bluuebunny/crossref_metadata_2025 huggingface dataset:
On a self‐optimizing algebraic approach to symbolic analysis
Authors: Stefański Czeslsaw
Published: July 2007

In this paper a new approach to the symbolic analysis of linear networks is presented. A computer programme based on this approach is briefly described. It is shown that this method in computer applications considerably reduces the number of operations needed, the number of components in the final results and thus the computer time. the method is based on the tableau description of the analysed closed network. Descriptions of elements of the network are optimally chosen successively during the operation of the algorithm. the method presented seems to be the best so far among direct methods of fully symbolic analysis and considerably enhances the possibility of such an analysis.
Design of two‐dimensional scaled state space filters with fixed point arithmetic
Authors: Fahmy M. F. , Abo‐Zahhad M. , El‐Raheem G. A.
Published: July 2007

In this paper a new synthesis method has been proposed for the design of 2D scaled state space filters with fixed point arithmetic. It is based on constructing a non‐singular transformation matrix which minimizes the output noise power and maintains the signal‐scaling condition, besides zeroing some of the entries of the state matrices. As a result, simultaneous savings in both additions and multiplications are achieved. Numerical results are included to illustrate the performance of the proposed structures and to compare them with other structures.
Small‐signal harmonic analysis of non‐linear circuits
Authors: Jokinen Hannu , Valtonen Martti
Published: July 2007

An approximate harmonic analysis method for non‐linear circuits is introduced. the method solves the steady state, time domain representation as well as the frequency response of non‐linear circuits. It allows simulation of non‐ideal switched capacitor circuits composed of any kinds of linear components and non‐linear transistors as switches. All switches must have the same period, but they can be opened and closed at any time. the method proposed may also be applied to mixer analysis for the case of strong LO and weak RF signals. Examples are given to demonstrate that the method is efficient and sufficiently fast to be used in circuit design. the simulation results show good agreement with those obtained by harmonic balance and transient analysis.
Symbolic distortion analysis of non‐linear elements in feedback amplifiers using describing functions
Authors: Floberg Henrik , Mattisson Sven
Published: July 2007

This paper presents a new appoach based on the use of describing functions to obtain approximate symbolic expressions for the fundamental frequency component as well as for the second‐ and third‐order harmonics. A single soft or hard transconductance non‐linearity embedded in an arbitrary linear network is studied. Three examples are considered.
Gluten‐free but also gluten‐enriched (gluten+) diet prevent diabetes in NOD mice; the gluten enigma in type 1 diabetes
Authors: Funda David P. , Kaas Anne , Tlaskalová‐Hogenová Helena , Buschard Karsten
Published: July 2007

Background

Environmental factors such as nutrition or exposure to infections play a substantial role in the pathogenesis of type 1 diabetes (T1D). We have previously shown that gluten‐free, non‐purified diet largely prevented diabetes in non‐obese diabetic (NOD) mice. In this study we tested hypothesis that early introduction of gluten‐enriched (gluten+) diet may increase diabetes incidence in NOD mice.

Methods

Standard, gluten‐free, gluten+ modified Altromin diets and hydrolysed‐casein‐based Pregestimil diet were fed to NOD females and diabetes incidence was followed for 310 days. Insulitis score and numbers of gut mucosal lymphocytes were determined in non‐diabetic animals.

Results

A significantly lower diabetes incidence (p < 0.0001) was observed in NOD mice fed gluten‐free diet (5.9%, n = 34) and Pregestimil diet (10%, n = 30) compared to mice on the standard Altromin diet (60.6%, n = 33). Surprisingly, gluten+ diet also prevented diabetes incidence, even at the level found with the gluten‐free diet (p < 0.0001, 5.9%, n = 34). The minority of mice, which developed diabetes on all the three diabetes‐protective (gluten+, gluten‐free, Pregestimil) diets, did that slightly later compared to those on the standard diet. Lower insulitis score compared to control mice was found in non‐diabetic NOD mice on the gluten‐free, and to a lesser extent also gluten+ and Pregestimil diets. No substantial differences in the number of CD3+, TCR‐γδ+, and IgA+ cells in the small intestine were documented.

Conclusions

Gluten+ diet prevents diabetes in NOD mice at the level found with the non‐purified gluten‐free diet. Possible mechanisms of the enigmatic, dual effect of dietary gluten on the development of T1D are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
The relationship of weight suppression and dietary restraint to binge eating in bulimia nervosa
Authors: Lowe Michael R. , Thomas J. Graham , Safer Debra L. , Butryn Meghan L.
Published: July 2007

Objective:

Recent research has raised important questions about the relationships between weight suppression (WS) (discrepancy between highest‐ever and current weight), dietary restraint, and binge eating in bulimia nervosa (BN).

Method:

In the current study, these variables were studied cross‐sectionally through secondary analyses of baseline data collected in a multi‐site treatment study. Participants (N = 182) were treatment‐seeking women diagnosed with BN. Dietary restraint and binge eating were measured via the Eating Disorders Examination.

