Van Der Vorst Research Articles

An Enhancement of the Accuracy of the BiCGStab Method for Solving Linear Systems with Single or Multiple Right-Hand Sides

In this paper, we present a technique to improve the convergence of the biconjugate gradient stabilized (BiCGStab) method. This method was developed by Van der Vorst for solving nonsymmetric linear systems with a single right-hand side. The global and block versions of the BiCGStab method have been proposed for solving nonsymmetric linear systems with multiple right-hand sides. Using orthogonal projectors to minimize the residual norm in each step, we get an enhancement of the convergence of each version of the BiCGStab method. The considered methods are BiCGStab, global BiCGStab, and block BiCGStab methods, noted, respectively, as Gl-BiCGStab and Bl-BiCGStab. To show the performance of our enhanced algorithms, we compare them with the standard, global, and block versions of the well-known generalized minimal residual method (GMRES).

Coron's problem for the critical Lane-Emden system

We address the solvability of the critical Lane-Emden system in a smooth bounded domain with a small spherical hole of radius ϵ>0. We prove that the system admits a family of positive solutions that concentrate around the center of the hole as ϵ→0, obtaining a concrete qualitative description of the solutions as well. To the best of our knowledge, this is the first existence result for the critical Lane-Emden system on a bounded domain, while the non-existence result on star-shaped bounded domains has been known since the early 1990s due to Mitidieri (1993) [30] and van der Vorst (1992) [36].

Japan, the European Union and Global Governance by Eiji Ogawa et al.

Reviewed by: Japan, the European Union and Global Governance by Eiji Ogawa et al. Marie Söderberg (bio) Japan, the European Union and Global Governance. Edited by Eiji Ogawa, Kolja Raube, Dimitri Vanoverbeke, and Jan Wouters with Camille Van der Vorst. Edward Elgar, 2021. xii, 243 pages. $125.00, cloth; $40.00, E-book. The literature on EU-Japan relations, especially in the field of global governance, has so far been rather limited. The reason for this, from a historical point of view, is that those relations, always much talked about, have been weak with few mutual initiatives or actions. The nine chapters in this [End Page 259] book offer different angles on the EU-Japan relationship. Their goal is to understand and assess the growing cooperation and solidarity between the EU and Japan, not only in the field of economics where relations have been intensive, but also in the field of politics, in the midst of growing global tension. While other books have taken broader perspectives such as geopolitical changes with the rise of China and crises of liberalism and the U.S. role in changing EU-Japan relations, 1 this book focuses more on the EU and Japan as actors and not on in-depth analyses of surrounding factors that affect the relationship. In 2018 both an economic partnership agreement (EPA) and a strategic partnership agreement (SPA) based on shared norms and values were signed. And in 2019 the signing of the Partnership on Sustainable Connectivity and Quality Infrastructure with its objective to "promote free, open, rule based, fair, nondiscriminatory and predictable regional and international trade and investment" aimed at cooperation in the development of infrastructure in Europe and Asia and formation of an alternative to the Chinese Belt and Road Initiative (BRI). What is driving all these new EU-Japan initiatives and how should we assess their impact on global governance? That is the question the book wants to answer. The volume takes a multidisciplinary view, mostly from various economic perspectives, even if economics and politics nowadays seem more interconnected than ever. Sometimes the relationship is seen here from an EU perspective and sometimes from a Japanese one. The first part of the book situates EU-Japan cooperation in global governance. The chapter by Kolje Raube, Alex Andrione-Moyne, and Jan Wouters frames cooperation within the EU's multilateral approach to global governance where the EU integration project itself can be seen as a kind of multilateral cooperation. Although EU policy objectives were considered to be best served in an international system based on rules and multilateralism, this has not ruled out other forms of cooperation such as bilateralism, and here EU-Japan relations constitute a key strategic relationship. Recently, however, non-Western powers have gained more power and started to question the existing multilateral order. So did the United States under the administration of Donald Trump and so also have certain European states. The EU faces problems adapting to this new world order. This chapter looks at the EU's normative commitment to multilateralism and its international practice in times of contestation. It shows how the EU is reorienting toward an "interest focused" geopolitical outlook where Japan can be seen as an anchoring partner in Asia. Ryo Oshiba mainly takes a historical perspective to research Japanese involvement in financial governance in the World Bank and the G7 summits. [End Page 260] His chapter looks for lessons learned from Japan's past experience with the Asian financial crisis, among others. Some conclusions are drawn about the role Japan can play in global governance. According to this author, the Japanese experience in development finance indicates that Japan will be able to present a development model that synthesizes the Chinese and Western models. Both the Japanese East Asian Miracle model and the Chinese model emphasize the role of government in promoting economic growth. The author forgets to point out that the East Asian Miracle report was heavily criticized at the time of its publication (1993) and proof was presented that it might not have been economic intervention by governments that created growth in East Asia. Rather, growth was created through superior accumulation of physical and human capital and the...

