CHARACTERISTICS OF DROPLET TRANSFER IN CO_2 LASER-MIG HYBRID WELDING WITH SHORTCIRCUITING MODE

LF6 aluminum alloy plates with 4.5 mm thickness are welded in this experiment. Welding is carried out by using the CO2 laser-MIG paraxial hybrid welding in fiat position. The experimental results indicate that the inherent droplet transfer cycle time of conventional MIG arc is changed due to the interaction between CO2 laser beam and MIG arc in the short-circuiting mode of laser-MIG hybrid welding. Because of the preheating action of CO2 laser to electrode and base material, the droplet transfer frequency of MIG arc is increased in the hybrid welding process. When laser power is increased to a certain degree, the droplet transfer frequency is decreased due to the effect of laser-induced keyhole. Furthermore, through analyzing the MIG welding current and arc voltage waveforms and the characteristics of droplet transfer in the hybrid welding process, the effect of laser energy and the action point between laser beam and arc on the frequency of droplet transfer and weld appearance is investigated in details.

Band Edge Emission Improvement by Energy Transfer in HybridⅢ-Nitride/Organic Semiconductor Nanostructure

GaN nanorods are fabricated using inductively coupled plasma etching with Ni nano-island masks. The poly [2- methoxy-5-（2-ethyl）hexoxy-l,4-phenylenevinylene] （MEH-PPV）/GaN-nanorod hybrid structure is fabricated by depositing the MEH-PPV film on the GaN nanorods by using the spin-coating process. In the hybrid structure, the spatial separation is minimized to achieve high-emciency non-radiative resonant energy transfer. Optical properties of a novel device consisting of MEH-PPV/GaN-nanorod hybrid structure is studied by analyzing photoluminescenee （PL） spectra. Compared with the pure GaN nanorods, the PL intensity of the band edge emission of GaN in the MEH-PPV/GaN-nanorods is enhanced as much as three times, and the intensity of the yellow band is suppressed slightly. The obtained results are analyzed by energy transfer between the GaN nanorods and the MEH-PPV. An energy transfer model is proposed to explain the phenomenon.

Quantum state transfer via a hybrid solid–optomechanical interface

We propose a scheme to implement quantum state transfer between two distant quantum nodes via a hybrid solid–optomechanical interface. The quantum state is encoded on the native superconducting qubit, and transferred to the microwave photon, then the optical photon successively, which afterwards is transmitted to the remote node by cavity leaking,and finally the quantum state is transferred to the remote superconducting qubit. The high efficiency of the state transfer is achieved by controllable Gaussian pulses sequence and numerically demonstrated with theoretically feasible parameters.Our scheme has the potential to implement unified quantum computing–communication–computing, and high fidelity of the microwave–optics–microwave transfer process of the quantum state.

High-Performance Sodium Bose-Einstein Condensate Apparatus with a Hybrid Trap and Long-Distance Magnetic Transfer

We report on the production of large sodium Bose^Einstein condensates in a hybrid of magnetic quadrupole and optical dipole trap. With an optimized spin-flip Zeeman slower, 2 ~ 1010 sodium atoms are captured in the magneto-optical trap （MOT）. A long distance magnetic transfer setup moves the cold atom over 46cm from the MOT chamber to the UHV science chamber, which provides great optical access and long conservative trap lifetime. After evaporative cooling in the hybrid trap, we produce nearly pure condensates of 1 ~ 107 atoms with lifetime of 80 s in the optical dipole trap.

Scalable Quantum Information Transfer between Individual Nitrogen-Vacancy Centers by a Hybrid Quantum Interface

We develop a design of a hybrid quantum interface for quantum information transfer （QIT）, adopting a nanome- chanical resonator as the intermedium, which is magnetically coupled with individual nitrogen-vacancy centers as the solid qubits, while eapacitively coupled with a coplanar waveguide resonator as the quantum data bus. We describe the Hamiltonian of the model, and analytically demonstrate the QIT for both the resonant interaction and large detuning cases. The hybrid quantum interface allows for QIT between arbitrarily selected individual nitrogen-vacancy centers, and has advantages of the sealability and controllability. Our methods open an alter- native perspective for implementing QIT, which is important during quantum storing or processing procedures in quantum computing.

