Straight Part Research Articles

Endothelial Cell Morphology Regulates Inflammatory Cells Through MicroRNA Transferred by Extracellular Vesicles.

Vascular inflammation plays an important role in the pathogenesis and the development of cardiovascular diseases such as arteriosclerosis and restenosis, and the dysfunction of endothelial cells (ECs) may result in the activation of monocytes and other inflammatory cells. ECs exhibit an elongated morphology in the straight part of arteries but a cobblestone shape near the pro-atherogenic region such as branch bifurcation. Although the effects of hemodynamic forces on ECs have been widely studied, it is not clear whether the EC morphology affects its own function and thus the inflammatory response of monocytes. Here we showed that elongated ECs cultured on poly-(dimethyl siloxane) membrane surface with microgrooves significantly suppressed the activation of the monocytes in co-culture, in comparison to ECs with a cobblestone shape. The transfer of EC-conditioned medium to monocytes had the same effect, suggesting that soluble factors were involved in EC–monocyte communication. Further investigation demonstrated that elongated ECs upregulated the expression of anti-inflammatory microRNAs, especially miR-10a. Moreover, miR-10a was found in the extracellular vesicles (EVs) released by ECs and transferred to monocytes, and the inhibition of EV secretion from ECs repressed the upregulation of miR-10a. Consistently, the inhibition of miR-10a expression in ECs reduced their anti-inflammatory effect on monocytes. These results reveal that the EC morphology can regulate inflammatory response through EVs, which provides a basis for the design and the optimization of biomaterials for vascular tissue engineering.

State Observability through Prior Knowledge: Analysis of the Height Map Prior for Track Cycling.

Inertial navigation systems suffer from unbounded errors in the position and orientation estimates. This drift can be corrected by applying prior knowledge, instead of using exteroceptive sensors. We want to show that the use of prior knowledge can yield full observability of the position and orientation. A previous study showed that track cyclers can be tracked drift-free with an IMU as the only sensor and the knowledge that the bike drives on the track. In this paper, we analyze the observability of the pose in the experiment we conducted. Furthermore, we improve the pose estimation of the previous study. The observability is analyzed by testing the weak observability criterion with a Jacobian rank test. The improved estimator is presented and evaluated on a dataset with three 60-round trials (10 km each). The average RMS is 1.08 m and the estimate is drift-free. The observability analysis reveals that the system can gain complete observability in the curves and observability of the orientation on the straight parts of the race track.

Effect of clamped beam pattern on resonant frequency shift of microresonator under near-infrared laser irradiation

In this study, we investigated the effect of the resonator beam shape on the thermal stress and the resonance frequency change when providing heat to the resonator beam by near-infrared laser irradiation. This investigation provides crucial data for optical and heat sensing application using microresonators. The microresonator beam with an optical absorber for near-infrared region was fabricated, varying the numbers of beams and corners. When irradiating the optical absorber with a laser, the resonant frequency decreased. It is because the photothermal effect provides compressive stress in the beam, resulting in resonant frequency decrease. The resonant frequency change rate increased with decreasing the number of beams. According to the analytical results, we confirmed that the analytical thermal stress determined the resonant frequency change rate in the same beam length. The corner remarkably decreased the resonant frequency change rate. The straight beams bend to the orthogonal direction by the thermal expansion of another straight part of the beam, resulting in deformation of the beam in the axial direction. Therefore, the reaction force and compressive stress in the axial direction reduces.

