Right-angle Bend Research Articles

Research on the Prediction of Material Removal and Over-grinding Optimization for Abrasive Flow Machining of 3D Printed Right-Angle Bends

Research on the Prediction of Material Removal and Over-grinding Optimization for Abrasive Flow Machining of 3D Printed Right-Angle Bends

Enhancement of the degradation capacity of IsPETase by acidic amino acids insertion and carbohydrate-binding module fusion.

The biocatalytic degradation of poly(ethylene terephthalate) (PET) through enzymatic methods has garnered considerable attention due to its environmentally friendly and non-polluting nature, as well as its high specificity. While previous efforts in enhancing IsPETase performance have focused on amino acid substitutions in protein engineering, we introduced an amino acid insertion strategy in this work. By inserting a negatively charged acidic amino acid, Glu, at the right-angle bend of IsPETase, the binding capability between the enzyme's active pocket and PET was improved. The resulted mutant IsPETase9394insE exhibited enhanced hydrolytic activity towards PET at various temperatures ranging from 30 to 45 ℃ compared with the wild-type IsPETase. Notably, a 10.04-fold increase was observed at 45 ℃. To further enhance PET hydrolysis, different carbohydrate-binding modules (CBMs) were incorporated at the C-terminus of IsPETase9394insE. Among these, the fusion of CBM from Verrucosispora sioxanthis exhibited the highest enhancement, resulting in a 1.82-fold increase in PET hydrolytic activity at 37 ℃ compared with the IsPETase9394insE. Finally, the engineered variant was successfully employed for the degradation of polyester filter cloth, demonstrating its promising hydrolytic capacity. In conclusion, this research presents an alternative enzyme engineering strategy for modifying PETases and enriches the pool of potential candidates for industrial PET degradation.

Investigation on the Flow and Heat Transfer Characteristics in a Multi-Pass Channel Using Magnetic Resonance Velocimetry and Transient Thermochromic Liquid Crystal

Abstract The three-dimensional flow field in multi-pass channels with and without ribs was measured by magnetic resonance velocimetry (MRV), while heat transfer performance on the endwall of channels in the same geometry was investigated using transient thermochromic liquid crystal (TLC) technique. The evolution of comprehensive three-dimensional flow field and their correlation with local heat transfer enhancement on end wall of multi-pass channels with and without ribs were revealed as a whole picture. Results show that the flow characteristics in the right-angle bend as well as the second pass are dramatically different for the smooth and ribbed channels, resulting in totally different features of heat transfer distribution on the end wall in those two channels. For the smooth channel, strong dean vortices form around the bend region near the outer wall where heat transfer is enhanced substantially. For the ribbed channel, no dean vortex but complex three-dimensional flow presents around bends. Heat transfer downstream of ribs close to the reattachment regions is strengthened noticeably. Comparison between velocity and heat transfer results suggest that one of the principle mechanisms driving heat transfer enhancement is both endwall directed velocity for smooth and ribbed channels, even though they are induced by different flow structures.

Entrenchment of the Yellow River since the late Miocene under changing tectonics and climate