Effect of laser power on metal transfer in laser-double arcs P-MAG hybrid welding with single power source

The effect of laser power on metal transfer is studied under conditions of alternating combustion of double arcs in order to develop the welding process of the laser-double arcs pulsed metal active gas （P-MAG） hybrid welding with single power. Different laser power corresponds to different interactive mechanisms of laser and arc and to different methods of metal transfer in the hybrid welding. When the laser power ascends from 500 W to 1 500 W, the methods of metal transfer change from the complex transfer of one droplet per pulse, one droplet two pulses and one droplet much more pulses during the mixture of globular and projected transfer of the lead wire, and from one droplet two pulses and one droplet three pulses during globular transfer of the follow wire to the methods of the metal transfer of both lead wire and follow wire are stable one droplet two pulses and one droplet three pulses when the metal transfer is mainly globular. The arc sharps and pressure of droplet are altered with the laser power changing. The compression of the arcs is strengthened by the laser and the offset of the center of droplet mass is much more obvious with the increasing of the laser power.

Hybrid手术对颈椎力传导方式的影响

目的研究人工椎间盘置换（total disc replacement,TDR）合并融合的Hybrid手术后颈椎的力传导模式,从生物力学角度加深对Hybrid手术的认识。方法建立正常颈椎有限元模型（INTACT模型）,模拟C4~6节段退变的3种手术方案：上置换＋下融合（TDR45模型）、上融合＋下置换（TDR56模型）、双节段融合（Fusion456模型）。结果所有手术模型中,融合节段的活动能力完全丧失,置换节段的活动能力有所增加。在160 N轴向力作用下,INTACT模型整个节段后伸4°,而TDR45与TDR56模型的颈椎节段分别后伸8.2°与8.9°。在TDR56模型中,经过C5椎体的力减少20%,经过置换节段小关节的力增加3.8倍。在TDR45模型中,经过置换节段小关节的力增加50%。INTACT模型的最大关节应力为0.8 MPa,而TDR45与TDR56模型置换节段的小关节应力均高达正常颈椎的2倍。结论由于置换节段活动范围的增加,Hybrid术后颈椎曲度在轴向力作用下发生较大改变（后伸）。这种改变将导致经过置换节段椎体的力有所减少,而经过小关节的力有所增加,从而增加置换节段小关节的应力。

Quantum information transfer between topological and conventional charge qubits

We propose a scheme to realize coherent quantum information transfer between topological and conventional charge qubits. We first consider a hybrid system where a quantum dot（QD） is tunnel-coupled to a semiconductor Majorana-hosted nanowire（MNW） via using gated control as a switch, the information encoded in the superposition state of electron empty and occupied state can be transferred to each other through choosing the proper interaction time to make measurements.Then we consider another system including a double QDs and a pair of parallel MNWs, it is shown that the entanglement information transfer can be realized between the two kinds of systems. We also realize long distance quantum information transfer between two quantum dots separated by an MNW, by making use of the nonlocal fermionic level formed with the pared Majorana feimions（MFs） emerging at the two ends of the MNW. Furthermore, we analyze the teleportationlike electron transfer phenomenon predicted by Tewari et al. [Phys. Rev. Lett. 100, 027001（2008）] in our considered system.Interestingly, we find that this phenomenon exactly corresponds to the case that the information encoded in one QD just returns back to its original place during the dynamical evolution of the combined system from the perspective of quantum state transfer.