A posteriori superlinear convergence bounds for block conjugate gradient

In this paper, we extend to the block case the a posteriori bound showing superlinear convergence of the conjugate gradient method developed by van der Vorst and Vuik in [J. Comput. Applied Math., 48 (1993), pp. 327–341]. That is, we obtain similar bounds but now for the block conjugate gradient method. We also present a series of computational experiments, illustrating the validity of the bound developed here as well as the bound by Simoncini and Szyld from [SIAM Review, 47 (2005), pp. 247–272] using angles between subspaces. Using these bounds, we make some observations on the onset of superlinearity and how this onset depends on the eigenvalue distribution and the block size.

Unravelling the role of vascular chemR23 expression in atherosclerosis

Background and Aims: Chemokine receptors are important in perpetuating chronic vascular inflammation. Our published work (Van der Vorst et al., ATVB 2019) showed that hematopoietic deficiency of the chemokine like receptor ChemR23 increases the proportion of alternatively activated M2 macrophages and attenuates pDC recruitment to lymphatic organs and atherosclerotic lesions, in murine models. However, conflicting results in systemic ChemR23-deficient animals (Laguna-Fernandez et al., Circulation 2018) suggests ChemR23 has a diverse role within atherosclerosis. Therefore, we investigated the role of ChemR23 on arterial endothelial and smooth muscle cells.

STRATEGI PENINGKATAN KUALITAS PRODUK DALAM RANTAI PASOK KOMODITI PISANG DI PROVINSI BENGKULU

A well-being supply chain system will affect on the sustainability of the production and consumer’s satisfaction. Consumer’s need will be fulfilled if the served quality is in the accordance with consumer’s expectations. This study aimed to identify banana supply chains, determine product quality attributes, and strategies for improving the quality of banana products. The methods used were Van der Vorst supply chain management framework, Quality Function Deployment (QFD), and Analytical Hierarchy Process (AHP). The research results exposed that banana supply chain consisted farmers, traders, industries, retailers, and consumers. The dominant quality factors on thise supply chain were the harvest planning (0.24) and harvesting technique (0.19) for fresh bananas; the frying (0.28) and the packaging (0.20) for sale banana; the frying (0.28) and the packaging (0.17) for banana chips. Meanwhile, the quality attributes for fresh bananas were fruit maturity and damage level, for sale bananas were taste and texture, and for banana chips were taste and level of cracked chips. The proposed strategies to improve product quality in the banana comodity supply chain were an increase ability or skill in the production process for each actor (0.25), using standards in the product production process (0.22), make a explicit contractual agreements between actors regarding product quality (0.21), establish a structur farmer group institutions (0.13), optimizing local wisdom (0.10) and the government’s role in assisting farmer and industrial development (0.08). Keywords: banana products,quality improvement, supply chain

One rule for one, and a different rule for another: The case of the Parental Rules about Alcohol Questionnaire

