Solid reconstruction using recognition of quadric surfaces from orthographic views

International audienceThe reconstruction of 3D objects from 2D orthographic views is crucial for maintaining and further developing existing product designs. A B-rep oriented method for reconstructing curved objects from three orthographic views is presented by employing a hybrid wire-frame in place of an intermediate wire-frame. The Link-Relation Graph (LRG) is introduced as a multi-graph representation of orthographic views, and quadric surface features (QSFs) are defined by special basic patterns of LRG as well as aggregation rules. By hint-based pattern matching in the LRGs of three orthographic views in an order of priority, the corresponding QSFs are recognized, and the geometry and topology of quadric surfaces are recovered simultaneously. This method can handle objects with interacting quadric surfaces and avoids the combinatorial search for tracing all the quadric surfaces in an intermediate wire-frame by the existing methods. Several examples are provided

Converting Hybrid Wire-frames to B-rep Models

International audienceSolid reconstruction from engineering drawings is one of the efficient technologies to product solid models. The B-rep oriented approach provides a practical way for reconstructing a wide range of objects. However, its major limitation is the computational complexity involved in the search for all valid faces from the intermediate wire-frame, especially for objects with complicated face topologies. In previous work, we presented a hint-based algorithm to recognize quadric surfaces from orthographic views and generate a hybrid wire-frame as the intermediate model of our B-rep oriented method. As a key stage in the process of solid reconstructing, we propose an algorithm to convert the hybrid wire-frame to the final B-rep model by extracting all the rest faces of planes based on graph theory. The entities lying on the same planar surface are first collected in a plane graph. After all the cycles are traced in a simplified edge-adjacency matrix of the graph, the face loops of the plane are formed by testing loop containment and assigning loop directions. Finally, the B-rep model is constructed by sewing all the plane faces based on the M¨obius rule. The method can efficiently construct 2- manifold objects with a variety of face topologies, which is illustrated by results of implementatio

Recent Recovery of the World’s Rarest Primate Is Not Directly Linked to Increasing Habitat Quality

Due to habitat loss and hunting, the Hainan gibbon (Nomascus hainanus), the world’s rarest primate, was reduced to only two social groups and seven known individuals in 1978. Following the establishment of Bawangling National Natural Reserve (BNNR), gibbon forest habitat increased within this landscape from 56 km2 in 1980 to 300 km2, and the species had increased to five groups and 35 individuals by 2021. It is important to assess whether the large increase in habitat area was responsible for gibbon population increase, or whether gibbon recovery was associated with other factors. Here we use a 21-year longitudinal dataset of Hainan gibbon population change and habitat change, combined with vegetation survey plot data for 2021, to establish an accurate distribution baseline for natural tropical broadleaf forest across the BNNR landscape from 400 to 1300 m (the elevational range of gibbons at BNNR) and within the home range for each of the five Hainan gibbon social groups. We then utilized Landsat time-series images and analysis to compute non-linear causal relationships between forest dynamics and gibbon population growth from 2000 to 2021, both across BNNR and within each gibbon group home range. Metrics of forest dynamics include change in total forest area and forest fragmentation, and metrics of gibbon population dynamics include variation in total number of individuals for the entire population and within each social group, and variation in total number of groups. Our results demonstrate that overall gibbon population growth shows a positive relationship with improved habitat quality, with a one-year time lag of population response. However, changes in numbers of individuals within social groups do not show a similar relationship with improving habitat quality, suggesting that increasing forest cover and connectivity within the BNNR landscape are not direct determinants of Hainan gibbon recovery and that other environmental and/or anthropogenic factors are likely to be involved

PS-PVD thermal/environmental barrier coatings with novel microstructures

Plasma spray physical vapor deposition (PS-PVD) technology has attracted increasing attention due to it promising potential in processing advanced functional coatings such as thermal/environmental barrier coatings (TBCs) by flexibly tailoring the coating microstructure architecture in a broad range. In this work, yttria stabilized zirconia (YSZ) TBCs with a novel quasi-columnar structure was prepared by co-deposition of vapor phase and nano-clusters using PS-PVD and the associated deposition mechanism was discussed. The thermo-physical and mechanical properties, sintering resistance and thermal shock life of the coating were investigated. The thermal conductivity is in a range of 0.7~1.0 W/mk between 200 °C and 1200 °C and the average life is ~4000 cycles during thermal shock testing in which the coating surface was heated to 1200 °C within 20 s and held at the temperature for 5 min by gas flame. Noted that the quasi-columnar TBC revealed much better resistance to glassy CaO-MgO-Al2O3-SiO2 (CMAS) adsorption than those TBCs produced by air plasma spray (APS) and electron beam physical vapor deposition (EB-PVD) and some attempts were made to understand the related mechanisms. Ytterbium silicate/mullite/Si environmental barrier coatings (EBCs) were sprayed onto SiC ceramic matrix composites (CMC) by PS-PVD. The dense ytterbium silicate coating deposited at 65 kw is mainly composed of ytterbium disilicate resulting from vapor-phase deposition, whereas the layered coating at 40 kw is mainly ytterbium monosilicate from liquid deposition

