5DXC FTIR宏指令研究聚氨酸化学反应

利用Ｎｉｃｏｌｅｔ ５ＤＸＣ ＦＴＩＲ操作系统听提供的宏编辑程序，论述了自定义宏指令在聚氨酯化学反应动力学及结构分析研究中的应用。表明，运用５ＤＸＣ宏指令，简单易行，测量准确，工作效率高，可以满足数分钟内完成的聚氨酯聚合反应动力学研究的需要。借助宏指令发现聚氨酯聚合反应在一定反应程度范围内服从二级反应动力学，催化剂的性质影响二级反应动力学的适用范围。随着聚合反应的进行，聚氨酯酰胺Ⅱ谱带呈阶跃式由１     

5DXC FTIR宏指令研究聚氨酯化学反应

利用ＮｉｃｏｌｅｔＳＤＸＣＦＴＩＲ操作系统中提供的宏编辑程序，论述了自定义宏指令在聚氨酯化学反应动力学及结构分析研究中的应用。结果表明，运用ＳＤＸＣ宏指令，简单易行，测量准确，工作效率高，可以满足数分钟内完成的聚氨酯聚合反应动力学研究的需要。借助宏指令发现聚氨酯聚合反应在一定反应程度范围内服从二级反应动力学，催化剂的性质影响二级反应动力学的适用范围。随着聚合反应的进行，聚氨酯酸胺Ⅱ谱带呈阶跃式由１５２５．７ｃｍ－１移向１５３７．４ｃｍ－１。     

有限尺寸宏粒子空间电荷场研究

 用格林函数理论导出了圆柱对称系统中有限尺寸宏粒子一维和二维空间电荷场权函数的表达式，比较了有限尺寸宏粒子空间电荷场权函数与圆盘或圆环模型空间电荷场权函数的差别，得到了与圆盘或圆环模型空间电荷场权函数[1]不同的、更合理的计算结果。并用这两种空间电荷场权函数模拟了螺旋线行波管中的注波互作用过程，得到了其输出功率曲线，表明了用有限尺寸宏粒子计算的互作用输出功率比圆盘或圆环模型计算的输出功率饱和位置提前，饱和值增加。     

基于模式相关性的多视点视频编码宏块模式快速选择算法

针对多视点视频编码计算量大的问题,提出了一种多视点视频编码快速宏块模式选择算法.详细分析了多视点视频编码校验模型的宏块模式选择结果的分布特性以及率失真特性,提出了宏块模式相关性和模式聚集度的概念.对测试序列的宏块模式相关性分析表明当前宏块的最优模式和大多数相邻宏块的最优模式相同.从相邻宏块区域聚集度的角度分析了当前宏块模式预测准确度.在算法实现中采用相邻宏块的率失真代价均值形成的阈值条件决定是否进行全搜索.实验结果表明该算法在保持编码率失真性能的基础上,能提高多视点视频编码的速度2.43～4.08倍.     

条纹相机系统在激光脉冲整形测量中的应用

针对采用脉冲堆积法进行激光脉冲整形后获取的宏脉冲,介绍了基于条纹相机观测其纵向分布的基本原理。阐述了测量系统中的硬件配置功能以及脉冲堆积原理,并描述了使用条纹相机专用软件测量激光脉冲的详细步骤和操作界面。研究了测量系统中时序控制的调试对观测脉冲堆积后的宏脉冲的影响并给出了测量结果和测量误差分析。结果表明:采用脉冲堆积法所获得的激光脉冲整形效果非常理想,整形前激光脉冲的半高全宽值约为3.82 ps,整形后约为15.3 ps,且平顶部分的脉宽为11.5 ps,上升沿和下降沿均为1.9 ps。     

基于平均预测残差的H.264宏块层码率控制算法

针对H.264码率控制模型的“蛋鸡悖论”，提出一种用平均预测残差来表示当前宏块编码复杂度的算法。首先根据各个宏块不同的编码复杂度进行准确的比特分配,然后根据改进的二次R-D预测模型来计算宏块的量化参数，并进行率失真优化,最后进行码率控制模型系数的更新。将算法在JM8.6平台上进行实验，结果显示，在相同码率下，本文算法的平均控制精度比JVT-H017提高0165 kb/s，平均PSNR比JVT-H017提高013 dB，表明本算法能够更准确控制码率并获得更高质量的主观视觉。     

