Liming Xiao, Bin Han, Sainan Yang and Shuai Liu
The construction of industrial park in the current development model of circular economy has been widely regarded as one of the important modes of macroeconomic exploration all…
Abstract
The construction of industrial park in the current development model of circular economy has been widely regarded as one of the important modes of macroeconomic exploration all over the world. Therefore, the research on the application of multi-project management theory based on circular economy in the construction of industrial park was proposed in this paper. First, the circular economy and multi-project management theory were expounded in detail. Then, the geographical location of multi project management in Qingyuan recycled plastic industrial park in Guangdong Province and the distribution of each building community were explained. And on this basis, the construction of the park's production, plant areas, residential areas and the planning objectives after completion were analyzed in detail. On the basis of analysis, the multi project management model used in the park was explained. It is pointed out that the construction of the park should be based on its own planning and practical needs, and the appropriate multi project management model should be chosen.
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Zimou Tang, Min Yang, Jianxiong Xiao, Zheng Shen, Liming Tang and Jibin Wang
This paper aims to present an engineering computational method for fatigue life evaluation of welded structures on large-scale equipment under random vibration load.
Abstract
Purpose
This paper aims to present an engineering computational method for fatigue life evaluation of welded structures on large-scale equipment under random vibration load.
Design/methodology/approach
Based on a case study of the traction transformers, virtual fatigue test (VFT) was proposed via numerical simulation approach. Static analysis was conducted to identify the risky zone and then dynamic response of the risky welds under random vibration load was calculated based on frequency-domain structural stress method (FDSSM) theory, life distribution and associated survivability at various locations of the structure were obtained. Structural modification was finally performed according to the evaluation results. Moreover, experimental test was carried out and compared with the virtual test result.
Findings
By applying the virtual test, fatigue life of the complex welded structures on large-scale equipment can be accurately and efficiently obtained considering dynamic effect under random vibration load. Meanwhile, risky welds can be directly determined and targeted modification scheme can be accordingly concluded. Validity of the VFT result was proved by comparing with the experimental test.
Originality/value
The proposed method can help obtain equivalent structural stress and fatigue life distribution of the welded structure at any position with various survivability and make quantitative evaluation on the life-extending effect of the structural modification. This method shows significant cost and efficiency advantages over experimental test during design stage of the large-scale structures in numerous manufacturing industries.
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Liming Yao, Yuhong Shuai, Xudong Chen and Anran Xiao
Due to recent technological advances, the retail industry has changed significantly. This paper examines a novel unmanned retail mode-unattended convenience store to identify the…
Abstract
Purpose
Due to recent technological advances, the retail industry has changed significantly. This paper examines a novel unmanned retail mode-unattended convenience store to identify the possible operational problems and develop appropriate managerial recommendations.
Design/methodology/approach
A data-driven two-stage epsilon-based measure (EBM) data envelopment analysis (DEA) method was developed to evaluate operational performance data from 33 unattended convenience stores and assess the impacts on efficiency of the internal factors, and a Tobit regression analysis was employed to examine the external environment.
Findings
It was found that the overall economic performances were relatively low and fluctuated significantly; however, the social performances were slightly higher. The out-of-stock rate was found to have a negative impact on efficiency, and regional characteristics were found to have significant effects on performance.
Practical implications
This study sought to identify current operational problems with unattended convenience stores to provide managerial insights. The cross-sectional assessment suggested that to achieve better performance, particular attention needed to be paid to store locations and surrounding store environments.
Originality/value
First, this paper establishes a novel theoretical framework to evaluate the economic and social operational performances at unattended convenience stores. Second, it contributes to research on unattended convenience stores and the unmanned retail industry and offers significant guidance on detecting operational deficiencies and improving future performances.
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Liming Zhai, Yongyao Luo, Xin Liu, Funan Chen, Yexiang Xiao and Zhengwei Wang
The purpose of this paper is to analyze lubrication characteristics of a tilting pad thrust bearing considering the effect of the thermal elastic deformation of the pad and collar.
