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1.
《Computer》1980,13(8):16-21
Several tools–originally intended for developing "classical" compilers–have also proved useful in a variety of application programs. 相似文献
2.
John Dinsmore 《New Generation Computing》1991,9(1):39-68
A logic-based system of knowledge representation for natural language discourse has three primary advantages:
On the other hand, a standard logic-based system has the following disadvantages:
相似文献
– | • It has adequate expressive power, |
– | • it has a well-defined semantics, and |
– | • it uses simple, sound, general rules of inference. |
– | • It supports only an exceedingly complex mapping from surface discourse sentences to internal representations, and |
– | • reasoning about the content of semantically complex discourses is difficult because of the incommodious complexity of the internalized formulas. |
3.
This paper proposes a new multiparameter method for analysis and selection of motion estimation algorithms for video compression.
We present motion estimation algorithms, results of computer simulations and illustrate the analysis with tables, PSNR and
performance plots. Numerous algorithms and tests for analysis of algorithm performance for video compression have recently
been suggested, which has resulted in a need for effective evaluation methods. A highly qualified expert is also needed to
evaluate the test results. The more input parameters used the more complex and subjective the evaluation will be. Our multiparameter
method for algorithm analysis and selection eliminates subjectivity and provides a qualitative and quantitative evaluation
of the tested algorithms for any number of algorithms and parameters. We propose two new methods of evaluation: (1) a quality
method—a graphic method using the Pareto approach, and (2) a quantity method which obtains an integrated parameter composed
of numerous evaluation parameters. In addition, we evaluate various motion estimation algorithms accordingly to two different
implementation strategies: (a) using a software video encoder that depends on available processing resources using a computational
complexity–rate–distortion (C–R–D) evaluation framework and (b) using a power-limited video encoder implemented on mobile or handheld computing platform by
using energy–rate–distortion (E–R–D) behavior.
相似文献
Ofer HadarEmail: |
4.
A. S. Garbuz 《Cybernetics and Systems Analysis》1997,33(4):581-588
Conclusion We have provided a theoretical and methodological justification of complete construction of a universal formalized language
of knowledge. We have proved the following:
Deceased.
Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 154–162, July–August, 1997. 相似文献
– | the base term classification ensures unambiguous and deep indexation of documents; |
– | the fixed sentence syntax makes it possible to standardize information-retrieval languages and automatic translation between languages; |
– | the fixed message semantics provides the following opportunities: measuring the semantic information; rating the intensification of intellectual effort; eliminating unjustified duplication of research and publication; providing the user with timely necessary information in a form suitable for direct processing and use; organizing a national cost-efficient communication technology; solving linguistic problems of artificial intelligence and informatization of society; creating a reliable structural foundation for the development of a common unambiguous language for the entire humanity. |
5.
To determine the maximum separation between events for nonrepetitive systems with max and linear constraints, there are the
“iterative tightening from above” (ITA) approach and the “iterative tightening from below” (ITB) approach. Since such systems
can be formulated as systems constrained by min–max inequalities, this paper gives an algorithm named MMIMaxSep for solving min–max inequalities. The algorithm is a generalization and a mathematically elegant reformulation of Yen et
al.’s MaxSeparation algorithm which uses the ITB approach. Our numerical experiments indicate that MMIMaxSep is very efficient. Moreover, MMIMaxSep has a unique advantage of being able to directly handle tree-represented min–max functions, and its complexity is closely
related to the complexity of computing cycle time of min–max functions.
相似文献
Yiping ChengEmail: |
6.
We study the general (composite) Newton–Cotes rules for the computation of Hadamard finite-part integral on a circle with
the hypersingular kernel and focus on their pointwise superconvergence phenomenon, i.e., when the singular point coincides with some a priori known
point, the convergence rate is higher than what is globally possible. We show that the superconvergence rate of the (composite)
Newton–Cotes rules occurs at the zeros of a special function and prove the existence of the superconvergence points. The relation between and defined in Wu and Sun (Numer Math 109:143–165, 2008) is established, and the efficient calculation of Cotes coefficients
is also discussed. Several numerical examples are provided to validate the theoretical analysis.
相似文献
7.
Dipl.-Wirtsch.-Ing Michael Klafft Dr. rer. pol. Sarah Spiekermann 《WIRTSCHAFTSINFORMATIK》2006,48(1):36-45
Web-based bid invitation platforms and reverse auctions are increasingly used by consumers for the procurement of goods and
services. An empirical examination shows that with B-2-C these procurement methods generate considerable benefits for the
consumer:
相似文献
– | ⊎ Reverse auctions and bid invitation platforms generate high consumer surplus in the procurement of general and crafts services. |
– | ⊎ The level of this consumer surplus is affected by the number of bidders. The duration of the auction and the starting price are less important. |
– | ⊎ In the painting business prices are considerably lower than with traditional procurement channels. |
– | ⊎ On bid invitation platforms, in most cases (> 55%) the bids with the lowest price are chosen. |
8.
