153 research outputs found
Bilayer Kagome Borophene with Multiple van Hove Singularities
The appearance of van Hove singularities near the Fermi level leads to
prominent phenomena, including superconductivity, charge density wave, and
ferromagnetism. Here a bilayer Kagome lattice with multiple van Hove
singularities is designed and a novel borophene with such lattice
(BK-borophene) is proposed by the first-principles calculations. BK-borophene,
which is formed via three-center two-electron (3c-2e) sigma-type bonds, is
predicted to be energetically, dynamically, thermodynamically, and mechanically
stable. The electronic structure hosts both conventional and high-order van
Hove singularities in one band. The conventional van Hove singularity resulting
from the horse saddle is 0.065 eV lower than the Fermi level, while the
high-order one resulting from the monkey saddle is 0.385 eV below the Fermi
level. Both the singularities lead to the divergence of electronic density of
states. Besides, the high-order singularity is just intersected to a Dirac-like
cone, where the Fermi velocity can reach 1340000 m/s. The interaction between
the two Kagome lattices is critical for the appearance of high-order van Hove
singularities. The novel bilayer Kagome borophene with rich and intriguing
electronic structure offers an unprecedented platform for studying correlation
phenomena in quantum material systems and beyond
DCSG: Unsupervised Learning of Compact CSG Trees with Dual Complements and Dropouts
We present DCSG, a neural model composed of two dual and complementary
network branches, with dropouts, for unsupervised learning of compact
constructive solid geometry (CSG) representations of 3D CAD shapes. Our network
is trained to reconstruct a 3D shape by a fixed-order assembly of quadric
primitives, with both branches producing a union of primitive intersections or
inverses. A key difference between DCSG and all prior neural CSG models is
its dedicated residual branch to assemble the potentially complex shape
complement, which is subtracted from an overall shape modeled by the cover
branch. With the shape complements, our network is provably general, while the
weight dropout further improves compactness of the CSG tree by removing
redundant primitives. We demonstrate both quantitatively and qualitatively that
DCSG produces compact CSG reconstructions with superior quality and more
natural primitives than all existing alternatives, especially over complex and
high-genus CAD shapes.Comment: 9 page
A Novel Dynamic Measurement System for Evaluating the Braking Coordination of Articulated Vehicles
The braking coordination between tractor and semitrailer is vital to the safety of articulated vehicles. Traditional evaluation about braking coordination is based on the pressure measurement along air braking pipeline, which needs to change original braking structure to install gauges and cannot directly reflect the final braking coordination of different wheels. To overcome these limitations, this paper proposes a novel dynamic measurement system for evaluating the braking coordination of articulated vehicles. During the brake test, all wheel velocities of the whole articulated vehicle are synchronously obtained through a specially designed distributed acquisition platform. To effectively eliminate gross errors and noises in wheel angular velocity data, a 3-order autoregressive (AR) model and an improved-thresholding wavelet filtering algorithm are developed. Further, a novel direct evaluation method about braking coordination is proposed according to the differences in angular velocity dropping time of all wheels. Finally, the overall system is assessed through real field tests. The results validate the feasibility and effectiveness of the proposed system
Scalable Scheduling for Industrial Time-Sensitive Networking: A Hyper-flow Graph Based Scheme
Industrial Time-Sensitive Networking (TSN) provides deterministic mechanisms
for real-time and reliable flow transmission. Increasing attention has been
paid to efficient scheduling for time-sensitive flows with stringent
requirements such as ultra-low latency and jitter. In TSN, the fine-grained
traffic shaping protocol, cyclic queuing and forwarding (CQF), eliminates
uncertain delay and frame loss by cyclic traffic forwarding and queuing.
