Performance Analysis Of Detection Research Articles

Adjacent-block based statistical detection method for self-embedding watermarking techniques

This paper proposes an adjacent-block based statistical detection method for self-embedding watermarking techniques to accurately identify the tampered blocks, and gives an analytical analysis of the tamper detection performance. In the proposed statistical detection method, we take all adjacent blocks of the test block and its mapping block into account and then utilize a statistic-based rule to verify the validity of image blocks. Analytical analysis and experimental results demonstrate that the proposed statistical detection method can identify the tampered blocks with a probability more than 98% even the tampered area is up to 70% of the host image. In addition, the proposed method outperforms conventional self-embedding fragile watermarking algorithms in tamper detection under collage attack and content-tampering attack.

On the Performance Analysis for Fault Detection in Networked Control Systems

This note addresses the study of observer based fault detection problems in networked control systems with stochastically varying transmission delays caused from the communication network. The process and measurement noises are also assumed. The false alarm rate is difficult to obtain it using classical standard robust control methods. For this purpose, the probabilistic robustness theory will be applied. An illustrating example verified on a simulation platform is given.

Active RFID System With Spread-Spectrum Transmission

In this paper, we propose a new direct-sequence code division multiple access (DS-CDMA)-based transmission scheme for active, transmitter-only radio frequency identification (RFID) tags. We present the architecture of the system, as well as the mathematical analysis of detection performance and system capacity. Because of the good multiple-access properties of DS-CDMA transmission, the proposed system outperforms the classical ALOHA-based RFID system with transmitter-only tags. The obtained analytical results have been verified via computer simulations. Some implementation issues have also been discussed.

Non-asymptotic performance analysis of single-cycle detectors

In this paper, a new formulation of the probabilities of detection and false alarm for a class of cyclic-feature detectors known as single-cycle detectors is derived for additive white Gaussian noise channels. As opposed to previously published papers, the formulation derived here is non-asymptotic, being valid for any signal-to-noise ratio value. Additionally, the proposed formulation is general, allowing for the analysis of the singlecycle detection performance for any modulation scheme and any cycle frequency.

Digitized neutron imaging with high spatial resolution at a low power research reactor: I. Analysis of detector performance

Imaging techniques provide an indispensable tool for investigation of materials. Neutrons, due to their specific properties, offer a unique probe for many aspects of condensed matter. Neutron imaging techniques present a challenging experimental task, especially at a low power research reactor. The Atomic Institute with a 250 kW TRIGA MARK II reactor looks back at a long tradition in neutron imaging. Here we report on the advantages gained in a recent upgrade of the imaging instrument including the acquisition of a thin-plate scintillation detector, a single counting micro-channel plate detector, and an imaging plate detector in combination with a high resolution scanner. We analyze the strengths and limitations of each detector in the field of neutron radiography and tomography, and demonstrate that high resolution digitized imaging down to the 50 μm scale can be accomplished with weak beam intensities of 1.3×10 5 n/cm 2 s, if appropriate measures are taken for the inevitable extension of measurement times. In a separate paper we will present some promising first results from the fields of engineering and geology.

Performance analysis of space-time MMSE multiuser detection for coded DS-CDMA systems in multipath fading channels

This paper investigates the use of convolutional coding in space-time minimum mean-square-error (MMSE) multiuser-based receivers over asynchronous multipath Rayleigh fading channels. We focus on the performance gain attained through error control coding when used with binary-phase-shift-keyed modulation (BPSK) and multiuser access based on direct sequence-code-division multiple access (DS-CDMA). In our analysis, we derive an approximation for the uncoded probability of bit-error in multipath fading channels. This bit-error rate (BER) approximation is shown to be very accurate when compared to the exact performance. For a convolutionally coded system, we obtain a closed form expression for the bit-error rate upper bound. This error bound is noted to be tight as the number of quantization levels increased beyond eight. Using our theoretical results, we obtain an estimate for the achieved user-capacity that accrues due to error control coding. It is found that using convolutional coding with 3-bit soft-decision decoding, a user-capacity gain as much as 300% can easily be achieved when complete fading state information plus ideal channel interleaving are assumed.

Thermal physics of transition edge sensor arrays

Thermal transport in transition edge sensor (TES)-based microcalorimeter arrays is reviewed. The fundamentals of thermal conductance in Si 3N 4 membranes are discussed and the magnitude of the electron–phonon coupling and Kapitza coupling in practical devices is summarized. Next, the thermal transport in high-stopping power and low-heat capacity absorbers, required for arrays of TES microcalorimeters, is discussed in combination with a performance analysis of detectors with mushroom-absorbers. Finally, the phenomenology of unexplained excess noise, observed in both Mo- and Ti-based TESs, is briefly summarized and related with the coupling of the TES to the heat bath.

