Trapezoidal Cross-section Research Articles

3D-Stacked Multistage Inertial Microfluidic Chip for High-Throughput Enrichment of Circulating Tumor Cells.

Whether for cancer diagnosis or single-cell analysis, it remains a major challenge to isolate the target sample cells from a large background cell for high-efficiency downstream detection and analysis in an integrated chip. Therefore, in this paper, we propose a 3D-stacked multistage inertial microfluidic sorting chip for high-throughput enrichment of circulating tumor cells (CTCs) and convenient downstream analysis. In this chip, the first stage is a spiral channel with a trapezoidal cross-section, which has better separation performance than a spiral channel with a rectangular cross-section. The second and third stages adopt symmetrical square serpentine channels with different rectangular cross-section widths for further separation and enrichment of sample cells reducing the outlet flow rate for easier downstream detection and analysis. The multistage channel can separate 5 μm and 15 μm particles with a separation efficiency of 92.37% and purity of 98.10% at a high inlet flow rate of 1.3 mL/min. Meanwhile, it can separate tumor cells (SW480, A549, and Caki-1) from massive red blood cells (RBCs) with a separation efficiency of >80%, separation purity of >90%, and a concentration fold of ~20. The proposed work is aimed at providing a high-throughput sample processing system that can be easily integrated with flowing sample detection methods for rapid CTC analysis.

Deflection behavior of sandwich panel with corrugated core of trapezoidal cross section

Deflection behavior of sandwich panel with corrugated core of trapezoidal cross section

Giardia purification from fecal samples using rigid spiral inertial microfluidics

Giardia is one of the most common waterborne pathogens causing around 200 × 106 diarrheal infections annually. It is of great interest to microbiological research as it is among the oldest known eukaryotic cells. Purifying Giardia from fecal samples for both research and diagnostic purposes presents one of the most difficult challenges. Traditional purification methods rely on density gradient centrifugation, membrane-based filtration, and sedimentation methods, which suffer from low recovery rates, high costs, and poor efficiency. Here, we report on the use of microfluidics to purify Giardia cysts from mouse feces. We propose a rigid spiral microfluidic device with a trapezoidal cross section to effectively separate Giardia from surrounding debris. Our characterizations reveal that the recovery rate is concentration-dependent, and our proposed device can achieve recovery rates as high as 75% with 0.75 ml/min throughput. Moreover, this device can purify Giardia from extremely turbid samples to a level where cysts are visually distinguishable with just one round of purification. This highly scalable and versatile 3D printed microfluidic device is then capable of further purifying or enhancing the recovery rate of the samples by recirculation. This device also has the potential to purify other gastrointestinal pathogens of similar size, and throughput can be significantly increased by parallelization.

ペンギンの体表を模倣したリブレットの3次元胴体モデルにおける抗力低減効果

Penguins have adapted to underwater swimming in the course of evolution. Previous study showed that the riblets mimicking the body feathers of the penguins reduced drag on a flat plate by up to 2.0%. In this study, we measured drag reduction rate of the penguin-mimetic riblets on a 3D body model. Based on a sideview image of a swimming penguin, a 3D spindle model of which cross section was a regular 24-gon shape was created. Riblets were fabricated on flexible polyimide films by laser scanning ablation so that the riblet films were attached to the curved surfaces. Two different cross sections of the riblets were compared: one was the penguin-mimetic trapezoidal cross section (medium-ridge riblet), and the other was a near-rectangular cross section (wide-ridge riblet). Drag of the 3D bodies covered with films with or without riblets was measured in a water channel. As a result, the maximum drag reduction rate of the medium-ridge riblet for the 3D body was 3.5% when s+ was 7.29, which was higher than the drag reduction rate for the flat plate with similar s+ (0.58% with s+ of 7.23) or the maximum value (0.60% with s+ of 10.4). Moreover, the medium-ridge riblet showed higher drag reduction ratio than the wide-ridge riblet for full range of flow speed in this study. The results suggest that the penguin-feather-mimetic riblet reduces not only frictional drag but also pressure drag for the 3D body.

