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This paper investigates an aircraft-target assignment problem in consideration of deconfliction. The aircraft-target assignment problem is the problem to assign available aircrafts and weapons to targets that should be attacked, where the objective function is to minimize the total expected damage of aircrafts. Deconfliction is the way of dividing airspaces for aircraft flight to ensure the safety while performing the mission. In this paper, mixed integer programming model is suggested, where it considers deconfliction between aircrafts. However, the suggested MIP model is non-linear and limited to get solution for large size problem. The 2-phase decomposition model is suggested for efficiency and computation, where in the first phase target area is divided into sectors for deconfliction and in the second phase aircrafts and weapons are assigned to given targets for minimizing expected damage of aircraft. The proposed decomposition model shows outperforms the model developed for comparison in the computational experiment.

Production planning and scheduling models for the semiconductor fabrication manufacturing are suggested in various types according to the objectives and factors taken into consideration. The lead time is one of the important factors in production planning, but there does not exist a simple way to describe and include it in the model. In this paper, the clearing time method is suggested to model the lead time in the fabrication process of the semiconductor manufacturing, so that the dynamically changing environment on the lead time and work in process (WIP) status are considered. It is shown through the experimental computation that the suggested model yields the accurate description on the lead time on the planning model, and the appropriate planning model with good results for the important performance measures in the semiconductor manufacturing.

Numerous studies have been studied to provide an efficient solution for the Nurse Rostering Problem (NRP), most of which have suffered from its complexity arising from incorporating nurse`s work shift and ability. The test-bed data for the NRP is released for the public Competition in 2010. This study suggests a new mixed integer programming for Nurse Rostering Problem and develops a hybrid approach, where a hierarchical decomposition and the corresponding optimization are combined. The computation experiment is performed to show that the suggested algorithms may give a better solution in various instances, compared to the one appeared in the literature.

Highly advanced technology products are manufactured on the series of equipment having various characteristics and requirements. The deposition process of organic light emitting diode, for example, is performed in chambers for a long manufacturing time, while various product devices belonging to the same family can be processed in sequence before the preventive maintenance schedule or the refill of chemical gas required. The deposition process plays as a bottleneck, and its productivity of the schedule is critical to the upstream low-temperature poly silicon process and the downstream encapsulation and module processes as well. The batch family scheduling problem is formulated using the mixed-integer programming (MIP) in consideration of the family setups, lot sizing, supplementary mask tools requirements, and material exhaustion requirements. It is shown that the planning and scheduling decisions can be made simultaneously in an integrated model, and that it can be implemented in the actual manufacturing line. Through the optimized model analysis, the capacity can be enhanced by 20∼30 % without losing the throughput and demand satisfaction as well.

This paper first formulates a binary integer programming (BIP) model that minimises C max for a multi-stage flexible job shop floor with machine compatibility. Due to a computational limitation, the exact optimal model is then relaxed as a linear programming model. The output from the relaxation model then turns into the objective of the BIP-based real-time scheduling (RTS) heuristic model. The RTS heuristic requires an iteration to calculate the final C max. At each iteration, the RTS heuristic assigns just one job to the earliest available machines. Since the set of jobs and machines included in the RTS model is relatively small, RTS can be solved in a very short computational time. We evaluate an overall effectiveness (in terms of solution quality and run time) of the RTS heuristic by way of computer experiments.

Publisher Summary This chapter presents the finite element linear buckling analysis of folded plate structures using adaptive h-refinement methods. The variable-node flat shell element used possesses a drilling D.O.F. that, in addition to improvement of the element behavior, permits an easy connection to other elements with six degrees of freedom per node. For the variable-node membrane elements with a drilling D.O.F., the Allman-type interpolations are used for the basic behavior of the element. The variable-node plate bending element is formulated based on Reissner–Mindlin plate theory to account for the shear deformation and has the substitute shear strain fields. The adaptive mesh refinement is normally performed after an initial solution has already been made available, and regions of the solution domain where the accuracy is not satisfactory have been identified according to a prescribed set of criteria. This process can be iterated using the last solution as the new initial solution. Two criteria are essential for adaptive mesh refinement—stopping criterion and refinement criterion. The stopping criterion is used to decide whether the obtained error is within the prescribed maximum error tolerance, and the refinement criterion is used to judge whether an element is to be refined at each iteration step.

Enhanced three-dimensional finite elements for geometrically nonlinear analysis of cable-supported structures are presented. The cable element, derived by using the concept of an equivalent modulus of elasticity and assuming the deflection curve of a cable as catenary function, is proposed to model the cables. The stability functions for a frame member are modified to obtain a numerically stable solution. Various numerical examples are solved to illustrate the versatility and efficiency of the proposed finite element model. It is shown that the finite elements proposed in this study can be very useful for geometrically nonlinear analysis as well as free vibration analysis of three-dimensional cable-supported structures.

