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Influence of Torsion on the Laminar Flow and Convective Heat Transfer in Coiled Tubes Arranged in a rectangular pattern

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HEAT TRANSFER RESEARCH 2010年第5期41卷 493-508页

作者： Conte, I. Peng, X. -F. Campo, A. Univ Texas San Antonio Coll Engn Dept Mech Engn San Antonio TX 78249 USA Tsinghua Univ Dept Thermal Engn Lab Phase Change & Interfacial Transport Phenomen Beijing 100084 Peoples R China

A detailed numerical investigation has been undertaken to understand the intricacies of laminar forced flows with convective heat transfer inside coiled tubes of circular cross section. The coiled tubes consist of two straight parts and two bends which are arranged in a rectangular pattern. The laminar flows are characterized by three different Reynolds numbers: Re = 300, 700, and 1400. Computer simulations to calculate the laminar velocity and temperature fields were performed for four coiled tubes having different bend torsion ratios. Compared to the coiled tubes near the entrance of the first bend, the rotation experienced by the fluid motion due to torsion is less significant in the second bend. This behavior is attributable to the flow redevelopment in the upstream straight tube. The numerical results demonstrate a vigorous fluid rotation for flows possessing higher velocities whose magnitudes are given by Re = 700 and 1400. The flow path in the bend is representative of a typical flow near the entrance region of a helically coiled tube. The numerical predictions agree well with those results generated by numerical computations and experimental observations. Overall, the heat transfer coefficient decreases with increments in the bend torsion;this behavior is caused primarily by the weakening in the secondary flows.

关键词： laminar flow forced convection coiled tube rectangular pattern curvature torsion

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Analytical solution for soil flushing using PVD system with rectangular pattern

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GEOSYNTHETICS INTERNATIONAL 2023年第3期30卷 274-284页

作者： Zhou, X. Wang, H-Y Ling, D-S Liu, W. Ke, H. Zhejiang Univ Inst Geotech Engn Hangzhou Peoples R China NingboTech Univ Sch Civil Engn & Architecture Ningbo Peoples R China Soochow Univ Sch Rail Transportat Suzhou Peoples R China

Soil flushing using prefabricated vertical drains (PVDs) is an innovative subsurface remediation technology for contaminated fine-grained soils. An analytical solution is presented to investigate the performance of a PVD-enhanced system arranged in a rectangular pattern for soil remediation. The analytical solution is derived based on a simplified equivalent model in which PVDs are substituted by drain walls. The results of the analytical solution are shown to be roughly consistent with those obtained from the finite-element method. Using the proposed solution, the remediation efficiency for a rectangular layout is demonstrated to be higher than that for a parallel layout. Furthermore, the effects of distance between injection and extraction PVD, injection rate, distribution coefficient, and dispersivity are investigated. Results indicate that a square pattern is the optimal layout of PVDs compared to other rectangular patterns. Increasing the injection rate of individual PVDs is an effective way to improve the remediation efficiency. The increase of distribution coefficient of contaminant leads to a significant increase in the remediation time, and the increase of longitudinal and transverse dispersivity results in a more uniform spatial distribution of contaminant concentration during the flushing process.

关键词： Geosynthetics soil flushing PVD-enhanced system rectangular pattern analytical solution

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rectangular drainage pattern evolution controlled by pipe cave collapse along clastic dikes, the Dead Sea Basin, Israel

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EARTH SURFACE PROCESSES AND LANDFORMS 2022年第4期47卷 936-954页

作者： Hamawi, Matanya Goren, Liran Mushkin, Amit Levi, Tsafrir Ben Gurion Univ Negev Dept Earth & Environm Sci IL-8410501 Beer Sheva Israel Geol Survey Israel Jerusalem Israel

