Future Design Processes Research Articles

Pressure drop measurements and hydrodynamic model description of SiC foam composites decorated with SiC nanofiber

During the last decade there has been a growing interest in catalytic reactor engineering based on structured catalytic beds. Compared to traditional packed bed reactors, structured catalytic beds provide improved hydrodynamics and catalytic performance. In this context, silicon carbide (SiC) foam materials seems to be a good candidate for use as catalyst support due to their high geometrical surface area (m −1) and open porosity leading to low pressure drop. However, foam structures have a relatively low specific surface area (m 2/g) for performing good anchorage and dispersion of the active phase which is one of the crucial points in catalysis. This study proposes a new type of material which combined the advantage of foam (high porosity) with nanofiber of SiC (high specific surface (m 2/g)). The knowledge of pressure drop characteristics of foam with nanofiber is necessary for the future process design. However, due to the complexity of the geometric shape of new foam materials, up to date, no general relationship exists for the calculation of the pressure drop through different foam matrix and generally, empirical equation with modified parameters of the Ergun's equation were needed to fit the data. This study show that a simple model can be used for the prediction of the pressure drop in the SiC foam with nanofiber through Ergun's equation without using any fitting in order to reconcile experimental data with theory.

A Good Start: Workshop Tackles Space Weather Economics

As I wrote earlier this year, reliable estimates of the economic impacts of a space weather event on technologies have often been seriously lacking (see L. Lanzerotti, Space Weather, 6, S01002, doi:10.1029/2007SW000385, 2008). However, I am happy to note that the Space Studies Board of the U.S. National Research Council took an important step toward setting a framework for achieving some of these “reliable estimates” in a workshop that was held in late May in Washington, D. C. The meeting drew active participation from the academic research community and major government agencies in the National Space Weather Program (http://www.nswp.gov), as well as a significant number of commercial interests large and small. These latter included enterprises that use space weather information for design decisions and/or successful operations, as well as vendors of space weather products and services. The workshop explored several issues related to the economics of space weather. For example, the climatology of space radiation is essential for the design of the long-lived communications satellites that occupy geosynchronous orbit. Current radiation climate models are 30 or more years old and do not reflect major discoveries in the past few decades. Closely tied to this is the absence of reliable information on the statistics of the radiation environment: Are there upper limits to expected flux values, and should designs be based upon such limits (if they are known) or on some lesser (and less expensive to implement) values? What are the design and operations costs for not knowing this information? What are the costs to achieve such information and thus to make future design processes more robust? The policy-oriented participants provided many provocative (and productive) insights on space weather and its economic effects. These included discussions of the prioritization of risks (including space weather) to a business or government activity, as well as the perception of risks to the public. An important realization stressed by several participants was the central role of the complex electricity grid across the nation that underpins essentially all contemporary technologies. What is the risk of a collapse of a major part of the grid under a space weather event? Equally important, can this risk and its economic consequences be examined without causing a “sky is falling” mentality? Where does a space weather risk to the grid rank with respect to other risks, natural and man-made? This workshop was an important initial forum for assembling a diverse and very engaged group of individuals and organizations centrally involved with space weather concerns. The discussions illuminated numerous unresolved engineering, science, and policy issues related to the economics of space weather. However, solid economic information was often lacking in the discussions, partly because of the absence of such data and partly because of proprietary concerns. I hope the National Research Council can use this initial endeavor as the beginning of a more extensive process to delve into space weather economics. Louis J. Lanzerotti is editor of Space Weather and a distinguished research professor of physics at the New Jersey Institute of Technology.

3-D Applied Element Method for PP-Band Retrofitted Masonry

Masonry, through its long history, is widespread used around the world and still remains a main building material in many places especially developing countries. However a poorly designed masonry is known as brittle and susceptible to earthquakes. To improve masonry seismic capacity, polypropylene band retrofitting technique was purposed based on economic point of view and local availability of material and skilled labor. In this study, we proposed the 3-D Applied Element Method as an analysis tool to help understanding the polypropylene band retrofitted masonry behavior which will be benefit in the future design process. Unlike the previous version, 3-D Applied Element Method elements can be any rectangular prism which helps reducing the number of elements. Brick and mortar springs are represented by using different spring properties. Nonlinear constitutive law of the mortar spring employed the Gambarotta model which considers the material softening. Polypropylene band is modeled as beam element using conventional plastic constitutive law connected together with the masonry by elastic spring representing the polypropylene band to brick connector. The numerical simulation of non-retrofitted and retrofitted out December 2007, Bangladesh New Technologies for Urban Safety of Mega Cities in Asia of plane wallets shows that with the suitable selected parameter the behavior of masonry can be closely reproduced.

