Compact Band Research Articles

A Technique for In-Situ Displacement and Strain Measurement with Laboratory-Scale X-Ray Computed Tomography

Abstract Purpose: Establish a technique for simultaneous interrupted volumetric imaging of internal structure and time-resolved full-field surface strain measurements during in-situ X-ray micro-computed tomography (XCT) experiments. This enables in-situ testing of stiff materials with large forces relative to the compliance of the in-situ load frame, which might exhibit localization (e.g., necking, compaction banding) and other inhomogeneous behaviors.Methods: The system utilizes a combination of in-situ XCT, 2D X-ray imaging, and particle tracking to conduct volumetric imaging of the internal structure of a specimen with interrupted loading and surface strain mapping during loading. Critically, prior to the laboratory-scale XCT experiments, specimens are speckled with a high-X-ray-contrast powder that is bonded the surface. During in-situ loading, the XCT system is programmed to capture sequential 2D X-ray images orthogonal to the speckled specimen surface. A single particle tracking (SPT) or digital image correlation (DIC) algorithm is used to measure full-field surface strain evolution throughout the time-sequence of images. At specified crosshead displacements, the motion and 2D image sequence is paused for volumetric XCT image collection. Results: We show example results on a micro-tensile demonstration specimen additive manufactured from Inconel 718 nickel-chrome alloy. Results include XCT volume reconstructions, crosshead-based engineering stress, and full-field strain maps. Conclusion: We demonstrate an in-situ technique to obtain surface strain evolution during laboratory-scale XCT testing and interrupted volumetric imaging. This allows closer investigation of, for example, the effect of micro-pores on the strain localization behavior of additive manufactured metal alloys. In addition to describing the method using a representative test piece, the dataset and code are published as open-source resources for the community. Graphical abstract

A Compact Slot-Loaded Quarter-Wave Patch with Resonance Frequency Formulation for Wi-Fi and Wi-Max Applications

A single layer and compact dual band antenna is presented for the Wi-Fi and Wi-MAX applications. A shorted quarter-wave patch is used to reduce the size. Further, a slot is cut in the non-radiating edge to create additional resonance. The impedance matching at this second resonance is enhanced by cutting a slot in the radiating edge. An equivalent circuit is suggested to explain the behavior of the proposed dual-band antenna. It is confirmed from the numerical calculation that the resonance frequency depends on the lengths l3 and l9 of the structure. The derived formulas provide the value of lengths l3 and l9 according to the user's desired frequency. The dimensions of the antenna are optimized using a commercial full-wave simulator. The concept is verified through measurements. The final design exhibits resonances at 2.44 and 3.33 GHz with a gain of 3.1 and 5.3 dBi, respectively. The cross-pol radiation levels are below 20 dB along the broadside direction.

Reservoir quality of Upper Cretaceous limestones (Ahlen-Fm., Beckum Member, Münsterland Cretaceous Basin): effects of cementation and compaction on the compactable depositional volume

AbstractThe Upper Cretaceous limestones unconformably overlie Upper Carboniferous coal-bearing lithologies and are studied to assess their effect on rising mine-water levels in the Ruhr mining district. Upper Cretaceous sedimentary rocks from the Münsterland Cretaceous Basin have previously been studied regarding their sedimentary structures and fossil content. However, understanding the petrophysical and petrographic heterogeneity in regard to sedimentary properties and their effect on fluid migration pathways is yet missing. Utilizing He-pycnometry, Klinkenberg-corrected air permeabilities, p-wave velocities, transmitted and reflected light analyses, point-counting and cathodoluminescence, we assess the petrophysical, geomechanical and mineralogical properties. Porosity ranges from 1.0 to 18.7% and permeability ranges from < 0.0001 to 0.2 mD, while p-wave velocity ranges between 2089 and 5843 m/s. Mechanical compaction leads to grain rearrangement, deformation of calcispheres, foraminifera and ductile clay mineral laminae. Above and below clay laminae, compaction bands of deformed calcispheres develop. Early diagenetic mineral precipitation of ferroan calcite in inter- and intragranular pores reduces porosity and permeability and influences geomechanical properties. An underestimated aspect of limestone petrography is the relationship of the original primary compactable depositional volume and the influence of compaction, deformation and cementation during early and late diagenesis on reservoir properties. The detrital dominated limestones show an originally high compactable depositional volume (CDV). Overall, reservoir qualities are poor and indicate the sealing potential of the studied lithologies. The Upper Cretaceous (Campanian) limestones thus may act as a barrier for increasing mine-water levels from dismantled, post-mining subsurface hard coal mines in the region. Graphical abstract