SYNTHESIS OF HYBRID MESOPOROUS POLYSTYRENE-SILICA MATERIALS WITH NON-SURFACTANT CITRIC ACID AS TEMPLATE VIA SOL-GEL PROCESS

Hybrid mesoporous polystyrene-silica materials were successfully prepared through HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and triethoxysilyl-functionalized polystyrene obtained via atom transfer radical polymerization (ATRP) of styrene, in the presence of citric acid (CA) as non-surfactant template or pore-forming agent and followed by ethanol extraction to remove template molecules. The materials were characterized by infrared spectroscopy OR), N-2 adsorption-desorption measurements, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The results indicate that the materials prepared with 50 wt%-60 wt% template contents have average pore sizes of 2-3 nm and large surface areas (ca. 886 m(2)/g) as well as high pore volumes (ca. 0.53 cm(3)/g). The mesoporosity arises from interconnected channels and pores with disordered arrangements. The pore diameters and pore volumes increase as the template content is increased. The pore diameters show a little change upon heating at 200degreesC overnight. However, the materials do not have good hydrothermal stability.

Theoretical Investigation of Nonlinear Optical Properties of Organicand Transition Metal Hybrid Azobenzene Dendrimers

In this work, we report a theoretical exploration of the responses of organic azobenzene dendrimers. The polarizabilities, the first and second hyperpolarizabilities of the azobenzene monomers （GO）, and the first, second and third generation （G1, G2 and G3, respectively） are investigated by semi-empirical methods. The calculated results show that the nonlinear optical （NLO） properties of these organic dendrimers are mainly determined by the azobenzene chromospheres. Additionally, the values oft and y increase almost in proportion to the number of chromophores. On the other hand, two types of transition metal hybrid azobenzene dendrimers （core-hybrid and branch-end hybrid according to the sites combined with transition metals） are simulated and discussed in detail in the framework of time-dependent density functional theory （TDDFT）. The calculated results reveal that the NLO responses of these metal dendrimers distinctly varied as a result of altering the charge transfer transition scale and the excitation energies.

A Simple Closed Form Solution to Single Layer Heat Spreading Angle Appropriate for Microwave Hybrid Modules

A simple equation for heat spreading angle is derived which is useful for cases with a single layer thermal spreader. The derivation starts with Fourier’s heat transfer law. Heat spreading in two dimensions is then introduced which results in a quadratic equation relative to spreading angle. The result is a closed form equation for heat spreading angle. Calculations using the equation are compared to 3D finite element simulations which show agreement acceptable for most practical applications and over a wide range of physical dimensions and thermal conductivities. A norma-lized dimensional parameter is defined which is used to generate a curve fit equation of the spreading angle. A three step procedure is then presented which allows the calculation of the spreading angle and temperature rise in the thermal spreader. The result has application for initial calculations of temperature rise in microwave hybrid modules and electronic packages such as heat sinks for high power amplifiers. This is because it is common for these types of modules and packages to use a single layer heat spreader in copper-tungsten (CuW) or copper-molybde-num (CuMo) connected to a cold plate. An important benefit of this method is that it allows microwave hybrid designers and high power amplifier packaging engineers a method to quickly perform trade studies to determine the maximum mounting temperature for integrated circuits.

A Comparative Study of Williamson Hybrid Nanofluid Flow Consisting of Cu, GaN, and Al2O3 Nanoparticles in Ethylene Glycol over a Stretching Sheet with Suction/Injection and Heat Source/Sink

Several new techniques in the field of heat transfer in fluids have opened new avenues for studying the heat transfer effects in nanofluids and thermodynamic flow parameters, leading to novel applications. There have been studies on nanofluids, including metal, ceramic and magnetic nanoparticles mixed with base fluids such as Water, Kerosene, and Ethylene glycol. However, research on fluids employing semiconductor nanoparticles as supplements to base fluids to generate nanofluids and hybrid nanofluids is limited. For the investigation, Gallium nitrite, a binary semiconductor with excellent heat convection, is together with Cu metal nanoparticles and Al2O3 ceramic nanoparticles separately in the base fluid Ethylene glycol (EG) to form hybrid nanofluids. The effects of convective boundary conditions, thermal radiation, heat source/sink, suction/injection, and activation energy on three-dimensional Williamson MHD hybrid nanofluid flow of Cu + GaN + EG, Al2O3 + GaN + EG, and Cu + Al2O3 + EG are investigated on a stretched sheet with porosity. A similarity transformation is performed on the governing equations to transform them into dimensionless ordinary differential equations ODEs. Numerical analysis is carried out in MATLAB utilizing bvp5c and the shooting technique. The variations of velocity, temperature, and concentration profiles as a function of different physical effects are presented graphically with dimensionless parameters and explained the variations scientifically. As varied with different parameters, the values of the Skin-friction coefficient, Nusselt number, and Sherwood number are mentioned in the table.

