Simplex-based screening designs for estimating metamodels

The screening method proposed by Morris in 1991 allows to identify the important factors of a model, including those involved in interactions. This method, known as the elementary effects method, relies on a “one-factor-at-a-time” (OAT) design of experiments, i.e. two successive points differ only by one factor. In this article, we introduce a non-OAT simplex-based design for the elementary effects method. Its main advantage, compared to Morris's OAT design, is that the sample size does not collapse when the design is projected on sub-spaces spanned by groups of factors. The use of this design to estimate a metamodel depending only on the (screened) important factors is discussed.     

An optimization approach for the synthesis of recycle and reuse water integration networks

This paper presents a convex mathematical programming model for the global optimization of recycle/reuse water networks. The model is based on a general superstructure that includes the major configurations of interest such as segregation, mixing, recycle, bypass, and treatment of streams needed to satisfy the process and environmental constraints. The basic idea of the model formulation is to consider component balances, treating as optimization variables the individual flowrates. This formulation avoids the bilinear terms that appear when the compositions and total flowrates are considered as optimization variables. The objective function consists in the minimization of the total annual cost including the fresh sources costs, the treatment units costs (which are reformulated as convex functions) and the piping costs. Four examples problems are solved to show the applicability of the proposed model.     

Function-based design synthesis approach to design reuse

In this paper, a design reuse framework with a function-based design synthesis approach is proposed in the context of conceptual product development. Previous researches in design reuse have lacked a comprehensive functional base for knowledge representation and reasoning. The method presented in this paper uses a function-based product information model and a multiple objective optimization model to achieve design reuse. The information model is dependent on a functional core which is the key element vector. It is capable of modeling product information with sufficient abstraction, which in turn facilitates intelligent construction of product platforms. The multiple objective optimization method carries out automated design synthesis and evaluation subject to various design constraints. The approach has been applied in the design of the fan filter unit, a key clean room device. It has achieved intelligent design reuse in product conceptual design with significant rapidity and solution variety.     

A pseudo-random number assignment strategy for the estimation of quadratic metamodels

Whereas an optimal Pseudo-Random Number (PRN) assignment strategy for simulation experiments involving the estimation of linear metamodels currently exists, no such optimal assignment strategy for quadratic metamodels has been proposed. This situation is now rectified by the introduction of a PRN assignment strategy for a quadratic metamodel for 3^k factorial designs. In addition to extending the theory from linear to quadratic metamodels, the proposed PRN strategy is shown to be superior to a number of existing and competing strategies in terms of various variance measures.     

Beyond CFCs: Extending the search for new refrigerants

Previous work in developing environmentally acceptable alternatives to fully halogenated chlorofluorocarbons (CFCs) has concentrated almost exclusively on methane and ethane based compounds. A review of toxicity and boiling point data for a large variety of fluorine compounds reveals additional classes of compounds which may be suitable as refrigerants. Fluorinated derivatives of dimethyl ether and cyclopropane appear to have both low toxicity and suitable boiling points. They also have a relatively simple structure which means that they should have a reasonably good cycle efficiency. Propane based CFCs may also be useful if simpler compounds prove to be unacceptable. Specific compounds that warrant further investigation include bis-difluoromethyl ether (for R114), difluoromethyl dichlofluoromethyl ether (for R113), difluoromethyl fluoromethyl ether (for R11) and hexafluorocyclopropane (for R12). In addition, the compound trifluoroiodomethane may be a useful alternative to R13B1 in fire extinguishers. A cooperative programme of synthesizing and evaluating fluorinated derivatives of dimethyl ether and cyclopropane is recommended.     

A new sampling scheme for developing metamodels with the zeros of Chebyshev polynomials

The accuracy of metamodelling is determined by both the sampling and approximation. This article proposes a new sampling method based on the zeros of Chebyshev polynomials to capture the sampling information effectively. First, the zeros of one-dimensional Chebyshev polynomials are applied to construct Chebyshev tensor product (CTP) sampling, and the CTP is then used to construct high-order multi-dimensional metamodels using the ‘hypercube’ polynomials. Secondly, the CTP sampling is further enhanced to develop Chebyshev collocation method (CCM) sampling, to construct the ‘simplex’ polynomials. The samples of CCM are randomly and directly chosen from the CTP samples. Two widely studied sampling methods, namely the Smolyak sparse grid and Hammersley, are used to demonstrate the effectiveness of the proposed sampling method. Several numerical examples are utilized to validate the approximation accuracy of the proposed metamodel under different dimensions.     

