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Synthetic aperture radar (SAR) at the terahertz (THz) spectrum has emerging short-range applications. In comparison to the microwave spectrum, the THz spectrum is limited in propagation range but benefits from high spatial resolution. The THz SAR is of significant interest for several applications which necessitate the mapping of indoor environments to support various endeavors such as rescue missions, map-assisted wireless communications, and household robotics. This paper addresses the augmentation of the high-resolution indoor mapped environment for object recognition, which includes detection, localization, and classification. Indoor object recognition is currently dominated by the usage of optical and infrared (IR) systems. However, it is not widely explored by radar technologies due to the limited spatial resolution at the most commonly used microwave frequencies. However, the THz spectrum provides a new paradigm of possible adaptation of object recognition in the radar domain by providing image quality in good compliance to optical/IR systems. In this paper, a multi-object indoor environment is foremost mapped at the THz spectrum ranging from 325 to 500 GHz in order to investigate the imaging in highly scattered environments and accordingly create a foundation for detection, localization, and classification. Furthermore, the extraction and clustering of features of the mapped environment are conducted for object detection and localization. Finally, the classification of detected objects is addressed with a supervised machine learning-based support vector machine (SVM) model.

This paper introduces a new endurance equation for a hybrid-electric aircraft. This research follows the derivation of a range equation for a hybrid-electric aircraft case using constant power split that was carried out by authors in their earlier work. Thus, the derivation of the endurance equation maintains the use of efficiency-based degree of hybridization (φ) used in the earlier research. For coherence, the paper also uses the same case study to assess endurance values over a range of battery energy density values and degree of hybridization (φ) values. Results show that any aircraft design has an Energy Density Threshold (EDT) value, before which the endurance of the aircraft reduces with an increase in the degree of hybridization values. Conversely, once EDT is exceeded, the endurance of the aircraft enhances with the increase in the degree of hybridization values. The EDT values are specific to the aircraft type, its specifications and key design parameters.

Time-domain backprojection algorithms are widely used in state-of-the-art synthetic aperture radar (SAR) imaging systems that are designed for applications where motion error compensation is required. These algorithms include an interpolation procedure, under which an unknown SAR range-compressed data parameter is estimated based on complex-valued SAR data samples and backprojected into a defined image plane. However, the phase of complex-valued SAR parameters estimated based on existing interpolators does not contain correct information about the range distance between the SAR imaging system and the given point of space in a defined image plane, which affects the quality of reconstructed SAR scenes. Thus, a phase-control procedure is required. This paper introduces extensions of existing linear, cubic, and sinc interpolation algorithms to interpolate complex-valued SAR data, where the phase of the interpolated SAR data value is controlled through the assigned a priori known range time that is needed for a signal to reach the given point of the defined image plane and return back. The efficiency of the extended algorithms is tested at the Nyquist rate on simulated and real data at THz frequencies and compared with existing algorithms. In comparison to the widely used nearest-neighbor interpolation algorithm, the proposed extended algorithms are beneficial from the lower computational complexity perspective, which is directly related to the offering of smaller memory requirements for SAR image reconstruction at THz frequencies.

This paper proposes a new range equation for hybrid-electric aircraft. The paper revisits the theory of the range equation for a hybrid-electric aircraft with constant power split published earlier in the literature and proposes a new efficiency-based definition of the degree of hybridization (φ), one which includes the efficiencies of the electric or fuel-powered drivetrain. The paper shows that the efficiencies of the respective drivetrains play a significant role in the range estimation of the hybrid-electric aircraft. The paper makes use of a case study to show the relationship between battery energy density, powertrain efficiency and modification in the definition of the degree of hybridization φ with aircraft range. We show that for every aircraft design, there is a battery energy density threshold, for which the aircraft range becomes independent of the degree of hybridization. Below this threshold, the range decreases with an increase in the degree of hybridization. Conversely, beyond this threshold, the aircraft range increases with the degree of hybridization. Our study finds that the new definition of φ has shifted this threshold significantly upwards compared to earlier publications in the literature. This makes the design of an aircraft with a high degree of hybridization less optimistic.

This paper proposes a novel single-layer, low-profile harmonic transponder to be integrated with the printable diodes based on Si particles. The introduced prototype consists of two bowtie dipoles that are directly matched to the harmonic generation element at a fundamental 2.45GHz frequency and also at the corresponding second harmonic 4.9GHz frequency. Therefore, the antennas and T-matching parts can be manufactured as separate inlays using a single layer-substrate. Besides the new prototype, the harmonic conversion loss (CL) is theoretically and experimentally investigated. In this regard, the equivalent circuit is driven and utilized to analyze the CL performance with variations in fundamental frequency and input power. The introduced transponder outperforms the state-of-the-art work from the printability, size, and CL point of views.

