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991.
Yi Ouyang 《Signal, Image and Video Processing》2017,11(6):1097-1104
In this paper, we propose a tracking algorithm that can robustly handle appearance variations in tracking process. Our method is based on seeds–active appearance model, which is composed by structural sparse coding. In order to compensate for illumination changes, heavy occlusion and appearance self-updating problem, we proposed a mixture online learning scheme for modeling the target object appearance model. The proposed object tracking scheme involves three stages: training, detection and tracking. In the training stage, an incremental SVM model that directly measures the candidates samples and target difference. The proposed mixture generate–discriminative method can well separate two highly correlated positive candidates images. In the detection stage, the trained weighted vector is used to separate the target object in positive candidates images with respect to the seeds images. In the tracking stage, we employ the particle filter to track the object through an appearance adaptive updating algorithm with seeds–active constrained sparse representation. Based on a set of comprehensive experiments, our algorithm has demonstrated better performance than alternatives reported in the current literature. 相似文献
992.
Shahin Tajik Enrico Dietz Sven Frohmann Helmar Dittrich Dmitry Nedospasov Clemens Helfmeier Jean-Pierre Seifert Christian Boit Heinz-Wilhelm Hübers 《Journal of Cryptology》2017,30(2):550-571
As intended by its name, physically unclonable functions (PUFs) are considered as an ultimate solution to deal with insecure storage, hardware counterfeiting, and many other security problems. However, many different successful attacks have already revealed vulnerabilities of certain digital intrinsic PUFs. This paper demonstrates that legacy arbiter PUF and its popular extended versions (i.e., feed-forward and XOR-enhanced) can be completely and linearly characterized by means of photonic emission analysis. Our experimental setup is capable of measuring every PUF internal delay with a resolution of 6 ps. Due to this resolution, we indeed require only the theoretical minimum number of linear independent equations (i.e., physical measurements) to directly solve the underlying inhomogeneous linear system. Moreover, it is not required to know the actual PUF responses for our physical delay extraction. We present our practical results for an arbiter PUF implementation on a complex programmable logic device manufactured with a 180 nm process. Finally, we give an insight into photonic emission analysis of arbiter PUF on smaller chip architectures by performing experiments on a field programmable gate array manufactured with a 60 nm process. 相似文献
993.
In order to measure the range, angle, and Doppler frequency of the target without any synchronization in the bistatic radar, a novel complete parameter estimation method based on separability of a pair of Linear Frequency Modulation (LFM) signal is presented. The Doppler frequency is measured by the time difference between two peak positions corresponding to the positive and the negative LFM return signal respectively. Direction Of Departures (DODs) and Direction Of Arrivals (DOAs) of the target are estimated by constructing a special eigenmatrix in which the estimated angles can be extracted from the eigenvalue or the eigenvector. The target position can be located in the presence of the estimated DODs, DOAs and the signal delay difference between the echo and the directive wave signal in Multiple Input Multiple Output (MIMO) bistatic radar without any synchronization. The correctness and effectiveness of the proposed method are verified by the computer simulation. 相似文献
994.
Wuhu Li 《Journal of Electronic Materials》2010,39(3):295-302
In this study, an Ar plasma was employed to remove the antitarnish layer on Ag-plated Cu leadframe surfaces using various process powers and times. Measurements of the contact angle, field-emission scanning electron microscopy, x-ray photoelectron spectroscopy, and time-of-flight secondary-ion mass spectrometry were employed to characterize both the Ag and Cu surfaces before and after plasma cleaning. The antitarnish layer on the leadframe surfaces was determined to be benzotriazole and/or its derivatives. Low-power and short-duration plasma treatments did not significantly change the Ag and Cu surfaces in terms of their surface morphologies, and such treatments were not able to totally remove the antitarnish layer. In contrast, a high-power and long-duration plasma treatment made the surfaces slightly smoother and was able to remove the antitarnish layer on both Ag and Cu surfaces. However, cross-contaminations were also detected between the Ag and Cu surfaces during the plasma cleaning process. This cross-contamination is due to redeposition of Ag and Cu atoms during the plasma treatment. 相似文献
995.
Qing Yang Alvin Lim Shuang Li Jian Fang Prathima Agrawal 《Mobile Networks and Applications》2010,15(1):36-60
Multi-hop vehicle-to-vehicle communication is useful for supporting many vehicular applications that provide drivers with
safety and convenience. Developing multi-hop communication in vehicular ad hoc networks (VANET) is a challenging problem due
to the rapidly changing topology and frequent network disconnections, which cause failure or inefficiency in traditional ad
hoc routing protocols. We propose an adaptive connectivity aware routing (ACAR) protocol that addresses these problems by
adaptively selecting an optimal route with the best network transmission quality based on statistical and real-time density
data that are gathered through an on-the-fly density collection process. The protocol consists of two parts: 1) select an
optimal route, consisting of road segments, with the best estimated transmission quality, and 2) in each road segment of the
chosen route, select the most efficient multi-hop path that will improve the delivery ratio and throughput. The optimal route
is selected using our transmission quality model that takes into account vehicle densities and traffic light periods to estimate
the probability of network connectivity and data delivery ratio for transmitting packets. Our simulation results show that
the proposed ACAR protocol outperforms existing VANET routing protocols in terms of data delivery ratio, throughput and data
packet delay. Since the proposed model is not constrained by network densities, the ACAR protocol is suitable for both daytime
and nighttime city VANET scenarios. 相似文献
996.
