Technology
System identification and modeling for interacting and non-interacting tank systems using intelligent techniques
Bhuvaneswari, N. S., Praveena, R., Divya, R.
System identification from the experimental data plays a vital role for model based controller design. Derivation of process model from first principles is often difficult due to its complexity. The first stage in the development of any control and monitoring system is the identification and modeling of the system. Each model is developed within the context of a specific control problem. Thus, the need for a general system identification framework is warranted. The proposed framework should be able to adapt and emphasize different properties based on the control objective and the nature of the behavior of the system. Therefore, system identification has been a valuable tool in identifying the model of the system based on the input and output data for the design of the controller. The present work is concerned with the identification of transfer function models using statistical model identification, process reaction curve method, ARX model, genetic algorithm and modeling using neural network and fuzzy logic for interacting and non interacting tank process. The identification technique and modeling used is prone to parameter change & disturbance. The proposed methods are used for identifying the mathematical model and intelligent model of interacting and non interacting process from the real time experimental data.
Toward an Integrated Framework for Automated Development and Optimization of Online Advertising Campaigns
Thomaidou, Stamatina, Vazirgiannis, Michalis, Liakopoulos, Kyriakos
Creating and monitoring competitive and cost-effective pay-per-click advertisement campaigns through the web-search channel is a resource demanding task in terms of expertise and effort. Assisting or even automating the work of an advertising specialist will have an unrivaled commercial value. In this paper we propose a methodology, an architecture, and a fully functional framework for semi- and fully- automated creation, monitoring, and optimization of cost-efficient pay-per-click campaigns with budget constraints. The campaign creation module generates automatically keywords based on the content of the web page to be advertised extended with corresponding ad-texts. These keywords are used to create automatically the campaigns fully equipped with the appropriate values set. The campaigns are uploaded to the auctioneer platform and start running. The optimization module focuses on the learning process from existing campaign statistics and also from applied strategies of previous periods in order to invest optimally in the next period. The objective is to maximize the performance (i.e. clicks, actions) under the current budget constraint. The fully functional prototype is experimentally evaluated on real world Google AdWords campaigns and presents a promising behavior with regards to campaign performance statistics as it outperforms systematically the competing manually maintained campaigns.
Cross-conformal predictors
The method of conformal prediction produces set predictions that are automatically valid in the sense that their unconditional coverage probability is equal to or exceeds a preset confidence level ([14], Chapter 2). A more computationally efficient method of this kind is that of inductive conformal prediction ([12], [14], Section 4.1, [1]). However, inductive conformal predictors are typically less predictively efficient, in the sense of producing larger prediction sets as compared with conformal predictors. Motivated by the method of cross-validation [11, 13], this note explores a hybrid method, which we call cross-conformal prediction. We are mainly interested in the problems of classification and regression, in which we are given a training set consisting of examples, each example consisting of an object and a label, and asked to predict the label of a new test object; in the problem of classification labels are elements of a given finite set, and in the problem of regression labels are real numbers. If we are asked to predict labels for more than one test objects, the same prediction procedure can be applied to each test object separately. In this introductory section and in our empirical studies we consider the problem of binary classification, in which labels can take only two values, which we will encode as 0 and 1. We always assume that the examples (both the training examples and the test examples, consisting of given objects and unknown labels) are generated independently from the same probability measure; this assumption will be called the assumption of randomness.
Fast and Accurate Algorithms for Re-Weighted L1-Norm Minimization
Asif, M. Salman, Romberg, Justin
To recover a sparse signal from an underdetermined system, we often solve a constrained L1-norm minimization problem. In many cases, the signal sparsity and the recovery performance can be further improved by replacing the L1 norm with a "weighted" L1 norm. Without any prior information about nonzero elements of the signal, the procedure for selecting weights is iterative in nature. Common approaches update the weights at every iteration using the solution of a weighted L1 problem from the previous iteration. In this paper, we present two homotopy-based algorithms that efficiently solve reweighted L1 problems. First, we present an algorithm that quickly updates the solution of a weighted L1 problem as the weights change. Since the solution changes only slightly with small changes in the weights, we develop a homotopy algorithm that replaces the old weights with the new ones in a small number of computationally inexpensive steps. Second, we propose an algorithm that solves a weighted L1 problem by adaptively selecting the weights while estimating the signal. This algorithm integrates the reweighting into every step along the homotopy path by changing the weights according to the changes in the solution and its support, allowing us to achieve a high quality signal reconstruction by solving a single homotopy problem. We compare the performance of both algorithms, in terms of reconstruction accuracy and computational complexity, against state-of-the-art solvers and show that our methods have smaller computational cost. In addition, we will show that the adaptive selection of the weights inside the homotopy often yields reconstructions of higher quality.
