无机氧化物填料对硅橡胶泡沫材料力学和阻燃性能的影响

以氧化铜、二氧化钛和高岭土作为无机增强填料,分别与羟基、乙烯基和含氢硅油进行复合,在室温和铂催化下,通过硅氢加成和硅氢缩合脱氢反应制备了一系列硅橡胶泡沫复合材料,探讨了不同无机填料对硅橡胶泡沫材料微观形貌、力学和阻燃性能的影响,以及泡孔结构与力学和阻燃性能的关系。结果表明,高岭土能够更好地分散于硅橡胶泡沫材料中,还能明显增强材料的力学和阻燃性能,热释放量和产烟量显著下降。与空白硅橡胶泡沫材料相比,含高岭土硅橡胶泡沫材料的拉伸强度、扯断伸长率、压缩强度、极限氧指数及UL-94等级分别提升至106.1 kPa、42.3%、35.2 kPa、32.7%和V-0级,总热释放量和总产烟量分别下降了51.1%和84.2%。

一种基于增强型奇偶校验码改进的极化码EPC-MS-SCL译码算法

针对基于路径分裂策略辅助极化码串行抵消列表(Path Splitting Selecting strategy based on Search Set under the Successive Cancellation List,PSS-SS-SCL)译码算法性能的不足,提出了一种利用增强型奇偶校验码改进PSSSS-SCL译码算法的EPC-MS-SCL(Enhanced Parity Check and Monte Carlo Segment aided Successive Cancellation List)译码算法.该算法在极化码编码阶段对信息序列做分段处理,在每段末尾添加增强型奇偶校验码,译码器仅在译码搜索集内元素时进行路径分裂,其余元素直接执行硬判决译码,并在译码完一段序列后立即对该段进行校验,仅保留通过校验的路径,从而减少了错误路径对正确路径的竞争,使正确路径保留到译码结束的概率增加,改善了译码性能,同时减少了译码列表数,使得译码复杂度更低.仿真结果表明,与PSS-SS-SCL译码算法相比较,所提出算法能在一定程度上改善其性能增益且具有更低的译码复杂度.

超声波辅助提取黑果腺肋花楸花色苷工艺优化及稳定性研究

以黑果腺肋花楸为原料,在单因素实验的基础上应用响应面法对其提取条件进行优化,并研究稳定性。优化黑果腺肋花楸花色苷提取条件为乙醇浓度为63%、超声时间为32 min、超声温度为42℃、料液比为1∶20(g/m L),在此条件下的黑果腺肋花楸花色苷的提取量为5.61 mg/g。在50℃以下的条件下黑果腺肋花楸花色苷稳定性较好,保存率可达98%以上;氧化剂对黑果腺肋花楸花色苷有显著破坏作用;在避光的条件下黑果腺肋花楸花色苷稳定性最好;Ca^(2+)、K^+、Mg^(2+)离子对黑果腺肋花楸花色苷几乎无破坏作用,但Fe^(2+)、Cu^(2+)离子的破坏作用较为显著;在偏酸性条件下黑果腺肋花楸花色苷稳定性较好。

固定源三氧化硫测试技术研究

通过分析国内外SO3相关测试标准和技术,探讨了SO3采样及硫酸根滴定方法,以及烟气协同治理技术路线中SO3测试方法,旨在探索一种科学合理的SO3工程测试技术和方法。

Study on New Concatenated Code in WDM Optical Transmission Systems

A new concatenated code of RS(255,239)+BCH(2 040,1 930) code to be suitable for WDM optical transmission systems is proposed. The simulation results show that this new concatenated code, compared with the RS(255,239)+CSOC(k0/n0=6/7, J=8) code in ITU-T G.75.1, has a lower redundancy and better error-correction performance, furthermore, its net coding gain(NCG) is respectively 0.46 dB, 0.43 dB more than that of RS(255,239)+CSOC(k0/n0 =6/7, J=8) code and BCH(3 860,3 824)+BCH(2 040,1 930) code in ITU-T G.75.1 at the third iteration for the bit error rate(BER) of 10-12. Therefore, the new super forward error correction(Super-FEC) concatenated code can be better used in ultra long-haul, ultra large-capacity and ultra high-speed WDM optical communication systems.