Simultaneous measurement of duloxetine hydrochloride and avanafil at dual-wavelength using novel ecologically friendly TLC-densitometric method: application to synthetic mixture and spiked human plasma with evaluation of greenness and blueness

The simultaneous assay of duloxetine hydrochloride (DLX) and avanafil (AVN) in their pure forms, synthetic mixtures, and spiked human plasma was achieved using a novel, eco-friendly, sensitive, and specific HPTLC methodology that have been established and validated. Measuring the levels of co-administered antidepressants and sexual stimulants in biological fluids is an important step for individuals with depression and sexual problems. Separation was performed successfully using pre-coated silica gel 60-F254 as a stationary phase and a mobile phase composed of methanol, acetone, and 33% ammonia (8:2:0.05, v/v/v). Compact bands were produced by the optimized mobile phase that was chosen for development (Rf values were 0.23 and 0.75 for DLX and AVN, individually) after dual-wavelength detection for DLX and AVN at 232 and 253 nm, respectively. The results of polynomial regression analysis were exceptional (r = 0.9999 for both medicines) over concentration ranges of 5-800 and 10-800ng/spot for DLX and AVN, respectively. The quantitation limits were 4.69 and 9.53 ng/spot (0.31 and 0.94 µg/mL), whereas the detection limits were 1.55 and 3.15 ng/spot (0.63 and 1.91 µg/mL), for DLX and AVN, respectively. The International Council for Harmonization (ICH) criteria served as the basis for validating the established approach. Moreover, the proposed technique was evaluated in terms of greenness using four contemporary ecological metrics: The Analytical Greenness software (AGREE), the Green Analytical Procedure Index (GAPI), Eco-Scale, and the National Environmental Method Index (NEMI). Additionally, the Blue Applicability Grade Index (BAGI), a newly developed tool for evaluating the practicality (blueness) of procedures, was taken into consideration when evaluating the sustainability levels of the established approach.

Compaction localization in geomaterials: A mechanically consistent failure criterion

Compaction bands play a key role in the deformation processes of porous rocks and explain different aspects of physical processes in geological formations. The state-of-the-art description of the localized strains that lead to compaction banding has limitations from the mechanical point of view. Thus, we describe the phenomenon using a consistent axiomatic formulation. We build a viscoplastic model using minimal assumptions; we base our model on six principles to study compaction band strain localization triggered by viscous effects. We analyze different stress states to determine the conditions that trigger compaction bands. Laboratory experiments show that a material undergoes different strain localizations depending on the confinement pressure; thus, we perform a series of numerical experiments that reproduce these phenomena under varying triaxial compression conditions. These simulations use a simple viscoplastic constitutive model for creep based on Perzyna’s viscoplasticity and show how confinement changes the strain localization type for different triaxial tests.

Design and development of square stub loaded band pass filter with quality factor analysis

In this paper, a compact square stub-loaded band pass filter (BPF) is designed and investigated for quality factor improvement analysis. A detailed analysis has been presented to demonstrate the superior power handling capability of the proposed microstrip bandpass filter without any degradation in its electrical performance parameters. For this purpose, square-type stubs are incorporated in the proposed bandpass filter which reduced the maximum peak voltage and increased the high peak threshold, instead of using sharp edges. Also, an in-depth analysis of peak voltage with a center frequency of 2.1 and 4.2 have been carried out by considering some parameters like pressure and quality. The proposed bandpass filter shows minimum peak voltage of 1.61 V and 1.59 V across the frequency of 2.1 GHz and 4.2 GHz which covers the application of mobile and radio altimeters. The designed BPF shows the minimum heat generation of 0.29 and 0.89 per watt at the resonating frequencies of 2.1 and 4.2 GHz. Furthermore, the proposed bandpass filter presents an in-depth analysis of several characteristic parameters such as return loss, insertion loss, power loss, delay in group and phase, current distribution, H and E field distribution and maximum power loaded and unloaded quality factor.

