Images obtained under low-light conditions tend to have the characteristics of low-grey levels, high-noise levels, and indistinguishable details. Image degradation not only affects the recognition of images, but also ...
详细信息
Images obtained under low-light conditions tend to have the characteristics of low-grey levels, high-noise levels, and indistinguishable details. Image degradation not only affects the recognition of images, but also influences the performance of the computer vision system. The low-light image enhancement algorithm based on the dark channel prior de-hazing technique can enhance the contrast of images effectively and can highlight the details of images. However, the dark channel prior dehazing technique ignores the effects of noise, which leads to significant noise amplification after the enhancement process. In this study, a de-hazing-based simultaneous enhancement and noise reduction algorithm of are proposed by analysing the essence of the dark channel prior de-hazing technique and bilateral filter. First, the authors estimate the values of the initial parameters of the hazy image model by de-hazing technique. Then, they correct the parameters of the hazy image model alternately with the iterative joint bilateral filter. Experimental results indicate that the proposed algorithm can simultaneously enhance the low-light images and reduce noise effectively. The proposed algorithm could also perform quite well compared with the current common image enhancement and noise reduction algorithms in terms of the subjective visual effects and objective quality assessments.
Imperfect data stream leads to tree size explosion and detrimental accuracy problems. Overfitting problem and the imbalanced class distribution reduce the performance of the original decision-tree algorithm for stream...
详细信息
Imperfect data stream leads to tree size explosion and detrimental accuracy problems. Overfitting problem and the imbalanced class distribution reduce the performance of the original decision-tree algorithm for stream mining. In this paper, we propose an incremental optimization mechanism to solve these problems. The mechanism is called Optimized Very Fast Decision Tree (OVFDT) that possesses an optimized node-splitting control mechanism. Accuracy, tree size, and the learning time are the significant factors influencing the algorithm's performance. Naturally a bigger tree size takes longer computation time. OVFDT is a pioneer model equipped with an incremental optimization mechanism that seeks for a balance between accuracy and tree size for data stream mining. It operates incrementally by a test-then-train approach. Three types of functional tree leaves improve the accuracy with which the tree model makes a prediction for a new data stream in the testing phase. The optimized node-splitting mechanism controls the tree model growth in the training phase. The experiment shows that OVFDT obtains an optimal tree structure in both numeric and nominal datasets.
In this paper we consider implementation algorithms and applications of the discretization method for diffusion equations on polygonal (2D) and polyhedral (3D) meshes recently proposed by one of the authors in [11]. T...
详细信息
In this paper we consider implementation algorithms and applications of the discretization method for diffusion equations on polygonal (2D) and polyhedral (3D) meshes recently proposed by one of the authors in [11]. The discretization method is based on the approximation of fluxes in the mixed finite element method by appropriate piecewise constant vector functions inside the mesh cells. The new piecewise constant fluxes are discontinuous inside the mesh cells but their normal components are continuous on the interfaces between neighbouring cells. Numerical results are given for test problems relevant to applications in reservoir simulation and basin modelling.
Mathematical models and numerical algorithms of substance transport over a closed graph of a cardiovascular system must, satisfy the property of conservativity. A conservative model and a numerical algorithm for calcu...
详细信息
Mathematical models and numerical algorithms of substance transport over a closed graph of a cardiovascular system must, satisfy the property of conservativity. A conservative model and a numerical algorithm for calculation of substance transport through a working heart are proposed in the paper. The efficiency of the algorithm considered here is confirmed by test calculations. A method for simulation of substance transport in tissues surrounding vessels is also proposed.
We analyze a multiserver queueing system with a finite buffer and impatient customers. The arrival customer flow is assumed to be Markovian. Service times of each server are phase-type distributed. If all servers are ...
详细信息
We analyze a multiserver queueing system with a finite buffer and impatient customers. The arrival customer flow is assumed to be Markovian. Service times of each server are phase-type distributed. If all servers are busy and a new arrival occurs, it enters the buffer with a probability depending on the total number of customers in the system and waits for service, or leaves the system with the complementary probability. A waiting customer may become impatient and abandon the system. We give an algorithm for finding the stationary distribution of system states and derive formulas for basic performance characteristics. We find Laplace-Stieltjes transforms for sojourn and waiting times. Numeric examples are given.
Large-scale scheduling problems have remained difficult to solve despite the intense research in the area and many successful algorithms. In this paper, a new decomposition algorithm is presented which finds a good fe...
详细信息
Large-scale scheduling problems have remained difficult to solve despite the intense research in the area and many successful algorithms. In this paper, a new decomposition algorithm is presented which finds a good feasible solution even for large-scale problems in a reasonable time. In each iteration, a maximum allowed number of operations is first assigned to available units, then the algorithm alternates between a production quantity maximization step and a production time minimization step in each iteration. The performance of the "rolling operation" algorithm is illustrated using an industrial example.
A new strategy for internal model control (IMC) is proposed using a regression algorithm of quasilinear model with extreme learning machine (QL-ELM). Aimed at the chemical process with nonlinearity, the learning proce...
详细信息
A new strategy for internal model control (IMC) is proposed using a regression algorithm of quasilinear model with extreme learning machine (QL-ELM). Aimed at the chemical process with nonlinearity, the learning process of the internal model and inverse model is derived. The proposed QL-ELM is constructed as a linear ARX model with a complicated nonlinear coefficient. It shows some good approximation ability and fast convergence. The complicated coefficients are separated into two parts. The linear part is determined by recursive least square (RLS), while the nonlinear part is identified through extreme learning machine. The parameters of linear part and the output weights of ELM are estimated iteratively. The proposed internal model control is applied to CSTR process. The effectiveness and accuracy of the proposed method are extensively verified through numerical results.
This paper proposes a novel self-structuring algorithm for the online adaptive fuzzy controller (SA-OAFC). The SA-OAFC capable of adding and deleting inference rules autonomously can start operating with an empty set ...
详细信息
This paper proposes a novel self-structuring algorithm for the online adaptive fuzzy controller (SA-OAFC). The SA-OAFC capable of adding and deleting inference rules autonomously can start operating with an empty set of fuzzy rules based on the desired output and actual output of the system to avoid conventional differential operation. It also takes advantage of the auxiliary fuzzy system to evaluate the approximated results with little information of the plant. The SA-OAFC is characterized by its good engineering approachability, robustness for all kinds of perturbations of the plant, and the ability to perform variable selection among a group of candidate input variables. Moreover, it manages to remarkably reduce the amount of computation and decrease the complexity of the system. This paper demonstrates the capabilities of SA-OAFC by a simulation example and then hardware-in-the-loop (HIL) experiment.
In recent years, a number of image encryption algorithms based oil the permutation-diffusion structure have been proposed. However, the control parameters used in the permutation stage are Usually fixed in the whole e...
详细信息
In recent years, a number of image encryption algorithms based oil the permutation-diffusion structure have been proposed. However, the control parameters used in the permutation stage are Usually fixed in the whole encryption process. which favors attacks. In this paper, a chaos-based image encryption algorithm with variable control parameters is proposed. The control parameters used in the permutation stage and the keystream employed in the diffusion stage are generated from two chaotic maps related to the plain-image. As a result, the algorithm can effectively resist all known attacks against permutation-diffusion architectures. Theoretical analyses and computer simulations both confirm that the new algorithm possesses high security and fast encryption speed for practical image encryption. (C) 2008 Elsevier Ltd. All rights reserved.
暂无评论