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  • 1
    Publikationsdatum: 2016-06-09
    Beschreibung: The purpose of this study was to compare the efficacy and tolerability of the Ahmed glaucoma valve (AGV) implant and the Baerveldt implant for the treatment of refractory glaucoma.
    Digitale ISSN: 1471-2415
    Thema: Medizin
    Publiziert von BioMed Central
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2018-05-15
    Beschreibung: Energies, Vol. 11, Pages 1242: Optimal Scheduling Strategies of Distributed Energy Storage Aggregator in Energy and Reserve Markets Considering Wind Power Uncertainties Energies doi: 10.3390/en11051242 Authors: Zengqiang Mi Yulong Jia Junjie Wang Xiaoming Zheng With continuous technological improvement and economic development of energy storage, distributed energy storage (DES) will be widely connected to the distribution network. If fragmented DES systems are aggregated to form a distributed energy storage aggregator (DESA), the DESA will have great potential to participate in the day-ahead energy and reserve market and the balancing market. The DESA could act as a mediator between the market and DES consumers, enabling beneficial coordination for DES owners and power systems. This paper presents a bilevel optimization model for DESAs in the energy and reserve market under wind power uncertainties. In the lower-level problem, generating companies, wind power plants (WPP), and DESAs are optimized for scheduling day-ahead (DA) energy and the reserve market. In the upper-level problem, operational strategies for DES systems and DESAs are designed to deal with wind power uncertainties in the balancing market. The DESA splits its resources between the energy and reserve markets so that it can reduce total power system consumption, and mutual profit for the system and end customers is achieved. This model is formulated as a mixed-integer linear programming (MILP) program, which can be solved with commercial software. The validity of the bilevel optimization model is verified by the eight-node test transmission system and IEEE-33 bus distribution system.
    Digitale ISSN: 1996-1073
    Thema: Energietechnik
    Publiziert von MDPI Publishing
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2014-07-14
    Beschreibung: This paper presents a hybrid model for early onset prediction of driver fatigue, which is the major reason of severe traffic accidents. The proposed method divides the prediction problem into three stages, that is, SVM-based model for predicting the early onset driver fatigue state, GA-based model for optimizing the parameters in the SVM, and PCA-based model for reducing the dimensionality of the complex features datasets. The model and algorithm are illustrated with driving experiment data and comparison results also show that the hybrid method can generally provide a better performance for driver fatigue state prediction.
    Print ISSN: 1024-123X
    Digitale ISSN: 1563-5147
    Thema: Mathematik , Technik allgemein
    Publiziert von Hindawi
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Publikationsdatum: 2018-03-09
    Beschreibung: IJGI, Vol. 7, Pages 85: Assessment of Multiple GNSS Real-Time SSR Products from Different Analysis Centers ISPRS International Journal of Geo-Information doi: 10.3390/ijgi7030085 Authors: Zhiyu Wang Zishen Li Liang Wang Xiaoming Wang Hong Yuan The real-time State Space Representation (SSR) product of the GNSS (Global Navigation Satellite System) orbit and clock is one of the most essential corrections for real-time precise point positioning (PPP). In this work, the performance of current SSR products from eight analysis centers were assessed by comparing it with the final product and the accuracy of real-time PPP. Numerical results showed that (1) the accuracies of the GPS SSR product were better than 8 cm for the satellite orbit and 0.3 ns for the satellite clock; (2) the accuracies of the GLONASS (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema) SSR product were better than 10 cm for orbit RMS (Root Mean Square) and 0.6 ns for clock STD (Standard Deviation); and (3) the accuracies of the BDS (BeiDou Navigation Satellite System) and Galileo SSR products from CLK93 were about 14.54 and 4.42 cm for the orbit RMS and 0.32 and 0.18 ns for the clock STD, respectively. The simulated kinematic PPP results obtained using the SSR products from CLK93 and CLK51 performed better than those using other SSR products; and the accuracy of PPP based on all products was better than 6 and 10 cm in the horizontal and vertical directions, respectively. The real-time kinematic PPP experiment carried out in Beijing, Tianjin, and Shijiazhuang, China indicated that the SSR product CLK93 from Centre National d’Etudes Spatiales (CNES) had a better performance than CAS01. Moreover, the PPP with GPS + BDS dual systems had a higher accuracy than those with only a GPS single system.
