Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 70
Filtrar
Más filtros

Bases de datos
Tipo del documento
Intervalo de año de publicación
1.
J Cell Sci ; 134(3)2021 02 05.
Artículo en Inglés | MEDLINE | ID: mdl-33443093

RESUMEN

Expression of synphilin-1 in neurons induces hyperphagia and obesity in a Drosophila model. However, the molecular pathways underlying synphilin-1-linked obesity remain unclear. Here, Drosophila models and genetic tools were used to study the synphilin-1-linked pathways in energy balance by combining molecular biology and pharmacological approaches. We found that expression of human synphilin-1 in flies increased AMP-activated kinase (AMPK) phosphorylation at Thr172 compared with that in non-transgenic flies. Knockdown of AMPK reduced AMPK phosphorylation and food intake in non-transgenic flies, and further suppressed synphilin-1-induced AMPK phosphorylation, hyperphagia, fat storage and body weight gain in transgenic flies. Expression of constitutively activated AMPK significantly increased food intake and body weight gain in non-transgenic flies, but it did not alter food intake in the synphilin-1 transgenic flies. In contrast, expression of dominant-negative AMPK reduced food intake in both non-transgenic and synphilin-1 transgenic flies. Treatment with STO-609 also suppressed synphilin-1-induced AMPK phosphorylation, hyperphagia and body weight gain. These results demonstrate that the AMPK signaling pathway plays a critical role in synphilin-1-induced hyperphagia and obesity. These findings provide new insights into the mechanisms of synphilin-1-controlled energy homeostasis.


Asunto(s)
Proteínas Quinasas Activadas por AMP , Proteínas Portadoras/genética , Drosophila , Hiperfagia , Proteínas del Tejido Nervioso/genética , Obesidad , Proteínas Quinasas Activadas por AMP/genética , Proteínas Quinasas Activadas por AMP/metabolismo , Animales , Animales Modificados Genéticamente , Drosophila/genética , Drosophila/metabolismo , Humanos , Hiperfagia/genética , Obesidad/genética , Transducción de Señal/genética
2.
Anticancer Drugs ; 34(1): 15-28, 2023 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-36206143

RESUMEN

Chordoma is a rare malignant bone tumor originating from the remnants of the notochord. Here, the role of long noncoding LOC554202 in chordoma progression and its associated mechanism were explored. Cell proliferation was analyzed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazolium bromide and colony formation assays. Flow cytometry was conducted to analyze cell apoptosis rate. The migration and invasion of chordoma cells were analyzed by transwell migration and invasion assays and wound healing assays. A xenograft tumor model was established in nude mice to explore the role of LOC554202 in regulating tumor growth in vivo . The interaction between microRNA-377-3p (miR-377-3p) and LOC554202 or sekelsky mothers against d PP (SMAD) family member 3 (SMAD3) was verified by dual-luciferase reporter and RNA immunoprecipitation assays. The glycolytic rate of chordoma cells was analyzed using glucose assay kit, lactic acid kit and ApoSENSOR ADP/ATP ratio assay kit. LOC554202 expression was upregulated in chordoma tissues and cell lines. LOC554202 silencing suppressed the proliferation, migration and invasion and induced the apoptosis of chordoma cells. LOC554202 knockdown restrained xenograft tumor growth in vivo . miR-377-3p was confirmed as a target of LOC554202, and miR-377-3p silencing largely overturned LOC554202 knockdown-mediated anti-tumor effects in chordoma cells. miR-377-3p interacted with the 3' untranslated region (3'UTR) of SMAD3 and miR-377-3p overexpression-mediated antitumor effects in chordoma cells were largely attenuated by SMAD3 overexpression. LOC554202 could positively regulate SMAD3 expression by sponging miR-377-3p in chordoma cells. LOC554202 contributed to the glycolysis of chordoma cells by targeting binding to miR-377-3p/SMAD3 axis. LOC554202 facilitated the proliferation, migration, invasion and glycolysis and inhibited the apoptosis of chordoma cells by mediating miR-377-3p/SMAD3 axis.