Compact quad element dual band high gain MIMO rectangular dielectric resonators antenna for 5G millimeter wave application

In this article, a compact dual-band quad-port Multiple Input Multiple Output (MIMO) Rectangular Dielectric Resonator Antenna (RDRA) with a defected connected ground Geometry (DCGG) for 5G millimeter-wave (mm-wave) application is presented. The antenna is operating at 24 GHz to 32 GHz frequency range. The antenna configuration comprises four identical rectangular microstrip radiators mounted on an RT Duroid 5880 substrate (20 × 20 × 0.254) mm3. To enhance bandwidth, each radiator is equipped with both rectangular and circular-shaped ring slots. To improve the performance of the 4 port MIMO antenna, RDRAs are placed over each radiator and optimized. The MIMO RDRs exhibit dual-band with 4.24 GHz and 0.46 GHz bandwidths. The MIMO RDRA achieves exceptional isolation (>27 dB), high gain (8.24 dB), and more than 94 % radiation efficiency. The diversity parameters exhibit a low Envelope Correlation Coefficient (ECC) of 0.0006, and a high Diversity Gain (DG) of 9.97 dB is achieved, highlighting the effectiveness of the antenna system in providing diversity reception and improving communication reliability in challenging environments. Hence, the proposed MIMO antenna is compact, making it suitable for integration into small 5G devices or systems where space is limited, such as IoT devices, mobile phones, or small base stations at mm-wave frequency bands.

Design of a Dual-band Wearable Antenna Operating at 2.45 GHz and 5.8 GHz for Medical Communication Applications

Indonesia's natural demographic which consists of 16,771 islands makes it has many challenges in infrastructure development, especially in the health sector. According to data, Indonesia currently has 10,203 Puskesmas and 2,449 hospitals. In terms of the number of medical personnel, currently in Indonesia there are 124,449 medical personnel. However, of the large number of medical personnel, 61.12% are concentrated in Java and Bali. This inequality causes the need for a technology that makes it easier for medical personnel to provide services to the community. Wireless Body Area Network (WBAN) is one of developed technology that supports telemedical services. In WBAN, wearable antenna is needed as a transmitter to transmit data. In this paper, a compact wearable dual band antenna was designed in ISM frequency band of 2.45 GHz and 5.8 GHz. A combination of rectangular shape radiating structure and cross slot is constructed to achieve dual band frequency. Jeans Textile material with permitivity of 1.7 and thickness of 1 mm is used for fabricating the proposed antenna. The size of antenna is 52.3mm x 58.69mm. The proposed antenna is simulated with and without human body panthom using cst software. The simulations result indicates that antenna resonates at frequency 2.45 GHz and 5.8 GHz with peak gains of 6.92 dBi and 6.5 dBi. SAR values when the proposed antenna simulated at wrist phantom ​​are 0.326W/kg and 1.024W/kg. When simulated at chest phantom, the SAR values ​​are 0.554W/kg and 0.394W/kg. Therefore, The proposed wearable antenna design is well suited for telemedical services.

A Thermodynamically Based Modified Cam‐Clay Model for Post‐Bifurcation Behavior of Deformation Bands

AbstractCompaction bands are a type of localized deformation that can occur as diffuse or discrete bands in porous rocks. While modeling of shear bands can replicate discrete and diffusive bands, numerical models of compaction have so far only been able to describe the formation of discrete compaction bands. In this study, we present a new thermodynamic approach to model compaction bands that is able to capture both discrete and diffuse compaction band growth. The approach is based on a reaction‐diffusion formalism that includes an additional entropy flux. This entropic velocity regularizes the solution, by introducing a characteristic diffusion length scale and controlling the mode change from discrete to diffusive post‐localisation growth. The approach is used to model compaction band growth in highly porous carbonates. The model can replicate the areas of material damage exhibiting reduced porosity which are often observed as nuclei for the growth of compaction bands in experiments. The model also has the versatility to predict the formation of diffuse compaction bands, which is a significant advance in the field of compaction band modeling. The method can potentially be used for investigating the effect of material heterogeneities on compaction band growth and is heuristic for developing new methodologies for forecasting compaction band formation.

