			Home About us Contact

Design Requirements (design + requirement)

Distribution by Scientific Domains

Engineering	33%

Selected Abstracts

Compositionally Graded Steels: A Strategy for Materials Development,

ADVANCED ENGINEERING MATERIALS, Issue 12 2009
Béchir Chéhab
A topic of increasing importance in Materials Science is the optimization of microstructures to attain specific combinations of properties. Especially interesting are the design requirements where conflicting properties have to be simultaneously fulfilled. Compositionally graded and architectured materials, in which the properties change over space provide a means of meeting these challenging design requirements. [source]

Big diameter tunnelling beneath low rock cover.

GEOMECHANICS AND TUNNELLING, Issue 3 2009
Bau eines Großtunnels unter geringer Felsüberdeckung
Abstract The Clem Jones Tunnel (former North-South Bypass Tunnel) is the first project to get underway as part of Brisbane's transport plan which aims to improve the urban road network. The total length to be excavated is 6.8 km which includes 4.8 km of driven tunnel and associated road connections. Construction commenced in August 2006 with project completion targeted well before the contractual completion date of October 2010. Due to the local geology, in particular the hard Brisbane tuff and Neranleigh-Fernvale formation a combination of tunnel excavation methods are used. The majority of the tunnel is excavated by two tunnel boring machines in rock having a compressive strength of between 80 and 150 MPa. Ten roadheaders are excavating the remaining tunnels such as ramps, access tunnels, cross passages and merges. A major challenge arose during the planning of the initial mainline excavation underneath the Royal National Association Showground in Bowen Hills. This section contains low rock cover and historical maps indicate that the Showground is located within a former topographic depression (alluvial valley) where a creek once flowed through. Due to traffic merge design requirements, both TBM and roadheader excavation methods were required to be used in this challenging geological profile. The answer was to stabilise the alluvium above both TBM section tunnels from the surface prior to excavation and to operate the TBM in single shield mode with immediate grouting of annular void from the tail shield. In addition, the roadheader section of tunnel required additional support by spiles and canopy tubes installed from the tunnel face. Der Clem Jones Tunnel (ehemals North South Bypass Tunnel) ist das erste in Angriff genommene Projekt des Brisbane-Transportplans. Dieser Plan hat das Ziel, das städtische Straßennetzwerk zu verbessern. Insgesamt wird eine Strecke von 6,8 km aufgefahren, einschließlich 4,8 km bergmännische Tunnel und zugehörige Straßenanbindungen. Die Bauarbeiten begannen im August 2006, und die Fertigstellung des Projekts ist deutlich vor dem vertraglich vereinbarten Fertigstellungstermin im Oktober 2010 geplant. Der größte Teil der Tunnel wird durch zwei Tunnelbohrmaschinen im Hartgestein mit einer Druckfestigkeit zwischen 80 und 150 MPa ausgebrochen. Zehn Teilschnittmaschinen fahren die übrigen Tunnel wie Rampen, Zugangstunnel, Querschläge und Verbindungen auf. Eine große Herausforderung ergab sich während der Planung des Haupttunnelvortriebs unter dem Ausstellungsgelände der Royal National Association in Bowen Hills. Dieses Gebiet besitzt eine geringe Felsüberdeckung, und aus historischen Karten weiß man, dass das Ausstellungsgelände in einer ehemaligen topografischen Senke (alluviales Tal) liegt, durch die früher ein Bach floss. Aufgrund von Verkehrsplanungsanforderungen war es notwendig, sowohl Tunnelbohrmaschinen als auch Teilschnittmaschinen in dieser schwierigen geologischen Situation zu verwenden. Die Lösung bestand darin, das Schwemmland über beiden TBMTunneln von oben her zu stabilisieren und die Tunnelbohrmaschine in der Einfachschildbetriebsart zu fahren, wobei der Ringspalt vom Schildschwanz aus verpresst wird. Die durch Teilschnittmaschinen ausgebrochenen Tunnel mussten außerdem zusätzlich durch Spieße und eine Rohrschirmsicherung gestützt werden. [source]

Empirical design of computer support and staffing in concurrent engineering

HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 2 2006
Joe W. Meredith
Manufacturing environments are characterized by underlying operational approaches and assumptions. One such assumption is that concurrent engineering (CE) is superior to traditional sequential processing. A laboratory experiment was conducted using 180 engineering and building construction students as subjects. The engineering methodology variable was sequential and concurrent engineering. There were large teams, consisting of six students, and small teams, consisting of three students. The computer support variable was using and not using groupware. Each team was given a set of requirements to design a transportation system that moved a payload from one point to another. Each team was asked to (a) develop a design concept, (b) develop a detail design in the form of engineering drawings, (c) manufacture the system based on their design products (e.g., drawings and specifications) using toy plastic LEGOS, and (d) test the system to determine if it met the design requirements. There was no significant difference in performance between concurrent engineering groups and sequential engineering processes. Small groups significantly outperformed large groups in all conditions. Computer support did not significantly improve the performance of large or small groups. Participants in the experiment were equally satisfied with all conditions. An external survey strongly endorsed the superiority of CE as compared to sequential engineering. Results are discussed in terms of why practitioners believe in the effectiveness of CE, yet an empirical test failed to demonstrate better performance. © 2006 Wiley Periodicals, Inc. Hum Factors Man 16: 177,193, 2006. [source]

