Specific Design Cases Research Articles

Space Portrait: Establishment of a Lifestyle-Directed Visualized Model for Interior Design

Effective interior design service relies on users′ needs and the agreements between designers and users; this requires good communication between the two parties. Therefore, establishing an interactive model to record user involvement in the design process, as well as visually analyzing the user′s lifestyle and needs, warrants exploration. This study targeted specific interior design cases and the daily lives of users. The research introduces a sphere activity change map that uses information visualization to understand users′ daily activities. This model offers a life-model-based information tree as a tool to highlight the space spheres individual family members emphasize. The tool then visualizes the distribution of the average time family members spend in each space sphere.

Numerical analysis of canister movements in an engineered barrier system

The mid-term safety of deep geological nuclear waste repositories is based in part on the presence of a buffer, the main role of which is to isolate the environment from radionuclides. A design evaluation of such a repository is necessary to assess the potential vertical canister movement inside the drift that could reduce the buffer efficiency. A thermo-hydro-mechanical (THM) simulation is performed in a vertical cross-section of the drift. The THM couplings are described, and their influences on the mid-term (300 years) response of the engineered barrier system (EBS) are revealed. This study uses an advanced constitutive model to simulate the THM processes that occur in a specific EBS design case. The near-field simulations of the nuclear waste canister are performed in a two-dimensional finite element configuration that considers the effect of gravity. The focus of this study is on the mechanical behaviour of the buffer, which consists of two different forms of bentonite. Such an approach allows realistic consideration of the effect of the wetting and drying of the buffer material in non-isothermal conditions. Due to a specific design that includes bentonite blocks and pellets, the canister is observed to heave slightly during the re-saturation period, which extends up to 100 years.

The Impacts of Cathode Catalyst Layer Morphology on PEMFC Design

IntroductionCommercializing polymer electrolyte membrane fuel cells (PEMFC) is ultimately a matter of achieving the necessary cost for market penetration. Cost is a function of materials, manufacturability, performance, and durability. Performance and durability targets have been set by the DOE [1] to provide guidance and focus to the PEMFC industry for specific applications such as the automotive sector.Since both performance and durability are heavily dependent on operating conditions, PEMFC design will be strongly dependent upon the specific requirements of any given commercial application. Designing PEMFCs for applications with narrow operating windows (eg. low or high RH) is a relatively simple task; however, most commercial applications have performance/durability requirements that must be met across a wide range of operating conditions.Cathode catalyst layer morphology is one of the dominating factors for achieving the performance and durability required for many applications; therefore, understanding how manufacturing impacts the catalyst layer morphology and the resulting performance under a wide range of operating conditions is important for designing commercial PEMFCs. Results & Discussion Aside from catalyst activity the cathode catalyst layer performance is dictated completely by the mass transport of protons (proton conductivity), oxygen (gas diffusivity), and water (gas & liquid permeability) [2-4]. Figure 1 shows the balance between proton conductivity and catalyst layer porosity as a function of ionomer loading.Figure 1 – Maximum performance obtained at 30wt% ionomer content with a balance between proton conductivity and gas porosity.Understanding the processes and variables required to control these mass transport parameters is necessary for proper PEMFC design [5-6]. Table 1 outlines several processes and design variables that help control mass transport through the cathode catalyst layer and have therefore had an impact on both performance and durability.Table 1 – Design variables that affect key functions for PEMFC performance. A study was conducted investigating several of these variables, resulting in relationships with mass transport and ultimately performance.These relationships have been used to design a robust catalyst layer that is capable of performing under a wider range of operating conditions compared to previous designs. The goal of this specific design case was to achieve the best attributes of both the top performing MEA over a range of operating conditions and the most durable MEA, in a single design.Starting with a more corrosion resistant catalyst, the performance was increased under a wider range of operating conditions, by improving proton, oxygen, and water mass transport. This was successfully done by utilizing the relationships described above, specifically regarding the types of catalyst and ionomer, the catalyst-ionomer ratio, mixing and coating methodologies and layer contiguity. AcknowledgementThe authors would like to acknowledge National Resources Canada (NRCan), National Research Council of Canada (NRC-IRAP), and the US Department of Energy (DOE) for funding various aspects of this work. Reference1.http://www1.eere.energy.gov/hydrogenandfuelcells/mypp/pdfs/fuel_cells.pdf2. Egushi, M., Baba, K., Onuma, T., Yoshida, K., Iwasawa, K., Kobayashi, Y., Uno, K., Komatsu, K., Kobori, M., Nishitani-Gamo, M., Ando, T., Polymers, 4, p. 1645 (2012)3. Xie, J., Xu, F., Wood, D.L., More, K.L., Zawodzinski, T.A., Smith, W.H., Electrochimica Acta 55 p. 7404 (2010)4. Gode, P., Jaouen, F., Lindbergh, G., Lundblad, A., Sundholm, G., Electrochimica Acta 48 p. 4175 (2003)5. Mehta, V., Cooper, J.S., J. Power Sources 114, p. 32

