Optimal Width Research Articles

Flow Field Analysis of a Turbulent Channel Controlled by Scalloped Riblets

Riblets are small protruding surfaces along the direction of the flow, and are one of the most well-known passive turbulent drag reduction methods. We investigated a scalloped riblet, the shape of which was constructed by smoothly connecting two third-order polynomials and was not as sharp in the tip as corresponding triangular riblets with the same height-width ratio. Numerical simulations were performed for turbulent channel flow with and without riblet control at an estimated optimum width of W+=20 and a height-width ratio of 0.5. A drag reduction rate of 5.77% was obtained, which is generally larger than the reported drag reduction rates of corresponding triangular riblets from the literature. Mean flow fields and second-order statistics of velocity, vorticity, and Liutex, a quantity introduced to represent vortices, were reported. It was found that streamwise vortices just above the riblet tips, which have a length scale of 200−300 in wall units, have an important influence on those statistics and thus the turbulence generation cycle and the drag reduction mechanism. Pre-multiplied energy spectra of streamwise velocity and the Liutex component were reported to reveal the length scales in the flow field. Instantaneous vortical flow fields visualized by the Liutex method were provided with emphases on the streamwise vortices just above riblet tips. It should be noted that the class of scalloped riblets is suitable for investigations on the influences of curvatures at the tip and the valley of the riblet in future.

Optic nerve thickening on high-spatial-resolution MRI predicts early-stage postlaminar optic nerve invasion in retinoblastoma.

To assess the diagnostic accuracy of nerve thickening on MRI to predict early-stage postlaminar optic nerve invasion (PLONI) in retinoblastoma. Furthermore, this study aimed to incorporate measurements into a multiparametric model for radiological determination of PLONI. In this retrospective multicenter case-control study, high-spatial-resolution 3D T2-weighted MR images were used to measure the distal optic nerve. Histopathology was the reference standard for PLONI. Two neuroradiologists independently measured the optic nerve width, height, and surface at 0, 3, and 5mm from the most distal part of the optic nerve. Subsequently, PLONI was scored on contrast-enhanced T1-weighted and 3D T2-weighted images, blinded for clinical data. Optic nerve measurements with the highest diagnostic accuracy for PLONI were incorporated into a prediction model for radiological determination of PLONI. One hundred twenty-four retinoblastoma patients (median age, 22months [range, 0-113], 58 female) were included, resulting in 25 retinoblastoma eyes with histopathologically proven PLONI and 206 without PLONI. ROC analysis of axial optic nerve width measured at 0mm yielded the best area under the curve of 0.88 (95% confidence interval: 0.79, 0.96; p < 0.001). The optimal width cutoff was ≥ 2.215mm, with a sensitivity of 84% (95% CI: 64, 95%) and specificity of 83% (95% CI: 75, 89%) for detecting PLONI. Combining width measurements with the suspicion of PLONI on MRI sequences resulted in a prediction model with an improved sensitivity and specificity of respectively up to 88% and 92%. Postlaminar optic nerve thickening can predict early-stage postlaminar optic nerve invasion in retinoblastoma. This study provides an additional tool for clinicians to help determine postlaminar optic nerve invasion, which is a risk factor for developing metastatic disease in retinoblastoma patients. • The diagnostic accuracy of contrast-enhanced MRI for detecting postlaminar optic nerve invasion is limited in retinoblastoma patients. • Optic nerve thickening can predict postlaminar optic nerve invasion. • A prediction model combining MRI features has a high sensitivity and specificity for detecting postlaminar optic nerve invasion.

