bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear dynamic analysis of arch dams with joint sliding mechanism
Authors: Arabshahi Hamidreza , Lotfi Vahid 
Published: July 2009

PurposeThe purpose of this paper is to obtain an insight into the effects of sliding and/or joint opening at the contraction, perimeter and concrete lift joints on the nonlinear seismic response of arch dams.Design/methodology/approachThe seismic behavior of a typical thin double curvature arch dam is studied by a nonlinear finite element program developed by the authors. Joints are modeled with the use of zero thickness interface elements. Various constitutive relationships are implemented to account for sliding and opening along the joints. Effects of joint sliding parameters and foundation rock flexibility are also considered in the analyses.FindingsThe findings provide information about dynamic stress distribution through the dam body and stability of the dam as a whole and also the local stability of the most critical concrete blocks in the dam body.Practical implicationsUseful information for designing new arch dams or seismic evaluation of constructed dams.Originality/valueThis paper takes into account the stability of concrete blocks in the dam body as well as stability of the structure as a whole. Except for contraction joints, perimeter and concrete lift joints are also modeled. Practical as well as detailed models of sliding are provided for the analyses. The paper offers practical help to design and dam engineers.
A novel way of using fast wavelet transforms to solve dense linear systems arising from boundary element methods
Authors: Ebrahimnejad Latif , Attarnejad Reza 
Published: July 2009

PurposeThe purpose of this paper is to introduce a novel approach to solving linear systems arising from applying a Boundary Element Method (BEM) to elasticity problems.Design/methodology/approachThe key idea is based on using wavelet transforms as a tool to change dense and fully populated matrices of BEM systems into sparse matrices. Wavelets are then used again to produce an algorithm to solve the resultant sparse linear systems. The wavelet transformation part of the method can be added as a black box to existing BEM codes.FindingsNumerical results focusing on the sensitivity of the solution for various physical variables to the thresholding parameters, and savings in computer time and memory are presented. The results show that the proposed method is efficient for large problems.Research limitations/implicationsApplication of the proposed method is restricted to problems with number of DOF equal to an integer power of 2.Originality/valueThe novel algorithm to solve transformed algebraic linear equations uses NS‐form of the modified matrix, taking the advantage of the hierarchical nature of Multi‐Resolution Analysis (MRA) to decompose a parent system into descendant systems with reduced size. These smaller systems are then solved iteratively using generalized minimal residual method.
A new quadrilateral shell element using 16 degrees of freedom
Authors: Sabourin Francis , Carbonniere Jérôme , Brunet Michel 
Published: July 2009

PurposeThe purpose of this paper is to present a quadrilateral shell element using 16 degrees of freedom (dof) (12 translations and four rotations) which makes a pair with Morley's triangle at 12 dof. This latter has been updated by Batoz who later proposed an extension to a quadrilateral (“DKQ16”) but only with special interpolation functions for an elastic behaviour of the material. Precisely, it is in order to release from this strong limitation that a completely different formulation is proposed here.Design/methodology/approachThe development of this new quadrilateral called “DKS16” involves three stages. The first one starts from Morley's triangle updated by Batoz (“DKT12”) to derive a rotation‐free (RF) triangular element (“S3”). The second stage consists in generalising this triangle to a RF quadrilateral (“S4”). During the final leg, the S4 and DKT12 main features are combined to give the quadrilateral “DKS16”.FindingsOther parameters being equal, the type of finite element chosen for the forming stage simulation has a great influence on further springback result even in software with automatic remeshing. Particularly, it is pointed out that the RF shell elements S3 and S4 as well as the triangle DKT12 are less sensitive to the mesh size than classical shell elements with six dof per node. But, even if some improvements of in‐plane shear have been proposed, stamping codes users are reluctant to use triangles. That is why this paper presents an attempt to extrapolate a quadrilateral (DKS16) from the triangle DKT12 via S3 and S4 elements formulation. Numerous examples showing convergence and accuracy are presented: irregular meshes, large displacement analyses and deep‐drawing simulations.Practical implicationsThe triangular “S3” element is already implemented in RADIOSS® software and its implementation – as well as the one of “DKT12” – is in progress in Pam‐Stamp, both as “user elements”. The next step will be the implementation of the quadrilateral “S4” (RF) and, maybe, the element “DKS16” since both are cheaper in terms of computation time and are found interesting for sheet forming.Originality/valueIt seems obvious that curvatures are more exactly captured in RF elements (when nodes slide on die radius) since they are imposed in terms of translations instead of traditional nodal rotations not managed by contact conditions. As the neighbours are involved, a drawback of these RF elements is their complex formulation in case of branching surfaces and/or abrupt variations in material behaviour and/or thickness. This is not the case for elements such as DKT12 or DKS16, good candidates to add to the (long) list of cheap shell elements for large scale computations typical of sheet metal forming.
Parameter estimation for mechanical systems via an explicit representation of uncertainty
Authors: Blanchard Emmanuel , Sandu Adrian , Sandu Corina 
Published: July 2009