Asunto(s)
Cordoma , MicroARNs , Animales , Humanos , Ratones , Línea Celular Tumoral , Movimiento Celular , Proliferación Celular/genética , Cordoma/genética , Modelos Animales de Enfermedad , Regulación Neoplásica de la Expresión Génica , Ratones Desnudos , MicroARNs/genética , MicroARNs/metabolismo , Proteína smad3/genética , Proteína smad3/metabolismo , ARN Largo no Codificante/genética
3.
Exp Cell Res ; 416(1): 113155, 2022 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-35427600

RESUMEN

CTP synthase (CTPS), the enzyme responsible for the last step of de novo synthesis of CTP, forms filamentous structures termed cytoophidia in all three domains of life. Here we report that oncogenic Ras regulates cytoophidium formation in Drosophila intestines. Overexpressing active Ras induces elongate and abundant cytoophidia in intestinal stem cells (ISCs) and enteroblasts (EBs). Knocking-down CTPS in ISCs/EBs suppresses the over- proliferation phenotype induced by ectopic expression of active Ras. Moreover, disrupting cytoophidium formation increases the number of proliferating cells in the background of overexpressing active Ras. Therefore, our results demonstrate a link between Ras and CTPS.


Asunto(s)
Ligasas de Carbono-Nitrógeno , Drosophila , Animales , Ligasas de Carbono-Nitrógeno/genética , Intestinos , Células Madre
4.
Cell Mol Life Sci ; 79(10): 534, 2022 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-36180607

RESUMEN

Tissue architecture determines its unique physiology and function. How these properties are intertwined has remained unclear. Here we show that the metabolic enzyme CTP synthase (CTPS) form filamentous structures termed cytoophidia along the adipocyte cortex in Drosophila adipose tissue. Loss of cytoophidia, whether due to reduced CTPS expression or a point mutation that specifically abrogates its polymerization ability, causes impaired adipocyte adhesion and defective adipose tissue architecture. Moreover, CTPS influences integrin distribution and dot-like deposition of type IV collagen (Col IV). Col IV-integrin signaling reciprocally regulates the assembly of cytoophidia in adipocytes. Our results demonstrate that a positive feedback signaling loop containing both cytoophidia and integrin adhesion complex couple tissue architecture and metabolism in Drosophila adipose tissue.


Asunto(s)
Ligasas de Carbono-Nitrógeno , Colágeno Tipo IV , Animales , Tejido Adiposo/metabolismo , Ligasas de Carbono-Nitrógeno/química , Ligasas de Carbono-Nitrógeno/genética , Ligasas de Carbono-Nitrógeno/metabolismo , Drosophila/metabolismo , Integrinas
5.
Opt Express ; 30(10): 17278-17289, 2022 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-36221554

RESUMEN

We present a method to reconstruct the near-water-film air temperature and humidity distributions synchronously by measuring the phase delays based on dual-wavelength digital holographic interferometry. A falling water film device was used to create a water film evaporation environment and generate axially uniform temperature and humidity fields. The relationship between air temperature, humidity and phase delay is derived from the Edlen equations. With such relationship, the temperature and humidity distributions can be solved directly according to phase delays of two different wavelengths. An edge phase enhancement method and an error elimination method with PSO are presented to improve the measurement accuracy. The temperature and humidity fields in the falling water film model were experimentally reconstructed with temperature deviation of 0.06% and relative humidity deviation of 2.61%.

6.
Exp Cell Res ; 408(1): 112838, 2021 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-34560103

RESUMEN

CTP synthase (CTPS) senses all four nucleotides and forms filamentous structures termed cytoophidia in all three domains of life. How CTPS and cytoophidia function in a developmental context, however, remains underexplored. We report that CTPS forms cytoophidia in a subset of cells in the Drosophila midgut. We found that cytoophidia exist in intestinal stem cells (ISC) and enteroblasts in similar proportions. Both refeeding after starvation and feeding with dextran sulfate sodium (DSS) induce ISC proliferation and elongate cytoophidia. Knockdown of CTPS inhibits ISC proliferation. Remarkably, disruption of CTPS cytoophidia inhibits DSS-induced ISC proliferation. Taken together, these data suggest that both the expression level and the filament-form property of CTPS are crucial for intestinal homeostasis in Drosophila.


