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type:Conference Paper, We demonstrate a precision time protocol (PTP) used to synchronize clocks in industrial wireless local area network (iWLAN) communication systems. The implementation of the system on FPGA boards for accurate verification and to test the feasibility of the system in a real environment. The result has been confirmed that time synchronization is high accuracy from 40 to 100 ns., IEEE International Symposium on Circuits and Systems (ISCAS 2019), May 26-29, 2019, Sapporo Japan, source:DOI:10.1109/ISCAS.2019.8702192

Работа посвящена исследованию методов технического анализа финансовых рынков. Глобализация и развитие информационных технологий привели к увеличению оборота валютного рынка. Современные вычислительные средства позволяют решать любые проблемы, связанные с анализом больших объемов данных. Поэтому актуален технический аспект при построении торговой стратегии. Технический анализ - это торговая дисциплина, используемая для оценки ценных бумаг и определения торговых возможностей путем анализа статистических данных, полученных от торговой деятельности, таких как движение цены и объема. Важной частью технического анализа являются паттерны японских свечей. Паттерны японских свечей - это технический инструмент, который собирает данные за несколько временных рамок в отдельные ценовые бары. В статье рассмотрены основные паттерны японских свечей, относящиеся к моделям разворота тенденции. Выполнена формализация рассмотренных паттернов – предложены формульные выражения для дальнейшей автоматизации процесса поиска паттернов. Реализованы полученные модели в виде индикатора для торговой платформы cTrader с использованием объектно-ориентированного языка программирования C #.. Показаны результаты исследований работы разработанного индикатора. В статье рассмотрены основные паттерны японских свечей, относящиеся к моделям разворота тенденции, выполнена формализация рассмотренных паттернов, а также реализация полученных моделей в виде индикатора для торговой платформы cTrader. Показаны результаты работы разработанного индикатора., The relevance of foreign exchange markets is due to their high liquidity. Globalization and development of information technologies led to increase in foreign exchange market’s turnover. Modern computing facilities allow us to solve any problems associated with the analysis of large data volumes. That’s why the major part of speculative investors focuses on technical aspect while building their trading strategy. Technical analysis is a trading discipline employed to evaluate securities and identify trading opportunities by analyzing statistics gathered from trading activity, such as price movement and volume. An important part of technical analysis are Japanese candlestick patterns. Japanese candlestick patterns are a technical tool that pack data for multiple time frames into single price bars. This makes them more useful than traditional open-high, low-close bars or simple lines that connect the dots of closing prices. Candlesticks build patterns that predict price direction once completed. They are conditionally divided into reversal and continuation patterns. The article presents the investigation of methods of technical analysis of financial markets. In the article the main reversal Japanese candlestick patterns are considered. These patterns are formalized and realized using the trading platform cTrader using the object-oriented programming language C#.

The Proceedings summarizes the 12 lectures that have taken place within the ILIAS Dinstguished Lecture series 2017. It contains a brief abstract of the talks as well as some additional information about each speaker.

Frequent pattern mining is the process of mining data in a set of items or some patterns from a largedatabase. The resulted frequent set data supports the minimum support threshold. A frequentpattern is a pattern that occurs frequently in a dataset. Association rule mining is defined as to findout association rules that satisfy the predefined minimum support and confidence from a given database. If an item set is said to be frequent, that item set supports the minimum support andconfidence. A Frequent item set should appear in all the transaction of that data base. Discoveringfrequent item sets play a very important role in mining association rules, sequence rules, web logmining and many other interesting patterns among complex data. Data stream is a real timecontinuous, ordered sequence of items. It is an uninterrupted flow of a long sequence of data. Somereal time examples of data stream data are sensor network data, telecommunication data,transactional data and scientific surveillances systems. These data produced trillions of updatesevery day. So it is very difficult to store the entire data. In that time some mining process is required.Data mining is the non-trivial process of identifying valid, original, potentially useful and ultimatelyunderstandable patterns in data. It is an extraction of the hidden predictive information from largedata base. There are lots of algorithms used to find out the frequent item set. In that Apriorialgorithm is the very first classical algorithm used to find the frequent item set. Apart from Apriori,lots of algorithms generated but they are similar to Apriori. They are based on prune and candidategeneration. It takes more memory and time to find out the frequent item set. In this paper, we havestudied about how the éclat algorithm is used in data streams to find out the frequent item sets.Éclat algorithm need not required candidate generation.

