Sharif Digital Repository

In Analog to Digital Converters, the sampled values are not necessarily sampled in the desired time. Sampling may occur before or after the desired time because of using non ideal converters; therefore the output signal of converters contains a noise related to this inexact sampling time. In this paper, signal to noise ratio according to practical sampling of continuous signal will be estimated. For this estimation, we have assumed the continuous signal as a band limited, zero-mean real signal which is wide sense stationary (wss). Sampling rate is also considered equal or more than Nyquist sampling rate. It will be concluded that what condition should be applied in order to have any... 

In this paper, the optimal sampling strategies (uniform or nonuniform) and distortion tradeoffs for stationary bandlimited periodic signals are studied. We justify and use both the average and variance of distortion as the performance criteria. To compute the optimal distortion, one needs to find the optimal sampling locations, as well as the optimal pre-sampling filter. A complete characterization of the optimal distortion for the rates lower than half the Landau rate is provided. It is shown that nonuniform sampling outperforms uniform sampling. In addition, this nonuniform sampling is robust with respect to missing samples. Next, for the rates higher than half the Landau rate, we find... 

In the communication problem UR (universal relation), Alice and Bob respectively receive x, y {0,1}^n with the promise that xy. The last player to receive a message must output an index i such that x-iy-i. We prove that the randomized one-way communication complexity of this problem in the public coin model is exactly Θ(min{n,log(1/Δ)log^2(rac n{log(1/Δ)})}) for failure probability Δ. Our lower bound holds even if promised mathop{support}(y)mathop{support}(x). As a corollary, we obtain optimal lower bounds for -p-sampling in strict turnstile streams for 0le p streams for 0 ≤ p © 2017 IEEE  

The first objective of this paper is to derive the total cost for one of the most commonly used continuous sampling plans in industry. The total cost includes the costs of inspection, reworks, and defective items returned by the customers. The continuous sampling plan under study is commonly known as CSP-1 which consists of alternate sequences of 100% inspection and random inspection used in continuous production systems. To achieve this objective, we employ the concepts of the renewal reward processes to obtain the long run average unit cost of the sampling plan. The second and the more important objective of this paper is to derive the minimum cost policy for the above sampling plan. The... 

Partially-observed data collected by sampling methods is often being studied to obtain the characteristics of information diffusion networks. However, these methods usually do not consider the behavior of diffusion process. In this paper, we propose a novel two-step (sampling/estimation) measurement framework by utilizing the diffusion process characteristics. To this end, we propose a link-tracing based sampling design which uses the infection times as local information without any knowledge about the latent structure of diffusion network. To correct the bias of sampled data, we introduce three estimators for different categories, link-based, node-based, and cascade-based. To the best of... 

In this study, operation of the contact Cylindrical Capacitive Sensor (CCS) for the reactance capacitance measurement of the water liquids by using the charge/discharge measurement module is investigated. The effect of geometric factor on the capacitance measurement of different liquid samples is also studied. The measured capacitances for the distilled, mineral, tap and salt water samples are reported by using two contact CCSs with the active length of 16 and 74 mm. The measured capacitances by small contact CCS for the saltwater is 1.76 uF and by big contact CCS is 47.8 uF, which shows a big difference for different probes. In another study, the effects of the liquid conductance on the... 

Progressive image transmission enables the receivers to reconstruct a transmitted image at various bit rates. Most of the works in this field are based on the conventional Shannon-Nyquist sampling theory. In the present work, progressive image transmission is investigated using sparse recovery of random samples. The sparse recovery methods such as Iterative Method with Adaptive Thresholding (IMAT) and Iterative IKMAX Thresholding (IKMAX) are exploited in this framework since they have the ability for successive reconstruction. The simulation results indicate that the proposed method performs well in progressive recovery. The IKMAX has better final reconstruction than IMAT at the cost of... 

While the main assumption of an economic model of a variable sample size and sampling interval (VSSI) X-Bar control chart is normality, some process data may not follow a normal distribution. In this paper, a model for an economic design of the VSSI X-Bar chart under non-normality of the process data is first developed. Then a parameter-tuned genetic algorithm is proposed to solve the model and compare its performances in terms of the expected loss per hour to the ones of a fixed sample size and sampling interval X-Bar control charts that works under the normality assumption. Finally, a numerical example is given to illustrate the applications of the proposed methodology and to perform a... 

While the main assumption of an economic model of a variable sample size and sampling interval (VSSI) X-Bar control chart is normality, some process data may not follow a normal distribution. In this paper, a model for an economic design of the VSSI X-Bar chart under non-normality of the process data is first developed. Then a parameter-tuned genetic algorithm is proposed to solve the model and compare its performances in terms of the expected loss per hour to the ones of a fixed sample size and sampling interval X-Bar control charts that works under the normality assumption. Finally, a numerical example is given to illustrate the applications of the proposed methodology and to perform a... 

