Scanning Capability Research Articles

An Efficient Conformal Stacked Antenna Array Design and 3D-Beamforming for UAV and Space Vehicle Communications.

In this paper, a new conformal array structure and beamforming technique are proposed to provide efficient communication performance for unmanned aerial vehicles (UAVs) and space vehicles. The proposed array is formed by conformally stacking cylindrical, conical, and concentric circular (CSC4) arrays which are all coaxially aligned with the same axis of the conformed body and with uniform interelement spacing. The array elements are then fed by a weighting vector that has an adaptive cosine tapered profile where the maximum amplitude coefficient is oriented with the mainlobe direction to improve the scanning capabilities of the array and increase the array effective area. In addition, for very large, conformed body structures such as space vehicles, a frontal mainlobe-oriented partial CSC4 array beamforming technique is proposed to efficiently utilize the large CSC4 structure, reduce the processing requirements for mainlobe electronic steering, and to provide very low sidelobe levels with reduced backlobe levels. Simulation results show that the proposed CSC4 design can provide wide scanning angles of up to angular range in the -direction with only change in the beamwidth, without increasing array size and with achievable sidelobe level of −45 dB and backlobe levels less than −10 dB.

Bridging the gaps for business growth among Indian construction companies

PurposeSuccessful handling and delivery of projects requires commensurate growth in the business capabilities of construction companies. The current scenario of exponential infrastructure boom in India necessitates scaling up to meet the challenges of competitiveness. The objectives of this study are to (1) identify the enablers of sustainable business growth among Indian construction companies, (2) identify gaps in the deployment of the enablers in comparison to competitive successful international construction companies and (3) suggest strategic initiatives to top management of companies and policymakers for promoting business growth and industry competitiveness.Design/methodology/approachA detailed literature review first identifies an adapted framework for enablers of growth and growth performance of successful international construction companies on basis of industry trends. Thereafter, a questionnaire survey was administered on the leading construction companies in India to assess the deployment of enablers and gaps thereof. A total of 108 valid responses were obtained from top management executives of the companies and analysed through descriptive statistics and hypothesis testing.FindingsStudies indicate that anticipation of new demands and capabilities; business opportunity scanning and human resource skills and capabilities are among the most important enablers of growth. The role of leadership vision and focus on development of human resources is critical to competitiveness and growth. The successful international construction companies have delivered growth utilising their ability to deploy multiple strategies, diversification and new business opportunities. These are sparingly deployed by Indian companies.Research limitations/implicationsThe study is limited to the opinion and perceptions of the top management personnel of the construction companies.Practical implicationsHigh economic growth context offers a unique opportunity for domestic Indian construction companies to leverage. The valuable insights gained from this study provide hints to the top management of these companies to draw managerial implications for facing the challenges ahead and delivering projects in the dynamic and hyper-competitive construction industry. The policymakers on their part are responsible to support and promote initiatives for sustainable growth.Originality/valueThe study suggests business growth enablers to construction companies in India to improve their international competitiveness.

A Dielectric Dome Antenna With Reduced Profile and Wide Scanning Capability

The design and experimental validation of a wide scanning dome antenna with reduced profile is presented. The antenna is based on the combination of a planar phased array with limited scanning capabilities and a dielectric lens which allows to broaden the field of view. The angular variation of the scan loss can be almost arbitrarily designed if no constraint is imposed on the size of the dielectric lens. However, the focus of this article is on the size minimization of the dome as required for applications where the form factor is critical. Therefore, a lower boundary of the height of the dome is derived and imposed as a design constraint. The antenna is analyzed using in-house ray tracing and physical optics software tools. It is shown that, when the array is combined with the dielectric dome, a significant directivity enhancement can be achieved for wide scanning. A demonstrator of the lens is designed, manufactured and combined with an available phased array working in Ku-band. The experimental tests confirm the theoretical predictions, validating the analysis tools, and show a scanning range of 70° in all scanning planes over a 15% bandwidth. The directivity is enhanced by approximately 2 dB at the limits of the scanning range compared to the standalone illuminating array. The active element pattern is rotationally symmetric, thus, the radiation performance is almost independent on the scanning plane. Moreover, the dielectric lens allows to preserve the cross-polarization performance of the illuminating array without adding a significant contribution.

Influence of injection technique, drug formulation and tumor microenvironment on intratumoral immunotherapy delivery and efficacy

BackgroundIntratumoral delivery of immunotherapeutics represents a compelling solution to directly address local barriers to tumor immunity. However, we have previously shown that off-target delivery is a substantial problem during intratumoral...

