Trapezoidal Cross-section Research Articles

Rapid Tooling for Microinjection Moulding of Proof-of-Concept Microfluidic Device: Resin Insert Capability and Preliminary Validation

Producing sustainable microfluidic devices on a large scale has become a trend in the biomedical field. However, the transition from laboratory prototyping to large-scale industrial production poses several challenges due to the gap between academia and industry. In this context, prototyping with a mass production approach could be the novel strategy necessary to bridge academic research to the market. Here, the performance of polymer inserts to produce PMMA microfluidic devices using the microinjection moulding process is presented. Inserts were fabricated with an additive manufacturing process: material jetting technology. The importance of the inserts’ orientation on the printing plate in order to produce samples with more uniform thickness and lower roughness has been demonstrated using a flat cavity insert. In addition, preliminary tests were carried out on microstructured inserts with inverted channels of various cross-section shapes (semi-circular or trapezoidal) and widths (200 or 300 µm) in order to investigate the microstructures’ resistance during the moulding cycles. The best geometry was found in the channel with the trapezoidal cross-section with a width equal to 300 µm. Finally, a preliminary microfluidic test was performed to demonstrate the devices’ workability.

Composite Delta Beam for Slim Floor Construction

Abstract: The structural behaviour of the composite Flush Beam for slim floor as a whole has been investigated. The deformation behaviour of the structural members Steel beams with trapezoidal cross-sections and specially punched webs were developed as composite beams in slim floors. The estimation of the flexural stiffness and bending capacity of composite slim beams is rather complicated, because the influence of many factors should be taken into account. These factors include variable section dimensions, Profile of the beam, stiffness of the beam and interaction between steel and concrete. In this paper, analytical investigations have been conducted to investigate the deflection behaviour of Flush beam specimens under monotonic loading. A design procedure is developed for composite slim floor Flush beams based on cross-sectional analysis and the flexural properties of the slim floor beams are evaluated. From the analytical investigation it was found that the deflection of delta beam is 48% less than the conventional I-beam More over the stiffness of the Delta beam is 49.8% higher than the I-beam

Pure Effect of Temperature on Rectangular and Trapezoidal Box-Girder Bridges – A Finite Element Investigation

Since the temperature distributions on concrete bridges are nonlinear, they lead to the self-equilibration of the stress distributions. To have a discussion about strains, deflection, and moment brought on by temperature changes. Three-dimensional finite element, Computers and Structures, Inc (CSI) Bridge finite element software is used to analyze 2 box girder bridge specimens; rectangle and trapezoidal cross section. The box girders were same in depth, span length, cross section details and material properties. These specimens were subjected to different temperatures values. They were tested under AASHTO thermal loading and temperature gradient specification. The finding showed that changing the temperatures at a constant rate during the days of the year, by increasing and decreasing, affects by a fixed amount all of the values of deflection, stresses, and moments, for each of the rectangular and trapezoidal sections by the same amount. Through the values of deflection, stresses and moments for both the trapezoidal section and the rectangular section, it can be seen that the trapezoidal section is affected by the temperature change in a lesser way than the rectangular section. That happened because the rectangular section is affected by the temperature gradient along the section in a greater proportion than the trapezoidal section by 16% in stresses and 56% in terms of deflection.

Properties of hybrid glued-laminated timber manufactured from peeler cores

ABSTRACT The aim of the present study was to determine some basic physical and mechanical properties of a hybrid glued-laminated timber manufactured from peeler cores (GLPC) as by-products of plywood manufacturing, ensuring more complete and efficient utilisation of wood raw materials in high value-added applications. The GLPCs were manufactured from beech and poplar wood at different ratios by using several combinations of lamellae with trapezoidal cross-sections. The highest density ρmax of 572 kg.m−3 (ρmean = 544 ± 12.9 kg.m−3) was determined for the beams manufactured at beech:poplar ratio of 1:1. The modulus of rupture (MOR) and modulus of elasticity (MOE) were 71 ± 9.4 N.mm−2 and 12,809 ± 1211.7 N.mm−2, respectively. The highest shear strength were obtained for the beams manufactured by gluing beech to beech: f v , g , k ( 60 ) = 17 ± 3.8 N.mm−2. The greatest values when testing the compressive strength and tensile strength of the GLPC were found for combination beech 50%/ poplar 50%: f c , g , k ( 90 ) = 60 ± 8.6 N.mm−2 and f t ( 0 ) , g , k = 42 ± 8.0 N.mm−2. All types of beams produced in laboratory conditions met the minimum requirements of the GL 32c and GL 32 h classes.

