In this paper, we focus on the design of irregular QC-LDPC code based multi-level coded modulation(MLCM) scheme by jointly optimizing the component code rate and the degree distribution of the irregular QC-LDPC compon...In this paper, we focus on the design of irregular QC-LDPC code based multi-level coded modulation(MLCM) scheme by jointly optimizing the component code rate and the degree distribution of the irregular QC-LDPC component code. Firstly, the sub-channel capacities of MLCM systems is analyzed and discussed, based on which the optimal component code rate can be obtained. Secondly, an extrinsic information transfer chart based two-stage searching algorithm is proposed to find the good irregular QC-LDPC code ensembles with optimal component code rates for their corresponding sub-channels. Finally, by constructing the irregular QC-LDPC component codes from the designed ensembles with the aim of possibly enlarging the girth and reducing the number of the shortest cycles, the designed irregular QC-LDPC code based 16QAM and 64QAM MLCM systems can achieve 0.4 dB and 1.2 dB net coding gain, respectively, compared with the recently proposed regular QC-LDPC code based 16QAM and 64QAM MLCM systems.展开更多
Heterogeneously catalyzed hydrolytic dehydrogenation of ammonia borane is a remarkable structure sensitive reaction. In this work, a strategy by using polyoxometalates(POMs) as the ligands is proposed to engineer the ...Heterogeneously catalyzed hydrolytic dehydrogenation of ammonia borane is a remarkable structure sensitive reaction. In this work, a strategy by using polyoxometalates(POMs) as the ligands is proposed to engineer the surface and electronic properties of Pt/CNT catalysts toward the enhanced hydrogen generation rate and durability. Three kinds of POMs, i.e., silicotungstic acid(STA), phosphotungstic acid(PTA)and molybdophosphoric acid(PMA), are comparatively studied, among which the STA shows positive effects on the catalytic activity and durability. A catalyst structure-performance relationship is established by a combination of kinetic and isotopic analyses with multiple characterization techniques, such as HAADF-STEM, EDS, Raman spectroscopy and XPS. It is shown that the STA compared to the other two POMs can increase the Pt binding energy and thus promote the reaction. The insights demonstrated here could open a new avenue for boosting the reaction by employing the POMs as the ligands to engineer the catalyst electronic properties.展开更多
Using glucose and sucrose as the electron donors,the photocatalytic hydrogen evolution over Pt/TiO2 was investigated.Glucose and sucrose enhance notably the activity for hydrogen generation.The amounts of produced H2 ...Using glucose and sucrose as the electron donors,the photocatalytic hydrogen evolution over Pt/TiO2 was investigated.Glucose and sucrose enhance notably the activity for hydrogen generation.The amounts of produced H2 increase almost proportionally to time within 5 h irradiation in the reaction systems of the two electron donors.The effect of the initial concentration of glucose and sucrose on the reaction rate is consistent with the Langmuir-Hinshelwood kinetic model.After 5 h irradiation,the COD（chemical oxygen demand） in the reaction system of glucose and in that of sucrose decrease by 33.2%,11.4% respectively.The effect of electron donors on the flat-band potential of conduction band of TiO2 electrode was investigated.The flat-band potential of conduction band of TiO2 electrode in the presence of the electron donors shifts negatively,and the shift in the presence of glucose is larger than that in the presence of sucrose due to glucose having a larger adsorption amount on TiO2.展开更多
基金supported by National Natural Science Foundation of China(No.61571061)
文摘In this paper, we focus on the design of irregular QC-LDPC code based multi-level coded modulation(MLCM) scheme by jointly optimizing the component code rate and the degree distribution of the irregular QC-LDPC component code. Firstly, the sub-channel capacities of MLCM systems is analyzed and discussed, based on which the optimal component code rate can be obtained. Secondly, an extrinsic information transfer chart based two-stage searching algorithm is proposed to find the good irregular QC-LDPC code ensembles with optimal component code rates for their corresponding sub-channels. Finally, by constructing the irregular QC-LDPC component codes from the designed ensembles with the aim of possibly enlarging the girth and reducing the number of the shortest cycles, the designed irregular QC-LDPC code based 16QAM and 64QAM MLCM systems can achieve 0.4 dB and 1.2 dB net coding gain, respectively, compared with the recently proposed regular QC-LDPC code based 16QAM and 64QAM MLCM systems.
基金supported by the National Natural Science Foundation of China(21776077)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning+3 种基金the Shanghai Rising-Star Program(17QA1401200)the Open Project of SKLOCE(SKL-Che-15C03)the Shanghai Natural Science Foundation(17ZR1407300 and 17ZR1407500)the State Key Laboratory of Organic-Inorganic Composites(oic201801007)。
文摘Heterogeneously catalyzed hydrolytic dehydrogenation of ammonia borane is a remarkable structure sensitive reaction. In this work, a strategy by using polyoxometalates(POMs) as the ligands is proposed to engineer the surface and electronic properties of Pt/CNT catalysts toward the enhanced hydrogen generation rate and durability. Three kinds of POMs, i.e., silicotungstic acid(STA), phosphotungstic acid(PTA)and molybdophosphoric acid(PMA), are comparatively studied, among which the STA shows positive effects on the catalytic activity and durability. A catalyst structure-performance relationship is established by a combination of kinetic and isotopic analyses with multiple characterization techniques, such as HAADF-STEM, EDS, Raman spectroscopy and XPS. It is shown that the STA compared to the other two POMs can increase the Pt binding energy and thus promote the reaction. The insights demonstrated here could open a new avenue for boosting the reaction by employing the POMs as the ligands to engineer the catalyst electronic properties.
文摘Using glucose and sucrose as the electron donors,the photocatalytic hydrogen evolution over Pt/TiO2 was investigated.Glucose and sucrose enhance notably the activity for hydrogen generation.The amounts of produced H2 increase almost proportionally to time within 5 h irradiation in the reaction systems of the two electron donors.The effect of the initial concentration of glucose and sucrose on the reaction rate is consistent with the Langmuir-Hinshelwood kinetic model.After 5 h irradiation,the COD（chemical oxygen demand） in the reaction system of glucose and in that of sucrose decrease by 33.2%,11.4% respectively.The effect of electron donors on the flat-band potential of conduction band of TiO2 electrode was investigated.The flat-band potential of conduction band of TiO2 electrode in the presence of the electron donors shifts negatively,and the shift in the presence of glucose is larger than that in the presence of sucrose due to glucose having a larger adsorption amount on TiO2.
