面向VR应用的花卉植物物理渲染技术研究与实现

花卉植物高真实感的仿真交互是目前虚拟植物可视化研究的一个重要方向。随着虚拟现实技术的普及,越来越多的应用采用了VR头戴设备的呈现方式。VR系统需要高度真实的沉浸感画面,通用的植物建模和图形引擎渲染功能已不能满足该需求。该文通过分析光照原理并融合基于物理的渲染技术,提出基于双向散射分布函数BSDF的花卉植物高度真实感的物理渲染算法,利用ShaderLab,对几种盆栽花卉植物在光照下进行仿真,并对融合算法做优化处理。针对VR头盔设备HTC Vive的成像效果,对图像进行扭曲变形优化,使画面更符合人眼双目立体视觉成像效果,增强系统沉浸感。最后基于该方法设计并实现了一个头盔式VR花卉植物仿真模拟系统,获得了逼真的场景漫游体验效果。     

Distinguishing social contacts and pass-by contacts in DTN routing

Smallcells deployment in heterogeneous networks (HetNets) introduce uplink (UL) downlink (DL) asymmetry, backhaul bottleneck, cell load imbalances, increased core network signaling, interference and mobility management problems. In order to address these issues, concept of dual connectivity has been introduced in 3rd generation partnership project (3GPP) release 12. In dual connectivity, a given user equipment can consume radio resources of at least two different network points connected through non-ideal backhaul for spectrum aggregation and cooperative access mechanisms in dense 5G HetNets. Alternatively, another concept of downlink and uplink decoupling (DUDe) has also been recently introduced in 3GPP to improve uplink performance, load balancing and cell capacity. In order to take advantage of the strengths of these latest developments, this paper significantly advances prior work by analyzing K-tier 5G HetNets having dual connectivity and decoupled access (joint DUDe dual-connectivity) for spectrum aggregation in UL and DL. In the preceding works, K-tiers as per present-day heterogeneity, uplink power control and receiver noise have not been considered for joint DUDe dual-connectivity. With the use of stochastic geometry, we have developed closed form solutions for association, coverage and outage probabilities along with average throughput for joint DUDe dual-connectivity by considering uplink power control, receiver noise and K-tiers of HetNets. The resultant performance metrics are evaluated in terms of achieved gains over conventional downlink received power access policies. Results show that cell association technique based on joint DUDe dual-connectivity can significantly improve load balancing, mobility management and UL performance for forthcoming 5G HetNets.     

两种水过滤形式在纺织厂空调室的应用对比

纺织厂都采用喷水室空调,空调室的用水量很大。为了节能,喷水室采用循环水,就需要过滤掉水中的杂质。通过测试经过转笼式水过滤器和砂石过滤水池前后的空调用水的水质情况,过滤后的水硬度在150 mg/L~450 mg/L之间,水的硬度在硬水的范围内,纺织厂对水质的要求不是太高,此范围基本符合用水要求。根据水中溶解固形物(重量法)的测定原理,测水中悬浮物含量,分别计算出转笼式过滤器和砂石过滤水池的过滤效率为83.7%、79.9%。对于一个空调室全年的耗能量计算,转笼式水过滤器的耗电费用是砂石过滤水池耗水费用的6倍。     

基于android和云平台的智能家居系统设计与实现

为解决智能家居系统大规模数据的存储、管理及移动终端的可靠接入等问题,本文设计了一种基于嵌入式家庭网关、Android和云平台服务的智能家居系统。利用极光云推送服务及时将家庭的异常报警信息推送到手机客户端,系统还提供了视频监控功能,用户随时随地通过手机查看家庭动态。当监测异常时会自动拍照记录异常场景,并上传至yeelink物联网云平台,进行图像云存储。另外通过手机客户端可以查看所选时间范围内的报警图像,随时掌控家庭生活。     

Price‐based interference management in dense femtocell systems

Femtocell technology has been drawing considerable attention as a cost‐effective means of improving cellular coverage and capacity. However, under co‐channel deployment, femtocell system in dense environment may incur high uplink interference to existing macrocells and experiences strong inter‐cell interference at the same time. To manage the uplink interference to macrocell, as well as the inter‐cell interference, this paper proposes a price‐based uplink interference management scheme for dense femtocell systems. Specifically, on the one hand, to guarantee the macrocell users' quality of service, the macrocell base station prices the interference from femtocell users (FUEs) subject to a maximum tolerable interference power constraint. On the other hand, the inter‐cell interference is also taken into consideration. Moreover, a Stackelberg game model is adopted to jointly study the utility maximization of the macrocell base station and FUEs. Then, in order to reduce the amount of information exchange, we design a distributed power allocation algorithm for FUEs. In addition, admission control is adopted to protect the active FUEs' performance. Numerical results show that the price‐based interference management scheme is effective. Meanwhile, it is shown that the distributed power allocation combined with admission control is capable of robustly protecting the performance of all the active FUEs. Copyright © 2013 John Wiley & Sons, Ltd.     

