Straight Edge Research Articles

Performance analysis of novel V-shaped turbine blade profile by three-dimensional numerical investigations with varying overlap ratios for hydropower application

In the present paper, three-dimensional numerical simulations were carried out to examine the influence of the overlap ratio between the two straight edges on the advancing and returning blades of the novel V-shaped rotor blade profiles using the sliding mesh technique. The performance parameters were computed with respect to the tip speed ratio. The findings show that the coefficient of torque and power for the novel V-shaped turbine blade is maximum for the zero-overlap ratio compared to the turbine blade, with an overlap ratio ranging from 0.05 to 0.3. The blade profiles' flow field was visualized at different angular positions, and various significant zones developed during the turbine blade rotation were captured and analyzed. The new overlapping jet developed between the two straight edges of the advancing and returning blade profiles as the overlap ratio varies from 0.05 to 0.3. Therefore, the turbine's performance is reduced due to the development of an overlap jet as it travels parallel to the straight edges of the blade profile and does not impact the rear side of the returning blade profile.

Effect of subsoiler plow leg shape, tillage depth, and tractor speed on some of field Performance Indicators and yield of oats

A field experiment was carried out in the College of the Agriculture / University of Basra to study the effect of four types of subsoiler leg shapes, three tillage depths, and three tractor speeds in draft force, slip percentage, fuel consumption, and mean weight diameter (MWD). A randomized complete block design was used in a factorial experiment for data analysis. The results showed that the serrated edge of 45-degree angle surpassed on straight, serrated edge, 70-degree angle serrated edge, and curved in oat yield by a percentage of 2.4,18 and,21% respectively. However, serrated edge of 45-degree angle recorded less draft force, lower slip percentage, fuel consumption, and main weight mean diameter while the highest values of the previous characteristics were for the straight edge. The results showed that increasing tillage depth led to increasing slip percentage, fuel consumption, and draft force, also the previous characteristic increased with increasing forward speed. It was concluded that the best combination was obtained when using a 45-degree angle serrated edge and the speed of 2.34 km / h which gave the lowest fuel consumption of 8.11 liters/ha. Also, the 45-degree angle serrated edge at 10 cm tillage depth gave the lower fuel consumption of 8.78 liters/ha. Keywords: Subsoiler legs, draft force, fuel consumption, slip percentage, mean weight diameter, oat.

Bayesian analysis for geometric shapes in additive manufacturing

In additive manufacturing, geometric shape deviations are built through statistical deviation models. Nonetheless, the resource constraints limit the manufacturers to test shapes. However, in addition to the power, the simplicity of the deviation models has been demonstrated with illustrative cases for in-plane deviation modelling for regular pentagon, irregular octagon as well as straight edges in free-form shapes utilizing only data and models for single regular pentagon and cylinders. Bayesian deviation models, built for geometric shapes, provide a better fit on the data and help in achieving better predictive accuracy. The main aim of this study is to assess the effect of the error distribution, generally assumed as the normal, and evaluate its impact on the deviation model. In particular, we consider Laplace, logistic, Cauchy, and exponential distributions for the errors. It is shown that logistic distribution provides better alternative error distribution for deviation models as compared to the normal distribution.

Geometric Modeling of Serrated Cutters for Endmilling Forces using Local Oblique Cutting and Rake Normal Correspondence

