Equivalent Results Research Articles

Comparative Study of OLGA and LedaFlow Models for Mechanistic Predictions of Hydrate Transport Dynamics

Gas hydrate formation in pipelines transporting multiphase fluids from petroleum reservoirs can lead to the formation of blockages, representing a significant flow assurance challenge. Key issues caused by hydrates include substantial increases in the viscosity of mixed liquid phases and the deposition of hydrates on the pipeline wall. This study compares two existing transient multiphase flow simulators, OLGA and LedaFlow, in terms of their estimation of hydrate formation effects on multiphase flow. Here, we compared in detail the hydrate kinetic models, parameters used, and initial condition setup approaches that influence hydrate formation and affect multiphase flow properties. Based on the comparison between the simulation results, it was found that using both simulators with default setups may not lead to comparable results under certain conditions. Adjusting input parameters, such as the stoichiometric coefficient and hydrate formation enthalpy, is necessary in order to obtain equivalent results. Hydrate modules in both simulators have also been applied to a field case. With appropriate setup, OLGA and LedaFlow produce comparable results during steady-state simulations, which align with field observations. This work provides guidelines for setting up OLGA and LedaFlow simulation models to obtain equivalent results.

Three Fields Allelic Haplotype Frequencies of HLA‐DPA1 and ‐DPB1 Typed by Next Generation Sequencing of 563 Families in Chinese Han Population

ABSTRACTThe present study investigated the HLA‐DPA1 and ‐DPB1 allele and haplotype frequencies in the Chinese Han population. A total of 563 families, which have been typed for the purpose of haematopoietic stem cell transplantation, were included, and three‐field allelic resolution typing of HLA‐DPA1 and ‐DPB1 of all individuals were defined by the next‐generation sequencing method. HLA‐DPA1~DPB1 haplotypes were determined by allele segregation within a nuclear family. A total of 9 HLA‐DPA1 and 39 HLA‐DPB1 alleles, and 62 HLA‐DPA1~DPB1 haplotypes were identified. The three most frequent alleles at HLA‐DPA1 locus are HLA‐DPA1*02:02:02 (46.581%), HLA‐DPA1*01:03:01 (36.456%) and HLA‐DPA1*02:01:01 (12.167%); and the three most frequent HLA‐DPB1 alleles are HLA‐DPB1*05:01:01 (34.014%), HLA‐DPB1*02:01:02 (18.428%) and HLA‐DPB1*04:01:01 (10.124%). The three most frequent haplotypes are HLA‐DPA1*02:02:02~DPB1*05:01:01 (32.327%), HLA‐DPA1*01:03:01 ~ DPB1*02:01:02 (14.654%) and HLA‐DPA1*01:03:01~DPB1*04:01:01 (9.458%). The HLA‐DPA1*02:01~DPB1*02:02 and HLA‐DPA1*04:01~DPB1*05:01 haplotypes appear to be unique in Han Chinese. Strong global linkage disequilibrium (LD) between HLA‐DPA1 and ‐DPB1 was confirmed (D′ = 0.848, Wn = 0.684). Moreover, the haplotype frequencies based on the family study were compared with the frequencies estimated by the expectation–maximisation algorithm, and the equivalent results were obtained except for haplotypes with very low frequencies. Our data provide a solid base for HLA‐DP dimer association studies and useful information for transplantation and disease association studies.

A normalized quality of life approach for regulatory approval of medical devices

Abstract Patient-reported outcomes (PROs) are used in clinical trials to provide valuable evidence on the impact of treatment on patients’ symptoms, function and quality of life. High-quality PRO data from trials can inform shared decisionmaking, regulatory and economic analyses and health policy. The heterogeneity between the patient groups and the associated differences in morbidity and quality of life can be taken into account by standardization to the general population. As a result, our study shows that despite the retrospective design with the corresponding level of evidence, mesh repair of a ventral hernia leads to an equivalent result compared to tissue hernia surgery.

