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Research on the Dynamic Characteristics of the Hybrid Aerial Underwater Vehicle: Low-velocity Water Exit
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作者 Honglu Yun Yufei Jin +2 位作者 Hongfei Xie Zheng Zeng Lian Lian 《哈尔滨工程大学学报(英文版)》 2025年第2期323-330,共8页
This study investigates the hydrodynamic process of a cylinder ejected from the water’s surface through high-speed camera experiments.Using digital image processing methods,the images obtained through experiments are... This study investigates the hydrodynamic process of a cylinder ejected from the water’s surface through high-speed camera experiments.Using digital image processing methods,the images obtained through experiments are processed and analyzed.Although the dynamics of rising buoyant cylinders have been thoroughly investigated,the pop-up height of the cylinders has not been extensively explored.Statistical analysis of the kinematic and dynamic data of cylinders is conducted.Research has shown that after the cylinder rises,it pops out of the water’s surface.Within the experimental range,the pop-up height of the cylinder is related to the release depth.Furthermore,the pop-up height and release depth of the cylinder vary linearly under vertical release conditions.Under horizontal release conditions,the relationship between pop-up height and release depth shows irregular changes mainly because of the unstable shedding of the wake vortex. 展开更多
关键词 Low-velocity Water exit CYLINDER Pop-up height OSCILLATION
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Consequences of Political Exits on Capital Structure:Brexit Case
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作者 Mohamad Youness 《Economics World》 2025年第4期301-316,共16页
The paper addresses the impacts of political exits on capital structure policies,through studying the impact of the Brexit deal on the UK's companies listed at FTSE 100 as a practical case.The study is divided int... The paper addresses the impacts of political exits on capital structure policies,through studying the impact of the Brexit deal on the UK's companies listed at FTSE 100 as a practical case.The study is divided into two periods:the first before the Brexit deal(2010-2015)and the second after the referendum until Brexit(2016-2021).Data were collected from the annual reports of the UK companies and the FTSE 100 database.Moreover,capital structure policies were studied by analyzing the determinants such as long-term debt over total equity,profitability,tangibility,liquidity,propensity to pay dividends,size,and political factor-Brexit.The results show that there is a direct relationship between political exits and capital structure.Also,the results show that the financial ratios are different between the two periods(before and after Brexit),where it seems that the capital structure variables were affected starting from the referendum period,political negotiations between the two parties,and then Brexit(2016-2021).In addition,the correlation matrix shows that long-term debt over total equity has a negative correlation with profitability,liquidity,and political factors,where it seems that long-term debt over total equity has a positive correlation with tangibility,size,and paying dividends.Moreover,the results show that political shocks were affecting the FTSE 100 performance starting from 2016 until 2021.The study could be useful for financial and economic academics.Moreover,the study could be helpful for EU members and the UK government,taking into consideration the interests of the UK and EU where any future policies or laws will affect the financial and economic sectors of the two parties. 展开更多
