The Distributed Assembly Permutation Flowshop Scheduling Problem

Nowadays, improving the management of complex supply chains is a key to become competitive in the twenty-first century global market. Supply chains are composed of multi-plant facilities that must be coordinated and synchronised to cut waste and lead times. This paper proposes a Distributed Assembly Permutation Flowshop Scheduling Problem (DAPFSP) with two stages to model and study complex supply chains. This problem is a generalisation of the Distributed Permutation Flowshop Scheduling Problem (DPFSP). The first stage of the DAPFSP is composed of f identical production factories. Each one is a flowshop that produces jobs to be assembled into final products in a second assembly stage. The objective is to minimise the makespan. We present first a Mixed Integer Linear Programming model (MILP). Three constructive algorithms are proposed. Finally, a Variable Neighbourhood Descent (VND) algorithm has been designed and tested by a comprehensive ANOVA statistical analysis. The results show that the VND algorithm offers good performance to solve this scheduling problem.     

Numerical study of film cooling effectiveness of a gas turbine blade under variable blowing ratio and turbulence intensity

The present paper investigates a three-dimensional simulation of film cooling on a C3X turbine blade with a single hole at a suction surface. The Reynolds averaged Navier–Stokes approach with k–ε realizable turbulence model and enhanced wall function are used for the numerical simulation. To simulate the jet flows, the length of the jet input approximately 4.5 times the diameter of the hole is added to the geometry so that the jet outlet flow is closer to the actual condition. The density ratio of the cooling flow to the mainstream flow is assumed about 2. The numerical results in four blowing ratios of 0.5, 0.7, 1.0, and 1.4, and at the low turbulence intensity (0.02%), and high turbulence intensity (12%) are extracted and compared for the turbine blade with a single hole. The results show that the turbulence intensity has a dual effect on the film cooling effectiveness and a higher blowing ratio increases the strength of the jet against the cross-flow. Moreover, it is illustrated that the distribution of the film cooling effectiveness in higher blowing ratios and high turbulence intensity is more uniform than the low blowing ratios and low turbulence intensity.     

Viscosity of pure carbon dioxide at supercritical region: Measurement and correlation approach

In this paper a method to calculate the viscosity of supercritical CO2 is introduced. A rolling body viscometer equipped with a gas booster was used. Based on new experimental and available data, a new correlation is developed. The proposed correlation is valid in temperature range from 310 K to 900 K. Moreover, the model predictions are acceptable in pressures between 7.5 and 101.4 MPa. The model superiority over other conventional methods has been demonstrated.     

Quality assessment of electrohydrodynamic and microwave dehydrated banana slices

In contrast to the inherently energy-efficient electrohydrodynamic (EHD) methods, conventional drying methods are energy intensive. In the present study, comparisons were made between banana slice samples dried by high-voltage-DC powered multiple-point-to-plate electrodes and those dried by microwave (MW). For this purpose, banana slices were dried by an EHD drying system at electric field strengths of 6, 8, and 10 kV/cm and by an MW drying system at specific power levels of 9 and 18 W/g. No constant rate period was observed in the EHD; hence, the entire drying process occurred in the falling rate period, whereas the drying rates of MW-dried samples occurred at a constant rate and during the falling rate periods. Analysis of variance showed that drying method had a significant effect on drying time, rehydration ability, shrinkage, color parameters (L^∗, a^∗, b^∗, and ΔE), and consumed energy. The mean values of specific consumed energy for EHD and MW drying methods were 0.34 and 9.66 kJ/g, respectively. In terms of drying time, EHD was not fast; however, its advantages of less energy requirement and great product quality including lower shrinkage, great rehydration ability, and better appearance make it a good choice for drying banana slices.     

Role of bazaars as a unifying factor in traditional cities of Iran: The Isfahan bazaar

A city is a vital organism that lives and grows like other organisms. Therefore, implementing development plans that would provide a sense of unity and integration in relation to the city as a whole is necessary. Traditional Iranian architecture is full of samples evolved during the course of Iranian history that can serve as architectural paragons of the city. In Iran's traditional cities, a sense of unity exists in various urban areas. The traditional city of Isfahan is one of the most valuable samples and was selected as the case study in this research. Accordingly, the most important questions of this research are as follows: (1) What is the role of bazaars in creating a sense of unity in the traditional cities of Iran? (2) How do bazaars play out their role in the integration of these cities? This research focuses on the concept of a “traditional city” to determine the role of bazaars in such cities. The results show that bazaars are crucial in giving a sense of integrity to the concept of a traditional Iranian city. Bazaars provide cohesion among the different parts of cities, such as residential areas, as well as socio-political and trade centers. This condition means that traditional bazaars play two important roles in traditional cities: (1) they interconnect the different parts of the city's physical structure; and (2) the crucial role of bazaars in a city's social and cultural structure brings about unity among the citizens in the city. Bazaars as a unifying element connect the main urban functions and guarantee the city's economic and social life.     

