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This research explores the dynamic responses of reinforced concrete (RC) slabs under high-velocity impacts. The study utilizes advanced numerical simulations to investigate the effects of varied impact loading and slab depths, unveiling complex rate-dependent behaviors (i.e., impact forces, reactions, accelerations, and displacements) across a diverse range of velocities. The alignment of simulation results with experimental data validates the robustness and accuracy of the employed approach. Additionally, an analytical model predicting the load-carrying capacity and deflection of these slabs under high-velocity loads is proposed. The results indicated that higher loading rates correlate with increased forces and damage until perforation. Analytical models exhibit strong performance within a ±10% error margin, and response surface analysis quantifies the impactor velocity's influence on load for a constant thickness. Overall, this investigation sheds light on the dynamic complexities of RC slabs subjected to high-velocity impacts, providing valuable insights for structural design considerations. [ABSTRACT FROM AUTHOR]

Ferrocement is extensively utilized in construction as a structural material, given its exceptional mechanical properties and impact strength. This study aimed to analyze the performance of ferrocement that is reinforced with recycled steel wire tires under static loads. This current study a comparative investigation of behavior of compressive strength of ferrocement cubes and flexural behavior of ferrocement panels and behavior of ferrocement panels reinforced with tire Steel wire tires under static loads. Ferrocement slabs sample was (L 500 x W 500 x t 50mm) in size, and 15 slabs were subjected to static point load. The number of wire mesh layers, which was replaced by recycling tire steel wire as a ratio of the volume of wire mesh, was the main parameter in the current study. The percentage of recycle steel wire tires are 33% and 66% and 99% from of steel wire mesh for reinforcements of ferrocement panels. The results presented, the behavior of panels under static load at ultimate failure and first crack. It showed that ferrocement have 99.0% steel wire tires gave a good performance under static loading which were required to increase the load value to make the first crack and ultimate failure, and causing late of the failure and less deflection. [ABSTRACT FROM AUTHOR]

Bamboo is a naturally sustainable material that has been used in construction for a very long time. Investigations on the feasibility of using bamboo for reinforcing concrete have been carried out by various researchers. However, the lack of construction codes and design procedures for bamboo-reinforced concrete (BRC) structures is preventing structural engineers and construction firms from using bamboo in construction. The aim of this work was therefore to review various BRC structural elements, including beams, columns, slabs and walls, in order to develop guidelines for using them confidently. [ABSTRACT FROM AUTHOR]

This study presents the results of an investigation of the effect of biaxial geogrid reinforcement on the load-carrying capacity of rigid pavement slabs. Six concrete slabs having dimensions of 800 × 800 × 50 mm were prepared and tested under static loads at three different locations: interior, edge and corner of the slab. Three of the slabs were unreinforced and taken as references. The other three slabs were reinforced with a biaxial geogrid layer. Study parameters investigated in this study included the load-carrying capacity, ductility and failure modes of the slabs. The experimental results were verified theoretically using the finite-element software ABAQUS. The findings indicated that the load-carrying capacity and ductility of the concrete slabs reinforced with the biaxial geogrid can be improved. Test results obtained indicated that the maximum load-carrying capacity of the concrete slabs reinforced with the biaxial geogrid was increased by 25%, 26% and 29% for interior, edge and corner loading locations, respectively. [ABSTRACT FROM AUTHOR]

Classical models for the passive myocardium, such as the Fung and Holzapfel-Ogden models, are known to have high degeneracy as well as numerous mechanical and mathematical limitations, preventing their utility in microstructural experiments and precision medicine. Hence, the upper triangular (QR) decomposition and orthogonal strain attributes were leveraged to develop a new model using published biaxial data on slabs of left myocardium, resulting in a separable strain energy function. This new model, the Criscione-Hussein model, was compared with both the Fung and Holzapfel-Ogden models by quantifying the uncertainty, computational efficiency, and material parameter fidelity for all three models. As a result, the Criscione-Hussein model was found to significantly reduce the uncertainty and computational time (p < 0.05) and enhance the fidelity of the material parameters. Hence, the Criscione-Hussein model enhances the predictability for the passive behavior of the myocardium and may serve a role in creating more accurate computational models that provide better visualizations for the mechanical behavior of the heart and enable the experimental connection between the model and the myocardial microstructure. [ABSTRACT FROM AUTHOR]

This paper aims to explore the structural performance of 3D-printed and casted cement-based steel-reinforced concrete beams and one-way slabs incorporating short carbon fibre and activated carbon powder, which have been shown to enhance concrete's flexural strength and reduce its electrical resistivity. The samples are cast and printed in 250 × 325 × 3500 mm beams and 150 × 400 × 3500 mm one-way slabs and mechanical, electrical, and piezoresistivity properties were measured. This length of beams and one-way slabs with rebars have been considered as they can magnify the flexural and cracking behaviour and make them easier to be monitored and analysed. The samples were loaded up to 80% of maximum stress. Crack propagation and strain was assessed using the 2D digital image correlation (DIC) method. The results compared samples under continuously increasing loads between 3D-printed and cast samples. The 3D-printed composites had a better piezoresistive response due to the enhanced anisotropic behaviour. DIC analysis illustrated similar results among different samples, while 3D-printed blocks had lower cracking performance due to the horizontal case fracture in lower stress. [ABSTRACT FROM AUTHOR]

In the state of Paraná, strawberry farming is relevant, however, it is still an expanding market. Understanding and determining the main economic aspects related to cultivation becomes essential for the success of the enterprise. The objective of this study was to survey the main costs of establishment, management, and economic viability of organic strawberry farming in a soilless substrate system in Laranjeiras do Sul-PR. The study was conducted in the 2022 crop season and divided into three stages. The first stage involved a literature review of all aspects of organic strawberry farming in a soilless substrate system. The second stage consisted of a case study, and the third stage involved the analysis of production costs and economic viability of the crop. The total costs of managing and establishing a 250 m² greenhouse with 1800 strawberry plants reached R$ 39,147.00, with the most significant cost components being related to the structure, especially eucalyptus poles. The following financial viability indices were used: Net Present Value (NPV), Internal Rate of Return (IRR), and Discounted Payback Period. The results obtained indicate financial viability in production, as the NPV was R$ 69,509.88; the IRR was 57%; the profitability was R$ 25.097,00 per year in a 250 m² greenhouse, and the Payback Period was 1.6 years. Analyzing these indices confirms that the investment is viable and promising. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of fiber on the behavior of punching shear slabs; a finite element modeling approach is used to simulate the case study. The proportion mix of hybrid fiber-reinforced concrete, which contains 0.2 percent macro synthetic fibers and 0.68, 0.8, and 0.96 percent steel fibers, compressive strengths of 50 MPa, different longitudinal reinforcement used, and slab thicknesses of 150, 200, and 250 mm are all joined and investigated in this study. The ATENA software is used to perform nonlinear finite element analysis. The slab results validation was done similarly to previous experimental work, and the acquired results indicated a significant agreement. Thirty-six two-way specimen slabs with dimensions of 1900 × 1900mm were modeled in this investigation. All four sides of the slabs are supported. The results showed that the slabs' ultimate shear capacity increases with increasing the hybrid steel fiber. Nevertheless, the ultimate capacity of the slabs has decreased due to an increase in the reinforcement ratio and slab thickness. [ABSTRACT FROM AUTHOR]

