H-shaped Structures Research Articles

Low-voltage-tunable electromechanical photonic directional coupler in silicon nitride for telecom wavelengths.

Silicon nitride is a low-loss photonic integrated circuit (PIC) platform. However, silicon nitride also shows small nonlinear optical properties and is dielectric, which makes the implementation of programmability challenging. Typically, the thermo-optic effect is used for this, but modulators based on this effect are often slow and cross talk-limited. Here, we present a different approach to programmability in silicon nitride photonics. Micro-electromechanical elements are added to a photonic directional coupler, forming two H-shaped structures. The coupling can be changed by applying a voltage to electrodes placed onto the H-structure, which are then attracted by an electrostatic force. These suspended directional couplers show an insertion loss of 0.67 dB and demonstrate switching with 1.1±0.1 µs rise times, representing a valuable addition to the thermal photonic modulators in silicon nitride technology that offer higher modulation speeds while keeping a comparable insertion loss.

A dual operating (27/38 GHz) high performance 2 × 4 MIMO antenna array for 5G new radio applications

This article presents an unique configuration of Multiple-Input Multiple-Output (MIMO) antenna array for functioning at 27/38 GHz millimeter-wave 5G new radio (NR) frequency bands applications. The suggested antenna is constructed with four MIMO elements, containing total of eight identical patches arranged in a 2 × 4 array configuration. The array also includes a separate non-connected rectangular ground plane with an overall dimension of 32.4 × 32.8 × 0.8 mm3. The single radiating patch elements are designed using spline resonator with H-shaped structures. The prototype model is realized using low cost FR-4 substrate and the obtained measurement results validate the analyzed simulated results. The suggested MIMO array antenna offers dual band operation with an impedance bandwidth of 8400 MHz covering 22 to 30.4 GHz and 8500 MHz ranging from 36.1 to 44.6 GHz. The proposed antenna achieves a peak gain of 8.75 dBi when operating at 27 GHz and 18.59 dBi at 38.1 GHz. Furthermore, it shows circular polarization characteristics by offering the axial ratio values significantly lower than 3 dB at 27 GHz and 38.1 GHz frequency bands. Additionally, the results indicate the favourable values of the diversity performance parameters with reference to Mean effective gain (MEG), Envelope correlation coefficient (ECC), Diversity gain (DG), Total active reflection coefficient (TARC), and Channel capacity loss (CCL). Moreover, it demonstrates high isolation (<−20 dB) within the desired bandwidth. These superior characteristics make it compatible for 5G NR frequency bands N257(26.5-29.5 GHz), N258 (24.5-27.5 GHz), N259 (39.5-43.5 GHz) and N260 (37-40 GHz), enabling its use in various countries including the China, European Union, Sweden, Korea, Japan, United States of America, Canada and Australia.

Piezoelectric ceramic sensor-based structural health monitoring of diagonally braced H-shaped steel structures

In this study, we propose a piezoelectric ceramic sensor-based health monitoring method to monitor the stress state of diagonally braced H-shaped steel structures. Loading experiments were carried out on diagonally braced H-shaped steel under different working conditions. Subsequently, the amplitude and energy of piezoelectric signals under these two working conditions were compared and analyzed, and finite element analysis was performed using ABAQUS software to verify the results. The experimental results showed that with an increase in the web height or load, the time-domain waveform energy index of the H-shaped steel increased. Under different working conditions, such as a diagonally braced H-shaped steel member with a web height of 10 cm, when the pressure value was less than 10 N/mm2, the energy index increased by approximately 15.98% for every 1 N/mm2 increase in the pressure. When the pressure value was greater than 10 N/mm2 and less than 15 N/mm2, the energy index increased by approximately 1% for every 1 N/mm2 increase in pressure. Further, the energy index increased by approximately 8.4% for every 1 cm increase in the height of the web. Simultaneously, it can be seen from the results of the finite element analysis that the stress and strain at the induction position of the piezoelectric ceramic sensor increased with an increase in the external pressure. The study of structural health monitoring for diagonally braced H-shaped steel structures holds significant importance in ensuring the safety and reliability of these structures, achieving predictive maintenance, evaluating structural performance and energy efficiency, and optimizing structural maintenance.

