bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantized feedback control for linear uncertain systems
Authors: Fu Minyue , Xie Lihua 
Published: May 2009

AbstractThis paper studies robust control problems under the setting of quantized feedback. We consider both the static and dynamic logarithmic quantizers. In the static quantization case, the quantizer has an infinite number of levels, and the design problem is to find the minimal quantization density required to achieve a given control objective. In the dynamic quantization case, the problem is to minimize the number of quantization levels to achieve a given control objective. We present a number of results for different controller‐quantizer configurations. These results are developed using the so‐calledsector bound approachfor quantized feedback control, which was initiated by the authors previously for systems without uncertainties. Copyright © 2009 John Wiley & Sons, Ltd.
Performance evaluation of IKEv2 authentication methods in next generation wireless networks
Authors: Faigl Zoltán , Lindskog Stefan , Brunstrom Anna 
Published: May 2009

AbstractSecure communications have a key role in future networks and applications. Information security provisions such as authorization, authentication, and encryption must be added to current communications protocols. To accomplish this, each protocol must be reexamined to determine the impact on performance of adding such security services. This paper presents an experimental evaluation of the performance costs of a wide variety of authentication methods over IKEv2 in real and partly emulated scenarios of next generation wireless networks. The studied methods are pre‐shared keys (PSKs), extensible authentication protocol (EAP) using MD5, SIM, TTLS‐MD5, TLS, and PEAP‐MSCHAPv2. For the EAP‐based methods, RADIUS is used as the authentication, authorization, and accounting (AAA) server. Different lengths of certificate chains are studied in case of the TLS‐based methods, i.e., TTLS‐MD5, TLS, and PEAP‐MSCHAPv2. The paper first presents a brief overview of the considered authentication methods. Then, a comparison of the costs for message transfers and computations associated with the authentication methods is provided. The measurement results are verified through a simple analysis, and interpreted by discussing the main contributing factors of the costs. The measurement results illustrate the practical costs involved for IKEv2 authentication, and the implications of the use of different methods are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
The tensile properties of HNO3‐treated carbon fiber reinforced ABS/PA6 composites
Authors: Li J. , Zhang Y. F. 
Published: May 2009

AbstractIn this study, acrylonitrile‐butadiene‐styrene (ABS) terpolymer was reinforced with HNO3‐treated short carbon fibers (SCFs) [(hollow carbon fibers (HCFs)]. The effects of HCF concentration on the tensile properties of the composites were examined. Increasing the HCF concentration in the ABS matrix from 10 to 30 wt% resulted in improved tensile strength and tensile modulus. To obtain a strong interaction at the interface, polyamide 6 (PA6) at varying concentrations was introduced into the ABS/10 wt% SCF composite. The incorporation and increasing amount of PA6 in the composites increased tensile properties of the ABS/PA6/HCF systems due to the improved adhesion at the interface, which was confirmed by the ratio of tensile strength as an adhesion parameter. These results were also supported by scanning electron micrographs of the ABS/PA6/HCF composites, which exhibited an improved adhesion between the SCFs and the ABS/PA6 matrix. Copyright © 2009 John Wiley & Sons, Ltd.
Influence of coupling agent chain lengths on interfacial performances of carbon fiber and polyarylacetylene resin composites
Authors: Jiang Z. X. , Liu L. , Huang Y. D. , Ren H. 
Published: May 2009

AbstractThe influence of chain lengths on interfacial performances of carbon fiber/polyarylacetylene composites was studied. For this purpose, four coupling agents, methyltrimethoxysilane, propyltrimethoxysilane, octyltrimethoxysilane and dodecyltrimethoxysilane, were grafted onto fiber surface to obtain different chain lengths. The resulting carbon fiber surface was characterized by XPS and dynamic contact angle test. Interfacial adhesion in the resulting fiber reinforced polyarylacetylene resin composites was also evaluated by fracture morphology analysis and interfacial shear strength test. It was found that the interfacial adhesion in composites greatly increased with chain lengths on fiber surface. The improvement of interfacial adhesion was attributed to the interaction between the chain of coupling agents on fiber surface and that of polyarylacetylene resin at the interface. Copyright © 2009 John Wiley & Sons, Ltd.
Metallleichtbaukonstruktionen: Früher und heute
Authors: Pöter Hans 
Published: May 2009

