynamic capability framework and supply chain management into a generalization and extension of the performance mechanism in manufacturing enterprises.

A System Dynamics Modeling of Water Supply and Demand in Las Vegas Valley

Science.gov (United States)

Parajuli, R.; Kalra, A.; Mastino, L.; Velotta, M.; Ahmad, S.

2017-12-01

The rise in population and change in climate have posed the uncertainties in the balance between supply and demand of water. The current study deals with the water management issues in Las Vegas Valley (LVV) using Stella, a system dynamics modeling software, to model the feedback based relationship between supply and demand parameters. Population parameters were obtained from Center for Business and Economic Research while historical water demand and conservation practices were modeled as per the information provided by local authorities. The water surface elevation of Lake Mead, which is the prime source of water supply to the region, was modeled as the supply side whereas the water demand in LVV was modeled as the demand side. The study was done from the period of 1989 to 2049 with 1989 to 2012 as the historical one and the period from 2013 to 2049 as the future period. This study utilizes Coupled Model Intercomparison Project data sets (2013-2049) (CMIP3&5) to model different future climatic scenarios. The model simulates the past dynamics of supply and demand, and then forecasts the future water budget for the forecasted future population and future climatic conditions. The results can be utilized by the water authorities in understanding the future water status and hence plan suitable conservation policies to allocate future water budget and achieve sustainable water management.

Static and Dynamic Pricing Strategies in a Closed-Loop Supply Chain with Reference Quality Effects

Directory of Open Access Journals (Sweden)

Zhichao Zhang

2018-01-01

Full Text Available Remanufacturing of returned products has been increasingly recognized in industries as an effective approach to face environmental responsibility, government regulations, and increased awareness of consumers. In this paper, we address a closed-loop supply chain (CLSC in which the manufacturer produces the brand-new products, as well as the remanufactured goods while the retailer sells these products to customers. We consider several different scenarios: the manufacturer and the retailer adopt a steady-state price or a dynamic price with reference quality effects in a centralized case; either, neither or both the manufacturer and the retailer price dynamically with reference quality effects, respectively, in a decentralized model. We solve the problem with the retailer recycling the sold copies and deduce the optimal pricing strategies while the manufacturer in charge of recovering the used items in such a CLSC. The result shows that dynamic pricing strategies are much more profitable for the supply chain and its members when compared with pricing statically; the dynamic pricing strategies with time-varying quality characterized by reference quality are more suited to a long-term and cooperative closed-loop supply chain. Moreover, the optimal recycling fraction relies on the recovery cost coefficient and proves to be uniform despite adopting a dynamic price and quality in all distinct cases.

Optimization of a dynamic supply portfolio considering risks and discount’s constraints

Directory of Open Access Journals (Sweden)

Masoud Rabbani

2014-01-01

Full Text Available Purpose: Nowadays finding reliable suppliers in the global supply chains has become so important for success, because reliable suppliers would lead to a reliable supply and besides that orders of customer are met effectively . Yet, there is little empirical evidence to support this view, hence the purpose of this paper is to fill this need by considering risk in order to find the optimum supply portfolio. Design/methodology/approach: This paper proposes a multi objective model for the supplier selection portfolio problem that uses conditional value at risk (CVaR criteria to control the risks of delayed, disrupted and defected supplies via scenario analysis. Also we consider discount’s constraints which are common assumptions in supplier selection problems. The proposed approach is capable of determining the optimal supply portfolio by calculating value-at-risk and minimizing conditional value-at-risk. In this study the Reservation Level driven Tchebycheff Procedure (RLTP which is one of the reference point methods, is used to solve small size of our model through coding in GAMS. As our model is NP-hard; a meta-heuristic approach, Non-dominated Sorting Genetic Algorithm (NSGA which is one of the most efficient methods for optimizing multi objective models, is applied to solve large scales of our model. Findings and Originality/value: In order to find a dynamic supply portfolio, we developed a Mixed Integer Linear Programming (MILP model which contains two objectives. One objective minimizes the cost and the other minimizes the risks of delayed, disrupted and defected supplies. CVaR is used as the risk controlling method which emphases on low-probability, high-consequence events. Discount option as a common offer from suppliers is also implanted in the proposed model. Our findings show that the proposed model can help in optimization of a dynamic supplier selection portfolio with controlling the corresponding risks for large scales of real word

A new computational method for reactive power market clearing

International Nuclear Information System (INIS)

Zhang, T.; Elkasrawy, A.; Venkatesh, B.

2009-01-01

After deregulation of electricity markets, ancillary services such as reactive power supply are priced separately. However, unlike real power supply, procedures for costing and pricing reactive power supply are still evolving and spot markets for reactive power do not exist as of now. Further, traditional formulations proposed for clearing reactive power markets use a non-linear mixed integer programming formulation that are difficult to solve. This paper proposes a new reactive power supply market clearing scheme. Novelty of this formulation lies in the pricing scheme that rewards transformers for tap shifting while participating in this market. The proposed model is a non-linear mixed integer challenge. A significant portion of the manuscript is devoted towards the development of a new successive mixed integer linear programming (MILP) technique to solve this formulation. The successive MILP method is computationally robust and fast. The IEEE 6-bus and 300-bus systems are used to test the proposed method. These tests serve to demonstrate computational speed and rigor of the proposed method. (author)

Local Dynamic Reactive Power for Correction of System Voltage Problems

Energy Technology Data Exchange (ETDEWEB)

Kueck, John D [ORNL; Rizy, D Tom [ORNL; Li, Fangxing [ORNL; Xu, Yan [ORNL; Li, Huijuan [University of Tennessee, Knoxville (UTK); Adhikari, Sarina [ORNL; Irminger, Philip [ORNL

2008-12-01

Distribution systems are experiencing outages due to a phenomenon known as local voltage collapse. Local voltage collapse is occurring in part because modern air conditioner compressor motors are much more susceptible to stalling during a voltage dip than older motors. These motors can stall in less than 3 cycles (.05s) when a fault, such as on the sub-transmission system, causes voltage to sag to 70 to 60%. The reasons for this susceptibility are discussed in the report. During the local voltage collapse, voltages are depressed for a period of perhaps one or two minutes. There is a concern that these local events are interacting together over larger areas and may present a challenge to system reliability. An effective method of preventing local voltage collapse is the use of voltage regulation from Distributed Energy Resources (DER) that can supply or absorb reactive power. DER, when properly controlled, can provide a rapid correction to voltage dips and prevent motor stall. This report discusses the phenomenon and causes of local voltage collapse as well as the control methodology we have developed to counter voltage sag. The problem is growing because of the use of low inertia, high efficiency air conditioner (A/C) compressor motors and because the use of electric A/C is growing in use and becoming a larger percentage of system load. A method for local dynamic voltage regulation is discussed which uses reactive power injection or absorption from local DER. This method is independent, rapid, and will not interfere with conventional utility system voltage control. The results of simulations of this method are provided. The method has also been tested at the ORNL s Distributed Energy Communications and Control (DECC) Laboratory using our research inverter and synchronous condenser. These systems at the DECC Lab are interconnected to an actual distribution system, the ORNL distribution system, which is fed from TVA s 161kV sub-transmission backbone. The test results

The READY program: Building a global potential energy surface and reactive dynamic simulations for the hydrogen combustion.

Science.gov (United States)

Mogo, César; Brandão, João

2014-06-30

READY (REActive DYnamics) is a program for studying reactive dynamic systems using a global potential energy surface (PES) built from previously existing PESs corresponding to each of the most important elementary reactions present in the system. We present an application to the combustion dynamics of a mixture of hydrogen and oxygen using accurate PESs for all the systems involving up to four oxygen and hydrogen atoms. Results at the temperature of 4000 K and pressure of 2 atm are presented and compared with model based on rate constants. Drawbacks and advantages of this approach are discussed and future directions of research are pointed out. Copyright © 2014 Wiley Periodicals, Inc.

Effects of loading reactivity at dynamic state on wave of neutrons in burst reactor

International Nuclear Information System (INIS)

Gao Hui; Liu Xiaobo; Fan Xiaoqiang

2013-01-01

Based on the point reactor model, the program for simulating the burst of reactors, including delay neutron, thermal feedback and reactivity of rod, was developed. The program proves to be suitable to burst reactor by experimental data. The program can describe the process of neutron-intensity change in burst reactors. With the program, the parameters of burst (wave of burst, power of peak and reactivity of reactor) under the condition of dynamic reactivity can be calculated. The calculated result demonstrates that the later the burst is initiated, the greater its power of peak and yield are and that the maximum yield coordinates with the yield under static state. (authors)

Stability of the Supply Chain Using System Dynamics Simulation and the Accumulated Deviations from Equilibrium

Directory of Open Access Journals (Sweden)

Luis Rabelo

2011-01-01

Full Text Available We propose and demonstrate a new methodology to stabilize systems with complex dynamics like the supply chain. This method is based on the accumulated deviations from equilibrium (ADE. It is most beneficial for controlling system dynamic models characterized by multiple types of delays, many interacting variables, and feedback processes. We employ the classical version of particle swarm optimization as the optimization approach due to its performance in multidimensional space, stochastic properties, and global reach. We demonstrate the effectiveness of our method based on ADE using a manufacturing-supply-chain case study.

Modelling the Effects of Parking Charge and Supply Policy Using System Dynamics Method

Directory of Open Access Journals (Sweden)

Zhenyu Mei

2017-01-01

Full Text Available Reasonable parking charge and supply policy are essential for the regular operation of the traffic in city center. This paper develops an evaluation model for parking policies using system dynamics. A quantitative study is conducted to examine the effects of parking charge and supply policy on traffic speed. The model, which is composed of three interrelated subsystems, first summarizes the travel cost of each travel mode and then calibrates the travel choice model through the travel mode subsystem. Finally, the subsystem that evaluates the state of traffic forecasts future car speed based on bureau of public roads (BPR function and generates new travel cost until the entire model reaches a steady state. The accuracy of the model is verified in Hangzhou Wulin business district. The related error of predicted speed is only 2.2%. The results indicate that the regular pattern of traffic speed and parking charge can be illustrated using the proposed model based on system dynamics, and the model infers that reducing the parking supply in core area will increase its congestion level and, under certain parking supply conditions, there exists an interval of possible pricing at which the service reaches a level that is fairly stable.

System dynamics research of remanufacturing closed-loop supply chain dominated by the third party.

Science.gov (United States)

Miao, Shidi; Wang, Tengfei; Chen, Deyun

2017-04-01

With the rapid development of the electronic information industry in recent years, electronic products are being updated faster and faster, and e-waste recycling has become a common problem around the world. Firstly, this article contrasts recycling at home and abroad using the predicament of Midea Corp. Based on a closed-loop supply chain with the system dynamics method, a model is constructed and simulated. In this model, the collection point coverage rate is introduced to adjust the e-waste recycling rate dynamically. Aiming at a recycling mode dominated by the third party of the closed-loop supply chain, the article mainly discusses the impact on the sales rate and market share of the recycling model by third-party enterprises and compares the total revenue of all supply chains. Simulation results show that the model is more effective and optimal than the traditional recycling model.

Improvement of the dynamic response of the ITER Reactive Power Compensation system

International Nuclear Information System (INIS)

Finotti, Claudio; Gaio, Elena; Song, Inho; Tao, Jun; Benfatto, Ivone

2015-01-01

Highlights: • The slow response reasons of the classic ITER Reactive Power Compensation (RPC) control are explained. • The dynamic behaviors of the ac/dc converter and of the RPC are characterized. • New control concept to speed up the RPC response is developed. • Good performance of the new RPC control is verified even during fast transient conditions. - Abstract: The ITER ac/dc conversion system can absorb a total active and reactive power up to 500 MW and 950 Mvar, respectively. The Reactive Power Compensation (RPC) system is rated for a nominal power of 750 Mvar necessary to comply with the allowable reactive power limit value from the grid of 200 Mvar. This system is currently under construction and is based on Static Var Compensation technology with Thyristor Controlled Reactor (TCR) and Tuned Filters. The RPC has to minimize the demand of reactive power from the grid; its control is based on a feed-forward method, where the corrective input is the measurement of the reactive power consumption of the ac/dc converters, derived from the 50 Hz component of the Fast Fourier Transform (FFT) of the three-phase voltages and currents. The delay introduced by the FFT calculation and the slow response of the TCR could make the response speed of the RPC not sufficient to face fast variations of the reactive power demand and therefore in this paper a new controller of the RPC able to overcome this shortcoming is proposed and evaluated. It is based on the calculation of the predicted consumption of the reactive power by using the voltage reference signals coming from the Plasma Control System and the measurements of the dc current of the ac/dc converters and of the 66 kV busbar voltage, and on the speed up of the RPC control by introducing a lead–lag transfer function.

Improvement of the dynamic response of the ITER Reactive Power Compensation system

Energy Technology Data Exchange (ETDEWEB)

Finotti, Claudio, E-mail: claudio.finotti@igi.cnr.it [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Gaio, Elena [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Song, Inho; Tao, Jun; Benfatto, Ivone [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France)

2015-10-15

Highlights: • The slow response reasons of the classic ITER Reactive Power Compensation (RPC) control are explained. • The dynamic behaviors of the ac/dc converter and of the RPC are characterized. • New control concept to speed up the RPC response is developed. • Good performance of the new RPC control is verified even during fast transient conditions. - Abstract: The ITER ac/dc conversion system can absorb a total active and reactive power up to 500 MW and 950 Mvar, respectively. The Reactive Power Compensation (RPC) system is rated for a nominal power of 750 Mvar necessary to comply with the allowable reactive power limit value from the grid of 200 Mvar. This system is currently under construction and is based on Static Var Compensation technology with Thyristor Controlled Reactor (TCR) and Tuned Filters. The RPC has to minimize the demand of reactive power from the grid; its control is based on a feed-forward method, where the corrective input is the measurement of the reactive power consumption of the ac/dc converters, derived from the 50 Hz component of the Fast Fourier Transform (FFT) of the three-phase voltages and currents. The delay introduced by the FFT calculation and the slow response of the TCR could make the response speed of the RPC not sufficient to face fast variations of the reactive power demand and therefore in this paper a new controller of the RPC able to overcome this shortcoming is proposed and evaluated. It is based on the calculation of the predicted consumption of the reactive power by using the voltage reference signals coming from the Plasma Control System and the measurements of the dc current of the ac/dc converters and of the 66 kV busbar voltage, and on the speed up of the RPC control by introducing a lead–lag transfer function.

Mood-Reactive Self-Esteem and Depression Vulnerability: Person-Specific Symptom Dynamics via Smart Phone Assessment

Science.gov (United States)

Clasen, Peter C.; Fisher, Aaron J.; Beevers, Christopher G.

2015-01-01

Cognitive theories of depression suggest that mood-reactive self-esteem, a pattern of cognitive reactivity where low self-esteem is temporally dependent on levels of sadness, represents vulnerability for depression. Few studies have directly tested this hypothesis, particularly using intensive data collection methods (i.e., experience sampling) required to capture the temporal dynamics of sadness and self-esteem as they unfold naturally, over time. In this study we used participants’ smartphones to collect multiple daily ratings of sadness and self-esteem over three weeks, in the real world. We then applied dynamic factor modeling to explore theoretically driven hypotheses about the temporal dependency of self-esteem on sadness (i.e., mood-reactive self-esteem) and its relationship to indices of depression vulnerability both contemporaneously (e.g., rumination, sad mood persistence) and prospectively (e.g., future symptomatology). In sum, individuals who demonstrated mood-reactive self-esteem reported higher levels of rumination at baseline, more persistent sad mood over three weeks, and increased depression symptoms at the end of three weeks above and beyond a trait-like index of self-esteem. The integration of smartphone assessment and person-specific analytics employed in this study offers an exiting new avenue to advance the study and treatment of depression. PMID:26131724

Mood-Reactive Self-Esteem and Depression Vulnerability: Person-Specific Symptom Dynamics via Smart Phone Assessment.

Directory of Open Access Journals (Sweden)

Peter C Clasen

Full Text Available Cognitive theories of depression suggest that mood-reactive self-esteem, a pattern of cognitive reactivity where low self-esteem is temporally dependent on levels of sadness, represents vulnerability for depression. Few studies have directly tested this hypothesis, particularly using intensive data collection methods (i.e., experience sampling required to capture the temporal dynamics of sadness and self-esteem as they unfold naturally, over time. In this study we used participants' smartphones to collect multiple daily ratings of sadness and self-esteem over three weeks, in the real world. We then applied dynamic factor modeling to explore theoretically driven hypotheses about the temporal dependency of self-esteem on sadness (i.e., mood-reactive self-esteem and its relationship to indices of depression vulnerability both contemporaneously (e.g., rumination, sad mood persistence and prospectively (e.g., future symptomatology. In sum, individuals who demonstrated mood-reactive self-esteem reported higher levels of rumination at baseline, more persistent sad mood over three weeks, and increased depression symptoms at the end of three weeks above and beyond a trait-like index of self-esteem. The integration of smartphone assessment and person-specific analytics employed in this study offers an exiting new avenue to advance the study and treatment of depression.

Mood-Reactive Self-Esteem and Depression Vulnerability: Person-Specific Symptom Dynamics via Smart Phone Assessment.

Science.gov (United States)

Clasen, Peter C; Fisher, Aaron J; Beevers, Christopher G

2015-01-01

Cognitive theories of depression suggest that mood-reactive self-esteem, a pattern of cognitive reactivity where low self-esteem is temporally dependent on levels of sadness, represents vulnerability for depression. Few studies have directly tested this hypothesis, particularly using intensive data collection methods (i.e., experience sampling) required to capture the temporal dynamics of sadness and self-esteem as they unfold naturally, over time. In this study we used participants' smartphones to collect multiple daily ratings of sadness and self-esteem over three weeks, in the real world. We then applied dynamic factor modeling to explore theoretically driven hypotheses about the temporal dependency of self-esteem on sadness (i.e., mood-reactive self-esteem) and its relationship to indices of depression vulnerability both contemporaneously (e.g., rumination, sad mood persistence) and prospectively (e.g., future symptomatology). In sum, individuals who demonstrated mood-reactive self-esteem reported higher levels of rumination at baseline, more persistent sad mood over three weeks, and increased depression symptoms at the end of three weeks above and beyond a trait-like index of self-esteem. The integration of smartphone assessment and person-specific analytics employed in this study offers an exiting new avenue to advance the study and treatment of depression.

Effects of irradiation distance on supply of reactive oxygen species to the bottom of a Petri dish filled with liquid by an atmospheric O{sub 2}/He plasma jet

Energy Technology Data Exchange (ETDEWEB)

Kawasaki, Toshiyuki, E-mail: kawasaki@nbu.ac.jp; Kusumegi, Shota; Kudo, Akihiro; Sakanoshita, Tomohiro; Tsurumaru, Takuya; Sato, Akihiro [Department of Mechanical and Electrical Engineering, Nippon Bunri University, Oita, Oita 870-0397 (Japan); Uchida, Giichiro [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Koga, Kazunori; Shiratani, Masaharu [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka, Fukuoka 819-0395 (Japan)

2016-05-07

The impact of irradiation distances on plasma jet-induced specific effects on the supply of reactive oxygen species (ROS) to the bottom of a Petri dish filled with liquid was investigated using a KI-starch gel reagent that can be employed as a ROS indicator even in water. O{sub 3} exposure experiments without plasma irradiation were also performed to elucidate the specific effects of the plasma jet. Relative concentrations of ROS transported to the bottom were evaluated using absorbance measurements. The results indicated that ROS supply to the bottom is markedly enhanced by the plasma jet irradiation at shorter irradiation distances, whereas similar results could not be obtained for the O{sub 3} exposure. In these cases, the liquid mixing in the depth direction was also enhanced by the plasma jet irradiation only, and the supply of reactive atomic oxygen to the liquid surface was markedly increased as well.

Long-term dynamics of dissolved organic carbon: implications for drinking water supply.

Science.gov (United States)

Ledesma, José L J; Köhler, Stephan J; Futter, Martyn N

2012-08-15

Surface waters are the main source of drinking water in many regions. Increasing organic carbon concentrations are a cause for concern in Nordic countries since both dissolved and particulate organic carbon can transport contaminants and adversely affect drinking water treatment processes. We present a long-term study of dynamics of total (particulate and dissolved) organic carbon (TOC) concentrations in the River Fyris. This river supplies drinking water to approximately 200000 people in Uppsala, Sweden. The River Fyris is a main tributary to Lake Mälaren, which supplies drinking water to approximately 2 million people in the greater Stockholm area. Utilities responsible for drinking water supply in both Uppsala and Stockholm have expressed concerns about possible increases in TOC. We evaluate organic carbon dynamics within the Fyris catchment by calculating areal mass exports using observed TOC concentrations and modeled flows and by modeling dissolved organic carbon (as a proxy for TOC) using the dynamic, process based INCA-C model. Exports of TOC from the catchment ranged from 0.8 to 5.8 g m(-2) year(-1) in the period 1995-2010. The variation in annual exports was related to climatic variability which influenced seasonality and amount of runoff. Exports and discharge uncoupled at the end of 2008. A dramatic increase in TOC concentrations was observed in 2009, which gradually declined in 2010-2011. INCA-C successfully reproduced the intra- and inter-annual variation in concentrations during 1996-2008 and 2010-2011 but failed to capture the anomalous increase in 2009. We evaluated a number of hypotheses to explain the anomaly in 2009 TOC values, ultimately none proved satisfactory. We draw two main conclusions: there is at least one unknown or unmeasured process controlling or influencing surface water TOC and INCA-C can be used as part of the decision-making process for current and future use of rivers for drinking water supply. Copyright © 2012 Elsevier B

Dynamic analysis of compact helical system power supply and designs of its upgrade

International Nuclear Information System (INIS)

Tanahashi, S.; Yamada, S.

1991-09-01

Computed dynamic waveforms are compared with measured ones for the power supply of the Compact Helical System (CHS) during 1.5T operation and found to be in good agreement. On the basis of these results, designs for the upgraded power supply for 2T operation are discussed in the two cases, with and without power consumption for additional heating. In the former case, the additional heating power is supplied from the ac generator that powers the CHS coils. Electric voltages and currents in the electric circuit are shown for both cases. These designs show the possibility for 2T operation by addition of some components without changing the ratings of existing components. (author)

Challenging bullwhip effect dynamics with electronically enabled-supply chain management systems

Directory of Open Access Journals (Sweden)

Thokozani Patmond Mbhele

2016-11-01

Full Text Available The bullwhip effect shows the dynamics of accumulating order rate that exceeds the tentatively stable actual demand rate. This paper aimed to assess the relative role of e-SCM systems as consumer demand orders cascading upstream supply chain network. The study’s population, consisting of the managers (senior and functional levels including supervisory level (non-managerial from retail sales, logistics, warehousing, marketing, manufacturing and IT hubs organisations, comprised of 460 respondents. In order to achieve the paper’s objective, the researcher developed and distributed a survey questionnaire and collected and analysed the data using Statistical Package for the Social Sciences (SPSS. The empirical results from the study reveal that business-to-business information technology (B2BIT diffusion frequencies have an effect on supply chain performance and e-SCM implementation promotes connectivity among supply chain partners to entrench commitment of the exchanged demand order information to mitigate the bullwhip effect

Reactors Dynamic analysis Due to Reactivity of The RSG-Gas at One Line Cooling Mode

International Nuclear Information System (INIS)

Hastuti, Endiah Puji

2003-01-01

In the frame of minimizing the operation-cost, operation mode using one line cooling system is being evaluated. Maximum reactor power has been determined and steady state and LOFA transient analysis have also been done. To complete those analyses, the reactivity analysis was done by means of a core dynamic and thermal hydraulic code, PARET-ANL. Accident simulation was done. by a ramp reactivity accident due to control rod withdrawal. Reactivity analysis was carried out at two power range i.e. low and high power level, by imposing one line mode reactor protection limits. The results show that technically, the RSG-Gas can be operated safely using one line mode

Iterative analysis of cerebrovascular reactivity dynamic response by temporal decomposition.

Science.gov (United States)

van Niftrik, Christiaan Hendrik Bas; Piccirelli, Marco; Bozinov, Oliver; Pangalu, Athina; Fisher, Joseph A; Valavanis, Antonios; Luft, Andreas R; Weller, Michael; Regli, Luca; Fierstra, Jorn

2017-09-01

To improve quantitative cerebrovascular reactivity (CVR) measurements and CO 2 arrival times, we present an iterative analysis capable of decomposing different temporal components of the dynamic carbon dioxide- Blood Oxygen-Level Dependent (CO 2 -BOLD) relationship. Decomposition of the dynamic parameters included a redefinition of the voxel-wise CO 2 arrival time, and a separation from the vascular response to a stepwise increase in CO 2 (Delay to signal Plateau - DTP) and a decrease in CO 2 (Delay to signal Baseline -DTB). Twenty-five (normal) datasets, obtained from BOLD MRI combined with a standardized pseudo-square wave CO 2 change, were co-registered to generate reference atlases for the aforementioned dynamic processes to score the voxel-by-voxel deviation probability from normal range. This analysis is further illustrated in two subjects with unilateral carotid artery occlusion using these reference atlases. We have found that our redefined CO 2 arrival time resulted in the best data fit. Additionally, excluding both dynamic BOLD phases (DTP and DTB) resulted in a static CVR, that is maximal response, defined as CVR calculated only over a normocapnic and hypercapnic calibrated plateau. Decomposition and novel iterative modeling of different temporal components of the dynamic CO 2 -BOLD relationship improves quantitative CVR measurements.

Reactive power compensator

Science.gov (United States)

El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.; Chen, Mingliang; Andexler, George; Huang, Tony

1992-01-01

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

Reactive power compensator

Energy Technology Data Exchange (ETDEWEB)

El-Sharkawi, Mohamed A. (Renton, WA); Venkata, Subrahmanyam S. (Woodinville, WA); Chen, Mingliang (Kirkland, WA); Andexler, George (Everett, WA); Huang, Tony (Seattle, WA)

1992-01-01

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

Nanomaterials under extreme environments: A study of structural and dynamic properties using reactive molecular dynamics simulations

Science.gov (United States)

Shekhar, Adarsh

Nanotechnology is becoming increasingly important with the continuing advances in experimental techniques. As researchers around the world are trying to expand the current understanding of the behavior of materials at the atomistic scale, the limited resolution of equipment, both in terms of time and space, act as roadblocks to a comprehensive study. Numerical methods, in general and molecular dynamics, in particular act as able compliment to the experiments in our quest for understanding material behavior. In this research work, large scale molecular dynamics simulations to gain insight into the mechano-chemical behavior under extreme conditions of a variety of systems with many real world applications. The body of this work is divided into three parts, each covering a particular system: 1) Aggregates of aluminum nanoparticles are good solid fuel due to high flame propagation rates. Multi-million atom molecular dynamics simulations reveal the mechanism underlying higher reaction rate in a chain of aluminum nanoparticles as compared to an isolated nanoparticle. This is due to the penetration of hot atoms from reacting nanoparticles to an adjacent, unreacted nanoparticle, which brings in external heat and initiates exothermic oxidation reactions. 2) Cavitation bubbles readily occur in fluids subjected to rapid changes in pressure. We use billion-atom reactive molecular dynamics simulations on a 163,840-processor BlueGene/P supercomputer to investigate chemical and mechanical damages caused by shock-induced collapse of nanobubbles in water near amorphous silica. Collapse of an empty nanobubble generates high-speed nanojet, resulting in the formation of a pit on the surface. The pit contains a large number of silanol groups and its volume is found to be directly proportional to the volume of the nanobubble. The gas-filled bubbles undergo partial collapse and consequently the damage on the silica surface is mitigated. 3) The structure and dynamics of water confined in

A Method of Dynamic Extended Reactive Power Optimization in Distribution Network Containing Photovoltaic-Storage System

Science.gov (United States)

Wang, Wu; Huang, Wei; Zhang, Yongjun

2018-03-01

The grid-integration of Photovoltaic-Storage System brings some undefined factors to the network. In order to make full use of the adjusting ability of Photovoltaic-Storage System (PSS), this paper puts forward a reactive power optimization model, which are used to construct the objective function based on power loss and the device adjusting cost, including energy storage adjusting cost. By using Cataclysmic Genetic Algorithm to solve this optimization problem, and comparing with other optimization method, the result proved that: the method of dynamic extended reactive power optimization this article puts forward, can enhance the effect of reactive power optimization, including reducing power loss and device adjusting cost, meanwhile, it gives consideration to the safety of voltage.

An introduction to reactive power compensation for wind farms

Energy Technology Data Exchange (ETDEWEB)

Nigim, K.A. [Waterloo Univ., Ont. (Canada). Dept. of Electrical and Computer Engineering; Cairo Univ., Giza (Egypt). Faculty of Engineering; Zobaa, A.F.; El Amin, I. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Electrical Engineering

2005-07-01

The paper summarises the refereed contributions of seven articles reviewed for publication in the IJETP - Special Issue on 'Reactive compensation for wind farms'. The main goal of the special issue is to provide a forum to exchange information on the reactive power compensation requirements for wind farms and introducing possible price mechanisms for today's deregulated power industry. Uncompensated reactive power causes stress on the hosting utility grid as well as added expenses, which create in difficulties for power purchasing agreements from independent wind energy producers. Wind power producers need to comply with the hosting utility grid interconnection standards, e.g., voltage and frequency, as well as to provide controllable active and reactive sources of power. Active power supply is mainly dependent on the potential of wind power produced and the turbine design. Reactive power demand on the other hand depends on the conversion devices and the recovered power quantity fed to the grid. Static Var Compensators (SVC), Unified Power Quality Conditioners (UPQC), Unified Power Flow Controllers (UPFC), and the Distributed Static Synchronous Compensators (DSTATCOM) are all new emerging devices aimed at regulating the reactive power requirements. The excellent controllability of these devices has paved the way to flexible and dynamic controllers that are capable of regulating the flow of active and reactive power components. These devices are now suggested for the control of the reactive power requirement of wind generators. Studies have demonstrated acceptable voltage stabilisation results. This has increased the penetration level of wind power into existing distribution networks in many countries. (Author)

An introduction to reactive power compensation for wind farms

International Nuclear Information System (INIS)

Nigim, K.A.; Cairo Univ., Giza; Zobaa, A.F.; El Amin, I.

2005-01-01

The paper summarises the refereed contributions of seven articles reviewed for publication in the IJETP - Special Issue on 'Reactive compensation for wind farms'. The main goal of the special issue is to provide a forum to exchange information on the reactive power compensation requirements for wind farms and introducing possible price mechanisms for today's deregulated power industry. Uncompensated reactive power causes stress on the hosting utility grid as well as added expenses, which create in difficulties for power purchasing agreements from independent wind energy producers. Wind power producers need to comply with the hosting utility grid interconnection standards, e.g., voltage and frequency, as well as to provide controllable active and reactive sources of power. Active power supply is mainly dependent on the potential of wind power produced and the turbine design. Reactive power demand on the other hand depends on the conversion devices and the recovered power quantity fed to the grid. Static Var Compensators (SVC), Unified Power Quality Conditioners (UPQC), Unified Power Flow Controllers (UPFC), and the Distributed Static Synchronous Compensators (DSTATCOM) are all new emerging devices aimed at regulating the reactive power requirements. The excellent controllability of these devices has paved the way to flexible and dynamic controllers that are capable of regulating the flow of active and reactive power components. These devices are now suggested for the control of the reactive power requirement of wind generators. Studies have demonstrated acceptable voltage stabilisation results. This has increased the penetration level of wind power into existing distribution networks in many countries. (Author)

Core reactivity estimation in space reactors using recurrent dynamic networks

Science.gov (United States)

Parlos, Alexander G.; Tsai, Wei K.

1991-01-01

A recurrent multilayer perceptron network topology is used in the identification of nonlinear dynamic systems from only the input/output measurements. The identification is performed in the discrete time domain, with the learning algorithm being a modified form of the back propagation (BP) rule. The recurrent dynamic network (RDN) developed is applied for the total core reactivity prediction of a spacecraft reactor from only neutronic power level measurements. Results indicate that the RDN can reproduce the nonlinear response of the reactor while keeping the number of nodes roughly equal to the relative order of the system. As accuracy requirements are increased, the number of required nodes also increases, however, the order of the RDN necessary to obtain such results is still in the same order of magnitude as the order of the mathematical model of the system. It is believed that use of the recurrent MLP structure with a variety of different learning algorithms may prove useful in utilizing artificial neural networks for recognition, classification, and prediction of dynamic systems.

Dynamic Balanced Scorecard for companies in the business field of power supply; Dynamic Balanced Scorecard fuer Unternehmen im Geschaeftsfeld der dezentralen Energieversorgung

Energy Technology Data Exchange (ETDEWEB)

Hollmann, M.; Roy, I. [Paderborn Univ. (Germany). Lehrstuhl fuer Nachhaltige Energiekonzepte

2006-06-19

Due to deregulation and liberalisation of the power market and due to the opting out of the nuclear energy, the decentralized power supply increasingly gains in importance in comparison to the classical power supply. Thus, the entrepreneur who wants to engage in the decentralized power supply needs a management tool for conversion and supervision his strategy. A pertinent means for this already is the Dynamic Balanced Scorecard. By means of an evaluation of a simple balanced scorecard, the entrepreneur realizes his vision and strategy in order to determine the success-critical factors. These success-critical factors are related together in a causal chain. By this, the entrepreneur can recognize, what has to be done in order to act successfully on the market, and in order to secure the success on a long-term basis. The modelling of the Dynamic balanced Scorecard enables the examination of the corporate strategy, before it is implemented in the enterprise. Thus, the entrepreneur saves time and minimizes the corporate risk.

Further development of the Dynamic Control Assemblies Worth Measurement Method for Advanced Reactivity Computers

International Nuclear Information System (INIS)

Petenyi, V.; Strmensky, C.; Jagrik, J.; Minarcin, M.; Sarvaic, I.

2005-01-01

The dynamic control assemblies worth measurement technique is a quick method for validation of predicted control assemblies worth. The dynamic control assemblies worth measurement utilize space-time corrections for the measured out of core ionization chamber readings calculated by DYN 3D computer code. The space-time correction arising from the prompt neutron density redistribution in the measured ionization chamber reading can be directly applied in the advanced reactivity computer. The second correction concerning the difference of spatial distribution of delayed neutrons can be calculated by simulation the measurement procedure by dynamic version of the DYN 3D code. In the paper some results of dynamic control assemblies worth measurement applied for NPP Mochovce are presented (Authors)

Growth dynamics of reactive-sputtering-deposited AlN films

International Nuclear Information System (INIS)

Auger, M.A.; Vazquez, L.; Sanchez, O.; Jergel, M.; Cuerno, R.; Castro, M.

2005-01-01

We have studied the surface kinetic roughening of AlN films grown on Si(100) substrates by dc reactive sputtering within the framework of the dynamic scaling theory. Films deposited under the same experimental conditions for different growth times were analyzed by atomic force microscopy and x-ray diffraction. The AlN films display a (002) preferred orientation. We have found two growth regimes with a crossover time of 36 min. In the first regime, the growth dynamics is unstable and the films present two types of textured domains, well textured and randomly oriented, respectively. In contrast, in the second regime the films are homogeneous and well textured, leading to a relative stabilization of the surface roughness characterized by a growth exponent β=0.37±0.03. In this regime a superrough scaling behavior is found with the following exponents: (i) Global exponents: roughness exponent α=1.2±0.2 and β=0.37±0.03 and coarsening exponent 1/z=0.32±0.05; (ii) local exponents: α loc =1, β loc =0.32±0.01. The differences between the growth modes are found to be related to the different main growth mechanisms dominating their growth dynamics: sticking anisotropy and shadowing, respectively

Efficient dynamic scarcity pricing in urban water supply

Science.gov (United States)

Lopez-Nicolas, Antonio; Pulido-Velazquez, Manuel; Rougé, Charles; Harou, Julien J.; Escriva-Bou, Alvar

2017-04-01

Water pricing is a key instrument for water demand management. Despite the variety of existing strategies for urban water pricing, urban water rates are often far from reflecting the real value of the resource, which increases with water scarcity. Current water rates do not bring any incentive to reduce water use in water scarcity periods, since they do not send any signal to the users of water scarcity. In California, the recent drought has spurred the implementation of drought surcharges and penalties to reduce residential water use, although it is not a common practice yet. In Europe, the EU Water Framework Directive calls for the implementation of new pricing policies that assure the contribution of water users to the recovery of the cost of water services (financial instrument) while providing adequate incentives for an efficient use of water (economic instrument). Not only financial costs should be recovered but also environmental and resource (opportunity) costs. A dynamic pricing policy is efficient if the prices charged correspond to the marginal economic value of water, which increases with water scarcity and is determined by the value of water for all alternative uses in the basin. Therefore, in the absence of efficient water markets, measuring the opportunity costs of scarce water can only be achieved through an integrated basin-wide hydroeconomic simulation approach. The objective of this work is to design a dynamic water rate for urban water supply accounting for the seasonal marginal value of water in the basin, related to water scarcity. The dynamic pricing policy would send to the users a signal of the economic value of the resource when water is scarce, therefore promoting more efficient water use. The water rate is also designed to simultaneously meet the expected basic requirements for water tariffs: revenue sufficiency (cost recovery) and neutrality, equity and affordability, simplicity and efficiency. A dynamic increasing block rate (IBR

Projecting surgeon supply using a dynamic model.

Science.gov (United States)

Fraher, Erin P; Knapton, Andy; Sheldon, George F; Meyer, Anthony; Ricketts, Thomas C

2013-05-01

To develop a projection model to forecast the head count and full-time equivalent supply of surgeons by age, sex, and specialty in the United States from 2009 to 2028. The search for the optimal number and specialty mix of surgeons to care for the United States population has taken on increased urgency under health care reform. Expanded insurance coverage and an aging population will increase demand for surgical and other medical services. Accurate forecasts of surgical service capacity are crucial to inform the federal government, training institutions, professional associations, and others charged with improving access to health care. The study uses a dynamic stock and flow model that simulates future changes in numbers and specialty type by factoring in changes in surgeon demographics and policy factors. : Forecasts show that overall surgeon supply will decrease 18% during the period form 2009 to 2028 with declines in all specialties except colorectal, pediatric, neurological surgery, and vascular surgery. Model simulations suggest that none of the proposed changes to increase graduate medical education currently under consideration will be sufficient to offset declines. The length of time it takes to train surgeons, the anticipated decrease in hours worked by surgeons in younger generations, and the potential decreases in graduate medical education funding suggest that there may be an insufficient surgeon workforce to meet population needs. Existing maldistribution patterns are likely to be exacerbated, leading to delayed or lost access to time-sensitive surgical procedures, particularly in rural areas.

Myopic versus Far-Sighted Behaviors in Dynamic Supply Chain Coordination through Advertising with Reference Price Effect

Directory of Open Access Journals (Sweden)

Yafei Zu

2017-01-01

Full Text Available To better understand the different effects of the myopic and far-sighted behaviors on the advertising coordination in dynamic supply chain, this paper takes the reference price effect into consideration and formulates four differential game models for the two-level supply chain composed of a manufacturer and a retailer in the situation of Stackelberg game. In our models, the market demand is assumed to be affected by the goodwill, reference price, and the advertising investment, in which the advertising investment can promote the construction of goodwill and such goodwill can further enhance the reference price. The results show that the participating members in the supply chain should invest more in advertisement to improve the goodwill and the relative reference price reflected in the minds of consumers. A far-sighted manufacturer will invest more in the advertisement and charge a higher wholesale price regardless of the behavior choice of the retailer. However, such kind of ignorance leads to different results on the retail pricing strategies of the retailer. The numerical analyses are given in the end to verify the effectiveness of the conclusions which provide the theoretical support to the dynamic supply chain coordination in practice.

Dynamic impact of the structure of the supply chain of perishable foods on logistics performance and food security

Energy Technology Data Exchange (ETDEWEB)

Castro, Javier Arturo Orjuela; Jaimes, Wilson Adarme

2017-07-01

Understanding how the structure affects logistical performance and food security is critical in the supply chains of perishable foods (PFSC). This research proposes a system dynamics model to analyze the effects of structures: lean, agile, flexible, responsive and resilient, in the overall performance and of each agent of the PFSC. Design/methodology/approach: Using a system dynamics model and design of experiments it is studied how the different structures and their combination, affect the behavior of inventory, transportation, responsiveness, efficiency, availability and quality-safety of the fresh fruits supply chain and each echelon. Findings: The studies of supply chains have been done for each structure in an independent way; investigations are scarce in supply chains of perishable foods. The structures modeled in this research do not show the better performance in all the metrics of the chain, neither in all agents for each structure. The above implies the presence of trade-offs. Research limitations/implications: The results show the need to investigate mixed structures with the FPSC´s own characteristics; the model can be applied in other supply chains of perishable foods. Practical implications: Management by combining structures in the FFSC, improves logistics performance and contributes to food security. Social implications: The agents of the FFSC can apply the structures found in this study, to improve their logistics performance and the food security. Originality/value: The dynamics of individual and combined structures were identified, which constitutes a contribution to the discussion in the literature of such problems for FFSC. The model includes six echelons: farmers, wholesalers, agro-industry, third-party logistics operators and retailers. The dynamic contemplates deterioration rate to model perishability and others losses.

Dynamic impact of the structure of the supply chain of perishable foods on logistics performance and food security

Directory of Open Access Journals (Sweden)

Javier Arturo Orjuela Castro

2017-10-01

Full Text Available Purpose: Understanding how the structure affects logistical performance and food security is critical in the supply chains of perishable foods (PFSC. This research proposes a system dynamics model to analyze the effects of structures: lean, agile, flexible, responsive and resilient, in the overall performance and of each agent of the PFSC. Design/methodology/approach: Using a system dynamics model and design of experiments it is studied how the different structures and their combination, affect the behavior of inventory, transportation, responsiveness, efficiency, availability and quality-safety of the fresh fruits supply chain and each echelon. Findings: The studies of supply chains have been done for each structure in an independent way; investigations are scarce in supply chains of perishable foods. The structures modeled in this research do not show the better performance in all the metrics of the chain, neither in all agents for each structure. The above implies the presence of trade-offs. Research limitations/implications: The results show the need to investigate mixed structures with the FPSC´s own characteristics; the model can be applied in other supply chains of perishable foods. Practical implications: Management by combining structures in the FFSC, improves logistics performance and contributes to food security. Social implications: The agents of the FFSC can apply the structures found in this study, to improve their logistics performance and the food security. Originality/value: The dynamics of individual and combined structures were identified, which constitutes a contribution to the discussion in the literature of such problems for FFSC. The model includes six echelons: farmers, wholesalers, agro-industry, third-party logistics operators and retailers. The dynamic contemplates deterioration rate to model perishability and others losses.

Dynamic impact of the structure of the supply chain of perishable foods on logistics performance and food security

International Nuclear Information System (INIS)

Castro, Javier Arturo Orjuela; Jaimes, Wilson Adarme

2017-01-01

Understanding how the structure affects logistical performance and food security is critical in the supply chains of perishable foods (PFSC). This research proposes a system dynamics model to analyze the effects of structures: lean, agile, flexible, responsive and resilient, in the overall performance and of each agent of the PFSC. Design/methodology/approach: Using a system dynamics model and design of experiments it is studied how the different structures and their combination, affect the behavior of inventory, transportation, responsiveness, efficiency, availability and quality-safety of the fresh fruits supply chain and each echelon. Findings: The studies of supply chains have been done for each structure in an independent way; investigations are scarce in supply chains of perishable foods. The structures modeled in this research do not show the better performance in all the metrics of the chain, neither in all agents for each structure. The above implies the presence of trade-offs. Research limitations/implications: The results show the need to investigate mixed structures with the FPSC´s own characteristics; the model can be applied in other supply chains of perishable foods. Practical implications: Management by combining structures in the FFSC, improves logistics performance and contributes to food security. Social implications: The agents of the FFSC can apply the structures found in this study, to improve their logistics performance and the food security. Originality/value: The dynamics of individual and combined structures were identified, which constitutes a contribution to the discussion in the literature of such problems for FFSC. The model includes six echelons: farmers, wholesalers, agro-industry, third-party logistics operators and retailers. The dynamic contemplates deterioration rate to model perishability and others losses.

Dynamic Pricing and Supply Coordination with Reimbursement Contract under Random Yield and Demand

Directory of Open Access Journals (Sweden)

Guo Li

2013-01-01

Full Text Available This paper investigates the dynamic pricing and supply chain coordination in a decentralized system that consists of one supplier and one manufacturer, in which both the market demand and production yield are stochastic. We show that the centralized expected profit is jointly concave in the production quantity and order quantity when the price is ex-ante selected. We also derive the equilibrium strategies in the decentralized system and prove that the entire profit of supply chain is inevitably lower than that under centralized system. Based on this, we propose a reimbursement contract to coordinate the decentralized supply chain so as to achieve the maximized profit. It is worth mentioning that, under reimbursement contract, the equilibrium production and order quantities are irrelevant to the manufacturer's risk sharing coefficient but are only determined by the supplier’s risk sharing coefficient.

Study of the IPR-R1 dynamics by means of reactivity pseudo-aleatory excitations

International Nuclear Information System (INIS)

Roedel, G.

1983-01-01

Aiming to demonstrate the feasibility of using the reactor noise neutronic analysis tecniques a dynamic model was developed for the IPR-R1 reactor at CDTN. This model allows reactivity feedback, due to the variations of fuel and coolant temperature. The system was excited by the variations of reactivity modulated by a pseudo aleatory binary sequence and its answer was measured by means of the fluctuactions dround the stationary power. The model developed and the technique used was tested, and the values of the system parameters obtained from the adjustment of the theoretical and experimental transfer function were compared to another, obtained from independent process. (E.G.) [pt

Towards a dynamic assessment of raw materials criticality: Linking agent-based demand — With material flow supply modelling approaches

International Nuclear Information System (INIS)

Knoeri, Christof; Wäger, Patrick A.; Stamp, Anna; Althaus, Hans-Joerg; Weil, Marcel

2013-01-01

Emerging technologies such as information and communication-, photovoltaic- or battery technologies are expected to increase significantly the demand for scarce metals in the near future. The recently developed methods to evaluate the criticality of mineral raw materials typically provide a ‘snapshot’ of the criticality of a certain material at one point in time by using static indicators both for supply risk and for the impacts of supply restrictions. While allowing for insights into the mechanisms behind the criticality of raw materials, these methods cannot account for dynamic changes in products and/or activities over time. In this paper we propose a conceptual framework intended to overcome these limitations by including the dynamic interactions between different possible demand and supply configurations. The framework integrates an agent-based behaviour model, where demand emerges from individual agent decisions and interaction, into a dynamic material flow model, representing the materials' stocks and flows. Within the framework, the environmental implications of substitution decisions are evaluated by applying life-cycle assessment methodology. The approach makes a first step towards a dynamic criticality assessment and will enhance the understanding of industrial substitution decisions and environmental implications related to critical metals. We discuss the potential and limitation of such an approach in contrast to state-of-the-art methods and how it might lead to criticality assessments tailored to the specific circumstances of single industrial sectors or individual companies. - Highlights: ► Current criticality assessment methods provide a ‘snapshot’ at one point in time. ► They do not account for dynamic interactions between demand and supply. ► We propose a conceptual framework to overcomes these limitations. ► The framework integrates an agent-based behaviour model with a dynamic material flow model. ► The approach proposed makes

Macroeconomic susceptibility, inflation, and aggregate supply

Science.gov (United States)

Hawkins, Raymond J.

