Electric Control of Friction on Silicon Studied by Atomic Force Microscope

Yan Jiang,Lili Yue,Boshen Yan,Xi Liu,Xiaofei Yang,Guoan Tai,Juan Song 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.3

We investigated friction on an n-type silicon surface using an atomic force microscope when a bias voltage was applied to the sample. Friction forces on the same track line were measured before and after the bias voltages were applied and it was found that the friction forces in n-type silicon can be tuned reversibly with the bias voltage. The dependence of adhesion forces between the silicon nitride tip and Si sample on the bias voltages approximately follows a parabolic law due to electrostatic force, which results in a significant increase in the friction force at an applied electric field.

Segmented Douglas-Peucker Algorithm Based on the Node Importance

( Xiaofei Wang ),( Wei Yang ),( Yan Liu ),( Rui Sun ),( Jun Hu ),( Longcheng Yang ),( Boyang Hou ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.4

Vector data compression algorithm can meet requirements of different levels and scales by reducing the data amount of vector graphics, so as to reduce the transmission, processing time and storage overhead of data. In view of the fact that large threshold leading to comparatively large error in Douglas-Peucker vector data compression algorithm, which has difficulty in maintaining the uncertainty of shape features and threshold selection, a segmented Douglas-Peucker algorithm based on node importance is proposed. Firstly, the algorithm uses the vertical chord ratio as the main feature to detect and extract the critical points with large contribution to the shape of the curve, so as to ensure its basic shape. Then, combined with the radial distance constraint, it selects the maximum point as the critical point, and introduces the threshold related to the scale to merge and adjust the critical points, so as to realize local feature extraction between two critical points to meet the requirements in accuracy. Finally, through a large number of different vector data sets, the improved algorithm is analyzed and evaluated from qualitative and quantitative aspects. Experimental results indicate that the improved vector data compression algorithm is better than Douglas-Peucker algorithm in shape retention, compression error, results simplification and time efficiency.

Investigation on Low-Frequency Sound Absorption Properties of PVB Micro-/Nanofiber Membranes

Xiaofei Shao,Jiahui Shen,Xiong Yan 한국섬유공학회 2023 Fibers and polymers Vol.24 No.8

In this study, polyvinyl butyral (PVB) was used as raw material, combined with electrospinning and microperforation process to prepare micro-/nanofiber membranes with excellent low-frequency sound absorption performance. To comprehensively explore the influence mechanisms of fiber diameter, multi-layer structure, and microperforated structure on the sound absorption performance, experiment and theoretical analysis were both conducted. Experimental results showed that appropriately reducing the fiber diameter, increasing the number of PVB membrane layers, and setting microperforated structure and cavity could improve the sound absorption performance in the low-frequency range. By adjusting the number of layers and the microperforation structure, the effective sound absorption band range of the fiber membrane can also be adjusted to better meet the sound absorption requirements. When the number of fiber layers was 20, the perforation rate was 1%, the perforation diameter was 0.6 mm, and the cavity depth was 40 mm, the PVB fiber membrane had peaks of 0.8483 and 0.9792 at 350 Hz and 480 Hz, respectively. Theoretical analysis showed that the acoustic electrical analogy model can well predict the resonance frequency and sound absorption peak of fiber membrane, and proved that microporous fiber membrane had both porous and resonant sound absorption mechanisms. These lightweight fiber membranes have great potential for application in sound absorption, such as in transportation, construction, and instrumentation.

Research on Embedded Network Real-Time Video Monitoring System Based on Zynq

Yang Nie,Xiaofei Yin,Yu Hu,Hanbin Xu,Ruofei Yan 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.11

With the improvement of the performance of the embedded processor, the real-time network video monitoring system based on embedded technology becomes a developing direction of the network video with its low price and portability. In this paper, software and hardware co-design method is adopted to design an embedded system. ARM of the Zynq chip is responsible for embedded system structures and high definition video processing, and FPGA is used to design other logic and hardware expansion. Compared with the traditional network video monitoring technology, the embedded network video monitoring technology based on Zynq not only improves the quality of the image, but also has better real-time performance and scalability.

