Automated sparse 3D point cloud generation of infrastructure using its distinctive visual features

The commercial far-range (>10 m) spatial data collection methods for acquiring infrastructure’s geometric data are not completely automated because of the necessary manual pre- and/or post-processing work. The required amount of human intervention and, in some cases, the high equipment costs associated with these methods impede their adoption by the majority of infrastructure mapping activities. This paper presents an automated stereo vision-based method, as an alternative and inexpensive solution, to producing a sparse Euclidean 3D point cloud of an infrastructure scene utilizing two video streams captured by a set of two calibrated cameras. In this process SURF features are automatically detected and matched between each pair of stereo video frames. 3D coordinates of the matched feature points are then calculated via triangulation. The detected SURF features in two successive video frames are automatically matched and the RANSAC algorithm is used to discard mismatches. The quaternion motion estimation method is then used along with bundle adjustment optimization to register successive point clouds. The method was tested on a database of infrastructure stereo video streams. The validity and statistical significance of the results were evaluated by comparing the spatial distance of randomly selected feature points with their corresponding tape measurements.

重庆市主城区长江和嘉陵江水中有机污染物对斑马鱼胚胎仔鱼的毒性研究

目的以重庆市主城区大溪沟(嘉陵江)和寸滩(长江)两个点为代表,研究2004~2005年度重庆市水源水中有机污染物的组成和对斑马鱼胚胎仔鱼的毒性。方法固相萃取法萃取水中有机污染物,GC/MS检测有机污染物的种类;将萃取的有机污染物溶于DMSO中,并用斑马鱼胚胎仔鱼实验研究水中有机污染物对斑马鱼胚胎孵化率和仔鱼畸形率的影响。结果四个水样中均可检出有机污染物,污染物的种类以酞酸酯类和多环芳烃类为主;污染物可导致斑马鱼胚胎孵化率降低及仔鱼畸形率增加,其毒性呈现出时间和剂量依赖性;同一采样点中,枯水期水样毒性大于丰

复合垂直流人工湿地污水氮的去除效果研究

采用复合垂直流人工湿地(IVCW)系统,研究了系统内部水流方向上各态氮和其它理化参数的变化。结果表明,复合垂直流人工湿地中,硝态氮、亚硝态氮、溶解氧和pH沿水流方向逐渐减小;总氮去除率为43.63%,可使劣Ⅴ类水的总氮指标降至Ⅲ类;氮的去除主要发生在下行池,上行池因溶解氧低、有机碳不足和系统向水中释放氮的原因,脱氮效果不明显。

Video segmentation with superpixels

Due to its importance, video segmentation has regained interest recently. However, there is no common agreement about the necessary ingredients for best performance. This work contributes a thorough analysis of various within- and between-frame affinities suitable for video segmentation. Our results show that a frame-based superpixel segmentation combined with a few motion and appearance-based affinities are sufficient to obtain good video segmentation performance. A second contribution of the paper is the extension of [1] to include motion-cues, which makes the algorithm globally aware of motion, thus improving its performance for video sequences. Finally, we contribute an extension of an established image segmentation benchmark [1] to videos, allowing coarse-to-fine video segmentations and multiple human annotations. Our results are tested on BMDS [2], and compared to existing methods. © 2013 Springer-Verlag.

Investigating landing gear noise using fly-over data: The case of a Boeing 747-400

Modeling the noise originating from a landing gear has proven to be a challenging task, because of its complicated structure. In full-scale, landing gear noise can only be investigated experimentally by source localization techniques and fly-over measurements with microphone arrays. In the present work, measurements of a Boeing B747-400 were used to determine the contribution of the landing gear to the overall noise emitted during a fly-over and how the broadband noise from the landing gear scales with the flight velocity. A tonal source from the nose landing gear was identified at 380 Hz with a harmonic at 760 Hz and it most likely originates from a cavity. It was also found that the Power Spectral Density (PSD) of the high frequency broadband component varies linearly with frequency and there is some scaling with the ow velocity. Finally, the nose landing gear was shown to be a significant contributor to the overall airframe noise as expected.

