A novel AH-D-A-type phase junction material to improve photovoltaic performance and device stability in fullerene OSCs

In order to boost power conversion efficiency(PCE) and operation stability of organic solar cells(OSCs),we propose a new idea of phase junction materials(PJMs) used as a photoactive layer component to improve device performance and stability.For this purpose,a novel PJM of H-TRC8 based on rhodanine unit was designed with a conjugated AH-D-A framework.Here,AH is a hydrogen-donating electron acceptor unit,D-A is an electron donor-acceptor unit.It is found that H-TRC8 has a good carriertransporting ability,as well as definite hydrogen-bond and D-A interaction with donor/acceptor materials.While H-TRC8 is added into the PBDB-T/PC60BM blend film with 1.0 vol% DIO(1,8-diiodooctane),the resulting blend film exhibited an enhanced absorption and improved morphology.The intermolecular hydrogen bond between H-TRC8 and PBDB-T plays an important role for them,which is confirmed via FT-IR spectra and 2D 1H NMR.As a result,the PBDB-T/PC60BM-based devices with 1.25 wt%H-TRC8 and 1.0 vol% DIO exhibit a significantly improved PCE of 8.06%,which is increased by 20.6% in comparison to that in the binary devices with 1.0 vol% DIO only(PCE=6.68%).Furthermore,the device stability is significantly enhanced with only 43% PCE roll-off at 150℃ for 120 h.This work indicates that AH-D-A-type PJMs are promising photovoltaic materials used as photoactive-layer components to achieve high-performance fullerene OSCs with high device stability.

Regulating Phase Junction and Oxygen Vacancies of TiO_(2) Nanoarrays for Boosted Photoelectrochemical Water Oxidation

In this study,we have provided a facile solution to synthesize well-aligned titanium dioxide nanorods by using hydrothermal reaction.By calcining the materials under different atmospheres and temperatures,a batch of titanium dioxides with excellent oxygen evolution reaction(OER)catalytic efficiency were obtained.This new structured TiO_(2) photoanode material yields a high photocurrent density of 5.69 mA/cm^(2) at 1.23 V vs.reversible hydrogen electrode(RHE)under simulated solar light(100 mW/cm^(2)).Surface photovoltage techniques and other measurements were carried out to confirm that the enhanced photoelectrochemical performances were attributed to the synergistic effect of the phase junction and a certain content of surface states,which accelerate the separation and transmission of the photogenerated charges.This material with phase junction and surface states promises a potential application in the field of photoelectric catalysis under solar light.

Superconducting phase qubits with shadow-evaporated Josephson junctions

We develop a fabrication process for the superconducting phase qubits in which Josephson junctions for both the qubit and superconducting quantum interference device（SQUID） detector are prepared by shadow evaporation with a suspended bridge. Al junctions with areas as small as 0.05 μm^2 are fabricated for the qubit, in which the number of the decoherencecausing two-level systems（TLS） residing in the tunnel barrier and proportional to the junction area are greatly reduced. The measured energy spectrum shows no avoided crossing arising from coherent TLS in the experimentally reachable flux bias range of the phase qubit, which demonstrates the energy relaxation time T1 and dephasing time Tφ on the order of 100 ns and 50 ns, respectively. We discuss several possible origins of decoherence from incoherent or weakly-coupled coherent TLS and further improvements of the qubit performance.

Phase escape of current-biased Josephson junctions

Switching current distributions of an Nb/Al-AlO2/Nb Josephson junction are measured in a temperature range from 25 mK to 800 mK. We analyse the phase escape properties by using the theory of Larkin and Ovchinnikov （LO） which takes discrete energy levels into account. Our results show that the phase escape can be well described by the LO approach for temperatures near and below the crossover from thermal activation to macroscopic quantum tunneling. These results are helpful for further study of macroscopic quantum phenomena in Josephson junctions where discrete energy levels need to be considered.

PHASE-LOCKED 2-D JOSEPHSON JUNCTION ARRAYS AS SUBMILLIMETER OSCILLATORS

This letter presents the results of numerical simulations for phase-locked 2-D Josephson junction array oscillator. The simulation result shows that the junctions of 2-D array can mutually phase-locked in a considerable area if the parameters can be carefully selected. The oscillators are formed with up to 33 identical Nb/AlOx/Nb junctions, and the junctions are connected with Nb microstrip resonators. Optimum structure parameters for oscillator circuit design can be obtained with these simulation results.