Asunto(s)
Ligasas de Carbono-Nitrógeno/metabolismo , Sulfato de Dextran/farmacología , Homeostasis/efectos de los fármacos , Células Madre/efectos de los fármacos , Animales , Ligasas de Carbono-Nitrógeno/efectos de los fármacos , Citoesqueleto/efectos de los fármacos , Citoesqueleto/metabolismo , Drosophila , Homeostasis/fisiología , Intestinos/citología , Intestinos/efectos de los fármacos , Células Madre/citología
7.
Neoplasma ; 69(1): 1-15, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34704451

RESUMEN

Papillary thyroid carcinoma (PTC) is the most prevalent form of thyroid cancer (TC). There is increasing evidence that circular RNAs play a role in the tumorigenesis of PTC. The aim of our study was to evaluate the potential function of circ_0067934 in PTC and the underlying molecular mechanism. In our study, cell viability assay, quantitative real-time PCR (qRT-PCR), colony formation assay, flow cytometry, wound-healing assay, Transwell invasion assay, western blot, soft agar assay, RNA immunoprecipitation (RIP), dual-luciferase reporter assay, immunohistochemical (IHC) staining, and tumor xenograft formation were conducted to evaluate the effects of circ_0067934 in PTC cells. We found that circ_0067934 was upregulated in PTC tissues and cell lines. Knockdown of circ_0067934 inhibited growth, colony formation, migration, invasion, EMT, and tumor xenograft growth, and induced apoptosis of PTC cells. Moreover, circ_0067934 acted as a molecular sponge for miR-1301-3p, and depletion of miR-1301-3p abrogated the effects of circ_0067934 knockdown in PTC cells. In addition, HMGB1 was a target of miR-1301-3p, and miR-1301-3p overexpression inhibited the malignant effects of PTC cells via suppressing HMGB1. Furthermore, knockdown of circ_0067934 suppressed HMGB1 expression, PI3K/Akt, and MAPK activation by sponging miR-1301-3p. In nude mice, circ_0067934 depletion repressed tumor xenograft growth of PTC cells. In conclusion, our results provided a novel insight into circ_0067934 in the tumorigenesis and progression of PTC. circ_0067934 might be a prognostic marker or therapeutic target for PTC treatment.


Asunto(s)
Proteína HMGB1 , MicroARNs , ARN Circular/genética , Neoplasias de la Tiroides , Animales , Línea Celular Tumoral , Proliferación Celular , Proteína HMGB1/genética , Humanos , Ratones , Ratones Desnudos , MicroARNs/genética , Fosfatidilinositol 3-Quinasas , Cáncer Papilar Tiroideo/genética , Neoplasias de la Tiroides/genética
8.
Entropy (Basel) ; 24(4)2022 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-35455117

RESUMEN

In this paper, four stabilized methods based on the lowest equal-order finite element pair for the steady micropolar Navier-Stokes equations (MNSE) are presented, which are penalty, regular, multiscale enrichment, and local Gauss integration methods. A priori properties, existence, uniqueness, stability, and error estimation based on Fem approximation of all the methods are proven for the physical variables. Finally, some numerical examples are displayed to show the numerical characteristics of these methods.

9.
Sensors (Basel) ; 21(7)2021 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-33918443

RESUMEN

Continuous maintenance and real-time update of high-definition (HD) maps is a big challenge. With the development of autonomous driving, more and more vehicles are equipped with a variety of advanced sensors and a powerful computing platform. Based on mid-to-high-end sensors including an industry camera, a high-end Global Navigation Satellite System (GNSS)/Inertial Measurement Unit (IMU), and an onboard computing platform, a real-time HD map change detection method for crowdsourcing update is proposed in this paper. First, a mature commercial integrated navigation product is directly used to achieve a self-positioning accuracy of 20 cm on average. Second, an improved network based on BiSeNet is utilized for real-time semantic segmentation. It achieves the result of 83.9% IOU (Intersection over Union) on Nvidia Pegasus at 31 FPS. Third, a visual Simultaneous Localization and Mapping (SLAM) associated with pixel type information is performed to obtain the semantic point cloud data of features such as lane dividers, road markings, and other static objects. Finally, the semantic point cloud data is vectorized after denoising and clustering, and the results are matched with a pre-constructed HD map to confirm map elements that have not changed and generate new elements when appearing. The experiment conducted in Beijing shows that the method proposed is effective for crowdsourcing update of HD maps.

