bluuebunny/crossref_metadata_2025_split huggingface dataset:
A hierarchical approach to optimized control of water distribution systems: Part I decomposition
Authors: Coulbeck B. , Brdyś M. , Orr C. H. , Rance J. P. 
Published: July 2010

AbstractConsideration is given to the problem of evaluating optimized control schedules for common types of water distribution systems. For these systems the major operating costs are associated with electricity charges for pumped source supplies. This paper provides a rigorous formulation for system operations. Proposals are then made for hierarchical decomposition into these levels: an upper level for dynamic optimization of reservoir storage, an intermediate level for static optimization of source extraction and a tower level for static optimization of individual sources.
Variational method for the distributed control of a vibrating beam
Authors: Sadek I. S. 
Published: July 2010

AbstractThe problem of damping out the oscillations of a simply supported beam subject to viscous damping is solved analytically by employing a maximum principle. The basic control problem is to minimize the deflection and the velocity of displacements in a given period of time with the minimum possible expenditure of force. The multiobjective problem is scalarized by using a linear combination of the criteria. This problem is also solved by two heuristic approaches: a direct method and an integral equation approach.
Stability analysis of adaptive systems: An Approach based on controller structure optimality
Authors: Ortega R. 
Published: July 2010

AbstractIn this paper we approach the problem of establishing stability conditions for adaptive controllers from a different perspective: namely, we are interested in knowing when a controller structure that minimizes a linear quadratic criterion can be adaptively implemented to ensure global stability. The main result is the proof that, for systems of relative degree zero, controller structures that solve the linear quadratic optimal control (LQOC) problem1 are globally stable when the parameters are adaptively updated. Interestingly enough, no positive realness or matchability assumption is required to establish the result.
A Boundary element method based on cauchy integrals for some linear quadratic boundary control problems on a circle
Authors: Chen Goong , Chen Chiang‐Pu , Aronov Irina 
Published: July 2010

AbstractFor certain types of elliptic boundary control problems, the boundary element method has considerable advantage over the traditional finite element or finite difference methods because of the reduction of dimensionality in computations. In this paper we examine a variant of such boundary integral methods based on Cauchy integrals. The cost functional here contains only finitely many quadratic terms related to sensory data at those finite interior points. We see that the numerical efficiency of this approach hinges largely on the complexity of the inverse of a certain boundary integral operator. In the case of a circle, such an inverse is readily obtainable and entire computations require only a small effort to yield useful numerical information about the optimal control. Other general situations are also discussed.
A Hierarchical approach to optimized control of water distribution systems: Part II. Lower‐level algorithm
Authors: Coulbeck B. , Brdys M. , Orr C. H. , Rance J. P. 
Published: July 2010

AbstractConsideration is given to the lower level of a hierarchical optimization structure for evaluating optimized control schedules for common types of water distribution systems. The structure is presented in Part I. The lower‐level optimization problem involves independent optimization of a number of generalized pump stations. This requires minimization of individual pump station consumed power. An algorithm for the pump station power minimization is proposed and its convergence and optimality properties are investigated. The algorithm is tested over a range of physical data. Typical results are presented, which include comparisons with an alternative solution method.
Optimal shape design and unilateral boundary value problems: Part I
Authors: Haslinger J. , Neittaanmäki P. , Tiihonen T. , Kaarna A. 
Published: July 2010

AbstractIn the first part we give a general existence theorem and a regularization method for an optimal control problem where the control is a domain in R″ and where the system is governed by a state relation which includes differential equations as well as inequalities. In the second part applications for optimal shape design problems governed by the Dirichlet‐Signorini boundary value problem are presented. Several numerical examples are included.
Feedback controllers for stochastic‐parameter systems: Relations among various stabilizability conditions
Authors: Yaz Engin 
Published: July 2010

AbstractIn this work we consider various feedback controllers designed for linear stochastic‐parameter discrete‐time systems. These controllers are derived by use of different system models (true system model and its deterministic equivalent) and different performance criteria (infinite horizon and finite moving horizon) to stabilize the same class of systems. It is shown that sufficient conditions for almost‐sure and mean‐square stabilizability by these controllers are closely related.
A Boundary value technique for solving singularly perturbed, fixed end‐point optimal control problems
Authors: Kadalbajoo Mohan K. , Singh Arindama 
Published: July 2010

