随着运营线路的增多,郑州地铁已进入网络化运营的新阶段,对设备的日常维护也提出了更高的要求,通信专业设备众多,更需要通过智能运维来满足网络化运营的新要求。本文基于车站、控制中心的通信设备的维护现状,通过研究通信专业智能化集...随着运营线路的增多,郑州地铁已进入网络化运营的新阶段,对设备的日常维护也提出了更高的要求,通信专业设备众多,更需要通过智能运维来满足网络化运营的新要求。本文基于车站、控制中心的通信设备的维护现状,通过研究通信专业智能化集中运维方式,优化日常运维场景、故障处理场景、抢险抢修场景下人员分工和生产方式,提出新的基于KVM OVER IP的设备管理架构和运维模式,在不影响现网正常稳定运行、投资成本不高的情况下,实现地铁通信专业设备的集中化、智能化维护,进一步提升设备管理维护水平,同时为下一步建设网管网奠定基石,最终可轻松实现业务、管理2张网运行,结合大数据技术亦可实现地铁通信设备的智能监测、智能分析、智能维护,最大化的增加经济效益。展开更多
Objective: To study contraception among women aged 35 and over at the University Hospital of Brazzaville. Population and Methods: This was a retrospective descriptive study, conducted from April 1st 2017 to January 31...Objective: To study contraception among women aged 35 and over at the University Hospital of Brazzaville. Population and Methods: This was a retrospective descriptive study, conducted from April 1st 2017 to January 31st 2022 in the Obstetrics and Gynecology Department of the University Hospital of Brazzaville, including women aged 35 years and over who had received a contraceptive method. The study variables were sociodemographic, reproductive, clinical and contraceptive method related. Results: Two hundred and thirty customers were collected during the study period, i.e., 10.8% of the patients who received contraception. They were 38.4 ± 3 years old on average, had secondary education (46.1%), were of low socioeconomic status (54.3%), lived with a partner (98.7%) and came from an urban area (97.4%). They were multigravida (85.2%), and multiparous (63.9%) with an average of 4 living children. The indications were of two types: convenience (26.2%) and medical (73.8%). The most commonly used contraceptives were implants (72.2%) and injectable progestin (20.5%). Conclusion: The indication for contraception for women over 35 years of age at the University Hospital Center of Brazzaville is more medical, with the use of long-acting contraceptives.展开更多
Count data is almost always over-dispersed where the variance exceeds the mean. Several count data models have been proposed by researchers but the problem of over-dispersion still remains unresolved, more so in the c...Count data is almost always over-dispersed where the variance exceeds the mean. Several count data models have been proposed by researchers but the problem of over-dispersion still remains unresolved, more so in the context of change point analysis. This study develops a likelihood-based algorithm that detects and estimates multiple change points in a set of count data assumed to follow the Negative Binomial distribution. Discrete change point procedures discussed in literature work well for equi-dispersed data. The new algorithm produces reliable estimates of change points in cases of both equi-dispersed and over-dispersed count data;hence its advantage over other count data change point techniques. The Negative Binomial Multiple Change Point Algorithm was tested using simulated data for different sample sizes and varying positions of change. Changes in the distribution parameters were detected and estimated by conducting a likelihood ratio test on several partitions of data obtained through step-wise recursive binary segmentation. Critical values for the likelihood ratio test were developed and used to check for significance of the maximum likelihood estimates of the change points. The change point algorithm was found to work best for large datasets, though it also works well for small and medium-sized datasets with little to no error in the location of change points. The algorithm correctly detects changes when present and fails to detect changes when change is absent in actual sense. Power analysis of the likelihood ratio test for change was performed through Monte-Carlo simulation in the single change point setting. Sensitivity analysis of the test power showed that likelihood ratio test is the most powerful when the simulated change points are located mid-way through the sample data as opposed to when changes were located in the periphery. Further, the test is more powerful when the change was located three-quarter-way through the sample data compared to when the change point is closer (quarter-way) to the first observation.展开更多
