Head-mounted display-based intuitive virtual reality training system for the mining industry

Virtual reality(VR) training technology in the mining industry is a new field of research and utilization.The successful application of VR training system is critical to mine safety and production. Through the statistics of the current research and applications of VR training systems in mining industry, all the input/output devices are classified. Based on the classifications of the input/output devices that are used in the VR system, the current VR training systems for the mining industry could be divided into three types: screen-based general type, projector-based customized type, and head-mounted display(HMD)-based intuitive type. By employing a VR headset, a smartphone and a leap motion device, an HMDbased intuitive type VR training system prototype for drilling in underground mines has been developed.Ten trainees tried both the HMD-based intuitive system and the screen-based general control system to compare the experiences and training effects. The results show that the HMD-based system can give a much better user experience and is easy to use. Three of the five components of a VR training system,namely, the user, the tasks, and software and database should be given more attention in future research.With more available technologies of input and output devices, VR engines, and system software, the VR training system will eventually yield much better training results, and will play a more important role in as a training tool for mine safety.

Securing Display Path for Security-Sensitive Applications on Mobile Devices

While smart devices based on ARM processor bring us a lot of convenience,they also become an attractive target of cyber-attacks.The threat is exaggerated as commodity OSes usually have a large code base and suffer from various software vulnerabilities.Nowadays,adversaries prefer to steal sensitive data by leaking the content of display output by a security-sensitive application.A promising solution is to exploit the hardware visualization extensions provided by modern ARM processors to construct a secure display path between the applications and the display device.In this work,we present a scheme named SecDisplay for trusted display service,it protects sensitive data displayed from being stolen or tampered surreptitiously by a compromised OS.The TCB of SecDisplay mainly consists of a tiny hypervisor and a super light-weight rendering painter,and has only^1400 lines of code.We implemented a prototype of SecDisplay and evaluated its performance overhead.The results show that SecDisplay only incurs an average drop of 3.4%.

Decoding the Moon Phase Display Device over the Front Dial of the Antikythera Mechanism

The Antikythera mechanism is the most famous ancient astronomical calculator. The damaged excavation is a critical constraint for decoding the mechanism completely. By the systematic reconstruction design methodology, all feasible designs of the moon phase display device, which is one of the unclear mechanisms of the Antikythera mechanism, are reconstructed. These designs, including ordinary gear trains and epicyclic gear trains, are the simplest designs and satisfy the surviving evidence. The Antikythera mechanism and its reconstruction designs presented by LIN and YAN are introduced first. Three pointer types of the Antikythera mechanism are concluded based on their display motions and the orientation of the mechanism. In accordance with the analysis of the available interior reconstruction designs and the surviving evidence, four feasible designs of the moon phase display device are generated. All of them utilize the ball pointer with black and white that rotates around the radial axis to show cyclic moon phase. Two of these four feasible reconstruction designs are driven by one input source, and their bronze disks are fixed and rotatable respectively. Both of the remaining reconstruction designs are driven by two input sources, and their bronze disks are rotatable. Therefore, the four reconstruction designs of the moon phase display device reveal all possible display conditions of the moon phase pointers and the possible purposes of the bronze disk.

Polarized red, green, and blue light emitting diodes fabricated with identical device configuration using rubbed PEDOT:PSS as alignment layer

Polarized red, green, and blue light emitting diodes(LEDs) are successfully fabricated using polyfluorene and its derivatives, namely, poly(9,9-dioctylfluorene)(PFO), poly(9,9-dioctylfluorene-co-benzothiadiazole)(F8BT),and poly(triphenylamine-co-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole-co-benzo[c]thiadiazole-co-9,9-dioctyl-9 Hfluorene)(Red F).Rubbed hole transport layer poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate)(PEDOT:PSS)is employed in the devices as the alignment layer to achieve fully monodomain alignment in all polymer layers.Red F is blended with F8BT to realize the polarized electroluminescence of red light(dichroic ratio ~3.3), despite having no liquid crystallinity itself.Comparing PFO/F8BT blend to F8BT, higher efficiency of polarized emission is found due to the energy transfer.All the polarized LEDs exhibit pronounced dichroism and efficient polarized emission compared to the non-alignment regular devices.

Organic Thin Film Electroluminescent Passive Matrix Display

Long life green emitting matrix display based on organic light emitting diode is reported. The pixel number is 96×60, equivalent pixel size 0.4×0.4 mm 2, and the pixel gap 0.1 mm. An image with no crosstalk between pixels is obtained. The average luminance of these pixels at duty cycle of 1/64 is 100 cd/m 2, and the power consumption is 0.6 W. The dark room contrast of 1∶100 is achieved without using a polarization filter.

