Performance Analysis of a DS-CDMA Cellular System with Effects of Soft Handoff in Log-Normal Shadowing Channels

Next generation wireless communication is based on a global system of fixed and wireless mobile services thatare transportable across different network back-bones,network service providers and network geographical boundaries.This paper presents an approach to investigate the effects of soft handover and perfect power control on the forward link ina DS-CDMA cellular system.Especially,the relationships between the size ofhandover zone and the capacity gain are e-valuated under the log-normal shadow channel.Then the optimization of maximum forward capacity is very necessary tobe done with the maximum size of soft handover zone to the various system characteristics.

基于Shadowing模型的无线入侵主机物理定位研究

为了在室内无线局域网环境中及时准确地定位非法入侵主机物理位置,以无线信号强度衰减过程的Shadowing传播模型为基础,研究了在一定的范围内如何合理地布置探测器,如何根据接收到的入侵主机的信号强度进行物理定位的问题.提出的定位方法可以有效地对抗入侵主机随机更改信号发射功率对定位精度的影响.实际测试结果表明,该方法定位误差平均约为2.3 m,可以满足室内环境下定位非法入侵主机的需求.

Log-normal湍流信道中超奈奎斯特传输系统的误码性能

超奈奎斯特传输理论与调制技术相结合,可有效提高系统的频谱效率。本文将超奈奎斯特理论引入大气激光通信系统,构建了一种适合于log-normal湍流信道的超奈奎斯特光传输系统,推导了QPSK调制方式下超奈奎斯特大气光传输系统平均误码率的表达式,利用蒙特卡洛仿真进一步分析了该系统的误码性能及频谱效率。结果表明:采用超奈奎斯特技术方案可以较大幅度提升大气光传输系统的频谱效率,当SNR为18 dB,S.I.为0.4时其频谱效率可以达到1.7 Baud/Hz,而未采用超奈奎斯特技术时只有1.56 Baud/Hz。另一方面,大气湍流对超奈奎斯特系统误码性能的影响较明显,当S.I.为0.4,BER为3.8×10^-3时,信噪比恶化了约1 dB。相对于频谱效率的提升,误码性能的恶化是能够接受的。因此,可以将FTN技术引入大气光传输系统来提高系统的频谱效率。

圆环上的逆shadowing映射(英文)

本文证明了圆环上shadowing性质和(Tc,Th-)逆shadowing性质的等价性.

Poisson Log-normal回归模型的影响评价(英文)

本文利用EM算法研究了来自于Lognormal分布权重的混合Poisson模型,即Poisson Lognormal回归模型,从而利用基于完全数据似然函数的条件期望进行影响评价.基于数据删除模型和局部影响分析方法,分别得到了广义Cook距离、Q距离和三种不同扰动模型下的正则曲率度量等诊断统计量.

变环境不同阶段下Log-normal分布缺失数据的可靠性估计

本文研究了变环境不同阶段Log-normal分布下,观测数据中包含缺失数据的情形下的可靠性估计问题。通过EM算法估计参数以及可靠性,最后通过模拟研究验证了本文方法的可行性。

一种估算三参数log-normal分布参数的近似方法

三参数（ｌｏｇ－ｎｏｒｍａｌ）分布在可靠性工程中有广泛应用，但其分布参数的估计较为困难。为解决这一问题，本文将极大似然法引入其概率图。

On the Relation of Shadowing and Expansivity in Nonautonomous Discrete Systems

In this paper we study shadowing property for sequences of mappings on compact metric spaces, i.e., nonautonomous discrete dynamical systems. We investi- gate the relations of various expansivity properties with shadowing and h-shadowing property.