MIMO系统中一种自适应的迭代检测译码算法

针对常用的非穷尽列表形式后验概率检测算法直接采用恒定且较大的列表长度,导致列表冗余度大的问题,该文提出了一种自适应长度的列表球形译码算法(Adaptive Size List Sphere Decoding, ASLSD)。在算法中通过更新检测半径和设置停止条件,使检测列表长度可随信噪比和迭代次数自适应变化。而且通过将列表操作与LSD (List Sphere Decoding)检测相结合,避免了符号序列在不同半径下的重复检测。仿真表明,在较小性能损失的前提下,该算法可以大大减小所需检测列表的长度,进而有效降低接收机的复杂度。     

隐埋层中二维效应对全耗尽SOI非对称HALO结构阈值电压的影响

在非对称HALO结构的全耗尽SOI二维阈值电压解析模型的基础上,对阈值电压受隐埋层中二维效应的影响进行了讨论.通过与一维模型的比较,说明在深亚微米SOI MOSFET器件中隐埋层的二维效应会导致器件提前出现短沟道效应.新模型结果与二维数值模拟软件MEDICI吻合较好.     

42"PDP平板显示器扫描驱动IC及其生产工艺的实现

在自主研发国内BCD高压工艺的同时,设计并实现了一款用于42″数字电视PDP平板显示屏的扫描驱动芯片.该芯片及其制作工艺不仅实现了Bipolar,CMOS和高压功率DMOS器件的良好兼容（BCD工艺）,而且采用工艺与电路设计互相匹配的交互方式完成了高低电平位移电路和高压输出驱动电路及其器件的设计,有效提高了芯片的性能,减小了芯片的面积.测试结果表明该芯片功能正常,性能良好,各项技术参数基本达到国外同类产品指标.在低压5V和高压160V的情况下工作,完全满足42″PDP显示系统的需求.     

喷雾清洗中微颗粒受到流体作用力的研究

对喷雾清洗过程中微颗粒所受到的流体力进行了研究.由于液滴撞击在平面上产生的不稳定流,无法用现有的层流作用力公式来预测颗粒所受到的作用力,本文采用了计算流体力学模拟的方法对流场分布进行了模拟,并且计算颗粒上相应受到的作用力.通过计算结果,讨论了影响颗粒清除效果的关键因素.研究表明,在微米尺度内,平面的可湿性质对液滴展开的初始阶段流场分布有显著影响,从而也大大影响了平面上颗粒所受到的作用力.此外,撞击在干燥表面时,颗粒受到的拖拽力会比撞击到湿表面上时大三个数量级以上.而在湿表面上时,提高撞击速度会比增大液滴大小来得更有效,主导颗粒去除的力为拖拽力.     

Improving the performance of polymer solar cells by altering polymer side chains and optimizing film morphologies

Two donor–acceptor (D–A) type conjugated polymers using dodecyl- and ethylhexyl-thiophene substituted benzo[1,2-b:4,5-b′]dithiophene (BDT-DDT and BDT-EHT, respectively) as donors and n-alkylthieno[3,4-c]pyrrole-4,6-dione (TPD) as acceptor were synthesized and characterized. The thiophene substituted BDT unit was recognized as a two-dimensional (2D) π-extended segment with high carrier mobility and TPD unit was a relatively strong electron-drawing acceptor, which could lead to deep-lying highest occupied molecular orbital (HOMO) levels of the polymers. The optical properties, electrochemical behavior, and charge carrier properties of the polymers were compared in parallel. The results indicated that ethylhexyl-substitution could optimize the polymer structures and properties. The bulk-heterojunction polymer solar cells (PSCs) based on the two polymers were fabricated and characterized. The devices based on ethylhexyl-substituted polymer showed better performance than that of dodecyl-substituted one. Further analysis proved that the improvement was mainly ascribed to the formation of well-defined nanostructures by using branched ethylhexyl side chains, which facilitated charge separation and transport in the bicontinous active layer. This study suggests that obtaining appropriate film morphology and phase separation by altering alkyl side chains is extraordinary important for high performance PSCs based on D–A type polymers.