2017-03-01

We unify aggregate-supply dynamics as a time-dependent susceptibility-mediated relationship between inflation and aggregate economic output. In addition to representing well various observations of inflation-output dynamics this parsimonious formalism provides a straightforward derivation of popular representations of aggregate-supply dynamics and a natural basis for economic-agent expectations as an element of inflation formation. Our formalism also illuminates questions of causality and time-correlation that challenge central banks for whom aggregate-supply dynamics is a key constraint in their goal of achieving macroeconomic stability.

Control Theory Concepts Applied to Retail Supply Chain: A System Dynamics Modeling Environment Study

Directory of Open Access Journals (Sweden)

Balaji Janamanchi

2013-01-01

Full Text Available Control theory concepts have been long used to successfully manage and optimize complex systems. Using system dynamics (SD modeling methodology, which is continuous deterministic simulation modeling methodology, we apply control theory concepts to develop a suitable performance functional (or objective function that optimizes the performance of a retail supply chain. The focus is to develop insights for inventory management to prevent stock-outs and unfilled orders and to fill customer orders at the lowest possible cost to supply chain partners under different scenarios, in a two-player supplier-retailer supply chain. Moderate levels of inventory, defining appropriate performance functional, appear to be crucial in choosing the right policies for managing retail supply chain systems. The study also demonstrated how multiple objectives can be combined in a single performance functional (or objective function by carefully assigning suitable weights to the components of objectives based on their priority and the existence of possible trade off opportunities.

China’s Rare Earths Supply Forecast in 2025: A Dynamic Computable General Equilibrium Analysis

Directory of Open Access Journals (Sweden)

Jianping Ge

2016-09-01

Full Text Available The supply of rare earths in China has been the focus of significant attention in recent years. Due to changes in regulatory policies and the development of strategic emerging industries, it is critical to investigate the scenario of rare earth supplies in 2025. To address this question, this paper constructed a dynamic computable equilibrium (DCGE model to forecast the production, domestic supply, and export of China’s rare earths in 2025. Based on our analysis, production will increase by 10.8%–12.6% and achieve 116,335–118,260 tons of rare-earth oxide (REO in 2025, based on recent extraction control during 2011–2016. Moreover, domestic supply and export will be 75,081–76,800 tons REO and 38,797–39,400 tons REO, respectively. The technological improvements on substitution and recycling will significantly decrease the supply and mining activities of rare earths. From a policy perspective, we found that the elimination of export regulations, including export quotas and export taxes, does have a negative impact on China’s future domestic supply of rare earths. The policy conflicts between the increase in investment in strategic emerging industries, and the increase in resource and environmental taxes on rare earths will also affect China’s rare earths supply in the future.

Reactivity on the Web

OpenAIRE

Bailey, James; Bry, François; Eckert, Michael; Patrânjan, Paula Lavinia

2005-01-01

Reactivity, the ability to detect simple and composite events and respond in a timely manner, is an essential requirement in many present-day information systems. With the emergence of new, dynamic Web applications, reactivity on the Web is receiving increasing attention. Reactive Web-based systems need to detect and react not only to simple events but also to complex, real-life situations. This paper introduces XChange, a language for programming reactive behaviour on the Web,...

Implementation of system dynamic simulation method to optimize profit in supply chain network of vegetable product

Science.gov (United States)

Tama, I. P.; Akbar, Z.; Eunike, A.

2018-04-01

Vegetables are categorized as a perishable product, which is a product with short lifespan thus requires proper handling and planning to reduce losses caused by the short lifespan. In order to reduce the losses, coordination among the players in the supply chain is required. On the other hand, the decision in the supply chain of vegetables and other farming products in the traditional market of developing country is independent among the players. This research is conducted by using System Dynamic Simulation method to develop model and scenario by coordinating the supply quantity amongst players in the supply chain. The scenarios are developed based on newsboy inventory model. This study aims to compare scenarios combining tiers involved in coordination program. The result shows that coordination in supply chain increases total supply chain profit, although there will always be players who experienced decrements in profit. The scenario of coordination among the farmer, the distributor, and the wholesaler resulted in the highest increase in total supply chain profit compared to other coordination scenarios, with an increased value of 10.49%.

Predicting Reactive Transport Dynamics in Carbonates using Initial Pore Structure

Science.gov (United States)

Menke, H. P.; Nunes, J. P. P.; Blunt, M. J.

2017-12-01

Understanding rock-fluid interaction at the pore-scale is imperative for accurate predictive modelling of carbon storage permanence. However, coupled reactive transport models are computationally expensive, requiring either a sacrifice of resolution or high performance computing to solve relatively simple geometries. Many recent studies indicate that initial pore structure many be the dominant mechanism in determining the dissolution regime. Here we investigate how well the initial pore structure is predictive of distribution and amount of dissolution during reactive flow using particle tracking on the initial image. Two samples of carbonate rock with varying initial pore space heterogeneity were reacted with reservoir condition CO2-saturated brine and scanned dynamically during reactive flow at a 4-μm resolution between 4 and 40 times using 4D X-ray micro-tomography over the course of 1.5 hours using μ-CT. Flow was modelled on the initial binarized image using a Navier-Stokes solver. Particle tracking was then run on the velocity fields, the streamlines were traced, and the streamline density was calculated both on a voxel-by-voxel and a channel-by-channel basis. The density of streamlines was then compared to the amount of dissolution in subsequent time steps during reaction. It was found that for the flow and transport regimes studied, the streamline density distribution in the initial image accurately predicted the dominant pathways of dissolution and gave good indicators of the type of dissolution regime that would later develop. This work suggests that the eventual reaction-induced changes in pore structure are deterministic rather than stochastic and can be predicted with high resolution imaging of unreacted rock.

Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

KAUST Repository

Pump, Eva; Viger-Gravel, Jasmine; Abou-Hamad, Edy; Samantaray, Manoja; Hamzaoui, Bilel; Gurinov, Andrei; Anjum, Dalaver H.; Gajan, David; Lesage, Anne; Bendjeriou-Sedjerari, Anissa; Emsley, Lyndon; Basset, Jean-Marie

2016-01-01

Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.

Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

KAUST Repository

Pump, Eva

2016-08-15

Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.

Supply circuit for and dynamic characteristics of discharge in a nitrogen laser

Energy Technology Data Exchange (ETDEWEB)

Sidorov, Yu L; Sukhanov, A N

1978-03-01

The dynamic characteristics of discharge in a nitrogen laser with an output radiation power at the 1 MW level were measured in an experiment under pressures ranging from 30 to 350 mm Hg. At the same time, the design and the performance of a supply circuit on the basis of a Blumlein line as pumping source were evaluated. The results of this study indicate that the practically attainable efficiency, which depends on the characteristics impedance of the discharge circuit, can be increased from 0.07 to 0.1% with a two-stage laser, by shortening the pump discharge and supplying most energy to the second stage at higher E/p ratios. Multistage high-power lasers operating in the generator-amplifier mode with high gain in the active medium are thus feasible without the need for expensive optical decoupling of stages.

Methodology for Simulation and Analysis of Complex Adaptive Supply Network Structure and Dynamics Using Information Theory

Directory of Open Access Journals (Sweden)

Joshua Rodewald

2016-10-01

Full Text Available Supply networks existing today in many industries can behave as complex adaptive systems making them more difficult to analyze and assess. Being able to fully understand both the complex static and dynamic structures of a complex adaptive supply network (CASN are key to being able to make more informed management decisions and prioritize resources and production throughout the network. Previous efforts to model and analyze CASN have been impeded by the complex, dynamic nature of the systems. However, drawing from other complex adaptive systems sciences, information theory provides a model-free methodology removing many of those barriers, especially concerning complex network structure and dynamics. With minimal information about the network nodes, transfer entropy can be used to reverse engineer the network structure while local transfer entropy can be used to analyze the network structure’s dynamics. Both simulated and real-world networks were analyzed using this methodology. Applying the methodology to CASNs allows the practitioner to capitalize on observations from the highly multidisciplinary field of information theory which provides insights into CASN’s self-organization, emergence, stability/instability, and distributed computation. This not only provides managers with a more thorough understanding of a system’s structure and dynamics for management purposes, but also opens up research opportunities into eventual strategies to monitor and manage emergence and adaption within the environment.

Analysis of shallow-groundwater dynamic responses to water supply change in the Haihe River plain

Science.gov (United States)

Lin, Z.; Lin, W.; Pengfei, L.

2015-05-01

When the middle route of the South-to-North Water Diversion Project is completed, the water supply pattern of the Haihe River plain in North China will change significantly due to the replenishment of water sources and groundwater-exploitation control. The water-cycle-simulation model - MODCYCLE, has been used in simulating the groundwater dynamic balance for 2001-2010. Then different schemes of water supply in 2020 and 2030 were set up to quantitatively simulate the shallow-groundwater dynamic responses in the future. The results show that the total shallow-groundwater recharge is mainly raised by the increases in precipitation infiltration and surface-water irrigation infiltration. Meanwhile, the decrease of groundwater withdrawal contributes to reduce the total discharge. The recharge-discharge structure of local groundwater was still in a negative balance but improved gradually. The shallow-groundwater level in most parts was still falling before 2030, but more slowly. This study can benefit the rational exploitation of water resources in the Haihe River plain.

Supply reliability and dynamic safety analysis of an alternative energy supply chain

DEFF Research Database (Denmark)

Herbert-Hansen, Zaza Nadja Lee; Markert, Frank; Jacobsen, Peter

2016-01-01

This paper focuses on the integration of risk and supply chain modelling by means of analysing a case concerning a Hydrogen Refuelling Station in Berlin. It presents a framework that can analyse an energy supply chain and at the same time enables easy reporting and presentation of various results...

Unfunded pensions and endogenous labor supply

DEFF Research Database (Denmark)

Andersen, Torben M.; Bhattacharya, Joydeep

A classic result in dynamic public economics, dating back to Aaron (1966) and Samuelson (1975), states that there is no welfare rationale for PAYG pensions in a dynamically-efficient neoclassical economy with exogenous labor supply. This paper argues that this result, under the fairly-mild restri......A classic result in dynamic public economics, dating back to Aaron (1966) and Samuelson (1975), states that there is no welfare rationale for PAYG pensions in a dynamically-efficient neoclassical economy with exogenous labor supply. This paper argues that this result, under the fairly......-mild restriction that the old be no less risk-averse than the young, extends to a neoclassical economy with endogenous labor supply....

Urban cholera transmission hotspots and their implications for reactive vaccination: evidence from Bissau city, Guinea bissau.

Directory of Open Access Journals (Sweden)

Andrew S Azman

Full Text Available Use of cholera vaccines in response to epidemics (reactive vaccination may provide an effective supplement to traditional control measures. In Haiti, reactive vaccination was considered but, until recently, rejected in part due to limited global supply of vaccine. Using Bissau City, Guinea-Bissau as a case study, we explore neighborhood-level transmission dynamics to understand if, with limited vaccine and likely delays, reactive vaccination can significantly change the course of a cholera epidemic.We fit a spatially explicit meta-population model of cholera transmission within Bissau City to data from 7,551 suspected cholera cases from a 2008 epidemic. We estimated the effect reactive vaccination campaigns would have had on the epidemic under different levels of vaccine coverage and campaign start dates. We compared highly focused and diffuse strategies for distributing vaccine throughout the city. We found wide variation in the efficiency of cholera transmission both within and between areas of the city. "Hotspots", where transmission was most efficient, appear to drive the epidemic. In particular one area, Bandim, was a necessary driver of the 2008 epidemic in Bissau City. If vaccine supply were limited but could have been distributed within the first 80 days of the epidemic, targeting vaccination at Bandim would have averted the most cases both within this area and throughout the city. Regardless of the distribution strategy used, timely distribution of vaccine in response to an ongoing cholera epidemic can prevent cases and save lives.Reactive vaccination can be a useful tool for controlling cholera epidemics, especially in urban areas like Bissau City. Particular neighborhoods may be responsible for driving a city's cholera epidemic; timely and targeted reactive vaccination at such neighborhoods may be the most effective way to prevent cholera cases both within that neighborhood and throughout the city.

Chemical reactivity and spectroscopy explored from QM/MM molecular dynamics simulations using the LIO code

Science.gov (United States)

Marcolongo, Juan P.; Zeida, Ari; Semelak, Jonathan A.; Foglia, Nicolás O.; Morzan, Uriel N.; Estrin, Dario A.; González Lebrero, Mariano C.; Scherlis, Damián A.

2018-03-01

In this work we present the current advances in the development and the applications of LIO, a lab-made code designed for density functional theory calculations in graphical processing units (GPU), that can be coupled with different classical molecular dynamics engines. This code has been thoroughly optimized to perform efficient molecular dynamics simulations at the QM/MM DFT level, allowing for an exhaustive sampling of the configurational space. Selected examples are presented for the description of chemical reactivity in terms of free energy profiles, and also for the computation of optical properties, such as vibrational and electronic spectra in solvent and protein environments.

Estimating temperature reactivity coefficients by experimental procedures combined with isothermal temperature coefficient measurements and dynamic identification

International Nuclear Information System (INIS)

Tsuji, Masashi; Aoki, Yukinori; Shimazu, Yoichiro; Yamasaki, Masatoshi; Hanayama, Yasushi

2006-01-01

A method to evaluate the moderator coefficient (MTC) and the Doppler coefficient through experimental procedures performed during reactor physics tests of PWR power plants is proposed. This method combines isothermal temperature coefficient (ITC) measurement experiments and reactor power transient experiments at low power conditions for dynamic identification. In the dynamic identification, either one of temperature coefficients can be determined in such a way that frequency response characteristics of the reactivity change observed by a digital reactivity meter is reproduced from measured data of neutron count rate and the average coolant temperature. The other unknown coefficient can also be determined by subtracting the coefficient obtained from the dynamic identification from ITC. As the proposed method can directly estimate the Doppler coefficient, the applicability of the conventional core design codes to predict the Doppler coefficient can be verified for new types of fuels such as mixed oxide fuels. The digital simulation study was carried out to show the feasibility of the proposed method. The numerical analysis showed that the MTC and the Doppler coefficient can be estimated accurately and even if there are uncertainties in the parameters of the reactor kinetics model, the accuracies of the estimated values are not seriously impaired. (author)

Towards a dynamic assessment of raw materials criticality: linking agent-based demand--with material flow supply modelling approaches.

Science.gov (United States)

Knoeri, Christof; Wäger, Patrick A; Stamp, Anna; Althaus, Hans-Joerg; Weil, Marcel

2013-09-01

Emerging technologies such as information and communication-, photovoltaic- or battery technologies are expected to increase significantly the demand for scarce metals in the near future. The recently developed methods to evaluate the criticality of mineral raw materials typically provide a 'snapshot' of the criticality of a certain material at one point in time by using static indicators both for supply risk and for the impacts of supply restrictions. While allowing for insights into the mechanisms behind the criticality of raw materials, these methods cannot account for dynamic changes in products and/or activities over time. In this paper we propose a conceptual framework intended to overcome these limitations by including the dynamic interactions between different possible demand and supply configurations. The framework integrates an agent-based behaviour model, where demand emerges from individual agent decisions and interaction, into a dynamic material flow model, representing the materials' stocks and flows. Within the framework, the environmental implications of substitution decisions are evaluated by applying life-cycle assessment methodology. The approach makes a first step towards a dynamic criticality assessment and will enhance the understanding of industrial substitution decisions and environmental implications related to critical metals. We discuss the potential and limitation of such an approach in contrast to state-of-the-art methods and how it might lead to criticality assessments tailored to the specific circumstances of single industrial sectors or individual companies. Copyright © 2013 Elsevier B.V. All rights reserved.

System Dynamics Modeling on Integrated Supply Chain Management of Potato Agribusiness

Directory of Open Access Journals (Sweden)

Lukman Hakim

2017-12-01

Full Text Available The objectives of this study is to design a model of integrated supply chain management of potato agribusiness in an effort to increase revenue and bargaining position of farmers in Aceh Province. The method applied to achieve these objectives was the methodology of system dynamics. Formulation of the models was conducted by using Vensim DSS Software, followed by simulation. The result of this study showed the role of five major scenarios which were important to actualize the integrated supply chain management of potato agribusiness in Aceh Province, those were: scenario 1, increasing the productive land area, resulting in the increasing of production volume; scenario 2, using the certified potato seed named “umbi G2”, generating the higher level of production; scenario 3, providing the certified potato seed based on the needs, showing that the quantity of production increased; scenario 4, shortening the payment receivables interval of farmers and cooperatives, which showing the increasing of cash amount; scenario 5, doing certification to the potato from synergistic partnerships farmers, showing the increasing of acceptance, profitability, R/C, and cash.

Algorithms of GPU-enabled reactive force field (ReaxFF) molecular dynamics.

Science.gov (United States)

Zheng, Mo; Li, Xiaoxia; Guo, Li

2013-04-01

Reactive force field (ReaxFF), a recent and novel bond order potential, allows for reactive molecular dynamics (ReaxFF MD) simulations for modeling larger and more complex molecular systems involving chemical reactions when compared with computation intensive quantum mechanical methods. However, ReaxFF MD can be approximately 10-50 times slower than classical MD due to its explicit modeling of bond forming and breaking, the dynamic charge equilibration at each time-step, and its one order smaller time-step than the classical MD, all of which pose significant computational challenges in simulation capability to reach spatio-temporal scales of nanometers and nanoseconds. The very recent advances of graphics processing unit (GPU) provide not only highly favorable performance for GPU enabled MD programs compared with CPU implementations but also an opportunity to manage with the computing power and memory demanding nature imposed on computer hardware by ReaxFF MD. In this paper, we present the algorithms of GMD-Reax, the first GPU enabled ReaxFF MD program with significantly improved performance surpassing CPU implementations on desktop workstations. The performance of GMD-Reax has been benchmarked on a PC equipped with a NVIDIA C2050 GPU for coal pyrolysis simulation systems with atoms ranging from 1378 to 27,283. GMD-Reax achieved speedups as high as 12 times faster than Duin et al.'s FORTRAN codes in Lammps on 8 CPU cores and 6 times faster than the Lammps' C codes based on PuReMD in terms of the simulation time per time-step averaged over 100 steps. GMD-Reax could be used as a new and efficient computational tool for exploiting very complex molecular reactions via ReaxFF MD simulation on desktop workstations. Copyright © 2013 Elsevier Inc. All rights reserved.

Differential Dynamic Evolutionary Model of Emergency Financial Service Supply Chain in Natural Disaster Risk Management

Directory of Open Access Journals (Sweden)

Shujian Ma

2016-01-01

Full Text Available A government-market-public partnership (GMPP could be a feasible arrangement for providing insurance coverage for natural disaster. Firstly, we put forward GMPP management mode. Secondly, the emergency financial service supply chain for natural disaster risk is built from the view of supply chain. Finally, the objective of this paper is to obtain insights into the cooperative and competitive relationship in GMPP system. We establish the cooperative and competitive differential dynamic evolutionary models and prove the existence of equilibrium solutions in order to solve the coordination problems. In conclusion, the equilibrium solutions can be achieved among the insurers, the operating governments, and the public.

Analysis of neutronics and dynamic characteristics with reactivity injection in LBE cooled sub-critical reactor

International Nuclear Information System (INIS)

Chen Sen; Wu Yican; Jin Ming; Chen Zhibin; Bai Yunqing; Zhao Zhumin

2014-01-01

Accelerator Driven Sub-critical System (ADS) has particular neutronics behaviors compared with the critical system. Prompt jump approximation point reactor kinetics equations taken external source into account have been deduced using an approach of prompt jump approximation. And the relationship between injection reactivity and power ampliation has been achieved. In addition, based on the RELAP5 code the prolong development of point reactor kinetics code used into assessing sub-critical system have been promoted. Different sub-criticality (k eff = 0.90, 0.95, 0.97, 0.98 and 0.99) have been assessed in preliminary design of a type of natural circulation cooling sub-critical reactor under conditions of reactivity injection +1 β in one second. It shows that the external source prompt transient approximation method has an accurate solution after injecting reactivity around short time and has a capacity to solve the dynamic equation, and the sub-critical system has an inner stability while the deeper sub-criticality the less impact on the sub-critical system. (authors)

Chemical Reactivity and Spectroscopy Explored From QM/MM Molecular Dynamics Simulations Using the LIO Code

Directory of Open Access Journals (Sweden)

Juan P. Marcolongo

2018-03-01

Full Text Available In this work we present the current advances in the development and the applications of LIO, a lab-made code designed for density functional theory calculations in graphical processing units (GPU, that can be coupled with different classical molecular dynamics engines. This code has been thoroughly optimized to perform efficient molecular dynamics simulations at the QM/MM DFT level, allowing for an exhaustive sampling of the configurational space. Selected examples are presented for the description of chemical reactivity in terms of free energy profiles, and also for the computation of optical properties, such as vibrational and electronic spectra in solvent and protein environments.

Dynamic modeling of the isoamyl acetate reactive distillation process

Directory of Open Access Journals (Sweden)

Ali Syed Sadiq

2017-03-01

Full Text Available The cost-effectiveness of reactive distillation (RD processes makes them highly attractive for industrial applications. However, their preliminary design and subsequent scale-up and operation are challenging. Specifically, the response of RD system during fluctuations in process parameters is of paramount importance to ensure the stability of the whole process. As a result of carrying out simulations using Aspen Plus, it is shown that the RD process for isoamyl acetate production was much more economical than conventional reactor distillation configuration under optimized process conditions due to lower utilities consumption, higher conversion and smaller sizes of condenser and reboiler. Rigorous dynamic modeling of RD system was performed to evaluate its sensitivity to disturbances in critical process parameters; the product flow was quite sensitive to disturbances. Even more sensitive was product composition when the disturbance in heat duties of condenser or reboiler led to a temperature decrease. However, positive disturbance in alcohol feed is of particular concern, which clearly made the system unstable.

Portable digital reactivity meter for power reactors

Energy Technology Data Exchange (ETDEWEB)

Steffen, G [Nuklear-Ingenieur Service G.m.b.H., Hanau (Germany, F.R.)

1977-07-01

A digital reactivity meter has been developed, which can be used for all kinds of kinetic reactivity measurements in PWR's and BWR's. The input signals may be supplied by standard neutron detectors of the reactor. The hardware configuration consists of a minicomputer with ADC and DAC, a 'Silent' terminal and a high speed paper tape reader/punch. It is easily transportable. The reactivity meter solves the inverse kinetics equations for 6 delayed neutron groups, simultaneously for up to 8 logarithmic or linear neutron flux signals. It has been successfully tested at Biblis A PWR and the KRB BWR.

Dynamical nexus of water supply, hydropower and environment based on the modeling of multiple socio-natural processes: from socio-hydrological perspective

Science.gov (United States)

Liu, D.; Wei, X.; Li, H. Y.; Lin, M.; Tian, F.; Huang, Q.

2017-12-01

In the socio-hydrological system, the ecological functions and environmental services, which are chosen to maintain, are determined by the preference of the society, which is making the trade-off among the values of riparian vegetation, fish, river landscape, water supply, hydropower, navigation and so on. As the society develops, the preference of the value will change and the ecological functions and environmental services which are chosen to maintain will change. The aim of the study is to focus on revealing the feedback relationship of water supply, hydropower and environment and the dynamical feedback mechanism at macro-scale, and to establish socio-hydrological evolution model of the watershed based on the modeling of multiple socio-natural processes. The study will aim at the Han River in China, analyze the impact of the water supply and hydropower on the ecology, hydrology and other environment elements, and study the effect on the water supply and hydropower to ensure the ecological and environmental water of the different level. Water supply and ecology are usually competitive. In some reservoirs, hydropower and ecology are synergic relationship while they are competitive in some reservoirs. The study will analyze the multiple mechanisms to implement the dynamical feedbacks of environment to hydropower, set up the quantitative relationship description of the feedback mechanisms, recognize the dominant processes in the feedback relationships of hydropower and environment and then analyze the positive and negative feedbacks in the feedback networks. The socio-hydrological evolution model at the watershed scale will be built and applied to simulate the long-term evolution processes of the watershed of the current situation. Dynamical nexus of water supply, hydropower and environment will be investigated.

Hybrid Electromagnetism-Like Algorithm for Dynamic Supply Chain Network Design under Traffic Congestion and Uncertainty

Directory of Open Access Journals (Sweden)

Javid Jouzdani

2016-01-01

Full Text Available With the constantly increasing pressure of the competitive environment, supply chain (SC decision makers are forced to consider several aspects of business climate. More specifically, they should take into account the endogenous features (e.g., available means of transportation, and the variety of products and exogenous criteria (e.g., the environmental uncertainty, and transportation system conditions. In this paper, a mixed integer nonlinear programming (MINLP model for dynamic design of a supply chain network is proposed. In this model, multiple products and multiple transportation modes, the time value of money, traffic congestion, and both supply-side and demand-side uncertainties are considered. Due to the complexity of such models, conventional solution methods are not applicable; therefore, two hybrid Electromagnetism-Like Algorithms (EMA are designed and discussed for tackling the problem. The numerical results show the applicability of the proposed model and the capabilities of the solution approaches to the MINLP problem.

Trust and Control Dynamics in Agrifood Supply Networks: Communication Strategies for Electronic Transaction Environments

OpenAIRE

Fritz, Melanie; Hausen, Tobias

2006-01-01

Agrifood supply networks are dynamic structures where firms regularly face the need to search for new market partners. A decision for a transaction with a new partner requires the existence of appropriate control and safeguard mechanisms as well as trust to overcome perceived risk and uncertainties. Electronic transaction environments offer new potentials for the identification of new transaction partners. However, trust and control need to be communicated appropriately in electronic transact...

Lean production in improving supply chain performance through hybrid model SCOR 11.0 - system dynamics

Science.gov (United States)

Saleh, Chairul; Fatcha Mubiena, Ghaida; Immawan, Taufiq; Hassan, Azmi

2016-02-01

Supply Chain Operation Reference (SCOR) is a method to measure supply chain serving the business process framework, performance indicators and unique technologies to support communication and collaboration among supply chain partners. The objective of this paper is to measure Supply Chain Management performance by using SCOR version 11.0 for production typology of MTS-MTO in Indonesian Batik Industry. This research combines SCOR's model and System Dynamics in order to predict the complex activities on batik industry. The hybrid SCOR-SD could identify the interaction among five attributes with the associated variables simultaneously. The results are obtained after the performance of lean production application is increased and the targets are achieved, even exceeding the target. For reliability attributes that associated with perfect order fulfilment started from 2015 to 2019 respectively are calculated as 80.06%, 103.53%, 105.58%, 93.76%, and 72.17%. Responsiveness attributes associated with the order fulfilment cycle time, respectively 122.45%, 149.10%, 159.26%, 131.53%, and 119.36%. Attributes associated with the total cost of service charge respectively 93.46%, 93.53%, 93.45%, 93.49, and 93.49%. Attributes associated with cash management assets to cash cycle time in a row were 160%, 153%, 146.3%, 150%, and 126.7%. The latter attribute is agility attributes associated with supply chain flexibility upside respectively 100%, 87.2%, 100%, 82%, and 82%.

Structure of HI-6*sarin-acetylcholinesterase determined by X-ray crystallography and molecular dynamics simulation: reactivator mechanism and design.

Directory of Open Access Journals (Sweden)

Fredrik Ekström

2009-06-01

Full Text Available Organophosphonates such as isopropyl metylphosphonofluoridate (sarin are extremely toxic as they phosphonylate the catalytic serine residue of acetylcholinesterase (AChE, an enzyme essential to humans and other species. Design of effective AChE reactivators as antidotes to various organophosphonates requires information on how the reactivators interact with the phosphonylated AChEs. However, such information has not been available hitherto because of three main challenges. First, reactivators are generally flexible in order to change from the ground state to the transition state for reactivation; this flexibility discourages determination of crystal structures of AChE in complex with effective reactivators that are intrinsically disordered. Second, reactivation occurs upon binding of a reactivator to the phosphonylated AChE. Third, the phosphorous conjugate can develop resistance to reactivation. We have identified crystallographic conditions that led to the determination of a crystal structure of the sarin(nonaged-conjugated mouse AChE in complex with [(E-[1-[(4-carbamoylpyridin-1-ium-1-ylmethoxymethyl]pyridin-2-ylidene]methyl]-oxoazanium dichloride (HI-6 at a resolution of 2.2 A. In this structure, the carboxyamino-pyridinium ring of HI-6 is sandwiched by Tyr124 and Trp286, however, the oxime-pyridinium ring is disordered. By combining crystallography with microsecond molecular dynamics simulation, we determined the oxime-pyridinium ring structure, which shows that the oxime group of HI-6 can form a hydrogen-bond network to the sarin isopropyl ether oxygen, and a water molecule is able to form a hydrogen bond to the catalytic histidine residue and subsequently deprotonates the oxime for reactivation. These results offer insights into the reactivation mechanism of HI-6 and design of better reactivators.

Fringe-controlled biodegradation under dynamic conditions: Quasi 2-D flow-through experiments and reactive-transport modeling

Science.gov (United States)

Eckert, Dominik; Kürzinger, Petra; Bauer, Robert; Griebler, Christian; Cirpka, Olaf A.

2015-01-01

Biodegradation in contaminated aquifers has been shown to be most pronounced at the fringe of contaminant plumes, where mixing of contaminated water and ambient groundwater, containing dissolved electron acceptors, stimulates microbial activity. While physical mixing of contaminant and electron acceptor by transverse dispersion has been shown to be the major bottleneck for biodegradation in steady-state plumes, so far little is known on the effect of flow and transport dynamics (caused, e.g., by a seasonally fluctuating groundwater table) on biodegradation in these systems. Towards this end we performed experiments in quasi-two-dimensional flow-through microcosms on aerobic toluene degradation by Pseudomonas putida F1. Plume dynamics were simulated by vertical alteration of the toluene plume position and experimental results were analyzed by reactive-transport modeling. We found that, even after disappearance of the toluene plume for two weeks, the majority of microorganisms stayed attached to the sediment and regained their full biodegradation potential within two days after reappearance of the toluene plume. Our results underline that besides microbial growth, also maintenance and dormancy are important processes that affect biodegradation performance under transient environmental conditions and therefore deserve increased consideration in future reactive-transport modeling.

Core dynamics analysis for reactivity insertion and loss of coolant flow tests using the HTTR

International Nuclear Information System (INIS)

Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Takeda, Tetsuaki

2007-01-01

The High Temperature engineering Test Reactor (HTTR) is a graphite-moderated and a gas-cooled reactor with a thermal power of 30 MW and a reactor outlet coolant temperature of 950degC (SAITO, 1994). Safety demonstration tests using the HTTR are in progress to verify its inherent safety features and improve the safety technology and design methodology for High-Temperature Gas-cooled Reactors (HTGRs) (TACHIBANA 2002) (NAKAGAWA 2004). The reactivity insertion test is one of the safety demonstration tests for the HTTR. This test simulates the rapid increase in the reactor power by withdrawing the control rod without operating the reactor power control system. In addition, the loss of coolant flow tests has been conducted to simulate the rapid decrease in the reactor power by tripping one, two or all out of three gas circulators. The experimental results have revealed the inherent safety features of HTGRs, such as the negative reactivity feedback effect. The numerical analysis code, which was named ACCORD (TAKAMATSU 2006), was developed to analyze the reactor dynamics including the flow behavior in the HTTR core. We used a conventional method, namely, a one-dimensional flow channel model and reactor kinetics model with a single temperature coefficient, taking into account the temperature changes in the core. However, a slight difference between the analytical and experimental results was observed. Therefore, we have modified this code to use a model with four parallel channels and twenty temperature coefficients in the core. Furthermore, we added another analytical model of the core for calculating the heat conduction between the fuel channels and the core in the case of the loss of coolant flow tests. This paper describes the validation results for the newly developed code using the experimental results of the reactivity insertion test as well as the loss of coolant flow tests by tripping one or two out of three gas circulators. Finally, the pre-analytical result of

Flow and nutrient dynamics in a subterranean estuary (Waquoit Bay, MA, USA) : Field data and reactive transport modeling

NARCIS (Netherlands)

Spiteri, C.; Slomp, C.P.; Charette, M.A.; Tuncay, K.; Meile, C.

2008-01-01

A two-dimensional (2D) reactive transport model is used to investigate the controls on nutrient (NO3-, NH4+, PO4) dynamics in a coastal aquifer. The model couples density-dependent flow to a reaction network which includes oxic degradation of organic matter, denitrification, iron oxide reduction,

System Dynamics Model for VMI&TPL Integrated Supply Chains

Directory of Open Access Journals (Sweden)

Guo Li

2013-01-01

Full Text Available This paper establishes VMI-APIOBPCS II model by extending VMI-APIOBPCS model from serial supply chain to distribution supply chain. Then TPL is introduced to this VMI distribution supply chain, and operational framework and process of VMI&TPL integrated supply chain are analyzed deeply. On this basis VMI-APIOBPCS II model is then changed to VMI&TPL-APIOBPCS model and VMI&TPL integrated operation mode is simulated. Finally, compared with VMI-APIOBPCS model, the TPL’s important role of goods consolidation and risk sharing in VMI&TPL integrated supply chain is analyzed in detail from the aspects of bullwhip effect, inventory level, service level, and so on.

Decision support for green supply chain operations by integrating dynamic simulation and LCA indicators: diaper case study.

Science.gov (United States)

Adhitya, Arief; Halim, Iskandar; Srinivasan, Rajagopalan

2011-12-01

As the issue of environmental sustainability is becoming an important business factor, companies are now looking for decision support tools to assess the fuller picture of the environmental impacts associated with their manufacturing operations and supply chain (SC) activities. Lifecycle assessment (LCA) is widely used to measure the environmental consequences assignable to a product. However, it is usually limited to a high-level snapshot of the environmental implications over the product value chain without consideration of the dynamics arising from the multitiered structure and the interactions along the SC. This paper proposes a framework for green supply chain management by integrating a SC dynamic simulation and LCA indicators to evaluate both the economic and environmental impacts of various SC decisions such as inventories, distribution network configuration, and ordering policy. The advantages of this framework are demonstrated through an industrially motivated case study involving diaper production. Three distinct scenarios are evaluated to highlight how the proposed approach enables integrated decision support for green SC design and operation.

Drop Dynamics and Speciation in Isolation of Metals from Liquid Wastes by Reactive Scavenging

Energy Technology Data Exchange (ETDEWEB)

Arne J. Pearlstein; Alexander Scheeline

2002-08-30

Computational and experimental studies of the motion and dynamics of liquid drops in gas flows were conducted with relevance to reactive scavenging of metals from atomized liquid waste. Navier-Stoke's computations of deformable drops revealed a range of conditions from which prolate drops are expected, and showed how frajectiones of deformable drops undergoing deceleration can be computed. Experimental work focused on development of emission fluorescence, and scattering diagnostics. The instrument developed was used to image drop shapes, soot, and nonaxisymmetric departures from steady flow in a 22kw combustor

From Walras’ auctioneer to continuous time double auctions: a general dynamic theory of supply and demand

Science.gov (United States)

Donier, J.; Bouchaud, J.-P.

2016-12-01

In standard Walrasian auctions, the price of a good is defined as the point where the supply and demand curves intersect. Since both curves are generically regular, the response to small perturbations is linearly small. However, a crucial ingredient is absent of the theory, namely transactions themselves. What happens after they occur? To answer the question, we develop a dynamic theory for supply and demand based on agents with heterogeneous beliefs. When the inter-auction time is infinitely long, the Walrasian mechanism is recovered. When transactions are allowed to happen in continuous time, a peculiar property emerges: close to the price, supply and demand vanish quadratically, which we empirically confirm on the Bitcoin. This explains why price impact in financial markets is universally observed to behave as the square root of the excess volume. The consequences are important, as they imply that the very fact of clearing the market makes prices hypersensitive to small fluctuations.

Additive manufacturing technology in spare parts supply chain

DEFF Research Database (Denmark)

Li, Yao; Jia, Guozhu; Yang, Cheng

2017-01-01

Additive Manufacturing (AM) technology has the potential to significantly improve supply chain dynamics. The purpose of this paper is to investigate the impact of AM on spare parts supply chain. Three supply chain scenarios are investigated in this paper, namely conventional supply chain...

Ancillary reactive power service allocation cost in deregulated markets: a methodology

International Nuclear Information System (INIS)

Hernandez, J. Horacio Tovar; Jimenez-Guzman, Miguel; Gutierrez-Alcaraz, Guillermo

2005-01-01

This paper presents a methodology to allocate reactive power costs in deregulated markets. Reactive power supply service is decomposed into voltage regulation and reactive power spinning reserve. The proposed methodology is based on sensitivities and the postage-stamp method in order to allocate the total costs service among all participants. With the purpose of achieving this goal, the system operator identifies voltage support and/or reactive power requirements, and looks out for suitable providers. One case study is presented here to illustrate the methodology over a simplified southeastern Mexican grid. (Author)

Fringe-controlled biodegradation under dynamic conditions: quasi 2-D flow-through experiments and reactive-transport modeling.

Science.gov (United States)

Eckert, Dominik; Kürzinger, Petra; Bauer, Robert; Griebler, Christian; Cirpka, Olaf A

2015-01-01

Biodegradation in contaminated aquifers has been shown to be most pronounced at the fringe of contaminant plumes, where mixing of contaminated water and ambient groundwater, containing dissolved electron acceptors, stimulates microbial activity. While physical mixing of contaminant and electron acceptor by transverse dispersion has been shown to be the major bottleneck for biodegradation in steady-state plumes, so far little is known on the effect of flow and transport dynamics (caused, e.g., by a seasonally fluctuating groundwater table) on biodegradation in these systems. Towards this end we performed experiments in quasi-two-dimensional flow-through microcosms on aerobic toluene degradation by Pseudomonas putida F1. Plume dynamics were simulated by vertical alteration of the toluene plume position and experimental results were analyzed by reactive-transport modeling. We found that, even after disappearance of the toluene plume for two weeks, the majority of microorganisms stayed attached to the sediment and regained their full biodegradation potential within two days after reappearance of the toluene plume. Our results underline that besides microbial growth, also maintenance and dormancy are important processes that affect biodegradation performance under transient environmental conditions and therefore deserve increased consideration in future reactive-transport modeling. Copyright © 2014 Elsevier B.V. All rights reserved.

Dynamics of tuberculosis transmission with exogenous reinfections and endogenous reactivation

Science.gov (United States)

Khajanchi, Subhas; Das, Dhiraj Kumar; Kar, Tapan Kumar

2018-05-01

We propose and analyze a mathematical model for tuberculosis (TB) transmission to study the role of exogenous reinfection and endogenous reactivation. The model exhibits two equilibria: a disease free and an endemic equilibria. We observe that the TB model exhibits transcritical bifurcation when basic reproduction number R0 = 1. Our results demonstrate that the disease transmission rate β and exogenous reinfection rate α plays an important role to change the qualitative dynamics of TB. The disease transmission rate β give rises to the possibility of backward bifurcation for R0 < 1, and hence the existence of multiple endemic equilibria one of which is stable and another one is unstable. Our analysis suggests that R0 < 1 may not be sufficient to completely eliminate the disease. We also investigate that our TB transmission model undergoes Hopf-bifurcation with respect to the contact rate β and the exogenous reinfection rate α. We conducted some numerical simulations to support our analytical findings.

A system dynamics model based on evolutionary game theory for green supply chain management diffusion among Chinese manufacturers

DEFF Research Database (Denmark)

Tian, Yihui; Govindan, Kannan; Zhu, Qinghua

2014-01-01

In this study, a system dynamics (SD) model is developed to guide the subsidy policies to promote the diffusion of green supply chain management (GSCM) in China. The relationships of stakeholders such as government, enterprises and consumers are analyzed through evolutionary game theory. Finally...

Aggregate Supply and Potential Output

OpenAIRE

Razin, Assaf

2004-01-01

The New-Keynesian aggregate supply derives from micro-foundations an inflation-dynamics model very much like the tradition in the monetary literature. Inflation is primarily affected by: (i) economic slack; (ii) expectations; (iii) supply shocks; and (iv) inflation persistence. This paper extends the New Keynesian aggregate supply relationship to include also fluctuations in potential output, as an additional determinant of the relationship. Implications for monetary rules and to the estimati...

Taskable Reactive Agent Communities

National Research Council Canada - National Science Library

Myers, Karen

2002-01-01

The focus of Taskable Reactive Agent Communities (TRAC) project was to develop mixed-initiative technology to enable humans to supervise and manage teams of agents as they perform tasks in dynamic environments...

Slip reactivation during the 2011 Tohoku earthquake: Dynamic rupture and ground motion simulations

Science.gov (United States)

Galvez, P.; Dalguer, L. A.

2013-12-01

The 2011 Mw9 Tohoku earthquake generated such as vast geophysical data that allows studying with an unprecedented resolution the spatial-temporal evolution of the rupture process of a mega thrust event. Joint source inversion of teleseismic, near-source strong motion and coseismic geodetic data , e.g [Lee et. al, 2011], reveal an evidence of slip reactivation process at areas of very large slip. The slip of snapshots of this source model shows that after about 40 seconds the big patch above to the hypocenter experienced an additional push of the slip (reactivation) towards the trench. These two possible repeating slip exhibited by source inversions can create two waveform envelops well distinguished in the ground motion pattern. In fact seismograms of the KiK-Net Japanese network contained this pattern. For instance a seismic station around Miyagi (MYGH10) has two main wavefronts separated between them by 40 seconds. A possible physical mechanism to explain the slip reactivation could be a thermal pressurization process occurring in the fault zone. In fact, Kanamori & Heaton, (2000) proposed that for large earthquakes frictional melting and fluid pressurization can play a key role of the rupture dynamics of giant earthquakes. If fluid exists in a fault zone, an increase of temperature can rise up the pore pressure enough to significantly reduce the frictional strength. Therefore, during a large earthquake the areas of big slip persuading strong thermal pressurization may result in a second drop of the frictional strength after reaching a certain value of slip. Following this principle, we adopt for slip weakening friction law and prescribe a certain maximum slip after which the friction coefficient linearly drops down again. The implementation of this friction law has been done in the latest unstructured spectral element code SPECFEM3D, Peter et. al. (2012). The non-planar subduction interface has been taken into account and place on it a big asperity patch inside

Molecular dynamics simulation of sodium aluminosilicate glass structures and glass surface-water reactions using the reactive force field (ReaxFF)

Science.gov (United States)

Dongol, R.; Wang, L.; Cormack, A. N.; Sundaram, S. K.

2018-05-01

Reactive potentials are increasingly used to study the properties of glasses and glass water reactions in a reactive molecular dynamics (MD) framework. In this study, we have simulated a ternary sodium aluminosilicate glass and investigated the initial stages of the glass surface-water reactions at 300 K using reactive force field (ReaxFF). On comparison of the simulated glass structures generated using ReaxFF and classical Buckingham potentials, our results show that the atomic density profiles calculated for the surface glass structures indicate a bond-angle distribution dependency. The atomic density profiles also show higher concentrations of non-bridging oxygens (NBOs) and sodium ions at the glass surface. Additionally, we present our results of formation of silanol species and the diffusion of water molecules at the glass surface using ReaxFF.

Energy transfer in reactive and non-reactive H2 + OH collisions

International Nuclear Information System (INIS)

Rashed, O.; Brown, N.J.

1985-04-01

We have used the methods of quasi-classical dynamics to compute energy transfer properties of non-reactive and reactive H 2 + OH collisions. Energy transfer has been investigated as function of translational temperature, reagent rotational energy, and reagent vibrational energy. The energy transfer mechanism is complex with ten types of energy transfer possible, and evidence was found for all types. There is much more exchange between the translational degree of freedom and the H 2 vibrational degree of freedom than there is between translation and OH vibration. Translational energy is transferred to the rotational degrees of freedom of each molecule. There is a greater propensity for the transfer of translation to OH rotation than H 2 rotation. In reactive collisions, increases in reagent translational temperature predominantly appear as vibrational energy in the water molecule. Energy transfer in non-reactive and reactive collisions does not depend strongly on the initial angular momentum in either molecule. In non-reactive collisions, vibrational energy is transferred to translation, to the rotational degree of freedom of the same molecule, and to the rotational and vibrational degrees of freedom of the other molecule. In reactive collisions, the major effect of increasing the vibrational energy in reagent molecules is that, on the average, the vibrational energy of the reagents appears as product vibrational energy. 18 refs., 16 figs., 6 tabs

SAInt – A novel quasi-dynamic model for assessing security of supply in coupled gas and electricity transmission networks

NARCIS (Netherlands)

Pambour, Kwabena Addo; Cakir Erdener, Burcin; Bolado-Lavin, Ricardo; Dijkema, Gerhard P.J.

2017-01-01

The integration of renewable energy sources into existing electric power systems is connected with an increased interdependence between natural gas and electricity transmission networks. To analyse this interdependence and its impact on security of supply, we developed a novel quasi-dynamic

Challenging the planetary boundaries II: Assessing the sustainable global population and phosphate supply, using a systems dynamics assessment model

International Nuclear Information System (INIS)

Sverdrup, Harald U.; Ragnarsdottir, Kristin Vala

2011-01-01

Highlights: → Peak phosphorus supply behaviour. → Recycling essential for phosphorus supply. → Phosphorus supply is connected to food security. - Abstract: A systems dynamics model was developed to assess the planetary boundary for P supply in relation to use by human society. It is concluded that present day use rates and poor recycling rates of P are unsustainable at timescales beyond 100+ a. The predictions made suggest that P will become a scarce and expensive material in the future. The study shows clearly that market mechanisms alone will not be able to secure an efficient use before a large part of the resource will have been allowed to dissipate into the natural environment. It is suggested that population size management and effective recycling measures must be planned long term to avoid unpleasant consequences of hunger and necessary corrections imposed on society by mass balance and thermodynamics.

Equilibrium Model of Discrete Dynamic Supply Chain Network with Random Demand and Advertisement Strategy

Directory of Open Access Journals (Sweden)

Guitao Zhang

2014-01-01

Full Text Available The advertisement can increase the consumers demand; therefore it is one of the most important marketing strategies in the operations management of enterprises. This paper aims to analyze the impact of advertising investment on a discrete dynamic supply chain network which consists of suppliers, manufactures, retailers, and demand markets associated at different tiers under random demand. The impact of advertising investment will last several planning periods besides the current period due to delay effect. Based on noncooperative game theory, variational inequality, and Lagrange dual theory, the optimal economic behaviors of the suppliers, the manufactures, the retailers, and the consumers in the demand markets are modeled. In turn, the supply chain network equilibrium model is proposed and computed by modified project contraction algorithm with fixed step. The effectiveness of the model is illustrated by numerical examples, and managerial insights are obtained through the analysis of advertising investment in multiple periods and advertising delay effect among different periods.

Enhancing Eco-Efficiency of Agro-Products’ Closed-Loop Supply Chain under the Belt and Road Initiatives: A System Dynamics Approach

Directory of Open Access Journals (Sweden)

Rui Zhao

2018-03-01

Full Text Available This study redesigns the supply chain of agricultural products in southwest China under the Belt and Road Initiative to improve its eco-efficiency by considering the associated agro-wastes flowing into bioenergy enterprise for energy production. Two scenarios are created, in which the first assumes that all waste flows into the enterprise, whereas the second only considers the inflow of agro-waste produced by farmers and the wholesale market. A system dynamics simulation is conducted by using carbon emissions per product as an indicator to obtain the optimal scenario for managerial practice and design an incentivizing mechanism to drive supply chain operations. A case study is provided to demonstrate application of the system dynamics. Finally, the limitations of the study are discussed to lay the foundation for further improvement.

