Multi-objective,multi-period location-routing model to distribute relief after earthquake by considering emergency roadway repair

Natural disasters such as earthquakes impose destructive effects in the form of human injuries and damage to properties each year. Damage caused by the earthquake can disrupt traffic and highway systems, block vehicles and relief operations and make distribution operations difficult. Therefore, the repair of damaged roads in the least possible time so that distribution of relief can be done is a significant natural phenomenon after the disaster. In this study, a new mathematical integer nonlinear multi-objective, multi-period, multi-commodity model is suggested to locate the distribution centers, for timely distribution of vital relief to the damaged areas, vehicles routing and emergency roadway repair operations. It minimizes the travel time and total cost and increases reliability of the routes. To solve the designed problem, two meta-heuristic algorithms, namely non-dominated sorting genetic algorithm-II (NSGAII) and multi-objective particle swarm optimization (MOPSO), are offered. Then, the accuracy of mathematical models and efficiency of algorithms are assessed through numerical examples in detail.

     

A Fuzzy Congestion Control Protocol Based on Active Queue Management in Wireless Sensor Networks with Medical Applications

Wireless Personal Communications - Wireless Sensor Network has been widely used in a variety of applications such as; medical, agriculture, military, monitoring environment and so on. In healthcare...     

Slip velocity and slip layer thickness in flow of concentrated suspensions

The rheological characterization of highly filled suspensions consisting of a Newtonian matrix (hydroxyl-terminated polybutadiene), mixed with two different sizes of aluminum powder (30% and above by volume) and two different sizes of glass beads (50% and above by volume), was performed using a parallel disk rheometer with emphasis on the wall slip phenomenon. The effects of the solid content, particle size, type of solid particle material, and temperature on slip velocity and slip layer thickness were investigated. Suspensions of small particles of aluminum (mean diameter of 5.03 μm) did not show slip at any concentration up to the maximum packing fraction. However, suspensions of the other particles exhibited slip at the wall, at concentrations close to their maximum packing fraction. In these suspensions, the slip velocity increased linearly with the shear stress, and at constant shear stress, the slip velocity increased with increasing temperature. The slip layer thickness increased proportionally with increasing size of the particles for the glass beads. Up to a certain value of (filler content/maximum packing fraction), ϕ/ϕ_m, the slip layer thickness divided by the particle diameter, δ/D_P, was 0, but it suddenly increased and reached a value that was independent of ϕ/ϕ_m and the temperature. On average, the ratio of δ/D_P was 0.071 for aluminum and 0.037 for glass beads. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 515–522, 1998     

Characterization and physical properties investigation of conducting polypyrrole/TiO2 nanocomposites prepared through a one‐step “in situ” polymerization method

Nowadays, nanocomposites are a special class of materials having unique physical properties and wide application potential in diverse areas. The present research work describes an efficient method for synthesis of a series of polypyrrole/titanium dioxide (PPy/TiO₂) nanocomposites with different TiO₂ ratios. These nanocomposites were prepared by one‐step in situ deposition oxidative polymerization of pyrrole hydrochloride using ferric chloride (FeCl₃) as an oxidant in the presence of ultra fine grade powder of anatase TiO₂ nanoparticles cooled in an ice bath. The obtained nanocomposites were characterized by Fourier‐transform infrared (FTIR), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and scanning electron microscope (SEM) techniques. The obtained results showed that TiO₂ nanoparticles have been encapsulated by PPy with a strong effect on the morphology of PPy/TiO₂ nanocomposites. Also, the synthesized PPy/TiO₂ nanocomposites had higher thermal stability than that of pure PPy. The investigation of electrical conductivity of nanocomposites by four‐point probe instrument showed that the conductivity of nanocomposite at low TiO₂ content is much higher than of neat PPy, while with the increasing contents of TiO₂, the conductivity decreases. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Cement-based sensors with carbon fibers and carbon nanotubes for piezoresistive sensing

Electrically conductive cementitious composites carrying carbon fibers and carbon nanotubes were developed and their ability to sense an applied compressive load through a measureable change in resistivity was investigated. Two types of cement-based sensors, one with carbon fibers alone and the other carrying a hybrid of both fibers and nanotubes, were considered. Direct comparisons were also made with traditional strain gauges mounted on the sensor specimens.Sensing experiments indicate that under cyclic loading, the changes in resistivity mimic both the changes in the applied load and the measured material strain with high fidelity for both sensor types. The response, however, is nonlinear and rate dependent. At an arbitrary loading rate, the hybrid sensor, containing a combination carbon fibers and nanotubes, produced the best results with better repeatability.     

Physiological Parameters of Silicon-Treated Maize Under Salt Stress Conditions

Silicon - The effects of silicon (Si) on Zea mays under salt stress conditions were investigated and the data was analyzed by cluster heat maps. The results indicated that the application of Si in...     

Application of Response Surface Methodology for Optimization of Water Treatment by Fe3O4/SiO2/TiO2 Core-Shell Nano-Photocatalyst

In the present work, Fe₃O₄/SiO₂/TiO₂ nano-photocatalyst with a core-shell structure was successfully used for the removal of Methylene Blue (MB) as a model organic pollutant from water. The resultant nanoparticles were characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, Brunauer–Emmett–Teller method, and Barrett–Joyner–Halenda method. Response surface methodology (Box–Behnken approach) was applied to optimize the removal of MB from water. This optimization was used to evaluate the effect of experimental variables and their interaction in achieving the optimum conditions in removal of MB from water which was measured via UV-visible spectroscopy. The optimum conditions were found to be at Si/Fe₃O₄ wt% = 17.35%, Ti/Fe₃O₄ wt% = 50.17%, and calcination temperature = 392°C with a 91.1% removal efficiency. Finally, a model was established and the predicted results from the model fitted well with the experimental values indicating that the optimization was successful.     

A new PI optimal linear quadratic state-estimate tracker for continuous-time non-square non-minimum phase systems

Based on the proportional-integral-derivative (PID) filter-shaping approach, this paper presents a new proportional-plus-integral (PI) optimal linear quadratic state estimator (LQSE) for the continuous-time non-square and non-minimum phase (NMP) multivariable systems. Together with the recently developed optimal linear quadratic tracker (LQT), the proposed LQSE-based tracker is able to optimally achieve good minimum phase-like tracking performances for a non-square NMP multivariable system with unmeasurable states and arbitrary command inputs.     

Oxidative Coupling of Methane in a Negative DC Corona Reactor at Low Temperature

Oxidative coupling of methane (OCM) in the presence of DC corona is reported in a narrow glass tube reactor at atmospheric pressure and at temperatures below 200°C. The corona is created by applying 2200V between a tip and a plate electrode 1.5 mm apart. The C₂ selectivity as well as the methane conversion are functions of methane‐to‐oxygen ratio, gas residence time, and electric current. At CH₄/O₂ ratio of 5 and the residence time of about 30 ms, a C₂ yield of 23.1% has been achieved. The main products of this process are ethane, ethylene, acetylene as well as CO and CO₂ with CO/CO₂ ratios as high as 25. It is proposed that methane is activated by electrophilic oxygen species to form methyl radicals and C₂ products are produced by a consecutive mechanism, whereas CO_x is formed during parallel reactions.