rectangular drainage networks are characterized by right-angle bends and confluences. The formation of such drainage patterns is commonly associated with orthogonal sets of fractures, making them an outstanding example for structurally controlled landscape evolution. However, this association remains largely circumstantial because little is known about how rectangular drainages mechanistically link to orthogonal fractures. We investigated these linkages in the hyper-arid Ami'az Plain located within the Dead Sea Basin in Israel. The Ami'az Plain is penetrated by hundreds of sub-vertical clastic dikes (mode-I fractures infilled with sediments) and is also incised by a rectangular canyon system. Numerous caves extend from the banks and heads of the canyon system. Based on field surveys and analysis of high-resolution airborne LiDAR data, we mapped the Ami'az Plain drainage network and its associated landforms, including sinkholes. Our analysis revealed that the subaerial tributaries of the canyon system and the strike of the clastic dikes show similar orientations. In addition, subsurface mapping with a ground-based scanning LiDAR, together with field experiments, demonstrated that the caves and sinkholes in the Ami'az Plain are spatially associated with clastic dikes and that the caves formed through piping erosion along dikes. Based on these findings, we suggest that clastic dikes act as efficient infiltration pathways to the subsurface, where flow along clastic dikes induces internal erosion that forms pipe caves. The sinkholes form by collapses of cave roofs. Coalescence of sinkholes and seepage erosion where dikes intersect canyon heads generate new tributaries and act to extend existing ones. Fluvial erosion and subsequent bank collapse modify the canyon network. Our findings emphasize the critical role of subsurface erosion, caves and sinkholes in linking fractures to drainage pattern evolution, and provide a new process-based framework to interpret rectangular

关键词： clastic dikes Dead Sea drainage pattern hyper-arid internal erosion piping caves piping erosion rectangular pattern seepage erosion sinkholes

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Fidelity of rectangular patterns printed with 0.3-NA MET optics

Fidelity of rectangular patterns printed with 0.3-NA MET opt...

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Conference on Emerging Lithographic Technologies XI

作者： Tanaka, Yuusuke Kikuchi, Yukiko Goo, DooHoon Nishiyama, Iwao Assoc Super Adv Elect Technologies NTT Atsugi R&D Ctr EUV Proc Technol Res Lab 3-1 Morinosato Wakamiya Atsugi Kanagawa 243 Japan

ISBN: (纸本)9780819466365

Arrays of rectangular patterns of various sizes were printed with the EUV micro-exposure tool (MET) at the Lawrence Berkeley National Laboratory (LBNL) using the chemically-amplified resist MET-1K;and their fidelity to the mask patterns was evaluated. The experimental results showed that the shortening of resist patterns in the lengthwise direction was greater for smaller patterns. For example, the line-end shortening of half-pitch (hp) 45-m patterns was about 20-25 nm on one side, while that of hp-90-nm patterns was less than 10 nm. However, simulated aerial images exhibited little shortening, even for hp-45-nm patterns. On the other hand, considerable shortening appeared in hp-45-nm patterns after post-exposure-baking (PEB) process. When the acid diffusion length in the PEB process was assumed to be 20 nm, the calculated shapes of resist patterns agreed well with the experimental results for various sizes. Printing experiments showed that lowering the PEB temperature improved fidelity, probably due to the shorter acid diffusion length. Thus, we concluded that acid diffusion is the main cause of shortening in rectangular patterns printed with the MET. For better pattern fidelity, the acid diffusion length must be reduced in accordance with the reduction in pattern size.

关键词： EUVL fidelity MET resist rectangular pattern shortening acid diffusion length PEB MET-1K

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Adaptive scanning methodology for object-oriented visual information processing

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ELECTRONICS LETTERS 2013年第10期49卷 651-652页

作者： Chew, Li Wern Intel Microelect M Intel Architecture Grp George Town 11900 Malaysia

The raster scan method in visual information processing is the rectangular pattern of image capture and reconstruction which systematically covers the area progressively, one line at a time starting from the top left corner. This traditional scanning method might work well for still image processing but for moving images, a scanning method such as diagonal snake scan can provide a better object correlation in a sequence of image frames. A novel adaptive scanning method for object-oriented visual information processing is proposed. Here, image pixels are collected starting from the centre of the image area and progressively extended outwards similar to the water drop ripple effect. Simulation results have shown that the proposed work uses up to 33% less processing time to cover the region-of-interest in an image compared to the raster scan method. Preliminary simulation results have also shown that with the proposed adaptive scanning methodology, there is a significant improvement in the performance of the object-oriented visual compression.

