bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isothiocyanate sulforaphane inhibits protooncogenic ornithine decarboxylase activity in colorectal cancer cellsviainduction of the TGF‐β/Smad signaling pathway
Authors: Kaminski Bettina M. , Loitsch Stefan M. , Ochs Meike J. , Reuter Kerstin C. , Steinhilber Dieter , Stein Jürgen , Ulrich Sandra 
Published: July 2010

AbstractScope:The objective of this study was to elucidate molecular mechanisms behind the antitumor activities of the isothiocyanate sulforaphane (SFN) in colorectal cancer cells.Methods and results:Cell growth was determined by BrdU incorporation and crystal violet staining. Protein levels were examined by Western blot analysis. Ornithine decarboxylase (ODC) activity was assayed radiometrically. Reverse transcriptase‐PCR was used for measuring mRNA expression. For reporter gene assays plasmids were transfected into cells via lipofection and luciferase activity was measured luminometrically. Acetyl‐histone H3 and H4 chromatin immunoprecipitation (ChIP) assays were performed followed by PCR with TGF‐β‐receptor II promoter specific primers. We could show that SFN‐mediated cell growth inhibition closely correlates with a dose‐dependent reduction of protein expression and enzymatic activity of ODC. This effect seems to be due to reduced protein levels and transactivation activity of transcription factor c‐myc, a direct regulator of ODC expression, as a consequence of SFN‐induced TGF‐β/Smad signaling. The coherency of these results was further confirmed by using TGF‐β receptor kinase inhibitor SB431542, which largely abolishes inhibitory effects of SFN on both, ODC activity and cell growth.Conclusion:Since elevated ODC enzyme activity is associated with enhanced tumor development, SFN may be a dietary phytochemical with potential to prevent carcinogenesis.
Wenn ein Chemiestudium nicht das Richtige ist
Authors: van Ahn Jessica 
Published: July 2010

AbstractEin Drittel aller Chemiestudenten brechen ihr Studium ab und kehren der Universität endgültig den Rücken. Abbrecher, die zwar vom Chemiestudium überfordert sind, aber Spaß am Fach haben, können zwischen verschiedenen Berufsausbildungen wählen. Beratung bieten Universitäten und die Agentur für Arbeit an.
Akademia‐Industrie‐Austausch:ein Schuss Neugier und Offenheit
Authors: Schneider Jörg J. 
Published: July 2010

AbstractDie jüngst gestartete AIA‐Initiative der GDCh und des Fonds der Chemischen Industrie soll Akademia und Industrie wieder enger miteinander verzahnen. Im Rahmen dessen hat Jörg Schneider von der TU Darmstadt im Konzeptlabor von Merck geforscht. Er berichtet über seine Erfahrungen.
Sauber ins GC/MS
Authors: Lerch Oliver 
Published: July 2010

AbstractUm Pestizidrückstände in Obst und Gemüse zu analysieren, ist eine Extraktion mit anschließender GC/MS‐Analyse die Methode der Wahl. Die Rohextrakte enthalten aber meist noch schwer verdampfbare Bestandteile. Die Lösung des Problems: ein zwischengeschalteter automatisierter Reinigungsschritt.
Ein tiefer Blick ins Glas
Authors: Wizenmann Tobias 
Published: July 2010

AbstractIst der Dornfelder zu sauer? Enthält der Merlot zu viel Zucker? Bei der Qualitätskontrolle von Wein hilft die FT‐IR‐Spektroskopie: Sie bestimmt viele Parameter in einer Messung.
55 000 Ölproben im Jahr titrieren
Authors: Muhr Hans‐Joachim 
Published: July 2010

AbstractWägen ist genauer als Pipettieren — aber Wägen braucht mehr Zeit und ist schwer zu automatisieren. Was tun bei vielen Tausend viskosen Ölproben im Jahr? Ein System von Mettler‐Toledo pipettiert und titriert die Proben automatisch.
Three‐phase medium model for filled rock joint and interaction with stress waves
Authors: Ma G. W. , Li J. C. , Zhao J. 
Published: July 2010

