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The key to the understanding of the mechanical behavior of dual phase (DP) steels is to a large extent to be found in the microstructure. The microstructure is in its turn a result of the chemical composition and the process parameters during its production. In this thesis the connection between microstructure and mechanical properties is studied, with focus on the microstructure development during annealing in a continuous annealing line. In-line trials as well as the lab simulations have been carried out in order to investigate the impact of alloying elements and process parameters on the microstructure. Further, a dislocation model has been developed in order to analyze the work hardening behavior of DP steels during plastic deformation. From the in-line trials it was concluded that there is an inheritance from the hot rolling process both on the microstructure and properties of the cold rolled and annealed product. Despite large cold rolling reductions, recrystallization and phase transformations, the final dual phase steel is still effected by process parameters far back in the production chain, such as the coiling temperature following the hot rolling. Lab simulations showed that the microstructure and consequently the mechanical properties are impacted not only by the chemical composition of the steel but also by a large number of process parameters such as soaking temperature, cooling rate prior to quenching, quench and temper annealing temperature. / QC 20101004

The large magneto-crystalline anisotropy energy of the L10 phase has pushed the interest to the FePt nanoparticles to get smallest possible not superparamagnetic particles for magnetic data storage media. The DC magnetron sputtering process, in an inert gas atmosphere and subsequently ejection into high vacuum via differential pumping in addition with a newly constructed light furnace, allows us to have a predeposition annealing of FePt nanoparticles. The advantage compared to wet chemical process route is, that we can prevent the growing of particles on a substrate. In order to determine the experimentally hardly accessible temperature of the particles, the thermal history of the particles is rather calculated from the interaction with the light field along the flight path through the light furnace used for the in-flight annealing. The results obtained for the particle temperature are corroborated by experimental findings on the sintering of agglomerated particles and change in magnetic properties due to heating over the L10 stability temperature. The experiments reveal that the effect of the thermal treatment on both the structural and magnetic properties of the FePt nanoparticles strongly depends on the particles’ crystal structure. The magnetic behavior shows a size depending effective uniaxial magnetic anisotropy constant. This behavior is strongly correlated to the structure of the 5 nm to 8 nm L10 FePt particle.

Recently a periodic surface model was developed to assist geometric construction in computer-aided nano-design. This implicit surface model helps create super-porous nano structures parametrically and support crystal packing. In this thesis, a new approach for pathway search in phase transition simulation of crystal structures is proposed. The approach relies on the interpolation of periodic loci surface models. Respective periodic plane models are reconstructed from the positions of individual atoms at the initial and final states, and surface correspondence is found using a Simulated Annealing-like algorithm. With geometric constraints imposed based on physical and chemical properties of crystals, two surface interpolation methods are used to approximate the intermediate atom positions on the transition pathway in the full search of the minimum energy path. This hybrid approach integrates geometry information in configuration space and physics information to allow for efficient transition pathway search. The methods are demonstrated by examples of FeTi, VO2, and FePt. Additionally, two new particle swarm optimization (PSO) algorithms are developed and applied to crystal structure relaxation of the initial and final states. The PSO algorithms are integrated into the Quantum-Espresso open-source software package and tested against the default Broyden-Fletcher-Goldfarb-Shanno relaxation method.