Determining the importance weights for the design requirements in the house of quality using the fuzzy analytic network approach

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 5 2004
Gülçin Büyüközkan
Quality function deployment (QFD) has been used to translate customer needs (CNs) and wants into technical design requirements (DRs) in order to increase customer satisfaction. QFD uses the house of quality (HOQ), which is a matrix providing a conceptual map for the design process, as a construct for understanding CNs and establishing priorities of DRs to satisfy them. This article uses the analytic network process (ANP), the general form of the analytic hierarchy process (AHP), to prioritize DRs by taking into account the degree of the interdependence between the CNs and DRs and the inner dependence among them. In addition, because human judgment on the importance of requirements is always imprecise and vague, this work concentrates on a fuzzy ANP approach in which triangular fuzzy numbers are used to improve the quality of the responsiveness to CNs and DRs. A numerical example is presented to show the proposed methodology. © 2004 Wiley Periodicals, Inc. [source]

Designing man-portable power generation systems for varying power demand

AICHE JOURNAL, Issue 5 2008
Mehmet Yunt
Abstract Portable electronic devices operate at varying power demand levels. This variability of power demand must be considered explicitly in the design of man-portable power generation systems for acceptable performance and portability. In this regard, a mathematical programming based design method is proposed. The method transcribes optimal operation of the system at a given power demand into a mathematical program. The power demand specific programs are incorporated into another upper level mathematical program encoding design requirements to form a final two-stage formulation. The design and operational parameters of the power generation system comprise a solution of the formulation. Unlike designs, based on a nominal power demand, the design guarantees that each power demand and all operational requirements can be satisfied. A detailed study of a microfabricated fuel-cell based system is performed. The proposed method produces smaller designs with significantly better performances than nominal power demand based approaches. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source]

The European standard for sun-protective clothing: EN 13758

JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 2 2006
T Gambichler
Abstract Clothing is considered one of the most important tools for sun protection. Contrary to popular opinion, however, some summer fabrics provide insufficient ultraviolet (UV) protection. The European Committee for Standardization (CEN), has developed a new standard on requirements for test methods and labelling of sun-protective garments. This document has now been completed and is published. Within CEN, a working group, CEN/TC 248 WG14 ,UV protective clothing', was set up with the mission to produce standards on the UV-protective properties of textile materials. This working group started its activities in 1998 and included 30 experts (dermatologists, physicists, textile technologists, fabric manufacturers and retailers of apparel textiles) from 11 European member states. Within this working group, all medical, ethical, technical and economical aspects of standardization of UV-protective clothing were discussed on the basis of the expertise of each member and in consideration of the relevant literature in this field. Decisions were made in consensus. The first part of the standard (EN 13758-1) deals with all details of test methods (e.g. spectrophotometric measurements) for textile materials and part 2 (EN 13758-2) covers classification and marking of apparel textiles. UV-protective cloths for which compliance with this standard is claimed must fulfill all stringent instructions of testing, classification and marking, including a UV protection factor (UPF) larger than 40 (UPF 40+), average UVA transmission lower than 5%, and design requirements as specified in part 2 of the standard. A pictogram, which is marked with the number of the standard EN 13758-2 and the UPF of 40+, shall be attached to the garment if it is in compliance with the standard. The dermatology community should take cognizance of this new standard document. Garment manufacturers and retailers may now follow these official guidelines for testing and labelling of UV-protective summer clothes, and the sun-aware consumer can easily recognize garments that definitely provide sufficient UV protection. [source]

Wandsysteme aus Fertigteilen für große Höhen

BETON- UND STAHLBETONBAU, Issue 10 2009
Martin Empelmann Prof. Dr.-Ing.
Berechnungs- und Bemessungsverfahren; Entwurf und Konstruktion Abstract Bei Hallenbauten werden die Außen- oder Innenwände oft aus zwischen den Stützen übereinander angeordneten Wandelementen aus Stahlbeton-Fertigteilen erstellt. Je nach den individuellen bautechnischen Anforderungen kann auf dem obersten Wandelement noch ein weiterer Wandaufbau aus leichten Porenbetonplatten erfolgen. Die Befestigung derartiger Wandelemente an den seitlich angeordneten Stützen oder anderen Bauteilen erfolgt entweder punktförmig, beispielsweise durch Dollen, oder kontinuierlich, z. B. durch Seilschlaufen. Zusätzlich können diese Wände, bei entsprechender Ausbildung auch als aussteifende Wandscheiben zur Aussteifung des Gesamtsystems oder als Brandwände genutzt werden. Bei der Detailausführung und dem Stabilitätsnachweis derartiger Wandscheiben sind einige Besonderheiten zu beachten, auf die in diesem Aufsatz eingegangen werden soll. Wall Systems for Exceptional Heights For industrial hall constructions, the outside and/or inside walls are very often constructed as precast panel wall systems, with single concrete wall panels mounted on top of each other. According to the design requirements the top panel can be loaded by the weight of a further wall system, very often consisting of lighter aereated concrete panels. The wall panels are normally fixed either at defined points by dowels or continuously, e.g. by a wire rope loop system. Furthermore, these wall systems, if appropriately constructed, can be used as stiffening members for the overall construction or as fire walls. For the detailing, dimensioning and stability analysis of these wall panels some special features have to be observed, which will be pointed out in this paper. [source]