AbstractA method is proposed to solve fixed end‐point, linear optimal control problems with quadratic cost and singularly perturbed state. After translating the problem into a two‐point boundary value problem, we choose two points t1, t2 ϵ [t0, tf] and let τ = (t‐t0)/ϵ and σ = (tf‐t)/ϵ. The τ‐scaled, original and σ‐scaled boundary value problems are then solved on the intervals [t0, t1], [t1, t2] and [t2, tf] respectively. A test example is solved to illustrate the method.
Adsorption of aqueous Hg (II) by a novel poly(aniline‐co‐o‐aminophenol)/mesoporous silica SBA‐15 composite
Authors: Tang Rong , Li Qin , Cui Hao , Zhang Ya , Zhai Jianping 
Published: July 2010

AbstractA novel poly(aniline‐co‐o‐aminophenol) (PAOA)/mesoporous silica SBA‐15 nanocomposite was synthesized and investigated for adsorption of Hg (II) from aqueous solutions of wide pH range. A chemical oxidation method was employed for polymerization of aniline and o‐aminophenol on an ordered SBA‐15 template to obtain a significantly enlarged BET surface area of the adsorbent. Efficiency study revealed that the PAOA/SBA‐15 could reach a maximum Hg (II) adsorption capacity of over 400 mg/g. Kinetic study showed that the Hg (II) adsorption by the PAOA/SBA‐15 fitted a pseudo‐second‐order kinetic model, indicating that the mercury adsorption process was predominantly controlled by chemical process. The results of this study also proved that the adsorbed Hg (II) could be effectively desorbed from the PAOA/SBA‐15 in 0.1M HCl and 5% sulfocarbonide solutions. Associated adsorption mechanism was also investigated by means of Fourier transform infrared (FTIR) and X‐ray photoelectron spectroscopy (XPS) techniques. Copyright © 2010 John Wiley & Sons, Ltd.
Ausflug in die Vergangenheit: Chinin und andere Chinaalkaloide 2. Teil: Die Aufklärung des räumlichen Baus der Chinolin‐Chinaalkaloide
Authors: Eiden Fritz 
Published: July 2010

AbstractSchon im frühen 19. Jahrhundert wurden die wichtigsten Chinaalkaloide isoliert. Zum Nachweis und zur Konstitutionsaufklärung des Chinolinanteils der Alkaloide brauchte man mehr als fünf Jahrzehnte und erst um die Jahrhundertwende kam man der Chinuclidingruppe auf die Spur. 1907 schließlich konnte das Problem der Verknüpfung der Chinolin‐ mit der Chinuclidingruppe gelöst und so die Konstitution der Chinaalkaloide endgültig geklärt werden. Doch damit war das Ziel der mühsamen Wanderung noch lange nicht erreicht: Für die Analyse der Raumstruktur von Chinin, Cinchonin und ihrer Stereoisomeren wurden weitere vierzig Jahre benötigt.
The comparison of the behaviors of polymer/clay nanocomposites based on high density polyethylene and polypropylene in exposure of electron‐irradiation
Authors: Mohaddespour Ahmad , Ahmadi Seyed Javad , Abolghasemi Hossein 
Published: July 2010

AbstractThe effect of irradiation on thermal and mechanical properties of high density polyethylene (HDPE) and polypropylene (PP)/clay nanocomposites in the presence of polyethylene glycol (PEG) and polypropylene glycol (PPG) for enhancing the clay dispersion into the polymer matrices is considered. The morphology studies show that clay layers satisfactorily expand in the presence of compatibilizers. The irradiation improves the mechanical properties of HDPE nanocomposites at 500 kGy, but it decreases the tensile strength of PP nanocomposites. The addition of PEG markedly ameliorates the mechanical properties of HDPE nanocomposites at 500 kGy, while this improvement is not deduced for PP nanocomposites. The thermogravimetric analysis data show that the irradiation increases the thermal stability of HDPE nanocomposites at the clay content of 5 wt% with and without compatibilizer. The thermal stability of PP nanocomposites descends with the irradiation dose, and the presence of PPG into the PP matrix intensifies this reduction. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Inferential closed‐loop control of particle size and molecular weight distribution in emulsion polymerization of styrene
Authors: Vafa Ehsan , Shahrokhi Mohammad , Abedini Hossein 
Published: July 2010