CFD modeling of black powder particles deposition in 3D 90-degree bend of natural gas pipelines

Black powder deposition is the common problem in the natural gas transmission networks that occurs in some parts of the pipelines, especially in the bends. In this work, the flow of natural gas-particles was simulated within the Eulerian-Lagrangian framework in an industrial 90-degree bend based on the 3D computational fluid dynamics (CFD) tool. The shear stress turbulence (SST) model was applied to simulate the fully developed turbulent gas flow. The size range of the black powder particles was considered within 1–100 μm with Stokes number (Stk) in the range of 0.001–11.25 to include the low and high inertia particles. The results showed that the penetration efficiency of the smaller black powder particles is higher than larger ones and follow the flow streamlines easily without significant deposition on the inner walls. In addition, the particle penetration efficiency in the bend curvature, is considerably less than other straight parts of the pipe, revealing that the particle deposition occurs significantly in those region. It was also observed that the penetration parameter is independent of the number of black powder particles. The effects of the natural gas flow velocity and pipe diameter size on the particle deposition were also investigated. According to the obtained results, increasing the gas flow velocity leads to a decrease in the particles penetration efficiency, consequently increase the particle deposition. The accuracy of the model verified via some available particle deposition data in the literature.

Unidirectional anisotropy in bent ferromagnetic microwires

New measurements are described on hysteresis loops of bent amorphous Fe-based microscopic wires. In our setup, a wire consists of a straight part along which the longitudinal field is applied, and other straight parts, one or two, which are perpendicular to the applied field. The magnetization of these other parts does not change during the hysteresis experiment. The observed switching field depends on the spatial configuration of the wire. In particular, unidirectional anisotropy is detected, which is visible as a reduction of the switching field for ascending or descending direction of changes of the applied field. The results are explained in terms of pseudodipolar interaction of the wire parts. We also demonstrate that anisotropy of the same sign is produced by the Dzyaloshinskii-Moriya interaction.

Analysis and Optimization of Staggered Partial Diffuser Vanes in a Centrifugal Pump

Abstract A performance analysis and three-objective design optimization were performed for the staggered partial diffuser vanes in a centrifugal pump using three-dimensional Reynolds-averaged Navier–Stokes equations. First, the performance of the diffuser vanes was evaluated for four different arrangements: full-height diffuser vanes, vaneless diffuser, half vanes attached to the hub, half vanes attached to the shroud, and staggered vanes attached alternately to the hub and the shroud. The staggered partial diffuser vanes were optimized using the following design variables: the installation angle of the vanes, the heights of the vanes attached to the hub and shroud, and the angle of rotation of the straight part on the pressure surface of the vanes. The objective functions were the hydraulic efficiency, the flowrate of the maximum pressure recovery, and the operating range of the diffuser. The Kriging model was used to construct surrogate models of the objective functions based on the results at the design points obtained by Latin hypercube sampling. The Pareto-optimal solutions were obtained by a multi-objective genetic algorithm (MOGA). The representative Pareto-optimal solutions for the staggered diffuser vanes obtained by the K-means clustering showed the improved performances in terms of both the hydraulic performance and operating range compared with the full-height diffuser vanes and the baseline design.

Track gauge measurement based on wheel-rail lateral relative displacement

Aiming at the complexity of the traditional gauge detection method, high requirements for the installation and large amount of data analysis, a gauge measurement method based on the relative transverse movement of wheel and rail is designed in this paper. Two sets of laser source and camera combinations are used to dynamically collect the image of the inner straight line part of the rail head in the method. According to the rail parameters, the Hough detection and perspective transformation are used to rectify the image from the same acquisition distance. Compared to datum moment, the variation of vertical displacement of the center point of the laser is computed. And through the geometrical relation of the variation previously described and the lateral relative displacements of the two wheels, the relative transverse displacement of the two wheels is calculated. The relative initial time gauge change is gained by the difference, which realizes the indirect measurement of the track gauge. The experimental results show that the method has the characteristics of simple hardware structure, small data calculation, high measurement precision, and can realize non-contact dynamic measurement of gauge parameters.

