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141.
Tomás Sánchez López Damith C. Ranasinghe Mark Harrison Duncan McFarlane 《Personal and Ubiquitous Computing》2012,16(3):291-308
The Internet of Things (IoT) concept is being widely presented as the next revolution toward massively distributed information,
where any real-world object can automatically participate in the Internet and thus be globally discovered and queried. Despite
the consensus on the great potential of the concept and the significant progress in a number of enabling technologies, there
is a general lack of an integrated vision on how to realize it. This paper examines the technologies that will be fundamental
for realizing the IoT and proposes an architecture that integrates them into a single platform. The architecture introduces
the use of the Smart Object framework to encapsulate radio-frequency identification (RFID), sensor technologies, embedded
object logic, object ad-hoc networking, and Internet-based information infrastructure. We evaluate the architecture against
a number of energy-based performance measures, and also show that it outperforms existing industry standards in metrics such
as network throughput, delivery ratio, or routing distance. Finally, we demonstrate the feasibility and flexibility of the
architecture by detailing an implementation using Wireless Sensor Networks and Web Services, and describe a prototype for
the real-time monitoring of goods flowing through a supply chain. 相似文献
142.
A Gaussian sum filter (GSF) with component extended Kalman filters (EKF) is proposed as an approach to localizing an autonomous vehicle in an urban environment with limited GPS availability. The GSF uses vehicle‐relative vision‐based measurements of known map features coupled with inertial navigation solutions to accomplish localization in the absence of GPS. The vision‐based measurements have multimodal measurement likelihood functions that are well represented as weighted sums of Gaussian densities. The GSF is used because of its ability to represent the posterior distribution of the vehicle pose with better efficiency (fewer terms, less computational complexity) than a corresponding bootstrap particle filter with various numbers of particles because of the interaction with measurement hypothesis tests. The expectation‐maximization algorithm is used off line to determine the representational efficiency of the particle filter in terms of an effective number of Gaussian densities. In comparison, the GSF, which uses an iterative condensation procedure after each iteration of the filter to maintain real‐time capabilities, is shown through a series of in‐depth empirical studies to more accurately maintain a representation of the posterior distribution than the particle filter using 37 min of recorded data from Cornell University's autonomous vehicle driven in an urban environment, including a 32 min GPS blackout. © 2012 Wiley Periodicals, Inc. 相似文献
143.
The focus of this article is on the creation of a collection of sentences manually annotated with respect to their sentence
structure. We show that the concept of linear segments—linguistically motivated units, which may be easily detected automatically—serves
as a good basis for the identification of clauses in Czech. The segment annotation captures such relationships as subordination,
coordination, apposition and parenthesis; based on segmentation charts, individual clauses forming a complex sentence are
identified. The annotation of a sentence structure enriches a dependency-based framework with explicit syntactic information
on relations among complex units like clauses. We have gathered a collection of 3,444 sentences from the Prague Dependency
Treebank, which were annotated with respect to their sentence structure (these sentences comprise 10,746 segments forming
6,341 clauses). The main purpose of the project is to gain a development data—promising results for Czech NLP tools (as a
dependency parser or a machine translation system for related languages) that adopt an idea of clause segmentation have been
already reported. The collection of sentences with annotated sentence structure provides the possibility of further improvement
of such tools. 相似文献
144.
The dynamic capacity theorem characterizes the reliable communication rates of a quantum channel when combined with the noiseless resources of classical communication, quantum communication, and entanglement. In prior work, we proved the converse part of this theorem by making contact with many previous results in the quantum Shannon theory literature. In this work, we prove the theorem with an ??ab initio?? approach, using only the most basic tools in the quantum information theorist??s toolkit: the Alicki-Fannes?? inequality, the chain rule for quantum mutual information, elementary properties of quantum entropy, and the quantum data processing inequality. The result is a simplified proof of the theorem that should be more accessible to those unfamiliar with the quantum Shannon theory literature. We also demonstrate that the ??quantum dynamic capacity formula?? characterizes the Pareto optimal trade-off surface for the full dynamic capacity region. Additivity of this formula reduces the computation of the trade-off surface to a tractable, textbook problem in Pareto trade-off analysis, and we prove that its additivity holds for the quantum Hadamard channels and the quantum erasure channel. We then determine exact expressions for and plot the dynamic capacity region of the quantum dephasing channel, an example from the Hadamard class, and the quantum erasure channel. 相似文献
145.
