New Eu³⁺-activated bismuthate tellurate LiSrBiTeO₆ red-emitting phosphor for InGaN-based w-LEDs

He, Jianyue,Gao, Zhiwen,Liu, Shihua,Jeong, Jung Hyun,Yu, Ruijin,Deng, Bin Elsevier 2018 Journal of luminescence Vol.202 No.-

<P><B>Abstract</B></P> <P>A series of novel Eu<SUP>3+</SUP>-doped LiSrBiTeO<SUB>6</SUB> red-emitting phosphors were prepared by the solid-state reaction method for the first time. Its crystal structure and luminescence properties are investigated. X-ray powder diffraction patterns in combination with the Rietveld method reveal its single phase structure. The phosphor can be efficiently excited by 394 nm and 465 nm light and emits bright red luminescence at 616 nm corresponding to the electric dipole transition <SUP>5</SUP>D<SUB>0</SUB>–<SUP>7</SUP>F<SUB>2</SUB>. The optimal doping concentration of LiSrBi<SUB>1-<I>x</I> </SUB>TeO<SUB>6</SUB>:<I>x</I>Eu<SUP>3+</SUP> is about 40 mol%. The thermal stability of the phosphor was tested by measuring their temperature-dependent emission intensities. The warm white light LEDs was fabricated based on the InGaN-chip. The chromaticity coordinates of fabricated w-LED are (0.344, 0.381). All results indicated that LiSrBiTeO<SUB>6</SUB>:Eu<SUP>3+</SUP> phosphors have potential application as red phosphors in white light emitting diodes.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Wheel-Rail Stick-Slip Characteristics under Coupling Damages of Rail Corrugation and Wheel Flat in Metro

Zhiqiang Wang,Jianyue Zhu 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.4

To investigate wheel-rail contact stick-slip characteristics (SSCs) under coupling damages of rail corrugation and wheel flat and explain the co-action mechanism of the two damages, a vehicle-track system model was built, and the SSCs were analyzed by employing the index of the overall dispersion rate of adhesion coefficient (ODRAC). The results show that both inner and outer wheel-rail systems (WRSs) on the curve have a propensity for stick-slip motion. Since the values of SSCs of the inner WRS are 1.204 to 2.963 times higher than those of the outer one, the inner WRS is easier to stick-slip vibration (SSV). When the rail corrugation is fixed, the overall dispersion rates of adhesion coefficients (ODRACs) progressively decrease with the increase of flat depth and length, and the decrease range is 2.766 − 41.775%. When the wheel flat is fixed, the ODRACs also progressively decrease as the corrugation wavelength increases, and the decrease ranges from 7.129% to 42.474%; the ODRACs incrementally increase together with the increase of the corrugation wave depth, and the increase ranges from 10.030% to 30.380%. The presence of flat will attenuate the level of SSV of the original system with rail corrugation, whilst the presence of corrugation will intensify the level of SSV of the original system with wheel flat.

Preparation and study on the spectral properties of garnet-type Li₃Gd₃Te₂O₁₂:Dy³⁺ single-phase full-color phosphor

Liu, Shihua,He, Jianyue,Wu, Zhaoyi,Jeong, Jung Hyun,Deng, Bin,Yu, Ruijin Elsevier 2018 Journal of luminescence Vol.200 No.-