Terrestrial laser scanning intensity captures diurnal variation in leaf water potential

During the past decades, extreme events have become more prevalent and last longer, and as a result drought-induced plant mortality has increased globally. Timely information on plant water dynamics is essential for understanding and anticipating drought-induced plant mortality. Leaf water potential (ΨL), which is usually measured destructively, is the most common metric that has been used for decades for measuring water stress. Remote sensing methods have been developed to obtain information on water dynamics from trees and forested landscapes. However, the spatial and temporal resolutions of the existing methods have limited our understanding of the water dynamics and diurnal variation of ΨL within single trees. Thus, we investigated the capability of terrestrial laser scanning (TLS) intensity in observing diurnal variation in ΨL during a 50-h monitoring period. We aimed to improve the understanding on how large a part of the diurnal variation in ΨL can be captured using TLS intensity observations. We found that TLS intensity at the 905 nm wavelength measured from a static position was able to explain 77% of the variation in ΨL for three trees of two tree species with a root mean square error of 0.141 MPa. Based on our experiment with three trees, a time series of TLS intensity measurements can be used in detecting changes in ΨL, and thus it is worthwhile to expand the investigations to cover a wider range of tree species and forests and further increase our understanding of plant water dynamics at wider spatial and temporal scales.

Higher-Order Space Harmonics in Substrate Integrated Waveguide Leaky-Wave Antennas

The concept and feasibility of deploying higher-order space harmonics (HSHs) in 1-D periodic leaky-wave antennas (1-D periodic LWAs) is proposed, studied, analyzed, and demonstrated in this article. This can lead to the creation of multiband multibeam antennas (MBMBAs) with the capability of wide scanning ranges. To show the proposed concept, the excitation and flexibility of odd (n ε [-1, -3]) and even (n ε [-2, -4]) HSHs based on the analysis of a Brillouin diagram along with the effect of unit-cell geometrical structures of substrate integrated waveguide (SIW) for different propagating media are investigated. The proposed analysis is experimentally validated by prototyping and measuring a 1-D periodic LWA in SIW technology in which two HSHs (n ε [-1, -2]) are utilized for achieving a dual-band multibeam LWA with wide scanning range capability. In addition, a triple-band multibeam LWA design based on this concept is also analyzed and demonstrated where we take advantage of the characteristics of four HSHs (n ε [-1, -2, -3, -4]). Furthermore, the band edge issue of different stop-bands of HSH is also examined, and a method is proposed and used to address this issue where we use a quarter wavelength technique to overcome the matching problem at different frequencies related to different stop-bands of various HSHs (n ε [-1, -2, -3, -4]). Another design of a SIW-based 1-D periodic LWA is also discussed to extend and generalize the proposed concept in solving the mismatch issues of HSHs focusing on broadside radiation of the n $= -2$ space harmonic. The measured results are found to agree very well with their simulation and analysis counterparts.

A Multibeam Tapered Cylindrical Luneburg Lens

We present a cylindrical, multibeam, modified Luneburg lens antenna. The proposed antenna features low-profile, good impedance match, high gain, and wide angle scanning capability. We tapered the thickness of a dielectric disk along its radius to achieve the required refractive index profile of the lens in a nondispersive fashion. Seventeen dielectric-filled waveguide feeds, arranged circumferentially around the focal arc of the lens, provide almost invariant azimuthal scanning in the range of ±60° from broadside direction. The lens and the interior of the waveguide feeds are made of the same dielectric material, offering a smooth impedance transition from the feed antenna to the lens. A prototype of the antenna was fabricated and characterized. Measured reflection coefficient is better than -10 dB from 14 to 16 GHz. The isolations between feeds remain higher than 24 dB over the entire operational frequency range. We measured a maximum antenna gain of 20.5 dB with only 1.5 dB gain loss near the maximum 60° scanning angle. The proposed high-gain, multibeam antenna design can be used in a wide range of applications including automotive and surveillance radars.

Gain Enhancement of Transversely Slotted Substrate Integrated Waveguide Leaky-Wave Antennas Based on Higher Modes

A technique for gain enhancement of transversely slotted substrate integrated waveguide (SIW) leaky-wave antennas is proposed based on higher modes. Two SIW leaky-wave antennas based on the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m0</sub> ( m = 3, 5) higher modes are investigated. The antennas possess the advantage of simplicity, in which the feeding structures are compact and simple. Compared with published transversely slotted SIW leaky-wave antenna based on the fundamental mode (TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode), the proposed antennas exhibit higher and more consistent gains. Besides, the antennas maintain the scanning capability from near broadside to endfire. The working principles of the antennas are explained. The propagation characteristics are investigated with a magnetic field integral method. The aperture efficiencies are analyzed. Two leaky-wave antenna designs based on the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">50</sub> higher modes are demonstrated and compared with a TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> -mode antenna design (with almost the same dispersion characteristics). Prototypes of the three designs are fabricated and measured for comparisons. Compared with the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> -mode antenna, the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30</sub> - and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">50</sub> -mode antennas have the transverse beamwidths markedly narrowed and have the gains improved by about 5.5 and 8 dB, respectively.