Two-phase flow dynamics study in the trapezoidal gas channel of PEM fuel cell based on lattice Boltzmann model

ABSTRACT Water management is a critical challenge in ensuring the performance and durability of low-temperature proton exchange membrane fuel cells (PEMFCs). This study utilizes the phase-field lattice Boltzmann method to conduct three-dimensional numerical simulations, investigating the dynamics of two-phase flow in the cathode gas channel (GC) of PEMFC with a trapezoidal cross-section. The effects of the water inlet location, the surface wettability of GC, the open angle of GC, and the air velocity on liquid water distribution and discharge are analyzed. The results indicate that positioning the water inlet in the middle of the GC significantly enhances PEMFC performance while having minimal impact on average pressure drop. A wall contact angle of 70° or 110°Can optimize fuel cell performance from different directions. Setting a wall contact angle at 70° optimizes gas flow stability and maintains a low-pressure drop value for the GC. A wall contact angle of 110° focuses on optimizing gas reactant diffusion ability into porous electrodes and GC drainage rate. An opening angle of 55° for the trapezoidal gas channel improves overall fuel cell performance. Increasing air velocity facilitates the film flow formation of liquid water on top wall surfaces within the GC.

Automated Generation of Hydraulic Models and its use for Sensitivity Analysis: Response Time Variation with Channel Parameters

A first prototype of a Python package that can generate input for, perform runs of, and the analyse output of the Delft3D FM 1D2D simulation software corresponding to both simple and complex canal networks is demonstrated. The package can, for instance, generate input files for a canal system with a wide range of friction values and a range of variations on the design cross sections and structures used. It can then start parallel Delft3D runs for these input files. Finally, results can be analysed from Python. Results are presented for the rise time associated with a step change in the discharge for a prismatic canal with a trapezoidal cross section and either a weir or a gate at the downstream end. The size of the step change, the parameters of the cross section, the friction, and the canal slope are varied.

Development of a Microfluidic Device for Blood Cells Extraction in Liquid Biopsy

This project aims to produce a microfluidic device capable of separating 6 μm and 20 μm diameters particles by inertial sorting. This Lab-on-Chip (LoC) was designed with a trapezoidal cross-section for better fluid control and effective particle manipulation at the microscopic level, as demonstrated by COMSOL simulations. The device was manufactured on a substrate of Polymethyl Methacrylate (PMMA) by femtosecond laser technology and then assembled using an innovative geometry-preserving Isopropyl alcohol-based procedure. The LoC was test with spherical plastic microparticles of two diameters (6 μm and 20 μm) suspended in distilled water. The separation efficiencies were (98.2 ± 1.6) % for 20 μm diameter particles and (70.0 ± 1.8) % for 6 μm diameter particles in good agreement with the simulation results. Finally, after a microfluidic channels’ acetone vapors treatment, the device demonstrated a good ability to separate biological particles (Red Blood Cells) at different concentrations (20%, 30%, 40%, 50%) in a PBS buffer.

Mechanical analysis of radial performance in biodegradable polymeric vascular stents manufactured using micro-injection molding

Micro-injection molding (MiM) is a promising technique for manufacturing biodegradable polymeric vascular stents (BPVSs) at scale, in which a trapezoidal strut cross section is needed to ensure high-quality de-molding. However, there is a lack of research on the influence of the strut cross-sectional shape on its mechanical properties, posing a challenge in determining the key geometries of the strut when using MiM to produce BPVSs. Hence, this work has investigated the relationships between the geometry parameters, including the de-molding angle, and the radial support property of BPVSs using the finite element method. The results reveal that the radial stiffness of BPVSs is significantly affected by the de-molding angle, which can be counteracted by adjusting strut height, bending radius, and strut thickness. Stress distribution analysis underscores the crucial role of the curved portion of the support ring during compression, with the inner side of the curved region experiencing stress concentration. A mathematical model has been established to describe the relationships between the geometry parameters and the radial support property of the BPVSs. Notably, the radius of the neutral layer emerges as a key determinant of radial stiffness. This study is expected to serve as a guideline for the development of BPVSs that can be manufactured using MiM.