Background. The parental rules about alcohol questionnaire (Van der Vorst et al., 2005, 2006) uses 10 items to assess how strictly adolescents believe the rules set by their parents about drinking are. An increasing body of literature has attested to the importance of rule setting in the prevention of problematic alcohol use among adolescents. A recent study proposed a two-factor solution in place of the hypothesized unidimensional one, with factors assessing non-normative, and normative rules. Methods. The present study used five waves of data to examine the structure of the scale, and how well it relates to a measure of heavy episodic drinking (HED). Participants in Waves one to four {10,954–9,383} were substantively more numerous than those at wave five (N = 2,332). Results. Confirmatory Factor Analyses did not support either the ten-item hypothesized model, nor the proposed two-factor solution. Results of exploratory factor analyses all pointed to a one factor solution. Using Modification Indices, we obtained a good-fitting, five-item unidimensional model in Waves one to four. At wave five, a good fitting unidimensional model was obtained with the dropping of a further item. Scores on this shortened scale were internally consistent, correlated highly with scores on the original ten-item version, and correlated to a similar degree as the original 10-item measure, with scores on a HED measure. Conclusion. Further work is required in assessing the properties of this scale across cultures and samples before definitively determining that two factors best represent parental rules.

Exploratory and confirmatory factor analysis of the parental rules toward adolescent drinking questionnaire: Two factors are better than the original one

The parental rules toward drinking questionnaire (PRQ; Van der Vorst et al., 2005) assesses strictness toward adolescent drinking situations. The aim of the current study was to address a gap in the literature on the psychometric testing and evaluation of the factor structure of the PRQ. The current sample consisted of Dutch adolescents (N = 2922) who participated in a randomized control trial with three intervention groups (parent, student, and parent + student) and a control. PRQ and frequency of alcohol use (past month and year) were measured at baseline (T1) and 12 months later (T2). Results from Exploratory and Confirmatory Factor Analyses revealed two reliable factors: (a) rules about normative drinking situations and (b) rules about non-normative drinking situations (both αs ≥ 0.88). Regression analyses conducted to examine the prospective effects of the interventions revealed that both parent conditions predicted increases in strictness toward normative drinking situations relative to the control condition, while only the parent + student condition affected the original PRQ (single factor). Further, the normative subscale predicted increases in drinking (past month and year), as did the original PRQ. Significant effects with the normative subscale indicate that rules toward these drinking situations are ones that account for the effects in the original PRQ, and that the original PRQ can mask effects. The results illustrate that the PRQ is multidimensional. The effects of the normative subscale suggest that intervention efforts should focus on preventing drinking situations that parents normally permit their adolescents to engage in.

Analisis Risiko Rantai Pasok Pestisida Pada PT. Agricon

One solution to increase agricultural production is to overcome pests and diseases by using pesticides, which has an influence on pesticides’ availability. Therefore, it is necessary to analyse the performance and risks that arise in the pesticide supply chain. This study aimed to identify and analyse supply chain mechanisms and the performance of pesticide supply chain, and to identify and analyse risks of pesticide supply chain. The Van der Vorst method was used to analyse the structure of supply chain networks, supply chain business processes, supply chain management, and supply chain resources. The results of performance measurement using SCOR model showed that there were still around 0.61% of orders that were not fully fulfilled; the order fulfillment cycle time was 12 days; the upside supply chain flexibility matrix was ​​three days; and the upside supply chain adaptability matrix was ​​11.72%. Based on these results, the performance value of pesticide supply chain was 52.69% and falls into bad (unacceptable) category. These results indicate that there were still performance attributes that were not optimal. There were still lost of opportunities because the company targets were not fulfilled, which had an impact on profit loss. Risk identification using the FMEA-HOR 1 method, from 40 risk events and 24 risk agents, 10 priority of risk agents were obtained that needed to be mitigated so that the pesticides supply chain could run effectively and efficiently. Keywords : pesticides, supply chain mechanisms, performance, risk

Is sedentary behavior associated with dysglycemia in youth with obesity?

