A New Blind DOA Estimation Using Two Uniform Linear Array for Low Side Lobe Adaptive Array

312-314Suitably designed Adaptive algorithm can collect the main signals’ multipath and add them constructively with main signal with very low side lobe level in all other directions, hence eliminating the jamming signal from other directions. A new technique for DOA estimation of signals impinging on Two Uniform Linear Array (ULA) offset with each other by a known angle also has been proposed for further analysis and discussions

Spatially varying fuzzy multi-scale uncertainty propagation in unidirectional fibre reinforced composites

SN and SS are grateful for the support provided through the Lloyd’s Register Foundation Centre. The Foundation helps to protect life and property by supporting engineering-related education, public engagement and the application of research.Peer reviewedPostprin

On higher dimensional Poissonian pair correlation

In this article we study the pair correlation statistic for higher dimensional sequences. We show that for any $d\geq 2$, strictly increasing sequences $(a_n^{(1)}),\ldots, (a_n^{(d)})$ of natural numbers have metric Poissonian pair correlation with respect to sup-norm if their joint additive energy is $O(N^{3-\delta})$ for any $\delta>0$. Further, in two dimension, we establish an analogous result with respect to $2$-norm. As a consequence, it follows that $(\{n\alpha\}, \{n^2\beta\})$ and $(\{n\alpha\}, \{[n\log^An]\beta\})$ ($A \in [1,2]$) have Poissonian pair correlation for almost all $(\alpha,\beta)\in \mathbb{R}^2$ with respect to sup-norm and $2$-norm. This gives a negative answer to the question raised by Hofer and Kaltenb\"ock [15]. The proof uses estimates for 'Generalized' GCD-sums.Comment: Added references and corrected typos. To appear in Journal of Mathematical Analysis and Application

Size-dependent dynamic characteristics of graphene based multi-layer nano hetero-structures

Carbon-based nano hetero-structures are receiving increasing attention due their ability in multi-synchronous modulation of a range of mechanical and other critically desirable properties. In this paper, the vibration characteristics of two different graphene based heterostructures, graphene-hexagonal boron nitride (hBN) and graphene-molybdenum disulfide (MoS2), are explored based on atomistic finite element approach. Such vibrational characteristics of nanostructures are of utmost importance in order to access their suitability as structural members for adoption in various nano-scale devices and systems. In the current analysis, the developed atomistic finite element model for nano-heterostructures is extensively validated first with the results available in literature considering elastic responses and natural frequencies. Thereafter a range of insightful new results are presented for the dynamic behaviour of various configurations of graphene-hBN and graphene-MoS2 heterostructures including their size, chirality and boundary dependence. The investigation of tunable vibrational properties along with simultaneous modulation of other mechanical, electronic, optical, thermal and chemical attributes of such nano-heterostructures would accelerate their application as prospective candidates for manufacturing nanosensors, electromechanical resonators, and a wide range of other devices and systems across the length-scales

A New Blind DOA Estimation Using Two Uniform Linear Array for Low Side Lobe Adaptive Array

Suitably designed Adaptive algorithm can collect the main signals’ multipath and add them constructively with main signal with very low side lobe level in all other directions, hence eliminating the jamming signal from other directions. A new technique for DOA estimation of signals impinging on Two Uniform Linear Array (ULA) offset with each other by a known angle also has been proposed for further analysis and discussions

Assessment of drug utilization pattern and rationality of drug use in treatment of dilated cardiomyopathy in a tertiary care teaching hospital of rural Bengal

Background: Dilated cardiomyopathy (DCM) is an important underlying cause of congestive heart failure and/or arrhythmias. The introduction of therapy combining diuretics, digoxin and angiotensin converting enzyme inhibitors (ACEI) has significantly decreased mortality and morbidity. The aim of the study was undertaken to identify the pattern of drugs most commonly prescribed for DCM and to assess the rationality behind such use.Methods: This was a prospective study undertaken between 1st July and 31st August 2015. Prescriptions were reviewed and analyzed using the World Health Organization (WHO) indicators for drug utilization studies. Rationality and cost of therapy per prescription was also evaluated.Results: We encountered 78 patients of DCM in the OPD of Cardiology (prevalence of 4.94%). The average number of drugs per prescription was 6.64. Generic prescriptions were made in 90% encounters. As part of therapy, diuretics and ACE inhibitors or angiotensin receptor blockers, were prescribed in all cases. Our results show a distinctive drug use pattern where beta blockers were used more commonly than digoxin. Other commonly prescribed agents were antiplatelet drugs and statins. Antibiotics were prescribed in 8.7% cases and no injectable drug was prescribed. Average drug cost per encounter was 10.63 INR.Conclusions: To conclude, we found a typical and rational pattern of drug use. Diuretics, ACEI and beta blockers were found to be most commonly used agents. This study provides a clear picture of drug use in this special clinical condition in rural Bengal and paves the way for larger and long term studies