Communities are a fundamental structure in social organizations. It is not surprising, then, that there have been multiple attempts at modeling them in order to better understand the architecture of our civilization. Usually, these models are based on online Social Networks, which provide incredibly valuable data about communities that are believed to be significantly similar to real-life communities. Large scale models have provided insight in several macroscopic properties of these networks. There is, however, very little work on the microscopic properties of communities and their role in Social Networks, leaving an important research gap that is being fulfilled during recent years. The objective of this thesis is come up with this kind of hypotheses and analyse their role in a mathematical model., Outgoing

Idle speed control is investigated for a direct injection, spark ignition, stratified charge (DISC) engine equipped with an electronic throttle. Such engines can be operated in multiple combustion modes. When operating in stratified charge combustion mode, they are very different from conventional stoichiometric engines, creating new opportunities for improved speed control. With current after-treatment technology, simultaneous high fuel economy and emissions conversion efficiency cannot be achieved by operating the engine in a steady-state manner: it must be cycled between running ultra-lean (for fuel economy) and rich (to service the after-treatment system). An idle speed control system is designed to meet the considerable feedback control demands required by these new engines. Copyright © 2001 John Wiley & Sons, Ltd.

In its basic version, Petri Nets are defined as fixed graphs, where thebehaviour of the system is modelled as the marking of the graph which changes overtime. This constraint makes the Petri Nets a poor tool to deal with reconfigurablesystems as mobile computing systems, where the structure of the system can changeas its behaviour, during time. Many extended Petri nets were proposed to deal withthis weakness. The aim of this work is to present a new extension of Petri Nets, wherethe structure of the graph can be highly flexible. This flexibility gives a rich modelwith complex behaviours, not allowed in previous extensions. The second aim is toprove that even these behaviours are so complex; they can be translated into otherlow level models (as Coloured Petri Nets [21]) and so be analysed. This translationexploits Dynamic Petri Nets [11] as an intermediary representation between our modeland Coloured Petri Nets.

Monterey Phoenix (MP) is an approach to formal software system architecture specification based on behavior models. Architecture modeling focuses not only on the activities and interactions within the system, but also on the interactions between the system and its environment, providing an abstraction for interaction specification. The behavior of the system is defined as a set of events (event trace) with two basic relations: precedence and inclusion. The structure of possible event traces is specified using event grammars and other constraints organized into schemas. The separation of the interaction description from the components behavior is an essential MP feature. The schema framework is amenable to stepwise architecture refinement, reuse, composition, visualization, and multiple view extraction. The approach yields a basis for executable architecture specification supporting early testing and verification, systematic use case generation, and performance estimates with automated tools.

To promote reproducibility, since 2009 all my empirical research has been cached in a data repository that captures all source code and data dependencies automatically or semi-automatically. Our principle goals are to modularize, document, and preserve all aspects of experimental data. So that others may benefit from or adapt my methods, I provide a bit of motivation and explanation here, along with the full description of the parameters and guidelines of the data repository (provided to my research students) and source code for the utilities.

We investigate the Robust Deviation Balanced Minimum Evolution Problem (RDBMEP), a combinatorial optimization problem that arises in computational biology when the evolutionary distances from taxa are uncertain and varying inside intervals. By exploiting some fundamental properties of the objective function, we present a mixed integer programming model to exactly solve instances of the RDBMEP and discuss the biological impact of uncertainty on the solutions to the problem. Our results give perspective on the mathematics of the RDBMEP and suggest new directions to tackle phylogeny estimation problems affected by uncertainty.

A loss of heterozygosity (LOH) event occurs when, by the laws of Mendelian inheritance, an individual should be heterozygote at a given site but, due to a deletion polymorphism, is not. Deletions play an important role in human disease and their detection could provide fundamental insights for the development of new diagnostics and treatments. In this paper, we investigate the parsimonious loss of heterozygosity problem (PLOHP), i.e., the problem of partitioning suspected polymorphisms from a set of individuals into a minimum number of deletion areas. Specifically, we generalize Halldórsson et al.'s work by providing a more general formulation of the PLOHP and by showing how one can incorporate different recombination rates and prior knowledge about the locations of deletions. Moreover, we show that the PLOHP can be formulated as a specific version of the clique partition problem in a particular class of graphs called undirected catch-point interval graphs and we prove its general $({\cal NP})$-hardness. Finally, we provide a state-of-the-art integer programming (IP) formulation and strengthening valid inequalities to exactly solve real instances of the PLOHP containing up to 9,000 individuals and 3,000 SNPs. Our results give perspectives on the mathematics of the PLOHP and suggest new directions on the development of future efficient exact solution approaches.

