SN 2008ha: An Extremely Low Luminosity and Extremely Low Energy Supernova
Foley, Ryan J.; Chornock, Ryan; Filippenko, Alexei V.; Ganeshalingam, Mohan; Kirshner, Robert P.; Li, Weidong; Cenko, S. Bradley; Challis, Pete; Friedman, Andrew S.; Modjaz, Maryam; Silverman, Jeffrey M.; Wood-Vasey, W. Michael
2009-01-01
We present ultraviolet, optical, and near-infrared photometry as well as optical spectra of the peculiar supernova (SN) 2008ha. SN 2008ha had a very low peak luminosity, reaching only M_V = -14.2 mag, and low line velocities of only ~2000 km/s near maximum brightness, indicating a very small kinetic energy per unit mass of ejecta. Spectroscopically, SN 2008ha is a member of the SN 2002cx-like class of SNe, a peculiar subclass of SNe Ia; however, SN 2008ha is the most extreme member, being sig...
Design for Additive Manufacturing: Trends, opportunities, considerations, and constraints
Thompson, Mary Kathryn; Moroni, Giovanni; Vaneker, Tom;
2016-01-01
The past few decades have seen substantial growth in Additive Manufacturing (AM) technologies. However, this growth has mainly been process-driven. The evolution of engineering design to take advantage of the possibilities afforded by AM and to manage the constraints associated with the technology...... has lagged behind. This paper presents the major opportunities, constraints, and economic considerations for Design for Additive Manufacturing. It explores issues related to design and redesign for direct and indirect AM production. It also highlights key industrial applications, outlines future...
1-Skeletons of the Spanning Tree Problems with Additional Constraints
V. A. Bondarenko
2015-10-01
Full Text Available In this paper, we study polyhedral properties of two spanning tree problems with additional constraints. In the first problem, it is required to find a tree with a minimum sum of edge weights among all spanning trees with the number of leaves less than or equal to a given value. In the second problem, an additional constraint is the assumption that the degree of all nodes of the spanning tree does not exceed a given value. The recognition versions of both problems are NP-complete. We consider polytopes of these problems and their 1-skeletons. We prove that in both cases it is a NP-complete problem to determine whether the vertices of 1-skeleton are adjacent. Although it is possible to obtain a superpolynomial lower bounds on the clique numbers of these graphs. These values characterize the time complexity in a broad class of algorithms based on linear comparisons. The results indicate a fundamental difference between combinatorial and geometric properties of the considered problems from the classical minimum spanning tree problem.
Deflagrations in hybrid CONe white dwarfs: a route to explain the faint Type Iax supernova 2008ha
Kromer, M; Pakmor, R; Ruiter, A J; Hillebrandt, W; Marquardt, K S; Roepke, F K; Seitenzahl, I R; Sim, S A; Taubenberger, S
2015-01-01
Stellar evolution models predict the existence of hybrid white dwarfs (WDs) with a carbon-oxygen core surrounded by an oxygen-neon mantle. Being born with masses ~1.1 Msun, hybrid WDs in a binary system may easily approach the Chandrasekhar mass (MCh) by accretion and give rise to a thermonuclear explosion. Here, we investigate an off-centre deflagration in a near-MCh hybrid WD under the assumption that nuclear burning only occurs in carbon-rich material. Performing hydrodynamics simulations of the explosion and detailed nucleosynthesis post-processing calculations, we find that only 0.014 Msun of material is ejected while the remainder of the mass stays bound. The ejecta consist predominantly of iron-group elements, O, C, Si and S. We also calculate synthetic observables for our model and find reasonable agreement with the faint Type Iax SN 2008ha. This shows for the first time that deflagrations in near-MCh WDs can in principle explain the observed diversity of Type Iax supernovae. Leaving behind a near-MCh...
Can an energy balance model provide additional constraints on how to close the energy imbalance?
Wohlfahrt, Georg; Widmoser, Peter
2013-01-01
Elucidating the causes for the energy imbalance, i.e. the phenomenon that eddy covariance latent and sensible heat fluxes fall short of available energy, is an outstanding problem in micrometeorology. This paper tests the hypothesis that the full energy balance, through incorporation of additional independent measurements which determine the driving forces of and resistances to energy transfer, provides further insights into the causes of the energy imbalance and additional constraints on ene...
Constraints on an additional Z' gauge boson versus the W, the top and the Higgs masses
We analyse the restrictions on the mass and the mixing of an additional Z' gauge boson that follow from the recent LEP measurements taking into account standard model (SM) radiative corrections. We find that these restrictions depend sharply on the assumed values for the SM structural parameters, the most important of which are MW and mtop. The constraints become stronger for lighter W and heavier top. (orig.)
Krivova, N. A.; Ilin, V. B.; Fischer, O.
1996-01-01
For the Herbig Ae stars with Algol-like minima (UX Ori, WW Vul, etc), the effects of circumstellar dust include: excess infrared emission, anomalous ultraviolet extinction, the 'blueing' of the stars in minima accompanying by an increase of intrinsic polarization. Using a Monte-Carlo code for polarized radiation transfer we have simulated these effects and compared the results obtained for different models with the observational data available. We found that the photometric and polarimetric behavior of the stars provided essential additional constraints on the circumstellar dust models. The models with spheroidal shell geometry and compact (non-fluffy) dust grains do not appear to be able to explain all the data.
Can an energy balance model provide additional constraints on how to close the energy imbalance?
Wohlfahrt, Georg; Widmoser, Peter
2013-02-15
Elucidating the causes for the energy imbalance, i.e. the phenomenon that eddy covariance latent and sensible heat fluxes fall short of available energy, is an outstanding problem in micrometeorology. This paper tests the hypothesis that the full energy balance, through incorporation of additional independent measurements which determine the driving forces of and resistances to energy transfer, provides further insights into the causes of the energy imbalance and additional constraints on energy balance closure options. Eddy covariance and auxiliary data from three different biomes were used to test five contrasting closure scenarios. The main result of our study is that except for nighttime, when fluxes were low and noisy, the full energy balance generally did not contain enough information to allow further insights into the causes of the imbalance and to constrain energy balance closure options. Up to four out of the five tested closure scenarios performed similarly and in up to 53% of all cases all of the tested closure scenarios resulted in plausible energy balance values. Our approach may though provide a sensible consistency check for eddy covariance energy flux measurements. PMID:24465072
Doligez, B.; Eschard, R. [Institut Francais du Petrole, Rueil Malmaison (France); Geffroy, F. [Centre de Geostatistique, Fontainebleau (France)] [and others
1997-08-01
The classical approach to construct reservoir models is to start with a fine scale geological model which is informed with petrophysical properties. Then scaling-up techniques allow to obtain a reservoir model which is compatible with the fluid flow simulators. Geostatistical modelling techniques are widely used to build the geological models before scaling-up. These methods provide equiprobable images of the area under investigation, which honor the well data, and which variability is the same than the variability computed from the data. At an appraisal phase, when few data are available, or when the wells are insufficient to describe all the heterogeneities and the behavior of the field, additional constraints are needed to obtain a more realistic geological model. For example, seismic data or stratigraphic models can provide average reservoir information with an excellent areal coverage, but with a poor vertical resolution. New advances in modelisation techniques allow now to integrate this type of additional external information in order to constrain the simulations. In particular, 2D or 3D seismic derived information grids, or sand-shale ratios maps coming from stratigraphic models can be used as external drifts to compute the geological image of the reservoir at the fine scale. Examples are presented to illustrate the use of these new tools, their impact on the final reservoir model, and their sensitivity to some key parameters.
Constraints on additional Z' gauge bosons from a precise measurement of the Z mass
González García, Mª Concepción; Furtado Valle, José Wagner
1990-01-01
We analyze the constraints on the mass and mixing of a superstring-inspired E6 Z' neutral gauge boson that follow from the recent precise Z mass measurements and show that they depend very sensitively on the assumed value of the W mass and also, to a lesser extent, on the top-quark mass.
May, Stephen
2011-01-01
For over 15 years now, various commentators have highlighted the 'monolingual bias' inherent in SLA and TESOL research, which invariably constructs bi/multilingualism in deficit terms. In contrast, these critics have advocated an additive bilingual approach to SLA and TESOL, albeit, not as yet to any great effect. In this paper, I explore why so…
Shin, I -G; Choi, J -Y; Hwang, K -H; Jung, Y K; Park, H
2015-01-01
High-magnification gravitational microlensing events provide an important channel of detecting planetary systems with multiple giants located at their birth places. In order to investigate the potential existence of additional planets, we reanalyze the light curves of the eight high-magnification microlensing events for each of which a single planet was previously detected. The analyzed events include OGLE-2005-BLG-071, OGLE-2005-BLG-169, MOA-2007-BLG-400, MOA-2008-BLG-310, MOA-2009-BLG-319, MOA-2009-BLG-387, MOA-2010-BLG-477, and MOA-2011-BLG-293. We find that including an additional planet improves fits with $\\Delta\\chi^2 < 80$ for seven out of eight analyzed events. For MOA-2009-BLG-319, the improvement is relatively big with $\\Delta\\chi^2 \\sim 143$. From inspection of the fits, we find that the improvement of the fits is attributed to systematics in data. Although no clear evidence of additional planets is found, it is still possible to constrain the existence of additional planets in the parameter spa...
Pulse electrodeposition was to produce nanocrystalline (nc) zinc from alkaline non-cyanide electrolyte with primary and secondary additives. The combined effect of pulse parameters (ON-time (TON), OFF-time (TOFF), pulse peak current density (IP)) and additives on the corrosion properties (evaluated using electrochemical techniques) of zinc electrodeposits are elucidated in terms of surface morphology (using scanning electron microscope), topography and root mean square (RMS) roughness (using atomic force microscope), crystallite size, its orientations and relative texture co-efficient (RTC, %) were evaluated using X-ray diffraction. The corrosion resistance of zinc electrodeposits obtained at constant TON and IP enhanced (i.e., low Icorr and high Rct values) with increased TOFF. At constant TOFF and IP, the Icorr values increased and Rct values decreased with TON while the former decreases and latter increases with IP at constant TON and TOFF. The inclusion of primary and secondary additives into the electrolyte produced nc zinc electrodeposits at 5 Adm-2, showed enhanced protective properties (Icorr-16 μA cm-2 and Rct-481.8 Ω cm-2). Fine grained due to high negative overpotential, reduced roughness and higher percentage of basal plane [0 0. 2] orientation have major impact for the enhanced corrosion resistances.
Chandrasekar, M.S. [Indian Institute of Technology-Madras, Chennai 36 (India); Shanmugasigamani [Central Electrochemical Research Institute, Karaikudi 6 (India); Malathy, Pushpavanam, E-mail: malathypush@yahoo.com [Alagappa Chettiar College of Engineering and Technology, Karaikudi 6 (India)
2010-11-01
Pulse electrodeposition was to produce nanocrystalline (nc) zinc from alkaline non-cyanide electrolyte with primary and secondary additives. The combined effect of pulse parameters (ON-time (T{sub ON}), OFF-time (T{sub OFF}), pulse peak current density (I{sub P})) and additives on the corrosion properties (evaluated using electrochemical techniques) of zinc electrodeposits are elucidated in terms of surface morphology (using scanning electron microscope), topography and root mean square (RMS) roughness (using atomic force microscope), crystallite size, its orientations and relative texture co-efficient (RTC, %) were evaluated using X-ray diffraction. The corrosion resistance of zinc electrodeposits obtained at constant T{sub ON} and I{sub P} enhanced (i.e., low I{sub corr} and high R{sub ct} values) with increased T{sub OFF}. At constant T{sub OFF} and I{sub P}, the I{sub corr} values increased and R{sub ct} values decreased with T{sub ON} while the former decreases and latter increases with I{sub P} at constant T{sub ON} and T{sub OFF}. The inclusion of primary and secondary additives into the electrolyte produced nc zinc electrodeposits at 5 Adm{sup -2}, showed enhanced protective properties (I{sub corr}-16 {mu}A cm{sup -2} and R{sub ct}-481.8 {Omega} cm{sup -2}). Fine grained due to high negative overpotential, reduced roughness and higher percentage of basal plane [0 0. 2] orientation have major impact for the enhanced corrosion resistances.
J. M. Dick
2006-01-01
Full Text Available Thermodynamic calculations can be used to quantify environmental constraints on the speciation of proteins, such as the pH and temperature dependence of ionization state, and the relative chemical stabilities of proteins in different biogeochemical settings. These calculations depend in part on values of the standard molal Gibbs energies of proteins and their ionization reactions as a function of temperature and pressure. Because these values are not generally available, we calculated values of the standard molal thermodynamic properties at 25°C and 1 bar as well as the revised Helgeson-Kirkham-Flowers equations of state parameters of neutral and charged zwitterionic reference model compounds including aqueous amino acids, polypeptides, and unfolded proteins. The experimental calorimetric and volumetric data for these species taken from the literature were combined with group additivity algorithms to calculate the properties and parameters of neutral and ionized sidechain and backbone groups in unfolded proteins. The resulting set of group contributions enables the calculation of the standard molal Gibbs energy, enthalpy, entropy, isobaric heat capacity, volume, and isothermal compressibility of unfolded proteins in a range of proton ionization states to temperatures and pressures exceeding 100°C and 1000 bar. This approach provides a useful frame of reference for thermodynamic studies of protein folding and complexation reactions. It can also be used to assign provisional values of the net charge and Gibbs energy of ionized proteins as a function of temperature and pH. Using these values, an Eh-pH diagram for a reaction representing the speciation of extracellular proteins from Pyrococcus furiosus and Bacillus subtilis was generated. The predicted predominance limits of these proteins correspond with the different electrochemical conditions of hydrothermal vents and soils. More comprehensive calculations of this kind may reveal pervasive
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...... experimentation. Our results show that constraint differentiation substantially reduces search and considerably improves the performance of OFMC, enabling its application to a wider class of problems....
Constraints on Anaphoric Determiners
Zuber, Richard
2010-01-01
Some constraints on functions from sets and relations to sets are studied. Such constraints are satisﬁed by anaphoric functions, that is functions denoted by anaphoric determiners. These constraints are generalisations of anaphor conditions known from the study of simpler cases of nominal anaphors. In addition a generalisation of the notion of conservativity as applied to anaphoric functions is proposed. Two classes of anaphoric determiners found in NLs are discussed as examples.
Removing Propagation Redundant Constraints in Redundant Modeling
Choi, Chiu Wo; Lee, Jimmy Ho-Man; Stuckey, Peter J.
2004-01-01
A widely adopted approach to solving constraint satisfaction problems combines systematic tree search with various degrees of constraint propagation for pruning the search space. One common technique to improve the execution efficiency is to add redundant constraints, which are constraints logically implied by others in the problem model. However, some redundant constraints are propagation redundant and hence do not contribute additional propagation information to the constraint solver. Redun...
Software Architecture: Architecture Constraints
Tibermacine, Chouki
2014-01-01
International audience In this chapter, we introduce an additional, yet essential, concept in describing software architectures : architecture constraints. We explain the precise role of these entities and their importance in object-oriented, component-based or service-oriented software engi-neering. We then describe the way in which they are specified and interpreted. An architect can define architecture constraints and then associate them to architectural descriptions to limit their stru...
Fallon, Richard Henry
2009-01-01
The main ambition of "Constitutional Constraints" is to open up the subject of constitutional constraints on government officials, including Presidents and Supreme Court Justices, as a topic for discussion within the field of Constitutional Theory. The subject has so far received little comprehensive discussion in the law reviews, in part because of a division between scholarly approaches that treat constitutional law as a system of norms and political scientific theories that portray judges ...
Raunhardt, Daniel; Boulic, Ronan
2009-01-01
In this paper, we propose a hybrid postural control approach taking advantage of data-driven and goal-oriented methods while overcoming their limitations. In particular, we take advantage of the latent space characterizing a given motion database. We introduce a motion constraint operating in the latent space to benefit from its much smaller dimension compared to the joint space. This allows its transparent integration into a Prioritized Inverse Kinematics framework. If its priority is high t...
Morphological Disambiguation by Voting Constraints
Oflazer, K; Oflazer, Kemal; Tur, Gokhan
1997-01-01
We present a constraint-based morphological disambiguation system in which individual constraints vote on matching morphological parses, and disambiguation of all the tokens in a sentence is performed at the end by selecting parses that receive the highest votes. This constraint application paradigm makes the outcome of the disambiguation independent of the rule sequence, and hence relieves the rule developer from worrying about potentially conflicting rule sequencing. Our results for disambiguating Turkish indicate that using about 500 constraint rules and some additional simple statistics, we can attain a recall of 95-96% and a precision of 94-95% with about 1.01 parses per token. Our system is implemented in Prolog and we are currently investigating an efficient implementation based on finite state transducers.
Data assimilation with inequality constraints
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.
The Soft Cumulative Constraint
Petit, Thierry
2009-01-01
This research report presents an extension of Cumulative of Choco constraint solver, which is useful to encode over-constrained cumulative problems. This new global constraint uses sweep and task interval violation-based algorithms.
Optimality criteria design and stress constraint processing
Levy, R.
1982-01-01
Methods for pre-screening stress constraints into either primary or side-constraint categories are reviewed; a projection method, which is developed from prior cycle stress resultant history, is introduced as an additional screening parameter. Stress resultant projections are also employed to modify the traditional stress-ratio, side-constraint boundary. A special application of structural modification reanalysis is applied to the critical stress constraints to provide feasible designs that are preferable to those obtained by conventional scaling. Sample problem executions show relatively short run times and fewer design cycle iterations to achieve low structural weights; those attained are comparable to the minimum values developed elsewhere.
Mathieu, Philippe; Keisu, Torbjörn
1990-01-01
This short note aims to present foundations for constraint logic programming. By logic programming, we understand in this paper the PROLOG paradigm. But it will be clear that we do reduce the problem to adding a new package to PROLOG. We argue that constraint logic programming should be defined as a new paradigm for programming: the LOGIC PROGRAMMING + SYMBOLIC COMPUTATION paradigm. Our system incorporates as a very basic, all the existing systems incorporating constraints i...
Memoization of Coroutined Constraints
Johnson, M; Johnson, Mark; Dörre, Jochen
1995-01-01
Some linguistic constraints cannot be effectively resolved during parsing at the location in which they are most naturally introduced. This paper shows how constraints can be propagated in a memoizing parser (such as a chart parser) in much the same way that variable bindings are, providing a general treatment of constraint coroutining in memoization. Prolog code for a simple application of our technique to Bouma and van Noord's (1994) categorial grammar analysis of Dutch is provided.
... this page: //medlineplus.gov/ency/article/002435.htm Food additives To use the sharing features on this page, please enable JavaScript. Food additives are substances that become part of a food ...
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....
Credit Constraints in Education
Lochner, Lance; Monge-Naranjo, Alexander
2012-01-01
We review studies of the impact of credit constraints on the accumulation of human capital. Evidence suggests that credit constraints have recently become important for schooling and other aspects of households' behavior. We highlight the importance of early childhood investments, as their response largely determines the impact of credit…
Creating Positive Task Constraints
Mally, Kristi K.
2006-01-01
Constraints are characteristics of the individual, the task, or the environment that mold and shape movement choices and performances. Constraints can be positive--encouraging proficient movements or negative--discouraging movement or promoting ineffective movements. Physical educators must analyze, evaluate, and determine the effect various…
Evaluating Distributed Timing Constraints
Kristensen, C.H.; Drejer, N.
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....
Constraint Reasoning Over Strings
Koga, Dennis (Technical Monitor); Golden, Keith; Pang, Wanlin
2003-01-01
This paper discusses an approach to representing and reasoning about constraints over strings. We discuss how many string domains can often be concisely represented using regular languages, and how constraints over strings, and domain operations on sets of strings, can be carried out using this representation.
Tuggy, David
This paper presents a class of sentences that certain syntactic rules of English would be expected to produce, but that are not grammatical. The sentences all involve the raising of a sentential Noun Phrase (NP) and the subsequent application of some syntactic rule to that senential NP. A constraint, referred to as the Antigone Constraint, is…
Temporal Concurrent Constraint Programming
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...
Relationship between protein structure and geometrical constraints
Lund, Ole; Hansen, Jan; Brunak, Søren; Bohr, Jakob
1996-01-01
We evaluate to what extent the structure of proteins can be deduced from incomplete knowledge of disulfide bridges, surface assignments, secondary structure assignments, and additional distance constraints. A cost function taking such constraints into account was used to obtain protein structures...... using a simple minimization algorithm. For small proteins, the approximate structure could be obtained using one additional distance constraint for each amino acid in the protein. We also studied the effect of using predicted secondary structure and surface assignments. The constraints used in this...... approach typically may be obtained from low-resolution experimental data. When using a cost function based on distances, half of the resulting structures will be mirrored, because the resulting structure and its mirror image will have the same cost. The secondary structure assignments were therefore...
Network Design with Node Degree Balance Constraints
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 ...... applications within the design of transportation networks. The model is solved using a Tabu Search heuristic using a hybrid of the add/drop procedure and cycle-based neighbourhoods....
Stochastic Image Registration with User Constraints
Kolesov, Ivan; Lee, JeHoon; Vela, Patricio; Tannenbaum, Allen
2013-01-01
Constrained registration is an active area of research and is the focus of this work. This note describes a non-rigid image registration framework for incorporating landmark constraints. Points that must remain stationary are selected, the user chooses the spatial extent of the inputs, and an automatic step computes the deformable registration, respecting the constraints. Parametrization of the deformation field is by an additive composition of a similarity transformation and a set of Gaussia...
Kernels for Global Constraints
Gaspers, Serge
2011-01-01
Bessiere et al. (AAAI'08) showed that several intractable global constraints can be efficiently propagated when certain natural problem parameters are small. In particular, the complete propagation of a global constraint is fixed-parameter tractable in k - the number of holes in domains - whenever bound consistency can be enforced in polynomial time; this applies to the global constraints AtMost-NValue and Extended Global Cardinality (EGC). In this paper we extend this line of research and introduce the concept of reduction to a problem kernel, a key concept of parameterized complexity, to the field of global constraints. In particular, we show that the consistency problem for AtMost-NValue constraints admits a linear time reduction to an equivalent instance on O(k^2) variables and domain values. This small kernel can be used to speed up the complete propagation of NValue constraints. We contrast this result by showing that the consistency problem for EGC constraints does not admit a reduction to a polynomial...
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.
A constraint algorithm for singular Lagrangians subjected to nonholonomic constraints
We construct a constraint algorithm for singular Lagrangian systems subjected to nonholonomic constraints which generalizes that of Dirac for constrained Hamiltonian systems. copyright 1997 American Institute of Physics
New Constraints on Additional Satellites of the Pluto System
Steffl, A. J.; Mutchler, M. J.; Weaver, H. A.; Stern, S. A.; Durda, D. D.; Terrell, D.; Merline, W. J.; Young, L. A.; Young, E. F; Buie, M. W.; Spencer, J. R.
2005-01-01
Observations of Pluto and its solar-tidal stability zone were made using the Advanced Camera for Surveys' (ACS) Wide Field Channel (WFC) on the Hubble Space Telescope on UT 2005 May 15 and UT 2005 May 18. Two small satellites of Pluto, provisionally designated S/2005 P 1 and S/2005 P 2, were discovered, as discussed by Weaver et al. (2006) and Stern et al. (2006a). Confirming observations of the newly discovered moons were obtained using the ACS in the High Resolution Channel (HRC) mode on 20...
Dynamics and causality constraints
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)
Dynamics and causality constraints
De Souza, M M
2000-01-01
The physical meaning and the geometrical interpretation of causality implementation in classical field theories are discussed. Local causality are kinematical constraints dynamically implemented via solutions of the field equations, 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 and implies on deep implications to the nature of physical interactions.
Essays on Collateral Constraints
Brumm, Johannes
2011-01-01
This thesis consists of three self-contained papers. Chapter 1 provides a general introduction. In Chapter 2, I study the impact of collateral constraints on producers and thereby on aggregate output. In a theoretical paper, Kiyotaki and Moore (1997) show that collateral constraints that restrict the investment decisions of producers can strongly amplify and propagate aggregate shocks. However, the subsequent quantitative literature tends to find rather weak and non-robust effects of collater...
Temporal Concurrent Constraint Programming
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....... Furthermore, the expressive power of this fragment is illustrated by examples. Basic Research in Computer Science, Centre of the Danish National Research Foundation....
Paul Rozin
2009-10-01
Full Text Available Judgments of naturalness of foods tend to be more influenced by the process history of a food, rather than its actual constituents. Two types of processing of a ``natural'' food are to add something or to remove something. We report in this study, based on a large random sample of individuals from six countries (France, Germany, Italy, Switzerland, UK and USA that additives are considered defining features of what makes a food not natural, whereas ``subtractives'' are almost never mentioned. In support of this, skim milk (with major subtraction of fat is rated as more natural than whole milk with a small amount of natural vitamin D added. It is also noted that ``additives'' is a common word, with a synonym reported by a native speaker in 17 of 18 languages, whereas ``subtractive'' is lexicalized in only 1 of the 18 languages. We consider reasons for additivity dominance, relating it to omission bias, feature positive bias, and notions of purity.
Misconceptions and constraints
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)
Psychological constraints on egalitarianism
Kasperbauer, Tyler Joshua
2015-01-01
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...... 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 are...
Paul Rozin; Claude Fischler; Christy Shields-Argeles
2009-01-01
Judgments of naturalness of foods tend to be more influenced by the process history of a food, rather than its actual constituents. Two types of processing of a ``natural'' food are to add something or to remove something. We report in this study, based on a large random sample of individuals from six countries (France, Germany, Italy, Switzerland, UK and USA) that additives are considered defining features of what makes a food not natural, whereas ``subtractives'' are almost never mentioned....
Constraint-based scheduling applying constraint programming to scheduling problems
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...
Ecosystems emerging. 5: Constraints
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
Reduction of Constraints: Applicability of the Homogeneity Constraint for Macrobatch 3
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
Segmentation with Area Constraints
Niethammer, Marc; Zach, Christopher
2012-01-01
Image segmentation approaches typically incorporate weak regularity conditions such as boundary length or curvature terms, or use shape information. High-level information such as a desired area or volume, or a particular topology are only implicitly specified. In this paper we develop a segmentation method with explicit bounds on the segmented area. Area constraints allow for the soft selection of meaningful solutions, and can counteract the shrinking bias of length-based regularization. We ...
Overcoming Participation Constraints
Hanming Fang; Peter Norman
2005-01-01
In incomplete information environments with transferable utility, efficient outcomes are generally implementable unless interim or ex post participation constraints are imposed on the problem. In this paper we show that linking a sufficiently large number of independent but possibly unrelated social decisions, a slightly perturbed Groves mechanism can implement an efficient outcome with probability arbitrarily close to one, while respecting all participation, incentive and balanced budget con...
The NCL natural constraint language
Zhou, Jianyang
2012-01-01
This book presents the Natural Constraint Language (NCL) language, a description language in conventional mathematical logic for modeling and solving constraint satisfaction problems. It uses illustrations and tutorials to detail NCL and its applications.
Memoization in Constraint Logic Programming
Johnson, Mark
1994-01-01
This paper shows how to apply memoization (caching of subgoals and associated answer substitutions) in a constraint logic programming setting. The research is is motivated by the desire to apply constraint logic programming (CLP) to problems in natural language processing that involve (constraint) interleaving or coroutining, such as GB and HPSG parsing.
Constraints on Rindler Hydrodynamics
Meyer, Adiel
2013-01-01
We study uncharged Rindler hydrodynamics at second order in the derivative expansion. The equation of state of the theory is given by a vanishing equilibrium energy density. We derive relations among the transport coefficients by employing two frameworks. First, by the requirement of having an entropy current with a non-negative divergence, second by studying the thermal partition function on stationary backgrounds. The relations derived by these two methods are consistent with each other. However, we find that the entropy current yields stronger constraints than the thermal partition function. We verify the results by studying explicit examples in flat and curved space-time geometries.
Temporal Concurrent Constraint Programming
Valencia, Frank Dan
Concurrent constraint programming (ccp) is a formalism for concurrency in which agents interact with one another by telling (adding) and asking (reading) information in a shared medium. Temporal ccp extends ccp by allowing agents to be constrained by time conditions. This dissertation studies...... structures, robotic devises, multi-agent systems and music applications. The calculus is provided with a denotational semantics that captures the reactive computations of processes in the presence of arbitrary environments. The denotation is proven to be fully-abstract for a substantial fragment...
Higher derivative theories with constraints: exorcising Ostrogradski's ghost
We prove that the linear instability in a non-degenerate higher derivative theory, the Ostrogradski instability, can only be removed by the addition of constraints if the original theory's phase space is reduced
Asteroseismic constraints for Gaia
Creevey, O L
2012-01-01
Distances from the Gaia mission will no doubt improve our understanding of stellar physics by providing an excellent constraint on the luminosity of the star. However, it is also clear that high precision stellar properties from, for example, asteroseismology, will also provide a needed input constraint in order to calibrate the methods that Gaia will use, e.g. stellar models or GSP_phot. For solar-like stars (F, G, K IV/V), asteroseismic data delivers at the least two very important quantities: (1) the average large frequency separation and (2) the frequency corresponding to the maximum of the modulated-amplitude spectrum nu_max. Both of these quantities are related directly to stellar parameters (radius and mass) and in particular their combination (gravity and density). We show how the precision in , nu_max, and atmospheric parameters T_eff and [Fe/H] affect the determination of gravity (log g) for a sample of well-known stars. We find that log g can be determined within less than 0.02 dex accuracy for ou...
Searching for genomic constraints
The authors have analyzed general properties of very long DNA sequences belonging to simple and complex organisms, by using different correlation methods. They have distinguished those base compositional rules that concern the entire genome which they call 'genomic constraints' from the rules that depend on the 'external natural selection' acting on single genes, i. e. protein-centered constraints. They show that G + C content, purine / pyrimidine distributions and biological complexity of the organism are the most important factors which determine base compositional rules and genome complexity. Three main facts are here reported: bacteria with high G + C content have more restrictions on base composition than those with low G + C content; at constant G + C content more complex organisms, ranging from prokaryotes to higher eukaryotes (e.g. human) display an increase of repeats 10-20 nucleotides long, which are also partly responsible for long-range correlations; work selection of length 3 to 10 is stronger in human and in bacteria for two distinct reasons. With respect to previous studies, they have also compared the genomic sequence of the archeon Methanococcus jannaschii with those of bacteria and eukaryotes: it shows sometimes an intermediate statistical behaviour
Design with Nonlinear Constraints
Tang, Chengcheng
2015-12-10
Most modern industrial and architectural designs need to satisfy the requirements of their targeted performance and respect the limitations of available fabrication technologies. At the same time, they should reflect the artistic considerations and personal taste of the designers, which cannot be simply formulated as optimization goals with single best solutions. This thesis aims at a general, flexible yet e cient computational framework for interactive creation, exploration and discovery of serviceable, constructible, and stylish designs. By formulating nonlinear engineering considerations as linear or quadratic expressions by introducing auxiliary variables, the constrained space could be e ciently accessed by the proposed algorithm Guided Projection, with the guidance of aesthetic formulations. The approach is introduced through applications in different scenarios, its effectiveness is demonstrated by examples that were difficult or even impossible to be computationally designed before. 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 is extended to developable surfaces including origami with curved creases. Finally, general approaches to extend hard constraints and soft energies are discussed, followed by a concluding remark outlooking possible future studies.
Cosmographic Constraints and Cosmic Fluids
Salvatore Capozziello
2013-12-01
Full Text Available The problem of reproducing dark energy effects is reviewed here with particular interest devoted to cosmography. We summarize some of the most relevant cosmological models, based on the assumption that the corresponding barotropic equations of state evolve as the universe expands, giving rise to the accelerated expansion. We describe in detail the ΛCDM (Λ-Cold Dark Matter and ωCDM models, considering also some specific examples, e.g., Chevallier–Polarsky–Linder, the Chaplygin gas and the Dvali–Gabadadze–Porrati cosmological model. Finally, we consider the cosmological consequences of f(R and f(T gravities and their impact on the framework of cosmography. Keeping these considerations in mind, we point out the model-independent procedure related to cosmography, showing how to match the series of cosmological observables to the free parameters of each model. We critically discuss the role played by cosmography, as a selection criterion to check whether a particular model passes or does not present cosmological constraints. In so doing, we find out cosmological bounds by fitting the luminosity distance expansion of the redshift, z, adopting the recent Union 2.1 dataset of supernovae, combined with the baryonic acoustic oscillation and the cosmic microwave background measurements. We perform cosmographic analyses, imposing different priors on the Hubble rate present value. In addition, we compare our results with recent PLANCK limits, showing that the ΛCDM and ωCDM models seem to be the favorite with respect to other dark energy models. However, we show that cosmographic constraints on f(R and f(T cannot discriminate between extensions of General Relativity and dark energy models, leading to a disadvantageous degeneracy problem.
Constraint Propagation as Information Maximization
Abdallah, A Nait
2012-01-01
Dana Scott used the partial order among partial functions for his mathematical model of recursively defined functions. He interpreted the partial order as one of information content. In this paper we elaborate on Scott's suggestion of regarding computation as a process of information maximization by applying it to the solution of constraint satisfaction problems. Here the method of constraint propagation can be interpreted as decreasing uncertainty about the solution -- that is, as gain in information about the solution. As illustrative example we choose numerical constraint satisfaction problems to be solved by interval constraints. To facilitate this approach to constraint solving we formulate constraint satisfaction problems as formulas in predicate logic. This necessitates extending the usual semantics for predicate logic so that meaning is assigned not only to sentences but also to formulas with free variables.
Constraints On Cosmic Dynamics
Mbonye, M R
2003-01-01
Observationally, the universe appears virtually critical. Yet, there is no simple explanation for this state. In this article we advance and explore the premise that the dynamics of the universe always seeks equilibrium conditions. Vacuum-induced cosmic accelerations lead to creation of matter-energy modes at the expense of vacuum energy. Because they gravitate, such modes constitute inertia against cosmic acceleration. On the other extreme, the would-be ultimate phase of local gravitational collapse is checked by a phase transition in the collapsing matter fields leading to a de Sitter-like fluid deep inside the black hole horizon, and at the expense of the collapsing matter fields. As a result, the universe succumbs to neither vacuum-induced run-away accelerations nor to gravitationally induced spacetime curvature singularities. Cosmic dynamics is self-regulating. We discuss the physical basis for these constraints and the implications, pointing out how the framework relates and helps resolve standing puzzl...
Collateral constraints and macroeconomic asymmetries
Luca Guerrieri; Matteo Iacoviello
2013-01-01
We show that a simple macroeconomic model with collateral constraints displays strong asymmetric responses to boom and bust periods. In a boom triggered by a rise in asset values, constraints become more and more relaxed, the collateral channel is weaker, and the response of aggregate consumption (and output) to a wealth shock is positive but small. In a recession, collateral constraints get tighter and tighter, the collateral channel gets stronger, and the response in consumption from a give...
Adaptive constraints for feature tracking
K. I. Hodges
1999-01-01
In this paper extensions to an existing tracking algorithm are described. These extensions implement adaptive tracking constraints in the form of regional upper-bound displacements and an adaptive track smoothness constraint. Together, these constraints make the tracking algorithm more flexible than the original algorithm (which used fixed tracking parameters) and provide greater confidence in the tracking results. The result of applying the new algorithm to high-resolution ...
Principles of Constraint Programming and Constraint Processing: A Review
Van Der Beek, Peter; Walsh, Toby
2004-01-01
Review of Apt, Krzysztof. "Principles of Constraint Programming. Cambridge, England: Cambridge University Press. ISBN: 0- 521-825830. 420 pages, $50.00. Publication Date: August 2003. Review also of Dechter, Rina. "Constraint Processing. San Francisco: Morgan Kaufmann Publishers. ISBN 1-55860-890-7. 481 pages, $65.95. Publication Date: May 2003.
Sustainability constraints on UK bioenergy development
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. (author)
Generalizing Consistency and other Constraint Properties to Quantified Constraints
Bordeaux, Lucas; Mancini, Toni
2007-01-01
Quantified constraints and Quantified Boolean Formulae are typically much more difficult to reason with than classical constraints, because quantifier alternation makes the usual notion of solution inappropriate. As a consequence, basic properties of Constraint Satisfaction Problems (CSP), such as consistency or substitutability, are not completely understood in the quantified case. These properties are important because they are the basis of most of the reasoning methods used to solve classical (existentially quantified) constraints, and one would like to benefit from similar reasoning methods in the resolution of quantified constraints. In this paper, we show that most of the properties that are used by solvers for CSP can be generalized to quantified CSP. This requires a re-thinking of a number of basic concepts; in particular, we propose a notion of outcome that generalizes the classical notion of solution and on which all definitions are based. We propose a systematic study of the relations which hold be...
Nonlinear balance constraints in 3DVAR data assimilation
ZHU; Jiang; YAN; Changxiang
2006-01-01
In many applications of 3DVAR, the balance constraints can be considered via two main approaches: weak constraint method which adds penalty terms to the cost function; and proper definition of the background error covariance matrix with non-zero cross-correlation sub-matrices. The weak constraint approach requires determining the weighting matrices of the penalty terms. The background error covariance approach does not require determining those additional weighting matrices. However, it is only applicable to those linear or linearized balance constraints. A novel approach is proposed based on the background error covariance approach by generalizing the so-called Derber-Bouttier formulation. An assimilation experiment of estimating temperature and salinity from the sea surface dynamic height observation is given to illustrate the proposed treatments of nonlinear balance constraints.
Credit Constraints for Higher Education
Solis, Alex
2012-01-01
This paper exploits a natural experiment that produces exogenous variation on credit access to determine the effect on college enrollment. The paper assess how important are credit constraints to explain the gap in college enrollment by family income, and what would be the gap if credit constraints are eliminated. Progress in college and dropout…
Minimal Flavor Constraints for Technicolor
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...