A tendon model that can effectively be used in finite element analyses of prestressed concrete (PSC) structures with bonded tendons is proposed on the basis of the bond characteristics between a tendon and its surrounding concrete. Since tensile forces between adjacent cracks are transmitted from a tendon to concrete by bond forces, the constitutive law of a bonded tendon stiffened by grouting is different from that of a bare tendon. Accordingly, the apparent yield stress of an embedded tendon is determined from the bond-slip relationship. The definition of the multi-linear average stress-strain relationship is then obtained through a linear interpolation of the stress difference at the post-yielding stage. Unlike in the case of a bonded tendon, on the other hand, a stress increase beyond the effective prestress in an unbonded tendon is not section-dependent but member-dependent. The tendon stress unequivocally represents a uniform distribution along the length when the friction loss is excluded. Thus, using a strain reduction factor, the modified stress-strain curve of an unbonded tendon is derived by successive iterations. The validity of the proposed two tendon models is verified through correlation studies between analytical and experimental results for PSC beams and slabs.

In this study, a new smart beam finite element is proposed for the finite element modeling of beam-type smart structures that are equipped with bonded plate-type piezoelectric sensors and actuators. Constitutive equations for the direct piezoelectric effect and converse piezoelectric effect of piezoelectric materials are considered in the formulation. By using a variational principle, the equations of motion for the smart beam finite element are derived. The proposed 2-node beam finite element is an isoparametric element based on Timoshenko beam theory. The proposed smart beam finite element is applied to the free vibration control adopting a constant gain feedback scheme. The electrical force vector, which is obtained in deriving an equation of motion, is the control force equivalent to that in existing literature. Validity of the proposed element is shown through comparing the analytical results of the verification examples with those of other previous researchers. With the use of smart beam finite elements, simulation of free vibration control is demonstrated by sensing the voltage of the piezoelectric sensors and by applying the voltages to the piezoelectric actuators.

The finite element linear buckling analysis of folded plate structures using adaptive h-refinement methods is presented in this paper. The variable-node flat shell element used in this study (CLS, Choi and Lee, 1996) possesses the drilling D.O.F. which, in addition to improvement of the element behavior, permits an easy connection to other elements with six degrees of freedom per a node. Accordingly, the folded plate structures, for which it is hard to find the analytical solutions, can be analyzed using these developed flat shell elements. By introducing the variable-node elements, which have physical mid-side nodes, some difficulties associated with connecting the different layer patterns, which are common in the adaptive h-refinement on quadrilateral mesh, can be overcome. To obtain better stress field for the error estimation, the super-convergent patch recovery is used. The convergent buckling modes and the critical loads associated with these modes can be obtained. Analysis results of a few numerical examples are shown and compared with other researchers' results available.

The emergency vehicle location problem to determine the number of ambulance vehicles and their locations satisfying a required reliability level is investigated in this study. This is a complex nonlinear issue involving critical decision making that has inherent stochastic characteristics. This paper studies an iterative optimization algorithm with parameter estimation to solve the emergency vehicle location problem. In the suggested algorithm, a linear model determines the locations of ambulances, while a hypercube simulation is used to estimate and provide parameters regarding ambulance locations. First, we suggest an iterative hypercube optimization algorithm in which interaction parameters and rules for the hypercube and optimization are identified. The interaction rules employed in this study enable our algorithm to always find the locations of ambulances satisfying the reliability requirement. We also propose an iterative simulation optimization algorithm in which the hypercube method is replaced by a simulation, to achieve computational efficiency. The computational experiments show that the iterative simulation optimization algorithm performs equivalently to the iterative hypercube optimization. The suggested algorithms are found to outperform existing algorithms suggested in the literature.

Film-like morphology of retained austenite is observed at low isothermal temperatures, whereas blocky morphology of retained austenite appears at high temperatures in a bainitic Fe–3%Si–0.45%C–X steel. Amount of retained austenite increases with increasing temperature, exhibiting a peak at around 350 °C, above which it decreases with increasing temperature.

The general theoretical solution for the wavespeeds and damping derived in Part I of this work, are incorporated into the computer code. In this study the code is used in a parametric study of the influence of excitation frequency and variations in material properties on propagation velocity and damping. Compressional wave velocity for waves of the first kind is shown to vary as a function of the frequency–permeability product, with a zone where wavespeed transitions from a lower bound value to a higher bound value with increasing values of the product. Damping is seen to be a maximum where the rate of change in wavespeed is greatest. Waves of the second kind also show a transition in wavespeed from near zero at low values of the frequency–permeability product to an upper bound value at higher values of the product.

This work presents theoretical and numerical treatments of wave propagation and damping in saturated porous media. In Part I a closed-form solution for wave propagation velocity and damping in fully saturated porous media is derived for a fully coupled model with compressible solid grains and pore water. This solution demonstrates existence of two types of compression waves, termed waves of the first and second kinds. In Part II of this work the theoretical solution is incorporated into the numerical code and the code is used in a parametric study on wave propagation velocity and damping.

In this paper a three-dimensional dynamic analysis program for saturated porous rocks and soils is presented, The theoretical formulations incorporated in the proposed computer program are the extension of Biot's two-phase theory to non-linear region. Numerical study using the program is carried out to demonstrate the three-dimensional features of the program and to show the effects of pore water on the dynamic response of underground openings in saturated rock masses. It is shown that underground openings in saturated porous media could be significantly more vulnerable to the potential damages associated with high motions and shear failure that those in dry media.