Consider a non-uniform Euler-Bernoulli beam with a tip-mass at one end and a cantilever joint at the other end. The cantilever joint is not fixed and can itself be moved along an axis perpendicular to the beam. The position of the cantilever joint is the control input to the beam. The dynamics of the beam is governed by a coupled PDE-ODE model with boundary input. On a natural state-space, there exists a unique state trajectory for this beam model for every initial state and each twice continuously differentiable control input which is compatible with the initial state. In this paper, we study the motion planning problem of transferring the beam model from an initial state to a final state over a prescribed time-interval and then employ the results obtained to establish the approximate controllability of this model. We address these problems by extending and applying the generating functions approach to flatness-based control to the beam model. We prove that the transfer described above is feasible if the initial and final states belong to a certain set, which also contains the steady-states of the beam model. We then establish that this set contains all the eigenfunctions of the beam model, which form a Riesz basis for the state-space, and thereby conclude the approximate controllability of the beam model over all time intervals. We illustrate our theoretical results on motion planning using simulations and experiments.

Consider a non-uniform Euler-Bernoulli beam with a tip-mass at one end and a cantilever joint at the other end. The cantilever joint is not fixed and can itself be moved along an axis perpendicular to the beam. The position of the cantilever joint is the control input to the beam. The dynamics of the beam is governed by a coupled PDE-ODE model with boundary input. On a natural state-space, there exists a unique state trajectory for this beam model for every initial state and each smooth control input which is compatible with the initial state. In this paper, we study the motion planning problem of transferring the beam from an initial state to a final state over a prescribed time interval. We address this problem by extending the generating functions approach to flatness-based control, originally proposed in the literature for motion planning of parabolic PDEs, to the beam model. We prove that such a transfer is possible if the initial and final states belong to a certain set, which also contains steady-states of the beam. We illustrate our theoretical results using simulations and experiments.

Suppose that A and B are nonempty subsets of a complete metric space ( M , d ) and ϕ , ψ : A → B are mappings. The aim of this work is to investigate some conditions on ϕ and ψ such that the two functions, one that assigns to each x ∈ A exactly d ( x , ϕ x ) and the other that assigns to each x ∈ A exactly d ( x , ψ x ) , attain the global minimum value at the same point in A . We have introduced the notion of proximally F -weakly dominated pair of mappings and proved two theorems that guarantee the existence of such a point. Our work is an improvement of earlier work in this direction. We have also provided examples in which our results are applicable, but the earlier results are not applicable.

Porcine enterovirus G (PEV-G) presents a considerable threat to the swine industry, causing a range of diseases that include diarrhea, encephalomyelitis, reproductive disorders, and respiratory infections. Conventional diagnostic approaches, such as virus isolation and RT-PCR, are frequently labor-intensive and reliant on specialized equipments. Therefore, there is an immediate need for isothermal nucleic acid amplification techniques-specifically, Recombinase Polymerase Amplification (RPA) and Polymerase Spiral Reaction (PSR) that offer rapid, sensitive, and field-deployable detection of PEV-G. In this study, we successfully developed and optimized two isothermal nucleic acid amplification assays namely RPA/RT-RPA and PSR/RT-PSR to detect PEV-G in swine populations in Haryana. Primers were specifically designed to target the polyprotein region of PEV-G for both assays. Optimal conditions regarding temperature, incubation time, primer concentration, and magnesium ion concentration were established. The RPA assay demonstrated a sensitivity of 1.417 × 10⁴ copies with a detection time of just 20 minutes. The PSR assay exhibited a lower sensitivity of 2.3 x 10 5 copies in comparison to RPA assay in gel based detection system and required 2.5 hours for detection. Both assays showed exceptional specificity for PEV-G, with no observable cross-reactivity with other related porcine viruses. Additionally, visual detection using Picogreen dye provided a practical solution for field use, with limits of detection of 14 copies for RPA and 2.3 copies for PSR. Validation on 100 archived field samples showed that isothermal assays have comparable sensitivity to conventional PCR. This study underscores the potential of RPA and PSR as effective and cost-efficient diagnostic tools, enabling timely and precise detection of PEV-G in both laboratory and field contexts. Such advancements are vital for improving disease management strategies and reducing economic losses within the swine industry.

Pigs are a vital component of agricultural economies and a major source of livestock worldwide. The Porcine Stool-Associated virus (Posavirus), a newly identified member of the Picornavirales order, has been associated with enteric infections in swine. Recombinase Polymerase Amplification (RPA) and Polymerase Spiral Reaction (PSR), two isothermal amplification methods, were developed and optimized in this study to identify the posavirus in pig stool samples quickly and effectively. Primers that target the posavirus’s polyprotein region were designed for both RPA and PSR assays, and reaction parameters were optimized. Sensitivity assessments revealed that the RPA assay had a detection limit of 5.34 × 10 6 copies, while the PSR assay has higher sensitivity at 6.5 × 10 3 copies. Both assays showed high specificity for the posavirus, with no cross-reactivity. An evaluation of 132 field samples revealed that only three samples were positive for posavirus, highlighting the need for continued surveillance. This study reported the successfully development and optimisation of RPA and PSR assays as dependable and easily accessible diagnostic methods for posavirus detection. Their speed, sensitivity, and specificity make them adapted for use in a range of field and laboratory scenarios.