CONCURRENT ENGINEERING WITH CONSTRAINT NETWORKS
Steve Minnaar; Robert Reinecke
2012-01-01
Concurrent engineering is a systematic approach to the integrated, concurrent design of products and their related processes, including manufacture and support. It allows the consideration of all elements of the product's life cycle, from conception through disposal, including quality, cost, manufacturing, and customer requirements. Constraint networks as an approach to concurrent engineering provides considerable advantages over the conventional approaches to improve engineering. Constraint ...
An Introduction to 'Creativity Constraints'
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...
Constraint Programming for Context Comprehension
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...
Optimizing selection with several constraints in poultry breeding.
Chapuis, H; Pincent, C; Colleau, J J
2016-02-01
Poultry breeding schemes permanently face the need to control the evolution of coancestry and some critical traits, while selecting for a main breeding objective. The main aims of this article are first to present an efficient selection algorithm adapted to this situation and then to measure how the severity of constraints impacted on the degree of loss for the main trait, compared to BLUP selection on the main trait, without any constraint. Broiler dam and sire line schemes were mimicked by simulation over 10 generations and selection was carried out on the main trait under constraints for coancestry and for another trait, antagonistic with the main trait. The selection algorithm was a special simulated annealing (adaptative simulated annealing (ASA)). It was found to be rapid and able to meet constraints very accurately. A constraint on the second trait was found to induce an impact similar to or even greater than the impact of the constraint on coancestry. The family structure of selected poultry populations made it easy to control the evolution of coancestry at a reasonable cost but was not as useful for reducing the cost of controlling evolution of the antagonistic traits. Multiple constraints impacted almost additively on the genetic gain for the main trait. Adding constraints for several traits would therefore be justified in real life breeding schemes, possibly after evaluating their impact through simulated annealing. PMID:26220593
Infrared Kuiper Belt Constraints
We compute the temperature and IR signal of particles of radius a and albedo α at heliocentric distance R, taking into account the emissivity effect, and give an interpolating formula for the result. We compare with analyses of COBE DIRBE data by others (including recent detection of the cosmic IR background) for various values of heliocentric distance R, particle radius a, and particle albedo α. We then apply these results to a recently developed picture of the Kuiper belt as a two-sector disk with a nearby, low-density sector (40< R<50 endash 90 AU) and a more distant sector with a higher density. We consider the case in which passage through a molecular cloud essentially cleans the solar system of dust. We apply a simple model of dust production by comet collisions and removal by the Poynting-Robertson effect to find limits on total and dust masses in the near and far sectors as a function of time since such a passage. Finally, we compare Kuiper belt IR spectra for various parameter values. Results of this work include: (1) numerical limits on Kuiper belt dust as a function of (R, a, α) on the basis of four alternative sets of constraints, including those following from recent discovery of the cosmic IR background by Hauser et al.; (2) application to the two-sector Kuiper belt model, finding mass limits and spectrum shape for different values of relevant parameters including dependence on time elapsed since last passage through a molecular cloud cleared the outer solar system of dust; and (3) potential use of spectral information to determine time since last passage of the Sun through a giant molecular cloud. copyright copyright 1999. The American Astronomical Society
Vocabulary Constraint on Texts
C. Sutarsyah
2008-01-01
Full Text Available This case study was carried out in the English Education Department of State University of Malang. The aim of the study was to identify and describe the vocabulary in the reading text and to seek if the text is useful for reading skill development. A descriptive qualitative design was applied to obtain the data. For this purpose, some available computer programs were used to find the description of vocabulary in the texts. It was found that the 20 texts containing 7,945 words are dominated by low frequency words which account for 16.97% of the words in the texts. The high frequency words occurring in the texts were dominated by function words. In the case of word levels, it was found that the texts have very limited number of words from GSL (General Service List of English Words (West, 1953. The proportion of the first 1,000 words of GSL only accounts for 44.6%. The data also show that the texts contain too large proportion of words which are not in the three levels (the first 2,000 and UWL. These words account for 26.44% of the running words in the texts.Â It is believed that the constraints are due to the selection of the texts which are made of a series of short-unrelated texts. This kind of text is subject to the accumulation of low frequency words especially those of content words and limited of words from GSL. It could also defeat the development of students' reading skills and vocabulary enrichment.
Automated constraint placement to maintain pile shape
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.
Constraint-Aided Product Design
G. Mullineux
2005-01-01
Full Text Available The importance of supporting the early stages of design is widely accepted. In particular, the development of supportive tools and methods for modelling and analysis of evolving design solutions present a difficult challenge. One reason for this is the need to model both the product design and the design knowledge from which the design is created. There are a number of limitations with many existing techniques and an alternative approach that deals with the design constraints themselves is presented. Dealing directly with the constraints affords a more generalised approach that represents the process by which a product is designed. This enables modelling and reasoning about a product from an often abstract and evolving set of requirements. The constraint methodology is an iterative process where the design requirements are elaborated, the constraint rules altered, design ideas generated and tested as functional structures. The incorporation of direct search techniques to solve the constrained problem enables different solutions to be explored and allows the determination of ‘best compromises’ for related constraints. A constraint modelling environment is discussed and two example cases are used to demonstrate the potential of a constraint-aided approach for supporting important issues such as the design of product variants and product families.
Constraint Embedding Technique for Multibody System Dynamics
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
A Comparative Study of Randomized Constraint Solvers for Random-Symbolic Testing
Takaki, Mitsuo; Cavalcanti, Diego; Gheyi, Rohit; Iyoda, Juliano; dAmorim, Marcelo; Prudencio, Ricardo
2009-01-01
The complexity of constraints is a major obstacle for constraint-based software verification. Automatic constraint solvers are fundamentally incomplete: input constraints often build on some undecidable theory or some theory the solver does not support. This paper proposes and evaluates several randomized solvers to address this issue. We compare the effectiveness of a symbolic solver (CVC3), a random solver, three hybrid solvers (i.e., mix of random and symbolic), and two heuristic search solvers. We evaluate the solvers on two benchmarks: one consisting of manually generated constraints and another generated with a concolic execution of 8 subjects. In addition to fully decidable constraints, the benchmarks include constraints with non-linear integer arithmetic, integer modulo and division, bitwise arithmetic, and floating-point arithmetic. As expected symbolic solving (in particular, CVC3) subsumes the other solvers for the concolic execution of subjects that only generate decidable constraints. For the remaining subjects the solvers are complementary.
A methodology for controlling motion and constraint forces in holonomically constrained systems
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.
Expressing Preferences using Preference Set Constraint Atoms
Brik, Alex; Remmel, Jeffrey B.
2012-01-01
This paper introduces an extension of Answer Set Programming called Preference Set Constraint Programming which is a convenient and general formalism to reason with preferences. PSC programming extends Set Constraint Programming introduced by Marek and Remmel (Marek and Remmel 2004) by introducing two types of preference set constraint atoms, measure preference set constraint atoms and pre-ordered preference set constraint atoms, which are extensions of set constraint atoms. We show that the ...
SMEs, financial constraints and growth
Ryan Banerjee
2014-01-01
The SME sector is often hailed as an important engine of economic growth. But recent research suggests that young rather than small firms are the main contributors to employment growth. This paper shows that young firms are also key contributors to profit growth across advanced economies. It them examines the impact of financial constraints on profitability across the age distribution of SMEs. We find that start-ups which report finance as their greatest constraint receive smaller new loans a...
Developmental constraints on behavioural flexibility
Holekamp, Kay E.; Swanson, Eli M.; Van Meter, Page E.
2013-01-01
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 spotte...
Collateral constraints and rental markets
D'Albis, Hippolyte; Iliopulos, Eleni
2013-01-01
International audience We study a benchmark model with collateral constraints and heterogeneous discounting. Contrarily to a rich literature on borrowing limits, we allow for rental markets. By incorporating this missing market, we show that impatient agents choose to rent rather than to own the collateral in the neighborhood of the deterministic steady state. Consequently, impatient agents are not indebted and borrowing constraints play no role in local dynamics.
Financial Constraints on Corporate Goodness
Harrison Hong; Kubik, Jeffrey D.; Jose A. Scheinkman
2012-01-01
An influential thesis, dubbed "Doing well by doing good," argues that corporate social responsibility is profitable. But heterogeneity in firm financial constraints can induce a spurious correlation between profits and goodness even if the motives for goodness are non-profit in nature. We use two identification strategies to show that financial constraints are indeed an important driver of corporate goodness. First, during the Internet bubble, previously constrained firms experienced a tempor...
Formal Verification under Unknown Constraints
LI Guang-hui; LI Xiao-wei
2005-01-01
We present a formal method of verifying designs with unknown constraints (e. g. , black boxes) using Boolean satisfiability (SAT). This method is based on a new encoding scheme of unknown constraints, and solves the corresponding conjunctive normal form (CNF) formulas. Furthermore, this method can avoid the potential memory explosion, which the binary decision diagram (BDD) based techniques maybe suffer from, thus it has the capacity of verifying large designs. Experimental results demonstrate the efficiency and feasibility of the proposed method.
Foundations of support constraint machines.
Gnecco, Giorgio; Gori, Marco; Melacci, Stefano; Sanguineti, Marcello
2015-02-01
The mathematical foundations of a new theory for the design of intelligent agents are presented. The proposed learning paradigm is centered around the concept of constraint, representing the interactions with the environment, and the parsimony principle. The classical regularization framework of kernel machines is naturally extended to the case in which the agents interact with a richer environment, where abstract granules of knowledge, compactly described by different linguistic formalisms, can be translated into the unified notion of constraint for defining the hypothesis set. Constrained variational calculus is exploited to derive general representation theorems that provide a description of the optimal body of the agent (i.e., the functional structure of the optimal solution to the learning problem), which is the basis for devising new learning algorithms. We show that regardless of the kind of constraints, the optimal body of the agent is a support constraint machine (SCM) based on representer theorems that extend classical results for kernel machines and provide new representations. In a sense, the expressiveness of constraints yields a semantic-based regularization theory, which strongly restricts the hypothesis set of classical regularization. Some guidelines to unify continuous and discrete computational mechanisms are given so as to accommodate in the same framework various kinds of stimuli, for example, supervised examples and logic predicates. The proposed view of learning from constraints incorporates classical learning from examples and extends naturally to the case in which the examples are subsets of the input space, which is related to learning propositional logic clauses. PMID:25380338
Phonotactic Constraints Are Activated across Languages in Bilinguals
Freeman, Max R.; Blumenfeld, Henrike K.; Marian, Viorica
2016-01-01
During spoken language comprehension, auditory input activates a bilingual’s two languages in parallel based on phonological representations that are shared across languages. However, it is unclear whether bilinguals access phonotactic constraints from the non-target language during target language processing. For example, in Spanish, words with s+ consonant onsets cannot exist, and phonotactic constraints call for epenthesis (addition of a vowel, e.g., stable/estable). Native Spanish speakers may produce English words such as estudy (“study”) with epenthesis, suggesting that these bilinguals apply Spanish phonotactic constraints when speaking English. The present study is the first to examine whether bilinguals access Spanish phonotactic constraints during English comprehension. In an English cross-modal priming lexical decision task, Spanish–English bilinguals and English monolinguals heard English cognate and non-cognate primes containing s+ consonant onsets or controls without s+ onsets, followed by a lexical decision on visual targets with the /e/ phonotactic constraint or controls without /e/. Results revealed that bilinguals were faster to respond to /es/ non-word targets preceded by s+ cognate primes and /es/ and /e/ non-word targets preceded by s+ non-cognate primes, confirming that English primes containing s+ onsets activated Spanish phonotactic constraints. These findings are discussed within current accounts of parallel activation of two languages during bilingual spoken language comprehension, which may be expanded to include activation of phonotactic constraints from the irrelevant language. PMID:27242615
Breaking evolutionary constraint with a tradeoff ratchet.
de Vos, Marjon G J; Dawid, Alexandre; Sunderlikova, Vanda; Tans, Sander J
2015-12-01
Epistatic interactions can frustrate and shape evolutionary change. Indeed, phenotypes may fail to evolve when essential mutations are only accessible through positive selection if they are fixed simultaneously. How environmental variability affects such constraints is poorly understood. Here, we studied genetic constraints in fixed and fluctuating environments using the Escherichia coli lac operon as a model system for genotype-environment interactions. We found that, in different fixed environments, all trajectories that were reconstructed by applying point mutations within the transcription factor-operator interface became trapped at suboptima, where no additional improvements were possible. Paradoxically, repeated switching between these same environments allows unconstrained adaptation by continuous improvements. This evolutionary mode is explained by pervasive cross-environmental tradeoffs that reposition the peaks in such a way that trapped genotypes can repeatedly climb ascending slopes and hence, escape adaptive stasis. Using a Markov approach, we developed a mathematical framework to quantify the landscape-crossing rates and show that this ratchet-like adaptive mechanism is robust in a wide spectrum of fluctuating environments. Overall, this study shows that genetic constraints can be overcome by environmental change and that cross-environmental tradeoffs do not necessarily impede but also, can facilitate adaptive evolution. Because tradeoffs and environmental variability are ubiquitous in nature, we speculate this evolutionary mode to be of general relevance. PMID:26567153
Reheating Constraints to Inflationary Models
Dai, Liang; Kamionkowski, Marc; Wang, Junpu
2014-07-01
Evidence from the BICEP2 experiment for a significant gravitational-wave background has focused attention on inflaton potentials V(ϕ)∝ϕα with α=2 ("chaotic" or "m2ϕ2" inflation) or with smaller values of α, as may arise in axion-monodromy models. Here we show that reheating considerations may provide additional constraints to these models. The reheating phase preceding the radiation era is modeled by an effective equation-of-state parameter wre. The canonical reheating scenario is then described by wre=0. The simplest α=2 models are consistent with wre=0 for values of ns well within the current 1σ range. Models with α=1 or α=2/3 require a more exotic reheating phase, with -1/31/3, unless ns is close to the lower limit of the 2σ range. For m2ϕ2 inflation and canonical reheating as a benchmark, we derive a relation log10(Tre/106 GeV)≃2000(ns-0.96) between the reheat temperature Tre and the scalar spectral index ns. Thus, if ns is close to its central value, then Tre≲106 GeV, just above the electroweak scale. If the reheat temperature is higher, as many theorists may prefer, then the scalar spectral index should be closer to ns≃0.965 (at the pivot scale k =0.05 Mpc-1), near the upper limit of the 1σ error range. Improved precision in the measurement of ns should allow m2ϕ2, axion monodromy, and ϕ4 models to be distinguished, even without precise measurement of r, and to test the m2ϕ2 expectation of ns≃0.965.
The Geometry of Algorithms with Orthogonality Constraints
Edelman, A; Smith, S T; Edelman, Alan; Smith, Steven T.
1998-01-01
In this paper we develop new Newton and conjugate gradient algorithms on the Grassmann and Stiefel manifolds. These manifolds represent the constraints that arise in such areas as the symmetric eigenvalue problem, nonlinear eigenvalue problems, electronic structures computations, and signal processing. In addition to the new algorithms, we show how the geometrical framework gives penetrating new insights allowing us to create, understand, and compare algorithms. The theory proposed here provides a taxonomy for numerical linear algebra algorithms that provide a top level mathematical view of previously unrelated algorithms. It is our hope that developers of new algorithms and perturbation theories will benefit from the theory, methods, and examples in this paper.
Constraint Databases and Geographic Information Systems
Revesz, Peter
2007-01-01
Constraint databases and geographic information systems share many applications. However, constraint databases can go beyond geographic information systems in efficient spatial and spatiotemporal data handling methods and in advanced applications. This survey mainly describes ways that constraint databases go beyond geographic information systems. However, the survey points out that in some areas constraint databases can learn also from geographic information systems.
Constraint programming and decision making
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...
Market dispatch incorporating stability constraints
Stability aspects have often been incorporated in the electricity market dispatch/pricing procedure using trial-and-error methods, or approximated in the dispatch optimisation directly as a set of linear constraints on generation/transmission. This paper presents the preliminary experiences with the development of a market optimal power flow (OPF) model that incorporates both transient and voltage stability constraints. The resultant dispatch and prices are expected to exhibit the impact of accurately modelled stability limits that are hitherto largely unknown. This model allows integrated representation of both voltage and transient stability. It, however, entails very significant computational complexities. A complete resolution of all these issues is beyond the scope of this paper, although some initial thoughts to simplify computation are discussed. The importance of stability constraints on market dispatch and prices is discussed around a simple 9-bus system example. (author)
Solving Functional Constraints by Variable Substitution
Zhang, Yuanlin
2010-01-01
Functional constraints and bi-functional constraints are an important constraint class in Constraint Programming (CP) systems, in particular for Constraint Logic Programming (CLP) systems. CP systems with finite domain constraints usually employ CSP-based solvers which use local consistency, for example, arc consistency. We introduce a new approach which is based instead on variable substitution. We obtain efficient algorithms for reducing systems involving functional and bi-functional constraints together with other non-functional constraints. It also solves globally any CSP where there exists a variable such that any other variable is reachable from it through a sequence of functional constraints. Our experiments on random problems show that variable elimination can significantly improve the efficiency of solving problems with functional constraints.
Introduction: Biological Constraints on Learning
Burgos, José E
2015-01-01
This special section stemmed from a symposium on biological constraints on learning that was organized for the XVII Biennial Meeting of the International Society for Comparative Psychology in Bogotá, Colombia, September 2014. The symposium sought to revisit the topic of biological constraints on learning. Such is the aim of this special section as well, guided by the conviction that the topic demands further study. Some of the most important researchers in the area were invited to contribu...
Evolutionary Constraints to Viroid Evolution
Santiago F. Elena
2009-09-01
Full Text Available We suggest that viroids are trapped into adaptive peaks as the result of adaptive constraints. The first one is imposed by the necessity to fold into packed structures to escape from RNA silencing. This creates antagonistic epistases, which make future adaptive trajectories contingent upon the first mutation and slow down the rate of adaptation. This second constraint can only be surpassed by increasing genetic redundancy or by recombination. Eigen’s paradox imposes a limit to the increase in genome complexity in the absence of mechanisms reducing mutation rate. Therefore, recombination appears as the only possible route to evolutionary innovation in viroids.
Soft liquidity constraints and precautionary saving
Emilio Fernandez-Corugedo
2002-01-01
The implications for consumption and saving behaviour are explored, when households are allowed to borrow, but face penalties which increase with the amount borrowed. It is shown that the introduction of this type of constraints (soft liquidity constraints) does not lead to consumers behaving very differently from consumers who face constraints which prevent them from borrowing at any time (hard liquidity constraints). However, when hard constraints are relaxed and become soft, the amount of ...
Weak Dynamic Programming for Generalized State Constraints
Bouchard, Bruno; Nutz, Marcel
2012-01-01
We provide a dynamic programming principle for stochastic optimal control problems with expectation constraints. A weak formulation, using test functions and a probabilistic relaxation of the constraint, avoids restrictions related to a measurable selection but still implies the Hamilton-Jacobi-Bellman equation in the viscosity sense. We treat open state constraints as a special case of expectation constraints and prove a comparison theorem to obtain the equation for closed state constraints.
Analysis of servo-constraint problems for underactuated multibody systems
R. Seifried
2013-02-01
Full Text Available Underactuated multibody systems have fewer control inputs than degrees of freedom. In trajectory tracking control of such systems an accurate and efficient feedforward control is often necessary. For multibody systems feedforward control by model inversion can be designed using servo-constraints. So far servo-constraints have been mostly applied to differentially flat underactuated mechanical systems. Differentially flat systems can be inverted purely by algebraic manipulations and using a finite number of differentiations of the desired output trajectory. However, such algebraic solutions are often hard to find and therefore the servo-constraint approach provides an efficient and practical solution method. Recently first results on servo-constraint problems of non-flat underactuated multibody systems have been reported. Hereby additional dynamics arise, so-called internal dynamics, yielding a dynamical system as inverse model. In this paper the servo-constraint problem is analyzed for both, differentially flat and non-flat systems. Different arising important phenomena are demonstrated using two illustrative examples. Also strategies for the numerical solution of servo-constraint problems are discussed.
Credit constraints and durable consumption
Herrala, Risto
2010-01-01
I find quantitative evidence of a significant effect for credit constraints on durable consumption during a post-deregulation consumer spending spree. The effect varied markedly across age and educational groups. Young households with low levels of education displayed high sensitivity to credit conditions. In contrast, older highly educated households were relatively immune to credit market developments.
An Introduction to 'Creativity Constraints'
Onarheim, Balder; Biskjaer, Michael Mose
, we give an overview of the growing, but incohesive body of research into creativity and constraints, which leads us to introduce ‘creativity constraints’ as a unifying concept to help bridge these disjoint contributions to facilitate cross- disciplinary interchange. Finally, we suggest key topics and...
Constraints on galaxy formation theories
Szalay, A. S.
1986-01-01
The present theories of galaxy formation are reviewed. The relation between peculiar velocities, temperature fluctuations of the microwave background and the correlation function of galaxies point to the possibility that galaxies do not form uniformly everywhere. The velocity data provide strong constraints on the theories even in the case when light does not follow mass of the universe.
Efficient Searching with Linear Constraints
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...... problem is called halfspace range searching in the computational geometry literature. Our goal is to minimize the number of disk blocks required to store the data structure and the number of disk accesses (I/Os) required to answer a query. For d=2, we present the first data structure that uses linear...... space and answers linear-constraint queries using an optimal number of I/Os in the worst case. For d=3, we present a near-linear-size data structure that answers queries using an optimal number of I/Os on the average. We present linear-size data structures that can answer d-dimensional linear...
Cultural Constraints on Literary Translation
Wei Lou
2009-01-01
Translation is no longer considered a single, unified reproduction of the original but a kind of rewriting which reflects a certain ideology and literary norm and literary translation is no exception. This essay tends to explore the cultural constraints on literary translation.
Intertemporal consumption and credit constraints
Leth-Petersen, Søren
2010-01-01
There is continuing controversy over the importance of credit constraints. This paper investigates whether total household expenditure and debt is affected by an exogenous increase in access to credit provided by a credit market reform that enabled Danish house owners to use housing equity as...
Credit Reporting and Financing Constraints
Love, Inessa; Mylenko, Nataliya
2003-01-01
The authors combine firm-level data from the World Bank Business Environment Survey (WBES) with data on private and public credit registries to investigate whether the presence of a credit registry in a country is associated with lower financing constraints, as perceived by managers, and with higher share of bank financing. They find that the existence of private credit registries is assoc...
Sterile neutrino constraints from cosmology
Hamann, Jan; Hannestad, Steen; Raffelt, Georg G.;
2012-01-01
The presence of light particles beyond the standard model's three neutrino species can profoundly impact the physics of decoupling and primordial nucleosynthesis. I review the observational signatures of extra light species, present constraints from recent data, and discuss the implications of po...... of possible sterile neutrinos with O(eV)-masses for cosmology....
Conjoined Constraints and Phonological Acquisition
Bonilha, Giovana
2003-01-01
Since the start of Optimality Theory (Prince & Smolensky, 1993), research on phonological acquisition has explored the explanatory potential of constraint theories. This study, also based on Optimality Theory, attempts to analyze the acquisition of CVVC syllable structure by Brazilian Portuguese children and addresses the issue of Local Conjunction (Smolensky, 1995, 1997) in research that deals with problems of phonological acquisition.
Constraint Programming versus Mathematical Programming
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...
Astrophysical Constraints on Dark Matter
Tao, Charling
2011-01-01
Astrophysics gives evidence for the existence of Dark Matter and puts constraints on its nature. The Cold Dark Matter model has become "standard" cosmology combined with a cosmological constant. There are indications that "Cold" Dark Matter could be "warmer" than initially discussed. This paper reviews the main information on the Cold/Warm nature of Dark Matter.
Zhang, L; Liu, W.; Langley, R.J.
2010-01-01
A class of constant modulus algorithms (CMAs) subject to a conjugate symmetric constraint is proposed for blind beamforming based on the uniform linear array structure. The constraint is derived from the beamformer with an optimum output signal-to-interference-plus-noise ratio (SINR). The effect of the additional constraint is equivalent to adding a second step to the original adaptive algorithms. The proposed approach is general and can be applied to both the traditional CMA and its all kind...
Approximating CSPs with Global Cardinality Constraints Using SDP Hierarchies
Raghavendra, Prasad
2011-01-01
This work is concerned with approximating constraint satisfaction problems (CSPs) with an additional global cardinality constraints. For example, \\maxcut is a boolean CSP where the input is a graph $G = (V,E)$ and the goal is to find a cut $S \\cup \\bar S = V$ that maximizes the numberof crossing edges, $|E(S,\\bar S)|$. The \\maxbisection problem is a variant of \\maxcut with an additional global constraint that each side of the cut has exactly half the vertices, i.e., $|S| = |V|/2$. Several other natural optimization problems like \\minbisection and approximating Graph Expansion can be formulated as CSPs with global constraints. In this work, we formulate a general approach towards approximating CSPs with global constraints using SDP hierarchies. To demonstrate the approach we present the following results: Using the Lasserre hierarchy, we present an algorithm that runs in time $O(n^{poly(1/\\epsilon)})$ that given an instance of \\maxbisection with value $1-\\epsilon$, finds a bisection with value $1-O(\\sqrt{\\epsi...
Spreading history of the Arabian Sea: Some new constraints
Chaubey, A.K.; Bhattacharya, G.C.; Murty, G.P.S.; Desa, M.
Based on a new identification of magnetic anomalies, additional constraints are provided on the two episodes of spreading history of the Arabian Sea. Commencing at A27, the older phase ended at A21 and sprading of the younger phase started shortly...
A Framework for Constraint-Programming based Configuration
Queva, Matthieu Stéphane Benoit
algorithm DnSTR is developed in order to solve the dynamic addition and retraction of table constraints at runtime. Finally, we present and evaluate a prototype implementation of ProCoLa and the configuration framework, including the integration in a development environment, tool support and interaction...
Tertiary oil recovery: potential application and constraints
Geffen, C. A.
1978-06-01
The technology of tertiary oil recovery methods is described and potential economic and environmental constraints to future commercial application are identified. Oil recoverable by tertiary techniques represents a domestic resource of between 11- and 42-billion barrels. Estimates of additional oil supplies from tertiary methods by the year 2000 range from 1 to 8 million barrels per day, depending on the price of oil and the rate of technological development. The principal constraints to large-scale application of tertiary methods at the present time include environmental, economic and technological concerns. Regulatory action associated with the Clean Air Act Amendments of 1977 currently delay the expansion of thermal recovery operations in California and may discourage future projects. The high production costs of tertiary projects also hamper process implementation. Further testing and research is necessary to develop the technology of tertiary recovery methods and prove these techniques successful on a field-wide scale. To enable tertiary oil recovery to play a significant role in augmenting domestic energy supplies, further research and development is necessary. More accurate methods of determining reservoir structure and residual oil saturations are required, as well as means for assuring the technical feasibility and success of a tertiary method in different reservoir types. Technical process limitations must also be resolved. The severity of potential environmental impacts and constraints identified in this report should be determined. These concerns include the air pollutant emissions from steam generation in thermal processes; acceptable methods of brine disposal; damage due to runoff or accidental discharge of oil-rich chemicals into surface waters; the impacts of fluid injection on deep aquifers and the prevailing geological structure; and an adequate supply of high quality fresh water.
Creativity from Constraints in Engineering Design
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...
Translating Pseudo-Boolean Constraints into CNF
Aavani, Amir
2011-01-01
A Pseudo-Boolean constraint is a linear constraint over Boolean variables. This kind of constraints has been widely used in expressing NP-complete problems. This paper introduces a new algorithm for translating Pseudo-Boolean constraints into CNF clauses. The CNF produced by the proposed encoding has small size, and we also characterize the constraints for which one can expect the SAT solvers to perform well on the produced CNF. We show that there are many constraints for which the proposed encoding has a good performance.
Thermal boundary conditions as constraints
Fosco, C D; Roditi, I
2006-01-01
We introduce the boundary conditions corresponding to the imaginary-time (Matsubara) formalism for the finite-temperature partition function in $d+1$ dimensions as {\\em constraints} in the path integral for the vacuum amplitude (the zero-temperature partition function). We implement those constraints by using Lagrange multipliers, which are static fields, two of them associated to each physical degree of freedom. After integrating out the original, physical fields, we obtain an effective representation for the partition function, depending only on the Lagrange multipliers. The resulting functional integral has the appealing property of involving only $d$-dimensional, {\\em time independent} fields, looking like a non local version of the classical partition function. We analyze the main properties of this novel representation for the partition function, developing the formalism within the context of two concrete examples: the real scalar and Dirac fields.
Water temperature constraint on Sonoluminescence
Rahvar, S
1999-01-01
It is proposed that shock wave dynamics within the gas of a small bubble explain sonoluminescence, the emission of visible radiation. As the bubble radius oscillates, shock waves develop from spherical sound waves created inside the gas bubble. As any such shock propagates toward the center, it strengthens and, upon convergence and subsequent reflection, temperature of gas inside bubble increases dramatically in such a way that it can produce plasma. Since main radiation product in exploding epoch, nonadiabatic condition for imploding shock wave cool plasma and cause exploding shock wave can not sufficiently rise temperature to produce radiation. In this work we compare cooling time for plasma by bermsstrahlung radiation with collapsing time for the imploding shock wave . We find a constraint on radius of bubble with respect to temperature of water. This constraint condition explains experimental results as to, why the cold water is fine for SL.
A Compendium of Chameleon Constraints
Burrage, Clare
2016-01-01
The chameleon model is a scalar field theory with a screening mechanism that explains how a cosmologically relevant light scalar can avoid the constraints of intra-solar-system searches for fifth-forces. The chameleon is a popular dark energy candidate and also arises in $f(R)$ theories of gravity. Whilst the chameleon is designed to avoid historical searches for fifth-forces it is not unobservable and much effort has gone into identifying the best observables and experiments to detect it. These results are not always presented for the same models or in the same language, a particular problem when comparing astrophysical and laboratory searches making it difficult to understand what regions of parameter space remain. Here we present combined constraints on the chameleon model from astrophysical and laboratory searches for the first time and identify the remaining windows of parameter space. We discuss the implications for cosmological chameleon searches and future small-scale probes.
The Viterbi Algorithm expressed in Constraint Handling Rules
Christiansen, Henning; Have, Christian Theil; Lassen, Ole Torp; Petit, Matthieu
The Viterbi algorithm is a classical example of a dynamic programming algorithm, in which pruning reduces the search space drastically, so that an otherwise exponential time complexity is reduced to linearity. The central steps of the algorithm, expansion and pruning, can be expressed in a concise...... and clear way in CHR, but additional control is needed in order to obtain the desired time complexity. It is shown how auxiliary constraints, called trigger constraints, can be applied to fine-tune the order of CHR rule applications in order to reach this goal. It is indicated how properties such as...... confluence can be useful for showing such optimized programs correct....
Low Energy Constraints and Anomalous Triple Gauge Boson Couplings
Zeppenfeld, Dieter
1993-01-01
Low energy (1-loop) constraints on anomalous triple gauge boson vertices (TGV's) are revisited and compared to the sensitivity achievable at LEP II and at future linear $e^+e^-$ colliders. The analysis is performed within the framework of an effective Lagrangian of gauge invariant dimension six operators with the gauge bosons and a single Higgs doublet field as the low energy degrees of freedom. The low energy data do not directly bound TGV's but they provide strong constraints on models which lead to anomalous gauge boson interactions in addition to other low energy effects.
Random matrix ensembles with column/row constraints: I
We analyze statistical properties of a complex system subjected to conditions which manifests through specific constraints on the column/row sum of the matrix elements of its Hermitian operators. The presence of additional constraints besides real-symmetric nature leads to new correlations among their eigenfunctions, hinders a complete delocalization of dynamics and affects the eigenvalues too. The statistical analysis of the latter indicates the presence of a new universality class analogous to that of a special type of Brownian ensemble appearing between Poisson and Gaussian orthogonal ensemble. (paper)
First-and second-class constraints in super-BRST
Using the recently obtained supersymmetric Becchi-Rouet-Stora-Tyutin transformations, the authors derive BRST- and supersymmetry-invariant equations which consist of the usual first- or second-class constraints plus ghost contributions. The ghost additions to the second-class constraints make them first-class
Ply-based Optimization of Laminated Composite Shell Structures under Manufacturing Constraints
Sørensen, Rene; Lund, Erik
2012-01-01
This work concerns a new ply-based parameterization for performing simultaneous material selection and topology optimization of fiber reinforced laminated composite structures while ensuring that a series of different manufacturing constraints are fulfilled. The material selection can either be......) with an additional constraint on the maximum allowable amount mass....
Value Constraint and Monotone circuit
Kobayashi, Koji
2012-01-01
This paper talks about that monotone circuit is P-Complete. Decision problem that include P-Complete is mapping that classify input with a similar property. Therefore equivalence relation of input value is important for computation. But monotone circuit cannot compute the equivalence relation of the value because monotone circuit can compute only monotone function. Therefore, I make the value constraint explicitly in the input and monotone circuit can compute equivalence relation. As a result...
Quantum control with spectral constraints
Pawela, Łukasz; Puchała, Zbigniew
2012-01-01
Various constraints concerning control fields can be imposed in the realistic implementations of quantum control systems. One of the most important is the restriction on the frequency spectrum of acceptable control parameters. It is important to consider the limitations of experimental equipment when trying to find appropriate control parameters. Therefore, in this paper we present a general method of obtaining a piecewise-constant controls, which are robust with respect to spectral constrain...
Managing Restaurant Tables using Constraints
Vidotto, Alfio; Brown, Kenneth N.; Beck, J. Christopher
Restaurant table management can have significant impact on both profitability and the customer experience. The core of the issue is a complex dynamic combinatorial problem. We show how to model the problem as constraint satisfaction, with extensions which generate flexible seating plans and which maintain stability when changes occur. We describe an implemented system which provides advice to users in real time. The system is currently being evaluated in a restaurant environment.
Liquidity constraints and entrepreneurial performance
Hans K. Hvide; Møen, Jarle
2007-01-01
If entrepreneurs are liquidity constrained and cannot borrow to operate on an efficient scale, those with more personal wealth should do better than those with less wealth. We investigate this hypothesis using a unique dataset from Norway. Consistent with liquidity constraints being present, we find a strong positive relationship between founder prior wealth and start-up size. The relationship between prior wealth and start-up performance, as measured by profitability on assets, increases for...
Bidding Markets with Financial Constraints
Beker, Pablo; Hernando-Veciana, Angel
2013-01-01
We develop a model of bidding markets with financial constraints a la Che and Gale (1998b) in which two firms optimally choose their budgets. First, we provide an alternative explanation for the dispersion of markups and “money left on the table” across procurement auctions. Interestingly, this explanation does not hinge on significant private information but on di?erences, both endogenous and exogenous, in the availability of financial resources. Second, we explain why the empirical analysis...
Integrating Gricean and Attentional Constraints
Passonneau, Rebecca J.
1995-01-01
This paper concerns how to generate and understand discourse anaphoric noun phrases. I present the results of an analysis of all discourse anaphoric noun phrases (N=1,233) in a corpus of ten narrative monologues, where the choice between a definite pronoun or phrasal NP conforms largely to Gricean constraints on informativeness. I discuss Dale and Reiter's [To appear] recent model and show how it can be augmented for understanding as well as generating the range of data presented here. I argu...
Intergenerational Ethics under Resource Constraints
Geir B. Asheim
2005-01-01
When evaluating long-term policies, economists usually suggest to maximize the sum of discounted utilities. On the one hand, discounted utilitarianism was given a solid axiomatic foundation by Koopmans (Econometrica 1960). On the other hand, this criterion has questionable implications when applied to economic models with resource constraints. This raises the question: What ethical conditions for intergenerational distribution should and can be imposed? I use my discussion of such conditions ...
Deepening Contractions and Collateral Constraints
Jensen, Henrik; Ravn, Søren Hove; Santoro, Emiliano
differential impact that occasionally non-binding constraints exert on the shape of expansions and contractions, we are also able to reconcile a more negatively skewed business cycle with a moderation in its volatility. Finally, our model can account for an intrinsic feature of economic downturns preceded by...... private credit build-ups: Financially driven expansions lead to deeper contractions, as compared to equally-sized non-financial expansions....
Insider Ownership and Capital Constraints
Hobdari, Bersant
2007-01-01
We analyze the impact of corporate governance structures on access to capital using a unique and rich panel data for a large and representative sample of Estonian firms over the period 1993 through 1999. We distinguish among five different governance structures and provide estimates on the impact of each of them on capital constraints. Our results indicate that: (i) separate regimes exist in investment behavior; (ii) the likelihood of being financially constrained is higher in firms that are ...
Public investment under fiscal constraints
Alessandro Missale; emanuele bacchiocchi; elisa borghi
2009-01-01
EU New Member States must comply with the Stability and Growth Pact (SGP) and the investment requirements implied by the Lisbon Agenda. However, the SGP rules may result in underinvestment or distortions in the allocation of public expenditure. This paper provides new evidence on the effects of debt sustainability and SGP fiscal constraints on government expenditure in fixed capital, education and health in OECD countries by estimating government expenditure reaction functions to public debt ...
Controlled Synchronization Under Information Constraints
Fradkov, Alexander L.; Andrievsky, Boris; Evans, Robin J.
2007-01-01
The class of controlled synchronization systems under information constraints imposed by limited information capacity of the coupling channel is analyzed. It is shown that the framework proposed in A. L. Fradkov, B. Andrievsky, R. J. Evans, Physical Review E 73, 066209 (2006) is suitable not only for observer-based synchronization but also for controlled master-slave synchronization via communication channel with limited information capacity. A simple first order coder-decoder scheme is propo...
Isocurvature Constraints on Portal Couplings
Kainulainen, Kimmo; Tenkanen, Tommi; Tuominen, Kimmo; Vaskonen, Ville
2016-01-01
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 $\\psi$ 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: $m_{\\rm DM}/{\\rm GeV}\\lesssim 0.2\\lambda_{\\rm s}^{\\scriptscriptstyle 3/8} \\left(H_*/10^{\\scriptscriptstyle 11}{\\rm GeV}\\right)^{\\scriptscriptstyle -3/2}$. This constraint is re...
Analysis of Space Tourism Constraints
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.