We couple pseudo-particle modeling (PPM, Ge and Li in Chem Eng Sci 58(8):1565–1585, 2003), a variant of hard-particle molecular dynamics, with standard soft-particle molecular dynamics (MD) to study an idealized
gas–liquid flow in nano-channels. The coupling helps to keep sharp contrast between gas and liquid behaviors and the simulations
conducted provide a reference frame for exploring more complex and realistic gas–liquid nano-flows. The qualitative nature
and general flow patterns of the flow under such extreme conditions are found to be consistent with its macro-scale counterpart.
相似文献
Wei GeEmail: |
9.
Krzysztof Kozłowski Przemysław Herman 《Journal of Intelligent and Robotic Systems》2008,53(3):205-221
In this paper we present new control algorithms for robots with dynamics described in terms of quasi-velocities (Kozłowski,
Identification of articulated body inertias and decoupled control of robots in terms of quasi-coordinates. In: Proc. of the
1996 IEEE International Conference on Robotics and Automation, pp. 317–322. IEEE, Piscataway, 1996a; Zeitschrift für Angewandte Mathematik und Mechanik 76(S3):479–480, 1996c; Robot control algorithms in terms of quasi-coordinates. In: Proc. of the 34 Conference on Decision and Control, pp. 3020–3025,
Kobe, 11–13 December 1996, 1996d). The equations of motion are written using spatial quantities such as spatial velocities, accelerations, forces, and articulated
body inertia matrices (Kozłowski, Standard and diagonalized Lagrangian dynamics: a comparison. In: Proc. of the 1995 IEEE
Int. Conf. on Robotics and Automation, pp. 2823–2828. IEEE, Piscataway, 1995b; Rodriguez and Kreutz, Recursive Mass Matrix Factorization and Inversion, An Operator Approach to Open- and Closed-Chain
Multibody Dynamics, pp. 88–11. JPL, Dartmouth, 1998). The forward dynamics algorithms incorporate new control laws in terms of normalized quasi-velocities. Two cases are considered:
end point trajectory tracking and trajectory tracking algorithm, in general. It is shown that by properly choosing the Lyapunov
function candidate a dynamic system with appropriate feedback can be made asymptotically stable and follows the desired trajectory
in the task space. All of the control laws have a new architecture in the sense that they are derived, in the so-called quasi-velocity
and quasi-force space, and at any instant of time generalized positions and forces can be recovered from order recursions, where denotes the number of degrees of freedom of the manipulator. This paper also contains the proposition of a sliding mode control,
originally introduced by Slotine and Li (Int J Rob Res 6(3):49–59, 1987), which has been extended to the sliding mode control in the quasi-velocity and quasi-force space. Experimental results illustrate
behavior of the new control schemes and show the potential of the approach in the quasi-velocity and quasi-force space.
Authors are with Chair of Control and Systems Engineering. 相似文献
10.
We study the properties of the reference mapping for quadrilateral and hexahedral finite elements. We consider multilevel
adaptive grids with possibly hanging nodes which are typically generated by adaptive refinement starting from a regular coarse
grid. It turns out that for such grids the reference mapping behaves – up to a perturbation depending on the mesh size – like
an affine mapping. As an application, we prove optimal estimates of the interpolation error for discontinuous mapped
-elements on quadrilateral and hexahedral grids. 相似文献
11.
R. V. Skuratovsky 《Cybernetics and Systems Analysis》2009,45(1):25-37
The corepresentation of a Sylow p-subgroup of a symmetric group in the form of generating relations is investigated, and a
Sylow subgroup of a group , i.e., an n-fold wreath product of regular cyclic groups of prime order, that is isomorphic to the group of automorphisms
of a spherically homogeneous root tree is also studied.
Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 27–41, January–February 2009. 相似文献
12.
Distributed authorization is an essential issue in computer security. Recent research shows that trust management is a promising
approach for the authorization in distributed environments. There are two key issues for a trust management system: how to
design an expressive high-level policy language and how to solve the compliance-checking problem (Blaze et al. in Proceedings
of the Symposium on Security and Privacy, pp. 164–173, 1996; Proceedings of 2nd International Conference on Financial Cryptography
(FC’98). LNCS, vol.1465, pp. 254–274, 1998), where ordinary logic programming has been used to formalize various distributed
authorization policies (Li et al. in Proceedings of the 2002 IEEE Symposium on Security and Privacy, pp. 114–130, 2002; ACM
Trans. Inf. Syst. Secur. (TISSEC) 6(1):128–171, 2003). In this paper, we employ Answer Set Programming to deal with many complex
issues associated with the distributed authorization along the trust management approach. In particular, we propose a formal
authorization language providing its semantics through Answer Set Programming. Using language , we cannot only express nonmonotonic delegation policies which have not been considered in previous approaches, but also
represent the delegation with depth, separation of duty, and positive and negative authorizations. We also investigate basic
computational properties related to our approach. Through two case studies. we further illustrate the application of our approach
in distributed environments. 相似文献
13.