The United States is engaged in a new type of warfare. Defeating the enemy is now predicated on winning over local populations. To win these groups, commanders need to know what responses to expect for various operations in particular locations. Social simulations are a promising means of modeling these reactions, and there are several current methods used to populate these simulations with agents representative of a specific society. These methods, however, often require the input of subject matter experts and are costly in price and time. This thesis examines the simplification and automation of the agent instantiation process by conducting a usability study of two data development tools currently under consideration by the U.S. Army and TRAC-MTRY. The tools, a survey data case file generator developed at TRAC-MTRY and a text analysis tool (STANLEY) developed by Sandia National Laboratory, were examined in separate manners, and the results were encouraging. The survey tool was tested to validate in a practical manner its generated case files with respect to simulation output and real-world surveys. STANLEY was evaluated by scoring sentiment in a document corpus and attempting to correlate those scores to a real world issue. Results of the study indicate that the survey data tool generated case files of adequate quality to instantiate social simulations, potentially minimizing SME requirements and costs. Technical limitations precluded STANLEY from returning enough data for sufficient correlation comparison, although the results indicate the tool has potential., http://archive.org/details/comparisonofdatd109455566, Approved for public release; distribution is unlimited.

This thesis was performed at the MOVES Institute, The Marine Corps is assessing how shooters train for Combat Marksmanship. An implementation of the Rifle Combat Optics (RCO) has been introduced into the Annual Rifle Qualification requirement. The question now is, How do coaches modify training to effectively instruct the shooters in firing with the RCO? This study provides feedback using the Split Shot Scope System as an aid in training doctrinal techniques for marksmanship on live fire ranges. The assessments, provided by current Marine Corps Marksmanship Instructors, highlight a necessity to using a device such as the Split Shot Scope System. In a postsurvey conducted in the study, responses provide a viable path to employing this diagnostic tool during live fire shooting and reporting the level of utility of this device. Added, in this study, is the use of a sensor package derived from concepts of the Indoor Simulated Marksmanship Trainer (ISMT), which will be discussed to provide the utility of such a device for improving and defining a useful technique for training shooters. While this may not be a complete fix to the dilemma, this study has provided an approach to understanding and deriving methods for effective marksmanship training and diagnosing fundamental problems more clearly., http://archive.org/details/identifyingmetho109455607, Approved for public release; distribution is unlimited.

Firefighting Training at San Diego location is very effective, valuable, and beneficial to ships crews and the U.S. Navy., http://archive.org/details/evaluationofmode109455534, Approved for public release; distribution is unlimited.

A phylogeny is an unrooted binary tree that represents the evolutionary relationships of a set of n species. Phylogenies find applications in several scientific areas ranging from medical research, to drug discovery, to epidemiology, to systematics, and to population dynamics. In such applications the available information is usually restricted to the leaves of a phylogeny and is represented by molecular data extracted from the analyzed species, such as DNA, RNA, amino acid or codon fragments. On the contrary, the information about the phylogeny itself is generally missing and is determined by solving an optimization problem, called the Phylogeny Estimation Problem (PEP), whose versions depend on the criterion used to select a phylogeny from among plausible alternatives. In this article we investigate a recent version of the PEP, called the Balanced Minimum Evolution Problem (BMEP). We present a mixed integer linear programming model to solve exactly instances of the BMEP and develop branching rules and families of valid inequalities to further strengthen the model. Our results give perspective on the mathematics of the BMEP and suggest new directions on the development of future efficient exact approaches to solution of the problem.

We introduce the Partitioning-Hub-Location-Routing Problem (PHLRP), a hub location problem involving graph partitioning and routing features. The PHLRP consists of partitioning a given network into sub-networks, locating at least one hub in each sub-network and routing the traffic within the network at minimum cost. This problem finds applications in deployment of an Internet Routing Protocol called Intermediate System–Intermediate System (ISIS), and strategic planning of LTL ground freight distribution systems. We present an Integer Programming (IP) model for solving exactly the PHLRP and explore possible valid inequalities to strengthen it. Computational experiments prove the effectiveness of our model which is able to tackle instances of PHLRP containing up to 20 vertices.

