Algorithms

12 pages, 2676 KiB

Open AccessArticle

Efficient Deep Learning-Based Automated Pathology Identification in Retinal Optical Coherence Tomography Images

by Qingge Ji, Wenjie He, Jie Huang and Yankui Sun

Algorithms 2018, 11(6), 88; https://doi.org/10.3390/a11060088 - 20 Jun 2018

Cited by 24 | Viewed by 5615

We present an automatic method based on transfer learning for the identification of dry age-related macular degeneration (AMD) and diabetic macular edema (DME) from retinal optical coherence tomography (OCT) images. The algorithm aims to improve the classification performance of retinal OCT images and [...] Read more.

We present an automatic method based on transfer learning for the identification of dry age-related macular degeneration (AMD) and diabetic macular edema (DME) from retinal optical coherence tomography (OCT) images. The algorithm aims to improve the classification performance of retinal OCT images and shorten the training time. Firstly, we remove the last several layers from the pre-trained Inception V3 model and regard the remaining part as a fixed feature extractor. Then, the features are used as input of a convolutional neural network (CNN) designed to learn the feature space shifts. The experimental results on two different retinal OCT images datasets demonstrate the effectiveness of the proposed method. Full article

(This article belongs to the Special Issue Machine Learning for Medical Image Analysis)

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4 pages, 157 KiB

Open AccessEditorial

Special Issue on Algorithms for Scheduling Problems

by Frank Werner, Larysa Burtseva and Yuri N. Sotskov

Algorithms 2018, 11(6), 87; https://doi.org/10.3390/a11060087 - 20 Jun 2018

Cited by 4 | Viewed by 4623

Abstract

This special issue of Algorithms is devoted to the development of scheduling algorithms based on innovative approaches for solving hard scheduling problems either exactly or approximately. Submissions were welcome both for traditional scheduling problems as well as for new practical applications. The main [...] Read more.

This special issue of Algorithms is devoted to the development of scheduling algorithms based on innovative approaches for solving hard scheduling problems either exactly or approximately. Submissions were welcome both for traditional scheduling problems as well as for new practical applications. The main topics include sequencing and scheduling with additional constraints (setup times or costs, precedence constraints, resource constraints, and batch production environment) and production planning and scheduling problems arising in real-world applications. Full article

(This article belongs to the Special Issue Algorithms for Scheduling Problems)

23 pages, 2958 KiB

Open AccessArticle

Performance Optimal PI controller Tuning Based on Integrating Plus Time Delay Models

by Christer Dalen and David Di Ruscio

Algorithms 2018, 11(6), 86; https://doi.org/10.3390/a11060086 - 17 Jun 2018

Cited by 13 | Viewed by 5225

Abstract

A method for tuning PI controller parameters, a prescribed maximum time delay error or a relative time delay error is presented. The method is based on integrator plus time delay models. The integral time constant is linear in the relative time delay error, [...] Read more.

A method for tuning PI controller parameters, a prescribed maximum time delay error or a relative time delay error is presented. The method is based on integrator plus time delay models. The integral time constant is linear in the relative time delay error, and the proportional constant is seen inversely proportional to the relative time delay error. The keystone in the method is the method product parameter, i.e., the product of the PI controller proportional constant, the integral time constant, and the integrator plus time delay model, velocity gain. The method product parameter is found to be constant for various PI controller tuning methods. Optimal suggestions are given for choosing the method product parameter, i.e., optimal such that the integrated absolute error or, more interestingly, the Pareto performance objective (i.e., integrated absolute error for combined step changes in output and input disturbances) is minimised. Variants of the presented tuning method are demonstrated for tuning PI controllers for motivated (possible) higher order process model examples, i.e., the presented method is combined with the model reduction step (process–reaction curve) in Ziegler–Nichols. Full article

(This article belongs to the Special Issue Algorithms for PID Controller)

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20 pages, 2157 KiB

Open AccessArticle

ILC with Initial State Learning for Fractional Order Linear Distributed Parameter Systems

by Yong-Hong Lan and Zhe-Min Cui

Algorithms 2018, 11(6), 85; https://doi.org/10.3390/a11060085 - 14 Jun 2018

Cited by 2 | Viewed by 4627

Abstract

This paper presents a second order P-type iterative learning control (ILC) scheme with initial state learning for a class of fractional order linear distributed parameter systems. First, by analyzing the control and learning processes, a discrete system for P-type ILC is established, and [...] Read more.