Abstract
Purpose
The purpose of this paper is to analyze lubrication characteristics of a tilting pad thrust bearing considering the effect of the thermal elastic deformation of the pad and collar.
Design/methodology/approach
This study used the fluid–solid interaction (FSI) technique to investigate the lubrication characteristics of a tilting pad thrust bearing for several typical operating conditions. The influences of the rotational speed, the thrust load and the oil supply temperature on the lubrication characteristics were analyzed.
Findings
The three-dimensional (3D) film model clearly shows that there is no pressure gradient but large temperature gradients across the film thickness. The wall heat transfer coefficients on the pad surfaces distribute in a very complex way and change within a large range. The rotational speed, the thrust load and the oil supply temperature have great but different influences on the lubrication characteristics.
Originality/value
This paper has preliminarily revealed the lubrication mechanism of the tilting-pad thrust bearings. The 3D FSI method is suggested to evaluate the thermal-elastic-hydrodynamic deformations of thrust bearings instead of the conventional method which iteratively solves the Reynolds equation, the energy equation, the heat conduction equation and the elastic equilibrium equation. Using FSI method, the heat transfer coefficients on the pad surfaces can be evaluated better.
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O.R. Batic, J.D. Sota, J.L. Fernández, N. Bellotti and R. Romagnoli
This research aims to study the influence of limestone filler on rebar corrosion.
Abstract
Purpose
This research aims to study the influence of limestone filler on rebar corrosion.
Design/methodology/approach
Mortar samples containing 35% calcareous filler and with a rebar inserted in the axis, were cast. Specimens were cured at the open air and during 28 days in lime water. After curing, they were submerged in two electrolytes (tap water and 3% NaCl) and corrosion parameters (corrosion potential and corrosion current) were monitored over time by d.c. techniques. Simultaneously, electrochemical noise measurements were carried out. After corrosion tests, rebars were pulled out by lateral compression, and their surface observed by scanning electron microscopy.
Findings
In general, carbonate additions impaired mortar protective properties, especially in the presence of chloride and changed the nature of the protective layer on rebars. The curing process did not introduce significant differences except for mortars with a high water cement ratio cured in lime water for which the beneficial effects of the simultaneous presence of carbonate and lime in the pore solution could be appreciated. The role of carbonate additions is to provide carbonate anions to passivate rebars. This passivation process caused corrosion rates not to be so high. Carbonate anions also deposited on oxide spots which were rendered passive but this process was not uniform. Certain areas on the rebar underwent intense carbonation while others showed increased corrosion rates.
Originality/value
There are not many corrosion studies about the influence of limestone filler on rebars corrosion. Particularly, this paper deals with mortars containing high percentages of carbonate additions. Results showed that the presence of this type of admixture changes the structure of the passive layer and, sometimes, may increase corrosion rates.
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Shivendra Singh Rathore and Chakradhara Rao Meesala
The purpose of this paper is to investigate the effect of the replacement of natural coarse aggregate (NCA) with different percentages of recycled coarse aggregate (RCA) on…
Abstract
Purpose
The purpose of this paper is to investigate the effect of the replacement of natural coarse aggregate (NCA) with different percentages of recycled coarse aggregate (RCA) on properties of low calcium fly ash (FA)-based geopolymer concrete (GPC) cured at oven temperature. Further, this paper aims to study the effect of partial replacement of FA by ground granulated blast slag (GGBS) in GPC made with both NCA and RCA cured under ambient temperature curing.