Performance analysis of ML-CFAR detection for partially correlated chi-square targets in Rayleigh correlated clutter and multiple-target situations

The problem of adaptive constant false alarm rate detection of a pulse-to-pulse partially correlated target with 2K degrees of freedom in pulse-to-pulse partially Rayleigh correlated clutter and multiple-target situations is addressed. Both the target and the clutter covariance matrices are assumed to be known and are modelled as first-order Markov Gaussian processes. An exact expression for the probability of false alarm (Pfa) for the mean level detector is derived. It is shown that it depends on the degree of pulse-to-pulse correlation of the clutter samples. The probability of detection (Pd) is shown to be sensitive to the degree of correlation of the target returns and the degree of correlation of the clutter returns as well. Swerling's well-known cases I, II, III and IV are handled as extreme limits of the proposed model.

CAD performance analysis for pulmonary nodule detection on thin-slice MDCT scans

Early detection of lung nodules is an important clinical indication for obtaining routine CT studies of the thorax. To date, research has mainly focused on the sensitivity of CAD compared with expert chest radiologists using data obtained from single or multi-detector CT scanners. But, beside sensitivity and specificity it is also import to know how well the CAD system does perform on datasets from different sites with different slice thicknesses and differences in the dosage. The present study focuses on the generalization ability of a prototype CAD system that is not yet commercially available. It describes the architecture of a recent CAD system and assesses the performance on a heterogeneous dataset collected from multiple geographically diverse sites.

Modeling and Performance Analysis of Dynamic Random Early Detection (DRED) Gateway for Congestion Avoidance

An international association advancing the multidisciplinary study of informing systems. Founded in 1998, the Informing Science Institute (ISI) is a global community of academics shaping the future of informing science.

Performance Analysis of Multiple-Symbol Differential Detection for OFDM over Both Time- and Frequency-Selective Rayleigh Fading Channels

The performance of orthogonal frequency-division multiplexing (OFDM) system with multiple-symbol differential detection (MSDD) is analyzed over both time- and frequency-selective Rayleigh fading channels. The optimal decision metrics of time-domain MSDD (TD-MSDD) and frequency-domain MSDD (FD-MSDD) are derived by calculating the exact covariance matrix under the assumption that the guard time is longer than the delay spread, thus causing no effective intersymbol interference (ISI). Since the complexity of calculating the exact covariance matrix turns out to be substantial for FD-MSDD, we also develop a sub-optimal metric based on the simplified covariance matrix. The comparative analysis between TD-MSDD and FD-MSDD suggests that the most significant improvement is achieved by the FD-MSDD with the optimal metric and a large symbol observation interval, since the time selectiveness of the channel has a dominant effect on the bit error rate of the OFDM system.

Fault Detection Behavior and Performance Analysis of Principal Component Analysis Based Process Monitoring Methods

Principal component analysis (PCA) is an effective approach to process monitoring, and substantial works in this field have been reported. However, the fault detection behavior and performance of PCA are still equivocal and frequently lead to incorrect understanding of the detection results. This issue is addressed in this paper from two directions simultaneously. First, the expectation formulas of T 2 and squared prediction error statistics are presented and their relations to the statistical parameters of process data are discussed. Based on these relationships, the process disturbances and faults can be differentiated, which makes further fault diagnosis more reliable. Second, detectability conditions of different faults both in the principal subspace and in residual subspace are given. A new conception of critical fault magnitude was introduced to provide a definite description about the fault detection performance of PCA. The acquired results were illustrated and verified by monitoring a simulated double-effective evaporator process.

Performance analysis of maximum likelihood detection in a MIMO antenna system

We provide an analysis of the performance of maximum likelihood detection (MLD) over flat fading channels in a wireless multiple input-multiple output (MIMO) antenna system. A tight union bound with an asymptotic form on the probability of symbol error rate (SER) for MIMO MLD systems with two-dimensional signal constellations (such as QAM and PSK) is introduced. Using this analytic bound, the performance of the MIMO antenna system is demonstrated quantitatively with respect to channel estimation, constellation size, and antenna configuration.

New methods of radar performances analysis

Original methods for radar detection performance analysis are derived for a fluctuating or non-fluctuating target embedded in additive and a priori unknown noise. This kind of noise can be, for example, the sea or ground clutter encountered in surface-based radar for the detection of low grazing angle targets and/or in high-resolution radar. In these cases, the spiky clutter tends to have a statistic which strongly differs from the Gaussian assumption. Therefore, the detection theory is no longer appropriate since the nature of statistics has to be known. The new methods proposed here are based on the parametric modelling of the moment generating function of the noise envelope by Padé approximation, and lead to a powerful estimation of its probability density function. They allow to evaluate the radar detection performances of targets embedded in arbitrary noise without knowledge of the closed form of its statistic and in the same way to take into account any possible fluctuation of the target. These methods have been tested successfully on synthetic signals and used on experimental signals such as ground clutter.

