Spontaneously coherent orbital coupling of counterrotating exciton polaritons in annular perovskite microcavities

Exciton-polariton condensation is regarded as a spontaneous macroscopic quantum phenomenon with phase ordering and collective coherence.By engineering artificial annular potential landscapes in halide perovskite semiconductor microcavities,we experimentally and theoretically demonstrate the room-temperature spontaneous formation of a coherent superposition of exciton-polariton orbital states with symmetric petal-shaped patterns in real space,resulting from symmetry breaking due to the anisotropic effective potential of the birefringent perovskite crystals.The lobe numbers of such petal-shaped polariton condensates can be precisely controlled by tuning the annular potential geometry.These petal-shaped condensates form in multiple orbital states,carrying locked alternating nphase shifts and vortex-anti vortex superposition cores,arising from the coupling of counterrotating exciton-polaritons in the confined circular waveguide.Our geometrically patterned microcavity exhibits promise for realizing room-temperature topological polaritonic devices and optical polaritonic switches based on periodic annular potentials.     

The role of exciton and charge carrier diffusion in photoenhancedcurrents

This work concerns the influence on photoenhanced currents of the diffusion of excitons as well as of charge carriers. It is shown that both kinds of diffusion are important for photoenhanced currents in the case of thin samples. Experimental results obtained on tetracene layers confirm this conclusion     

Drastic transitions of excited state and coupling regime in all-inorganic perovskite microcavities characterized by exciton/plasmon hybrid natures

Lead-halide perovskites are highly promising for various optoelectronic applications,including laser devices.However,fundamental photophysics explaining the coherent-light emission from this material system is so intricate and often the subject of debate.Here,we systematically investigate photoluminescence properties of all-inorganic perovskite microcavity at room temperature and discuss the excited state and the light–matter coupling regime depending on excitation density.Angle-resolved photoluminescence clearly exhibits that the microcavity system shows a transition from weak coupling regime to strong coupling regime,revealing the increase in correlated electron–hole pairs.With pumping fluence above the threshold,the photoluminescence signal shows a lasing behavior with bosonic condensation characteristics,accompanied by long-range phase coherence.The excitation density required for the lasing behavior,however,is found to exceed the Mott density,excluding the exciton as the excited state.These results demonstrate that the polaritonic Bardeen–Cooper–Schrieffer state originates the strong coupling formation and the lasing behavior.     

Quantification of electron accumulation at grain boundaries in perovskite polycrystalline films by correlative infrared-spectroscopic nanoimaging and Kelvin probe force microscopy

Organic–inorganic halide perovskites are emerging materials for photovoltaic applications with certified power conversion efficiencies (PCEs) over 25％. Generall...     

KEELOQ滚动加密技术在汽车防盗系统中的应用

KEELOQ滚动加密技术作为Microchip公司的一项专利产品被广泛应用于各安防领域.在汽车防盗系统中汽车中控锁是一个必不可少的部分,其保密性设计在汽车防盗系统中高于任何其他的防盗装备.KEELOQ加密技术较之其他加密技术增加了同步计数值参与加密,每次发送数据时,同步计数器的值都得到更新,从而加密结果在每次发送数据时都得到改变,这种技术被称为滚动加密技术,具有很好的抗截获性.本文讨论了KEELOQ加密技术在汽车防盗报警系统中的应用,详细介绍了KEELOQ加密机制的原理,利用HSC301实现硬件加密和用软件实现解密的方法.     

跳频检测中快速测频系统的设计

由于单片机受本身时钟频率和若干指令运算的限制,若单独使用它来开发测频系统,测频速度较慢,无法满足跳频检测设备中高速测频的需求.为满足跳频通信中测频应变速度快、灵敏度高的要求,本文将介绍一种以FPGA为测频核心处理芯片、单片机(C8051F020)为数据处理器的高速测频系统的设计方法,并详细地介绍了系统的组成, FPGA的设计、功能仿真等.实验结果表明,该方案完全符合设计要求.     