This paper presents a second order P-type iterative learning control (ILC) scheme with initial state learning for a class of fractional order linear distributed parameter systems. First, by analyzing the control and learning processes, a discrete system for P-type ILC is established, and the ILC design problem is then converted to a stability problem for such a discrete system. Next, a sufficient condition for the convergence of the control input and the tracking errors is obtained by introducing a new norm and using the generalized Gronwall inequality, which is less conservative than the existing one. Finally, the validity of the proposed method is verified by a numerical example. Full article

(This article belongs to the Special Issue Fractional Order Systems and Signals: Modelling, Identification and Control Applications)

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19 pages, 333 KiB

Open AccessArticle

Efficient Approximation for Restricted Biclique Cover Problems

by Alessandro Epasto and Eli Upfal

Algorithms 2018, 11(6), 84; https://doi.org/10.3390/a11060084 - 12 Jun 2018

Cited by 3 | Viewed by 5157

Abstract

Covering the edges of a bipartite graph by a minimum set of bipartite complete graphs (bicliques) is a basic graph theoretic problem, with numerous applications. In particular, it is used to characterize parsimonious models of a set of observations (each biclique corresponds to [...] Read more.

Covering the edges of a bipartite graph by a minimum set of bipartite complete graphs (bicliques) is a basic graph theoretic problem, with numerous applications. In particular, it is used to characterize parsimonious models of a set of observations (each biclique corresponds to a factor or feature that relates the observations in the two sets of nodes connected by the biclique). The decision version of the minimum biclique cover problem is NP-Complete, and unless

P = N P

, the cover size cannot be approximated in general within less than a sub-linear factor of the number of nodes (or edges) in the graph. In this work, we consider two natural restrictions to the problem, motivated by practical applications. In the first case, we restrict the number of bicliques a node can belong to. We show that when this number is at least 5, the problem is still NP-hard. In contrast, we show that when nodes belong to no more than two bicliques, the problem has efficient approximations. The second model we consider corresponds to observing a set of independent samples from an unknown model, governed by a possibly large number of factors. The model is defined by a bipartite graph

G = (L, R, E)

, where each node in L is assigned to an arbitrary subset of up to a constant f factors, while the nodes in R (the independent observations) are assigned to random subsets of the set of k factors where k can grow with size of the graph. We show that this practical version of the biclique cover problem is amenable to efficient approximations. Full article

(This article belongs to the Special Issue Algorithms for Hard Problems: Approximation and Parameterization)

12 pages, 2733 KiB

Open AccessArticle

A Combined Syntactical and Statistical Approach for R Peak Detection in Real-Time Long-Term Heart Rate Variability Analysis

by David Pang and Tomohiko Igasaki

Algorithms 2018, 11(6), 83; https://doi.org/10.3390/a11060083 - 7 Jun 2018

Cited by 2 | Viewed by 5003

Abstract

Long-term heart rate variability (HRV) analysis is useful as a noninvasive technique for autonomic nervous system activity assessment. It provides a method for assessing many physiological and pathological factors that modulate the normal heartbeat. The performance of HRV analysis systems heavily depends on [...] Read more.

Long-term heart rate variability (HRV) analysis is useful as a noninvasive technique for autonomic nervous system activity assessment. It provides a method for assessing many physiological and pathological factors that modulate the normal heartbeat. The performance of HRV analysis systems heavily depends on a reliable and accurate detection of the R peak of the QRS complex. Ectopic beats caused by misdetection or arrhythmic events can introduce bias into HRV results, resulting in significant problems in their interpretation. This study presents a novel method for long-term detection of normal R peaks (which represent the normal heartbeat in electrocardiographic signals), intended specifically for HRV analysis. The very low computational complexity of the proposed method, which combines and exploits the advantages of syntactical and statistical approaches, enables real-time applications. The approach was validated using the Massachusetts Institute of Technology–Beth Israel Hospital Normal Sinus Rhythm and the Fantasia database, and has a sensitivity, positive predictivity, detection error rate, and accuracy of 99.998, 99.999, 0.003, and 99.996%, respectively. Full article

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Figure 1
A typical electrocardiography (ECG) waveform and RR interval. Full article ">Figure 2
Block diagram of ECG signal processing. Full article ">Figure 3
Vectorization process. Full article ">Figure 4
Final result of the vectorization and noise-removal processes. Full article ">Figure 5
(a) Relation of the ECG signal sequence to the automata states and other ECG parameters and (b) the automata’s state transition diagram. Full article ">Figure 6
Occurrence of the signal noted as an “isolated QRS-like artefact” in record #16272 [<a href="#B12-algorithms-11-00083" class="html-bibr">12</a>,<a href="#B13-algorithms-11-00083" class="html-bibr">13</a>,<a href="#B15-algorithms-11-00083" class="html-bibr">15</a>]. Full article ">Figure 7
(a, b, and c) Typical waveforms, which sometimes occurred and were annotated as beats in the Fantasia database, but cannot be recognized by the automata as heartbeats [<a href="#B12-algorithms-11-00083" class="html-bibr">12</a>,<a href="#B13-algorithms-11-00083" class="html-bibr">13</a>,<a href="#B14-algorithms-11-00083" class="html-bibr">14</a>,<a href="#B15-algorithms-11-00083" class="html-bibr">15</a>]. Full article ">Figure 8
A single misdetection of the R peak results in wrong NN intervals, which can greatly modify the result of the frequency analysis of the HRV as compared to the actual analysis without misdetection. Full article ">

