植物超弱发光的探测

采用超弱发光图像探测系统对蟛蜞菊、千日红花蕾、翠菊等植物样品进行了自发和光诱导的超弱发光图像探测,对大花紫薇叶片的延迟发光进行了初步的光谱探测。结果表明：植物自发发光与延迟发光的强度及其分布是有区别的,自发光光强度远小于延迟发光强度;与有丝分裂和生长代谢有关的植物超弱发光有光诱导下得以加强;千日红花蕾的延迟发光遵循双曲线衰减规律,说明生物光子具有一定的相干性;叶片的延迟发光光谱比离体叶绿素荧光光谱     

近红外有机小分子电致发光材料研究进展

近红外有机发光材料与器件在信息安全、光纤通信、生物成像、医学诊断等重要领域具有广阔的应用前景。近几年,基于热激发延迟荧光、局域电荷转移杂化态、发光自由基的双重态激子发光等机理,电致发光过程中激子的利用率已达到100%,大幅提高了近红外有机电致发光器件的性能。本文综述了近红外有机小分子电致发光材料的研究进展。根据不同的发光机理对材料进行了分类,对各类发光机理及材料与器件的性能进行了总结,并对未来的发展前景进行了展望。     

生物超弱发光采集系统及控制电路设计

生物超弱发光是生物系统在生命活动中的微弱发光现象。为了准确测量生物超弱发光,设计了一种用于生物超微弱发光的专用采集系统。系统的激发光源由单只大功率LED及光学系统构成,用压控恒流源调整LED光照强度,通过电子快门精确控制光探测器的采集时间。测量金心吊兰叶片的延迟发光结果表明,该系统测量精度高、重复性好。     

一种新型自聚集诱导发光材料的研究

为了研究一种新型的聚集诱导发光材料(1-绕丹宁-芘),采用荧光光谱测量法和ORIGIN软件对样品进行了实验验证和理论分析,发现其具有一些新颖的光学性质。结果表明,在稀释溶液浓度时,样品的发射峰出现大幅蓝移;在升高温度时,样品出现了荧光增强现象。这些性质不同于常见的聚集诱导发光材料,与1-绕丹宁-芘在溶液中聚集时生成超分子结构有关。该研究在生物成像、医学领域、传感器、探测器及有机显示方面有一定的应用前景,对有机发光材料的研究有重要的意义。     

基于光诱导延迟发光的微量毒品检测研究

基于单光子计数测量原理,设计并构建了基于光 诱导延迟发光的微量毒品检测系统。对检测系统的性 能进行了评测,结果显示,光电倍增管(PMT)的固有暗计数为11.5±0.7 photon/s,系统 暗计数为11.7±0.7 photon/s,对外界杂散光的屏蔽性能优异。利用本系统检测得到了健 康人和涉嫌吸食冰毒人员的血 清样本的延迟发光衰减曲线和参数值,结果表明,两种样本的各个参数值差异非常明显 。本检测系统灵敏 度高,所需样品量少,检测过程不与样品直接接触,为生物样本中微量毒品的检测提供了强 有力的工具。     

基于激发光可调的超微弱发光探测系统

鉴于目前超微弱发光探测仪器的功能单一,设计了一种把激励光源与探测合为一体的,用于探测生物超微弱发光探测系统.激励光源由高亮度的LED阵列、光学系统构成,用可调恒流源调节LED发光强度.采用多重密封方法来降低系统噪声,将噪声控制在50cps之下.并对兰花叶片进行了生物超微弱延迟发光探测,取得了比较好的探测效果.     

血清微弱发光的实验研究与应用

采用微弱发光检测系统,研究了血清的微弱发光。测试了健康人、高血糖和高血脂病人血清样品的微弱发光,探讨了血清的发光强度随血清中血糖和三酰甘油浓度变化的规律,并用编制的软件,实现了血清微弱发光图像的定量分析。实验结果表明,血糖浓度增加会导致血清的发光强度单调递增,微弱发光图像的灰度值增加;三酰甘油血清发光图像的灰度值也随着血脂浓度的增加而变大。与血糖相比,血清发光强度随三酰甘油浓度变化的效果不是十分明显。因此,可以采用血清的发光强弱来判断血清中血糖含量是否超标,此方法可有效地分析血清中血糖是否异常。     

基于STM32微控制器的生物延迟发光光谱探测系统

以STM32F103VET6微控制器作为系统控制核心,在对光照时间、延迟时间、脉冲采集时间精确控制的基础上,选取止度较深、波长控制精确的滤光片,配合单光子计数器,设计一套基于微控制器的生物延迟发光光谱探测系统。对小麦延迟发光光谱进行探测,测试结果表明:小麦延迟发光强STM32要集中在波长525 nm以上,且在640 nm附近存在明显峰值。     

