Loosely-bound low-loss surface plasmons in hyperbolic metamaterial

Shi Yu,Kim Hong Koo 나노기술연구협의회 2018 Nano Convergence Vol.5 No.16

Surface plasmons (SPs) carry electromagnetic energy in the form of collective oscillation of electrons at metal surface and commonly demonstrate two important features: strong lateral confinement and short propagation lengths. In this work we have investigated the trade-off relationship existing between propagation length and lateral confinement of SP fields in a hyperbolic metamaterial system, and explored loosening of lateral confinement as a means of increasing propagation length. By performing finite-difference time-domain analysis of Ag/SiO2 thin-film stacked structure we demonstrate long range (~ 100 mm) propagation of SPs at 1.3 µm wavelength. In designing low-loss loosely-bound SPs, our approach is to maximally deplete electric fields (both tangential and normal components to the interface) inside metal layers and to support SP fields primarily in the dielectric layers part of metamaterial. Such highly-localized field distributions are attained in a hyperbolic metamaterial structure, whose dielectric tensor is designed to be highly anisotropic, that is, low-loss dielectric (Re(ε) > 0; Im(ε) ~ 0) along the transverse direction (i.e., normal to the interface) and metallic (large negative Re(ε)) along the longitudinal direction, and by closely matching external dielectric to the normal component of metamaterial’s dielectric tensor. Suppressing the tangential component of electric field is shown to naturally result in weakly-confined SPs with penetration depths in the range of 3–10 µm. An effective-medium approximation method is used in designing the metamaterial waveguide structure, and we have tested its validity in applying to a minimally structured core-layer case (i.e., composed of one or two metal layers). Low-loss loosely-bound SPs may find alternative applications in far-field evanescent-wave sensing and optics.

A QEE-Oriented Fair Power Allocation for Two-tier Heterogeneous Networks

( Shiyu Ji ),( Liangrui Tang ),( Yanhua He ),( Shuxian Li ),( Shimo Du ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.5

In future wireless network, user experience and energy efficiency will play more and more important roles in the communication systems compared to their roles at present. Quality of experience (QoE) and Energy Efficiency (EE) become the widely used metrics. In this paper, we study a combinatorial problem of QoE and EE and investigate a fair power allocation in heterogeneous networks. We first design a new metric, QoE-aware EE (QEE) to reflect the relationship of QoE and energy. Then, the concept of Utopia QEE is introduced, which is defined as the achievable maximum QEE in ideal conditions, for each user. Finally, we transform the power allocation process to an optimization of ratio of QEE and Utopia QEE and use invasive weed optimization (IWO) algorithm to solve the optimization problem. Numerical simulation results indicate that the proposed algorithm can get converged and efficiently improve the system energy efficiency and the QoE for each user.

Facile Fabrication of Superhydrophobic Nanocellulose Films via Covalent Layer-by-Layer Assembled

Shiyu Fu,Chenghua Yu,Feng Wang 한국펄프·종이공학회 2016 한국펄프·종이공학회 학술발표논문집 Vol.2016 No.10

Association between perioperative glucocorticoids and cancer metastasis and survival in patients undergoing radical cystectomy for urothelial carcinoma of the bladder: A single-center retrospective study

Shiyu Mao,Yuan Wu,Ruiliang Wang,Yadong Guo,Jing Yuan,Wentao Zhang,Junfeng Zhang,Yang Yan,Xudong Yao 대한비뇨의학회 2020 Investigative and Clinical Urology Vol.61 No.4

