bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study of Turbulent Wake Flow Around Trapezoidal Cylinders With Varying Streamwise Aspect Ratios
Authors: Kang Jinhao , Tachie Mark F.
Published: March 2023

The effects of streamwise aspect ratio (AR) on the asymmetric wake flow over and behind right-angled trapezoidal cylinders with AR (= upper cylinder length to height ratio) = 1, 2, 3, 4, and 5 were investigated using particle image velocimetry. The Reynolds number based on the freestream velocity and cylinder height was 14700. The flow characteristics are examined in terms of the mean velocity flow, Reynolds stresses, probability density function (PDF), and two-point correlations. The results show that the primary vortex in the AR1 and AR2 trapezoidal cases extends into the wake region but is confined to the surface of the longer cases and two asymmetrical wake vortexes are only observed in the longer cases. Dual peaks of elevated streamwise Reynolds stresses are observed in the wake region, regardless of the aspect ratios. The magnitudes of the Reynolds stresses and turbulent kinetic energy are higher in the shorter cases (AR1, AR2, and AR3 cases) compared to the longer cases. The PDF distributions show a bimodal asymmetrical shape in the shorter cases but a nearly Gaussian distribution in the AR5 case. Two-point autocorrelations of the streamwise and vertical velocity fluctuations revealed that the spatial coherency of the turbulent structures is highly sensitive to the streamwise aspect ratio and reference locations. Systematic comparison between the present asymmetric results and symmetric wakes generated by rectangular cylinders with similar aspect ratios and Reynolds number shows significant differences between the asymmetric and symmetric wakes, especially at smaller aspect ratios.
Experimental Study on Gas–Liquid Performance and Prediction of Shaft Power and Efficiency by Dimensionless Coefficients in a Multistage Electrical Submersible Pump
Authors: Chang Liang , Xu Qiang , Yang Chenyu , Su Xiaobin , Dai Xiaoyu , Guo Liejin
Published: March 2023

Electrical submersible pumps (ESPs) widely used in oil-gas artificial lift consume a lot of electric energy in long-term operation. This paper mainly focuses on the gas–liquid performance and predicting shaft power and efficiency of a 25-stage ESP. First, the calculation methods of two-phase hydraulic parameters and corresponding dimensionless hydraulic coefficients based on isothermal compression are proposed. Ignoring the gas compressibility will result in large errors in calculating two-phase hydraulic parameters. Then, the effects of liquid flowrate, inlet gas volume fraction, and rotational speed on head, shaft power, and efficiency are analyzed. The severe two-phase head degradation disappears in downstream stages of the ESP because of the decreasing interstage gas volume fraction. Similar to the head, the shaft power and efficiency decrease slowly at first, then rapidly, and finally slowly with the increase of inlet gas volume fraction. Finally, correlations are proposed for predicting the shaft power and efficiency by the dimensionless head and flow coefficients. There is a power function relation between two-phase head coefficient and efficiency. Thus, through the pump head which can be easily acquired by differential pressure signals in pipeline, prediction correlations for shaft power and efficiency are established with the relative errors lower than 10%. The prediction method based on two-phase dimensionless coefficients can also be referenced to ESPs with different types.
Flow Control Around a Cylinder With a Perforated Cylinder
Authors: Canpolat Cetin , Hamzah Hudhaifa , Sahin Besir
Published: March 2023

In this work, periodic vortex shedding at both sides of a circular cylinder is aimed to be suppressed using a concentrically located perforated cylinder under laminar flow conditions at Re = 200. A code is developed in comsolmultiphysics, 5.3a, and validated using the outcomes of ansysfluent, and previous studies in the open literature, which exhibit a good agreement. In this study, the porosity, β is varied within 0.5 ≤ β ≤ 0.9, and the gap ratio, D/d is varied within 1.5 ≤ D/d ≤ 3.5. The results of the present numerical investigation are evaluated using instantaneous and time-averaged vorticity, streamwise, and transverse components of the velocity and pressure. The drag, CD and lift, CL coefficients are calculated. The Strouhal number, St from the pointwise spectral analysis of the streamwise velocity component is plotted for various cases. It is observed that porosity, β has a dominant effect rather than the gap ratio, D/d on the flow past a solid cylinder. The low-velocity and low-pressure regions are getting large in the transverse direction as the porosity, β increases. The separated layers from solid and perforated cylinders merge for low gap ratios, D/d. However, individual movement of these layers is evident for larger gap ratios, D/d with low porosity, β values. A perfect suppression of the periodicity of vortex shedding is obtained for the cases of D/d = 3.5 with β = 0.5, 0.6, and D/d = 3 with β = 0.5.
Unsteady Simulation and Analysis of Energy Loss Mechanism of a Vertical Volute Pump Under Stall Conditions
Authors: Zhang Chenying , Pei Ji , Wang Wenjie , Yuan Shouqi , Gan Xingcheng , Huang Congbing , Chen Jia
Published: March 2023

