Search

In control system design, it is important to determine the controller type and controller parameters appropriately. PID controllers are mostly preferred in many applications. At the same time, it is known that PID controllers are insufficient to control higher order oscillatory systems with time delay. In such systems, PIDA controller is preferred instead of traditional PID controller. This paper presents a hybrid algorithm based optimization method for the control of higher order oscillatory systems with time delay. A hybrid algorithm combining the advantages of firefly and genetic algorithm is used to determine PIDA controller parameters. In the proposed method, a multi-criteria objective function is suggested by taking the settling and rising time, percent overshoot and steady state error criteria from the time response parameters. Two simulation studies are conducted to evaluate the performance of the proposed method, and the results are compared with some studies from the literature. In addition, the parameter uncertainties of the systems are analyzed and the robustness performance evaluations of the designed controllers are made. It is seen from the results obtained that the proposed method improves the transient and steady state response of higher order oscillatory systems with time delay and offers a fast and effective tuning method. [ABSTRACT FROM AUTHOR]

Recent studies show that the performance of Evolutionary Algorithms often depends on choosing appropriate parameter configurations. Thus, researchers have generally tuned these parameters either looking at the similar research areas in the literature or manually, e.g. Grid Search. However, searching the parameter manually is laborious and timeconsuming; therefore, meta-optimization techniques have become commonly used methods to adjust parameters of an algorithm. These techniques can be classified in two widespread manners: off-line, tuning parameters of an algorithm before the algorithm initiates, and on-line, tuning the parameters while it is working. In this paper, Bipolar Matching Tendency (BMT) algorithm has been chosen as the selection method of a Genetic Algorithm (GA). The new obtained algorithm is named GA-BMT and has been used for the first time as an online metaoptimizer. In addition, the paper utilizes two search algorithms (Grid Search, Coarse to Fine Search) with three meta-optimization methods (Standard GA, Particle Swarm Optimization, GA-BMT) to investigate the best parameter settings of the Standard GA for 17 test functions, and offers a comparative work by comparing their results. Furthermore, non-parametric statistical tests, Friedman and Wilcoxon Signed Rank, were performed to demonstrate the significance of the results. Based on the all results that achieved, GA-BMT presents a reasonable achievement. [ABSTRACT FROM AUTHOR]

This paper studies how a group of delivery workers in Barcelona were able to organize a successful traditional and a social media strategy in order to claim for their rights as waged workers. They created a union, RidersxDerechos, and they also decided to create a worker's cooperative, Mensakas, with their own application and algorithm. We will study how they were able to re-appropriate technology and to use digital communities to spread alternative discourses. We have used different methodologies: traditional content analysis in Media, debate analysis in Social Media, qualitative ethnography. We noticed that RidersxDerechos access to media was very successful (300 piece of news analyzed) thanks to strikes and court trials, facilitating a change of perspective in the treatment of platform economy in Media. Media were following up the digital entrepreneurship rhetoric until then. Along with the traditional media strategy they developed a diversified communicative pathway in social media (Twitter, Instagram, Facebook, and Goteo) that helped them to establish alliances with riders from other cities and countries. We focused on more than 25.000 tweets. Finally, they proposed a new way to use technology by creating their own app and algorithms for their working cooperative, Mensakas. Crowdfunding was also used to fund it and to spread an alternative working storytelling from Silicon Valley's. [ABSTRACT FROM AUTHOR]

High-rate low-density parity-check (LDPC) codes are the focus of intense research in magnetic recording because, when decoded by the iterative sum-product algorithm, they show decoding performance close to the Shannon capacity. However, cycles, especially short cycles, are harmful to LDPC codes. The paper describes the partition-and-shift LDPC (PS-LDPC) codes, a new class of regular, structured LDPC codes that can be designed with large girth and arbitrary large minimum distance. Large girth leads to more efficient iterative decoding and codes with better error-floor properties than random LDPC codes. PS-LDPC codes can be designed for any desired column weight and with flexible code rates. The paper details the girth and distance properties of the codes and their systematic construction and presents analytical and simulation performance results that show that, in the high signal-to-noise ratio region, PS-LDPC codes out- perform random codes, alleviating the error floor phenomenon. [ABSTRACT FROM AUTHOR]

Many classification algorithms and econometric models require that training examples contain only discrete values. In order to use these algorithms when some variables have continuous values, the numeric variables must be converted into discrete ones. This paper describes a new way of discretizing numeric values using multiple structural changes. [ABSTRACT FROM AUTHOR]

Pulmonary arterial hypertension (PAH) is a clinical syndrome that is often diagnosed late and is associated with a progressive clinical deterioration and death. However, over the past ten years there has been a dramatic increase in the number of effective therapies. Identification of dysfunctional pathways in the pulmonary circulation provided novel therapeutic targets with the goal of reducing pulmonary vascular resistance and death from right ventricular failure. Treatment strategies are determined according to current guidelines. Pulmonary artery vasoreactivity, functional class and response to treatment are important concepts for initiation of medical therapy. With the availability of medications that target different pathologic processes, combination therapy has become a frequently used therapeutic option in PAH. In this paper, we aimed to review the therapeutic algorithms in pulmonary hypertension based on current guidelines. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of modeling the timing error process in magnetic recording systems. We propose a discrete- valued Markov model for the timing error process, and design two methods (data-aided and nondata-aided), based on the Baum-Welch algorithm, to extract the model parameters from the readback waveforms. The channel model we consider is an intersymbol interference (ISI) channel with additive Gaussian noise. The continuous-time readback signal at the output of the channel is sampled at baud-rate. Simulation results show that the estimated parameters are close to the actual values and the convergence is attained in a few iterations of the Baum-Welch algorithm. We also demonstrate the usefulness of the accurate model extraction by comparing a fine-tuned Markov timing recovery loop to the standard Mueller and Muller detector with a tuned second-order loop filter. [ABSTRACT FROM AUTHOR]

The article presents information on the properties of Graeco-Latin squares enumerated by mathematician Leonhard Euler. Euler suggested that a Graeco-Latin square of size n could never exist for any n of the form 4k +2, although he was not able to prove it. A Latin square is an n-by-n array of n distinct symbols in which each symbol appears exactly once in each row and column. On the other hand a Graeco-Latin square is an n-by-n array of ordered pairs from a set of n symbols such that in each row and each column of the array, each symbol appears exactly once in each coordinate. In one of his papers on Graeco-Latin squares, Euler used magic squares, which are closely related to Graeco-Latin squares. Magic squares were constructed by using Graeco-Latin squares of orders 3, 4 and 5. He showed that a Graeco-Latin square of order n can be converted into a magic square by the use of an algorithm. One can construct Graeco-Latin squares of every order n except those values for which the prime factorization of n contains only a single factor of 2.