Behaviour Analysis of Reinforced Soil Retaining Wall According to Laboratory Scale Test

Reinforced soil retaining wall are ground structures that can be readily seen all around us. The development of reinforcements to these walls and their demand have increased rapidly. These walls are advantageous because they can be used not only in simple construction compared with reinforced concrete retaining walls but also when the height of the wall needs to be higher. However, unlike reinforced concrete retaining walls, in which the walls are integrated and resist the earth pressure on the back, the block-type reinforced earth retaining wall method secures its structural stability by frictional force between the buried land and reinforcements. A phenomenon in which a block is cracked or dropped owing to deformation has been frequently reported. In particular, this phenomenon is concentrated at the curved parts of a reinforced soil retaining wall and is mainly known as a stress concentration. However, to date, the design of reinforced soil retaining walls has been limited by the two-dimensional plane strain condition and has not considered the characteristics of the curved part. There is a lack of research on curved part. Therefore, this research determines the behavioural characteristics of curved-part reinforced soil retaining walls with regard to the shape (convex or concave) and angle (60°, 90°, 120°, and 150°). The displacement generated in the straight part and the curved part was analysed through an Laboratory Scale Test. The results showed that the horizontal displacement of the curved part increases as a convex angle becomes smaller, and the horizontal displacement of the curved part decreases as a concave angle becomes smaller. At the center (D and H have the same length, but H represents the height and D represents the separation distance from the center of the curved part) of the convex curve, the horizontal displacement of the 0.5 D section decreased to 13.8%; it decreased to 41.0% in the 1.0 D section. For concave angles, it was revealed that the horizontal displacement from the center 0.0 D to the 0.5 D section of the curved part increased by 25%, and from the 1.0 D section, by 75%. It was confirmed that the displacement difference was largely based on the value of 0.5 D. It was judged that this can be used as basic data for the design and construction guidelines for reinforced soil retaining wall of reinforced soil retaining walls.

Investigating the Effect of Weight Reduction of Rod-End in Drag-Link Product with Finite Element Analysis, Fatigue Test, and a Case Study

The connection surfaces of drag-link must be tough and safe enough to carry transmitted forces that exert on the product in service conditions. Therefore, undulated forming takes place in machining process to stay the rod-ends in the rod. In the rod-end, after forming process, a straight part which remains on the body causes extra cost and weight on the product. In this study, the result of shortening of rod-end which was produced from C45+N quality steel was investigated by comparing with the unmodified rod-end. The comparison was carried out by fatigue test and Finite Element Analysis. The results showed that the cropped part has almost no effect on the durability of the product. It is measured that the modification result with 0,082 kg weight reduction on each rod-end and 5 seconds shortening of machining process were observed by the modification on rod-end. The effect of modification on the part was examined in a case study. The case study indicated that annual expenses of raw material lowered by $9.124,56 and total cost decreased by $11.480,20.

Numerical prediction of ductile fracture in multi-stage single point incremental forming based on phenomenological modified Mohr–Coulomb

Since the conventional simulation for multi-stage single point incremental forming cannot describe the phenomenon of ductile fracture of material, the suitability of a deformation strategy is not evaluated. Therefore, the numerical prediction of ductile fracture is especially significant for the application and development of MSSPIF. In this paper, the calculation of forming stages and the evaluation criteria of ductile fracture are separately established to design intermediate profiles and to estimate initial crack of material for MSSPIF of straight wall parts based on phenomenological modified Mohr–Coulomb. Moreover, the effect of some factors (stress triaxiality, normalized Lode angle, and forming stage) on ductile fracture is analyzed in detail, and then a high-precision finite element model coupled MMC3 is established to predict the ductile fracture of material during MSSPIF. Meanwhile, the fracture forming limit diagram for MSSPIF is also obtained and higher than that obtained by single-stage single point incremental forming.

