在室内可见光通信中符号间干扰和噪声会严重影响系统性能,K均值(K-means)均衡方法可以抑制光无线信道的影响,但其复杂度较高,且在聚类边界处易出现误判。提出了改进聚类中心点的K-means(Improved Center K-means,IC-Kmeans)算法,通过随...在室内可见光通信中符号间干扰和噪声会严重影响系统性能,K均值(K-means)均衡方法可以抑制光无线信道的影响,但其复杂度较高,且在聚类边界处易出现误判。提出了改进聚类中心点的K-means(Improved Center K-means,IC-Kmeans)算法,通过随机生成足够长的训练序列,然后将训练序列每一簇的均值作为K-means聚类中心,避免了传统K-means反复迭代寻找聚类中心。进一步,提出了基于神经网络的IC-Kmeans(Neural Network Based IC-Kmeans,NNIC-Kmeans)算法,使用反向传播神经网络将接收端二维数据映射至三维空间,以增加不同簇之间混合数据的距离,提高了分类准确性。蒙特卡罗误码率仿真表明,IC-Kmeans均衡和传统K-means算法的误码率性能相当,但可以显著降低复杂度,特别是在信噪比较小时。同时,在室内多径信道模型下,与IC-Kmeans和传统Kmeans均衡相比,NNIC-Kmeans均衡的光正交频分复用系统误码率性能最好。展开更多
目的基于“紧急输血由急诊科授权医生启动,输血科15 min内发放不超过4 U O型未交叉配血悬浮红细胞”的单中心临床实践,了解该实践背景下紧急输O型未交叉配血悬浮红细胞策略的实施现状,为血液管理提供参考。方法回顾性分析2019年8月—202...目的基于“紧急输血由急诊科授权医生启动,输血科15 min内发放不超过4 U O型未交叉配血悬浮红细胞”的单中心临床实践,了解该实践背景下紧急输O型未交叉配血悬浮红细胞策略的实施现状,为血液管理提供参考。方法回顾性分析2019年8月—2024年4月四川大学华西医院紧急输O型血患者病例信息,包括申请紧急输血原因、输血申请送达输血科所需时间、输血科血液发放所需时间、患者输血前后总胆红素、间接胆红素、乳酸脱氢酶、患者血型、病情转归等。结果2019年8月—2024年4月本院申请紧急输O型血的患者有39例,共输注未经交叉配血的O型悬浮红细胞90 U。患者均为Rh(D)阳性,其中A型14例;B型6例;O型16例;AB型2例;暂无法定型1例,抗体筛查阳性2例,紧急输O型血的患者中车祸伤是主要原因,占46%(18/39),死亡率51.28%(20/39),死亡原因均为原发伤,无溶血性输血反应的临床指征:输血前后总胆红素(TBTL)、间接胆红素(IBIL)、乳酸脱氢酶(LDH)无统计学差异,P值均>0.05。患者从入院到输血科接收输血申请单和输血科从收到申请单到血液发放的中位时间分别为30.20 min和5.30 min。结论基于“紧急输血由急诊科授权医生启动,输血科15 min内发放不超过4 U O型未交叉配血悬浮红细胞”的单中心临床实践具有安全性,但申请紧急输O型血流程中在输血申请单送达输血科之前有优化空间。展开更多
The first path-independent insertion-loss（PILOSS） strictly non-blocking 4×4 silicon electro–optic switch matrix is reported. The footprint of this switch matrix is only 4.6 mm×1.0 mm. Using single-arm mod...The first path-independent insertion-loss（PILOSS） strictly non-blocking 4×4 silicon electro–optic switch matrix is reported. The footprint of this switch matrix is only 4.6 mm×1.0 mm. Using single-arm modulation, the crosstalk measured in this test is-13 dB --27 dB. And a maximum crosstalk deterioration of 6d B caused by two-path interference is also found.展开更多
In data streams or web scenarios at highly variable and unpredictable rates, a good join algorithm should be able to ＂hide＂ the delays by continuing to output join results. The non-blocking algorithms allow some tup...In data streams or web scenarios at highly variable and unpredictable rates, a good join algorithm should be able to ＂hide＂ the delays by continuing to output join results. The non-blocking algorithms allow some tuples to be flushed onto disk, with the goal of producing results continuously when data transmission is suspended. But state-of-the-art algorithms have trouble with the constraint of allocated memory. To make better use of memory, a novel non-blocking join algorithm based on hash-merge for improving query response times is proposed. The reduced data structure of in-memory tuples helps to improve memory utility. A replacement selection tree is applied to adjust memory by expanding or shrinking the size of the tree and separates one external join transaction into multi-subtasks. In addition, a cost model to estimate task output rate is proposed to select the in-disk portion that promises to produce the fastest results in the external join stage. Experiments show that the technique, with far less memory, delivers results faster than the three non-blocking join algorithms （ XJoin, HMJ and RPJ ） , with up to almost two-fold improvement in reliable network and one order of magnitude improvement in unreliable network in terms of the number of the reported tuples.展开更多