For nonstandard endmills with sinusoidal and circular serrations on nominally helical cutting edges, the edge space curve was subdivided into straight edge elements for constant increments of arc length. To calculate the local normal rake angle at the serrated edge point, Local Rake Normal Correspondence used the normal vector on the rake face of the corresponding unserrated helical edge point at the same axial cross section. Uncut chip thickness h was computed under Local Oblique Cutting Correspondence published earlier. Stabler’s rule specified chip flow direction and Lazoglu mechanistic normal and friction force coefficients completed the straight edge cutting element forces. Local force contribution vectors summed over the tool engagement resulted in global tool forces. Number of straight edge element computations were minimized with the hypotheses (a) cutting predominantly occurs at the vicinity of serration tips and (b) only the stock surfaces swept by flutes immediately prior and following the current flute need be considered for h. Interaction of axial cross sections at a significant fraction of the serration wavelength was noted. Thus, treating tool axial subdivisions in relative isolation for h is untenable. However, local normal rake angle on the serrated edges followed earlier published trends. For a square endmill, sinusoidally serrated, cutting with low axial depth of cut ADOC, modeled forces showed idle periods and unbalance fluctuations during a full rotation, but not the data; modeled forces for an identical unserrated helical cutter were lower than the serrated. For the same endmill with circular serrations cutting at high ADOC, no idle periods or unbalance were predicted and the agreement with published data was better.

Teğet Sınır Şartlarının Ortasından Tekil Yüklü Katmanlı Kompozit Silindirik Panellerin Nonlineer Davranışlarına Etkisi

In this study, the influence of straight edge tangential restraints on the nonlinear response of symmetrically laminated and balanced composite cylindrical panels subject to a pinching force is investigated. An 8-node degenerated nonlinear shell element, formulation of which is based on the Total Lagrangian Formulation, is employed for geometrically nonlinear analysis and the Arc-Length Method is used to trace the nonlinear path. First, the element is validated for geometrically non-linear analysis by solving two verification problems. Then, numerical results for different rotational boundary conditions are presented for two different stacking sequences, and thickness values. The numerical results presented show that there is no significant difference between the tangentially unrestrained and restrained clamped panels when only one edge is tangentially unrestrained. However, it is observed that the simply supported panels demonstrate a much less stiff behavior when one of the straight edges is tangentially unrestrained.

Lines under the eyes: a large prospective case series of linear basal cell carcinomas.

Basal cell carcinomas (BCC) are the most common form of cancer globally. Linear BCCs are an unusual variant which are generally defined by having a length three times longer than the width and exhibiting relatively straight edges. In this report, we describe the largest global cohort (n = 31) with this rare subtype. Within this cohort, 22 were in the periocular region, 27 underwent Mohs micrographic surgery and 12 involved oculoplastic reconstruction. These results suggest that, whilst this subtype is relatively rare, it may be more prevalent than previously thought. Dermatologists and other specialities managing skin cancer, particularly ophthalmologists, should, therefore, be aware of this subtype, as it is often more aggressive than other BCC subtypes, often requiring multi-disciplinary management.

Elastodiffusion calculation of asymptotic absorption efficiencies and bias factors of dislocations in Al, Ni and Fe

The elastic interactions between dislocations and lattice point defects (PDs) control the rate of PD elimination at dislocations, and thereby the PD spatial distribution within the microstructure. By relying on the Onsager formalism, we introduce a new partition of the PD diffusion driving force in a strain field. We present DFT-based calculations of straight and loop-form edge dislocation absorption efficiencies and the resulting biases of vacancy and self-interstitial elimination in pure Fe, Ni, and Al metals. We highlight the effects of the dislocation density, the temperature and the dislocation orientation on the elastodiffusion behavior and the resulting PD redistribution near dislocations. Based on a detailed study of the sensitivity of absorption efficiencies to the boundary conditions, i.e., the capture radius and the associated PD concentrations, we introduce the notion of asymptotic absorption efficiencies and bias.