Cosmological constraints on neutrino oscillations
Solar, atmospheric and terrestrial neutrino experiments have provided evidence for neutrino oscillations. These neutrino anomalies were successfully explained in terms of neutrino oscillations, the dominant channels being flavour neutrino oscillations. The role of sterile neutrinos and the active-sterile subdominant channels are being explored presently. Therefore, we discuss all cosmological effects of active-sterile neutrino oscillations on the early Universe evolution, and particularly the effects on the nucleosynthesis epoch. Numerical analysis of the cosmological production of He-4, Yp in the presence of νe ↔ νs, effective after νe decoupling from the equilibrium, was provided for the full neutrino oscillations parameter range. These neutrino oscillations lead always to an overproduction of He-4. We have obtained isohelium contours corresponding to different levels of He-4 overproduction, δYp/Yp, for initial population of the sterile state in the range 0 ≤ δNs ≤ 0.5. Cosmological constraints on oscillation parameters, obtained on the base of the calculated isohelium contours and Yp observational data, are discussed. We present the constraints corresponding toδNs = 0.0 and 0.5, and helium overproduction δYp/Yp = 3%. These cosmological constraints, being more stringent than the ones provided from the neutrino experimental data, provide valuable information for the impact of sterile neutrino in the neutrino anomalies and for the neutrino physics in general. (author)
Infrared Constraint on Ultraviolet Theories
Tsai, Yuhsin [Cornell Univ., Ithaca, NY (United States)
2012-08-01
While our current paradigm of particle physics, the Standard Model (SM), has been extremely successful at explaining experiments, it is theoretically incomplete and must be embedded into a larger framework. In this thesis, we review the main motivations for theories beyond the SM (BSM) and the ways such theories can be constrained using low energy physics. The hierarchy problem, neutrino mass and the existence of dark matter (DM) are the main reasons why the SM is incomplete . Two of the most plausible theories that may solve the hierarchy problem are the Randall-Sundrum (RS) models and supersymmetry (SUSY). RS models usually suffer from strong flavor constraints, while SUSY models produce extra degrees of freedom that need to be hidden from current experiments. To show the importance of infrared (IR) physics constraints, we discuss the flavor bounds on the anarchic RS model in both the lepton and quark sectors. For SUSY models, we discuss the difficulties in obtaining a phenomenologically allowed gaugino mass, its relation to R-symmetry breaking, and how to build a model that avoids this problem. For the neutrino mass problem, we discuss the idea of generating small neutrino masses using compositeness. By requiring successful leptogenesis and the existence of warm dark matter (WDM), we can set various constraints on the hidden composite sector. Finally, to give an example of model independent bounds from collider experiments, we show how to constrain the DM–SM particle interactions using collider results with an effective coupling description.
Updating neutrino magnetic moment constraints
B.C. Cañas
2016-02-01
Full Text Available In this paper we provide an updated analysis of the neutrino magnetic moments (NMMs, discussing both the constraints on the magnitudes of the three transition moments Λi and the role of the CP violating phases present both in the mixing matrix and in the NMM matrix. The scattering of solar neutrinos off electrons in Borexino provides the most stringent restrictions, due to its robust statistics and the low energies observed, below 1 MeV. Our new limit on the effective neutrino magnetic moment which follows from the most recent Borexino data is 3.1×10−11μB at 90% C.L. This corresponds to the individual transition magnetic moment constraints: |Λ1|≤5.6×10−11μB, |Λ2|≤4.0×10−11μB, and |Λ3|≤3.1×10−11μB (90% C.L., irrespective of any complex phase. Indeed, the incoherent admixture of neutrino mass eigenstates present in the solar flux makes Borexino insensitive to the Majorana phases present in the NMM matrix. For this reason we also provide a global analysis including the case of reactor and accelerator neutrino sources, presenting the resulting constraints for different values of the relevant CP phases. Improved reactor and accelerator neutrino experiments will be needed in order to underpin the full profile of the neutrino electromagnetic properties.
Job Loss, Credit Constraints and Consumption Growth
Thomas F. Crossley; Hamish W. Low
2011-01-01
We use direct evidence on credit constraints to study their importance for household consumption growth and for welfare. We distentangle the direct effect on consumption growth of a currently binding credit constraints from the indirect effect of a potentially binding credit constraint which generates consumption risk. Our data is focused on job losers. We find that less than 5% of job losers experience a binding credit constraint, but for those that do, they experience significant welfare lo...
Breaking Weak Symmetries in Constraint Programming
Martin, Roland
2007-01-01
Constraint programming (CP) is a powerful solving paradigm that is based on inference and search control algorithms and suitable for arbitrary/various NP-hard combinatorial problems beyond linearity. The flexibility of constraints - the working machines of a CP solver - allow a wide range of problems to be solved by constraint programming solvers. Constraint propagation and search control are to two main concepts that make CP an efficient solving strategy. The former identifies infeasible reg...
Clustering trees with instance level constraints
Struyf, Jan; Dzeroski, Saso
2007-01-01
Constrained clustering investigates how to incorporate domain knowledge in the clustering process. The domain knowledge takes the form of constraints that must hold on the set of clusters. We consider instance level constraints, such as must-link and cannot-link. This type of constraints has been successfully used in popular clustering algorithms, such as k-means and hierarchical agglomerative clustering. This paper shows how clustering trees can support instance level constraints. Clustering...
Ant colony optimization and constraint programming
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
Preferences in Constraint Satisfaction and Optimization
Rossi, Francesca; University of Padova; Venable, Kristen Brent; Walsh, Toby
2009-01-01
We review constraint-based approaches to handle preferences. We start by defining the main notions of constraint programming, then give various concepts of soft constraints and show how they can be used to model quantitative preferences. We then consider how soft constraints can be adapted to handle other forms of preferences, such as bipolar, qualitative, and temporal preferences. Finally, we describe how AI techniques such as abstraction, explanation generation, machine learning, and prefer...
Procedural design of exterior lighting for buildings with complex constraints
Schwarz, Michael
2014-09-23
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.
Connectivity in Secure Wireless Sensor Networks under Transmission Constraints
Zhao, Jun; Gligor, Virgil
2015-01-01
In wireless sensor networks (WSNs), the Eschenauer-Gligor (EG) key pre-distribution scheme is a widely recognized way to secure communications. Although connectivity properties of secure WSNs with the EG scheme have been extensively investigated, few results address physical transmission constraints. These constraints reflect real-world implementations of WSNs in which two sensors have to be within a certain distance from each other to communicate. In this paper, we present zero-one laws for connectivity in WSNs employing the EG scheme under transmission constraints. These laws help specify the critical transmission ranges for connectivity. Our analytical findings are confirmed via numerical experiments. In addition to secure WSNs, our theoretical results are also applied to frequency hopping in wireless networks.
Automatic Constraint Detection for 2D Layout Regularization
Jiang, Haiyong
2015-09-18
In this paper, we address the problem of constraint detection for layout regularization. As layout we consider a set of two-dimensional elements where each element is represented by its bounding box. Layout regularization is important for digitizing plans or images, such as floor plans and facade images, and for the improvement of user created contents, such as architectural drawings and slide layouts. To regularize a layout, we aim to improve the input by detecting and subsequently enforcing alignment, size, and distance constraints between layout elements. Similar to previous work, we formulate the layout regularization as a quadratic programming problem. In addition, we propose a novel optimization algorithm to automatically detect constraints. In our results, we evaluate the proposed framework on a variety of input layouts from different applications, which demonstrates our method has superior performance to the state of the art.
Cosmological constraints on Dark Matter models for collider searches
Pree, Tristan du; Harris, Philip; Roskas, Christos
2016-01-01
Searches for Dark Matter at the LHC are commonly described in terms of simplified models with scalar, pseudo-scalar, vector and axial-vector mediators. In this work we explore the constraints imposed on such models from the observed Dark Matter relic abundance. We present these constraints over a range of mediator masses relevant for the LHC and for future, higher energy colliders. We additionally compute bounds from a photon line search for the decay of a pseudo-scalar mediator to di-photons that includes the mediator mass region near 750 GeV. Finally, we compare cosmological constraints with the reach of a possible future 100 TeV circular hadron collider, indirect, and direct detection experiments.
Space group constraints on weak indices in topological crystalline insulators
Varjas, Daniel; de Juan, Fernando; Lu, Yuan-Ming
In this work we derive constraints on weak indices of topological insulators and superconductors coming from space group symmetry. Weak indices are topological invariants of lower dimensional slices of the Brillouin zone, notable examples are the Chern numbers in class A and weak ℤ2 indices in class AII in 3D. The components of the weak indices form a momentum space vector that transforms in a simple fashion under space group symmetries, using results of momentum space crystallography we find the allowed values for each Bravais lattice. Nonsymmorphic symmetries, such as screw axes and glide planes pose additional constraints. Accounting for both of these we find that most space groups experience some restriction, to the extent that some cannot support nontrivial weak topological insulators and superconductors at all. This result puts a strong constraint on candidates in the experimental and numerical search for topological materials based on the lattice structure alone.
Revisiting constraints on uplifts to de Sitter vacua
Bizet, Nana Cabo
2016-01-01
We revisit the issue of uplifting the potential to de Sitter (dS) vacua in type IIB flux compactifications of Kachru, Kallosh, Linde and Trivedi (KKLT). We shed light on some tension between two constraints on dS vacua in type IIB string theory. One is the well-known and much-discussed constraint which leads to the no-go theorem that can in principle be evaded. The other follows from 4-dimensional Einstein's equations, which has, however, been much less discussed in connection with the former constraint. In addition to the challenges previously posed, it is suggested that the uplifting scenarios, in particular, obstruct the evasion of the no-go theorem more strongly than one might have assumed.
Exploring a type-theoretic approach to accessibility constraint modelling
Pogodalla, Sylvain
2008-01-01
The type-theoretic modelling of DRT that [degroote06] proposed features continuations for the management of the context in which a clause has to be interpreted. This approach, while keeping the standard definitions of quantifier scope, translates the rules of the accessibility constraints of discourse referents inside the semantic recipes. In this paper, we deal with additional rules for these accessibility constraints. In particular in the case of discourse referents introduced by proper nouns, that negation does not block, and in the case of rhetorical relations that structure discourses. We show how this continuation-based approach applies to those accessibility constraints and how we can consider the parallel management of various principles.
Comments on the nilpotent constraint of the goldstino superfield
Ghilencea, D M
2016-01-01
Superfield constraints were often used in the past, in particular to describe the Akulov-Volkov action of the goldstino by a superfield formulation with $L=(\\Phi^\\dagger \\Phi)_D + [(f\\Phi)_F + h.c.]$ endowed with the nilpotent constraint $\\Phi^2=0$ for the goldstino superfield ($\\Phi$). Inspired by this, such constraint is often used to define the goldstino superfield even in the presence of additional superfields, for example in models of "nilpotent inflation". In this review we show that the nilpotent property is not valid in general, under the assumption of a microscopic (ultraviolet) description of the theory with linear supermultiplets. Sometimes only weaker versions of the nilpotent relation are true such as $\\Phi^3=0$ or $\\Phi^4=0$ ($\\Phi^2\
Organizational Constraints on Corporate Public Relations Practitioners.
Ryan, Michael
1987-01-01
Catalogs various internal constraints under which many public relations practitioners work, including constraints on (1) access to management; (2) information collection; (3) dissemination of timely, accurate information; and (4) the public relations mission. Reports that most practitioners see organizational constraints as more of a problem for…
Learning and Parallelization Boost Constraint Search
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…
Pulsar constraints on screened modified gravity
We calculate the rate of energy loss from compact astrophysical objects due to a scalar field in screened modified gravity models of the chameleon, dilaton and symmetron types. The cosmological evolution of the field results in a time-variation of the scalar charge of screened objects, implying the emission of scalar radiation. Focusing on binary objects, this leads to an additional decay in the orbital period complementing that due to the emission of gravitational waves. Using the Hulse–Taylor binary pulsar, the double pulsar PSR J0737–3039 and the pulsar-white dwarf system PSR J1738 + 033, we find a new observational bound on the time variation of the scalar charge of the Earth in the Milky Way. We then translate this into a new bound on the range of the scalar interaction in the Milky Way. Ultimately, we find that pulsar tests are not competitive with current observational constraints. (paper)
Global constraints on heavy neutrino mixing
Fernandez-Martinez, Enrique; Lopez-Pavon, Jacobo
2016-01-01
We derive general constraints on the mixing of heavy Seesaw neutrinos with the SM fields from a global fit to present flavour and electroweak precision data. We explore and compare both a completely general scenario, where the heavy neutrinos are integrated out without any further assumption, and the more constrained case were only 3 additional heavy states are considered. The latter assumption implies non-trivial correlations in order to reproduce the correct neutrino masses and mixings as observed by oscillation data and thus some qualitative differences can be found with the more general scenario. The relevant processes analyzed in the global fit include searches for Lepton Flavour Violating (LFV) decays, probes of the universality of weak interactions, CKM unitarity bounds and electroweak precision data. In particular, a comparative and detailed study of the present and future sensitivity of the different LFV experiments is performed. We find a mild $1-2\\sigma$ preference for non-zero heavy neutrino mixin...
Minimum weight design of helicopter rotor blades with frequency constraints
Chattopadhyay, Aditi; Walsh, Joanne L.
1989-01-01
The minimum weight design of helicopter rotor blades subject to constraints on fundamental coupled flap-lag natural frequencies has been studied in this paper. A constraint has also been imposed on the minimum value of the blade autorotational inertia to ensure that the blade has sufficient inertia to autorotate in case of an engine failure. The program CAMRAD has been used for the blade modal analysis and the program CONMIN has been used for the optimization. In addition, a linear approximation analysis involving Taylor series expansion has been used to reduce the analysis effort. The procedure contains a sensitivity analysis which consists of analytical derivatives of the objective function and the autorotational inertia constraint and central finite difference derivatives of the frequency constraints. Optimum designs have been obtained for blades in vacuum with both rectangular and tapered box beam structures. Design variables include taper ratio, nonstructural segment weights and box beam dimensions. The paper shows that even when starting with an acceptable baseline design, a significant amount of weight reduction is possible while satisfying all the constraints for blades with rectangular and tapered box beams.
A Variable Depth Search Algorithm for Binary Constraint Satisfaction Problems
N. Bouhmala
2015-01-01
Full Text Available The constraint satisfaction problem (CSP is a popular used paradigm to model a wide spectrum of optimization problems in artificial intelligence. This paper presents a fast metaheuristic for solving binary constraint satisfaction problems. The method can be classified as a variable depth search metaheuristic combining a greedy local search using a self-adaptive weighting strategy on the constraint weights. Several metaheuristics have been developed in the past using various penalty weight mechanisms on the constraints. What distinguishes the proposed metaheuristic from those developed in the past is the update of k variables during each iteration when moving from one assignment of values to another. The benchmark is based on hard random constraint satisfaction problems enjoying several features that make them of a great theoretical and practical interest. The results show that the proposed metaheuristic is capable of solving hard unsolved problems that still remain a challenge for both complete and incomplete methods. In addition, the proposed metaheuristic is remarkably faster than all existing solvers when tested on previously solved instances. Finally, its distinctive feature contrary to other metaheuristics is the absence of parameter tuning making it highly suitable in practical scenarios.
On Factorization Constraints for Branes in the H3+ Model
Adorf, Hendrik; Flohr, Michael
We comment on the brane solutions for the boundary H3+ model that have been proposed so far and point out that they should be distinguished according to the patterns regular/irregular and discrete/continuous. In the literature, mostly irregular branes have been studied, while results on the regular ones are rare. For all types of branes, there are questions about how a second factorization constraint in the form of a b-2/2-shift equation can be derived. Here, we assume analyticity of the boundary two-point function, which means that the Cardy-Lewellen constraints remain unweakened. This enables us to derive unambiguously the desired b-2/2-shift equations. They serve as important additional consistency conditions. For some regular branes, we also derive 1/2-shift equations that were not known previously. Case by case, we discuss possible solutions to the enlarged system of constraints. We find that the well-known irregular continuous AdS2 branes are consistent with our new factorization constraint. Furthermore, we establish the existence of a new type of brane: the shift equations in a certain regular discrete case possess a nontrivial solution that we write down explicitly. All other types are found to be inconsistent when using our second constraint. We discuss these results in view of the Hosomichi-Ribault proposal and some of our earlier results on the derivation of b-2/2-shift equations.
Conjure Revisited: Towards Automated Constraint Modelling
Akgun, Ozgur; Hnich, Brahim; Jefferson, Chris; Miguel, Ian
2011-01-01
Automating the constraint modelling process is one of the key challenges facing the constraints field, and one of the principal obstacles preventing widespread adoption of constraint solving. This paper focuses on the refinement-based approach to automated modelling, where a user specifies a problem in an abstract constraint specification language and it is then automatically refined into a constraint model. In particular, we revisit the Conjure system that first appeared in prototype form in 2005 and present a new implementation with a much greater coverage of the specification language Essence.
Constraint Specialisation in Horn Clause Verification
Kafle, Bishoksan; Gallagher, John Patrick
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...
A Maximal Tractable Class of Soft Constraints
Cohen, D; Jeavons, P; Krokhin, A; 10.1613/jair.1400
2011-01-01
Many researchers in artificial intelligence are beginning to explore the use of soft constraints to express a set of (possibly conflicting) problem requirements. A soft constraint is a function defined on a collection of variables which associates some measure of desirability with each possible combination of values for those variables. However, the crucial question of the computational complexity of finding the optimal solution to a collection of soft constraints has so far received very little attention. In this paper we identify a class of soft binary constraints for which the problem of finding the optimal solution is tractable. In other words, we show that for any given set of such constraints, there exists a polynomial time algorithm to determine the assignment having the best overall combined measure of desirability. This tractable class includes many commonly-occurring soft constraints, such as 'as near as possible' or 'as soon as possible after', as well as crisp constraints such as 'greater than'. F...
Percolation of spatially constraint networks
Li, Daqing; Li, Guanliang; Kosmidis, Kosmas; Stanley, H. E.; Bunde, Armin; Havlin, Shlomo
2011-03-01
We study how spatial constraints are reflected in the percolation properties of networks embedded in one-dimensional chains and two-dimensional lattices. We assume long-range connections between sites on the lattice where two sites at distance r are chosen to be linked with probability p(r)~r-δ. Similar distributions have been found in spatially embedded real networks such as social and airline networks. We find that for networks embedded in two dimensions, with 24 it belongs to the universality class of percolation in regular lattices. For networks embedded in one dimension, we find that, for δ2 there is no percolation transition as in regular linear chains.
Beyond the Constraints of Reality
Hansen, Kim Toft
horror (the affection on the body) and lastly the emotion of belief (“the idea that God exists”). In that sense, the poetics of horror can as well draw heavily upon the idea of mimetic aspects of fiction and, basically and correspondingly, Lucio Fulci’s cult film The Beyond is a core example of how...... horror draws upon another implication in the word ‘cult’, namely the religious cult. Both religion and horror deals with going beyond the constraints of reality....
Ordinal Classification with Monotonicity Constraints
Horváth, T.; Vojtáš, Peter
Berlin: Springer, 2006 - (Perner, P.), s. 217-225. (Lecture Notes in Artificial Intelligence. 4065). ISBN 978-3-540-36036-0. [ICDM 2006. Industrial Conference on Data Mining /6./. Leipzig (DE), 14.07.2006-15.07.2006] R&D Projects: GA AV ČR 1ET100300517 Grant ostatní: VEGA(SK) 1/3129/06 Institutional research plan: CEZ:AV0Z10300504 Keywords : monotone * monotonicity constraints * classification * ordinal data Subject RIV: IN - Informatics, Computer Science
Chance-Constrained Guidance With Non-Convex Constraints
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
Design for Additive Manufacturing
Bertran Comellas, Martí
2012-01-01
This Thesis, Design for Additive Manufacturing, has been mainly focused on the design process and the considerations to be taken into account when designing parts for Additive Manufacturing. It starts with an introduction to Additive Manufacturing, the different technologies and processes are described to let the readers understand their operating principle, materials used and their strengths and weaknesses. The applications of Additive manufacturing are also explained in the introductory ...
Cognitive constraints on motor imagery.
Dahm, Stephan F; Rieger, Martina
2016-03-01
Executed bimanual movements are prepared slower when moving to symbolically different than when moving to symbolically same targets and when targets are mapped to target locations in a left/right fashion than when they are mapped in an inner/outer fashion [Weigelt et al. (Psychol Res 71:238-447, 2007)]. We investigated whether these cognitive bimanual coordination constraints are observable in motor imagery. Participants performed fast bimanual reaching movements from start to target buttons. Symbolic target similarity and mapping were manipulated. Participants performed four action conditions: one execution and three imagination conditions. In the latter they indicated starting, ending, or starting and ending of the movement. We measured movement preparation (RT), movement execution (MT) and the combined duration of movement preparation and execution (RTMT). In all action conditions RTs and MTs were longer in movements towards different targets than in movements towards same targets. Further, RTMTs were longer when targets were mapped to target locations in a left/right fashion than when they were mapped in an inner/outer fashion, again in all action conditions. RTMTs in imagination and execution were similar, apart from the imagination condition in which participants indicated the start and the end of the movement. Here MTs, but not RTs, were longer than in the execution condition. In conclusion, cognitive coordination constraints are present in the motor imagery of fast (motor imagery. PMID:25758054
OPTIMIZATION WITH LINEAR COMPLEMENTARITY CONSTRAINTS
Joaquim Júdice
2014-12-01
Full Text Available A Mathematical Program with Linear Complementarity Constraints (MPLCC is an optimization problem where a continuously differentiable function is minimized on a set defined by linear constraints and complementarity conditions on pairs of complementary variables. This problem finds many applications in several areas of science, engineering and economics and is also an important tool for the solution of some NP-hard structured and nonconvex optimization problems, such as bilevel, bilinear and nonconvex quadratic programs and the eigenvalue complementarity problem. In this paper some of the most relevant applications of the MPLCC and formulations of nonconvex optimization problems as MPLCCs are first presented. Algorithms for computing a feasible solution, a stationary point and a global minimum for the MPLCC are next discussed. The most important nonlinear programming methods, complementarity algorithms, enumerative techniques and 0 - 1 integer programming approaches for the MPLCC are reviewed. Some comments about the computational performance of these algorithms and a few topics for future research are also included in this survey.
Testing multiple coordination constraints with a novel bimanual visuomotor task.
Helene M Sisti
Full Text Available The acquisition of a new bimanual skill depends on several motor coordination constraints. To date, coordination constraints have often been tested relatively independently of one another, particularly with respect to isofrequency and multifrequency rhythms. Here, we used a new paradigm to test the interaction of multiple coordination constraints. Coordination constraints that were tested included temporal complexity, directionality, muscle grouping, and hand dominance. Twenty-two healthy young adults performed a bimanual dial rotation task that required left and right hand coordination to track a moving target on a computer monitor. Two groups were compared, either with or without four days of practice with augmented visual feedback. Four directional patterns were tested such that both hands moved either rightward (clockwise, leftward (counterclockwise, inward or outward relative to each other. Seven frequency ratios (3∶1, 2∶1, 3∶2, 1∶1, 2∶3. 1∶2, 1∶3 between the left and right hand were introduced. As expected, isofrequency patterns (1∶1 were performed more successfully than multifrequency patterns (non 1∶1. In addition, performance was more accurate when participants were required to move faster with the dominant right hand (1∶3, 1∶2 and 2∶3 than with the non-dominant left hand (3∶1, 2∶1, 3∶2. Interestingly, performance deteriorated as the relative angular velocity between the two hands increased, regardless of whether the required frequency ratio was an integer or non-integer. This contrasted with previous finger tapping research where the integer ratios generally led to less error than the non-integer ratios. We suggest that this is due to the different movement topologies that are required of each paradigm. Overall, we found that this visuomotor task was useful for testing the interaction of multiple coordination constraints as well as the release from these constraints with practice in the presence of
Additives in yoghurt production
Milna Tudor
2008-02-01
Full Text Available In yoghurt production, mainly because of sensory characteristics, different types of additives are used. Each group, and also each substance from the same group has different characteristics and properties. For that reason, for improvement of yoghurt sensory characteristics apart from addition selection, the quantity of the additive is very important. The same substance added in optimal amount improves yoghurt sensory attributes, but too small or too big addition can reduce yoghurt sensory attributes. In this paper, characteristics and properties of mostly used additives in yoghurt production are described; skimmed milk powder, whey powder, concentrated whey powder, sugars and artificial sweeteners, fruits, stabilizers, casein powder, inulin and vitamins. Also the impact of each additive on sensory and physical properties of yoghurt, syneresis and viscosity, are described, depending on used amount added in yoghurt production.
Langlais, R
1996-01-01
With the adoption of the European Parliament and Council Directives on sweeteners, colours and miscellaneous additives the Commission is now embarking on the project of coordinating the activities of the European Union Member States in the collection of the data that are to make up the report on food additive intake requested by the European Parliament. This presentation looks at the inventory of available sources on additive use levels and concludes that for the time being national legislation is still the best source of information considering that the directives have yet to be transposed into national legislation. Furthermore, this presentation covers the correlation of the food categories as found in the additives directives with those used by national consumption surveys and finds that in a number of instances this correlation still leaves a lot to be desired. The intake of additives via food ingestion and the intake of substances which are chemically identical to additives but which occur naturally in fruits and vegetables is found in a number of cases to be higher than the intake of additives added during the manufacture of foodstuffs. While the difficulties are recognized in contributing to the compilation of food additive intake data, industry as a whole, i.e. the food manufacturing and food additive manufacturing industries, are confident that in a concerted effort, use data on food additives by industry can be made available. Lastly, the paper points out that with the transportation of the additives directives into national legislation and the time by which the food industry will be able to make use of the new food legislative environment several years will still go by; food additives use data by the food industry will thus have to be reviewed at the beginning of the next century. PMID:8792135
无
2006-01-01
C-H bond can undergo vicarious Michael addition reaction (VMA) with doubleactivated double bond in the absence of strong base and catalyst under mild conditions.Intramolecular H-bonding, electron-withdrawing inductive effect, and steric hindrance at aposition of nucleophile facilitates C-H addition over N-H addition. By using VMA, high branching multiplicity, novel branching pattern, controllable density and distribution of functional groups can be envisioned for novel dendrimer synthesis.
Wire + Arc Additive Manufacturing
Williams, Stewart W.; Martina, Filomeno; Addison, Adrian C.; Ding, Jialuo; Pardal, Goncalo; Colegrove, Paul A.
2016-01-01
Depositing large components (>10 kg) in titanium, aluminium, steel and other metals is possible using Wire + Arc Additive Manufacturing. This technology adopts arc welding tools and wire as feedstock for additive manufacturing purposes. High deposition rates, low material and equipment costs, and good structural integrity make Wire+Arc Additive Manufacturing a suitable candidate for replacing the current method of manufacturing from solid billets or large forgings, especially with regards to ...
Constraints on holographic cosmologies from strong lensing systems
We use strongly gravitationally lensed (SGL) systems to put additional constraints on a set of holographic dark energy models. Data available in the literature (redshift and velocity dispersion) is used to obtain the Einstein radius and compare it with model predictions. We found that the ΛCDM is the best fit to the data. Although a preliminary statistical analysis seems to indicate that two of the holographic models studied show interesting agreement with observations, a stringent test lead us to the result that neither of the holographic models are competitive with the ΛCDM. These results highlight the importance of Strong Lensing measurements to provide additional observational constraints to alternative cosmological models, which are necessary to shed some light into the dark universe
Constraints On Holographic Cosmological Models From Gamma Ray Bursts
Rivera, Alexander Bonilla
2016-01-01
We use Gamma Ray Bursts (GRBs) data to put additional constraints on a set of holographic dark energy models. GRBs are the most energetic events in the Universe and provide a complementary probe of dark energy by allowing the measurement of cosmic expansion history that extends to redshifts greater than 6 and they are complementary to SNIa test. We found that the LCDM model is the best fit to the data, although a preliminary statistical analysis seems to indicate that the holographic models studied show interesting agreement with observations, except Ricci Scale CPL model. These results show the importance of GRBs measurements to provide additional observational constraints to alternative cosmological models, which are necessary to clarify the way in the paradigm of dark energy or potential alternatives.
Constraint Embedding for Multibody System Dynamics
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.
Causality Constraints in Conformal Field Theory
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...
Causality constraints in conformal field theory
Hartman, Thomas; Jain, Sachin; Kundu, Sandipan
2016-05-01
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 spinning operators.
Causality Constraints in Conformal Field Theory
Hartman, Thomas; Kundu, Sandipan
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 $(\\partial\\phi)^4$ 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 o...
Integrating Gricean and Attentional Constraints
Passonneau, R J
1995-01-01
This paper concerns how to generate and understand discourse anaphoric noun phrases. I present the results of an analysis of all discourse anaphoric noun phrases (N=1,233) in a corpus of ten narrative monologues, where the choice between a definite pronoun or phrasal NP conforms largely to Gricean constraints on informativeness. I discuss Dale and Reiter's [To appear] recent model and show how it can be augmented for understanding as well as generating the range of data presented here. I argue that integrating centering [Grosz et al., 1983] [Kameyama, 1985] with this model can be applied uniformly to discourse anaphoric pronouns and phrasal NPs. I conclude with a hypothesis for addressing the interaction between local and global discourse processing.
Meditations on Quantified Constraint Satisfaction
Chen, Hubie
2012-01-01
The quantified constraint satisfaction problem (QCSP) is the problem of deciding, given a structure and a first-order prenex sentence whose quantifier-free part is the conjunction of atoms, whether or not the sentence holds on the structure. One obtains a family of problems by defining, for each structure B, the problem QCSP(B) to be the QCSP where the structure is fixed to be B. In this article, we offer a viewpoint on the research program of understanding the complexity of the problems QCSP(B) on finite structures. In particular, we propose and discuss a group of conjectures; throughout, we attempt to place the conjectures in relation to existing results and to emphasize open issues and potential research directions.
Default and Credit Constraint in General equilibrium
Xavier Ragot; François Le Grand
2011-01-01
We study an economy where infinitely living agents face uninsurable shocks and are allowed default on their debt. After having defaulted, agents are excluded from the economy. We present a equilibrium definition allowing for both credit constraints and default inequilibrium. Indeed, existing theories introduce either default of credit constraint in general equilibrium, but never both. We prove that the optimal allocation includes both credit constraints and default, while the market allocatio...
Extended Time Constraints for Generalized Sequential Patterns
Fiot, Céline
2006-01-01
Version étendue de l'article soumis à la revue IJWET Mining temporal knowledge has many applications. Such knowledge can be all the more interesting as some time constraints between events can be pushed into during theminingtask. As well in data mining as in machine learning, some methods have been proposedto extract and manage such knowledge using temporal constraints. In particular some work has been done to mine generalized sequential patterns. However such constraints are often too cri...
Integration of Declarative and Constraint Programming
Hofstedt, Petra; Pepper, Peter
2005-01-01
Combining a set of existing constraint solvers into an integrated system of cooperating solvers is a useful and economic principle to solve hybrid constraint problems. In this paper we show that this approach can also be used to integrate different language paradigms into a unified framework. Furthermore, we study the syntactic, semantic and operational impacts of this idea for the amalgamation of declarative and constraint programming.
Endogenous Liquidity Constraints in a Dynamic Contest
Martin Grossmann
2011-01-01
In this article, I analyze the effects of future liquidity constraints on the investment behavior of two contestants with asymmetric prize valuations in a dynamic contest model. Contestants compete in two consecutive Tullock contests in order to win a contest prize in each period. The loser of the first-period contest can be liquidity constraint in the second period. The model reveals the following four main results: (i) Future liquidity constraints marginally affect today's intensity of comp...
Geographic versus industry diversification: constraints matter
Paul EHLING; Ramos, Sofia Brito
2005-01-01
This research addresses whether geographic diversification provides benefits over industry diversification. In the absence of constraints, no empirical evidence is found to support the argument that country diversification is superior. With short-selling constraints, however, the geographic tangency portfolio is not attainable by industry portfolios. Results with upper and lower constraints on portfolio weights as well as an out-of-sample analysis show that geographic diversification almost c...
On the general constraints in single qubit quantum process tomography
Bhandari, Ramesh; Peters, Nicholas A.
2016-01-01
We briefly review single-qubit quantum process tomography for trace-preserving and nontrace-preserving processes, and derive explicit forms of the general constraints for fitting experimental data. These forms provide additional insight into the structure of the process matrix. We illustrate this with several examples, including a discussion of qubit leakage error models and the intuition which can be gained from their process matrices. PMID:27188691
On the general constraints in single qubit quantum process tomography
Bhandari, Ramesh; Peters, Nicholas A.
2016-01-01
We briefly review single-qubit quantum process tomography for trace-preserving and nontrace-preserving processes, and derive explicit forms of the general constraints for fitting experimental data. These new forms provide additional insight into the structure of the process matrix. We illustrate their utility with several examples, including a discussion of qubit leakage error models and the intuition which can be gained from their process matrices.
Toward an automaton Constraint for Local Search
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].
Comments on the nilpotent constraint of the goldstino superfield
Ghilencea, D. M.
2016-04-01
Superfield constraints were often used in the past, in particular, to describe the Akulov-Volkov action of the goldstino by a superfield formulation with L = (Φ†Φ) D + [(fΦ)F + h.c.] endowed with the nilpotent constraint Φ2 = 0 for the goldstino superfield (Φ). Inspired by this, such constraint is often used to define the goldstino superfield even in the presence of additional superfields, for example, in models of “nilpotent inflation”. In this review, we show that the nilpotent property is not valid, in general, under the assumption of a microscopic (ultraviolet (UV)) description of the theory with linear supermultiplets. Sometimes only weaker versions of the nilpotent relation are true such as Φ3 = 0 or Φ4 = 0 (Φ2≠0) in the infrared (far below the UV scale) under the further requirement of decoupling all additional scalars (coupling to sgoldstino), something not always possible (e.g. if light scalars exist). In such cases, the weaker nilpotent property is not specific to the goldstino superfield anymore. We review the restrictions for the Kahler curvature tensor and superpotential W under which Φ2 = 0 remains true in infrared, assuming linear supermultiplets in the microscopic description. One can reverse the arguments to demand that the nilpotent condition, initially an infrared property, be extended even in the presence of additional superfields, but this may question the nature of supersymmetry breaking or the existence of a perturbative UV description with linear supermultiplets.
Technology for planning and scheduling under complex constraints
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.
On Factorization Constraints for Branes in the H3+ Model
Adorf, Hendrik
2008-01-01
We comment on the brane solutions for the boundary H3+ model that have been proposed so far and point out that they should be distinguished according to the patterns regular/irregular and discrete/continuous. In the literature, mostly irregular branes have been studied, while results on the regular ones are rare. For all types of branes, there are questions about how a second factorization constraint in the form of a b^{-2}/2-shift equation can be derived. Here, we assume analyticity of the boundary two point function, which means that the Cardy-Lewellen constraints remain unweakened. This enables us to derive unambiguously the desired b^{-2}/2-shift equations. They serve as important additional consistency conditions. For some regular branes, we also derive 1/2-shift equations that were not known previously. Case by case, we discuss possible solutions to the enlarged system of constraints. We find that the well-known irregular continuous AdS_2 branes are consistent with our new factorization constraint. Furt...
Additive and polynomial representations
Krantz, David H; Suppes, Patrick
1971-01-01
Additive and Polynomial Representations deals with major representation theorems in which the qualitative structure is reflected as some polynomial function of one or more numerical functions defined on the basic entities. Examples are additive expressions of a single measure (such as the probability of disjoint events being the sum of their probabilities), and additive expressions of two measures (such as the logarithm of momentum being the sum of log mass and log velocity terms). The book describes the three basic procedures of fundamental measurement as the mathematical pivot, as the utiliz
Food Additives and Hyperkinesis
Wender, Ester H.
1977-01-01
The hypothesis that food additives are causally associated with hyperkinesis and learning disabilities in children is reviewed, and available data are summarized. Available from: American Medical Association 535 North Dearborn Street Chicago, Illinois 60610. (JG)
Coghetto Roland
2015-06-01
Full Text Available We translate the articles covering group theory already available in the Mizar Mathematical Library from multiplicative into additive notation. We adapt the works of Wojciech A. Trybulec [41, 42, 43] and Artur Korniłowicz [25].
Ravikumar, Pradeep; Lafferty, John; Liu, Han; Wasserman, Larry
2007-01-01
We present a new class of methods for high-dimensional nonparametric regression and classification called sparse additive models (SpAM). Our methods combine ideas from sparse linear modeling and additive nonparametric regression. We derive an algorithm for fitting the models that is practical and effective even when the number of covariates is larger than the sample size. SpAM is closely related to the COSSO model of Lin and Zhang (2006), but decouples smoothing and sparsity, enabling the use...
Additively Manufactured Propulsion System
Dushku, Matthew; Mueller, Paul
2012-01-01
New high-performance, carbon-fiber reinforced polymer material allows additive manufacturing to produce pressure vessels capable of high pressures (thousands of pounds per square inch). This advancement in turn allows integral hybrid propulsion which is revolutionary for both CubeSats and additively-manufactured spacecraft. Hybrid propulsion offers simplicity as compared to bipropellant liquid propulsion, significantly better safety compared to solid or monopropellant hydrazine propulsion, an...
Virasoro constraint for Nekrasov instanton partition function
Kanno, Shoichi; Zhang, Hong
2012-01-01
We show that Nekrasov instanton partition function for SU(N) gauge theories satisfies recursion relations in the form of U(1)+Virasoro constraints when {\\beta} = 1. The constraints give a direct support for AGT conjecture for general quiver gauge theories.
Optimal Portfolio Choice with Wash Sale Constraints
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 is to a...
Review of Minimal Flavor Constraints for Technicolor
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...
A Temporal Concurrent Constraint Programming Calculus
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...
Supernova constraints on neutrino mass and mixing
Srubabati Goswami
2000-01-01
In this article I review the constraints on neutrino mass and mixing coming from type-II supernovae. The bounds obtained on these parameters from shock reheating, -process nucleosynthesis and from SN1987A are discussed. Given the current constraints on neutrino mass and mixing the effect of oscillations of neutrinos from a nearby supernova explosion in future detectors will also be discussed.
