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81.
We proposed in this study a novel analog complementary metal oxide semiconductor (CMOS) circuit for generating a motion signal
when an object moves, which is a simple structure. The proposed unit circuit was constructed using a previously proposed edge
detection circuit and a novel proposed circuit for generating a motion signal which accepts an edge signal. The part for generating
the motion signal was constructed using six metal oxide semiconductor (MOS) transistors and one capacitor. Results obtained
by the simulation program with integrated circuit emphasis (SPICE) and the measured results of a test circuit constructed
with discrete MOS transistors and the test circuit fabricated with a 1.2 μm CMOS process showed that the proposed unit circuit
can output pulsed current (motion signal) when an object moves on the circuit. It was clarified from the SPICE results that
the two-dimensional network constructed with proposed unit circuits can output motion signals. The size of the novel unit
circuit is expected to be about 110 × 110μm2 obtained by the 1.2 μm CMOS process. It is possible to arrange 90 × 90 unit circuits on a chip which has an area of 1 × 1cm2. The aperture ratio is expected to be about 21%, which is twice as large as that of the previously proposed circuit. An integrated
circuit for image processing in real time can thus be realized by applying the two-dimensional network constructed with the
proposed circuits. 相似文献
82.
We consider the dissipative nonlinear dynamics of a model of interacting atoms driven over a substrate potential. The substrate parameters can be suitably tuned in order to introduce disorder effects starting from two geometrically opposed ideal cases: commensurate and incommensurate interfaces. The role of temperature is also investigated through the inclusion of a stochastic force via a Langevin molecular dynamics approach. Here, we focus on the most interesting tribological case of underdamped sliding dynamics. For different values of the chain stiffness, we evaluate the static friction threshold and consider the depinning transition mechanisms as a function of the applied driving force. As experimentally observed in QCM frictional measurements of adsorbed layers, we find that disorder operates differently depending on the starting geometrical configuration. For commensurate interfaces, randomness lowers considerably the chain depinning threshold. On the contrary, for incommensurate mating contacts, disorder favors static pinning destroying the possible frictionless (superlubric) sliding states. Interestingly, thermal and disorder effects strongly influence also the occurrence of parametric resonances inside the chain, capable of converting the kinetic energy of the center-of-mass motion into internal vibrational excitations. We comment on the nature of the different dynamical states and hysteresis (due to system bi-stability) observed at different increasing and decreasing strengths of the external force. 相似文献
83.
We study the optimal conditions for nanoisland growth in ion beam assisted deposition (IBAD). This situation occurs when adatom islands remain small enough to prevent the onset of three-dimensional growth, while at the same time preventing ion-induced surface erosion. To this end, we develop a rate equation model of IBAD, which embodies continuous deposition of adatoms and creation of vacancies, recombination of vacancies at adatom island edges, as well as recombination of adatoms at vacancy island edges. These rate equations are solved by numerical simulations based on the particle coalescence method. To determine the optimal growth condition, we find the largest mean size of the vacancy islands leading to their survival. We show that at this onset between the rough and smooth layer-by-layer growth regimes there is a simple exponential relation between the largest size of the vacancy islands and the external control parameters of the growth. 相似文献
84.
Thereza Paiva 《Surface science》2007,601(2):419-424
We study height and roughness distributions of films grown with discrete Kardar-Parisi-Zhang (KPZ) models in a small time regime which is expected to parallel the typical experimental conditions. Those distributions are measured with square windows of sizes 8 ? r ? 128 gliding through a much larger surface. Results for models with weak finite-size corrections indicate that the absolute value of the skewness and the value of the kurtosis of height distributions converge to 0.2 ? ∣S∣ ? 0.3 and 0 ? Q ? 0.5, respectively. Despite the low accuracy of these results, they give additional support to a recent claim of KPZ scaling in oligomer films. However, there are significant finite-size effects in the scaled height distributions of models with large local slopes, such as ballistic deposition, which suggests that comparison of height distributions must not be used to rule out KPZ scaling. On the other hand, roughness distributions of the same models show good data collapse, with negligible dependence on time and window size. The estimates of skewness and kurtosis for roughness distributions are 1.7 ? S ? 2 and 3 ? Q ? 7. A stretched exponential tail was found, which seems to be a particular feature of KPZ systems in 2 + 1 dimensions. Moreover, the KPZ roughness distributions cannot be fitted by those of 1/fα noise. This study suggests that the roughness distribution is the best option to test KPZ scaling in the growth regime, and provides quantitative data for future comparison with other models or experiments. 相似文献
85.