Smoothing topology optimization results using pre-built lookup tables

Topology optimization techniques are typically performed on a design domain discretized with finite element meshes to generate efficient and innovative structural designs. The optimized structural topologies usually exhibit zig-zag boundaries formed from straight element edges. Existing techniques to obtain smooth structural topologies are limited. Most methods are computationally expensive, as they are performed iteratively with topology optimization. Other methods, such as post-processing methods, are applied after topology optimization, but they cannot guarantee to obtain equivalent structural designs, as the volume and geometric features may be changed. This study presents a new method that uses pre-built lookup tables to transform the shape of boundary elements obtained from topology optimization to create smoothed structural topologies. The new method is developed based on the combination of the bi-directional evolutionary structural optimization (BESO) technique and marching geometries to determine structural topologies and lookup tables, respectively. An additional step is used to ensure that the generated result meets a target volume. A variety of 2D and 3D examples are presented to demonstrate the effectiveness of the new method. This research shows that the new method is highly efficient, as it can be directly added to the last step of topology optimization with a low computational cost, and the volume and geometric features can be preserved in smoothed topologies. Finite element models are also created for original and smoothed structural topologies to show that the structural stiffness can be significantly enhanced after smoothing.

Prediction of broadband noise from rotating blade elements with serrated trailing edges

This paper conducts a theoretical investigation into the prediction of broadband trailing-edge noise for rotating serrated blades. Lyu's semi-analytical noise prediction model for isolated flat plates is extended to rotating blades using Schlinker and Amiet's approach and applied to three test applications including a wind turbine, a cooling fan, and an open propeller. The model is validated by comparing the straight edge results with that presented in the work of Sinayoko et al., which shows an excellent agreement. The noise spectra obtained using different-order approximations show that the second-order solution yields a converged result. It is found that trailing-edge serrations can lead to noise reduction in the intermediate- and high-frequency ranges at an observer angle of 45° at low Mach numbers but may lead to noise increase in the intermediate-frequency range at high Mach numbers. The results show that the directivity patterns change due to the use of trailing-edge serrations and the directivity peaks are observed at high frequencies. A detailed analysis on the effects of rotation shows that for low-Mach number applications, the Doppler effect is weak and the peaky directivity pattern is mainly affected by the nonuniform directivity of an isolated flat plate at high frequencies. However, for high-Mach number applications, the Doppler effect is significant and also contributes to the final directivity pattern of rotating blades.

Cell wall fracture mechanism in ultrasonic-assisted cutting of honeycomb materials

Revealing the ultrasonic cutting mechanism of honeycomb composite is important for determining the acoustic parameters of the ultrasonic system and selecting the parameters of the cutting process. Understanding more details of the stress on the cell wall from ultrasonic vibrating tool and the conditions for cell wall breakage is essential to study the machining mechanism. According to the evolution of contact state between the straight edge cutter and the honeycomb cell wall in a cycle, the cutting force acting on the cell wall is divided into three stages: transverse cutting load action, longitudinal cutting load action, and no cutting load action. The cell wall deflection and stress equations under transverse cutting load were established by applying elastic thin plate small deflection theory. The deformation and fracture characteristics of the honeycomb cell wall were analyzed by combining the analytical and the finite element model. The results showed that the ultrasonic vibration of the cutter greatly improved the stiffening effect of the cell wall and its fracture was caused by the deflection under the transverse cutting load, which exceeded the maximum allowable deformation after local stiffening. In addition, with only longitudinal cutting load, it was difficult to break the critical buckling state that leads to cell wall fracture.

Using lifetime of point defects for dislocation bias in bcc Fe

The interaction between dislocations and point defects is key to deformation processes and microstructural evolution of structural materials. In this work, we compute the lifetime of point defects to describe their interaction with dislocations. This approach can accurately account for the effects of the dislocation core and anisotropic defect dynamics to accumulatively determine the capture efficiency, sink strength, and dislocation bias at different temperatures and dislocation densities. Particularly, the absorption of point defects by straight screw and edge dislocations in a model bcc iron system is studied. The maximum swelling rates based on the obtained bias factors are in close agreement with a variety of experimental measurements, including both neutron and ion-irradiation data, especially when considering the survival fraction for point defects from displacement cascades. This approach applies to many other processes and sinks, such as dislocation loops and interfaces, providing a powerful means to develop fundamental insights critical for improving radiation resistance and mechanical properties of structural materials through controlling defect interaction and evolution.

