Circular Block Research Articles

Determination of dissipative Dyakonov surface waves using a finite element method based eigenvalue algorithm.

A full-vectorial finite element method is developed to analyze the surface waves propagating at the interface between two media which could be dissipative particularly. The dissipative wave possessing a complex-valued propagation constant can be determined precisely for any given propagation direction and thus the property of losses could be thoroughly analyzed. Besides, by applying a special characteristic of the implicit circular block matrix, we reduce the computational consumptions in the analysis. By utilizing this method, the Dyakonov surface wave (DSW) at the interface between a dielectric and a metal-dielectric multilayered (MDM) structure which serves as a hyperbolic medium is discussed. Its propagation loss is smaller for larger period of the MDM structure but its field becomes less confined to the interface.

A note on circular neighbor balanced designs

ABSTRACTThis paper describes some methods of constructing circular neighbor balanced and circular partially neighbor balanced block designs for estimation of direct and neighbor effects of the treatments. A class of circular neighbor balanced block designs with unequal block sizes is also proposed.

On estimation of limiting variance of partial sums of functions of associated random variables

We discuss three different estimators for estimating the limiting variance of partial sums of functions of associated random variables. The first two estimators are based on a Subsampling method, while the third is obtained using Circular block bootstrap. As an application, we also obtain estimators for the limiting variance for U-statistics based on stationary associated random variables.

Exact Zernike and pseudo-Zernike moments image reconstruction based on circular overlapping blocks and Chamfer distance

This study aims to explore a novel approach to reconstruct multi-gray-level images based on circular blocks reconstruction method using two exact and fast moments: Zernike (CBR-EZM) and pseudo-Zernike (CBR-EPZM): An image is first divided into a set of sub-images which are then reconstructed independently. We also introduced Chamfer distance (CD) to capitalize on the use of discrete distance instead of Euclidean one. The combination of our methods and CD leads to CBR-EZM-CD and CBR-EPZM-CD methods. Obviously, image partitioning offers significant advantages, but an undesirable circular blocking effect can occur. To mitigate this effect, we have implemented overlapping feature to our new methods leading to OCBR-EZM-CD and OCBR-EPZM-CD, by exploiting neighborhood information of the circular blocks. The main motivation of this novel approach is to explore new applications of Zernike and pseudo-Zernike moments. One of the fields is feature extraction for pattern recognition: Zernike and pseudo-Zernike moments are well known to capture only the global features, but thanks to the circular block reconstruction, we can now use those moments to extract also local features.

Optimal block designs with non additive mixed effects interference

ABSTRACTThis paper deals with optimality aspects of block designs balanced for interference effects from neighboring units on both sides under a general non additive model along with random block effects. Here, a class of complete, circular block designs strongly balanced for interference effects has been shown to be universally optimal for the estimation of direct effects and interference effects (left and right) of treatments under a non additive mixed effects model.

Experimental and Analytical Examination in Mortar Hollow Circular Cylinder Block for Heat Storage

Experimental and Analytical Examination in Mortar Hollow Circular Cylinder Block for Heat Storage

A new block-based method for copy move forgery detection under image geometric transforms

Copy move forgery detection (CMFD) is one of the most active subtopic in forgery scheme. The methods of CMFD are divided into to block-based method and keypoint-based method in general. Compared with keypoint-based method, block-based method can detect undetectable detail without morphology segmentation. But many block-based methods detect the plain copy-move forgeries only. They have been incompetent to detect the post-processing operations such as various geometrical distortions, and then fail to detect the forgery regions accurately. Therefore, this paper presents an improved block-based efficient method for CMFD. Firstly, after pre-processing, an auxiliary overlapped circular block is presented to divide the forged image into overlapped circular blocks. The local and inner image feature is extracted by the Discrete Radial Harmonic Fourier Moments (DRHFMs) with the overlapped circular block from the suspicious image. Then, the similar feature vectors of blocks are searched by 2 Nearest Neighbors (2NN) test. Euclidean distance and correlation coefficient is employed to filter these features and then remove the false matches. Morphologic operation is employed to delete the isolated pixels. A series of experiments are done to analyze the performance for CMFD. Experimental results show that the new DRHFMs can obtain outstanding performance even under image geometrical distortions.

