Virtual reality research and development in NTU

In 1981,Nanyang Technological Institute was established in Singapore to train engineers and accountants to keep up with the fast-growing economy of the country.In 1991,the institute was upgraded to Nanyang Technological University(NTU).NTU holds the rank for world's top young university for six consecutive years according to the Quacquarelli Symonds(QS)world university ranking.Virtual Reality(VR)research began in NTU in the late 1990s.NTU's colleges,schools,institutes,and centers have contributed toward the excellence of VR research.This article briefly describes the VR research directions and activities in NTU.

Intelligent virtualization of crane lifting using laser scanning technology

Background This paper presents an intelligent path planner for lifting tasks by tower cranes in highly complex environments,such as old industrial plants that were built many decades ago and sites used as tentative storage spaces.Generally,these environments do not have workable digital models and 3 D representations are impractical.Methods The current investigation introduces the use of cutting edge laser scanning technology to convert real environments into virtualized versions of the construction sites or plants in the form of point clouds.The challenge is in dealing with the large point cloud datasets from the multiple scans needed to produce a complete virtualized model.The tower crane is also virtualized for the purpose of path planning.A parallelized genetic algorithm is employed to achieve intelligent path planning for the lifting task performed by tower cranes in complicated environments taking advantage of graphics processing unit technology,which has high computing performance yet low cost.Results Optimal lifting paths are generate d in several seconds.

Preparation and photocatalytic performance study of dual Z-scheme Bi_(2)Zr_(2)O_(7)/g-C_(3)N4/Ag_(3)PO_(4) for removal of antibiotics by visible-light

At present,the high re-combination rate of photogenerated carriers and the low redox capability of the photocatalyst are two factors that severely limit the improvement of photocatalytic performance.Herein,a dual Z-scheme photocatalyst bismuthzirconate/graphitic carbon nitride/silver phosphate (Bi_(2)Zr_(2)O_(7)/g-C_(3)N4/Ag_(3)PO_(4)(BCA)) was synthesized using a co-precipitation method,and a dual Z-scheme heterojunction photocatalytic system was established to decrease the high re-combination rate of photogenerated carriers and consequently improve the photocatalytic performance.The re-combination of electron-hole pairs(e-and h+) in the valence band (VB) of g-C_(3)N4increases the redox potential of e-and h+,leading to significant improvements in the redox capability of the photocatalyst and the efficiency of e--h+separation.As a photosensitizer,Ag_(3)PO_(4)can enhance the visible light absorption capacity of the photocatalyst.The prepared photocatalyst showed strong stability,which was attributed to the efficient suppression of photo-corrosion of Ag_(3)PO_(4)by transferring the e-to the VB of g-C_(3)N4.Tetracycline was degraded efficiently by BCA-10%(the BCA with 10 wt.%of AgPO_(4)) under visible light,and the degradation efficiency was up to 86.2%.This study experimentally suggested that the BCA photocatalyst has broad application prospects in removing antibiotic pollution.

Energy transfer and 2 μm emission in Tm^(3+)/Ho^(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders

（Y0.87La0.1Zr0.03）2O3 nanopowders doped with various concentrations of Tm^3＋ and Ho^3＋ were prepared by the citrate method. The standard cubic Y2O3 phase can be matched in the Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2 O3 nanopowders. The nanopowders exhibit average particle sizes of 40,60, 80 and 100 nm after calcinated at 900,1000,1100 and 1200℃,respectively. The energy transfer from Tm^3＋ to Ho^3＋ and the optimum fluorescence emission around 2 μm were investigated. Results indicate that the emission bands at around 1.86 and 1.95 μm correspond to 3 F4→3 H6 transition of Tm^3＋ and 5 I7→5 I8 transition of Ho^3＋, respectively.Better spectral properties were achieved in Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2O3 nanopowders with the average size of 100 nm obtained at the conditions of the treatment of precursors calcinated at 1200 ℃ for 2 h doped with 1.5 mol% Tm^3＋ and 1 mol% Ho^3＋.

Reversible enhanced upconversion luminescence by thermal and electric fields in lanthanide ions doped ferroelectric nanocomposites

Luminescence modification of lanthanide ions has attracted great attention due to its applications in sensing,colorful display, information transmission and anti-counterfeiting. Traditional methods of tuning fluorescence typically employ tuning compositions that are not conducive to the development of multi-environment detection and anti-counterfeiting. In this study, lanthanide ions doped ferroelectric nanocomposite was exploited with external stimuli. The upconversion luminescence modification was preformed via both the thermal and electric fields. The anti-thermal quenching phenomenon was observed in the prepared nanocomposite, which could effectively enhance the upconversion luminescence of lanthanide ions. Based on the electromechanical softness of the ferroelectric lattice, exceptional luminescence modification was realized through electric polarization. The luminescence modifications by thermal and electric fields exhibited excellent reversibility and non-volatility. These results provide unique insights into the development of integrated stimulus responsive smart devices, colorful display and advanced multi-mode sensing materials.

Sintering Behavior and Microwave Dielectric Properties of MgTiO_3 Ceramics Doped with B_2O_3 by Sol-Gel Method

The B2O3-doped MgTiO3 powders and ceramics have been prepared by sol-gel method using Mg（NO3）2-6H2O, Ti（C4H9O）4 and H3BO3 as the starting materials. The sintering behavior and microwave dielectric properties of ceramics prepared from powders with different particle sizes were investigated. The gels were calcined at 650, 700, 750, 800, 850 and 900 ℃ and the derived particle sizes of powders were 20-30 nm, 30-40 nm, 40-60 nm, 60-90 nm, 90-120 nm and 120-150 nm, respectively. The nanoparticles with the size of 30-60 nm benefited the sintering process with high surface energy whereas nanoparticles with the size of 20-30 nm damaged the microwave dielectric properties due to the pores in the ceramics. The addition of B203 used as a liquid sintering aid reduced the sintering temperature of MgTiO3 ceramic, which was supposed to enter the MgTi03 lattice and resulted in the formation of （MgTi）2（BO3）O phase. The B203-doped MgTiO3 ceramic sintered at 1100℃ and prepared from the nanoparticles of 40-60 nm had compact structure and exhibited good microwave dielectric properties： εr=17.63, Q x f=33,768 GHz and Tf=-48X 10-6 ℃-1.