Sobol Sequence Optimization for Hardware-Efficient Vector Symbolic Architectures

Hyperdimensional computing (HDC) is an emerging computing paradigm with significant promise for efficient and robust learning. In HDC, objects are encoded with high-dimensional vector symbolic sequences called hypervectors. The quality of hypervectors, defined by their distribution and independence, directly impacts the performance of HDC systems. Despite a large body of work on the processing parts of HDC systems, little to no attention has been paid to data encoding and the quality of hypervectors. Most prior studies have generated hypervectors using inherent random functions, such as MATLAB`s or Python`s random function. This work introduces an optimization technique for generating hypervectors by employing quasi-random sequences. These sequences have recently demonstrated their effectiveness in achieving accurate and low-discrepancy data encoding in stochastic computing systems. The study outlines the optimization steps for utilizing Sobol sequences to produce high-quality hypervectors in HDC systems. An optimization algorithm is proposed to select the most suitable Sobol sequences for generating minimally correlated hypervectors, particularly in applications related to symbol-oriented architectures. The performance of the proposed technique is evaluated in comparison to two traditional approaches of generating hypervectors based on linear-feedback shift registers and MATLAB random function. The evaluation is conducted for two applications: (i) language and (ii) headline classification. Our experimental results demonstrate accuracy improvements of up to 10.79%, depending on the vector size. Additionally, the proposed encoding hardware exhibits reduced energy consumption and a superior area-delay product.Comment: 9 pages, 7 figure

Density-dependent analytical equations of radiation shielding parameters for super alloys by linear regression analysis

Super alloys have great interest with good mechanical strength, surface stability, high operating temperatures, and high resistance to corrosion and oxidation features. In the study, new, reliable, and practical equations which give the radiation shielding parameters depending on the density of super alloys are obtained. For this analysis, MAR-247, MAR 302, Inconel 625, Inconel 718, Nimocast 75, WI-52, Inconel 617, Incoloy 800HT, Inconel 939, 713LC, and 7925A super alloys are chosen. The radiation shielding parameters such as linear attenuation coefficient, effective atomic number, half value layer, mean free path, and fast neutron removal cross-section are calculated by using Phy-X/PSD program. Then, new analytical equations providing the radiation shielding parameters by linear regression analysis are evaluated

On the direct limit from pseudo-Jacobi polynomials to Hermite polynomials

In this short communication, we present a new limit relation that reduces pseudo-Jacobi polynomials directly to Hermite polynomials. The proof of this limit relation is based upon 2F1-type hypergeometric transformation formulas, which are applicable to even and odd polynomials separately. This limit opens the way to studying new exactly solvable harmonic oscillator models in quantum mechanics in terms of pseudo-Jacobi polynomials

A Novel DTC Method with Efficiency Improvement of IM for EV Applications

Induction motor (IM) stator flux optimization is very important in order to get increasing running distance per battery charge of electric vehicles (EVs). This study introduces a new direct torque control (DTC) method for efficiency improvement of IM in EV applications. Also, it is proposed to decrease the torque ripple of DTC based IM. Generally, loss minimization algorithms can be simplified by neglecting the core loss or the effect of leakage inductance in the motor model. However, neglecting the core loss causes an error in torque control of DTC. Beside this, exact loss minimization cannot be achieved since a large voltage drop across leakage inductance occurs especially in high-speed region. In the proposed method, the motor model is simplified by neglecting the current in the core loss resistance branch instead of neglecting the core loss and the effect of leakage inductance. The proposed method is simulated in Matlab for variable speeds and loads. Results show that it provides a significant reduction of losses and decreases the torque ripple of IM drives

Amyloid-like peptide nanofiber templated titania nanostructures as dye sensitized solar cell anodic materials

Cataloged from PDF version of article.One-dimensional titania nanostructures can serve as a support for light absorbing molecules and result in an improvement in the short circuit current (Jsc) and open circuit voltage (Voc) as a nanostructured and high-surface-area material in dye-sensitized solar cells. Here, self-assembled amyloid-like peptide nanofibers were exploited as an organic template for the growth of one-dimensional titania nanostructures. Nanostructured titania layers were utilized as anodic materials in dye sensitized solar cells (DSSCs). The photovoltaic performance of the DSSC devices was assessed and an enhancement in the overall cell performance compared to unstructured titania was observed. © 2013 The Royal Society of Chemistry