Day-Ahead Coordination of Vehicle-to-Grid Operation and Wind Power in Security Constraints Unit Commitment (SCUC)

OpenAIRE

Mohammad Javad Abdollahi; Majid Moazzami

2015-01-01

In this paper security constraints unit commitment (SCUC) in the presence of wind power resources and electrical vehicles to grid is presented. SCUC operation prepare an optimal time table for generation unit commitment in order to maximize security, minimize operation cost and satisfy the constraints of networks and units in a period of time, as one of the most important research interest in power systems. Today, the relationship between power network and energy storage systems is interested...

Operational Constraints on Hydropeaking and its Effects on the Hydrologic and Thermal Regime of a River in Central Chile

Science.gov (United States)

Olivares, M. A.; Guzman, C.; Rossel, V.; De La Fuente, A.

2013-12-01

Hydropower accounts for about 44% of installed capacity in Chile's Central Interconnected System, which serves most of the Chilean population. Hydropower reservoir projects can affect ecosystems by changing the hydrologic regime and water quality. Given its volumen regulation capacity, low operation costs and fast response to demand fluctuations, reservoir hydropower plants commonly operate on a load-following or hydropeaking scheme. This short-term operational pattern produces alterations in the hydrologic regime downstream the reservoir. In the case of thermally stratified reservoirs, peaking operations can affect the thermal structure of the reservoir, as well as the thermal regime downstream. In this study, we assessed the subdaily hydrologic and thermal alteration donwstream of Rapel reservoir in Central Chile for alternative operational scenarios, including a base case and several scenarios involving minimum instream flow (Qmin) and maximum hourly ramping rates (ΔQmax). Scenarios were simulated for the stratification season of summer 2009-2012 in a grid-wide short-term economic dispatch model which prescribes hourly power production by every power plant on a weekly horizon. Power time series are then translated into time series of turbined flows at each hydropower plants. Indicators of subdaily hydrologic alteration (SDHA) were computed for every scenario. Additionally, turbined flows were used as input data for a three-dimensional hydrodynamic model (CWR-ELCOM) of the reservoir which simulated the vertical temperature profile in the reservoir and the outflow temperature. For the time series of outflow temperatures we computed several indicators of subdaily thermal alteration (SDTA). Operational constraints reduce the values of both SDHA and SDTA indicators with respect to the base case. When constraints are applied separately, the indicators of SDHA decrease as each type of constraint (Qmin or ΔQmax) becomes more stringent. However, ramping rate

Constraints for anomalous dimensions of local light-cone operators in [φ3]6 theory

International Nuclear Information System (INIS)

Mueller, D.

1991-01-01

Using the MS scheme, we derive in [φ 3 ] 6 theory the collinear conformal Ward identity for the Green's functions of local light-cone operators of leading twist. The Ward identity for special collinear conformal transformations and renormalization group invariance give constraints for the off-diagonal part of the anomalous dimension matrix for the general case of β≠0. We compute the anomaly of special conformal tranformation in lowest loop order and obtain from the constraints the off-diagonal part of the anomalous dimension in 2-loop order. (orig.)

Evaluating Direct Manipulation Operations for Constraint-Based Layout

OpenAIRE

Zeidler , Clemens; Lutteroth , Christof; Stuerzlinger , Wolfgang; Weber , Gerald

2013-01-01

Part 11: Interface Layout and Data Entry; International audience; Layout managers are used to control the placement of widgets in graphical user interfaces (GUIs). Constraint-based layout managers are more powerful than other ones. However, they are also more complex and their layouts are prone to problems that usually require direct editing of constraints. Today, designers commonly use GUI builders to specify GUIs. The complexities of traditional approaches to constraint-based layouts pose c...

Operational and geotechnical constraints to coal mining in Alaska's interior

Energy Technology Data Exchange (ETDEWEB)

Corser, P; Usibelli, M

1989-01-01

Surface mining of coal from the Poker Flats mining area to the north of Healy, Alaska began in 1978. Current operations involve a 25 m/sup 3/ walking dragline which strips two coal seams, using an extended bench on the second pass; a fleet of trucks and shovels are used for coal removal and some limited overburden stripping. Geotechnical constraints to mining within the steeply dipping coal deposits are discussed. The area had a number of landslides. During 1984, mining operations close to a landslide caused movement to resume. A mine plan was developed which allowed the coal to be safely removed without inducing additional movement. This involves a dipline mining scheme through the slide area. Future mine plans will acknowledge the hazards of mining through potentially unstable zones. Aerial photographs, field mapping and geological exploration were used. 1 ref., 6 figs.

Effective operators in SUSY, superfield constraints and searches for a UV completion

CERN Document Server

Dudas, E.

2015-01-01

We discuss the role of a class of higher dimensional operators in 4D N=1 supersymmetric effective theories. The Lagrangian in such theories is an expansion in momenta below the scale of "new physics" ($\\Lambda$) and contains the effective operators generated by integrating out the "heavy states" above $\\Lambda$ present in the UV complete theory. We go beyond the "traditional" leading order in this momentum expansion (in $\\partial/\\Lambda$). Keeping manifest supersymmetry and using superfield {\\it constraints} we show that the corresponding higher dimensional (derivative) operators in the sectors of chiral, linear and vector superfields of a Lagrangian can be "unfolded" into second-order operators. The "unfolded" formulation has only polynomial interactions and additional massive superfields, some of which are ghost-like if the effective operators were {\\it quadratic} in fields. Using this formulation, the UV theory emerges naturally and fixes the (otherwise unknown) coefficient and sign of the initial (higher...

Day-Ahead Coordination of Vehicle-to-Grid Operation and Wind Power in Security Constraints Unit Commitment (SCUC

Directory of Open Access Journals (Sweden)

Mohammad Javad Abdollahi

2015-08-01

Full Text Available In this paper security constraints unit commitment (SCUC in the presence of wind power resources and electrical vehicles to grid is presented. SCUC operation prepare an optimal time table for generation unit commitment in order to maximize security, minimize operation cost and satisfy the constraints of networks and units in a period of time, as one of the most important research interest in power systems. Today, the relationship between power network and energy storage systems is interested for many researchers and network operators. Using Electrical Vehicles (PEVs and wind power for energy production is one of the newest proposed methods for replacing fossil fuels.One of the effective strategies for analyzing of the effects of Vehicle 2 Grid (V2G and wind power in optimal operation of generation is running of SCUC for power systems that are equipped with V2G and wind power resources. In this paper, game theory method is employed for deterministic solution of day-ahead unit commitment with considering security constraints in the simultaneous presence of V2G and wind power units. This problem for two scenarios of grid-controlled mode and consumer-controlled mode in three different days with light, medium and heavy load profiles is analyzed. Simulation results show the effectiveness of the presence of V2G and wind power for decreasing of generation cost and improving operation indices of power systems.

Development of a decision support tool for seasonal water supply management incorporating system uncertainties and operational constraints

Science.gov (United States)

Wang, H.; Asefa, T.

2017-12-01

A real-time decision support tool (DST) for water supply system would consider system uncertainties, e.g., uncertain streamflow and demand, as well as operational constraints and infrastructure outage (e.g., pump station shutdown, an offline reservoir due to maintenance). Such DST is often used by water managers for resource allocation and delivery for customers. Although most seasonal DST used by water managers recognize those system uncertainties and operational constraints, most use only historical information or assume deterministic outlook of water supply systems. This study presents a seasonal DST that incorporates rainfall/streamflow uncertainties, seasonal demand outlook and system operational constraints. Large scale climate-information is captured through a rainfall simulator driven by a Bayesian non-homogeneous Markov Chain Monte Carlo model that allows non-stationary transition probabilities contingent on Nino 3.4 index. An ad-hoc seasonal demand forecasting model considers weather conditions explicitly and socio-economic factors implicitly. Latin Hypercube sampling is employed to effectively sample probability density functions of flow and demand. Seasonal system operation is modelled as a mixed-integer optimization problem that aims at minimizing operational costs. It embeds the flexibility of modifying operational rules at different components, e.g., surface water treatment plants, desalination facilities, and groundwater pumping stations. The proposed framework is illustrated at a wholesale water supplier in Southeastern United States, Tampa Bay Water. The use of the tool is demonstrated in proving operational guidance in a typical drawdown and refill cycle of a regional reservoir. The DST provided: 1) probabilistic outlook of reservoir storage and chance of a successful refill by the end of rainy season; 2) operational expectations for large infrastructures (e.g., high service pumps and booster stations) throughout the season. Other potential use

Analytical design of an industrial two-term controller for optimal regulatory control of open-loop unstable processes under operational constraints.

Science.gov (United States)

Tchamna, Rodrigue; Lee, Moonyong

2018-01-01

This paper proposes a novel optimization-based approach for the design of an industrial two-term proportional-integral (PI) controller for the optimal regulatory control of unstable processes subjected to three common operational constraints related to the process variable, manipulated variable and its rate of change. To derive analytical design relations, the constrained optimal control problem in the time domain was transformed into an unconstrained optimization problem in a new parameter space via an effective parameterization. The resulting optimal PI controller has been verified to yield optimal performance and stability of an open-loop unstable first-order process under operational constraints. The proposed analytical design method explicitly takes into account the operational constraints in the controller design stage and also provides useful insights into the optimal controller design. Practical procedures for designing optimal PI parameters and a feasible constraint set exclusive of complex optimization steps are also proposed. The proposed controller was compared with several other PI controllers to illustrate its performance. The robustness of the proposed controller against plant-model mismatch has also been investigated. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Model-based minimization algorithm of a supercritical helium loop consumption subject to operational constraints

Science.gov (United States)

Bonne, F.; Bonnay, P.; Girard, A.; Hoa, C.; Lacroix, B.; Le Coz, Q.; Nicollet, S.; Poncet, J.-M.; Zani, L.

2017-12-01

Supercritical helium loops at 4.2 K are the baseline cooling strategy of tokamaks superconducting magnets (JT-60SA, ITER, DEMO, etc.). This loops work with cryogenic circulators that force a supercritical helium flow through the superconducting magnets in order that the temperature stay below the working range all along their length. This paper shows that a supercritical helium loop associated with a saturated liquid helium bath can satisfy temperature constraints in different ways (playing on bath temperature and on the supercritical flow), but that only one is optimal from an energy point of view (every Watt consumed at 4.2 K consumes at least 220 W of electrical power). To find the optimal operational conditions, an algorithm capable of minimizing an objective function (energy consumption at 5 bar, 5 K) subject to constraints has been written. This algorithm works with a supercritical loop model realized with the Simcryogenics [2] library. This article describes the model used and the results of constrained optimization. It will be possible to see that the changes in operating point on the temperature of the magnet (e.g. in case of a change in the plasma configuration) involves large changes on the cryodistribution optimal operating point. Recommendations will be made to ensure that the energetic consumption is kept as low as possible despite the changing operating point. This work is partially supported by EUROfusion Consortium through the Euratom Research and Training Program 20142018 under Grant 633053.

Constraint Embedding for Multibody System Dynamics

Science.gov (United States)

Jain, Abhinandan

2009-01-01

This paper describes a constraint embedding approach for the handling of local closure constraints in multibody system dynamics. The approach uses spatial operator techniques to eliminate local-loop constraints from the system and effectively convert the system into tree-topology systems. This approach allows the direct derivation of recursive O(N) techniques for solving the system dynamics and avoiding the expensive steps that would otherwise be required for handling the closedchain dynamics. The approach is very effective for systems where the constraints are confined to small-subgraphs within the system topology. The paper provides background on the spatial operator O(N) algorithms, the extensions for handling embedded constraints, and concludes with some examples of such constraints.

Analytical design of proportional-integral controllers for the optimal control of first-order processes with operational constraints

Energy Technology Data Exchange (ETDEWEB)

Thu, Hien Cao Thi; Lee, Moonyong [Yeungnam University, Gyeongsan (Korea, Republic of)

2013-12-15

A novel analytical design method of industrial proportional-integral (PI) controllers was developed for the optimal control of first-order processes with operational constraints. The control objective was to minimize a weighted sum of the controlled variable error and the rate of change in the manipulated variable under the maximum allowable limits in the controlled variable, manipulated variable and the rate of change in the manipulated variable. The constrained optimal servo control problem was converted to an unconstrained optimization to obtain an analytical tuning formula. A practical shortcut procedure for obtaining optimal PI parameters was provided based on graphical analysis of global optimality. The proposed PI controller was found to guarantee global optimum and deal explicitly with the three important operational constraints.

Comparison of Multiobjective Evolutionary Algorithms for Operations Scheduling under Machine Availability Constraints

Directory of Open Access Journals (Sweden)

M. Frutos

2013-01-01

Full Text Available Many of the problems that arise in production systems can be handled with multiobjective techniques. One of those problems is that of scheduling operations subject to constraints on the availability of machines and buffer capacity. In this paper we analyze different Evolutionary multiobjective Algorithms (MOEAs for this kind of problems. We consider an experimental framework in which we schedule production operations for four real world Job-Shop contexts using three algorithms, NSGAII, SPEA2, and IBEA. Using two performance indexes, Hypervolume and R2, we found that SPEA2 and IBEA are the most efficient for the tasks at hand. On the other hand IBEA seems to be a better choice of tool since it yields more solutions in the approximate Pareto frontier.

XY vs X Mixer in Quantum Alternating Operator Ansatz for Optimization Problems with Constraints

Science.gov (United States)

Wang, Zhihui; Rubin, Nicholas; Rieffel, Eleanor G.

2018-01-01

Quantum Approximate Optimization Algorithm, further generalized as Quantum Alternating Operator Ansatz (QAOA), is a family of algorithms for combinatorial optimization problems. It is a leading candidate to run on emerging universal quantum computers to gain insight into quantum heuristics. In constrained optimization, penalties are often introduced so that the ground state of the cost Hamiltonian encodes the solution (a standard practice in quantum annealing). An alternative is to choose a mixing Hamiltonian such that the constraint corresponds to a constant of motion and the quantum evolution stays in the feasible subspace. Better performance of the algorithm is speculated due to a much smaller search space. We consider problems with a constant Hamming weight as the constraint. We also compare different methods of generating the generalized W-state, which serves as a natural initial state for the Hamming-weight constraint. Using graph-coloring as an example, we compare the performance of using XY model as a mixer that preserves the Hamming weight with the performance of adding a penalty term in the cost Hamiltonian.

Quantum information density scaling and qubit operation time constraints of CMOS silicon-based quantum computer architectures

Science.gov (United States)

Rotta, Davide; Sebastiano, Fabio; Charbon, Edoardo; Prati, Enrico

2017-06-01

Even the quantum simulation of an apparently simple molecule such as Fe2S2 requires a considerable number of qubits of the order of 106, while more complex molecules such as alanine (C3H7NO2) require about a hundred times more. In order to assess such a multimillion scale of identical qubits and control lines, the silicon platform seems to be one of the most indicated routes as it naturally provides, together with qubit functionalities, the capability of nanometric, serial, and industrial-quality fabrication. The scaling trend of microelectronic devices predicting that computing power would double every 2 years, known as Moore's law, according to the new slope set after the 32-nm node of 2009, suggests that the technology roadmap will achieve the 3-nm manufacturability limit proposed by Kelly around 2020. Today, circuital quantum information processing architectures are predicted to take advantage from the scalability ensured by silicon technology. However, the maximum amount of quantum information per unit surface that can be stored in silicon-based qubits and the consequent space constraints on qubit operations have never been addressed so far. This represents one of the key parameters toward the implementation of quantum error correction for fault-tolerant quantum information processing and its dependence on the features of the technology node. The maximum quantum information per unit surface virtually storable and controllable in the compact exchange-only silicon double quantum dot qubit architecture is expressed as a function of the complementary metal-oxide-semiconductor technology node, so the size scale optimizing both physical qubit operation time and quantum error correction requirements is assessed by reviewing the physical and technological constraints. According to the requirements imposed by the quantum error correction method and the constraints given by the typical strength of the exchange coupling, we determine the workable operation frequency

The influence of operational constraints in the production strategy definition; Influencia de restricoes operacionais na definicao da estrategia de producao

Energy Technology Data Exchange (ETDEWEB)

Magalhaes, Tasso C.B. de; Schiozer, Denis J. [Universidade Estadual de Campinas, SP (Brazil)

2004-07-01

Production strategies definition, applied to petroleum fields, must consider physical, operational and economic constraints. It is common to consider only the reservoir conditions on the optimization processes, simplifying, many times, the process by not taking into account the operational constraints due to production facilities. There are two main reasons: considering the operational constraints makes the process much complex and it is assumed that this simplification can affect the economic indicators but dos not affect significantly the optimization process (number e location of wells, for example). The capacity of a production unit can be limited by many constrains such as: maximum liquid rate, capacity of water and gas treatment, gas compression, water or gas injection, number of wells, etc. In this work, we show that these limitations have a direct influence in the oil production and consequently in the economic indicators and they can cause significant impact at production strategy definition, influencing the number of production and injection wells, their locations and their operational conditions. We presented an example of an offshore field with a limitation on the liquid rate. Production strategies were selected with and without constraints in order to observe the differences in the technical and economic indicators, such as NPV (Net Present Value), production and injection of fluids and the number and location of the production and injection wells. It was possible to observe yet that the amount and location of the wells were significantly affected by the restriction. (author)

Gauge systems and functions, hermitian operators and clocks as conjugate functions for the constraints

International Nuclear Information System (INIS)

Cuesta, Vladimir; Vergara, Jose David; Montesinos, Merced

2011-01-01

We work with gauge systems and using gauge invariant functions we study its quantum counterpart and we find if all these operators are self adjoint or not. Our study is divided in two cases, when we choose clock or clocks that its Poisson brackets with the set of constraints is one or it is different to one. We show some transition amplitudes.

SELF: expert system for supporting verification of network operating constraints in power transmission planning

Energy Technology Data Exchange (ETDEWEB)

Cicoria, R; Migliardi, P [Ente Nazionale per l` Energia Elettrica, Milan (Italy); Pogliano, P [Centro Informazioni Studi Esperienze (CISE), Milan (Italy)

1995-06-01

Performing planned studies into very large HV transmission systems is a very complex task which requires the use of simulation models and the application of the heuristic acquired by expert palnners during previous studies. The ENEL Electric Research Center and the CISE Artificial Intelligence Section have developed a knowledge-based system, named SELF, which is aimed at supporting the transmission system palnner. SELF is capable of assisting the engineer both in finding the convergence of the load flow calculation and determining solutions that respect active power, voltage and VAR operating constraints. This paper describes the overall architecture of the system and shows its integration in a larger planning environment called SPIRA, currently utilized at ENEL. More details are given on the least completed modules, the redispatching and network reinforcement subsystems which deal with active power constraint verification.

Determination of fault operation dynamical constraints for the design of wind turbine DFIG drives

CERN Document Server

Aguglia, Davide; Wamkeue, René; Cros, Jérôme

2010-01-01

This paper presents an efficient design tool for the estimation of the transient electromagnetic peak torque and transient rotor over-voltages of wind turbines (WT) doubly-fed induction generators (DFIG) during severe fault conditions on the grid side. This versatile and robust tool is well adapted to the implementation in a DFIG drives CAD environment using iterative optimization procedures. In such an application, it is used to compute the dynamical constraints function during the integrated design process of the whole drive including the generator, the gearbox and the power converters. Results show that it is necessary to take into account the dynamical constraints under fault operation, during the early steps of the system design process. Another application of the tool is also illustrated in the paper: the design of the protection system (i.e. the crowbar resistance) for a given generator, a given gearbox and a given power converter.

Causality constraints in conformal field theory

Energy Technology Data Exchange (ETDEWEB)

Hartman, Thomas; Jain, Sachin; Kundu, Sandipan [Department of Physics, Cornell University,Ithaca, New York (United States)

2016-05-17

Causality places nontrivial constraints on QFT in Lorentzian signature, for example fixing the signs of certain terms in the low energy Lagrangian. In d dimensional conformal field theory, we show how such constraints are encoded in crossing symmetry of Euclidean correlators, and derive analogous constraints directly from the conformal bootstrap (analytically). The bootstrap setup is a Lorentzian four-point function corresponding to propagation through a shockwave. Crossing symmetry fixes the signs of certain log terms that appear in the conformal block expansion, which constrains the interactions of low-lying operators. As an application, we use the bootstrap to rederive the well known sign constraint on the (∂ϕ){sup 4} coupling in effective field theory, from a dual CFT. We also find constraints on theories with higher spin conserved currents. Our analysis is restricted to scalar correlators, but we argue that similar methods should also impose nontrivial constraints on the interactions of spinning operators.

Learning and Parallelization Boost Constraint Search

Science.gov (United States)

Yun, Xi

2013-01-01

Constraint satisfaction problems are a powerful way to abstract and represent academic and real-world problems from both artificial intelligence and operations research. A constraint satisfaction problem is typically addressed by a sequential constraint solver running on a single processor. Rather than construct a new, parallel solver, this work…

Reduction of Constraints: Applicability of the Homogeneity Constraint for Macrobatch 3

International Nuclear Information System (INIS)

Peeler, D.K.

2001-01-01

The Product Composition Control System (PCCS) is used to determine the acceptability of each batch of Defense Waste Processing Facility (DWPF) melter feed in the Slurry Mix Evaporator (SME). This control system imposes several constraints on the composition of the contents of the SME to define acceptability. These constraints relate process or product properties to composition via prediction models. A SME batch is deemed acceptable if its sample composition measurements lead to acceptable property predictions after accounting for modeling, measurement and analytic uncertainties. The baseline document guiding the use of these data and models is ''SME Acceptability Determination for DWPF Process Control (U)'' by Brown and Postles [1996]. A minimum of three PCCS constraints support the prediction of the glass durability from a given SME batch. The Savannah River Technology Center (SRTC) is reviewing all of the PCCS constraints associated with durability. The purpose of this review is to revisit these constraints in light of the additional knowledge gained since the beginning of radioactive operations at DWPF and to identify any supplemental studies needed to amplify this knowledge so that redundant or overly conservative constraints can be eliminated or replaced by more appropriate constraints

A study on relationship between operating cash flows and performance evaluation criteria based on the theory of constraints (TOC versus traditional method

Directory of Open Access Journals (Sweden)

Mohammad Sadegh Arabi Ashtiani

2013-08-01

Full Text Available This study presents an empirical investigation to measure the relationship between traditional accounting performance measurement as well as theory of constraint-based figures with operating cash flow. Traditional accounting measurement includes net profit and return of investment and theory of constraint method includes net profit and return of investment based on theory of constraints. The study selects 69 firms list on Tehran Stock Exchange over the period 2000-2010. Using panel data and fixed effect, the study performs regression analysis and the results confirm that there was a positive relationship between net profit measured by theory of constraints and cash flow and it can be effectively used for performance measurement.

Machine tongues. X. Constraint languages

Energy Technology Data Exchange (ETDEWEB)

Levitt, D.

Constraint languages and programming environments will help the designer produce a lucid description of a problem domain, and then of particular situations and problems in it. Early versions of these languages were given descriptions of real world domain constraints, like the operation of electrical and mechanical parts. More recently, the author has automated a vocabulary for describing musical jazz phrases, using constraint language as a jazz improviser. General constraint languages will handle all of these domains. Once the model is in place, the system will connect built-in code fragments and algorithms to answer questions about situations; that is, to help solve problems. Bugs will surface not in code, but in designs themselves. 15 references.

Hamiltonian constraint in polymer parametrized field theory

International Nuclear Information System (INIS)

Laddha, Alok; Varadarajan, Madhavan

2011-01-01

Recently, a generally covariant reformulation of two-dimensional flat spacetime free scalar field theory known as parametrized field theory was quantized using loop quantum gravity (LQG) type ''polymer'' representations. Physical states were constructed, without intermediate regularization structures, by averaging over the group of gauge transformations generated by the constraints, the constraint algebra being a Lie algebra. We consider classically equivalent combinations of these constraints corresponding to a diffeomorphism and a Hamiltonian constraint, which, as in gravity, define a Dirac algebra. Our treatment of the quantum constraints parallels that of LQG and obtains the following results, expected to be of use in the construction of the quantum dynamics of LQG: (i) the (triangulated) Hamiltonian constraint acts only on vertices, its construction involves some of the same ambiguities as in LQG and its action on diffeomorphism invariant states admits a continuum limit, (ii) if the regulating holonomies are in representations tailored to the edge labels of the state, all previously obtained physical states lie in the kernel of the Hamiltonian constraint, (iii) the commutator of two (density weight 1) Hamiltonian constraints as well as the operator correspondent of their classical Poisson bracket converge to zero in the continuum limit defined by diffeomorphism invariant states, and vanish on the Lewandowski-Marolf habitat, (iv) the rescaled density 2 Hamiltonian constraints and their commutator are ill-defined on the Lewandowski-Marolf habitat despite the well-definedness of the operator correspondent of their classical Poisson bracket there, (v) there is a new habitat which supports a nontrivial representation of the Poisson-Lie algebra of density 2 constraints.

Overview of the use of dose constraints in occupational exposures

International Nuclear Information System (INIS)

Bonny, A.

2013-04-01

An overview of the use of dose constraints in occupational exposures has been carried out in this project. This was done by reviewing and analyzing some of the operational issues/challenges associated with their implementation and providing suggestions regarding operational objectives and uses of dose constraints.The role of dose constraints in the process of optimisation of radiation protection was described, and explanations provided where necessary in order to avoid the possible situations where dose constraints are misinterpreted or used as a stringent limit. Finally, the identification of potential issues that need to be considered in the implementation and setting of dose constraints for the purposes of occupational radiation protection were discussed. (author)

Automated Air Traffic Control Operations with Weather and Time-Constraints: A First Look at (Simulated) Far-Term Control Room Operations

Science.gov (United States)

Prevot, Thomas; Homola, Jeffrey R.; Martin, Lynne H.; Mercer, Joey S.; Cabrall, Christopher C.

2011-01-01

In this paper we discuss results from a recent high fidelity simulation of air traffic control operations with automated separation assurance in the presence of weather and time-constraints. We report findings from a human-in-the-loop study conducted in the Airspace Operations Laboratory (AOL) at the NASA Ames Research Center. During four afternoons in early 2010, fifteen active and recently retired air traffic controllers and supervisors controlled high levels of traffic in a highly automated environment during three-hour long scenarios, For each scenario, twelve air traffic controllers operated eight sector positions in two air traffic control areas and were supervised by three front line managers, Controllers worked one-hour shifts, were relieved by other controllers, took a 3D-minute break, and worked another one-hour shift. On average, twice today's traffic density was simulated with more than 2200 aircraft per traffic scenario. The scenarios were designed to create peaks and valleys in traffic density, growing and decaying convective weather areas, and expose controllers to heavy and light metering conditions. This design enabled an initial look at a broad spectrum of workload, challenge, boredom, and fatigue in an otherwise uncharted territory of future operations. In this paper we report human/system integration aspects, safety and efficiency results as well as airspace throughput, workload, and operational acceptability. We conclude that, with further refinements. air traffic control operations with ground-based automated separation assurance can be an effective and acceptable means to routinely provide very high traffic throughput in the en route airspace.

Constraint Embedding Technique for Multibody System Dynamics

Science.gov (United States)

Woo, Simon S.; Cheng, Michael K.

2011-01-01

Multibody dynamics play a critical role in simulation testbeds for space missions. There has been a considerable interest in the development of efficient computational algorithms for solving the dynamics of multibody systems. Mass matrix factorization and inversion techniques and the O(N) class of forward dynamics algorithms developed using a spatial operator algebra stand out as important breakthrough on this front. Techniques such as these provide the efficient algorithms and methods for the application and implementation of such multibody dynamics models. However, these methods are limited only to tree-topology multibody systems. Closed-chain topology systems require different techniques that are not as efficient or as broad as those for tree-topology systems. The closed-chain forward dynamics approach consists of treating the closed-chain topology as a tree-topology system subject to additional closure constraints. The resulting forward dynamics solution consists of: (a) ignoring the closure constraints and using the O(N) algorithm to solve for the free unconstrained accelerations for the system; (b) using the tree-topology solution to compute a correction force to enforce the closure constraints; and (c) correcting the unconstrained accelerations with correction accelerations resulting from the correction forces. This constraint-embedding technique shows how to use direct embedding to eliminate local closure-loops in the system and effectively convert the system back to a tree-topology system. At this point, standard tree-topology techniques can be brought to bear on the problem. The approach uses a spatial operator algebra approach to formulating the equations of motion. The operators are block-partitioned around the local body subgroups to convert them into aggregate bodies. Mass matrix operator factorization and inversion techniques are applied to the reformulated tree-topology system. Thus in essence, the new technique allows conversion of a system with

Linear determining equations for differential constraints

International Nuclear Information System (INIS)

Kaptsov, O V

1998-01-01

A construction of differential constraints compatible with partial differential equations is considered. Certain linear determining equations with parameters are used to find such differential constraints. They generalize the classical determining equations used in the search for admissible Lie operators. As applications of this approach equations of an ideal incompressible fluid and non-linear heat equations are discussed

Causality Constraints in Conformal Field Theory

CERN Multimedia

CERN. Geneva

2015-01-01

Causality places nontrivial constraints on QFT in Lorentzian signature, for example fixing the signs of certain terms in the low energy Lagrangian. In d-dimensional conformal field theory, we show how such constraints are encoded in crossing symmetry of Euclidean correlators, and derive analogous constraints directly from the conformal bootstrap (analytically). The bootstrap setup is a Lorentzian four-point function corresponding to propagation through a shockwave. Crossing symmetry fixes the signs of certain log terms that appear in the conformal block expansion, which constrains the interactions of low-lying operators. As an application, we use the bootstrap to rederive the well known sign constraint on the (∂φ)4 coupling in effective field theory, from a dual CFT. We also find constraints on theories with higher spin conserved currents. Our analysis is restricted to scalar correlators, but we argue that similar methods should also impose nontrivial constraints on the interactions of spinni...

Technology transfer to Africa: constraints for CDM operations

International Nuclear Information System (INIS)

Karani, Patrick

2002-01-01

It is practically difficult to design, implement and manage Clean Development Mechanism (CDM) projects in Africa without a provision for capacity building that will enable the application of modern technologies and techniques. Existing institutions need strengthening, human capacity needs to be developed and new markets need to be promoted. The author outlines institutional and market constraints in relation to technology transfer (e.g renewable energy technologies) and development in Africa. (Author)

Constraint-based scheduling

Science.gov (United States)

Zweben, Monte

1993-01-01

The GERRY scheduling system developed by NASA Ames with assistance from the Lockheed Space Operations Company, and the Lockheed Artificial Intelligence Center, uses a method called constraint-based iterative repair. Using this technique, one encodes both hard rules and preference criteria into data structures called constraints. GERRY repeatedly attempts to improve schedules by seeking repairs for violated constraints. The system provides a general scheduling framework which is being tested on two NASA applications. The larger of the two is the Space Shuttle Ground Processing problem which entails the scheduling of all the inspection, repair, and maintenance tasks required to prepare the orbiter for flight. The other application involves power allocation for the NASA Ames wind tunnels. Here the system will be used to schedule wind tunnel tests with the goal of minimizing power costs. In this paper, we describe the GERRY system and its application to the Space Shuttle problem. We also speculate as to how the system would be used for manufacturing, transportation, and military problems.

Airborne Management of Traffic Conflicts in Descent With Arrival Constraints

Science.gov (United States)

Doble, Nathan A.; Barhydt, Richard; Krishnamurthy, Karthik

2005-01-01

NASA is studying far-term air traffic management concepts that may increase operational efficiency through a redistribution of decisionmaking authority among airborne and ground-based elements of the air transportation system. One component of this research, En Route Free Maneuvering, allows trained pilots of equipped autonomous aircraft to assume responsibility for traffic separation. Ground-based air traffic controllers would continue to separate traffic unequipped for autonomous operations and would issue flow management constraints to all aircraft. To evaluate En Route Free Maneuvering operations, a human-in-the-loop experiment was jointly conducted by the NASA Ames and Langley Research Centers. In this experiment, test subject pilots used desktop flight simulators to resolve conflicts in cruise and descent, and to adhere to air traffic flow constraints issued by test subject controllers. Simulators at NASA Langley were equipped with a prototype Autonomous Operations Planner (AOP) flight deck toolset to assist pilots with conflict management and constraint compliance tasks. Results from the experiment are presented, focusing specifically on operations during the initial descent into the terminal area. Airborne conflict resolution performance in descent, conformance to traffic flow management constraints, and the effects of conflicting traffic on constraint conformance are all presented. Subjective data from subject pilots are also presented, showing perceived levels of workload, safety, and acceptability of autonomous arrival operations. Finally, potential AOP functionality enhancements are discussed along with suggestions to improve arrival procedures.

Constraints from proton decay in the flipped SU(5)xU(1) superstring model

Energy Technology Data Exchange (ETDEWEB)

Leontaris, G.K.; Tamvakis, K. (Ioannina Univ. (Greece). Theoretical Physics Div.)

1991-05-16

We discuss the constraints the emerge from the existence of dimension-5 baryon-violating operators in the flipped SU(5) x U(1) superstring model. These are constraints on matter field assignments and on singlet VEV values. Although baryon-violating dimension-5 operators that appear as quintic non-renormalizable terms vanish as has been proven before and as we verify here, effective dimension-5 operators resulting from Higgs exchange put non-trivial but feasible constraints on the model. Constraints are also extracted from the presence of higher order non-renormalizable terms that generate such operators which do not a priori vanish. (orig.).

Improving SALT productivity by using the theory of constraints

Science.gov (United States)

Coetzee, Johannes C.; Väisänen, Petri; O'Donoghue, Darragh E.; Kotze, Paul; Romero Colmenero, Encarni; Miszalski, Brent; Crawford, Steven M.; Kniazev, Alexei; Depagne, Éric; Rabe, Paul; Hettlage, Christian

2016-07-01

SALT, the Southern African Large Telescope, is a very cost effective 10 m class telescope. The operations cost per refereed science paper is currently approximately $70,000. To achieve this competitive advantage, specific design tradeoffs had to be made leading to technical constraints. On the other hand, the telescope has many advantages, such as being able to rapidly switch between different instruments and observing modes during the night. We provide details of the technical and operational constraints and how they were dealt with, by applying the theory of constraints, to substantially improve the observation throughput during the last semester.

An adaptive ES with a ranking based constraint handling strategy

Directory of Open Access Journals (Sweden)

Kusakci Ali Osman

2014-01-01

Full Text Available To solve a constrained optimization problem, equality constraints can be used to eliminate a problem variable. If it is not feasible, the relations imposed implicitly by the constraints can still be exploited. Most conventional constraint handling methods in Evolutionary Algorithms (EAs do not consider the correlations between problem variables imposed by the constraints. This paper relies on the idea that a proper search operator, which captures mentioned implicit correlations, can improve performance of evolutionary constrained optimization algorithms. To realize this, an Evolution Strategy (ES along with a simplified Covariance Matrix Adaptation (CMA based mutation operator is used with a ranking based constraint-handling method. The proposed algorithm is tested on 13 benchmark problems as well as on a real life design problem. The outperformance of the algorithm is significant when compared with conventional ES-based methods.

Constraint satisfaction problems CSP formalisms and techniques

CERN Document Server

Ghedira, Khaled

2013-01-01

A Constraint Satisfaction Problem (CSP) consists of a set of variables, a domain of values for each variable and a set of constraints. The objective is to assign a value for each variable such that all constraints are satisfied. CSPs continue to receive increased attention because of both their high complexity and their omnipresence in academic, industrial and even real-life problems. This is why they are the subject of intense research in both artificial intelligence and operations research. This book introduces the classic CSP and details several extensions/improvements of both formalisms a

Ethical Issues and Legal Constraints to the Freedom of Information Act

African Journals Online (AJOL)

Unfortunately, there are legal constraints that can hinder the smooth operation of the act. Such constraints need to be dismantled immediately. Besides, there is a great need to address various ethical issue that may equally arise among media practitioners in the course of operating within the limits of the law, posing great ...

A short-term operating room surgery scheduling problem integrating multiple nurses roster constraints.

Science.gov (United States)

Xiang, Wei; Yin, Jiao; Lim, Gino

2015-02-01

Operating room (OR) surgery scheduling determines the individual surgery's operation start time and assigns the required resources to each surgery over a schedule period, considering several constraints related to a complete surgery flow and the multiple resources involved. This task plays a decisive role in providing timely treatments for the patients while balancing hospital resource utilization. The originality of the present study is to integrate the surgery scheduling problem with real-life nurse roster constraints such as their role, specialty, qualification and availability. This article proposes a mathematical model and an ant colony optimization (ACO) approach to efficiently solve such surgery scheduling problems. A modified ACO algorithm with a two-level ant graph model is developed to solve such combinatorial optimization problems because of its computational complexity. The outer ant graph represents surgeries, while the inner graph is a dynamic resource graph. Three types of pheromones, i.e. sequence-related, surgery-related, and resource-related pheromone, fitting for a two-level model are defined. The iteration-best and feasible update strategy and local pheromone update rules are adopted to emphasize the information related to the good solution in makespan, and the balanced utilization of resources as well. The performance of the proposed ACO algorithm is then evaluated using the test cases from (1) the published literature data with complete nurse roster constraints, and 2) the real data collected from a hospital in China. The scheduling results using the proposed ACO approach are compared with the test case from both the literature and the real life hospital scheduling. Comparison results with the literature shows that the proposed ACO approach has (1) an 1.5-h reduction in end time; (2) a reduction in variation of resources' working time, i.e. 25% for ORs, 50% for nurses in shift 1 and 86% for nurses in shift 2; (3) an 0.25h reduction in

A constraint-based bottom-up counterpart to definite clause grammars

DEFF Research Database (Denmark)

Christiansen, Henning

2004-01-01

A new grammar formalism, CHR Grammars (CHRG), is proposed that provides a constraint-solving approach to language analysis, built on top of the programming language of Constraint Handling Rules in the same way as Definite Clause Grammars (DCG) on Prolog. CHRG works bottom-up and adds the following......, integrity constraints, operators a la assumption grammars, and to incorporate other constraint solvers. (iv)~Context-sensitive rules that apply for disambiguation, coordination in natural language and tagger-like rules....

Distribution system constraints and their impact on distributed generation: final report

Energy Technology Data Exchange (ETDEWEB)

Thornycroft, J.; Caisley, A.; Russell, T.; Willis, S.; Youssef, R.; Bawden, R.; Holden, G.; Williams, J.

2004-05-01

This report examines constraints due to the connection of distributed generators to the distribution network focusing on small generators with the aim of developing technical and economic models to examine the relationship between the initial investment and the ensuing cost of the constraints under different scenarios. Constraints are defined as limitations to operation of connected generators, and the types of constraints, and the allocation of reinforcement and constraint costs are considered. Details are given of the modeling of sections of urban, rural and semi-rural network at Faversham, and the current constraints on this network are described.

Domain general constraints on statistical learning.

Science.gov (United States)

Thiessen, Erik D

2011-01-01

All theories of language development suggest that learning is constrained. However, theories differ on whether these constraints arise from language-specific processes or have domain-general origins such as the characteristics of human perception and information processing. The current experiments explored constraints on statistical learning of patterns, such as the phonotactic patterns of an infants' native language. Infants in these experiments were presented with a visual analog of a phonotactic learning task used by J. R. Saffran and E. D. Thiessen (2003). Saffran and Thiessen found that infants' phonotactic learning was constrained such that some patterns were learned more easily than other patterns. The current results indicate that infants' learning of visual patterns shows the same constraints as infants' learning of phonotactic patterns. This is consistent with theories suggesting that constraints arise from domain-general sources and, as such, should operate over many kinds of stimuli in addition to linguistic stimuli. © 2011 The Author. Child Development © 2011 Society for Research in Child Development, Inc.

Wave functions constructed from an invariant sum over histories satisfy constraints

International Nuclear Information System (INIS)

Halliwell, J.J.; Hartle, J.B.

1991-01-01

Invariance of classical equations of motion under a group parametrized by functions of time implies constraints between canonical coordinates and momenta. In the Dirac formulation of quantum mechanics, invariance is normally imposed by demanding that physical wave functions are annihilated by the operator versions of these constraints. In the sum-over-histories quantum mechanics, however, wave functions are specified, directly, by appropriate functional integrals. It therefore becomes an interesting question whether the wave functions so specified obey the operator constraints of the Dirac theory. In this paper, we show for a wide class of theories, including gauge theories, general relativity, and first-quantized string theories, that wave functions constructed from a sum over histories are, in fact, annihilated by the constraints provided that the sum over histories is constructed in a manner which respects the invariance generated by the constraints. By this we mean a sum over histories defined with an invariant action, invariant measure, and an invariant class of paths summed over

Constraint Programming versus Mathematical Programming

DEFF Research Database (Denmark)

Hansen, Jesper

2003-01-01

Constraint Logic Programming (CLP) is a relatively new technique from the 80's with origins in Computer Science and Artificial Intelligence. Lately, much research have been focused on ways of using CLP within the paradigm of Operations Research (OR) and vice versa. The purpose of this paper...

Constraint-Checking Editor for Procedure Tracking (ConCEPT), Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Constructing, maintaining, and adapting operational procedures for manned space operations is a complex task, requiring the procedure author to satisfy constraints...

Constraints, Trade-offs and the Currency of Fitness.

Science.gov (United States)

Acerenza, Luis

2016-03-01

Understanding evolutionary trajectories remains a difficult task. This is because natural evolutionary processes are simultaneously affected by various types of constraints acting at the different levels of biological organization. Of particular importance are constraints where correlated changes occur in opposite directions, called trade-offs. Here we review and classify the main evolutionary constraints and trade-offs, operating at all levels of trait hierarchy. Special attention is given to life history trade-offs and the conflict between the survival and reproduction components of fitness. Cellular mechanisms underlying fitness trade-offs are described. At the metabolic level, a linear trade-off between growth and flux variability was found, employing bacterial genome-scale metabolic reconstructions. Its analysis indicates that flux variability can be considered as the currency of fitness. This currency is used for fitness transfer between fitness components during adaptations. Finally, a discussion is made regarding the constraints which limit the increase in the amount of fitness currency during evolution, suggesting that occupancy constraints are probably the main restrictions.

Lorentz violation. Motivation and new constraints

Energy Technology Data Exchange (ETDEWEB)

Liberati, S. [Scuola Internazionale Superiore di Studi Avanzati SISSA, Trieste (Italy); Istituto Nazionale di Fisica Nucleare INFN, Sezione di Trieste (Italy); Maccione, L. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2009-09-15

We review the main theoretical motivations and observational constraints on Planck scale sup-pressed violations of Lorentz invariance. After introducing the problems related to the phenomenological study of quantum gravitational effects, we discuss the main theoretical frameworks within which possible departures from Lorentz invariance can be described. In particular, we focus on the framework of Effective Field Theory, describing several possible ways of including Lorentz violation therein and discussing their theoretical viability. We review the main low energy effects that are expected in this framework. We discuss the current observational constraints on such a framework, focusing on those achievable through high-energy astrophysics observations. In this context we present a summary of the most recent and strongest constraints on QED with Lorentz violating non-renormalizable operators. Finally, we discuss the present status of the field and its future perspectives. (orig.)

Lorentz violation. Motivation and new constraints

International Nuclear Information System (INIS)

Liberati, S.; Maccione, L.

2009-09-01

We review the main theoretical motivations and observational constraints on Planck scale sup-pressed violations of Lorentz invariance. After introducing the problems related to the phenomenological study of quantum gravitational effects, we discuss the main theoretical frameworks within which possible departures from Lorentz invariance can be described. In particular, we focus on the framework of Effective Field Theory, describing several possible ways of including Lorentz violation therein and discussing their theoretical viability. We review the main low energy effects that are expected in this framework. We discuss the current observational constraints on such a framework, focusing on those achievable through high-energy astrophysics observations. In this context we present a summary of the most recent and strongest constraints on QED with Lorentz violating non-renormalizable operators. Finally, we discuss the present status of the field and its future perspectives. (orig.)

Constraint Differentiation

DEFF Research Database (Denmark)

Mödersheim, Sebastian Alexander; Basin, David; Viganò, Luca

2010-01-01

We introduce constraint differentiation, a powerful technique for reducing search when model-checking security protocols using constraint-based methods. Constraint differentiation works by eliminating certain kinds of redundancies that arise in the search space when using constraints to represent...... results show that constraint differentiation substantially reduces search and considerably improves the performance of OFMC, enabling its application to a wider class of problems....

Energy constraints and organizational change in US production

Energy Technology Data Exchange (ETDEWEB)

1980-12-01

There is still considerable uncertainty about the way in which energy-supply constraints affect industrial thinking and activity. Yet, this is an important issue in determining the effectiveness of conservation programs and in formulating energy policy. The authors expand on a survey of US business attitudes and responses to energy constraints first published in the September 1979 Energy Policy with the results of further analysis of their survey. In particular, they examine correlations between perceived causes and preferred solutions of energy problems, organizational adjustments to energy constraints in energy-intensive industries, and the ways in which production operations have changed in response to supply problems. 5 references, 5 tables.

Stochastic programming problems with generalized integrated chance constraints

Czech Academy of Sciences Publication Activity Database

Branda, Martin

2012-01-01

Roč. 61, č. 8 (2012), s. 949-968 ISSN 0233-1934 R&D Projects: GA ČR GAP402/10/1610 Grant - others:SVV(CZ) 261315/2010 Institutional support: RVO:67985556 Keywords : chance constraints * integrated chance constraints * penalty functions * sample approximations * blending problem Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.707, year: 2012 http://library.utia.cas.cz/separaty/2012/E/branda-stochastic programming problems with generalized integrated.pdf

Constraint-based scheduling applying constraint programming to scheduling problems

CERN Document Server

Baptiste, Philippe; Nuijten, Wim

2001-01-01

Constraint Programming is a problem-solving paradigm that establishes a clear distinction between two pivotal aspects of a problem: (1) a precise definition of the constraints that define the problem to be solved and (2) the algorithms and heuristics enabling the selection of decisions to solve the problem. It is because of these capabilities that Constraint Programming is increasingly being employed as a problem-solving tool to solve scheduling problems. Hence the development of Constraint-Based Scheduling as a field of study. The aim of this book is to provide an overview of the most widely used Constraint-Based Scheduling techniques. Following the principles of Constraint Programming, the book consists of three distinct parts: The first chapter introduces the basic principles of Constraint Programming and provides a model of the constraints that are the most often encountered in scheduling problems. Chapters 2, 3, 4, and 5 are focused on the propagation of resource constraints, which usually are responsibl...

Shrimp Feed Formulation via Evolutionary Algorithm with Power Heuristics for Handling Constraints

Directory of Open Access Journals (Sweden)

Rosshairy Abd. Rahman

2017-01-01

Full Text Available Formulating feed for shrimps represents a challenge to farmers and industry partners. Most previous studies selected from only a small number of ingredients due to cost pressures, even though hundreds of potential ingredients could be used in the shrimp feed mix. Even with a limited number of ingredients, the best combination of the most appropriate ingredients is still difficult to obtain due to various constraint requirements, such as nutrition value and cost. This paper proposes a new operator which we call Power Heuristics, as part of an Evolutionary Algorithm (EA, which acts as a constraint handling technique for the shrimp feed or diet formulation. The operator is able to choose and discard certain ingredients by utilising a specialized search mechanism. The aim is to achieve the most appropriate combination of ingredients. Power Heuristics are embedded in the EA at the early stage of a semirandom initialization procedure. The resulting combination of ingredients, after fulfilling all the necessary constraints, shows that this operator is useful in discarding inappropriate ingredients when a crucial constraint is violated.

Pair Production Constraints on Superluminal Neutrinos Revisited

International Nuclear Information System (INIS)

Brodsky, Stanley

2012-01-01

We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can evade the Cohen-Glashow constraint. In summary, any model for which the CG pair production process operates is excluded because such timelike neutrinos would not be detected by OPERA or other experiments. However, a superluminal neutrino which is effectively lightlike with fixed p 2 can evade the Cohen-Glashow constraint because of energy-momentum conservation. The coincidence involved in explaining the SN1987A constraint certainly makes such a picture improbable - but it is still intrinsically possible. The lightlike model is appealing in that it does not violate Lorentz symmetry in particle interactions, although one would expect Hughes-Drever tests to turn up a violation eventually. Other evasions of the CG constraints are also possible; perhaps, e.g., the neutrino takes a 'short cut' through extra dimensions or suffers anomalous acceleration in matter. Irrespective of the OPERA result, Lorentz-violating interactions remain possible, and ongoing experimental investigation of such possibilities should continue.

On Gupta-Bleuler quantization of systems with second-class constraints

International Nuclear Information System (INIS)

Kalau, Wolfgang.

1992-01-01

In this paper Hamiltonian systems with mixed first and second-class constraints are discussed. The authors prove that in a neighborhood of the constraint surface the complexified constraints can always be split into a holomorphic and an anti-holomorphic set, such that the holomorphic set can be implemented consistently on the ket-states of the corresponding quantum theory. The quantization is performed with BRSY-methods using a non-hermitian BRST-operator. As an example this method is used to quantize the 4-dimensional superparticle. (author). 25 refs

Assessing the Impact of Operational Constraints on the Near-Term Unmanned Aircraft System Traffic Management Supported Market

Science.gov (United States)

Vascik, Parker D.; Jung, Jaewoo

2016-01-01

An economic impact market analysis was conducted for 16 leading sectors of commercial Unmanned Aerial System (UAS) applications predicted to be enabled by 2020 through the NASA UAS Traffic Management (UTM) program. Subject matter experts from seven industries were interviewed to validate concept of operations (ConOps) and market adoption assumptions for each sector. The market analysis was used to estimate direct economic impacts for each sector including serviceable addressable market, capital investment, revenue recovery potential, and operations cost savings. The resultant economic picture distinguishes the agricultural, pipeline and railroad inspection, construction, and maritime sectors of the nascent commercial UAS industry as providing the highest potential economic value in the United States. Sensitivity studies characterized the variability of select UAS sectors economic value to key regulatory or UTM ConOps requirements such as weight, altitude, and flight over populated area constraints. Takeaways from the analysis inform the validation of UTM requirements, technologies and timetables from a commercial market need and value viewpoint. This work concluded in August 2015 and reflects the state of the UAS industry and market projections at that time.

Brain evolution and development: adaptation, allometry and constraint

Science.gov (United States)

Barton, Robert A.

