Symmetric Grooves Research Articles

Aerodynamic performance and wind-induced response of carbon fiber-reinforced polymer (CFRP) cables

To study the aerodynamic performance and wind-induced response of carbon fiber-reinforced polymer (CFRP) cables, CFRP cable was designed by replacing a steel cable in a tied arch bridge based on stiffness, strength and area equivalent criteria, respectively. The aerodynamic performance and wind-induced response of CFRP cable and steel cable were studied and compared by computational fluid dynamics (CFD) model. Based on the computational results, optimal cable replacement criterion was proposed for CFRP cable to replace steel cable. In addition, surface modification was conducted by engrooving vertical symmetric (VS), vertical asymmetric (VA) and helical symmetric (HS) V-shaped grooves to improve the aerodynamic performance and wind-induced response of CFRP cable. Results showed that CFRP cables exhibited inferior aerodynamic performance and wind-induced response in most cases. However, CFRP cable based on stiffness equivalent criterion exhibited better aerodynamic performance and wind-induced vibration properties compared to the other two cable replacement criteria, thus is regarded as the optimal substitute for steel cable. In addition, HS grooves generated symmetric disturbances and caused approximately equivalent boundary layer separation delays uniformly and continuously along the cable length, thus exhibiting better effect in decreasing the reverse flow region, the maximum negative flow velocity, the vortex shedding frequency and the wind-induced vibration amplitude of CFRP cable. Hence, the stiffness equivalent criterion combined with surface modification with HS V-shaped grooves was proposed to replace steel cable with CFRP cable. This study can provide insights into the aerodynamic performance and wind-induced response of CFRP cable and instructions for cable replacement practice.

An Optimization of Grooves Structure for Thermal Performance Enhancement in Microchannel Heat Sink

In the current work, the thermal performance of a grooved microchannel heat sink is evaluated at different offset positions inside the channel. For this purpose, the Eulerian–Eulerian approach-based mathematical model is developed and is numerically solved using the finite volume approach. Water is the base fluid to which alumina nanoparticles were added to enhance heat transfer. The effect of the Reynolds number (100–1,000), particle diameter (10–50 nm), the number of grooves (10–80), offset between the grooves (0–1), and particle volume fraction (0–5%) on the dimensionless pressure drop, Nusselt number, and coefficient of performance are investigated, and their impact on the microchannel’s thermal characteristics is quantified. Most importantly, the microchannels with symmetric (Offset = 0) and asymmetric grooves (Offset ≠ 0) were compared, and it was found that offsetting the grooves has an insignificant effect on the microchannel performance. Furthermore, an empirical correlation is proposed to evaluate the coefficient of performance of both symmetric and asymmetric microchannels as a function of the output variables.

Quantifying cooperative multisite binding in the hub protein LC8 through Bayesian inference.

Multistep protein-protein interactions underlie most biological processes, but their characterization through methods such as isothermal titration calorimetry (ITC) is largely confined to simple models that provide little information on the intermediate, individual steps. In this study, we primarily examine the essential hub protein LC8, a small dimer that binds disordered regions of 100+ client proteins in two symmetrical grooves at the dimer interface. Mechanistic details of LC8 binding have remained elusive, hampered in part by ITC data analyses employing simple models that treat bivalent binding as a single event with a single binding affinity. We build on existing Bayesian ITC approaches to quantify thermodynamic parameters for multi-site binding interactions impacted by significant uncertainty in protein concentration. Using a two-site binding model, we identify positive cooperativity with high confidence for LC8 binding to multiple client peptides. In contrast, application of an identical model to the two-site binding between the coiled-coil NudE dimer and the intermediate chain of dynein reveals little evidence of cooperativity. We propose that cooperativity in the LC8 system drives the formation of saturated induced-dimer structures, the functional units of most LC8 complexes. In addition to these system-specific findings, our work advances general ITC analysis in two ways. First, we describe a previously unrecognized mathematical ambiguity in concentrations in standard binding models and clarify how it impacts the precision with which binding parameters are determinable in cases of high uncertainty in analyte concentrations. Second, building on observations in the LC8 system, we develop a system-agnostic heat map of practical parameter identifiability calculated from synthetic data which demonstrates that the ability to determine microscopic binding parameters is strongly dependent on both the parameters themselves and experimental conditions. The work serves as a foundation for determination of multi-step binding interactions, and we outline best practices for Bayesian analysis of ITC experiments.

