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An efficient scanning algorithm for improving accuracy based on minimising part warping in selected laser sintering process

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VIRTUAL AND PHYSICAL PROTOTYPING 2019年第1期14卷 59-78页

作者： Yeganeh, A. Manshoori Movahhedy, M. R. Khodaygan, S. Sharif Univ Technol Dept Mech Engn Azadi Ave Tehran Iran

In the selective laser sintering (SLS) method, layers of powder are scanned by a laser beam and sintered. The thermal gradients created by laser heating and the subsequent cooling of the sintered sections results in thermal stresses and part warping in the final part. Thermal gradients are dependent on the scanning algorithm, in particular, the scan vector length. In this work, an efficient scanning algorithm for the SLS process is presented with the aim to minimise the part warping in the final part due to thermally induced residual stresses, while maintaining the production time at a minimum. The proposed algorithm is implemented in a finite element simulation and scanning parameters including the number of offsets and scanning length are optimised at constant laser parameters and chamber conditions. The FE model is verified by testing a few samples on SLS machine and comparing the parts made by the proposed algorithm with those made using conventional scan algorithm is the same as parallel-line scan algorithm. It is shown that part warping in the parts made by the proposed algorithm is reduced by up to 35% while the production time, part accuracy and surface properties are improved.

关键词： Additive manufacturing selective laser sintering scanning algorithm hatching pattern part warping finite element modeling

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An automatic ordering method for streams in surface-water/groundwater interaction modeling

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HYDROGEOLOGY JOURNAL 2022年第6期30卷 1789-1800页

作者： Xu, Chengcheng Wu, Chu Li, Tianchen Lu, Chuiyu He, Xin Sun, Qingyan Qin, Tao Yan, Lingjia Anhui Univ Sci & Technol Sch Earth & Environm Huainan 232001 Peoples R China China Inst Water Resources & Hydropower Res State Key Lab Water Cycle Simulat & Regulat 1 Fuxing Rd Beijing 100038 Peoples R China

The widely used groundwater flow model MODFLOW offers a range of software packages to simulate the interaction between streams and groundwater in aquifer systems. However, these existing packages lack a general method to address the chaotic simulation sequences of stream segments and require these segments to be ordered by modelers as input to the code. Therefore, it is challenging to simulate a stream network divided into a large number of segments such as a canal irrigation system. In this study, the Streamflow Automatic Routing (SAR) package was developed, and an effective method is proposed to automatically determine the segment simulation sequence. The stream segment order in the SAR input file is arbitrary, which allows modifications of the stream network by removing segments directly and adding segments at the end of the segment group. This mainly includes two processes: scanning all the outlet channels of the water system and calling the recursive algorithm for each outlet channel of the water system. The SAR package was tested using a hypothetical stream-aquifer system and applied to a complex flow field in Aiding Lake of Turpan Basin, China. In the results, a close fitting between the simulation and observations shows that the SAR package precisely simulated the exchange flux between the steams and aquifer. The SAR package can significantly improve the efficiency of simulations in a complex stream network, and it can be widely used as a subroutine package of MODFLOW in agricultural irrigation areas where rivers and canals are interlaced.

关键词： Streamflow automatic routing Groundwater surface-water relations scanning algorithm Recursion algorithm MODFLOW

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Symmetric Non-Monochromatic Light as Reference in Fourier Transform Spectrometers

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APPLIED SPECTROSCOPY 2024年 37028241305415页

作者： Wen, Muqian Univ Limerick Bernal Inst Dept Phys Limerick V94T9PX Ireland

Fourier transform spectrometers typically use a presumed monochromatic reference source to track and correct errors in optical path difference changes. This paper will conduct a theoretical analysis to show that non-monochromatic light sources with symmetric spectral profiles can also be used as reference sources without adding errors. An experiment was carried out using a symmetric broadband superluminescent diode (SLED) as reference light to measure the spectrum of some other SLED light sources to experimentally demonstrate this finding.

关键词： Fourier transform spectroscopy continuous scan interferometer interferogram interferometer non-uniform sampling optical path difference OPD optics scanning algorithm zero-path difference

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Quartz tuning fork based three-dimensional topography imaging for sidewall with blind features

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ULTRAMICROSCOPY 2020年第0期210卷 112916-000页

作者： Akhtar, Imtisal Rehman, Malik Abdul Choi, Woosuk Bae, Joonho Seo, Yongho Sejong Univ Graphene Res Inst Seoul 05006 South Korea Sejong Univ Fac Nanotechnol & Adv Mat Engn Seoul 05006 South Korea Sejong Univ HMC Seoul 05006 South Korea Gachon Univ Dept Nanophys Seongnam Si 461701 South Korea

