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Modeling industrial thickener using computational fluid dynamics(CFD),a case study:Tailing thickener in the Sarcheshmeh copper mine

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International Journal of Mining Science and Technology 2013年第6期23卷 885-892页

作者： Majid Ebrahimzadeh Gheshlaghi Ataallah Soltani Goharrizi Alireza Aghajani Shahrivar Hadi Abdollahi Department of Chemical Engineering College of EngineeringShahid Bahonar University of Kerman Mineral Processing Division Faculty of Mining EngineeringUniversity of Tehran

Separation of particles from liquid in the large gravitational tanks is widely used in mining and industrial wastewater treatment process.Thickener is key unit in the operational processes of hydrometallurgy and is used to separate solid from liquid.In this study,population balance models were combined with computational fluid dynamics(CFD)for modeling the tailing thickener.Parameters such as feed flow rate,flocculant dosage,inlet solid percent and feedwell were investigated.CFD was used to simulate the industrial tailing thickener with settled bed of 120 m diameter which is located in the Sarcheshmeh copper mine.Important factor of drag force that defines the rake torque of rotating paddles on the bed was also determined.Two phases turbulence model of Eulerian/Eulerian in accordance with turbulence model ofκ-ε.was used in the steady-state.Also population balance model consists of 15 groups of particle sizes with Luo and Lehr kernel was used for aggregation/breakage kernel.The simulation results showed good agreement with the operational data.

关键词： Thickener Feedwell Modeling Solid percent rake Torque

Mathematical Model and Machining Method for Spiral Flute rake Faces of Hourglass Worm Gear Hob

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第3期36卷 401-412页

作者： YANG Jie LI Haitao RUI Chengjie HUANG Yi ZHANG Xiaodi College of Engineering China Agricultural UniversityBeijing 100083P.R.China Key Laboratory of Optimal Design of Modern Agricultural Equipment in Beijing China Agricultural UniversityBeijing 100083P.R.China Beijing Kuiente Technology Co LtdBeijing 100043P.R.China

To improve the cutting performance of an hourglass worm gear hob and the accuracy of the resulting worm gear,the rake angles of the teeth on the pitch circle should be reduced.A method of forming the spiral flutes by using a variable transmission ratio was developed.This method ensures that the rake angles on the indexing torus of each tooth are approximately 0°.Based on the gear meshing theory and the hourglass worm forming method,the discretization mathematical model of the rake face of a planar double enveloping worm gear hob was established by using cylindrical generating surface,and the feed parameters for machining the rake face for a variable transmission ratio were obtained.The spiral flute was simulated and the hob was machined on a four axis CNC milling machine.A contourgraph was used to measure the rake angle.The measurement results showed that the proposed method can reduce the absolute value of the rake angle on both sides of the cutting teeth,which can be used for machining the spiral flute rake face of an hourglass worm gear hob.

关键词： hourglass worm gear hob cylindrical generating surface spiral flute rake face rake angle

一种基于rake结构的GNSS多径信号捕获方法

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仪器仪表学报 2010年第12期31卷 2854-2860页

作者：孙晓文张淑芳姜毅胡青大连海事大学信息科学与技术学院大连116026

为了提高多径环境下的GNSS接收机性能,在GNSS接收机设计中引入rake结构,提出一种基于rake结构的多径信号捕获方法。首先对GNSS系统中的多径信号特性及其对接收机性能的影响进行了分析。然后,在此基础上阐述基于rake结构的GNSS多径信号... 详细信息

为了提高多径环境下的GNSS接收机性能,在GNSS接收机设计中引入rake结构,提出一种基于rake结构的多径信号捕获方法。首先对GNSS系统中的多径信号特性及其对接收机性能的影响进行了分析。然后,在此基础上阐述基于rake结构的GNSS多径信号捕获方法原理,并给出该方法的具体实现过程。最后,通过仿真实验证明了该方法对GNSS信号中的多径成分具有有效的捕获能力,将该方法用于GNSS接收机后可以显著提高接收机的定位精度。

关键词：全球导航卫星系统 GNSS接收机 rake 多径信号捕获快速傅里叶变换

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室内环境下PAPM调制UWB误码性能分析

哈尔滨工程大学学报 2006年第5期27卷 676-680页

作者：王石记张乃通沙学军哈尔滨工业大学通信技术研究所黑龙江哈尔滨150001

分析了UWB室内衰落信道模型下脉冲幅度位置混合调制(PAPM)最优接收机性能.PAPM调制UWB系统的输入数据调制到脉冲的幅度和位置上.室内信道模型为IEEE802.15.3a提供的intel模型.通过rake接收机以最大比率(MRC)组合多径能量从而实现最优接... 详细信息

分析了UWB室内衰落信道模型下脉冲幅度位置混合调制(PAPM)最优接收机性能.PAPM调制UWB系统的输入数据调制到脉冲的幅度和位置上.室内信道模型为IEEE802.15.3a提供的intel模型.通过rake接收机以最大比率(MRC)组合多径能量从而实现最优接收.从理论上推导了在室内衰落信道条件下误码率(BER)的闭合表达式,从而分析了rake接收时UWB系统采用PAPM调制的极限性能.从数值结果可以看出,PAPM调制在保持BER性能不变的基础上,将通信速率提高了一倍.