Construction of Green Ecological Network in Qingdao (Shandong, China) Based on the Combination of Morphological Spatial Pattern Analysis and Biodiversity Conservation Function Assessment

Building urban green ecological network systems and increasing urban and rural landscape connectivity are effective ways to improve urban biodiversity and landscape sustainability. The ecological sources in the main urban area of Qingdao City (Shandong, China) were identified based on morphological spatial pattern analysis (MSPA) combined with a biodiversity conservation function assessment, with the ecological corridors established and the ecological network structure optimized. The results showed that (1) the study area lacked high-quality patches with strong landscape connectivity; (2) the potential green ecological network of the study area was composed of 38 ecological sources, 703 ecological corridors, and 284 ecological nodes, effectively connecting urban and suburban green spaces; (3) after optimization, the green ecological network contained a total of 223 important corridors and 61 key nodes, with significantly increased network connectivity; (4) the optimal ecological corridor width in Qingdao was determined to be 30 m. Our study provided important guidance for the construction of ecological security patterns and scientific evidence to support urban green space planning and sustainable development in Qingdao.

Construction of an ecological security pattern in Jiangnan water network area based on an integrated Approach: A case study of Gaochun, Nanjing

Rapid urbanization in the Jiangnan Water Network region has resulted in the degradation of ecosystems and interruption of ecological functions. The ecological security pattern (ESP) is crucial for balancing economic development and ecological protection within an area. In this study, we focused on a representative region of Gaochun in the Jiangnan water network area and devised a comprehensive ESP methodology. This study combined the importance of ecosystem services (ESI), landscape connectivity (Con), and ecological sensitivity (ESS), starting with an analysis of ecological sources. Furthermore, both natural and human factors are emphasized when constructing a comprehensive ecological resilience surface. Nighttime lighting data (NTL), ecological risk index (ERI), and land intensity factor (CI) were used to calibrate the resistance values. Finally, circuit theory was applied to determine the optimal path, width, and ecological strategy points for the ecological corridors. The results indicate We identified 39 ecological source areas, 74 ecological corridors, 33 ecological pinch points, and 45 ecological barriers. Based on this, an overall spatial optimization plan of “five cores, three patches, three belts, multiple corridors, and multiple points” is obtained. This study aimed to explore and optimize a comprehensive approach to ESP with regional characteristics, providing new pathways and decision support for the future construction of ecological security patterns in the Jiangnan Water Network region.

Effect of Grass Buffer Strips on Nitrogen and Phosphorus Removal from Paddy Runoff and Its Optimum Widths

Paddy runoff pollution is one of the major contributors to limiting the improvement of water quality in Taihu Lake Basin. Grass buffer strips (GBSs) are an effective measure to control paddy runoff pollution. However, most studies only consider a single inflow condition, and few studies have considered the effect of high-frequency rainfall. In this study, a field runoff simulation experiment was constructed to simulate the effect of GBSs on runoff nitrogen and phosphorus removal at different inflow volumes, inflow velocities, inflow concentrations, and rainfall frequencies. Results demonstrated that the larger the inflow volume, the faster the inflow velocity, and the lower the inflow concentration, the higher the runoff pollutant interception rate that occurred in GBSs, and the interception rate improved significantly with increasing GBS widths. The peak change point of removal rate occurred at a width of 15 m for NO3−-N and TP and at a 25 m width for TN and NH4+-N. The cumulative removal rate increased slowly after the change point. Although the peak cumulative removal rate appeared at a GBS width of 35~45 m. Considering the pollutants intercepted by GBSs and the emerging demand for land in this basin, 25 m was recommended as the optimum width to remove runoff pollutants.

Unveiling detection probability for multi-Gaussian correlated anomalous vortex modes in maritime atmospheric turbulence

In this study, we employ the Rytov approximation to investigate the detection probability of orbital angular momentum (OAM) in multi-Gaussian correlated anomalous vortex (MGCAV) beams under non-Kolmogorov maritime atmospheric turbulence. Our results demonstrate that the OAM detection probability of a MGCAV beam is influenced by various factors, including beam parameters and the characteristics of maritime atmospheric turbulence. Specifically, an increase in propagation distance, beam order, and beam index, or a decrease in inner scale, spatial coherence width, and non-Kolmogorov parameter, leads to a decrease in the OAM detection probability. The phase characteristics of partially coherent vortex modes are affected by both atmospheric turbulence phase and initial random phase, resulting in reduced robustness compared to fully coherent vortex modes. Furthermore, a comparative analysis between Gaussian–Schell correlated anomalous vortex (GSCAV) beams and MGCAV beams reveals the superior resilience of GSCAV beams in mitigating the impact of maritime atmospheric turbulence. Moreover, specific combinations of beam order, topological charge, and beam waist, or the optimal beam width, yield maximum OAM detection probability or minimum scintillation. These findings provide valuable insights applicable to optical communication, particularly in scenarios above sea and ocean levels.

