Active congestion quantification and reliability improvement considering aging failure in modern distribution networks

The enormous concerns of climate change and traditional resource crises lead to the increased use of distributed generations (DGs) and electric vehicles (EVs) in distribution networks. This leads to significant challenges in maintaining safe and reliable network operations due to the complexity and uncertainties in active distribution networks, e.g., congestion and reliability problems. Effective congestion management (CM) policies require appropriate indices to quantify the seriousness and customer contributions to congested areas. Developing an accurate model to identify the residual life of aged equipment is also essential in long-term CM procedures. The assessment of network reliability and equipment end-of-life failure also plays a critical role in network planning and regulation. The main contributions of this thesis include a) outlining the specific characteristics of congestion events and introducing the typical metrics to assess the effectiveness of CM approaches; b) proposing spatial, temporal and aggregate indices for rapidly recognizing the seriousness of congestion in terms of thermal and voltage violations, and proposing indices for quantifying the customer contributions to congested areas; c) proposing an improved method to estimate the end-of-life failure probabilities of transformers and cables lines taking real-time relative aging speed and loss-of-life into consideration; d) quantifying the impact of different levels of EV penetration on the network reliability considering end-of-life failure on equipment and post-fault network reconfiguration; and e) proposing an EV smart charging optimization model to improve network reliability and reduce the cost of customers and power utilities. Simulation results illustrate the feasibility of the proposed indices in rapidly recognizing the congestion level, geographic location, and customer contributions in balanced and unbalanced systems. Voltage congestion can be significantly relieved by network reconfiguration and the utilization of the proposed indices by utility operators in CM procedures is also explained. The numerical studies also verify that the improved Arrhenius-Weibull can better indicate the aging process and demonstrate the superior accuracy of the proposed method in identifying residual lives and end-of-life failure probabilities of transformers and conductors. The integration of EV has a great impact on equipment aging failure probability and loss-of-life, thus resulting in lower network reliability and higher cost for managing aging failure. Finally, the proposed piecewise linear optimization model of the EV smart charging framework can significantly improve network reliability by 90% and reduce the total cost by 83.8% for customers and power utilities

Jordan higher all-derivable points in triangular algebras

Let ${\mathcal{T}}$ be a triangular algebra. We say that $D=\{D_{n}: n\in N\}\subseteq L({\mathcal{T}})$ is a Jordan higher derivable mapping at $G$ if $D_{n}(ST+TS)=\sum_{i+j=n}(D_{i}(S)D_{j}(T)+D_{i}(T)D_{j}(S))$ for any $S,T\in {\mathcal{T}}$ with $ST=G$. An element $G\in {\mathcal{T}}$ is called a Jordan higher all-derivable point of ${\mathcal{T}}$ if every Jordan higher derivable linear mapping $D=\{D_{n}\}_{n\in N}$ at $G$ is a higher derivation. In this paper, under some mild conditions on ${\mathcal{T}}$, we prove that some elements of ${\mathcal{T}}$ are Jordan higher all-derivable points. This extends some results in [6] to the case of Jordan higher derivations.Comment: 15 page

An Efficient ΣΔ-STAP Detector for Radar Seeker using RPCA Post-processing

Adaptive detection of moving targets in sea clutter environment is considered as one of the crucial tasks for radar seekers. Due to the severe spreading of the sea clutter spectrum, the ability of space-time adaptive processing with sum and difference beams (ΣΔ-STAP) algorithms to suppress the sea clutter is very limited. This paper, investigated the low-rank property of the range-Doppler data matrix according to the eigenvalue distribution from the eigen spectrum, and proposed an efficient ΣΔ-STAP detector based on the robust principle component analysis (RPCA) algorithm to detect moving targets, which meets the low-rank matrix recovery conditions. The proposed algorithm first adopts ΣΔ-STAP algorithm to preprocess the sea clutter, then separates the sparse matrix of target component from the range-Doppler data matrix through the RPCA algorithm, and finally, effectively detects moving targets in the range-Doppler plane. Simulation results demonstrate the effectiveness and robustness of the proposed algorithm in the low signal-to-noise ratio scenarios.Defence Science Journal, Vol. 64, No. 4, July 2014, pp. 344-349, DOI:http://dx.doi.org/10.14429/dsj.64.486