The distinctive right-angled bend of the Yellow River around the Ordos Block, a large Permo-Mesozoic continental block in East Asia, has attracted much attention from geomorphologists and geologists concerning its formation and evolution for more than a century. The Jinshaan Gorge, an over 600 km long entrenched reach of the Yellow River, currently connecting the Hetao Graben to the north and the Weihe Graben to the south, is considered to have developed in very recent geological time. However, the timing and processes of drainage integration between the two grabens and formation of the Jinshaan Gorge as a deeply incised form are still under debate, owing to limited data and various interpretations of them. In order to better understand the geomorphological evolution of the Yellow River, we investigated the sedimentology, magnetostratigraphy, and detrital zircon U-Pb dating in the upper Neogene and Quaternary deposits along the Jinshaan Gorge. We further integrated the new data with the sedimentary record of the adjacent basins in the northeastern Tibetan Plateau (NTP) and the basins around the Ordos Block, as well as the incision history of the Yellow River inferred from its terrace sequence. We show that the upper Neogene alluvial sediments preserved in the broad Tangxian valley along the Jinshaan Gorge are a mixture of materials from the Lvliang Shan and the Ordos Block. Importantly, they share almost the same provenance and zircon age spectra with the Pleistocene and Holocene Yellow River deposits. The broad Tangxian valley commenced incision during the Late Pliocene, followed by the formation of two Early Pleistocene terraces dated to ~2.2 Ma and ~1.2 Ma. The incision of the Yellow River and the accumulation in the basins were characterized by steady and slow rates before the Late Pleistocene, but an acceleration thereafter.We propose a three-stage evolutionary model for the development of the Yellow River, controlled by changing tectonics and climate during the Neogene. Before the late Miocene, an endorheic river system was developing in the Longzhong Basin. From the late Miocene to Early Pliocene, the Yellow River developed the current drainage system from the Longzhong Basin to the lower reach, constrained by the topographic pattern of the Ordos Block and its periphery, in turn controlled by coeval tectonic movements. Since the Late Pliocene, the Yellow River has undergone rapid incision with integration of the upper reach in the NTP and entrenchment in the upper and middle reaches, which were controlled by the continuously rising NTP and a deteriorating climate. The Tangxian valley developed and was filled between the end of the Miocene and Pliocene, approximately 8 to 3 Ma, and it was abandoned in the Late Pliocene in response to important climatic variations. The next acceleration in both incision and subsidence around the Ordos Block in the Late Pleistocene was also coeval with strong climatic oscillations, suggesting a possible link between climate and tectonics in the Neogene entrenchment history of the Yellow River.

Length correction model considering a right-angle bend of Fabry–Pérot sound absorbers

Aiming at the problem that the peak frequency of Fabry–Pérot (F–P) resonance metamaterials is shifted to high frequency due to the right-angle bend, we start from the mechanism of the frequency shift caused by the bend and propose a length correction theoretical model. Using the idea of equivalence, the effect of a corner is the first equivalent to the effective density. Then, the change in effective density is equivalent to the effective length, and the theoretical derivation is completed. This model can guide the length design of the F–P tube. Moreover, it can be used to predict the peak frequency of the F–P tube with a right-angle bend if its geometric dimensions are known. Through the analysis from theory, simulation, and experiment of two samples, the accuracy of the length correction theoretical model is verified. Additionally, by the power dissipation density and the dissipated energies, it is determined that the fundamental reason for the frequency shift is that the right-angle bend changes the distribution of power dissipation density in the tube. The work in this paper is of guiding significance for the frequency prediction and length design of F–P tubes.

The influence of mean flow velocity and direction on the acoustic transmission behavior of right-angled duct bends

Many duct systems transporting air flow also transport unwanted noise. The geometrical parameters of duct bends can be tailored to reduce the noise emission by blocking sound transmission through ducts. However, the flow velocity has an influence on sound propagation. So far, it is not clear to what extent this limits the transmission loss of bends and their usage for noise reduction. In this work, the influence of flow on the transmission loss of duct bends is studied numerically on the basis of a right-angled sharp bend with rectangular cross-section. The numerical method consists of two steps: First, a CFD flow simulation is done. These results are used as an input for the subsequent finite element acoustic simulation where the Helmholtz equation is solved. Thereby, the usage of two different flow models allows differing influences purely related to the uniform movement of the fluid from those related to additional flow phenomena like the flow constriction zone downstream of the bend. It is revealed that the impact of mean flow velocities up to 40 m/s is mostly negligible. However, flow direction plays an important role when higher order modes propagate, leading to significant differences between upstream and downstream transmission loss. Inter-modal acoustic scattering as well as mode transformation in the flow constriction zone have been identified as the reasons for these differences. The numerical results are confirmed by measurements.