Results:

WS was directly and dietary restraint was inversely related to frequency of binge eating. The inverse relationship between dietary restraint and binge eating may be explained in part by the fact that the most restrained patients with BN had the greatest desire to lose weight.

Conclusion:

Implications of these findings for future research on the perpetuation and treatment of BN are discussed. © 2007 by Wiley Periodicals, Inc. Int J Eat Disord 2007
Depression and reliance on ease‐of‐retrieval experiences
Authors: Greifeneder Rainer , Bless Herbert
Published: July 2007

The relationship between level of depressive symptomatology and reliance on the ease‐of‐retrieval heuristic was investigated. In two studies, differences in ease‐of‐retrieval were instigated by means of the paradigm introduced by Schwarz and co‐workers. Subsequently, participants were screened for depressive symptoms with the Allgemeine Depressionsskala (ADS, Experiments 1 and 2) and the Beck Depression Inventory (BDI, Experiment 2). In both experiments, participants were randomly selected from a non‐clinical population. Results indicate that participants with low levels of depressive symptomatology relied on experienced ease or difficulty, whereas individuals with high levels of depressive symptomatology based their judgment on the accessible content information. Theoretical and practical implications of these findings are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Nanocrystalline hydroxyapatite/titania coatings on titanium improves osteoblast adhesion
Authors: Sato Michiko , Aslani Arash , Sambito Marisa A. , Kalkhoran Nader M. , Slamovich Elliott B. , Webster Thomas J.
Published: July 2007

Bulk hydroxyapatite (HA) and titania have been used to improve the osseointegration of orthopedic implants. For this reason, composites of HA and titania have been receiving increased attention in orthopedics as novel coating materials. The objective of this in vitro study was to produce nanophase (i.e., materials with grain size less than 100 nm) HA/titania coatings on titanium. The adhesion of bone forming cells (osteoblasts) on the composite coatings were also assessed and compared with single‐phase nanotitania and nano‐HA titanium coatings. Nanocrystalline HA powders were synthesized through wet chemistry and hydrothermal treatments at 200°C. Nanocrystalline titania powders obtained commercially were mixed with the nanocrystalline HA powders at various weight ratios. The mixed powders were then deposited on titanium utilizing a room‐temperature coating process called IonTite™. The results of the present study showed that such coatings maintained the chemistry and crystallite size of the original HA and titania powders. Moreover, osteoblasts adherent on single‐phase nanotitania coatings were well‐spread whereas they became more round and extended distinct filopodia on the composite and single‐phase HA coatings. Interestingly, the number of osteoblasts adherent on the nanotitania/HA composite coatings at weight ratios of 2/1 and 1/2 were significantly greater compared with single‐phase nanotitania coatings, currently‐used plasma‐sprayed HA coatings, and uncoated titanium. These findings suggest that nanotitania/HA coatings on titanium should be further studied for improved orthopedic applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Expression of the human β3 integrin subunit in mouse smooth muscle cells enhances IGF‐I‐stimulated signaling and proliferation
Authors: Xi Gang , Maile Laura A. , Yoo Sung‐Eun , Clemmons David R.
Published: July 2007

Optimal stimulation of signal transduction and biological functions by IGF‐I in porcine smooth muscle cells (pSMC) requires ligand occupancy of the αVβ3 integrin. Binding of heparin‐binding domain (HBD) of vitronectin (VN) to the cysteine loop (C‐loop) region of β3 is required for pSMC to respond optimally to IGF‐I stimulation. Mouse smooth muscle cells (mSMC), which express a form of β3 whose sequence within the C‐loop region is different than porcine or human β3, do not respond optimally to IGF‐I, and IGF‐I stimulated β3 and SHPS‐1 phosphorylation which are necessary for optimal IGF‐I signaling were undetectable. VN also had no effect on IGF‐I stimulated the cell proliferation. In contrast, when human β3 (hβ3) was introduced into mSMC, there was an enhanced VN binding in spite of an equivalent amount of total β3 expression, and IGF‐I‐dependent β3, and SHPS‐1 phosphorylation were detected. In addition, there was enhanced IGF‐I‐stimulated Shc association with SHPS‐1, Shc tyrosine phosphorylation, Shc and Grb2 association, and MAP kinase activation leading to increased cell proliferation. These enhancements could be further augmented by adding a peptide containing the HBD of VN. To determine if these changes were mediated by the C‐loop region of β3, an antibody that reacts with that region of β3 was utilized. The addition of the hβ3 C‐loop antibody abolished VN‐induced enhancement of IGF‐I signaling and IGF‐I‐stimulated cell proliferation. These results strongly support the conclusion that optimal SMC responsiveness to IGF‐I requires ligand interaction with the C‐loop domain of hβ3. J. Cell. Physiol. 214: 306–315, 2008. © 2007 Wiley‐Liss, Inc.
Surface desorption atmospheric pressure chemical ionization mass spectrometry for direct ambient sample analysis without toxic chemical contamination
Authors: Chen Huanwen , Zheng Jian , Zhang Xie , Luo Mingbiao , Wang Zhichang , Qiao Xiaolin
Published: July 2007

