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Search Results: 1 - 10 of 65524 matches for " Ning Yang "
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Cross-wired lamplighter groups and linearity of automata groups
Ning Yang
Mathematics , 2015,
Abstract: We consider the two generalizations of lamplighter groups: automata groups generated by Cayley machine and cross-wired lamplighter groups. For a finite step two nilpotent group with central squares, we study its associated Cayley machine and give a presentation of the corresponding automata group. We show the automata group is a cross-wired lamplighter group and does not embed in the wreath product of a finite group with a torsion free group. For a subfamily of such finite step two nilpotent groups, we prove that their associated automata groups are linear.
A Digital Background Calibration Technique for Successive Approximation Register Analog-to-Digital Converter  [PDF]
Ling Du, Ning Ning, Shuangyi Wu, Qi Yu, Yang Liu
Journal of Computer and Communications (JCC) , 2013, DOI: 10.4236/jcc.2013.16006

A digital background calibration technique that corrects the capacitor mismatches error is proposed for successive approximation register analog-to-digital converter (SAR ADC). The technique is implemented in SAR ADC which is based on tri-level switching. The termination capacitor in the Digital-to-Analog Converter (DAC) is regarded as a reference capacitor and the digital weights of all other unit capacitors are corrected with respect to the reference capacitor. To make a comparison between the size of the unit capacitor and that of the reference capacitor, each input sample is quantized twice. The unit capacitor being calibrated is swapped with the reference capacitor during the second conversion. The difference between the two conversion results is used to correct the digital weight of the unit capacitor under calibration. The calibration technique with two reference capacitors is presented to reduce the number of parameters to be estimated. Behavior simulation is performed to verify the proposed calibration technique by using a 12-bit SAR ADC with 3% random capacitor mismatch. The simulation results show that the Signal-to-Noise and Distortion Ratio (SNDR) is improved from 57.2 dB to 72.2 dB and the Spurious Free Dynamic Range (SFDR) is improved from 60.0 dB to 85.4 dB.

An Incremental-Selective Cooperative Relaying Scheme with Best Relay Selection in WSN80002  [PDF]
Shaoqing Wang, Hanlin Yang, Ning Zhou, An Wang
Journal of Computer and Communications (JCC) , 2015, DOI: 10.4236/jcc.2015.33018

In wireless sensor networks, the traditional multi-relay incremental cooperative relaying (MIR) scheme could improve the system throughput over the fading channel enormously by exploiting multiple relay nodes to retransmit the copy of the source packet to the destination in turn, but increase the energy consumption and transmission delay. In order to mitigating the energy consumption and transmission delay, this paper proposes a new cooperative relaying scheme termed as incremental-selective relaying with best-relay selection (ISR), which selects the best relay node from the candidate relays to retransmit the packet to the destination only when the direct transmission between the source and the destination is not successful. Expressions of normalized throughput, normalized delay and energy efficiency for the ISR and MIR systems are derived respectively and their performances are compared through simulations. The results show that normalized throughput, normalized delay and energy efficiency for the ISR system all outperform the corresponding performances of the MIR system. Especially, there are different the optimal number of relays which can maximize the energy efficiency of system.

