Design Guidelines (design + guideline)

Distribution by Scientific Domains
Distribution within Engineering

Selected Abstracts

Social enrichment by virtual characters , differential benefits

A. Gulz
Abstract It is frequently held forth, within the area of virtual pedagogical characters, that such characters are beneficial for learning as they strengthen the social dimension of electronic learning environments. This article presents more details on this proposal together with a survey of corresponding empirical evidence. In addition, materials from a recently conducted empirical study are presented. Ninety school children, 12,15-year-old, were asked (i) to grade the idea of virtual characters in electronic learning environments and (ii) to chose between a strictly task-oriented, socially ,shallow' and a more socially oriented pedagogical character. The participants were also asked to articulate the reasons behind their answers, and to share their thoughts and opinions on the issues. The results of the study, as well as of several of the studies reviewed, indicate that responses and attitudes towards social aspects of virtual pedagogical characters are highly divergent. In particular, the notion that social dimensions of virtual characters increase learners' motivation and engagement may be less generally applicable in a student population than is sometimes hypothesized. An ensuing design guideline suggests interface solutions with an emphasis on flexibility regarding social orientation and communicative style in virtual characters. [source]

On the accuracy of simplified methods for the analysis of isolated bridges

P. Franchin
Abstract To foster the use of seismic isolation in structures, existing guidelines strive to formulate design methods which are simple and accessible to non-specialized engineers. On the other hand, not all of the simplifying provisions adopted by the norms can be said to have been adequately tested to provide a consistent level of accuracy. The study attempts, in particular, to elucidate three aspects related to the methods of analysis for linear or linearized isolated bridges on which little or no advice can be found in the norms. The first one is about the way one has to account for the fact that damping matrices of isolated bridges are never of proportional type. The present study demonstrates, through a number of typical applications, that classical modal analysis, using real modes and the diagonal terms of the modal damping matrices, still provide a fully acceptable approximation. The second and third aspects are related to the use of linearization expressions extended to the analysis of hyperstatic bridges. Parametric analyses conducted in the study show that none of the formulas in current use gives satisfactory results for both the displacement and the force responses, a requirement for a reliable design of an isolated bridge. How to use the equivalent linear parameters, and in particular the isolators equivalent damping ratios, in the context of a modal analysis, is treated next. This problem is seldom if ever mentioned in the norms where at most a formula is given for constructing modal damping ratios based on the damping ratios of the isolators. A rational, approximate procedure is discussed in this paper, applicable to all types of structures with non-proportional damping, which in the case of bridges can be shown to reduce to the expression provided in the Japanese bridge design guidelines. Copyright 2001 John Wiley & Sons, Ltd. [source]

That site looks 88.46% familiar: quantifying similarity of Web page design

EXPERT SYSTEMS, Issue 3 2005
Giselle Martine
Abstract: Web page design guidelines produce a pressure towards uniformity; excessive uniformity lays a Web page designer open to accusations of plagiarism. In the past, assessment of similarity between visual products such as Web pages has involved an uncomfortably high degree of subjectivity. This paper describes a method for measuring perceived similarity of visual products which avoids previous problems with subjectivity, and which makes it possible to pool results from respondents without the need for intermediate coding. This method is based on co-occurrence matrices derived from card sorts. It can also be applied to other areas of software development, such as systems analysis and market research. [source]

Design, analysis, and synthesis of generalized single step single solve and optimal algorithms for structural dynamics