Influence of rapid thermal annealing on pyrochlore/perovskite phase formation in laser ablated Pb(Zr,Ti)O3 thin films

Abstract

Pb(Zr,Ti)O₃ thin films were prepared by ArF excimer laser deposition on silicon and Pt-coated silicon substrates, and then were treated by rapid thermal annealing. The dependence of perovskite/pyrochlore phase formation on annealing conditions was investigated. The results show that the formation of perovskite phase or pyrochlore phase in the films was not only dependent on the heat treatment temperature, but also dependent on the heat treatment time. A wide range operational window of heat treatment time and temperature for obtaining single phase perovskite Pb(Zr,Ti)O₃ thin films was given, and the films were analyzed by Rutherford backscattering spectroscopy to explain this phase transition.     

光照发电厂轴瓦温度跳变的原因分析及处理

机组轴承的测温电阻质量参差不齐,不能满足运行要求。测温电阻电缆长期浸泡在导轴承、推力轴承油槽里,使电缆外皮变硬变脆,很难弯折。电缆表面出现很多裂纹,长期受高温油流的冲击,造成运行中测温电阻电缆断裂。机组长时间运行在振动区．造成测温回路端子松动。电缆与测温电阻端部出现虚焊。     

从世界首座废旧家电再利用工厂投入试运行谈起

１前言世界上提倡资源循环并采取有力行动的国家首推日本。除在东京近郊和琦玉县已建成五层楼的“生态公寓”样板房，供居民使用以后要在全国推广外，现在东芝公司和别的企业合作又建成世界首座包括电视机、电冰箱、空调器及电脑在内的五种废旧家电再利用工厂，并投入试验...     

Modeling of complex oxide materials from the first principles: systematic applications to vanadates RVO3 with distorted perovskite structure

??Realistic modeling?? is a new direction of electronic structure calculations, where the main emphasis is made on the construction of some effective low-energy model entirely within a first-principle framework. Ideally, it is a model in form, but with all the parameters derived rigorously, on the basis of first-principles electronic structure calculations. The method is especially suit for transition-metal oxides and other strongly correlated systems, whose electronic and magnetic properties are predetermined by the behavior of some limited number of states located near the Fermi level. After reviewing general ideas of realistic modeling, we will illustrate abilities of this approach on the wide series of vanadates RVO₃ (R=La, Ce, Pr, Nd, Sm, Gd, Tb, Yb, and Y) with distorted perovskite structure. Particular attention will be paid to computational tools, which can be used for microscopic analysis of different spin and orbital states in the partially filled t _2g -band. We will explicitly show how the lifting of the orbital degeneracy by the monoclinic distortion stabilizes C-type antiferromagnetic (AFM) state, which can be further transformed to the G-type AFM state by changing the crystal distortion from monoclinic to orthorhombic one. Two microscopic mechanisms of such a stabilization, associated with the one-electron crystal field and electron correlation interactions, are discussed. The flexibility of the orbital degrees of freedom is analyzed in terms of the magnetic-state dependence of interatomic magnetic interactions.     

Higher-order modelling of the diffusion dynamics in a bipolar transistor

A higher-order diffusion model for a bipolar transistor has been developed. This model is based on the Padé approximation of the quasi-static expansions of the base and collector currents and gives improved accuracy for the simulation of fast transients and periodic operation at high frequencies. the effect of higher-order circuit elements on accuracy is demonstrated by calculating the transient response to a step excitation and by determining the scattering parameters of a transistor model with higher-order elements linearized about an operating point. the higher-order model is replaced by an equivalent circuit including only conventional elements, and the transient behaviour of these two models is compared.     