Purpose: Perioperative glucocorticoids have the potential to increase the risk of tumor metastasis. However, the relationship between perioperative glucocorticoids and oncologic outcomes remains controversial. The present study was undertaken to evaluate the association of perioperative glucocorticoids with clinicopathologic outcomes following radical cystectomy (RC). Materials and Methods: We screened and included 185 patients who underwent radical surgery for bladder cancer in our center between 2009 and 2018. The Kaplan–Meier method was applied, and a log-rank test was used to estimate differences in metastasis-free survival (MFS) and overall survival (OS) between the groups. Multivariate Cox proportional hazards regression models were used to analyze any association of glucocorticoids with clinical outcomes. Results: A total of 76 (41.1%) patients received perioperative glucocorticoids. Median postoperative follow-up was 2.0 years. Kaplan–Meier survival curve indicated that the glucocorticoids group was significantly associated with increased distant MFS (p=0.008) but not with OS. In the multivariate analysis, no significant differences were observed for MFS between the groups. Interestingly, when the variable of blood transfusion was excluded from the multivariate analysis model, we found that patients receiving glucocorticoids were independently associated with worse MFS (hazard ratio, 1.790; p=0.030). Furthermore, the partial correlation analysis showed a significant positive correlation between perioperative glucocorticoids and blood transfusion (r=0.604, p<0.001). In the nontransfusion subgroup, propensity score matching showed that patients receiving glucocorticoids had a higher risk of distant metastasis. Conclusions: Perioperative glucocorticoids were associated with a higher rate of distant metastasis in patients undergoing RC for bladder cancer.

Cloning and characterization of hexamerin in Spodoptera exigua and the expression response to insecticide exposure

Shiyu Wang,Bo Hu,Qi Wei,Jianya Su 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.2

Hexamerins are hemolymph-proteins, which are mainly considered as storage proteins for non-feeding stages, and also undertake other roles during insect development and growth, however the characterization of hexamerin proteins in Spodoptera exigua is less understood. In this study five new hexamerin genes were identified and a total seven hexamerin genes were reported in S. exigua. These hexamerins contain the typical domains of hemocyanin at the N-terminal, C-terminal and in the middle of their protein sequences. These genes are mainly expressed in fat body, and the signal peptide sequences at their N-terminal of protein sequences can drive the expressed protein to excrete into hemolymph after synthesis. The phylogenetic analysis and amine acid composition revealed S. exigua express five different types of hexamerins: 1) Storage protein rich in methionine residue (MRSP), 2) Storage protein moderately rich in methionine (MMRSP), 3) Hexamerin with high composition of aromatic amino acids (Arylphorin), 4) Arylphorin-like hexamerin, and 5) Riboflavin-binding hexamerin (RbH). The phylogenetic pattern combined with the comparison of conserved histidine residues in copper binding sites of hexamerins revealed basal position of RbH and the evolutionary pathway in lepidopteran hexamerins. Finally, the induction expression of hexamerins by insecticide, lambda-cyhalothrin, were analyzed, results showed that lambda-cyhalothrin exposure may down-regulate their expression. This study increased the gene number of hexamerin to seven, and reported their expression and structural characterizations, the finding will facilitate the understand of hexamerin in other insects.

Research on data augmentation algorithm for time series based on deep learning

Shiyu Liu,Hongyan Qiao,Lianhong Yuan,Yuan Yuan,Jun Liu 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.6

Data monitoring is an important foundation of modern science. In most cases, the monitoring data is time-series data, which has high application value. The deep learning algorithm has a strong nonlinear fitting capability, which enables the recognition of time series by capturing anomalous information in time series. At present, the research of time series recognition based on deep learning is especially important for data monitoring. Deep learning algorithms require a large amount of data for training. However, abnormal sample is a small sample in time series, which means the number of abnormal time series can seriously affect the accuracy of recognition algorithm because of class imbalance. In order to increase the number of abnormal sample, a data augmentation method called GANBATS (GAN-based Bi-LSTM and Attention for Time Series) is proposed. In GANBATS, Bi-LSTM is introduced to extract the timing features and then transfer features to the generator network of GANBATS.GANBATS also modifies the discriminator network by adding an attention mechanism to achieve global attention for time series. At the end of discriminator, GANBATS is adding averagepooling layer, which merges temporal features to boost the operational efficiency. In this paper, four time series datasets and five data augmentation algorithms are used for comparison experiments. The generated data are measured by PRD(Percent Root Mean Square Difference) and DTW(Dynamic Time Warping). The experimental results show that GANBATS reduces up to 26.22 in PRD metric and 9.45 in DTW metric. In addition, this paper uses different algorithms to reconstruct the datasets and compare them by classification accuracy. The classification accuracy is improved by 6.44%-12.96% on four time series datasets.

