Wide-angle View Research Articles

A wide angle view of the Sagittarius dwarf spheroidal galaxy

We report on the discovery and chemical abundance analysis of the first CEMP-r/s star detected in the Sagittarius dwarf spheroidal galaxy (Sgr dSph) by means of UVES high-resolution spectra. The star, found in the outskirts of Sgr dSph, along the major axis of the main body, is a moderately metal-poor giant (Teff = 4753 K, log g = 1.75, [Fe/H] = −1.55) with [C/Fe] = 1.13, placing it in the so-called “high-carbon band”, and strong s-process and r-process enrichment ([Ba/Fe] = 1.4, [Eu/Fe] = 1.01). Abundances of 29 elements from C to Dy were obtained. The chemical pattern appears to be best fitted by a scenario where an r-process pollution event pre-enriched the material out of which the star was born as secondary in a binary system whose primary evolved through the AGB phase, providing C- and s-process enrichment.

Generation of a polarized optical field from a given scalar field for wide-viewing-angle holographic displays

Although the scalar wave theory does not fully describe the nature of the light, which is a vector wave field, it is common to characterize the optical field propagated from an object as a scalar wave in 3DTV research. A given scalar wave field is usually directly mapped to the transverse field components of a simply polarized optical field during the generation of the optical field by a holographic 3D display; this procedure gives accurate results in terms of the optical intensity if the field is paraxial. However, due to the nonnegligibly large longitudinal component of the vector field, this method fails in wide-angle fields. In order to generate a polarized optical field which has the same resultant effect as prescribed by a wide-angle scalar field, we extend this simple polarization approach to tilted and rotated planes. That is, we first put a constraint on the generated vector wave field such that each plane wave component has a simple polarization relation at its locally transverse plane. Then, we map the complex plane wave amplitudes of a given scalar field to the plane wave amplitudes of locally transverse field components of the polarization-constrained optical field. As a consequence of the developed mapping, for an observer which is located at a tilted and rotated plane and captures a locally paraxial segment of the incoming wave field, the intended scalar intensity results can also be obtained in wide-viewing-angle 3D holographic displays. The developed model is valid if the chosen local coordinate frames of the locally transverse planes of the propagating plane waves vary slowly as the propagation direction changes. For a 3DTV setup where the display is located at a z-plane and the observers are located away from the z-axis, an analytical representation for appropriate coordinate frames is developed. For the same setup, computer simulation results showed that the excessive amplification of the longitudinal component due to the conventional mapping does not arise in the proposed method and the desired scalar results are observed. Moreover, since the determined polarization state is preserved at each tilted and rotated plane, the new model can also be used in an optical setup where the polarization information is important. As a result, the proposed mapping enables the scalar wave theory to be used in wide-viewing angle holographic display applications under the given constraints.

Comparison of Scleral Buckling and Vitrectomy Using Wide Angle Viewing System for Rhegmatogenous Retinal Detachment

ABSTRACT Purpose: To compare the surgical results of pars plana vitrectomy (PPV) and scleral buckling (SB) using the same vitreoretinal viewing system for rhegmatogenous retinal detachment (RRD) Methods: The study was a retrospective analysis of the medical records of 52 eyes (52 patients) with uncomplicated RRD located in superior quadrants. Eyes with pseudophakia or complications were not included. Thirty-one eyes underwent PPV using a wide-angle viewing system (WAVS) and 21 eyes received SB using the same WAVS combined with a chandelier endoilluminator. The primary anatomical success rate was the main outcome, defined as the proportion of eyes with successful reattachment of the retina. Results: The primary anatomical success rate was 90.5% in the SB group and 90.3% in the PPV group. Both groups achieved 100% of the final success rate. Although no significant difference was observed between the two groups, temporary intraocular pressure elevation and post-operative cataract formation were more frequent in the PPV group. In patients under the age of 55, post-operative cataract formation was significantly less common in the SB group. (P = .045) Conclusions: Under the same vitreoretinal visualization techniques, both SB and PPV had similar anatomical success rates. Chandelier‑assistance WAVS may increase the popularity of SB to treat primary RRD, allowing many patients to receive the benefits of SB surgery.