Constraint Satisfaction with Counting Quantifiers
Madelaine, Florent; Stacho, Juraj
2011-01-01
We initiate the study of constraint satisfaction problems (CSPs) in the presence of counting quantifiers, which may be seen as variants of CSPs in the mould of quantified CSPs (QCSPs). We show that a single counting quantifier strictly between exists^1:=exists and exists^n:=forall (the domain being of size n) already affords the maximal possible complexity of QCSPs (which have both exists and forall), being Pspace-complete for a suitably chosen template. Next, we focus on the complexity of subsets of counting quantifiers on clique and cycle templates. For cycles we give a full trichotomy -- all such problems are in L, NP-complete or Pspace-complete. For cliques we come close to a similar trichotomy, but one case remains outstanding. Afterwards, we consider the generalisation of CSPs in which we augment the extant quantifier exists^1:=exists with the quantifier exists^j (j not 1). Such a CSP is already NP-hard on non-bipartite graph templates. We explore the situation of this generalised CSP on bipartite templ...
Volcanological constraints of Archaean tectonics
Thurston, P. C.; Ayres, L. D.
1986-01-01
Volcanological and trace element geochemical data can be integrated to place some constraints upon the size, character and evolutionary history of Archean volcanic plumbing, and hence indirectly, Archean tectonics. The earliest volcanism in any greenhouse belt is almost universally tholeitic basalt. Archean mafic magma chambers were usually the site of low pressure fractionation of olivine, plagioclase and later Cpx + or - an oxide phase during evolution of tholeitic liquids. Several models suggest basalt becoming more contaminated by sial with time. Data in the Uchi Subprovince shows early felsic volcanics to have fractionated REE patterns followed by flat REE pattern rhyolites. This is interpreted as initial felsic liquids produced by melting of a garnetiferous mafic source followed by large scale melting of LIL-rich sial. Rare andesites in the Uchi Subprovince are produced by basalt fractionation, direct mantle melts and mixing of basaltic and tonalitic liquids. Composite dikes in the Abitibi Subprovince have a basaltic edge with a chill margin, a rhyolitic interior with no basalt-rhyolite chill margin and partially melted sialic inclusions. Ignimbrites in the Uchi and Abitibi Subprovinces have mafic pumice toward the top. Integration of these data suggest initial mantle-derived basaltic liquids pond in a sialic crust, fractionate and melt sial. The inirial melts low in heavy REE are melts of mafic material, subsequently melting of adjacent sial produces a chamber with a felsic upper part underlain by mafic magma.
Controlled synchronization under information constraints
Fradkov, Alexander L.; Andrievsky, Boris; Evans, Robin J.
2008-09-01
A class of controlled synchronization systems under information constraints imposed by limited information capacity of the coupling channel is analyzed. It is shown that the framework proposed by Fradkov , [Phys. Rev. E 73, 066209 (2006)] is suitable not only for observer-based synchronization but also for controlled master-slave synchronization via a communication channel with limited information capacity. A simple first-order coder-decoder scheme is proposed and a theoretical analysis for multidimensional master-slave systems represented in the Lurie form (linear part plus nonlinearity depending only on measurable outputs) is provided. An output feedback control law is proposed based on the passification method. It is shown that for systems with passifiable linear part (satisfying the hyperminimum phase condition) the upper bound of the limiting synchronization error is proportional to the upper bound of the transmission error. As a consequence, both upper and lower bounds of the limiting synchronization error are proportional to the maximum rate of the coupling signal and inversely proportional to the information transmission rate (channel capacity). The results are applied to controlled synchronization of two chaotic Chua systems coupled via a controller and a channel with limited capacity. It is shown by computer simulation that, unlike for the case of observer-based synchronization, the hyperminimum phase property cannot be violated for controlled synchronization.
Constraints on Sterile Neutrino Dark Matter
Abazajian, Kevork N; Abazajian, Kevork; Koushiappas, Savvas M.
2006-01-01
We present a comprehensive analysis of constraints on the sterile neutrino as a dark matter candidate. The minimal production scenario with a standard thermal history and negligible cosmological lepton number is in conflict with conservative radiative decay constraints from the cosmic X-ray background in combination with stringent small-scale structure limits from the Lyman-alpha forest. We show that entropy release through massive particle decay after production does not alleviate these constraints. We further show that radiative decay constraints from local group dwarf galaxies are subject to large uncertainties in the dark matter density profile of these systems. Within the strongest set of constraints, resonant production of cold sterile neutrino dark matter in non-zero lepton number cosmologies remains allowed.
Chi-Jen Lin
2015-11-01
Full Text Available This study constructs a practical fuzzy three-dimensional axial assignment model, and proposes two efficient algorithms to solve the model. In our case, the model is applied to team performance management in a company to promote the performance of all members in a team. Two algorithms, namely the index-based branch and bound (B&B algorithm and the f-g trade-off algorithm, which is a hybrid of the trade-off and B&B concepts, are proposed. A numerical example is presented to illustrate these two algorithms. The computational results show that the proposed algorithms are sufficiently efficient and accurate. Two special cases are also discussed.
Additive Manufacturing Infrared Inspection
Gaddy, Darrell
2014-01-01
Additive manufacturing is a rapid prototyping technology that allows parts to be built in a series of thin layers from plastic, ceramics, and metallics. Metallic additive manufacturing is an emerging form of rapid prototyping that allows complex structures to be built using various metallic powders. Significant time and cost savings have also been observed using the metallic additive manufacturing compared with traditional techniques. Development of the metallic additive manufacturing technology has advanced significantly over the last decade, although many of the techniques to inspect parts made from these processes have not advanced significantly or have limitations. Several external geometry inspection techniques exist such as Coordinate Measurement Machines (CMM), Laser Scanners, Structured Light Scanning Systems, or even traditional calipers and gages. All of the aforementioned techniques are limited to external geometry and contours or must use a contact probe to inspect limited internal dimensions. This presentation will document the development of a process for real-time dimensional inspection technique and digital quality record of the additive manufacturing process using Infrared camera imaging and processing techniques.
Flavor Constraints on Split Fermion Models
Lillie, Benjamin Huntington; Lillie, Ben; Hewett, JoAnne
2003-01-01
We examine the contributions to rare processes that arise in models where the Standard Model fermions are localized at distinct points in compact extra dimensions. Tree-level flavor changing neutral current interactions for the Kaluza-Klein (KK) gauge field excitations are induced in such models, and hence strong constraints are thought to exist on the size of the additional dimensions. We find a general parameterization of the model which does not depend on any specific fermion geography and show that typical values of the parameters can reproduce the fermion hierarchy pattern. Using this parameterization, we reexamine the contributions to neutral meson mixing, rare meson decays, and single top-quark production in $e^+e^-$ collisions. We find that is it possible to evade the stringent bounds for natural regions of the parameters, while retaining finite separations between the fermion fields and without introducing a new hierarchy. The resulting limits on the size of the compact dimension can be as low as TeV...
Magneto-reheating constraints from curvature perturbations
As additional perturbative degrees of freedom, it is known that magnetic fields of inflationary origin can source curvature perturbations on super-Hubble scales. By requiring the magnetic generated curvature to remain smaller than its inflationary adiabatic counterpart during inflation and reheating, we derive new constraints on the maximal field value today, the reheating energy scale and its equation of state parameter. These bounds end up being stronger by a few order of magnitude than those associated with a possible backreaction of the magnetic field onto the background. Our results are readily applicable to any slow-roll single field inflationary models and any magnetic field having its energy density scaling as aγ during inflation. As an illustrative example, massive inflation is found to remain compatible with a magnetic field today B0 = 5 × 10−15 G for some values of γ only if a matter dominated reheating takes place at energies larger than 105 GeV. Conversely, assuming γ = −1, massive inflation followed by a matter dominated reheating cannot explain large scale magnetic fields larger than 10−20 G today
Magneto-reheating constraints from curvature perturbations
Ringeval, Christophe [Centre for Cosmology, Particle Physics and Phenomenology, Institute of Mathematics and Physics, Louvain University, 2 Chemin du Cyclotron, 1348 Louvain-la-Neuve (Belgium); Suyama, Teruaki; Yokoyama, Jun' ichi, E-mail: christophe.ringeval@uclouvain.be, E-mail: suyama@resceu.s.u-tokyo.ac.jp, E-mail: yokoyama@resceu.s.u-tokyo.ac.jp [Research Center for the Early Universe (RESCEU), Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan)
2013-09-01
As additional perturbative degrees of freedom, it is known that magnetic fields of inflationary origin can source curvature perturbations on super-Hubble scales. By requiring the magnetic generated curvature to remain smaller than its inflationary adiabatic counterpart during inflation and reheating, we derive new constraints on the maximal field value today, the reheating energy scale and its equation of state parameter. These bounds end up being stronger by a few order of magnitude than those associated with a possible backreaction of the magnetic field onto the background. Our results are readily applicable to any slow-roll single field inflationary models and any magnetic field having its energy density scaling as a{sup γ} during inflation. As an illustrative example, massive inflation is found to remain compatible with a magnetic field today B{sub 0} = 5 × 10{sup −15} G for some values of γ only if a matter dominated reheating takes place at energies larger than 10{sup 5} GeV. Conversely, assuming γ = −1, massive inflation followed by a matter dominated reheating cannot explain large scale magnetic fields larger than 10{sup −20} G today.
Flavor Constraints on Split Fermion Models
We examine the contributions to rare processes that arise in models where the Standard Model fermions are localized at distinct points in compact extra dimensions. Tree-level flavor changing neutral current interactions for the Kaluza-Klein (KK) gauge field excitations are induced in such models, and hence strong constraints are thought to exist on the size of the additional dimensions. We find a general parameterization of the model which does not depend on any specific fermion geography and show that typical values of the parameters can reproduce the fermion hierarchy pattern. Using this parameterization, we reexamine the contributions to neutral meson mixing, rare meson decays, and single top-quark production in e+e- collisions. We find that is it possible to evade the stringent bounds for natural regions of the parameters, while retaining finite separations between the fermion fields and without introducing a new hierarchy. The resulting limits on the size of the compact dimension can be as low as TeV-1
Flavor constraints on split fermion models
We examine the contributions to rare processes that arise in models where the standard model fermions are localized at distinct points in compact extra dimensions. Tree-level flavor changing neutral current interactions for the Kaluza-Klein gauge field excitations are induced in such models, and hence strong constraints are thought to exist on the size of the additional dimensions. We find a general parametrization of the model which does not depend on any specific fermion geography and show that typical values of the parameters can reproduce the fermion hierarchy pattern. Using this parametrization, we reexamine the contributions to neutral meson mixing, rare meson decays, and single top-quark production in e+e- collisions. We find that it is possible to evade the stringent bounds for natural regions of the parameters, while retaining finite separations between the fermion fields and without introducing a new hierarchy. The resulting limits on the size of the compact dimension can be as low as TeV-1
Topology optimization of structures with stress constraints: Aeronautical applications
Topology optimization of structures is nowadays the most active and widely studied branch in structural optimization. This paper develops a minimum weight formulation for the topology optimization of continuum structures. This approach also includes stress constraints and addresses important topics like the efficient treatment of a large number of stress constraints, the approach of discrete solutions by using continuum design variables and the computational cost. The proposed formulation means an alternative to maximum stiffness formulations and offers additional advantages. The minimum weight formulation proposed is based on the minimization of the weight of the structure. In addition, stress constraints are included in order to guarantee the feasibility of the final solution obtained. The objective function proposed has been designed to force the convergence to a discrete solution in the final stages of the optimization process. Thus, near discrete solutions are obtained by using continuum design variables. The robustness and reliability of the proposed formulation are verified by solving application examples related to aeronautical industry.
Cosmological constraints in the presence of ionizing and resonance radiation at recombination
With the recent measurement of full sky cosmic microwave background (CMB) polarization from WMAP, key cosmological degeneracies have been broken, allowing tighter constraints to be placed on cosmological parameters inferred assuming a standard recombination scenario. Here we consider the effect on cosmological constraints if additional ionizing and resonance radiation sources are present at recombination. We find that the new CMB data significantly improve the constraints on the additional radiation sources, with log10[εα]10[εi]s are weakened to ns=0.98±0.03, with the ns=1 case now well inside the 95% c.l. The relaxation of constraints on tensor modes, scale invariance, dark energy and neutrino masses are also discussed
无
2011-01-01
On May 1,China will begin to ban the production and use of two food additives commonly used to "bleach" flour,benzoyl peroxide and calcium peroxide.The decision was made after 10 years of wrangling between the policy makers,manufacturers,scientists and consumers.The Ministry of Health said in a statement it was applying the ban in response to consumers’ concerns about chemical substances in food,and technical improvements that had made the two additives unnecessary in flour processing.Minister of Health Chen Zhu has also said
Ritz, Christian; Streibig, Jens Carl
2014-01-01
Interest in synergistic or antagonistic effects through mixture experiments has grown immensely over the past two decades, not the least within in pharmacology and toxicology. Several definitions of reference models exist; one commonly used reference model is concentration or dose addition, which...... assumes compounds, when administrated simultaneously, do not interfere with each other at the site of action. We focus on statistical modelling that allows evaluation of dose addition. We will describe several statistical approaches that are suitable for analysis mixture data where synergistic or...
Constraints on heavy Z' couplings from \\Delta S = 2 B^- -> K^- K^- \\pi^+ decay
Fajfer, S.; Singer, P
2001-01-01
The heavy Z' boson with family nonuniversal couplings can introduce flavour changing effects. Constraints on nondiagonal Z' couplings coming from the \\mu-e conversion in a muonic atom, K^0 - \\bar{K^0} and B - \\bar{B} mixing, epsilon and epsilon'/ \\epsilon CP- violating coefficients have been already established. By using the OPAL upper bound of the branching ratio for the B^- -> K^- K^- \\pi^+ decay, we indicate additional constraints on the Z' couplings. We comment also on the constraints of ...
Sloppy Addition and Multiplication
Nannarelli, Alberto
Sometimes reducing the precision of a numerical processor, by introducing errors, can lead to significant performance (delay, area and power dissipation) improvements without compromising the overall quality of the processing. In this work, we show how to perform the two basic operations, addition...
Planck 2016 intermediate results. XLVII. Planck constraints on reionization history
Adam, R; Ashdown, M; Aumont, J; Baccigalupi, C; Ballardini, M; Banday, A J; Barreiro, R B; Bartolo, N; Basak, S; Battye, R; Benabed, K; Bernard, J -P; Bersanelli, M; Bielewicz, P; Bock, J J; Bonaldi, A; Bonavera, L; Bond, J R; Borrill, J; Bouchet, F R; Bucher, M; Burigana, C; Calabrese, E; Cardoso, J -F; Carron, J; Chiang, H C; Colombo, L P L; Combet, C; Comis, B; Coulais, A; Crill, B P; Curto, A; Cuttaia, F; Davis, R J; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Di Valentino, E; Dickinson, C; Diego, J M; Doré, O; Douspis, M; Ducout, A; Dupac, X; Elsner, F; Enßlin, T A; Eriksen, H K; Falgarone, E; Fantaye, Y; Finelli, F; Forastieri, F; Frailis, M; Fraisse, A A; Franceschi, E; Frolov, A; Galeotta, S; Galli, S; Ganga, K; Génova-Santos, R T; Gerbino, M; Ghosh, T; González-Nuevo, J; Górski, K M; Gruppuso, A; Gudmundsson, J E; Hansen, F K; Helou, G; Henrot-Versillé, S; Herranz, D; Hivon, E; Huang, Z; Ili_, S; Jaffe, A H; Jones, W C; Keihänen, E; Keskitalo, R; Kisner, T S; Knox, L; Krachmalnicoff, N; Kunz, M; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Langer, M; Lasenby, A; Lattanzi, M; Lawrence, C R; Jeune, M Le; Levrier, F; Lewis, A; Liguori, M; Lilje, P B; López-Caniego, M; Ma, Y -Z; Macías-Pérez, J F; Maggio, G; Mangilli, A; Maris, M; Martin, P G; Martínez-González, E; Matarrese, S; Mauri, N; McEwen, J D; Meinhold, P R; Melchiorri, A; Mennella, A; Migliaccio, M; Miville-Deschênes, M -A; Molinari, D; Moneti, A; Montier, L; Morgante, G; Moss, A; Naselsky, P; Natoli, P; Oxborrow, C A; Pagano, L; Paoletti, D; Partridge, B; Patanchon, G; Patrizii, L; Perdereau, O; Perotto, L; Pettorino, V; Piacentini, F; Plaszczynski, S; Polastri, L; Polenta, G; Puget, J -L; Rachen, J P; Racine, B; Reinecke, M; Remazeilles, M; Renzi, A; Rocha, G; Rossetti, M; Roudier, G; Rubiño-Martín, J A; Ruiz-Granados, B; Salvati, L; Sandri, M; Savelainen, M; Scott, D; Sirri, G; Sunyaev, R; Suur-Uski, A -S; Tauber, J A; Tenti, M; Toffolatti, L; Tomasi, M; Tristram, M; Trombetti, T; Valiviita, J; Van Tent, F; Vielva, P; Villa, F; Vittorio, N; Wandelt, B D; Wehus, I K; White, M; Zacchei, A; Zonca, A
2016-01-01
We investigate constraints on cosmic reionization extracted from the Planck cosmic microwave background (CMB) data. We combine the Planck CMB anisotropy data in temperature with the low-multipole polarization data to fit {\\Lambda}CDM models with various parameterizations of the reionization history. We obtain a Thomson optical depth {\\tau}=0.058 +/- 0.012 for the commonly adopted instantaneous reionization model. This confirms, with only data from CMB anisotropies, the low value suggested by combining Planck 2015 results with other data sets and also reduces the uncertainties. We reconstruct the history of the ionization fraction using either a symmetric or an asymmetric model for the transition between the neutral and ionized phases. To determine better constraints on the duration of the reionization process, we also make use of measurements of the amplitude of the kinetic Sunyaev-Zeldovich (kSZ) effect using additional information from the high resolution Atacama Cosmology Telescope and South Pole Telescope...
Since the end of the cold war a series of events has changed the circumstances and requirements of the safeguards system. The discovery of a clandestine nuclear weapons program in Iraq, the continuing difficulty in verifying the initial report of Democratic People's Republic of Korea upon entry into force of their safeguards agreement, and the decision of the South African Government to give up its nuclear weapons program and join the Treaty on the Non-Proliferation of Nuclear Weapons have all played a role in an ambitious effort by IAEA Member States and the Secretariat to strengthen the safeguards system. A major milestone in this effort was reached in May 1997 when the IAEA Board of Governors approved a Model Protocol Additional to Safeguards Agreements. The Model Additional Protocol was negotiated over a period of less than a year by an open-ended committee of the Board involving some 70 Member States and two regional inspectorates. The IAEA is now in the process of negotiating additional protocols, State by State, and implementing them. These additional protocols will provide the IAEA with rights of access to information about all activities related to the use of nuclear material in States with comprehensive safeguards agreements and greatly expanded physical access for IAEA inspectors to confirm or verify this information. In conjunction with this, the IAEA is working on the integration of these measures with those provided for in comprehensive safeguards agreements, with a view to maximizing the effectiveness and efficiency, within available resources, the implementation of safeguards. Details concerning the Model Additional Protocol are given. (author)
Constraints on lepton number violating short-range interactions from $|\\Delta L|=2$ processes
Quintero, Nestor
2016-01-01
In this work we study the short-range contributions that induce effective lepton number violating (LNV) interactions. We obtain a full set of constraints on the effective short-range couplings from a large variety of low-energy $|\\Delta L|= 2$ processes of pseudoscalar mesons $K, D, D_s, B$, and $\\tau$-lepton. These constraints provide complementary and additional information to the one obtained from the neutrinoless double-$\\beta$ ($0\
Collider Constraints and Prospects of a Scalar Singlet Extension to Higgs Portal Dark Matter
Dupuis, Grace
2016-01-01
This work considers an extension of the Standard Model (SM) Higgs sector by a real, scalar singlet field, including applicability to a dark matter (DM) model with the addition of a Yukawa coupling to a Dirac fermion. The collider signatures and constraints on the mixed two-Higgs scenario are determined, including limits from Higgs production signals and exclusion searches, as well as constraints arising from the Higgs total and invisible widths. As there is overwhelming Higgs data which is co...
a Chiral Schwinger Model, its Constraint Structure and Applications to its Quantization
Bracken, Paul
The Jackiw-Rajaraman version of the chiral Schwinger model is studied as a function of the renormalization parameter. The constraints are obtained and they are used to carry out canonical quantization of the model by means of Dirac brackets. By introducing an additional scalar field, it is shown that the model can be made gauge invariant. The gauge invariant model is quantized by establishing a pair of gauge fixing constraints in order that the method of Dirac can be used.
A Chiral Schwinger model, its Constraint Structure and Applications to its Quantization
Bracken, Paul
2007-01-01
The Jackiw-Rajaraman version of the chiral Schwinger model is studied as a function of the renormalization parameter. The constraints are obtained and they are used to carry out canonical quantization of the model by means of Dirac brackets. By introducing an additional scalar field, it is shown that the model can be made gauge invariant. The gauge invariant model is quantized by establishing a pair of gauge fixing constraints in order that the method of Dirac can be used.
A Chiral Schwinger model, its Constraint Structure and Applications to its Quantization
Bracken, Paul
2007-01-01
The Jackiw-Rajaraman version of the chiral Schwinger model is studied as a function of the renormalization parameter. The constraints are obtained and they are used to carry out canonical quantization of the model by means of Dirac brackets. By introducing an additional scalar field, it is shown that the model can be made gauge invariant. The gauge invariant model is quantized by establishing a pair of gauge fixing constraints, so the method of Dirac can be used.
Functional Modeling of Constraint Management in Aviation Safety and Command and Control
Woltjer, Rogier
2009-01-01
This thesis has shown that the concept of constraint management is instrumental in understanding the domains of command and control and aviation safety. Particularly, functional modeling as a means to address constraint management provides a basis for analyzing the performance of socio-technical systems. In addition to the theoretical underpinnings, six studies are presented. First, a functional analysis of an exercise conducted by a team of electricity network emergency managers is...
QCD unitarity constraints on Reggeon Field Theory
Kovner, Alex; Lublinsky, Michael
2016-01-01
We point out that the 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
Kovner, Alex; Levin, Eugene; Lublinsky, Michael
2016-08-01
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.
Expressing Model Constraints Visually with VMQL
Störrle, Harald
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......) 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...
Constraint satisfaction problems CSP formalisms and techniques
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
Modifier constraints in alkali ultraphosphate glasses
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...... limitation of BCT can be overcome. The modifiers are considered to exist in either “isolated” or “crosslinking” sites, in line with the so-called modifier sub-network [J. Chem. Phys. 140, 154501 (2014)] and each site is associated with a certain number of constraints. We estimate the compositional dependence...
Database queries and constraints via lifting problems
Spivak, David I
2012-01-01
Previous work has shown a tight relationship between databases and categories. In the present paper we extend that connection to show that certain queries and constraints correspond to the algebro-topological notion of lifting problems. In our formulation, each so-called SPARQL graph pattern query corresponds to a lifting problem, and each solution to the query corresponds to a lift. We interpret constraints within the same formalism and then investigate some formal properties of queries and constraints, e.g. their behavior under data migration functors.
Black hole thermodynamics from Euclidean horizon constraints.
Carlip, S
2007-07-13
To explain black hole thermodynamics in quantum gravity, one must introduce constraints to ensure that a black hole is actually present. I show that for a large class of black holes, such "horizon constraints" allow the use of conformal field theory techniques to compute the density of states, reproducing the Bekenstein-Hawking entropy in a nearly model-independent manner. One standard string theory approach to black hole entropy arises as a special case, lending support to the claim that the mechanism may be "universal." I argue that the relevant degrees of freedom are Goldstone-boson-like excitations arising from the weak breaking of symmetry by the constraints. PMID:17678209
Nathanson, Melvyn B.
2006-01-01
The quantum integer $[n]_q$ is the polynomial $1 + q + q^2 + ... + q^{n-1}.$ Two sequences of polynomials $\\mathcal{U} = \\{u_n(q)\\}_{n=1}^{\\infty}$ and $\\mathcal{V} = \\{v_n(q)\\}_{n=1}^{\\infty}$ define a {\\em linear addition rule} $\\oplus$ on a sequence $\\mathcal{F} = \\{f_n(q)\\}_{n=1}^{\\infty}$ by $f_m(q)\\oplus f_n(q) = u_n(q)f_m(q) + v_m(q)f_n(q).$ This is called a {\\em quantum addition rule} if $[m]_q \\oplus [n]_q = [m+n]_q$ for all positive integers $m$ and $n$. In this paper all linear qua...
Sinovec Zlatan J.; Jokić Živan; Šefer Dragan
2002-01-01
To attain better feed utilization, longer preservation, easier manipultion and higher production and better quality of food of animal orgin as the final goal, besides raw materials, feed mixes contain numerous pronutrients (additives), added to perform different effects, in a narrower sense, the term pronutrient implies heterogenous substances, which have no diverse effects and have to be efficient in the manner of use. Basically, all pronutrients have to reach the goal of keeping optimal ani...
Purpose: Although several institutions have reported rectal dose constraints according to threshold toxicity, the plethora of trials has resulted in multiple, confusing dose-volume histogram recommendations. A set of standardized, literature-based constraints for patients undergoing whole pelvic radiotherapy (RT) for prostate cancer would help guide the practice of prostate RT. The purpose of this study was to develop these constraints, demonstrate that they are achievable, and assess the corresponding rectal toxicity. Methods and Materials: An extensive literature search identified eight key studies relating dose-volume histogram data to rectal toxicity. A correction factor was developed to address differences in the anatomic definition of the rectum across studies. The dose-volume histogram constraints recommended by each study were combined to generate the constraints. The data from all patients treated with definitive intensity-modulated RT were then compared against these constraints. Acute rectal toxicity was assessed. Results: A continuous, proposed rectal dose-constraint curve was generated. Intensity-modulated RT not only met this constraint curve, but also was able to achieve at least 30-40% lower dose to the rectum. The preliminary clinical results were also positive: 50% of patients reported no acute bowel toxicity, 33% reported Grade 1 toxicity, and 17% reported Grade 2 toxicity. No patients reported Grade 3-4 acute rectal toxicity. Conclusions: In this study, we developed a set of proposed rectal dose constraints. This allowed for volumetric assessment of the dose-volume relationship compared with single dose-volume histogram points. Additional research will be performed to validate this threshold as a class solution for rectal dose constraints
Optimal accounting policies under financial constraints: aggressive versus conservative
Masatomo Akita; Yusuke Osaki
2011-01-01
We examine how severity of financial constraints influences firms' choices of accounting policies. This paper shows that firms with mild financial constraints choose an aggressive accounting policy and those with severe financial constraints choose a conservative accounting policy.
Choco: an Open Source Java Constraint Programming Library
Jussien, Narendra; Rochart, Guillaume; Lorca, Xavier
2008-01-01
Choco is a java library for constraint satisfaction problems (CSP), constraint programming (CP) and explanation-based constraint solving (e-CP). It is built on a event-based propagation mechanism with backtrackable structures.
Optimal portfolio strategies under a shortfall constraint
D Akuma
2009-06-01
Full Text Available We impose dynamically, a shortfall constraint in terms of Tail Conditional Expectation on the portfolio selection problem in continuous time, in order to obtain optimal strategies. The financial market is assumed to comprise n risky assets driven by geometric Brownian motion and one risk-free asset. The method of Lagrange multipliers is combined with the Hamilton-Jacobi-Bellman equation to insert the constraint into the resolution framework. The constraint is re-calculated at short intervals of time throughout the investment horizon. A numerical method is applied to obtain an approximate solution to the problem. It is found that the imposition of the constraint curbs investment in the risky assets.
Dynamic shortfall constraints for optimal portfolios
Bernd Luderer
2010-06-01
Full Text Available We consider a portfolio problem when a Tail Conditional Expectation constraint is imposed. The financial market is composed of n risky assets driven by geometric Brownian motion and one risk-free asset. The Tail Conditional Expectation is calculated for short intervals of time and imposed as risk constraint dynamically. The method of Lagrange multipliers is combined with the Hamilton-Jacobi-Bellman equation to insert the constraint into the resolution framework. A numerical method is applied to obtain an approximate solution to the problem. We find that the imposition of the Tail Conditional Expectation constraint when risky assets evolve following a log-normal distribution, curbs investment in the risky assets and diverts the wealth to consumption.
More general BBN constraints on neutrino oscillations
Stringent constraints on active-sterile neutrino oscillations were obtained from cosmology. However, mainly the case of initially zero νs state δNs = 0 was considered. We study cosmological constraints on νe ↔ νs oscillations for the case when νe is partially filled initially, i.e. 0 2 4He, in the presence of νe ↔ νs oscillations, effective after neutrino decoupling. We account for all known oscillations effects on cosmological nucleosynthesis. We calculate the cosmological constraints on oscillation parameters corresponding to non-zero initial population of the sterile state and 5% 4He overproduction. These generalized cosmological constraints corresponding to δN2 > 0 are relaxed in comparison to the δN2 = 0 case and the relaxation is proportional to δN2. (author)
Availability constraints in the Housing Market.
Rouwendal, J.; Palma, de A.
1996-01-01
This paper studies the consequences of probalistic availability constraints in the housing market for the specification and estimation of discrete choice models. An empirical application concerns the regulated rental part of the Dutch housing market
Reactive Imperative Programming with Dataflow Constraints
Demetrescu, Camil; Ribichini, Andrea
2011-01-01
Dataflow languages provide natural support for specifying constraints between objects in dynamic applications, where programs need to react efficiently to changes of their environment. Researchers have long investigated how to take advantage of dataflow constraints by embedding them into procedural languages. Previous mixed imperative/dataflow systems, however, require syntactic extensions or libraries of ad hoc data types for binding the imperative program to the dataflow solver. In this paper we propose a novel approach that smoothly combines the two paradigms without placing undue burden on the programmer. In our framework, programmers can define ordinary commands of the host imperative language that enforce constraints between objects stored in "reactive" memory locations. Reactive objects can be of any legal type in the host language, including primitive data types, pointers, arrays, and structures. Constraints are automatically re-executed every time their input memory locations change, letting a progra...
Equilibrium Macroscopic Structure Revisited from Spatial Constraint
Yuge, Koretaka
2016-02-01
In classical systems, we reexamine how macroscopic structures in equilibrium state connect with spatial constraint on the systems. For example, volume and density as the constraint for liquids in rigid box, and crystal lattice as the constraint for crystalline solids. We find that in disordered states, equilibrium macroscopic structure, depending on temperature and on multibody interactions in the system, can be well characterized by a single special microscopic structure independent of temperature and of interactions. The special microscopic structure depends only on the spatial constraint. We demonstrate the present findings providing (i) significantly efficient and systematic prediction of macroscopic structures for possible combination of constituents in multicomponent systems using first-principles calculations, and (ii) unique and accurate prediction of multibody interactions in given system from measured macroscopic structure, without performing trial-and-error simulation.
Extending models for two-dimensional constraints
Forchhammer, Søren
2009-01-01
Random fields in two dimensions may be specified on 2 times 2 elements such that the probabilities of finite configurations and the entropy may be calculated explicitly. The Pickard random field is one example where probability of a new (non-boundary) element is conditioned on three previous...... models of two-dimensional constraints and as examples we apply it to the hard-square constraint and the no isolated bits (n.i.b) constraint. The iterative scaling can ensure that the entropy of the extension is optimized and that the entropy is increased compared to the initial model defined on 2 times 2...... elements. Application to a simple stationary model with hidden states is also outlined. For the n.i.b constraint, the initial model is based on elements defined by blocks of (1 times 2) binary symbols....
AUTOMATIC APPROACH TO PRODUCT CONCEPTUAL DESIGN BASED ON CONSTRAINT NETWORK
Li Hongjie; Xiao Renbin
2004-01-01
Product design is considered as the constraint satisfaction problem (CSP), and a new design approach basedon constraint network is proposed and applied to make design automatic partially. By means of constraint extraction, constraint network construction and operation, constraint chains are acquired, and then the conceptual design scheme can be got by decoding the information stored in the design constraint chains, which provides a novelty method for mechanical product design automation. Shearing mechanism of shearing machine has been designed by this way.
Software Architecture Constraint Reuse-by-Composition
Tibermacine, Chouki; Sadou, Salah; Ton That, Tu Minh; Dony, Christophe
2016-01-01
International audience Architecture constraints are specifications which enable developers to formalize design rules that architectures should respect, like the topological conditions of a given architecture pattern or style. These constraints can serve as a documentation to better understand an existing architecture description , or can serve as invariants that can be checked after the application of an architecture change to see whether design rules still hold. Like any specifications , ...
Discretisations, Constraints and Diffeomorphisms in Quantum Gravity
Benjamin Bahr
2012-01-01
Full Text Available In this review we discuss the interplay between discretization, constraint implementation, and diffeomorphism symmetry in Loop Quantum Gravity and Spin Foam models. To this end we review the Consistent Discretizations approach, which is an application of the master constraint program to construct the physical Hilbert space of the canonical theory, as well as the Perfect Actions approach, which aims at finding a path integral measure with the correct symmetry behavior under diffeomorphisms.
Constraint Aggregation Principle in Convex Optimization
Y.M. Ermoliev; Kryazhimskiy, A.V.; Ruszczynski, A.
1995-01-01
A general constraint aggregation technique is proposed for convex optimization problems. At each iteration a set of convex inequalities and linear equations is replaced by a single inequality formed as a linear combination of the original constraints. After solving the simplified subproblem, new aggregation coefficients are calculated and the iteration continues. This general aggregation principle is incorporated into a number of specific algorithms. Convergence of the new methods is pro...
Exploiting Semidefinite Relaxations in Constraint Programming
van Hoeve, Willem Jan
2004-01-01
Constraint programming uses enumeration and search tree pruning to solve combinatorial optimization problems. In order to speed up this solution process, we investigate the use of semidefinite relaxations within constraint programming. In principle, we use the solution of a semidefinite relaxation to guide the traversal of the search tree, using a limited discrepancy search strategy. Furthermore, a semidefinite relaxation produces a bound for the solution value, which is used to prune parts o...
An Introductory Course on Constraint Logic Programming
Carro Liñares, Manuel; Hermenegildo, Manuel V.; Bueno Carrillo, Francisco; Cabeza Gras, Daniel; García de la Banda, M; López García, Pedro
1998-01-01
The purpose of this document is to serve as the printed material for the seminar "An Introductory Course on Constraint Logic Programming". The intended audience of this seminar are industrial programmers with a degree in Computer Science but little previous experience with constraint programming. The seminar itself has been field tested, prior to the writing of this document, with a group of the application programmers of Esprit project P23182, "VOCAL", aimed at developing an application in s...
Collateral constraints, idiosyncratic risk, and aggregate fluctuations
Brumm, Johannes
2011-01-01
Theoretically, collateral constraints have the potential to strongly amplify and propagate aggregate shocks. However, the quantitative literature tends to find rather weak and non-robust effects. This paper tries to improve on this by modeling the interaction between idiosyncratic risk and collateral constraints. To this aim, agents' productivities as workers and entrepreneurs are assumed to evolve stochastically. This leads to a perpetual mismatch between wealth and skills, which is the reas...
Algorithms for stochastic optimization with expectation constraints
Lan, Guanghui; Zhou, Zhiqiang
2016-01-01
This paper considers the problem of minimizing an expectation function over a closed convex set, coupled with functional constraints given in the form of expectation. We present a new stochastic approximation (SA) type algorithm, namely the alternating mirror-descent SA (AMD-SA) algorithm, to minimize these expectation constrained problems, and show that it exhibits the optimal rate of convergence when the objective and constraint functions are convex or strongly convex. We also present a var...
Participation constraints in ski: measurement model validation
Rodrigues, Pedro Miguel Monteiro; Botelho, Jéssica; Sadio, Alexandre; Miguel-Dávila, José Ángel
2012-01-01
Aim of abstract/paper - research question Sport Participation (SP) is one of the most studied subjects among the available leisure and sport literature. SP has been studied from different perspectives. In this context, constraints represent a large proportion of the adopted approaches. Although these have been indiscriminately adopted, constraints approaches are particularly relevant in studies that focus on the general population or in non participants samples....
Constraint-based specifications for system configuration
Hewson, John Aubrey
2013-01-01
Declarative, object-oriented configuration management systems are widely used, and there is a desire to extend such systems with automated analysis and decision-making. This thesis introduces a new formulation for configuration management problems based on the tools and techniques of constraint programming, which enables automated decision-making. We present ConfSolve, an object-oriented declarative configuration language, in which logical constraints on a system can be spec...
Optimal capital stock and financing constraints
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.
Proving correctness of Timed Concurrent Constraint Programs
de Boer, F.S.; Gabbrielli, M.; Meo, M.C.
2002-01-01
A temporal logic is presented for reasoning about the correctness of timed concurrent constraint programs. The logic is based on modalities which allow one to specify what a process produces as a reaction to what its environment inputs. These modalities provide an assumption/commitment style of specification which allows a sound and complete compositional axiomatization of the reactive behavior of timed concurrent constraint programs.
Constraint Programming and Combinatorial Optimisation in Numberjack
Hébrard, Emmanuel; Eoin, O'Mahony; Barry, O'Sullivan
2010-01-01
Python benets from a large and active programming com- munity. Numberjack is a modelling package written in Python for embed- ding constraint programming and combinatorial optimisation into larger applications. It has been designed to seamlessly and efficiently support a number of underlying combinatorial solvers. Currently, Numberjack supports three constraint programming solvers, one MIP solver, and one satisability solver -- all available as open-source software. This paper illustrates man...
TRENDS AND CONSTRAINTS IN CLT IN CHINA
GuoHongjie; NiChuanbin
2004-01-01
Communicative language teaching (CLT) is an in novationin English language teaching ( ELT ). That appeared in Britain in the late 1960s. As the country with the largest English learning population in the world, China also has become deeply involved in CLT. This essay attempts to sketch the trends of CLT in China, the constraints it met with, and outlines suggestions and measures taken to overcome the constraints.
