Existing studies about two-dimensional consecutivek-out-of-n： F system is dealt with two states （either component or system）： working or failure. A new model for two-dimensional linear consecutive-k-out-of-n： F s...Existing studies about two-dimensional consecutivek-out-of-n： F system is dealt with two states （either component or system）： working or failure. A new model for two-dimensional linear consecutive-k-out-of-n： F system is proposed, in which the components and systems can be at any of the three states： full working, derating working, and failure. Furthermore, two engineer- ing concrete instances of the new system are given. By using the finite Markov chain imbedding approach, the system reliability is presented in a unified formula with the product of matrices for the case of independent and identically distributed component states which can be extended to the independent but non-identical case easily. Finally, an example is given to illustrate the effectiveness of the above approach and tractability of various problems.展开更多
The electrochemical behaviour of Y￣(3+) and Ba￣(2+) on platinum and copper electrode in molten YF_3(70 wt% )-NaF (20 wt%)-CaF_2(10 wt%) has been studied by means of cyclic voltammetry. discharge curve and so on. Th...The electrochemical behaviour of Y￣(3+) and Ba￣(2+) on platinum and copper electrode in molten YF_3(70 wt% )-NaF (20 wt%)-CaF_2(10 wt%) has been studied by means of cyclic voltammetry. discharge curve and so on. The Y-Ba-Cu alloy is obtained by fused salt electrolysis with molten YF_3-NaF-CaF_2 as electrolyte and Y_2O_3 and BaO as raw materials. Graphite cell acted as an anode and copper rod as consumable cathode. The molten bath temperature was 1193 K. Cathode current density was 20 A/cm￣2. The contents of yttrium, barium and copper in alloy were about 20wt%, 9 wt% and 71 wt% respectively. Yttrium recovery efficiency was 90 wt%. The current efficiency was 70%～80 %.展开更多
Asymmetric three-phase cascading Trinary-DC source Multilevel Inverter which can achieve reduced harmonics and superior root mean square (RMS) values of the output voltage is proposed. This topology can achieve cascad...Asymmetric three-phase cascading Trinary-DC source Multilevel Inverter which can achieve reduced harmonics and superior root mean square (RMS) values of the output voltage is proposed. This topology can achieve cascaded full bridge inverter operation with dissimilar (unequal) DC Source and it is fired by using variable frequency pulse with modulation technique as a switching strategy. This pulse width modulation switching strategy has a newly adopted multicarrier single reference technique. The performance parameter factors like Form Factor (FF), Crest Factor (CF), Total Harmonic Distortion (THD) and fundamental RMS output voltage (V<sub>RMS</sub>) are estimated by using proposed asymmetrical three-phase cascading multilevel inverter for several modulation indices (0.8 - 1). The research study carries with MATLAB/SIMULINK based simulation and experimental results obtained using appropriate prototype (test board) to prove the viability of the proposed concept.展开更多
Three new kinds of self-assembled films were first fabricated through a new strategy. These films have Sn4+, Zr4+ and Ce4+ as bridging central ions, 3, 4, 9, 10-perylene tetracarboxylic acid (PTA) as functional molecu...Three new kinds of self-assembled films were first fabricated through a new strategy. These films have Sn4+, Zr4+ and Ce4+ as bridging central ions, 3, 4, 9, 10-perylene tetracarboxylic acid (PTA) as functional molecules and oxalic acid as connecting ligand. All films were characterized by contact angle, UV spectra, X-ray photoelectron spectra (XPS) and cyclic voltammetry. The effects of light intensity, bias voltage, and electron donor on photocurrents of these films were also studied.展开更多
The harmonious chromatic number of a graph G, denoted by h(G), is the leastnumber of colors needed to color the vertices of G in such a way that adarent verticesare colored by different colors and any two distinct edg...The harmonious chromatic number of a graph G, denoted by h(G), is the leastnumber of colors needed to color the vertices of G in such a way that adarent verticesare colored by different colors and any two distinct edges receive dmerent color pairs- D.Johnson has shown that the problem of determiniug h(G) is a NP-hard problem. In thispaper we determine the exact value of the harmonious chromatic number of a completetrinary tree.展开更多
A series of sulfated binary and trinary oxide solid superacids were prepared, and their catalytic activities for n-butane isomerization at low temperature were measured. The incorporation of different metal oxides int...A series of sulfated binary and trinary oxide solid superacids were prepared, and their catalytic activities for n-butane isomerization at low temperature were measured. The incorporation of different metal oxides into ZrO2 may produce a positive or negative effect on the acid strength and catalytic activity of the solid superacids. Sulfated oxides of Cr-Zr, Fe-Cr-Zr and Fe-V-Zr are 2 - 3 times more active than the reported sulfated Fe-Mn-Zr oxide. The enhancement in the superacidity and catalytic activity of these new solid superacids has been discussed on account of the results of various characteriation techniques.展开更多
基金supported by the National Natural Science Foundation of China (70901008)the Specialized Research Fund for the Doctoral Program of Higher Education (20091101120053)+1 种基金the Excellent Young Scholars Research Fund of Beijing Institute of Technology (2008Y0818,2010YS1304)the Excellent Talent Culture Foundation of Beijing(2009D013001000040)
文摘Existing studies about two-dimensional consecutivek-out-of-n： F system is dealt with two states （either component or system）： working or failure. A new model for two-dimensional linear consecutive-k-out-of-n： F system is proposed, in which the components and systems can be at any of the three states： full working, derating working, and failure. Furthermore, two engineer- ing concrete instances of the new system are given. By using the finite Markov chain imbedding approach, the system reliability is presented in a unified formula with the product of matrices for the case of independent and identically distributed component states which can be extended to the independent but non-identical case easily. Finally, an example is given to illustrate the effectiveness of the above approach and tractability of various problems.
