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A general purpose exact Rayleigh scattering look-up table for ocean color remote sensing 被引量:5
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作者 HE Xianqiang PAN Delu +1 位作者 BAI Yan GONG Fang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2006年第1期48-56,共9页
The current exact Rayleigh scattering calculation of ocean color remote sensing uses the look-up table (LUT), which is usually created for a special remote sensor and cannot be applied to other sensors. For practica... The current exact Rayleigh scattering calculation of ocean color remote sensing uses the look-up table (LUT), which is usually created for a special remote sensor and cannot be applied to other sensors. For practical application, a general purpose Rayleigh scattering LUT which can be applied to all ocean color remote sensors is generated. An adding-doubling method to solve the vector radiative transfer equation in the plane-parallel atmosphere is deduced in detail. Compared with the exact Rayleigh scattering radiance derived from the MODIS exact Rayleigh scattering LUT, it is proved that the relative error of Rayleigh scattering calculation with the adding-doubling method is less than 0.25%, which meets the required accuracy of the atmospheric correction of ocean color remote sensing. Therefore, the adding-doubling method can be used to generate the exact Rayleigh scattering LUT for the ocean color remote sensors. Finally, the general purpose exact Rayleigh scattering LUT is generated using the adding-doubling method. On the basis of the general purpose LUT, the calculated Rayleigh scattering radiance is tested by comparing with the LUTs ofMODIS, SeaWiFS and the other ocean color sensors, showing that the relative errors are all less than 0.5%, and this general purpose LUT can be applied to all ocean color remote sensors. 展开更多
关键词 ocean color Rayleigh scattering look-up table radiative transfer adding-doubling method
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Fine Doppler shift acquisition algorithm for BeiDou software receiver by a look-up table 被引量:4
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作者 QIU Wenqi ZENG Qingxi +1 位作者 GAO Chang LYU Chade 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2020年第3期612-625,共14页
The BeiDou software receiver uses the fast Fourier transform(FFT)to perform the acquisition.The Doppler shift estimation accuracy should be less than 500 Hz to ensure satellite signals to enter a locked state in the t... The BeiDou software receiver uses the fast Fourier transform(FFT)to perform the acquisition.The Doppler shift estimation accuracy should be less than 500 Hz to ensure satellite signals to enter a locked state in the tracking loop.Since the frequency step is usually 500 Hz or larger,the Doppler shift estimation accuracy cannot guarantee that satellite signals are brought into a stable tracking state.The straightforward solutions consist in increasing the sampling time and using zero-padding to improve the frequency resolution of the FFT.However,these solutions intensify the complexity and amount of computation.The contradiction between the acquisition accuracy and the computational load leads us to research for a more simple and effective algorithm,which achieves fine acquisition by a look-up table.After coarse acquisition using the parallel frequency acquisition(PFA)algorithm,the proposed algorithm optimizes the Doppler shift estimation through the look-up table method based on the FFT results to improve the acquisition accuracy of the Doppler shift with a minimal additional computing load.When the Doppler shift is within the queryable range of the table,the proposed algorithm can improve the Doppler shift estimation accuracy to 50 Hz for the BeiDou B1I signal. 展开更多
关键词 fine acquisition fast Fourier transform(FFT) table look-up parallel frequency acquisition(PFA) BEIDOU
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Performance of global look-up table strategy in digital image correlation with cubic B-spline interpolation and bicubic interpolation 被引量:5
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作者 Zhiwei Pan Wei Chen +3 位作者 Zhenyu Jiang Liqun Tang Yiping Liu Zejia Liu 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2016年第3期126-130,共5页
Global look-up table strategy proposed recently has been proven to be an efficient method to accelerate the interpolation, which is the most time-consuming part in the iterative sub-pixel digital image correlation (... Global look-up table strategy proposed recently has been proven to be an efficient method to accelerate the interpolation, which is the most time-consuming part in the iterative sub-pixel digital image correlation (DIC) algorithms. In this paper, a global look-up table strategy with cubic B-spline interpolation is developed for the DIC method based on the inverse compositional Gauss-Newton (IC-GN) algorithm. The performance of this strategy, including accuracy, precision, and computation efficiency, is evaluated through a theoretical and experimental study, using the one with widely employed bicubic interpolation as a benchmark. The global look-up table strategy with cubic B-spline interpolation improves significantly the accuracy of the IC-GN algorithm-based DIC method compared with the one using the bicubic interpolation, at a trivial price of computation efficiency. 展开更多
