This paper describes coherent optical orthogonal frequency division multiplexing (CO-OFDM) techniques for the long-haul transmission of 100-Gb/s-class channels. First, we discuss the configurations ...of the transmitter and receiver that implement the optical multiplexing/demultiplexing techniques for high-speed CO-OFDM transmission. Next, we review the no-guard-interval (No-GI) CO-OFDM transmission scheme which utilizes optical multiplexing for OFDM signal generation and the intradyne receiver configuration with digital signal processing (DSP). We examine the transmission characteristics of the proposed scheme, and show that No-GI CO-OFDM offers compact signal spectra and superior performance with regard to tolerance against optical amplifier noise and polarization-mode dispersion (PMD). We then introduce long-haul high-capacity transmission experiments employing No-GI CO-OFDM; 13.4 Tb/s (134 times 111 Gb/s) transmission is successfully demonstrated over 3600 km of ITU-T G.652 single-mode fiber without using optical dispersion compensation.
In
M
-estimation under standard asymptotics, the weak convergence combined with the polynomial type large deviation estimate of the associated statistical random field Yoshida (2011) provides us with ...not only the asymptotic distribution of the associated
M
-estimator but also the convergence of its moments, the latter playing an important role in theoretical statistics. In this paper, we study the above program for statistical random fields of multiple and also possibly mixedrates type in the sense of Radchenko (2008) where the associated statistical random fields may be nondifferentiable and may fail to be locally asymptotically quadratic. Consequently, a very strong mode of convergence of a wide range of regularized
M
-estimators is ensured.Our results are applied to regularized estimation of an ergodic diffusion observed at high frequency.
In residential areas, maintenance of power and communication lines is an important issue. In recent years, the frequency and power of typhoons and storms have significantly increased. If utility ...poles incline due to strong winds, slack cables may contact with large vehicles. For automatically detecting loose road-crossing cables in wide areas, the MMS is very promising. However, when roadcrossing cables are measured using the MMS, large portions of points on cables may be lost, because the directions of laser beams are nearly parallel to the directions of road-crossing cables, and therefore, the laser beams cross road-crossing cables only a small number of times. In this paper, we propose a new method for reconstructing cables crossing roads. In our method, road-crossing cables are reconstructed using both point clouds and camera images. While point clouds of road-crossing cables may be partly missing, their camera images can be captured with little occlusion. Missing portions are recovered using lines extracted from camera images. First, points of each cable are extracted from a point cloud, and the 3D vertical plane on which the cable exists are calculated. From camera images, 2D line segments are extracted as candidates of cable lines. 2D line segments are projected onto the 3D vertical plane using the pinhole camera model. Finally, 3D cable lines are reconstructed on the 3D vertical plane from the merged points. In our experiments, road-crossing cables could be sufficiently extracted using our method.
Efficient management of roadside trees for local governments is important. Mobile Mapping System (MMS) equipped with a high-density LiDAR scanner has the possibility to be applied to estimate DBH of ...roadside trees using point clouds. In this study, we propose a method for detecting roadside trees and estimating their DBHs automatically from MMS point clouds. In our method, point clouds captured using the MMS are mapped on a 2D image plane, and they are converted into a wireframe model by connecting adjacent points. Then, geometric features are calculated for each point in the wireframe model. Tree points are detected using a machine learning technique. The DBH of each tree is calculated using vertically aligned circles extracted from the wireframe model. Our method allows robustly calculating the DBH even if there is a hump at breast height. We evaluated our method using actual MMS data measured in an urban area in Tokyo. Our method achieved a high extraction performance of 100 percent of precision and 95.1 percent of recall for 102 roadside trees. The average accuracy of the DBH was 2.0 cm. These results indicate that our method is useful for the efficient management of roadside trees.
Stress–strain curves for ferrite-cementite (FC) steels with ferrite grain sizes between 0.47 and 13.6
μm were studied by tensile tests with strain rates of 10
3, 10
0, and 3.3
×
10
−4
s
−1 at 296
K. ...The stress–strain curves for the FC steels are categorized into two different types. In one type, the Lüders deformation is interrupted due to the onset of necking, and in the other type, the Lüders band propagates throughout the gage section of a tensile specimen followed by work-hardening. The lower yield and flow stresses increase while uniform and total elongations decrease with a decrease in ferrite grain size. The effect of ferrite grain size on flow stress is hardly dependent on strain rate. These experimental results reveal that the grain refinement strengthening contributes mainly to an increase in the athermal stress component.
TRAJECTORY-BASED VISUALIZATION OF MMS POINT CLOUDS Takahashi, G.; Masuda, H.
International archives of the photogrammetry, remote sensing and spatial information sciences.,
06/2019, Letnik:
XLII-2/W13
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
MMSs allow us to obtain detailed 3D information around roads. Especially, LiDAR point clouds can be used for map generation and infrastructure management. For practical uses, however, it is necessary ...to add labels to a part of the points since various objects can be included in the point clouds. Existing automatic classification methods are not completely error-free, and may incorrectly classify objects. Therefore, even though automatic methods are applied to the point clouds, operators have to verify the labels. While operators classify the point clouds manually, selecting 3D points tasks in 3D views are difficult. In this paper, we propose a new point-cloud image based on the trajectories of MMSs. We call our point-cloud image trajectory-based point-cloud image. Although the image is distorted because it is generated based on rotation angles of laser scanners, we confirmed that most objects can be recognized from point-cloud images by checking main road facilities. We evaluated how efficient the annotation can be done using our method, and the results show that operators could add annotations to point-cloud images more efficiently.
