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The traditional LiDAR simultaneous localization and mapping (SLAM) algorithm is subject to large outlier interference and inaccurate keyframe matching. To address this a LiDAR SLAM algorithm using normal distributions transform (NDT) matching combined with two-step screening of key frames is proposed. The algorithm is built on light weight and groundoptimized LiDAR odometry and mapping (LeGO-LOAM). First, the point cloud is pre-processed using statistical outlier removal (SOR). The current frame is matched with its corresponding key frame for NDT and the matching result is added to the loop closure detection. Feature extraction is performed on the keyframe and the feature points are added to the loop closure detection and pose map. A two-step keyframe screening method is used in the loop closure detection module to effectively reduce map building errors. The proposed method was evaluated on the Karlsruhe Institute of Technology and Toyota Technological Institute (KITTI) dataset. Additionally, the experimental results show that the proposed algorithm can improve the mapping accuracy as measured by the value of the root mean square error (RMSE). [ABSTRACT FROM AUTHOR]

Current LiDAR systems are limited to vertical field of view (FoV) have a blind scanning region which leads to uncompleted three-dimensional (3-D) spatial reconstruction. To solve this problem this paper proposes a device mounted with a multi-layer LiDAR to collect data, which spins clockwise around the LiDAR's y-axis. Statistical outlier removal (SOR) and an optimized voxel-grid filter are employed to do the point cloud registration. The coarse registration and the fine registration are performed by 3-D normal distributions transform (NDT) and point-to-plane iterative closest point (ICP), respectively. The completed 3-D reconstruction is unrestricted by the LiDAR's vertical FoV. Additionally, the experimental results show that the proposed algorithm can improve the registration accuracy as measured by the value of the root mean square error (RMSE). [ABSTRACT FROM AUTHOR]

G-C3N4 nanosheets were synthesized by hydrothermal method and then were anchored on the surface of mesoporous Co3O4 nanowires (NWs) to from g-C3N4/Co3O4 heterojunctions. After calcination, the influence of calcined temperature on the microstructures and gas-sensing performance is investigated in detail. All results show that g-C3N4 nanosheets affect the microstructure of Co3O4 NWs and are decorated on the surface of Co3O4 NWs. With the increasing calcination temperature, the specific surface area decreased from 64 m2/g for Co3O4 NWs to about 20 m2/g. The responses of g-C3N4/Co3O4 sensors are improved from 11.01 for Co3O4 sensor to about 20–100 ppm toluene gas, and CNC-500 presents excellent response values of 25.8 at the operating temperature of 220 °C. Although g-C3N4/Co3O4 heterojunctions exhibit the low specific surface area, the p-n heterojunctions at the interface of g-C3N4 and Co3O4 greatly increase the resistance in toluene gas. As the result, g-C3N4 nanosheets greatly improve the toluene gas-sensing performance of g-C3N4/Co3O4 sensors due to p-n heterojunctions. [ABSTRACT FROM AUTHOR]

Mesoporous SnO2, Sn0.861Al0.186O2, Sn0.921In0.106O2 and Sn0.959La0.055O2 nanospheres were successfully synthesized by a one-step solvothermal method. The compositions, crystal structures, microstructures, morphology and gas-sensing performance of the as-synthesized Al-, In- and La-doped SnO2 nanospheres were characterized by XRD, EDS, TEM, SEM, FT-IR, UV–vis and BET. All samples present the similar mesoporous-structural nanospheres due to the same chemical synthesis conditions. The gas-sensing results indicate that the cations-doping greatly affects the formaldehyde gas-sensing performance, and the response increases with the increasing radius of Al, In and La. Owing to the higher specific surface area and larger La3+ radius, Sn0.959La0.055O2 sensor presents the best gas-sensing performance with the response value of 149.59 to formaldehyde gas at 200 °C. It is concluded that metal-cation doping not only causes lattice distortion to increase oxygen vacancies, but also could refine the crystalline grain to improve the specific surface area of metal-cations doped SnO2 nanospheres. [ABSTRACT FROM AUTHOR]

We report a power efficient non-volatile magnetoelectric memory in the CoPt/(011)PMN-PT heterostructure. Two reversible and stable electric field induced coercivity states (i.e., high-HC or low-HC) are obtained due to the strain mediated converse magnetoelectric effect. The reading process of the different coercive field information written by electric fields is demonstrated by using a magnetoresistance read head. This result shows good prospects in the application of novel multiferroic devices. [ABSTRACT FROM AUTHOR]

High surface area nickel oxide nanowires (NiO NWs), Fe-doped NiO NWs and α-Fe2O3/Fe-doped NiO NWs were synthesized with nanocasting pathway, and then the morphology, microstructure and components of all samples were characterized with XRD, TEM, EDS, UV–vis spectra and nitrogen adsorption–desorption isotherms. Owing to the uniform mesoporous template, all samples with the same diameter exhibit the similar mesoporous-structures. The loaded α-Fe2O3 nanoparticles should exist in mesoporous channels between Fe-doped NiO NWs to form heterogeneous contact at the interface of n-type α-Fe2O3 nanoparticles and p-type NiO NWs. The gas-sensing results indicate that Fe-dopant and α-Fe2O3-loading both improve the gas-sensing performance of NiO NWs sensors. α-Fe2O3/Fe-doped NiO NWs sensors presented the highest response to 100 ppm ethanol gas (55.264) compared with Fe-doped NiO NWs (24.617) and NiO NWs sensors (3.189). The donor Fe-dopant increases the ground state resistance and the absorbed oxygen content in air. α-Fe2O3 nanoparticles in electron depletion region result in the increasing resistance in ethanol gas and decreasing resistance in air. In this way, α-Fe2O3/Fe-doped NiO NWs sensor presents the excellent gas-sensing performance due to the formation of heterogeneous contact at the interface. [ABSTRACT FROM AUTHOR]

