Average Level Crossing Rate and Fading Duration of Multiuser Single Relay Cooperation Wireless Uplinks

We investigate the average Level Crossing Rate （LCR） and Average Fading Duration （AFD） of multiuser single relay co- operation wireless uplinks over independent and non-identically distributed （i.ni.d） Ray- leigh fading channels. We first present the statistical analyses of the first-hop equivalent envelope. Then, we investigate the LCR and AFD of an equivalent end-to-end envelope, and present the closed-form solutions to LCR and AFD, which are given with integral forms. Finally, we derive the Laplace approximations of LCR and AFD as well as the upper and lower bounds. The numerical results of LCR show that the upper bound is tight. For multi user systems with different number of mobile users, the analyses indicate that the LCRs are approximately the same at the low level of the envelope. envelope However, there are at the high level of the reasonable differences among the curves of LCRs. Due to that fact that AFD is the inverse function of LCR, the results for AFD are the opposite.

Alcohol drinking rates of male between 7th and 11th graders in Japan decreased gradually based on nationwide repeated cross-sectional surveys from 1996 to 2008

Early drinking is considered to result in making tolerant of alcohol consumption and a higher prevalence of alcohol related disorders in the later. We focused generational impacts on drinking rate among high school students based on multiple nationwide data. The surveys were nationwide, cross-sectional random sampling surveys given every 4 years from the Japanese Youth Tobacco and Alcohol Surveys, 1996 to 2008. Participants were male 53,925 high school students from 7th grade to 11th grade. We divided to the three follow-up groups every 4 years from 1996 to 2004 for male junior high school students in 7th grades and the end periods were 4 years later in 11th grades. Outcome measures in this study were life time drinking, current drinking within 30 days and weekly drinking. All drinking rates decreased each at 7th and at 11th grade. The increments in these drinking rates from 7th grade to 11th grade in males decreased gradually in recent follow-up groups. Generational impacts should be considered by using follow-up groups to study drinking behaviors among students.

Calculation of Photo-Ionisation Cross Sections and Radiative Recombination Rate Coefficients for CO and CO^+ Molecules

A method based upon the weighted total cross section （WTCS） theory is proposed to calculate the photo-ionisation cross sections and the radiative recombination rate coefficients between the fundamental level of CO and the main electronic states of its corresponding ion. Total photo-ionisation cross sections and radiative recombination rate coefficients are determined from the calculation of elementary vibrational photo-ionisation cross sections. Transitions be- tween CO＋（X, A and B） and CO（X） are considered. Total photo-ionisation cross sections and recombination coefficients are computed in the temperature interval 500-15000 K.

Smoking rate trends of male 7th and 11th graders in Japan based on repeated, nationwide, cross-sectional surveys every 4 years from 1996 to 2008

Backgrounds: Smoking in childhood has become an important public health concern. Previous studies have reported on secular trends in childhood smoking rates and compared with smoking rates at fixed ages. They also described secular trends regarding the prevalence of smoking at fixed ages. The variations in smoking rate of young children and adolescents by follow-up groups have not been studied by follow-up groups at a national level. Objective: We looked at trends and generational impacts on smoking rate by using follow-up groups of male Japanese high school students to quantitatively assess differences in trends, based on multiple nationwide data from the Japanese Youth Tobacco and Drinking Surveys gathered every 4 years between 1996 and 2008. Methods: The surveys were nationwide, cross-sectional random sampling surveys given every 4 years from 1996 to 2008, using the single-stage cluster sampling methodology. The cluster unit of the sampling was school. The survey targeted junior and senior high school students from schools selected through Japan using the National School Directory. Students enrolled in the sampled schools were subjects of the study. Participants were 53,925 high school students from 7th grade to 11th grade in 1996, 2000, 2004 and 2008. We divided the three follow-up groups every 4 years from 1996 to 2004 for male junior high school students in 7th grades, age 13. The end periods were 4 years later when they had become 11th graders, age 17, from 2000 to 2008. Main outcome measures in this study were life time smoking, current smoking within 30 days and daily smoking at 7th or 11th grade and the trend of the smoking rates between 7th to 11th grades. Results: Life time smoking rate, current smoking rate and daily smoking rate in Japanese high school students decreased at 7th grade from 1996 to 2004. They also decreased at 11th grade from 2000 to 2008. However, the slopes differed among their follow-up groups. The increments in their smoking rates from 7th grade to 11th grade in male high school students were smaller in recent follow-up groups both in 2000 and in 2004 than in follow-up groups in 1996. Then, those increments in follow-up groups between in 2000 and in 2004 were similar in lifetime smoking rate and current smoking rate. Conclusions: We have shown that monitoring trends by follow-up group are important in studying smoking for public health. Values of smoking rates from a young age to adolescence by follow-up group should be examined. Values of smoking rate and regular changes in smoking rate are important because smoking rate changes dynamically during adolescence. Not only trends in smoking rates at fixed ages, but also generational impacts should be considered by using follow-up groups to study smoking behaviors among students. We need to continue careful monitoring of follow-up group smoking prevalence. When long-term health promotions are planned or assessed, policy makers need to look at changes in follow-up groups.

