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Design Rules (design + rule)
Selected AbstractsDesign Rules for Donors in Bulk-Heterojunction Solar Cells,Towards 10,% Energy-Conversion Efficiency,ADVANCED MATERIALS, Issue 6 2006C. Scharber For bulk-heterojunction photovoltaic cells fabricated from conjugated polymers and a fullerene derivative, the relation between the open-circuit voltage (Voc) and the oxidation potential for different conjugated polymers is studied. A linear relation between Voc and the oxidation potential is found (see figure). Based on this relation, the energy-conversion efficiency of a bulk-heterojunction solar cell is derived as a function of the bandgap and the energy levels of the conjugated polymer. [source] Establishing the Design Rules for DNA-Mediated Programmable Colloidal Crystallization,ANGEWANDTE CHEMIE, Issue 27 2010Robert DNA-programmierbare Kolloidkristalle werden aus 5,80,nm großen Nanopartikeln aufgebaut, und ihre Gitterparameter liegen zwischen 25 und 225,nm. Eine vorhersagbare und mathematisch definierbare Beziehung zwischen Partikelgröße und DNA-Länge bestimmt die Organisations- und Kristallisationsprozesse, was einen Satz von Regeln für die nanoskalige DNA-basierte Assoziatbildung liefert. [source] Fatigue behaviour of riveted Glare lap jointsFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9 2001L. Lazzeri Fibre metal laminates, such as Glare, are a family of materials with very interesting properties for fatigue-critical applications. This article describes the results of a research programme carried out to evaluate the fatigue and damage tolerance characteristics of riveted Glare lap joints, representative of fuselage longitudinal joints. The comparison with the behaviour of metallic joints shows that different contributions are made to the total fatigue life, with the crack propagation life being by far the longer one for the Glare material whereas the crack nucleation life covers almost the entire fatigue life for metallic joints. Design rules should take this peculiar behaviour into consideration, to achieve the maximum benefit in the use of this class of materials in fatigue-critical applications. [source] Structural fire design according to Eurocode 5,design rules and their backgroundFIRE AND MATERIALS, Issue 3 2005Jürgen KönigArticle first published online: 18 NOV 200 Abstract This paper gives a review of the design rules of EN 1995-1-2, the future common code of practice for the fire design of timber structures in the Member States of the EU and EFTA, and makes reference to relevant research background. Compared with the European pre-standard ENV 1995-1-2, the new EN 1995-1-2 has undergone considerable changes. Charring is dealt with in a more systematic way and different stages of protection and charring rates are applied. For the determination of cross-sectional strength and stiffness properties, two alternative rules are given, either by implicitly taking into account their reduction due to elevated temperature by reducing the residual cross-section by a zero-strength zone, or by calculating modification factors for strength and stiffness parameters. Design rules for charring and modification factors are also given for timber frame members of wall and floor assemblies with cavities filled with insulation. A modified components additive method has been included for the verification of the separating function. The design rules for connections have been systemized by introducing simple relationships between the load-bearing capacity (mechanical resistance) and time. The code provides for advanced calculation methods for thermal and structural analysis by giving thermal and thermo-mechanical properties for FE analyses. The code also gives some limited design rules for natural fire scenarios using parametric fire curves. Copyright © 2004 John Wiley & Sons, Ltd. [source] Microstrip dual-band bandpass filters using parallel-connected open-loop ring resonatorsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2008Lung-Hwa Hsieh Abstract This article proposes a microstrip dual-band bandpass filter that uses parallel-connected open-loop ring resonators. Compared to many microstrip dual-band filters, the advantages of using microstrip open-loop ring resonators are easy calculation (half-guided-wavelength), easy fabrication (equal width for all 50-, lines and without grounding