Application of two-arm welding robot control system based on PLC

Understanding the current industrial production process, forklift manufacturing line of symmetrical groove workpiece welding link emerged a lot of problems, such as waste productivity is getting higher and higher, practical work efficiency is getting lower and lower, the work intensity of the department staff is getting greater and greater, the requirements of welder skills become higher. In order to solve these problems scientifically, Chinese scholars proposed a two-arm industrial robot which can realize automatic workpiece welding. Based on the understanding of the status quo of the application research of welding robots, combined with the design thinking of the dual-arm welding robot control system based on PLC as the core, the application effect of this control system is discussed from the perspective of practical application, in order to improve the automation and intellectualization level of our industrial field, and ensure the quality and efficiency of production and manufacturing workpiece.

Numerical investigation of vortex-induced vibrational responses to a flexible tensioned riser with symmetric grooves in uniform currents

The vortex-induced vibration (VIV) responses to a flexible tensioned cylindrical riser, which the cross section is fixed with two symmetric grooves, is numerically researched by the inhouse viv3D-FOAM-SJTU solver developed based on the OpenFOAM and thick strip model. The Reynolds-averaged Navier-Stokes (RANS) method and Euler-Bernoulli bending beam model are coupled to obtain the hydrodynamics forces and displacements in the vibration process of riser exposed to uniform current. The configurations of riser are designed to spanwise grooves with three different angles (45°,90°, 135°) to the incoming flow, and the three different groove depths and four flow velocities are selected for further investigation. Results show that the flow is broken in the groove, forming the internal small vortices, when the groove degree is 45°, the complex VIV responses are generated due to the change of flow separation point and the interference of internal small vortices on the development of large-scale vortices on the surface of the riser. As the groove degree reaches to 90°, the interference of internal small vortices leads to VIV suppression, and the internal small vortices is released directly into the wake field to enhance VIV with the groove degree = 135°. As the depth of the groove increases, the effect on the flow field is also enhanced, and the vortex structure along the span of the flow field is affected by the position and depth of the groove. Therefore, the geometries of the groove degree = 90° and depths = 0.12D, 0.16D (D is the riser diameter) present the best VIV suppression effect, and the configurations of two other groove degrees are failed to suppress the VIV well.

Design and Experiment of Quantitative Seed Feeding Wheel of Air-Assisted High-Speed Precision Seed Metering Device

Aiming to solve the problems of the poor uniformity of seed flow discharge and serious damage of traditional straight grooved wheels to improve the performance of air-assisted maize high-speed precision seed metering devices, a staggering symmetrical spiral grooved feeding wheel with maize seeds was designed. To explore the influence of the spiral groove inclination angle and the length of the staggered symmetrical spiral groove feed wheel on the uniformity of seed flow discharge, the spiral groove length l and the spiral groove inclination angle ρ were used as the experimental factors, and the variation coefficient of the increase in seed, a full-factor simulation test was carried out for the test indicators, and it was found that both the inclination angle and the length of the spiral groove have an influence on the uniformity of seed flow discharge, and the influence of the inclination angle of the groove is more significant. Comparing the force of a single seed in the traditional straight grooved wheel and that of the spiral feeding wheel, it is found that the staggered symmetrical spiral grooved feeding wheel can reduce the damage of seed fertilizer. Through a bench test, the spiral groove length was found to be 50 mm, and the groove inclination angles are 30°, 45° and 90°. The test results show the variation trend and simulation results of the fluctuating coefficient of variation of the seed flow discharge in the bench test. The trend of change is basically the same. The inclination angle of the spiral groove is 45° and the uniformity of seed flow discharge is the best when the groove length is 50 mm, indicating that this structure can effectively improve the uniformity of material discharge, and the variation coefficient of seed flow discharge fluctuation is 3.12% and the seed breakage rate is 0.69%. Through the seeding performance test, it is verified that the staggered symmetrical spiral grooved feeding wheel can improve the seeding performance of the pneumatic high-speed precision metering device. When the metering device runs smoothly, the qualified rate reaches more than 90%, and the leakage rate is reduced to 0%. Therefore, the results of this study can provide a reference for research on uniform seeding, drill seeding and the uniform application of granular fertilizer.