    Digitale ISSN: 2220-9964
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Publikationsdatum: 2018-02-16
    Beschreibung: Energies, Vol. 11, Pages 438: Power-Balancing Based Induction Machine Model for Power System Dynamic Analysis in Electromechanical Timescale Energies doi: 10.3390/en11020438 Authors: Ding Wang Xiaoming Yuan Meiqing Zhang Power balance, including active and reactive power, between the system supply and the demand from induction motor loads is a potentially necessary condition for system stable operation. Motion of system states depends on the balancing of active and reactive powers. Therefore, this paper proposes an induction machine model in electromechanical timescale from a power balancing viewpoint, in which the induction motor load is modeled as a voltage vector driven by power balancing between the system supply and the demand from induction motor load, so as to describe the dynamic characteristics of induction motor loads in a physical way for power system dynamic analysis. Then a voltage magnitude-phase dynamic analysis with the proposed induction machine model is constructed. Based on the voltage magnitude-phase dynamic analysis, the characteristics of grid-connected induction motor loads are explored, and the instability mechanisms of grid-connected induction motor loads induced by a large disturbance are discussed. It is shown that the dynamic behavior of grid-connected induction motor loads can be described as the dynamic process of the terminal voltage vector driven by coupled active and reactive power balancing in different timescales. In this way, the dynamic behavior of induction motor loads in terms of voltage magnitude-phase dynamics and its physical characteristics are clearly illustrated. Time-domain simulation results are presented to validate the above analyses.
    Digitale ISSN: 1996-1073
    Thema: Energietechnik
    Publiziert von MDPI Publishing
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Publikationsdatum: 2017-11-08
    Beschreibung: Water, Vol. 9, Pages 865: Cyanobacterial Nitrogen Fixation Influences the Nitrogen Removal Efficiency in a Constructed Wetland Water doi: 10.3390/w9110865 Authors: Xiaodong Zhang Xin Jia Liang Yan Jinzhi Wang Xiaoming Kang Lijuan Cui Nitrogen removal efficiency in constructed wetlands (CW) is influenced by multiple environmental factors. However, little is known about the role of cyanobacterial nitrogen fixation in affecting nitrogen removal efficiency. This study investigated how cyanobacterial nitrogen fixation affects the efficiency, at which a CW removes nitrogen from an associated artificial lake (AL) in Beijing. For this purpose, we measured cell densities of N-fixing and non-N-fixing cyanobacteria, the aquatic nitrogen fixation rate (RNfix), and the concentration of various nitrogen fractions over the growing season (April–November) of 2014 in both AL and CW. We found that the removal of particulate organic nitrogen (PON) contributed to >90% of the total nitrogen removal in the CW. The removal efficiency of PON was lower during August–October (55.45 ± 27.49%) than during April–July (68.86 ± 8.83%). Phytoplankton proliferation in summer, as one of the main sources of PON, may have exceeded the capacity of the CW and led to declines in PON removal efficiency. RNfix peaked in July–October (3–169 ng N·L−1·h−1) and was positively correlated with both PON concentration and the cell density of N-fixing Anabaena sp. over the growing season, suggesting that aquatic nitrogen fixation (primarily in the AL) may increase PON and thereby reduce the its removal efficiency in the CW.
    Digitale ISSN: 2073-4441
    Thema: Energietechnik
    Publiziert von MDPI Publishing
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Publikationsdatum: 2018-05-02
    Beschreibung: Sensors, Vol. 18, Pages 1385: Geometric Integration of Hybrid Correspondences for RGB-D Unidirectional Tracking Sensors doi: 10.3390/s18051385 Authors: Shengjun Tang Wu Chen Weixi Wang Xiaoming Li Walid Darwish Wenbin Li Zhengdong Huang Han Hu Renzhong Guo Traditionally, visual-based RGB-D SLAM systems only use correspondences with valid depth values for camera tracking, thus ignoring the regions without 3D information. Due to the strict limitation on measurement distance and view angle, such systems adopt only short-range constraints which may introduce larger drift errors during long-distance unidirectional tracking. In this paper, we propose a novel geometric integration method that makes use of both 2D and 3D correspondences for RGB-D tracking. Our method handles the problem by exploring visual features both when depth information is available and when it is unknown. The system comprises two parts: coarse pose tracking with 3D correspondences, and geometric integration with hybrid correspondences. First, the coarse pose tracking generates the initial camera pose using 3D correspondences with frame-by-frame registration. The initial camera poses are then used as inputs for the geometric integration model, along with 3D correspondences, 2D-3D correspondences and 2D correspondences identified from frame pairs. The initial 3D location of the correspondence is determined in two ways, from depth image and by using the initial poses to triangulate. The model improves the camera poses and decreases drift error during long-distance RGB-D tracking iteratively. Experiments were conducted using data sequences collected by commercial Structure Sensors. The results verify that the geometric integration of hybrid correspondences effectively decreases the drift error and improves mapping accuracy. Furthermore, the model enables a comparative and synergistic use of datasets, including both 2D and 3D features.