Double-E-Triple-H-Shaped NRI-Metamaterial for Dual-Band Microwave Sensing Applications

This paper presents a new Double-E-Triple-H-Shaped NRI (negative refractive index) metamaterial (MM) for dual-band microwave sensing applications. Here, a horizontal H-shaped metal structure is enclosed by two face-to-face E-shaped metal structures. This double-E-H-shaped design is also encased by two vertical H-shaped structures along with some copper links. Thus, the Double-E-Triple-H-Shaped configuration is developed. Two popular substrate materials of Rogers RO 3010 and FR-4 were adopted for analyzing the characteristics of the unit cell. The proposed structure exhibits transmission resonance inside the S-band with NRI and ENG (Epsilon Negative) metamaterial properties, and inside the C-band with ENG and MNG (Mu Negative) metamaterial properties. A good effective medium ratio (EMR) of 8.06 indicates the compactness and effectiveness of the proposed design. Further analysis has been done by changing the thickness of the substrate material as well and a significant change in the effective medium ratio is found. The validity of the proposed structure is confirmed by an equivalent circuit model. The simulated result agrees well with the calculated result. For exploring microwave sensing applications of the proposed unit cell, permittivity and pressure sensitivity performance were investigated in different simulation arrangements. The compact size, effective parameters, high sensitivity and a good EMR represent the proposed metamaterial as a promising solution for S-band and C-band microwave sensing applications.

Environmental Enrichments in Laying Hen Production Systems with Emphasis on Welfare and Egg Quality

This paper reviews the effects of environmental enrichments in different laying hen production systems on hen welfare and egg quality. To improve hen welfare, several studies have investigated various environmental enrichments that suit different laying hen production systems. The positive results of these studies can enable such environmental enrichments to be utilized in commercial laying hen production. In this review, the most studied environmental enrichments in the free-range production system include forage, shelterbelt, and artificial shade in the outdoor area and novel objects and H-shaped perching structures in the indoor. These are associated with increased range use that positively affects hen welfare. In the aviary system, perches, and litter materials (e.g., straw, sand) as environmental enrichments are linked to improved behavioral expression, reduced stress, and enhanced immune system. Under the litter system, environmental enrichment with substrates (e.g., pecking stones, alfalfa blocks, silage, straw, barley) has been found to increase the foraging behavior of laying hens. This reduces severe feather pecking thus improving the plumage condition of hens. Although the effects of environmental enrichments on hen welfare have been assessed and scientifically proven in the reviewed studies, enough progress of their impact on egg quality traits has not been reported. The studies have shown that environmental enrichments have no significant effect on egg quality traits. On the other hand, appropriate pasture plants as environmental enrichments in the free-range production system in relation to hen welfare and egg quality have not been identified. Therefore, it is important to continue studies on environmental enrichments while emphasizing their influence on egg quality since it is a major performance trait in the egg industry. In addition, there is a need for studies to determine the ideal pasture species in the free-range production system that positively affects hen welfare and egg quality.

Seismic Behaviour of H-Shaped Complex Structures

Seismic Behaviour of H-Shaped Complex Structures

Gemini Thermotropic Smectic Liquid Crystals for Two-Dimensional Nanostructured Water-Treatment Membranes.

We have developed a two-dimensional (2D) liquid-crystalline (LC) nanostructured water-treatment membrane showing high virus rejection ability (over 99.99997% for bacteriophage Qβ) and improved water permeation. Polymerizable gemini amphiphiles have been designed and synthesized. They have H-shaped gemini-type structures of thermotropic smectic liquid crystals composed of cationic imidazolium moieties. One of the gemini amphiphiles shows a smectic A phase with an interdigitated bilayer structure. A cross-linked self-standing 2D nanostructured polymer film has been obtained by in situ photopolymerization of the gemini amphiphile in the smectic phase. The length of linkers in gemini amphiphiles affects the formation of LC phases. The 2D nanostructured membrane also showed selective salt rejection.

Relationships Between Rearing Enrichments, Range Use, and an Environmental Stressor for Free-Range Laying Hen Welfare.

