bluuebunny/crossref_metadata_2025_split huggingface dataset:
The efficient liquid‐phase oxidation of aromatic hydrocarbons by molecular oxygen in the presence of MnCO3
Authors: Gao Jin , Tong Xinli , Li Xiaoqiang , Miao Hong , Xu Jie 
Published: July 2007

AbstractBACKGROUND: The liquid‐phase catalytic oxidation of aromatic hydrocarbons by molecular oxygen is a commercially important process. We consider the MnCO3‐promoted oxidation of toluene to produce benzaldehyde and benzoic acid. In this investigation, toluene was oxidized with 25.0% conversion and 80.8% selectivity with respect to benzoic acid in the presence of MnCO3 under 1.0 MPa of oxygen at 190 °C for 2 h.RESULTS: Moreover, the oxidation of other aromatic hydrocarbons, such as ethylbenzene, p‐xylene, m‐xylene, o‐xylene, and p‐chlorotoluene, were also efficiently promoted by MnCO3.CONCLUSION: It is concluded that an efficient oxidation of aromatic hydrocarbons can be achieved in the presence of MnCO3 under solvent‐free conditions. The catalytically active species are high‐valence Mn generated via the action of MnCO3 with oxygen. Copyright © 2007 Society of Chemical Industry
Optimization of chromium removal by the chromium resistant mutant of the cyanobacterium Anacystis nidulans in a continuous flow bioreactor
Authors: Khattar Jasvir IS , Sarma Tangirala A , Sharma Anuradha 
Published: July 2007

AbstractBACKGROUND: Chromium removal potential of the cyanobacterium Anacystis nidulans and its chromium resistant strain CrrI8 has been optimized. Optimized parameters include biomass load, pH, temperature and dilution rate of the bioreactor.RESULTS: Results show that chromium resistant strain has high EC50 dose for chromium compared to wild strain. Chromium removal potential of both strains is strongly influenced by various factors. Optimized conditions in batch system included pH 6.5, temperature 28 °C, biomass load 150 µg protein mL−1 for 30 µmol L−1 Cr6+ solution. In continuous flow bioreactor at optimum pH (6.5) and temperature (28 °C) at a fixed biomass of 10 mg protein and 30 µmol L−1 Cr6+, metal removal efficiency varied with dilution rate. For A. nidulans continuous flow bioreactor, optimum dilution rate was 0.076 h−1 (64.6 per cent metal removal) while for CrrI8 it was 0.152 h−1 (85.8 per cent metal removal). Operative time of the CrrI8 bioreactor was also more (85 h) compared to A. nidulans bioreactor (45 h).CONCLUSION: Under optimized conditions resistant strain CrrI8 removed more Cr6+ compared to A. nidulans and thus has the potential to be exploited for Cr6+ removal from industrial effluents at large scale. Copyright © 2007 Society of Chemical Industry
Even‐electron ions: a systematic study of the neutral species lost in the dissociation of quasi‐molecular ions
Authors: Levsen Karsten , Schiebel Hans‐Martin , Terlouw Johan K. , Jobst Karl J. , Elend Manfred , Preiß Alfred , Thiele Herbert , Ingendoh Arnd 
Published: July 2007