An automatic detection method for lung nodules based on multi-scale enhancement filters and 3D shape features

( Rui Hao ),( Yan Qiang ),( Xiaolei Liao ),( Xiaofei Yan ),( Guohua Ji ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.1

In the computer-aided detection (CAD) system of pulmonary nodules, a high false positive rate is common because the density and the computed tomography (CT) values of the vessel and the nodule in the CT images are similar, which affects the detection accuracy of pulmonary nodules. In this paper, a method of automatic detection of pulmonary nodules based on multi-scale enhancement filters and 3D shape features is proposed. The method uses an iterative threshold and a region growing algorithm to segment lung parenchyma. Two types of multi-scale enhancement filters are constructed to enhance the images of nodules and blood vessels in 3D lung images, and most of the blood vessel images in the nodular images are removed to obtain a suspected nodule image. An 18 neighborhood region growing algorithm is then used to extract the lung nodules. A new pulmonary nodules feature descriptor is proposed, and the features of the suspected nodules are extracted. A support vector machine (SVM) classifier is used to classify the pulmonary nodules. The experimental results show that our method can effectively detect pulmonary nodules and reduce false positive rates, and the feature descriptor proposed in this paper is valid which can be used to distinguish between nodules and blood vessels.

Methodology and software to detect viral integration site hot-spots

Presson, Angela P,Kim, Namshin,Xiaofei, Yan,Chen, Irvin SY,Kim, Sanggu BioMed Central 2011 BMC bioinformatics Vol.12 No.-

<P><B>Background</B></P><P>Modern gene therapy methods have limited control over where a therapeutic viral vector inserts into the host genome. Vector integration can activate local gene expression, which can cause cancer if the vector inserts near an oncogene. Viral integration hot-spots or 'common insertion sites' (CIS) are scrutinized to evaluate and predict patient safety. CIS are typically defined by a minimum density of insertions (such as 2-4 within a 30-100 kb region), which unfortunately depends on the total number of observed VIS. This is problematic for comparing hot-spot distributions across data sets and patients, where the VIS numbers may vary.</P><P><B>Results</B></P><P>We develop two new methods for defining hot-spots that are relatively independent of data set size. Both methods operate on distributions of VIS across consecutive 1 Mb 'bins' of the genome. The first method 'z-threshold' tallies the number of VIS per bin, converts these counts to z-scores, and applies a threshold to define high density bins. The second method 'BCP' applies a Bayesian change-point model to the z-scores to define hot-spots. The novel hot-spot methods are compared with a conventional CIS method using simulated data sets and data sets from five published human studies, including the X-linked ALD (adrenoleukodystrophy), CGD (chronic granulomatous disease) and SCID-X1 (X-linked severe combined immunodeficiency) trials. The BCP analysis of the human X-linked ALD data for two patients separately (774 and 1627 VIS) and combined (2401 VIS) resulted in 5-6 hot-spots covering 0.17-0.251% of the genome and containing 5.56-7.74% of the total VIS. In comparison, the CIS analysis resulted in 12-110 hot-spots covering 0.018-0.246% of the genome and containing 5.81-22.7% of the VIS, corresponding to a greater number of hot-spots as the data set size increased. Our hot-spot methods enable one to evaluate the extent of VIS clustering, and formally compare data sets in terms of hot-spot overlap. Finally, we show that the BCP hot-spots from the repopulating samples coincide with greater gene and CpG island density than the median genome density.</P><P><B>Conclusions</B></P><P>The z-threshold and BCP methods are useful for comparing hot-spot patterns across data sets of disparate sizes. The methodology and software provided here should enable one to study hot-spot conservation across a variety of VIS data sets and evaluate vector safety for gene therapy trials.</P>

Dirac semimetal-enabled multi-bit coding metasurface for dynamic manipulation of terahertz beams

Zhang Yonggang,Yin Kehao,Liang Lanju,Yao Haiyun,Yan Xin,Hu Xiaofei,Huang Chengcheng,Qiu Fu,Zhang Rui,Li Yuanping,Wang Yaru,Li Zhenhua,Wang Ziqun 한국물리학회 2024 Current Applied Physics Vol.58 No.-

In this study, a switchable multi-bit coding metasurface that is applied under a terahertz (THz) frequency by adjusting the Fermi level (EF) of Dirac semimetals (DSMs) is proposed. At a EF of 0.2 eV, a 1-bit coding metasurface can be applied in the 2.58–2.62 THz. At 0.3 eV, a 3-bit coding metasurface is realized at 1.88 THz, and at 0.05 eV, the phase of the coding units coincides in the 1.5–3 THz. So, different functions of the metasurface can be realized. The proposed coding metasurfaces has promising applications in terahertz communication.