Error Analysis of the Anti-Causal Realization of Periodic Inverse Systems

A causal realization of an inverse system can be unstable, and an anti-causal realization is used to deal with this problem to provide a numerically stable procedure to realize the inverse system and compute its input signal. In this paper, we consider the anti-causal realization of the inverse of discrete-time linear periodic systems obtained by an outer-inner factorization approach. It presents an analysis and understanding of the inverse system error caused by different parts of the system components. The analysis shows that the inverse system error due to the mismatching of the system initial state in the anti-causal inverse system is inevitable in practical computations.     

On the Realization of Multiphase Oscillators Using?Fractional-Order Allpass Filters

In this paper multiphase oscillators built using fractional-order allpass filters are presented. We examine the theory behind their operation and demonstrate their usefulness in the design of both multiphase and quadrature oscillators. Case design examples are given for various scenarios, while PSPICE and experimental results verify their operation     

New Solutions for Distributed Realization of 8 × 1 MISO channel with QOSTBC

We proposed new solutions for distributed realization of the quasi orthogonal space-time block coding (QOSTBC), which is designed for 8 × 1 multiple input–single output (MISO) system. The first proposed solution assumes that base station and relay stations are equipped with 2 antennas, while for the second solution base station is equipped with 4 antennas and relay stations are with one antenna. In both scenarios mobile unit is equipped with single antenna. The proposed solutions are compared with distributed QOSTBC which is used for 4 × 1 MISO system. The simulation results show BER performances improvements provided with the proposed solutions in comparison with distributed QOSTBC designed for 4 × 1 MISO. It was shown that the first proposed scheme provides lower BER values than the second solution. Also, beside ideal channel estimation, influence of real estimation errors on BER performances is considered.     

On the Relationships between Notions of Simulation-Based Security

Several compositional forms of simulation-based security have been proposed in the literature, including Universal Composability, Black-Box Simulatability, and variants thereof. These relations between a protocol and an ideal functionality are similar enough that they can be ordered from strongest to weakest according to the logical form of their definitions. However, determining whether two relations are in fact identical depends on some subtle features that have not been brought out in previous studies. We identify two main factors: the position of a “master process” in the distributed system and some limitations on transparent message forwarding within computational complexity bounds. Using a general computational framework, called Sequential Probabilistic Process Calculus (SPPC), we clarify the relationships between the simulation-based security conditions. Many of the proofs are carried out based on a small set of equivalence principles involving processes and distributed systems. These equivalences exhibit the essential properties needed to prove relationships between security notions and allow us to carry over our results to those computational models which satisfy these equivalences.     

On the Realization of Current－Mode Continuous－Time Operational Transconductance Capacitance Filter

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On the move with RFID

Scanology is an independent automatic identification specialist providing state of the art barcode and RFID solutions to our European customer base. Our knowledge of the present and what is yet to come allows us to provide honest, practical advice to clients transitioning from barcode to RFID. Scanology designs, builds, installs and services end-to-end sup-     

1.0 THz GaN IMPATT Source: Effect of Parasitic Series Resistance

The degradation of high-frequency characteristics of a 1.0-THz double-drift region (DDR) impact avalanche transit time (IMPATT) diode based on wurtzite gallium nitride (Wz-GaN), due to the influence of parasitic series resistance, has been investigated. A two-dimensional (2-D) large-signal (L-S) simulation method based on a non-sinusoidal voltage excitation (NSVE) model has been used for this purpose. A comprehensive model of series resistance has been developed by considering the influence of skin effect, and the said model has been incorporated in the 2-D L-S simulation for studying the effect of RF power output and DC to RF conversion efficiency of the device. Results indicate 24.2–35.9% reduction in power output and efficiency due to the RF power dissipation in the positive series resistance. However, the device can still deliver 191.7–202.9 mW peak RF power to the load at 1.0 THz with 8.48–6.41% conversion efficiency. GaN IMPATT diodes are capable of generating higher RF power at around 1 THz than conventional diodes, but the effect of parasitic series resistance causes havoc reduction in power output and efficiency. The nature of the parasitic resistance is studied here in the level of device fabrication and optimization, which to our knowledge is not available at present.     