Several existing reinforced concrete structures (RC) require improvement in performance for reasons of deterioration. This is due to many factors such as the change in code requirements. The current study was assisted by experimental models to investigate the behavior of RC slabs strengthened with carbon fiber reinforced polymer (CFRP) laminates and sheets. Seven RC slabs strengthened with CFRP (laminates and sheets) were tested. The slabs were divided into four groups. The first phase includes one slab without strengthening (reference slab), the second phase includes one slab strengthened with CFRP laminates, and the third phase includes one slab strengthened with CFRP sheets. The fourth phase includes four slabs strengthened with different areas of sheets. The major test parameters included the different types of strengthening materials and the corresponding types of epoxies used for each type of CFRP. A comparison between the two types of CFRP was conducted. The load deflection, load strain and mode of failure were investigated. Test results demonstrated that the flexural strength increased, and the ductility reduced with the increase in the area of CFRP sheets. for almost equivalent applied area, CFRP Sheets has more significant influence on the behavior of the strengthened slabs than laminates. Strengthening of RC slabs with CFRP improves the flexural strength capacity for both types. For the same CFRP strength, the sheets showed a cost reduction of 70%. The difference is attributed to the difference in the mechanical properties and the bonding quality of the CFRP material. [ABSTRACT FROM AUTHOR]

A mechanical model has been developed by the authors in order to predict the shear strength of reinforced concrete slabs under concentrated loads close to linear supports. The model takes into account a significant number of variables involved in the phenomenon, such as the clear shear span, the concrete compressive strength, the reinforcement ratio, the effective depth, the load spreading angle, the size effect and the size of the loaded area. It is applicable to simply supported slabs, cantilever slabs and situations with partial restraint to the rotation, such as intermediate supports. It has been validated with a database of 90 shear test in slabs subjected to a single concentrated load in different supporting conditions, yielding results on the safe side and showing low scatter. A parametric analysis of the model is also presented, detailing how the different involved variables affect the shear strength. These results, along with the simplified expressions for the shear strength calculation, provide a useful tool for the assessment of the shear strength of reinforced concrete solid slabs in daily engineering. [ABSTRACT FROM AUTHOR]

Flexural shear behavior, which mainly concerns reinforced concrete (RC) slabs without shear reinforcement, is usually investigated by means of simply supported, beam‐shaped specimens. Only few tests are available where the cross‐section properties correspond to a slab (b ≫ h) or the support conditions lead to moment and shear force distributions of multi‐span slab systems. The moment distribution in the vicinity of inner supports can decrease shear slenderness and, hence, increase shear strength. An increase in member width is also often associated with a beneficial effect on load bearing behavior. Firstly, the course of the shear crack changes along the width which, both, increases the crack face area, and potentially allows for an increased interlocking effect of the two crack faces. Secondly, a (wide) slab's ability to redistribute inner stresses in lateral direction can compensate inner irregularities. However, the likelihood of irregularities to occur after all, increases with increasing concrete volume, so larger member widths. A comparison of existing investigations shows that the findings are partly inconclusive. Also, no studies addressing the influence of the member width exist with tests in the vicinity of intermediate supports despite being the typical shear‐critical section in actual members. To address related open questions, an experimental campaign comprising 20 shear tests on slab segments without shear reinforcement was conducted. Essentially, member width (b = 0.3 or 2.4 m) and support conditions were varied within the test program. Main goal of the experimental campaign was finding answers to the question whether one‐way flexural shear strength is influenced by the member's width. This has been addressed by generating results from pairs of tests which differed only in their width while having otherwise equal properties (b/h ≈ 1.0 and b/h ≈ 8.5). Eight such pairs were tested featuring different shear span lengths, rotational restrains at the support and longitudinal reinforcement ratios. In contrast to other experimental campaigns, shear tests near inner supports were incorporated in the experimental program. On average, the gain in shear capacity of the wide members compared to the reference linear member was proportional to the increase in width. It can thus be concluded that linear (beam‐shaped) specimens are suitable for representing one‐way shear capacity of RC slabs. Enhanced shear response of actual slabs can rather be ascribed to beneficial effects from loading and support conditions which enable to partially activate two‐way stress distribution or compressive membrane action. Additionally, rare occurrence of damages in RC slabs is not only to be attributed to an underestimation of capacity but probably also to an overestimation of design load. [ABSTRACT FROM AUTHOR]

Background: Current clinical positron emission tomography (PET) systems utilize detectors where the scintillator typically contains single elements of 3–6‐mm width and about 20‐mm height. While providing good time‐of‐flight performance, this design limits the spatial resolution and causes radial astigmatism as the depth‐of‐interaction (DOI) remains unknown. Purpose: We propose an alternative, aiming to combine the advantages of current detectors with the DOI capabilities shown for monolithic concepts, based on semi‐monolithic scintillators (slabs). Here, the optical photons spread along one dimension enabling DOI‐encoding with a still small readout area beneficial for timing performance. Methods: An array of eight monolithic LYSO slabs of dimensions 3.9 × 32 × 19 mm3 was read out by a 64‐channel photosensor containing digital SiPMs (DPC3200‐22‐44, Philips Digital Photon Counting). The position estimation in the detector's monolithic and DOI direction was based on a calibration with a fan beam collimator and the machine learning technique gradient tree boosting (GTB). Results: We achieved a positioning performance in terms of mean absolute error (MAE) of 1.44 mm for the monolithic direction and 2.12 mm for DOI considering a wide energy window of 300–700 keV. The energy resolution was determined to be 11.3%, applying a positional‐dependent energy calibration. We established both an analytical and machine‐learning‐based timing calibration approach and applied them for a first‐photon trigger. The analytical timing calibration corrects for electronic and optical time skews leading to 240 ps coincidence resolving time (CRT) for a pair of slab‐detectors. The CRT was significantly improved by utilizing GTB to predict the time difference based on specific training data and applied on top of the analytical calibration. We achieved 209 ps for the wide energy window and 198 ps for a narrow selection around the photopeak (411–561 keV). To maintain the detector's sensitivity, no filters were applied to the data during processing. Conclusion: Overall, the semi‐monolithic detector provides attractive performance characteristics. Especially, a good CRT can be achieved while introducing DOI capabilities to the detector, making the concept suitable for clinical PET scanners. [ABSTRACT FROM AUTHOR]

