A simultaneous planning of production and scheduling operations in flexible flow shops: case study of tile industry

The aim of this paper is to study a simultaneous lot-sizing and scheduling in multi-product, multi-period flexible flow shop environments. A new mixed integer programming (MIP) model is proposed to formulate the problem. The objective function includes the total cost of production, inventory, and external supply. In this study, in case of not meeting the demand of customers, this demand should be met by foreign suppliers in higher price. Due to the high computational complexity of the studied problem, a rolling horizon heuristic (RHH) and particle swarm optimization algorithm (PSO) are implemented to solve the problem. These algorithms find a feasible and near-optimal from production planning and scheduling. Additionally, Taguchi method is conducted to calibrate the parameters of the PSO algorithm and select the optimal levels of the influential factors. The computational results show that the algorithms are capable of achieving results with good quality in a reasonable time and PSO has better objective values in comparison with RHH. Also, the real case study for tile industry with real features is applied. Sensitivity analysis is used to evaluate the performance of the model.     

Graphene network enabled high speed electrical actuation of shape memory nanocomposite based on poly(vinyl acetate)

Here strong electroactive shape memory nanocomposites were prepared by incorporating graphene nanoplatelets into poly(vinyl acetate) (PVAc ) through the simple solvent mixing method. TEM and XRD revealed that well exfoliated graphene nanoplatelets formed a continuous network throughout the matrix with a large amount of interconnectedness. Dynamic mechanical analysis showed that the inclusion of graphene significantly improves both glassy and rubbery moduli of the matrix. Furthermore, the prepared nanocomposites demonstrated a marked electrical conductivity up to 24.7 S m^?1 and thereby surprisingly rapid electrical actuation behaviour exhibiting a 100% recovery ratio in 2.5 s. Moreover, PVAc and its nanocomposites displayed scratch self‐healing capability. This work demonstrates that the PVAc /graphene nanocomposites with high modulus and excellent electroactive shape memory performance can be a promising material in many applications such as sensors and fast deployable and actuating devices. © 2016 Society of Chemical Industry     

Hydrometallurgical Extraction of Vanadium from Mechanically Milled Oil-Fired Fly Ash: Analytical Process Optimization by Using Taguchi Design Method

In this study, the Taguchi design method was employed to determine the optimum experimental parameters in extraction of vanadium by NaOH leaching of oil-fired fly. Prior to designed experiments, the raw precipitates were mechanicallly milled using a high-energy planetary ball mill. Experimental parameters were investigated as follows: mechanical milling (MM) times (2 and 5?hours), NaOH (1 and 2 molar concentration) as reaction solution (RS), powder to solution (P/S) ratios (100/400 and 100/600?mg/mL), temperature (T) of reaction system (303 K and 333?K [30?°C and 60?°C]), stirring times (ST) of reaction media (4 and 12?hours), stirring speed (SS) being adjusted to 400 and 600?rpm, and rinsing times (RT) of remained filtrates (1 and 3?hours). Statistical analysis of signal-to-noise ratio followed by analysis of variance was performed in order to estimate the optimum levels and their relative contributions. Data analysis is carried out using L₈ orthogonal array consisting of seven parameters each with two levels. The optimum conditions were MM1 (3?hours), RS2 (2 molar NaOH), P/S2 (100/600?mg/mL), T2 (333?K [60?°C]), ST2 (12?hours), SS1 (400?rpm), and RT1 (1?hour). Finally, from environmental and economical points of view, the process is faster and better organized by employing this analytical design method.     

Transmission pricing and recovery of investment costs in the deregulated power system based on optimal circuit prices

Transmission pricing has become a major issue in the discussions about the deregulated electricity markets.Conse-quently,open access to the transmission system is one of the basic topics to allow compe...     

Evaluation of Centrifugal Casting Process Parameters for In Situ Fabricated Functionally Gradient Fe-TiC Composite

A gradient Fe-TiC composite was successfully produced via combination of in situ reaction with centrifugal casting techniques. Additionally, some of the effective parameters of the centrifugal casting process have been studied. Cast iron and ferrotitanium, which were used as raw materials, were melted using a high-frequency induction furnace coupled with centrifugal equipment. The microstructure and phase characterization of the fabricated composite was studied by scanning electron microscopy, optical microscopy, and X-ray diffraction. The results show that the production of a pearlite matrix composite reinforced by TiC particles is feasible. The distribution of TiC in the pearlitic matrix is completely uneven as a result of density difference between molten medium and TiC in the centrifugal casting process.     

Cavity Control of Prefoldin Nano Actuator (PNA) by Temperature and pH

Nano-Micro Letters - A molecular dynamics study to investigate the cavity control of Prefoldin based bio nano actuator is presented in this paper. Prefoldin is a molecular chaperone with a...     

Energy production trend in Iran and its effect on sustainable development

The purpose of this study is to review the energy production trend from different energy resources in recent decades and its effect on sustainable energy production as one of the basic axis of sustainable development in Iran.Ninety nine percent of energy production in Iran comes from oil & gas and only 1% from renewable energy resources. Since Iran has very rich fossil energy resources, little attention has been paid to explore alternative ways of energy production. Majority of country's income is from oil & gas which put extra pressure on its natural resources. Continuing with the existing trend may lead to a path away from the goals of sustainable development, set for the country. Therefore, the sustainability study should be of interest to decision-makers.     

Optimizing the mechanical and physical properties of thermoplastic starch via tuning the molecular microstructure through co‐plasticization by sorbitol and glycerol

Nowadays, environmental hazards caused by plastic wastes are a major concern in academia and industry. Utilization of biodegradable polymers derived from renewable sources for replacing common petroleum‐based plastics is a potential solution for reducing the problem. In this regard, starch has become one of the most promising alternatives to non‐biodegradable polymers for depleting plastic waste thanks to its low expense, abundance, renewability and biodegradability. However, the main drawbacks of starch are its poor processability, weak mechanical properties and severe hydrophilicity. In this work, thermoplastic starch (TPS) samples have been prepared using glycerol and sorbitol as co‐plasticizers in a laboratory co‐rotating twin screw extruder. Based on the mechanical test results, glycerol caused higher elongation to break but had lower tensile strength and elastic modulus compared to sorbitol plasticized starch. Fourier transform infrared spectroscopy and DSC results indicated that the hydrogen bond interaction between starch chains and plasticizers could be improved by replacing glycerol by sorbitol, which resulted in higher resistance against retrogradation proved by XRD results. TGA illustrated that the higher the sorbitol to glycerol ratio was, the more stable was the TPS. Using a proper amount of plasticizers (42 wt% total plasticizer, sorbitol to glycerol ratio 2:1) led to the preparation of a TPS sample with optimized properties including enhanced mechanical properties, high thermal stability, strong hydrogen bond formation and high resistance against retrogradation. © 2017 Society of Chemical Industry