Airport traffic complexity and environment efficiency metrics for evaluation of ATM measures

For a given (current or planned) traffic demand, different air traffic management measures could result in different airport traffic complexity and efficiency. This paper presents the research on the relationship between airport traffic complexity and time and environmental efficiency for different air traffic control (ATC) tactics applied to the given or planned airport layout. Emphasis is placed on the evaluation of airport traffic complexity, aircraft fuel consumption, gas emissions and time efficiency for different ATC tactics and/or airport airfield layouts. For busy airports during peak hours, arrival queuing delays, taxi-in, taxi-out times and departure queuing delays increase, which induces additional unnecessary fuel consumption, gas emission and time inefficiency. In order to find a tool which could indicate potential delay generators, a measure of airport traffic complexity – called Dynamic Complexity is proposed. Experiments were performed for airports with different airfield layouts, for different traffic demands and ATC applied tactics using SIMMOD simulation model. Traffic situations were analyzed and delays were measured. The values of airport traffic complexity, fuel consumption and gas emissions were also determined. A comparative analysis of the results show: first, the proposed airport traffic complexity metric quite satisfactorily reflects the influence of traffic characteristics upon the environmental state of the system, and second, different ATM strategic and tactical measures (airport airfield infrastructure development and applied ATC tactics) could significantly reduce traffic complexity and increase time and environmental efficiency at the airport.     

Transformation of the Information Technology Function in Organizations: A Case Study in the Manufacturing Sector

The main goal of this study is to better understand the nature of transformations of the Information Technology (IT) function in organizations. A conceptual framework combining a typology of the IT function and key elements of the theory of punctuated equilibrium was developed and applied in a case study of a manufacturing company. Our results suggest that IT functions are transformed in response to various pressures that push it toward change. However, these pressures need to be channelled through a catalyst consisting of three independent elements: (a) the vision of the enterprise concerning the potential value of IT tools, (b) the degree of Chief Information Officer's participation in strategic decision making, and (c) the level of IT knowledge among members of the executive team. Finally, our results challenge the notion that all IT functions tend towards the same optimal profile over time. Copyright © 2011 ASAC. Published by John Wiley & Sons, Ltd.     

用TPS54xx设计DC/DC转换电路

DC/DC转换电路相对线性稳压电路以其能量转换效率高,芯片发热少,可升压可降压可反向转换等优点正广泛地应用于各种电路之中,如何设计DC/DC转换电路是电子电路开发人员所必须掌握的。TI公司的TPS54xx系列芯片是非隔离型的降压DC/DC转换芯片,该系列的芯片具有转换效率高,输入电压范围宽,输出电流大,工作频率高(能够减小外围器件的尺寸和成本)等优点,正广泛地应用于各种电子电路中。以TPS5430为例讲述TPS54xx系列芯片的设计方法。