Lossy numerical simulation of HRTFs using a linear-logarithmic frequency scale

Acoustic simulations for virtual reality (VR) or augmented reality (AR) require the use of filters designed to model the changes undergone by sound waves emitted from specific points in 3-D space along their path to the subjects' ears, known as head-related transfer functions (HRTFs). Individual HRTFs usually produce more realistic perceptual results, as they account for the specific shape of the listener's body. Numerical simulations in the frequency domain are an attractive option to produce individual HRTFs by computing discrete complex pressure values within regular frequency steps. One of the main disadvantages of this procedure is the high computational power needed, which increases with frequency. Aiming to reduce it, this work explores a new approach that employs a linear-logarithmic hybrid frequency scale. The results obtained for numerical and subjective evaluations (conducted with 23 subjects) suggest that the proposed procedure can produce perceptually equivalent results, even for approximations that save as much as nearly 87% of the original total processing time for the entire audible spectrum.

Acoustic Transmission Loss of a Cylindrical Silencer Filled with Multilayer Poroelastic Materials Based on Mode-Matching Method

The efficacy of silencers in reducing piping noise is contingent upon the specific installation and operating environment. Among the various forms of silencers, the acoustic characteristics of dissipative silencers with sound-absorbing materials attached internally exist in an area that is difficult to explain by existing theories. This is dependent upon the specific type and placement of the attached sound-absorbing materials. This paper presents a methodology for calculating the acoustic transmission loss (TL) of a cylindrical silencer filled with a multilayer poroelastic material, employing the mode-matching method. To describe the numerical process of treating waves propagating within a poroelastic material and determine the modes in accordance with the boundary conditions necessary for analyzing the acoustic performance of the silencer, the Biot model and the Johnson–Champoux–Allard–Lafarge model were employed. The obtained modes were utilized to calculate the acoustic TL of silencers filled with single, double, and triple layers of poroelastic materials. In particular, the results obtained for the single layer were validated by comparing them with the results of a finite element analysis, and the results obtained for multiple layers with the same material were validated by comparing them with the equivalent single-layer results. Moreover, the results of the numerical calculations of the acoustic TLs of the silencer for three distinct types of poroelastic materials, including those with varying degrees of frame rigidity or softness, were compared, and the acoustic characteristics were analyzed in relation to the intrinsic properties of the materials and their arrangement. It is anticipated that the methodology presented in this paper will facilitate the design of silencers using poroelastic materials in accordance with the specific requirements of users or designers by allowing for a comprehensive consideration of the thickness of layers and the arrangement of materials.

Wasserstein distance in terms of the comonotonicity copula

The aim of this article is to write the p-Wasserstein metric W p with the p-norm, p ∈ [ 1 , ∞ ) , on R d in terms of copula. In particular for the case of one-dimensional distributions, we get that the copula employed to get the optimal coupling of the Wasserstein distances is the comotonicity copula. We obtain the equivalent result also for d-dimensional distributions under the sufficient and necessary condition that these have the same dependence structure of their one-dimensional marginals, i.e that the d-dimensional distributions share the same copula. Assuming p ≠ q , p,q ∈ [ 1 , ∞ ) and that the probability measures µ and ν are sharing the same copula, we also analyze the Wasserstein distance W p , q discussed in [Alfonsi and Jourdain. A remark on the optimal transport between two probability measures sharing the same copula. Statist. Probab. Lett. 84 (2014) 131–134.] and get an upper and lower bounds of W p , q in terms of W p , written in terms of comonotonicity copula. We show that as a consequence the lower and upper bound of W p , q can be written in terms of generalized inverse functions.