Reusing design knowledge based on design cases and knowledge map

Design knowledge was reused for innovative design work to support designers with product design knowledge and help designers who lack rich experiences to improve their design capacity and efficiency. First, based on the ontological model of product design knowledge constructed by taxonomy, implicit and explicit knowledge was extracted from some design cases. The design knowledge was expressed using a constructional organization. With the knowledge map, design knowledge was illustrated to help novice designers reconstruct specific design cases, thus, encouraging innovative design. Four groups of designers were invited to participate in an experiment for the design knowledge map system. The experiment results verified the effectiveness of the method.

External perforated Solar Screens for daylighting in residential desert buildings: Identification of minimum perforation percentages

The desert climate is endowed by clear sky conditions, providing an excellent opportunity for optimum utilization of natural light in daylighting building indoor spaces. However, the sunny conditions of the desert skies, in countries like Egypt and Saudi Arabia, result in the admittance of direct solar radiation, which leads to thermal discomfort and the incidence of undesired glare. One type of shading systems that is used to permit daylight while controlling solar penetration is “Solar Screens”. Very little research work addressed different design aspects of external Solar Screens and their influence on daylighting performance, especially in desert conditions, although these screens proved their effectiveness in controlling solar radiation in traditional buildings throughout history.This paper reports on the outcomes of an investigation that studied the influence of perforation percentage of Solar Screens on daylighting performance in a typical residential living room of a building in a desert location. The objective was to identify minimum perforation percentage of screen openings that provides adequate illuminance levels in design-specific cases and all-year-round.Research work was divided into three stages. Stage one focused on the analysis of daylighting illuminance levels in specific dates and times, while the second stage was built on the results of the first stage, and addressed year round performance using Dynamic Daylight Performance Metrics (DDPMs). The third stage addressed the possibility of incidence of glare in specific cases where illuminance levels where found very high in some specific points during the analysis of first stage. The research examined the daylighting performance in an indoor space with a number of assumed fixed experimentation parameters that were chosen to represent the principal features of a typical residential living room located in a desert environment setting.Stage one experiments demonstrated that the screens fulfilled the requirements of the majority of tested cases. Illuminance levels in the examined residential space were satisfactory in 83% of the near zone cases and 53% in the mid-length zone, while the far zone suites 40% of the cases. Screen influence on daylighting was found to be very much dependent on the orientation of the window and time of the day.In stage two, the percentage of annual “Daylight Availability” was very much related to screen perforation percentage. As perforation percentage decreased, the percentage of Daylit and Over lit spaces decreased. At the same time, Partially Daylit areas of the space increased with similar percentages irrespective of the orientation. As a result of the twofold research stages, it is recommended to utilize a minimum of 80% perforation percentages for spaces similar to the tested case in the South orientation.In stage three, an initial investigation suggests that the use of screens can significantly reduce the occurrence of glare phenomena. Also, it is suggested to study the efficiency of designing Solar Screens that have non-uniform perforation ratios. These could prove useful in improving the illuminance levels in the mid-length and far zones of the unsatisfactory cases.In conclusion, minimum perforation percentages for Solar Screens were presented for specific design cases that encompassed different orientations, seasons and time of the day. In addition, a tool that could be used by architects for based on required annual “Daylit” areas for the design of Solar Screens that effectively achieve functional needs was provided.