2016-01-01

Phenotypic traits are products of two processes: evolution and development. But how do these processes combine to produce integrated phenotypes? Comparative studies identify consistent patterns of covariation, or allometries, between brain and body size, and between brain components, indicating the presence of significant constraints limiting independent evolution of separate parts. These constraints are poorly understood, but in principle could be either developmental or functional. The developmental constraints hypothesis suggests that individual components (brain and body size, or individual brain components) tend to evolve together because natural selection operates on relatively simple developmental mechanisms that affect the growth of all parts in a concerted manner. The functional constraints hypothesis suggests that correlated change reflects the action of selection on distributed functional systems connecting the different sub-components, predicting more complex patterns of mosaic change at the level of the functional systems and more complex genetic and developmental mechanisms. These hypotheses are not mutually exclusive but make different predictions. We review recent genetic and neurodevelopmental evidence, concluding that functional rather than developmental constraints are the main cause of the observed patterns. PMID:27629025

Constraints on relaxation rates for N-level quantum systems

International Nuclear Information System (INIS)

Schirmer, S.G.; Solomon, A.I.

2004-01-01

We study the constraints imposed on the population and phase relaxation rates by the physical requirement of completely positive evolution for open N-level systems. The Lindblad operators that govern the evolution of the system are expressed in terms of observable relaxation rates, explicit formulas for the decoherence rates due to population relaxation are derived, and it is shown that there are additional, nontrivial constraints on the pure dephasing rates for N>2. Explicit, experimentally testable inequality constraints for the decoherence rates are derived for three- and four-level systems, and the implications of the results are discussed for generic ladder, Λ, and V systems and transitions between degenerate energy levels

Ring power balance observing plasma stability constraints

International Nuclear Information System (INIS)

Campbell, R.B.; Logan, B.G.

1982-01-01

Ring power balance is performed for an E-ring stabilized tandem mirror reactor, taking into account constraints imposed by plasma stability. The two most important criteria are the stability of the core interchange and hot electron interchange modes. The former determines the ring thickness, the latter determines the minimum hot electron temperature; both quantities are important for power balance. The combination of the hot electron interchange constraint and the fact that the barrier density is low places the operating point on the synchrotron dominated branch of power balance. The reference case considered here requires a reasonable 34 MW of heating power deposited in the rings. We also have examined the sensitivity of the required ring power on uncertainties in the numerical coefficients of the stability constraints. We have found that the heating power is strongly affected

Reactor operating procedures for start up of continuously operated chemical plants

NARCIS (Netherlands)

Verwijs, J.W.; Verwijs, J.W.; Kösters, P.H.; van den Berg, Henderikus; Westerterp, K.R.; Kosters, P.G.H.

1995-01-01

Rules are presented for the startup of an adiabatic tubular reactor, based on a qualitative analysis of the dynamic behavior of continuously-operated vapor- and liquid-phase processes. The relationships between the process dynamics, operating criteria, and operating constraints are investigated,

Modifier constraint in alkali borophosphate glasses using topological constraint theory

Energy Technology Data Exchange (ETDEWEB)

Li, Xiang [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zeng, Huidan, E-mail: hdzeng@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Jiang, Qi [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhao, Donghui [Unifrax Corporation, Niagara Falls, NY 14305 (United States); Chen, Guorong [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Wang, Zhaofeng; Sun, Luyi [Department of Chemical & Biomolecular Engineering and Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Chen, Jianding [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2016-12-01

In recent years, composition-dependent properties of glasses have been successfully predicted using the topological constraint theory. The constraints of the glass network are derived from two main parts: network formers and network modifiers. The constraints of the network formers can be calculated on the basis of the topological structure of the glass. However, the latter cannot be accurately calculated in this way, because of the existing of ionic bonds. In this paper, the constraints of the modifier ions in phosphate glasses were thoroughly investigated using the topological constraint theory. The results show that the constraints of the modifier ions are gradually increased with the addition of alkali oxides. Furthermore, an improved topological constraint theory for borophosphate glasses is proposed by taking the composition-dependent constraints of the network modifiers into consideration. The proposed theory is subsequently evaluated by analyzing the composition dependence of the glass transition temperature in alkali borophosphate glasses. This method is supposed to be extended to other similar glass systems containing alkali ions.

Quasivariational Solutions for First Order Quasilinear Equations with Gradient Constraint

Science.gov (United States)

Rodrigues, José Francisco; Santos, Lisa

2012-08-01

We prove the existence of solutions for a quasi-variational inequality of evolution with a first order quasilinear operator and a variable convex set which is characterized by a constraint on the absolute value of the gradient that depends on the solution itself. The only required assumption on the nonlinearity of this constraint is its continuity and positivity. The method relies on an appropriate parabolic regularization and suitable a priori estimates. We also obtain the existence of stationary solutions by studying the asymptotic behaviour in time. In the variational case, corresponding to a constraint independent of the solution, we also give uniqueness results.

Design constraints for electron-positron linear colliders

International Nuclear Information System (INIS)

Mondelli, A.; Chernin, D.

1991-01-01

A prescription for examining the design constraints in the e + -e - linear collider is presented. By specifying limits on certain key quantities, an allowed region of parameter space can be presented, hopefully clarifying some of the design options. The model starts with the parameters at the interaction point (IP), where the expressions for the luminosity, the disruption parameter, beamstrahlung, and average beam power constitute four relations among eleven IP parameters. By specifying the values of five of these quantities, and using these relationships, the unknown parameter space can be reduced to a two-dimensional space. Curves of constraint can be plotted in this space to define an allowed operating region. An accelerator model, based on a modified, scaled SLAC structure, can then be used to derive the corresponding parameter space including the constraints derived from power consumption and wake field effects. The results show that longer, lower gradient accelerators are advantageous

Graphical constraints: a graphical user interface for constraint problems

OpenAIRE

Vieira, Nelson Manuel Marques

2015-01-01

A constraint satisfaction problem is a classical artificial intelligence paradigm characterized by a set of variables (each variable with an associated domain of possible values), and a set of constraints that specify relations among subsets of these variables. Solutions are assignments of values to all variables that satisfy all the constraints. Many real world problems may be modelled by means of constraints. The range of problems that can use this representation is very diverse and embrace...

Minimal investment risk of a portfolio optimization problem with budget and investment concentration constraints

Science.gov (United States)

Shinzato, Takashi

2017-02-01

In the present paper, the minimal investment risk for a portfolio optimization problem with imposed budget and investment concentration constraints is considered using replica analysis. Since the minimal investment risk is influenced by the investment concentration constraint (as well as the budget constraint), it is intuitive that the minimal investment risk for the problem with an investment concentration constraint can be larger than that without the constraint (that is, with only the budget constraint). Moreover, a numerical experiment shows the effectiveness of our proposed analysis. In contrast, the standard operations research approach failed to identify accurately the minimal investment risk of the portfolio optimization problem.

Fundamental constraints on some event data

International Nuclear Information System (INIS)

Watson, I.A.

1986-01-01

A modified version of Searle's theory of the structure of human action has been explained and applied to man machine interaction. The comprehensiveness of the theory has been demonstrated, in particular its explanation of human performance and that its consistency with current theories of human error for which it provides an overall setting. The importance of the mental component of human error is highlighted and the constraints that this puts on the collection analysis and use of human error data. Examples have been given to illustrate and apply the theory ranging from considerations of the tenuousness of the link between safety goals and data to simple valve operations. Two approaches which recognise the constraints shown by the theory have been explained. (orig./DG)

Interactive orbital proximity operations planning system

Science.gov (United States)

Grunwald, Arthur J.; Ellis, Stephen R.

1990-01-01

An interactive graphical planning system for on-site planning of proximity operations in the congested multispacecraft environment about the space station is presented. The system shows the astronaut a bird's eye perspective of the space station, the orbital plane, and the co-orbiting spacecraft. The system operates in two operational modes: (1) a viewpoint mode, in which the astronaut is able to move the viewpoint around in the orbital plane to range in on areas of interest; and (2) a trajectory design mode, in which the trajectory is planned. Trajectory design involves the composition of a set of waypoints which result in a fuel-optimal trajectory which satisfies all operational constraints, such as departure and arrival constraints, plume impingement constraints, and structural constraints. The main purpose of the system is to present the trajectory and the constraints in an easily interpretable graphical format. Through a graphical interactive process, the trajectory waypoints are edited until all operational constraints are satisfied. A series of experiments was conducted to evaluate the system. Eight airline pilots with no prior background in orbital mechanics participated in the experiments. Subject training included a stand-alone training session of about 6 hours duration, in which the subjects became familiar with orbital mechanics concepts and performed a series of exercises to familiarize themselves with the control and display features of the system. They then carried out a series of production runs in which 90 different trajectory design situations were randomly addressed. The purpose of these experiments was to investigate how the planning time, planning efforts, and fuel expenditures were affected by the planning difficulty. Some results of these experiments are presented.

Export constraints facing Lesotho-based manufacturing enterprises

Directory of Open Access Journals (Sweden)

Motšelisi C. Mokhethi

2015-07-01

Full Text Available Orientation: Exporting is preferred by many enterprises as the mode of foreign entry as it requires less commitment of organisational resources and offers flexibility of managerial actions. However, enterprises face a number of challenges when attempting to initiate exports or expand their export operations. Research purpose: This study was undertaken to determine the characteristics and composition of export barriers constraining exporting by Lesotho-based manufacturing enterprises. Motivation for the study: Lesotho is faced with low destination diversity and low diversity in export products. Research design, approach and method: Data was collected from 162 Lesotho-based manufacturing enterprises through a self-administered questionnaire. Main findings: In its findings, the study firstly identified international constraints, distribution constraints and financial constraints as factors constraining exporting. Secondly, it was determined that three exporting constraints, all internal to the enterprise and all related to one factor (namely financial constraint hampered exporting. Lastly, the ANOVA results revealed that the perceptions of export constraints differed according to the enterprise characteristics, enterprise size, ownership and type of industry. Contribution/value-add: With the majority of enterprises in this study being identified as micro-enterprises, the government of Lesotho needs to pay particular attention to addressing the export needs of these enterprises in order to enable them to participate in exporting activities − especially considering that they can play a pivotal role in the alleviation of poverty, job creation and economic rejuvenation.

Creativity within constraints: Encoding, production, and representation in Battlestar Galactica

OpenAIRE

Adams, Philippa Rush

2015-01-01

Using the lens of feminist production studies, I examine the television show Battlestar Galactica through interviews with show creators to explore the contexts of production. Writers, actors, and producers experience constraints on their creativity. Media producers encode meaning into the texts they create and form their own understandings of social issues and stories. I examine the day-to-day processes and constraints operating in the work lives of television creators as well as their politi...

Some general constraints on identical band symmetries

International Nuclear Information System (INIS)

Guidry, M.W.; Strayer, M.R.; Wu, C.; Feng, D.H.

1993-01-01

We argue on general grounds that nearly identical bands observed for superdeformation and less frequently for normal deformation must be explicable in terms of a symmetry having a microscopic basis. We assume that the unknown symmetry is associated with a Lie algebra generated by terms bilinear in fermion creation and annihilation operators. Observed features of these bands and the general properties of Lie groups are then used to place constraints on acceptable algebras. Additional constraints are placed by assuming that the collective spectrum is associated with a dynamical symmetry, and examining the subgroup structure required by phenomenology. We observe that requisite symmetry cannot be unitary, and that the simplest known group structures consistent with these minimal criteria are associated with the Ginocchio algebras employed in the fermion dynamical symmetry model. However, our arguments are general in nature, and we propose that they imply model-independent constraints on any candidate explanation for identical bands

Approximate Compilation of Constraints into Multivalued Decision Diagrams

DEFF Research Database (Denmark)

Hadzic, Tarik; Hooker, John N.; O’Sullivan, Barry

2008-01-01

We present an incremental refinement algorithm for approximate compilation of constraint satisfaction models into multivalued decision diagrams (MDDs). The algorithm uses a vertex splitting operation that relies on the detection of equivalent paths in the MDD. Although the algorithm is quite gene...

Analysis of Space Tourism Constraints

Science.gov (United States)

Bonnal, Christophe

2002-01-01

Space tourism appears today as a new Eldorado in a relatively near future. Private operators are already proposing services for leisure trips in Low Earth Orbit, and some happy few even tested them. But are these exceptional events really marking the dawn of a new space age ? The constraints associated to the space tourism are severe : - the economical balance of space tourism is tricky; development costs of large manned - the technical definition of such large vehicles is challenging, mainly when considering - the physiological aptitude of passengers will have a major impact on the mission - the orbital environment will also lead to mission constraints on aspects such as radiation, However, these constraints never appear as show-stoppers and have to be dealt with pragmatically: - what are the recommendations one can make for future research in the field of space - which typical roadmap shall one consider to develop realistically this new market ? - what are the synergies with the conventional missions and with the existing infrastructure, - how can a phased development start soon ? The paper proposes hints aiming at improving the credibility of Space Tourism and describes the orientations to follow in order to solve the major hurdles found in such an exciting development.

Acquisition of the Constraints on "Wanna" Contraction by Advanced Second Language Learners: Universal Grammar and Imperfect Knowledge

Science.gov (United States)

Kweon, Soo-Ok; Bley-Vroman, Robert

2011-01-01

Contraction of "want to" to "wanna" is subject to constraints that have been related to the operation of Universal Grammar. Contraction appears to be blocked when the trace of an extracted "wh"-word intervenes. Evidence for knowledge of these constraints by young English-speaking children has been taken to show the operation of Universal Grammar…

Soft Budget Constraints in Professional Football

DEFF Research Database (Denmark)

Storm, Rasmus K.; Nielsen, Klaus

2012-01-01

European professional football clubs go out of business even though they operate chronically on the edge of financial collapse? The paper argues that the paradox can be explained by the fact that professional football clubs operate within soft budget constraints in a way which is similar to the role...... of large companies in socialist economies – a phenomenon which was first identified by the Hungarian Economist János Kornai. More generally, it is argued that our understanding of the peculiar economics of professional team sports can be enhanced significantly by applying the soft budget constrain concept...

Constrained Optimization Based on Hybrid Evolutionary Algorithm and Adaptive Constraint-Handling Technique

DEFF Research Database (Denmark)

Wang, Yong; Cai, Zixing; Zhou, Yuren

2009-01-01

A novel approach to deal with numerical and engineering constrained optimization problems, which incorporates a hybrid evolutionary algorithm and an adaptive constraint-handling technique, is presented in this paper. The hybrid evolutionary algorithm simultaneously uses simplex crossover and two...... mutation operators to generate the offspring population. Additionally, the adaptive constraint-handling technique consists of three main situations. In detail, at each situation, one constraint-handling mechanism is designed based on current population state. Experiments on 13 benchmark test functions...... and four well-known constrained design problems verify the effectiveness and efficiency of the proposed method. The experimental results show that integrating the hybrid evolutionary algorithm with the adaptive constraint-handling technique is beneficial, and the proposed method achieves competitive...

Modeling external constraints: Applying expert systems to nuclear plants

International Nuclear Information System (INIS)

Beck, C.E.; Behera, A.K.

1993-01-01

Artificial Intelligence (AI) applications in nuclear plants have received much attention over the past decade. Specific applications that have been addressed include development of models and knowledge-bases, plant maintenance, operations, procedural guidance, risk assessment, and design tools. This paper examines the issue of external constraints, with a focus on the use of Al and expert systems as design tools. It also provides several suggested methods for addressing these constraints within the Al framework. These methods include a State Matrix scheme, a layered structure for the knowledge base, and application of the dynamic parameter concept

From physical dose constraints to equivalent uniform dose constraints in inverse radiotherapy planning

International Nuclear Information System (INIS)

Thieke, Christian; Bortfeld, Thomas; Niemierko, Andrzej; Nill, Simeon

2003-01-01

Optimization algorithms in inverse radiotherapy planning need information about the desired dose distribution. Usually the planner defines physical dose constraints for each structure of the treatment plan, either in form of minimum and maximum doses or as dose-volume constraints. The concept of equivalent uniform dose (EUD) was designed to describe dose distributions with a higher clinical relevance. In this paper, we present a method to consider the EUD as an optimization constraint by using the method of projections onto convex sets (POCS). In each iteration of the optimization loop, for the actual dose distribution of an organ that violates an EUD constraint a new dose distribution is calculated that satisfies the EUD constraint, leading to voxel-based physical dose constraints. The new dose distribution is found by projecting the current one onto the convex set of all dose distributions fulfilling the EUD constraint. The algorithm is easy to integrate into existing inverse planning systems, and it allows the planner to choose between physical and EUD constraints separately for each structure. A clinical case of a head and neck tumor is optimized using three different sets of constraints: physical constraints for all structures, physical constraints for the target and EUD constraints for the organs at risk, and EUD constraints for all structures. The results show that the POCS method converges stable and given EUD constraints are reached closely

A note on a model for quay crane scheduling with non-crossing constraints

DEFF Research Database (Denmark)

Santini, Alberto; Friberg, Henrik Alsing; Røpke, Stefan

2015-01-01

This article studies the quay crane scheduling problem with non-crossing constraints, which is an operational problem that arises in container terminals. An enhancement to a mixed integer programming model for the problem is proposed and a new class of valid inequalities is introduced. Computatio......This article studies the quay crane scheduling problem with non-crossing constraints, which is an operational problem that arises in container terminals. An enhancement to a mixed integer programming model for the problem is proposed and a new class of valid inequalities is introduced...

Constraint-based reachability

Directory of Open Access Journals (Sweden)

Arnaud Gotlieb

2013-02-01

Full Text Available Iterative imperative programs can be considered as infinite-state systems computing over possibly unbounded domains. Studying reachability in these systems is challenging as it requires to deal with an infinite number of states with standard backward or forward exploration strategies. An approach that we call Constraint-based reachability, is proposed to address reachability problems by exploring program states using a constraint model of the whole program. The keypoint of the approach is to interpret imperative constructions such as conditionals, loops, array and memory manipulations with the fundamental notion of constraint over a computational domain. By combining constraint filtering and abstraction techniques, Constraint-based reachability is able to solve reachability problems which are usually outside the scope of backward or forward exploration strategies. This paper proposes an interpretation of classical filtering consistencies used in Constraint Programming as abstract domain computations, and shows how this approach can be used to produce a constraint solver that efficiently generates solutions for reachability problems that are unsolvable by other approaches.

Constraint-Muse: A Soft-Constraint Based System for Music Therapy

Science.gov (United States)

Hölzl, Matthias; Denker, Grit; Meier, Max; Wirsing, Martin

Monoidal soft constraints are a versatile formalism for specifying and solving multi-criteria optimization problems with dynamically changing user preferences. We have developed a prototype tool for interactive music creation, called Constraint Muse, that uses monoidal soft constraints to ensure that a dynamically generated melody harmonizes with input from other sources. Constraint Muse provides an easy to use interface based on Nintendo Wii controllers and is intended to be used in music therapy for people with Parkinson’s disease and for children with high-functioning autism or Asperger’s syndrome.

Technology for planning and scheduling under complex constraints

Science.gov (United States)

Alguire, Karen M.; Pedro Gomes, Carla O.

1997-02-01

Within the context of law enforcement, several problems fall into the category of planning and scheduling under constraints. Examples include resource and personnel scheduling, and court scheduling. In the case of court scheduling, a schedule must be generated considering available resources, e.g., court rooms and personnel. Additionally, there are constraints on individual court cases, e.g., temporal and spatial, and between different cases, e.g., precedence. Finally, there are overall objectives that the schedule should satisfy such as timely processing of cases and optimal use of court facilities. Manually generating a schedule that satisfies all of the constraints is a very time consuming task. As the number of court cases and constraints increases, this becomes increasingly harder to handle without the assistance of automatic scheduling techniques. This paper describes artificial intelligence (AI) technology that has been used to develop several high performance scheduling applications including a military transportation scheduler, a military in-theater airlift scheduler, and a nuclear power plant outage scheduler. We discuss possible law enforcement applications where we feel the same technology could provide long-term benefits to law enforcement agencies and their operations personnel.

Iterative Repair Planning for Spacecraft Operations Using the Aspen System

Science.gov (United States)

Rabideau, G.; Knight, R.; Chien, S.; Fukunaga, A.; Govindjee, A.

2000-01-01

This paper describes the Automated Scheduling and Planning Environment (ASPEN). ASPEN encodes complex spacecraft knowledge of operability constraints, flight rules, spacecraft hardware, science experiments and operations procedures to allow for automated generation of low level spacecraft sequences. Using a technique called iterative repair, ASPEN classifies constraint violations (i.e., conflicts) and attempts to repair each by performing a planning or scheduling operation. It must reason about which conflict to resolve first and what repair method to try for the given conflict. ASPEN is currently being utilized in the development of automated planner/scheduler systems for several spacecraft, including the UFO-1 naval communications satellite and the Citizen Explorer (CX1) satellite, as well as for planetary rover operations and antenna ground systems automation. This paper focuses on the algorithm and search strategies employed by ASPEN to resolve spacecraft operations constraints, as well as the data structures for representing these constraints.

Automated constraint placement to maintain pile shape

KAUST Repository

Hsu, Shu-Wei

2012-11-01

We present a simulation control to support art-directable stacking designs by automatically adding constraints to stabilize the stacking structure. We begin by adapting equilibrium analysis in a local scheme to find "stable" objects of the stacking structure. Next, for stabilizing the structure, we pick suitable objects from those passing the equilibrium analysis and then restrict their DOFs by managing the insertion of constraints on them. The method is suitable for controlling stacking behavior of large scale. Results show that our control method can be used in varied ways for creating plausible animation. In addition, the method can be easily implemented as a plug-in into existing simulation solvers without changing the fundamental operations of the solvers. © 2012 ACM.

Combining Market-Based Control with Distribution Grid Constraints when Coordinating Electric Vehicle Charging

Directory of Open Access Journals (Sweden)

Geert Deconinck

2015-12-01

Full Text Available The charging of electric vehicles (EVs impacts the distribution grid, and its cost depends on the price of electricity when charging. An aggregator that is responsible for a large fleet of EVs can use a market-based control algorithm to coordinate the charging of these vehicles, in order to minimize the costs. In such an optimization, the operational parameters of the distribution grid, to which the EVs are connected, are not considered. This can lead to violations of the technical constraints of the grid (e.g., under-voltage, phase unbalances; for example, because many vehicles start charging simultaneously when the price is low. An optimization that simultaneously takes the economic and technical aspects into account is complex, because it has to combine time-driven control at the market level with event-driven control at the operational level. Different case studies investigate under which circumstances the market-based control, which coordinates EV charging, conflicts with the operational constraints of the distribution grid. Especially in weak grids, phase unbalance and voltage issues arise with a high share of EVs. A low-level voltage droop controller at the charging point of the EV can be used to avoid many grid constraint violations, by reducing the charge power if the local voltage is too low. While this action implies a deviation from the cost-optimal operating point, it is shown that this has a very limited impact on the business case of an aggregator, and is able to comply with the technical distribution grid constraints, even in weak distribution grids with many EVs.

New Constraints on Dark Matter Effective Theories from Standard Model Loops

CERN Document Server

Crivellin, Andreas; Procura, Massimiliano

2014-01-01

We consider an effective field theory for a gauge singlet Dirac dark matter (DM) particle interacting with the Standard Model (SM) fields via effective operators suppressed by the scale $\\Lambda \\gtrsim 1$ TeV. We perform a systematic analysis of the leading loop contributions to spin-independent (SI) DM--nucleon scattering using renormalization group evolution between $\\Lambda$ and the low-energy scale probed by direct detection experiments. We find that electroweak interactions induce operator mixings such that operators that are naively velocity-suppressed and spin-dependent can actually contribute to SI scattering. This allows us to put novel constraints on Wilson coefficients that were so far poorly bounded by direct detection. Constraints from current searches are comparable to LHC bounds, and will significantly improve in the near future. Interestingly, the loop contribution we find is maximally isospin violating even if the underlying theory is isospin conserving.

Lageos assembly operation plan

Science.gov (United States)

Brueger, J.

1975-01-01

Guidelines and constraints procedures for LAGEOS assembly, operation, and design performance are given. Special attention was given to thermal, optical, and dynamic analysis and testing. The operation procedures illustrate the interrelation and sequence of tasks in a flow diagram. The diagram also includes quality assurance functions for verification of operation tasks.

Schwinger-Dyson loop equations as the w1+∞-like constraints for hermitian multi-matrix chain model at finite N

International Nuclear Information System (INIS)

Cheng, Yi-Xin

1992-01-01

The Schwinger-Dyson loop equations for the hermitian multi-matrix chain models at finite N, are derived from the Ward identities of the partition functional under the infinitesimal field transformations. The constraint operators W n (m) satisfy the w 1+∞ -like algebra up to a linear combination of the lower spin operators. We find that the all the higher spin constraints are reducible to the Virasoro-type constraints for all the matrix chain models. (author)

Imposing motion constraints to a force reflecting tele-robot through real-time simulation of a virtual mechanism

Energy Technology Data Exchange (ETDEWEB)

Joly, L.; Andriot, C.

1995-12-31

In a tele-operation system, assistance can be given to the operator by constraining the tele-robot position to remain within a restricted subspace of its workspace. A new approach to motion constraint is presented in this paper. The control law is established simulating a virtual ideal mechanism acting as a jig, and connected to the master and slave arms via springs and dampers. Using this approach, it is possible to impose any (sufficiently smooth) motion constraint to the system, including non linear constraints (complex surfaces) involving coupling between translations and rotations and physical equivalence ensures that the controller is passive. Experimental results obtained with a 6-DOF tele-operation system are given. Other applications of the virtual mechanism concept include hybrid position-force control and haptic interfaces. (authors). 11 refs., 7 figs.

Imposing motion constraints to a force reflecting tele-robot through real-time simulation of a virtual mechanism

International Nuclear Information System (INIS)

Joly, L.; Andriot, C.

1995-01-01

In a tele-operation system, assistance can be given to the operator by constraining the tele-robot position to remain within a restricted subspace of its workspace. A new approach to motion constraint is presented in this paper. The control law is established simulating a virtual ideal mechanism acting as a jig, and connected to the master and slave arms via springs and dampers. Using this approach, it is possible to impose any (sufficiently smooth) motion constraint to the system, including non linear constraints (complex surfaces) involving coupling between translations and rotations and physical equivalence ensures that the controller is passive. Experimental results obtained with a 6-DOF tele-operation system are given. Other applications of the virtual mechanism concept include hybrid position-force control and haptic interfaces. (authors). 11 refs., 7 figs

Testing the master constraint programme for loop quantum gravity: V. Interacting field theories

International Nuclear Information System (INIS)

Dittrich, B; Thiemann, T

2006-01-01

This is the fifth and final paper in our series of five in which we test the master constraint programme for solving the Hamiltonian constraint in loop quantum gravity. Here we consider interacting quantum field theories, specifically we consider the non-Abelian Gauss constraints of Einstein-Yang-Mills theory and 2 + 1 gravity. Interestingly, while Yang-Mills theory in 4D is not yet rigorously defined as an ordinary (Wightman) quantum field theory on Minkowski space, in background-independent quantum field theories such as loop quantum gravity (LQG) this might become possible by working in a new, background-independent representation. While for the Gauss constraint the master constraint can be solved explicitly, for the 2 + 1 theory we are only able to rigorously define the master constraint operator. We show that the, by other methods known, physical Hilbert is contained in the kernel of the master constraint, however, to systematically derive it by only using spectral methods is as complicated as for 3 + 1 gravity and we therefore leave the complete analysis for 3 + 1 gravity

Main physics features driving design concept and physics design constraints

International Nuclear Information System (INIS)

Fujisawa, Noboru; Sugihara, Masayoshi; Yamamoto, Shin

1987-07-01

Major physics design philosophies are described, which are essential bases for a plasma design and may have significant impacts on a reactor design concept. Those design philosophies are classified into two groups, physics design drivers and physics design constraints. The design drivers are featured by the fact that a designer is free to choose and the choice may be guided by his opinion, such as ignition, a pulse length, an operation scenario, etc.. The design constraints may follow a physical law, such as plasma confinement, β-limit, density limit, and so on. (author)

Momentum constraint relaxation

International Nuclear Information System (INIS)

Marronetti, Pedro

2006-01-01

Full relativistic simulations in three dimensions invariably develop runaway modes that grow exponentially and are accompanied by violations of the Hamiltonian and momentum constraints. Recently, we introduced a numerical method (Hamiltonian relaxation) that greatly reduces the Hamiltonian constraint violation and helps improve the quality of the numerical model. We present here a method that controls the violation of the momentum constraint. The method is based on the addition of a longitudinal component to the traceless extrinsic curvature A ij -tilde, generated by a vector potential w i , as outlined by York. The components of w i are relaxed to solve approximately the momentum constraint equations, slowly pushing the evolution towards the space of solutions of the constraint equations. We test this method with simulations of binary neutron stars in circular orbits and show that it effectively controls the growth of the aforementioned violations. We also show that a full numerical enforcement of the constraints, as opposed to the gentle correction of the momentum relaxation scheme, results in the development of instabilities that stop the runs shortly

Land application of waste waters in the Alligator Rivers region, Northern Territory - environmental constraints on design and operation

International Nuclear Information System (INIS)

Kearns, A.

1986-01-01

The existing uranium mines in the Alligator River Region presently operate under a no release water management regime for water stored within the designated restricted release zones (RRZ). This water is of variable quality ranging from rainwater influenced by runoff from the mill sites and ore stockpiles to mill process water stored within the trailings repositories. There is a pressing need to reduce the volume of stored RRZ water at Nabarlek as a prerequisite to decommissioning. There is also a requirement at Ranger to rapidly reduce the volume of stored water in the mine pit at the end of the season to allow the mining of ore. Land application of RRZ water by spray irrigation has been investigated at both sites because it offers the benefits of applying chemical constituents in the wastewater within a clearly defined irrigation area. the environmental planning for the design of a land application system involves calculations of the chemical load in the wastewater and evaluation of the assimilative capacity of the soil-plant system. The monsoon climate, lateritic soil and fluctuating water table creates a unique set of environmental constraints and conditions in which to design and operate a successful land application system for the treatment of stored water at minesites within ecologically sensitive areas

Electrical constraints on electronic components: syntheses of the ETTC'97 and RADECS 97 congress activities

International Nuclear Information System (INIS)

Carel, Ch.

1998-01-01

The electromagnetic compatibility (EMC) of systems and their hardening against electromagnetic (IEMN, lightning, strong radio and radar fields..) and radiative environments impose severe manufacturing constraints in competition with other functional constraints, like thermal constraints and weight, and operational constraints (maintenance, availability). This paper is a summary of the main topics discussed during the ETTC and RADECS 1997 congresses. The outstanding facts concern: the non-disturbance of components (hyper-frequency EMC and high fields), the non-destruction of components (hardening against electromagnetic pulses), the civil domain, the numerical simulations, the integrity of electronic card signals, and the reliability of components. (J.S.)

Design and Validation of a Control Algorithm for a SAE J2954-Compliant Wireless Charger to Guarantee the Operational Electrical Constraints

Directory of Open Access Journals (Sweden)

José Manuel González-González

2018-03-01

Full Text Available Wireless power transfer is foreseen as a suitable technology to provide charge without cables to electric vehicles. This technology is mainly supported by two coupled coils, whose mutual inductance is sensitive to their relative positions. Variations on this coefficient greatly impact the electrical magnitudes of the wireless charger. The aim of this paper is the design and validation of a control algorithm for an Society of Automotive Engineers (SAE J2954-compliant wireless charger to guarantee some operational and electrical constraints. These constraints are designed to prevent some components from being damaged by excessive voltage or current. This paper also presents the details for the design and implementation of the bidirectional charger topology in which the proposed controller is incorporated. The controller is installed on the primary and on the secondary side, given that wireless communication is necessary with the other side. The input data of the controller helps it decide about the phase shift required to apply in the DC/AC converter. The experimental results demonstrate how the system regulates the output voltage of the DC/AC converter so that some electrical magnitudes do not exceed predefined thresholds. The regulation, which has been tested when coil misalignments occur, is proven to be effective.

On the covariantization of the Chiral constraints

International Nuclear Information System (INIS)

Wotzasek, Clovis; Abreu, E.M.C. de; Neves, C.

1994-01-01

We show that a complete covariantization of the chiral constraint in the Floreanini-Jackiw necessitates an infinite number of auxiliary Wess-Zumino fields otherwise the covariantization is only partial and unable to remove the nonlocality in the chiral boson operator. We comment on recent works that claim to obtain covariantization through the use of Batalin-Fradklin-Tyutin method, that uses just one Wess-Zumino field. (author)

Periodic capacity management under a lead-time performance constraint

NARCIS (Netherlands)

Büyükkaramikli, N.C.; Bertrand, J.W.M.; Ooijen, van H.P.G.

2013-01-01

In this paper, we study a production system that operates under a lead-time performance constraint which guarantees the completion of an order before a pre-determined lead-time with a certain probability. The demand arrival times and the service requirements for the orders are random. To reduce the

A Safe Supervisory Flight Control Scheme in the Presence of Constraints and Anomalies

Directory of Open Access Journals (Sweden)

Franzè Giuseppe

2015-03-01

Full Text Available In this paper the hybrid supervisory control architecture developed by Famularo et al. (2011 for constrained control systems is adopted with the aim to improve safety in aircraft operations when critical events like command saturations or unpredicted anomalies occur. The capabilities of a low-computational demanding predictive scheme for the supervision of non-linear dynamical systems subject to sudden switchings amongst operating conditions and time-varying constraints are exploited in the flight control systems framework. The strategy is based on command governor ideas and is tailored to jointly take into account time-varying set-points/constraints. Unpredictable anomalies in the nominal plant behaviour, whose models fall in the category of time-varying constraints, can also be tolerated by the control scheme. In order to show the effectiveness of the proposed approach, simulations both on a high altitude performance demonstrator unmanned aircraft with redundant control surfaces and the P92 general aviation aircraft are discussed.

Reducing constraints on quantum computer design by encoded selective recoupling

International Nuclear Information System (INIS)

Lidar, D.A.; Wu, L.-A.

2002-01-01

The requirement of performing both single-qubit and two-qubit operations in the implementation of universal quantum logic often leads to very demanding constraints on quantum computer design. We show here how to eliminate the need for single-qubit operations in a large subset of quantum computer proposals: those governed by isotropic and XXZ , XY -type anisotropic exchange interactions. Our method employs an encoding of one logical qubit into two physical qubits, while logic operations are performed using an analogue of the NMR selective recoupling method

Analysis of differences in exercise recognition by constraints on physical activity of hospitalized cancer patients based on their medical history.

Science.gov (United States)

Choi, Mi-Ri; Jeon, Sang-Wan; Yi, Eun-Surk

2018-04-01

The purpose of this study is to analyze the differences among the hospitalized cancer patients on their perception of exercise and physical activity constraints based on their medical history. The study used questionnaire survey as measurement tool for 194 cancer patients (male or female, aged 20 or older) living in Seoul metropolitan area (Seoul, Gyeonggi, Incheon). The collected data were analyzed using frequency analysis, exploratory factor analysis, reliability analysis t -test, and one-way distribution using statistical program SPSS 18.0. The following results were obtained. First, there was no statistically significant difference between cancer stage and exercise recognition/physical activity constraint. Second, there was a significant difference between cancer stage and sociocultural constraint/facility constraint/program constraint. Third, there was a significant difference between cancer operation history and physical/socio-cultural/facility/program constraint. Fourth, there was a significant difference between cancer operation history and negative perception/facility/program constraint. Fifth, there was a significant difference between ancillary cancer treatment method and negative perception/facility/program constraint. Sixth, there was a significant difference between hospitalization period and positive perception/negative perception/physical constraint/cognitive constraint. In conclusion, this study will provide information necessary to create patient-centered healthcare service system by analyzing exercise recognition of hospitalized cancer patients based on their medical history and to investigate the constraint factors that prevents patients from actually making efforts to exercise.

The real economic effects of cross-delisting from the United States: Evidence on post-operating performance, financial constraints and stock crash risk =

Science.gov (United States)

Silva, Sonia Maria da Silva Faria Nogueira da

In this study we examine the economic consequences for firms that cross-delisted from a U.S. stock exchange. Using a sample of foreign firms that cross-delisted from U.S. exchange markets from 2000 to 2012, we investigate the long-term performance, the level of financial constraints, and the likelihood of stock price crashes after the cross-delisting event. We document several new findings as follows: i) cross-delisted firms have less growth opportunities, in the long-run, than their cross-listed peers; ii) after the adoption of Rule 12h-6 of 2007, cross-delisted firms exhibit a significant decline in operating performance; iii) cross-delisted firms underperform their cross-listed peers as they experience negative average abnormal returns, especially in the post-cross-delisting period; iv) cross-delisted firms face higher financial constraints post-delisting than their cross-listed counterparts, and also tend to save more cash out of cash flows; v) the increase in financial constraints post-cross-delisting seems to be primarily driven by informational frictions that constrain access to external financing, which are stronger for firms from countries with weaker investor protection and less developed capital markets; vi) cross-delisted firms experience a significant increase in crash risk associated with earnings management in the post-delisting period relative to a control sample of cross-listed firms, and this effect is more pronounced for delisted firms from countries with weaker investor protection and poor quality of their information environment; vii) cross-delisted firms that engage in earnings management to inflate reported earnings prior to a seasoned equity offering are more likely to a subsequent stock price crash.

A Linear Programming Approach to the Development of Contrail Reduction Strategies Satisfying Operationally Feasible Constraints

Science.gov (United States)

Wei, Peng; Sridhar, Banavar; Chen, Neil Yi-Nan; Sun, Dengfent

2012-01-01

A class of strategies has been proposed to reduce contrail formation in the United States airspace. A 3D grid based on weather data and the cruising altitude level of aircraft is adjusted to avoid the persistent contrail potential area with the consideration to fuel-efficiency. In this paper, the authors introduce a contrail avoidance strategy on 3D grid by considering additional operationally feasible constraints from an air traffic controller's aspect. First, shifting too many aircraft to the same cruising level will make the miles-in-trail at this level smaller than the safety separation threshold. Furthermore, the high density of aircraft at one cruising level may exceed the workload for the traffic controller. Therefore, in our new model we restrict the number of total aircraft at each level. Second, the aircraft count variation for successive intervals cannot be too drastic since the workload to manage climbing/descending aircraft is much larger than managing cruising aircraft. The contrail reduction is formulated as an integer-programming problem and the problem is shown to have the property of total unimodularity. Solving the corresponding relaxed linear programming with the simplex method provides an optimal and integral solution to the problem. Simulation results are provided to illustrate the methodology.

Procedural Design of Exterior Lighting for Buildings with Complex Constraints

KAUST Repository

Schwarz, Michael

2014-10-01

We present a system for the lighting design of procedurally modeled buildings. The design is procedurally specified as part of the ordinary modeling workflow by defining goals for the illumination that should be attained and locations where luminaires may be installed to realize these goals. Additionally, constraints can be modeled that make the arrangement of the installed luminaires respect certain aesthetic and structural considerations. From this specification, the system automatically generates a lighting solution for any concrete model instance. The underlying, intricate joint optimization and constraint satisfaction problem is approached with a stochastic scheme that operates directly in the complex subspace where all constraints are observed. To navigate this subspace efficaciously, the actual lighting situation is taken into account. We demonstrate our system on multiple examples spanning a variety of architectural structures and lighting designs. Copyright held by the Owner/Author.

Clinical Processes - The Killer Application for Constraint-Based Process Interactions

DEFF Research Database (Denmark)

Jiménez-Ramírez, Andrés; Barba, Irene; Reichert, Manfred

2018-01-01

. The scenario is subject to complex temporal constraints and entails the need for coordinating the constraint-based interactions among the processes related to a patient treatment process. As demonstrated in this work, the selected real process scenario can be suitably modeled through a declarative approach....... examples. However, to the best of our knowledge, they have not been used to model complex, real-world scenarios that comprise constraints going beyond control-flow. In this paper, we propose the use of a declarative language for modeling a sophisticated healthcare process scenario from the real world......For more than a decade, the interest in aligning information systems in a process-oriented way has been increasing. To enable operational support for business processes, the latter are usually specified in an imperative way. The resulting process models, however, tend to be too rigid to meet...

A user friendly method for image based acquisition of constraint information during constrained motion of servo manipulator in hot-cells

International Nuclear Information System (INIS)

Saini, Surendra Singh; Sarkar, Ushnish; Swaroop, Tumapala Teja; Panjikkal, Sreejith; Ray, Debasish Datta

2016-01-01

In master slave manipulator, slave arm is controlled by an operator to manipulate the objects in remote environment using an iso-kinematic master arm which is located in the control room. In such a scenario, where the actual work environment is separated from the operator, formulation of techniques for assisting the operator to execute constrained motion (preferential inclusion or preferential exclusion of workspace zones) in the slave environment are not only helpful, but also essential. We had earlier demonstrated the efficacy of constraint motion with predefined geometrical constraints of various types. However, in a hot-cell scenario the generation of the constraint equations is difficult since we shall not have access to the cell for taking measurements. In this paper, a user friendly method is proposed for image based acquisition of the various constraint geometries thus eliminating the need to take in-cell measurements. For this purpose various hot cell tasks and required geometrical primitives pertaining to these tasks have been surveyed and an algorithm has been developed for generating the constraint geometry for each primitive. This methodology shall increase the efficiency and ease of use of the hot cell Telemanipulator by providing real time constraint acquisition and subsequent assistive force based constrained motion. (author)

Subsidiary divestiture and acquisition in a financial crisis: operational focus, financial constraints, and ownership

Czech Academy of Sciences Publication Activity Database

Zhou, Y. M.; Li, X.; Švejnar, Jan

2011-01-01

Roč. 17, č. 2 (2011), s. 272-287 ISSN 0929-1199 R&D Projects: GA ČR GAP402/10/2130; GA MŠk LC542 Institutional research plan: CEZ:MSM0021620846 Keywords : divestiture * corporate restructuring * financial constraints Subject RIV: AH - Economics Impact factor: 1.447, year: 2011

TRADING-OFF CONSTRAINTS IN THE PUMP SCHEDULING OPTIMIZATION OF WATER DISTRIBUTION NETWORKS

Directory of Open Access Journals (Sweden)

Gencer Genço\\u011Flu

2016-01-01

Full Text Available Pumps are one of the essential components of water supply systems. Depending of the topography, a water supply system may completely rely on pumping. They may consume non-negligible amount of water authorities' budgets during operation. Besides their energy costs, maintaining the healthiness of pumping systems is another concern for authorities. This study represents a multi-objective optimization method for pump scheduling problem. The optimization objective contains hydraulic and operational constraints. Switching of pumps and usage of electricity tariff are assumed to be key factors for operational reliability and energy consumption and costs of pumping systems. The local optimals for systems operational reliability, energy consumptions and energy costs are investigated resulting from trading-off pump switch and electricity tariff constraints within given set of boundary conditions. In the study, a custom made program is employed that combines genetic algorithm based optimization module with hydraulic network simulation software -EPANET. Developed method is applied on the case study network; N8-3 pressure zone of the Northern Supply of Ankara (Turkey Water Distribution Network. This work offers an efficient method for water authorities aiming to optimize pumping schedules considering expenditures and operational reliability mutually.

Management model of productive capacity: integrating theory of constraints and the global operational efficiency index (IROG

Directory of Open Access Journals (Sweden)

Diego Augusto Pacheco

2012-08-01

Full Text Available This paper presents a model of management capacity in productive systems integrating the concepts of the Theory of Constraints and Total Productive Maintenance (TPM. The main objective of this study is to discuss and propose a model of management capacity, able to answer the following key questions: i capacity indicators which should be considered and how to measure them to measure the productive capacity of manufacturing systems? ii what is the real productive capacity of the system analyzed under a determined relationship between capacity and demand? The discussion of the proposed model is relevant because the definition of productive capacity system enables better management of resources and capabilities, improve production scheduling on the factory floor and meeting the demands imposed by the market. This paper presents the proposition of using the Operating Income Index Global (IROG with a different approach from traditional literature dealing with the theme, presented by Nakajima (1988. The results of this paper enable to develop a model to determine the capacity of the production system and the impact on the productive capacity of the entire system, not to consider the quality conformances that occur after the bottleneck resource of the production flow.

Enforcement of entailment constraints in distributed service-based business processes.

Science.gov (United States)

Hummer, Waldemar; Gaubatz, Patrick; Strembeck, Mark; Zdun, Uwe; Dustdar, Schahram

2013-11-01

A distributed business process is executed in a distributed computing environment. The service-oriented architecture (SOA) paradigm is a popular option for the integration of software services and execution of distributed business processes. Entailment constraints, such as mutual exclusion and binding constraints, are important means to control process execution. Mutually exclusive tasks result from the division of powerful rights and responsibilities to prevent fraud and abuse. In contrast, binding constraints define that a subject who performed one task must also perform the corresponding bound task(s). We aim to provide a model-driven approach for the specification and enforcement of task-based entailment constraints in distributed service-based business processes. Based on a generic metamodel, we define a domain-specific language (DSL) that maps the different modeling-level artifacts to the implementation-level. The DSL integrates elements from role-based access control (RBAC) with the tasks that are performed in a business process. Process definitions are annotated using the DSL, and our software platform uses automated model transformations to produce executable WS-BPEL specifications which enforce the entailment constraints. We evaluate the impact of constraint enforcement on runtime performance for five selected service-based processes from existing literature. Our evaluation demonstrates that the approach correctly enforces task-based entailment constraints at runtime. The performance experiments illustrate that the runtime enforcement operates with an overhead that scales well up to the order of several ten thousand logged invocations. Using our DSL annotations, the user-defined process definition remains declarative and clean of security enforcement code. Our approach decouples the concerns of (non-technical) domain experts from technical details of entailment constraint enforcement. The developed framework integrates seamlessly with WS-BPEL and the Web

Effect Of Credit Constraint On Production Efficiency Of Farm ...

African Journals Online (AJOL)

Credit constraint in agriculture affects not only the purchasing power of producers to procure farm inputs and to cover operating costs in the short run, but also their capacity to make farm-related investments as well as risk behavior in technology choice and adoption. These, in turn, influence technical efficiencies of the ...

OPERATIONAL RESTRICTIONS FOR REDUCING NOISE AND THE SAFETY OF AIR OPERATIONS

Directory of Open Access Journals (Sweden)

Anna KWASIBORSKA

2017-03-01

Full Text Available Many European airports are located in close proximity to residential or protected areas. Aircraft noise emissions caused by the landing and taking off of aircraft are a big problem in these areas. From an operational point of view, the method for reducing noise is to reduce traffic volume or change its organization, especially during the night. Some procedures and tools have been developed to support air traffic management in the implementation of operational constraints necessary to maintain noise at an acceptable level. The objective of this paper is to analyse the effectiveness of these tools. For this purpose, we have analysed existing methods of operational noise reduction, taking into account their influence on the structure, smoothness, punctuality and, especially, the safety of air traffic. As a result, existing risks have been identified, while methods have been proposed to combine two important air traffic service tasks: ensuring safety, while taking into account the environmental constraints, especially in relation to the acoustic climate.

A Dynamic Non Energy Storing Guidance Constraint with Motion Redirection for Robot Assisted Surgery

Science.gov (United States)

2016-12-01

move during the operation. Robot -assisted beating heart surgery is an example of procedures that can benefit from dynamic constraints. Their...A Dynamic Non-Energy-Storing Guidance Constraint with Motion Redirection for Robot -Assisted Surgery Nima Enayati, Eva C. Alves Costa, Giancarlo...Momi, and G. Ferrigno, “Haptics in Robot -Assisted Surgery : Challenges and Benefits,” IEEE Rev. Biomed. Eng., 2016. [2] L. B. Rosenberg, “Virtual

Elementary Thermal Operations

DEFF Research Database (Denmark)

Lostaglio, Matteo; Alhambra, Álvaro M.; Perry, Christopher

2018-01-01

To what extent do thermodynamic resource theories capture physically relevant constraints? Inspired by quantum computation, we define a set of elementary thermodynamic gates that only act on 2 energy levels of a system at a time. We show that this theory is well reproduced by a Jaynes-Cummings in......To what extent do thermodynamic resource theories capture physically relevant constraints? Inspired by quantum computation, we define a set of elementary thermodynamic gates that only act on 2 energy levels of a system at a time. We show that this theory is well reproduced by a Jaynes......-Cummings interaction in rotating wave approximation and draw a connection to standard descriptions of thermalisation. We then prove that elementary thermal operations present tighter constraints on the allowed transformations than thermal operations. Mathematically, this illustrates the failure at finite temperature...... to do so, including necessary and sufficient conditions for a given change of the population to be possible. As an example, we describe the resource theory of the Jaynes-Cummings model. Finally, we initiate an investigation into how our resource theories can be applied to Heat Bath Algorithmic Cooling...

Crack-tip constraint analyses and constraint-dependent LBB curves for circumferential through-wall cracked pipes

Energy Technology Data Exchange (ETDEWEB)

Chen, Y.L.; Wang, G.Z., E-mail: gzwang@ecust.edu.cn; Xuan, F.Z.; Tu, S.T.

2015-04-15

Highlights: • Solution of constraint parameter τ* for through-wall cracked pipes has been obtained. • Constraint increases with increasing crack length and radius–thickness ratio of pipes. • Constraint-dependent LBB curve for through-wall cracked pipes has been constructed. • For increasing accuracy of LBB assessments, constraint effect should be considered. - Abstract: The leak-before-break (LBB) concept has been widely applied in the structural integrity assessments of pressured pipes in nuclear power plants. However, the crack-tip constraint effects in LBB analyses and designs cannot be incorporated. In this paper, by using three-dimensional finite element calculations, the modified load-independent T-stress constraint parameter τ* for circumferential through-wall cracked pipes with different geometries and crack sizes has been analyzed under different loading conditions, and the solutions of the crack-tip constraint parameter τ* have been obtained. Based on the τ* solutions and constraint-dependent J–R curves of a steel, the constraint-dependent LBB (leak-before-break) curves have been constructed. The results show that the constraint τ* increases with increasing crack length θ, mean radius R{sub m} and radius–thickness ratio R{sub m}/t of the pipes. In LBB analyses, the critical crack length calculated by the J–R curve of the standard high constraint specimen for pipes with shorter cracks is over-conservative, and the degree of conservatism increases with decreasing crack length θ, R{sub m} and R{sub m}/t. Therefore, the constraint-dependent LBB curves should be constructed to modify the over-conservatism and increase accuracy of LBB assessments.