18 pages, 4389 KiB

Open AccessArticle

Research on Fault Diagnosis of a Marine Fuel System Based on the SaDE-ELM Algorithm

by Yi Wei and Yaokun Yue

Algorithms 2018, 11(6), 82; https://doi.org/10.3390/a11060082 - 7 Jun 2018

Cited by 8 | Viewed by 4839

Abstract

Since the traditional fault diagnosis method of the marine fuel system has a low accuracy of identification, the algorithm solution can easily fall into local optimum, and they are not fit for the research on the fault diagnosis of a marine fuel system. [...] Read more.

Since the traditional fault diagnosis method of the marine fuel system has a low accuracy of identification, the algorithm solution can easily fall into local optimum, and they are not fit for the research on the fault diagnosis of a marine fuel system. Hence, a fault diagnosis method for a marine fuel system based on the SaDE-ELM algorithm is proposed. First, the parameters of initializing extreme learning machine are adopted by a differential evolution algorithm. Second, the fault diagnosis of the marine fuel system is realized by the fault diagnosis model corresponding to the state training of marine fuel system. Based on the obtained fault data of a marine fuel system, the proposed method is verified. The experimental results show that this method produces higher recognition accuracy and faster recognition speed that are superior to the traditional BP neural network, SVM support vector machine diagnosis algorithm, and the un-optimized extreme learning machine algorithm. The results have important significance relevant to fault diagnosis for a marine fuel system. The algorithm based on SaDE-ELM is an effective and practical method of fault diagnosis for a marine fuel system. Full article

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15 pages, 262 KiB

Open AccessArticle

A Randomized Algorithm for Optimal PID Controllers

by Yossi Peretz

Algorithms 2018, 11(6), 81; https://doi.org/10.3390/a11060081 - 5 Jun 2018

Cited by 9 | Viewed by 4021

Abstract

A randomized algorithm is suggested for the syntheses of optimal PID controllers for MIMO coupled systems, where the optimality is with respect to the

H_{\infty}

-norm, the

H_{2}

-norm and the LQR functional, with possible system-performance specifications defined by regional pole-placement. [...] Read more.

A randomized algorithm is suggested for the syntheses of optimal PID controllers for MIMO coupled systems, where the optimality is with respect to the

H_{\infty}

-norm, the

H_{2}

-norm and the LQR functional, with possible system-performance specifications defined by regional pole-placement. Other notions of optimality (e.g., mixed

H_{2} / H_{\infty}

design, controller norm or controller sparsity) can be handled similarly with the suggested algorithm. The suggested method is direct and thus can be applied to continuous-time systems as well as to discrete-time systems with the obvious minor changes. The presented algorithm is a randomized algorithm, which has a proof of convergence (in probability) to a global optimum. Full article

(This article belongs to the Special Issue Algorithms for PID Controller)

16 pages, 293 KiB

Open AccessFeature PaperArticle

Scheduling a Single Machine with Primary and Secondary Objectives

by Nodari Vakhania

Algorithms 2018, 11(6), 80; https://doi.org/10.3390/a11060080 - 5 Jun 2018

Cited by 6 | Viewed by 4040

Abstract

We study a scheduling problem in which jobs with release times and due dates are to be processed on a single machine. With the primary objective to minimize the maximum job lateness, the problem is strongly NP-hard. We describe a general algorithmic scheme [...] Read more.

We study a scheduling problem in which jobs with release times and due dates are to be processed on a single machine. With the primary objective to minimize the maximum job lateness, the problem is strongly NP-hard. We describe a general algorithmic scheme to minimize the maximum job lateness, with the secondary objective to minimize the maximum job completion time. The problem of finding the Pareto-optimal set of feasible solutions with these two objective criteria is strongly NP-hard. We give the dominance properties and conditions when the Pareto-optimal set can be formed in polynomial time. These properties, together with our general framework, provide the theoretical background, so that the basic framework can be expanded to (exponential-time) implicit enumeration algorithms and polynomial-time approximation algorithms (generating the Pareto sub-optimal frontier with a fair balance between the two objectives). Some available in the literature experimental results confirm the practical efficiency of the proposed framework. Full article

(This article belongs to the Special Issue Algorithms for Scheduling Problems)

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19 pages, 1961 KiB

Open AccessArticle

A Fire Detection Algorithm Based on Tchebichef Moment Invariants and PSO-SVM

by Yongming Bian, Meng Yang, Xuying Fan and Yuchao Liu

Algorithms 2018, 11(6), 79; https://doi.org/10.3390/a11060079 - 25 May 2018

Cited by 16 | Viewed by 5061

Abstract

Automatic fire detection, which can detect and raise the alarm for fire early, is expected to help reduce the loss of life and property as much as possible. Due to its advantages over traditional methods, image processing technology has been applied gradually in [...] Read more.

