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21.
万智萍 《重庆邮电大学学报(社会科学版)》2016,(5)
为了提升认知无线网络的数据传输效率,优化节点能量负载,提出一种协同路由算法。基于覆盖与底层技术的协作设计一种协同网络架构,该架构针对网络频带表现多样化提供了一种新的频谱选择策略,提升频谱资源效用。结合协同网络频谱选择时的干扰特性,根据频谱、干扰和功率约束关系,提出最大化链路容量的频谱及节点功率分配方法。在协同路由设计上引入了频谱效用参数,参数的度量标准涉及节点剩余能量和链路容量,以优化路由节点能量负载和传输效率为目的。仿真对比结果表明,算法有效地利用信道接入机会进行数据转发,提高了传输效率,相比基于竞争进化算法的多播路由方法,数据包传递成功率提升了1.4%,平均网络吞吐量高出8.4%,平均节点剩余能量高出3.2%,在均衡节点负载上性能良好。 相似文献
22.
Interpretive phenomenological analysis was used to investigate the experiences of six African immigrant mothers living in the United Kingdom with a child diagnosed with an Autism Spectrum Disorder (ASD). The mothers took part in one-off, semi-structured interviews. Four themes were identified: caring for a child we did not expect, the pain of stigma and rejection, frameworks of meaning, and negotiating conflicting cultural beliefs. Many aspects of the mothers’ experiences appear related to their position as immigrants from cultures with contrasting belief systems regarding child development and disability. Conflicts between African cultural beliefs and a western, medical understanding of ASD appeared to create a feeling of cognitive dissonance for the mothers. The strategies used to negotiate this appear to map onto Berry’s acculturation strategies, suggesting that the experience of having a child with ASD impacts upon the acculturation process. Implications for clinical practice and policy are discussed. 相似文献
23.
给出了带有复值周期系数q(x)=^∞Σk=1ake^ikx(其中^∞Σk=1∣ak∣〈∞)的常型J-自伴Hill算子在反周期边界条件下的Floquet判别式及其谱. 相似文献
24.
本文利用序列的双重性原理对移动傅立叶变换作了深入的研究.根据频率采样理论,将模拟系统的传递函数H(ω)分解为若干子系统之和,并画出其结构框图,这个系统可以用来测量模拟信号的移动离散谱,也可用作低通、带通或梳状滤波器.最后还给出实现该系统的具体方框图. 相似文献
25.
马飞 《榆林高等专科学校学报》2007,17(6):57-59
对DS(直接序列)、FH(跳频)和TH(跳时)三种主要扩频通信体制的抗干扰性能进行综合比较,分析研究了近几年来出现的新型干扰抑制技术,探讨了扩频通信在干扰抑制方面的潜力。 相似文献
26.
通过分析左定与右定问题的关系,应用谱曲线和高阶右定问题的谱,研究了一类高阶左定问题谱的特性及谱对给定参数的可微性. 相似文献
27.
扩频通信在无线局域网中的应用 总被引:4,自引:0,他引:4
吴凡 《浙江树人大学学报》2005,5(4):99-102
阐述目前无线局域网的特点和主要传输方式及扩频通信的主要工作原理,并就直接序列扩频、跳频扩频、跳时扩频和脉冲线形扩频四种扩频技术工作原理、扩频技术的四大特点和扩频技术在无线局域网中的应用前景等作了介绍. 相似文献
28.
In China, family care is the dominant form of care for people with mental disorders. Since 2004, the government has been developing a community‐care model that places more responsibility on community organisations and the local governments at the provincial, municipal and county levels for the provision of formal care. As a large number of people with severe mental disorders live in rural China, this case study was conducted in a rural county in order to examine the development of community care. It was found that, although family care remains dominant, families’ need for formal care is increasing. Community services have improved, but their development is constrained by several contextual and micro factors. In this study, it is argued that the community‐care model introduces a process of reconfiguration of the relative responsibility for care among the family, social organisations and the government, but progress depends on further administrative and fiscal reforms. 相似文献
29.
Parents with substance use disorders (SUD) require treatment and support in order to provide children with appropriate care and protection. Using the 2012 National Child Abuse and Neglect Data System (NCANDS), this paper analysed 464 313 substantiated child maltreatment reports to determine (i) the proportion and characteristics of reports involving substance abuse; and (ii) the child and caregiver/perpetrator (C/P) characteristics that predicted referral to treatment as recorded in service plans. Findings indicate that 12% (N = 53 234) of maltreatment reports involved C/P SUD. Yet, of those reports, only (19%) (N = 10 088) were referred to substance abuse treatment as part of their service plan, indicating a large gap between those who need treatment and those who receive it. This finding is important given that parental SUD is consistently linked to poorer child outcomes. Amongst other variables, reports indicate that C/P with co‐occurring emotional disturbance were three times more likely to be referred to treatment for SUD as part of service plans. Additional research is needed regarding the characteristics that distinguish C/P who receive referrals for SUD treatment in substantiated cases of child maltreatment. 相似文献
30.
《Journal of social service research》2013,39(4):99-107
No abstract available for this article. 相似文献