Retrodirective Antenna Array Using High Frequency Offset

The paper deals with the design of a simple retrodirective antenna array exhibiting by high frequency offset between received and transmitted wave. Analysis of the beam pointing error using antenna array model developed in MATLAB is described. The frequencies of transmitted wave and received wave are chosen on the basis of this analysis. Then a suitable structure for further design is determined and particular blocks of complete retrodirective antenna array are briefly described and their measured parameters are presented. Relatively high frequency offset between received and transmitted wave makes it possible to use frequency filters for received and transmitted signal separation which led to significant reduction of the circuit complexity

Mathematical Model of Cold Cap?Preliminary One-Dimensional Model Development

The ultimate goal of batch-melting studies, laboratory-scale, large-scale, or mathematical modeling is to increase the rate of glass processing in an energy-efficient manner. Mathematical models are not merely an intermediate step between laboratory-scale and large-scale studies, but are also an important tool for assessing the responses of melters to vast combinations of process parameters. In the simplest melting situation considered in this study, a cold cap of uniform thickness rests on a pool of molten glass from which it receives a steady uniform heat flux. Thus, as the feed-to-glass conversion proceeds, the temperature, velocity, and extent of feed reactions are functions of the position along the vertical coordinate, and these functions do not vary with time. This model is used for the sensitivity analyses on the effects of key parameters on the cold-cap behavior

The Security Testbed for the Purposes of the ITS-G5 Communication Attacks Prevention

Secure communication in the Intelligent Transport System (ITS) plays a crucial role in vehicular safety. Security threats can be an unwanted cause of congestions and attacks. In this paper, first, the security threats in ITS are described and discussed. Second, a concept of the security testbed for ITS-G5 communication was presented. Its purpose is to test or verify the security threats for the machine-to-machine communication in the ITS. The testbed is composed of two parts. The first part represents the vehicle, and the second part is the Road-Side Unit (RSU) or the Road-vehicle unit (RVU). The testbed contains Arduino-type modules, SPI interface to CAN bus converter, and ELM 327 diagnostic tool supporting all communication protocols of the OBD standard. The simulator presented in this article was practically implemented and the functionality verified by experimental testing. Finally, a message for remote speed limiting was implemented on the testbed for further security testing.Peer reviewe

Influence of heat treatment-induced residual stress on residual fatigue life of railway axles

Assessment of residual fatigue life of railway axles commonly does not include effect of residual stress. This paper presents advanced methodology for estimation of residual fatigue life of railway axles considering not only external loading but also internal residual stresses. The studied axles made of the EA4T steel were treated by induction hardening in order to generate very high compressive residual stress in the surface layer of the axle. Such residual stress has positive effect on behaviour of surface defects and leads to fatigue crack retardation or even crack arrest and, consequently, to immense prolongation of residual fatigue life. Experimentally measured data of residual stress were implemented in a numerical model in order to determine the true stress state in the axle. The model included a crack and took the effects of bending, press fit and residual stress into account. Residual fatigue life was calculated for various starting crack lengths based on the experimentally determined da/dN-ΔK curves for various load ratios. Finally, the results for axles hardened by standard method and by induction hardening were compared with residual fatigue lives obtained experimentally from fatigue tests on real railway axles with artificial cracks. The calculated values were conservative with good agreement with experimental dat

Challenges and science-based implications for modern management and conservation of European ungulate populations

Wildlife management systems face growing challenges to cope with increasingly complex interactions between wildlife populations, the environment and human activities. In this position statement, we address the most important issues characterising current ungulate conservation and management in Europe. We present some key points arising from ecological research that may be critical for a reassessment of ungulate management in the future. Ecosystem . Population sustainability . Science-basedmanagement .Wildlifemanagement .Adaptive managemen

Towards long-term standardised carbon and greenhouse gas observations for monitoring Europe's terrestrial ecosystems : a review

Research infrastructures play a key role in launching a new generation of integrated long-term, geographically distributed observation programmes designed to monitor climate change, better understand its impacts on global ecosystems, and evaluate possible mitigation and adaptation strategies. The pan-European Integrated Carbon Observation System combines carbon and greenhouse gas (GHG; CO2, CH4, N2O, H2O) observations within the atmosphere, terrestrial ecosystems and oceans. High-precision measurements are obtained using standardised methodologies, are centrally processed and openly available in a traceable and verifiable fashion in combination with detailed metadata. The Integrated Carbon Observation System ecosystem station network aims to sample climate and land-cover variability across Europe. In addition to GHG flux measurements, a large set of complementary data (including management practices, vegetation and soil characteristics) is collected to support the interpretation, spatial upscaling and modelling of observed ecosystem carbon and GHG dynamics. The applied sampling design was developed and formulated in protocols by the scientific community, representing a trade-off between an ideal dataset and practical feasibility. The use of open-access, high-quality and multi-level data products by different user communities is crucial for the Integrated Carbon Observation System in order to achieve its scientific potential and societal value.Peer reviewe