关键词： UWB 多径 rake MRC PAPM

WCDMA系统中空时2D-rake接收机性能分析

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电波科学学报 2004年第5期19卷 519-524页

作者：张小飞徐大专杨蓓南京航空航天大学电子工程系南京210016

分析了在WCDMA系统的基站中采用含智能天线的空时 2D rake接收机的结构和性能。在建立了WCDMA信道、信号模型的基础上 ,给出了输出误码率的表达式。提出了一种新的利用两个连续时隙的导频符号估计出的信道参数进行加权最小二乘意义下二... 详细信息

分析了在WCDMA系统的基站中采用含智能天线的空时 2D rake接收机的结构和性能。在建立了WCDMA信道、信号模型的基础上 ,给出了输出误码率的表达式。提出了一种新的利用两个连续时隙的导频符号估计出的信道参数进行加权最小二乘意义下二次曲线内插的信道参数估计方法 (WLS)。仿真结果表明 :WLS算法能很好地跟踪多径衰落信道的变化 ,提出的空时 2Drake接收机的误码性能大大改善。

关键词： WCDMA rake 空时处理误码率信道估计

改进的基于二维扩频的WCDMA非rake接收机

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通信学报 2005年第11期26卷 93-99页

作者：唐友喜邵士海潘文生李少谦电子科技大学通信抗干扰技术国家级重点实验室四川成都610054

针对WCDMA发射的扩频信号,不同于传统的rake接收算法,本文采用变换域处理技术,提出了一种充分利用多径能量的二维扩频接收技术。分析了这种充分利用多径能量的二维扩频接收机的算法复杂度。通过计算机仿真,比较了传统的rake接收算法、... 详细信息

针对WCDMA发射的扩频信号,不同于传统的rake接收算法,本文采用变换域处理技术,提出了一种充分利用多径能量的二维扩频接收技术。分析了这种充分利用多径能量的二维扩频接收机的算法复杂度。通过计算机仿真,比较了传统的rake接收算法、充分利用多径能量的二维扩频接收算法的误码率性能。结果表明,在rake接收机难以精确分辨信道中的每条多径的情况下,使用充分利用多径能量的二维扩频接收机具有更好的误码率性能。

关键词：二维扩频 WCDMA rake 误码率

Evaluation of Downlink Performance of a Multiple-Cell, rake Receiver Assisted CDMA Mobile System

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Wireless Sensor Network 2010年第1期2卷 1-6页

作者： Ayodeji J. BAMISAYE Michael O. KOLAWOLE 不详

In wireless Code Division Multiple Access (CDMA) system, the use of power control is indispensable to combat near-far and fading problems. Signals transmitted over a multipath propagation channel which exhibits inter-path interference and fading. The receiver has to employ measures to mitigate these effects or it will incur severe performance degradation. A classic approach in CDMA communications is the rake receiver. In this paper, the downlink performance is estimated for a CDMA mobile system at the vertex of multiple adjacent cells. At the base station the received signal is coherently dispread and demodulated using a rake receiver. The effects of power control, error correction and rake receiver were also investigated on the assumption that the received signals undergo Rayleigh fading, lognormal shadowing, and frequency selective fading. The evaluation of performance measures of base to mobile link (downlink) of a multiple-cell CDMA mobile system is presented. This study demonstrates that significant performance improvements are achievable with combined use of power control, rake receiver and error correction scheme.

关键词： DS-CDMA Power Control rake Receiver Error Correction Probability Density Function

Uplink Performance Evaluation of CDMA Communication System with rake Receiver and Multiple Access Interference Cancellation

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International Journal of Communications, Network and System Sciences 2010年第6期3卷 540-547页

作者： Ayodeji J. Bamisaye Michael O. Kolawole 不详

In CDMA communication systems, all the subscribers share the common channel. The limitation factor on the system’s capacity is not the bandwidth, but multiuser interference and the near far problem. This paper models CDMA system from the perspective of mobile radio channels corrupted by additive white noise generated by multipath and multiple access interferences. The system’s receiver is assisted using different combining diversity techniques. Performance analysis of the system with these detection techniques is presented. The paper demonstrates that combining diversity techniques in the system’s receivers markedly improve the performance of CDMA systems.

关键词： CDMA Multipath Diversity Multiple Access Interference Cancellation rake Receiver Parallel Interference Cancellation

直扩超宽带系统在室内密集多径下的多址性能(英文)

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Journal of Southeast University(English Edition) 2005年第4期21卷 393-397页

作者：樊祥宁倪剑强毕光国东南大学移动通信国家重点实验室南京210096

分析了脉冲方式直扩二相相移键控超宽带无线通信系统在室内多用户和密集多径环境下用户码对系统性能的影响,推导了采用rake接收时系统的输出信号,并为直扩超宽带系统提供了一种简单而切实可行的用户码方案,即:在大的脉冲波形占空比的条... 详细信息

分析了脉冲方式直扩二相相移键控超宽带无线通信系统在室内多用户和密集多径环境下用户码对系统性能的影响,推导了采用rake接收时系统的输出信号,并为直扩超宽带系统提供了一种简单而切实可行的用户码方案,即:在大的脉冲波形占空比的条件下,直接选用码长足够长的、具有良好的互相关正交特性的随机或伪随机用户码即能使脉冲方式直扩超宽带无线系统获得接近最佳的性能,从而不必精心设计和选择用户码.仿真了rake接收时CM1～CM4多径信道下采用Gold序列与随机二进制PN序列作为用户码时的多用户性能,验证了提出的用户码方案的可行性.

关键词：超宽带多用户多径 Gold码直接序列 rake