60 GHz Radio over Fiber Technology for Wireless Access by employing Narrow-Angle PSK Modulation

This paper investigates two key techniques used in 60 GHz Radio over Fiber (RoF) technology for wireless access, namely, the generation of 60 GHz signals and the distribution of 60 GHz local oscillator (LO). In the proposed model, a 60 GHz PSK signal is generated by a heterodyne of two subcarriers with narrow-angle PSK (NA-PSK) modulation, whose phase shift is equal to one half that of a normal PSK signal. Then we use a 60 GHz mixer to frequency mix two PSK signals in two different bands, 60 GHz and baseband. By doing this, the modulation information can be fully eliminated, resulting in a 60 GHz LO. In the wireless terminal, coherent demodulation is realized by a self-mixing of the transmitted 60 GHz PSK signal and LO. Thus no millimeter-wave (mm-wave) band oscillator is needed in the wireless terminal.     

直线加速器同轴负载材料FeSiAl的电磁参数测试及仿真

 为获得直线加速器同轴负载材料FeSiAl的介电常数和磁导率,基于同轴传输反射法,利用矢量网络分析仪,对同轴负载磁性吸波材料FeSiAl的电磁参数进行了测试研究,同时利用电磁场分析软件Microwave Studio进行了测试仿真。研究表明,测量中加工样品与其夹具之间的装配间隙对电磁参数的测试值存在较大影响,进而制作了不同配比的FeSiAl微粉和固体石蜡混合样品,获得混合样品的稳定测试值。对求取电磁参数等效公式的适用性研究表明,Bruggeman,Looyenga,QCACP公式适用于描述该FeSiAl微粉的电磁特性,最后给出了FeSiAl材料的电磁参数。     

Sparsely sampled high-resolution 4-D experiments for efficient backbone resonance assignment of disordered proteins

Intrinsically disordered proteins (IDPs) play important roles in many critical cellular processes. Due to their limited chemical shift dispersion, IDPs often require four pairs of resonance connectivities (H(α), C(α), C(β) and CO) for establishing sequential backbone assignment. Because most conventional 4-D triple-resonance experiments share an overlapping C(α) evolution period, combining existing 4-D experiments does not offer an optimal solution for non-redundant collection of a complete set of backbone resonances. Using alternative chemical shift evolution schemes, we propose a new pair of 4-D triple-resonance experiments--HA(CA)CO(CA)NH/HA(CA)CONH--that complement the 4-D HNCACB/HN(CO)CACB experiments to provide complete backbone resonance information. Collection of high-resolution 4-D spectra with sparse sampling and FFT-CLEAN processing enables efficient acquisition and assignment of complete backbone resonances of IDPs. Importantly, because the CLEAN procedure iteratively identifies resonance signals and removes their associating aliasing artifacts, it greatly reduces the dependence of the reconstruction quality on sampling schemes and produces high-quality spectra even with less-than-optimal sampling schemes.     

A new kind of nonlinear fractional-order chaotic phenomenon in coupled systems： coexistence of anti-phase and complete synchronization

In this paper, we have found a kind of interesting nonlinear phenomenon hybrid synchronization in linearly coupled fractional-order chaotic systems. This new synchronization mechanism, i.e., part of state variables are anti- phase synchronized and part completely synchronized, can be achieved using a single linear controller with only one drive variable. Based on the stability theory of the fractional-order system, we investigated the possible existence of this new synchronization mechanism. Moreover, a helpful theorem, serving as a determinant for the gain of the controller, is also presented. Solutions of coupled systems are obtained numerically by an improved Adams Bashforth-Moulton algorithm. To support our theoretical analysis, simulation results are given.     

Measurements on diproton emission from the break-up channels of ~(23)Al and ~(22)Mg

Two-proton relative momentum distributions from the break-up channels 23Al→p+p+21Na and 22Mg→p+p+20Ne at an energy of 60-70 A MeV have been measured together with two-proton opening angles at the projectile fragment separator beamline (RIPS) in the RIKEN Ring Cyclotron Facility. The results demonstrate the existence of diproton emission component from single-step 2He for highly excited 23Al and 22Mg.     