AbstractDie Metallleichtbauweise blickt in Europa auf eine vergleichsweise kurze und dennoch sehr erfolgreiche Entwicklung zurück. Ausgehend von der lang geübten Tradition, für untergeordnete Nutzungen von Gebäuden für Dach und Wand Pfannenbleche und Stahlwellelemente einzusetzen, beginnt erst in der Mitte des letzten Jahrhunderts das Bauen mit Trapez‐ und Kassettenprofilen sowie Sandwichelementen aus Stahl‐ und Aluminiumblech. Der Fortschritt dieser neuartigen Bauweise geschieht in einem Maße, dass heute im Industrie‐ und Wirtschaftshochbau sowie in Teil en des öffentlichen Bauens kaum ein Dach ohne Metalltafeln auskommt und darüber hinaus eine schnell zunehmende Anzahl von Wandaufbauten ebenfalls Metalltafeln in den unterschiedlichsten Ausführungen aufweisen. Im Verlauf von nur etwa 60 Jahren ist es den Herstellern von dünnwandigen Bauteilen unter Verwendung hierfür angepasster Vormaterialien und Verbindungselemente und zusammen mit Planern und Verlegefirmen gelungen, das Baugeschehen in weiten Bereichen maßgeblich zu bestimmen.Light metal constructions: In the past and today.The light gauge metal construction industry in Europe faces a relatively short however very successful development. Based on a long lasting tradition in using corrugated metal sheet for roof and wall cladding for buildings meeting minor requirements the application of steel and aluminium trapezoidal and cassette sections as well as sandwich panels did not start until the middle of the past century. The progress of the new method of building roofs and walls took place in a way that today hardly any industrial building can do without metal panels in the roof. In addition there is a fast growing number of wall applications which contain metal panels out of a great variety of forms as well. In the course of just about 60 years fabricators of light gauge panels using modified raw materials and fasteners and in cooperation with architects and erection companies succeeded in taking over and controlling wide areas of applications in the building industry.
Selbsttragende und aussteifende Sandwichbauteile – Möglichkeiten für kleinere und mittlere Gebäude
Authors: Berner Klaus 
Published: May 2009

AbstractDie zur Zeit verwendeten Sandwichbauteile werden fast ausschließlich als raumabschließende Elemente für Wandverkleidungen und Dacheindeckungen eingesetzt. Dabei werden die Elemente stets auf eine tragende Unterkonstruktion montiert. Diese Elemente werden infolge äußerer Lasten sowie Temperatur‐ und Kriecheffekte ausschließlich durch Biegemomente und Querkräfte beansprucht.Zur Erweiterung der Marktchancen drängt sich die Frage auf, inwieweit Sandwichbauteile auch für lastabtragende Wände und aussteifende Scheiben ohne tragende Unterkonstruktion geeignet sind. Zur Beantwortung dieser Frage werden an drei unterschiedlichen Haustypen die maximalen Beanspruchungen von Wandpaneelen mit vertikalen Lasten (Normalkräften) und horizontalen Lasten (Scheibenkräften) ermittelt und den zu erwartenden Beanspruchbarkeiten gegenübergestellt. Dadurch kann gezeigt werden, dass die Verwendung von üblichen Sandwichbauteilen für lastabtragende und aussteifende Bauteile für kleinere bis mittlere Gebäude durchaus möglich ist.Self bearing and racking sandwich panels – possibilities for small and middle sized buildings.At the moment virtual all sandwich panels are used either as wall claddings or roof coverings. For this purpose the elements are mounted on a load‐bearing substructure. Due to external loads and effects from temperature and creep these elements are subjected to bending moments and shear forces only.The market for sandwich panels would be broadened if they could be used as load‐transferring walls and bracing diaphragms without load‐bearing substructure. Three different types of houses will be investigated in order to find out if sandwich panels are suitable for these applications. First maximum vertical (axial) loads of wall panels and horizontal loads (bracing) will be determined and then the values will be compared to expected load capacities. Thus it can be shown that commonly used sandwich panels are suitable for load‐transferring and bracing elements in small and medium‐sized buildings.
Tragfähigkeit perforierter dünnwandiger Bauteile
Authors: Misiek Thomas , Saal Helmut , Kathage Karsten 
Published: May 2009