Atomic force microscopy has a tremendous number of applications in a wide variety of fields, particularly in the semiconductor area for the 3D-stacked device. Imaging three-dimensional (3D) structures with blind features has progressively become a critical technique. Recently, a 3D-atomic force microscopy (AFM) technique has been proposed to image 3D features, especially those having sharp apices, like silicon pillars. However, the scanning strategy has drawbacks, such as long scanning time, and unstable operation, based on the premature algorithm. Herein, an improved 3D-AFM algorithm is reported that overcomes the aforementioned problems by an intelligent 3D scanning algorithm that incorporates sidewall history tracking, troubleshooting for sharp sidewall and sticking, and reactive direction adjustment. The proposed algorithm enables the 3D imagery of ZnO nanorods and silicon nano-pillars to be achieved by using a high aspect-ratio multiwall carbon nanotube-based AFM probe, without time-consuming disorientation. This study establishes a method to construct a 3D image of arbitrary shape in reduced scanning time.

关键词： scanning probe microscopy scanning algorithm 3D topography Through silicon via Nanostructure imaging Sidewall imaging

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Generate Football News from Live Webcast Scripts Based on Character-CNN with Five Strokes

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电脑学刊 2020年第1期31卷 232-241页

作者： Xue-Qiang Lv Xin-Dong You Wen-Chao Wang Jian-She Zhou

Generating the football news from live webcast scripts is one kind of automatic text summarization in the field of natural language processing (NLP). Two typical characteristics in the live webcast scripts make the traditional methods can't well-generate the football news. Short sentences in live webcast scripts make it difficult to identify all of the keywords. And the sentence category identification is more crucial than the other kinds of automation text summarization. In this paper, the custom dictionary, forward dictionary and reverse dictionary in the football news domain are constructed, which aim to identify all import information from the live webcast. And the character-CNN with five strokes model is designed to classify the sentences category. Finally, the scanning algorithm based on time window is proposed to select the sentences to assemble into football news. Experiments results show that our designed Character-CNN model achieved higher accuracy rate on sentence classification than the state-of-art models. Evaluation conducted on ROUGE-1.5.5 toolkit showed that generating the football news with our proposed scanning algorithm outperforms than some baseline methods.

关键词： CNN Live Sports Text scanning algorithm Sports News

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RILS: RFID indoor localization system using mobile readers

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INTERNATIONAL JOURNAL OF DISTRIBUTED SENSOR NETWORKS 2018年第4期14卷

作者： Liu, Jinkai Qiu, Yanqing Yin, Kezhao Dong, Wentong Luo, Jiaqing Univ Elect Sci & Technol China Sch Comp Sci & Engn Chengdu 611731 Sichuan Peoples R China Sichuan Univ Chengdu Sichuan Peoples R China

The radio frequency identification technology was given greater interest as it is widely used for identification and localization in the cognitive radio sensor networks. While radio frequency identification-based indoor localization is attractive, the need for a large-scale and high-density deployment of readers and reference tags is costly. Using mobile readers mounted on guide rails, we design and implement an RFID indoor localization system, which requires neither reference tags nor received signal strength indicator functions, for stock-taking and searching in warehouse operations. In particular, we install two guide rails, which can allow a reader to move horizontally or vertically, on the ceiling of a warehouse or workshop. We then propose a continuous scanning algorithm to improve the accuracy for locating a single tagged object and a category-based scheduling algorithm to shorten the time for locating multiple tagged objects. Our primary experimental results show that RFID indoor localization system can achieve high time efficiency and localization accuracy in the indoor localization.

关键词： Radio frequency identification indoor localization mobile reader scanning algorithm category-based scheduling algorithm

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New SECM scanning algorithms for improved potentiometric imaging of circularly symmetric targets

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ELECTROCHIMICA ACTA 2014年 119卷 169-174页

作者： Kiss, Andras Nagy, Geza Univ Pecs Fac Sci Dept Gen & Phys Chem H-7624 Pecs Hungary Univ Pecs Janos Szentagothai Res Ctr H-7624 Pecs Hungary

To obtain high quality images in scanning probe microscopy (SPM), a certain amount of scanning time is required, depending on the number of sampling points, and the scanning speed. Usually, there is a compromise between scanning speed and image quality. This is most critical in the potentiometric scanning electrochemical microscopy (SECM), which is severely limited by the relatively long response time of the ultramicro-electrode probes. That is, scanning speed can be increased only at the expense of image quality. In a great majority of the SECM studies, the subjects are circularly symmetric systems. In this paper, we present a method to increase SECM imaging speed of such systems, while improving image quality at the same time. It is achieved by using new, polar coordinate-based scanning patterns, exploiting the symmetry of the studied system, and using imaging time more economically. This technique, combined with our previously reported simplex algorithm for automatic target location, significantly improves the imaging of circularly symmetric targets. Numerical simulations and SECM scans using the traditional, and the new scanning algorithms have been performed. The resulting images have been compared with the expected, ideal image. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： scanning electrochemical microscope Potentiometry Response time scanning algorithm