Review of Shadow Detection and De-shadowing Methods in Remote Sensing

Shadow is one of the major problems in remotely sensed imagery which hampers the accuracy of information extraction and change detection.In these images,shadow is generally produced by different objects,namely,cloud,mountain and urban materials.The shadow correction process consists of two steps:detection and de-shadowing.This paper reviews a range of techniques for both steps,focusing on urban regions(urban shadows),mountainous areas(topographic shadow),cloud shadows and composite shadows.Several issues including the problems and the advantages of those algorithms are discussed.In recent years,thresholding and recovery techniques have become important for shadow detection and de-shadowing,respectively.Research on shadow correction is still an important topic,particularly for urban regions(in high spatial resolution data) and mountainous forest(in high and medium spatial resolution data).Moreover,new algorithms are needed for shadow correction,especially given the advent of new satellite images.

SHADOWING,EXPANSIVENESS AND SPECIFICATION FOR C^1-CONSERVATIVE SYSTEMS

We prove that a Cl-generic volume-preserving dynamical system （diffeomor- phism or flow） has the shadowing property or is expansive or has the weak specification property if and only if it is Anosov. Finally, as in [10, 27], we prove that the Cl-robustness, within the volume-preserving context, of the expansiveness property and the weak specifica- tion property, imply that the dynamical system （diffeomorphism or flow） is Anosov.

A new car-following model yielding log-normal type headways distributions

Modeling time headways between vehicles has attracted increasing interest in the traffic flow research field recently, because the corresponding statistics help to reveal the intrinsic interactions governing the vehicle dynamics. However, most previous micro-simulation models cannot yield the observed log-normal distributed headways. This paper designs a new car-following model inspired by the Galton board to reproduce the observed time-headway distributions as well as the complex traffic phenomena. The consistency between the empirical data and the simulation results indicates that this new car-following model provides a reasonable description of the car-following behaviours.

Inhomogeneous Shadowing Effect in High-Energy p-A Drell-Yan Process:

Having studied the initial state energy loss versus nuclear shadowing for the Drell-Yan dimuon pairproduction in the color string model,the inhomogeneous shadowing effect is considered in this paper.We find thatthe inhomogeneous shadowing effect does amend the rate of energy loss per unit path length,-dE/dz.Finally,thetheoretical results for the Drell-Yan differential cross-section ratios are compared with the E772 and E866 data.It isfound that the theoretical results are in good agreement with the experimental data.

Numerical study of hydraulic fracturing in the sectorial well-factory considering well interference and stress shadowing

In the Changqing Oilfield in northwest China, when traditional petroleum exploitation encounters forestry reserves or water source protection areas, sectorial well-factory design is proposed. The most distinct feature of a sectorial well-factory is the deviation of the well from the minimum horizontal principal stress, resulting in hydraulic fracture deflection after the initiation, along with possible well interference (i.e., fracture hit) and fracture coalescence in the oblique wells. Four indexes describing well deflection are then proposed according to fracture morphology. Several fracturing designs, including stage arrangement, fracturing sequences, and fracturing techniques are applied to study the feasibility of the sectorial well-factory design. The results show that the “gradual” or “sparse” stage arrangement, large injection rate, and simultaneous multifracture treatment can help to optimize the fracture morphology and stimulation design. However, the subsequent stress shadowing effect usually adversely affects the fracturing of adjacent wells. With a small initial horizontal stress difference, large injection rate and staggered stage arrangement can achieve ideal stimulation performance. Our results can provide a guidance for optimizing stimulation design in unconventional well-factory while taking into account environmental protection.

Precise Asymptotic Distribution of the Number of Isolated Nodes in Wireless Networks with Lognormal Shadowing

In this paper, we study the connectivity of multihop wireless networks under the log-normal shadowing model by investigating the precise distribution of the number of isolated nodes. Under such a realistic shadowing model, all previous known works on the distribution of the number of isolated nodes were obtained only based on simulation studies or by ignoring the important boundary effect to avoid the challenging technical analysis, and thus cannot be applied to any practical wireless networks. It is extremely challenging to take the complicated boundary effect into consideration under such a realistic model because the transmission area of each node is an irregular region other than a circular area. Assume that the wireless nodes are represented by a Poisson point process with densitynover a unit-area disk, and that the transmission power is properly chosen so that the expected node degree of the network equals lnn + ξ (n), where ξ (n) approaches to a constant ξ as n →?∞. Under such a shadowing model with the boundary effect taken into consideration, we proved that the total number of isolated nodes is asymptotically Poisson with mean e$ {-ξ}. The Brun’s sieve is utilized to derive the precise asymptotic distribution. Our results can be used as design guidelines for any practical multihop wireless network where both the shadowing and boundary effects must be taken into consideration.

Inverse Shadowing and Weak Inverse Shadowing Property

In this paper we show that an -stable diffeomorphism has the weak inverse shadowing property with respect to classes of continuous method and and some of the -stable diffeomorphisms have weak inverse shadowing property with respect to classes . In addition we study relation between minimality and weak inverse shadowing property with respect to class and relation between expansivity and inverse shadowing property with respect to class .

关于“shadowing exercise”方法在日语语法教学中的延伸应用研究

在教学过程中发现,很多学生无法摆脱母语迁移的负面影响。学习语法时,习惯将语法的语义高度概括并用汉语记忆,将例句的译文优先记忆,以辅助回忆日语原句。这导致很多学生的学习滞步不前。本文借鉴＂shadowing exercise＂方法,将其应用延伸至日语语法教学中,以期帮助学生摆脱母语迁移的负面影响。

Efficient Mean Estimation in Log-normal Linear Models with First-order Correlated Errors

In this paper, we propose a log-normal linear model whose errors are first-order correlated, and suggest a two-stage method for the efficient estimation of the conditional mean of the response variable at the original scale. We obtain two estimators which minimize the asymptotic mean squared error （MM） and the asymptotic bias （MB）, respectively. Both the estimators are very easy to implement, and simulation studies show that they are perform better.

A GENERALIZED LIPSCHITZ SHADOWING PROPERTY FOR FLOWS

In this paper,we define a generalized Lipschitz shadowing property for flows and prove that a flowΦgenerated by a C1vector field X on a closed Riemannian manifold M has this generalized Lipschitz shadowing property if and only if it is structurally stable.

Linear Maximum Likelihood Regression Analysis for Untransformed Log-Normally Distributed Data

Medical research data are often skewed and heteroscedastic. It has therefore become practice to log-transform data in regression analysis, in order to stabilize the variance. Regression analysis on log-transformed data estimates the relative effect, whereas it is often the absolute effect of a predictor that is of interest. We propose a maximum likelihood (ML)-based approach to estimate a linear regression model on log-normal, heteroscedastic data. The new method was evaluated with a large simulation study. Log-normal observations were generated according to the simulation models and parameters were estimated using the new ML method, ordinary least-squares regression (LS) and weighed least-squares regression (WLS). All three methods produced unbiased estimates of parameters and expected response, and ML and WLS yielded smaller standard errors than LS. The approximate normality of the Wald statistic, used for tests of the ML estimates, in most situations produced correct type I error risk. Only ML and WLS produced correct confidence intervals for the estimated expected value. ML had the highest power for tests regarding β1.

Suppression of Log-Normal Distributed Weather Clutter Observed by an S-Band Radar

We have observed weather clutter containing targets (ships) using an S-band radar with a frequency 3.05 GHz, a beam width 1.8°, and a pulsewidth 0.5 μs. To investigate the weather clutter amplitude statistics, we introduce the Akaike Information Criterion (AIC). We have found that the weather clutter amplitudes obey the log-normal, Weibull, and log-Weibull distributions with the shape parameters of 0.308 to 0.470, 4.42 to 4.51, and 15.91 to 16.44, respectively, for small data within the beam width of an antenna. We have proposed the log-normal/CFAR circuit modified a Cell-Averaging (CA) LOG/CFAR circuit. It is found that weather clutter is suppressed with improvement of 51.58 dB by log-normal/CFAR. As a result, we have showed that weather clutter observed by S-band radar does not obey the Rayleigh distribution and our log-normal/CFAR circuit has an effect on suppression of clutter and detection of target, while conventional LOG/CFAR circuit does not. In addition, if our circuit can be realized, we will have an advantage economically.