Effects of Different Channel Geometries of Metallic Bipolar Plates on Proton Exchange Membrane Fuel Cell Performance

This paper investigates the effects of different channel geometries on the performance of Proton Exchange Membrane Fuel Cells (PEMFCs). The study employs computational fluid dynamics (CFD) coupled with thermal and electrochemical simulations to analyze five channel geometries (cases A to E) of bipolar plates. A thorough study on this topic is not found in the literature and aims to identify designs that optimize performance and align with cost-effective production methods. Among the various studied geometries, case D, featuring a trapezoidal cross-section, exhibited the most favorable performance compared to the others, with a current density value of 2.01 A/cm2 and a maximum temperature of 74.89 °C at 0.3 V, leading to an increase in generated power of 4.46%, compared to base case A. The trapezoidal shape enhanced the contact area with the reacting region, resulting in higher reaction rates and an improved overall performance. However, the study also highlights the relevance of velocity and turbulence, with case B demonstrating an enhanced performance due to its higher velocity, and case E benefiting from localized higher velocity regions and turbulence created by baffles. Case B can increase generated power at its peak by around 3.21%, and case E can improve it by 1.29%, with respect to case A. These findings underscore that contact area has a major impact on the PEMFC performance, but velocity and turbulence also play relevant roles. Additionally, trapezoidal channels can be easily manufactured through sheet metal-forming techniques, aligning well with new market trends of weight and cost reduction on bipolar plates. Fuel and oxygen utilization percentages, 38.14% and 62.96% at 0.3 V, respectively, further confirm the superiority of trapezoidal channels, providing insights into optimizing the PEMFC performance. This exhaustive study contributes valuable information for designing efficient metallic bipolar plates and advancing the development of practical fuel cell technologies.

Experimental Study on Vertical Bearing and Deformation Characteristics of Qiantang River Ancient Seawall

Situated on the northern bank of the Qiantang River estuary, the ancient seawall serves not only as a national cultural relic but also as an active agent in flood and tide prevention. This seawall features a trapezoidal cross-section and is constructed with layered stone blocks and a sticky rice mortar. To investigate the load-bearing and deformation attributes of this ancient structure, a scaled-down specimen with a ratio of 1:4 was created. Monotonic and cyclic vertical loadings were then applied to the wall’s top surface. During these loading procedures, measurements of the loading force, seawall displacement, and front and side deformation fields were taken. Experimental findings reveal that the seawall tends to lean towards the soil-retaining side under vertical loading. After ten loading cycles, the vertical rigidity of the wall was reduced by 10%. Upon application of a uniformly distributed vertical load of 1.6 MPa at the top of the wall, significant cracks began to materialize in the blocks at the base of the seawall. When the loading at the top increased to 2 MPa, a vertical crack that cut through the mortar layer at the wall’s center was observed. By comparing it to a three-dimensional finite element model, the load-bearing and deformation characteristics of the ancient seawall observed in the experiments were confirmed, which could contribute to the scientifically informed conservation and protection of the seawall.

Toroidal Nanocrystalline Powder Core With Trapezoidal Cross Section

This paper introduces a toroidal nanocrystalline powder core with a trapezoidal cross section. The non-uniform magnetic flux distribution of toroidal cores with different cross sectional geometries is discussed, the inductance equations are derived, and the geometrical optimisation factor is given in order to retain the highest possible inductance value whilst minimising material usage. A 10-turn coil is wound on the core, with the measured inductance values showing a good match with both FEM and mathematical calculation. The near-field electromagnetic interference (EMI) radiation in close proximity to the inductor is investigated by both FEM and experimental validation, and the toroidal core with a trapezoidal cross section has shown reduced EMI. By adopting a trapezoidal cross section for the toroidal core, a 30 % reduction in material usage and lower EMI are achieved, albeit with a compromise of 14% in inductance.