Validating behavioral models for reuse

When using a model to predict the behavior of a physical system of interest, engineers must be confident that, under the conditions of interest, the model is an adequate representation of the system. The process of building this confidence is called model validation. It requires that engineers have knowledge about the system and conditions of interest, properties of the model and their own tolerance for uncertainty in the predictions. To reduce time and costs, engineers often reuse preexisting models that other engineers have developed. However, if the user lacks critical parts of this knowledge, model validation can be as time consuming and costly as developing a similar model from scratch. In this article, we describe a general process for performing model validation for reused behavioral models that overcomes this problem by relying on the formalization and exchange of knowledge. We identify the critical elements of this knowledge, discuss how to represent it and demonstrate the overall process on a simple engineering example.

Inertia and Managerial Intentionality: Extending the Uppsala Model

The Uppsala Internationalization Process Model is the most cited model within the field of international business. However, even with its most recent formulation, the model is predicated on a key set of assumptions about the limiting and releasing mechanisms in a ‘change of state’ decision. The model assumes that uncertainty, risk, lack of trust, and lack of awareness of opportunities are the main constraints, and that the accumulation of experiential knowledge, trust, and market commitment are the main releasing factors that allow a firm to overcome those constraints and progress to a higher state of commitment. We argue that the preceding view may be excessively narrow, and that inertia and managerial intentionality may also play a role as critical limiting and releasing mechanisms, respectively. This development implies that the passage of time and experiential learning may not always have a positive impact on firm internationalization. The extended model proposed in this paper highlights the role of the manager, and brings a contingent element to the model, thus broadening its applicability by providing new insights on issues typically considered outside the realm of the Uppsala model, such as rapidly internationalizing firms, regionalization, mode inertia and mode skipping.     

Extending the imaging volume for biometric iris recognition

The use of the human iris as a biometric has recently attracted significant interest in the area of security applications. The need to capture an iris without active user cooperation places demands on the optical system. Unlike a traditional optical design, in which a large imaging volume is traded off for diminished imaging resolution and capacity for collecting light, Wavefront Coded imaging is a computational imaging technology capable of expanding the imaging volume while maintaining an accurate and robust iris identification capability. We apply Wavefront Coded imaging to extend the imaging volume of the iris recognition application.     

Effective visualisation of design versions: visual storytelling for design reuse

Improving and supporting the process of design knowledge reuse can increase productivity, improve the quality of designs and lead to corporate competitive advantage. Whereas internal knowledge reuse (reusing knowledge from one’s personal memory or experiences) is very effective, external knowledge reuse (reusing knowledge from an external digital or paper archive) often fails. This paper studies the value of the storytelling paradigm in supporting reuse from an external repository. Based on a formalisation of the internal reuse process from ethnographic studies, a prototype system, Corporate Memory (CoMem) is presented, which supports the reuse process, specifically the steps of finding and understanding reusable items. This paper focuses on the ability of designers to understand designs that are found in corporate repositories. It is argued that in order to understand and reuse a found design, the designer needs to see the evolution of that design during the original design process. An Evolution History Explorer module of the CoMem system is presented that uses a storytelling metaphor and lays out versions visually side-by-side. A formal user evaluation of CoMem supports the hypotheses that (1) exploring the evolution of a design improves the reuse process, and (2) that visual storytelling is an effective paradigm for supporting that exploration.     