New possibilities of worm thread machining and practice of implementation

Thread grinding is the traditional operation of final machining for worms and other critical threads. However, similar to other types of tooth grinding, this type of machining is expensive; it requires application of high cost equipment and needs valuable workers. In many practical cases, its alternative can be the application of edge machining, especially as the possibilities of controlling the corresponding advanced machine-tools and their accuracy have been increased significantly. This paper describes the experience of implementation of edge machining of worm threads within a low-series production of spiroid and worm gearboxes for pipeline valves gained at the Institute of Mechanics named after prof. V.I. Goldfarb of Kalashnikov Izhevsk State Technical University and at the Small Innovative Enterprise “Mechanik”. Schemes of thread machining by straight and radial parts of a single cutter and by a face cutter head are considered. The technique is implemented, and it provides the reduction of labor intensity and prime cost of both the preliminary and final machining of worms, including heat-strengthened ones; and it also results in the correctly localized contact in worm and spiroid gears.

Investigations into the influence of tool helix angle during end milling of open straight and curved thin-wall parts

In this paper, the influence of cutting tool helix angle on performance parameters viz., milling force, part deflection, surface finish, chip morphology and micro-hardness considering open straight and curvilinear thin-walled parts is analysed. It was found that end mills with helix angle of 45° and 55° helped in achieving good surface finish and form accuracy while machining thin-wall parts. During machining, parts having concave geometry due to its inherent rigidity, generated higher milling force. But the wall deflection and form error was relatively lower in comparison with the straight wall thereby resulting in better surface finish. Also, formation of built-up-edge (BUE) at the cutting edge of end mills having 35° helix was noted which aided in surface defects. Back surface of the chips machined using 35° tools showed prominent lamella like structures but tools having higher helix angles were found to produce relatively lamella free surface.

Investigations into the influence of tool helix angle during end milling of open straight and curved thin-wall parts

In this paper, the influence of cutting tool helix angle on performance parameters viz., milling force, part deflection, surface finish, chip morphology and micro-hardness considering open straight and curvilinear thin-walled parts is analysed. It was found that end mills with helix angle of 45° and 55° helped in achieving good surface finish and form accuracy while machining thin-wall parts. During machining, parts having concave geometry due to its inherent rigidity, generated higher milling force. But the wall deflection and form error was relatively lower in comparison with the straight wall thereby resulting in better surface finish. Also, formation of built-up-edge (BUE) at the cutting edge of end mills having 35° helix was noted which aided in surface defects. Back surface of the chips machined using 35° tools showed prominent lamella like structures but tools having higher helix angles were found to produce relatively lamella free surface.

АНАЛИЗ ЭФФЕКТИВНОСТИ ПРИМЕНЕНИЯ БОМБИНИРОВАННЫХ РОЛИКОВ ДЛЯ СНИЖЕНИЯ КОНТАКТНЫХ НАПРЯЖЕНИЙ В РОЛИКОПОДШИПНИКЕ

The main problem of using roller bearings with direct forming rolling elements in highly loaded units is the edge effect. A significant increase of stresses at the edges of the rolling elements is the cause of the fragility of highly loaded roller bearings, which is a significant problem, especially in such units as rotors of aircraft engines. The solution of this problem in aviation is the use of rolling elements with a modified contact - bombed rollers. This paper presents comparisons of the stress-strain state of contacts of pairs of bodies imitating bombarded rollers of various geometries. The calculation was performed by the finite element method in the ANSYS package. For the calculation, the contact of the roller with a flat plate was used. In the calculation, the stress-strain state of the roller with the direct forming, the roller with the rounding of the face and the bombed rollers with various shapes of the modified forming was evaluated. The calculation model is verified with respect to the classical Hertz formula. The dependence of stresses in the concentration zone on the relative dimensions of the bombarded part of the roller with a standard generator representing an arc of a circle is estimated. A form of the generatrix is proposed, which more effectively reduces stresses in the transition zone of the modified generatrix into the straight line. The proposed form of the generatrix eliminates the main drawback of the classical generatrix of the bombarded rollers - the appearance of a concentration zone in the transition region of the straight part of the roller to the bombed, thus providing a better stress distribution in the roller. The technique used to simulate the contact interaction of rolling elements in a roller bearing can be used to study the stress-strain state of roller bearings of a different geometry, including those used in modern gas turbine engines.

