Organic solar cells with inverted planar heterojunction structure based on subphthalocya- nine and C60 were fabricated using several kinds of materials as cathode buffer layer （CBL）, including tris-8-hydroxy-quinoli...Organic solar cells with inverted planar heterojunction structure based on subphthalocya- nine and C60 were fabricated using several kinds of materials as cathode buffer layer （CBL）, including tris-8-hydroxy-quinolinato aluminum （Alq3）, bathophenanthroline （Bphen）, bathocuproine, 2,3,8,9,14,15-hexakis-dodecyl-sulfanyl-5,6,11,12,17,18-hexaazatrinaphthylene （HATNA）, and an inorganic compound of Cs2CO3. The influence of the lowest unoccupied molecular orbital level and the electron mobility of organic CBL on the solar cells perfor- mance was compared. The results showed that Alq3, Bphen, and HATNA could significantly improve the device performance. The highest efficiency was obtained from device with an- nealed HATNA as CBL and increased for more than 7 times compared with device without CBL. Furthermore~ the simulation results with space charge-limited current theory indicated that the Schottky barrier at the organic/electrode interface in inverted OSC structure was reduced for 27% by inserting HATNA CBL.展开更多
Grid-connected reactive-load compensation and harmonic control are becoming a central topic as photovoltaic(PV)grid-connected systems diversified.This research aims to produce a high-performance inverter with a fast d...Grid-connected reactive-load compensation and harmonic control are becoming a central topic as photovoltaic(PV)grid-connected systems diversified.This research aims to produce a high-performance inverter with a fast dynamic response for accurate reference tracking and a low total har-monic distortion(THD)even under nonlinear load applications by improving its control scheme.The proposed system is expected to operate in both stand-alone mode and grid-connected mode.In stand-alone mode,the proposed controller supplies power to critical loads,alternatively during grid-connected mode provide excess energy to the utility.A modified variable step incremental conductance(VS-InCond)algorithm is designed to extract maximum power from PV.Whereas the proposed inverter controller is achieved by using a modified PQ theory with double-band hysteresis current controller(PQ-DBHCC)to produce a reference current based on a decomposition of a single-phase load current.The nonlinear rectifier loads often create significant distortion in the output voltage of single-phase inverters,due to excessive current harmonics in the grid.Therefore,the proposed method generates a close-loop reference current for the switching scheme,hence,minimizing the inverter voltage distortion caused by the excessive grid current harmonics.The simulation findings suggest the proposed control technique can effectively yield more than 97%of power conversion efficiency while suppressing the grid current THD by less than 2%and maintaining the unity power factor at the grid side.The efficacy of the proposed controller is simulated using MATLAB/Simulink.展开更多
To solve the multi-variable and multi-objective optimization problem in the thermal design process of the dual-input aeronautic static inverter,an optimization method based on the combination of the multi-objective ev...To solve the multi-variable and multi-objective optimization problem in the thermal design process of the dual-input aeronautic static inverter,an optimization method based on the combination of the multi-objective evolutionary algorithm based on decomposition(MOEA/D)and the fuzzy set theory is proposed.The heat transfer path of the power device is analyzed and an equivalent heat circuit is conducted.We take junction temperature of the power device,mass,and cost of the heat sink as optimization goals,and take the heat sink structure parameters as design variables to conduct thermal optimization based on MOEA/D.This paper carries out a comparative study,and the results show that the proposed improved algorithm can meet the different requirements for multi-objective weights,and have good rapidity and robustness.展开更多
