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Sổ tay RFID (P8)
Data Security RFID systems are increasingly being used in high security applications, such as access systems and systems for making payments or issuing tickets. However, the use of RFID systems in these applications necessitates the use of security measures to protect against attempted attacks, in which people try to trick the RFID system in order to gain unauthorised access to buildings or avail themselves of services (tickets) without paying.
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Sổ tay RFID (P9)
Standardisation The development of standards is the responsibility of the technical committee of the ISO. The ISO is the worldwide union of national standardisation institutions, such as DIN (Germany) and ANSI (USA). The description of standards in this chapter merely serves to aid our technical understanding of the RFID applications dealt with in this book and no attempt has been made to describe the standards mentioned in their entirety.
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Sổ tay RFID (P10)
The Architecture of Electronic Data Carriers Before we describe the functionality of the data carriers used in RFID systems we must first differentiate between two fundamental operating principles: there are electronic data carriers based upon integrated circuits (microchips) and data carriers that exploit physical effects for data storage. Both 1-bit transponders and surface wave components belong to the latter category.
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Sổ tay RFID (P11)
Readers Data Flow in an Application A software application that is designed to read data from a contactless data carrier (transponder) or write data to a contactless data carrier, requires a contactless reader as an interface. From the point of view of the application software, access to the data carrier should be as transparent as possible. In other words, the read and write operations should differ as little as possible from the process of accessing comparable data carriers (smart card with contacts, serial EEPROM). ...
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Sổ tay RFID (P12)
Module manufacture In accordance with the normal semiconductor manufacturing procedure, the microchip is produced on a so-called wafer. This is a slice of silicon, which may be 6 inches in diameter, upon which several hundred microchips are produced simultaneously by repeated doping, exposure, etching and washing of the surface. In the next stage of production, the microchips on the wafer are contacted using metal points and then each of the chips is individually tested for functionality.
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Sổ tay RFID (P13)
Example Applications Contactless Smart Cards The first plastic cards appeared in the USA as early as the beginning of the 1950s, when cheap PVC replaced cardboard. In the years that followed, plastic credit cards became widespread. Incidentally, the first credit card was issued by Diners Club in 1950. The rapid development of semiconductor technology made it possible to integrate data memory and protective logic onto a single silicon chip in the 1970s.
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Tán xạ của sóng điện từ P1
TO ELECTROMAGNETIC BY A SINGLE PARTICLE Parameters and Cross Sections Matrix 2 2 6 9 by a Small by a Sphere by an Ellipsoid Particle 9 10 12 14 of Scattering Amplitude and 16 16 18 Waves, and 21 21 22 24 30 Cylinders, Cylinder and Disks Using the Infinite 41 Disk Approximation 46 52 32 32 Length Basic Scattering Amplitudes Amplitude Scattering Scattering Scattering Scattering Dyads Scattering Scattering Rayleigh Rayleigh Rayleigh Rayleigh Scattering 22 . 23 . 24 . 3 . 31 32 . 4 . 41 42 . 43 . 5 6 61 . 62 . 63 . ...
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Tán xạ của sóng điện từ P2
BASIC THEORY OF ELECTROMAGNETIC SCATTERING 1 11 . 12 . . 13 14 . 2 3 4 Dyadic Green’s Function Green’s Functions Plane Wave Represent at ion Cylindrical Waves Spherical Waves Huygens’ Principle and Extinction Sensing and Bistatic Theorem Scattering 54 54 55 57 59 60 66 68 73 73 and Active Remote Coefficients Optical Reciprocity Reciprocity Reciprocal Scattering Symmetry Eulerian T-Matrix T-Matrix Unitarity Theorem
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Tán xạ của sóng điện từ P3
Geophysical media are very often mixtures of different types of particles which can be characterized by many parameters. They can be described by their physical parameters, such as size, concentration or fractional volume, shape, and orientation. They also can be described by the dielectric property which determines the wave
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Tán xạ của sóng điện từ P4
In remote sensing, the model of a layered medium with reflective boundaries for each layer is the simplest model. In this chapter, we will study the scattering and emission by layered media using two different approaches:
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Tán xạ của sóng điện từ P5
In this chapter we study single scattering. We first consider the case of single scattering by a conglomeration of particles. Then we analyze the SAR technique and examine processing algorithms on the basis that the target background response consists of single scattering. We also study active remote sensing of a random medium based on single scattering.
