Prices, Delay, and the Dynamics of Trade

We characterize the dynamics of trading patterns and market composition when trade is bilateral, finding a trading partner is costly, prices are determined by bargaining, and preferences are private information. We show that equilibrium is inefficient and exhibits delay as sellers price discriminate between buyers with different values. As frictions vanish, transaction prices are asymptotically competitive and the welfare loss of inefficient trading approaches zero, even though the trading patterns continue to be inefficient and delay persists. Journal of Economic Literature Classification Numbers: D40, D50.     

时延测量方法的分析与比较

介绍了5种测量时延的先进方法。通过对这些方法的深入分析和大量实验，得出了这些方法的最佳测量不确定度。同时还提出了“时延传递标准”的新方案，该方案的测量不确定度可达0．01—0．02ns。     

WCDMA 移动终端用RAKE接收机结构与实现

针对WCDMAFDD下行链路,提出了一种接收机结构。与传统接收机不同,该结构是根据多径来拉动(延时)输入信号,即根据多径把各径的信号延时对齐,而本地码的相位只需一个,来对多径支路解扩,并直接合并输出。该结构可进一步通过串行方法实现,大大减少硬件资源。由于采用全硬件技术,因此,便于ASIC集成。     

中国——东盟自由贸易区降税效应分析

中国——东盟自由贸易区自启动以来,双方的经贸关系一路“绿灯”,迅速进入“黄金发展时期”,2004年双边贸易额实现了历史性的跨越。本文重点分析“早期收获”方案和《货物贸易协议》降税安排实施后,双方产生的贸易创造效应,以及在开放贸易环境下,从货物贸易角度来分析的转移或获得的有形商品的价值增值。     

面向成本优化的航班延误损失差异研究

航班延误给旅客出行造成不便也增加了航空公司的运营成本。在航班地面等待过程中,维持机舱供电的成本是延误损失的重要组成部分。通过考虑不同供电方式完善了航班延误成本模型,提出了客舱等待容忍时限概念,深入分析了使用廊桥静变电源和APU（飞机辅助发动机）供电时,航班总地面延误成本随时间的变化趋势。在对航班延误成本量化分析的同时,讨论了在客舱内实施地面延误的极限时间。以B737-800、A320和B747-200三种主流机型为例,采用本文模型对延误成本、延误损失比例、客舱等待容忍时间进行计算机仿真模拟,结果表明,本文模型能量化分析航班地面延误成本,能反映廊桥静变电源供电的经济优势,能为航空公司优化运营成本提供可靠工具。     

一种单信道时频重叠信号调制识别方法

针对单信道时频重叠信号调制方式的识别分类问题,提出了基于信号相关特性的调制识别方法。在研究所选数字通信信号的相关特性的基础上,提取信号延迟相关和瞬时自相关谱峰的数量、幅度和位置方差作为特征参数,实现了同载频时频重叠双信号的调制识别。仿真结果表明,在理想高斯白噪声背景下,该方法具有良好的识别性能,当信噪比大于-5 dB时,其正确识别率达到95%以上。     

LS曲线拟合下的时差估计

针对时差估计（TDE）易受噪声影响产生模糊的问题,推导了单频信号、线性调频（LFM）信号以及二进制相移键控（BPSK）信号的互相关（CC）函数表达式,以最小二乘（LS）曲线拟合细化CC函数的幅度谱,获取精确的时差估计。首先对CC函数的幅度谱进行谱峰搜索,得到时差的粗估计,然后对CC函数的幅度谱以时差的粗估计为界,根据脉内调制类型,选择相应的一次或二次曲线,进行LS曲线拟合,降低噪声项对信号项的影响,可有效排除伪峰和局部最大,获得时差的精确估计。仿真结果显示,在信噪比大于6 dB时,BPSK信号的时差估计均方根误差接近零。     

Inventory ordering policies of delayed deteriorating items under permissible delay in payments

The existing literature on inventory of deteriorating items considers deterioration to begin as soon as the items are stocked. However, there are several deteriorating items that do not start deteriorating immediately they are held in stock. Some farm produce like potatoes, yams and even some fruits and vegetables have this property. Depletion of these items as soon as they are stocked will depend on demand, and when deterioration begins, it will depend on both demand and deterioration. In this paper, we develop a mathematical model on the inventory of deteriorating items that do not start deteriorating immediately they are stocked. The model also takes into cognizance the fact that in business activities nowadays customers are given some allowed period within which to settle for the goods supplied to them. They can use the accrued money from sales of the supplied goods to earn interest within the allowed period. They are charged interest only when they fail to settle the amount they owe the supplier at the end of the allowed period.     

The Economic Impact of Capital Expenditures: Environmental Regulatory Delay as a Source of Competitive Advantage?

This study tests the proposal that by undertaking voluntary capital expenditures that are subject to lengthy environmental regulatory delays, listed companies can gain a competitive advantage. The stock market is found to react positively to new capital expenditure announcements when projects are expected to experience long delays in obtaining environmental regulatory approval. Two sources of potential competitive advantage are firm learning and first mover advantages. Lengthy delays in regulatory processes and high compliance costs incurred for environmentally‐sensitive projects may allow firms opportunities to develop specialised capabilities and/or to deter industry competitors and new entrants, resulting in greater expected project NPVs. The findings also underscore the importance of non‐financial environmental information to investors in their assessment of firm value.     

一种通信卫星在轨测试中群时延特性测量方法及工程实现

讨论了群时延的概念及群时延的测试原理和方法,并在通信卫星在轨测试的工程实现中,针对卫星转发器频段多及Ka频段转发器频率较高的特点,重点描述了综合群时延测试的方案设计及实现。经工程验证,该方法提高了在轨测试的效率和群时延测试精度。