Three-dimensional inversion of knot defects recognition in timber cutting

The comprehensive utilization of wood is the main goal of log cutting,but knot defects increase the diffi-culty of rationally optimizing cutting.Due to the lack of real shape data of knot defects in logs,it is diffi cult for detection methods to establish a correlation between signal and defect morphology.An image-processing method is proposed for knot inversion based on distance regularized level set segmentation(DRLSE)and spatial vertex clustering,and with the inversion of the defects existing relative board position in the log,an inversion model of the knot defect is established.First,the defect edges of the top and bottom images of the boards are extracted by DRLSE and ellipse fi tting,and the major axes of the ellipses made coplanar by angle correction;second,the coordinate points of the top and bottom ellipse edges are extracted to form a spatial straight line;third,to solve the intersection dispersion of spatial straight lines and the major axis plane,K-medoids clustering is used to locate the vertex.Finally,with the vertex and the large ellipse,a 3D cone model is constructed which can be used to invert the shape of knots in the board.The experiment was conducted on ten defective larch boards,and the experimental results showed that this method can accurately invert the shapes of defects in solid wood boards with the advantages of low cost and easy operation.

A novel NIRS modelling method with OPLS-SPA and MIX-PLS for timber evaluation

The identification of timber properties is important for safe application.Near Infrared Spectroscopy(NIRS)technology is widely-used because of its simplicity,efficiency,and positive environmental attributes.However,in its application,weak signals are extracted from complex,overlapping and changing information.This study focused on the stability of NIR modeling.The Orthogonal Partial Least Squares(OPLS)and Successive Projections Algorithm(SPA)eliminates noise and extracts effective spectra,and an ensemble learning method MIX-PLS,is applied to establish the model.The elastic modulus of timber is taken as an example,and 201 wood samples of three species,Xylosmacongesta(Lour.)Merr.,Acer pictum subsp.mono,and Betula pendula,samples were divided into three groups to investigate modelling performance.The results show that OPLS can preprocess the near-infrared spectroscopy information according to the target object in the face of the system error and reduce errors to minimum.SPA finally selects 13 spectral bands,simplifies the NIR spectral data and improves model accuracy.The Pearson's correlation coefficient of Calibration(Rc)and the Pearson's correlation coefficient of Prediction(Rp)of Mix Partial Least Squares(MIX-PLS)were 0.95 and 0.90,and Root Mean Square Error of Calibration(RMSEC)and Root Mean Square Error of Prediction(RMSEP)are 2.075 and 6.001,respectively,which shows the model has good generalization abilities.

Development of an Inexpensive Decentralized Autonomous Aquatic Craft Swarm System for Ocean Exploration

Swarm robotics in maritime engineering is a promising approach characterized by large numbers of relatively small and inexpensive autonomous aquatic crafts (AACs) to monitor marine environments. Compared with a single, large aquatic manned or unmanned surface vehicle, a highly distributed aquatic swarm system with several AACs features advantages in numerous real-world maritime missions, and its natural potential is qualified for new classes of tasks that uniformly feature low cost and high efficiency through time. This article develops an inexpensive AAC based on an embedded-systemcompanion computer and open-source autopilot, providing a verification platform for education and research on swarm algorithm on water surfaces. A topology communication network, including an inner communication network to exchange information among AACs and an external communication network for monitoring the state of the AAC Swarm System (AACSS), was designed based on the topology built into the Xbee units for the AACSS. In the emergence control network, the transmitter and receiver were coupled to distribute or recover the AAC. The swarm motion behaviors in AAC were resolved into the capabilities of go-to-waypoint and path following, which can be accomplished by two uncoupled controllers: speed controller and heading controller. The good performance of velocity and heading controllers in go-to-waypoint was proven in a series of simulations. Path following was achieved by tracking a set of ordered waypoints in the go-to-waypoint. Finally, a sea trial conducted at the China National Deep Sea Center successfully demonstrated the motion capability of the AAC. The sea trial results showed that the AAC is suited to carry out environmental monitoring tasks by efficiently covering the desired path, allowing for redundancy in the data collection process and tolerating the individual AACs’ path-following offset caused by winds and waves.

Spectra properties of Yb^(3+),Er^(3+):Sc_2SiO_5 crystal

The influence of Er3+ ions on the spectra of Yb^(3+),Er^(3+): Sc_2 SiO_5(SSO) single crystal, which was obtained by Czochralski(Cz) method, is discussed. The absorption coefficient at 980 nm was 13.36 cm^(-1) with a peak absorption cross-section of 1.46 × 10^(-20) cm2. The emission cross-sections at 1034 nm and 1062 nm were 5.5 × 10^(-21) cm^2 and4.9 × 10^(-21) cm^2, respectively. The fluorescence lifetime was estimated as 1.24 ms at 1061 nm. The mechanical properties of SSO single crystal were also presented.