Enrichments during pullet rearing may improve adaptation and welfare of hens as they move from indoor rearing to a free-range system. Individual variation in outdoor ranging may also affect welfare. This study assessed the effects of rearing enrichments and an imposed environmental stressor on hen welfare and egg quality along with the association of welfare with ranging. Hy-Line Brown® chicks (n = 1,386) were reared indoors until 16 weeks with 3 enrichment treatments including a “control” group with standard floor litter, a “novelty” group that received novel objects that were changed weekly, and a “structural” group with H-shaped perching structures. Pullets were then moved to a free-range system with three replicates of each rearing treatment. Daily ranging was individually tracked from 25 to 64 weeks via radiofrequency identification technology. Individual hen welfare assessments were performed at 25, 33, 43, 56, and 64 weeks and correlated with ranging time prior to these dates. At 44 weeks, the range area was reduced by 80% for 11 days to induce stress. Changes in ranging behavior, albumen corticosterone concentrations and egg quality were evaluated. GLMMs showed significant interactions between hen age and rearing treatment for live weight, number of comb wounds, plumage coverage, and toenail length (all P ≤ 0.003), with the enriched hens showing more consistent live weight at the later ages, fewer comb wounds at 33 weeks, and better plumage coverage at the later ages, whereas the structural hens had shorter toenails as age increased. Plumage coverage showed a positive relationship with range use across most age points (P < 0.0001). Hens reduced ranging time following the imposed stressor but increased their number of visits with the lowest increase by the structural hens (P = 0.03). Significant interactions between rearing treatment and stressor for albumen corticosterone concentrations showed the structural hens decreased concentrations immediately post-stress, but the control and novelty groups increased (P < 0.006). The stressor increased or decreased values of most egg quality parameters across all rearing groups (all P ≤ 0.02). Overall, provision of rearing enrichments and greater range use may have positive impacts on hen welfare.

Rearing Enrichments Affected Ranging Behavior in Free-Range Laying Hens.

Within Australia, free-range systems are prevalent, but pullets destined for range access are reared indoors. This mismatch between rearing and layer housing may hinder adaptation to the free-range environment. Rearing enrichments could enhance pullet development. A total of 1,386 Hy-Line Brown® chicks were reared inside an experimental facility across 16 weeks with 3 enrichment treatments including (1) a control group with standard floor-housing, (2) a novelty group providing novel objects that changed weekly (“novelty” hens), and (3) a structural group with custom-designed H-shaped structures including opaque sides (“structural” hens). At 16 weeks of age, all pullets were leg-banded with microchips and moved to an experimental free-range system with 9 identical pens (n = 3/rearing treatment). From 25 to 64 weeks, individual hen daily ranging behavior was tracked via radio-frequency identification technology and grouped into 6 age periods per rearing treatment. Video footage was used to count the number of hens at different distances on the range for the first 14 days of access, and eggs were assessed for albumen corticosterone concentrations 4 days prior to (n = 450) and 1 week after first range access (n = 450). Across most age periods, the structural hens spent the most time ranging (P ≤ 0.01), the novelty hens showed the fewest number of visits to the range (P < 0.0001), and both enriched hen groups had the longest maximum visit durations (P ≤ 0.02). Range use increased with age across all treatments with only 3% of hens never going outside. All hens were initially slow to use the range area with fewer novelty hens venturing farther onto the range (P ≤ 0.03). The structural hens had higher albumen corticosterone concentrations and variance (both P ≤ 0.004) prior to range access. All hens showed an increase in albumen corticosterone following the first week of range access resulting in no differences between rearing treatments in means (P = 0.92) and variance (P = 0.63). Different enrichments have differing impacts on ranging behavior, but further research is needed to understand the mechanisms of effects, with differences in brain lateralization a potential hypothesis to be tested.

Effect of general boundary and coupling conditions on the vibration and power flow characteristics of a coupled H-shaped three-plate structure

Coupled H-shaped three-plate structures are extensively used as support platforms for machinery structures in engineering applications. These structures are constructed with various types of real engineering boundaries and coupling mechanisms. This investigation presents a numerical analysis of the effect of finitely varying boundary and coupling conditions on the vibration and power flow characteristics of a coupled H-shaped three-plate system. Modified Fourier series approximation of out-of-plane and in-plane displacement along with the Rayleigh–Ritz energy minimising procedure has been utilised for theoretical analysis, and different cases of variation of boundary and coupling spring stiffnesses have been taken to numerically analyse its effect on the vibration and power flow characteristics of the plate system. The numerical results indicate the presence of three different zones of finite coupling stiffness combinations at the coupled junction wherein the natural frequency and mode shapes undergo a major alteration. The decay or amplification of power flow characteristics across the plate junctions has been found to be highly dependent on the coupling stiffness values at the junctions. The consideration of general boundaries and coupling conditions in coupled plate systems is an essential design necessity for accurate prediction of the dynamic behaviour of coupled plate structures as their finite variations greatly influence the vibration and power flow characteristics of the coupled system.