Realization of Tapered Waveguide by Stretching the Rod Waveguide

By stretching the rod waveguide with different velocities in opposite directions, the tapered waveguide can be fabricated. In condition of taking no account of volume expansion caused by heating and under the assumptions of volume conservation,the rod waveguide can be stretched freely in the heated region without being stretched outside of the heated region. A model,which shows the relation of the transition shape and the two factors, that is the ratio of two velocity and the heated region length, is presented for the shape of the taper transition through mathematic deduction. Based on this model, a desired tapered waveguide can be fabricated. The tapered waveguide are widely used for fabricating tapered fiber couplers and sensors. In addition, the conclusion can be used for fabricating fused fiber coupler.     

A Study of the Effects of the Current InternationalSettlement of Internet

1　TheUnbalancedDevelopmentofInternetandtheDigitalDivideAmongCountries　　Withtheadvanceofinformationtechnology ,Internethaspenetratedintovariousaspectsofsocialandeconomiclifedeeplyandimprovedthedevelop mentofproductivityenormously ,which producestheobvioustendencyofeconomicglobalization .In ternetexpeditestheprocessofeconomicglobaliza tion ,throughwhichanycountrywouldbeabletoparticipateintheglobalproductionandrebuildingthetraditionalindustrymoreintensivelyandexten sively.Alotofnewinformati…     

An Analysis of the Blockcipher-Based Hash Functions from PGV

Preneel, Govaerts, and Vandewalle (1993) considered the 64 most basic ways to construct a hash function $H{:\;\:}\{0,1\}^{*}\rightarrow \{0,1\}^{n}Preneel, Govaerts, and Vandewalle (1993) considered the 64 most basic ways to construct a hash function H:   {0,1}^*? {0,1}ⁿH{:\;\:}\{0,1\}^{*}\rightarrow \{0,1\}^{n} from a blockcipher E:   {0,1}ⁿ×{0,1}ⁿ? {0,1}ⁿE{:\;\:}\{0,1\}^{n}\times \{0,1\}^{n}\rightarrow \{0,1\}^{n}. They regarded 12 of these 64 schemes as secure, though no proofs or formal claims were given. Here we provide a proof-based treatment of the PGV schemes. We show that, in the ideal-cipher model, the 12 schemes considered secure by PGV really are secure: we give tight upper and lower bounds on their collision resistance. Furthermore, by stepping outside of the Merkle–Damg?rd approach to analysis, we show that an additional 8 of the PGV schemes are just as collision resistant (up to a constant). Nonetheless, we are able to differentiate among the 20 collision-resistant schemes by considering their preimage resistance: only the 12 initial schemes enjoy optimal preimage resistance. Our work demonstrates that proving ideal-cipher-model bounds is a feasible and useful step for understanding the security of blockcipher-based hash-function constructions.     

On the origin of 1/ƒ noise

A new model describing a mechanism which produces l/? noise in resistors is given. In this model fast surface states produce a time varying component in the conductivity of a resistor which gives rise to the l/? spectral behaviour.     

On the Use of Radiometric Measurements to Estimate Atmospheric Attenuation at 100 and 300 GHz

At frequencies of between 100 GHz and 30 THz, propagation conditions are severely affected by the influence of the composition and phenomena of the troposphere. This paper focuses on the use of radiometric measurements to estimate attenuation at 100 and 300 GHz, considering non-scattering scenarios, in which the main contributions are given by atmospheric gases and non-rainy clouds. These techniques allow the estimation of the absorption loss through the entire atmosphere, without the need for a signal source situated in a satellite or a high altitude aircraft. On the basis of well-accepted absorption models, the results of calculating gaseous, cloud, and total attenuation using 3-year meteorological data from Madrid, Spain, are detailed, as well as estimates of the expected values of the sky brightness temperature as measured by the radiometer. Finally, based on the results obtained, a discussion on the use of radiometric measurements at both frequencies is presented, in connection with an experimental campaign currently under preparation.     