Extending the boundaries between scheduling and dispatching: hedging and rescheduling techniques

While deterministic scheduling models have been well studied, the use of these models is not well documented in manufacturing environments. Previous research has indicated that deterministic scheduling approaches quickly lose their advantage compared to dispatching rules when processing time uncertainty is present. This research presents the case of a Printed Wiring Board Manufacturer’s drilling operation, which is a group of unrelated parallel machines. The manufacturer wishes to minimise makespan, number of late jobs, total overtime, average machine finishing time and machine utilisation when stochastic uncertainty is present. While deterministic scheduling has been shown to be a good solution approach when processing time variability is low, this research attempts to extend the boundaries in which scheduling is useful by investigating job and machine hedges as well as periodic and event driven rescheduling policies. The success of the approach is evaluated using a simulation model to evaluate the performance over a number of sequential schedules under various distributional assumptions.     

An algebraic approach to targeting waste discharge and impure fresh usage via material recycle/reuse networks

This paper introduces an algebraic procedure that targets material-recycle networks. The problem involves the allocation of process streams and fresh sources to process units (sinks) with the objective of minimizing fresh usage and waste discharge. First, observations from the graphical targeting approach are transformed into algebraic insights. Then, a geometrical transformation is developed to account for the possibility of using impure fresh resources. These insights and geometrical transformations are arranged through a cascade analysis, which identifies and adjusts any recycle infeasibilities so as to maximize the recycle opportunities. A systematic non-iterative algebraic approach is developed to identify rigorous targets for minimum usage of impure fresh resources, maximum recycle of process resources and minimum discharge of waste. These targets are identified a priori and without commitment to the detailed design of the recycle/reuse network. The approach is valid for both pure and impure fresh resources. The devised procedure also identifies the location of the material-recycle pinch point and addresses its significance in managing process sources, fresh usage, and waste discharge. Two case studies are solved to illustrate the ease, rigor, and applicability of the developed targeting technique and its relationship to graphical targeting techniques.     

On the formalization and reuse of scientific research

The reuse of scientific knowledge obtained from one investigation in another investigation is basic to the advance of science. Scientific investigations should therefore be recorded in ways that promote the reuse of the knowledge they generate. The use of logical formalisms to describe scientific knowledge has potential advantages in facilitating such reuse. Here, we propose a formal framework for using logical formalisms to promote reuse. We demonstrate the utility of this framework by using it in a worked example from biology: demonstrating cycles of investigation formalization [F] and reuse [R] to generate new knowledge. We first used logic to formally describe a Robot scientist investigation into yeast (Saccharomyces cerevisiae) functional genomics [f₁]. With Robot scientists, unlike human scientists, the production of comprehensive metadata about their investigations is a natural by-product of the way they work. We then demonstrated how this formalism enabled the reuse of the research in investigating yeast phenotypes [r₁ = R(f₁)]. This investigation found that the removal of non-essential enzymes generally resulted in enhanced growth. The phenotype investigation was then formally described using the same logical formalism as the functional genomics investigation [f₂ = F(r₁)]. We then demonstrated how this formalism enabled the reuse of the phenotype investigation to investigate yeast systems-biology modelling [r₂ = R(f₂)]. This investigation found that yeast flux-balance analysis models fail to predict the observed changes in growth. Finally, the systems biology investigation was formalized for reuse in future investigations [f₃ = F(r₂)]. These cycles of reuse are a model for the general reuse of scientific knowledge.     

Biological treatment and nanofiltration of denim textile wastewater for reuse

This study aims at coupling of activated sludge treatment with nanofiltration to improve denim textile wastewater quality to reuse criteria. In the activated sludge reactor, the COD removal efficiency was quite high as it was 91+/-2% and 84+/-4% on the basis of total and soluble feed COD, respectively. The color removal efficiency was 75+/-10%, and around 50-70% of removed color was adsorbed on biomass or precipitated within the reactor. The high conductivity of the wastewater, as high as 8 mS/cm, did not adversely affect system performance. Although biological treatment is quite efficient, the wastewater does not meet the reuse criteria. Hence, further treatment to improve treated water quality was investigated using nanofiltration. Dead-end microfiltration (MF) with 5 microm pore size was applied to remove coarse particles before nanofiltration. The color rejection of nanofiltration was almost complete and permeate color was always lower than 10 Pt-Co. Similarly, quite high rejections were observed for COD (80-100%). Permeate conductivity was between 1.98 and 2.67 mS/cm (65% conductivity rejection). Wastewater fluxes were between 31 and 37 L/m2/h at 5.07 bars corresponding to around 45% flux declines compared to clean water fluxes. In conclusion, for denim textile wastewaters nanofiltration after biological treatment can be applied to meet reuse criteria.     