X. Zhou
Abstract The primary objectives of the present exposition are to: (i) provide a generalized unified mathematical framework and setting leading to the unique design of computational algorithms for structural dynamic problems encompassing the broad scope of linear multi-step (LMS) methods and within the limitation of the Dahlquist barrier theorem (Reference [3], G. Dahlquist, BIT 1963; 3: 27), and also leading to new designs of numerically dissipative methods with optimal algorithmic attributes that cannot be obtained employing existing frameworks in the literature, (ii) provide a meaningful characterization of various numerical dissipative/non-dissipative time integration algorithms both new and existing in the literature based on the overshoot behavior of algorithms leading to the notion of algorithms by design, (iii) provide design guidelines on selection of algorithms for structural dynamic analysis within the scope of LMS methods. For structural dynamics problems, first the so-called linear multi-step methods (LMS) are proven to be spectrally identical to a newly developed family of generalized single step single solve (GSSSS) algorithms. The design, synthesis and analysis of the unified framework of computational algorithms based on the overshooting behavior, and additional algorithmic properties such as second-order accuracy, and unconditional stability with numerical dissipative features yields three sub-classes of practical computational algorithms: (i) zero-order displacement and velocity overshoot (U0-V0) algorithms; (ii) zero-order displacement and first-order velocity overshoot (U0-V1) algorithms; and (iii) first-order displacement and zero-order velocity overshoot (U1-V0) algorithms (the remainder involving high-orders of overshooting behavior are not considered to be competitive from practical considerations). Within each sub-class of algorithms, further distinction is made between the design leading to optimal numerical dissipative and dispersive algorithms, the continuous acceleration algorithms and the discontinuous acceleration algorithms that are subsets, and correspond to the designed placement of the spurious root at the low-frequency limit or the high-frequency limit, respectively. The conclusion and design guidelines demonstrating that the U0-V1 algorithms are only suitable for given initial velocity problems, the U1-V0 algorithms are only suitable for given initial displacement problems, and the U0-V0 algorithms are ideal for either or both cases of given initial displacement and initial velocity problems are finally drawn. For the first time, the design leading to optimal algorithms in the context of a generalized single step single solve framework and within the limitation of the Dahlquist barrier that maintains second-order accuracy and unconditional stability with/without numerically dissipative features is described for structural dynamics computations; thereby, providing closure to the class of LMS methods. Copyright 2003 John Wiley & Sons, Ltd. [source]

Analytical comparison of reversed nested Miller frequency compensation techniques

Alfio Dario Grasso
Abstract In this paper, novel and previously proposed reversed nested Miller compensation (RNMC) networks are analyzed and compared, and their design equations are also presented. Hence, this paper is the natural extension of a previous paper by the authors (Int. J. Circ. Theor. Appl. 2008; 36(1):53,80), where only the nested Miller compensation topologies were treated. In particular, a coherent and comprehensive analytical comparison of the RNMC topologies, including two new networks presented for the first time, is performed by means of the figure of merit that expresses a trade-off among gain-bandwidth product, load capacitance and total transconductance, for equal values of phase margin (Int. J. Circ. Theor. Appl. 2008; 36(1):53,80). The analysis shows that there is no unique optimal solution among the RNMC topologies, as this depends on the load condition as well as on the relative transconductance magnitude of each amplifier stage. From this point of view, the proposed comparison also outlines useful design guidelines for the optimization of large-signal and small-signal performance. Simulations confirming the effectiveness of the proposed design methodology and analytical comparison are also included. Copyright 2009 John Wiley & Sons, Ltd. [source]

Congestion control for multimedia applications in the wireless internet

Veselin Rakocevic
Abstract This paper provides a parallel review of two important issues for the next-generation multimedia networking. Firstly, the emerging multimedia applications require a fresh approach to congestion control in the Internet. Currently, congestion control is performed by TCP; it is optimised for data traffic flows, which are inherently elastic. Audio and video traffic do not find the sudden rate fluctuations imposed by the TCP multiplicative-decrease control algorithm optimal. The second important issue is the mobility support for multimedia applications. Wireless networks are characterized by a substantial packet loss due to the imperfection of the radio medium. This increased packet loss disturbs the foundation of TCP's loss-based congestion control. This paper contributes to the ongoing discussion about the Internet congestion control by providing a parallel analysis of these two issues. The paper describes the main challenges, design guidelines, and existing proposals for the Internet congestion control, optimised for the multimedia traffic in the wireless network environment. Copyright 2004 John Wiley & Sons, Ltd. [source]

On the transmission properties of left-handed microstrip lines implemented by complementary split rings resonators

M. Gil
Abstract In this paper, the transmission properties of left-handed microstrip lines implemented by etching complementary split rings resonators (CSRRs) and capacitive gaps in the ground plane and conductor strip, respectively, are investigated. To this end, we make use of the lumped element equivalent circuit model of the structure, from which an accurate analysis is carried out, and the influence of the main electrical parameters on the transmission properties is pointed out through electrical simulations. Aspects such as bandwidth and in-band ripple control are discussed in detail. The influence of the geometrical parameters is also discussed and interpreted to the light of the equivalent circuit model. From the results obtained, there are inferred design guidelines that are suitable for the design of metamaterial transmission lines subjected to specifications. Copyright 2006 John Wiley & Sons, Ltd. [source]

