Concept and requirements of sustainable development in bridge engineering

The concept of sustainability is described in this paper using a single sustainable principle,two goals of sustainable development,three dimensions of sustainable engineering,four sustainable requirements and five phases of sustainable construction.Four sustainable requirements and their practice in China are discussed in particular.The safe reliability of bridges is first compared with the events of bridge failure in China and in the rest of the world and followed by structural durability,including the cracking of concrete cable-stayed bridges,deflection of concrete girder bridges and fatigue cracks of orthotropic steel decks.With respect to functional adaptability,lateral wind action on vehicles and its improvement are introduced regarding a sea-crossing bridge located in a typhoon-prone area.The Chinese practice of using two double main span suspension bridges and a twin parallel deck cable-stayed bridge is presented in discussing the final sustainable requirement:capacity extensibility.

Engineering crop nutrient efficiency for sustainable agriculture

Increasing crop yields can provide food,animal feed, bioenergy feedstocks and biomaterials to meet increasing global demand; however, the methods used to increase yield can negatively affect sustainability. For example, application of excess fertilizer can generate and maintain high yields but also increases input costs and contributes to environmental damage through eutrophication, soil acidification and air pollution. Improving crop nutrient efficiency can improve agricultural sustainability by increasing yield while decreasing input costs and harmful environmental effects. Here, we review the mechanisms of nutrient efficiency(primarily for nitrogen, phosphorus, potassium and iron) and breeding strategies for improving this trait, along with the role of regulation of gene expression in enhancing crop nutrient efficiency to increase yields. We focus on the importance of root system architecture to improve nutrient acquisition efficiency, as well as the contributions of mineral translocation, remobilization and metabolic efficiency to nutrient utilization efficiency.

Optimization of gas turbines for sustainable turbojet propulsion

Gas-turbines are widely used to power aero planes because they are light,compact with a high power-to-weight ratio.In the turbo jet engine,the main operating variables are:compressor pressure ratio rp and turbine inlet temperature(TIT).These variables affect the specific thrust and specific fuel consumption(SFC),which represent the main performance parameters.In addition to the analytical work,a computer program of the General Algebraic Modeling System(GAMS)was used for analysis and optimization.The analysis shows that the specific thrust strongly depends on turbine inlet temperature(TIT),where a 10%decrease in TIT results in 6.7%decrease in specific thrust and 6.8%decrease in SFC.Furthermore,the value of optimum pressure ratio rf for maximum specific thrust increases with TIT.A 10%decrease from design TIT results in 11.43%decrease in rf.The value of optimum pressure ratio for the turbojet engine operating at Ma=0.8 and altitude Alt=13000 m,and TIT=1700 K was found to be 14.&2015 National Laboratory for Aeronautics and Astronautics.Production and hosting by Elsevier B.V.

DATA DRIVEN MODELING FOR POWER TRANSFORMER LIFESPAN EVALUATION

Large sized power transformers are important parts of the power supply chain. These very critical networks of engineering assets are an essential base of a nation＇s energy resource infrastructure. This research identifies the key factors influencing transformer normal operating conditions and predicts the asset management lifespan. Engineering asset research has developed few lifespan forecasting methods combining real-time monitoring solutions for transformer maintenance and replacement. Utilizing the rich data source from a remote terminal unit （RTU） system for sensor-data driven analysis, this research develops an innovative real-time lifespan forecasting approach applying logistic regression based on the Weibull distribution. The methodology and the implementation prototype are verified using a data series from 161 kV transformers to evaluate the efficiency and accuracy for energy sector applications. The asset stakeholders and suppliers significantly benefit from the real-time power transformer lifespan evaluation for maintenance and replacement decision support.