However, it inevitably causes high scheduling complexity. Moreover, complexity
is quite sensitive to flow attributes and network scale. The problem stems in
part from the lack of an attribute mining mechanism in existing frame-based
scheduling. For time-critical industrial networks with large-scale complex
flows, a so-called hyper-flow graph based scheduling scheme is proposed to
improve the scheduling scalability in terms of schedulability, scheduling
efficiency and latency & jitter. The hyper-flow graph is built by aggregating
similar flow sets as hyper-flow nodes and designing a hierarchical scheduling
framework. The flow attribute-sensitive scheduling information is embedded into
the condensed maximal cliques, and reverse maps them precisely to congestion
flow portions for re-scheduling. Its parallel scheduling reduces network scale
induced complexity. Further, this scheme is designed in its entirety as a
comprehensive scheduling algorithm GH^2. It improves the three criteria of
scalability along a Pareto front. Extensive simulation studies demonstrate its
superiority. Notably, GH^2 is verified its scheduling stability with a runtime
of less than 100 ms for 1000 flows and near 1/430 of the SOTA FITS method for
2000 flows
Characteristic on the Stability of <em>Haloxylon ammodendron</em> Plantation in the Southern Fringe of Gurbantunggut Desert, Northwest China
Using chronosequence theory and method, the characteristics of vegetation-soil coupling and structure stability of Haloxylon ammodendron plantations in the southern fringe of Gurbantunggut Desert were analyzed. The results showed, the canopy storey of H. ammodendron plantation experienced three stages, rapid growth (the age of 7 to 20), then slow growth (the age of 20 to 28) and last decline (over the age of 28). The best natural regeneration started from 17-yr-old plantation. Vegetation-soil system coupling degree (C) and coupling coordinative degree (D) of plantations with different age were not one-to-one correspondence. The system of H. ammodendron plantations always stayed in disorder recession, vegetation and soil were prone to loss type during the process of sand-fixation. Five principal components evaluated that the first rank was 42-yr-old plantation. It was inferred that the trend of the vegetation and soil system was from senescence to harmonious development. So the trend of coordinated development between vegetation and soil would be promoted, if the artificial tending and management measures strengthened
Construction and Characterization of a Chimeric Virus (BIV/HIV-1) Carrying the Bovine Immunodeficiency Virus \u3ci\u3egag\u3c/i\u3e-\u3ci\u3epol\u3c/i\u3e Gene: Research Letters
HIV-1HXB2 5′LTR region, most of BIVR29 gag-pol segment and HIV-1HXB2 pol IN-3′LTR region were respectively amplified. A chimeric clone, designated as pHBIV3753, was constructed by cloning three fragments sequentially into pUC18. MT4 cells were transfected with pHBIV3753. The replication and expressions of the chimeric virus (HBIV3753) were monitored by RT activity and IFA. The results firstly demonstrated that it is possible to generate a new type of the BIV/HIV-1 chimeric virus containing BIV gag-pol gene
Genome-Wide Expression Analysis in Down Syndrome: Insight into Immunodeficiency
Down syndrome (DS) is caused by triplication of Human chromosome 21 (Hsa21) and associated with an array of deleterious phenotypes, including mental retardation, heart defects and immunodeficiency. Genome-wide expression patterns of uncultured peripheral blood cells are useful to understanding of DS-associated immune dysfunction. We used a Human Exon microarray to characterize gene expression in uncultured peripheral blood cells derived from DS individuals and age-matched controls from two age groups: neonate (N) and child (C). A total of 174 transcript clusters (gene-level) with eight located on Hsa21 in N group and 383 transcript clusters including 56 on Hsa21 in C group were significantly dysregulated in DS individuals. Microarray data were validated by quantitative polymerase chain reaction. Functional analysis revealed that the dysregulated genes in DS were significantly enriched in two and six KEGG pathways in N and C group, respectively. These pathways included leukocyte trans-endothelial migration, B cell receptor signaling pathway and primary immunodeficiency, etc., which causally implicated dysfunctional immunity in DS. Our results provided a comprehensive picture of gene expression patterns in DS at the two developmental stages and pointed towards candidate genes and molecular pathways potentially associated with the immune dysfunction in DS
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