An extraction technique is proposed for electromagnetic characterization of metal-backed multilayer metamaterial (MM) structures demonstrating reflection-asymmetric property. It uses recursive scattering parameters for direct and reversed configurations of a multilayer structure. The algorithm was validated by comparing the extracted electromagnetic properties of multilayer structures composed of different MM unit cells with those determined by one-layer-only S-parameter methods. Two-layer and three-layer multilayer structures composed of MM slabs with C-shaped and $\Omega $ -shaped rings and an FR4 material were fabricated and measured for experimental validation. A sensitivity analysis was also conducted to quantitatively evaluate the performance of our method against a small air gap between the multilayer structures and the short-circuit termination and between adjacent MM slabs within these structures. Strong agreement was observed between the resulted obtained using our method and measurements. [ABSTRACT FROM AUTHOR]

This article presents a 3-D printed dielectric polarizer. It is constituted by a number of annually arranged dielectric slabs, and each slab is 45° rotated with respect to the azimuth plane. It is able to transform the polarization state of the waves in azimuth plane from linear to circular. Based on the polarizer, two circularly polarized (CP) antenna designs are proposed. One of them is an omnidirectional CP antenna, and the other is a multibeam CP antenna with capability of full azimuthal scanning. They are fed by a dielectric filled biconical structure and six corner reflectors, respectively. Their polarizers are individually designed with different geometric parameters. Both antennas are one-piece configurations and can be directly 3-D printed without assemblies in later stage. Partial surfaces of the antennas are coated with copper films by an electroplating technique to act as the necessary metal components. To validate the design ideas, two prototypes are demonstrated in X-band. Experimental results show that the omnidirectional antenna can achieve a wide 3 dB axial ratio (AR) bandwidth of 28.3% from 8.5 to 11.3 GHz and a peak gain of 3.3 dBic. Meanwhile, the multibeam antenna is with a wide 3 dB AR bandwidth of 22.4% from 8.7 to 10.9 GHz and a peak gain of 9.2 dBic. Within the AR bandwidth, the AR values in full azimuth plane are lower than 3 dB. [ABSTRACT FROM AUTHOR]

This work presents an ultrawideband and high-absorption structure (UHAS) obtained by a fast design method. The proposed analytic approach can simply design single-FSS-layer absorber with ideal performance stability under oblique incidence. With this method, a composite material reinforced circuit-analog (CA) absorber is designed, which unit cell of CA sheet is a square ring loaded with chip resistors. At normal incidence, both TE and TM polarization simulation results demonstrate that the reflection coefficient below −10 dB is from 5.8 to 22.2 GHz; meanwhile, the reflection coefficient less than −20 dB covers a bandwidth of 7.4–19.1 GHz; also, there is a −30 dB absorption band in 8.6–17.2 GHz. Furthermore, under TE polarization, experimental results indicate that UHAS can maintain a −20 dB absorption band from 7.4 to 18.0 GHz within 40° oblique angle of incidence; −10 dB absorption is from 6.1 to 18.0 GHz within 50° oblique angle of incidence. The good agreement between simulation and measurement validates the proposed method and UHAS. Finally, the UHAS, with a protective layer, will be more stable in practical applications. [ABSTRACT FROM AUTHOR]

The dynamics of the Alps and surrounding regions is still not completely understood, partly because of a non‐unique interpretation of its upper‐mantle architecture. In particular, it is unclear if interpreted slabs are consistent with the observed surface deformation and topography. We derive three end‐member scenarios of lithospheric thickness and slab geometries by clustering available shear‐wave tomography models into a statistical ensemble. We use these scenarios as input for geodynamic simulations and compare modeled topography, surface velocities and mantle flow to observations. We found that a slab detached beneath the Alps, but attached beneath the Northern Apennines captures first‐order patterns in topography and vertical surface velocities and can provide a causative explanation for the observed seismicity. Plain Language Summary: Present‐day surface deformation, including earthquakes, plate motion, and mass (re)distribution, results from processes operating at the surface and in the interior of the Earth. Understanding these processes and their coupling is of utmost importance in light of the hazard they pose to society. The Alps provide an excellent natural laboratory to understand such coupling. Here, we use seismic tomography models to constrain its upper‐mantle architecture. We further use these models to quantify forces originating from the resolved architecture and their effects on the present‐day surface deformation. The models can reproduce first‐order patterns in the observed topography and vertical surface motions. We found a causative correlation between the presence of a shallow slab attached to the overlying lithosphere in the Northern Apennines and the seismicity in the region. Our results allow us to better understand the transfer of internal forces to the surface, thereby helping to quantify the present‐day mechanical setup of the area. Key Points: Statistical ensemble of S‐wave tomography models is used to infer the Lithosphere‐Asthenosphere Boundary configuration and slab geometries in the AlpsThe 3‐D upper‐mantle architecture from the statistics reproduce first‐order patterns in observed topography and Global Navigation Satellite Systems vertical velocitiesA shallow/attached slab in the Northern Apennines is consistent with the mantle depth seismicity observed in this region [ABSTRACT FROM AUTHOR]

A novel electromagnetic transparent low-band (LB) antenna is given in this article, with a good impedance matching in the band of 0.69–0.96 GHz (VSWR < 1.5). The key feature lies in its great patch dipoles with low-scattering properties. The transparent performance is achieved by loading slots on the dipoles, instead of inserting chokes. Dagger-like slot plays an important role in both impedance matching improvement and scattering suppression. An extra resonance point can be introduced to the reflection coefficient curve in the operating band, so the impedance matching problems can be alleviated. Besides, a dual-band shared-aperture array was designed and fabricated for validation. Both simulated and measured results have proved that the LB antenna has satisfactory impedance characteristics within the operating band and achieves an electromagnetic transparency in the band of 1.7–2.4 GHz. [ABSTRACT FROM AUTHOR]

In this article, we demonstrate how a generative neural network enables the inverse design of a real-time beamforming structure that consists of simply eight rotatable dielectric slabs but involves high nonlinearity. The determination of the optimal architecture and the detailed training process is discussed, and the advantage of the proposed method over some conventional numerical methods is shown. The system is realized and measured with a platform controlled by a low-cost system-on-a-chip (SoC) computer to verify its real-time design capability. We showcase the proposed neural network as a competitive candidate for complex real-time reconfigurable EM designs. [ABSTRACT FROM AUTHOR]

This paper focuses on the investigation of the flexural behaviour of steel-concrete composite beams through non-linear finite element analysis. Both geometries, as well as material non-linearity, are considered. Steel-concrete composite beams are typically made consisting of a hot-rolled I-section steel beam and a concrete slab that is connected monolithically by using a shear connector. A shear connector is one of the key elements for developing the composite action used in steel-concrete composite structures. This paper deals with the flexible shear connectors such as studs and channels designed as per the Indian standards 11384. Initially, the FE models are validated by making comparisons with the experimental test results obtained by previous researchers, as available in the literature. In the present study, thirty three-dimensional simply supported composite beams are created and analysed using finite element commercial software package ANSYS15 workbench version subjected to two-point loads. The degree of shear connection, the strength of steel section and the geometry of stud and channel connectors are the primary parameters considered for the present research work, and the results are compared. The overall flexural response is provided, including failure modes, load-central deformation behaviour, and interface slip, as well as the effects of yield strength of steel, the geometry of the stud and channel shear connector along with the degree of shear interaction, are evaluated. The results show that the degree of interaction, the geometry of shear connectors and steel yield strength have significant influence. Subjected to flexure, steel-concrete composite beam section with channel connector is less evaluated so far; therefore, in the present research work, channel shear connector is taken into account to evaluate the flexural behaviour with the consideration of varying grades of steel section along with the degree of interaction and to compare the results with a different section of shear connectors. [ABSTRACT FROM AUTHOR]

