A simulation-based heuristic algorithm for disposition of direction finders

A direction finder is a military weapon that is used to find locations of targets that emit radio frequencies. Multiple direction finders are used in a direction finder system for finding locations of targets in an area of interest. We present a two-stage heuristic algorithm for disposing direction finders in a direction finder system for the objective of maximizing the accuracy of estimation of the location of a target that is assumed to be located in the area of interest. In the suggested heuristic algorithm, a simulation-based method is used for estimating the probability of coverage, the probability that a target is in a given region (of a given size) surrounding the estimated location of the target, and another simulation-based method and a local search method are used to determine locations of direction finders that result in the maximum probability of coverage. Performance of the suggested algorithm is evaluated through computational experiments and results show that the algorithm gives a good disposition plan in a reasonable amount of computation time.     

Fermion confinement induced by geometry

We consider a five-dimensional model in which fermions are confined in a hypersurface due to an interaction with a purely geometric field. Inspired by the Rubakov-Shaposhnikov field-theoretical model, in which massless fermions can be localized in a domain wall through the interaction of a scalar field, we show that particle confinement may also take place if we endow the five-dimensional bulk with a Weyl integrable geometric structure, or if we assume the existence of a torsion field acting in the bulk. In this picture, the kind of interaction considered in the Rubakov-Shaposhnikov model is replaced by an interaction of fermions with a geometric field, namely a Weyl scalar field or a torsion field. We show that in both cases the confinement is independent of the energy and mass of the fermionic particle. We generalize these results to the case in which the bulk is an arbitrary n-dimensional curved space.     

The conversion of a dynamic B-spline curve into piecewise polynomials in power form

The evaluation of points and the computations of inflection points or cusps on a curve are often necessary in CAGD applications. When a curve is represented in a B-spline form, such computations can be made easier once it is transformed into a set of piecewise polynomial curves in power form. The usual practice of the transformation of a B-spline curve into a set of piecewise polynomial curves in power form is done either by a knot refinement followed by basis conversions, or by applying a Taylor expansion on each knot span of a B-spline curve.Presented in this paper is a new algorithm to convert a B-spline curve into a set of piecewise polynomial curves in power form. Experiment shows that the proposed algorithm significantly outperforms the conventional approach when one or more control points of a B-spline curve are continuously moving.     

Motion of a rigid cylinder between parallel plates in stokes flow : Part 1: Motion in a quiescent fluid and sedimentation

A general numerical scheme for solution of two-dimensional Stokes equations in a multiconnected domain of arbitrary shape [1, 2] is applied to the motion of a rigid circular cylinder between plane parallel boundaries. Numerically generated boundary-conforming coordinates are used to transform the flow domain into a domain with rectilinear boundaries. The transformed Stokes equations in vorticity-stream function form are then solved on a uniform grid using an iterative algorithm. In Part I coefficients of the resistance matrix representing the forces and torque on the cylinder due to its translational motion parallel or perpendicular to the boundaries or due to rotation about its axis are calculated. The solutions are obtained for a wide range of particle radii and positions across the channel. It is found that the force on a particle translating parallel to the boundaries without rotation exhibits a minimum at a position between the channel centerline and the wall and a local maximum on the centerline.

The resistance matrix is utilized to calculate translational and angular velocities of a free particle settling under gravity in a vertical channel. It is found that the translational velocity has a maximum at some lateral position and a minimum on the centerline; the particle angular velocity is opposite in sign to that of a particle rolling along the nearer channel wall except when the gap between the particle and the wall is very small. These results are compared with existing analytical solutions for a small cylindrical particle situated on the channel centerline, and with solutions of related 3-D problems for a spherical particle in a circular tube and in a place channel. It is shown that the behavior of cylindrical and spherical particles in a channel in many cases is qualitatively different. This is attributed to different flow patterns in these two cases. The motion of a spherical particle in a circular tube has qualitative and quantitative features similar to those for a cylindrical particle in a plane channel.     