关键词 Digital image correlation Inverse compositional Gauss-Newton algorithm Cubic B-spline interpolation Bicubic interpolation Global look-up table
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Accelerated generation of holograms with ultra-low memory symmetrically high-compressed look-up table
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作者 杨燕 朱建英 +1 位作者 孙敏远 毕勇 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期466-471,共6页
Computer-generated holography technology has been widely applied,and as research in this field deepens,the demand for memory and computational power in small AR and VR devices continues to increase.This paper presents... Computer-generated holography technology has been widely applied,and as research in this field deepens,the demand for memory and computational power in small AR and VR devices continues to increase.This paper presents a hologram generation method,i.e.,a symmetrically high-compressed look-up table method,which can reduce memory usage by50%.In offline computing,half of the basic horizontal and vertical modulation factors are stored,halving the memory requirements without affecting inline speed.Currently,its potential extends to various holographic applications,including the production of optical diffraction elements. 展开更多
关键词 computergenerated hologram look-up table HOLOGRAPHY
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Research of NO_(2) vertical profiles with look-up table method based on MAX-DOAS
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作者 Yingying Guo Suwen Li +2 位作者 Fusheng Mou Hexiang Qi Qijin Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第1期332-338,共7页
Obtaining the vertical distribution profile of trace gas is of great significance for studying the diffusion procedure of air pollution.In this article,a look-up table method based on multi-axis differential optical a... Obtaining the vertical distribution profile of trace gas is of great significance for studying the diffusion procedure of air pollution.In this article,a look-up table method based on multi-axis differential optical absorption spectroscopy(MAX-DOAS)technology is established for retrieving the tropospheric NO_(2) vertical distribution profiles.This method retrieves the aerosol extinction profiles with minimum cost function.Then,the aerosol extinction profiles and the atmospheric radiation transfer model(RTM)are employed to establish the look-up table for retrieving the NO_(2) vertical column densities(VCDs)and profiles.The measured NO_(2) differential slant column densities(DSCDs)are compared with the NO_(2) DSCDs simulated by the atmospheric RTM,and the NO_(2) VCDs,the weight factor of NO_(2) in the boundary layer,and the boundary layer height are obtained by the minimization process.The look-up table is established to retrieve NO_(2) VCDs based on MAX-DOAS measurements in Huaibei area,and the results are compared with the data from Copernicus Atmospheric Monitoring Service(CAMS)model.It is found that there are nearly consistent and the correlation coefficient R2 is more than 0.86.The results show that this technology provides a more convenient and accurate retrieval method for the stereoscopic monitoring of atmospheric environment. 展开更多
关键词 multi-axis differential optical absorption spectroscopy look-up table method the cost function NO_(2)vertical profile
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The Influence Function of the Correlation Indexes in a Two-by-Two Table
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作者 Giovanni Girone Fabio Manca Claudia Marin 《Applied Mathematics》 2014年第21期3411-3420,共10页
In this paper we examine 5 indexes (the two Yule’s indexes, the chi square, the odds ratio and an elementary index) of a two-by-two table, which estimate the correlation coefficient ρ in a bivariate Bernoulli distri... In this paper we examine 5 indexes (the two Yule’s indexes, the chi square, the odds ratio and an elementary index) of a two-by-two table, which estimate the correlation coefficient ρ in a bivariate Bernoulli distribution. We will find the compact expression of the influence functions, which allow the quantification of the effect of an infinitesimal contamination of the probability of any pair of attributes of the bivariate random variable distributed according to the above-mentioned model. We prove that the only unbiased index is the chi square. In order to determine the indexes, which are less sensitive to contamination, we obtain the expressions of three synthetic measures of the influence function, which are the maximum contamination (gross sensitivity error), the mean square deviation and the variance. These results, even if don’t allow a definitive assessment of the overall optimum properties of the five indexes, as not all of them are unbiased, nevertheless they allow to appreciating the synthetic entity of the effect of the contaminations in the estimation of the parameter ρ of the bivariate Bernoulli distribution. 展开更多
关键词 Two-by-Two table Influence function Correlation Indexes GROSS Sensitivity Error Mean Square Deviation Asymptotic Variance