Background and Hypothesis: The childhood obesity epidemic is linked with an increase in dysglycemia and type 2 diabetes (T2D) amongst youth.i Adolescence is associated with decreased levels of physical activityii, however, there is a paucity of research investigating physical activity measures and dysglycemia in youth. We hypothesize that decreased physical activity and/or increased sitting time is positively correlated with dysglycemia.
 Project Methods: Study participants were youth aged 10-21y with a BMI >85th percentile for age and gender. Accelerometers (activPAL) and the FELS Physical Activity Questionnaire (FELS PAQ) were used to assess objective and selfreported physical activity levels. Glucose tolerance was assessed with 2-hour oral glucose tolerance tests (OGTT). Independent t-tests were used to compare physical activity levels for participants with normal glucose tolerance (NGT) and dysglycemia. Correlation analysis was performed to evaluate relationships between measures of physical activity and OGTT measures. 
 Results: Participants with NGT (N=27) and dysglycemia (N=26) had comparable demographics; age, race, and ethnicity. Hemoglobin A1c (HbA1c) (p =0.002), average fasting glucose (p<0.00), indices of insulin resistance (HOMA-IR) (p=.023), insulin secretion (disposition index, DI, a marker of risk for T2D) (p=.008), 2-hour-OGTT measures for glucose (p=.004) and insulin (p=.002) differed between groups. There were not group differences for objective or selfreported measures of physical activity. For the entire cohort, sitting time was positively associated with OGTT 2hr glucose (r=.38, p=.03). However, a subgroup analysis showed that the association between sitting time and OGTT 2hr glucose was significant in the dysglycemia group only (r =.64, p=.006, vs r =.016, p=.95 for NGT group). Self-reported measures of activity (Likert scores) and OGTT measures for insulin and glucose were positively correlated. 
 Conclusion and Potential Impact: Increased sitting time is associated with impaired glucose tolerance in youth with obesity at risk for T2D.
 iVan der Aa MP, Fazeli Farsani S, Knibbe CA, de Boer A, van der Vorst MM. Population-Based Studies on the Epidemiology of Insulin Resistance in Children. J Diabetes Res. 2015;2015:362375.
 iiDumith SC, Gigante DP, Domingues MR, Kohl HW. Physical activity change during adolescence: a systematic review and a pooled analysis. International Journal of Epidemiology. 2011;40(3):685-98. 

Explaining discrepancies in self-reported quality of life in frail older people: amixed-methods study

Most research on (multidimensional) frailty focuses on deficits and risks of adverse outcomes. However, frail older people can still report positive outcomes, such as arelatively high QoL. In order to develop more positively oriented prevention strategies, this exploratory study aimed (a)to identify characteristics related to QoL among frail older people; and (b)to explain discrepancies between higher and lower levels of QoL, with aspecific focus on strengths frail older people with ahigher QoL still may have. Quantitative and qualitative data was gathered by means of semi-structured interviews with Flemish community-dwelling, frail older people with higher (n = 16) and lower QoL levels (n = 18). Quantitative analyses showed that frail older people with ahigher QoL were older, had lower levels of psychological frailty, and reported higher meaning in life compared to those with alower QoL. Outcomes of qualitative analysis showed that participants in the high QoL subgroup adapted more effectively to difficulties, had more things in prospect, performed more activities, and were more satisfied with their social network compared to the low QoL subgroup. To conclude, this exploratory study suggests possibilities to promote and improve QoL by strengthening specific resources among frail older people.Please note that an English version of this article has been published in BMC Geriatrics: van der VorstA, Zijlstra GAR, De WitteN, Vogel RGM, Schols JMGA, Kempen GIJM, D‑SCOPE Consortium. Explaining discrepancies in self-reported quality of life in frail older people: amixed-methods study. BMC Geriatr. 2017;17(1): 251. https://doi.org/10.1186/s12877-017-0641-y .

