An Asymptotically Exact Approach to Robust Semidefinite Programming Problems with Function Variables

This technical note provides an approximate approach to a semidefinite programming problem with a parameter-dependent constraint and a function variable. This problem covers a variety of control problems including a robust stability/performance analysis with a parameter-dependent Lyapunov function. In the proposed approach, the original problem is approximated by a standard semidefinite programming problem through two steps: first, the function variable is approximated by a finite-dimensional variable; second, the parameter-dependent constraint is approximated by a finite number of parameter-independent constraints. Both steps produce approximation error. On the sum of these approximation errors, this technical note provides an upper bound. This bound enables quantitative analysis of the approach and gives an efficient way to reduction of the approximation error. Moreover, this technical note discusses how to verify that an optimal solution of the approximate problem is actually optimal also for the original problem.      

A Triangulation Approach to Asymptotically Exact Conditions for Fuzzy Summations

Many Takagi-Sugeno (T-S) fuzzy control-synthesis problems in the literature are expressed as the problem of finding decision variables in a double convex sum (fuzzy summation) of positive definite matrices. Matricespsila coefficients in the summation take values in the standard simplex. This paper presents a triangulation approach to the problem of generating simplicial partitions of the standard simplex in order to set up a family of sufficient conditions and, in parallel, another family of necessary ones for fuzzy summations. The conditions proposed in this paper are asymptotically exact as the size of the involved simplices decreases; its conservativeness vanishes for a sufficiently fine partition (sufficiently dense mesh of vertex points). The set of conditions is in the form of linear matrix inequalities (LMIs), for which efficient software is available.     

An Adversarial Neuro-Tensorial Approach for Learning Disentangled Representations

International Journal of Computer Vision - Several factors contribute to the appearance of an object in a visual scene, including pose, illumination, and deformation, among others. Each factor...     

一种基于多分量信息融合的人脸检测方法

人脸检测是全自动人脸识别系统和许多监视系统的基础,在许多领域有着广泛的应用。文章提出了一种基于多分量信息融合的人脸检测方法。首先进行彩色空间的变换,检测出图像中的肤色区域;建立眼睛颜色模型,并根据眼睛﹑嘴在不同分量上的分布特征,将它们提取出来;最后融合眼睛﹑嘴候选区域的信息,利用特征不变的方法进行人脸的确定。实验结果表明,该方法能够快速有效地检测出人脸,并能够确定眼﹑嘴的位置。     

Swing-Up Control of the Pendubot: An Impulse–Momentum Approach

The standard control problem of the pendubot refers to the task of stabilizing its equilibrium configuration with the highest potential energy. Linearization of the dynamics of the pendubot about this equilibrium results in a completely controllable system and allows a linear controller to be designed for local asymptotic stability. For the underactuated pendubot, the important task is, therefore, to design a controller that will swing up both links and bring the configuration variables of the system within the region of attraction of the desired equilibrium. This paper provides a new method for swing-up control based on a series of rest-to-rest maneuvers of the first link about its vertically upright configuration. The rest-to-rest maneuvers are designed such that each maneuver results in a net gain in energy of the second link. This results in swing-up of the second link and the pendubot configuration reaching the region of attraction of the desired equilibrium. A four-step algorithm is provided for swing-up control followed by stabilization. Simulation results are presented to demonstrate the efficacy of the approach.      

From Chronological Calculus to Exponential Representations of Continuous and Discrete-Time Dynamics: A Lie-Algebraic Approach

In this paper, formal exponential representations of the solutions to nonautonomous nonlinear differential equations are derived. It is shown that the chronological exponential admits an ordinary exponential representation, the exponent being given by an explicitly computable Lie series expansion. The results are then used to describe controlled dynamics, dynamics under sampling and forced discrete-time dynamics. The study emphasizes the role of Lie algebra techniques in nonlinear control theory and specifies structural similarities between nonautonomous differential equations, dynamics under sampling and forced discrete-time dynamics up to hybrid ones.     

Exact Histogram Specification for Digital Images Using a Variational Approach

We consider the problem of exact histogram specification for digital (quantized) images. The goal is to transform the input digital image into an output (also digital) image that follows a prescribed histogram. Classical histogram modification methods are designed for real-valued images where all pixels have different values, so exact histogram specification is straightforward. Digital images typically have numerous pixels which share the same value. If one imposes the prescribed histogram to a digital image, usually there are numerous ways of assigning the prescribed values to the quantized values of the image. Therefore, exact histogram specification for digital images is an ill-posed problem. In order to guarantee that any prescribed histogram will be satisfied exactly, all pixels of the input digital image must be rearranged in a strictly ordered way. Further, the obtained strict ordering must faithfully account for the specific features of the input digital image. Such a task can be realized if we are able to extract additional representative information (called auxiliary attributes) from the input digital image. This is a real challenge in exact histogram specification for digital images. We propose a new method that efficiently provides a strict and faithful ordering for all pixel values. It is based on a well designed variational approach. Noticing that the input digital image contains quantization noise, we minimize a specialized objective function whose solution is a real-valued image with slightly reduced quantization noise, which remains very close to the input digital image. We show that all the pixels of this real-valued image can be ordered in a strict way with a very high probability. Then transforming the latter image into another digital image satisfying a specified histogram is an easy task. Numerical results show that our method outperforms by far the existing competing methods.     

Technology Selection: An Educational Approach

Creating and enhancing a software engineering work force requires several different types of continuing education for software professionals, including: task-oriented education, enhancement-oriented education and selection-oriented education. In this paper, we focus on the important, but often neglected, category of selection-oriented education. We begin with a discussion of technology selection, indicating what it involves, how it contributes to improving the state of practice, and why it is key to technology improvement in general. This is followed by a discussion of some criteria for selection-oriented education programs. We then describe the selection-oriented education activities at the Rocky Mountain Institute of Software Engineering and relate some problems encountered in establishing these activities.     

