bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new parabolic variational inequality formulation of Signorini's condition for non‐steady seepage problems with complex seepage control systems
Authors: Chen Yifeng , Hu Ran , Zhou Chuangbing , Li Dianqing , Rong Guan 
Published: July 2010

AbstractBy extending Darcy's law to the dry domain above the free surface and specifying the boundary condition on the potential seepage surfaces as Signorini's type, a partial differential equation (PDE) defined in the entire domain of interest is formulated for non‐steady seepage flow problems with free surfaces. A new parabolic variational inequality (PVI) formulation equivalent to the PDE formulation is then proposed, in which the flux part of the complementary condition of Signorini's type in the PDE formulation is transformed into natural boundary condition. Consequently, the singularity at the seepage points is eliminated and the difficulty in selecting the trial functions is significantly reduced. By introducing an adaptive penalized Heaviside function in the finite element analysis, the numerical stability of the discrete PVI formulation is well guaranteed. The proposed approach is validated by the existing laboratory tests with sudden rise and dropdown of water heads, and then applied to capture the non‐steady seepage flow behaviors in a homogeneous rectangular dam with five drainage tunnels during a linear dropdown of upstream water head. The non‐steady seepage flow in the surrounding rocks of the underground powerhouse in the Shuibuya Hydropower Project is further modeled, in which a complex seepage control system is involved. Comparisons with the in situ monitoring data show that the calculation results well illustrate the non‐steady seepage flow process during impounding and the operation of the reservoir as well as the seepage control effects of the drainage hole arrays and drainage tunnels. Copyright © 2010 John Wiley & Sons, Ltd.
Understanding customer satisfaction in opera: first steps toward a model
Authors: Jobst Johanna , Boerner Sabine 
Published: July 2010

Abstract
Despite the frequent call for a strengthened customer orientation in performing arts organizations, no efforts have been made to investigate customer satisfaction in opera so far. The paper aims at filling this gap by suggesting a first integrative model of customer satisfaction in opera. This model integrates insights from both services marketing literature (i.e., general services marketing and performing arts marketing) and performing arts literature (i.e., music perception and theater studies). The model is tested in a field study interviewing 116 visitors of a public German opera house. Results reveal visitors' level of appraisal to be the main antecedent of their satisfaction, followed by their perception of the artistic quality, empathy/identification with the actors on stage, and recall from memory. Furthermore, differences within the audience regarding the relative importance of the antecedents of customer satisfaction in opera are investigated. Using gender and attendance frequency as segmentation variables, only minor differences are found, though. Managerial implications for opera marketing are discussed in conclusion. First, efforts in opera marketing should rather concentrate on the core service quality instead of the peripheral service quality. Second, professional opera companies may attract broader audiences if they focus on the emotional satisfaction of their customers. Third, since only minor and mostly insignificant differences between men and women, and occasional compared to frequent visitors are found, a need for further research to explore alternative segmentation variables in the opera context is identified.
Copyright © 2010 John Wiley & Sons, Ltd.
The impact of case reports relative to other types of publication in palaeopathology
Authors: Mays S. 
Published: July 2010

AbstractDespite repeated calls for palaeopathology to move away from descriptive case reports towards quantitative, problem‐orientated work, case reports still form a high proportion of palaeopathology journal publications. This work assesses, using citation analysis, the impact of the case report relative to that of other types of study in palaeopathology. Results suggest that case studies are cited less often than other types of publication, but that this deficit is less marked than in the clinical sciences where the case report has been effectively marginalised. It is suggested that although a reduction in the proportion of publications in palaeopathology made up of case reports may be desirable, and would be an indication of maturation of the discipline, well‐directed case reports will continue to play a role, albeit a diminishing one, in advancing the field. Copyright © 2010 John Wiley & Sons, Ltd.
Legg–Calvé–Perthes Disease and unifocal eosinophilic granuloma in a visigoth from the Duratón necropolis (Segovia, Spain)
Authors: Herrerín J. , Garralda M. D. 
Published: July 2010

AbstractIndividual number 12, exhumed at the Duratón Visigoth necropolis (Segovia, Spain), was found in a supine position inside a simple fossa without adornments. He was a very robust adult (∼50/60 years) male presenting two pathologies, independently originated and both occurring in a particular anatomical area: the right hip. The first one has been diagnosed as Legg–Calvé–Perthes Disease, and it affects the right femur and the coxal. The femoral head has a diameter that is much greater than usual, with a porous articular surface, no fovea capitis and a marked arthritic secondary growth which is inserted in the femoral neck; the coxal shows a pathological acetabulum larger than the left one, and having osseous borders. The second disease, considered a unifocal eosinophilic granuloma, is in the inner face of the right ilium, and practically occupies the whole iliac fossa. The development of the two pathologies and their probable repercussions on the individual's mobility, on the basis of the study of both the pathological and normal pieces recovered, are discussed. Copyright © 2010 John Wiley & Sons, Ltd.
Optimal control of Markovian queueing systems
Authors: Klein C. F. , Gruver W. A. 
Published: July 2010

