Multi-band spectrum auction framework based on location information in cognitive radio networks

Cognitive radio（CR） technology is considered to be an effective solution to allocate spectrum resources,whereas the primary users of a network do not fully utilize available frequency bands.Spectrum auction framework has been recognized as an effective way to achieve dynamic spectrum access.From the perspective of spectrum auction,multi-band multi-user auction provides a new challenge for spectrum management.This paper proposes an auction framework based on location information for multi-band multi-user spectrum allocation.The performance of the proposed framework is compared with that of traditional auction framework based on a binary interference model as a benchmark.Simulation results show that primary users will obtain more total system revenue by selling their idle frequency bands to secondary users and the spectrum utilization of the proposed framework is more effective and fairer.

NOLM-based Mode-locked Yb-doped Fiber Laser with Wide-spectrum

In this paper,a mode-locked Ytterbiumdoped fiber laser based on nonlinear optical loop mirror(NOLM)is proposed.The laser generates a wide-spectrum dissipative soliton resonance modelocked pulse with strong stimulated Raman scattering.The fiber laser is pumped forward,and the fiber ring cavity contains double-cladding Yb-doped fiber,output coupler,polarization controller,polarization independent isolator and other elements.NOLM is connected with the ring cavity by through a 3dB beam splitter and 25m single-mode fiber.The total length of the eight-shape cavity laser is about 60meters.By adjusting the intra-cavity polarization controller,a stable dissipative soliton resonance mode-locked spike pulse can be achieved.The repetition frequency of the pulse train is 3.44MHz,which is consistent with the cavity length.The 3dB bandwidth of the spectrum reaches 70.6nm,and the 10dB bandwidth is close to 147.11nm.In this experiment,dissipative soliton resonance mode-locked pulses with wide spectrum and high pulse energy are realized by a traditional modelocking method,which has wide application in many fields such as laser spectral detection and terahertz wave generation.

2-D SPATIAL-SPECTRUM ESTIMATION FORWIDE-BAND SOURCES BASED ON INTERPOLATED CIRCULAR ARRAYS

In array signal processing, 2-D spatial-spectrum estimation is required to determine DOA of multiple signals. The circular array of sensors is found to possess several nice properties for DOA estimation of wide-band sources. C. U. Padmini, et al.(1994) had suggested that the frequency-direction ambiguity in azimuth estimation of wide-baud signals received by a uniform linear array (ULA) can be avoided by using a circular array, even without the use of any delay elements. In 2-D spatial-spectrum estimation for wide-band signals, the authors find that it is impossible to avoid the ambiguity in source frequency-elevation angle pairs using a circular array. In this paper, interpolated circular arrays are used to perform 2-D spatial-spectrum estimation for wide-band sources. In the estimation, a large aperture circular array (Υ】λmin/2) is found to possess superior resolution capability and robustness.

Hot‐electron‐assisted S‐scheme heterojunction of tungsten oxide/graphitic carbon nitride for broad‐spectrum photocatalytic H_(2)generation

Extended light absorption and dynamic charge separation are vital factors that determine the effectivenessof photocatalysts.In this study,a nonmetallic plasmonic S‐scheme photocatalyst was fabricatedby loading 1D plasmonic W_(18)O_(49)nanowires onto 2D g‐C_(3)N_(4)nanosheets.W_(18)O_(49)nanowiresplay the dual role of a light absorption antenna—that extends light adsorption—and a hot electrondonor—that assists the water reduction reaction in a wider light spectrum range.Moreover,S‐scheme charge transfer resulting from the matching bandgaps of W_(18)O_(49)and g‐C_(3)N_(4)can lead tostrong redox capability and high migration speed of the photoinduced charges.Consequently,in thisstudy,W_(18)O_(49)/g‐C_(3)N_(4)hybrids exhibited higher photocatalytic H2 generation than that of pristineg‐C_(3)N_(4)under light irradiation of 420–550 nm.Furthermore,the H2 production rate of thebest‐performing W_(18)O_(49)/g‐C_(3)N_(4)hybrid was 41.5μmol·g^(−1)·h^(−1)upon exposure to monochromaticlight at 550 nm,whereas pure g‐C_(3)N_(4)showed negligible activity.This study promotes novel andenvironmentally friendly hot‐electron‐assisted S‐scheme photocatalysts for the broad‐spectrumutilization of solar light.