The mobile mapping system (MMS) can acquire dense point-clouds of roads and roadside features. Roads are often separated into roadways and walkways in many urban areas. Since guardrails are installed ...to separate roadways and sidewalks, it is important to detect guardrails from point-clouds and reconstruct their 3D models for 3D street maps. Since there are a large variety of designs for guardrails in Japan, flexible methods are required for detection and reconstruction of guardrails. In this paper, we propose a new method for extracting guardrails from point-clouds, and reconstructing their 3D models. Since the MMS captures point-clouds and camera images synchronously, guardrails are detected using both point-clouds and images. In our method, point-clouds are segmented into small segments, and corresponding images are cropped from camera images. Then cropped images are classified into two classes of guardrails and others using the convolutional neural network. When guardrail points are obtained, 3D models of guardrails are reconstructed. However, point-clouds of guardrails are too sparse to reconstruct 3D shapes when guardrails consist of thin pipes. Since the same unit shape repeatedly appears in a guardrail, we create dense point-clouds by superimposing points of unit shapes. Then we reconstruct 3D shapes of pipes, beams, and poles of guardrails. In our evaluation using point-clouds in urban areas, our method could achieve good results of extraction and shape reconstruction of guardrails.
Laser scanners on a vehicle-based mobile mapping system can capture 3D point-clouds of roads and roadside objects. Since roadside objects have to be maintained periodically, their 3D models are ...useful for planning maintenance tasks. In our previous work, we proposed a method for detecting cylindrical poles and planar plates in a point-cloud. However, it is often required to further classify pole-like objects into utility poles, streetlights, traffic signals and signs, which are managed by different organizations. In addition, our previous method may fail to extract low pole-like objects, which are often observed in urban residential areas. In this paper, we propose new methods for extracting and classifying pole-like objects. In our method, we robustly extract a wide variety of poles by converting point-clouds into wireframe models and calculating cross-sections between wireframe models and horizontal cutting planes. For classifying pole-like objects, we subdivide a pole-like object into five subsets by extracting poles and planes, and calculate feature values of each subset. Then we apply a supervised machine learning method using feature variables of subsets. In our experiments, our method could achieve excellent results for detection and classification of pole-like objects.
Stromal cell-derived factor-1 (SDF-1) is a chemokine considered to play an important role in the trafficking of hematopoietic stem cells. Given the close relationship between hematopoietic stem cells ...and endothelial progenitor cells (EPCs), we investigated the effect of SDF-1 on EPC-mediated vasculogenesis.
Flow cytometric analysis demonstrated expression of CXCR4, the receptor of SDF-1, by 66+/-3% of EPCs after 7 days in culture. In vitro modified Boyden chamber assay showed a dose-dependent EPC migration toward SDF-1 (control versus 10 ng/mL SDF-1 versus 100 ng/mL SDF-1, 24+/-2 versus 71+/-3 versus 140+/-6 cells/mm2; P<0.0001). SDF-1 attenuated EPC apoptosis (control versus SDF-1, 27+/-1 versus 7+/-1%; P<0.0001). To investigate the effect of SDF-1 in vivo, we locally injected SDF-1 into athymic ischemic hindlimb muscle of nude mice combined with human EPC transplantation to determine whether SDF-1 augmented EPC-induced vasculogenesis. Fluorescence microscopic examination disclosed increased local accumulation of fluorescence-labeled EPCs in ischemic muscle in the SDF-1 treatment group (control versus SDF-1=241+/-25 versus 445+/-24 cells/mm2, P<0.0001). At day 28 after treatment, ischemic tissue perfusion was improved in the SDF-1 group and capillary density was also increased. (control versus SDF-1, 355+/-26 versus 551+/-30 cells/mm2; P<0.0001).
These findings indicate that locally delivered SDF-1 augments vasculogenesis and subsequently contributes to ischemic neovascularization in vivo by augmenting EPC recruitment in ischemic tissues.
Background and purpose
Antinuclear antibody‐positive multiple sclerosis (MS) patients have shorter disease duration and lower Expanded Disability Status Scale (EDSS) scores. The aim of this study was ...to compare clinical and laboratory features between MS and neuromyelitis optica (NMO) patients with and without autoantibodies and to investigate the prognosis of NMO in patients with and without autoantibodies.
Methods
The frequencies of antinuclear, anti‐Sjögren's syndrome A (SSA)/Ro, anti‐Sjögren's syndrome B (SSB)/La and anti‐thyroid peroxidase (TPO) antibodies in the sera of 75 NMO patients and 131 MS patients were compared. Clinical and laboratory profiles were also compared between NMO patients with and without autoantibodies, including annual relapse rate and time from onset of NMO to EDSS scores of 4.0 (limited walking but without aid) and 6.0 (walking with unilateral aid).
Results
More NMO than MS patients had antinuclear and anti‐SSA/Ro antibodies (31% vs. 10%, P < 0.001, and 21% vs. 3%, P < 0.001, respectively). Antinuclear antibody‐positive NMO patients had a lower annual relapse rate from disease onset to serum sampling compared with antinuclear antibody‐negative NMO patients, independent of treatment regimen. Antinuclear antibody‐negative NMO patients reached an EDSS score of 6.0 earlier than antinuclear antibody‐positive NMO patients (P = 0.026). Cerebrospinal fluid cell counts were higher in anti‐SSA/Ro‐positive than in anti‐SSA/Ro‐negative NMO patients. More anti‐TPO antibody‐positive than anti‐TPO antibody‐negative NMO patients had oligoclonal immunoglobulin G bands (60% vs. 11%, P = 0.048).
Conclusions
Autoantibodies possibly modulate the pathophysiology of NMO. Antinuclear antibody may be associated with less severe disease activity or less disability in NMO.
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