A compact polarization independent stop band frequency‐selective surface for WLAN shielding

AbstractThis paper presents the design and prototype development of a compact frequency‐selective surface (FSS) for shielding WLAN signals. The FSS unit‐cell geometry is evolved by modifying the arms of the conventional crossed dipole element. The footprint of the unit cell is only 6 mm × 6 mm × 1.6 mm. The proposed FSS offers stop band characteristics at 5 GHz for both transverse electric (TE) and transverse magnetic (TM) modes. In addition, the FSS offers angular stability up to 60°. A prototype of the proposed FSS is fabricated and measured to validate its simulations. Measured bandwidth of the stop band is 410 MHz, referenced at −20 dB for both TE and TM modes. Equivalent circuit model of the FSS is derived and the results are compared with the simulations.

Design and analysis of quasi‐lumped notch filter with extended upper pass band

AbstractThis paper presents a hybrid technique‐based compact narrow band stop filter design for broadband applications. It provides the rejection of 60 dB at the centre frequency of 2.25 GHz without any stop band harmonics over the required frequency band of operation, i.e. 1–10 GHz. This filter is highly appropriated for the rejection of undesired bands for RADAR, electronic warfare, and military communications.

Novel design of a compact tunable dual band wireless power transfer (TDB-WPT) system for multiple WPT applications

Novel design of a compact tunable dual band wireless power transfer (TDB-WPT) system for multiple WPT applications

Partial melting in polycrystalline ice: pathways identified in 3D neutron tomographic images

Abstract. In frozen cylinders composed of deuterium ice (Tm+3.8 ∘C) and 10 % water ice (Tm 0 ∘C), it is possible to track melt pathways produced by increasing the temperature during deformation. Raising the temperature to +2 ∘C produces water (H2O) which combines with the D2O ice to form mixtures of HDO. As a consequence of deformation, HDO and H2O meltwater are expelled along conjugate shear bands and as compactional melt segregations. Melt segregations are also associated with high-porosity networks related to the location of transient reaction fronts where the passage of melt-enriched fluids is controlled by the localized ductile yielding and lowering of the effective viscosity. Accompanying the softening, the meltwater also changes and weakens the crystallographic fabric development of the ice. Our observations suggest meltwater-enriched compaction and shear band initiation provide instabilities and the driving force for an enhancement of permeability in terrestrial ice sheets and glaciers.

A wide bandstop filter using negative permeability achieved by complementary electrical L-C resonators

This paper proposes an improved approach for designing a compact microstrip line-based band stop filter (BSF) using a new Z-shaped complementary electrical LC (CELC) resonator with negative permeability. The design offers advantages in terms of compactness and large stopband. The measured insertion loss exhibits a 3 dB bandwidth from 6.7 to 9 GHz, resulting in a relative stopband bandwidth of 28.75% with rejection exceeding 20 dB between 7.5 and 8.2 GHz. Both the simulation and the measurements reveal a high level of selectivity in both the lower and upper transition bands. The final filter has 0.33λg×1.32λg circuit size and is very effective in rejecting unwanted frequency in terms of its selectivity and size.

Compact triple band notched UWB MIMO antenna with integrated GSM

SummaryThis paper introduces an innovative four‐element Ultra‐wideband (UWB) MIMO structure featuring an integrated global system for mobile (GSM) antenna with the ability to achieve dual and triple band‐notch capabilities. The antenna's distinctiveness is achieved through the utilization of four directional meandered line shaping decoupling structures (MLSDS), an orthogonal arrangement, and multi‐slot techniques. The incorporation of orthogonal separation alongside four directional MLSDS significantly reduces the mutual interference between radiating elements. By placing MLSDS on both sides of the substrate, effective coverage of the GSM band is achieved. The development of the MIMO structure unfolds through four distinct phases. The initial stage lacks MLSDS, while the second stage incorporates MLSDS. The third and fourth stages respectively introduce MLSDS with dual and triple notch characteristics. The presence of MLSDS enhances the antenna's impedance bandwidth (IBW). The intended notches are tailored to address interference from bands like Band n41, WLAN, and X‐band. Furthermore, the proposed antenna has undergone simulation, measurement, and comparative analysis with existing models, focusing on diversity performance metrics. The results reveal its exceptional diversity performance, positioning it as a potential choice for creating a portable UWB‐MIMO system.