Optimization and Application of Coal Pillar in Fully Mechanized Mining Face based on Energy Analysis

Based on the theory of energy dissipation, a numerical model of goaf excavation was established by FLAC3D based on the backflow channel of Heilong Coal Industry 2202. The dissipative energy distribution characteristics of coal pillars with different widths were studied, and the dissipative energy evolution law of surrounding rock of goaf roadway was analyzed. With the increase of the width of coal pillar, the width of elastic core zone is positively correlated with the bearing capacity. The peak value of dissipated energy density decreases with the increase of the width of coal pillar, and the concentration degree and region of dissipated energy density on the side of coal pillar are greater than that on the side of solid coal pillar. The project is applied to Heilong 2201 working face, and the optimum width of coal pillar and its supporting scheme are given. The practice results show that when the width of coal pillar is 5m, the deformation of surrounding rock can be effectively controlled and the demand for safe and efficient production can be met.

Force Transfer Mechanism and Behavior Insights for a Large-Diameter CFST Column to Steel Beam Connection

Concrete-filled steel tube (CFST) columns with internal ring-plate-reinforced connections are increasingly used in high-rise buildings. However, the behavior and optimal design of such large-scale connections is not well established. This study presents a numerical investigation of the structural performance of a ring-plate-reinforced CFST column to steel beam connection. The paper begins by reviewing a previous experimental study. Subsequently, nonlinear finite element models were developed and validated using the test results. Parametric analyses were conducted to evaluate the effects of the ring plate dimensions, friction coefficient, and concrete defects on the load transfer mechanism. The results showed that the ring plate and friction force together effectively transferred the beam load to the concrete core. An optimal ring plate width of 75 mm was identified. Concrete defects significantly reduced the load carrying capacity of the ring plate. The stress distribution in the concrete cross section transitioned from nonuniform to uniform over a length approximately equal to the column diameter. The connection design was found adequate for the prototype structure analyzed. The study provides valuable guidance for improving ring-plate-reinforced connection design in future construction.

Multipulse operation in Mamyshev oscillator: influence of external seed source

We study the influence of an external seed source on the startup of a fiber Mamyshev oscillator (MO). Depending on the seed source parameters, while keeping MO parameters fixed, we observe diverse mode-locked operations from the MO, generating stable single, double, triple and even up to a group of seven pulses. The probability of the occurrence of such mode-locked operations is studied. There can be different operating regimes in a particular multipulse operation. We find that there is an optimum spectral width of the seed source for which the probability of generating mode-locked stable train of single pulses from a fiber MO is maximum. Further, we find that the power of the seed source has less influence on the mode-locking state of the fiber MO; however, the probability of single or double pulse operation is relatively higher than that of multipulse operation at higher power of the seed source. These experimental observations will enrich the database of multipulse patterns and help in understanding pulse dynamics in the fiber MO. Suitably chosen seed source parameters can generate the desired pulse pattern. Such tailored outputs could have prospective applications in laser micromachining and high bit rate data transfer in optical networks.

