Compact Band Research Articles

Compact Vital-Sensing Band with Uninterrupted Power Supply for Core Body Temperature and Pulse Rate Monitoring.

Although wearable devices for continuous monitoring of vital signs have undergone significant advancements, their need for frequent recharging precludes continuous operation, potentially leading to adverse outcomes being overlooked. Additionally, the scattered locations of the sensors hamper wearability. Herein, we present a compact vital-sensing band with uninterrupted power supply designed for continuous monitoring of core body temperature (CBT) and pulse rate. The band─which comprises two sensors, a power source (i.e., a flexible thermoelectric generator (TEG) and a battery), and a flexible circuit─is worn on the forearm. The CBT is calculated by measuring the skin temperature and heat flux, while a triboelectric nanogenerator-based self-powered pressure sensor is utilized for pulse rate monitoring. The TEG is a flexible unit that converts body heat into electricity, accumulating a total energy of 314 mJ (100%). Out of this total energy, only 43.2 mJ (7.2%) is utilized for CBT measurements, while the remaining 270.80 mJ (92.8%) is stored in the battery. This enables reliable and continuous operation of the vital-sensing band, highlighting its potential for use in healthcare applications.

A nonlocal kernel-based continuum damage model for compaction band formation in porous sedimentary rock

A nonlocal kernel-based continuum damage model for compaction band formation in porous sedimentary rock

Multiscale simulation study for mechanical characteristics of coral sand influenced by particle breakage

This paper investigates the mechanical response of coral sand under particle breakage using a hierarchical multiscale model combining the discrete element method (DEM) and the finite element method (FEM). This DEM-FEM model links the microscopic interaction mechanisms to macroscopic phenomena such as strain localization and failure. A cohesive contact model was first utilized to simulate compaction bands in the DEM and construct a cohesive assembly with smaller particles distributed around a larger particle to better simulate the grinding and angular breakage of coral sand. A representative volume element (RVE) that includes particle breakage was then constructed and analyzed under periodic boundary conditions. DEM analysis was performed, and the results were compared with triaxial compression test data obtained from the literature, demonstrating that the constructed RVE effectively represents the mechanical properties of coral sand. The constructed RVE was used for hierarchical multiscale simulations, which showed good agreement with existing triaxial testing of coral sand. Finally, by setting a larger cohesive force, the constructed coral sand particles were prevented from breakage, and comparative analysis revealed that particle breakage weakens the mechanical properties of coral sand. Furthermore, different shapes of coral sand particles were constructed, and RVE and hierarchical multiscale simulations of triaxial tests were performed. The results indicated that the triaxial tests of long strip-shaped coral sand particles exhibit higher peak values compared to spherical coral sand particles. Additionally, a double porosity model of coral sand was constructed to analyze the impact of internal porosity on soil mechanical properties. The results showed that the presence of internal porosity significantly weakened the mechanical properties of coral sand. These findings highlight the significant impact of particle breakage and shape on the mechanical behavior of coral sand, offering important insights for engineering applications.

Compact Ultra-Wide Band Two Element Vivaldi Non-uniform Slot MIMO Antenna for Body-Centric Applications

This work presents a novel compact two-port Vivaldi Non-uniform Slot MIMO Antenna (VNSMA) to overcome the challenges of traditional ultra-wideband (UWB) antennas, such as large size, limited bandwidth (BW), high mutual coupling, and suboptimal performance in wearable devices. Designed based on Vivaldi non-uniform slot profile antenna (VNSPA) theory, this antenna offers superior performance metrics and significantly advances wearable antenna technology. The novelty of this work is investigating different positions for the two compact UWB VNSA to get better performance with smaller sizes, wider impedance matching BW, and lower mutual coupling (MC) where side by side at an angle of 180ᵒ is determined to be the best configuration. Detailed parametric studies were performed on this configuration for better performance, where the MC was further reduced by etching the ground plane with a vertical slot between the two antennas and L slots around the Microstrip to Slot (M/S) transition, respectively. Furthermore, BW and gain enhancements were obtained by etching exponential tapered and triangular slots at its two edges. Using the Finite Integration Technique (FIT), Computer Simulation Technology (CST) software is used for the simulations in this work. The VNSMA is tested on a CST Gustav human phantom and gives excellent results with low specific absorption rate (SAR) values at several UWB frequencies. The proposed VNSMA provides good, measured outcomes of S11 < -11.08 dB with wide BW of 12.5 GHz (2.33–14.83 GHz) covering high isolation of -23 dB (for most of frequency band), moderate-high gain of 5.89 dBi, radiation efficiency of 66-90%, low Envelope Correlation Coefficient (ECC) of 0.002 and high diversity gain (DG) of 9.99 dBi, stable radiation patterns, and average group delay of 1.2 ns. This innovative design, which optimizes antenna positioning and incorporates ground plane modifications, achieves remarkable improvements in BW, which covers multiple bands, including WLAN (2.4–2.485 GHz), X-band (8-12 GHz), and part of Ku band (12-18 GHz). The findings demonstrate the antenna's potential for various high-resolution microwave imaging applications, particularly in medical diagnostics like breast and brain cancer detection, showcasing its impact in wearable technology and healthcare.