Application of Travel Management System Based on Route Inquiry

Shiyu Wang,Liwei Chen 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.6

The traditional tourism system’s information inquiry is incomplete, images are not intuitive and the results are not three-dimensional. In order to solve these problems, this paper proposes system management design and application based on tourist routes inquiry. Firstly, based on MAP technology, it achieves a cross-check of space and attribute data, then explores the knapsack problem through the genetic algorithm, making the travel route arrangements more reasonable and providing latest shareable maps for tourists, and finally conducts simulation experiment on system model. The results show that compared with the traditional one, this tourism management system’s information inquiry is faster, and also its inquiry results are more three-dimensional and visual. It is much more convenient for tourists with practicality.

An Improved Result on Stability Analysis of Delayed Load Frequency Control Power Systems

Shiyu Jiao,Jianwei Xia,Zhen Wang,Xiangyong Chen,Jing Wang,Hao Shen 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.4

This paper investigates the stability of power systems with load frequency control considering time delays(constant and time-varying delays). A new criterion for ensuring the stability of the system is proposed on the basisof Lyapunov stability theory and a further strengthened inequality. Finally, taking a single-area load frequencycontrol scheme with the proportional-integral controller as an example, according to the stability criterion obtained,the relationship between the maximum allowable delay and the gain of proportional-integral controller is discussed. Besides, in case studies, the effectiveness of our method is also demonstrated.

QoE-aware Energy Efficiency Maximization Based Joint User Access Selection and Power Allocation for Heterogeneous Network

( Shiyu Ji ),( Liangrui Tang ),( Chen Xu ),( Shimo Du ),( Jiajia Zhu ),( Hailin Hu ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.10

In future, since the user experience plays a more and more important role in the development of today’s communication systems, quality of experience (QoE) becomes a widely used metric, which reflects the subjective experience of end users for wireless service. In addition, the energy efficiency is an increasingly important problem with the explosive growth in the amount of wireless terminals and nodes. Hence, a QoE-aware energy efficiency maximization based joint user access selection and power allocation approach is proposed to solve the problem. We transform the joint allocation process to an optimization of energy efficiency by establishing an energy efficiency model, and then the optimization problem is solved by chaotic clone immune algorithm (CCIA). Numerical simulation results indicate that the proposed algorithm can efficiently and reliably improve the QoE and ensure high energy efficiency of networks.

Tuning Molecular Composition for Better Cross-section Homogeneity of Thermal Oxidative Stabilized Polyacrylonitrile for Carbon Materials

Shiyu Liu,Yuan Ge,Baijun Liu,Zhongyu Fu,Xiaoyu Yu,Ming Yao Zhang,Hui Xuan Zhang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.6

A strategy to improve the cross-section homogeneity of thermal oxidative stabilized polyacrylonitrile for carbonmaterials was provided in the present work. A kind of comonomer, dimethyl itaconate (DMI), which possesses two bulkyside groups was introduced into poly(acrylonitrile-co-itaconic acid). The efficiency of DMI in improving the cross-sectionhomogeneity of polyacrylonitrile films during thermal oxidative stabilization (TOS) processes and the properties of resultedPAN-based carbon materials were investigated in detail. It was found that DMI facilitated the formation of longer cyclicstructures, higher oxygen content, more homogeneous cross-section fracture morphology and denser structure during TOSprocess. DMI was also benefit for easing heat release. The presence of DMI also facilitated a smaller ID/IG value of thecarbonized PAN film and a bigger in-plane size of graphite crystals La.