holes), and direct connection to external feed lines (reducing insertion loss caused by gap couplings). Another advantage of the filter is an asymmetrical feed on the ring resonator that provides sharp rejections at its adjacent bands. The input and output matches of resonators to the external feed lines are derived using a simple transmission-line theory. The results of the derivation provide a simple design rule for filter designers. Simulated and measured results are presented with good agreement. The filter has minimum insertion loss of 1.25 dB at 1.85 GHz and 1.6 dB at 2.33 GHz. The 3-dB fractional bandwidths are 5.9% for the 1.9-GHz bandpass filter and 4.7% for the 2.4-GHz bandpass filter, respectively. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008. [source] A shorted square-ring slot antenna with a branched slot for the 1575 MHz and 2.4 GHz dual-band operationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009Chin-Long Tsai Abstract A shorted square-ring slot antenna with a branched slot is presented for the 1575 MHz and 2.4 GHz dual-band operations. This proposed antenna can be designed by two steps. First, the shorted square-ring slot antenna is designed for circular polarization in the GPS band. Then, a branched slot is added to the original structure to result linear polarization in the 2.4 GHz band. Because the added branched slot almost has no influence in the GPS band's characteristics, the design rule is very simple. The impedance and axial ratio bandwidths for the GPS band is 23.3% and 4.2%, respectively. Besides, the AR and antenna gain is 1.23 dB and 2.3 dBic at the frequency of 1575 MHz. The impedance bandwidth for the 2.4 GHz band is 4.5% and antenna gain at the center frequency of 2.445 GHz is 2.8 dBi. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 402,405, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24073 [source] A new three-dimensional 30 GHz bandpass filter using the LIGA micromachined processMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2001Kyoung-Youl Park Abstract In this letter, a new micromachined 3-D bandpass filter in the Ka-band is proposed using the LIGA process. The characteristic impedance and design parameters for the 3-D filter are determined from the experimental results and the filter design rule. The filter shows a wide-bandpass characteristic of 39%, with an insertion loss of 1.7 dB at 33.2 GHz, and can be applicable in high-power MMICs. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 199,201, 2001. [source] Bemessungsvorschlag für Holz/Beton-Verbundbalken unter Beachtung abgestufter VerbindungsmittelabständeBAUTECHNIK, Issue 3 2004Jörg Schmidt Dr.-Ing. Die Abstände der Verbindungsmittel von Holz/Beton-Verbundbalken werden i. allg. vorrangig aus Kostengründen entsprechend dem Querkraftverlauf abgestuft. Das Tragvermögen gemäß Bemessungsgrundlagen nach DIN 1052 bzw. EC 5 mit linear ermittelten Schnittgrößen (Näherungsverfahren/,-Verfahren) wird gegenüber Balken ohne die o. g. Abstufung deutlich reduziert. Da das tatsächliche Last-Verformungsverhalten jedoch deutliche Nichtlinearitäten aufweist und die Verbundsteifigkeit hinsichtlich des Tragvermögens nur einen geringen Einfluß besitzt, wird in diesem Beitrag der Einfluß der Abstufung der Verbindungsmittelabstände auf das Tragverhalten von Verbundbalken mittels nichtlinearer FE-Analysen untersucht. Im Ergebnis ist festzustellen, daß der Sicherheitsabstand zwischen Gebrauchslast gemäß E DIN 1052 und Versagenslastniveau mit zunehmendem Abstufungsgrad zunimmt, weil das tatsächliche Tragvermögen weniger , als durch das derzeitige Bemessungsmodell unterstellt , reduziert wird. Somit weisen also die Systeme, deren Verbinderabstände mehrmals abgestuft sind, den größten Sicherheitsabstand auf, könnten also noch wirtschaftlicher bemessen werden. Deshalb wird im Ergebnis der Untersuchungen ein neuer Bemessungsvorschlag unterbreitet und verifiziert, der die Nichtlinearitäten berücksichtigt, einen gleichmäßigen Sicherheitsabstand zum Versagenslastniveau gewährleistet und eine deutlich wirtschaftlichere Bemessung erlaubt. Design proposal for timber/concrete composite beams with graded connnector distances. The distance of connections of timber/concrete composite beams is often graded for economical reasons according the shear force distribution. The load-carrying capacity of composite beams according to DIN 1052 respectively