文摘The electrochemical behaviour of Y￣(3+) and Ba￣(2+) on platinum and copper electrode in molten YF_3(70 wt% )-NaF (20 wt%)-CaF_2(10 wt%) has been studied by means of cyclic voltammetry. discharge curve and so on. The Y-Ba-Cu alloy is obtained by fused salt electrolysis with molten YF_3-NaF-CaF_2 as electrolyte and Y_2O_3 and BaO as raw materials. Graphite cell acted as an anode and copper rod as consumable cathode. The molten bath temperature was 1193 K. Cathode current density was 20 A/cm￣2. The contents of yttrium, barium and copper in alloy were about 20wt%, 9 wt% and 71 wt% respectively. Yttrium recovery efficiency was 90 wt%. The current efficiency was 70%～80 %.
文摘Asymmetric three-phase cascading Trinary-DC source Multilevel Inverter which can achieve reduced harmonics and superior root mean square (RMS) values of the output voltage is proposed. This topology can achieve cascaded full bridge inverter operation with dissimilar (unequal) DC Source and it is fired by using variable frequency pulse with modulation technique as a switching strategy. This pulse width modulation switching strategy has a newly adopted multicarrier single reference technique. The performance parameter factors like Form Factor (FF), Crest Factor (CF), Total Harmonic Distortion (THD) and fundamental RMS output voltage (V<sub>RMS</sub>) are estimated by using proposed asymmetrical three-phase cascading multilevel inverter for several modulation indices (0.8 - 1). The research study carries with MATLAB/SIMULINK based simulation and experimental results obtained using appropriate prototype (test board) to prove the viability of the proposed concept.
文摘Three new kinds of self-assembled films were first fabricated through a new strategy. These films have Sn4+, Zr4+ and Ce4+ as bridging central ions, 3, 4, 9, 10-perylene tetracarboxylic acid (PTA) as functional molecules and oxalic acid as connecting ligand. All films were characterized by contact angle, UV spectra, X-ray photoelectron spectra (XPS) and cyclic voltammetry. The effects of light intensity, bias voltage, and electron donor on photocurrents of these films were also studied.
文摘The harmonious chromatic number of a graph G, denoted by h(G), is the leastnumber of colors needed to color the vertices of G in such a way that adarent verticesare colored by different colors and any two distinct edges receive dmerent color pairs- D.Johnson has shown that the problem of determiniug h(G) is a NP-hard problem. In thispaper we determine the exact value of the harmonious chromatic number of a completetrinary tree.
基金Project supported by the State Key Projects for Fundamental ResearchChina Petrochemical Corporation
文摘A series of sulfated binary and trinary oxide solid superacids were prepared, and their catalytic activities for n-butane isomerization at low temperature were measured. The incorporation of different metal oxides into ZrO2 may produce a positive or negative effect on the acid strength and catalytic activity of the solid superacids. Sulfated oxides of Cr-Zr, Fe-Cr-Zr and Fe-V-Zr are 2 - 3 times more active than the reported sulfated Fe-Mn-Zr oxide. The enhancement in the superacidity and catalytic activity of these new solid superacids has been discussed on account of the results of various characteriation techniques.