Isolation Enhancement in Closely Coupled Dual-Band MIMO Patch Antennas

This letter presents a closely coupled dual-band multiple-input–multiple-output (MIMO) patch antenna that resonates at 3.7 and 4.1 GHz. The MIMO antenna is composed of two mirror-symmetrical single-feed patch antennas that are closely placed with approximately 0.034 λ0 (where λ0 is the wavelength at 3.7 GHz). The decoupling structure consists of the modified array antenna decoupling surface (MADS) and H-shaped defect ground structures for the lower band and upper band, respectively. Through simulation and measurement, the isolation is determined to be greater than 30 dB in both frequency bands, showing a noticeable improvement compared to the original antenna array. Under the effect of the MADS, the measured gain increases by 2.2 and 0.8 dB at the resonance frequencies of 3.7 and 4.1 GHz, respectively. The measured results indicate that the proposed decoupling structure is quite suitable for closely spaced dual-band MIMO antennas.

Tunable plasmon-induced transparency based on asymmetric H-shaped graphene metamaterials**Project supported by the Key Science and Technology Research Project of Henan Province, China (Grant Nos. 162102210164 and 1721023100107) and the Natural Science Foundation of Henan Educational Committee, China (Grant No. 17A140002).

We propose and numerically demonstrate a tunable plasmon-induced transparency (PIT) phenomenon based on asymmetric H-shaped graphene metamaterials. The tunable PIT effect is realized through varying the applied polarization angles rather than changing the structure geometry. By simply adjusting the polarization angle, the transmission spectra can be controlled between the switch-on state and switch-off state. The physical mechanism of the induced transparency is revealed from magnetic dipole inductive coupling and phase coupling. Importantly, by varying the Fermi energy of the graphene or the refractive index of the substrate, the resonant position of the PIT can be dynamically controlled and the maximum modulation depths can reach up to 60.7%. The sensitivity (nm/RIU) of the graphene structure, which is the shift of resonance wavelength per unit change of refractive index, is 5619.56 nm/RIU. Moreover, we also extend our research to the x-axis symmetric H-shaped structure, and the tunable PIT transmission window can also be realized. The physical mechanism of the induced transparency is revealed from the electric dipole hybridization coupling. Our designed H-shaped graphene-based structures is a promising candidate for compact elements such as tunable sensors, switches and slow-light devices.

Tunable multiple plasmon-induced transparency in three-dimensional Dirac semimetal metamaterials

Tunable plasmonic Dirac semimetal metamaterials featuring multiple transparency windows in the terahertz (THz) frequency region are numerically investigated in this study. The proposed multiple plasmon-induced transparency (PIT) system is composed of two types of H-shaped structures, each of which can be regarded as an independent PIT system. Unlike in the conventional metallic PIT systems, the multiple PIT effect in three-dimensional Dirac semimetals can be tuned by varying the Fermi energy instead of the geometrical parameters. The proposed multiple PIT structure could pave the way for potential applications in various areas such as multiple-frequency slow-light devices, optical sensing, and active plasmonic switching.

Heat flux induced coherent vibration of H-shaped single layer graphene structure.

We report an exciting behavior of H-shaped single layer graphene structures subject to a heat flux. H-shaped graphene structures with certain particular dimensions were observed to be able to establish coherent mechanical vibrations in the out-of-plane direction directly from a steady state heat flux flowing from the centerline of the structure towards the two ends. Molecular dynamics (MD) simulation methods together with phonon spectral energy density (SED) analysis techniques were used to obtain the phonon dispersion profiles and identify the low frequency high energy phonon modes. Based on these calculations, we proposed a hypothesis that the mechanical vibration is the result of the superposition of the high energy out-of-plane acoustic (ZA mode) phonons traveling in opposite directions via scattering mechanisms. By using a theoretical model based on the superposition principle, we reproduced the vibrational mode of the graphene structure observed in the MD simulation and verified the proposed hypothesis.

Analysis of Vibration in L- and H-Shaped Planar Frame Structures Using Transfer Function

This paper analyzed the vibration of planar frame structures using the transfer function, which is obtained as the Laplace transform of Green’s function. The transfer function was used to represent the relationship between the excitation (including the initial and boundary conditions) and the response of the system; that is, it can determine the vibration response and stability of the system. The frame was divided into several joint blocks with substructures (beams). A state-space matrix form was used to represent the equation of motion in the beams. The compatibility between the joint blocks and beams allows us to establish the characteristic matrix of the frame, of which the determinant is the characteristic equation. With the eigenvalues obtained as the roots of the characteristic equation, one can establish the eigenfunction of the frame. The receptance of the structure with a single point excitation was also studied. The application of the transfer function to analysis of the L- and H-shaped planar frame structures was conducted in this paper. The results agree well with those published in the literature.