Optical merger of direct vision with virtual images for scaled teleoperation

Scaled teleoperation is increasingly prevalent in medicine, as well as in other applications of robotics. Visual feedback in such systems is essential and should make maximal use of natural hand-eye coordination. This paper describes a new method of visual feedback for scaled teleoperation in which the operator manipulates the handle of a remote tool in the presence of a registered virtual image of the target in real time. The method adapts a concept already used successfully in a new medical device called the sonic flashlight, which permits direct in situ visualization of ultrasound during invasive procedures. The sonic flashlight uses a flat-panel monitor and a half-silvered mirror to merge the visual outer surface of a patient with a simultaneous ultrasound scan of the patient's interior. Adapting the concept to scaled teleoperation involves removing the imaging device and the target to a remote location and adding a master-slave control device. This permits the operator to see his hands, along with what appears to be the tool, and the target, merged in a workspace that preserves natural hand-eye coordination. Three functioning prototypes are described, one based on ultrasound and two on light microscopy. The limitations and potential of the new approach are discussed.     

Dynamic setup scheduling and flow control in manufacturing systems

We propose a method for flow control of parts in a manufacturing system with machines that require setups. The setup scheduling problem is investigated in the context of a multilevel hierarchy of discrete events with distinct frequencies. The higher level of the hierarchy calculates a target trajectory in the surplus/backlog space of the part types which must be tracked at the level of setups. We consider a feedback setup scheduling policy which usescorridors in the surplus/backlog space of the part types to determine the timing of the set-up changes in order to guide the trajectory in the desired direction. An interesting case in which the trajectory leads to a target point (e.g., a hedging point) is investigated in detail. It is shown that in this case the surplus/backlog trajectory at the setup level can lead to a limit cycle. Conditions for linear corridors which result in a stable limit cycle are determined.     

Completing codes in a sofic shift

We define a code in a sofic shift as a set of blocks of symbols of the shift such that any block of the shift has at most one decomposition into code words. It is maximal if it is not strictly included in another one. Such a code is complete in the sofic shift if any block of the shift occurs within some concatenation of code words. We prove that a maximal code in an irreducible sofic shift is complete in this shift. We give an explicit construction of a regular completion of a regular code in a sofic shift. This extends the well known result of Ehrenfeucht and Rozenberg to the case of codes in sofic systems. We also give a combinatorial proof of a result concerning the polynomial of a code in a sofic shift.     

判别线面相交及面面相交可见性的假想墙法

针对判别直线与平面相交及平面与平面相交的可见性提出了一种假想墙的方法。 在直线与平面相交问题中探讨了 3 种典型的情况：一般位置直线与特殊位置平面相交、一般位 置直线与一般位置平面相交、特殊位置直线与一般位置平面相交;在平面与平面相交的问题中 探讨了 3 种典型的情况：特殊位置平面与特殊位置平面相交、一般位置平面与特殊位置平面相 交、一般位置平面与一般位置平面相交。通过假想墙方法,可快速准确地判断直线与平面相交 及平面与平面相交的可见性,为机械制图课程相关内容的学习及教学提供一些参考。     

A constructive algorithm to solve "convex recursive deletion" (CoRD) classification problems via two-layer perceptron networks.

A sufficient condition that a region be classifiable by a two-layer feedforward neural net (a two-layer perceptron) using threshold activation functions is that either it be a convex polytope or that intersected with the complement of a convex polytope in its interior, or that intersected with the complement of a convex polytope in its interior or... recursively. These have been called convex recursive deletion (CoRD) regions. We give a simple algorithm for finding the weights and thresholds in both layers for a feedforward net that implements such a region. The results of this work help in understanding the relationship between the decision region of a perceptron and its corresponding geometry in input space. Our construction extends in a simple way to the case that the decision region is the disjoint union of CoRD regions (requiring three layers). Therefore this work also helps in understanding how many neurons are needed in the second layer of a general three-layer network. In the event that the decision region of a network is known and is the union of CoRD regions, our results enable the calculation of the weights and thresholds of the implementing network directly and rapidly without the need for thousands of backpropagation iterations.     

Visual displays: the highlighting paradox

Office computer users view well over a billion displays in a given year. The savings of only a fraction of a second in the time it takes users to process each display can potentially lead to enormous time and cost savings. In recent research investigators have shown that on average subjects are quicker to find a target option in a highlighted display than in a display without highlighting. Paradoxically, in related research other investigators have shown that subjects are slower to find a target in a highlighted display than in a display without highlighting. In an attempt to resolve this paradox, an additional set of experiments was performed. Results from these experiments suggest that in order to determine whether highlighting will be of benefit, one must know the type of highlighting, the level of highlighting validity, and the probability that subjects attend first to the highlighted options.     

