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1.
Developments of systems for continuous simulation of streamflow are traced from manual systems in the middle of the 20th century to present day computer-based systems. A profusion of different systems from very simple to very complex are in use. Systems in operational use in UK/Europe, USA, South Africa and Australia are reviewed. There are several different runoff generation processes used in these systems such as saturation overland flow, subsurface stormflow and infiltration excess. These processes demonstrate different approaches to hydrological modelling in different areas. Other differences include the use of processes such as snowmelt and transmission loss that are significant in some areas but not in others. A feature of many modern systems is the use of stochastic rainfall generators that allow for very long streamflow sequences to be generated from which long-term flood statistics can be extracted. Only a few studies have compared continuous simulation with other methods of design flood estimation, and no significant studies have been made comparing different continuous simulation systems. Most of the available systems use recorded streamflow data for calibration and there is little information available for the use of continuous simulation systems on ungauged catchments. 相似文献
2.
In this paper a statistical approach to error location and correction for data stored in secondary memories is developed. The approach is based on the observation that the data records in secondary storage have some inherent redundancy of information. This redundancy cannot precisely be predicted as in the case of typical error correction scheme's artificial redundancy. However, the redundancy can be exploited to provide error correction with some degree of confidence. We use simple and weighted checksum schemes for error detection and present algorithms for single and multiple error correction using statistical error location and correction (SELAC). An implementation of SELAC will be described with an elaborate study of its error-correction capabilities. A conspicuous aspect of SELAC is that it will not cost any processor time and storage overhead until after an error is encountered, unlike the classical schemes using single error correcting-double error detecting (SEC-DED) and double error correcting-triple error detecting (DEC-TED) codes. 相似文献
3.
AbstractThree-dimensional projection installations are particular kinds of augmented spaces in which a digital 3-D model is projected onto a physical three-dimensional object, thereby fusing the digital content and the physical object. Based on interaction design research and media studies, this article contributes to the understanding of the distinctive characteristics of such a new medium, and identifies three strategies for designing 3-D projection installations: establishing space; interplay between the digital and the physical; and transformation of materiality. The principal empirical case, From Fingerplan to Loop City, is a 3-D projection installation presenting the history and future of city planning for the Copenhagen area in Denmark. The installation was presented as part of the 12th Architecture Biennale in Venice in 2010. 相似文献
4.
We propose a new constructive algorithm, called HAPE3 D, which is a heuristic algorithm based on the principle of minimum total potential energy for the 3D irregular packing problem, involving packing a set of irregularly shaped polyhedrons into a box-shaped container with fixed width and length but unconstrained height. The objective is to allocate all the polyhedrons in the container, and thus minimize the waste or maximize profit. HAPE3 D can deal with arbitrarily shaped polyhedrons, which can be rotated around each coordinate axis at different angles. The most outstanding merit is that HAPE3 D does not need to calculate no-fit polyhedron(NFP), which is a huge obstacle for the 3D packing problem. HAPE3 D can also be hybridized with a meta-heuristic algorithm such as simulated annealing. Two groups of computational experiments demonstrate the good performance of HAPE3 D and prove that it can be hybridized quite well with a meta-heuristic algorithm to further improve the packing quality. 相似文献
5.
Many recent advances have been made in data storage and communications media. However, the explosive proliferation of information and the continuous growth of data applications are outgrowing any technological advances in storage devices and communications tools. Data compression offers an attractive approach to alleviate many of the problems associated with data proliferation. In this paper, we present a new double compression scheme for text, program source and documentation files. The first phase of compression is a dictionary-based method that also uses run-length encoding. The second phase of compression is based on utilizing the distributional and correlational properties of the output of the first phase. The technique achieves high degrees of compression and is further enhanced by the hardware assistance that VLSI technology will eventually offer to the realization of data compression techniques. 相似文献
6.
This paper deals with the H∞ filter design problem for a class of discrete-time Lipschitz nonlinear singular systems. The approach is based on the parameterisation of the obtained algebraic constraints from the estimation errors. Sufficient conditions for the existence of the filters which guarantee stability and the worst case filter error energy over all bounded energy disturbances is minimised are given. The method also unifies the design for the full-order, reduced-order, minimal-order filters for discrete- time systems. The presented results are less conservative than those existing in the literature, this is due to the introduction of new slack variables. Application to systems with unknown input is presented via a numerical example. 相似文献
7.