Conscious Representations: An Intractable Problem for the Computational Theory of Mind

Advocates of the computational theory of mind claim that the mind is a computer whose operations can be implemented by various computational systems. According to these philosophers, the mind is multiply realisable because—as they claim—thinking involves the manipulation of syntactically structured mental representations. Since syntactically structured representations can be made of different kinds of material while performing the same calculation, mental processes can also be implemented by different kinds of material. From this perspective, consciousness plays a minor role in mental activity. However, contemporary neuroscience provides experimental evidence suggesting that mental representations necessarily involve consciousness. Consciousness does not only enable individuals to become aware of their own thoughts, it also constantly changes the causal properties of these thoughts. In light of these empirical studies, mental representations appear to be intrinsically dependent on consciousness. This discovery represents an obstacle to any attempt to construct an artificial mind.     

An Effective and Efficient Exact Match Retrieval Scheme for Symbolic Image Database Systems Based on Spatial Reasoning: A Logarithmic Search Time Approach

In this paper, a novel method of representing symbolic images in a symbolic image database (SID) invariant to image transformations that is useful for exact match retrieval is presented. The relative spatial relationships existing among the components present in an image are perceived with respect to the direction of reference [15] and preserved by a set of triples. A distinct and unique key is computed for each distinct triple. The mean and standard deviation of the set of keys computed for a symbolic image are stored along with the total number of keys as the representatives of the corresponding image. The proposed exact match retrieval scheme is based on a modified binary search technique and, thus, requires O(log n) search time in the worst case, where n is the total number of symbolic images in the SID. An extensive experimentation on a large database of 22,630 symbolic images is conducted to corroborate the superiority of the model. The effectiveness of the proposed representation scheme is tested with standard testbed images.     

An Asymptotically Efficient Simulation-Based Algorithm for Finite Horizon Stochastic Dynamic Programming

We present a simulation-based algorithm called "Simulated Annealing Multiplicative Weights" (SAMW) for solving large finite-horizon stochastic dynamic programming problems. At each iteration of the algorithm, a probability distribution over candidate policies is updated by a simple multiplicative weight rule, and with proper annealing of a control parameter, the generated sequence of distributions converges to a distribution concentrated only on the best policies. The algorithm is "asymptotically efficient," in the sense that for the goal of estimating the value of an optimal policy, a provably convergent finite-time upper bound for the sample mean is obtained     

Flowstrates: An Approach for Visual Exploration of Temporal Origin‐Destination Data

Many origin‐destination datasets have become available in the recent years, e.g. flows of people, animals, money, material, or network traffic between pairs of locations, but appropriate techniques for their exploration still have to be developed. Especially, supporting the analysis of datasets with a temporal dimension remains a significant challenge. Many techniques for the exploration of spatio‐temporal data have been developed, but they prove to be only of limited use when applied to temporal origin‐destination datasets. We present Flowstrates , a new interactive visualization approach in which the origins and the destinations of the flows are displayed in two separate maps, and the changes over time of the flow magnitudes are represented in a separate heatmap view in the middle. This allows the users to perform spatial visual queries, focusing on different regions of interest for the origins and destinations, and to analyze the changes over time provided with the means of flow ordering, filtering and aggregation in the heatmap. In this paper, we discuss the challenges associated with the visualization of temporal origin‐destination data, introduce our solution, and present several usage scenarios showing how the tool we have developed supports them.     

Stakeholder Risk Assessment: An Outcome-Based Approach

Managing software projects can often degrade into fighting fires lit by the embers of unrecognized and unmanaged risks. Stakeholders are a recognized source of significant software project risk, but few researchers have focused on providing a practical method for identifying specific project stakeholders. Furthermore, no methods provide guidance in identifying and managing project risks arising from those stakeholders. We developed the outcome-based stakeholder risk assessment model to provide this practical guidance. OBSRAM offers the project team a step-by-step approach to identifying stakeholders during requirements engineering, identifying stakeholder influences on the project, identifying the project's impact on stakeholders, and assessing the risks that their potential negative responses pose. We illustrate OBSRAM using a case study of a simulated airline-crew-scheduling system project that aims to reduce aircraft ground turnaround time to 30 minutes or less     

Tracing DDoS Floods: An Automated Approach

We propose a Controller-Agent model that would greatly minimize distributed denial-of-service (DDoS) attacks on the Internet. We introduce a new packet marking technique and agent design that enables us to identify the approximate source of attack (nearest router) with a single packet even in the case of attacks with spoofed source addresses. Our model is invoked only during attack times, and is able to process the victims traffic separately without disturbing other traffic, it is also able to establish different attack signatures for different attacking sources and can prevent the attack traffic at the nearest router to the attacking system. It is simple in its implementation, it has fast response for any changes in attack traffic pattern, and can be incrementally deployed. Hence we believe that the model proposed in this paper seems to be a promising approach to prevent distributed denial-of-service attacks.     

An evolutionist approach to information bipolarity: Representations and affects in human cognition

This paper investigates the psychological plausibility of the bipolarity concept, i.e., that positive and negative kinds of information are treated differently. Sections 2 and 3 review relevant investigations of the representational and affective systems in the experimental psychology literature. Section 4 provides new data supporting the idea that even when considering how affective changes occur, a certain level of independence exists between the positive and negative sides of affect. Together the studies reported here strongly support the psychological plausibility of bipolarity: Positive and negative kinds of information are not processed in the same way whichever domain is considered, preferences (affect) or beliefs (mental categories). © 2008 Wiley Periodicals Inc.