Wavelet-based resolvent analysis of non-stationary flows

This work introduces a formulation of resolvent analysis that uses wavelet transforms rather than Fourier transforms in time. Under this formulation, resolvent analysis may extend to turbulent flows with non-stationary mean states. The optimal resolvent modes are augmented with a temporal dimension and are able to encode the time-transient trajectories that are most amplified by the linearised Navier–Stokes equations. We first show that the wavelet- and Fourier-based resolvent analyses give equivalent results for statistically stationary flow by applying them to turbulent channel flow. We then use wavelet-based resolvent analysis to study the transient growth mechanism in the near-wall region of a turbulent channel flow by windowing the resolvent operator in time and frequency. The computed principal resolvent response mode, i.e. the velocity field optimally amplified by the linearised dynamics of the flow, exhibits characteristics of the Orr mechanism, which supports the claim that this mechanism is key to linear transient energy growth. We also apply this method to non-stationary parallel shear flows such as an oscillating boundary layer, and three-dimensional channel flow in which a sudden spanwise pressure gradient perturbs a fully developed turbulent channel flow. In both cases, wavelet-based resolvent analysis yields modes that are sensitive to the changing mean profile of the flow. For the oscillating boundary layer, wavelet-based resolvent analysis produces oscillating principal forcing and response modes that peak at times and wall-normal locations associated with high turbulent activity. For the turbulent channel flow under a sudden spanwise pressure gradient, the resolvent modes gradually realign themselves with the mean flow as the latter deviates. Wavelet-based resolvent analysis thus captures the changes in the transient linear growth mechanisms caused by a time-varying turbulent mean profile.

Decompression and reconstruction the spinal TB lesion of a single vertebra through thoracoscopy alone or combined with foraminal endoscopy

ObjectiveThis study aimed to compare the clinical efficacy of thoracoscopy combined with transforaminal endoscopy and thoracoscopy alone in the treatment of thoracic tuberculosis.MethodsPatients with thoracic tuberculosis who visited our hospital from February 2018 to October 2022 were retrospectively analyzed. The patients were divided into thoracoscopic combined transforaminal endoscopic surgery group (group A) and thoracoscopic surgery alone group (group B) according to the surgical methods. Surgery-related information, VAS score, ODI score, degree of spinal cord function improvement, fusion time, and progression of kyphotic deformity were compared.ResultsA total of 37 patients were included, 16 in group A and 21 in group B. Postoperative follow-up time was 10–48 months, with an average of 28.62 ± 10.53 months. All patients had significant improvement in chest and back pain and spinal cord function after the operation. There were statistical differences in operation time, intraoperative blood loss, incidence rate of complications, and JOA score at 1 week and 3 months after operation between the two groups (P<0.05). There was no significant difference in VAS, ODI score, kyphotic angle correction, kyphotic correction loss angle, postoperative drainage volume, and fusion time between the two groups (P>0.05). All patients had no recurrence of thoracic tuberculosis during follow-up.ConclusionThoracoscopy combined with transforaminal endoscopy produce equivalent long-term results with shorter operation time, less intraoperative blood loss, less complications and higher surgical safety comparing to thoracoscopy alone. And thoracoscopy combined with transforaminal endoscopy can fully decompress and facilitate the early recovery of spinal cord function.

Quantitative Equivalence and Performance Comparison of Particle and Field-Theoretic Simulations.

Particle and field-theoretic simulations are both commonly used methods to study the equilibrium properties of polymeric materials. Yet despite the formal equivalence of the two methods, no comprehensive comparisons of particle and field-theoretic simulations exist in the literature. In this work, we seek to fill this gap by performing a systematic and quantitative comparison of particle and field-theoretic simulations. In our comparison, we consider four representative polymeric systems: a homopolymer melt/solution, a diblock copolymer melt, a polyampholyte solution, and a polyelectrolyte gel. For each of these systems, we first demonstrate that particle and field-theoretic simulations are equivalent and yield exactly the same results for the pressure and the chemical potential. We next quantify the performance of each method across a range of different conditions including variations in chain length, system density, interaction strength, system size, and polymer volume fraction. The outcome of these calculations is a comprehensive look into the performance of each method and the systems and conditions when either particle or field-theoretic simulations are preferred. We find that field-theoretic simulations are equal to or faster than particle simulations for nearly all of the systems and conditions examined. In many situations, field-theoretic simulations are several orders of magnitude faster than particle simulations, especially if the polymer chains are long, the system density is high, and long-range Coulombic interactions are present. We also demonstrate that field-theoretic simulations are considerably faster at calculating the chemical potential and bypass the challenges associated with particle-based Widom insertion techniques. Taken together, our results provide quantitative evidence that field-theoretic simulations can reach and sample equilibrium considerably faster than particle simulations while simultaneously producing equivalent results.