Guiding temperature waves with graded metamaterials

Temperature waves exist in many practical scenarios such as pulse heat sources and periodic temperature fluctuations, which have broad applications for thermal nondestructive detection. However, it is still challenging to guide temperature waves in irregularly shaped pipes because temperature waves might be strongly scattered. To solve the problem, we propose a scheme to guide temperature waves with graded metamaterials that have continuous parameter variations in space. Since graded metamaterials can ensure the same phases of thermal wavefronts despite different spatial distances, temperature waves can propagate in irregularly shaped pipes without scattering. We then demonstrate an elementary unit to realize the right-angle bending of temperature waves. Experimental suggestions are also provided to design the elementary unit with common materials and layered structures. We further combine the elementary units together to realize three practical functions including obstacle avoidance, thermal periscope, and reverse bending. These results have potential applications for thermal imaging and sensing in elbow pipes.

Reflectionless plasmonic right-angled waveguide bend and divider using graphene and transformation optics.

In this work, a plasmonic right-angled waveguide bend and divider are proposed. Using the Transformation Optics (TO) approach the transformation media of a bend and a T-shaped divider are obtained. Such media with continuous refractive index are realized with the help of graphene in the terahertz frequency range, key to effectively guiding the surface plasmon polariton (SPP) propagation on the 90 degree curves. Components with such capability are promising for THz device applications.

Crossing the calcium spur with “sliding over the balloon technique” in anomalous anterior origin of right coronary artery with two right-angle bends

We present a simple novel technique of crossing the calcium spur at right-angle bend in coronary artery by deploying a noninflated balloon over the calcium spur where the tip of the passing stent frequently hits and create difficulty in negotiation of the stent forward. When we deploy a balloon over the calcium spur, the tip of the stent does not hit the edge of the calcium spur and the stent gently slides over the hydrophilic slippery balloon forward with ease. We describe a rare case of intervention in anomalous anterior origin of right coronary artery where we were not able to pass the stent across two 90° bends which were harboring calcium spur. In spite of we adopted buddy wire and triple wire technique to make the bend straight, we were not able to move the stent forward, each time it was hitting at the edge of the calcium spur. We put a 2 mm × 10 mm noninflated semicompliant balloon each time while crossing the right-angle bend with calcium spur which covered the calcium spur and over the balloon we were easily able to slide the stent forward, deployed the stent across the lesion, and achieved distal TIMI III flow. We describe this simple novel technique of “sliding the stent over the balloon technique” to cross the calcium spur remaining at 90°-angle bend causing difficulty in forward negotiation of the stent.

Terahertz low-pass filter based on cascaded resonators formed by CPS bending on a thin membrane.

A membrane-based coplanar-stripline (CPS) transmission-line platform has recently enabled implementation of diverse THz system-on-chip (TSoC) components. In this paper, we demonstrate an elliptic-function THz low-pass filter (TLPF) using cascaded λ/4 resonators between the right-angle bending of a CPS transmission line defined on a 1 μm-thin membrane. We investigated the effect of bending the CPS transmission line with different angles that introduces a frequency response similar to a simple LC low-pass filter (LPF) and facilitates the design of a desired roll-off performance using traditional methods. ANSYS HFSS was used to provide a full-wave analysis and characterize the effective parameters of the TLPF with a designed cutoff-frequency around 0.6 THz. Using 7 sections of right-angle CPS bending with total length 1.4 mm, we demonstrate experimentally an elliptic-function TLPF characterized by a low-ripple at passband, a roll-off transition with zero transmission near the cutoff frequency and a wide stopband with -60 dB rejection.

Resistance characteristics analysis of droplet logic gate based on lattice Boltzmann method

In this paper, the geometric models of microfluidics NON-AND and AND-OR droplet logic gate devices are designed, and the operations of NON-AND and AND-OR logic are implemented in the designed models. Based on the color-gradient model (R-K model) of lattice Boltzmann method (LBM), the two-phase flow pattern in microchannel is simulated. Based on the “equivalent length method”, the Laplace resistance at the droplet phase interface and the local resistance at the right-angle bend are equivalent to the additional pipe length required for continuous phase flow in the channel to generate the same on-way resistance increment, and the resistance characteristics when slug flow droplets exist in the microchannel are quantitatively analyzed. The method is further applied to the analysis of the resistance characteristics of the droplet logic gate, and the quantitative explanation of the droplet path-choosing behavior is obtained. Compared with the “hydroelectricity analogism method”, the “equivalent length method” is more concise and easy to understand. The research results in this paper provide theoretical basis for the design of other forms of droplet logic gate devices.