Robust PECVD SiC membrane made for stencil lithography

Stencil lithography (SL) is a shadow mask technique which allows parallel, resistless, micro- and nano-patterning of material through apertures created in a membrane (stencil) onto a substrate. The stencils are usually made of LPCVD low-stress SiN due to its outstanding physical and chemical stability. However, limitations are found for some specific design cases, where membranes can be distorted because of the deformations induced by stress from the deposited materials. Here we present a recently developed PECVD SiC shadow mask for applications in SL. The SiC has higher Young’s modulus than SiN, which transfers to a better performance for SiC stencil than the shadow mask made of SiN in terms of robustness to the stress-induced deformation. We show direct local etching of SiO2 through SiC stencil, otherwise impossible with SiN masks. SiC stencils with both compressive and tensile stresses were fabricated and compared to the SiN stencils. The higher robustness to deformation and better resistance to etching of the SiC membranes allow for a wider choice of the deposited materials, leading themselves to a more precise pattern duplication and less complicated resistless dry etching applications.

Global synthesis of superdirective frequency‐invariant beam patterns

Frequency‐invariant beam patterns are often required by systems using an array of sensors to process broadband signals. If the spatial aperture is shorter than the involved wavelengths, the use of a superdirective beam pattern is essential to attain an efficient system. In this context, robustness to array imperfections is a crucial feature. In the literature, only a few approaches have been proposed to design a robust, superdirective, frequency‐invariant beamformer, based on a filter and sum architecture: in all of them, the frequency invariance is achieved imposing an a priori desired beam pattern. However the choice of a suitable desired beam pattern is not trivial and depends on the specific design case: an improper selection of the desired beam pattern can produce unsatisfactory performances. We propose a new method of global synthesis, computationally inexpensive, allowing to design a robust broadband beam pattern with an optimal trade‐off between the frequency invariance and the directivity, without the need of imposing a priori a desired beam pattern. The results show that the synthesized beam patterns have a directivity, a frequency‐invariance, and a robustness that are very similar to or better than those of the beam patterns obtained by the literature methods.

Application of microstructure sensitive design to structural components produced from hexagonal polycrystalline metals

In this paper, we present the first successful design case studies in the application of microstructure sensitive design (MSD) methodology to optimize performance of structural components made from polycrystalline metals with hexagonal close-packed (hcp) crystal lattices. It is demonstrated that the underlying spectral framework of the MSD methodology facilitates an efficient consideration of the complete set of crystallographic textures in the design optimization. In order to accomplish this task a number of important enhancements had to be introduced to the MSD framework. The most significant enhancement is in the mathematical description of the design space, i.e. the texture hull. The advantages of the new approach described in this paper are illustrated with two specific design case studies involving different assumptions of symmetry at the sample scale. In both case studies presented, it is seen that the overall performance is strongly influenced by the crystallographic texture in the sample. Furthermore, the relevant property closures and performance maps accounting for the complete set of textures are also depicted.

Finite Element Study of Stability of Corroded Metal Culverts

The development and the use of finite element analyses in the 1970s and 1980s changed the nature of culvert assessment because they permitted consideration of the geometrical and material details of the burial condition, as well as the construction process, culvert geometry, and earth and vehicle loads. While these procedures have been used to study a wide range of new culvert and pipe structures, there has been little consideration of the structural deterioration that is precipitating most current infrastructure investments. This study therefore examines the influence of corrosion on the stability of corrugated steel culverts. Corrosion in the lower half of the structure is considered, including a range of losses in wall thickness and lateral extents. Changes in the factor of safety against yield are assessed as corrosion develops, as are changes in culvert resistance to buckling failure. For the five specific design cases considered, the governing design criterion was stability against yield, and the factor of safety against yield was found to decrease almost in proportion to wall thickness (when maximum wall thrust within the corroded zone was considered). This decrease occurred because the corroded metal culverts experienced little change in the distributions of thrust or moment as a result of local losses in wall thickness. While the results presented are purely theoretical, they provide a starting point for an appreciation of the influence of metal culvert deterioration and can guide future research, including physical test programs.

AN LMI-BASED METHOD FOR H2/H∞ CONTROL DESIGN UNDER SPARSITY CONSTRAINTS

H2 and H∞ based control design methodologies are widely used to deal with multivariable control problems. In general, however, finding a norm-minimizing controller subject to a structural constraint is not a convex optimization problem, and in many cases is intractable. In this paper we propose an LMI based solution to some H2/H∞ specific design cases where the controller satisfies a quadratic invariance property with respect to the controlled system. The proposed method can be applied indifferently on stable or unstable systems. The problem of Lower Block Triangular (LBT) H2/H∞ controller design is considered as a particular case. Finally, an application to the control of a platoon of vehicles problem and a comparison with some existing methods is given.