Enhanced Carrier Transport Performance of Monolayer Hafnium Disulphide by Strain Engineering.

For semiconducting two-dimensional transition metal dichalcogenides (TMDs), the carrier transport properties of the material are affected by strain engineering. In this study, we investigate the carrier mobility of monolayer hafnium disulphide (HfS2) under different biaxial strains by first-principles calculations combined with the Kubo-Greenwood mobility approach and the compact band model. The decrease/increase in the effective mass of the conduction band (CB) of monolayer HfS2 caused by biaxial tensile/compressive strain is the major reason for the enhancement/degradation of its electron mobility. The lower hole effective mass of the valence bands (VB) in monolayer HfS2 under biaxial compressive strain improves its hole transport performance compared to that under biaxial tensile strain. In summary, biaxial compressive strain causes a decrease in both the effective mass and phonon scattering rate of monolayer HfS2, resulting in an increase in its carrier mobility. Under the biaxial compressive strain reaches 4%, the electron mobility enhancement ratio of the CB of monolayer HfS2 is ~90%. For the VB of monolayer HfS2, the maximum hole mobility enhancement ratio appears to be ~13% at a biaxial compressive strain of 4%. Our results indicate that the carrier transport performance of monolayer HfS2 can be greatly improved by strain engineering.

Research on the shear band suppression mechanism in strut-based lattice structures by oblique graded design

Under compressive loads, shear band formation in lattice structures can lead to stress fluctuations, resulting in a decrease in energy absorption capacity. To specifically suppress shear bands, it is necessary to expound the formation mechanisms. This study used theoretical analysis, experiments, and finite element (FE) simulations to elucidate the mechanism underlying shear band formation in strut-based lattice structures. It was determined that stress concentration at strut joints along the 45° diagonal plane induced shear deformation. Shear bands were most pronounced along the four body diagonals, and their existence diminished as the distance from the diagonal increased. Therefore, a design of oblique graded lattice structure (OGLS) was proposed, and quasi-static compression experiments were performed using FE method. The results showed that the main internal stress of OGLS is combined with the original 45° shear stress and the annular staggered stress produced by the oblique graded design, which constrains each other and avoids mutual dislocation deformation, thus realizing shear band suppression. However, an excessively large graded coefficient excessively weakens the 45° shear stress and results in the appearance of an annular compact band. By optimizing the graded coefficient based on the deformation consistency of the outer contour, the optimized OGLS exhibited significant improvements in yield strength, plateau stress, and energy absorption, which are increased by 36.06%, 39.29%, and 34.41%, respectively. This research offers novel perspectives on how lattice structures can attain stable compression deformation and a high energy absorption capacity.

Development of Compaction Localization in Leitha Limestone: Finite Element Modeling Based on Synchrotron X‐Ray Imaging

AbstractThe mechanical behavior and failure mode of porous rocks vary with their microstructures. The formation of compaction bands (CBs) has been captured with high precision via in situ synchrotron CT and kinematic characteristics can be attained by image analysis. However, the stress characteristics cannot be directly evaluated from images, and how porosity heterogeneity triggers local instability and leads to the formation of CBs is not yet fully understood. To address this problem, we established a finite element (FE) model of the solid skeleton of a Leitha limestone sample based on X‐ray μCT data, considering the heterogeneity of pores and plastic hardening, and reproduced the evolution of strain localization and CBs. Our results revealed that the heterogeneity of porosity has a profound influence on the formation and propagation of CBs. Precursory stresses always appear very early around the pores where compaction bands develop, and the stress state of most points in CBs is quasi‐uniaxial compression, which has significantly high maximum principal stress σ1 in a direction subparallel to the sample axis, causing yield then compaction failure. Also, using a simplified FE mesh and ignoring the fracture of particles underestimate the extreme stress and porosity reduction—these can be improved by using fine mesh and involving grain‐scale fracture mechanics. Our study proves the feasibility and reliability of the CT‐FE simulation scheme, which can be extended to investigating the stress distribution and evolution of different rock types with a spectrum of failure modes if in situ CT data of rock deformation is available.