In this article we present the design of a 120 GHz 2 $\times $ 2 dipole array in a 130 nm SiGe technology, which employs dual mode substrate wave cancellation to improve radiation efficiency and to avoid uncontrolled radiation from the chip edges. We show a systematic analysis of the involved dielectric slab modes TM0 and TE1 and their effects on the radiation pattern and efficiency. Based on this, the position and orientation of the array elements are derived for optimal cancellation of substrate waves and different feeding techniques are compared. The dipole array shows a measured realized gain of 1 dBi [including ground signal ground (GSG)-pad, Balun, and matching-capacitor, all on-chip], an $S_{11}$ -bandwidth of 18 GHz, and a realized gain bandwidth of 16 GHz. Very good correlation between simulations and measurements is achieved through careful modeling of the probe effects. The presented results provide useful insight on the design of on-chip dipole arrays for future millimeter-wave applications in standard SiGe or CMOS technologies. [ABSTRACT FROM AUTHOR]

Modeling the electromagnetic response of carbon nanotube (CNT) reinforced composites is inherently a 3-D multiscale problem that is challenging to solve in real time for nondestructive evaluation (NDE) applications. This article presents a fast and accurate full-wave electromagnetic solver based on a multilayer dyadic Green’s function approach. In this approach, we account for the effects of the dielectric slab, where the CNTs are embedded, without explicitly discretizing its interfaces. Due to their large aspect ratios, the CNTs are modeled as arbitrary thin wires (ATWs), and the method-of-moment (MoM) formulation with distributed line impedance is used to solve for their coupled currents. The accuracy of the in-house solver is validated against the commercial MoM and the finite element method (FEM) solvers over a broad range of frequencies (from 1 GHz to 10 THz) and for a wide range of dielectric slab properties. Examples of 100 nm-long vertical and horizontal CNTs embedded in a 1 $\mu \text{m}$ -thick lossy dielectric substrate are presented. The in-house solver provides more than $50\times $ speed up while solving the vertical CNT and more than $570\times $ speed up while solving the horizontal CNT than a commercial MoM solver over the GHz-to-THz frequency range. [ABSTRACT FROM AUTHOR]

A new 3-D-printed wideband circularly polarized (CP) dielectric resonator antenna (DRA) with two printing materials is investigated. The DRA has a multilayer comb-shaped structure at its top for generating CP fields. Three dielectric strips are embedded inside the DRA body to support multiple transverse-electric (TE) DRA modes to widen the DRA bandwidth. To slightly improve the axial-ratio (AR) performance, the DRA is twisted in the horizontal plane. For demonstration, a prototype operating in C-band was designed and printed with two different materials. The reflection coefficient, AR, radiation pattern, antenna gain, and efficiency of the antenna are measured, and reasonable agreement between the measured and simulated results is observed. The prototype has a measured 10 dB impedance bandwidth of 69.7% (4.80–9.94 GHz) and 3 dB AR bandwidth of 68.6% (4.52–9.24 GHz), achieving a wide overlapping bandwidth of 63.2% (4.80–9.24 GHz). Both the AR and overlapping bandwidths are record-high for a single-fed CP DRA. The prototype has a measured peak antenna gain of 8.3 dBic inside the overlapped passband. [ABSTRACT FROM AUTHOR]

A substrate integrated waveguide (SIW) H-plane horn antenna loaded with tapered multistrip transition and dielectric slab is proposed for broadband high-gain operation. The broadband characteristic of the proposed antenna is obtained by loading a tapered multistrip transition. The theory of coupled resonator is introduced to reveal the mechanism of bandwidth enhancement. On the other hand, a dielectric slab is used to enhance the gain of the proposed antenna. The optimal length of this dielectric slab is determined based on the design principles of a dielectric rod with maximum gain. Besides, the tapered multistrip transition also contributes to the gain improvement by suppressing the feed radiation and prompting the transverse expansion of the surface wave. To verify the design theory and concept, a prototype operating at the K- and Ka-bands is fabricated and measured. The measurement results show that the impedance bandwidth of the proposed antenna is from 20.6 to 38.4 GHz (60%). Within the operating band, a peak realized gain of 19.1 dBi and excellent endfire radiation patterns with low cross polarization (<−30 dB) and high front-to-back ratio (FBR >20 dB) are achieved simultaneously. With its broad bandwidth, high gain, low cross polarization, and high FBR, the proposed antenna is promising for various millimeter-wave applications. [ABSTRACT FROM AUTHOR]

Silicon photonics (SiPh) shows considerable potential as a radiation-hard technology for building the optical data transmission links for future high-energy physics (HEP) experiments at CERN. Optical modulators are a key component of optical links, which will need to withstand radiation doses in excess of 10 MGy. The geometrical parameters and doping concentrations of two popular types of SiPh modulators, Mach–Zehnder and ring modulators (RMs), have been varied in order to study their impact on the device radiation tolerance. They were exposed to an X-ray beam to test their resistance to ionizing radiation. The RM with the highest doping concentration is shown to be the most tolerant, showing no degradation in performance up to the highest dose of 11 MGy. Moreover, we report first evidence of the dependence of the radiation tolerance on the RM operating temperature. [ABSTRACT FROM AUTHOR]

Blast loading is associated with relatively short duration and high amplitude of forces, which when comes in contact with the reinforced concrete (RC) slabs results in the strong vibrations that yields high internal stresses and relatively larger deflections within the slabs. In this study, behaviour of a typical residential RC slab, when subjected to indoor confined blast, was investigated numerically using the conventional weapons (CONWEP) model available in the finite element software ABAQUS. For this purpose, the blast effect produced due to the gas leakage in a pipe was considered for studying the influence of different parameters which include concrete compressive strength, thickness of the slab, reinforcement ratio and spacing, the standoff distance and the boundary conditions of the RC slab. It was observed that the behaviour of the RC slabs, when subjected to blast loading, significantly differ from that observed under static loading as the latter was found to be associated with the overall bending of the slab, whereas for the case of blast loading the behaviour is characterized by both local damage in the direct contact zone of the slab and detonation and overall bending response. Maximum deflections were found to be more affected by concrete compressive strength, slab thickness and standoff distance. A relationship was proposed for the estimation of central deflection which correlates well with the values obtained from nonlinear FE analysis. [ABSTRACT FROM AUTHOR]