Substation Reactive Power Regulation Strategy

Science.gov (United States)

Zhang, Junfeng; Zhang, Chunwang; Ma, Daqing

2018-01-01

With the increasing requirements on the power supply quality and reliability of distribution network, voltage and reactive power regulation of substations has become one of the indispensable ways to ensure voltage quality and reactive power balance and to improve the economy and reliability of distribution network. Therefore, it is a general concern of the current power workers and operators that what kind of flexible and effective control method should be used to adjust the on-load tap-changer (OLTC) transformer and shunt compensation capacitor in a substation to achieve reactive power balance in situ, improve voltage pass rate, increase power factor and reduce active power loss. In this paper, based on the traditional nine-zone diagram and combining with the characteristics of substation, a fuzzy variable-center nine-zone diagram control method is proposed and used to make a comprehensive regulation of substation voltage and reactive power. Through the calculation and simulation of the example, this method is proved to have satisfactorily reconciled the contradiction between reactive power and voltage in real-time control and achieved the basic goal of real-time control of the substation, providing a reference value to the practical application of the substation real-time control method.

Ethanol Distribution, Dispensing, and Use: Analysis of a Portion of the Biomass-to-Biofuels Supply Chain Using System Dynamics

Science.gov (United States)

Vimmerstedt, Laura J.; Bush, Brian; Peterson, Steve

2012-01-01

The Energy Independence and Security Act of 2007 targets use of 36 billion gallons of biofuels per year by 2022. Achieving this may require substantial changes to current transportation fuel systems for distribution, dispensing, and use in vehicles. The U.S. Department of Energy and the National Renewable Energy Laboratory designed a system dynamics approach to help focus government action by determining what supply chain changes would have the greatest potential to accelerate biofuels deployment. The National Renewable Energy Laboratory developed the Biomass Scenario Model, a system dynamics model which represents the primary system effects and dependencies in the biomass-to-biofuels supply chain. The model provides a framework for developing scenarios and conducting biofuels policy analysis. This paper focuses on the downstream portion of the supply chain–represented in the distribution logistics, dispensing station, and fuel utilization, and vehicle modules of the Biomass Scenario Model. This model initially focused on ethanol, but has since been expanded to include other biofuels. Some portions of this system are represented dynamically with major interactions and feedbacks, especially those related to a dispensing station owner’s decision whether to offer ethanol fuel and a consumer’s choice whether to purchase that fuel. Other portions of the system are modeled with little or no dynamics; the vehicle choices of consumers are represented as discrete scenarios. This paper explores conditions needed to sustain an ethanol fuel market and identifies implications of these findings for program and policy goals. A large, economically sustainable ethanol fuel market (or other biofuel market) requires low end-user fuel price relative to gasoline and sufficient producer payment, which are difficult to achieve simultaneously. Other requirements (different for ethanol vs. other biofuel markets) include the need for infrastructure for distribution and dispensing and

Ethanol distribution, dispensing, and use: analysis of a portion of the biomass-to-biofuels supply chain using system dynamics.

Science.gov (United States)

Vimmerstedt, Laura J; Bush, Brian; Peterson, Steve

2012-01-01

The Energy Independence and Security Act of 2007 targets use of 36 billion gallons of biofuels per year by 2022. Achieving this may require substantial changes to current transportation fuel systems for distribution, dispensing, and use in vehicles. The U.S. Department of Energy and the National Renewable Energy Laboratory designed a system dynamics approach to help focus government action by determining what supply chain changes would have the greatest potential to accelerate biofuels deployment. The National Renewable Energy Laboratory developed the Biomass Scenario Model, a system dynamics model which represents the primary system effects and dependencies in the biomass-to-biofuels supply chain. The model provides a framework for developing scenarios and conducting biofuels policy analysis. This paper focuses on the downstream portion of the supply chain-represented in the distribution logistics, dispensing station, and fuel utilization, and vehicle modules of the Biomass Scenario Model. This model initially focused on ethanol, but has since been expanded to include other biofuels. Some portions of this system are represented dynamically with major interactions and feedbacks, especially those related to a dispensing station owner's decision whether to offer ethanol fuel and a consumer's choice whether to purchase that fuel. Other portions of the system are modeled with little or no dynamics; the vehicle choices of consumers are represented as discrete scenarios. This paper explores conditions needed to sustain an ethanol fuel market and identifies implications of these findings for program and policy goals. A large, economically sustainable ethanol fuel market (or other biofuel market) requires low end-user fuel price relative to gasoline and sufficient producer payment, which are difficult to achieve simultaneously. Other requirements (different for ethanol vs. other biofuel markets) include the need for infrastructure for distribution and dispensing and

Twelve Theses on Reactive Rules for the Web

OpenAIRE

Bry, François; Eckert, Michael; Patranjan, Paula-Lavinia

2006-01-01

Reactivity, the ability to detect events and respond to them automatically through reactive programs, is a key requirement in many present-day information systems. Work on Web Services re ects the need for support of reactivity on a higher abstraction level than just message exchange by HTTP. This article presents the composite event query facilities of the reactive rule-based programming language XChange. Composite events are important in the dynamic world of the Web whe...

The role of uncertainty in supply chains under dynamic modeling

Directory of Open Access Journals (Sweden)

M. Fera

2017-01-01

Full Text Available The uncertainty in the supply chains (SCs for manufacturing and services firms is going to be, over the coming decades, more important for the companies that are called to compete in a new globalized economy. Risky situations for manufacturing are considered in trying to individuate the optimal positioning of the order penetration point (OPP. It aims at defining the best level of information of the client’s order going back through the several supply chain (SC phases, i.e. engineering, procurement, production and distribution. This work aims at defining a system dynamics model to assess competitiveness coming from the positioning of the order in different SC locations. A Taguchi analysis has been implemented to create a decision map for identifying possible strategic decisions under different scenarios and with alternatives for order location in the SC levels. Centralized and decentralized strategies for SC integration are discussed. In the model proposed, the location of OPP is influenced by the demand variation, production time, stock-outs and stock amount. Results of this research are as follows: (i customer-oriented strategies are preferable under high volatility of demand, (ii production-focused strategies are suggested when the probability of stock-outs is high, (iii no specific location is preferable if a centralized control architecture is implemented, (iv centralization requires cooperation among partners to achieve the SC optimum point, (v the producer must not prefer the OPP location at the Retailer level when the general strategy is focused on a decentralized approach.

Linking somatic and symbolic representation in semantic memory: the dynamic multilevel reactivation framework.

Science.gov (United States)

Reilly, Jamie; Peelle, Jonathan E; Garcia, Amanda; Crutch, Sebastian J

2016-08-01

Biological plausibility is an essential constraint for any viable model of semantic memory. Yet, we have only the most rudimentary understanding of how the human brain conducts abstract symbolic transformations that underlie word and object meaning. Neuroscience has evolved a sophisticated arsenal of techniques for elucidating the architecture of conceptual representation. Nevertheless, theoretical convergence remains elusive. Here we describe several contrastive approaches to the organization of semantic knowledge, and in turn we offer our own perspective on two recurring questions in semantic memory research: (1) to what extent are conceptual representations mediated by sensorimotor knowledge (i.e., to what degree is semantic memory embodied)? (2) How might an embodied semantic system represent abstract concepts such as modularity, symbol, or proposition? To address these questions, we review the merits of sensorimotor (i.e., embodied) and amodal (i.e., disembodied) semantic theories and address the neurobiological constraints underlying each. We conclude that the shortcomings of both perspectives in their extreme forms necessitate a hybrid middle ground. We accordingly propose the Dynamic Multilevel Reactivation Framework-an integrative model predicated upon flexible interplay between sensorimotor and amodal symbolic representations mediated by multiple cortical hubs. We discuss applications of the dynamic multilevel reactivation framework to abstract and concrete concept representation and describe how a multidimensional conceptual topography based on emotion, sensation, and magnitude can successfully frame a semantic space containing meanings for both abstract and concrete words. The consideration of 'abstract conceptual features' does not diminish the role of logical and/or executive processing in activating, manipulating and using information stored in conceptual representations. Rather, it proposes that the materials upon which these processes operate

Reducing stock-outs of essential tuberculosis medicines: a system dynamics modelling approach to supply chain management.

Science.gov (United States)

Bam, L; McLaren, Z M; Coetzee, E; von Leipzig, K H

2017-10-01

The under-performance of supply chains presents a significant hindrance to disease control in developing countries. Stock-outs of essential medicines lead to treatment interruption which can force changes in patient drug regimens, drive drug resistance and increase mortality. This study is one of few to quantitatively evaluate the effectiveness of supply chain policies in reducing shortages and costs. This study develops a systems dynamics simulation model of the downstream supply chain for amikacin, a second-line tuberculosis drug using 10 years of South African data. We evaluate current supply chain performance in terms of reliability, responsiveness and agility, following the widely-used Supply Chain Operation Reference framework. We simulate 141 scenarios that represent different combinations of supplier characteristics, inventory management strategies and demand forecasting methods to identify the Pareto optimal set of management policies that jointly minimize the number of shortages and total cost. Despite long supplier lead times and unpredictable demand, the amikacin supply chain is 98% reliable and agile enough to accommodate a 20% increase in demand without a shortage. However, this is accomplished by overstocking amikacin by 167%, which incurs high holding costs. The responsiveness of suppliers is low: only 57% of orders are delivered to the central provincial drug depot within one month. We identify three Pareto optimal safety stock management policies. Short supplier lead time can produce Pareto optimal outcomes even in the absence of other optimal policies. This study produces concrete, actionable guidelines to cost-effectively reduce stock-outs by implementing optimal supply chain policies. Preferentially selecting drug suppliers with short lead times accommodates unexpected changes in demand. Optimal supply chain management should be an essential component of national policy to reduce the mortality rate. © The Author 2017. Published by Oxford

Prediction of the Chapman-Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics.

Science.gov (United States)

Guo, Dezhou; Zybin, Sergey V; An, Qi; Goddard, William A; Huang, Fenglei

2016-01-21

The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman-Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ state parameters, providing the means to predict the performance of new materials prior to synthesis and characterization, allowing the simulation based design to be done in silico. Our Rx2CJ method is based on atomistic reactive molecular dynamics (RMD) using the QM-derived ReaxFF force field. We validate this method here by predicting the CJ point and detonation products for three typical energetic materials. We find good agreement between the predicted and experimental detonation velocities, indicating that this method can reliably predict the CJ state using modest levels of computation.

Complex dynamics of a MC-MS pricing model for a risk-averse supply chain with after-sale investment

Science.gov (United States)

Ma, Junhai; Sun, Lijian

2015-09-01

In this paper, we investigate the pricing strategy of the manufacturers and that of a common retailer, including their after-sale investment in a risk-averse supply chain. As the demand is not always for sure, the supply chain follows Manufacturers Cooperating (MC) and Manufacturers Stackelberg (MS). The main objective of the paper is to investigate the influence of the decision parameters such as the after-sale investment, wholesale price adjustment speed and risk preference on the stability and utilities of the risk-averse supply chain. The dynamic phenomena, such as the bifurcation, chaos and sensitivity to initial values are analyzed with 2D-bifurcation diagrams, double largest Lyapunov exponent and basins of attraction. The study shows that the faster the adjustment speed is, the more profits the retailer can make, but on the other hand, it is no good to manufacturers. Risk tolerance levels (RM and RR) affect the utility of the manufacturers and that of the retailer differently. A feedback control method is used to control the chaos in the supply chain.

Power supply and stabilization of the supply system on board using decentralized voltage rectifiers

Energy Technology Data Exchange (ETDEWEB)

Grueb, W; Wegerer, K

1987-04-01

The functionally redundant power supply system of the Transrapid 06 II maglev train is described; it comprises four independent, battery-buffered networks and 30 linear generators per train section. Voltage rectifiers adapt the velocity- and load-dependent linear generator voltage to the 440 V d.c. networks and assure dynamic stabilisation as well as buffer battery loading. The result is a high-reliability power supply system on board with optimum utilisation of the power supplied by the linear generators while the train is running.

Reactive molecular dynamic simulations on the gas separation performance of porous graphene membrane.

Science.gov (United States)

Esfandiarpoor, Somaye; Fazli, Mostafa; Ganji, Masoud Darvish

2017-11-29

The separation of gases molecules with similar diameter and shape is an important area of research. For example, the major challenge to set up sweeping carbon dioxide capture and storage (CCS) in power plants is the energy requisite to separate the CO 2 from flue gas. Porous graphene has been proposed as superior material for highly selective membranes for gas separation. Here we design some models of porous graphene with different sizes and shape as well as employ double layers porous graphene for efficient CO 2 /H 2 separation. The selectivity and permeability of gas molecules through various nanopores were investigated by using the reactive molecular dynamics simulation which considers the bond forming/breaking mechanism for all atoms. Furthermore, it uses a geometry-dependent charge calculation scheme that accounts appropriately for polarization effect which can play an important role in interacting systems. It was found that H-modified porous graphene membrane with pore diameter (short side) of about 3.75 Å has excellent selectivity for CO 2 /H 2 separation. The mechanism of gas penetration through the sub-nanometer pore was presented for the first time. The accuracy of MD simulation results validated by valuable DFT method. The present findings show that reactive MD simulation can propose an economical means of separating gases mixture.

A dynamic balance between magma supply and eruption rate at Kilauea volcano, Hawaii

Science.gov (United States)

Denlinger, R.P.

1997-01-01

The dynamic balance between magma supply and vent output at Kilauea volcano is used to estimate both the volume of magma stored within Kilauea volcano and its magma supply rate. Throughout most of 1991 a linear decline in volume flux from the Kupaianaha vent on Kilauea's east rift zone was associated with a parabolic variation in the elevation of Kilauea's summit as vent output initially exceeded then lagged behind the magma supply to the volcano. The correspondence between summit elevation and tilt established with over 30 years of data provided daily estimates of summit elevation in terms of summit tilt. The minimum in the parabolic variation in summit tilt and elevation (or zero elevation change) occurs when the magma supply to the reservoir from below the volcano equals the magma output from the reservoir to the surface, so that the magma supply rate is given by vent flux on that day. The measurements of vent flux and tilt establish that the magma supply rate to Kilauea volcano on June 19, 1991, was 217,000 ?? 10,000 m3/d (or 0.079 ?? 0.004 km3/yr). This is close to the average eruptive rate of 0.08 km3/yr between 1958 and 1984. In addition, the predictable response of summit elevation and tilt to each east rift zone eruption near Puu Oo since 1983 shows that summit deformation is also a measure of magma reservoir pressure. Given this, the correlation between the elevation of the Puu Oo lava lake (4 km uprift of Kupaianaha and 18 km from the summit) and summit tilt provides an estimate for magma pressure changes corresponding to summit tilt changes. The ratio of the change in volume to the change in reservoir pressure (dV/dP) during vent activity may be determined by dividing the ratio of volume erupted to change in summit tilt (dV/dtilt) by the ratio of pressure change to change in summit tilt (dP/dtilt). This measure of dV/dP, when combined with laboratory measurements of the bulk modulus of tholeitic melt, provides an estimate of 240 ?? 50 km3 for the volume

Impact of reactive settler models on simulated WWTP performance

DEFF Research Database (Denmark)

Gernaey, Krist; Jeppsson, Ulf; Batstone, Damien J.

2006-01-01

for an ASM1 case study. Simulations with a whole plant model including the non-reactive Takacs settler model are used as a reference, and are compared to simulation results considering two reactive settler models. The first is a return sludge model block removing oxygen and a user-defined fraction of nitrate......, combined with a non-reactive Takacs settler. The second is a fully reactive ASM1 Takacs settler model. Simulations with the ASM1 reactive settler model predicted a 15.3% and 7.4% improvement of the simulated N removal performance, for constant (steady-state) and dynamic influent conditions respectively....... The oxygen/nitrate return sludge model block predicts a 10% improvement of N removal performance under dynamic conditions, and might be the better modelling option for ASM1 plants: it is computationally more efficient and it will not overrate the importance of decay processes in the settler....

USING A NEW SUPPLY CHAIN PLANNING METHODOLOGY TO IMPROVE SUPPLY CHAIN EFFICIENCY

Directory of Open Access Journals (Sweden)

A.L.V. Raubenheimer

2012-01-01

Full Text Available

ENGLISH ABSTRACT: Effective supply chain planning and management has emerged as one of the most challenging opportunities for companies in the global economy during the last decade or two. This article reviews the evolution of Supply Chain Management and the traditional Supply Chain Solutions. It then introduces a new Supply Chain Planning methodology in which simulation modelling plays an important value-adding role to help organisations understand the dynamics of their Supply Chains.

AFRIKAANSE OPSOMMING:Effektiewe voorsieningskettingbeplanning en –bestuur het gedurende die laaste twee dekades ontwikkel tot een van die mees uitdagende geleenthede vir ondernemings in die wêreldekonomie. Hierdie artikel hersien kortliks die ontwikkeling van voorsieningskettingbestuur en die tradisionele oplossings. ‘n Nuwe voorsieningskettingbeplanningsmetodologie word dan voorgestel en bespreek waarin simulasiemodellering ‘n belangrike rol speel om ondernemings te help om die dinamika van hul voorsieningskettings te begryp.

Nuclear fuel supply: challenges and opportunities

International Nuclear Information System (INIS)

Lowen, S.

2006-01-01

Prices of uranium, conversion services and enrichment services have all significantly increased in the last few years. These price increases have generally been driven by a tightening in the supply of these products and services, mostly due to long lead times required to bring these products and services to the market. This paper will describe the various steps in the nuclear fuel cycle for natural and enriched uranium fuel, will discuss the development of the front-end fuel cycle for low void reactivity fuel, and will address the challenges faced in the long-term supply of each component, particularly in the light of potential demand increases as a result of a nuclear renaissance. The opportunities for new capacity and uranium production will be outlined and the process required to achieve sufficient new supply will be discussed. (author)

Approximate dynamic fault tree calculations for modelling water supply risks

International Nuclear Information System (INIS)

Lindhe, Andreas; Norberg, Tommy; Rosén, Lars

2012-01-01

Traditional fault tree analysis is not always sufficient when analysing complex systems. To overcome the limitations dynamic fault tree (DFT) analysis is suggested in the literature as well as different approaches for how to solve DFTs. For added value in fault tree analysis, approximate DFT calculations based on a Markovian approach are presented and evaluated here. The approximate DFT calculations are performed using standard Monte Carlo simulations and do not require simulations of the full Markov models, which simplifies model building and in particular calculations. It is shown how to extend the calculations of the traditional OR- and AND-gates, so that information is available on the failure probability, the failure rate and the mean downtime at all levels in the fault tree. Two additional logic gates are presented that make it possible to model a system's ability to compensate for failures. This work was initiated to enable correct analyses of water supply risks. Drinking water systems are typically complex with an inherent ability to compensate for failures that is not easily modelled using traditional logic gates. The approximate DFT calculations are compared to results from simulations of the corresponding Markov models for three water supply examples. For the traditional OR- and AND-gates, and one gate modelling compensation, the errors in the results are small. For the other gate modelling compensation, the error increases with the number of compensating components. The errors are, however, in most cases acceptable with respect to uncertainties in input data. The approximate DFT calculations improve the capabilities of fault tree analysis of drinking water systems since they provide additional and important information and are simple and practically applicable.

Impact of seasonal forcing on reactive ecological systems.

Science.gov (United States)

Vesipa, Riccardo; Ridolfi, Luca

2017-04-21

Our focus is on the short-term dynamics of reactive ecological systems which are stable in the long term. In these systems, perturbations can exhibit significant transient amplifications before asymptotically decaying. This peculiar behavior has attracted increasing attention. However, reactive systems have so far been investigated assuming that external environmental characteristics remain constant, although environmental conditions (e.g., temperature, moisture, water availability, etc.) can undergo substantial changes due to seasonal cycles. In order to fill this gap, we propose applying the adjoint non-modal analysis to study the impact of seasonal variations of environmental conditions on reactive systems. This tool allows the transient dynamics of a perturbation affecting non-autonomous ecological systems to be described. To show the potential of this approach, a seasonally forced prey-predator model with a Holling II type functional response is studied as an exemplifying case. We demonstrate that seasonalities can greatly affect the transient dynamics of the system. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Coordination of calculation and experimental procedures in the determination of high-negative reactivities

International Nuclear Information System (INIS)

Pinegin, A.A.; Tsyganov, S.V.

1999-01-01

Usually three sources of information about the value of inserted negative reactivity (ρ) are used: dynamical experiment with reactimeters, solution of conventionally critical problems, and dynamical calculation of the process of reactivity insertion with the reactimer model. Each of them gives they own estimation of ρ. The discrepancy between these estimation could be significant, particularly noticeable in dissymmetric insertion of perturbation. The paper discusses origin of problems of estimation high negative reactivity with reactivity meter. Authors believe that correct method of high negative reactivity estimation have to include three dimensional dynamic core model for taking to account spatial effect. Moreover, some special process, such a removal of delayed neutron emitters, change in the fraction of delayed neutrons, inner source etc. (Authors)

Reactive Power Management in Electric Power Systems

African Journals Online (AJOL)

(Ferranti effect) would limit the power transfer and the transmission range in the absence of any compensation measures. Journal of EAEA, Vol 14, 1997. In this paper, the management of the reactive power is explored with the aim of improving the quality and the reliability of the supply in the EELPA's interconnected system ...

Study and Simulation on Dynamics of a Risk-Averse Supply Chain Pricing Model with Dual-Channel and Incomplete Information

Science.gov (United States)

Sun, Lijian; Ma, Junhai

Under the industrial background of dual-channel, volatility in demand of consumers, we use the theory of bifurcations and numerical simulation tools to investigate the dynamic pricing game in a dual-channel supply chain with risk-averse behavior and incomplete information. Due to volatility of demand of consumers, we consider all the players in the supply chain are risk-averse. We assume there exist Bertrand game and Manufacturers’ Stackelberg in the chain which are closer to reality. The main objective of the paper is to investigate the complex influence of the decision parameters such as wholesale price adjustment speed, risk preference and service value on stability of the risk-averse supply chain and average utilities of all the players. We lay emphasis on the influence of chaos on average utilities of all the players which did not appear in previous studies. The dynamic phenomena, such as the bifurcation, chaos and sensitivity to initial values are analyzed by 2D bifurcation phase portraits, Double Largest Lyapunov exponent, basins of attraction and so on. The study shows that the manufacturers should slow down their wholesale price adjustment speed to get more utilities, if the manufacturers are willing to take on more risk, they will get more profits, but they must keep their wholesale prices in a certain range in order to maintain the market stability.

Natural gas supply and demand in Italy

International Nuclear Information System (INIS)

Comaschi, C.; Di Giulio, E.; Sormani, E.

2007-01-01

This article explores the dynamics between natural gas supply and demand in Italy. In order to supply Italy with increasing volumes of gas, several new pipelines and re gasification plants are expected in the next future, but their implementation is uncertain. Thus, there exist the possibility of natural gas shortage in the future. On the other hand, if all the expected projects will be implemented, situations of oversupply cannot be excluded. A system dynamics model deepens such as issue [it

Sourcing and pricing strategies for two retailers in a decentralized supply chain system under supply disruption

Directory of Open Access Journals (Sweden)

M.A. Azarmehr

2012-01-01

Full Text Available This paper presents the decentralized supply chain with two suppliers and two competing retailers. It also investigates the sourcing and pricing strategies of two retailers in a decentralized supply chain system under a supply disruption environment. These retailers face their individual stochastic demand markets; however, they compete with each other through a two-stage price and service operation. The interactive dynamics among retailers is characterized, including the existence and uniqueness of the Nash Equilibrium in service and price games demonstrated.

Long-term reactive transport modelling of stabilized/solidified waste: from dynamic leaching tests to disposal scenarios

Energy Technology Data Exchange (ETDEWEB)

Windt, Laurent de [Ecole des Mines de Paris, CG-Hydrodynamics and Reaction Group, 35 R. St-Honore, 77300 Fontainebleau (France)]. E-mail: laurent.dewindt@ensmp.fr; Badreddine, Rabia [INERIS, Direction des Risques Chroniques, Unite Dechets et Sites Pollues, Parc Technologique Alata BP 2, 60550 Verneuil-en-Halatte (France); Lagneau, Vincent [Ecole des Mines de Paris, CG-Hydrodynamics and Reaction Group, 35 R. St-Honore, 77300 Fontainebleau (France)

2007-01-31

Environmental impact assessment of hazardous waste disposal relies, among others, on standardized leaching tests characterized by a strong coupling between diffusion and chemical processes. In that respect, this study shows that reactive transport modelling is a useful tool to extrapolate laboratory results to site conditions characterized by lower solution/solid (L/S) ratios, site specific geometry, infiltration, etc. A cement solidified/stabilized (S/S) waste containing lead is investigated as a typical example. The reactive transport model developed in a previous study to simulate the initial state of the waste as well as laboratory batch and dynamic tests is first summarized. Using the same numerical code (HYTEC), this model is then integrated to a simplified waste disposal scenario assuming a defective cover and rain water infiltration. The coupled evolution of the S/S waste chemistry and the pollutant plume migration are modelled assessing the importance of the cracking state of the monolithic waste. The studied configurations correspond to an undamaged and fully sealed system, a few main fractures between undamaged monoliths and, finally, a dense crack-network in the monoliths. The model considers the potential effects of cracking, first the increase of rain water and carbon dioxide infiltration and, secondly, the increase of L/S ratio and reactive surfaces, using either explicit fracture representation or dual porosity approaches.

The Effect of Aging on the Dynamics of Reactive and Proactive Cognitive Control of Response Interference.

Science.gov (United States)

Xiang, Ling; Zhang, Baoqiang; Wang, Baoxi; Jiang, Jun; Zhang, Fenghua; Hu, Zhujing

2016-01-01

A prime-target interference task was used to investigate the effects of cognitive aging on reactive and proactive control after eliminating frequency confounds and feature repetitions from the cognitive control measures. We used distributional analyses to explore the dynamics of the two control functions by distinguishing the strength of incorrect response capture and the efficiency of suppression control. For reactive control, within-trial conflict control and between-trial conflict adaption were analyzed. The statistical analysis showed that there were no reliable between-trial conflict adaption effects for either young or older adults. For within-trial conflict control, the results revealed that older adults showed larger interference effects on mean RT and mean accuracy. Distributional analyses showed that the decline mainly stemmed from inefficient suppression rather than from stronger incorrect responses. For proactive control, older adults showed comparable proactive conflict resolution to young adults on mean RT and mean accuracy. Distributional analyses showed that older adults were as effective as younger adults in adjusting their responses based on congruency proportion information to minimize automatic response capture and actively suppress the direct response activation. The results suggest that older adults were less proficient at suppressing interference after conflict was detected but can anticipate and prevent inference in response to congruency proportion manipulation. These results challenge earlier views that older adults have selective deficits in proactive control but intact reactive control.

Spectroscopic analysis of 8-hydroxyquinoline-5-sulphonic acid and investigation of its reactive properties by DFT and molecular dynamics simulations

Science.gov (United States)

Sureshkumar, B.; Sheena Mary, Y.; Panicker, C. Yohannan; Resmi, K. S.; Suma, S.; Armaković, Stevan; Armaković, Sanja J.; Van Alsenoy, C.

2017-12-01

A detailed interpretation of the FT-IR and FT-Raman spectra has been performed on the basis of the observed and calculated infrared and Raman spectra as well as calculated potential energy distribution values. Comparison of Raman and SERS spectra suggests a tilted orientation of the rings on the metal surface. The dipole moment, polarizability and first and second order hyperpolarizability values of the molecule were calculated. Global reactivity parameters were predicted. The relative reactivities towards electrophilic and nucleophilic attack are predicted using molecular electrostatic potential map. Average local ionization energy (ALIE) and Fukui functions have been inspected in order to investigate local reactivity properties of title molecule. The importance of autoxidation and hydrolysis mechanisms for the title molecule has been assessed by DFT calculations of bond dissociation energies (BDE) and by calculations of radial distribution functions (RDFs) after molecular dynamics (MD) simulations. Molecular docking studies suggest that the title compound can be a lead compound for developing new anti-cancerous drug.

Haber Process Made Efficient by Hydroxylated Graphene: Ab Initio Thermochemistry and Reactive Molecular Dynamics.

Science.gov (United States)

Chaban, Vitaly V; Prezhdo, Oleg V

2016-07-07

The Haber-Bosch process is the main industrial method for producing ammonia from diatomic nitrogen and hydrogen. We use a combination of ab initio thermochemical analysis and reactive molecular dynamics to demonstrate that a significant increase in the ammonia production yield can be achieved using hydroxylated graphene and related species. Exploiting the polarity difference between N2/H2 and NH3, as well as the universal proton acceptor behavior of NH3, we demonstrate a strong shift of the equilibrium of the Haber-Bosch process toward ammonia (ca. 50 kJ mol(-1) enthalpy gain and ca. 60-70 kJ mol(-1) free energy gain). The modified process is of significant importance to the chemical industry.

Combining a reactive potential with a harmonic approximation for molecular dynamics simulation of failure: construction of a reduced potential

Science.gov (United States)

Tejada, I. G.; Brochard, L.; Stoltz, G.; Legoll, F.; Lelièvre, T.; Cancès, E.

2015-01-01

Molecular dynamics is a simulation technique that can be used to study failure in solids, provided the inter-atomic potential energy is able to account for the complex mechanisms at failure. Reactive potentials fitted on ab initio results or on experimental values have the ability to adapt to any complex atomic arrangement and, therefore, are suited to simulate failure. But the complexity of these potentials, together with the size of the systems considered, make simulations computationally expensive. In order to improve the efficiency of numerical simulations, simpler harmonic potentials can be used instead of complex reactive potentials in the regions where the system is close to its ground state and a harmonic approximation reasonably fits the actual reactive potential. However the validity and precision of such an approach has not been investigated in detail yet. We present here a methodology for constructing a reduced potential and combining it with the reactive one. We also report some important features of crack propagation that may be affected by the coupling of reactive and reduced potentials. As an illustrative case, we model a crystalline two-dimensional material (graphene) with a reactive empirical bond-order potential (REBO) or with harmonic potentials made of bond and angle springs that are designed to reproduce the second order approximation of REBO in the ground state. We analyze the consistency of this approximation by comparing the mechanical behavior and the phonon spectra of systems modeled with these potentials. These tests reveal when the anharmonicity effects appear. As anharmonic effects originate from strain, stress or temperature, the latter quantities are the basis for establishing coupling criteria for on the fly substitution in large simulations.

Exploring the impact of dynamic capabilities on sustainable supply chain firm's performance using Grey-Analytical Hierarchy Process

DEFF Research Database (Denmark)

Govindan, Kannan; Mathivathanan, Deepak; Haq, A. Noorul

2017-01-01

Dynamic capabilities (DCs) are the inherent capabilities developed by firms through the implementation of Sustainable Supply Chain practices. These DCs serve as a backbone for the firms to achieve competitive advantages in contemporary ever-changing markets. The present study focuses on exploring...... industrial managers to identify specific influential DCs for each performance measure category by overcoming the limitations of few experts through the application of the grey multi criteria decision making system. Identifying and prioritizing performance-specific DCs allow sustainable supply chain oriented...... performance measures identified from the literature. First, through a questionnaire survey with industrial experts from south India as respondents, the initial list of 77 DCs is confined to a list of 40 essential DCs. Second, the shortlisted 40 DCs are grouped under six performance measures; a logical...

Modelling and automatic reactive power control of isolated wind-diesel hybrid power systems using ANN

International Nuclear Information System (INIS)

Bansal, R.C.

2008-01-01

This paper presents an artificial neural network (ANN) based approach to tune the parameters of the static var compensator (SVC) reactive power controller over a wide range of typical load model parameters. The gains of PI (proportional integral) based SVC are optimised for typical values of the load voltage characteristics (n q ) by conventional techniques. Using the generated data, the method of multi-layer feed forward ANN with error back propagation training is employed to tune the parameters of the SVC. An ANN tuned SVC controller has been applied to control the reactive power of a variable slip/speed isolated wind-diesel hybrid power system. It is observed that the maximum deviations of all parameters are more for larger values of n q . It has been shown that initially synchronous generator supplies the reactive power required by the induction generator and/or load, and the latter reactive power is purely supplied by the SVC

Modelling and automatic reactive power control of isolated wind-diesel hybrid power systems using ANN

Energy Technology Data Exchange (ETDEWEB)

Bansal, R.C. [Electrical and Electronics Engineering Division, School of Engineering and Physics, The University of the South Pacific, Suva (Fiji)

2008-02-15

This paper presents an artificial neural network (ANN) based approach to tune the parameters of the static var compensator (SVC) reactive power controller over a wide range of typical load model parameters. The gains of PI (proportional integral) based SVC are optimised for typical values of the load voltage characteristics (n{sub q}) by conventional techniques. Using the generated data, the method of multi-layer feed forward ANN with error back propagation training is employed to tune the parameters of the SVC. An ANN tuned SVC controller has been applied to control the reactive power of a variable slip/speed isolated wind-diesel hybrid power system. It is observed that the maximum deviations of all parameters are more for larger values of n{sub q}. It has been shown that initially synchronous generator supplies the reactive power required by the induction generator and/or load, and the latter reactive power is purely supplied by the SVC. (author)

Sustainable supply chain design for waste cooking oil-based biodiesel in bogor using dynamic system approach

Science.gov (United States)

Syahdan, A. D.; Arkeman, Y.; Wijaya, H.

2017-05-01

Biodiesel is one of the alternative fuels that are environmentally friendly. Besides palm oil, biodiesel can also be produced from waste cooking oil. Since 2007, the government of Bogor has been utilizing waste cooking oil into biodiesel for use as Transpakuan bus’ fuel. However, in practice, the amount of waste cooking oil supplied is never sufficient the needs of fuel of 30 units Transpakuan bus. The main objective of this research is to analyze the availability of waste cooking oil that will be converted into biodiesel within the next ten years as well as providing policy advice to support the program. The method used is a dynamic system that is followed by simulation of multiple scenarios that have been defined. The system is divided into three subsystems, namely supply subsystem, demand subsystem, and production subsystem. The results showed that the current system is not able to guarantee the sustainability of the supply chain of waste cooking oil as a raw material of biodiesel. From some of the scenarios tested can be concluded that biodiesel needs would increase in line with the trend of the use of environmentally friendly fuels. It takes a new system and a new policy relating to the biodiesel supply chain. Policy suggestions that can be proposed from this research is to increase supplier participation, objectify the program of converting angkot into Transpakuan bus, and support the development of biodiesel industry.

Estimation of reactive power sources dynamic limits for Volt / VAr control

International Nuclear Information System (INIS)

Orozco Alvarado, Juan Jose

2013-01-01

A generic model of capacity curves is obtained from the theoretical capacity curves of the distribution generators and reactive compensation elements. The obtained generic model is structured in a simplified method of points, taking eight strategic points of two detailed curves of a generator and through a series of interpolations, achieving the estimation of limits of capacity of delivery / consumption of the generator. The theory of electric generation elements and reactive power compensation is reviewed. The curves of capacity 'Reactive Power / Active Power' are achieved for different values of tension: from wind generators with complete converter and doubly fed, photovoltaic generators with inverter and synchronous generators. The 'Reactive Power / Line Tension' capacity curves are acquired from static var compensators (SVC). The generic limits of generators and SVC are estimated from the capacity curves [es

Heavy oil supply economics and supply response to low oil prices

International Nuclear Information System (INIS)

Fisher, L.

1999-01-01

The dynamics of the heavy oil industry are examined, including prices, market demand, supply and supply costs. Price assumptions are provided for the reference case oil price (west Texas intermediate at Cushing). Supply cost methodology is explained. Capital and operating costs for various heavy oil and synthetic sources are derived from modeling results. The range of supply costs for heavy oil and bitumen from various sources, supply costs in terms of reference case market values and in terms of 1995-1996 average market values for Bow River crude, are derived. The CERI long term supply forecast model is explained. Western Canada upstream oil and gas cash flow and capital expenditures, eastern Canada exploration and expenditures by hydrocarbon type, and Canadian heavy oil and bitumen production based on reference case prices are estimated. Based on these projections the outlook for heavy oil at reference case prices for better than average quality resources is judged to be economic. Lower quality resources will require technology gains for successful commercialization. SAGD is a likely candidate in this respect. Again based on reference prices, production is forecast to decline by 100 Kb/d over the next five years. Diluent supply is considered to be adequate throughout the forecast period. As far as thermal bitumen is concerned, the growth could, in fact, exceed the projection, but if so, more upgrading will be required. 11 figs

Applying System Dynamics Approach to the Fast Fashion Supply Chain: Case Study of an SME in Indonesia

Directory of Open Access Journals (Sweden)

Mariany W Lidia

2012-09-01

Full Text Available The fashion industry is the biggest contributor among the 14 creative industries in Indonesia. Nowadays many apparel companies are shifting toward the vertical integration. Since speed is everything to be successful in the apparel industry, fast fashion retailers must quickly respond to the market demand. This papers aims to develop a model of the supply chain of a small and medium scale enterprise (SME of an apparel company in Indonesia and to propose a decision support system using System Dynamics (SD and helps the management to identify the best business strategy. Simulated scenarios can help the management to identify the most appropriate policy to be applied in the future. Case study method was used in this research where data were collected from a typical fast fashion firm in Indonesia that produces its own wares ranging from raw materials to be ready-to-wear clothes, has three stores, a warehouse and is running online sales system. We analyses the result of many simulations in a fashion company from an operational point of view and from them we derive suggestions about the future business strategy in a small and medium fashion company in Indonesia. Keywords: system dynamics, fast fashion, supply chain management, SME, Indonesia

A new power supply for superconductive magnetic energy storage system

International Nuclear Information System (INIS)

Karady, G.G.; Han, B.M.

1992-01-01

In this paper a new power supply for a superconductive magnetic energy storage system, which permits a fast independent regulation of the active and reactive power, is presented. The power supply is built with several units connected in parallel. Each unit consists of a 24-pulse bridge converter, thyristor-switched tap-changing transformer, and thyristor-switched capacitor bank. Its system operation is analyzed by computer simulation and a feasible system realization is shown. A superconductive magnetic energy storage system with the proposed power supply has the capability of leveling the load variation, damping the low-frequency oscillation, and improving the transient stability in the power system. This power supply can be built with commercially available components using well-proven technologies

Memory reactivation improves visual perception.

Science.gov (United States)

Amar-Halpert, Rotem; Laor-Maayany, Rony; Nemni, Shlomi; Rosenblatt, Jonathan D; Censor, Nitzan

2017-10-01

Human perception thresholds can improve through learning. Here we report findings challenging the fundamental 'practice makes perfect' basis of procedural learning theory, showing that brief reactivations of encoded visual memories are sufficient to improve perceptual discrimination thresholds. Learning was comparable to standard practice-induced learning and was not due to short training per se, nor to an epiphenomenon of primed retrieval enhancement. The results demonstrate that basic perceptual functions can be substantially improved by memory reactivation, supporting a new account of perceptual learning dynamics.

Reward disrupts reactivated human skill memory

OpenAIRE

Dayan, Eran; Laor-Maayany, Rony; Censor, Nitzan

2016-01-01

Accumulating evidence across species and memory domains shows that when an existing memory is reactivated, it becomes susceptible to modifications. However, the potential role of reward signals in these mechanisms underlying human memory dynamics is unknown. Leaning on a wealth of findings on the role of reward in reinforcing memory, we tested the impact of reinforcing a skill memory trace with monetary reward following memory reactivation, on strengthening of the memory trace. Reinforcing re...

The inter-relationships between urban dynamics and water resource and supply based on multitemporal analysis

Science.gov (United States)

Aldea, Alexandru; Aldea, Mihaela

2016-08-01

. In areas of rapid growth the worse problems came from the inadequate amount of potable water, the continuous deterioration of water quality and the slow progress in the water resources management and supply. The effects of urban dynamics over the water use and sustainability deserves an increasing study over the recent history in order to provide for an optimal management of the interrelationships between them.

Performance measurement for supply chain management and evaluation criteria determination for reverse supply chain management

Science.gov (United States)

Kongar, N. Elif

2004-12-01

Today, since customers are able to obtain similar-quality products for similar prices, the lead time has become the only preference criterion for most of the consumers. Therefore, it is crucial that the lead time, i.e., the time spent from the raw material phase till the manufactured good reaches the customer, is minimized. This issue can be investigated under the title of Supply Chain Management (SCM). An efficiently managed supply chain can lead to reduced response time for customers. To achieve this, continuous observation of supply chain efficiency, i.e., a constant performance evaluation of the current SCM is required. Widely used conventional performance measurement methods lack the ability to evaluate a SCM since the supply chain is a dynamic system that requires a more thorough and flexible performance measurement technique. Balanced Scorecard (BS) is an efficient tool for measuring the performance of dynamic systems and has a proven capability of providing the decision makers with the appropriate feedback data. In addition to SCM, a relatively new management field, namely reverse supply chain management (RSCM), also necessitates an appropriate evaluation approach. RSCM differs from SCM in many aspects, i.e., the criteria used for evaluation, the high level of uncertainty involved etc., not allowing the usage of identical evaluation techniques used for SCM. This study proposes a generic Balanced Scorecard to measure the performance of supply chain management while defining the appropriate performance measures for SCM. A scorecard prototype, ESCAPE, is presented to demonstrate the evaluation process.

State-to-state dynamics of the H*(n) + HD → D*(n′) + H2 reactive scattering

International Nuclear Information System (INIS)

Yu, Shengrui; Su, Shu; Dai, Dongxu; Yuan, Kaijun; Yang, Xueming

2014-01-01

The state-to-state dynamics of the H * (n) + HD → D * (n ′ ) + H 2 reactive scattering at the collision energy of 0.5 eV have been carried out for the first time by using H-atom Rydberg tagging time-of-flight technique. Experimental results show that the angular distribution of the total H 2 products presents clearly forward-backward asymmetric, which considerably differs from that of the corresponding H + + HD → D + + H 2 reaction predicted by previously theoretical calculations. Such disagreement between these two processes suggests that the Fermi independent-collider model is also not valid in describing the dynamics of isotopic variants of the H * + H 2 reaction. The rotational state distribution of the H 2 products demonstrates a saw-toothed distribution with odd-j ′ > even-j ′ . This interesting observation is strongly influenced by nuclear spin statistics

Generation of predictive price and trading volume patterns in a model of dynamically evolving free market supply and demand

Directory of Open Access Journals (Sweden)

J. K. Wang

2001-01-01

Full Text Available I present a model of stock market price fluctuations incorporating effects of share supply as a history-dependent function of previous purchases and share demand as a function of price deviation from moving averages. Price charts generated show intervals of oscillations switching amplitude and frequency suddenly in time, forming price and trading volume patterns well-known in market technical analysis. Ultimate price trends agree with traditional predictions for specific patterns. The consideration of dynamically evolving supply and demand in this model resolves the apparent contradiction with the Efficient Market Hypothesis: perceptions of imprecise equity values by a world of investors evolve over non-negligible periods of time, with dependence on price history.

The effect of aging on the dynamics of reactive and proactive cognitive control of response interference

Directory of Open Access Journals (Sweden)

Ling Xiang

2016-11-01

Full Text Available A prime-target interference task was used to investigate the effects of cognitive aging on reactive and proactive control in which frequency confounds and feature repetitions were eliminated from the cognitive control measures. We used distributional analyses to explore the dynamics of the two control functions by distinguishing the strength of incorrect response capture and the efficiency of suppression control. For reactive control, within-trial conflict control and between-trial conflict adaption were analyzed. The statistical analysis showed that there were no reliable between-trial conflict adaption effects for both young and older adults. For within-trial conflict control, the results revealed that older adults showed larger interference effects on mean RT and mean accuracy. Distributional analyses showed that the decline mainly stemmed from inefficient suppression rather than from stronger incorrect responses. For proactive control, older adults showed comparable proactive conflict resolution than young adults on mean RT and mean accuracy. Distributional analyses showed older adults were as effective as younger adults in adjusting their responses to minimize automatic response capture and actively suppress the direct response activation based on congruency proportion information. The results suggest that older adults were less proficient at suppressing interference after conflict was detected but can anticipate and prevent inference in response to congruency proportion manipulation. The results challenge earlier views that older adults have selective deficits in proactive control but are spared in reactive control.

Petroleum supply annual 1996: Volume 1

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-06-01

The Petroleum Supply Annual (PSA) contains information on the supply and disposition of crude oil and petroleum products. The publication reflects data that were collected from the petroleum industry during 1996 through annual and monthly surveys. The PSA is divided into two volumes. This first volume contains three sections: Summary Statistics, Detailed Statistics, and Refinery Capacity; each with final annual data. The summary statistics section show 16 years of data depicting the balance between supply, disposition and ending stocks for various commodities including crude oil, motor gasoline, distillate fuel oil, residual fuel oil, jet fuel propane/propylene, and liquefied petroleum gases. The detailed statistics section provide 1996 detailed statistics on supply and disposition, refinery operations, imports and exports, stocks, and transportation of crude oil and petroleum products. The refinery capacity contain listings of refineries and associated crude oil distillation and downstream capacities by State, as of January 1, 1997, as well as summaries of corporate refinery capacities and refinery storage capacities. In addition, refinery receipts of crude oil by method of transportation for 1996 are provided. Also included are fuels consumed at refineries, and lists of shutdowns, sales, reactivations, and mergers during 1995 and 1996. 16 figs., 59 tabs.

Petroleum supply annual 1996: Volume 1

International Nuclear Information System (INIS)

1997-06-01

The Petroleum Supply Annual (PSA) contains information on the supply and disposition of crude oil and petroleum products. The publication reflects data that were collected from the petroleum industry during 1996 through annual and monthly surveys. The PSA is divided into two volumes. This first volume contains three sections: Summary Statistics, Detailed Statistics, and Refinery Capacity; each with final annual data. The summary statistics section show 16 years of data depicting the balance between supply, disposition and ending stocks for various commodities including crude oil, motor gasoline, distillate fuel oil, residual fuel oil, jet fuel propane/propylene, and liquefied petroleum gases. The detailed statistics section provide 1996 detailed statistics on supply and disposition, refinery operations, imports and exports, stocks, and transportation of crude oil and petroleum products. The refinery capacity contain listings of refineries and associated crude oil distillation and downstream capacities by State, as of January 1, 1997, as well as summaries of corporate refinery capacities and refinery storage capacities. In addition, refinery receipts of crude oil by method of transportation for 1996 are provided. Also included are fuels consumed at refineries, and lists of shutdowns, sales, reactivations, and mergers during 1995 and 1996. 16 figs., 59 tabs

COMPARISON OF REACTIVITY OF SYNTHETIC AND BOVINE HYDROXYAPATITE IN VITRO UNDER DYNAMIC CONDITIONS

Directory of Open Access Journals (Sweden)

DIANA HORKAVCOVÁ

2014-03-01

Full Text Available Hydroxyapatite materials prepared by two methods: synthetic (HA–S and bovine (HA-B granules were exposed to a longterm in vitro test under dynamic conditions. Testing cells, filled up to one fourth (¼V of their volume with the tested material, were exposed to continuous flow of simulated body fluid (SBF for 56 days. The objective of the experiment was to determine whether reactivity of the biomaterials (hydroxyapatites, prepared by different methods but identical in terms of their chemical and phase composition, in SBF were comparable. Analyses of the solutions proved that both materials were highly reactive from the very beginning of interaction with SBF (significant decrease of Ca2+ and (PO43- concentrations in the leachate. SEM/EDS images have shown that the surface of bovine HA-B was covered with a new hydroxyapatite (HAp phase in the first two weeks of the test while synthetic HA–S was covered after two weeks of the immersion in SBF. At the end of the test, day 56, both materials were completely covered with well developed porous HAp phase in form of nano-plates. A calculation of the rate of HAp formation from the concentration of (PO43- ions in SBF leachates confirmed that all removed ions were consumed for the formation of the HAp phase throughout the entire testing time for bovine HA–B and only during the second half of the testing time for synthetic HA–S.