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WinoNet:Reconfigurable look-up table-based Winograd accelerator for arbitrary precision convolutional neural network inference
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作者 Wang Chengcheng Li He +3 位作者 Cao Yanpeng Song Changjun Yu Feng Tang Yongming 《Journal of Southeast University(English Edition)》 EI CAS 2022年第4期332-339,共8页
To solve the hardware deployment problem caused by the vast demanding computational complexity of convolutional layers and limited hardware resources for the hardware network inference,a look-up table(LUT)-based convo... To solve the hardware deployment problem caused by the vast demanding computational complexity of convolutional layers and limited hardware resources for the hardware network inference,a look-up table(LUT)-based convolution architecture built on a field-programmable gate array using integer multipliers and addition trees is used.With the help of the Winograd algorithm,the optimization of convolution and multiplication is realized to reduce the computational complexity.The LUT-based operator is further optimized to construct a processing unit(PE).Simultaneously optimized storage streams improve memory access efficiency and solve bandwidth constraints.The data toggle rate is reduced to optimize power consumption.The experimental results show that the use of the Winograd algorithm to build basic processing units can significantly reduce the number of multipliers and achieve hardware deployment acceleration,while the time-division multiplexing of processing units improves resource utilization.Under this experimental condition,compared with the traditional convolution method,the architecture optimizes computing resources by 2.25 times and improves the peak throughput by 19.3 times.The LUT-based Winograd accelerator can effectively solve the deployment problem caused by limited hardware resources. 展开更多
关键词 quantized neural networks look-up table(LUT)-based multiplier Winograd algorithm arbitrary precision
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Effects of telmisartan combined with nifedipine controlled release tablet on inflammatory factors, vascular endothelial function and left ventricular function in patients with coronary heart disease with mild to moderate hypertension
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作者 Feng Guo Bao-Wei Zhang Zheng-Yan Zhu 《Journal of Hainan Medical University》 2017年第20期14-18,共5页
Objective: To investigate the effect of telmisartan combined with Nifedipine Controlled Release Tablet on inflammatory factors, vascular endothelial function and left ventricular function in patients with coronary hea... Objective: To investigate the effect of telmisartan combined with Nifedipine Controlled Release Tablet on inflammatory factors, vascular endothelial function and left ventricular function in patients with coronary heart disease with mild to moderate hypertension. Methods:A total of 92 cases of patients with coronary heart disease with mild to moderate hypertension were selected as the object of observation, according to the random data table, they were divided into the control group (n=46) and observation group (n=46), and patients in the control group were treated with Nifedipine Controlled Release Table therapy, on this basis, the observation group patients were given telmisartan treatment, two groups were treated for 6 months. The levels of the blood pressure, inflammatory factors, vascular endothelial function and left ventricular function compared between the two groups before and after treatment. Results: There were no significant differences in the levels of SBP, DBP, hs-CRP, TNF-α, NO, ET-1, LVEF, LVEDD and LVESD in the two groups before treatment. After treatment, two groups of SBP, DBP, hs-CRP, TNF-α, ET-1, LVEDD and LVESD levels were significantly lower than those in the same group before treatment, and after treatment, the levels of SBP, DBP, hs-CRP, TNF-α, ET-1 and LVESD in the observation group were significantly lower than those in the control group, while there were no significant difference in the level of LVEDD between the two groups after treatment;Compared with level in the group before treatment, the levels of NO and LVEF in the two groups were significantly increased, and the observation group [(82.13±19.01) μmol/L, (52.83±7.45)%] was significantly higher than the control group ((67.37±13.08) μmol/L, (49.47±6.96)%)Conclusion: Telmisartan combined with Nifedipine Controlled Release Table in treating coronary heart disease with mild to moderate hypertension, can effectively control blood pressure, reduce the inflammatory stress, improve vascular endothelial function and left ventricular function of patients, has an important clinical value. 展开更多
关键词 Coronary heart disease with mild to moderate hypertension TELMISARTAN NIFEDIPINE Controlled Release table Inflammatory factors Vascular ENDOTHELIAL function Left VENTRICULAR function
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基于Linux的Netfilter/Iptables技术及其应用 被引量:2
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作者 卢朝晖 傅光轩 《海南师范学院学报(自然科学版)》 2003年第1期35-38,共4页
Netfilter/Iptables是一个集成在Linux内核中的IP数据包过滤系统.文章主要介绍了该 系统的两个基本组件及其基本工作原理,最后应用iptables工具建立一个简单的包过滤防火墙.