This paper presents the application of a thick-shell nonlinear finite element analysis procedure to estimate the punching shear resisting performance of reinforced concrete slab-column connections under variable connection shear stress conditions. In the analyses performed, varied connection shear stress conditions stem from slabs being supported by columns with different cross-section aspect ratios, being subjected to different distributions of gravity loading, being constructed with different planar reinforcement ratios in orthogonal directions, as well as the application of unbalanced bending moments. Forty-eight isolated slab-column connection specimens presented in the literature were modelled and analyzed using a thick-shell finite analysis procedure. All numerical results were developed using a predefined set of material models and analysis parameters, a consistent meshing procedure, and are shown to provide meaningful agreement with experimental data without the need for case-specific model calibration or the adoption of specialised failure criteria. The results show that thick-shell modelling methods can be suitable for estimating the punching shear response of slabs subjected to non-uniform shear stress development in connection regions, and can provide similar levels of precision to that obtained for the analysis of idealised slab-column connections typically used for design procedure and model development. • Low-cost shell FEA for punching shear assessment of reinforced concrete flat plates. • Analysis of 45 non-idealised connection specimens representative of real-world construction. • Good agreement between FEA simulations and reported results without model calibration. • Result accuracy comparable to that obtained for more typical idealised connection specimens. [ABSTRACT FROM AUTHOR]

The basic features of surface dual modes are investigated on the plasma slab. The integral of kinetic wave dispersion relation is evaluated to derive the wave frequency as well as the relevant Landau damping decrement of the electrostatic surface modes by employing the functional perturbation (FP) method. The influence of the ion thermal motion and geometrical effects is examined on the damping rate of surface dual modes. It is shown that the damping rate is an increasing function with the ion temperature, as this effect becomes more important for middle values of the wavenumbers. It is also shown that the propagation of the surface waves in plasma slab is more difficult than that of the semi-infinite plasma due to their interaction with the additional boundary conditions. We found that the spectral analysis of the surface modes plays a vital role as a diagnostic tool to account for the geometrical effects on the surface waves. [ABSTRACT FROM AUTHOR]

A universal equation for the charge-voltage characteristics in the multigate metal oxide semiconductor (MOS) structure with an arbitrary cross section is presented. A generalized coordinate is proposed and the Poisson equation is integrated with a weighting factor related with the generalized coordinate and the electric field. A compact charge model is derived and analytic and numerical examples for various MOS structures are shown. [ABSTRACT FROM AUTHOR]

The recent failure of buildings because of punching shear has alerted researchers to assess the reliability of the punching shear design models. However, most of the current research studies focus on model uncertainty compared to experimentally measured strength, while very limited studies consider the variability of the basic variables included in the model and the experimental measurements. This paper discusses the reliability of FRP-reinforced concrete slabs' existing punching shear models. First, more than 180 specimens were gathered. Second, available design codes and simplified models were selected and used in the calculation. Third, several reliability methods were conducted; therefore, three methods were implemented, including the mean-value first-order second moment (MVFOSM) method, the first-order second moment (FOSM) method, and the second-order reliability method (SORM). A comparison between the three methods showed that the reliability index calculated using the FOSM is quite similar to that using SORM. However, FOSM is simpler than SORM. Finally, the reliability and sensitivity of the existing strength models were assessed. At the same design point, the reliability index varied significantly. For example, the most reliable was the JSCE, with a reliability index value of 4.78, while the Elgendy-a was the least reliable, with a reliability index of 1.03. The model accuracy is the most significant parameter compared to other parameters, where the sensitivity factor varied between 67% and 80%. On the other hand, the column dimension and flexure reinforcement are the least significant parameters compared to other parameters where the sensitivity factor was 0.4% and 0.3%, respectively. [ABSTRACT FROM AUTHOR]

High‐power laser sources are widely used in industrial precision processing and act as a new platform for strong‐field physics research using peak power over petawatt. This review focuses on realizing high‐energy solid‐state disk and slab systems and the nonlinear‐suppression strategies for high‐power fiber systems using the functional fibers. First, the implementations and enabling technologies of the solid‐state lasers for increasing peak power from gigawatt to petawatt are reviewed. Then the mechanisms and suppression strategies of the deterioration effects (including stimulated Raman scattering, stimulated Brillouin scattering, and transverse mode instability) in various fiber amplifiers are analyzed. At the same time, the mechanism and achievements of the current functional fibers are introduced. Finally, the challenges and perspectives of high‐power solid‐state and fiber amplifiers are summarized. [ABSTRACT FROM AUTHOR]

The transformation optics (TO) technique has been widely applied in the volume reduction of Luneburg lens (LL) in both optical and microwave regimes. However, it is found that the focus is usually not located on the surface of the transformed LL anymore after applying TO. The focus location shift results in a limited volume reduction, severe reflection from the new lens surface, and limited scanning range with increased spillover loss. This article theoretically studies and proposes a TO-based LL antenna with zero focal length by considering the phase mismatch caused by space discontinuity. The study first reveals that the transformation of an LL alone without sustaining the original boundary inherently deteriorates the original focusing property even before exerting any approximation. To validate the idea, a flat metamaterial LL antenna using TO is proposed, approximated, and fabricated using an integrated dielectric and conductive 3-D printing manufacturing process. The feeding patch antenna remains on the surface of the transformed lens. The thickness of the proposed antenna is reduced to 1/3 of a traditional LL in its boresight, while a ±20° beam scanning range is achieved with linearly shifted feedings. The study verifies that it is essential to ensure phase matching at the radiation boundary to maintain the original focusing property of an LL. The information derived from the study evidences the conditions of the enforcement of TO in electromagnetic problems such as dielectric lenses. [ABSTRACT FROM AUTHOR]

A wideband omnidirectional circularly polarized (CP) antenna using a conformal artificial anisotropic polarizer is proposed for millimeter-wave applications. The antenna consists of three parts: an omnidirectional linearly polarized (LP) radiator, an annular hyperbolic lens, and a conformal anisotropic polarizer. The annular hyperbolic lens regulates the spherical wavefront from the LP radiator into a cylindrical shape prior to propagating into the conformal artificial anisotropic polarizer. Each curved slab of the polarizer is conformally tilted 45° to the incident electric field. Therefore, the conformal polarizer is the three-dimensionalization of the 2-D planar artificial anisotropic polarizer. The polarizer designing methodology is the first of its kind to generate wideband CP wave omnidirectionally. The hyperbolic lens and the conformal polarizer are fabricated together using stereolithography (SLA) 3-D printing technology. The measurement results show that the antenna has a wide operating bandwidth of 45% (from 24 to 38 GHz), which completely covers potential 5G 28 GHz spectra. The proposed design has a low fabrication complexity and brings possibilities for high-speed wireless communications using circular polarization. [ABSTRACT FROM AUTHOR]

