Behnam Salimi and David R. Hayhurst
Purpose — The purpose of this paper is to seek improved solution techniques for combined boundary‐initial value problems (IVPs) associated with the time‐dependent creep…
Abstract
Purpose — The purpose of this paper is to seek improved solution techniques for combined boundary‐initial value problems (IVPs) associated with the time‐dependent creep deformation and rupture of engineering structures at high temperatures and hence to reconfigure a parallel iterative preconditioned conjugate gradient (PCG) solver and the DAMAGE XXX software, for 3‐D finite element creep continuum damage mechanics (CDM) analysis.Design/methodology/approach — The potential to speed up the computer numerical solution of the combined BV‐IVPs is addressed using parallel computers. Since the computational bottleneck is associated with the matrix solver, the parallelisation of a direct and an iterative solver has been studied. The creep deformation and rupture of a tension bar has been computed for a range of the number of degrees of freedom (ndf), and the performance of the two solvers is compared and assessed.Findings — The results show the superior scalability of the iterative solver compared to the direct solver, with larger speed‐ups gained by the PCG solver for higher degrees of freedom. Also, a new algorithm for the first trial solution of the PCG solver provides additional speed‐ups.Research limitations/implications — The results show that the ideal parallel speed‐up of the iterative solver of 16, relative to two processors, is achieved when using 32 processors for a mesh of ndf = 153,238. Originality/value — Techniques have been established in this paper for the parallelisation of CDM creep analysis software using an iterative equation solver. The significant computational speed‐ups achieved will enable the analysis of failures in weldments of industrial significance.
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Esmail Rezaei-Seresht, Aboulfazl Salimi and Behnam Mahdavi
The purpose of this paper is synthesis and evaluation of antioxidant and antibacterial activities of a series of new azo dyes derived from 4-aminostilbene.
Abstract
Purpose
The purpose of this paper is synthesis and evaluation of antioxidant and antibacterial activities of a series of new azo dyes derived from 4-aminostilbene.
Design/methodology/approach
First, the starting material 4-aminostilbene was prepared via two successive Wittig and reduction reactions from 4-nitrobenzyl bromide. The obtained 4-aminostilbene was then reacted with some phenols under the normal azo coupling reaction conditions to give five new azo products. Antioxidant activity of the azo compounds was determined by radical scavenging assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. Also, the antimicrobial activity of the compounds against one gram-positive and eight gram-negative strains was evaluated based on the inhibition zone using disc diffusion assay.
Findings
The structures of the azo dyes were identified and characterized by fourier-transform Infrared, 1H nuclear magnetic resonance (NMR) and ultraviolet-visible (UV-V) is spectroscopic methods. All the compounds showed higher antioxidant activity than ascorbic acid (Asc) and butylated hydroxytoluene (BHT) as positive controls. Moreover, the compounds showed lower antibacterial activity than the standard antibiotic vancomycin.
Research limitations/implications
Excellent antioxidant activity, along with antibacterial activity against Streptococcus pneumoniae and Pseudomonas aeruginosa, was observed for the two synthesized azo dyes.
Originality/value
Five novel azo dyes based on 4-aminostilbene were synthesized. The dyes have a highly p-extended conjugated structure comprising the phenolic and stilbenic segments, and they indicated good antioxidant activity, so that the two dyes (2c and 2d) even showed much more scavenging activity compared to BHT which is used as an antioxidant agent in food industries. These compounds with highest antioxidant activity also inhibited the growth of S. pneumoniae and P. aeruginosa.
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Giulio Mangano, Gabriel Castelblanco, Alberto De Marco and Filippo Maria Ottaviani
The influence of internal and external factors impacting the duration of the concession period in Public-Private Partnerships (PPPs) is essential for project outcomes considering…
Abstract
Purpose
The influence of internal and external factors impacting the duration of the concession period in Public-Private Partnerships (PPPs) is essential for project outcomes considering its implications on operational expenses, payback periods in project finance and long-term uncertainties. In this context, this research analyzes a set of key factors that may influence the duration of the concession period of PPP transport projects.
Design/methodology/approach
A triangulation approach combining both quantitative and qualitative methods was employed. This mixed-method approach incorporates an in-depth literature review to identify the factors that potentially affect the public sector decision on concession periods within transportation PPP programs. The information from all the transportation PPP projects (roads, ports, rails and airports) procured in 58 countries in Europe, Africa and Asia was retrieved from public databases, official records in each of the countries and academic papers. The information retrieved from each of the identified parameters was further examined through analysis of variance and linear regression to test the hypotheses.