FAST ALGORITHM FOR NON-UNIFORMLY SAMPLED SIGNAL SPECTRUM RECONSTRUCTION

In this paper, a fast algorithm to reconstruct the spectrum of non-uniformly sampled signals is proposed. Compared with the original algorithm, the fast algorithm has a higher computational efficiency, especially when sampling sequence is long. Particularly, a transformation matrix is built, and the reconstructed spectrum is perfectly synthesized from the spectrum of every sampling channel. The fast algorithm has solved efficiency issues of spectrum reconstruction algorithm, and making it possible for the actual application of spectrum reconstruction algorithm in multi-channel Synthetic Aperture Radar (SAR).

红外超宽带分光镜研究

超宽带分光镜是光谱分析系统中不可缺少的光学元件,其性能直接影响傅里叶红外光谱仪的测试精度。依据光学薄膜理论,选用Ge、ZnSe和YbF_(3)作为镀膜材料,结合基板实际光谱曲线,通过光谱补偿设计方法,结合TFC软件完成膜系设计。采用电子束蒸发离子束辅助沉积技术进行薄膜制备,通过优化沉积工艺,解决了分光镜制备过程中膜厚控制误差大导致光谱差的问题。使用Spectrum Two傅里叶红外光谱仪进行检测,在45°入射时,2.5μm~20μm波段的平均分光比为52:45.5,且环境测试结果显示,分光镜具有良好的稳定性。

An Advanced Multi-Band Acousto-Optical Radio-Wave Spectrometer with Multi-Channel Frequency Processing for Astrophysical Studies

We present an advanced schematic arrangement of the radio-wave spectrometer with a few parallel optical arms for processing the data flow. This arrangement includes two principal novelties. First of them consists in the proposed design, where each individual optical arm exhibits its original performances providing parallel multi-band observations within a few different scales simultaneously. These optical arms have the beam shapers providing both the needed incident light polarization and apodization to increase the dynamic range. After parallel acousto-optical processing, data flows of all the optical arms are united by the joint CCD matrix on the stage of the combined electronic data processing. The second novelty is in usage of unique wide-aperture bastron-based acousto-optical cell providing one of the best performances at the middle-frequencies (about 500 MHz) in comparison with the other available crystalline materials in this range. Such multi-band capabilities have a number of applications in astrophysical scenarios at different scales: from objects in the distant universe to planetary atmospheres in the Solar system. Thus one yields the united versatile instrument, which provides comprehensive studies of astrophysical objects simultaneously with precise synchronization in various frequency ranges.

Flexible regulation engineering of titanium nitride nanofibrous membranes for efficient electromagnetic microwave absorption in wide temperature spectrum

Simultaneous development of well impedance matching and strong loss capability has become a mainstream method for achieving outstanding electromagnetic microwave absorption(EMWA)performances over wide temperature range.However,it is difficult to pursue both due to the mutual restraint of relationship between impedance matching and loss capability about temperature.Here,we propose a flexible regulation engineering of titanium nitride(TiN)nanofibrous membranes(NMs,TNMs),which could be distributed uniformly in the polydimethylsiloxane(PDMS)matrix and contributed to the formation of abundant local conductive networks,generating the local conductive loss and enhancing the loss ability of EMWs.Moreover,when the TNMs are used as functional units and dispersed in the matrix,the corresponding composites exhibit an outstanding anti-reflection effect on microwaves.As hoped,under the precondition of good impedance matching,local conductive loss and polarization loss together improve the loss capacity at room temperature,and polarization loss can compensate the local conductive loss to acquire effective dielectric response at elevated temperature.Benefiting from the reasonably synergistic loss ability caused by flexible regulation engineering,the corresponding composites exhibit the perfect EMWA performances in a wide temperature range from 298 to 573 K.This work not only elaborates the ponderable insights of independent membrane in the composition-structure-function connection,but also provides a feasible tactic for resolving coexistence of well impedance matching and strong loss capability issues in wide temperature spectrum.

1μm/1.5μm基于非互易性相移器的高重频飞秒光纤激光器

高重频的飞秒脉冲激光器在工业加工、医疗、精密测量等各个领域都有着重要应用。为了分析“9”字腔锁模激光器的自启动性能,利用琼斯矩阵建立了非线性放大环形镜的传输函数,分析了环形镜中不同波片角度对腔内往返传输函数的影响。搭建了基于非线性放大环形镜的光纤激光器,分别使用了掺镱光纤、掺铒光纤作为增益介质,在1μm和1.5μm波段分别实现了重复频率为600 MHz和280 MHz的基频锁模。所设计的激光器具有脉宽窄、光谱宽、稳定性好、自启动成功率高的特点,激光器完成了集成化封装,能够满足微纳加工、激光医疗、光频率梳等领域对飞秒激光的应用需求。

