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排序方式: 共有1103条查询结果,搜索用时 15 毫秒
1.
The architects and builders in the past lacked our knowledge concerning fluid dynamics, but they exhibited a deep rooted ability to observe and reflect - thus, different cultures have developed by trial and error. The authors have produced a stimulating analysis which couples the science of fluid dynamics and a sensitive understanding of past cultures. The paper is recommended reading. 相似文献
2.
Scene Graph and Frame Update Algorithms for Smooth and Scalable 3D Visualization of Simulated Construction Operations 总被引:1,自引:0,他引:1
Vineet R. Kamat & Julio C. Martinez 《Computer-Aided Civil and Infrastructure Engineering》2002,17(4):228-245
One of the prime reasons inhibiting the widespread use of discrete-event simulation in construction planning is the absence of appropriate visual communication tools. Visualizing modeled operations in 3D is arguably the best form of communicating the logic and the inner working of simulation models and can be of immense help in establishing the credibility of analyses. New software development technologies emerge at incredible rates that allow engineers and scientists to create novel, domain-specific applications. The authors capitalized on a computer graphics technology based on the concept of the scene graph to design and implement a general-purpose 3D visualization system that is simulation and CAD-software independent. This system, the Dynamic Construction Visualizer, enables realistic visualization of modeled construction operations and the resulting products and can be used in conjunction with a wide variety of simulation tools. This paper describes the scene graph architecture and the frame updating algorithms used in designing the Dynamic Construction Visualizer. 相似文献
3.
Pena Julio Nápoles Gonzalo Salgueiro Yamisleydi 《Artificial Intelligence Review》2021,54(5):3817-3847
Artificial Intelligence Review - Attribute weighting is a task of paramount relevance in multi-attribute decision-making (MADM). Over the years, different approaches have been developed to face... 相似文献
4.
Julio J. Garcia‐Sabater Juan A. Marin‐Garcia M. Rosario Perello‐Marin 《人机工程学与制造业中的人性因素》2012,22(2):99-112
The purpose of this article is to present an evolutionary model of the enablers and inhibitors affecting the implementation and sustainability of continuous improvement. With this aim, a qualitative study using the grounded theory was carried out. Interviews were conducted with managers responsible for continuous improvement in first‐tier suppliers in the automotive sector. As a result, two existing lines of research in the continuous improvement literature are synthesized: on one hand, the literature concerning the enablers and barriers associated with continuous improvement sustainability; and on the other, the literature concerning the evolutionary model. © 2011 Wiley Periodicals, Inc. 相似文献
5.
Jorge Blasco Julio Cesar Hernandez-Castro 《Journal of Network and Computer Applications》2012,35(1):491-501
Steganographic techniques allow users to covertly transmit information, hiding the existence of the communication itself. These can be used in several scenarios ranging from evading censorship to discreetly extracting sensitive information from an organization. In this paper, we consider the problem of using steganography through a widely used network protocol (i.e. HTTP). We analyze the steganographic possibilities of HTTP, and propose an active warden model to hinder the usage of covert communication channels. Our framework is meant to be useful in many scenarios. It could be employed to ensure that malicious insiders are not able to use steganography to leak information outside an organization. Furthermore, our model could be used by web servers administrators to ensure that their services are not being abused, for example, as anonymous steganographic mailboxes. Our experiments show that steganographic contents can be successfully eliminated, but that dealing with high payload carriers such as large images may introduce notable delays in the communication process. 相似文献
6.
The equation of state model developed by Lacombe and Sanchez (J Phys Chem 1976, 80, 2352) is used in the form proposed later by Sanchez and Stone (Polymer Blends, Vol. 1: Formulation, 2000; Chapter 2) to correlate experimental vapor‐liquid equilibrium (VLE) data for the three binaries and the ternary systems. Experimental data from the binary systems carbon dioxide‐isopropyl alcohol (CO2‐IPrOH), isopropyl alcohol‐polystyrene (IPrOH‐PS), and carbon dioxide‐polystyrene (CO2‐PS) are used to calculate VLE properties for the ternary system CO2‐IPrOH‐PS. Two‐dimensional VLE‐phase diagrams were calculated and used to describe from a thermodynamic point of view the pressure, volume, and temperature values that characterize a thermoplastic foam evolution process, from the extruder to the foaming die. For different initial mixture CO2 + IPrOH concentrations, pressure reduction produces liquid foaming until the vitrification curve arrests the final foam volume expansion. The dependence of the vitreous transition with the system CO2 + IPrOH concentration while foaming is represented by the Chow (Macromolecules 1980, 13, 362) equation. The calculation procedure is proposed as a design tool to reduce the amount of experimental data usually needed as a requirement previous to the design stage. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2663–2671, 2007 相似文献
7.
