Unique porous ZnS-CdS-CoSx Reuleaux triangle nanosheets were prepared via a bimetallic precursor and ion-exchange process, achieving efficient photocatalytic H2 production due to the synergistic ...effect of Z-scheme heterojunction and vacancy defects.
Display omitted
•Porous ZnS-CdS-CoSx Reuleaux triangle nanosheets are first reported.•Z-scheme heterojunction and S, Zn vacancies enable efficient charge separation.•CoSx provides abundant S22- species as active sites for H2 production.•Excellent HER rate (53.43 mmol·g−1·h−1) and AQE (30.8 % at 420 nm) are obtained.•Prominent H2-evolving stability attested by cycling and long-term tests.
Photocatalytic water-splitting employing Z-scheme semiconductor heterojunction is a promising avenue to realize the efficient conversion and storage of renewable solar energy because of its space-separated reduction and oxidation sites, effective charge separation and transportation, as well as the stronger redox abilities of photogenerated carriers. Nevertheless, the efficiency of Z-scheme photocatalysts is often weakened by the insufficient coupling of components due to the stepwise hybridization processes. In this work, unique ZnS-CdS-CoSx porous Reuleaux triangle nanosheets with intimate Z-scheme hetero-interface and S, Zn vacancies were produced by using Zn2Co3(OH)10·2H2O as the bimetallic precursor for subsequent sulfurization and Cd2+-exchange reaction. Noticeably, such a novel structure shows desirable features which suggest a promising photocatalyst for visible-light photocatalytic H2 evolution, including superior charge-separating capability enabled by the Z-scheme charge transfer and synergetic charge-trapping effect of S, Zn vacancies, excellent light-harvesting capacity, abundant S22− species as H2-evolving active sites, a large surface area, and good stability without obvious decline in activity after multiple cycling and long-term tests. The ZnS-CdS-CoSx heterojunction exhibits an outstanding visible-light-driven H2-evolving activity as high as 53.43 mmol·g−1·h−1, corresponding to a high apparent quantum efficiency of 30.8 % at 420 nm, far better than that of Pt-loaded CdS and a great deal of CdS-based photocatalysts reported in the literatures. The present work may shed new light on the designed synthesis of high-performance semiconductor heterojunction for sustainable solar utilization and environmental remediation.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sensing coverage is an essential functionality of wireless sensor networks (WSNs). However, it is also well known that coverage alone in WSNs is not sufficient, and hence network connectivity should ...also be considered for the correct operation of WSNs. In this paper, we address the problem of k-coverage in WSNs such that in each scheduling round, every location in a monitored field (or simply field) is covered by at least k active sensors while all active sensors are being connected. Precisely, we study sensors duty-cycling strategies for generating k-coverage configurations in WSNs. First, we model the k-coverage problem in WSNs. Second, we derive a sufficient condition of the sensor spatial density for complete k-coverage of a field. We also provide a relationship between the communication and sensing ranges of sensors to maintain both k-coverage of a field and connectivity among all active sensors. Third, we propose four configuration protocols to solve the problem of k-coverage in WSNs. We prove that our protocols select a minimum number of sensors to achieve full k-coverage of a field while guaranteeing connectivity between them. Then, we relax some widely used assumptions for coverage configuration in WSNs, to promote the use of our proposed protocols in real-world sensing applications. Our simulation results show that our protocols outperform an existing distributed k-coverage configuration protocol.
Condenser capacity and hyperbolic diameter Nasser, Mohamed M.S.; Rainio, Oona; Vuorinen, Matti
Journal of mathematical analysis and applications,
04/2022, Volume:
508, Issue:
1
Journal Article
Peer reviewed
Open access
Given a compact connected set E in the unit disk B2, we give a new upper bound for the conformal capacity of the condenser (B2,E) in terms of the hyperbolic diameter t of E. Moreover, for t>0, we ...construct a set of hyperbolic diameter t and apply novel numerical methods to show that it has larger capacity than a hyperbolic disk with the same diameter. The set we construct is called a Reuleaux triangle in hyperbolic geometry and it has constant hyperbolic width equal to t.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper, we introduce the Minkowski measure of asymmetry for the spherical bodies of constant width. Then we prove that the spherical balls are the most symmetric bodies among all spherical ...bodies of constant width, and the completion of the spherical regular simplexes are the most asymmetric bodies.
We discuss the Schwarz problem on Reuleaux triangle. By the technique of parqueting reflection principle, we translate the Schwarz problem into a Riemann boundary value problem on a system of arcs. ...We first state that the Riemann problem is solvable, while the solutions are represented by a Cauchy type integral. At last, as the main theorem, we prove that those two problems are equivalent to each other. And then we obtain the explicit integral representation of the solution to a Schwarz problem.
Full text
Available for:
BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
This paper presents the design, modeling, analysis, and experimental results of a novel bipedal robotic system that utilizes two interconnected single degree-of-freedom (DOF) leg mechanisms to ...produce stable forward locomotion and steering. The single DOF leg is actuated via a Reuleaux triangle cam-follower mechanism to produce a constant body height foot trajectory. Kinematic analysis and dimension selection of the Reuleaux triangle mechanism is conducted first to generate the desired step height and step length. Leg sequencing is then designed to allow the robot to maintain a constant body height and forward walking velocity. Dynamic simulations and experiments are conducted to evaluate the walking and steering performance. The results show that the robot is able to control its body orientation, maintain a constant body height, and achieve quasi-static locomotion stability.
An analytical model of a partly-filled tank of arbitrary cross-section is developed for predicting transient lateral slosh force and overturning moment using linear slosh theory. Slosh frequencies ...and mode shapes are initially estimated using the variational method, which is applied to the linearized free-surface boundary condition. The resulting truncated system of linear ordinary differential equations is subsequently solved numerically to determine the fluid velocity potentials followed by hydrodynamic force and moment. The validity of the model is examined through comparisons with available analytical solutions and experimental data. The slosh force and roll moment are obtained for four different tank cross-sections, namely, circular, elliptical, modified-oval and Reuleaux-triangle. It is shown that the magnitudes of the slosh force and overturning moment are strongly dependent upon the tank cross-section. The slosh model is subsequently integrated to a roll plane model of an articulated tank-semitrailer vehicle to study the effect of dynamic liquid slosh as well as the tank cross-section on the steady-turning roll stability limit of the vehicle under constant and variable cargo load conditions. The results suggest that a tank cross-section with lower overall center of mass and lower critical slosh length yields an enhanced roll stability limit under medium- and high-fill conditions.
•An analytical model of lateral slosh is developed using the linear slosh theory.•The model is applicable to tanks with arbitrary cross-sections and liquid depths.•Effectiveness of Reuleaux-triangle tank in suppressing the liquid slosh is shown.•Rollover limits are much lower than those of the widely-used quasi-static analysis.•Highest rollover limits are obtained for vehicle with the Reuleaux-triangle tank.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this paper, we consider the Groemer–Wallen measure of asymmetry for Reuleaux polygons, and show that the
n
-th (
n
≥
5
,
n
odd
) regular Reuleaux polygons are the most symmetric among all
n
-th ...Reuleaux polygons.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
PDF