Ambient mass spectrometry, pioneered with desorption electrospray ionization (DESI) technique, is of increasing interest in recent years. In this study, a corona discharge ionization source is adapted for direct surface desorption chemical ionization of compounds on various surfaces at atmospheric pressure. Ambient air, with about 60% relative humidity, is used as a reagent to generate primary ions such as H3O+, which is then directed to impact the sample surface for desorption and ionization. Under experimental conditions, protonated or deprotonated molecules of analytes present on various samples are observed using positive or negative corona discharge. Fast detection of trace amounts of analytes present in pharmaceutical preparations, viz foods, skins and clothes has been demonstrated without any sample pretreatment. Taking the advantage of the gasless setup, powder samples such as amino acids and mixtures of pharmaceutical preparations are rapidly analyzed. Impurities such as sudan dyes in tomato sauce are detected semiquantitatively. Molecular markers (e.g. putrescine) for meat spoilage are successfully identified from an artificially spoiled fish sample. Chemical warfare agent stimulants, explosives and herbicides are directly detected from the skin samples and clothing exposed to these compounds. This provides a detection limit of sub‐pg (S/N ≥ 3) range in MS2. Metabolites and consumed chemicals such as glucose are detected successfully from human skins. Conclusively, surface desorption atmospheric pressure chemical ionization (DAPCI) mass spectrometry, without toxic chemical contamination, detects various compounds in complex matrices, showing promising applications for analyses of human related samples. Copyright © 2007 John Wiley & Sons, Ltd.
Methodical approach for the use of GC‐TOF MS for screening and confirmation of organic pollutants in environmental water
Authors: Portolés Tania , Pitarch Elena , López Francisco J. , Sancho Juan V. , Hernández Félix
Published: July 2007

The potential of gas chromatography coupled to time‐of‐flight mass spectrometry (GC‐TOF MS) for the screening of organic pollutants in water was explored. After a conventional SPE step with C18 cartridges, the comparison of spectra with available libraries together with an evaluation of the mass accuracy was the first approach used for the screening and confirmation of target analytes. However, at low analyte concentrations (i.e. below 0.1 µg/l), this procedure was not feasible and the use of the application manager TargetLynx was evaluated. This application allows the selection of up to five representative ions per analyte, measured with high mass accuracy, and their intensity ratio evaluation. Ion selection, extraction mass window and concentration levels were found to be the critical parameters. The reference compound used as ‘lock mass’ was also found to affect to the quality of information obtained in some particular cases.

Full spectral acquisition data generated by the TOF MS analyzer allowed investigation of the presence of several analytes in samples in a post‐target style, without the need of reanalyze the water samples.

Finally, a methodical approach was established for the reliable screening and confirmation of organic pollutants (PAHs, pesticides, octyl/nonyl phenols) in real‐world samples, which led to satisfactory results of ∼0.1 µg/l. Copyright © 2007 John Wiley & Sons, Ltd.
Temporal electronic structures of nonresonant Raman excited virtual states: a case study of ethylene thiourea
Authors: Fang Chao , Wu Guozhen
Published: July 2007

An algorithm is employed to elucidate molecular bond polarizabilities of ethylene thiourea including their temporal relaxation from Raman intensities, which provide much information concerning the electronic distribution of nonresonant Raman excited virtual states. The main character of the excited states of ethylene thiourea is that the excited electrons tend to flow to the molecular periphery because of electronic repulsion. It is noted that the bond electronic densities of the ground state can be mapped out by the bond polarizabilities at the final stage of relaxation. The relaxation time is shown to be proportional to the wavelength of the exciting light in agreement with Heisenberg's uncertainty principle, showing that the excitations are indeed not the stationary eigenstates. Copyright © 2007 John Wiley & Sons, Ltd.
Should U. S. use occupancy tax?
Authors: Heer Clarence
Published: July 2007

Authorities cite pros and cons, discuss problems involved in a change in the basis of assessing real estate from a capital to a rental basis ae used in England and Wales.
Milwaukee goes debt free
Authors: Gladfelter Lloyd
Published: July 2007

City's fifty‐year program, actually achieved in 21 years, sets sound example for suburban neighbors and bolsters morale of city officials for problems of postwar period.
Let's look at civil service!
Authors: Kaplan H. Eliot
Published: July 2007

Merit aystem champion calls for end of archaic methods, red tape of meaningless precedent and tradition; sees modernization of personnel practices a postwar need.
Rural county can be efficient
Authors: Renne R. R.
Published: July 2007

Manager plan, tried for first time in sparsely populated area, cuts government costs to fit shrunken tax revenues after oil resources run out in Petroleurn County, Montana.
Philadelphia tax in fifth year
Authors: Patterson Robert J.
Published: July 2007

Earned income tax produces one‐fourth of city's revenues, balances budget after two decades of deficits, forestalls increase of property tax or renewal of unpopular sales tax.
By their own bootstraps, II
Authors: Tugman William M.
Published: July 2007

Eugene and Lane County descend together into the depths of debt over the typical free‐spending road; problem: how to persuade the people to break a century‐old habit.
They want to be good citizens
Authors: Gallup George H.
Published: July 2007