A remark on energy optimal strategies for a train movement

This article introduces the notion of the critical time in the problem of the energy efficient train control and its calculation in some particular cases. We apply some results of non-linear parametric optimization to show that the number of optimal control levels depends on the relation between the given time of the journey and this critical time. Furthermore, we derive equations for the computation of the switching times. I emphasise exact forms of solutions with a minimal use of numerical mathematics. The results can be used to find the values of the switching times only by solving algebraic equations and to analyse the behaviour of the results with respect to given entry parameters of the problem. References P. Horn. Uber die Anwendung des Maximum-Prinzips von Pontrjagin zur Ermittlung von Algorithmen fur eine energieoptimale Zugsteuerung (About the application of the Pontryagin principle for deriving of the algorithms for an energetically optimal control of a train). Wissensch. Zschr. d. Hochschule fur Verkehrswessen ``Friedrich List'', 18(4):919--943, 1971. (in German). P. Howlett. An optimal strategy for the control of a train. J. Austral. Math. Soc., Ser. B, 31:454--471, 1990. http://anziamj.austms.org.au/V31/part4/Howlett.html. P. Howlett and J. Cheng. Optimal driving strategies for a train on a track with continuously varying gradient. J. Austral. Math. Soc., Ser. B, 38:388--410, 1997. http://anziamj.austms.org.au/V38/part3/Howlett.html. P. G. Howlett. The optimal control of a train. Annals of OR, 98:65--87, 2000. http://www.ingentaconnect.com/content/klu/anor/2000/00000098/F0040001/0%332912. P. G. Howlett and J. Cheng. A note on the calculation of optimal strategies for the minimisation of fuel consumption in the control of trains. IEEE Transactions on Automatic Control, 38(11):1730--1734, 1993. doi:10.1109/9.262051. P. G. Howlett and A. Leizarowitz. Optimal strategies for vehicle control problems with finite control sets. Dynamics of Continuous, Discrete and Impulsive Systems, B: Applications and Algorithms, 8:41--69, 2001. P. G. Howlett and P. J. Pudney. Energy efficient train control. Springer, London, 1995. E. Khmelnitsky. On an optimal control problem of train operation. IEEE Transactions on Automatic Control, 45:1257--1266, 2000. doi:10.1109/9.867018. K. P. Li, Z. Y. Gao, and B. H. Mao. Energy-optimal control model for train movements. Chinese Physics, 16(2):359--364, 2007. doi:10.1088/1009-1963/16/2/015. R. Liu and I. Golovitcher. Energy efficient operation of rail vehicles. Transportation Research Part A: Policy and Practice, Elsevier, United Kingdom, 37:917--932, 2003. doi:10.1109/ICSMC.2001.969927. B. Bank. Non-Linear Parametric Optimization. Akademie-Verlag, Berlin, 1982. R. Pickhardt. Time- and energy- optimal control of an electric railcar. In Intelligent Transportation Systems, 2000. Proceedings. 2000 IEEE, pages 500--505, 2000. doi:10.1109/ITSC.2000.881120. P. Pudney and P. Howlett. Optimal driving strategies for a train journey with speed limits. J. Austral. Math. Soc., Ser. B, 36:38--49, 1994. http://anziamj.austms.org.au/V36/part1/Pudney.html. M. F. Bazaraa, H. D. Sherali, and C. M. Shetty. Nonlinear Programming, Theory and Algorithms. John Wiley and Sons, New York, 1993. J. Cheng, Y. Davydova, P. G. Howlett, and P. J. Pudney. Optimal driving strategies for a train journey with non-zero track gradient and speed limits. IMA Journal of Mathematics Applied in Business and Industry, 10:89--115, 1999. doi:10.1093/imaman/10.2.89. S. H. Han, Y. S. Byen, J. H. Baek, T. K. An, S. G. Lee, and H. J. Park. An optimal automatic train operation (ato) control using genetic algorithms (ga). In TENCON 99. Proceedings of the IEEE Region 10 Conference, volume 1, pages 360--362, 1999. doi:10.1109/TENCON.1999.818425

REFINING OEM TO IMPROVE FEATURES OF QUERY LANGUAGES FOR SEMISTRUCTURED DATA

Semistructured data can be explained as “schemaless ” or “self-describing”, indicating that there is no separate description of the type or structure of the data. This is in contrast with the structured approaches, such, e.g. relational databases, where the data structure is usually designed first and described as a database schema. Semistructure