Cooper-pair number-phase quantization analysis in double-Josephson-junction mesoscopic circuit coupled by a capacitor

This paper examines the quantization of mesoscopic circuit including Josephson junctions. Following Feynman＇s assumption, via the Hamilton dynamic approach and by virtue of the entangled state representation, it constructs Hamiltonian operator for the double-Josephson-junction mesoscopic circuit coupled by a capacitor. Then it uses the Heisenberg equation of motion to derive the induction voltage across each Josephson junction. The result manifestly shows how the voltage is affected by the capacitance coupling.

Study of 2-Propanol Photocatalytic Degradation on Surface of Phase-Ratio-Controlled TiO_2 Nanoparticles

The crystal form of TiO_2 is a crucial focus of research on the photocatalytic degradation of gaseous pollutants by TiO_2-based composite photocatalysts. To explore the synergistic effect of mixed crystalline TiO_2 on gaseous organic-pollutant photocatalytic degradation, we synthesized a series of TiO_2 nanoparticles with controllable phase ratios. We explored the role of the TiO_2 phase ratio on the photocatalytic activity and degradation pathway in the photodegradation of 2-propanol(IPA). We estimated the crystallite size and crystal proportions of anatase and rutile by X-ray diffraction. We used the Brunauer-Emmett-Teller method to calculate the specific surface area and Fourier transform infrared spectroscopy to characterize the surface chemistry of the samples. Our results show the photocatalytic activities of pure anatase and the sample with 8.6% rutile to be much better than those of the samples with a phase junction and pure rutile. As such, anatase is the better option for the study of photodegradation design and preparation of gas-phase organic pollutants.

微通道内气液两相Taylor流数值模拟

本文采用FLUENT软件对T型微通道内气液两相Taylor流进行模拟,得到了各物理参数对Taylor流的影响规律。在此基础上,采用最小二乘法进行拟合,得到了可以更准确预测T型通道内气液两相Taylor流气泡和液柱长度的经验关联式。

On the Bosonic Phase Operator Realization for Josephson Hamiltonian Model

On the assumption that a Cooper pair acts as a Bose particle and based on the newly established <η|representation, which is the common eigenvector of two particles' relative position and total momentum, we introduce a mesoscopic Josephson junction Hamiltonian constituted by two-mode Bose phase operator and number-difference operator. The number-difference-phase uncertainty relation can then be set up, which implies the existence of Josephson current.

Number-Phase Quantization Scheme for L-C Circuit

For a mesoscopic L-C circuit,besides the Louisell's quantization scheme in which electric charge q andelectric current I are respectively quantized as the coordinate operator Q and momentum operator P,in this paperwe propose a new quantization scheme in the context of number-phase quantization through the standard Lagrangianformalism.The comparison between this number-phase quantization with the Josephson junction's Cooper pair number-phase-difference quantization scheme is made.

Magnetic field induced phase branches of the superconducting transition in two-dimensional square π-loop arrays

Based on the results of explicit forms of free energy density for each possible arrangement of magnetization fluxes in large-scale two-dimensional （2D） square π-loop arrays given by Li et al [2007 Chin. Phys. 16 1450], the field-cooled superconducting phase transition is further investigated by analysing the free energy of the arrays with a simplified symmetrical model. Our analytical result is exactly the same as that obtained in Li＇s paper by means of numerical calculations. It is shown that the phase transition splits into two branches with either ferromagnetic or anti-ferromagnetic flux ordering, which depends periodically on the strength of external magnetic flux φe through each loop and monotonically on the screen parameter β of the loops in the arrays. In principle, the diagram of the phase branches is similar to that of its one-dimensional counterpart. The influence of thermal fluctuation on the flux ordering during the transition from normal to superconducting states of the π-loop arrays is also discussed.

Traffic Flow Merging and Bifurcating at Junction on Two-Lane Highway

In this paper we study the traffic states and jams in vehicular traffic merging and bifurcating at a junction on a two-lane highway. The two-lane traffic model for the vehicular motion at the junction is presented where a jam occurs frequently due to merging, lane changing, and bifurcating. The traffic flow is called the weaving. At the weaving section, vehicles slow down and then move aside on the other lane for changing their direction. We derive the fundamental diagrams (flow-density diagrams) for the weaving traffic flow. The traffic states vary with the density, slowdown speed, and the fraction of vehicles changing the lane. The dynamical phase transitions occur. It is shown that the fundamental diagrams depend highly on the traffic states.