High-Temperature Oxidation Behavior of Nano-structured CoNiCrAlY–YSZ Coatings Produced by HVOF Thermal Spray Technique

In this study the effects of adding yttria-stabilized zirconia (YSZ) reinforcement by mechanical milling method on the oxidation resistance of CoNiCrAlY coatings were investigated. For this purpose 0, 5, 10 and 15% YSZ were mixed with the commercial CoNiCrAlY powder and mechanically milled for 24 h in argon atmosphere. The high-velocity oxygen-fuel method was used for deposition of composite and commercial powders on Inconel 617 substrate. Both commercial and nano-structured coatings were oxidized at 1000 °C for 100 h. Scanning electron microscopy together with energy-dispersive spectroscopy and X-ray diffraction analysis were used for analyzing the oxide scales formed on the coatings surface after oxidation process. The results showed that the porosity of nano-structured coatings was higher than that of the commercial coating, which was related to an undesirable morphology of the feedstock powders. The relatively high porosity of the nano-structured coatings caused the diffusion rate of oxygen into the coatings to be accelerated. On the other hand, a high Al supply due to a large amount of grain boundaries in nano-structured coatings facilitated the formation of an Al₂O₃ layer on coating’s surface. The undesirable oxidation of splats in nano-structured coatings during spraying resulted in an increased oxidation rate of the coatings.     

Flavonoids profile and antioxidant activity in flowers and leaves of hawthorn species (Crataegus spp.) from different regions of Iran

This study was undertaken to determine the total quantity of phenolic and flavonoids, as well as to find out about the HPLC quantification of some individual phenolic compounds (i.e. chlorogenic acid, vitexin 2”-O-rhamnoside, vitexin, rutin, hyperoside, quercetin, and isoquercetin) in flowers and leaves of 56 samples of different hawthorn species (Crataegus spp.) collected from different geographical regions of Iran. The amount of total phenolics ranges from 7.21 to 87.73 mg GAE/g in dry weight of the plant, and the total amount of flavonoids varied amongst species and in different plant organs ranging from 2.27 to 17.40 mg/g dry weight. Chlorogenic acid, vitexin, and vitexin 2”-O-rhamnoside were found to be the most abundant phenolic compounds in the extracts of hawthorn leaves. Meanwhile, chlorogenic acid, hyperoside, and rutin were the most abundant phenolic compounds in the extracts of hawthorn flowers in most genotypes. The antioxidant activity widely varied in species and in different organs of each individual plant, ranging from 0.9 to 4.65 mmol Fe⁺⁺/g DW plant, calculated through the ferric-reducing antioxidant power (FRAP) method. Thus, this could provide valuable data for developing breeding strategies and plans; it can also help us in selecting genotypes with high phenolic contents for producing natural antioxidants and other bioactive compounds beneficial for food or the pharmaceutical industries.     

Bag of recurrence patterns representation for time-series classification

Pattern Analysis and Applications - Time-series classification (TSC) has attracted a lot of attention in pattern recognition, because wide range of applications from different domains such as...     

Shaking table performance of reinforced soil retaining walls with different facing configurations

In this paper, a new type of MSE wall facing, termed as hybrid facing, is introduced and studied, which is built using a combination of concrete modular blocks and cast-in-place concrete. Two shaking table tests were carried out to compare seismic performances of model reinforced soil retaining walls with full-height vs. hybrid facing configurations. Results of this study show that the stability and performance of the hybrid facing model were similar to those of the full-height panel wall for peak input acceleration magnitudes less than 0.40 g. The amplification factors along the height of the facing were more uniform and smaller in the hybrid facing model as compared to the full-height panel wall, especially at higher peak acceleration amplitudes. Dynamic increment of lateral earth loads acting on the facing in both cases were found to be only 20% of the values calculated using pseudo-static methods. Connection loads in the hybrid facing model were smaller than those in the full-height panel wall, which was attributed to its smaller facing displacements.