|
An adaptive fuzzy filter for coding artifacts removal in video and image
WU Jing, YE Xiu-qing, GU Wei-kang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 841-848.
https://doi.org/10.1631/jzus.2007.A0841
This paper proposes a new adaptive post-filtering algorithm to remove coding artifacts in block-based video coder. The proposed method concentrates on blocking and ringing artifacts removal. For de-blocking, the blocking strength is identified to determine the filtering range, and the maximum quantization parameter of the image is used to adapt the 1D fuzzy filter. For de-ringing, besides the edge detection, a complementary ringing detection method is proposed to locate the neglected ringing blocks, and the gradient threshold is adopted to adjust the parameter of 2D fuzzy filter. Experiments are performed on the MPEG-4 sequences. Compared with other methods, the proposed one achieves better detail preservation and artifacts removal performance with lower computational cost.
|
|
EVCP: a convergence time improved high-speed transport congestion control protocol
LU Guang, WANG Yong-chao, ZHU Miao-liang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 849-856.
https://doi.org/10.1631/jzus.2007.A0849
The Internet evolves to incorporate very-high-bandwidth optical links and more large-delay satellite links. TCP faces new challenges in this unique environment. Theory and experiments showed that TCP becomes inefficient and is prone to be unstable as the per-flow product of bandwidth and latency increases, regardless of the queuing scheme. Variable-structure congestion Control Protocol (VCP) is proposed to address these problems. However, VCP has problem in terms of convergence time, i.e., it takes a long time for a new VCP flow to achieve fair bandwidth allocation if the existing VCP flows have large congestion windows. This paper proposed an Extended Variable-structure congestion Control Protocol (EVCP), which adopted a convergence controller. The basic idea of convergence controller is that if a flow has larger window than its fair window, its congestion window should be decreased more aggressively than usual in Multiplicative Decrease (MD) phase. Simulations showed that EVCP has better performance in terms of convergence time while keeping the advantages of VCP.
|
|
Estimation of vegetation biophysical parameters by remote sensing using radial basis function neural network
YANG Xiao-hua, HUANG Jing-feng, WANG Jian-wen, WANG Xiu-zhen, LIU Zhan-yu
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 883-895.
https://doi.org/10.1631/jzus.2007.A0883
Hyperspectral reflectance (350~2500 nm) data were recorded at two different sites of rice in two experiment fields including two cultivars, and three levels of nitrogen (N) application. Twenty-five Vegetation Indices (VIs) were used to predict the rice agronomic parameters including Leaf Area Index (LAI, m2 green leaf/m2 soil) and Green Leaf Chlorophyll Density (GLCD, mg chlorophyll/m2 soil) by the traditional regression models and Radial Basis Function Neural Network (RBF). RBF emerged as a variant of Artificial Neural Networks (ANNs) in the late 1980’s. A large variety of training algorithms has been tested for training RBF networks. In this study, Original RBF (ORBF), Gradient Descent RBF (GDRBF), and Generalized Regression Neural Network (GRNN) were employed. Results showed that green waveband Normalized Difference Vegetation Index (NDVIgreen) and TCARI/OSAVI have the best prediction power for LAI by exponent model and ORBF respectively, and that TCARI/OSAVI has the best prediction power for GLCD by exponent model and GDRBF. The best performances of RBF are compared with the traditional models, showing that the relationship between VIs and agronomic variables are further improved when RBF is used. Compared with the best traditional models, ORBF using TCARI/OSAVI improves the prediction power for LAI by lowering the Root Mean Square Error (RMSE) for 0.1119, and GDRBF using TCARI/OSAVI improves the prediction power for GLCD by lowering the RMSE for 26.7853. It is concluded that RBF provides a useful exploratory and predictive tool when applied to the sensitive VIs.
|
|
Investigation of blood pulse PPG signal regulation on toe effect of body posture and lower limb height
XIN Shang-zhi, HU Sijung, CRABTREE Vincent P., ZHENG Jia, AZORIN-PERIS Vincent, ECHIADIS Angelos, SMITH Peter R.
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 916-920.
https://doi.org/10.1631/jzus.2007.A0916
Objective: To study the regulation of blood pulse volume via photoplethysmography (PPG) signal detected from toe, while the lower limb is passively raised in different height positions. Methods: Use a modified non-invasive PPG technique to detect the blood pulse signal on toe with infrared (IR) photo sensor. A protocol consisting of two postures, i.e., supine and 45° reclining, was designed to conduct laboratory trial in this study. During the period of performing the protocol of these postures, the lower limb was passively raised from the heights of 10 cm to 60 cm randomly and individually with sponge blocks underneath the foot. Results: In the supine posture, the higher the foot was passively raised, the more the blood PPG signal decreased. In the 45° reclining posture, the blood PPG signal increased at the beginning and then decreased in the foot height position from 10 cm to 60 cm. In both postures the normalized AC signal changes significantly while the normalized DC signal changes little. Conclusion: The toe PPG signals can obviously indicate the regulated blood volume change with the designated postural procedures due to the heart level position.
|
|
Bayesian mapping of neural tube defects prevalence in Heshun County, Shanxi Province, China during 1998~2001
CHI Wen-xue, WANG Jin-feng, LI Xin-hu, ZHENG Xiao-ying, LIAO Yi-lan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 921-925.
