Performance Evaluation for Medium Voltage MIMO-OFDM Power Line Communication System

Power line communication(PLC)provides intelligent electrical functions such as power quality measurement,fault surveys,and remote control of electrical network.Most of research works have been done in low voltage(LV)scenario due to the fast development of in-home PLC.The aim of this paper is to evaluate the link-level performance of a medium voltage(MV)MIMO-OFDM communication system based on transmission link under underground power line channel.The MIMO channel is modeled as a modified multipath model in the presence of impulsive noise and background noise.We first perform a measurement on the practical MV MIMO channel parameters for a section of buried cable of 1 km long in Ganzhou city,Jiangxi province,China.Based on the measured channel,we design the frame structure based on an IEEE standard for broadband over power line networks[1]to support MV MIMO-OFDM transmission.According to designed frame structure,we design an encoder and a decoder for a dual binary tail-biting turbo code and optimize some key decoder parameters for low bit error rate performance.Finally,the link-level performance for both spatial multiplexing and spatial diversity are evaluated.Numeral results show that MV MIMO-OFDM is a promising approach to provide both high data rate and link reliability for PLC.

Bouquet-like uranium-containing selenotungstate consisting of two different Keggin-/Anderson-type units with excellent photoluminescence quantum yield

We present the synthesis,characterization and photoluminescence properties of uranium-containing selenotungstate,[(UO_(2))_(3)(SeO_(3))_(3)Na_(5)(H_(2)O)_(6)(SeW_(6)O_(21))(SeW_(9)O_(33))_(3)]^(21–),which was isolated by a one-pot reaction of uranium nitrate with sodium tungstate and sodium selenite in a pH 5.2 aqueous solution at 90°C.In this study,the effect of the introduction of lone-electron pair containing heteroatoms on the structure is demonstrated,a three-layered heterometallic{Se_(3)U_(3)Na_(5)}cluster is encapsulated by two different anionic building block units:three trivacant Keggin{B-α-Se W_(9)O_(33)}and one Anderson{SeW_(6)O_(21)}.To our knowledge,the{Se_(3)U_(3)Na_(5)}cluster has never been observed in the polyoxometalate chemistry.The solidstate photoluminescence properties and lifetime decay behaviours of the title compound(1)have been measured at room temperature,and the photoluminescence spectrum displays the characteristic emission bands of corresponding uranyl cations.In addition,the photoluminescence quantum yield of 1 is 72%,which is almost three times that of starting material UO_(2)(NO_(3))_(2)·6H_(2)O(27%).By using this strategy,we envision that an increasing number of assemblies with‘open’clusters may be designed and obtained,in which the exposed oxygen atoms show strong affinity towards metal ions,providing new opportunities to generate bigger clusters or to tune existing properties.

H_(4)SiW_(12)O_(40)-catalyzed cyclization of epoxides/aldehydes and sulfonyl hydrazides: An efficient synthesis of 3,4-disubstituted 1H-pyrazoles

A simple and efficient method for the synthesis of pyrazoles through a silicotungstic acid (H_(4)SiW_(12)O_(40))-catalyzed cyclization of epoxides/aldehydes and sulfonyl hydrazides has been developed. Various epoxides/aldehydes were smoothly reacted with sulfonyl hydrazides to furnish regioselectivity 3,4-disubstituted 1H-pyrazoles. The application of such an earth-abundant, readily accessible, and nontoxic catalyst provides a green approach for the construction of 3,4-disubstituted 1H-pyrazoles. A plausible reaction mechanism has been proposed on the basis of control experiments, GC-MS and DFT calculations.

Two Dawson-type U(Ⅵ)-containing selenotungstates with sandwich structure and its high-efficiency catalysis for pyrazoles

Two novel uranium-containing selenotungstates Na_(3)[H_(19)(UO_(2))_(2)(μ_(2)-O)(Se_(2)W_(14)O_(52))_(2)]·41 H_(2)O(U_(2))and(NH_(4))_(10)[H_(4)(SeO)_(2)(UO_(2))_(2)(H_(2)O)_(2)(H_(2)Se_(2)W_(14)O_(52))(Se_(2)W_(14)O_(52))]·66 H_(2)O(Se_(2)U_(2))based on the{Se_(2)W_(14)O_(52)}unit were successfully prepared and fully characterized.To our knowledge,the uranium is firstly introduced into the selenotungstates.Moreover,it is notable that U_(2)exhibits excellent Lewis acid-base catalytic activities in the condensation cyclization of sulfonyl hydrazides with diketones to synthesize polysubstituted pyrazoles.All the desired products were obtained in moderate to good yields(up to 99%).