Research on the influence of different obstacle structures on the energy distribution characteristics of pulse detonation gas

In order to improve the gas energy conversion efficiency at the outlet of the pulse detonation combustor, numerical calculation methods were used to study the influence of three different cross-section obstacle structures of square, circle and trapezoid on the distribution characteristics of gas pressure potential energy, kinetic energy and internal energy in a single cycle at the outlet of pulse detonation combustor. The results show that: the expansion of pulse detonation gas mainly includes three-stages: primary expansion, secondary expansion, and over-expansion. Gas pressure potential energy, kinetic energy, and internal energy increase during the primary and secondary expansion stages, and decrease during the over-expansion stage. Pulse detonation combustor with trapezoidal cross-section obstacle structure has the smallest proportion of gas energy at the outlet of the combustor during the over-expansion stage and the highest proportion during the secondary expansion stage. Compared with square and circle cross-section obstacle structures, the gas energy distribution at the outlet of the pulse detonation combustor with trapezoidal cross-section obstacle structure is the easiest for turbomachinery to convert the gas energy.

Experimental Study on Flow and Heat Transfer Characteristics in the Circular-Arc-Shaped Flow Channel

Different parameters of the circular-arc, trapezoidal and equal cross-section-shaped flow channels were analyzed, and the core volume goodness factor was used for the comparison of the three different types of flow channels. During the experiment, the Reynolds number (Re) on the air side ranged from 1200 to 5100. The results showed that the overall heat transfer performance of the three channels in this paper are circular-arc, trapezoidal and equal cross-section in order from good to bad. The overall heat transfer enhancement performance of the circular-arc flow channel is the best, which is 9–26.2% and 3.6–11.8% higher than that of the equal and trapezoidal cross-section flow channels, respectively. This showed that although the divergent flow channel structure reduces the fluid velocity in the flow process, it weakens the convective heat transfer performance in the flow channel. However, this gradually decreasing cross-sectional area improves the downstream heat transfer area and reduces the pressure drop in the flow process, thus promoting the overall heat transfer performance. With the increase in the circular radius (R), both the j and f factors increase, and the highest overall heat transfer performance is obtained at R = 300 mm. The convective heat transfer coefficient increases with the decrease in the inlet height.

Effect of Waveform Channel on the Cooling Performance of Hybrid Microchannel

To improve comprehensive hydrothermal performance of microfluidic cooling, a new type of hybrid microchannel is proposed. In this paper, turbulent flow and heat transfer characteristics of rectangular cross section straight hybrid microchannel, trapezoidal cross section straight hybrid microchannel, and trapezoidal cross section waveform hybrid microchannel (TWHM) are compared numerically by a realizable turbulence model under different pump power and heat flux. The results show that TWHM has a greater pressure drop at the same Reynolds number but has the best heat dissipation performance at the same pump power, in which temperature difference can be reduced up to 55.01%. The effect of arc height and chord length on the cooling performance of TWHM is also studied. As increases or decreases under the same pump power, the friction factor increases, while the total thermal resistance and bottom surface temperature difference decrease gradually. The cooling performance of channels becomes closer as the pump power increases. In addition, with the same cross-sectional area, the cooling performance of the waveform hybrid microchannel can be further improved by optimizing cross-sectional shape . The best cooling performance can be obtained at .

Numerical and Experimental Study of Cross-Sectional Effects on the Mixing Performance of the Spiral Microfluidics.