宽光谱多传感器轴一致性检测系统设计

光轴一致性是衡量多传感器光电系统工作性能的重要指标,为了解决多传感器轴一致性检测系统工作波段范围较窄、系统灵活性较低的问题,本文结合光路切换和光热转换的思想,设计了一套宽光谱多传感器轴一致性检测系统。该系统采用卡塞格林反射式光学系统作为从可见光到长波红外范围内的接收和发射系统;通过步进电机的驱动,带动导轨上方反光镜位置移动,实现系统光路的切换;采用镀有硫化铜的锗玻璃,作为光热转换靶材,将短波长的光斑转换为热斑,采用长波红外探测器实现对各波段激光光斑图像采集。系统能够实现0.4~14μm波段光谱范围的检测;对光学系统进行像质评价分析,可以得到系统在不同波段下由像差引起的弥散斑(Root mean square,RMS)直径均在9μm以下,能量集中度较好;对系统检测精度进行分析,最大测量误差为0.1 mrad;通过导轨往返运动重复精度实验和系统测量准确度实验,对系统可靠性进行验证,结果表明检测系统满足仪表准确度1.5级的要求。该检测系统结构紧凑,适用波谱范围广,能够实现对多传感器光电设备的轴一致性检测。

光-电协同调控的高反射率全彩色液晶器件

本文利用光-电协同调控的方法获得了具有高反射率、全彩色显示的倾斜螺旋胆甾相(ChOH)器件。在液晶体系中引入一种具有左旋旋向的手性光开关switch 1,并基于相反旋向手性添加剂的手性抵消原则,使用R811来平衡switch 1发生光致Z/E异构化前后螺旋扭曲力上的差异,使体系在光照前后对其施加相同的电场强度可以反射具有相反旋向且相同波段的红-绿-蓝三色光。在此基础上,构筑了双层结构的液晶器件,对材料进行分层光-电刺激,诱导上层螺旋结构翻转,可在双层结构中分别形成左右旋结构,从而具有全反射效应,在双层ChOH液晶器件中反射率提升约60%。本研究为制备具有高反射率的全彩色电子纸器件提供了新思路,同时也为光开关材料在液晶器件中的应用提供了有益的探索。

0.2 μm~20 μm超宽光谱超材料吸波结构设计与仿真

为了实现对从紫外到红外超宽光学谱段辐射的高效吸收,设计了0.2 μm~20 μm波长范围内高吸收效率的超材料吸波结构。采用超宽带分区设置、5分离层结构优化设计、非均匀采样等方法获得了3尺度5分离层超材料吸波结构的等效谐振电路参数,确定了各分离层结构参数,分析讨论了吸波性能。仿真实验结果表明:超材料吸波结构总厚度约3.14 μm,在0.2 μm~20 μm波长范围内吸收效率优于89%,有效吸波带宽比接近100%,满足超宽光谱超材料吸波结构波长范围和吸收效率约束。设计方法在超宽带频率范围内可实现一致性连续吸波结构设计,各分区吸波带宽比预期带宽拓展约45.26%,整体吸收带宽比预期带宽拓展约81.57%,吸收效率优于80%的有效吸收带宽比约85.11%,适用于超宽光谱探测与对抗隐身。

用于宽谱光学耦合的CdTe纳米线与硅波导复合耦合结构设计

设计了一种基于CdTe纳米线与硅波导的复合光学耦合结构,利用光学绝热耦合实现了CdTe纳米线与片上硅波导的高效率、宽光谱耦合。采用时域有限差分法,研究了CdTe纳米线与硅波导的模式匹配情况,并建立了CdTe纳米线与硅波导复合结构的耦合理论模型。在实验中,将通过气相沉积法制备得到的CdTe纳米线与通过光刻工艺制备得到的硅波导组成复合耦合结构,并利用光谱仪测量耦合特性。实验结果表明,当CdTe纳米线与硅波导的耦合长度~10μm时,在波长1150~1650 nm范围内的耦合效率>90%,耦合带宽达到了500 nm。所提出的耦合结构具有耦合长度短、耦合带宽大、纳米线材料可选择性高、耦合结构可重复构建等特点,可用于片上波分复用器、集成光学传感器等光通信或光传感器件与系统的研制。

基于色散补偿的宽光谱“9”字腔掺镱光纤激光器

超快激光器凭借其脉宽窄、光谱宽、峰值功率高等特点,在工业、医疗、科研等许多领域有着重要应用。通过在“9”字腔内进行色散补偿,激光器可以同时实现宽光谱输出与自启动锁模,当泵浦功率为160 mW时,光谱中连续光成分消失,两输出口的光谱半高全宽为22.6 nm和26.2 nm,压缩后脉冲宽度达到143 fs和128 fs。在自由运转情况下,1 h内输出激光的平均功率均方根值(root mean square,RMS)为0.1%。所设计的激光器具有光谱宽、集成度高、稳定性强的优点,能够满足微纳加工、生物光学、光谱探测等领域对超快激光的应用需求。