Automatic fire detection, which can detect and raise the alarm for fire early, is expected to help reduce the loss of life and property as much as possible. Due to its advantages over traditional methods, image processing technology has been applied gradually in fire detection. In this paper, a novel algorithm is proposed to achieve fire image detection, combined with Tchebichef (sometimes referred to as Chebyshev) moment invariants (TMIs) and particle swarm optimization-support vector machine (PSO-SVM). According to the correlation between geometric moments and Tchebichef moments, the translation, rotation, and scaling (TRS) invariants of Tchebichef moments are obtained first. Then, the TMIs of candidate images are calculated to construct feature vectors. To gain the best detection performance, a PSO-SVM model is proposed, where the kernel parameter and penalty factor of support vector machine (SVM) are optimized by particle swarm optimization (PSO). Then, the PSO-SVM model is utilized to identify the fire images. Compared with algorithms based on Hu moment invariants (HMIs) and Zernike moment invariants (ZMIs), the experimental results show that the proposed algorithm can improve the detection accuracy, achieving the highest detection rate of 98.18%. Moreover, it still exhibits the best performance even if the size of the training sample set is small and the images are transformed by TRS. Full article

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The schematic diagram of support vector machine (SVM) classification. Full article ">Figure 2
The flow diagram of particle swarm optimization-support vector machine (PSO-SVM) model construction. Full article ">Figure 3
The flow diagram of fire image detection based on the PSO-SVM model. Full article ">Figure 4
Candidate images: (a–c) stable burning of fire; (d–f) initial extinguishing of fire; (g–i) final extinguishing of fire. Full article ">Figure 5
The fitness curve of particle swarm optimization. Full article ">Figure 6
Effect of training dataset size on recognition rate. Full article ">Figure 7
Images transformed by translation, rotation, and scaling (TRS). (a) Original image; (b) image translated with [−70, −50]; (c) image translated with [50, 70]; (d) image rotated by <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>15</mn> </mrow> <mo>∘</mo> </msup> </mrow> </semantics></math>; (e) image rotated by <math display="inline"><semantics> <mrow> <mo>−</mo> <msup> <mrow> <mn>15</mn> </mrow> <mo>∘</mo> </msup> </mrow> </semantics></math>; (f) image scaled with 0.8; (g) image scaled with 1.2. Full article ">

21 pages, 1142 KiB

Open AccessArticle

A Modified Artificial Bee Colony Algorithm Based on the Self-Learning Mechanism

by Bao Pang, Yong Song, Chengjin Zhang, Hongling Wang and Runtao Yang

Algorithms 2018, 11(6), 78; https://doi.org/10.3390/a11060078 - 24 May 2018

Cited by 9 | Viewed by 4815

Abstract

Artificial bee colony (ABC) algorithm, a novel category of bionic intelligent optimization algorithm, was achieved for solving complex nonlinear optimization problems. Previous studies have shown that ABC algorithm is competitive to other biological-inspired optimization algorithms, but there still exist several insufficiencies due to [...] Read more.

Artificial bee colony (ABC) algorithm, a novel category of bionic intelligent optimization algorithm, was achieved for solving complex nonlinear optimization problems. Previous studies have shown that ABC algorithm is competitive to other biological-inspired optimization algorithms, but there still exist several insufficiencies due to the inefficient solution search equation (SSE), which does well in exploration but poorly in exploitation. To improve accuracy of the solutions, this paper proposes a modified ABC algorithm based on the self-learning mechanism (SLABC) with five SSEs as the candidate operator pool; among them, one is good at exploration and two of them are good at exploitation; another SSE intends to balance exploration and exploitation; moreover, the last SSE with Lévy flight step-size which can generate smaller step-size with high frequency and bigger step-size occasionally not only can balance exploration and exploitation but also possesses the ability to escape from the local optimum. This paper proposes a simple self-learning mechanism, wherein the SSE is selected according to the previous success ratio in generating promising solutions at each iteration. Experiments on a set of 9 benchmark functions are carried out with the purpose of evaluating the performance of the proposed method. The experimental results illustrated that the SLABC algorithm achieves significant improvement compared with other competitive algorithms. Full article

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Algorithms, Volume 11, Issue 6 (June 2018) – 11 articles

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