PO26 Presentation Time: 7:40 AM: Dosimetry Accuracy of a Model-Based Dose Calculation Algorithm in Modeling a Novel Direction Modulated Brachytherapy Tandem Applicator for the Cervical Cancer

<h3>Purpose</h3> A novel shielded tandem applicator for the direction modulated brachytherapy (DMBT) was previously introduced, which showed capability to improve the coverage of nonuniform targets and organs at risk in cervical cancer. This applicator has been recently modeled in a commercial treatment planning system (TPS - BrachyVision ACUROS^TM (BVA)), a Model based Dose Calculation algorithm (MBDCA), for the clinical research. In this study, we aim to benchmark the accuracy of the TPS in modeling the DMBT tandem using Monte Carlo (MC) simulations. <h3>Materials and Methods</h3> The DMBT tandem applicator, made of an MR compatible tungsten alloy with six symmetrical grooves covered by a sheath of PEEK plastic, was simulated in GEANT4 MC code. Subsequently, two scenarios were created using the BVA TPS and reproduced by GEANT4 MC simulations, including ‘source at the center of the water phantom' and ‘source at the middle of the applicator' for the cubical phantoms with dimensions of (20 cm)³, (30 cm)³, and (40 cm)³. A track length estimator (TLE) was then utilized to estimate the dose deposited inside the water phantoms and 2D/3D scoring were performed. Volumetric dose comparisons of the TPS against MC results were further implemented. <h3>Results</h3> There were different level of agreements between the TPS and MC results for the different phantom sizes. The best agreement, however, was achieved for the phantom (40 cm)³, such that the dose difference fell in the intervals [0% 8.5%] and [-6.5% 6.5%] in 95% of the voxels, for the ‘source at the center of the water phantom' and ‘source at the middle of the applicator', respectively. In addition, the dose difference was within for all phantoms, within 5 cm from the center of the HDR sources. <h3>Conclusions</h3> The results of this study indicated that the accuracy of the TPS in dose calculation depends on the phantom size. Nevertheless, it seems the TPS could still provide satisfactory accuracy inside the area of clinical importance.

Temperature and vibration-assisted effects in nanoimprint gold: An atomistic study

This study surveys the effects of taper angle, temperature, vibration, and grain size on the groove formation of the NIL process of a gold substrate. The results indicate that the taper angle has a great impact on the residual stress and groove depth. Imprinting with a taper with angles of 10°, 15°, and 45° could obtain a deep and symmetrical groove. In addition, imprinting at 300 K–500 K could generate a good groove shape. In the range of 300 K–600 K, the temperature does not strongly affect the structure change rate. Besides, imprinting at a vibration amplitude of 2.5 Å-5 Å, a deep and good groove shape can be generated. At the same time, increasing the vibration frequency gives rise to the groove depth. The grain size strongly affects the deformation and phase transformation rate. Increasing the grain size from 3 nm to 7 nm leads to a decrease in the phase transformation rate and an improvement in the groove depth. The grain size is the strongest factor that affects the shape and the phase transformation of the gold substrate compared to other factors. The taper angle, temperature, and vibration factors also have a strong effect on the groove shape. However, they have a lower rate of effect on the phase transformation than the grain size.