We investigate the uncertain versions of two classical combinatorial optimization problems, namely the Single-Pair Shortest Path Problem (SP-SPP) and the Single-Source Shortest Path Problem (SS-SPP). The former consists of finding a path of minimum length connecting two specific nodes in a finite directed graph G; the latter consists of finding the shortest paths from a fixed node to the remaining nodes of G. When considering the uncertain versions of both problems we assume that cycles may occur in G and that arc lengths are (possibly degenerating) nonnegative intervals. We provide sufficient conditions for a node and an arc to be always or never in an optimal solution of the Minimax regret Single-Pair Shortest Path Problem (MSP-SPP). Similarly, we provide sufficient conditions for an arc to be always or never in an optimal solution of the Minimax regret Single-Source Shortest Path Problem (MSS-SPP). We exploit such results to develop pegging tests useful to reduce the overall running time necessary to exactly solve both problems.

The thermal conductivity of self-organized quantum dot (QD) active regions is estimated by measurements of wavelength chirp with injected current as a function of the current pulse duty cycle both below and above threshold. A simple model which separates out thermal and charge carrier chirps is used to estimate the thermal conductivity of the QD active region. With this model, the thermal conductivity of the InGaAs QD active region is estimated to be ??? 0.1???W/m???K???0.1W???mK, about two orders of magnitude less than that of the bulk material. This is consistent with theoretical predictions of the reduced thermal conductivity of QD regions.

A method for generating large???amplitude nonlinear plasma waves, which utilizes an optimized train of independently adjustable, intense laser pulses, is analyzed in one dimension both theoretically and numerically (using both Maxwell???fluid and particle???in???cell codes). Optimal pulse widths and interpulse spacings are computed for pulses with either square or finite???rise???time sine shapes. A resonant region of the plasma wave phase space is found where the plasma wave is driven most efficiently by the laser pulses. The width of this region, and thus the optimal finite???rise???time laser pulse width, was found to decrease with increasing background plasma density and plasma wave amplitude, while the nonlinear plasma wavelength, and thus the optimal interpulse spacing, increases. Also investigated are damping of the wave by trapped background electrons, and the sensitivities of the resonance to variations in the laser and plasma parameters. Resonant excitation is found to be superior for electron acceleration to either beatwave or single???pulse excitation because comparable plasma wave amplitudes may be generated at lower plasma densities, reducing electron???phase detuning, or at lower laser intensities, reducing laser???plasma instabilities. Practical experimental methods for producing the required pulse trains are discussed. ??1996 American Institute of Physics.

Resolution and covariance predictors have been derived previously for penalized-likelihood estimators. These predictors can provide accurate approximations to the local resolution properties and covariance functions for tomographic systems given a good estimate of the mean measurements. Although these predictors may be evaluated iteratively, circulant approximations are often made for practical computation times. However, when numerous evaluations are made repeatedly (as in penalty design or calculation of variance images), these predictors still require large amounts of computing time. In Stayman and Fessler (2000), we discussed methods for precomputing a large portion of the predictor for shift-invariant system geometries. In this paper, we generalize the efficient procedure discussed in Stayman and Fessler (2000) to shift-variant single photon emission computed tomography (SPECT) systems. This generalization relies on a new attenuation approximation and several observations on the symmetries in SPECT systems. These new general procedures apply to both two-dimensional and fully three-dimensional (3-D) SPECT models, that may be either precomputed and stored, or written in procedural form. We demonstrate the high accuracy of the predictions based on these methods using a simulated anthropomorphic phantom and fully 3-D SPECT system. The evaluation of these predictors requires significantly less computation time than traditional prediction techniques, once the system geometry specific precomputations have been made.

The United States is engaged in a new type of warfare. Defeating the enemy is now predicated on winning over local populations. To win these groups, commanders need to know what responses to expect for various operations in particular locations. Social simulations are a promising means of modeling these reactions, and there are several current methods used to populate these simulations with agents representative of a specific society. These methods, however, often require the input of subject matter experts and are costly in price and time. This thesis examines the simplification and automation of the agent instantiation process by conducting a usability study of two data development tools currently under consideration by the U.S. Army and TRAC-MTRY. The tools, a survey data case file generator developed at TRAC-MTRY and a text analysis tool (STANLEY) developed by Sandia National Laboratory, were examined in separate manners, and the results were encouraging. The survey tool was tested to validate in a practical manner its generated case files with respect to simulation output and real-world surveys. STANLEY was evaluated by scoring sentiment in a document corpus and attempting to correlate those scores to a real world issue. Results of the study indicate that the survey data tool generated case files of adequate quality to instantiate social simulations, potentially minimizing SME requirements and costs. Technical limitations precluded STANLEY from returning enough data for sufficient correlation comparison, although the results indicate the tool has potential.