Mixing at the microscale is of great importance for various applications ranging from biological and chemical synthesis to drug delivery. Among the numerous types of micromixers that have been developed, planar passive spiral micromixers have gained considerable interest due to their ease of fabrication and integration into complex miniaturized systems. However, less attention has been paid to non-planar spiral micromixers with various cross-sections and the effects of these cross-sections on the total performance of the micromixer. Here, mixing performance in a spiral micromixer with different channel cross-sections is evaluated experimentally and numerically in the Re range of 0.001 to 50. The accuracy of the 3D-finite element model was first verified at different flow rates by tracking the mixing index across the loops, which were directly proportional to the spiral radius and were hence also proportional to the Dean flow. It is shown that higher flow rates induce stronger vortices compared to lower flow rates; thus, fewer loops are required for efficient mixing. The numerical study revealed that a large-angle outward trapezoidal cross-section provides the highest mixing performance, reaching efficiencies of up to 95%. Moreover, the velocity/vorticity along the channel length was analyzed and discussed to evaluate channel mixing performance. A relatively low pressure drop (<130 kPa) makes these passive spiral micromixers ideal candidates for various lab-on-chip applications.

Effect of Pitch Angle on the Winding Capacity of Nb3Sn Rutherford Cable

Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn Rutherford cable can be used in the next generation of superconducting magnets above 10 T which cannot be reached with NbTi strands. Rutherford cable is a multi-strand twisted cable with a two-layer structure and rectangle or trapezoidal cross section. Strands are fully transposed with respect to magnetic field. The pitch angle is important for Rutherford cable, which affects the AC loss and bending ability of the cable. Usually different magnets adopt different pitch angles according to the requirement. The winding capacity of the cable is one of a key point. To evaluate the influence of the pitch angle on the cable winding capacity and establish a reference for a new cable design, finite element method based on ABAQUS has been conducted to simulate the cable winding process.

Sagging damage characteristics of hull girder with trapezoidal cross-section subjected to near-field underwater explosion

To investigate the overall damage characteristics and failure modes of a warship subjected to an underwater non-contact near-field explosion, a hull girder with a trapezoidal cross-section was designed, manufactured, and tested. The design criteria and parameters were determined according to the similarity criterion. Dynamic responses of the girder freely floating on water were obtained under varying conditions, including stand-off distance, charge mass, and position of attack. Damage morphologies of the girder model were obtained. Based on our analysis, basic conditions for sagging damage of the hull girder are proposed. The aim of this study was to determine an efficient method of attack resulting in the most severe damage to the ship hull. The experimental results show that the girder mainly exhibits a first-order response when the first wet frequency of the girder is close to the frequency of the explosion bubble pulsation. The largest deformation was observed when the underwater explosion occurred directly below the midspan of the girder compared to other explosions of the same intensity at different attack positions. When the ratio of stand-off to maximum bubble radius (λ) satisfies 0.7 ≤ λ＜2, the bubble mainly causes sagging damage instead of hogging. As λ decreases (1≤ λ＜2), the sagging damage increases under the same charge mass. However, as λ decreases further (0.7≤ λ＜1), the sagging deformation decreases. This is likely due to the impact of the liquid jet formed by the collapsing bubble, which causes the girder deformation to shift from sagging back to hogging deformation. The initial shock wave excites the high-frequency response of the girder structure but contributes very little to the overall velocity and displacement. However, bubble pulsation typically causes a low-frequency response, which will affect the velocity and displacement of the girder. The low-pressure region of the flow field formed by bubble pulsation and resonant coupling between the girder and the bubble are the predominant causes of damage to the overall girder structure.

Evaluation of thermo photovoltaic performance through aluminum-fueled combustor with partially porous medium and different geometric cross-sections

Thermo photovoltaic (TPV) power generation systems have attracted a great deal of attention in the field of portable electronic devices. The high and uniform temperature of TPV combustor plays a decisive role in the improvement of system efficiency. In this study, aluminum is utilized as energy source of TVP. To model the premixed combustion of aluminum-air, an asymptotic model of flame structure including four zones of solid, liquid, and gaseous aluminum and post-flame and three asymptotic fronts of melting, evaporation, and flame is proposed. Then, the conservation equations and boundary conditions are derived and the combustion characteristics of aluminum are obtained. Combustion is evaluated for simple and porous media with trapezoidal, rectangular, triangular, and circular cross-sections. Finally, the influence of parameters on the TVP performance is assessed. The results indicated that in the medium with a porosity factor of 0.8, the total efficiency is higher than the simple medium for all cross-sections. In the medium with a porosity factor of 0.6, however, the triangular and circular cross-sections exhibit lower efficiency compared to the simple medium. In the case with a porosity factor of 0.4, only the efficiency of the channel with a trapezoidal cross-section is higher than the simple medium.

