850 research outputs found
Boundary behaviour of the unique solution to a singular Dirichlet problem with a convection term
AbstractBy Karamata regular variation theory and constructing comparison functions, we derive that the boundary behaviour of the unique solution to a singular Dirichlet problem −Δu=b(x)g(u)+λ|∇u|q, u>0, x∈Ω, u|∂Ω=0, which is independent of λ|∇uλ|q, where Ω is a bounded domain with smooth boundary in RN, λ∈R, q∈(0,2], lims→0+g(s)=+∞, and b is non-negative on Ω, which may be vanishing on the boundary
Stochastically Ultimate Boundedness and Global Attraction of Positive Solution for a Stochastic Competitive System
The 3-dimensional printing for dental tissue regeneration: the state of the art and future challenges
Tooth loss or damage poses great threaten to oral and general health. While contemporary clinical treatments have enabled tooth restoration to a certain extent, achieving functional tooth regeneration remains a challenging task due to the intricate and hierarchically organized architecture of teeth. The past few decades have seen a rapid development of three-dimensional (3D) printing technology, which has provided new breakthroughs in the field of tissue engineering and regenerative dentistry. This review outlined the bioactive materials and stem/progenitor cells used in dental regeneration, summarized recent advancements in the application of 3D printing technology for tooth and tooth-supporting tissue regeneration, including dental pulp, dentin, periodontal ligament, alveolar bone and so on. It also discussed current obstacles and potential future directions, aiming to inspire innovative ideas and encourage further development in regenerative medicine
Demonstration of Low Voltage and Functionally Complete Logic Operations Using Body-Biased Complementary and Ultra-Thin ALN Piezoelectric Mechanical Switches
This paper reports, for the first time, on the demonstration of low voltage and functionally complete logic elements (NAND and NOR) implemented by using body-biased complementary and ultra-thin (250 nm thick) Aluminum Nitride (AlN) based piezoelectric mechanical switches. This work presents, firstly, the importance of scaling AlN films for the demonstration of ultra-thin AlN switches and, secondly, the implementation of a new actuation scheme based on body biasing to lower the switch threshold voltage. Four of these ultra-thin switches were connected together to synthesize functionally complete MEMS logic gates (NAND and NOR) with a ± 2V swing and a body-bias voltage \u3c 8 V
Quantifying Spatiotemporal Dynamics of Solar Radiation over the Northeast China Based on ACO-BPNN Model and Intensity Analysis
Reliable information on the spatiotemporal dynamics of solar radiation plays a crucial role in studies relating to global climate change. In this study, a new backpropagation neural network (BPNN) model optimized with an Ant Colony Optimization (ACO) algorithm was developed to generate the ACO-BPNN model, which had demonstrated superior performance for simulating solar radiation compared to traditional BPNN modelling, for Northeast China. On this basis, we applied an intensity analysis to investigate the spatiotemporal variation of solar radiation from 1982 to 2010 over the study region at three levels: interval, category, and conversion. Research findings revealed that (1) the solar radiation resource in the study region increased from the 1980s to the 2000s and the average annual rate of variation from the 1980s to the 1990s was lower than that from the 1990s to the 2000s and (2) the gains and losses of solar radiation at each level were in different conditions. The poor, normal, and comparatively abundant levels were transferred to higher levels, whereas the abundant level was transferred to lower levels. We believe our findings contribute to implementing ad hoc energy management strategies to optimize the use of solar radiation resources and provide scientific suggestions for policy planning
Magnetic band representations, Fu-Kane-like symmetry indicators and magnetic topological materials
To realize novel topological phases and to pursue potential applications in
low-energy consumption spintronics, the study of magnetic topological materials
is of great interest. Starting from the theory of nonmagnetic topological
quantum chemistry [Bradlyn et al., Nature 547, 298 (2017)], we have obtained
irreducible (co)representations and compatibility relations (CRs) in momentum
space, and we constructed a complete list of magnetic band (co)representations
(MBRs) in real space for other MSGs with anti-unitary symmetries (i.e. type-III
and type-IV MSGs). The results are consistent with the magnetic topological
quantum chemistry [Elcoro et al., Nat. Comm. 12, 5965 (2021)]. Using the CRs
and MBRs, we reproduce the symmetry-based classifications for MSGs, and we
obtain a set of Fu-Kane-like formulas of symmetry indicators (SIs) in both
spinless (bosonic) and spinful (fermionic) systems, which are implemented in an
automatic code - TopMat - to diagnose topological magnetic materials. The
magnetic topological materials, whose occupied states can not be decomposed
into a sum of MBRs, are consistent with nonzero SIs. Lastly, using our online
code, we have performed spin-polarized calculations for magnetic compounds in
the materials database and find many magnetic topological candidates.Comment: 6 pages, 3128 pages for the Appendice
Body-Biased Complementary Logic Implemented Using AIN Piezoelectric MEMS Switches
This paper reports on the first implementation of low voltage complementary logic (\u3c 1.5 V) by using body-biased aluminum nitride (AlN) piezoelectric MEMS switches. For the first time, by using opposite body biases the same mechanical switch has been made to operate as both an ntype and p-type (complementary) device. Body-biasing also gives the ability to precisely tune the threshold voltage of a switch. The AlN MEMS switches have shown extremely small subthreshold slopes and threshold voltages as low as 0.8 mV/dec and 30 mV, respectively. Furthermore, this work presents a fully mechanical body-biased inverter formed by two AlN MEMS switches operating at 100 Hz with a ± 1.5 V voltage swing
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