Morse–Floer theory for superquadratic Dirac equations, I: relative Morse indices and compactness

In this paper and its sequel (Isobe in Morse–Floer theory for superquadratic Dirac equations, II: construction and computation of Morse–Floer homology, 2016), we study Morse–Floer theory for superquadratic Dirac functionals associated with a class of nonlinear Dirac equations on compact spin manifolds. We are interested in two topics: (i) relative Morse indices and its relation to compactness issues of critical points; (ii) construction and computation of the Morse–Floer homology and its application to the existence problem for solutions to nonlinear Dirac equations. In this part I, we focus on the topic (i). One of our main results is a compactness of critical points under the boundedness assumption of their relative Morse indices which is an analogue of the results of Bahri–Lions (Commun Pure Appl Math 45:1205–1215, 1992) and Angenent–van der Vorst (Math Z 231: 203–248, 1999) for Dirac functionals. To prove this, we give an appropriate definition of relative Morse indices for bounded solutions to \(\mathsf {D}_{g_{\mathbb {R}^{m}}}\psi =|\psi |^{p-1}\psi \) on \(\mathbb {R}^{m}\). We show that for \(m\ge 3\) and \(1<p<\frac{m+1}{m-1}\), the relative Morse index of any non-trivial bounded solution to that equation is \(+\infty \). We also give some useful properties of the relative Morse indices of Dirac functionals which will be used in the study of the topic (ii) above.

Exergetic sustainability assessment of batch versus continuous wet granulation based pharmaceutical tablet manufacturing: a cohesive analysis at three different levels

Download options Please wait... Supplementary files Supplementary information PDF (215K) Article information DOI https://doi.org/10.1039/C3GC41185K Article type Paper Submitted 18 Jun 2013 Accepted 04 Sep 2013 First published 04 Sep 2013 Download Citation Green Chem., 2013,15, 3039-3048 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Exergetic sustainability assessment of batch versus continuous wet granulation based pharmaceutical tablet manufacturing: a cohesive analysis at three different levels W. De Soete, J. Dewulf, P. Cappuyns, G. Van der Vorst, B. Heirman, W. Aelterman, K. Schoeters and H. Van Langenhove, Green Chem., 2013, 15, 3039 DOI: 10.1039/C3GC41185K To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Wouter De Soete Jo Dewulf Philippe Cappuyns Geert Van der Vorst Bert Heirman Wim Aelterman Kris Schoeters Herman Van Langenhove

Thermodynamics and the destruction of resources

Introduction Bhavik R. Bakshi, Timothy Gutowski and Dusan Sekulic Part I. Foundations: 1. Thermodynamics: generalized available energy and availability or exergy Elias Gyftopoulos 2. Energy and exergy: does one need both concepts for a study of resources use Dusan Sekulic 3. Accounting for resource use via thermodynamics Bhavik R. Bakshi, Anil Baral and Jorge L. Hau Part II. Products and Processes: 4. Material separation and recycling Timothy Gutowski 5. Entropy based metric for transformational technologies development Dusan Sekulic 6. Thermodynamic analysis of resources used in manufacturing processes Timothy Gutowski and Dusan Sekulic 7. Case studies in energy use to realize ultra-high purities in semiconductor manufacturing Eric Williams, Nikhil Krishnan and Sarah Boyd 8. Energy resources and use: the present (2008) situation, possible sustainable paths to the future and the thermodynamic perspective Noam Lior Part III. Life Cycle Assessments and Metrics: 9. Using thermodynamics and statistics to improve the quality of life cycle inventory data Bhavik R. Bakshi, Hangjoon Kim and Prem K. Goel 10. Developing sustainable technology: metrics from thermodynamics Geert Van der Vorst, Jo Dewulf and Herman Van Langenhove 11. Entropy production and resource consumption in life cycle assessments Stefan Gossling-Reisemann 12. Exergy and material flow in industrial and ecological systems Nandan Ukidwe and Bhavik R. Bakshi 13. Materials flow analysis and input-output analysis: a synthesis Shinichiro Nakamura Part IV. Economic, Social Industrial, Eco Systems: 14. Early development of input-output analysis of energy and ecologic systems Bruce Hannon 15. Exergoeconomics and exergoenvironmental analysis George Tsatsaronis 16. Entopy, economics and policy Matthias Ruth 17. Integration and segregation in a population - a thermodynamicist's view Mueller Ingo 18. Exergy use in ecosystems analysis: background and challenges Roberto Pastres and Brian D. Fath 19. Thoughts on the application of thermodynamics to the development of sustainability science Timothy Gutowski, Dusan Sekulic and Bhavik R. Bakshi.