Public opinion expert holds that political chicanery, apathy and failure of schools thwart eflective citizenship.
The world demands proof
Authors: Miller Spencer
Published: July 2007

Democracy must not be lost in the community and state if we are to succeed in preserving it in the nation and world.
Too small to be efficient?
Authors: Renne R. R.
Published: July 2007

Experience of Petroleum County, Montana, cited as proof council‐manager plan will cut costs, improve operations.
How to get a new constitution
Authors: Chute Charlton F.
Published: July 2007

It takes a lot of doing and the vital need is to inform the people thoroughly on what is wrong with the old one.
Simplifying state's business
Authors: Bromage Arthur W.
Published: July 2007

Revitalizing of administrative processes with citizen leadership seen best way to resist federal centralization.
What is there to coordinate?
Authors: Payne Clifford F.
Published: July 2007

The people of Henry County, Indiana, demonstrate healthy reluctance to stay with tradition when it ceases to work.
New British towns for old
Authors: Osborn F. J.
Published: July 2007

Nationwide program is designed to curb growth of large cities and to develop new communities of 30,000 – 60,000.
The state of the states—1947
Authors: Peak George W.
Published: July 2007

Governors show tendency to pitch messages on high plane, wrestle sincerely with multiplicity of urgent problems.
Let's talk things over right
Authors: Witman Shepherd L.
Published: July 2007

Well organized discussion programs properly carried on will bring understanding and sound democratic action.
City‐county merger proposed
Authors: Martin Roscoe C.
Published: July 2007

Citizen legislative advisory commission uses effective plan to study Birmingham and Jefferson County problems.
Watchdogs of local finance
Authors: Sly John F. , Alderfer H. F. , Brannon Victor D.
Published: July 2007

New Jersey, Pennsylvania and Missouri exercise varying degrees of supervision over city and county treasuries.
Working together on airports
Authors: Harold De Nike J.
Published: July 2007

Cooperation of all levels of government, not special [righte], needed to help solve aviation problems.
Always fun in new orleans
Authors: Holloway W. V.
Published: July 2007

Both political machines and reformers try to dodge merit system, but its use has brought measurable progress.
Cambridge does it again!
Authors: O'Connor John
Published: July 2007

Manager plan brings efficient government, debt reduction, salary increases, while lowering tax rate for sixth year.
Centralization vs. home rule
Authors: Wager Paul W. , Walker Harvey
Published: July 2007

Ohio cities' plea for taxing power contrasts with North Carolina's experience with absorption of local functions.
Should lawyers be citizens?
Authors: Seasongood Murray
Published: July 2007

Former Cincinnati mayor challenges attorneys to civic action and urges them to “get into politics” while young.
20th century public service
Authors: Chatters Carl H.
Published: July 2007

Number of government activities continues to grow with much overlapping or division of functionr between three levels.
Did we modernize congress?
Authors: Kefauver Estes
Published: July 2007

Representative Kefauver analyses progress made by 1946 act and demands public support of job still to be done.
The atom in local democracy
Authors: Edison Charles
Published: July 2007

League's President warns that people must guard against use of new power as excuse for greater centralization.
City manager for washington?
Authors: Auchincloss James C.
Published: July 2007

Congressional committee finds government of capital city a hopeless hodge‐podge; suggests council‐manager plan.
Toward firmer foundation
Authors: Moore Frank C.
Published: July 2007

Local governments need [full measure of power essential to successful performance] of their jobs, says finance.
Pattern for Greater Boston
Authors: Cherington Charles R.
Published: July 2007

Majority of people in its 83 communities refuse to face economic and functional facts, educator at Harvard warns.
Local government's story
Authors: Nadig Henry Davis , Carlson Eric
Published: July 2007

Conscious public retations policy urged to overcome public apathy and ignorance on municipal problems.
You must know your town
Authors: Judd Dorothy L.
Published: July 2007

Dynamic promotion of democracy through booklets on each community helps to produce politically mature citizens.
Westchester likes executive
Authors: Robertson Hugh W.
Published: July 2007

Ten years with elected administrator brings effciency but no lessening of political control to [richest] county.
Des Moines drops own plan
Authors: Stroud Katherine R.
Published: July 2007

City which set style in cornmission government in 1908 finally wins council‐manager form after bitter campaign.
Spending for a better flint
Authors: Page G. Keyes
Published: July 2007

Costly improvement program to make up jor [drought] of depression and war years guided by taxpcryers' group.
Better look before you fly
Authors: Prokosch Walther
Published: July 2007

Communities rhould make careful survey of airport needs and not [plan by intuition], says aeronautical consultant.
We must keep ballot short
Authors: Childs Richard S.
Published: July 2007

Survey shows that ticket makers step in to [help] in cities where voter must vote for nine for city council.
Cleaning up the restaurants
Authors: Trout Maurice E.
Published: July 2007

Health authorities educate the public and proprietors to need for strong regulation with workable review board.
Housewives jolt politicians
Authors: Ek Carl
Published: July 2007