精密宏微复合绝对式光栅尺设计与研究

通过对光栅尺原理的研究,设计一种宏微复合切换测量模式,利用增量码进行低精度测量,绝对码进行高精度测量。采用增量方式采集莫尔条纹的高速性,解决高精度绝对位置采集的低速性,实现宏微复合的高速与高精度的测量。实验证明,高精度低速绝对位置测量过程中测量精度可达0.6 m,在测量中使用新型高速与低速的变速切换测量方式,综合测量速度最高可以达到2 m/s。     

单模光纤宏弯损耗的温度响应特性

为了实现光纤宏弯温度传感,对单模光纤宏弯损耗的温度响应特性进行了理论与实验研究.理论上对单模光纤宏弯损耗理论公式进行了温度修正.基于该公式模拟了波长、弯曲半径以及温度对纤芯-无限包层结构单模光纤宏弯损耗性能的影响.设计制作了一种带吸收层和镍保护层的单模光纤宏弯温度传感探头并进行了温度传感性能实验测试.结果表明:纤芯-无限包层结构单模光纤宏弯损耗对弯曲半径、波长和温度变化较为敏感,与温度之间的响应呈线性,该探头的温度分辨率为0.4℃;通过减小弯曲半径和提高光源波长,可进一步提高其温度灵敏度和分辨率.该结构光纤可近似看作纤芯-无限包层结构光纤,用于开发光纤宏弯温度传感器.     

评《高稳定度测微光度计稳压电源的研制和使用》

在《首届全国光谱仪器维修与改进学术研讨会》上,宏明无线电器材总厂王熙敬宣读了一篇论文《高稳定度测微光度计稳压电源的研制和使用》。会上虽然反复提到了"周高工",但只字未提周高工的专利权和著作权。1990年3月左右,王熙敬及其实验室主任向我提出:由于科研工作急需,要"购买"高稳定度的稳压电源,并提出将我们制造的TV-I型稳压器放在他厂现场考验。于是我从北京带了一台仪器到成都宏明无线电器材总厂王的实验室考验。现场测量表明,     

聚酰亚胺涂覆的光纤宏弯温度传感器

为了提高光纤宏弯温度传感器的性能,提出了一种基于聚酰亚胺(PI)涂覆的新颖光纤宏弯温度传感器。利用基于纤芯-包层-无限涂覆层结构的光纤弯曲损耗-温度测量方法确定了传感器的光纤弯曲半径,将PI薄膜涂覆在1060-XP光纤包层外获得了新型的光纤宏弯温度传感器。该传感器的温度传感实验结果表明,PI涂覆不仅能提升光纤的机械性能和耐热性,还可实现温度灵敏度和温度测量分辨能力的显著提高。该新颖的光纤宏弯温度传感器可实现-20～100℃的宽温测量范围,温度灵敏度为0.072 dB/℃,分辨能力为0.14℃。与其他光纤宏弯温度传感器相比,所设计的传感器的温度传感性能显著提高。     

A fuzzy admission control scheme for high quality video delivery over underlay cognitive radio

In much of the traditional tight admission control algorithms for video cognitive users in cognitive networks, cognitive users are admitted sequentially based on the strict quality of service and interference constraints imposed on the cognitive and primary users respectively. The sequential admittance of cognitive users may impose some form of the queuing delay for time-sensitive cognitive users which may be unacceptable. On the other hand, traditional admission control schemes do not consider the quality of experience (QoE) of video users for admitting newly incoming ones. For addressing these issues and obtaining a more flexible quality-centric admission control policy by which the admission system can admit eligible cognitive users in parallel, and to cope with uncertainties in the acceptable levels of the video quality for different cognitive users (which may use different software/hardware with different capabilities) and interference levels imposed on the primary users, a soft admission control (SAC) technique (named FQAC) is proposed by which the admission probability level for the parallel cognitive users can intelligently be controlled based on some linguistic input variables. Numerical analysis has been performed to validate the efficiency of the proposed quality-aware SAC mechanism.     

