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Search Results: 1 - 10 of 63442 matches for " Guo Z "
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Piatetski-Shapiro Primes in a Beatty Sequence
Victor Z. Guo
Mathematics , 2015,
Abstract: Let $\alpha,\beta$ be real numbers such that $\alpha>1$ is irrational and of finite type, and let $c$ be a real number in the range $1
Comment on "Fastest learning in small-world neural networks"
Z. X. Guo
Computer Science , 2010,
Abstract: This comment reexamines Simard et al.'s work in [D. Simard, L. Nadeau, H. Kroger, Phys. Lett. A 336 (2005) 8-15]. We found that Simard et al. calculated mistakenly the local connectivity lengths Dlocal of networks. The right results of Dlocal are presented and the supervised learning performance of feedforward neural networks (FNNs) with different rewirings are re-investigated in this comment. This comment discredits Simard et al's work by two conclusions: 1) Rewiring connections of FNNs cannot generate networks with small-world connectivity; 2) For different training sets, there do not exist networks with a certain number of rewirings generating reduced learning errors than networks with other numbers of rewiring.
A Full Asymptotic Series of European Call Option Prices in the SABR Model with Beta = 1  [PDF]
Z. Guo, H. Schellhorn
Applied Mathematics (AM) , 2019, DOI: 10.4236/am.2019.106034
Abstract: We develop two new pricing formulae for European options. The purpose of these formulae is to better understand the impact of each term of the model, as well as improve the speed of the calculations. We consider the SABR model (with β=1) of stochastic volatility, which we analyze by tools from Malliavin Calculus. We follow the approach of Alòs et al. (2006) who showed that under stochastic volatility framework, the option prices can be written as the sum of the classic Hull-White (1987) term and a correction due to correlation. We derive the Hull-White term, by using the conditional density of the average volatility, and write it as a two-dimensional integral. For the correction part, we use two different approaches. Both approaches rely on the pairing of the exponential formula developed by Jin, Peng, and Schellhorn (2016) with analytical calculations. The first approach, which we call “Dyson series on the return’s idiosyncratic noise” yields a complete series expansion but necessitates the calculation of a 7-dimensional integral. Two of these dimensions come from the use of Yor’s (1992) formula for the joint density of a Brownian motion and the time-integral of geometric Brownian motion. The second approach, which we call “Dyson series on the common noise” necessitates the calculation of only a one-dimensional integral, but the formula is more complex. This research consisted of both analytical derivations and numerical calculations. The latter show that our formulae are in general more exact, yet more time-consuming to calculate, than the first order expansion of Hagan et al. (2002).
Strong summer monsoon during the cool MIS-13
Q. Z. Yin,Z. T. Guo
Climate of the Past (CP) & Discussions (CPD) , 2008,
Abstract: The δ18O record in deep-sea sediments show a significant reduced amplitude of the ice volume variations before Marine Isotope Stage 11, about 400 ka ago, with less warm interglacials and less cold glacials. The deuterium temperature and the greenhouse gases records in the Antarctic ice cores show the same feature. As the reduction in the amplitude of climate and greenhouse gases concentration variations before 400 ka BP is present in both deep-sea and ice cores, it is tempting to conclude that this is a worldwide phenomenon. This is not necessarily true, at least as far as some of the records, in particular of China and Europe, are concerned. The loess in northern China, the sedimentary core in the eastern Tibetan Plateau and the palaeosols in southern China all record an unusually warm and wet climate during Marine Isotope Stage 13, indicating an extremely strong East Asian summer monsoon. The pollen record from Europe shows that the climatic conditions during the interglacials previous to Marine Isotope Stage 11 are at least as warm as the younger interglacials. During Marine Isotope Stage 13, unusually strong African and Indian monsoon are recorded in the sediments of the equatorial Indian Ocean and of the Mediterranean Sea. Other extreme climate events are also recorded in sediment cores of the equatorial Atlantic, the Pacific, the subtropical South Atlantic Ocean and in the Lake Baikal of Siberia.
Strong summer monsoon during the cool MIS-13
Q. Z. Yin,Z. T. Guo
Climate of the Past Discussions , 2007,
Abstract: The δ18O record in deep-sea sediments show a significant reduced amplitude of the ice volume variations before Marine Isotope Stage 11, about 400 kyr ago, with less warm interglacials and less cold glacials. The deuterium temperature and the greenhouse gases records in the Antarctic ice cores show the same feature. As the reduction in the amplitude of climate and greenhouse gases concentration variations before 400 kyr BP is present in both deep-sea and ice cores, it is tempting to conclude that this is a worldwide phenomenon. This is not necessarily true, at least as far as some of the records, in particular of China, are concerned. The loess in northern China, the sedimentary core in the eastern Tibetan Plateau and the palaeosols in southern China all record an unusually warm and wet climate during Marine Isotope Stage 13, indicating an extremely strong East Asian summer monsoon. During the same interglacial, unusually strong African and Indian monsoon are recorded in the sediments of the equatorial Indian Ocean and of the Mediterranean Sea. Other extreme climate events are also recorded in sediment cores of the equatorial Atlantic, the Pacific, the subtropical South Atlantic Ocean and in the Lake Baikal of Siberia.
Performance Evaluation of Wavelet Packet Modulation over Mobile Satellite Channel
W. Z. Zhong,Q. Guo,Y. Guo
Information Technology Journal , 2009,
Abstract: The performance of WPM over the mobile satellite channel is presented and analyzed. The theory analysis and the simulation results show that the orthogonality of WPM can help the system be robust to the multipath effect and the extend period of WPM symbols can decrease the frequency selective fading of the system. The simulation result demonstrates that the performance of mobile satellite communication system using WPM is dependent on the support length of the wavelets, therefore a ratio decreasing algorithm is proposed in this study to improve the performance by weakening the support length effect. The simulation result shows that the better performance can be achieved by using proposed method.