The Marine Corps is assessing how shooters train for Combat Marksmanship. An implementation of the Rifle Combat Optics (RCO) has been introduced into the Annual Rifle Qualification requirement. The question now is, How do coaches modify training to effectively instruct the shooters in firing with the RCO? This study provides feedback using the Split Shot Scope System as an aid in training doctrinal techniques for marksmanship on live fire ranges. The assessments, provided by current Marine Corps Marksmanship Instructors, highlight a necessity to using a device such as the Split Shot Scope System. In a postsurvey conducted in the study, responses provide a viable path to employing this diagnostic tool during live fire shooting and reporting the level of utility of this device. Added, in this study, is the use of a sensor package derived from concepts of the Indoor Simulated Marksmanship Trainer (ISMT), which will be discussed to provide the utility of such a device for improving and defining a useful technique for training shooters. While this may not be a complete fix to the dilemma, this study has provided an approach to understanding and deriving methods for effective marksmanship training and diagnosing fundamental problems more clearly.

Firefighting Training at San Diego location is very effective, valuable, and beneficial to ships crews and the U.S. Navy.

We present an integer programming model for human leukocyte antigen (HLA) association studies based on the parsimony criterion. The model is simple, compact, easy to implement, and able to handle datasets containing up to 200 phenotypes. Computational experiments carried out on patients affected by psoriasis and severe alopecia areata show that the model is consistent with the experimental haplotype frequencies, showing, for the considered diseases at least, a high reliability of the predictions. These promising results provide perspective on computer-aided association studies and encourage the development of efficient exact computational approaches for haplotype estimation.

Much progress has been made in recent years in solving certain classes of production planning problems using mixed integer programming. One of the major challenges is how to make this expertise available and easy to use to the non-specialist and to the practitioners. Here we describe a modeling approach and tool LS-LIB, and report on computational results. LS-LIB is a library of primitives to declare procedures/subroutines/global constraints in a high-level modeling language that we believe offers an interesting partial answer to this challenge. LS-LIB provides routines for problem reformulation, cut generation, and heuristics to find good feasible solutions quickly. The user must provide an initial formulation of his problem in the modeling language MOSEL. Then using his knowledge of the problem he must first classify each product or sku according to a simple three field scheme: [production type, capacity type, variant] proposed recently. Then it is a simple matter to use the global constraints of LS-LIB by adding a few lines to his initial MOSEL formulation to get a tightened formulation and/or call the appropriate cut separation routines. The heuristic procedures are called in a similar fashion. We illustrate the use of LS-LIB on an intractable two-level problem, and a hard multi-level problem.

The emerging field of context-oriented programming gives a predominant role to the execution context of applications, and advocates the use of dedicated mechanisms to allow the elegant expression of behavioural adaptations to such context. With suitable reflective facilities, language semantics can be adapted to context by reusing the same context-oriented mechanisms that allow base-level adaptability. This kind of meta-level adaptability, in which the computation model itself becomes adaptable to context, gives rise to context-oriented computational reflection. To explore this idea, we set out to implement a simple software transactional memory system that exploits meta-level adaptability by regarding transactions as contexts, and adapting fundamental system behaviour to such transactional contexts. The implementation is succinct and non-intrusive, giving us an indication of the power lying at the crossroads of context-oriented programming and computational reflection

Haplotyping estimation from aligned single nucleotide polymorphism fragments has attracted increasing attention in recent years because of its importance in the analysis of fine-scale genetic data. Its application fields range from mapping of complex disease genes to inferring population histories, passing through designing drugs, functional genomics, and pharmacogenetics. The literature proposes several criteria for haplotyping populations, each of them characterized by biological motivations. One of the most important haplotyping criteria is parsimony, which consists of finding the minimum number of haplotypes necessary to explain a given set of genotypes. Parsimonious haplotype estimation is an hard problem for which the literature has pro- posed several integer programming (IP) models. Here, we describe a new polynomial-sized IP model based on the concept of class representatives, already used for the coloring problem. We propose valid inequalities to strengthen our model and show, through computational experiments, that our model outperforms the best IP models currently known in literature.