Large-size updatable optically addressed spatial light modulator (OASLM) based on ZnO nanoparticles for large-area holographic 3D displays

Optically addressed spatial light modulators (OASLMs) provide an appropriate solution for large-area and wide-viewing angle holographic displays because of the possibility of uploading holograms on it through tiling and with sub-micron diffraction feature sizes. A prototype with a large-size OASLM of 100 mm × 100 mm was fabricated using a solution-based deposition process for ZnO nanoparticles (NPs). ZnO NP-based OASLM is suitable for hologram tiling because of the extended charge carrier lifetime as a result of trap states in the ZnO NP layer annealed at a low temperature of 180°C, of which the activation energy was determined firstly by low-temperature measurements. Operating the ZnO NP OASLM in a DC driving mode was subsequently proposed, to utilize the extended charge carrier lifetime in the photosensor layer for temporary information storage. Finally, techniques to tile computer generated holograms (CGHs) spatially on a single OASLM were explored and evaluated, including the demonstration of simultaneous image replay from sequentially tiled two separate phase-only CGHs.

2019 Wallace Foundation Distinguished Lecture Education Research and the Disruption of Racialized Distortions: Establishing a Wide Angle View

Given contemporary recognition of how racialized micro-interactions and the embedded distortions of marginalized and minoritized folk compound over time to produce and reify educational stratification and inequality, this article is an opportunity to think more deliberately about how education researchers can better delineate empirically and conceptually the complexity and temporal spread of these micro-moments, their reproductive momentum, and the prospects for disruption. In capturing these more complex dynamics, scholars are better positioned to generate more nuanced and precise representations of racially minoritized folk and, by implication, White folk. These research commitments require the utilization of the analytical stance I refer to as the wide angle view. This article outlines the parameters and affordances of this view and the interpretive and methodological practices that follow.

Cyber-enhanced canine suit with wide-view angle for three-dimensional LiDAR SLAM for indoor environments

Understanding the topographical information of the disaster site can enhance the efficiency and safety of search and rescue missions. This study describes the development of a cyber-enhanced canine suit for three-dimensional (3D) simultaneous localization and mapping within indoor environments. The suit’s weight was approximately 3.0 kg and was compatible with large dogs (>30.0 kg). It could collect dense, wide view-angle, and long-range 3D point clouds. The collected point clouds were processed offline to create 3D maps. The suit was equipped with a protective cover that could prevent physical damage to the light imaging detection and ranging (LiDAR) sensor from collision. The protective cover was designed to (a) eliminate any effects on the performance of the 3D LiDAR and (b) sustain the stress from the impact at the velocity of 20.0 m/s with no physical damage. Additionally, the canine suit was also modified for better fitting and stability of the LiDAR on a wider range of dog bodies. The performance of the suit was demonstrated on real dogs in four different scenarios in areas with different space sizes, dog gait patterns, and ground layouts. The space size and position errors observed did not exceed 0.80% and 1.13%, respectively.

Planar microwave retroreflector based on transmissive gradient index metasurface

In this paper, a novel planar microwave retroreflector based on a transmissive gradient metasurface combined with a curved metal mirror is proposed and demonstrated. The transmissive metasurface can efficiently converge a wide-angle incident wave to a pre-designed curved metal mirror behind it with a proper distance, which acts as an effective reflective surface that can greatly enhance the backscattering of the incident wave with a wide-angle view. According to the full-wave simulations, the proposed metasurface retroreflector can perform an excellent retroreflective effect for incident microwaves of angle view between −30° and 30° range. A prototype was fabricated and the experimental results verify that the metasurface retroreflector can realize the monostatic radar cross section (RCS) enhancement with a continuous wide incident angle view from −30° to 30° at 10 GHz within a stable 3 dB RCS level. It is further demonstrated that the excellent wide-angle backscattering performance (absolute RCS enhancement value, operational bandwidth and/or incident angle view) of the proposed microwave metasurface retroreflector is competitive against the traditional trihedral corner reflector with comparable dimensions, thus opening up new possibilities to substitute the traditional bulky radar retroreflector by using a planar compact metasurface structure for microwave engineering. The presented microwave metasurface retroreflector is promising to develop into a low-profile, light weight and planar radar retroreflector which possesses tremendous RCS backscattering enhancement and wide-angle view operation range.

Dual-View Integral Imaging System With Wide Viewing Angle And High Spatial Resolution

In this paper, a dual-view integral imaging system is proposed to present two different 3D images for viewers in different viewing zones. For most of the conventional dual-view integral imaging systems, either the viewing angle or the spatial resolution of 3D image is decreased. In the proposed dual-view system, the viewing angle of each viewing zone is enlarged by introducing a switchable mask. Meanwhile, the spatial resolution of the 3D image is maintained by using the time-division multiplexing technology. A prototype of the proposed dual-view system is developed and it has wide viewing angle and high spatial resolution. The experiments coincide with the theoretical analysis.

