城市道路环形交叉口车辆排队及行车延误研究

随着国民经济的快速发展,城市机动车保有量持续增加,由此引起了一系列的交通问题.结合北京市东四十条桥环形交叉口的交通状况,采用VISSIM交通微观仿真系统,对环形交叉口车辆排队及行车延误进行了分析研究,得出了车辆排队及延误与通行能力影响因素之间的关系.     

环境美学视野中的山水城市理念

从阐述宜居城市的内涵出发,提出乐居是宜居的最高境界,并进而在此基础上,透过环境美学的视野,分析了山水城市理念与城市乐居追求的内在关联,指出环境美学试图营造的让人乐居的理想居住环境,实际上与山水城市的理念殊途同归．     

A practical image reconstruction and processing method for symmetrically off-center detector CBCT system

CBCT scanners have been widely used in angiography, radiotherapy guidance, mammography and oral maxillofacial imaging. To cut detector size, reduce manufacturing costs and radiation dose while keeping a reasonable FOV, the flat panel detector can be placed off-center horizontally. This scanning configuration extends the FOV effectively. However, each projection is transversely truncated, bringing errors and artifacts in reconstruction. In this paper, a simple but practical method is proposed for this scanning geometry based on truncation compensation and the modified FDK algorithm. Numerical simulations with jaw phantom were conducted to evaluate the accuracy and practicability of the proposed method. A novel CBCT system for maxillofacial imaging is used for clinical test, which is equipped with an off-center small size flat panel detector. Results show that reconstruction accuracy is acceptable for clinical use, and the image quality appears sufficient for specific diagnostic requirements. It provides a novel solution for clinical CBCT system, in order to reduce radiation dose and manufacturing cost.     

重庆市秀山县老田庄锰矿地质特征及矿床成因分析

南华系下统大塘坡组第一段为本区的含锰岩系,其厚度及岩性组合与锰矿有着直接的关系。本区锰矿属沉积菱锰矿矿床类型,具有多层含矿性。古地理、古构造对锰矿沉积的控制作用,在还原环境的条件下,沉积了一套以含炭质水云母页岩为主的黑色含锰岩系地层,锰矿即产于含锰岩系地层之底部。     

Wisdom City Management System Based on Internet-of-Things Technology

The city management model of China was extensive administrative management model from the beginning. From the end of the 20th century to the first decade of 21st century, China began the systematic construction and through software system, realizes digital and automatic city management system construction. At present, with the perfection and wide applying of internet-of-things technology, it is possible to build the wisdom city management system based on internet-of-things technology. Wisdom city management system is the upgrading city management system of the digital city and the automatic city. This paper, from the basic concept and basic application of internet-of-things technology, discusses the overall structure, application and value, significance and risk of the wisdom city management system. From the perspective of the work mechanism of city management enforcement department, and based on the internet-of-things technology, this paper probes into the wisdom city management system with the “cover to the surface, monitoring to the line, and control to the point” information acquisition, scheduling and decision-making. It also expounds the function and content in detail from the percep-tion layer, the transport layer, support layer and application layer of the wisdom city management system. It pro-vides the actual maneuverability reference of the construction of wisdom city management system based on the internet-of-things technology.     

城市化与工业化的因果关系——以安徽省宿州市为例

利用安徽省宿州市1999—2010年的统计数据,运用塞尔奎因-钱纳里标准法分析其城市化与工业化发展阶段,采用协整检验、Granger因果检验对其城市化与工业化的因果关系进行实证研究。结果表明：1）宿州工业化和城市化水平低于全国平均水平,均处于初期发展阶段;2）宿州城市化与工业化有高度相关关系,城市化滞后于工业化;3）宿州当前城市化发展是工业化发展的Granger原因,加快城市化发展有利于促进工业化水平提高;4）宿州城市化水平与第二产业增加值比重和第三产业增加值比重具有长期稳定的协整关系,但与非农就业人口比重不存在长期稳定的均衡关系;5）宿州城市化水平与第二产业增加值比重和第三产业增加值比重的弹性系数分别为0.21和0.86,说明其城市化水平对第三产业的拉动作用要比对第二产业的拉动作用更大一些。因此宿州市应促进人口向中心城区的集聚,发挥城市化对工业化的促进作用。     

基于径向基网络的燃气短期负荷预测

用径向基（RBF）神经网络对城市燃气系统进行短期负荷预测。在对鞍山市燃气系统的历史负荷数据进行短期预测结果表明，所建立的RBF神经网络模型具有较高的预测精度。     

重庆市荆襄式磷矿地质特征及成矿规律分析

重庆市荆襄式磷矿主要分布在渝东北的城口—巫山一带。评述了该类磷矿地层、构造、成矿特征等,总结了荆襄式磷矿成矿规律,为重庆市磷矿资源找矿及预测提供参考。     

末端电磁搅拌参数对帘线钢72A铸坯中心碳偏析的影响

帘线钢72A(%:0.71～0.72C、0.50～0.60Mn、0.22～0.30Si、≤0.010P、≤0.008S)的冶炼工艺流程为铁水预处理-LD-LF-RH-CC-200 mm×200 mm连铸。在连铸时钢水过热度10～20℃,拉速0.98 m/min,二冷比水量0.32 L/kg,结晶器冷却水220 m³/h,结晶器电磁搅拌1.5 Hz、500 A的条件下进行了末端电磁搅拌(F-EMS)的工艺研究。结果表明,当离钢液弯月面8 m处以18 Hz、450 A进行F-EMS,可使帘线钢72A铸坯的中心碳偏析指数≤1.05。     

热轧材冷拉过程65钢硬线断裂分析

65钢(/%:0.62～0.。70C、0.18～0.28Si、0.55～O.75Mn)硬线盘条的生产流程为120 t转炉-LF-170mm×170 mm连铸-高速线材轧制。采用光学和扫描电子显微镜分析了65钢φ6.5 mm热轧盘条在冷拉至φ1.85mm过程中断裂的原因。实验结果表明,断口宏观特征为笔尖状,盘条横截面组织均匀性较差;裂纹起源于心部粗大的先共析铁素体和粗片状渗碳体,断裂的主要原因是索氏体化率低,存在大块先共析铁素体和中心碳偏析。