Towards an Empirical-Relational Model of Supply Chain Flexibility

OpenAIRE

Santanu Mandal

2015-01-01

Supply chains are prone to disruptions and associated risks. To develop capabilities for risk mitigation, supply chains need to be flexible. A flexible supply chain can respond better to environmental contingencies. Based on the theoretical tenets of resource-based view, relational view and dynamic capabilities theory, the current study develops a relational model of supply chain flexibility comprising trust, commitment, communication, co-operation, adaptation and interdependence. Subsequentl...

Reward disrupts reactivated human skill memory.

Science.gov (United States)

Dayan, Eran; Laor-Maayany, Rony; Censor, Nitzan

2016-06-16

Accumulating evidence across species and memory domains shows that when an existing memory is reactivated, it becomes susceptible to modifications. However, the potential role of reward signals in these mechanisms underlying human memory dynamics is unknown. Leaning on a wealth of findings on the role of reward in reinforcing memory, we tested the impact of reinforcing a skill memory trace with monetary reward following memory reactivation, on strengthening of the memory trace. Reinforcing reactivated memories did not strengthen the memory, but rather led to disruption of the memory trace, breaking down the link between memory reactivation and subsequent memory strength. Statistical modeling further revealed a strong mediating role for memory reactivation in linking between memory encoding and subsequent memory strength only when the memory was replayed without reinforcement. We suggest that, rather than reinforcing the existing memory trace, reward creates a competing memory trace, impairing expression of the original reward-free memory. This mechanism sheds light on the processes underlying skill acquisition, having wide translational implications.

Supply based on demand dynamical model

Science.gov (United States)

Levi, Asaf; Sabuco, Juan; Sanjuán, Miguel A. F.

2018-04-01

We propose and numerically analyze a simple dynamical model that describes the firm behaviors under uncertainty of demand. Iterating this simple model and varying some parameter values, we observe a wide variety of market dynamics such as equilibria, periodic, and chaotic behaviors. Interestingly, the model is also able to reproduce market collapses.

Proactive Supply Chain Performance Management with Predictive Analytics

Directory of Open Access Journals (Sweden)

Nenad Stefanovic

2014-01-01

Full Text Available Today’s business climate requires supply chains to be proactive rather than reactive, which demands a new approach that incorporates data mining predictive analytics. This paper introduces a predictive supply chain performance management model which combines process modelling, performance measurement, data mining models, and web portal technologies into a unique model. It presents the supply chain modelling approach based on the specialized metamodel which allows modelling of any supply chain configuration and at different level of details. The paper also presents the supply chain semantic business intelligence (BI model which encapsulates data sources and business rules and includes the data warehouse model with specific supply chain dimensions, measures, and KPIs (key performance indicators. Next, the paper describes two generic approaches for designing the KPI predictive data mining models based on the BI semantic model. KPI predictive models were trained and tested with a real-world data set. Finally, a specialized analytical web portal which offers collaborative performance monitoring and decision making is presented. The results show that these models give very accurate KPI projections and provide valuable insights into newly emerging trends, opportunities, and problems. This should lead to more intelligent, predictive, and responsive supply chains capable of adapting to future business environment.

Proactive supply chain performance management with predictive analytics.

Science.gov (United States)

Stefanovic, Nenad

2014-01-01

Today's business climate requires supply chains to be proactive rather than reactive, which demands a new approach that incorporates data mining predictive analytics. This paper introduces a predictive supply chain performance management model which combines process modelling, performance measurement, data mining models, and web portal technologies into a unique model. It presents the supply chain modelling approach based on the specialized metamodel which allows modelling of any supply chain configuration and at different level of details. The paper also presents the supply chain semantic business intelligence (BI) model which encapsulates data sources and business rules and includes the data warehouse model with specific supply chain dimensions, measures, and KPIs (key performance indicators). Next, the paper describes two generic approaches for designing the KPI predictive data mining models based on the BI semantic model. KPI predictive models were trained and tested with a real-world data set. Finally, a specialized analytical web portal which offers collaborative performance monitoring and decision making is presented. The results show that these models give very accurate KPI projections and provide valuable insights into newly emerging trends, opportunities, and problems. This should lead to more intelligent, predictive, and responsive supply chains capable of adapting to future business environment.

Proactive Supply Chain Performance Management with Predictive Analytics

Science.gov (United States)

Stefanovic, Nenad

2014-01-01

Today's business climate requires supply chains to be proactive rather than reactive, which demands a new approach that incorporates data mining predictive analytics. This paper introduces a predictive supply chain performance management model which combines process modelling, performance measurement, data mining models, and web portal technologies into a unique model. It presents the supply chain modelling approach based on the specialized metamodel which allows modelling of any supply chain configuration and at different level of details. The paper also presents the supply chain semantic business intelligence (BI) model which encapsulates data sources and business rules and includes the data warehouse model with specific supply chain dimensions, measures, and KPIs (key performance indicators). Next, the paper describes two generic approaches for designing the KPI predictive data mining models based on the BI semantic model. KPI predictive models were trained and tested with a real-world data set. Finally, a specialized analytical web portal which offers collaborative performance monitoring and decision making is presented. The results show that these models give very accurate KPI projections and provide valuable insights into newly emerging trends, opportunities, and problems. This should lead to more intelligent, predictive, and responsive supply chains capable of adapting to future business environment. PMID:25386605

Improving Power Quality in AC Supply Grids

Directory of Open Access Journals (Sweden)

Piotr Fabijański

2015-12-01

Full Text Available This paper describes a digital and actual model of the UPQC (Unified Power Quality Conditioner integrated system for power quality improvement. The UPQC’s design and its connection to an AC supply grid, 1-phase and 3-phase alike, provide effective compensation of unwanted interferences in the waveforms of load supply voltages and non-linear load currents. This article presents an overview of topologies and control strategies. The study of the UPQC confirmed its positive impact on the power quality. The electricity parameters were significantly improved. Total harmonic distortion in supply voltage THDu decreased six-fold to 1.89%, and total harmonic distortion in load current THDi decreased more than ten-fold to 2.38% for a non-linear load (uncontrolled bridge rectifier with load L. Additionally, symmetrisation of supply voltages and reactive power compensation Q of linear load was obtained. The UPQC integrated system for power quality improvement can be used wherever high-quality and PN-EN 50160 standard – compliant electricity is required.

Complexity Uncertainty Analysis of Dynamic in a Dual-Channel Energy Supply Chain Model with Heterogeneous Retailers

Directory of Open Access Journals (Sweden)

Ting Li

2015-01-01

Full Text Available This paper analyses the dynamics of dual-channel energy supply chain model with heterogeneous retailers (as regards the type of expectations’ formation. On the basis of analyzing the stabilities of four fixed points in the three-dimensional dynamic system, local stable regions of Nash equilibrium are obtained. Effects of S on the stable regions and profit are studied. Simulation results show that the adjustment of price speed has an obvious impact on the complexity of competition. The performances of the model in different period are measured by using the index of average profit. The results show that unstable behavior in economic system is often an unfavorable outcome. So this paper discusses the application of parameters control method when the model is in chaos and then allows the oligarchs to eliminate the negative effects.

Optimal transport on supply-demand networks.

Science.gov (United States)

Chen, Yu-Han; Wang, Bing-Hong; Zhao, Li-Chao; Zhou, Changsong; Zhou, Tao

2010-06-01

In the literature, transport networks are usually treated as homogeneous networks, that is, every node has the same function, simultaneously providing and requiring resources. However, some real networks, such as power grids and supply chain networks, show a far different scenario in which nodes are classified into two categories: supply nodes provide some kinds of services, while demand nodes require them. In this paper, we propose a general transport model for these supply-demand networks, associated with a criterion to quantify their transport capacities. In a supply-demand network with heterogeneous degree distribution, its transport capacity strongly depends on the locations of supply nodes. We therefore design a simulated annealing algorithm to find the near optimal configuration of supply nodes, which remarkably enhances the transport capacity compared with a random configuration and outperforms the degree target algorithm, the betweenness target algorithm, and the greedy method. This work provides a start point for systematically analyzing and optimizing transport dynamics on supply-demand networks.

Supply Chain Sourcing Game: A Negotiation Exercise

Science.gov (United States)

Gumus, Mehmet; Love, Ernie C.

2013-01-01

This article introduces an exercise that simulates the negotiation process in a dynamic supply chain. The retailer and wholesaler roles are assigned to student groups who negotiate supply contracts in a number of rounds during a class period. Each group makes pricing, inventory, and ordering decision concurrently, and competes with others to…

Estimation of time-varying reactivity by the H∞ optimal linear filter

International Nuclear Information System (INIS)

Suzuki, Katsuo; Shimazaki, Junya; Watanabe, Koiti

1995-01-01

The problem of estimating the time-varying net reactivity from flux measurements is solved for a point reactor kinetics model using a linear filtering technique in an H ∞ settings. In order to sue this technique, an appropriate dynamical model of the reactivity is constructed that can be embedded into the reactor model as one of its variables. A filter, which minimizes the H ∞ norm of the estimation error power spectrum, operates on neutron density measurements corrupted by noise and provides an estimate of the dynamic net reactivity. Computer simulations are performed to reveal the basic characteristics of the H ∞ optimal filter. The results of the simulation indicate that the filter can be used to determine the time-varying reactivity from neutron density measurements that have been corrupted by noise

SUPPLY CHAIN RISKS: LITERATURE REVIEW AND A NEW CATEGORIZATION

OpenAIRE

Er Kara, Merve; Oktay Fırat, Seniye Ümit

2017-01-01

Identification of risks is the first step to build a resilient and sustainable supply chain and develop proactive risk management strategies. Supply chains contain numerous risks with different forms, probabilities and impacts. Supply chain risks have a multi-dimensional nature and can result from a wide variety of sources including demand and supply variability, poor performing suppliers, price fluctuations, dynamic consumer markets, global economic uncertainty, and even unexpected events su...

Exploring the Impact of Network Structure and Demand Collaboration on the Dynamics of a Supply Chain Network Using a Robust Control Approach

Directory of Open Access Journals (Sweden)

Yongchang Wei

2015-01-01

uncertain environment. The impact of network structure and collaboration on the dynamics and robustness of supply chain network, however, remains to be explored. In this paper, a unified state space model for a two-layer supply chain network composed of multiple distributors and multiple retailers is developed. A robust control algorithm is advocated to reduce both order and demand fluctuations for unknown demand. Numerical simulations demonstrate that the robust control approach has the advantage to reduce both inventory and order fluctuations. In the simulation experiment, it is interesting to notice that complex network structure and collaborations might contribute to the reduction of inventory and order oscillations. This paper yields new insights into the overestimated bullwhip effect problem and helps us understand the complexities of supply chain networks.

Estimates of water source contributions in a dynamic urban water supply system inferred via a Bayesian stable isotope mixing model

Science.gov (United States)

Jameel, M. Y.; Brewer, S.; Fiorella, R.; Tipple, B. J.; Bowen, G. J.; Terry, S.

2017-12-01

Public water supply systems (PWSS) are complex distribution systems and critical infrastructure, making them vulnerable to physical disruption and contamination. Exploring the susceptibility of PWSS to such perturbations requires detailed knowledge of the supply system structure and operation. Although the physical structure of supply systems (i.e., pipeline connection) is usually well documented for developed cities, the actual flow patterns of water in these systems are typically unknown or estimated based on hydrodynamic models with limited observational validation. Here, we present a novel method for mapping the flow structure of water in a large, complex PWSS, building upon recent work highlighting the potential of stable isotopes of water (SIW) to document water management practices within complex PWSS. We sampled a major water distribution system of the Salt Lake Valley, Utah, measuring SIW of water sources, treatment facilities, and numerous sites within in the supply system. We then developed a hierarchical Bayesian (HB) isotope mixing model to quantify the proportion of water supplied by different sources at sites within the supply system. Known production volumes and spatial distance effects were used to define the prior probabilities for each source; however, we did not include other physical information about the supply system. Our results were in general agreement with those obtained by hydrodynamic models and provide quantitative estimates of contributions of different water sources to a given site along with robust estimates of uncertainty. Secondary properties of the supply system, such as regions of "static" and "dynamic" source (e.g., regions supplied dominantly by one source vs. those experiencing active mixing between multiple sources), can be inferred from the results. The isotope-based HB isotope mixing model offers a new investigative technique for analyzing PWSS and documenting aspects of supply system structure and operation that are

Stabilization Strategies of Supply Networks with Stochastic Switched Topology

Directory of Open Access Journals (Sweden)

Shukai Li

2013-01-01

Full Text Available In this paper, a dynamical supply networks model with stochastic switched topology is presented, in which the stochastic switched topology is dependent on a continuous time Markov process. The goal is to design the state-feedback control strategies to stabilize the dynamical supply networks. Based on Lyapunov stability theory, sufficient conditions for the existence of state feedback control strategies are given in terms of matrix inequalities, which ensure the robust stability of the supply networks at the stationary states and a prescribed H∞ disturbance attenuation level with respect to the uncertain demand. A numerical example is given to illustrate the effectiveness of the proposed method.

Designing a new supply chain for competition against an existing supply chain

NARCIS (Netherlands)

Rezapour, S.; Farahani, R.Z.; Dullaert, W.E.H.; de Borger, B.

2014-01-01

We develop a bi-level model for designing an entrant supply chain (SC) in the presence of a pre-existing competing SC where demand is elastic with respect to price and distance. The model assumes dynamic competition between the new and pre-existing SCs in retailers' level and probabilistic

"Bullwhip Effect" in Supply Chains

Directory of Open Access Journals (Sweden)

Anđelko Ščukanec

2007-09-01

Full Text Available The system which connects all the elements between theproducer and the consumer is called the supply chain. This definitionof the supply chain shows its complexity, dynamics anduncertainty. Successful operation of supply chains requires thebest possible coordination of its elements, which obviously indicatesthe utmost importance of the information flow alongthem. The operation of supply chains on the whole has to bemore successful than the operation of their individual elements.It should be noted that such a complex process may give rise toa series of problems, unwanted events, as well as substantial reductionin profits and the level of service. One of such unwantedphenomena which may occur in the supply chain is the"bullwhip effect". This is a possible increase in the diversity oforders which occurs when we move along the elements of thesupply chain (from the customers' orders to the producers' orders.The work analyses the processes within the supply chainsand the occurrence of the bullwhip effect. The main causes ofthe bullwhip effect that we encounter daily in the supply chainshave been clearly defined. The paper also presents the mainnegative consequences of such a disturbance within the supplychains, and provides possible solutions for avoiding the bullwhipeffect.

Housing demand or money supply? A new Keynesian dynamic stochastic general equilibrium model on China's housing market fluctuations

Science.gov (United States)

Wen, Xing-Chun; He, Ling-Yun

2015-08-01

There is a bitter controversy over what drives the housing price in China in the existing literature. In this paper, we investigate the underlying driving force behind housing price fluctuations in China, especially focusing on the role of housing demand shock with that of money supply shock in explaining housing price movements, by a new Keynesian dynamic stochastic general equilibrium model. Empirical results suggest that it is housing demand, instead of money supply, that mainly drives China's housing price movements. Relevant policy implication is further discussed, namely, whether to consider the housing price fluctuations in the conduct of monetary policy. By means of the policy simulations, we find that a real house price-augmented money supply rule is a better monetary policy for China's economy stabilization. 1. Investment refers to fixed capital investment. 2. Housing price refers to national average housing price. Quarterly data on housing price during the period of our work are not directly available. However, monthly data of the value of sales on housing and sale volume on housing can be directly obtained from National Bureau of Statistics of China. We add up the monthly data and calculate one quarter's housing price by dividing the value of housing sales by its sale volume in one quarter. 3. M2 means the broad money supply in China.

Dynamics of change in local physician supply: an ecological perspective.

Science.gov (United States)

Jiang, H Joanna; Begun, James W

2002-05-01

The purpose of this study is to employ an ecological framework to identify factors that have an impact on change in local physician supply within the USA. A particular specialty type of patient care physicians in a local market is defined as a physician population. Four physician populations are identified: generalists, medical specialists, surgical specialists, and hospital-based specialists. Based on population ecology theory, the proposed framework explains the growth of a particular physician population by four mechanisms: the intrinsic properties of this physician population; the local market's carrying capacity, which is determined by three environmental dimensions (munificence, concentration, diversity); competition within the same physician population; and interdependence between different physician populations. Data at the level of Metropolitan Statistical Areas (MSAs) were compiled from the US Area Resources File, the American Hospital Association Annual Surveys of Hospitals, the American Medical Association Census of Medical Groups, the InterStudy National HMO Census, and the US County Business Patterns. Changes in the number and percentage of physicians in a particular specialty population from 1985 to 1994 were regressed, respectively, on 1985-94 changes in the explanatory variables as well as their levels in 1985. The results indicate that the population ecology framework is useful in explaining dynamics of change in the local physician workforce. Variables measuring the three environmental dimensions were found to have significant, and in some cases, differential effects on change in the size of different specialty populations. For example, both hospital consolidation and managed care penetration showed significant positive eflects on growth of the generalist population but suppressing effects on growth of the specialist population. The percentage of physicians in a particular specialty population in 1985 was negatively related to change in the size

Reactive Molecular Dynamics Simulations to Understand Mechanical Response of Thaumasite under Temperature and Strain Rate Effects.

Science.gov (United States)

Hajilar, Shahin; Shafei, Behrouz; Cheng, Tao; Jaramillo-Botero, Andres

2017-06-22

Understanding the structural, thermal, and mechanical properties of thaumasite is of great interest to the cement industry, mainly because it is the phase responsible for the aging and deterioration of civil infrastructures made of cementitious materials attacked by external sources of sulfate. Despite the importance, effects of temperature and strain rate on the mechanical response of thaumasite had remained unexplored prior to the current study, in which the mechanical properties of thaumasite are fully characterized using the reactive molecular dynamics (RMD) method. With employing a first-principles based reactive force field, the RMD simulations enable the description of bond dissociation and formation under realistic conditions. From the stress-strain curves of thaumasite generated in the x, y, and z directions, the tensile strength, Young's modulus, and fracture strain are determined for the three orthogonal directions. During the course of each simulation, the chemical bonds undergoing tensile deformations are monitored to reveal the bonds responsible for the mechanical strength of thaumasite. The temperature increase is found to accelerate the bond breaking rate and consequently the degradation of mechanical properties of thaumasite, while the strain rate only leads to a slight enhancement of them for the ranges considered in this study.

Self-propagating exothermic reaction analysis in Ti/Al reactive films using experiments and computational fluid dynamics simulation

Energy Technology Data Exchange (ETDEWEB)

Sen, Seema, E-mail: seema.sen@tu-ilmenau.de [Technical University of Ilmenau, Department of Materials for Electronics, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany); Niederrhein University of Applied Science, Department of Mechanical and Process Engineering, Reinarzstraße 49, 47805 Krefeld (Germany); Lake, Markus; Kroppen, Norman; Farber, Peter; Wilden, Johannes [Niederrhein University of Applied Science, Department of Mechanical and Process Engineering, Reinarzstraße 49, 47805 Krefeld (Germany); Schaaf, Peter [Technical University of Ilmenau, Department of Materials for Electronics, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany)

2017-02-28

Highlights: • Development of nanoscale Ti/Al multilayer films with 1:1, 1:2 and 1:3 molar ratios. • Characterization of exothermic reaction propagation by experiments and simulation. • The reaction velocity depends on the ignition potentials and molar ratios of the films. • Only 1Ti/3Al films exhibit the unsteady reaction propagation with ripple formation. • CFD simulation shows the time dependent atom mixing and temperature flow during exothermic reaction. - Abstract: This study describes the self-propagating exothermic reaction in Ti/Al reactive multilayer foils by using experiments and computational fluid dynamics simulation. The Ti/Al foils with different molar ratios of 1Ti/1Al, 1Ti/2Al and 1Ti/3Al were fabricated by magnetron sputtering method. Microstructural characteristics of the unreacted and reacted foils were analyzed by using electronic and atomic force microscopes. After an electrical ignition, the influence of ignition potentials on reaction propagation has been experimentally investigated. The reaction front propagates with a velocity of minimum 0.68 ± 0.4 m/s and maximum 2.57 ± 0.6 m/s depending on the input ignition potentials and the chemical compositions. Here, the 1Ti/3Al reactive foil exhibits both steady state and unsteady wavelike reaction propagation. Moreover, the numerical computational fluid dynamics (CFD) simulation shows the time dependent temperature flow and atomic mixing in a nanoscale reaction zone. The CFD simulation also indicates the potentiality for simulating exothermic reaction in the nanoscale Ti/Al foil.

The coordination of calculation and experimental procedures in the determination of high-negative reactivities

International Nuclear Information System (INIS)

Pinegin, A.A.; Tsyganov, S.V.

1999-01-01

Usually three sources of information about the value of inserted negative reactivity (ρ) are used: dynamical experiment with reactimeters, solution of conventionally critical problems, and dynamical calculation of the process of reactivity insertion with the reactimeter model. Each of them gives they own estimation of ρ. The discrepancy between these estimations could be significant, particularly noticeable in dissymmetric insertion of perturbation. Origin of problems of estimation high negative reactivity is discussed using the reactivity meter. A correct method of high negative reactivity estimation have to include three dimensional dinamic core model for taking to account spatial effect. Moreover, some special processes, such as removal of delayed neutron emitters, change in the fraction of delayed neutrons, inner sources are considered etc. (author)

Integrated planning in supply chains with buy-side and sell-side

Indian Academy of Sciences (India)

Supply chain management; dynamic pricing; partner selection; supply chain planning; electronic marketplaces. Abstract. In this paper we develop a quadratic programming model for partner selection and planning in integrated supply chain networks embedded with both sell-side and buy-side electronic marketplaces.

Distribution factors for reactive power in the presence of bilateral transactions

International Nuclear Information System (INIS)

De Tuglie, E.; Torelli, F.

2004-01-01

The twin factors of limited investment in electric transmission systems and the overexploitation of electrical resources results in an increase in the need for reactive power to support system voltage profile and to supply loads. It is reasonable to expect that generators and compensators, heavily involved in reactive support on a voluntary basis, will be remunerated for their service by market transactions. This remuneration will depend on the network topology, i.e. of buyers, sellers and reactive injection locations, on the active power exchanged and the reactive power required by loads. All these aspects are taken into account in developing a methodology based on circuit considerations. Using this approach, at a given system operating point characterised by a predefined set of transactions, reactive responsibilities can be formulated as the sum of two terms: one strictly related to transactions and the other dependent on electric network parameters. Test results demonstrate the efficacy of the proposed methodology in sharing reactive power responsibilities in a fair way among market participants. (author)

Effects of externally supplied lithium on the suppression of ASR expansion in mortars

International Nuclear Information System (INIS)

Kawamura, Mitsunori; Kodera, Takeshi

2005-01-01

Lithium salts are being externally supplied for mitigating the progress of deterioration of ASR-affected concrete structures. However, it is not clear whether the sodium or potassium in the ASR gel in concrete is replaced by the lithium supplied from the outside. In this article, we examine changes in the composition of the ASR gel, previously formed in mortar specimens, after they are immersed in LiOH solution, using backscattered electron (BSE) imaging and energy-dispersive X-ray (EDX) analysis, associated with length change measurement of the mortar prisms. The intrusion of lithium ions into mortar specimens containing a reactive aggregate could arrest their further expansion within a relatively short time after immersion in 0.50 N LiOH solution. The alkali ions incorporated in most ASR gels, located not far away from interfaces between the cement paste and reactive aggregate particles, appear to be replaced by the lithium ions supplied from the solution. However, the ASR gel within the reacted aggregate particles did not appear to have been affected by the lithium ions

Designing a mathematical model for integrating dynamic cellular manufacturing into supply chain system

Science.gov (United States)

Aalaei, Amin; Davoudpour, Hamid

2012-11-01

This article presents designing a new mathematical model for integrating dynamic cellular manufacturing into supply chain system with an extensive coverage of important manufacturing features consideration of multiple plants location, multi-markets allocation, multi-period planning horizons with demand and part mix variation, machine capacity, and the main constraints are demand of markets satisfaction in each period, machine availability, machine time-capacity, worker assignment, available time of worker, production volume for each plant and the amounts allocated to each market. The aim of the proposed model is to minimize holding and outsourcing costs, inter-cell material handling cost, external transportation cost, procurement & maintenance and overhead cost of machines, setup cost, reconfiguration cost of machines installation and removal, hiring, firing and salary worker costs. Aimed to prove the potential benefits of such a design, presented an example is shown using a proposed model.

Dynamic behavior of reactive aluminum nanoparticle-fluorinated acrylic (AlFA) polymer composites

Science.gov (United States)

Crouse, Christopher A.; White, Brad; Spowart, Jonathan E.

2011-06-01

The dynamic behavior of aluminum nanoparticle-fluorinated acrylic (AlFA) composite materials has been explored under high strain rates. Cylindrical pellets of the AlFA composite materials were mounted onto copper sabots and impacted against a rigid anvil at velocities between 100 and 400 m/s utilizing a Taylor gas gun apparatus to achieve strain rates on the order of 104 /s. A framing camera was used to record the compaction and reaction events that occurred upon contact of the pellet with the anvil. Under both open air and vacuum environments the AlFA composites demonstrated high reactivity suggesting that the particles are primarily reacting with the fluorinated matrix. We hypothesize, based upon the compaction history of these materials, that reaction is initiated when the oxide shells on the aluminum nanoparticles are broken due an interparticle contact deformation process. We have investigated this hypothesis through altering the particle loading in the AlFA composites as well as impact velocities. This data and the corresponding trends will be presented in detail.

Extending supply chain risk and resilience frameworks to manage cyber risk

DEFF Research Database (Denmark)

Sepúlveda Estay, Daniel Alberto; Khan, Omera

This paper proposes two complementary tools for the description and quantification of dynamic effects arising from supply chain cyber-attacks. The first tool proposes a comprehensive analysis of the problem space through system dynamics methods, to identify explicitly mental models regarding...... aspects such as stakeholders, relevant relationships, feedback effects and potential policy levers. The second tool is proposed as a way of transitioning towards a dynamic analysis of the problem of cyber-attacks on supply chains, and is complementary to existing risk analysis tools....

Modeling the sorption dynamics of NaH using a reactive force field

International Nuclear Information System (INIS)

Ojwang, J. G. O.; Santen, Rutger van; Kramer, Gert Jan; Duin, Adri C. T. van; Goddard, William A. III

2008-01-01

We have parametrized a reactive force field for NaH, ReaxFF NaH , against a training set of ab initio derived data. To ascertain that ReaxFF NaH is properly parametrized, a comparison between ab initio heats of formation of small representative NaH clusters with ReaxFF NaH was done. The results and trend of ReaxFF NaH are found to be consistent with ab initio values. Further validation includes comparing the equations of state of condensed phases of Na and NaH as calculated from ab initio and ReaxFF NaH . There is a good match between the two results, showing that ReaxFF NaH is correctly parametrized by the ab initio training set. ReaxFF NaH has been used to study the dynamics of hydrogen desorption in NaH particles. We find that ReaxFF NaH properly describes the surface molecular hydrogen charge transfer during the abstraction process. Results on heat of desorption versus cluster size shows that there is a strong dependence on the heat of desorption on the particle size, which implies that nanostructuring enhances desorption process. To gain more insight into the structural transformations of NaH during thermal decomposition, we performed a heating run in a molecular dynamics simulation. These runs exhibit a series of drops in potential energy, associated with cluster fragmentation and desorption of molecular hydrogen. This is consistent with experimental evidence that NaH dissociates at its melting point into smaller fragments

The dynamic simulation model of soybean in Central Java to support food self sufficiency: A supply chain perspective

Science.gov (United States)

Oktyajati, Nancy; Hisjam, Muh.; Sutopo, Wahyudi

2018-02-01

Consider food become one of the basic human needs in order to survive so food sufficiency become very important. Food sufficiency of soybean commodity in Central Java still depends on imported soybean. Insufficiency of soybean because of there is much gap between local soybean productions and its demand. In the year 2016 the shortage of supply soybean commodity as much 68.79%. Soybean is an important and strategic commodity after rice and corn. The increasing consumption of soybean is related to increasing population, increasing incomes, changing of healthy life style. The aims of this study are to determine the soybean dynamic model based on supply chain perspective, define the proper price of local soybean to trigger increasing of local production, and to define the alternative solution to support food self sufficiency. This study will capture the real condition into dynamics model, then simulate a series of scenario into a computer program to obtain the best results. This study will be conducted the following first scenario with government intervention policy and second without government intervention policy. The best solution of the alternative can be used as government consideration for governmental policy. The results of the propose scenarios showed that self sufficiency on soybean can be achieved after the next 20 years by increasing planting area 4% and land productivity 1% per year.

Research on the Governance Mechanism of Aviation Complex Product Manufacturing Supply Chain Based on Dynamic Game Theory

Directory of Open Access Journals (Sweden)

Wang Nan

2016-01-01

Full Text Available In the manufacturing process of aeronautical complex products, for the following problems: develop long production cycle, a large number of ancillary products, a plurality of participating units, etc, and the status of the frequency of quality problems, using single-phase static game model in the case of asymmetric information, study on Supplier Quality insufficient investment, which resulting in opportunistic behaviour reasons. And using KMRW dynamic game model, we quantitative analysis the mechanism and crucial role of reputation mechanisms to ensure aeronautical complex product manufacturing supply chain and effective operation.

Ripple characteristic of the main ring magnet power supply for the KEK 12 GeV PS

International Nuclear Information System (INIS)

Sato, Hikaru; Sueno, Tuyosi; Mikawa, Katsuhiko

1995-01-01

First of all, general description of the main ring magnet power supply for the KEK 12 GeV PS will be described. The main power supply consists of thyristor rectifiers, DC filters, reactive power compensators, AC harmonic filters and control systems. Devices and control systems for suppressing ripple component of magnet field will be described. (author)

Development of EEM based silicon–water and silica–water wall potentials for non-reactive molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Kim, Junghan; Iype, Eldhose; Frijns, Arjan J.H.; Nedea, Silvia V.; Steenhoven, Anton A. van

2014-07-01

Molecular dynamics simulations of heat transfer in gases are computationally expensive when the wall molecules are explicitly modeled. To save computational time, an implicit boundary function is often used. Steele's potential has been used in studies of fluid–solid interface for a long time. In this work, the conceptual idea of Steele's potential was extended in order to simulate water–silicon and water–silica interfaces. A new wall potential model is developed by using the electronegativity-equalization method (EEM), a ReaxFF empirical force field and a non-reactive molecular dynamics package PumMa. Contact angle simulations were performed in order to validate the wall potential model. Contact angle simulations with the resulting tabulated wall potentials gave a silicon–water contact angle of 129°, a quartz–water contact angle of 0°, and a cristobalite–water contact angle of 40°, which are in reasonable agreement with experimental values.

The Supply Chain Triangle: How Synchronisation, Stability, and Productivity of Material Flows Interact

Directory of Open Access Journals (Sweden)

Florian Klug

2013-01-01

Full Text Available Empirical evidence created a commonly accepted understanding that synchronisation and stability of material flows impact its productivity. This crucial link between synchronous and stable material flows by time and quantity to create a supply chain with the highest throughput rates is at the heart of lean thinking. Although this supply chain triangle has generally been acknowledged over many years, it is necessary to reach a finer understanding of these dynamics. Therefore, we will develop and study supply chains with the help of fluid dynamics. A multistage, continuous material flow is modelled through a conservation law for material density. Unlike similar approaches, our model is not based on some quasi steady-state assumptions about the stochastic behaviour of the involved supply chain but rather on a simple deterministic rule for material flow density. These models allow us to take into account the nonlinear, dynamical interactions of different supply chain echelons and to test synchronised and stable flow with respect to its potential impacts. Numerical simulations verify that the model is able to simulate transient supply chain phenomena. Moreover, a quantification method relating to the fundamental link between synchronisation, stability, and productivity of supply chains has been found.

Virtualization of food supply chains with the internet of things

NARCIS (Netherlands)

Verdouw, C.N.; Wolfert, J.; Beulens, A.J.M.; Rialland, A.

2016-01-01

Internet technologies allow supply chains to use virtualizations dynamically in operational management processes. This will improve support for food companies in dealing with perishable products, unpredictable supply variations and stringent food safety and sustainability requirements.

Demand-supply dynamics in tourism systems: A spatio-temporal GIS analysis. The Alberta ski industry case study

Science.gov (United States)

Bertazzon, Stefania

The present research focuses on the interaction of supply and demand of down-hill ski tourism in the province of Alberta. The main hypothesis is that the demand for skiing depends on the socio-economic and demographic characteristics of the population living in the province and outside it. A second, consequent hypothesis is that the development of ski resorts (supply) is a response to the demand for skiing. From the latter derives the hypothesis of a dynamic interaction between supply (ski resorts) and demand (skiers). Such interaction occurs in space, within a range determined by physical distance and the means available to overcome it. The above hypotheses implicitly define interactions that take place in space and evolve over time. The hypotheses are tested by temporal, spatial, and spatio-temporal regression models, using the best available data and the latest commercially available software. The main purpose of this research is to explore analytical techniques to model spatial, temporal, and spatio-temporal dynamics in the context of regional science. The completion of the present research has produced more significant contributions than was originally expected. Many of the unexpected contributions resulted from theoretical and applied needs arising from the application of spatial regression models. Spatial regression models are a new and largely under-applied technique. The models are fairly complex and a considerable amount of preparatory work is needed, prior to their specification and estimation. Most of this work is specific to the field of application. The originality of the solutions devised is increased by the lack of applications in the field of tourism. The scarcity of applications in other fields adds to their value for other applications. The estimation of spatio-temporal models has been only partially attained in the present research. This apparent limitation is due to the novelty and complexity of the analytical methods applied. This opens new

Supply Chain Simulation : A Survey

NARCIS (Netherlands)

Kleijnen, J.P.C.

2003-01-01

This paper provides a survey of simulation in supply chain management.It reviews four types of simulation, namely spreadsheet simulation, system dynamics, discreteevent simulation, and business games.Which simulation type should be applied, depends on the type of managerial question to be answered

Joint Labour Supply Dynamics of Older Couples

NARCIS (Netherlands)

Michaud, P.C.

2003-01-01

This paper studies the labour force participation dynamics of older couples in the United States.Longitudinal data from the five available waves of the Health and Retirement Study (HRS) is used to investigate if the dynamics introduced by considering both spouses' behavior provide additional

Can Evolution Supply What Ecology Demands?

Science.gov (United States)

Kokko, Hanna; Chaturvedi, Anurag; Croll, Daniel; Fischer, Martin C; Guillaume, Frédéric; Karrenberg, Sophie; Kerr, Ben; Rolshausen, Gregor; Stapley, Jessica

2017-03-01

A simplistic view of the adaptive process pictures a hillside along which a population can climb: when ecological 'demands' change, evolution 'supplies' the variation needed for the population to climb to a new peak. Evolutionary ecologists point out that this simplistic view can be incomplete because the fitness landscape changes dynamically as the population evolves. Geneticists meanwhile have identified complexities relating to the nature of genetic variation and its architecture, and the importance of epigenetic variation is under debate. In this review, we highlight how complexity in both ecological 'demands' and the evolutionary 'supply' influences organisms' ability to climb fitness landscapes that themselves change dynamically as evolution proceeds, and encourage new synthetic effort across research disciplines towards ecologically realistic studies of adaptation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cement reactivity in CO2 saturated brines: use of a reactive transport code to highlight key degradation mechanisms

International Nuclear Information System (INIS)

Huet, B.M.; Prevost, J.H.; Scherer, G.W.

2007-01-01

A modular reactive transport code is proposed to analyze the reactivity of cement in CO 2 saturated brine. The coupling of the transport module and the geochemical module within Dynaflow TM is derived. Both modules are coupled in a sequential iterative approach to accurately model: (1) mineral dissolution/precipitation and (2) porosity dependent transport properties. Results of the model reproduce qualitatively the dissolution of cement hydrates (C-H, C-S-H, AFm, AFt) and intermediate products (CaCO 3 ) into the brine. Slight discrepancies between modeling and experimental results were found concerning the dynamics of the mineral zoning. Results suggest that the power law relationship to model effective transport properties from porosity values is not accurate for very reactive case. (authors)

Molecular dynamics calculation of thermophysical properties for a highly reactive liquid.

Science.gov (United States)

Wang, H P; Luo, B C; Wei, B

2008-10-01

In order to further understand the physical characteristics of liquid silicon, the thermophysical properties are required over a broad temperature range. However, its high reactivity brings about great difficulties in the experimental measurement. Here we report the thermophysical properties by molecular dynamics calculation, including density, specific heat, diffusion coefficient, and surface tension. The calculation is performed with a system consisting of 64,000 atoms, and employing the Stillinger-Weber (SW) potential model and the modified embedded atom method (MEAM) potential model. The results show that the density increases as a quadratic function of undercooling, and the value calculated by SW potential model is only 2-4 % smaller than the reported experimental data. The specific heat is obtained to be 30.95 J mol;{-1}K;{-1} by SW potential model and 32.50 J mol;{-1}K;{-1} by MEAM potential model, both of which are constants in the corresponding ranges of temperature. The self-diffusion coefficient is exponentially dependent on the temperature and consistent with the Arrhenius equation. The surface tension increases linearly with the rise of undercooling and agrees well with the reported experimental results. This work provides reasonable data in much wider temperature range, especially for the undercooled metastable state.

Reactive probing of macroscopically quantum mechanical SQUID rings

International Nuclear Information System (INIS)

Prance, R.J.; Clark, T.D.; Whiteman, R.; Diggins, J.; Ralph, J.F.; Prance, H.; Spiller, T.P.; Widom, A.; Srivastava, Y.

1994-01-01

In this paper we demonstrate that the energy level structure of ultra small capacitance SQUID rings can be probed adiabatically at radio frequency using both dynamical and quasistatic reactive techniques. ((orig.))

Redox state, reactive oxygen species and adaptive growth in colonial hydroids.

Science.gov (United States)

Blackstone, N W

2001-06-01

Colonial metazoans often encrust surfaces over which the food supply varies in time or space. In such an environment, adaptive colony development entails adjusting the timing and spacing of feeding structures and gastrovascular connections to correspond to this variable food supply. To investigate the possibility of such adaptive growth, within-colony differential feeding experiments were carried out using the hydroid Podocoryna carnea. Indeed, such colonies strongly exhibited adaptive growth, developing dense arrays of polyps (feeding structures) and gastrovascular connections in areas that were fed relative to areas that were starved, and this effect became more consistent over time. To investigate mechanisms of signaling between the food supply and colony development, measurements were taken of metabolic parameters that have been implicated in signal transduction in other systems, particularly redox state and levels of reactive oxygen species. Utilizing fluorescence microscopy of P. carnea cells in vivo, simultaneous measurements of redox state [using NAD(P)H] and hydrogen peroxide (using 2',7'-dichlorofluorescin diacetate) were taken. Both measures focused on polyp epitheliomuscular cells, since these exhibit the greatest metabolic activity. Colonies 3-5h after feeding were relatively oxidized, with low levels of peroxide, while colonies 24h after feeding were relatively reduced, with high levels of peroxide. The functional role of polyps in feeding and generating gastrovascular flow probably produced this dichotomy. Polyps 3-5h after feeding contract maximally, and this metabolic demand probably shifts the redox state in the direction of oxidation and diminishes levels of reactive oxygen species. In contrast, 24h after feeding, polyps are quiescent, and this lack of metabolic demand probably shifts the redox state in the direction of reduction and increases levels of reactive oxygen species. Within-colony differential feeding experiments were carried out on

Exploring the Dynamics of Globalization: Supply Chain Vulnerability to Natural Disasters

Science.gov (United States)

Kalafsky, Ronald V.; Conner, Neil

2015-01-01

Global supply chains play an increasingly important role in the economy and should therefore be addressed within geography coursework, especially given concerns that geographers have not fully explored various angles of globalization. This article explores the use of an online case study on supply chains and their vulnerability to natural…

Supply chain configuration concepts, solutions, and applications

CERN Document Server

Chandra, Charu

2016-01-01

This book discusses the models and tools available for solving configuration problems, emphasizes the value of model integration to obtain comprehensive and robust configuration decisions, proposes solutions for supply chain configuration in the presence of stochastic and dynamic factors, and illustrates application of the techniques discussed in applied studies. It is divided into four parts, which are devoted to defining the supply chain configuration problem and identifying key issues, describing solutions to various problems identified, proposing technologies for enabling supply chain confirmations, and discussing applied supply chain configuration problems. Its distinguishing features are: an explicit focus on the configuration problem an in-depth coverage of configuration models an emphasis on model integration and application of information modeling techniques in decision-making New to this edition is Part II: Technologies, which introduces readers to various technologies being utilized for supply chai...

Control units for APS power supplies

International Nuclear Information System (INIS)

Despe, O.D.; Saunders, C.; McGhee, D.G.

1993-01-01

The Advanced Photon Source (APS) accelerator facility is made up of five major subsystems in addition to the linac: the positron accumulator ring (PAR), low energy transport (LET), booster synchrotron (SYNCH), high energy transport (HET), the storage ring (SR). Each subsystem has multiple magnet power supply combinations, some requiring multiple of operation. These magnet and power supply combinations computer controlled and monitored. The power supply control unit (PSCU) is the first layer of hardware and software above the power supply itself and is described in this paper. The description includes the basic philosophy for each of operation and how it influences the topology and of implementing control. The design of the analog reference blocks (ARBs) influenced the design of other custom functions well as the feedback controls for vibration and other dynamic corrections. The command set supported by the PSCU is discussed

A dynamic perspective of the geopolitical supply risk of metals

DEFF Research Database (Denmark)

Habib, Komal; Hamelin, Lorie; Wenzel, Henrik

2016-01-01

. In the context of strategic planning and innovation, and in scientific literature, this aspect is often referred to as geopolitical supply risk. In the past few decades, cobalt crisis, the oil embargo, and the more recent Rare Earth Elements (REEs) issue are the best examples regarding the geopolitical supply...... production distribution and more dependent on the location of current geological resources and the future discoveries, as well as on the technological development to improve profitability of mining the currently sub-economical resources....

Dealing with uncertainty in modeling intermittent water supply

Science.gov (United States)

Lieb, A. M.; Rycroft, C.; Wilkening, J.

2015-12-01

Intermittency in urban water supply affects hundreds of millions of people in cities around the world, impacting water quality and infrastructure. Building on previous work to dynamically model the transient flows in water distribution networks undergoing frequent filling and emptying, we now consider the hydraulic implications of uncertain input data. Water distribution networks undergoing intermittent supply are often poorly mapped, and household metering frequently ranges from patchy to nonexistent. In the face of uncertain pipe material, pipe slope, network connectivity, and outflow, we investigate how uncertainty affects dynamical modeling results. We furthermore identify which parameters exert the greatest influence on uncertainty, helping to prioritize data collection.

Analysis of ways to control the supply of the blast, and their impact on gas-dynamic processes in the blast furnace

Directory of Open Access Journals (Sweden)

Віктор Петрович Кравченко

2016-07-01

Full Text Available The article presents the analysis of two methods of control over hot blast supply into a blast furnace with constant pressure and constant amount (consumption. The analysis of these two methods was performed with the aim of determining their influence upon changes in gas pressure in the blast furnace top. The blast furnace was considered as a unity of vessels (furnace hearth, the top and gas-dynamic resistance (a column of charge materials. A differential equation was obtained, with regard to the dynamic balance of gas flow at the inlet and outlet of the top; the equation relates the pressure and gas consumption at the top to the pressure and hot blast consumption at the inlet and outlet of the furnace and to the resistance of the column of charge materials. The column of charge materials is considered as n-th number of channels through which gas flow inside the furnace moves and which resist to the flow. By the analysis of this equation at steady state (automatic stabilization of gas pressure in the top, the conditions were obtained to be satisfied with the specified value of gas pressure in the top. This value is equal to a half of the sum of the value of hot blast pressure at the inlet into the furnace and the value of pressure inside the collector of blast furnace gas. This conclusion is verified by the operation practice of blast furnaces in Ukraine. While analyzing the second method of controlling the supply of blast supply-stabilization of consumption (amount of hot blast supplied into the furnace it has been shown that the method could be realized in condition of stabilization of the amount of blast furnace gas, going out of the furnace. As the resistance of the column of charge materials constantly changes it is necessary to change the hot blast pressure in order to ensure the constant amount of blast, supplied into the furnace. It is often connected with possible substantial pressure fluctuations of hot blast at the inlet of the

Towards a dynamic model of supply chain regimes for complex multi-agent markets

NARCIS (Netherlands)

Hogenboom, A.C.; Hogenboom, F.P.; Kaymak, U.; Ketter, W.; Dalen, van Jan; Collins, J.

2010-01-01

Information systems are crucial for effective supply chain management in today's complex supply chains for durable goods. Complex decision making processes on strategic, tactical, and operational level require substantial support in order to contribute to the agility of organizations. Supply chain

Reactivity estimation using digital nonlinear H∞ estimator for VHTRC experiment

International Nuclear Information System (INIS)

Suzuki, Katsuo; Nabeshima, Kunihiko; Yamane, Tsuyoshi

2003-01-01

On-line and real-time estimation of time-varying reactivity in a nuclear reactor in necessary for early detection of reactivity anomaly and safe operation. Using a digital nonlinear H ∞ estimator, an experiment of real-time dynamic reactivity estimation was carried out in the Very High Temperature Reactor Critical Assembly (VHTRC) of Japan Atomic Energy Research Institute. Some technical issues of the experiment are described, such as reactivity insertion, data sampling frequency, anti-aliasing filter, experimental circuit and digitalising nonlinear H ∞ reactivity estimator, and so on. Then, we discussed the experimental results obtained by the digital nonlinear H ∞ estimator with sampled data of the nuclear instrumentation signal for the power responses under various reactivity insertions. Good performances of estimated reactivity were observed, with almost no delay to the true reactivity and sufficient accuracy between 0.05 cent and 0.1 cent. The experiment shows that real-time reactivity for data sampling period of 10 ms can be certainly realized. From the results of the experiment, it is concluded that the digital nonlinear H ∞ reactivity estimator can be applied as on-line real-time reactivity meter for actual nuclear plants. (author)

Knowledge management system for risk mitigation in supply chain uncertainty: case from automotive battery supply chain

Science.gov (United States)

Marie, I. A.; Sugiarto, D.; Surjasa, D.; Witonohadi, A.