https://doi.org/10.1631/jzus.2007.A0921
Objective: To estimate the prevalence rates of neural tube defects (NTDs) in Heshun County, Shanxi Province, China by Bayesian smoothing technique. Methods: A total of 80 infants in the study area who were diagnosed with NTDs were analyzed. Two mapping techniques were then used. Firstly, the GIS software ArcGIS was used to map the crude prevalence rates. Secondly, the data were smoothed by the method of empirical Bayes estimation. Results: The classical statistical approach produced an extremely dishomogeneous map, while the Bayesian map was much smoother and more interpretable. The maps produced by the Bayesian technique indicate the tendency of villages in the southeastern region to produce higher prevalence or risk values. Conclusions: The Bayesian smoothing technique addresses the issue of heterogeneity in the population at risk and it is therefore recommended for use in explorative mapping of birth defects. This approach provides procedures to identify spatial health risk levels and assists in generating hypothesis that will be investigated in further detail.
|
|
Exploratory study of logistics service quality scale based on online shopping malls
FENG Yi-xiong, ZHENG Bing, TAN Jian-rong
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 926-931.
https://doi.org/10.1631/jzus.2007.A0926
Online shopping has already become the new mode that a lot of customers try to adopt. At the same time, the online shopping could not be successfully completed without logistics service. Logistics service quality (LSQ) has significant impact on revenue and profitability. This paper presents the issue from the perspective of the customer, and explores the initial factors of LSQ based on the online shopping through in-depth interview and the Delphi method. The survey uses a standard 7-point Likert-type scale to measure the LSQ. Empirical research results are shown in detail to confirm seven LSQ dimensions with Chinese characteristics, including timeliness quality, personal contact quality, order quality, order discrepancy handling, order condition and convenience. Statistical analyses of the investigation were conducted to test the reliability and validity of the LSQ evaluation model.
|
|
Optimal restructuring strategies under various dynamic factors
MENG Qing-xuan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 932-938.
https://doi.org/10.1631/jzus.2007.A0932
Corporate restructuring was identified as a new industrial force that has great impact on economic values and that therefore has become central in daily financial decision making. This article investigates the optimal restructuring strategies under different dynamic factors and their numerous impacts on firm value. The concept of quasi-leverage is introduced and valuation models are built for corporate debt and equity under imperfect market conditions. The model’s input variables include the quasi-leverage and other firm-specific parameters, the output variables include multiple corporate security values. The restructuring cost is formulated in the form of exponential function, which allows us to observe the sensitivity of the variation in security values. The unified model and its analytical solution developed in this research allow us to examine the continuous changes of security values by dynamically changing the coupon rates, riskless interest rate, bankruptcy cost, quasi-leverage, personal tax rate, corporate taxes rate, transaction cost, firm risk, etc., so that the solutions provide useful guidance for financing and restructuring decisions.
|
|
Congruences for finite triple harmonic sums
FU Xu-dan, ZHOU Xia, CAI Tian-xin
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 946-948.
https://doi.org/10.1631/jzus.2007.A0946
Zhao (2003a) first established a congruence for any odd prime p>3, S(1,1,1;p)≡−2Bp−3 (mod p), which holds when p=3 evidently. In this paper, we consider finite triple harmonic sum S(α,β,γ;p) (mod p) is considered for all positive integers α,β,γ. We refer to w=α+β+γ as the weight of the sum, and show that if w is even, S(α,β,γ;p)≡0 (mod p) for p≥w+3; if w is odd, S(α,β,γ;p)≡rBp−w (mod p) for p≥w, here r is an explicit rational number independent of p. A congruence of Catalan number is obtained as a special case.
|
|
On some projectively flat polynomial (α,β)-metrics
ZHAO Li-li
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 957-962.
https://doi.org/10.1631/jzus.2007.A0957
In this paper, we consider some polynomial (α,β)-metrics, and discuss the sufficient and necessary conditions for a Finsler metric in the form F=α+a1β+a2β2/α+a4β4/α3 to be projectively flat, where ai (i=1,2,4) are constants with a1≠0, α is a Riemannian metric and β is a 1-form. By analyzing the geodesic coefficients and the divisibility of certain polynomials, we obtain that there are only five projectively flat cases for metrics of this type. This gives a classification for such kind of Finsler metrics.
|
|
Projectively flat Asanov Finsler metric
HAN Jing-wei, YU Yao-yong
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 963-968.
https://doi.org/10.1631/jzus.2007.A0963
In this work, we study the Asanov Finsler metric F=α(β2/α2+gβ/α+1)1/2exp{(G/2)arctan[β/(hα)+G/2]}, where α=(αijyiyj)1/2 is a Riemannian metric and β=biyj is a 1-form, g∈(−2,2), h=(1−g2/4)1/2, G=g/h. We give the necessary and sufficient condition for Asanov metric to be locally projectively flat, i.e., α is projectively flat and β is parallel with respect to α. Moreover, we proved that the Douglas tensor of Asanov Finsler metric vanishes if and only if β is parallel with respect to α.
|
|
Comparison of two approximal proximal point algorithms for monotone variational inequalities
TAO Min
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(6): 969-977.
https://doi.org/10.1631/jzus.2007.A0969
Proximal point algorithms (PPA) are attractive methods for solving monotone variational inequalities (MVI). Since solving the sub-problem exactly in each iteration is costly or sometimes impossible, various approximate versions of PPA (APPA) are developed for practical applications. In this paper, we compare two APPA methods, both of which can be viewed as prediction-correction methods. The only difference is that they use different search directions in the correction-step. By extending the general forward-backward splitting methods, we obtain Algorithm I; in the same way, Algorithm II is proposed by spreading the general extra-gradient methods. Our analysis explains theoretically why Algorithm II usually outperforms Algorithm I. For computation practice, we consider a class of MVI with a special structure, and choose the extending Algorithm II to implement, which is inspired by the idea of Gauss-Seidel iteration method making full use of information about the latest iteration. And in particular, self-adaptive techniques are adopted to adjust relevant parameters for faster convergence. Finally, some numerical experiments are reported on the separated MVI. Numerical results showed that the extending Algorithm II is feasible and easy to implement with relatively low computation load.
|
21 articles
|