10.
Sensors (Basel) ; 20(24)2020 Dec 13.
Artículo en Inglés | MEDLINE | ID: mdl-33322184

RESUMEN

Vision-based sensors such as LiDAR (Light Detection and Ranging) are adopted in the SLAM (Simultaneous Localization and Mapping) system. In the 16-beam LiDAR aided SLAM system, due to the difficulty of object detection by sparse laser data, neither the grid-based nor feature point-based solution can avoid the interference of moving objects. In an urban environment, the pole-like objects are common, invariant and have distinguishing characteristics. Therefore, it is suitable to bring more robust and reliable positioning results as auxiliary information in the process of vehicle positioning and navigation. In this work, we proposed a scheme of a SLAM system using a GNSS (Global Navigation Satellite System), IMU (Inertial Measurement Unit) and LiDAR sensor using the position of pole-like objects as the features for SLAM. The scheme combines a traditional preprocessing method and a small scale artificial neural network to extract the pole-like objects in environment. Firstly, the threshold-based method is used to extract the pole-like object candidates from the point cloud, and then, the neural network is applied for training and inference to obtain pole-like objects. The result shows that the accuracy and recall rate are sufficient to provide stable observation for the following SLAM process. After extracting the poles from the LiDAR point cloud, their coordinates are added to the feature map, and the nonlinear optimization of the front end is carried out by utilizing the distance constraints corresponding to the pole coordinates; then, the heading angle and horizontal plane translation are estimated. The ground feature points are used to enhance the elevation, pitch and roll angle accuracy. The performance of the proposed navigation system is evaluated through field experiments by checking the position drift and attitude errors during multiple two-min mimic GNSS outages without additional IMU motion constrain such as NHC (Nonholonomic Constrain). The experimental results show that the performance of the proposed scheme is superior to that of the conventional feature point grid-based SLAM with the same back end, especially in congested crossroads where slow-moving vehicles are surrounded and pole-like objects are rich in the environment. The mean plane position error during two-min GNSS outages was reduced by 38.5%, and the root mean square error was reduced by 35.3%. Therefore, the proposed pole-like feature-based GNSS/IMU/LiDAR SLAM system can fuse condensed information from those sensors effectively to mitigate positioning and orientation errors, even in a short-time GNSS denied environment.

11.
Int J Mol Sci ; 21(12)2020 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-32570982

RESUMEN

A role for the cytoplasmic protein synphilin-1 in regulating energy balance has been demonstrated recently. Expression of synphilin-1 increases ATP levels in cultured cells. However, the mechanism by which synphilin-1 alters cellular energy status is unknown. Here, we used cell models and biochemical approaches to investigate the cellular functions of synphilin-1 on the AMP-activated protein kinase (AMPK) signaling pathway, which may affect energy balance. Overexpression of synphilin-1 increased AMPK phosphorylation (activation). Moreover, synphilin-1 interacted with AMPK by co-immunoprecipitation and GST (glutathione S-transferase) pull-down assays. Knockdown of synphilin-1 reduced AMPK phosphorylation. Overexpression of synphilin-1 also altered AMPK downstream signaling, i.e., a decrease in acetyl CoA carboxylase (ACC) phosphorylation, and an increase in p70S6K phosphorylation. Treatment of compound C (an AMPK inhibitor) reduced synphilin-1 binding with AMPK. In addition, compound C diminished synphilin-1-induced AMPK phosphorylation, and the increase in cellular ATP (adenosine triphosphate) levels. Our results demonstrated that synphilin-1 couples with AMPK, and they exert mutual effects on each other to regulate cellular energy status. These findings not only identify novel cellular actions of synphilin-1, but also provide new insights into the roles of synphilin-1 in regulating energy currency, ATP.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Adenosina Trifosfato/metabolismo , Proteínas Portadoras/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Acetil-CoA Carboxilasa/metabolismo , Células HEK293 , Humanos , Fosforilación , Unión Proteica , Pirazoles/farmacología , Pirimidinas/farmacología , Transducción de Señal/efectos de los fármacos
12.
Entropy (Basel) ; 22(9)2020 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-33286750

RESUMEN

Rényi entropy as a generalization of the Shannon entropy allows for different averaging of probabilities of a control parameter α. This paper gives a new perspective of the Kalman filter from the Rényi entropy. Firstly, the Rényi entropy is employed to measure the uncertainty of the multivariate Gaussian probability density function. Then, we calculate the temporal derivative of the Rényi entropy of the Kalman filter's mean square error matrix, which will be minimized to obtain the Kalman filter's gain. Moreover, the continuous Kalman filter approaches a steady state when the temporal derivative of the Rényi entropy is equal to zero, which means that the Rényi entropy will keep stable. As the temporal derivative of the Rényi entropy is independent of parameter α and is the same as the temporal derivative of the Shannon entropy, the result is the same as for Shannon entropy. Finally, an example of an experiment of falling body tracking by radar using an unscented Kalman filter (UKF) in noisy conditions and a loosely coupled navigation experiment are performed to demonstrate the effectiveness of the conclusion.