Nigella sativa Oil-loaded Ethanolic Vesicular Gel for Imiquimod-induced Plaque Psoriasis: Physicochemical Characterization, Rheological Studies, and In vivo Efficacy.

The therapeutic effect of NS oil in mild to moderate psoriasis is limited owing to low play load of thymoquinone ( &#60; 15 %w/w), irritation, dripping, low viscosity and thus, less contact time on the lesions. This study aimed at developing and characterizing the ethanolic vesicular hydrogel system of Nigella sativa (NS) oil (NS EV hydrogel) for the enhancement of anti-psoriatic activity. The objective of this study was to develop NS EV hydrogel and evaluate its anti-psoriatic activity. The identification and quantification of TQ content in different NS seed extracts and marketed oil were measured by an HPTLC method using n-hexane and ethyl acetate as solvent systems. Preparation of ethanolic vesicles (EVs) was performed by solvent injection method, while its antipsoriatic activity was evaluated employing an Imiquad (IMQ)-induced plaque psoriasis animal model. A compact HPTLC band was obtained for TQ at an Rf value of 0.651. The calibration plot was linear in the range of 1-10 μg/spot, and the correlation coefficient of 0.990 was indicative of good linear dependence of peak area on concentration. From the different NS sources, the high TQ content was obtained in the marketed cold press oil, i.e., 1.45±0.08mg/ml. Out of various NS oilloaded EVs, the F6 formulation revealed the smallest particle size (278.1nm), with log-normal size distribution (0.459) and adequate entrapment efficiency. A non-uniform shape was observed in the transmission electron microscopy. The viscosity of F6 formulation hydrogel was 32.34 (Pa·s), which exhibited plastic behavior. In vivo, efficacy studies demonstrated decreased inflammation of the epidermis and dermis and a marked decrease in the levels of IL-17 by NS EV hydrogel compared to plain NS oil and standard drugs (Betamethasone and Dr. JRK Psorolin Oil). It may be concluded from the findings that NS-loaded EV gel was as good as betamethasone cream but more efficacious than the other treatments.

Lattice distortion dependent physical and mechanical properties of VCoNi multi-principal element alloys

Multi-principal element alloys (MPEAs) have garnered widespread recognition owing to their remarkable mechanical properties. Among alloying elements, the vanadium (V) element exhibits unique characteristics and has a high strengthening effect in the face-centered cubic Co-Ni-V MPEAs family owing to its large atomic radius. Here, first-principle calculations are utilized to examine the physical and mechanical characteristics of extensively researched VCoNi MPEAs. The objectives of this work are to give guidance on the design of MPEAs with desirable capabilities and fresh insight for understanding the role of lattice distortion described by atomic size difference on lattice parameters, binding energy, generalized stacking-fault energy, elastic properties, and electronic properties. A high degree of lattice distortion can lead to an increase in lattice constants, a more stable structure, and enhanced plasticity. These trends are attributed to a shortened pseudo-energy gap, large variations in charge density difference, and compact band overlap with increasing lattice distortion. The above results aim to serve as a point of reference for exploring the physical and mechanical attributes of MPEAs.

Compact Ultra Wide band Modified Circular Robo type Antenna for C – V2X application

Compact Ultra Wide band Modified Circular Robo type Antenna for C – V2X application

A compact ultra-wide band fractal antenna for breast cancer detection applications

A compact ultra-wide band antenna for breast cancer detection in bio-medical applications is presented in this study. The proposed antenna is printed on 1.6 mm thick FR4 substrate with a dielectric constant of 4.6 and tangential loss of 0.02. The uniform ground plane on the substrate (PCB) has been altered by shortening its length and making minimal changes to its side edges in order to improve overall bandwidth. The suggested antenna is functioning from 3 to 10.2 GHz which covers the ultra-wide band recommended by Federal Communication Commission (FCC) over the 10 dB impedance bandwidth. Additionally, the antenna has a significant overall gain of 3.2 dBi and an overall radiation efficiency of between 89 % and 92 %. Furthermore, the antenna maintains a uniform radiation pattern across its operating band. Parametric research has been conducted on the different parameters to tune the antenna into the required operating band, and placement analysis of the antenna is then investigated by assessing specific absorption rate (SAR).

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.

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.

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 &lt; 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.

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.

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

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.