Quantization of 2 + 1-spinning particles and bifermionic constraint problem

Energy Technology Data Exchange (ETDEWEB)

Fresneda, R.; Gavrilov, S.P.; Gitman, D.M.; Moshin, P.Yu. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica

2004-07-01

In this paper, we have quantized a P- and T-noninvariant pseudoclassical model of a massive relativistic spin-1=2 particle in 2 + 1 dimensions, on the background of an arbitrary U(1) gauge vector field. A peculiar feature of the model at the classical level is that it contains a bifermionic first-class constraint, which does not admit gauge-fixing. It is shown that this first-class constraint can be realized at the quantum level as a bounded operator, which is imposed as a condition on the state vectors (by analogy with the Dirac quantization method). This allows us to generalize the quantization scheme [?] in case there is a bifermionic first-class constraint.We present a detailed construction of the Hilbert space and verify that the constructed QM possesses the necessary symmetry properties. We show that the condition of preservation of the classical symmetries under the restricted Lorentz transformations and the U(1) transformations allows one to realize the operator algebra in an unambiguous way. Within the constructed relativistic QM, we select a physical subspace which describes the one-particle sector. The physical sector of the QM contains both particles and antiparticles with positive energy hat {omega} levels, and exactly reproduces the one-particle sector of the quantum theory of the 2 + 1 spinor field. (author)

Misconceptions and constraints

International Nuclear Information System (INIS)

Whitten, M.; Mahon, R.

2005-01-01

In theory, the sterile insect technique (SIT) is applicable to a wide variety of invertebrate pests. However, in practice, the approach has been successfully applied to only a few major pests. Chapters in this volume address possible reasons for this discrepancy, e.g. Klassen, Lance and McInnis, and Robinson and Hendrichs. The shortfall between theory and practice is partly due to the persistence of some common misconceptions, but it is mainly due to one constraint, or a combination of constraints, that are biological, financial, social or political in nature. This chapter's goal is to dispel some major misconceptions, and view the constraints as challenges to overcome, seeing them as opportunities to exploit. Some of the common misconceptions include: (1) released insects retain residual radiation, (2) females must be monogamous, (3) released males must be fully sterile, (4) eradication is the only goal, (5) the SIT is too sophisticated for developing countries, and (6) the SIT is not a component of an area-wide integrated pest management (AW-IPM) strategy. The more obvious constraints are the perceived high costs of the SIT, and the low competitiveness of released sterile males. The perceived high up-front costs of the SIT, their visibility, and the lack of private investment (compared with alternative suppression measures) emerge as serious constraints. Failure to appreciate the true nature of genetic approaches, such as the SIT, may pose a significant constraint to the wider adoption of the SIT and other genetically-based tactics, e.g. transgenic genetically modified organisms (GMOs). Lack of support for the necessary underpinning strategic research also appears to be an important constraint. Hence the case for extensive strategic research in ecology, population dynamics, genetics, and insect behaviour and nutrition is a compelling one. Raising the competitiveness of released sterile males remains the major research objective of the SIT. (author)

Weak solutions for nonlocal evolution variational inequalities involving gradient constraints and variable exponent

Directory of Open Access Journals (Sweden)

Mingqi Xiang

2013-04-01

Full Text Available In this article, we study a class of nonlocal quasilinear parabolic variational inequality involving $p(x$-Laplacian operator and gradient constraint on a bounded domain. Choosing a special penalty functional according to the gradient constraint, we transform the variational inequality to a parabolic equation. By means of Galerkin's approximation method, we obtain the existence of weak solutions for this equation, and then through a priori estimates, we obtain the weak solutions of variational inequality.

Architecture for spacecraft operations planning

Science.gov (United States)

Davis, William S.

1991-01-01

A system which generates plans for the dynamic environment of space operations is discussed. This system synthesizes plans by combining known operations under a set of physical, functional, and temperal constraints from various plan entities, which are modeled independently but combine in a flexible manner to suit dynamic planning needs. This independence allows the generation of a single plan source which can be compiled and applied to a variety of agents. The architecture blends elements of temperal logic, nonlinear planning, and object oriented constraint modeling to achieve its flexibility. This system was applied to the domain of the Intravehicular Activity (IVA) maintenance and repair aboard Space Station Freedom testbed.

Wind turbine control with constraint handling: a model predictive control approach

DEFF Research Database (Denmark)

Henriksen, Lars Christian; Hansen, Morten Hartvig; Poulsen, Niels Kjølstad

2012-01-01

on model predictive control, a control method well suited for constraint handling. The performance of the presented controller during an extreme operating gust is compared to that of a proportional-integral controller with integrator anti-windup. Furthermore, the presented controller-s capability...

An effective heuristic for combined heat-and-power production planning with power ramp constraints

International Nuclear Information System (INIS)

Rong, Aiying; Lahdelma, Risto

2007-01-01

Combined heat-and-power (CHP) production is an increasingly important technology for its efficient utilization of primary-energy resources and for reducing CO 2 emissions. In the CHP plant, the generation of heat-and-power follows a joint characteristic, which makes the determination of both the marginal power production cost (MPPC) and the feasible operating region for the plant more complicated than for the power-only generation plant. Due to the interdependence between heat and power production, the power-ramp constraints, which limit how much the power production of a CHP plant may increase or decrease between two successive periods, may also imply constraints on the heat production. In this paper, we investigate the impact of power-ramp constraints on CHP production planning and develop a robust heuristic for dealing with the power-ramp constraints based on the solution to the problem with relaxed ramp-constraints (RRC). Numerical results based on realistic production models show that the heuristic can generate high-quality solutions efficiently. (author)

Modeling Network Transition Constraints with Hypergraphs

DEFF Research Database (Denmark)

Harrod, Steven

2011-01-01

Discrete time dynamic graphs are frequently used to model multicommodity flows or activity paths through constrained resources, but simple graphs fail to capture the interaction effects of resource transitions. The resulting schedules are not operationally feasible, and return inflated objective...... values. A directed hypergraph formulation is derived to address railway network sequencing constraints, and an experimental problem sample solved to estimate the magnitude of objective inflation when interaction effects are ignored. The model is used to demonstrate the value of advance scheduling...... of train paths on a busy North American railway....

Constraints and Creativity in NPD - Testing the Impact of 'Late Constraints'

DEFF Research Database (Denmark)

Onarheim, Balder; Valgeirsdóttir, Dagný

experiment was conducted, involving 12 teams of industrial designers from three different countries, each team working on two 30 minutes design tasks. In one condition all constraints were given at the start, and in the other one new radical constraint was added after 12 minutes. The output from all 24 tasks......The aim of the presented work is to investigate how the timing of project constraints can influence the creativity of the output in New Product Development (NPD) projects. When seeking to produce a creative output, is it beneficial to know all constraints when initiating a project...... was assessed for creativity using the Consensual Assessment Technique (CAT), and a comparative within-subjects analysis found no significant different between the two conditions. Controlling for task and assessor a small but non-significant effect was found, in favor of the ‘late constraint’ condition. Thus...

Prospects for nuclear terrorism: psychological motivations and constraints

International Nuclear Information System (INIS)

Post, J.M.

1987-01-01

In considering the implications of psychological understandings to the specific case of nuclear terrorism, it is emphasized that distorted decision making does not equate to totally irrational decision making. In certain circumstances, however, the distorted individual and group decision-making psychology could influence the group toward a high-risk option such as nuclear terrorism. For terrorists operating within their own national boundaries, a terrorist act producing mass casualties would generally be counterproductive. For groups acting across national boundaries, however, this constraint does not apply to nearly the same degree. Although the opprobrium of the West will be a constraint for some, it will not be equally so for all terrorist groups. The degree of disincentive will relate in particular to the major audience of influence. Also, there are the terrorist losers who are being shunted aside and losing the recognition they seek. Such a group could justify a terrorist spectacular in order to regain influence on the basis of a what have we got to lose rationale. In thinking about the possibility of nuclear terrorism, it is important to distinguish between the actual detonation of a device and the use of a device for extortion and influence. The constraints against the latter are significantly reduced in contrast to acts producing mass casualties. The constraints are even more reduced in the case of the plausible nuclear hoax, an option that can be expected to become more frequent

Tail Risk Constraints and Maximum Entropy

Directory of Open Access Journals (Sweden)

Donald Geman

2015-06-01

Full Text Available Portfolio selection in the financial literature has essentially been analyzed under two central assumptions: full knowledge of the joint probability distribution of the returns of the securities that will comprise the target portfolio; and investors’ preferences are expressed through a utility function. In the real world, operators build portfolios under risk constraints which are expressed both by their clients and regulators and which bear on the maximal loss that may be generated over a given time period at a given confidence level (the so-called Value at Risk of the position. Interestingly, in the finance literature, a serious discussion of how much or little is known from a probabilistic standpoint about the multi-dimensional density of the assets’ returns seems to be of limited relevance. Our approach in contrast is to highlight these issues and then adopt throughout a framework of entropy maximization to represent the real world ignorance of the “true” probability distributions, both univariate and multivariate, of traded securities’ returns. In this setting, we identify the optimal portfolio under a number of downside risk constraints. Two interesting results are exhibited: (i the left- tail constraints are sufficiently powerful to override all other considerations in the conventional theory; (ii the “barbell portfolio” (maximal certainty/ low risk in one set of holdings, maximal uncertainty in another, which is quite familiar to traders, naturally emerges in our construction.

Remote tool development for nuclear dismantling operations

International Nuclear Information System (INIS)

Craig, G.; Ferlay, J.C.; Ieracitano, F.

2003-01-01

Remote tool systems to undertake nuclear dismantling operations require careful design and development not only to perform their given duty but to perform it safely within the constraints imposed by harsh environmental conditions. Framatome ANP NUCLEAR SERVICES has for a long time developed and qualified equipment to undertake specific maintenance operations of nuclear reactors. The tool development methodology from this activity has since been adapted to resolve some very challenging reactor dismantling operations which are demonstrated in this paper. Each nuclear decommissioning project is a unique case, technical characterisation data is generally incomplete. The development of the dismantling methodology and associated equipment is by and large an iterative process combining design and simulation with feasibility and validation testing. The first stage of the development process involves feasibility testing of industrial tools and examining adaptations necessary to control and deploy the tool remotely with respect to the chosen methodology and environmental constraints. This results in a prototype tool and deployment system to validate the basic process. The second stage involves detailed design which integrates any remaining technical and environmental constraints. At the end of this stage, tools and deployment systems, operators and operating procedures are qualified on full scale mock ups. (authors)

Effect of plastic prestrain on the crack tip constraint of pipeline steels

International Nuclear Information System (INIS)

Eikrem, P.A.; Zhang, Z.L.; Nyhus, B.

2007-01-01

Before and during operation, pipelines may suffer from plastic pre-deformation due to accidental loading, cold bending and ground movement. Plastic prestrain not only modifies steel's yield and flow properties but also influences its fracture performance. This paper focuses on the effect of prestrain history on crack driving force and crack tip constraint. A single-edge notched tension specimen has been selected for the study and the crack is assumed to exist before a prestrain history was applied. The results show that prestrain history has a strong effect on the crack tip stress field. A new parameter has been proposed to characterize the prestrain-induced crack tip constraint. For the same crack tip opening displacement level, prestrain history will elevate the crack tip stress field. The prestrain-induced constraint decreases with the increase of loading

Interactive orbital proximity operations planning system instruction and training guide

Science.gov (United States)

Grunwald, Arthur J.; Ellis, Stephen R.

1994-01-01

This guide instructs users in the operation of a Proximity Operations Planning System. This system uses an interactive graphical method for planning fuel-efficient rendezvous trajectories in the multi-spacecraft environment of the space station and allows the operator to compose a multi-burn transfer trajectory between orbit initial chaser and target trajectories. The available task time (window) of the mission is predetermined and the maneuver is subject to various operational constraints, such as departure, arrival, spatial, plume impingement, and en route passage constraints. The maneuvers are described in terms of the relative motion experienced in a space station centered coordinate system. Both in-orbital plane as well as out-of-orbital plane maneuvering is considered. A number of visual optimization aids are used for assisting the operator in reaching fuel-efficient solutions. These optimization aids are based on the Primer Vector theory. The visual feedback of trajectory shapes, operational constraints, and optimization functions, provided by user-transparent and continuously active background computations, allows the operator to make fast, iterative design changes that rapidly converge to fuel-efficient solutions. The planning tool is an example of operator-assisted optimization of nonlinear cost functions.

THE GOAL AND THE GOLD MINE: Constraints Management and the Dutch Herring Fishing Industry, 1400-1700

Directory of Open Access Journals (Sweden)

Michael Scott Martin

2009-01-01

Full Text Available In many ways, the Netherlands set the pace for European economic growth in the fifteenth through the eighteenth centuries. The Dutch herring fishing industry was critical to this modern economic progress. A comparative study of this enterprise to the lean manufacturing tool of constraints management provides insight into how the Dutch dominated this lucrative industry. Improvements by Dutch fishing interests in technology, practice, procedures and quality control were consistent with the constraints management model. English and Scottish competitors failed to identify these constraints and thus, failed to challenge Dutch operators. The Dutch fishing industry practiced and understood constraints management and used it to monopolize the export herring market for three centuries.

Energy Constraints for Building Large-Scale Systems

Science.gov (United States)

2016-03-17

although most systems built to date do not consider these issues as primary constraints. Keywords: Neuromorphic Engineering; Cortical Operation...2Mbyte, 32bit input data, and 1Mbyte, 32bit output data, results in 3.1mW (Vdd = 2.5V) of power, even though one might find a DSP chip computing at...4MMAC(/s)/mW power efficiency [5], close to the power / energy efficiency wall [6]. A memory chip or data source further away requires even higher

The Frame Constraint on Experimentally Elicited Speech Errors in Japanese

Science.gov (United States)

Saito, Akie; Inoue, Tomoyoshi

2017-01-01

The so-called syllable position effect in speech errors has been interpreted as reflecting constraints posed by the frame structure of a given language, which is separately operating from linguistic content during speech production. The effect refers to the phenomenon that when a speech error occurs, replaced and replacing sounds tend to be in the…

Financing Constraints and Entrepreneurship

OpenAIRE

William R. Kerr; Ramana Nanda

2009-01-01

Financing constraints are one of the biggest concerns impacting potential entrepreneurs around the world. Given the important role that entrepreneurship is believed to play in the process of economic growth, alleviating financing constraints for would-be entrepreneurs is also an important goal for policymakers worldwide. We review two major streams of research examining the relevance of financing constraints for entrepreneurship. We then introduce a framework that provides a unified perspecti...

An alternative approach in operator allocation labor intensive manufacturing system: A three-phase methodology framework

Science.gov (United States)

Mat Rani, Ruzanita; Ismail, Wan Rosmanira

2013-04-01

Operator allocation is one of the most important decisions that can affect productivity in labor-intensive manufacturing system. Improper decision on operator allocation will reduce company's throughput and increase waste. Therefore, all factors such as operators' performance and operational constraints need to be considered in making the best operator allocation decision. Most of previous studies used two phases methodology. In two phases methodology, they used operational constraints and treated all operators to have the same level of performance for making decision on operator allocation. Therefore, in this paper a three-phase methodology is proposed to determine the optimal operator allocation. This methodology advances the existing approach on operator allocation by combining operators' performance and operational constraints. The methodology starts with evaluating the operators' performance. Then, it is followed with determining inputs and outputs for operator allocation alternatives and it ends with determining the optimal operator allocation. This paper will give ideas and directions to the management of the manufacturing company in determining the optimal operator allocation decision.

Creativity from Constraints in Engineering Design

DEFF Research Database (Denmark)

Onarheim, Balder

2012-01-01

This paper investigates the role of constraints in limiting and enhancing creativity in engineering design. Based on a review of literature relating constraints to creativity, the paper presents a longitudinal participatory study from Coloplast A/S, a major international producer of disposable...... and ownership of formal constraints played a crucial role in defining their influence on creativity – along with the tacit constraints held by the designers. The designers were found to be highly constraint focused, and four main creative strategies for constraint manipulation were observed: blackboxing...

Introducing radiality constraints in capacitated location-routing problems

Directory of Open Access Journals (Sweden)

Eliana Mirledy Toro Ocampo

2017-03-01

Full Text Available In this paper, we introduce a unified mathematical formulation for the Capacitated Vehicle Routing Problem (CVRP and for the Capacitated Location Routing Problem (CLRP, adopting radiality constraints in order to guarantee valid routes and eliminate subtours. This idea is inspired by formulations already employed in electric power distribution networks, which requires a radial topology in its operation. The results show that the proposed formulation greatly improves the convergence of the solver.

Deepening Contractions and Collateral Constraints

DEFF Research Database (Denmark)

Jensen, Henrik; Ravn, Søren Hove; Santoro, Emiliano

and occasionally non-binding credit constraints. Easier credit access increases the likelihood that constraints become slack in the face of expansionary shocks, while contractionary shocks are further amplified due to tighter constraints. As a result, busts gradually become deeper than booms. Based...

The position of a standard optical computer mouse affects cardiorespiratory responses during the operation of a computer under time constraints.

Science.gov (United States)

Sako, Shunji; Sugiura, Hiromichi; Tanoue, Hironori; Kojima, Makoto; Kono, Mitsunobu; Inaba, Ryoichi

2014-08-01

This study investigated the association between task-induced stress and fatigue by examining the cardiovascular responses of subjects using different mouse positions while operating a computer under time constraints. The study was participated by 16 young, healthy men and examined the use of optical mouse devices affixed to laptop computers. Two mouse positions were investigated: (1) the distal position (DP), in which the subjects place their forearms on the desk accompanied by the abduction and flexion of their shoulder joints, and (2) the proximal position (PP), in which the subjects place only their wrists on the desk without using an armrest. The subjects continued each task for 16 min. We assessed differences in several characteristics according to mouse position, including expired gas values, autonomic nerve activities (based on cardiorespiratory responses), operating efficiencies (based on word counts), and fatigue levels (based on the visual analog scale - VAS). Oxygen consumption (VO(2)), the ratio of inspiration time to respiration time (T(i)/T(total)), respiratory rate (RR), minute ventilation (VE), and the ratio of expiration to inspiration (Te/T(i)) were significantly lower when the participants were performing the task in the DP than those obtained in the PP. Tidal volume (VT), carbon dioxide output rates (VCO(2)/VE), and oxygen extraction fractions (VO(2)/VE) were significantly higher for the DP than they were for the PP. No significant difference in VAS was observed between the positions; however, as the task progressed, autonomic nerve activities were lower and operating efficiencies were significantly higher for the DP than they were for the PP. Our results suggest that the DP has fewer effects on cardiorespiratory functions, causes lower levels of sympathetic nerve activity and mental stress, and produces a higher total workload than the PP. This suggests that the DP is preferable to the PP when operating a computer.

The AECL operator companion

International Nuclear Information System (INIS)

Lupton, L.R.; Anderson, L.L.; Basso, R.A.J.

1989-11-01

As CANDU plants become more complex, and are operated under tighter constraints and for longer periods between outages, plant operations staff will have to absorb more information to correctly and rapidly respond to upsets. A development program is underway at AECL to use expert systems and interactive media tools to assist operations staff of existing and future CANDU plants. The complete system for plant information access and display, on-line advice and diagnosis, and interactive operating procedures is called the Operator Companion. A prototype, consisting of operator consoles, expert systems and simulation modules in a distributed architecture, is currently being developed to demonstrate the concepts of the Operator Companion

A mixed integer programming model for a continuous move transportation problem with service constraints

Directory of Open Access Journals (Sweden)

J. Fabian Lopez

2010-01-01

Full Text Available We consider a Pickup and Delivery Vehicle Routing Problem (PDP commonly encountered in real-world logistics operations. The problem involves a set of practical complications that have received little attention in the vehicle routing literature. In this problem, there are multiple vehicle types available to cover a set of pickup and delivery requests, each of which has pickup time windows and delivery time windows. Transportation orders and vehicle types must satisfy a set of compatibility constraints that specify which orders cannot be covered by which vehicle types. In addition we include some dock service capacity constraints as is required on common real world operations. This problem requires to be attended on large scale instances (orders ≥ 500, (vehicles ≥ 150. As a generalization of the traveling salesman problem, clearly this problem is NP-hard. The exact algorithms are too slow for large scale instances. The PDP-TWDS is both a packing problem (assign order to vehicles, and a routing problem (find the best route for each vehicle. We propose to solve the problem in three stages. The first stage constructs initials solutions at aggregate level relaxing some constraints on the original problem. The other two stages imposes time windows and dock service constraints. Our results are favorable finding good quality solutions in relatively short computational times.

Constraint and Flight Rule Management for Space Mission Operations

Science.gov (United States)

Barreiro, J.; Chachere, J.; Frank, J.; Bertels, C.; Crocker, A.

2010-01-01

The exploration of space is one of the most fascinating domains to study from a human factors perspective. Like other complex work domains such as aviation (Pritchett and Kim, 2008), air traffic management (Durso and Manning, 2008), health care (Morrow, North, and Wickens, 2006), homeland security (Cooke and Winner, 2008), and vehicle control (Lee, 2006), space exploration is a large-scale sociotechnical work domain characterized by complexity, dynamism, uncertainty, and risk in real-time operational contexts (Perrow, 1999; Woods et al, 1994). Nearly the entire gamut of human factors issues - for example, human-automation interaction (Sheridan and Parasuraman, 2006), telerobotics, display and control design (Smith, Bennett, and Stone, 2006), usability, anthropometry (Chaffin, 2008), biomechanics (Marras and Radwin, 2006), safety engineering, emergency operations, maintenance human factors, situation awareness (Tenney and Pew, 2006), crew resource management (Salas et al., 2006), methods for cognitive work analysis (Bisantz and Roth, 2008) and the like -- are applicable to astronauts, mission control, operational medicine, Space Shuttle manufacturing and assembly operations, and space suit designers as they are in other work domains (e.g., Bloomberg, 2003; Bos et al, 2006; Brooks and Ince, 1992; Casler and Cook, 1999; Jones, 1994; McCurdy et al, 2006; Neerincx et aI., 2006; Olofinboba and Dorneich, 2005; Patterson, Watts-Perotti and Woods, 1999; Patterson and Woods, 2001; Seagull et ai, 2007; Sierhuis, Clancey and Sims, 2002). The human exploration of space also has unique challenges of particular interest to human factors research and practice. This chapter provides an overview of those issues and reports on some of the latest research results as well as the latest challenges still facing the field.

Loss-Averse Inventory and Borrowing Decisions with Constraints on Working Capital in Fashion and Textiles Industry

Directory of Open Access Journals (Sweden)

Lijun Ma

2013-01-01

Full Text Available Traditional inventory models focus on operational decisions and inventory control. Quite few models consider the financial constraint and decision bias such as loss aversion, which are the reality in today's business environment, especially for the fashion and textiles industry. In this paper we study the inventory control problem for a loss-averse retailer with financial constraint for operations in a periodic review setting in a finite horizon. We characterize the optimal inventory control policies with self-financing or with borrowing as capital-dependent base-stock policies. We demonstrate with numerical examples that the optimal base-stock level is nonincreasing in the accumulated wealth and the loss-aversion indicator.

Occupational dose constraint

International Nuclear Information System (INIS)

Heilbron Filho, Paulo Fernando Lavalle; Xavier, Ana Maria

2005-01-01

The revision process of the international radiological protection regulations has resulted in the adoption of new concepts, such as practice, intervention, avoidable and restriction of dose (dose constraint). The latter deserving of special mention since it may involve reducing a priori of the dose limits established both for the public and to individuals occupationally exposed, values that can be further reduced, depending on the application of the principle of optimization. This article aims to present, with clarity, from the criteria adopted to define dose constraint values to the public, a methodology to establish the dose constraint values for occupationally exposed individuals, as well as an example of the application of this methodology to the practice of industrial radiography

Uncertainty management by relaxation of conflicting constraints in production process scheduling

Science.gov (United States)

Dorn, Juergen; Slany, Wolfgang; Stary, Christian

1992-01-01

Mathematical-analytical methods as used in Operations Research approaches are often insufficient for scheduling problems. This is due to three reasons: the combinatorial complexity of the search space, conflicting objectives for production optimization, and the uncertainty in the production process. Knowledge-based techniques, especially approximate reasoning and constraint relaxation, are promising ways to overcome these problems. A case study from an industrial CIM environment, namely high-grade steel production, is presented to demonstrate how knowledge-based scheduling with the desired capabilities could work. By using fuzzy set theory, the applied knowledge representation technique covers the uncertainty inherent in the problem domain. Based on this knowledge representation, a classification of jobs according to their importance is defined which is then used for the straightforward generation of a schedule. A control strategy which comprises organizational, spatial, temporal, and chemical constraints is introduced. The strategy supports the dynamic relaxation of conflicting constraints in order to improve tentative schedules.

Modeling and Design of Container Terminal Operations

NARCIS (Netherlands)

D. Roy (Debjit); M.B.M. de Koster (René)

2014-01-01

textabstractDesign of container terminal operations is complex because multiple factors affect the operational perfor- mance. These factors include: topological constraints, a large number of design parameters and settings, and stochastic interactions that interplay among the quayside, vehicle

Electric dipole moment constraints on minimal electroweak baryogenesis

CERN Document Server

Huber, S J; Ritz, A; Huber, Stephan J.; Pospelov, Maxim; Ritz, Adam

2007-01-01

We study the simplest generic extension of the Standard Model which allows for conventional electroweak baryogenesis, through the addition of dimension six operators in the Higgs sector. At least one such operator is required to be CP-odd, and we study the constraints on such a minimal setup, and related scenarios with minimal flavor violation, from the null results of searches for electric dipole moments (EDMs), utilizing the full set of two-loop contributions to the EDMs. The results indicate that the current bounds are stringent, particularly that of the recently updated neutron EDM, but fall short of ruling out these scenarios. The next generation of EDM experiments should be sufficiently sensitive to provide a conclusive test.

Solar constraints

International Nuclear Information System (INIS)

Provost, J.

1984-01-01

Accurate tests of the theory of stellar structure and evolution are available from the Sun's observations. The solar constraints are reviewed, with a special attention to the recent progress in observing global solar oscillations. Each constraint is sensitive to a given region of the Sun. The present solar models (standard, low Z, mixed) are discussed with respect to neutrino flux, low and high degree five-minute oscillations and low degree internal gravity modes. It appears that actually there do not exist solar models able to fully account for all the observed quantities. (Auth.)

Fermionic effective operators and Higgs production at a linear collider

International Nuclear Information System (INIS)

Kile, Jennifer; Ramsey-Musolf, Michael J.

2007-01-01

We study the possible contributions of dimension six operators containing fermion fields to Higgs production at a 500 GeV or 1 TeV e + e - linear collider. We show that--depending on the production mechanism--the effects of such operators can be kinematically enhanced relative to standard model (SM) contributions. We determine constraints on the operator coefficients implied by existing precision electroweak measurements and the scale of neutrino mass. We find that even in the presence of such constraints, substantial deviations from SM Higgs production cross sections are possible. We compare the effects of fermionic operators with those associated with purely bosonic operators that have been previously discussed in the literature

Temporal Concurrent Constraint Programming

DEFF Research Database (Denmark)

Nielsen, Mogens; Valencia Posso, Frank Dan

2002-01-01

The ntcc calculus is a model of non-deterministic temporal concurrent constraint programming. In this paper we study behavioral notions for this calculus. In the underlying computational model, concurrent constraint processes are executed in discrete time intervals. The behavioral notions studied...... reflect the reactive interactions between concurrent constraint processes and their environment, as well as internal interactions between individual processes. Relationships between the suggested notions are studied, and they are all proved to be decidable for a substantial fragment of the calculus...

Steam generator materials constraints in UK design gas-cooled reactors

International Nuclear Information System (INIS)

James, D.W.

1988-01-01

A widely reported problem with Magnox-type reactors was the oxidation of carbon steel components in gas circuits and steam generators. The effects of temperature, pressure, gas composition and steel composition on oxidation kinetics have been determined, thus allowing the probabilities of failure of critical components to be predicted for a given set of operating conditions. This risk analysis, coupled with regular inspection of reactor and boiler internals, has allowed continued operation of all U.K. Magnox plant. The Advanced Gas Cooled Reactor (AGR) is a direct development of the Magnox design. The first four AGRs commenced operation in 1976, at Hinkley Point 'B' and at Hunterston 'B'. All known materials problems with the steam generators have been diagnosed and solved by the development of appropriate operational strategies, together with minor plant modifications. Materials constraints no longer impose any restrictions to full load performance from the steam generators throughout the predicted life of the plant. Problems discussed in detail are: 1. oxidation of the 9 Cr - 1 Mo superheater. 2. Stress corrosion of the austenitic superheater. 3. Creep of the transition joints between the 9 Cr - 1 Mo and austenitic sections. With the 9 Cr - 1 Mo oxidation maximum temperature restriction virtually removed and creep constraints properly quantified, boiler operation in now favourably placed. Stress corrosion research has allowed the risk of tube failure to be related to time, temperature, stress and chemistry. As a result, the rigorous 'no wetting' policy has been relaxed for the normally high quality AGR feedwater, and the superheat margin has been reduced to 23 deg. C. This has increased the size of the operating window and reduced the number of expensive, and potentially harmful, plant trips. (author)

Theory of Constraints (TOC)

DEFF Research Database (Denmark)

Michelsen, Aage U.

2004-01-01

Tankegangen bag Theory of Constraints samt planlægningsprincippet Drum-Buffer-Rope. Endvidere skitse af The Thinking Process.......Tankegangen bag Theory of Constraints samt planlægningsprincippet Drum-Buffer-Rope. Endvidere skitse af The Thinking Process....

Consistent constraints on the Standard Model Effective Field Theory

International Nuclear Information System (INIS)

Berthier, Laure; Trott, Michael

2016-01-01

We develop the global constraint picture in the (linear) effective field theory generalisation of the Standard Model, incorporating data from detectors that operated at PEP, PETRA, TRISTAN, SpS, Tevatron, SLAC, LEPI and LEP II, as well as low energy precision data. We fit one hundred and three observables. We develop a theory error metric for this effective field theory, which is required when constraints on parameters at leading order in the power counting are to be pushed to the percent level, or beyond, unless the cut off scale is assumed to be large, Λ≳ 3 TeV. We more consistently incorporate theoretical errors in this work, avoiding this assumption, and as a direct consequence bounds on some leading parameters are relaxed. We show how an S,T analysis is modified by the theory errors we include as an illustrative example.

Sampling Operations on Big Data

Science.gov (United States)

2015-11-29

gories. These include edge sampling methods where edges are selected by a predetermined criteria; snowball sampling methods where algorithms start... Sampling Operations on Big Data Vijay Gadepally, Taylor Herr, Luke Johnson, Lauren Milechin, Maja Milosavljevic, Benjamin A. Miller Lincoln...process and disseminate information for discovery and exploration under real-time constraints. Common signal processing operations such as sampling and

Comparison of a constraint directed search to a genetic algorithm in a scheduling application

International Nuclear Information System (INIS)

Abbott, L.

1993-01-01

Scheduling plutonium containers for blending is a time-intensive operation. Several constraints must be taken into account; including the number of containers in a dissolver run, the size of each dissolver run, and the size and target purity of the blended mixture formed from these runs. Two types of algorithms have been used to solve this problem: a constraint directed search and a genetic algorithm. This paper discusses the implementation of these two different approaches to the problem and the strengths and weaknesses of each algorithm

Constraints to private sector operation: maintenance of municipal infrastructure

CSIR Research Space (South Africa)

Wall, K

2012-08-01

Full Text Available This paper discusses the potential of the private sector to take medium- or longterm responsibility for the operation and/or maintenance of elements of infrastructure owned by municipalities....

Selection of new constraints

International Nuclear Information System (INIS)

Sugier, A.

2003-01-01

The selected new constraints should be consistent with the scale of concern i.e. be expressed roughly as fractions or multiples of the average annual background. They should take into account risk considerations and include the values of the currents limits, constraints and other action levels. The recommendation is to select four leading values for the new constraints: 500 mSv ( single event or in a decade) as a maximum value, 0.01 mSv/year as a minimum value; and two intermediate values: 20 mSv/year and 0.3 mSv/year. This new set of dose constraints, representing basic minimum standards of protection for the individuals taking into account the specificity of the exposure situations are thus coherent with the current values which can be found in ICRP Publications. A few warning need however to be noticed: There is no more multi sources limit set by ICRP. The coherence between the proposed value of dose constraint (20 mSv/year) and the current occupational dose limit of 20 mSv/year is valid only if the workers are exposed to one single source. When there is more than one source, it will be necessary to apportion. The value of 1000 mSv lifetimes used for relocation can be expressed into annual dose, which gives approximately 10 mSv/year and is coherent with the proposed dose constraint. (N.C.)

Comparison of operation optimization methods in energy system modelling

DEFF Research Database (Denmark)

Ommen, Torben Schmidt; Markussen, Wiebke Brix; Elmegaard, Brian

2013-01-01

In areas with large shares of Combined Heat and Power (CHP) production, significant introduction of intermittent renewable power production may lead to an increased number of operational constraints. As the operation pattern of each utility plant is determined by optimization of economics......, possibilities for decoupling production constraints may be valuable. Introduction of heat pumps in the district heating network may pose this ability. In order to evaluate if the introduction of heat pumps is economically viable, we develop calculation methods for the operation patterns of each of the used...... energy technologies. In the paper, three frequently used operation optimization methods are examined with respect to their impact on operation management of the combined technologies. One of the investigated approaches utilises linear programming for optimisation, one uses linear programming with binary...

Minimal Flavor Constraints for Technicolor

DEFF Research Database (Denmark)

Sakuma, Hidenori; Sannino, Francesco

2010-01-01

We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self-coupling and mas......We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self...

Temporal Concurrent Constraint Programming

DEFF Research Database (Denmark)

Nielsen, Mogens; Palamidessi, Catuscia; Valencia, Frank Dan

2002-01-01

The ntcc calculus is a model of non-deterministic temporal concurrent constraint programming. In this paper we study behavioral notions for this calculus. In the underlying computational model, concurrent constraint processes are executed in discrete time intervals. The behavioral notions studied...

A multi-period, multi-regional generation expansion planning model incorporating unit commitment constraints

International Nuclear Information System (INIS)

Koltsaklis, Nikolaos E.; Georgiadis, Michael C.

2015-01-01

Highlights: • A short-term structured investment planning model has been developed. • Unit commitment problem is incorporated into the long-term planning horizon. • Inherent intermittency of renewables is modelled in a comprehensive way. • The impact of CO_2 emission pricing in long-term investment decisions is quantified. • The evolution of system’s marginal price is evaluated for all the planning horizon. - Abstract: This work presents a generic mixed integer linear programming (MILP) model that integrates the unit commitment problem (UCP), i.e., daily energy planning with the long-term generation expansion planning (GEP) framework. Typical daily constraints at an hourly level such as start-up and shut-down related decisions (start-up type, minimum up and down time, synchronization, soak and desynchronization time constraints), ramping limits, system reserve requirements are combined with representative yearly constraints such as power capacity additions, power generation bounds of each unit, peak reserve requirements, and energy policy issues (renewables penetration limits, CO_2 emissions cap and pricing). For modelling purposes, a representative day (24 h) of each month over a number of years has been employed in order to determine the optimal capacity additions, electricity market clearing prices, and daily operational planning of the studied power system. The model has been tested on an illustrative case study of the Greek power system. Our approach aims to provide useful insight into strategic and challenging decisions to be determined by investors and/or policy makers at a national and/or regional level by providing the optimal energy roadmap under real operating and design constraints.

Automated Derivation of Complex System Constraints from User Requirements

Science.gov (United States)

Foshee, Mark; Murey, Kim; Marsh, Angela

2010-01-01

The Payload Operations Integration Center (POIC) located at the Marshall Space Flight Center has the responsibility of integrating US payload science requirements for the International Space Station (ISS). All payload operations must request ISS system resources so that the resource usage will be included in the ISS on-board execution timelines. The scheduling of resources and building of the timeline is performed using the Consolidated Planning System (CPS). The ISS resources are quite complex due to the large number of components that must be accounted for. The planners at the POIC simplify the process for Payload Developers (PD) by providing the PDs with a application that has the basic functionality PDs need as well as list of simplified resources in the User Requirements Collection (URC) application. The planners maintained a mapping of the URC resources to the CPS resources. The process of manually converting PD's science requirements from a simplified representation to a more complex CPS representation is a time-consuming and tedious process. The goal is to provide a software solution to allow the planners to build a mapping of the complex CPS constraints to the basic URC constraints and automatically convert the PD's requirements into systems requirements during export to CPS.

Two-agent scheduling in open shops subject to machine availability and eligibility constraints

Directory of Open Access Journals (Sweden)

Ling-Huey Su

2015-09-01

Full Text Available Purpose: The aims of this article are to develop a new mathematical formulation and a new heuristic for the problem of preemptive two-agent scheduling in open shops subject to machine maintenance and eligibility constraints. Design/methodology: Using the ideas of minimum cost flow network and constraint programming, a heuristic and a network based linear programming are proposed to solve the problem. Findings: Computational experiments show that the heuristic generates a good quality schedule with a deviation of 0.25% on average from the optimum and the network based linear programming model can solve problems up to 110 jobs combined with 10 machines without considering the constraint that each operation can be processed on at most one machine at a time. In order to satisfy this constraint, a time consuming Constraint Programming is proposed. For n = 80 and m = 10, the average execution time for the combined models (linear programming model combined with Constraint programming exceeds two hours. Therefore, the heuristic algorithm we developed is very efficient and is in need. Practical implications: Its practical implication occurs in TFT-LCD and E-paper manufacturing wherein units go through a series of diagnostic tests that do not have to be performed in any specified order. Originality/value: The main contribution of the article is to split the time horizon into many time intervals and use the dispatching rule for each time interval in the heuristic algorithm, and also to combine the minimum cost flow network with the Constraint Programming to solve the problem optimally. 

Real-Time Optimization of a maturing North Sea gas asset with production constraints

NARCIS (Netherlands)

Linden, R.J.P. van der; Busking, T.E.

2013-01-01

As gas and oil fields mature their operation becomes increasingly more complex, due to complex process dynamics, like slugging, gas coning, water breakthrough, salt or hydrate deposition. Moreover these phenomena also lead to production constraints in the upstream facilities. This complexity asks

The roles of constraint-based and dedication-based influences on user's continued online shopping behavior.

Science.gov (United States)

Chang, Su-Chao; Chou, Chi-Min

2012-11-01

The objective of this study was to determine empirically the role of constraint-based and dedication-based influences as drivers of the intention to continue using online shopping websites. Constraint-based influences consist of two variables: trust and perceived switching costs. Dedication-based influences consist of three variables: satisfaction, perceived usefulness, and trust. The current results indicate that both constraint-based and dedication-based influences are important drivers of the intention to continue using online shopping websites. The data also shows that trust has the strongest total effect on online shoppers' intention to continue using online shopping websites. In addition, the results indicate that the antecedents of constraint-based influences, technical bonds (e.g., perceived operational competence and perceived website interactivity) and social bonds (e.g., perceived relationship investment, community building, and intimacy) have indirect positive effects on the intention to continue using online shopping websites. Based on these findings, this research suggests that online shopping websites should build constraint-based and dedication-based influences to enhance user's continued online shopping behaviors simultaneously.

Efficient Searching with Linear Constraints

DEFF Research Database (Denmark)

Agarwal, Pankaj K.; Arge, Lars Allan; Erickson, Jeff

2000-01-01

We show how to preprocess a set S of points in d into an external memory data structure that efficiently supports linear-constraint queries. Each query is in the form of a linear constraint xd a0+∑d−1i=1 aixi; the data structure must report all the points of S that satisfy the constraint. This pr...

Constraint qualifications and optimality conditions for optimization problems with cardinality constraints

Czech Academy of Sciences Publication Activity Database

Červinka, Michal; Kanzow, Ch.; Schwartz, A.

2016-01-01

Roč. 160, č. 1 (2016), s. 353-377 ISSN 0025-5610 R&D Projects: GA ČR GAP402/12/1309; GA ČR GA15-00735S Institutional support: RVO:67985556 Keywords : Cardinality constraints * Constraint qualifications * Optimality conditions * KKT conditions * Strongly stationary points Subject RIV: BA - General Mathematics Impact factor: 2.446, year: 2016 http://library.utia.cas.cz/separaty/2016/MTR/cervinka-0461165.pdf

Two novel classes of solvable many-body problems of goldfish type with constraints

Energy Technology Data Exchange (ETDEWEB)

Calogero, F [Dipartimento di Fisica, Universita di Roma ' La Sapienza' , 00185 Rome (Italy); Gomez-Ullate, D [Departamento de Fisica Teorica II, Universidad Complutense, 28040 Madrid (Spain)

2007-05-18

Two novel classes of many-body models with nonlinear interactions 'of goldfish type' are introduced. They are solvable provided the initial data satisfy a single constraint (in one case; in the other, two constraints), i.e., for such initial data the solution of their initial-value problem can be achieved via algebraic operations, such as finding the eigenvalues of given matrices or equivalently the zeros of known polynomials. Entirely isochronous versions of some of these models are also exhibited, i.e., versions of these models whose nonsingular solutions are all completely periodic with the same period.

Simplification of integrity constraints with aggregates and arithmetic built-ins

DEFF Research Database (Denmark)

Martinenghi, Davide

2004-01-01

Both aggregates and arithmetic built-ins are widely used in current database query languages: Aggregates are second-order constructs such as CNT and SUM of SQL; arithmetic built-ins include relational and other mathematical operators that apply to numbers, such as < and +. These features are also...... time, simplified versions of such integrity constraints that can be tested before the execution of any update. In this way, virtually no time is spent for optimization or rollbacks at run time. Both set and bag semantics are considered....... of interest in the context of database integrity constraints: correct and efficient integrity checking is crucial, as, without any guarantee of data consistency, the answers to queries cannot be trusted. In this paper we propose a method of practical relevance that can be used to derive, at database design...

Constraint Specialisation in Horn Clause Verification

DEFF Research Database (Denmark)

Kafle, Bishoksan; Gallagher, John Patrick

2015-01-01

We present a method for specialising the constraints in constrained Horn clauses with respect to a goal. We use abstract interpretation to compute a model of a query-answer transformation of a given set of clauses and a goal. The effect is to propagate the constraints from the goal top......-down and propagate answer constraints bottom-up. Our approach does not unfold the clauses at all; we use the constraints from the model to compute a specialised version of each clause in the program. The approach is independent of the abstract domain and the constraints theory underlying the clauses. Experimental...

Constraint specialisation in Horn clause verification

DEFF Research Database (Denmark)

Kafle, Bishoksan; Gallagher, John Patrick

2017-01-01

We present a method for specialising the constraints in constrained Horn clauses with respect to a goal. We use abstract interpretation to compute a model of a query–answer transformed version of a given set of clauses and a goal. The constraints from the model are then used to compute...... a specialised version of each clause. The effect is to propagate the constraints from the goal top-down and propagate answer constraints bottom-up. The specialisation procedure can be repeated to yield further specialisation. The approach is independent of the abstract domain and the constraint theory...

Multi-Objective Trajectory Optimization of a Hypersonic Reconnaissance Vehicle with Temperature Constraints

Science.gov (United States)

Masternak, Tadeusz J.

This research determines temperature-constrained optimal trajectories for a scramjet-based hypersonic reconnaissance vehicle by developing an optimal control formulation and solving it using a variable order Gauss-Radau quadrature collocation method with a Non-Linear Programming (NLP) solver. The vehicle is assumed to be an air-breathing reconnaissance aircraft that has specified takeoff/landing locations, airborne refueling constraints, specified no-fly zones, and specified targets for sensor data collections. A three degree of freedom scramjet aircraft model is adapted from previous work and includes flight dynamics, aerodynamics, and thermal constraints. Vehicle control is accomplished by controlling angle of attack, roll angle, and propellant mass flow rate. This model is incorporated into an optimal control formulation that includes constraints on both the vehicle and mission parameters, such as avoidance of no-fly zones and coverage of high-value targets. To solve the optimal control formulation, a MATLAB-based package called General Pseudospectral Optimal Control Software (GPOPS-II) is used, which transcribes continuous time optimal control problems into an NLP problem. In addition, since a mission profile can have varying vehicle dynamics and en-route imposed constraints, the optimal control problem formulation can be broken up into several "phases" with differing dynamics and/or varying initial/final constraints. Optimal trajectories are developed using several different performance costs in the optimal control formulation: minimum time, minimum time with control penalties, and maximum range. The resulting analysis demonstrates that optimal trajectories that meet specified mission parameters and constraints can be quickly determined and used for larger-scale operational and campaign planning and execution.

Transmission and capacity pricing and constraints

International Nuclear Information System (INIS)

Fusco, M.

1999-01-01

A series of overhead viewgraphs accompanied this presentation which discussed the following issues regarding the North American electric power industry: (1) capacity pricing transmission constraints, (2) nature of transmission constraints, (3) consequences of transmission constraints, and (4) prices as market evidence. Some solutions suggested for pricing constraints included the development of contingent contracts, back-up power in supply regions, and new line capacity construction. 8 tabs., 20 figs

Cross-layer Energy Optimization Under Image Quality Constraints for Wireless Image Transmissions.

Science.gov (United States)

Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

2012-01-01

Wireless image transmission is critical in many applications, such as surveillance and environment monitoring. In order to make the best use of the limited energy of the battery-operated cameras, while satisfying the application-level image quality constraints, cross-layer design is critical. In this paper, we develop an image transmission model that allows the application layer (e.g., the user) to specify an image quality constraint, and optimizes the lower layer parameters of transmit power and packet length, to minimize the energy dissipation in image transmission over a given distance. The effectiveness of this approach is evaluated by applying the proposed energy optimization to a reference ZigBee system and a WiFi system, and also by comparing to an energy optimization study that does not consider any image quality constraint. Evaluations show that our scheme outperforms the default settings of the investigated commercial devices and saves a significant amount of energy at middle-to-large transmission distances.

Evaluating Distributed Timing Constraints

DEFF Research Database (Denmark)

Kristensen, C.H.; Drejer, N.

1994-01-01

In this paper we describe a solution to the problem of implementing time-optimal evaluation of timing constraints in distributed real-time systems.......In this paper we describe a solution to the problem of implementing time-optimal evaluation of timing constraints in distributed real-time systems....

Thermomechanical constraints and constitutive formulations in thermoelasticity

Directory of Open Access Journals (Sweden)

Baek S.

2003-01-01

Full Text Available We investigate three classes of constraints in a thermoelastic body: (i a deformation-temperature constraint, (ii a deformation-entropy constraint, and (iii a deformation-energy constraint. These constraints are obtained as limits of unconstrained thermoelastic materials and we show that constraints (ii and (iii are equivalent. By using a limiting procedure, we show that for the constraint (i, the entropy plays the role of a Lagrange multiplier while for (ii and (iii, the absolute temperature plays the role of Lagrange multiplier. We further demonstrate that the governing equations for materials subject to constraint (i are identical to those of an unconstrained material whose internal energy is an affine function of the entropy, while those for materials subject to constraints (ii and (iii are identical to those of an unstrained material whose Helmholtz potential is affine in the absolute temperature. Finally, we model the thermoelastic response of a peroxide-cured vulcanizate of natural rubber and show that imposing the constraint in which the volume change depends only on the internal energy leads to very good predictions (compared to experimental results of the stress and temperature response under isothermal and isentropic conditions.

Team spirit makes the difference: the interactive effects of team work engagement and organizational constraints during a military operation on psychological outcomes afterwards.

Science.gov (United States)

Boermans, S M; Kamphuis, W; Delahaij, R; van den Berg, C; Euwema, M C

2014-12-01

This article prospectively explores the effects of collective team work engagement and organizational constraints during military deployment on individual-level psychological outcomes afterwards. Participants were 971 Dutch peacekeepers within 93 teams who were deployed between the end of 2008 and beginning of 2010, for an average of 4 months, in the International Security Assistance Force. Surveys were administered 2 months into deployment and 6 months afterwards. Multi-level regression analyses demonstrated that team work engagement during deployment moderated the relation between organizational constraints and post-deployment fatigue symptoms. Team members reported less fatigue symptoms after deployment if they were part of highly engaged teams during deployment, particularly when concerns about organizational constraints during deployment were high. In contrast, low team work engagement was related to more fatigue symptoms, particularly when concerns about organizational constraints were high. Contrary to expectations, no effects for team work engagement or organizational constraints were found for post-traumatic growth. The present study highlights that investing in team work engagement is important for those working in highly demanding jobs. © 2014 John Wiley & Sons, Ltd.

EAST kinetic equilibrium reconstruction combining with Polarimeter-Interferometer internal measurement constraints

Science.gov (United States)

Lian, H.; Liu, H. Q.; Li, K.; Zou, Z. Y.; Qian, J. P.; Wu, M. Q.; Li, G. Q.; Zeng, L.; Zang, Q.; Lv, B.; Jie, Y. X.; EAST Team

2017-12-01

Plasma equilibrium reconstruction plays an important role in the tokamak plasma research. With a high temporal and spatial resolution, the POlarimeter-INTerferometer (POINT) system on EAST has provided effective measurements for 102s H-mode operation. Based on internal Faraday rotation measurements provided by the POINT system, the equilibrium reconstruction with a more accurate core current profile constraint has been demonstrated successfully on EAST. Combining other experimental diagnostics and external magnetic fields measurement, the kinetic equilibrium has also been reconstructed on EAST. Take the pressure and edge current information from kinetic EFIT into the equilibrium reconstruction with Faraday rotation constraint, the new equilibrium reconstruction not only provides a more accurate internal current profile but also contains edge current and pressure information. One time slice result using new kinetic equilibrium reconstruction with POINT data constraints is demonstrated in this paper and the result shows there is a reversed shear of q profile and the pressure profile is also contained. The new improved equilibrium reconstruction is greatly helpful to the future theoretical analysis.

Experimental Matching of Instances to Heuristics for Constraint Satisfaction Problems.

