Sharif Digital Repository

This study provides a stochastic dynamic programming model with a Markov chain that explicitly focuses on the customer as well as a new model for valuing the customers in the banking industry. The proposed framework calculates individual customer’s lifetime value dynamically. The study follows a stochastic dynamic programming model that is based on the Markov chain. The deduced findings are illustrated with supplementary context from an outstanding case study. The findings underline the importance of the stochastic model for calculating customer lifetime value based on customer behavior. The presented framework provides a beneficial way for future research and valuable insight for allocating... 

MOEMS (Micro-Opto-Electro-Mechanical System) are MEMS in which the optical part plays a dominant role. The use of MOEMS as scanners and projectors has been studied lately. For high speed scanning applications, electrostatic comb drive actuation has several advantages. In this paper, we demonstrate the application of sliding mode control scheme for amplitude control of comb-actuated resonant microscanners. This method that leads to a simple and practical control function is simply extendable for microscanners with other type of actuation and even for any kind of oscillators that need amplitude control. The functionality and performance of the presented scheme is verified using numerical  

With advances in technology, Multiple-Input Multiple-Output (MIMO) radars have attracted a lot of attention in different modern military and civilian applications. As there are multiple receivers in a MIMO radar system, the cost can significantly be reduced if we can reduce the sampling rate and send fewer samples to the common processing center. Sometimes, the problem is not even the cost. It is the technology issues of high sampling rates such as the necessity of high-rate Analog-to-Digital (A/D) converters. The reduction in sampling rate can be achieved using Compressive Sensing (CS) or, in a much simpler form, Random Sampling (RS). In CS, we take a number of linear combinations of sparse... 

With advances in technology, Multiple-Input Multiple-Output (MIMO) radars have attracted a lot of attention in different modern military and civilian applications. As there are multiple receivers in a MIMO radar system, the cost can significantly be reduced if we can reduce the sampling rate and send fewer samples to the common processing center. Sometimes, the problem is not even the cost. It is the technology issues of high sampling rates such as the necessity of high-rate Analog-to-Digital (A/D) converters. The reduction in sampling rate can be achieved using Compressive Sensing (CS) or, in a much simpler form, Random Sampling (RS). In CS, we take a number of linear combinations of sparse... 

Twitter as one of the most important microblogging online social networks has attracted more than 200 million users in recent years. Although there have been several attempts on characterizing the Twitter by using incomplete sampled data, they have not been very successful to estimate the characteristics of the whole network. In this paper, we characterize Twitter by sampling from its social graph and user behaviors through a random walk based sampling technique called Respondent-Driven Sampling (RDS). To the best of our knowledge, for the first time RDS method and its estimator are used in order to obtain uniform unbiased estimation of several key structural and behavioral properties of... 

In this paper, we analyze the basic principles of the spread-space holographic code division multiple access (CDMA) technique. We describe the structure of the encoder and decoder and present a basic mathematical analysis based on spatial harmonic decomposition for the receiver's processing module, which is comprised of a Fourier transform lens and a holographic matched filter. Subsequently, we study two applications of optical holographic CDMA, namely, free-space holographic CDMA photonic switch and free-space (wireless) multiaccess optical (infrared) indoor communications. For both techniques, we describe the two-dimensional imaging techniques, namely user's code transmission, and... 

In this paper we study an application of optical Holographic CDMA for free-space (wireless) optical (infrared) indoor communications. First, we describe the principles of the spread-space Holographic CDMA indicating the structure of the encoder and decoder and describe mathematically the receiver's processing module which is comprised of a Fourier transform lens and a holographic matched-filter. Then, we study the performance of an indoors infrared communication link using spot-diffused configuration. Free-space optical Holographic CDMA processing gain (PG) can in principle be as high as 106-108 and each user can have different modulating signals (Analog or Digital), or different information... 

The operational range of microcantilever beams under electrostatic force can be extended beyond pull-in in the presence of an intermediate dielectric layer. In this paper, a systematic method for deriving dynamic equation of microcantilevers under electrostatic force is presented. This model covers the behavior of the microcantilevers before and after the pull-in including the effects of van der Waals force, squeeze-film damping, and contact bounce. First, a polynomial approximate shape function with a time-dependent variable for each configuration is defined. Using Hamilton's principle, dynamic equations of microcantilever in all configurations have been derived. Comparison between modeling... 

In this paper, a comprehensive model is used to describe dynamic behavior of SDA and its components during stepwise motion. In this model, Hamilton’s principle and Newton's method are used to extract dynamic equations of the SDA plate and dynamic equation for the linear motion of SDA. Comparison between the modeling results and available experimental data shows that this model is very effective in predicting some design objectives such as step size and output force for this type of actuators  

Microcantilever beams are frequently utilized in microelectromechanical systems. The operational range of microcantilever beams under electrostatic force can be extended beyond pull-in in the presence of an intermediate dielectric layer, which has a significant effect on the behavior of the system. Three possible configurations of the beam over the operational voltage range are floating, pinned, and flat configurations. In this paper, a systematic method for deriving dynamic equation of microcantilevers for all configurations is presented. First, a static study is performed on deflection profile of the microcantilever under electrostatic force. After that, a polynomial approximate shape... 

There has been much research in developing scratch drive actuators (SDAs), but because of their dynamic complexity, these microelectromechanical system-based actuators have not been dynamically analyzed up to now. In this paper, a comprehensive model is presented to describe the dynamic behavior of SDA and its components during stepwise motion. In this model, Hamilton's principle and Newton's method are used to extract dynamic equations of the SDA plate and dynamic equation for the linear motion of SDA. This model presents a good insight into the operating principles of SDA by predicting the variation of different variables, such as bushing angle, contact length, horizontal position, and... 

In this paper, a Block Iterative Method with Adaptive Thresholding for Sparse Recovery (BIMATSR) is proposed to recover the received signal in an under-sampled distributed multiple-input multiple-output radar. The BIMATSR scheme induces block sparsity with the aid of a signal-dependent thresholding operator which increases the accuracy of the target parameter estimation task. We have proved that under some sufficient conditions, the suggested scheme converges to a stable solution. Moreover, different simulation scenarios confirm that the BIMATSR algorithm outperforms its counterparts in terms of the target parameter estimation. This superiority is achieved at the expense of slightly more... 

In this paper, a Block Iterative Method with Adaptive Thresholding for Sparse Recovery (BIMATSR) is proposed to recover the received signal in an under-sampled distributed MIMO radar. The BIMATSR scheme induces block sparsity with the aid of a signal-dependent thresholding operator which increases the accuracy of the target parameter estimation task. We have proved that under some sufficient conditions, the suggested scheme converges to a stable solution. Moreover, different simulation scenarios confirm that the BIMATSR algorithm outperforms its counterparts in terms of the target parameter estimation. This superiority is achieved at the expense of slightly more computational complexity. It...