Six women amateurs who forced foes to desperate tactics in Passaic, N. J., struggle, vow “fight has just begun”.
Hartford likes its new plan
Authors: Gravlin Leslie M.
Published: July 2007

Manager government, year and a half old, brings reduction in taxes as well as increased efficiency of operation.
The new German charter
Authors: Jones Howard P.
Published: July 2007

“Basic rights which are the keystones of the democratic arch are strongly guaranteed” by the document adopted.
Mayor Charlie Cuts corners
Authors: Kent George
Published: July 2007

Louisville's chief executive drops red tape to get things done; hires city administrator; acts on citizen [beefs].
Can we afford the initiative?
Authors: Smith Alfred F.
Published: July 2007

California's experience indicates need to revamp law to insure sound measures and solvency of state's finances.
Old father penn's weakling
Authors: Kaplan H. Eliot
Published: July 2007

War and unsympathetic oficials aid in undermining civil service provisions for some Keyatone State departments.
Choosing judges in Missouri
Authors: Hyde Laurance M.
Published: July 2007

State's plan makes podsible selection of judiciary on merit alone, with tenure based on satisfactory service.
Better schooling, less cost
Authors: Benton E. Maxwell
Published: July 2007

Arkansas on way to achieving greater eficiency as well ad higher standards when voters cut districts two thirds.
Labor's stake in civic affairs
Authors: Kroll Jack
Published: July 2007

Political Action Committee director tells why unions fight to make communities better places for a good life.
Distributed parameter systems approach to the optimal cattle ranching problem
Authors: Derzko N. , Sethi S. P. , Thompson G. L.
Published: July 2007

This paper describes a maximum principle for distributed parameter systems, i.e. systems characterized by partial differential equations. The maximum principle is applied to solve the problem of a cattle rancher who must decide the number of cattle in different age groups to be bought and sold at each instant in order to maximize his profits.
Control design for magnetic suspension
Authors: Vincent Thomas L.
Published: July 2007

Through proper design, it is possible to build an electromagnetic bearing system, using a ferromagnetic rotor, such that there exists an equilibrium position in the magnetostatic field which is unstable only in the axial direction. In order to achieve axial stability, a regulator may be employed to vary the current in the coils whenever the rotor is displaced from the equilibrium position. The idea is to vary the current in such a way that the resultant change in the magnetic, field produces a restoring force to the rotor.

This study is devoted to an investigation of the relative merits of various control laws which could be implemented by the regulator. The rotor is to be maintained in the vicinity of the equilibrium point even if an external force is present which enters the system as an unknown but bounded function of the system state and time.

Recent magnetic suspension systems have been designed using a regulator based on linear state variable feedback. It is shown here that asymptotic stability cannot be maintained for the system in the presence of an external force if linear feedback control is used. The effect of an unknown but bounded external force on the system is vividly demonstrated by using qualitative methods to find the boundary of the set reachable under this force. Linear state variable feedback can maintain partial controllability of the system to some neighbourhood of the equilibrium point provided a simple inequality relationship between the feedback parameters and the bounds on the external force is maintained. Finally, it is shown that a game theoretic approach may be used for a nonlinear regulator design which will result in an asymptotically stable system in the presence of an unknown but bounded external force.
Sequential conjugate gradient‐restoration algorithm for optimal control problems with non‐differential constraints and general boundary conditions, part 2
Authors: Wu A. K. , Miele A.
Published: July 2007

In Reference 1, Wu and Miele developed the sequential conjugate gradient‐restoration algorithm for minimizing a functional subject to differential constraints, with or without non‐differential constraints, and general boundary conditions. In this paper, several numerical examples are presented. Some of these pertain to a quadratic functional subject to linear constraints, and some pertain to a non‐quadratic functional subject to non‐linear constraints. These examples demonstrate the feasibility as well as the convergence characteristics of the sequential conjugate gradient‐restoration algorithm.
Two methods for the solution of the dynamic programming algorithm on a multiprocessor cluster
Authors: Al‐Dabass D.
Published: July 2007

The dynamic programming algorithm is examined with a view to solving it on a multiprocessor cluster. The two methods of control‐space division and state‐space division are proposed, and their efficiency is analysed in detail. A practical example is given to illustrate the two methods using a two‐processor system, and the results are projected to find the minimum achievable time and optimum number of processors for this example.
Optimal active‐reactive hydro‐thermal schedules using functional analysis
Authors: El‐Hawary M. E. , Christensen G. S.
Published: July 2007

A new approach to the hydro‐thermal optimal active and reactive power scheduling problem is proposed. The optimal schedules for a system with thermal and common‐flow hydro‐plants are obtained. The active‐reactive power balance model of the electric network is introduced. Although not as accurate as the load‐flow model, the present model is simpler. The scheduling problem is solved by use of the minimum norm formulation of functional analytic optimization.
Guaranteed cost solution of optimal control and game problems for uncertain systems
Authors: Mahalanabis A. K. , Rana R.
Published: July 2007