A Robust Tracking-by-Detection Algorithm Using Adaptive Accumulated Frame Differencing and Corner Features.

We propose a tracking-by-detection algorithm to track the movements of meeting participants from an overhead camera. An advantage of using overhead cameras is that all objects can typically be seen clearly, with little occlusion; however, detecting people from a wide-angle overhead view also poses challenges such as people’s appearance significantly changing due to their position in the wide-angle image, and generally from a lack of strong image features. Our experimental datasets do not include empty meeting rooms, and this means that standard motion based detection techniques (e.g., background subtraction or consecutive frame differencing) struggle since there is no prior knowledge for a background model. Additionally, standard techniques may perform poorly when there is a wide range of movement behaviours (e.g. periods of no movement and periods of fast movement), as is often the case in meetings. Our algorithm uses a novel coarse-to-fine detection and tracking approach, combining motion detection using adaptive accumulated frame differencing (AAFD) with Shi-Tomasi corner detection. We present quantitative and qualitative evaluation which demonstrates the robustness of our method to track people in environments where object features are not clear and have similar colour to the background. We show that our approach achieves excellent performance in terms of the multiple object tracking accuracy (MOTA) metrics, and that it is particularly robust to initialisation differences when compared with baseline and state of the art trackers. Using the Online Tracking Benchmark (OTB) videos we also demonstrate that our tracker is very strong in the presence of background clutter, deformation and illumination variation.

Gbit/s ultraviolet-C diffuse-line-of-sight communication based on probabilistically shaped DMT and diversity reception.

We demonstrated a high-speed 1×2 single-input and multiple-output (SIMO) diffuse-line-of-sight (diffuse-LOS) ultraviolet-C (UVC) solar-blind communication link over a distance of 5 meters. To approach the Shannon limit and improve the spectral efficiency, we implemented probabilistically shaped discrete multitone modulation. As compared to a single-input and single-output (SISO) counterpart, we observed significant improvement in the SIMO link in terms of the angle of view of the receiver and the immunity to emulated weather condition. A wide angle of view of ± 9° is achieved in the SIMO system, with up to a 1.09-Gbit/s achievable information rate (AIR) and a minimum value of 0.24 Gbit/s. Moreover, the bit error rate of the SIMO link in emulated foggy conditions is lowered significantly when compared to that of the SISO link. This work highlights the practicality of UVC communication over realistic distances and in turbulent environments to fill the research gap in high-speed, solar-blind communication.

Construction and psychometric analysis of teachers mobile learning acceptance questionnaire

Purpose The mobile technology-pedagogy nexus has been instrumental in shifting the focus of information and communications technology in education from e-learning to mobile learning (ML). Learning with mobile technologies is more accessible, flexible, situated, personal, collaborative and lifelong. The use of technologies for educational purposes is the primary focus of higher education institutes. The successful implementation of ML rests on its acceptance by higher education teachers. It is, therefore, pertinent to determine the factors that impact higher education teachers’ acceptance of ML. This study aims to identify these factors and develop a reliable and valid instrument to measure higher education teachers’ acceptance of ML. Design/methodology/approach A sequential exploratory research design, a type of mixed method research was used for the study. A sound conceptual framework and rigorous scale development process provided the background for data collection and validation. Probability proportionate to size sampling technique was used to gather data from 212 higher education teachers from 42 higher education institutes. Teachers gave their responses on five-point Likert type items. The responses obtained were subjected to exploratory factor analysis, which provided a nine-factor solution. The factors were further validated through confirmatory factor analysis. Findings Teachers’ mobile learning (ML) acceptance questionnaire (TMLAQ), a 32-item questionnaire was developed to measure acceptance of ML among higher education teachers. A detailed literature review, interviews and focus group discussions with teachers facilitated the identification of nine constructs or antecedents of ML acceptance. These constructs were named as: perceived usefulness, ease of use, self-enhancement, constructivist belief (CB), technological barriers, attitude and behavioral intention. The scale possesses sound psychometric properties such as reliability, face validity, content validity and construct validity. Practical implications This instrument can serve as an authentic, valid and reliable measure of higher education teachers’ ML acceptance. It can be used by organizations to assess teachers’ perceptions and aid in the successful ML implementation. Originality/value There is a lack of measurement instrument that caters to wide angle view of teachers’ perception toward ML in the Indian context. This comprehensive scale will bridge this gap. Two new research constructs: CB and self-enhancement were found to be crucial from the teachers’ point of view. These constructs have not been explored in previous technology acceptance studies. To the best of the knowledge, such a comprehensive study has not been undertaken yet in the Indian context. This study can serve as a model for conducting similar kinds of studies in other developing nations.