Designing ubiquitous computing to enhance children's learning in museums

T. Hall
Abstract In recent years, novel paradigms of computing have emerged, which enable computational power to be embedded in artefacts and in environments in novel ways. These developments may create new possibilities for using computing to enhance learning. This paper presents the results of a design process that set out to explore interactive techniques, which utilized ubiquitous computer technology, to stimulate active participation, involvement and learning by children visiting a museum. Key stakeholders, such as museum curators and docents, were involved throughout the process of creating the exhibition, Re-Tracing the Past, in the Hunt Museum, Limerick, Ireland. The paper describes aspects of the evaluation of the exhibition, which involved 326 schoolchildren (ages 9,12-year-old), and which exemplifies important features of the design and use of the novel technology in the museum. The paper concludes by articulating a series of design guidelines for developing ubiquitous computing to enhance children's learning in museums. These guidelines relate 12 experiential criteria to five supporting design informants and resources. The guidelines encompass important dimensions of children's educational experience in museums, including collaboration, engagement, active interpretation, and materiality. While developed in a museum context, these guidelines could be applied to the development of novel computing to enhance children's learning in other educational environments, both formal and informal. [source]

Geometric design of fluid segments in microreactors using dimensionless numbers

AICHE JOURNAL, Issue 4 2006
Nobuaki Aoki
Abstract In microreactors, reactant fluids are split into many fluid segments and then fed into the reactors to shorten mixing time. Two dimensionless numbers are introduced to represent effects of geometric design factors of fluid segments, such as shapes and arrangements, on reactor performance, namely mixing rate and product yield and selectivity: the ratio of reaction rate to diffusion rate and the aspect ratio of the mean diffusion length in the two-dimensional (2-D) directions in the reactor cross section. Methods to determine these numbers are also proposed. To examine the validity of these numbers on estimating the reactor performance, we compare product yields between each pair of reactors having the different geometric design factors but the same dimensionless numbers using computational fluid dynamics simulations. The results show that these numbers serve as the indices for estimating the reactor performance. Using these numbers, design guidelines for geometry of fluid segments are also discussed. 2005 American Institute of Chemical Engineers AIChE J, 2006 [source]

The effect of retainer thickness on posterior resin-banded prostheses: a finite element study

T.-S. Lin
summary, According to its design concept, a resin-bonded prosthesis, compared with the conventional fixed partial denture, is a weak and unstable structure. Therefore, a resin-bonded prosthesis induces a higher failure rate, especially in the posterior region. Recently, adhesion agents have been profoundly improved. However, the design guidelines of posterior resin-bonded prostheses (RBP) have seldom been evaluated from a biomechanical perspective. The objective of this study was to investigate the biomechanical effects of the retainer thickness on posterior RBP using the finite element method. A solid model of a posterior mandibular resin-bonded prosthesis, which employed the second molar and second premolar as the abutment teeth, was constructed and meshed with various retainer thickness (ranging from 02 to 10 mm). Horizontal and vertical loadings of 200 N were applied respectively at the central fossa of the pontic to examine the stress level at the interface between the retainer and abutment teeth. All exterior nodes in the root, below the cementoenamel junction were fixed as the boundary condition. The results showed that horizontal loading would induce higher interfacial stresses than the vertical loading which indicated that the horizontal component of the occlusal force plays a more important role in evaluating the debonding phenomenon. Further, the peak interfacial stresses increased as the retainer thickness decreased and, based on the fitted relation between retainer thickness and interfacial stresses, a 04 mm retainer thickness was suggested as the minimum required to prevent severe interfacial stresses increasing. [source]

Controlled user evaluations of information visualization interfaces for text retrieval: Literature review and meta-analysis

Charles-Antoine Julien
This review describes experimental designs (users, search tasks, measures, etc.) used by 31 controlled user studies of information visualization (IV) tools for textual information retrieval (IR) and a meta-analysis of the reported statistical effects. Comparable experimental designs allow research designers to compare their results with other reports, and support the development of experimentally verified design guidelines concerning which IV techniques are better suited to which types of IR tasks. The studies generally use a within-subject design with 15 or more undergraduate students performing browsing to known-item tasks on sets of at least 1,000 full-text articles or Web pages on topics of general interest/news. Results of the meta-analysis (N = 8) showed no significant effects of the IV tool as compared with a text-only equivalent, but the set shows great variability suggesting an inadequate basis of comparison. Experimental design recommendations are provided which would support comparison of existing IV tools for IR usability testing. [source]