The present work focuses on the exploration of the conformational space of biological active peptides in different conditions with the aim of characterizing their conformational profile. Different techniques have been used within the molecular mechanics framework. A first hurdle is encountered in the exploration as the exhaustiveness of the exploration and the definition of a criterion for stopping the procedure were not well defined at the beginning of the present work. A solution to this problem is presented in the second chapter for the iterative simulated annealing.Determining the bioactive conformation is a requirement for the design of peptidomimetics in computer-aided drug design. The bioactive conformation can be simplified by the moieties that are known to interact with the receptor and the relative distances between these moieties, and this schematic entity is termed pharmacophore. The pharmacophore can be used to screen three-dimensional databases of molecules for the search of peptidomimetics. The compounds obtained in the search can be subsequently tested for activity and a new group of lead compounds can be thus identified. In chapter 3 an example of this procedure is described with the aim of obtaining a new group of bradykinin antagonists.Peptides have been traditionally considered as flexible molecules especially in polar solvents like water. This flexibility is difficult to measure by experimental techniques and as a consequence peptides have been regarded as molecules lacking of structure under such conditions. On the other hand, biological active peptides are known to interact with their receptors in a preferred conformation, often termed as the bioactive conformation. The most accepted hypothesis for explaining the interaction of peptides and their receptors is the induced fit. Thus, the peptide will exhibit in solution conformational motives that are part of the conformation adopted in the receptor. Subsequent to the binding of the peptide to the receptor, the conformation in solution will be modified in order to optimize the interaction of the peptide to the receptor. Therefore, a contradiction appears to exist between the need for certain degree of structure in the peptide prior to the receptor binding and the inherent lack of structure of peptides in solution. It has been argued in some instances that the binding of the peptide to the biological membrane is a prerequisite for the adoption of the bioactive conformation and the subsequent binding to the receptor. In chapters 4 and 5 this hypothesis will be criticized and an alternative hypothesis will be presented.Recently, it has been reported several instances were the folding of peptides has been simulated by means of long molecular dynamics trajectories. A problem arises when the wealth of conformations obtained has to be classified in terms of their respective degree of folding. In chapter 4 a novel methodology is described for the classification and grouping of the peptide structures based on the presence of structural motifs and the similarities among them. This methodology can prove very useful as it almost automated and it does not present any limitation regarding the size of the peptide or protein of study.In order to follow what are the problems arising when the size and the flexibility of peptides are increased, the sequence of chapters of the present study is presented with increasing size. Thus, in chapter 2 the conformational profile of 4-residue long farnesyltransferase inhibitors is studied by means of the iterative simulated annealing procedure. The first part of chapter 3 deals with a bradykinin antagonist, Hoe 140. Although Hoe 140 with 10 residues is larger than the 4-residue farnesyltransferase inhibitors, the conformational diversity of the peptide is only considered for the last 5 residues. This simplification of the peptide is carried out in order to compare the conformational profiles of Hoe 140 and the group of bradykinin analogs presented in the second part of the chapter: 5-residue long peptides containing 1-amino-2-phenylclyclopropanecarboxylic acid, a conformationally restricted residue. Finally, chapters 4 and 5 are dedicated to an 11-residue neuropeptide: substance P. The increase in size provoked a change in the methodology. Indeed, the conformational profile of the peptide has been studied by means of iterative simulated annealing and extensive molecular dynamics trajectories. This has permitted the comparison between both methodologies and to derive conclusions to the kind of information that can be obtained through these different methodologies for the exploration of the conformational space of peptides.The present work has been partially published through two papers:F.J Corcho, M. Filizola, J.J. Pérez. Evaluation of the iterative simulated annealing technique in conformational search of peptides. Chemical Physics Letters. 2000, 319: 65-70.F.J. Corcho, M. Filizola y J.J. Pérez. Assessment of the bioactive conformation of the farnesyltransferase protein binding recognition motif by computational methods.Journal of Biomolecular Structure and Dynamics. 