Probability density functions for photon propagation in a binary (isotropic-Poisson) statistical mixture with unmatched positive and negative refractive indexes.

The exact homogenized probability density function, for a photon making a step of length s has been analytically derived for a binary (isotropic-Poisson) statistical mixture with unmatched refractive indexes. The companions, exact, homogenized probability density functions for a photon to change direction ("scatter"), with polar ϑ and azimuthal φ angles, and the homogenized albedo, have also been obtained analytically. These functions also apply to negative refractive indexes and can reduce the number of Monte Carlo simulations needed for photon propagation in complex binary (isotropic-Poisson) statistical mixtures from hundreds to just one, for an equivalent homogeneous medium. Note, that this is not an approximate approach, but a mathematically equivalent and exact result. Additionally, some tutorial examples of homogenized Monte Carlo simulations are also given.

Clinical and Structural Results Following Arthroscopic and Open Repair of Isolated Subscapularis Tears.

Objective: With advances in techniques, arthroscopic repair of isolated subscapularis tendon tears has become increasingly popular in recent years. The aim of this study was to analyze the clinical and structural results of arthroscopic repair versus the gold standard of open repair. It is a prospective cohort study with a control group; evidence level III. Methods: In a prospective study performed at two centers, 18 patients with an isolated subscapularis tear were treated with arthroscopic repair (ARG) and 16 patients with open repair (ORG) using a uniform single-row suture anchor repair technique in both groups. The subscapularis function was assessed using specific clinical tests (belly-press and lift-off tests), strength testing and shoulder function with the use of the Constant-Murley score (CMS). Standardized magnetic resonance imaging (MRI) was used to evaluate the postoperative subscapularis muscle-tendon status. Results: At a minimum follow-up of 48 months, the CMS increased from a mean of 54 points preoperatively to a mean of 86 points postoperatively in the ARG (p < 0.01) and from 50 points to 85 points postoperatively in the ORG (p < 0.01). Specific subscapularis tests (belly-press test and lift-off test) were significantly improved from the preoperative to the postoperative status in both repair groups (p < 0.05). Despite a subscapularis tendon healing rate of over 90% on MRI scans in both repair groups, the incomplete correction of specific muscle tests was a frequent postoperative finding. Conclusions: Arthroscopic repair of isolated subscapularis tears achieved equivalent clinical and structural results compared to the gold standard of open repair.

A Strong Gravitational Lens Is Worth a Thousand Dark Matter Halos: Inference on Small-scale Structure Using Sequential Methods

Strong gravitational lenses are a singular probe of the Universe’s small-scale structure—they are sensitive to the gravitational effects of low-mass (<1010 M ⊙) halos even without a luminous counterpart. Recent strong-lensing analyses of dark matter structure rely on simulation-based inference (SBI). Modern SBI methods, which leverage neural networks as density estimators, have shown promise in extracting the halo-population signal. However, it is unclear whether the constraints from these models are limited by the methodology or the data. In this study, we introduce an accelerator-optimized simulation pipeline that can generate lens images with realistic subhalo populations in milliseconds. Leveraging this simulator, we identify the main limitation of our fiducial SBI analysis: training set size. We then adopt a sequential neural posterior estimation (SNPE) approach, allowing us to refine the training distribution to align with the observed data. Using only one-fifth as many mock Hubble Space Telescope images, SNPE matches the constraints on the low-mass halo population produced by our best nonsequential model. Our experiments suggest that an over 3 order-of-magnitude increase in training set size and GPU hours would be required to achieve an equivalent result without sequential methods. While the full potential of the existing lens sample remains to be explored, the notable improvement in constraining power enabled by our sequential approach highlights that current constraints are limited primarily by methodology and not the data itself. Moreover, our results emphasize the need to treat training set generation and model optimization as interconnected stages of any cosmological analysis using SBI.

