Thirty-two-tupling frequency millimeter-wave generation based on eight Mach-Zehnder modulators connected in parallel

Xinqiao Chen,Siyuan Dai,Zhihan Li,Wenyao Ba,Xu Chen 한국전자통신연구원 2024 ETRI Journal Vol.46 No.2

A new method is proposed to generate a 32-tupling frequency millimeter wave (MMW) with eight Mach-Zehnder modulators (MZMs) connected in parallel. Theoretical analyses and simulation experiments are conducted. The optical sideband suppression ratio (OSSR) of the obtained ±16th order optical side-bands are 61.54 dB and 61.42 dB, and the radio frequency spurious suppression ratios (RFSSRs) of the generated 32-tupling frequency MMW are 55.52 dB and 55.27 dB based on the theoretical analysis and simulation experiments, respectively; these outcomes verified the feasibility of the new method. The main parameters used to affect the stability of the generated signal are the modulation index and extinction ratio of MZM. Their effects on the OSSR and RFSSR of the generated signals are investigated when they deviate from their designed values. Compared with the other proposed methods for the generation of 32-tupling fre-quency MMW by MZM, our method has the best spectral purity and stability, and it is expected to have important MMW over fiber applications.

Acetylated starch-based biodegradable materials with potential biomedical applications as drug delivery systems

Ling Chen,Xiaoxi Li,Lin Li,Siyuan Guo 한국물리학회 2007 Current Applied Physics Vol.7 No.s1

from tablets coated with starch-based polymer were examined. Maize starch acetates (SA) were prepared by acetyl esterication with adegree of substitution from 1.31 to 2.40, and bovine serum albumin was used as a model drug. Forin-vitrodrug release assays, the starch-based polymer was incubated in simulated gastric uid, simulated intestinal uid and simulated colonic uid, respectively. The resistantstarch content and swelling property of maize starch were increased by acetylation, which retarded its enzymatic degradation. Drugfor a potential drug delivery carrier for colon-targeting biomacromolecule drugs.

Seismic vulnerability of sliding isolation concrete rectangular liquid storage tanks

Xuansheng Cheng,Siyuan Yin,Wenjun Chen,Wei Jing 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.4

Based on the sliding isolation concrete LSS (liquid-storage structure), the specific seismic vulnerability is analyzed according to the general failure mode. In this study, 12 seismic inputs with different characteristics are used, and their acceleration peak values are modulated. By inputting these waves to the sliding isolation concrete storage structure, the finiteelement models of different concrete rectangular LSSs are obtained and analyzed, and the failure probabilities are obtained according to the IDA (incremental dynamic analysis) curves of the structure. The results show that when the seismic acceleration peak value gradually increases from 0.1 g to 1.0 g, the failure probability of LSS gradually increases with the increase in friction coefficient. However, the failure probability of a sliding isolation LSS is less than 100% and far less than the failure probability of a non-isolated rectangular LSS, which shows that an isolated liquid storage structure continues working under a big earthquake. Thus, the sliding isolation for the concrete LSS has a significant damping effect.

Research on diagnosis method of centrifugal pump rotor faults based on IPSO-VMD and RVM

Dong Liang,Chen Zeyu,Hua Runan,Hu Siyuan,Fan Chuanhan,Xiao xingxin 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

Centrifugal pump is a key part of nuclear power plant systems, and its health status is critical to the safety and reliability of nuclear power plants. Therefore, fault diagnosis is required for centrifugal pump. Traditional fault diagnosis methods have difficulty extracting fault features from nonlinear and nonstationary signals, resulting in low diagnostic accuracy. In this paper, a new fault diagnosis method is proposed based on the improved particle swarm optimization (IPSO) algorithm-based variational modal decomposition (VMD) and relevance vector machine (RVM). Firstly, a simulation test bench for rotor faults is built, in which vibration displacement signals of the rotor are also collected by eddy current sensors. Then, the improved particle swarm algorithm is used to optimize the VMD to achieve adaptive decomposition of vibration displacement signals. Meanwhile, a screening criterion based on the minimum Kullback-Leibler (K-L) divergence value is established to extract the primary intrinsic modal function (IMF) component. Eventually, the factors are obtained from the primary IMF component to form a fault feature vector, and fault patterns are recognized using the RVM model. The results show that the extraction of the fault information and fault diagnosis classification have been improved, and the average accuracy could reach 97.87%.

