To compress screen image sequence in real-time remote and interactive applications,a novel compression method is proposed.The proposed method is named as CABHG.CABHG employs hybrid coding schemes that consist of intra...To compress screen image sequence in real-time remote and interactive applications,a novel compression method is proposed.The proposed method is named as CABHG.CABHG employs hybrid coding schemes that consist of intra-frame and inter-frame coding modes.The intra-frame coding is a rate-distortion optimized adaptive block size that can be also used for the compression of a single screen image.The inter-frame coding utilizes hierarchical group of pictures(GOP) structure to improve system performance during random accesses and fast-backward scans.Experimental results demonstrate that the proposed CABHG method has approximately 47%-48% higher compression ratio and 46%-53% lower CPU utilization than professional screen image sequence codecs such as TechSmith Ensharpen codec and Sorenson 3 codec.Compared with general video codecs such as H.264 codec,XviD MPEG-4 codec and Apple's Animation codec,CABHG also shows 87%-88% higher compression ratio and 64%-81% lower CPU utilization than these general video codecs.展开更多
The hierarchical BiOCl_(x)Br_(1–x)was synthesized by a simple solvothermal method.The samples were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),UV-visible diffuse reflect...The hierarchical BiOCl_(x)Br_(1–x)was synthesized by a simple solvothermal method.The samples were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),UV-visible diffuse reflectance spectroscopy(UV-vis DRS)and Brunauer-Emmett-Teller adsorption method.Compared to pure BiOCl or BiOBr,the BiOCl_(x)Br_(1–x)solid solution has enhanced photocatalytic degradation activity for rhodamine B.This phenomenon can be explained to the hierarchical structure,lager specific surface area and appropriate energy gap of the obtained BiOCl_(x)Br_(1–x)solid solution.The renewability and stability of photocatalyst were determinated and a possible mechanism of photocatalytic degradation was also proposed.展开更多
现有大跨径桥梁有限元模型修正(finite element model updating,FEMU)方法一般未考虑运营荷载对结构动力特性的影响,导致修正后模型的参数变异性大。鉴于此,提出了一种考虑运营荷载的层次贝叶斯有限元模型修正方法,该方法包含考虑温度...现有大跨径桥梁有限元模型修正(finite element model updating,FEMU)方法一般未考虑运营荷载对结构动力特性的影响,导致修正后模型的参数变异性大。鉴于此,提出了一种考虑运营荷载的层次贝叶斯有限元模型修正方法,该方法包含考虑温度和交通荷载的概率参数修正、概率响应预测和结构状态评估。首先,根据监测数据的相关性分析结果确定了计算理论频率时需要考虑的荷载。随后,建立了温度-弹性模量线性关系,并基于动态称重(weigh-in-motion,WIM)数据,提出一种车辆荷载估计方法,以在有限元模型中定量考虑运营荷载对结构频率的影响。同时,引入两阶段马尔科夫链蒙特卡洛(Markov chain Monte Carlo,MCMC)采样方法和响应面代理模型,以提高概率模型修正的计算速率。该方法在一座采集了两年监测数据的大跨径拱桥上得到了验证。结果表明,在考虑运营荷载、参数不确定性和建模误差后,实测频率基本处于预测频率的95%置信区间内。最后,基于实测响应和预测响应置信区间提出了一个结构状态指标,并利用该指标检测出该桥的路面铺装更换过程。展开更多
基于本地化差分隐私多关系表示上的Star-JOIN查询已得到研究者广泛关注.现有基于OLH机制与层次树结构的Star-JOIN查询算法存在根节点泄露隐私风险、τ-截断机制没有给出如何选择合适τ值等问题.针对现有算法存在的不足,提出一种有效且...基于本地化差分隐私多关系表示上的Star-JOIN查询已得到研究者广泛关注.现有基于OLH机制与层次树结构的Star-JOIN查询算法存在根节点泄露隐私风险、τ-截断机制没有给出如何选择合适τ值等问题.针对现有算法存在的不足,提出一种有效且满足本地化差分隐私的Star-JOIN查询算法LPRR-JOIN(longitudinal path random response for join).该算法充分利用层次树的纵向路径结构与GRR机制,设计一种纵向本地扰动算法LPRR,该算法以所有属性纵向路径上的节点组合作为扰动值域.每个用户把自身元组映射到相应节点组合中,再利用GRR机制对映射后的元组进行本地扰动.为了避免事实表上存在的频率攻击,LPRR-JOIN算法允许每个用户利用阈值τ本地截断自身元组个数,大于τ条元组删减、小于τ条元组补充.为了寻找合适的τ值,LPRR-JOIN算法利用τ-截断带来的偏差与扰动方差构造总体误差函数,通过优化误差目标函数获得τ值;其次结合用户分组策略获得τ值的总体分布,再利用中位数获得合适的τ值.LPRR-JOIN算法与现有算法在3种多关系数据集上进行比较,实验结果表明其响应查询算法优于同类算法.展开更多
为了在视域(field of view,FOV)不同的条件下实现对数量时变的不确定目标的最优跟踪,提出一种高斯混合概率假设密度(Gaussian mixture probability hypothesis density,GM-PHD)滤波器的去相关算术平均(arithmetic average,AA)融合算法...为了在视域(field of view,FOV)不同的条件下实现对数量时变的不确定目标的最优跟踪,提出一种高斯混合概率假设密度(Gaussian mixture probability hypothesis density,GM-PHD)滤波器的去相关算术平均(arithmetic average,AA)融合算法。鉴于多目标AA融合被分解为多组单目标分量的合并,先通过重构贝叶斯融合推导出最优去相关估计融合,后将其用作单目标分量的合并方法。由于推导的去相关估计融合需要先验估计,设计了一个包含主滤波器的分层结构,以自动提供需要的先验估计。为了解决不同FOV导致的目标势低估问题,融合节点利用FOV补偿单目标分量的权重。仿真结果证实了提出的算法在各种场景中的最优性,提升了多目标跟踪的精度。展开更多
基金Project(60873230) supported by the National Natural Science Foundation of China
文摘To compress screen image sequence in real-time remote and interactive applications,a novel compression method is proposed.The proposed method is named as CABHG.CABHG employs hybrid coding schemes that consist of intra-frame and inter-frame coding modes.The intra-frame coding is a rate-distortion optimized adaptive block size that can be also used for the compression of a single screen image.The inter-frame coding utilizes hierarchical group of pictures(GOP) structure to improve system performance during random accesses and fast-backward scans.Experimental results demonstrate that the proposed CABHG method has approximately 47%-48% higher compression ratio and 46%-53% lower CPU utilization than professional screen image sequence codecs such as TechSmith Ensharpen codec and Sorenson 3 codec.Compared with general video codecs such as H.264 codec,XviD MPEG-4 codec and Apple's Animation codec,CABHG also shows 87%-88% higher compression ratio and 64%-81% lower CPU utilization than these general video codecs.