The formation and migration of polarons have important influences on physical and chemical properties of transition metal oxides.Density functional theory plus the Hubbard U correction(DFT+U)and constrained density fu...The formation and migration of polarons have important influences on physical and chemical properties of transition metal oxides.Density functional theory plus the Hubbard U correction(DFT+U)and constrained density functional theory(cDFT)are often used to obtain the transfer properties for small polarons.In this work we have implemented the cDFT plus the Hubbard U correction method in the projector augmented wave(PAW)framework,andapplied it to study polaron transfer in the bulk phases of TiO_(2).We have confirmed that the parameter U can have significant impact on theoretical prediction of polaronic properties.It was found that using the Hubbard U calculated by the cDFT method with the same orbital projection as used in DFT+U,one can obtain theoretical prediction of polaronic properties of rutile and anatase phases of TiO_(2) in good agreement with experiment.This work indicates that the cDFT+U method with consistently evaluated U is a promising first-principles approach to polaronic properties of transition metal oxides without empirical input.展开更多
It is generally cousidered that the mantle creep-flow eurtent is the most important internal cause for erustobody evolution. In fact, the Cause, mantle creep-now current takes place just beneath erustobody. Aeeording ...It is generally cousidered that the mantle creep-flow eurtent is the most important internal cause for erustobody evolution. In fact, the Cause, mantle creep-now current takes place just beneath erustobody. Aeeording to the principle that internal causes of a tning determine its development and evolution, a special attetion should be paid to the basic causea of crustobody evolution. Vnder the guidance of the unbalanced self-organization theory, the authors elueidate that the crustobody system is a far-away thermal balaneed system and an open system, and thete are nonlinear interactions between the essentials, positive feedbacks and frequent fluetuation in the erustobody system. Finally, the following conelusions are drawn: the nonlinear interactions in the erustobody system are the basic formation (main internal cause) for erustobody evolution ; Substance and energy gained from surroundings are the basic conditions (main external cause) of crustobody evolution;and the fluctuations theide the erustobody system are the direct induetive cause of its evolution.展开更多
In this paper, we have proposed the theory of gravity gauge, and the gravity theory has been introduced into quantum field theory. We have further given the tensor equation of gravity field in the flat space, and foun...In this paper, we have proposed the theory of gravity gauge, and the gravity theory has been introduced into quantum field theory. We have further given the tensor equation of gravity field in the flat space, and found the gravity field equation is the Lorentz covariant and gauge invariant. The gravity theory can be quantized and can be unified with the electroweak and strong interaction at a new gauge group .展开更多
In contrast to the solutions of applied mathematics to Zeno’s paradoxes, I focus on the concept of motion and show that, by distinguishing two different forms of motion, Zeno’s apparent paradoxes are not paradoxical...In contrast to the solutions of applied mathematics to Zeno’s paradoxes, I focus on the concept of motion and show that, by distinguishing two different forms of motion, Zeno’s apparent paradoxes are not paradoxical at all. Zeno’s paradoxes indirectly prove that distances are not composed of extensionless points and, in general, that a higher dimension cannot be completely composed of lower ones. Conversely, lower dimensions can be understood as special cases of higher dimensions. To illustrate this approach, I consider Cantor’s only apparent proof that the real numbers are uncountable. However, his widely accepted indirect proof has the disadvantage that it depends on whether there is another way to make the real numbers countable. Cantor rightly assumes that there can be no smallest number between 0 and 1, and therefore no beginning of counting. For this reason he arbitrarily lists the real numbers in order to show with his diagonal method that this list can never be complete. The situation is different if we start with the largest number between 0 and 1 (0.999…) and use the method of an inverted triangle, which can be understood as a special fractal form. Here we can construct a vertical and a horizontal stratification with which it is actually possible to construct all real numbers between 0 and 1 without exception. Each column is infinite, and each number in that column is the starting point of a new triangle, while each row is finite. Even in a simple sine curve, we experience finiteness with respect to the y-axis and infinity with respect to the x-axis. The first parts of this article show that Zeno’s assumptions contradict the concept of motion as such, so it is not surprising that this misconstruction leads to contradictions. In the last part, I discuss Cantor’s diagonal method and explain the method of an inverted triangle that is internally structured like a fractal by repeating this inverted triangle at each