关键词 NETFILTER/IPtableS IP数据 包过滤系统 LINUX操作系统 包过滤防火墙 网络安全
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在Mathematica中用Table函数生成数组问题的探析
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作者 王荣波 《襄樊职业技术学院学报》 2011年第3期23-24,共2页
随着计算机的普及,数学用表逐渐成为历史。Mathematica强大的、高精度的数值计算功能为数学研究和数学实验提供了一个强有力的工具。因此探析在Mathematica中应用Table函数生成数组问题的格式、功能和适用范围就显得十分必要。
关键词 table函数 数组 数学实验 Mathematic
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Positive Stable Frailty Approach in the Construction of Dependence Life-Tables
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作者 Onchere Walter Weke Patrick +1 位作者 Joseph Ottieno Ogutu Carolyne 《Open Journal of Statistics》 2021年第4期506-523,共18页
Dependence may arise in insurance when the insureds are clustered into groups e.g. joint-life annuities. This dependence may be produced by sharing a common risk acting on mortality of members of the group. Various de... Dependence may arise in insurance when the insureds are clustered into groups e.g. joint-life annuities. This dependence may be produced by sharing a common risk acting on mortality of members of the group. Various dependence models have been considered in literature</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">;</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> however, the focus has been on either the lower-tail dependence alone or upper-tail dependence alone. This article implements the frailty dependence approach to life insurance problems where most applications have been within medical setting. Our strategy is to use the conditional independence assumption given an observed association measure in a positive stable frailty approach to account for both lower and upper-tail dependence. The model is calibrated on the association of Kenyan insurers 2010 male and female published rates. The positive stable model is then proposed to construct dependence life-tables and generate life annuity payment streams in the competitive Kenyan market. 展开更多
关键词 Joint-Life Annuity Life-table functions Shared Frailty Model Positive Stable Distribution Bayesian Inference
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Lowered water table causes species substitution while nitrogen amendment causes species loss in alpine wetland microbial communities
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作者 Yuntao LI Jin-Sheng HE +3 位作者 Hao WANG Jizhong ZHOU Yunfeng YANG Haiyan CHU 《Pedosphere》 SCIE CAS CSCD 2021年第6期912-922,共11页
Alpine wetlands are hotspots of carbon(C)storage and methane emission,and they could be key contributors to global warming.In recent years,rapid warming has lowered the water table in alpine wetlands on the Tibetan Pl... Alpine wetlands are hotspots of carbon(C)storage and methane emission,and they could be key contributors to global warming.In recent years,rapid warming has lowered the water table in alpine wetlands on the Tibetan Plateau,concurrent with intensified nitrogen(N)deposition via anthropogenic activities.We carried out a field experiment to investigate the ecological impacts of these two factors on soil bacterial and functional