A class of systems having white noise parameter variations is considered. Solutions of the infinite‐time quadratic optimal control (LQOC) and differential game (LQDC) problems are considered. It is shown that guaranteed cost solutions of these problems are possible if the effects of parameter uncertainties are first taken into account in a specified manner. The method is illustrated through a numerical example.
The effects of mismatch on an optimal control scheme for linear systems with control time delays
Authors: Hocken R. D. , Marshall J. E.
Published: July 2007

An essential feature common to control schemes for plants with time delays is the use of a plant model for purposes of prediction. Any difference between plant and model is referred to as mismatch. The paper is concerned with how mismatch affects the stability and performance of an optimal control scheme for linear systems with delay in control.
High‐order necessary optimality conditions for control problems with terminal constraints
Authors: Gorokhovik V. V.
Published: July 2007

This is a survey of high‐order necessary optimality conditions for control problems with inequality and equality terminal constraints. Both classical and Pontryagin extremals are considered. For classical extremals, the characteristics of necessary optimality conditions in terms of variations are given, and the investigations devoted to Kelley's conditions are discussed in detail. For Pontryagin extremals, two types of results are given: generalizations and extensions of matrix impulse optimality condition and high‐order maximum principle.
Numerical solution of the symmetric riccati equation through riccati iteration
Authors: Anderson Leonard R. , Brewer Dennis W. , Baykan A. Rasim
Published: July 2007

This paper presents a new method for solving the symmetric algebraic Riccati equation from optimal control. The new method employs ‘Riccati iteration’ as used for time‐scale decoupling in structural vibration problems. The rate of convergence of the algorithm is governed by the relative separation of small and large eigenvalues in the shifted Hamiltonian equations. If this ratio of eigenvalues is less than one, the algorithm is globally convergent. Riccati iteration is demonstrated for a set of 8th‐order linear‐quadratic regulator problems, and preliminary timing and accuracy comparisons are presented.
Solution algorithms for non‐linear singularly perturbed optimal control problems
Authors: Ardema Mark D.
Published: July 2007

The applicability and usefulness of several classical and other methods for solving the two‐point boundaryvalue problem which arises in non‐linear singularly perturbed optimal control are assessed. Specific algorithms of the Picard, Newton and averaging types are formally developed for this class of problem. The computational requirements associated with each algorithm are analysed and compared with the computational requirement of the method of matched asymptotic expansions. Approximate solutions to a linear and a non‐linear problem are obtained by each method and compared.
Optimal pulse motor control
Authors: Calise Anthony J. , Smith Stan
Published: July 2007

This paper considers the problem of optimal multiple‐pulse motor control. Simple pulse‐triggering algorithms are derived that are suitable for real‐time implementation in air‐launched tactical missiles. Two motor designs are addressed. The first is typical of solid radial pulse motor designs, where the number of pulses and the total impulse of each pulse is defined. The second corresponds to a liquid multipulse motor, where the thrust magnitude and total motor impulse are defined and the pulse initiation and pulse termination times are variable. Sensitivity of performance to pulse initiation time and pulse shape is discussed, and simulation results are included to demonstrate the effectiveness of the pulse‐triggering algorithms.
Optimal structural design and relaxed controls
Authors: Lurie K. A. , Cherkaev A. V.
Published: July 2007

Problems of optimal design, particularly of the optimal distribution of various materials within the volume of a structure, require consideration of all possible mixtures, i.e. composites, which can be assembled from given components. This paper explains both the mathematical and the physical reasons for such an extended formulation, and it summarizes results which have been obtained concerning effective transport coefficients. Specifically, we describe the set G, U of effective conductivity tensors of composites which may be assembled from components in a given set U taken in prescribed proportions m. By using G, U instead of U as the set of admissible controls, one guarantees the existence of an optimal control for a large class of weakly lower‐semicontinuous functionals of solutions of various boundary‐value problems.
An integrated approach to reduced‐order control theory
Authors: Kabamba P. T. , Longman R. W.
Published: July 2007

Linear‐Quadratic‐Gaussian (LQG) theory generally requires the use of a full‐order dynamic observer whose dimension is often prohibitive in applications so that reduced‐order controller design techniques are needed. A general formalism is presented here for the optimal design of controllers of arbitrary prescribed order with the usual quadratic cost functionals. The gradients of the cost functional are obtained in explicit form and involves Liapunov equations. A fundamental aspect of this paper is a unifying formalism; direct output feedback and reduced‐order controllers, stochastic and deterministic systems, infinite‐time and finite‐time problems and time‐invariant and time‐varying problems are considered. Optimization of sensor and actuator locations and parameter‐variation‐insensitive controller design are also considered within this framework. Examples are treated.
Optimal preventive and repair maintenance of a machine subject to failure
Authors: Gaimon Cheryl , Thompson Gerald L.
Published: July 2007

Machine maintenance policies comprise two important activities: (a) the performance of preventive maintenance to prevent or postpone future breakdowns; and (b) the decision once a breakdown has actually occurred either to repair or to junk the machine. In this paper we study a control‐theoretic model in which both of these activities are decision variables. The optimal preventive maintenance policy is determined as an ordinary control variable, whereas the breakdown‐repair policy is determined as an impulsive control variable. A real‐time iterative procedure is presented for making the repair‐or‐junk decision at the time of each actual breakdown. Various theoretical results are presented which connect the preventive and breakdown‐repair policies.
Quantized control using differential encoding
Authors: Fischer Thomas R. , Tinnin D. Joy
Published: July 2007