Novel numerical methods for time-space fractional reaction diffusion equations in two dimensions

We consider time-space fractional reaction diffusion equations in two dimensions. This equation is obtained from the standard reaction diffusion equation by replacing the first order time derivative with the Caputo fractional derivative, and the second order space derivatives with the fractional Laplacian. Using the matrix transfer technique proposed by Ilic, Liu, Turner and Anh [Fract. Calc. Appl. Anal., 9:333--349, 2006] and the numerical solution strategy used by Yang, Turner, Liu, and Ilic [SIAM J. Scientific Computing, 33:1159--1180, 2011], the solution of the time-space fractional reaction diffusion equations in two dimensions can be written in terms of a matrix function vector product $f(A)b$ at each time step, where $A$ is an approximate matrix representation of the standard Laplacian. We use the finite volume method over unstructured triangular meshes to generate the matrix $A$, which is therefore non-symmetric. However, the standard Lanczos method for approximating $f(A)b$ requires that $A$ is symmetric. We propose a simple and novel transformation in which the standard Lanczos method is still applicable to find $f(A)b$, despite the loss of symmetry. Numerical results are presented to verify the accuracy and efficiency of our newly proposed numerical solution strategy. References D. Baleanu, Z. B. Guvenc, J. A. T. Machado. (Eds.) New Trends in Nanotechnology and Fractional Calculus Applications. Springer, 2010. R. E. Ewing, T. Lin and Y. Lin. On the accuracy of the finite volume element method based on piecewise linear polynomials. SIAM J. Numerical Analysis 39(6):1865--1888, 2002. doi:10.1137/S0036142900368873 M. Ilic, F. Liu, I. Turner, and V. Anh. Numerical approximation of a fractional-in-space diffusion equation (II)---with nonhomogeneous boundary conditions. Fract. Calc. Appl. Anal., 9:333--349, 2006. http://hdl.handle.net/10525/1287 R. Klages, G. Radons, I. M. Sokolov. (Eds.) Anomalous Transport: Foundations and Applications. Wiley, 2008. Y. Lin and C. Xu. Finite difference/spectral approximations for the time-fractional diffusion equation. J. Comp. Phys., 225:1533--1552, 2007. doi:10.1016/j.jcp.2007.02.001 I. Podlubny. Fractional Differential Equations. Academic Press, New York, 1999. Y. Saad. Analysis of some Krylov subspace approximations to the matrix exponential operator. SIAM J. Numer. Anal., 29:209--228, 1992. doi:10.1137/0729014 J. Sabatier, O. P. Agrawal, J. A. T. Machado. (Eds.) Advances in fractional calculus: Theoretical developments and applications in physics and engineering. Springer, 2007. V. Simoncini and D. B. Szyld. Recent computational developments in Krylov subspace methods for linear systems. Numer. Linear Algebra Appl., 14:1--59, 2007. doi:10.1002/nla.499 H. A. van der Vorst. An iterative solution method for solving $f(A)x=b$ using Krylov subspace information obtained for the symmetric positive definite matrix $A$. J. Comput. Appl. Math., 18:249--263, 1987. doi:10.1016/0377-0427(87)90020-3 Q. Yang, F. Liu, and I. Turner. Stability and convergence of an effective numerical method for the time-space fractional Fokker--Planck equation with a nonlinear source term. International Journal of Differential Equations, Article ID 464321, 22 pages, 2010. doi:10.1155/2010/464321 Q. Yang, F. Liu, and I. Turner. Numerical methods for fractional partial differential equations with Riesz space fractional derivatives. Applied Mathematical Modelling, 34:200--218, 2010. doi:10.1016/j.apm.2009.04.006 Q. Yang, I. Turner, F. Liu, and M. Ilic. Novel numerical methods for solving the time-space fractional diffusion equation in 2D. SIAM J. Scientific Computing, 33:1159--1180, 2011. doi:10.1137/100800634

A Systematic Evaluation of the Resource Consumption of Active Pharmaceutical Ingredient Production at Three Different Levels

