31,487 research outputs found
Recommended from our members
Nonthermal Mg I Emission At 12 Micron From Procyon
We report on stellar Mg i emission at 12 mu m from alpha CMi (Procyon), a star slightly hotter than the Sun. Solar Mg i emission is well known, and its formation was successfully explained in detail by Carlsson et al. Here, for the first time, we successfully model and compare synthetic spectra of the emission lines at 12 mu m with observations of a star other than the Sun. The use of these lines as stellar diagnostics has been anticipated for 10 years or more (see, e.g., Carlsson et al.). We find that the model reproduces the observed emission in Procyon quite well. We expect that high-resolution spectrographs on 8-10 m telescopes will finally be able to exploit these new diagnostics.Swedish Research Councils VRSTINTNSF AST 03-07497Texas Advanced Research ProgramAstronom
An analysis of security issues in building automation systems
The purpose of Building Automation Systems (BAS) is to centralise the management of a wide range of building services, through the use of integrated protocol and communication media. Through the use of IP-based communication and encapsulated protocols, BAS are increasingly being connected to corporate networks and also being remotely accessed for management purposes, both for convenience and emergency purposes. These protocols, however, were not designed with security as a primary requirement, thus the majority of systems operate with sub-standard or non-existent security implementations, relying on security through obscurity. Research has been undertaken into addressing the shortfalls of security implementations in BAS, however defining the threats against BAS, and detection of these threats is an area that is particularly lacking. This paper presents an overview of the current security measures in BAS, outlining key issues, and methods that can be improved to protect cyber physical systems against the increasing threat of cyber terrorism and hacktivism. Future research aims to further evaluate and improve the detection systems used in BAS through first defining the threats and then applying and evaluating machine learning algorithms for traffic classification and IDS profiling capable of operating on resource constrained BAS
Empirical Study of Car License Plates Recognition
The number of vehicles on the road has increased drastically in recent years. The license plate is an identity card for a vehicle. It can map to the owner and further information about vehicle. License plate information is useful to help traffic management systems. For example, traffic management systems can check for vehicles moving at speeds not permitted by law and can also be installed in parking areas to se-cure the entrance or exit way for vehicles. License plate recognition algorithms have been proposed by many researchers. License plate recognition requires license plate detection, segmentation, and charac-ters recognition. The algorithm detects the position of a license plate and extracts the characters. Various license plate recognition algorithms have been implemented, and each algorithm has its strengths and weaknesses. In this research, I implement three algorithms for detecting license plates, three algorithms for segmenting license plates, and two algorithms for recognizing license plate characters. I evaluate each of these algorithms on the same two datasets, one from Greece and one from Thailand. For detecting li-cense plates, the best result is obtained by a Haar cascade algorithm. After the best result of license plate detection is obtained, for the segmentation part a Laplacian based method has the highest accuracy. Last, the license plate recognition experiment shows that a neural network has better accuracy than other algo-rithm. I summarize and analyze the overall performance of each method for comparison
Dynamic Scoring: A Back-of-the-Envelope Guide
This paper uses the neoclassical growth model to examine the extent to which a tax cut pays for itself through higher economic growth. The model yields simple expressions for the steady-state feedback effect of a tax cut. The feedback is surprisingly large: for standard parameter values, half of a capital tax cut is self-financing. The paper considers various generalizations of the basic model, including elastic labor supply, departures from infinite horizons, and non-neoclassical production settings. It also examines how the steady-state results are modified when one considers the transition path to the steady state.
- ā¦