铕与4-(4-吡啶甲酰基)苯甲酸配合物的合成与荧光性能研究

以Eu3+为中心离子,4-(4-吡啶甲酰基)苯甲酸(HPFBA)、1,10-菲罗啉(Phen)和三苯基氧膦(TPPO)为配体,合成了新型配合物Eu(PFBA)3(H2O)4,Eu(PFBA)3Phen(H2O)3和Eu(PFBA)3TPPO(H2O)3(PFBA=4-(4-吡啶甲酰基)苯甲酸根).红外光谱表明,形成配合...     

三角形谱啁啾光纤光栅的制备及其在光纤无线单边带调制系统中的应用

本文涉及一种三角形谱啁啾光纤光栅的制备以及其在光纤无线(radio over fiber,RoF)单边带调制系统中的应用.基于相位掩模法和变速度折射率调制,实验制备了底部变化范围1.9 nm、透射深度0—15 dB的三角形谱啁啾光纤Bragg光栅,利用其透射谱具有较大负向斜边,研究了其在RoF系统中的应用.方案仅使用一个三角形谱光纤光栅,实现了以下两种功能: 1)双边带调制信号到单边带调制信号转换; 2)降低信号的载波边带比(carrier-to-sideband ratio,CSR),提高接收灵敏度.并 关键词： 光纤通信 微波光子 光纤布拉格光栅 单边带调制     

Large-scale synthesis and the roles of growth conditions on the formation of Zn2GeO4 nanorods

Large-scale Zn₂GeO₄ nanorods with a length of about 10 μm have been synthesized via a facile hydrothermal process in the absence of any surfactant. The synthesized nanorods are single crystals with a rhombohedral phase. The dependence on the growth conditions, such as reaction temperature, reaction time, compactness and GeO₂ concentration, of the formation, morphologies and sizes of the Zn₂GeO₄ nanostructures has been investigated. Proper selection and combination of the growth conditions are the key aspects to control the formation, morphologies and sizes of the Zn₂GeO₄ nanostructures. The nucleation and crystalline growth mechanism are proposed to explain the formation and growth of Zn₂GeO₄ nanorods. The photoluminescence spectrum of the Zn₂GeO₄ nanorods exhibits three fluorescence emission peaks centered at 421, 488 and 529 nm when the excitation wavelength is 235 nm.     

A new probe of neutron skin thickness

The correlation between neutron-to-proton yield ratio (R_np) and neutron skin thickness (δ_np) in neutron-rich projectile induced reactions is investigated within the framework of the Isospin-Dependent Quantum Molecular Dynamics (IQMD) model. The density distribution of the Droplet model is embedded in the initialization of the neutron and proton densities in the present IQMD model. By adjusting the diffuseness parameter of neutron density in the Droplet model for the projectile, the relationship between the neutron skin thickness and the corresponding R_np is obtained. The results show strong linear correlation between R_np and δ_np for neutron-rich Ca and Ni isotopes. It is suggested that R_np may be used as an experimental observable to extract δ_np for neutron-rich nuclei, which is very interesting in the study of the nuclear structure of exotic nuclei, the equation of state (EOS) of asymmetric nuclear matter and neutron-rich matter in astrophysics, etc.     

Effective mechanism for social recommendation of news

Recommender systems represent an important tool for news distribution on the Internet. In this work we modify a recently proposed social recommendation model in order to deal with no explicit ratings of users on news. The model consists of a network of users which continually adapts in order to achieve an efficient news traffic. To optimize the network’s topology we propose different stochastic algorithms that are scalable with respect to the network’s size. Agent-based simulations reveal the features and the performance of these algorithms. To overcome the resultant drawbacks of each method we introduce two improved algorithms and show that they can optimize the network’s topology almost as fast and effectively as other not-scalable methods that make use of much more information.