Nonlinear distortion is one of key limiting factors in radio over fiber (RoF) transmission systems. To suppress the nonlinear distortion, digital pre-distortion (DPD) has been investigated considerably. However, for m...Nonlinear distortion is one of key limiting factors in radio over fiber (RoF) transmission systems. To suppress the nonlinear distortion, digital pre-distortion (DPD) has been investigated considerably. However, for multi-band signals, DPD becomes very complex, which limits the applications. To reduce the complexity, many simplified DPDs have been proposed. In this work, a new multidimensional DPD is proposed, in which in-band and out-of-band distortion are separated and the out-of-band distortion is evaluated by sum and differences of all input signals instead of all individual input signals, thus complexity is reduced. An up to 6-band 64-QAM orthogonal frequency division multiplexing (OFDM) signal with each bandwidth of 200 MHz in simulations and a 5-band 20 MHz 64-QAM OFDM signal in experiments are used to validate the pro-posed DPD. The validation is illustrated in the means of power spectrum, AM/AM and AM/PM distortion, and error vector magnitude (EVM) of the received signal constellations. The average EVM improvement by simulation for 3-band, 4-band, 5-band and 6-band signals is 19.97 dB, 18.65 dB, 16.64 dB and 15.44 dB, respectively. The average EVM improvement by experiments for 5-band signals is 8.1 dB. Considering the ten times of bandwidth difference, experiments and simulation agree well.展开更多
随着空间通信系统的发展,CCSDS建议逐渐成为了空间通信的标准,特别是IP over CCSDS Space Links红皮书提出以后,IP已经成为空间信息系统的标准上层应用。提出了一种天地通信系统CCSDS加速网关的设计实现方法,介绍了基于加速网关的天地...随着空间通信系统的发展,CCSDS建议逐渐成为了空间通信的标准,特别是IP over CCSDS Space Links红皮书提出以后,IP已经成为空间信息系统的标准上层应用。提出了一种天地通信系统CCSDS加速网关的设计实现方法,介绍了基于加速网关的天地通信网络结构,描述了其关键技术实现,最后对提出的设计实现方法在OPNET中进行了仿真验证。OPNET仿真结果表明,该技术大大提高了TCP应用在空间链路上的传输效率,而且在多连接共享带宽时保持了较好的公平性。展开更多
针对容量有限的透明IP over WDM网络模型,该文提出一种基于路径的整数线性规划(ILP)方法来优化网络的能耗。相对基于连接的整数线性规划方法,该方法可以在光层提供更多的路径选择组合。仿真结果显示,基于路径的整数线性规划方法能够通...针对容量有限的透明IP over WDM网络模型,该文提出一种基于路径的整数线性规划(ILP)方法来优化网络的能耗。相对基于连接的整数线性规划方法,该方法可以在光层提供更多的路径选择组合。仿真结果显示,基于路径的整数线性规划方法能够通过选择更优的光路组合进一步降低网络的能耗。展开更多
构建IPv6 over DVB体系框架,可以在下一代互联网中利用卫星等广播信道实施远程教育。该体系框架包括"支持IPv6的教育资源管理与发布系统"、"IPv6 over DVB传输系统"以及"IPv6 over DVB在远程教育中的应用示范&...构建IPv6 over DVB体系框架,可以在下一代互联网中利用卫星等广播信道实施远程教育。该体系框架包括"支持IPv6的教育资源管理与发布系统"、"IPv6 over DVB传输系统"以及"IPv6 over DVB在远程教育中的应用示范"3个部分。实现了将IPv6互联网中的教育资源通过卫星链路发布到目前尚无网络覆盖的1000所农牧村中小学。给出了设计方案和部署策略。展开更多
当前空间通信的发展趋势是空间通信网与地面通信网融合,建立天地一体化的信息传输系统。针对天地一体化信息传输系统中IP over CCSDS网关中的协议转换技术开展研究,参考了IP over CCSDS Space Links等相关建议,在Linux内核的网络协议栈...当前空间通信的发展趋势是空间通信网与地面通信网融合,建立天地一体化的信息传输系统。针对天地一体化信息传输系统中IP over CCSDS网关中的协议转换技术开展研究,参考了IP over CCSDS Space Links等相关建议,在Linux内核的网络协议栈中实现了IP协议与CCSDS AOS空间数据链路协议的相互转换,并通过试验对在CCSDS-AOS空间数据链路之上进行IP传输进行了测试与验证,表明了利用IP over CCSDS网关构建天地一体化信息传输系统的可行性,并给出了工程应用的实现建议。展开更多
针对机器人遥操作系统中采用传统网络传输协议传输实时数据的局限性,比较分析TCP和UDP协议的传输特点,提出了在UDP协议上传输TCP服务的TCPOVERUDP技术,详细阐述了TCPOVERUDP技术的实现细节,在应用层实现了TCPOVERUDP传输技术,并把TCPOVE...针对机器人遥操作系统中采用传统网络传输协议传输实时数据的局限性,比较分析TCP和UDP协议的传输特点,提出了在UDP协议上传输TCP服务的TCPOVERUDP技术,详细阐述了TCPOVERUDP技术的实现细节,在应用层实现了TCPOVERUDP传输技术,并把TCPOVERUDP技术应用到机器人遥操作系统的视频传输中。实验结果表明TCP OVER UDP技术在降低视频数据传输丢包率和传输时延两个方面都具有良好的性能。展开更多