Ultralightweight resilient mutual authentication protocol for IoT based edge networks

Confidentiality and authentication are primary concerns of RFID (Radio Frequency IDentification) based identification systems. Low cost, non sight-line scanning capability, unique identification and functional haste make RFID systems much more suitable for supply chain management and IoT networks, compare to barcodes and magnetic tapes. Since, RFID tags can be scanned from a greater distance over a radio channel which is easily accessible for adversaries, therefore numerous Ultralightweight Mutual Authentication Protocols (UMAPs) have been proposed to ensure the security of the RFID systems in a cost effective way. These UMAPs mainly involve low cost bitwise logical ( $$Triangular$$ ) operations such as $$XOR, AND OR$$ etc., usually these logical operations offer poor diffusion properties and hence result in disclosure of the concealed secrets. Almost all of the previous UMAPs have certain pitfalls and reported to be susceptible to Denial of Service, traceability, full disclosure and cloning attacks. In this paper, we propose a new UMAP that is resilient to structured and unstructured cryptanalysis techniques. The proposed Ultralightweight Resilient Mutual Authentication Protocol (URMAP) avoids all the pitfalls and unbalanced operators in its design that were the main reasons of failure of previous UMAPs. The incorporation of ultralightweight primitives; $$Per{\text{-}}XOR$$ ( $${P}_{x})$$ and $$Inverse Per{\text{-}}XOR$$ $$({ P}_{x}^{-1})$$ makes the protocol messages more resistant to all types of adversaries. The security and privacy capabilities of URMAP are evaluated through formal analysis. The results of GNY Logic analysis prove that the proposed protocol is resilient to all possible attack scenarios thus ensuring optimal confidentiality, integrity and availability services.

A High-Gain Leaky-Wave Antenna Using Resonant Cavity Structure With Unidirectional Frequency Scanning Capability for 5G Applications

This paper presents a high-gain leaky-wave antenna based on a resonant cavity (RC) structure with the capability of unidirectional beam scanning over predefined frequencies and desired beam angles. Frequency scanning is achieved by implementing a properly-designed single-layer partially reflective surface (PRS) based on a simple ray tracing-based design procedure. In the proposed structure, two techniques are combined to make the beam scanning unidirectional. First, a metallic wall is placed at a proper distance from the radiator to suppress the antenna propagation at undesired directions. Second, a feed antenna with a tilted beam is designed as the main radiating element inside the cavity to radiate over desired beam angles. A prototype of the proposed antenna is fabricated and measured demonstrating a beam scanning from $12^{o}$ to $46^{o}$ over the frequency band from 25 to 31 GHz. Moreover, a maximum gain of 15.4 dBi is achieved at 26 GHz on the elevation plane with tilted angle of $22^{o}$ . The proposed leaky-wave antenna is suitable for various wireless applications, in particular the $5^{th}$ generation of cellular networks and small cell base station antenna (BSA) applications.

Wide-angle scanning linear phased arrays based on wide-beam magneto electric dipole antenna

