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Middle East Technical University Journal of the Faculty of Architecture , 2011,
Efficient Sampling of Band-limited Signals from Sine Wave Crossings
J. Selva
Mathematics , 2010,
Abstract: This correspondence presents an efficient method for reconstructing a band-limited signal in the discrete domain from its crossings with a sine wave. The method makes it possible to design A/D converters that only deliver the crossing timings, which are then used to interpolate the input signal at arbitrary instants. Potentially, it may allow for reductions in power consumption and complexity in these converters. The reconstruction in the discrete domain is based on a recently-proposed modification of the Lagrange interpolator, which is readily implementable with linear complexity and efficiently, given that it re-uses known schemes for variable fractional-delay (VFD) filters. As a spin-off, the method allows one to perform spectral analysis from sine wave crossings with the complexity of the FFT. Finally, the results in the correspondence are validated in several numerical examples.
FFT Interpolation from Nonuniform Samples Lying in a Regular Grid
J. Selva
Mathematics , 2014,
Abstract: This paper presents a method to interpolate a periodic band-limited signal from its samples lying at nonuniform positions in a regular grid, which is based on the FFT and has the same complexity order as this last algorithm. This kind of interpolation is usually termed "the missing samples problem" in the literature, and there exists a wide variety of iterative and direct methods for its solution. The one presented in this paper is a direct method that exploits the properties of the so-called erasure polynomial, and it provides a significant improvement on the most efficient method in the literature, which seems to be the burst error recovery (BER) technique of Marvasti's et al. The numerical stability and complexity of the method are evaluated numerically and compared with the pseudo-inverse and BER solutions.
Signal Estimation from Nonuniform Samples with RMS Error Bound -- Application to OFDM Channel Estimation
J. Selva
Mathematics , 2014,
Abstract: We present a channel spectral estimator for OFDM signals containing pilot carriers, assuming a known delay spread or a bound on this parameter. The estimator is based on modeling the channel's spectrum as a band-limited function, instead of as the discrete Fourier transform of a tapped delay line (TDL). Its main advantage is its immunity to the truncation mismatch in usual TDL models (Gibbs phenomenon). In order to assess the estimator, we compare it with the well-known TDL maximum likelihood (ML) estimator in terms of root-mean-square (RMS) error. The main result is that the proposed estimator improves on the ML estimator significantly, whenever the average spectral sampling rate is above the channel's delay spread. The improvement increases with the spectral oversampling ratio.
Regularized sampling of multiband signals
J. Selva
Mathematics , 2010, DOI: 10.1109/TSP.2010.2057248
Abstract: This paper presents a regularized sampling method for multiband signals, that makes it possible to approach the Landau limit, while keeping the sensitivity to noise at a low level. The method is based on band-limited windowing, followed by trigonometric approximation in consecutive time intervals. The key point is that the trigonometric approximation "inherits" the multiband property, that is, its coefficients are formed by bursts of non-zero elements corresponding to the multiband components. It is shown that this method can be well combined with the recently proposed synchronous multi-rate sampling (SMRS) scheme, given that the resulting linear system is sparse and formed by ones and zeroes. The proposed method allows one to trade sampling efficiency for noise sensitivity, and is specially well suited for bounded signals with unbounded energy like those in communications, navigation, audio systems, etc. Besides, it is also applicable to finite energy signals and periodic band-limited signals (trigonometric polynomials). The paper includes a subspace method for blindly estimating the support of the multiband signal as well as its components, and the results are validated through several numerical examples.
Efficient Maximum Likelihood Estimation of a 2-D Complex Sinusoidal Based on Barycentric Interpolation
J. Selva
Mathematics , 2011,
Abstract: This paper presents an efficient method to compute the maximum likelihood (ML) estimation of the parameters of a complex 2-D sinusoidal, with the complexity order of the FFT. The method is based on an accurate barycentric formula for interpolating band-limited signals, and on the fact that the ML cost function can be viewed as a signal of this type, if the time and frequency variables are switched. The method consists in first computing the DFT of the data samples, and then locating the maximum of the cost function by means of Newton's algorithm. The fact is that the complexity of the latter step is small and independent of the data size, since it makes use of the barycentric formula for obtaining the values of the cost function and its derivatives. Thus, the total complexity order is that of the FFT. The method is validated in a numerical example.