Investigation and Physical Interpretation of H-Shaped Metamaterials in X-Band Waveguide for Microwave Filter Applications

This study numerically and experimentally introduces and investigates H-shaped metamaterials (MTMs) with negative refractive index on the coupling effect of a split ring resonator at the microwave X-band frequencies. The proposed models, consisting of one and two H-shaped MTMs structures, are designed in X-band for modern radar applications. The MTM structures show strong resonance at a range between 8 and 12 GHz. In addition, the effective constitutive parameters are revealed by using a retrieval procedure to verify the negative refraction phenomena of the proposed models. Furthermore, in order to verify the MTM characteristics of the structures, surface current distributions are realized. It can be seen that the structures can be efficiently used for filters, radar applications and so on in a certain frequency regime.

Development and characterization of three-dimensional woven-shaped preforms and their associated composites

Three-dimensional multilayer woven preforms are mostly used in high-performance composite applications due to their better in-plane and out-of-plane mechanical properties. The present study aims to produce and characterize multilayer flax yarn-based three-dimensional-shaped preforms and their corresponding composites. The T- and H-shaped three-dimensional woven preforms were prepared on conventional dobby loom using two types of weaving pattern, i.e., layer-to-layer orthogonal and through thickness orthogonal. Composites were fabricated using open mould technique. Peel strength of T- and H-shaped structures was investigated and compared with laminated structures. Mechanical properties of layer-to-layer-interlocked structures in T and H shapes were found better than TT and laminated structure, both for reinforcement and composite.

Research and Design of Magnetic Substrate Microstrip Antenna with Electromagnetic Band-Gap Structure

Based on the magnetic materials (JV-5) substrate, Double L-shaped slot microstrip antenna is designed. The bandwidth is over 2 times that of the normal substrate and a 40% reduction in size happens.. On this basis, the microstrip antenna with magnetic substrate EBG structure is designed and the EBG structure uses the corrosive effects of joint floor, namely getting periodic H-shaped and circular structures by the floor corrosion, and performing a simulation with HFSS14.0. The results show that the EBG structure of magnetic material having a prominent advantage of the miniaturization and bandwidth-broaden compared to a microstrip antenna with non-magnetic materials substrate, resulting in more than 10% relative bandwidth and a slight gain loss. To some degree, introducing EBG structure can reduce the size of the antenna and increase its bandwidth, and it also improve the gain and radiation characteristics of the antenna.Key words: EBG structure; magnetic material;Double L-shaped slot microstrip antenna; gain

Gain Enhancement for Broadband Vertical Planar Printed Antenna With H-Shaped Resonator Structures

A novel broadband high gain vertical planar printed antenna is presented. The proposed antenna is composed of a bowtie-shaped electric dipole, a loop antenna that works as a magnetic dipole, a microstrip-to-coplanar stripline transition balun, and the H-shaped resonator (HSR) structures that are used for gain enhancement, all of which are printed in the same plane perpendicular to the ground. Prototypes of the HSR-loaded antenna and the unloaded one were fabricated and measured. Analyses and comparisons of the proposed antenna are made. The HSR-loaded antenna has a wide impedance bandwidth of 51.9%, ranging from 2.31 GHz to 3.93 GHz and a stable gain of about 7.4-9.7 dBi over the whole operating band. Compared with the unloaded structure, a gain increment of about 0.5-6.0 dB over the whole band is obtained. The good electrical performances make the antenna suitable for the wireless communication systems and phased arrays.

Synthesis of H-shaped complex macromolecular structures by combination of atom transfer radical polymerization, photoinduced radical coupling, ring-opening polymerization, and iniferter processes

Three controlled/living polymerization processes, namely atom transfer radical polymerization (ATRP), ring opening polymerization (ROP) and iniferter polymerization, and photoinduced radical coupling reaction were combined for the preparation of ABCBD-type H-shaped complex copolymer. First, a-benzophenone functional polystyrene (BP-PS) and poly( methyl methacrylate) (BP-PMMA) were prepared independently by ATRP. The resulting polymers were irradiated to form ketyl radicals by hydrogen abstraction of the excited benzophenone moieties present at each chain end. Coupling of these radicals resulted in the formation of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) with benzpinacole structure at the junction point possessing both hydroxyl and iniferter functionalities. ROP of e-caprolactone (CL) by using PS-b-PMMA as bifunctional initiator, in the presence of stannous octoate yielded the corresponding tetrablock copolymer, PCL-PSPMMA- PCL. Finally, the polymerization of tert-butyl acrylate (tBA) via iniferter process gave the targeted H-shaped block copolymer