FDK Half-Scan with a Heuristic Weighting Scheme on a Flat Panel Detector-Based Cone Beam CT (FDKHSCW)
Dong Yang,Ruola Ning
International Journal of Biomedical Imaging , 2006, DOI: 10.1155/ijbi/2006/83983
Abstract: A cone beam circular half-scan scheme is becoming an attractive imaging method in cone beam CT since it improves the temporal resolution. Traditionally, the redundant data in the circular half-scan range is weighted by a central scanning plane-dependent weighting function; FDK algorithm is then applied on the weighted projection data for reconstruction. However, this scheme still suffers the attenuation coefficient drop inherited with FDK when the cone angle becomes large. A new heuristic cone beam geometry-dependent weighting scheme is proposed based on the idea that there exists less redundancy for the projection data away from the central scanning plane. The performance of FDKHSCW scheme is evaluated by comparing it to the FDK full-scan (FDKFS) scheme and the traditional FDK half-scan scheme with Parker's fan beam weighting function (FDKHSFW). Computer simulation is employed and conducted on a 3D Shepp-Logan phantom. The result illustrates a correction of FDKHSCW to the attenuation coefficient drop in the off-scanning plane associated with FDKFS and FDKHSFW while maintaining the same spatial resolution.
An Effective Vaccine Strategy of Translating Apoptotic Tumor Cells into Cancer Vaccine
Ning Yang,Anjun Liu
Cancer and Clinical Oncology , 2012, DOI: 10.5539/cco.v1n1p167
Abstract: Cancer vaccine has been regarded as the most attractive treatment for the patients. Our previous work showed that cartilage polysaccharide of short-chain (CPS) could induce apoptosis of L1210 cell lines through mitochondria apoptosis pathway and mice treated with CPS didn’t develop tumors after L1210 cell inoculation when compared to control mice without treatment. In present work, we developed a vaccine based on previous experiments and results showed that four in ten mice vaccinated didn’t show proliferation of ascite tumors while the mice in the control group didn’t show inhibition of tumor growth. We further identified the antibody with immunoflourescence and western blot from the serum of immunized mice which can recognize a protein with molecular weight of 35 kDa. Finally, we used mass spectrometry and identified the target recognized by the antiserum annexin A2, which is involved in cell proliferation, differentiation and apoptosis processes and is tightly associated with cancer progression and chemoresistance.
Non-uniform Spatial Distribution of Spin Polarization in Topological Insulator (Bi2Te3) Surface
Ning Wang,Z. Yang
Physics , 2014,
Abstract: We found, through extensive study of micro reflectance difference spectroscopy images of Bi2Te3 topological insulator surface, the first clear experimental evidence that there is non-uniform spatial distribution of spin polarization (spin domains) in the surface of the topological insulator. These spin domains involve when they are at different temperatures, in an external magnetic field, and can be driven by electric current. Such surface spin domains in topological insulators have never been predicted by any theory so far.
Dynamics of a two-level system under the simultaneous influence of a spin bath and a boson bath
Ning Wu,Yang Zhao
Physics , 2013, DOI: 10.1063/1.4817336
Abstract: We study dynamics of a two-level system coupled simultaneously to a pair of dissimilar reservoirs, namely, a spin bath and a boson bath, which are connected via finite interbath coupling. It is found that the steady-state energy transfer in the two-level system increases with its coupling to the spin bath while optimal transfer occurs at intermediate coupling in the transient process. If the two-level system is strongly coupled to the spin bath, the population transfer is unidirectional barring minor population oscillations of minute amplitudes. If the spin bath is viewed as an atomic ensemble, robust generation of macroscopic superposition states exists against parameter variations of the two-level system and the boson bath.
A General Theory of Hypothesis Tests and Confidence Regions for Sparse High Dimensional Models
Yang Ning,Han Liu
Statistics , 2014,
Abstract: We consider the problem of uncertainty assessment for low dimensional components in high dimensional models. Specifically, we propose a decorrelated score function to handle the impact of high dimensional nuisance parameters. We consider both hypothesis tests and confidence regions for generic penalized M-estimators. Unlike most existing inferential methods which are tailored for individual models, our approach provides a general framework for high dimensional inference and is applicable to a wide range of applications. From the testing perspective, we develop general theorems to characterize the limiting distributions of the decorrelated score test statistic under both null hypothesis and local alternatives. These results provide asymptotic guarantees on the type I errors and local powers of the proposed test. Furthermore, we show that the decorrelated score function can be used to construct point and confidence region estimators that are semiparametrically efficient. We also generalize this framework to broaden its applications. First, we extend it to handle high dimensional null hypothesis, where the number of parameters of interest can increase exponentially fast with the sample size. Second, we establish the theory for model misspecification. Third, we go beyond the likelihood framework, by introducing the generalized score test based on general loss functions. Thorough numerical studies are conducted to back up the developed theoretical results.
A Timing Skew Calibration Scheme in Time-Interleaved ADC  [PDF]
Jing Li, Yang Liu, Hao Liu, Shuangyi Wu, Ning Ning, Qi Yu
Journal of Computer and Communications (JCC) , 2013, DOI: 10.4236/jcc.2013.16007

This paper proposes a digital background calibration scheme for timing skew in time-interleaved analog-to-digital converters (TIADCs). It detects the relevant timing error by subtracting the output difference with the sum of the first derivative of the digital output. The least-mean-square (LMS) loop is exploited to compensate the timing skew. Since the calibration scheme depends on the digital output, all timing skew sources can be calibrated and the main ADC is maintained. The proposed scheme is effective within the entire frequency range of 0 ? fs/2. Compared with traditional calibration schemes, the proposed approach is more feasible and consumes significantly lesser power and smaller area.

An image analysis method for quantification of hepatic perfusion based on contrast-enhanced ultrasound imaging  [PDF]
Yi-xin Li, Fang Yang, Ning Gu
Journal of Biomedical Science and Engineering (JBiSE) , 2008, DOI: 10.4236/jbise.2008.12019
Abstract: Information about hepatic perfusion is used in clinical liver disease diagnosis. An image analy-sis system can help physicians make efficient and accurate diagnosis. The objective of this study is to propose an image analysis method for the quantification of the hepatic perfusion based on contrast-enhanced ultrasound imaging (CEUI). The proposed method contains frame selection, image registration, digital subtraction and grey-scale calculation. Then, by processing an image sequence, a time-intensity curve (TIC) for hepatic perfusion is derived. The kernel of this image analysis technology is digital subtrac-tion and its accuracy is improved by frame selec-tion and image registration. The advantage of this method is that it can obtain the perfusion information of the whole liver which is rarely ob-tained by traditional image analysis technology; therefore, it is a supplement of the traditional image analysis method. This method is applied on the quantification of a rabbit’s hepatic perfu-sion and the result shows the efficiency of it.
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