Robust copy–move forgery detection using quaternion exponent moments

The detection of forgeries in color images is a very important topic in forensic science. Copy–move (or copy–paste) forgery is the most common form of tampering associated with color images. Conventional copy–move forgeries detection techniques usually suffer from the problems of false positives and susceptibility to many signal processing operations. It is a challenging work to design a robust copy–move forgery detection method. In this paper, we present a novel block-based robust copy–move forgery detection approach using invariant quaternion exponent moments (QEMs). Firstly, original tempered color image is preprocessed with Gaussian low-pass filter, and the filtered color image is divided into overlapping circular blocks. Then, the accurate and robust feature descriptor, QEMs modulus, is extracted from color image block holistically as a vector field. Finally, exact Euclidean locality sensitive hashing is utilized to find rapidly the matching blocks, and the falsely matched block pairs are removed by customizing the random sample consensus with QEMs magnitudes differences. Extensive experimental results show the efficacy of the newly proposed approach in detecting copy–paste forgeries under various challenging conditions, such as noise addition, lossy compression, scaling, and rotation. We obtain the average forgery detection accuracy (F-measure) in excess of 96 and 88% across postprocessing operations, at image level and at pixel level, respectively.

Addressing huge spatial heterogeneity induced by virus infections in lentil breeding trials.

BackgroundSpatial heterogeneity can have serious effects on the precision of field experimentation in plant breeding. In the present study the capacity of the honeycomb design (HD) to sample huge spatial heterogeneity was appraised. For this purpose, four trials were conducted each comprising a lentil landrace being screened for response to viruses.ResultsHuge spatial heterogeneity was reflected by the abnormally high values for coefficient of variation (CV) of single-plant yields, ranging 123–162 %. At a given field area, increasing the number of simulated entries was followed by declined effectiveness of the method, on account of the larger circular block implying greater intra-block heterogeneity; a hyperbolic increasing pattern of the top to bottom entry mean gap (TBG) indicated that a number of more than 100 replicates (number of plants per entry) is the crucial threshold to avoid significant deterioration of the sampling degree. Nevertheless, the honeycomb model kept dealing with variation better than the randomized complete block (RCB) pattern, thanks to the circular shape and standardized type of block that ensure the less possible extra heterogeneity with expanding the area of the block.ConclusionsOwing to the even and systematic entry allocation, breeders do not need to be concerned with the extra spatial heterogeneity that might induce the extra surface needed to expand the size of the block when many entries are considered. Instead, they could improve accuracy of comparisons with increasing the number of replicates (circular blocks) despite the concomitant greater overall spatial heterogeneity.

Non binary partially neighbor balanced designs for circular blocks

ABSTRACTNeighbor designs are recommended for the cases where the performance of treatment is affected by the neighboring treatments as in biometrics and agriculture. In this paper we have constructed two new series of non binary partially neighbor balanced designs for v = 2n and v = 2n+1 number of treatments, respectively. The blocks in the design are non binary and circular but no treatment is ever a neighbor to itself. The designs proposed here are partially balanced in terms of nearest neighbors. No such series are known in the literature.

First and second order analysis for periodic random arrays using block bootstrap methods

In the paper row-wise periodically correlated triangular arrays are considered. The period length is assumed to grow in time. The Fourier decomposition of the mean and autocovariance functions for each row of the matrix is presented. To construct bootstrap estimators of the Fourier coefficients two block bootstrap techniques are used. These are the circular version of the Generalized Seasonal Block Bootstrap and the Circular Block Bootstrap. Consistency results for both methods are presented. Bootstrap-t equal-tailed confidence intervals for parameters of interest are constructed. Results are illustrated by an example based on simulated data.