A theoretical epitaxial growth model with realistic barriers for surface diffusion is investigated by means of kinetic Monte Carlo simulations to study the growth modes of metastable (3 3 1) nanofacets on Au and Pt(1 1 0) surfaces. The results show that under experimental atomic fluxes, the (3 3 1) nanofacets grow by 2D nucleation at low temperature in the submonolayer regime. A metastable growth phase diagram that can be useful to experimentalists is presented and looks similar to the one found for the stationary growth of the bcc(0 0 1) surface in the kinetic 6-vertex model. 相似文献
86.
The bulk and surface properties of Ag-Au alloys, for the whole range of concentration and as a function of temperature, is studied by means of a simple modeling scheme using the Bozzolo-Ferrante-Smith method for alloys. Evidence for short-range order is found and explained, as well as its relationship with the experimentally observed segregation behavior. 相似文献
87.
The possibilities of graphic STM image simulation of a clean Si(1 1 1) 7 × 7 surface at atomic level are indicated. The presented procedure takes into account various types of deformation on the surface near the Fermi level in order to classify them and explain their origin. It also gives a clear hint to insert relevant physical phenomena in a suggested analysis. This goal is achieved exploiting the results of DAS (dimmer adatom stacing fault) model by means of standard mathematical programmes. A clean Si(1 1 1) 7 × 7 surface is considered as the representative example, but similar evaluation is possible for another non-metal and metal surfaces. 相似文献
88.
This paper presents the experience gained by developers and users with implementation and operation of NorTRACKTM, a real-time computerized product tracking system. A Programmable Logic Controller (PLC) collects and transfers data in real time to NorTRACK’s OracleTM database on a Windows NTTM server network. After extensive development and Beta testing at MDS Nordion’s Canadian Irradiation Centre in Montreal, Canada, NorTRACK was installed in January 1997 with a new irradiation facility in Ethicon Endo-Surgery Inc.’s Albuquerque plant in the United States. NorTRACK communicates with the irradiator control and safety system, the plant's central manufacturing database, an innovative pallet staging and tote loading robot, and an automated dosimetry reading system. This integrated system allows the sterilization facility to monitor the irradiator operation and the flow of many products, through varied processing modes, continuously and reliably. As a result of operating with NorTRACK, both MDS Nordion’s CIC facility and the Endo-Surgery manufacturing site, are beginning to realize unique benefits in their respective operations. MDS Nordion is also initiating several future product enhancements and additional productivity modules. This paper describes the NorTRACK system, the various stages of the development project and Beta tests, and the experience of the users to date in their operations. 相似文献
89.
90.
P.G. Khalatur A.R. Khokhlov S.A. Prokhorova S.S. Sheiko M. Möller P. Reineker D.G. Shirvanyanz N. Starovoitova 《The European physical journal. E, Soft matter》2000,1(1):99-103
Conformational properties of comb-like polymers strongly adsorbed on a flat solid surface were investigated using computer
simulation and scanning force microscopy. The computer simulation showed that the macromolecules with asymmetric distribution
of the side chains relatively to the backbone are effectively in a collapsed state even under conditions of a good solvent.
They formed peculiar helical superstructures which could be observed by scanning force microscopy of cylindrical brushes of
polymethylmethacrylate on mica.
Received 13 September 1999 相似文献