稀土上转换发光微纳材料的光物理研究

稀土类发光材料由于其丰富的光学特性而具有重要的研究与应用价值。其中,稀土上转换发光材料在近年来尤为受人瞩目,与之相关的研究成果遍布物理、化学、生物、材料和多个交叉领域。有别于大多数发光材料的共性,上转换材料的激发-发射谱峰波长呈现为反斯托克斯位移,因此能够在短波长谱带范围绕过背景噪声且传输发光信息。作为对这一光物理机制的理解运用,人们通过化学方法合成了纳米尺度的稀土上转换发光材料,并且在生物样品荧光显微成像中成功证实了上转换发光标记物的高信噪比检测。以上转换发光微纳材料的光物理性质研究为主题,介绍和梳理了稀土上转换纳米材料在偏振光谱解析、单纳米颗粒超分辨发光成像、微型激光器构筑方面的研究进展。     

激光脉冲诱发的生物发光

研究者们已经在实验室里探测到生存在海底的微小单细胞植物的生物发光，这种发光是用激光诱发的。他们希望能用这种效应来探测诸如潜艇和商业上重要的鱼类等目标。但是，必须首先证实探测天然海洋环境中微生物的可能性，然后弄清楚这些微生物和鱼类及潜艇的关系。     

SDMA系统DL方案阻塞率的仿真

多址接入技术是无线通信系统设计的一个重要因素,未来无线通信系统将广泛采用空分多址（SDMA）接入技术来提高系统容量。比如在频分复用（FDMA）,时分复用（TDMA）,码分复用（CDMA）。介绍了Erlang-B分布这一典型的业务分配模型,并考虑了SDMA系统中DL信道分配机制,给出了理论推导,并采用一般的排队论模型对数字蜂窝移动通信系统中SDMA技术进行仿真。仿真结果表明：采用DL信道分配机制以后,用户可以在同一时间共享同一信道。     

A Novel Reverse-Microscope Antenna for Millimeter-wave Applications

In this paper, a Novel Reverse-Microscope Antenna (NRMA) that consists of a diffractive lens (DL) and an extended hemispherical lens (EHL), is proposed and analyzed by a two-dimension finite-difference time-domain (2-D FDTD) method. Based on the proposed structure, two NRMAs which use two-phase-level and four-phase-level DLs, are investigated and then compared with their conventional counterpart. The numerical results show that the diffraction efficiency of a NRMA with a four-phase-level DL is very close to that of a Conventional Reverse-Microscope Antenna (CRMA). Furthermore, the adopted DL is not only relatively flat and easy to fabricate compared with the conventional structure, but also portions from reduced thickness, light weight, low absorption loss, and other parameters. Therefore, the proposed NRMA with a four-phase-level DL is a valid substitute for the CRMA. The numerical methods have also been verified by the relative experimental results.     

波片相位延迟的精确测量及影响因素分析

提出一种精确测量波片相位延迟的方法。将待测波片置于起偏器和检偏器之间,转动待测波片和检偏器至不同的位置并探测输出的光强,得到波片的相位延迟。采用光源调制技术和解调技术,抑制了连续光所无法克服的背景光干扰和电子噪声的干扰;将光路分为测量光路和参考光路,采用软件除法技术,消除了光源波动的影响,从而实现波片相位延迟的精确测量。详细分析了影响测量精度的误差因素,主要有光源波长变化、温度变化、入射角倾斜、转台转角误差和光源波动,计算了1064 nm波长时厚度为0.52 mm的λ/4多级结晶石英波片产生的相位延迟误差,其中光源波动的影响在作除法后有显著的改善,各误差因素的总测量误差为±1.58°。实际测量了该λ/4结晶石英波片的相位延迟为91.06°±1.78°,与理论分析相符。该测量和误差分析方法同样适合其他的波片。     

基于中值的JS散度可变剪接差异分析研究

可变剪接是一种广泛存在于生物体中造成蛋白质多样性的重要机制，它对细胞的增殖、分化、发育、凋亡等一系列重要的生物过程具有重要精细调控的作用。近年来，人们发现多种复杂疾病的产生往往伴随着剪接异构体的紊乱表达。为了研究剪接异构体在整体分布上的差异，该文提出一种基于中值的JS散度可变剪接(AS)差异分析方法。结果表明，该文的方法能够发现大量在剪接异构体整体分布上具有显著差异的基因。这些基因不仅富集在一些癌症密切相关的通路，而且也富集在一些基于可变剪接调控的信号通路、细胞分裂过程和蛋白质功能等通路。此外，与基因层次的差异分析相比，可变剪接显著差异的基因在生存分析方面也具有更好的性能。总之，该文提出基于中值的JS散度可变剪接差异分析方法，将为进一步揭示可变剪接在癌症中的机制奠定基础。     

