Advanced Metering Infrastructure （AMI） enables smart grids to involve power consumers in the business process of power generation transmission, distribution and consumption. However, the participant of consumers cha...Advanced Metering Infrastructure （AMI） enables smart grids to involve power consumers in the business process of power generation transmission, distribution and consumption. However, the participant of consumers challenges the current power systems with system integration and cooperation and security issues. In this paper, the authors introduce a service-oriented approach to AMI aiming at solving the intercommunication problem and meanwhile providing a trust and secure environment for smart grids. In this approach heterogeneous systems expose services to the network. System integration and cooperation are done through service composition. A generic service interfacing method is designed to develop standardized services for heterogeneous power systems. Moreover, role-based access control mechanism is used to guarantee the secure access to smart grids. With the seamless communication between consumers and power systems and among power systems themselves, this service-oriented AMI can associate consumers with actual system workload and furthermore support the intelligent running of power systems.展开更多
A complex longitudinal magnetoresistance （MR//） effect in the non-stoichiometric silver chaJcogenides （include the silver selenide and telluride） has been found, however the mechanism for the MR// effect is not cl...A complex longitudinal magnetoresistance （MR//） effect in the non-stoichiometric silver chaJcogenides （include the silver selenide and telluride） has been found, however the mechanism for the MR// effect is not clear now. In this work, a new random resistor network for MR// effect is proposed based on the experimental observation. The network is constructed from six-terminal resistor units and the mobility of carries within the network has a Gaussian distribution. Considering the non-zero transverse-longitudinal coupling in materials, the resistance matrix of the six- terminal resistor unit is modified. It is found that the material has the ＂chiral＂ transverse-longitudinal couplings, which is suggested a main reason for the complex MR//effect. The model predictions are compared with the experimental results. A three dimension （3D） visualization of current flow within the network demonstrates the ＂current jets＂ phenomenon in the thickness of materials dearly.展开更多
A distribution grid is generally characterized by a high R/X （resistance/reactance） ratio and it is radial in nature. By design, a distribution grid system is not an active network, and it is normally designed in su...A distribution grid is generally characterized by a high R/X （resistance/reactance） ratio and it is radial in nature. By design, a distribution grid system is not an active network, and it is normally designed in such a way that power flows from transmission system via distribution system to consumers. But in a situation when wind turbines are connected to the distribution grid, the power source will change from one source to two sources, in this case, network is said to be active. This may probably have an impact on the distribution grid to whenever the wind turbine is connected. The best way to know the impact of wind turbine on the distribution grid in question is by carrying out load flow analysis on that system with and without the connection of wind turbines. Two major fundamental calculations： the steady-state voltage variation at the PCC （point of common coupling） and the calculation of short-circuit power of the grid system at the POC （point of connection） are necessary before carrying out the load flow study on the distribution grid. This paper, therefore, considers these pre-load flow calculations that are necessary before carrying out load flow study on the test distribution grid. These calculations are carded out on a test distribution system.展开更多
BaFe10A12O19/poly（m-toluidine） （BFA/PMT） composites were synthesized by in-situ polymerization of m-toluidine in the presence of BaFe10Al2O19 particles. The structure, composition and morphology of the obtained sa...BaFe10A12O19/poly（m-toluidine） （BFA/PMT） composites were synthesized by in-situ polymerization of m-toluidine in the presence of BaFe10Al2O19 particles. The structure, composition and morphology of the obtained samples were characterized by using XRD, FT-IR, UV-visible spectroscopy, SEM and TEM techniques. Their electrical conductivity, magnetic property and microwave absorbing property were measured by the four-probe meter, the vibrating sample magnetometer and the vector network analyzer, respectively. The results indicated that BFA particles were coated effectively by PMT polymer and some interactions between PMT and BFA particles existing in the composites. The conductivity of BFA/PMT composite is smaller than that of pure polymers and its saturation magnetization is a little smaller than that of pure BFA. The influence of the constitution and film thickness of absorbent on its microwave absorbing property is evident. The microwave absorbing properties of the BFA/PMT composites are better than those of pure BFA and PMT. When optimizing the mass rate of BFA/PMT to 0.3, the absorbent with 2 mm film thickness has the minimum reflection loss of -28.26 dB at approximate 14.24 GHz, and the maximum available bandwidth of 8.8 GHz, respectively. The results show that these composites can be used as advancing absorption and shielding materials due to their favorable microwave absorbing property.展开更多