Binary and ternary experimental cloud‐point curves (CPCs) for systems formulated with a low molar mass synthesized divinylester (DVE) resin, styrene (St), and poly(methyl methacrylate) (PMMA) were determined. The CPCs results were analyzed with the Flory–Huggins (F‐H) thermodynamic model taking into account the polydispersity of the DVE and PMMA components, to calculate the different binary interaction parameters and their temperature dependences. The St‐DVE system is miscible in all the composition range and down to the crystallization temperature of the St; therefore, the interaction parameter expression reported for a higher molar mass DVE was adapted. The interaction parameters obtained were used to calculate the phase diagrams of the St‐PMMA and the DVE‐PMMA binary systems and that of the St‐DVE‐PMMA ternary system at three different temperatures. Quasiternary phase diagrams show liquid–liquid partial miscibility of the St‐PMMA and DVE‐PMMA pairs. At room temperature, the St‐DVE‐PMMA system is miscible at all compositions. Final morphologies of PMMA‐modified cured St‐DVE materials were generated by polymerization‐induced phase separation (PIPS) mechanism from initial homogeneous mixtures. SEM and TEM micrographs were obtained to analyze the generated final morphologies, which showed a direct correlation with the initial miscibility of the system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4539–4549, 2006 相似文献
8.
David F. Barrero Julio César Hernández‐Castro Pedro Peris‐Lopez David Camacho María D. R‐Moreno 《Expert Systems》2014,31(1):9-19
Radio frequency identification (RFID) is a powerful technology that enables wireless information storage and control in an economical way. These properties have generated a wide range of applications in different areas. Due to economic and technological constrains, RFID devices are seriously limited, having small or even tiny computational capabilities. This issue is particularly challenging from the security point of view. Security protocols in RFID environments have to deal with strong computational limitations, and classical protocols cannot be used in this context. There have been several attempts to overcome these limitations in the form of new lightweight security protocols designed to be used in very constrained (sometimes called ultra‐lightweight) RFID environments. One of these proposals is the David–Prasad ultra‐lightweight authentication protocol. This protocol was successfully attacked using a cryptanalysis technique named Tango attack. The capacity of the attack depends on a set of boolean approximations. In this paper, we present an enhanced version of the Tango attack, named Genetic Tango attack, that uses Genetic Programming to design those approximations, easing the generation of automatic cryptanalysis and improving its power compared to a manually designed attack. Experimental results are given to illustrate the effectiveness of this new attack. 相似文献
9.
Two samples of poly(diethoxyphosphazene) (PDEP) having very different molecular weights have been studied by viscometry and size exclusion chromatography in THF solution. The results obtained, together with light scattering data of these samples, allow the calculation of the Mark-Houwink constants a=0.65 and K=2.5 10-4 in THF at 25°C. The method of calculation employed takes into account the great polydispersity of the samples. The characteristic ratio of the unperturbed dimensions was also calculated giving Cn = r2o/n2 18, a value slightly higher than those previously reported for poly(dihexoxyphosphazene), Cn13 and poly (dichlorophosphazene), Cn13.5. 相似文献
10.
Julio Cesar dos Reis Rodrigo Bonacin M. Cecília C. Baranauskas 《Universal Access in the Information Society》2014,13(2):125-145
Social network services (SNSs) have brought new possibilities and challenges to the design of software environments that respect people’s cultural differences. These systems may represent an opportunity for social and digital inclusion. However, search mechanisms in these systems impose serious barriers for people in the process of acquiring digital literacy. One of the barriers is the difficulty of using the adequate terms/keywords to perform content searches. This paper presents an approach to allow ordinary, non-technology proficient people to access the content of a network through the use of search parameters that make sense to them. The proposal is grounded on Semantic Web technologies (Web ontology) combined with Organizational Semiotics concepts and methods to identify the users’ profile and language. A case study was conducted with the search mechanism integrated into a SNS, and a preliminary evaluation reveals the advantages and drawbacks of the approach. 相似文献