This study comprehensively investigates the flow features and energy loss mechanisms under stall conditions based on computational fluid dynamics (CFD) and hydraulic loss visualization techniques. The three-dimensional unsteady Reynolds-averaged Navier– Stokes (URANS) equations were solved using the shear stress transport (SST) k–ω turbulence model. Furthermore, the entire flow domain of the vertical volute pump was considered to capture the boundary flow behavior accurately. The results illustrate that the critical stall condition occurs at 0.7Qd, where the H–Q curve exhibits a positive slope, and the deep stall condition occurs at 0.65Qd. The growth rate of energy loss from critical stall to deep stall is 182.2%. In the stall condition, a secondary vortex appears at the impeller inlet. A high energy loss occurs at the suction side and trailing edge in the impeller caused by the reduction in the effective inflow area. The energy loss in the blade suction side guide vane is primarily due to the friction loss under the critical stall condition. By contrast, under the deep stall condition, the energy loss in the outlet of the guide vane is mainly the impact loss from the volute of the rear gunner. The impact effect can result in high energy losses near the volute tongue. The entropy production analysis demonstrates that the hydraulic losses in the diffuser are literately greater than that in the impeller and inlet pipe. Hence, optimization of such components can be taken into consideration in future works for performance improvement.
Experimental Study of The Pressure-Time Method With Potential Application for Low-Head Hydropower
Authors: Neyestanaki Mehrdad Kalantar , Dunca Georgiana , Jonsson Pontus , Cervantes Michel J.
Published: March 2023

The pressure-time method allows measuring the flowrate in hydraulic turbines, according to IEC 60041 standard. According to this standard, the applicability of the pressure-time method is limited to a straight pipe with a constant cross section with specific limits for length and velocity. However, low-head hydropower plants usually have an intake with a variable cross section and short length making this method difficult to be applied. In this paper, a test rig has been developed to extend the method's applicability. The test rig is designed for developing flows condition and small measurement lengths for pipes with constant and variable cross section, which could be similar to low-head turbine conditions. For pipe with constant cross section, three measuring lengths of 0.5, 1, and 1.5 m can be obtained on this test rig to study the pressure-time method. For pipe with variable cross section, the method is applied across a concentric reducer with a length of 255 mm, i.e., a 9.46 deg reducing angle. Different flow assumptions for estimation of the head loss and dynamic pressure variation are considered to compare the accuracy of discharge measurement. The results showed that the quasi-steady assumption for friction factor and kinetic energy, along with friction factor correction, increases the method accuracy up to 0.4% compared with the current standard recommendations. Moreover, the Monte Carlo method (MCM) is applied to estimate the transient measurement uncertainty and compared with the Taylor series method (TSM).
Characterization of Two-Phase Wakes in an Upward Adiabatic Liquid-Gas Flow Around a Cylinder
Authors: Kim Dohwan , Rau Matthew J.
Published: March 2023

Two-phase wakes generated from a cylinder in a crossflow were experimentally studied. A water–air mixture traveled through a vertical water channel with a rectangular cross section, in which a cylinder was installed horizontally. Liquid Reynolds numbers, based on a cylinder diameter of 9.5 mm, were varied from Re = 100 to 3,000; the air superficial velocities were varied from jg = 0.06 m/s to 0.60 m/s; and mean bubble diameters were varied from 0.48 mm to 3.5 mm. Void fraction distribution in the wake of the cylinder was determined from high-speed visualizations, where a correlation was applied to the shadow fraction measurements to account for overlapping bubble images. It divided the wakes into a liquid-phase region with a low void fraction relative to its freestream condition (α/α∞<1/2) and a bubble-trapping region with a relatively high void fraction (α/α∞>2). The liquid-phase region occurred in all flow conditions, but its length decreased with increasing Reynolds number. In contrast, the bubble-trapping region occurred only at relatively high Reynolds numbers depending on the bubble size and air superficial velocity. Transitional bubble-trapping behavior was identified at Re = 1,200 for the 3.5 mm bubbles, where bubble trapping only occurred at low air superficial velocities. Once the bubble-trapping region developed sufficiently, the location of the maximum void fraction was consistently located at y/D = 1.3–1.5 downstream from the center of the cylinder.
Elastic–Plastic Properties of Mesoscale Electrodeposited LIGA Nickel Alloy Films: Analysis of Measurement Uncertainties
Authors: Liew Li-Anne , Read David T. , Martin May L. , Bradley Peter E. , Geaney John T.
Published: March 2023

It is well documented that the microstructure and properties of electrodeposited films, such as lithographie, galvanoformung, abformung (LIGA) Ni and its alloys, are highly sensitive to processing conditions hence the literature shows large discrepancies in mechanical properties, even for similar alloys. Given this expected material variability as well as the experimental challenges with small-scale mechanical testing, measurement uncertainties are needed for property values to be applied appropriately, and yet are uncommon in micro- and mesoscale tensile testing studies. In a separate paper, we reported the elastic–plastic properties of 200 μm-thick freestanding films of LIGA-fabricated nanocrystalline Ni-10%Fe and microcrystalline Ni-10%Co, with specimen gauge widths ranging from 75 μm to 700 μm, and tensile tested at strain rates 0.001 s−1 and 1 s−1. The loads were applied by commercial miniature and benchtop load frames, and strain was measured by digital image correlation. In this paper, we examine the measurement uncertainties in the ultimate tensile strength, apparent Young's modulus, 0.2% offset yield strength, and strain hardening parameters, and compare them to the standard deviations. For several of these properties, the standard deviation cannot be interpreted as the statistical scatter because the measurement uncertainty was larger. Microplasticity affects the measurement of the Young's modulus, thus we recommended measuring the modulus after specimens have been cyclically loaded. These measurement uncertainty issues might be relevant to similar works on small-scale tensile testing and might help the reader to interpret the discrepancies in literature values of mechanical properties for LIGA and electrodeposited films.
Perceptual simultaneity range for two dichotically presented pure tones with frequency separation below 0.5 Bark
Authors: Okazaki Satoshi , Ichikawa Makoto , Tsuzaki Minoru
Published: March 2023