Estimation of polarization diversity in CPW fed compact dual band dual sense antenna with horn slot structure: 5G and WLAN applications

Estimation of polarization diversity in CPW fed compact dual band dual sense antenna with horn slot structure: 5G and WLAN applications

Acoustic monitoring of compaction in cohesive granular materials.

We study the transition from cohesive to noncohesive states of cemented granular materials (synthetic rocks) under oedometric loading, combining simultaneous measurements of ultrasound velocity and acoustic emission (AE: microseosmicity). Our samples are agglomerates made of glass beads bonded with a few percent of cement, either ductile or brittle. These cemented granular samples exhibit an inelastic compaction beyond certain axial stresses likely due to the formation of compaction bands, which is accompanied by a significant decrease of compressional wave velocity. Upon subsequent cyclic unloading-reloading with constant consolidation stress, we found the mechanical and acoustic responses like those in noncohesive granular materials, which can be interpreted within the effective medium theory based on the Digby's bonding model. Moreover, this model allows P-wave velocity measured at vanishing pressure to be interpreted as an indicator of the debonding on the scale of grain contact. During the inelastic compaction, stick-slip-like stress drops were observed in brittle cement-bonded granular samples accompanied by the instantaneous decrease of the P-wave velocity and AEs which display an Omori-like law for foreshocks, i.e., precursors. By contrast, mechanical responses of ductile cement-bonded granular samples are smooth (without visible stick-slip-like stress drops) and mostly aseismic. By applying a cyclic loading-unloading with increasing consolidation stress, we observed a Kaiser-like memory effect in the brittle cement-bonded sample in the weakly damaged state which tends to disappear when the bonds are mostly broken in the noncohesive granular state after large-amplitude loading. In this paper, we show that the macroscopic ductile and brittle behavior of cemented granular media is controlled by the local processes on the scale of the bonds between grains.

Analysis of Compact Quadruplet Arrow Slotted Notch Band Antenna with Defected Ground Structure

Analysis of Compact Quadruplet Arrow Slotted Notch Band Antenna with Defected Ground Structure

A Compact Novel Quad Patch High Gain Triple Band Microstrip Antenna for 5G/6G mm Wave Applications

This paper presents a compact, novel, quad patch and triple band single substrate microstrip patch antenna for 5G/6G mm wave applications. The aim is to design an antenna within the K-band with three resonance frequencies at 24, 29, and 34 GHz. The antenna is designed on a volumetric dimension of 11×12.7×1.6 mm3. The substrate used is FR4 (dielectric constant 4.4), having a loss tangent of 0.0022. A microstrip line of width 1 mm for a 50 Ω impedance line is used to match with the load antenna, which has four rectangular connected patches. Patch dimensions come from standard antenna equations and simulation done on Ansys High-Frequency Structure Simulator software. Validation of simulated results is done through measurements on the prototype antenna. A substantial good agreement is found between the simulated and measured results. The gain of the proposed antenna is 6.16 dBi, with return loss being ≤-10 dB. Bandwidths are 1.1 GHz (23.8 - 24.9 GHz), 0.9 GHz (28.6 - 29.5 GHz), and 0.8 GHz (33.7 – 34.5 GHz), respectively. The far-field radiation characteristics of both E-plane and H-plane are also reported. The proposed design is suitable for mm wave applications, including smart vehicles, global positioning systems, radio frequency identifications, etc.

High Gain Compact Dual Band Antenna Using Frequency Selective Surface for 5G and WLAN Applications

High Gain Compact Dual Band Antenna Using Frequency Selective Surface for 5G and WLAN Applications