Science.gov (United States)

Moreno-Scott, Jorge Humberto; Ortiz-Bayliss, José Carlos; Terashima-Marín, Hugo; Conant-Pablos, Santiago Enrique

2016-01-01

Constraint satisfaction problems are of special interest for the artificial intelligence and operations research community due to their many applications. Although heuristics involved in solving these problems have largely been studied in the past, little is known about the relation between instances and the respective performance of the heuristics used to solve them. This paper focuses on both the exploration of the instance space to identify relations between instances and good performing heuristics and how to use such relations to improve the search. Firstly, the document describes a methodology to explore the instance space of constraint satisfaction problems and evaluate the corresponding performance of six variable ordering heuristics for such instances in order to find regions on the instance space where some heuristics outperform the others. Analyzing such regions favors the understanding of how these heuristics work and contribute to their improvement. Secondly, we use the information gathered from the first stage to predict the most suitable heuristic to use according to the features of the instance currently being solved. This approach proved to be competitive when compared against the heuristics applied in isolation on both randomly generated and structured instances of constraint satisfaction problems.

Proposal of dose constraint values to the patient in diagnostic radiology

International Nuclear Information System (INIS)

Arranz, L.; Sastre, J.M.; Ferrer, N.; Andres, J.C. De; Guibelalde, E.; Tobarra, B.; Madrid, G.

1996-01-01

A dose constraint is the value of an individual dose not to be exceeded in the individual dose distribution considered in an optimization process. The objective of a dose constraints is to set a ceiling to the doses to individual from a source, practice or task which are considered acceptable in the optimization process at the design stage. Implicitly, as C. Zuur states, dose constraints are below the relevant dose limit and usually should be established as local or national levels. Exposures for medical purposes are not subject to dose limits and hence dose constraints were recommended by the ICRP just for occupational and public exposures. However, as an effective tool for optimization for medical exposures, ICRP-60 in paragraph 180 recognizes the value of applying this concept to patient diagnostic radiology with some peculiarities: 'Considerations should be given to the use of dose constraints, or investigation levels, selected by the appropriate professional or regulatory agency, for application in some common diagnostic procedures. They should be applied with flexibility to allow higher cases where indicated by sound clinical judgement.' This paper analyzes retrospectively the dose levels imparted to patient in some common examinations (chest, lumbar spine and mammography) at different optimization stages of different facilities to propose some local constraints for diagnostic examinations. Dose values have been obtained under routine working conditions. Centres included in the survey have been chosen all over Spain, classifying them with particular attention to the following aspects: -Organizational aspects of the diagnostic radiology service, i.e., operational, technical and clinical criteria, as well as quality requirements. - Evaluation and revision of routine medical protocols. -Quality control of the radiological equipment. - Quality criteria for the surveillance of the weekly procedures, with requirements of proper training of die technical staff

The position of a standard optical computer mouse affects cardiorespiratory responses during the operation of a computer under time constraints

Directory of Open Access Journals (Sweden)

Shunji Sako

2014-08-01

Full Text Available Objectives: This study investigated the association between task-induced stress and fatigue by examining the cardiovascular responses of subjects using different mouse positions while operating a computer under time constraints. Material and Methods: The study was participated by 16 young, healthy men and examined the use of optical mouse devices affixed to laptop computers. Two mouse positions were investigated: (1 the distal position (DP, in which the subjects place their forearms on the desk accompanied by the abduction and flexion of their shoulder joints, and (2 the proximal position (PP, in which the subjects place only their wrists on the desk without using an armrest. The subjects continued each task for 16 min. We assessed differences in several characteristics according to mouse position, including expired gas values, autonomic nerve activities (based on cardiorespiratory responses, operating efficiencies (based on word counts, and fatigue levels (based on the visual analog scale – VAS. Results: Oxygen consumption (VO2, the ratio of inspiration time to respiration time (Ti/Ttotal, respiratory rate (RR, minute ventilation (VE, and the ratio of expiration to inspiration (Te/Ti were significantly lower when the participants were performing the task in the DP than those obtained in the PP. Tidal volume (VT, carbon dioxide output rates (VCO2/VE, and oxygen extraction fractions (VO2/VE were significantly higher for the DP than they were for the PP. No significant difference in VAS was observed between the positions; however, as the task progressed, autonomic nerve activities were lower and operating efficiencies were significantly higher for the DP than they were for the PP. Conclusions: Our results suggest that the DP has fewer effects on cardiorespiratory functions, causes lower levels of sympathetic nerve activity and mental stress, and produces a higher total workload than the PP. This suggests that the DP is preferable to the PP when

Applied Operations Research: Operator's Assistant

Science.gov (United States)

Cole, Stuart K.

2015-01-01

NASA operates high value critical equipment (HVCE) that requires trouble shooting, periodic maintenance and continued monitoring by Operations staff. The complexity HVCE and information required to maintain and trouble shoot HVCE to assure continued mission success as paper is voluminous. Training on new HVCE is commensurate with the need for equipment maintenance. LaRC Research Directorate has undertaken a proactive research to support Operations staff by initiation of the development and prototyping an electronic computer based portable maintenance aid (Operator's Assistant). This research established a goal with multiple objectives and a working prototype was developed. The research identified affordable solutions; constraints; demonstrated use of commercial off the shelf software; use of the US Coast Guard maintenance solution; NASA Procedure Representation Language; and the identification of computer system strategies; where these demonstrations and capabilities support the Operator, and maintenance. The results revealed validation against measures of effectiveness and overall proved a substantial training and capability sustainment tool. The research indicated that the OA could be deployed operationally at the LaRC Compressor Station with an expectation of satisfactorily results and to obtain additional lessons learned prior to deployment at other LaRC Research Directorate Facilities. The research revealed projected cost and time savings.

1/f and the Earthquake Problem: Scaling constraints that facilitate operational earthquake forecasting

Science.gov (United States)

yoder, M. R.; Rundle, J. B.; Turcotte, D. L.

2012-12-01

The difficulty of forecasting earthquakes can fundamentally be attributed to the self-similar, or "1/f", nature of seismic sequences. Specifically, the rate of occurrence of earthquakes is inversely proportional to their magnitude m, or more accurately to their scalar moment M. With respect to this "1/f problem," it can be argued that catalog selection (or equivalently, determining catalog constraints) constitutes the most significant challenge to seismicity based earthquake forecasting. Here, we address and introduce a potential solution to this most daunting problem. Specifically, we introduce a framework to constrain, or partition, an earthquake catalog (a study region) in order to resolve local seismicity. In particular, we combine Gutenberg-Richter (GR), rupture length, and Omori scaling with various empirical measurements to relate the size (spatial and temporal extents) of a study area (or bins within a study area) to the local earthquake magnitude potential - the magnitude of earthquake the region is expected to experience. From this, we introduce a new type of time dependent hazard map for which the tuning parameter space is nearly fully constrained. In a similar fashion, by combining various scaling relations and also by incorporating finite extents (rupture length, area, and duration) as constraints, we develop a method to estimate the Omori (temporal) and spatial aftershock decay parameters as a function of the parent earthquake's magnitude m. From this formulation, we develop an ETAS type model that overcomes many point-source limitations of contemporary ETAS. These models demonstrate promise with respect to earthquake forecasting applications. Moreover, the methods employed suggest a general framework whereby earthquake and other complex-system, 1/f type, problems can be constrained from scaling relations and finite extents.; Record-breaking hazard map of southern California, 2012-08-06. "Warm" colors indicate local acceleration (elevated hazard

Quantum canonical ensemble: A projection operator approach

Science.gov (United States)

Magnus, Wim; Lemmens, Lucien; Brosens, Fons

2017-09-01

Knowing the exact number of particles N, and taking this knowledge into account, the quantum canonical ensemble imposes a constraint on the occupation number operators. The constraint particularly hampers the systematic calculation of the partition function and any relevant thermodynamic expectation value for arbitrary but fixed N. On the other hand, fixing only the average number of particles, one may remove the above constraint and simply factorize the traces in Fock space into traces over single-particle states. As is well known, that would be the strategy of the grand-canonical ensemble which, however, comes with an additional Lagrange multiplier to impose the average number of particles. The appearance of this multiplier can be avoided by invoking a projection operator that enables a constraint-free computation of the partition function and its derived quantities in the canonical ensemble, at the price of an angular or contour integration. Introduced in the recent past to handle various issues related to particle-number projected statistics, the projection operator approach proves beneficial to a wide variety of problems in condensed matter physics for which the canonical ensemble offers a natural and appropriate environment. In this light, we present a systematic treatment of the canonical ensemble that embeds the projection operator into the formalism of second quantization while explicitly fixing N, the very number of particles rather than the average. Being applicable to both bosonic and fermionic systems in arbitrary dimensions, transparent integral representations are provided for the partition function ZN and the Helmholtz free energy FN as well as for two- and four-point correlation functions. The chemical potential is not a Lagrange multiplier regulating the average particle number but can be extracted from FN+1 -FN, as illustrated for a two-dimensional fermion gas.

Ant colony optimization and constraint programming

CERN Document Server

Solnon, Christine

2013-01-01

Ant colony optimization is a metaheuristic which has been successfully applied to a wide range of combinatorial optimization problems. The author describes this metaheuristic and studies its efficiency for solving some hard combinatorial problems, with a specific focus on constraint programming. The text is organized into three parts. The first part introduces constraint programming, which provides high level features to declaratively model problems by means of constraints. It describes the main existing approaches for solving constraint satisfaction problems, including complete tree search

An operational decision support framework for monitoring business constraints

NARCIS (Netherlands)

Maggi, F.M.; Montali, M.; Aalst, van der W.M.P.; Lara, de J.; Zisman, A.

2012-01-01

Only recently, process mining techniques emerged that can be used for Operational decision Support (OS), i.e., knowledge extracted from event logs is used to handle running process instances better. In the process mining tool ProM, a generic OS service has been developed that allows ProM to

Operational constraints and hydrologic variability limit hydropower in supporting wind integration

International Nuclear Information System (INIS)

Fernandez, Alisha R; Blumsack, Seth A; Reed, Patrick M

2013-01-01

Climate change mitigation will require rapid adoption of low-carbon energy resources. The integration of large-scale wind energy in the United States (US) will require controllable assets to balance the variability of wind energy production. Previous work has identified hydropower as an advantageous asset, due to its flexibility and low-carbon emissions production. While many dams currently provide energy and environmental services in the US and globally, we find that multi-use hydropower facilities would face significant policy conflicts if asked to store and release water to accommodate wind integration. Specifically, we develop a model simulating hydroelectric operational decisions when the electric facility is able to provide wind integration services through a mechanism that we term ‘flex reserves’. We use Kerr Dam in North Carolina as a case study, simulating operations under two alternative reservoir policies, one reflecting current policies and the other regulating flow levels to promote downstream ecosystem conservation. Even under perfect information and significant pricing incentives, Kerr Dam faces operational conflicts when providing any substantial levels of flex reserves while also maintaining releases consistent with other river management requirements. These operational conflicts are severely exacerbated during periods of drought. Increase of payments for flex reserves does not resolve these operational and policy conflicts. (letter)

Optimal dynamic voltage scaling for wireless sensor nodes with real-time constraints

Science.gov (United States)

Cassandras, Christos G.; Zhuang, Shixin

2005-11-01

Sensors are increasingly embedded in manufacturing systems and wirelessly networked to monitor and manage operations ranging from process and inventory control to tracking equipment and even post-manufacturing product monitoring. In building such sensor networks, a critical issue is the limited and hard to replenish energy in the devices involved. Dynamic voltage scaling is a technique that controls the operating voltage of a processor to provide desired performance while conserving energy and prolonging the overall network's lifetime. We consider such power-limited devices processing time-critical tasks which are non-preemptive, aperiodic and have uncertain arrival times. We treat voltage scaling as a dynamic optimization problem whose objective is to minimize energy consumption subject to hard or soft real-time execution constraints. In the case of hard constraints, we build on prior work (which engages a voltage scaling controller at task completion times) by developing an intra-task controller that acts at all arrival times of incoming tasks. We show that this optimization problem can be decomposed into two simpler ones whose solution leads to an algorithm that does not actually require solving any nonlinear programming problems. In the case of soft constraints, this decomposition must be partly relaxed, but it still leads to a scalable (linear in the number of tasks) algorithm. Simulation results are provided to illustrate performance improvements in systems with intra-task controllers compared to uncontrolled systems or those using inter-task control.

A new spin on causality constraints

Energy Technology Data Exchange (ETDEWEB)

Hartman, Thomas; Jain, Sachin; Kundu, Sandipan [Department of Physics, Cornell University, Ithaca, New York (United States)

2016-10-26

Causality in a shockwave state is related to the analytic properties of a four-point correlation function. Extending recent results for scalar probes, we show that this constrains the couplings of the stress tensor to light spinning operators in conformal field theory, and interpret these constraints in terms of the interaction with null energy. For spin-1 and spin-2 conserved currents in four dimensions, the resulting inequalities are a subset of the Hofman-Maldacena conditions for positive energy deposition. It is well known that energy conditions in holographic theories are related to causality on the gravity side; our results make a connection on the CFT side, and extend it to non-holographic theories.

Fuzzy Constraint-Based Agent Negotiation

Institute of Scientific and Technical Information of China (English)

Menq-Wen Lin; K. Robert Lai; Ting-Jung Yu

2005-01-01

Conflicts between two or more parties arise for various reasons and perspectives. Thus, resolution of conflicts frequently relies on some form of negotiation. This paper presents a general problem-solving framework for modeling multi-issue multilateral negotiation using fuzzy constraints. Agent negotiation is formulated as a distributed fuzzy constraint satisfaction problem (DFCSP). Fuzzy constrains are thus used to naturally represent each agent's desires involving imprecision and human conceptualization, particularly when lexical imprecision and subjective matters are concerned. On the other hand, based on fuzzy constraint-based problem-solving, our approach enables an agent not only to systematically relax fuzzy constraints to generate a proposal, but also to employ fuzzy similarity to select the alternative that is subject to its acceptability by the opponents. This task of problem-solving is to reach an agreement that benefits all agents with a high satisfaction degree of fuzzy constraints, and move towards the deal more quickly since their search focuses only on the feasible solution space. An application to multilateral negotiation of a travel planning is provided to demonstrate the usefulness and effectiveness of our framework.

Power system operational security analysis to obtain sustainable, strategic and economic dispatch

International Nuclear Information System (INIS)

Khan, R.A.J.; Alemadi, N.; Mulla, Y.A.; Choudhry, T.M.

2006-01-01

This paper addresses the most critical question that is static/online security system n power system operation and managements. Therefore, we do originated couple of models with their operational scenarios. How to identify the main security constraints and their most suitable reinforcements needed to maintain the system security as per determine boundary. It would also render instrumental approach to enhance the security operational constraints. Therefore, it will also provide the system operator to take preventive action or formulate the action plan prior to contingencies occurred In past the both demand side management system and load shedding have been used for to provide reliable power system under normal or emergency operation and control [4,5 J.) (author)

Optimal residential smart appliances scheduling considering distribution network constraints

Directory of Open Access Journals (Sweden)

Yu-Ree Kim

2016-01-01

Full Text Available As smart appliances (SAs are more widely adopted within distribution networks, residential consumers can contribute to electricity market operations with demand response resources and reduce their electricity bill. However, if the schedules of demand response resources are determined only by the economic electricity rate signal, the schedule can be unfeasible due to the distribution network constraints. Furthermore, it is impossible for consumers to understand the complex physical characteristics and reflect them in their everyday behaviors. This paper introduces the concept of load coordinating retailer (LCR that deals with demand responsive appliances to reduce electrical consumption for the given distribution network constraints. The LCR can play the role of both conventional retailer and aggregated demand response provider for residential customers. It determines the optimal schedules for the aggregated neighboring SAs according to their types within each distribution feeder. The optimization algorithms are developed using Mixed Integer Linear Programming, and the distribution network is solved by the Newton–Raphson AC power flow.

Notes on Timed Concurrent Constraint Programming

DEFF Research Database (Denmark)

Nielsen, Mogens; Valencia, Frank D.

2004-01-01

and program reactive systems. This note provides a comprehensive introduction to the background for and central notions from the theory of tccp. Furthermore, it surveys recent results on a particular tccp calculus, ntcc, and it provides a classification of the expressive power of various tccp languages.......A constraint is a piece of (partial) information on the values of the variables of a system. Concurrent constraint programming (ccp) is a model of concurrency in which agents (also called processes) interact by telling and asking information (constraints) to and from a shared store (a constraint...

Multi-objective congestion management by modified augmented ε-constraint method

International Nuclear Information System (INIS)

Esmaili, Masoud; Shayanfar, Heidar Ali; Amjady, Nima

2011-01-01

Congestion management is a vital part of power system operations in recent deregulated electricity markets. However, after relieving congestion, power systems may be operated with a reduced voltage or transient stability margin because of hitting security limits or increasing the contribution of risky participants. Therefore, power system stability margins should be considered within the congestion management framework. The multi-objective congestion management provides not only more security but also more flexibility than single-objective methods. In this paper, a multi-objective congestion management framework is presented while simultaneously optimizing the competing objective functions of congestion management cost, voltage security, and dynamic security. The proposed multi-objective framework, called modified augmented ε-constraint method, is based on the augmented ε-constraint technique hybridized by the weighting method. The proposed framework generates candidate solutions for the multi-objective problem including only efficient Pareto surface enhancing the competitiveness and economic effectiveness of the power market. Besides, the relative importance of the objective functions is explicitly modeled in the proposed framework. Results of testing the proposed multi-objective congestion management method on the New-England test system are presented and compared with those of the previous single objective and multi-objective techniques in detail. These comparisons confirm the efficiency of the developed method. (author)

The constraints

International Nuclear Information System (INIS)

Jones, P.M.S.

1987-01-01

There are considerable incentives for the use of nuclear in preference to other sources for base load electricity generation in most of the developed world. These are economic, strategic, environmental and climatic. However, there are two potential constraints which could hinder the development of nuclear power to its full economic potential. These are public opinion and financial regulations which distort the nuclear economic advantage. The concerns of the anti-nuclear lobby are over safety, (especially following the Chernobyl accident), the management of radioactive waste, the potential effects of large scale exposure of the population to radiation and weapons proliferation. These are discussed. The financial constraint is over two factors, the availability of funds and the perception of cost, both of which are discussed. (U.K.)

System-Level Operational and Adequacy Impact Assessment of Photovoltaic and Distributed Energy Storage, with Consideration of Inertial Constraints, Dynamic Reserve and Interconnection Flexibility

Directory of Open Access Journals (Sweden)

Lingxi Zhang

2017-07-01

Full Text Available The growing penetration of solar photovoltaic (PV systems requires a fundamental understanding of its impact at a system-level. Furthermore, distributed energy storage (DES technologies, such as batteries, are attracting great interest owing to their ability to provide support to systems with large-scale renewable generation, such as PV. In this light, the system-level impacts of PV and DES are assessed from both operational and adequacy perspectives. Different control strategies for DES are proposed, namely: (1 centralised, to support system operation in the presence of increasing requirements on system ramping and frequency control; and (2 decentralised, to maximise the harnessing of solar energy from individual households while storing electricity generated by PV panels to provide system capacity on request. The operational impacts are assessed by deploying a multi-service unit commitment model with consideration of inertial constraints, dynamic reserve allocation, and interconnection flexibility, while the impacts on adequacy of supply are analysed by assessing the capacity credit of PV and DES through different metrics. The models developed are then applied to different future scenarios for the Great Britain power system, whereby an electricity demand increase due to electrification is also considered. The numerical results highlight the importance of interconnectors to provide flexibility. On the other hand, provision of reserves, as opposed to energy arbitrage, from DES that are integrated into system operation is seen as the most effective contribution to improve system performance, which in turn also decreases the role of interconnectors. DES can also contribute to providing system capacity, but to an extent that is limited by their individual and aggregated energy availability under different control strategies.

Vandenberg Air Force Base Upper Level Wind Launch Weather Constraints

Science.gov (United States)

Shafer, Jaclyn A.; Wheeler, Mark M.

2012-01-01

The 30th Operational Support Squadron Weather Flight (30 OSSWF) provides comprehensive weather services to the space program at Vandenberg Air Force Base (VAFB) in California. One of their responsibilities is to monitor upper-level winds to ensure safe launch operations of the Minuteman III ballistic missile. The 30 OSSWF tasked the Applied Meteorology Unit (AMU) to analyze VAFB sounding data with the goal of determining the probability of violating (PoV) their upper-level thresholds for wind speed and shear constraints specific to this launch vehicle, and to develop a tool that will calculate the PoV of each constraint on the day of launch. In order to calculate the probability of exceeding each constraint, the AMU collected and analyzed historical data from VAFB. The historical sounding data were retrieved from the National Oceanic and Atmospheric Administration Earth System Research Laboratory archive for the years 1994-2011 and then stratified into four sub-seasons: January-March, April-June, July-September, and October-December. The maximum wind speed and 1000-ft shear values for each sounding in each subseason were determined. To accurately calculate the PoV, the AMU determined the theoretical distributions that best fit the maximum wind speed and maximum shear datasets. Ultimately it was discovered that the maximum wind speeds follow a Gaussian distribution while the maximum shear values follow a lognormal distribution. These results were applied when calculating the averages and standard deviations needed for the historical and real-time PoV calculations. In addition to the requirements outlined in the original task plan, the AMU also included forecast sounding data from the Rapid Refresh model. This information provides further insight for the launch weather officers (LWOs) when determining if a wind constraint violation will occur over the next few hours on day of launch. The interactive graphical user interface (GUI) for this project was developed in

SYMMETRIC DETERMINATION OF THE SEVERITY OF PRODUCTIVITY CONSTRAINTS OF FISH FARMERS IN THE TROPICS: A CASE STUDY OF THE NIGER DELTA REGION, NIGERIA

Directory of Open Access Journals (Sweden)

VALERIE Solomon

2001-09-01

Full Text Available The study was conducted to fi ll the gap in the dearth of information on systematic approach to ascertain the severity as well as the magnitude of the constraints responsible for the sub-optimal operation of fi sh farming in Nigeria. 120 randomly selected fish farmers from a list of 186 fi sh farmers in the state were interviewed. Participatory appraisal technique and econometric technique were adopted to ascertain the most severe major constraints and also the severity index of each of the sub-constraints that are responsible for the sub-optimal aquaculture operation in the Niger Delta region of Nigeria and the cause of withdrawal from aquaculture by some fi sh farmers. The sub-constraints severity within the major constraints, across the region gave more insight into the causes of the high rate of withdrawals from aquaculture and the decline in aquaculture productivity in the region. How productive the regional aquaculture would be, even in the nearest future, would depend to a large extent on these major factors: production, marketing and advancement in related technology. Unless pragmatic approach is used to reduce the constraints responsible for the high rate of withdrawal, fi sh food security in the Niger Delta Region of Nigeria would still be elusive.

Developmental constraints on behavioural flexibility.

Science.gov (United States)

Holekamp, Kay E; Swanson, Eli M; Van Meter, Page E

2013-05-19

We suggest that variation in mammalian behavioural flexibility not accounted for by current socioecological models may be explained in part by developmental constraints. From our own work, we provide examples of constraints affecting variation in behavioural flexibility, not only among individuals, but also among species and higher taxonomic units. We first implicate organizational maternal effects of androgens in shaping individual differences in aggressive behaviour emitted by female spotted hyaenas throughout the lifespan. We then compare carnivores and primates with respect to their locomotor and craniofacial adaptations. We inquire whether antagonistic selection pressures on the skull might impose differential functional constraints on evolvability of skulls and brains in these two orders, thus ultimately affecting behavioural flexibility in each group. We suggest that, even when carnivores and primates would theoretically benefit from the same adaptations with respect to behavioural flexibility, carnivores may nevertheless exhibit less behavioural flexibility than primates because of constraints imposed by past adaptations in the morphology of the limbs and skull. Phylogenetic analysis consistent with this idea suggests greater evolutionary lability in relative brain size within families of primates than carnivores. Thus, consideration of developmental constraints may help elucidate variation in mammalian behavioural flexibility.

Generalized Pauli constraints in small atoms

DEFF Research Database (Denmark)

Schilling, Christian; Altunbulak, Murat; Knecht, Stefan

2018-01-01

investigations have found evidence that these constraints are exactly saturated in several physically relevant systems, e.g., in a certain electronic state of the beryllium atom. It has been suggested that, in such cases, the constraints, rather than the details of the Hamiltonian, dictate the system......'s qualitative behavior. Here, we revisit this question with state-of-the-art numerical methods for small atoms. We find that the constraints are, in fact, not exactly saturated, but that they lie much closer to the surface defined by the constraints than the geometry of the problem would suggest. While...

Learning With Mixed Hard/Soft Pointwise Constraints.

Science.gov (United States)

Gnecco, Giorgio; Gori, Marco; Melacci, Stefano; Sanguineti, Marcello

2015-09-01

A learning paradigm is proposed and investigated, in which the classical framework of learning from examples is enhanced by the introduction of hard pointwise constraints, i.e., constraints imposed on a finite set of examples that cannot be violated. Such constraints arise, e.g., when requiring coherent decisions of classifiers acting on different views of the same pattern. The classical examples of supervised learning, which can be violated at the cost of some penalization (quantified by the choice of a suitable loss function) play the role of soft pointwise constraints. Constrained variational calculus is exploited to derive a representer theorem that provides a description of the functional structure of the optimal solution to the proposed learning paradigm. It is shown that such an optimal solution can be represented in terms of a set of support constraints, which generalize the concept of support vectors and open the doors to a novel learning paradigm, called support constraint machines. The general theory is applied to derive the representation of the optimal solution to the problem of learning from hard linear pointwise constraints combined with soft pointwise constraints induced by supervised examples. In some cases, closed-form optimal solutions are obtained.

Pareto-optimal reversed-phase chromatography separation of three insulin variants with a solubility constraint.

Science.gov (United States)

Arkell, Karolina; Knutson, Hans-Kristian; Frederiksen, Søren S; Breil, Martin P; Nilsson, Bernt

2018-01-12

With the shift of focus of the regulatory bodies, from fixed process conditions towards flexible ones based on process understanding, model-based optimization is becoming an important tool for process development within the biopharmaceutical industry. In this paper, a multi-objective optimization study of separation of three insulin variants by reversed-phase chromatography (RPC) is presented. The decision variables were the load factor, the concentrations of ethanol and KCl in the eluent, and the cut points for the product pooling. In addition to the purity constraints, a solubility constraint on the total insulin concentration was applied. The insulin solubility is a function of the ethanol concentration in the mobile phase, and the main aim was to investigate the effect of this constraint on the maximal productivity. Multi-objective optimization was performed with and without the solubility constraint, and visualized as Pareto fronts, showing the optimal combinations of the two objectives productivity and yield for each case. Comparison of the constrained and unconstrained Pareto fronts showed that the former diverges when the constraint becomes active, because the increase in productivity with decreasing yield is almost halted. Consequently, we suggest the operating point at which the total outlet concentration of insulin reaches the solubility limit as the most suitable one. According to the results from the constrained optimizations, the maximal productivity on the C 4 adsorbent (0.41 kg/(m 3  column h)) is less than half of that on the C 18 adsorbent (0.87 kg/(m 3  column h)). This is partly caused by the higher selectivity between the insulin variants on the C 18 adsorbent, but the main reason is the difference in how the solubility constraint affects the processes. Since the optimal ethanol concentration for elution on the C 18 adsorbent is higher than for the C 4 one, the insulin solubility is also higher, allowing a higher pool concentration

Resolving kinematic redundancy with constraints using the FSP (Full Space Parameterization) approach

International Nuclear Information System (INIS)

Pin, F.G.; Tulloch, F.A.

1996-01-01

A solution method is presented for the motion planning and control of kinematically redundant serial-link manipulators in the presence of motion constraints such as joint limits or obstacles. Given a trajectory for the end-effector, the approach utilizes the recently proposed Full Space Parameterization (FSP) method to generate a parameterized expression for the entire space of solutions of the unconstrained system. At each time step, a constrained optimization technique is then used to analytically find the specific joint motion solution that satisfies the desired task objective and all the constraints active during the time step. The method is applicable to systems operating in a priori known environments or in unknown environments with sensor-based obstacle detection. The derivation of the analytical solution is first presented for a general type of kinematic constraint and is then applied to the problem of motion planning for redundant manipulators with joint limits and obstacle avoidance. Sample results using planar and 3-D manipulators with various degrees of redundancy are presented to illustrate the efficiency and wide applicability of constrained motion planning using the FSP approach

Short-sale Constraints and Credit Runs

DEFF Research Database (Denmark)

Venter, Gyuri

), creditors with high private signals are more lenient to roll over debt, and a bank with lower asset quality remains solvent. This leads to higher allocative efficiency in the real economy. My result thus implies that the decrease in average informativeness due to short-sale constraints can be more than......This paper studies how short-sale constraints affect the informational efficiency of market prices and the link between prices and economic activity. I show that under short-sale constraints security prices contain less information. However, short-sale constraints increase the informativeness...... the price of an asset the bank holds. I show that short-selling constraints in the financial market lead to the revival of self-fulfilling beliefs about the beliefs and actions of others, and create multiple equilibria. In the equilibrium where agents rely more on public information (i.e., the price...

Mission Implementation Constraints on Planetary Muon Radiography

Science.gov (United States)

Jones, Cathleen E.; Kedar, Sharon; Naudet, Charles; Webb, Frank

2011-01-01

Cost: Use heritage hardware, especially use a tested landing system to reduce cost (Phoenix or MSL EDL stage). The sky crane technology delivers higher mass to the surface and enables reaching targets at higher elevation, but at a higher mission cost. Rover vs. Stationary Lander: Rover-mounted instrument enables tomography, but the increased weight of the rover reduces the allowable payload weight. Mass is the critical design constraint for an instrument for a planetary mission. Many factors that are minor factors or do not enter into design considerations for terrestrial operation are important for a planetary application. (Landing site, diurnal temperature variation, instrument portability, shock/vibration)

Constraint-based Word Segmentation for Chinese

DEFF Research Database (Denmark)

Christiansen, Henning; Bo, Li

2014-01-01

-hoc and statistically based methods. In this paper, we show experiments of implementing different approaches to CWSP in the framework of CHR Grammars [Christiansen, 2005] that provides a constraint solving approach to language analysis. CHR Grammars are based upon Constraint Handling Rules, CHR [Frühwirth, 1998, 2009......], which is a declarative, high-level programming language for specification and implementation of constraint solvers....

Application of multiple tabu search algorithm to solve dynamic economic dispatch considering generator constraints

International Nuclear Information System (INIS)

Pothiya, Saravuth; Ngamroo, Issarachai; Kongprawechnon, Waree

2008-01-01

This paper presents a new optimization technique based on a multiple tabu search algorithm (MTS) to solve the dynamic economic dispatch (ED) problem with generator constraints. In the constrained dynamic ED problem, the load demand and spinning reserve capacity as well as some practical operation constraints of generators, such as ramp rate limits and prohibited operating zone are taken into consideration. The MTS algorithm introduces additional mechanisms such as initialization, adaptive searches, multiple searches, crossover and restarting process. To show its efficiency, the MTS algorithm is applied to solve constrained dynamic ED problems of power systems with 6 and 15 units. The results obtained from the MTS algorithm are compared to those achieved from the conventional approaches, such as simulated annealing (SA), genetic algorithm (GA), tabu search (TS) algorithm and particle swarm optimization (PSO). The experimental results show that the proposed MTS algorithm approaches is able to obtain higher quality solutions efficiently and with less computational time than the conventional approaches

Precision constraints on the top-quark effective field theory at future lepton colliders

Energy Technology Data Exchange (ETDEWEB)

Durieux, Gauthier

2017-08-15

We examine the constraints that future lepton colliders would impose on the effective field theory describing modifications of top-quark interactions beyond the standard model, through measurements of the e{sup +}e{sup -}→bW{sup +} anti bW{sup -} process. Statistically optimal observables are exploited to constrain simultaneously and efficiently all relevant operators. Their constraining power is sufficient for quadratic effective-field-theory contributions to have negligible impact on limits which are therefore basis independent. This is contrasted with the measurements of cross sections and forward-backward asymmetries. An overall measure of constraints strength, the global determinant parameter, is used to determine which run parameters impose the strongest restriction on the multidimensional effective-field-theory parameter space.

Precision constraints on the top-quark effective field theory at future lepton colliders

International Nuclear Information System (INIS)

Durieux, Gauthier

2017-08-01

We examine the constraints that future lepton colliders would impose on the effective field theory describing modifications of top-quark interactions beyond the standard model, through measurements of the e + e - →bW + anti bW - process. Statistically optimal observables are exploited to constrain simultaneously and efficiently all relevant operators. Their constraining power is sufficient for quadratic effective-field-theory contributions to have negligible impact on limits which are therefore basis independent. This is contrasted with the measurements of cross sections and forward-backward asymmetries. An overall measure of constraints strength, the global determinant parameter, is used to determine which run parameters impose the strongest restriction on the multidimensional effective-field-theory parameter space.

Back-feed power restoration using distributed constraint optimization in smart distribution grids clustered into microgrids

International Nuclear Information System (INIS)

El-Sharafy, M. Zaki; Farag, Hany E.Z.

2017-01-01

Highlights: •Introducing three types of energy transfer between neighboring microgrids. •Incorporating droop-based power flow model of islanded microgrids in restoration. •Optimizing droop settings of DGs in islanded mode to maximize restored load. •Decomposing restoration into two distributed constraint optimization problems. •Using OPTAPO to solve the formulated problems in a multiagent environment. -- Abstract: In this paper, an optimization problem is formulated for the automatic back-feed service restoration in smart distribution grids. The formulated problem relies on the structure of smart distribution grids, clustered into multi-microgrids, capable of operating in both grid-connected and islanded modes of operation. To that end, three types of power transfer between the neighboring microgrids, during the restoration processes are introduced: load transfer, distributed generation (DG) transfer, and combined load–DG transfer. The formulated optimization problem takes into account the ability of forming new, not predefined islanded microgrids, in the post-restoration configuration, to maximize service restoration. To obviate the need for a central unit, the optimization problem is reformulated, in this work, as a distributed constraint optimization problem, in which the variables and constraints are distributed among automated agents. To reduce the problem complexity, the restoration problem is decomposed into two sequential and interdependent distributed sub-problems: supply adequacy, and optimal reconfiguration. The proposed algorithm adopts the Optimal Asynchronous Partial Overlay (OPTAPO) technique, which is based on the distributed constraint agent search to solve distributed sub-problems in a multi-agent environment. Several case studies have been carried out to evaluate the effectiveness and robustness of the proposed algorithm.

Generalized Pauli constraints in small atoms

Science.gov (United States)

Schilling, Christian; Altunbulak, Murat; Knecht, Stefan; Lopes, Alexandre; Whitfield, James D.; Christandl, Matthias; Gross, David; Reiher, Markus

2018-05-01

The natural occupation numbers of fermionic systems are subject to nontrivial constraints, which include and extend the original Pauli principle. A recent mathematical breakthrough has clarified their mathematical structure and has opened up the possibility of a systematic analysis. Early investigations have found evidence that these constraints are exactly saturated in several physically relevant systems, e.g., in a certain electronic state of the beryllium atom. It has been suggested that, in such cases, the constraints, rather than the details of the Hamiltonian, dictate the system's qualitative behavior. Here, we revisit this question with state-of-the-art numerical methods for small atoms. We find that the constraints are, in fact, not exactly saturated, but that they lie much closer to the surface defined by the constraints than the geometry of the problem would suggest. While the results seem incompatible with the statement that the generalized Pauli constraints drive the behavior of these systems, they suggest that the qualitatively correct wave-function expansions can in some systems already be obtained on the basis of a limited number of Slater determinants, which is in line with numerical evidence from quantum chemistry.

University Course Timetabling using Constraint Programming

Directory of Open Access Journals (Sweden)

Hadi Shahmoradi

2017-03-01

Full Text Available University course timetabling problem is a challenging and time-consuming task on the overall structure of timetable in every academic environment. The problem deals with many factors such as the number of lessons, classes, teachers, students and working time, and these are influenced by some hard and soft constraints. The aim of solving this problem is to assign courses and classes to teachers and students, so that the restrictions are held. In this paper, a constraint programming method is proposed to satisfy maximum constraints and expectation, in order to address university timetabling problem. For minimizing the penalty of soft constraints, a cost function is introduced and AHP method is used for calculating its coefficients. The proposed model is tested on department of management, University of Isfahan dataset using OPL on the IBM ILOG CPLEX Optimization Studio platform. A statistical analysis has been conducted and shows the performance of the proposed approach in satisfying all hard constraints and also the satisfying degree of the soft constraints is on maximum desirable level. The running time of the model is less than 20 minutes that is significantly better than the non-automated ones.

Psychological constraints on egalitarianism

DEFF Research Database (Denmark)

Kasperbauer, Tyler Joshua

2015-01-01

processes motivating people to resist various aspects of egalitarianism. I argue for two theses, one normative and one descriptive. The normative thesis holds that egalitarians must take psychological constraints into account when constructing egalitarian ideals. I draw from non-ideal theories in political...... philosophy, which aim to construct moral goals with current social and political constraints in mind, to argue that human psychology must be part of a non-ideal theory of egalitarianism. The descriptive thesis holds that the most fundamental psychological challenge to egalitarian ideals comes from what......Debates over egalitarianism for the most part are not concerned with constraints on achieving an egalitarian society, beyond discussions of the deficiencies of egalitarian theory itself. This paper looks beyond objections to egalitarianism as such and investigates the relevant psychological...

Constraint Programming for Context Comprehension

DEFF Research Database (Denmark)

Christiansen, Henning

2014-01-01

A close similarity is demonstrated between context comprehension, such as discourse analysis, and constraint programming. The constraint store takes the role of a growing knowledge base learned throughout the discourse, and a suitable con- straint solver does the job of incorporating new pieces...

Improving the Operations of the Earth Observing One Mission via Automated Mission Planning

Science.gov (United States)

Chien, Steve A.; Tran, Daniel; Rabideau, Gregg; Schaffer, Steve; Mandl, Daniel; Frye, Stuart

2010-01-01

We describe the modeling and reasoning about operations constraints in an automated mission planning system for an earth observing satellite - EO-1. We first discuss the large number of elements that can be naturally represented in an expressive planning and scheduling framework. We then describe a number of constraints that challenge the current state of the art in automated planning systems and discuss how we modeled these constraints as well as discuss tradeoffs in representation versus efficiency. Finally we describe the challenges in efficiently generating operations plans for this mission. These discussions involve lessons learned from an operations model that has been in use since Fall 2004 (called R4) as well as a newer more accurate operations model operational since June 2009 (called R5). We present analysis of the R5 software documenting a significant (greater than 50%) increase in the number of weekly observations scheduled by the EO-1 mission. We also show that the R5 mission planning system produces schedules within 15% of an upper bound on optimal schedules. This operational enhancement has created value of millions of dollars US over the projected remaining lifetime of the EO-1 mission.

Runway Operations Planning: A Two-Stage Solution Methodology

Science.gov (United States)

Anagnostakis, Ioannis; Clarke, John-Paul

2003-01-01

The airport runway is a scarce resource that must be shared by different runway operations (arrivals, departures and runway crossings). Given the possible sequences of runway events, careful Runway Operations Planning (ROP) is required if runway utilization is to be maximized. Thus, Runway Operations Planning (ROP) is a critical component of airport operations planning in general and surface operations planning in particular. From the perspective of departures, ROP solutions are aircraft departure schedules developed by optimally allocating runway time for departures given the time required for arrivals and crossings. In addition to the obvious objective of maximizing throughput, other objectives, such as guaranteeing fairness and minimizing environmental impact, may be incorporated into the ROP solution subject to constraints introduced by Air Traffic Control (ATC) procedures. Generating optimal runway operations plans was approached in with a 'one-stage' optimization routine that considered all the desired objectives and constraints, and the characteristics of each aircraft (weight class, destination, Air Traffic Control (ATC) constraints) at the same time. Since, however, at any given point in time, there is less uncertainty in the predicted demand for departure resources in terms of weight class than in terms of specific aircraft, the ROP problem can be parsed into two stages. In the context of the Departure Planner (OP) research project, this paper introduces Runway Operations Planning (ROP) as part of the wider Surface Operations Optimization (SOO) and describes a proposed 'two stage' heuristic algorithm for solving the Runway Operations Planning (ROP) problem. Focus is specifically given on including runway crossings in the planning process of runway operations. In the first stage, sequences of departure class slots and runwy crossings slots are generated and ranked based on departure runway throughput under stochastic conditions. In the second stage, the

Robust nonlinear model predictive control for nuclear power plants in load following operations with bounded xenon oscillations

International Nuclear Information System (INIS)

Eliasi, H.; Menhaj, M.B.; Davilu, H.

2011-01-01

Research highlights: → In this work, a robust nonlinear model predictive control algorithm is developed. → This algorithm is applied to control the power level for load following. → The state constraints are imposed on the predicted trajectory during optimization. → The xenon oscillations are the main constraint for the load following problem. → In this algorithm, xenon oscillations are bounded within acceptable limits. - Abstract: One of the important operations in nuclear power plants is load-following in which imbalance of axial power distribution induces xenon oscillations. These oscillations must be maintained within acceptable limits otherwise the nuclear power plant could become unstable. Therefore, bounded xenon oscillation considered to be a constraint for the load-following operation. In this paper, a robust nonlinear model predictive control for the load-following operation problem is proposed that ensures xenon oscillations are kept bounded within acceptable limits. The proposed controller uses constant axial offset (AO) strategy to maintain xenon oscillations to be bounded. The constant AO is a robust state constraint for load-following problem. The controller imposes restricted state constraints on the predicted trajectory during optimization which guarantees robust satisfaction of state constraints without restoring to a min-max optimization problem. Simulation results show that the proposed controller for the load-following operation is so effective so that the xenon oscillations kept bounded in the given region.

Some cosmological constraints on gauge theories

International Nuclear Information System (INIS)

Schramm, D.N.

1983-01-01

In these lectures, a review is made of various constraints cosmology may place on gauge theories. Particular emphasis is placed on those constraints obtainable from Big Bang Nucleosynthesis, with only brief mention made of Big Bang Baryosynthesis. There is also a considerable discussion of astrophysical constraints on masses and lifetimes of neutrinos with specific mention of the 'missing mass (light)' problem of galactic dynamics. (orig./HSI)

Dynamics and causality constraints

International Nuclear Information System (INIS)

Sousa, Manoelito M. de

2001-04-01

The physical meaning and the geometrical interpretation of causality implementation in classical field theories are discussed. Causality in field theory are kinematical constraints dynamically implemented via solutions of the field equation, but in a limit of zero-distance from the field sources part of these constraints carries a dynamical content that explains old problems of classical electrodynamics away with deep implications to the nature of physicals interactions. (author)

Engineering design constraints of the lunar surface environment

Science.gov (United States)

Morrison, D. A.

1992-01-01

Living and working on the lunar surface will be difficult. Design of habitats, machines, tools, and operational scenarios in order to allow maximum flexibility in human activity will require paying attention to certain constraints imposed by conditions at the surface and the characteristics of lunar material. Primary design drivers for habitat, crew health and safety, and crew equipment are: ionizing radiation, the meteoroid flux, and the thermal environment. Secondary constraints for engineering derive from: the physical and chemical properties of lunar surface materials, rock distributions and regolith thicknesses, topography, electromagnetic properties, and seismicity. Protection from ionizing radiation is essential for crew health and safety. The total dose acquired by a crew member will be the sum of the dose acquired during EVA time (when shielding will be least) plus the dose acquired during time spent in the habitat (when shielding will be maximum). Minimizing the dose acquired in the habitat extends the time allowable for EVA's before a dose limit is reached. Habitat shielding is enabling, and higher precision in predicting secondary fluxes produced in shielding material would be desirable. Means for minimizing dose during a solar flare event while on extended EVA will be essential. Early warning of the onset of flare activity (at least a half-hour is feasible) will dictate the time available to take mitigating steps. Warning capability affects design of rovers (or rover tools) and site layout. Uncertainty in solar flare timing is a design constraint that points to the need for quickly accessible or constructible safe havens.

Data assimilation with inequality constraints

Science.gov (United States)

Thacker, W. C.

If values of variables in a numerical model are limited to specified ranges, these restrictions should be enforced when data are assimilated. The simplest option is to assimilate without regard for constraints and then to correct any violations without worrying about additional corrections implied by correlated errors. This paper addresses the incorporation of inequality constraints into the standard variational framework of optimal interpolation with emphasis on our limited knowledge of the underlying probability distributions. Simple examples involving only two or three variables are used to illustrate graphically how active constraints can be treated as error-free data when background errors obey a truncated multi-normal distribution. Using Lagrange multipliers, the formalism is expanded to encompass the active constraints. Two algorithms are presented, both relying on a solution ignoring the inequality constraints to discover violations to be enforced. While explicitly enforcing a subset can, via correlations, correct the others, pragmatism based on our poor knowledge of the underlying probability distributions suggests the expedient of enforcing them all explicitly to avoid the computationally expensive task of determining the minimum active set. If additional violations are encountered with these solutions, the process can be repeated. Simple examples are used to illustrate the algorithms and to examine the nature of the corrections implied by correlated errors.

Modeling and sliding mode predictive control of the ultra-supercritical boiler-turbine system with uncertainties and input constraints.

Science.gov (United States)

Tian, Zhen; Yuan, Jingqi; Zhang, Xiang; Kong, Lei; Wang, Jingcheng

2018-05-01

The coordinated control system (CCS) serves as an important role in load regulation, efficiency optimization and pollutant reduction for coal-fired power plants. The CCS faces with tough challenges, such as the wide-range load variation, various uncertainties and constraints. This paper aims to improve the load tacking ability and robustness for boiler-turbine units under wide-range operation. To capture the key dynamics of the ultra-supercritical boiler-turbine system, a nonlinear control-oriented model is developed based on mechanism analysis and model reduction techniques, which is validated with the history operation data of a real 1000 MW unit. To simultaneously address the issues of uncertainties and input constraints, a discrete-time sliding mode predictive controller (SMPC) is designed with the dual-mode control law. Moreover, the input-to-state stability and robustness of the closed-loop system are proved. Simulation results are presented to illustrate the effectiveness of the proposed control scheme, which achieves good tracking performance, disturbance rejection ability and compatibility to input constraints. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

A neural network approach to breast cancer diagnosis as a constraint satisfaction problem

International Nuclear Information System (INIS)

Tourassi, Georgia D.; Markey, Mia K.; Lo, Joseph Y.; Floyd, Carey E. Jr.

2001-01-01

A constraint satisfaction neural network (CSNN) approach is proposed for breast cancer diagnosis using mammographic and patient history findings. Initially, the diagnostic decision to biopsy was formulated as a constraint satisfaction problem. Then, an associative memory type neural network was applied to solve the problem. The proposed network has a flexible, nonhierarchical architecture that allows it to operate not only as a predictive tool but also as an analysis tool for knowledge discovery of association rules. The CSNN was developed and evaluated using a database of 500 nonpalpable breast lesions with definitive histopathological diagnosis. The CSNN diagnostic performance was evaluated using receiver operating characteristic analysis (ROC). The results of the study showed that the CSNN ROC area index was 0.84±0.02. The CSNN predictive performance is competitive with that achieved by experienced radiologists and backpropagation artificial neural networks (BP-ANNs) presented before. Furthermore, the study illustrates how CSNN can be used as a knowledge discovery tool overcoming some of the well-known limitations of BP-ANNs

Operator-in-the-loop simulation of a redundant manipulator under teleoperation

International Nuclear Information System (INIS)

Yae, K.H.; Lin, T.C.; Chern, S.T.

1993-01-01

For an interactive simulation of 7 degree-of-freedom redundant manipulator under teleoperation, this paper describes an iterative form of resolved-motion rate control in which the constraint Jacobian is constructed on-line in real time and used in the pseudoinverse method as the manipulator is teleoperated. The manipulator's tasks may involve trajectory following in free space and frequent contact with the environment through pick-and-put operation. The operator's command is interpreted as a series of increments in Cartesian space, and then the constraint Jacobian is developed between two successive increments by viewing the predecessor as the initial configuration and the successor as the target configuration. The pseudoinverse of the constraint Jacobian then generates necessary changes in joint variables and subsequently joint torque. The Jacobian constructed in this way enables us to treat both free motion and environmental contact in the same way. The simulator is built on a two-processor IRIS workstation, with one processor for graphics and the other for dynamics and control analysis. This simulator has a potential for training the teleoperator, developing operational scenarios through visualization of the simulation, and testing the design of operator-machine interface

Use of dose constraints in public exposure

International Nuclear Information System (INIS)

Tageldein, Amged

2015-02-01

An overview of the dose constraints in public exposures has been carried out in this project. The establishment, development and the application of the concept of dose constraints are reviewed with regards to public exposure. The role of dose constraints in the process of optimization of radiation protection was described and has been showed that the concept of the dose constraints along with many other concept of radiation protection is widely applied in the optimization of exposure to radiation. From the beginning of the establishment of dose constraints as a concept in radiation protection, the International Commission of Radiological Protection (ICRP) has published a number of documents that provides detailed application related to radiation protection and safety of public exposure from ionizing radiation. This work provides an overview of such publications and related documents with special emphasis on optimization of public exposure using dose constraints. (au)

Self-scheduling and bidding strategies of thermal units with stochastic emission constraints

International Nuclear Information System (INIS)

Laia, R.; Pousinho, H.M.I.; Melíco, R.; Mendes, V.M.F.

2015-01-01

Highlights: • The management of thermal power plants is considered for different emission allowance levels. • The uncertainty on electricity price is considered by a set of scenarios. • A stochastic MILP approach allows devising the bidding strategies and hedging against price uncertainty and emission allowances. - Abstract: This paper is on the self-scheduling problem for a thermal power producer taking part in a pool-based electricity market as a price-taker, having bilateral contracts and emission-constrained. An approach based on stochastic mixed-integer linear programming approach is proposed for solving the self-scheduling problem. Uncertainty regarding electricity price is considered through a set of scenarios computed by simulation and scenario-reduction. Thermal units are modelled by variable costs, start-up costs and technical operating constraints, such as: forbidden operating zones, ramp up/down limits and minimum up/down time limits. A requirement on emission allowances to mitigate carbon footprint is modelled by a stochastic constraint. Supply functions for different emission allowance levels are accessed in order to establish the optimal bidding strategy. A case study is presented to illustrate the usefulness and the proficiency of the proposed approach in supporting biding strategies

Preventive Maintenance Scheduling for Multicogeneration Plants with Production Constraints Using Genetic Algorithms

Directory of Open Access Journals (Sweden)

Khaled Alhamad

2015-01-01

Full Text Available This paper describes a method developed to schedule the preventive maintenance tasks of the generation and desalination units in separate and linked cogeneration plants provided that all the necessary maintenance and production constraints are satisfied. The proposed methodology is used to generate two preventing maintenance schedules, one for electricity and the other for distiller. Two types of crossover operators were adopted, 2-point and 4-point. The objective function of the model is to maximize the available number of operational units in each plant. The results obtained were satisfying the problem parameters. However, 4-point slightly produce better solution than 2-point ones for both electricity and water distiller. The performance as well as the effectiveness of the genetic algorithm in solving preventive maintenance scheduling is applied and tested on a real system of 21 units for electricity and 21 units for water. The results presented here show a great potential for utility applications for effective energy management over a time horizon of 52 weeks. The model presented is an effective decision tool that optimizes the solution of the maintenance scheduling problem for cogeneration plants under maintenance and production constraints.

