An AHP based heuristic DPSO algorithm for generating multi criteria production–distribution plan

Multi-criteria integrated production–distribution problems were solved by many researchers using different optimization techniques. A novel analytic hierarchy process (AHP) based heuristic discrete particle swarm optimization (DPSO) algorithm is proposed in this research for solving difficult production–distribution problems. A bearing manufacturing industry's case is considered in this paper and the mathematical model is formulated as mixed integer linear programming (MILP) problem considering multi-period, multi-product and multi-plant scenarios. The three major objectives considered are total cost reduction, minimization of change in labor levels and percentage under-utilization. The results of the AHP based heuristic DPSO algorithm are compared with the branch and bound algorithm results generated using LINGO software. The approach gives good near optimal solutions. In addition to the bearing manufacturing industry dataset, two other test datasets are also solved.     

Prediction and optimization of depth of penetration for stainless steel gas tungsten arc welded plates using artificial neural networks and simulated annealing algorithm

The quality of a weld joint is highly influenced by depth of penetration. Hence, accurate prediction and maximization of depth of penetration is highly essential to ensure a good-quality joint. This paper highlights the development of neural network model for predicting depth of penetration and optimizing the process parameters for maximizing depth of penetration using simulated annealing algorithm. The process parameters chosen for the study are welding current, welding speed, gas flow rate and welding gun angle. The chosen output parameter was depth of penetration. The experiments were conducted based on design of experiments using fractional factorial with 125 runs. Using the experimental data, feed-forward backpropagation neural network model was developed and trained using Levenberg–Marquardt algorithm. It was found that ANN model based on network 4-15-1 predicted depth of penetration more accurately. A mathematical model was also developed correlating the process parameters with depth of penetration for doing optimization. A source code was developed in MATLAB to do the optimization. The optimized process parameters gave a value of 3.778 mm for depth of penetration.     

Efficient out-of-core sorting algorithms for the Parallel Disks Model

In this paper,¹ we present efficient algorithms for sorting on the Parallel Disks Model (PDM). Numerous asymptotically optimal algorithms have been proposed in the literature. However, many of these merge based algorithms have large underlying constants in the time bounds, because they suffer from the lack of read parallelism on the PDM. The irregular consumption of the runs during the merge affects the read parallelism and contributes to the increased sorting time. In this paper, we first introduce a novel idea called the dirty sequence accumulation that improves the read parallelism. Next, we show analytically that this idea can reduce the number of parallel I/O’s required to sort the input close to the lower bound of . We verify experimentally our dirty sequence idea with the standard R-Way merge and show that our idea can reduce the number of parallel I/Os to sort on the PDM significantly.     

Structure and lithium ion conductivity of garnet-like Li5La3Sb2O12 and Li6SrLa2Sb2O12

Oxides with the nominal chemical compositions Li₅La₃Sb₂O₁₂ and Li₆SrLa₂Sb₂O₁₂ were prepared by solid-state reaction. The structures were refined by the Rietveld method using powder X-ray diffraction data. The synthesis of Li₅La₃Sb₂O₁₂ resulted in the well known garnet-related structure plus 5 wt.% of La₂LiSbO₆ in the bulk. In contrast to that, Li₆SrLa₂Sb₂O₁₂ could be synthesised in single garnet-related type phase. Lithium ion conductivities of Li₅La₃Sb₂O₁₂ and Li₆SrLa₂Sb₂O₁₂ were studied by the ac impedance method. The grain-boundary contribution to the total (bulk + grain-boundary) resistance is very small and about 5 and 3% for Li₅La₃Sb₂O₁₂ and Li₆SrLa₂Sb₂O₁₂, respectively, at 24 °C and decreases further with increase in temperature. Among the investigated compounds, Li₅La₃Sb₂O₁₂ exhibits the highest total (bulk + grain-boundary) and bulk ionic conductivity of 7.8 × 10⁻⁶ and 8.2 × 10⁻⁶ S cm⁻¹, respectively, at 24 °C. The structural data indicate that the coupled substitution Li + Sr ⇒ La leads to a closure of the bottle neck like O-O distances of the shared edges of neighbouring Li octahedra and therefore reduces the mobility of Li ions in Li₆SrLa₂Sb₂O₁₂. Scanning electron microscope (SEM) images of the Li₆SrLa₂Sb₂O₁₂ compound revealed well crystallised large homogeneous grains (∼4.8 μm) and the grains were in good contact with the neighbouring grain, which leads to a smaller grain-boundary contribution to the total resistance.     

DSP-based electric power assisted steering using BLDC motor

This paper introduces a design and implementation of electrically assisted power steering (EAS) using BLDC motor for a vehicle. The control architecture consists of two layers of control, namely the vehicle speed associated control and the torque assist control. In the higher level of control architecture, the vehicle speed controller works as an assistance level controller for the steering effort. In the lower level, the torque controller gives the effort level control. This has been realized by torque sensor and vehicle sensor interfaced in the DSP. For implementing in the system, a DSP-based BLDC motor controller with three-phase inverter module is specially designed using Hall-effect sensor feedback and a single dc-link current sensor. This work is implemented in a Light Commercial Vehicle having a recirculating ball type gear. This is for the first time (EAS) being implemented for this type of vehicle any where in the world. Generally, EAS having clutch to disconnect the motor in high speed or abnormal conditions from the gear box. In this implementation the motor is directly coupled to gearbox without clutch and all abnormalities are handled by the processor. This is implemented without modifying the vehicle supply system like changing the existing alternator or rating of the battery and using the existing sensors. The design is such a way that the feel of the driver assistance can be varied easily at any time. The performance of the control system is experimentally verified and it is tested in one of the Light Commercial Vehicle (LCV).     