This paper focuses on vehicle to roadside (V2R) communications in vehicular networks based on the IEEE 802.11 DCF MAC protocol.
In vehicular networks, roadside units (RSUs) are typically spaced apart along the road and each vehicle can be connected to
an RSU only when the vehicle is within its transmission range. Due to the high relative speed between a moving vehicle and
a stationary RSU, the residence time of the vehicle within the coverage of each RSU is very short. Thus it is hard for the
system to reach a steady state. With multi-hop forwarding, in which a vehicle may be connected to an RSU through relaying
over other vehicles, the connection time of each V2R access may be extended. But this is at the expense of introducing wireless
interference among vehicles, which may dramatically degrade the system performance. To tackle these challenges, we propose
a new mechanism called Proxy-based Vehicle to RSU access (PVR) for V2R communications. This protocol is designed to exploit
cooperative and opportunistic forwarding between any two distant RSUs and to emulate back-to-back transmissions within the
coverage of an RSU. As a result, it can shorten the access delay by taking advantage of opportunistic forwarding and mitigate
the interference problem during the short residence time within the coverage of an RSU. The simulation results show that PVR
achieves excellent performance and outperforms all existing solutions for V2R communications in vehicular networks. 相似文献
997.
We consider the problem of static transmission-power assignment for lifetime maximization of a wireless sensor network with stationary nodes operating in a data-gathering scenario. Using a graph-theoretic approach, we propose two distributed algorithms, MLS and BSpan, that construct spanning trees with minimum maximum (minmax) edge cost. MLS is based on computation of minmax-cost paths from a reference node, while BSpan performs a binary search over the range of power levels and exploits the wireless broadcast advantage. We also present a simple distributed method for pruning a graph to its Relative Neighborhood Graph, which reduces the worst-case message complexity of MLS under natural assumptions on the path-loss. In our network simulations both MLS and BSpan significantly outperform the recently proposed Distributed Min–Max Tree algorithm in terms of number of messages required. 相似文献
998.
The separation of cochannel signals is of interest in communication community. Some algorithms based on constant modulus (CM)
have been previously developed to separate cochannel signals with the assumption of Gaussian channel noise. The mismatches
of noise models between the assumed channel noise and the practical noise may occur. These mismatches will inevitably lead
the performance of cochannel signals separation to degrade. In this paper the alpha-stable distribution is employed as noise
model to simulate impulsive noise occurring in wireless channel. A constant modulus algorithm is proposed to separate the
cochannel signals based on fractional lower-order statistics (FLOS). The convergence of the CM array is analyzed. Numerical
simulations are presented to verify the accuracy of the analytical results. 相似文献
999.
Two-Tier,Scalable and Highly Resilient Key Predistribution Scheme for Location-Aware Wireless Sensor Network Deployments 总被引:1,自引:0,他引:1
We propose a probabilistic key predistribution scheme for wireless sensor networks, where keying materials are distributed
to sensor nodes for secure communication. We use a two-tier approach in which there are two types of nodes: regular nodes
and agent nodes. Agent nodes are more capable than regular nodes. Our node deployment model is zone-based such that the nodes
that may end up with closer positions on ground are grouped together. The keying material of nodes that belong to different
zones is non-overlapping. However, it is still possible for nodes that belong to different zones to communicate with each
other via agent nodes when needed. We give a comparative analysis of our scheme through simulations and show that our scheme
provides good connectivity figures at reasonable communication cost by using minimal flooding in key distribution. Moreover,
we show that our scheme is scalable such that no extra overhead in incurred in case of increased number of nodes and sensor
field size. Most importantly, simulation results show that our scheme is highly resilient to node captures. 相似文献
1000.
Muhammad Taher Abuelma’ati 《Analog Integrated Circuits and Signal Processing》2010,65(3):419-428
Using a unified representation for a class of the two current-feedback operational amplifier (CFOA) sinusoidal oscillators,
new circuits of this type can be systematically discovered. A catalogue of two circuit structures, each structure realizing
18 oscillator circuits, is presented. Moreover, using the RC:CR transformation, additional 18 oscillator circuits can be obtained
from each structure. A third structure realizing additional two oscillator circuits is also presented. Some of the circuits
enjoy one or more of the following attractive features: use of grounded capacitors, feasibility of absorbing the parasitic
components of the CFOAs, availability of a buffered output voltage and orthogonal tuning of the frequency and the startup
condition of oscillation. Moreover, it is shown that the use of the Barkhausen criterion for the determination of the startup
condition of oscillation and the frequency of oscillation yields inaccurate results with relatively large errors depending
on the selected component values. Furthermore, it is shown that using the roots of the characteristic equation of a specific
oscillator structure will result in a startup condition that cannot be adjusted without disturbing the frequency of oscillation. 相似文献