Microstrip phased array has aroused interest of many researchers because of its beam agility. However, a big problem for typical microstrip array is that its main beam can only scan from about –50° to 50°, with a gain loss of 4-5 dB. Meanwhile, the relatively narrow operating bandwidth of microstrip antenna is also a problem in application. These flaws have dramatically limited its applications and spawned many studies on phased array with wide-angle scanning capability. Several methods have been proposed to broaden the scanning coverage of phased array, such as utilizing pattern-reconfigurable antenna as an element of array, taking wide-beam antenna as the element of array, and adopt metasurface as the top cladding of array. However, most of existing researches mainly focus on achieving wide-angle scanning performance within a relatively narrow bandwidth. A phased array that possesses wide-angle scanning capability at both main planes within a relatively wide bandwidth is highly desirable. In this paper, a wide-beam magnetoelectric (ME) dipole antenna is proposed. It consists of an ME dipole antenna in the form of microstrip patch and a pair of magnetic dipoles. Metallic through holes integrated with patches and ground are utilized to form magnetic currents. Extra magnetic dipoles are added to broaden the 3-dB beam-width. The simulated results reveal that the 3-dB beam-width of the proposed antenna is greater than 107° in the E-plane (9 GHz–12 GHz) and 178° in the H-plane (7 GHz–12 GHz) respectively. The impedance bandwidth of the proposed antenna is 53.26% from 7.3 GHz to 12.6 GHz (VWSR &lt; 2). Based on the proposed antenna element, two linear phased arrays are fabricated and measured. To test the wide-angle scanning capability of the arrays, each antenna element is simply fed with alternating currents with identical amplitude and linearly increasing phases. The measured results reveal that the wide-angle scanning capability of H-plane array and E-plane array can be obtained from 9 GHz to 12 GHz. The scanning beam of the H-plane array can cover the range from -90° to 90°. The scanning beam of the E-plane array can cover the range from –70° to 70°. The impedance bandwidth of the central antenna is 27.03% for the H-plane array from 9.6 GHz to 12.6 GHz (active VWSR &lt; 2.5) and 36.36% for the E-plane array from 9 GHz to 13 GHz (active VWSR &lt; 2) respectively. Hence, the proposed method can be used as a reference for designing a wide-beam antenna and wide-angle scanning phased array and the designed phased arrays can be applied to X-band radar systems.

A Compact Dual-Band and Dual-Polarized Millimeter-Wave Beam Scanning Antenna Array for 5G Mobile Terminals

This paper presents a compact dual-band and dual-polarized millimeter-wave patch antenna array with satisfactory performance on element mutual coupling and beam scanning capabilities. Using capacitive feed technique and stacked configuration with extra parasitic strips, the proposed antenna array is able to achieve a wide operating bandwidth in both the low- and high-bands. In order to reduce the array's footprint, and to enhance the beam scanning performance in both bands, the element spacing is shrunk to less than 0.36 wavelength at 26 GHz. To improve the isolation between array elements due to their small spacings, two effective decoupling approaches are adopted, which result in a 6-dB isolation enhancement. The overall size of the proposed antenna array is only 18.2 mm ×4.1 mm ×1.07 mm, which is smaller than some industrial mm-Wave antenna modules released recently. Our simulation shows that the antenna array can fully cover the 5G NR bands of n258~n261 simultaneously. The four-element array provides ±60° and ±45° beam scanning performance in the low- and high-bands, respectively. The experimental data of reflection coefficient, mutual coupling, and radiation patterns confirm with the simulated results, rendering the proposed array to be a good candidate for 5G mm-Wave communications.

Focus on photonics, spectroscopy, and spectrometry

Focus on photonics, spectroscopy, and spectrometry

Single-cell omics analyses with single molecular detection: challenges and perspectives

The ultimate goal of single-cell analyses is to obtain the biomolecular content for each cell in unicellular and multicellular organisms at different points of their life cycle under variable environmental conditions. These require an assessment of: a) the total number of cells, b) the total number of cell types, and c) the complete and quantitative single molecular detection and identification for all classes of biopolymers, and organic and inorganic compounds, in each individual cell. For proteins, glycans, lipids, and metabolites, whose sequences cannot be amplified by copying as in the case of nucleic acids, the detection limit by mass spectrometry is about 105 molecules. Therefore, proteomic, glycomic, lipidomic, and metabolomic analyses do not yet permit the assembly of the complete single-cell omes. The construction of novel nanoelectrophoretic arrays and nano in microarrays on a single 1-cm-diameter chip has shown proof of concept for a high throughput platform for parallel processing of thousands of individual cells. Combined with dynamic secondary ion mass spectrometry, with 3D scanning capability and lateral resolution of 50 nm, the sensitivity of single molecular quantification and identification for all classes of biomolecules could be reached. Further development and routine application of such technological and instrumentation solution would allow assembly of complete omes with a quantitative assessment of structural and functional cellular diversity at the molecular level.

Wide-Band and Wide-Angle Scanning Phased Array Antenna for Mobile Communication System

A wide-band phased array antenna with wide-angle scanning capability for mobile communication system is proposed in this article. An air cavity is properly embedded into the substrate under each array element. This method is very simple and can efficiently enhance wide-angle scanning performance by improving the wide-angle scanning impedance matching (WAIM) and realizing the beam-width of elements in the array. Besides, the operating bandwidth is also extended with the proposed approach. The wide-angle scanning capability is analyzed and verified by both the linear array antennas (on large ground planes in detail) and the planar array. Two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 8$ </tex-math></inline-formula> linear arrays and one <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> planar array are demonstrated, which achieve the beam scanning of around ±60° with a realized gain reduction under 3.5 dB in the wide operating bandwidth (37.4%). Furthermore, the beam in the E-plane can scan over ±70° with a realized gain reduction under less than 3 dB. Two linear array prototypes with wide-angle scanning capacity in two planes are fabricated and characterized, yielding good performance within overall operational bandwidth. The measured results align very well with the simulated. The proposed wideband phased array with large scanning coverage is a promising candidate for 5G mobile communications.