2018-01-01

Automotive battery supply chain include battery manufacturer, sulphuric acid suppliers, polypropylene suppliers, lead suppliers, transportation service providers, warehouses, retailers and even customers. Due to the increasingly dynamic condition of the environment, supply chain actors were required to improve their ability to overcome various uncertainty issues in the environment. This paper aims to describe the process of designing a knowledge management system for risk mitigation in supply chain uncertainty. The design methodology began with the identification of the knowledge needed to solve the problems associated with uncertainty and analysis of system requirements. The design of the knowledge management system was described in the form of a data flow diagram. The results of the study indicated that key knowledge area that needs to be managed were the knowledge to maintain the stability of process in sulphuric acid process and knowledge to overcome the wastes in battery manufacturing process. The system was expected to be a media acquisition, dissemination and storage of knowledge associated with the uncertainty in the battery supply chain and increase the supply chain performance.

Virtualization of food supply chains with the internet of things

OpenAIRE

Verdouw, C.N.; Wolfert, J.; Beulens, A.J.M.; Rialland, A.

2016-01-01

Internet technologies allow supply chains to use virtualizations dynamically in operational management processes. This will improve support for food companies in dealing with perishable products, unpredictable supply variations and stringent food safety and sustainability requirements. Virtualization enables supply chain actors to monitor, control, plan and optimize business processes remotely and in real-time through the Internet, based on virtual objects instead of observation on-site. This...

A modular approach for RFX D.C. power supplies

International Nuclear Information System (INIS)

Bolognani, S.; Ciscato, D.; Tenti, P.

1981-01-01

A modular approach to the realization of D.C. Power Supplies of the Reverse Field Pinch Experiment (RFX) is presented. A basic convertor module configuration is proposed which enables a high flexibility of the power supply system to be obtained, as required to cope with the plasma behaviour uncertainties. The basic convertor module rating has been selected to meet all the expected load requirements and a preliminary design of the convertor has been carried out for evaluating the technical and economical feasibility of the system. Different fault conditions have been analyzed and protective devices have been devised accordingly. Finally simulated profiles of the active and reactive power drawn from the AC mains are reported. (author)

North American demand and supply dynamics - implications for pricing

International Nuclear Information System (INIS)

George, R.

1998-01-01

Key issues regarding the natural gas industry and the long-term outlook for North American supply and demand for natural gas were discussed. The North American market was characterized as not a mature market, meaning that demand will continue to increase in the coming years. It was confidently predicted that supplies will be available for development at reasonable costs. However, real prices will slowly increase over time. Short-term fundamentals, expectations and pricing outlook were also discussed. The influence of upstream activity levels, the health of the economy, weather and storage were all identified as factors that will impact on short-term price expectations. According to this author a minor increase in price may be expected during the winter of 1998/1999. tabs., figs

PuReMD-GPU: A reactive molecular dynamics simulation package for GPUs

International Nuclear Information System (INIS)

Kylasa, S.B.; Aktulga, H.M.; Grama, A.Y.

2014-01-01

We present an efficient and highly accurate GP-GPU implementation of our community code, PuReMD, for reactive molecular dynamics simulations using the ReaxFF force field. PuReMD and its incorporation into LAMMPS (Reax/C) is used by a large number of research groups worldwide for simulating diverse systems ranging from biomembranes to explosives (RDX) at atomistic level of detail. The sub-femtosecond time-steps associated with ReaxFF strongly motivate significant improvements to per-timestep simulation time through effective use of GPUs. This paper presents, in detail, the design and implementation of PuReMD-GPU, which enables ReaxFF simulations on GPUs, as well as various performance optimization techniques we developed to obtain high performance on state-of-the-art hardware. Comprehensive experiments on model systems (bulk water and amorphous silica) are presented to quantify the performance improvements achieved by PuReMD-GPU and to verify its accuracy. In particular, our experiments show up to 16× improvement in runtime compared to our highly optimized CPU-only single-core ReaxFF implementation. PuReMD-GPU is a unique production code, and is currently available on request from the authors

PuReMD-GPU: A reactive molecular dynamics simulation package for GPUs

Energy Technology Data Exchange (ETDEWEB)

Kylasa, S.B., E-mail: skylasa@purdue.edu [Department of Elec. and Comp. Eng., Purdue University, West Lafayette, IN 47907 (United States); Aktulga, H.M., E-mail: hmaktulga@lbl.gov [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, MS 50F-1650, Berkeley, CA 94720 (United States); Grama, A.Y., E-mail: ayg@cs.purdue.edu [Department of Computer Science, Purdue University, West Lafayette, IN 47907 (United States)

2014-09-01

We present an efficient and highly accurate GP-GPU implementation of our community code, PuReMD, for reactive molecular dynamics simulations using the ReaxFF force field. PuReMD and its incorporation into LAMMPS (Reax/C) is used by a large number of research groups worldwide for simulating diverse systems ranging from biomembranes to explosives (RDX) at atomistic level of detail. The sub-femtosecond time-steps associated with ReaxFF strongly motivate significant improvements to per-timestep simulation time through effective use of GPUs. This paper presents, in detail, the design and implementation of PuReMD-GPU, which enables ReaxFF simulations on GPUs, as well as various performance optimization techniques we developed to obtain high performance on state-of-the-art hardware. Comprehensive experiments on model systems (bulk water and amorphous silica) are presented to quantify the performance improvements achieved by PuReMD-GPU and to verify its accuracy. In particular, our experiments show up to 16× improvement in runtime compared to our highly optimized CPU-only single-core ReaxFF implementation. PuReMD-GPU is a unique production code, and is currently available on request from the authors.

The dynamics of Al/Pt reactive multilayer ignition via pulsed-laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Murphy, Ryan D.; Reeves, Robert V.; Yarrington, Cole D.; Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

2015-12-07

Reactive multilayers consisting of alternating layers of Al and Pt were irradiated by single laser pulses ranging from 100 μs to 100 ms in duration, resulting in the initiation of rapid, self-propagating reactions. The threshold intensities for ignition vary with the focused laser beam diameter, bilayer thickness, and pulse length and are affected by solid state reactions and conduction of heat away from the irradiated regions. High-speed photography was used to observe ignition dynamics during irradiation and elucidate the effects of heat transfer into a multilayer foil. For an increasing laser pulse length, the ignition process transitioned from a more uniform to a less uniform temperature profile within the laser-heated zone. A more uniform temperature profile is attributed to rapid heating rates and heat localization for shorter laser pulses, and a less uniform temperature profile is due to slower heating of reactants and conduction during irradiation by longer laser pulses. Finite element simulations of laser heating using measured threshold intensities indicate that micron-scale ignition of Al/Pt occurs at low temperatures, below the melting point of both reactants.

Cement reactivity in CO{sub 2} saturated brines: use of a reactive transport code to highlight key degradation mechanisms

Energy Technology Data Exchange (ETDEWEB)

Huet, B.M.; Prevost, J.H.; Scherer, G.W. [Princeton Univ., NJ (United States)

2007-07-01

A modular reactive transport code is proposed to analyze the reactivity of cement in CO{sub 2} saturated brine. The coupling of the transport module and the geochemical module within Dynaflow{sup TM} is derived. Both modules are coupled in a sequential iterative approach to accurately model: (1) mineral dissolution/precipitation and (2) porosity dependent transport properties. Results of the model reproduce qualitatively the dissolution of cement hydrates (C-H, C-S-H, AFm, AFt) and intermediate products (CaCO{sub 3}) into the brine. Slight discrepancies between modeling and experimental results were found concerning the dynamics of the mineral zoning. Results suggest that the power law relationship to model effective transport properties from porosity values is not accurate for very reactive case. (authors)

Development of a faulty reactivity detection system applying a digital H∞ estimator

International Nuclear Information System (INIS)

Suzuki, Katsuo; Suzudo, Tomoaki; Nabeshima, Kunihiko

2004-01-01

This paper concerns an application of digital optimal H ∞ estimator to the detection of faulty reactivity in real-time. The detection system, fundamentally based on the reactivity balance method, is composed of three modules, i.e. the net reactivity estimator, the feedback reactivity estimator and the reactivity balance circuit. H ∞ optimal filters are used for these two reactivity estimators, and the nonlinear neutronics are taken into consideration especially for the design of the net reactivity estimator. A series of performance test of the detection system are conducted by using numerical simulations of reactor dynamics with the insertion of a faulty reactivity for an experimental fast breeder reactor JOYO. The system detects the typical artificial reactivity insertions during a few seconds with no stationary offset and the accuracy of 0.1 cent, and is satisfactory for its practical use. (author)

Identifying sources of uncertainty to generate supply chain redesign strategies

NARCIS (Netherlands)

Vorst, van der J.G.A.J.; Beulens, A.J.M.

2002-01-01

Dynamic demands and constraints imposed by a rapidly changing business environment make it increasingly necessary for companies in the food supply chain to cooperate with each other. The main questions individual (food) companies face are whether, why, how and with whom they should start supply

SCRAM reactivity calculations with the KIKO3D code

International Nuclear Information System (INIS)

Hordosy, G.; Kerszturi, A.; Maraczy, Cs.; Temesvari, E.

1999-01-01

Discrepancies between calculated static reactivities and measured reactivities evaluated with reactivity meters led to investigating SCRAM with the KIKO3D dynamic code, The time and space dependent neutron flux in the reactor core during the rod drop measurement was calculated by the KIKO3D nodal diffusion code. For calculating the ionisation chamber signals the Green function technique was applied. The Green functions of ionisation chambers were evaluated via solving the neutron transport equation in the reflector regions with the MCNP Monte Carlo code. The detector signals during asymmetric SCRAM measurements were calculated and compared with measured data using the inverse point kinetics transformation. The sufficient agreement validates the KIKO3D code to determine the reactivities after SCRAM. (Authors)

Voltage equilibration for reactive atomistic simulations of electrochemical processes

International Nuclear Information System (INIS)

Onofrio, Nicolas; Strachan, Alejandro

2015-01-01

We introduce electrochemical dynamics with implicit degrees of freedom (EChemDID), a model to describe electrochemical driving force in reactive molecular dynamics simulations. The method describes the equilibration of external electrochemical potentials (voltage) within metallic structures and their effect on the self-consistent partial atomic charges used in reactive molecular dynamics. An additional variable assigned to each atom denotes the local potential in its vicinity and we use fictitious, but computationally convenient, dynamics to describe its equilibration within connected metallic structures on-the-fly during the molecular dynamics simulation. This local electrostatic potential is used to dynamically modify the atomic electronegativities used to compute partial atomic changes via charge equilibration. Validation tests show that the method provides an accurate description of the electric fields generated by the applied voltage and the driving force for electrochemical reactions. We demonstrate EChemDID via simulations of the operation of electrochemical metallization cells. The simulations predict the switching of the device between a high-resistance to a low-resistance state as a conductive metallic bridge is formed and resistive currents that can be compared with experimental measurements. In addition to applications in nanoelectronics, EChemDID could be useful to model electrochemical energy conversion devices

An accurate reactive power control study in virtual flux droop control

Science.gov (United States)

Wang, Aimeng; Zhang, Jia

2017-12-01

This paper investigates the problem of reactive power sharing based on virtual flux droop method. Firstly, flux droop control method is derived, where complicated multiple feedback loops and parameter regulation are avoided. Then, the reasons for inaccurate reactive power sharing are theoretically analyzed. Further, a novel reactive power control scheme is proposed which consists of three parts: compensation control, voltage recovery control and flux droop control. Finally, the proposed reactive power control strategy is verified in a simplified microgrid model with two parallel DGs. The simulation results show that the proposed control scheme can achieve accurate reactive power sharing and zero deviation of voltage. Meanwhile, it has some advantages of simple control and excellent dynamic and static performance.

Antiretroviral procurement and supply chain management.

Science.gov (United States)

Ripin, David J; Jamieson, David; Meyers, Amy; Warty, Umesh; Dain, Mary; Khamsi, Cyril

2014-01-01

Procurement, the country-level process of ordering antiretrovirals (ARVs), and supply chain management, the mechanism by which they are delivered to health-care facilities, are critical processes required to move ARVs from manufacturers to patients. To provide a glimpse into the ARV procurement and supply chain, the following pages provide an overview of the primary stakeholders, principal operating models, and policies and regulations involved in ARV procurement. Also presented are key challenges that need to be addressed to ensure that the supply chain is not a barrier to the goal of universal coverage. This article will cover the steps necessary to order and distribute ARVs, including different models of delivery, key stakeholders involved, strategic considerations that vary depending on context and policies affecting them. The single drug examples given illustrate the complications inherent in fragmented supply and demand-driven models of procurement and supply chain management, and suggest tools for navigating these hurdles that will ultimately result in more secure and reliable ARV provision. Understanding the dynamics of ARV supply chain is important for the global health community, both to ensure full and efficient treatment of persons living with HIV as well as to inform the supply chain decisions for other public health products.

Crude oil price dynamics: A study on effects of market expectation and strategic supply on price movements

Science.gov (United States)

Jin, Xin

Recent years have seen dramatic fluctuations in crude oil prices. This dissertation attempts to better understand price behavior. The first chapter studies the behavior of crude oil spot and futures prices. Oil prices, particularly spot and short-term futures prices, appear to have switched from I(0) to I(1) in early 2000s. To better understand this apparent change in persistence, a factor model of oil prices is proposed, where the prices are decomposed into long-term and short-term components. The change in the persistence behavior can be explained by changes in the relative volatility of the underlying components. Fitting the model to weekly data on WTI prices, the volatility of the persistent shocks increased substantially relative to other shocks. In addition, the risk premiums in futures prices have changed their signs and become more volatile. The estimated net marginal convenience yield using the model also shows changes in its behavior. These observations suggest that a dramatic fundamental change occurred in the period from 2002 to 2004 in the dynamics of the crude oil market. The second chapter explores the short-run price-inventory dynamics in the presence of different shocks. Classical competitive storage model states that inventory decision considers both current and future market condition, and thus interacts with spot and expected future spot prices. We study competitive storage holding in an equilibrium framework, focusing on the dynamic response of price and inventory to different shocks. We show that news shock generates response profile different from traditional contemporaneous shocks in price and inventory. The model is applied to world crude oil market, where the market expectation is estimated to experience a sharp change in early 2000s, together with a persisting constrained supply relative to demand. The expectation change has limited effect on crude oil spot price though. The world oil market structure has been studied extensively but no

Early stage oxynitridation process of Si(001) surface by NO gas: Reactive molecular dynamics simulation study

International Nuclear Information System (INIS)

Cao, Haining; Kim, Seungchul; Lee, Kwang-Ryeol; Srivastava, Pooja; Choi, Keunsu

2016-01-01

Initial stage of oxynitridation process of Si substrate is of crucial importance in fabricating the ultrathin gate dielectric layer of high quality in advanced MOSFET devices. The oxynitridation reaction on a relaxed Si(001) surface is investigated via reactive molecular dynamics (MD) simulation. A total of 1120 events of a single nitric oxide (NO) molecule reaction at temperatures ranging from 300 to 1000 K are statistically analyzed. The observed reaction kinetics are consistent with the previous experimental or calculation results, which show the viability of the reactive MD technique to study the NO dissociation reaction on Si. We suggest the reaction pathway for NO dissociation that is characterized by the inter-dimer bridge of a NO molecule as the intermediate state prior to NO dissociation. Although the energy of the inter-dimer bridge is higher than that of the intra-dimer one, our suggestion is supported by the ab initio nudged elastic band calculations showing that the energy barrier for the inter-dimer bridge formation is much lower. The growth mechanism of an ultrathin Si oxynitride layer is also investigated via consecutive NO reactions simulation. The simulation reveals the mechanism of self-limiting reaction at low temperature and the time evolution of the depth profile of N and O atoms depending on the process temperature, which would guide to optimize the oxynitridation process condition.

Early stage oxynitridation process of Si(001) surface by NO gas: Reactive molecular dynamics simulation study

Energy Technology Data Exchange (ETDEWEB)

Cao, Haining; Kim, Seungchul; Lee, Kwang-Ryeol, E-mail: krlee@kist.re.kr [Computational Science Research Center, Korea Institute of Science and Technology, 5, Hwarangno 14-gil, Seongbuk-gu, Seoul 02792 (Korea, Republic of); Department of Nanomaterial Science and Technology, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113 (Korea, Republic of); Srivastava, Pooja; Choi, Keunsu [Computational Science Research Center, Korea Institute of Science and Technology, 5, Hwarangno 14-gil, Seongbuk-gu, Seoul 02792 (Korea, Republic of)

2016-03-28

Initial stage of oxynitridation process of Si substrate is of crucial importance in fabricating the ultrathin gate dielectric layer of high quality in advanced MOSFET devices. The oxynitridation reaction on a relaxed Si(001) surface is investigated via reactive molecular dynamics (MD) simulation. A total of 1120 events of a single nitric oxide (NO) molecule reaction at temperatures ranging from 300 to 1000 K are statistically analyzed. The observed reaction kinetics are consistent with the previous experimental or calculation results, which show the viability of the reactive MD technique to study the NO dissociation reaction on Si. We suggest the reaction pathway for NO dissociation that is characterized by the inter-dimer bridge of a NO molecule as the intermediate state prior to NO dissociation. Although the energy of the inter-dimer bridge is higher than that of the intra-dimer one, our suggestion is supported by the ab initio nudged elastic band calculations showing that the energy barrier for the inter-dimer bridge formation is much lower. The growth mechanism of an ultrathin Si oxynitride layer is also investigated via consecutive NO reactions simulation. The simulation reveals the mechanism of self-limiting reaction at low temperature and the time evolution of the depth profile of N and O atoms depending on the process temperature, which would guide to optimize the oxynitridation process condition.

Operation of SST-1 TF power supply during SST-1 campaigns

International Nuclear Information System (INIS)

Sharma, Dinesh Kumar; Vora, Murtuza M.; Ojha, Amit; Singh, Akhilesh Kumar; Bhavsar, Chirag

2015-01-01

Highlights: • SST-1 TF power supply is 12 pulse SCR converter circuit. • TF power supply protection, measurement and control scheme are explained. • Quench, emergency and normal shot process is explained and results of SST-1 campaigns are shown. • Dynamic control of TF current. • The paper shows the results of last ten SST-1 campaigns. - Abstract: SST-1 TF power supply provides the direct current for the required magnetic field of TF coil. TF power supply includes transformer, 12-pulse converter, bus bar, water-cooled cable, protection and measuring equipments, and isolator, VME DAC system and GUI software. TF power supply is operated through GUI software built in TCL/Tk. VME DAC system monitors the parameters, provides On/Off commands, voltage and current references and initiates predefined reference to emergency shutdown. The emergency shutdown is hardwired to TF power supply from central control. During quench power supply converter opens DCCB and dump resistor is connected in the circuit and VME DAC system acquires bus bar voltage, dump voltage and dump current. Operation of TF power supply also requires monitoring of SCR and transformer temperature and water flow rate of water-cooled cable during high current long pulse shot. Before start up of TF power supply a quench simulation is performed to check the readiness of protection. This paper describes pre startup operation, normal shot operation, emergency and quench process, dynamic control and complete shutdown operation of TF power supply.

Operation of SST-1 TF power supply during SST-1 campaigns

Energy Technology Data Exchange (ETDEWEB)

Sharma, Dinesh Kumar, E-mail: dinesh@ipr.res.in; Vora, Murtuza M.; Ojha, Amit; Singh, Akhilesh Kumar; Bhavsar, Chirag

2015-10-15

Highlights: • SST-1 TF power supply is 12 pulse SCR converter circuit. • TF power supply protection, measurement and control scheme are explained. • Quench, emergency and normal shot process is explained and results of SST-1 campaigns are shown. • Dynamic control of TF current. • The paper shows the results of last ten SST-1 campaigns. - Abstract: SST-1 TF power supply provides the direct current for the required magnetic field of TF coil. TF power supply includes transformer, 12-pulse converter, bus bar, water-cooled cable, protection and measuring equipments, and isolator, VME DAC system and GUI software. TF power supply is operated through GUI software built in TCL/Tk. VME DAC system monitors the parameters, provides On/Off commands, voltage and current references and initiates predefined reference to emergency shutdown. The emergency shutdown is hardwired to TF power supply from central control. During quench power supply converter opens DCCB and dump resistor is connected in the circuit and VME DAC system acquires bus bar voltage, dump voltage and dump current. Operation of TF power supply also requires monitoring of SCR and transformer temperature and water flow rate of water-cooled cable during high current long pulse shot. Before start up of TF power supply a quench simulation is performed to check the readiness of protection. This paper describes pre startup operation, normal shot operation, emergency and quench process, dynamic control and complete shutdown operation of TF power supply.

Optimum Arrangement of Reactive Power Sources While Using Genetic Algori

Directory of Open Access Journals (Sweden)

A. M. Gashimov

2010-01-01

Full Text Available Reduction of total losses in distribution electricity supply network is considered as an important measure which serves for improvement of efficiency of electric power supply systems. This objective can be achieved by optimum distribution of reactive power sources in proper places of distribution electricity supply network. The proposed methodology is based on application of a genetic algorithm. Total expenses for installation of capacitor banks, their operation and also expenses related to electric power losses are considered as an efficiency function which is used for determination of places with optimum values of capacitor bank power. The methodology is the most efficient for selection of optimum places in the network where it is necessary to install capacitor banks with due account of their power control depending on a switched-on load value in the units.

Does reactivation trigger episodic memory change? A meta-analysis.

Science.gov (United States)

Scully, Iiona D; Napper, Lucy E; Hupbach, Almut

2017-07-01

According to the reconsolidation hypothesis, long-term memories return to a plastic state upon their reactivation, leaving them vulnerable to interference effects and requiring re-storage processes or else these memories might be permanently lost. The present study used a meta-analytic approach to critically evaluate the evidence for reactivation-induced changes in human episodic memory. Results indicated that reactivation makes episodic memories susceptible to physiological and behavioral interference. When applied shortly after reactivation, interference manipulations altered the amount of information that could be retrieved from the original learning event. This effect was more pronounced for remote memories and memories of narrative structure. Additionally, new learning following reactivation reliably increased the number of intrusions from new information into the original memory. These findings support a dynamic view of long-term memory by showing that memories can be changed long after they were acquired. Copyright © 2016 Elsevier Inc. All rights reserved.

Haulier Value Creation in Supply Chains

DEFF Research Database (Denmark)

Borgström, Benedikte; Gammelgaard, Britta

2017-01-01

Purpose: Road transport is a dynamic sector with market changes because of liberalization and increasing demand of transport and logistics services. Shippers’ supply chain objectives of low costs and agility and a demanding operating environment due to, for example, congestion is challenging...... understanding of capability deployment. Original/value: This research shows that innovation of transport companies’ (hauliers’ and other types of logistics providers’) value propositions drives competitiveness. The strategy-as-practice approach is applied as the theoretical lens for understanding and developing...... strategic outcomes of transport and logistics provision and supply chain value creation....

Life Support with Failures and Variable Supply

Science.gov (United States)

Jones, Harry

2010-01-01

The life support system for long duration missions will recycle oxygen and water to reduce the material resupply mass from Earth. The impact of life support failures was investigated by dynamic simulation of a lunar outpost habitat life support model. The model was modified to simulate resupply delays, power failures, recycling system failures, and storage failures. Many failures impact the lunar outpost water supply directly or indirectly, depending on the water balance and water storage. Failure effects on the water supply are reduced if Extra Vehicular Activity (EVA) water use is low and the water supply is ample. Additional oxygen can be supplied by scavenging unused propellant or by production from regolith, but the amounts obtained can vary significantly. The requirements for oxygen and water can also vary significantly, especially for EVA. Providing storage buffers can improve efficiency and reliability, and minimize the chance of supply failing to meet demand. Life support failures and supply variations can be survivable if effective solutions are provided by the system design

Dynamic of biogeochemical selenium cycle in terrestrial ecosystems: retention and reactivity in soil; role of vegetation

International Nuclear Information System (INIS)

Di Tullo, Pamela

2015-01-01

This work was performed in the frame of the safety assessment program prior to the possible construction of an underground repository for nuclear waste (HAVL). To consolidate risk assessment models associated to a potential 79 Se biosphere contamination, biogeochemistry of stable selenium was investigated, aiming firstly to highlight the dynamics of Se cycling in a forest ecosystem, in terms of inventories and annual fluxes. Consequently to these first results, which suggest a clay role of soil and its organic pool in the global Se cycle, two studies based on the use of isotopically enriched tracers were further carried out in order to clarify the processes involved in (i) Se retention and reactivity in soils and (ii) incorporation of inorganic Se within organic pool of vegetal biomass. (author) [fr

An Information Theoretic Investigation Of Complex Adaptive Supply Networks With Organizational Topologies

Science.gov (United States)

2016-12-22

for the global pattern. A network view has proven useful in modeling a supply - chain for patterns of interaction. Queuing theory can be used to...phenomena. Second, operations management and supply - chain management lack metrics for evolution and dynamism in supply networks. Third, developing...robust theories in the presence of 14 adaptation is a formidable task. Supply - chain management theory can be built by identifying CAS phenomena and

Dynamic optimization of distribution networks. Closed loop operation results; Dynamische Optimierung der Verteilnetze. Closed loop Betriebsergebnisse

Energy Technology Data Exchange (ETDEWEB)

Ilo, Albana [Siemens AG, Wien (Austria); Schaffer, Walter; Rieder, Thomas [Salzburg Netz GmbH, Salzburg (Austria); Dzafic, Izudin [Siemens AG, Nuernberg (Germany)

2012-07-01

A holistic approach of power system control that includes all voltage levels from highest to low voltage is provided. The power grid is conceived as a supply chain. The medium voltage grid represents the central link. The implemented automatic voltage control and the dynamic operation optimization are based on Distribution System State Estimator (DSSE) and Volt/Var Control (VVC) applications. The last one realizes the dynamic optimization of distribution network combining the reactive power of the decentralized generation, capacitors and voltage set points of on-line tap changers. Application of this method has shown, that by using the dynamic voltage control the grid can be stable operated near the low voltage limit. The conservation voltage reduction can be applied in real time. Furthermore the integration of the decentralized generation is facilitated with minimal costs. Until now in this regard required network expansion can be prevented or delayed. (orig.)

Nutrient uptake dynamics across a gradient of nutrient concentrations and ratios at the landscape scale

Science.gov (United States)

Gibson, Catherine A.; O'Reilly, Catherine M.; Conine, Andrea L.; Lipshutz, Sondra M.

2015-02-01

Understanding interactions between nutrient cycles is essential for recognizing and remediating human impacts on water quality, yet multielemental approaches to studying nutrient cycling in streams are currently rare. Here we utilized a relatively new approach (tracer additions for spiraling curve characterization) to examine uptake dynamics for three essential nutrients across a landscape that varied in absolute and relative nutrient availability. We measured nutrient uptake for soluble reactive phosphorous, ammonium-nitrogen, and nitrate-nitrogen in 16 headwater streams in the Catskill Mountains, New York. Across the landscape, ammonium-nitrogen and soluble reactive phosphorus had shorter uptake lengths and higher uptake velocities than nitrate-nitrogen. Ammonium-nitrogen and soluble reactive phosphorus uptake velocities were tightly correlated, and the slope of the relationship did not differ from one, suggesting strong demand for both nutrients despite the high ambient water column dissolved inorganic nitrogen: soluble reactive phosphorus ratios. Ammonium-nitrogen appeared to be the preferred form of nitrogen despite much higher nitrate-nitrogen concentrations. The uptake rate of nitrate-nitrogen was positively correlated with ambient soluble reactive phosphorus concentration and soluble reactive phosphorus areal uptake rate, suggesting that higher soluble reactive phosphorus concentrations alleviate phosphorus limitation and facilitate nitrate-nitrogen uptake. In addition, these streams retained a large proportion of soluble reactive phosphorus, ammonium-nitrogen, and nitrate-nitrogen supplied by the watershed, demonstrating that these streams are important landscape filters for nutrients. Together, these results (1) indicated phosphorus limitation across the landscape but similarly high demand for ammonium-nitrogen and (2) suggested that nitrate-nitrogen uptake was influenced by variability in soluble reactive phosphorus availability and preference for

Optimization of the raw material supply chain for Philips TL factories

NARCIS (Netherlands)

Rodrigues, Iana Araujo

2009-01-01

The globalization results in more complex and dynamic supply chains. While Asia becomes the first sourcing alternative for many companies, supply chains need to be redesigned in order to reduce costs, improve performance, increase flexibility and expand collaboration among the parties involved. It

The dynamics of herpesvirus reactivations during and after severe drug eruptions: their relation to the clinical phenotype and therapeutic outcome.

Science.gov (United States)

Ishida, T; Kano, Y; Mizukawa, Y; Shiohara, T

2014-06-01

Drug-induced hypersensitivity syndrome/drug rash with eosinophilia and systemic symptoms (DIHS/DRESS) and Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) represent contrasting poles of severe drug eruptions, and sequential reactivations of several herpesviruses have exclusively been demonstrated in the former. No previous studies, however, were extended beyond the acute stage. We sought to investigate whether herpesvirus reactivations could also be observed in SJS/TEN and beyond the acute stage of both diseases. Patients with SJS (n = 16), SJS/TEN overlap (n = 2), TEN (n = 10), and DIHS/DRESS (n = 34) were enrolled. We performed a retrospective analysis of Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and cytomegalovirus (CMV) DNA loads sequentially determined by real-time polymerase chain reaction during a 2-year period after onset. Persistently increased EBV loads were detected in SJS during the acute stage and long after resolution, but not in others. In contrast, high HHV-6 loads were exclusively detected in DIHS/DRESS during the acute stage. The dynamics of herpesvirus reactivation varied in DIHS/DRESS according to the use of systemic corticosteroids: While EBV loads were higher in patients not receiving systemic corticosteroids, CMV and HHV-6 loads were higher in those receiving them. Distinct patterns of herpesvirus reactivation according to the pathological phenotype and to the use of systemic corticosteroids were observed during the acute stage and follow-up period, which may contribute, at least in part, to the difference in the clinical manifestations and long-term outcomes. Systemic corticosteroids during the acute stage may improve the outcomes in DIHS/DRESS. © 2014 The Authors. Allergy Published by John Wiley & Sons Ltd.

Supply network configuration—A benchmarking problem

Science.gov (United States)

Brandenburg, Marcus

2018-03-01

Managing supply networks is a highly relevant task that strongly influences the competitiveness of firms from various industries. Designing supply networks is a strategic process that considerably affects the structure of the whole network. In contrast, supply networks for new products are configured without major adaptations of the existing structure, but the network has to be configured before the new product is actually launched in the marketplace. Due to dynamics and uncertainties, the resulting planning problem is highly complex. However, formal models and solution approaches that support supply network configuration decisions for new products are scant. The paper at hand aims at stimulating related model-based research. To formulate mathematical models and solution procedures, a benchmarking problem is introduced which is derived from a case study of a cosmetics manufacturer. Tasks, objectives, and constraints of the problem are described in great detail and numerical values and ranges of all problem parameters are given. In addition, several directions for future research are suggested.

Multi-perspective analysis of China's energy supply security

International Nuclear Information System (INIS)

Geng, Jiang-Bo; Ji, Qiang

2014-01-01

China's energy supply security has faced many challenges such as the drastic change of the international energy environment and the domestic energy situation and so on. This paper constructs a multi-dimensional indicator system for the main risks deriving from four aspects to evaluate the situation of China's energy supply security and analyze its evolution characteristics from 1994 to 2011. The results indicate that the situation of China's energy supply security generally presented a downtrend during 1994–2008, as a result of increasing international energy market monopoly and high volatility of international crude oil prices. After 2008, the overall level of China's energy supply security has improved to the level of 2003, which is attributed to the relatively stable international energy environment as well as the effective implementation of energy policies. - Highlights: • A multi-dimensional index system for energy supply security is constructed. • The dynamic influences of external and internal risks are analyzed. • China's energy supply security presents a downward trend during 1994–2008. • The level of China's energy supply security has improved since 2009

A REVIEW: POTENSI RISIKO PADA SUPPLY CHAIN RISK MANAGEMENT

Directory of Open Access Journals (Sweden)

Dwi Iryaning Handayani

2016-04-01

Full Text Available Supply Chain Risk Management merupakan risiko yang terjadi pada aliran produk, informasi, bahan baku sampai pengiriman produk akhir yang mengancam keseluruhan supply chain dari pemasok awal hingga sampai konsumen. Sedangkan Supply chain disruptions (gangguan rantai pasok adalah peristiwa tak terencana yang terjadi dalam rantai pasok yang bisa mempengaruhi aliran bahan dan komponen. Kejadian risiko yang terjadi didalam supply chain telah banyak dilakukan oleh beberapa peneliti sehingga perlu dilakukan review untuk mengetahui potensi risiko yang terjadi pada supply chain. Risiko yang terjadi pada supply chain berdasarkan hasil penelitian sebelumya terdapat 120 jenis risiko. Kesamaan risiko yang terjadi pada supply chain menghasilkan 17 jenis risiko yang sama pada supply chain dan terdapat 3 risiko yang sering terjadi yaitu risiko demand, keterlambatan bahan baku, Bencana alam (discruption, sedangkan 14 risiko lainnya yaitu , kwalitas supplier, kwalitas produk, sistem informasi, harga, suplai, produk rusak digudang, finansial, ketergantungan supplier, penundaan, kapasitas produksi, persediaan, kekurangan bahan baku, selisih stok dan politik. Adapun mitigasi yang dapat dilakukan dalam mengatasi gangguan supply chain ada 9 strategi yaitu: postponement, strategy stock, flexible supply base. make and buy, economic supply incentives, flexible transportation. revenue management via dynamic pricing and promotion, assortment planning. silent product rollover.

The System Dynamics Model in Electronic Products Closed-Loop Supply Chain Distribution Network with Three-Way Recovery and the Old-for-New Policy

Directory of Open Access Journals (Sweden)

Xiao-qing Zhang

2016-01-01

Full Text Available With the technological developments and rapid changes in demand pattern, diverse varieties of electronic products are entering into the market with reduced lifecycle which leads to the environmental problems. The awareness of electronic products take-back and recovery has been increasing in electronic products supply chains. In this paper, we build a system dynamics model for electronic products closed-loop supply chain distribution network with the old-for-new policy and three electronic products recovery ways, namely, electronic products remanufacturing, electronic component reuse and remanufacturing, and electronic raw material recovery. In the simulation study, we investigate the significance of various factors including the old-for-new policy, collection and remanufacturing, their interactions and the type of their impact on bullwhip, and profitability through sensitivity analysis. Our results instruct that the old-for-new policy and three electronic products recovery ways can reduce the bullwhip effect in the retailers and the distributors and increases the profitability in the closed-loop supply chain distribution network.

Integrating Stable Isotope - Reactive Transport Model Approach for Assessment of Chlorinated Solvent Degradation

Science.gov (United States)

2016-06-01

aerobic cometabolism, reductive dechlorination evidence was reported from the toe of the plume, where TCE enters the Lower Lithologic Unit. The CSM of the...modeling in reactive transport: 50 years of artificial recharge in the Amsterdam Water Supply Dunes . J. Hydrology 454: 7-25. Khan, F. I., et al

A SURVEY OF STACKELBERG DIFFERENTIAL GAME MODELS IN SUPPLY AND MARKETING CHANNELS

Institute of Scientific and Technical Information of China (English)

Xiuli HE; Ashutosh PRASAD; Suresh P. SETHI; Genaro J. GUTIERREZ

2007-01-01

Stackelberg differential game models have been used to study sequential decision making in noncooperative games in diverse fields. In this paper, we survey recent applications of Stackelberg differential game models to the supply chain management and marketing channels literatures. A common feature of these applications is the specification of the game structure: a decentralized channel composed of a manufacturer and independent retailers, and a sequential decision procedure with demand and supply dynamics and coordination issues. In supply chain management, Stackelberg differential games have been used to investigate inventory issues, wholesale and retail pricing strategies, and outsourcing in dynamic environments. The underlying demand typically has growth dynamics or seasonal variation. In marketing, Stackelberg differential games have been used to model cooperative advertising programs, store brand and national brand advertising strategies, shelf space allocation, and pricing and advertising decisions. The demand dynamics are usually extensions of the classical advertising capital models or sales-advertising response models. We begin by explaining the Stackelberg differential game solution methodology and then provide a description of the models and results reported in the literature.

The Impact of Green Supply Chain Management on Transportation Cost Reduction in Turkey

Directory of Open Access Journals (Sweden)

Mehmet SARIDOGAN

2012-01-01

Full Text Available Supply chain management (SCM has become an important competitive approach for organizations. The issue of green supply chain management is critical for the successful implementation of industrial ecosystems and industrial ecology. Organizations have a number of reasons for implementing these green supply chain policies, from reactive regulatory reasons, to proactive strategic and competitive advantage reasons. From an overall environmental and organizational perspective, it is important to understand the situation and what issues exist in this field. Many organizations worldwide have already experienced globalization and a shifting focus to competition among networks of companies in this environment. Multinational enterprises have established global networks of suppliers that take advantage of country-industry specific characteristics to build this competitive advantage. To success having this competitive advantage, logistics and supply chain managers have to balance efforts to reduce costs and innovate while maintaining good environmental (ecological performance (Pagell et al., 2004. Therefore, today, competition is not between companies, between supply chains. This study brings us the effect of Green Supply Chain Management (GSCM on the Transportation Cost Reduction (TCR.

Consistent nutrient storage and supply mediated by diverse fish communities in coral reef ecosystems.

Science.gov (United States)

Allgeier, Jacob E; Layman, Craig A; Mumby, Peter J; Rosemond, Amy D

2014-08-01

Corals thrive in low nutrient environments and the conservation of these globally imperiled ecosystems is largely dependent on mitigating the effects of anthropogenic nutrient enrichment. However, to better understand the implications of anthropogenic nutrients requires a heightened understanding of baseline nutrient dynamics within these ecosystems. Here, we provide a novel perspective on coral reef nutrient dynamics by examining the role of fish communities in the supply and storage of nitrogen (N) and phosphorus (P). We quantified fish-mediated nutrient storage and supply for 144 species and modeled these data onto 172 fish communities (71 729 individual fish), in four types of coral reefs, as well as seagrass and mangrove ecosystems, throughout the Northern Antilles. Fish communities supplied and stored large quantities of nutrients, with rates varying among ecosystem types. The size structure and diversity of the fish communities best predicted N and P supply and storage and N : P supply, suggesting that alterations to fish communities (e.g., overfishing) will have important implications for nutrient dynamics in these systems. The stoichiometric ratio (N : P) for storage in fish mass (~8 : 1) and supply (~20 : 1) was notably consistent across the four coral reef types (but not seagrass or mangrove ecosystems). Published nutrient enrichment studies on corals show that deviations from this N : P supply ratio may be associated with poor coral fitness, providing qualitative support for the hypothesis that corals and their symbionts may be adapted to specific ratios of nutrient supply. Consumer nutrient stoichiometry provides a baseline from which to better understand nutrient dynamics in coral reef and other coastal ecosystems, information that is greatly needed if we are to implement more effective measures to ensure the future health of the world's oceans. © 2014 John Wiley & Sons Ltd.

Adaptive tactical pricing in multi-agent supply chain markets using economic regimes

NARCIS (Netherlands)

Hogenboom, A.; Ketter, W.; Dalen, van Jan; Kaymak, U.; Collins, J.; Gupta, A.

In today's complex and dynamic supply chain markets, information systems are essential for effective supply chain management. Complex decision making processes on strategic, tactical, and operational levels require substantial timely support in order to contribute to organizations' agility.

Secure provision of reactive power ancillary services in competitive electricity markets

Science.gov (United States)

El-Samahy, Ismael

The research work presented in this thesis discusses various complex issues associated with reactive power management and pricing in the context of new operating paradigms in deregulated power systems, proposing appropriate policy solutions. An integrated two-level framework for reactive power management is set forth, which is both suitable for a competitive market and ensures a secure and reliable operation of the associated power system. The framework is generic in nature and can be adopted for any electricity market structure. The proposed hierarchical reactive power market structure comprises two stages: procurement of reactive power resources on a seasonal basis, and real-time reactive power dispatch. The main objective of the proposed framework is to provide appropriate reactive power support from service providers at least cost, while ensuring a secure operation of the power system. The proposed procurement procedure is based on a two-step optimization model. First, the marginal benefits of reactive power supply from each provider, with respect to system security, are obtained by solving a loadability-maximization problem subject to transmission security constraints imposed by voltage and thermal limits. Second, the selected set of generators is determined by solving an optimal power flow (OPF)-based auction. This auction maximizes a societal advantage function comprising generators' offers and their corresponding marginal benefits with respect to system security, and considering all transmission system constraints. The proposed procedure yields the selected set of generators and zonal price components, which would form the basis for seasonal contracts between the system operator and the selected reactive power service providers. The main objective of the proposed reactive power dispatch model is to minimize the total payment burden on the Independent System Operator (ISO), which is associated with reactive power dispatch. The real power generation is

Fast Flux Test Facility (FFTF) feedback reactivity components

International Nuclear Information System (INIS)

Nguyen, D.H.

1988-04-01

The static tests conducted during Cycle 8A (1986) of the FFTF have allowed, for the first time, the experimental determination of each of the feedback reactivities caused by the following mechanisms: fuel axial expansion, control rod repositioning, core radial expansion, and subassembly bowing. A semiempirical equation was obtained to describe each of these feedback components that depended only on the relevant reactor temperature (bowing was presented in a tabular form). The Doppler and sodium density reactivities were calculated using existing mechanistic methods. Although they could also be fitted with closed-form equations depending only on temperatures, these equations are not needed in transient analyses using whole core safety computer codes, which use mechanistic methods. The static feedback reactivity model was extended to obtain a dynamic model via the concept of ''time constants.'' Besides being used for transient analyses in the FFTF, these feedback equations constitute a database for the validation and/or calibration of mechanistic feedback reactivity models. 2 refs., 6 tabs

Hybrid modeling and empirical analysis of automobile supply chain network

Science.gov (United States)

Sun, Jun-yan; Tang, Jian-ming; Fu, Wei-ping; Wu, Bing-ying

2017-05-01

Based on the connection mechanism of nodes which automatically select upstream and downstream agents, a simulation model for dynamic evolutionary process of consumer-driven automobile supply chain is established by integrating ABM and discrete modeling in the GIS-based map. Firstly, the rationality is proved by analyzing the consistency of sales and changes in various agent parameters between the simulation model and a real automobile supply chain. Second, through complex network theory, hierarchical structures of the model and relationships of networks at different levels are analyzed to calculate various characteristic parameters such as mean distance, mean clustering coefficients, and degree distributions. By doing so, it verifies that the model is a typical scale-free network and small-world network. Finally, the motion law of this model is analyzed from the perspective of complex self-adaptive systems. The chaotic state of the simulation system is verified, which suggests that this system has typical nonlinear characteristics. This model not only macroscopically illustrates the dynamic evolution of complex networks of automobile supply chain but also microcosmically reflects the business process of each agent. Moreover, the model construction and simulation of the system by means of combining CAS theory and complex networks supplies a novel method for supply chain analysis, as well as theory bases and experience for supply chain analysis of auto companies.

A structurally driven analysis of thiol reactivity in mammalian albumins.

Science.gov (United States)

Spiga, Ottavia; Summa, Domenico; Cirri, Simone; Bernini, Andrea; Venditti, Vincenzo; De Chiara, Matteo; Priora, Raffaella; Frosali, Simona; Margaritis, Antonios; Di Giuseppe, Danila; Di Simplicio, Paolo; Niccolai, Neri

2011-04-01

Understanding the structural basis of protein redox activity is still an open question. Hence, by using a structural genomics approach, different albumins have been chosen to correlate protein structural features with the corresponding reaction rates of thiol exchange between albumin and disulfide DTNB. Predicted structures of rat, porcine, and bovine albumins have been compared with the experimentally derived human albumin. High structural similarity among these four albumins can be observed, in spite of their markedly different reactivity with DTNB. Sequence alignments offered preliminary hints on the contributions of sequence-specific local environments modulating albumin reactivity. Molecular dynamics simulations performed on experimental and predicted albumin structures reveal that thiolation rates are influenced by hydrogen bonding pattern and stability of the acceptor C34 sulphur atom with donor groups of nearby residues. Atom depth evolution of albumin C34 thiol groups has been monitored during Molecular Dynamic trajectories. The most reactive albumins appeared also the ones presenting the C34 sulphur atom on the protein surface with the highest accessibility. High C34 sulphur atom reactivity in rat and porcine albumins seems to be determined by the presence of additional positively charged amino acid residues favoring both the C34 S⁻ form and the approach of DTNB. Copyright © 2011 Wiley Periodicals, Inc.

Supply Chain Management: from Linear Interactions to Networked Processes

Directory of Open Access Journals (Sweden)

Doina FOTACHE

2006-01-01

Full Text Available Supply Chain Management is a distinctive product, with a tremendous impact on the software applications market. SCM applications are back-end solutions intended to link suppliers, manufacturers, distributors and resellers in a production and distribution network, which allows the enterprise to track and consolidate the flows of materials and data trough the process of manufacturing and distribution of goods/services. The advent of the Web as a major means of conducting business transactions and business-tobusiness communications, coupled with evolving web-based supply chain management (SCM technology, has resulted in a transition period from “linear” supply chain models to "networked" supply chain models. The technologies to enable dynamic process changes and real time interactions between extended supply chain partners are emerging and being deployed at an accelerated pace.

Overview of MPC applications in supply chains: Potential use and benefits in the management of forest-based supply chains

Directory of Open Access Journals (Sweden)

Tatiana M. Pinho

2015-12-01

Full Text Available Aim of study: This work aims to provide an overview of Model Predictive Controllers (MPC applications in supply chains, to describe the forest-based supply chain and to analyse the potential use and benefits of MPC in a case study concerning a biomass supply chain.Area of study: The proposed methods are being applied to a company located in Finland.Material and methods: Supply chains are complex systems where actions and partners’ coordination influence the whole system performance. The increase of competitiveness and need of quick responses to the costumers implies the use of efficient management techniques. The control theory, particularly MPC, has been successfully used as a supply chain management tool. MPC is able to deal with dynamic interactions between the partners and to globally optimize the supply chain performance in the presence of disturbances. However, as far as is authors’ knowledge, there are no applications of this methodology in the forest-based supply chains. This work proposes a control architecture to improve the performance of the forest supply chain. The controller is based on prediction models which are able to simulate the system and deal with disturbances.Main results: The preliminary results enable to evaluate the impacts of disturbances in the supply chain. Thus, it is possible to react beforehand, controlling the schedules and tasks’ allocation, or alert the planning level in order to generate a new plan.Research highlights:   Overview of MPC applications in supply chains; forest-based supply chain description; case study presentation: wood biomass supply chain for energy production; MPC architecture proposal to decrease the operation times.Keywords: biomass; forest; Model Predictive Control; planning; supply chain.

A ReaxFF-based molecular dynamics study of the mechanisms of interactions between reactive oxygen plasma species and the Candida albicans cell wall

Science.gov (United States)

Zhao, T.; Shi, L.; Zhang, Y. T.; Zou, L.; Zhang, L.