AbstractDynamic optimization of queueing systems is treated by optimal control theory. This work is based on modelling the queueing problem as a time‐varying continuous Markov chain. Necessary and sufficient conditions are given for a broad class of problems which include both scalar and Markovian dynamic programming control structures. Continuity of the switching function is used to characterize optimality near the end points of the horizon. Special properties of the model are exploited to ensure the absence of singular subarcs. Numerical results based on the use of a gradient algorithm report the effect of increasing the system capacity, a comparison of scalar versus Markovian dynamic programming controls, and an application to a multiprogrammed computer system.
Adjustment costs and the theory of optimal investment and financing of the firm
Authors: Lin Winston T. 
Published: July 2010

AbstractA dynamic optimal‐control based model that explicitly includes the effects of adjustment costs of investment and financing is presented to analyse the investment and financing decisions of a present value‐maximizing firm. The model is constrained by an equity‐capital formation and a linear homogeneous earnings‐investment possibility function composed of two components: an adjustment‐cost function and an ordinary production function. Pontryagin's maximum principle is used to solve the model. The main results derived from the model include an optimal investment decision rule, an optimal investment‐financing plan, the long‐run equity demand for the firm, and the long‐run behaviour of investment and financing as they are affected by the existence of adjustment costs.
Some basic algebraic relations in the order‐reduction of large‐scale systems by aggregation
Authors: Ying‐Ping Zheng 
Published: July 2010

AbstractIn this paper, we prove conditions for the existence of a full‐rank matrix K which satisfies the aggregation relations (4)–(6). These conditions are convenient for checking and offer some rules for selecting K. Theorem 3 shows the properties of the matrix F in the aggregated model. It is actually a generalization of the important algebraic theorem on the similarity transformation of matrices.
Solution of ill‐conditioned optimality conditions for control of turbo‐alternators
Authors: Shamaly A. , Christensen G. S. , El‐Hawary M. E. 
Published: July 2010

AbstractThe computational solution of the optimality equations for torque and voltage control of a large‐scale turbo‐alternator is considered. The equations are extremely ill‐conditioned as a consequence of the ill‐conditioning of the linearized system model. Our main result is to point out that using the Ricatti equation to estimate the initial values of the Lagrange multipliers renders the equations in a form that can easily be solved as an initial value problem for the non‐linear system.
An Approximation technique for small noise open‐loop control problems
Authors: Holland Charles J. 
Published: July 2010

AbstractFor a class of non‐linear open‐loop stochastic control problems with small additive white noise, an approximation technique to compute an optimal control of fixed structure related to the noise intensity is presented. The method developed here leads to a generalized deterministic linear regulator problem. It has the advantage that approximate optimal controls are obtained simultaneously for all sufficiently small noise levels. A numerical example is presented to illustrate the method.
Security‐level strategies for non‐linear stochastic pursuit‐evasion differential games
Authors: Chompaisal A. , Leondes C. T. 
Published: July 2010

AbstractA first‐order algorithm is developed to solve for the security‐level strategies of differential games without an assumption that a saddle point exists. The inner optimization uses differential dynamic programming together with a convergence control method. The outer optimization uses a gradient method. The application of the algorithm is demonstrated by solving for numerical strategies for a realistic missile‐antimissile pursuit‐evasion problem. Two major advantages for this algorithm are that the initialization requires only a rough estimate of the nominal control and that the Hessian matrix of the Hamiltonian with respect to the control vector is positive (negative) definite for the minimization (maximization) problem only on the optimal path.
The homicidal chauffeur game—a Stochastic Model
Authors: Pachter M. , Yavin Y. 
Published: July 2010

AbstractWe consider a certain stochastic pursuit—evasion problem of the homicidal chauffeur type. Specifically, weshow that, in contrast to the less straightforward swerve manoeuvre employed in the deterministic model, the particularly simple bang‐bang pursuit strategy synthesized here is applicable to a significant range of problem parameters. The strategy of the slower but agile player is also characterized, and its geometric meaning isillustrated.
Optimal advertising for the Nerlove‐Arrow Model under a replenishable budget
Authors: Sethi S. P. , Lee S. C. 
Published: July 2010

AbstractThis paper considers an optimal control problem with two state variables for the dynamics of the Nerlove—Arrow advertising model. The optimal control is the rate of advertising expenditure required to maximize the present value of net profit streams over an infinite horizon subject to a replenishable budget. It is shown that an equilibrium level of advertising exists in all possible cases. It is interesting to note that this level happens to be non‐singular in some cases. Also shown is the optimal transient approach to these equilibrium levels.
Finite‐difference gradients versus error‐quadrature gradients in the solution of parameterized optimal control problems
Authors: Kraft D. 
Published: July 2010