AbstractA three‐phase medium model is proposed in describing the dynamic property of filled rock joints and an analytical study on longitudinal wave transmission normally across a three‐phase rock joint is presented. Parameters in the three‐phase medium model were determined by a series of modified split Hopkinson pressure bar (SHPB) tests, where a sand or clay layer was used to represent an artificially filled rock joint. The effect of the unloading path on the transmitted wave was discussed by comparing the analytical and SHPB test results. The derived wave transmission coefficients across the filled joint agreed very well with those from the test results. Both the analytical and the test results showed that the wave transmission coefficients were affected by the mechanical properties of the fillings. Parametric studies with respect to the volume ratios of water and air in the three‐phase medium and the type of filling material have also been performed. Copyright © 2010 John Wiley & Sons, Ltd.
Dental chipping: Contrasting patterns of microtrauma in inuit and European populations
Authors: Scott G. Richard , Winn J. R. 
Published: July 2010

AbstractWhile the study of dental wear has enjoyed wide popularity for over 100 years, dental chipping, or microfractures of the tooth crown, has received little attention. Observations on dental chipping in populations from the Arctic (St. Lawrence Island, Alaska) and Europe (medieval Norway and Spain) reveal patterns of microtrauma that provide insights into the dietary and tooth‐tool use behaviour of earlier populations. St. Lawrence Island Inuit, with an emphasis on consuming tough and frozen foods, in combination with extensive tooth‐tool use, exhibit a pattern of chipping that is characterised as ‘molar dominant’. The two European samples exhibit an ‘incisor‐dominant’ pattern but contrast markedly in frequencies, with medieval Norwegians showing significantly more chipping than medieval and post‐medieval Spanish. The systematic study of chipping promises to provide a new perspective on how populations used and/or abused their dentitions in earlier times. Copyright © 2010 John Wiley & Sons, Ltd.
Stochastic control of a pension fund model with first‐order Markov‐dependent parameters
Authors: Parlar Mahmut 
Published: July 2010

AbstractThe well known problem of the optimal control of a stochastic discrete linear system with independent parameters and with a quadratic objective functional is generalized to the case where the parameters of the system constitute a first‐order Markov chain. The solution to this more general problem is obtained by the principles of stochastic dynamic programming, and the ‘bi‐feedback’ nature of the optimal controls is explained. The results are applied to the solution of a 25‐period stochastic pension funding problem where it is assumed that the market returns constitute a first‐order Markov chain.
Application of improved optimal regulator technique to power electronics
Authors: Tsuchiya Takeshi , Osiadacz A. , Bell D. J. 
Published: July 2010

AbstractA control system synthesis method for a multi‐input and multi‐output system with input dead time, input variable constraints, and state variable inequality constraints is described. A practical control algorithm which is suitable for microprocessor implementation is derived from the method and is applied to an induction motor control problem. Good simulation results are obtained, although the designed control system is suboptimal. The control system configuration designed by this method is explained clearly. It is proved that integral actions as well as proportional actions are introduced so as to guarantee good steady‐state characteristics in spite of parameter variations of the controlled object. Moreover, a kind of derivative action is introduced to compensate for input dead time effects.
State parameterization approach to the solution of optimal control problems
Authors: Sirisena H. R. , Chou F. S. 
Published: July 2010

AbstractA direct method for solving optimal control problems by parameterizing state variables is developed. This state parameterization (SP) procedure is first formulated for a general class of problem. Next, a simpler and more efficient alternative version of the SP algorithm is developed for an important special class of problems, namely those involving systems that can be cast into a multivariable non‐linear phase‐variable form. The modified SP algorithm in particular avoids explicit integration of the system state and costate differential equations. The algorithm is tested on two problems which are parameterized in terms of cubic splines.
Long‐term optimization of hydro‐thermal power systems by generalized Conjugate‐Gradient Methods
Authors: Sirisena H. R. , Halliburton T. S. 
Published: July 2010