Misfit stress and energy in composite nanowire with polygonal core

In this article we present for the first time an analytical solution to the boundary-value problem in the classical theory of elasticity for a core-shell cylinder with an eccentric prismatic core having a trapezoidal cross section and subjected to uniform dilatation eigenstrain. In doing so, we represent the trapezoidal prism as a superposition of long straight dilatational lines located along the cylinder axis. The complex potential approach has been employed to satisfy the boundary conditions on the cylinder free surface. Found in a concise and transparent closed form, the elastic stresses exerted by the dilatational line and dilatational prismatic inclusion (of trapezoidal cross section) in cylindrical body are demonstrated with maps. The mean stress is employed to obtain the analytical expression of strain energy stored by the dilatational inclusion in form of regular prism symmetrically placed in cylindrical body. It is proved that the strain energy is identical to the one of cylindrical inclusion with the same cross section area.

Enhancing PEMFC performance through orifice-shaped cathode flow field designs: A multiscale, multiphase simulation study on oxygen supply and water removal

In this study, a multiscale, multiphase polymer electrolyte membrane fuel cell (PEMFC) model was applied to simulate the cell performance of six cathode flow field designs. These designs included conventional flow field layouts (with trapezoidal and rectangular cross-sections) as well as orifice-shaped flow field designs featuring various narrowing section arrangements. The simulation results indicated that, in general, the orifice-shaped flow field designs yielded higher oxygen concentrations within the cathode side and exhibited superior water removal capabilities compared to conventional flow field designs. This study further revealed that the positioning of the narrowing section significantly influences cell performance, with enhanced performance noted in the orifice-shaped design that incorporated a zigzag pattern between adjacent channels. This pattern outperformed the side-by-side arrangement, implying that the zigzag configuration offers a superior advantage in optimizing oxygen supply and water removal.

Simplified heat-transfer calculation for the trapezoidal cross-section wall in Gobi solar greenhouses and greenhouse thermal-load prediction

Simplified heat-transfer calculation for the trapezoidal cross-section wall in Gobi solar greenhouses and greenhouse thermal-load prediction

Experiment study on heat transfer enhancement of micro heat pipe PV/T by Reynolds number improvement

The rapid performance improvement of photovoltaic/thermal (PV/T) implies great potential application to various aspects of society. The previously developed micro heat pipe PV/T by our team has shown favorable cogeneration of electricity and heat in cold regions, while it is badly needed to improve its comprehensive performance by enhancement of heat transfer. For same working fluid as HCFC141b in micro heat pipe, higher Reynolds Number (Re) theoretically means better heat transfer. Therefore, two available micro heat pipes were developed with trapezoidal cross section and rectangular cross section respectively while with same cross section area and applied in two micro heat pipe PV/T systems. Subsequent experiment study testifies that the rectangular micro heat pipe PV/T of higher theoretical Re verily shows more favorable performance than the trapezoidal micro heat pipe PV/T when they are at 45° inclination angle. Deducting power consumption of circulating pump, the average electrical efficiency of rectangular micro heat pipe PV/T system is 12.4%, while that of trapezoidal micro heat pipe PV/T system is 11.9%. Moreover, the thermal efficiency, total energy power, and total energy efficiency of rectangular micro heat pipe PV/T system are respectively 28.1%, 472.3 W, and 40.5%, which are 10.1%, 119.8 W, and 10.8% higher than those of trapezoidal micro heat pipe PV/T system. The results are significant and valuable for the application of micro heat pipe PV/T in cold regions.

Novel three-dimensional 90° bend waveguides with high optical transmission efficiency based on silicon-on-insulator

Bend waveguide is an indispensable device in photonics integrated circuits (PICs). In this work, we propose and design two novel 3D 90° bend waveguides based on the silicon platform with asymmetrically semicircular and trapezoidal cross-sections. Strip bend waveguides with bending radii of 10/20 µm and cross-sectional size of 4 × 3.5/5 × 3.5 µm2 are used for comparison. The high optical transmission efficiency of the two novel 3D bend waveguides is validated by simulated data. The bent structures are manufactured on the device layer of silicon-on-insulator (SOI) using 3D grayscale lithography. The fiber-to-chip measured results indicate that at 1550 nm and TE/TM mode, the transmission efficiencies of the asymmetrically semicircular and trapezoidal bend waveguides with bending radii of 20 µm and cross-sectional widths of 4 µm are 1.91/1.66 dB and 1.36/1.15 dB higher than those of the strip bend waveguides. When the cross-sectional width is 5 µm, the two novel 3D bend waveguides are 1.99/1.72 dB and 1.46/0.98 dB higher than those of the strip bend waveguides. The 3D bend waveguides can effectively reduce the insertion loss. This research suits for the realization of highly integrated photonics computing chips.