On the performance of a virtual user pairing scheme to efficiently utilize the spectrum of unpaired users in NOMA

This paper evaluates the performance of a virtual user pairing scheme that efficiently utilizes the spectrum of unpaired users in non-orthogonal multiple access (NOMA), termed as VP-NOMA. The scheme aims at utilizing the frequency bands of those users which remain unpaired due to the non-uniform distribution of users in a cellular area. We consider a case where the cell edge users are more than the cell center users, so that complete one-to-one correspondence does not exist between all cell center and cell edge users to be accommodated/paired using conventional NOMA (C-NOMA) user pairing. Thus, some cell edge users remain unpaired, and are served using conventional multiple access (OMA) schemes. In such scenario, VP-NOMA pairs a single cell center user with two or more clustered (closely located) cell edge users over non-overlapping frequency bands, thus enabling the cell center user to efficiently use the frequency bands of these previously unpaired cell edge users. Performance of VP-NOMA in terms of ergodic sum capacity (ESC), outage probability (OP), and outage sum capacity (OSC), is analyzed through comprehensive mathematical derivations and simulations for a generalized system model. Moreover, the mathematical analysis is validated through close concordance between analytical and simulation results of ESC, OP, and OSC.     

Proactive channel access in dynamic spectrum networks

Open Spectrum systems allow fast deployment of wireless technologies by reusing under-utilized pre-allocated spectrum channels, all with minimal impact on existing primary users. However, existing proposals take a reactive sense-and-avoid approach to impulsively reconfigure spectrum usage based solely on the latest observations. This can result in frequent disruptions to operations of both primary and secondary users. In this paper, we propose a proactive spectrum access approach where secondary users utilize past channel histories to make predictions on future spectrum availability, and intelligently schedule channel usage in advance. We propose two channel selection and switching techniques to minimize disruptions to primary users and maintain reliable communication at secondary users. Both simulation and testbed results show that the proactive approach effectively reduces the interferences to primary users by up to 30%, and significantly decreases throughput jitters at secondary users.     

A novel blind spatial-based random access to pilots (BSB-RAP) in overloaded massive MIMO systems

In this study, to increase the success rate of active user admission in overloaded massive multi-input multi-output (MIMO) systems, a new spatially based random access to pilots (RAP) is proposed to assign orthogonal pilots to the users requesting network access. Therefore, by increasing the acceptance rate of users in a cell, this approach reduces the training overhead and waste of resources. In the massive MIMO for crowd scenarios, the main issue is the limited number of available orthogonal pilots employed by the users in the channel estimation process. This novel approach as spatially based random access enables us to have more connected users during every coherence interval (CI) despite the mentioned limitation. Intrinsic angular domain sparsity of massive MIMO channels and the sporadic traffic of users can help us obtain the spatial features of active UEs in a blind continuous compressed sensing (CCS) approach. Proposed approach is to use a continuous compressed sensing technique based on a prior optimization that provides users’ angle of arrival (AoA) and an innovative space-based RAP protocol to assign orthogonal pilots to active users in coherent transmission. Unlike the previous works, this strategy does not need to limit the number of users to the number of available orthogonal pilots due to the employed spatial degrees of freedom.     

Resource allocation for LTE-based cognitive radio network with queue stability and interference constraints

We consider the problem of interference management and resource allocation in a cognitive radio network (CRNs) where the licensed spectrum holders (primary users) share their spare capacity with the non-licensed spectrum holders (secondary users). Under such shared spectrum usage the transmissions of the secondary users should have a minimal impact on the quality of service (QoS) and the operating conditions of the primary users. Therefore, it is important to distinguish the two types of users, and formulate the problem of resource allocation considering hard restrictions on the user-perceived QoS (such as packet end-to-end delay and loss) and physical-layer channel characteristics (such as noise and interference) of the primary users. To achieve this goal, we propose to assign the bandwidth and transmission power to minimize the total buffer occupancy in the system subject to capacity constraints, queue stability constraints, and interference requirements of the primary users. We apply this approach for resource allocation in a CRN built upon a Third Generation Partnership Project (3GPP) long-term evolution (LTE) standard platform. Performance of the algorithm is evaluated using simulations in OPNET environment. The algorithm shows consistent performance improvement when compared with other relevant resource allocation techniques.     

Optimal downlink power allocation in cellular networks

In this paper, we introduce a novel approach for power allocation in cellular networks. In our model, we use sigmoidal-like utility functions to represent different users’ modulation schemes. Each utility function is a representation of the probability of successfully transmitted packets per unit of power consumed by a user, when using a certain modulation scheme. We consider power allocation with utility proportional fairness policy, where the fairness among users is in utility percentage i.e. percentage of successfully transmitted packets of the corresponding modulation scheme. We formulate our power allocation optimization problem as a product of utilities of all users and prove that it is convex and therefore the optimal solution is tractable. We present a distributed algorithm to allocate base station powers optimally with priority given to users running lower modulation schemes while ensuring non-zero power allocation to users running higher modulation schemes. Our algorithm prevents fluctuation in the power allocation process and is capable of traffic and modulation dependent pricing policy. This can be used to flatten traffic and decrease the service price for users. We also compare our results with a benchmark algorithm and show that our algorithm performs better in allocating powers fairly to all users without dropping any user in order to maximize performance.     