Overcoming the Circular Problem for \gamma-ray Bursts in Cosmological Global Fitting Analysis

Due to the lack of low redshift long Gamma-Ray Bursts (GRBs), the circular problem has been a severe obstacle for using GRBs as cosmological candles. In this paper, we present a new method to deal with such a problem in MCMC global fitting analysis. Assuming that a certain type of correlations between different observables exists in a subsample of GRBs, for the parameters involved in the correlation relation, we treat them as free parameters and determine them simultaneously with cosmological parameters through MCMC analysis on GRB data together with other observational data. Then the circular problem is naturally eliminated in this procedure. We take the Ghirlanda relation as an example while keeping in mind the debate about its physical validity. Together with SNe Ia, WMAP and SDSS data, we include 27 GRBs with the reported Ghirlanda relation in our study, and perform MCMC global fitting. We consider the $\Lambda$CDM model and dynamical dark energy models. In each case, in addition to the constraints on the relevant cosmological parameters, we obtain the best fit values as well as the distributions of the correlation parameters $A$ and $C$. We find that the observational data sets other than GRBs can affect $A$ and $C$ considerably through their degeneracies with the cosmological parameters. The results on $A$ and $C$ for different cosmological models are in well agreement within $1\sigma$ range. The best fit value of $A$ in all models being analyzed is $A\sim 1.53$ with $\sigma \sim 0.08$. For $C$, we have the best value in the range of $0.94-0.98$ with $\sigma\sim 0.1$. It is also noted that the distributions of $A$ and $C$ are generally broader than the priors used in many studies in literature. (Abriged)Comment: 9 pages, 2 figures, 2 tables, Accepted for publication in Ap

HutZ is required for biofilm formation and contributes to the pathogenicity of Edwardsiella piscicida

International audienceAbstractEdwardsiella piscicida is a severe fish pathogen. Haem utilization systems play an important role in bacterial adversity adaptation and pathogenicity. In this study, a speculative haem utilization protein, HutZEp, was characterized in E. piscicida. hutZEp is encoded with two other genes, hutW and hutX, in an operon that is similar to the haem utilization operon hutWXZ identified in V. cholerae. However, protein activity analysis showed that HutZEp is probably not related to hemin utilization. To explore the biological role of HutZEp, a markerless hutZEp in-frame mutant strain, TX01ΔhutZ, was constructed. Deletion of hutZEp did not significantly affect bacterial growth in normal medium, in iron-deficient conditions, or in the presence of haem but significantly retarded bacterial biofilm growth. The expression of known genes related to biofilm growth was not affected by hutZEp deletion, which indicated that HutZEp was probably a novel factor promoting biofilm formation in E. piscicida. Compared to the wild-type TX01, TX01ΔhutZ exhibited markedly compromised tolerance to acid stress and host serum stress. Pathogenicity analysis showed that inactivation of hutZEp significantly impaired the ability of E. piscicida to invade and reproduce in host cells and to infect host tissue. In contrast to TX01, TX01ΔhutZ was defective in blocking host macrophage activation. The expression of hutZEp was directly regulated by the ferric uptake regulator Fur. This study is the first functional characterization of HutZ in a fish pathogen, and these findings suggested that HutZEp is essential for E. piscicida biofilm formation and contributes to host infection

The Design and Implementation of the Defender Cloud on TWAREN Backbone

Defender Cloud is a cloud based backbone network defending system having full scope over the whole backbone network. Rather than detecting suspicious network activities on a local area network, it collects and integrates the flow data from all connecting members and all entrances of a backbone network. After analyzing by a proposed cloud based distributed processing model, the corresponding defensive reaction can be carried out in a global basis. Thus its protection can cover the whole network, even including member institutions without their own firewall. This paper illustrates the design, verification and future perspective of the Defender Cloud, with an emphasis on the distributed processing of the flow data

Layer-dependent transport properties in the Moir\'e of strained homobilayer transition metal dichalcogenides

Bilayer moir\'e structures have attracted significant attention recently due to their spatially modulated layer degrees of freedom. However, the layer-dependent transport mechanism in the moir\'e structures is still a problem to be explored. Here we investigate the layer-dependent transport properties regulated by the strain, the interlayer bias and the number of moir\'e periods in a strained moir\'e homobilayer TMDs nanoribbon based on low-energy efficient models. The charge carriers can pass perfectly through the scattering region with the moir\'e potential. While, it is noted that the overall transmission coefficient is mainly contributed from either intralayer or interlayer transmissions. The transition of transport mechanism between intralayer and interlayer transmissions can be achieved by adjusting the strain. The intralayer transmissions are suppressed and one of the interlayer transmissions can be selected by a vertical external electric field, which can cause a controllable layer polarization. Moreover, the staggered intralayer and interlayer minigaps are formed as the number of moir\'e periods increases in the scattering region due to the overlap of the wave functions in two adjacent moir\'e periods. Our finding points to an opportunity to realize layer functionalities by the strain and electric field.Comment: 6 pages, 4 figure