严寒地区发电厂冷却水余热回收系统的效益分析

搭建了电厂冷却水余热回收与利用实验台,通过实验对电厂冷却水余热回收与利用系统的供热效果进行分析。通过实验数据并结合长春热电一厂的实际运行情况对该系统进行了环保效益分析。利用费用年值法将此种供热方式与其他几种供热方式进行比较,提出了供热方式的选择原则,为严寒地区今后实际工程应用提供了参照数据。     

Effects of restricted diffusion in a biological phantom: a q-space diffusion MRI study of asparagus stems at a 3T clinical scanner

Introduction The aim of this work was to study the effects of restricted diffusion in a biological phantom consisting of green asparagus stems using q-space MRI at a clinical scanner. Method Measurements of the full width at half maximum (FWHM) of the displacement distribution were performed with varied diffusion time (T _d). The accuracy of the measurements was investigated with respect to the degree of violation of the short gradient pulse (SGP) condition, partial volume effects and a FWHM-based tensor model. Results The measurements showed a reasonably constant FWHM perpendicular to the capillaries in the vascular bundles and an increased FWHM parallel with the bundles when the T _d was increased. A 15% decrease in FWHM perpendicular to the bundles was observed when the diffusion encoding duration was prolonged from 24 to 74 ms, owing to the violation of the SGP condition. For a population of different confinement sizes, simulations indicated that the FWHM reflects the smaller sizes rather then the mean size of the confinements. Conclusion A new method allowing tensor analysis of FWHM was derived and yielded accurate results. In conclusion, we found it possible to measure the effects of restricted diffusion with q-space MRI using a clinical MRI scanner.     

Influence of the calcium excess in the structural and spectroscopic properties of the complex perovskite Ba3CaNb2O9

The effects of the change in the Ca/Nb ratio in the structure and spectroscopic properties of the solid solution Ba₃Ca_1+xNb_2-xO_9-δ with x?=?0–0.25 are investigated. The solid solution undergoes a transition from an hexagonal phase (2:1 order) to a cubic phase (1:1 order) with increasing calcium content as indicated by X-Ray diffraction and Raman. The calcium excess matches with a gradual increase in blue colour due to a reduction at the high temperatures of sintering. Optical absorption experiments showed that there are different absorption bands in the region 0.45–4.5?eV corresponding tentatively to OH vibrations, polarons and monovalent oxygen vacancies. The series properties change gradually with calcium excess with the exception of Ba₃Ca_1.18Nb_1.82O_9-δ that showed a slight change attributable to the presence of protons in the lattice. These changes can be used to quantify protons in complex perovskites.     

绿色清洗技术在电厂灰场回水管道中的应用

大庆石化公司热电厂应用空穴射流技术,解决了灰场回水管道结垢难题。介绍该技术的工作原理和使用条件,并说明了实施情况:将预先设计好的清洗器投入管道内,以压力水作为动力推进清洗器,通过电子定位仪观测清洗器的运动状态。如清洗器遇到卡阻,通过电子定位仪可迅速确定位置,并排除故障,直到清洗器行进到接收装置。总结了在清洗过程中遇到的问题和解决办法。应用结果表明,清洗后2条回水管线残留垢厚不超过2mm,管线的防腐涂层完好,灰场回水管线流量达到了预期要求。     

Recent advances in the deposition of ferroelectric thin films

Abstract

Recent developments in ferroelectric thin film deposition involving plasma based approaches, are described, which include a) multi-magnetron sputter deposition, b) Multi-ion-beam reactive sputter (MIBERS) deposition, c) Pulsed excimer laser ablation and d) ECR (Electron cyclotron resonance) plasma assisted deposition. These methods commonly prevailed intrinsic low energy ion bombardment during the growth process, which may be used for the control over composition, crystallization temperature and microstructure. A low energy (60–75 eV) ion bombardment of the ferroelectric Pb(Zr, Ti)O₃ thin films indicated a reduction in the phase formation/crystallization temperature, improved the electrical properties, microstructure and the surface smoothness. Discussion is presented exphasizing the effects of low energy bombardment in different deposition processes. Recent findings using rapid thermal annealing process are also described.     