A general treatment of dynamic integrity constraints

NARCIS (Netherlands)

de Brock, EO

This paper introduces a general, set-theoretic model for expressing dynamic integrity constraints, i.e., integrity constraints on the state changes that are allowed in a given state space. In a managerial context, such dynamic integrity constraints can be seen as representations of "real world"

Heuristic Search for Planning with Different Forced Goal-Ordering Constraints

Directory of Open Access Journals (Sweden)

Jiangfeng Luo

2013-01-01

Full Text Available Planning with forced goal-ordering (FGO constraints has been proposed many times over the years, but there are still major difficulties in realizing these FGOs in plan generation. In certain planning domains, all the FGOs exist in the initial state. No matter which approach is adopted to achieve a subgoal, all the subgoals should be achieved in a given sequence from the initial state. Otherwise, the planning may arrive at a deadlock. For some other planning domains, there is no FGO in the initial state. However, FGO may occur during the planning process if certain subgoal is achieved by an inappropriate approach. This paper contributes to illustrate that it is the excludable constraints among the goal achievement operations (GAO of different subgoals that introduce the FGOs into the planning problem, and planning with FGO is still a challenge for the heuristic search based planners. Then, a novel multistep forward search algorithm is proposed which can solve the planning problem with different FGOs efficiently.

An Introduction to 'Creativity Constraints'

DEFF Research Database (Denmark)

Onarheim, Balder; Biskjær, Michael Mose

2013-01-01

Constraints play a vital role as both restrainers and enablers in innovation processes by governing what the creative agent/s can and cannot do, and what the output can and cannot be. Notions of constraints are common in creativity research, but current contributions are highly dispersed due to n...

Market segmentation using perceived constraints

Science.gov (United States)

Jinhee Jun; Gerard Kyle; Andrew Mowen

2008-01-01

We examined the practical utility of segmenting potential visitors to Cleveland Metroparks using their constraint profiles. Our analysis identified three segments based on their scores on the dimensions of constraints: Other priorities--visitors who scored the highest on 'other priorities' dimension; Highly Constrained--visitors who scored relatively high on...

Live animal and meat export value chains for selected areas in Ethiopia: Constraints and opportunities for enhancing meat exports

OpenAIRE

Getachew, Legese; Hailemariam, Teklewold; Dawit, Alemu; Asfaw, Negassa

2008-01-01

The Ethiopian live animal and meat export marketing system is operating in an environment characterized by several constraints that needs the attention and action of the government and other non-governmental development organizations. Despite the reported high livestock population of the country, the major meat and live animal exporters are complaining of shortage of supply and inferior quality of animals (especially shoats). The problem could be because of the constraints in the marketing sy...

Constraint Handling Rules with Binders, Patterns and Generic Quantification

NARCIS (Netherlands)

Serrano, Alejandro; Hage, J.

2017-01-01

Constraint Handling Rules provide descriptions for constraint solvers. However, they fall short when those constraints specify some binding structure, like higher-rank types in a constraint-based type inference algorithm. In this paper, the term syntax of constraints is replaced by λ-tree syntax, in

A d-person Differential Game with State Space Constraints

International Nuclear Information System (INIS)

Ramasubramanian, S.

2007-01-01

We consider a network of d companies (insurance companies, for example) operating under a treaty to diversify risk. Internal and external borrowing are allowed to avert ruin of any member of the network. The amount borrowed to prevent ruin is viewed upon as control. Repayment of these loans entails a control cost in addition to the usual costs. Each company tries to minimize its repayment liability. This leads to a d -person differential game with state space constraints. If the companies are also in possible competition a Nash equilibrium is sought. Otherwise a utopian equilibrium is more appropriate. The corresponding systems of HJB equations and boundary conditions are derived. In the case of Nash equilibrium, the Hamiltonian can be discontinuous; there are d interlinked control problems with state constraints; each value function is a constrained viscosity solution to the appropriate discontinuous HJB equation. Uniqueness does not hold in general in this case. In the case of utopian equilibrium, each value function turns out to be the unique constrained viscosity solution to the appropriate HJB equation. Connection with Skorokhod problem is briefly discussed

Modeling water resources as a constraint in electricity capacity expansion models

Science.gov (United States)

Newmark, R. L.; Macknick, J.; Cohen, S.; Tidwell, V. C.; Woldeyesus, T.; Martinez, A.

2013-12-01

In the United States, the electric power sector is the largest withdrawer of freshwater in the nation. The primary demand for water from the electricity sector is for thermoelectric power plant cooling. Areas likely to see the largest near-term growth in population and energy usage, the Southwest and the Southeast, are also facing freshwater scarcity and have experienced water-related power reliability issues in the past decade. Lack of water may become a barrier for new conventionally-cooled power plants, and alternative cooling systems will impact technology cost and performance. Although water is integral to electricity generation, it has long been neglected as a constraint in future electricity system projections. Assessing the impact of water resource scarcity on energy infrastructure development is critical, both for conventional and renewable energy technologies. Efficiently utilizing all water types, including wastewater and brackish sources, or utilizing dry-cooling technologies, will be essential for transitioning to a low-carbon electricity system. This work provides the first demonstration of a national electric system capacity expansion model that incorporates water resources as a constraint on the current and future U.S. electricity system. The Regional Electricity Deployment System (ReEDS) model was enhanced to represent multiple cooling technology types and limited water resource availability in its optimization of electricity sector capacity expansion to 2050. The ReEDS model has high geographic and temporal resolution, making it a suitable model for incorporating water resources, which are inherently seasonal and watershed-specific. Cooling system technologies were assigned varying costs (capital, operations and maintenance), and performance parameters, reflecting inherent tradeoffs in water impacts and operating characteristics. Water rights supply curves were developed for each of the power balancing regions in ReEDS. Supply curves include costs

Automatic optimization of core loading patterns to maximize cycle energy production within operational constraints

International Nuclear Information System (INIS)

Hobson, G.H.; Turinsky, P.J.

1986-01-01

Computational capability has been developed to automatically determine the core loading pattern which minimizes fuel cycle costs for a pressurized water reactor. Equating fuel cycle cost minimization with core reactivity maximization, the objective is to determine the loading pattern which maximizes core reactivity at end-of-cycle while satisfying the power peaking constraint throughout the cycle and region average discharge burnup limit. The method utilizes a two-dimensional, coarse mesh, finite difference scheme to evaluate core reactivity and fluxes for an initial reference loading pattern as a function of cycle burnup. First order perturbation theory is applied to determine the effects of assembly shuffling on reactivity, power distribution, and end-of-cycle burnup

Resource allocation in shared spectrum access communications for operators with diverse service requirements

Science.gov (United States)

Kibria, Mirza Golam; Villardi, Gabriel Porto; Ishizu, Kentaro; Kojima, Fumihide; Yano, Hiroyuki

2016-12-01

In this paper, we study inter-operator spectrum sharing and intra-operator resource allocation in shared spectrum access communication systems and propose efficient dynamic solutions to address both inter-operator and intra-operator resource allocation optimization problems. For inter-operator spectrum sharing, we present two competent approaches, namely the subcarrier gain-based sharing and fragmentation-based sharing, which carry out fair and flexible allocation of the available shareable spectrum among the operators subject to certain well-defined sharing rules, traffic demands, and channel propagation characteristics. The subcarrier gain-based spectrum sharing scheme has been found to be more efficient in terms of achieved throughput. However, the fragmentation-based sharing is more attractive in terms of computational complexity. For intra-operator resource allocation, we consider resource allocation problem with users' dissimilar service requirements, where the operator supports users with delay constraint and non-delay constraint service requirements, simultaneously. This optimization problem is a mixed-integer non-linear programming problem and non-convex, which is computationally very expensive, and the complexity grows exponentially with the number of integer variables. We propose less-complex and efficient suboptimal solution based on formulating exact linearization, linear approximation, and convexification techniques for the non-linear and/or non-convex objective functions and constraints. Extensive simulation performance analysis has been carried out that validates the efficiency of the proposed solution.

Toward an automaton Constraint for Local Search

Directory of Open Access Journals (Sweden)

Jun He

2009-10-01

Full Text Available We explore the idea of using finite automata to implement new constraints for local search (this is already a successful technique in constraint-based global search. We show how it is possible to maintain incrementally the violations of a constraint and its decision variables from an automaton that describes a ground checker for that constraint. We establish the practicality of our approach idea on real-life personnel rostering problems, and show that it is competitive with the approach of [Pralong, 2007].

Constraint-based Attribute and Interval Planning

Science.gov (United States)

Jonsson, Ari; Frank, Jeremy

2013-01-01

In this paper we describe Constraint-based Attribute and Interval Planning (CAIP), a paradigm for representing and reasoning about plans. The paradigm enables the description of planning domains with time, resources, concurrent activities, mutual exclusions among sets of activities, disjunctive preconditions and conditional effects. We provide a theoretical foundation for the paradigm, based on temporal intervals and attributes. We then show how the plans are naturally expressed by networks of constraints, and show that the process of planning maps directly to dynamic constraint reasoning. In addition, we de ne compatibilities, a compact mechanism for describing planning domains. We describe how this framework can incorporate the use of constraint reasoning technology to improve planning. Finally, we describe EUROPA, an implementation of the CAIP framework.

ESSOPE: Towards S/C operations with reactive schedule planning

Science.gov (United States)

Wheadon, J.

1993-01-01

The ESSOPE is a prototype front-end tool running on a Sun workstation and interfacing to ESOC's MSSS spacecraft control system for the exchange of telecommand requests (to MSSS) and telemetry reports (from MSSS). ESSOPE combines an operations Planner-Scheduler, with a Schedule Execution Control function. Using an internal 'model' of the spacecraft, the Planner generates a schedule based on utilization requests for a variety of payload services by a community of Olympus users, and incorporating certain housekeeping operations. Conflicts based on operational constraints are automatically resolved, by employing one of several available strategies. The schedule is passed to the execution function which drives MSSS to perform it. When the schedule can no longer be met, either because the operator interferes (by delays or changes of requirements), or because ESSOPE has recognized some spacecraft anomalies, the Planner produces a modified schedule maintaining the on-going procedures as far as consistent with the new constraints or requirements.

Advances in Distributed Operations and Mission Activity Planning for Mars Surface Exploration

Science.gov (United States)

Fox, Jason M.; Norris, Jeffrey S.; Powell, Mark W.; Rabe, Kenneth J.; Shams, Khawaja

2006-01-01

A centralized mission activity planning system for any long-term mission, such as the Mars Exploration Rover Mission (MER), is completely infeasible due to budget and geographic constraints. A distributed operations system is key to addressing these constraints; therefore, future system and software engineers must focus on the problem of how to provide a secure, reliable, and distributed mission activity planning system. We will explain how Maestro, the next generation mission activity planning system, with its heavy emphasis on portability and distributed operations has been able to meet these design challenges. MER has been an excellent proving ground for Maestro's new approach to distributed operations. The backend that has been developed for Maestro could benefit many future missions by reducing the cost of centralized operations system architecture.

Constraints on stress-energy perturbations in general relativity

International Nuclear Information System (INIS)

Traschen, J.

1985-01-01

Conditions are found for the existence of integral constraints on stress-energy perturbations in general relativity. The integral constraints can be thought of as a general-relativistic generalization of the conservation of energy and momentum of matter perturbations in special relativity. The constraints are stated in terms of a vector field V, and the Robertson-Walker spacetimes are shown to have such constraint vectors. Although in general V is not a Killing vector, in a vacuum spacetime the constraint vectors are precisely the Killing vectors

On Lifecycle Constraints of Artifact-Centric Workflows

Science.gov (United States)

Kucukoguz, Esra; Su, Jianwen

Data plays a fundamental role in modeling and management of business processes and workflows. Among the recent "data-aware" workflow models, artifact-centric models are particularly interesting. (Business) artifacts are the key data entities that are used in workflows and can reflect both the business logic and the execution states of a running workflow. The notion of artifacts succinctly captures the fluidity aspect of data during workflow executions. However, much of the technical dimension concerning artifacts in workflows is not well understood. In this paper, we study a key concept of an artifact "lifecycle". In particular, we allow declarative specifications/constraints of artifact lifecycle in the spirit of DecSerFlow, and formulate the notion of lifecycle as the set of all possible paths an artifact can navigate through. We investigate two technical problems: (Compliance) does a given workflow (schema) contain only lifecycle allowed by a constraint? And (automated construction) from a given lifecycle specification (constraint), is it possible to construct a "compliant" workflow? The study is based on a new formal variant of artifact-centric workflow model called "ArtiNets" and two classes of lifecycle constraints named "regular" and "counting" constraints. We present a range of technical results concerning compliance and automated construction, including: (1) compliance is decidable when workflow is atomic or constraints are regular, (2) for each constraint, we can always construct a workflow that satisfies the constraint, and (3) sufficient conditions where atomic workflows can be constructed.

Development of monitoring-control methods for heavy remote handling operations in an irradiated environment

Energy Technology Data Exchange (ETDEWEB)

Argouac' h, J R [Alsthom-Atlantique, ACB Nantes (France)

1984-11-01

Heavy remote handling equipment units have benefited from the progress made in robotics, but with certain specific constraints linked to the environment in which they are required to operate. Notably, these constraints impose the exclusive use of electrical techniques.

Evaluation of pig production practices, constraints and opportunities for improvement in smallholder production systems in Kenya.

Science.gov (United States)

Mbuthia, Jackson Mwenda; Rewe, Thomas Odiwuor; Kahi, Alexander Kigunzu

2015-02-01

This study evaluated pig production practices by smallholder farmers in two distinct production systems geared towards addressing their constraints and prospects for improvement. The production systems evaluated were semi-intensive and extensive and differed in remoteness, market access, resource availability and pig production intensity. Data were collected using structured questionnaires where a total of 102 pig farmers were interviewed. Qualitative and quantitative research methods were employed to define the socioeconomic characteristics of the production systems, understanding the different roles that pigs play, marketing systems and constraints to production. In both systems, regular cash income and insurance against emergencies were ranked as the main reasons for rearing pigs. Marketing of pigs was mainly driven by the type of production operation. Finances, feeds and housing were identified as the major constraints to production. The study provides important parameters and identifies constraints important for consideration in design of sustainable production improvement strategies. Feeding challenges can be improved through understanding the composition and proper utilization of local feed resources. Provision of adequate housing would improve the stocking rates and control mating.

Block Pickard Models for Two-Dimensional Constraints

DEFF Research Database (Denmark)

Forchhammer, Søren; Justesen, Jørn

2009-01-01

In Pickard random fields (PRF), the probabilities of finite configurations and the entropy of the field can be calculated explicitly, but only very simple structures can be incorporated into such a field. Given two Markov chains describing a boundary, an algorithm is presented which determines...... for the domino tiling constraint represented by a quaternary alphabet. PRF models are also presented for higher order constraints, including the no isolated bits (n.i.b.) constraint, and a minimum distance 3 constraint by defining super symbols on blocks of binary symbols....

Stochastic User Equilibrium Assignment in Schedule-Based Transit Networks with Capacity Constraints

Directory of Open Access Journals (Sweden)

Wangtu Xu

2012-01-01

Full Text Available This paper proposes a stochastic user equilibrium (SUE assignment model for a schedule-based transit network with capacity constraint. We consider a situation in which passengers do not have the full knowledge about the condition of the network and select paths that minimize a generalized cost function encompassing five components: (1 ride time, which is composed of in-vehicle and waiting times, (2 overload delay, (3 fare, (4 transfer constraints, and (5 departure time difference. We split passenger demands among connections which are the space-time paths between OD pairs of the network. All transit vehicles have a fixed capacity and operate according to some preset timetables. When the capacity constraint of the transit line segment is reached, we show that the Lagrange multipliers of the mathematical programming problem are equivalent to the equilibrium passenger overload delay in the congested transit network. The proposed model can simultaneously predict how passengers choose their transit vehicles to minimize their travel costs and estimate the associated costs in a schedule-based congested transit network. A numerical example is used to illustrate the performance of the proposed model.

Interim guidelines on performance constraints for nuclear waste disposal in crystalline rock

International Nuclear Information System (INIS)

1984-01-01

Performance constraint guidelines have been developed for geologic disposal of nuclear waste in crystalline rock. The approach taken in defining these guidelines was to consider the thermal, thermomechanical, and thermochemical behavior for three regions (very-near field, near field, and far field) of the repository during three time periods (operational, containment, and isolation) associated with the disposal system. Limits are proposed to ensure compliance with the current repository criteria proposed by the United States Nuclear Regulatory Commission (NRC) concerning repository siting and performance assessment. These criteria are: Substantial containment of all radionuclides within the waste package for a period of time between 300 and 1000 years after emplacement. Release rate after loss of containment of one part in 100,000 annually per radionuclide based on the nuclides inventory when the waste package is breached, and in situ ground-water transit time of 1000 years from the repository horizon to the accessible environment, compliance with the performance constraint guidelines presented herein will be required to ensure that the final repository design is in compliance with NRC criteria. The constraint guidelines have also been developed to satisfy the requirement for technical conservatism. 40 refs., 14 figs., 4 tabs

Lithium-Ion Battery Online Rapid State-of-Power Estimation under Multiple Constraints

Directory of Open Access Journals (Sweden)

Shun Xiang

2018-01-01

Full Text Available The paper aims to realize a rapid online estimation of the state-of-power (SOP with multiple constraints of a lithium-ion battery. Firstly, based on the improved first-order resistance-capacitance (RC model with one-state hysteresis, a linear state-space battery model is built; then, using the dual extended Kalman filtering (DEKF method, the battery parameters and states, including open-circuit voltage (OCV, are estimated. Secondly, by employing the estimated OCV as the observed value to build the second dual Kalman filters, the battery SOC is estimated. Thirdly, a novel rapid-calculating peak power/SOP method with multiple constraints is proposed in which, according to the bisection judgment method, the battery’s peak state is determined; then, one or two instantaneous peak powers are used to determine the peak power during T seconds. In addition, in the battery operating process, the actual constraint that the battery is under is analyzed specifically. Finally, three simplified versions of the Federal Urban Driving Schedule (SFUDS with inserted pulse experiments are conducted to verify the effectiveness and accuracy of the proposed online SOP estimation method.

A decomposition method for network-constrained unit commitment with AC power flow constraints

International Nuclear Information System (INIS)

Bai, Yang; Zhong, Haiwang; Xia, Qing; Kang, Chongqing; Xie, Le

2015-01-01

To meet the increasingly high requirement of smart grid operations, considering AC power flow constraints in the NCUC (network-constrained unit commitment) is of great significance in terms of both security and economy. This paper proposes a decomposition method to solve NCUC with AC power flow constraints. With conic approximations of the AC power flow equations, the master problem is formulated as a MISOCP (mixed integer second-order cone programming) model. The key advantage of this model is that the active power and reactive power are co-optimised, and the transmission losses are considered. With the AC optimal power flow model, the AC feasibility of the UC result of the master problem is checked in subproblems. If infeasibility is detected, feedback constraints are generated based on the sensitivity of bus voltages to a change in the unit reactive power generation. They are then introduced into the master problem in the next iteration until all AC violations are eliminated. A 6-bus system, a modified IEEE 30-bus system and the IEEE 118-bus system are used to validate the performance of the proposed method, which provides a satisfactory solution with approximately 44-fold greater computational efficiency. - Highlights: • A decomposition method is proposed to solve the NCUC with AC power flow constraints • The master problem considers active power, reactive power and transmission losses. • OPF-based subproblems check the AC feasibility using parallel computing techniques. • An effective feedback constraint interacts between the master problem and subproblem. • Computational efficiency is significantly improved with satisfactory accuracy

On distributed parameter control systems in the abnormal case and in the case of nonoperator equality constraints

Directory of Open Access Journals (Sweden)

Urszula Ledzewicz

1993-01-01

Full Text Available In this paper, a general distributed parameter control problem in Banach spaces with integral cost functional and with given initial and terminal data is considered. An extension of the Dubovitskii-Milyutin method to the case of nonregular operator equality constraints, based on Avakov's generalization of the Lusternik theorem, is presented. This result is applied to obtain an extension of the Extremum Principle for the case of abnormal optimal control problems. Then a version of this problem with nonoperator equality constraints is discussed and the Extremum Principle for this problem is presented.

Operator spin foam models

International Nuclear Information System (INIS)

Bahr, Benjamin; Hellmann, Frank; Kaminski, Wojciech; Kisielowski, Marcin; Lewandowski, Jerzy

2011-01-01

The goal of this paper is to introduce a systematic approach to spin foams. We define operator spin foams, that is foams labelled by group representations and operators, as our main tool. A set of moves we define in the set of the operator spin foams (among other operations) allows us to split the faces and the edges of the foams. We assign to each operator spin foam a contracted operator, by using the contractions at the vertices and suitably adjusted face amplitudes. The emergence of the face amplitudes is the consequence of assuming the invariance of the contracted operator with respect to the moves. Next, we define spin foam models and consider the class of models assumed to be symmetric with respect to the moves we have introduced, and assuming their partition functions (state sums) are defined by the contracted operators. Briefly speaking, those operator spin foam models are invariant with respect to the cellular decomposition, and are sensitive only to the topology and colouring of the foam. Imposing an extra symmetry leads to a family we call natural operator spin foam models. This symmetry, combined with assumed invariance with respect to the edge splitting move, determines a complete characterization of a general natural model. It can be obtained by applying arbitrary (quantum) constraints on an arbitrary BF spin foam model. In particular, imposing suitable constraints on a spin(4) BF spin foam model is exactly the way we tend to view 4D quantum gravity, starting with the BC model and continuing with the Engle-Pereira-Rovelli-Livine (EPRL) or Freidel-Krasnov (FK) models. That makes our framework directly applicable to those models. Specifically, our operator spin foam framework can be translated into the language of spin foams and partition functions. Among our natural spin foam models there are the BF spin foam model, the BC model, and a model corresponding to the EPRL intertwiners. Our operator spin foam framework can also be used for more general spin

Revisiting the simplicity constraints and coherent intertwiners

International Nuclear Information System (INIS)

Dupuis, Maite; Livine, Etera R

2011-01-01

In the context of loop quantum gravity and spinfoam models, the simplicity constraints are essential in that they allow one to write general relativity as a constrained topological BF theory. In this work, we apply the recently developed U(N) framework for SU(2) intertwiners to the issue of imposing the simplicity constraints to spin network states. More particularly, we focus on solving on individual intertwiners in the 4D Euclidean theory. We review the standard way of solving the simplicity constraints using coherent intertwiners and we explain how these fit within the U(N) framework. Then we show how these constraints can be written as a closed u(N) algebra and we propose a set of U(N) coherent states that solves all the simplicity constraints weakly for an arbitrary Immirzi parameter.

Task-oriented structural design of manipulators based on operability evaluation

International Nuclear Information System (INIS)

Kotosaka, Shin-ya; Asama, Hajime; Takata, Shozo; Hiraoka, Hiroyuki; Kohda, Takehisa; Matsumoto, Akihiro; Endo, Isao.

1995-01-01

In this paper, a new method for designing the structure of manipulators based on evaluation of their adaptability to tasks is proposed. In the method, task directions are classified into three kinds of direction; operational direction, constrained direction and free direction. On each direction, condition of constraints by task environment is represented. The tasks are represented by a set of direction and condition of constraints. A new criterion, operability, is defined to quantify adaptability of manipulator to tasks, taking account of mobility in operational directions and immobility in constrained directions. The mobility and immobility is calculated based on the Jacobian matrix of manipulator. The operability evaluation method is implemented, and applied to structural design of manipulators, in which link parameters are optimized by the genetic algorithm. This system can derive suitable structure of manipulator to various tasks. The effectiveness of the system is shown concerning examples of welding tasks. (author)

The Ambiguous Role of Constraints in Creativity

DEFF Research Database (Denmark)

Biskjær, Michael Mose; Onarheim, Balder; Wiltschnig, Stefan

2011-01-01

The relationship between creativity and constraints is often described in the literature either in rather imprecise, general concepts or in relation to very specific domains. Cross-domain and cross-disciplinary takes on how the handling of constraints influences creative activities are rare. In t......-disciplinary research into the ambiguous role of constraints in creativity....

Fixed Costs and Hours Constraints

Science.gov (United States)

Johnson, William R.

2011-01-01

Hours constraints are typically identified by worker responses to questions asking whether they would prefer a job with more hours and more pay or fewer hours and less pay. Because jobs with different hours but the same rate of pay may be infeasible when there are fixed costs of employment or mandatory overtime premia, the constraint in those…

Future Cosmological Constraints From Fast Radio Bursts

Science.gov (United States)

Walters, Anthony; Weltman, Amanda; Gaensler, B. M.; Ma, Yin-Zhe; Witzemann, Amadeus

2018-03-01

We consider the possible observation of fast radio bursts (FRBs) with planned future radio telescopes, and investigate how well the dispersions and redshifts of these signals might constrain cosmological parameters. We construct mock catalogs of FRB dispersion measure (DM) data and employ Markov Chain Monte Carlo analysis, with which we forecast and compare with existing constraints in the flat ΛCDM model, as well as some popular extensions that include dark energy equation of state and curvature parameters. We find that the scatter in DM observations caused by inhomogeneities in the intergalactic medium (IGM) poses a big challenge to the utility of FRBs as a cosmic probe. Only in the most optimistic case, with a high number of events and low IGM variance, do FRBs aid in improving current constraints. In particular, when FRBs are combined with CMB+BAO+SNe+H 0 data, we find the biggest improvement comes in the {{{Ω }}}{{b}}{h}2 constraint. Also, we find that the dark energy equation of state is poorly constrained, while the constraint on the curvature parameter, Ω k , shows some improvement when combined with current constraints. When FRBs are combined with future baryon acoustic oscillation (BAO) data from 21 cm Intensity Mapping, we find little improvement over the constraints from BAOs alone. However, the inclusion of FRBs introduces an additional parameter constraint, {{{Ω }}}{{b}}{h}2, which turns out to be comparable to existing constraints. This suggests that FRBs provide valuable information about the cosmological baryon density in the intermediate redshift universe, independent of high-redshift CMB data.

Faddeev-Jackiw quantization and constraints

International Nuclear Information System (INIS)

Barcelos-Neto, J.; Wotzasek, C.

1992-01-01

In a recent Letter, Faddeev and Jackiw have shown that the reduction of constrained systems into its canonical, first-order form, can bring some new insight into the research of this field. For sympletic manifolds the geometrical structure, called Dirac or generalized bracket, is obtained directly from the inverse of the nonsingular sympletic two-form matrix. In the cases of nonsympletic manifolds, this two-form is degenerated and cannot be inverted to provide the generalized brackets. This singular behavior of the sympletic matrix is indicative of the presence of constraints that have to be carefully considered to yield to consistent results. One has two possible routes to treat this problem: Dirac has taught us how to implement the constraints into the potential part (Hamiltonian) of the canonical Lagrangian, leading to the well-known Dirac brackets, which are consistent with the constraints and can be mapped into quantum commutators (modulo ordering terms). The second route, suggested by Faddeev and Jackiw, and followed in this paper, is to implement the constraints directly into the canonical part of the first order Lagrangian, using the fact that the consistence condition for the stability of the constrained manifold is linear in the time derivative. This algorithm may lead to an invertible two-form sympletic matrix from where the Dirac brackets are readily obtained. This algorithm is used in this paper to investigate some aspects of the quantization of constrained systems with first- and second-class constraints in the sympletic approach

Liquidity Constraints and Fiscal Stabilization Policy

DEFF Research Database (Denmark)

Kristoffersen, Mark Strøm

It is often claimed that the presence of liquidity constrained households enhances the need for and the effects of fi…scal stabilization policies. This paper studies this in a model of a small open economy with liquidity constrained households. The results show that the consequences of liquidity...... constraints are more complex than previously thought: The optimal stabilization policy in case of productivity shocks is independent of the liquidity constraints, and the presence of liquidity constraints tends to reduce the need for an active policy stabilizing productivity shocks....

LHC constraints on gauge boson couplings to dark matter

CERN Document Server

Crivellin, Andreas; Hibbs, Anthony

2015-01-01

Collider searches for energetic particles recoiling against missing transverse energy allow to place strong bounds on the interactions between dark matter (DM) and standard model particles. In this article we update and extend LHC constraints on effective dimension-7 operators involving DM and electroweak gauge bosons. A concise comparison of the sensitivity of the mono-photon, mono-W, mono-Z, mono-W/Z, invisible Higgs-boson decays in the vector boson fusion mode and the mono-jet channel is presented. Depending on the parameter choices, either the mono-photon or the mono-jet data provide the most stringent bounds at the moment. We furthermore explore the potential of improving the current 8 TeV limits at 14 TeV. Future strategies capable of disentangling the effects of the different effective operators involving electroweak gauge bosons are discussed as well.

Review of Minimal Flavor Constraints for Technicolor

DEFF Research Database (Denmark)

S. Fukano, Hidenori; Sannino, Francesco

2010-01-01

We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self-coupling and mas......We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self...

Research on Bifurcation and Chaos in a Dynamic Mixed Game System with Oligopolies Under Carbon Emission Constraint

Science.gov (United States)

Ma, Junhai; Yang, Wenhui; Lou, Wandong

This paper establishes an oligopolistic game model under the carbon emission reduction constraint and investigates its complex characteristics like bifurcation and chaos. Two oligopolistic manufacturers comprise three mixed game models, aiming to explore the variation in the status of operating system as per the upgrading of benchmark reward-penalty mechanism. Firstly, we set up these basic models that are respectively distinguished with carbon emission quantity and study these models using different game methods. Then, we concentrate on one typical game model to further study the dynamic complexity of variations in the system status, through 2D bifurcation diagrams and 4D parameter adjustment features based on the bounded rationality scheme for price, and the adaptive scheme for carbon emission. The results show that the carbon emission constraint has significant influence on the status variation of two-oligopolistic game operating systems no matter whether it is stable or chaotic. Besides, the new carbon emission regulation meets government supervision target and achieves the goal of being environment friendly by motivating the system to operate with lower carbon emission.

Relaxations of semiring constraint satisfaction problems

CSIR Research Space (South Africa)

Leenen, L

2007-03-01

Full Text Available The Semiring Constraint Satisfaction Problem (SCSP) framework is a popular approach for the representation of partial constraint satisfaction problems. In this framework preferences can be associated with tuples of values of the variable domains...

Solar system constraints on disformal gravity theories

International Nuclear Information System (INIS)

Ip, Hiu Yan; Schmidt, Fabian; Sakstein, Jeremy

2015-01-01

Disformal theories of gravity are scalar-tensor theories where the scalar couples derivatively to matter via the Jordan frame metric. These models have recently attracted interest in the cosmological context since they admit accelerating solutions. We derive the solution for a static isolated mass in generic disformal gravity theories and transform it into the parameterised post-Newtonian form. This allows us to investigate constraints placed on such theories by local tests of gravity. The tightest constraints come from preferred-frame effects due to the motion of the Solar System with respect to the evolving cosmological background field. The constraints we obtain improve upon the previous solar system constraints by two orders of magnitude, and constrain the scale of the disformal coupling for generic models to ℳ ∼> 100 eV. These constraints render all disformal effects irrelevant for cosmology

A Hybrid Method for Modeling and Solving Supply Chain Optimization Problems with Soft and Logical Constraints

Directory of Open Access Journals (Sweden)

Paweł Sitek

2016-01-01

Full Text Available This paper presents a hybrid method for modeling and solving supply chain optimization problems with soft, hard, and logical constraints. Ability to implement soft and logical constraints is a very important functionality for supply chain optimization models. Such constraints are particularly useful for modeling problems resulting from commercial agreements, contracts, competition, technology, safety, and environmental conditions. Two programming and solving environments, mathematical programming (MP and constraint logic programming (CLP, were combined in the hybrid method. This integration, hybridization, and the adequate multidimensional transformation of the problem (as a presolving method helped to substantially reduce the search space of combinatorial models for supply chain optimization problems. The operation research MP and declarative CLP, where constraints are modeled in different ways and different solving procedures are implemented, were linked together to use the strengths of both. This approach is particularly important for the decision and combinatorial optimization models with the objective function and constraints, there are many decision variables, and these are summed (common in manufacturing, supply chain management, project management, and logistic problems. The ECLiPSe system with Eplex library was proposed to implement a hybrid method. Additionally, the proposed hybrid transformed model is compared with the MILP-Mixed Integer Linear Programming model on the same data instances. For illustrative models, its use allowed finding optimal solutions eight to one hundred times faster and reducing the size of the combinatorial problem to a significant extent.

Study of low energy thermal constraints for a copper-plated niobium structure carried out by thermal projection

International Nuclear Information System (INIS)

Gassot, H.; Durante, M.; Thiebault, A.; Vernay, E.

1999-06-01

In the framework of T.T.F. (Tesla Test Facility), the international collaboration on research and development of superconducting cavities, a study of a new method of manufacturing cavities was launched, which consists in deposing a metal (copper) or an alloy by thermal projection on niobium cavities in order to stiffen them. Analytical and numerical calculations showed that when cooled this bi-material cavities behave very differently in comparison with classical pure niobium cavities and strong thermal constraints do occur in niobium as well as in copper. These strong constraints may have important consequences upon the functioning of superconducting cavities. In addition these constraints may induce in time cracks in materials and interfaces. In this paper an experiment for measuring constraints at the temperature of cavity operation, i.e., at the liquid helium temperature, is proposed in order to compare the measured constraints with the calculated constraints. The sample studied has a cylindrical shape, rather representative for the geometrical shape of cavities, but easier to handle than a prototype cavity. The experimental approach consists in carrying out two deformation measurements. The first one, is done on single material sample (niobium and copper) to establish the laws of compensation of the constraint gauges as a function of temperature. The other measurement establishes the global deformations of a bi-metallic tube (Nb-Cu) when the interior surface (niobium) and the external surface (porous copper) of the tube are cooled. From these deformation data the thermal constraints of the bi-metallic tube at low temperature have been derived. The implementation of the entire setup of the methods of measuring the constraints at low temperature constitutes a new development in the field of superconducting cavities. The experiments have also indicated certain further developments which should be achieved if the plastic deformations induced by the freezing regime

Observational constraints on interstellar chemistry

International Nuclear Information System (INIS)

Winnewisser, G.

1984-01-01

The author points out presently existing observational constraints in the detection of interstellar molecular species and the limits they may cast on our knowledge of interstellar chemistry. The constraints which arise from the molecular side are summarised and some technical difficulties encountered in detecting new species are discussed. Some implications for our understanding of molecular formation processes are considered. (Auth.)

Expressing Model Constraints Visually with VMQL

DEFF Research Database (Denmark)

Störrle, Harald

2011-01-01

) for specifying constraints on UML models. We examine VMQL's usability by controlled experiments and its expressiveness by a representative sample. We conclude that VMQL is less expressive than OCL, although expressive enough for most of the constraints in the sample. In terms of usability, however, VMQL......OCL is the de facto standard language for expressing constraints and queries on UML models. However, OCL expressions are very difficult to create, understand, and maintain, even with the sophisticated tool support now available. In this paper, we propose to use the Visual Model Query Language (VMQL...

Implicit Motives and Men's Perceived Constraint in Fatherhood.

Science.gov (United States)

Ruppen, Jessica; Waldvogel, Patricia; Ehlert, Ulrike

2016-01-01

Research shows that implicit motives influence social relationships. However, little is known about their role in fatherhood and, particularly, how men experience their paternal role. Therefore, this study examined the association of implicit motives and fathers' perceived constraint due to fatherhood. Furthermore, we explored their relation to fathers' life satisfaction. Participants were fathers with biological children ( N = 276). They were asked to write picture stories, which were then coded for implicit affiliation and power motives. Perceived constraint and life satisfaction were assessed on a visual analog scale. A higher implicit need for affiliation was significantly associated with lower perceived constraint, whereas the implicit need for power had the opposite effect. Perceived constraint had a negative influence on life satisfaction. Structural equation modeling revealed significant indirect effects of implicit affiliation and power motives on life satisfaction mediated by perceived constraint. Our findings indicate that men with a higher implicit need for affiliation experience less constraint due to fatherhood, resulting in higher life satisfaction. The implicit need for power, however, results in more perceived constraint and is related to decreased life satisfaction.

On proving confluence modulo equivalence for Constraint Handling Rules

DEFF Research Database (Denmark)

Christiansen, Henning; Kirkeby, Maja Hanne

2017-01-01

-logical built-in predicates such as var/1 and incomplete ones such as is/2, that are ignored in previous work on confluence. To this end, a new operational semantics for CHR is developed which includes such predicates. In addition, this semantics differs from earlier approaches by its simplicity without loss......Previous results on proving confluence for Constraint Handling Rules are extended in two ways in order to allow a larger and more realistic class of CHR programs to be considered confluent. Firstly, we introduce the relaxed notion of confluence modulo equivalence into the context of CHR: while...

Initial Concept of Operations for Full Management by Trajectory

Science.gov (United States)

Fernandes, Alicia D.; Atkins, Steve; Leiden, Ken; Kaler, Curt; Evans, Mark; Bell, Alan; Kilbourne, Todd; Jackson, Michael

2017-01-01

This document describes Management by Trajectory (MBT), a concept for future air traffic management (ATM) in which flights are assigned four-dimensional trajectories (4DTs) through a negotiation process between the Federal Aviation Administration (FAA) and flight operators that respects the flight operator's goals while complying with National Airspace System (NAS) constraints.

Operation Enduring Freedom: Institutional Constraints, Alliance Commitments, and the Power Capabilities of Counterterrorism

Directory of Open Access Journals (Sweden)

Kyle T Kattelman

2014-06-01

Full Text Available 'What prompted states to participate in the War on Terror? Conventional wisdom concludes that the endeavor is an unpopular exercise in US imperialism, yet this argument is juxtaposed with the overwhelming amount of international support in its initial stages. Additionally, while there is a great depth and breadth of information on aggregate terrorist attacks and their theoretical motivation, there is relatively little with regards to counterterrorist behavior. This study represents the first of its kind to examine from a global perspective the counterterrorist behavior of states by linking it to the conflict theories of general and immediate deterrence. The results will show how democratic characteristics inhibit military commitment while alliance obligations act as an outside constraint that engenders preemptive behavior. However, once committed militarily, state capabilities are the main influence on the level of preemptive action applied. This analysis supports the utilization of traditional conflict theories when examining state counterterrorist behavior.' ' '

Chantey Castings: A Hands-On Simulation to Teach Constraint Management and Demand-Driven Supply Chain Approaches

Science.gov (United States)

Grandzol, Christian J.; Grandzol, John R.

2018-01-01

Supply chain design and constraint management are widely-adopted techniques in industry, necessitating that operations and supply chain educators teach these topics in ways that enhance student learning and retention, optimize resource utilization (especially time), and maximize student interest. The Chantey Castings Simulation provides a platform…

On relaxing the Mangasarian-Fromovitz constraint qualification

Czech Academy of Sciences Publication Activity Database

Kruger, A.Y.; Minchenko, L.; Outrata, Jiří

2014-01-01

Roč. 18, č. 1 (2014), s. 171-189 ISSN 1385-1292 R&D Projects: GA ČR GAP402/12/1309 Institutional support: RVO:67985556 Keywords : Nonlinear programming * Regularity conditions * Constraint qualifications * Lagrange multipliers * Mangasarian–Fromovitz constraint qualification * Constant rank constraint qualification Subject RIV: BA - General Mathematics Impact factor: 0.679, year: 2014 http://library.utia.cas.cz/separaty/2014/MTR/outrata-0426110.pdf

Constraint programming for modelling and solving modal satisfiability

NARCIS (Netherlands)

Brand, S.; Gennari, R.; de Rijke, M.

2003-01-01

We explore to what extent and how efficiently constraint programmingcan be used in the context of automated reasoning for modal logics. We encode modal satisfiability problems as constraint satisfactionproblems with non-boolean domains, together with suitable constraints.Experiments show that the

A Method for Optimal Load Dispatch of a Multi-zone Power System with Zonal Exchange Constraints

Science.gov (United States)

Hazarika, Durlav; Das, Ranjay

2018-04-01

This paper presented a method for economic generation scheduling of a multi-zone power system having inter zonal operational constraints. For this purpose, the generator rescheduling for a multi area power system having inter zonal operational constraints has been represented as a two step optimal generation scheduling problem. At first, the optimal generation scheduling has been carried out for the zone having surplus or deficient generation with proper spinning reserve using co-ordination equation. The power exchange required for the deficit zones and zones having no generation are estimated based on load demand and generation for the zone. The incremental transmission loss formulas for the transmission lines participating in the power transfer process among the zones are formulated. Using these, incremental transmission loss expression in co-ordination equation, the optimal generation scheduling for the zonal exchange has been determined. Simulation is carried out on IEEE 118 bus test system to examine the applicability and validity of the method.

Cosmological constraints on Brans-Dicke theory.

Science.gov (United States)

Avilez, A; Skordis, C

2014-07-04

We report strong cosmological constraints on the Brans-Dicke (BD) theory of gravity using cosmic microwave background data from Planck. We consider two types of models. First, the initial condition of the scalar field is fixed to give the same effective gravitational strength Geff today as the one measured on Earth, GN. In this case, the BD parameter ω is constrained to ω>692 at the 99% confidence level, an order of magnitude improvement over previous constraints. In the second type, the initial condition for the scalar is a free parameter leading to a somewhat stronger constraint of ω>890, while Geff is constrained to 0.981theory and are valid for any Horndeski theory, the most general second-order scalar-tensor theory, which approximates the BD theory on cosmological scales. In this sense, our constraints place strong limits on possible modifications of gravity that might explain cosmic acceleration.

Non-standard constraints within In-Core Fuel Management

Energy Technology Data Exchange (ETDEWEB)

Maldonado, G.I. [University of Cincinnati, P.O. Box 210072, Cincinnati, OH 45221-0072 (United States); Torres, C. [Comision Federal de Electricidad, Gestion de Combustible, Mexico, D.F. (Mexico); Marrote, G.N.; Ruiz U, V. [Global Nuclear Fuel, Americas, LLC, PO Box 780, M/C A16, Wilmington, NC28402 (United States)]. e-mail: Ivan.Maldonado@uc.edu

2004-07-01

Recent advancements in the area of nuclear fuel management optimization have been considerable and widespread. Therefore, it is not surprising that the design of today's nuclear fuel reloads can be a highly automated process that is often accompanied by sophisticated optimization software and graphical user interfaces to assist core designers. Most typically, among other objectives, optimization software seeks to maximize the energy efficiency of a fuel cycle while satisfying a variety of safety, operational, and regulatory constraints. Concurrently, the general industry trend continues to be one of pursuing higher generating capacity (i.e., power up-rates) alongside cycle length extensions. As these increasingly invaluable software tools and ambitious performance goals are pursued in unison, more aggressive core designs ultimately emerge that effectively minimize the margins to limits and, in some cases, may turn out less forgiving or accommodating to changes in underlying key assumptions. The purpose of this article is to highlight a few 'non-standard', though common constraints that can affect a BWR core design but which are often difficult, if not impossible, to implement into an automated setting. In a way, this article indirectly emphasizes the unique and irreplaceable role of the experienced designer in light of 'real life' situations. (Author)

Non-standard constraints within In-Core Fuel Management

International Nuclear Information System (INIS)

Maldonado, G.I.; Torres, C.; Marrote, G.N.; Ruiz U, V.

2004-01-01

Recent advancements in the area of nuclear fuel management optimization have been considerable and widespread. Therefore, it is not surprising that the design of today's nuclear fuel reloads can be a highly automated process that is often accompanied by sophisticated optimization software and graphical user interfaces to assist core designers. Most typically, among other objectives, optimization software seeks to maximize the energy efficiency of a fuel cycle while satisfying a variety of safety, operational, and regulatory constraints. Concurrently, the general industry trend continues to be one of pursuing higher generating capacity (i.e., power up-rates) alongside cycle length extensions. As these increasingly invaluable software tools and ambitious performance goals are pursued in unison, more aggressive core designs ultimately emerge that effectively minimize the margins to limits and, in some cases, may turn out less forgiving or accommodating to changes in underlying key assumptions. The purpose of this article is to highlight a few 'non-standard', though common constraints that can affect a BWR core design but which are often difficult, if not impossible, to implement into an automated setting. In a way, this article indirectly emphasizes the unique and irreplaceable role of the experienced designer in light of 'real life' situations. (Author)

A note on the BFV-BRST operator quantization method

International Nuclear Information System (INIS)

Dayi, O.F.

1988-03-01

The BFV-BRST operator quantization method is applied to massive, abelian (Yang-Mills) theory which has only second class constraints. A nilpotent BFV-BRST-charge is derived and used to define a unitarizing hamiltonian. Unphysical degrees of freedom can be eliminated either in a canonical gauge or in a relativistic one. In the latter gauge this is a general feature (at least locally) of the BFV-BRST quantization of the systems with irreducible constraints. (author). 23 refs

Determining the Probability of Violating Upper-Level Wind Constraints for the Launch of Minuteman Ill Ballistic Missiles At Vandenberg Air Force Base

Science.gov (United States)

Shafer, Jaclyn A.; Brock, Tyler M.

2013-01-01

The 30th Operational Support Squadron Weather Flight (30 OSSWF) provides comprehensive weather services to the space program at Vandenberg Air Force Base (VAFB) in California. One of their responsibilities is to monitor upper-level winds to ensure safe launch operations of the Minuteman Ill ballistic missile. The 30 OSSWF requested the Applied Meteorology Unit (AMU) analyze VAFB sounding data to determine the probability of violating (PoV) upper-level thresholds for wind speed and shear constraints specific to this launch vehicle, and to develop a graphical user interface (GUI) that will calculate the PoV of each constraint on the day of launch. The AMU suggested also including forecast sounding data from the Rapid Refresh (RAP) model. This would provide further insight for the launch weather officers (LWOs) when determining if a wind constraint violation will occur over the next few hours, and help to improve the overall upper winds forecast on launch day.

A Temporal Concurrent Constraint Programming Calculus

DEFF Research Database (Denmark)

Palamidessi, Catuscia; Valencia Posso, Frank Darwin

2001-01-01

The tcc model is a formalism for reactive concurrent constraint programming. In this paper we propose a model of temporal concurrent constraint programming which adds to tcc the capability of modeling asynchronous and non-deterministic timed behavior. We call this tcc extension the ntcc calculus...

Toward making the constraint hypersurface an attractor in free evolution

International Nuclear Information System (INIS)

Fiske, David R.

2004-01-01

When constructing numerical solutions to systems of evolution equations subject to a constraint, one must decide what role the constraint equations will play in the evolution system. In one popular choice, known as free evolution, a simulation is treated as a Cauchy problem, with the initial data constructed to satisfy the constraint equations. This initial data are then evolved via the evolution equations with no further enforcement of the constraint equations. The evolution, however, via the discretized evolution equations introduce constraint violating modes at the level of truncation error, and these constraint violating modes will behave in a formalism dependent way. This paper presents a generic method for incorporating the constraint equations into the evolution equations so that the off-constraint dynamics are biased toward the constraint satisfying solutions

The influence of end constraints on smooth pipe bends

International Nuclear Information System (INIS)

Thomson, G.; Spence, J.

1981-01-01

With present trends in the power industries towards higher operating temperatures and pressures, problems associated with the design and safety assessment of pipework systems have become increasingly complex. Within such systems, the importance of smooth pipe bends is well established. The work which will be presented will attempt to clarify the situation and unify the results. An analytical solution of the problem of a linear elastic smooth pipe bend with end constraints under in-plane bending will be presented. The analysis will deal with constraints in the form of flanged tangents of any length. The analysis employs the theorem of minimum total potential energy with suitable kinematically admissible displacements in the form of Fourier series. The integrations and minimisation were performed numerically, thereby permitting the removal of several of the assumptions made by previous authors. Typical results for flexibilities will be given along with comparisons with other works. The differences in some earlier theory are clarified and other more recent work using different solution techniques is substantiated. The bend behaviour is shown to be strongly influenced by the pipe bend parameter, the bend angle, the tangent pipe length and the bend/cross-sectional radius ratio. (orig./GL)

Judgement of Design Scheme Based on Flexible Constraint in ICAD

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

The conception of flexible constraint is proposed in the paper. The solution of flexible constraint is in special range, and maybe different in different instances of same design scheme. The paper emphasis on how to evaluate and optimize a design scheme with flexible constraints based on the satisfaction degree function defined on flexible constraints. The conception of flexible constraint is used to solve constraint conflict and design optimization in complicated constraint-based assembly design by the PFM parametrization assembly design system. An instance of gear-box design is used for verifying optimization method.

A comparison of debt and primary-deficit constraints

NARCIS (Netherlands)

Ribeiro, M.P.; Beetsma, R.; Schabert, A.

2008-01-01

This paper compares constraints on the public debt with constraints on the primary deficit. The analysis takes into account how an optimizing government reacts to the different constraints when deciding on a spending and borrowing plan. We find that the economy behaves similarly under both

Prototype high voltage bushing: Configuration to its operational demonstration

Energy Technology Data Exchange (ETDEWEB)

Shah, Sejal, E-mail: sshah@iter-india.org [ITER-India, Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Sharma, D. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Parmar, D.; Tyagi, H.; Joshi, K.; Shishangiya, H.; Bandyopadhyay, M.; Rotti, C.; Chakraborty, A. [ITER-India, Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2016-12-15

High Voltage Bushing (HVB) is the key component of Diagnostic Neutral Beam (DNB) system of ITER as it provides access to high voltage electrical, hydraulic, gas and diagnostic feedlines to the beam source with isolation from grounded vessel. HVB also provides primary vacuum confinement for the DNB system. Being Safety Important Class (SIC) component of ITER, it involves several configurational, technological and operational challenges. To ensure its operational performance & reliability, particularly electrostatic behavior, half scale down Prototype High Voltage Bushing (PHVB) is designed considering same design criteria of DNB HVB. Design optimization has been carried out followed by finite element (FE) analysis to obtain DNB HVB equivalent electric stress on different parts of PHVB, taking into account all design, manufacturing & space constraints. PHVB was tested up to 60 kV without breakdown, which validates its design for the envisaged operation of 50 kV DC. This paper presents the design of PHVB, FEA validation, manufacturing constraints, experimental layout with interfacing auxiliary systems and operational results related to functional performance.

