Beschreibung: Unusual cold filaments are uncovered during the spring intermonsoon season in the South China Sea (SCS) using a suite of satellite observations. They have a width of about 100 km on average and extend several hundreds of kilometers offshore on the sea surface, providing significant cross-shelf transport of heat and nutrients. The eastward current associated with mesoscale eddies in spring in the western SCS is found to play an important role in the filament formation by advecting coastal cold waters far offshore. The meridional location of the cold filament displays considerable interannual variability ranging between 9 o N and 18 o N, which can be attributed to the interannual south-north shift of the eastward current associated with eddies. It is also found that in the spring, cold filaments have profound effects on the chlorophyll a concentration in the upper ocean and the overlying atmosphere. These findings provide new insights into the role of eddies in cross-shelf exchange and mesoscale air-sea interaction in the marginal seas.

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.

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.

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.

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.

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.

Beschreibung: Abstract. The asymmetrical crystal [Na(15C5) 2 ][Na(15C5)] 2 (AsMo 12 O 40 )] · CH 3 CN ( 1 ) was synthesized. Interestingly, the huge α-keggin ion AsMo 12 is distorted by introduction of CH 3 CN molecules and adopts a chiral assembly with space group P 4 . In contrast, the analogous compound AsW 12 co-crystallizes with trace H 2 O molecules. The hydrogen atoms of H 2 O are positionally disordered with 50 % occupation to correlate with AsW 12 in space group P 4/ m . Solid and solution CD spectra indicate that the crystals of 1 are in R configuration. This leads to the conclusion that molybdenum has greater affinity toward organic CH 3 CN, whereas tungsten has greater affinity to inorganic H 2 O. Additionally, AsMo 12 shows greater deformability than AsW 12 . It is suggested that POMo shows a greater potential as chiral material than POW because of the flexibility of Mo. As a highlight, CH 3 CN can function as a general chiral inducer for the innovation of other chiral crystals, if fixed along one dimension.

Beschreibung: The cloud water content (CWC) in rainy clouds is a crucial parameter to determine the onset and the growth rate of precipitation, and to quantify the associated latent heating rate. No direct retrieval of CWC in rainy cloud from satellite observations is reported due to the difficulties of separating cloud particles from precipitation sized particles. However, based on multiple cloud simulations from the Weather and Research Forecasting (WRF) model, we have found that the CWC profile in warm rains can be well determined by three macro-physical cloud properties of cloud water path (CWP), cloud top height (CTH), and cloud bottom height (CBH). The CBH can be estimated using CWP, CTH and near surface rain rate. We proposed an algorithm with a lookup table for estimating the CWC profile using CWP, CTH and near surface rain rate as inputs. The performance of this algorithm was tested with WRF model simulations and a real drizzle case observed by the CloudSat satellite. Testing verified that the algorithm can retrieve the vertical distribution of CWC correctly with few errors at different spatiotemporal scales. In addition, the algorithm is not confined to particular microphysics schemes and is valid for multiple cloud systems in different areas over the world. This algorithm is expected to improve current knowledge of cloud water content in rainy clouds.

Beschreibung: Enterovirus 71 (EV71) usually causes hand-foot-and-mouth disease (HFMD) with severe clinical symptoms and even deaths in China. There is no efficient antiviral drug to protect against severe EV71-associated HFMD, making the development of EV71 vaccines therefore a priority. However, the potential target subject population(s) to be immunized with EV71 vaccine are not well understood. In this study, we characterized the epidemiology regarding EV71-associated HFMD on the basis of provincial-level surveillance. We extracted data on EV71-associated HFMD from the National Notifiable Disease Reporting System in Zhejiang Province, China between 1 January 2009 and 31 December 2013 (n = 7650). The higher incidence rate of EV71 cases occurred in those children aged 12–23 months, with boys being predominant. Interestingly, different peaks activities of EV71 infection was observed in different calendar year, with one peak in 2009 and 2013 and two peaks in 2010–2012. However, EV71 infection seemed to predominately occur in warm season and a distinguished cyclic peak that seemed to be of about 12 months. Children aged 12–23 months are thus identified as an important target population for public health intervention, for example, it is recommended that these key subjects immunized with EV71 vaccine. In addition, an enhanced surveillance system for EV71-associated with HFMD needs to focus on generic and phylogenetic analysis.

Beschreibung: Agricultural production, rural areas, and farmers are three key aspects of agriculture related to sustainable economic and social development in China. Rural development is a process of multi-participation, which involves actors from governments, village committees, villagers, rural economic cooperatives, enterprises, financing institutions, and non-government organizations (NGOs). Based on social network analysis (SNA), this article analyzes the social network structures and characteristics of various actors in different stages of rural development in Yanhe village, Hubei Province, China. The results show that both the village committee and villagers have great influence on rural development; NGOs are the leaders of rural environmental improvement; village cooperatives are the promoters of rural economic development; enterprises are the accelerators of rural construction and development. The study outlines the rural development model in Yanhe village where the village committee is the leader and multiple forms of participation and cooperation are present; there are excellent partnerships and communication mechanisms among the participants. The endogenous and sustainable development model identified from Yanhe village is valuable for other villages in China to adopt.