In this paper, the development and the advantages of a methodology which allows the systematic assessment of the environmental impact on the resource side of specific pharmaceutical production processes with limited data entry is presented. The quantification of the process-specific mass and energy balances over three different system boundaries (process, gate-to-gate, and cradle-to-gate) is based on the methodology explained in Van der Vorst et al. (Ind. Eng. Chem. Res.2009, 48(11), 5344-5350). These mass and energy balances are now coupled with the thermodynamic term exergy allowing the quantification of the resource efficiency at the process and gate-to-gate level and the environmental impact at the cradle-to-gate level. The advantages of such a calculation tool for the resource evaluation are illustrated with five consecutive pharmaceutical production steps which are part of the galantamine (anti-Alzheimer medication) pathway. It is shown that such a quantitative and systematic evaluation tool allows a detailed and relatively fast evaluation of the resource efficiency of active pharmaceutical ingredient (API) production processes at the three different levels. Combining thermodynamics and the systematic data inventory methodology for the quantification of the resource efficiency first allows results to be merged into a single impact value (exergy loss/mol API or CEENE/mol API) for fast benchmarking and evaluation of different API production processes. Second, it also allows results to be divided over different categories depending on the users' interest and make thorough analysis of processes in order to pinpoint process improvements and quantitatively justify the introduction of second generation production processes or production techniques.

Improving the parallel performance of a domain decomposition preconditioning technique in the Jacobi–Davidson method for large scale eigenvalue problems

Most computational work in Jacobi–Davidson [G.L.G. Sleijpen, H.A. van der Vorst, A Jacobi–Davidson iteration method for linear eigenvalue problems, SIAM J. Matrix Anal. Appl. 17 (1996) 401–425], an iterative method for large scale eigenvalue problems, is due to a so-called correction equation. In [M. Genseberger, G.L.G. Sleijpen, H.A. van der Vorst, Domain decomposition in Jacobi–Davidson for PDE related eigenvalue problems, in preparation] a strategy for the approximate solution of the correction equation was proposed. This strategy is based on a domain decomposition preconditioning technique in order to reduce wall clock time and local memory requirements. This paper discusses the aspect that the original strategy can be improved. For large scale eigenvalue problems that need a massively parallel treatment this aspect turns out to be nontrivial. The impact on the parallel performance will be shown by results of scaling experiments up to 1024 cores.

Influence of a channel bend on the purging of saline fluid from a cavity by an overflow of fresh water

A numerical and laboratory investigation on the purging of saline fluid from a cavity within a $60^\circ$~channel bend is presented to characterise the purging process in open channel bends. The numerical simulation uses a three dimensional, direct numerical simulation, fractional-step solver. The geometry replicates the laboratory experiment to define the mixing processes of a cavity with vertical sidewalls occupying the centre~$20^\circ$ of the $60^\circ$~channel bend. The secondary circulation as the flow moves through the bend increases the vertical momentum exchange within the cavity and hence destabilises the saline interface. References J. R. Anderson and A. K. Morrison. Environmental consequences of saline groundwater intrusion into the wimmera river, victoria. BMR. Journal of Australian Geology and Geophysics, 11:233--235, 1989d. S. Armfield and R. Street. An analysis and comparison of the time accuracy of fractional-step methods for the navier-stokes equations on staggered grids. International Journal for Numerical Methods in Fluids, 38(3):255--282, 2002. S. W. Armfield and W. Debler. Purging of density stabilized basins. International Journal of Heat and Mass Transfer, 36(2):519--530, January 1993. J. C. Bathurst, C. R. Thorne, and R. D. Hey. Secondary flow and shear stress at river bends. Journal of the Hydraulics Division, ASCE, 105 (HY10):1277---1295, 1979. H. Christie. Real-life management of an environmental water reserve, a wimmera perspective. In A.L. Wilson, R.L. Dehaan, R.J. Watts, K.J. Page, K.H. Bowmer, and A. Curtis, editors, Proceedings of the 5th Australian Stream Management Conference. Australian rivers: making a difference. Charles Sturt University, Thurgoona, New South Wales., 2007. W. Debler and S. W. Armfield. The purging of saline water from rectangular and trapezoidal cavities by an overflow of turbulent sweet water. Journal of Hydraulic Research, 35:43--62, 1997. P. H. Gaskell and A. K. C. Lau. Curvature-compensated convective transport: Smart, a new boundedness- preserving transport algorithm. International Journal for Numerical Methods in Fluids, 8(6):617--641, 1988. M. P. Kirkpatrick and S. W. Armfield. Experimental and large eddy simulation results for the purging of salt water from a cavity by an overflow of fresh water. International Journal of Heat and Mass Transfer, 48(2):341--359, January 2005. Henk A. van der Vorst. Iterative solution methods for certain sparse linear systems with a non-symmetric matrix arising from pde-problems. Journal of Computational Physics, 44(1):1--19, November 1981.