基于混合正则化方法的结构载荷识别与响应重构

针对结构载荷识别与响应重构问题中存在的不适定性,提出一种最小平方残差(least square minimal residual,LSMR)算法与Tikhonov正则化方法相结合的混合正则化方法,实现利用结构有限测点的加速度响应识别载荷并重构未知的各类型响应。首先,基于时域状态空间模型构建结构的传递矩阵,并建立载荷识别与响应重构方程;其次,采用混合正则化方法改善载荷识别问题的不适定性,得到载荷的正则化解,并结合响应重构方程的传递矩阵对结构的位移、速度和加速度响应进行重构;最后,通过简支梁数值仿真和试验分析验证所提方法的可行性。结果表明,所提方法能改善重构方程的不适定性,从而对结构未知载荷和各类型响应进行有效重构。

SYNTHESIS AND CHARACTERIZATION OF STRUCTURALLY WELL-DEFINED POLYMER-INORGANIC HYBRID NANOPARTICLES VIA ATRP

Atom transfer radical polymerization (ATRP) using cuprous chloride/2,2'-bipyridine (bipy) was applied to graft polymerization of styrene on the surface of silica nanoparticles to synthesize polymer-inorganic hybrid nanoparticles, 2-(4Chloromethylphenyl) ethyltriethoxysilane (CTES) was immobilized on the surface of silica nanoparticles through condensation reaction of the silanol groups on silica with triethoxysilane group of CTES. Then ATRP of St was initiated by this surface-modified silica nanoparticles bearing benzyl chloride groups, and formed PSt graft chains on the surface of silica nanoparticles. The thickness of the graft chains increased with reaction time. End group analysis confirmed the occurrence of ATRP. Thermal analysis indicated that thermal stabilization of these resulting hybrid nanoparticles also increases with polymerization conversion. The results above show that this 'grafting from' reaction could be used for the preparation of polymer-inorganic hybrid nanoparticles with controlled structure of the polymer's end groups.

Multiple Energy Transfers in Rare Earth Complex-Doped SiO_2 Spheres

Silica spheres doped with Eu （TTFA）3 and/or Sm（TTFA）3 were synthesized by using the modified Stober method. The transmission electron microscope image reveals that the hybrid spheres have smooth surfaces and an average diameter of about 210 nm. Fluorescence spectrometer was used to analyze the fluorescence properties of hybrid spheres. The results show that multiple energy transfer processes are simultaneously achieved in the same samples co-doped with Eu （TTFA）3 and Sm（TTFA）3, namely between the ligand and Eu^3＋ ion, the ligand and Sm^3＋ ion, and Sm^3＋ ion and Eu^3＋ ion. Energy transfer of Sm^3＋→Eu^3＋ in the hybrid spheres leads to fluorescence enhancement of Eu^3＋ emission by approximately an order of magnitude. The lifetimes of the hybrid spheres were also measured.

高性能YVO_(4)基稀土杂化发光材料的构建及其能量传递机制

采用溶剂热和离子交换两步实验法,以YVO_(4)为无机基质,2-噻吩甲酰三氟丙酮(TTA)为有机配体,构建了具有核壳结构的YVO_(4)∶Eu^(3+)@YVO_(4)∶Eu^(3+)-TTA稀土杂化发光材料,研究了其高效的发光性能和内部的能量传递机制。结果表明,在621nm的监控波长下,YVO_(4)∶Eu^(3+)@YVO_(4)∶Eu^(3+)-TTA稀土杂化发光材料在280~420nm范围内有两个很强的吸收峰(即V-O峰和TTA特征吸收峰)。YVO_(4)基质通过交换作用能量传递,而TTA有机配体通过分子内能量传递,可将吸收的紫外光能量有效地传递给Eu^(3+),从而实现了Eu^(3+)更高效的可见光(红光)发射。

