An ultra-thin dual-band wide-angle polarization-insensitive metamaterial absorber with near-unity absorbance

Shijun Ji,Chengxin Jiang,Ji Zhao,Jilong Yang,Jili Wang,Handa Dai 한국물리학회 2019 Current Applied Physics Vol.19 No.11

In this paper, a dual-band metamaterial absorber (MMA) with wide-angle and polarization-insensitivity is proposed. The MMA consists of two copper layers with a layer of FR-4 between them. And its top layer consists of a cross-shaped resonator and a square ring resonator. The calculation result demonstrates that there are two distinct absorption peaks, whose absorptivity are 99.933% at 3.8441 GHz and 99.99% at 9.1094 GHz. And its thickness is only 1.34% of the wavelength of the lowest absorption frequency. The dual-band MMA shows polarization-insensitivity for normal incident wave and shows high absorptivity in a wide incident angle for both TE and TM polarization wave. In addition, we discuss the working mechanism. The influences of main parameters on the dual-band MMA's absorption are also analyzed. The proposed ultra-thin MMA has simple structure and high absorptivity, which has many potential applications, such as thermal radiometer, detection sensor, stealth technology.

Ultra-precision machining of a large amplitude umbrella surface based on slow tool servo

Peixing Ning,Ji Zhao,Shijun Ji,Jingjin Li,Handa Dai 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.11

Due to its excellent optical performance and system integration property, micro-nano structure function surface has been widely used in optical apparatus and energy collection equipment. But using traditional processing method can’t obtain a mirror-like surface with high form accuracy and low roughness for sake of its complex micro-nano structure. In this paper, a large amplitude umbrella surface is special designed and single point diamond turning (SPDT) technology based on slow tool servo (STS) is used for umbrella surface machining. The tool path generation, tool radius compensation and tool geometry optimization are detailed for fabricating the desired surface. A new method combined with constant angle and analytical mathematical optimization is proposed for tool path optimization. A large amplitude umbrella surface with the maximum amplitude 0.2 mm and period 8 per cycle is designed, and the machining experiment is carried out on Nanoform 250 ultra-precision machine tool. From the form accuracy 1 μm in surface residual error and 279.12 nm in RMS and the surface roughness 230.10 nm in Ra for the machined surface, it can be seen that a large amplitude umbrella surface is easily fabricated by SPDT under STS controlling.

An Innovative Training Program on Engineering Education

Juncai Sun,Song Li,Shijun Ji 한국공학교육학회 2014 공학교육연구 Vol.17 No.4

From 2010, an “excellent engineer” undergraduate and graduate program had been initiated in higher education of China to promote thedevelopment of industry and social economy. In this circumstance, the engineering education programs in Dalian Maritime Universityare reformed to satisfy the requirements of transportation industries. And the engineering practice, engineering activities, and engineeringcourses are emphasized. In this training program, industrial communities are deeply involved in the engineering education and trainingprocedure; the students are educated and trained in university and enterprise according to the common standards and industrial standards;and the engineering competences and creative ability are emphasized and are to be enhanced in the training schedules and procedure. A joint-training mode has been established already between Dalian Maritime University and enterprises in transportation fields.

An Innovative Training Program on Engineering Education

Sun, Juncai,Li, Song,Ji, Shijun Korean Society for Engineering Education 2014 공학교육연구 Vol.17 No.4

From 2010, an "excellent engineer" undergraduate and graduate program had been initiated in higher education of China to promote the development of industry and social economy. In this circumstance, the engineering education programs in Dalian Maritime University are reformed to satisfy the requirements of transportation industries. And the engineering practice, engineering activities, and engineering courses are emphasized. In this training program, industrial communities are deeply involved in the engineering education and training procedure; the students are educated and trained in university and enterprise according to the common standards and industrial standards; and the engineering competences and creative ability are emphasized and are to be enhanced in the training schedules and procedure. A joint-training mode has been established already between Dalian Maritime University and enterprises in transportation fields.

Cathode Materials LaNi1−xCuxO3 for Low Temperature Solid Oxide Fuel Cells

Juncai Sun,Chengli Wang,Song Li,Shijun Ji 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.12

New cathode materials LaNi1−xCuxO3 (typically LaNi0.8Cu0.2O3) were synthesized using a co-precipitation method. The structure and morphology of the powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite material [Ce0.8Sm0.2O2-ä(SDC) and carbonate (Na2CO3,Li2CO3)], NiO and LaNi1−xCuxO3 were used as the electrolyte, anode and cathode, respectively. The electrochemical performance of La-Ni-Cu-O perovskite oxide at low temperatures (400~550oC) was studied. The results showed that LaNi0.8Cu0.2O3 precursor powder prepared through a co-precipitation method and calcined at 860oC for 2 h formed uniform grains with diameters in the range of 400~500 nm. The maximum power density and the short circuit current density of the single cell unit at 550oC were found to be 390 mW/cm2 and 968 mA/cm2, respectively. New cathode materials LaNi1−xCuxO3 (typically LaNi0.8Cu0.2O3) were synthesized using a co-precipitation method. The structure and morphology of the powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite material [Ce0.8Sm0.2O2-ä(SDC) and carbonate (Na2CO3,Li2CO3)], NiO and LaNi1−xCuxO3 were used as the electrolyte, anode and cathode, respectively. The electrochemical performance of La-Ni-Cu-O perovskite oxide at low temperatures (400~550oC) was studied. The results showed that LaNi0.8Cu0.2O3 precursor powder prepared through a co-precipitation method and calcined at 860oC for 2 h formed uniform grains with diameters in the range of 400~500 nm. The maximum power density and the short circuit current density of the single cell unit at 550oC were found to be 390 mW/cm2 and 968 mA/cm2, respectively.

Cathode Materials LaNi_1−xCu_xO₃ for Low Temperature Solid Oxide Fuel Cells

Sun, Juncai,Wang, Chengli,Li, Song,Ji, Shijun The Korean Ceramic Society 2008 한국세라믹학회지 Vol.45 No.12

New cathode materials $LaNi_{1-x}{Cu_x}{O_3}$ (typically $LaNi_{0.8}Cu_{0.2}O_3$) were synthesized using a co-precipitation method. The structure and morphology of the powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite material [$Ce_{0.8}Sm_{0.2}O_{2-\ddot{a}}$(SDC) and carbonate (${Na_2}{CO_3},{Li_2}{CO_3}$)], NiO and $LaNi_{1-x}{Cu_x}{O_3}$ were used as the electrolyte, anode and cathode, respectively. The electrochemical performance of La-Ni-Cu-O perovskite oxide at low temperatures ($400{\sim}550^{\circ}C$) was studied. The results showed that $LaNi_{0.8}Cu_{0.2}O_3$ precursor powder prepared through a co-precipitation method and calcined at $860^{\circ}C$ for 2 h formed uniform grains with diameters in the range of $400{\sim}500\;nm$. The maximum power density and the short circuit current density of the single cell unit at $550^{\circ}C$ were found to be $390\;mW/cm^2$ and $968\;mA/cm^2$, respectively.