The Colored Oil Property Effect on Switching Behavior of Electro-Fluidic Display

The switchable oil layer driven by electrowetting gives visible color and light valve control, which is the basis of Electro-Fluidic Displays. The colored oil’s property is a key factor that influences the Electro-Fluidic Displays switching behavior. A purple oil was formulated by the oil-soluble purple dye in decane in this study. The dye molecule itself is nonpolar and it doesn’t dissolve in water. The concentration of colored oil influenced the oil/water interfacial tension and oil viscosity. The relationship of EFD switching behavior with oil/water interfacial tension, oil viscosity, and oil conductivity has been systematically investigated. The oil/water interfacial tension decreased with increasing oil concentration, in the meanwhile, the conductivity increased. Oil conductivity was one of the key factors that influenced the Electro-Fluidic Displays optical property. We found for the first time that at the lower oil concentration (2% - 10%), the interfacial tension plays a main role effect on the rupture voltage and response time, but as the conductivity of higher concentration of colored oil increased (at 20%), the rupture voltage-controlled both by conductivity and interfacial tension.

Synthesis and photoluminescence studies of Ba(Gd,Ln)B_9O_(16):Eu^(3+)(Ln=La,Y) phosphors for n-UV LED lighting and display devices

BaGdB9O16：Eu^3＋ and Ba（Gd,Ln）B9O16：Eu^3＋（Ln=La, Y） phosphors were synthesized by solid state diffusion method. The X-ray diffraction, scanning electron microscopy（SEM） and photoluminescence properties were investigated. The as-synthesized BaGdB9O16：Eu^3＋ and Ba（Gd,Ln）B9O16：Eu^3＋（Ln=La, Y） phosphors showed strong red emission under ultraviolet light excitation. By partially substituting Gd^3＋ by La^3＋ and Y^3＋ ions in the host BaGdB9O16：Eu^3＋ materials, the maximum emission intensity was observed for the optimum composition of BaGd0.91La0.8B9O16Eu0.01 phosphor. The experimental results indicated that the Eu doped BaGdB9O16 and Ba（Gd,Ln）B9O16（Ln=La, Y） phosphors were promising red phosphors, which might find potential applications in near-UV excited LED lighting as well as display devices. Comparison of as-synthesized phosphors with standard phosphor used in CFL（compact fluorescent lamp） was also done. Energy transfer mechanism of Gd^3＋ to Eu^3＋ was also discussed in this paper.

Light field head-mounted display with correct focus cue using micro structure array

A new type of light fiehl display is proposed using a head-mounted display （HMD） and a micro structure array （MSA, lens array or pinhole array）. Each rendering point emits abundant rays from different directions into the viewer＇s pupil, and at one time the dense light field is generated inside the exit pupil of the HMD through the eyepiece. Therefore, the proposed method not only solves the problem of accommodation and convergence conflict in a traditional HMD, but also drastically reduces the huge data in real three-dimensional （3D） display. To demonstrate the proposed method, a prototype is developed, which is capable of giving the observer a real perception of depth.

Analysis of optical characteristics of modulation devices with square and circle pixels for 3D holographic display

With the development of the micro/nanolithography, the optic-optic or optic-electronic modulation devices with different pixel shapes and sizes can be used for three-dimensional （3D） dynamical holographic display. The influence of different parameters of the modulation devices on the image quality of the 3D reconstructed object is analyzed for two cases： the phase-only computer-generated holography （CGH） and the complex amplitude CGH. The results quantitatively show that the pixel shape of the modulation devices will affect the quality of the holographic image.

Efficiency balance of a light guide plate with microstructures for a see-through head-mounted display

The efficiency balance phenomenon for see-through head-mounted displays with different microstructure con- ditions can be found both theoretically and using optical simulation software. A simple mathematical calculation is used to determine the relationship between the real image （see-through function） energy and the virtual image energy. The simulation is based on factors taken from previous research studies. It is found that the balance value of the optical efficiency remains almost constant （66.63% to 67.38%） under different microstructure conditions. In addition, suitable conditions for the microstructures in see-through head-mounted displays for daily applications can be predicted.

Temperature-dependent optical response of phase-only nematic liquid crystal on silicon devices

Wavelength-dependent birefringence and dielectric anisotropy.two major optical properties of the nematie liquid crystal materials used in phase-only liquid crystal on silicon（LCOS） devices,are measured as a function of operating temperatures.The dynamic phase modulation depth and threshold voltage of these phase-only LCOS devices are also measured in the corresponding temperature range and compared with theoretical predictions.The results show that the dynamic response time can he reduced significantly by an appropriate increase ol device operative temperature,while the necessary device elements,such as phase modulation depth and threshold voltage,can be maintained at the same time.

Thin Film Encapsulation of Light-Emitting Diodes with Photopolymerized Polyacrylate and Silver Films

A thin film encapsulation of organic light-emitting diodes （OLEDs） is investigated with a multi-layer stack of polyacrylate-Ag-polyacrylate-Ag-polyacrylate-Ag-polyacrylate （PAPAPAP）. It is shown that the fabrication of polyacrylate films by a wet process does not affect the electroluminescent （EL） characteristics of the devices and polyacrylate films together with the silver layers can perform to minimize oxygen and water diffusion into the organic light-emitting device. The structure of polyacrylate（20μm）-Ag（200nm）-polyacrylate（20μm）-Ag（200nm）- polyacrylate（20μm）-Ag（200nm）-polyacrylate（20μm） is demonstrated to enhance dramatically the lifetime of OLEDs.