Performance Analysis of a Sectorized Distributed Antenna System with Reduced Co-Channel Interference

1IntroductionThe next generation mobile communication systemissupposedto provide high data rate services such as Inter-net access and multi media applications whichare morelikelyto be affected by Inter-Symbol-Interference(ISI)inwireless multi-path fading …     

Realization of two-dimensional recursive digital filters using the mixed Cauer form†

The application of the mixed cauer continued fraction expansion to synthesis of two-dimensional recursive digital filters is presented. Examples are provided to show how to perform a mixed cauer expansion on two-dimensional transfer functions and eventually obtain canonic digital ladder filter structures. Furthermore, a test for two-dimensional mixed-cauer continued fraction expansion which at the same time determines the expansion coefficients is included.     

On the Electret Effect in Polymer–Ferroelectric Piezoceramic Composites with Various Values of the Electronegativity of the Polymer Matrix and Piezophase Cations

The influence of the electronegativity of phases, which is controlled by composite crystallization under the conditions of the effect of the electric discharge and covalence of piezophase cations, on the formation mechanism of the stable electret effect is determined. The specific features of the formation of the electret effect in composites based on polyolefins (HDPE, PP), fluorine-containing polymers (F42), and ferroelectric piezoelectric ceramics of the family of lead zirconate–titanate (Pb(Zr,Ti)O₃) crystallized under conditions of the effect of electric discharge plasma, are revealed. A physical model of electret composites taking into account the role of homocharges and heterocharges formed in a composite by its dispersion with piezoceramic particles of various structures—rhombohedral, tetragonal, and heterogeneous—is proposed.     

Performance analysis of the IEEE 802.11e wireless networks with TCP ACK prioritization

With the advent of multimedia over wireless local area networks, the IEEE 802.11e standard was proposed to incorporate Quality of Service (QoS). It has been found that the throughput of Transmission Control Protocol (TCP) is less than that of User Datagram Protocol (UDP) in the IEEE 802.11e. This is because the TCP acknowledgment packets are queued up at the access points. In this paper, two types of TCP acknowledgment prioritizing schemes are proposed. The proposed schemes improve the overall throughput of TCP while maintaining the QoS requirements. We also analyze the problem of starvation of lower priority traffic and its effects on the performance of lower priority TCP traffic. The proposed dynamic scheme of TCP acknowledgment prioritization aims at improving the throughput of the lower priority TCP traffic under heavy network load while maintaining the QoS requirements of the higher priority traffic. The schemes have been verified through extensive simulation.     

On the Selection of Random Numbers in the ElGamal Algorithm

Generally speaking, parameter selection in all cryptographic algorithms and protocols is a mixture of art and science and exerts various subtle influences on a system, which is related to application requirements, security policies, the compromise between security and the overheads of computation, storage and communications, the balance between security and availability, and to the efficiency of software /hardware implementation, etc. Usually, simplistic, insecure or impractical textbook crypto…     

On the Selection of Random Numbers in the EIGamal Algorithm

The EIGamal algorithm, which can be used for both signature and encryption, is of importance in public-key cryptosystems. However, there has arisen an issue that different criteria of selecting a random number are used for the same algorithm. In the aspects of the sufficiency, necessity, security and computational overhead of parameter selection, this paper analyzes these criteria in a comparative manner and points out the insecurities in some textbook cryptographic schemes. Meanwhile, in order to enhance security a novel generalization of the EIGamal signature scheme is made by expanding the range of selecting random numbers at an acceptable cost of additional computation, and its feasibility is demonstrated.     

On the Bandwidth of RFT Interconnection Network in the Presence of Faulty Components

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On the Uçar prototype model with incommensurate delays

Differential-difference equations with multiple delays have applications in a variety of applied fields. We propose a prototype delay model introduced by Uçar involving two delays. Sufficient conditions for the stability of the model are given and used to study chaos. It is observed first time in the literature that the Uçar system shows not only two-scroll but also one-scroll chaotic attractors.