辽河减压渣油中金属铁的赋存与分布特征

考察了辽河减渣在吸附分离、酸性溶液萃取和沥青质轻度降解过程中金属铁的分布和转移情况。结果表明，辽河减渣中有近90％的铁富集在胶质和沥青质中，部分铁以侧链较短的环烷酸盐或酚盐形式存在，部分铁连接在沥青质分子的侧链上，或是被包裹在沥青质大分子中。     

硫铁矿沸腾炉内蒸发管组防磨技术的探讨

为减少磨损,沸腾炉内蒸发管采用加焊半圆形钢板防磨.探讨了沸腾炉内蒸发管加焊半圆形钢板的防磨机理.实际使用情况表明,加焊半圆形钢板防磨大大降低了维修费用,显著提高了防磨效果.     

井下伴热电缆导体集肤效应的有限元法分析

运用有限元法, 对交频井下伴热电缆导体内部的集肤效应现象进行了数值模拟和分析,比较直观地得出交频电缆中电流密度的分布特性, 以及交流电的不同频率对导体集肤深度的影响。在集肤效应作用下, 电缆导体内部的有效过流面积减小, 交流阻抗显著加大, 其发热量也很大,井下电缆伴热加热技术就是利用这一原理来加热原油的。通过数值模拟, 可以定量地说明电参数对加热效果的影响, 为稠油井井下电缆伴热技术中优化加热参数提供指导。     

New Environment-Friendly Approach for Bastnasite Metallurgic Treatment (I): Extraction of Tetravalent Cerium from Sulphuric Acid Medium with Di(2-ethylhexyl) Phosphoric Acid

Bastnasiteisamainsourceofrareearthproducts inwhichCeO2/REOisabout50%.Atpresent,a cidity leachingcombinedwithalkali conversion method[1]iscommonlyusedinthebastnasitetreat ment.Thismethodisunfriendlytotheenvironment becausetheradioactiveelementofthoriuman…     

给水铜管分水布置的支管缩径可行性分析

住宅给水铜管分水布置是一种技术可行、经济合理的管道布置方式。在确定了管道的设计要求后,分析了分水缩径后的流速情况,明确了分水布置方式中支管缩径的技术状况。分析表明,支管缩径是可行的。     

企业施工定额的编制以及施工成本分析平台的应用

本文阐述了施工企业内部编制定额的必要性和成本分析平台的实用性,并根据多年的工作经验就建筑施工企业对施工成本的控制谈谈一自己的认识和看法.     

从数据结构角度设计导游系统

从数据结构角度为旅游胜地设计导游系统。向游人提供景点的信息查询服务,根据指定的景点提供相关的景点信息。任意给定起点和终点,查询两点之间的最短路径。     

论现行行政事业单位财务会计制度和现实会计处理的矛盾

随着我国市场经济的发展与管理体制的不断改革，财会管理制度相对落后于现实工作要求，使实际工作缺乏相关规范性的指导。本文从实践出发，在分析了这一规则与实务间的矛盾后，提出对行政事业单位财务规则及会计制度的几项修改建议。     

Mobility Influences on the Capacity of Wireless Cellular Networks

Capacity has always been a major concern in wireless networks. This letter studies the impact of mobility on the overall system capacity in wireless cellular networks. In this letter, we present a simple system model which we developed to capture the inherent relationships among system capacity, new call blocking probability, handoff dropping probability, call terminating probability, and bandwidth utilization rate. We investigate the complex relationship between mobility and capacity‐related parameters. Through simulation, we demonstrate that mobility has a significant impact on capacity and is reversely proportional to the bandwidth reserved for handoff traffic.     

An overview of ultra-wideband microwave imaging via space-time beamforming for early-stage breast-cancer detection

Ultra-wideband (UWB) microwave imaging has recently been proposed for detecting small malignant breast tumors. In this article, we review the current research status of this approach. First, we introduce the concept of microwave imaging via space-time (MIST) beamforming and related signal-processing algorithms. The objective of these signal-processing techniques is to form a spatial image of scattered microwave energy, and to identify the presence and location of malignant lesions from their scattering signatures. Next, we present numerical studies based on finite-difference time-domain simulations to demonstrate the efficacy of MIST beamforming for detecting small malignant breast lesions in both prone and supine configurations. Finally, the experimental feasibility of UWB microwave imaging is demonstrated using an initial imaging prototype and multilayered breast phantoms.