基于一个新SiH_(2)(1^(1)A′)势能面的H+SiH反应动力学研究

本文基于2022年报道的一个SiH_(2)(1^(1)A′)势能面,运用切比雪夫波包方法对H(^(2)S)+SiH(X^(2)П;v=0;j=0)→Si(^(1)D)+H_(2)(X^(1)∑_(g)^(+))反应体系在1:0×10^(-3)-1.0 eV的碰撞能量范围内进行动力学研究.分别应用忽略科里奥利耦合效应的耦合态近似和精确量子力学计算得到该反应的反应概率、积分散射截面和速率常数.计算发现在J较大时,科里奥利耦合效应显著提升该反应的反应概率,忽略科里奥利耦合效应会使H+SiH反应的积分散射截面和速率常数减小,对于速率常数而言,温度越高,两种计算方法所得结果的差距越大.精确的量子力学计算结果表明,H+SiH反应的速率常数在300-1000 K之间几乎不随温度改变,这与H+CH反应非常相似,但是在数值上,前者比后者大1个数量级.

内蒙古自治区社区5类精神障碍患者精神卫生服务利用现状

目的:描述内蒙古自治区社区5类精神障碍终生患者精神卫生服务利用现况,为健康教育和制定相关政策提供参考。方法:采用分层多阶段不等概率抽样方法抽取内蒙古自治区18岁及以上常住居民共12 315名,采用复合性国际诊断交谈表调查心境障碍、焦虑障碍、物质使用障碍、间歇爆发性障碍、进食障碍等5类精神障碍及精神卫生服务利用现况,以单因素分析方法进行描述性统计。结果:5类精神障碍中,任何一种精神障碍终生患者咨询率为18.7%,治疗率为10.2%,患者接受非医务工作者治疗的比例最高(31.4%),其次是接受精神科或心理科医生治疗;患者中有1.1%的患者接受药物治疗,有2.5%的患者接受心理治疗。结论:内蒙古自治区精神障碍患者精神卫生服务利用率较低,要广泛开展正确求医的健康教育。

A NOVEL CROSS-LAYER STRATEGY OF VIDEO TRANSMISSION TO SOLVE PERFORMANCE ANOMALY IN MULTI-RATE IEEE 802.11 NETWORKS

When wireless hosts use different rates to transmit data in IEEE 802.11 networks, it will take on the state of performance anomaly which will severely decrease the throughputs of all the higher rate hosts. Hence, it is bad for video service transmission. Considering that video is very sensitive to packet delivery delay but can tolerate some packet losses, we propose a novel cross-layer scheme which takes these two characteristics into consideration. Firstly, the maximum number of retransmissions for a video Medium Access Control (MAC) frame is computed in MAC layer according to video frame rate requirement of application layer and current access delay of MAC layer. Secondly, within the margin of the tolerant Packet Loss Rate (PLR) of application layer, several video MAC frames are allowed to drop so that we can adaptively select the transmission rate as high as possible for the rest of video MAC frames in terms of current channel quality and the maximum number of retransmissions. Experiment results show that the proposed method can reduce the delay and jitter of video service and improve the throughputs of fast hosts. Therefore, it increases the quality of reconstructed video to a certain extent and relieves the performance anomaly of network effectively.

