Solid Location Research Articles

A HYBRID ALGORITHM TO SOLVE THE FIXED CHARGE SOLID LOCATION AND TRANSPORTATION PROBLEM

In this paper, we propose a Hybrid Algorithm (HA) to solve the Fixed Charge Solid Location and Transportation problem (FCSLTP). The FCSLTP considers the cost of facility location and route fixed costs during transportation planning or load consolidation. The HA integrates two heuristics into the Genetic Algorithm framework to solve the FCSLTP. Genetic operations are used to select the best combination of facility locations while a greedy heuristic which uses some cost relaxations are used for the initial load allocation. An improvement heuristic, a modified stepping stone method, is then used to consolidate load allocations to realize further possible cost savings. Parameters used for the genetic operations were decided through preliminary studies. Computational studies using randomly generated data were performed to compare the HA solutions with the solutions obtained using CPLEX, a commercial solver. Performance comparison was done based on the quality of solution and computing time. The results suggest the solution approach is competitive.

Mixed convection of Al2O3-water nanofluid in a double lid-driven square cavity with a solid inner insert using Buongiorno’s two-phase model

The present paper investigates steady conjugate mixed convection in a double lid-driven square cavity including a solid inner body. The annulus is filled with water-Al2O3 nanofluid based on Buongiorno’s two-phase model. The top horizontal wall is maintained at a constant low temperature and moves to the right while the bottom horizontal wall is maintained at a constant high temperature and moves to the left. The governing equations are solved numerically using the finite element method. The governing parameters are the inner solid location (case 1-case 4), the nanoparticles volume fraction (0⩽ϕ⩽0.04), Reynolds number (1⩽Re⩽500), Richardson number (0.01⩽Ri⩽100), the size of the inner solid (0.1⩽D⩽0.7) and thermal conductivity of the inner solid (kw=0.01, 0.045, 0.1, 0.76 and 1.95 W/m °C). The other parameters; Prandtl number, Lewis number, Schmidt number, ratio of Brownian to thermophoretic diffusivity and the normalized temperature parameter are fixed at Pr=4.623,Le=3.5×105,Sc=3.55×104,NBT=1.1 and δ=155, respectively. The results show that the nanofluid strategy in such a cavity has a noticeable augmentation of heat transfer. However, at low Reynolds number, the addition of nanoparticles has an adverse effect on the Nusselt number when the Richardson number is very high. It is also found that a big size solid body can augment heat transfer in the case of high values of both the Reynolds and the Richardson numbers.

Positron Lifetime in Deformed AlSi10.9Mg0.17Sr0.06 Alloys

Positron annihilation lifetime spectroscopy (PALS) is one of the nuclear techniques used in material science. (PALT) measurements are used to study the behaviour of the defect concentration in a set of AlSi10.9Mg0.17Sr0.06 alloys. It has been shown that positrons can become trapped at imperfect locations in solids, and that their mean lifetime can be influenced by changes in the concentration of such defects. No changes have been observed in the mean lifetime values following saturation of the defect concentration. The mean lifetime and trapping rates were studied for samples deformed up to 34.9 %. The concentrations of defects range vary from 5.194x1015 to 1.934x1018 cm-3 for thickness reductions of 2.2 to 34.9 %. The range of the dislocation density varies from 1.465x 108 to 5.454x1010 cm/cm3 over the same range of deformations.

Defect Densities Using the Positron Annihilation Doppler Broadening Technique in Wrought Alloys 3003 and 3005

Positron Annihilation Doppler Broadening Spectroscopy (PADPS) is one of the nuclear techniques used in material science. PADPS measurements are used to study the behavior of defect concentration and dislocation density in a set of 3003 and 3005 wrought aluminum alloy. It has been shown that positrons can become trapped at imperfect locations in solids. The S-parameter can be influenced by changes in the concentration of such defects. There is no observed change in the Sparameter values after the saturation of defect concentration. The S-parameter and trapping rates for the samples deformed up to 10 percent were studied. The concentration of defect range varies from 1017 to 1018 cm-3 and from 1016 to 1017 cm-3 for 3003 and 3005 wrought Al alloy respectively. While trapping rate range varies from 1 x1010 to 1.2x1011 s-1 for 3003 and from 1 x109 to 1.2x1010 s-1 for 3005 wrought Al alloy.

DETECTING DEFECTS IN AIRCRAFT MATERIALS BY NUCLEAR TECHNIQUE (PAS)

Positron annihilation spectroscopy (PAS) is one of the nuclear techniques used in material science. The present measurements are used to study the behavior of defect concentration in one of the most important materials — aluminum alloy — which is a 7075 alloy. It has been shown that positrons can become trapped in imperfect locations in solids and their mean lifetime can be influenced by changes in the concentration of such defects. No changes have been observed in the mean lifetime values after the saturation of defect concentration. The mean lifetime and trapping rates were studied for samples deformed up to 58.3%. The concentration of defect range varies (from 1015 to 1018 cm-3) at the thickness reduction, (from 2.3 to 58.3%). The range of the dislocation density varies (from 108 to 1011 cm/cm3).

DISLOCATION AND DEFECT DENSITIES BY PAT IN 2024 AIRCRAFT MATERIAL USING TWO DIFFERENT ACTIVITY SOURCES

Positron annihilation lifetime spectroscopy (PALS) is a nuclear technique used in material science. Positron annihilation lifetime technique (PALT) measurements are used to study the behavior of defect concentration and dislocation density in a set of 2024 aluminum alloy. It has been shown that positrons can become trapped at imperfect locations in solids and their mean lifetime can be influenced by changes in the concentrations of such defects. No changes were observed in the mean lifetime after defect concentration became saturated. The mean lifetime and trapping rates for the samples deformed up to 36.4 percent. The concentration of defects range from 1.133 × 1016 to 2.061 × 1018 cm-3 at strains from 1.7 to 22.7%.

DETECTING DEFECTS IN AIRCRAFT MATERIALS BY NUCLEAR TECHNIQUE (PAS)

Positron annihilation spectroscopy (PAS) is one of the nuclear techniques used in material science. The present measurements are used to study the behavior of defect concentration in one of the most important materials aluminum alloys which is the 7075 alloy. It has been shown that positrons can become trapped at imperfect locations in solids and their mean lifetime can be influenced by changes in the concentration of such defects. No changes have been observed in the mean lifetime values after the saturation of defect concentration. The mean lifetime and trapping rates are studied for samples deformed up to 58.3%. The concentration of defect range vary from 1015 to 1018 cm -3 at the thickness reduction from 2.3 to 58.3%. The dislocation density varies from 108 to 1011 cm/cm 3.

STUDY OF TRAPPING RATE AND DEFECT DENSITY IN AlSi11.35Mg0.23 BY POSITRON ANNIHILATION TECHNIQUE

The measurements of Positron Annihilation Lifetime Technique (PALT) have been performed on AlSi 11.35 Mg 0.23 Alloys. It has been shown that positrons can become trapped at imperfect locations in solids and their mean lifetime can be influenced by changes in the concentration of such defects. No change has been observed in the mean lifetime values at the saturation of defect concentration. The trapping rates of positrons can be determined for thickness reduction up to 11% for dislocation. The concentration of defect (ρ') range varies from 8.65×1015 to 2.35×1018 cm -3 up to the maximum value of strain (ε) 0.23.