Midchannel islands in lowland river corridors and their impacts on flow structure and morphology:A numerical based conceptual analysis

Midchannel islands (MCIs) are influential geomorphic units in regulating morphological and ecological dynamics in sand-dominated rivers. The primary objectives of the study were to understand a) the relationship between morphometric characteristics of the basin and the occurrence location of the MCIs, b) the role of MCIs on the hydraulic gradient and the other hydraulic variables along the reach, and c) the influence of island growth process on hydrodynamics in the wake and contraction regions. Spatial distributions of MCIs depending on the morphometric features of the three characteristic basins were considered. While the basin-scale analysis was conducted using GIS-based data, the reach and individual scale analyses were performed based on a Reynolds-averaged Navier–Stokes (RANS) model. Uniform circular cylinder and island geometries were exposed to identical flow conditions. The expansion of these island geometries was mimicked both in rectangular and trapezoidal cross-sections. The variation of water surface slope and bottom shear stress variables, which greatly trigger the intensive bilateral interaction between hydrological-morphological-ecological elements in river corridors, depending on the growth of the island, was determined. The role of imposed island geometry on the secondary flow structure within the downstream cross-section of the island and streamwise velocity fluctuations in contraction regions were analyzed. The basin-scale analysis showed that with decreasing basin slopes, the family of islands emerged at a longer distance to the basin outlet. It was also seen that MCIs location is closer to the basin outlet forbasins with a lower aspect ratio. Besides, asymmetrical large-scale counter-rotating streamwise vortices were detected behind the MCIs based on numerical simulations. GIS-based data showed that this coherent flow structure brought about channel adjustments in downstream of the island. In addition to morphological consequences, it was hypothesized that this alteration in the flow structure due to MCI has potential impacts on riverine ecology. These impacts are increase in groundwater recharge, vertical exchange of surface–subsurface water, local heterogeneity in sediment characteristics (i.e., convenient fish spawning areas), and enlargement in the hyporheic zone.

ОПРЕДЕЛЕНИЕ ТРЕЩИНОСТОЙКОСТИ ПРЕДВАРИТЕЛЬНО НАПРЯЖЕННЫХ ЖЕЛЕЗОБЕТОННЫХ БАЛОК ТРАПЕЦИЕВИДНОГО ПОПЕРЕЧНОГО СЕЧЕНИЯ

Beams of a trapezoidal cross-section with a wide upper edge with prestressed reinforcement combine positive qualities in terms of strength, crack resistance, deformability and resource saving, which allows them to cover significant spans of multi-storey buildings. &#x0D; To develop a method for calculating the moment of cracking in these structures, a nonlinear deformation model was adopted, which includes equilibrium equations, conditions for the linear distribution of relative deformations along the height of the element section, and refined deformation diagrams of concrete and reinforcement. Concrete state diagrams are assumed to be nonlinear without a falling branch. To describe the deformation diagrams of high-strength and conventional reinforcement, a universal dependence is adopted, consisting of one linear and two nonlinear equations, in which the calculation of individual parameters is performed using different formulas. For the initial stage of the crack formation process, a design scheme is presented, in accordance with which the necessary equations and ratios are drawn up in relation to the considered prestressed reinforced concrete beam of a trapezoidal cross-section. &#x0D; The purpose of the study, in addition to developing a calculation methodology, was also the development of an algorithm and a computer calculation program. To obtain and analyze the results, a numerical experiment was carried out, the results of which are presented in tabular form. Due to the fact that the calculation method was built without involving empirical dependencies, the possibility of its application to determine the crack resistance of prestressed reinforced concrete beams of trapezoidal cross-section for any class of concrete and reinforcement was confirmed.