基金Project(2016TP1007)supported by the Hunan Provincial Science and Technology Plan Project,China
文摘The hierarchical BiOCl_(x)Br_(1–x)was synthesized by a simple solvothermal method.The samples were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),UV-visible diffuse reflectance spectroscopy(UV-vis DRS)and Brunauer-Emmett-Teller adsorption method.Compared to pure BiOCl or BiOBr,the BiOCl_(x)Br_(1–x)solid solution has enhanced photocatalytic degradation activity for rhodamine B.This phenomenon can be explained to the hierarchical structure,lager specific surface area and appropriate energy gap of the obtained BiOCl_(x)Br_(1–x)solid solution.The renewability and stability of photocatalyst were determinated and a possible mechanism of photocatalytic degradation was also proposed.
文摘现有大跨径桥梁有限元模型修正(finite element model updating,FEMU)方法一般未考虑运营荷载对结构动力特性的影响,导致修正后模型的参数变异性大。鉴于此,提出了一种考虑运营荷载的层次贝叶斯有限元模型修正方法,该方法包含考虑温度和交通荷载的概率参数修正、概率响应预测和结构状态评估。首先,根据监测数据的相关性分析结果确定了计算理论频率时需要考虑的荷载。随后,建立了温度-弹性模量线性关系,并基于动态称重(weigh-in-motion,WIM)数据,提出一种车辆荷载估计方法,以在有限元模型中定量考虑运营荷载对结构频率的影响。同时,引入两阶段马尔科夫链蒙特卡洛(Markov chain Monte Carlo,MCMC)采样方法和响应面代理模型,以提高概率模型修正的计算速率。该方法在一座采集了两年监测数据的大跨径拱桥上得到了验证。结果表明,在考虑运营荷载、参数不确定性和建模误差后,实测频率基本处于预测频率的95%置信区间内。最后,基于实测响应和预测响应置信区间提出了一个结构状态指标,并利用该指标检测出该桥的路面铺装更换过程。
文摘基于本地化差分隐私多关系表示上的Star-JOIN查询已得到研究者广泛关注.现有基于OLH机制与层次树结构的Star-JOIN查询算法存在根节点泄露隐私风险、τ-截断机制没有给出如何选择合适τ值等问题.针对现有算法存在的不足,提出一种有效且满足本地化差分隐私的Star-JOIN查询算法LPRR-JOIN(longitudinal path random response for join).该算法充分利用层次树的纵向路径结构与GRR机制,设计一种纵向本地扰动算法LPRR,该算法以所有属性纵向路径上的节点组合作为扰动值域.每个用户把自身元组映射到相应节点组合中,再利用GRR机制对映射后的元组进行本地扰动.为了避免事实表上存在的频率攻击,LPRR-JOIN算法允许每个用户利用阈值τ本地截断自身元组个数,大于τ条元组删减、小于τ条元组补充.为了寻找合适的τ值,LPRR-JOIN算法利用τ-截断带来的偏差与扰动方差构造总体误差函数,通过优化误差目标函数获得τ值;其次结合用户分组策略获得τ值的总体分布,再利用中位数获得合适的τ值.LPRR-JOIN算法与现有算法在3种多关系数据集上进行比较,实验结果表明其响应查询算法优于同类算法.
文摘为了在视域(field of view,FOV)不同的条件下实现对数量时变的不确定目标的最优跟踪,提出一种高斯混合概率假设密度(Gaussian mixture probability hypothesis density,GM-PHD)滤波器的去相关算术平均(arithmetic average,AA)融合算法。鉴于多目标AA融合被分解为多组单目标分量的合并,先通过重构贝叶斯融合推导出最优去相关估计融合,后将其用作单目标分量的合并方法。由于推导的去相关估计融合需要先验估计,设计了一个包含主滤波器的分层结构,以自动提供需要的先验估计。为了解决不同FOV导致的目标势低估问题,融合节点利用FOV补偿单目标分量的权重。仿真结果证实了提出的算法在各种场景中的最优性,提升了多目标跟踪的精度。