1999, 16(5): 1043-1052. / El present treball està dedicat a l'exploració de l'espai conformacional de pèptids biològicament actius, sota diferent condicions, amb l'objectiu de caracteritzar el seu perfil conformacional. S'han usat diferents tècniques dins del marc de la mecànica molecular. Un primer obstacle a l'inici d'aquest treball va ser la definició d'un criteri per mesurar com d'exhaustiu havia estat i quan s'havia d'aturar la cerca. Al segon capítol es presenta una solució a aquest problema per al recuit simulat iteratiu.La determinació de la conformació bioactiva és un requeriment per al disseny de peptidomimetics assistit per ordinador. La conformació bioactiva pot ser simplificada prenent els grups funcionals que se sap que interactuen amb el receptor i la distància relativa entre aquests grups. Aquesta entitat esquemàtica és anomenada farmacòfor. El farmacòfor pot ésser utilitzat per cribar bases de dades tridimensionals de molècules per a la cerca de peptidomimètics. A continuació, per als compostos obtinguts en la cerca es pot testar la seva activitat i identificar així un nou grup de caps de sèrie. Al capítol 3 es descriu un exemple d'aquest procediment que té com a objectiu l'obtenció d'un nou grup d'antagonistes de la bradiquinina.Els pèptids han sigut tradicionalment considerats molècules flexibles especialment en solvents polars com l'aigua. La flexibilitat és difícil de mesurar mitjançant tècniques experimentals i com a conseqüència els pèptids han sigut considerats molècules que no presentaven estructura sota aquestes condicions. Per una altra banda els pèptids biològicament actius se sap que interactuen amb els seus receptors a través d'una conformació preferida, sovint anomenada conformació bioactiva. La hipòtesi més acceptada per explicar la interacció dels pèptids i els seus receptors és l'ajustament induït o "induced fit". Així, el pèptid mostrarà en solució motius conformacionals que són part de la conformació adoptada al receptor. Posteriorment a la unió del pèptid al receptor, la conformació en solució serà modificada de manera que s'optimitzi la interacció del pèptid i el receptor. Per tant, sembla existir una contradicció entre la necessitat de que hi hagi un cert grau d'estructura en el pèptid prèviament a la unió al receptor i la manca d'estructura del pèptid en solució. En alguns casos s'ha argumentat que la unió del pèptid a la membrana biològica és un prerequisit per a l'adopció de la conformació bioactiva i la subsegüent unió al receptor. Als capítols 4 i 5 aquesta hipòtesi és criticada i es presenta una hipòtesi alternativa.Recentment, s'han presentat diferent exemples de plegament de pèptids que han sigut simulats mitjançant llargues trajectòries de dinàmica molecular. Sorgeix un problema quan la gran diversitat de conformacions obtingudes ha de ser classificada en termes del seu grau de plegament respectiu. Al capítol 4 es descriu una nova metodologia per a la classificació i l'agrupament d'estructures peptídiques basades en la presència de motius estructurals i les similituds entre elles. Aquesta metodologia pot resultar molt útil ja que és gairebé automàtica i no presenta cap tipus de limitació respecte al tamany del pèptid o la proteïna en estudi.Per tal de seguir els problemes que apareixen quan la mida i la flexibilitat dels pèptids s'incrementen, la seqüència dels capítols d'aquest estudi es presenta amb mida dels pèptids creixent. Així, al capítol 2 el perfil conformacional dels inhibidors de la farnesiltransferasa que tenen una llargària de 4 residus és estudiat mitjançant el procés de recuit simulat iteratiu. La primera part del capítol 3 tracta amb un antagonista de la bradiquinina, Hoe 140. Malgrat que Hoe 140 amb 10 residus és més gran que els inhibidors de la farnesiltransferasa, que tenen 4 residus, la diversitat conformacional del pèptid només s'ha considerat pels darrers 5 residus. Aquesta simplificació del pèptid es realitza per tal de comparar el perfils conformationals de Hoe 140 i d'un grup d'anàlegs de la bradiquinina, que es presenten a la segona part del capítol, de 5 residus de llargària i que contenen l'àcid 1-amino-2-fenilciclopropacarboxílic que és un residu conformacionalment restringit. Finalment, els capítols 4 i 5 estan dedicats a un neuropèptid d'onze residus: substància P. L'increment de la mida va provocar un canvi en la metodologia emprada. Així, el perfil conformacional del pèptid ha sigut estudiat mitjançant el recuit simulat iteratiu i mitjançant trajectòries extenses de dinàmica molecular. Això ha permès la comparació entre ambdues metodologies i l'extracció de conclusions sobre el tipus d'informació que pot obtenir-se a través de les diferents metodologies per a l'exploració de l'espai conformacional de pèptids.El present treball s'ha publicat parcialment a dos articles:F.J Corcho, M. Filizola, J.J. Pérez. Evaluation of the iterative simulated annealing technique in conformational search of peptides. Chemical Physics Letters. 2000, 319: 65-70.F.J. Corcho, M. Filizola y J.J. Pérez. Assessment of the bioactive conformation of the farnesyltransferase protein binding recognition motif by computational methods.Journal of Biomolecular Structure and Dynamics. 