Design/methodology/approach
M25 grade of ordinary Portland cement (OPC) concrete was designed according to IS: 10262-2019 with 100% NCA as control concrete. Since no standard guidelines are available in the literature for GPC, the same mix proportion was adopted for the GPC by replacing the OPC with 100% FA and W/C ratio by alkalinity/binder ratio. All FA-based GPC mixes were prepared with 12 M of sodium hydroxide (NaOH) and an alkalinity ratio, i.e. sodium hydroxide to sodium silicate (NaOH:Na2SiO3) of 1:1.5, subjected to 90°C temperature for 48 h of curing. The NCA were replaced with 50% and 100% RCA in both OPC and GPC mixes. Further, FA was partially replaced with 15% GGBS in GPC made with the above percentages of NCA and RCA, and they were given ambient temperature curing with the same molarity of NaOH and alkalinity ratio.
Findings
The workability, compressive strength, split tensile strength, flexural strength, water absorption, density, volume of voids and rebound hammer value of all the mixes were studied. Further, the relationship between compressive strength and other mechanical properties of GPC mixes were established and compared with the well-established relationships available for conventional concrete. From the experimental results, it is found that the compressive strength of GPC under ambient curing condition at 28 days with 100% NCA, 50% RCA and 100% RCA were, respectively, 14.8%, 12.85% and 17.76% higher than those of OPC concrete. Further, it is found that 85% FA and 15% GGBS-based GPC with RCA under ambient curing shown superior performance than OPC concrete and FA-based GPC cured under oven curing.
Research limitations/implications
The scope of the present paper is limited to replace the FA by 15% GGBS. Further, only 50% and 100% RCA are used in place of natural aggregate. However, in future study, the replacement of FA by different amounts of GGBS (20%, 25%, 30% and 35%) may be tried to decide the optimum utilisation of GGBS so that the applications of GPC can be widely used in cast in situ applications, i.e. under ambient curing condition. Further, in the present study, the natural aggregate is replaced with only 50% and 100% RCA in GPC. However, further investigations may be carried out by considering different percentages between 50 and 100 with the optimum compositions of FA and GGBS to enhance the use of RCA in GPC applications. The present study is further limited to only the mechanical properties and a few other properties of GPC. For wider use of GPC under ambient curing conditions, the structural performance of GPC needs to be understood. Therefore, the structural performance of GPC subjected to different loadings under ambient curing with RCA to be investigated in future study.
Originality/value
The replacement percentage of natural aggregate by RCA may be further enhanced to 50% in GPC under ambient curing condition without compromising on the mechanical properties of concrete. This may be a good alternative for OPC and natural aggregate to reduce pollution and leads sustainability in the construction.
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Nausheen Bibi Jaffur, Pratima Jeetah and Gopalakrishnan Kumar
The increasing accumulation of synthetic plastic waste in oceans and landfills, along with the depletion of non-renewable fossil-based resources, has sparked environmental…
Abstract
The increasing accumulation of synthetic plastic waste in oceans and landfills, along with the depletion of non-renewable fossil-based resources, has sparked environmental concerns and prompted the search for environmentally friendly alternatives. Biodegradable plastics derived from lignocellulosic materials are emerging as substitutes for synthetic plastics, offering significant potential to reduce landfill stress and minimise environmental impacts. This study highlights a sustainable and cost-effective solution by utilising agricultural residues and invasive plant materials as carbon substrates for the production of biopolymers, particularly polyhydroxybutyrate (PHB), through microbiological processes. Locally sourced residual materials were preferred to reduce transportation costs and ensure accessibility. The selection of suitable residue streams was based on various criteria, including strength properties, cellulose content, low ash and lignin content, affordability, non-toxicity, biocompatibility, shelf-life, mechanical and physical properties, short maturation period, antibacterial properties and compatibility with global food security. Life cycle assessments confirm that PHB dramatically lowers CO2 emissions compared to traditional plastics, while the growing use of lignocellulosic biomass in biopolymeric applications offers renewable and readily available resources. Governments worldwide are increasingly inclined to develop comprehensive bioeconomy policies and specialised bioplastics initiatives, driven by customer acceptability and the rising demand for environmentally friendly solutions. The implications of climate change, price volatility in fossil materials, and the imperative to reduce dependence on fossil resources further contribute to the desirability of biopolymers. The study involves fermentation, turbidity measurements, extraction and purification of PHB, and the manufacturing and testing of composite biopolymers using various physical, mechanical and chemical tests.