Quantum dot Cellular Automata (QCA) is an emerging nanotechnology, potentially suitable to replace the popular technologies like Complementary Metal Oxide Semiconductor (CMOS) technology. The evolution of QCA has become prominent due to high operating frequency, nanoscale device and zero current low power nanotechnology. However, the Area-Delay-Energy aware QCA logic circuit design remains a prime concern in this post CMOS technology. In this work the primary attention is given to build efficient QCA circuits. The motivation of this work is to propose Efficient VLSI design in terms of Area, Delay, Power and PDP (Power delay product). Different methodologies are reported to design a combinational and sequential circuit in QCA technology. An extensive focus is given in designing of 3 different QCA based Area-Delay-Energy aware SRAM memory cells, parallel read/write M × N SRAM memory array and peripherals like decoder and multiplexer. Since appropriate signal distribution network (SDN) is an essential aspect to deign QCA circuit, it has also been reported a delay aware signal distribution methodology applicable for any type of QCA logic circuit design. The significant results of this research finding are expressed in terms of Area-Delay-Energy dissipation tradeoff. When compared with respective to the state of art, the performance metric of proposed QCA based memory cells are excelled, on an average 40% reduction in area, 33% and 22% drop in delay and energy dissipation respectively are achieved for proposed three different memory cell design. 相似文献
9.
Electronic Markets - The development of business models that boost fundamental changes in behavior to act more economically, ecologically, and socially is a challenging task because the... 相似文献
10.
The context of mobility raises many issues for geospatial applications providing location-based services. Mobile device limitations,
such as small user interface footprint and pen input whilst in motion, result in information overload on such devices and
interfaces which are difficult to navigate and interact with. This has become a major issue as mobile GIS applications are
now being used by a wide group of users, including novice users such as tourists, for whom it is essential to provide easy-to-use
applications. Despite this, comparatively little research has been conducted to address the mobility problem. We are particularly
concerned with the limited interaction techniques available to users of mobile GIS which play a primary role in contributing
to the complexity of using such an application whilst mobile. As such, our research focuses on multimodal interfaces as a
means to present users with a wider choice of modalities for interacting with mobile GIS applications. Multimodal interaction
is particularly advantageous in a mobile context, enabling users of location-based applications to choose the mode of input
that best suits their current task and location. The focus of this article concerns a comprehensive user study which demonstrates
the benefits of multimodal interfaces for mobile geospatial applications. 相似文献
11.
Since its introduction in the 1990s the internet has proliferated in the life of human kind in many numbers of ways. The two by-products of the internet are intelligent agents and intrusions which are far away from each other in the intention of their creation while similar in their characteristics. With automated code roaming the network intruding the users on one side as worms, viruses, and Trojans and autonomous agents tending to help the users on the other side, the internet has given great research challenges to the computer scientists. The greatest challenge of the internet is intrusion, which has increased and never decreased. There are various security systems for the internet. As the Human Immune System protects human body from external attacks, these security systems tend to protect the internet from intruders. Thus the internet security systems are comparable with human immune systems in which autonomous cells move throughout the body to protect it while learning to tackle new threats and keeping them in their memory for the future. These properties are comparable with that of autonomous agents in the internet. Thus intelligent agent technology combined with ideas from human immune system is a great area of research which is still in its developing phase. In this paper, state of the art of security systems which use both these technologies of intelligent agents and artificial immune system i.e., Agent Based Artificial Immune System (ABAIS) for security are reviewed, paying special attention to features of human immune system used in the system, the role of the agents in the ABAIS and the security mechanisms provided against intrusions. 相似文献
12.
In this paper, the issue of H∞ iterative learning controller design is considered for a class of discrete-time systems with data dropouts. With the super-vector formulation of iterative learning control (ILC), such a system can be formulated as a linear discrete-time stochastic system in the iteration domain, and then a sufficient condition guaranteeing both stability of the ILC process and the desired H∞ performance in the iteration domain is presented. The condition can be derived in terms of linear matrix inequalities that can be solved by using existing numerical techniques. A numerical simulation example is also included to validate the theoretical results. 相似文献
13.
Crawler-type vehicles have a considerable importance for rescue operations and tasks performed on disaster-stricken areas. A great deal of research has already been performed on tracked vehicles. However, due to the variety of scenerios in which robots are employed, it is important to design vehicles with high terrain adaptability and that are capable to fulfill different tasks. After an overview of the merits of crawler-type vehicles, the important features of tracked vehicles are introduced and explained. The concept and the mechanical design of a new crawler-type vehicle for rescue operations, named Helios VII, are presented. It consists of two crawlers independently actuated and it is equipped with a manipulator. The novel gripper utilized as an end-effector for the arm is also introduced and tested. Basic experiments on the first assembled prototype are performed to verify the motion capabilities of the vehicle. 相似文献
14.