1999, 16(5): 1043-1052. / de la Tesis DoctoralEl presente trabajo está dedicado a la exploración del espacio conformacional de pèptids biológicamente activos, bajo diferentes condiciones, i con el objetivo de caracterizar su perfil conformacional. Se han usado diferentes técnicas dentro del marco de la mecánica molecular. Un primer obstáculo al inicio de este trabajo fue la definición de un criterio para medir como de exhaustivo había sido y cuando se debía detener la búsqueda. En el segundo capítulo se presenta una solución a este problema para al recocido simulado iterativo.La determinación de la conformación bioactiva es un requerimiento para al diseño de peptidomiméticos asistido por ordenador. La conformación bioactiva puede ser simplificada tomando los grupos funcionales que se sabe que interactúan con el receptor y la distancia relativa entre estos grupos. Esta entidad esquemática es llamada farmacóforo. El farmacóforo puede ser utilizado para cribar bases de datos tridimensionales de moléculas para la búsqueda de peptidomiméticos. A continuación, para los compuestos obtenidos en la búsqueda se puede testar la actividad e identificar así un nuevo grupo de cabezas de serie. En el capítulo 3 se describe un ejemplo de este procedimiento que tiene como objetivo la obtención de un nuevo grupo de antagonistas de la bradiquinina.Los péptidos han sido tradicionalmente considerados moléculas flexibles especialmente en solventes polares como el agua. La flexibilidad es difícil de medir mediante técnicas experimentales y como consecuencia los péptidos han sido considerados moléculas que no presentaban estructura bajo estas condiciones. Por otra parte los péptidos biológicamente activos se sabe que interactúan con sus receptores a través de una conformación preferida, a menudo llamada conformación bioactiva. La hipótesis más aceptada para explicar la interacción de los péptidos y sus receptores es el ajuste inducido o "induced fit". Así, el péptid mostrará en solución motivos conformacionales que son parte de la conformación adoptada en el receptor. Posteriormente a la unión del péptido al receptor, la conformación en solución será modificada de manera que se optimice la interacción del péptido y el receptor. Por tanto, parece existir una contradicción entre la necesidad de que haya un cierto grado de estructura en el péptido previamente a la unión al receptor y la ausencia de estructura del péptido en solución. En algunos casos se ha argumentado que la unión del péptido a la membrana biológica es un prerrequisito para la adopción de la conformación bioactiva y la subsiguiente unión al receptor. En los capítulos 4 i 5 esta hipótesis es criticada y se presenta una hipótesis alternativa.Recientemente, se han presentado diferentes ejemplos de plegamiento de péptidos que han sido simulados mediante largas trayectorias de dinámica molecular. Surge un problema cuando la gran diversidad de conformaciones obtenidas ha de ser clasificada en términos de su grado de plegamiento respectivo. En el capítulo 4 se describe una nueva metodología para la clasificación y el agrupamiento de estructuras peptídicas basadas en la presencia de motivos estructurales y las similitudes entre ellas. Esta metodología puede resultar muy útil ya que está casi automatizada y no presenta ningún tipo de limitación respecto al tamaño del péptido o la proteína en estudio.Con el objetivo de seguir los problemas que aparecen cuando la medida y la flexibilidad de los péptidos se incrementan, la secuencia de los capítulos de este estudio se presenta con la medida de los péptidos creciente. Así, en el capítulo 2 el perfil conformacional de los inhibidores de la farnesiltransferasa que tienen una longitud de 4 residuos es estudiado mediante el proceso del recocido simulado iterativo. La primera parte del capítulo 3 trata con un antagonista de la bradiquinina, Hoe 140. Aunque Hoe 140 con 10 residuos es más grande que los inhibidores de la farnesiltransferasa, que tienen 4 residuos, la diversidad conformacional del péptido solo se ha considerado para los últimos 5 residuos. Esta simplificación del péptido se realiza por tal de comparar los perfiles conformationales de Hoe 140 y de un grupo de análogos de la bradiquinina, que se presentan en la segunda parte del capítulo, de 5 residuos de longitud y que contienen el ácido 1-amino-2-fenilciclopropacarboxílico que es un residuo conformacionalmente restringido. Finalmente, los capítulos 4 y 5 están dedicados a un neuropéptido de once residuos: sustancia P. El incremento de la medida provocó un cambio en la metodología utilizada. Así, el perfil conformacional del péptido ha sido estudiado mediante el recocido simulado iterativo y mediante trayectorias extensas de dinámica molecular. Esto ha permitido la comparación entre ambas metodologías y la extracción de conclusiones sobre el tipo de información que se puede obtener a través de las diferentes metodologías para la exploración del espacio conformacional de péptidos.El presente trabajo se ha publicado parcialmente en dos artículos:F.J Corcho, M. Filizola, J.J. Pérez. Evaluation of the iterative simulated annealing technique in conformational search of peptides. Chemical Physics Letters. 2000, 319: 65-70.F.J. Corcho, M. Filizola y J.J. Pérez. Assessment of the bioactive conformation of the farnesyltransferase protein binding recognition motif by computational methods.Journal of Biomolecular Structure and Dynamics. 1999, 16(5): 1043-1052.