A Real-Time Super Multiview Rendering Pipeline for Wide Viewing-Angle and High-Resolution 3D Displays Based on a Hybrid Rendering Technique

Super multiview (SMV) 3D displays with a directional diffuser can provide dense viewpoints, wide viewing angles and high image quality. However, traditional SMV 3D rendering pipelines have many disadvantages, such as high time costs, low image quality, incorrect lighting effects and limited viewing angles. To overcome the abovementioned drawbacks, we propose a new SMV 3D rendering pipeline based on a hybrid rendering technique (HRT) that effectively combines and improves the Turing multiview rendering technique, the multiple view plus depth (MVD) technique and the deferred shading technique, introducing additional normal information, diffuseness information and shininess information into the SMV 3D rendering pipeline. The SMV HRT pipeline can generate SMV 3D images with accurate lighting in real time when the viewpoint number of an SMV 3D display is greater than 50, the viewing angle is greater than 100 degrees, the resolution of a single viewpoint image is more than 512*512 and the resolution of the LCD panel is 7680*4320; in particular, complex scenes can be generated in real time. The proposed HRT pipeline is the only viable real-time rendering pipeline with accurate lighting effects for super multiview 3D displays with wide viewing angle and high resolution that runs on a common PC with standard graphics hardware. An 8k SMV 3D display with an 80° viewing angle and 100 viewpoints is applied to demonstrate the validity of the HRT method in experiments. When the number of reference views is four, the experimental results show that the rendering frame rate is more than 35 fps on average for complex virtual scenes, and the peak signal-to-noise ratio (PSNR) value of the HRT is greater than 36 dB, illustrating its high image quality and accurate lighting. Compared with state-of-the-art MVD methods, HRT processes more lighting information and is more suitable for virtual scene rendering. Therefore, the HRT method has advantages regarding the image quality of the reconstructed 3D image and can easily achieve real-time rendering for SMV 3D displays with wide viewing angles.

Radar with increased angular resolution of objects in wide-angle scanning

The parameters of radar antenna systems constructed according to the traditional scheme with phase shifters inserted both in the transmitting and receiving antenna array with the radar in which signal processing is performed only on the receiving side are considered and compared in the paper. In the second case, an additional requirement of orthogonality of the radiated signals is imposed on the radiating system of the transmitter. The characteristics of the radar with three transmitters and four receivers are compared. Two variants of forming a virtual antenna array are considered. In the first case, the radiation of the linear regular antenna array is analyzed, in the second case the thinned one, but with the same number of emitters. We demonstrate that in the second case, it is possible to implement the radar with a better angular resolution. The features of using the radar as a short-range radar for vehicle security systems with a wide-angle view are elaborated. The possibility of false capture of the target is noted. The authors of the research suggest the unambiguous direction finding method.

Three-Dimensional Ground-Based SAR Imaging Algorithm Based on Keystone Formatting and Subblock

Three-dimensional (3D) ground-based synthetic aperture radar (GB-SAR) draws attention because of the ability to obtain high accuracy 3D information of the monitoring terrain. Besides, the 3D GB-SAR system is welcome due to the flexibility and large coverage in angle and range. However, existing 3D imaging algorithms for GB-SAR data focusing have limits of high computational complexity or narrow applicable scope. To realize 3D displacement monitoring with high spatial resolution and short revisit time, in this paper, a novel 3D imaging algorithm is proposed. Based on characteristics of the model of echo data from the large range and wide-view angle scenario, the proposed method uses keystone formatting to complete range migration correction and subblocks dechirping to realize horizontal focus. With the method, the reflectivity of the monitoring scenario is obtained by only one time of linear interpolation and several times of fast Fourier transforms. The main advantages of this algorithm are high imaging precision and low computational cost, and in addition, it is applicable for large illuminating coverage including the near-field and the far-field of the radar aperture. The imaging results are sampled on pseudo-spherical grid, aiming to simplify the formulation. Finally, this method is extensively validated with simulations.

Improvement of off‐axis color shift on hybrid viewing‐angle device using dual γ‐voltage method

AbstractWe have mass production on one kind of liquid crystal display (LCD) device with hybrid viewing‐angle (HVA), which can be switched between the wide viewing‐angle (WVA) and narrow viewing‐angle (NVA) by one button. This device adopts the single cell design that with lower cost, and utilizes the optical properties of electrically tilted LC to achieve the function of NVA display. An issue has received less attention in the past and been indeed found in the production process. It is that the off‐axis color shift will appear in NVA mode. We put forward one method to improve this issue here, which is combined with the concepts of Gray Frame Insertion (GFI) and Impulse‐type driving. By switching the voltage between two different γ values, the color shift will be perfected on the produce.