AbstractThe optimal management of hydro storage reservoirs is considered. The objective is to minimize thermal power station fuel costs, over a horizon of one or more years, in a mixed hydro‐thermal power system. A model of the New Zealand system is developed that is simple enough for computational purposes but nevertheless accounts for all major factors including load diversity and transmission losses. A version of Powell's generalized conjugate‐gradient algorithm with Beale restarts is used for the optimization. State and control constraints are enforced by penalty functions and transformations, respectively. Results are presented for a reduced‐order model of the New Zealand system.
Method of successive approximations for solution of optimal control problems
Authors: Chernousko F. L. , Lyubushin A. A. 
Published: July 2010

AbstractThe paper contains a survey of results devoted to one of the numerical methods of optimal control—the method of successive approximations. This method is based on Pontryagin's maximum principle and is known in the English literature as the min‐H method. Various modifications of the method and some theoretical results on its convergence are presented. Examples of applications of the method for the calculation of optimal trajectories are given. The method of small parameters which is close to the method of successive approximations, is also described.
Optimal control of store‐and‐forward networks
Authors: Filipiak Janusz 
Published: July 2010

AbstractThis paper describes a general point of view on the subject of store‐and‐forward queueing networks. A systematic approach to a store‐and‐forward network as a whole is applied. This allows network problems which involve dynamic optimization of congestion control and routing to be treated in a common framework. The dynamic model applied is non‐linear and can be handled straightforwardly by optimal control system theory. It is shown that under normal operational conditions the optimal flow pattern is given by the steady‐state solution of the costate equations. Properties of the optimal flow pattern are examined in detail. Then, schemes of the operation of the network under different operating conditions are discussed at length. It is shown that the optimal control strategies depend on the total volume of traffic forwarded to the network. Algorithms are developed for different traffic demand patterns, and a numerical example is also given.
Ellipsoidal bounds for sets of attainability and uncertainty in control problems
Authors: Chernousko F. L. 
Published: July 2010

AbstractThe guaranteed approach to a description of uncertainties in control problems is developed and is based on an approximation of sets to which uncertain vectors belong by means of optimal ellipsoids. Optimal and suboptimal algebraic operations with ellipsoids (sum, intersection) are presented. By means of these operations, differential equations are obtained which describe the evolution of ellipsoids which provide external and internal bounds on the attainable sets for linear controlled systems. The developed theory is generalized for non‐linear systems and is applied to obtain bounds in optimal control problems and differential games and to obtain minimax filtering in systems with incomplete information. Some examples are also given.
Stability and optimal exploitation over an infinite time horizon of interacting populations
Authors: Haurie A. 
Published: July 2010

AbstractModels of optimal control of two‐species ecological systems are considered on an infinite time horizon. Conditions are obtained under which the optimal exploitation of the system is stabilizing. Thus, a stationary state toward which all optimal trajectories must converge is defined. This extends to this class of models, the co‐called turnpike property of optimal economic growth models.
A Numerical method for optimization of distributed parameter structures with displacement constraints
Authors: Haug Edward J. 
Published: July 2010

AbstractRecent results in design differentiation of structural displacement are used to develop an iterative optimization method that explicitly treats bounds on the maximum displacement of structural elements. Computable design derivative expressions are employed, and a finite‐element computational algorithm is presented for obtaining design derivatives needed in structural optimization. A function‐space, gradient‐projection, optimization technique which uses these derivatives is presented. The method is applied to beam and plate optimization problems to illustrate its use and to evaluate its computational efficiency. Results obtained using this method are compared with solutions reported in the literature. The method is shown to be both generally applicable and numerically efficient.
Program CC's implementation of the wiener‐hopf lqg optimal control problem
Authors: Thompson Peter M. 
Published: July 2010

AbstractThe linear quadratic Gaussian (LQG) optimal control problem of single‐input‐single‐output (SISO) analogue and digital systems can be solved using Wiener‐Hopf techniques of spectral and partial factorization. A new form of the Wiener‐Hopf result is derived, followed by a description of how the solution is implemented in Program CC, a user‐friendly, command driven, computer‐aided‐control‐system‐design (CACSD) package.
Optimal expansion of the canadian tar sands industry
Authors: Dupont Serge , Fuller J. David 
Published: July 2010