The perceptual simultaneity range for two diotically presented tones increases with decreasing frequency separation of the two tones from approximately 0.5 Bark. As the present study of two frequency regions shows, this effect is not observed when the two tones are not presented to the same ear, i.e., presented dichotically. Since the increase in simultaneity is only observed when the tones are presented to the same ear, it is possible that it reflects the time-frequency uncertainty within a cochlear filter.
Mental Fatigue: The Cost of Cognitive Loading on Weight Lifting, Resistance Training, and Cycling Performance
Authors: Staiano Walter , Bonet Lluis Raimon Salazar , Romagnoli Marco , Ring Christopher
Published: March 2023

Purpose: Mental fatigue (MF) can impair physical performance in sport. We tested the hypothesis that cognitive load alone, and intermixed with standard resistance training, would induce MF, increase rating of perceived exertion (RPE), alter perception of weight lifting and training, and impair cycling time-trial performance. Methods: This 2-part study employed a within-participant design. In part 1, after establishing leg-extension 1-repetition maximum (1RM), 16 participants lifted and briefly held weights at 20%, 40%, 60%, and 80% of 1RM. RPE and electromyography (EMG) were measured for each lift. During the testing sessions, participants completed cognitive tasks (MF condition) or watched neutral videos (control condition) for 90 minutes before lifting the weights. In part 2, they completed submaximal resistance training comprising 6 weight training exercises followed by a 20-minute cycling time trial. In the MF condition, they completed cognitive tasks before and between weight training exercises. In the control condition, they watched neutral videos. Mood (Brunel Mood Scale), workload (National Aeronautics and Space Administration Task Load Index), MF-visual analogue scale (MF-VAS), RPE, psychomotor vigilance, distance cycled, power output, heart rate, and blood lactate were measured. Results: In part 1, the cognitive task increased lift-induced RPE (P = .011), increased MF-VAS (P = .002), and altered mood (P < .001) compared with control. EMG did not differ between conditions. In part 2, the cognitive tasks increased RPE (P < .001), MF-VAS (P < .001), and mental workload (P < .001), but reduced cycling time-trial power (P = .032) and distance (P = .023) compared with control. Heart rate and blood lactate did not differ between conditions. Conclusion: A state of MF induced by cognitive load, alone or intermixed with physical load, increased RPE during weight lifting and training and impaired subsequent cycling performance.
In Vitro
Susceptibility and Resistance of Mycoplasma genitalium to Nitroimidazoles
Authors: Wood Gwendolyn E. , Kim Caroline M. , Aguila Laarni Kendra T. , Cichewicz Robert H.
Published: March 2023

Mycoplasma genitalium
is a sexually transmitted reproductive tract pathogen of men and women.
M. genitalium
infections are increasingly difficult to treat due to poor efficacy of doxycycline and acquired resistance to azithromycin and moxifloxacin. A recent clinical trial suggested that metronidazole may improve cure rates for women with pelvic inflammatory disease and reduced the detection of
M. genitalium
when included with standard doxycycline plus ceftriaxone treatment.
Identification of a protein expression signature distinguishing early from organising diffuse alveolar damage in COVID-19 patients
Authors: Ashwin Helen , Milross Luke , Wilson Julie , Majo Joaquim , Hang Lee Jimmy Tsz , Calder Grant , Hunter Bethany , James Sally , Lagos Dimitris , Signoret Nathalie , Filby Andrew , Bayraktar Omer Ali , Fisher Andrew J , Kaye Paul M
Published: March 2023

Diffuse alveolar damage (DAD) is the histological expression of acute respiratory distress syndrome and characterises lung pathology due to infection with SARS-CoV-2, and other respiratory pathogens of clinical significance. DAD reflects a time-dependent immunopathological process, progressing from an early/exudative stage through to an organising/fibrotic stage, yet within an individual these different stages of DAD may coexist. Understanding the progression of DAD is central to the development of new therapeutics to limit progressive lung damage. Here, we applied highly multiplexed spatial protein profiling to autopsy lung tissues derived from 27 patients who died from COVID-19 and identified a protein signature (ARG1, CD127, GZMB, IDO1, Ki67, phospho-PRAS40 (T246) and VISTA) that distinguishes early DAD from late DAD with good predictive accuracy. These proteins warrant further investigation as potential regulators of DAD progression.
Comprehensive laboratory diagnosis of Fanconi anaemia: comparison of cellular and molecular analysis
Authors: Joshi Gaurav , Arthur Nancy Beryl Janet , Geetha Thenral S , Datari Phaneendra Venkateswara Rao , Modak Kirti , Roy Debanjan , Chaudhury Anurag Dutta , Sundaraganesan Prasanth , Priyanka Sweety , NA Fouzia , Ramprasad Vedam , Abraham Aby , Srivastava Vivi M , Srivastava Alok , Kulkarni Uday Prakash , George Biju , Velayudhan Shaji R
Published: March 2023

Background

Fanconi anaemia (FA) is a rare inherited bone marrow failure disease caused by germline pathogenic variants in any of the 22 genes involved in the FA-DNA interstrand crosslink (ICL) repair pathway. Accurate laboratory investigations are required for FA diagnosis for the clinical management of the patients. We performed chromosome breakage analysis (CBA), FANCD2 ubiquitination (FANCD2-Ub) analysis and exome sequencing of 142 Indian patients with FA and evaluated the efficiencies of these methods in FA diagnosis.