E DIN 1052 with internal forces, which are linearly determined, (,-procedure) are clearly reduced compared to beams without graded distances of connectors. The actual load-bearing behaviour distinctly shows non-linearities. The influence of the gradations of the connectors on the load-bearing behaviour of composite beams is investigated, because the influence of the stiffness of connections on the load-bearing capacity of composite beams is small. The paper presents a comparison between failure loads determined by FE-analysis and the working loads according to the current design rule. It is shown that the decrease of load-bearing capacity is smaller than assumed by current code of practice. Structures with several different distances of connections have the largest safety-factor. These systems can more economically be designed. As the result of the investigations, a new design proposal is presented, which takes non-linearities into account and guarantees a constant safety-zone between failure load and working load. These proposal permits an economic design of timber/concrete composite beams. [source] Structural fire design according to Eurocode 5,design rules and their backgroundFIRE AND MATERIALS, Issue 3 2005Jürgen KönigArticle first published online: 18 NOV 200 Abstract This paper gives a review of the design rules of EN 1995-1-2, the future common code of practice for the fire design of timber structures in the Member States of the EU and EFTA, and makes reference to relevant research background. Compared with the European pre-standard ENV 1995-1-2, the new EN 1995-1-2 has undergone considerable changes. Charring is dealt with in a more systematic way and different stages of protection and charring rates are applied. For the determination of cross-sectional strength and stiffness properties, two alternative rules are given, either by implicitly taking into account their reduction due to elevated temperature by reducing the residual cross-section by a zero-strength zone, or by calculating modification factors for strength and stiffness parameters. Design rules for charring and modification factors are also given for timber frame members of wall and floor assemblies with cavities filled with insulation. A modified components additive method has been included for the verification of the separating function. The design rules for connections have been systemized by introducing simple relationships between the load-bearing capacity (mechanical resistance) and time. The code provides for advanced calculation methods for thermal and structural analysis by giving thermal and thermo-mechanical properties for FE analyses. The code also gives some limited design rules for natural fire scenarios using parametric fire curves. Copyright © 2004 John Wiley & Sons, Ltd. [source] Design of Plasmonic Thin-Film Solar Cells with Broadband Absorption EnhancementsADVANCED MATERIALS, Issue 34 2009Ragip A. Pala Noble metal nanostructures can enhance absorption in thin-film solar cells by simultaneously taking advantage of i) high near-fields surrounding the nanostructures close to their surface plasmon resonance frequency and ii) coupling to waveguide modes. We develop basic design rules for the realization of broadband absorption enhancements for such structures. [source] Channel estimation and physical layer adaptation techniques for satellite networks exploiting adaptive coding and modulationINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2008Stefano Cioni Abstract The exploitation of adaptive coding and modulation techniques for broadband multi-beam satellite communication networks operating at Ka-band and above has been shown to theoretically provide large system capacity gains. In this paper, the problem of how to accurately estimate the time-variant channel and how to adapt the physical layer taking into account the effects of estimator errors and (large) satellite propagation delays is analyzed, and practical solutions for both the forward and the reverse link are proposed. A novel pragmatic solution to the reverse link physical layer channel estimation in the presence of time-variant bursty interference has been devised. Physical layer adaptation algorithms jointly with design rules for hysteresis thresholds have been analytically derived. The imperfect physical layer channel estimation impact on the overall system capacity has been finally