2017-10-01

Atmospheric pressure non-equilibrium plasmas have attracted significant attention and have been widely used to inactivate pathogens, yet the mechanisms underlying the interactions between plasma-generated species and bio-organisms have not been elucidated clearly. In this paper, reactive molecular dynamics simulations are employed to investigate the mechanisms of interactions between reactive oxygen plasma species (O, OH, and O2) and β-1,6-glucan (a model for the C. albicans cell wall) from a microscopic point of view. Our simulations show that O and OH species can break structurally important C-C and C-O bonds, while O2 molecules exhibit only weak, non-bonded interactions with β-1,6-glucan. Hydrogen abstraction from hydroxyl or CH groups occurs first in all bond cleavage mechanisms. This is followed by a cascade of bond cleavage and double bond formation events. These lead to the destruction of the fungal cell wall. O and OH have similar effects related to their bond cleavage mechanisms. Our simulation results provide fundamental insights into the mechanisms underlying the interactions between reactive oxygen plasma species and the fungal cell wall of C. albicans at the atomic level.

The dynamic relation between management control and governance structure in a supply chain context

NARCIS (Netherlands)

Veen, van P.M.G.; Verdaasdonk, P.J.A.

2009-01-01

Purpose – The purpose of this paper is to show that local management control systems within supply chain organisations and the governance of supply chains are intertwined and that local control systems and governance structure have an important effect on the functioning of the supply chain.

Policy design in closed-loop supply chains for the integrated management of component recycling and spare parts supply in the electronics industry

Science.gov (United States)

Schroeter, Marcus; Spengler, Thomas

2004-02-01

The strategy to recover components from discarded electrical and electronic equipment to obtain spare parts is promising, especially during the final service phase. In that phase, the original product is no longer produced and the sources of new parts are often limited. Controlling those closed-loop supply chains is challenging. Decision makers have to choose when to acquire discarded equipment, when to recover used parts, and when to produce new parts. We developed a generic system dynamics model that provides a test for various proposed policies to control closed-loop supply chains with parts recovery and spare-parts supply.

Determination of static and dynamic reactivity effects in KNK II

International Nuclear Information System (INIS)

Essig, C.

1987-11-01

In the frame of a pre-study of the KNK II test program two series of experiments related to inherent safety characteristics of sodium cooled breeder reactors have been elaborated, which are one basis for the performance of experiments of the Loss Of Flow (LOF) type and the Loss Of Heat Sink (LOHS) type. Tests of this type at KNK II would -different from the earlier tests at RAPSODIE and EBR-II- provide a demonstration of the inherently safe performance in case of a significantly non-zero Doppler effect. With a suitable execution, the foreseen series of experiments allow, as explained in this report, a substantial separation of the reactivity contributions and the determination of reactivity effects, i.e. the time constants of the recouplings. The performance and evaluation of these experiments with respect to the inherent safety potential will once more underline the distinguished role of KNK II for the development of fast breeders [de

System Dynamics of Polysilicon for Solar Photovoltaics: A Framework for Investigating the Energy Security of Renewable Energy Supply Chains

Directory of Open Access Journals (Sweden)

Debra Sandor

2018-01-01

Full Text Available Renewable energy, produced with widely available low-cost energy resources, is often included as a component of national strategies to address energy security and sustainability. Market and political forces cannot disrupt the sun or wind, unlike oil and gas supplies. However, the cost of renewable energy is highly dependent on technologies manufactured through global supply chains in leading manufacturing countries. The countries that contribute to the global supply chains may take actions that, directly or indirectly, influence global access to materials and components. For example, high-purity polysilicon, a key material in solar photovoltaics, has experienced significant price fluctuations, affecting the manufacturing capacity and cost of both polysilicon and solar panels. This study developed and validated an initial system dynamics framework to gain insights into global trade in polysilicon. The model represents an initial framework for exploration. Three regions were modeled—China, the United States, and the rest of the world—for a range of trade scenarios to understand the impacts of import duties and non-price drivers on the relative volumes of imports and domestic supply. The model was validated with the historical case of China imposing an import duty on polysilicon from the United States, the European Union, and South Korea, which altered the regional flows of polysilicon—in terms of imports, exports, and domestic production—to varying degrees. As expected, the model tracked how regional demand shares and influx volumes decrease as a duty on a region increases. Using 2016 as a reference point, in the scenarios examined for U.S. exports to China, each 10% increase in the import duty results in a 40% decrease in import volume. The model also indicates that, under the scenarios investigated, once a duty has been imposed on a region, the demand share from that region declines and does not achieve pre-duty levels, even as global

Photoisomerization and photodissociation dynamics of reactive free radicals

Energy Technology Data Exchange (ETDEWEB)

Bise, Ryan T. [Univ. of California, Berkeley, CA (United States)

2000-08-01

The photofragmentation pathways of chemically reactive free radicals have been examined using the technique of fast beam photofragment translational spectroscopy. Measurements of the photodissociation cross-sections, product branching ratios, product state energy distributions, and angular distributions provide insight into the excited state potential energy surfaces and nonadiabatic processes involved in the dissociation mechanisms. Photodissociation spectroscopy and dynamics of the predissociative $\\tilde{A}$²A₁ and $\\tilde{B}$²A₂ states of CH₃S have been investigated. At all photon energies, CH₃ + S(³P_j), was the main reaction channel. The translational energy distributions reveal resolved structure corresponding to vibrational excitation of the CH₃ umbrella mode and the S(³P_j) fine-structure distribution from which the nature of the coupled repulsive surfaces is inferred. Dissociation rates are deduced from the photofragment angular distributions, which depend intimately on the degree of vibrational excitation in the C-S stretch. Nitrogen combustion radicals, NCN, CNN and HNCN have also been studied. For all three radicals, the elimination of molecular nitrogen is the primary reaction channel. Excitation to linear excited triplet and singlet electronic states of the NCN radical generates resolved vibrational structure of the N₂ photofragment. The relatively low fragment rotational excitation suggests dissociation via a symmetric C_2V transition state. Resolved vibrational structure of the N₂ photofragment is also observed in the photodissociation of the HNCN radical. The fragment vibrational and rotational distributions broaden with increased excitation energy. Simple dissociation models suggest that the HNCN radical isomerizes to a cyclic intermediate (c-HCNN) which then dissociates via a tight cyclic

Effect of nonlinear void reactivity on bifurcation characteristics of a lumped-parameter model of a BWR: A study relevant to RBMK

Energy Technology Data Exchange (ETDEWEB)

Verma, Dinkar, E-mail: dinkar@iitk.ac.in [Nuclear Engineering and Technology Program, Indian Institute of Technology Kanpur, Kanpur 208 016 (India); Kalra, Manjeet Singh, E-mail: drmanjeet.singh@dituniversity.edu.in [DIT University, Dehradun 248 009 (India); Wahi, Pankaj, E-mail: wahi@iitk.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

2017-04-15

Highlights: • A simplified model with nonlinear void reactivity feedback is studied. • Method of multiple scales for nonlinear analysis and oscillation characteristics. • Second order void reactivity dominates in determining system dynamics. • Opposing signs of linear and quadratic void reactivity enhances global safety. - Abstract: In the present work, the effect of nonlinear void reactivity on the dynamics of a simplified lumped-parameter model for a boiling water reactor (BWR) is investigated. A mathematical model of five differential equations comprising of neutronics and thermal-hydraulics encompassing the nonlinearities associated with both the reactivity feedbacks and the heat transfer process has been used. To this end, we have considered parameters relevant to RBMK for which the void reactivity is known to be nonlinear. A nonlinear analysis of the model exploiting the method of multiple time scales (MMTS) predicts the occurrence of the two types of Hopf bifurcation, namely subcritical and supercritical, leading to the evolution of limit cycles for a range of parameters. Numerical simulations have been performed to verify the analytical results obtained by MMTS. The study shows that the nonlinear reactivity has a significant influence on the system dynamics. A parametric study with varying nominal reactor power and operating conditions in coolant channel has also been performed which shows the effect of change in concerned parameter on the boundary between regions of sub- and super-critical Hopf bifurcations in the space constituted by the two coefficients of reactivities viz. the void and the Doppler coefficient of reactivities. In particular, we find that introduction of a negative quadratic term in the void reactivity feedback significantly increases the supercritical region and dominates in determining the system dynamics.

Retailer’s Procurement Strategy under Endogenous Supply Stability

Directory of Open Access Journals (Sweden)

Chengxiao Feng

2017-12-01

Full Text Available In this paper, a dynamic model is presented to study retailer’s procurement strategy when supply stability is endogenously determined. The optimal supply stability as well as the optimal purchasing strategy are characterized with a quadratic cost function. Based on these models, the following findings are brought about. Firstly, when the difficulty level of building supply stability exceeds a certain threshold, it would be more profitable for the retailer to choose a less reliable supplier. Secondly, given that the suppliers can get positive profit, the retailer would choose the one who has the strongest ability to be reliable. Thirdly, the equilibrium supply to the retailer would always meet the demand on the retailing market. Finally, emergency procurement is shown to be an effective way to reduce the risk of supply chain disruptions. To better fit the real situations, an extended model which considers the impact of the stability on costs is further discussed.

Dual Rate Adaptive Control for an Industrial Heat Supply Process Using Signal Compensation Approach

Energy Technology Data Exchange (ETDEWEB)

Chai, Tianyou; Jia, Yao; Wang, Hong; Su, Chun-Yi

2017-07-09

The industrial heat supply process (HSP) is a highly nonlinear cascaded process which uses a steam valve opening as its control input, the steam flow-rate as its inner loop output and the supply water temperature as its outer loop output. The relationship between the heat exchange rate and the model parameters, such as steam density, entropy, and fouling correction factor and heat exchange efficiency are unknown and nonlinear. Moreover, these model parameters vary in line with steam pressure, ambient temperature and the residuals caused by the quality variations of the circulation water. When the steam pressure and the ambient temperature are of high values and are subjected to frequent external random disturbances, the supply water temperature and the steam flow-rate would interact with each other and fluctuate a lot. This is also true when the process exhibits unknown characteristic variations of the process dynamics caused by the unexpected changes of the heat exchange residuals. As a result, it is difficult to control the supply water temperature and the rates of changes of steam flow-rate well inside their targeted ranges. In this paper, a novel compensation signal based dual rate adaptive controller is developed by representing the unknown variations of dynamics as unmodeled dynamics. In the proposed controller design, such a compensation signal is constructed and added onto the control signal obtained from the linear deterministic model based feedback control design. Such a compensation signal aims at eliminating the unmodeled dynamics and the rate of changes of the currently sample unmodeled dynamics. A successful industrial application is carried out, where it has been shown that both the supply water temperature and the rate of the changes of the steam flow-rate can be controlled well inside their targeted ranges when the process is subjected to unknown variations of its dynamics.

[The development of hospital medical supplies information management system].

Science.gov (United States)

Cao, Shaoping; Gu, Hongqing; Zhang, Peng; Wang, Qiang

2010-05-01

The information management of medical materials by using high-tech computer, in order to improve the efficiency of the consumption of medical supplies, hospital supplies and develop a new technology way to manage the hospital and material support. Using C # NET, JAVA techniques to develop procedures for the establishment of hospital material management information system, set the various management modules, production of various statistical reports, standard operating procedures. The system is convenient, functional and strong, fluent statistical functions. It can always fully grasp and understand the whole hospital supplies run dynamic information, as a modern and effective tool for hospital materials management.

Guidelines for Distribution System Operators on Reactive Power Provision by Electric Vehicles in Low Voltage Grids

DEFF Research Database (Denmark)

Zecchino, Antonio; Marinelli, Mattia; Træholt, Chresten

2017-01-01

The increasing success of electric vehicles is bringing new technical challenges to power system operators. This work intends to provide guidelines for distribution system operators in terms of reactive power requirements when evaluating and authorizing electric vehicles supply equipment with fast...... the amount of reactive power that an individual electric vehicle is expected to provide when connected to a low voltage feeder, in order to benefit of the desired voltage rise effect in comparison to the case of unitary power factor....

Decision support for contemporary purchasing

NARCIS (Netherlands)

Stekelenborg, van R.H.A.; Boer, de L.; Cox, A.; Lamming, R.

1996-01-01

The new business environment has confronted purchasing with an increasingly dynamic and un-predictable environment. While purchasing fonnerly could afford to be reactive to changes in demand specifications, supply markets and supply performance results, the new business environment requires

Analysis of the Dynamic Performance of Self-Excited Induction Generators Employed in Renewable Energy Generation

Directory of Open Access Journals (Sweden)

Mohamed E. A. Farrag

2014-01-01

Full Text Available Incentives, such as the Feed-in-tariff are expected to lead to continuous increase in the deployment of Small Scale Embedded Generation (SSEG in the distribution network. Self-Excited Induction Generators (SEIG represent a significant segment of potential SSEG. The quality of SEIG output voltage magnitude and frequency is investigated in this paper to support the SEIG operation for different network operating conditions. The dynamic behaviour of the SEIG resulting from disconnection, reconnection from/to the grid and potential operation in islanding mode is studied in detail. The local load and reactive power supply are the key factors that determine the SEIG performance, as they have significant influence on the voltage and frequency change after disconnection from the grid. Hence, the aim of this work is to identify the optimum combination of the reactive power supply (essential for self excitation of the SEIG and the active load (essential for balancing power generation and demand. This is required in order to support the SEIG operation after disconnection from the grid, during islanding and reconnection to the grid. The results show that the generator voltage and speed (frequency can be controlled and maintained within the statuary limits. This will enable safe disconnection and reconnection of the SEIG from/to the grid and makes it easier to operate in islanding mode.

Hybridized reactive iron-containing nano-materials for water purification

DEFF Research Database (Denmark)

Mines, Paul D.

Groundwater is an important source for drinking water in all corners of the globe, and in places like Denmark, it is the primary source for drinking water. Climate change and population growth will only lead to further dependence on groundwater as the supply for drinking water. However...... the applicability of nZVI is paramount to its future success as a remediation technique. This PhD project has investigated various materials aimed at solving the reactivity loss of reactive iron to create a robust treatment system capable of treating polluted waters. This PhD project also investigated and developed......, the expanding population and industrialization of human civilization also leads to environmental consequences affecting groundwater sources. Storm-water and agricultural runoff, industrial spillage and dumping, acid mine drainage, and leakage from landfills are a few prime examples of routes of contamination...

The current and perspective problems of nuclear power fuel supply

International Nuclear Information System (INIS)

Solonin, M.I.; Konovalov, I.I.

2003-01-01

Conception of fuel supply is comprised of supplying of natural uranium resources, nuclear fuel production including engineering stages of refining, enriching, production, use of secondary uranium and plutonium raw materials. The structure of nuclear fuel cycle is considered. Enterprises of the Russian nuclear fuel cycle, world recourses and fundamental producers of uranium are performed, demands in natural uranium of Russian and frontier NPP to 2010 are demonstrated. Dynamics of the development of separate methods - diffusion and centrifugal is presented as well as parameters of fuel supply at Russian and frontier NPP are compared [ru

How does network design constrain optimal operation of intermittent water supply?

Science.gov (United States)

Lieb, Anna; Wilkening, Jon; Rycroft, Chris

2015-11-01

Urban water distribution systems do not always supply water continuously or reliably. As pipes fill and empty, pressure transients may contribute to degraded infrastructure and poor water quality. To help understand and manage this undesirable side effect of intermittent water supply--a phenomenon affecting hundreds of millions of people in cities around the world--we study the relative contributions of fixed versus dynamic properties of the network. Using a dynamical model of unsteady transition pipe flow, we study how different elements of network design, such as network geometry, pipe material, and pipe slope, contribute to undesirable pressure transients. Using an optimization framework, we then investigate to what extent network operation decisions such as supply timing and inflow rate may mitigate these effects. We characterize some aspects of network design that make them more or less amenable to operational optimization.

Customer-Driven Supply Chains From Glass Pipelines to Open Innovation Networks

CERN Document Server

Lyons, Andrew C; Piller, Frank; Poler, Raúl

2012-01-01

In recent years, the supply chain has become a key element to the survival and prosperity of organisations in different industry sectors. Organisations dealing in dynamic business environments demand supply chains that support the satisfaction of customer needs. The principles of lean thinking that once permeated standalone organisations have now been transferred to the supply chain, making imperative the development of innovative approaches to supply chain management.    Customer-Driven Supply Chains: From Glass Pipelines to Open Innovation Networks reviews the concept of lean thinking and its relationship to other key initiatives associated with supply chain management. Detailed industrial case studies based on the authors’ experience illustrate the principles behind lean supply chains. Moreover, a series of diagrams are used to illustrate critical concepts and supply chain architectures. Special emphasis is placed on the importance of transferring lean principles from the organisational level to the s...

Hot spot formation and chemical reaction initiation in shocked HMX crystals with nanovoids: a large-scale reactive molecular dynamics study.

Science.gov (United States)

Zhou, Tingting; Lou, Jianfeng; Zhang, Yangeng; Song, Huajie; Huang, Fenglei

2016-07-14

We report million-atom reactive molecular dynamic simulations of shock initiation of β-cyclotetramethylene tetranitramine (β-HMX) single crystals containing nanometer-scale spherical voids. Shock induced void collapse and subsequent hot spot formation as well as chemical reaction initiation are observed which depend on the void size and impact strength. For an impact velocity of 1 km s(-1) and a void radius of 4 nm, the void collapse process includes three stages; the dominant mechanism is the convergence of upstream molecules toward the centerline and the downstream surface of the void forming flowing molecules. Hot spot formation also undergoes three stages, and the principal mechanism is kinetic energy transforming to thermal energy due to the collision of flowing molecules on the downstream surface. The high temperature of the hot spot initiates a local chemical reaction, and the breakage of the N-NO2 bond plays the key role in the initial reaction mechanism. The impact strength and void size have noticeable effects on the shock dynamical process, resulting in a variation of the predominant mechanisms leading to void collapse and hot spot formation. Larger voids or stronger shocks result in more intense hot spots and, thus, more violent chemical reactions, promoting more reaction channels and generating more reaction products in a shorter duration. The reaction products are mainly concentrated in the developed hot spot, indicating that the chemical reactivity of the hmx crystal is greatly enhanced by void collapse. The detailed information derived from this study can aid a thorough understanding of the role of void collapse in hot spot formation and the chemical reaction initiation of explosives.

Emergency material allocation with time-varying supply-demand based on dynamic optimization method for river chemical spills.

Science.gov (United States)

Liu, Jie; Guo, Liang; Jiang, Jiping; Jiang, Dexun; Wang, Peng

2018-04-13

Aiming to minimize the damage caused by river chemical spills, efficient emergency material allocation is critical for an actual emergency rescue decision-making in a quick response. In this study, an emergency material allocation framework based on time-varying supply-demand constraint is developed to allocate emergency material, minimize the emergency response time, and satisfy the dynamic emergency material requirements in post-accident phases dealing with river chemical spills. In this study, the theoretically critical emergency response time is firstly obtained for the emergency material allocation system to select a series of appropriate emergency material warehouses as potential supportive centers. Then, an enumeration method is applied to identify the practically critical emergency response time, the optimum emergency material allocation and replenishment scheme. Finally, the developed framework is applied to a computational experiment based on south-to-north water transfer project in China. The results illustrate that the proposed methodology is a simple and flexible tool for appropriately allocating emergency material to satisfy time-dynamic demands during emergency decision-making. Therefore, the decision-makers can identify an appropriate emergency material allocation scheme in a balance between time-effective and cost-effective objectives under the different emergency pollution conditions.

Dynamic joint investments in supply chains under information asymmetry

OpenAIRE

Agrell, Per Joakim; Kasperzec, Roman

2010-01-01

Supply chain management involves the selection, coordination and motivation of independently operated suppliers. However the central planner's perspective in operations management translates poorly to vertically separated chains, where suppliers may have rational myopic reasons to object to full in- formation sharing and centralized decision rights. Particular problems occur when a downstream coordinator demands relation-specific investments (equipment, cost improvements in processes, adaptat...

Neural Network Based Reactive Navigation for Mobile Robot in Dynamic Environment

Czech Academy of Sciences Publication Activity Database

Krejsa, Jiří; Věchet, S.; Ripel, T.

2013-01-01

Roč. 198, č. 2013 (2013), s. 108-113 ISSN 1012-0394 Institutional research plan: CEZ:AV0Z20760514 Institutional support: RVO:61388998 Keywords : mobile robot * reactive navigation * artificial neural networks Subject RIV: JD - Computer Applications, Robotics

Qualitative methods in nuclear reactor dynamics. Issue 23

International Nuclear Information System (INIS)

Goryachenko, V.D.

1983-01-01

Applicability of qualitative methods of the theory of nonlinear oscillations including the bifurcation theory to the problems of nuclear reactor nonlinear dynamics is investigated. Basic statements of the dynamic system qualitative theory on a phase plane and the bifurcation theory of multidimensional dynamic systems are briefly outlined. The model of reactor dynamics with two reactivity temperature coefficients neglecting delayed neutrons, the model of slow process dynamics in a reactor with two reactivity temperature coefficients, the simplified model of reactor dynamics as an object with delay and the model of a reactor with linear feedback are considered. A conclusion is drawn that the usage of the above models allows one to reveal qualitative peculiarities of reactor dynamics creating conditions for more purposeful utilization of more complicated models

Spectroscopic analysis and molecular docking of imidazole derivatives and investigation of its reactive properties by DFT and molecular dynamics simulations

Science.gov (United States)

Thomas, Renjith; Hossain, Mossaraf; Mary, Y. Sheena; Resmi, K. S.; Armaković, Stevan; Armaković, Sanja J.; Nanda, Ashis Kumar; Ranjan, Vivek Kumar; Vijayakumar, G.; Van Alsenoy, C.

2018-04-01

Solvent-free synthesis pathway for obtaining two imidazole derivatives (2-chloro-1-(4-methoxyphenyl)-4,5-dimethyl-1H-imidazole (CLMPDI) and 1-(4-bromophenyl)-2-chloro-4,5-dimethyl-1H-imidazole (BPCLDI) has been reported in this work, followed by detailed experimental and computational spectroscopic characterization and reactivity study. Spectroscopic methods encompassed IR, FT-Raman and NMR techniques, with the mutual comparison of experimentally and computationally obtained results at DFT/B3LYP level of theory. Reactivity study based on DFT calculations encompassed molecular orbitals analysis, followed by calculations of molecular electrostatic potential (MEP) and average local ionization energy (ALIE) values, Fukui functions and bond dissociation energies (BDE). Additionally, the stability of title molecules in water has been investigated via molecular dynamics (MD) simulations, while interactivity with aspulvinonedimethylallyl transferase protein has been evaluated by molecular docking procedure. CLMPDI compound showed antimicrobial activity against all four bacterial strain in both gram positive and gram negative bacteria while, BPCLDI showed only in gram positive bacteria, Staphylococcus Aureus (MTCC1144). The first order hyperpolarizability of CLMPDI and BPCLDI are 20.15 and 6.10 times that of the standard NLO material urea.

Numerical study on oil supply system of a rotary compressor

International Nuclear Information System (INIS)

Wu, Jianhua; Wang, Gang

2013-01-01

The oil supply system is a crucial reliability issue for rotary compressors. This paper provides a general method for analyzing the oil supply system of a rotary compressor by using computational fluid dynamics (CFD). The process includes establishing the physical model, dividing computational grid, setting boundary conditions, calculating leakage rates through the roller end clearances, translating the dynamic issue into the static issue and so on. Validation of the rationality of the oil supply system model has been made by the measurement of the main bearing oil flow rates. The effects of operating conditions of the compressor, the oil level height of the oil sump and the main design parameters of the oil supply system on the oil supply characteristics are analyzed by numerical simulation. It is found that the main bearing oil flow rate varies circularly along with the rotation of the shaft. The shape and inclination angle of the spiral groove also influence the main bearing oil flow rate. The oil leakage rates through the roller end clearances depend largely on the operating conditions. In addition, the oil level height of the oil sump has a huge effect on the total oil flow rate. -- Highlights: • A CFD method for analyzing the oil supply system of rotary compressor is presented. • Leakage through the roller end clearances depends on the operating condition. • Groove shape and inclination angle are the main design parameters of spiral grooves. • A parabolic interface of oil and gas can be formed in the gallery of the shaft. • Single-flow model and steady solver can be applied to the oil supply system

[Design and implementation of supply security monitoring and analysis system for Chinese patent medicines supply in national essential medicines].

Science.gov (United States)

Wang, Hui; Zhang, Xiao-Bo; Huang, Lu-Qi; Guo, Lan-Ping; Wang, Ling; Zhao, Yu-Ping; Yang, Guang

2017-11-01

The supply of Chinese patent medicine is influenced by the price of raw materials (Chinese herbal medicines) and the stock of resources. On the one hand, raw material prices show cyclical volatility or even irreversible soaring, making the price of Chinese patent medicine is not stable or even the highest cost of hanging upside down. On the other hand, due to lack of resources or disable some of the proprietary Chinese medicine was forced to stop production. Based on the micro-service architecture and Redis cluster deployment Based on the micro-service architecture and Redis cluster deployment, the supply security monitoring and analysis system for Chinese patent medicines in national essential medicines has realized the dynamic monitoring and intelligence warning of herbs and Chinese patent medicine by connecting and integrating the database of Chinese medicine resources, the dynamic monitoring system of traditional Chinese medicine resources and the basic medicine database of Chinese patent medicine. Copyright© by the Chinese Pharmaceutical Association.

Structural modification of the skin barrier by OH radicals: a reactive molecular dynamics study for plasma medicine

International Nuclear Information System (INIS)

Van der Paal, J; Verlackt, C C; Yusupov, M; Neyts, E C; Bogaerts, A

2015-01-01

While plasma treatment of skin diseases and wound healing has been proven highly effective, the underlying mechanisms, and more generally the effect of plasma radicals on skin tissue, are not yet completely understood. In this paper, we perform ReaxFF-based reactive molecular dynamics simulations to investigate the interaction of plasma generated OH radicals with a model system composed of free fatty acids, ceramides, and cholesterol molecules. This model system is an approximation of the upper layer of the skin (stratum corneum). All interaction mechanisms observed in our simulations are initiated by H-abstraction from one of the ceramides. This reaction, in turn, often starts a cascade of other reactions, which eventually lead to the formation of aldehydes, the dissociation of ceramides or the elimination of formaldehyde, and thus eventually to the degradation of the skin barrier function. (paper)

Reactive documentation system

Science.gov (United States)

Boehnlein, Thomas R.; Kramb, Victoria

2018-04-01

Proper formal documentation of computer acquired NDE experimental data generated during research is critical to the longevity and usefulness of the data. Without documentation describing how and why the data was acquired, NDE research teams lose capability such as their ability to generate new information from previously collected data or provide adequate information so that their work can be replicated by others seeking to validate their research. Despite the critical nature of this issue, NDE data is still being generated in research labs without appropriate documentation. By generating documentation in series with data, equal priority is given to both activities during the research process. One way to achieve this is to use a reactive documentation system (RDS). RDS prompts an operator to document the data as it is generated rather than relying on the operator to decide when and what to document. This paper discusses how such a system can be implemented in a dynamic environment made up of in-house and third party NDE data acquisition systems without creating additional burden on the operator. The reactive documentation approach presented here is agnostic enough that the principles can be applied to any operator controlled, computer based, data acquisition system.

The reactivity meter and core reactivity

International Nuclear Information System (INIS)

Siltanen, P.

1999-01-01

This paper discussed in depth the point kinetic equations and the characteristics of the point kinetic reactivity meter, particularly for large negative reactivities. From a given input signal representing the neutron flux seen by a detector, the meter computes a value of reactivity in dollars (ρ/β), based on inverse point kinetics. The prompt jump point of view is emphasised. (Author)

An OPF based approach for assessing the minimal reactive power support for generators in deregulated power systems

International Nuclear Information System (INIS)

Wu, H.; Yu, C.W.; Xu, N.; Lin, X.J.

2008-01-01

Reactive power support is an important ancillary service for secure and reliable operation in power markets. It has recently been recognized that the reactive power support for a generator has two components: one for supporting its own real power transmission and the other for supplying reactive demand, improving system security, and controlling system voltage; and that only the second part should receive financial compensation in competitive power markets. This makes the problem of separating these two components a new focus of current research. An OPF based reactive power optimization model along with a power flow tracing based method is proposed in this paper to tackle this problem. The methodology is tested on four test systems. Detailed analysis of the results of the 39-bus test system is reported. (author)

Supply chain simulation tools and techniques: a survey

NARCIS (Netherlands)

Kleijnen, J.P.C.

2005-01-01

The main contribution of this paper is twofold: it surveys different types of simulation for supply chain management; it discusses several methodological issues. These different types of simulation are spreadsheet simulation, system dynamics, discrete-event simulation and business games. Which

An analysis of reactivity prediction during the reactor start-up process

International Nuclear Information System (INIS)

Bajgl, Josef; Krysl, Vaclav; Svarny, Jiri

2015-01-01

The different VVER-440 core fuel loadings subcriticality evaluations are performed during the start-up process by boron dilution or control assembly withdrawn by macrocode MOBY-DICK calculations. The dynamic reactivity and quasicritical reactivity are compared and sensitivity of reactivity prediction at the low boundary of start-up interval (ρ = -0,01) has been provided on the basis of different modelling of ionization chamber (IC) response calculation. Special attention is paid to the impact of power distribution and spontaneous fission distribution form factor on IC response correction during control assembly movement. Precision and robustness of different corrections of IC signal processing in real core start-up processed IC signals was evaluated.

AIREKMOD-RR, Reactivity Transients in Nuclear Research Reactors

International Nuclear Information System (INIS)

Baggoura, B.; Mazrou, H.

2001-01-01

1 - Description of program or function: AIREMOD-RR is a point kinetics code which can simulate fast transients in nuclear research reactor cores. It can also be used for theoretical reactor dynamics studies. It is used for research reactor kinetic analysis and provides a point neutron kinetic capability. The thermal hydraulic behavior is governed by a one-dimensional heat balance equation. The calculations are restricted to a single equivalent unit cell which consists of fuel, clad and coolant. 2 - Method of solution: For transient reactor kinetic calculations a modified Runge Kutta numerical method is used. The external reactivity insertion, specified as a function of time, is converted in dollar ($) unit. The neutron density, energy release and feedback variables are given at each time step. The two types of reactivity feedback considered are: Doppler effect and moderator effect. A new expression for the reactivity dependence on the feedback variables has been introduced in the present version of the code. The feedback reactivities are fitted in power series expression. 3 - Restrictions on the complexity of the problem: The number of delayed neutron groups and the total number of equations are limited only by computer storage capabilities. - Coolant is always in liquid phase. - Void reactivity feedback is not considered

e-Commerce and supply chains: Modelling of dynamics through ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

The dynamics associated with two production planning and control policies are modelled, viz. .... Hence, there is a strong need to design a dynamic knowledge inference system .... sell a variety of components to the subassembly manufacturer.

Characteristics of a reactor with power reactivity feedback

International Nuclear Information System (INIS)

Li Fengyu; Zhang Yusheng; Zhang Guangfu; Liu Ying

2008-01-01

The point-reactor model with power reactivity feedback becomes a nonlinear system. Its dynamic characteristic shows great complexity. According to the mathematic definition of stability in differential equation qualitative theory, the model of a reactor with power reactivity feedback is judged unstable. The equilibrium point is a saddle-node point. A portion of the trajectory in the neighborhood of the equilibrium point is parabolic fan curve, and the other is hyperbolic fan curve. Based on phase locus near the equilibrium point, it is pointed out that the model is still stable within physical limits. The difference between stabilities in the mathematical sense and in the physical sense is indicated. (authors)

Modeling and Optimization for Management of Intermittent Water Supply

Science.gov (United States)

Lieb, A. M.; Wilkening, J.; Rycroft, C.

2014-12-01

In many urban areas, piped water is supplied only intermittently, as valves direct water to different parts of the water distribution system at different times. The flow is transient, and may transition between free-surface and pressurized, resulting in complex dynamical features with important consequences for water suppliers and users. These consequences include degradation of distribution system components, compromised water quality, and inequitable water availability. The goal of this work is to model the important dynamics and identify operating conditions that mitigate certain negative effects of intermittent water supply. Specifically, we will look at controlling valve parameters occurring as boundary conditions in a network model of transient, transition flow through closed pipes. Gradient-based optimization will be used to find boundary values to minimize pressure gradients and ensure equitable water availability at system endpoints.

Blind spot in free power market debate. Reactive power problems are unavoidable

International Nuclear Information System (INIS)

Maessen, T.

2002-01-01

Import restrictions, switching problems, remotely readable meters appear to be temporary problems in a liberalised power market, according to statement of the Dutch the government. However, the issues surrounding reactive power management in the Dutch transmission and distribution networks are of a far more fundamental nature. The import of cheap foreign electricity could overload the domestic power grid sufficiently to compromise the security of supply [nl

Coupled Modeling of Rhizosphere and Reactive Transport Processes

Science.gov (United States)

Roque-Malo, S.; Kumar, P.

2017-12-01

The rhizosphere, as a bio-diverse plant root-soil interface, hosts many hydrologic and biochemical processes, including nutrient cycling, hydraulic redistribution, and soil carbon dynamics among others. The biogeochemical function of root networks, including the facilitation of nutrient cycling through absorption and rhizodeposition, interaction with micro-organisms and fungi, contribution to biomass, etc., plays an important role in myriad Critical Zone processes. Despite this knowledge, the role of the rhizosphere on watershed-scale ecohydrologic functions in the Critical Zone has not been fully characterized, and specifically, the extensive capabilities of reactive transport models (RTMs) have not been applied to these hydrobiogeochemical dynamics. This study uniquely links rhizospheric processes with reactive transport modeling to couple soil biogeochemistry, biological processes, hydrologic flow, hydraulic redistribution, and vegetation dynamics. Key factors in the novel modeling approach are: (i) bi-directional effects of root-soil interaction, such as simultaneous root exudation and nutrient absorption; (ii) multi-state biomass fractions in soil (i.e. living, dormant, and dead biological and root materials); (iii) expression of three-dimensional fluxes to represent both vertical and lateral interconnected flows and processes; and (iv) the potential to include the influence of non-stationary external forcing and climatic factors. We anticipate that the resulting model will demonstrate the extensive effects of plant root dynamics on ecohydrologic functions at the watershed scale and will ultimately contribute to a better characterization of efflux from both agricultural and natural systems.

Modifying Memory: Selectively Enhancing and Updating Personal Memories for a Museum Tour by Reactivating Them

Science.gov (United States)

St. Jacques, Peggy L.; Schacter, Daniel L.

2013-01-01

Memory can be modified when reactivated, but little is known about how the properties and extent of reactivation can selectively affect subsequent memory. We developed a novel museum paradigm to directly investigate reactivation-induced plasticity for personal memories. Participants reactivated memories triggered by photos taken from a camera they wore during a museum tour and made relatedness judgments on novel photos taken from a different tour of the same museum. Subsequent recognition memory for events at the museum was better for memories that were highly reactivated (i.e., the retrieval cues during reactivation matched the encoding experience) than for memories that were reactivated at a lower level (i.e., the retrieval cues during reactivation mismatched the encoding experience), but reactivation also increased false recognition of photographs depicting stops that were not experienced during the museum tour. Reactivation thus enables memories to be selectively enhanced and distorted via updating, thereby supporting the dynamic and flexible nature of memory. PMID:23406611

Trust-Based Information Risk Management in a Supply Chain Network

OpenAIRE

Yanjun Zuo; Wen-Chen Hu

2009-01-01

Information risk management is crucial for an organization operating in an increasingly integrated and intensively communicated environment to mitigate risks and ensure core business functions. Given the open and dynamic nature of a supply chain network, information risk management is challenging and various factors must be considered. This article introduces a trust-based approach to facilitate supply chain participants to perform effective risk management. The major components of the propos...

Statistical analysis of dynamic parameters of the core

International Nuclear Information System (INIS)

Ionov, V.S.

2007-01-01

The transients of various types were investigated for the cores of zero power critical facilities in RRC KI and NPP. Dynamic parameters of neutron transients were explored by tool statistical analysis. Its have sufficient duration, few channels for currents of chambers and reactivity and also some channels for technological parameters. On these values the inverse period. reactivity, lifetime of neutrons, reactivity coefficients and some effects of a reactivity are determinate, and on the values were restored values of measured dynamic parameters as result of the analysis. The mathematical means of statistical analysis were used: approximation(A), filtration (F), rejection (R), estimation of parameters of descriptive statistic (DSP), correlation performances (kk), regression analysis(KP), the prognosis (P), statistician criteria (SC). The calculation procedures were realized by computer language MATLAB. The reasons of methodical and statistical errors are submitted: inadequacy of model operation, precision neutron-physical parameters, features of registered processes, used mathematical model in reactivity meters, technique of processing for registered data etc. Examples of results of statistical analysis. Problems of validity of the methods used for definition and certification of values of statistical parameters and dynamic characteristics are considered (Authors)

Dynamics and reactivity of confined water

International Nuclear Information System (INIS)

Musat, R.

2008-01-01

In the context of new sustainable energy sources quest, the nuclear energy remains a key solution. However, with the development of nuclear technology, problems relating to nuclear waste disposal arise; thus, the radiolysis of water in confined media is extremely important with respect to matters related to long time storage of nuclear waste. Studies in model porous media would allow the projection of a confined water radiolysis simulator. A first step in this direction was made by studying the radiolysis of water confined in Vycor and CPG glasses; this study continues the trend set and investigates the effects of confinement in metal materials upon the water radiolysis allowing the understanding of metal - water radiation induced corrosion. A further/complete understanding of the radiolytic process under confinement requires knowledge of the effect of confinement upon the dynamics of confined molecules and on the evolution of the species produced upon ionizing radiation. In this respect, we have used the OH vibrator as a probe of the hydrogen bond network properties and thus investigated the dynamics of confined water using IR time resolved spectroscopy. The evolution of the hydrated electron under confinement was studied on a nano and picosecond time scale using UV pump - visible probe technique and single shot spectroscopy. (author) [fr

Reactivation of X-irradiated cell material during limb regeneration in Urodeles Amphibians

International Nuclear Information System (INIS)

Desselle, J.C.

1979-10-01

In amputated members irradiated with X-rays the regeneration power is inhibited. This power is restored by grafts of healthy tissue in the irradiated members. The origin of the cell material of the restored regeneration blastema has been studied by an original labelling technique. The different amounts of DNA in the graft cells and those of the stump mark the graft cells during the regeneration process. It was shown that the graft causes a reactivation of the inhibited stump cells and the reactivation stages are the same as the activation stages of the member regenerating normally. It was also established that during restored regeneration the cell material implanted in the irradiated members contributes, by the 160th day of regeneration, 4.5% of the cartilaginous regenerate cells and 12% of the muscle cells. All the other regenerate cells are supplied by the cells of the stump; these are reactivated and together with the activated graft cells lead to the restitution of the amputated member [fr

The influence of reactive current on wind farm LVRT behavior

Energy Technology Data Exchange (ETDEWEB)

Li, Qing; Zhang, Mei; He, Jing; Qin, Shi-yao [China Electric Power Research Institute, Beijing (China)

2012-07-01

The Low voltage ride through (LVRT) capability of the whole wind farm is required in Chinese grid code published in 2011. In order to analyze the influence of reactive current on wind farm during grid fault, a 100 MW wind farm was simulated with the wind turbines which have been tested. Based on the validated wind turbine model, the wind farm was detailed modelled in DigSILENT/PowerFactory. The model of wind turbines, transformers, feeders, main transformers, static var compensator, and transmission lines was considered in the simulation. Under the weak and strong grid conditions, the wind farm was simulated with different wind turbine reactive current behavior during grid fault, respectively. The voltage distribution, active and reactive power transient behavior at the point of interconnection was analyzed. The results show that wind farm LVRT behavior is related to reactive current and LVRT capability of wind turbine, wind farm electrical structure and grid conditions. And it is very important for wind turbine to have a flexible dynamic reactive current control capability. (orig.)

One size does not fit all : An approach for differentiated supply chain management

OpenAIRE

Beck, Patrick; Hofmann, Erik; Stölzle, Wolfgang

2012-01-01

Supply chain management (SCM) has developed from an object of operational optimization into a strategic weapon for distinction from competitors. Dynamically changing and strongly varying customer needs demand a differentiated SCM approach. Supply chain differentiation (SCD) plans and designs supply chains based on customer needs, as increasingly demanded by SCM researchers. Therefore SCD offers a possibility to increase SCM effectiveness. While practitioners are highly interested in SCD, acad...

Diagnostic information system dynamics in the evaluation of machine learning algorithms for the supervision of energy efficiency of district heating-supplied buildings

International Nuclear Information System (INIS)

Kiluk, Sebastian

2017-01-01

Highlights: • Energy efficiency classification sustainability benefits from knowledge prediction. • Diagnostic classification can be validated with its dynamics and current data. • Diagnostic classification dynamics provides novelty extraction for knowledge update. • Data mining comparison can be performed with knowledge dynamics and uncertainty. • Diagnostic information refinement benefits form comparing classifiers dynamics. - Abstract: Modern ways of exploring the diagnostic knowledge provided by data mining and machine learning raise some concern about the ways of evaluating the quality of output knowledge, usually represented by information systems. Especially in district heating, the stationarity of efficiency models, and thus the relevance of diagnostic classification system, cannot be ensured due to the impact of social, economic or technological changes, which are hard to identify or predict. Therefore, data mining and machine learning have become an attractive strategy for automatically and continuously absorbing such dynamics. This paper presents a new method of evaluation and comparison of diagnostic information systems gathered algorithmically in district heating efficiency supervision based on exploring the evolution of information system and analyzing its dynamic features. The process of data mining and knowledge discovery was applied to the data acquired from district heating substations’ energy meters to provide the automated discovery of diagnostic knowledge base necessary for the efficiency supervision of district heating-supplied buildings. The implemented algorithm consists of several steps of processing the billing data, including preparation, segmentation, aggregation and knowledge discovery stage, where classes of abstract models representing energy efficiency constitute an information system representing diagnostic knowledge about the energy efficiency of buildings favorably operating under similar climate conditions and

State-to-state dynamics of the H{sup *}(n) + HD → D{sup *}(n{sup ′}) + H{sub 2} reactive scattering

Energy Technology Data Exchange (ETDEWEB)

Yu, Shengrui; Su, Shu; Dai, Dongxu; Yuan, Kaijun, E-mail: kjyuan@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn; Yang, Xueming, E-mail: kjyuan@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China)

2014-01-21

The state-to-state dynamics of the H{sup *}(n) + HD → D{sup *}(n{sup ′}) + H{sub 2} reactive scattering at the collision energy of 0.5 eV have been carried out for the first time by using H-atom Rydberg tagging time-of-flight technique. Experimental results show that the angular distribution of the total H{sub 2} products presents clearly forward-backward asymmetric, which considerably differs from that of the corresponding H{sup +} + HD → D{sup +} + H{sub 2} reaction predicted by previously theoretical calculations. Such disagreement between these two processes suggests that the Fermi independent-collider model is also not valid in describing the dynamics of isotopic variants of the H{sup *} + H{sub 2} reaction. The rotational state distribution of the H{sub 2} products demonstrates a saw-toothed distribution with odd-j{sup ′} > even-j{sup ′}. This interesting observation is strongly influenced by nuclear spin statistics.

DMPD: NF-kappaB activation by reactive oxygen species: fifteen years later. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 16723122 NF-kappaB activation by reactive oxygen species: fifteen years later. Gloi...svg) (.html) (.csml) Show NF-kappaB activation by reactive oxygen species: fifteen years later. PubmedID 167...23122 Title NF-kappaB activation by reactive oxygen species: fifteen years later.

Estimating demand and supply of edible oil in Pakistan

OpenAIRE

Haq, Rashida

1991-01-01

This paper examines the demand for edible oil in Pakistan and a dynamic supply response model to show price responsiveness by sunflower oilseed farmers. The demand for edible oil is estimated by using Ordinary Least Square (OLS) technique. It has been found that an increase in the consumption of edible oil is highly affected by urbanization, increase in per capita income, relative high price of its substitutes and the rapid growth of the population. In order to estimate supply response model ...

Supply Chain Simulation: A Survey

OpenAIRE

Kleijnen, J.P.C.

2003-01-01

This paper provides a survey of simulation in supply chain management.It reviews four types of simulation, namely spreadsheet simulation, system dynamics, discreteevent simulation, and business games.Which simulation type should be applied, depends on the type of managerial question to be answered by the model.Moreover, this paper summarizes novel sensitivity and robustness analyses.This sensitivity analysis yields a shortlist of the truly important factors in large simulation models with (sa...

Supply and demand perspectives

International Nuclear Information System (INIS)

Trienekens, Pieter

1999-01-01

The outlook for the European gas market is one of steady growth. This growth will manifest itself in all regions and in all sectors of the market, but most strongly in the power generating sector. To meet future demand, it is necessary to bring gas to Western Europe from remote sources in Russia, North Africa and Norway. These new gas supplies require heavy investments in production and transportation, which can only be undertaken on the basis of long-term take-or-pay contracts. Famous examples of such contracts are the development of the Troll field, the Yamal-Europe pipeline connection, and the bringing on stream of Nigerian LNG for Europe. Tensions are likely to arise between the nature of these long-term gas contracts and the dynamic nature of demand in the gas market, and more specifically in the main growth market, the power sector. The presentation further elaborates on the tensions underlying supply and demand in the years to come

A range of newly developed mobile generators to dynamically produce SI-traceable reference gas mixtures for reactive compounds at atmospheric concentrations

Science.gov (United States)

Leuenberger, Daiana; Pascale, Céline; Guillevic, Myriam; Ackermann, Andreas; Niederhauser, Bernhard

2017-04-01

Three new mobile facilities have been developed at METAS to dynamically generate SI-traceable reference gas mixtures for a variety of reactive compounds at atmospheric amount of substance fractions and at very low levels of uncertainty (Ux balance. The carrier gas is previously purified from the compounds of interest using commercially available purification cartridges. The permeation chambers of ReGaS2 and ReGaS3 have multiple individual cells allowing for the generation of mixtures containing up to 5 different components if required. ReGaS1 allows for the generation of one-component mixtures only. These primary mixtures are then diluted to the required amount of substance fractions using thermal mass flow controllers for full flexibility and adaptability of the generation process over the entire range of possible concentrations. In order to considerably reduce adsorption/desorption processes and thus stabilisation time, all electro-polished stainless steel parts of ReGaS1 and ReGaS2 in contact with the reference gas mixtures are passivated with SilcoNert2000® surface coating. These three state-of-the-art mobile reference gas generators are applicable under both, laboratory and field conditions. Moreover the dynamic generation method can be adapted and applied to a large variety of molecules (e.g. BTEX, CFCs, HCFCs, HFCs and other refrigerants) and is particularly suitable for reactive gas species and/or at concentration ranges which are unstable when stored in pressurised cylinders. Acknowledgement: This work was supported by the European Metrology Research Programme (EMRP). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union

MODEL DINAMIS SUPPLY CHAIN BERAS BERKELANJUTAN DALAM UPAYA KETAHANAN PANGAN NASIONAL

Directory of Open Access Journals (Sweden)

Akhmad Mahbubi

2014-09-01

Full Text Available ABSTRACTThis study was aimed to 1 identify the basic system of rice supply chain, 2 design a conceptual system and formulate a model of rice supply chain to achieve rice food security and 3 identify the sustainability behavior of the rice supply chain systems for the next 30 years from the aspects of economical revenue, social welfare and environment. Dynamic model was used to analyze the data. Referring to a variety of technical indicators achievement in the blueprint of national food security, several policy scenarios were used in the analysis of the behavior of rice supply chain systems until 2042 in economical revenue, social welfare and the environment aspects. The results of this study showed that the self-sufficiency of rice will continue until 2042 (the end of the study’s simulation. It also showed that in the long run, national rice food security will be disrupted if the government does not stop the conversion of agricultural land. Therefore, the government needs to issue a policy related to the conversion of agricultural land, especially paddy fields for infrastructure development.Keywords: rice, sustainable, food security, dynamic models, supply chainABSTRAKTujuan Penelitian adalah 1 mengidentifikasi sistem dasar supply chain beras, 2 menyusun konseptual sistem dan formulasi model supply chain beras untuk pencapaian ketahanan pangan nasional, serta 3 mengetahui perilaku sistem supply chain beras untuk 30 tahun kedepan tetap berkelanjutan dilihat dari aspek pendapatan ekonomi, sosial dan lingkungan. Analisis data menggunakan model dinamis. Beberapa skenario dalam analisis perilaku supply chain beras sampai tahun 2042 dilihat dari aspek pendapatan ekonomi, sosial dan lingkungan mengacu pada indikator pencapaian dalam blue print ketahanan pangan nasional. Hasil penelitian ini, swasembada pangan beras akan berkelanjutan sampai 2042 (akhir dari simulasi penelitian ini. Dalam jangka panjang, ketahanan pangan beras nasional akan terganggu

Embedded Cluster Models for Reactivity of the Hydrated Electron

Czech Academy of Sciences Publication Activity Database

Uhlig, Frank; Jungwirth, Pavel

2013-01-01

Roč. 227, č. 11 (2013), s. 1583-1593 ISSN 0942-9352 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : hydrated electron * clusters * reactivity * ab initio molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.178, year: 2013

Reactive transport in a partially molten system with binary solid solution

Science.gov (United States)

Jordan, J.; Hesse, M. A.