产能分享平台企业的盈利模式选择与定价研究

在分享经济背景下,考虑交叉网络外部性效用及平台匹配率,研究产能分享平台的盈利模式选择与定价问题。基于两阶段博弈方法,分析并比较了平台在利润最大化和社会福利最大化条件下选择服务费模式与注册费模式时获得的最大利润。研究发现,在目标时间段内,当平台以利润最大化为目标时,多数情况下选择注册费模式获得的最大利润高于选择服务费模式获得的利润。在特定条件下,也存在平台采取两种盈利模式会获得相同利润的情况。此外,平台最大利润在一定条件下与交叉网络外部性系数和平台对制造能力供应方的匹配率正相关,与对制造能力需求方的匹配率负相关。当平台以社会福利最大化为目标时,选择服务费模式获得的利润高于选择注册费模式时的利润。最后,通过数值算例对上述结果进行了验证。

高重复频率猝发多脉冲加载下交联聚苯乙烯真空沿面闪络特性

基于高重复频率强流多脉冲加速器的应用需求,针对交联聚苯乙烯(XLPS)材料在猝发多脉冲下的真空沿面闪络特性开展了实验研究。采用放置于平板电极中的XLPS圆台样品,在脉宽120 ns的单个脉冲和间隔500 ns的三脉冲加载下开展了真空沿面闪络实验,通过对实验平台和实验规范的优化设计,有效提升了实验效率和数据有效性,观测到了样品发生真空沿面闪络前的试样电压顶降现象和前序脉冲闪络对后续脉冲的显著影响,获得了XLPS材料在相应条件下真空沿面闪络的统计数据。在实验基础上,对XLPS材料在高重复频率多脉冲加载下的真空沿面闪络特性进行了分析,为高重复频率多脉冲加速器的绝缘设计提供了实验依据。

On Cross-Layer Design of AMC Based on Rate Compatible Punctured Turbo Codes

This paper extends the work on cross-layer design which combines adaptive modulation and coding at the physical layer and hybrid automatic repeat request protocol at the data link layer. By contrast with previous works on this topic, the present development and the performance analysis as well, is based on rate compatible punctured turbo codes. Rate compatibility provides incremental redundancy in transmission of parity bits for error correction at the data link layer. Turbo coding and iterative decoding gives lower packet error rate values in low signal-to-noise ratio regions of the adaptive modulation and coding (AMC) schemes. Thus, the applied cross-layer design results in AMC schemes can achieve better spectral efficiency than convolutional one while it retains the QoS requirements at the application layer. Numerical results in terms of spectral efficiency for both turbo and convolutional rate compatible punctured codes are presented. For a more comprehensive presentation, the performance of rate compatible LDPC is contrasted with turbo case as well as the performance complexity is discussed for each of the above codes.

挪威红牛改良荷斯坦奶牛的妊娠率分析

[目的]研究现存混养的条件下挪威红牛配种荷斯坦奶牛后的妊娠优势,以提高荷斯坦奶牛的繁殖力。[方法]以荷斯坦奶牛作为母本,进口挪威红牛冻精为父本,进行杂交改良(挪威红牛♂×荷斯坦奶牛♀),培育杂种牛,统计不同月份、不同年龄段的配种数、妊娠数、妊娠率。[结果]杂交种牛相比于荷斯坦牛,自然发情配种的妊娠率提高36.41百分点;同期处理配种,妊娠率提高30.24百分点;青年牛配种,妊娠率提高47.64百分点;群体年度配种,妊娠率提高了36.83百分点,杂交牛场配种妊娠率显著高于荷斯坦牛场。[结论]杂交牛场经过挪威红牛乳肉兼用型牛的品种改良,明显提高了牛场群体繁育率。