A rapidly solidified (Co, Fe)3O4 spinel was formed in a cobalt-iron-phosphate glass matrix by gas atomization of melts of composition 37.5% mol % CoO, 37.5%Fe2O3, 25% P2O5; and 40% CoO, 40% Fe2O3, 20% P2O5, and the material has been characterized using size analysis, X-ray diffraction, Mössbauer spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy.In the 20 mol % P2O5 composition, atomized powder 50–100m in diameter contained 33 wt % (Co, Fe)3O4. The ferrite crystallized as randomly oriented, faceted dendrites parallel to 100, and the growth was apparently diffusion controlled. Unlike the ferrite, where iron is in both tetrahedral and octahedral coordination, the iron in the glassy matrix was predominantly in distorted octahedral coordination. Overall particle size distributions were broad (15–700m), with 50 wt % smaller than 200m. The maximum in the size distribution shifted from 150 to 80m on increasing the atomizing pressure from 7 to 20 bar (100 to 300 psi). Calculations have shown that the cooling rates obtained with oxide melts vary strongly with droplet size, and less strongly with melt temperature. 相似文献
146.
Summary The desire to extend the applicability of the relational model beyond traditional data-processing applications has stimulated interest in nested or non-first normal form relations in which the attributes of a relation can take on values which are sets or even relations themselves. In this paper, we study the role of null values in the nested relational model using an open world assumption. We extend the traditional theory and study the properties of extended operators for nested relations containing nulls. The no-information, unknown, and non-existent interpretation of nulls are discussed and the meaning of empty set is clarified. Finally, contrary to several previous results, we determine that the traditional axiomatization of functional and multivalued dependencies is valid in the presence of nulls.Currently with the Air Force Institute of Technology, AFIT/ENG, Wright-Patterson AFB, OH 45433, USAResearch partially supported by an IBM Faculty Development A ward and NSF grant DCR-8507224 相似文献
147.
Stainless steel fibres in ABS plastic form a composite with an anisotropic resistivity. Samples are rectangular shapes with uniform thickness. By assuming two principal resistivities and by using van der Pauw's technique, we find
2 =
x
y
. For rectangular samples, field theory determines
y
/
x
and hence fibre direction. Results for three sample geometries agree with the theoretical predictions of the fibre patterns and with X-ray data. Samples formed by a centre-sprue feed are the best for fabricating large, uniform samples, while samples with a large length-to-width ratio have the most uniform metal density and fibre orientation. Resistivity was also measured by the more-common two-probe technique. Results correlate well to van der Pauw data, with 95% confidence. 相似文献
148.
M. Z. Harford Mark Rubinstein A. K. Singh A. E. Edelstein S. A. Wolf 《Journal of Superconductivity》1988,1(4):407-415
We have investigated the temperature dependence of the electrical transport and the thermogravimetric properties, from -200°C to +1000, of the Bi-Sr-Ca-Cu-O high-temperature superconductor. We conclude that this system has a cooperative, simultaneous-melting/oxygen desorption/metal-insulator transition that occurs near 900°C. We speculate on its nature and on its relationship to phenomena found in other high-T
c superconductors. 相似文献
149.
Mark J. Bennett 《Journal of Systems Integration》1992,2(1):53-66
In this paper we discuss an approach to organizing the integration of 110,000 lines of C, SQL, Assembler, and microcode distributed over a network of 36 processors of four types so that it could be accomplished in six months. The software runs on a test system architecture consisting of a LAN-based workstation group and a set of VME-based embedded processors. By using structured methodology, parallelism in the integration process was achieved. The necessary stub tools were identified and developed before integration began. The principles followed and experiences of integrating the system are discussed. 相似文献
150.
A boundary element method is developed for the analysis of fractures in two-dimensional solids. The solids are assumed to be linearly elastic and isotropic, and both bounded and unbounded domains are treated. The development of the boundary integral equations exploits (as usual) Somigliana's identity, but a special manipulation is carried out to regularize certain integrals associated with the crack line. The resulting integral equations consist of the conventional ordinary boundary terms and two additional terms which can be identified as a distribution of concentrated forces and a distribution of dislocations along each crack line. The strategy for establishing the integral equations is first outlined in terms of real variables, after which complex variable techniques are adopted for the detailed development. In the numerical implementation of the formulation, the ordinary boundary integrals are treated with standard boundary element techniques, while a novel numerical procedure is developed to treat the crack line integrals. The resulting numerical procedure is used to solve several sample problems for both embedded and surface-breaking cracks, and it is shown that the technique is both accurate and efficient. The utility of the method for simulating curvilinear crack propagation is also demonstrated. 相似文献