AbstractIn this work, simultaneous inferential control of particle size distribution (PSD) and molecular weight distribution (MWD) in a semi‐batch emulsion polymerization reactor of styrene has been addressed. Using a comprehensive dynamic model for PSD and MWD predictions and performing a sensitivity analysis, it has been revealed that free surfactant and chain transfer agent (CTA) concentrations in the reactor are the most suitable candidates for inferential control of PSD and MWD, respectively. To control concentrations of these species in the reactor, their inlet feed flow rates are used as manipulated variables. It is assumed that the concentration of CTA is measured infrequently and therefore an open‐looped observer, based on the reaction calorimetry, has been designed to estimate the CTA concentration. The infrequent measurements of CTA concentration are used to correct its estimation. As the online measuring of the ionic free surfactant concentration is also difficult, solution conductivity which is a good indication of free surfactant concentration is used for control purposes. Simulation results show that the performance of the proposed control scheme is satisfactory even in the presence of model mismatch. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Improved mechanical properties of poly(ethylene terephthalate) nanocomposite fibers
Authors: Litchfield David W. , Baird Donald G. , Rim Peter B. , Chen Chen 
Published: July 2010

AbstractImprovements in Young's modulus and strength (tenacity) of poly(ethylene terephthalate) (PET) fibers were obtained by drawing unoriented nanocomposite filaments containing low concentrations (<3 wt%) of various organically modified montmorillonites (MMTs) in a second step at temperatures above the glass transition. Prior to melt spinning, solid‐state polymerization was used to rebuild lost molecular weight, due to MMT‐induced degradation, to a level suitable for producing high strength fibers. Greater improvements in mechanical properties occurred when the MMT stacks were intercalated with PET. A nominal 1 wt% loading of dimethyl‐dehydrogenated tallow quaternary ammonium surface modified MMT in drawn PET fiber showed a 28% and 63% increase in Young's modulus and strength, respectively. Relative to an unfilled PET fiber, these results surpassed the upper bound of the rule of mixtures estimate and suggested that both the type of surface modification and concentration of MMT affect the degree of PET orientation and crystallinity. Furthermore, drawability above Tg and elongation at break increased upon the addition of organically modified MMT to unoriented PET fibers, which was a key distinction of this work from others examining similar systems. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Effect of side chain length on the glass transition of copolymers from styrene with n‐alkyl citraconimides and with n‐alkyl itaconimides
Authors: Cowie J. M. G. , Reid V. M. C. , Mcewen I. J. 
Published: July 2010

AbstractEquimolar copolymers of styrene with a series of N‐n‐alkyl citraconimides where the alkyl group varies from methyl to octadecyl were synthesised and the dependence of the glass transition on the length of the alkyl chain examined. Over the series N‐methyl to N‐n‐octadecyl only a smooth monotonic decrease in the value of the glass transition temperature Tg was found. Any increase in Tg at high alkyl chain lengths that might arise from ordering effects was not detected. However, by viewing the copolymer structure as comprising a main chain unit and a series of methylene side chain units of varying length, then plotting the data according to the Gordon‐Taylor equation, a deviation from linearity is revealed that may be interpreted as due to incipient crystallisation of the longer side chains.A similar examination of a series of copolymers of styrene with N‐n‐alkyl itaconimides proved impracticable due to the inability to prepare isomerically pure itaconimide monomers. Comparisons of the citraconimide series were thus drawn with literature data on copolymers of styrene with N‐alkyl maleimides.
Non‐Gaussian effects in styrene‐butadiene rubber
Authors: Doherty William O. S. , Leè Kim L. , Treloar Leslie R. G. 
Published: July 2010