Findings
Results demonstrate that user-pay PPPs should restrict minimum concession periods to prevent excessive user tariffs, which could result in societal resistance and potential long-term traffic underperformance. Additionally, PPP market’s willingness to accept longer concession periods depends on country’s risk profile and regulatory framework transparency. Conversely, high-risk countries may seek longer concession periods by utilizing payment mechanisms that allocate demand risk to the public sector.
Originality/value
This study provides relevant insights for better negotiating the concession duration to increase the value for money associated with the PPP project.
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Behnam Vahdani and Shayan Shahramfard
The purpose of this study is truck scheduling and assignment of trucks to the doors simultaneously since these issues were considered mainly separately in the previous research…
Abstract
Purpose
The purpose of this study is truck scheduling and assignment of trucks to the doors simultaneously since these issues were considered mainly separately in the previous research. Also, the door service time and its impact on truck scheduling were not taken into account, so this research endeavors to cover this gap.
Design/methodology/approach
In this research, a novel model has been presented for simultaneous truck scheduling and assignment problem with time window constraints for the arrival and departure of trucks, mixed service mode dock doors and truck queuing. To resolve the developed model, two meta-heuristic algorithms, namely, genetic and imperialist competitive algorithms, are presented.
Findings
The computational results indicate that the proposed framework leads to increased total costs, although it has a more accurate planning; moreover, these indicate that the proposed algorithms have different performances based on the criteria considered for the comparison.
Research limitations/implications
There are some limitations in this research, which can be considered by other researchers to expand the current study, among them the specifications of uncertainty about arrival times of inbound and outbound trucks, number of merchandises which has been loaded on inbound trucks are the main factors. If so, by considering this situation, a realistic scheme about planning of cross docking system would be acquired. Moreover, the capacity of temporary storage has been considered unlimited, so relaxing this limitation can prepare a real and suitable situation for further study. Examining the capacity in the front of each type of doors of cross-dock and executive servers are the other aspects, which could be expanded in the future.
Originality/value
In this study, a mathematical programing model proposed for truck scheduling to minimize total costs including holding, truck tardiness and waiting time for queue of trucks caused by the interference of each carrier’s movement. At the operational levels, this research considered a multi-door cross-docking problem with mixed service mode dock doors and time window constraints for arrival and departure time of trucks. Moreover, M/G/C queue system was developed for truck arrival and servicing of carriers to trucks.
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Maryam Kamaei and Petter Gottschalk
The purpose of this study is to compare women committing pink-collar and red-collar crimes in Iran. In the current study, the pink-collar crime, studying murder by women as…
Abstract
Purpose
The purpose of this study is to compare women committing pink-collar and red-collar crimes in Iran. In the current study, the pink-collar crime, studying murder by women as red-collar criminals and the root of “pink-collar crime” is considered the related terms.
Design/methodology/approach
Descriptive analytical method is used in this article.
Findings
It was previously thought that white-collar crime has no victim, and it is not necessary to imprison the criminal or consider other punishments. There is no recognized solution for such crimes, as opposed to the legislature and the government’s efforts, and therefore, consumers, government, employees, companies and executives cannot realize these crimes or be aware of them. Unfortunately, recognizing red-collar crimes is impossible using the old, outdated set of laws, and new laws are required. The phenomenon of white- and red-collar crime is endless and must always be in the attention of society to prevent its dangerous consequences for the community.
Originality/value
This article is original and has been submitted only to this journal and has not been submitted to another journal at the same time.
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Sundararaman Krishnamoorthi and Benny Raphael
The aim of this paper is to synthesize knowledge related to performance evaluation of automated construction processes during the planning and execution phases through a…
Abstract
Purpose
The aim of this paper is to synthesize knowledge related to performance evaluation of automated construction processes during the planning and execution phases through a theme-based literature classification. The primary research question that is addressed is “How to quantify the performance improvement in automated construction processes?”
Design/methodology/approach
A systematic literature review of papers on automated construction was conducted involving three stages-planning, conducting and reporting. In the planning stage, the purpose of the review is established through key research questions. Then, a four-step process is employed consisting of identification, screening, shortlisting and inclusion of papers. For reporting, observations were critically analysed and categorized according to themes.
Findings
The primary conclusion from this study is that the effectiveness of construction processes can only be benchmarked using realistic simulations. Simulations help to pinpoint the root causes of success or failure of projects that are either already completed or under execution. In automated construction, there are many complex interactions between humans and machines; therefore, detailed simulation models are needed for accurate predictions. One key requirement for simulation is the calibration of the models using real data from construction sites.
Research limitations/implications
This study is based on a review of 169 papers from a database of peer-reviewed journals, within a time span of 50 years.
Originality/value
Gap in research in the area of performance evaluation of automated construction is brought out. The importance of simulation models calibrated with on-site data within a methodology for performance evaluation is highlighted.