PurposeThe purpose of this paper is to propose a new computational approach for parameter estimation in the Bayesian framework.A posterioriprobability density functions are obtained using the polynomial chaos theory for propagating uncertainties through system dynamics. The new method has the advantage of being able to deal with large parametric uncertainties, non‐Gaussian probability densities and nonlinear dynamics.Design/methodology/approachThe maximum likelihood estimates are obtained by minimizing a cost function derived from the Bayesian theorem. Direct stochastic collocation is used as a less computationally expensive alternative to the traditional Galerkin approach to propagate the uncertainties through the system in the polynomial chaos framework.FindingsThe new approach is explained and is applied to very simple mechanical systems in order to illustrate how the Bayesian cost function can be affected by the noise level in the measurements, by undersampling, non‐identifiablily of the system, non‐observability and by excitation signals that are not rich enough. When the system is non‐identifiable and ana prioriknowledge of the parameter uncertainties is available, regularization techniques can still yield most likely values among the possible combinations of uncertain parameters resulting in the same time responses than the ones observed.Originality/valueThe polynomial chaos method has been shown to be considerably more efficient than Monte Carlo in the simulation of systems with a small number of uncertain parameters. This is believed to be the first time the polynomial chaos theory has been applied to Bayesian estimation.
Auditor tenure, auditor specialization, and information asymmetry
Authors: Almutairi Ali R. , Dunn Kimberly A. , Skantz Terrance 
Published: July 2009

PurposeThe purpose of this paper is to examine the relation between a company's bid‐ask spread, a proxy for information asymmetry, and auditor tenure and specialization.Design/methodology/approachThe tests use clustered regression for a sample of 31,689 company‐years from 1992 to 2001 and control for factors known to impact bid‐ask spread in cross‐section.FindingsThe findings suggest that the market's perception of disclosure quality is higher and private information search opportunities are fewer for companies engaging industry specialist auditors. In addition, the paper finds that information asymmetry has a U‐shaped relation to auditor tenure. This U‐shaped relation holds for both specialists and non‐specialists; however, the bid‐ask spread for specialists tends to fall below that of non‐specialists at all tenure intervals.Research limitations/implicationsThe findings may directly result from auditor tenure and specialization or it may be that those auditor‐related characteristics are a subset of concurrent choices made by the company that impacts disclosure quality.Practical implicationsCompanies have incentives to lower information asymmetry and the findings document that the choice of a specialist auditor and the length of the auditor relationship can potentially influence this objective.Originality/valueThe paper provides information to academics, regulators, companies, and auditors concerning the effect of auditor‐client relationships on the level of information asymmetry. In addition, it shows the importance of industry specialization and audit firm tenure on audit quality.
Culture and corporate voluntary reporting
Authors: Zaman Mir Monir , Chatterjee Bikram , Shiraz Rahaman Abu 
Published: July 2009

PurposeThe purpose of this paper is to explore the cultural underpinnings of accounting practices through a comparative analysis of India and New Zealand, using the chairperson's report, which is increasingly becoming one of the most important segments of the corporate annual report.Design/methodology/approachThe annual reports of Indian and New Zealand companies from 2001 to 2005 were selected to investigate the extent and nature of information disclosure in their chairperson's report. “Content analysis” is the main methodological orientation of the paper.FindingsThe paper argues that, contrary to propositions based on Hofstede's cultural framework, Indian companies provide more disclosure in their chairperson's report than their New Zealand counterparts. This leads to the conclusion that voluntary disclosure, more generally, is a complex phenomenon and cultural variables alone may not be sufficient predictors of the voluntary disclosure practices of a country.Originality/valueUsing India and New Zealand, two countries with significant cultural differences, according to Hofstede's typology, the paper extends the literature by focusing on the chairperson's report, a more recent accounting phenomenon which is gaining popularity across the globe.
Degradation of lac with storage and a simple method to check the same
Authors: Nath Goswami Dipendra , Prasad Niranjan , Baboo Bangali , Kishore Kumar Kaushal , Fahim Ansari Mohammad 
Published: July 2009