The Importance of Waste Packaging Advice Following Rejection of the Nirex RCF Planning Application

The decision to reject the Nirex application to build the Rock Characterisation Facility at Longlands Farm in Cumbria will inevitably lead to a delay in the development of the UK deep repository for intermediate level waste. This delay, however, has not had a major impact on the Nirex approach to waste packaging as the strategy has always been to ensure that Waste Package Specifications are not specific to a particular site or design. In the absence of a finalised repository site, design or associated safety cases, Nirex has not been in a position to issue final Waste Acceptance Criteria. Nirex has instead produced and issued a suite of waste package specifications and guidance documentation which define packaging standards and which give guidance to customers on the form of packaging which will be consistent with developing plans for safe transport, handling, storage and disposal. The documentation is not based on a specific repository design or safety case, but is founded on design concepts and safety assessments for generic transport and underground repository systems. Many customers are now developing waste management strategies that involve the retrieval and packaging of waste in a form that will be suitable for interim storage and deep disposal. In such situations Nirex will assist customers by the provision of waste packaging advice, and if proposals are consistent with plans for transport, handling, storage and disposal, by the issue of a Letter of Comfort. Experience has shown that there is value in seeking Nirex advice at three stages in the development of a waste packaging project: at the conceptual stage, at the pre-commitment stage and finally prior to active commissioning. Nirex advice will enable agreements to be reached on key issues such as waste package design, wasteform and data recording. It will identify areas of uncertainty or where further evidence and/or R&D may be required and will ensure that satisfactory QA systems are in place prior to plant operations. Assuming that there are no outstanding issues, Nirex will issue a final Letter of Comfort. This process has been recognised as being of value by Nirex, regulators and customers. The Nirex strategy to define packaging standards against generic repository and transport system concepts has been shown to be robust and continues to provide an appropriate standard for waste packaging.

SPIDA: Abstracting and generalizing layout design cases

Abstraction and generalization of layout design cases generate new knowledge that is more widely applicable to use than specific design cases. The abstraction and generalization of design cases into hierarchical levels of abstractions provide the designer with the flexibility to apply any level of abstract and generalized knowledge for a new layout design problem. Existing case-based layout learning (CBLL) systems abstract and generalize cases into single levels of abstractions, but not into a hierarchy. In this paper, we propose a new approach, termed customized viewpoint—spatial (CV–S), which supports the generalization and abstraction of spatial layouts into hierarchies along with a supporting system, SPIDA (SPatial Intelligent Design Assistant).

CADSYN: A case-based design process model

In solving a new design problem, the case-based reasoning paradigm provides a process model where previous experience in the form of multiple, individual design situations can be used in a new design context. Design synthesis presents challenges to current methodologies of CBR in the application of the various approaches to case memory organization, indexing, selection and transformation. The focus of this paper is on the transformation process. Multiple types of design knowledge are essential to derive a new design solution. A hybrid case-based design process model, CADSYN, is proposed to integrate specific design situations and generalized domain knowledge, where specific cases are represented as attribute-value pairs and domain knowledge is represented by generalized design concepts and constraints. Case transformation is treated as a constraint satisfaction problem, where a specific design case provides a starting point for a new design problem and constraints are used to revise the case for consistency with the new context.

The incorporation of human aspects into a unified design theory

Research into design theory has, up until now, concentrated mostly upon the technical aspects of the process. Techniques have been developed that, on the one hand allow the general processes of design to be described in terms of a global system, whilst on the other, researchers have been addressing and attempting to automate specific detailed design cases through the application of knowledge based techniques applied to CAD/CAM systems. The design process should, however, be considered as a unified activity that incorporates human skill and organisational relationships as well as the available technology. All of these must be matched to the product goals of a given activity. The CAD research group at Brunel University has been creating a design modelling system based upon constraints. Here set theory techniques are used within a knowledge based system to resolve any conflicts between constraining rules. This process has been successfully applied to the design of high speed mechanisms and also to describe the rules used during the measurement of a part using an integrated CAD and coordinate measuring machine system. The underlying structure is a generic problem solving procedure that can be applied to all aspects of the design process. A new research programme has now commenced to incorporate the human skill and social aspects of design. Through a series of industrial case studies it is hoped to uncover the ‘rules’ governing these human activities. Unlike technical systems these rules are often agreed but unspecified. They arise from educational backgrounds, industrial experience, social responsibilities, status etc. and can greatly influence the way a design discussion progresses and its eventual outcome. The study is aimed at providing both a means of representing the unified design process. This should help to give design groups in industry a greater understanding of the underlying processes that they are handling as well as some of the computer tools that can be used to model and resolved them.