communities,which are essential drivers of greenhouse gas emissions.Nitrogen amendment alone decreased the phylogenetic alpha-diversity of bacterial communities which could be offset by lowered water table.In contrast,microbial functional alpha-diversity,revealed by a high-throughput microarray,remained unchanged.Both bacterial and functional beta-diversity responded to lowered water table,but only bacterial community responded to N amendment.The alpha-Proteobacteria,beta-Proteobacteria,and Bacteroidetes were the major responsive bacterial lineages,and C degradation,methanogenesis,alkaline shock,and phosphorus oxidation were the major responsive functional processes.Partitioning analysis revealed that N amendment changed bacterial community structure mainly via species loss processes but did not affect bacterial functional communities,with soil pH and ammonium as the key factors influencing changes in bacterial community structure.Conversely,lowered water table altered bacterial and functional communities through species substitution processes linked to soil pH and soil moisture.According to our results,the response mechanisms of microbial communities to lowered water table and N amendment are fundamentally different in alpine wetlands. 展开更多
关键词 alpha-diversity bacterial community beta-diversity microbial functional community N amendment water table lowering
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Evaluating logic functionality of cascaded frac
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作者 GUO Zhenhong LIN Yu +3 位作者 LI Tianyi JIA Rui GAO Tongqiang YANG Haigang 《太赫兹科学与电子信息学报》 2016年第3期474-480,共7页
Look Up Tables(LUTs) are the key components of Field-Programmable Gate Arrays(FPGAs)Many LUT architectures have been studied; nevertheless, it is difficult to quantificationally evaLUT based architecture. Traditionall... Look Up Tables(LUTs) are the key components of Field-Programmable Gate Arrays(FPGAs)Many LUT architectures have been studied; nevertheless, it is difficult to quantificationally evaLUT based architecture. Traditionally, dedicated efforts on specific modifications to the temapping tools are required for LUT architecture evaluation. A more feasible evaluation method forfunctionality is strongly required for the design of LUT architecture. In this paper, a mathematical for logic functionality calculation is proposed and conventional and fracturable LUT architectanalyzed. Furthermore, a cascaded fracturable LUT architecture is presented, which achieves twice functionality compared with the conventional LUTs and fracturable LUTs. 展开更多
关键词 Field PROGRAMMABLE GATE ARRAY cascaded Look Up tableS functionALITY evaluation
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k-阶旋转对称2-弹性函数的构造
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作者 刘春红 李龙飞 +3 位作者 高强 王天银 杜蛟 庞善起 《电子学报》 北大核心 2025年第5期1445-1452,共8页
基于支撑集交换技术,通过对k-阶旋转对称轨道的分析,给出了一个由n元1-阶旋转对称轨道,得到nk元k-阶旋转对称轨道的方法.进一步,通过改变定义在F_(2)^(nk)上的旋转对称弹性函数的支撑集,构造出新的k-阶旋转对称2-弹性函数,且至少能得到k... 基于支撑集交换技术,通过对k-阶旋转对称轨道的分析,给出了一个由n元1-阶旋转对称轨道,得到nk元k-阶旋转对称轨道的方法.进一步,通过改变定义在F_(2)^(nk)上的旋转对称弹性函数的支撑集,构造出新的k-阶旋转对称2-弹性函数,且至少能得到k·2^(k)个不同的nk(n≥3,k≥2)元k-阶旋转对称2-弹性函数. 展开更多