关键词 capital structure UNCERTAINTY political exits Brexit FTSE 100
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CFD–FEM analysis of ice-impact effect on the water-exit cavity and hydrodynamic characteristics of a ventilated vehicle
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作者 Hao Wang Xiaowei Cai +4 位作者 Zhihua Chen Yihang Wang Yuan Liu Wenjun Yi Zhengui Huang 《Defence Technology(防务技术)》 2025年第11期204-222,共19页
Understanding the evolution mechanisms of water-exit cavities and flow fields evolve during highintensity interactions between vehicles and floating ice is critical for advancing the application of submarine-launched ... Understanding the evolution mechanisms of water-exit cavities and flow fields evolve during highintensity interactions between vehicles and floating ice is critical for advancing the application of submarine-launched marine equipment in low-temperature ice-prone waters.A computational fluid dynamics-finite element method(CFD-FEM) coupled framework was established to simulate bidirectional fluid-structure interactions during the water-exit process of a ventilated vehicle impacting ice in brash environments.Distinct evolution characteristics were revealed by comparatively analyzing the cavity,flow fields,hydrodynamic loading,structural deformation,and trajectory stability across three scenarios:ice-free,single-ice,and multi-ice.Furthermore,the position-dependent impact effects were characterized.The findings reveal that the impact,friction,and compression effects of ice induce bending and wrinkling of the shoulder cavity,aggravating its collapse and increasing the wetting of the vehicle,resulting in a substantial expansion of the high-velocity and vortex-dominated regions within the flow field,accompanied by more obvious water splashes.The impact of ice notably increases the kinetic energy dissipation of the vehicle during the cross-water stage and diminishes its motion stability.In the center-symmetric layout,the vehicle collides with ice only once,with high stress confined to the head.Conversely,the radial-offset layout causes secondary or even multiple collisions,resulting in high-stress areas on the shoulder of the vehicle,making it deflect and ultimately causing the tail cavity to tilt and become destabilized.The design of new vehicles suitable for ice-prone environments should focus on enhancing the impact toughness of the head structure and optimizing the surface shape design to improve the adaptability to low-temperature complex environments. 展开更多
关键词 Water exit Cavity evolution Motion characteristics Floating ice Impact load Fluid-structure coupling
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Two-Stage Early Exiting From Globality Towards Reliability
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作者 Jianing He Qi Zhang +1 位作者 Hongyun Zhang Duoqian Miao 《CAAI Transactions on Intelligence Technology》 2025年第4期1019-1032,共14页