Embryogenesis and plant regeneration from unpollinated ovaries of Amorphophallus konjac

The system of somatic embryogenesis of Amorphophallus konjac had been built through unpollinated ovaries. The embryogenic calli were induced on Murashige and Skoog (MS) basal medium supplemented with 9.0 μM 6- benzylaminopurine (BA), 0.4 μM 2,4dichlorophenoxyacetic acid (D), 1.0 μM naphthaleneacetic acid (NAA), and the induction rate was 34.0%. The differentiation rate was 35.5% on the medium of MS basal medium supplemented with 6.7 μM 6-BA and 2.2 μM NAA. The obtained plantlets were transferred into rooting medium which was 1/2MS supplementing with 2.7 μM NAA, and the rooting rate was above 95%. All of the media were added 3% (w/v) sucrose and 0.3% (w/v) phytagel, the experimental materials for each step were cultured at 25 ± 2°C with a photoperiod of 12 h and light intensity of 50 μmol m-2 s-1.Keywords: Amorphophallus konjac, unpollinated ovary, embryogenic calli, plant regeneratio

Cloud-structural health monitoring based on smartphone

Smartphone, integrated with CPU, sensors, network, and storage capability, is developed rapidly in recent years. A cloud-structural health monitoring method based on smartphone was proposed, and a structural health monitoring system Orion-CC, which integrates functions of data acquisition, data analysis and data upload, was developed on smartphone to perform structural health monitoring without any other professional devices. And the feasibility of Orion-CC was proved by the cable force test. A cloud-SHM data sharing website was built to make the data synchronization between smartphone and website, and realize data uploading and sharing, which can improve the efficiency of monitoring and big data integration, make the possibility for big data collection and quick structural safety evaluation

Variation of upper-ocean heat content in the Canada Basin in summers of 2003 and 2008

Conductivity, temperature, and depth data collected during the summers of 2003 and 2008 were used to study upper-ocean (top 200 m) heat content in the Canada Basin. The variation of heat content with depth, heat content differences between the summers, principal driving factors, and horizontal spatial scale differences were analyzed. A catastrophic reduction of sea ice cover in the Canada Basin was evident in 2008 by comparison with 2003, suggesting that more solar radiation was absorbed in the upper ocean during the summer of 2008. The sea ice reduction produced more freshwater in the upper ocean. Thus, seawater properties changed. The study shows that the huge reduction of sea ice would result in two changes-widespread warming of the upper ocean, and the depth of Pacific inflow water in the basin increased substantially. Near-surface temperature maximum (NSTM) water was also analyzed as an indicator of Arctic Ocean warming

Summer water temperature structures and their interannual variation in the upper Canada Basin

Conductivity, temperature and depth (CTD) data from 1993{2010 are used to study water temperature in the upper Canada Basin. There are four kinds of water temperature structures: The remains of the winter convective mixed layer, the near-surface temperature maximum (NSTM), the wind-driven mixed layer, and the advected water under sea ice. The NSTM mainly appears within the conductive mixed layer that forms in winter. Solar heating and surface cooling are two basic factors in the formation of the NSTM. The NSTM can also appear in undisturbed open water, as long as there is surface cooling. Water in open water areas may advect beneath the sea ice. The overlying sea ice cools the surface of the advected water, and a temperature maximum could appear similar to the NSTM. The NSTM mostly occurred at depths 10{30 m because of its deepening and strengthening during summer, with highest frequency at 20 m. Two clear stages of interannual variation are identified. Before 2003, most NSTMs were observed in marginal ice zones and open waters, so temperature maxima were usually warmer than 0°C. After 2004, most NSTMs occurred in ice-covered areas, with much colder temperature maxima. Average depths of the temperature maxima in most years were about 20 m, except for about 16 m in 2007, which was related to the extreme minimum of ice cover. Average temperatures were around {0.8°C to {1.1°C, but increased to around {0.5°C in 2004, 2007 and 2009, corresponding to reduced sea ice. As a no-ice summer in the Arctic is expected, the NSTM will be warmer with sea ice decline. Most energy absorbed by seawater has been transported to sea ice and the atmosphere. The heat near the NSTM is only the remains of total absorption, and the energy stored in the NSTM is not considerable. However, the NSTM is an important sign of the increasing absorption of solar energy in seawater