An efficient distributed algorithm for detection of knots and cycles in a distributed graph

Knot detection in a distributed graph is an important problem and finds applications in deadlock detection in several areas such as store-and-forward networks, distributed simulation, and distributed database systems. This paper presents an efficient distributed algorithm to detect if a node is part of a knot in a distributed graph. The algorithm requires 2e messages and a delay of 2(d+1) message hops to detect if a node in a distributed graph is in a knot (here, e is the number of edges in the reachable part of the distributed graph and d is its diameter). A significant advantage of this algorithm is that it not only detects if a node is involved in a knot, but also finds exactly which nodes are involved in the knot. Moreover, if the node is not involved in a knot, but is only involved in a cycle, then it finds the nodes that are in a cycle with that node. We illustrate the working of the algorithm with examples. The paper ends with a discussion on how the information about the nodes involved in the knot can be used for deadlock resolution and also on the performance of the algorithm.     

Facial Recognition System for Suspect Identification Using a Surveillance Camera

Nowadays, finding and Tracking a person in the world of technology is becoming a necessary task for various security purposes. Since the advent of technology, the development in the field of Facial Recognition plays an important role and has been exponentially increasing in today’s world. In this, a model is proposed for facial recognition to identify and alert the system when a person in search has been found at a specific location under the surveillance of a CCTV camera. The CCTV cameras are connected to a centralized server to which the live streaming feed is uploaded by cameras at each location. The server contains a database of all persons to be found. Based on the video feed from each camera, if a particular person in search is found in a certain feed, then the location of that person will be tracked and also a signal is passed to the system responsible. This model is based on image processing concepts to match live images with the existing trained images of the person in search. Since this model recognizes a person based on the first and foremost primary unique feature of a human, that is, only the person’s face image is required and will be found to be stored in the database. Hence the task of finding a person reduces to the task of detecting human faces in the video feed and matching with the existing images from the database.     

Query optimization in multidatabase systems considering schemaconflicts

In a multidatabase system, the participating databases are autonomous. The schemas of these databases may be different in various ways, while the same information is represented. A global query issued against the global database needs to be translated to a proper form before it can be executed in a local database. Since data requested by a query (or a part of a query) is sometimes available in multiple sites, the site (database) that processes the query with the least cost is the desired query processing site. The authors study the effect of differences in schemas on the cost of query processing in a multidatabase environment. They first classify schema conflicts to different types. For each type of conflict, they show how much more or less complex a translated query can become in comparison with the originally user-issued global query. Based on this observation, they propose an analytical method that considers the conflicts between local databases and finds the database(s) that renders the least execution cost in processing a global query. This research introduces a new level of query optimization (termed the schema-level optimization) in multidatabase environments. The results provide a new dimension of enhancement for the capability of a query optimizer in multidatabase systems     

Graph-based shape indexing

Graphs have become growingly important in representing shapes in computer vision. Given a query graph, it is essential to retrieve similar database graphs efficiently from a large database. In this paper, we present a graph-based indexing technique which overcomes significant drawbacks of the previous work (Demirci et al. in Comput Vis Image Underst 110(3):312–325, 2008) using a recently developed theorem from the domain of matrix analysis. Our technique starts by representing the topological structure of a graph in a vector space. As done in the previous work, the topological structure of a graph is constructed using its Laplacian spectra. However, unlike the previous approach, which represents all sugraphs of a database graph in the vector space to account for local similarity, a database graph in the proposed framework is represented as a single vector. By performing a range search around the query, the proposed indexing technique returns a set with both partial and global similarity. Empirical evaluation of the algorithm on an extensive set of retrieval trials including a comparison with the previous approach in both 2D and 3D demonstrates the effectiveness, efficiency, and robustness of the overall approach.     