Integration of nuchal translucency screening into the first-trimester fetal anatomy scan: the time has come.

Integration of nuchal translucency screening into the first-trimester fetal anatomy scan: the time has come.

The Influence of Image Processing and Layer-to-Background Contrast on the Reliability of Flatbed Scanner-Based Characterisation of Additively Manufactured Layer Contours

Flatbed scanners (FBSs) provide non-contact scanning capabilities that could be used for the on-machine verification of layer contours in additive manufacturing (AM) processes. Layer-wise contour deviation assessment could be critical for dimensional and geometrical quality improvement of AM parts, because it would allow for close-loop error compensation strategies. Nevertheless, contour characterisation feasibility faces many challenges, such as image distortion compensation or edge detection quality. The present work evaluates the influence of image processing and layer-to-background contrast characteristics upon contour reconstruction quality, under a metrological perspective. Considered factors include noise filtering, edge detection algorithms, and threshold levels, whereas the distance between the target layer and the background is used to generate different contrast scenarios. Completeness of contour reconstruction is evaluated by means of a coverage factor, whereas its accuracy is determined by comparison with a reference contour digitised in a coordinate measuring machine. Results show that a reliable contour characterisation can be achieved by means of a precise adjustment of image processing parameters under low layer-to-background contrast variability. Conversely, under anisotropic contrast conditions, the quality of contour reconstruction severely drops, and the compromise between coverage and accuracy becomes unbalanced. These findings indicate that FBS-based characterisation of AM layers will demand developing strategies that minimise the influence of anisotropy in layer-to-background contrast.

High-resolution beam scanning technique with microlens array and adaptive fiber-optics collimator.

Conventional beam scanning systems employing a microlens array (MLA) suffer from the problem that only discrete diffraction angles can be addressed because of the periodic structure of the MLA. In this paper, an adaptive fiber-optics collimator (AFOC) that continuously adjusts the position of light source (optic fiber output) is used in front of the periodic structure as a moving linear phase shifter to overcome this discrete scanning angle problem. By introducing the AFOC into the beam scanning system employing MLA, a beam scanning system with continuous scanning capability and high resolution is fulfilled. Theoretical simulations and experimental results both demonstrate the continuous high-resolution scanning capacity of the beam scanning system employing both MLA and AFOC. The proposed beam scanning system is expected to find wide applications in space optical communication, optical interconnection, power projection, and coherent beam combining.

Ultrafast Surface Plasmon Resonance Imaging Sensor via the High-Precision Four-Parameter-Based Spectral Curve Readjusting Method.

A variety of surface plasmon resonance (SPR) sensing devices have been extensively used in biochemical detection for their characteristics of label-free, highly sensitive, and faster detecting. Among them, the spectrum-based SPR sensing devices have offered us great advantages in high-throughput sensing due to their large dynamic range and the possibility of detection resolution similar to that offered by angle interrogation. This paper demonstrates a spectrum-based SPR imaging sensing system with fast wavelength scanning capability achieved by an acousto-optic tunable filter (AOTF) and a low-cost and speckle-free halogen lamp implemented as the SPR excitation source. Especially, we developed a novel four-parameter-based spectral curve readjusting (4-PSCR) method for data processing, which offered us a faster and more accurate spectral data curve fitting process than the traditional polynomial fitting method. With the configuration, we have also conducted an SPR high-throughput detection of the novel coronavirus (COVID-19) spike protein, proving its application possibility in the screening of COVID-19 with high accuracy. We believe that the higher sensitivity and accuracy of the system have made it readily used in biochemical imaging and detecting applications.

Multiprobe scanning probe microscope using a probe-array head

We have developed a microelectromechanical system (MEMS)-based multiprobe scanning probe microscope (SPM) to improve imaging efficiency. The SPM head contains seven identical MEMS probes, and each of them integrates a displacement sensor and a Z-axis actuator. Force constant mode is designed based on the force feedback strategy rather than on the position feedback strategy for this kind of SPM head. A nano-measuring machine is equipped with the lateral XY scanners, which can reach a motion range of 25 mm × 25 mm. After calibration, the measurement of one-dimensional grating has been made to demonstrate the capability of multiprobe scanning.