The melting at the magnesium/aluminum (Mg/Al) interface is an essential step during the fabrications of Mgâ€"Al structural materials and biomaterials. We carried out molecular dynamics simulations on the melting at the Mg/Al interface in a Mgâ€"Alâ€"Mg nanolayer via analyzing the changes of average atomic potential energy, Lindemann index, heat capacity, atomic density distribution and radial distribution function with temperature. The melting temperatures ( T m ) of the nanolayer and the slabs near the interface are significantly sensitive to the heating rate ( v h ) over the range of v h  ≤ 4.0 K psâˆ'1. The distance ( d) range in which the interface affects the melting of the slabs is predicted to be (âˆ'98.2, 89.9) Ă... at v h â†' 0 , if the interface is put at d  = 0 and Mg (Al) is located at the left (right) side of the interface. The T m of the Mg (Al) slab just near the interface (e.g. d = 4.0 Ă...) is predicted to be 926.8 K (926.6 K) at v h â†' 0 , with 36.9 K (37.1 K) below 963.7 K for the nanolayer. These results highlight the importance of regional research on the melting at an interface in the nanolayers consisting of two different metals. [ABSTRACT FROM AUTHOR]

A nonlinear optimization algorithm has been described for the inversion of gravity data profile by a faulted 2-D horizontal thin block. The algorithm simultaneously optimizes for the depth to the center ($z$) of the faulted block, the amount and direction of dip ($\theta $) of the fault plane, and the amplitude coefficient ($A$), which is dependent on the amount of throw $t$ and the density contrast $\Delta \rho $ of the block. The objective functional of this algorithm coupled with both the space of logarithmed absolute values of the observed and predicted gravity data and the space of logarithmed [ $\log (z)$ , $\log (|A|)$ , and $\log (\theta $)] model parameters is the basis of the new inversion scheme introduced here. It has been found essential that the objective functional of this scheme be formulated in this particular combination so that the iterative solver/minimizer (the Gauss–Newton (GN) method) can converge. The developed scheme has been successfully verified on numerical models without noise and achieved superior convergence. It is found stable and can determine the inverse parameters of the faulted block with acceptable accuracy when applied to data contaminated with insignificant noise levels and/or geologic interference. In order to investigate the usefulness of the developed scheme, a published gravity profile has been inverted and analyzed, suggesting new results that are of some geologic significance. The computational efficiency, thorough analysis of the investigated numerical examples, and comparisons of the real data inverted in this paper have demonstrated that the scheme developed here is advantageous to the existing gravity data inversion schemes that solve for the characteristic inverse parameters of a faulted thin block. [ABSTRACT FROM AUTHOR]

Nowadays, there is a strong interest in miniature and high-power vacuum electron devices (VEDs) operating in millimeter and sub-THz bands. VED sources of coherent sub-THz radiation are required for many applications, especially for future advanced high-data-rate telecommunication systems. In this work, we present the results of design study of a meander-line slow-wave structure (SWS) suitable for multiple-sheet-beam operation to achieve a high level of output power. The results of cold-test electromagnetic simulation show a possibility of operation at beam voltage of 12 kV with high values of interaction impedance up to $12 \Omega $. The 3-D particle-in-cell simulation of performance of the traveling-wave tube with 400-mA, 12-kV multiple sheet electron beam predicts up to 26-dB gain and up to 376-W output power. [ABSTRACT FROM AUTHOR]

The task assignment problem (TAP) is concerned with assigning a set of tasks to a set of agents subject to the limited processing and memory capacities of each agent. The objective to be minimized is the total assignment cost and total communication cost. TAP is a relevant model for many practical applications, yet solving the problem is computationally challenging. Most of the current metaheuristic algorithms for TAP adopt population-based search frameworks, whose search behaviors are usually difficult to analyze and understand due to their complex features. In this work, unlike previous population-based solution methods, we concentrate on a single trajectory stochastic local search model to solve TAP. Especially, we consider TAP from the perspective of a grouping problem and introduce the first probability learning-based local search algorithm for the problem. The proposed algorithm relies on a dual probability learning procedure to discover promising search regions and a gain-based neighborhood search procedure to intensively exploit a given search region. We perform extensive computational experiments on a set of 180 benchmark instances with the proposed algorithm and the general mixed integer programming solver CPLEX. We assess the composing ingredients of the proposed algorithm to shed light on their impacts on the performance of the algorithm. Note to Practitioners—This work is motivated by the problem of program modules designing and task allocation in parallel and distribution systems. It can also be applied to deal with job (task) grouping problems in practical industrial applications. This article presents a novel and effective learning-based local search algorithm to obtain high-quality solutions for the considered problem. The results of numerical experiments and comparisons show that our algorithm can achieve good search performances on problem instances of different scales and difficulties. Afterward, we use the proposed solution method to solve a real-life open-order slab assignment problem, which is derived from the production planning of silicon steel for an iron and steel company. The learning techniques of the proposed algorithm are of general interest and can be used in search algorithms for solving other real-life optimization problems with grouping features. For future research, we will design solution methods based on these learning techniques to address other practical optimization problems. [ABSTRACT FROM AUTHOR]

Field-matching technique and kinetic theory of plasma have been used to investigate the dispersion relation of the electrostatic surface plasma modes. We considered a configuration of two identical plasma slabs separated by a vacuum spacer with the rest of space being vacuum. In the limit $k\to 0$ , where $k$ is the propagation constant along the interface, the dispersion relation of surface plasma waves of hot and warm plasma slabs shows the emergence of asymmetric surface plasma modes with frequency starting from the electron plasma frequency $\omega _{\mathrm{ pe}}$ and symmetric surface modes starting from zero frequency. As $k$ increases, the frequencies of surface modes approach a common value, and the surface plasma modes become degenerate at a frequency above the cold plasma quasi-resonance frequency of a single plasma–vacuum interface $\omega _{\mathrm{ sp}}=\omega _{\mathrm{ pe}}/\sqrt {2}$. The two surface plasma modes of each branch of the dispersion relation are localized each near one of the two slab surfaces. By virtue of the finite slab widths, the two surface modes interact via the overlap of their evanescent fields to form asymmetric and symmetric pair of fields. The disagreement between the warm and hot plasma theories in the limit of large wave phase velocity compared with the thermal speed of electrons is due to the difference in their thermal dispersions. The surface plasma modes for hot plasma slabs are heavily Landau damped with negative frequency imaginary parts that overlap for small Debye lengths compared with the plasma width. [ABSTRACT FROM AUTHOR]