Investigating the Influence of the Relative Roughness of the Riverbanks to the Riverbed on Equilibrium Channel Geometry in Alluvial Rivers: A Variational Approach

The roughness of a river’s boundary significantly influences the sediment transport process and the ultimate configuration of the river’s stable cross-section. This interplay between boundary roughness and river morphology is crucial to a river’s overall behavior and form. This study aims to analyze the influence of the relative roughness of riverbanks to a riverbed λ on the equilibrium form of alluvial rivers using a variational method. The results show the following: (1) As the parameter λ transitions from smaller to larger values, noteworthy variations are observed in a river’s characteristics. Specifically, there is a discernible reduction in the calculated maximum sediment discharge, coupled with a corresponding expansion in the optimal width–depth ratio. For instance, when λ changes from 1 to 0.1, the optimal width–depth ratio increases by 45%, while the calculated maximum sediment discharge experiences a decrease of 1.62%. (2) An examination of hydraulic geometric relationships, derived by assigning distinct values to the relative roughness of riverbanks to the riverbed, highlights the significant influence of this relative roughness on the ultimate equilibrium configuration of the river channel. Remarkably, this effect remains consistent and stands independently of other variables such as sediment discharge, flow discharge, channel gradient, and sediment size. (3) The critical and average hydraulic geometric relationships deduced in this study closely align with previous research findings. Notably, this research contributes to addressing the existing gap in understanding the mechanistic underpinnings of how river boundary conditions impact the equilibrium forms of rivers, thereby advancing our knowledge of river morphology. Nevertheless, it is imperative to emphasize that while this study provides valuable theoretical insights, the practical application of these findings in the context of river morphological evolution necessitates further in-depth research. It calls for a more comprehensive exploration of the transition from theoretical constructs to real-world applications, thus promoting a deeper understanding of the dynamics that shape river systems.

Improvement of agrotechnical conditions of growing paulownia in the Forest Steppe of Ukraine

Purpose. The purpose of the study was to improve the agrotechnical conditions for growing paulownia and its artificially bred variety Clone in vitro 112 in the Forest Steppe zone of Ukraine.&#x0D; Methods. Field, laboratory, visual, measuring and weighing, mathematical and statistical.&#x0D; Results. The article presents the results of research on the improvement of agrotechnical growing conditions and establishment of indicators of growth and development of paulownia plants in the Central Forest Steppe of Ukraine. The methods of planting, the optimal width between the rows, and the options for caring for the plantation of plants have been substantiated. It was established that in the first year of vegetation, the root system of paulownia plants is intensively formed. In order to obtain high-quality wood, after the first year of vegetation, it is necessary to make a technical cut at a height of 2–3 cm from the surface of the ground and remove young newly formed shoots (tillers). The highest trunk height of Clone in vitro 112 was formed in the first and second year of vegetation and reached 5–6 m. The optimal planting density is 625 plants per hectare. Conclusions. It was established that paulownia seedlings in vitro should undergo adaptation to the temperature conditions of the growing area for two to three weeks before planting in open ground.

Fabrication of Nitrogen Vacancy Center‐Doped Free‐Standing Diamond Photonic Devices via Faraday Cage‐Angled Etching

Herein, methods for the fabrication of monolithic diamond integrated photonic devices via Faraday cage‐angled etching of functional epitaxial diamond layers are presented. Optimal waveguide width is determined via simulation and the fabrication of nitrogen vacancy (NV) center‐doped microring resonators is demonstrated. The performance of the devices is verified via microphotoluminescence as well as cathodoluminescence scans of the in‐grown NV centers, revealing clearly visible cavity lines. The scalable fabrication method allows for the realization of large numbers of lateral waveguide structures as needed for future applications in integrated quantum sensing devices as well as novel spin‐based quantum computers.

Optimizing chaotic frequency electric fields for deformation analysis of droplets based on numerical modeling

Chaotic pulse group (CPG) electric field has already been proposed to achieve demulsification of water-in-oil (W/O) emulsions; however, the electric field parameters of the CPG electric field for efficient demulsification of emulsions are unknown. Therefore, in this study, the numerical model of droplet deformation under the action of electric field was established by coupling the flow field and electric field, and the effectiveness of the model was verified by comparing with the experimental results. In the numerical model, the electric field parameters are optimized by droplet deformation; moreover, the influence of surface tension and oil viscosity on the optimal electric field parameters is discussed; the deformation of droplets under the optimized CPG electric field was analyzed. The results show that when the droplet radius is 1 mm, the optimal electric field strength is 612 kV/m, the optimal pulse width is 0.023 s, and the optimal pulse rest width is 0.017 s. The increase in interfacial tension leads to the increase in optimal electric field strength, and the decrease in optimal pulse width and pulse rest width. The increase in oil viscosity leads to an increase in the optimal electric field parameters. With the increase in interfacial tension and oil viscosity, their influence on the deformation of droplets gradually decreases. Droplets of different sizes could find their own optimal electric field parameters in the CPG electric field, so as to achieve the maximum deformation. The results provide valuable guidance for the selection of electric field parameters in CPG electric field industrial applications.