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Tán xạ của sóng điện từ P6
Radiative transfer theory is an important method to treat multiple scattering in medium consisting of random discrete scatteries. Classic books on the subject include Chandrasekhar [1960]; Ishimaru [1978]; Case and Zweifel [1967]. The theory has been extensively applied [Tsang et al., 1977; Tsang et al. 1985; Fung, 1994; Ulaby et al. 1990; Burke et al. 19791.
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Tán xạ của sóng điện từ P7
Iterative Method Iterative Procedure Integral Equation for Scattering Problems Active Remote Sensing of a Half-Space of Spherical Particles Active Remote Sensing of a Layer of Nonspherical Particles 1.4.1 Numerical 1lIustrations with Finite Dielectric Cylinders Second-Order Scattering from Isotropic Point Scatterers Discrete Ordinate-Eigenanalysis Method Radiative Transfer Solution for Laminar Structures Numerical Procedure of Discrete Ordinate Method: Normal Incidence Active Remote Sensing: Oblique Incidence Discrete Ordinate Method for Passive Remote Sensing Passive...
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Tán xạ của sóng điện từ P8
Introduction Statistics Statistics, Characteristic Small Dirichlet Neumann Kirchhoff Dirichlet Neumann References of Random Correlation Functions Method for One-Dimensional for One-Dimensional Surface Surface Rough Function Surface and Spectral Density
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Lịch khai giảng trong các hệ thống thời gian thực P1
Real-Time Applications Real-time applications issues In real-time applications, the timing requirements are the main constraints and their mastering is the predominant factor for assessing the quality of service. Timing constraints span many application areas, such as industrial plant automation, embedded systems, vehicle control, nuclear plant monitoring, scientific experiment guidance, robotics, multimedia audio and video stream conditioning, surgical operation monitoring, and stock exchange orders follow-up....
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Lịch khai giảng trong các hệ thống thời gian thực P2
Scheduling of Independent Tasks This chapter deals with scheduling algorithms for independent tasks. The first part of this chapter describes four basic algorithms: rate monotonic, inverse deadline, earliest deadline first, and least laxity first. These algorithms deal with homogeneous sets of tasks, where tasks are either periodic or aperiodic. However, real-time applications often require both types of tasks. In this context, periodic tasks usually have hard timing constraints and are scheduled with one of the four basic algorithms. ...
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Lịch khai giảng trong các hệ thống thời gian thực P3
Scheduling of Dependent Tasks In the previous chapter, we assumed that tasks were independent, i.e. with no relationships between them. But in many real-time systems, inter-task dependencies are necessary for realizing some control activities. In fact, this inter-task cooperation can be expressed in different ways: some tasks have to respect a processing order, data exchanges between tasks, or use of various resources, usually in exclusive mode.
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Lịch khai giảng trong các hệ thống thời gian thực P4
Scheduling Schemes for Handling Overload 4.1 Scheduling Techniques in Overload Conditions This chapter presents several techniques to solve the problem of scheduling real-time tasks in overload conditions. In such situations, the computation time of the task set exceeds the time available on the processor and then deadlines can be missed. Even when applications and the real-time systems have been properly designed, lateness can occur for different reasons, such as missing a task activation signal due to a fault of a device, or the extension of the computation time of some tasks due to concurrent use of shared resources....
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Lịch khai giảng trong các hệ thống thời gian thực P5
Multiprocessor Scheduling In this chapter, we limit the study to multiprocessor systems with centralized control that are called ‘strongly coupled systems’. The main characteristics of such systems are the existence of a common base of time (for global scheduling of events and tasks) and a common memory (for implementing the vector of communication between tasks). Consequently, one has a global view of the state of the system accessible at every moment.
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Lịch khai giảng trong các hệ thống thời gian thực P6
Joint Scheduling of Tasks and Messages in Distributed Systems This chapter and the next one discuss mechanisms to support real-time communications between remote tasks. This chapter deals with some techniques used in multiple access local area networks and Chapter 7 deals with packet scheduling when the communications are supported by packet-switching networks such as ATM or IPbased networks.
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Lịch khai giảng trong các hệ thống thời gian thực P7
Packet Scheduling in Networks The networks under consideration in this chapter have a point-to-point interconnection structure; they are also called multi-hop networks and they use packet-switching techniques. In this case, guaranteeing time constraints is more complicated than for multiple access LANs, seen in the previous chapter, because we have to consider message delivery time constraints across multiple stages (or hops) in the network. In this type of network, there is only one source node for any network link, so the issue to be addressed is not only that of access to the medium but also that of packet scheduling. ...