    Digitale ISSN: 1424-8220
    Thema: Chemie und Pharmazie , Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von MDPI Publishing
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Publikationsdatum: 2015-04-01
    Beschreibung: The effectiveness of grouting scheme has been simulated to prevent the coal spontaneous combustion at a goaf in Haizi Colliery, China. The colliery has been operated for long period over 27 years and has a complex ventilation network including airflow leakages which could possibly lead to the spontaneous combustion of coal at goafs. Firstly, the mine ventilation simulator MIVENA was used to analyze the mine ventilation network airflows to control airflows in and out of working faces and goafs. As the second approach, numerical simulations were carried by the simulator FLUENT in order to predict spontaneous combustion of residual coal with leakage flow in the #3205 goaf. It was cleared that the goaf can be divided into three zones based on oxygen concentration in the goaf area. Finally, the numerical simulation results show that the slurry grouting method is able to be an effective and economical method by reducing porosity in the goaf area to prevent spontaneous combustion of residual coal.
    Print ISSN: 1687-8833
    Digitale ISSN: 1687-8841
    Thema: Geologie und Paläontologie
    Publiziert von Hindawi
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Publikationsdatum: 2015-07-04
    Beschreibung: Background: The purpose of this study was to examine the choroidal thickness of patients with high myopia using enhanced depth imaging optical coherence tomography (EDI-OCT) and compare them with healthy subjects. Methods: We first conducted a cross-sectional study and then performed a meta-analysis to address this issue further. Using enhanced depth imaging optical coherence tomography (EDI-OCT), the macular choroidal thickness of high myopic eyes and normal control eyes were measured and compared at each location. Univariate and multivariate linear regression analyses were performed to assess the association between choroidal thickness and clinical factors such as axial length (AL), spherical equivalent (SE), and central corneal thickness. In the high myopic eyes, subgroup analysis of macular choroidal thickness was performed in eyes with or without lacquer cracks and choroidal neovascularization (CNV). The meta-analyses were conducted using the Stata software package. Results: The high myopic eyes had a thinner choroid than the control eyes at all macular locations (all P 
    Digitale ISSN: 1471-2415
    Thema: Medizin
    Publiziert von BioMed Central
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Publikationsdatum: 2015-04-30
    Beschreibung: Background: Hepatocyte carcinoma (HCC) is one of the most common malignancies worldwide. Despite many achievements in diagnosis and treatment, HCC mortality remains high due to the malignant nature of the disease. Novel approaches, especially for targeted therapy, are being extensively explored. Gene therapy is ideal for such purpose for its specific expression of exogenous genes in HCC cells driven by tissue-specific promoter. However strategies based on correction of mutations or altered expressions of genes responsible for the development/progression of HCC have limitations because these aberrant molecules are not presented in all cancerous cells. In the current work, we adopted a novel strategy by targeting the DNA replication step which is essential for proliferation of every cancer cell. Methods: A recombinant adenovirus with alpha fetoprotein (AFP) promoter-controlled expressions of artificial microRNAs targeting DNA polymerases α, δ, ε and recombinant active Caspase 3, namely Ad/AFP-Casp-AFP-amiR, was constructed. Results: The artificial microRNAs could efficiently inhibit the expression of the target polymerases in AFP-positive HCC cells at both RNA and protein levels, and HCC cells treated with the recombinant virus Ad/AFP-Casp-AFP-amiR exhibited significant G0/1 phase arrest. The proliferation of HCC cells were significantly inhibited by Ad/AFP-Casp-AFP-amiR with increased apoptosis. On the contrary, the recombinant adenovirus Ad/AFP-Casp-AFP-amiR did not inhibit the expression of DNA polymerases α, δ or ε in AFP-negative human normal liver cell HL7702, and showed no effect on the cell cycle progression, proliferation or apoptosis. Conclusions: Inhibition of DNA polymerases α, δ and ε by AFP promoter-driven artificial microRNAs may lead to effective growth arrest of AFP-positive HCC cells, which may represent a novel strategy for gene therapy by targeting the genes that are essential for the growth/proliferation of cancer cells, avoiding the limitations set by any of the individually altered gene.
    Digitale ISSN: 1471-2407
    Thema: Medizin
    Publiziert von BioMed Central
    Standort Signatur Einschränkungen Verfügbarkeit
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