Application of a methodology based on the Theory of Constraints in the sector of tourism services

Directory of Open Access Journals (Sweden)

Reyner Pérez Campdesuñer

2017-04-01

Full Text Available Purpose: The objective of the research was aimed at achieving the implementation of the theory of constraints on the operating conditions of a hotel, which differs by its characteristics of traditional processes that have applied this method, from the great heterogeneity of resources needed to meet the demand of customers. Design/methodology/approach: To achieve this purpose, a method of generating conversion equations that allowed to express all the resources of the organization under study depending on the number of customers to serve facilitating comparison between different resources and estimated demand through techniques developed traditional forecasting, these features were integrated into the classical methodology of theory of constraints. Findings: The application of tools designed for hospitality organizations allowed to demonstrate the applicability of the theory of constraints on entities under conditions different from the usual, develop a set of conversion equations of different resources facilitating comparison with demand and consequently achieve improve levels of efficiency and effectiveness of the organization. Originality/value: The originality of the research is summarized in the application of the theory of constraints in a very different from the usual conditions, covering 100% of the processes and resources in hospitality organizations.

Two non-parametric methods for derivation of constraints from radiotherapy dose–histogram data

International Nuclear Information System (INIS)

Ebert, M A; Kennedy, A; Joseph, D J; Gulliford, S L; Buettner, F; Foo, K; Haworth, A; Denham, J W

2014-01-01

Dose constraints based on histograms provide a convenient and widely-used method for informing and guiding radiotherapy treatment planning. Methods of derivation of such constraints are often poorly described. Two non-parametric methods for derivation of constraints are described and investigated in the context of determination of dose-specific cut-points—values of the free parameter (e.g., percentage volume of the irradiated organ) which best reflect resulting changes in complication incidence. A method based on receiver operating characteristic (ROC) analysis and one based on a maximally-selected standardized rank sum are described and compared using rectal toxicity data from a prostate radiotherapy trial. Multiple test corrections are applied using a free step-down resampling algorithm, which accounts for the large number of tests undertaken to search for optimal cut-points and the inherent correlation between dose–histogram points. Both methods provide consistent significant cut-point values, with the rank sum method displaying some sensitivity to the underlying data. The ROC method is simple to implement and can utilize a complication atlas, though an advantage of the rank sum method is the ability to incorporate all complication grades without the need for grade dichotomization. (note)

Private sector involvement in times of armed conflict: What are the constraints for trading medical equipment?

Science.gov (United States)

Schmidt, Georg

Today, healthcare facilities are highly dependent on the private sector to keep their medical equipment functioning. Moreover, private sector involvement becomes particularly important for the supply of spare parts and consumables. However, in times of armed conflict, the capacity of the corporate world appears to be seriously hindered. Subsequently, this study researches the influence of armed conflict on the private medical equipment sector. This study follows a qualitative approach by conducting 19 interviews with representatives of the corporate world in an active conflict zone. A semistructured interview guide, consisting of 10 questions, was used to examine the constraints of this sector. The results reveal that the lack of skilled personnel, complicated importation procedures, and a decrease in financial capacity are the major constraints faced by private companies dealing in medical equipment in conflict zones. Even when no official sanctions and embargoes for medical items exist, constraints for trading medical equipment are clearly recognizable. Countries at war would benefit from a centralized structure that deals with the importation procedures for medical items, to assist local companies in their purchasing procedures. A high degree of adaption is needed to continue operating, despite the emerging constraints of armed conflict. Future studies might research the constraints for manufacturers outside the conflict to export medical items to the country of war.

Integral constraints on perturbations of Robertson-Walker cosmologies

International Nuclear Information System (INIS)

Ellis, G.F.R.; Jaklitsch, M.J.

1989-01-01

Integral constraints occur in the case of spherically symmetric inhomogeneities in Robertson-Walker universes, and (according to Traschen) in the case of general perturbations of these models. It is shown that these constraints are the same in the case of spherical symmetry, and they are interpreted as 'fitting conditions', that is, as constraints on the background Robertson-Walker model rather than on the nature of inhomogeneities. These integral constraints significantly affect the interpretation of anisotropies in the cosmic microwave background radiation. 22 refs

Study on the unified constraint parameter for characterizing in-plane and out-of-plane constraint based on the equivalent plastic strain

International Nuclear Information System (INIS)

Yang Jie; Wang Guozhen; Xuan Fuzhen; Tu Shandong

2013-01-01

Background: Constraint can significantly alter the material's fracture toughness. Purpose: In order to increase accuracy of the structural integrity assessment. It needs to consider the effect of constraint on the fracture toughness of nuclear power materials and structures. A unified measure which can reflect both in-plane and out-of-plane constraint is needed. Methods: In this paper, the finite element numerical simulation method was used, a unified measure and characterization parameter of in-plane and out-of-plane constraint based on crack-tip equivalent plastic strain have been investigated. Results: The results show that the area surrounded by ε p isoline has a good relevance with the material's fracture toughness on different constraint conditions, so it may be a suitable parameter. Based on the area A PEEQ , a unified constraint characterization parameter √A p is defined. It was found that there exists a sole linear relation between the normalized fracture toughness J IC /J re f and √A p regardless of the in-plane, out-of-plane constraint and the selection of the p isolines. The sole J IC /J re f-√A p line exists for a certain material. For different materials, the slope of J IC /J re f-√A p reference line is different. The material whose slope is larger has a higher J IC /J re f and is more sensitive to constraint at the same magnitude of normalized unified parameter. Conclusions: The unified J IC /J re f -√A p reference line may be used to assess the safety of a cracked component with any constraint levels regardless of in-plane or out-of-plane constraint or both. (authors)

Fluid convection, constraint and causation

Science.gov (United States)

Bishop, Robert C.

2012-01-01

Complexity—nonlinear dynamics for my purposes in this essay—is rich with metaphysical and epistemological implications but is receiving sustained philosophical analysis only recently. I will explore some of the subtleties of causation and constraint in Rayleigh–Bénard convection as an example of a complex phenomenon, and extract some lessons for further philosophical reflection on top-down constraint and causation particularly with respect to causal foundationalism. PMID:23386955

Freedom and constraint analysis and optimization

NARCIS (Netherlands)

Brouwer, Dannis Michel; Boer, Steven; Aarts, Ronald G.K.M.; Meijaard, Jacob Philippus; Jonker, Jan B.

2011-01-01

Many mathematical and intuitive methods for constraint analysis of mechanisms have been proposed. In this article we compare three methods. Method one is based on Grüblers equation. Method two uses an intuitive analysis method based on opening kinematic loops and evaluating the constraints at the

Constraint theory multidimensional mathematical model management

CERN Document Server

Friedman, George J

2017-01-01

Packed with new material and research, this second edition of George Friedman’s bestselling Constraint Theory remains an invaluable reference for all engineers, mathematicians, and managers concerned with modeling. As in the first edition, this text analyzes the way Constraint Theory employs bipartite graphs and presents the process of locating the “kernel of constraint” trillions of times faster than brute-force approaches, determining model consistency and computational allowability. Unique in its abundance of topological pictures of the material, this book balances left- and right-brain perceptions to provide a thorough explanation of multidimensional mathematical models. Much of the extended material in this new edition also comes from Phan Phan’s PhD dissertation in 2011, titled “Expanding Constraint Theory to Determine Well-Posedness of Large Mathematical Models.” Praise for the first edition: "Dr. George Friedman is indisputably the father of the very powerful methods of constraint theory...

Dose constraints, what are they now?

International Nuclear Information System (INIS)

Lazo, T.

2005-01-01

The concept of a source-related dose constraint was first introduced in ICPR publication 60. The idea was to provide a number that individual exposures from a single, specific source should not exceed, and below which optimisation of protection should take place. Dose constraints were applied to occupational and public exposures from practices. In order to simplify and clarify the ICRP's recommendations, the latest draft, RPO5, presents dose constraints again, and with the same meaning as in publication 60. However, the dose constraints are now applied in all situations, not just practices. This new approach does provide simplification, in that a single concept is applied to all types of exposures (normal situations, accident situations, and existing situations). However, the approach and numerical values that are selected by regulatory authorities for the application of the concept, particularly in normal situations which are also subject to dose limits, will be crucial to the implementation of the system of radiological protection. (author)

Constraints to Strategy Implementation and their Influence on Business Performance: the Case of a Waste Management Logistics Company

Directory of Open Access Journals (Sweden)

Chengedzai Mafini

2016-08-01

Full Text Available Waste management companies in developing countries often have to contend with a plethora of factors that inhibit their business performance. The primary objective of this study was to investigate the influence of constraints to strategy implementation on the business performance of a waste management logistics company in South Africa. The study was triggered by the lack of previous research focusing on constraints to strategy implementation in the waste management sector. The study employed a quantitative approach using the cross sectional survey design in which data were collected from 309 employees of a waste management logistics company based in Gauteng Province. Seven constraints to strategy implementation; namely, management practices, human resource capabilities, customer service, external orientation, internal communication, innovation and employee motivation were identified through Exploratory Factor Analysis. Pearson correlations showed that business performance is negatively affected as and when each constraint becomes more prevalent. Regression analysis showed that all constraints were statistically significant. To academics, the study provides current insights on factors impacting on business performance in waste management organisations. Management practitioners may improve the levels of business performance through structural adjustments of the seven constraints identified in this study. The study may be used as a reference point in the diagnosis of business performance related challenges in companies operating within the waste management sector.

Minimization and parameter estimation for seminorm regularization models with I-divergence constraints

International Nuclear Information System (INIS)

Teuber, T; Steidl, G; Chan, R H

2013-01-01

In this paper, we analyze the minimization of seminorms ‖L · ‖ on R n under the constraint of a bounded I-divergence D(b, H · ) for rather general linear operators H and L. The I-divergence is also known as Kullback–Leibler divergence and appears in many models in imaging science, in particular when dealing with Poisson data but also in the case of multiplicative Gamma noise. Often H represents, e.g., a linear blur operator and L is some discrete derivative or frame analysis operator. A central part of this paper consists in proving relations between the parameters of I-divergence constrained and penalized problems. To solve the I-divergence constrained problem, we consider various first-order primal–dual algorithms which reduce the problem to the solution of certain proximal minimization problems in each iteration step. One of these proximation problems is an I-divergence constrained least-squares problem which can be solved based on Morozov’s discrepancy principle by a Newton method. We prove that these algorithms produce not only a sequence of vectors which converges to a minimizer of the constrained problem but also a sequence of parameters which converges to a regularization parameter so that the corresponding penalized problem has the same solution. Furthermore, we derive a rule for automatically setting the constraint parameter for data corrupted by multiplicative Gamma noise. The performance of the various algorithms is finally demonstrated for different image restoration tasks both for images corrupted by Poisson noise and multiplicative Gamma noise. (paper)

Simulating non-holonomic constraints within the LCP-based simulation framework

DEFF Research Database (Denmark)

Ellekilde, Lars-Peter; Petersen, Henrik Gordon

2006-01-01

be incorporated directly, and derive formalism for how the non-holonomic contact constraints can be modelled as a combination of non-holonomic equality constraints and ordinary contacts constraints. For each of these three we are able to guarantee solvability, when using Lemke's algorithm. A number of examples......In this paper, we will extend the linear complementarity problem-based rigid-body simulation framework with non-holonomic constraints. We consider three different types of such, namely equality, inequality and contact constraints. We show how non-holonomic equality and inequality constraints can...... are included to demonstrate the non-holonomic constraints. Udgivelsesdato: Marts...

DELPHI ANALYSIS OF CONSTRAINTS TO MAIZE PRODUCTION IN ...

African Journals Online (AJOL)

A descriptive Delphi study was conducted to: identify constraints to maize production on SNL from the perspectives of crop researchers, extension officers and farmers; categorise the constraints; rank them in order of importance; and identify ways of addressing them. A total of 33 constraint items were identified and ...

Near-Optimal Fingerprinting with Constraints

Directory of Open Access Journals (Sweden)

Gulyás Gábor György

2016-10-01

Full Text Available Several recent studies have demonstrated that people show large behavioural uniqueness. This has serious privacy implications as most individuals become increasingly re-identifiable in large datasets or can be tracked, while they are browsing the web, using only a couple of their attributes, called as their fingerprints. Often, the success of these attacks depends on explicit constraints on the number of attributes learnable about individuals, i.e., the size of their fingerprints. These constraints can be budget as well as technical constraints imposed by the data holder. For instance, Apple restricts the number of applications that can be called by another application on iOS in order to mitigate the potential privacy threats of leaking the list of installed applications on a device. In this work, we address the problem of identifying the attributes (e.g., smartphone applications that can serve as a fingerprint of users given constraints on the size of the fingerprint. We give the best fingerprinting algorithms in general, and evaluate their effectiveness on several real-world datasets. Our results show that current privacy guards limiting the number of attributes that can be queried about individuals is insufficient to mitigate their potential privacy risks in many practical cases.

Coverage-based constraints for IMRT optimization

Science.gov (United States)

Mescher, H.; Ulrich, S.; Bangert, M.

2017-09-01

Radiation therapy treatment planning requires an incorporation of uncertainties in order to guarantee an adequate irradiation of the tumor volumes. In current clinical practice, uncertainties are accounted for implicitly with an expansion of the target volume according to generic margin recipes. Alternatively, it is possible to account for uncertainties by explicit minimization of objectives that describe worst-case treatment scenarios, the expectation value of the treatment or the coverage probability of the target volumes during treatment planning. In this note we show that approaches relying on objectives to induce a specific coverage of the clinical target volumes are inevitably sensitive to variation of the relative weighting of the objectives. To address this issue, we introduce coverage-based constraints for intensity-modulated radiation therapy (IMRT) treatment planning. Our implementation follows the concept of coverage-optimized planning that considers explicit error scenarios to calculate and optimize patient-specific probabilities q(\\hat{d}, \\hat{v}) of covering a specific target volume fraction \\hat{v} with a certain dose \\hat{d} . Using a constraint-based reformulation of coverage-based objectives we eliminate the trade-off between coverage and competing objectives during treatment planning. In-depth convergence tests including 324 treatment plan optimizations demonstrate the reliability of coverage-based constraints for varying levels of probability, dose and volume. General clinical applicability of coverage-based constraints is demonstrated for two cases. A sensitivity analysis regarding penalty variations within this planing study based on IMRT treatment planning using (1) coverage-based constraints, (2) coverage-based objectives, (3) probabilistic optimization, (4) robust optimization and (5) conventional margins illustrates the potential benefit of coverage-based constraints that do not require tedious adjustment of target volume objectives.

Pairwise Constraint-Guided Sparse Learning for Feature Selection.

Science.gov (United States)

Liu, Mingxia; Zhang, Daoqiang

2016-01-01

Feature selection aims to identify the most informative features for a compact and accurate data representation. As typical supervised feature selection methods, Lasso and its variants using L1-norm-based regularization terms have received much attention in recent studies, most of which use class labels as supervised information. Besides class labels, there are other types of supervised information, e.g., pairwise constraints that specify whether a pair of data samples belong to the same class (must-link constraint) or different classes (cannot-link constraint). However, most of existing L1-norm-based sparse learning methods do not take advantage of the pairwise constraints that provide us weak and more general supervised information. For addressing that problem, we propose a pairwise constraint-guided sparse (CGS) learning method for feature selection, where the must-link and the cannot-link constraints are used as discriminative regularization terms that directly concentrate on the local discriminative structure of data. Furthermore, we develop two variants of CGS, including: 1) semi-supervised CGS that utilizes labeled data, pairwise constraints, and unlabeled data and 2) ensemble CGS that uses the ensemble of pairwise constraint sets. We conduct a series of experiments on a number of data sets from University of California-Irvine machine learning repository, a gene expression data set, two real-world neuroimaging-based classification tasks, and two large-scale attribute classification tasks. Experimental results demonstrate the efficacy of our proposed methods, compared with several established feature selection methods.

[Operative vaginal deliveries training].

Science.gov (United States)

Dupuis, O

2008-12-01

The appropriate use of forceps, vacuums or spatulas facilitates the rapid delivery of foetuses faced with life-threatening situations. It also makes possible the relief of certain cases of prolonged second-stage labor. In France, operative vaginal delivery (OVD) accounts for approximately 10% of all births. OVD training aims to optimize maternal, as well as neonatal safety. It should enable trainees to indicate or contraindicate an OVD safely, as well as to choose the appropriate instrument, use it correctly, and master quality control principles. Traditional OVD training is confronted with both spatial and time-related limitations. Spatial constraints involve both the teacher and trainee who only have limited visual access to the pelvic canal, and the head of the foetus; the time constraint occurs whenever the OVD occurs in an emergency setting. These limitations have been further aggravated by new constraints: decreasing time dedicated to training (European safety rules prohibit work the day after night duty), increasing litigation, and constraints imposed by society. Training by means of simulation removes such limitations making it possible to both avoid exposing pregnant women to the hazards of traditional training, and adapt the training to the skills of each trainee. OVD training should include forceps, vacuums and the use of spatulas. The OVD skills of obstetricians should be audited regularly on both a personal and a confidential level. Such audits could be based on a method using a simulator. Prospective studies comparing traditional and simulation-based training should be encouraged.

Chance-Constrained Guidance With Non-Convex Constraints

Science.gov (United States)

Ono, Masahiro

2011-01-01

Missions to small bodies, such as comets or asteroids, require autonomous guidance for descent to these small bodies. Such guidance is made challenging by uncertainty in the position and velocity of the spacecraft, as well as the uncertainty in the gravitational field around the small body. In addition, the requirement to avoid collision with the asteroid represents a non-convex constraint that means finding the optimal guidance trajectory, in general, is intractable. In this innovation, a new approach is proposed for chance-constrained optimal guidance with non-convex constraints. Chance-constrained guidance takes into account uncertainty so that the probability of collision is below a specified threshold. In this approach, a new bounding method has been developed to obtain a set of decomposed chance constraints that is a sufficient condition of the original chance constraint. The decomposition of the chance constraint enables its efficient evaluation, as well as the application of the branch and bound method. Branch and bound enables non-convex problems to be solved efficiently to global optimality. Considering the problem of finite-horizon robust optimal control of dynamic systems under Gaussian-distributed stochastic uncertainty, with state and control constraints, a discrete-time, continuous-state linear dynamics model is assumed. Gaussian-distributed stochastic uncertainty is a more natural model for exogenous disturbances such as wind gusts and turbulence than the previously studied set-bounded models. However, with stochastic uncertainty, it is often impossible to guarantee that state constraints are satisfied, because there is typically a non-zero probability of having a disturbance that is large enough to push the state out of the feasible region. An effective framework to address robustness with stochastic uncertainty is optimization with chance constraints. These require that the probability of violating the state constraints (i.e., the probability of

Specifying Dynamic and Deontic Integrity Constraints

NARCIS (Netherlands)

Wieringa, Roelf J.; Meyer, John-Jules; Weigand, Hans

In the dominant view of knowledge bases (KB's), a KB is a set of facts (atomic sentences) and integrity constraints (IC's). An IC is then a sentence which must at least be consistent with the other sentences in the KB, This view obliterates the distinction between, for example, the constraint that

Stability Constraints for Robust Model Predictive Control

Directory of Open Access Journals (Sweden)

Amanda G. S. Ottoni

2015-01-01

Full Text Available This paper proposes an approach for the robust stabilization of systems controlled by MPC strategies. Uncertain SISO linear systems with box-bounded parametric uncertainties are considered. The proposed approach delivers some constraints on the control inputs which impose sufficient conditions for the convergence of the system output. These stability constraints can be included in the set of constraints dealt with by existing MPC design strategies, in this way leading to the “robustification” of the MPC.

Parallel Execution of Multi Set Constraint Rewrite Rules

DEFF Research Database (Denmark)

Sulzmann, Martin; Lam, Edmund Soon Lee

2008-01-01

that the underlying constraint rewrite implementation executes rewrite steps in parallel on increasingly popular becoming multi-core architectures. We design and implement efficient algorithms which allow for the parallel execution of multi-set constraint rewrite rules. Our experiments show that we obtain some......Multi-set constraint rewriting allows for a highly parallel computational model and has been used in a multitude of application domains such as constraint solving, agent specification etc. Rewriting steps can be applied simultaneously as long as they do not interfere with each other.We wish...

Neuroadaptive Fault-Tolerant Control of Nonlinear Systems Under Output Constraints and Actuation Faults.

Science.gov (United States)

Zhao, Kai; Song, Yongduan; Shen, Zhixi

2018-02-01

In this paper, a neuroadaptive fault-tolerant tracking control method is proposed for a class of time-delay pure-feedback systems in the presence of external disturbances and actuation faults. The proposed controller can achieve prescribed transient and steady-state performance, despite uncertain time delays and output constraints as well as actuation faults. By combining a tangent barrier Lyapunov-Krasovskii function with the dynamic surface control technique, the neural network unit in the developed control scheme is able to take its action from the very beginning and play its learning/approximating role safely during the entire system operational envelope, leading to enhanced control performance without the danger of violating compact set precondition. Furthermore, prescribed transient performance and output constraints are strictly ensured in the presence of nonaffine uncertainties, external disturbances, and undetectable actuation faults. The control strategy is also validated by numerical simulation.

[The Nature and Issues of Drug Addiction Treatment under Constraint].

Science.gov (United States)

Quirion, Bastien

This article is exploring different forms of constraint that are exerted in the field of drug addiction treatment. The objective of this article is to establish benchmarks and to stimulate reflection about the ethical and clinical implications of those constraints in the field of drug addiction treatment. This article is presenting a critical review of different forms of constraint that can be exerted in Canada in regard to the treatment of drug addiction. In the first section of the article, a definition of therapeutic intervention is proposed, that includes the dimension of power, which justifies the importance of considering the coercive aspects of treatment. The second section, which represents the core section of the paper, is devoted to the presentation of different levels of constraint that can be distinguished in regard to drug addicts who are under treatment. Three levels of constraint are exposed: judicial constraint, institutional constraint and relational constraint. The coercive aspect of treatment can then be recognized as a combination of all tree levels of constraint. Judicial constraint refers to any form of constraint in which the court or the judge is imposing or recommending treatment. This particular level of constraint can take different forms, such as therapeutic remands, conditions of a probation order, conditions of a conditional sentence of imprisonment, and coercive treatment such as the ones provided through drug courts. Institutional constraint refers to any form of constraint exerted within any institutional setting, such as correctional facilities and programs offered in community. Correctional facilities being limited by their own specific mission, it might have a major impact on the way the objectives of treatment are defined. Those limitations can then be considered as a form of constraint, in which drug users don't have much space to express their personal needs. Finally, relational constraint refers to any form of constraint in

Optimizing Wind And Hydropower Generation Within Realistic Reservoir Operating Policy

Science.gov (United States)

Magee, T. M.; Clement, M. A.; Zagona, E. A.

2012-12-01

Previous studies have evaluated the benefits of utilizing the flexibility of hydropower systems to balance the variability and uncertainty of wind generation. However, previous hydropower and wind coordination studies have simplified non-power constraints on reservoir systems. For example, some studies have only included hydropower constraints on minimum and maximum storage volumes and minimum and maximum plant discharges. The methodology presented here utilizes the pre-emptive linear goal programming optimization solver in RiverWare to model hydropower operations with a set of prioritized policy constraints and objectives based on realistic policies that govern the operation of actual hydropower systems, including licensing constraints, environmental constraints, water management and power objectives. This approach accounts for the fact that not all policy constraints are of equal importance. For example target environmental flow levels may not be satisfied if it would require violating license minimum or maximum storages (pool elevations), but environmental flow constraints will be satisfied before optimizing power generation. Additionally, this work not only models the economic value of energy from the combined hydropower and wind system, it also captures the economic value of ancillary services provided by the hydropower resources. It is recognized that the increased variability and uncertainty inherent with increased wind penetration levels requires an increase in ancillary services. In regions with liberalized markets for ancillary services, a significant portion of hydropower revenue can result from providing ancillary services. Thus, ancillary services should be accounted for when determining the total value of a hydropower system integrated with wind generation. This research shows that the end value of integrated hydropower and wind generation is dependent on a number of factors that can vary by location. Wind factors include wind penetration level

Real-time aircraft continuous descent trajectory optimization with ATC time constraints using direct collocation methods.

OpenAIRE

Verhoeven, Ronald; Dalmau Codina, Ramon; Prats Menéndez, Xavier; de Gelder, Nico

2014-01-01

1 Abstract In this paper an initial implementation of a real - time aircraft trajectory optimization algorithm is presented . The aircraft trajectory for descent and approach is computed for minimum use of thrust and speed brake in support of a “green” continuous descent and approach flight operation, while complying with ATC time constraints for maintaining runway throughput and co...

Integrated systems optimization model for biofuel development: The influence of environmental constraints

Science.gov (United States)

Housh, M.; Ng, T.; Cai, X.

2012-12-01

The environmental impact is one of the major concerns of biofuel development. While many other studies have examined the impact of biofuel expansion on stream flow and water quality, this study examines the problem from the other side - will and how a biofuel production target be affected by given environmental constraints. For this purpose, an integrated model comprises of different sub-systems of biofuel refineries, transportation, agriculture, water resources and crops/ethanol market has been developed. The sub-systems are integrated into one large-scale model to guide the optimal development plan considering the interdependency between the subsystems. The optimal development plan includes biofuel refineries location and capacity, refinery operation, land allocation between biofuel and food crops, and the corresponding stream flow and nitrate load in the watershed. The watershed is modeled as a network flow, in which the nodes represent sub-watersheds and the arcs are defined as the linkage between the sub-watersheds. The runoff contribution of each sub-watershed is determined based on the land cover and the water uses in that sub-watershed. Thus, decisions of other sub-systems such as the land allocation in the land use sub-system and the water use in the refinery sub-system define the sources and the sinks of the network. Environmental policies will be addressed in the integrated model by imposing stream flow and nitrate load constraints. These constraints can be specified by location and time in the watershed to reflect the spatial and temporal variation of the regulations. Preliminary results show that imposing monthly water flow constraints and yearly nitrate load constraints will change the biofuel development plan dramatically. Sensitivity analysis is performed to examine how the environmental constraints and their spatial and the temporal distribution influence the overall biofuel development plan and the performance of each of the sub

A novel constraint for thermodynamically designing DNA sequences.

Directory of Open Access Journals (Sweden)

Qiang Zhang

Full Text Available Biotechnological and biomolecular advances have introduced novel uses for DNA such as DNA computing, storage, and encryption. For these applications, DNA sequence design requires maximal desired (and minimal undesired hybridizations, which are the product of a single new DNA strand from 2 single DNA strands. Here, we propose a novel constraint to design DNA sequences based on thermodynamic properties. Existing constraints for DNA design are based on the Hamming distance, a constraint that does not address the thermodynamic properties of the DNA sequence. Using a unique, improved genetic algorithm, we designed DNA sequence sets which satisfy different distance constraints and employ a free energy gap based on a minimum free energy (MFE to gauge DNA sequences based on set thermodynamic properties. When compared to the best constraints of the Hamming distance, our method yielded better thermodynamic qualities. We then used our improved genetic algorithm to obtain lower-bound DNA sequence sets. Here, we discuss the effects of novel constraint parameters on the free energy gap.

Multi-objective control of nonlinear boiler-turbine dynamics with actuator magnitude and rate constraints.

Science.gov (United States)

Chen, Pang-Chia

2013-01-01

This paper investigates multi-objective controller design approaches for nonlinear boiler-turbine dynamics subject to actuator magnitude and rate constraints. System nonlinearity is handled by a suitable linear parameter varying system representation with drum pressure as the system varying parameter. Variation of the drum pressure is represented by suitable norm-bounded uncertainty and affine dependence on system matrices. Based on linear matrix inequality algorithms, the magnitude and rate constraints on the actuator and the deviations of fluid density and water level are formulated while the tracking abilities on the drum pressure and power output are optimized. Variation ranges of drum pressure and magnitude tracking commands are used as controller design parameters, determined according to the boiler-turbine's operation range. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

Constraint programming and decision making

CERN Document Server

Kreinovich, Vladik

2014-01-01

In many application areas, it is necessary to make effective decisions under constraints. Several area-specific techniques are known for such decision problems; however, because these techniques are area-specific, it is not easy to apply each technique to other applications areas. Cross-fertilization between different application areas is one of the main objectives of the annual International Workshops on Constraint Programming and Decision Making. Those workshops, held in the US (El Paso, Texas), in Europe (Lyon, France), and in Asia (Novosibirsk, Russia), from 2008 to 2012, have attracted researchers and practitioners from all over the world. This volume presents extended versions of selected papers from those workshops. These papers deal with all stages of decision making under constraints: (1) formulating the problem of multi-criteria decision making in precise terms, (2) determining when the corresponding decision problem is algorithmically solvable; (3) finding the corresponding algorithms, and making...

Biological constraints do not entail cognitive closure.

Science.gov (United States)

Vlerick, Michael

2014-12-01

From the premise that our biology imposes cognitive constraints on our epistemic activities, a series of prominent authors--most notably Fodor, Chomsky and McGinn--have argued that we are cognitively closed to certain aspects and properties of the world. Cognitive constraints, they argue, entail cognitive closure. I argue that this is not the case. More precisely, I detect two unwarranted conflations at the core of arguments deriving closure from constraints. The first is a conflation of what I will refer to as 'representation' and 'object of representation'. The second confuses the cognitive scope of the assisted mind for that of the unassisted mind. Cognitive closure, I conclude, cannot be established from pointing out the (uncontroversial) existence of cognitive constraints. Copyright © 2014 Elsevier Ltd. All rights reserved.

Level-Set Topology Optimization with Aeroelastic Constraints

Science.gov (United States)

Dunning, Peter D.; Stanford, Bret K.; Kim, H. Alicia

2015-01-01

Level-set topology optimization is used to design a wing considering skin buckling under static aeroelastic trim loading, as well as dynamic aeroelastic stability (flutter). The level-set function is defined over the entire 3D volume of a transport aircraft wing box. Therefore, the approach is not limited by any predefined structure and can explore novel configurations. The Sequential Linear Programming (SLP) level-set method is used to solve the constrained optimization problems. The proposed method is demonstrated using three problems with mass, linear buckling and flutter objective and/or constraints. A constraint aggregation method is used to handle multiple buckling constraints in the wing skins. A continuous flutter constraint formulation is used to handle difficulties arising from discontinuities in the design space caused by a switching of the critical flutter mode.

Constraint Logic Programming approach to protein structure prediction

Directory of Open Access Journals (Sweden)

Fogolari Federico

2004-11-01

Full Text Available Abstract Background The protein structure prediction problem is one of the most challenging problems in biological sciences. Many approaches have been proposed using database information and/or simplified protein models. The protein structure prediction problem can be cast in the form of an optimization problem. Notwithstanding its importance, the problem has very seldom been tackled by Constraint Logic Programming, a declarative programming paradigm suitable for solving combinatorial optimization problems. Results Constraint Logic Programming techniques have been applied to the protein structure prediction problem on the face-centered cube lattice model. Molecular dynamics techniques, endowed with the notion of constraint, have been also exploited. Even using a very simplified model, Constraint Logic Programming on the face-centered cube lattice model allowed us to obtain acceptable results for a few small proteins. As a test implementation their (known secondary structure and the presence of disulfide bridges are used as constraints. Simplified structures obtained in this way have been converted to all atom models with plausible structure. Results have been compared with a similar approach using a well-established technique as molecular dynamics. Conclusions The results obtained on small proteins show that Constraint Logic Programming techniques can be employed for studying protein simplified models, which can be converted into realistic all atom models. The advantage of Constraint Logic Programming over other, much more explored, methodologies, resides in the rapid software prototyping, in the easy way of encoding heuristics, and in exploiting all the advances made in this research area, e.g. in constraint propagation and its use for pruning the huge search space.

Constraint Logic Programming approach to protein structure prediction.

Science.gov (United States)

Dal Palù, Alessandro; Dovier, Agostino; Fogolari, Federico

2004-11-30

The protein structure prediction problem is one of the most challenging problems in biological sciences. Many approaches have been proposed using database information and/or simplified protein models. The protein structure prediction problem can be cast in the form of an optimization problem. Notwithstanding its importance, the problem has very seldom been tackled by Constraint Logic Programming, a declarative programming paradigm suitable for solving combinatorial optimization problems. Constraint Logic Programming techniques have been applied to the protein structure prediction problem on the face-centered cube lattice model. Molecular dynamics techniques, endowed with the notion of constraint, have been also exploited. Even using a very simplified model, Constraint Logic Programming on the face-centered cube lattice model allowed us to obtain acceptable results for a few small proteins. As a test implementation their (known) secondary structure and the presence of disulfide bridges are used as constraints. Simplified structures obtained in this way have been converted to all atom models with plausible structure. Results have been compared with a similar approach using a well-established technique as molecular dynamics. The results obtained on small proteins show that Constraint Logic Programming techniques can be employed for studying protein simplified models, which can be converted into realistic all atom models. The advantage of Constraint Logic Programming over other, much more explored, methodologies, resides in the rapid software prototyping, in the easy way of encoding heuristics, and in exploiting all the advances made in this research area, e.g. in constraint propagation and its use for pruning the huge search space.

Hybrid Discrete Differential Evolution Algorithm for Lot Splitting with Capacity Constraints in Flexible Job Scheduling

Directory of Open Access Journals (Sweden)

Xinli Xu

2013-01-01

Full Text Available A two-level batch chromosome coding scheme is proposed to solve the lot splitting problem with equipment capacity constraints in flexible job shop scheduling, which includes a lot splitting chromosome and a lot scheduling chromosome. To balance global search and local exploration of the differential evolution algorithm, a hybrid discrete differential evolution algorithm (HDDE is presented, in which the local strategy with dynamic random searching based on the critical path and a random mutation operator is developed. The performance of HDDE was experimented with 14 benchmark problems and the practical dye vat scheduling problem. The simulation results showed that the proposed algorithm has the strong global search capability and can effectively solve the practical lot splitting problems with equipment capacity constraints.

Efficiency and constraints in transport planning. [Denmark]. Effektivitet og barrierer i transportplanlaegningen

Energy Technology Data Exchange (ETDEWEB)

Skjoett-Larsen, T.

1991-06-15

Results from several of the research projects financed by the Danish Ministry of Energy have shown that there are potentials for saving energy and reducing operational costs which can be fulfilled through improved planning of industrial transport projects. Yet it has also been observed that many good ideas are seldom put into practice. The factors which act as constraints to the realization of possible solutions to transport problems are examined. Fourteen industrial companies were interviewed in relation to their distribution planning. Recommendations for a more efficient mediation of research results to target groups are offered. Relevant data from named Danish firms are presented. The named constraints are claimed to be insufficient knowledge (of research results in this area), lack of definition of effectivity targets, unsatisfactory motivation and training of personnel, organisational barriers and external barriers such as trucks that are too small, ferry taxes that are too high, road and rail networks that are in need of extension etc. These problems are discussed. (AB).

A minimal collision operator for implementing neoclassical transport in gyrokinetic simulations

International Nuclear Information System (INIS)

Garbet, X.; Dif-Pradalier, G.; Nguyen, C.; Angelino, P.; Sarazin, Y.; Grandgirard, V.; Ghendrih, P.; Samain, A.

2008-01-01

This paper presents a class of collision operators, which reproduce neoclassical transport and comply with the constraints of a full-f global gyrokinetic code. The assessment of these operators is based on a variational entropy method, which allows a fast calculation of the neoclassical diffusivity and poloidal velocity.

Modifier constraints in alkali ultraphosphate glasses

DEFF Research Database (Denmark)

Rodrigues, B.P.; Mauro, J.C.; Yue, Yuanzheng

2014-01-01

In applying the recently introduced concept of cationic constraint strength [J. Chem. Phys. 140, 214501 (2014)] to bond constraint theory (BCT) of binary phosphate glasses in the ultraphosphate region of xR2O-(1-x)P2O5 (with x ≤ 0.5 and R = {Li, Na, Cs}), we demonstrate that a fundamental limitat...

Quantization of (2 + 1)-spinning particles and bifermionic constraint problem

Energy Technology Data Exchange (ETDEWEB)

Fresneda, R [Instituto de FIsica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, SP (Brazil); Gavrilov, S P [Instituto de FIsica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, SP (Brazil); Gitman, D M [Instituto de FIsica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, SP (Brazil); Moshin, P Yu [Instituto de FIsica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, SP (Brazil)

2004-03-21

This work is a natural continuation of our recent study in quantizing relativistic particles. There it was demonstrated that, by applying a consistent quantization scheme to the classical model of a spinless relativistic particle as well as to the Berezin-Marinov model of a 3 + 1 Dirac particle, it is possible to obtain a consistent relativistic quantum mechanics of such particles. In the present paper, we apply a similar approach to the problem of quantizing the massive 2 + 1 Dirac particle. However, we stress that such a problem differs in a nontrivial way from the one in 3 + 1 dimensions. The point is that in 2 + 1 dimensions each spin polarization describes different fermion species. Technically this fact manifests itself through the presence of a bifermionic constant and of a bifermionic first-class constraint. In particular, this constraint does not admit a conjugate gauge condition at the classical level. The quantization problem in 2 + 1 dimensions is also interesting from the physical viewpoint (e.g., anyons). In order to quantize the model, we first derive a classical formulation in an effective phase space, restricted by constraints and gauges. Then the condition of preservation of the classical symmetries allows us to realize the operator algebra in an unambiguous way and construct an appropriate Hilbert space. The physical sector of the constructed quantum mechanics contains spin-1/2 particles and antiparticles without an infinite number of negative-energy levels, and exactly reproduces the one-particle sector of the 2 + 1 quantum theory of a spinor field.

A Three-Phase Microgrid Restoration Model Considering Unbalanced Operation of Distributed Generation

International Nuclear Information System (INIS)

Wang, Zeyu; Wang, Jianhui; Chen, Chen

2016-01-01

Recent severe outages highlight the urgency of improving grid resiliency in the U.S. Microgrid formation schemes are proposed to restore critical loads after outages occur. Most distribution networks have unbalanced configurations that are not represented in sufficient detail by single-phase models. This study provides a microgrid formation plan that adopts a three-phase network model to represent unbalanced distribution networks. The problem formulation has a quadratic objective function with mixed-integer linear constraints. The three-phase network model enables us to examine the three-phase power outputs of distributed generators (DGs), preventing unbalanced operation that might trip DGs. Because the DG unbalanced operation constraint is non-convex, an iterative process is presented that checks whether the unbalanced operation limits for DGs are satisfied after each iteration of optimization. We also develop a relatively conservative linear approximation on the unbalanced operation constraint to handle larger networks. Compared with the iterative solution process, the conservative linear approximation is able to accelerate the solution process at the cost of sacrificing optimality to a limited extent. Simulation in the IEEE 34 node and IEEE 123 test feeders indicate that the proposed method yields more practical microgrid formations results. In addition, this paper explores the coordinated operation of DGs and energy storage (ES) installations. The unbalanced three-phase outputs of ESs combined with the relatively balanced outputs of DGs could supply unbalanced loads. In conclusion, the case study also validates the DG-ES coordination.

SMEs and their co-operation with academia.

Science.gov (United States)

Antoine, Jean Michel; Strömqvist, Mats

2005-01-01

Co-operation between SMEs and Academia can be a win-win situation when each partner understands the constraints of the other. SMEs are often leaders in innovation; therefore more ready to share interest in research. They are flexible and dynamic. They need a short feed-back to sustain their co-operation. Academia is often more long-term oriented and more question- than answer-oriented. A code of conduct can ease the relationship because it can anticipate the potential problems.

Implicit Motives and Men’s Perceived Constraint in Fatherhood

Science.gov (United States)

Ruppen, Jessica; Waldvogel, Patricia; Ehlert, Ulrike

2016-01-01

Research shows that implicit motives influence social relationships. However, little is known about their role in fatherhood and, particularly, how men experience their paternal role. Therefore, this study examined the association of implicit motives and fathers’ perceived constraint due to fatherhood. Furthermore, we explored their relation to fathers’ life satisfaction. Participants were fathers with biological children (N = 276). They were asked to write picture stories, which were then coded for implicit affiliation and power motives. Perceived constraint and life satisfaction were assessed on a visual analog scale. A higher implicit need for affiliation was significantly associated with lower perceived constraint, whereas the implicit need for power had the opposite effect. Perceived constraint had a negative influence on life satisfaction. Structural equation modeling revealed significant indirect effects of implicit affiliation and power motives on life satisfaction mediated by perceived constraint. Our findings indicate that men with a higher implicit need for affiliation experience less constraint due to fatherhood, resulting in higher life satisfaction. The implicit need for power, however, results in more perceived constraint and is related to decreased life satisfaction. PMID:27933023

Medical image segmentation by a constraint satisfaction neural network

International Nuclear Information System (INIS)

Chen, C.T.; Tsao, E.C.K.; Lin, W.C.

1991-01-01

This paper proposes a class of Constraint Satisfaction Neural Networks (CSNNs) for solving the problem of medical image segmentation which can be formulated as a Constraint Satisfaction Problem (CSP). A CSNN consists of a set of objects, a set of labels for each object, a collection of constraint relations linking the labels of neighboring objects, and a topological constraint describing the neighborhood relationship among various objects. Each label for a particular object indicates one possible interpretation for that object. The CSNN can be viewed as a collection of neurons that interconnect with each other. The connections and the topology of a CSNN are used to represent the constraints in a CSP. The mechanism of the neural network is to find a solution that satisfies all the constraints in order to achieve a global consistency. The final solution outlines segmented areas and simultaneously satisfies all the constraints. This technique has been applied to medical images and the results show that this CSNN method is a very promising approach for image segmentation

Implicit Motives and Men’s Perceived Constraint in Fatherhood

Directory of Open Access Journals (Sweden)

Jessica Ruppen

2016-11-01

Full Text Available Research shows that implicit motives influence social relationships. However, little is known about their role in fatherhood and, particularly, how men experience their paternal role. Therefore, this study examined the association of implicit motives and fathers’ perceived constraint due to fatherhood. Furthermore, we explored their relation to fathers’ life satisfaction. Participants were fathers with biological children (N = 276. They were asked to write picture stories, which were then coded for implicit affiliation and power motives. Perceived constraint and life satisfaction were assessed on a visual analog scale. A higher implicit need for affiliation was significantly associated with lower perceived constraint, whereas the implicit need for power had the opposite effect. Perceived constraint had a negative influence on life satisfaction. Structural equation modeling revealed significant indirect effects of implicit affiliation and power motives on life satisfaction mediated by perceived constraint. Our findings indicate that men with a higher implicit need for affiliation experience less constraint due to fatherhood, resulting in higher life satisfaction. The implicit need for power, however, results in more perceived constraint and is related to decreased life satisfaction.

Diffusion Processes Satisfying a Conservation Law Constraint

Directory of Open Access Journals (Sweden)

J. Bakosi

2014-01-01

Full Text Available We investigate coupled stochastic differential equations governing N nonnegative continuous random variables that satisfy a conservation principle. In various fields a conservation law requires a set of fluctuating variables to be nonnegative and (if appropriately normalized sum to one. As a result, any stochastic differential equation model to be realizable must not produce events outside of the allowed sample space. We develop a set of constraints on the drift and diffusion terms of such stochastic models to ensure that both the nonnegativity and the unit-sum conservation law constraints are satisfied as the variables evolve in time. We investigate the consequences of the developed constraints on the Fokker-Planck equation, the associated system of stochastic differential equations, and the evolution equations of the first four moments of the probability density function. We show that random variables, satisfying a conservation law constraint, represented by stochastic diffusion processes, must have diffusion terms that are coupled and nonlinear. The set of constraints developed enables the development of statistical representations of fluctuating variables satisfying a conservation law. We exemplify the results with the bivariate beta process and the multivariate Wright-Fisher, Dirichlet, and Lochner’s generalized Dirichlet processes.

NULIFE - Project CABINET. RPV Assessment under Consideration of Constraint and Warm Pre-Stress Effects

International Nuclear Information System (INIS)

Obermeier, F.; Nicak, Tomas; Keim, Elisabeth; Fekete, Tamas; Scibetta, Marc; Planman, Tapio; Laukkanen, Anssi; Carcia, Carlos Cueto-Felgueroso; Sattari-Far, Iradj

2012-01-01

At the moment, nuclear power plant regulators do not predominantly consider constraint and biaxial effects in their concepts for failure assessment of nuclear components. The warm pre-stressing (WPS) effect is only partly considered in some assessment procedures and codes. There is also a lack of a harmonized treatment of these effects in the safety assessment of European plants. This paper introduces the project CABINET (Constraint and Biaxial Loading Effects and their Interactions Considering Thermal Transients) which is a collaborative project under the EU's Network of Excellence NULIFE. The overall objective of CABINET is to investigate and understand constraint, biaxial loading and WPS effects in terms of a clearly defined application window, especially in the light of long term operation. The focus lies on already available experimental data and methodologies. The intention is to provide recommendations for a harmonized application of those effects in European nuclear safety assessment. The possibility to include different level of analysis depending on input data and acceptance of National Regulatory Body is also being evaluated. Although the CABINET project is not completed yet, it has been found that it is possible to rationalize the different existing codes. (author)

Route constraints model based on polychromatic sets

Science.gov (United States)

Yin, Xianjun; Cai, Chao; Wang, Houjun; Li, Dongwu

2018-03-01

With the development of unmanned aerial vehicle (UAV) technology, the fields of its application are constantly expanding. The mission planning of UAV is especially important, and the planning result directly influences whether the UAV can accomplish the task. In order to make the results of mission planning for unmanned aerial vehicle more realistic, it is necessary to consider not only the physical properties of the aircraft, but also the constraints among the various equipment on the UAV. However, constraints among the equipment of UAV are complex, and the equipment has strong diversity and variability, which makes these constraints difficult to be described. In order to solve the above problem, this paper, referring to the polychromatic sets theory used in the advanced manufacturing field to describe complex systems, presents a mission constraint model of UAV based on polychromatic sets.

ON Integrated Chance Constraints in ALM for Pension Funds

OpenAIRE

Youssouf A. F. Toukourou; Fran\\c{c}ois Dufresne

2015-01-01

We discuss the role of integrated chance constraints (ICC) as quantitative risk constraints in asset and liability management (ALM) for pension funds. We define two types of ICC: the one period integrated chance constraint (OICC) and the multiperiod integrated chance constraint (MICC). As their names suggest, the OICC covers only one period whereas several periods are taken into account with the MICC. A multistage stochastic linear programming model is therefore developed for this purpose and...

An Adaptive Evolutionary Algorithm for Traveling Salesman Problem with Precedence Constraints

Directory of Open Access Journals (Sweden)

Jinmo Sung

2014-01-01

Full Text Available Traveling sales man problem with precedence constraints is one of the most notorious problems in terms of the efficiency of its solution approach, even though it has very wide range of industrial applications. We propose a new evolutionary algorithm to efficiently obtain good solutions by improving the search process. Our genetic operators guarantee the feasibility of solutions over the generations of population, which significantly improves the computational efficiency even when it is combined with our flexible adaptive searching strategy. The efficiency of the algorithm is investigated by computational experiments.

Constraints and Ambiguity

DEFF Research Database (Denmark)

Dove, Graham; Biskjær, Michael Mose; Lundqvist, Caroline Emilie

2017-01-01

groups of students building three models each. We studied groups building with traditional plastic bricks and also using a digital environment. The building tasks students undertake, and our subsequent analysis, are informed by the role constraints and ambiguity play in creative processes. Based...

QCD unitarity constraints on Reggeon Field Theory

Energy Technology Data Exchange (ETDEWEB)

Kovner, Alex [Physics Department, University of Connecticut,2152 Hillside Road, Storrs, CT 06269 (United States); Levin, Eugene [Departemento de Física, Universidad Técnica Federico Santa María,and Centro Científico-Tecnológico de Valparaíso,Avda. Espana 1680, Casilla 110-V, Valparaíso (Chile); Department of Particle Physics, Tel Aviv University,Tel Aviv 69978 (Israel); Lublinsky, Michael [Physics Department, Ben-Gurion University of the Negev,Beer Sheva 84105 (Israel); Physics Department, University of Connecticut,2152 Hillside Road, Storrs, CT 06269 (United States)

2016-08-04

We point out that the s-channel unitarity of QCD imposes meaningful constraints on a possible form of the QCD Reggeon Field Theory. We show that neither the BFKL nor JIMWLK nor Braun’s Hamiltonian satisfy the said constraints. In a toy, zero transverse dimensional case we construct a model that satisfies the analogous constraint and show that at infinite energy it indeed tends to a “black disk limit' as opposed to the model with triple Pomeron vertex only, routinely used as a toy model in the literature.

QCD unitarity constraints on Reggeon Field Theory

International Nuclear Information System (INIS)

Kovner, Alex; Levin, Eugene; Lublinsky, Michael

2016-01-01

We point out that the s-channel unitarity of QCD imposes meaningful constraints on a possible form of the QCD Reggeon Field Theory. We show that neither the BFKL nor JIMWLK nor Braun’s Hamiltonian satisfy the said constraints. In a toy, zero transverse dimensional case we construct a model that satisfies the analogous constraint and show that at infinite energy it indeed tends to a “black disk limit' as opposed to the model with triple Pomeron vertex only, routinely used as a toy model in the literature.