文摘随着运营线路的增多,郑州地铁已进入网络化运营的新阶段,对设备的日常维护也提出了更高的要求,通信专业设备众多,更需要通过智能运维来满足网络化运营的新要求。本文基于车站、控制中心的通信设备的维护现状,通过研究通信专业智能化集中运维方式,优化日常运维场景、故障处理场景、抢险抢修场景下人员分工和生产方式,提出新的基于KVM OVER IP的设备管理架构和运维模式,在不影响现网正常稳定运行、投资成本不高的情况下,实现地铁通信专业设备的集中化、智能化维护,进一步提升设备管理维护水平,同时为下一步建设网管网奠定基石,最终可轻松实现业务、管理2张网运行,结合大数据技术亦可实现地铁通信设备的智能监测、智能分析、智能维护,最大化的增加经济效益。
文摘Objective: To study contraception among women aged 35 and over at the University Hospital of Brazzaville. Population and Methods: This was a retrospective descriptive study, conducted from April 1st 2017 to January 31st 2022 in the Obstetrics and Gynecology Department of the University Hospital of Brazzaville, including women aged 35 years and over who had received a contraceptive method. The study variables were sociodemographic, reproductive, clinical and contraceptive method related. Results: Two hundred and thirty customers were collected during the study period, i.e., 10.8% of the patients who received contraception. They were 38.4 ± 3 years old on average, had secondary education (46.1%), were of low socioeconomic status (54.3%), lived with a partner (98.7%) and came from an urban area (97.4%). They were multigravida (85.2%), and multiparous (63.9%) with an average of 4 living children. The indications were of two types: convenience (26.2%) and medical (73.8%). The most commonly used contraceptives were implants (72.2%) and injectable progestin (20.5%). Conclusion: The indication for contraception for women over 35 years of age at the University Hospital Center of Brazzaville is more medical, with the use of long-acting contraceptives.
文摘Count data is almost always over-dispersed where the variance exceeds the mean. Several count data models have been proposed by researchers but the problem of over-dispersion still remains unresolved, more so in the context of change point analysis. This study develops a likelihood-based algorithm that detects and estimates multiple change points in a set of count data assumed to follow the Negative Binomial distribution. Discrete change point procedures discussed in literature work well for equi-dispersed data. The new algorithm produces reliable estimates of change points in cases of both equi-dispersed and over-dispersed count data;hence its advantage over other count data change point techniques. The Negative Binomial Multiple Change Point Algorithm was tested using simulated data for different sample sizes and varying positions of change. Changes in the distribution parameters were detected and estimated by conducting a likelihood ratio test on several partitions of data obtained through step-wise recursive binary segmentation. Critical values for the likelihood ratio test were developed and used to check for significance of the maximum likelihood estimates of the change points. The change point algorithm was found to work best for large datasets, though it also works well for small and medium-sized datasets with little to no error in the location of change points. The algorithm correctly detects changes when present and fails to detect changes when change is absent in actual sense. Power analysis of the likelihood ratio test for change was performed through Monte-Carlo simulation in the single change point setting. Sensitivity analysis of the test power showed that likelihood ratio test is the most powerful when the simulated change points are located mid-way through the sample data as opposed to when changes were located in the periphery. Further, the test is more powerful when the change was located three-quarter-way through the sample data compared to when the change point is closer (quarter-way) to the first observation.