不同分数导数下Maxwell杂化纳米流体流动和传热变化的灵敏度分析

研究多孔介质中垂直拉伸板引起的分数阶Maxwell杂化纳米流体流动与传热现象,并考虑二阶滑移边界条件.利用分数阶剪应力和分数阶Fourier定律构建边界层控制方程.然后采用有限差分结合L1算法进行数值求解,并详细讨论分数导数参数增大时,各物理参数对该流体流动与传热影响的灵敏度变化.结果表明,Darcy数和滑移参数对平均表面摩擦系数的影响,以及滑移参数对平均Nusselt数的影响,对速度分数导数比对温度分数导数更敏感.Darcy数对平均Nusselt数的影响只对温度分数导数敏感,与速度分数导数几乎无关.此外,一阶滑移参数比二阶滑移参数对流动和传热的影响更大.

复合纳米流体强化换热研究进展

随着科学技术的进步,电子器件、太阳能和机械加工等系统均趋向于高功率和微型化发展.然而,这些系统内部产生的热量也随之增加,导致系统过热甚至烧毁,因此,亟需发展高效热管理系统,以及时带走系统热量.近年来,多种新型热管理技术被广泛研究和应用,其中,复合纳米流体强化换热技术因具有效果显著、成本低廉和无额外能耗等优势而备受关注,成为研究和应用的热点之一.本文对复合纳米流体强化换热技术的研究进展进行全面综述.首先总结了近年来复合纳米流体制备的研究现状,然后分析了复合纳米流体的一般性能、传热性能及相关影响因素,着重讨论了复合纳米流体强化换热机制.此外,还介绍了复合纳米流体在微电子、太阳能装置及散热器等领域的应用.最后,讨论了复合纳米流体强化换热技术目前面临的挑战,并提出了未来的发展方向.

基于深度学习的产品风格精细识别

为有效提取具有差异性的产品风格特征,提出一种基于复合学习通路的细粒度风格识别卷积神经网络(FSR-CNN)。一是注意力学习通路,以残差结构为基础,采用串并结合的方式将坐标注意力、卷积块注意力和多头注意力嵌入其中,提出轻量化的混合注意力残差网络(HA-ResNet),用于抽取“专用特征”。二是迁移学习通路,应用微调预先训练的GoogLeNet以扩充HA-ResNet模型容量,实现多感受野“通用特征”抽取。最后对二者输出的特征进行融合,并使用MLP分类器识别产品风格类型。在自行车头盔数据集上进行实验,并与其他经典深度卷积神经网络模型进行比较,实验结果表明FSR-CNN模型表现出较高的准确率和良好的稳健性,为产品风格精细检索与知识重用提供了一种新的模型算法架构。

基于蓝光HLCT材料pCzAnN作敏化主体的单发光层白光有机发光二极管

有机发光二极管(Organic light-emitting diodes,OLEDs)作为照明和显示领域极其具有竞争力的技术,近年来备受关注。实现超简单、高效率、低滚降的白光OLEDs,对有机发光层材料的选择至关重要。杂化局部和电荷转移(Hybridized local and charge transfer,HLCT)材料的“热激子”通道可以将高能三线态激子窜跃至单线态,实现理论上100%的激子利用率,快速的反向系间窜跃可有效抑制三线态激子猝灭,从而降低器件效率滚降。基于此,本文首先通过电荷平衡策略优化器件结构,制备了基于HLCT材料pCzAnN的高效蓝光OLED。在此基础上,以pCzAnN作为传统荧光材料的敏化主体,通过不完全能量传递策略,实现了双色及三色白光OLEDs制备。制备的白光OLEDs最高显色指数达到90,最大外量子效率达到8.76%,且展现出较低效率滚降及良好的光谱稳定性。本研究对开发简单、高效率、低滚降白光OLEDs具有指导意义。