Bi-CGSTAB as an induced dimension reduction method

The Induced Dimension Reduction method [P. Wesseling, P. Sonneveld, Numerical experiments with a multiple grid- and a preconditioned Lanczos type method, in: Lecture Notes in Mathematics, vol. 771, Springer-Verlag, Berlin, 1980, pp. 543–562] was proposed in 1980 as an iterative method for solving large nonsymmetric linear systems of equations. IDR can be considered as the predecessor of methods like CGS (Conjugate Gradient Squared) [P. Sonneveld, CGS, a fast Lanczos-type solver for nonsymmetric linear systems, SIAM J. Sci. Statist. Comput. 10 (1989) 36–52] and Bi-CGSTAB (Bi-Conjugate Gradients STABilized [H.A. van der Vorst, Bi-CGSTAB: A fast and smoothly converging variant of Bi-CG for the solution of nonsymmetric linear systems, SIAM J. Sci. Statist. Comput. 13 (2) (1992) 631–644]). All three methods are based on efficient short recurrences. An important similarity between the methods is that they use orthogonalizations with respect to a fixed ‘shadow residual’. Of the three methods, Bi-CGSTAB has gained the most popularity, and is probably still the most widely used short recurrence method for solving nonsymmetric systems. Recently, Sonneveld and van Gijzen revived the interest for IDR. In [P. Sonneveld, M. van Gijzen, IDR( s): a family of simple and fast algorithms for solving large nonsymmetric systems of linear equations, Preprint, Delft Institute of Applied Mathematics, Delft University of Technology, Delft, The Netherlands, March 2007], they demonstrate that a higher dimensional shadow space, defined by the n × s matrix R ˜ 0 , can easily be incorporated into IDR, yielding a highly effective method. The original IDR method is closely related to Bi-CGSTAB. It is therefore natural to ask whether Bi-CGSTAB can be extended in a way similar to IDR. To answer this question we explore the relation between IDR and Bi-CGSTAB and use our findings to derive a variant of Bi-CGSTAB that uses a higher dimensional shadow space.

Special Issue on Accurate Solution of Eigenvalue Problems

The occasion for this special issue is the Sixth International Workshop on Accurate Solution of Eigenvalue Problems, which took place at The Pennsylvania State University from May 22–25, 2006. This special issue provides an outlet for papers from the workshop and recognizes advances in the numerical solution of eigenvalue and related problems. This is the second such special issue published in the SIAM Journal on Matrix Analysis and Applications; the first was published in number 4 of volume 28 in connection with the Fifth International Workshop on Accurate Solution of Eigenvalue Problems, which took place in Hagen, Germany, from June 29 to July 1, 2004. The twelve papers in the current issue are concerned with a variety of aspects that arise in the computation of eigenvalues and invariant subspaces: perturbation bounds and sensitivity, accuracy and convergence behavior of algorithms, exploitation of structure in matrices, and particular engineering applications. Thanks go to SIMAX Editor-in-Chief, Henk van der Vorst; guest editors Jesse Barlow, Froilán Dopico, and Zlatko Drmač, who put great effort into the careful and timely review of papers; and Mitch Chernoff, Cherie Trebisky, and other members of the SIAM staff who worked hard to publish this special issue.