Thermal-hydraulic analysis of He-Xe gas mixture in 2×2 rod bundle wrapped with helical wires

Chenglong Wang,Siyuan Chen,Wenxi Tian,G.H. Su,Suizheng Qiu Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

Gas-cooled space reactor, which adopts He-Xe gas mixture as working fluid, is a better choice for megawatt power generation. In this paper, thermal-hydraulic characteristics of He-Xe gas mixture in 2×2 rod bundle wrapped with helical wires is numerically investigated. The velocity, pressure and temperature distribution of the coolant are obtained and analyzed. The results show that the existence of helical wires forms the vortexes and changes the velocity and temperature distribution. Hot spots are found at the contact corners between helical wires and fuel rods. The highest temperature of the hot spots reach 1600K, while the mainstream temperature is less than 400K. The helical wire structure increases the friction pressure drop by 20%-50%. The effect extent varies with the pitch and the number of helical wires. The helical wire structure leads to the reduction of Nusselt number. Comparing thermal-hydraulic performance ratios (THPR) of different structures, the THPR values are all less than 1. It means that gas-cooled space reactor adopting helical wires could not strengthen the core heat removal performance. This work provides the thermal-hydraulic design basis for He-Xe gas cooled space nuclear reactor.

A Review of Industrial MIMO Decoupling Control

Lu Liu,Siyuan Tian,Dingyu Xue,Tao Zhang,YangQuan Chen,Shuo Zhang 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.5

In recent decades, MIMO (Multi-Input-Multi-Output) systems become more and more widely used inindustrial applications. A variety of decoupling control algorithms have been studied in the literature. Therefore,a review of the most extensively applied coupling interaction analysis and decoupler design methods for industrialprocesses is necessary to be carried out. In this paper, in order to benefit researchers and engineers with differentacademic backgrounds, the scattered coupling interaction analysis and decoupling algorithms are collectedand divided into different categories with their characteristics, application domains and informative comments forselection. Moveover, some frequently concerned problems of decoupling control are also discussed.

The construction of the Ni/La2O2CO3 nanorods catalysts with enhanced low-temperature CO2 methanation activities

Hui Yang,Xueying Wen,Siyuan Yin,Yixin Zhang,Cai-e Wu,Liang Xu,Jian Qiu,Xun Hu,Leilei Xu,Mindong Chen 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.128 No.-

In this work, the La(OH)3 nanorods were successfully synthesized by precisely regulating the parametersof the hydrothermal method. Then, a series of Ni-based CO2 methanation catalysts were fabricated via theincipient-wetness impregnation and deposition–precipitation methods by employing the La(OH)3 nanorodsas the supports. The influences of the support morphology and the preparation method on the metalsupportinteraction, Ni dispersion, and the surface basicity were carefully investigated based on varioustechniques, such as XRD, SEM, H2-TPR, CO2-TPD, XPS, ect. It was found that the rod-shaped La(OH)3 supportedcatalyst prepared by the deposition–precipitation method performed the optimum activity andstability. The reason for this could be derived from the confinement effect of the crystal plane of therod-shaped support, which would promote the formation of the strong metal-support interaction andthe construction of the Ni-La interface with high activity. Furthermore, the online-tandem TG-MS andin-situ DRIFTS technologies were used to investigate the thermal decomposition performance of the catalystprecursors in the calcination process and the reaction intermediates of the CO2 methanation. Therefore, the fundamental roles of support morphology and catalyst preparation method were expectedto direct the advancement of the Ni-based nanostructured catalysts with outstanding low-temperatureperformances.

Multiple Primary Cardiac Malignant Peripheral Nerve Sheath Tumors in the Left Atrium: Case Report

Junfei Li,Qiansu Chen,Shaomei Yu,Siyuan Yang 대한흉부외과학회 2021 Journal of Chest Surgery (J Chest Surg) Vol.54 No.5

Malignant peripheral nerve sheath tumors are rare sarcomas of the heart. Herein, we re- port the case of a 24-year-old man who complained of dyspnea, cough, and upper left back pain. He was found to have multiple primary heart tumors obstructing the right su- perior pulmonary vein in the left atrium, which were diagnosed as malignant peripheral nerve sheath tumors. The patient underwent successful resection of the tumors and im- munohistochemistry was utilized for diagnosis.

Cavitation state identification of centrifugal pump based on CEEMD-DRSN

Dai Cui,Hu Siyuan,Zhang Yuhang,Chen Zeyu,Dong Liang 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.4

Centrifugal pumps are a crucial part of nuclear power plants, and their dependable and safe operation is crucial to the security of the entire facility. Cavitation will cause the centrifugal pump to violently vibration with the large number of vacuoles generated, which not only affect the hydraulic performance of the centrifugal pump but also cause structural damage to the impeller, seriously affecting the operational safety of nuclear power plants. A closed cavitation test bench of a centrifugal pump is constructed, and a method for precisely identifying the cavitation state is proposed based on Complementary Ensemble Empirical Mode Decomposition (CEEMD) and Deep Residual Shrinkage Network (DRSN). First, we compared the cavitation sensitivity of pressure fluctuation, vibration, and liquid-borne noise and decomposed the liquid-borne noise by CEEMD to capture cavitation characteristics. The decomposition results are sent into a 12-layer deep residual shrinkage network (DRSN) for cavitation identification training. The results demonstrate that the liquid-borne noise signal is the most cavitation-sensitive signal, and the accuracy of CEEMD-DRSN to identify cavitation at different stages of centrifugal pumps arrives at 94.61%