Linking authors of short-text contents has important usages in many applications, including Named Entity Recognition (NER) and human community detection. However, certain challenges lie ahead. First, the input short-text contents are noisy, ambiguous, and do not follow the grammatical rules. Second, traditional text mining methods fail to effectively extract concepts through words and phrases. Third, the textual contents are temporally skewed, which can affect the semantic understanding by multiple time facets. Finally, using knowledge-bases can make the results biased to the content of the external database and deviate the meaning from the input short text corpus. To overcome these challenges, we devise a neural network-based temporal-textual framework that generates the subgraphs with highly correlated authors from short-text contents. Our approach, on the one hand, computes the relevance score (edge weight) between the authors through considering a portmanteau of contents and concepts, and on the other hand, employs a stack-wise graph cutting algorithm to extract the communities of the related authors. Experimental results show that compared to other knowledge-centered competitors, our multi-aspect vector space model can achieve a higher performance in linking short-text authors. In addition, given the author linking task, the more comprehensive the dataset is, the higher the significance of the extracted concepts will be. [ABSTRACT FROM AUTHOR]

This study investigated the flexural performance of one-way reinforced concrete (RC) slabs strengthened with two distinct strengthening systems: near – surface mounted (NSM) bars and externally bonded (EB) carbon fiber-reinforced polymer (FRP) strips. The NSM bars comprised four types: carbon FRP (CFRP), basalt FRP (BFRP), glass FRP (GFRP), and stainless – steel (SS) bars. The NSM – strengthened slabs showcased substantial enhancements in yield and ultimate load capacity, ranging from 20 % to 55 % and 59–123 %, respectively. In comparison, those strengthened with EB – CFRP strips displayed increases from 46 % to 107 % and 45–177 %, respectively, depending on the axial stiffness ratio of the strengthening system provided. Furthermore, the slabs reinforced with NSM–BFRP bars showed an 11–25 % improvement in their ductility indices. In contrast, the slabs reinforced with EB experienced a decrease in ductility ranging from 38 % to 50 %. This reduction was attributed to the differences in the modes of failure observed in both strengthening systems. The rupture of the NSM–FRP bars and the strain readings associated at the end of testing confirmed that the tensile strength of the NSM–FRP bars was fully exploited whereas the EB–CFRP strips utilized only 29–36 % of their ultimate tensile strain due to debonding. A finite element (FE) model was formulated to anticipate the behavior of the strengthened slabs. A strong correlation between the numerical predictions and the experimental outcomes was observed. The experimental–to–numerical ratios of the ultimate load ranged between 1.0 and 1.08 for the NSM–strengthened slabs and between 0.98 and 1.38 for the EB–strengthened slabs. This validated the FE models' ability to capture the nonlinear performance of the strengthened slabs. • Effectiveness of NSM-FRP varied based on the type of FRP bars. • NSM-FRP bars increased yield and ultimate loads up to 55 and 123 %, respectively. • NSM-strengthened slabs exhibited improved ductility with indices increasing up to 25 %. • EB-strengthened slabs failed due to debonding of the CFRP strips. • NSM-FRP systems are more effective in restoring the ductility of RC slabs. [ABSTRACT FROM AUTHOR]

In this communication, a phased array antenna with an integrated metasurface is designed to achieve wideband and wide-angle scanning. Generally, the coupling between adjacent elements changes significantly as the scanning angle increases, resulting in limited scanning coverage. Two mutually perpendicular metasurface slabs are designed to achieve wide-angle scanning. The mutual coupling is reduced by properly tuning the dimension of the metasurface. Two perpendicular linear arrays were fabricated to verify the design. The measured 3 dB beamwidth of the active element pattern (AEP, in the array environment) with the integrated metasurface is about 150° in the E-plane and 109° in the H-plane, which is suitable for wide-angle scanning. The simulated and measured results indicate that the beam can scan from −78° to 78° with a 3 dB gain fluctuation in the E-plane array and a wide frequency range from 10 to 12.5 GHz (22.2%). In the H-plane array, the scan angle ranges from −69° to 69° with a 3 dB gain fluctuation and a relative bandwidth of 11%. [ABSTRACT FROM AUTHOR]

A novel planar dielectric polarizer made of a low-profile high-dielectric-constant material is proposed. Two anisotropic antireflection layers are used on both sides to provide impedance transformation and anisotropy simultaneously. The proposed design uses a high-dielectric-constant material to reduce the overall thickness without severe reflections. The unit cells of the middle layer and the antireflection layer use separate periods for better adapting to the fabrication limitation. A polarizer prototype centered at 24 GHz is designed, fabricated, and measured. The prototype is 3-D-printed by commercial fused-deposition-modeling (FDM) technology using a material with a dielectric constant of 10. Experiments show that the prototype has a 25% operating bandwidth and a thickness of $0.52\lambda _{0}$ ($\lambda _{0}$ is the wavelength in the free space). The design methodology widens the choice for material selection and reduces the dimensions of the dielectric polarizer. [ABSTRACT FROM AUTHOR]

A new architecture is provided for the efficient generation of shaped beams and multiple shaped beams (in amplitude, phase, and polarization), with leaky-wave (LW) metasurfaces (MTSs). Those antennas are usually fed by a surface-wave (SW) launcher, which evenly illuminates the MTS versus azimuth, through a cylindrical SW. When the interest lies in generating pencil beams or particular types of shaped beams, the required radiating aperture field (linked to the Fourier transform of the desired radiation pattern) on the MTS is almost azimuthally symmetric in amplitude. However, for a wide class of shaped beams, the desired aperture field is far from being azimuthally symmetric. This leads to an MTS design in which some sectors exhibit a very small surface impedance modulation. Those sectors tend to leave the SW intact until it reaches the rim of the surface, where the power is either reflected or diffracted at the slab rim. We solve this efficiency problem by reducing the amount of power fed into some sectors, through the use of an array of feeding monopoles. The azimuthal illumination of the feeder should be designed to match the azimuthal asymmetry of the desired aperture field. The corresponding MTS surface impedance is then determined using a method of moments (MoM)-based synthesis technique. Several examples are provided to illustrate the concept. The improvement in terms of antenna efficiency is numerically demonstrated. [ABSTRACT FROM AUTHOR]

In a plasma containing micrometer-size dust particles, nonlinear wave synchronization was investigated experimentally under microgravity conditions on board the International Space Station (ISS). These dust particles were confined into a 3-D cloud, in the vicinity of a diffuse edge of the plasma, which was generated by an inductively coupled radio frequency (RF) glow discharge. A cross-sectional slab of the cloud was imaged using a video camera. The dust-density fluctuations in the slab were characterized using the video image data. A steady and long-lived dust acoustic wave (DAW) was observed to be spontaneously generated in the cloud; it propagated through the dust cloud, which had a gradually varying density distribution. Two kinds of spectral analyses of the wave motion were performed, using Fourier transforms and Hilbert transforms, respectively; these revealed two distinctive spatial domains in the cloud, termed frequency clusters. Within each cluster, waves were found to oscillate at a dominant frequency that remained constant, manifesting mutual synchronization throughout the cluster. Across the two clusters, the dominant frequency exhibited a step-wise change, with a frequency ratio of 2:1, which is consistent with phase-lock conditions for a harmonic synchronization state. [ABSTRACT FROM AUTHOR]