AbstractSimultaneous measurements of stress and birefringence were made on a vulcanized styrene‐butadiene rubber (SBR) at 0°, 15° and 25°C. The stress‐strain curves at all temperatures showed a strong upward deviation from the Gaussian statistical theory at high extensions which became more pronounced with decreasing temperature due to the increasing extension to break. The birefringence, however, was substantially of the form predicted by the Gaussian theory. Comparison studies on natural rubber under similar conditions of experiment showed birefringence and hysteresis effects which could be interpreted on the basis of strain‐induced crystallisation (as revealed by X‐rays). Such effects were completely absent in the SBR samples which also showed no evidence of crystallisation on X‐ray examination in the stretched state. It is concluded that the upturn in stress‐strain curve in both materials is primarily due to the limited extensibility of the network, as treated in the non‐Gaussian statistical theory, and that crystallisation, when present, plays only a subsidiary role.
Insights in Molecular Structure of Organosilicon Plasma Polymer Produced by Means of Atmospheric Pressure Dielectric Barrier Discharge Process
Authors: Bour Jérôme , Charles Laurence , Petersen Julien , Michel Marc , Bardon Julien , Ruch David 
Published: July 2010

AbstractMost of polymers resulting from plasma polymerization exhibit a structure, which is very complex and different from those synthesized by conventional polymerization methods. The molecular structure of such plasma polymers is difficult to assess, but its characterization is a crucial issue. Mass spectrometry (MS) seems to be a promising analytical approach to get this molecular information. The chemical structure of a ppHMDSO (plasma polymer HexaMethylDiSiloxane) film, deposited by means of atmospheric pressure dielectric barrier discharge process, has first been characterized by means of FTIR spectroscopy. Additional insights in the polymer structure were provided by mass spectrometric techniques. MALDI‐TOF‐MS and ESI‐Q‐TOF‐MS analyses were carried out to obtain information on high molecular weight oligomers and/or small polymers collected in the THF soluble fraction of a ppHMDSO film. Although uncertainty still remains about the detected species, it could be concluded they were copolymers such as poly(dimethylsiloxane‐co‐methylsiloxane) or poly(dimethylsiloxane‐co‐SiO2) with a number of monomers up to 20, and some structures could be proposed for the end groups.magnified image
The three‐dimensional structure of the first EGF‐like module of human factor IX: Comparison with EGF and TGF‐α
Authors: Baron M. , Norman D.G. , Harvey T.S. , Campbell I.D. , Handford P.A. , Mayhew M. , Brownlee G.G. , Tse A.G.D. 
Published: July 2010

AbstractThe three‐dimensional structure of the first epidermal growth factor (EGF)‐like module from human factor IX has been determined in solution using two‐dimensional nuclear magnetic resonance (in the absence of calcium and at pH 4.5). The structure was found to resemble closely that of EGF and the homologous transforming growth factor‐α (TGF‐α). Residues 60–65 form an antiparallel β‐sheet with residues 68–73. In the C‐terminal subdomain a type II β‐turn is found between residues 74 and 77 and a five‐residue turn is found between residues 79 and 83. Glu 78 and Leu 84 pair in an antiparallel β‐sheet conformation. In the N‐terminal region a loop is found between residues 50 and 55 such that the side chains of both are positioned above the face of the β‐sheet. Residues 56–60 form a turn that leads into the first strand of the β‐sheet. Whereas the global fold closely resembles that of EGF, the N‐terminal residues of the module (46–49) do not form a β‐strand but are ill‐defined in the structure, probably due to the local flexibility of this region. The structure is discussed with reference to recent site‐directed mutagenesis data, which have identified certain conserved residues as ligands for calcium.
Sequence and expression of the gene for N10‐formyltetrahydrofolate synthetase from Clostridium cylindrosporum
Authors: Rankin Carolyn A. , Haslam Gale C. , Himes Richard H. 
Published: July 2010

AbstractSau3 A and Hind III restriction fragments of Clostridium cylindrosporum genomic DNA were used to isolate clones containing 80% of the N10‐H4folate synthetase gene in a 5′ fragment and the remaining 20% of the gene in the 3′ fragment. These fragments were joined at a common SnaB I restriction site and expressed in Escherichia coli at a level equivalent to what is normally found in C. cylindrosporum. Sequence comparisons show a large degree of homology with genes from two other clostridial species, including a thermophile. Certain conserved sequences found in the three clostridial proteins and in the N10‐H4folate synthetase portion of eukaryotic Cl‐H4folate synthases may represent consensus sequences for nucleotide and H4folate binding.
Crevice‐forming mutants of bovine pancreatic trypsin inhibitor: Stability changes and new hydrophobic surface
Authors: Kim Key‐Sun , Tao Feng , Fuchs James , Woodward Clare , Danishefsky Avis T. , Housset Dominique , Wlodawer Alexander 
Published: July 2010