文摘Advanced Metering Infrastructure （AMI） enables smart grids to involve power consumers in the business process of power generation transmission, distribution and consumption. However, the participant of consumers challenges the current power systems with system integration and cooperation and security issues. In this paper, the authors introduce a service-oriented approach to AMI aiming at solving the intercommunication problem and meanwhile providing a trust and secure environment for smart grids. In this approach heterogeneous systems expose services to the network. System integration and cooperation are done through service composition. A generic service interfacing method is designed to develop standardized services for heterogeneous power systems. Moreover, role-based access control mechanism is used to guarantee the secure access to smart grids. With the seamless communication between consumers and power systems and among power systems themselves, this service-oriented AMI can associate consumers with actual system workload and furthermore support the intelligent running of power systems.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 50872038 and 10675048
文摘A complex longitudinal magnetoresistance （MR//） effect in the non-stoichiometric silver chaJcogenides （include the silver selenide and telluride） has been found, however the mechanism for the MR// effect is not clear now. In this work, a new random resistor network for MR// effect is proposed based on the experimental observation. The network is constructed from six-terminal resistor units and the mobility of carries within the network has a Gaussian distribution. Considering the non-zero transverse-longitudinal coupling in materials, the resistance matrix of the six- terminal resistor unit is modified. It is found that the material has the ＂chiral＂ transverse-longitudinal couplings, which is suggested a main reason for the complex MR//effect. The model predictions are compared with the experimental results. A three dimension （3D） visualization of current flow within the network demonstrates the ＂current jets＂ phenomenon in the thickness of materials dearly.
文摘A distribution grid is generally characterized by a high R/X （resistance/reactance） ratio and it is radial in nature. By design, a distribution grid system is not an active network, and it is normally designed in such a way that power flows from transmission system via distribution system to consumers. But in a situation when wind turbines are connected to the distribution grid, the power source will change from one source to two sources, in this case, network is said to be active. This may probably have an impact on the distribution grid to whenever the wind turbine is connected. The best way to know the impact of wind turbine on the distribution grid in question is by carrying out load flow analysis on that system with and without the connection of wind turbines. Two major fundamental calculations： the steady-state voltage variation at the PCC （point of common coupling） and the calculation of short-circuit power of the grid system at the POC （point of connection） are necessary before carrying out the load flow study on the distribution grid. This paper, therefore, considers these pre-load flow calculations that are necessary before carrying out load flow study on the test distribution grid. These calculations are carded out on a test distribution system.
基金supported by the National Nature Science Foundation of China (21071125)the Natural Science Foundation of Zhejiang Province(Y4100022,Y4090636)the Science and Technology Key Project of Zhejiang Province (2010C11053)
文摘BaFe10A12O19/poly（m-toluidine） （BFA/PMT） composites were synthesized by in-situ polymerization of m-toluidine in the presence of BaFe10Al2O19 particles. The structure, composition and morphology of the obtained samples were characterized by using XRD, FT-IR, UV-visible spectroscopy, SEM and TEM techniques. Their electrical conductivity, magnetic property and microwave absorbing property were measured by the four-probe meter, the vibrating sample magnetometer and the vector network analyzer, respectively. The results indicated that BFA particles were coated effectively by PMT polymer and some interactions between PMT and BFA particles existing in the composites. The conductivity of BFA/PMT composite is smaller than that of pure polymers and its saturation magnetization is a little smaller than that of pure BFA. The influence of the constitution and film thickness of absorbent on its microwave absorbing property is evident. The microwave absorbing properties of the BFA/PMT composites are better than those of pure BFA and PMT. When optimizing the mass rate of BFA/PMT to 0.3, the absorbent with 2 mm film thickness has the minimum reflection loss of -28.26 dB at approximate 14.24 GHz, and the maximum available bandwidth of 8.8 GHz, respectively. The results show that these composites can be used as advancing absorption and shielding materials due to their favorable microwave absorbing property.