Right-Angled Coplanar Waveguide Using Short-Circuited Slotline

In this article, a right-angled coplanar waveguide using the short-circuited slotline is proposed to eliminate the coplanar waveguide mode to coupled slotline mode conversion suffered by the conventional right-angled coplanar waveguide. As compared with the simulation and measurement results of the conventional right-angled coplanar waveguide, the reflection coefficient is greatly reduced from -2.44 to -9.52 dB, whereas the transmission coefficient is greatly increased from -16.07 to -4.49 dB. Besides, the peak-to-peak noise of the time-domain reflection is reduced from 0.033 to 0.027 V, whereas the peak-to-peak noise of the time-domain transmission is reduced from 0.040 to 0.029 V. Furthermore, the electric fields of the inner and outer slots of the coplanar waveguide are now made equal phase throughout the right-angled bend. As a result, the power loss is reduced from 60% to 55% and the signal integrity is improved.

Optimal Design and Experimental Investigation of a Compact Ka-Band Mode Converter System

A novel synthesis method is used to design the 32-GHz high-power microwave (HPM) mode converter system in this paper. The mode converter system includes a TE01 right-angle bend transition, a TE01 mode taper, and a TE01–TE11 mode converter. The new synthesis method provides more compact structure dimensions and higher mode conversion efficiency. The transmission efficiencies for three parts above are 99.21%, 99.87%, and 99%, respectively. Last, the mode converter system is fabricated, assembled, and tested on gyrotron experimental platform. The test results indicate the validity and the accuracy of the novel synthesis method.

Sound Radiation from Vehicles on the Right-Angle Bend of the Road

Sound radiation from vehicles traveling on a city road with a right-angle bend is studied. The effect of wind on the acoustic field is taken into account. First, a solution to the problem for two-point noise sources moving in opposite directions is found using the integral Fourier transforms over space variables and time. Inverse transforms are calculated approximately using the stationary phase method. A solution to the general problem is obtained as a superposition of many partial solutions. The numerical analysis of traffic noise characteristics is carried out for the case of a dual carriageway Textile Workers Avenue in the town of Łodź, Poland.

Planar, Multifunctional 3D Printed Antennas Using Liquid Metal Parasitics

This paper describes a liquid metal-based multifunctional antenna capable of wideband frequency tuning, dual band operation, and polarization reconfiguration. The radiating elements consist of parasitically-excited plugs of room-temperature liquid metal in 3D printed channels. Syringe pumps flow the gallium-alloy plugs in proximity to a capacitive feeding structure. This non-contact feeding scheme separates the metal flow path from the SMA connector and lends mechanical robustness at the feed while allowing impedance matching over a wide range of frequencies. Sliding the plug along a right-angle bend enables linear polarization reconfiguration, while simultaneously placing plugs in both orthogonal channels can generate circular or 45° linear polarization. Dual band operation is also supported by infusing plugs of two dissimilar lengths into the two channels. Simulation and measurement results demonstrate that this antenna can tune its impedance over a decade (10:1 frequency range) maintaining a 2:1 VSWR and achieve a polarization diversity >12 dB. The pumped plugs can circulate at a peak velocity of 50 mm/s, currently limited only by our pumping equipment. Repeatability analysis is also performed by cycling the plug actuation more than 1100 times. More complex designs can exploit this design concept to develop new types of highly versatile, multi-functional antennas.