column. The consequence is that we encounter two very different methods of counting. Vertically it is continuous, horizontally it is discrete. While Frege, Tarski, Cantor, Gödel and the Vienna Circle tried to derive the higher dimension from the lower, a procedure that always leads to new contradictions and antinomies (Tarski, Russell), I take the opposite approach here, in which I derive the lower dimension from the higher. This perspective seems to fail because Tarski, Russell, Wittgenstein, and especially the Vienna Circle have shown that the completeness of the absolute itself is logically contradictory. For this reason, we agree with Hegel in assuming that we can never fully comprehend the Absolute, but only its particular manifestations—otherwise we would be putting ourselves in the place of the Absolute, or even God. Nevertheless, we can understand the Absolute in its particular expressions, as I will show with the modest example of the triangle proof of the combined horizontal and vertical countability of the real numbers, which I developed in rejection of Cantor’s diagonal proof. .展开更多
文摘Organic solar cells with inverted planar heterojunction structure based on subphthalocya- nine and C60 were fabricated using several kinds of materials as cathode buffer layer （CBL）, including tris-8-hydroxy-quinolinato aluminum （Alq3）, bathophenanthroline （Bphen）, bathocuproine, 2,3,8,9,14,15-hexakis-dodecyl-sulfanyl-5,6,11,12,17,18-hexaazatrinaphthylene （HATNA）, and an inorganic compound of Cs2CO3. The influence of the lowest unoccupied molecular orbital level and the electron mobility of organic CBL on the solar cells perfor- mance was compared. The results showed that Alq3, Bphen, and HATNA could significantly improve the device performance. The highest efficiency was obtained from device with an- nealed HATNA as CBL and increased for more than 7 times compared with device without CBL. Furthermore~ the simulation results with space charge-limited current theory indicated that the Schottky barrier at the organic/electrode interface in inverted OSC structure was reduced for 27% by inserting HATNA CBL.
基金funded by Geran Galakan Penyelidik Muda GGPM-2020-004 Universiti Kebangsaan Malaysia.
文摘Grid-connected reactive-load compensation and harmonic control are becoming a central topic as photovoltaic(PV)grid-connected systems diversified.This research aims to produce a high-performance inverter with a fast dynamic response for accurate reference tracking and a low total har-monic distortion(THD)even under nonlinear load applications by improving its control scheme.The proposed system is expected to operate in both stand-alone mode and grid-connected mode.In stand-alone mode,the proposed controller supplies power to critical loads,alternatively during grid-connected mode provide excess energy to the utility.A modified variable step incremental conductance(VS-InCond)algorithm is designed to extract maximum power from PV.Whereas the proposed inverter controller is achieved by using a modified PQ theory with double-band hysteresis current controller(PQ-DBHCC)to produce a reference current based on a decomposition of a single-phase load current.The nonlinear rectifier loads often create significant distortion in the output voltage of single-phase inverters,due to excessive current harmonics in the grid.Therefore,the proposed method generates a close-loop reference current for the switching scheme,hence,minimizing the inverter voltage distortion caused by the excessive grid current harmonics.The simulation findings suggest the proposed control technique can effectively yield more than 97%of power conversion efficiency while suppressing the grid current THD by less than 2%and maintaining the unity power factor at the grid side.The efficacy of the proposed controller is simulated using MATLAB/Simulink.
基金supported by the National Natural Science Foundation of China(Nos.U1933115,U2133203)
文摘To solve the multi-variable and multi-objective optimization problem in the thermal design process of the dual-input aeronautic static inverter,an optimization method based on the combination of the multi-objective evolutionary algorithm based on decomposition(MOEA/D)and the fuzzy set theory is proposed.The heat transfer path of the power device is analyzed and an equivalent heat circuit is conducted.We take junction temperature of the power device,mass,and cost of the heat sink as optimization goals,and take the heat sink structure parameters as design variables to conduct thermal optimization based on MOEA/D.This paper carries out a comparative study,and the results show that the proposed improved algorithm can meet the different requirements for multi-objective weights,and have good rapidity and robustness.
