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Ding K.,Hohai University | Feng L.,Hohai University | Qin S.-Y.,Hohai University | Mao J.,State Key Laboratory of PV Science and Technology | And 4 more authors.
Journal of Power Electronics | Year: 2016

Usually, the output characteristics of a photovoltaic (PV) array are significantly affected by non-uniform irradiance which is caused by ambient obstacles, clouds, orientations, tilts, etc. Some local maximum power points (LMPP) in the current-voltage (I-V) curves of a PV array can result in power losses of the array. However, the output power at the global maximum power point (GMPP) is different in different interconnection schemes in a PV array. Therefore, based on the theoretical analysis and mathematical derivation of different topological structures of a PV array, this paper investigated the output characteristics of dual series PV arrays with different interconnections. The proposed mathematical models were also validated by experimental results. Finally, this paper also concluded that in terms of performance, the total cross tied (TCT) interconnection was not always the optimal structure, especially in a dual series PV array. When one of the PV modules was severely mismatched, the TCT worked worse than the series parallel (SP) structure. This research can provide guidance for switching the interconnection to gain the greatest energy yield in a changeable- structure PV system. © 2016 KIPE. Source


Han G.,Hohai University | Han G.,Changzhou Key Laboratory of Photovoltaic System Integration and Production Equipment Technology | Qian A.,Hohai University | Zhang C.,Hohai University | And 2 more authors.
International Journal of Distributed Sensor Networks | Year: 2014

Recently underwater acoustic sensor networks (UASNs) have drawn much attention because of their great value in many underwater applications where human operation is hard to carry out. In this paper, we introduce and compare the performance of four localization algorithms in UASNs, namely, distance vector-hop (DV-hop), a new localization algorithm for underwater acoustic sensor networks (NLA), large-scale hierarchical localization (LSHL), and localization scheme for large scale underwater networks (LSLS). The four algorithms are all suitable for large-scale UASNs. We compare the localization algorithms in terms of localization coverage, localization error, and average energy consumption. Besides, we analyze the impacts of the ranging error and the number of anchor nodes on the performance of the localization algorithms. Simulations show that LSHL and LSLS perform much better than DV-hop and NLA in localization coverage, localization error, and average energy consumption. The performance of NLA is similar to that of the DV-hop. The advantage of DV-hop and NLA is that the localization results do not rely on the number of anchor nodes; that is, only a small number of anchor nodes are needed for localization. © 2014 Guangjie Han et al. Source


Zhu C.,Hohai University | Zhu C.,Guangdong University of Petrochemical Technology | Wang Y.,Hohai University | Han G.,Hohai University | And 4 more authors.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

Traditional data gathering protocols in wireless sensor networks are mainly based on static sink, and data are routed in a multi-hop manner towards sink. In this paper, we proposed a location predictable data gathering protocol with a mobile sink. A sink’s location prediction principle based on loose time synchronization is introduced. By calculating the mobile sink location information, every source node in the network is able to route data packets timely to the mobile sink through multi-hop relay. This study also suggests a dwelling time dynamic adjustment method, which takes the situation that different areas may generate different amount of data into account, resulting in a balanced energy consumption among nodes. Simulation results show that our data gathering protocol enables data routing with less data transmitting time delay and balance energy consumption among nodes. © Springer-Verlag Berlin Heidelberg 2015. Source


Wang F.,Hohai University | Wang F.,Guangdong University of Petrochemical Technology | Wang F.,Changzhou University | Han G.,Hohai University | And 4 more authors.
International Journal of Distributed Sensor Networks | Year: 2014

Balancing energy consumption and prolonging network lifetime have been hot topics in energy limited wireless sensor networks (WSNs). It is generally known that multiple sensor nodes collaborating with each other to perform tasks are an important means of energy balancing. In addition, a reasonable task allocation strategy is also an efficient method for task performing and energy saving. Furthermore, in order to save energy consumption, many WSNs are organized into clusters. Therefore, in this paper, we propose a distributed task allocation strategy for collaborative applications (DTAC) in cluster-based WSNs. In DTAC, the service abilities of sensor nodes are first evaluated and then the sensor nodes are classified into different ranking domains. Based on the service abilities of cluster members, the service ability of each cluster is calculated. A complex task can be first allocated to several clusters, and then scheduled on collaborative cluster members. Simulation results demonstrate that, compared with current related works, DTAC is much more efficient for complex task processing in terms of reducing energy consumption, shortening execution time, and balancing network loads. © 2014 Feng Wang et al. Source


Han G.,Hohai University | Han G.,Changzhou Key Laboratory of Photovoltaic System Integration and Production Equipment Technology | Jiang X.,Hohai University | Qian A.,Hohai University | And 2 more authors.
Scientific World Journal | Year: 2014

Recently, heterogeneous wireless sensor network (HWSN) routing protocols have drawn more and more attention. Various HWSN routing protocols have been proposed to improve the performance of HWSNs. Among these protocols, hierarchical HWSN routing protocols can improve the performance of the network significantly. In this paper, we will evaluate three hierarchical HWSN protocols proposed recently - EDFCM, MCR, and EEPCA - together with two previous classical routing protocols - LEACH and SEP. We mainly focus on the round of the first node dies (also called the stable period) and the number of packets sent to sink, which is an important aspect to evaluate the monitoring ability of a protocol. We conduct a lot of experiments and simulations on Matlab to analyze the performance of the five routing protocols. © 2014 Guangjie Han et al. Source

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