13.
Sensors (Basel) ; 19(15)2019 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-31382700

RESUMEN

The fusion of visual and inertial measurements for motion tracking has become prevalent in the robotic community, due to its complementary sensing characteristics, low cost, and small space requirements. This fusion task is known as the vision-aided inertial navigation system problem. We present a novel hybrid sliding window optimizer to achieve information fusion for a tightly-coupled vision-aided inertial navigation system. It possesses the advantages of both the conditioning-based method and the prior-based method. A novel distributed marginalization method was also designed based on the multi-state constraints method with significant efficiency improvement over the traditional method. The performance of the proposed algorithm was evaluated with the publicly available EuRoC datasets and showed competitive results compared with existing algorithms.

14.
Sensors (Basel) ; 19(1)2019 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-30621112

RESUMEN

Currently, the Global Navigation Satellite System (GNSS) mainly uses the satellites in Medium Earth Orbit (MEO) to provide position, navigation, and timing (PNT) service. The weak navigation signals limit its usage in deep attenuation environments, and make it easy to interference and counterfeit by jammers or spoofers. Moreover, being far away to the Earth results in relatively slow motion of the satellites in the sky and geometric change, making long time needed for achieved centimeter positioning accuracy. By using the satellites in Lower Earth Orbit (LEO) as the navigation satellites, these disadvantages can be addressed. In this contribution, the advantages of navigation from LEO constellation has been investigated and analyzed theoretically. The space segment of global Chinese BeiDou Navigation Satellite System consisting of three GEO, three IGSO, and 24 MEO satellites has been simulated with a LEO constellation with 120 satellites in 10 orbit planes with inclination of 55 degrees in a nearly circular orbit (eccentricity about 0.000001) at an approximate altitude of 975 km. With simulated data, the performance of LEO constellation to augment the global Chinese BeiDou Navigation Satellite System (BeiDou-3) has been assessed, as one of the example to show the promising of using LEO as navigation system. The results demonstrate that the satellite visibility and position dilution of precision have been significantly improved, particularly in mid-latitude region of Asia-Pacific region, once the LEO data were combined with BeiDou-3 for navigation. Most importantly, the convergence time for Precise Point Positioning (PPP) can be shorted from about 30 min to 1 min, which is essential and promising for real-time PPP application. Considering there are a plenty of commercial LEO communication constellation with hundreds or thousands of satellites, navigation from LEO will be an economic and promising way to change the heavily relay on GNSS systems.

15.
Hum Mol Genet ; 25(4): 672-80, 2016 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-26744328

RESUMEN

Mutations in leucine-rich repeat kinase 2 (LRRK2) cause autosomal-dominant Parkinsonism with pleomorphic pathology including deposits of aggregated protein and neuronal degeneration. The pathogenesis of LRRK2-linked Parkinson's disease (PD) is not fully understood. Here, using co-immunoprecipitation, we found that LRRK2 interacted with synphilin-1 (SP1), a cytoplasmic protein that interacts with α-synuclein and has implications in PD pathogenesis. LRRK2 interacted with the N-terminus of SP1 whereas SP1 predominantly interacted with the C-terminus of LRRK2, including kinase domain. Co-expression of SP1 with LRRK2 increased LRRK2-induced cytoplasmic aggregation in cultured cells. Moreover, SP1 also attenuated mutant LRRK2-induced toxicity and reduced LRRK2 kinase activity in cultured cells. Knockdown of SP1 by siRNA enhanced LRRK2 neuronal toxicity. In vivo Drosophila studies, co-expression of SP1 and mutant G2019S-LRRK2 in double transgenic Drosophila increased survival and improved locomotor activity. Expression of SP1 protects against G2019S-LRRK2-induced dopamine neuron loss and reduced LRRK2 phosphorylation in double transgenic fly brains. Our findings demonstrate that SP1 attenuates mutant LRRK2-induced PD-like phenotypes and plays a neural protective role.


