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1.
2.
The activation of propane using zeolite H-Y and Ga3+ exchanged zeolite Y indicates that in the presence of Ga3+ the mechanism of propane activation is changed from a cracking pathway to a dehydrogenation pathway. The presence of both Ga3+ and H+ are required to achieve this effect. 相似文献
3.
L. B. Gavin A. S. Mul'gi V. V. Shor 《Journal of Engineering Physics and Thermophysics》1986,50(5):505-511
Temperature and momentum distributions of the carrier phase are determined experimentally and compared to results of numerical calculations using the (k–) model.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 5, pp. 735–743, May, 1986. 相似文献
4.
The concentration fields of disperse impurity are calculated on the basis of a k- model of turbulence in a wide range of Stokes numbers.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 4, pp. 548–555, October, 1985. 相似文献
5.
Methanesulphenyl chloride and n-butanesulphenyl chloride add readily across the double bonds in cis-1,4-polybutadiene. The addition is highly regioselective so that long sequences of saturated units are formed. The products are very unstable, evolving hydrogen chloride on standing, but can be stabilized by replacing the labile chlorine atom with other nucleophiles in a phase transfer catalysed reaction. 相似文献
6.
An Example-based Procedural System for Element Arrangement 总被引:2,自引:0,他引:2
We present a method for synthesizing two dimensional (2D) element arrangements from an example. The main idea is to combine texture synthesis techniques based‐on a local neighborhood comparison and procedural modeling systems based‐on local growth. Given a user‐specified reference pattern, our system analyzes neigh‐borhood information of each element by constructing connectivity. Our synthesis process starts with a single seed and progressively places elements one by one by searching a reference element which has local features that are the most similar to the target place of the synthesized pattern. To support creative design activities, we introduce three types of interaction for controlling global features of the resulting pattern, namely a spray tool, a flow field tool, and a boundary tool. We also introduce a global optimization process that helps to avoid local error concentrations. We illustrate the feasibility of our method by creating several types of 2D patterns. 相似文献
7.
Specification of communicating processes: temporal logic versus refusals-based refinement 总被引:1,自引:1,他引:0
Gavin Lowe 《Formal Aspects of Computing》2008,20(3):277-294
In this paper we consider the relationship between refinement-oriented specification and specifications using a temporal logic.
We investigate the extent to which one can check whether a program in a process algebra, such as Communicating Sequential
Processes (CSP), satisfies a temporal logic specification using a refinement-based model checker, such as FDR. We consider
what atomic formulae are appropriate in a temporal logic for specifying communicating processes, in particular where one wants
to talk about the availability of events. We then show that, perhaps surprisingly, the standard stable failures model is not
adequate for capturing specifications in such a logic: instead the refusal traces model must be used. We formalise the logic
by giving it a semantics in this model. We show that the temporal operators eventually and until, and negation, cannot, in general, be tested for via simple refinement checks. For the remaining fragment of the logic, we
present a translation into simple refinement checks. Finally, we show that refusal traces equivalence is characterised by
a slightly augmented version of that fragment.
M. J. Butler 相似文献
8.
Sayyed Mohamad Azimi Gavin Nixon Jeremy Ahern Wamadewa Balachandran 《Microfluidics and nanofluidics》2011,11(2):157-165
This article introduces a novel magnetic bead-based DNA extraction and purification device using active magnetic mixing approach.
Mixing and separation steps are performed using functionalised superparamagnetic beads suspended in cell lysis buffer in a
circular chamber that is sandwiched between two external magnetic coils. Non-uniform nature of magnetic field causes temporal
and spatial distribution of beads within the chamber. This process efficiently mixes the lysis buffer and whole blood in order
to extract DNA from target cells. Functionalized surface of the magnetic beads then attract the exposed DNA molecules. Finally,
DNA-attached magnetic beads are attracted to the bottom of the chamber by activating the bottom magnetic coil. DNA molecules
are extracted from magnetic beads by washing and re-suspension processes. In this study, a circular PMMA microchamber, 25 μL
in volume, 500 μm in depth and 8 mm in diameter was fabricated to purify DNA from spiked bacterial cell cultures into the
whole blood sample using Promega Magazorb DNA extraction kit. The lysis efficiency was evaluated using a panel of Gram-positive
(Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial cells cultures into the blood sample to achieve approximately 100,000 copy levels inside the chip. Manufacturer’s
standard extraction protocol was modified to a more simplified process suitable for chip-based extraction. The lysis step
was performed using 5 min incubation at 56 °C followed by 5 min incubation at room temperature for binding process. Temperature
rise was generated and maintained by the same external magnetic coils used for active mixing. The yield/purity and recovery
levels of the extracted DNA were evaluated using quantitative UV spectrophotometer and real-time PCR assay, respectively.
Real-time PCR results indicated efficient chip-based bacterial DNA extraction using modified extraction protocol comparable
to the standard bench-top extraction process. 相似文献
9.
Gavin Paul Stephen Webb Dikai Liu Gamini Dissanayake 《Robotics and Autonomous Systems》2011,59(7-8):543-554
This paper presents a system for Autonomous eXploration to Build A Map (AXBAM) of an unknown, 3D complex steel bridge structure using a 6 degree-of-freedom anthropomorphic robot manipulator instrumented with a laser range scanner. The proposed algorithm considers the trade-off between the predicted environment information gain available from a sensing viewpoint and the manipulator joint angle changes required to position a sensor at that viewpoint, and then obtains collision-free paths through safe, previously explored regions. Information gathered from multiple viewpoints is fused to achieve a detailed 3D map. Experimental results show that the AXBAM system explores and builds quality maps of complex unknown regions in a consistent and timely manner. 相似文献
10.
Formal approaches to the design of interactive systems rely on reasoning about properties of the system at a very high level
of abstraction. Specifications to support such an approach typically provide little scope for reasoning about presentations
and the representation of information in the presentation. In contrast, psychological theories such as distributed cognition place a strong emphasis
on the role of representations, and their perception by the user, in the cognitive process. However, the post-hoc techniques
for the observation and analysis of existing systems which have developed out of the theory do not help us in addressing such
issues at the design stage. Mn this paper we show how a formalisation can be used to investigate the representational aspects
of an interface. Our goal is to provide a framework to help identify and resolve potential problems with the representation
of information, and to support understanding of representational issues in design. We present a model for linking properties
at the abstract and perceptual levels, and illustrate its use in a case study of a ight deck instrument. There is a widespread
consensus that proper tool support is a prerequisite for the adoption of formal techniques, but the use of such tools can
have a profound effect on the process itself. In order to explore this issue, we apply a higher-order logic theorem prover
to the analysis.
Received May 1999 / Accepted in revised form July 2000 相似文献