A vector generalization of differential pulse code modulation is used to provide quantization of control and measurements in a closed‐loop control system. Algorithms are developed for the adaptive quantizer and predictor. Explicit expressions are derived for the quantization and estimation errors resulting from the differential encoding. Simulation results are presented which demonstrate that even for very low bit rates the quantized control performance is very close to the performance of the unquantized optimal control solution.
A newton‐type computing technique for optimal control problems
Authors: Pillo G. Di , Grippo L. , Lampariello F.
Published: July 2007

In this paper we propose some Newton‐type algorithms for the numerical solution of both unconstrained and constrained discrete‐time optimal control problems. The approach followed here is based on a suitable augmented Lagrangian function whose unconstrained minimization yields the solution of the optimal control problem and the associated multipliers. We show that the Hessian matrix of the augmented Lagrangian function has a sparse structure which allows the use of an efficient decomposition scheme for the computation of the Newton's direction. In addition, consistent approximations of the Newton's direction are described. These approximations may allow a further reduction of the computational cost. Two numerical examples are reported.
Optimal control of inspiratory airflow in breathing
Authors: Hämäläinen Raimo P. , Sipilä Aarne
Published: July 2007

This paper describes a new optimal control model for predicting the inspiratory airflow pattern in breathing. The dynamics of the mechanical lung‐rib‐cage system is described by a linear first‐order equation. The physiological interpretation of the mathematical optimization criterion used in the model is the minimization of oxygen expenditure of the respiratory muscles together with the avoidance of movements with rapid changes in the flow rate. The optimal control analysis results in a relatively difficult two‐point boundary value problem which is solved by multiple shooting techniques. The new criterion yields better predictions for breathing at rest than previous models. The most significant improvements are that this model is able to produce asymmetric inspiratory airflow patterns and to predict the effects of changes in the operating level and the elastance coefficient of the system. A modified version of the model is suggested which would be able to predict patterns of breathing during exercise as well.
Optimal design problems for curvilinear shallow elements of structures
Authors: Banichuk N. V. , Larichev A. D.
Published: July 2007

New problem statements for the optimal design of thin‐wall structural elements are considered by means of optimal control theory. The distribution of initial curvature of shallow curvilinear structural elements in a non‐strain state is taken as the control function.1–3 Integral stiffness is considered as the optimized performance index. The necessary optimality condition and the partial differential equations for the adjoint variables are derived. An analysis of these relations is carried out, and the initial optimal control problem is reduced to a boundary problem of the bending of an uncurved element. Problems of optimal design of plates under transverse loads, as well as under tensile or compression forces acting in the middle surface, are studied. Analogous problems of optimal design for shallow curvilinear plates on an elastic foundation are also investigated. Some two‐dimensional analytical solutions for optimal plates under loads of different types are obtained.
Strong decision and forecast horizons in a convex production planning problem
Authors: Teng Jinn‐Tsair , Thompson Gerald L. , Sethi Suresh P.
Published: July 2007

We consider a production‐inventory planning problem with time‐varying demands, convex production costs and a warehouse capacity constraint. It is solved by use of the Lagrangian form of the maximum principle. The possible existence of strong decision and forecast horizons is demonstrated. When they exist, they permit the breaking up of the whole problem into a set of smaller problems which can be solved independently because optimal decisions up to a strong decision horizon are completely independent of demand data beyond the next forecast horizon. A forward branch and bound algorithm is developed to determine such horizons and to solve the whole problem.
Advertising decisions in oligopoly: An industry equilibrium analysis
Authors: Rao Ram C.
Published: July 2007

This paper determines the stationary level of advertising in which firms in an oligopoly invest. These levels are outcomes of an industry equilibrium which corresponds to a Nash solution to the set of maximizing problems that firms face. The existence of an equilibrium is established for two alternative specifications of the dynamics of advertising. Stability, and therefore observability, of stationary states is examined.
Feasibility of disturbance‐accommodating control in steering of a large tanker
Authors: Mears Barry C. , Reid Robert E.
Published: July 2007

The feasibility of applying disturbance‐accommodating control (DAC) techniques to the problem of steering control of a large tanker in a seaway is examined. A performance criterion representative of propulsion losses related to steering is used as a basis for the design of course‐keeping controllers. The development of disturbance state models to take advantage of the short‐term regularity of the seaway within a DAC framework is presented. Comparisons are made between the performance resulting from the DAC approach and previous LQG approaches to the problem using computer simulation results. On this basis, it is shown that controller design within a DAC framework may be a viable alternative to existing Kalman filter estimation/control schemes used in autopilot design.
Some experiences with the application of multivariable adaptive control in chemical and electromechanical plants
Authors: Hahn V. , Röck H. , Schmid Chr. , Wiemer P.
Published: July 2007