Numerical Simulation of Convective Diffusion of Point Particles in a Laminar Flow Past a Row of Profiled Hollow Fibers

The numerical modeling of transverse laminar flow past a new type of hollow-fiber membranes with external profiling has been performed. A model system of parallel fibers with symmetrical parallel protrusion obstacles or grooves is considered. The absorption of point particles (solute or gas molecules) from a laminar transverse flow of a viscous incompressible liquid (gas) is calculated for a row of fibers, and the dependences of the efficiency of retention of particles by fibers on the Peclet (Pe), Reynolds (Re), and Schmidt (Sc) numbers and on the distance between neighbor fibers in a row are determined. The flow velocity and concentration fields are calculated by numerical solution of the Navier–Stokes equations and the convective diffusion equation in a wide range of Peclet numbers Pe = 0.1 − 105 for Sc = 1, 10, 1000 and Re ≤ 100.

Research on a rectangular microwave filter with rectangular groove

In this paper, a rectangular microwave filter with rectangular groove is designed. The filter adopts symmetrical three-stage structure. The first section is the slot line waveguide section to realize the input / output of microwave signal, the second section is the transition section, which adopts the impedance gradient structure, and the third section is the sspps section composed of periodic symmetrical rectangular groove and 90 degree bending structure. By adjusting the geometric size of the rectangular groove and its air gap, the passband width and stopband characteristics of the filter can be adjusted, and its microwave sub wavelength binding effect can be further improved, making the anti space electromagnetic interference ability of sspps filter more excellent. The filter can be applied to L ∼ s Band civil microwave communication system.

Application of a staggered symmetrical spiral groove wheel on a quantitative feeding device and investigation of particle motion characteristics based on DEM

The uniformity of particle flow is the key to the research of quantitative feeding devices. Ensuring particle motion characteristics will help improve the working performance of the device. In this work, a quantitative feeding device with a staggered symmetrical spiral groove wheel is studied by using the DEM method. The effects of the inclination angle and the length of the staggered symmetrical spiral groove wheel on the uniformity of particle flow are examined and analyzed. The results show that with the decrease of the inclination angle, the change of particle discharge method from passive pushing to active sliding, the uniformity of particle flow is improved. A small inclination angle results in less disturbance of seed particles and reduces the uniformity of particle flow. When the feeding rate is constant, shortening the length of the grooved wheel (corresponding to increasing the rotational speed) causes shorter filling time and more leakage filling. Compared with the traditional straight groove wheel and spiral groove wheel, the force on the seed particles is smaller. The appropriate inclination angle and length (e.g.,45°, 50 mm) can effectively enhance the uniform stability of seed particle flow, reduce the risk of seed particles damage, and improve feeding performance.

Highly Sensitive Curvature and Temperature Sensor Based on Double Groove Structure and Hollow Core Fiber

In this paper, we propose a curvature and temperature sensor based on two symmetrical grooves and a hollow core fiber (HCF) filled with polydimethylsiloxane (PDMS). The two grooves are produced by splicing both ends of the polished HCF with two multimode fibers (MMFs). The proposed groove structure is sensitive to curvature, and the PDMS, with a high thermo-optical coefficient, makes the sensor highly sensitive to temperature. The experimental results show that the sensor exhibits a high sensitivity of −6.833 nm/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> in the curvature range of 0 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> to 45.97m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> , and a high sensitivity of 4.278 nm/°C in the temperature range of 25°C to 95°C. The proposed sensor can monitor curvature and temperature simultaneously in real-time, and has potential application prospects in industrial production, biomedicine, structural health monitoring, and other fields.