Asunto(s)
Proteínas Portadoras/metabolismo , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Enfermedad de Parkinson/metabolismo , Animales , Animales Modificados Genéticamente , Proteínas Portadoras/genética , Línea Celular Tumoral , Modelos Animales de Enfermedad , Dopamina/metabolismo , Drosophila , Técnicas de Silenciamiento del Gen , Células HEK293 , Humanos , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina/genética , Ratones , Mutación , Degeneración Nerviosa/genética , Proteínas del Tejido Nervioso/genética , Neuronas/enzimología , Neuronas/metabolismo , Neuronas/patología , Enfermedad de Parkinson/enzimología , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/patología , Fosforilación , Dominios y Motivos de Interacción de Proteínas , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismo
16.
Sensors (Basel) ; 18(1)2018 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-29320406

RESUMEN

Car ownership in China reached 194 million vehicles at the end of 2016. The traffic congestion index (TCI) exceeds 2.0 during rush hour in some cities. Inefficient processing for minor traffic accidents is considered to be one of the leading causes for road traffic jams. Meanwhile, the process after an accident is quite troublesome. The main reason is that it is almost always impossible to get the complete chain of evidence when the accident happens. Accordingly, a police and insurance joint management system is developed which is based on high precision BeiDou Navigation Satellite System (BDS)/Global Positioning System (GPS) positioning to process traffic accidents. First of all, an intelligent vehicle rearview mirror terminal is developed. The terminal applies a commonly used consumer electronic device with single frequency navigation. Based on the high precision BDS/GPS positioning algorithm, its accuracy can reach sub-meter level in the urban areas. More specifically, a kernel driver is built to realize the high precision positioning algorithm in an Android HAL layer. Thus the third-party application developers can call the general location Application Programming Interface (API) of the original standard Global Navigation Satellite System (GNSS) to get high precision positioning results. Therefore, the terminal can provide lane level positioning service for car users. Next, a remote traffic accident processing platform is built to provide big data analysis and management. According to the big data analysis of information collected by BDS high precision intelligent sense service, vehicle behaviors can be obtained. The platform can also automatically match and screen the data that uploads after an accident to achieve accurate reproduction of the scene. Thus, it helps traffic police and insurance personnel to complete remote responsibility identification and survey for the accident. Thirdly, a rapid processing flow is established in this article to meet the requirements to quickly handle traffic accidents. The traffic police can remotely identify accident responsibility and the insurance personnel can remotely survey an accident. Moreover, the police and insurance joint management system has been carried out in Wuhan, Central China's Hubei Province, and Wuxi, Eastern China's Jiangsu Province. In a word, a system is developed to obtain and analyze multisource data including precise positioning and visual information, and a solution is proposed for efficient processing of traffic accidents.

17.
Sensors (Basel) ; 18(1)2018 Jan 05.
Artículo en Inglés | MEDLINE | ID: mdl-29304000

RESUMEN

In 2015, the plan for global coverage by the Chinese BeiDou Navigation Satellite System was launched. Five global BeiDou experimental satellites (BeiDou-3e) are in orbit for testing. To analyze the performances of precise orbit determination (POD) and precise point positioning (PPP) of onboard BeiDou satellites, about two months of data from 24 tracking stations were used. According to quality analysis of BeiDou-2/BeiDou-3e data, there is no satellite-induced code bias in BeiDou-3e satellites, which has been found in BeiDou-2 satellites. This phenomenon indicates that the quality issues of pseudorange data in BeiDou satellites have been solved well. POD results indicate that the BeiDou-3e orbit precision is comparable to that of BeiDou-2 satellites. The ambiguity fixed solution improved the orbit consistency of inclined geosynchronous orbit satellites in along-track and cross-track directions, but had little effect in the radial direction. Satellite laser ranging of BeiDou-3e medium Earth orbit satellites (MEOs) achieved a standard deviation of about 4 cm. Differences in clock offset series after the removal of reference clock in overlapping arcs were used to assess clock quality, and standard deviation of clock offset could reach 0.18 ns on average, which was in agreement with the orbit precision. For static PPP, when BeiDou-3e satellites were included, the positioning performance for horizontal components was improved slightly. For kinematic PPP, when global positioning satellites (GPS) were combined with BeiDou-2 and BeiDou-3e satellites, the convergence time was 13.5 min with a precision of 2-3 cm for horizontal components, and 3-4 cm for the vertical component.