Modulare hierarchische Modellierung als Grundlage der Software- und Systementwicklung 总被引:5,自引:4,他引:1
Zusammenfassung Die Entwicklung komplexer eingebetteter Softwaresysteme, wie sie heute beispielsweise in Telekommunikationssystemen, Fahr-
oder Flugzeugen oder mit der Steuersoftware von Automatisierungssystemen im Einsatz sind, erfordert ein strukturiertes, modulares
Vorgehen und angemessene Techniken zur pr?zisen Beschreibung von Anforderungen, der Architektur des Systems mit ihren Komponenten,
der Schnittstellen zur Systemumgebung und zwischen den internen Komponenten, der Wechselwirkung zwischen gesteuertem und steuerndem
Teilsystem und schlie?lich der Implementierung. Mit dem frühzeitigen und durchg?ngigen Einsatz geeigneter Modelle (Stichwort
UML (,,Unified Modeling Language“) und MDA (,,Model Driven Architecture“)) werden gro?e Hoffnungen verbunden, die Entwicklungsaufgaben
beherrschbarer zu gestalten.
Dieser Artikel beschreibt die theoretischen Grundlagen für ein konsequent modellbasiertes Vorgehen in Form eines zusammengeh?rigen,
homogenen und dennoch modularen Baukastens von Modellen, der hierfür zwingend erforderlich ist. Besondere Schwerpunkte liegen
hierbei auf den Themen
Dieser Baukasten der Modellierung muss wie bei allen anderen Ingenieursdisziplinen einer durchdachten, in sich stimmigen
logisch-mathematischen Theorie entsprechen. Die hier vorgestellte Theorie besteht aus einem Satz von Notationen und Theoremen,
die eine Basis für wissenschaftlich fundierte, werkzeugunterstützbare Methoden liefern und eine den Anwendungsdom?nen (Stichwort
Dom?nenspezifische Sprachen) pragmatisch angepasste Vorgehensweise bringt.
Für eine wissenschaftlich abgesicherte Methode steht weniger die syntaktische Form der Modellierungssprache als vielmehr die
Modellierungstheorie im Zentrum. Die Repr?sentation von Modellen durch textuelle oder grafische Beschreibungsmittel ist ohne
Zweifel eine wichtige Voraussetzung für den praktischen Einsatz von Modellierungstechniken, muss aber als komfortabler und
grunds?tzlich austauschbarer ,,Syntactic Sugar“ gesehen werden. 相似文献
– | Schnittstellen, |
– | Hierarchische Zerlegung, |
– | Architekturen durch Komposition und Dekomposition, |
– | Abstraktion durch Schichtenbildung, |
– | Realisierung durch Zustandsmaschinen, |
– | Verfeinerung von Hierarchie, Schnittstellen und Verhalten, |
– | Wechsel der Abstraktionsebenen und |
– | Integrierte Sicht auf die gesteuerten und steuernden Teilsysteme. |
14.
The model of the device of reading (visualization) of the hidden magnetic information from the holograms combined with magneto-optical
layer is presented in the article.
Ways of magnetic images formation on the protected documentation and their reading by magneto-optical methods are proposed.
The reading head with the help of magneto-optical meridional Kerr effect allows to observe visually of “effect of blinking”
from the hologram with the hidden magnetic layer. During the work the mathematical analysis magneto-optical Kerr or Faraday
effects was carried out.
The hidden magnetic image based on:
Advantages of the device:
The optical scheme of devices contains a light source, the polarizer, the analyzer, the hologram with magneto-optic layers,
and constant magnet. The hologram is placed between the polarizer and the analyzer.
The text was submitted by the authors in English. 相似文献
– | hard magnetic layer on basis Tb-Fe with perpendicular anisotropy |
– | soft magnetic layers on a basis or permalloy. |
– | non contact reading of the magnetic information |
– | difficulty of recurrence of magnetic images formation technology. |
15.
《Computer》1977,10(5):14-16
Those of us who have worked with stack computers for several years have found an unending source of amazement –and some consternation–in how few computer professionals there are who seem aware that there is an entirely different approach to computer architecture from the familiar von Neumann model. Sometimes when such phrases as "zero-address machine" have dropped from my lips, and I see that the phrase had about as much meaning for the listeners as "zero-bit word" might have, I have wished that knowledge of stack machines were more widely spread. Fortunately Jack Grimes, the technical editor of Computer, had the same desire and suggested that an issue be devoted to the subject. 相似文献
16.