Integrated infrared and visible tangential wide-angle viewing systems for surface temperature measurement and discharge monitoring in EAST

Two newly developed integrated infrared and visible tangential wide-angle (WA) viewing systems (VS) have been mounted in the Experimental Advanced Superconducting Tokamak (EAST) to provide temperature measurement and hot spot monitoring of the plasma facing components (PFC) for machine protection and further physics studies of various plasma parameters such as the scrap-off layer power fall-off length λq, the peak heat flux on the divertor target qpeak etc. The systems use endoscopes with reflective optics to obtain a wide-angle view (49.5°×62°). Via endoscope, the 3-5 μm middle wave infrared camera and the visible camera with spectral range of 400−700 nm, the WAVS could provide simultaneous real time infrared and visible image data of the first wall components in the same field of view (FOV). Some key components e.g. the 4.6 GHz lower hybrid wave (LHW) antenna, the ion cyclotron resonance frequency (ICRF) antenna, the high field side region of neutral beam injection in port F, and approximately 78° more toroidal coverage of outer divertor regions with 27° more toroidal coverage of inner divertor regions are firstly covered by the camera system. This paper presents the diagnostic description of the newly developed WAVS and preliminary experimental results observed including fast-ion losses to the inner wall during neutral beam injection (NBI), single edge localized mode (ELM) observation on upper outer divertor, hot spots on antenna guide limiters and temperature and heat flux distribution on the tungsten and graphite divertor targets in EAST.

Anterolateral Approach with Endoscopic Assistance for Resection of a Craniovertebral Junction Chordoma.

Craniovertebral junction chordomas can represent a surgical challenge, especially when intradural extension and contact with neurovascular structures is involved. To date, there is still controversy on the choice of optimal surgical corridor for such lesions, with endoscopic endonasal, far lateral and anterolateral corridors being those most commonly used. In this operative video, we present a case of craniovertebral junction chordoma with significant bone destruction and intradural extension ( Fig. 1 ). The tumor was safely removed using an anterolateral approach with transposition of the vertebral artery to gain access to the lateral craniovertebral junction. The endoscope is demonstrated to help with intradural tumor removal, providing a wide angle of view through a relatively narrow dural opening ( Fig. 2 ). In this video, nuances of the anterolateral approach, chordoma removal strategies and closure technique are presented in detail. A gross total resection was achieved, and the postoperative course was uneventful. In summary, the anterolateral approach with endoscopic assistance can offer a safe and effective corridor for the surgical management of craniovertebral junction chordomas. The link to the video can be found at: https://youtu.be/pC0YxKgNoMY .

57.5: Optimized Compensation Film for Automotive Display with Wide Viewing Angle

Wide viewing angle is a critical optical specification for liquid crystal displays (LCDs), particularly in automotive displays. We proposed an optimized compensation film which consists of a biaxial positive B film and a negative B film to improve the viewing angle of LCDs with Super Fine TFT (SFT) mode. Under optimized retardations, minimum contrast ratio in area A can tremendously reach 0.59 times of perpendicular contrast ratio which provides excellent viewing characteristics based on German OEM specification.

47.5: A new optical concept for high duty vertical alignment liquid crystal displays

Passive matrix driven vertical alignment liquid crystal displays (PMVA‐LCD) become more and more popular in many applications like industry, automotive, e‐metering, medical, sports, smart home etc. regarding its high contrast and wide view angle. However, the current solution of vertical alignment liquid crystal display has a shortcoming on the steepness of the transmissive‐voltage curve (T‐V curve) of the displays, which limits the driving duty of displays. We developped a new optical concept to achieve high duty, up to 1/128, PMVA‐LCD displays by optical‐electro simulations and experiments.

24.4: Invited Paper: The Breakthrough of large size electrical luminescence H‐Q LED TV, with 4K resolution and top emission device architecture, fabricated by ink jet printing technology

Guangdong Juhua has fabricated the world’s first 31 inch, 4K, H‐QLED TV, by using ink‐jet printing technology. The Red and Green pixel of H‐QLED TV is made from electrical luminescence quantum dot (QD for short) materials, and Blue pixel is made from soluble blue OLED material. It is a self‐emitting and top emission display with excellent performance brought by quantum dot materials, which provide large colour gamut, wider view angle, high luminance and high resolution.