关键词 密码学 弹性函数 旋转对称函数 支撑矩阵 非线性度 代数次数
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基于截断表的保留格式加密算法TT-FPE 被引量:2
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作者 杨庆 田有亮 熊金波 《福建师范大学学报(自然科学版)》 北大核心 2025年第1期68-76,共9页
保留格式加密算法可以在加密的同时保证明文和密文格式相同,解决了信用卡号、电话号码、身份证号等敏感数据明文存储易造成隐私泄露等问题。当前保留格式加密方案大多基于Prefix、Cycle-Walking和Generalized-Feistel算法进行扩展和改进... 保留格式加密算法可以在加密的同时保证明文和密文格式相同,解决了信用卡号、电话号码、身份证号等敏感数据明文存储易造成隐私泄露等问题。当前保留格式加密方案大多基于Prefix、Cycle-Walking和Generalized-Feistel算法进行扩展和改进,存在多次调用Cycle-Walking结构的不确定性问题,同时,现有保留格式加密算法处理的问题域有一定的局限性。提出一种新型的基于截断表的保留格式加密算法,仅需调用一次Cycle-Walking结构,使加密结果落入问题域,以及在截断表算法基础上提出分段处理方案,进一步扩大了保留格式加密算法处理的问题域。并且通过安全性分析,证明了所提算法是安全的,能够抵御恶意敌手攻击。实验结果表明所提算法具有高效性,可将保留格式加密过程重复调用Cycle-Walking结构的次数降至0。且与先前保留格式加密算法相比,平均每字节加密开销相当。 展开更多
关键词 敏感信息 保留格式加密 FEISTEL结构 Cycle-Walking 截断表 随机函数
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共同富裕目标下的国民收入分配国际比较研究 被引量:1
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作者 唐雅 许宪春 王洋 《中国经济问题》 北大核心 2025年第2期42-56,共15页
如何在高质量发展中促进共同富裕,收入分配是关键问题。本文基于调整后国际可比口径资金流量表数据,对国民收入分配进行国际比较。研究发现:初次分配阶段,我国企业部门挤占了住户部门的初次分配总收入,资本要素相比劳动要素更为强势;再... 如何在高质量发展中促进共同富裕,收入分配是关键问题。本文基于调整后国际可比口径资金流量表数据,对国民收入分配进行国际比较。研究发现:初次分配阶段,我国企业部门挤占了住户部门的初次分配总收入,资本要素相比劳动要素更为强势;再分配阶段,我国社会保障及税收的再分配调节功能较弱;实物收入再分配阶段,我国实物社会转移占比偏低,实物福利对住户部门福利水平的提升作用有限。未来须完善按要素分配机制,优化税收、社保制度安排,重视实物福利支出对居民福利的促进作用,在高质量发展中促进共同富裕的实现。 展开更多
关键词 要素收入分配 共同富裕 资金流量表 国际比较 收入差距
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长白山阔叶红松林伴生树种色木槭的种群结构与动态 被引量:1
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作者 张金峰 李俊清 《生态学杂志》 北大核心 2025年第1期41-48,共8页
色木槭(Acer mono)为长白山北坡阔叶红松林主要伴生树种。本研究以色木槭种群为对象,通过样地调查和数据统计,编制种群静态生命表,拟合存活曲线、死亡率和消失率曲线,结合种群结构动态量化分析并应用4个生存函数和时间序列预测模型,分... 色木槭(Acer mono)为长白山北坡阔叶红松林主要伴生树种。本研究以色木槭种群为对象,通过样地调查和数据统计,编制种群静态生命表,拟合存活曲线、死亡率和消失率曲线,结合种群结构动态量化分析并应用4个生存函数和时间序列预测模型,分析色木槭种群结构与动态,揭示其生存现状,并预测未来发展趋势,以期为该种群的保护及阔叶红松林恢复提供参考依据。结果显示:色木槭种群年龄结构较为完整,Ⅰ~Ⅲ龄级个体在种群中占比重大(78.98%),说明种群具有较强的增长潜力;结合种群总体数量动态变化指数V_(pi)>V′_(pi)>0,可知色木槭种群为增长型。然而,种群存活曲线接近Deevey-Ⅲ型,说明幼龄个体大量死亡,反映出幼龄期是色木槭种群自身发展的瓶颈时期。生存函数分析显示,Ⅰ~Ⅵ龄级,种群呈增长趋势,在Ⅶ龄级达到平衡状态,而后进入衰退期。时间序列预测分析表明,色木槭种群各龄级个体数在未来2~10龄级时间内均稳定增加。本研究表明,阔叶红松林色木槭种群抗干扰能力较强,年龄结构较稳定,未来一段时间内,种群发展趋势良好。 展开更多
关键词 色木槭 静态生命表 数量动态分析 生存函数 时间序列预测
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面向向量部件的指数和对数函数优化方法
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作者 沈洁 龙标 +2 位作者 黄春 唐滔 彭林 《计算机工程与科学》 北大核心 2025年第1期18-26,共9页
指数和对数函数是浮点计算中重要的超越函数,在不同应用领域使用广泛。现代处理器向量寄存器宽度呈现逐代增加的趋势,为了进一步提高上层应用对向量部件的利用率,研究向量指数和对数函数优化方法具有重要的科学价值和现实意义。针对现... 指数和对数函数是浮点计算中重要的超越函数,在不同应用领域使用广泛。现代处理器向量寄存器宽度呈现逐代增加的趋势,为了进一步提高上层应用对向量部件的利用率,研究向量指数和对数函数优化方法具有重要的科学价值和现实意义。针对现有向量函数实现的性能瓶颈,设计和实现了面向向量部件的指数和对数函数优化方法,包括基于硬件加速指令的向量查表优化、分支优化和精度性能取舍优化。模拟器上的实验表明,优化实现的向量指数和对数函数均达到业界高精度标准,函数性能优于当前最佳开源实现,加速比达1.44以上。真实应用测试进一步表明,应用程序在优化的向量函数支持下可以实现高效向量化,相比原始标量实现平均性能提升达2.53倍。 展开更多
关键词 指数函数 对数函数 向量化 查表优化 硬件加速指令
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A Nonspherical Cloud Scattering Database Using Aggregates of Roughened Bullet Rosettes Model for the Advanced Radiative Transfer Modeling System(ARMS) 被引量:1