Application of mechanistic force models to features of arbitrary geometry at low material removal rate

This paper presents a workpiece discretization method to apply existing cutting force models to predict the forces generated during low material removal rate robotic machining operations of features with arbitrary geometry. Two machining operations along a straight edge which are modelled using this feature discretization method are shown, a chamfer pass on a sharp corner and the removal of a trapezoidal cross section. The workpiece features are measured using a high-resolution laser profile scanner to obtain the volume of the features to be removed. The identified features are discretized into rectangular sections such that the cutting force models can be applied to predict the cutting forces. A linear and an exponential mechanistic model which relate tool immersion and feed rate to the cutting force are applied to the scanned workpiece features. The linear and nonlinear models show good agreement with the measured data, with the exception that the linear model occasionally over predicts the forces depending on the radial depth of cut.

Optimization of the cross section of a novel rail running conveyor system

The throughput of a belt conveyor system is the primary design parameter when considering a new installation, determined by the cross-section of the material on the belt, coupled with the belt speed. Optimizing this area not only improves efficiency, but also minimizes capital costs through the optimal selection of equipment. Whilst speed-related optimization has seen considerable attention, the cross-sectional area has largely been neglected due to existing design constraints of the system. Conventional belt conveyors typically utilize a 3-idler troughing configuration, which forms a trapezoidal cross-section with a parabolic surcharge. The rigidity of this support directly limits the geometry of the cross-section that may be considered. A new conveyor system developed at the University of Newcastle supports the conveyor belt by a rail-based carriage, with no relative movement between the belt and carriage. This configuration allows the cross-section of the belt to be freely optimized in order to maximize the material throughput for a given belt width, or alternatively to minimize the belt width for a given throughput. This article utilizes the calculus of variations to optimize the form of this cross section, and demonstrates that an increase in throughput of up to 30% is possible, compared to troughed installations.

Comparative Study on Thermos-Hydraulic Performance of Different Cross Section Shapes of Microchannels with Supercritical CO2 Fluid

The influence of the cross section shape of microchannels on the thermos-hydraulic performance of the supercritical CO2 fluid is an important issue in the design of industrial compact heat exchangers, but few studies have been conducted about this issue. In this paper, comparative studies of the flow and heat transfer performance of SCO2 fluid in horizontal microchannels with circular, semicircular, rectangle, and trapezoidal cross sections were conducted numerically. The comparison is based on the same hydraulic diameter and length for all channel types and is carried out under the same mass flux, outlet pressure, and wall heat flux. The fluid bulk temperature in this analysis ranges from 285 K to 375 K, which covers the pseudocritical point of SCO2. The results show that the circular channel has the highest average heat convection coefficient, while the trapezoidal channel has the worst convective heat transfer performance under the same hydraulic diameter and boundary conditions. The results also indicate that the effect of cross section shape on the heat convection coefficient is significantly greater than that on the channel pressure drop, and the existence of the corner region in the cross section, especially the acute angle, will weaken the heat transfer performance.

Accurate Open Channel Flowrate Estimation Using 2D RANS Modelization and ADCP Measurements

Boat-mounted Acoustic Doppler Current Profilers (ADCP) are commonly used to measure the streamwise velocity distribution and discharge in rivers and open channels. Generally, the method used to integrate the measurements is the velocity-area method, which consists of a discrete integration of flow velocity over the whole cross-section. The discrete integration is accomplished independently in the vertical and transversal direction without assessing the hydraulic coherence between both dimensions. To address these limitations, a new alternative method for estimating the discharge and its associated uncertainty is here proposed. The new approach uses a validated 2D RANS hydraulic model to numerically compute the streamwise velocity distribution. The hydraulic model is fitted using state estimation (SE) techniques to accurately reproduce the measurement field and hydraulic behaviour of the free-surface stream. The performance of the hydraulic model has been validated with measurements on two different trapezoidal cross-sections in a real channel, even with asymmetric velocity distribution. The proposed method allows extrapolation of measurement information to other points where there are no measurements with a solid and consistent hydraulic basis. The 2D-hydraulic velocity model (2D-HVM) approach discharge values have been proven more accurate than the ones obtained using velocity-area method, thank to the enhanced use of the measurements in addition to the hydraulic behaviour represented by the 2D RANS model.