Use of dose constraints for occupational exposure

International Nuclear Information System (INIS)

Kaijage, Tunu

2015-02-01

The use of dose constraints for occupational exposure was reviewed in this project. The role of dose constraints as used in optimization of protection of workers was described. Different issues to be considered in application of the concept and challenges associated with their implementation were also discussed. The situation where dose constraints could be misinterpreted to dose limits is also explained as the two are clearly differentiated by the International Commission of Radiological Protection (ICRP) Publication 103. Moreover, recommendations to all parties responsible for protection and safety of workers were discussed. (au)

Accuracy Constraint Determination in Fixed-Point System Design

Directory of Open Access Journals (Sweden)

Serizel R

2008-01-01

Full Text Available Most of digital signal processing applications are specified and designed with floatingpoint arithmetic but are finally implemented using fixed-point architectures. Thus, the design flow requires a floating-point to fixed-point conversion stage which optimizes the implementation cost under execution time and accuracy constraints. This accuracy constraint is linked to the application performances and the determination of this constraint is one of the key issues of the conversion process. In this paper, a method is proposed to determine the accuracy constraint from the application performance. The fixed-point system is modeled with an infinite precision version of the system and a single noise source located at the system output. Then, an iterative approach for optimizing the fixed-point specification under the application performance constraint is defined and detailed. Finally the efficiency of our approach is demonstrated by experiments on an MP3 encoder.

Theory of constraints: A state-of-art review

Directory of Open Access Journals (Sweden)

Maryam Orouji

2015-11-01

Full Text Available The theory of constraints (TOC is a management tool, which considers any manageable system as being limited in reaching more of its objectives by some constraints. According to TOC, there is always, at least, one single constraint, and TOC implements a concentrating process to detect the constraint and restructure the remaining of the organization around it. This paper presents an overview of different perspectives of TOC and its implementation in different industries such as project management, quality management, outsourcing, product mix, make-to-buy, accounting, banking and health care, etc. The results indicate that the method has been extensively implemented in different areas of accounting.

Advanced Hard Real-Time Operating System, the Maruti Project. Part 2.

Science.gov (United States)

1997-01-01

Real - Time Operating System , The Maruti Project DASG-60-92-C-0055 5b. Program Element # 62301E 6. Author(s...The maruti hard real - time " operating system . A CM SIGOPS, Operating Systems Review. 23:90-106, July 1989. 254 !1 110) C. L. Liu and J. Layland...February 14, 1995 Abstract The Maruti Real - Time Operating System was developed for applications that must meet hard real-time constraints. In order

Process for integrating surface drainage constraints on mine planning

Energy Technology Data Exchange (ETDEWEB)

Sawatsky, L.F; Ade, F.L.; McDonald, D.M.; Pullman, B.J. [Golder Associates Ltd., Calgary, AB (Canada)

2009-07-01

Surface drainage for mine closures must be considered during all phases of mine planning and design in order to minimize environmental impacts and reduce costs. This paper discussed methods of integrating mine drainage criteria and associated mine planning constraints into the mine planning process. Drainage constraints included stream diversions; fish compensation channels; collection receptacles for the re-use of process water; separation of closed circuit water from fresh water; and the provision of storage ponds. The geomorphic approach replicated the ability of natural channels to respond to local and regional changes in hydrology as well as channel disturbances from extreme flood events, sedimentation, debris, ice jams, and beaver activity. The approach was designed to enable a sustainable system and provide conveyance capacity for extreme floods without spillage to adjacent watersheds. Channel dimensions, bank and bed materials, sediment loads, bed material supplies and the hydrologic conditions of the analogue stream were considered. Hydrologic analyses were conducted to determine design flood flow. Channel routes, valley slopes, sinuosity, width, and depth were established. It was concluded that by incorporating the geomorphic technique, mine operators and designers can construct self-sustaining drainage systems that require little or no maintenance in the long-term. 7 refs.

Latin hypercube sampling with inequality constraints

International Nuclear Information System (INIS)

Iooss, B.; Petelet, M.; Asserin, O.; Loredo, A.

2010-01-01

In some studies requiring predictive and CPU-time consuming numerical models, the sampling design of the model input variables has to be chosen with caution. For this purpose, Latin hypercube sampling has a long history and has shown its robustness capabilities. In this paper we propose and discuss a new algorithm to build a Latin hypercube sample (LHS) taking into account inequality constraints between the sampled variables. This technique, called constrained Latin hypercube sampling (cLHS), consists in doing permutations on an initial LHS to honor the desired monotonic constraints. The relevance of this approach is shown on a real example concerning the numerical welding simulation, where the inequality constraints are caused by the physical decreasing of some material properties in function of the temperature. (authors)

Sports science needs more interdisciplinary, constraints-led research programmes: The case of water safety in New Zealand.

Science.gov (United States)

Button, C; Croft, J L

2017-12-01

In the lead article of this special issue, Paul Glazier proposes that Newell's constraints model has the potential to contribute to a grand unified theory of sports performance in that it can help to integrate the disciplinary silos that have typically operated in isolation in sports and exercise science. With a few caveats discussed in this commentary, we agree with Glazier's proposal. However, his ideas suggest that there is a need to demonstrate explicitly how such an integration might occur within applied scientific research. To help fill this perceived 'gap' and thereby illustrate the value of adopting a constraints-led approach, we offer an example of our own interdisciplinary research programme. We believe our research on water safety is ideally suited to this task due to the diverse range of interacting constraints present and as such provides a tangible example of how this approach can unify different disciplinary perspectives examining an important aspect of sport performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Medical image segmentation by means of constraint satisfaction neural network

International Nuclear Information System (INIS)

Chen, C.T.; Tsao, C.K.; Lin, W.C.

1990-01-01

This paper applies the concept of constraint satisfaction neural network (CSNN) to the problem of medical image segmentation. Constraint satisfaction (or constraint propagation), the procedure to achieve global consistency through local computation, is an important paradigm in artificial intelligence. CSNN can be viewed as a three-dimensional neural network, with the two-dimensional image matrix as its base, augmented by various constraint labels for each pixel. These constraint labels can be interpreted as the connections and the topology of the neural network. Through parallel and iterative processes, the CSNN will approach a solution that satisfies the given constraints thus providing segmented regions with global consistency

The Relationship between Leisure Constraints, Constraint Negotiation Strategies and Facilitators with Recreational Sport Activity Participation of College Students

Science.gov (United States)

Kocak, Funda

2017-01-01

The aim of this study is to determine the constraints in participating the leisure activities for college students, the strategies of negotiation regarding these constraints and the relationship between the facilitators and activity participation. The population of the study consists of currently registered students from Ankara University.…

Reconciling Scientific Aspirations and Engineering Constraints for a Lunar Mission via Hyperdimensional Interpolation

Science.gov (United States)

Weisbin, Charles R.; Clark, Pamela; Elfes, Alberto; Smith, Jeffrey H.; Mrozinski, Joseph; Adumitroaie, Virgil; Hua, Hook; Shelton, Kacie; Lincoln, William; Silberg, Robert

2010-01-01

Virtually every NASA space-exploration mission represents a compromise between the interests of two expert, dedicated, but very different communities: scientists, who want to go quickly to the places that interest them most and spend as much time there as possible conducting sophisticated experiments, and the engineers and designers charged with maximizing the probability that a given mission will be successful and cost-effective. Recent work at NASA's Jet Propulsion Laboratory (JPL) seeks to enhance communication between these two groups, and to help them reconcile their interests, by developing advanced modeling capabilities with which they can analyze the achievement of science goals and objectives against engineering design and operational constraints. The analyses conducted prior to this study have been point-design driven. Each analysis has been of one hypothetical case which addresses the question: Given a set of constraints, how much science can be done? But the constraints imposed by the architecture team-e.g., rover speed, time allowed for extravehicular activity (EVA), number of sites at which science experiments are to be conducted- are all in early development and carry a great deal of uncertainty. Variations can be incorporated into the analysis, and indeed that has been done in sensitivity studies designed to see which constraint variations have the greatest impact on results. But if a very large number of variations can be analyzed all at once, producing a table that includes virtually the entire trade space under consideration, then we have a tool that enables scientists and mission architects to ask the inverse question: For a given desired level of science (or any other objective), what is the range of constraints that would be needed? With this tool, mission architects could determine, for example, what combinations of rover speed, EVA duration, and other constraints produce the desired results. Further, this tool would help them identify which

Multiobjective Optimization Modeling Approach for Multipurpose Single Reservoir Operation

Directory of Open Access Journals (Sweden)

Iosvany Recio Villa

2018-04-01

Full Text Available The water resources planning and management discipline recognizes the importance of a reservoir’s carryover storage. However, mathematical models for reservoir operation that include carryover storage are scarce. This paper presents a novel multiobjective optimization modeling framework that uses the constraint-ε method and genetic algorithms as optimization techniques for the operation of multipurpose simple reservoirs, including carryover storage. The carryover storage was conceived by modifying Kritsky and Menkel’s method for reservoir design at the operational stage. The main objective function minimizes the cost of the total annual water shortage for irrigation areas connected to a reservoir, while the secondary one maximizes its energy production. The model includes operational constraints for the reservoir, Kritsky and Menkel’s method, irrigation areas, and the hydropower plant. The study is applied to Carlos Manuel de Céspedes reservoir, establishing a 12-month planning horizon and an annual reliability of 75%. The results highly demonstrate the applicability of the model, obtaining monthly releases from the reservoir that include the carryover storage, degree of reservoir inflow regulation, water shortages in irrigation areas, and the energy generated by the hydroelectric plant. The main product is an operational graph that includes zones as well as rule and guide curves, which are used as triggers for long-term reservoir operation.

Extended Set Constraints and Tree Grammar Abstraction of Programs

DEFF Research Database (Denmark)

Rosendahl, Mads; Gallagher, John Patrick

2011-01-01

Set constraints are relations between sets of ground terms or trees. This paper presents two main contributions: firstly we consider an extension of the systems of set constraints to include a tuple constructor, and secondly we construct a simplified solution procedure for set constraints. We...

Neural Based Tabu Search method for solving unit commitment problem with cooling-banking constraints

Directory of Open Access Journals (Sweden)

Rajan Asir Christober Gnanakkan Charles

2009-01-01

Full Text Available This paper presents a new approach to solve short-term unit commitment problem (UCP using Neural Based Tabu Search (NBTS with cooling and banking constraints. The objective of this paper is to find the generation scheduling such that the total operating cost can be minimized, when subjected to a variety of constraints. This also means that it is desirable to find the optimal generating unit commitment in the power system for next H hours. A 7-unit utility power system in India demonstrates the effectiveness of the proposed approach; extensive studies have also been performed for different IEEE test systems consist of 10, 26 and 34 units. Numerical results are shown to compare the superiority of the cost solutions obtained using the Tabu Search (TS method, Dynamic Programming (DP and Lagrangian Relaxation (LR methods in reaching proper unit commitment.

Origin of constraints in relativistic classical Hamiltonian dynamics

International Nuclear Information System (INIS)

Mallik, S.; Hugentobler, E.

1979-01-01

We investigate the null-plane or the front form of relativistic classical Hamiltonian dynamics as proposed by Dirac and developed by Leutwyler and Stern. For systems of two spinless particles we show that the algebra of Poincare generators is equivalent to describing dynamics in terms of two covariant constraint equations, the Poisson bracket of the two constraints being weakly zero. The latter condition is solved for certain simple forms of constraints

Energy conservation aircraft design and operational procedures

Energy Technology Data Exchange (ETDEWEB)

Poisson-Quinton, P.

1978-01-01

The paper reviews studies associated with improved fuel efficiency. Several aircraft design concepts are described including: (1) increases in aerodynamic efficiency through decreased friction drag, parasitic drag, and drag due to lift, (2) structural efficiency and the implementation of composite materials, (3) active control technology, (4) the optimization of airframe-engine integration, and (5) VTOL and STOL concepts. Consideration is also given to operational procedures associated with flight management, terminal-area operations, and the influence of environmental noise constraints on fuel economy.

Short-term optimal operation of Three-gorge and Gezhouba cascade hydropower stations in non-flood season with operation rules from data mining

International Nuclear Information System (INIS)

Ma Chao; Lian Jijian; Wang Junna

2013-01-01

Highlights: ► Short-term optimal operation of Three-gorge and Gezhouba hydropower stations was studied. ► Key state variable and exact constraints were proposed to improve numerical model. ► Operation rules proposed were applied in population initiation step for faster optimization. ► Culture algorithm with difference evolution was selected as optimization method. ► Model and method proposed were verified by case study with feasible operation solutions. - Abstract: Information hidden in the characteristics and relationship data of a cascade hydropower stations can be extracted by data-mining approaches to be operation rules and optimization support information. In this paper, with Three-gorge and Gezhouba cascade hydropower stations as an example, two operation rules are proposed due to different operation efficiency of water turbines and tight water volume and hydraulic relationship between two hydropower stations. The rules are applied to improve optimization model with more exact decision and state variables and constraints. They are also used in the population initiation step to develop better individuals with culture algorithm with differential evolution as an optimization method. In the case study, total feasible population and the best solution based on an initial population with an operation rule can be obtained with a shorter computation time than that of a pure random initiated population. Amount of electricity generation in a dispatch period with an operation rule also increases with an average increase rate of 0.025%. For a fixed water discharge process of Three-gorge hydropower station, there is a better rule to decide an operation plan of Gezhouba hydropower station in which total hydraulic head for electricity generation is optimized and distributed with inner-plant economic operation considered.

Einstein constraints in the Yang-Mills form

International Nuclear Information System (INIS)

Ashtekar, A.

1987-01-01

It is pointed out that constraints of Einstein's theory play a powerful role in both classical and quantum theory because they generate motions in spacetime, rather than in an internal space. New variables are then introduced on the Einstein phase space in terms of which constraints simplify considerably. In particular, the use of these variables enables one to imbed the constraint surface of Einstein's theory into that of Yang-Mills. The imbedding suggests new lines of attack to a number of problems in classical and quantum gravity and provides new concepts and tools to investigate the microscopic structure of space-time geometry

Non-technical constraints to eradication: the Italian experience.

Science.gov (United States)

Moda, Giuliana

2006-02-25

Although technical constraints to eradication of bovine tuberculosis are well-recognised, non-technical constraints can also delay progress towards eradication, leading to inefficiency and increased programme costs. This paper seeks to analyse the main non-technical constraints that can interfere with the successful implementation of tuberculosis eradication plans, based on experiences from an area of high tuberculosis prevalence in Regione Piemonte, Italy. The main social and economic constraints faced in the past 20 years are reviewed, including a social reluctance to recognise the importance of seeking eradication as the goal of disease control, effective communication of technical issues, the training and the organization of veterinary services, the relationship between the regional authority and farmers and their representatives, and data management and epidemiological reporting. The paper analyses and discusses the solutions that were applied in Regione Piemonte and the benefits that were obtained. Tuberculosis eradication plans are one of the most difficult tasks of the Veterinary Animal Health Services, and non-technical constraints must be considered when progress towards eradication is less than expected. Organizational and managerial resources can help to overcome social or economic obstacles, provided the veterinary profession is willing to address technical, but also non-technical, constraints to eradication.

PLZT thermal/flash protective goggles: device concepts and constraints

International Nuclear Information System (INIS)

Cutchen, J.T.

1979-01-01

In 1975 Sandia Laboratories began the design and development of PLZT Goggles for the US Air Force to provide protection from temporary flashblindness and permanent retinal burns caused by the brilliant flash of nuclear explosions. The user requirements, system and physical constraints, and use/storage environments were all considered in arriving at the final design goals. When the program began, there was no industrial capability to manufacture large-aperture PLZT materials or bonded lens assemblies. The technology has been established from a laboratory baseline in a brief period, and operational testing and evaluation by the Air Force has been completed. The goggles, identified as the EEU-2/P,, are now in production

Economic/operational advantages of top drive installations

Energy Technology Data Exchange (ETDEWEB)

Brouse, M. [Tesco Drilling Technology, Houston, TX (United States)

1996-10-01

This article addresses specific types of drilling operations, procedures and techniques associated with top drive drilling that create selected and/or specific economic opportunities and justifications for using a rental top drive. Types of drilling operations and/or wells that commonly justify top drive drilling described here include: drilling through sloughing or swelling formations; drilling extended reach, high angle and/or horizontal wells; drilling underbalanced through normal and subnormal formations; and wells with high daily operating costs, time constraints, i.e., days vs. depth, and/or safety and environmental concerns. Top drives, of course, are not justified for every drilling operation. Here, the discussion indicates some situations where portable systems may be applicable.

A Solution Approach to Assembly Line Balancing Problem With Task Related Constraints and an Application At An Enterprise

Directory of Open Access Journals (Sweden)

Serkan Altuntaş

2010-01-01

Full Text Available Occasionally certain tasks in an assembly line balancing problem are required to be kept together due to some specific reasons. These tasks are attained to the same work stations. Such problems are called as 'Assembly Line Balancing Problem with Task Related Constraints (ALBTRC'. Certain situations like awkward product construction, simultaneous operations or specific requirements leading to zoning and positional constraints like utilization of common resources as tools, jigs and fixtures are implemented thanks to these supplementary constraints. Additionally, materials handling and tooling costs, distances, set-up and lead times are also reduced. Literature on ALBTRC seems quite rare compared to Classical Line Balancing papers, although ALBTRC is one of the common real life balancing problems. This study aimed to develop and implement a novel line balancing method for a manufacturing concern where known methods are impractical to employ due to some specific positional constraints. 'Largest Candidate Method' known as a simple but effective tool is modified for this purpose first. Then a thorough 'method and time study' is conducted to get the necessary data to utilize that method. As a result, more efficient alternatives are generated and presented to decision maker.

Optimal Portfolio Choice with Wash Sale Constraints

DEFF Research Database (Denmark)

Astrup Jensen, Bjarne; Marekwica, Marcel

2011-01-01

We analytically solve the portfolio choice problem in the presence of wash sale constraints in a two-period model with one risky asset. Our results show that wash sale constraints can heavily affect portfolio choice of investors with unrealized losses. The trading behavior of such investors...

Input and output constraints-based stabilisation of switched nonlinear systems with unstable subsystems and its application

Science.gov (United States)

Chen, Chao; Liu, Qian; Zhao, Jun

2018-01-01

This paper studies the problem of stabilisation of switched nonlinear systems with output and input constraints. We propose a recursive approach to solve this issue. None of the subsystems are assumed to be stablisable while the switched system is stabilised by dual design of controllers for subsystems and a switching law. When only dealing with bounded input, we provide nested switching controllers using an extended backstepping procedure. If both input and output constraints are taken into consideration, a Barrier Lyapunov Function is employed during operation to construct multiple Lyapunov functions for switched nonlinear system in the backstepping procedure. As a practical example, the control design of an equilibrium manifold expansion model of aero-engine is given to demonstrate the effectiveness of the proposed design method.

From elementary flux modes to elementary flux vectors: Metabolic pathway analysis with arbitrary linear flux constraints

Science.gov (United States)

Klamt, Steffen; Gerstl, Matthias P.; Jungreuthmayer, Christian; Mahadevan, Radhakrishnan; Müller, Stefan

2017-01-01

Elementary flux modes (EFMs) emerged as a formal concept to describe metabolic pathways and have become an established tool for constraint-based modeling and metabolic network analysis. EFMs are characteristic (support-minimal) vectors of the flux cone that contains all feasible steady-state flux vectors of a given metabolic network. EFMs account for (homogeneous) linear constraints arising from reaction irreversibilities and the assumption of steady state; however, other (inhomogeneous) linear constraints, such as minimal and maximal reaction rates frequently used by other constraint-based techniques (such as flux balance analysis [FBA]), cannot be directly integrated. These additional constraints further restrict the space of feasible flux vectors and turn the flux cone into a general flux polyhedron in which the concept of EFMs is not directly applicable anymore. For this reason, there has been a conceptual gap between EFM-based (pathway) analysis methods and linear optimization (FBA) techniques, as they operate on different geometric objects. One approach to overcome these limitations was proposed ten years ago and is based on the concept of elementary flux vectors (EFVs). Only recently has the community started to recognize the potential of EFVs for metabolic network analysis. In fact, EFVs exactly represent the conceptual development required to generalize the idea of EFMs from flux cones to flux polyhedra. This work aims to present a concise theoretical and practical introduction to EFVs that is accessible to a broad audience. We highlight the close relationship between EFMs and EFVs and demonstrate that almost all applications of EFMs (in flux cones) are possible for EFVs (in flux polyhedra) as well. In fact, certain properties can only be studied with EFVs. Thus, we conclude that EFVs provide a powerful and unifying framework for constraint-based modeling of metabolic networks. PMID:28406903

Optimal capital stock and financing constraints

OpenAIRE

Saltari, Enrico; Giuseppe, Travaglini

2011-01-01

In this paper we show that financing constraints affect the optimal level of capital stock even when the financing constraint is ineffective. This happens when the firm rationally anticipates that access to external financing resources may be rationed in the future. We will show that with these expectations, the optimal investment policy is to invest less in any given period, thereby lowering the desired optimal capital stock in the long run.

Isocurvature constraints on portal couplings

Energy Technology Data Exchange (ETDEWEB)

Kainulainen, Kimmo; Nurmi, Sami; Vaskonen, Ville [Department of Physics, University of Jyväskylä, P.O.Box 35 (YFL), FI-40014 University of Jyväskylä (Finland); Tenkanen, Tommi; Tuominen, Kimmo, E-mail: kimmo.kainulainen@jyu.fi, E-mail: sami.t.nurmi@jyu.fi, E-mail: tommi.tenkanen@helsinki.fi, E-mail: kimmo.i.tuominen@helsinki.fi, E-mail: ville.vaskonen@jyu.fi [Department of Physics, University of Helsinki P.O. Box 64, FI-00014, Helsinki (Finland)

2016-06-01

We consider portal models which are ultraweakly coupled with the Standard Model, and confront them with observational constraints on dark matter abundance and isocurvature perturbations. We assume the hidden sector to contain a real singlet scalar s and a sterile neutrino ψ coupled to s via a pseudoscalar Yukawa term. During inflation, a primordial condensate consisting of the singlet scalar s is generated, and its contribution to the isocurvature perturbations is imprinted onto the dark matter abundance. We compute the total dark matter abundance including the contributions from condensate decay and nonthermal production from the Standard Model sector. We then use the Planck limit on isocurvature perturbations to derive a novel constraint connecting dark matter mass and the singlet self coupling with the scale of inflation: m {sub DM}/GeV ∼< 0.2λ{sub s}{sup 3/8} ( H {sub *}/10{sup 11} GeV){sup −3/2}. This constraint is relevant in most portal models ultraweakly coupled with the Standard Model and containing light singlet scalar fields.

Dimension-6 operator analysis of the CLIC sensitivity to new physics

International Nuclear Information System (INIS)

Ellis, John; Roloff, Philipp; Sanz, Verónica; You, Tevong

2017-01-01

We estimate the possible accuracies of measurements at the proposed CLIC e + e − collider of Higgs and W + W − production at centre-of-mass energies up to 3 TeV, incorporating also Higgsstrahlung projections at higher energies that had not been considered previously, and use them to explore the prospective CLIC sensitivities to decoupled new physics. We present the resulting constraints on the Wilson coefficients of dimension-6 operators in a model-independent approach based on the Standard Model effective field theory (SM EFT). The higher centre-of-mass energy of CLIC, compared to other projects such as the ILC and CEPC, gives it greater sensitivity to the coefficients of some of the operators we study. We find that CLIC Higgs measurements may be sensitive to new physics scales Λ=O(10) TeV for individual operators, reduced to O(1) TeV sensitivity for a global fit marginalising over the coefficients of all contributing operators. We give some examples of the corresponding prospective constraints on specific scenarios for physics beyond the SM, including stop quarks and the dilaton/radion.

Network Design with Node Degree Balance Constraints

DEFF Research Database (Denmark)

Pedersen, Michael Berliner; Crainic, Teodor Gabriel

This presentation discusses an extension to the network design model where there in addition to the flow conservation constraints also are constraints that require design conservation. This means that the number of arcs entering and leaving a node must be the same. As will be shown the model has ...

Constraint solving for direct manipulation of features

NARCIS (Netherlands)

Lourenco, D.; Oliveira, P.; Noort, A.; Bidarra, R.

2006-01-01

In current commercial feature modeling systems, support for direct manipulation of features is not commonly available. This is partly due to the strong reliance of such systems on constraints, but also to the lack of speed of current constraint solvers. In this paper, an approach to the optimization

Operators perspective

International Nuclear Information System (INIS)

Scragg, D.M.

1991-01-01

There are very few Energy from Municipal Waste processing plants in the U.K. Those which were built have usually been financed and operated by Local Authorities and are now in excess of 17 years old. The Environmental Protection Act and constraints on Public Sector spending have brought about fundamental changes in the approach taken to developing new schemes of this kind. The Public Sector and the Private Sector must work together. The investment in Mass Burning Incineration Schemes generating energy is high and the pressures to keep the waste disposal costs as low as possible mean that recovery of the investment needs to be spread over many years. For any Scheme to be successful and financially viable requires a long term commitment on the part of those involved. This paper sets out the key role which the Operating Contractor can play in this situation. (author)

Design Constraints for Liquid-Protected Divertors

International Nuclear Information System (INIS)

Shin, S.; Abdel-Khalik, S.I.; Yoda, M.

2005-01-01

Recent work on liquid-surface-protected plasma facing components has resulted in the establishment of operating windows for candidate liquids, as well as limits on the maximum allowable liquid surface temperature in order to limit plasma impurities from liquid evaporation. In this study, an additional constraint on the maximum allowable surface temperature gradient (i.e., heat flux gradient) has been quantified. Spatial variations in the wall and liquid surface temperatures are expected due to variations in the incident radiation and particle fluxes. Thermocapillary forces created by such temperature gradients can lead to film rupture and dry spot formation in regions of elevated local temperatures. Here, attention has been focused on ''non-flowing'' thin liquid films similar to those formed on the surface of porous wettedwall components. Future analyses will include the effects of macroscopic fluid motion, and MHD forces.A numerical model using the level contour reconstruction method was used to follow the evolution of the liquid free surface above a non-isothermal solid surface. The model was used to develop generalized charts for the maximum allowable spatial temperature gradients (i.e., the critical Marangoni number) as a function of the governing non-dimensional variables, viz. the Weber, Froude, and Prandtl numbers, and aspect ratio. Attention was focused on the asymptotic limit for thin liquid films (i.e., low aspect ratio) which provides a lower bound for the maximum allowable temperature gradients. Specific examples for lithium, Flibe, lithium-lead, tin, and gallium are presented. The generalized charts developed in this investigation will allow reactor designers to identify design windows for successful operation of liquid-protected plasma facing components for various coolants, film thicknesses, and operating conditions

Orbital Express mission operations planning and resource management using ASPEN

Science.gov (United States)

Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Daniel

2008-04-01

As satellite equipment and mission operations become more costly, the drive to keep working equipment running with less labor-power rises. Demonstrating the feasibility of autonomous satellite servicing was the main goal behind the Orbital Express (OE) mission. Like a tow-truck delivering gas to a car on the road, the "servicing" satellite of OE had to find the "client" from several kilometers away, connect directly to the client, and transfer fluid (or a battery) autonomously, while on earth-orbit. The mission met 100% of its success criteria, and proved that autonomous satellite servicing is now a reality for space operations. Planning the satellite mission operations for OE required the ability to create a plan which could be executed autonomously over variable conditions. As the constraints for execution could change weekly, daily, and even hourly, the tools used create the mission execution plans needed to be flexible and adaptable to many different kinds of changes. At the same time, the hard constraints of the plans needed to be maintained and satisfied. The Automated Scheduling and Planning Environment (ASPEN) tool, developed at the Jet Propulsion Laboratory, was used to create the schedule of events in each daily plan for the two satellites of the OE mission. This paper presents an introduction to the ASPEN tool, an overview of the constraints of the OE domain, the variable conditions that were presented within the mission, and the solution to operations that ASPEN provided. ASPEN has been used in several other domains, including research rovers, Deep Space Network scheduling research, and in flight operations for the NASA's Earth Observing One mission's EO1 satellite. Related work is discussed, as are the future of ASPEN and the future of autonomous satellite servicing.

Adaptive laser link reconfiguration using constraint propagation

Science.gov (United States)

Crone, M. S.; Julich, P. M.; Cook, L. M.

1993-01-01

This paper describes Harris AI research performed on the Adaptive Link Reconfiguration (ALR) study for Rome Lab, and focuses on the application of constraint propagation to the problem of link reconfiguration for the proposed space based Strategic Defense System (SDS) Brilliant Pebbles (BP) communications system. According to the concept of operations at the time of the study, laser communications will exist between BP's and to ground entry points. Long-term links typical of RF transmission will not exist. This study addressed an initial implementation of BP's based on the Global Protection Against Limited Strikes (GPALS) SDI mission. The number of satellites and rings studied was representative of this problem. An orbital dynamics program was used to generate line-of-site data for the modeled architecture. This was input into a discrete event simulation implemented in the Harris developed COnstraint Propagation Expert System (COPES) Shell, developed initially on the Rome Lab BM/C3 study. Using a model of the network and several heuristics, the COPES shell was used to develop the Heuristic Adaptive Link Ordering (HALO) Algorithm to rank and order potential laser links according to probability of communication. A reduced set of links based on this ranking would then be used by a routing algorithm to select the next hop. This paper includes an overview of Constraint Propagation as an Artificial Intelligence technique and its embodiment in the COPES shell. It describes the design and implementation of both the simulation of the GPALS BP network and the HALO algorithm in COPES. This is described using a 59 Data Flow Diagram, State Transition Diagrams, and Structured English PDL. It describes a laser communications model and the heuristics involved in rank-ordering the potential communication links. The generation of simulation data is described along with its interface via COPES to the Harris developed View Net graphical tool for visual analysis of communications

Constraint processing in our extensible language for cooperative imaging system

Science.gov (United States)

Aoki, Minoru; Murao, Yo; Enomoto, Hajime

1996-02-01

The extensible WELL (Window-based elaboration language) has been developed using the concept of common platform, where both client and server can communicate with each other with support from a communication manager. This extensible language is based on an object oriented design by introducing constraint processing. Any kind of services including imaging in the extensible language is controlled by the constraints. Interactive functions between client and server are extended by introducing agent functions including a request-respond relation. Necessary service integrations are satisfied with some cooperative processes using constraints. Constraints are treated similarly to data, because the system should have flexibilities in the execution of many kinds of services. The similar control process is defined by using intentional logic. There are two kinds of constraints, temporal and modal constraints. Rendering the constraints, the predicate format as the relation between attribute values can be a warrant for entities' validity as data. As an imaging example, a processing procedure of interaction between multiple objects is shown as an image application for the extensible system. This paper describes how the procedure proceeds in the system, and that how the constraints work for generating moving pictures.

Direct and indirect constraints on CP-violating Higgs-quark and Higgs-gluon interactions

International Nuclear Information System (INIS)

Chien, Y.T.; Cirigliano, V.; Dekens, W.; Vries, J. de; Mereghetti, E.

2016-01-01

We investigate direct and indirect constraints on the complete set of anomalous CP-violating Higgs couplings to quarks and gluons originating from dimension-6 operators, by studying their signatures at the LHC and in electric dipole moments (EDMs). We show that existing uncertainties in hadronic and nuclear matrix elements have a significant impact on the interpretation of EDM experiments, and we quantify the improvements needed to fully exploit the power of EDM searches. Currently, the best bounds on the anomalous CP-violating Higgs interactions come from a combination of EDM measurements and the data from LHC Run 1. We argue that Higgs production cross section and branching ratios measurements at the LHC Run 2 will not improve the constraints significantly. On the other hand, the bounds on the couplings scale roughly linearly with EDM limits, so that future theoretical and experimental EDM developments can have a major impact in pinning down interactions of the Higgs.

Adaptive control of a quadrotor aerial vehicle with input constraints and uncertain parameters

Science.gov (United States)

Tran, Trong-Toan; Ge, Shuzhi Sam; He, Wei

2018-05-01

In this paper, we address the problem of adaptive bounded control for the trajectory tracking of a Quadrotor Aerial Vehicle (QAV) while the input saturations and uncertain parameters with the known bounds are simultaneously taken into account. First, to deal with the underactuated property of the QAV model, we decouple and construct the QAV model as a cascaded structure which consists of two fully actuated subsystems. Second, to handle the input constraints and uncertain parameters, we use a combination of the smooth saturation function and smooth projection operator in the control design. Third, to ensure the stability of the overall system of the QAV, we develop the technique for the cascaded system in the presence of both the input constraints and uncertain parameters. Finally, the region of stability of the closed-loop system is constructed explicitly, and our design ensures the asymptotic convergence of the tracking errors to the origin. The simulation results are provided to illustrate the effectiveness of the proposed method.

Model predictive control-based scheduler for repetitive discrete event systems with capacity constraints

Directory of Open Access Journals (Sweden)

Hiroyuki Goto

2013-07-01

Full Text Available A model predictive control-based scheduler for a class of discrete event systems is designed and developed. We focus on repetitive, multiple-input, multiple-output, and directed acyclic graph structured systems on which capacity constraints can be imposed. The target system’s behaviour is described by linear equations in max-plus algebra, referred to as state-space representation. Assuming that the system’s performance can be improved by paying additional cost, we adjust the system parameters and determine control inputs for which the reference output signals can be observed. The main contribution of this research is twofold, 1: For systems with capacity constraints, we derived an output prediction equation as functions of adjustable variables in a recursive form, 2: Regarding the construct for the system’s representation, we improved the structure to accomplish general operations which are essential for adjusting the system parameters. The result of numerical simulation in a later section demonstrates the effectiveness of the developed controller.

The role of the control room operator

International Nuclear Information System (INIS)

Williams, M.C.

A control room operator at an Ontario Hydro nuclear power plant operates a reactor-turbine unit according to approved procedures within imposed constraints to meet the objectives of the organization. A number of operating and administrative tasks make up this role. Control room operators spend approximately six percent of their time physically operating equipment exclusive of upset conditions, and another one percent operating in upset conditions. Testing occupies five percent of an operator's time. Operators must be trained to recognize the entire spectrum of inputs available to them and use them all effectively. Any change in system or unit state is always made according to an approved procedure. Extensive training is required; operators must be taught and pracised in what to do, and must know the reasons behind their actions. They are expected to memorize emergency procedures, to know when to consult operating procedures, and to have sufficient understanding and practice to perform these procedures reliably

NASA Extreme Environment Mission Operations: Science Operations Development for Human Exploration

Science.gov (United States)

Bell, Mary S.

2014-01-01

The purpose of NASA Extreme Environment Mission Operations (NEEMO) mission 16 in 2012 was to evaluate and compare the performance of a defined series of representative near-Earth asteroid (NEA) extravehicular activity (EVA) tasks under different conditions and combinations of work systems, constraints, and assumptions considered for future human NEA exploration missions. NEEMO 16 followed NASA's 2011 Desert Research and Technology Studies (D-RATS), the primary focus of which was understanding the implications of communication latency, crew size, and work system combinations with respect to scientific data quality, data management, crew workload, and crew/mission control interactions. The 1-g environment precluded meaningful evaluation of NEA EVA translation, worksite stabilization, sampling, or instrument deployment techniques. Thus, NEEMO missions were designed to provide an opportunity to perform a preliminary evaluation of these important factors for each of the conditions being considered. NEEMO 15 also took place in 2011 and provided a first look at many of the factors, but the mission was cut short due to a hurricane threat before all objectives were completed. ARES Directorate (KX) personnel consulted with JSC engineers to ensure that high-fidelity planetary science protocols were incorporated into NEEMO mission architectures. ARES has been collaborating with NEEMO mission planners since NEEMO 9 in 2006, successively building upon previous developments to refine science operations concepts within engineering constraints; it is expected to continue the collaboration as NASA's human exploration mission plans evolve.

Operations planning for Space Station Freedom - And beyond

Science.gov (United States)

Gibson, Stephen S.; Martin, Thomas E.; Durham, H. J.

1992-01-01

The potential of automated planning and electronic execution systems for enhancing operations on board Space Station Freedom (SSF) are discussed. To exploit this potential the Operations Planning and Scheduling Subsystem is being developed at the NASA Johnson Space Center. Such systems may also make valuable contributions to the operation of resource-constrained, long-duration space habitats of the future. Points that should be considered during the design of future long-duration manned space missions are discussed. Early development of a detailed operations concept as an end-to-end mission description offers a basis for iterative design evaluation, refinement, and option comparison, particularly when used with an advanced operations planning system capable of modeling the operations and resource constraints of the proposed designs.

Constraints in distortion-invariant target recognition system simulation

Science.gov (United States)

Iftekharuddin, Khan M.; Razzaque, Md A.

2000-11-01

Automatic target recognition (ATR) is a mature but active research area. In an earlier paper, we proposed a novel ATR approach for recognition of targets varying in fine details, rotation, and translation using a Learning Vector Quantization (LVQ) Neural Network (NN). The proposed approach performed segmentation of multiple objects and the identification of the objects using LVQNN. In this current paper, we extend the previous approach for recognition of targets varying in rotation, translation, scale, and combination of all three distortions. We obtain the analytical results of the system level design to show that the approach performs well with some constraints. The first constraint determines the size of the input images and input filters. The second constraint shows the limits on amount of rotation, translation, and scale of input objects. We present the simulation verification of the constraints using DARPA's Moving and Stationary Target Recognition (MSTAR) images with different depression and pose angles. The simulation results using MSTAR images verify the analytical constraints of the system level design.

Sustainability constraints on UK bioenergy development

International Nuclear Information System (INIS)

Thornley, Patricia; Upham, Paul; Tomei, Julia

2009-01-01

Use of bioenergy as a renewable resource is increasing in many parts of the world and can generate significant environmental, economic and social benefits if managed with due regard to sustainability constraints. This work reviews the environmental, social and economic constraints on key feedstocks for UK heat, power and transport fuel. Key sustainability constraints include greenhouse gas savings achieved for different fuels, land availability, air quality impacts and facility siting. Applying those constraints, we estimate that existing technologies would facilitate a sustainability constrained level of medium-term bioenergy/biofuel supply to the UK of 4.9% of total energy demand, broken down into 4.3% of heat demands, 4.3% of electricity, and 5.8% of transport fuel. This suggests that attempts to increase the supply above these levels could have counterproductive sustainability impacts in the absence of compensating technology developments or identification of additional resources. The barriers that currently prevent this level of supply being achieved have been analysed and classified. This suggests that the biggest policy impacts would be in stimulating the market for heat demand in rural areas, supporting feedstock prices in a manner that incentivised efficient use/maximum greenhouse gas savings and targeting investment capital that improves yield and reduces land-take.

Nonlinear Model Predictive Control with Constraint Satisfactions for a Quadcopter

Science.gov (United States)

Wang, Ye; Ramirez-Jaime, Andres; Xu, Feng; Puig, Vicenç

2017-01-01

This paper presents a nonlinear model predictive control (NMPC) strategy combined with constraint satisfactions for a quadcopter. The full dynamics of the quadcopter describing the attitude and position are nonlinear, which are quite sensitive to changes of inputs and disturbances. By means of constraint satisfactions, partial nonlinearities and modeling errors of the control-oriented model of full dynamics can be transformed into the inequality constraints. Subsequently, the quadcopter can be controlled by an NMPC controller with the updated constraints generated by constraint satisfactions. Finally, the simulation results applied to a quadcopter simulator are provided to show the effectiveness of the proposed strategy.

CBDS: Constraint-based diagnostic system for malfunction identification in the nuclear power plant

International Nuclear Information System (INIS)

Ha, J.

1992-01-01

Traditional rule-based diagnostic expert systems use the experience of experts in the form of rules that associate symptoms with underlying faults. A commonly recognized failing of such systems is their narrow range of expertise and their inability to recognize problems outside this range of expertise. A model base diagnostic system isolating malfunctioning components-CBDS, the Constraint based Diagnostic System-has been developed. Since the intended behavior of a device is more predictable than unintended behaviors (faults), a model based system using the intended behavior has a potential to diagnose unexpected malfunctions by considering faults as open-quotes anything other than the intended behavior.close quotes As a knowledge base, the CBDS generates and decomposes a constraint network based on the structure and behavior model, which are represented symbolically in algebraic equations. Behaviors of generic components are organized in a component model library. Once the library is available, actual domain knowledge can be represented by declaring component types and their connections. To capture various plant knowledge, the mixed model was developed which allow the use of different parameter types in one equation by defining various operators. The CBDS uses the general idea of model based diagnosis. It detects a discrepancy between observation and prediction using constraint propagation, which carriers and accumulates the assumptions when parameter values are deduced. When measured plant parameters are asserted into a constraint network and are propagated through the network, a discrepancy will be detected if there exists any malfunctioning component. The CBDS was tested in the Recirculation Flow Control System of a BWR, and has been shown to be able to diagnose unexpected events

Multi-objective demand side scheduling considering the operational safety of appliances

International Nuclear Information System (INIS)

Du, Y.F.; Jiang, L.; Li, Y.Z.; Counsell, J.; Smith, J.S.

2016-01-01

Highlights: • Operational safety of appliances is introduced in multi-objective scheduling. • Relationships between operational safety and other objectives are investigated. • Adopted Pareto approach is compared with Weigh and Constraint approaches. • Decision making of Pareto approach is proposed for final appliances’ scheduling. - Abstract: The safe operation of appliances is of great concern to users. The safety risk increases when the appliances are in operation during periods when users are not at home or when they are asleep. In this paper, multi-objective demand side scheduling is investigated with consideration to the appliances’ operational safety together with the electricity cost and the operational delay. The formulation of appliances’ operational safety is proposed based on users’ at-home status and awake status. Then the relationships between the operational safety and the other two objectives are investigated through the approach of finding the Pareto-optimal front. Moreover, this approach is compared with the Weigh and Constraint approaches. As the Pareto-optimal front consists of a set of optimal solutions, this paper proposes a method to make the final scheduling decision based on the relationships among the multiple objectives. Simulation results demonstrate that the operational safety is improved with the sacrifice of the electricity cost and the operational delay, and that the approach of finding the Pareto-optimal front is effective in presenting comprehensive optimal solutions of the multi-objective demand side scheduling.

Data reconciliation and optimal operation of a Catalytic naphtha reformer

Directory of Open Access Journals (Sweden)

Tore Lid

2008-10-01

Full Text Available The naphtha reforming process converts low-octane gasoline blending components to high-octane components for use in high-performance gasoline fuels. The reformer also has an important function as the producer of hydrogen to the refinery hydrotreaters. A process model based on a unit model structure, is used for estimation of the process condition using data reconciliation. Measurements are classified as redundant or non redundant and the model variables are classified as observable, barely observable or unobservable. The computed uncertainty of the measured and unmeasured variables shows that even if a variable is observable it may have a very large uncertainty and may thereby be practically unobservable. The process condition at 21 data points, sampled from two years of operation, was reconciled and used to optimize the process operation. There are large seasonal variations in the reformer product price and two operational cases are studied. In case 1, the product price is high and throughput is maximized with respect to process and product quality constraints. In case 2, the product price is low and the throughput is minimized with respect to a low constraint on the hydrogen production. Based on the characteristics of the optimal operation, a "self optimizing" control structure is suggested for each of the two operational cases.

BRST operator quantization of generally covariant gauge systems

International Nuclear Information System (INIS)

Ferraro, R.; Sforza, D.M.

1997-01-01

The BRST generator is realized as a Hermitian nilpotent operator for a finite-dimensional gauge system featuring a quadratic super-Hamiltonian and linear supermomentum constraints. As a result, the emerging ordering for the Hamiltonian constraint is not trivial, because the potential must enter the kinetic term in order to obtain a quantization invariant under scaling. Namely, BRST quantization does not lead to the curvature term used in the literature as a means to get that invariance. The inclusion of the potential in the kinetic term, far from being unnatural, is beautifully justified in light of the Jacobi's principle. copyright 1997 The American Physical Society

Pension fund's illiquid assets allocation under liquidity and capital constraints

OpenAIRE

Broeders, Dirk; Jansen, Kristy; Werker, Bas

2017-01-01

This paper empirically assesses the impact of liquidity and capital constraints on the allocation of defined benefit pension funds to illiquid assets. Liquidity constraints result from short-term pension payments and collateral requirements on derivatives. Capital constraints follow from the requirement to retain sufficient capital to absorb unexpected losses. Liability duration and hedging affect the allocation to illiquid assets through both these constraints. First, we find a hump-shaped i...

Operational cost minimization in cooling water systems

Directory of Open Access Journals (Sweden)

Castro M.M.

2000-01-01

Full Text Available In this work, an optimization model that considers thermal and hydraulic interactions is developed for a cooling water system. It is a closed loop consisting of a cooling tower unit, circulation pump, blower and heat exchanger-pipe network. Aside from process disturbances, climatic fluctuations are considered. Model constraints include relations concerning tower performance, air flowrate requirement, make-up flowrate, circulating pump performance, heat load in each cooler, pressure drop constraints and climatic conditions. The objective function is operating cost minimization. Optimization variables are air flowrate, forced water withdrawal upstream the tower, and valve adjustment in each branch. It is found that the most significant operating cost is related to electricity. However, for cooled water temperatures lower than a specific target, there must be a forced withdrawal of circulating water and further makeup to enhance the cooling tower capacity. Additionally, the system is optimized along the months. The results corroborate the fact that the most important variable on cooling tower performance is not the air temperature itself, but its humidity.

Understanding the leisure constraints of Hispanic-Americans in Northern Virginia: an exploratory analysis of constraints, socioeconomic status and acculturation

Science.gov (United States)

Edward F, II Byrne; Ellen B. Drogin Rodgers

2003-01-01

The purpose of this study is to investigate the constraints to use of outdoor recreation resources and participation in leisure activities among Hispanic restaurant workers in Northern Virginia; specifically, the relationship of socioeconomic status and acculturation to leisure constraints. The dramatic rate of increase of Hispanic-Americans, the group's low...

Self-Imposed Creativity Constraints

DEFF Research Database (Denmark)

Biskjaer, Michael Mose

2013-01-01

Abstract This dissertation epitomizes three years of research guided by the research question: how can we conceptualize creative self-binding as a resource in art and design processes? Concretely, the dissertation seeks to offer insight into the puzzling observation that highly skilled creative...... practitioners sometimes freely and intentionally impose rigid rules, peculiar principles, and other kinds of creative obstructions on themselves as a means to spur momentum in the process and reach a distinctly original outcome. To investigate this the dissertation is composed of four papers (Part II) framed...... of analysis. Informed by the insight that constraints both enable and restrain creative agency, the dissertation’s main contention is that creative self- binding may profitably be conceptualized as the exercise of self-imposed creativity constraints. Thus, the dissertation marks an analytical move from vague...

Distance Constraint Satisfaction Problems

Science.gov (United States)

Bodirsky, Manuel; Dalmau, Victor; Martin, Barnaby; Pinsker, Michael

We study the complexity of constraint satisfaction problems for templates Γ that are first-order definable in ({ Z}; {suc}), the integers with the successor relation. Assuming a widely believed conjecture from finite domain constraint satisfaction (we require the tractability conjecture by Bulatov, Jeavons and Krokhin in the special case of transitive finite templates), we provide a full classification for the case that Γ is locally finite (i.e., the Gaifman graph of Γ has finite degree). We show that one of the following is true: The structure Γ is homomorphically equivalent to a structure with a certain majority polymorphism (which we call modular median) and CSP(Γ) can be solved in polynomial time, or Γ is homomorphically equivalent to a finite transitive structure, or CSP(Γ) is NP-complete.

The operating room case-mix problem under uncertainty and nurses capacity constraints.

Science.gov (United States)

Yahia, Zakaria; Eltawil, Amr B; Harraz, Nermine A

2016-12-01

Surgery is one of the key functions in hospitals; it generates significant revenue and admissions to hospitals. In this paper we address the decision of choosing a case-mix for a surgery department. The objective of this study is to generate an optimal case-mix plan of surgery patients with uncertain surgery operations, which includes uncertainty in surgery durations, length of stay, surgery demand and the availability of nurses. In order to obtain an optimal case-mix plan, a stochastic optimization model is proposed and the sample average approximation method is applied. The proposed model is used to determine the number of surgery cases to be weekly served, the amount of operating rooms' time dedicated to each specialty and the number of ward beds dedicated to each specialty. The optimal case-mix selection criterion is based upon a weighted score taking into account both the waiting list and the historical demand of each patient category. The score aims to maximizing the service level of the operating rooms by increasing the total number of surgery cases that could be served. A computational experiment is presented to demonstrate the performance of the proposed method. The results show that the stochastic model solution outperforms the expected value problem solution. Additional analysis is conducted to study the effect of varying the number of ORs and nurses capacity on the overall ORs' performance.

Canonical and D-transformations in Theories with Constraints

OpenAIRE

Gitman, Dmitri M.

1995-01-01

A class class of transformations in a super phase space (we call them D-transformations) is described, which play in theories with second-class constraints the role of ordinary canonical transformations in theories without constraints.

Guiding rational reservoir flood operation using penalty-type genetic algorithm

Science.gov (United States)

Chang, Li-Chiu

2008-06-01

SummaryReal-time flood control of a multi-purpose reservoir should consider decreasing the flood peak stage downstream and storing floodwaters for future usage during typhoon seasons. This study proposes a reservoir flood control optimization model with linguistic description of requirements and existing regulations for rational operating decisions. The approach involves formulating reservoir flood operation as an optimization problem and using the genetic algorithm (GA) as a search engine. The optimizing formulation is expressed not only by mathematical forms of objective function and constraints, but also by no analytic expression in terms of parameters. GA is used to search a global optimum of a mixture of mathematical and nonmathematical formulations. Due to the great number of constraints and flood control requirements, it is difficult to reach a solution without violating constraints. To tackle this bottleneck, the proper penalty strategy for each parameter is proposed to guide the GA searching process. The proposed approach is applied to the Shihmen reservoir in North Taiwan for finding the rational release and desired storage as a case study. The hourly historical data sets of 29 typhoon events that have hit the area in last thirty years are investigated bye the proposed method. To demonstrate the effectiveness of the proposed approach, the simplex method was performed. The results demonstrated that a penalty-type genetic algorithm could effectively provide rational hydrographs to reduce flood damage during the flood operation and to increase final storage for future usages.

Scale hierarchy in Hořava-Lifshitz gravity: strong constraint from synchrotron radiation in the Crab Nebula.

Science.gov (United States)

Liberati, Stefano; Maccione, Luca; Sotiriou, Thomas P

2012-10-12

Hořava-Lifshitz gravity models contain higher-order operators suppressed by a characteristic scale, which is required to be parametrically smaller than the Planck scale. We show that recomputed synchrotron radiation constraints from the Crab Nebula suffice to exclude the possibility that this scale is of the same order of magnitude as the Lorentz breaking scale in the matter sector. This highlights the need for a mechanism that suppresses the percolation of Lorentz violation in the matter sector and is effective for higher-order operators as well.