Methods

We performed CBA and FANCD2-Ub analysis in the blood cells and fibroblasts of patients with FA. Exome sequencing with improved bioinformatics to detect the single number variants and CNV was carried out for all the patients. Functional validation of the variants with unknown significance was done by lentiviral complementation assay.

Results

Our study showed that FANCD2-Ub analysis and CBA on peripheral blood cells could diagnose 97% and 91.5% of FA cases, respectively. Exome sequencing identified the FA genotypes consisting of 45 novel variants in 95.7% of the patients with FA.FANCA(60.2%),FANCL(19.8%) andFANCG(11.7%) were the most frequently mutated genes in the Indian population. AFANCLfounder mutation c.1092G>A; p.K364=was identified at a very high frequency (~19%) in our patients.

Conclusion

We performed a comprehensive analysis of the cellular and molecular tests for the accurate diagnosis of FA. A new algorithm for rapid and cost-effective molecular diagnosis for~90% of FA cases has been established.
Patient-centered results from a multicenter study of continuous peripheral nerve blocks and postamputation phantom and residual limb pain: secondary outcomes from a randomized, clinical trial
Authors: Ilfeld Brian M , Khatibi Bahareh , Maheshwari Kamal , Madison Sarah , Ali Sakr Esa Wael , Mariano Edward R , Kent Michael , Hanling Steven , Sessler Daniel I , Eisenach James C , Cohen Steven P , Mascha Edward , Li Shuyi , Turan Alparslan
Published: March 2023

Introduction

We previously reported that a 6-day continuous peripheral nerve block reduces established postamputation phantom pain. To provide patients and providers with the information to best inform treatment decisions, here we reanalyze the data and present the results in a more patient-centered format. We also provide information on patient-defined clinically relevant benefits to facilitate evaluation of available studies and guide future trial design.

Methods

The original trial enrolled participants with a limb amputation and phantom pain who were randomized to receive a 6-day continuous peripheral nerve block(s) of either ropivacaine (n=71) or saline (n=73) in a double-masked fashion. Here we calculate the percentage of each treatment group that experienced a clinically relevant improvement as defined by previous studies as well as present what the participants of our study defined as small, medium, and large analgesic improvements using the 7-point ordinal Patient Global Impression of Change scale.

Results

Among patients who were given a 6-day ropivacaine infusion, 57% experienced at least a 2-point improvement on the 11-point numeric rating scale in their average and worst phantom pain 4 weeks postbaseline as compared with 26% (p<0.001) for average and 25% (p<0.001) for worst pain in patients given a placebo infusion. At 4 weeks, the percentage of participants rating their pain as improved was 53% for the active vs 30% for the placebo groups (95% CI 1.7 (1.1, 2.7), p=0.008). For all patients combined, the median (IQR) phantom pain Numeric Rating Scale improvements at 4 weeks considered small, medium, and large were 2 (0–2), 3 (2–5), and 5 (3–7), respectively. The median improvements in the Brief Pain Inventory interference subscale (0–70) associated with small, medium, and large analgesic changes were 8 (1–18), 22 (14–31), and 39 (26–47).

Conclusions

Among patients with postamputation phantom pain, a continuous peripheral nerve block more than doubles the chance of a clinically relevant improvement in pain intensity. Amputees with phantom and/or residual limb pain rate analgesic improvements as clinically relevant similarly to other chronic pain etiologies, although their smallest relevant improvement in the Brief Pain Inventory was significantly larger than previously published values.

Trial registration number

NCT01824082.
Heavy crown thinning in redwood/Douglas-fir gave superior forest restoration outcomes after 10 years
Authors: Dagley Christa M. , Fisher Judson , Teraoka Jason , Powell Scott , Berrill John-Pascal
Published: March 2023

Forest restoration thinning has the potential to enhance the structural complexity and accelerate the development of large trees important to wildlife, aesthetics, and wildfire resistance. These are key objectives for the restoration of even-aged secondary forests within Redwood National Park in Humboldt County, CA, USA. We evaluated the tree growth and stand structure 10 years after two thinning methods were applied at two intensities in a 40-year-old mixed redwood ( Sequoia sempervirens (Lamb. ex D. Don) Endl.)/Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. menziesii) stand. Heavy thinning enhanced the diameter growth of redwood and Douglas-fir trees more than light thinning. Crown thinning generally enhanced the structural diversity more than low thinning, and structural diversity increased progressively over the 10 years following thinning. Understory plant richness fluctuated between measurement years. Heavy thinning enhanced the understory shrub cover. The fastest-growing trees in heavily thinned stands were much more likely to sustain bear damage, especially redwood trees. Overall, different thinning methods and intensities induced a different suite of outcomes, yet none restored redwood dominance, but all treatments enhanced some other ecosystem values important for old-growth restoration such as large overstory trees, understory plant and shrubs, and elements of structural complexity, including tree-size variability, snags, down logs, and trees exhibiting stem or top damage.
Effects of splitter geometry as a passive control method on sound pressure level, a mathematical modeling
Authors: Bagherzadeh Amir , Abbasi Parizad Forough
Published: March 2023

