Convolutional compressed sensing using deterministic sequences

This is the author's accepted manuscript (with working title "Semi-universal convolutional compressed sensing using (nearly) perfect sequences"). The final published article is available from the link below. Copyright @ 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, a new class of orthogonal circulant matrices built from deterministic sequences is proposed for convolution-based compressed sensing (CS). In contrast to random convolution, the coefficients of the underlying filter are given by the discrete Fourier transform of a deterministic sequence with good autocorrelation. Both uniform recovery and non-uniform recovery of sparse signals are investigated, based on the coherence parameter of the proposed sensing matrices. Many examples of the sequences are investigated, particularly the Frank-Zadoff-Chu (FZC) sequence, the m-sequence and the Golay sequence. A salient feature of the proposed sensing matrices is that they can not only handle sparse signals in the time domain, but also those in the frequency and/or or discrete-cosine transform (DCT) domain

Dual-lattice ordering and partial lattice reduction for SIC-based MIMO detection

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2009 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, we propose low-complexity lattice detection algorithms for successive interference cancelation (SIC) in multi-input multi-output (MIMO) communications. First, we present a dual-lattice view of the vertical Bell Labs Layered Space-Time (V-BLAST) detection. We show that V-BLAST ordering is equivalent to applying sorted QR decomposition to the dual basis, or equivalently, applying sorted Cholesky decomposition to the associated Gram matrix. This new view results in lower detection complexity and allows simultaneous ordering and detection. Second, we propose a partial reduction algorithm that only performs lattice reduction for the last several, weak substreams, whose implementation is also facilitated by the dual-lattice view. By tuning the block size of the partial reduction (hence the complexity), it can achieve a variable diversity order, hence offering a graceful tradeoff between performance and complexity for SIC-based MIMO detection. Numerical results are presented to compare the computational costs and to verify the achieved diversity order

Profiles, Use, and Perceptions of Singapore Multiple Credit Cardholders

This study analyzes Singapore’s diverse cardholders in search of variations among demographic groups, credit card profiles, and their perceptions with regards to credit card ownership and use, it then discusses possible reasons governing Singaporeans’ credit card ownership and use. A survey was conducted (n = 636), decision trees were then constructed using Chi-square automatic interaction detection algorithm (CHAID) and SPSS software AnswerTree to examine the association between the number of credit cards (target variable) and the demographic characteristics, perceptions and other credit card related variables. The number of credit cards was found to be significantly influenced by income and gender as well as perceptions that include “credit card leads to overspending”, “savings as payment source”, “unreasonable interest rates”, “credit card as status symbol”. The number of credit cards was also affected by credit card related variables such as missing payments sometimes, frequency of use, entertainment expenditures, and petrol purchase. This research provides an in-depth understanding of Singaporean multiple cardholders, thus it is useful in designing marketing strategies for card-issuers as well as anti-debt strategies for policy-makers in Singapore. Despite the importance of consumer credit, virtually no literature or research exists on the ownership and use of credit cards in Singapore, so this paper intends to close this gap. Further, by combining the demographics, cardholders’ profiles and usage patterns with the respondents’ perceptions concerning credit card ownership and use, our study offers a richer analysis to explain consumer behavior than previous literatures.Credit card ownership, credit card use, credit revolving, credit debts, decision tree, Singapore

Positive exchange bias in ferromagnetic La0.67Sr0.33MnO3 / SrRuO3 bilayers

Epitaxial La0.67Sr0.33MnO3 (LSMO)/ SrRuO3 (SRO) ferromagnetic bilayers have been grown on (001) SrTiO3 (STO) substrates by pulsed laser deposition with atomic layer control. We observe a shift in the magnetic hysteresis loop of the LSMO layer in the same direction as the applied biasing field (positive exchange bias). The effect is not present above the Curie temperature of the SRO layer (), and its magnitude increases rapidly as the temperature is lowered below . The direction of the shift is consistent with an antiferromagnetic exchange coupling between the ferromagnetic LSMO layer and the ferromagnetic SRO layer. We propose that atomic layer charge transfer modifies the electronic state at the interface, resulting in the observed antiferromagnetic interfacial exchange coupling.Comment: accepted to Applied Physics Letter