The Issue of Unit Constraints and the Non-Confiscatory Electricity Market

DEFF Research Database (Denmark)

Haji Bashi, Mazaher; Rahmati, Iman; Bak, Claus Leth

2017-01-01

Security constraint unit commitment is devised to drive the generation unit schedule in a deregulated environment. Generation bids, transmission system constraints and generation unit constraints are thoroughly considered in this optimization problem. It is acceptable that the transmission system...... normal condition constraints may affect the economic opportunities of the generation companies in the electricity market. Transmission system limitations are the inherent limits of the market environment but this is not true for the generation unit constraints. It means that the generation unit...... constraint of a certain player should not affect the economic opportunities of the rivals. If this happen, generation units can claim to the electricity market regulatory board. In this paper the effect of generation unit constraint on the market outcome is discussed. A fair mechanism is introduced in which...

Pension fund's illiquid assets allocation under liquidity and capital constraints

NARCIS (Netherlands)

Broeders, Dirk; Jansen, Kristy; Werker, Bas

2017-01-01

This paper empirically assesses the impact of liquidity and capital constraints on the allocation of defined benefit pension funds to illiquid assets. Liquidity constraints result from short-term pension payments and collateral requirements on derivatives. Capital constraints follow from the

Effective constraint algebras with structure functions

International Nuclear Information System (INIS)

Bojowald, Martin; Brahma, Suddhasattwa

2016-01-01

This article presents the result that fluctuations and higher moments of a state, by themselves, do not imply quantum corrections in structure functions of constrained systems. Moment corrections are isolated from other types of quantum effects, such as factor-ordering choices and regularization, by introducing a new condition with two parts: (i) having a direct (or faithful) quantization of the classical structure functions, (ii) free of factor-ordering ambiguities. In particular, it is assumed that the classical constraints can be quantized in an anomaly free way, so that properties of the resulting constraint algebras can be derived. If the two-part condition is not satisfied, effective constraints can still be evaluated, but quantum effects may be stronger. Consequences for canonical quantum gravity, whose structure functions encode space–time structure, are discussed. In particular, deformed algebras found in models of loop quantum gravity provide reliable information even in the Planck regime. (paper)

WMAP constraints on the Cardassian model

International Nuclear Information System (INIS)

Sen, A.A.; Sen, S.

2003-01-01

We investigate the constraints on the Cardassian model using the recent results from the Wilkinson microwave anisotropy probe for the locations of the peaks of the cosmic microwave background (CMB) anisotropy spectrum. We find that the model is consistent with the recent observational data for a certain range of the model parameter n and the cosmological parameters. We find that the Cardassian model is favored compared to the ΛCDM model for a higher spectral index (n s ≅1) together with a lower value of the Hubble parameter h (h≤0.71). But for smaller values of n s , both ΛCDM and Cardassian models are equally favored. Also, irrespective of supernova constraints, CMB data alone predict the current acceleration of the Universe in this model. We have also studied the constraint on σ 8 , the rms density fluctuations at the 8h -1 Mpc scale

A combined constraint handling framework: an empirical study

DEFF Research Database (Denmark)

Si, Chengyong; Hu, Junjie; Lan, Tian

2017-01-01

This paper presents a new combined constraint handling framework (CCHF) for solving constrained optimization problems (COPs). The framework combines promising aspects of different constraint handling techniques (CHTs) in different situations with consideration of problem characteristics. In order...

Army Attack Aviation and Joint Air Operations: Doctrinal and Institutional Barriers

National Research Council Canada - National Science Library

Holmes, Sharon

2000-01-01

... operations in the Serbian province of Kosovo. Since political constraints precluded a ground option to resolve the conflict, the Supreme Allied Commander, Europe requested a wide range of aerospace assets to accomplish campaign objectives...

Constraint shapes convergence in tetrodotoxin-resistant sodium channels of snakes.

Science.gov (United States)

Feldman, Chris R; Brodie, Edmund D; Brodie, Edmund D; Pfrender, Michael E

2012-03-20

Natural selection often produces convergent changes in unrelated lineages, but the degree to which such adaptations occur via predictable genetic paths is unknown. If only a limited subset of possible mutations is fixed in independent lineages, then it is clear that constraint in the production or function of molecular variants is an important determinant of adaptation. We demonstrate remarkably constrained convergence during the evolution of resistance to the lethal poison, tetrodotoxin, in six snake species representing three distinct lineages from around the globe. Resistance-conferring amino acid substitutions in a voltage-gated sodium channel, Na(v)1.4, are clustered in only two regions of the protein, and a majority of the replacements are confined to the same three positions. The observed changes represent only a small fraction of the experimentally validated mutations known to increase Na(v)1.4 resistance to tetrodotoxin. These results suggest that constraints resulting from functional tradeoffs between ion channel function and toxin resistance led to predictable patterns of evolutionary convergence at the molecular level. Our data are consistent with theoretical predictions and recent microcosm work that suggest a predictable path is followed during an adaptive walk along a mutational landscape, and that natural selection may be frequently constrained to produce similar genetic outcomes even when operating on independent lineages.

Multi-AGV path planning with double-path constraints by using an improved genetic algorithm.

Directory of Open Access Journals (Sweden)

Zengliang Han

Full Text Available This paper investigates an improved genetic algorithm on multiple automated guided vehicle (multi-AGV path planning. The innovations embody in two aspects. First, three-exchange crossover heuristic operators are used to produce more optimal offsprings for getting more information than with the traditional two-exchange crossover heuristic operators in the improved genetic algorithm. Second, double-path constraints of both minimizing the total path distance of all AGVs and minimizing single path distances of each AGV are exerted, gaining the optimal shortest total path distance. The simulation results show that the total path distance of all AGVs and the longest single AGV path distance are shortened by using the improved genetic algorithm.

Optimal Power Flow Using Gbest-Guided Cuckoo Search Algorithm with Feedback Control Strategy and Constraint Domination Rule

Directory of Open Access Journals (Sweden)

Gonggui Chen

2017-01-01

Full Text Available The optimal power flow (OPF is well-known as a significant optimization tool for the security and economic operation of power system, and OPF problem is a complex nonlinear, nondifferentiable programming problem. Thus this paper proposes a Gbest-guided cuckoo search algorithm with the feedback control strategy and constraint domination rule which is named as FCGCS algorithm for solving OPF problem and getting optimal solution. This FCGCS algorithm is guided by the global best solution for strengthening exploitation ability. Feedback control strategy is devised to dynamically regulate the control parameters according to actual and specific feedback value in the simulation process. And the constraint domination rule can efficiently handle inequality constraints on state variables, which is superior to traditional penalty function method. The performance of FCGCS algorithm is tested and validated on the IEEE 30-bus and IEEE 57-bus example systems, and simulation results are compared with different methods obtained from other literatures recently. The comparison results indicate that FCGCS algorithm can provide high-quality feasible solutions for different OPF problems.

French experience in operating pressurized water reactor power stations. Ten years' operation of the Ardennes power station

International Nuclear Information System (INIS)

Teste du Bailler, A.; Vedrinne, J.F.

1978-01-01

In the paper the experience gained over ten years' operation of the Ardennes (Chooz) nuclear power station is summarized from the point of view of monitoring and control equipment. The reactor was the first pressurized water reactor to be installed in France; it is operated jointly by France and Belgium. The equipment, which in many cases consists of prototypes, was developed for industrial use and with the experience that has now been gained it is possible to evaluate its qualities and defects, the constraints which it imposes and the action that has to be taken in the future. (author)

Design with Nonlinear Constraints

KAUST Repository

Tang, Chengcheng

2015-01-01

. The first application is the design of meshes under both geometric and static constraints, including self-supporting polyhedral meshes that are not height fields. Then, with a formulation bridging mesh based and spline based representations, the application

Financial constraint and R&D investment: evidence from CIS

OpenAIRE

Tiwari, A.K.; Mohnen, P.; Palm, F.C.; Schim van der Loeff, S.

2007-01-01

Using direct information on financial constraints from questionnaires, rather than the commonly used balance sheet information, this paper presents evidence that, controlling for traditional factors as size, market share, cooperative arrangement, and expected profitability, financial constraints affect a firm's decision of how much to invest in R&D activities. Apart from these constraints, other hampering factors as market uncertainty and institutional bottlenecks, regulations and organizatio...

Constraints and Logic Programming in Grammars and Language Analysis

DEFF Research Database (Denmark)

Christiansen, Henning

2014-01-01

Constraints are an important notion in grammars and language analysis, and constraint programming techniques have been developed concurrently for solving a variety of complex problems. In this chapter we consider the synthesis of these branches into practical and effective methods for language...... methods that combine constraints with logic grammars such as Definite Clause Grammars and CHR Grammars, and show also a direct relationship to abductive reasoning....

Mobility and Position Error Analysis of a Complex Planar Mechanism with Redundant Constraints

Science.gov (United States)

Sun, Qipeng; Li, Gangyan

2018-03-01

Nowadays mechanisms with redundant constraints have been created and attracted much attention for their merits. The mechanism of the redundant constraints in a mechanical system is analyzed in this paper. A analysis method of Planar Linkage with a repetitive structure is proposed to get the number and type of constraints. According to the difference of applications and constraint characteristics, the redundant constraints are divided into the theoretical planar redundant constraints and the space-planar redundant constraints. And the calculation formula for the number of redundant constraints and type of judging method are carried out. And a complex mechanism with redundant constraints is analyzed of the influence about redundant constraints on mechanical performance. With the combination of theoretical derivation and simulation research, a mechanism analysis method is put forward about the position error of complex mechanism with redundant constraints. It points out the direction on how to eliminate or reduce the influence of redundant constraints.

Research on the Strategy of Motion Constraint-Aided ZUPT for the SINS Positioning System of a Shearer

Directory of Open Access Journals (Sweden)

Hai Yang

2017-11-01

Full Text Available The accurate measurement of position and orientation for shearers is a key technology in realizing an automated, fully-mechanized, coal mining face. Since Global Positioning System (GPS signal cannot arrive at the coal mine underground, wireless sensor network positioning system cannot operate stably in the coal mine; thus a strap-down inertial navigation system (SINS is used to measure the position and orientation of the shearer. Aiming at the problem of the SINS accumulative error, this paper proposes a positioning error correction method based on the motion constraint-aided SINS zero velocity updated (ZUPT model. First of all, a stationary state detection model of the shearer is built with median filter based on the acceleration and angular rate measured by the SINS. Secondly, the motion of the shearer is analyzed using coal mining technology, then the motion constraint model of the shearer is established. In addition, the alternate action between the motion constraint model and the ZUPT model is analyzed at the process of movement and cessation of the shearer, respectively; hence, the motion constraint-aided SINS ZUPT model is built. Finally, by means of the experimental platform of the SINS for the shearer, the experimental results show that the maximum position error with the positioning model proposed in this paper is 1.6 m in 180 s, and increases by 92.0% and 88.1% compared with the single motion constraint model and single ZUPT model, respectively. It can then restrain the accumulative error of the SINS effectively.

India's nuclear power programme and constraints encountered in its implementation

International Nuclear Information System (INIS)

Sethna, H.N.; Srinivasan, M.R.

1977-01-01

Nuclear power development in India is based on natural-uranium fuelled pressurized heavy-water reactors. However, to acquire early experience in operation and maintenance of nuclear power stations, India's first atomic power station comprised two units of boiling-water reactors. Subsequent nuclear power stations currently in operation or under construction employ natural-uranium heavy-water reactors and each is a two-reactor installation. While the first two nuclear power stations employ reactors of 200MW capacity, the subsequent stations employ reactors with an output of 235MW. Heavy-water reactors of 500-MW capacity are foreseen for the period beyond 1985. The first nuclear power station was essentially fully imported: the second, which employs heavy-water reactors, has already made a significant contribution of equipment manufactured in India. For the third nuclear power station and for the subsequent one, practically all equipment is being manufactured indigenously. The nuclear power station at Narora is in a seismic region and hence the design is substantially more advanced than those at the earlier sites and also employs concepts which will be used in the 500-MW reactors. Efforts are being made in India to integrate power generation systems into larger regional grids and eventually into a national grid; however, the distributed nature of power generation at present and other infrastructural limitations still favour small and medium-size plants only. The paper reports the efforts made since the mid-1960s in establishing capability for design and manufacture of all equipment and systems required for nuclear power plants. A major constraint in expanding the nuclear power capacity is naturally related to the competing demands on available national resources. The paper also discusses constraints other than purely technological and financial, and describes the efforts being made to overcome them. (author)

India's nuclear power programme and constraints encountered in its implementation

International Nuclear Information System (INIS)

Sethna, H.N.; Srinivasan, M.R.

1977-01-01

Nuclear power development in India is based on the natural uranium fuelled pressurised heavy water reactors. However, in order to acquire early experience in operation and maintenance of nuclear power stations, India's first atomic power station comprised of two units of boiling water reactors. Subsequent nuclear power stations currently in operation or under construction employ natural uranium heavy water reactors and each of the stations is a two reactor installation. While the first two nuclear power stations employ reactors with an output of 235 MW. 500 MW heavy water reactors are visualised for the period beyond 1985. The first nuclear power station was essentially fully imported; the second nuclear power station which employs heavy water reactors already has a significant contribution of equipment manufactured in India. For the third nuclear power station and the subsequent one, practically all equipment is being manufactured indigenously. The nuclear power station at Narora is in a seismic region and hence the design is substantially more advanced than the ones at the earlier sites and also employs concepts which will be used in the 500 MW reactors. Efforts are being made in the country to integrate power generation systems into larger regional grids and eventually into a national grid; however, the distributed nature of power generation at present and other infrastructural limitations still favour small and medium size plants only. The paper brings out the efforts put in over the last ten years in establishing capability for design and manufacture of all equipment and systems required for nuclear power plants. A major constraint in expanding the nuclear power capacity is naturally related to the competing demands on available national resources. The paper also discusses other constraints than purely technological and financial and describes how efforts are being made to overcome these contraints

Autonomously Generating Operations Sequences for a Mars Rover Using Artificial Intelligence-Based Planning

Science.gov (United States)

Sherwood, R.; Mutz, D.; Estlin, T.; Chien, S.; Backes, P.; Norris, J.; Tran, D.; Cooper, B.; Rabideau, G.; Mishkin, A.; Maxwell, S.

2001-07-01

This article discusses a proof-of-concept prototype for ground-based automatic generation of validated rover command sequences from high-level science and engineering activities. This prototype is based on ASPEN, the Automated Scheduling and Planning Environment. This artificial intelligence (AI)-based planning and scheduling system will automatically generate a command sequence that will execute within resource constraints and satisfy flight rules. An automated planning and scheduling system encodes rover design knowledge and uses search and reasoning techniques to automatically generate low-level command sequences while respecting rover operability constraints, science and engineering preferences, environmental predictions, and also adhering to hard temporal constraints. This prototype planning system has been field-tested using the Rocky 7 rover at JPL and will be field-tested on more complex rovers to prove its effectiveness before transferring the technology to flight operations for an upcoming NASA mission. Enabling goal-driven commanding of planetary rovers greatly reduces the requirements for highly skilled rover engineering personnel. This in turn greatly reduces mission operations costs. In addition, goal-driven commanding permits a faster response to changes in rover state (e.g., faults) or science discoveries by removing the time-consuming manual sequence validation process, allowing rapid "what-if" analyses, and thus reducing overall cycle times.

Constrained dynamical systems: separation of constraints into first and second classes

International Nuclear Information System (INIS)

Chitaya, N.P.; Gogilidze, S.A.; Surovtsev, Yu.S.

1996-01-01

In the Dirac approach to the generalized Hamiltonian formalism, dynamical systems with first- and second-class constraints are investigated. The classification and separation of constraints into the first- and second-class ones are presented with the help of passing to an equivalent canonical set of constraints. The general structure of second-class constraints is clarified. 14 refs

Constraints and spandrels of interareal connectomes

Science.gov (United States)

Rubinov, Mikail

2016-12-01

Interareal connectomes are whole-brain wiring diagrams of white-matter pathways. Recent studies have identified modules, hubs, module hierarchies and rich clubs as structural hallmarks of these wiring diagrams. An influential current theory postulates that connectome modules are adequately explained by evolutionary pressures for wiring economy, but that the other hallmarks are not explained by such pressures and are therefore less trivial. Here, we use constraint network models to test these postulates in current gold-standard vertebrate and invertebrate interareal-connectome reconstructions. We show that empirical wiring-cost constraints inadequately explain connectome module organization, and that simultaneous module and hub constraints induce the structural byproducts of hierarchies and rich clubs. These byproducts, known as spandrels in evolutionary biology, include the structural substrate of the default-mode network. Our results imply that currently standard connectome characterizations are based on circular analyses or double dipping, and we emphasize an integrative approach to future connectome analyses for avoiding such pitfalls.

Constraints on grand unified superstring theories

International Nuclear Information System (INIS)

Ellis, J.; Lopez, J.L.; Nanopoulos, D.V.; Houston Advanced Research Center

1990-01-01

We evaluate some constraints on the construction of grand unified superstring theories (GUSTs) using higher level Kac-Moody algebras on the world-sheet. In the most general formulation of the heterotic string in four dimensions, an analysis of the basic GUST model-building constraints, including a realistic hidden gauge group, reveals that there are no E 6 models and any SO(10) models can only exist at level-5. Also, any such SU(5) models can exist only for levels 4≤k≤19. These SO(10) and SU(5) models risk having many large, massless, phenomenologically troublesome representations. We also show that with a suitable hidden sector gauge group, it is possible to avoid free light fractionally charged particles, which are endemic to string derived models. We list all such groups and their representations for the flipped SU(5)xU(1) model. We conclude that a sufficiently binding hidden sector gauge group becomes a basic model-building constraint. (orig.)

Water Constraints in an Electric Sector Capacity Expansion Model

Energy Technology Data Exchange (ETDEWEB)

Macknick, Jordan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cohen, Stuart [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Newmark, Robin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Martinez, Andrew [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sullivan, Patrick [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tidwell, Vince [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-07-17

This analysis provides a description of the first U.S. national electricity capacity expansion model to incorporate water resource availability and costs as a constraint for the future development of the electricity sector. The Regional Energy Deployment System (ReEDS) model was modified to incorporate water resource availability constraints and costs in each of its 134 Balancing Area (BA) regions along with differences in costs and efficiencies of cooling systems. Water resource availability and cost data are from recently completed research at Sandia National Laboratories (Tidwell et al. 2013b). Scenarios analyzed include a business-as-usual 3 This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. scenario without water constraints as well as four scenarios that include water constraints and allow for different cooling systems and types of water resources to be utilized. This analysis provides insight into where water resource constraints could affect the choice, configuration, or location of new electricity technologies.

Formation control of marine craft using constraint functions

DEFF Research Database (Denmark)

Ihle, Ivar-Andre F.; Jouffroy, Jerome; Fossen, Thor I.

This article presents a method for formation control of marine surface vessels inspired by Lagrangian mechanics. The desired formation configuration is given as a set of constraint functions. The functions are treated analytically and by using feedback from the imposed constraint functions, const...

Resources, constraints and capabilities

NARCIS (Netherlands)

Dhondt, S.; Oeij, P.R.A.; Schröder, A.

2018-01-01

Human and financial resources as well as organisational capabilities are needed to overcome the manifold constraints social innovators are facing. To unlock the potential of social innovation for the whole society new (social) innovation friendly environments and new governance structures

String constraints on discrete symmetries in MSSM type II quivers

Energy Technology Data Exchange (ETDEWEB)

Anastasopoulos, Pascal [Technische Univ. Wien (Austria). Inst. fur Theor. Phys.; Cvetic, Mirjam [Univ. of Pennsylvania, Philadelphia PA (United States). Dept. of Physics and Astronomy; Univ. of Maribor (Slovenia). Center for Applied Mathematics and Theoretical Physics; Richter, Robert [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-11-15

We study the presence of discrete gauge symmetries in D-brane semirealistic compactifications. After establishing the constraints on the transformation behaviour of the chiral matter for the presence of a discrete gauge symmetry we perform a systematic search for discrete gauge symmetries within semi-realistic D-brane realizations, based on four D-brane stacks, of the MSSM and the MSSM with three right-handed neutrinos. The systematic search reveals that Proton hexality, a discrete symmetry which ensures the absence of R-parity violating terms as well as the absence of dangerous dimension 5 proton decay operators, is only rarely realized. Moreover, none of the semi-realistic local D-brane configurations exhibit any family dependent discrete gauge symmetry.

An efficient method for minimizing a convex separable logarithmic function subject to a convex inequality constraint or linear equality constraint

Directory of Open Access Journals (Sweden)

2006-01-01

Full Text Available We consider the problem of minimizing a convex separable logarithmic function over a region defined by a convex inequality constraint or linear equality constraint, and two-sided bounds on the variables (box constraints. Such problems are interesting from both theoretical and practical point of view because they arise in some mathematical programming problems as well as in various practical problems such as problems of production planning and scheduling, allocation of resources, decision making, facility location problems, and so forth. Polynomial algorithms are proposed for solving problems of this form and their convergence is proved. Some examples and results of numerical experiments are also presented.

Optimising costs in WLCG operations

CERN Document Server

Pradillo, Mar; Flix, Josep; Forti, Alessandra; Sciabà, Andrea

2015-01-01

The Worldwide LHC Computing Grid project (WLCG) provides the computing and storage resources required by the LHC collaborations to store, process and analyse the 50 Petabytes of data annually generated by the LHC. The WLCG operations are coordinated by a distributed team of managers and experts and performed by people at all participating sites and from all the experiments. Several improvements in the WLCG infrastructure have been implemented during the first long LHC shutdown to prepare for the increasing needs of the experiments during Run2 and beyond. However, constraints in funding will affect not only the computing resources but also the available effort for operations. This paper presents the results of a detailed investigation on the allocation of the effort in the different areas of WLCG operations, identifies the most important sources of inefficiency and proposes viable strategies for optimising the operational cost, taking into account the current trends in the evolution of the computing infrastruc...

Constraints on reusability of learning objects

DEFF Research Database (Denmark)

May, Michael; Hussmann, Peter Munkebo; Jensen, Anne Skov

2010-01-01

It is the aim of this paper to discuss some didactic constraints on the use and reuse of digital modular learning objects. Engineering education is used as the specific context of use with examples from courses in introductory electronics and mathematics. Digital multimedia and modular learning....... Constraints on reuse arise from the nature of conceptual understanding in higher education and the functionality of learning objects within present technologies. We will need didactic as well as technical perspectives on learning objects in designing for understanding....

Core design and operation optimization methods based on time-dependent perturbation theory

International Nuclear Information System (INIS)

Greenspan, E.

1983-08-01

A general approach for the optimization of nuclear reactor core design and operation is outlined; it is based on two cornerstones: a newly developed time-dependent (or burnup-dependent) perturbation theory for nonlinear problems and a succesive iteration technique. The resulting approach is capable of handling realistic reactor models using computational methods of any degree of sophistication desired, while accounting for all the constraints imposed. Three general optimization strategies, different in the way for handling the constraints, are formulated. (author)

Practical constraints on fuel management a utility perspective

International Nuclear Information System (INIS)

Grier, C.A.

1986-01-01

The practical and potential constraints of performing fuel management at a large utility are reviewed. Based on approximately six years of experience in performing fuel management the constraints due to commercial, technical, utility system, design methods, and personnel and computer resources are discussed in detail

Applying the theory of constraints in health care: Part 1--The philosophy.

Science.gov (United States)

Breen, Anne M; Burton-Houle, Tracey; Aron, David C

2002-01-01

The imperative to improve both technical and service quality while simultaneously reducing costs is quite clear. The Theory of Constraints (TOC) is an emerging philosophy that rests on two assumptions: (1) systems thinking and (2) if a constraint "is anything that limits a system from achieving higher performance versus its goal," then every system must have at least one (and at most no more than a few) constraints or limiting factors. A constraint is neither good nor bad in itself. Rather, it just is. In fact, recognition of the existence of constraints represents an excellent opportunity for improvement because it allows one to focus ones efforts in the most productive area--identifying and managing the constraints. This is accomplished by using the five focusing steps of TOC: (1) identify the system's constraint; (2) decide how to exploit it; (3) subordinate/synchronize everything else to the above decisions; (4) elevate the system's constraint; and (5) if the constraint has shifted in the above steps, go back to step 1. Do not allow inertia to become the system's constraint. TOC also refers to a series of tools termed "thinking processes" and the sequence in which they are used.

A methodology for controlling motion and constraint forces in holonomically constrained systems

International Nuclear Information System (INIS)

Sapio, Vincent De; Srinivasa, Narayan

2015-01-01

Holonomic constraints are ubiquitous in multibody systems. We present an approach to effectively address the control of holonomically constrained systems using a novel decomposition of task, constraint, and posture space. In addition to providing a natural approach for motion control in the presence of constraints, this scheme also allows for concurrent specification of desired constraint forces, given sufficient actuation. It does this by exposing both motion coordinates and constraint forces within the control formalism, allowing for substantial flexibility in control synthesis. Implementations are presented based on a partitioning of the constraint forces into controlled and uncontrolled subsets, as well as a specification of implicit conditions on the constraint forces. A number of examples demonstrate the practical efficacy of the approach. Finally, a system-level methodology for constraint management during robot interactions with the environment is presented

A methodology for controlling motion and constraint forces in holonomically constrained systems

Energy Technology Data Exchange (ETDEWEB)

Sapio, Vincent De, E-mail: vdesapio@hrl.com; Srinivasa, Narayan, E-mail: nsrinivasa@hrl.com [HRL Laboratories, LLC, Information and Systems Sciences Laboratory (United States)

2015-02-15

Holonomic constraints are ubiquitous in multibody systems. We present an approach to effectively address the control of holonomically constrained systems using a novel decomposition of task, constraint, and posture space. In addition to providing a natural approach for motion control in the presence of constraints, this scheme also allows for concurrent specification of desired constraint forces, given sufficient actuation. It does this by exposing both motion coordinates and constraint forces within the control formalism, allowing for substantial flexibility in control synthesis. Implementations are presented based on a partitioning of the constraint forces into controlled and uncontrolled subsets, as well as a specification of implicit conditions on the constraint forces. A number of examples demonstrate the practical efficacy of the approach. Finally, a system-level methodology for constraint management during robot interactions with the environment is presented.

Constraints on the ωπ Form Factor from Analyticity and Unitarity

Science.gov (United States)

Ananthanarayan, B.; Caprini, Irinel; Kubis, Bastian

Form factors are important low-energy quantities and an accurate knowledge of these sheds light on the strong interactions. A variety of methods based on general principles have been developed to use information known in different energy regimes to constrain them in regions where experimental information needs to be tested precisely. Here we review our recent work on the electromagnetic ωπ form factor in a model-independent framework known as the method of unitarity bounds, partly motivated by the discre-pancies noted recently between the theoretical calculations of the form factor based on dispersion relations and certain experimental data measured from the decay ω → π0γ*. We have applied a modified dispersive formalism, which uses as input the discontinuity of the ωπ form factor calculated by unitarity below the ωπ threshold and an integral constraint on the square of its modulus above this threshold. The latter constraint was obtained by exploiting unitarity and the positivity of the spectral function of a QCD correlator, computed on the spacelike axis by operator product expansion and perturbative QCD. An alternative constraint is obtained by using data available at higher energies for evaluating an integral of the modulus squared with a suitable weight function. From these conditions we derived upper and lower bounds on the modulus of the ωπ form factor in the region below the ωπ threshold. The results confirm the existence of a disagreement between dispersion theory and experimental data on the ωπ form factor around 0:6 GeV, including those from NA60 published in 2016.

Satellite end of life constraints: Technical and organisational solutions

Science.gov (United States)

Cabrières, Bernard; Alby, Fernand; Cazaux, Christian

2012-04-01

Since 1974 with the radiocommunication satellite Symphony1, CNES launched and operated 11 GEO and 20 LEO satellites. During those 36 years, both flight segment and ground segment dramatically evolved and operational organisations and techniques equally improved. At the present time, CNES operates 1 GEO satellite and 17 LEO satellites with not much more people and costs than in 1986 when its first Satellite Operation Direction in Toulouse was only in charge of Telecom1A, Telecom1B and Spot1. This fantastic technical evolution combined with the huge increase of services to citizens and governments given by Space systems was unfortunately also associated with an enormous growth of space pollution by debris of all sizes. From the beginning, CNES was a major actor of the international effort to promote regulations in order to try to reduce or at least control this problematic situation. Internally, CNES, not only set up an operational on-call service to deal with collision risks, but decided to do its best to apply the new guidelines to the end of life of satellites under its responsibility even for those developed and launched a very long time ago. For instance, that was the case in 2009 for the reorbitation of the GEO satellite Telecom 2C (launched in 1995) and for the deorbitation of the LEO satellite Spot2 (launched in 1990). In addition, CNES prepares procedures to be able to be as exemplary as possible for its other spacecrafts whose end of life approaches. The constraints and challenges to face in order to cope with these new requirements are multiple: choice of final orbit, realistic calculation of re-entry duration, estimation of residual propellant, electric passivation, management of explosion risks… All these studies and operational experience gained will be helpful for the new role of CNES, which recently became in charge of controlling space operators in the frame of the new French space law on space operations.

Consistency maintenance for constraint in role-based access control model

Institute of Scientific and Technical Information of China (English)

韩伟力; 陈刚; 尹建伟; 董金祥

2002-01-01

Constraint is an important aspect of role-based access control and is sometimes argued to be the principal motivation for role-based access control (RBAC). But so far few authors have discussed consistency maintenance for constraint in RBAC model. Based on researches of constraints among roles and types of inconsistency among constraints, this paper introduces corresponding formal rules, rule-based reasoning and corresponding methods to detect, avoid and resolve these inconsistencies. Finally, the paper introduces briefly the application of consistency maintenance in ZD-PDM, an enterprise-oriented product data management (PDM) system.

Consistency maintenance for constraint in role-based access control model

Institute of Scientific and Technical Information of China (English)

韩伟力; 陈刚; 尹建伟; 董金祥

2002-01-01

Constraint is an important aspect of role-based access control and is sometimes argued to be the principal motivation for role-based access control (RBAC). But so far'few authors have discussed consistency maintenance for constraint in RBAC model. Based on researches of constraints among roles and types of inconsistency among constraints, this paper introduces correaponding formal rules, rulebased reasoning and corresponding methods to detect, avoid and resolve these inconsistencies. Finally,the paper introduces briefly the application of consistency maintenance in ZD-PDM, an enterprise-ori-ented product data management (PDM) system.

Power control method for load-frequency control operation in BWRs

International Nuclear Information System (INIS)

Ie, Shin-ichiroo; Ohgo, Yu-kiharu; Itou, Tetsuo; Shida, Tooichi

1991-01-01

The preliminary design of an advanced power control method for fast load-following [load frequency control (LFC)] maneuvers in a boiling water reactor (BWR) is described in this paper. Application of a multivariable control method using an optimal linear quadratic (LQ) regulator theory effectively improves control system performance when system variables have significant interactions such as in BWRs. The control problem, however, demands strict constraints on system variable from the standpoint of plant operation. These constraints require the control system to have a nonlinear property for better improvement. Therefore, the effectiveness of LQ control is limited by these constraints, because it is based on a linear model. A new method is needed to compensate for the nonlinear property. In this study, the authors propose a new method using fuzzy reasoning with LQ control to achieve nonlinear compensation

Quantum centipedes with strong global constraint

Science.gov (United States)

Grange, Pascal

2017-06-01

A centipede made of N quantum walkers on a one-dimensional lattice is considered. The distance between two consecutive legs is either one or two lattice spacings, and a global constraint is imposed: the maximal distance between the first and last leg is N  +  1. This is the strongest global constraint compatible with walking. For an initial value of the wave function corresponding to a localized configuration at the origin, the probability law of the first leg of the centipede can be expressed in closed form in terms of Bessel functions. The dispersion relation and the group velocities are worked out exactly. Their maximal group velocity goes to zero when N goes to infinity, which is in contrast with the behaviour of group velocities of quantum centipedes without global constraint, which were recently shown by Krapivsky, Luck and Mallick to give rise to ballistic spreading of extremal wave-front at non-zero velocity in the large-N limit. The corresponding Hamiltonians are implemented numerically, based on a block structure of the space of configurations corresponding to compositions of the integer N. The growth of the maximal group velocity when the strong constraint is gradually relaxed is explored, and observed to be linear in the density of gaps allowed in the configurations. Heuristic arguments are presented to infer that the large-N limit of the globally constrained model can yield finite group velocities provided the allowed number of gaps is a finite fraction of N.

Operators' Accessibility Studies using Virtual Reality

OpenAIRE

Louison , Céphise ,; Ferlay , Fabien ,; Keller , Delphine ,; Mestre , Daniel ,

2016-01-01

International audience; The development of fusion plants is more and more challenging. Compared to previous fusion experimental devices, integration constraints, maintenance and safety requirements are key parameters in the ITER project. Components are designed in parallel and we must consider integration, assembly and maintenance issues, which might have a huge impact on the overall design. That also implies to consider the operator's feedback to assess the feasibility of accessibility or ma...

Parallel handling of integrity constraints on fragmented relations

NARCIS (Netherlands)

Grefen, P.W.P.J.; Apers, Peter M.G.

A short introduction to the important aspects of the PRISMA DBMS (database management system) and to the notation and terminology used is presented. It is shown how integrity constraints formulated in terms of global relations can be translated into a fragmented form. The strategy for constraint

A Constraint Model for Constrained Hidden Markov Models

DEFF Research Database (Denmark)

Christiansen, Henning; Have, Christian Theil; Lassen, Ole Torp

2009-01-01

A Hidden Markov Model (HMM) is a common statistical model which is widely used for analysis of biological sequence data and other sequential phenomena. In the present paper we extend HMMs with constraints and show how the familiar Viterbi algorithm can be generalized, based on constraint solving ...

ANALYSIS OF CONSTRAINTS IN RESOURCE USE EFFICIENCY IN ...

African Journals Online (AJOL)

ANALYSIS OF CONSTRAINTS IN RESOURCE USE EFFICIENCY IN MULTIPLE CROPPING SYSTEM BY SMALL-HOLDER FARMERS IN EBONYI STATE OF ... high cost of modern inputs, lack of adequate finance and lack of collaterals among others served as major constraints, which constituted29%, 36%, 33% and 22% ...

Spin glasses and nonlinear constraints in portfolio optimization

International Nuclear Information System (INIS)

Andrecut, M.

2014-01-01

We discuss the portfolio optimization problem with the obligatory deposits constraint. Recently it has been shown that as a consequence of this nonlinear constraint, the solution consists of an exponentially large number of optimal portfolios, completely different from each other, and extremely sensitive to any changes in the input parameters of the problem, making the concept of rational decision making questionable. Here we reformulate the problem using a quadratic obligatory deposits constraint, and we show that from the physics point of view, finding an optimal portfolio amounts to calculating the mean-field magnetizations of a random Ising model with the constraint of a constant magnetization norm. We show that the model reduces to an eigenproblem, with 2N solutions, where N is the number of assets defining the portfolio. Also, in order to illustrate our results, we present a detailed numerical example of a portfolio of several risky common stocks traded on the Nasdaq Market.

Spin glasses and nonlinear constraints in portfolio optimization

Energy Technology Data Exchange (ETDEWEB)

Andrecut, M., E-mail: mircea.andrecut@gmail.com

2014-01-17

We discuss the portfolio optimization problem with the obligatory deposits constraint. Recently it has been shown that as a consequence of this nonlinear constraint, the solution consists of an exponentially large number of optimal portfolios, completely different from each other, and extremely sensitive to any changes in the input parameters of the problem, making the concept of rational decision making questionable. Here we reformulate the problem using a quadratic obligatory deposits constraint, and we show that from the physics point of view, finding an optimal portfolio amounts to calculating the mean-field magnetizations of a random Ising model with the constraint of a constant magnetization norm. We show that the model reduces to an eigenproblem, with 2N solutions, where N is the number of assets defining the portfolio. Also, in order to illustrate our results, we present a detailed numerical example of a portfolio of several risky common stocks traded on the Nasdaq Market.

Model quality assessment using distance constraints from alignments

DEFF Research Database (Denmark)

Paluszewski, Martin; Karplus, Kevin

2008-01-01

that model which is closest to the true structure. In this article, we present a new approach for addressing the MQA problem. It is based on distance constraints extracted from alignments to templates of known structure, and is implemented in the Undertaker program for protein structure prediction. One novel...... feature is that we extract noncontact constraints as well as contact constraints. We describe how the distance constraint extraction is done and we show how they can be used to address the MQA problem. We have compared our method on CASP7 targets and the results show that our method is at least comparable...... with the best MQA methods that were assessed at CASP7. We also propose a new evaluation measure, Kendall's tau, that is more interpretable than conventional measures used for evaluating MQA methods (Pearson's r and Spearman's rho). We show clear examples where Kendall's tau agrees much more with our intuition...

Managing Constraint Generators in Retail Design Processes

DEFF Research Database (Denmark)

Münster, Mia Borch; Haug, Anders

case studies of fashion store design projects, the present paper addresses this gap. The and six case studies of fashion store design projects, the present paper sheds light on the types of constraints generated by the relevant constraint generators. The paper shows that in the cases studied......Retail design concepts are complex designs meeting functional and aesthetic demands. During a design process a retail designer has to consider various constraint generators such as stakeholder interests, physical limitations and restrictions. Obviously the architectural site, legislators...... and landlords need to be considered as well as the interest of the client and brand owner. Furthermore the users need to be taken into account in order to develop an interesting and functional shopping and working environments. Finally, suppliers and competitors may influence the design with regard...

Geostatistical regularization operators for geophysical inverse problems on irregular meshes

Science.gov (United States)

Jordi, C.; Doetsch, J.; Günther, T.; Schmelzbach, C.; Robertsson, J. OA

2018-05-01

Irregular meshes allow to include complicated subsurface structures into geophysical modelling and inverse problems. The non-uniqueness of these inverse problems requires appropriate regularization that can incorporate a priori information. However, defining regularization operators for irregular discretizations is not trivial. Different schemes for calculating smoothness operators on irregular meshes have been proposed. In contrast to classical regularization constraints that are only defined using the nearest neighbours of a cell, geostatistical operators include a larger neighbourhood around a particular cell. A correlation model defines the extent of the neighbourhood and allows to incorporate information about geological structures. We propose an approach to calculate geostatistical operators for inverse problems on irregular meshes by eigendecomposition of a covariance matrix that contains the a priori geological information. Using our approach, the calculation of the operator matrix becomes tractable for 3-D inverse problems on irregular meshes. We tested the performance of the geostatistical regularization operators and compared them against the results of anisotropic smoothing in inversions of 2-D surface synthetic electrical resistivity tomography (ERT) data as well as in the inversion of a realistic 3-D cross-well synthetic ERT scenario. The inversions of 2-D ERT and seismic traveltime field data with geostatistical regularization provide results that are in good accordance with the expected geology and thus facilitate their interpretation. In particular, for layered structures the geostatistical regularization provides geologically more plausible results compared to the anisotropic smoothness constraints.

Importance of the local constraint in slave-boson theories

International Nuclear Information System (INIS)

Zhang, L.; Jain, J.K.; Emery, V.J.

1993-01-01

Slave bosons are commonly introduced in order to implement an infinite Hubbard U by means of a local constraint. The usual starting point for investigations within this scheme is a mean-field theory in which the constraint is taken to be global. This approximate treatment of the constraint is studied in the context of a two-band Hubbard model, and it is shown that (i) the ground state has a significant number of doubly occupied sites, despite the infinite on-site repulsion in the original model, and (ii) there is an unphysical tendency for pairing. However, it is found that if the local constraint is retained for the insulator at half filling, then mean-field theory gives the correct result that the double occupancy is zero

Exact penalty results for mathematical programs with vanishing constraints

Czech Academy of Sciences Publication Activity Database

Hoheisel, T.; Kanzow, Ch.; Outrata, Jiří

2010-01-01

Roč. 72, č. 5 (2010), s. 2514-2526 ISSN 0362-546X R&D Projects: GA AV ČR IAA100750802 Institutional research plan: CEZ:AV0Z10750506 Keywords : Mathematical programs with vanishing constraints * Mathematical programs with equilibrium constraints * Exact penalization * Calmness * Subdifferential calculus * Limiting normal cone Subject RIV: BA - General Mathematics Impact factor: 1.279, year: 2010 http://library.utia.cas.cz/separaty/2010/MTR/outrata-exact penalty results for mathematical programs with vanishing constraints.pdf

Social Constraints on Animate Vision

National Research Council Canada - National Science Library

Breazeal, Cynthia; Edsinger, Aaron; Fitzpatrick, Paul; Scassellati, Brian

2000-01-01

.... In humanoid robotic systems, or in any animate vision system that interacts with people, social dynamics provide additional levels of constraint and provide additional opportunities for processing economy...

Ecosystems emerging. 5: Constraints

Czech Academy of Sciences Publication Activity Database

Patten, B. C.; Straškraba, Milan; Jorgensen, S. E.

2011-01-01

Roč. 222, č. 16 (2011), s. 2945-2972 ISSN 0304-3800 Institutional research plan: CEZ:AV0Z50070508 Keywords : constraint * epistemic * ontic Subject RIV: EH - Ecology, Behaviour Impact factor: 2.326, year: 2011 http://www.sciencedirect.com/science/article/pii/S0304380011002274

HOROPLAN: computer-assisted nurse scheduling using constraint-based programming.

Science.gov (United States)

Darmoni, S J; Fajner, A; Mahé, N; Leforestier, A; Vondracek, M; Stelian, O; Baldenweck, M

1995-01-01

Nurse scheduling is a difficult and time consuming task. The schedule has to determine the day to day shift assignments of each nurse for a specified period of time in a way that satisfies the given requirements as much as possible, taking into account the wishes of nurses as closely as possible. This paper presents a constraint-based, artificial intelligence approach by describing a prototype implementation developed with the Charme language and the first results of its use in the Rouen University Hospital. Horoplan implements a non-cyclical constraint-based scheduling, using some heuristics. Four levels of constraints were defined to give a maximum of flexibility: French level (e.g. number of worked hours in a year), hospital level (e.g. specific day-off), department level (e.g. specific shift) and care unit level (e.g. specific pattern for week-ends). Some constraints must always be verified and can not be overruled and some constraints can be overruled at a certain cost. Rescheduling is possible at any time specially in case of an unscheduled absence.

Nonnegative Matrix Factorization with Rank Regularization and Hard Constraint.

Science.gov (United States)

Shang, Ronghua; Liu, Chiyang; Meng, Yang; Jiao, Licheng; Stolkin, Rustam

2017-09-01

Nonnegative matrix factorization (NMF) is well known to be an effective tool for dimensionality reduction in problems involving big data. For this reason, it frequently appears in many areas of scientific and engineering literature. This letter proposes a novel semisupervised NMF algorithm for overcoming a variety of problems associated with NMF algorithms, including poor use of prior information, negative impact on manifold structure of the sparse constraint, and inaccurate graph construction. Our proposed algorithm, nonnegative matrix factorization with rank regularization and hard constraint (NMFRC), incorporates label information into data representation as a hard constraint, which makes full use of prior information. NMFRC also measures pairwise similarity according to geodesic distance rather than Euclidean distance. This results in more accurate measurement of pairwise relationships, resulting in more effective manifold information. Furthermore, NMFRC adopts rank constraint instead of norm constraints for regularization to balance the sparseness and smoothness of data. In this way, the new data representation is more representative and has better interpretability. Experiments on real data sets suggest that NMFRC outperforms four other state-of-the-art algorithms in terms of clustering accuracy.

Cyclic labellings with constraints at two distances

OpenAIRE

Leese, R; Noble, S D

2004-01-01

Motivated by problems in radio channel assignment, we consider the vertex-labelling of graphs with non-negative integers. The objective is to minimise the span of the labelling, subject to constraints imposed at graph distances one and two. We show that the minimum span is (up to rounding) a piecewise linear function of the constraints, and give a complete specification, together with associated optimal assignments, for trees and cycles.

Adjustment and Optimization of the Cropping Systems under Water Constraint

Directory of Open Access Journals (Sweden)

Pingli An

2016-11-01

Full Text Available The water constraint on agricultural production receives growing concern with the increasingly sharp contradiction between demand and supply of water resources. How to mitigate and adapt to potential water constraint is one of the key issues for ensuring food security and achieving sustainable agriculture in the context of climate change. It has been suggested that adjustment and optimization of cropping systems could be an effective measure to improve water management and ensure food security. However, a knowledge gap still exists in how to quantify potential water constraint and how to select appropriate cropping systems. Here, we proposed a concept of water constraint risk and developed an approach for the evaluation of the water constraint risks for agricultural production by performing a case study in Daxing District, Beijing, China. The results show that, over the whole growth period, the order of the water constraint risks of crops from high to low was wheat, rice, broomcorn, foxtail millet, summer soybean, summer peanut, spring corn, and summer corn, and the order of the water constraint risks of the cropping systems from high to low was winter wheat-summer grain crops, rice, broomcorn, foxtail millet, and spring corn. Our results are consistent with the actual evolving process of cropping system. This indicates that our proposed method is practicable to adjust and optimize the cropping systems to mitigate and adapt to potential water risks. This study provides an insight into the adjustment and optimization of cropping systems under resource constraints.

A scientific operations plan for the large space telescope. [ground support system design

Science.gov (United States)

West, D. K.

1977-01-01

The paper describes an LST ground system which is compatible with the operational requirements of the LST. The goal of the approach is to minimize the cost of post launch operations without seriously compromising the quality and total throughput of LST science. Attention is given to cost constraints and guidelines, the telemetry operations processing systems (TELOPS), the image processing facility, ground system planning and data flow, and scientific interfaces.

Production constraints and perceived marketing problems of stock ...

African Journals Online (AJOL)

In an endeavour to improve the livestock production and particularly the marketing of livestock in the Northern Communal Areas of Namibia, this study analyses the perception of livestock farmers in this regard. The low off-take percentage is the most serious production constraint, but marketing, although a constraint, is not ...

Cluster-cluster correlations and constraints on the correlation hierarchy

Science.gov (United States)

Hamilton, A. J. S.; Gott, J. R., III

1988-01-01

The hypothesis that galaxies cluster around clusters at least as strongly as they cluster around galaxies imposes constraints on the hierarchy of correlation amplitudes in hierachical clustering models. The distributions which saturate these constraints are the Rayleigh-Levy random walk fractals proposed by Mandelbrot; for these fractal distributions cluster-cluster correlations are all identically equal to galaxy-galaxy correlations. If correlation amplitudes exceed the constraints, as is observed, then cluster-cluster correlations must exceed galaxy-galaxy correlations, as is observed.

Algorithms and ordering heuristics for distributed constraint satisfaction problems

CERN Document Server

Wahbi , Mohamed

2013-01-01

DisCSP (Distributed Constraint Satisfaction Problem) is a general framework for solving distributed problems arising in Distributed Artificial Intelligence.A wide variety of problems in artificial intelligence are solved using the constraint satisfaction problem paradigm. However, there are several applications in multi-agent coordination that are of a distributed nature. In this type of application, the knowledge about the problem, that is, variables and constraints, may be logically or geographically distributed among physical distributed agents. This distribution is mainly due to p

Entropy of Bit-Stuffing-Induced Measures for Two-Dimensional Checkerboard Constraints

DEFF Research Database (Denmark)

Forchhammer, Søren; Vaarby, Torben Strange

2007-01-01

A modified bit-stuffing scheme for two-dimensional (2-D) checkerboard constraints is introduced. The entropy of the scheme is determined based on a probability measure defined by the modified bit-stuffing. Entropy results of the scheme are given for 2-D constraints on a binary alphabet....... The constraints considered are 2-D RLL (d, infinity) for d = 2, 3 and 4 as well as for the constraint with a minimum 1-norm distance of 3 between Is. For these results the entropy is within 1-2% of an upper bound on the capacity for the constraint. As a variation of the scheme, periodic merging arrays are also...

Producing Satisfactory Solutions to Scheduling Problems: An Iterative Constraint Relaxation Approach

Science.gov (United States)

Chien, S.; Gratch, J.

1994-01-01

One drawback to using constraint-propagation in planning and scheduling systems is that when a problem has an unsatisfiable set of constraints such algorithms typically only show that no solution exists. While, technically correct, in practical situations, it is desirable in these cases to produce a satisficing solution that satisfies the most important constraints (typically defined in terms of maximizing a utility function). This paper describes an iterative constraint relaxation approach in which the scheduler uses heuristics to progressively relax problem constraints until the problem becomes satisfiable. We present empirical results of applying these techniques to the problem of scheduling spacecraft communications for JPL/NASA antenna resources.

Tailored parameter optimization methods for ordinary differential equation models with steady-state constraints.

Science.gov (United States)

Fiedler, Anna; Raeth, Sebastian; Theis, Fabian J; Hausser, Angelika; Hasenauer, Jan

2016-08-22

Ordinary differential equation (ODE) models are widely used to describe (bio-)chemical and biological processes. To enhance the predictive power of these models, their unknown parameters are estimated from experimental data. These experimental data are mostly collected in perturbation experiments, in which the processes are pushed out of steady state by applying a stimulus. The information that the initial condition is a steady state of the unperturbed process provides valuable information, as it restricts the dynamics of the process and thereby the parameters. However, implementing steady-state constraints in the optimization often results in convergence problems. In this manuscript, we propose two new methods for solving optimization problems with steady-state constraints. The first method exploits ideas from optimization algorithms on manifolds and introduces a retraction operator, essentially reducing the dimension of the optimization problem. The second method is based on the continuous analogue of the optimization problem. This continuous analogue is an ODE whose equilibrium points are the optima of the constrained optimization problem. This equivalence enables the use of adaptive numerical methods for solving optimization problems with steady-state constraints. Both methods are tailored to the problem structure and exploit the local geometry of the steady-state manifold and its stability properties. A parameterization of the steady-state manifold is not required. The efficiency and reliability of the proposed methods is evaluated using one toy example and two applications. The first application example uses published data while the second uses a novel dataset for Raf/MEK/ERK signaling. The proposed methods demonstrated better convergence properties than state-of-the-art methods employed in systems and computational biology. Furthermore, the average computation time per converged start is significantly lower. In addition to the theoretical results, the

Telescience testbed: Operational support functions for biomedical experiments

Science.gov (United States)