Early exiting has shown significant potential in accelerating the inference of pre-trained language models(PLMs)by allowing easy samples to exit from shallow layers.However,existing early exiting methods primarily rel... Early exiting has shown significant potential in accelerating the inference of pre-trained language models(PLMs)by allowing easy samples to exit from shallow layers.However,existing early exiting methods primarily rely on local information from individual samples to estimate prediction uncertainty for making exiting decisions,overlooking the global information provided by the sample population.This impacts the estimation of prediction uncertainty,compromising the reliability of exiting de-cisions.To remedy this,inspired by principal component analysis(PCA),the authors define a residual score to capture the deviation of features from the principal space of the sample population,providing a global perspective for estimating prediction uncertainty.Building on this,a two-stage exiting strategy is proposed that integrates global information from residual scores with local information from energy scores at both the decision and feature levels.This strategy incorporates three-way decisions to enable more reliable exiting decisions for boundary region samples by delaying judgement.Extensive experiments on the GLUE benchmark validate that the method achieves an average speed-up ratio of 2.17×across all tasks with minimal per-formance degradation.Additionally,it surpasses the state-of-the-art E-LANG by 11%in model acceleration,along with a performance improvement of 0.6 points,demonstrating a better performance-efficiency trade-off. 展开更多
关键词 early exiting inference acceleration pre-trained language model principal component analysis three-way decisions
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Prudence is never excessive:Caution warranted in 5-aminosalicylic acid derivatives withdrawal for ulcerative colitis
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作者 Antonietta Gerarda Gravina Raffaele Pellegrino Alessandro Federico 《World Journal of Gastroenterology》 2025年第44期173-177,共5页
This invited commentary discusses the recent study by Atay et al,which investigated relapse rates following the spontaneous withdrawal of maintenance 5-aminosalicylates in ulcerative colitis.The discussion focuses,in ... This invited commentary discusses the recent study by Atay et al,which investigated relapse rates following the spontaneous withdrawal of maintenance 5-aminosalicylates in ulcerative colitis.The discussion focuses,in this patient setting,on the possible reasons that might prompt clinicians to pursue such exit strategies,and on the importance of exercising caution in these decisions,given the extremely narrow subsets of patients for whom international guidelines allow any degree of leeway. 展开更多
关键词 Ulcerative colitis Inflammatory bowel disease 5-aminosalicylic acid derivatives WITHDRAWAL Exit strategy
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具有不等错误保护特性的LDPC编码调制方案 被引量:4
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作者 张玉玲 袁东风 程翔 《通信学报》 EI CSCD 北大核心 2006年第12期98-102,共5页