A three‐dimensional dynamic analysis program for saturated porous‐rocks and soils (MPDAP‐3D) is developed in this study. The theoretical formulations incorporated in the proposed computer program are the extension of Biot’s two‐phase theory to non‐linear region. The generalized Hoek and Brown model is used to represent the skeleton constitutive relation. A three‐dimensional elasto‐plastic matrix for the generalized Hoek and Brown model is derived by extending two‐dimensional formulation. Numerical study for typical verification problems is carried out to show the validation of the computational algorithms of the computer program.

A state-of-the-art report on the new finite elements formulated by the addition of nonconforming displacement modes has been presented. The development of a series improved nonconforming finite elements for the analysis of plate and shell structures is described in the first part of this paper. These new plate and shell finite elements are established by the combined use of different improvement schemes such as; the addition of nonconforming modes, the reduced (or selective) integration, and the construction of the substitute shear strain fields. The improvement achieved may be attributable to the fact that the merits of these improvement techniques are merged into the formation of the new elements in a complementary manner. It is shown that the results obtained by the new elements give significantly improved solutions without any serious defects such as; the shear locking, spurious zero energy mode for the linear as well. as nonlinear benchmark problems. Recent developments in the transition elements that have a variable number of mid-side nodes and can be effectively used in the adaptive mesh refinement are presented in the second part. Finally, the nonconforming transition flat shell elements with drilling degrees of freedom are also presented.

A simulation model of patient throughput in the community healthcare center (CHC) is developed to appraise imperative variables of interest and to examine how each variable effect desired performance measures. To blend analytical methods’ mathematical supremacy with the modeling-ability of simulation, meta-modeling approach is applied to abridge simulations’ computational burden. A single meta-model represents a single performance measure. For any system, the solution found using a single metamodel representing a specific performance measure i.e. system throughput may be suboptimal having detrimental effect on other crucial performance measures i.e. resource utilization, work-inprocess, lead times etc. if not considered during analysis. Thus, it’s emphasized in this research to develop all possible met-models representing all the crucial performance measures individually for the purpose of overcoming aforesaid drawback i.e. chances of finding/implementing a sub-optimal solution. The eminent advantage: the final solution using abovementioned technique will qualify itself as a real optimal solution no short in terms of all crucial performance measures for the system. Obviously, this technique will be helpful for management to predict the impact of selected independent factors on daily service levels, will serve as suggestion models for day-to-day decisions assistance, resources pro-active management and utilization, extrapolation etc. to maintain desired service levels.

The present paper is concerned with the improvement of a finite element for the analysis of plate bending structures. The element formulation is based upon the Mindlin plate concept. The displacement field of this element is formed by adding non-conforming modes to two rotational displacement components of an 8-node plate element. The element has the requisite numbers of zero eigenvalues associated with rigid body modes to avoid the spurious zero energy mode. It is shown that the results obtained by the element converged to the exact solutions very rapidly as the mesh is refined and exhibited reliable solutions through numerical studies for standard benchmark problems. This element is shown to overcome the shear locking problem completely in a very thin plate situation, even for irregular meshes.

Two new plate elements (designated as NC8-A and NC8-B) that are established by the combined use of reduced integration and addition of nonconforming displacement modes are presented in this paper. The results obtained by both NC8-A and NC8-B elements converged to the exact solutions very rapidly as the mesh is refined. These elements are also shown to be applicable to the wide range of plate problems, giving a high accuracy for extremely thin plate in particular.

The paper presents the computation results for the Dubrovnik steel cable-stayed bridge with a total span of 474 m by using two different sources of wind action. The first set of data was obtained by direct measurements of the wind direction and velocity, second values, acting on the structure at the end of its construction and the second set of data was based on the simulated wind action in the tunnel carried out by prof. G. Sedlacek (Germany). The Bora wind in Croatia is known as a catabatic, very cold and locally changeable wind blowing from the direction of the towards the Adriatic coastline, with the maximum measured wind gusts over 70 m/s. This term, Bora, is used for other winds with similar characteristics in the whole world. The investigations of the turbulence characteristics of the Bora wind in the bottom layer considering the aspect of the dynamic action on the structures are currently performed and have not been completed yet. It is interesting to note that the most extensive investigations on the Bora wind action in Croatia have been carried out by Japanese in the period 1970/73 ; their objective was to study this natural phenomenom in the bottom layer in the order to reach conclusions about the action of a similar wind Oroshi in Japan. The recently completed measurements of the second values of wind gusts at three points at different elevations (10, 52 and 140 m) at the pile of the Dubrovnik bridge and the fourth measurement point at the order end of the bridge have made it possible to present the actual action of this highly catabatic wind. The results obtained by this computation were compared with the results obtained by computations based on the values of the simulated wind action in the tunnel whit the assumed wind direction and velocity. The paper proves that for the winds of the Bora type the tunnel simulations (the wind tunnel tests) are not suitable so that measurements at actual locations are required. The investigations were performed according to the EUROCODE recommendations and they represent the basis for the development of the Croatian codes in the field of the dynamic wind action upon the structure.