The In-Terrorem Value of Science: Bisphenol-A Litigation and an Empirical Assessment of Science as a Collective Litigation Tool  [PDF]
Suman Kakar, Sanjeev Sirpal
Beijing Law Review (BLR) , 2011, DOI: 10.4236/blr.2011.22006
Abstract: This paper examines the role that science plays as a tool in collective litigation to substantiate claims. Scientific data and expert testimony are often included to buttress a claim and the admissibility of such evidence is often a conse-quence of the extant evidentiary rules and their application. The article will focus on the multidistrict litigation con-cerning Bisphenol-A (“BPA”) as a case study of the phenomena of scientific tailoring of evidence and its admissibility. BPA is a compound included in the synthesis of plastics and is found in food containers, plastic bottles, and ep-oxy-based coatings used to avert the rusting process of food containers. There is a negligible amount of BPA in several food and beverage products. Several countries along with the US Food and Drug Administration (FDA) and Environ-mental Protection Agency (EPA) have marshaled scientific studies that demonstrate the lack of any definable negative health effect attributable to an exposure to trace amounts of BPA. Notwithstanding the conclusions of these scientific inquiries, opponents have asserted that BPA exposure results in an alteration of embryonic hormone levels, thereby impacting their development and later reproductive function. This article will address these issues in addition to the salient question of what role science plays as a tool for collective litigation.
Application of Cross-Plotting Techniques for Delineation of Coal and Non-Coal Litho-Units from Well Logs  [PDF]
Rima Chatterjee, Suman Paul
Geomaterials (GM) , 2012, DOI: 10.4236/gm.2012.24014
Abstract: Well log responses can be used to delineate coal and carbonaceous shale from other non-potential litho-units by cross-plotting technique. The cross-plotting between gamma ray and density had been carried out for 15 wells of Jharia coalfield, India. Through these different cross-plots across the study area, different litho-units like; coal, shaly coal, carbonaceous shale, shale, sand/sandstone, shaly sand, jhama and igneous intrusion (mica peridotite) have been identified. Clustering of points for different lithologies in the above cross-plots indicate that the different trends with marginal overlap between carbonaceous shale/shaly coal and shale as well as shaly sand and shale. The coal horizons are mostly overlain and underlain by shale or sandstone. Cross-plot analysis indicates the various coal lithologies which will play important role in CBM exploration and exploitation strategy.
Energy Aware Processor Architecture for Effective Scheduling and Power Management in Cloud Using Inclusive Power-Cognizant Processor Controller  [PDF]
Suma Sira Jacob, C. Kezi Selva Vijila
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78157
Abstract: The fast acceptance of cloud technology to industry explains increasing energy conservation needs and adoption of energy aware scheduling methods to cloud. Power consumption is one of the top of mind issues in cloud, because the usage of cloud storage by the individuals or organization grows rapidly. Developing an efficient power management processor architecture has gained considerable attention. However, the conventional power management mechanism fails to consider task scheduling policies. Therefore, this work presents a novel energy aware framework for power management. The proposed system leads to the development of Inclusive Power-Cognizant Processor Controller (IPCPC) for efficient power utilization. To evaluate the performance of the proposed method, simulation experiments inputting random tasks as well as tasks collected from Google Trace Logs were conducted to validate the supremacy of IPCPC. The research based on Real world Google Trace Logs gives results that proposed framework leads to less than 9% of total power consumption per task of server which proves reduction in the overall power needed.
Profit from Sickness: The Case of Technology-Driven Healthcare  [PDF]
Suman Hazarika, Akhil Ranjan Dutta
Advances in Applied Sociology (AASoci) , 2012, DOI: 10.4236/aasoci.2012.24031
Abstract: The increasing corporatization and growing dependence of the healthcare system on technology has brought about a radical transformation to the entire mission of the healthcare system. Based on the profit motive, the pharmaceutical and technological enterprises that hugely control the healthcare system today have so transformed the system that it has now emerged as one of the most profiteering domains. The historical tragedy is that the profit is earned over sickness. There has indeed been an attempt to generate sickness as demanded both by health care devices as well as by the pharmaceutical industries having detrimental impact on people’s right to health. Present paper, which critically questions the logic and motives of the emerging healthcare system, argues that under the contemporary neo-liberal economies, diseases and patients are objects of business interests of the largely privatized for-profit healthcare industry. Profit from these objects emerges not only through sale of drugs or cure, but also from expensive hi-tech testing and ‘treatment’ technologies. Creation of new patients by diagnosing more diseases to treat is contributed by a large medical-industrial complex today. The paper is of the view that remedies to these crises demand radical a U-turn to the system itself wherein the health care seekers rather than the health care providers would occupy the center stage.
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