AbstractTwo non‐linear programming algorithms based on the Lagrangian function are compared with respect to their computational efficiency for solving parameterized optimal control problems. If the most efficient, constrained variable metric method together with forward‐difference gradients is used, the formulation and implementation of the adjoint variables can be avoided. This is especially convenient in the design phase of large complex systems.
Computation of nash equilibrium pairs of a stochastic differential game
Authors: Yavin Y. , Reuter G. 
Published: July 2010

AbstractConsider the random motion of two points Me and Mp in an open and bounded domain D0 in the plane. Each of the velocities, u = (u1 u2)T of Me and v = (v1, v2)T of Mp, are perturbed by a corresponding R2‐valued Gaussian white noise. Let A and Dc be two disjoint closed subsets of D0. Suppose that at t = 0, Me is in A and Mp is anywhere in D0. Denote by ℰ1 and ℰ2 the following events: ℰ1 = {Mp intercepts Me in A before Me reaches the set Dc and before either Me or Mp has left D0}, and ℰ2 = {Me reaches the set Dc before being intercepted by Mp, while Mp is in A, and before either Mp or Me has left D0}.The problem dealt with here is to find a pair of velocity strategies (u*, v*) such that, in the sense of a Nash equilibrium point, the probabilities Prob(ℰ1) and Prob(ℰ2) will both be maximized on a given class of velocity strategies (u, v). Sufficient conditions on (u*, v*) are derived which require the existence of a smooth solution (V,Q) to a pair of coupled non‐linear partial differential equations. A finite‐difference scheme for solving these equations is suggested, and two examples are treated in detail.
A Local optimization procedure for a gas compressor station
Authors: Osiadacz A. , Bell D. J. 
Published: July 2010

AbstractThe optimal control of a gas compressor station is required which minimizes the costs of powering the compressors. An algorithm is developed which has a two‐level structure: an optimization level and a control/adjustment level. The former minimizes the engine fuel consumption with the use of measured values of flow through the station together with suction and discharge pressure. The latter level ensures proper operating conditions for the compressors and thereby reduces the cost of maintenance and repairs. The proposed procedure is illustrated by an example, and the results show that the method can lead to a significant saving in fuel consumption.
Suboptimal controller design for active control of circular saw vibrations
Authors: Cho H. S. , Cho Y. J. 
Published: July 2010

AbstractA circular saw in operation can have an instability phenomenon which is characterized by a large amplitude and operation speed‐dependent vibration. In this paper, a method of suppressing such unstable motion is presented. An optimal output feedback control scheme is adopted, and only the output variables available from sensors are used. A truncated vibrational mode model is used to formulate the saw dynamics. This model incorporates the forces due to the actuators. Since the performance of controlling the saw motion depends greatly upon spatial locations of both actuators and sensors, their locations are optimally determined with respect to a prescribed performance index representing the vibrating system energy. A two‐mode simulation of a saw is made to illustrate the effectiveness of the control scheme. The results show that this proposed design method stabilizes the otherwise unstable motion of the saw and also requires a very short controlling time for vibration suppression.
An Optimal control approach to marketing‐production planning
Authors: Abad Prakash L. 
Published: July 2010

AbstractThe problem of finding an optimal advertising and production policy in a firm is analysed using a recently proposed model of a marketing‐production system. First, it is shown that the optimal control problem underlying the proposed model is a partially singular control problem. Then, a reverse‐time parametric solution procedure is designed to determine the optimal advertising and production policy for the proposed model. Finally, it is shown that the results derived from the new model are applicable to problems of capacity expansion in a firm.
Flexible spacecraft attitude measurement and control scheme incorporating state estimation
Authors: Fenton J. , Horton D. , Gill K. F. 
Published: July 2010

AbstractThe design of an attitude measurement and control scheme for a flexible space vehicle is presented. A proposed spacecraft configuration is used to study the performance of an inertial‐optical measurement system incorporating a Kalman filter to obtain the best estimates in the presence of differing noise models. These estimates are used to correct for gyroscope drift and also provide the information necessary to implement optimal attitude control with active damping of the flexural motion.
Optimal control of non‐linear distributed parameter systems by a finite‐element collocation technique
Authors: Rao K. C. , Prabhu S. S. , Mehta S. C. 
Published: July 2010