AbstractThe collision‐induced dissociations of the even‐electron [M + H]+and/or [M − H]−ions of 121 model compounds (mainly small aromatic compounds with one to three functional groups) ionized by electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) have been studied using an ion trap instrument, and the results are compared with the literature data. While some functional groups (such as COOH, COOCH3, SO3H in the negative ion mode, or NO2in both the positive and negative ion modes) generally promote the loss of neutrals that are characteristic as well as specific, other functional groups (such as COOH in the positive ion mode) give rise to the loss of neutrals that are characteristic, but not specific. Finally, functional groups such as OH and NH2in aromatic compounds do not lead to the loss of a neutral that reflects the presence of these substituents. In general, the dissociation of [M + H]+and [M − H]−ions generated from aliphatic compounds or compounds containing an aliphatic moiety obeys the even‐electron rule (loss of a molecule), but deviations from this rule (loss of a radical) are sometimes observed for aromatic compounds, in particular for nitroaromatic compounds. Thermochemical data andab initiocalculations at the CBS‐QB3 level of theory provide an explanation for these exceptions. When comparing the dissociation behaviour of the even‐electron [M + H]+and/or [M − H]−ions (generated by ESI or APCI) with that of the corresponding odd‐electron [M]+ions (generated by electron ionization, EI), three cases may be distinguished: (1) the dissociation of the two ionic species differs completely; (2) the dissociation involves the loss of a common neutral, yielding product ions differing in mass by one Da, or (3) the dissociations lead to a common product ion. Copyright © 2007 John Wiley & Sons, Ltd.
Theoretical and experimental studies on the adsorption behavior of thiophenol on gold nanoparticles
Authors: Li Shujin , Wu Deyin , Xu Xiaoyan , Gu Renao 
Published: July 2007

AbstractFT‐Raman spectra were obtained for thiophenol (TP) and TP on gold nanoparticles. All vibrational fundamentals for the TP molecule are assigned on the basis of the scaled quantum force field procedure. Three model systems are studied and compared for the interactions of TP with the Au atom: (1) TP with a Au atom, C6H5SHAu; (2) TP anion with a Au atom, C6H5S−Au; and (3) TP with a Au atom and subsequent formation of thiophenylate, C6H5SAu. The equilibrium structures and Raman spectra were calculated for the model systems using density functional theory (DFT) with the B3LYP functionals and the mixed basis set 6‐311 + G** (for C, S, H) and LANL2DZ (for Au), and theoretical Raman wavenumbers of C6H5SAu and C6H5S−Au were assigned according to potential energy distributions. The third model system is shown to be preferred over the other two. The calculated binding energies are also shown to support the third model system. It is suggested that a simple model, such as the one used in the present study, is reasonable to describe surface‐enhanced Raman spectroscopy of thiophenol adsorbed on gold nanoparticles. Copyright © 2007 John Wiley & Sons, Ltd.
Metabolism of phthalates in humans
Authors: Frederiksen Hanne , Skakkebaek Niels E. , Andersson Anna‐Maria 
Published: July 2007

AbstractPhthalates are synthetic compounds widely used as plasticisers, solvents and additives in many consumer products. Several animal studies have shown that some phthalates possess endocrine disrupting effects. Some of the effects of phthalates seen in rats are due to testosterone lowering effects on the foetal testis and they are similar to those seen in humans with testicular dysgenesis syndrome. Therefore, exposure of the human foetus and infants to phthalates via maternal exposure is a matter of concern. The metabolic pathways of phthalate metabolites excreted in human urine are partly known for some phthalates, but our knowledge about metabolic distribution in the body and other biological fluids, including breast milk, is limited. Compared to urine, human breast milk contains relatively more of the hydrophobic phthalates, such as di‐n‐butyl phthalate and the longer‐branched, di(2‐ethylhexyl) phthalate (DEHP) and di‐iso‐nonyl phthalate (DiNP); and their monoester metabolites. Urine, however, contains relatively more of the secondary metabolites of DEHP and DiNP, as well as the monoester phthalates of the more short‐branched phthalates. This differential distribution is of special concern as, in particular, the hydrophobic phthalates and their metabolites are shown to have adverse effects following in utero and lactational exposures in animal studies.
The design of dynamic ship positioning control systems using stochastic optimal control theory
Authors: Grimble M. J. , Patton R. J. , Wise D. A. 
Published: July 2007

AbstractThe design of dynamic ship positioning control systems and their associated wave filters is considered. The control problems and the basic components in the system are discussed first. The model of the vessel is then described, since this plays an important role in the design of the Kalman filter which is used to estimate the low frequency motions of the vessel. The model involves both high and low frequency subsystems. The total linearized model for the vessel is represented by state equations, and simulation results are given to illustrate the performance of the Kalman filter. A comparison with a notch filter is also presented.The design of the optimal control system using LQG stochastic control results is considered. The operation of the system under various operating conditions is illustrated. Schemes involving the extended Kalman filter are then described. These enable more realistic non‐linear models of the plant to be employed within the filter. This is shown to be unnecessary in the case of the low frequency ship model. However, the extended filter may be useful to track varying wave conditions (using parameter estimation) as represented in the high frequency model. Two extended filtering schemes are presented for this case.
A time‐optimal drug displacement problem
Authors: Bell D. J. , Katusiime F. 
Published: July 2007