Optimization Bicriteria Linear Programming Constraint Fuzzy Triangular
Pratama, Lintang Gilang
2014-01-01
This final project is to make a algorithm Bicriteria Linear Programming with constraint is triangular fuzzy number. The method used in this research is download-right defuzzyfication bicriteria linear programming problems with fuzzy rules in fuzzy sets and fuzzy number operations. Resolving sub-bicriteria problem of fuzzy linear programming with Parametric Simplex Algorithm in which every constraint has become a firm number and efficient (optimum) result is the form of best eff...
Sinovec Zlatan J.
2002-01-01
Full Text Available To attain better feed utilization, longer preservation, easier manipultion and higher production and better quality of food of animal orgin as the final goal, besides raw materials, feed mixes contain numerous pronutrients (additives, added to perform different effects, in a narrower sense, the term pronutrient implies heterogenous substances, which have no diverse effects and have to be efficient in the manner of use. Basically, all pronutrients have to reach the goal of keeping optimal animal health status and to increase production of food of animal origin without adverse and negative effects. The development of biotechnology had a great part in the appearance of natural alternatives which are able to fulfil and satisfy the high demands of highly productive animals, as well as those of the consumer lobby and environmental protection movements. Growth promoters based upon physiological mechanisms and production potential of the animal have an unquestionable adventage, not only because of the lack of residues in food of animal origin; but also because of their ecological safety and decrease of envirnomental pollution by undigested materials. Demand continues to grow for "all natural", non-pharmaceutical feed additives with growth enhancing effects in food animals. Special attention is paid to minerals (anorganic and organic sources, growth stimulators (antibiotics, probiotics prebiotics, substances for better feed utilization (enzymes, acidifers adsorbents.
Implementation of Complex Projects Using Constraint Programming
Miodrag Strak
2012-09-01
Full Text Available During the implementation of the complex projects, all planned activities and resources must be taken into account. In general, it is necessary to assign the resources to the activities, but to also avoid simultaneous engagement of resources for multiple activities. In order to solve these problems, various techniques and methods are used. Mathematic and integer programming, genetic algorithms, simulated annealing, or taboo search are just some of the techniques used for solving this problem. Constraint programming comes from artificial intelligence i.e. papers from this area that occurred in 1960s and 1970s. Constraints exist in every segment of human environment. They represent a natural medium for expressing relations that exist in the physical world. Fulfilment of constraints is used in many different areas. Problems such as scheduling, allocations etc. are typical examples of constraints problems, where the basic concept of constraint programming can be applied. This paper considered implementation of the Bor Regional Development Project. Development of constraint programming was followed by the development of appropriate tools. B-Prolog was used in this paper. Many systems, including B-Prolog, enable interface with classic object-oriented languages, such as C++ or Java. One of the greatest advantages is the possibility of simple modelling, even for beginners in planning and implementation of the project.
Autonomous gliding entry guidance with geographic constraints
Guo Jie; Wu Xuzhong; Tang Shengjing
2015-01-01
This paper presents a novel three-dimensional autonomous entry guidance for relatively high lift-to-drag ratio vehicles satisfying geographic constraints and other path constraints. The guidance is composed of onboard trajectory planning and robust trajectory tracking. For trajectory planning, a longitudinal sub-planner is introduced to generate a feasible drag-versus-energy profile by using the interpolation between upper boundary and lower boundary of entry corridor to get the desired trajectory length. The associated magnitude of the bank angle can be specified by drag profile, while the sign of bank angle is determined by lateral sub-planner. Two-reverse mode is utilized to satisfy waypoint constraints and dynamic heading error corridor is utilized to satisfy no-fly zone constraints. The longitudinal and lateral sub-planners are iteratively employed until all of the path constraints are satisfied. For trajectory tracking, a novel tracking law based on the active disturbance rejection control is introduced. Finally, adaptability tests and Monte Carlo simulations of the entry guidance approach are performed. Results show that the proposed entry guidance approach can adapt to different entry missions and is able to make the vehicle reach the prescribed target point precisely in spite of geographic constraints.
Improved Parameterized Algorithms for Constraint Satisfaction
Kim, Eun Jung
2010-01-01
Results from inapproximability provide several sharp thresholds on the approximability of important optimization problems. We give several improved parameterized algorithms for solving constraint satisfaction problems above a tight threshold. Our results include the following: - Improved algorithms for any Constraint Satisfaction Problem: Take any boolean Max-CSP with at most $c$ variables per constraint such that a random assignment satisfies a constraint with probability $p$. There is an algorithm such that for every instance of the problem with $m$ constraints, the algorithm decides whether at least $pm+k$ constraints can be satisfied in $O(2^{(c(c+1)/2) k} m)$ time. This improves on results of [Alon et al., SODA 2010] and [Crowston et al., SWAT 2010]. We observe that an $O(2^{\\eps k + \\eps m})$ time algorithm for every $\\eps > 0$ would imply that 3SAT is in subexponential time, so it seems unlikely that our runtime dependence on $k$ can be significantly improved. Our proof also shows that every Max-$c$-CS...
Ring-Constraint High-Pressure Torsion Process
Joo, Soo-Hyun; Kim, Hyoung Seop
2016-04-01
In this study, a constraint ring around a workpiece was employed in order to develop back pressure in addition to a compressive die pressure in high-pressure torsion (HPT) process. The influence of the constraint ring during the HPT process was analyzed using the finite element method and experimental analyses. Greater back pressure was developed when a ring of a stronger material enveloped the workpiece. In the experiments, fracture of a brittle material [e.g., La-based bulk metallic glass (BMG)], was limited even at large shear strain (~315) during the ring-constraint HPT (RC-HPT) process due to reduced tensile stress at the edge of the deforming BMG workpiece. Furthermore, the RC-HPT process had beneficial effects on powder consolidation and bonding. The RC-HPT process exhibited smaller loss of material than did the conventional semi-constrained HPT process. The Cu disk produced by the powder RC-HPT had smaller grain sizes because back pressure generated more dislocations and finer grain size in the Cu workpiece.
Complexities and constraints influencing learner performance in physical science
Mavhungu Abel Mafukata
2016-01-01
Full Text Available This paper explores complexities and constraints affecting performance and output of physical science learners in Vhembe District, Limpopo Province, South Africa. The study was motivated by the desire of the researcher to establish, profile and characterise the complexities and constraints reminiscence of poor performance of learners in physical science as measured through end-of-year Grade 12 (final year of high school education examination results. Twenty six schools (n=26 were purposively selected from three circuits of education (n=3. From these schools, two learners were randomly selected (n=52 for interviews. In addition, two circuit managers (n=2 were conveniently selected as part of Key Informant Interviews (KII. For the Focus Group Discussions (FGDs, twelve (n=12 parents were randomly selected to form two groups of six members each. Multi-factor complexities and constraints impeding performance of learners were discovered. Intensive teacher in-service programme is recommended. Community engagement should be encouraged to educate parents on the value of involvement in the education of their children. Free access learner support structures such as Homework and Extra-lessons Assistance Centre (H&EACs should be established.
Environmentally feasible potential for hydropower development regarding environmental constraints
In addition to technical and economical reasons, environmental impacts are becoming an increasingly important issue in the policy making of hydropower development. According to different spatial scales, environmental impacts of hydropower projects can be divided into environmental impacts around a plant and environmental impacts downstream. The former can be transformed into a uniformed quantification based on CO2 equivalent (CO2-e), while the latter can be quantified in terms of reduced downstream flow. Environmental constraints around a plant are presented as the minimum production of environmental impacts around a plant, while those downstream are presented as not affecting the downstream environmental flow requirements. Based on five large hydropower projects (LHPs) and 10 small hydropower projects (SHPs) cases in Tibet, China, LHPs have greater environmental impacts around a plant when compared with SHP, but the opposite is true for downstream environmental impacts. For environmental constraints around a plant and downstream, the environmentally feasible potential for hydropower development on the Lhasa River is 398.3 MW, which accounts for 15.6% of its theoretical potential, while the optimized hydropower mode choice is 285.7 MW for LHP and 112.6 MW for SHP. Environmentally feasible potential aims to balance hydropower generation with environmental protection, and tends to maximize the low carbon attributes of hydropower. - Highlights: • We propose an environmentally feasible potential (EFP) for hydropower development. • EFP depends on environmental constraints (EC) around a plant and EC downstream. • Environmentally feasible hydropower potential on the Lhasa River is 398.3 MW
Big bang nucleosynthesis and CMB constraints on dark energy
Current observational data favor cosmological models which differ from the standard model due to the presence of some form of dark energy and, perhaps, by additional contributions to the more familiar dark matter. Primordial nucleosynthesis provides a window on the very early evolution of the universe and constraints from big bang nucleosynthesis (BBN) can bound the parameters of models for dark matter or energy at redshifts of the order of ten billion. The spectrum of temperature fluctuations imprinted on the cosmic microwave background (CMB) radiation opens a completely different window on the universe at epochs from redshifts of the order of ten thousand to nearly the present. The CMB anisotropy spectrum provides constraints on new physics which are independent of and complementary to those from BBN. Here we consider three classes of models for the dark matter or energy: extra particles which were relativistic during the early evolution of the universe ('X'); quintessence models involving a minimally coupled scalar field ('Q'); models with a non-minimally coupled scalar field which modify the strength of gravity during the early evolution of the universe ('G'). We constrain the parameters of these models using data from BBN and the CMB and identify the allowed regions in their parameter spaces consistent with the more demanding joint BBN and CMB constraints. For 'X' and 'Q' such consistency is relatively easy to find; it is more difficult for the 'G' models with an inverse power law potential for the scalar field
Ring-Constraint High-Pressure Torsion Process
Joo, Soo-Hyun; Kim, Hyoung Seop
2016-07-01
In this study, a constraint ring around a workpiece was employed in order to develop back pressure in addition to a compressive die pressure in high-pressure torsion (HPT) process. The influence of the constraint ring during the HPT process was analyzed using the finite element method and experimental analyses. Greater back pressure was developed when a ring of a stronger material enveloped the workpiece. In the experiments, fracture of a brittle material [ e.g., La-based bulk metallic glass (BMG)], was limited even at large shear strain (~315) during the ring-constraint HPT (RC-HPT) process due to reduced tensile stress at the edge of the deforming BMG workpiece. Furthermore, the RC-HPT process had beneficial effects on powder consolidation and bonding. The RC-HPT process exhibited smaller loss of material than did the conventional semi-constrained HPT process. The Cu disk produced by the powder RC-HPT had smaller grain sizes because back pressure generated more dislocations and finer grain size in the Cu workpiece.
Dense baryonic matter: constraints from recent neutron star observations
Hell, Thomas
2014-01-01
Updated constraints from neutron star masses and radii impose stronger restrictions on the equation of state for baryonic matter at high densities and low temperatures. The existence of two-solar-mass neutron stars rules out many soft equations of state with prominent "exotic" compositions. The present work reviews the conditions required for the pressure as a function of baryon density in order to satisfy these new constraints. Several scenarios for sufficiently stiff equations of state are evaluated. The common starting point is a realistic description of both nuclear and neutron matter based on a chiral effective field theory approach to the nuclear many-body problem. Possible forms of hybrid matter featuring a quark core in the center of the star are discussed using a three-flavor Polyakov--Nambu--Jona-Lasinio (PNJL) model. It is found that a conventional equation of state based on nuclear chiral dynamics meets the astrophysical constraints. Hybrid matter generally turns out to be too soft unless addition...
Hemert, van, M.C.; Solnon, C.
2004-01-01
We compare two heuristic approaches, evolutionary computation and ant colony optimisation, and a complete tree-search approach, constraint programming, for solving binary constraint satisfaction problems. We experimentally show that, if evolutionary computation is far from being able to compete with the two other approaches, ant colony optimisation nearly always succeeds in finding a solution, so that it can actually compete with constraint programming. The resampling ratio is used to provide...
Radioactivity: additional tables
The following additional tables are presented to the annual report on radioactive discharges from the major establishments in the U.K.: 1) Radioactive gaseous effluent, trends in annual emissions, by site, (civil and M.O.D.) 2) Radioactive liquid effluent (radionuclides specified by authorisations), trends in annual discharges to surface and coastal waters: by site. 3) Liquid effluent (radionuclides not subject to separate limits): annual discharges to surface and coastal waters by site. 4) Isotopic composition of liquid effluent from CEGB stations, 1984. 5) Trends in the amount of radioactivity in waste dumped in the north-east Atlantic. 6) Trends in volume of waste disposed of at Drigg (by source of waste). 7) Solid waste: trends in volume disposed of and level of activity at some other disposal sites. 8) Radioactivity in samples of fish and shellfish: trends in concentrations. (UK)
Additive Pattern Database Heuristics
Felner, A; Korf, R E; 10.1613/jair.1480
2011-01-01
We explore a method for computing admissible heuristic evaluation functions for search problems. It utilizes pattern databases, which are precomputed tables of the exact cost of solving various subproblems of an existing problem. Unlike standard pattern database heuristics, however, we partition our problems into disjoint subproblems, so that the costs of solving the different subproblems can be added together without overestimating the cost of solving the original problem. Previously, we showed how to statically partition the sliding-tile puzzles into disjoint groups of tiles to compute an admissible heuristic, using the same partition for each state and problem instance. Here we extend the method and show that it applies to other domains as well. We also present another method for additive heuristics which we call dynamically partitioned pattern databases. Here we partition the problem into disjoint subproblems for each state of the search dynamically. We discuss the pros and cons of each of these methods a...
Perspectives on Additive Manufacturing
Bourell, David L.
2016-07-01
Additive manufacturing (AM) has skyrocketed in visibility commercially and in the public sector. This article describes the development of this field from early layered manufacturing approaches of photosculpture, topography, and material deposition. Certain precursors to modern AM processes are also briefly described. The growth of the field over the last 30 years is presented. Included is the standard delineation of AM technologies into seven broad categories. The economics of AM part generation is considered, and the impacts of the economics on application sectors are described. On the basis of current trends, the future outlook will include a convergence of AM fabricators, mass-produced AM fabricators, enabling of topology optimization designs, and specialization in the AM legal arena. Long-term developments with huge impact are organ printing and volume-based printing.
Teardrop bladder: additional considerations
Nine cases of teardrop bladder (TDB) seen at excretory urography are presented. In some of these patients, the iliopsoas muscles were at the upper limit of normal in size, and additional evaluation of the perivesical structures with computed tomography (CT) was necessary. CT demonstrated only hypertrophied muscles with or without perivesical fat. The psoas muscles and pelvic width were measured in 8 patients and compared with the measurements of a control group of males without TDB. Patients with TDB had large iliopsoas muscles and narrow pelves compared with the control group. The psoas muscle width/pelvic width ratio was significantly greater (p < 0.0005) in patients with TDB than in the control group, with values of 1.04 + 0.05 and 0.82 + 0.09, respectively. It is concluded that TDB is not an uncommon normal variant in black males. Both iliopsoas muscle hypertrophy and a narrow pelvis are factors that predispose a patient to TDB
Constraint-Muse: A Soft-Constraint Based System for Music Therapy
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.
Critical constraint on inflationary magnetogenesis
Fujita, Tomohiro
2014-01-01
Recently, there are several reports that the cosmic magnetic fields on Mpc scale in void region is larger than $\\sim 10^{-15}$G with an uncertainty of a few orders from the current blazar observations. On the other hand, in inflationary magnetogenesis models, additional primordial curvature perturbations are inevitably produced from iso-curvature perturbations due to generated electromagnetic fields. We explore such induced curvature perturbations in a model independent way and obtained a severe upper bound for the energy scale of inflation from the observed cosmic magnetic fields and the observed amplitude of the curvature perturbation, as $\\rho_{\\rm inf}^{1/4} < 300{\\rm MeV} \\times (B_{\\rm obs}/10^{-15}{\\rm G})^{-1}$ where $B_{\\rm obs}$ is the strength of the magnetic field at present. Therefore, without a dedicated low energy inflation model or an additional amplification of magnetic fields after inflation, inflationary magnetogenesis on Mpc scale is generally incompatible with CMB observations.
Critical constraint on inflationary magnetogenesis
Fujita, Tomohiro [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), TODIAS, the University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8583 (Japan); Yokoyama, Shuichiro, E-mail: tomohiro.fujita@ipmu.jp, E-mail: shu@icrr.u-tokyo.ac.jp [Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba, 277-8582 (Japan)
2014-03-01
Recently, there are several reports that the cosmic magnetic fields on Mpc scale in void region is larger than ∼ 10{sup −15}G with an uncertainty of a few orders from the current blazar observations. On the other hand, in inflationary magnetogenesis models, additional primordial curvature perturbations are inevitably produced from iso-curvature perturbations due to generated electromagnetic fields. We explore such induced curvature perturbations in a model independent way and obtained a severe upper bound for the energy scale of inflation from the observed cosmic magnetic fields and the observed amplitude of the curvature perturbation , as ρ{sub inf}{sup 1/4} < 300MeV × (B{sub obs}/10{sup −15}G){sup −1} where B{sub obs} is the strength of the magnetic field at present. Therefore, without a dedicated low energy inflation model or an additional amplification of magnetic fields after inflation, inflationary magnetogenesis on Mpc scale is generally incompatible with CMB observations.
Wang, Wenqing; Wang, Aihui; Yu, Limin; Han, Xuesong; Jiang, Guiyun; Weng, Changshui; Zhang, Hongwei; Zhou, Zhiqiang
2012-11-15
Stroke patients with hemiplegia exhibit flexor spasms in the upper limb and extensor spasms in the lower limb, and their movement patterns vary greatly. Constraint-induced movement therapy is an upper limb rehabilitation technique used in stroke patients with hemiplegia; however, studies of lower extremity rehabilitation are scarce. In this study, stroke patients with lower limb hemiplegia underwent conventional Bobath therapy for 4 weeks as baseline treatment, followed by constraint-induced movement therapy for an additional 4 weeks. The 10-m maximum walking speed and Berg balance scale scores significantly improved following treatment, and lower extremity motor function also improved. The results of functional MRI showed that constraint-induced movement therapy alleviates the reduction in cerebral functional activation in patients, which indicates activation of functional brain regions and a significant increase in cerebral blood perfusion. These results demonstrate that constraint-induced movement therapy promotes brain functional reorganization in stroke patients with lower limb hemiplegia. PMID:25337108
Bezerra, V B; Mostepanenko, V M; Romero, C
2014-01-01
We obtain stronger laboratory constraints on the coupling constants of axion-like particles to nucleons from measurements of the normal and lateral Casimir forces between sinusoidally corrugated surfaces of a sphere and a plate. For this purpose, the normal and lateral additional force arising in the experimental configurations due to two-axion exchange between protons and neutrons are calculated. Our constraints following from measurements of the normal and lateral Casimir forces are stronger than the laboratory constraints reported so far for masses of axion-like particles larger than 11eV and 8eV, respectively. A comparison between various laboratory constraints on the coupling constants of axion-like particles to nucleons obtained from the magnetometer measurements, Eotvos- and Cavendish-type experiments, and from the Casimir effect is performed over the wide range of masses of axion-like particles from 10^{-10}eV to 20eV.
Bezerra, V. B.; Klimchitskaya, G. L.; Mostepanenko, V. M.; Romero, C.
2014-09-01
We obtain stronger laboratory constraints on the coupling constants of axion-like particles to nucleons from measurements of the normal and lateral Casimir forces between sinusoidally corrugated surfaces of a sphere and a plate. For this purpose, the normal and lateral additional forces arising in the experimental configurations due to the two-axion exchange between protons and neutrons are calculated. Our constraints following from measurements of the normal and lateral Casimir forces are stronger than the laboratory constraints reported so far for masses of axion-like particles larger than 11 and 8 eV, respectively. A comparison between various laboratory constraints on the coupling constants of axion-like particles to nucleons obtained from the magnetometer measurements, Eötvos- and Cavendish-type experiments, and from the Casimir effect is performed over the wide range of masses of axion-like particles from 10-10 to 20 eV.
Oflazer, K; Oflazer, Kemal; Tur, Gokhan
1996-01-01
This paper presents a constraint-based morphological disambiguation approach that is applicable languages with complex morphology--specifically agglutinative languages with productive inflectional and derivational morphological phenomena. In certain respects, our approach has been motivated by Brill's recent work, but with the observation that his transformational approach is not directly applicable to languages like Turkish. Our system combines corpus independent hand-crafted constraint rules, constraint rules that are learned via unsupervised learning from a training corpus, and additional statistical information from the corpus to be morphologically disambiguated. The hand-crafted rules are linguistically motivated and tuned to improve precision without sacrificing recall. The unsupervised learning process produces two sets of rules: (i) choose rules which choose morphological parses of a lexical item satisfying constraint effectively discarding other parses, and (ii) delete rules, which delete parses sati...
Statistical constraints on state preparation for a quantum computer
Subhash Kak
2001-10-01
Quantum computing algorithms require that the quantum register be initially present in a superposition state. To achieve this, we consider the practical problem of creating a coherent superposition state of several qubits. We show that the constraints of quantum statistics require that the entropy of the system be brought down when several independent qubits are assembled together. In particular, we have: (i) not all initial states are realizable as pure states; (ii) the temperature of the system must be reduced. These factors, in addition to decoherence and sensitivity to errors, must be considered in the implementation of quantum computers.
Learning feature constraints in a chaotic neural memory
Nara, Shigetoshi; Davis, Peter
1997-01-01
We consider a neural network memory model that has both nonchaotic and chaotic regimes. The chaotic regime occurs for reduced neural connectivity. We show that it is possible to adapt the dynamics in the chaotic regime, by reinforcement learning, to learn multiple constraints on feature subsets. This results in chaotic pattern generation that is biased to generate the feature patterns that have received responses. Depending on the connectivity, there can be additional memory pulling effects, due to the correlations between the constrained neurons in the feature subsets and the other neurons.
Stabilization of linear higher derivative gravity with constraints
We show that the instabilities of higher derivative gravity models with quadratic curvature invariant αR2+βRμνRμν can be removed by judicious addition of constraints at the quadratic level of metric fluctuations around Minkowski/de Sitter background. With a suitable parameter choice, we find that the instabilities of helicity-0, 1, 2 modes can be removed while reducing the dimensionality of the original phase space. To retain the renormalization properties of higher derivative gravity, Lorentz symmetry in the constrained theory is explicitly broken
Dirac Constraint Quantization of a Dilatonic Model of Gravitational Collapse
Kuchar, K V; Varadarajan, M; Kuchar, Karel V.; Romano, Joseph D.; Varadarajan, Madhavan
1997-01-01
We present an anomaly-free Dirac constraint quantization of the string-inspired dilatonic gravity (the CGHS model) in an open 2-dimensional spacetime. We show that the quantum theory has the same degrees of freedom as the classical theory; namely, all the modes of the scalar field on an auxiliary flat background, supplemented by a single additional variable corresponding to the primordial component of the black hole mass. The functional Heisenberg equations of motion for these dynamical variables and their canonical conjugates are linear, and they have exactly the same form as the corresponding classical equations. A canonical transformation brings us back to the physical geometry and induces its quantization.
Best Tracking Performance under Plant Uncertainty and Control Energy Constraint
KONG Yi-gang; WANG Zhi-xin; WANG Jian-guo
2007-01-01
This paper has investigated best tracking performance for linear feedback control systems in the case that plant uncertainty and control effort need to be considered simultaneously. Firstly, an average integral square criterion of the tracking error and the plant input energy over a class of additive model errors is defined. Then, utilizing spectral factorization to minimize the performance index, we obtain an optimal controller design method, and furthermore study optimal tracking performance under plant uncertainty and control energy constraint. The results can be used to evaluate optimal average tracking performance and control energy in designing practical control systems.
Degree heterogeneity in spatial networks with total cost constraint
Liu, Weiping; Zeng, An; Zhou, Yanbo
2012-01-01
Recently, Li et al. (Phys. Rev. Lett., 104 (2010) 018701) studied a spatial network which is constructed from a regular lattice by adding long-range edges (shortcuts) with probability Pij~rij−α, where rij is the Manhattan length of the long-range edges. The total length of the additional edges is subject to a cost constraint (∑ r = C). This spatial network model displays an optimal exponent α for transportation (measured by the average shortest-path length). However, we observe that the degre...
Constraint-Guided Workflow Composition Based on the EDAM Ontology
Lamprecht, Anna-Lena; Steffen, Bernhard; Margaria, Tiziana
2010-01-01
Methods for the automatic composition of services into executable workflows need detailed knowledge about the application domain,in particular about the available services and their behavior in terms of input/output data descriptions. In this paper we discuss how the EMBRACE data and methods ontology (EDAM) can be used as background knowledge for the composition of bioinformatics workflows. We show by means of a small example domain that the EDAM knowledge facilitates finding possible workflows, but that additional knowledge is required to guide the search towards actually adequate solutions. We illustrate how the ability to flexibly formulate domain-specific and problem-specific constraints supports the work ow development process.
Formalizing the Evaluation of OCL Constraints
Gergely Mezei
2007-03-01
Full Text Available Domain-specific modeling has growing importance in many fields of softwareenginering, such as modeling control flows of data processing, or in man-machine systems.Customizable language dictionary and customizable notations of the model elementsoffered by domain-specific technologies make software systems easier to create andmaintain. However, visual model definitions have a tendency to be incomplete, orimprecise; the definitions can be extended by textual constraints attached to the modelitems. Textual constraints can eliminate the incompleteness stemming from the limitationsof the structural definition as well. The Object Constraint Language (OCL is one of themost popular constraint languages in the field of UML and Domain Specific ModelingLanguages. OCL is a flexible, yet formal language with a mathematical background.Existing formalisms of OCL does not describe dynamic behavior of constraints. Ourresearch aims at creating an OCL optimization solution and prove its correctness formally.However, the shortcomings of the existing formalism has led us to create a new formalism.The paper presents OCLASM, a new formalism for OCL, which can describe both thesemantics and the dynamical behavior of the language constructs, thus, it is capable ofdescribing proofs of optimization algortihms. OCLASM is based on the Abstract StateMachines technique.
Diffusion Processes Satisfying a Conservation Law Constraint
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.
Pair Production Constraints on Superluminal Neutrinos Revisited
Brodsky, Stanley J.; /SLAC; Gardner, Susan; /Kentucky U.
2012-02-16
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{sup 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.
Batty, Kimberly A.
2011-01-01
The purpose of this study was to document the factors (i.e., motivation and perceived constraints) and processes (i.e., constraint negotiation) that influence students' selection of and satisfaction with their internship choice. The study was conducted using a quantitative approach, which included a focus group, a pilot study, and a…
NMR Constraints Analyser: a web-server for the graphical analysis of NMR experimental constraints.
Heller, Davide Martin; Giorgetti, Alejandro
2010-07-01
Nuclear magnetic resonance (NMR) spectroscopy together with X-ray crystallography, are the main techniques used for the determination of high-resolution 3D structures of biological molecules. The output of an NMR experiment includes a set of lower and upper limits for the distances (constraints) between pairs of atoms. If the number of constraints is high enough, there will be a finite number of possible conformations (models) of the macromolecule satisfying the data. Thus, the more constraints are measured, the better defined these structures will be. The availability of a user-friendly tool able to help in the analysis and interpretation of the number of experimental constraints per residue, is thus of valuable importance when assessing the levels of structure definition of NMR solved biological macromolecules, in particular, when high-quality structures are needed in techniques such as, computational biology approaches, site-directed mutagenesis experiments and/or drug design. Here, we present a free publicly available web-server, i.e. NMR Constraints Analyser, which is aimed at providing an automatic graphical analysis of the NMR experimental constraints atom by atom. The NMR Constraints Analyser server is available from the web-page http://molsim.sci.univr.it/constraint. PMID:20513646
Effective constraint algebras with structure functions
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)
Lorentz violation. Motivation and new constraints
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.)
On inner constraints in plane circular arches
Ruta, G.C. [Universita di Roma ' ' La Sapienza' ' , Dipartimento di Ingegneria Strutturale e Geotecnica, via Eudossiana 18, I-00184 Roma (Italy)
2004-12-01
A one-dimensional model of plane circular arches with rigid sections is introduced. Suitable strain measures are defined as deviations from rigid displacements. If the arch is thin, constitutive arguments make the shearing strain negligible. Hence, the shearing indeformability will be assumed as inner constraint. By means of a formal power series expansion of the exact measures of deformation it is shown that the shearing indeformability implies some constraints on the axial strain. In particular, the first-order axial strain must vanish in the case of infinitesimal displacements. The same procedure is applied to pure flexible arches, in order to compare the two sets of results. It is shown that the hypothesis of finite pure flexibility is not compatible with small deformations of the arch. An example is provided to evaluate the effects of the two constraints at the first non-linear step of the perturbation expansions. (orig.)
10. Exploring the Conformal Constraint Equations
Butscher, Adrian
One method of studying the asymptotic structure of spacetime is to apply Penrose's conformal rescaling technique. In this setting, the rescaled Einstein equations for the metric and the conformal factor in the unphysical spacetime degenerate where the conformal factor vanishes, namely at the boundary representing null infinity. This problem can be avoided by means of a technique of H. Friedrich, which replaces the Einstein equations in the unphysical spacetime by an equivalent system of equations which is regular at the boundary. The initial value problem for these equations produces a system of constraint equations known as the conformal constraint equations. This work describes some of the properties of the conformal constraint equations and develops a perturbative method of generating solutions near Euclidean space under certain simplifying assumptions.
Constraints of noncommutativity from Astrophysical studies
Garcia-Aspeitia, Miguel A; Ortiz, C; Hinojosa-Ruiz, Sinhue; Rodriguez-Meza, Mario A
2015-01-01
This paper is devoted to study the astrophysical consequences of noncommutativity, focusing in stellar dynamics and rotational curves of galaxies. We start exploring a star filled with an incompressible fluid and a noncommutative fluid under the Tolman-Oppenheimer-Volkoff background. We analyze the effective pressure and mass, resulting in a constraint for the noncommutative parameter. Also we explore the rotation curves of galaxies assuming that the dark matter halo is a noncommutative fluid, obtaining an average value of the noncommutative parameter through an analysis of twelve LSB galaxies; our results are compared with traditional models like Pseudoisothermal, Navarro-Frenk-White and Burkert. As a final remark, we summarize our results as: $\\sqrt{\\theta}>0.075R$, from star constraints which is strong dependent of the stellar radius and $\\langle\\sqrt{\\theta}\\rangle\\simeq2.666\\rm kpc$ with standard deviation $\\sigma\\simeq1.090\\rm kpc$ from the galactic constraints.
Parametric constraints in multi-beam interference
Burrow, Guy M.; Gaylord, Thomas K.
2012-10-01
Multi-beam interference (MBI) represents a method of producing one-, two-, and three-dimensional submicron periodic optical-intensity distributions for applications including micro- and nano-electronics, photonic crystals, metamaterial, biomedical structures, optical trapping, and numerous other subwavelength structures. Accordingly, numerous optical configurations have been developed to implement MBI. However, these configurations typically provide limited ability to condition the key parameters of each interfering beam. Constraints on individual beam amplitudes and polarizations are systematically considered to understand their effects on lithographically useful MBI periodic patterning possibilities. A method for analyzing parametric constraints is presented and used to compare the optimized optical-intensity distributions for representative constrained systems. Case studies are presented for both square and hexagonal-lattices produced via three-beam interference. Results demonstrate that constraints on individual-beam polarizations significantly impact patterning possibilities and must be included in the systematic design of an MBI system.
Approximation for Maximum Surjective Constraint Satisfaction Problems
Bach, Walter
2011-01-01
Maximum surjective constraint satisfaction problems (Max-Sur-CSPs) are computational problems where we are given a set of variables denoting values from a finite domain B and a set of constraints on the variables. A solution to such a problem is a surjective mapping from the set of variables to B such that the number of satisfied constraints is maximized. We study the approximation performance that can be acccchieved by algorithms for these problems, mainly by investigating their relation with Max-CSPs (which are the corresponding problems without the surjectivity requirement). Our work gives a complexity dichotomy for Max-Sur-CSP(B) between PTAS and APX-complete, under the assumption that there is a complexity dichotomy for Max-CSP(B) between PO and APX-complete, which has already been proved on the Boolean domain and 3-element domains.
Judgement of Design Scheme Based on Flexible Constraint in ICAD
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.
Updated galactic radio constraints on Dark Matter
Cirelli, Marco
2016-01-01
We perform a detailed analysis of the synchrotron signals produced by Dark Matter annihilations and decays. We consider different set-ups for the propagation of electrons and positrons, the galactic magnetic field and Dark Matter properties. We then confront these signals with radio and microwave maps, including Planck measurements, from a frequency of 22 MHz up to 70 GHz. We derive two sets of constraints: conservative and progressive, the latter based on a modeling of the astrophysical emission. Radio and microwave constraints are complementary to those obtained with other indirect detection methods, especially for dark matter annihilating into leptonic channels.
On Matrix Representations of Participation Constraints
Hartmann, Sven; Leck, Uwe; Link, Sebastian
We discuss the existence of matrix representations for generalised and minimum participation constraints which are frequently used in database design and conceptual modelling. Matrix representations, also known as Armstrong relations, have been studied in literature e.g. for functional dependencies and play an important role in example-based design and for the implication problem of database constraints. The major tool to achieve the results in this paper is a theorem of Hajnal and Szemerédi on the occurrence of clique graphs in a given graph.
Simplification of integrity constraints for data integration
Christiansen, Henning; Martinenghi, Davide
2004-01-01
When two or more databases are combined into a global one, integrity may be violated even when each database is consistent with its own local integrity constraints. Efficient methods for checking global integrity in data integration systems are called for: answers to queries can then be trusted...... together with given a priori constraints on the combination, so that only a minimal number of tuples needs to be considered. Combination from scratch, integration of a new source, and absorption of local updates are dealt with for both the local-as-view and global-as-view approaches to data integration....
Universal constraints on axions from inflation
Ferreira, R. Z.; Sloth, M. S.
2014-01-01
perturbations through this mechanism, larger than the vacuum ones, without violating the observational constraints unless we combine this mechanism with a curvaton or if the sigma field becomes heavy and decays during inflation. Even in this last case there are non-trivial constraints coming from the slow......-roll evolution of the curvature perturbation on super horizon scales which should be taken into account. We also comment on implications for inflationary models where axions play an important role as, for example, models of natural inflation where more than one axion are included and models where the curvaton is...
Lagrange's principle in extremum problems with constraints
In this paper a general result concerning Lagrange's principle for so-called smoothly approximately convex problems is proved which encompasses necessary extremum conditions for mathematical and convex programming, the calculus of variations, Lyapunov problems, and optimal control problems with phase constraints. The problem of local controllability for a dynamical system with phase constraints is also considered. In an appendix, results are presented that relate to the development of a 'Lagrangian approach' to problems where regularity is absent and classical approaches are meaningless. Bibliography: 33 titles
Constraints on extra dimensions from atomic spectroscopy
Dahia, F
2015-01-01
We consider a hydrogen atom confined in a thick brane embedded in a higher-dimensional space. Due to effects of the extra dimensions, the gravitational potential is amplified in distances smaller than the size of the supplementary space, in comparison with the Newtonian potential. Studying the influence of the gravitational interaction modified by the extra dimensions on the energy levels of the hydrogen atom, we find independent constraints for the higher-dimensional Planck mass in terms of the thickness of the brane by using accurate measurements of atomic transition frequencies. The constraints are very stringent for narrow branes.
Quantum coding theory with realistic physical constraints
Yoshida, Beni
2010-01-01
The following open problems, which concern a fundamental limit on coding properties of quantum codes with realistic physical constraints, are analyzed and partially answered here: (a) the upper bound on code distances of quantum error-correcting codes with geometrically local generators, (b) the feasibility of a self-correcting quantum memory. To investigate these problems, we study stabilizer codes supported by local interaction terms with translation and scale symmetries on a $D$-dimensional lattice. Our analysis uses the notion of topology emerging in geometric shapes of logical operators, which sheds a surprising new light on theory of quantum codes with physical constraints.
An Intelligent MMRP Constraint Programming System
ZHENG Yujun; WANG kan; YANG Junwei
2006-01-01
In this paper, an intelligent constraint programming system for manufacturing material resource planning (MMRP) was presented. It is aimed to tackling large, particularly combinatorial, problems during the MMRP process, which increasingly involves complex sets of objectives and constraints in today's industrial manufacturing. The system consists of a domain-specific architecture, an algorithm library, and a pre-defined solution library, based on which intelligent agents can efficiently construct MMRP problem specifications, select suitable algorithms to solve problems, and evolve a population of solutions towards a Pareto-optimal frontier. Our system significantly improves the efficiency, effectiveness, and reliability of MMRP problem solving.
Spin constraints on nuclear energy density functionals
Robledo, L. M.; Bernard, R. N.; Bertsch, G. F.
2013-01-01
The Gallagher-Moszkowski rule in the spectroscopy of odd-odd nuclei imposes a new spin constraint on the energy functionals for self-consistent mean field theory. The commonly used parameterization of the effective three-body interaction in the Gogny and Skyrme families of energy functionals is ill-suited to satisfy the spin constraint. In particular, the Gogny parameterization of the three-body interaction has the opposite spin dependence to that required by the observed spectra. The two-bod...
Constraints on hadronically decaying dark matter
Garny, Mathias [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ibarra, Alejandro [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Tran, David [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Minnesota Univ., Minneapolis, MN (United States). School of Physics and Astronomy
2012-05-15
We present general constraints on dark matter stability in hadronic decay channels derived from measurements of cosmic-ray antiprotons.We analyze various hadronic decay modes in a model-independent manner by examining the lowest-order decays allowed by gauge and Lorentz invariance for scalar and fermionic dark matter particles and present the corresponding lower bounds on the partial decay lifetimes in those channels. We also investigate the complementarity between hadronic and gamma-ray constraints derived from searches for monochromatic lines in the sky, which can be produced at the quantum level if the dark matter decays into quark-antiquark pairs at leading order.