Influence of a Wavy Blade-End Applied in an Axial Compressor Cascade on the Secondary Flow of the Passage

To improve the compressor performances at variable conditions, in this research, we used numerical simulation software to analyze and discuss the effects of three kinks of a wavy blade-end on an axial compressor cascade. One of the wavy blade-ends was a traditional structure with a wavy leading edge and a trailing edge (WBE_P). The other two wavy blades were new structures with a straight trailing edge and a wavy leading edge (WBE_R, WBE_S). The difference between WBE_R and WBE_S was that the blade profile used to form the wavy blade was different. For WBE_R, we obtained the wavy leading edge by rotating the element at different heights, and the trailing edge was the center of a circle. For WBE_S, we obtained the wavy leading edge by using a new element with a different camber angle. Because of the new geometry involving some discussions of a variety of parameters, we further discussed the geometric parameters and structure to guide the design and optimization of the blade. We drew some conclusions at the stable condition (6° incidence). For the first case (WBE_P), when the wavelength of the wavy blade-end was increased to 0.3 times the blade height, the total pressure loss was enhanced. When the wavelength was 0.2 times the blade height, the amplitude was 0.06 times the pitch, the minimum area of blocked range (Ab) and the total pressure loss coefficient ζ could be obtained, and the ζ and Ab were decreased by 5.49%, and 12.72% compared with the baseline. Furthermore, to weaken the influence of changed blade profile on the exit airflow angle, we proposed WBE_P and WBE_R with new structures. We further improved the flow-field characteristics of WBE_P by WBE_R, and the ζ and Ab decreased by 5.84% and 13.79% compared with the baseline. Additionally, the stall point was delayed from 7.5° to 7.7° incidence. Therefore, the wavy blade-end applied in the leading edge had a greater contribution to improving the flow characteristic, and the straight trailing edge was beneficial to maintaining the exit flow angle. WBE_S with a smoother blade surface did not show an advantage compared with WBE_R. WBE_R with a wavy blade-end leading edge and a straight trailing edge showed an advantage in improving the cascade performance, which was suitable for use in the stator from the last stage of a high-load axial compressor.

Event-Based Line SLAM in Real-Time

Event-based cameras generate asynchronous streams of events, triggered proportionally to the logarithmic change of brightness in the scene. These cameras have very low latency and high dynamic range suitable to address challenging motion scenarios in robotics. In this work, we explore a new event-based line-SLAM approach following a parallel tracking and mapping philosophy. Our fast tracking algorithm, produces accurate camera pose estimates at a high rate by minimizing the event-line reprojection error with an error-state Kalman filter formulated entirely with Lie theory. The mapping thread leverages the natural edge highlighting strength of events to recover and optimize straight lines in human-made scenarios. The proper manipulation of matrix sparsity as well as the information sharing between tracking and mapping nodes allow us to achieve real-time performance on a standard multi-core CPU. This system was tested on several scenarios rich in straight edge objects, and compared against, ground truth and frame and event based state-of-the-art approaches.

A Broadband Circularly Polarized Endfire Loop Antenna for Millimeter-Wave Applications

In this letter, a broadband circularly polarized (CP) endfire loop antenna is proposed for millimeter-wave (mmW) applications. The loop consists of two arms constructed by printed strips with straight edge connections implemented by metalized via-holes, and is fed by substrate integrated waveguide differentially. The quasi-traveling wave currents flowing along strips and via-holes, which generate horizontal and vertical polarizations, respectively. By using the offset strip, comparable amplitudes of two polarizations are realized to achieve a good CP radiation. Furthermore, a dielectric rod is applied for higher gain. The experimental prototype reported that the impedance bandwidth of 28.3% from 23.75 to 31.4 GHz, the 3 dB axial-ratio bandwidth of 25% from 24.25 to 31 GHz, and the gain no less than 9 dBic for endfire radiation. In addition, the whole antenna is curved on one substrate with a low profile of 0.14 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free-space wavelength at 27 GHz). Thus, the antenna is attractive for fifth-generation (5G) applications in mmW integrated circuits.

