SRVCC增强技术分析

SRVCC技术用于EPS网络部署的初期阶段,在LTE接入热点覆盖的情况下,利用现有电路域网络实现语音业务的全覆盖。本文介绍了SRVCC的技术特点,分析了SRVCC技术的增强方案,对SRVCC技术的最新进展进行了描述。     

UMTS及EPC网络QoS机制的研究

随着社会的发展,用户对业务质量的需求也日益提高,为此3GPP组织加强了对QoS的研究,在UMTS阶段引入了端到端QoS机制,并在LTE阶段对QoS机制进行了扩展和增强,目前QoS的研究是3GPP研究的一个热点。本文对3GPP移动通信网QoS演进进行了介绍,分析了UMTS和EPC网络的QoS实现机制,并对两种QoS实现机制进行了分析。     

Behavior of EPS geofoam in stress-controlled cyclic uniaxial tests

During recent years, increasing consideration has been given to the compressible inclusion function of EPS geofoam, which makes this cellular geosynthetic an ideal material for reducing the static and seismic lateral earth pressures against rigid non-yielding retaining structures. Although the behavior of EPS geofoam under monotonic loading conditions has been extensively studied using laboratory triaxial compression tests, little research has been done until present on the cyclic stress–strain behavior of this material that is essential for optimizing and improving the seismic buffer function of EPS geofoam in geotechnical earthquake engineering applications. In this context, the present paper summarizes the results of a laboratory study based on stress-controlled cyclic uniaxial tests on EPS samples with various initial (static) deviator stresses. The experimental results indicate a somewhat different dynamic response of geofoam compared to the currently published relationships obtained from strain-controlled cyclic tests. Data from stress-controlled cyclic uniaxial tests show a logarithmic decrease in the damping ratio of EPS geofoam with increasing axial strain amplitude. Furthermore, for cyclic axial strain amplitudes greater than about 0.87–1.0%, the material exhibited a visco-elasto-plastic behavior associated with the occurrence of permanent plastic strains at the end of the cyclic tests.     

EPS板外保温系统施工技术

EPS板外保温系统是由聚合物胶浆、聚苯乙烯板、耐碱玻璃丝网板布组成的一种建筑物外保温系统,目前已是一种成熟的外保温技术。EPS板外保温系统在欧美发达国家已应用近30年,我国应用了10多年,最高建筑能达到44层。     

化学絮凝预处理对膜生物反应器膜污染的影响

以生活污水为原水,对复合式膜生物反应器(HMBR)与传统膜生物反应器(CMBR)进行了对比研究,探讨化学絮凝预处理对膜污染和除污效果的影响。结果表明,相对于CMBR系统,HMBR系统的膜污染速率很低,在近50d的运行中,HMBR的跨膜压差几乎维持在同一水平,而在同等条件下运行的CMBR则从4.59kPa上升到26.18kPa。EPS分析结果表明,HMBR系统中SMP和LB各组分的浓度相对于CMBR系统大大减小,膜污染的速率得到了大幅降低。化学絮凝预处理可有效减缓后续MBR的膜污染,可以作为膜生物反应器的有效预处理方法。此外,HM-BR的出水水质也优于CMBR系统的。     

密肋复合墙体EPS混凝土材料研究

密肋复合墙体是适应我国墙体改革及住宅产业化要求的产物,开发与密肋复合墙结构匹配的填充材料是解决密肋结构优化设计的前提。本文通过4组不同配比EPS混凝土材料试验,研究砂率对EPS混凝土物理及力学性质影响,并通过实测的应力-应变曲线,推导了EPS混凝土材料的应力-应变曲线方程。     

LTE网络中ESM协议分析与设计

论述了纯分组接入的3GPP LTE优化系统,此优化系统可以提供更高的数据速率、更低的传输时延,提高其覆盖范围和频谱利用率.介绍了3GPP提出的有关符合LTE标准一些主要特征,包括优化信令、优化无线传输和无线接入网.主要讨论了符合LTE标准的ESM协议所应考虑的一些内容,如网络控制的业务、QoS聚合和缺省IP接入业务.最后,分析了ESM信令协议的会话建立时延,结果表明,LTE系统中ESM信令协议较先前的3G UMTS系统有很大的改善.     

EPS网络的语音业务解决方案

本文介绍了行业内比较成熟的几种EPS网络语音解决方案,分析了解决方案的特点和具体的实现机制,并结合中国CDMA网络运营商的实际网络情况,给出了相应的建议。     

大掺量工业废弃物EPS保温砂浆组分及其机理

对大掺量工业废弃物EPS颗粒保温砂浆的各组分选择以及几种化学添加剂的性能和作用做了详细的阐述,同时对各种成分作用机理进行了分析,为下一步合理配合比的设计提供了依据。     

Influence of loosely bound extracellular polymeric substances (EPS) on the flocculation, sedimentation and dewaterability of activated sludge

Laboratory experiments on the activated sludge (AS) process were carried out to investigate the influence of microbial extracellular polymeric substances (EPS), including loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS), on biomass flocculation, sludge settlement and dewaterability. The heat EPS extraction method was modified to include a mild step and a harsh step for extracting the LB-EPS and TB-EPS, respectively, from the sludge suspension. Six lab-scale AS reactors were used to grow AS with different carbon sources of glucose and sodium acetate, and different sludge retention times (SRTs) of 5, 10 and 20 days. The variation in the bioreactor condition produced sludge with different abundances of EPS and different flocculation and separation characteristics. The sludge that was fed on glucose had more EPS than the sludge that was fed on acetate. For any of the feeding substrates, the sludge had a nearly consistent TB-EPS value regardless of the SRT, and an LB-EPS content that decreased with the SRT. The acetate-fed sludge performed better than the glucose-fed sludge in terms of bioflocculation, sludge sedimentation and compression, and sludge dewaterability. The sludge flocculation and separation improved considerably as the SRT lengthened. The results demonstrate that the LB-EPS had a negative effect on bioflocculation and sludge-water separation. The parameters for the performance of sludge-water separation were much more closely correlated with the amount of LB-EPS than with the amount of TB-EPS. It is argued that although EPS is essential to sludge floc formation, excessive EPS in the form of LB-EPS could weaken cell attachment and the floc structure, resulting in poor bioflocculation, greater cell erosion and retarded sludge-water separation.