针对LDPC(low-densityparity-check)编码调制系统,提出了一种新的具有不等错误保护特性的调制方案,在一个码字内,利用不同的调制方式对于重要的比特给予较强的保护,对于次要的比特给予较弱的保护,该方案既适用于非规则LDPC码,也适用于规... 针对LDPC(low-densityparity-check)编码调制系统,提出了一种新的具有不等错误保护特性的调制方案,在一个码字内,利用不同的调制方式对于重要的比特给予较强的保护,对于次要的比特给予较弱的保护,该方案既适用于非规则LDPC码,也适用于规则LDPC码。计算机仿真结果表明,新方案的性能是传统16QAM及4QAM的折衷,当采用1/2码率时,其频带利用率与8PSK相同,但是误码率性能优于8PSK。新方案的性能优于现有文献中基于比特可靠性的调制映射方案,并采用EXIT(extrinsicinformationtransfer)图对新方案的优异性能给出了解释。 展开更多
关键词 LDPC码 不等错误保护 EXIT图
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一种AWGN信道下非规则LDPC码的优化方法 被引量:5
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作者 毛倩 董德存 曾小清 《计算机应用》 CSCD 北大核心 2010年第2期292-294,共3页
提出了一种加性高斯噪声(AWGN)信道下非规则低密度奇偶校验(LDPC)码的优化方法。利用LDPC码迭代译码算法下变量节点与校验节点的EX IT曲线之间的面积反映码的收敛阈值与香农限的差距这一特点,设计表示两条EX IT曲线之间面积的函数F,该... 提出了一种加性高斯噪声(AWGN)信道下非规则低密度奇偶校验(LDPC)码的优化方法。利用LDPC码迭代译码算法下变量节点与校验节点的EX IT曲线之间的面积反映码的收敛阈值与香农限的差距这一特点,设计表示两条EX IT曲线之间面积的函数F,该函数可以衡量非规则LDPC码的性能,F值越小,LDPC码的收敛阈值就越接近香农限。仿真显示,合理设计变量节点和校验节点,减小函数F的值,能够提高非规则LDPC码的性能。 展开更多
关键词 低密度奇偶校验码 外部信息转换(EXIT)图 加性高斯白噪声 迭代译码 收敛阈值
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GF(q)域上非规则LDPC码EXIT图分析方法研究 被引量:2
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作者 许拔 张仲明 +1 位作者 何英亮 张尔扬 《计算机工程与科学》 CSCD 北大核心 2011年第5期177-182,共6页
GF(q)域上非规则LDPC码是二进制非规则LDPC码在有限域GF(q=2p)上的扩展,在码长和码率相等的情况下,具有比二进制非规则LDPC码更优异的性能。如何分析GF(q)域上非规则LD-PC码的迭代译码性能是其能否有效应用的关键。基于迭代译码结构,本... GF(q)域上非规则LDPC码是二进制非规则LDPC码在有限域GF(q=2p)上的扩展,在码长和码率相等的情况下,具有比二进制非规则LDPC码更优异的性能。如何分析GF(q)域上非规则LD-PC码的迭代译码性能是其能否有效应用的关键。基于迭代译码结构,本文研究了AWGN信道下GF(q)域上非规则LDPC码的EXIT图分析方法,推导了其计算表达式;提出了利用EXIT图变量节点与校验节点联合优化准则。仿真结果表明,相对密度进化方法,该方法计算出的收敛门限值的精度稍有下降,却极大地降低了计算复杂度;在相同通信条件下,通过联合优化准则设计的GF(q)域上的非规则LDPC性能优于二进制非规则LDPC码;得到的收敛门限对应的信噪比非常接近香农限,进一步验证了EXIT图分析工具的优越性。 展开更多
关键词 非规则LDPC 密度进化 EXIT 收敛门限值 GF(q) 香农限
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低密度校验码(LDPC码) 被引量:2
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作者 曹海燕 李君 韦岗 《电路与系统学报》 CSCD 北大核心 2008年第2期95-103,78,共10页
低密度校验码(Low Density Parity Check Codes,LDPCcodes)是当前编码理论领域研究最热的信道编码之一。本文首先对信道编码研究历程作了简单回顾,然后介绍了LDPC码的发展历程并全面介绍了其相关理论。对LDPC码的和积译码算法(Sum-Produ... 低密度校验码(Low Density Parity Check Codes,LDPCcodes)是当前编码理论领域研究最热的信道编码之一。本文首先对信道编码研究历程作了简单回顾,然后介绍了LDPC码的发展历程并全面介绍了其相关理论。对LDPC码的和积译码算法(Sum-Product Algorithm,SPA)或置信传播算法(Belief Propagation Algorithm,BPA)、基于二分图的随机构造与代数构造、密度进化理论、高斯近似以及EXIT表分析等相关技术理论的发展和原理进行了详尽的阐述。同时本文还给出近年来LDPC码最新研究成果并给出一些开放性的研究课题。 展开更多
关键词 LDPC码 置信传播 和积译码 构造 密度进化 高斯近似 EXIT
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基于EXIT图的正则LDPC码性能分析研究 被引量:3
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作者 徐华 徐澄圻 《计算机工程与应用》 CSCD 北大核心 2007年第18期53-55,81,共4页
EXIT(EXtrinsic Information Transfer)图分析方法可以看作密度进化技术的一种简化,具有实现简单的优点,并且在不同的信道、调制方案以及检测器中都可以使用。在详细阐述了EXIT图分析方法的基础上,给出了基于EXIT图的正则LDPC码的门限... EXIT(EXtrinsic Information Transfer)图分析方法可以看作密度进化技术的一种简化,具有实现简单的优点,并且在不同的信道、调制方案以及检测器中都可以使用。在详细阐述了EXIT图分析方法的基础上,给出了基于EXIT图的正则LDPC码的门限判决算法,进一步通过计算机仿真分别给出了变量节点译码器和校验节点译码器的EXIT曲线,以及不同的信道信噪比下(3,6)正则LDPC码EXIT图的变化规律,直观地对迭代译码过程中的互信息变化进行了描述分析。 展开更多
关键词 LDPC码 互信息 EXIT图 噪声门限判决算法
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基于EXIT图的Turbo均衡LDPC码性能分析及优化研究 被引量:1
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作者 徐华 徐澄圻 《信号处理》 CSCD 北大核心 2007年第3期388-393,共6页