基于人工蜂群算法的多用户OFDM自适应资源分配方案

针对多用户正交频分复用(OFDM)自适应资源分配中用户公平性和系统容量的问题,本文提出了一种联合子载波分配和功率分配的方案。在子载波分配中,首先确定每个用户需要的子载波数量,然后根据用户的速率比例继续分配子载波,最后分配剩余子载波。在功率分配中,通过人工蜂群(ABC)算法的全局搜索实现在所有用户之间的功率寻优,并利用等功率的分配方式对每个用户的子载波进行单用户功率分配。从仿真结果中可以看出,本文算法不仅可以兼顾用户的公平性,同时也有效地提高了系统的吞吐量,从而证明了本文算法的有效性。

北京市通州区319例尘肺病患者健康寿命损失年的计算及分析

目的了解北京市通州区319例尘肺病患者的健康寿命损失年(years lived with disability,YLD)情况,为该地区今后的尘肺病防治工作提供一定的数据支持。方法以截止到2021年7月31日通过“职业病及健康危害因素监测信息系统”平台获得的北京市通州区319例尘肺病个案资料作为分析对象,描述尘肺病患者的一般情况、YLD情况,分析YLD在不同分层情况下的数据对比情况。结果319例尘肺病患者的年龄分布在30~86岁,平均(52.41±11.75)岁。319例尘肺病患者的YLD合计为2704.66年,M(P_(25),P_(75))为8.41(2.03,15.62)年。<40岁年龄段患者的YLD高于其他年龄段患者(H=124.553,χ^(2)=23.112、18.212、17.257、40.357,均P<0.05),尘肺Ⅰ期患者的YLD高于其他分期的患者(H=88.634,χ^(2)=25.331、38.112,均P<0.05),石棉肺患者的YLD高于其他尘肺类型患者(H=136.520,χ^(2)=24.368、37.258、24.125,均P<0.05),伤残等级数值较高患者的YLD高于其他伤残等级数值较低的患者(H=87.632,χ^(2)=32.358、31.256、29.994,均P<0.05),私有经济企业患者的YLD高于其他经济类型的患者(H=99.657,χ^(2)=39.945、42.309,均P<0.05),微型以及小型企业患者的YLD高于其他企业规模的患者(H=162.58,χ^(2)=77.425、61.258、80.354、48.369、62.007、72.358,均P<0.05),不同居住街道尘肺病患者的YLD数据比较,差异无统计学意义(H=1.023,P>0.05)。结论尘肺病会给患者个体带来较为沉重的健康寿命损失,尤其对于<50岁的职业人群的健康监测需要重度关注。另外,需要有关部门对微小型私有企业进行严格的监管,降低尘肺病的发病率,推迟发病时间,有效减轻尘肺病的健康负担。

A new construction method of QC-LDPC codes with low error floor based on EETS and Zig-Zag

Aiming at the problem that quasi-cyclic low density parity check(QC-LDPC) codes may have the error floor in the high signal to noise ratio(SNR) region, a new construction method of the QC-LDPC codes with the low error floor is proposed. The basic matrix of the method is based on the progressive edge growth(PEG) algorithm and the improved eliminate elementary trapping sets(EETS) algorithm so as to eliminate the elementary trapping sets in the basic matrix,then the Zig-Zag method is used to construct the cyclic shift matrix which is used to extend the basic matrix in order to construct the parity check matrix. The method not only can improve the error floor in the high SNR region, but also can flexibly design the code length and code rate. The simulation results show that at the bit error rate of 10-6, the PEG-trapping-Zig-Zag(PTZZ)-QC-LDPC(3024,1512) codes with the code rate of 0.5, compared with the PEG-Zig-Zag(PZZ)-QC-LDPC(3024,1512) codes and the PEG-QC-LDPC(3024,1512) codes, can respectively improve the net coding gain of 0.1 dB and 0.16 dB. The difference among the bit error rate performance curves will become better with the increase of the SNR. In addition, the PTZZ-QC-LDPC(3024,1512) codes have no error floor above the SNR of 2.2 dB.

A novel phase noise compensation algorithm combining the DF algorithm with LCSC algorithm in CO-OFDM systems

A novel phase noise(PN)compensation algorithm based on the decision feedback(DF)algorithm and the linear combination self cancellation(LCSC)algorithm is proposed to improve the system performance degradation caused by laser linewidth in coherent optical orthogonal frequency division multiplexing(CO-OFDM)systems.In this proposed LCSC-DF algorithm,the LCSC algorithm is used to precode the subcarrier information at the transmitter and decode the demodulation information and inter-carrier interference(ICI)related information at the receiver.And then the pilot information is used to obtain the final compensation signal by the improved DF algorithm.The simulation results show that the PN compensation performance of the proposed LCSC-DF algorithm is better than that of the DF algorithm.Furthermore,with the increase of the signal to noise ratio(SNR),its bit error rate(BER)performance approaches to that of the SC-DF algorithm at the larger PN linewidth.The subcarriers utilization ratio of the proposed algorithm is higher than that of the SC-DF algorithm.As a result,the proposed algorithm can effectively improve the performance of the system.