文摘在室内可见光通信中符号间干扰和噪声会严重影响系统性能,K均值(K-means)均衡方法可以抑制光无线信道的影响,但其复杂度较高,且在聚类边界处易出现误判。提出了改进聚类中心点的K-means(Improved Center K-means,IC-Kmeans)算法,通过随机生成足够长的训练序列,然后将训练序列每一簇的均值作为K-means聚类中心,避免了传统K-means反复迭代寻找聚类中心。进一步,提出了基于神经网络的IC-Kmeans(Neural Network Based IC-Kmeans,NNIC-Kmeans)算法,使用反向传播神经网络将接收端二维数据映射至三维空间,以增加不同簇之间混合数据的距离,提高了分类准确性。蒙特卡罗误码率仿真表明,IC-Kmeans均衡和传统K-means算法的误码率性能相当,但可以显著降低复杂度,特别是在信噪比较小时。同时,在室内多径信道模型下,与IC-Kmeans和传统Kmeans均衡相比,NNIC-Kmeans均衡的光正交频分复用系统误码率性能最好。
文摘目的基于“紧急输血由急诊科授权医生启动,输血科15 min内发放不超过4 U O型未交叉配血悬浮红细胞”的单中心临床实践,了解该实践背景下紧急输O型未交叉配血悬浮红细胞策略的实施现状,为血液管理提供参考。方法回顾性分析2019年8月—2024年4月四川大学华西医院紧急输O型血患者病例信息,包括申请紧急输血原因、输血申请送达输血科所需时间、输血科血液发放所需时间、患者输血前后总胆红素、间接胆红素、乳酸脱氢酶、患者血型、病情转归等。结果2019年8月—2024年4月本院申请紧急输O型血的患者有39例,共输注未经交叉配血的O型悬浮红细胞90 U。患者均为Rh(D)阳性,其中A型14例;B型6例;O型16例;AB型2例;暂无法定型1例,抗体筛查阳性2例,紧急输O型血的患者中车祸伤是主要原因,占46%(18/39),死亡率51.28%(20/39),死亡原因均为原发伤,无溶血性输血反应的临床指征:输血前后总胆红素(TBTL)、间接胆红素(IBIL)、乳酸脱氢酶(LDH)无统计学差异,P值均>0.05。患者从入院到输血科接收输血申请单和输血科从收到申请单到血液发放的中位时间分别为30.20 min和5.30 min。结论基于“紧急输血由急诊科授权医生启动,输血科15 min内发放不超过4 U O型未交叉配血悬浮红细胞”的单中心临床实践具有安全性,但申请紧急输O型血流程中在输血申请单送达输血科之前有优化空间。
基金Project supported by the National Basic Research Program of China(Grant No.2011CB301701)the National High Technology Research and Development Program of China(Grant Nos.2013AA014402+2 种基金2012AA012202and 2015AA016904)the National Natural Science Foundation of China(Grant Nos.61275065 and 61107048)
文摘The first path-independent insertion-loss（PILOSS） strictly non-blocking 4×4 silicon electro–optic switch matrix is reported. The footprint of this switch matrix is only 4.6 mm×1.0 mm. Using single-arm modulation, the crosstalk measured in this test is-13 dB --27 dB. And a maximum crosstalk deterioration of 6d B caused by two-path interference is also found.
基金The National High Technology Research and Development Program of China(No.2007AA01Z309)the National Natural Science Foundation of China(No.60803160,No.60873030)
文摘In data streams or web scenarios at highly variable and unpredictable rates, a good join algorithm should be able to ＂hide＂ the delays by continuing to output join results. The non-blocking algorithms allow some tuples to be flushed onto disk, with the goal of producing results continuously when data transmission is suspended. But state-of-the-art algorithms have trouble with the constraint of allocated memory. To make better use of memory, a novel non-blocking join algorithm based on hash-merge for improving query response times is proposed. The reduced data structure of in-memory tuples helps to improve memory utility. A replacement selection tree is applied to adjust memory by expanding or shrinking the size of the tree and separates one external join transaction into multi-subtasks. In addition, a cost model to estimate task output rate is proposed to select the in-disk portion that promises to produce the fastest results in the external join stage. Experiments show that the technique, with far less memory, delivers results faster than the three non-blocking join algorithms （ XJoin, HMJ and RPJ ） , with up to almost two-fold improvement in reliable network and one order of magnitude improvement in unreliable network in terms of the number of the reported tuples.