This article presents an analytical and numerical investigation of the radiation features of an interesting class of electromagnetic bandgap (EBG) structures excited by an electric line source. The radiation from 2-D lattices made with lossless dielectric cylinders, typically optimized by using the Bloch analysis of the corresponding 2-D photonic crystals, is originally investigated in terms of leaky waves. A thorough modal analysis of open waveguides, composed of a finite number of periodic chains of circular dielectric rods, is presented, which shows a multiplicity of bound and leaky modes. Two radiation windows are identified and the relevant directive features are described in terms of properly excited dominant leaky modes. The possible excitation of higher order leaky modes and guided modes has been carefully considered, by also capturing the relevant residue contributions in a nonspectral representation of the excited fields. The final results on radiated fields by realistic truncated structures, obtained by ad hoc software as well as full-wave EM simulators, are in excellent agreement with those predicted by the proposed leaky-wave approach. [ABSTRACT FROM AUTHOR]

A reflection approach utilizing an open-ended rectangular waveguide (ORW) for dielectric constant characterization of low-loss slab materials is presented. A calibration technique is proposed to reduce the effects of the higher order mode fields in dominant-mode analysis. In addition, the effects of undesired reflections caused by the finite-sized flange are also reduced in the extraction of the dielectric constant. Moreover, a small perturbation is introduced in the calculation of the reflection coefficient to eliminate the singularities as well. The dielectric constant of material under test (MUT) is extracted utilizing the measured reflection coefficient by assuming that the loss tangent of MUT is zero. Simulation results are presented to validate the calibration process. The selection of suitable airgap thickness and the effects of lossy MUT are also discussed. The measured dielectric constants of MUT made of polymethyl methacrylate (PMMA) and polytetrafluoroethylene (PTFE) are presented as well, which agrees excellently with the results achieved from the free-space method. [ABSTRACT FROM AUTHOR]

We propose a simple and accurate microwave extraction procedure for full electromagnetic characterization of $\Omega $ -class bianisotropic metamaterial (MM) slabs from normal incidence scattering (S-) parameters using TE1, TE2, and TE3 modes. Its closed-form nature (no need for any numerical analysis and optimization toolbox) and less requirement (a total of seven S-parameters) demonstrate the advantage of our method over other methods in the literature. Our approach was validated and its accuracy was verified by S-parameters, through a full electromagnetic simulation program—CST Microwave Studio, of an edge-coupled $\Omega $ -class split-ring-resonator MM slab. [ABSTRACT FROM AUTHOR]

The major axis of the elliptically polarized wave generated by a linearly polarized (LP) radiating source and an artificial anisotropic polarizer has been analyzed in this communication. Both theoretical and experimental results show that the major axis of the elliptically polarized wave generated by such a combination has an angle of 0° or 90° to the E-plane of the LP radiator. The angle between the major axis and the E-plane depends on the phase difference of the two orthogonal electric components after propagating through the polarizer. Measurement has been conducted for verification which covered the entire V-band (50–75 GHz). The result in this communication provides instructions for the usage of artificial anisotropic polarizers in detection and measurement, such as the calculation of the polarization efficiency during transmission. [ABSTRACT FROM AUTHOR]

In an infrared photodetector, noise current (dark current) is generated throughout the volume of the detector. Reducing the volume will reduce dark current, but the corresponding smaller area will also reduce the received signal. By using a separate antenna to receive light, one can reduce the detector area without reducing the signal, thereby increasing its signal-to-noise ratio (SNR). Here, we present a dielectric resonator antenna (DRA)-coupled infrared photodetector. Its performance is compared to a conventional resonant cavity-enhanced slab detector. The noise equivalent power (NEP) is used as a figure of merit for the comparison. Formulas for the NEP are derived for both cases. A pBp photodiode detector is assumed in the comparison. The active region of the photodiode is an InAs/GaSb Type II Superlattice (T2SL). A Genetic Algorithm is used to optimize the dimensions of the detector and the DRA to achieve the smallest NEP. The result is a photodetector that converts over 85% of the incident light into carriers with a volume reduced by 95%. This optimal geometry leads to an NEP reduced by 6.02 dB over that of the conventional resonant cavity-enhanced slab detector. [ABSTRACT FROM AUTHOR]

Patented single-slab self-temperature-compensated air-filled substrate integrated waveguide (AFSIW) cavities and quasi-elliptic filters are proposed and demonstrated in this article. Such components are of high interest for the design of thermally stable circuits and systems on substrate meeting the size, weight, power, and cost (SWaP-C) reduction expected for future systems, especially for space applications. First, a theoretical multiphysics model is presented for the synthesis of single-slab self-temperature-compensated AFSIW cavities. It is demonstrated from theory that by properly choosing the dielectric slab material and dimensions, perfect temperature compensation can be achieved. This extended technique allows the implementation of temperature compensation in any type of cavity, filter, and multiplexer configuration. For demonstration purposes, a single-slab self-temperature-compensated in-line folded seventh-order quasi-elliptic AFSIW filter operating at 12 GHz with a 250-MHz (2.27%) −3-dB bandwidth is designed and fabricated. It achieves a measured unload $Q$ -factor of 992 at ambient temperature (23 °C) and a measured resonance frequency thermal stability as low as 0.58 ppm/°C at −20 °C and 0.89 ppm/°C at 70 °C compared with its temperature-uncompensated counterpart achieving a thermal stability of −15.5 ppm/°C at −20 °C and −17.73 ppm/°C at 70 °C. Furthermore, it is demonstrated in this article that transmission zeros (TZs) created by cross-couplings in the in-line folded configuration of the self-temperature-compensated quasi-elliptic filter achieve a thermal stability of 2.55 ppm/°C and 2.3 ppm/°C (2.34 ppm/°C and 4.37 ppm/°C) at −20 °C (70 °C), in the lower and upper bands, respectively. [ABSTRACT FROM AUTHOR]

Employing non‐metallic reinforcement made of fiber‐reinforced polymers (FRPs) as textile grids is one promising extension of the utilization range of FRP in concrete construction, and thin planar elements reinforced in this manner have high application potential in bridge or parking garage decks, in façades, or in webs and flanges of hollow core cross‐sections. Existing models for predicting the shear resistance of such elements were derived for solid cross‐sectional dimensions similar to conventional steel‐reinforced structures, and their application to thin slabs is debatable. This paper presents the results of an extensive experimental program on the one‐way shear capacity of slabs without and with carbon FPR textile shear reinforcement. A variation of member height, shear slenderness, and shear reinforcement ratio allowed for analysis of the most relevant influencing factors on shear resistance. Both planar and preformed C‐shaped grids enhance the shear capacity and are suitable as shear reinforcement in thin slabs. The experimental results are the foundation for the extension of shear models to thin slabs with FRP reinforcement and for derivation of new unifying shear models that are applicable to a wider range of reinforcement materials and member dimensions. [ABSTRACT FROM AUTHOR]