EXIT图是用来分析级联系统中外信息迭代交换的重要工具,本文将Brink的基于EXIT图的优化MIMO信道LDPC码的思想推广到用于Turbo均衡的LDPC码性能分析及码结构设计优化中。文章首先给出了基于互信息的接收机具体分析模型,接着分别讨论了接... EXIT图是用来分析级联系统中外信息迭代交换的重要工具,本文将Brink的基于EXIT图的优化MIMO信道LDPC码的思想推广到用于Turbo均衡的LDPC码性能分析及码结构设计优化中。文章首先给出了基于互信息的接收机具体分析模型,接着分别讨论了接收机分析模型中两个单元的EXIT曲线:线性MMSE均衡器和VND(variable node decoder)的联合EXIT曲线,CND(check node variable)的EXIT曲线的详细计算步骤。进一步以获得的EXIT曲线为基础,提出了用于Tur- bo均衡的LDPC码的码结构优化算法,EQVAC-EXIT(EQVAC:equalizer VND and CND)算法,算法能够自动地进行码集噪声门限值计算及优化次数分布对的搜索。最后的数值仿真结果表明,(3,6)正则码及优化得到的非正则码的噪声门限值距离Narayanan的结果仅相差0.03dB左右,优化得到的边的次数分布及节点的次数分布与Narayanan的结果相比也很接近。 展开更多
关键词 EXIT图 码结构优化 MMSE均衡 EQVAC-EXIT算法
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Discussion on Calculation Method of Poverty Incidence in the Exit Evaluation of Poverty-Stricken Counties and Villages 被引量:4
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作者 杨子生 《Agricultural Science & Technology》 CAS 2017年第9期1766-1769,共4页
Poverty incidence is the key index that needs to be measured in the poverty exit examination and evaluation of 832 poverty-stricken counties and 128 000 poverty-stricken villages. In this paper, based on the statement... Poverty incidence is the key index that needs to be measured in the poverty exit examination and evaluation of 832 poverty-stricken counties and 128 000 poverty-stricken villages. In this paper, based on the statement of general concept and conventional calculation method of the poverty incidence, the calculation method of poverty incidence in the exit evaluation of poverty-stricken counties (also including poverty-stricken township and poverty-stricken villages) was investigated through the view of the third-party evaluation. In addition to considering the previous "number of planned poverty remaining population", the method also needed to give consideration to the exiting mistaken population, evaluation missing population. Based on the case in Yuanyang County, Honghe Hani and Yi Autonomous Prefecture, Yunnan Province, the poverty incidences of 10 exit planning villages by the end of 2017 in Yuanyang County were investigated and estimated, and suggestions were proposed to promote the precise poverty alleviation and poverty relief of the county. 展开更多
关键词 Poverty-stricken county EXIT Evaluation Poverty incidence Calculation method
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基于LDPC的BICM系统星座映射方式分析 被引量:2
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作者 赵传钢 林家儒 吴伟陵 《无线电工程》 2006年第11期10-12,52,共4页
星座映射方式在BICM系统的设计中非常重要。将外信息传递函数(Extrinsic Information Transfer Function)曲线用于星座映射的设计,用Monte Carlo仿真给出了16QAM星座的几种星座映射方式的外信息传递函数曲线,结合EXIT曲线分析了星座映... 星座映射方式在BICM系统的设计中非常重要。将外信息传递函数(Extrinsic Information Transfer Function)曲线用于星座映射的设计,用Monte Carlo仿真给出了16QAM星座的几种星座映射方式的外信息传递函数曲线,结合EXIT曲线分析了星座映射方式对系统性能的影响。仿真结果证实了EXIT曲线在星座映射设计中的有效性。 展开更多
关键词 比特交织编码调制 LDPC码 星座映射 外信息传递函数(EXIT)
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EXIT治疗胎儿颈胸部巨大包块1例
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作者 梁志清 常青 +10 位作者 李俊男 陈功立 杨康 廖克龙 熊刚 陶国才 张铭 毕敏 何念海 尹晓娟 王昱 《第三军医大学学报》 CAS CSCD 北大核心 2006年第23期2322-2322,2326,共2页
关键词 EXIT 淋巴管瘤
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基于EXIT图和自适应微粒群算法的度分布对优化方法
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作者 姬红兵 李佳 张桂华 《电子与信息学报》 EI CSCD 北大核心 2009年第8期2011-2014,共4页
综合EXIT图法和自适应微粒群优化(APSO)算法的优点,该文提出了一种基于EXIT图和APSO算法的非正则LDPC码度分布对优化方法。该方法设计了衡量EXIT曲线匹配程度的全局代价函数,并运用APSO算法对度分布对进行快速迭代优化,迭代过程中不需... 综合EXIT图法和自适应微粒群优化(APSO)算法的优点,该文提出了一种基于EXIT图和APSO算法的非正则LDPC码度分布对优化方法。该方法设计了衡量EXIT曲线匹配程度的全局代价函数,并运用APSO算法对度分布对进行快速迭代优化,迭代过程中不需要固定CND曲线,可以获得EXIT曲线更加匹配的优化度分布对,以及更高的噪声门限。仿真结果表明,该方法在码结构优化方面有着很好的性能,且优化速度较高斯逼近法有了较大提高。 展开更多