Features of solving the problem of condensation of vapor containing solid particles on the edge

THE PURPOSE. To evaluate the effect on the condensation process of contaminants contained in the steam and deposited on the surface of the cooled fins, for which to formulate a mathematical model of the process, to investigate its properties and to obtain quantitative estimates of the characteristics.METHODS. The equations of the mathematical model are based on the laws of conservation of energy and mass, their study and evaluation are carried out using analytical methods of the theory of differential equations, methods of similarity theory and dimensions, as well as numerical methods for solving boundary value problems.RESULTS. The formulation of the problem of condensation of vapor containing solid particles on the edge is formulated. The presence of a self-similar solution is revealed, which is represented as a dimensionless function of one variable, uniform for all sets of initial parameters. The relations describing the distributions of the thickness δ(x, τ) of the sediment and the temperature ϑ(x, τ) on a straight edge of unlimited height (l = ∞) with an initially clean surface (h0 = 0) are obtained. These relations also almost accurately describe the initial stage of such a process on a straight edge of a finite height l, until a sediment of noticeable thickness covers the entire surface of the rib, as well as the initial moments in the case of an edge on a round pipe, until the width of the sediment zone with a noticeable thickness is significantly less than the radius of the pipe.CONCLUSION. Using these distributions as the initial ones for edges of limited height instead of, for example, introducing a uniform initial layer h0, will allow achieving high accuracy of numerical calculations without excessive thickening of the grid in coordinate and time.

Lensless light intensity model for quasi-spherical cell size measurement.

Quasi-spherical cell size measurement plays an important role in medical test. Traditional methods such as a microscope and a flow cytometer are either it depends on professionals and cannot be automated, or it is expensive and bulky, which are not suitable for point-of-care test. Lab-on-a-chip technology using the lensless imaging system gives a good solution for obtaining the quasi-spherical cell size. The diffraction effects and the low resolution are the two main problems faced by the lensless imaging system. In this paper, a lensless light intensity model for the quasi-spherical cell size measurement is given. First, the diffraction characteristics of a quasi-spherical cell edge are given. Then, a diffraction model at an arc edge is constructed based on the Fresnel diffraction at a straight edge. Using the diffraction model at an arc edge, we explained the mechanism of the formation of the quasi-spherical cell diffraction fringes. Finally, the light intensity of the first bright ring of the quasi-spherical cell diffraction pattern is used to achieve quasi-spherical cell size measurement. The required equipment and the measurement methods are extremely simple, very suitable for point-of-care test. The experimental results show that the proposed model can realize the statistical measurement of the quasi-spherical cells and the classification of the quasi-spherical cells with a difference of 1 [Formula: see text].

Edge imaging characteristics of aberrated coherent optical systems by edge masking of circular apertures

In this paper, attempts have been made to study the joint effects of apodization and aperture masking on the diffraction images of coherently illuminated straight edge. The Edge-Ringing, Edge-Shift and Edge-Eradient of the edge images have been evaluated for different values of apo-dization using edge masking of circular apertures. We have considered rotationally symmetric, ab-errated coherent optical system. These investigations have lead to the use of certain pupil functions in conjunction with optimal apodizers to assess the quality of edge images. Any obstruction placed in the light path of an optical system prevents waves from a portion of the wavefront in reaching the focal zone. This results in the change in the light flux at every point of the diffraction pattern. This is in turn, depends on the shape and size of the obstruction.