Optimization of the longitudinal-torsional ultrasonic step-like horn design for milling tool applications via the tool load account

Ultrasonic horns are used in the ultrasonic-assisted milling and cutting tools. However, the interaction with tool end vibrations deteriorates the horn performance. In this study, the amplification coefficients and vibration node locations of an ultrasonic horn were determined via the 1D wave theory and optimized by the tool load effect account. By arranging spiral grooves at the straight part of the ultrasonic horn, a longitudinal-torsional modal converter was introduced. This made it possible to convert longitudinal vibrations into longitudinal-torsional coupled ones by the superposition of incident and reflected longitudinal waves with reflected transverse ones at grooves. Orthogonal L9 (33) tests with parameters of spiral grooves as variables were designed and conducted, and longitudinal-torsional ratios (LTR) of the milling tool end under different conditions were assessed using the commercial ANSYS software package. The in-depth analysis of simulation results implies that the LTR values are controlled by the following influence factors in the decreasing order: helical angle, number of grooves, and groove width. Single-factor tests indicate that LTR exhibits an initial drop and a further rise with the helical angle, attaining its minimal value at 30°; it drops with the number of grooves n, and remains practically unchanged with the groove width variation. Finally, the vibration tests of the proposed horn with the optimized parameters corroborated its feasibility and demonstrated its excellent performance in the ultrasonic-assisted milling tool application.

Concept of an Evaluation Technique for Planar Elongational Stress and Relaxation Time Using Hoop Stress in Swirling Flow

The paper reports a novel idea of an experimental approach to estimate the apparent planar elongational viscosity and the relaxation time of low viscosity fluids. A two-dimensional swirling contraction channel is designed to maintain a constant elongation rate to the flow direction. The hydrodynamic focusing creates a stable planar elongation flow field. The flow is injected into the center of the channel and a sheath flow is injected through both sides. The sample fluid is stretched in the flow field, and then forms the ribbon-shaped filament. In the swirling contraction part, a static force balance between the hoop force caused by the planar elongational stress and the centrifugal force determines the radial position of the filament. The distribution of the planar elongational stress can be estimated by observing this position, and then the apparent planar elongational viscosity was calculated using developed simplified expressions. On the other hand, when a channel with a constant width swirling part is used, the elongational stress generated in the straight contraction part gradually decreases passing through the constant width part. The sample filament position is then shifted based on the stress relaxation. The relaxation time can be evaluated by observing this variation.

A Novel Smart Energy Management System in Pure Electric Motorcycle Using COA

Todays, Greenhouse Gases (GHG) emissions, densely populated urban areas air quality problems, and depleting fossil fuel concerns motivated motorcycle producers in crowded countries to explore electric propulsion systems. Due to energy storage system constraints, Pure Electric Motorcycles (PEM) range is restricted, so an effective Energy Management System is required to optimize PEM consumed energy. As road curvature is an inevitable part of real roads, this article, proposes a novel Smart Energy Management System (SEMS) based on road geometry which first analyses road data to identify curvature and straight parts. Then, SEMS solves optimization problems separately and optimal speed is calculated in direct and curvature parts independently. The proposed SEMS can communicate to the driver as an eco-driving system by receiving trip time importance and presenting each road point optimal speed. Because of fast response necessity, Cuckoo Optimization Algorithm (COA) is used in this article to solve SEMS optimization problem. For evaluation purposes, three scenarios are defined: The test road is travelled at motorcycle maximum allowable speed in the first scenario. In the 2nd one, PEM speed is also constant but it equals to direct road optimal speed instead of max. speed. Independent optimal speed in direct and curvature parts is considered in 3rd scenario. Simulation results show the significant effect of road curves on consumed energy and SEMS good performance in optimization of PEM consumed energy.