Characterization of Hydroxyapatite Coated SS316L for Biomedical Application

This paper focuses on characterization of Hydroxyapatite coated SS316 L using Pulse vapour deposition method. The target material (Hydroxyapatite) has been synthesised chemically in laboratory through the addition of (NH4)2HPO4 with Ca (NO3)24H2O solution. This mixture has been converted in to circular blocks through various processes as explained below and coated over the stainless steel substrate. The morphological characteristics of the coating and surface roughness analysis have done through SEM and AFM. Also the hardness and corrosion resistance of the coating are examined. It has been found that improved hardness when compared with SS316L (175 Hv) to Hydroxyapatite (245 Hv) coated SS316 L. Also the results of corrosion resistance test after 250 Hrs of experiment found that formation of red rust is attained for uncoated samples where as Hydroxyapatite coated samples remains unchanged.

PCET based copy-move forgery detection in images under geometric transforms

With the advent of the powerful editing software and sophisticated digital cameras, it is now possible to manipulate images. Copy-move is one of the most common methods for image manipulation. Several methods have been proposed to detect and locate the tampered regions, while many methods failed when the copied region undergone some geometric transformations before being pasted, because of the de-synchronization in the searching procedure. This paper presents an efficient technique for detecting the copy-move forgery under geometric transforms. Firstly, the forged image is divided into overlapping circular blocks, and Polar Complex Exponential Transform (PCET) is employed to each block to extract the invariant features, thus, the PCET kernels represent each block. Secondly, the Approximate Nearest Neighbor (ANN) Searching Problem is used for identifying the potential similar blocks by means of locality sensitive hashing (LSH). In order to make the algorithm more robust, morphological operations are applied to remove the wrong similar blocks. Experimental results show that our proposed technique is robust to geometric transformations with low computational complexity.

Change Point Analysis of Exchange Rates Using Bootstrapping Methods: An Application to the Indonesian Rupiah 2000–2008

In this paper, we investigate detecting single change point under time series regression model with GARCH errors using the cumulative sum of squares of the least squares residuals test and the log-likelihood ratio test. Furthermore we think it is important to calculate confidence interval for an estimated change point, for which we need to know the sampling distribution of the estimated change point. We obtain the sampling distribution to calculate confidence interval using Monte Carlo simulation based on a circular block bootstrap method and verify the performance of the above break point tests by Monte Carlo experiment. Then we detect a change point in the exchange rate of Indonesian Rupiah (IDR) using the above test to detect. The Government of Indonesia officially announced (de jure) to adopt a floating exchange rate regime in August 1997. However, from time to time, Bank Indonesia nevertheless maintains the stability of rupiah value in the market. Since there is no official information regarding on central bank’s intervention in the foreign exchange market, therefore detecting a structural change in the time series of the exchange market can be used as an indicator of exchange rate management. Our real data analysis shows that the IDR had been moving with the USD since 2000, but that the direction of the relationship changed in March 2002. This indicates that there was some control over the Rupiah’s movement.

Role of Laminar Length of Round Jet Impinging on Metal Foams

Impingement heat transfer in a circular block of an open-cell metal foam with high porosity () is experimentally studied at two distinctive flow regimes, semiturbulent ( and 2800) and fully turbulent ( and 15,000) regimes. The influence of jet structures and their variation with jet exit-to-foam spacing (impinging distance) on overall heat transfer are characterized. The laminar length appears in the semiturbulent jet but disappears in the fully turbulent jet. Its role is found to longitudinally translate the onset axial location of entrainment, which coincides with the potential core of the round jet. When the metal foam is positioned inside the laminar length, the overall heat transfer becomes insensitive to the impinging distance. A wider divergence of the semiturbulent jet and a faster decay of the axial momentum than the fully turbulent jet occur once entrainment takes place.