In this paper we apply the direct non-equilibrium molecular dynamics technique to oscillatory flows of fluids in microscopic channels. Initially, we show that the microscopic simulations resemble the macroscopic predictions based on the Navier–Stokes equation very well for large channel width, high density and low temperature. Further simulations for high temperature and low density show that the non-slip boundary condition traditionally used in the macroscopic equation is greatly compromised when the fluid–wall interactions are the same as the fluid–fluid interactions. Simulations of a system with very narrow channel width confirm earlier findings of Poiseuille flow, namely, that the velocity profiles are modulated. We find that these modulations cannot be explained by the local area density model.
相似文献
Jesper S. HansenEmail: |
17.
Particulate fouling studies with alumina dispersions in water were performed in rectangular, silicon microchannels having
hydraulic diameters between 220 and 225 μm with Reynolds numbers of 17–41. Data show for the most part the absence of particle
deposition within the microchannels. The primary reason for this is the relatively high wall shear stress at the microchannel
walls of 2.3–3.5 Pa compared to conventional size passageways. In contrast, the headers for the microchannels are quite susceptible
to particulate fouling under the same conditions. This is because the shear stress in the header region is lower. Proper adjustment
of pH has been identified to effectively mitigate the fouling by controlling the electrostatic forces of repulsion between
particle–particle interactions.
相似文献
Satish G. KandlikarEmail: |
18.
V. I. Sokolov G. V. Mishakov V. Ya. Panchenko M. Yu. Tsvetkov 《Optical Memory & Neural Networks》2007,16(2):67-74
The advances in polymer materials and technologies for telecom applications are reported. The polymers include new highly
halogenated acrylates, which possess absorption losses less than 0.25 dB/cm and refractive indices ranging from 1.3 to 1.5
in the 1.5 μm wavelength region. The halogenated liquid monomers are highly intermixable, photocurable under UV exposure and
exhibit high contrast in polymerization.
The polymer technologies developed at the Institute on Laser and Information Technologies of the Russian Academy of Sciences
(ILIT RAS) include:
The technology for fabricating narrowband Bragg filters on the basis of single-mode polymer waveguides with laser-induced
submicron index gratings is presented in detail. The filters possess narrowband reflection/transmission spectra in the 1.5
μm telecom wavelength region of 0.2–2.7 nm width, nearly rectangular shape of the stopband, reflectivity R > 99% and negligible radiation losses. They can be used for multiplexing/demultiplexing optical signals in high-speed DWDM
fiber networks.
The text was submitted by the authors in English. 相似文献
– | UV contact lithography permitting creation of single-mode polymer waveguides and waveguide arrays |
– | submicron printing for fabricating corrugated waveguides and polymer phase masks |
– | UV laser holography for writing refractive index gratings in polymer materials. |
19.
Deborah L. Harm Laura C. Taylor Millard F. Reschke Jeffrey T. Somers Jacob J. Bloomberg 《The Visual computer》2008,24(11):995-999
Virtual reality environments (VRs) offer unique training opportunities, particularly for training astronauts and preadapting
them to microgravity. The purpose of the current research was to compare disturbances in eye–head–hand (EHH) and eye–head
(GAZE) sensorimotor coordination produced by repeated exposures to VR systems. In general, we observed significant increases
in position errors in manual target acquisition for both horizontal and vertical targets. We also observed a significant decrement
in the ability of subjects to maintain gaze on horizontal eccentric targets immediately after exposure to VR. These preliminary
findings provide some direction for developing training schedules for VR users that facilitate adaptation and support the
idea that VRs may serve as an analog for sensorimotor effects of spaceflight.
相似文献
Deborah L. HarmEmail: |
20.
An earlier time for inserting and/or accelerating tasks 总被引:1,自引:0,他引:1
Qian Guangming 《Real-Time Systems》2009,41(3):181-194
In a periodic real-time system scheduled by the EDF (Earliest Deadline First) algorithm (Liu and Layland, J. ACM 20(1), 40–61,
1973; Barauh, Proc. of the 27th IEEE International Real-Time Systems Symposium, 379–387, 2006; Buttazzo, J. Real-Time Syst. 29(1), 5–26, 2005), when new tasks have to be inserted into the system at run-time and/or current tasks request to increase their rates in
response to internal or external events, the new sum of the utilizations after the insertion and/or acceleration should be
limited, otherwise, one or more current tasks should usually be compressed (their periods being prolonged) in order to avoid
overload. Buttazzo offered a time from which on this kind of adjustment can be done without causing any deadline miss in the
system (Buttazzo et al., IEEE Trans. Comput. 51(3), 289–302, 2002). It is, however, not early enough. In this paper, an earlier time is given and formally proved.
相似文献
Qian GuangmingEmail: |