基金supported by the National Natural Science Foundation of China (No.21873005 and No.21911530231)High-Performance Computing Platform of Peking University
文摘The formation and migration of polarons have important influences on physical and chemical properties of transition metal oxides.Density functional theory plus the Hubbard U correction(DFT+U)and constrained density functional theory(cDFT)are often used to obtain the transfer properties for small polarons.In this work we have implemented the cDFT plus the Hubbard U correction method in the projector augmented wave(PAW)framework,andapplied it to study polaron transfer in the bulk phases of TiO_(2).We have confirmed that the parameter U can have significant impact on theoretical prediction of polaronic properties.It was found that using the Hubbard U calculated by the cDFT method with the same orbital projection as used in DFT+U,one can obtain theoretical prediction of polaronic properties of rutile and anatase phases of TiO_(2) in good agreement with experiment.This work indicates that the cDFT+U method with consistently evaluated U is a promising first-principles approach to polaronic properties of transition metal oxides without empirical input.
文摘It is generally cousidered that the mantle creep-flow eurtent is the most important internal cause for erustobody evolution. In fact, the Cause, mantle creep-now current takes place just beneath erustobody. Aeeording to the principle that internal causes of a tning determine its development and evolution, a special attetion should be paid to the basic causea of crustobody evolution. Vnder the guidance of the unbalanced self-organization theory, the authors elueidate that the crustobody system is a far-away thermal balaneed system and an open system, and thete are nonlinear interactions between the essentials, positive feedbacks and frequent fluetuation in the erustobody system. Finally, the following conelusions are drawn: the nonlinear interactions in the erustobody system are the basic formation (main internal cause) for erustobody evolution ; Substance and energy gained from surroundings are the basic conditions (main external cause) of crustobody evolution;and the fluctuations theide the erustobody system are the direct induetive cause of its evolution.
文摘In this paper, we have proposed the theory of gravity gauge, and the gravity theory has been introduced into quantum field theory. We have further given the tensor equation of gravity field in the flat space, and found the gravity field equation is the Lorentz covariant and gauge invariant. The gravity theory can be quantized and can be unified with the electroweak and strong interaction at a new gauge group .
文摘In contrast to the solutions of applied mathematics to Zeno’s paradoxes, I focus on the concept of motion and show that, by distinguishing two different forms of motion, Zeno’s apparent paradoxes are not paradoxical at all. Zeno’s paradoxes indirectly prove that distances are not composed of extensionless points and, in general, that a higher dimension cannot be completely composed of lower ones. Conversely, lower dimensions can be understood as special cases of higher dimensions. To illustrate this approach, I consider Cantor’s only apparent proof that the real numbers are uncountable. However, his widely accepted indirect proof has the disadvantage that it depends on whether there is another way to make the real numbers countable. Cantor rightly assumes that there can be no smallest number between 0 and 1, and therefore no beginning of counting. For this reason he arbitrarily lists the real numbers in order to show with his diagonal method that this list can never be complete. The situation is different if we start with the largest number between 0 and 1 (0.999…) and use the method of an inverted triangle, which can be understood as a special fractal form. Here we can construct a vertical and a horizontal stratification with which it is actually possible to construct all real numbers between 0 and 1 without exception. Each column is infinite, and each number in that column is the starting point of a new triangle, while each row is finite. Even in a simple sine curve, we experience finiteness with respect to the y-axis and infinity with respect to the x-axis. The first parts of this article show that Zeno’s assumptions contradict the concept of motion as such, so it is not surprising that this misconstruction leads to contradictions. In the last part, I discuss Cantor’s diagonal method and explain the method of an inverted triangle that is internally structured like a fractal by repeating this inverted triangle at each column. The consequence is that we encounter two very different methods of counting. Vertically it is continuous, horizontally it is discrete. While Frege, Tarski, Cantor, Gödel and the Vienna Circle tried to derive the higher dimension from the lower, a procedure that always leads to new contradictions and antinomies (Tarski, Russell), I take the opposite approach here, in which I derive the lower dimension from the higher. This perspective seems to fail because Tarski, Russell, Wittgenstein, and especially the Vienna Circle have shown that the completeness of the absolute itself is logically contradictory. For this reason, we agree with Hegel in assuming that we can never fully comprehend the Absolute, but only its particular manifestations—otherwise we would be putting ourselves in the place of the Absolute, or even God. Nevertheless, we can understand the Absolute in its particular expressions, as I will show with the modest example of the triangle proof of the combined horizontal and vertical countability of the real numbers, which I developed in rejection of Cantor’s diagonal proof. .
