Heuristic algorithms for the Capacitated Location-Routing Problem and the Multi-Depot Vehicle Routing Problem

The Capacitated Location-Routing Problem (CLRP) is a NP-hard problem since it generalizes two well known NP-hard problems: the Capacitated Facility Location Problem (CFLP) and the Capacitated Vehicle Routing Problem (CVRP). The Multi-Depot Vehicle Routing Problem (MDVRP) is known to be a NP-hard since it is a generalization of the well known Vehicle Routing Problem (VRP), arising with one depot. This thesis addresses heuristics algorithms based on the well-know granular search idea introduced by Toth and Vigo (2003) to solve the CLRP and the MDVRP. Extensive computational experiments on benchmark instances for both problems have been performed to determine the effectiveness of the proposed algorithms. This work is organized as follows: Chapter 1 describes a detailed overview and a methodological review of the literature for the the Capacitated Location-Routing Problem (CLRP) and the Multi-Depot Vehicle Routing Problem (MDVRP). Chapter 2 describes a two-phase hybrid heuristic algorithm to solve the CLRP. Chapter 3 shows a computational comparison of heuristic algorithms for the CLRP. Chapter 4 presents a hybrid granular tabu search approach for solving the MDVRP.

Heuristic algorithms for the travelling deliveryman problem

Algoritmi euristici per la risoluzione del Travelling DEliveryman Problem

Ideal site for ventricular anchoring of artificial chordae in mitral regurgitation

Surgical treatment of mitral leaflet prolapse using artificial neochordae shows excellent outcomes. Upcoming devices attempt the same treatment in a minimally invasive way but target the left ventricular apex as an anchoring point, rather than the tip of the corresponding papillary muscle. In this study, cine cardiac magnetic resonance imaging was used to compare these 2 different anchoring positions and their dynamic relationship with the mitral leaflets.

Single-Molecule Junctions Based on Nitrile-Terminated Biphenyls: A Promising New Anchoring Group

We present a combined experimental and theoretical study of the electronic transport through single-molecule junctions based on nitrile-terminated biphenyl derivatives. Using a scanning tunneling microscope-based break-junction technique, we show that the nitrile-terminated compounds give rise to well-defined peaks in the conductance histograms resulting from the high selectivity of the N-Au binding. Ab initio calculations have revealed that the transport takes place through the tail of the LUMO. Furthermore, we have found both theoretically and experimentally that the conductance of the molecular junctions is roughly proportional to the square of the cosine of the torsion angle between the two benzene rings of the biphenyl core, which demonstrates the robustness of this structure-conductance relationship.

THERMORESPONSIVE PROPERTIES OF GOLD HYBRID NANOPARTICLES OF POLY(DI(ETHYLENE GLYCOL) METHYL ETHER METHACRYLATE) (PDEGMA) AND ITS BLOCK COPOLYMERS WITH DIFFERENT ANCHORING REGIMES

Thermo-responsive materials have been of interest for many years, and have been studied mostly as thermally stimulated drug delivery vehicles. Recently acrylate and methacrylates with pendant ethylene glycol methyl ethers been studied as thermo responsive materials. This work explores thermo response properties of hybrid nanoparticles of one of these methacrylates (DEGMA) and a block copolymer with one of the acrylates (OEGA), with gold nanoparticle cores of different sizes. We were interested in the effects of gold core size, number and type of end groups that anchored the chains to the gold cores, and location of bonding sites on the thermo-response of the polymer. To control the number and location of anchoring groups we using a type of controlled radical polymerization called Reversible Addition Fragmentation Transfer (RAFT) Polymerization. Smaller gold cores did not show the thermo responsive behavior of the polymer but the gold cores did seem to self-assemble. Polymer anchored to larger gold cores did show thermo responsivity. The anchoring end group did not alter the thermoresponsivity but thiol-modified polymers stabilized gold cores less well than chains anchored by dithioester groups, allowing gold cores to grow larger. Use of multiple bonding groups stabilized the gold core. Using block copolymers we tested the effects of number of thiol groups and the distance between them. We observed that the use of multiple anchoring groups on the block copolymer with a sufficiently large gold core did not prevent thermo responsive behavior of the polymer to be detected which allows a new type of thermo-responsive hybrid nanoparticle to be used and studied for new applications.

Technical communication in the global context : a heuristic approach to disciplinary identity and pedagogical practices

There is nothing new or original in stating that the global economy directly impacts the profession of technical communicators. The globalization of the workplace requires that technical communicators be prepared to work in increasingly linguistically and culturally diverse contexts. These new exigencies have natural repercussions on the research and educational practices of the field In this work, I draw on rhetoric, linguistics, and literacy theory to explore the definition, role and meaning of the global context for the disciplinary construction of professional and technical communication. By adopting an interdisciplinary and diachronic perspective, I assert that the global context is a heuristic means for sophisticating the disciplinary identity of the field and for reinforcing its place within the humanities. Consequently, I contend that the globalization of the workplace is a kairotic moment for underscoring the rhetorical dimension of professional and technical communication.

A COMPARATIVE STUDY OF HEURISTIC OPTIMIZATION ALGORITHMS

Heuristic optimization algorithms are of great importance for reaching solutions to various real world problems. These algorithms have a wide range of applications such as cost reduction, artificial intelligence, and medicine. By the term cost, one could imply that that cost is associated with, for instance, the value of a function of several independent variables. Often, when dealing with engineering problems, we want to minimize the value of a function in order to achieve an optimum, or to maximize another parameter which increases with a decrease in the cost (the value of this function). The heuristic cost reduction algorithms work by finding the optimum values of the independent variables for which the value of the function (the “cost”) is the minimum. There is an abundance of heuristic cost reduction algorithms to choose from. We will start with a discussion of various optimization algorithms such as Memetic algorithms, force-directed placement, and evolution-based algorithms. Following this initial discussion, we will take up the working of three algorithms and implement the same in MATLAB. The focus of this report is to provide detailed information on the working of three different heuristic optimization algorithms, and conclude with a comparative study on the performance of these algorithms when implemented in MATLAB. In this report, the three algorithms we will take in to consideration will be the non-adaptive simulated annealing algorithm, the adaptive simulated annealing algorithm, and random restart hill climbing algorithm. The algorithms are heuristic in nature, that is, the solution these achieve may not be the best of all the solutions but provide a means to reach a quick solution that may be a reasonably good solution without taking an indefinite time to implement.