Constraints on hadronically decaying dark matter
We present general constraints on dark matter stability in hadronic decay channels derived from measurements of cosmic-ray antiprotons. We analyze various hadronic decay modes in a model-independent manner by examining the lowest-order decays allowed by gauge and Lorentz invariance for scalar and fermionic dark matter particles and present the corresponding lower bounds on the partial decay lifetimes in those channels. We also investigate the complementarity between hadronic and gamma-ray constraints derived from searches for monochromatic lines in the sky, which can be produced at the quantum level if the dark matter decays into quark-antiquark pairs at leading order
Constraint-based pattern mining in multi-relational databases
Nijssen, Siegfried; Jimenez, Aida; Guns, Tias
2011-01-01
We propose a new framework for constraint-based pattern mining in multi-relational databases. Distinguishing features of the framework are that (1) it allows finding patterns not only under anti-monotonic constraints, but also under monotonic constraints and closedness constraints, among others, expressed over complex aggregates over multiple relations; (2) it builds on a declarative graphical representation of constraints that links closely to data models of multi-relational databases and co...
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. copyright 1997 The American Physical Society
Capacity constraints and the inevitability of mediators in adword auctions
Singh, Sudhir Kumar; Gunadhi, Himawan; Rezaei, Behnam A
2007-01-01
One natural constraint in the sponsored search advertising framework arises from the fact that there is a limit on the number of available slots, especially for the popular keywords, and as a result, a significant pool of advertisers are left out. We study the emergence of diversification in the adword market triggered by such capacity constraints in the sense that new market mechanisms, as well as, new for-profit agents are likely to emerge to combat or to make profit from the opportunities created by shortages in ad-space inventory. We propose a model where the additional capacity is provided by for-profit agents (or, mediators), who compete for slots in the original auction, draw traffic, and run their own sub-auctions. The quality of the additional capacity provided by a mediator is measured by its {\\it fitness} factor. We compute revenues and payoffs for all the different parties at a {\\it symmetric Nash equilibrium} (SNE) when the mediator-based model is operated by a mechanism currently being used by G...
Preconditioning for partial differential equation constrained optimization with control constraints
Stoll, Martin
2011-10-18
Optimal control problems with partial differential equations play an important role in many applications. The inclusion of bound constraints for the control poses a significant additional challenge for optimization methods. In this paper, we propose preconditioners for the saddle point problems that arise when a primal-dual active set method is used. We also show for this method that the same saddle point system can be derived when the method is considered as a semismooth Newton method. In addition, the projected gradient method can be employed to solve optimization problems with simple bounds, and we discuss the efficient solution of the linear systems in question. In the case when an acceleration technique is employed for the projected gradient method, this again yields a semismooth Newton method that is equivalent to the primal-dual active set method. We also consider the Moreau-Yosida regularization method for control constraints and efficient preconditioners for this technique. Numerical results illustrate the competitiveness of these approaches. © 2011 John Wiley & Sons, Ltd.
On controllability of neuronal networks with constraints on the average of control gains.
Tang, Yang; Wang, Zidong; Gao, Huijun; Qiao, Hong; Kurths, Jürgen
2014-12-01
Control gains play an important role in the control of a natural or a technical system since they reflect how much resource is required to optimize a certain control objective. This paper is concerned with the controllability of neuronal networks with constraints on the average value of the control gains injected in driver nodes, which are in accordance with engineering and biological backgrounds. In order to deal with the constraints on control gains, the controllability problem is transformed into a constrained optimization problem (COP). The introduction of the constraints on the control gains unavoidably leads to substantial difficulty in finding feasible as well as refining solutions. As such, a modified dynamic hybrid framework (MDyHF) is developed to solve this COP, based on an adaptive differential evolution and the concept of Pareto dominance. By comparing with statistical methods and several recently reported constrained optimization evolutionary algorithms (COEAs), we show that our proposed MDyHF is competitive and promising in studying the controllability of neuronal networks. Based on the MDyHF, we proceed to show the controlling regions under different levels of constraints. It is revealed that we should allocate the control gains economically when strong constraints are considered. In addition, it is found that as the constraints become more restrictive, the driver nodes are more likely to be selected from the nodes with a large degree. The results and methods presented in this paper will provide useful insights into developing new techniques to control a realistic complex network efficiently. PMID:24733036
Nonparametric instrumental regression with non-convex constraints
Grasmair, M.; Scherzer, O.; Vanhems, A.
2013-03-01
This paper considers the nonparametric regression model with an additive error that is dependent on the explanatory variables. As is common in empirical studies in epidemiology and economics, it also supposes that valid instrumental variables are observed. A classical example in microeconomics considers the consumer demand function as a function of the price of goods and the income, both variables often considered as endogenous. In this framework, the economic theory also imposes shape restrictions on the demand function, such as integrability conditions. Motivated by this illustration in microeconomics, we study an estimator of a nonparametric constrained regression function using instrumental variables by means of Tikhonov regularization. We derive rates of convergence for the regularized model both in a deterministic and stochastic setting under the assumption that the true regression function satisfies a projected source condition including, because of the non-convexity of the imposed constraints, an additional smallness condition.
Nonparametric instrumental regression with non-convex constraints
This paper considers the nonparametric regression model with an additive error that is dependent on the explanatory variables. As is common in empirical studies in epidemiology and economics, it also supposes that valid instrumental variables are observed. A classical example in microeconomics considers the consumer demand function as a function of the price of goods and the income, both variables often considered as endogenous. In this framework, the economic theory also imposes shape restrictions on the demand function, such as integrability conditions. Motivated by this illustration in microeconomics, we study an estimator of a nonparametric constrained regression function using instrumental variables by means of Tikhonov regularization. We derive rates of convergence for the regularized model both in a deterministic and stochastic setting under the assumption that the true regression function satisfies a projected source condition including, because of the non-convexity of the imposed constraints, an additional smallness condition. (paper)
Varying Constants: Constraints from Seasonal Variations
Shaw, Douglas J
2010-01-01
We analyse the constraints obtained from new atomic clock data on the possible time variation of the fine structure `constant' and the electron-proton mass ratio and show how they are strengthened when the seasonal variation of Sun's gravitational field at the Earth's surface is taken into account.
On the canonical treatment of Lagrangian constraints
The canonical treatment of dynamic systems with manifest Lagrangian constraints proposed by Berezin is applied to concrete examples: a special Lagrangian linear in velocities, relativistic particles in proper time gauge, a relativistic string in orthonormal gauge, and the Maxwell field in the Lorentz gauge
Free material opimization: towards the stress constraints
Kočvara, Michal; Stingl, M.
Vol. 5(1). Zurich: EMS Publishing House, 2008 - (Kunish, K.; Leugering, G.; Sprekels, J.; Troltzsch, F.), s. 620-621 ISSN 1660-8933. [ Optimal control of Coupled Systems of PDE. Oberwolfach (DE), 02.03.2008-08.03.2008] Institutional research plan: CEZ:AV0Z10750506 Keywords : free material optimization * stress constraints Subject RIV: BA - General Mathematics
Effective direct and indirect top constraints
We use an effective field theory approach to study in a systematic way the effects of anomalous top couplings. We focus in particular on CP-violating operators and find constraints on them from direct and indirect measurements. This has important implications for new physics models and the search for their signatures at the LHC.
Ability or Finances as Constraints on Entrepreneurship?
Andersen, Steffen; Meisner Nielsen, Kasper
We use a natural experiment in Denmark to test the hypothesis that aspiring entrepreneurs face financial constraints because of low entrepreneurial quality. We identify 304 constrained entrepreneurs who start a business after receiving windfall wealth and examine the performance of these marginal...
Ability or Finances as Constraints on Entrepreneurship?
Andersen, Steffen; Meisner Nielsen, Kasper
2012-01-01
We use a natural experiment in Denmark to test the hypothesis that aspiring entrepreneurs face financial constraints because of low entrepreneurial quality. We identify 304 constrained entrepreneurs who start a business after receiving windfall wealth and examine the performance of these marginal...
CMB Constraints on Cosmic Strings and Superstrings
Charnock, Tom; Copeland, Edmund J; Moss, Adam
2016-01-01
We present the first complete MCMC analysis of cosmological models with evolving cosmic (super)string networks, using the Unconnected Segment Model in the unequal-time correlator formalism. For ordinary cosmic string networks, we derive joint constraints on {\\Lambda}CDM and string network parameters, namely the string tension G{\\mu}, the loop-chopping efficiency c_r and the string wiggliness {\\alpha}. For cosmic superstrings, we obtain joint constraints on the fundamental string tension G{\\mu}_F, the string coupling g_s, the self-interaction coefficient c_s, and the volume of compact extra dimensions w. This constitutes the most comprehensive CMB analysis of {\\Lambda}CDM cosmology + strings to date. For ordinary cosmic string networks our updated constraint on the string tension is, in relativistic units, G{\\mu}<1.1x10^-7, while for cosmic superstrings our constraint on the fundamental string tension is G{\\mu}_F<2.8x10^-8, both obtained using Planck2015 temperature and polarisation data.
Dynamic System Adaptation by Constraint Orchestration
Groenewegen, L P J
2008-01-01
For Paradigm models, evolution is just-in-time specified coordination conducted by a special reusable component McPal. Evolution can be treated consistently and on-the-fly through Paradigm's constraint orchestration, also for originally unforeseen evolution. UML-like diagrams visually supplement such migration, as is illustrated for the case of a critical section solution evolving into a pipeline architecture.
Confluence Modulo Equivalence in Constraint Handling Rules
Christiansen, Henning; Kirkeby, Maja Hanne
2014-01-01
Previous results on confluence for Constraint Handling Rules, CHR, are generalized to take into account user-defined state equivalence relations. This allows a much larger class of programs to enjoy the ad- vantages of confluence, which include various optimization techniques and simplified corre...
CULTURAL CONSTRAINTS ON INNOVATION-BASED GROWTH
Klasing, Mariko J.; Milionis, Petros
2014-01-01
To what extent does the cultural composition of a society impose a constraint on its long-run growth potential? We study this question in the context of an innovation-based model of growth where cultural attitudes are endogenously transmitted from one generation to the next. Focusing on attitudes re
CMB constraints on cosmic strings and superstrings
Charnock, Tom; Avgoustidis, Anastasios; Copeland, Edmund J.; Moss, Adam
2016-06-01
We present the first complete Markov chain Monte Carlo analysis of cosmological models with evolving cosmic (super)string networks, using the unconnected segment model in the unequal-time correlator formalism. For ordinary cosmic string networks, we derive joint constraints on Λ cold dark matter (CDM) and string network parameters, namely the string tension G μ , the loop-chopping efficiency cr, and the string wiggliness α . For cosmic superstrings, we obtain joint constraints on the fundamental string tension G μF, the string coupling gs, the self-interaction coefficient cs, and the volume of compact extra dimensions w . This constitutes the most comprehensive CMB analysis of Λ CDM cosmology+strings to date. For ordinary cosmic string networks our updated constraint on the string tension, obtained using Planck2015 temperature and polarization data, is G μ <1.1 ×10-7 in relativistic units, while for cosmic superstrings our constraint on the fundamental string tension after marginalizing over gs, cs, and w is G μF<2.8 ×10-8.
Constraint analysis for variational discrete systems
A canonical formalism and constraint analysis for discrete systems subject to a variational action principle are devised. The formalism is equivalent to the covariant formulation, encompasses global and local discrete time evolution moves and naturally incorporates both constant and evolving phase spaces, the latter of which is necessary for a time varying discretization. The different roles of constraints in the discrete and the conditions under which they are first or second class and/or symmetry generators are clarified. The (non-) preservation of constraints and the symplectic structure is discussed; on evolving phase spaces the number of constraints at a fixed time step depends on the initial and final time step of evolution. Moreover, the definition of observables and a reduced phase space is provided; again, on evolving phase spaces the notion of an observable as a propagating degree of freedom requires specification of an initial and final step and crucially depends on this choice, in contrast to the continuum. However, upon restriction to translation invariant systems, one regains the usual time step independence of canonical concepts. This analysis applies, e.g., to discrete mechanics, lattice field theory, quantum gravity models, and numerical analysis
Confluence Modulo Equivalence in Constraint Handling Rules
Christiansen, Henning; Kirkeby, Maja Hanne
2015-01-01
Previous results on confluence for Constraint Handling Rules, CHR, are generalized to take into account user-defined state equivalence relations. This allows a much larger class of programs to enjoy the advantages of confluence, which include various optimization techniques and simplified...
Identifying and reducing constraints to potato productivity
Potato yield in Maine has remained relatively constant for over 50 years, despite increased inputs of pesticides, nutrients, and water. Research is needed to identify and reduce the constraints to potato productivity. We evaluated Status Quo, Soil Conserving, Soil Improving, and Disease Suppressive ...
Ability or Finances as Constraints to Entrepreneurship?
Andersen, Steffen; Meisner Nielsen, Kasper
This study exploits a natural experiment to investigate why financial constraints appear to limit firm formation. Exogenous variation in wealth results from unexpected inheritance due to sudden death and allows us to identify 304 constrained entrepreneurs, who start a business after receiving win...
The Ambiguous Role of Constraints in Creativity
Biskjær, Michael Mose; Onarheim, Balder; Wiltschnig, Stefan
2011-01-01
case studies of Danish cutting-edge proponents of creative expertise thus exemplifying each domain, this preliminary exploration mainly focuses on similarities in how such successful professionals work with constraints to frame their creative process and ensure its progression toward the final outcome...
Cognitive Dissonance Reduction as Constraint Satisfaction.
Shultz, Thomas R.; Lepper, Mark R.
1996-01-01
It is argued that the reduction of cognitive dissonance can be viewed as a constraint satisfaction problem, and a computational model of the process of consonance seeking is proposed. Simulations from this model matched psychological findings from the insufficient justification and free-choice paradigms of cognitive dissonance theory. (SLD)
Manufacturability analysis to combine additive and subtractive processes
Kerbrat, Olivier; Mognol, Pascal; Hascoët, Jean-Yves
2010-01-01
International audience Purpose - The purpose of this paper is to propose a methodology to estimate manufacturing complexity for both machining and layered manufacturing. The goal is to take into account manufacturing constraints at design stage in order to realize tools (dies and molds) by a combination of a subtractive process (high-speed machining) and an additive process (selective laser sintering). Design/methodology/approach - Manufacturability indexes are defined and calculated from ...
The Time-Course of Morphological Constraints: Evidence from Eye-Movements during Reading
Cunnings, Ian; Clahsen, Harald
2007-01-01
Lexical compounds in English are constrained in that the non-head noun can be an irregular but not a regular plural (e.g. mice eater vs. *rats eater), a contrast that has been argued to derive from a morphological constraint on modifiers inside compounds. In addition, bare nouns are preferred over plural forms inside compounds (e.g. mouse eater…
Formation control of marine craft using constraint functions
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......, constraint forces arise. Since the constraint functions are designed for a desired effect, the forces can be seen as control laws. These forces act so that the constraint functions are satisfied in order to keep the formation assembled during operations. Examples of constraint functions that can be used to...
Importance of parametrizing constraints in quantum-mechanical variational calculations
Chung, Kwong T.; Bhatia, A. K.
1992-01-01
In variational calculations of quantum mechanics, constraints are sometimes imposed explicitly on the wave function. These constraints, which are deduced by physical arguments, are often not uniquely defined. In this work, the advantage of parametrizing constraints and letting the variational principle determine the best possible constraint for the problem is pointed out. Examples are carried out to show the surprising effectiveness of the variational method if constraints are parameterized. It is also shown that misleading results may be obtained if a constraint is not parameterized.
Medical image segmentation by means of constraint satisfaction neural network
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
Overhead in communication systems as the cost of constraints
Dunn, Brian P.
This dissertation develops a perspective for studying overhead in communication systems that contrasts the traditional viewpoint that overhead is the "non-data" portion of transmissions. By viewing overhead as the cost of constraints imposed on a system, information-theoretic techniques can be used to obtain fundamental limits on system performance. In principle, protocol overhead in practical implementations can then be benchmarked against these fundamental limits in order to identify opportunities for improvement. We examine three sources of overhead that have been studied in both information theory and networking using different models and metrics. For multi-access communication systems, we compute constrained capacity regions for two binary additive channels with feedback and develop inner and outer bounds on the capacity region of the packet collision channel with feedback that appear to be tight numerically. We develop bounds on the protocol overhead required to meet an average delay constraint and then use these bounds to characterize rate-delay tradeoffs for communicating a bursty source over a noisy channel. Finally, we study information-theoretic security in timing channels and show that non-zero secrecy rates can be achieved over the wiretap timing channel using a deterministic encoder.
Planck intermediate results. XXIV. Constraints on variation of fundamental constants
Ade, P A R; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Battaner, E.; Benabed, K.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bielewicz, P.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Burigana, C.; Butler, R.C.; Calabrese, E.; Chamballu, A.; Chiang, H.C.; Christensen, P.R.; Clements, D.L.; Colombo, L.P.L.; Couchot, F.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Diego, J.M.; Dole, H.; Dore, O.; Dupac, X.; Ensslin, T.A.; Eriksen, H.K.; Fabre, O.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gregorio, A.; Gruppuso, A.; Hansen, F.K.; Hanson, D.; Harrison, D.L.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Jaffe, A.H.; Jones, W.C.; Keihanen, E.; Keskitalo, R.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lamarre, J.M.; Lasenby, A.; Lawrence, C.R.; Leonardi, R.; Lesgourgues, J.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Mandolesi, N.; Maris, M.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Meinhold, P.R.; Melchiorri, A.; Mendes, L.; Menegoni, E.; Mennella, A.; Migliaccio, M.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Moss, A.; Munshi, D.; Murphy, J.A.; Naselsky, P.; Nati, F.; Natoli, P.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C.A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Pratt, G.W.; Prunet, S.; Rachen, J.P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Ristorcelli, I.; Rocha, G.; Roudier, G.; Rusholme, B.; Sandri, M.; Savini, G.; Scott, D.; Spencer, L.D.; Stolyarov, V.; Sudiwala, R.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Uzan, J.P.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L.A.; Yvon, D.; Zacchei, A.; Zonca, A.
2015-01-01
Any variation of the fundamental physical constants, and more particularly of the fine structure constant, $\\alpha$, or of the mass of the electron, $m_e$, would affect the recombination history of the Universe and cause an imprint on the cosmic microwave background angular power spectra. We show that the Planck data allow one to improve the constraint on the time variation of the fine structure constant at redshift $z\\sim 10^3$ by about a factor of 5 compared to WMAP data, as well as to break the degeneracy with the Hubble constant, $H_0$. In addition to $\\alpha$, we can set a constraint on the variation of the mass of the electron, $m_{\\rm e}$, and on the simultaneous variation of the two constants. We examine in detail the degeneracies between fundamental constants and the cosmological parameters, in order to compare the limits obtained from Planck and WMAP and to determine the constraining power gained by including other cosmological probes. We conclude that independent time variations of the fine structu...
Resolving mobility constraints impeding rural seniors' access to regionalized services.
Ryser, Laura; Halseth, Greg
2012-01-01
Rural and small town places in developed economies are aging. While attention has been paid to the local transportation needs of rural seniors, fewer researchers have explored their regional transportation needs. This is important given policies that have reduced and regionalized many services and supports. This article explores mobility constraints impeding rural seniors' access to regionalized services using the example of northern British Columbia. Drawing upon several qualitative studies, we explore geographical, maintenance, organizational, communication, human resources, infrastructure, and financial constraints that affect seniors' regional mobility. Our findings indicate that greater coordination across multiple government agencies and jurisdictions is needed and more supportive policies and resources must be in place to facilitate a comprehensive regional transportation strategy. In addition to discussing the complexities of these geographies, the article identifies innovative solutions that have been deployed in northern British Columbia to support an aging population. This research provides a foundation for developing a comprehensive understanding of the key issues that need to be addressed to inform strategic investments in infrastructure and programs that support the regional mobility and, hence, healthy aging of rural seniors. PMID:22720890
Evidence-based history taking under "time constraint"
Alireza Moayyeri
2011-01-01
Full Text Available Physicians all through the world visit patients under time limitations. The most important troubled clinical skill under "time constraint" is the diagnostic approach. In this situation, clinicians need some diagnostic approaches to reduce both diagnostic time and errors. It seems that highly experienced physicians utilize some special tactics in this regard. Evidence-based medicine (EBM as a relatively new paradigm for clinical practice stresses on using research evidences in diagnostic evaluations. The authors aimed to evaluate experts′ strategies and assess what EBM can add to these tactics. They reviewed diagnostic strategies of some veteran internists in their busy outpatient clinics and proposed an evidence-based diagnostic model engaging clinical experience and research evidence. It appears that every clinician utilizes a set of "key pointer" questions for decision-making. In addition to use of evidence-based resources for making differential diagnosis and estimating utility of various diseases, clinicians should use "key pointers" with significant likelihood ratios and from independent systems to reduce time and errors of history taking. Clinical trainees can improve their practice by constructing their own set of pointers from valid research evidences. Using this diagnostic model, EBM can help physicians to struggle against their "time constraint".
Degree heterogeneity in spatial networks with total cost constraint
Liu, Weiping; Zhou, Yanbo
2011-01-01
Recently, In [Phys. Rev. Lett. 104, 018701 (2010)] the authors studied a spatial network which is constructed from a regular lattice by adding long-range edges (shortcuts) with probability $P_{ij}\\sim r_{ij}^{-\\alpha}$, where $r_{ij}$ is the Manhattan length of the long-range edges. The total length of the additional edges is subject to a cost constraint ($\\sum r=C$). These networks have fixed optimal exponent $\\alpha$ for transportation (measured by the average shortest-path length). However, we observe that the degree in such spatial networks is homogenously distributed, which is far different from real networks such as airline systems. In this paper, we propose a method to introduce degree heterogeneity in spatial networks with total cost constraint. Results show that with degree heterogeneity the optimal exponent shifts to a smaller value and the average shortest-path length can further decrease. Moreover, we consider the synchronization on the spatial networks and related results are discussed. Our new m...
Locality constraints and 2D quasicrystals
The plausible assumption that long-range interactions between atoms are negligible in a quasicrystal leaks to the study of tilings that obey constraints on the local configurations of tiles. The theory of such constraints (called matching rules) for 2D quasicrystal tilings is reviewed here. Different types of matching rules are defined and examples of tilings obeying them are given where known. The role of tile decoration is discussed and is shown to be significant in at least two cases (octagonal and dodecagonal duals of periodic 4-grids and 6-grids). A new result is introduced: a constructive procedure is described for generating weak matching rules for tilings with N-fold symmetry, for any N that is either a prime number or twice a prime number. The physics associated with weak matching rules, results on local growth rules, and the case of icosahedral symmetry are all briefly discussed. (author). 29 refs, 4 figs
Cluster constraints on f(R) gravity
Modified gravitational forces in models that seek to explain cosmic acceleration without dark energy typically predict deviations in the abundance of massive dark matter halos. We conduct the first, simulation calibrated, cluster abundance constraints on a modified gravity model, specifically the modified action f(R) model. The local cluster abundance, when combined with geometric and high redshift data from the cosmic microwave background, supernovae, H0, and baryon acoustic oscillations, improves previous constraints by nearly 4 orders of magnitude in the field amplitude. These limits correspond to a 2 order of magnitude improvement in the bounds on the range of the force modification from the several Gpc scale to the tens of Mpc scale.
Cluster Constraints on f(R) Gravity
Schmidt, Fabian; Hu, Wayne
2009-01-01
Modified gravitational forces in models that seek to explain cosmic acceleration without dark energy typically predict deviations in the abundance of massive dark matter halos. We conduct the first, simulation calibrated, cluster abundance constraints on a modified gravity model, specifically the modified action f(R) model. The local cluster abundance, when combined with geometric and high redshift data from the cosmic microwave background, supernovae, H_0 and baryon acoustic oscillations, improve previous constraints by nearly 4 orders of magnitude in the field amplitude. These limits correspond to a 2 order of magnitude improvement in the bounds on the range of the force modification from the several Gpc scale to the tens of Mpc scale.
Modeling Regular Replacement for String Constraint Solving
Fu, Xiang; Li, Chung-Chih
2010-01-01
Bugs in user input sanitation of software systems often lead to vulnerabilities. Among them many are caused by improper use of regular replacement. This paper presents a precise modeling of various semantics of regular substitution, such as the declarative, finite, greedy, and reluctant, using finite state transducers (FST). By projecting an FST to its input/output tapes, we are able to solve atomic string constraints, which can be applied to both the forward and backward image computation in model checking and symbolic execution of text processing programs. We report several interesting discoveries, e.g., certain fragments of the general problem can be handled using less expressive deterministic FST. A compact representation of FST is implemented in SUSHI, a string constraint solver. It is applied to detecting vulnerabilities in web applications
Parsing of Spoken Language under Time Constraints
Menzel, W
1994-01-01
Spoken language applications in natural dialogue settings place serious requirements on the choice of processing architecture. Especially under adverse phonetic and acoustic conditions parsing procedures have to be developed which do not only analyse the incoming speech in a time-synchroneous and incremental manner, but which are able to schedule their resources according to the varying conditions of the recognition process. Depending on the actual degree of local ambiguity the parser has to select among the available constraints in order to narrow down the search space with as little effort as possible. A parsing approach based on constraint satisfaction techniques is discussed. It provides important characteristics of the desired real-time behaviour and attempts to mimic some of the attention focussing capabilities of the human speech comprehension mechanism.
Curvature constraints from Large Scale Structure
Di Dio, Enea; Raccanelli, Alvise; Durrer, Ruth; Kamionkowski, Marc; Lesgourgues, Julien
2016-01-01
We modified the CLASS code in order to include relativistic galaxy number counts in spatially curved geometries; we present the formalism and study the effect of relativistic corrections on spatial curvature. The new version of the code is now publicly available. Using a Fisher matrix analysis, we investigate how measurements of the spatial curvature parameter $\\Omega_K$ with future galaxy surveys are affected by relativistic effects, which influence observations of the large scale galaxy distribution. These effects include contributions from cosmic magnification, Doppler terms and terms involving the gravitational potential. As an application, we consider angle and redshift dependent power spectra, which are especially well suited for model independent cosmological constraints. We compute our results for a representative deep, wide and spectroscopic survey, and our results show the impact of relativistic corrections on the spatial curvature parameter estimation. We show that constraints on the curvature para...
Cosmological constraints on the neutron lifetime
Salvati, L.; Pagano, L.; Consiglio, R.; Melchiorri, A.
2016-03-01
We derive new constraints on the neutron lifetime based on the recent Planck 2015 observations of temperature and polarization anisotropies of the CMB. Under the assumption of standard Big Bang Nucleosynthesis, we show that Planck data constrains the neutron lifetime to τn = (907±69) [s] at 68% c.l.. Moreover, by including the direct measurements of primordial Helium abundance of Aver et al. (2015) and Izotov et al. (2014), we show that cosmological data provide the stringent constraints τn = (875±19) [s] and τn = (921±11) [s] respectively. The latter appears to be in tension with neutron lifetime value quoted by the Particle Data Group (τn = (880.3±1.1) [s]). Future CMB surveys as COrE+, in combination with a weak lensing survey as EUCLID, could constrain the neutron lifetime up to a ~ 6 [s] precision.
Decoupling Coupled Constraints Through Utility Design
Li, N; Marden, JR
2014-08-01
Several multiagent systems exemplify the need for establishing distributed control laws that ensure the resulting agents' collective behavior satisfies a given coupled constraint. This technical note focuses on the design of such control laws through a game-theoretic framework. In particular, this technical note provides two systematic methodologies for the design of local agent objective functions that guarantee all resulting Nash equilibria optimize the system level objective while also satisfying a given coupled constraint. Furthermore, the designed local agent objective functions fit into the framework of state based potential games. Consequently, one can appeal to existing results in game-theoretic learning to derive a distributed process that guarantees the agents will reach such an equilibrium.
On Simplification of Database Integrity Constraints
Christiansen, Henning; Martinenghi, Davide
2006-01-01
on transformation operators that apply to integrity constraints written in a rich DATALOG-like language with negation. The resulting procedure produces, at design-time, simplified constraints for parametric transaction patterns, which can then be instantiated and checked for consistency at run-time. These tests......Without proper simplification techniques, database integrity checking can be prohibitively time consuming. Several methods have been developed for producing simplified incremental checks for each update but none until now of sufficient quality and generality for providing a true practical impact...... is strictly related to query containment; in fact, an ideal simplification procedure can only exist in database languages for which query containment is decidable. However, simplifications that do not qualify as ideal may also be relevant for practical purposes. We present a concrete approach based...
An Approach of Degree Constraint MST Algorithm
Sanjay Kumar Pal
2013-08-01
Full Text Available This paper is approaching a new technique of creating Minimal Spanning Trees based on degree constraints of a simple symmetric and connected graph G. Here we recommend a new algorithm based on the average degree sequence factor of the nodes in the graph. The time complexity of the problem is less than O(N log|E| compared to the other existing time complexity algorithms is O(|E| log|E|+C of Kruskal, which is optimum. The goal is to design an algorithm that is simple, graceful, resourceful, easy to understand, and applicable in various fields starting from constraint based network design, mobile computing to other field of science and engineering.
Synchronization of nonlinear systems under information constraints
Fradkov, Alexander L.; Andrievsky, Boris; Evans, Robin J.
2008-09-01
A brief survey of control and synchronization under information constraints (limited information capacity of the coupling channel) is given. Limit possibilities of nonlinear observer-based synchronization systems with first-order coders or full-order coders are considered in more detail. The existing and new theoretical results for multidimensional drive-response Lurie systems (linear part plus nonlinearity depending only on measurable outputs) are presented. It is shown that the upper bound of the limit synchronization error (LSE) is proportional to the upper bound of the transmission error. As a consequence, the upper and lower bounds of LSE are proportional to the maximum coupling signal rate and inversely proportional to the information transmission rate (channel capacity). The analysis is extended to networks having a "chain," "star," or "star-chain" topology. Adaptive chaotic synchronization under information constraints is analyzed. The results are illustrated by example: master-slave synchronization of two chaotic Chua systems coupled via a channel with limited capacity.
Universal growth constraints of human systems
Hébert-Dufresne, Laurent; Young, Jean-Gabriel; Dubé, Louis J
2013-01-01
Scale independence is a ubiquitous feature of complex systems which implies a highly skewed distribution of resources with no characteristic scale. Research has long focused on why systems as varied as protein networks, evolution and stock actions all feature scale independence. Assuming that they simply do, we focus here on describing exactly how this behavior emerges. We show that growing towards scale independence implies strict constraints: the first is the well-known preferential attachment principle and the second is a new form of temporal scaling. These constraints pave a precise evolution path, such that an instantaneous snapshot of a distribution is enough to reconstruct its past and to predict its future. We validate our approach on diverse spheres of human activities ranging from scientific and artistic productivity, to sexual relations and online traffic.
Constraints on Majorana Dark Matter from the LHC and IceCube
Heisig, Jan; Pellen, Mathieu; Wiebusch, Christopher
2015-01-01
We consider a simplified model for Majorana fermion dark matter and explore constraints from direct, indirect and LHC collider searches. The dark matter is assumed to couple to the Standard Model through a vector mediator with axial-vector interactions. We provide detailed analyses of LHC mono-jet searches and IceCube limits on dark matter annihilation in the Sun. We demonstrate that LHC and IceCube searches for Majorana dark matter are complementary and derive new limits on the dark matter and mediator masses, including in addition constraints from LHC di-jet searches, direct detection and the dark matter relic density.
Quark-Meson Coupling Model, Nuclear Matter Constraints and Neutron Star Properties
Whittenbury, D. L.; Carroll, J D; Thomas, A. W.; Tsushima, K; Stone, J. R.
2013-01-01
We explore the equation of state for nuclear matter in the quark-meson coupling model, including full Fock terms. The comparison with phenomenological constraints can be used to restrict the few additional parameters appearing in the Fock terms which are not present at Hartree level. Because the model is based upon the in-medium modification of the quark structure of the bound hadrons, it can be applied without additional parameters to include hyperons and to calculate the equation of state o...
Molnár, Botond; Ercsey-Ravasz, Mária
2013-01-01
There has been a long history of using neural networks for combinatorial optimization and constraint satisfaction problems. Symmetric Hopfield networks and similar approaches use steepest descent dynamics, and they always converge to the closest local minimum of the energy landscape. For finding global minima additional parameter-sensitive techniques are used, such as classical simulated annealing or the so-called chaotic simulated annealing, which induces chaotic dynamics by addition of extr...
Cosmological Constraints from Primordial Black Holes
Liddle, Andrew R.; Green, Anne M.
1998-01-01
Primordial black holes may form in the early Universe, for example from the collapse of large amplitude density perturbations predicted in some inflationary models. Light black holes undergo Hawking evaporation, the energy injection from which is constrained both at the epoch of nucleosynthesis and at the present. The failure as yet to unambiguously detect primordial black holes places important constraints. In this article, we are particularly concerned with the dependence of these constrain...
Liquidity constraints of the middle class
Campbell, J.R.; Hercowitz, Zvi
2009-01-01
Consumption of households with liquid financial assets responds much more to transitory income shocks than the permanent-income hypothesis predicts. That is, middle class households act as if they face liquidity constraints. This paper addresses this puzzling observation with a model of impatient households that face a large recurring expenditure. In spite of impatience, they save as this expenditure draws near. We call such saving made in preparation for a foreseeable event "term saving". Un...
06401 Abstracts Collection -- Complexity of Constraints
Creignou, Nadia; Kolaitis, Phokion; Vollmer, Heribert
2006-01-01
From 01.10.06 to 06.10.06, the Dagstuhl Seminar 06401 ``Complexity of Constraints'' was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topi...
Credit Constraints, Heterogeneous Firms, and International Trade
Kalina Manova
2008-01-01
This paper examines the detrimental consequences of financial market imperfections for international trade. I develop a heterogeneous-firm model with countries at different levels of financial development and sectors of varying financial vulnerability. Applying this model to aggregate trade data, I study the mechanisms through which credit constraints operate. First, financial development increases countries' exports above and beyond its impact on overall production. Firm selection into expor...
Astrophysical Constraints on Singlet Scalars at LHC
Hertzberg, Mark P.(Center for Theoretical Physics and Dept. of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA); Masoumi, Ali
2016-01-01
We consider the viability of new heavy gauge singlet scalar particles at the LHC. Our motivation for this study comes from the possibility of a new particle with mass ~ 750 GeV decaying significantly into two photons at LHC, but our analysis applies more broadly. We show that there are significant constraints from astrophysics and cosmology on the simplest UV complete models that incorporate such a particle and its associated collider signal. The simplest and most obvious UV complete model th...
Near-Optimal Fingerprinting with Constraints
Gulyas, Gabor Gyorgy; Acs, Gergely; Castelluccia, Claude
2016-01-01
International audience 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 depend on explicit constraints on the number of attributes learnable about individuals, i.e., the size of their fi...
Updated galactic radio constraints on Dark Matter
Cirelli, Marco; Taoso, Marco
2016-01-01
We perform a detailed analysis of the synchrotron signals produced by Dark Matter annihilations and decays. We consider different set-ups for the propagation of electrons and positrons, the galactic magnetic field and Dark Matter properties. We then confront these signals with radio and microwave maps, including Planck measurements, from a frequency of 22 MHz up to 70 GHz. We derive two sets of constraints: conservative and progressive, the latter based on a modeling of the astrophysical emis...
Constraint-Free Theories of Gravitation
Estabrook, Frank B.; Robinson, R. Steve; Wahlquist, Hugo D.
1998-01-01
Lovelock actions (more precisely, extended Gauss-Bonnet forms) when varied as Cartan forms on subspaces of higher dimensional flat Riemannian manifolds, generate well set, causal exterior differential systems. In particular, the Einstein- Hilbert action 4-form, varied on a 4 dimensional subspace of E(sub 10) yields a well set generalized theory of gravity having no constraints. Rcci-flat solutions are selected by initial conditions on a bounding 3-space.
WORK CONTINUITY CONSTRAINTS IN PROJECT SCHEDULING
Vanhoucke, M.
2004-01-01
Repetitive projects involve the repetition of activities along the stages of the project. Since the resources required to perform these activities move from one stage to the other, a main objective of scheduling these projects is to maintain the continuity of work of these resources so as to minimize the idle time of resources. This requirement, often referred to as work continuity constraints, involves a trade-off between total project duration and the resource idle time. The contribution of...
Varying Alpha: New Constraints from Seasonal Variations
Barrow, John D
2008-01-01
We analyze the constraints obtained from new atomic clock data on the possible time variation of the fine structure `constant' and the electron-proton mass ratio and show how they are strengthened when the seasonal variation of Sun's gravitational field at the Earth's surface is taken into account. We compare these bounds with those obtainable from tests of the Weak Equivalence Principle and high-redshift observations of quasar absorption spectra consistent with time variations in the fine structure constant.
A Constraints Driven Product Lifecycle Management Framework
LE DUIGOU, Julien; Bernard, Alain; Perry, Nicolas; Delplace, Jean-Charles
2009-01-01
The management of the product information during its lifecycle is a strategic issue for the industry. In this paper, a constraints driven framework is proposed to create and manage the product information. The method proposes to each actor that intervenes on the product life cycle to act on the quote, the development or the industrialisation of the product. From each phase of the product lifecycle, the extraction, capitalisation and reuse of fundamental knowledge is coordinated by...
Cluster Constraints on f(R) Gravity
Schmidt, Fabian; Vikhlinin, Alexey; Hu, Wayne
2009-01-01
Modified gravitational forces in models that seek to explain cosmic acceleration without dark energy typically predict deviations in the abundance of massive dark matter halos. We conduct the first, simulation calibrated, cluster abundance constraints on a modified gravity model, specifically the modified action f(R) model. The local cluster abundance, when combined with geometric and high redshift data from the cosmic microwave background, supernovae, H_0 and baryon acoustic oscillations, im...