High gain cavity-backed slot antenna with a windowed metallic superstrate

M. A. Hanqing
Abstract A novel technique for gain enhancement of cavity-backed slot antenna is developed and discussed. The high gain radiation of the proposed antenna is achieved by a windowed metallic superstrate above the slot. The parametric studies of the proposed structure are provided, the radiation mechanism of the proposed antenna is investigated, and then the design guidelines for this type of radiators are described. The prototype is fabricated and found to have an impedance bandwidth of 12% and a gain of 12.3 dBi at the center frequency of 2.4 GHz. The characteristics of the proposed antenna have been validated by CST simulation software and experiments. 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3114,3118, 2008; Published online in Wiley InterScience ( DOI 10.1002/mop.23880 [source]

Ultrawideband aperture-coupled vertical microstrip transition

A. M. Abbosh
Abstract Simple design guidelines for an ultrawideband aperture-coupled vertical microstrip,microstrip transition are presented. The proposed transition utilizes broadside coupling between elliptical-shaped microstrip patches at the top and bottom layers via an elliptical-shaped slot in the ground plane, which is located at the mid layer. The simulated and measured results show that the proposed transition has less than 0.75 dB insertion loss and more than 13 dB return loss across the frequency band 3.1,10.6 GHz. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2207,2209, 2007; Published online in Wiley InterScience ( DOI 10.1002/mop.22667 [source]

Design of a UWB planar 180 hybrid exploiting microstrip-slot transitions

A. M. Abbosh
Abstract The article describes the design of a planar 180 hybrid with an ultra wideband (UWB) performance. The device employs two substrates with a common ground plane and various microstrip-slot transitions to achieve in-phase and out-of-phase signal division over an ultra wide frequency range. At the initial stage, simple design guidelines are used but the final dimensions are determined using a full-wave analysis and design software package. The simulated and measured results of the proposed device reveal a well balanced power split accompanied by a very good approximation of ideal 180 and 0 differential phase shift across the band 3.1 to more than 11 GHz. Also low insertion losses, good return loss at all of the four ports, high isolation between the input ports and fine isolation between output ports are noted across this frequency band. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1343,1346, 2007; Published online in Wiley InterScience ( DOI 10.1002/mop.22472 [source]

Coplanar to microstrip transitions for on-wafer measurements

Yi Wang
Abstract Two types of via-free coplanar line to microstrip transitions are designed and tested for on-wafer measurements. The transitions are designed to fit coplanar ground-signal-ground probes. They are taper transitions with capacitive ground patches and radial stub transitions. Both structures are easy implemented and exhibit wideband transmission. The performance of the optimized taper transition is among the best demonstrated in terms of a return loss of less than ,20 dB from 5 to 15.5 GHz; this is even superior to the radial stub designs. Design information is given, which is based on full-wave simulations for the taper transition, and analytical formulations for the radial stub. The increasing bandwidth with increased angle of the radial stub is observed. The transition structures and design guidelines addressed can be used for on-wafer measurements of a wide range of microstrip circuits. 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 100,103, 2007; Published online in Wiley InterScience ( DOI 10.1002/mop.22056 [source]

Web portal design guidelines as identified by children through the processes of design and evaluation

Andrew Large
The Web is an important source of information for school projects, but young users do not always find it easy to locate relevant material. A critical factor in success is the portal through which they search or browse web content. Traditionally web portals have been designed by adults with young users in mind, but there is very little evidence that the latter make use of them. In this paper design guidelines are elaborated for such portals that are based upon focus group and operational evaluations by elementary school students of two prototype web portals designed by two intergenerational teams, each comprising elementary school students and adult designers. The evaluations offer strong support for involving children throughout the design process for portals that both in presentation and functionality reflect the cognitive and affective needs of young users rather than adults. [source]

Automated Assessment of Early Concept Designs

Chuck Eastman
Abstract Building information modelling (BIM) is a powerful tool for clients and architects alike, particularly when clients have ongoing complex programmatic requirements. Chuck Eastman describes how with his team* at the AEC Integration Laboratory at the College of Architecture at the Georgia Institute of Technology he was commissioned by the US federal government's General Service Administration (GSA) to automate the design guidelines for all US courthouses in such a way that preliminary designs by architects could be assessed and checked against specific criteria. Copyright 2009 John Wiley & Sons, Ltd. [source]