<P><B>Abstract</B></P> <P>Novel single-phased white-light-emitting Li<SUB>3</SUB>Gd<SUB>3</SUB>Te<SUB>2</SUB>O<SUB>12</SUB>:<I>x</I>Dy<SUP>3+</SUP> (<I>x</I> = 0.005, 0.01, 0.02, 0.05, 0.08, 0.10, and 0.15) garnet-type tellurate phosphors were firstly synthesized. The X-ray powder diffraction analysis, photoluminescence excitation and emission spectra, thermal quenching, and decay curves were applied to investigate the phase structure, luminescence, and thermal stability properties. Under the excitation of 351 nm, the emission of Li<SUB>3</SUB>Gd<SUB>3</SUB>Te<SUB>2</SUB>O<SUB>12</SUB>:0.02Dy<SUP>3+</SUP> sample centered at blue (488 nm) and yellow (580 nm), corresponding to <SUP>4</SUP>F<SUB>9/2</SUB>–<SUP>6</SUP>H<SUB>15/2</SUB> transition and <SUP>4</SUP>F<SUB>9/2</SUB>–<SUP>6</SUP>H<SUB>13/2</SUB> transition, respectively. The optimum dopant concentration of Dy<SUP>3+</SUP> ions in Li<SUB>3</SUB>Gd<SUB>3</SUB>Te<SUB>2</SUB>O<SUB>12</SUB>:<I>x</I>Dy<SUP>3+</SUP> was around 2 mol%. The thermal-quenching temperature was above 500 K for Li<SUB>3</SUB>Gd<SUB>3</SUB>Te<SUB>2</SUB>O<SUB>12</SUB>:0.02Dy<SUP>3+</SUP>. The tunable white light and correlated color temperature can be achieved in the present Li<SUB>3</SUB>Gd<SUB>3</SUB>Te<SUB>2</SUB>O<SUB>12</SUB>:<I>x</I>Dy<SUP>3+</SUP> phosphors by adjusting the yellow to blue intensity ratio based on the concentration of Dy<SUP>3+</SUP> ions. The fabricated warm white LED indicates the phosphor could be a single-component white light-emitting phosphor for UV light-emitting diodes.</P>

Suppression of abnormal chattering of a high-speed EMU carbody

Dao Gong,Zegen Wang,Jinsong Zhou,Jianyue Zhu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4

A carbody chattering phenomenon accompanied by bogie hunting movement was investigated. The online test results showed that the vehicle at a large tread conicity state exhibited insufficient stability when running at higher speeds, causing the hunting frequency of the bogie to continuously increase, approach the diamond-shaped deformation modal frequency of the carbody, consequently causing the carbody to chatter. To improve the running stability of the vehicle, to suppress the carbody chattering, a two-step progressive optimisation method that combined analytical optimisation, simulation optimisation to optimise the parameters of the anti-yaw damper was proposed. Furthermore, the effect of optimisation was experimentally verified. Results showed that after optimisation, the critical speed of the vehicle under the condition of worn wheel was significantly enlarged, the bogie exhibited no obvious hunting motion, carbody chatter was significantly alleviated, both the ride quality, the curve passing performance were improved.

Interfacial Reaction in (Mg-37.5Al)/(Mg-6.7Nd) Diffusion Couples

Jiahong Dai,Shijun Shen,Bin Jiang,Jianyue Zhang,Qingshan Yang,Zhongtao Jiang,Hanwu Dong,Fusheng Pan 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.1

The solid-state diffusion reaction between Mg-37.5Al and Mg-6.7Nd was studied in the 623-673 K temperature range. A solid-liquid contact method was employed to produce diffusion couples. The Al4Nd, Al11Nd3, Al3Nd and Al2Nd intermetallic compounds form in the diffusion reaction layers of the couples. The formation of intermetallic compounds in the diffusion reaction layers is rationalized using the Miedema model. The local average compositions through the diffusion reaction layer were determined, and used to construct a semi-quantitative diffusion path on the isothermal Mg-Al-Nd ternary phase diagram at 673 K. The growth constants of the entire diffusion reaction layers were determined as 8.91 (±0.94)×10 -14 m 2 /s, 1.39 (±0.15)×10 -13 m 2 /s and 1.93 (±0.38)×10 -13 m 2 /s at 623 K, 648 K and 673 K, respectively. The activation energy Q for the growth of the entire diffusion reaction layers was 54±4.6 kJ/mol.

Integrated Modeling for the Design of Deformable Mirrors Using a Parametric Module Method

Junqing Zhu,Wei Sha,Changzheng Chen,Xingxiang Zhang,Jianyue Ren 한국광학회 2015 Current Optics and Photonics Vol.19 No.5

Active optics is a key technology for future large-aperture space telescopes. In the design of deformablemirrors for space applications, the design parameter trade-off between the number of regularly configuredactuators and the correction capability is essential but rarely analyzed, due to the lack of design legacy. This paper presents a parametric module method for integrated modeling of deformable mirrors withregularly configured actuators. A full design parameter space is explored to evaluate the correctioncapability and the mass of deformable mirrors, using an autoconstructed finite-element parametric modelingmethod that utilizes manual finite-element meshing for complex structures. These results are used to providedesign guidelines for deformable mirrors. The integrated modeling method presented here can be used forfuture applied optics projects