Solar system constraints on Rn gravity
Recently, gravitational microlensing has been investigated in the framework of the weak field limit of fourth order gravity theory. However, solar system data (i.e. planetary periods and light bending) can be used to put strong constraints on the parameters of this class of gravity theories. We find that these parameters must be very close to those corresponding to the Newtonian limit of the theory
Constraint Solving for Diagnosing Concurrency Bugs
Khoshnood, Sepideh
2015-01-01
Programmers often have to spend a significant amount of time inspecting the software code and execution traces to identify the root cause of a software bug. For a multithreaded program, debugging is even more challenging due to the subtle interactions between concurrent threads and the often astronomical number of possible interleavings. In this work, we propose a logical constraint-based symbolic analysis method to aid in the diagnosis of concurrency bugs and find their root causes, which ca...
Embedded System Synthesis under Memory Constraints
Madsen, Jan; Bjørn-Jørgensen, Peter
This paper presents a genetic algorithm to solve the system synthesis problem of mapping a time constrained single-rate system specification onto a given heterogeneous architecture which may contain irregular interconnection structures. The synthesis is performed under memory constraints, that is......, the algorithm takes into account the memory size of processors and the size of interface buffers of communication links, and in particular the complicated interplay of these. The presented algorithm is implemented as part of the LY-COS cosynthesis system....
Big Bang Nucleosynthesis constraints on new physics
Primordial Nucleosynthesis provides a probe of the physics of the early Universe when the temperature and particle densities are high. The Cosmic Nuclear Reactor may, thereby, lead to constraints on new physics which may be inaccessible to current accelerators. Current Big Bang Nucleosynthesis (BBN) bounds to the existence and/or properties of new particles are reviewed and used to constrain physics 'beyond the standard model.' (orig.)
Redshift drift constraints on holographic dark energy
He, Dong-Ze; Zhang, Jing-Fei; Xin ZHANG
2016-01-01
The Sandage-Loeb (SL) test is a promising method for probing dark energy because it measures the redshift drift in the spectra of Lyman-$\\alpha$ forest of distant quasars, covering the "redshift desert" of $2\\lesssim z\\lesssim5$, which is not covered by existing cosmological observations. Therefore, it could provide an important supplement to current cosmological observations. In this paper, we explore the impact of SL test on the precision of cosmological constraints for two typical holograp...
Constraints on Large-Block Shareholders
Clifford Holderness; Dennis P. Sheehan
1998-01-01
Corporate managers who own a majority of the common stock in their company or who represent another firm owning such an interest appear to be less constrained than managers of diffusely held firms, yet their power to harm minority shareholders must be circumscribed by some organizational or legal arrangements. Empirical investigations reveal that boards of directors in majority-owned firms are little different from firms with diffuse stock ownership. Another source of constraints on a majorit...
Cosmological Constraints on a Power Law Universe
Sethi, G; Jain, D; Sethi, Geetanjali; Dev, Abha; Jain, Deepak
2005-01-01
Linearly coasting cosmology is comfortably concordant with a host of cosmological observations. It is surprisingly an excellent fit to SNe Ia observations and constraints arising from age of old quasars. In this article we highlight the overall viability of an open linear coasting cosmological model.The model is consistent with the latest SNe Ia ``gold'' sample and accommodates a very old high-redshift quasar, which the standard cold-dark model fails to do.
Cosmological constraints on a power law universe
Linearly coasting cosmology is comfortably concordant with a host of cosmological observations. It is surprisingly an excellent fit to SNe Ia observations and constraints arising from age of old quasars. In this Letter we highlight the overall viability of an open linear coasting cosmological model. The model is consistent with the latest SNe Ia 'gold' sample and accommodates a very old high-redshift quasar, which the standard cold-dark model fails to do
Variational calculus with constraints on general algebroids
Grabowska, Katarzyna; Grabowski, Janusz
2007-01-01
Variational calculus on a vector bundle E equipped with a structure of a general algebroid is developed, together with the corresponding analogs of Euler-Lagrange equations. Constrained systems are introduced in the variational and in the geometrical setting. The constrained Euler-Lagrange equations are derived for analogs of holonomic, vakonomic and nonholonomic constraints. This general model covers majority of first-order Lagrangian systems which are present in the literature and reduces t...
Restructuring of Public Enterprises udner Political Constraint
Dong Keun Cho
1996-01-01
A typical public enterprise suffering from low productivity and overemployment may be reformed by removing protective measures and/or offering new incentive schemes. This paper addresses issues of resturcturing through incentive wage scheme. The key factor in the process of restructuring is the possible resistance of existing workers to reform plan. Hence, political constraint which requires utility level under reform to be at least equal to pre-reform level incurs substantial financial costs...
Nonlinear constraints on gravity from entanglement
Banerjee, Shamik; Kaviraj, Apratim; Sinha, Aninda
2014-01-01
Using the positivity of relative entropy arising from the Ryu-Takayanagi formula for spherical entangling surfaces, we obtain constraints at the nonlinear level for the gravitational dual. We calculate the Green's function necessary to compute the first order correction to the entangling surface and use this to find the relative entropy for non-constant stress tensors in a derivative expansion. We show that the Einstein value satisfies the positivity condition while the multi-dimensional para...
Fingerprinting differential active site constraints of ATPases
Hacker, Stephan M.; Hardt, Norman; Buntru, Alexander; Pagliarini, Dana; Möckel, Martin; Mayer, Thomas U; Scheffner, Martin; Hauck, Christof R.; Marx, Andreas
2013-01-01
The free energy provided by adenosine triphosphate (ATP) hydrolysis is central to many cellular processes and, therefore, the number of enzymes utilizing ATP as a substrate is almost innumerable. Modified analogues of ATP are a valuable means to understand the biological function of ATPases. Although these enzymes have evolved towards binding to ATP, large differences in active site architectures were found. In order to systematically access the specific active site constraints of different A...
Constraints on three flavor neutrino mixing
Mohan Narayan
2000-01-01
We summarize the constraints on three ﬂavor neutrino mixing coming from data. We ﬁrst map out the allowed region in the three neutrino parameter space using solar and atmospheric neutrino data. We then incorporate the results of reactor and long baseline experiments in our analysis and show that the parameter space is drastically reduced. We conclude by pointing out that the results of Borexino and SNO will further help in constraining the parameter space.
Credit Constraints And Training After Job Loss
Bruce Chapman; Thomas F. Crossley; Taejong Kim
2003-01-01
It is a widely held view that imperfect capital markets mean that individuals from poor backgrounds cannot borrow in order to finance educational investments. This view pervades policy formation, and is reflected in the fact that post-compulsory education processes in all countries involve considerable government intervention and large public subsidies. But are the existence of credit constraints an empirical reality? This paper uses unique data to take a new approach to this question. Specif...
Child Labor, Crop Shocks, and Credit Constraints
Kathleen Beegle; Rajeev Dehejia; Roberta Gatti
2003-01-01
This paper examines the relationship between household income shocks and child labor. In particular, we investigate the extent to which transitory income shocks lead to increases in child labor and whether household access to credit mitigates the effects of these shocks. Using panel data from a survey in Tanzania, we find that both relationships are significant. Our results suggest that credit constraints play a role in explaining child labor and consequently that child labor is inefficient, ...
Dynamical aspects of behavior generation under constraints
Kozma, Robert; Harter, Derek; Achunala, Srinivas
2007-01-01
Dynamic adaptation is a key feature of brains helping to maintain the quality of their performance in the face of increasingly difficult constraints. How to achieve high-quality performance under demanding real-time conditions is an important question in the study of cognitive behaviors. Animals and humans are embedded in and constrained by their environments. Our goal is to improve the understanding of the dynamics of the interacting brain–environment system by studying human behaviors when ...
Main constraints in developing public organic procurement
Spigarolo, Roberto; Sarti, Valerio; Bocchi, Stefano; Giorgi, Giulio
2010-01-01
The present study investigates how to increase and improve school catering supply chains, to understand hindering factors and their perception in order to reveal drivers and constraints for POP. These include policy implementation instruments, changed values and attitudes, healthy nutrition policies, supply chain bottle necks, premium prices (to producers), successful procurement strategies and certification procedures. This work is based on a two-step survey concerning the Italian school ...
Economic Growth in Croatia: Potential and Constraints
David Moore; Athanasios Vamvakidis
2008-01-01
This paper examines the factors and constraints that affect recent and potential growth in Croatia, as well as policies that can influence it. On current productivity trends, it estimates Croatia’s potential growth rate at 4–4½ percent, a result reasonably robust to different methodologies. For growth to be sustained at a significantly higher rate, the business environment needs to be improved through further measures to reduce the administrative burden, legal uncertainties, and corruption. T...
Stability constraints in triplet extension of MSSM
Das, Moumita; Roy, Sourov
2015-01-01
We study the stability constraints on the parameter space of a triplet extension of MSSM. Existence of unbounded from below directions in the potential can spoil successful Electroweak (EW) symmetry breaking by making the corresponding minimum unstable, and hence the model should be free from those directions. Avoiding those directions restricts the parameter space of the model. We derive four stability constraints, of which only three independent from each other. After scanning the model's parameter space for phenomenologically viable data points, we impose the stability constraints and find that only about a quarter of the data points features a stable EW minimum. At those data points featuring stability, $\\mu$ and the up Higgs soft mass turn out to be smaller than about a TeV in absolute value, which make the mass of the lightest chargino and neutralino smaller than about 700 GeV. Two relevant phenomenological consequences of lifting the unbounded from below directions are that the lightest Higgs boson dec...
Use of dose constraints in medical exposure
Medical-related radiation is the largest source of controllable radiation exposure to humans and it accounts for more than 95% of radiation exposure from man-made sources. Medical exposure to radiation is exposure incurred by patients as part of their own medical or dental diagnosis or treatment; by persons, other than those occupationally exposed, knowingly, while voluntarily helping in the support and comfort of patients; and by volunteers in a programme of biomedical research involving their exposure. Because it is planned exposure, medical exposure has to conform to a set of principles of protection that apply equally to all controllable exposure situations: the principle of justification, the principle of optimisation of protection, and the principle of application of limits on maximum doses in planned situations. In this study the concept of dose constraints is being scrutinized to see if it can be applied in medical exposures and the benefits of such restrictions. Dose constraints can only be applied to exposure to persons voluntary helping in the support and comfort of patients as well as volunteers in the programme of biomedical research. There are no dose constraints for patients but the concept of reference levels applies. (au)
Tail Risk Constraints and Maximum Entropy
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.
Dynamical dark energy: Current constraints and forecasts
Upadhye, A; Steinhardt, P J; Upadhye, Amol; Ishak, Mustapha; Steinhardt, Paul J.
2004-01-01
We consider how well the dark energy equation of state $w$ as a function of red shift $z$ will be measured using current and anticipated experiments. We use a procedure which takes fair account of the uncertainties in the functional dependence of $w$ on $z$, as well as the parameter degeneracies, and avoids the use of strong prior constraints. We apply the procedure to current data from WMAP, SDSS, and the supernova searches, and obtain results that are consistent with other analyses using different combinations of data sets. The effects of systematic experimental errors and variations in the analysis technique are discussed. Next, we use the same procedure to forecast the dark energy constraints achieveable by the end of the decade, assuming 8 years of WMAP data and realistic projections for ground-based measurements of supernovae and weak lensing. We find the $2 \\sigma$ constraints on the current value of $w$ to be $\\Delta w_0 (2 \\sigma) = 0.12$, and on $dw/dz$ (between $z=0$ and $z=1$) to be $\\Delta w_1 (2...
Constraints on muon-specific dark forces
Karshenboim, Savely G; Pospelov, Maxim
2014-01-01
The recent measurement of the Lamb shift in muonic hydrogen allows for the most precise extraction of the charge radius of the proton which is currently in conflict with other determinations based on $e-p$ scattering and hydrogen spectroscopy. This discrepancy could be the result of some new muon-specific force with O(1-100) MeV force carrier---in this paper we concentrate on vector mediators. Such an explanation faces challenges from the constraints imposed by the $g-2$ of the muon and electron as well as precision spectroscopy of muonic atoms. In this work we complement the family of constraints by calculating the contribution of hypothetical forces to the muonium hyperfine structure. We also compute the two-loop contribution to the electron parity violating amplitude due to a muon loop, which is sensitive to the muon axial-vector coupling. Overall, we find that the combination of low-energy constraints favors the mass of the mediator to be below 10 MeV, and that a certain degree of tuning is required betwe...
Models of $\\mu$ Her with asteroseismic constraints
Yang, W
2009-01-01
Using the Yale stellar evolution code, models of mu Her based on asteroseismic measurements are constructed. A $\\chi^{2}$ minimization is performed to approach the best modeling parameters which reproduce the observations within their errors. By combining all non-asteroseismic constraints with asteroseismic measurements, we find that the observational constraints favour a model with a mass of 1.00$^{+ 0.01}_{- 0.02}$ $M_{\\odot}$, an age t = 6.433 $\\pm$ 0.04 Gyr, a mixing-length parameter $\\alpha$ = 1.75 $\\pm$ 0.25, an initial hydrogen abundance $X_{i}$ = 0.605$^{+ 0.01}_{- 0.005}$ and metal abundance $Z_{i}$ = 0.0275$^{+ 0.002}_{- 0.001}$. mu Her is in post-main sequence phase of evolution. The modes of $l$ = 1 show up the characteristics of avoided crossings, which may be applied to test the internal structure of this type stars. Asteroseismic measurements can be used as a complementary constraint on the modeling parameters. The models with mass 1.00 - 1.10 $M_{\\odot}$ can reproduce the observational constra...
Constraints on stellar evolution from pulsations
Consideration of the many types of intrinsic variable stars, that is, those that pulsate, reveals that perhaps a dozen classes can indicate some constraints that affect the results of stellar evolution calculations, or some interpretations of observations. Many of these constraints are not very strong or may not even be well defined yet. In this review we discuss only the case for six classes: classical Cepheids with their measured Wesselink radii, the observed surface effective temperatures of the known eleven double-mode Cepheids, the pulsation periods and measured surface effective temperatures of three R CrB variables, the delta Scuti variable VZ Cnc with a very large ratio of its two observed periods, the nonradial oscillations of our sun, and the period ratios of the newly discovered double-mode RR Lyrae variables. Unfortunately, the present state of knowledge about the exact compositions; mass loss and its dependence on the mass, radius, luminosity, and composition; ;and internal mixing processes, as well as sometimes the more basic parameters such as luminosities and surface effective temperatures prevent us from applying strong constraints for every case where currently the possibility exists
Nonabelian dark matter: models and constraints
Chen, Fang; Frey, Andrew R
2009-01-01
Numerous experimental anomalies hint at the existence of a dark matter (DM) multiplet chi_i with small mass splittings. We survey the simplest such models which arise from DM in the low representations of a new SU(2) gauge symmetry, whose gauge bosons have a small mass mu 4e annihilation channel, for explaining PAMELA, Fermi, and INTEGRAL/SPI lepton excesses, while remaining consistent with constraints from relic density, diffuse gamma rays and the CMB. This consistency is strengthened if DM annihilations occur mainly in subhalos, while excitations (relevant to the excited DM proposal to explain the 511 keV excess) occur in the galactic center (GC), due to higher velocity dispersions in the GC, induced by baryons. We derive new constraints and predictions which are generic to these models. Notably, decays of excited DM states chi' -> chi gamma arise at one loop and could provide a new signal for INTEGRAL/SPI; big bang nucleosynthesis (BBN) constraints on the density of dark SU(2) gauge bosons imply a lower b...
HUBBLE PARAMETER MEASUREMENT CONSTRAINTS ON DARK ENERGY
We use 21 Hubble parameter versus redshift data points from Simon et al., Gaztañaga et al., Stern et al., and Moresco et al. to place constraints on model parameters of constant and time-evolving dark energy cosmologies. The inclusion of the eight new measurements results in H(z) constraints more restrictive than those derived by Chen and Ratra. These constraints are now almost as restrictive as those that follow from current Type Ia supernova (SNIa) apparent magnitude versus redshift data, which now more carefully account for systematic uncertainties. This is a remarkable result. We emphasize, however, that SNIa data have been studied for a longer time than the H(z) data, possibly resulting in a better estimate of potential systematic errors in the SNIa case. A joint analysis of the H(z), baryon acoustic oscillation peak length scale, and SNIa data favors a spatially flat cosmological model currently dominated by a time-independent cosmological constant but does not exclude slowly evolving dark energy.
Cosmological constraints on the Undulant Universe
Tian Lan; Yan Gong; Hao-Yi Wan; Tong-Jie Zhang
2010-01-01
We use the redshifi Hubble parameter H(z)data derived from relative galaxy ages,distant type Ⅰa supernovae(SNe Ⅰa),the Baryonic Acoustic Oscillation (BAO)peak,and the Cosmic Microwave Background(CMB)shift parameter data,to constrain cosmological parameters in the Undulant Universe.We marginalize the likelihood functions over h by integrating the probability density P ∝ e-x2/2.By using a Markov Chain Monte Carlo(MCMC)technique,we obtain the best fitting results and give the confidence regions in the b-Ωm0 plane.Then we compare their constraints.Our results show that the H(z)data play a similar role with the SNe Ia data in cosmological study.By presenting the independent and joint constraints,we find that the BAO and CMB data play very important roles in breaking the degeneracy compared with the H(z)and SNe Ⅰa data alone.Combined with the BAO or CMB data,one can remarkably improve the constraints.The SNe Ia data sets constrain Ωm0 much tighter than the H(z)data sets,but the H(z)data sets constrain b much tighter than the SNe Ⅰa data sets.All these results show that the Undulant Universe approaches the ACDM model.We expect more H(z)data to constrain cosmological parameters in the future.
Cosmological constraints on the Undulant Universe
We use the redshift Hubble parameter H(z) data derived from relative galaxy ages, distant type Ia supernovae (SNe Ia), the Baryonic Acoustic Oscillation (BAO) peak, and the Cosmic Microwave Background (CMB) shift parameter data, to constrain cosmological parameters in the Undulant Universe. We marginalize the likelihood functions over h by integrating the probability density P ∝ e-χ2/2 By using a Markov Chain Monte Carlo (MCMC) technique, we obtain the best fitting results and give the confidence regions in the b - Ωm0 plane. Then we compare their constraints. Our results show that the H(z) data play a similar role with the SNe Ia data in cosmological study. By presenting the independent and joint constraints, we find that the BAO and CMB data play very important roles in breaking the degeneracy compared with the H(z) and SNe Ia data alone. Combined with the BAO or CMB data, one can remarkably improve the constraints. The SNe Ia data sets constrain Ωm0 much tighter than the H(z) data sets, but the H(z) data sets constrain b much tighter than the SNe Ia data sets. All these results show that the Undulant Universe approaches the ΛCDM model. We expect more H(z) data to constrain cosmological parameters in the future. (research papers)
Preservation of Linear Constraints in Approximation of Tensors
Eugene Tyrtyshnikov
2009-01-01
For an arbitrary tensor (multi-index array) with linear constraints at each direction, it is proved that the factors of any minimal canonical tensor approximation to this tensor satisfy the same linear constraints for the corresponding directions.
Differential constraints and exact solutions of nonlinear diffusion equations
The differential constraints are applied to obtain explicit solutions of nonlinear diffusion equations. Certain linear determining equations with parameters are used to find such differential constraints. They generalize the determining equations used in the search for classical Lie symmetries
Differential constraints and exact solutions of nonlinear diffusion equations
Kaptsov, Oleg V.; Verevkin, Igor V.
2002-01-01
The differential constraints are applied to obtain explicit solutions of nonlinear diffusion equations. Certain linear determining equations with parameters are used to find such differential constraints. They generalize the determining equations used in the search for classical Lie symmetries.
Specifying Usage Control ModelWith Object Constraint Language
Min Li
2013-02-01
Full Text Available The recent usage control model (UCON is a foundation for next-generation access control models with distinguishing properties of decision continuity and attribute mutability. Constraints in UCON are one of the most important components that have involved in the principle motivations of usage analysis and design. The importance of constraints associated with authorizations, obligations, and conditions in UCON has been recognized but modeling these constraints has not been received much attention. In this paper we use a de facto constraints specification language in software engineering to analyze the constraints in UCON model. We show how to represent constraints with object constraint language (OCL and give out a formalized specification of UCON model which is built from basic constraints, such as authorization predicates, obligation actions and condition requirements. Further, we show the flexibility and expressive capability of this specified UCON model with extensive examples.
Constraints management and value chain performance for sustainable development
Richard Bitange Nyaoga; Peterson Obara Magutu
2016-01-01
Managers are ever seeking for better ways of managing their constraints to improve their company’s value chain performance and competitiveness. Although previous literature explored constraint management, it was inconclusive as to how constraint management could affect the value chain performance in tea processing chains. The purpose of this study is to determine the relationship between constraint management and firm value chain performance of tea processing firms. This study undertook an em...
Consistent Algorithm for Multi-value Constraint with Continuous Variables
无
1999-01-01
Mature algorithms for the Constraint Satisfaction Problem (CSP) of binary constraint with discrete variables have already been obtained for the application. For the instance of multi-value constraint with continuous variables, the approach will be quite different and the difficulty of settling will aggrandize a lot. This paper presents the algorithm for realizing global consistency of continuous variable. And this algorithm can be applied to multi-value constraint.
The CP 1998 Workshop on Constraint Problem Reformulation
Frank, Jeremy
1999-01-01
On 30 October 1998, Mihaela Sabin and I ran the Constraint Problem Reformulation Workshop in conjunction with the Fourth International Conference on the Principles and Practices of Constraint Programming held in Pisa, Italy. The goals of the workshop were to discuss the nature of constraint problem reformulation and the benefits and difficulties in reformulating constraint problems and to summarize and understand the recent work in this area.
Combining Constraint Types From Public Data in Aerial Image Segmentation
Jacobsen, Thomas Stig; Jensen, Jacob Jon; Jensen, Daniel Rune;
2013-01-01
We introduce a method for image segmentation that constraints the clustering with map and point data. The method is showcased by applying the spectral clustering algorithm on aerial images for building detection with constraints built from a height map and address point data. We automatically det...... building clusters. Our evaluation show that the combination of constraints have a positive impact on the clustering quality achieved. Finally we argue how the presented constraint types may be used in other applications....
SAT Encoding and CSP Reduction for Interconnected Alldiff Constraints
Lardeux, Frederic; Monfroy, Eric; Saubion, Frederic; Crawford, Broderick; Castro, Carlos
Constraint satisfaction problems (CSP) or Boolean satisfiability problem (SAT) are two well known paradigm to model and solve combinatorial problems. Modeling and resolution of CSP is often strengthened by global constraints (e.g., Alldiff constraint). This paper highlights two different ways of handling specific structural information: a uniform propagation framework to handle (interleaved) Alldiff constraints with some CSP reduction rules; and a SAT encoding of these rules that preserves the reduction properties of CSP.
The Efficiency of Constraint Based Routing in MPLS Networks
Martin Medvecky
2011-01-01
Full Text Available The paper presents the simulation results and evaluates the efficiency of constraint base routing algorithms used in MPLS network from the point of their usability in Next Generation Networks. The efficiency of constraint based routing is evaluated according following criteria: optimal path selection, routing priority of traffic flows selected for constraint routing and bandwidth allocation by MAM or RDM bandwidth constraints models.
Decomposition During Search for Propagation-Based Constraint Solvers
Mann, Martin; Tack, Guido; Will, Sebastian
2007-01-01
We describe decomposition during search (DDS), an integration of And/Or tree search into propagation-based constraint solvers. The presented search algorithm dynamically decomposes sub-problems of a constraint satisfaction problem into independent partial problems, avoiding redundant work. The paper discusses how DDS interacts with key features that make propagation-based solvers successful: constraint propagation, especially for global constraints, and dynamic search heuristics. We have impl...
On Implicit Active Constraints in Linear Semi-Infinite Programs with Unbounded Coefficients
Goberna, M. A., E-mail: mgoberna@ua.es [Alicante University, Dep. of Statistics and Operations Research (Spain); Lancho, G. A., E-mail: lanchoga@mixteco.utm.mx [Universidad Tecnologica de Mixteca, Instituto de Fisica y Matematicas (Mexico); Todorov, M. I., E-mail: maxim.todorov@udlap.mx [UDLA, Dep. of Physics and Mathematics (Mexico); Vera de Serio, V. N., E-mail: vvera@uncu.edu.ar [Universidad Nacional de Cuyo, Facultad de Ciencias Economicas, Instituto de Ciencias Basicas (Argentina)
2011-04-15
The concept of implicit active constraints at a given point provides useful local information about the solution set of linear semi-infinite systems and about the optimal set in linear semi-infinite programming provided the set of gradient vectors of the constraints is bounded, commonly under the additional assumption that there exists some strong Slater point. This paper shows that the mentioned global boundedness condition can be replaced by a weaker local condition (LUB) based on locally active constraints (active in a ball of small radius whose center is some nominal point), providing geometric information about the solution set and Karush-Kuhn-Tucker type conditions for the optimal solution to be strongly unique. The maintaining of the latter property under sufficiently small perturbations of all the data is also analyzed, giving a characterization of its stability with respect to these perturbations in terms of the strong Slater condition, the so-called Extended-Nuernberger condition, and the LUB condition.
Free-space optical communications with peak and average constraints: High SNR capacity approximation
Chaaban, Anas
2015-09-07
The capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel with both average and peak intensity constraints is studied. A new capacity lower bound is derived by using a truncated-Gaussian input distribution. Numerical evaluation shows that this capacity lower bound is nearly tight at high signal-to-noise ratio (SNR), while it is shown analytically that the gap to capacity upper bounds is a small constant at high SNR. In particular, the gap to the high-SNR asymptotic capacity of the channel under either a peak or an average constraint is small. This leads to a simple approximation of the high SNR capacity. Additionally, a new capacity upper bound is derived using sphere-packing arguments. This bound is tight at high SNR for a channel with a dominant peak constraint.
Stinchcomb, W. W.; Reifsnider, K. L.; Yeung, P.; Gibbins, M. N.
1979-01-01
An investigative program is presented in an attempt to add to the current understanding of constraint effects on the response of composite materials under cyclic loading. The objectives were: (1) to use existing data and to develop additional data in order to establish an understanding and quantitative description of flaw growth in unidirectional lamina under cyclic loading at different load direction to fiber direction angles; (2) to establish a similar understanding and description of flaw growth in lamina which are embedded in laminates between other unflawed lamina; (3) to determine the nature of the influence of constraint on flaw growth by quantitatively comparing the results of the tests; and (4) to develop a model and philosophy of constraints effects based on our investigative results.
Using Multiple Sources of Information for Constraint-Based Morphological Disambiguation
Tur, G
1999-01-01
This thesis presents a constraint-based morphological disambiguation approach that is applicable to languages with complex morphology--specifically agglutinative languages with productive inflectional and derivational morphological phenomena. For morphologically complex languages like Turkish, automatic morphological disambiguation involves selecting for each token morphological parse(s), with the right set of inflectional and derivational markers. Our system combines corpus independent hand-crafted constraint rules, constraint rules that are learned via unsupervised learning from a training corpus, and additional statistical information obtained from the corpus to be morphologically disambiguated. The hand-crafted rules are linguistically motivated and tuned to improve precision without sacrificing recall. In certain respects, our approach has been motivated by Brill's recent work, but with the observation that his transformational approach is not directly applicable to languages like Turkish. Our approach a...
Adaptive neural control for an uncertain robotic manipulator with joint space constraints
Tang, Zhong-Liang; Ge, Shuzhi Sam; Tee, Keng Peng; He, Wei
2016-07-01
In this paper, adaptive neural tracking control is proposed for a robotic manipulator with uncertainties in both manipulator dynamics and joint actuator dynamics. The manipulator joints are subject to inequality constraints, i.e., the joint angles are required to remain in some compact sets. Integral barrier Lyapunov functionals (iBLFs) are employed to address the joint space constraints directly without performing an additional mapping to the error space. Neural networks (NNs) are utilised to compensate for the unknown robot dynamics and external force. Adapting parameters are developed to estimate the unknown bounds on NN approximations. By the Lyapunov synthesis, the proposed control can guarantee the semi-global uniform ultimate boundedness of the closed-loop system, and the practical tracking of joint reference trajectory is achieved without the violation of predefined joint space constraints. Simulation results are given to validate the effectiveness of the proposed control scheme.
The effect of parking orbit constraints on the optimization of ballistic planetary trajectories
Sauer, C. G., Jr.
1984-01-01
The optimization of ballistic planetary trajectories is developed which includes constraints on departure parking orbit inclination and node. This problem is formulated to result in a minimum total Delta V where the entire constrained injection Delta V is included in the optimization. An additional Delta V is also defined to allow for possible optimization of parking orbit inclination when the launch vehicle orbit capability varies as a function of parking orbit inclination. The optimization problem is formulated using primer vector theory to derive partial derivatives of total Delta V with respect to possible free parameters. Minimization of total Delta V is accomplished using a quasi-Newton gradient search routine. The analysis is applied to an Eros rendezvous mission whose transfer trajectories are characterized by high values of launch asymptote declination during particular launch opportunities. Comparisons in performance are made between trajectories where parking orbit constraints are included in the optimization and trajectories where the constraints are not included.
THE TANGENT CONES ON CONSTRAINT QUALIFICATIONS IN OPTIMIZATION PROBLEMS
Huang Longguang
2008-01-01
This article proposes a few tangent cones, which are relative to the constraint qualifications of optimization problems. With the upper and lower directional derivatives of an objective function, the characteristics of cones on the constraint qualifications are presented. The interrelations among the constraint qualifications, a few cones involved,and level sets of upper and lower directional derivatives are derived.
Strategic Planning under Severe Constraints in a State College
Geisler, Jerry L.; Gilliard, Debbie J.
2007-01-01
This paper examines the difficulties of strategic planning under severe constraints in a state college. Constraints include the planning models available, the governance structure of the college and other externalities, and a not-for-profit model of constraints by Newman and Wallender. After presenting the planning challenges, we discuss…
A generalised finite domain constraint solver for SWI-Prolog
M. Triska; U. Neumerkel; J. Wielemaker
2008-01-01
In this paper we describe a new constraint solver over finite domains that has recently been included in the SWI-Prolog distribution 1. Our solver generalises finite domain constraint solving towards unbounded domains, and thus enables a uniform approach to integer arithmetic and constraints. We ens
Graph Invariants as Necessary Conditions for Global Constraints
Beldiceanu, Nicolas; Carlsson, Mats; Rampon, Jean-Xavier; Truchet, Charlotte
2005-01-01
This report presents a database of about 200 graph invariants for deriving systematically necessary conditions from the graph properties based representation of global constraints. This scheme is based on invariants on the graph characteristics used in the description of a global constraint. A SICStus Prolog implementation based on arithmetic and logical constraints as well as on indexicals is available.
Extended Set Constraints and Tree Grammar Abstraction of Programs
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 ill...
Dorina Ardelean; Daniela Popa
2012-01-01
Use of food additives in food is determined by the growth of contemporary food needs of the world population. Additives used in food, both natural and artificial ones, contribute to: improving the organoleptic characteristics and to preserve the food longer, but we must not forget that all these additives should not be found naturally in food products. Some of these additives are not harmful and human pests in small quantities, but others may have harmful effects on health.
Natural food additives: Quo vadis?
Carocho, Márcio; Morales, Patricia; Isabel C. F. R. Ferreira
2015-01-01
In a time where the public is more aware and interested with what they eat, natural additives have been gaining interest both from the food industries and the consumers. Some studies show that consumers prefer food prepared with natural additives rather than chemical ones, due to health reasons. Although quite promising, natural additives still face some drawbacks and limitations as well as conflicting information. In this manuscript, the most important natural additives are overviewed, as we...
Dorina Ardelean
2012-01-01
Full Text Available Use of food additives in food is determined by the growth of contemporary food needs of the world population. Additives used in food, both natural and artificial ones, contribute to: improving the organoleptic characteristics and to preserve the food longer, but we must not forget that all these additives should not be found naturally in food products. Some of these additives are not harmful and human pests in small quantities, but others may have harmful effects on health.
Two-period resource duopoly with endogenous intertemporal capacity constraints
Berk, Istemi
2014-07-15
This paper analyzes the strategic firm behavior within the context of a two-period resource duopoly model in which firms face endogenous intertemporal capacity constraints. Firms are allowed to invest in capacity in between two periods in order to increase their initial endowment of exhaustible resource stocks. Using this setup, we nd that the equilibrium price weakly decreases over time. Moreover, asymmetric distribution of initial resource stocks leads to a significant change in equilibrium outcome, provided that firms do not have the same cost structure in capacity additions. It is also verified that if only one company is capable of investment in capacity, the market moves to a more concentrated structure in the second period.
QCD constraints on the equation of state for compact stars
Fraga, E. S.; Kurkela, A.; Schaffner-Bielich, J.; Vuorinen, A.
2016-01-01
In recent years, there have been several successful attempts to constrain the equation of state of neutron star matter using input from low-energy nuclear physics and observational data. We demonstrate that significant further restrictions can be placed by additionally requiring the pressure to approach that of deconfined quark matter at high densities. Remarkably, the new constraints turn out to be highly insensitive to the amount - or even presence - of quark matter inside the stars. In this framework, we also present a simple effective equation of state for cold quark matter that consistently incorporates the effects of interactions and furthermore includes a built-in estimate of the inherent systematic uncertainties. This goes beyond the MIT bag model description in a crucial way, yet leads to an equation of state that is equally straightforward to use.
Effective multicasting algorithm for dynamic membership with delay constraint
CHEN Lin; XU Zheng-quan
2006-01-01
This paper proposes an effective heuristic algorithm for dynamic multicast routing with delay-constrained DDMR.The tree constructed by DDMR has the following characteristics: (1) multicast tree changes with the dynamic memberships; (2)the cost of the tree is as small as possible at each node addition/removal event; (3) all of the path delay meet a fixed delay constraint;(4) minimal perturbation to an existing tree. The proposed algorithm is based on "damage" and "usefulness" concepts proposed in previous work, and has a new parameter bf(Balancing Factor) for judging whether or not to rearrange a tree region when membership changes. Mutation operation in Genetic Algorithm (GA) is also employed to find an attached node for a new adding node.Simulation showed that our algorithm performs well and is better than static heuristic algorithms, in term of cost especially.
Constraints on Galactic Wino Densities from Gamma Ray Lines
Baumgart, Matthew; Vaidya, Varun
2014-01-01
We systematically compute the annihilation rate for neutral winos into the final state gamma + X, including all leading radiative corrections. This includes both the Sommerfeld enhancement (in the decoupling limit for the Higgsino) and the resummation of the leading electroweak double logarithms. Adopting an analysis of the HESS experiment, we place constraints on the mass as a function of the wino fraction of the dark matter and the shape of the dark matter profile. We also determine how much coring is needed in the dark matter halo to make the wino a viable candidate as a function of its mass. Additionally, as part of our effective field theory formalism, we show that in the pure-Standard Model sector of our theory, emissions of soft Higgses are power-suppressed and that collinear Higgs emission does not contribute to leading double logs.
Constraints on galactic wino densities from gamma ray lines
Baumgart, Matthew; Rothstein, Ira Z.; Vaidya, Varun
2015-04-01
We systematically compute the annihilation rate for neutral winos into the final state γ + X, including all leading radiative corrections. This includes both the Sommerfeld enhancement (in the decoupling limit for the Higgsino) and the resummation of the leading electroweak double logarithms. Adopting an analysis of the HESS experiment, we place constraints on the mass as a function of the wino fraction of the dark matter and the shape of the dark matter profile. We also determine how much coring is needed in the dark matter halo to make the wino a viable candidate as a function of its mass. Additionally, as part of our effective field theory formalism, we show that in the pure-Standard Model sector of our theory, emissions of soft Higgses are power-suppressed and that collinear Higgs emission does not contribute to leading double logs.
Driver beam-led EURISOL target design constraints
Noah, Etam; Catherall, Richard; Kadi, Yacine; Kharoua, Cyril; Lettry, Jacques
2008-01-01
The EURISOL (European Isotope Separation Online) Design Study is addressing new high power target design challenges. A three-step method [1] was proposed to split the high power linac proton driver beam into one $H^{-}$ branch for the 4 $MW_{b}$ [2] mercury target that produces radioactive ion beams (RIB) via spallation neutroninduced fission in a secondary actinide target and three 100 $kW_{b}$ $H^{+}$ branches for the direct targets producing RIBs via fragmentation and spallation reactions. This scheme minimises transient thermo-mechanical stresses on targets and preserves the cw nature of the driver beam in the four branches. The heat load for oxides, carbides, refractory metal foils and liquid metals is driven by the incident proton driver beam while for actinides, exothermic fission reactions are an additional contribution. This paper discusses the constraints that are specific to each class of material and the target design strategies.
Methods to improve constraint-induced movement therapy.
Tarkka, Ina M; Könönen, Mervi
2009-01-01
In global terms, cerebrovascular stroke is the leading cause of long-term disability. Despite improved acute phase management of stroke, the majority of survivors are disabled and many require effective rehabilitation. Constraint-induced movement therapy (CIMT) is one of the recently emerging therapies for subjects with stroke. The effects of two-week long CIMT on behavioural, neurophysiologic and neuroimaging measures in subjects with chronic stroke were studied. Furthermore, the effects of combined upper limb exercise and peripheral preprogrammed multichannel electrical stimulation, i.e. functional electrical therapy (FET), were evaluated. Behavioral gains were obtained in hand function and functional MRI activations, and, in addition, TMS responses appeared more laterally and/or bilaterally in the affected hemisphere in the subjects after CIMT. Neurophysiologic and functional imaging results were supportive evidence for the benefits of use-dependent plasticity in subjects with chronic stroke. PMID:19713619
Constraints on the symmetry noninheriting scalar black hole hair
Smolić, Ivica
2016-01-01
Any recipe to grow black hole hair has to circumvent no-hair theorems by violating some of their assumptions. Recently discovered hairy black hole solutions exist due to the fact that their scalar fields don't inherit the symmetries of the spacetime metric. We present here a general analysis of the constraints which limit the possible forms of such a hair, for both the real and the complex scalar fields. These results can be taken as a novel piece of the black hole uniqueness theorems or simply as a symmetry noninheriting ans\\"atze guide. In addition we introduce new classification of the gravitational field equations which might prove useful for various generalizations of the theorems about spacetimes with symmetries.