关键词： image capture object correlation image pixels adaptive scanning methodology image frames adaptive scanning method Object-oriented programming water drop ripple effect raster scan method image processing rectangular pattern Computer vision and image processing techniques object-oriented programming image reconstruction Optical, image and video signal processing object-oriented visual information processing ROI diagonal snake region-of-interest object detection

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Reduction of image shortening in two-dimensional pattern replication using X-ray lithography

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 1998年第12B期37卷 6836-6840页

作者： Nakanishi, K Deguchi, K Matsuda, T Oda, N NTT Syst Elect Labs Atsugi Kanagawa 24430198 Japan

Image shortening cannot be ignored in sub-100-nm pattern replication using X-ray lithography. It is important to know whether or not optical proximity correction is necessary for the reduction of image shortening. The authors investigated the image shortening of a rectangular pattern, and its reduction by adding a serif or mask bias. By adding a serif, image shortening was reduced dramatically, but critical dimension control of the resist pattern ends was degraded. On the other hand, image shortening for an ideal rectangular pattern was expected to be lower than 50'% of the designed spacing, and can easily be canceled out with just a mask bias. This means that the use of a serif is not necessary, and a mask bias is more effective in reducing image shortening in X-ray lithography.

关键词： X-ray lithography SR lithography image shortening rectangular pattern serif pattern low-contrast mask chemically amplified resist

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Experimental Investigation on the Radiation pattern of a Horn Antenna Loaded by a Wire Medium

Experimental Investigation on the Radiation Pattern of a Hor...

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IEEE International Symposium on Antennas and Propagation

作者： Antonio Tomaz Joaquim J. Barroso P. J. Castro Alberto J. Faro Orlando Aeronautics Technological Institute (ITA) National Institute for Space Research (INPE)

ISBN: (纸本)9781467353168

The present paper reports on the design, implementation, and tests of a wire medium to experimentally verify its effects on the performance of a standard X-band horn antenna loaded by such a bulk metamaterial medium. The wire medium is composed of a periodic array of 0.5-mm-diameter metallic wires arranged in a square pattern with lattice spacing of 10.0 mm and hosted in Styrofoam plates. Experimental measurements of the radiation pattern at 11.70 GHz show an enhancement of the side lobes while maintaining the antenna peak gain, indicating that the metamaterial wire medium introduces negligible loss into the loaded antenna.

关键词： Radiation patterns horn antennas Loaded antennas rectangular pattern Polystyrene foams left-handed materials

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Effect of oxygen plasma treatment and gold sputtering on morphological and local mechanical properties of copolyimide/gold micropatterned structures

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SURFACE AND INTERFACE ANALYSIS 2018年第2期50卷 154-162页

作者： Stoica, Iuliana Aflori, Magdalena Ioanid, Emil Ghiocel Hulubei, Camelia Petru Poni Inst Macromol Chem Dept Polymer Mat Phys Iasi 700487 Romania Univ Politehn Bucuresti Fac Appl Chem & Mat Sci Dept Bioresources & Polymer Sci Bucharest 011061 Romania Petru Poni Inst Macromol Chem Dept Polycondensat & Thermostable Polymers Iasi 700487 Romania

Atomic force microscopy (AFM) was used to analyze rectangular 3-dimensional patterned microstructures with different functionalities induced on copolyimide containing alicyclic sequences film surfaces by means of oxygen plasma treatment. The plasma power was ranged to be big enough to accelerate the plasma species towards the copolyimide surface, and the exposure time was not very small to generate a roughness that still can be monitored by AFM. To create the rectangular pattern, transmission electron microscopy grid masks were placed on the samples before treatment. Plasma-induced micropatterning with alternating hydrophilic and hydrophobic surface chemistries was evaluated by measuring the adhesion forces between the gold-covered AFM tip and the copolyimide surfaces. To fabricate 3-dimensional metallic microstructures arranged in well-defined areas, thin metal layers were sputtered on these pretreated copolyimide films. The AFM morphological aspects of the obtained metallic structures were correlated with the surface modifications induced by plasma treatment conditions. Functional indexes and functional volume parameters were also calculate to characterize the functional behavior of the surface, such as wear, lubrication, and contact. The AFM data were compared with those obtained using the small-angle X-ray scattering measurements.

关键词： adhesion AFM analysis gold sputtering oxygen plasma rectangular pattern SAXS analysis

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