Determinations of MC-LR and [Dha(7)] MC-LR Concentrations and Physicochemical Properties by Liquid Chromatography-Tandem Mass Spectrometry

A liquid chromatography electrospray mass spectrometry (LC/ESI/MS) method working in multiple reactions monitoring mode for the determination of trace amounts of microcystin variants (MC-LR and [Dha(7)] MC-LR) in waters was developed. The limit of quantification was 0.05 mu g/L and the limit of detection was 0.015 mu g/L for MC-LR and [Dha(7)] MC-LR, respectively. Recoveries for MCs were in the range of 68%-81%. MC-LR and [Dha(7)] MC-LR were chemically stable with similar physiochemical behavior.

Nitrate and phosphate supplementation to increase toxin production by the marine dinoflagellate Alexandrium tamarense

Alexandrium tamarense toxins have great value in biotechnology research as well as important in connection with shellfish poisoning. The influence of nitrate or nitrate and phosphate supplementation on cell biomass and toxin content were investigated in batch cultures. When cultures at low nitrate (88.2 mu M NaNO3) Were supplemented with 793.8 mu M NaNO3 at day 10 the cell density and cellular toxin contents were increased by 6-29% and 20-76%, respectively, compared with controls, and maximal values were 43,600 cells/ml (day 38) and 0.91 pg/cell (day 31). Supplementation with nitrate at day 14 or with nitrate and phosphate at day 10/14 to the cultures did not increase the cell density compared with the non-supplemented middle nitrate or high phosphate (108 mu M NaH2PO4) cultures, respectively, but increased the cellular toxin contents by an average of 52%. The results showed that supplementation with nitrate or with nitrate and phosphate at different growth phases of the cultures increased toxin yield by an average of 46%. Supplementation with nitrate at selected times to maintain continuous low level of nitrate might contribute to the effective increase of toxin yield of A. tamarense. (c) 2005 Elsevier Ltd. All rights reserved.

Sub-nanosecond silicon-on-insulator optical micro-ring switch with low crosstalk

We demonstrate a sub-nanosecond electro-optical switch with low crosstalk in a silicon-on-insulator (SOI) dual-coupled micro-ring embedded with p-i-n diodes. A crosstalk of -23 dB is obtained in the 20-mu m-radius micro-ring with the well-designing asymmetric dual-coupling structure. By optimizations of the doping profiles and the fabrication processes, the sub-nanosecond switch-on/off time of < 400 ps is finally realized under an electrical pre-emphasized driving signal. This compact and fast-response micro-ring switch, which can be fabricated by complementary metal oxide semiconductor (CMOS) compatible technologies, have enormous potential in optical interconnects of multicore networks-on-chip.

Quantum phase transitions in the S=1/2 distorted diamond chain

By means of the second derivative of the ground-state and first-excited energy, the quantum phase transitions (QPTs) for the distorted diamond chain (DDC) with ferromagnetic and antiferromagnetic frustrated interactions and the trimerized case are investigated, respectively. Our results show the plentiful quantum phases owing to the spin interaction competitions in the model. Meanwhile, by using the transfer-matrix renormalization-group technique, we study the two-site thermal entanglement of the DDC model in the thermodynamic limit for a further understanding of the QPTs.

Silicon light emitting devices in CMOS technology

Two silicon light emitting devices with different structures are realized in standard 0.35 mu m complementary metal-oxide-semiconductor (CMOS) technology. They operate in reverse breakdown mode and can be turned on at 8.3 V. Output optical powers of 13.6 nW and 12.1 nW are measured at 10 V and 100 mA, respectively, and both the calculated light emission intensities are more than 1 mW/Cm-2. The optical spectra of the two devices are between 600-790 nm with a clear peak near 760 nm..

Capacitance-voltage spectroscopy of In0.5Ga0.5As self-assembled quantum dots in double quantum wells under selective photo-excitation

Selectively photo-excited C-V spectroscopy has been measured in an In0.5Ga0.5As quantum dots (QDs)-embedded, three barrier-two well heterostructure. By comparing with a theoretical capacitance model, the pure capacitive contribution from In0.5Ga0.5As QDs, due to tunnelling coupling between In0.5Ga0.5As QDs and In0.18Ga0.82As quantum well, has been used to obtain the density of charges from photo-excited In0.5Ga0.5As QDs in a very straightforward manner.