18.
Sensors (Basel) ; 18(2)2018 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-29439423

RESUMEN

Accurate measurement of the railway track geometry is a task of fundamental importance to ensure the track quality in both the construction phase and the regular maintenance stage. Conventional track geometry measuring trolleys (TGMTs) in combination with classical geodetic surveying apparatus such as total stations alone cannot meet the requirements of measurement accuracy and surveying efficiency at the same time. Accurate and fast track geometry surveying applications call for an innovative surveying method that can measure all or most of the track geometric parameters in short time without interrupting the railway traffic. We provide a novel solution to this problem by integrating an inertial navigation system (INS) with a geodetic surveying apparatus, and design a modular TGMT system based on aided INS, which can be configured according to different surveying tasks including precise adjustment of slab track, providing tamping measurements, measuring track deformation and irregularities, and determination of the track axis. TGMT based on aided INS can operate in mobile surveying mode to significantly improve the surveying efficiency. Key points in the design of the TGMT's architecture and the data processing concept and workflow are introduced in details, which should benefit subsequent research and provide a reference for the implementation of this kind of TGMT. The surveying performance of proposed TGMT with different configurations is assessed in the track geometry surveying experiments and actual projects.

19.
Sensors (Basel) ; 17(6)2017 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-28555027

RESUMEN

Since 2015, China has successfully launched five experimental BeiDou global navigation system (BDS-3) satellites for expanding the regional system to global coverage. An initial performance assessment and characterization analysis of the BDS-3 is presented. Twenty days of tracking data have been collected from eleven monitoring stations. The tracking characteristics and measurement quality are analyzed and compared with the regional BDS (BDS-2) in terms of observed carrier-to-noise density ratio, pseudo-range multipath, and noise. The preliminary results suggest that the measurement quality of BDS-3 outperforms the BDS-2 for the same type of satellites. In addition, the analysis of multipath combinations reveals that the problem of satellite-induced code biases found in BDS-2 seems to have been solved for BDS-3. Precise orbit and clock determination are carried out and evaluated. The orbit overlap comparison show a precision of 2-6 dm in 3D root mean square (RMS) and 6-14 cm in the radial component for experimental BDS-3 satellites. External validations with satellite laser ranging (SLR) show residual RMS on the level of 1-3 dm. Finally, the performance of the new-generation onboard atomic clocks is evaluated and results confirm an increased stability compared to BDS-2 satellite clocks.

20.
Sensors (Basel) ; 17(3)2017 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-28264424

RESUMEN

Ionospheric delay effect is a critical issue that limits the accuracy of precise Global Navigation Satellite System (GNSS) positioning and navigation for single-frequency users, especially in mid- and low-latitude regions where variations in the ionosphere are larger. Kriging spatial interpolation techniques have been recently introduced to model the spatial correlation and variability of ionosphere, which intrinsically assume that the ionosphere field is stochastically stationary but does not take the random observational errors into account. In this paper, by treating the spatial statistical information on ionosphere as prior knowledge and based on Total Electron Content (TEC) semivariogram analysis, we use Kriging techniques to spatially interpolate TEC values. By assuming that the stochastic models of both the ionospheric signals and measurement errors are only known up to some unknown factors, we propose a new Kriging spatial interpolation method with unknown variance components for both the signals of ionosphere and TEC measurements. Variance component estimation has been integrated with Kriging to reconstruct regional ionospheric delays. The method has been applied to data from the Crustal Movement Observation Network of China (CMONOC) and compared with the ordinary Kriging and polynomial interpolations with spherical cap harmonic functions, polynomial functions and low-degree spherical harmonic functions. The statistics of results indicate that the daily ionospheric variations during the experimental period characterized by the proposed approach have good agreement with the other methods, ranging from 10 to 80 TEC Unit (TECU, 1 TECU = 1 × 1016 electrons/m²) with an overall mean of 28.2 TECU. The proposed method can produce more appropriate estimations whose general TEC level is as smooth as the ordinary Kriging but with a smaller standard deviation around 3 TECU than others. The residual results show that the interpolation precision of the new proposed method is better than the ordinary Kriging and polynomial interpolation by about 1.2 TECU and 0.7 TECU, respectively. The root mean squared error of the proposed new Kriging with variance components is within 1.5 TECU and is smaller than those from other methods under comparison by about 1 TECU. When compared with ionospheric grid points, the mean squared error of the proposed method is within 6 TECU and smaller than Kriging, indicating that the proposed method can produce more accurate ionospheric delays and better estimation accuracy over China regional area.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA