Unambiguous Acquisition and Tracking Technique for General BOC Signals

This article presents a new unambiguous acquisition and tracking technique for general Binary Offset Carrier (BOC) ranging signals, which will be used in modern GPS, European Galileo system and Chinese BeiDou system. The test criterion employed in this technique is based on a synthesized correlation function which completely removes positive side peaks while keeping the sharp main peak. Simulation results indicate that the proposed technique completely removes the ambiguity threat in the acquisition process while maintaining relatively higher acquisition performance for low order BOC signals. The potential false lock points in the tracking phase for any order BOC signals are avoided by using the proposed method. Impacts of thermal noise and multipath on the proposed technique are investigated; the simulation results show that the new method allows the removal of false lock points with slightly degraded tracking performance. In addition, this method is convenient to implement via logic circuits

Modification of nucleon properties in nuclear matter and finite nuclei

We present a model for the description of nuclear matter and finite nuclei, and at the same time, for the study of medium modifications of nucleon properties. The nucleons are described as nontopological solitons which interact through the self-consistent exchange of scalar and vector mesons. The model explicitly incorporates quark degrees of freedom into nuclear many-body systems and provides satisfactory results on the nuclear properties. The present model predicts a significant increase of the nucleon radius at normal nuclear matter density. It is very interesting to see the nucleon properties change from the nuclear surface to the nuclear interior.Comment: 22 pages, 10 figure

Some analysis on mobile-agent based network routing

©2004 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Deployment of mobile agents in network-based applications has attracted lots of attentions in recent years. How to control the activities of agents is crucial for effective application of mobile agents. This paper focuses on the application of mobile agents in network routing. Two important activity properties of mobile agents are identified: the probability of success (the probability of finding the destination) and the distribution of mobile agents running in the network. To our knowledge, little work has been done on these two aspects. Our results show that the number of mobile agents can be controlled by adjusting the number of agents generated per request and the number of jumps each mobile agent can move. Thus, we can improve network performance by tuning relevant parameters.Wenyu Qu, Hong She

NIMBUS-5 sounder data processing system. Part 2: Results

The Nimbus-5 spacecraft carries infrared and microwave radiometers for sensing the temperature distribution of the atmosphere. Methods developed for obtaining temperature profiles from the combined set of infrared and microwave radiation measurements are described. Algorithms used to determine (a) vertical temperature and water vapor profiles, (b) cloud height, fractional coverage, and liquid water content, (c) surface temperature, and (d) total outgoing longwave radiation flux are described. Various meteorological results obtained from the application of the Nimbus-5 sounding data processing system during 1973 and 1974 are presented

A Novel FastICA Method for the Reference-based Contrast Functions

This paper deals with the efficient optimization problem of Cumulant-based contrast criteria in the Blind Source Separation (BSS) framework, in which sources are retrieved by maximizing the Kurtosis contrast function. Combined with the recently proposed reference-based contrast schemes, a new fast fixed-point (FastICA) algorithm is proposed for the case of linear and instantaneous mixture. Due to its quadratic dependence on the number of searched parameters, the main advantage of this new method consists in the significant decrement of computational speed, which is particularly striking with large number of samples. The method is essentially similar to the classical algorithm based on the Kurtosis contrast function, but differs in the fact that the reference-based idea is utilized. The validity of this new method was demonstrated by simulations

Analysis of the Fusion Hindrance in Mass-symmetric Heavy Ion Reactions

The fusion hindrance, which is also denominated by the term extra-push, is studied on mass-symmetric systems by the use of the liquid drop model with the two-center parameterization. Following the idea that the fusion hindrance exists only if the liquid drop barrier (saddle point) is located at the inner side of the contact point after overcoming the outer Coulomb barrier, the reactions in which two barriers are overlapped with each other are determined. It is shown that there are many systems where the fusion hindrance does not exist for the atomic number of projectile or target nucleus $Z\leq43$, while for $Z>43$, all of the mass-symmetric reactions are fusion-hindered.Comment: 6 pages, 4 figures. to be published in Sci. in China