Thermo–Solid Coupling Analysis of Bionic Piston for a Mud Pump in Tunnel Engineering

With the development of mud shield tunnel construction technology, the demands on the working performance of a mud pump are becoming higher and higher. As one of the critical components of a mud pump that is easy to wear, the performance of the piston directly affects the operational efficiency and lifespan of the mud pump. The bionic shape of the piston was designed under the guidance of non-smooth surface characteristics of natural organisms to enhance friction and wear performance as well as longevity. The stress field and temperature field characteristics of the pistons with three bionic structures (pit, stripe, and prismatic) were analyzed based on finite element simulation. The stress field analysis results indicated that, for the prismatic shape and pit shape pistons, the maximum stress was concentrated in the lip regions, and both of them bore large stress at the root. For the stripe-shaped piston, the stress was dispersed on both sides of the stripe structure, the stress at the root was small, and the stress gradient along the axial direction was relatively gentle. The stripe-shaped bionic structure can significantly improve the stress distribution state on the piston surface, and the optimal stripe width was recommended to be between 1 and 1.5 mm. The temperature field analysis results indicated that, for the stripe-shaped piston, the surface temperature and heat flux were the smallest, and the temperature gradient was relatively smaller than that of pit-shaped and prismatic-shaped pistons, so it was easier to dissipate heat. When the stripe width was 1.5 mm, the temperature distribution was the most uniform, and the heat flux in localized areas was the smallest, so the heat generated by friction was relatively easy to discharge in the unit area.

Synthesizing Non-Uniformly Excited Antenna Arrays Using Tiled Subarray Blocks

Conventionally, non-uniformly excited antenna arrays are synthesized by independently determining the excitation amplitude and phase of each single element. Such an approach is considered to be the most expensive and complex design method available. In this paper, the tilling technique is harnessed to synthesize non-uniformly excited antenna arrays. To apply this technique, the array elements are first divided into different subarray shapes, such as rectangles or squares known as tiles. The use of rectangular tile blocks instead of a single element architecture greatly simplifies the array design process and reduces array complexity. Next, the problem concerned with synthesizing sub-arrays comprising rectangular tile blocks is formulated and solved by using horizontal and vertical orientations of tiles having different shapes and sizes, and their larger integer expansions. The third approach to tiled design is a mixture of both previous tile architectures. A genetic algorithm is used to design such tiled arrays offering optimum sidelobe levels, beam width, directivity and taper efficiency. Simulation results demonstrated the effectiveness of the proposed tiled arrays.

Defect-Free Phononic Crystal Waveguides on GaAs

A phononic crystal waveguide is presented that consists of the inverse of a typical structure. Instead of a defect waveguide within an extended phononic crystal, this waveguide consists of a phononic crystal of finite width, and the phononic crystal itself is composed of a shallow array of holes. The acoustic velocity is actually reduced in the phononic crystal region, which subsequently enables the waveguiding of the acoustic wave underneath the micro-structured surface. As the width of the waveguide increases with the number of inclusions, the waveguide morphs from an unstructured surface to an extended phononic crystal with a transitional modal region of an intermediate number of inclusions that is suitable for waveguiding. For the chosen phononic crystal parameters in terms of the hole depth and filling fraction, the optimum waveguide width of four inclusions is determined.