Surface Plasmonic Waveguide Developed from Glide Symmetric Dumbbell Grooves and Its Application in Microwave-Frequency Wideband Filters

Surface Plasmonic Waveguide Developed from Glide Symmetric Dumbbell Grooves and Its Application in Microwave-Frequency Wideband Filters

Wideband VHF/UHF Wing Conformal Vertical Polarized Omnidirectional Antenna

This letter proposes a novel wideband wing conformal vertical polarized omnidirectional antenna for the very high frequency&#x002F;ultrahigh frequency band. The antenna adopts symmetrical radiation and feed structures to obtain quasi-omnidirectional radiation. To be conformal with the ultrathin body of the wing, this construction is realized using double-layer flexible metal films that cover the surface of the wing. Moreover, there are several symmetric grooves on the upper metal film that are beneficial to improve the efficiency of radiation. The upper and lower metal films are connected by two shorting plates with same exponential gradual outline for vertical polarization and wideband potential. The ultrawide operating band can be realized by loading resistors and inductors. A conformal prototype of the antenna was fabricated and validated. The wing thickness determines the profile, which is only 0.013 <i>&#x03BB;_L</i>, where <i>&#x03BB;_L</i> is the wavelength at the lowest operating frequency. Its acquired bandwidth ranges from 100 to 600 MHz; high radiation efficiency and vertically polarized quasi-omnidirectional characters are also obtained in this band.

A compact wide-angle frequency beam-scanning antenna using modulated composite waveguide based on half-mode substrate integrated waveguide and spoof surface plasmon polariton structure

In this paper, we present a novel frequency beam-scanning leaky-wave antenna (LWA) based on a composite half-mode substrate integrated waveguide/spoof surface plasmon polariton (HMSIW/SSPP) waveguide. The new composite HMSIW/SSPP waveguide is accomplished by embedding periodical symmetric subwavelength grooves on both copper surfaces of the HMSIW, which owns flexible transmission characteristics attributed to its features from both HMSIW and SSPP. The conversion of propagating slow-wave mode to radiation mode is devised by a double-sided symmetric sinusoidal modulation method with a π/2 displacement between the top- and bottom-surface. This double-sided modulation method not only offers a compact structure but also effectively eliminates the open stopband. A prototype of the proposed antenna is fabricated and measured to verify the predicted performance from simulation. Experimental results show that the proposed antenna achieves a continuous wide scanning range of 125° from backward to forward for lateral unidirectional radiation with an average peak gain level of 9.1 dBi from 6.3 to 9.7 GHz. And the compact antenna volume of 0.40 × 8.0 × 0.013 λ03 offers a well scanning rate (36.8°/GHz) and a very high gain value per unit volume (219 dBi/λ03).

Thorough computational analysis of the staggered herringbone micromixer reveals transport mechanisms and enables mixing efficiency-based improved design

The problem of mixing of solutions of biomolecules in the famous staggered herringbone micromixer (SHM) is revisited through a computational study with the focus on two overlooked aspects, namely the accuracy of the numerical solution and the thorough analysis of the mixing process. The study is based on the numerical solution of the continuity and Navier-Stokes equations and the mass balance of the solute. The numerical instabilities, induced by the high Péclet number (extremely low diffusion coefficient of biomolecules), are handled with stabilization methods and the accuracy is ensured by a) dense adaptive meshes constructed by an error criterion and b) systematic studies of the mesh independence of the numerical solution. The importance of the accuracy on the calculated mixing efficiency (ME) and the design of the SHM is demonstrated through a comparison with the results for non-adaptive and coarse meshes. The ME versus the length of the SHM is compared with experimental data for the first time, with the mesh independent solution in good agreement with them. The thorough analysis brings to light symmetries and periodicities in the velocity field and explains the inflection point of the ME versus the length of the SHM, observed in experimental and computational studies. Without an optimization algorithm, designs which increase the ME up to 100% and reduce the mixing length are proposed. In particular, the mixing length is reduced a) by 8% through the introduction of symmetric grooves in the SHM, b) up to 39%, if the bottom of the SHM is made slippery, and c) up to 49% by adding symmetric grooves in case (b). The effect of the designs on the chaotic advection is demonstrated.