Distributed timeslot allocation with crossed slots in CDMA‐TDD systems

Code division multiple access system with time division duplex (CDMA‐TDD) is a promising solution to cope with traffic asymmetry of downlink (DL) and uplink (UL) in multimedia services. When a rate of asymmetry is different in each cell, CDMA‐TDD system may employ crossed slots, where a timeslot is used for different links in cells. However, it may suffer from base station (BS)‐to‐BS and mobile station (MS)‐to‐MS interference problem. Zone division scheme is an efficient way to tackle the crossed slot interference by dividing a cell into inner and outer zones and restricting communication in crossed slots only to inner zone. In this paper, we propose distributed crossed slot resource allocation with zone division in multi‐cell CDMA‐TDD system. Two conditions for crossed slot resource allocation are defined and the bound on the size of inner zone is analyzed mathematically based on the conditions. Relationship between the capacity of crossed slot and the size of inner zone is also analyzed. Then, numerical results of the mathematical analysis are presented; showing that the proposed crossed slot allocation is effective for traffic asymmetry problem. Copyright © 2009 John Wiley & Sons, Ltd.     

Network Performance Analysis of TCP-Based 3GPP LTE Time Division Duplex Systems

This paper deals with the determination of downlink (DL) and uplink (UL) channel split ratio for time division duplex (TDD) based long term evolution (LTE) networks. In a TDD system, UL and DL transmissions are carried out at different time intervals, but share the same frequency band. The TDD framing in LTE is adaptive in the sense that the DL to UL bandwidth ratio may vary with time. This paper proposes an adaptive split ratio (ASR) scheme for LTE networks to automatically adjust the bandwidth ratio of DL to UL, according to the current traffic profile, wireless interference, and transport layer parameters. This provides the maximum aggregate throughput in LTE systems. The performance analysis shows that ASR scheme outperforms static allocation in terms of higher aggregate throughput and better adaptively to network dynamics. Further, it is also observed that the ASR scheme performs well for LTE, compared to worldwide interoperability for microwave access (WiMAX) system.     

基于直角棱镜的气体传感器在能见度测量中的应用

用基于两个相同直角棱镜构成的气室,以不同的灵敏度分时测量气室的输出光强度,来测定大气消光系数,再根据科施米德(Koschmieder)定律计算大气能见度。测试结果表明,用基于直角棱镜的气室测量的数值与直接透射法所测的数值具有很好的相关性,相关系数为0.98;直角棱镜底面的轻度污脏对测量的影响可不考虑,该方法抵抗环境污染影响的能力较强,提高了长期可靠性。气室输出光束被聚焦后,用光纤束接收并传输到光电探测器,有效抑制了旁轴光束的干扰,光纤分布的不均匀性产生的附加误差小于2.0%。将暴露大气中的光学元件加热,控制了结露现象产生的影响。     

A Partial CSI Estimation Approach for Downlink FDD massive-MIMO System with Different Base Transceiver Station Topologies

Massive multiple-input multiple-output (massive-MIMO) is a promising technology for next generation wireless communications systems due to its capability to increase the data rate and meet the enormous ongoing data traffic explosion. However, in non-reciprocal channels, such as those encountered in frequency division duplex (FDD) systems, channel state information (CSI) estimation using downlink (DL) training sequence is to date very challenging issue, especially when the channel exhibits a shorter coherence time. In particular, the availability of sufficiently accurate CSI at the base transceiver station (BTS) allows an efficient precoding design in the DL transmission to be achieved, and thus, reliable communication systems can be obtained. In order to achieve the aforementioned objectives, this paper presents a feasible DL training sequence design based on a partial CSI estimation approach for an FDD massive-MIMO system with a shorter coherence time. To this end, a threshold-based approach is proposed for a suitable DL pilot selection by exploring the statistical information of the channel covariance matrix. The mean square error of the proposed design is derived, and the achievable sum rate and bit-error-rate for maximum ratio transmitter and regularized zero forcing precoding is investigated over different BTS topologies with uniform linear array and uniform rectangular array. The results show that a feasible performance in the DL FDD massive-MIMO systems can be achieved even when a large number of antenna elements are deployed by the BTS and a shorter coherence time is considered.

     

Performance analysis of load balancing in OFDMA cellular networks with inter‐cell relay

To balance and improve the resource utilization of the orthogonal frequency division multiple access (OFDMA) cellular networks, we switch parts of the edge users in overloaded cell to the adjacent light‐loaded cells by using the inter‐cell relay. The efficiency of traditional load balancing method based on the cell switching is low and in some cases, will occur the collision load problem. In this paper, we propose a new load balancing scheme based on inter‐cell relay in downlink OFDMA cellular networks. Besides, we put forward a new spectrum division scheme to reduce interference and improve spectrum efficiency. According to the formulas derived from the model we established, we can obtain the signal interference ratio and further to calculate the amount of remaining subcarrier and the throughput of the system. Finally, through numerical calculation and simulation, the result shows that the load balancing and spectrum division schemes can remit the resource stress of the overloaded cell and improve the spectrum utilization in adjacent cells.