AbstractDIN 18807‐1 und DIN 18807‐6 schließen die rechnerische Ermittlung der Tragfähigkeit perforierter Trapezprofile aus. Die diesbezüglichen Regelungen der EN 1993‐1‐3 und EN 1999‐1‐4 sind unzureichend und zum Teil irreführend. Im Rahmen eines Forschungsprojektes wurden daher die erforderlichen Regelungen für eine Erweiterung der genannten Normen um die Bemessung dünnwandiger Bauteile aus voll‐ und teilperforiertem Band oder Blechen erarbeitet.Design resistance of perforated trapezoidal sheeting.DIN 18807‐1 and DIN 18807‐6 exclude the design of perforated trapezoidal sheeting. The regulations of EN 1993‐1‐3 and EN 1999‐1‐4 concerning the design of perforated trapezoidal sheeting are insufficient and partly misleading. Therefore the stiffnesses, linear buckling loads and effective widths of thin‐walled components made of fully or partially perforated sheeting were investigated numerically and experimentally. The final result of this investigation are recommendations for the extension of the mentioned standards to apply them to fully or partially perforated sheeting.
Fassaden‐ und Dachkonstruktionen für ein Kernkraftwerk
Authors: Urban Hagen 
Published: May 2009

AbstractFür den Neubau eines Kernkraftwerkes mussten bei den Fassaden‐ und Dachkonstruktionen verschiedene besondere technische Aufgabenstellungen bewältigt werden. Diese sind zum einen in den lokalen klimatischen Verhältnissen begründet, zum anderen wird mit dem Neubau eines Kernkraftwerkes ein besonderer Anspruch hinsichtlich Betriebssicherheit verbunden. Die statisch‐konstruktiven Beanspruchungen, die Anforderungen aus der Bauphysik sowie die Montagebedingungen erforderten die Weiterentwicklung etablierter Fassadenaufbauten und deren Prüfung in Laboren und Prüfinstituten vor Fertigungsbeginn.Thema des Aufsatzes ist die bereits weitgehend realisierte Gebäudehülle des nichtnuklearen, konventionellen Bereiches – dem “Turbine Island“. Züblin Stahlbau GmbH, Mitglied des IFBS und DStV, führte im Turbine Island neben den Fassadenarbeiten auch die Stahlbauarbeiten aus. Aus der Verbindung beider Gewerke wurden Synergien insbesondere in der Planung der Schnittstellen und der Verzahnung von Montageabläufen vor Ort gezogen. In Summe werden beim Turbine Island ca. 90000 m2 Profilbleche verlegt und ca. 4000 t Stahlkonstruktionen montiert.Facade and roof construction for a nuclear power plant.For the new building of a nuclear power plant, different special technical problems are to be handled with regard to the facade and roof constructions. On the one hand, these are caused by the local climatic conditions, while on the other hand a special demand with regard to operational safety is associated with the new building of a nuclear power plant. The static‐construction demands, the requirements from the construction physics and as well as the erection conditions required the further development of established façade structures and their testing in laboratories and testing institutes before production commencement.The already largely realized building envelope of the conventional area – the “Turbine Island” – is the subject of this paper. Züblin Stahlbau GmbH, an IFBS and DStV member, also implemented the steel construction works in the Turbine Island, as well as the facade work. Synergies were generated from the combination of both trade sectors, in particular in the planning of the interfaces and the intermeshing of assembly process sequences on site. In sum, with the Turbine Island, approx. 90000 m2 profiled sheet metal units are laid and approx. 4000 tons steel structures mounted.
Dynamische Untersuchungen von leichten Stahldecken aus kaltgeformten, dünnwandigen Stahlprofilen
Authors: Lange Jörg , Rack Werner , Neujahr Martin 
Published: May 2009