转角铜氧化物中的约瑟夫森效应

当前常压下超导转变温度最高的材料仍然来自铜氧化物家族.然而,铜氧化物超导的微观机理仍未被完全建立起来,成为了凝聚态物理领域最具挑战性的问题之一.测定配对波函数的相位部分是全面理解高温超导机理不可或缺的一环.该实验往往需要将不同晶向的铜氧化物拼接成高质量的约瑟夫森结,十分考验样品的合成制备技术.近年来,利用二维材料中发展起来的范德瓦耳斯堆垛技术,研究者们构建了具有原子级平整界面的转角铜氧化物双晶结,研究了不同掺杂浓度、不同转角下的约瑟夫森隧穿,探索了其中出现s波、d波、以及由于界面耦合演生出的d+id波配对的可能性.本文将回顾转角铜氧化物约瑟夫森结的研究进展,介绍近年来发展起来的转角结制备技术,讨论当前实验测量的结果及其意义,提出尚待解决的关键性问题.

A Study of Power Loss for 3 Phase Voltage Source Converter of Elevator

In this paper,to study the power loss of converter for elevator,The analysis is to establish relationship between parameters(current,voltages and losses in the inverter and converter) relevant for sizing of major components of the drive was done.) For high PWM(pulse width modulation) frequency like in elevator applications of fpwm =10kHz,switching losses are dominant and are about 2/3 of the total losses on IGBT switch.Transition from continuous 3 phase to discontinuous 2 phase PWM results in 50% reduction of switching loses on IGBT devices providing that PWM is not done over 60deg angle in a particular phase when current has maximum value.Total losses on IGBT(conduction + switching) are reduced approximately by ～1/3 what is still a significant reduction.Two phase PWM with reduced losses can be used for applications when acoustic noise due to increased current ripple is not significant and fall back solution to regular 3 phase PWM when drive operates under rare extreme conditions resulting in increased heat sink temperature.The analysis will be examined by further laboratory testing simulating 60% duty cycle on a dynamometer.

h-WO_(3)/m-WO_(3)异相结的制备及其在含油污水处理中的应用

本文采用一步水热法,通过改变NaCl添加量,成功制备了h-WO_(3)/m-WO_(3)异相结型光催化剂。利用XRD、Raman、SEM、BET等方法对h-WO_(3)/m-WO_(3)异相结样品的结构形貌进行表征,通过能带结构分析和光生载流子分离效率分析证明这种异相结型光催化剂能够促进光生载流子的分离效率。在光催化去除含油污水TOC实验中,h-WO_(3)/m-WO_(3)异相结光催化剂在2 h光照内含油污水的TOC去除率达到了93.8%,按一级反应动力学模型拟合后得到其反应动力学常数为0.0234 min^(-1),分别为纯m-WO_(3)和纯h-WO_(3)样品的4.0和6.2倍。