The incorporation of human aspects into a unified design theory

Research into design theory has, up until now, concentrated mostly upon the technical aspects of the process. Techniques have been developed that, on the one hand allow the general processes of design to be described in terms of a global system, whilst on the other, researchers have been addressing and attempting to automate specific detailed design cases through the application of knowledge based techniques applied to CAD/CAM systems. The design process should, however, be considered as a unified activity that incorporates human skill and organisational relationships as well as the available technology. All of these must be matched to the product goals of a given activity. The CAD research group at Brunel University has been creating a design modelling system based upon constraints. Here set theory techniques are used within a knowledge based system to resolve any conflicts between constraining rules. This process has been successfully applied to the design of high speed mechanisms and also to describe the rules used during the measurement of a part using an integrated CAD and coordinate measuring machine system. The underlying structure is a generic problem solving procedure that can be applied to all aspects of the design process. A new research programme has now commenced to incorporate the human skill and social aspects of design. Through a series of industrial case studies it is hoped to uncover the ‘rules’ governing these human activities. Unlike technical systems these rules are often agreed but unspecified. They arise from educational backgrounds, industrial experience, social responsibilities, status etc. and can greatly influence the way a design discussion progresses and its eventual outcome. The study is aimed at providing both a means of representing the unified design process. This should help to give design groups in industry a greater understanding of the underlying processes that they are handling as well as some of the computer tools that can be used to model and resolved them.

Structural Design of Production Risers and Offshore Production Terminals

Offshore production terminals and deepwater risers are seeing increasing use by the offshore oil industry. The structural design of these units presents a unique challenge compared to other offshore systems. Development of design loading conditions and fatigue histories is especially interesting due to the complex interaction of nonlinear riser and vessel dynamics, the statistical nature of maximum loads and the need to consider directionality as well as the magnitude of environmental loading. This paper presents a complete procedure for predicting design loads and fatigue histories for production risers and offshore terminals. The emphasis will be on systems wherein a dedicated vessel is connected to the riser by a rigid mooring arm. A number of structural design configurations will be surveyed. Techniques for preliminary sizing, dynamic analysis, model testing and fatigue analysis will be discussed. The application of this procedure to several specific design cases will be summarized.

Prototype-based Conceptual Design: The SECS System

The paper investigates the problem of design synthesis with prototypes i.e., exemplary solutions in a given field which are obtained by generalization from a set of specific design cases. A framework for organizing prototypical knowledge using multiple models at different abstraction and generalization levels is described. Design synthesis with prototypes is modelled as a recoursive cycle consisting of recalling relevant prototypes, selecting most promising ones and adapting them to current situation. The approach is experimented using SECS a prototype-based system developed for supporting electronic engineers in the high level task of conceptual design of electronic circuits.

Iteration Techniques in Computer Study of Flooded Cylindrical Radiators

The computer study reported at the 65th Meeting of the ASA has been successful in explaining some of the behavior of large, flooded, barrel-stave transducers. This approach has a fundamental weakness in that one does not know a priori the correct source surface-velocity distribution to feed into the computer program. By the time these data are available in a specific design case, it is too late for the computer study to be of value to the designer in the prediction of general behavior. An iteration procedure has been developed, which solves this difficulty by successively modifying the velocity distribution. This is done in such a way that the prescribed source velocity of the active region of the transducer is maintained constant while the inactive region of the model is given nearly any surface shape that is convenient. In general, the result of this procedure is a set of boundary conditions that fails to satisfy the physical requirements. These inconsistencies are used to produce a more reasonable source velocity distribution, which serves as an improved input for a second solution. This process is repeated, each time giving boundary conditions that are more physically acceptable. Program results are compared with experimental model measurements. [Work supported by U. S. Office of Naval Research, Acoustic Programs.]