Pair-wise key agreement and hop-by-hop authentication protocol for MANET

In MANET, the most important issues are authentication of data packet in the network. Due to the hostile environment, security is major concern while data transmission. In order to overcome this issue, in this paper, we propose hop by hop group key agreement protocol where each node generates pairwise key for encryption of data. The session key is generated only between the nodes which is carrying the data packet for transmission. The key exchange can be performed between two nodes before data transmission. Ni constructs Lagrange interpolating polynomial with degree n ? 1. Each Ni broadcasts the generated polynomial. After that, group key agreement protocol is used to provide complete authentication for those nodes. Simulation result show that the proposed algorithm is efficient as it minimizes bandwidth usage, delay, packet drop, and overhead, as well as fulfills all primary security concern, with improved delivery ratio and throughput.     

Effects of chicken eggshell filler size on the processing,mechanical and thermal properties of PVC matrix composite

The effects of filler particle size of poly(vinyl chloride)/chicken eggshell powder (PVC/ESP) composites on the processing, tensile properties, morphology and thermal degradation were investigated. The mixing of composites was done using Rheomix internal mixer. The processing torque of PVC/ESP composite at a particle of 0.2 μm exhibits lower processing torque compared to that at a particle size of 7 μm due to the dispersive resistance from larger ESP filler particles. Good interfacial adhesion exists between the filler and matrix in composites prepared via a filler particle size of 0.2 μm, which has improved the tensile strength and modulus of PVC/ESP composite compared to a filler particle size of 7 μm as justified from FESEM images on the tensile fracture surface of the composites. Thermogravimetric analysis results show that the filler particle size of 0.2 μm composite exhibits higher thermal stability compared to the filler particle size of 7 μm composite.     

Physical and optical properties of HfO2 NPs – Synthesis and characterization in finding its feasibility in opto-electronic devices

HfO₂ nanoparticles (HfO₂ NPs) with different precursors (NaOH, H₂O, ethanol) were synthesized by a simple co-precipitation method. FTIR and EDX spectroscopy analysis shows the Stoichiometries composition of HfO₂ NPs. X-ray diffraction pattern analysis revealed that the as prepared and calcined HfO₂ NPs are respectively amorphous and polycrystalline nature. TEM analysis confirms that the morphology of the calcined HfO₂ NPs is spherical in shape with less agglomeration. The crystallite size was evaluated to be 51 nm, 37 nm and 30 nm respectively, for the precursors NaOH, H₂O and ethanol used for HfO₂ NPs. SEM analysis shows spherical, rock and sponge like surface morphology respectively, for the precursors NaOH, H₂O and ethanol used for HfO₂ NPs. UV–visible spectroscopy analysis revealed that the optical band gap energy of NaOH, H₂O and ethanol precursors used HfO₂ NPs were respectively 5.50 eV, 5.52 eV and 5.50 eV. The observed optical properties indicated the feasibility of utilizing these NPs as anti reflection layers in solar cells and for the construction of poultry farms to save energy. The estimated dielectric constant value indicated that these NPs could be used to prepare dielectric layers in thin film transistor.     

Mixed Mode Stress Intensity Factor Determination of Multiple Cracks in Hollow Circular Pipe

Failure of pressure vessels and piping due to high temperature applications occurs due to the formation of fatigue cracks caused by cyclic load. It is well known that, the consequences of collapses of pipes causing enormous disruption of daily life. Thus there is a need to design and manufacture the pipes with precision and care. The major cause of crack nucleation in pipes is due to corrosion and internal fluid pressure. The crack-tip stresses are determined using stress intensity factor (SIF). In the present work an attempt has been made to determine the SIF for multiple cracks in a circular pipe subjected to internal fluid pressure. Two surface cracks of same size were introduced at the inner wall of the tube. The crack depth ratio (a/t) ranging between 0.1 and 0.5 and crack aspect ratio (a/c) of 0.6 and 1.0 was considered. Internal fluid pressure of 100 MPa was applied at the inner surface of the pipe and the corresponding SIF was measured. SIF values were calculated with consideration of mode-II and mode-III fracture in order to predict the exact SIF. As available SIF solutions of cracked pipes are limited to mode-I fracture, present work presents the influence of additional influence of mode-II and mode-III fracture. It is observed that, as crack depth ratio increases, SIF also increases considerably for semi-circular cracks. Higher SIF values were observed at the crack surface region [S/S ₀ = ±1] compared to crack middle [S/S ₀ = 0] region. A crossover in SIF was noted at a crack depth ratio of 0.3. At higher crack depths, SIF values decrease at the crack surface region due to additional influence of mode-II and mode-III fracture. In contrast to semi-circular cracks, SIF values are higher at the crack surface region for semi-elliptic cracks irrespective of the crack depths.     

Investigation of the mechanical behavior and vibration characteristics of thin walled glass/carbon hybrid composite beams under a fixed-free boundary condition

In the present work, woven fabric glass laminate is modified by interplying high modulus carbon fabric layers for improving the stiffness to weight ratio to enable good performance in dynamic conditions. The glass, carbon, and hybrid of glass/carbon laminates were fabricated with two different stacking sequences by hand layup method and tested for evaluating the mechanical properties with considerable trials. The vibration characteristics of composite beams were experimentally studied by impulse excitation techniques under fixed-free boundary conditions. The stacking sequence of beams influences the mechanical properties and vibration characteristics. The modal response of tested samples are compared and discussed.