PurposeThe purpose of this paper is to find out a convenient chemical treatment for seedlac and shellac (semi‐refined and refined commercial forms of natural resin lac, respectively) for preventing degradation during storage at room temperature condition.Design/methodology/approachSeedlac and shellac are treated with a dilute solution of an antioxidant before storage. This method has not been attempted before. The changes in the physico‐chemical properties of both untreated and treated resins are investigated periodically during storage.FindingsAntioxidant delays the degradation of seedlac and shellac at least by six to eight months during the early period of storage. It is further observed that oxalic acid, used in the trade during conversion of seedlac into shellac by hot filtration for imparting gloss on shellac flakes for attracting buyers), causes rapid polymerisation of shellac resulting in zero value (100 percent decrease) of flow (fluidity) within 30 months of storage, whereas, shellac prepared without treatment of oxalic acid could be stored beyond that period without a significant deterioration in its qualities.Research limitations/implicationsAntioxidants are known to be scavengers of OH groups. Lac resin (shellac and seedlac) contains five hydroxyl groups and one carboxyl group. Thus, only one dilute concentration of antioxidant is used to avoid possible modification of seedlac and shellac.Practical implicationsConsumers of shellac are not aware of the ill effect of oxalic acid treatment being practiced by processors. The results obtained in the present study will help consumers to advise processors suitably before purchase and will be able to store shellac for a longer period if it is not treated with oxalic acid. The consumers may also use an antioxidant to delay degradation of seedlac/shellac.Originality/valueThe results obtained in this paper, regarding the effects of treatments of antioxidant and oxalic acid are not available in any previous publication. These are reported for the first time.
The anomalous effect of high intensity ultrasound on paper fibre‐filler combinations
Authors: Manning Andrew , Fricker Anna , Thompson Robert 
Published: July 2009

PurposeThe purpose of this paper is to explore the previously unreported phenomenon in which changes occur to the particle size distributions of calcium carbonate fillers, used in papermaking, when exposed to high intensity ultrasound.Design/methodology/approachCommercial paper pulps sonicated at a frequency of 20 kHz are found to produce aggregates of their mineral filler constituents. The effects of sonication on isolated long and short fibre, and ground and precipitated calcium carbonate filler systems are also investigated both with and without the presence of dispersants. The findings are supported by particle size analysis and scanning electron microscopy of the sonicated systems.FindingsIt is clearly shown that exposure to high intensity ultrasound induces filler aggregation. However, the effect only occurs when paper fibres and fillers coexist and is not apparent for suspensions of filler only or fibre only slurries. Furthermore, the treatment overrides the effect of dispersants used to keep filler in suspension during the manufacturing process. An accompanying fall in pH with increasing sonication times is also noted and is linked to these changes. It is proposed that radical species produced in the slurries during sonication may explain the observed phenomenon.Research limitations/implicationsThe role of pH is not clearly understood and needs further study.Practical implicationsThe findings may be of interest in paper manufacture where uniform dispersal of fillers throughout the pulp is of significant importance.Originality/valueThe phenomenon described in this paper has not previously been reported or explored. Further studies may add to knowledge of filler dispersions and their behaviour in papermaking.
Combretum bracteosum extracts as eco‐friendly corrosion inhibitor for mild steel in acidic medium
Authors: Okafor P.C. , Uwah I.E. , Ekerenam O.O. , Ekpe U.J. 
Published: July 2009

PurposeThe purpose of this paper is to investigate the corrosion inhibitive properties of extracts from mature leaves of Combretum bracteosum for the corrosion of mild steel in H2SO4.Design/methodology/approachAcid extracts from mature leaves of Combretum bracteosum are used as mild steel corrosion inhibitors in various tests at 30‐60°C. The gravimetric and hydrogen evolution (via the gasometric assembly) measurements are conducted.FindingsThe mature leaves of Combretum bracteosum extracts inhibit the corrosion of mild steel in H2SO4 to reasonable extent. Inhibition efficiency increases with the plant extracts concentration and decreases with temperature. Phenomenon of physical adsorption is proposed as the mechanism of inhibition and the Frumkin adsorption isotherm obeyed. Kinetic parameters for the dissolution of mild steel in H2SO4 solutions are calculated.Practical implicationsMature leaves extract from Combretum bracteosum can be used in chemical cleaning and pickling processes.Originality/valueThe research provides new information on the possible use of the leaves of Combretum bracteosum as an eco‐friendly corrosion inhibitor of mild steel in H2SO4.
Dyeing of cotton, wool and silk with extract of Allium cepa
Authors: Vankar Padma S. , Shanker Rakhi , Wijayapala Samudrika 
Published: July 2009