2017-12-01

Melt extraction from the Earth's mantle through high-porosity channels is required to explain the composition of the oceanic crust. Feedbacks from reactive melt transport are thought to localize melt into a network of high-porosity channels. Recent studies invoke lithological heterogeneities in the Earth's mantle to seed the localization of partial melts. Therefore, it is necessary to understand the reaction fronts that form as melt flows across the lithological interface of a heterogeneity and the background mantle. Simplified melting models of such systems aide in the interpretation and formulation of larger scale mantle models. Motivated by the aforementioned facts, we present a chromatographic analysis of reactive melt transport across lithological boundaries, using theory for hyperbolic conservation laws. This is an extension of well-known linear trace element chromatography to the coupling of major elements and energy transport. Our analysis allows the prediction of the feedbacks that arise in reactive melt transport due to melting, freezing, dissolution and precipitation for frontal reactions. This study considers the simplified case of a rigid, partially molten porous medium with binary solid solution. As melt traverses a lithological contact-modeled as a Riemann problem-a rich set of features arise, including a reacted zone between an advancing reaction front and partial chemical preservation of the initial contact. Reactive instabilities observed in this study originate at the lithological interface rather than along a chemical gradient as in most studies of mantle dynamics. We present a regime diagram that predicts where reaction fronts become unstable, thereby allowing melt localization into high-porosity channels through reactive instabilities. After constructing the regime diagram, we test the one-dimensional hyperbolic theory against two-dimensional numerical experiments. The one-dimensional hyperbolic theory is sufficient for predicting the

Extended reactivity trace curves for nuclear power control with no power shooting

Energy Technology Data Exchange (ETDEWEB)

Ratemi, W M; Elbuni, M S [Faculty of engineering, Al Fateh universty Tripoli (Libyan Arab Jamahiriya)

1995-10-01

This paper introduces a new concept of reactivity trace curve (RTC) for nuclear power control with no power shooting. The concept is based on recent work of bernard et al. on the dynamic period of nuclear reactors. RTC-method is simulated for both a static effective decay constant corresponding to a one-group delayed neutrons model, and a dynamic effective decay constant corresponding to a six-group delayed neutrons model. A fitting to the RTC of a six-group reactor model resulted in a closed from formula for the RTC that couples the effect of both static and dynamic decay constants. Hence, introducing two `fingerprints` for the reactor in concern to identify a closed from RTC formula capable of controlling the reactor power. Integration of the RTC with control rod integral curves results in the {rho}-z-t diagram. This diagram relates the amount of recommended reactivity (RTC), the position of control rod, and the time required for power control. 8 figs.

Extended reactivity trace curves for nuclear power control with no power shooting

International Nuclear Information System (INIS)

Ratemi, W. M.; Elbuni, M. S.

1995-01-01

This paper introduces a new concept of reactivity trace curve (RTC) for nuclear power control with no power shooting. The concept is based on recent work of bernard et al. on the dynamic period of nuclear reactors. RTC-method is simulated for both a static effective decay constant corresponding to a one-group delayed neutrons model, and a dynamic effective decay constant corresponding to a six-group delayed neutrons model. A fitting to the RTC of a six-group reactor model resulted in a closed from formula for the RTC that couples the effect of both static and dynamic decay constants. Hence, introducing two 'fingerprints' for the reactor in concern to identify a closed from RTC formula capable of controlling the reactor power. Integration of the RTC with control rod integral curves results in the ρ-z-t diagram. This diagram relates the amount of recommended reactivity (RTC), the position of control rod, and the time required for power control. 8 figs

DIII-D ICRF high voltage power supply regulator upgrade

International Nuclear Information System (INIS)

Cary, W.P.; Burley, B.L.; Grosnickle, W.H.

1997-11-01

For reliable operation and component protection, of the 2 MW 30--120 MHz ICRF Amplifier System on DIII-D, it is desirable for the amplifier to respond to high VSWR conditions as rapidly as possible. This requires a rapid change in power which also means a rapid change in the high voltage power supply current demands. An analysis of the power supply's regulator dynamics was needed to verify its expected operation during such conditions. Based on this information it was found that a new regulator with a larger dynamic range and some anticipation capability would be required. This paper will discuss the system requirements, the as-delivered regulator performance, and the improved performance after installation of the new regulator system. It will also be shown how this improvement has made the amplifier perform at higher power levels more reliably

Neural mechanisms of reactivation-induced updating that enhance and distort memory.

Science.gov (United States)

St Jacques, Peggy L; Olm, Christopher; Schacter, Daniel L

2013-12-03

We remember a considerable number of personal experiences because we are frequently reminded of them, a process known as memory reactivation. Although memory reactivation helps to stabilize and update memories, reactivation may also introduce distortions if novel information becomes incorporated with memory. Here we used functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms mediating reactivation-induced updating in memory for events experienced during a museum tour. During scanning, participants were shown target photographs to reactivate memories from the museum tour followed by a novel lure photograph from an alternate tour. Later, participants were presented with target and lure photographs and asked to determine whether the photographs showed a stop they visited during the tour. We used a subsequent memory analysis to examine neural recruitment during reactivation that was associated with later true and false memories. We predicted that the quality of reactivation, as determined by online ratings of subjective recollection, would increase subsequent true memories but also facilitate incorporation of the lure photograph, thereby increasing subsequent false memories. The fMRI results revealed that the quality of reactivation modulated subsequent true and false memories via recruitment of left posterior parahippocampal, bilateral retrosplenial, and bilateral posterior inferior parietal cortices. However, the timing of neural recruitment and the way in which memories were reactivated contributed to differences in whether memory reactivation led to distortions or not. These data reveal the neural mechanisms recruited during memory reactivation that modify how memories will be subsequently retrieved, supporting the flexible and dynamic aspects of memory.

Simulation of dynamics behaviors for shipping equipment support with system dynamics analysis approach

Directory of Open Access Journals (Sweden)

Yang Song

2015-05-01

Full Text Available Purpose: The exactly and precisely supply of carrying spare parts has a crucial impact on support and could improve the performance of equipment. Spare parts support is the crux work which will be limited by spare parts allocation and support cost input. Reasonable support strategy can help in making good use of available resources and support the equipment in normal operational status. The purpose of this paper is to propose a dynamics model of spare parts support process based on considering the interaction of multiple factors, and explores the regulation of dynamics behavior in the system. In order to achieve the optimization strategy to improve the effect of support so that will enhance the relevant support parameters of equipment. Design/methodology/approach: Meditate the feedback relationship among some important factors of support that involve support cost, support time and maintenance ability. System dynamics theory is adopted to propose a dynamics model of spare parts support process, on the analysis of multiple factors and casual relationship to find some major ones which have crucial impact on spare parts support. Spare parts support cost and availability was regarded as the control objective, moreover, adjust the control paramours and improve the effect of cannibalization and lateral supply scheduling strategy for spares support. Findings: The factors of spare parts supply, demand and maintenance have relationship of control feedback, and adjust the value of some crucial factors can reduce the support cost and improve the availability value. The main finding is that adopting cannibalization strategy under condition of available materials can relieve the mission and operational availability decline caused by shortage of spare parts. Combining the lateral supply and cannibalization strategy can reduce the inventory of warship carrying spare parts. Practical implications: By controlling the value of key factors regarding aspect of spare

Quantum approaches for the insertion dynamics of the H++D2 and D++H2 reactive collisions

International Nuclear Information System (INIS)

Gonzalez-Lezana, Tomas; Aguado, Alfredo; Paniagua, Miguel; Roncero, O.

2005-01-01

The H + +D 2 and D + +H 2 reactive collisions are studied using a recently proposed adiabatic potential energy surface of spectroscopic accuracy. The dynamics is studied using an exact wave packet method on the adiabatic surface at energies below the curve crossing occurring at ≅1.5 eV above the threshold. It is found that the reaction is very well described by a statistical quantum method for a zero total angular momentum (J) as compared with the exact ones, while for higher J some discrepancies are found. For J>0 different centrifugal sudden approximations are proposed and compared with the exact and statistical quantum treatments. The usual centrifugal sudden approach fails by considering too high reaction barriers and too low reaction probabilities. A new statistically modified centrifugal sudden approach is considered which corrects these two failures to a rather good extent. It is also found that an adiabatic approximation for the helicities provides results in very good agreement with the statistical method, placing the reaction barrier properly. However, both statistical and adiabatic centrifugal treatments overestimate the reaction probabilities. The reaction cross sections thus obtained with the new approaches are in rather good agreement with the exact results. In spite of these deficiencies, the quantum statistical method is well adapted for describing the insertion dynamics, and it is then used to evaluate the differential cross sections

Designing Leadership models in a Three Level Unlimited Supply Chain: Non-Cooperative Game Theory Approach

Directory of Open Access Journals (Sweden)

Ahmad Jaafarnehad

2015-09-01

Full Text Available The role and importance of supply chain management, has faced with many challenges and problems. Although a comprehensive model of supply chain issues, has not been explained, we have to indicate that issues such as reviewing the theoretical foundations of information systems, marketing, financial management, logistical and organizational relations have been considered by many researchers. The objective of supply chain management is to improve various activities and components to increase overall supply chain system benefits. In order to achieve the overall objectives, many contradictions may occur between the components and different levels of supply chain and the contradictions that these disorders over time, result in decreased strength and competitiveness of the supply chain. Such conflicts, like marketing costs (advertising, pricing and inventory can occur during the supply chain life cycle. A Game Theory approach with respect to property is the appropriate tool for collaboration in the supply chain. This tool is used for collaborative making in any kind of supply chain such as cooperative supply chain and non-cooperative supply chain. In the present study and assuming a lack of cooperation between different levels of a supply chain, a dynamic game with complete information has been generated. In addition identifying appropriate leaders of various levels of the supply chain is considered. Non-Cooperative dynamic game mode (Stackelberg Game, for each of the three levels of supply chain including retailers, suppliers and manufacturers are modeled. Depending on the bargaining power and its position in the market, any level of supply chain can make a leader of the following rule. In the present study, the equilibrium model to play Stackelberg game may be led by a leader or leading players and ultimately identifying and modeling the appropriate unlimited three level supply chain are determined.

Reactivity changes in hybrid thermal-fast reactor systems during fast core flooding

International Nuclear Information System (INIS)

Pesic, M.

1994-09-01

A new space-dependent kinetic model in adiabatic approximation with local feedback reactivity parameters for reactivity determination in the coupled systems is proposed in this thesis. It is applied in the accident calculation of the 'HERBE' fast-thermal reactor system and compared to usual point kinetics model with core-averaged parameters. Advantages of the new model - more realistic picture of the reactor kinetics and dynamics during local large reactivity perturbation, under the same heat transfer conditions, are underlined. Calculated reactivity parameters of the new model are verified in the experiments performed at the 'HERBE' coupled core. The model has shown that the 'HERBE' safety system can shutdown reactor safely and fast even in the case of highly set power trip and even under conditions of big partial failure of the reactor safety system (author)

An Improved Droop Control Strategy for Reactive Power Sharing in Islanded Microgrid

DEFF Research Database (Denmark)

Han, Hua; Liu, Yao; Sun, Yao

2015-01-01

For microgrid in islanded operation, due to the effects of mismatched line impedance, the reactive power could not be shared accurately with the conventional droop method. To improve the reactive power sharing accuracy, this paper proposes an improved droop control method. The proposed method...... in output voltage amplitude. Therefore, the voltage recovery operation is proposed to compensate the decrease. The needed communication in this method is very simple, and the plug-and-play is reserved. Simulations and experimental results show that the improved droop controller can share load active...... and reactive power, improve the power quality of the microgrid, and also have a good dynamic performance....

Process Improvement of Reactive Dye Synthesis Using Six Sigma Concept

Science.gov (United States)

Suwanich, Thanapat; Chutima, Parames

2017-06-01

This research focuses on the problem occurred in the reactive dye synthesis process of a global manufacturer in Thailand which producing various chemicals for reactive dye products to supply global industries such as chemicals, textiles and garments. The product named “Reactive Blue Base” is selected in this study because it has highest demand and the current chemical yield shows a high variation, i.e. yield variation of 90.4% - 99.1% (S.D. = 2.405 and Cpk = -0.08) and average yield is 94.5% (lower than the 95% standard set by the company). The Six Sigma concept is applied aiming at increasing yield and reducing variation of this process. This approach is suitable since it provides a systematic guideline with five improvement phases (DMAIC) to effectively tackle the problem and find the appropriate parameter settings of the process. Under the new parameter settings, the process yield variation is reduced to range between 96.5% - 98.5% (S.D. = 0.525 and Cpk = 1.83) and the average yield is increased to 97.5% (higher than the 95% standard set by the company).

The chaos and control of a food chain model supplying additional food to top-predator

International Nuclear Information System (INIS)

Sahoo, Banshidhar; Poria, Swarup

2014-01-01

Highlights: • We propose a chaotic food chain model supplying additional food to top-predator. • Local and global stability conditions are derived in presence of additional food. • Chaos is controlled only by increasing quantity of additional food. • System enters into periodic region and depicts Hopf bifurcations supplying additional food. • This an application of non-chemical methods for controlling chaos. -- Abstract: The control and management of chaotic population is one of the main objectives for constructing mathematical model in ecology today. In this paper, we apply a technique of controlling chaotic predator–prey population dynamics by supplying additional food to top-predator. We formulate a three species predator–prey model supplying additional food to top-predator. Existence conditions and local stability criteria of equilibrium points are determined analytically. Persistence conditions for the system are derived. Global stability conditions of interior equilibrium point is calculated. Theoretical results are verified through numerical simulations. Phase diagram is presented for various quality and quantity of additional food. One parameter bifurcation analysis is done with respect to quality and quantity of additional food separately keeping one of them fixed. Using MATCONT package, we derive the bifurcation scenarios when both the parameters quality and quantity of additional food vary together. We predict the existence of Hopf point (H), limit point (LP) and branch point (BP) in the model for suitable supply of additional food. We have computed the regions of different dynamical behaviour in the quantity–quality parametric plane. From our study we conclude that chaotic population dynamics of predator prey system can be controlled to obtain regular population dynamics only by supplying additional food to top predator. This study is aimed to introduce a new non-chemical chaos control mechanism in a predator–prey system with the

State-to-state inelastic and reactive molecular beam scattering from surfaces

International Nuclear Information System (INIS)

Lykke, K.R.; Kay, B.D.

1990-01-01

Resonantly enhanced multiphoton ionization (REMPI) laser spectroscopic and molecular beam-surface scattering techniques are coupled to study inelastic and reactive gas-surface scattering with state-to-state specificity. Rotational, vibrational, translational and angular distributions have been measured for the inelastic scattering of HCI and N 2 from Au(111). In both cases the scattering is direct-inelastic in nature and exhibits interesting dynamical features such as rotational rainbow scattering. In an effort to elucidate the dynamics of chemical reactions occurring on surfaces we have extended our quantum-resolved scattering studies to include the reactive scattering of a beam of gas phase H-atoms from a chlorinated metal surface M-CI. The nascent rotational and vibrational distributions of the HCI product are determined using REMPI. The thermochemistry for this reaction on Au indicates that the product formation proceeding through chemisorbed H-atoms is slightly endothermic while direct reaction of a has phase H-atom with M-CI is highly exothermic (ca. 50 kcal/mole). Details of the experimental techniques, results and implications regarding the scattering dynamics are discussed. 55 ref., 8 fig

Cue-independent memory impairment by reactivation-coupled interference in human declarative memory.

Science.gov (United States)

Zhu, Zijian; Wang, Yingying; Cao, Zhijun; Chen, Biqing; Cai, Huaqian; Wu, Yanhong; Rao, Yi

2016-10-01

Memory is a dynamic process. While memory becomes increasingly resistant to interference after consolidation, a brief reactivation renders it unstable again. Previous studies have shown that interference, when applied upon reactivation, impairs the consolidated memory, presumably by disrupting the reconsolidation of the memory. However, attempts have failed in disrupting human declarative memory, raising a question about whether declarative memory becomes unstable upon reactivation. Here, we used a double-cue/one-target paradigm, which associated the same target with two different cues in initial memory formation. Only one cue/target association was later reactivated and treated with behavioral interference. Our results showed, for the first time, that reactivation-coupled interference caused cue-independent memory impairment that generalized to other cues associated with the memory. Critically, such memory impairment appeared immediately after interference, before the reconsolidation process was completed, suggesting that common manipulations of reactivation-coupled interference procedures might disrupt other processes in addition to the reconsolidation process in human declarative memory. Copyright © 2016. Published by Elsevier B.V.

Modeling the resilience of urban water supply using the capital portfolio approach

Science.gov (United States)

Krueger, E. H.; Klammler, H.; Borchardt, D.; Frank, K.; Jawitz, J. W.; Rao, P. S.

2017-12-01

The dynamics of global change challenge the resilience of cities in a multitude of ways, including pressures resulting from population and consumption changes, production patterns, climate and landuse change, as well as environmental hazards. Responses to these challenges aim to improve urban resilience, but lack an adequate understanding of 1) the elements and processes that lead to the resilience of coupled natural-human-engineered systems, 2) the complex dynamics emerging from the interaction of these elements, including the availability of natural resources, infrastructure, and social capital, which may lead to 3) unintended consequences resulting from management responses. We propose a new model that simulates the coupled dynamics of five types of capitals (water resources, infrastructure, finances, political capital /management, and social adaptive capacity) that are necessary for the provision of water supply to urban residents. We parameterize the model based on data for a case study city, which is limited by constraints in water availability, financial resources, and faced with degrading infrastructure, as well as population increase, which challenge the urban management institutions. Our model analyzes the stability of the coupled system, and produces time series of the capital dynamics to quantify its resilience as a result of the portfolio of capitals available to usher adaptive capacity and to secure water supply subjected to multiple recurring shocks. We apply our model to one real urban water supply system located in an arid environment, as well as a wide range of hypothetical case studies, which demonstrates its applicability to various types of cities, and its ability to quantify and compare water supply resilience. The analysis of a range of urban water systems provides valuable insights into guiding more sustainable responses for maintaining the resilience of urban water supply around the globe, by showing how unsustainable responses risk the

Proliferative reactive gliosis is compatible with glial metabolic support and neuronal function

Directory of Open Access Journals (Sweden)

Fero Matthew

2011-10-01

Full Text Available Abstract Background The response of mammalian glial cells to chronic degeneration and trauma is hypothesized to be incompatible with support of neuronal function in the central nervous system (CNS and retina. To test this hypothesis, we developed an inducible model of proliferative reactive gliosis in the absence of degenerative stimuli by genetically inactivating the cyclin-dependent kinase inhibitor p27Kip1 (p27 or Cdkn1b in the adult mouse and determined the outcome on retinal structure and function. Results p27-deficient Müller glia reentered the cell cycle, underwent aberrant migration, and enhanced their expression of intermediate filament proteins, all of which are characteristics of Müller glia in a reactive state. Surprisingly, neuroglial interactions, retinal electrophysiology, and visual acuity were normal. Conclusion The benign outcome of proliferative reactive Müller gliosis suggests that reactive glia display context-dependent, graded and dynamic phenotypes and that reactivity in itself is not necessarily detrimental to neuronal function.

Electrical Power Supply to Offshore Oil Installations by High Voltage Direct Current Transmission

Energy Technology Data Exchange (ETDEWEB)

Myhre, Joergen Chr.

2001-07-01

of the main features when the details of the transients are of less importance. The study indicates that power supply by HVDC transmission from land to offshore oil installations could be technically feasible, even without the large synchronous compensators normally required. It has been shown that in a network only supplied by an inverter, variations of active and reactive loads have significant influence on both voltage and frequency. Particularly it should be noted that the frequency shows a positive sensitivity to increases in load. This could make the system intrinsically unstable in the case of a frequency dependent load such as motors. It was not a part of the study to optimize controllers, but even with simple controllers it was possible to keep the frequency within limits given by norms and regulations, but the voltages were dynamically outside the limits, though not very far. These voltage overswings take place in the first few instances after a disturbance, so it takes unrealistically fast controllers to handle them. They are partly due to the model, where the land based rectifier and the DC reactors are simulated by a constant current source, but partly they have to be handled by overdimensioning of the system. The simulations indicate that it should be technically possible to supply an oil platform with electrical power from land by means of HVDC transmission with small synchronous compensators. Whether this is financially feasible has not been investigated. Neither has it been considered whether the necessary equipment can actually be installed on an oil platform. Recently both ABB and Siemens have presented solutions for HVDC transmission in the lower and medium power range based on voltage source converters based on IGBTs. Fully controllable voltage source HVDC converters have properties that may be better suited than conventional line commutated current source thyristor inverters, to supply weak or passive networks, such as offshore oil installations

Collaborative Manufacturing Management in Networked Supply Chains

Science.gov (United States)

Pouly, Michel; Naciri, Souleiman; Berthold, Sébastien

ERP systems provide information management and analysis to industrial companies and support their planning activities. They are currently mostly based on theoretical values (averages) of parameters and not on the actual, real shop floor data, leading to disturbance of the planning algorithms. On the other hand, sharing data between manufacturers, suppliers and customers becomes very important to ensure reactivity towards markets variability. This paper proposes software solutions to address these requirements and methods to automatically capture the necessary corresponding shop floor information. In order to share data produced by different legacy systems along the collaborative networked supply chain, we propose to use the Generic Product Model developed by Hitachi to extract, translate and store heterogeneous ERP data.

Increasing Capacity Exploitation in Food Supply Chains Using Grid Concepts

Science.gov (United States)

Volk, Eugen; Müller, Marcus; Jacob, Ansger; Racz, Peter; Waldburger, Martin

Food supply chains today are characterized by fixed trade relations with long term contracts established between heterogeneous supply chain companies. Production and logistics capacities of these companies are often utilized in an economically inefficient manner only. In addition, increased consumer awareness in food safety issues renders supply chain management even more challenging, since integrated tracking and tracing along the whole food supply chain is needed. Facing these issues of supply chain management complexity and completely documented product quality, this paper proposes a full lifecycle solution for dynamic capacity markets based on concepts used in the field of Grid [1], like management of Virtual Organization (VO) combined with Service Level Agreement (SLA). The solution enables the cost-efficient utilization of real world capacities (e.g., production capacities or logistics facilities) by using a simple, browser-based portal. Users are able to enter into product-specific negotiations with buyers and suppliers of a food supply chain, and to obtain real-time access to product information including SLA evaluation reports. Thus, business opportunities in wider market access, process innovation, and trustworthy food products are offered for participating supply chain companies.

Land transportation model for supply chain manufacturing industries

Science.gov (United States)

Kurniawan, Fajar

2017-12-01

Supply chain is a system that integrates production, inventory, distribution and information processes for increasing productivity and minimize costs. Transportation is an important part of the supply chain system, especially for supporting the material distribution process, work in process products and final products. In fact, Jakarta as the distribution center of manufacturing industries for the industrial area. Transportation system has a large influences on the implementation of supply chain process efficiency. The main problem faced in Jakarta is traffic jam that will affect on the time of distribution. Based on the system dynamic model, there are several scenarios that can provide solutions to minimize timing of distribution that will effect on the cost such as the construction of ports approaching industrial areas other than Tanjung Priok, widening road facilities, development of railways system, and the development of distribution center.

Metabolic dynamics in skeletal muscle during acute reduction in blood flow and oxygen supply to mitochondria: in-silico studies using a multi-scale, top-down integrated model.

Science.gov (United States)

Dash, Ranjan K; Li, Yanjun; Kim, Jaeyeon; Beard, Daniel A; Saidel, Gerald M; Cabrera, Marco E

2008-09-09

Control mechanisms of cellular metabolism and energetics in skeletal muscle that may become evident in response to physiological stresses such as reduction in blood flow and oxygen supply to mitochondria can be quantitatively understood using a multi-scale computational model. The analysis of dynamic responses from such a model can provide insights into mechanisms of metabolic regulation that may not be evident from experimental studies. For the purpose, a physiologically-based, multi-scale computational model of skeletal muscle cellular metabolism and energetics was developed to describe dynamic responses of key chemical species and reaction fluxes to muscle ischemia. The model, which incorporates key transport and metabolic processes and subcellular compartmentalization, is based on dynamic mass balances of 30 chemical species in both capillary blood and tissue cells (cytosol and mitochondria) domains. The reaction fluxes in cytosol and mitochondria are expressed in terms of a general phenomenological Michaelis-Menten equation involving the compartmentalized energy controller ratios ATP/ADP and NADH/NAD(+). The unknown transport and reaction parameters in the model are estimated simultaneously by minimizing the differences between available in vivo experimental data on muscle ischemia and corresponding model outputs in coupled with the resting linear flux balance constraints using a robust, nonlinear, constrained-based, reduced gradient optimization algorithm. With the optimal parameter values, the model is able to simulate dynamic responses to reduced blood flow and oxygen supply to mitochondria associated with muscle ischemia of several key metabolite concentrations and metabolic fluxes in the subcellular cytosolic and mitochondrial compartments, some that can be measured and others that can not be measured with the current experimental techniques. The model can be applied to test complex hypotheses involving dynamic regulation of cellular metabolism and

The Dynamics Of Food Security In Sub-Saharan Africa

Directory of Open Access Journals (Sweden)

Degye Goshu

2017-09-01

Full Text Available This paper examines the dynamics of food supply per capita and undernourishment in Sub-Saharan Africa SSA for a panel of 42 countries. The dataset was constructed from the FAO and the World Bank global databases for four rounds in five-year intervals. Ordinal measures of national food supply status were generated from daily calorie supply per capita of SSA countries. Regional and inter-temporal dynamics of food supply status very low low medium transition rates and the associated forces underpinning this dynamic process were analyzed and stylized by parametric and non-parametric measures. Economic and socio-demographic factors and regional heterogeneities determining the dynamics of food supply situation in SSA were identified by random-effects ordered probit model. The empirical findings indicate that the food supply level of SSA countries was enhanced by agricultural production and industrial value added as a proxy for structural transformation. However it was adversely affected by military expenditure inflation level of consumer prices proportion of rural population age dependency ratio and regional heterogeneities. The likelihood of SSA countries to face incidence of very low low and medium calorie per capita supply was 23 percent 61 percent and 16 percent respectively. To improve the level of food supply per capita and thereby to reduce food poverty situation SSA countries and other stakeholders need to focus on policies designed to enhance economic growth through agricultural production creation of employment opportunities with structural transformation enhancing health care services improving their demographic structure through family planning and controlling national and regional shocks and instabilities.

Digital Piracy: An Assessment of Consumer Piracy Risk and Optimal Supply Chain Coordination Strategies

Science.gov (United States)

Jeong, Bong-Keun

2010-01-01

Digital piracy and the emergence of new distribution channels have changed the dynamics of supply chain coordination and created many interesting problems. There has been increased attention to understanding the phenomenon of consumer piracy behavior and its impact on supply chain profitability. The purpose of this dissertation is to better…

Flow rate of transport network controls uniform metabolite supply to tissue.

Science.gov (United States)

Meigel, Felix J; Alim, Karen

2018-05-01

Life and functioning of higher organisms depends on the continuous supply of metabolites to tissues and organs. What are the requirements on the transport network pervading a tissue to provide a uniform supply of nutrients, minerals or hormones? To theoretically answer this question, we present an analytical scaling argument and numerical simulations on how flow dynamics and network architecture control active spread and uniform supply of metabolites by studying the example of xylem vessels in plants. We identify the fluid inflow rate as the key factor for uniform supply. While at low inflow rates metabolites are already exhausted close to flow inlets, too high inflow flushes metabolites through the network and deprives tissue close to inlets of supply. In between these two regimes, there exists an optimal inflow rate that yields a uniform supply of metabolites. We determine this optimal inflow analytically in quantitative agreement with numerical results. Optimizing network architecture by reducing the supply variance over all network tubes, we identify patterns of tube dilation or contraction that compensate sub-optimal supply for the case of too low or too high inflow rate. © 2018 The Authors.

Application of GO methodology in reliability analysis of offsite power supply of Daya Bay NPP

International Nuclear Information System (INIS)

Shen Zupei; Li Xiaodong; Huang Xiangrui

2003-01-01

The author applies the GO methodology to reliability analysis of the offsite power supply system of Daya Bay NPP. The direct quantitative calculation formulas of the stable reliability target of the system with shared signals and the dynamic calculation formulas of the state probability for the unit with two states are derived. The method to solve the fault event sets of the system is also presented and all the fault event sets of the outer power supply system and their failure probability are obtained. The resumption reliability of the offsite power supply system after the stability failure of the power net is also calculated. The result shows that the GO methodology is very simple and useful in the stable and dynamic reliability analysis of the repairable system

Supply Chain Development: Insights from Strategic Niche Management

Science.gov (United States)

Caniels, Marjolein C. J.; Romijn, Henny A.

2008-01-01

Purpose: The purpose of this paper is to contribute to the study of supply chain design from the perspective of complex dynamic systems. Unlike extant studies that use formal simulation modelling and associated methodologies rooted in the physical sciences, it adopts a framework rooted in the social sciences, strategic niche management, which…

Exploring the conformational and reactive dynamics of biomolecules in solution using an extended version of the glycine reactive force field

DEFF Research Database (Denmark)

Monti, Susanna; Corozzi, Alessandro; Fristrup, Peter

2013-01-01

In order to describe possible reaction mechanisms involving amino acids, and the evolution of the protonation state of amino acid side chains in solution, a reactive force field (ReaxFF-based description) for peptide and protein simulations has been developed as an expansion of the previously rep...

Optimal Allocation of Water Resources Based on Water Supply Security

Directory of Open Access Journals (Sweden)

Jianhua Wang

2016-06-01

Full Text Available Under the combined impacts of climate change and human activities, a series of water issues, such as water shortages, have arisen all over the world. According to current studies in Science and Nature, water security has become a frontier critical topic. Water supply security (WSS, which is the state of water resources and their capacity and their capacity to meet the demand of water users by water supply systems, is an important part of water security. Currently, WSS is affected by the amount of water resources, water supply projects, water quality and water management. Water shortages have also led to water supply insecurity. WSS is now evaluated based on the balance of the supply and demand under a single water resources condition without considering the dynamics of the varying conditions of water resources each year. This paper developed an optimal allocation model for water resources that can realize the optimal allocation of regional water resources and comprehensively evaluate WSS. The objective of this model is to minimize the duration of water shortages in the long term, as characterized by the Water Supply Security Index (WSSI, which is the assessment value of WSS, a larger WSSI value indicates better results. In addition, the simulation results of the model can determine the change process and dynamic evolution of the WSS. Quanzhou, a city in China with serious water shortage problems, was selected as a case study. The allocation results of the current year and target year of planning demonstrated that the level of regional comprehensive WSS was significantly influenced by the capacity of water supply projects and the conditions of the natural water resources. The varying conditions of the water resources allocation results in the same year demonstrated that the allocation results and WSSI were significantly affected by reductions in precipitation, decreases in the water yield coefficient, and changes in the underlying surface.

Experimental methods of investigation of kinetics and dynamics of nuclear reactors

International Nuclear Information System (INIS)

Costa Oliveira, Jaime M.

1969-03-01

The author presents experimental methods used to study kinetic and dynamic properties of nuclear reactors. Kinetic methods aim at determining characteristic parameters of the behaviour in time of neutrons. Dynamic methods aim at establishing the relationships between the reactor behaviour and its internal and external causes (notably the measurement of transfer functions). The author proposes a classification with respect to the excitation type: periodic excitation (reactivity sinusoidal modulation, source sinusoidal modulation, periodic pulse excitation), non periodic excitation (reactivity monitoring, reactivity linear variation, reactivity variation according to any given law, removal of starting source), random excitation (random reactivity or source excitation), natural fluctuations (alpha-Rossi method, methods of reduced variance, probabilistic methods, correlation methods, spectral analysis method). He also addresses space and energy effects. Applications are reported for low power and power reactors

Building Conceptual Models of Field-Scale Uranium Reactive Transport in a Dynamic Vadose Zone-Aquifer-River System

International Nuclear Information System (INIS)

Yabusaki, Steven B.; Fang, Yilin; Waichler, Scott R.

2008-01-01

Subsurface simulation is being used to build, test, and couple conceptual process models to better understand controls on a 0.4 km by 1.0 km uranium plume that has persisted above the drinking water standard in the groundwater of the Hanford 300 Area over the last 15 years. At this site, uranium-contaminated sediments in the vadose zone and aquifer are subject to significant variations in water levels and velocities driven by the diurnal, weekly, seasonal, and episodic Columbia River stage dynamics. Groundwater flow reversals typically occur twice a day with significant exchange of river water and groundwater in the near-river aquifer. Mixing of the dilute solution chemistry of the river with the groundwater complicates the uranium sorption behavior as the mobility of U(VI) has been shown experimentally to be a function of pH, carbonate, calcium, and uranium. Furthermore, uranium mass transfer between solid and aqueous phases has been observed to be rate-limited in the context of the high groundwater velocities resulting from the river stage fluctuations and the highly transmissive sediments (hydraulic conductivities ∼1500 m/d). One- and two-dimensional vertical cross-sectional simulations of variably-saturated flow and reactive transport, based on laboratory-derived models of distributed rate mass transfer and equilibrium multicomponent surface complexation, are used to assess uranium transport at the dynamic vadose zone aquifer interface as well as changes to uranium mobility due to incursions of river water into the aquifer

A post audit and inverse modeling in reactive transport: 50 years of artificial recharge in the Amsterdam Water Supply Dunes

Science.gov (United States)

Karlsen, R. H.; Smits, F. J. C.; Stuyfzand, P. J.; Olsthoorn, T. N.; van Breukelen, B. M.

2012-08-01

SummaryThis article describes the post audit and inverse modeling of a 1-D forward reactive transport model. The model simulates the changes in water quality following artificial recharge of pre-treated water from the river Rhine in the Amsterdam Water Supply Dunes using the PHREEQC-2 numerical code. One observation dataset is used for model calibration, and another dataset for validation of model predictions. The total simulation time of the model is 50 years, from 1957 to 2007, with recharge composition varying on a monthly basis and the post audit is performed 26 years after the former model simulation period. The post audit revealed that the original model could reasonably predict conservative transport and kinetic redox reactions (oxygen and nitrate reduction coupled to the oxidation of soil organic carbon), but showed discrepancies in the simulation of cation exchange. Conceptualizations of the former model were inadequate to accurately simulate water quality changes controlled by cation exchange, especially concerning the breakthrough of potassium and magnesium fronts. Changes in conceptualization and model design, including the addition of five flow paths, to a total of six, and the use of parameter estimation software (PEST), resulted in a better model to measurement fit and system representation. No unique parameter set could be found for the model, primarily due to high parameter correlations, and an assessment of the predictive error was made using a calibration constrained Monte-Carlo method, and evaluated against field observations. The predictive error was found to be low for Na+ and Ca2+, except for greater travel times, while the K+ and Mg2+ error was restricted to the exchange fronts at some of the flow paths. Optimized cation exchange coefficients were relatively high, especially for potassium, but still within the observed range in literature. The exchange coefficient for potassium agrees with strong fixation on illite, a main clay mineral in

Reactivity of hydrogen contained in Raney nickel for ethylene hydrogenation studied by means of a tritium tracer

International Nuclear Information System (INIS)

Miyatani, Daisaku; Takeuchi, Toyosaburo.

1979-01-01

Reactivity of hydrogen contained in Raney nickel with ethylene was studied by using a tritium tracer. Hydrogen in Raney nickel was previously labeled with tritium and distinguished from hydrogen introduced during the hydrogenation reaction. The reactivity of the contained hydrogen was determined by measurement of the radioactivity of ethane produced in the hydrogenation. Ethylene reacted with hydrogen in Raney nickel for no supply of hydrogen during the hydrogenation. However, when ethylene was hydrogenated by both hydrogen in Raney nickel and introduced hydrogen, over 99% of the ethylene reacted with the introduced hydrogen and hardly reacted with the contained hydrogen. (author)

An IT-enabled supply chain model: a simulation study

Science.gov (United States)

Cannella, Salvatore; Framinan, Jose M.; Barbosa-Póvoa, Ana

2014-11-01

During the last decades, supply chain collaboration practices and the underlying enabling technologies have evolved from the classical electronic data interchange (EDI) approach to a web-based and radio frequency identification (RFID)-enabled collaboration. In this field, most of the literature has focused on the study of optimal parameters for reducing the total cost of suppliers, by adopting operational research (OR) techniques. Herein we are interested in showing that the considered information technology (IT)-enabled structure is resilient, that is, it works well across a reasonably broad range of parameter settings. By adopting a methodological approach based on system dynamics, we study a multi-tier collaborative supply chain. Results show that the IT-enabled supply chain improves operational performance and customer service level. Nonetheless, benefits for geographically dispersed networks are of minor entity.

Optimal Inventory Control with Advance Supply Information

Directory of Open Access Journals (Sweden)

Marko Jaksic

2016-09-01

Full Text Available It has been shown in numerous situations that sharing information between the companies leads to improved performance of the supply chain. We study a positive lead time periodic-review inventory system of a retailer facing stochastic demand from his customer and stochastic limited supply capacity of the manufacturer supplying the products to him. The consequence of stochastic supply capacity is that the orders might not be delivered in full, and the exact size of the replenishment might not be known to the retailer. The manufacturer is willing to share the so-called advance supply information (ASI about the actual replenishment of the retailer's pipeline order with the retailer. ASI is provided at a certain time after the orders have been placed and the retailer can now use this information to decrease the uncertainty of the supply, and thus improve its inventory policy. For this model, we develop a dynamic programming formulation, and characterize the optimal ordering policy as a state-dependent base-stock policy. In addition, we show some properties of the base-stock level. While the optimal policy is highly complex, we obtain some additional insights by comparing it to the state-dependent myopic inventory policy. We conduct the numerical analysis to estimate the in uence of the system parameters on the value of ASI. While we show that the interaction between the parameters is relatively complex, the general insight is that due to increasing marginal returns, the majority of the benets are gained only in the case of full, or close to full, ASI visibility.

Control Structures in supply chains as a way to manage unpredictable cyber-risks

DEFF Research Database (Denmark)

Sepúlveda Estay, Daniel Alberto; Khan, Omera

the application of a systemic risk analysis methodology to understand cyber risks in the supply chain. A generic supply chain is analyzed, and information flows, dynamic structures and the influence of cyber-attack on these are identified. This paper argues that a systemic approach is more efficient in detecting......Supply chain growth, and their dependence on Information Technology (IT), is making cyber risks an increasingly unmanageable threat through traditional risk assessment methods. Systemic analysis methods have been identified as alternatives to trad itional methods. This paper analyzes...

Development of an Assessment Model for Sustainable Supply Chain Management in Batik Industry

Science.gov (United States)

Mubiena, G. F.; Ma’ruf, A.

2018-03-01

This research proposes a dynamic assessment model for sustainable supply chain management in batik industry. The proposed model identifies the dynamic relationship between economic aspect, environment aspect and social aspect. The economic aspect refers to the supply chain operation reference model. The environment aspect uses carbon emissions and liquid waste as the attribute assessment, while the social aspect focus on employee’s welfare. Lean manufacturing concept was implemented as an alternative approach to sustainability. The simulation result shows that the average of sustainability score for 5 years increased from 65,3% to 70%. Future experiments will be conducted on design improvements to reach the company target on sustainability score.

Reactive Kripke semantics

CERN Document Server

Gabbay, Dov M

2013-01-01

This text offers an extension to the traditional Kripke semantics for non-classical logics by adding the notion of reactivity. Reactive Kripke models change their accessibility relation as we progress in the evaluation process of formulas in the model. This feature makes the reactive Kripke semantics strictly stronger and more applicable than the traditional one. Here we investigate the properties and axiomatisations of this new and most effective semantics, and we offer a wide landscape of applications of the idea of reactivity. Applied topics include reactive automata, reactive grammars, rea

Sub-fragmentation of structural-reactive-material casings under explosion

Science.gov (United States)

Zhang, Fan

2015-06-01

The sub-fragmentation of structural reactive material (SRM) thick-casings is to generate fine fragments during casing fragmentation under explosive loading for their efficient energy release to enhance air blast. This has been investigated using a cylindrical casing made from either rich Al-MoO3 or Al-W-based granular composites. The former composite was to study the concept of reactive hot spots where the reaction of reactive particles, which were distributed into base SRM in a fuel-rich equivalence ratio, created heat and gas products during SRM fragmentation. The expansion of these distributed hot spots initiated local fractures of the casing, leading to fine fragments. The Al-W-based composite investigated the concept of impedance mismatch, where shock dynamics at the interfaces of different impedance ingredients resulted in non-uniform, high local temperatures and stresses and late in times the dissimilar inertia resulted in different accelerations, leading to material separation and fine fragments. The casings were manufactured through both hot iso-static pressing and cold gas dynamic spray deposition. Explosion experiments were conducted in a 3 m diameter, 23 m3 cylindrical chamber for these cased charges in a casing-to-explosive mass ratio of 1.75. The results demonstrated the presence of fine fragments and more efficient fragment combustion, compared with previous results, and indicated the effectiveness of both concepts. This work was jointly funded by Defence R&D Canada and the Advanced Energetics Program of DTRA (Dr. William H. Wilson).

Mapping hypercapnia-induced cerebrovascular reactivity using BOLD MRI

Energy Technology Data Exchange (ETDEWEB)

Zande, F.H.R. van der; Hofman, P.A.M.; Backes, W.H. [Maastricht University Hospital, Department of Radiology, P.O. Box 5800, Maastricht (Netherlands)

2005-02-01

Severe carotid artery stenosis or occlusion may put patients at risk for ischaemic stroke. Reduced cerebrovascular reserve capacity is a possible indicator of an imminent ischaemic event and can be determined by assessment of cerebrovascular reactivity to a vasodilative stimulus. However, little is known about the distribution of cerebrovascular reactivity in healthy individuals. In 13 healthy volunteers, dynamic T{sub 2}{sup *} MR images, acquired at alternating inspiratory pCO{sub 2} levels, showed a high percentage of signal change in grey matter, with a strong linear correlation with end-tidal pCO{sub 2}. The mean percentages of signal change for grey and white matter were 5.9{+-}1.2% and 1.9{+-}0.5%, respectively. The mean time lag between CO{sub 2} stimulus and haemodynamic response was 15{+-}4 s for grey matter and 180{+-}12 s for white matter. Parameter mapping revealed a hemispherically symmetrical and homogeneous distribution of cerebrovascular reactivity over the entire grey matter. These findings indicate that it may be feasible to detect exhausted cerebrovascular autoregulation in patients with a compromised cerebral vasculature. (orig.)

Mapping hypercapnia-induced cerebrovascular reactivity using BOLD MRI

International Nuclear Information System (INIS)

Zande, F.H.R. van der; Hofman, P.A.M.; Backes, W.H.

2005-01-01

Severe carotid artery stenosis or occlusion may put patients at risk for ischaemic stroke. Reduced cerebrovascular reserve capacity is a possible indicator of an imminent ischaemic event and can be determined by assessment of cerebrovascular reactivity to a vasodilative stimulus. However, little is known about the distribution of cerebrovascular reactivity in healthy individuals. In 13 healthy volunteers, dynamic T 2 * MR images, acquired at alternating inspiratory pCO 2 levels, showed a high percentage of signal change in grey matter, with a strong linear correlation with end-tidal pCO 2 . The mean percentages of signal change for grey and white matter were 5.9±1.2% and 1.9±0.5%, respectively. The mean time lag between CO 2 stimulus and haemodynamic response was 15±4 s for grey matter and 180±12 s for white matter. Parameter mapping revealed a hemispherically symmetrical and homogeneous distribution of cerebrovascular reactivity over the entire grey matter. These findings indicate that it may be feasible to detect exhausted cerebrovascular autoregulation in patients with a compromised cerebral vasculature. (orig.)

Minimization of Impact from Electric Vehicle Supply Equipment to the Electric Grid Using a Dynamically Controlled Battery Bank for Peak Load Shaving

Energy Technology Data Exchange (ETDEWEB)

Castello, Charles C [ORNL

2013-01-01

This research presents a comparison of two control systems for peak load shaving using local solar power generation (i.e., photovoltaic array) and local energy storage (i.e., battery bank). The purpose is to minimize load demand of electric vehicle supply equipment (EVSE) on the electric grid. A static and dynamic control system is compared to decrease demand from EVSE. Static control of the battery bank is based on charging and discharging to the electric grid at fixed times. Dynamic control, with 15-minute resolution, forecasts EVSE load based on data analysis of collected data. In the proposed dynamic control system, the sigmoid function is used to shave peak loads while limiting scenarios that can quickly drain the battery bank. These control systems are applied to Oak Ridge National Laboratory s (ORNL) solar-assisted electric vehicle (EV) charging stations. This installation is composed of three independently grid-tied sub-systems: (1) 25 EVSE; (2) 47 kW photovoltaic (PV) array; and (3) 60 kWh battery bank. The dynamic control system achieved the greatest peak load shaving, up to 34% on a cloudy day and 38% on a sunny day. The static control system was not ideal; peak load shaving was 14.6% on a cloudy day and 12.7% on a sunny day. Simulations based on ORNL data shows solar-assisted EV charging stations combined with the proposed dynamic battery control system can negate up to 89% of EVSE load demand on sunny days.

Learning by Gaming: Supply Chain Management

OpenAIRE

Arisha, Amr; Tobail, Ayman; Crowe, John

2011-01-01

Today's third level students are of a virtual generation, where online interactive multi-player games, virtual reality and simulations are a part of everyday life, making gaming and simulation a very important catalyst in the learning process. Teaching methods have to be more innovative to help students understand the complexity of decisions within dynamic supply chain environment. Interactive simulation games have the potential to be an efficient and enjoyable means of learning. A serious in...