Exploring optimal graphene slit-pore width for the physical separation of water-methanol mixture

Efficient and sustainable techniques for separating water- alcohol mixtures are in high demand in the industry. Recent research has revealed that nanotechnology could be the optimal solution. In this study, we investigate how the width of a nano-confining graphene slit-pore affects the filtration and purification of water-methanol mixtures. Using Molecular Dynamics simulations of a coarse-grained model for mixtures containing up to 25 percent methanol, we found that specific pore sizes segregate the two components, with water being preferred in the center and methanol accumulating near the hydrophobic walls. Altering the pore width also affects non-monotonically the diffusivity of each component, with water diffusing faster than methanol. Hence, optimal pore size, leveraging segregation and diffusion differences, can enable the successful extraction of both components. However, the system requires external forces and work to maintain mechanical stability at specific pore widths. Our research indicates that 12.5Å pore size maximizes physical separation, ensuring that the energy cost of a filtering graphene membrane is minimized.

Multiple similarity measure-based maximum correntropy criterion Kalman filter with adaptive kernel width for GPS/INS integration navigation

The filter based on the maximum correntropy criterion (MCC) has low sensitivity to non-Gaussian noise, which can effectively improve the robustness of the filter. However, the uncertainty of kernel width restricted the application of the maximum correntropy criterion Kalman filter (MCCKF) in the integrated navigation system. In order to overcome the above difficulty, this paper proposes a multiple similarity measure-based maximum correntropy criterion Kalman filter with adaptive kernel width (ABMCCKF). ABMCCKF uses the MORKF framework and distinguishes the noise polluted by outliers through a designed protecting window, which also ensures that the kernel width is compatible with the noise pollution level. Through the window, ABMCCKF utilizes the optimality of both MCC and the minimum mean square error criterion (MMSE). Simulations and vehicular experiments are used to verify the effectiveness of the method. The results show that the ABMCCKF have a good performance when the optimal kernel width is uncertain.

Numerical calculation for instability criterion of tearing modes influenced by energetic ions

The instability criterion of tearing modes, including the effects of circulating energetic ions (CEIs), is numerically solved through an iterative method and fast Fourier transform algorithm. The influence of beta (the ratio of pressure to the magnetic pressure) profile of CEIs and magnetic shear on instability criterion of the tearing modes are investigated systematically. CEIs impact the tearing modes through altering the total perturbed parallel current density, and the gradient of their beta profile at the rational surface (the location of tearing mode) plays an important role. The effect of CEIs on tearing modes depends on the deposition position and the toroidal circulating direction of CEIs. Specifically, the on-axis peaked co-CEIs have a stabilizing effect on tearing modes. For off-axis peaked co-CEIs, in order to stabilize the tearing modes, the deposition position of co-CEIs should be located between the magnetic axis and rational surface, and there is an optimal peak width and deposition location where the stabilizing effect is strongest. For counter-CEIs, they would destabilize the tearing modes when the deposition position is located between the magnetic axis and rational surface. However, if the deposition position is located near the outside rational surface, counter-CEIs have a stabilizing effect on tearing modes. Furthermore, there exists a critical deposition position for CEIs. Whether CEIs plays a stable role or an unstable role depends on the deposition position within or outside the critical deposition position. The critical deposition position is related to the orbital width of CEIs. Finally, the magnetic shear can stabilize the tearing modes, but the effect of co-CEIs on tearing modes is weakened as the magnetic shear increases.

The thickness and width of the intrinsic region effected electrical properties of GaAs p-i-n photodiodes

The thickness of the p-i-n photodiode's p and n contacts, as well as the width of the semiconductor device, affect the conductivity performance of the diode. In this study, the impact of thickness and width variations of GaAs p-i-n photodiode devices on their performance was investigated using the COMSOL Multiphysics software, which enables simulations of multiple physical fields. The terminal current and field strength at various positions were calculated for different thickness and width values. The mechanisms behind the influence of thickness and width variations on the conductivity performance were explained, and a detailed description of the distribution of terminal current and electric field magnitude was provided. Based on experimental data, the optimal thickness and width for achieving peak conductivity performance of the diode under material-saving conditions were determined, providing theoretical guidance for the preparation of efficient and stable GaAs p-i-n photodiodes.