Transcatheter Aortic Valve Replacement Versus Surgical Aortic Valve Replacement in Bicuspid Aortic Valve Stenosis-We Need a Well-Designed Randomized Control Trial.

Bicuspid aortic stenosis is a common pathology, typically seen in patients a decade younger than those with tricuspid valves. Surgical aortic valve replacement has been the mainstay treatment for bicuspid disease, especially considering the prevalence of concomitant aortic aneurysmal pathology. Transcatheter aortic valve replacement has shown equivalent results in bicuspid compared to tricuspid pathology in highly selected patient populations in single-arm registries and observational studies. For older patients with favorable bicuspid pathology, TAVR is reasonable. However, as younger patients with longer life expectancy are now being treated with TAVR, what is "best" is a question only answered by a well-designed randomized controlled trial. Herein, we describe the current evidence for treating bicuspid aortic stenosis and provide a framework for future trials. Yet, the question of equipoise remains, and who will we enroll?

Feasibility and accuracy of pediatric core temperature measurement using an esophageal probe inserted through the gastric lumen of a second-generation supraglottic airway device: a prospective observational study.

Accurate core temperature measurement in children is crucial; however, measuring esophageal temperature (TE) using a supraglottic airway device (SAD) can be challenging. Second-generation SADs, which have a gastric channel, can measure TE, and reduce gastric air volume. This study aimed to compare TE, measured using a probe inserted through the SAD gastric channel, with tympanic membrane (TTM) and forehead (TZHF) temperatures, measured using a zero-heat-flux cutaneous thermometer, with rectal temperature (TR). Temperature was recorded at 10-min intervals from 10 min after probe insertion until completion of surgery. We performed an equivalence test to evaluate whether the TE, TTM, and TZHF were equivalent to TR, with a margin of 0.3°C. Additionally, intraclass correlation coefficients (ICC) were calculated to assess the reliability of TE and TR at each time point. We included 41 patients in the final analysis. In all patients, the esophageal probe was successfully inserted through the gastric channel of the SAD. When assessing agreement with TR as a reference, TE demonstrated equivalent results at all time points (P < 0.001 at 0, 10, 20, 30, and 40-min intervals and P = 0.018 at the 50-min interval), except at the completion of surgery (P = 0.697). TE also demonstrated good reliability with TR as a reference throughout the surgery (ICC > 0.75). In children with SAD insertion, TE can be accurately and feasibly measured through the SAD's gastric channel, making it suitable for routine application.

Using Bland-Altman plot-based harmonization algorithm to optimize the harmonization for immunoassays.