Estimating human motion is the topic of this thesis. We are interested in accurately estimating the motion of a human body using only video images capturing the subject in motion. Video images from up to two cameras are considered. The first main topic of the thesis is to investigate a new type of input data. This data consists of some sort of texture. This texture can be added to the human body segment under study or it can be the actual texture of the skin. In paper I we investigate if added texture together with the use of a two camera system can provide enough information to make it possible to estimate the knee joint center location. Evaluation is made using a marker based system that is run in parallel to the two camera video system. The results from this investigation show promise for the use of texture. The marker and texture based estimates differ in absolute values but the variations are similar indicating that texture is in fact usable for this purpose. In paper II and III we investigate further the usability in images of skin texture as input for motion estimation. Paper II approaches the problem of estimating human limb motion in the image plane. An image histogram based mutual information criterion is used to decide if an extracted image patch from frame k is a good match to some location in frame k+1. Eval- uation is again performed using a marker based system synchronized to the video stream. The results are very promising for the application of skin texture based motion estimation in 2D. In paper III, basically the same approach is taken as in paper II with the substantial difference that here estimation of three dimensional motion is addressed. Two video cameras are used and the image patch matching is performed both between cameras (inter-camera) in frame k and also in each cameras images (intra-camera) for frame k to k+1. The inter-camera matches yield triangulated three dimensional estimates on the approximate surface of the skin. The intra-camera matches provide a way to connect the three dimensional points between frame k and k+1 The resulting one step three dimensional trajectories are then used to estimate rigid body motion using least squares methods. The results show that there is still some work to be done before this texture based method can be an alternative to the marker based methods. In paper IV the second main topic of the thesis is discussed. Here we present an investigation in using model based techniques for the purpose of estimating human motion. A kinematic model of the thigh and shank segments are built with an anatomic model of the knee. Using this model, the popular particle filter and typical simulated data from the triangulation in paper III, an estimate of the motion variables in the thigh and shank segment can be achieved. This also includes one static model parameter used to describe the knee model. The results from this investigation show good promise for the use of triangulated skin texture as input to such a model based approach.

This Thesis Work will concentrate on a very interesting problem, the Vehicle Routing Problem (VRP). In this problem, customers or cities have to be visited and packages have to be transported to each of them, starting from a basis point on the map. The goal is to solve the transportation problem, to be able to deliver the packages-on time for the customers,-enough package for each Customer,-using the available resources- and – of course - to be so effective as it is possible.Although this problem seems to be very easy to solve with a small number of cities or customers, it is not. In this problem the algorithm have to face with several constraints, for example opening hours, package delivery times, truck capacities, etc. This makes this problem a so called Multi Constraint Optimization Problem (MCOP). What’s more, this problem is intractable with current amount of computational power which is available for most of us. As the number of customers grow, the calculations to be done grows exponential fast, because all constraints have to be solved for each customers and it should not be forgotten that the goal is to find a solution, what is best enough, before the time for the calculation is up. This problem is introduced in the first chapter: form its basics, the Traveling Salesman Problem, using some theoretical and mathematical background it is shown, why is it so hard to optimize this problem, and although it is so hard, and there is no best algorithm known for huge number of customers, why is it a worth to deal with it. Just think about a huge transportation company with ten thousands of trucks, millions of customers: how much money could be saved if we would know the optimal path for all our packages.Although there is no best algorithm is known for this kind of optimization problems, we are trying to give an acceptable solution for it in the second and third chapter, where two algorithms are described: the Genetic Algorithm and the Simulated Annealing. Both of them are based on obtaining the processes of nature and material science. These algorithms will hardly ever be able to find the best solution for the problem, but they are able to give a very good solution in special cases within acceptable calculation time.In these chapters (2nd and 3rd) the Genetic Algorithm and Simulated Annealing is described in details, from their basis in the “real world” through their terminology and finally the basic implementation of them. The work will put a stress on the limits of these algorithms, their advantages and disadvantages, and also the comparison of them to each other.Finally, after all of these theories are shown, a simulation will be executed on an artificial environment of the VRP, with both Simulated Annealing and Genetic Algorithm. They will both solve the same problem in the same environment and are going to be compared to each other. The environment and the implementation are also described here, so as the test results obtained.Finally the possible improvements of these algorithms are discussed, and the work will try to answer the “big” question, “Which algorithm is better?”, if this question even exists.