Programmable stiffness and shape modulation in origami materials: Emergence of a distant actuation feature

This paper develops an origami based mechanical metamaterial with programmable deformation-dependent stiffness and shape modulation, leading to the realization of a distant actuation feature. Through computational and experimental analyses, we have uncovered that a waterbomb based tubular metamaterial can undergo mixed mode of deformations involving both rigid origami motion and structural deformation. Besides the capability of achieving a near-zero stiffness, a contact phase is identified that initiates a substantial increase in the stiffness with programmable features during deformation of the metamaterial. Initiation of the contact phase as a function of the applied global load can be designed based on the microstructural geometry of the waterbomb bases and their assembly. The tubular metamaterial can exhibit a unique deformation dependent spatially varying mixed mode Poisson’s ratio, which is achievable from a uniform initial configuration of the metamaterial. The spatial profile of the metamaterial can be modulated as a function of the applied far-field global force, and the configuration and assembly of the waterbomb bases. This creates a new possibility of developing a distant actuation feature in the metamaterial enabling us to achieve controlled local actuation through the application of a single far-field force. The distant actuation feature eliminates the need of installing embedded complex network of sensors, actuators and controllers in the material. The fundamental programmable features of the origami metamaterial unravelled in this paper can find wide range of applications in soft robotics, aerospace, biomedical devices and various other advanced physical systems

Gaussian process assisted stochastic dynamic analysis with applications to near-periodic structures

This paper characterizes the stochastic dynamic response of periodic structures by accounting for manufacturing variabilities. Manufacturing variabilities are simulated through a probabilistic description of the structural material and geometric properties. The underlying uncertainty propagation problem has been efficiently carried out by functional decomposition in the stochastic space with the help of Gaussian Process (GP) meta-modelling. The decomposition is performed by projected the response onto the eigenspace and involves a nominal number of actual physics-based function evaluations (the eigenvalue analysis). This allows the stochastic dynamic response evaluation to be solved with low computational cost. Two numerical examples, namely an analytical model of a damped mechanical chain and a finite-element model of multiple beam-mass systems, are undertaken. Two key findings from the results are that the proposed GP based approximation scheme is capable of (i) capturing the stochastic dynamic response in systems with well-separated modes in the presence of high levels of uncertainties (up to 20), and (ii) adequately capturing the stochastic dynamic response in systems with multiple sets of identical modes in the presence of 5–10 uncertainty. The results are validated by Monte Carlo simulations

A multivariate adaptive regression splines based damage identification methodology for web core composite bridges including the effect of noise

A novel computationally efficient damage identification methodology for web core fiber-reinforced polymer composite bridges has been developed in this article based on multivariate adaptive regression splines in conjunction with a multi-objective goal-attainment optimization algorithm. The proposed damage identification methodology has been validated for several single and multiple damage cases. The performance of the efficient multivariate adaptive regression splines-based approach for the inverse system identification process is found to be quite satisfactory. An iterative scheme in conjunction with the multi-objective optimization algorithm coupled with multivariate adaptive regression splines is proposed to increase damage identification accuracy. The effect of noise on the proposed damage identification algorithm has also been addressed subsequently using a probabilistic framework. The multivariate adaptive regression splines-based damage identification algorithm is general in nature; therefore, in future it can be implemented to other structures.</p

On-demand contactless programming of nonlinear elastic moduli in hard magnetic soft beam based broadband active lattice materials

Engineered honeycomb lattice materials with high specific strength and stiffness along with the advantage of programmable direction-dependent mechanical tailorability are being increasingly adopted for various advanced multifunctional applications. To use these artificial microstructures with unprecedented mechanical properties in the design of different application-specific structures, it is essential to investigate the effective elastic moduli and their dependence on the microstructural geometry and the physics of deformation at the elementary level. While it is possible to have a wide range of effective mechanical properties based on their designed microstructural geometry, most of the recent advancements in this field lead to passive mechanical properties, meaning it is not possible to actively modulate the lattice-level properties after they are manufactured. Thus the on-demand control of mechanical properties is lacking, which is crucial for a range of multi-functional applications in advanced structural systems. To address this issue, we propose a new class of lattice materials wherein the beam-level multi-physical deformation behavior can be exploited as a function of external stimuli like magnetic field by considering hard magnetic soft beams. More interestingly, effective property modulation at the lattice level would be contactless without the necessity of having a complex network of electrical circuits embedded within the microstructure. We have developed a semi-analytical model for the nonlinear effective elastic properties of such programmable lattice materials under large deformation, wherein the mechanical properties can be modulated in an expanded design space of microstructural geometry and magnetic field. The numerical results show that the effective properties can be actively modulated as a function of the magnetic field covering a wide range (including programmable state transition with on-demand positive and negative values), leading to the behavior of soft polymer to stiff metals in a single lattice microstructure according to operational demands