宽波段折反射式航空相机设计

为了在15000m平流层实现对地全天候观测,满足工作波段470~1500nm对地分辨率达到0.1m的要求,设计了一种长焦距折反式高分辨率CCD航空相机。通过使用H-ZK7与ZF6搭配,对长焦距和大孔径产生的二次光谱进行校正,倍率色差控满足设计要求。通过对光学系统热分析,分析出系统在不同高度下温度变化对成像质量的变化曲线。探测器采用徕卡公司M9全画幅CCD探测器,其单像元为8μm,靶面尺寸为48 mm×36 mm;系统在100 lp/mm时达到衍射极限,满足系统成像要求。

宽谱域光电探测器阵列信号实时处理算法优化研究

宽谱域光电探测器阵列是一种先进的光电设备,能够在广泛的光谱范围内检测光信号,光谱范围覆盖从红外到紫外的大部分光谱。然而,宽谱域探测器产生的数据量巨大,对实时处理算法提出了极高的要求。本文介绍了宽谱域光电探测器阵列的基本原理,探讨了新型算法的设计与优化方法。实践证明,该优化方法能够显著提高宽谱域光电探测器阵列信号的实时处理效率。

基于波动方程反射波反演的速度模型宽谱重构方法及其海上拖缆数据应用

常规地震勘探中,地震数据大都缺少大炮检距信号和有效的低频成分,使得传统的全波形反演(FWI)方法很难恢复中、深层参数模型的低波数分量。依据多尺度反演思想,采用基于模型分解的波动方程反射波反演方法重构宽谱速度模型,同时提出自适应构造约束的模型正则化方法优化反演结果,提高反演稳定性。以Sigsbee模型数据为例展示了该方法是如何有效地同时重构宏观速度模型(长波长)和速度扰动(短波长)或反射率结构的。将所提方法用于东海拖缆采集数据,利用走时到波形信息匹配的波动方程反射波反演策略,构建了与地层更加吻合的宏观背景模型,获得了高分辨的地层成像剖面,成像道集平整度与成像剖面的连续性有明显提高,深部基底的成像更加清晰。

一种用于监控侦察的大视场宽光谱光学系统设计

为了满足监控侦察对光学系统日夜两用及监控范围广的需求,运用像差分析方法和光学设计软件设计了一种大视场宽光谱光学系统。设计的光学系统由7片透镜组成,所有透镜的光学面均采用球面设计,工作波段为400~1100 nm,最大全视场角达到140°,焦距为2.33 mm,f数为5,后工作距离为7.42 mm;在奈奎斯特频率42 lp/mm处,视场角范围的调制传递函数值均大于0.28,相对照度均大于96%,最大视场角的F-theta畸变值为27.85%;最后,对设计的光学系统中各类型公差进行了分析。结果表明,设计的光学系统像差校正较好,具有较好的成像质量且易于加工。

广谱抗生素应用对小婴儿肠道微生态的影响

目的 :探讨抗生素对小婴儿肠道微生态的影响 ,评价便涂片法监测小婴儿肠道菌群变化的可行性。方法 :对 3 0例应用广谱抗生素治疗的 3个月以下小婴儿 (试验组 )及 3 2例同年龄正常儿 (对照组 ) ,用便涂片直接镜检法进行肠道菌群的初步分析和监测。结果 :应用抗生素 3～ 15d,试验组革兰阴性杆菌比例明显下降 ,革兰阴性杆菌生长受抑制 ,革兰阳性球菌渐表现出优势生长。因此 ,对应用抗生素的患儿应尽早应用微生态制剂调整肠道菌群。结论 :应用便涂片直接检菌法可帮助临床医生初步判定小婴儿肠道菌群的变化情况 ,简便、经济。

宽谱段折射式长焦光学镜头

介绍了宽谱段、折射式长焦镜头的光学设计 重点讨论了宽谱段 (4 2 0～ 90 0nm)二级光谱的校正问题 ,修正了部分色散 (P)和阿贝数 (V)的计算公式 ,使之适合于宽谱段光学系统的设计 ,并给出了设计实例及设计结果 本系统理论上的二级光谱约为 1.2mm ,而设计结果使三条谱线 (4 2 0nm、6 0 0nm、90 0nm)基本交于一点 ,实际二级光谱约 0 .2