一种“北斗”B1C信号无模糊捕获算法

针对“北斗”B1C信号同步过程中存在的捕获模糊性问题,根据“北斗”B1C信号的信号特点,基于伪相关函数方法,设计了一种适用于“北斗”B1C信号的无模糊捕获算法。该算法采用数据分量和导频分量非相干组合的捕获策略,实现了B1C信号数据分量和导频分量的无模糊捕获,提高了捕获灵敏度。利用导航终端接收的卫星信号数据,对所提捕获算法进行了仿真验证,并分析了其无模糊捕获性能和捕获灵敏度。仿真结果表明,所提算法能准确且快速地捕获“北斗”B1C信号。     

Whether low-cost-carrier passengers spend more on duty-free goods at the airport? Evidence from Incheon International Airport

With a dramatic growth in the low-cost carrier (LCC) traffic around the world, many airports have built budget terminals to accommodate the LCC flights with cheaper airport charge to the airlines but inferior shopping environment and service quality to the passengers. This study aims to answer the following research questions: i). Whether the LCC passengers have higher purchasing power than FSC (full-service carrier) passengers for the airport concessions, particularly the duty-free goods? ii). Would the budget terminal design contribute to or jeopardize the LCC passengers' airport concession expenditure? iii). How could the airport operator maximize its concession revenue by re-designing terminal or re-allocating flight slots? We collect the actual airport duty-free transaction data from Incheon International Airport (ICN) for an empirical investigation. Our empirical evidence first suggests that LCC passengers could have comparable or even higher purchasing power than FSC passengers in consuming duty-free goods at the airport. Among all the LCC passengers, Chinese have the highest purchasing power. Second, the inferior shopping environment and service quality of budget terminal seriously jeopardize the duty-free sales from the LCC passengers. Third, counterfactual analyses show that, if ICN could convert its budget terminal into a conventional terminal, 44 million USD more duty-free sales can be generated per year. Even keeping the current terminal design, re-allocating the LCC flights between the budget terminal and conventional terminal could bring approximately 4.9 million USD more duty-free sales per year. The findings provide managerial implications to ICN and other airports for effective airport revenue management. First, the budget terminal design may not be ideal to accommodate LCC traffic as it damages the concession revenue from particular LCC passengers with high purchasing power. Second, exploring the concession revenue from the growing LCC traffic could help maintain an airport's advantage in aeronautical charge under single-till regulation.     

An airline's management strategies in a competitive air transport market

Over the last decade, the demand for domestic and international flights in Korea has increased substantially. To meet the strong flight demands, several low cost carriers have begun to offer flight services. In addition, full service carriers have been motivated to establish their own subsidiary low cost carriers to maintain their market share against rival low cost carriers. This paper studies the management strategies of three kinds of airlines - full service carrier, its subsidiary low cost carrier and rival low cost carrier - based on game theory in the competitive air transport market. Each airline is assumed to act as a player and chooses strategies regarding airfare, flight frequency, and the number of operating aircrafts for specific routes while maximizing its own profits. Demand leakages between the airlines are considered in the flight demand function according to the selected strategies of all airlines. Through various game situations reflecting realistic features, this study provides managerial insights that can be applied in the competitive air transport market.     

一种用于卫星通信的自适应编码调制信号接收方法

针对常规接收方法接收自适应编码调制信号时存在的接收过程易中断、数据不连续等问题,提出了一种适用于卫星信道的自适应编码调制信号接收方法。该方法通过采用统一的解调结构实现对不同调制信号的连续跟踪;利用接收端保存的帧同步字调制波形副本与接收信号中的帧同步字波形的相关结果,对解调方式切换时载波相位跳变值进行估计和补偿,解决了帧同步的连续跟踪问题。与现有方法相比,该方法不需要导频信号,可节省系统开销。     

政府补贴与国际贸易动态优势分析

本文运用国际贸易新理论分析了显性补贴促成动态比较优势的效果．主张我国扶持具有外部经济效应的高新科技产业以培养动态比较优势，其重要的扶持措施就是实行政府补贴(包括显性补贴与隐性补贴)，并对加强政府隐性补贴提出了建议。’     

传统重负的承载者与叛逆者——中国现代文学中长子形象探析

在中国现代文学作品中,许多作品塑造了长子惊人相似的性格特征:卑柔软弱、双重人格、自我牺牲。但在新思想的冲击与内心潜在力量的合力下,他们的人性复苏了,裂变出了反抗的因子,成了旧家庭的叛逆者。     

一种基于改进FFT的MPSK载波估计方法

针对多进制相移链控(MPSK)信号相干解调中载波同步问题,提出一种基于Zoom FFT及频域内插的方法进行载波提取。该方法通过信号的非线性变换,在时频域内实现载波频率的粗估计,在此基础上通过频域内的插值校正实现载波的准确提取。仿真试验结果表明,本算法提取的载波具有较高的准确性,估计的最大相对误差只有10-6量级。该方法不需要特定图案的前导字,结构简单,可估计的载波频率适应范围大,在高信噪比的情况下硬件实现系统实时性好。     

Do owner–operators pose a safety risk on the nation’s highways?

Despite persistent claims in the motor carrier industry of poorer safety performance of owner–operators, there is little empirical work directly comparing owner–operator safety performance to that of employee drivers. This study assesses the statistical significance of differences in the safety performance between owner–operators and employee drivers. This study also expands on previous driver focused safety models by examining how driver and carrier characteristics affect safety performance. Data for this study were derived from the Motor Carrier Management Information System (MCMIS), and the Commercial Driver’s License Information System (CDLIS) databases. Study results provide evidence that owner–operators are associated with more driver- and vehicle-out-of-service violations but experience lower crash rates than do employee drivers.     

英语教学中隐性言语和体态语使用探索

隐性言语和体态语的正确使用,对教学十分重要,它能帮助沟通师生心灵,融洽师生关系.本文论述了隐性言语和体态语在英语教学中的独特作用.     

一种高速多模式载波同步方法

针对载波同步的两个关键问题———提高速度和适应多模式,研究了锁相环的鉴频辅助方法,构建了基于Costas鉴相和点积、差积鉴频算法的环路。仿真结果表明,所研究的载波同步方法适应BPSK、QPSK和8PSK等调制方式,同步速度约为传统方法的2倍。