AbstractThe interaction between the two drugs, warfarin and phenylbutazone, is considered through a previously derived model. A minimum time problem, which involves a state constraint is formulated. This problem is investigated both analytically and numerically. The numerical results are obtained by transforming the state constrained problem to one which is singular and then using a conjugate gradient algorithm to obtain approximations to the optimal control. Further approximations to the control, the rate of infusion of phenylbutazone, are made so that the time profile is feasible for practical implementation.
Primer vector theory applied to the linear relative‐motion equations
Authors: Jezewski Donald 
Published: July 2007

AbstractPrimer vector theory is used in analysing a set of linear relative‐motion equations—the Clohessy‐Wiltshire (C/W) equations—to determine the criteria and necessary conditions for an optimal N‐impulse trajectory. Since the state vector for these equations is defined in terms of a linear system of ordinary differential equations, all fundamental relations defining the solution of the state and costate equations and the necessary conditions for optimality can be expressed in terms of elementary functions. The analysis develops the analytical criteria for improving a solution by (1) moving any dependent or independent variable in the initial and/or final orbit, and (2) adding intermediate impulses. If these criteria are violated, the theory establishes a sufficient number of analytical equations. The subsequent satisfaction of these equations will result in the optimal position vectors and times of an N‐impulse trajectory.The solution is examined for the specific boundary conditions of (1) fixed‐end conditions, two‐impulse, and time‐open transfer; (2) an orbit‐to‐orbit transfer; and (3) a generalized rendezvous problem. A sequence of rendezvous problems is solved to illustrate the analysis and the computational procedure.
Large finite horizon and infinite horizon lq‐optimal control problems
Authors: Willems J. L. , Callier F. M. 
Published: July 2007

AbstractIn this paper the relations between the finite horizon optimal control problem with receding horizon and the infinite horizon problem are discussed; the system is assumed to be linear, time‐invariant, and stabilizable. The cost function is quadratic but the output in the integral of the cost function may be undetectable. Control problems with terminal cost and problems with linear terminal state constraints are dealt with. The solution of the infinite horizon problem as well as the limiting behaviour of the solution of the finite horizon problem are derived. A necessary and sufficient condition for equivalence is developed; it is satisfied for the standard linear regulator problem.
Decentralized stochastic adaptive nash games
Authors: Chan Y. M. , Cruz J. B. 
Published: July 2007

AbstractThe optimization of stochastic systems with unknown parameters and multiple decision‐makers or controllers each having his own objective is considered. Two explicit self‐tuning type algorithms are proposed for decentralized stochastic adaptive Nash games under the ‘one‐step‐delay sharing pattern’. The first algorithm is an ad hoc constraint on the policy form, whereas the second one is based on an extension from static Nash game theory. Simulation results on a simplified economic system indicate that these algorithms are capable of stabilizing a system along targeted paths.
Deterministic and stochastic optimization of a dynamic advertising model
Authors: Sethi Suresh P. 
Published: July 2007

AbstractThis paper considers a variation of the Vidale‐Wolfe advertising model for which the maximum value of the objective function and the form of the optimal feedback advertising control are identical in both a deterministic and a stochastic environment. The stochastic environment is due to a white noise disturbance introduced in the deterministic sales‐advertising dynamics.
National welfare versus ‘economic independence’: The case of iran
Authors: Razavi Hossein 
Published: July 2007

AbstractA linear‐quadratic welfare maximization model is formulated to study the trade‐offs between the political desirability and the economic cost of reducing foreign trade. The model is then applied to the case of Iran and a dynamic programming algorithm is employed to calculate the numerical values of the optimal trade policies. The effects of various political attitudes on the trade policies are discussed.
Output feedback pole assignment under system variation
Authors: Lee Gordon K. F. , Godbout Louis F. 
Published: July 2007