氨基端不同二级结构的丙型肝炎病毒NS3／4A复合体的丝氨酸酶活性差异研究

目的探讨表达不同氨基端二级结构的丙型肝炎病毒非结构蛋白3／4A（HCVNS3／4A）各亚型丝氨酸酶活性及其对宿主细胞功能抑制作用的差异。方法以pSGS／M。HOS-5／4A为模板（A1-1），构建表达不同氨基端二级结构NS3／4A的点突变质粒，并分别命名为A1-2，A2-1，A2-2，B1-1，B1-2，B2-1，B2-2。Western印迹检测所有构建质粒的表达及各亚型顺式及反式NS3蛋白酶活性的差异。荧光素酶报告试验检测pSGS／M-H05-5／4A各个二级结构亚型对干扰素-β（IFN-β）产生及p53依赖的荧光素酶基因的转录活性的抑制作用以及各亚型之间抑制作用的差异。结果Western印迹显示所有构建质粒均成功表达，而且A2-1和B2-1亚型NS3／4A存在不完全切割现象。表明与其他亚型相比，A2—1和B2—1顺式NS3丝氨酸蛋白酶活性较弱。与其底物NS5A／SBAC共表达后，A2—1和B2-1亚型未切割NSSASB明显多于其他亚型，而切割NS5A则明显少于其他亚型。说明与其他亚型相比，A2—1和B2．1亚型的反式NS3蛋白酶活性亦较弱。荧光素酶试验结果显示，所有亚型M—H05-5／4A均显著抑制IFN-β启动子活性（P〈0．01）和p53依赖的荧光素酶基因的转录活性（P〈0．01），A2-1和B2-1亚型的抑制作用显著弱于其他亚型（P〈0．05）。结论氨基端不同二级结构的HCVNS3／4A复合体具有不同的丝氨酸酶活性和宿主细胞功能抑制作用。

Growth and optical properties of ytterbium and rare earth ions codoped CaF2-SrF2 eutectic solid-solution(RE=Y^(3+),Gd^(3+),La^(3+))

Ytterbium and rare earth ions(RE=Y,Gd,La)codoped CaF_(2)-SrF_(2)single crystals(3 at%Yb,6 at%RE:CaF_(2)-SrF_(2))were fabricated by temperature gradient technology(TGT).All the space groups remain the same Fm3m as that of Yb:CaF_(2)-SrF_(2).The lattice parameter a,unit cell volume V,as well as bond length of Ca/Sr-F and F-F increase in the sequence of rare-earth ions radius Y^(3+)<Gd^(3+)<La^(3+).The segregation coefficients of Yb ions are 0.87 in Yb,La:CaF_(2)-SrF_(2)and Yb,Gd:CaF_(2)-SrF_(2),which are larger than 0.85 in Yb,Y:CaF_(2)-SrF_(2)and 0.80 in Yb:CaF_(2)-SrF_(2).Absorption spectra in the range of 200 and 400 nm were analysed with Yb^(2+)contents.The absorption and emission cross-sections in the range of 900-1100 nm were determined together with fluorescence lifetime.The saturation pump density/Sat,minimum pump density/m in and gain cross-section were analysed.Yb,La:CaF_(2)-SrF_(2)has a relatively higher optical parameter(δem×t,0.52×10^(20)cm^(2)·ms),lower Isat(3.68 kW/cm^(2))and^min(0.50 kW/cm^(2))at 1038 nm indicating the potential application in high power laser.Low phonon energy of CaF_(2)-SrF_(2)is 302 cm^(-1)which is located between those of CaF_(2)and SrF_(2)as measured by Raman spectra.It is believed that ytterbium and rare earth ions(RE=Y^(3+),Cd^(3+),La^(3+))codoped CaF_(2)-SrF_(2)eutectic solid-solution is promising for high-power and wavelength-tunable solid-state lasers.

Analysis on electrical transport characteristic of 8-hydroquinoline aluminum film

The current_voltage and capacitance_voltage characteristic of the organic single_layered electroluminescent diode utilizing 8_hydroquinoline aluminum as active layer have been measured under bias ranging from -5 V to 28 V in this work. A simple model for charge transport process of 8_hydroquinoline aluminum layer is proposed to illuminate the conductivity characteristic of the diode.