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Lịch khai giảng trong các hệ thống thời gian thực P8
Software Environment This chapter presents some software components relevant to real-time applications. The first part of the chapter is concerned with operating systems. Real-time requirements for operating system behaviour forbid the use of standard Unix, although the Posix/Unix interface is very useful for software engineering. Three approaches are presented. In the first one, the real-time executive has been customized to provide a Posix interface. This is illustrated by VxWorks, the executive of the Mars Pathfinder rover, which is the second case study which will be presented in Chapter 9....
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Lịch khai giảng trong các hệ thống thời gian thực P9
Case Studies Real-Time Acquisition and Analysis of Rolling Mill Signals Aluminium rolling mill Manufacturing process of an aluminium reel The P´ chiney Rh´ nalu plant processes aluminium intended for the packaging market. e e The manufacturing process of an aluminium reel is made up of five main stages: 1. The founding eliminates scraps and impurities through heat and chemical processes, and prepares aluminium beds of 4 m × 6 m × 0.6 m weighing 8–10 tons.
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Mạng lưới giao thông và đánh giá hiệu suất P1
Since the seminal study of Leland, Taqqu, Willinger, and Wilson [41], which set the groundwork for considering self-similarity an important notion in the understanding of network traf®c including the modeling and analysis of network performance, an explosion of work has ensued investigating the multifaceted nature of this phenomenon.1 The long-held paradigm in the communication and performance communities has been that voice traf®c and, by extension
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Mạng lưới giao thông và đánh giá hiệu suất P2
THE SCALING PHENOMENA Scaling Issues in Traf®c The presence of scaling behavior in telecommunications traf®c is striking not only in its ubiquity, appearing in almost every kind of packet data, but also in the wide range of scales over which the scaling holds (e.g., see Beran et al. [18], Leland et al. [43], and Willinger et al. [78]). It is rare indeed that a physical phenomenon obeys a consistent law over so
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Mạng lưới giao thông và đánh giá hiệu suất P3
Recently the phenomenon of network traf®c self-similarity has received signi®cant attention in the networking community [10]. Asymptotic self-similarity refers to the condition in which a time series's autocorrelation function declines like a power law, leading to positive correlations among widely separated observations. Thus the fact that network traf®c often shows self-similarity means that it shows noticeable bursts at a wide range of time scalesÐtypically at least four or ®ve orders of magnitude. ...
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Mạng lưới giao thông và đánh giá hiệu suất P4
This chapter gives an overview of some properties of the storage occupancy process in a buffer fed with ``fractional Brownian traf®c,'' a Gaussian self-similar process. This model, called here ``fractional Brownian storage,'' is the logically simplest long-range-dependent (LRD) storage system having strictly self-similar input variation. The impact of the self-similarity parameter H can be very clearly illustrated with this model. Even in this case, all the known explicitly calculable formulas for quantities like the storage occupancy distribution are only limit results, for example, large deviation asymptotics. ...
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Mạng lưới giao thông và đánh giá hiệu suất P5
In this chapter, we evaluate the impact of long-range dependence on a single network element (multiplexer or router) of a data network, this element being modeled as a ¯uid queueing system. Such a system has constant output rate C and is fed by a number N of i.i.d. on=off traf®c sources. The case where the number of sources N is ®xed is treated, for instance, in Boxma and Dumas [4].
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Mạng lưới giao thông và đánh giá hiệu suất P6
Recently, there has been much interest in the behavior of queues with heavy-tailed service time distributions. This interest has been triggered by a large number of traf®c measurements on modern communication network traf®c (e.g., see Willinger et al. [38] for Ethernet LAN traf®c, Paxson and Floyd [30] for WAN traf®c, and Beran et al. [3] for VBR video traf®c; see also various chapters in this volume).
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Mạng lưới giao thông và đánh giá hiệu suất P7
Large teletraf®c data sets exhibiting nonstandard features incompatible with classical assumptions of short-range dependence and exponentially decreasing tails can now be explored, for instance, at the ITA Web site www.acm.org=sigcomm=ITA=. These data sets exhibit the phenomena of heavy-tailed marginal distributions and long-range dependence. Tails can be so heavy that only in®nite variance models are possible (e.g., see Willinger et al. [49]), and sometimes, as in ®le size data, even ®rst moments are in®nite [1]...
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