Overview of Stochastic Vehicle Routing Problems

Stochastic vehicle routing problems (VRPs) play important roles in logistics, though they have not been studied systematically yet. The paper summaries the definition, properties and classification of stochastic VRPs, makes further discussion about two strategies in stochastic VRPs, and at last overviews dynamic and stochastic VRPs.     

机车司机室劳动卫生条件影响的研究——提速铁路运营机车司机室噪声频谱分析

目的为了了解提速及电化改造后机车乘务人员的劳动卫生现状,噪声频谱分析是其中重点项目之一。方法测量与评价方法按GB/T3450-2006《铁道机车和动车组司机室噪声限值及测量方法》随机抽样进行。结果以各型机车司机室噪声LAeq对标合格率评价,存在HXD3、DF8B达标情况较好,而SS7E、DF4达标情况较差的倾向。总体来讲,各型机车组LAeq均值差异有显著意义(F=5.43,P≤0.05);但各型机车司机室噪声LAeq均值除DF4、SS7E型机车超标外,其余四型均符合GB/T3450-2006标准所要求的78 dB(A)的限值;机车噪声是一种频率分布比较宽的混合噪声,其峰值多出现在1 000 Hz周围,在1 000～4 000 Hz人耳声音最为敏感。结论机车司机室噪声均值,除DF4型及SS7E型机车外,其余车型合格率尚可。     

高坡高瓦斯隧道2号横洞工区平导揭煤施工

文章以实际工程为例,首先对平导探煤进行了分析,并对平导瓦斯突出危险性预测进行了讨论,然后阐述了揭煤施工的注意事项,并针对性地提出了有效地安全防护措施,保证了平导顺利穿越煤层,确保了高坡隧道平导顺利安全贯通。     

A Stream Control Transmission Protocol Based OAM System of 3G Cellular Network

OAM （Operations, Administration and Maintenance） system is a very important component of 3G cellular network. In order to acquire overall management, fast response and steady operation, an SCTP （Stream Control Transmission Protocol） based OAM, i. e. , SOAM system was proposed. SOAM implements new characters of SCTP such as multi-stream, enforced SACK and heartbeat mechanism on its transport layer. These characters help SOAM decrease the message transmission delay and accelerate the link failure detection. Besides, a new component named SOAM agent was introduced to improve the operation efficiency of SOAM. The experimental results prove the proposed SOAM system achieves better performance on signaling transmission compared with conventional TCP based OAM system.     

Fuzzy C-Means Clustering Based Phonetic Tied-Mixture HMM in Speech Recognition

A fuzzy clustering analysis based phonetic tied-mixture HMM (FPTM) was presented to decrease parameter size and improve robustness of parameter training. FPTM was synthesized from state-tied HMMs by a modified fuzzy C-means clustering algorithm. Each Gaussian codebook of FPTM was built from Gaussian components within the same root node in phonetic decision tree. The experimental results on large vocabulary Mandarin speech recognition show that compared with conventional phonetic tied-mixture HMM and state-tied HMM with approximately the same number of Gaussian mixtures, FPTM achieves word error rate reductions by 4.84% and 13.02% respectively. Combining the two schemes of mixing weights pruning and Gaussian centers fuzzy merging, a significantly parameter size reduction was achieved with little impact on recognition accuracy.     

Improving Mobility Management for All-IP Radio Heterogeneous Network Using SCTP

IntroductionFuture mobile communication network willconsist of multiple traffics and access technologies.It is to certainty a radio heterogeneous network(RHN) because none of the current networks canprovide ubiquitous coverage and all-around ser-vices[1]. Future mobile terminal will be multi-modethat maintains connectivity to different radio accesspoints, so RHN should be scalable and support theevolution and upgrade of individual network ele-ments. All-IP architecture is an inevitable way…     

复合胺溶液脱除CO2性能研究

开发了一种新型的复合胺吸收剂,考察了该复合胺吸收剂和一乙醇胺溶液对二氧化碳的吸收和解吸能力,并在原理试验流程上评价了2种溶液对低浓度二氧化碳的连续吸收性能.结果表明,该复合胺吸收剂对二氧化碳具有较高的吸收速率和吸收容量,容易再生;在相同工艺条件下,复合胺溶液对低浓度二氧化碳的连续清除效率与一乙醇胺溶液相近,但稳定性更好.     

雷达辐射源信号识别方法性能比较分析

从正确识别率、识别速度等方面比较了粗糙集理论、灰关联理论、径向基神经网络、支持向量机等几种雷达辐射源信号识别方法的性能,并通过大量仿真得出了这些识别方法的性能优劣的结论及影响雷达辐射源信号识别正确率和识别时间的因素。