AbstractOur model minimizes the discounted cost of meeting projected Canadian oil demand from the currently inexpensive but limited conventional oil, more expensive tar sands and still more expensive imports. We limit the rates of increase of the three sources of supply and impose non‐negativity constraints on two of the state variables, conventional supply and imports. The optimal control is generalized bang‐bang, but the set of extreme points depends on the status of the state constraints. All possible optimal sequences of extreme point controls are determined. Implications for tar sands development policy are discussed, along with economic interpretations and additions to the theory of exhaustible resources.
Self‐tuning control of bilinear systems
Authors: Burnham K. J. , James D. J. G. , Shields D. N. 
Published: July 2010

AbstractIn this paper, a self‐tuning pole‐placement control algorithm is proposed for a class of single‐input‐single‐output bilinear systems. Use is made of a time‐step quasi‐linearization procedure, within an extended state‐space framework, recursively updated in order to implement a suboptimal pole‐placement control strategy.Use of a two‐tier adaptive mechanism is proposed within the recursive estimation procedure and involves the use of variable forgetting factor reset coupled with covariance reset. Simulation studies indicate that this approach gives rise to increased alertness and adaptivity of the self‐tuner, leading to improved performance in terms of both system stability and parameter tracking ability.
Efficiency‐optimized speed control system in separately excited DC‐motor drives—performance index method
Authors: Egami Tadashi , Kanamori Yu Kihiro , Tsuchiya Tak Eshi 
Published: July 2010

AbstractThis paper proposes a synthesis method for an efficiency‐optimized speed control system using a performance index including loss term. Since the performance index almost includes the loss term at the steady state, suboptimal efficiency is obtained. The speed response is controlled by tuning the values of the weighting factors at the transient state. The effectiveness is shown in simulation and experimental studies, and the system is more efficient than the usual control systems with constant field excitation.
Critical control weighting for non‐minimum‐phase stochastic control systems
Authors: Lim C. C. , Hang C. C. , Leong K. Y. 
Published: July 2010

AbstractBecause of its capability of handling non‐minimum‐phase zeros and its simplicity in digital implementation, the generalized minimum‐variance control strategy has been used extensively in the design of stochastic digital control systems. However, the choice of a suitable control weighting factor within the performance index is not always straightforward and very often designers have to rely on a trial‐and‐error approach. This paper establishes conditions on the limits of the weighting factor for closed‐loop stability. Expressions for computing exactly the minimum stability value of control weighting for processes modelled by a dead time plus a rational transfer function of up to fourth order are derived.
Discrete‐time optimal control of an economic system using different objective functions
Authors: Sandblom C.‐L. , Eiselt H. A. , Jörnsten K. O. 
Published: July 2010

AbstractIn most applications of optimal control of econometric models, the objective (welfare cost) functions employed are quadratic, although some authors have suggested linear functions. One reason for choosing the quadratic objective function is that with linear system dynamics, the optimal trajectories can easily be computed by using the Riccati equation approach. With a linear objective function and with constraints on the control and/or the state variables, large‐scale linear programming techniques can be used instead of the Riccati equation to obtain optimal trajectories.In this paper, not only piecewise quadratic but also piecewise linear minimax‐and entropy‐type objective functions are considered. As an illustration, the 35‐equation CLEAR model of Canada is optimized with various of these objective functions and the results are then compared. The relative merits of the different approaches are discussed from an economic policy point of view. Algorithmic and numerical solution aspects are also addressed.
An incentive‐compatible resource allocation problem allowing collusion
Authors: Chiu Samuel S. , Lin Qing 
Published: July 2010

AbstractThis paper extends recent results on an incentive‐compatible modification of the Heal algorithm for resource allocation. Previous research has shown, under some assumptions, that the participants can be induced to report the truth in their own interest so as to achieve a group optimum. Using the same modified procedure, we show that if we allow secret collusion among users, participants can be induced to report quasi‐accurate information in their own interest so as to achieve a group optimum. The instantaneous convergence rate (in terms of a Lyapunov function) is faster when we allow collusion.
Well‐posedness of a model order reduction for singularly perturbed linear stochastic systems
Authors: Gajic Zoran 
Published: July 2010