AbstractLeichte Deckenkonstruktionen aus kaltgeformten, dünnwandigen Stahlprofilen mit einem Belag aus Holzfaserplatten oder ähnlichen Werkstoffen bieten viele Vorteile gegenüber den konventionellen Bauweisen. Hierzu zählen neben dem geringen Eigengewicht auch die einfache Ausführbarkeit und der hohe Vorfertigungsgrad. Gebäude können wirtschaftlich bei kurzer Bauzeit und einem hohen Qualitätsstandard durch wetterunabhängige Werksfertigung erstellt werden. Das geringe Gewicht qualifiziert sie darüber hinaus für Aufstockungen. Die Schwachstelle dieser Systeme kann jedoch in ihrem dynamischen Verhalten liegen.Ziel des nachstehend vorgestellten, derzeit laufenden Forschungsprojektes ist die Entwicklung eines hinsichtlich des dynamischen Verhaltens bei Anregung durch gehende Menschen optimierten Deckensystems aus kaltgeformten, dünnwandigen Stahlprofilen und einer Trockenbaulösung für die Deckenplatte. Erste Sondierungsversuche und numerische Untersuchungen wurden bereits durchgeführt. Nachstehend werden die bisher durchgeführten Untersuchungen vorgestellt, die Zusammenhänge erläutert und erste Ergebnisse qualitativ besprochen.Analysis of the dynamic behavior of lightweight floor systems supported by cold‐formed steel joists.Lightweight floor structures supported by cold‐formed steel joists with gypsum or wood‐based panels have a number of advantages compared to conventional construction methods. Among these advantages are the low weight and the high level of prefabrication. This construction method allows fast construction and a very high quality which is due to the weather‐independent production in the factory. Adding stories to existing buildings is also an application as a result of the light weight. The weakness of this system may be its dynamic behavior.The intention of our current research is to investigate the effects of human induced vibrations on lightweight ceiling systems made of cold‐formed steel joists to formulate new approaches to this problem. First steps of experimental investigations and numerical simulation were already realized. The following paper presents a documentation of the testing, exemplifies the correlation and discusses the first results.
A Novel Copolymer: Starch‐g‐Polyvinylpyrrolidone
Authors: Kahya Suat , Şanlı Oya , Ünal Halil İbrahim , Camurlu Pinar 
Published: May 2009

AbstractIn this study, graft copolymerization of N‐vinylpyrrolidone (N‐VP) onto starch was carried out in an aqueous medium using azobisisobutyronitrile (AIBN) as initiator. The variables affecting the graft copolymerization, such as monomer and initiator concentrations, reaction time and temperature, were thoroughly examined. In general, grafting of N‐vinylpyrrolidone onto starch increased with the increase in time and monomer concentration up to a certain value and then leveled off. Similarly, increase both in initiator concentration and temperature first favored and than impeded the grafting reaction. Optimum conditions established for grafting were as follows: N‐VP = 0.7 M, AIBN = 1.5×10‐3 M, T = 70°C and t = 5 h. Structural changes of the grafted starch were followed by FTIR, intrinsic viscosity and water absorption capacity studies.
Macromolecular Changes in Extruded Starch‐Films Plasticized with Glycerol, Water and Stearic Acid
Authors: Pushpadass Heartwin A. , Kumar Ajay , Jackson David S. , Wehling Randy L. , Dumais Joseph J. , Hanna Milford A. 
Published: May 2009

AbstractNative corn starch, plasticized with water, glycerol and stearic acid, was extruded in a conical twin‐screw extruder and sheeted into 0.4–0.6 mm thick films. The effects of extrusion and plasticizers on gelatinization, as well as the molecular and structural changes, in thermoplastic starch were analyzed. The onset and peak gelatinization temperatures of extruded starch varied from 42–46°C and 52.9–56.9°C, respectively, depending on the glycerol content. The enthalpy of gelatinization of extruded thermoplastic starch in excess water varied from 3.6–7.6 J/g, which also increased with plasticizer content. Amylose‐lipid complexes were formed during extrusion, and their enthalpies depended on the initial stearic acid and moisture contents. High‐performance size‐exclusion chromatography (HPSEC) data revealed that the starch underwent fragmentation during extrusion even under highly plasticized conditions, but the degradation was not severe as compared to previous findings. The relative percentages of amylopectin and amylose in native starch were 76.9 and 23.1%, respectively, which were changed to 71.3–76.6% and 23.4–28.7% in the extrudates. The average molecular weights of amylopectin and amylose in the extrudates ranged from 1.55×107–2.07×107 and 4.35×105–7.39×105, respectively. On the other hand, the molecular weights of amylopectin and amylose in native corn starch were observed as 2.27×107 and 4.68×105, respectively. Cross‐polarization magical angle spinning (CP/MAS) and high‐power decoupling (HP‐DEC) nuclear magnetic resonance (NMR) spectra of thermoplastic starch revealed the characteristics of amylomaize starch, confirming HPSEC results that the amylopectin macromolecules underwent fragmentation into amylose‐like fractions. In the extrudates, glycerol was found to be less mobile and entrained within the starch network.
Physicochemical Characteristics of Starches from Unripe Fruits of Mango and Banana
Authors: Espinosa‐Solis Vicente , Jane Jay‐lin , Bello‐Perez Luis A. 
Published: May 2009