PHASE EQUILIBRIUM FOR SUPERCRITICAL CO2 AND THE METHYL ESTERIFIED PRODUCT FROM SOYBEAN OIL DEODORIZER DISTILLATE

ABSTRACT In order to study the feasibility of using supercritical CO2 (SC‐CO2) to concentrate natural tocopherols from soybean oil deodorizer distillate (DOD), the vapor–liquid phase equilibrium data were determined for SC‐CO2 and methyl esterified DOD (ME‐DOD) at 40C and in the pressure range of 9.7–16.2 MPa. A vapor and liquid phase circulation apparatus was employed. The samples from the liquid and vapor phases were analyzed by gas chromatography and high‐performance liquid chromatography methods. According to the determined data, the distribution coefficient and separation factor were calculated and discussed. The results showed that the separation factor between tocopherols and fatty acid methyl esters was from 2.5 to 3.8 at 40C and 9.7–16.2 MPa, which is fundamental and necessary for future process designs.

The 4Cs model of exemplary construction projects

PurposeThe purpose of this paper is to highlight the key characteristics of the highest‐performing construction projects, so that future procurement, briefing, design and construction management processes can be improved in the light of these experiences.Design/methodology/approachWorkshops were carried out in Australia, Singapore and the USA involving 40 senior participants, representing a good cross‐section of the stakeholder interests around construction. These individuals were each asked to identify the best construction project with which they had been involved at any point in their careers and to identify the major reasons for its success.FindingsA synthesis is provided of the characteristics that characterise the exemplary projects cited by the workshop participants. These are typified by the “4Cs”, namely constraints driving collaboration and creativity, ideally leading to community benefits. The 17 exemplars provided by the participants show project teams facing demands that act to break the dysfunctional paradigm of normal practice, so allowing refreshing and motivating actions to follow. This schema is reinforced by the three case study vignettes that illustrate in more detail the factors at work and their interactions. Linkage to prominent issues apparent in the literatures related to procurement, briefing, design and construction management are shown, together with pointers as to the connections between these issues as experienced in specific real world, project situations. In particular, the potentially pervasive impact of selective priority‐setting is highlighted.Practical implicationsThis paper provides a glimpse of how construction operates at its best, the industry explicitly contributing to, and getting credit for, adding value to society economically, but also culturally, socially and environmentally.Originality/valueThe work reported on here covers 17 mini‐cases and three fuller cases, all drawn from three countries. Further work to build additional cases from a wider range of countries would test the broad outline of the 4Cs model and increase one's understanding of the dynamic mechanisms at work.

Designing Today's Urban Arterials

The recent design for the reconstruction of Lake Street in Minneapolis, Minnesota, provides the canvas for an illustration of the challenges in delivering a context-sensitive project within the center of a city where a dense built environment already exists. Lake Street's reconstruction involves a county-initiated design, the city's and the community's response, and the participation of a foundation in achieving a design linked to how the community can grow and prosper and how people interact with one another. A street is an integral part of community life. Its design can hinder or support a community. The Lake Street design process shows that this understanding, along with best intentions, is not always enough. Strong institutional biases and conventions drive street design processes toward traffic-moving outcomes and away from community-building outcomes. These biases can be countered only with deliberate forethought and persistent attention and action. This paper attempts to provide insights into how community goals and street design processes become misaligned. Through a case study approach reviewing a current design, it also offers strategies showing how future street design processes must be more than an act of engineering. Good street design is an act of community planning, with engineering expertise helping to execute those plans. Once those involved in street design processes begin to recognize this, the approach will be different, the discussions will be different, and above all, the outcomes will be different.