Communication Theory: Letter: Multiuser Detection Analysis in DS-CDMA Channel with Nakagami Fading

In this paper the multiuser detection performance analysis- in synchronous direct sequence code division multiple access (DS-CDMA) system using decorrelating and decision feedback (DFB) receivers, including single path Nakagami fading channel is presented. The lower bounds of the receivers bit error probability (BER) are derived, and the comparison of these receivers' performances to the conventional CDMA receiver is made. The analytical and numerical results show that the DFB receiver performs better in the presence of the high Nakagami fading channels.

Códigos Unipolares para Aplicações em CDMA Óptico

Several code-division multiple access schemes have been proposed for photonic systems. Specifically, for such applications using the non-coherent optical fields superposition principle, most works are focused on the construction of specific codes and its error performance analysis, due the action of the channel noise and/or interference. In opposition, this paper establishes first a theoretical basis on the performance analysis of the unipolar signal detection under additive and strictly positive interference, taking in account either podal or orthogonal signaling. Furthermore, the performance of unipolar CDMA systems is investigated under the perspective of standard detection, or hard limiting techniques. Finally, a new class of time-hopping codes is proposed, which allows large sequence diversity. It has potential to achieve better error performance, when compared to the codes investigated earlier.

DCT-domain watermarking techniques for still images: detector performance analysis and a new structure

In this paper, a spread-spectrum-like discrete cosine transform (DCT) domain watermarking technique for copyright protection of still digital images is analyzed. The DCT is applied in blocks of 8x8 pixels, as in the JPEG algorithm. The watermark can encode information to track illegal misuses. For flexibility purposes, the original image is not necessary during the ownership verification process, so it must be modeled by noise. Two tests are involved in the ownership verification stage: watermark decoding, in which the message carried by the watermark is extracted, and watermark detection, which decides whether a given image contains a watermark generated with a certain key. We apply generalized Gaussian distributions to statistically model the DCT coefficients of the original image and show how the resulting detector structures lead to considerable improvements in performance with respect to the correlation receiver, which has been widely considered in the literature and makes use of the Gaussian noise assumption. As a result of our work, analytical expressions for performance measures, such as the probability of errors in watermark decoding and the probabilities of false alarms and of detection in watermark detection, are derived and contrasted with experimental results.

Performance analysis of direct detection spectrally sliced receivers using Fabry-Perot filters

The use of a spectrally sliced (SS) broad-band source provides a cost effective alternative to laser diode sources for wavelength-division multiplexing (WDM). In this paper the performance of direct detection p-i-n diode intensity modulated SS systems is analyzed using the saddlepoint approximation. Using this approach, based on moment generating functions, the effects of pulse distortion, intersymbol interference (ISI) and nonideal modulator extinction ratios have been included in the analysis of SS systems for the first time. The presence of ISI error floors as the product of optical bandwidth and bit time decreases is demonstrated using a model that agrees with previous work in the case of low bit rate, widely spaced channels. In addition, comparisons with recent experimental results from the literature are made with good agreement. Subsequently, the use of an integrate and dump filter where the integration time starts after the beginning of a bit is investigated and shown to produce significant enhancements to bit-error rate performance. Furthermore, it is shown that a modulator extinction ratio of 20 dB will suffice for 10/sup -9/ bit-error rate (BER) in most cases, with 30 dB offering a performance close to that possible with an ideal modulator. Finally, the likely system power for an SS system is presented.

A parallel code acquisition technique for M-ary orthogonal signals in a cellular CDMA system

Addressed in this paper is a parallel code acquisition technique for M-ary orthogonal signals in a cellular code division multiple access (CDMA) system where pilot signal or preamble is not available for code acquisition. The proposed code acquisition system consists of parallel M-ary orthogonal demodulators each having M correlators. The system also employs two operating modes, i.e., search and verification modes with the decision variables formulated with successive maximums of M correlator outputs. The mean acquisition time is first derived for a multiple H/sub 1/ cell case and then the probabilities of detection, miss, and false alarm are obtained for frequency-selective Rayleigh fading environments. Also provided is a computationally efficient solution for detection performance analysis by using quantized decision variables. The performance of the proposed code acquisition technique is numerically evaluated when it is applied to the initial acquisition of the mobile station requesting hand over.

Simulative performance analysis of gossip failure detection for scalable distributed systems

Three protocols for gossip-based failure detection services in large-scale heterogeneous clusters are analyzed and compared. The basic gossip protocol provides a means by which failures can be detected in large distributed systems in an asynchronous manner without the limits associated with reliable multicasting for group communications. The hierarchical protocol leverages the underlying network topology to achieve faster failure detection. In addition to studying the effectiveness and efficiency of these two agreement protocols, we propose a third protocol that extends the hierarchical approach by piggybacking gossip information on application-generated messages. The protocols are simulated and evaluated with a fault-injection model for scalable distributed systems comprised of clusters of workstations connected by high-performance networks, such as the CPlant system at Sandia National Laboratories. The model supports permanent and transient node and link failures, with rates specified at simulation time, for processors functioning in a fail-silent fashion. Through high-fidelity, CAD-based modeling and simulation, we demonstrate the strengths and weaknesses of each approach in terms of agreement time, number of gossips, and overall scalability.