Commercial pure terephthalic acid (PTA) manufacturing generates process streams mainly containing acetic acid (HAc) and water. A large financial incentive exists to replace the costly and energy intensive distillation column used to recycle HAc-water mixtures. This work focuses on the development of pervaporation technology to separate HAc-water mixtures using a hollow fiber-based membrane unit. Currently a 250 m outer diameter Matrimid® hollow fiber is used in industry for gas separation. Due to the difference between gas and liquid separations, the fiber performance associated with high flux in pervaporation is limited by a pressure change inside the bore along the axial direction of the fiber. A mathematical model was developed to describe the bore pressure change in pervaporation in this work, which demonstrated that spinning a large bore size fiber was a good solution to minimize the bore pressure change. Spinning technology has been adapted to obtain a large bore size defect-free Matrimid® hollow fiber. In addition to a large bore size, the asymmetric fiber exhibits an intrinsically defect-free selective layer supported on an open porous substrate. This eliminates the post-treatment with a caulking layer and has a special advantage for aggressive liquid separation. A proof of concept was provided by testing both small and large bore size defect-free fibers with a model 20% wt HAc feed in a pervaporation system at 101.5oC. The membrane selectivity (~ 25) and water flux (~ 4.5 kg/m2hr) were increased by about 150% with a diameter (O.D. ~ 500 m) twice as large as the regular fiber. Further, a decrease in the HAc flux was observed with the increased bore size due to the reduction in HAc-induced plasticization. Sub-Tg thermal annealing was used to stabilize the fiber by suppressing HAc-induced plasticization. This improves the polymer discrimination of shape and size for penetrants although no chemical reaction occurs with thermal annealing. The resulting membrane selectivity was increased from 10 to about 95 using a large bore size defect-free annealed fiber with acceptable water flux (~ 1.5 kg/m2hr) for 20% wt HAc concentration feed streams. These improvements make Matrimid® hollow fiber membranes very attractive for future scale-up and commercial development.

This dissertation investigates the development of a methodology suitable for the evaluation of advanced propulsion concepts. At early stages of development, both the future performance of these concepts and their requirements are highly uncertain, making it difficult to forecast their future value. A systematic methodology to identify potential advanced propulsion concepts and assess their robustness is necessary to reduce the risk of developing advanced propulsion concepts. Existing advanced design methodologies have evaluated the robustness of technologies or concepts to variations in requirements, but they are not suitable to evaluate a large number of dissimilar concepts. Variations in requirements have been shown to impact the development of advanced propulsion concepts, and any method designed to evaluate these concepts must incorporate the possible variations of the requirements into the assessment. In order to do so, a methodology had to do two things. First, it had to systemically identify a probabilistic distribution for the future requirements. Such a distribution would allow decision-makers to quantify the uncertainty introduced by variations in requirements. Second, the methodology must assess the robustness of the propulsion concepts as a function of that distribution. These enabling elements have been synthesized into new methodology, the Evolving Requirements Technology Assessment (ERTA) method. The ERTA method was used to evaluate and compare advanced propulsion systems as possible power systems for a hurricane tracking, High Altitude, Long Endurance (HALE) unmanned aerial vehicle (UAV). The problem served as a good demonstration of the ERTA methodology because conventional propulsion systems will not be sufficient to power the UAV, but the requirements for such a vehicle are still uncertain.

This thesis is concerned with identifying the best decision among a set of possible decisions in the presence of uncertainty. We are primarily interested in situations where the objective function value at any feasible solution needs to be estimated, for example via a ``black-box' simulation procedure. We develop adaptive random search methods for solving such simulation optimization problems. The methods are adaptive in the sense that they use information gathered during previous iterations to decide how simulation effort is expended in the current iteration. We consider random search because such methods assume very little about the structure of the underlying problem, and hence can be applied to solve complex simulation optimization problems with little expertise required from an end-user. Consequently, such methods are suitable for inclusion in simulation software. We first identify desirable features that algorithms for discrete simulation optimization need to possess to exhibit attractive empirical performance. Our approach emphasizes maintaining an appropriate balance between exploration, exploitation, and estimation. We also present two new and almost surely convergent random search methods that possess these desirable features and demonstrate their empirical attractiveness. Second, we develop two frameworks for designing adaptive and almost surely convergent random search methods for discrete simulation optimization. Our frameworks involve averaging, in that all decisions that require estimates of the objective function values at various feasible solutions are based on the averages of all observations collected at these solutions so far. We present two new and almost surely convergent variants of simulated annealing and demonstrate the empirical effectiveness of averaging and adaptivity in the context of simulated annealing. Finally, we present three random search methods for solving simulation optimization problems with uncountable feasible regions. One of the approaches is adaptive, while the other two are based on pure random search. We provide conditions under which the three methods are convergent, both in probability and almost surely. Lastly, we include a computational study that demonstrates the effectiveness of the methods when compared to some other approaches available in the literature.