Based on a new unified theory, multivariable adaptive generalized minimum variance and model reference adaptive control are applied to three different types of processes. The improvement of control quality in a foil coating process using adaptive control is significant. Reduced energy costs can be really achieved on distillation columns as shown on a production column. The tuning of a multivariable controller for a turbogenerator can be done automatically and yields satisfactory disturbance rejection. The examples illustrate that adaptive control using these techniques has reached a high degree of maturity, making it a powerful tool for the control engineer.
Implicit dual control for general stochastic systems
Authors: Bayard David S. , Eslami Mansour
Published: July 2007

A new implicit dual technique is presented for stochastic adaptive control synthesis. In this technique, denoted as the method of utility costs (MOUC), a new control policy is derived from a known starting control policy by using a single iteration in time‐varying policy space. An important result is that the new control policy yields a corresponding improvement in adaptive performance relative to the known starting policy. Since the starting policy can be chosen arbitrarily, the new policy has potentially superior performance relative to any existing design. Unlike other implicit dual designs, the MOUC can be applied to systems having constrained inputs, discontinuities, discrete valued disturbances, as well as in situations where the variances of the associated process statistics are large. A numerical example is given in which a controller is synthesized to provide improved performance relative to the Open‐Loop Feedback policy of Dreyfus.
Equilibria and threats in a fishery management game
Authors: Hämäläinen R. P. , Haurie A. , Kaitala V.
Published: July 2007

A two‐country fishery management game is considered in the realm of the theory of non‐co‐operative and co‐operative differential games. Conditions which guarantee global asymptotic stability of the open‐loop equilibrium trajectories are given and applied to a class of harvest games. Co‐operative solutions of the two‐country fishery management games are examined for the case of Kalaï‐Smorodinsky bargaining schemes. We show that the use of retaliation threats can transform a co‐operative solution into an equilibrium memory strategy. Two numerical examples present an analysis of threat effectiveness. The ‘turnpike’ property, or global asymptotic stability of optimally controlled systems, is an important part of the computational approach used.
Optimal proportional plus integral control for regulator and tracking problems
Authors: Wong Kin P. , Seborg Dale E.
Published: July 2007

Two new design methods are proposed for optimal PI control which give fast recovery from load disturbances without producing large overshoots associated with set‐point changes. Unlike existing methods, such as set‐point filtering or any other scheme that essentially detunes the controller for set‐point changes, the proposed methods do not increase the rise time significantly in order to reduce overshoot. The first method resets the integral term in the control law when the new set point is reached. The second method is a modified model‐following approach that does not increase the overall dimension of the system. Two numerical examples demonstrate that the proposed methods are superior to alternatives such as set‐point filtering and conventional model following.
Singular perturbation modelling and design techniques applied to jet engine control
Authors: Syrcos George P. , Sannuti P.
Published: July 2007

This, paper presents an application of recent singular perturbation modelling techniques for design and control of the F‐100 jet engine. The required feedback gains are calculated using a Chandrasekhar type of algorithm.
Optimal parametrized design of thermal diffusers for communication satellites
Authors: Delfour M. C. , Payre G. , Zolesio J.‐P.
Published: July 2007

The object of this paper is to present recent developments in the design of mass‐optimized thermal diffusers with a priori specifications on the input power flux and a bound on the output power flux. This problem arises in connection with the use of high power solid state devices (HPSSD's) in future Canadian communication satellites. Delfour, Payre and Zolésio1,2 have obtained results on the optimal design using the techniques of shape optimal design.3‐8 In this paper, we also consider suboptimal designs (e.g. doublers) and compare them with the optimal one. A similar problem has been studied by Destuynder.9 However, the present design differs in that we have a constraint on the normal derivative on a piece of the boundary surface instead of a constraint on the maximum temperature in the domain or body of the diffuser.
Optimal feedback control of power systems governed by non‐linear dynamics
Authors: Biswas S. K. , Ahmed N. U.
Published: July 2007

Linear‐quadratic regulator theory is commonly used in feedback optimization problems for power system stabilization. In this paper an extension of Gamkrelidze's maximum principle, which applies directly to non‐linear systems, is used to find an optimal feedback control law from a given practically implementable class of parametrized control structures. An algorithm for finding the optimal set of parameters is presented. The results obtained, using the optimal feedback control law determined by the given algorithm, indicate a substantial improvement of the transient performance of the system.
A primal‐dual method for linear‐quadratic gaussian control problems with quadratic constraints
Authors: Toivonen H. T.
Published: July 2007

Linear‐quadratic Gaussian control with quadratic state and input constraints is studied. A primal‐dual method is considered in which the solution of a dual maximization problem is found by solving a sequence of unconstrained linear‐quadratic Gaussian control problems. Second derivatives are derived for the dual problem and Newton‐type methods are applied to its solution. Non‐negativity constraints on the Lagrange multipliers of the primal problem lead to corresponding constraints in the dual problem, and for these both an active set strategy and a method based on quadratic subproblems are considered. A numerical example is presented to illustrate the performance of the numerical algorithms.