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Feature-based surrogates for low-cost microwave modelling and optimisation

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IET MICROWAVES ANTENNAS & PROPAGATION 2015年第15期9卷 1706-1712页

作者： Koziel, Slawomir Cheng, Qingsha S. Bandler, John W. Reykjavik Univ Engn Optimizat & Modeling Ctr IS-101 Reykjavik Iceland SUSTC Dept Elect & Elect Engn Shenzhen 518055 Guangdong Peoples R China McMaster Univ Dept Elect & Comp Engn Hamilton ON L8S 4K1 Canada Bandler Corp Dundas ON L9H 5E7 Canada

A simple, reliable, and accurate surrogate modelling technique for microwave structures is presented. A hierarchical surrogate model is constructed using response surface approximations (RSAs) of suitable response features with embedded visible' knowledge. The authors describe and discuss a novel scanning algorithm for capturing these desired response features. They demonstrate that the dependence of the selected features on the designable parameters is much less non-linear than that of the original responses taken as functions of the design parameters. They illustrate the steps of their algorithm using novel diagrams. They simplify the description of their modelling process by exploiting an operator notation. They discuss relationships between their method and other feature-based approaches such as shape-preserving response prediction (SPRP). They provide a wideband microstrip bandstop filter, a fourth-order ring resonator bandpass filter and a microstrip bandpass filter with open stub inverter examples to demonstrate their approach. Using these examples, they compare their approach with two very different direct RSA methods (kriging and radial basis function) and an SPRP method. The models of all the filter examples are validated using design optimisation.

关键词： response surface methodology microstrip filters band-pass filters resonator filters band-stop filters microwave filters approximation theory feature-based surrogate approach microwave modelling microwave structure hierarchical surrogate model response surface approximation RSA method scanning algorithm design parameters modelling process wideband microstrip bandstop filter ring resonator bandpass filter microstrip bandpass filter SPRP method

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EFFICIENT 2×2 BLOCK-BASED CONNECTED COMPONENTS LABELING algorithmS

EFFICIENT 2×2 BLOCK-BASED CONNECTED COMPONENTS LABELING ALG...

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IEEE International Conference on Image Processing

作者： Diego J. C. Santiago Tsang Ing Ren George D. C. Cavalcanti Tsang Ing Jyh Center for Informatics Federal University of Pernambuco Alcatel-Lucent

ISBN: (纸本)9781479983407

This paper presents three new efficient 2×2 block-based algorithms for connected components labeling: a two-scan which assigns provisional labels to blocks, a two-scan which assigns provisional labels to pixels and a one-and-a-half-scan which assigns provisional labels to blocks. A new stripe image representation is designed in order to perform the second pass only through the blocks containing some foreground pixel. We also improved the existing 2×2 block-based algorithms by utilizing information of a pixel during a transition in the mask, which allows checking of four neighbor pixels in the mask at most. Thus, the average number of checking operations needed to inspect the neighbor pixels in the first scan is reduced from 1.459 to 1.156, an improvement of 21%. We conducted experiments using synthetic and real images to evaluate the performance of the proposed methods compared to the existing methods. The proposed block-based one-and-a-half-scan algorithm presents the best performance in the real images dataset, which is composed of 1290 documents. Our block-based two-scan algorithm which assigns provisional labels to pixels showed to be the fastest in the synthetic dataset, especially in high density images.

关键词： Connected components labeling Block-based One-and-a-half-scan Image processing Image analysis pixel connected component Image processing image analysis algorithms Masks scanning algorithm

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Impact of Incomplete Knowledge on scanning Strategy

Impact of Incomplete Knowledge on Scanning Strategy

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IEEE International Workshop on Information Forensics and Security

作者： Andrey Garnaev Wade Trappe WINLAB Rutgers University

ISBN: (纸本)9781467368032

Security is a fundamental problem facing wire-less systems employing spectrum sharing, and thus scanning algorithms are used to detect malicious or illegal activity in such systems. A crucial issue in designing such algorithms is incorporating knowledge about the environment, as well as what knowledge an adversary might have, into the scanning algorithm to improve detection performance. In particular, if such knowledge is initially incomplete, it becomes desirable to adapt one's knowledge based upon the results of the scanning activities, so as to further improve detection performance. To obtain insight into this problem, we suggest a Bayesian game-theoretical model of bandwidth scanning with learning. We show that such knowledge could change the structure of the strategies employed from distributing effort among all the bands, to band-sharing or even band on/off strategies and improve detection performance. Also, we have shown that a lack of information for the scanner compare to the adversary makes the scanner strategy more sensitive to the information he has.

关键词： scanning scanning algorithm Incomplete knowledge Scanner Epistemology

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