derived by means of an original semi-analytical approach. Through comprehensive system simulations for a realistic system study case, it is showed that the devised adaptation algorithms are able to successfully track critical Ka-band fading time series with a limited impact on the system capacity while satisfying the link outage probability requirement. Copyright © 2008 John Wiley & Sons, Ltd. [source] If bone is the answer, then what is the question?JOURNAL OF ANATOMY, Issue 2 2000R. HUISKES In the 19th century, several scientists attempted to relate bone trabecular morphology to its mechanical, load-bearing function. It was suggested that bone architecture was an answer to requirements of optimal stress transfer, pairing maximal strength to minimal weight, according to particular mathematical design rules. Using contemporary methods of analysis, stress transfer in bones was studied and compared with anatomical specimens, from which it was hypothesised that trabecular architecture is associated with stress trajectories. Others focused on the biological processes by which trabecular architectures are formed and on the question of how bone could maintain the relationship between external load and architecture in a variable functional environment. Wilhelm Roux introduced the principle of functional adaptation as a self-organising process based in the tissues. Julius Wolff, anatomist and orthopaedic surgeon, entwined these 3 issues in his book The Law of Bone Remodeling (translation), which set the stage for biomechanical research goals in our day. ,Wolff's Law' is a question rather than a law, asking for the requirements of structural optimisation. In this article, based on finite element analysis (FEA) results of stress transfer in bones, it is argued that it was the wrong question, putting us on the wrong foot. The maximal strength/minimal weight principle does not provide a rationale for architectural formation or adaptation; the similarity between trabecular orientation and stress trajectories is circumstantial, not causal. Based on computer simulations of bone remodelling as a regulatory process, governed by mechanical usage and orchestrated by osteocyte mechanosensitivity, it is shown that Roux's paradigm, conversely, is a realistic proposition. Put in a quantitative regulatory context, it can predict both trabecular formation and adaptation. Hence, trabecular architecture is not an answer to Wolff's question, in the sense of this article's title. There are no mathematical optimisation rules for bone architecture; there is just a biological regulatory process, producing a structure adapted to mechanical demands by the nature of its characteristics, adequate for evolutionary endurance. It is predicted that computer simulation of this process can help us to unravel its secrets. [source] Anwendung von Trapezblechstegen im BrückenbauBETON- UND STAHLBETONBAU, Issue 9 2009Längsschubtragverhalten von Betondübeln in Kombination mit Trapezblechstegen Brückenbau; Entwurf und Konstruktion Abstract Trapezblechstege im Brückenbau kommen trotz der großen Vorteile, die diese Bauweise bietet, in Deutschland bisher nur an einem Pilotprojekt zur Anwendung. Durch die charakteristischen Eigenschaften des Trapezbleches entstehen konstruktive und wirtschaftliche Vorteile gegenüber herkömmlichen Brückenbauweisen. Allerdings lassen die aktuell gültigen Regelwerke aufgrund fehlender Kenntnis zum Tragverhalten und mangelnder Erfahrung keine wirtschaftliche Ausbildung zu. Dies zeigt sich am Beispiel des Pilotprojekts. Die Ausbildung der Verbundfuge wurde hier nur sehr unbefriedigend gelöst und verdeutlicht somit die Notwendigkeit einfacher und praktikabler Verbindungsmöglichkeiten. Am Institut für Leichtbau Entwerfen und Konstruieren der Universität Stuttgart wurde in Zusammenarbeit mit dem Institut für Konstruktion und Entwurf ein von der Forschungsvereinigung für Stahlanwendung e. V. (FOSTA) finanziertes Forschungsvorhaben bearbeitet, bei dem unterschiedliche Verbundfugenausbildungen numerisch und experimentell untersucht wurden. Der folgende Beitrag beschränkt sich auf die Verwendung von Betondübeln als Verbundmittel und stellt hierfür ein einfaches Bemessungskonzept für die Verbundsicherung unter Längsschubbeanspruchung im Grenzzustand der Tragfähigkeit vor. The use of corrugated steel webs in bridge constructions , Load bearing behaviour of concrete dowels