Thermal characterization of straight and curve edge blade liquid fuel swirl burner

Accurate monitoring and controlling of the temperature in the combustion chamber can raise the burner efficiency, combustion intensity, fuel consumption and reduce pollutant emission. However, except combustion is accurately monitored and controlled, high concentration of pollutant gases and products like carbon monoxide (CO) and soot can form in the combustion chamber. This paper compares the combustion thermal profiles in a liquid fuel swirl burner using developed straight edge and curve edge blade swirlers at (20, 30, 40, 50 and 60)° for 6, 8, 10 and 12 number of blades in order to optimize the temperature of the burner. Measurements were made in straight and curve blades liquid fuel swirl burner in order to study and compare the thermal characteristics of the straight and curve edge blades in optimizing the combustion dynamics. Similarly, measurements were made for burner without swirl generator and the combustion temperature assessed. Thermal profile was measured in the direction of flow via the six axial ports at distance ((d) =150, 350, 550, 750, 950 and 1150 mm) from the burner exit using Chromium-Zinc thermocouple. Results showed that the wavelength and oscillation of temperature decay in the same type of blade followed the same trend and the peak of combustion intensity is nearer the nozzle for curve edge blades than the straight edge blade. Six (6) blades performed best with the highest temperature in all the ports, while 12 blades gave the least performance. Findings further show that curve edge blade swirlers gave better performance than straight edge blade swirlers with highest temperature of (1065 and 1015) °C, respectively. Hence, it is recommended especially where high temperature and stability application is desirable

A novel monotone finite volume element scheme for diffusion equations

We present a novel monotone finite volume element scheme for the diffusion problem on triangular grids. Firstly, one fictitious triangular element is introduced for each edge of any element, and another vertex of this fictitious element is on the outward extended straight line passing through two points: The vertex opposite to this edge and the barycenter of the element. The diffusive tensor and the solution in this element are continuously extended to its corresponding fictitious element. The fictitious element and the continuous extension not only avoid the phenomenon that the control volume segment passes through other elements, but also are helpful to the construction and theoretical analysis for our monotone scheme. Secondly, one new nonlinear two-point flux formulation is obtained for some part control volume edge whose another endpoint is the barycenter of the fictitious element, and this straight segment crosses through the common edge of the triangular element and its fictitious one. The approximation of κ∇u on this straight control volume edge is constructed by some weighted average with the gradients of two finite element functions, and the weighted coefficients are determined by the nonlinear two-point flux idea. Furthermore, we proved that the new scheme is monotone under some conditions: the diffusion tensor and exact solution functions are properly smooth, and the partition step size h is properly small, and the solutions on three nodes of any element are not nonnegative, and furthermore not simultaneously zero, and the nodes of the fictitious element are properly chosen. We also proved that the corresponding coefficient matrix is of M-matrix. Finally, we carry on some typical experiments. Numerical results verify the monotonicity of this new scheme, and confirm its accuracy and stability.

The separation angle of the free surface of a viscous fluid at a straight edge

We rework some of the die-swell singularity analysis for Stokes flow, originally by Ramalingam (Ramalingam, 1994 Fiber spinning and rheology of liquid-crystalline polymers, PhD thesis, Massachusetts Institute of Technology) in appendix A of his PhD thesis, in an attempt to demonstrate that for capillary numbers in the range $(0,\infty )$ the curvature may enter into the normal stress balance on the free surface and lead to separation angles exceeding $180^{\circ }$ and infinite curvature at the separation point. The singular coefficients in the asymptotic solution and the free surface shape in a neighbourhood of the separation point cannot be determined by a local analysis of the Michael type (Michael, Mathematika, vol. 5, 1958, pp. 82–84) but must be found from matching with the solution valid away from the die edge. The numerical method that we use in the truncated die-swell domain is a boundary element method incorporating the singular solution near the separation point. Although there is some variation in the extrudate swell ratios at different capillary numbers reported in the numerical literature, our results for capillary numbers $Ca$ from $1$ to $1000$ are within the range of values published in earlier papers. The computed separation angles at different values of $Ca$ agree well with the range of separation angles to be found in experimental and numerical papers. The separation angle appears to converge to a value different from $180^{\circ }$ as $Ca$ increases, leading us to conclude that the case of zero surface tension ( $Ca=\infty$ , with corresponding separation angle of $180^{\circ }$ ), is a singular limit.