A novel decentralised indirect adaptive output feedback fuzzy controller with a compensation controller and an H ∞ tracking controller is presented for a class of uncertain large-scale nonlinear systems in this article. The compensator adaptively compensates for interconnections between subsystems as well as mismatched errors, while the H ∞ controller suppresses the effect of external disturbances. Based upon the combination of fuzzy inference systems, a state observer, H ∞ tracking technique and the strictly positive real condition, the proposed overall observer-based decentralised algorithm guarantees not only asymptotical tracking of reference trajectories but also an arbitrary small attenuation level of the unmodelled error dynamics including the disturbances on the tracking control. Simulation results substantiate the effectiveness of the proposed scheme. 相似文献
15.
Reservoir rocks, regardless of what kind (oil-, gas- or water-bearing), are classified by their specific properties. Most rock properties, such as storage, permeability, electric conductivity, heat capacity and so on are determined by laboratory experiments and field tests under different external conditions. Besides temperature, pressure and chemical reactions, also the geometry of the pore space as well as porosity control the specific behaviour of a rock. In most experiments, heterogeneous deformation of the pore space, changes in porosity and inner surface or closing of micro-cracks or pore-throats, cannot be observed directly. To study the dynamic processes behind these changes, we developed the sedimentary tool “Settle3D”. With this software it is possible to generate different clastic rocks in a discrete way, which means that each grain inside this rock can be handled separately. The resulting porous medium can be directly used as import structure for different mechanical, hydraulic and thermal simulations. So the structural information of rocks can be linked to the petrophysical behaviour of porous media. To address these questions, we will present the development as well as the possibilities of “Settle3D”. These include the generation of various 3D grainpacks, handling of input parameters (such as grain size distribution of different materials), sedimentary processes via direct collision procedures and an analysis of the final pore space geometry. 相似文献
16.
Adaptability is emerging as an important attribute or nonfunctional requirement (NFR) for embedded systems. Intuitively, adaptability is the ability of a software system to accommodate changes in its environment. However, in order for the embedded system to be adaptable its architecture, the first step in the development, should itself be adaptable. It will be helpful if the generation of this architecture could be automated. In this paper, we describe a tool called the Software Architecture Adaptability Assistant (SA 3) that helps generate adaptable architectures. SA 3 uses the properties of the NFR Framework, in particular its knowledge base properties, to create a catalog of various constituents of architecture such as components and connections, and then searches the catalog to find adaptable constituents for the architecture. In this paper, we describe the theory behind SA 3 and then describe the tool itself. We then demonstrate the architecture generation capability of the tool for embedded systems. We also discuss why these architectures are adaptable as well as point out directions for further improvement. 相似文献
17.
Stochastic oil spill models have traditionally focussed on the production of statistics for oil on the sea surface and along shorelines. Environmental risk analyses of potential spills therefore have tended to neglect potential risks to organisms in the water column. StatMap fills this void, supplying in addition statistics on the spatial distribution of hydrocarbon concentrations in the water column. This paper describes the model concepts and provides examples of model input and output. 相似文献
18.
In this paper, we prove the uniform-in- regularity for 3D time-dependent Ginzburg–Landau model in superconductivity in the case of Coulomb gauge. Here is the normal conductivity of the superconducting material. 相似文献
19.
Virtual Reality - Virtual reality (VR) controllers are widely used for 3D virtual object selection and manipulation in immersive virtual worlds, while touchscreen-based devices like smartphones or... 相似文献
20.
This paper proposes a systematic methodology to obtain a closed-form formulation for dynamics analysis of a new design of a fully spherical robot that is called a 3(RSS)-S parallel manipulator with real co-axial actuated shafts. The proposed robot can completely rotate about a vertical axis and can be used in celestial orientation and rehabilitation applications. After describing the robot and its inverse position, velocity and acceleration analysis is performed. Next, based on Kane’s method, a methodology for deriving the dynamical equations of motion is developed. The elaborated approach shows that the inverse dynamics of the manipulator can be reduced to solving a system of three linear equations in three unknowns. Finally, a computational algorithm to solve the inverse dynamics of the manipulator is advised and several trajectories of the moving platform are simulated. 相似文献
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