Curved beam element stiffness matrix formulation

Stiffness matrix of order 12 × 12, for a curved beam element has been formulated involving all the forces together, using Castigliano's theorem. Effects of transverse shear forces and tangential thrust are also taken into account. In earlier works, stiffness submatrices for the two uncoupled systems of forces are formulated independently and then they are combined to give the overall 12 × 12 matrix. A program subroutine, NEWCBM for the stiffness matrix formulation of curved beams has been written in FORTRAN which can be added to the element library of general purpose computer programs like SAP-IV and its improved versions. Example problems have been worked to check the accuracy of this formulation.     

Prediction of packed-bed catalytic reactor performance for a complex reaction (oxidation of o-xylene to phthalic anhydride)

Statistical best-fit kinetic and transport parameters are derived from temperature and yield profiles observed in a pilot-plant catalytic reactor in which o-xylene is oxidised with air to phthalic anhydride and its precursors. Published data are used to begin the search routine and the tuned parameters are seen to be plaubible. The overall model has good extrapolative power to the point where catalyst deactivation becomes apparent.     

Rationing mechanisms and inventory control-policy parameters for a divergent supply chain operating with lost sales and costs of review

We consider a static divergent two-stage supply chain with one distributor and many retailers. The unsatisfied demands at the retailers’ end are treated as lost sales, whereas the unsatisfied demand is assumed to be backlogged at the distributor. The distributor uses an inventory rationing mechanism to distribute the available on-hand inventory among the retailers, when the sum of demands from the retailers is greater than the on-hand inventory at the distributor. The present study aims at determining the best installation inventory control-policy or order-policy parameters such as the base-stock levels and review periods, and inventory rationing quantities, with the objective of minimizing the total supply chain costs (TSCC) consisting of holding costs, shortage costs and review costs in the supply chain over a finite planning horizon. An exact solution procedure involving a mathematical programming model is developed to determine the optimum TSCC, base-stock levels, review periods and inventory rationing quantities (in the class of periodic review, order-up-to S policy) for the supply chain model under study. On account of the computational complexity involved in optimally solving problems over a large finite time horizon, a genetic algorithm (GA) based heuristic methodology is presented.     

Unsteady flow between rectangular plates and between circular plates

An analysis is presented of the unsteady flow of a viscous incompressible fluid between two parallel infinitely long rectangular plates and between two parallel circular plates. The lower plate is fixed and the upper plate moves towards the lower plate. Full Navier-Stokes equations are used to obtain the pressure distribution as a function of the film thickness h(t) and the velocity $\text{h}\text{?}\text{(t)}$ of the upper plate. The inertia is taken into account and, for a given load on the upper plate, the sinkage relation between h and t is determined for various values of the Reynolds number. The departure from the classical inertialess solution is exhibited for various values of the two dimensionless parameters involved, one characterizing the load and the other gravity.     

An ant colony algorithm for scheduling in flowshops with sequence-dependent setup times of jobs

The problem of scheduling in flowshops with sequence-dependent setup times of jobs is considered and solved by making use of ant colony optimization (ACO) algorithms. ACO is an algorithmic approach, inspired by the foraging behavior of real ants, that can be applied to the solution of combinatorial optimization problems. A new ant colony algorithm has been developed in this paper to solve the flowshop scheduling problem with the consideration of sequence-dependent setup times of jobs. The objective is to minimize the makespan. Artificial ants are used to construct solutions for flowshop scheduling problems, and the solutions are subsequently improved by a local search procedure. An existing ant colony algorithm and the proposed ant colony algorithm were compared with two existing heuristics. It was found after extensive computational investigation that the proposed ant colony algorithm gives promising and better results, as compared to those solutions given by the existing ant colony algorithm and the existing heuristics, for the flowshop scheduling problem under study.     

χ measurements and optical limiting studies of 2-chloro-5-nitro-N′-[(1E)-phenylmethylidene] benzohydrazide with substituents

The nonlinear optical properties of hydrazones substituted with different donor groups were studied using single beam Z-scan technique with nanosecond laser pulses at 532 nm. The nonlinear response in these molecules was found to increase with increase in the donor strength of the substituted group. The χ⁽³⁾ value of these molecules is found to be of the order of 10⁻¹³ esu. The nonlinear refractive index (n₂) of the samples is found to be negative and the largest value of n₂ obtained for the strong donor-substituted molecule is −8.83 × 10⁻¹¹ esu. All samples show good optical limiting behavior at 532 nm. The best optical limiting behavior was observed with the molecule substituted by a strong electron donor.     

Liposome nano‐formulation with cationic polar lipid DOTAP and cholesterol as a suitable pH‐responsive carrier for molecular therapeutic drug (all‐trans retinoic acid) delivery to lung cancer cells

The molecular targeted drug ATRA demands a suitable carrier that delivers to the cancer site due to its poor bioavailability and drug resistance. ATRA, being a lipid with carboxylic acid, has been nano‐formulated as a cationic lipo‐ATRA with DOTAP:cholesterol:ATRA (5:4:1) and its pH‐responsive release, intracellular drug accumulation, and anticancer effect on human lung cancer (A549) cell line analysed. The analysis of the physicochemical characteristics of the developed lipo‐ATRA (0.8 µmol) revealed that the size of 231 ± 2.35 d.nm had a zeta potential of 6.4 ± 1.19 and an encapsulation efficiency of 93.7 ± 3.6%. The ATRA release from lipo‐ATRA in vitro was significantly (p ≤ 0.05) higher at acidic pH 6 compared to pH 7.5. The intracellular uptake of ATRA into lipo‐ATRA‐treated A549 cells was seven‐fold higher (0.007 ± 0.001 mg/ml) while only three‐fold uptake was observed in free ATRA treatment (0.003 ± 0.002 mg/ml). The lipo‐ATRA treatment caused a highly significant (p ≤ 0.001) decrease in percent cell viability at 48 h when compared with the free ATRA treatment. Overall, the results proved that the developed lipo‐ATRA has suitable physicochemical properties with enhanced ATRA release at acidic pH, while maintaining stability at physiologic pH and temperature. This resulted in an increased ATRA uptake by lung cancer cells with enhanced treatment efficiency. Hence, it is concluded that DOTAP lipo‐ATRA is a suitable carrier for ATRA delivery to solid cancer cells.     

A multi-objective genetic algorithm for scheduling in flow shops to minimize the makespan and total flow time of jobs

In this paper the problem of permutation flow shop scheduling with the objectives of minimizing the makespan and total flow time of jobs is considered. A Pareto-ranking based multi-objective genetic algorithm, called a Pareto genetic algorithm (GA) with an archive of non-dominated solutions subjected to a local search (PGA-ALS) is proposed. The proposed algorithm makes use of the principle of non-dominated sorting, coupled with the use of a metric for crowding distance being used as a secondary criterion. This approach is intended to alleviate the problem of genetic drift in GA methodology. In addition, the proposed genetic algorithm maintains an archive of non-dominated solutions that are being updated and improved through the implementation of local search techniques at the end of every generation. A relative evaluation of the proposed genetic algorithm and the existing best multi-objective algorithms for flow shop scheduling is carried by considering the benchmark flow shop scheduling problems. The non-dominated sets obtained from each of the existing algorithms and the proposed PGA-ALS algorithm are compared, and subsequently combined to obtain a net non-dominated front. It is found that most of the solutions in the net non-dominated front are yielded by the proposed PGA-ALS.