社交网络用户浏览轨迹信息隐私保护方法仿真

随着网络应用的广泛普及,QQ、微信、YY语音、陌陌等社交软件走进千家万户,但社交网络用户浏览轨迹信息隐私保护问题也随之而来。由于社交网络平台安全机制存在漏洞,抵御网络攻击性能不强,使社交网络用户信息纷纷泄露。针对问题根源,提出ACP用户隐私信息防护系统,建立社交网络用户真空登陆模块(VM)、通讯信息密码文模块(RDT)及信息储存保护墙模块(LDM)一体化ACP用户隐私信息防护系统,从根源保护社交网络用户浏览轨迹信息的隐私安全。通过数据模拟仿真实验证明提出的ACP用户隐私信息防护系统,对社交网络用户浏览轨迹信息隐私保护具有可用性与有效性。     

语后聋人工耳蜗使用者电刺激听觉部位音调感知研究

系统地研究了人工耳蜗植入者的电刺激听觉部位音调感知,全面地探讨了部位音调感知与人工耳蜗植入者言语识别和音乐感知的关系。4位成人语后聋人工耳蜗植入者参与了该研究。通过电极音调排序测试度量植入者的部位音调感知能力。言语能力测试和音乐音高分辨测试分别用米考察植入者的言语识别和音乐感知能力。结果显示,随着电极刺激部位从蜗尖移向蜗底,所有受试者均可获得从"低"到"高"的音调感知变化,但个体差异较大。受试者的言语识别结果与其电刺激听觉部位音调感知能力相关,但受到天花板效应影响,对应关系并不明显。受试者的音乐音高分辨成绩与其电刺激听觉部位音调感知能力呈较好的对应关系。结果表明,当前人工耳蜗声音编码策略所传递的声信号特征已可使植入者获得良好的言语识别效果;且安静环境下言语识别对植入者的部位音调感知能力要求不高。但当前的声音编码策略并未能有效对音乐信号进行编码;植入者在理解音乐这类复杂声信号时,其电刺激听觉部位音调感知能力一定程度决定了其听音效果。      

Spectral efficiency maximization for IRS-assisted wireless communication in cognitive radio networks

In this paper, we consider the Intelligent reflecting surface (IRS)-assisted cognitive radio (CR) network, in which the IRS is applied to improve the spectral efficiency of secondary users. In specific, the advantages of applying IRS is double: it can not only improve the transmission rate of the secondary users, but also reduce the interference from the secondary users to the primary users, which allow the secondary users to increase the transmission power correspondingly. The original problem is formulated by simultaneously consider the maximum power limitation of the secondary users and the Quality of Service (QoS) requirement of the primary users, which expressed by the interference temperature (IT). The formulated problem is non-convex and difficult to solve directly. We apply the alternating optimization (AO) algorithm to split the original problem into two sub-problems. For the first sub-problem, we transform it into a convex problem and for the second sub-problem, we use the successive convex approximation method to obtain the corresponding results. The simulation experiments show that the performance of our proposed scheme is better than existing schemes.     

Place-pitch perception in electrical hearing with post-lingually deafened cochlear implant users

The main goal of this study was to systematically investigate place-pitch perception in electrical hearing and the relative relationship between place-pitch perception ability,speech understanding and musical pitch discrimination by cochlear implant(CI) users.Electrode pitch ranking test was carried out to evaluate the place-pitch perception ability of CI users. Four post-lingually deafened CI users were recruited.They also participated in the speech recognition test and musical pitch discrimination test.Results showed that place pitch were generally ordered from apical to basal electrodes.The apical electrodes were judged lower in pitch than basal electrodes.Large individual difference was found.Comparing pitch and speech performance,the speech recognition result was related to the place-pitch perception ability of CI users,but this relationship was limited by the ceiling effects.However,a correlative relationship was found between musical pitch discrimination result and place-pitch ability of CI users.It indicated that the current signal processing of CI system can provide sufficient information for speech understanding but not for music perception of CI users.To a certain extent,music perception of CI users was determined by their place-pitch abilities.