JPNIC IDN-TF Status and Implementations

Hongbo Shi 정보통신정책연구원 2000 세미나및공청회 Vol.2000 No.

Optical Signal Sampling Based on Compressive Sensing with Adjustable Compression Ratio

Hongbo Zhou,Runcheng Li,Hao Chi 한국광학회 2022 Current Optics and Photonics Vol.6 No.3

We propose and experimentally demonstrate a novel photonic compressive sensing (CS) scheme for acquiring sparse radio frequency signals with adjustable compression ratio in this paper. The sparse signal to be measured and a pseudo-random binary sequence are modulated on consecutively connected chirped pulses. The modulated pulses are compressed into short pulses after propagating through a dispersive element. A programmable optical filter based on spatial light modulator is used to realize spectral segmentation and demultiplexing. After spectral segmentation, the compressed pulses are transformed into several sub-pulses and each of them corresponds to a measurement in CS. The major advantage of the proposed scheme lies in its adjustable compression ratio, which enables the system adaptive to the sparse signals with variable sparsity levels and bandwidths. Experimental demonstration and further simulation results are presented to verify the feasibility and potential of the approach.

Experimental Study on Residual Mechanical Properties of Bolt-Sphere Joints After a Fire

Hongbo Liu,Zhilun Tan,Zhihua Chen,Zhansheng Liu,Dongyu Liu 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.3

Through tensile testing of 15 steel bolt-sphere joints and 15 aluminum alloy bolt-sphere joints, infl uencing rules of material type, high temperature and cooling mode on tensile properties of post-fi re bolt-sphere joints were studied, and then failure modes of the joints were determined. According to experimental data, the calculation formula of residual tension capacity of post-fi re bolt-sphere joints was presented. Experimental data indicated that (1) decreased extension on the mechanical properties of aluminum alloy bolt-sphere joints after high temperature in the fi re was signifi cantly higher than that of the steel bolt-sphere joints; (2) when fi re temperature was lower than 800 °C, the tension capacity of steel bolt-sphere joints could be restored by more than 90% after cooling; (3) when fi re temperature was lower than 500 °C, the tension capacity of aluminum alloy bolt-sphere joints could be restored by more than 50% after cooling; (4) bolt-sphere joints could still satisfy the requirement of “strong node and weak member” after a fi re; and (5) material type and fi re temperature were the main factors that infl uenced post-fi re mechanical properties of bolt-sphere joints.

Study on Axial Compression Behavior of Cross-Shaped and L-Shaped Multi-cavity Concrete-Filled Steel Tube Special Shaped Column

Hongbo Li,Yufei Tong,Jianguang Yin,Hubiao Zhang,Changyu Yan 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1

Multi-cavity concrete-fi lled steel tube special shaped column (CFSTSSC) combines the excellent characteristics of multicavity steel tube and core concrete. CFSTSSC has the advantages of high bearing capacity, good ductility, and strong energy dissipation capacity. At present, accurate calculation methods for these kinds of structures are limited and research into crossshaped and L-shaped multi-cavity CFSTSSCs is not available. Therefore, the axial compression behavior of cross-shaped and L-shaped multi-cavity CFSTSSCs has been investigated, though experimental research and numerical simulation, in this study. First, axial compression tests were carried out on three cross-shaped and three L-shaped multi-cavity CFSTSSCs to analyze their failure modes, axial load-strain curve, ductility index, and ultimate bearing capacity. Then, fi nite element (FE) calculation models of cross-shaped and L-shaped multi-cavity CFSTSSCs were established. The FE models are in good agreement with the experimental results, which provides a foundation for further parameter analysis and failure mechanism study of special shaped columns. Finally, combining parameter analysis and limit equilibrium theory, equations for calculating the ultimate bearing capacity of cross-shaped and L-shaped multi-cavity CFSTSSCs were proposed. The results show that the error between the simplifi ed equation and the FE result is less than 15%, indicating that the equations can provide reference for practical engineering applications.

Research on the Influences of Time Harmonics on Permanent Magnet Synchronous Motors with Hybrid Magnet Poles

Hongbo Qiu,Yuedong Guo,Wenfei Yu,Bingxia Tang,Cunxiang Yang 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.3

With the development of electric electron technology and controlling technology, controller for driving permanent magnet synchronous motors is used widely. The using of a controller can expand the motor speed range and improve motor runtime performances. However, the output current of a controller contains lots of time harmonics that will have bad infl uences on motor torque and losses. In order to analyze the infl uences of the time harmonics on the motor performances, diff erent time harmonic currents were injected into the motor armature. Taking a 750 W, 250 r/min permanent magnet synchronous motor with hybrid magnet poles (HPPMSM) as an example, the 2-D fi nite model was established. On this basis, the torque ripple and eddy current losses of permanent magnets with diff erent time harmonics were obtained. The infl uences of time harmonics on motor torque ripple and eddy current losses were determined, and the impacting mechanism was revealed. The analyses may be helpful for the optimal design of HPPMSM.