Experimental Investigation on Heat Transfer Enhancement from a Channel Mounted with Staggered Blocks

The present work experimentally investigates heat transfer enhancement from a channel mounted with staggered blocks. The effect of the geometrical parameters, such as the square and circular shapes of the blocks and the ratio of the centre to centre spacing between the blocks (Lx/Ly ratio) along the stream-wise direction and transverse direction of flow, has been investigated. Experiments were conducted using the newly developed experimental setup for Reynolds number ranging from 100 to 500 based on the hydraulic diameter and the average velocity of flow through the channel. The heat input values varied from 100 to 300 W with a step of 50 W, and water was used as working fluid. The results suggest that the variation of the Reynolds number significantly influenced the heat transfer enhancement compared with other geometrical parameters. The square- shaped block imposed greater impact on the heat transfer than the circular blocks. An increase in the heat transfer was observed while increasing the Lx/Ly ratios from 1.5 to 2.5 for the square blocks, whereas it was reduced for the circular blocks.

Block Bootstrap for Poisson‐Sampled Almost Periodic Processes

Let be an almost periodically correlated process and {N(t),t≥0} be a homogeneous Poisson process and {Tk,k≥1} be its jump moments. We assume that and {N(t),t≥0} are independent. Moreover, the process is not observed continuously but only in the time moments {Tk,k≥1}; In this paper, we focus on the estimation of the cyclic means of . The asymptotic normality of the rescaled error of the estimator is shown. Additionally, the bootstrap method based on the circular block bootstrap is proposed. The consistency of the bootstrap technique is proved, and the bootstrap pointwise and simultaneous confidence intervals for the cyclic means are constructed. The results are illustrated by a simulated data example.

Effect of Temperature on Growth and Sporulation of Botrytis fabae, and Resistance Reactions of Faba Bean against the Pathogen

Chocolate spot (Botrytis fabae) is a devastating disease of faba bean and reduces its production and productivity. Three controlled condition experiments were conducted to assess the effect of temperature on growth and sporulation of B. fabae, and faba bean resistance reaction against the pathogen using a single B. fabae isolate and Degaga and Bulga-70 faba bean varieties. For cultural experiment, a circular block of actively growing B. fabae mycelia was placed on faba bean dextrose agar medium and arranged in a completely randomized design (CRD) with four replications. For resistance reaction evaluation, fresh culture of isolate suspension was prepared (2 × 105 spores ml-1) and inoculated on to three weeks-old faba bean seedling detached leaves and the whole plant. Inoculated leaflets and seedlings were factorial arranged in a CRD with four replications. Both sets were incubated at 20, 22, 24 and 26°C. The maximum (84.00 mm) radial growth on 5 days after inoculation (DAI); average conidial size (24.86 × 16.32 μm), sporulation (2.48 × 103 conidia ml-1) on 12DAI and growth rate (1.058 mm day-1) were recorded at 22°C. The least values of these parameters and nil sporulation were obtained from 26°C. The highest average lesion size (17.67 mm in Degaga and 22.83 mm in Bulga-70), AUDPC for lesion sizes (30.92 mm in Degaga and 42.08 mm in Bulga-70) and severity (2.13 score) values were recorded at 22°C on 5DAI in detached leaf test. Infection and disease development was reduced at 26°C. The trend was similar in the whole plant test. Such parameters were linearly increased with temperature to maximum and declined progressively in both reaction evaluation tests. The two evaluation experiments indicated that the optimum temperature for B. fabae growth, sporulation, infection and disease development was at 22°C.

Some Classes of Binary Block Neighbor Designs

Neighbor designs are useful to neutralize the neighbor effects. In this paper two classes of these designs are constructed in circular binary blocks of size 4, 8, …, 24. First class consists of six infinite series of nearest neighbor designs in which each pair of distinct treatments appears once as neighbors. Second class also deals with six infinite series of these designs in which each pair of distinct treatments appears twice as neighbors. A catalog of nearest neighbor designs is also compiled in circular binary blocks for odd number of treatments from 23 to 99.

On the Optimality of Circular Block Designs Under a Mixed Interference Model

Filipiak and Markiewicz (2012) proved the universal optimality of circular weakly neighbor balanced designs (CWNBDs) under the interference model with fixed neighbor effects among the class of complete block designs. In two special cases where a CWNBD cannot exist, Filipiak et al. (2012) characterized D-optimal designs. The aim of this paper is to show the universal optimality of CWNBDs and to characterize D-optimal designs under the interference model with random neighbor effects.