Shape detection with vision: implementing shape grammars in conceptual design

Despite more than 30 years of research, shape grammar implementations have limited functionality. This is largely due to the difficult problem of subshape detection. Previous research has addressed this problem analytically and has proposed solutions that directly compare geometric representations of shapes. Typically, such work has concentrated on shapes composed of limited geometry, for example straight lines or parametric curves, and as a result, their application has been restricted. The problem of general subshape detection has not been resolved. In this paper, an alternative approach is proposed, in which subshape detection is viewed as a problem of object recognition, a sub-domain of computer vision. In particular, a general method of subshape detection is introduced based on the Hausdorff distance. The approach is not limited in terms of geometry, and any shapes that can be represented in an image can be compared according to the subshape relation. Based on this approach, a prototype shape grammar system has been built in which the geometry of two-dimensional shapes is not restricted. The system automates the discovery of subshapes in a shape, enabling the implementation of shape rules in a shape grammar. Application of the system is illustrated via consideration of shape exploration in conceptual design. The manipulations of sketched design concepts are formalised by shape rules that reflect the types of shape transformations employed by designers when sketching.     

Paper triboelectric nanogenerator designed for continuous reuse and quick construction

Along with the unceasing growth of worldwide economic and the associated issues on resources,energy and environment,clean energy generating technologies that are based on recyclable materials,if possible,may become the future trend of development.Here,we report the design of a cheap,lightweight,and recyclable single-electrode triboelectric nanogenerator(TENG)that utilizes waste paper as the triboelectric material.Under the current strategy,we successfully developed green energy machines without vastly increasing the mining of various critical minerals around the world.The as-designed TENG could not only collect and convert mechanical energy into electricity with sound efficiency,but also has the merit for continuous reuse and quick construction.The maximum output power density is as high as 171 mW·m^-2 at a resistance of 130 MQ and could be integrated into a book for monitoring reading actions,thus providing a new approach to the low-cost,green and sustainable self-powered electronic systems.     

Extending the permissible control loop latency for the controlled inverted pendulum

A pendulum can be stabilized in its upright position by proportional-plus-derivative (PD) feedback control only if the latency in the control loop is smaller than a certain critical delay. This critical delay is determined by the presence of a fully symmetric triple-zero eigenvalue singularity, a bifurcation of codimension three. We investigate three possible modifications of the PD scheme with the aim of extending the range of permissible delays. Effectively, these modifications introduce another parameter. This additional parameter can be used to continue the triple-zero singularity in four parameters until it gains a higher-order degeneracy imposing a new limit on the permissible delay. It turns out that the most effective modification is to feed back the value of the position with a small (intentional) additional delay on top of the control loop latency.     

Water reuse for irrigated agriculture in Jordan: challenges of soil sustainability and the role of management strategies

Reclaimed water provides an important contribution to the water balance in water-scarce Jordan, but the quality of this water presents both benefits and challenges. Careful management of reclaimed water is required to maximize the nutrient benefits while minimizing the salinity risks. This work uses a multi-disciplinary research approach to show that soil response to irrigation with reclaimed water is a function of the management strategies adopted on the farm by the water user. The adoption of management methods to maintain soil productivity can be seen to be a result of farmers' awareness to potentially plant-toxic ions in the irrigation water (70% of Jordan Valley farmers identified salinization as a hazard from irrigation with reclaimed water). However, the work also suggests that farmers' management capacity is affected by the institutional management of water. About a third (35%) of farmers in the Jordan Valley claimed that their ability to manage salinization was limited by water shortages. Organizational interviews revealed that institutional awareness of soil management challenges was quite high (34% of interviewees described salinization as a risk from water reuse), but strategies to address this challenge at the institutional level require greater development.