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1.
Synthesis of Brain-State-in-a-Box (BSB) based associative memories   总被引:2,自引:0,他引:2  
Presents a novel synthesis procedure to realize an associative memory using the Generalized-Brain-State-in-a-Box (GBSB) neural model. The implementation yields an interconnection structure that guarantees that the desired memory patterns are stored as asymptotically stable equilibrium points and that possesses very few spurious states. Furthermore, the interconnection structure is in general non-symmetric. Simulation examples are given to illustrate the effectiveness of the proposed synthesis method. The results obtained for the GBSB model are successfully applied to other neural network models.  相似文献
2.
An approach to cyclic protocol validation   总被引:1,自引:0,他引:1  
In this paper, the notion of fair reachability is generalized to cyclic protocols with more than two processes, where all the processes in a protocol are connected via a unidirectional ring and each process might contain internal transitions and can be non-deterministic. We identify ‘indefiniteness’ as a new type of logical error due to reachable internal transition cycles. By properly incorporating internal transitions into the formulation, we show that, with a few modifications, all the previous results established for cyclic protocols without non-deterministic and internal transitions still hold in the augmented model. Furthermore, by combining fair progress and maximal progress during state exploration, we prove that the following three problems are all decidable for Q, the class of cyclic protocols with finite fair reachable state spaces: (1) global state reachability; (2) abstract state reachability; and (3) execution cycle reachability. In the course of the investigation, we also show that detection of k-indefiniteness and k-livelock are decidable for Q.  相似文献
3.
This paper considers the robust control of a finite-dimensional linear time-invariant (FDLTI) continuous-time plant by a static generalized sampled-data hold function (GSHF) controller. It is shown that it is possible to design a static GSHF controller to provide a gain margin as large as desired, and a phase margin of up to 90°. The design is straight-forward, and we illustrate it with an example.  相似文献
4.
Impacts of global climate change are expected to result in greater variation in the seasonality of snowpack, lake ice, and vegetation dynamics in southwest Alaska. All have wide-reaching physical and biological ecosystem effects in the region. We used Moderate Resolution Imaging Spectroradiometer (MODIS) calibrated radiance, snow cover extent, and vegetation index products for interpreting interannual variation in the duration and extent of snowpack, lake ice, and vegetation dynamics for southwest Alaska. The approach integrates multiple seasonal metrics across large ecological regions.Throughout the observation period (2001-2007), snow cover duration was stable within ecoregions, with variable start and end dates. The start of the lake ice season lagged the snow season by 2 to 3 months. Within a given lake, freeze-up dates varied in timing and duration, while break-up dates were more consistent. Vegetation phenology varied less than snow and ice metrics, with start-of-season dates comparatively consistent across years. The start of growing season and snow melt were related to one another as they are both temperature dependent. Higher than average temperatures during the El Niño winter of 2002-2003 were expressed in anomalous ice and snow season patterns. We are developing a consistent, MODIS-based dataset that will be used to monitor temporal trends of each of these seasonal metrics and to map areas of change for the study area.  相似文献
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6.
The introduction of a computer, whether it is an integral part of a larger system or not, brings with it many security problems that must be addressed. Frequently the new security needs are the results of the loss of old security measures, such as separation of duties or access control to documents, destroyed by the introduction of new equipment. Also, one must now protect the equipment from theft, environment hazards, and both careless and malicious acts of individuals.

In “the good old days” (read ten to twenty years ago), computer security was a relatively simple matter, even in a manufacturing environmental. The reason for the apparent simplicity was that the use and impact of computgers was limited. Employees learning how to use a computer could be told “Go ahead. There is nothing you can do that will really hurt anything,” with a fair chance of having been told the trut. Computers were used primarily in business (office) applications with a frew “island” out in the shop. Now, all that has changed. In generally, as computers have gotten closer to the user, security has become more of a problem. In early installations, security has a secure room. Later, users and programmrs submitted their program through a window, then went back later to pick up their results through the same window. Now, access may be from a great distance.

In the new computer integrated environment, whether in office automation or in Computer Integrated Manufacturing (CIM), the impact of bad input into a computer or the deliberate or inadvertent alteration of awhat is already in the computer can have disastrous consquences throughout the business. The acronyms crucial to the automation of the manufacturing and engineering functions (e.g., MRP, CAD, CAM, CAE, DFA, FMS, AS/RS, AGV, CIM, et al) all depends heavily upon file data interdependenc and integrity (which, in turn, depents on file security). Yet, in general, the topics of security, training in security, and the need for security tend to get short shift in industry. We belive that a formal, intense, and continuous information and training program, starting with those officers at the top of the corporation, is needed for a heavily automated company to stand the best chance of having a system that is not violated.  相似文献

7.
This paper presents the development of a straightforward displacement type rectangular finite element for bending of a flat plate with the inclusion of transverse (or lateral) shear effects. The element has 21 degrees of freedom consisting of nine for the lateral displacement of the midplane and 12 for rotations of the normal to the undeformed midplane of the plate (six each for rotations about the x and y axes). The latter are taken as independent of the slopes of the deformed midplane in order to include deformation due to transverse shear. The element is fully conforming and may be orthotropic. At interelement boundaries, the element matches adjacent elements both with respect to lateral displacement of the midplane and the rotations of the normal. Numerical computations for a number of examples are presented. The results show the element to be more flexible than most other finite element models and agree closely with those from a numerical solution of the three dimensional elasticity equations. The results also converge to those from thin plate theory when the thickness to length ratio becomes small or when the transverse shear moduli are artificially increased.  相似文献
8.
In adaptive control the goal is to design a controller to control an uncertain system whose parameters may be changing with time. Typically the controller consists of an identifier (or tuner) which is used to adjust the parameters of a linear time-invariant (LTI) compensator, and under suitable assumptions on the plant model uncertainty it is proven that good asymptotic behaviour is achieved, such as model matching (for minimum phase systems) or stability. However, a typical adaptive controller does not track time-varying parameters very well, and it is often highly nonlinear, which can result in undesirable behaviour, such as large transients or a large control signal. Furthermore, most adaptive controllers provide only asymptotic tracking, with no ability to design for a pre-specified settling time.Here we propose an alternative approach, which yields a linear periodic controller. Rather than estimating the plant or compensator parameters, instead we estimate what the control signal would be if the plant parameters were known. In this paper we argue the utility of this approach and then examine the first order case in detail, including a simulation. We also explore the benefits and limitations of the approach.  相似文献
9.
An l1-optimal linear time-invariant (LTI) compensator may have an order significantly higher than that of the plant. In the state feedback case, there has been recent work exploring the use of nonlinear static feedback controllers which provide near optimal performance. In the case of D12 square and invertible, we show that it is enough to have the nonlinearity on a particular substate, which can be used to significantly simplify the design problem.  相似文献
10.
An l1-optimal linear time-invariant (LTI) compensator may have an order significantly higher than that of the plant, even when the state is measurable. Recently there has been work exploring the use of nonlinear static feedback controllers which provide near optimal performance. Here we consider a class of nonlinear state feedback controllers and derive superposition-like bounds on both the plant state and the controlled output in the event that the plant initial condition, the disturbance, and the noise are all non-zero.  相似文献
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