旅游景区三维立体网络覆盖方案的研究及应用

随着旅游业的发展,节假日各景区游客日益增多甚至爆满,同时游客对景区的网络质量要求也越来越高。在目前降本增效的大趋势下,如何利用有限的资源实现最好的覆盖显得尤为重要。本文根据张家界景区的实际地形、游客分布及建筑情况等提出了“点、线、面”的三维立体覆盖方案,全面提升景区无线网络覆盖能力,成功打造精品网络。     

An economic investigation of the wind-hydrogen projects: A case study

Hydrogen as an energy carrier can play a significant role in reducing environmental emissions if it is produced from renewable energy resources. This research aims to assess hydrogen production from wind energy considering environmental, economic, and technical aspect for the East Azerbaijan province of Iran. The economic assessment is performed by calculation of payback period, levelized cost of hydrogen, and levelized cost of electricity. Since uncertainty in the power output of wind turbines may affect the payback period, all calculations are performed for four different turbine degradation rates. While it is common in the literature to choose the wind turbine based on a single criterion, this study implements Multi-Criteria Decision-Making (MCDM) techniques for this purpose. The results of Step-wise Weight Assessment Ratio Analysis illustrates that economic issue is the most important criterion for this research. The results of Weighted Aggregated Sum Product Assessment shows that Vestas V52 is the most suitable wind turbine for Ahar and Sarab cities, while Eovent EVA120 H-Darrieus is a better choice for other stations. The most suitable location for wind power generation is found to be Ahar, where it is estimated to annually generate 2914.8 kWh of electricity at the price of 0.045 $/kWh, and 47.2 tons of hydrogen at the price of 1.38 $/kg, which result in 583 tons of CO₂ emission reduction.     

VCR采矿法在武山铜矿应用展望

为进一步提高武山铜矿综合采矿效益，根据武山铜矿地质条件、采矿经验，并结合安全、成本、效益等因素，浅述后期生产建设过程中如何发挥现有采矿方法的优势，并针对 VCR 采矿法在武山铜矿应用现状，分析了改进提升的方法。     

Double-layer fuzzy adaptive NMPC coordinated control method of energy management and trajectory tracking for hybrid electric fixed wing UAVs

The energy management and trajectory tracking control are crucial to realize long-endurance autonomous flight for hybrid electric UAVs. This study aims to comprehensively consider energy management and trajectory tracking for hybrid electric fixed wing UAVs with photovoltaic panel/fuel cell/battery. A double-layer fuzzy adaptive nonlinear model predictive control method (DFNMPC) is proposed. Separated by the surplus demand power, energy management and trajectory tracking problem are decoupled into the high-layer fuzzy adaptive nonlinear model predictive controll problem (H-FNMPC) and low-layer fuzzy adaptive nonlinear model predictive controll problem (L-FNMPC). H-FNMPC solves the trajectory tracking and navigation control probelm for the greatest benefit of solar energy. L-FNMPC solves the power allocation problem of hybrid energy system for minimum equivalent hydrogen consumption. A fuzzy adaptive prediction horizon adjustment method based on UAV maneuvering degree is proposed to effectively improve proposed method adaptability to different mission profiles. Analogously, a fuzzy adaptive equivalent hydrogen consumption factor adjustment method in L-FNMPC is proposed to ensure the flexible utilization of battery. In addition, an equivalent hydrogen flow rate calculation method based on the real-time current ratio is proposed for PV/FC/Battery hybrid energy system. Numerical simulation results including a spiral trajectory tracking and a quadrilateral trajectory tracking, demonstrate that DFNMPC can simultaneously handle energy management and trajectory tracking problem for hybrid electric UAVs. Compared to hierarchical fuzzy state machine strategy, DFNMPC can save 13.3% hydrogen for the spiral trajectory tracking, and 56.9% for the quadrilateral trajectory tracking. It indicates that the energy efficiency can be improved from both levels of energy management and flight motion. The proposed method prospected for exploring high-energy-efficiency autonomous flight of hybrid electric UAVs in the future.     

电力工程管理中PDCA管理模式的应用

PDCA管理模式帮助电力工程管理实现了对管理过程的实时监控、信息传递和数据处理。就PDCA管理模式在电力工程中的具体运用进行了分析。     

煤焦油燃料在浮法玻璃生产中的应用

阐述了重油燃料在当前浮法玻璃生产中的使用现状,简要介绍了煤焦油代替重油的技术分析.通过煤焦油技术改造,每年可节约成本3006万元.     

冶金工程造价管理的发展趋势及对策

阐述了工程造价管理的基本内容及目标,介绍了冶金工程造价管理现状,提出了造价管理发展趋势及其对策。     

虚拟权平差的方差估计

本文基于虚拟权平差函数模型,首先推导了单位权方差σ_0~2的边缘极大似然估计(?)_0~(n~2),证明了(?)_0~(n~2)是σ_0~(n~2)的无偏、有效估计量,然后构造了σ_0~2的另一无偏估计(?)_0~2,通过平差实例验证了(?)_0~2的基本有效性.     

工程项目成本管理中存在的问题剖析

对施工企业在工程项目成本管理中存在的问题进行了分析并提出了解决办法。