Impact of hedging pressure on implied volatility in Financial Times and London Stock Exchange (FTSE) market

This paper examines the impact of net buying pressure and the event of 9/11 on the implied volatility of the U.K. FTSE 100 (Financial Times and the London Stock Exchange) index options. Our findings indicate that when effects such as financial leverage, information flow and mean reversion are held constant, the net buying pressure of the out-of-the-money put options plays a dominant role in determining the shape of the implied volatility function. Further, the event of 9/11 has a transitory influence on the implied volatility change. Our results also support the notion that hedging pressure can help explain the difference between implied volatility and realized volatility

A Particle Image Velocimetry study of dual-rotor counter-rotating wind turbine near wake

This experimental work studied the flow characteristics in the near wake region behind dual-rotor wind turbines using two-dimensional particle image velocimetry. Two auxiliary rotors of 50% and 80% scale of the main rotor were installed upwind and operated in counter-rotating condition, which are compared to the conventional single rotor turbine. In all the three configurations, a constant Reynolds number 9.5×104 was applied and all the rotors operated at a fixed tip speed ratio of 3.46. The mean and phase averaged velocity fields were investigated together with the turbulence kinetic energy. It was found that the two auxiliary rotors do not result in a significantly different wake flow property. The configuration implementing the 50% auxiliary rotor sees a slightly better wake characteristics, in terms of weaker main rotor tip vortices and a counter-rotating swirling shear region at the mid-span behind the main rotor. The decay rates of the peak vorticity of the main rotor tip vortices and their circulation are found to follow an exponential manner

Distribution of Capillary Transit Times in Isolated Lungs of Oxygen-Tolerant Rats

Rats pre-exposed to 85% O2 for 5–7 days tolerate the otherwise lethal effects of 100% O2. The objective was to evaluate the effect of rat exposure to 85% O2 for 7 days on lung capillary mean transit time (t¯c) and distribution of capillary transit times (h c(t)). This information is important for subsequent evaluation of the effect of this hyperoxia model on the redox metabolic functions of the pulmonary capillary endothelium. The venous concentration vs. time outflow curves of fluorescein isothiocyanate labeled dextran (FITC-dex), an intravascular indicator, and coenzyme Q1 hydroquinone (CoQ1H2), a compound which rapidly equilibrates between blood and tissue on passage through the pulmonary circulation, were measured following their bolus injection into the pulmonary artery of isolated perfused lungs from rats exposed to room air (normoxic) or 85% O2 for 7 days (hyperoxic). The moments (mean transit time and variance) of the measured FITC-dex and CoQ1H2 outflow curves were determined for each lung, and were then used in a mathematical model [Audi et al. J. Appl. Physiol. 77: 332–351, 1994] to estimate t¯c and the relative dispersion (RDc) of h c(t). Data analysis reveals that exposure to hyperoxia decreases lung t¯c by 42% and increases RDc, a measure h c(t) heterogeneity, by 40%

Post-harvest soil water and N status in pulse fields in comparison to chem-fallow

Non-Peer Reviewe

Superconducting Pairing Symmetries in Anisotropic Triangular Quantum Antiferromagnets

Motivated by the recent discovery of a low temperature spin liquid phase in layered organic compound $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$ which becomes a superconductor under pressure, we examine the phase transition of Mott insulating and superconducting (SC) states in a Hubbard-Heisenberg model on an anisotropic triangular lattice. We use a renormalized mean field theory to study the Gutzwiller projected BCS wavefucntions. The half filled electron system is a Mott insulator at large on-site repulsion $U$, and is a superconductor at a moderate $U$. The symmetry of the SC state depends on the anisotropy, and is gapful with $d_{x^2-y^2}+id_{xy}$ symmetry near the isotropic limit and is gapless with $d_{x^2-y^2}$ symmetry at small anisotropy ratio.Comment: 6 pages, 5 figure