A preliminary study on learning effect in a contact positioning task in a virtual environment

How the human central nervous system adjusts sensorimotor coordination to haptic stimuli is a major topic in several fields including robotics. There are studies focusing on contact positioning tasks such as catching a ball or a volley in tennis, where position control of a human hand is required only at the moment of contact for successful completion of the tasks. A previous study dealt with a task of catching a ball in a virtual environment, and reported an interesting observation of the learning process in the relationship between operational performance and energy consumption of an operator; however, the operational condition given to the operators in the previous study seemed to be relatively simple. The interest in this paper is similar to that of the previous study; however, this paper considers application of a slightly more complex operational condition to a task of catching a ball. For corresponding to increase of difficulty in operation in the task, two movements of a paddle for catching a ball are given to operators, and difference between the movements is observed. Although the final goal of the study in this paper is similar to that in the previous study, this paper considers how learning effect can be observed in operational performance by comparing the performance of novice operators with that of experienced operators. The comparison shows differences in the performances between the operators from three analytic aspects. This paper also considers how many operations are required for novice operators to exhibit the learning effect in operational performance.     

A method for taxonomy development and its application in information systems

A fundamental problem in many disciplines is the classification of objects in a domain of interest into a taxonomy. Developing a taxonomy, however, is a complex process that has not been adequately addressed in the information systems (IS) literature. The purpose of this paper is to present a method for taxonomy development that can be used in IS. First, this paper demonstrates through a comprehensive literature survey that taxonomy development in IS has largely been ad hoc. Then the paper defines the problem of taxonomy development. Next, the paper presents a method for taxonomy development that is based on taxonomy development literature in other disciplines and shows that the method has certain desirable qualities. Finally, the paper demonstrates the efficacy of the method by developing a taxonomy in a domain in IS.     

Visiting Byzantine Agreement underlying Ad Hoc environment

The Mobile Ad Hoc Network (MANET) has become more popular because the MANET is a self-organizing, self-configuring, and an instantly deployable multi-hop wireless network that responds to application needs without any fixed infrastructure. Moreover, the MANET is fault-tolerant and reliable. A mechanism is needed in the MANET that allows a set of nodes to agree on a common value. The distributed Byzantine Agreement (BA) problem is one of the most important issues in designing a fault-tolerant system. In many cases, reaching a common agreement among fault-free nodes in coping with the influence from faulty components is crucial in a fault-tolerant system. When a common agreement is achieved, all fault-free nodes in the system can produce stable results without any influence from the faulty components. In this study, the BA problem is visited in a MANET, in which the components are subject to a malicious fault. The proposed protocol can tolerate the maximum number of allowable faulty nodes using a minimum number of message exchange rounds. Each fault-free node can reach a common agreement value for the BA problem in a MANET. The text was submitted by the authors in English.     

Multivariate autoregressive modeling of autonomic cardiovascular control in neonatal lamb

The neonatal cardiovascular control system is a complicated interactive system which is under vigorous development at birth. From the measurement point of view the cardiovascular control is a closed-loop system. However, it can be examined on a beat-by-beat basis by analyzing circulatory-controlled variables with advanced signal analysis techniques. This paper proposes to use a multivariate autoregressive modeling technique in the analysis of several simultaneous physiological signals in order to examine interactions and inherent properties in the system. With the proposed multivariate autoregressive modeling technique, a signal is modeled as a linear combination of its own past and the past values of the other simultaneous signals plus a predictive error term of the model. The interactions in the system after the model identification are analyzed in frequency domain utilizing power spectrum estimates of the signals and signal contributions. The applicability of the proposed method was examined by a three-variable model between heart rate, blood pressure and respiration in the study of autonomic cardiovascular control in a chronic neonatal lamb model, in which the cardiovascular status was changed by using a beta-adrenergic autonomic nervous blockade. The study showed that the multivariate autoregressive modeling technique is a feasible technique in studying complicated interactions within the cardiovascular control system.     

基于OpenGL的网格数据三维地形鼠标取值方法

在OpenGL的三维场景模拟中,通过鼠标取点得到该点的三维坐标一直是一个难题,而在三维地形模拟中则进一步要求通过鼠标取点得到该点在地形数据中的实际值,即用鼠标取值,因此OpenGL三维地形的鼠标取值一直是这类应用程序中的难点。文章在解决实际问题的基础上实现了一种解决基于OpenGL的网格数据的三维地形的鼠标取值方法。