7 research outputs found
Comparing Hand Gestures and a Gamepad Interface for Locomotion in Virtual Environments
Hand gesture is a new and promising interface for locomotion in virtual
environments. While several previous studies have proposed different hand
gestures for virtual locomotion, little is known about their differences in
terms of performance and user preference in virtual locomotion tasks. In the
present paper, we presented three different hand gesture interfaces and their
algorithms for locomotion, which are called the Finger Distance gesture, the
Finger Number gesture and the Finger Tapping gesture. These gestures were
inspired by previous studies of gesture-based locomotion interfaces and are
typical gestures that people are familiar with in their daily lives.
Implementing these hand gesture interfaces in the present study enabled us to
systematically compare the differences between these gestures. In addition, to
compare the usability of these gestures to locomotion interfaces using
gamepads, we also designed and implemented a gamepad interface based on the
Xbox One controller. We conducted empirical studies to compare these four
interfaces through two virtual locomotion tasks. A desktop setup was used
instead of sharing a head-mounted display among participants due to the concern
of the Covid-19 situation. Through these tasks, we assessed the performance and
user preference of these interfaces on speed control and waypoints navigation.
Results showed that user preference and performance of the Finger Distance
gesture were close to that of the gamepad interface. The Finger Number gesture
also had close performance and user preference to that of the Finger Distance
gesture. Our study demonstrates that the Finger Distance gesture and the Finger
Number gesture are very promising interfaces for virtual locomotion. We also
discuss that the Finger Tapping gesture needs further improvements before it
can be used for virtual walking
Water Quality-Based Double-Gates Control Strategy for Combined Sewer Overflows Pollution Control
The combined sewer overflows (CSO) pollution has caused many serious environmental problems, which has aroused a worldwide concern. Traditional interception-storage measures, which exhibit the disadvantages of the larger storage tank volume and the low concentration, cannot efficiently control the CSO pollution. To solve this problem, a water quality-based double-gate control strategy based on the pollution based real-time control (PBRTC) rule was proposed, and the chemical oxygen demand (COD) concentration was taken as the control index. A case study was carried out in Fuzhou, China as an example, in which the hydraulic and water quality model were constructed to evaluate two schemes. According to the results, compared to the traditional scheme, the double-gate scheme can not only reduce the storage tank volume by 1515 m3, but also increase the average COD interception rate by 1.84 times, thus ensuring the effective and stable operation of the facility. Furthermore, the traditional scheme and the double-gate scheme were evaluated under design rainfall beyond the design return period, which confirmed the high performance of the double-gate scheme in controlling CSO pollution
Highly Efficient Broadband Yellow Phosphor Based on Zero-Dimensional Tin Mixed-Halide Perovskite
Organic-inorganic hybrid metal halide perovskites have emerged as a highly promising class of light emitters, which can be used as phosphors for optically pumped white light-emitting diodes (WLEDs). By controlling the structural dimensionality, metal halide perovskites can exhibit tunable narrow and broadband emissions from the free-exciton and self-trapped excited states, respectively. Here, we report a highly efficient broadband yellow light emitter based on zero-dimensional tin mixed-halide perovskite (C4N2H14Br)4SnBrxI6-x (x = 3). This rare-earth-free ionically bonded crystalline material possesses a perfect host-dopant structure, in which the light-emitting metal halide species (SnBrxI6-x4-, x = 3) are completely isolated from each other and embedded in the wide band gap organic matrix composed of C4N2H14Br-. The strongly Stokes-shifted broadband yellow emission that peaked at 582 nm from this phosphor, which is a result of excited state structural reorganization, has an extremely large full width at half-maximum of 126 nm and a high photoluminescence quantum efficiency of ∼85% at room temperature. UV-pumped WLEDs fabricated using this yellow emitter together with a commercial europium-doped barium magnesium aluminate blue phosphor (BaMgAl10O17:Eu2+) can exhibit high color rendering indexes of up to 85
Luminescent zero-dimensional organic metal halide hybrids with near-unity quantum efficiency
Single crystalline zero-dimensional (0D) organic-inorganic hybrid materials with perfect host-guest structures have been developed as a new generation of highly efficient light emitters. Here we report a series of lead-free organic metal halide hybrids with a 0D structure, (C4N2H14X)4SnX6 (X = Br, I) and (C9NH20)2SbX5 (X = Cl), in which the individual metal halide octahedra (SnX64−) and quadrangular pyramids (SbX52−) are completely isolated from each other and surrounded by the organic ligands C4N2H14X+ and C9NH20+, respectively. The isolation of the photoactive metal halide species by the wide band gap organic ligands leads to no interaction or electronic band formation between the metal halide species, allowing the bulk materials to exhibit the intrinsic properties of the individual metal halide species. These 0D organic metal halide hybrids can also be considered as perfect host-guest systems, with the metal halide species periodically doped in the wide band gap matrix. Highly luminescent, strongly Stokes shifted broadband emissions with photoluminescence quantum efficiencies (PLQEs) of close to unity were realized, as a result of excited state structural reorganization of the individual metal halide species. Our discovery of highly luminescent single crystalline 0D organic-inorganic hybrid materials as perfect host-guest systems opens up a new paradigm in functional materials design
Highly Efficient Broadband Yellow Phosphor Based on Zero-Dimensional Tin Mixed-Halide Perovskite
Organic–inorganic
hybrid metal halide perovskites have emerged as a highly promising
class of light emitters, which can be used as phosphors for optically
pumped white light-emitting diodes (WLEDs). By controlling the structural
dimensionality, metal halide perovskites can exhibit tunable narrow
and broadband emissions from the free-exciton and self-trapped excited
states, respectively. Here, we report a highly efficient broadband
yellow light emitter based on zero-dimensional tin mixed-halide perovskite
(C<sub>4</sub>N<sub>2</sub>H<sub>14</sub>Br)<sub>4</sub>SnBr<sub><i>x</i></sub>I<sub>6–<i>x</i></sub> (<i>x</i> = 3). This rare-earth-free ionically bonded crystalline
material possesses a perfect host-dopant structure, in which the light-emitting
metal halide species (SnBr<sub><i>x</i></sub>I<sub>6–<i>x</i></sub><sup>4–</sup>, <i>x</i> = 3) are
completely isolated from each other and embedded in the wide band
gap organic matrix composed of C<sub>4</sub>N<sub>2</sub>H<sub>14</sub>Br<sup>–</sup>. The strongly Stokes-shifted broadband yellow
emission that peaked at 582 nm from this phosphor, which is a result
of excited state structural reorganization, has an extremely large
full width at half-maximum of 126 nm and a high photoluminescence
quantum efficiency of ∼85% at room temperature. UV-pumped WLEDs
fabricated using this yellow emitter together with a commercial europium-doped
barium magnesium aluminate blue phosphor (BaMgAl<sub>10</sub>O<sub>17</sub>:Eu<sup>2+</sup>) can exhibit high color rendering indexes
of up to 85