One of the proposed methods for recovery of a band-limited signal from its samples, whether uniform or nonuniform, is the so-called Frame Method. In this method the original signal is reconstructed by iterative use of sampling-filtering blocks. Convergence of this method for linear invertible operators has been previously proved. In this paper we show that this method for non-invertible periodic nonuniform samplings as well as non-invertible uniform samples of bandpass (or multi-band) signals will lead to the pseudo-inverse solution. Convergence conditions in case of additive noise will also be discussed. © 2008 Sampling Publishing  

In the experimental verification of Bell's inequalities in real photonic experiments, it is generally believed that the so-called fair sampling assumption (which means that a small fraction of results provide a fair statistical sample) has an unavoidable role. Here, we want to show that the interpretation of these experiments could be feasible, if some different alternative assumptions other than the fair sampling were used. For this purpose, we derive an efficient Bell-type inequality which is a CHSH-type inequality in real experiments. Quantum mechanics violates our proposed inequality, independent of the detection-efficiency problems. © 2005 Taylor & Francis Group Ltd  

In this research, Repetitive Group Sampling (RGS) plans are developed for the Weibull and generalized exponential distributions. To design the proposed plans, the median of a life-time is first used as the quality parameter. Then, a decision-making framework is developed, based on first and second type errors. Next, based on acceptable and limiting quality level criteria, tables are obtained to select the parameters of the proposed decision-making framework. The advantages of the proposed method over single sampling plans are discussed at the end  

Sparse signal processing has found various applications in different research areas where the sparsity of the signal of interest plays a significant role in addressing their ill-posedness. In this invited paper, we give a brief review of a number of such applications in inverse scattering of microwave medical imaging, compressed video sensing, and missing sample recovery based on sparsity. Moreover, some of our recent results on these areas have been reported which confirms the fact that leveraging the sparsity prior of the underlying signal can improve different processing tasks in various problems. © 2016 IEEE  

The main task of a reconnaissance receiver is to acquire wide-band radio signals of the environment and extract their important parameters/information. Direction of arrival (DOA) and carrier frequency are the two most important parameters that a reconnaissance receiver should extract. To extract internal information of the signals such as signal modulation and coded information, complete reception of the signals is necessary. Sub-Nyquist sampling is used in this study for signal conversion from analog to digital with a much reduced sampling rate compared to the carrier frequency and, phase interferometery is used for direction finding. In jointly designing of sub-Nyquist sampling and phase... 

In this paper, the optimal sampling strategies (uniform or nonuniform) and distortion tradeoffs for Gaussian bandlimited periodic signals with additive white Gaussian noise are studied. Our emphasis is on characterizing the optimal sampling locations as well as the optimal pre-sampling filter to minimize the reconstruction distortion. We first show that to achieve the optimal distortion, no pre-sampling filter is necessary for any arbitrary sampling rate. Then, we provide a complete characterization of optimal distortion for low and high sampling rates (with respect to the signal bandwidth). We also provide bounds on the reconstruction distortion for rates in the intermediate region. It is... 

In this paper, the optimal sampling strategies (uniform or nonuniform) and distortion tradeoffs for Gaussian bandlimited periodic signals with additive white Gaussian noise are studied. Our emphasis is on characterizing the optimal sampling locations as well as the optimal presampling filter to minimize the reconstruction distortion. We first show that to achieve the optimal distortion, no presampling filter is necessary for any arbitrary sampling rate. Then, we provide a complete characterization of optimal distortion for low and high sampling rates (with respect to the signal bandwidth). We also provide bounds on the reconstruction distortion for rates in the intermediate region. It is... 

In this paper we present a sampling result about continuous-domain black and white images that form a convex shape. In particular, we will study shapes whose boundaries belong to the zero-level sets (roots) of bivariate polynomials. In [1] it was shown that generalized 2D moments of the image can lead to annihilation equations for the coefficients of the bivariate polynomial that determine the boundary of the shape. More precisely, when the bivariate polynomial is of degree n (which has n(n+3)/2 non-trivial coefficients), the results in [1] indicate that for invertibility of the linear annihilation equations, 2D moments of up to degree 3n-1 (overall equation moments) are required. In this... 

A low voltage current mode sample and hold (S/H) in 0.18μm technology with 1.5v supply voltage is presented. This S/H has 12-bit linearity, i.e., gain and nonlinearity errors of S/H are less than 0.02μA for 100uA input current. Maximum sampling rate for this structure is 100 MHz (using double sampling technique). © 2005 IEEE