Risk-informed design guidance for future reactor systems

Future reactor designs face an uncertain regulatory environment. It is anticipated that there will be some level of probabilistic insights in the regulations and supporting regulatory documents for Generation-IV nuclear reactors. Central to current regulations are design basis accidents (DBAs) and the general design criteria (GDC), which were established before probabilistic risk assessments (PRAs) were developed. These regulations implement a structuralist approach to safety through traditional defense in depth and large safety margins. In a rationalist approach to safety, accident frequencies are quantified and protective measures are introduced to make these frequencies acceptably low. Both approaches have advantages and disadvantages and future reactor design and licensing processes will have to implement a hybrid approach. This paper presents an iterative four-step risk-informed methodology to guide the design of future-reactor systems using a gas-cooled fast reactor emergency core cooling system as an example. This methodology helps designers to analyze alternative designs under potential risk-informed regulations and to anticipate design justifications the regulator may require during the licensing process. The analysis demonstrated the importance of common-cause failures and the need for guidance on how to change the quantitative impact of these potential failures on the frequency of accident sequences as the design changes. Deliberation is an important part of the four-step methodology because it supplements the quantitative results by allowing the inclusion in the design choice of elements such as best design practices and ease of online maintenance, which usually cannot be quantified. The case study showed that, in some instances, the structuralist and the rationalist approaches were inconsistent. In particular, GDC 35 treats the double-ended break of the largest pipe in the reactor coolant system with concurrent loss of offsite power and a single failure in the most critical place as the DBA for the emergency core cooling system. Seventeen out of the 45 variations that we considered violated this DBA, but passed the probabilistic screening criteria. Using PRA techniques, we found that the mean frequency of this accident was very low, thus indicating that deterministic criteria such as GDC 35 must be reassessed in the light of risk insights.

Deep desulfurization: reactions, catalysts and technological challenges

Very stringent regulation in the maximal S content of gas oil have led to an intense activity of research dealing with all the aspects of desulfurization. The design of future processes is based on the identification of the refractory sulfur compounds and the knowledge of their individual reactivity and in the presence of inhibitors, as illustrated in this paper. This knowledge have oriented the research towards new catalysts such as molybdenum sulfide supported on zeolites, combination of sulfide and noble metal catalysts, and molybdenum carbides. Non-catalytic approaches like charge transfer complex were also examined. This paper summarises these various aspects of desulfurization.

Aerobic and anaerobic ethanol production by Mucor circinelloides during submerged growth.

The dimorphic organism Mucor circinelloides is currently being investigated as a potential host for heterologous protein production. The production of ethanol on pentose and hexose sugars was studied in submerged batch cultivations to further the general knowledge of Mucor physiology, with a view to the minimisation or elimination of the by-product ethanol for future process design. Large amounts of ethanol were produced during aerobic growth on glucose under non-oxygen limiting conditions, which is indicative of M. circinelloides being a Crabtree-positive organism. Ethanol production on galactose or xylose was less significant. The response of the organism to increased ethanol concentrations, both as the sole carbon source and in the presence of a sugar, was investigated in terms of biomass formation and morphology.

Overview of advanced structural and reliability techniques for optimum design of fixed offshore platforms

The paper addresses the increasing use of advanced structural and reliability techniques in design optimisation of fixed offshore platforms. Recent changes in regulatory and contract practices within the offshore industry coupled with developments in structural and reliability methods and increased hardware capacity create a suitable framework for increased design optimisation. The paper examines the current impact of advanced structural analysis techniques at component and system level and examines how recent developments in structural system reliability techniques are likely to affect the design process in future. Areas that need to be addressed before we are able to maximise the benefits from the use of these techniques are discussed together with recommendations for a more effective integration in the design process.

Multicriteria Structural Optimization as a Technique for Quality Improvement in the Design Process

Abstract: After being able to determine the structural behavior by means of finite methods (e.g., finite elements, finite differences, boundary elements), an important goal of engineering activities is to improve and to optimize technical designs, structural assemblies, and components. The task of vector or multicriteria structural optimization is to support the engineer in finding the best‐possible design alternatives of specific structures. The “best‐possible” or “optimal” structure is the one that corresponds to the designer's desired concept, meeting at the same time all kinds of multidisciplinary requirements referring to manufacturing, erecting, operating, etc. In comparison with the trialand‐error method generally used in the engineering environment and based on an intuitive heuristic approach, the determination of optimal solutions by means of correctly applied optimization procedures is more reliable and efficient. These procedures will be a need in the design process in future, and they are already increasingly entering industrial practice. Two examples of real‐life structures are introduced in this paper.

A mathematical model for spin coating of polymer resists

The success of lithographic processes in microelectronics fabrication depends on the reproducible generation of desired polymer resist film thickness and profile uniformity. Numerous process variables affect the outcome of spin coating of resists on wafers. A thorough understanding of the intricate interdependence of process parameters is essential to guide future process design and improvement. A mathematical model is derived to elucidate the dominant mechanisms governing film formation. The non-Newtonian character of the resist solution is taken into account, as well as the changes in resist viscosity and solvent diffusivity with changing polymer concentration. Results obtained from this model show that polymer film thickness is controlled by convective radial flow of the resist solution and solvent evaporation. The former process governs film thickness during the early stages of the process, while the latter becomes significant in later stages. The model accurately describes the experimentally observed dependence of film thickness on the variables affecting the spin-coating process.