Phase-field simulations of grain boundary grooving under diffusive-convective conditions

Grain boundaries are potential sites for the development of morphological instabilities along a solidifying interface, and play an important role in the microstructural properties of cast alloys. In the present study, we employ a multiphase-field model to address the grain boundary grooving phenomenon under the cooperative effect of convection and volume diffusion in the liquid phase. Under pure diffusive conditions, we first benchmark our phase-field model by illustrating and comparing the formation of symmetric groove profiles across the grain boundary with Mullins’s groove. In the presence of an additional convective transport mechanism, we systematically depict that the asymmetricity of groove profile increases with the increase in the convection velocity. Particularly, it is identified that the groove kinetics as well as the grain boundary grooving mechanism is significantly modified in the diffusive-convective regime. The present two-dimensional simulations, while providing considerable insights into the mechanism of grain boundary grooving, also closes the gap with the experimental and theoretical observations reported earlier. In addition, the role of relative surface energies on the groove deepening along with the ridge morphology is discussed in detail. The simulated grain boundary features are of practical significance for understanding and controlling the nanocrystalline thin film experiments.

Numerical analysis of hydroenergy harvesting from vortex-induced vibrations of a cylinder with groove structures

The energy generated by vortex-induced vibrations is studied through numerical simulation, and the vibration characteristics of the energy-harvesting device are studied using a bidirectional coupled fluid-structure simulation. The energy collector consists of an elastic cylinder with symmetrical grooves, which can effectively improve the energy extraction performance. The studied range of Reynolds numbers is 15 000 to 100 000 (1.86 <U*water< 11.63). The performance of the energy collector can be significantly affected by modifying various parameters of the grooved structure. Moreover, changing the damping ratio ζn will also affect the energy harvesting. The results show that the grooves affect the dynamic response of the structure; the structure will gallop when the angle between the grooves and the inflow direction is α = 30°. For a grooved cylinder with α = 30° or 60°, the effective power Pharn of the system can be effectively increased, and the grooves can also effectively increase the energy conversion rate ηviv; especially in the case of structure galloping, more energy can be collected, and Pharn and ηviv can be dramatically increased. Immediately after the structure has entered the lock-in region, ηviv reaches its maximum. Varying ζn has little effect on the amplitude of the conductor, but it can effectively enhance energy harvesting and energy conversion.

Tunable broadband terahertz absorber using a single-layer square graphene patch with fourfold rotationally symmetric groove

We present a broadband and tunable graphene-based absorber in the terahertz (THz) region, which is composed of a monolayer of graphene square-shaped patch with fourfold rotationally symmetric groove and a metallic ground film separated by a silicon dioxide (SiO2) spacer layer. The bandwidth of 90% absorbance for the structure reaches up to 1.66 THz with a central frequency of 2.53 THz under normal incidence, and the broadband absorption still remains 80% over a wide incident angles up to 50° for both transverse electric (TE) and transverse magnetic (TM) modes. Furthermore, the peak absorption of the proposed absorber can be tuned from 15% to near 100% by varying the graphene's Fermi energy from 0 to 1.0 eV via adjusting the bias voltage of the graphene layer or chemical doping. Due to the geometrical symmetry, the proposed structure is insensitive to the polarization state of incidence wave. Benefits from these outstanding performances, we believe that our proposed absorber may have great applications in tunable THz filtering, imaging, and cloaking.

Determination of the time-dependent thermal grooving coefficient

Changes in morphology of a polycrystalline material may occur through interface motion under the action of a driving force. An important special case that is considered in this paper is the thermal grooving that occurs when a grain boundary intersects the flat surface of a recently solidified metal slab giving rise to the formation of a thin symmetric groove. In case the transient surface diffusion is the main forming mechanism this yields a fourth-order time-dependent partial differential equation with unknown time-dependent surface diffusivity. In order to determine it, the profile of the free grooving surface at a fixed location is recorded in time. The grooving boundaries are supported by self-adjoint boundary conditions. We provide sufficient conditions on the input data for which the resulting coefficient identification problem is proved to be well-posed. Furthermore, we develop a predictor–corrector finite-difference spline method for obtaining an accurate and stable numerical solution to the nonlinear coefficient identification problem. Numerical results illustrate the performance of the inversion of both exact and noisy data.