AARF: Any-Angle Routing for Flow-Based Microfluidic Biochips

Flow-based microfluidic biochips are promising with significant applications for automating and miniaturizing laboratory procedures in biochemistry. Automated design methods for flow-based microfluidic biochips are becoming increasingly important due to the advancement in both integration scale and design complexity for complicated biochemical applications. Though the multilayer soft lithography fabrication provides flexibility to route both flow and control channels in any angle, existing routing algorithms still adopt Manhattan routing metrics, which design channel in either vertical or horizontal direction only. Moreover, based on the computational fluid dynamics analysis, rectilinear channels with 90° bends have the following issues: 1) reduced the fluidic flow rate, which degrades the performance of the biochip and may even result in the erroneous outcome of the whole procedure and 2) increased pressure at the right-angle bend, which negatively affects the reliability of the biochip. To fully utilize the routing flexibility, this paper proposes the first any-angle routing algorithm for flow-based microfluidic biochip, called AARF. Computational simulation results show that compared with traditional Manhattan routing method, the proposed AARF significantly improves the total wirelength and total effective wirelength (considering the turning angles) by 17.11% and 35.91%, respectively, which prove the effectiveness of the AARF routing flow.

Three-dimensional transformation optics for arbitrary coordinate systems: transforming conductive materials and boundaries.

A three-dimensional transformation optics method, leading to homogeneous materials, applicable to any non-Cartesian coordinate systems or waveguides/objects of arbitrary cross-sections is presented. Both the conductive boundary and internal material of the desired device is determined by the proposed formulation. The method is applicable to a wide range of waveguide, radiation, and cloaking problems, and is demonstrated for circular waveguide couplers and an external cloak. An advantage of the present method is that the material properties are simplified by appropriately selecting the conductive boundaries. For instance, a right-angle circular waveguide bend is presented which uses only one homogenous material. Also, transformation of conductive materials and boundaries are studied. The conditions in which the transformed boundaries remain conductive are discussed. In addition, it is demonstrated that negative infinite conductivity can be replaced with positive conductivity, without affecting the field outside the conductive boundary. It is also observed that a negative finite conductivity can be replaced with a positive one, by accepting some small errors. The general mathematical procedure and formulation for calculating the parametric surface equations of the conductive peripheries are presented.

Microstructure Evolution of Copper Strip during Continuous Extrusion and Rolling Forming

During the continuous extrusion and rolling forming process, the microstructure evolution of copper strip was investigated by the optical microscope and transmission electron microscope. The results indicated that the grains in the centre of as-cast rod billet were squashed in the clamping zone and were elongated in the rigid mobile zone. The fibrous structure formed in the upsetting zone. In the adhesion zone, the dynamic recrystallization occurred and the shear band was found. In the right-angle bending zone, the fibrous structure, recrystallized grains and shear bands existed together. The full dynamic recrystallization occurred in the extending extrusion zone. After continuous extrusion forming, the size of the grains of copper strip was larger than that in the extending extrusion zone. After rolling, the grains in copper strip were evidently stretched along the rolling direction, which resulted in the formation of stable direction. With the increase of rolling reduction, the grains were squashed gradually. When the rolling reduction increased from 2 to 6 mm, the tensile strength increased from 250 to 400 MPa, and the elongation decreased from 48% to 13%.

Surface-plasmonic right-angle waveguide amplifiers

We propose a surface-plasmonic right-angle bend waveguide with bismuth ion-doped glass film as core layer and Ag films as cladding layers for first time, to the best of our knowledge. Theoretical analysis shows that the right-angle has bend and absorption losses of 3.17 dB. The rate equations and power evolution equations of high concentration bismuth-doped glass film are setup and solved to analyze the effect of the waveguide length and active ion concentration on the signal gain and Noise Figure (NF). The theoretical results predict that with the pump power 100 mW, the active ion concentration 2.0×1026 ions/m3 and the right-angle waveguide size 1.0 cm×1.0 cm, small-signal unit-length net gain can reach 15.32 dB with NF less than 5.0 dB.

Investigations on Voids Formation in Cu–Mg Alloy During Continuous Extrusion

In this article, the microstructure evolution and the formation of void defects in continuous extruded Cu–Mg alloy were investigated. The results showed that hot deformation, grain rearrangement, grain rotation, and grain boundary sliding occurred in the right-angle bending zone and extending extrusion zone. Voids formed in the extending deformation zone and grew up in the extrusion deformation core. The uncoordinated reaction of the grain boundary and dislocation blocked grain boundary slide in the triple grain boundary junctions, leading to nucleation of voids. Severe deformation and grain rearrangement resulted in the expansion of voids consequently through with the grain boundary slide.