PurposeThe purpose of this paper is to evaluate the efficiency of dyeing on cotton wool and silk fabrics with natural dye obtained from kitchen waste of dry skin extract of Allium cepa.Design/methodology/approachThe dry skin of onion produces natural dye which has been used for dyeing textiles. In the present study, innovative dyeing with onion has been shown to give good dyeing results. Pretreatment with 2 per cent metal mordant and using 5 per cent of plant extract (owf) was found to be optimum and showed very good fastness properties for cotton, wool and silk dyed fabrics. For effective natural dyeing with dry skin extract of Allium cepa, conventional method of dyeing was carried out using metal mordants. The purpose of using this source was with an idea to produce value addition dyed product from kitchen waste as the dye has very good potential of uptake, adherence to the fabric and has good wash and light fastnesses. Results show very attractive hue colours.FindingsThe preference of using easily and cheaply available material for dyeing by conventional dyeing lowers the cost of natural dyeing and enhances resource productivity and as a result, reduces waste. This makes onion scale one of the easily available materials for natural dyeing industry.Research limitations/implicationsAlthough metal mordanting with copper sulphate and potassium dichromate are not ecofriendly but we have used only 2 per cent of these metal salts to prepare different shades with dry scales of Allium cepa extract.Practical implicationsThe method developed for natural dyeing of cotton, silk and wool fabrics using skin extract of allium in conjunction with metal mordanting has shown very deep coloration. The stepwise dyeing of cotton fabric with metal mordant by the natural dye Allium cepa showed that the stepwise dyeing process gave very good result. The dye uptake in case of stepwise dyeing was from 65‐68 per cent in the case of cotton, 70‐74 per cent in silk and 78‐82 per cent in wool with different mordants.Originality/valueThe method developed for natural dyeing of cotton, silk and wool fabrics using skin extract of allium in conjunction with metal mordanting has shown marked improvement in terms of dye adherence and fastness properties and can thus be recommended for industrial application.
Managing the process of an educational change
Authors: Wong Ping‐Man , Chi‐Keung Cheung Alan 
Published: July 2009

PurposeTo cope with the challenges of the twenty‐first century, the Hong Kong SAR government initiated the Curriculum Reform in 2001. In 2006, a research team from a tertiary institution was commissioned to review the progress of change for smooth implementation of the reform in its next phase. This paper aims to examine this issue.Design/methodology/approachThe nature of the review is basically a survey, applying questionnaires and follow‐up focus‐group interviews to collect data from different groups of subjects. The sample was around 20 per cent of the population, i.e. a total of 252 primary (n=138) and secondary (n=114) schools.FindingsThe paper reports findings on the support for the Reform by primary and secondary schools. Five areas of agreement among school heads are examined, which include challenges to be met, guiding principles of the reform, learning goals, reform framework and the overall agreement with the rationale of the reform. It is found that, while the curriculum reform was supported among school heads, senior teachers and teachers, there was a gap between the views of senior management team and frontier teachers.Research limitations/implicationsThis is a very comprehensive research project with a limited timeframe. The paper can only report and discuss findings mainly on the support for curriculum reform by school heads. Other aspects of the study will be discussed and reported separately in subsequent papers.Practical implicationsThe gap between the views of senior management team and frontier teachers is worth probing as this is the most obstructive factor to the implementation of the reform. Identifying the cause would be the first step in formulating strategies to address and, hopefully, to facilitate the smooth transition from the phase of implementation to the continuation phase of the change process.Originality/valueThe study has suggested the development of a two‐dimensional framework of agreement areas and stakeholders which will contribute to a better understanding of the change process in general, and achievements of a curriculum reform in particular. Other issues are also discussed.
Requirement engineering elicitation methods
Authors: Rouibah Kamel , Al‐Rafee Sulaiman 
Published: July 2009

PurposeThe purpose of this paper is to investigate the perceptions of 19 requirement engineering (RE) techniques in Kuwait in term of three criteria “awareness,” “use,” and “perceived value generated over past system development projects.” Also, this paper aims to examine possible relationships between these RE techniques and two information system development success factors.Design/methodology/approachThis paper develops a questionnaire and tests with a sample of respondents from 175 organizations in Kuwait.FindingsResults show that: Arab culture influence perception of RE techniques; most companies have good knowledge of different techniques; several different techniques for identifying and analyzing customer requirements are used; the most highly valued RE techniques are decision trees, goal oriented, prototyping, data flow diagram (DFD), and interviews; six techniques (tree analysis, role playing, unified modeling language, Kawakita Jiro method, flow charts, and Ishikawa) are found to have the least perceived value; and only two techniques (prototyping and decision tree) are highly correlated with the statement “Obtaining the right requirements is a critical success factor for system development,” while other three techniques (quality function deployment, DFD and role playing) are correlated with “We experienced problems during past system developments projects because of wrong requirements collection.”Research limitations/implicationsThe study sheds light on perceptions on RE techniques perception in Kuwait where less is known about the subject from Western researchers.Practical implicationsThis paper suggests re‐examining university curriculums in order to prepare students for familiarity with techniques that have proven their effectiveness elsewhere and call for more collaboration between academia and practitioners in order to appropriate research outcomes. In addition, this paper is of benefit to foreign consulting companies willing to penetrate the Gulf Cooperative Council.Originality/valueThis is the first Arab study that sheds light on system development practices in the Arab world.