AbstractMango and banana starches were isolated from unripe fruits and their morphology; thermal and pasting properties; molar mass and chain length distribution were determined. Mango starch granules were spherical or dome‐shaped and split, while banana starch had elongated granules with a lenticular shape. Amylopectin of both fruit starches had a lower molar mass than maize starch amylopectin; however, mango amylopectin had the highest gyration radius. Banana amylopectin showed the lowest percentage of short chains [degree of polymerization (DP) 6–12] and the highest level of long chains (DP ≥ 37); mango amylopectin presented the highest fraction of short chains, but the level of longest chains was intermediate between those of banana and maize amylopectins. Banana starch presented the highest average gelatinization temperature followed by mango starch and maize starch had the lowest value; a similar pattern was found for the gelatinization enthalpy. The two fruit starches had a lower pasting temperature than maize starch, but the former samples showed higher peak and final viscosities than maize starch. Structural differences identified in the fruit starches explain their physicochemical characteristics such as thermal and pasting behavior.
Treatment of early prostate cancer: active surveillance
Authors: O'Donnell Helen , Parker Chris 
Published: May 2009

AbstractWith the incidence of prostate cancer increasing, active surveillance aims to identify those men who need to be treated and those who can be safely left alone. The authors outline the rationale for active surveillance, describe how it is practised, and summarise the results of active surveillance studies reported to date. Copyright © 2009 Wiley Interface Ltd
A Pentacoordinate Chlorotrimethylsilane Derivative: A very Polar Snapshot of a Nucleophilic Substitution and its Influence on 29Si Solid State NMR Properties
Authors: Brendler Erica , Heine Thomas , Hill Anthony F. , Wagler Jörg 
Published: May 2009

AbstractThe reaction of 1‐methyl‐2‐mercaptoimidazole (methimazole) with chloromethyldimethylchlorosilane (ClCH2)Si(CH3)2Cl in the presence of triethylamine afforded the 1‐methylimidazol‐2‐ylthiomethyl‐substituted silane 1. The pentacoordinate silicon atom of 1 is housed within an almost trigonal bipyramidal coordination sphere, i.e., the three equatorially situated C–Si–C angles sum up to 359.5(3)°. The axial situation of the still Si‐bound chlorine atom with its remarkably long Si‐Cl separation of 2.5123(3) Å and a trans‐situated imidazolyl nitrogen donor constitute a very polar molecule, the resulting intermolecular interactions of which in the solid state were investigated crystallographically and by 29Si CP/MAS NMR spectroscopy. Single crystals of 1 revealed significantly lower susceptibility towards temperature changes along the crystallographic a‐axis, which is the axis along which chains of the polar molecules are aligned. Hence, the 29Si NMR shielding tensor, experimentally determined by CP/MAS NMR spectroscopy, could only be simulated to a satisfactory extent when taking these intermolecular interactions into account.
Chiral Dicopper Complexes with a Doubly Asymmetric Ligand as Models for the Tyrosinase Active Site: Synthesis, Structure, O2‐Reactivity and Comparison with Their Symmetric Analogs
Authors: Sander Ole , Näther Christian , Tuczek Felix 
Published: May 2009

AbstractIn order to model the asymmetric active site of the type‐3 copper enzyme tyrosinase the “doubly asymmetric” binucleating ligand 1‐[bis‐N,N‐(pyrid‐2‐ylmethyl)aminomethyl]‐3‐[N‐(pyrid‐2‐ylmethyl)‐N‐(2‐pyrid‐2‐ylethyl)aminomethyl]benzene (“unsDMPA”) is synthesized and coordinated to copper(I). The O2‐reactivity of the CuI(unsDMPA) complex and its analog derived from the symmetric counterpiece of unsDMPA, DMPA, is investigated. Oxygenation in methanol leads to dicopper(II) bis(μ‐hydroxo) and bis(μ‐methanolato) complexes; the dicopper(II) bis(μ‐hydroxo) complex of the unsDMPA ligand is chiral. Oxygenation in dichloromethane leads to oxidative N‐dealkylation. This is attributed to a tendency of DMPA and unsDMPA complexes to form dicopper bis(μ‐oxo) intermediates, as evidenced by DFT. The implications of these results with respect to the design of tyrosinase model systems are discussed.