This study investigates the aeroacoustics of flow around a square cylinder using an in-house OpenFoam solver with Ffowcs Williams’ Hawking methodology and the [Formula: see text] SST turbulence model. First, the numerical results were validated against experimental data. Then, the effects of a 1[Formula: see text]mm thick splitter with different lengths, 2.5 ([Formula: see text]), 5 ([Formula: see text]), 7.5 ([Formula: see text]) and 10 ([Formula: see text]), were studied as a passive control method. The findings indicate that the splitter suppresses the vortex shedding, a dipole source of aeroacoustic emission, resulting in a reduction of the noise level by up to 7% for [Formula: see text] for [Formula: see text] for [Formula: see text] and 17.5% for [Formula: see text].
W-boson mass anomaly and vacuum structure in vector dark matter model with a singlet scalar mediator
Authors: Ayazi Seyed Yaser , Hosseini Mojtaba
Published: March 2023

Motivated by the deviation of the [Formula: see text]-boson mass reported by the CDF collaboration, we study an extension of the Standard Model (SM) including a vector dark matter (VDM) candidate and a scalar mediator. In the model, the one-loop corrections induced by the new scalar shift the [Formula: see text]-boson mass. We identify the parameter space of the model consistent with dark matter (DM) relic abundance, [Formula: see text]-mass boson anomaly, invisible Higgs decay at LHC, and direct detection of DM. It is shown that the [Formula: see text]-mass anomaly can be explained for the large part of parameter space of VDM mass and scalar mediator mass between 100[Formula: see text]GeV and 124[Formula: see text]GeV by the model. We also investigate the renormalization group equations (RGEs) at one-loop order for the model. We show that the contribution of new scalar mediator to RGE guarantees positivity and vacuum stability of SM Higgs up to Planck scale.
Evolution of gravitational radiation from black hole under the influence of Einstein–Gauss–Bonnet gravity
Authors: Babar Rimsha , Akhtar Z. , Karamat Anosha , Asgher Muhammad , Ali Riasat
Published: March 2023

In our work, we compute the 4-dimensional Einstein–Gauss–Bonnet gravity black hole solution by applying the Newman–Janis approach and also examine the Hawking temperature. The generalized uncertainty principle (GUP) is applied to compute the Lagrangian field equation and by using the semi-classical phenomenon, we analyze the modified Hawking temperature. By taking into account the graphical analysis, we check the stable conditions of the black hole with the influence of rotation parameter, charged parameter and quantum gravity parameter. Furthermore, we compute the logarithmic entropy corrections in the background of corrected temperature and standard entropy for corresponding black hole. We study the behavior of different thermodynamics quantities like Helmholtz free energy, internal energy, Gibbs free energy and heat capacity under these fluctuations. In our analysis, we note that these corrections enhance the stability of this system, so, under the effects of these corrections, the considered geometry becomes more stable.
Edge states and SUSY in (2+1)-dimensional Maxwell Chern–Simons theory
Authors: Acharyya Nirmalendu , Sinha Akash
Published: March 2023

In a [Formula: see text]-dimensional Maxwell–Chern–Simons theory coupled with a fermion and a scalar, which has [Formula: see text] SUSY in the absence of the boundary, supersymmetry is broken on the insertion of a spatial boundary. We show that only a subset of the boundary conditions allowed by the self-adjointness of the Hamiltonian can preserve partial ([Formula: see text]) supersymmetry, while for the remaining boundary conditions SUSY is completely broken. In the latter case, we demonstrate two distinct SUSY-breaking mechanisms. In one scenario, the SUSY-breaking boundary conditions are not consistent with the supersymmetry transformations. In another scenario, despite the boundary conditions being consistent with the SUSY transformations, unpaired fermionic edge states in the domain of the Hamiltonian leads to the breaking of the supersymmetry.
Recent Progress on Calibration Methods of Timing Skew in Time-Interleaved ADCS
Authors: Yang Huijing , Zhang Ruidong , Ren Mingyuan
Published: March 2023

Time interleaving has become a very common choice for increasing ADC speed. However, it is accompanied by defects such as offset, gain and time offset between the individual sub-ADCs, which can seriously degrade the performance of the overall ADC. For the elimination of gain and offset errors, the solution is relatively simple, and the calibration of the time offset is still in the exploratory stage. This paper systematically reviews several current mainstream time-interleaved ADC timing offset correction methods. At the same time, the characteristics and development trend of calibration methods are summarized.
A Comprehensive Study of Different Techniques for Voltage References
Authors: Duggal Komal , Pandey Rishikesh , Niranjan Vandana
Published: March 2023