Harmonization has been recommended by theInternational Organization for Standard (ISO) to achieve equivalent results across invitro diagnostic measurement devices (IVD-MDs). We aim to evaluate the effectiveness of Bland-Altman plot-based harmonization algorithm (BA-BHA) created in this study and compare it with weighted Deming regression-based harmonization algorithm (WD-BHA) proposed in ISO 21151:2020. Eighty patient sera were used as the harmonization reference material (HRM) to develop IVD-MD-specific harmonization algorithms. Another panel of 40 patient sera was used to validate the effectiveness of harmonization algorithms. We compared regression slopes, intercepts, Bland-Altman plot layouts, percent differences, limits of agreement (LoAs), between-method coefficients of variation (CV) before and after harmonization. After harmonization by WD-BHA, acceptable slopes and intercepts between measured values and HRM targets were observed in weighted Deming regression, but not in Passing-Bablok analysis. Mean differences were-5.5 to 5.0 % and differences at specific levels were-33.9 to 23.9 %. LoAs were-64.6 to 74.6 %. Between-method CV was 22.9 % (±12.9 %). However, after harmonization by BA-BHA, both weighted Deming and Passing-Bablok regressions equations presented harmonized results. Mean differences were-0.3 to 0.2 % and differences at specific levels were-1.1 to 1.6 %. LoAs were-23.3 to 23.2 %. Between-method CV was 8.4 % (±4.0 %). The data points were evenly distributed at both sides of the mean in Bland-Altman plots. The inequivalence of test results between different methods can be improved but unacceptable analytical differences at specific levels may be hidden in terms of an acceptable slope and intercept on WD-BHA. The new protocol BA-BHA may be a viable alternative to optimize the harmonization for immunoassays.

Development of a novel computational technique to create DNA and cell geometrical models for Geant4-DNA

BackgroundThis study aimed to develop a novel human cell geometry for the Geant4-DNA simulation toolkit that explicitly incorporates all 23 chromosome pairs of the human cell. This approach contrasts with the existing, default human cell, geometrical model, which utilizes a continuous Hilbert curve. MethodsA Python-based tool named “complexDNA” was developed to facilitate the design of both simple and complex DNA geometries. This tool was employed to construct a human cell geometry with individual pairs of chromosomes. Subsequently, the performance of this chromosomal model was compared to the standard human cell model provided in the “molecularDNA” Geant4-DNA example. ResultsSimulations using the new chromosomal model revealed minimal discrepancies in DNA damage yield and fragment size distribution compared to the default human cell model. Notably, the chromosomal model demonstrated significant computational efficiency, requiring approximately three times less simulation time to achieve equivalent results. ConclusionsThis work highlights the importance of incorporating chromosomal structure into human cell models for radiation biology research. The “complexDNA” tool offers a valuable resource for creating intricate DNA structures for future studies. Further refinements, such as implementing smaller voxels for euchromatin regions, are proposed to enhance the model’s accuracy.

An efficient improved singular spectrum analysis for processing GNSS position time series with missing data

SUMMARY The improved SSA (ISSA) method is widely recognized for directly extracting signals from gappy time-series without requiring prior interpolation. However, it is rather time consuming, particularly for long time-series with large window sizes, such as Global Navigation Satellite System (GNSS) position time-series. This study proposes an efficient ISSA method that yields equivalent results to the ISSA method while significantly reducing computation time. Both methods aim to minimize the quadratic norm of principal components, while our method has fewer unknown parameters in the principal component computation than those of the ISSA method. We evaluate the performance of the proposed method using real GNSS position time-series from 27 permanent stations located in mainland China. Results show that the proposed method can effectively reduce computation time than the ISSA method and the improvement depends on the chosen window size, the time-series length and the percentage of missing data. This efficient approach can be naturally extended to principal component analysis (PCA) and multichannel SSA (MSSA) for processing multiple incomplete time-series, improving computational efficiencies compared to the modified PCA and the improved MSSA while maintaining unchanged results. We also compare the ISSA method with the modified SSA (SSAM) and the iterative SSA methods using both real and synthetic time-series data. Results indicate that the ISSA method outperforms the SSAM method, and when conducted iteratively, also surpasses the iterative SSA method.