AbstractAn order reduction problem for the state estimation of singularly perturbed linear systems is shown to be a well‐posed problem, whereas the corresponding order reduction control problem is ill‐posed. This observation plays an important role in the concept of multimodeling and in the slow—fast decomposition control problem for singularly perturbed linear stochastic systems.
Stochastic two‐target pursuit‐evasion differential games in three dimensions
Authors: Yavin Y. , Miloh T. 
Published: July 2010

AbstractStochastic versions of a three‐dimensional two‐target ‘game of two cars’ and a three‐dimensional two‐target ‘homicidal chauffeur’ game are considered. These are used to model a dogfight, in the (x, y, z) space, between a very agile player Q and a less manoeuvrable player P. A numerical study is conducted, by numerically solving a non‐linear partial differential equation, to investigate the role of the parameters of manoeuvrability, speed and the performance of the ‘weapon systems’ in the encounter.
Sliding‐horizon optimal and certainty‐equivalent controllers for stabilizing stochastic‐parameter systems
Authors: Yaz Engin 
Published: July 2010

AbstractThis paper introduces novel control schemes to stabilize linear discrete stochastic‐parameter systems. It is shown that under some mild conditions, controllers that are optimal in the sense of minimizing a finite sliding‐horizon performance index subject to linear stochastic‐parameter system constraint are stabilizing for the system in both senses of almost‐sure and mean‐square asymptotic stability. Moreover, if the uncertainties of stochastic parameters are small enough, the designer can even stabilize these systems by the use of controllers that are designed on the basis of the deterministic equivalent of these systems.
On Applications of a new method for computing optimal non‐linear feedback controls
Authors: Bourdache‐Siguerdidjane Houria 
Published: July 2010

AbstractA new method of computing optimal non‐linear feedbacks is used for regulating the angular momentum of spacecraft using both reaction jets and flywheels. It is shown that the optimal feedback law satisfies a system of first‐order, quasi‐linear, partial differential equations. The integration of these equations by the method of characteristics gives the non‐linear feedback control. This control reduces the angular velocities of the space vehicle to zero by minimizing the fuel consumption.The optimal regulation, under reaction jet control alone and with the flywheels at fixed angular velocities, is considered. The special case where these velocities are zero leads readily to the known analytical solution of the feedback law, which is linear in the state although the dynamics is non‐linear.
Distributed control of layered orthotropic plates with damping
Authors: Adali S. , Sadek I. S. , Sloss J. M. , Bruch J. C. 
Published: July 2010

AbstractOptimal control of a composite rectangular plate on an elastic foundation is studied with the objective of minimizing its dynamic response in a given period of time with the minimum possible expenditure of force. The plate undergoes transient vibrations starting from specified initial displacement and velocity distributions, and the control is exercised by optimally determining the transverse distributed force. The multiple objectives of the problem are taken into account by adopting a vector performance criterion comprising quadratic functional of the deflection, velocity and distributed force. The sufficiency condition of optimality is derived using control theory results which lead to an analytic solution of the problem. Numerical results are given for simply supported plates made of specially orthotropic layers of boron‐fibre‐reinforced plastic material. It is demonstrated that the effectiveness of the proposed control depends on the lamination order, foundation modulus, viscous damping, aspect ratio and terminal time as well as on the weight factors attached to various cost functionals.
Optimal transmission and jamming strategies in a communication channel
Authors: Cassandras Christos G. 
Published: July 2010

AbstractA zero‐sum differential game model is presented for two players who are both transmitting information and jamming their opponent at the same time, under channel capacity constraints. The problem for each player is to find an optimal policy for allocating this capacity over the duration of the game. Given a cost function for the game, conditions are determined under which equilibrium strategies exist. These (pure) strategies are found to be of the bang‐bang variety and depend on game parameters such as the channel capacity and jamming effectiveness of the players, as well as the duration of the game.
Optimization of freeway traffic control problems
Authors: Mahmoud Maodi S. , Eid Shawki Z. 
Published: July 2010

AbstractThe problem of optimal freeways traffic control is described by a detailed non‐linear discrete‐time model. A four‐level hierarchical algorithm is developed to compute the optimal control strategies. Simulation results indicate the efficiency of the developed algorithm in bringing congested traffic flow back to normal operation.