In the analog and mixed-signal integrated circuits, voltage references that are independent of various factors such as temperature drift, noise, supply voltage, etc., and efficient in terms of power as well as area, are highly in demand to improve the efficiency of the overall circuits. Voltage references are one of those circuits that have applications in both high-power systems and low-power system-on-chip (SoC) designs for wireless connectivity like the internet of the things (IoT) or the internet of the medical things (IoMT). They are responsible for providing a stable bias or reference voltage. Thus, voltage reference influences directly or indirectly the performance of these systems. A comparative study between the techniques used in bandgap voltage references and CMOS voltage references, in terms of performance parameters such as line sensitivity, output noise, PSRR, temperature coefficient, etc., is presented in this paper so that we can choose the voltage references as per the applications and environment.
NUMERICAL SOLUTIONS OF NONLINEAR DELAY INTEGRO-DIFFERENTIAL EQUATIONS USING HAAR WAVELET COLLOCATION METHOD
Authors: HADI FAZLI , AMIN ROHUL , KHAN ILYAS , ALZAHRANI J. , NISAR K. S. , AL-JOHANI AMNAH S. , ELDIN ELSAYED TAG
Published: March 2023

In this paper, Haar wavelet collocation method (HWCM) for nonlinear delay Volterra, delay Fredholm and delay Volterra–Fredholm Integro-Differential Equations (IDEs) are studied numerically using HWCM. This method is very useful for solving nonlinear IDEs. The technique (HWCM) reduced the given equations into a system of nonlinear algebraic equations. The nonlinear system is then solved by Broydens technique. Some numerical examples are taken from literature for the validation purpose, computational efficiency and convergence of the proposed method. The approximate solution is compared with the exact solution and the maximum absolute and mean square root errors are presented for each example in tables. The comparison between exact and approximate solution is shown in figures for each example. The results are compared with existing methods from the literature. The results exhibit that the HWCM is simple, precise and efficient.
Improved Operator-Splitting Method for Dynamic Real-Time Substructure Testing of Multiple-Degree-of-Freedom Structure
Authors: Xu Guoshan , Zheng Lichang , Fu Jiali , Zheng Zhenyun
Published: March 2023

The operator-splitting (OS) method for real-time substructure testing (RTST) provides explicit and unconditionally stable solutions for structures with softening type stiffness and damping has been widely used for precisely disclosing the seismic performance of structures with velocity-dependent specimens. However, the OS method for RTST provides only explicit target displacement and velocity but not an explicit target acceleration, so that it is essentially an implicit method for Dynamic real-time substructure testing (DRTST) with dynamic system specimens. For precisely disclosing the seismic performance of multiple-degree-of-freedom structures with dynamic system specimens, one improved OS method is proposed for DRTST in this paper. The methodology and stability of the proposed OS method are investigated, and the effectiveness of the proposed OS method is validated by numerical simulations and experimental tests. By using the predictor displacement, velocity, and acceleration approximations, the OS method is an explicit algorithm for DRTST. The stability analysis shows that the proposed OS method is conditionally stable for DRTST, and its stability limit decreases with the increase of the mass ratio and the stiffness ratio, while it increases first and then decreases with the increase of the damping ratio. The numerical and experimental results confirm the stability and accuracy of the OS method. The OS method for DRTST provides a practical and precise investigation strategy for structures with dynamic system specimens and may have broad application prospects in civil engineering.
Fabrication and Characterization of p-Sb2O3:CuO/n-Si Solar Cell Via Thermal Evaporation Technique
Authors: Attia Ali A. , Hashim Fouad Shakir , Haneen Abass Khalid
Published: March 2023

Antimonous oxide (Sb2O3) has intriguing physical and chemical features that make it useful in various device applications, including solar cells. Pure and CuO-doped Sb2O3 nanofilms were prepared on glass and silicon substrates etched by laser using a thermal evaporation process in a vacuum, with doping ratios (0.02 wt.%, 0.04 wt.% and 0.06 wt.%) of CuO with a thickness of about 40 nm. The deposited nanofilms have no distinguishing peaks in X-ray diffraction analysis. Broadening of X-ray peaks shows the absence of long-range symmetry (either translational, rotational or conformational); as a consequence, the nanocrystalline structure is disorganized (disordered solids are nonamorphous materials that have lost their long-range crystalline structure). Scanning electron microscopy analysis of the surface morphology of the formed nanofilms showed that the particles were all about the same size and spread out uniformly. Atomic force microscopy scanning images showed the nanofilms’ homogeneous surface morphology with granular shape. The optical properties showed a minor increase in absorbance spectra with increasing CuO doping. Contrarily, the optical energy gap ([Formula: see text]) was decreased by quantum confinement from 3.51 eV to 3.31 eV. As can be seen from the [Formula: see text]–[Formula: see text] characteristics, the solar cell’s conversion efficiency increases to 7.62% at [Formula: see text] mW/cm2 with a filling factor (FF) of 0.198, an open-circuit voltage of 12 V, and a short-circuit current of 3.2 mA.
Impact of Ag Nanoparticles on the Spectral and Optical Properties of Electrospun Nanofibrous Poly(vinyl alcohol)–Poly(acrylamide)
Authors: Rasheed Maher Hassan , Hashim Fouad Shakir , Abass Khalid Haneen
Published: March 2023