文摘Nonlinear distortion is one of key limiting factors in radio over fiber (RoF) transmission systems. To suppress the nonlinear distortion, digital pre-distortion (DPD) has been investigated considerably. However, for multi-band signals, DPD becomes very complex, which limits the applications. To reduce the complexity, many simplified DPDs have been proposed. In this work, a new multidimensional DPD is proposed, in which in-band and out-of-band distortion are separated and the out-of-band distortion is evaluated by sum and differences of all input signals instead of all individual input signals, thus complexity is reduced. An up to 6-band 64-QAM orthogonal frequency division multiplexing (OFDM) signal with each bandwidth of 200 MHz in simulations and a 5-band 20 MHz 64-QAM OFDM signal in experiments are used to validate the pro-posed DPD. The validation is illustrated in the means of power spectrum, AM/AM and AM/PM distortion, and error vector magnitude (EVM) of the received signal constellations. The average EVM improvement by simulation for 3-band, 4-band, 5-band and 6-band signals is 19.97 dB, 18.65 dB, 16.64 dB and 15.44 dB, respectively. The average EVM improvement by experiments for 5-band signals is 8.1 dB. Considering the ten times of bandwidth difference, experiments and simulation agree well.
文摘随着空间通信系统的发展,CCSDS建议逐渐成为了空间通信的标准,特别是IP over CCSDS Space Links红皮书提出以后,IP已经成为空间信息系统的标准上层应用。提出了一种天地通信系统CCSDS加速网关的设计实现方法,介绍了基于加速网关的天地通信网络结构,描述了其关键技术实现,最后对提出的设计实现方法在OPNET中进行了仿真验证。OPNET仿真结果表明,该技术大大提高了TCP应用在空间链路上的传输效率,而且在多连接共享带宽时保持了较好的公平性。
文摘构建IPv6 over DVB体系框架,可以在下一代互联网中利用卫星等广播信道实施远程教育。该体系框架包括"支持IPv6的教育资源管理与发布系统"、"IPv6 over DVB传输系统"以及"IPv6 over DVB在远程教育中的应用示范"3个部分。实现了将IPv6互联网中的教育资源通过卫星链路发布到目前尚无网络覆盖的1000所农牧村中小学。给出了设计方案和部署策略。
文摘当前空间通信的发展趋势是空间通信网与地面通信网融合,建立天地一体化的信息传输系统。针对天地一体化信息传输系统中IP over CCSDS网关中的协议转换技术开展研究,参考了IP over CCSDS Space Links等相关建议,在Linux内核的网络协议栈中实现了IP协议与CCSDS AOS空间数据链路协议的相互转换,并通过试验对在CCSDS-AOS空间数据链路之上进行IP传输进行了测试与验证,表明了利用IP over CCSDS网关构建天地一体化信息传输系统的可行性,并给出了工程应用的实现建议。
文摘针对机器人遥操作系统中采用传统网络传输协议传输实时数据的局限性,比较分析TCP和UDP协议的传输特点,提出了在UDP协议上传输TCP服务的TCPOVERUDP技术,详细阐述了TCPOVERUDP技术的实现细节,在应用层实现了TCPOVERUDP传输技术,并把TCPOVERUDP技术应用到机器人遥操作系统的视频传输中。实验结果表明TCP OVER UDP技术在降低视频数据传输丢包率和传输时延两个方面都具有良好的性能。