in combination with corrugated steel webs under longitudinal shear Studies of the load bearing behaviour under shear force of integrated connections at composite bridge girders using corrugated steel webs. Up to now there is only one project in Germany, where the application of corrugated steel webs has been practiced in the field of composite bridges. Due to the characteristics of the corrugated steel web this construction method has constructive and economic advantages. However there is a lack of experiences and standards to fully utilize these advantages and to allow an economic application. Especially the first project in Germany expose some critical points. The design of the joint between the concrete slab and the corrugated steel web is actually not satisfactory and shows the need for simpler and more practicable connection methods. At the Institute for Lightweight Structures and Conceptual Design at Universität Stuttgart and together with the Institute of Structural Design, a research project, financed by Forschungsvereinigung für Stahlanwendung e. V. (FOSTA) was made. Within this project different types of composite joints were experimentally and numerically analysed. This paper deals only with the investigations of concrete dowels as connectors. On the basis of these studies simple design rules for shear connection in the ultimate limit state were developed. [source] Durchstanzversuche mit Bewehrung mit hochfestem Verbund, innovative Traganalysen und BemessungsansätzeBETON- UND STAHLBETONBAU, Issue 8 2007Richard Rojek Prof. Dr.-Ing. Im vorliegenden Aufsatz wird über Durchstanzversuche berichtet, bei denen in die Stahlbeton-Versuchsplatten als Durchstanzsicherung Bewehrung mit hochfestem Verbund eingebaut wurde. Die Versuchsergebnisse zeigen, dass mit diesem System sehr gute Tragfähigkeiten erreicht werden. Aus den Rissbildern der nach den Versuchen aufgeschnittenen Versuchsplatten konnten interessante Rückschlüsse auf die Tragwirkung des Systems gezogen werden. Ein Vergleich dieser Rissbilder mit denjenigen von Versuchsplatten mit Doppelkopfankern als Durchstanzsicherung zeigt im Detail deutliche Unterschiede im Tragverhalten. Die Analyse der Versuchsergebnisse führt außerdem zu neuartigen Erkenntnissen über die Tragmechanismen im durchstanzgefährdeten Auflagerbereich von Stahlbetonplatten, die auch die Grundlage für einen Vorschlag bieten, die bestehenden Bemessungsregeln zu modifizieren. Slab Punching Tests with Reinforcement with High-Strength Bond In this paper there is given an account of punching tests, in which the tested concrete slabs were reinforced against punching by reinforcement with high-strength bond. The test results show that very good load capacities are obtainable. The pictures of the cracks, which were to be seen after the test slabs were cut up, gave interesting conclusions about the carrying behaviour of the system. Comparing these cracks with those of test slabs with double headed punching anchors clearly shows the differences of the carrying behaviours. The analysis of the test results also gives new knowledge about the carrying mechanisms at the critical punching zone of reinforced concrete slabs, which also build a basis for a proposal how to modify the existing design rules. [source] Kurze Verankerungslängen mit RechteckankernBETON- UND STAHLBETONBAU, Issue 1 2004Josef Hegger Prof. Dr.-Ing. Abstract In der Zulassung Z-15.6-204 [1] des Deutschen Instituts für Bautechnik werden Halfen HDB-E-Anker mit rechteckigen Köpfen als Endverankerung in Rahmenknoten und Konsolen für die Anwendung gemäß DIN 1045-1 und DIN 1045 geregelt. Durch die schlupfarme Verankerung der Zuggurtbewehrung ergeben sich Vorteile hinsichtlich der konstruktiven Durchbildung, der Tragfähigkeit und der Bauausführung. In diesem Beitrag werden die Zulassungsregelungen erläutert. Rectangular Anchors with short Anchorage Length The technical approval Z-15.6-204 [1] of the Deutsches Institut für Bautechnik gives design rules for the use of Halfen HDB-E-headed studs in exterior-beam-column-joints and corbels. The anchorage with headed studs is characterized by a negligible slippage of the reinforcement and is advantageous regarding the load bearing capacity, the detailing and the handling on site. This paper describes the design rules, devided from comprehensive experimental and numerical investigations [2]. [source] | |||||||||||||||||||||||||