关键词 LDPC码 EXIT图 自适应微粒群优化 APSO-EXIT算法
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LDPC码设计方法研究进展 被引量:1
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作者 徐华 《科技创新导报》 2007年第33期1-1,3,共2页
要获得好的LDPC码,码的结构设计最为关键。文章首先介绍了影响码性能因素的几个重要的参数,码结构设计的出发点是影响码性能的因素;接着从目前主要的两种结构设计研究方向出发,就基于随机方法的码的构造,基于代数方法的准循环LDPC码的... 要获得好的LDPC码,码的结构设计最为关键。文章首先介绍了影响码性能因素的几个重要的参数,码结构设计的出发点是影响码性能的因素;接着从目前主要的两种结构设计研究方向出发,就基于随机方法的码的构造,基于代数方法的准循环LDPC码的构造设计这两个方面的研究进行了综述。 展开更多
关键词 密度进化 EXIT图 QC-LDPC码 代数构造
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两种级联空时格码方案的EXIT分析
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作者 杨海芬 郝黎宏 +2 位作者 李广军 熊勇 林文峰 《电子技术应用》 北大核心 2009年第3期97-99,103,共4页
级联空时格码方案可以有效地提高空时格码系统的性能。研究了两种级联空时格码方案:PC-STTC和ST-Turbo-TC。由于两种级联方案都使用了迭代译码方法,而外信息转移(EXIT)图是分析迭代译码性能的有利工具,主要分析比较了PC-STTC和ST-Turbo... 级联空时格码方案可以有效地提高空时格码系统的性能。研究了两种级联空时格码方案:PC-STTC和ST-Turbo-TC。由于两种级联方案都使用了迭代译码方法,而外信息转移(EXIT)图是分析迭代译码性能的有利工具,主要分析比较了PC-STTC和ST-Turbo-TC的EXIT性能,比较了不同信噪比和编码多项式对于译码外信息转移特性的影响。研究结果显示,PC-STTC方案比ST-Turbo-TC方案有着更好的迭代收敛性能,同时给出了BER仿真图证明了EXIT图的分析结论。 展开更多
关键词 EXIT图 空时格码 迭代译码 收敛性
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基于逐分量软干扰删除的迭代线性检测算法
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作者 李秀丽 张益农 +1 位作者 周进 戴晓明 《计算机工程与科学》 CSCD 北大核心 2015年第7期1239-1244,共6页
提出了一种新型基于调制符号的分量进行干扰删除和线性最小均方误差滤波的软输入软输出检测算法,并采用软输入软输出的多入多出MIMO检测器和信道编码串行级联的迭代检测译码IDD结构。该算法充分利用正交调制符号同相分量和正交分量的独... 提出了一种新型基于调制符号的分量进行干扰删除和线性最小均方误差滤波的软输入软输出检测算法,并采用软输入软输出的多入多出MIMO检测器和信道编码串行级联的迭代检测译码IDD结构。该算法充分利用正交调制符号同相分量和正交分量的独立衰落特性,达到检测中更加准确的软干扰删除。外信息转移EXIT图表明该算法比传统的逐符号软删除算法具有更低的临界信噪比。数值仿真也验证了提出的基于调制符号的分量删除的线性检测算法比采用调制符号级的删除具有更优的误码性能,并且仍然具有低复杂度的特性。 展开更多
关键词 逐分量软干扰删除(CLSC) 多入多出(MIMO) 外信息转移图(EXIT) 迭代检测译码(IDD)
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LDPC码EXIT曲线图分析方法研究
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作者 徐富兵 雷菁 +1 位作者 李二保 贺文辉 《无线电通信技术》 2008年第2期18-21,共4页
EXIT曲线图是ten Brink发明的分析迭代和积译码收敛性能的有效工具。在描述了LDPC码迭代译码器结构基础上,详细地推导和研究了在AWGN信道中EXIT曲线图性能分析方法的计算方法。利用此方法确定了多种度分布LDPC码的收敛门限,并与利用高... EXIT曲线图是ten Brink发明的分析迭代和积译码收敛性能的有效工具。在描述了LDPC码迭代译码器结构基础上,详细地推导和研究了在AWGN信道中EXIT曲线图性能分析方法的计算方法。利用此方法确定了多种度分布LDPC码的收敛门限,并与利用高斯近似和密度进化得到的仿真结果进行比较分析,探讨EXIT曲线图的优点和进一步应用前景。 展开更多
关键词 EXIT曲线图 LDPC码 和积译码 收敛门限
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Holographic Goggles Optical System
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作者 陈晃明 《Journal of Beijing Institute of Technology》 EI CAS 1992年第1期31-34,共4页
Based on the holographic theory, a pair of reflective holographic lenses have been utilized with an aim to improve the optical properties of night vision goggles. The aberration distribution of the holographic lens ha... Based on the holographic theory, a pair of reflective holographic lenses have been utilized with an aim to improve the optical properties of night vision goggles. The aberration distribution of the holographic lens has been confirmed by experiments and compensated by a conventional symmetrical spherical system. Resulting data of the whole optical system are given. 展开更多
关键词 image intensifiers grlatin/holographic goggles roof mirror exit pupil
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