甘肃省成年居民婚姻状况与腰椎间盘突出症的关联研究

目的了解甘肃省成年居民婚姻状况与腰椎间盘突出症的关系。方法于2022年5月—2022年7月在甘肃省根据海拔(≥3500 m、1500~3500 m、<1500 m)进行分层整群抽样,共调查4598人。对所有研究对象进行问卷调查、体格检查、血糖血脂检测。采用单因素分析与非条件二元Logistic回归模型分析婚姻状况与腰椎间盘突出症的关联性。结果本次调查最终有效样本为4545例。有配偶者腰椎间盘突出症患病率为24.49%,高于无配偶者,差异有统计学意义(P<0.05);在有配偶者中,腰椎间盘突出症患病率女性高于男性,<45岁年龄段高于其他年龄段,藏族高于其他民族,差异均有统计学意义(P<0.05)。二元Logistic回归分析结果显示,有配偶者中女性、年龄≥45岁、农林牧渔、工人、其他职业、居住海拔≥1500 m,高血压均为腰椎间盘突出症的危险因素(OR>1)。结论甘肃省成年居民有无配偶状态与腰椎间盘突出症患病存在关联,且有配偶者患病率相对较高。

澳洲坚果主导品种Own Choice的品种配置研究

为了明确澳洲坚果园主导品种Own Choice(O.C)的最适配置品种,选择HAES863、D、D4、HAES816、HAES906、HAES294、HAES900、A4等8个品种为O.C授粉,统计分析不同授粉处理的着果率、杂交不亲和性程度指数、着果花序率、每果序着果数、落果率、壳果横径等指标。结果表明,以着果率及着果花序率统计的杂交不亲和性程度指数发现,HAES863、D、D4、HAES816、HAES906与O.C的杂交亲和性高于A4、HAES294、HAES900。供试品种处理的着果率与着果花序率之间存在正相关关系,初步推断可使用着果花序率代替着果率评价O.C与不同品种的杂交不亲和性程度;8个授粉处理的平均着果花序率为40.60%,可以此推断O.C与不同授粉品种的田间杂交不亲和性程度。综合分析推断,澳洲坚果主导品种O.C的最适配置品种为HAES863和D4,根据小气候可选择性搭配种植D、HAES906、HAES816。

上海市黄浦区老年人轻度认知障碍影响因素研究

目的对上海市黄浦区老年人群轻度认知障碍的患病情况、影响因素进行调查,旨在探索黄浦区60岁及以上老年人轻度认知障碍的相关因素,寻找可以改变的影响因素,为轻度认知障碍(MCI)的早期防治等提供科学依据。方法于2023年1月-2023年7月采用多阶段分层整群随机抽样的方法抽取上海市黄浦区60周岁及以上常住人口进行问卷调查,使用MoCA-B量表进行认知功能评价。采用单因素和多因素二分类Logistic回归分析60岁及以上老年人群患MCI的影响因素。结果802例被调查老年居民,MCI患病率31.80%。Logistic回归分析结果显示:高文化程度、经常饮茶、体育锻炼,为老年人群患MCI的独立保护因素;年龄大、脑卒中、高血压、独居是MCI的独立危险因素。结论黄浦区社区老年MCI患病率较高。一方面对高龄、文化程度低的人群和特定的患病人群(高血压、脑卒中),制定个性化干预模式,建议临床医护、家庭和社区密切配合;另一方面为社区内老年人提供早期的认知训练和健康促进活动,积极参加体育锻炼,鼓励老年人参加社交活动。