Nanofibers based on the polymer mixture that was associated with poly(vinyl alcohol) (PVA) and poly(acrylamide) (PAAm) (50/50 wt.%) doped with different ratios of silver nanoparticles (Ag NPs) were successfully synthesized using electrospun method, which was performed at room temperature (RT) and high voltage (12 kV). The products were studied using techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and ultraviolet–visible absorption spectroscopy. SEM results show uniform structures and a smooth surface without particles visible on the surface of the nanofibers. Also, SEM images show that the average diameter of polymer blend nanofibers is 157.40 nm and decreases with the increasing concentration of Ag NPs. The small capacity of the carbonyl group to operate as a powerful electron donor for interacting with [Formula: see text] cation is shown by the fact that the FTIR signal strength decreases with increasing dopant concentration, indicating an increase in the basicity of the major functional groups. The X-ray diffraction pattern results confirm the amorphous nature (nano-crystalline) of the PVA–PAAm. The XRD results show that the crystallite size increases with the increase of the concentration of Ag and the peaks of weak intensity at a concentration of 6% agree with Ag in the cubic structure. Indirect allowed and forbidden transition optical energy gap values decreased with increasing Ag NPs content. The effect of doping on the other parameters (absorption coefficients, refraction index and extinction coefficient) of different blend behavior was investigated in detail which qualifies them for solar cell applications.
Embedding procedure and wormhole solutions in Rastall gravity utilizing the class I approach
Authors: Malik Adnan , Ashraf Asifa , Mofarreh Fatima , Ali Akram , Shoaib Muhammad
Published: March 2023

This paper investigates the wormhole solutions in Rastall theory of gravity using the Karmarkar conditions. For this purpose, we choose a shape function (SF) that connects two asymptotically flat regions. We also discuss the wormhole configuration by plotting three-dimensional (3D) analysis of the embedding diagram in Euclidean space. Furthermore, we also observe the detailed graphical representation of energy conditions using the considered SF. The violation of energy conditions, especially null energy conditions (NEC), indicates the existence of exotic matter and wormholes. Hence, it can be concluded that our calculated results in the background of Rastall theory of gravity are viable and stable. The exciting feature of this work is the 3D analysis to discuss the viability of wormhole geometry
Temperature-Dependent Thermal Parameter Identification of Ceramic Nanorod Aerogels Composite in the Ultrahigh Temperature Environment
Authors: Shi Guanghui , Wu Wenhua , Lin Ye , Li Qiang , Lin Xiaohu , Mei Yue
Published: March 2023

The identification of the thermal properties of advanced materials is of great importance in engineering application. In this work, an inverse scheme is proposed to identify the temperature-dependent thermal parameters of ceramic nanorod aerogels (CNRAs) composite in the ultrahigh temperature environment up to 1873 K. The feasibility of the proposed method is successfully tested by an analytical solution for CNRAs with known material properties. Furthermore, the temperature-dependent thermal properties of CNRAs are successfully obtained using the experimental data acquired from the heat conduction experimental testing for a CNRAs plate. Lastly, the obtained thermal properties are used to simulate an arc-heated wind tunnel (AHWT) test of a receiving satellite antenna assembly using the FEM method. The simulated temperature at measured data has a very good agreement with the experimental data. This further demonstrates the strong capability of the proposed inverse method. In summary, the proposed approach provides an important approach for the identification of nonlinear and temperature-dependent thermal properties of advanced materials.
Elastic Properties and Damage Evolution Analysis for Lightweight Shale Ceramsite Concrete
Authors: Wang Shuren , Zhao Jianqing , Wu Xiaogang , Yang Jianhui , Wang Qirui
Published: March 2023

The damage behavior of lightweight aggregate concrete (LWAC) is different from that of normal concrete and mesoscopic simulation has been an effective method to understand the damage and failure process of LWAC. It is important for the reliability of simulation to determine the mechanical properties of individual constituents for LWAC. A micromechanical model of LWAC was proposed by utilizing the nearest-surface distribution functions, the generalized self-consistent scheme and a two-phase spherical model. The prediction method of elastic properties for lightweight shale ceramsite concrete (LWSCC) and an inverse method of parameter for each phase were also proposed. Based on a damage constitutive and a 3D mesoscale model, the damage process of LWSCC was analyzed. Results show that the elastic modulus of ITZ is about 0.70 times that of the cement. The damage caused by compression occurs earlier, but the damage caused by tension finally leads to the failure of the sample under uniaxial compression. The inversion method of elastic properties and damage evolution equations are available to study the damage process of LWAC.
Commutativity theorems on Lie ideals with symmetric bi-derivations in semiprime rings
Authors: Koç Sögütcü Emine , Gölbaşı Öznur
Published: March 2023

Let [Formula: see text] be a semiprime ring, [Formula: see text] a square-closed Lie ideal of [Formula: see text] and [Formula: see text] a symmetric bi-derivation and [Formula: see text] be the trace of [Formula: see text] In this paper, we shall prove that [Formula: see text] contains a nonzero central ideal if any one of the following holds: (i) [Formula: see text] (ii) [Formula: see text] (iii) [Formula: see text] (iv) [Formula: see text] (v) [Formula: see text] (vi) [Formula: see text] (vii) [Formula: see text] (viii) [Formula: see text] (ix) [Formula: see text] (x) [Formula: see text] (xi) [Formula: see text] and (xii) [Formula: see text], for all [Formula: see text]
Lacunary statistical convergence of rough triple sequence via ideals
Authors: Gürdal Mehmet , Kaya Emel , Savaş Ekrem
Published: March 2023