Comparing Cost Of New Supply Chain Designs Under Uncertainty

DEFF Research Database (Denmark)

Wæhrens, Brian Vejrum; Kristensen, Jesper; Asmussen, Jesper Normann

2016-01-01

Accounting, Operational Modelling and SCM inform decision making for new SCDs. Through four embedded cases, a gap is found between the practice of a global OEM and literature. Results shows complications when assessing SCDs due to limited understanding of the internal activity costs, supply chain dynamics...

Optimal allocation of the limited oral cholera vaccine supply between endemic and epidemic settings.

Science.gov (United States)

Moore, Sean M; Lessler, Justin

2015-10-06

The World Health Organization (WHO) recently established a global stockpile of oral cholera vaccine (OCV) to be preferentially used in epidemic response (reactive campaigns) with any vaccine remaining after 1 year allocated to endemic settings. Hence, the number of cholera cases or deaths prevented in an endemic setting represents the minimum utility of these doses, and the optimal risk-averse response to any reactive vaccination request (i.e. the minimax strategy) is one that allocates the remaining doses between the requested epidemic response and endemic use in order to ensure that at least this minimum utility is achieved. Using mathematical models, we find that the best minimax strategy is to allocate the majority of doses to reactive campaigns, unless the request came late in the targeted epidemic. As vaccine supplies dwindle, the case for reactive use of the remaining doses grows stronger. Our analysis provides a lower bound for the amount of OCV to keep in reserve when responding to any request. These results provide a strategic context for the fulfilment of requests to the stockpile, and define allocation strategies that minimize the number of OCV doses that are allocated to suboptimal situations. © 2015 The Authors.

Accelerating the transition towards sustainability dynamics into supply chain relationship management and governance structures

DEFF Research Database (Denmark)

Govindan, Kannan; Seuring, Stefan; Zhu, Qinghua

2016-01-01

successful futures by maintaining a healthy balance among economic, environmental, and social resources/dimensions. Consequently, some organizations have begun to integrate these dimensions in recent years. Researchers and practitioners are also working to accelerate the transition for more equitable......, sustainable, post-fossil carbon societies by working with all relevant stakeholders. This Special Volume of Journal of Cleaner Production is focused upon on diverse types of supply chain relationships, governance mechanisms, and innovations, which can foster effective and efficient sustainable supply chain...... management. This volume is comprised of twenty-seven articles and a book review. Fifteen of the articles address the supply chain relationships domain, while five focus primarily upon governance, five upon innovation, and two on relationships and governance. However, there is a huge potential to further...

The Everyday Emotional Experience of Adults with Major Depressive Disorder: Examining Emotional Instability, Inertia, and Reactivity

Science.gov (United States)

Thompson, Renee J.; Mata, Jutta; Jaeggi, Susanne M.; Buschkuehl, Martin; Jonides, John; Gotlib, Ian H.

2013-01-01

Investigators have begun to examine the temporal dynamics of affect in individuals diagnosed with Major Depressive Disorder (MDD), focusing on instability, inertia, and reactivity of emotion. How these dynamics differ between individuals with MDD and healthy controls have not before been examined in a single study. In the present study, 53 adults with MDD and 53 healthy adults carried hand-held electronic devices for approximately seven days and were prompted randomly eight times per day to report their levels of current negative affect (NA), positive affect (PA), and the occurrence of significant events. In terms of NA, compared with healthy controls, depressed participants reported greater instability and greater reactivity to positive events, but comparable levels of inertia and reactivity to negative events. Neither average levels of NA nor NA reactivity to, frequency or intensity of, events accounted for the group difference in instability of NA. In terms of PA, the MDD and control groups did not differ significantly in their instability, inertia, or reactivity to positive or negative events. These findings highlight the importance of emotional instability in MDD, particularly with respect to NA, and contribute to a more nuanced understanding of the everyday emotional experiences of depressed individuals. PMID:22708886

Impact of market forces on security of supply; Markedsgoerelse af forsyningssikkerhed

Energy Technology Data Exchange (ETDEWEB)

Klinge Jakobsen, H.; Kromann, M.T.; Hoermann, M. (and others)

2010-05-15

by putting power sufficiency on the market. In the model, these savings quantified to 15-20 billion DKK annually for the Nordic countries and Germany (just over 1 oere per kWh). The savings are primarily due to avoiding keeping the production capacity in reserve. Instead, one allows the market to generate a direct incentive to consumers, or their utilities, to invest in technology that gives more flexibility and dynamics to the system. Moreover, the likelihood is reduced that a too high level of security of supply is kept through conservative planning. Much of the investment in the dynamic power system is not profitable only for the sake of security. Increased activation of consumption resources has a larger value for power systems based on wind power and thermal generation, rather than for the hydro-intensive northern Europe. Developments to activate consumption reserves are already under way within the current market environment. Security of supply, increased demand for integration of fluctuating wind power and the desire for a more efficient use of both energy and capital resources pull in the same direction relative to the dynamic energy system. (ln)

Experimental Application of an Advanced Separation Process for NOM Removal from Surface Drinking Water Supply

Directory of Open Access Journals (Sweden)

Arianna Callegari

2017-10-01

Full Text Available Natural organic matter (NOM in drinking water supplies significantly impacts on water supply quality and treatment, due to observed reactivity with many dissolved and particulate species. Several technologies are used nowadays to remove NOM from the water supply. The evolution of water-related directives, and progressively more restrictive standards for drinking water, however, call for the investigation of advanced, more efficient, and cost-effective water treatment processes. This paper contains a brief overview on the state-of-the-art methods for NOM removal from supply waters, and describes the experimental application of an advanced technology, tested and validated at the pilot scale on the water supply source of a town in Poland. The process allowed significant removal of natural organic matter (about 50% as Dissolved Organic Carbon and turbidity (from 50% to 90%, however, these results requested significant additions of powdered activated carbon. The key to success of this type of process is a correct setup with the identification of optimal types and dosages of reagents. Based on the results of the tests conducted it is foreseeable that this technology could be used onsite, not only for removal of NOM, but also of other hard-to-tackle pollutants potentially contained in the freshwater supply and not presently considered.

Reactive Force Field for Liquid Hydrazoic Acid with Applications to Detonation Chemistry

Science.gov (United States)

Furman, David; Dubnikova, Faina; van Duin, Adri; Zeiri, Yehuda; Kosloff, Ronnie

The development of a reactive force field (ReaxFF formalism) for Hydrazoic acid (HN3), a highly sensitive liquid energetic material, is reported. The force field accurately reproduces results of density functional theory (DFT) calculations. The quality and performance of the force field are examined by detailed comparison with DFT calculations related to uni, bi and trimolecular thermal decomposition routes. Reactive molecular dynamics (RMD) simulations are performed to reveal the initial chemical events governing the detonation chemistry of liquid HN3. The outcome of these simulations compares very well with recent results of tight-binding DFT molecular dynamics and thermodynamic calculations. Based on our RMD simulations, predictions were made for the activation energies and volumes in a broad range of temperatures and initial material compressions. Work Supported by The Center of Excellence for Explosives Detection, Mitigation and Response, Department of Homeland Security.

Reactivation or reinfection in adult tuberculosis: Is that the question?

Science.gov (United States)

Cardona, Pere-Joan

2016-12-01

Looking at the chapter on "natural history" in any tuberculosis (TB) reference book, there is a kind of certainty regarding TB in adults. That is the concept of "post-primary" TB described as the reactivation of dormant bacilli hidden in an old lesion developed during infancy due to a type of local immunosuppression. Intriguingly, this concept involves at least two major uncertainties: how can dormant bacilli remain for such a long period, almost a lifetime, in an old lesion, taking into account granuloma dynamism; and what sort of local immunosuppression is the one that facilitates reactivation? The controversy between reactivation and exogenous reinfection as the cause of active TB started very soon in TB research. Interestingly, this "balance" was disturbed in the 1960s when the "Unitary Concept" became very successful in supporting the reactivation dogma. The "Unitary Concept" was mainly based on the data of tuberculin surveillance during the pre-antibiotic era as well as the data obtained from experimental modelling in animals. At the same time, the "Three-risks model" appeared to explain the relationship between the risk of infection and TB incidence, granting reinfection a key role in adult TB together with primary infection. This role was reinforced by the studies of recurrence based on molecular epidemiology, and a better knowledge of the immune response, granuloma dynamics, and lung physiology. Now it is a matter of taking it into account when designing new prophylactic and therapeutic strategies and also reflecting it in text books to better illustrate to our students. Copyright © 2016 Asian-African Society for Mycobacteriology. Published by Elsevier Ltd. All rights reserved.

Factors influencing long term dynamics of health care supply and demand

NARCIS (Netherlands)

Smits, M.T.; Roos, E.; Pries-Heje, J.; Chiasson, M.; Wareham, J.; Busquets, X.; Valor, J.

2012-01-01

Governments and other policy makers use long-term planning models to support workforce planning decisions for regulating care markets and to ensure accurate balancing between care supply and demand. Our aim is to understand long-term effects of workforce planning decisions on care markets, in order

The Knowledge Supply Model: A Framework for Developing Education and Training in the New Economy.

Science.gov (United States)

Burton-Jones, Alan

2001-01-01

The knowledge supply model depicts the dynamics of change and patterns of knowledge supply and demand in economic sectors. Its elements are knowledge characteristics, organizational specificity of knowlwege, value of knowledge, and level of suppliers' knowledge. Learning organizations can use the model to tailor products and servers to knowledge…

Reactive molecular dynamics simulations of the mechanical properties of various phosphorene allotropes

Science.gov (United States)

Le, Minh-Quy

2018-05-01

Although various phosphorene allotropes have been theoretically predicted to be stable at 0 K, the mechanical properties and fracture mechanism at room temperature remain unclear for many of them. We investigate through reactive molecular dynamics simulations at room temperature the mechanical properties of phosphorene allotropes including: five sheets with hexagonal structures (β-, γ-, δ-, θ-, and α-phosphorene), one sheet with 4-8 membered rings (4-8-P), and two sheets with 5-7 membered rings. High, moderate and slight anisotropies in their mechanical properties are observed, depending on their crystal structures. Their Young’s moduli and tensile strength are approximately in the range from 7.3% through 25%, and from 8.6% through 22% of those of graphene, respectively. At the early stage of fracture, eye-shaped cracks are formed by local bond breaking and perpendicular to the tensile direction in hexagonal and 4-8-P sheets. Complete fractures take place with straight cracks in these hexagonal sheets under tension along the zigzag direction and under tension along the square edge direction in the 4-8-P sheet. Crack meandering and branching are observed during the tension of α-, β-, and γ-phosphorene along the armchair direction; and along the square diagonal direction in the 4-8-P sheet. Under uniaxial tension of two phosphorene sheets with 5-7 atom rings, 12 and 10 membered rings are formed by merging two neighbor heptagons, and a heptagon and its neighbor pentagon, respectively. These 12 and 10 membered rings coalesce subsequently, causing the failure of these two sheets. The results are of great importance in the design of these novel phosphorene allotropes.

E-beam high voltage switching power supply

Science.gov (United States)

Shimer, Daniel W.; Lange, Arnold C.

1997-01-01

A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360.degree./n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load.

E-beam high voltage switching power supply

International Nuclear Information System (INIS)

Shimer, D.W.; Lange, A.C.

1997-01-01

A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360 degree/n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load. 7 figs

Reactive power compensation. System service - line quality. 2. ed.; Blindleistungskompensation. Systemdienstleistung - Netzqualitaet

Energy Technology Data Exchange (ETDEWEB)

Grosse-Gehling, Martin; Just, Wolfgang; Reese, Juergen; Schlabbach, Juergen

2013-11-01

Reactive power compensation is playing an increasingly important role as the need for an efficient use of operating equipment and power grids continues to grow. This book presents the fundamentals of reactive power compensation in low and medium voltage grids, offering a wealth of application and calculation examples that will further the reader's understanding of the following topics: 1. design, dimensioning and operation of capacitors and capacitor installations; 2. long-term stability and ageing of capacitor installations; 3. use of passive and active filters; 4. improvement of voltage quality by means of filters and capacitor installations; 5. provision of reactive power compensation by means of power electronics; 6. costs and economic efficiency of reactive power compensation and filter equipment; 7. considerations from the viewpoint of the power supply industry; price regulations; 8. information requirements concerning PCB-containing capacitors; 9. climate protection and energy efficiency through reactive power compensation; 10. technical connection requirements and guidelines; 11. special technical issues concerning the use of reactive power compensation installations. [German] Die Blindleistungskompensation gewinnt angesichts der Notwendigkeit zur erhoehten Ausnutzung der Betriebsmittel und Netze zunehmend an Bedeutung. In diesem Buch werden die Grundlagen der Blindleistungskompensation in Nieder- und Mittelspannungsnetzen beschrieben und folgende Themen anhand zahlreicher Anwendungs- und Berechnungsbeispiele vertieft: 1. Aufbau, Auslegung und Betrieb von Kondensatoren und Kondensatoranlagen, 2. Langzeitstabilitaet und Alterung von Kondensatoranlagen, 3. Einsatz passiver und aktiver Filter, 4. Verbesserung der Spannungsqualitaet durch Filter und Kondensatoranlagen, 5. Blindleistungsbereitstellung mit Leistungselektronik, 6. Kosten und Wirtschaftlichkeit von Kompensations- und Filteranlagen, 7. Elektrizitaetswirtschaftliche Betrachtungen

Applications of Molecular Dynamics, Monte Carlo and Metadynamics Simulations Using ReaxFF Reactive Force Fields to Fluid/Solid Interfaces

Science.gov (United States)

Raju, Muralikrishna

The interaction of dense fluids (water, polar organic solvents, room temperature ionic liquids, etc.) with solid substrates controls many chemical processes encountered in nature and industry. The key features of fluid-solid interfaces (FSIs) are the high mobility and often reactivity of the fluid phase, and the structural control provided by the solid phase. In this dissertation we apply molecular modeling methods to study FSIs in the following systems: 1. Dissociation of water on titania surfaces. We studied the adsorption and dissociation of water at 300 K on the following TiO2 surfaces: anatase (101), (100), (112), (001) and rutile (110) at various water coverages, using a recently developed ReaxFF reactive force field. The molecular and dissociative adsorption configurations predicted by ReaxFF for various water coverages agree with previous theoretical studies and experiment. 2. Mechanisms of Oriented Attachment in TiO2 nanocrystals. Oriented attachment (OA) of nanocrystals is now widely recognized as a key process in the solution-phase growth of hierarchical nanostructures. However, the microscopic origins of OA remain unclear. Using the same ReaxFF Ti/O/H reactive force field employed in the previous study, we perform molecular dynamics simulations to study the aggregation of various titanium dioxide (anatase) nanocrystals in vacuum and humid environments. 3. Li interactions in carbon based materials. Graphitic carbon is still the most ubiquitously used anode material in Li-ion batteries. In spite of its ubiquity, there are few theoretical studies that fully capture the energetics and kinetics of Li in graphite and related nanostructures at experimentally relevant length/time-scales and Li-ion concentrations. In this study we describe development and application of a ReaxFF reactive force field to describe Li interactions in perfect and defective carbon based materials using atomistic simulations. We develop force-field parameters for Li-C systems using van

Modeling of flow and reactive transport in IPARS

KAUST Repository

Wheeler, Mary Fanett

2012-03-11

In this work, we describe a number of efficient and locally conservative methods for subsurface flow and reactive transport that have been or are currently being implemented in the IPARS (Integrated Parallel and Accurate Reservoir Simulator). For flow problems, we consider discontinuous Galerkin (DG) methods and mortar mixed finite element methods. For transport problems, we employ discontinuous Galerkin methods and Godunov-mixed methods. For efficient treatment of reactive transport simulations, we present a number of state-of-the-art dynamic mesh adaptation strategies and implementations. Operator splitting approaches and iterative coupling techniques are also discussed. Finally, numerical examples are provided to illustrate the capability of IPARS to treat general biogeochemistry as well as the effectivity of mesh adaptations with DG for transport. © 2012 Bentham Science Publishers. All rights reserved.

Performance of the main ring magnet power supply of the KEK 12 GeV proton synchrotron

International Nuclear Information System (INIS)

Sato, H.; Sueno, T.; Toyama, T.; Mikawa, Ml; Toda, M.; Matsumoto, S.; Nakano, M.

1992-01-01

The main ring magnet power supply of the KEK 12 GeV PS consists of several twelve-pulse thyristor rectifiers with dc filters, of two reactive power compensators with tuned ac harmonic filters and of an analog and digital hybrid control system. In order to obtain well defined parameters-such as absolute precision of beam energy, stable beam position, tracking between focusing and bending fields to fix the betatron tune, stable acquisition of extracted beam spill etc.-one wants to operate this large pulsed power supply with high current reproducibility and low residual current ripple. In this paper, several stabilization techniques are applied in order to meet these requirements

ADSORPTION OF THE DYE REACTIVE BLUE 5G IN RETORTED SHALE

Directory of Open Access Journals (Sweden)

R. Lambrecht

2015-03-01

Full Text Available Abstract In this study the influence of the volumetric flow rate and feed concentration was investigated for the adsorption of the reactive dye Blue 5G. Experiments were carried out in a bed packed with retorted shale, at 30 ºC. The ranges investigated were flow rate 2 -10 mL/min and the feed concentration 13-105 mg/L. Mathematical models were used to represent the dynamic sorption. The double resistance model considers the effects of the axial dispersion and the mass transfer resistance of the external film and inside the particles. As a result, the mass transfer coefficient of the external film and the internal mass transfer coefficient were estimated. The Thomas model was used to simulate the experimental data. In this model the fitted parameter was the adsorption kinetic constant. The first model provided an acceptable representation of the dynamic uptake of the reactive dye Blue 5G.

Augmenting Transport versus Increasing Cold Storage to Improve Vaccine Supply Chains

Science.gov (United States)

Haidari, Leila A.; Connor, Diana L.; Wateska, Angela R.; Brown, Shawn T.; Mueller, Leslie E.; Norman, Bryan A.; Schmitz, Michelle M.; Paul, Proma; Rajgopal, Jayant; Welling, Joel S.; Leonard, Jim; Chen, Sheng-I; Lee, Bruce Y.

2013-01-01

Background When addressing the urgent task of improving vaccine supply chains, especially to accommodate the introduction of new vaccines, there is often a heavy emphasis on stationary storage. Currently, donations to vaccine supply chains occur largely in the form of storage equipment. Methods This study utilized a HERMES-generated detailed, dynamic, discrete event simulation model of the Niger vaccine supply chain to compare the impacts on vaccine availability of adding stationary cold storage versus transport capacity at different levels and to determine whether adding stationary storage capacity alone would be enough to relieve potential bottlenecks when pneumococcal and rotavirus vaccines are introduced by 2015. Results Relieving regional level storage bottlenecks increased vaccine availability (by 4%) more than relieving storage bottlenecks at the district (1% increase), central (no change), and clinic (no change) levels alone. Increasing transport frequency (or capacity) yielded far greater gains (e.g., 15% increase in vaccine availability when doubling transport frequency to the district level and 18% when tripling). In fact, relieving all stationary storage constraints could only increase vaccine availability by 11%, whereas doubling the transport frequency throughout the system led to a 26% increase and tripling the frequency led to a 30% increase. Increasing transport frequency also reduced the amount of stationary storage space needed in the supply chain. The supply chain required an additional 61,269L of storage to relieve constraints with the current transport frequency, 55,255L with transport frequency doubled, and 51,791L with transport frequency tripled. Conclusions When evaluating vaccine supply chains, it is important to understand the interplay between stationary storage and transport. The HERMES-generated dynamic simulation model showed how augmenting transport can result in greater gains than only augmenting stationary storage and can reduce

Augmenting transport versus increasing cold storage to improve vaccine supply chains.

Science.gov (United States)

Haidari, Leila A; Connor, Diana L; Wateska, Angela R; Brown, Shawn T; Mueller, Leslie E; Norman, Bryan A; Schmitz, Michelle M; Paul, Proma; Rajgopal, Jayant; Welling, Joel S; Leonard, Jim; Chen, Sheng-I; Lee, Bruce Y

2013-01-01

When addressing the urgent task of improving vaccine supply chains, especially to accommodate the introduction of new vaccines, there is often a heavy emphasis on stationary storage. Currently, donations to vaccine supply chains occur largely in the form of storage equipment. This study utilized a HERMES-generated detailed, dynamic, discrete event simulation model of the Niger vaccine supply chain to compare the impacts on vaccine availability of adding stationary cold storage versus transport capacity at different levels and to determine whether adding stationary storage capacity alone would be enough to relieve potential bottlenecks when pneumococcal and rotavirus vaccines are introduced by 2015. Relieving regional level storage bottlenecks increased vaccine availability (by 4%) more than relieving storage bottlenecks at the district (1% increase), central (no change), and clinic (no change) levels alone. Increasing transport frequency (or capacity) yielded far greater gains (e.g., 15% increase in vaccine availability when doubling transport frequency to the district level and 18% when tripling). In fact, relieving all stationary storage constraints could only increase vaccine availability by 11%, whereas doubling the transport frequency throughout the system led to a 26% increase and tripling the frequency led to a 30% increase. Increasing transport frequency also reduced the amount of stationary storage space needed in the supply chain. The supply chain required an additional 61,269L of storage to relieve constraints with the current transport frequency, 55,255L with transport frequency doubled, and 51,791L with transport frequency tripled. When evaluating vaccine supply chains, it is important to understand the interplay between stationary storage and transport. The HERMES-generated dynamic simulation model showed how augmenting transport can result in greater gains than only augmenting stationary storage and can reduce stationary storage needs.

Study on offshore wind farm integration mode and reactive power compensation

Energy Technology Data Exchange (ETDEWEB)

Bian, Xiaoyan; Hong, Lijun; Fu, Yang [Shanghai Univ. of Electrical Power (China). Power and Automation Engineering Dept.

2013-07-01

Two typical offshore wind farm grid-connected modes are introduced and dynamic characteristics under their modes are compared from the simulation by PSS/E. The result shows that offshore wind farm with VSC-HVDC has better dynamic characteristics on fault isolation, reactive power compensation, and fault ride through ability. In addition, STATCOM has been applied to the offshore wind farm, the simulation results indicates that it can improve the bus voltage stability in fault and maintain the voltage level under a small perturbation.

EVALUATING DEGREE OF ACTIVE POWER LOSSES REDUCTION IN THE ELECTRIC POWER LINES WITH REACTIVE POWER COMPENSATION

Directory of Open Access Journals (Sweden)

V. N. Radkevich

2016-01-01

Full Text Available The paper considers evaluation procedure for the degree of active power losses reduction in the power transmission lines under 1 kV and 6–10 kV of the systems of electric power supply of industrial enterprises with compensating installations mounted at the side of the customer. The capacitor installations conform to the applied voltage level and factor in dielectric losses in the capacitors. The voltage at the compensating device terminal changes from 0.95 to 1.05 of the capacitors nominal voltage. The study did not account for reactive power losses in the line, nor did it for its charge capacity, conditioned by relative shortness of the cable lines generally operating in the mains of industrial enterprises. For this reason, the quantities of reactive power being consumed and generated by the transmission line are negligible and do not significantly affect the reactive power flux. The researchers obtain functional relations that allow estimating the degree of power loss reduction in the transmission line factoring in its explicit initial data. They perform mathematical analysis of the obtained functional relations and study the function by means of derivatives. The function extremum points are found as well as the intervals of its increment and decrement. A graphical research of the obtained functional relation is performed. It is ascertained that reduction of the active power losses is contingent on the line and the capacitor-installation engineering factors, the electrical energy consumer reactive load value as well as the voltage applied to the capacitor installation. The functional relations presented in the article can be employed in scoping calculation necessary for decision making on the reactive power compensation in systems of the industrial facilities electric power supply. Their account will allow a more accurate estimate of technical and economic effect of the capacitor bank installation in the electrical mains under 1 kV and 6�

Digital reactivity meter

International Nuclear Information System (INIS)

Akkus, B.; Anac, H.; Alsan, S.; Erk, S.

1991-01-01

Nowadays, various digital methods making use of microcomputers for neutron detector signals and determining the reactivity by numerical calculations are used in reactor control systems in place of classical reactivity meters. In this work, a calculation based on the ''The Time Dependent Transport Equation'' has been developed for determining the reactivity numerically. The reactivity values have been obtained utilizing a computer-based data acquisition and control system and compared with the analog reactivity meter values as well as the values calculated from the ''Inhour Equation''

Dynamic replenishment, production, and pricing decisions in the face of supply disruption and random price-sensitive demand

NARCIS (Netherlands)

Zhu, Stuart X.

2013-01-01

We study a joint decision problem for replenishment, production, pricing strategies in the face of both supply and demand uncertainties. The supply of the raw material suffers from a potential supply disruption while the demand for the finished goods is price-sensitive and random. We assume that the

Price changing and inventory sharing in supply chain management

Directory of Open Access Journals (Sweden)

Kristina Šorić

2017-01-01

Full Text Available The main task of supply chain management is to balance efficiency and effectiveness. Numerous operational management strategies are used to make a supply chain efficient, one such is inventory management. In this paper, we will consider a particular part of a supply chain consisting comprising a manufacturer and a retailer with the goal of minimizing associated inventory costs. We will focus on an inventory of final products determined as the difference between supply and demand and are expressed as a function of price, inflation rate and change in inflation rate resulting in the possible speculations. The manufacturer’s inventory cost is a function of these same variables, with the retailer’s inventory cost having the same function in addition to the margin. The problem is formulated as a dynamic game to share the speculation problem. The optimization problems to be solved are optimal control theory problems with objective functions in the form of integral functional with the integrand depending on the state function and its first and second derivative.

Decision-Making for Supply Chain Integration Supply Chain Integration

CERN Document Server

Lettice, Fiona; Durowoju, Olatunde

2012-01-01

Effective supply chain integration, and the tight co-ordination it creates, is an essential pre-requisite for successful supply chain management.  Decision-Making for Supply Chain Integration is a practical reference on recent research in the area of supply chain integration focusing on distributed decision-making problems. Recent applications of various decision-making tools for integrating supply chains are covered including chapters focusing on: •Supplier selection, pricing strategy and inventory decisions in multi-level supply chains, •RFID-enabled distributed decision-making, •Operational risk issues and time-critical decision-making for sensitive logistics nodes, Modelling end to end processes to improve supply chain integration, and •Integrated systems to improve service delivery and optimize resource use. Decision-Making for Supply Chain Integration provides an insight into the tools and methodologies of this field with support from real-life case studies demonstrating successful application ...

Integrating Dynamic Pricing and Replenishment Decisions Under Supply Capacity Uncertainty

OpenAIRE

Qi Feng

2010-01-01

This paper examines an integrated decision-making process regarding pricing for uncertain demand and sourcing from uncertain supply, which are often studied separately in the literature. Our analysis of the integrated system suggests that the base stock list price policy fails to achieve optimality even under deterministic demand. Instead, the optimal policy is characterized by two critical values: a reorder point and a target safety stock. Under this policy, a positive order is issued if and...

Comprehensive Reactive Power Support of DFIG Adapted to Different Depth of Voltage Sags

Directory of Open Access Journals (Sweden)

Yangwu Shen

2017-06-01

Full Text Available The low voltage ride-through (LVRT capability of the doubly-fed induction generator (DFIG significantly impacts upon the integration of wind power into the power grid. This paper develops a novel comprehensive control strategy to enhance the LVRT and reactive power support capacities of the DFIG by installing the energy storage system (ESS. The ESS is connected to the DC-link capacitor of the DFIG and used to regulate the DC-link voltage during normal or fault operations. The unbalanced power between the captured wind power and the power injected to the grid during the transient process is absorbed or compensated by the ESS. The rotor-side converter (RSC is used to control the maximum power production and the grid-side converter (GSC is used to control the reactive power before participating in the voltage support. When the supply voltage continues to drop, the rotor speed is increased by controlling the RSC to realize the LVRT capability and help the GSC further enhance the reactive power support capability. The capacity of the GSC is dedicated to injecting the reactive power to the grid. An auxiliary transient pitch angle controller is proposed to protect the generator’s over speed. Both RSC and GSC act as reactive power sources to further enhance the voltage support capability with serious voltage sags. Simulations based on a single-machine infinite-bus power system verify the effectiveness of the developed comprehensive control strategy.

A formal modeling approach for supply chain event management

NARCIS (Netherlands)

Liu, R.; Kumar, Akhil; Aalst, van der W.M.P.

2007-01-01

As supply chains become more dynamic, there is a need for a sense-and-respond capability to react to events in a real-time manner. In this paper, we propose Petri nets extended with time and color (to represent case data) as a formalism for managing events. We designed seven basic patterns to

The Bullwhip Effect: Concretization of Entropic Information Dissipation in Supply Chain Systems

Directory of Open Access Journals (Sweden)

Tarik Saikouk

2012-08-01

Full Text Available Supply chains represent complex and dynamic systems that incorporate autonomous firms interacting with one another to fulfill a common goal, while insuring their own ones. These firms’ behaviors are considered to be non-linear and sometimes unpredictable. This makes information transfer in the supply chain complex and causes instability when information transferred is incomplete or incorrect. This instability is characterized by the Bullwhip Effect that represents concretization of entropy, namely the degree of disorder within a system. In this paper we develop a new analytical approach assuming that the bullwhip effect is a consequence of the entropy of the supply chain system that is represented by information dissipation.

Magnet power supply system for the ISABELLE half-cell prototype

International Nuclear Information System (INIS)

Nawrocky, R.J.

1977-01-01

Due to stringent requirements on the spatial harmonic content of ISABELLE's magnetic field, the magnet power supplies for the half-cell prototype must be dynamically accurate and stable to within 0.01% of their full-scale rating. Depending on the application, the full-scale current of various units comprising the system ranges from +-50 A to 4000 A. The system, as constructed is fully controllable and programmable either manually or with a control computer. The magnet power supply system described was constructed and interconnected with the half-cell computer control equipment. A number of power supply units were tested with inductive test loads in both the manual and the computer control modes. Test results on stability and speed of response indicate that all systems perform according to specifications

Distributed multi-agent scheme for reactive power management with renewable energy

International Nuclear Information System (INIS)

Rahman, M.S.; Mahmud, M.A.; Pota, H.R.; Hossain, M.J.

2014-01-01

Highlights: • A distributed multi-agent scheme is proposed to enhance the dynamic voltage stability. • A control agent is designed where control actions are performed through PI controller. • Proposed scheme is compared with the conventional approach with DSTATCOM. • Proposed scheme adapts the capability of estimation and control under various operating conditions. - Abstract: This paper presents a new distributed multi-agent scheme for reactive power management in smart coordinated distribution networks with renewable energy sources (RESs) to enhance the dynamic voltage stability, which is mainly based on controlling distributed static synchronous compensators (DSTATCOMs). The proposed control scheme is incorporated in a multi-agent framework where the intelligent agents simultaneously coordinate with each other and represent various physical models to provide information and energy flow among different physical processes. The reactive power is estimated from the topology of distribution networks and with this information, necessary control actions are performed through the proposed proportional integral (PI) controller. The performance of the proposed scheme is evaluated on a 8-bus distribution network under various operating conditions. The performance of the proposed scheme is validated through simulation results and these results are compared to that of conventional PI-based DSTATCOM control scheme. From simulation results, it is found that the distributed MAS provides excellence performance for improving voltage profiles by managing reactive power in a smarter way

The effect of core configuration on temperature coefficient of reactivity in IRR-1

Energy Technology Data Exchange (ETDEWEB)

Bettan, M.; Silverman, I.; Shapira, M.; Nagler, A. [Soreq Nuclear Research Center, Yavne (Israel)

1997-08-01

Experiments designed to measure the effect of coolant moderator temperature on core reactivity in an HEU swimming pool type reactor were performed. The moderator temperature coefficient of reactivity ({alpha}{sub {omega}}) was obtained and found to be different in two core loadings. The measured {alpha}{sub {omega}} of one core loading was {minus}13 pcm/{degrees}C at the temperature range of 23-30{degrees}C. This value of {alpha}{sub {omega}} is comparable to the data published by the IAEA. The {alpha}{sub {omega}} measured in the second core loading was found to be {minus}8 pcm/{degrees}C at the same temperature range. Another phenomenon considered in this study is core behavior during reactivity insertion transient. The results were compared to a core simulation using the Dynamic Simulator for Nuclear Power Plants. It was found that in the second core loading factors other than the moderator temperature influence the core reactivity more than expected. These effects proved to be extremely dependent on core configuration and may in certain core loadings render the reactor`s reactivity coefficient undesirable.

Port supply chain integration : analyzing biofuel supply chains

NARCIS (Netherlands)

Stevens, Leonie C. E.; Vis, Iris F. A.

2016-01-01

This paper focuses on port supply chain integration to strengthen operational and business performance. We provide a structured and comprehensive method to enable port supply chain integration and demonstrate its applicability to the biofuel supply chain. We define the value proposition, role,

Plant dynamics analyses of fast reactor concept: RAPID-A without any control rod

International Nuclear Information System (INIS)

Kambe, Mitsuru

1996-01-01

Plant dynamics analyses of a fast reactor concept RAPID-A without any control rod have been demonstrated in case of reactor startup and sudden change of the primary flow rate. RAIP-A concept involves Lithium Expansion Module (LEM) for inherent reactivity feedback, Lithium Injection Module (LIM) for inherent ultimate shutdown and Lithium Release Module (LRM) for automated reactor startup. LEM consists of Quick-LEM and Slow-LEM. Slow-LEM provides with moderate reactivity addition as decreasing temperature. Quick-LEM assures quick negative reactivity feedback as increasing temperature. Plant dynamics analyses revealed that reactor power is nearly proportional to the primary flow rate even if the flow rate increases suddenly. Fully automated reactor startup from the subcritical condition has been attempted by inserting reactivity at a constant rate by LRM. Allowable rate of reactivity addition has been obtained in respect to Quick-LEM reactivity worth. (author)

Reactive power interconnection requirements for PV and wind plants : recommendations to NERC.

Energy Technology Data Exchange (ETDEWEB)

McDowell, Jason (General Electric, Schenectady, NY); Walling, Reigh (General Electric, Schenectady, NY); Peter, William (SunPower, Richmond, CA); Von Engeln, Edi (NV Energy, Reno, NV); Seymour, Eric (AEI, Fort Collins, CO); Nelson, Robert (Siemens Wind Turbines, Orlando, FL); Casey, Leo (Satcon, Boston, MA); Ellis, Abraham; Barker, Chris. (SunPower, Richmond, CA)

2012-02-01

Voltage on the North American bulk system is normally regulated by synchronous generators, which typically are provided with voltage schedules by transmission system operators. In the past, variable generation plants were considered very small relative to conventional generating units, and were characteristically either induction generator (wind) or line-commutated inverters (photovoltaic) that have no inherent voltage regulation capability. However, the growing level of penetration of non-traditional renewable generation - especially wind and solar - has led to the need for renewable generation to contribute more significantly to power system voltage control and reactive power capacity. Modern wind-turbine generators, and increasingly PV inverters as well, have considerable dynamic reactive power capability, which can be further enhanced with other reactive support equipment at the plant level to meet interconnection requirements. This report contains a set of recommendations to the North-America Electricity Reliability Corporation (NERC) as part of Task 1-3 (interconnection requirements) of the Integration of Variable Generation Task Force (IVGTF) work plan. The report discusses reactive capability of different generator technologies, reviews existing reactive power standards, and provides specific recommendations to improve existing interconnection standards.

Toddler inhibited temperament, maternal cortisol reactivity and embarrassment, and intrusive parenting.

Science.gov (United States)

Kiel, Elizabeth J; Buss, Kristin A

2013-06-01

The relevance of parenting behavior to toddlers' development necessitates a better understanding of the influences on parents during parent-child interactions. Toddlers' inhibited temperament may relate to parenting behaviors, such as intrusiveness, that predict outcomes later in childhood. The conditions under which inhibited temperament relates to intrusiveness, however, remain understudied. A multimethod approach would acknowledge that several levels of processes determine mothers' experiences during situations in which they witness their toddlers interacting with novelty. As such, the current study examined maternal cortisol reactivity and embarrassment about shyness as moderators of the relation between toddlers' inhibited temperament and maternal intrusive behavior. Participants included 92 24-month-old toddlers and their mothers. Toddlers' inhibited temperament and maternal intrusiveness were measured observationally in the laboratory. Mothers supplied saliva samples at the beginning of the laboratory visit and 20 minutes after observation. Maternal cortisol reactivity interacted with inhibited temperament in relation to intrusive behavior, such that mothers with higher levels of cortisol reactivity were observed to be more intrusive with more highly inhibited toddlers. Embarrassment related to intrusive behavior as a main effect. These results highlight the importance of considering child characteristics and psychobiological processes in relation to parenting behavior. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Incorporation of a Wind Generator Model into a Dynamic Power Flow Analysis

Directory of Open Access Journals (Sweden)

Angeles-Camacho C.

2011-07-01

Full Text Available Wind energy is nowadays one of the most cost-effective and practical options for electric generation from renewable resources. However, increased penetration of wind generation causes the power networks to be more depend on, and vulnerable to, the varying wind speed. Modeling is a tool which can provide valuable information about the interaction between wind farms and the power network to which they are connected. This paper develops a realistic characterization of a wind generator. The wind generator model is incorporated into an algorithm to investigate its contribution to the stability of the power network in the time domain. The tool obtained is termed dynamic power flow. The wind generator model takes on account the wind speed and the reactive power consumption by induction generators. Dynamic power flow analysis is carried-out using real wind data at 10-minute time intervals collected for one meteorological station. The generation injected at one point into the network provides active power locally and is found to reduce global power losses. However, the power supplied is time-varying and causes fluctuations in voltage magnitude and power fl ows in transmission lines.

Advective and diffusive contributions to reactive gas transport during pyrite oxidation in the unsaturated zone

DEFF Research Database (Denmark)

Binning, Philip John; Postma, Diederik Jan; Russel, T.F.

2007-01-01

Pyrite oxidation in unsaturated mine waste rock dumps and soils is limited by the supply of oxygen from the atmosphere. In models, oxygen transport through the subsurface is often assumed to be driven by diffusion. However, oxygen comprises 23.2% by mass of dry air, and when oxygen is consumed at...... parameters; for example, the time to approach steady state depends exponentially on the distance between the soil surface and the subsurface reactive zone. Copyright 2007 by the American Geophysical Union....... at depth in the unsaturated zone, a pressure gradient is created between the reactive zone and the ground surface, causing a substantial advective air flow into the subsurface. To determine the balance between advective and diffusive transport, a one-dimensional multicomponent unsaturated zone gas...

Regulation of replication fork progression through histone supply and demand

DEFF Research Database (Denmark)

Groth, Anja; Corpet, Armelle; Cook, Adam J L

2007-01-01

DNA replication in eukaryotes requires nucleosome disruption ahead of the replication fork and reassembly behind. An unresolved issue concerns how histone dynamics are coordinated with fork progression to maintain chromosomal stability. Here, we characterize a complex in which the human histone c...... progression and histone supply and demand.......1 chaperone function, histone supply, and replicative unwinding of DNA in chromatin. We propose that Asf1, as a histone acceptor and donor, handles parental and new histones at the replication fork via an Asf1-(H3-H4)-MCM2-7 intermediate and thus provides a means to fine-tune replication fork...

High efficiency class-I audio power amplifier using a single adaptive supply

International Nuclear Information System (INIS)

Peng Zhenfei; Yang Shanshand; Feng Yong; Hong Zhiliang; Liu Yang

2012-01-01

A high efficiency class-I linear audio power amplifier (PA) with an adaptive supply is presented. Its efficiency is improved by a dynamic supply to reduce the power transistors' voltage drop. A gain compression technique is adopted to make the amplifier accommodate a single positive supply. Circuit complicity and chip area are reduced because no charge pump is necessary for the negative supply. A common shared mode voltage and a symmetric layout pattern are used to minimize the non-linearity. A peak efficiency of 80% is reached at peak output power. The measured THD+N before and after the supply switching point are 0.01% and 0.05%, respectively. The maximum output power is 410 mW for an 8 Ω speaker load. Unlike switching amplifiers, the class-I amplifier operates as a linear amplifier and hence has a low EMI. The advantage of a high efficiency and low EMI makes the class-I amplifier suitable for portable and RF sensitive applications. (semiconductor integrated circuits)

Reactive Power Support of Electrical Vehicle Charging Station Upgraded with Flywheel Energy Storage System

DEFF Research Database (Denmark)

SUN, BO; Dragicevic, Tomislav; Savaghebi, Mehdi

2015-01-01

Electrical vehicles (EVs) are presenting increasingly potential to replace the conventional fossil fuel based vehicles due to environmental friendly characteristic. Accordingly, Charging Stations (CS), as an intermediate between grid and large numbers of EVs, are supposed to have more critical...... influence on future smart transportation network. This paper explores an off-board charging station upgraded with flywheel energy storage system that could provide a reactive power support to the grid utility. A supervisory control scheme based on distributed bus signaling is proposed to coordinate...... the operation of each component in the system. As a result, the charging station could supply the reactive power support to the utility grid without compromising the charging algorithm and preserve the battery’s lifetime. Finally, the real-time simulation results based on dSPACE1006 verifies the proposed...

Modeling and forecasting the supply of oil and gas: a survey of existing approaches

International Nuclear Information System (INIS)

Walls, M.A.

1992-01-01

This paper surveys the literature on empirical oil and gas supply modeling. The models fall into two broad categories: geologic/engineering and econometric. Two types of geologic/engineering models are surveyed - play analysis, or simulation models and discovery process models. A third category of supply models, 'hybrids', which contain features of both econometric and discovery process models are also discussed. Particular attention is paid to whether or not the models have linkages between a dynamic model of producer optimizing behaviour and the factors governing supply of the resource; whether or not expectations of future prices, costs, and other stochastic variables are incorporated; whether the physical characteristics of non-renewable resources are captured; and how well the models perform. The paper concludes that the best path for future research efforts is a hybrid approach where the econometric component is derived from a stochastic dynamic optimization model of exploration behaviour. 51 refs., 3 figs., 1 tab

Ensuring the Flexibility and Continuity of Supplies in the B2B Market

Directory of Open Access Journals (Sweden)

Grażyna Wieteska

2017-07-01

Full Text Available Aim/purpose - The purpose of this paper is to recognize and compare the best practices that ensure the flexibility and continuity of supplies. Although the flexibility drivers and continuity risk drivers, according to the literature, are actually the same, there is a lack of research articles on this aspect. Design/methodology/approach - A two-phase methodology design, based on the literature review and in-depth interviews, was used, and seven in-depth interviews with the representatives of manufacturing companies that operate in different sectors were conducted. Findings - Supply flexibility and continuity are presented in the literature, mainly as the responses to the business environmental events/changes that have already occurred. Nevertheless, the researched manufacturing companies recognize their use in terms of prevention as well. The researched enterprises use traditional ways of dealing with supply problems (alternative supplier, inventory buffers. They do not really connect ensuring supply continuity with long-term disruptions, but rather understand it as prevention of typical supply delays and quality problems. The respondents regard supplier flexibility not only as a way of responding to the forecasted demand changes but also to unexpected situations. The companies ensure supply continuity and supply flexibility using similar but not exactly the same strategies. For the reactive strategies, sourcing decisions are crucial, whereas for preventive strategies - it is supplier performance management. Research implications/limitations - The small number of conducted interviews is a limitation of performed research, however, some directions for future research can be noted. Apart from other implications described in the paper, it is deduced that sourcing flexibility positively influences supply continuity. Nevertheless, this hypothesis needs quantitative verification.Originality/value/contribution - The paper compares the issue of supply

Coopetitive Supply Chain Relationship Model: Application to the Smartphone Manufacturing Network

Science.gov (United States)

Kwok, Jeremy Jie Ming; Lee, Dong-Yup

2015-01-01

Previous researches for understanding supply chain relationship have mostly focused on its vertical collaboration between buyers and suppliers. However, there have been some instances of volatile and stable collaborative relationships amongst competitors such as Apple-Samsung product manufacturer-component supplier relationship and airline alliances, respectively, which is recognized as coopetition. Even though there have been several qualitative studies and a number of game theory models on coopetition, it is rare to find any attempts on quantitative characterization of such coopetitive dynamic behavior in supply chain relationship. Hence, in this work, we formulated a MINLP model mathematically representing coopetitive relationships in a cost efficient supply chain network. In particular, the coopetition factor was newly introduced to measure the degree of coopetition among supply chain players and determine the optimal level of coopetition to engage in. The utility and practicality of the model were strongly demonstrated using a case study of a hypothetical smartphone supply chain network under different scenarios, thus proposing their strategically viable optimal interactions. Therefore, this exploratory study can herald a new era of global coopetitive business. PMID:26186227

Coopetitive Supply Chain Relationship Model: Application to the Smartphone Manufacturing Network.

Directory of Open Access Journals (Sweden)

Jeremy Jie Ming Kwok

Full Text Available Previous researches for understanding supply chain relationship have mostly focused on its vertical collaboration between buyers and suppliers. However, there have been some instances of volatile and stable collaborative relationships amongst competitors such as Apple-Samsung product manufacturer-component supplier relationship and airline alliances, respectively, which is recognized as coopetition. Even though there have been several qualitative studies and a number of game theory models on coopetition, it is rare to find any attempts on quantitative characterization of such coopetitive dynamic behavior in supply chain relationship. Hence, in this work, we formulated a MINLP model mathematically representing coopetitive relationships in a cost efficient supply chain network. In particular, the coopetition factor was newly introduced to measure the degree of coopetition among supply chain players and determine the optimal level of coopetition to engage in. The utility and practicality of the model were strongly demonstrated using a case study of a hypothetical smartphone supply chain network under different scenarios, thus proposing their strategically viable optimal interactions. Therefore, this exploratory study can herald a new era of global coopetitive business.

Coopetitive Supply Chain Relationship Model: Application to the Smartphone Manufacturing Network.

Science.gov (United States)

Kwok, Jeremy Jie Ming; Lee, Dong-Yup

2015-01-01

Previous researches for understanding supply chain relationship have mostly focused on its vertical collaboration between buyers and suppliers. However, there have been some instances of volatile and stable collaborative relationships amongst competitors such as Apple-Samsung product manufacturer-component supplier relationship and airline alliances, respectively, which is recognized as coopetition. Even though there have been several qualitative studies and a number of game theory models on coopetition, it is rare to find any attempts on quantitative characterization of such coopetitive dynamic behavior in supply chain relationship. Hence, in this work, we formulated a MINLP model mathematically representing coopetitive relationships in a cost efficient supply chain network. In particular, the coopetition factor was newly introduced to measure the degree of coopetition among supply chain players and determine the optimal level of coopetition to engage in. The utility and practicality of the model were strongly demonstrated using a case study of a hypothetical smartphone supply chain network under different scenarios, thus proposing their strategically viable optimal interactions. Therefore, this exploratory study can herald a new era of global coopetitive business.

A Direct Heat Exchanger Unit used for Domestic Hot Water Supply in a Single-family House Supplied by Low Energy District Heating

DEFF Research Database (Denmark)

Brand, Marek; Thorsen, Jan Eric; Svendsen, Svend

2010-01-01