Integrated Optimization Design of Carbon Fiber Composite Framework for Small Lightweight Space Camera

Shuai Yang,Wei Sha,Changzheng Chen,Xingxiang Zhang,Jianyue Ren 한국광학회 2016 Current Optics and Photonics Vol.20 No.3

A Carbon Fiber Composite (CFC) framework was designed for a small lightweight space camera. According to the distribution characteristics of each optical element in the optical system, CFC (M40J)was chosen to accomplish the design of the framework. TC4 embedded parts were used to solve the lowaccuracy of the CFC framework interface problem. An integrated optimization method and the optimizationstrategy which combined a genetic global optimization algorithm with a downhill simplex local optimizationalgorithm were adopted to optimize the structure parameters of the framework. After optimization, thetotal weight of the CFC framework and the TC4 embedded parts is 15.6 kg, accounting for only 18.4%that of the camera. The first order frequency of the camera reaches 104.8 Hz. Finally, a mechanicalenvironment test was performed, and the result demonstrates that the first order frequency of the camerais 102 Hz, which is consistent with the simulation result. It further verifies the rationality and correctnessof the optimization result. The integrated optimization method mentioned in this paper can be applied tothe structure design of other space cameras, which can greatly improve the structure design efficiency.

A Coaxial and Off-axial Integrated Three-mirror Optical System with High Resolution and Large Field of View

Zhe Chen,Junqing Zhu,Jiantao Peng,Xingxiang Zhang,Jianyue Ren 한국광학회 2016 Current Optics and Photonics Vol.20 No.1

A novel optical design for high resolution, large field of view (FOV) and multispectral remote sensingis presented. An f/7.3 Korsch and two f/17.9 Cook three-mirror optical systems are integrated by sharingthe primary and secondary mirrors, bias of the FOV, decentering of the apertures and reasonable structurearrangement. The aperture stop of the Korsch system is located on the primary mirror, while those ofthe Cook systems are on the exit pupils. High resolution image with spectral coverage from visible tonear-infrared (NIR) can be acquired through the Korsch system with a focal length of 14 m, whilewide-field imaging is accomplished by the two Cook systems whose focal lengths are both 13.24 m. The full FOV is 4°×0.13°, a coverage width of 34.9 km at the altitude of 500 km can then be acquiredby push-broom imaging. To facilitate controlling the stray light, the intermediate images and the real exitpupils are spatially available. After optimization, a near diffraction-limited performance and a compactoptical package are achieved. The sharing of the on-axis primary and secondary mirrors reduces the costof fabrication, test, and manufacture effectively. Besides, the two tertiary mirrors of the Cook systemspossess the same parameters, further cutting down the cost.

Design and Characteristic Measurement of 8000 mm Large Aperture Integrating Sphere

Zhao Zhang,Zhi Wan,Xiansheng Li,Hongxing Liu,Jingxu Sun,Zexun Liu,Yamin Wang,Jianwei Ren,Jianyue Ren 한국광학회 2016 Current Optics and Photonics Vol.20 No.4

Integrating spheres play a central role in the radiometric calibration of remote sensors. With thedevelopment of the wide field of view (FOV) remote sensors, aperture diameters of remote sensors arebecoming larger and larger. To satisfy the radiometric calibration requirements of full FOV and fullaperture, an 8000mm diameter large aperture integrating sphere uniform source with a variable exit portwas designed and manufactured. This integrating sphere will be used for pre-launch test and radiometriccalibration of remote satellites. In this paper, optical theories were used to design the output spectralradiance. The LightTools software based on ray-tracing simulation method was used to determine the bestcombination and distribution of inner light sources. A spectral experiment was made to verify the spectralradiance design. To reduce the influence of longtime power-on, a new characteristic measurement methodwas developed to obtain the radiation characteristic of the integrating sphere, which could greatly improvethe measuring efficiency. This method could also be applied to measure other large aperture uniformsources. The obtained results indicate that the spatial uniformity is 98.35%, and the angular uniformityat center position is 98.78%.

Visualization Method of 3-D Data Field in the Higher Performance Volumetric-Swept Display System

Jian Yue,Chunlin Shen,Yuhui Zheng,Jin Wang 보안공학연구지원센터(IJUNESST) 2013 International Journal of u- and e- Service, Scienc Vol.6 No.1