In this paper, we have introduced the notion of the lacunary [Formula: see text]-statistical convergence of triple sequences for rough variables. In addition, we have defined lacunary [Formula: see text]-statistical Cauchy sequence of rough variables in trust space and given the lacunary [Formula: see text]-statistical completeness for trust space. Some important results have also been examined.
Cauchy–Schwarz type inequalities in 2-Hilbert 𝒜-modules and its reverses
Authors: Vaziri Parvaneh , Khodabakhshian Hadi
Published: March 2023

We introduce the notion of 2-Hilbert [Formula: see text] modules and give some characterizations. The key idea is to consider a 2-Hilbert space instead of a Hilbert space. We employ our results to obtain reverse Cauchy–Schwarz and triangle inequality in this setting.
Combining Machine Learning and Semantic Web: A Systematic Mapping Study
Authors: Breit Anna , Waltersdorfer Laura , Ekaputra Fajar J. , Sabou Marta , Ekelhart Andreas , Iana Andreea , Paulheim Heiko , Portisch Jan , Revenko Artem , Teije Annette Ten , Van Harmelen Frank
Published: March 2023

In line with the general trend in artificial intelligence research to create intelligent systems that combine learning and symbolic components, a new sub-area has emerged that focuses on combining Machine Learning components with techniques developed by the Semantic Web community—Semantic Web Machine Learning (SWeML). Due to its rapid growth and impact on several communities in thepast two decades, there is a need to better understand the space of these SWeML Systems, their characteristics, and trends. Yet, surveys that adopt principled and unbiased approaches are missing. To fill this gap, we performed a systematic study and analyzed nearly 500 papers published in the past decade in this area, where we focused on evaluating architectural and application-specific features. Our analysis identified a rapidly growing interest in SWeML Systems, with a high impact on several application domains and tasks. Catalysts for this rapid growth are the increased application of deep learning and knowledge graph technologies. By leveraging the in-depth understanding of this area acquired through this study, a further key contribution of this article is a classification system for SWeML Systems that we publish as ontology.
Global Interconnect Optimization
Authors: Daboul Siad , Held Stephan , Natura Bento , Rotter Daniel
Published: March 2023

We propose a new comprehensive solution to global interconnect optimization. Traditional buffering algorithms mostly insert repeaters on a net-by-net basis based on slacks and possibly guided by global wires.

We show how to integrate routing congestion, placement congestion, global timing constraints, power consumption, and additional constraints into a single resource sharing formulation. The core of our algorithm is a new buffered routing subroutine. Given a net and Lagrangean resource prices for routing, timing, placement, and power, it computes a buffered Steiner tree. The resource sharing framework provides a special multiplicative price update for fast convergence.

Our algorithm is fast enough for practical instances. We demonstrate experimentally on 7nm microprocessor units that it significantly improves timing while reducing netlength and power consumption in an industrial design flow. Our implementation scales well under parallelization with up to 128 threads.
Factors Impacting Diversity and Effectiveness of Evolved Modular Robots
Authors: Pigozzi Federico , Medvet Eric , Bartoli Alberto , Rochelli Marco
Published: March 2023

In many natural environments, different forms of living organisms successfully accomplish the same task while being diverse in shape and behavior. This biodiversity is what made life capable of adapting to disrupting changes. Being able to reproduce biodiversity in artificial agents, while still optimizing them for a particular task, might increase their applicability to scenarios where human response to unexpected changes is not possible. In this work, we focus onVoxel-based Soft Robots(VSRs), a form of robots that grants great freedom in the design of both morphology and controller and is hence promising in terms of biodiversity. We useevolutionary computationfor optimizing, at the same time, morphology and controller of VSRs for the task of locomotion. We investigate experimentally whether three key factors—representation, Evolutionary Algorithm (EA), and environment—impact the emergence of biodiversity and if this occurs at the expense of effectiveness. We devise an automatic machine learning pipeline for systematically characterizing the morphology and behavior of robots resulting from the optimization process. We classify the robots into species and then measure biodiversity in populations of robots evolved in a multitude of conditions resulting from the combination of different morphology representations, controller representations, EAs, and environments. The experimental results suggest that, in general, EA and environment matter more than representation. We also propose a novel EA based on a speciation mechanism that operates on morphology and behavior descriptors and we show that it allows to jointly evolve morphology and controller of effective and diverse VSRs.
Second-Generation Functional Data
Authors: Koner Salil , Staicu Ana-Maria
Published: March 2023

Modern studies from a variety of fields record multiple functional observations according to either multivariate, longitudinal, spatial, or time series designs. We refer to such data as second-generation functional data because their analysis—unlike typical functional data analysis, which assumes independence of the functions—accounts for the complex dependence between the functional observations and requires more advanced methods. In this article, we provide an overview of the techniques for analyzing second-generation functional data with a focus on highlighting the key methodological intricacies that stem from the need for modeling complex dependence, compared with independent functional data. For each of the four types of second-generation functional data presented—multivariate functional data, longitudinal functional data, functional time series and spatially functional data—we discuss how the widely popular functional principal component analysis can be extended to these settings to define, identify main directions of variation, and describe dependence among the functions. In addition to modeling, we also discuss prediction, statistical inference, and application to clustering. We close by discussing future directions in this area.