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We analyze the MAC access delay of the IEEE 802.11e EDCA mechanism under saturation. We develop a detailed analytical model to evaluate the influence of all EDCA differentiation parameters, namely AIFS, CWmin, CWmax and TXOP limit, as well as the backoff multiplier beta. Explicit expressions for the mean, standard deviation and generating function of the(More)
We compare the performance of different backoff functions for the multiple access protocol in an IEEE 802.11 wireless LAN (WLAN). We provide a unified analytical model with explicit expressions for the mean and standard deviation of the access delay for generalized exponential, polynomial and linear backoff functions. Using our model, we show that linear(More)
Biomedical imaging is increasingly electronic in terms of image acquisition and display. Image detectors have become so sensitive that the amount of information acquired is greater than can be displayed at any one time without using special purpose hardware. Research in image processing methods is essential to fully exploit the information that has been(More)
To efficiently extract local and global features in face description and recognition, a pyramid-based multi-scale LBP approach is proposed. Firstly, the face image pyramid is constructed through multi-scale analysis. Then the LBP operator is applied to each level of the image pyramid to extract facial features under various scales. Finally, all the(More)
In this paper, we study the MAC access delay of EDCA in the draft IEEE 802.11e standard under saturated conditions. We obtain explicit expressions for the mean, the standard deviation and the generating function of the distribution of the access delay. By using numerical inversion on the generating function, we are able to compute values of the(More)
This paper describes a fast and simple training method for face detection based on block orientation of the gray level gradient. The gradient orientation is one of the most essential features to describe the image structure. In this paper, the detector is trained just by the positive samples from which the feature value repeat times are regarded as the(More)
Solder paste plays a critical role in SMT (surface mount technology) and reflow soldering. And flux is an important material in composition of solder paste. Due to the drive towards lead-free electronic packaging and no-clean soldering technology, a new no-clean flux contained composite activators was formulated specifically for lead-free paste. Spread test(More)
This paper describes a fast and simple training method for face detection based on block gradient of the gray level. The gradient orientation is one of the most essential features to describe the image structure. In this paper, the detector is trained just by the positive samples from which the feature values accumulated are regarded as the values' weight(More)
Article history: Received: 4.9.2015. Received in revised form: 1.12.2015. Accepted: 2.12.2015. This research paper deals with the joining of different materials such as SiCp/6063Al MMCs and Fe-Ni alloys by means of vacuum brazing with active filler metal Ag47-Cu18-In17-Sn17-Ti1. With the optimal process parameters, i.e., brazing temperature 580 °C, soaking(More)
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