3D trapezoidal edge coupler with high efficiency and tolerance based on Silicon-on-Insulator

Edge couplers connecting the optical fiber and the on-chip waveguide are indispensable devices in integrated photonics. In this study, a 3D edge coupler with trapezoidal cross-section is proposed and designed. High coupling efficiencies of the edge couplers are verified by theoretical calculations. The 3D trapezoidal edge couplers are fabricated on the thick-silicon layer of a Silicon-on-Insulator (SOI) substrate by using 3D grayscale lithography. Over the communication band (C-band), the fiber-to-chip measured results indicate that the maximum coupling efficiency of the 3D edge coupler is 0.68/0.99 dB for the TE/TM mode. The misalignment tolerances are less than 0.65 dB and 0.90 dB for the TE and TM modes within ±5 μm in the horizontal direction. The same measured values are less than 0.60 dB for both the TE and TM modes within 4 μm in the vertical direction. The excellent coupling characteristics of the 3D edge coupler are attractive for the large-scale photonic integration.

Nonlinear regimes of inertial wave attractors generated by a precessing lid: Zonal flows and Rossby waves

Fluid flow excited by inertial waves in a rotating annulus with a trapezoidal cross section is experimentally investigated. The forcing is introduced by the precession of a flat annular lid bounding the cavity. Such a setup allows to investigate interactions between inertial waves and zonal flows in the presence of equivalent topographic beta-effect, and its dynamic behavior under weak and strong forcing is experimentally studied for the first time. Due to the specific dispersion relation of inertial waves, a cavity shape supports wave attractors that appear only for retrograde lid precession. At a relatively low wave intensity, a zonal flow is generated in the vicinity of a “virtual” axial cylinder, the radius of which coincides with the radius of the focusing reflection from the conical bottom. A succession of non-linear regimes is observed as forcing increases, starting with a clearly identifiable case of triadic resonance. Further, the frequency spectrum is progressively enriched by emergence of additional discrete components, gradually reaching the state of “overheated” wave turbulence with a significant continuous background of the frequency spectrum. Finally, a strong low-frequency component develops in the frequency spectrum, and the continuous background of the spectrum decreases dramatically. The low-frequency component corresponds to azimuthally periodic structures identified as Rossby waves. In the case of strong forcing, a long-term variability of zonal-flow velocity at the timescale of tens of forcing periods is observed, which is likely a consequence of the interaction of azimuthal structures corresponding to a rich wave number set.

Fabrication of Spiral Low-Cost Microchannel with Trapezoidal Cross Section for Cell Separation Using a Grayscale Approach.

Trapezoidal cross-sectional spiral microfluidic channels showed high resolution and throughput in cell separation in bio-applications. The main challenges are the complexity and high cost of the fabrication process of trapezoidal cross-sectional channels on the micro-scale. In this work, we present the application of grayscale in microfluidic channel design to overcome the complexity of the fabrication process. We also use direct engraving with a CO2 laser beam on polymethyl methacrylate (PMMA) material to drastically reduce the microfluidic chip's cost (to <30 cents) and fabrication time (to 20 min). The capability of the present fabrication methodology for cell sorting applications is demonstrated through experimental tests for the separation of white blood cells (WBCs) from whole blood at different dilution factors. The experimental results indicated that an 800 µL/min flow rate provided the optimal separation efficiency using the fabricated chip. A 90.14% separation efficiency at 1% hematocrit diluted blood sample was reported.

Simulation of Oil Spills in Inland Rivers

The shipping volume in inland waterways has been rapidly increasing in recent years. However, it is still challenging to trace oil spills caused by maritime accidents. In this study, the oil spill dispersion trajectory in inland rivers was obtained by simulating the trajectory of oil particles under different waterway conditions based on a simulated flow field. Firstly, the flow field was simulated using a volume of fluid (VOF) model and the solution of an open-channel equation. Then, an oil particle diffusion and drift model was established using Python to simulate the diffusion of the oil. Finally, eight oil spill simulation scenarios were conducted with different channel shapes and cross-sections. The results showed that oil spills spread more extensively in a curved channel with a trapezoidal cross-section compared to other channel shapes and cross-sections. The findings of this research could be used to guide inland river environmental protection and oil spill trajectory tracking.