Reinforcement of Circular Steel Tubes Using Welded Casings Under Axial Compression Loading

Hongbo Liu,Jie Hu,Zhi-Hua Chen,Longxuan Wang,W. A. H. Mashrah 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.3

To explore the mechanical behavior of circular steel tube components strengthened with welded casings, two groups of six specimens are designed, and two working conditions of zero-load reinforcement and load reinforcement are defi ned. Typical failure modes, ultimate bearing capacity, defl ection curves, and strain data of measuring points are obtained. The FE modeling method considering the thermal eff ect of the welding process is proposed and verifi ed. A total of 446 fi nite element models are established to explore the eff ects of the initial defects, the slenderness ratio, the boundary conditions, and the area ratio of the welded casing to the circular steel tube on the ultimate bearing capacity of the strengthened components. In addition, the ultimate bearing capacity equations for zero-load strengthened components is proposed using regression fi tting and considering the adverse eff ects of the residual stresses due to the rolling and welding processes. Moreover, equations for calculating the deformation and the ultimate bearing capacity of the load-strengthened components considering the eff ect of the welding heat are also derived. Finally, the experimental, numerical, and theoretical analyses results were consistent in high calculation validity and effi ciency.

An Interactive Strategy of Grid and Electric Vehicles Based on Master‑Slaves Game Model

Hongbo Cheng,Tong Luo,Chen Kang,Jianbo Xin,Hua Wan,Feng Pei,Xu Tian 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1

In order to avoid the adverse efects of the grid caused by disorder large-scale electric vehicles and improve supporting function of energy storage battery on the power grid, interaction model of electric vehicles (EVs) and the power grid is constructed according to a master-slave game method. Then, the utility functions of each participant are established, and the dynamic constraints of the batteries for EVs are established considering the travel demand of users. Then, based on the YALMIP/CPLEX solver, the optimal response strategy of the EVs can be obtained, and the genetic algorithm is used to solve the Nash equilibrium solution of the master-slaves game model. Moreover, the Monte Carlo method is employed to simulate the user travel data and the basic parameters of EVs in a certain area. Based on these data, the optimal time-of-use price in this area is ofered, and the optimal response strategy of EVs under this price is analyzed. Finally, the study of the case show that the proposed game model can make the strategies of both the EVs and the grid, which can restrict the load fuctuation of the grid and improve the beneft of EVs without afecting their travel.

Correction to: Research on the Infl uences of Time Harmonics on Permanent Magnet Synchronous Motors with Hybrid Magnet Poles

Hongbo Qiu,Yuedong Guo,Wenfei Yu,Bingxia Tang,Cunxiang Yang 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.4

Tensile Properties of Aluminum Alloy Bolt-Sphere Joints under Elevated Temperatures

Hongbo Liu,Ao Gu,Zhi-Hua Chen 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.2

Aluminum alloy bolt-sphere joint is one of the major nodes in aluminum alloy space grid structures. It has been applied in many big projects. In this study, computation methods of mechanical properties and bearing capacity of aluminum alloy bolt-sphere joints in fire are proposed by combining experimental research and theoretical analysis. Results demonstrate that: 1) The tensile strength of aluminum alloy bolt-sphere joints in fire is related to the tensile strength of stainless-steel bolt and the tensile strength seal plate joint. 2) The stainless-steel bolt develops two failure modes, namely, breakage failure of cord and pulling-out failure of screw in fire. 3) The seal plate joint in fire has three tensile failure modes, namely, tensile-shearing combined failure of seal plate at the annular compression position, shear failure of seal plate, and tensile failure of the aluminum alloy tube at the seal plate border. 4) The tensile strength of the stainless-steel bolt begins to decrease significantly when the temperature reaches 300°C. 5) The tensile strength of the seal plate joint begins to decrease sharply when the temperature reaches 200°C. 6) The formula to calculate bearing capacity of aluminum alloy bolt-sphere joints in fire is proposed based on experimental results.

Influence of Inter-turn Short-Circuit Fault Considering Loop Current on Electromagnetic Field of High-Speed Permanent Magnet Generator with Gramme Ring Windings

Hongbo Qiu,Xifang Zhao,Cunxiang Yang,Yi Ran,Yanqi Wei 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.2

As a kind of emergency power supply in military fi eld, the high-speed permanent magnet generator (HSPMG) has attracted wide attention to its healthy condition. The loop current (LC) of the inter-turn short-circuit (ITSC) fault seriously endangers the generator unit operation stability and power supply reliability. In order to study the infl uence of pulsating magnetic fi eld produced by LC on the electromagnetic fi eld, the two-dimensional fi nite element model (FEM) of the 117 kW, 60000 rpm HSPMG is established. By comparing calculation result and test data, the accuracy of the model is verifi ed. The fi eld-circuit coupling method is used to reveal the change mechanism of magnetic fi eld symmetry when ITSC fault occurs. By comparing the spatial distribution of the air-gap fl ux density, the relationship among the spatial distribution of the air-gap fl ux density, the elliptical rotating magneto-motive force (MMF) and the current phase angle is determined. The variation of the amplitude of the air-gap fl ux density space harmonic under diff erent fault degree is studied, and the fault characteristics of ITSC fault are obtained, which provides a reference for ITSC fault diagnosis and fault degree identifi cation. In addition, the research also laid a theoretical foundation for the next analysis of the loss and temperature fi eld.