FIELDimagePy: A tool to estimate zonal statistics from an image, bounded by one or multiple polygons

AbstractVegetation indices have become an indispensable tool in remote sensing‐based agricultural research. A recent area of advancement in agricultural remote sensing research is in high‐throughput phenotyping, often conducted on a plot by plot basis. FIELDimageR is a tool used extensively in high‐throughput phenotyping that estimates zonal statistics of vegetation indices per plot. However, being written in R language, FIELDimageR requires high computing time. As a high‐resolution image over a large area means a large number of pixels, FIELDimageR is incapable of using high‐resolution orthomosaicked images without reducing image resolution by aggregating digital numbers of several pixels and treating them as one pixel. This research tool implements FIELDimageR in the Python language as FIELDimagePy. FIELDimagePy follows similar workflows as FIELDimageR and generates equivalent results for zonal statistics of vegetation indices per plot. FIELDimagePy is significantly and substantially faster than FIELDimageR. Computing time by FIELDimagePy are three to four times lower than computing times by FIELDimageR, even when using raw images with 16 times denser pixels. Moreover, FIELDimagePy is useful beyond plot by plot research in agriculture and capable of estimating zonal statistics of any raster bounded by any polygons. With slight modifications, FIELDimagePy can be useful for other disciplines of science, such as geophysics, geography, economics, medical sciences, among others. FIELDimagePy can be accessed from the GitHub repository: https://github.com/SumantraChatterjee/FIELDimagePy.

Deep belief network with fuzzy parameters and its membership function sensitivity analysis

Over the last few years, deep belief networks (DBNs) have been extensively utilized for efficient and reliable performance in several complex systems. One critical factor contributing to the enhanced learning of the DBN layers is the handling of network parameters, such as weights and biases. The efficient training of these parameters significantly influences the overall enhanced performance of the DBN. However, the initialization of these parameters is often random, and the data samples are normally corrupted by unwanted noise. This causes the uncertainty to arise among weights and biases of the DBNs, which ultimately hinders the performance of the network. To address this challenge, we propose a novel DBN model with weights and biases represented using fuzzy sets. The approach systematically handles inherent uncertainties in parameters resulting in a more robust and reliable training process. We show the working of the proposed algorithm considering four widely used benchmark datasets such as: MNSIT, n-MNIST (MNIST with additive white Gaussian noise (AWGN) and MNIST with motion blur) and CIFAR-10. The experimental results show superiority of the proposed approach as compared to classical DBN in terms of robustness and enhanced performance. Moreover, it has the capability to produce equivalent results with a smaller number of nodes in the hidden layer; thus, reducing the computational complexity of the network architecture. Additionally, we also study the sensitivity analysis for stability and consistency by considering different membership functions to model the uncertain weights and biases. Further, we establish the statistical significance of the obtained results by conducting both one-way and Kruskal-Wallis analyses of variance tests.

Design and analysis of low-profile quad element wide band MIMO antenna with efficient isolation for C and X-band applications

ABSTRACT A low-profile, quad-element multiple-input/multiple-output (MIMO) antenna of 0.69 λ 0 λ 0 is presented in this study. The proposed design consists of a stub and slot-loaded partial ground plane with a quad rectangular-shaped radiator on top. The four elements are placed orthogonally to one another to reduce mutual coupling and envelope correlation coefficient (ECC). The maximum isolation of the proposed MIMO antenna is 61.5 dB at 9.94 GHz frequency. It achieved impedance bandwidth 5.56 GHz, ranging from 5.74–11.30 GHz. The peak gain of the proposed MIMO antenna is 6.18 dB at 7.3 GHz, with a maximum efficiency of 89.21% at 7.1 GHz. The minimum ECC between ports 1 and 2 over the operating band are observed as 0.0001. To achieve the best outcome, a parametric analysis of the proposed antenna is also performed. Various diversity characteristic metrics, including diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC), channel capacity loss (CCL), and ergodic channel capacity (CC), are thoroughly analysed to determine how well the MIMO antenna performs in terms of diversity. Over the operating band, the measured values provide good agreement with respect to simulated and equivalent circuit model results, indicating a strong candidacy for operation in the investigated bands. The proposed MIMO antenna have the potential for C and X band applications such as WLAN, radio astronomy, satellite communication, and automotive radar.