Electrochemical strain microscopy of local electrochemical processes in solids: mechanism of imaging and spectroscopy in the diffusion limit

Changes in ionic concentration and electrochemical processes in solids are invariably associated with changes in molar volume. Correspondingly, materials with mobile ions develop strain in response to applied electric bias. This electromechanical coupling mediated by mobile ions lays the foundation for the electrochemical strain microscopy (ESM) of energy storage and conversion materials. Here, we analyze the imaging and spectroscopic mechanism in ESM in the diffusion limit and discuss the similarities between ESM and macroscopic current-based electrochemical measurements. The theoretical challenges in ESM are formulated.     

Identification of variegated coloring in skin tumors: neuralnetwork vs. rule-based induction methods

The use of neural networks for automatic identification of variegated coloring, which is believed to be one of the most predictive features for malignant melanoma, is described. The Nestor development system (NDS) was chosen for neural network implementation. At the heart of NDS is a three-layer neural network called a restricted Coulomb energy (RCE) network. The learning scheme and the database for detection of variegated coloring are discussed. Results are reported     

The effect of diffusion gradient direction number on corticospinal tractography in the human brain: an along-tract analysis

Objectives

We evaluated diffusion imaging measures of the corticospinal tract obtained with a probabilistic tractography algorithm applied to data of two acquisition protocols based on different numbers of diffusion gradient directions (NDGDs).

Materials and methods

The corticospinal tracts (CST) of 18 healthy subjects were delineated using 22 and 66-NDGD data. An along-tract analysis of diffusion metrics was performed to detect possible local differences due to NDGD.

Results

FA values at 22-NDGD showed an increase along the central portion of the CST. The mean of partial volume fraction of the orientation of the second fiber (f2) was higher at 66-NDGD bilaterally, because for 66-NDGD data the algorithm more readily detects dominant fiber directions beyond the first, thus the increase in FA at 22-NDGD is due to a substantially reduced detection of crossing fiber volume. However, the good spatial correlation between the tracts drawn at 22 and 66 NDGD shows that the extent of the tract can be successfully defined even at lower NDGD.

Conclusions

Given the spatial tract localization obtained even at 22-NDGD, local analysis of CST can be performed using a NDGD compatible with clinical protocols. The probabilistic approach was particularly powerful in evaluating crossing fibers when present.

     

Development of methods for the decrease in instability of recycling water of conjugated closed-circuit cooling system of HPP

On Russian HPPs, conjugated closed-circuit cooling systems, where purge water is used as initial for water-treatment facilities, are widespread. For this reason, it is impossible to use general methods for the stabilization treatment of recycling water in order to prevent scale formation in the units of a system, namely, turbine condensers and cooling towers. In this paper, the methods for the decrease in the instability of recycling water using the methods of chemical engineering, such as stabilization and synchronization of flows and organization of recycles, are suggested. The results of an industrial experiment on the implementation of stabilization treatment of recycling water by the organization of recycle are given. The experiment was carried out on Kazan CHPP-3. The flow scheme involved the recycle of chemically purified water (CPW) for the heat network make-up to the closed-circuit cooling system. The experiment was carried out at three stages with the gradual change of the consumption of the recycle, namely, 0, 50, and 100 t/h. According to the results of experiments, the reliable decrease in the rate of the sedimentation was recorded on the units of the system, namely, turbine condenser and chimney-type cooling tower. This is caused by two reasons. Firstly, this is periodic excessive concentration of recycling water due to the nonstationary character of inlet and outlet flows. Secondly, this is seasonal (particularly, in the summer period) exceeding of the evaporation coefficient. As a result of stabilization and synchronization of flows and organization of recycles, the quality of clarified and chemically purified water for the heat network make-up increases and the corrosion of iron- and copper-containing structural materials decreases. A natural decrease in temperature drop on the operating turbine condensers is mentioned.