AbstractA finite‐element collocation technique is proposed for solving non‐linear distributed parameter system (DPS) optimal control problems. On each element, two Gaussian collocation points and Hermite approximation functions are used in the finite‐element collocation technique. The numerical experience for two non‐linear DPS, one involving distributed control and the other involving spatially‐independent control, is reported. Optimal control of DPS can be computed with relatively low‐order models when this finite‐element collocation technique is used.
Time‐optimal control of an overhead crane model
Authors: Manson G. A. 
Published: July 2010

AbstractTime‐optimal solutions for a simple crane model have been arrived at by a number of authors using expensive analogue methods. The method described in this paper also gives time‐optimal solutions but these can be obtained using a very simple microprocessor. These solutions are obtained quickly and inexpensively and thus can be used for comparison with other suboptimal solutions based on more complex and less idealized models. An extension of the method is also outlined which covers certain variants of the simple model.
Time‐scale decoupling and order reduction for linear time‐varying systems
Authors: O'Malley Robert E. , Anderson Leonard R. 
Published: July 2010

AbstractThe class of time‐varying linear systems which are two‐time‐scale on an interval may be decoupled by a transformation of variables into separate subsystems containing the slow and fast dynamic parts. The transformation is obtained by solving a non‐symmetric Riccati differential equation forward in time and a linear matrix differential equation backward in time. Small parameters are identified which measure the strength of the time‐scale separation and the stability of the fast subsystem. As these parameters go to zero, the order of the system is reduced, and a useful approximate solution to the original system is obtained. The transformation is illustrated for examples with strong and weak fast subsystem stability.
Controller design for parameter sensitivity reduction in linear regulators
Authors: Yedavalli Rama Krishna , Skelton Robert E. 
Published: July 2010

AbstractThis paper addresses the problem of parameter sensitivity reduction in linear regulators. It is shown that the minimization of a modified performance index which includes a quadratic term of trajectory sensitivity (state, output, or control) subject to the augmented sensitivity system dynamics causes reduction not only in trajectory sensitivity but also in cost sensitivity. Inclusion of both state sensitivity and control sensitivity terms in the cost functional reduces cost sensitivity and facilitates the unification of two approaches previously treated independently: ‘trajectory sensitivity reduction’ and ‘cost sensitivity reduction’. Two control design methods, one based on a linear formulation and the other on a non‐linear formulation, are given for both deterministic and stochastic systems. The improvement of these methods over existing methods is illustrated by examples.
Optimal Two‐Impulse Transfer Between Specified Terminal States Of Keplerian Orbits
Authors: Jezewski D. J. 
Published: July 2010

AbstractThe integrals of motion for an inverse‐square force field and a necessary condition for optimality are used in a transfer orbit co‐ordinate system to formulate the solution of the optimal two‐impulse transfer between fixed position and velocity vectors on Keplerian orbits. In this co‐ordinate system, the equations reveal two asymptotes that are useful in analysing the solution. It is shown that there are only two real extremals (both minimums) which are separated by an asymptote. An approximate analytic solution is also obtained by ignoring a quadratic term whose coefficient is approximately zero for a large class of orbit transfer problems.
Boost–glide range‐optimal guidance
Authors: Kelley H. J. , Cliff E. M. , Lutze F. H. 
Published: July 2010

AbstractA simple guidance scheme is proposed which approximately optimizes the range of the glide phase of a boost‐glide vehicle's trajectory. The scheme requires only altitude, flight‐path angle, and attitude measurements for implementation. The guidance law provides an attitude command based on the actual flight‐path angle and on a calculated flight‐path angle associated with that of an equilibrium, constant‐dynamic‐pressure, glide of maximum lift‐to‐drag ratio. By proper weighting of these two inputs, an approximately optimal guidance control is realized. Two examples are given which demonstrate the trajectory characteristics for a high‐performance aircraft and for a missile‐type vehicle.
The control of environmental pollution and optimal investment and employment decisions
Authors: Lin Winston T. 
Published: July 2010

AbstractThis paper develops an optimal control model for the firm's decision‐making concerning pollution control spending, employment and investment. The model explicitly considers the impact of adjustment costs of changing the level of the pollution stock and involves three state variables and two control variables. Necessary conditions are derived by the maximum principle. The results include an optimal employment‐investment‐pollution abatement programme, an optimal pollution control decision rule, the equilibrium optimal pollution control and spending plan, and the equilibrium employment‐investment decision.
Relations between frequency‐dependent control and state weighting in LQG problems
Authors: Anderson B. D. O. , Moore J. B. , Mingori D. L. 
Published: July 2010

AbstractThis paper considers the relation between controller designs for the same linear system achieved with two different quadratic performance indices. These indices differ only to the extent that one has frequency weighting on the control whereas the other has the inverse frequency weighting on the state. The feedback controllers are constructed by augmenting the given plant and by solving a modified LQG problem for the augmented system. The main result is that whereas the optimal controls as time functions can be the same, the optimal controllers are different. Filtering results are also obtained.