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Saadia Saadi, Mebarek Djebabra and Wafa Boulagouas
The purpose of this paper is to evaluate the environmental risks of the worn-water discharges of an Algerian tannery.
Abstract
Purpose
The purpose of this paper is to evaluate the environmental risks of the worn-water discharges of an Algerian tannery.
Design/methodology/approach
It consists of a proposal for a combined methods based on the simultaneous use of the environmental structured analysis and design techniques and environmental failure mode and effect analysis (EFMEA).
Findings
In the contribution, the authors insist on the complementarity between these two methods to the identification and measurement of the environmental parameters of an Algerian tannery. The identified environmental impacts were prioritized on the environmental priority number combined with the improvement possibility (F).
Research limitations/implications
The contribution makes it possible to deduce the environmental aspects and, consequently, to emphasize the contribution of the environmental risk assessment on the environmental performance evaluation.
Practical implications
The contribution constitutes an invaluable help to the implementation of environmental performance evaluation process.
Originality/value
The employing coupled structured analysis and technical design and EFMEA methods have remarkably reduced the significance of the environmental impacts of an Algerian tannery.
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Daniel Paul Thanaraj, Anand N. and Prince Arulraj
This paper aims to explain the influence of Standard Fire as per ISO 834 on the strength and microstructure properties of concrete specimens with different strength grade.
Abstract
Purpose
This paper aims to explain the influence of Standard Fire as per ISO 834 on the strength and microstructure properties of concrete specimens with different strength grade.
Design/methodology/approach
The strength grades of concrete considered for the experimental investigation were Fck20, Fck30, Fck40 and Fck50. The specimens were heated up to 1, 2, 3 and 4 h as per standard fire curve. Effect of elevated temperature on compressive and flexural behavior of specimens with various strength grades was examined. Effects of age of concrete, weight loss, surface characteristics and thermal crack pattern were also investigated.
Findings
Experimental investigation shows that strength grade, duration of exposure and age of concrete are the key parameters affecting the residual strength of concrete. For the beams exposed to 3 and 4 h of heating, the residual flexural strength was found to be so insignificant that the specimens were not able to even sustain their own weight. The loss in compressive and flexural strength of Fck50 concrete specimens heated up to 1 h were found to be 26.41 and 86.03 per cent of the original unheated concrete, respectively. The weight loss was found to be more for higher grade concrete specimens, and it was about 8.38 per cent for Fck50 concrete. Regression analysis was carried out to establish the empirical relation between residual strength and grade of concrete. Scanning electron microscopy and thermogravimetric analysis were carried out to examine the damage level of fire-affected concrete specimens.
Originality/value
Empirical relationship was developed to determine the residual strength of concrete exposed to elevate temperature, and this will be useful for design applications. This database may be useful for identifying member strength of reinforced beams subjected to various durations of heating so that suitable repair technique can be adopted from the available database. It will be useful to identify the proper grade of concrete with regard to fire endurance, in the case of concrete under compression or flexure.
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For the islands of the Caribbean, tourism is more than an industry to be managed. Significantly, it is a socioeconomic phenomenon that if managed effectively can address some of…
Abstract
For the islands of the Caribbean, tourism is more than an industry to be managed. Significantly, it is a socioeconomic phenomenon that if managed effectively can address some of the challenges facing the region. Tourism higher education plays a critical role in preparing graduates to shape an improved Caribbean tourism society and in performing research. Over the years, its tourism education has been framed by “Western models” that have not taken sufficient account of the Caribbean reality. The focus of this chapter is to define Caribbean education and to propose a tourism higher education strategy for the implementation in part of this education.