AbstractThe design of multivariable control systems using pole assignment has resulted in much research. Owing to system or parameter variation, the initial compensator design for constant conditions may lead to undesirable responses. Hence, it is important to design compensator structures which maintain desired pole locations under such changes.This paper presents a design methodology for output feedback pole assignment when there is system variation. A performance measure is formulated which represents a squared‐error between desired pole locations and the actual pole locations generated via compensation under probabilistic variations. Optimization of this measure requires constructing gradient matrices necessary to obtain the compensator parameters.Both constant output feedback and dynamic compensation are discussed for pole placement, and the unstable Boeing‐Vertol CH‐46 helicopter system is considered to illustrate the design algorithms.
A note on avoidance control
Authors: Leitmann G. , Skowronski J. 
Published: July 2007

AbstractEarlier work has dealt with controls which guarantee that every trajectory of a given dynamical system remains outside (avoids) a prescribed set (anti‐target) for all time. In the present treatment, we permit the intersection of the anti‐target but consider two cases of avoidance: the anti‐target must be avoided during a prescribed time interval (finite‐time avoidance), or the anti‐target must be avoided for all time after some calculable or prescribed time interval (ultimate avoidance). Sufficient conditions are presented for these two kinds of avoidance. The use of these conditions is illustrated by two examples.
Minimum horizontal rotations
Authors: Marchal C. 
Published: July 2007

AbstractThe problem treated here is to rotate a rigid body from one arbitrary angular orientation to another using only rotations about horizontal axes. The total rotation angle is to be minimized. This problem is formulated and solved as an optimal control problem. The solution is both simple and elegant. Examples are provided to illustrate the results. The problem is motivated by the desire to use the Earth's magnetic field for satellite attitude control.
Globally optimal control of self‐adjoint distributed systems
Authors: Meirovitch L. , Silverberg L. M. 
Published: July 2007

AbstractThe partial differential equations of motion for an uncontrolled distributed structure can be transformed into a set of independent modal equations in terms of natural co‐ordinates. It is common practice to design control forces that recouple the modal equations so that the natural co‐ordinates for the open‐loop (uncontrolled) system cease to be natural co‐ordinates for the closed‐loop (controlled) system. This approach is referred to as coupled control. In contrast, the independent modal‐space control method is a natural control method, i.e. natural co‐ordinates for the open‐loop system remain natural co‐ordinates for the closed‐loop system. Moreover, natural control provides a unique and globally optimal closed‐form solution to the linear optimal control problem for the distributed structure. Indeed, discretization is not necessary. The optimal control forces are ideally distributed. The distributed control can be approximated by finite‐dimensional control, a process that does not require truncation of the plant. Two numerical examples are presented.
Quantized control with data compression constraints
Authors: Fischer Thomas R. 
Published: July 2007

AbstractThe linear‐quadratic‐Gaussian problem of quantized control subject to quantized measurements is considered with the measurement and control quantizers formulated as data compression systems. The optimum closed‐loop control is shown to be separable in control law, control quantizer and estimation. However, estimation and measurement quantization are non‐separable. The optimum measurement quantizer is of a differential structure but requires optimum state estimation at both encoder and decoder. A fixed total number of quantization levels should be equally allocated to the measurement and control quantizers, and the quantizer design depends on both the known control law and the solution to the matrix Riccati equation. A suboptimum control structure is developed, and the effect of quantization error on estimation error is shown to be stable.
The determining set in the infinite horizon problem of optimal control
Authors: Stern Lynnell E. 
Published: July 2007

AbstractThis paper will study the adjoint vector in the infinite horizon optimal control problem. The approach used is to translate the adjoint vector, by means of the fundamental solution of the homogeneous variational equation, back to the initial time. Thus, the set of adjoint vectors ‘satisfying the maximum principle’ will be formed at the initial time. This set will be called the ‘determining set’ and will then be used to ascertain conditions of optimality. Properties, applications and an example of the determining set are given.
Gain optimization with non‐linear controls
Authors: Slater G. L. , Kandadai R. D. 
Published: July 2007