AbstractFour mutants of bovine pancreatic trypsin inhibitor (BPTI) with replacements in the rigid core result in the creation of deep crevices on the surface of the protein. Other than crevices at the site of the mutation, few other differences are observed in the crystal structures of wild‐type BPTI and the mutants F22A, Y23A, N43G, and F45A. These mutants are highly destabilized relative to wild type (WT). The differences between WT and mutants in the free energy change associated with cooperative folding/unfolding, ΔΔG0(WT→mut), have been measured by calorimetry, and they are in good agreement with ΔΔG0(WT→mut) values from hydrogen exchange rates. For F22A the change in free energy difference is about 1.7 kcal/mol at 25 °C; for the other three mutants it is in the range of 5–7 kcal/mol at 25 °C. The experimental ΔΔG0(WT→mut) values of F22A, Y23A, and F45A are reasonably well accounted for as the sum of two terms: the difference in transfer free energy change, and a contribution from exposure to solvent of new surface (Eriksson, A.E., et al., 1992, Science 255, 178–183), if the recently corrected transfer free energies and surface hydrophobicities (De Young, L. & Dill, K., 1990, J. Phys. Chem. 94, 801–809; Sharp, K.A., et al., 1991a, Science 252, 106–109) are used and only nonpolar surface is taken into account. In N43G, three protein–protein hydrogen bonds are replaced by protein–water hydrogen bonds. The value of ΔΔG0(WT→mut) computed from model transfer free energies and surface hydrophobicities is 4.0 kcal/mol less than observed, consistent with reports that one hydrogen bond contributes about 1.3 kcal/mol of stabilizing free energy (Shirley, B.A., et al., 1992, Biochemistry 31, 725–732).
Crystal structure of recombinant human triosephosphate isomerase at 2.8 Å resolution. Triosephosphate isomerase‐related human genetic disorders and comparison with the trypanosomal enzyme
Authors: Mande Shekhar C. , Hol Wim G.J. , Mainfroid Véronique , Goraj Karine , Martial Joseph A. , Kalk Kor H. 
Published: July 2010

AbstractThe crystal structure of recombinant human triosephosphate isomerase (hTIM) has been determined complexed with the transition‐state analogue 2‐phosphoglycolate at a resolution of 2.8 Å. After refinement, the R‐factor is 16.7% with good geometry. The asymmetric unit contains 1 complete dimer of 53,000 Da, with only 1 of the subunits binding the inhibitor. The so‐called flexible loop, comprising residues 168‐174, is in its “closed” conformation in the subunit that binds the inhibitor, and in the “open” conformation in the other subunit. The tips of the loop in these 2 conformations differ up to 7 Å in position. The RMS difference between hTIM and the enzyme of Trypanosoma brucei, the causative agent of sleeping sickness, is 1.12 Å for 487 Cα positions with 53% sequence identity. Significant sequence differences between the human and parasite enzymes occur at about 13 Å from the phosphate binding site. The chicken and human enzymes have an RMS difference of 0.69 Å for 484 equivalent residues and about 90% sequence identity. Complementary mutations ensure a great similarity in the packing of side chains in the core of the β‐barrels of these 2 enzymes. Three point mutations in hTIM have been correlated with severe genetic disorders ranging from hemolytic disorder to neuromuscular impairment. Knowledge of the structure of the human enzyme provides insight into the probable effect of 2 of these mutations, Glu 104 to Asp and Phe 240 to Ile, on the enzyme. The third mutation reported to be responsible for a genetic disorder, Gly 122 to Arg, is however difficult to explain. This residue is far away from both catalytic centers in the dimer, as well as from the dimer interface, and seems unlikely to affect stability or activity. Inspection of the 3‐dimensional structure of trypanosomal triosephosphate isomerase, which has a methionine at position 122, only increased the mystery of the effects of the Gly to Arg mutation in the human enzyme.