Evolutionary Inference for Function-valued Traits: Gaussian Process Regression on Phylogenies
Jones, Nick S., Moriarty, John
In this paper we consider statistical inference for function-valued data which are correlated due to phylogenetic relationships. A schematic example is given in Figure 1A: in this case, given functional data observed at the tips of a phylogeny, the task is to perform inference on the (unobserved) functional data at the root of the phylogeny. Alternatively, if the phylogeny is uncertain we may wish to perform phylogenetic inference, or our interest may be inferring the dynamics of the evolutionary process which produced the data. The term'function-valued' is meant in the sense of [1], where a datum is a continuous functionf (x) of a variablex, such as time or temperature: an examples are therefore curves for ambient temperature versus growth rate for caterpillars, a heart rhythm time series [2], or a spectrogram of audio data. Our approach is to combine the theory of Gaussian processes with assumptions from phylogenetics, to obtain a flexible nonparametric model for such data.
Ancestral Inference from Functional Data: Statistical Methods and Numerical Examples
Hadjipantelis, Pantelis Z., Jones, Nick S., Moriarty, John, Springate, David, Knight, Christopher G.
Many biological characteristics of evolutionary interest are not scalar variables but continuous functions. Here we use phylogenetic Gaussian process regression to model the evolution of simulated function-valued traits. Given function-valued data only from the tips of an evolutionary tree and utilising independent principal component analysis (IPCA) as a method for dimension reduction, we construct distributional estimates of ancestral function-valued traits, and estimate parameters describing their evolutionary dynamics.
Multidimensional Membership Mixture Models
Jiang, Yun, Lim, Marcus, Saxena, Ashutosh
We present the multidimensional membership mixture (M3) models where every dimension of the membership represents an independent mixture model and each data point is generated from the selected mixture components jointly. This is helpful when the data has a certain shared structure. For example, three unique means and three unique variances can effectively form a Gaussian mixture model with nine components, while requiring only six parameters to fully describe it. In this paper, we present three instantiations of M3 models (together with the learning and inference algorithms): infinite, finite, and hybrid, depending on whether the number of mixtures is fixed or not. They are built upon Dirichlet process mixture models, latent Dirichlet allocation, and a combination respectively. We then consider two applications: topic modeling and learning 3D object arrangements. Our experiments show that our M3 models achieve better performance using fewer topics than many classic topic models. We also observe that topics from the different dimensions of M3 models are meaningful and orthogonal to each other.
A Probabilistic Attack on NP-complete Problems
Using the probability theory-based approach, this paper reveals the equivalence of an arbitrary NP-complete problem to a problem of checking whether a level set of a specifically constructed harmonic cost function (with all diagonal entries of its Hessian matrix equal to zero) intersects with a unit hypercube in many-dimensional Euclidean space. This connection suggests the possibility that methods of continuous mathematics can provide crucial insights into the most intriguing open questions in modern complexity theory.
Fast Planar Correlation Clustering for Image Segmentation
Yarkony, Julian, Ihler, Alexander T., Fowlkes, Charless C.
We describe a new optimization scheme for finding high-quality correlation clusterings in planar graphs that uses weighted perfect matching as a subroutine. Our method provides lower-bounds on the energy of the optimal correlation clustering that are typically fast to compute and tight in practice. We demonstrate our algorithm on the problem of image segmentation where this approach outperforms existing global optimization techniques in minimizing the objective and is competitive with the state of the art in producing high-quality segmentations.
Oracle inequalities for computationally adaptive model selection
Agarwal, Alekh, Bartlett, Peter L., Duchi, John C.
We analyze general model selection procedures using penalized empirical loss minimization under computational constraints. While classical model selection approaches do not consider computational aspects of performing model selection, we argue that any practical model selection procedure must not only trade off estimation and approximation error, but also the computational effort required to compute empirical minimizers for different function classes. We provide a framework for analyzing such problems, and we give algorithms for model selection under a computational budget. These algorithms satisfy oracle inequalities that show that the risk of the selected model is not much worse than if we had devoted all of our omputational budget to the optimal function class.