Design of Learning Media in Mixed Reality for Lao Education

To improve and develop education systems,the communication between instructors and learners in a class during the learning process is of utmost importance.Currently the presentations of 3D models using mixed reality(MR)technology can be used to avoid misinterpretations of oral and 2D model presentations.As an independent concept and MR applications,MR combines the excellent of each virtual reality(VR)and augmented reality(AR).This work aims to present the descriptions of MR systems,which include its devices,applications,and literature reviews and proposes computer vision tracking using the AR Toolkit Tracking Library.The focus of this work will be on creating 3D models and implementing in Unity 3D using the Vuforia SDK platform to develop VR and AR applications for architectural presentations.

Spatially resolved transcriptomics in immersive environments

Spatially resolved transcriptomics is an emerging class of high-throughput technologies that enable biologists to systematically investigate the expression of genes along with spatial information.Upon data acquisition,one major hurdle is the subsequent interpretation and visualization of the datasets acquired.To address this challenge,VR-Cardiomics is presented,which is a novel data visualization system with interactive functionalities designed to help biologists interpret spatially resolved transcriptomic datasets.By implementing the system in two separate immersive environments,fish tank virtual reality(FTVR)and head-mounted display virtual reality(HMD-VR),biologists can interact with the data in novel ways not previously possible,such as visually exploring the gene expression patterns of an organ,and comparing genes based on their 3D expression profiles.Further,a biologist-driven use-case is presented,in which immersive environments facilitate biologists to explore and compare the heart expression profiles of different genes.

Pure RGB Emissions Based on a White OLED Combined with Optical Colour Filters

We report on a white organic light emitting device （OLED） with a single light emitting layer consisting of a greenish-white emitting host bis-（2-（2-hydroxyphenyl） benzothiazole）zinc （Zn（BTZ）2 ） and an orange-red dopant 5,6,11,12-tetraphenylnaphthacene （rubrene）. The Commission Internationale De L＇Eclairage （CIE） coordinates, external quantum efficiency, and brightness of the white OLED are （0.341, 0.334）, 0.63% and 4000 Cd/m^2 at the bias of 20 V, respectively. Pure red-green-blue （RGB） emissions have been successfully achieved from the white OLED combined well with several built-in optical colour filters （CFs）. The CIE coordinates of the white mixture calculated in theory are very close to the coordinates of the white mixture which recorded with spectrophotometer in practice.

Crosstalk reduction in multi-view autostereoscopic three-dimensional display based on lenticular sheet

A method to reduce crosstalk in multi-view autostereoscopic three-dimensional （3D） displays based on the lenticular sheet is proposed. Correcting the luminance values of each parallax image displayed on the display screen is employed. We analyze the causes of crosstalk. We deduce the formulas of crosstalk reduction according to the relationship between crosstalk coefficients of each parallax image observed through the lenticular sheet, luminance values of each parallax image displayed on the display screen, and luminance values of each parallax image observed through the lenticular sheet at each viewing position. Experimental results verify the effectiveness of the proposed method.

Multi-view 3D display with high brightness based on a parallax barrier

A multi-view three-dimensional （3D） display provides a more realistic experience than a two-view 3D dis- play. Therefore, a multi-view 3D display with high brightness based on a parallax barrier is proposed. The parallax barrier in the 3D display has a gradient transmittance with enhanced frequency character- istic, which indicates that the aperture ratio of the parallax barrier can be increased, thereby improving brightness. Gradient transmittance is also helpful in reducing crosstalk. A prototype of the 3D display is developed. Experimental result shows that the 3D display has higher brightness than a conventional display. In addition, crosstalk is limited at a low level.

A robust photometric calibration framework for projector-camera display system

A novel photometric calibration framework is presented for a projector-camera （ProCam） display system, which is currently under booming development. Firstly, a piecewise bilinear model and five 5-ary color coding images are used to construct the homography between the image planes of a projector and a camera. Secondly, a photometric model is proposed to describe the data flow of the ProCam display system for displaying color images on colored surface in a general way. An efficient self-calibration algorithm is correspondingly put forward to recover the model parameters. Aiming to adapt this algorithm to different types of ProCam display system robustly, a 3× 7 masking coupling matrix and a patches image with 1024 color samples are adopted to fit the complex channel interference function of the display system. Finally, the experimental results demonstrate the validity and superiority of this calibration algorithm for the ProCam display system.

Speckle analysis in laser scanning display system

The theory of speckle formation in laser scanning display system is established based on the averaging effect of eye response as laser beam scanning through an eye resolution spot. It is analyzed that speckle reduction can be obtained by averaging states of speckle during scanning. The theoretical results show that a smaller correlation length of screen surface and the narrowing of laser beam in scanning direction can reduce speckle contrast for this system.

平视显示器的设计

平视显示器作为航空飞行器的主显仪表 ,较好地解决了飞行员不能同时观察飞行参数和外界环境的矛盾 .本文论述了平视显示器的设计思想 。