21,740 research outputs found
Planckian Scattering Beyond the Eikonal Approximation in the Functional Approach
In the framework of functional integration the non-leading terms to leading
eikonal behavior of the Planckian-energy scattering amplitude are calculated by
the straight-line path approximation. We show that the allowance for the
first-order correction terms leads to the appearance of retardation effect. The
singular character of the correction terms at short distances is also noted,
and they may be lead ultimately to the appearance of non-eikonal contributions
to the scattering amplitudes.Comment: 15 pages, no figure
Instabilities in the mean field limit
Consider a system of particles interacting through Newton's second law
with Coulomb interaction potential in one spatial dimension or a
smooth potential in any dimension. We prove that in the mean
field limit , the particles system displays instabilities
in times of order for some configurations approximately distributed
according to unstable homogeneous equilibria.Comment: minor typos corrected; Journal of Statistical Physics, accepte
Ill-posedness of the hydrostatic Euler and singular Vlasov equations
In this paper, we develop an abstract framework to establish ill-posedness in
the sense of Hadamard for some nonlocal PDEs displaying unbounded unstable
spectra. We apply it to prove the ill-posedness for the hydrostatic Euler
equations as well as for the kinetic incompressible Euler equations and the
Vlasov-Dirac-Benney system
Weakly Supervised Action Localization by Sparse Temporal Pooling Network
We propose a weakly supervised temporal action localization algorithm on
untrimmed videos using convolutional neural networks. Our algorithm learns from
video-level class labels and predicts temporal intervals of human actions with
no requirement of temporal localization annotations. We design our network to
identify a sparse subset of key segments associated with target actions in a
video using an attention module and fuse the key segments through adaptive
temporal pooling. Our loss function is comprised of two terms that minimize the
video-level action classification error and enforce the sparsity of the segment
selection. At inference time, we extract and score temporal proposals using
temporal class activations and class-agnostic attentions to estimate the time
intervals that correspond to target actions. The proposed algorithm attains
state-of-the-art results on the THUMOS14 dataset and outstanding performance on
ActivityNet1.3 even with its weak supervision.Comment: Accepted to CVPR 201
Bounded Distributed Flocking Control of Nonholonomic Mobile Robots
There have been numerous studies on the problem of flocking control for
multiagent systems whose simplified models are presented in terms of point-mass
elements. Meanwhile, full dynamic models pose some challenging problems in
addressing the flocking control problem of mobile robots due to their
nonholonomic dynamic properties. Taking practical constraints into
consideration, we propose a novel approach to distributed flocking control of
nonholonomic mobile robots by bounded feedback. The flocking control objectives
consist of velocity consensus, collision avoidance, and cohesion maintenance
among mobile robots. A flocking control protocol which is based on the
information of neighbor mobile robots is constructed. The theoretical analysis
is conducted with the help of a Lyapunov-like function and graph theory.
Simulation results are shown to demonstrate the efficacy of the proposed
distributed flocking control scheme
The impact of culture on advertising appeals in mobile phone industry: a study of social video advertising in UK, Brasil, India and Poland
International social media advertising research in emerging markets is called for investigation. Thus, this study explores the impact of culture on advertising appeals in mobile phone industry via social video channel in UK, Poland, Brazil and India. Hofstede model (1980, 2001), Pollay model (1983) and social video users & gratifications are used as primary theoretical frameworks. The exploratory research approach is utilized. More particularly, semiology and content analysis research methodology are employed. The empirical data is based on advertisements of the main channels of Samsung and Nokia in YouTube.
The findings indicate that culture does influence on advertising appeals in social video channels. However, the results do not support Hofstede cultural framework assumptions. It shows more correlation with Okazaki’s view about desired and desirable value paradox. This requires further research. Moreover, social video channel plays significant role because the most frequent appeals in four countries are linked with this channel.
The study also sheds light to managerial implications for international social video advertising. It suggests that advertiser should establish contingency between emotion and brands. Advertisers should highlight emotional appeals but also nourish brand memory. Information is integrated to describe product functions and benefits in mobile phone industry and in emerging markets where consumers are still unfamiliar with new mobile phone characteristics and advantages.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format
EAGLE—A Scalable Query Processing Engine for Linked Sensor Data
Recently, many approaches have been proposed to manage sensor data using semantic web technologies for effective heterogeneous data integration. However, our empirical observations revealed that these solutions primarily focused on semantic relationships and unfortunately paid less attention to spatio–temporal correlations. Most semantic approaches do not have spatio–temporal support. Some of them have attempted to provide full spatio–temporal support, but have poor performance for complex spatio–temporal aggregate queries. In addition, while the volume of sensor data is rapidly growing, the challenge of querying and managing the massive volumes of data generated by sensing devices still remains unsolved. In this article, we introduce EAGLE, a spatio–temporal query engine for querying sensor data based on the linked data model. The ultimate goal of EAGLE is to provide an elastic and scalable system which allows fast searching and analysis with respect to the relationships of space, time and semantics in sensor data. We also extend SPARQL with a set of new query operators in order to support spatio–temporal computing in the linked sensor data context.EC/H2020/732679/EU/ACTivating InnoVative IoT smart living environments for AGEing well/ACTIVAGEEC/H2020/661180/EU/A Scalable and Elastic Platform for Near-Realtime Analytics for The Graph of Everything/SMARTE
Thermoresistance of p-Type 4H–SiC Integrated MEMS Devices for High-Temperature Sensing
There is an increasing demand for the development and integration of multifunctional sensing modules into power electronic devices that can operate in high temperature environments. Here, the authors demonstrate the tunable thermoresistance of p‐type 4H–SiC for a wide temperature range from the room temperature to above 800 K with integrated flow sensing functionality into a single power electronic chip. The electrical resistance of p‐type 4H–SiC is found to exponentially decrease with increasing temperature to a threshold temperature of 536 K. The temperature coefficient of resistance (TCR) shows a large and negative value from −2100 to −7600 ppm K−1, corresponding to a thermal index of 625 K. From the threshold temperature of 536–846 K, the electrical resistance shows excellent linearity with a positive TCR value of 900 ppm K−1. The authors successfully demonstrate the integration of p–4H–SiC flow sensing functionality with a high sensitivity of 1.035 μA(m s−1)−0.5 mW−1. These insights in the electrical transport of p–4H–SiC aid to improve the performance of p–4H–SiC integrated temperature and flow sensing systems, as well as the design consideration and integration of thermal sensors into 4H–SiC power electronic systems operating at high temperatures of up to 846 K
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