Influences of deposition strategies on thermo-mechanical characteristics of a multilayer part deposited by a wire feeding type DED process

Variation in process parameters and deposition strategies has produced different thermo-mechanical characteristics in a part fabricated by a wire feeding type directed energy deposition (DED) process. The purpose of this paper is to select a proper deposition strategy to fabricate a straight wall part using a wire feeding type DED process. The deposition strategies include different deposition directions, deposition patterns and interpass time. In order to investigate the influences of deposition strategies on thermo-mechanical characteristics of fabricated part, three-dimensional finite element analyses (FEAs) have been proposed. A volumetric heat flux has been applied to simulate the transient heat transfer phenomena of the DED process. Influences of different deposition strategies on thermo-mechanical characteristics of fabricated part have been discussed. From the result of residual stress distribution, an appropriate deposition strategy has been selected for the multi-layer deposition. Results of FEAs have been verified through comparison of vertical displacements between estimated results from FEAs and those of experiments.

Longitudinal Guided Wave Inspection of Small-Diameter Elbowed Steel Tubes with a Novel Squirrel-Cage Magnetostrictive Sensor

In the study, ultrasonic longitudinal mode guided waves were employed to detect defects in elbowed tubes (without welds) with a diameter of 10 mm. Finite element simulation results highlighted that the emitted L(0,1) mode guided waves experienced strong reflection and mode conversion at the elbow region to generate F(1,1) mode, followed by slow and weak F(2,1) mode. The guided wave reflected from the elbow with a through-wall defect was manifested as two overlapped wave packets, which were good indicators of a defective elbow. To conduct L(0,1) mode guided waves inspection on the small-diameter elbowed tubes, a novel tailored squirrel-cage magnetostrictive sensor was employed in the experiment. The new sensor employed the configuration of segmental iron-cobalt strips and small-size permanent magnet arrays. The entire sensor is composed of two identical C-shaped sensor elements and can be recycled and installed conveniently. Experimental results obtained from healthy and defective tubes were consistent with the conclusions obtained from finite element simulations. An artificial through-wall defect at the elbow and a notch defect at the straight part of the tube could be simultaneously detected by L(0,1) mode guided waves through comparing experimental signals with simulation results.

Dispersion Process in Sewer Pipes with Sediments and Deposits

This paper describes the dispersion process in sewer pipes, which is from the hydraulic point of view a prismatic stream channel with relatively constant roughness of streambed. In such hydraulic conditions should the effect of “dead zones” not occur, but this effect was observed during the field experiments. The reason for this was the presence of bed sediments and deposits, which form together with other small obstacles irregularities in the sewer pipe such dead zones. Dead zones are areas with small flow velocities, which act as a zone with transient (temporary) storage, where the pollution is accumulated and released gradually later. This process modifies the dispersion process in sewer systems and causes irregularities in the transport process. Field experiments were performed in a straight sewer section and also in the part with directional changes of sewer line, both under dry weather flow conditions, i.e. with relatively low pipe filling, discharges and velocities. Sewer pipes had a low slope, so a lot of deposits and sediments were present. Paper presents the results of field experiments and analyse the impacts of sediments and deposits in sewer system on the transport and dispersion process, which is reflected in the value of dispersion coefficient. In the case of sewer pipelines, the most important is the longitudinal dispersion coefficient DL. Comparing the values of DL in the straight part and in the part with directional changes, DL values in the straight part were higher than from the section with directional changes. The maximal value of the dimensionless longitudinal dispersion coefficient p reached 25.2 in a straight section; in the part with the directional changes p it was up to 39.3. This result indicates that in the straight part of the sewer line, the longitudinal dispersion of the substance is dominant in the total dispersion process, whereas in the sewer part with directional changes, the transversal (lateral) dispersion contributes to the whole mixing process (dispersion process is also influenced by the velocity gradient in the transverse direction). Within the measured channel section, there were three directional changes - angles of 90°, 135° and 105°. The influence of the direction change angle to the longitudinal dispersion coefficient within the performed measurements has not been clearly determined yet.