Determination of an allowable value of internal uniform pressure on the underground horisontal working contour with a trapezoidal form of its cross-section

The paper presents the study results of the stress state at the contour points of an underground horizontal working carried out by the methods of the complex variable theory. This study is the basis for solving the problem of determining an allowable value of the uniform pressure transmitted to the contour of the working, with predetermined values of the depth of its laying. The condition proposed by the authors of the paper is used as a criterion of strength (stability), according to which the working’s contour strength is ensured if at any point the amount of the tangential normal stress does not exceed the tensile and compressive strength of the host soil (rock), i.e. σt ≤ σe ≤ σc . As a result of the solution, an assessment of the stress distribution on the contour of an underground horizontal working has been made. The working has a cross-section in the form of a curved trapezoid, which is under the action of uniform all-round stretching of a given intensity with a varying depth and various values of the host mass lateral expansion coefficient. The allowable values of the tensile internal pressure on the contour of an underground horizontal working of a trapezoidal cross-section have been determined at the given values of its depth and a constant coefficient value of the lateral expansion of the host mass μ = 0.25. The materials presented in the paper can be used when choosing the maximum or minimum allowable depth of the working used as a storage facility for liquid or gaseous hydrocarbons.

Geometry and shape optimization of piezoelectric cantilever energy harvester using COMSOL multiphysics software

AbstractIn embedded systems that necessarily require a steady source of power and (or) attaches to a sensor(s), there are opportunities to mix small batteries to supply such power. The aim of this research is to optimize the geometry and shape of piezoelectric cantilevers to harvest more power. Several piezoelectric cantilever geometries with various shapes (rectangular, triangular, circular, and trapezoidal cross section) are tested in COMSOL multiphysics simulator to find the best geometry that provides the highest accomplishable power. The most efficient geometry was found to be conferred by the trapezoidal, cross section cantilever. Next, another improvement method was applied to maximize the harvested power of the cantilever by modifying the shape of the trapezoidal cantilever structure through increasing the number of its faces. The results demonstrated that the highest output power (36 mW) was produced by the four faces, trapezoidal cross section design of cantilever.

Design and Comparative Cost Analysis of Alternative Prefabricated Beef Cattle Barns with Conventional Barn Types

In this study, planning, design and cost analysis of prefabricated beef cattle barns carried out. Steel mesh was used to strengthen the foundation of the structure. Galvanized-sheet material was used as the carrier and cover material, and shaped like a trapezoid cross-section. The barns, which are planned in the form of tunnel cross-section and tie-stalls type, are designed for 10, 20 and 30-cattle to be particularly suitable for family enterprises. Polyurethane (PU) foam and extruded polystyrene sandwich panel (XSP) were used to provide heat and sound insulation. Cost analysis of the galvanized-sheet barns was compared with the barns constructed by the traditional production method. After analyses, we found that as the number of animals increased, barn cost per animal decreased. The cost reduction rates in the PU foam insulated galvanized-sheet barn were 30.1%, 32.7% and 30.6% for the 10, 20 and 30-cattle respectively. These values were 24.9%, 27.8% and 25.5% for the sandwich panel insulated galvanized-sheet barn. The most economical combination was the polyurethane foam insulation of galvanized sheets. Galvanized-sheet barns are technically sufficient, and economically advantageous than the conventional ones, so it can be recommended to both newly established enterprises and enterprises that want to improve their old barns.