WO_3中单斜相/六方相异相结的构建及提高光催化降解罗丹明B活性（英文）

光催化技术被认为有可能成为解决环境污染和能源危机的有效手段之一,引起了各国政府和科学家的极大兴趣.以TiO_2,WO_3和Bi_2O_3等半导体为催化剂的光催化反应受到广泛关注.WO_3是一种典型的n型半导体材料,具有电致变色、气敏和光催化等性能,在电致变色器件、气敏传感器和光催化剂等方面有着广泛应用前景.由于WO_3具有高的太阳能利用率、良好的可见光响应性和较强的抗光腐蚀性,是一种极具开发潜力的半导体光催化材料,所以在光解水制氢及催化降解有机污染物等领域中得到广泛应用.然而,WO_3半导体表面上较高的光生电子-空穴复合效率是影响其光催化性能的主要因素之一,从而限制了WO_3在光催化领域的工业应用.研究发现,TiO_2材料在从锐钛矿向金红石转变的过程中,通过精细调变焙烧温度,可以在两种晶相的界面形成TiO_2异相结.形成的锐钛矿-金红石异相结能有效促进电子-空穴分离.目前,构建异相结已成为改善光催化剂电子-空穴分离效率的有效方法之一.近年来,人们先后成功构建了a-Ga_2O_3/b-Ga_2O_3,a-Bi_2O_3/b-Bi_2O_3和WO_3/WO_3·H_2O等异相结,这些异相结催化剂在光催化降解水产氢和降解污染物反应中显示了比单一晶相更高的光催化活性.WO_3是一种多晶相材料,具有正交、六方、单斜和四方等多种晶体结构,其中六方晶相(h-WO_3)由于具有开放结构而在气体传感器和电池电极等领域显示了突出性能,而单斜晶相(m-WO_3)具有合适的带宽和良好的可见光响应性,因而广泛应用在光催化领域.而且,h-WO_3的导带和价带均低于m-WO_3的导带和价带,所以在WO_3材料中有可能通过构建单斜/六方异相结(m-WO_3/h-WO_3)来提高WO_3的光催化性能.本文借鉴半导体异相结概念,采用固相热分解法,试图通过调节焙烧温度和焙烧时间以构建m-WO_3/h-WO_3异相结催化剂.利用X射线衍射(XRD)、高分辨透射电镜(HRTEM)、扫描电镜(SEM)、X射线光电子能谱仪(XPS)和N_2吸附-脱附等方法对WO_3样品的晶相结构、形貌和元素组成等进行了表征.以光催化降解罗丹明B(RhB)为模型,研究了不同晶相WO_3材料的光催化性能,考察了WO_3晶相和异相结对其光催化性能的影响,从而为WO_3材料中异相结的构建提供思路、方法和理论指导.结果表明,采用偏钨酸铵固相热分解制备WO_3的过程中,焙烧温度为600–700℃时,样品为单斜晶相,随着焙烧温度升高至800℃时,样品中开始出现六方晶相.随着焙烧温度升高,h-WO_3的含量没有明显变化,当温度升至1000℃时,h-WO_3的含量有所减少.SEM和HRTEM结果验证了m-WO_3/h-WO_3异相结的形成,小的m-WO_3粒子分布在棒状h-WO_3上,并且两者紧密接触.为了进一步证实WO_3的异相结效应,将偏钨酸铵在800℃焙烧不同时间(8–30 h).结果表明,通过改变焙烧时间可有效控制m-WO_3和h-WO_3混合晶相比例,800℃焙烧8 h时m-WO_3为主要晶相,焙烧12 h时h-WO_3含量明显增加,当焙烧时间延长至24和30 h时h-WO_3含量减少.SEM结果同样显示,在800℃焙烧12 h样品中棒状h-WO_3显著增多,与小的m-WO_3粒子接触几率增大,即m-WO_3/h-WO_3异相结数量增加.不同晶相WO_3样品光催化降解RhB的结果表明,具有m-WO_3/h-WO_3异相结结构的WO_3催化剂具有较高光催化活性.荧光光谱结果表明,单斜相/六方相异相结的形成提高了电子-空穴分离效率,从而提高了其光催化降解Rh B的活性.而在具有m-WO_3/h-WO_3异相结结构的WO_3催化剂中,随着焙烧温度升高或焙烧时间延长,h-WO_3含量有所减少,从而导致暴露的m-WO_3/h-WO_3异相结数量减少,因而使得活性有所降低.本文采用固相热分解法通过调变焙烧温度构建了m-WO_3/h-WO_3异相结光催化剂,显著提高了光催化降解RhB的活性,这对设计合成高效WO_3基光催化剂具有一定借鉴.

不等径水平三通的相分离特性研究

在空气-水两相流实验回路上对油田注汽管线上的一种不等径水平三通进行了相分离特性实验研究。结果表明,侧支管的出口干度X3并非始终高于主管进口干度,当分流比超过某一临界值时X3将低于主管入口干度。该临界值随入口气相折算流速的提高而增大,同时通过在三通上游布置挡板也显著提高了临界分流比,证明流体惯性是影响水平三通相分离特性的最主要因素。与等径三通相比,不等径三通的特性曲线随着侧支管相对内径的缩小逐渐向左下方移动。

水流交汇区的水动力学特性数值模拟

为开展水流交汇区污染物浓度分布研究,进行水流交汇区水动力学特性的数值模拟,建立适用于水流交汇区的水气两相流数学模型。模型采用Weber试验数据进行验证,验证结果表明模型模拟的自由水面、流场与试验结果吻合较好。针对交汇区浓度分布试验的研究需要,模拟分析了不同交汇角、流量比和动量比对交汇区水动力学特性的影响。研究结果表明:分离区的范围随交汇角、流量比和动量比的减小而逐渐缩小直至分离区消失,交汇角、流量比和动量比越小,交汇口上游水位的壅高及分离区内水位的下降程度越不明显。

利用T型三通测量气液两相流体的流量和干度

利用T型三通的相分离特性 ,从被测气液两相流体中分流分离出一部分单相气体 ,通过测量这部分单相气体的流量确定被测气液两相流体的流量或干度。这种方法把两相流体的流量测量转化成了单相流的测量 ,测量仪表的稳定性和可靠性能得到显著改善 ,测量精度得以大幅度提高。试验结果证实 ,分流系数与被测两相流的干度成正比。在本文实验范围内 ,流量和干度的平均测量误差小于± 5 %。