AbstractAn algorithm has been developed for the analysis and design of controls for non‐linear systems. The technical approach is to use statistical linearization to model the non‐linear dynamics of a system by a quasi‐Gaussian model. A covariance analysis is performed to determine the behaviour of the dynamical system and a quadratic cost function. Expressions for the cost function and its derivatives are determined so that numerical optimization techniques can be applied to determine optimal feedback laws.The primary application for this paper is centred about the design of controls for nominally linear systems but where the controls are saturated or limited by fixed constraints. The analysis is general, however, and numerical computation requires only that the specific non‐linearity be considered in the analysis.
Design of optimal feedback controllers for minimum eigenvalue sensitivity
Authors: Qiu Haiming , Gourishankar V. G. 
Published: July 2007

AbstractAn iterative method for designing an optimal constant gain feedback controller for a linear system to achieve minimum eigenvalue sensitivity to parameter variations is presented. In addition to assigning eigenvalues to desired locations in the complex plane, one can also assign elements of eigenvectors by this method. This makes it possible to shape the response of the states. Examples to illustrate the effectiveness of this method are included.
The non‐co‐operative solution of a differential game: Advertising versus pricing
Authors: Gaugusch Julius 
Published: July 2007

AbstractThe purpose of this paper is to compare the effectiveness of advertising campaigns with a low‐price policy. A two‐person non‐zero‐sum differential game is considered in which two firms maximizing their profits are observed. One firm uses advertising expenditures as its control variable and keeps price fixed, whereas the other uses price as a control variable and does not advertise. A system of two differential equations for the Nash solution path is derived. Analysis of the phase diagram yields qualitative results on the structure of the optimal solutions.
An application of hierarchical optimization in calibration of large‐scale water networks
Authors: Coulbeck B. 
Published: July 2007

AbstractThe paper develops a new method for optimized calibration of large‐scale non‐linear water networks. Calibration requirements are first discussed with relevance to the limited monitored operating data, the ill‐defined network parameters and the potential benefits of more accurate network simulations for analysis and control purposes. A formulation is then made which incorporates simultaneous adjustment of network physical parameters and related operational data in order to force agreement between measured and simulated variables. The system non‐linear response is represented by a high‐dimensional set of linear‐equations relating controllable adjustment parameters to the observed discrepancies in operating conditions. Quadratic performance indices, with optional user‐defined weighting factors, are shown to be most appropriate for the control variables. Use of a hierarchical optimization technique permits a solution to be obtained to the problem of high dimensionality with constrained controls and variable performance factors. Application of the scheme to a test distribution system leads to optimal adjustment of all the permitted variables to give the best overall solution for the available measurements. An important practical feature is the ease with which engineering experience can be incorporated to yield alternative solutions.
A method of design against vibration resonance of beams and shafts
Authors: Bendsøe Martin P. , Olhoff Niels 
Published: July 2007

AbstractWe consider problems of designing vibrating beams or rotating shafts to obtain as large gaps as possible in the spectra of natural frequencies or critical speeds in order to avoid resonance or whirling instability for a wide range of external excitation frequencies or service speeds. Governing equations for such design problems are derived by variational analysis of a bound formulation, and a numerical solution to an example problem is discussed.
A homotopy algorithm for solving coupled riccati equations
Authors: Mariton M. , Bertrand P. 
Published: July 2007

AbstractMany applications of optimization theory require the solution of a set of coupled Riccati equations. In multi‐person‐games problems, the players' decision for the Nash equilibrium depend on Riccati equations coupled through their quadratic terms. Another example is provided by linear‐quadratic control. When the system is subject to sudden and random changes in parameter values, the optimal feedback is computed from the solution of Riccati equations coupled through their weighting terms. After recalling the principle of homotopy methods, it is shown how it generates a new and efficient algorithm for this class of problem. An illustrative example is given.