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作者 Ziyue HUANG Hanyu LU +4 位作者 Ziqiang MA Yining SHI Yang HAN Hao HU Jun YANG 《Advances in Atmospheric Sciences》 2025年第7期1483-1498,共16页
Accurate satellite data assimilation under all-sky conditions requires enhanced parameterization of scattering properties for frozen hydrometeors in clouds.This study aims to develop a nonspherical scattering look-up ... Accurate satellite data assimilation under all-sky conditions requires enhanced parameterization of scattering properties for frozen hydrometeors in clouds.This study aims to develop a nonspherical scattering look-up table that contains the optical properties of five hydrometeor types—rain,cloud water,cloud ice,graupel,and snow—for the Advanced Radiative Transfer Modeling System(ARMS)at frequencies below 220 GHz.The discrete dipole approximation(DDA)method is employed to compute the single-scattering properties of solid cloud particles,modeling these particles as aggregated roughened bullet rosettes.The bulk optical properties of the cloud layer are derived by integrating the singlescattering properties with a modified Gamma size distribution,specifically for distributions with 18 effective radii.The bulk phase function is then projected onto a series of generalized spherical functions,applying the delta-M method for truncation.The results indicate that simulations using the newly developed nonspherical scattering look-up table exhibit significant consistency with observations under deep convection conditions.In contrast,assuming spherical solid cloud particles leads to excessive scattering at mid-frequency channels and insufficient scattering at high-frequency channels.This improvement in radiative transfer simulation accuracy for cloudy conditions will better support the assimilation of allsky microwave observations into numerical weather prediction models.·Frozen cloud particles were modeled as aggregates of bullet rosettes and the optical properties at microwave range were computed by DDA.·A complete process and technical details for constructing a look-up table of ARMS are provided.·The ARMS simulations generally show agreement with observations of MWTS and MWHS under typhoon conditions using the new look-up table. 展开更多
关键词 nonspherical particles scattering look-up table discrete dipole approximation Advanced Radiative Transfer Modeling System
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偏转角度表与计算机辅助联合设计超声速风洞喷管 被引量:1
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作者 王洪悦 吕旸 +1 位作者 郭永博 弓震 《哈尔滨工程大学学报》 北大核心 2025年第3期550-557,共8页
针对超声速喷管设计中传统特征线法计算过程冗长复杂的问题,本文提出了一种基于偏转角度表的改进方法。结合计算机辅助设计技术,本文进一步提出了偏转角度表与计算机辅助设计联合设计喷管型线的方法,设计了适用于马赫数1~4工作范围的风... 针对超声速喷管设计中传统特征线法计算过程冗长复杂的问题,本文提出了一种基于偏转角度表的改进方法。结合计算机辅助设计技术,本文进一步提出了偏转角度表与计算机辅助设计联合设计喷管型线的方法,设计了适用于马赫数1~4工作范围的风洞喷管型线(测试区面积为1.4 m×1.4 m)。采用面积-马赫数理论公式对所设计的喷管型线进行了初步验证,并通过Matlab代码对设计喷管型线进行了比对分析。结果表明:通过引入偏转角度表,本文有效简化了特征线法的计算过程,显著提高了计算效率,计算时间缩短了80%以上。在相同的设计步骤下,采用偏转角度表与计算机辅助联合设计的喷管型线精度更高,且较代码设计的喷管型线避免了可能出现的缺陷,各喷管型线的误差均小于1%。本文提出的改进方法不仅提高了设计效率,而且确保了喷管型线的高精度。 展开更多
关键词 特征线法 偏转角度表 超声速流动 风洞喷管 普朗特-迈耶函数 计算机辅助设计 喷管型线 变马赫数
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