影响PDC钻头在定向井中性能的原因分析

本文系统地研究了PDC钻头结构的设计理论及其特点,分析了影响PDC钻头在定向井中性能的因素,包括PDC钻头漂移的因素分析,地层各向异性对钻头定向性能影响等。用经验公式描述了PDC钻头的导向能力和漂移趋势,依据导向能力对IADC钻头剖面标准进行重新分类,并着重分析了保径特征参数对PDC钻头定向性能的影响。     

论平面设计中的纯粹性

平面设计中的纯粹性是一种深厚的审美境界.纯粹的境界是真诚和自然,它像一只无形的手随时指导着平面设计的创作过程.作为平面设计的一种语言特点,纯粹具有扣人心弦的艺术效果.     

Impacts,sustainability, and resilience on the Egyptian tourism and hospitality industry after the Russian airplane crash in 2015

The Russian airplane crash in 2015 has severely affected the tourism industry in Egypt. The present article is focused on the impacts of economic, political, and social impacts on Egyptian tourism after this crisis. The present study aimed at dealing with the crisis to mitigate the consequences and allow the companies to make the best use of it to restore their business. The present article has also discussed the crisis impacts on the financial situation of company A which is one of the top five hospitality companies in Egypt. Crisis management and investments in human resources were the most effective strategies to overcome the harsh consequences of the crisis on tourism sector. The present study data is based on the Egyptian ministry of tourism figures, internet, articles, and international channels reports aimed to explain how the political, social, and economic events had a negative impact on the hotel industry in Egypt.     

一种低复杂度的多元LDPC译码算法

针对多元低密度奇偶校验（LDPC）码译码复杂度高、时延大等问题，提出了一种基于硬信息的低复杂度多元LDPC译码算法。来自信道的接收信号在初始化时，先进行非均匀量化预处理。在迭代过程中，校验节点端只需传输单个比特的二进制硬可靠度信息至变量节点。在变量节点端，可靠度信息按比特位进行简单的累加和更新，无需任何的系数修正操作。同时，变量节点使用了全信息的方式将信息传输至与其相邻的校验节点。仿真结果显示，与基于比特可靠度（BRB）的多元LDPC译码算法相比，提出的算法在较低量化比特情况下，能获得约0.3 dB的译码性能增益，且译码复杂度更低。