Minimum weight design of rectangular and tapered helicopter rotor blades with frequency constraints
Chattopadhyay, Aditi; Walsh, Joanne L.
1988-01-01
The minimum weight design of a helicopter rotor blade subject to constraints on coupled flap-lag natural frequencies has been studied. A constraint has also been imposed on the minimum value of the autorotational inertia of the blade in order to ensure that it has sufficient inertia to autorotate in the case of engine failure. The program CAMRAD is used for the blade modal analysis and CONMIN is used for the optimization. In addition, a linear approximation analysis involving Taylor series expansion has been used to reduce the analysis effort. The procedure contains a sensitivity analysis which consists of analytical derivatives of the objective function and the autorotational inertia constraint and central finite difference derivatives of the frequency constraints. Optimum designs have been obtained for both rectangular and tapered blades. Design variables include taper ratio, segment weights, and box beam dimensions. It is shown that even when starting with an acceptable baseline design, a significant amount of weight reduction is possible while satisfying all the constraints for both rectangular and tapered blades.
Animal movement constraints improve resource selection inference in the presence of telemetry error
Brost, Brian M.; Hooten, Mevin B.; Hanks, Ephraim M.; Small, Robert J.
2016-01-01
Multiple factors complicate the analysis of animal telemetry location data. Recent advancements address issues such as temporal autocorrelation and telemetry measurement error, but additional challenges remain. Difficulties introduced by complicated error structures or barriers to animal movement can weaken inference. We propose an approach for obtaining resource selection inference from animal location data that accounts for complicated error structures, movement constraints, and temporally autocorrelated observations. We specify a model for telemetry data observed with error conditional on unobserved true locations that reflects prior knowledge about constraints in the animal movement process. The observed telemetry data are modeled using a flexible distribution that accommodates extreme errors and complicated error structures. Although constraints to movement are often viewed as a nuisance, we use constraints to simultaneously estimate and account for telemetry error. We apply the model to simulated data, showing that it outperforms common ad hoc approaches used when confronted with measurement error and movement constraints. We then apply our framework to an Argos satellite telemetry data set on harbor seals (Phoca vitulina) in the Gulf of Alaska, a species that is constrained to move within the marine environment and adjacent coastlines.
We describe the results of atomistic molecular dynamics simulations of thermal rippling in graphene with the use of a generic harmonic constraint model. The distance and angular constraint constants are calculated directly from the second-generation bond-order interatomic potential that describes carbon binding in graphene. We quantify the thermal rippling process in detail by calculating the overall rippling averages, the normal-normal correlation distributions and the height distributions. In addition, we consider the effect of a dihedral angular constraint, as well as the effect of sample size on the simulated rippling averages. The dynamic corrugation morphologies of simulated graphene samples obtained with the harmonic constraint model at various temperatures are, overall, consistent with those obtained with the bond-order potential and are in qualitative accord with previously reported findings. Given the wide availability of the harmonic constraint model in various molecular mechanics implementations, along with its high computational efficiency, our results indicate a possible use for the presented model in multicomponent dynamic simulations, including atomically thin layers. (paper)
Sundaramoorthi, Ganesh
2012-09-13
This paper presents a novel medical image registration algorithm that explicitly models the physical constraints imposed by objects or sub-structures of objects that have differing material composition and border each other, which is the case in most medical registration applications. Typical medical image registration algorithms ignore these constraints and therefore are not physically viable, and to incorporate these constraints would require prior segmentation of the image into regions of differing material composition, which is a difficult problem in itself. We present a mathematical model and algorithm for incorporating these physical constraints into registration / motion and deformation estimation that does not require a segmentation of different material regions. Our algorithm is a joint estimation of different material regions and the motion/deformation within these regions. Therefore, the segmentation of different material regions is automatically provided in addition to the image registration satisfying the physical constraints. The algorithm identifies differing material regions (sub-structures or objects) as regions where the deformation has different characteristics. We demonstrate the effectiveness of our method on the analysis of cardiac MRI which includes the detection of the left ventricle boundary and its deformation. The experimental results indicate the potential of the algorithm as an assistant tool for the quantitative analysis of cardiac functions in the diagnosis of heart disease.
Deciphering the roles of multiple additives in organocatalyzed Michael additions.
Günler, Z Inci; Companyó, Xavier; Alfonso, Ignacio; Burés, Jordi; Jimeno, Ciril; Pericàs, Miquel A
2016-05-21
The synergistic effects of multiple additives (water and acetic acid) on the asymmetric Michael addition of acetone to nitrostyrene catalyzed by primary amine-thioureas (PAT) were precisely determined. Acetic acid facilitates hydrolysis of the imine intermediates, thus leading to catalytic behavior, and minimizes the formation of the double addition side product. In contrast, water slows down the reaction but minimizes catalyst deactivation, eventually leading to higher final yields. PMID:27128165
A symmetric scalar constraint for loop quantum gravity
Lewandowski, Jerzy
2014-01-01
In the framework of loop quantum gravity, we define a new Hilbert space of states which are solutions of a large number of components of the diffeomorphism constraint. On this Hilbert space, using the methods of Thiemann, we obtain a family of gravitational scalar constraints. They preserve the Hilbert space for every choice of lapse function. Thus adjointness and commutator properties of the constraint can be investigated in a straightforward manner. We show how the space of solutions of the symmetrized constraint can be defined by spectral decomposition, and the Hilbert space of physical states by subsequently fully implementing the diffeomorphism constraint.
Molecular and cellular constraints on proteins
Kortemme, Tanja
Engineering proteins with new sequences, structures and functions has many exciting practical applications, and provides new ways to dissect design principles for function. Recent successes in computational protein design provide a cause for optimism. Yet many functions are currently too complex to engineer predictively, and successful design of new biological activities also requires an understanding of the functional pressures acting on proteins in the context of cells and organisms. I will present two vignettes describing our progress with dissecting both molecular and cellular constraints on protein function. In the first, we characterized the cost and benefit of protein production upon sequence perturbations in a classic system for gene regulation, the lac operon. Our results were unexpected in light of the common assumption that the dominant fitness costs are due to protein expression. Instead, we discovered a direct linear relationship between cost and lacpermease activity, not protein or mRNA production. The magnitude of the cost of permease activity, relative to protein production, has consequences for regulation. Our model predicts an advantage of direct regulation of protein activity (not just expression), providing a new explanation for the long-known mechanism of ``inducer exclusion'' that inhibits transport through the permease. Similar pressures and cost/benefit tradeoffs may be key to engineering synthetic systems with improved fitness. In the second vignette, I will describe our recent efforts to develop computational approaches that predict protein sequences consistent with multiple functional conformations. We expect such ``multi-constraint'' models to improve predictions of functional sequences determined by deep mutational scanning in bacteria, to provide insights into how the balance between functional conformations shapes sequence space, and to highlight molecular and cellular constraints that cannot be captured by the model.
Electroweak constraints on warped geometry in five dimensions and beyond
Archer, Paul R.; Huber, Stephan J.
2010-10-01
Here we consider the tree level corrections to electroweak (EW) observables from standard model (SM) particles propagating in generic warped extra dimensions. The scale of these corrections is found to be dominated by three parameters, the Kaluza-Klein (KK) mass scale, the relative coupling of the KK gauge fields to the Higgs and the relative coupling of the KK gauge fields to fermion zero modes. It is found that 5D spaces that resolve the hierarchy problem through warping typically have large gauge-Higgs coupling. It is also found in D> 5 where the additional dimensions are warped the relative gauge-Higgs coupling scales as a function of the warp factor. If the warp factor of the additional spaces is contracting towards the IR brane, both the relative gauge-Higgs coupling and resulting EW corrections will be large. Conversely EW constraints could be reduced by finding a space where the additional dimension’s warp factor is increasing towards the IR brane. We demonstrate that the Klebanov Strassler solution belongs to the former of these possibilities.
Maximum Entropy method with non-linear moment constraints: challenges
Grendar, M
2003-01-01
Traditionally, the Method of (Shannon-Kullback's) Relative Entropy Maximization (REM) is considered with linear moment constraints. In this work, the method is studied under frequency moment constraints which are non-linear in probabilities. The constraints challenge some justifications of REM since a) axiomatic systems are developed for classical linear moment constraints, b) the feasible set of distributions which is defined by frequency moment constraints admits several entropy maximizing distributions (I-projections), hence probabilistic justification of REM via Conditioned Weak Law of Large Numbers cannot be invoked. However, REM is not left completely unjustified in this setting, since Entropy Concentration Theorem and Maximum Probability Theorem can be applied. Maximum Renyi-Tsallis' entropy method (maxTent) enters this work because of non-linearity of X-frequency moment constraints which are used in Non-extensive Thermodynamics. It is shown here that under X-frequency moment constraints maxTent distri...
Data Driven Constraints for the SVM
Darkner, Sune; Clemmensen, Line Katrine Harder
2012-01-01
We propose a generalized data driven constraint for support vector machines exemplified by classification of paired observations in general and specifically on the human ear canal. This is particularly interesting in dynamic cases such as tissue movement or pathologies developing over time. Assum...... classifier solution, compared to the SVM i.e. reduces variance and improves classification rates. We present a quantitative measure of the information level contained in the pairing and test the method on simulated as well as a high-dimensional paired data set of ear-canal surfaces....
Constraints on Gauge Field Production during Inflation
Nurmi, Sami; Sloth, Martin Snoager
2014-01-01
In order to gain new insights into the gauge field couplings in the early universe, we consider the constraints on gauge field production during inflation imposed by requiring that their effect on the CMB anisotropies are subdominant. In particular, we calculate systematically the bispectrum of the...... primordial curvature perturbation induced by the presence of vector gauge fields during inflation. Using a model independent parametrization in terms of magnetic non-linearity parameters, we calculate for the first time the contribution to the bispectrum from the cross correlation between the inflaton and...
MODELING DATA INTEGRITY UNDER STOCHASTIC LINEAR CONSTRAINTS
Lee-Pin Shing
2015-06-01
Full Text Available The most commonly used data integrity models today are Bibba, Wilson-Clark and Chinese models. These models are designed for both data integrity protection and confidentiality. Many optimization problems are related to linear programming. In practice, these variables involved are probabilistic. This paper proposes a data integrity model based on data anomalies assuming data are under stochastic linear constraints. An algorithm is constructed using the simplex method to find confidence intervals for the problem solutions. In the end the results from Monte Carlo simulation are compared with those from simplex method.
Intelligence Constraints on Terrorist Network Plots
Woo, Gordon
Since 9/11, the western intelligence and law enforcement services have managed to interdict the great majority of planned attacks against their home countries. Network analysis shows that there are important intelligence constraints on the number and complexity of terrorist plots. If two many terrorists are involved in plots at a given time, a tipping point is reached whereby it becomes progressively easier for the dots to be joined and for the conspirators to be arrested, and for the aggregate evidence to secure convictions. Implications of this analysis are presented for the campaign to win hearts and minds.
Generalized gluing for Einstein constraint equations
Mazzieri, L.
2009-01-01
In this paper we construct a family of new (topologically distinct) solutions to the Einstein constraint equations by performing the generalized connected sum (or fiber sum) of two known compact m-dimensional constant mean curvature solutions (M-1, (g1), Pi 1) and (M-2, (g2), Pi(2)) along a common isometrically embedded k-dimensional sub-manifold (K, gK). Away from the gluing locus the metric and the second fundamental form of the new solutions can be chosen as close as desired to the ones of...
Strong constraint on ever-present Λ
We show that the causal-set approach to creating an ever-present cosmological 'constant' in the expanding universe is strongly constrained by the isotropy of the microwave background. Fluctuations generated by stochastic lambda generation which are consistent with COBE and WMAP observations are far too small to dominate the expansion dynamics at z<1000 and so cannot explain the observed late-time acceleration of the universe. We also discuss other observational constraints from the power spectrum of galaxy clustering and show that the theoretical possibility of ever-present lambda arises only in 3+1 dimensional space-times
Cosmological Constraints on a Dynamical Electron Mass
Barrow, J D; Barrow, John D; Magueijo, Joao
2005-01-01
Motivated by recent astrophysical observations of quasar absorption systems, we formulate a simple theory where the electron to proton mass ratio $\\mu =m_{e}/m_{p}$ is allowed to vary in space-time. In such a minimal theory only the electron mass varies, with $\\alpha $ and $m_{p}$ kept constant. We find that changes will be driven by any asymmetry in the electron-positron number density after the electron mass threshold is crossed. Particle production in this scenario is negligible. The constraints imposed by recent observations are very weak, due to the low mass density in electrons.
Black hole entropy, universality, and horizon constraints
To ask a question about a black hole in quantum gravity, one must restrict initial or boundary data to ensure that a black hole is actually present. For two-dimensional dilaton gravity, and probably a much wider class of theories, I show that the imposition of a 'stretched horizon' constraint modifies the algebra of symmetries at the horizon, allowing the use of conformal field theory techniques to determine the asymptotic density of states. The result reproduces the Bekenstein-Hawking entropy without any need for detailed assumptions about the microscopic theory. Horizon symmetries may thus offer an answer to the problem of universality of black hole entropy
The effect of constraints on plastic deformation
Paidar, Václav
Warrendale : Materials Research Society, 2007 - (Wiezorek, J.; Fu, C.; Takeyama, M.; Clemens, H.), II02/05/1-II02/05/6 ISBN 978-1-55899-937-4. - (MRS Proceedings. 980). [Advanced Intermetallic-Based Alloys. Boston (US), 27.11.2006-01.12.2006] R&D Projects: GA AV ČR IAA1041302; GA ČR GA202/04/2016 Institutional research plan: CEZ:AV0Z10100520 Keywords : deformation constraints * TiAl Subject RIV: BM - Solid Matter Physics ; Magnetism
Mission Implementation Constraints on Planetary Muon Radiography
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)
Ghost imaging lidar via sparsity constraints
Zhao, Chengqiang; Gong, Wenlin; Chen, Mingliang; Li, Enrong; Wang, Hui; Xu, Wendong; Han, Shensheng
2012-01-01
For remote sensing, high-resolution imaging techniques are helpful to catch more characteristic information of the target. We extend pseudo-thermal light ghost imaging to the area of remote imaging and propose a ghost imaging lidar system. For the first time, we demonstrate experimentally that the real-space image of a target at about 1.0 km range with 20 mm resolution is achieved by ghost imaging via sparsity constraints (GISC) technique. The characters of GISC technique compared to the exis...
Soft Budget Constraints in Professional Football
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...
Ghost imaging lidar via sparsity constraints
Zhao, Chengqiang; Chen, Mingliang; Li, Enrong; Wang, Hui; Xu, Wendong; Han, Shensheng
2012-01-01
For remote sensing, high-resolution imaging techniques are helpful to catch more characteristic information of the target. We extend pseudo-thermal light ghost imaging to the area of remote imaging and propose a ghost imaging lidar system. For the first time, we demonstrate experimentally that the real-space image of a target at about 1.0 km range with 20 mm resolution is achieved by ghost imaging via sparsity constraints (GISC) technique. The characters of GISC technique compared to the existing lidar systems are also discussed.
Complexity of valued constraint satisfaction problems
Živný, Stanislav
2012-01-01
The topic of this book is the following optimisation problem: given a set of discrete variables and a set of functions, each depending on a subset of the variables, minimise the sum of the functions over all variables. This fundamental research problem has been studied within several different contexts of discrete mathematics, computer science and artificial intelligence under different names: Min-Sum problems, MAP inference in Markov random fields (MRFs) and conditional random fields (CRFs), Gibbs energy minimisation, valued constraint satisfaction problems (VCSPs), and, for two-state variabl
Gathering algorithms on paths under interference constraints
Bermond, Jean-Claude; Correa, Ricardo; Yu, Min-Li
2006-01-01
International audience We study the problem of gathering information from the nodes of a multi-hop radio network into a pre-determined destination node under interference constraints which are modeled by an integer d 1, so that any node within distance d of a sender cannot receive calls from any other sender. A set of calls which do not interfere with each other is referred to as a round. We give algorithms and lower bounds on the minimum number of rounds for this problem, when the network...
Low energy constraints and scalar leptoquarks⋆
Fajfer Svjetlana
2014-01-01
Full Text Available The presence of a colored weak doublet scalar state with mass below 1 TeV can provide an explanation of the observed branching ratios in B → D(∗τντ decays. Constraints coming from Z → bb̄, muon g − 2, lepton flavor violating decays are derived. The colored scalar is accommodated within 45 representation of SU(5 group of unification. We show that presence of color scalar can improve mass relations in the up-type quark sector mass. Impact of the colored scalar embedding in 45-dimensional representation of SU(5 on low-energy phenomenology is also presented.
Detecting Cliques Using Degree and Connectivity Constraints
Abhay Avinash Bhamaikar
2012-03-01
Full Text Available In graph mining determining clique is np complete problem. This paper introduces pruning strategies, by which linear time algorithm for detecting clique is obtained. Clique determination is widely applicable in social network analysis. In social network analysis cliques signifies that each person in the network knows every other person in the group. Here pruning is done using edge connectivity and degree constraints. Initially the graph (g is checked for a bridge, if it is detected, then graph (g is disconnected. Then minimum and maximum degree criteria are used to determine a clique. The algorithm also has wide application in bioinformatics.
Detecting Cliques Using Degree and Connectivity Constraints
Abhay Avinash Bhamaikar
2012-09-01
Full Text Available In graph mining determining clique is np complete problem. This paper introduces pruning strategies, by which linear time algorithm for detecting clique is obtained. Clique determination is widely applicable in social network analysis. In social network analysis cliques signifies that each person in the network knows every other person in the group. Here pruning is done using edge connectivity and degree constraints. Initially the graph (g is checked for a bridge, if it is detected, then graph (g is disconnected. Then minimum and maximum degree criteria are used to determine a clique. The algorithm also has wide application in bioinformatics.
Variational calculus with constraints on general algebroids
Variational calculus on a vector bundle E equipped with a structure of a general algebroid is developed, together with the corresponding analogs of Euler-Lagrange equations. Constrained systems are introduced in the variational and geometrical settings. The constrained Euler-Lagrange equations are derived for analogs of holonomic, vakonomic and nonholonomic constraints. This general model covers the majority of first-order Lagrangian systems which are present in the literature and reduces to the standard variational calculus and the Euler-Lagrange equations in classical mechanics for E = TM
Constraints on reusability of learning objects
May, Michael; Hussmann, Peter Munkebo; Jensen, Anne Skov; Rootzen, Helle; Markvorsen, Steen; Schmidt, Karsten; Skårhøj, Kasper; Enemark, Søren
objects have been proclaimed as important elements in e-learning for a long time, and there are good reasons to believe in the benefits of interactive multimedia as well as flexible and modular learning objects. Nevertheless the use and reuse of learning objects on a large scale seems to be a slow success....... 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....
How long do external capital constraints matter?
Stucki, Tobias
2009-01-01
Start-ups mostly have only limited internal financing. Post-entry performance should thus strongly depend on the availability of new external capital. In this study we analyze the impact of financial constraints on the performance of Swiss start-ups. Since we use cohort data, we have for some start-ups data at different points in time. This allows us to analyze whether the effect of the availability of external capital on firm performance changes with increasing age of the firms. To measure t...
Constrained Microaggregation: Adding Constraints for Data Editing
Vicenc Torra
2008-08-01
Full Text Available Privacy preserving data mining and statistical disclosure control have introduced several methods for data perturbation that can be used for ensuring the privacy of data respondents. Such methods, as rank swapping and microaggregation, perturbate the data introducing some kind of noise. Nevertheless, it is usual that data are edited with care after collection to remove inconsistencies, and such perturbation might cause the introduction of new inconsistencies to them. In this paper we study the development of methods for microaggregation that avoid the introduction of such inconsistencies. That is, methods that ensure the protected data to satisfy a set of given constraints.
AGN outflow feedback: Constraints from variability
Detmers, R G
2009-01-01
We present an overview on how variability can be used to constrain the location of the ionized outflow in nearby Active Galactic Nuclei using high-resolution X-ray spectroscopy. Without these constraints on the location of the outflow, the kinetic luminosity and mass loss rate can not be determined. We focus on the Seyfert 1 galaxy NGC 5548, which is arguably the best studied AGN on a timescale of 10 years. Our results show that frequent observations combined with long term monitoring, such as with the \\textit{Rossi X-ray Timing Explorer (RXTE)} satellite, are crucial to investigate the effects of these outflows on their surroundings.
Gamma ray constraints on decaying dark matter
Cirelli, M.; Moulin, E.; Panci, P.;
2012-01-01
We derive new bounds on decaying dark matter from the gamma ray measurements of (i) the isotropic residual (extragalactic) background by Fermi and (ii) the Fornax galaxy cluster by H.E.S.S. We find that those from (i) are among the most stringent constraints currently available, for a large range...... of dark matter masses and a variety of decay modes, excluding half-lives up to similar to 10(26) to few 10(27) seconds. In particular, they rule out the interpretation in terms of decaying dark matter of the e(+/-) spectral features in PAMELA, Fermi and H.E.S.S., unless very conservative choices...
MatrixPlot: visualizing sequence constraints
Gorodkin, Jan; Stærfeldt, Hans Henrik; Lund, Ole;
1999-01-01
MatrixPlot: visualizing sequence constraints. Sub-title Abstract Summary : MatrixPlot is a program for making high-quality matrix plots, such as mutual information plots of sequence alignments and distance matrices of sequences with known three-dimensional coordinates. The user can add information...... about the sequences (e.g. a sequence logo profile) along the edges of the plot, as well as zoom in on any region in the plot. Availability : MatrixPlot can be obtained on request, and can also be accessed online at http://www. cbs.dtu.dk/services/MatrixPlot. Contact : gorodkin@cbs.dtu.dk...
Additive Manufacturing for Large Products
Leirvåg, Roar Nelissen
2013-01-01
This thesis researches the possibility and feasibility of applying additive manufacturing technology in the manufacturing of propellers. The thesis concerns the production at the foundry Oshaug Metall AS. Their products consist of propellers and other large products cast in Nickel-Aluminium Bronze. This report looks at three approaches and applications for additive manufacturing at the foundry. These are additively manufactured pattern, sand mold and end metal parts. The available \\emph{State...
Babbush, Ryan; O'Gorman, Bryan; Macready, William; Aspuru-Guzik, Alán
2012-01-01
Optimization problems associated with the interaction of linked particles are at the heart of polymer science, protein folding and other important problems in the physical sciences. In this review we explain how to recast these problems as constraint satisfaction problems such as linear programming, maximum satisfiability, and pseudo-boolean optimization. By encoding problems this way, one can leverage substantial insight and powerful solvers from the computer science community which studies constraint programming for diverse applications such as logistics, scheduling, artificial intelligence, and circuit design. We demonstrate how to constrain and embed lattice heteropolymer problems using several strategies. Each strikes a unique balance between number of constraints, complexity of constraints, and number of variables. In addition, each strategy has distinct advantages and disadvantages depending on problem size and available resources. Finally, we show how to reduce the locality of couplings in these energ...
Evaluation of uranium resources. Problems and constraints
Growing awareness that the era of cheap energy is over has led to current efforts by governments and international organizations to examine the question of the adequacy of energy resources on a global scale. Despite the relative success of the NEA and the IAEA efforts in the study of world uranium supply, there is a need for such studies to become still more comprehensive and broader in scope. A basic problem exists with respect to the lack of a universally accepted set of resource terms by which to classify resource estimates once they are made. Often voids exist in international assessments because of insufficient data with respect to known resources and occasionally because of a lack of expertise to make the required estimates. With respect to the assessment of undiscovered uranium resources, major constraints are the relatively embryonic state of methodology for assessment of undiscovered resources and the fact that the inventory of basic geology, geochemical, and geophysical data is either incomplete or non-existent in many parts of the world. Finally, once resource estimates are made, there is often an unclear understanding about when and at what rate the resources can be made available. Hopefully, current efforts will lead to a solution to some of the principal problems and constraints which may be impeding progress toward an expansion and improvement of world uranium resource assessments. (author)
Legal, ethical,and economic constraints
This paper considers the legal, ethical, and economic constraints to developing a comprehensive knowledge of the biological effects of ionizing radiation. These constraints are not fixed and immutable; rather they are determined by the political process. Political issues cannot be evaded. The basic objective of developing a comprehensive knowledge about the biological effects of ionizing radiation exists as an objective not only because we wish to add to the store of human knowledge but also because we have important use for that knowledge. It will assist our decision-makers to make choices that affect us all. These choices require both hard factual information and application of political judgment. Research supplies some of the hard factual information and should be as free as possible from political influence in its execution. At the same time, the political choices that must be made influence the direction and nature of the research program as a whole. Similarly, the legal, ethical, and economic factors that constrain our ability to expand knowledge through research reflect a judgment by political agents that values other than expansion of knowledge should be recognized and given effect
Sensor Localization from Distance and Orientation Constraints.
Porta, Josep M; Rull, Aleix; Thomas, Federico
2016-01-01
The sensor localization problem can be formalized using distance and orientation constraints, typically in 3D. Local methods can be used to refine an initial location estimation, but in many cases such estimation is not available and a method able to determine all the feasible solutions from scratch is necessary. Unfortunately, existing methods able to find all the solutions in distance space can not take into account orientations, or they can only deal with one- or two-dimensional problems and their extension to 3D is troublesome. This paper presents a method that addresses these issues. The proposed approach iteratively projects the problem to decrease its dimension, then reduces the ranges of the variable distances, and back-projects the result to the original dimension, to obtain a tighter approximation of the feasible sensor locations. This paper extends previous works introducing accurate range reduction procedures which effectively integrate the orientation constraints. The mutual localization of a fleet of robots carrying sensors and the position analysis of a sensor moved by a parallel manipulator are used to validate the approach. PMID:27428977
LHC dijet constraints on double beta decay
Helo, J C
2015-01-01
We use LHC dijet data to derive constraints on neutrinoless double beta decay. Upper limits on cross sections for the production of "exotic" resonances, such as a right-handed W boson or a diquark, can be converted into lower limits on the double beta decay half-life for fixed choices of other parameters. Constraints derived from run-I data are already surprisingly strong and complementary to results from searches using same-sign dileptons plus jets. For the case of the left-right symmetric model, in case no new resonance is found in future runs of the LHC and assuming $g_L=g_R$, we estimate a lower limit on the double beta decay half-live larger than $10^{27}$ ys can be derived from future dijet data, except in the window of relatively light right-handed neutrino masses in the range $0.5$ MeV to $50$ GeV. Part of this mass window will be tested in the upcoming SHiP experiment. We also discuss current and future limits on possible scalar diquark contributions to double beta decay that can be derived from dije...
Stochastic population dynamics under resource constraints
Gavane, Ajinkya S.; Nigam, Rahul
2016-06-01
This paper investigates the population growth of a certain species in which every generation reproduces thrice over a period of predefined time, under certain constraints of resources needed for survival of population. We study the survival period of a species by randomizing the reproduction probabilities within a window at same predefined ages and the resources are being produced by the working force of the population at a variable rate. This randomness in the reproduction rate makes the population growth stochastic in nature and one cannot predict the exact form of evolution. Hence we study the growth by running simulations for such a population and taking an ensemble averaged over 500 to 5000 such simulations as per the need. While the population reproduces in a stochastic manner, we have implemented a constraint on the amount of resources available for the population. This is important to make the simulations more realistic. The rate of resource production then is tuned to find the rate which suits the survival of the species. We also compute the mean life time of the species corresponding to different resource production rate. Study for these outcomes in the parameter space defined by the reproduction probabilities and rate of resource production is carried out.
Sensor Localization from Distance and Orientation Constraints
Porta, Josep M.; Rull, Aleix; Thomas, Federico
2016-01-01
The sensor localization problem can be formalized using distance and orientation constraints, typically in 3D. Local methods can be used to refine an initial location estimation, but in many cases such estimation is not available and a method able to determine all the feasible solutions from scratch is necessary. Unfortunately, existing methods able to find all the solutions in distance space can not take into account orientations, or they can only deal with one- or two-dimensional problems and their extension to 3D is troublesome. This paper presents a method that addresses these issues. The proposed approach iteratively projects the problem to decrease its dimension, then reduces the ranges of the variable distances, and back-projects the result to the original dimension, to obtain a tighter approximation of the feasible sensor locations. This paper extends previous works introducing accurate range reduction procedures which effectively integrate the orientation constraints. The mutual localization of a fleet of robots carrying sensors and the position analysis of a sensor moved by a parallel manipulator are used to validate the approach. PMID:27428977
Approximation Schemes for Scheduling with Availability Constraints
Fu, Bin; Huo, Yumei; Zhao, Hairong
We investigate the problems of scheduling n weighted jobs to m identical machines with availability constraints. We consider two different models of availability constraints: the preventive model where the unavailability is due to preventive machine maintenance, and the fixed job model where the unavailability is due to a priori assignment of some of the n jobs to certain machines at certain times. Both models have applications such as turnaround scheduling or overlay computing. In both models, the objective is to minimize the total weighted completion time. We assume that m is a constant, and the jobs are non-resumable. For the preventive model, it has been shown that there is no approximation algorithm if all machines have unavailable intervals even when w i = p i for all jobs. In this paper, we assume there is one machine permanently available and the processing time of each job is equal to its weight for all jobs. We develop the first PTAS when there are constant number of unavailable intervals. One main feature of our algorithm is that the classification of large and small jobs is with respect to each individual interval, thus not fixed. This classification allows us (1) to enumerate the assignments of large jobs efficiently; (2) and to move small jobs around without increasing the objective value too much, and thus derive our PTAS. Then we show that there is no FPTAS in this case unless P = NP.
Astrophysical and cosmological constraints on supersymmetric theories
We summarize the astrophysical and cosmological constraints on theories in which a global supersymmetry remains unbroken down to an energy scale of the order of TeV. The emission of Goldstinos (and possibly photinos) from red giant stars constrain ν (the scale of supersymmetry breaking) to be greater than 0(50 GeV). If ν is 0(1 TeV), then it follows from big bang nucleo-synthesis that at least one of the following particles must be more massive than 0(10 MeV): νsub(tau), the photino, or the Goldstino. If ν is greater than 0(10 TeV), then the big bang nucleosynthesis constraints are much less restritive. The mass density contributed by relic photinos and the contribution of photons from their decays to various diffuse photon backgrounds restrict the photino mass to be either greater than 0(10 MeV) or less than 0(200 eV)
Cosmological Constraints on Higgs-Dilaton Inflation
Trashorras, Manuel; Garcia-Bellido, Juan
2016-01-01
We test the viability of the Higgs-Dilaton Model (HDM) compared to the cosmological constant ($\\Lambda$CDM) and evolving dark energy ($w_0 w_a$CDM) models, by using the latest cosmological data that includes the Cosmic Microwave Background temperature, polarization and lensing data from the Planck satellite (2015 release), the BICEP and Keck Array experiments, the Type Ia supernovae from the JLA catalog, the Baryon Acoustic Oscillations and finally, the Weak Lensing data from the CFHTLenS survey. We find that the values of all cosmological parameters allowed by the Higgs-Dilaton model Inflation are well within the \\textit{Planck 15} constraints. In particular, we have that $w_0 = -1.0001^{+0.0072}_{-0.0074}$, $w_a = 0.00^{+0.15}_{-0.16}$, $n_s = 0.9693^{+0.0083}_{-0.0082}$, $\\alpha_s = -0.001^{+0.013}_{-0.014}$ and $r_{0.05} = 0.0025^{+0.0017}_{-0.0016}$ (95\\%C.L.). We also place new stringent constraints on the couplings of the Higgs-Dilaton model and we find that $\\xi_\\chi < 0.00328$ and $\\xi_h/\\sqrt{\\la...
Curvature constraints from large scale structure
Di Dio, Enea; Montanari, Francesco; Raccanelli, Alvise; Durrer, Ruth; Kamionkowski, Marc; Lesgourgues, Julien
2016-06-01
We modified the CLASS code in order to include relativistic galaxy number counts in spatially curved geometries; we present the formalism and study the effect of relativistic corrections on spatial curvature. The new version of the code is now publicly available. Using a Fisher matrix analysis, we investigate how measurements of the spatial curvature parameter ΩK with future galaxy surveys are affected by relativistic effects, which influence observations of the large scale galaxy distribution. These effects include contributions from cosmic magnification, Doppler terms and terms involving the gravitational potential. As an application, we consider angle and redshift dependent power spectra, which are especially well suited for model independent cosmological constraints. We compute our results for a representative deep, wide and spectroscopic survey, and our results show the impact of relativistic corrections on spatial curvature parameter estimation. We show that constraints on the curvature parameter may be strongly biased if, in particular, cosmic magnification is not included in the analysis. Other relativistic effects turn out to be subdominant in the studied configuration. We analyze how the shift in the estimated best-fit value for the curvature and other cosmological parameters depends on the magnification bias parameter, and find that significant biases are to be expected if this term is not properly considered in the analysis.
Emerging carbon constraints for corporate risk management
While discussions about global sustainability challenges abound, the financial risks that they incur, albeit important, have received less attention. We suggest that corporate risk assessments should include sustainability-related aspects, especially with relation to the natural environment, and encompass the flux of critical materials within a company's value chain. Such a comprehensive risk assessment takes into account input- as well as output-related factors. With this paper, we focus on the flux of carbon and define carbon constraints that emerge due to the disposition of fossil fuels in the input dimension and due to direct and indirect climate change effects in the output dimension. We review the literature regarding the financial consequences of carbon constraints on the macroeconomic, sector, and company level. We conclude that: a) financial consequences seem to be asymmetrically distributed between and within sectors, b) the individual risk exposure of companies depends on the intensity of and dependency on carbon-based materials and energy, and c) financial markets have only started to incorporate these aspects in their valuations. This paper ends with recommendations on how to incorporate our results in an integrated carbon risk management framework. (author)
Density measures and additive property
Kunisada, Ryoichi
2015-01-01
We deal with finitely additive measures defined on all subsets of natural numbers which extend the asymptotic density (density measures). We consider a class of density measures which are constructed from free ultrafilters on natural numbers and study a certain additivity property of such density measures.
Color Addition and Subtraction Apps
Ruiz, Frances; Ruiz, Michael J.
2015-01-01
Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step…
Additive interaction in survival analysis
Rod, Naja Hulvej; Lange, Theis; Andersen, Ingelise;
2012-01-01
It is a widely held belief in public health and clinical decision-making that interventions or preventive strategies should be aimed at patients or population subgroups where most cases could potentially be prevented. To identify such subgroups, deviation from additivity of absolute effects is the...... relevant measure of interest. Multiplicative survival models, such as the Cox proportional hazards model, are often used to estimate the association between exposure and risk of disease in prospective studies. In Cox models, deviations from additivity have usually been assessed by surrogate measures of...... additive interaction derived from multiplicative models-an approach that is both counter-intuitive and sometimes invalid. This paper presents a straightforward and intuitive way of assessing deviation from additivity of effects in survival analysis by use of the additive hazards model. The model directly...
Additional disulfide bonds in insulin
Vinther, Tine N; Pettersson, Ingrid; Huus, Kasper;
2015-01-01
-chain is flexible and can adapt multiple conformations. We examined how well disulfide bond predictions algorithms could identify disulfide bonds in this region of insulin. In order to identify stable insulin analogues with additional disulfide bonds, which could be expressed, the Cβ cut-off distance had...... higher yields in comparison to analogues with additional disulfide bonds that were more difficult to predict. In contrast, addition of the fourth disulfide bond rendered all analogues resistant to fibrillation under stress conditions and all stable analogues bound to the insulin receptor with picomolar...... predicts four additional four disulfide insulin analogues which could be expressed. Although the location of the additional disulfide bonds is only slightly shifted, this shift impacts both stability and activity of the resulting insulin analogues....
Statistical shape fluctuations can be calculated with two alternative assumptions: (a) the temperature remains constant as the shape fluctuates, or (b) the energy remains constant as the shape fluctuates. These two possibilities are compared for a simple model, the Landau theory, and the finite-temperature HFB cranking theory. Average electric quadrupole moments are compared for these two constraints. (orig.)
Gálvez, Jaime; Conejo, Ricardo; Guzmán, Eduardo
2013-01-01
One of the most popular student modeling approaches is Constraint-Based Modeling (CBM). It is an efficient approach that can be easily applied inside an Intelligent Tutoring System (ITS). Even with these characteristics, building new ITSs requires carefully designing the domain model to be taught because different sources of errors could affect…
Relaxation of the lower frit loading constraint for DWPF process control
The lower limit on the frit loading parameter when measurement uncertainty is introduced has impacted DWPF performance during immobilization of Tank 42 Sludge; therefore, any defensible relaxation or omission of this constraint should correspondingly increase DWPF waste loading and efficiency. Waste loading should be increased because the addition of frit is the current remedy for exceeding the lower frit loading constraint. For example, frit was added to DWPF SME Batches 94, 97 and 98 to remedy these batches for low frit loading. Attempts were also made to add frit in addition to the optimum computed to assure the lower frit loading constraint would be satisfied; however, approximately half of the SME Batches produced after Batch 98 have violated the lower frit loading constraint. If the DWPF batches did not have to be remediated and additional frit added because of the lower frit loading limit, then both, the performance of the DWPF process and the waste loading in the glass produced would be increased. Before determining whether or not the lower frit loading limit can be relaxed or omitted, the origin of this and the other constraints related to durability prediction must be examined. The lower limit loading constraint results from the need to make highly durable glass in DWPF. It is required that DWPF demonstrate that the glass produced would have durability that is at least two standard deviations greater than that of the Environmental Assessment (EA) glass. Glass durability cannot be measured in situ, it must be predicted from composition which can be measured. Fortunately, the leaching characteristics of homogeneous waste glasses is strongly related to the total molar free energy of the constituent species. Thus the waste acceptance specification has been translated into a requirement that the total molar free energy associated with the glass composition that would be produced from a DWPF melter feed batch be less than that of the EA glass accounting for