老年男性人群跌倒发生率及相关危险因素的现况调查

目的系统评估老年男性人群跌倒发生情况,调查与跌倒相关的危险因素。方法在60岁以上老年男性群体中开展调查,评价指标包括受试者一般信息、跌倒史、生活习惯、病史、体检信息、运动能力、肌肉力量、步行能力、平衡能力、认知状态等,研究老年人跌倒发生风险因素及相关损伤情况,根据1年内跌倒史分为跌倒组与非跌倒组,比较两组间各项指标差异,通过单因素与多因素二元logistic回归分析,探索其相关因素。结果完成调查520名,平均(77.21±9.70)岁,近1年内跌倒发生率31.35%;既往跌倒损伤率33.6%,既往跌倒失能发生率31.9%。跌倒高危时间为清晨与深夜,地点是卧室、卫生间,跌倒多在行走中发生,跌倒方式主要为滑倒与绊倒。环境原因主要是地面湿滑、障碍物,个人原因复杂。跌倒组(163名)与非跌倒组(357名)在年龄、日常生活活动能力(ADL)、工具性日常生活活动(IADL)量表、简易精神状态检查表、下肢肌力、单腿平衡(SLBT)、计时“起立-行走”试验、5次坐立试验、步速、功能性步行量表、运动史及多病状态上有差异。单因素Logistic回归分析显示,老年男性人群跌倒发生的危险因素有高龄、IADL功能差、多病状态,以及脑卒中、体位性低血压、消化疾病、肌骨疾病、听觉损失等多种疾病,保护因素有运动史、ADL、认知功能、下肢肌力、SLBT、行走能力等。多因素Logistic回归显示,老年男性人群跌倒的危险因素有高龄(OR=1.085,95%CI:1.026~1.147)、脑卒中(OR=2.528,95%CI:1.118~5.717)、体位性低血压(OR=2.845,95%CI:1.249~6.481),保护因素有良好的ADL(OR=0.944,95%CI:0.931~0.959)、下肢力量(OR=0.842,95%CI:0.784~0.905)、SLBT(OR=0.705,95%CI:0.633~0.786)。结论老年男性人群的跌倒发生率较高,跌倒风险随年龄增加而升高,跌倒后易发生损伤、失能。跌倒与自身原因、时间、环境有关,高龄、日常生活能力水平低、下肢力量与平衡能力下降及有脑卒中、体位性低血压病史的老年男性跌倒风险更高。

人民币汇率升值、贸易开放水平与跨境人民币结算

本文基于2011—2021年我国省级平衡面板数据,使用pvar模型研究跨境人民币结算金额、人民币汇率及贸易开放三者之间的动态关系。结果表明:保持一定规模的贸易开放及稳中有升的人民币币值会助推跨境人民币结算规模的扩大,进而推进人民币国际化进程。基于此,本文就进一步发挥稳定的对外开放水平和稳中有升的人民币币值对跨境人民币结算的促进作用提出相关政策建议,以供参考。

柔性直流输电系统的高频谐波保护方法与工程实践

柔性直流输电系统受电力电子设备本身特性以及控制系统影响,在多种运行工况下易出现不同频率的振荡问题。作为实现设备安全和电网稳定运行的决定因素,保护系统应实现对系统谐波的准确监测以及可靠动作。根据高频振荡时的电流能量累积作用,给出了基于反时限动作的电流类谐波保护算法。基于高频谐波电压特性,分别给出了过零点监测保护算法、谐波畸变率保护算法以及宽谐波保护算法,各保护算法相互配合,实现对不同电压振荡类型的全面保护。最后,给出了国内柔性直流工程实践中配置的高频谐波保护,结合保护原理对系统发生高频振荡后的动作特性进行分析,验证了高频谐波保护的有效性和准确性。

交叉扩散驱动的SI模型空间斑图

目前国内外关于SI模型空间格局的研究大多数局限在自扩散以及系统参数对斑图模式的影响,而关于交叉扩散对空间格局的演化机理研究成果较少.本文建立了一个具有自扩散和交叉扩散的空间流行病模型,研究了在有无自扩散驱动系统不稳定的情况下,交叉扩散对SI模型的稳定性、稳定速度以及斑图结构的影响.研究发现,在无自扩散驱动系统不稳定的情况下,引入交叉扩散能够激发Turing斑图的产生;在自扩散驱动系统不稳定的情况下,交叉扩散可以实现斑图结构的改变;对于SI模型的稳定速度,不论有无自扩散驱动系统不稳定,交叉扩散都影响了其到达稳定所需时间,且在不同的交叉扩散系数下,所需时间也不同.因此,交叉扩散对于SI模型的稳定性、稳定速度、斑图结构都有重要的影响.

声波法在输油管道上的可检测泄漏率分析

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