We present a semi-Markov model for recognizing scene text that integrates character and word segmentation with recognition. Using wavelet features, it requires only approximate location of the text baseline and font size; no binarization or prior word segmentation is necessary. Our system is aided by a lexicon, yet it also allows non-lexicon words. To facilitate inference with a large lexicon, we use an approximate Viterbi beam search. Our system performs robustly on low-resolution images of signs containing text in fonts atypical of documents., citation/reference: Copyright c 2008 IEEE. Reprinted from R. Duin, D. Laurendeau, B. Lovell, editors, Proc. Intl. Conf. on Pattern Recognition (ICPR), Tampa, FL, USA, December 2008.

A planar quasi-optical Schottky receiver based on the quasi-integrated horn antenna has been developed and tested over the 230???280GHz bandwidth. The receiver consists of a planar GaAs Schottky diode placed at the feed of a dipole-probe suspended on a thin dielectric membrane in an etched-pyramidal horn cavity. The diode has a 1.2??m anode diameter and a low parasitic capacitance due to the use of an etched surface channel. The antenna-mixer results in a measured DSB conversion loss and noise temperature at 258GHz of 7.2dB??0.5dB and 1310K??70K, respectively, at room temperature. The design is compatible with SIS mixers, and the low cost of fabrication and simplicity makes it ideal for submillimeter-wave imaging arrays requiring a 10???20% bandwidth.

The domain independent design system (DIDS) provides a set of tools for rapidly constructing new configuration design systems from a library of reusable software elements called mechanisms . A DIDS user begins by creating a model of the problem domain and the task to be automated. This includes describing a library of parts from which new artifacts could be configured, optimization and preference criteria, and functionality constraints. DIDS analyzes this input and automatically builds an operational prototype system by selecting and combining mechanisms. DIDS' ability to automate this process is derived from its model of configuration design, which enables reusable mechanisms to be identified and automatically selected based on a problem's characteristics. The use of DIDS is illustrated by showing how DIDS solved an elevator-configuration problem.

Conventional approaches to recovering depth from gray-level imagery have involved obtaining two or more images, applying an???interest??? operator, and solving the correspondence problem. Unfortunately, the computational complexity involved in feature extraction and solving the correspondence problem makes existing techniques unattractive for many real-world robotic applications. By approaching the problem from more of an engineering perspective, we have developed a new depth recovery technique that completely avoids the computationally intensive steps of feature selection and correspondence required by conventional approaches. The Intensity Gradient Analysis technique (IGA) is a depth recovery algorithm that exploits the properties of the MCSO (moving camera, stationary objects) scenario. Depth values are obtained by analyzing temporal intensity gradients arising from the optic flow field induced by known camera motion. In doing so, IGA avoids the feature extraction and correspondence steps of conventional approaches and is therefore very fast. A detailed description of the algorithm is provided along with experimental results from complex laboratory scenes.

Scheduling is one of the most often addressed optimization problems in DSP compilation, behavioral synthesis, and system-level synthesis research. With the rapid pace of changes in modern DSP applications requirements and implementation technologies, however, new types of scheduling challenges arise. This paper is concerned with the problem of scheduling blocks of computations in order to optimize the efficiency of their execution on programmable embedded systems under a realistic timing model of their processors. We describe an effective scheme for scheduling the blocks of any computation on a given system architecture and with a specified algorithm implementing each block. We also present algorithmic techniques for performing optimal block scheduling simultaneously with optimal architecture and algorithm selection. Our techniques address the block scheduling problem for both single- and multiple-processor system platforms and for a variety of optimization objectives including throughput, cost, and power dissipation. We demonstrate the practical effectiveness of our techniques on numerous designs and synthetic examples.

We have created a system for music search and retrieval. A user sings a theme from the desired piece of music. The sung theme (query) is converted into a sequence of pitch-intervals and rhythms. This sequence is compared to musical themes (targets) stored in a database. The top pieces are returned to the user in order of similarity to the sung theme. We describe, in detail, two different approaches to measuring similarity between database themes and the sung query. In the first, queries are compared to database themes using standard string-alignment algorithms. Here, similarity between target and query is determined by edit cost. In the second approach, pieces in the database are represented as hidden Markov models (HMMs). In this approach, the query is treated as an observation sequence and a target is judged similar to the query if its HMM has a high likelihood of generating the query. In this article we report our approach to the construction of a target database of themes, encoding, and transcription of user queries, and the results of preliminary experimentation with a set of sung queries. Our experiments show that while no approach is clearly superior to the other system, string matching has a slight advantage. Moreover, neither approach surpasses human performance.