Expert System Source Identification of Excessive Vibration
Kirk G. R.,Guo Z.
International Journal of Rotating Machinery , 2003,
Abstract:
An Adaptive Descriptor Design for Object Recognition in the Wild
Zhenyu Guo,Z. Jane Wang
Computer Science , 2013, DOI: 10.1109/ICCV.2013.319
Abstract: Digital images nowadays have various styles of appearance, in the aspects of color tones, contrast, vignetting, and etc. These 'picture styles' are directly related to the scene radiance, image pipeline of the camera, and post processing functions. Due to the complexity and nonlinearity of these causes, popular gradient-based image descriptors won't be invariant to different picture styles, which will decline the performance of object recognition. Given that images shared online or created by individual users are taken with a wide range of devices and may be processed by various post processing functions, to find a robust object recognition system is useful and challenging. In this paper, we present the first study on the influence of picture styles for object recognition, and propose an adaptive approach based on the kernel view of gradient descriptors and multiple kernel learning, without estimating or specifying the styles of images used in training and testing. We conduct experiments on Domain Adaptation data set and Oxford Flower data set. The experiments also include several variants of the flower data set by processing the images with popular photo effects. The results demonstrate that our proposed method improve from standard descriptors in all cases.
Detection of promoter hypermethylation of the CpG island of E-cadherin in gastric cardiac adenocarcinoma
W Guo, Z Dong, Y Guo, G Kuang, Z Yang, Z Chen
European Journal of Medical Research , 2009, DOI: 10.1186/2047-783x-14-10-453
Abstract: A nested MSP approach, immunohistochemistry method and RT-PCR were used respectively to examine the methylation status of the 5' CpG island of E-cadherin, its protein expression and mRNA expression in tumors and corresponding normal tissues.E-cadherin was methylated in 63 of 92 (68.5%) tumor specimens, which was significantly higher than that in corresponding normal tissues (P < 0.001). Methylation frequencies of stage III and IV tumor tissues was significantly higher than that in stage I and II tumor tissues (P = 0.01). Methylation status of poor differentiation group was significantly higher than moderate and poor-moderate differentiation groups (P < 0.01). By immunostaining 51 of 92 tumor tisssues demonstrated heterogeneous, positive immunostaining of tumor tissues (44.6%), significantly different from matched normal tissues (P < 0.001). Positive immunostaining of stage III and IV tumor tissues was significantly lower than stage I and II tumor tissues (P < 0.01). Poor differentiation group was also significantly lower than moderate and poor-moderate differentiation groups (P < 0.05). 80 percent of tumor tissues with E-cadherin gene methylated showed inactivated mRNA expression.High methylation status of the 5' CpG island of E-cadherin gene may be one of the mechanisms in the development of gastric cardiac adenocarcinoma.E-cadherin is a Mr 120,000 transmembrane glycoprotein expressed on epithelial cells and is responsible for homophilic, Ca2+-dependent intercellular adhesion that is essential for the maintenance of normal tissue architecture in epithelial tissues [1]. The cytoplasmic domain of E-cadherin binds to α-, β-, and γ-catenins, which are in turn linked to actins, and this interaction is critical for its function [2]. Cell-cell and cell-matrix interactions are crucially involved in neoplastic transformation and metastasis [3,4]. Defective cell adhesion may contribute to loss of contact inhibition of growth and loss of cell adhesion may account for the abil
Strong asymmetry of hemispheric climates during MIS-13 inferred from correlating China loess and Antarctica ice records
Z. T. Guo, A. Berger, Q. Z. Yin,L. Qin
Climate of the Past (CP) & Discussions (CPD) , 2009,
Abstract: We correlate the China loess and Antarctica ice records to address the inter-hemispheric climate link over the past 800 ka. The results show a broad coupling between Asian and Antarctic climates at the glacial-interglacial scale. However, a number of decoupled aspects are revealed, among which marine isotope stage (MIS) 13 exhibits a strong anomaly compared with the other interglacials. It is characterized by unusually positive benthic oxygen (δ18O) and carbon isotope (δ13C) values in the world oceans, cooler Antarctic temperature, lower summer sea surface temperature in the South Atlantic, lower CO2 and CH4 concentrations, but by extremely strong Asian, Indian and African summer monsoons, weakest Asian winter monsoon, and lowest Asian dust and iron fluxes. Pervasive warm conditions were also evidenced by the records from northern high-latitude regions. These consistently indicate a warmer Northern Hemisphere and a cooler Southern Hemisphere, and hence a strong asymmetry of hemispheric climates during MIS-13. Similar anomalies of lesser extents also occurred during MIS-11 and MIS-5e. Thus, MIS-13 provides a case that the Northern Hemisphere experienced a substantial warming under relatively low concentrations of greenhouse gases. It suggests that the global climate system possesses a natural variability that is not predictable from the simple response of northern summer insolation and atmospheric CO2 changes. During MIS-13, both hemispheres responded in different ways leading to anomalous continental, marine and atmospheric conditions at the global scale. The correlations also suggest that the marine δ18O record is not always a reliable indicator of the northern ice-volume changes, and that the asymmetry of hemispheric climates is one of the prominent factors controlling the strength of Asian, Indian and African monsoon circulations, most likely through modulating the position of the inter-tropical convergence zone (ITCZ) and land-sea thermal contrasts.
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