Mesoporous n-type α-Fe2O3-decorated p-type NiO nanowires (NiO NWs) were synthesized via a two-step nanocasting method, and then the influence of the heterogeneous α-Fe2O3 decoration on the components, microstructure and gas-sensing performance of the NiO NWs was discussed in detail. All prepared samples with a uniform diameter present similar mesoporous microstructures. No α-Fe2O3 nanoparticles are observed on the surfaces of the NiO NWs and α-Fe2O3 nanoparticles are found to exist in the mesopores between nanowires. Decoration with α-Fe2O3 nanoparticles greatly affects the ethanol gas response. The response of the (Fe2O3)0.027NiO NW sensor is about 13 times that of a pristine NiO NW sensor toward 100 ppm ethanol gas at 280 °C. The (Fe2O3)0.027NiO NW sensor presents an excellent gas response, and good reproducibility and selectivity due to the α-Fe2O3 nanoparticles. The formation of α-Fe2O3/NiO p–n heterojunctions at the interfaces of the α-Fe2O3 nanoparticles and NiO NWs significantly affects electron transitions in air and ethanol gas. The small α-Fe2O3 nanoparticles (2–3.85 nm) are entirely within the electron depletion region in different gases due to the interfacial effects of p–n heterojunctions, leading to decreased resistance in air and increased resistance in ethanol gas. [ABSTRACT FROM AUTHOR]

We have studied, both experimentally and numerically, the radiometric efficiency of low-pressure barium–argon positive column discharges. Using a 14 mm inner diameter alumina discharge tube to reduce chemical reactivity, we have operated discharges with Ba vapor pressures corresponding to a range of oven temperatures from 600 to 800 °C, Ar buffer gas pressures of 0.5 and 5 Torr, and currents of 100–800 mA. The spectral power distribution has been determined by examining the visible radiation emitted perpendicular to the discharge axis from a small aperture in the side of the alumina discharge tube. Absolute emitted powers were determined by comparison to a calibrated tungsten–quartz–halogen lamp. The measured efficiencies for production of visible radiation from the positive column ranged from 2.5% to 52%. These efficiencies correspond to luminous efficacies ranging from 6 to 97 lm/W. Strong emission on Ba ion lines at 455.4, 493.4, 614.2, and 649.7 nm contributed significantly to the best efficiency, 52%, and yielded a white light. A numerical model, incorporating a substantial number of excited levels and atomic processes, has been used to examine the same conditions. The model reproduces most of the major experimental trends. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In order to improve the magnetic properties of MnBi compound, anisotropic MnBi/Sm2Fe17Nx hybrid magnet was prepared by grinding of high purity MnBi ribbons and Sm2Fe17Nx particles together. The smooth hysteresis loops of the hybrid magnets indicated that the mixture of the hard/hard phase magnetic components was well exchange coupled. As compared to the single MnBi phase magnet, the remanent magnetization and maximum energy product (BH)max of the composited magnets were improved. As an optimized result, the exchange coupled magnet of MnBi/Sm2Fe17Nx=3/7 yielded both high remanence and coercivity from 250K to 380 K. A maximum energy product (BH)max of 18 MGOe was achieved at 300 K, and remained 10 MGOe at 380 K, implying the MnBi/Sm2Fe17Nx magnets can be specially utilized in the high temperature environment. [ABSTRACT FROM AUTHOR]

This paper represents the first report of thermoplastic starch (scCO2TPS) and glutaraldehyde (GA) modified TPS resins (scCO2TPS100GAx), gelatinized and/or modified with the aid of supercritical carbon dioxide (scCO2). The melt flow rate, initial and retention values of tensile strength (σf) of TPS and GA-modified TPS prepared using scCO2 fluid were considerably higher than those of TPS and TPS100GAx materials prepared in the conventional way. After conditioning at 20 °C/50% RH for 56 days, the σf of properly prepared scCO2TPS100GA0.1 still remained at 17.5 MPa, which is around 3.5 times of that of the corresponding conditioned TPS100GA0.1. The moisture contents of conditioned scCO2TPS and scCO2TPS100GAx were considerably lower than those of the corresponding TPS and TPS100GAx aged for the same amounts of time. Conditioned scCO2TPS and scCO2TPS100GAx exhibited only Vh-type crystals with melting temperatures ~20°C lower than those of corresponding conditioned TPS and TPS100GAx. In comparison to TPS and TPS100GAx, more dissociated amylopectin chains with loosely hydrogen-bonded -OH groups and significantly less retrogradation was found for conditioned scCO2TPS and scCO2TPS100GAx. [ABSTRACT FROM AUTHOR]