基于∑-△调制技术的信号发生器设计

提出了一种新的采用∑-△调制和无损离散积分振荡器来产生片内模拟信号的方法.研究了电路的实现原理和噪声传递函数零点优化设计方法,运用无乘法器的梯型滤波器结构和∑-△调制技术避免了多位高精度乘法运算和多位D/A数模转换器硬件成本高的缺点.除一个比较器外,整个电路全部由标准CMOS工艺来实现集成,硬件成本非常低,非常适用基于可测性混合集成电路的设计.通过一个6阶实例和仿真的结果表示:6阶的信号发生器具有120 dB衰减的动态带宽.     

一种新型级联ΣΔ调制器系统结构

针对传统高阶级联ΣΔ调制器结构电路复杂和对运算放大器的增益和线性度要求较高的缺点,提出了一种新型的2-3两级5阶多位量化器级联ΣΔ调制器系统结构.该结构的第1级采用2阶多位量化器的低失真ΣΔ调制器结构,减小了运算放大器的非线性有限增益对调制器性能的影响.第2级采用信号传递函数等于单位增益的单环3阶ΣΔ调制器,而不是传统级联结构中1阶或2阶ΣΔ调制器,降低了电路的复杂程度.系统仿真结果表明：在最大增益为70 dB的非线性运算放大器增益、±0.2%的随机数模转换误差的非理想条件下,该调制器的最大信号噪声失真比能够达到95 dB.     

FPGA数据扩展方式的ΣΔ调制器设计

文中针对模拟电路实现ΣΔ调制对输入信号幅度存在限制的问题,设计实现了基于FPGA数据扩展方式的二阶ΣΔ调制器。该调制器能够对满幅信号进行正确调制,且输出波形可通过简单的无源滤波器实现量化噪声的滤除及信号的解调。相对于模拟电路,FPGA实现通过内部寄存器数据位的有效扩展,防止中间过程数据溢出造成的调制错误,保证电路的稳定性。相应结论均通过仿真模拟及硬件实现证明。     

基于ΣΔ调制的频率合成器及其性能

ΣΔ模数变换器使用内部１位量化器就能提供较高分辨率的输出。将ΣΔ调制技术应用于频率合成器中，能较好地提高频率合成器的频率覆盖范围、相位噪声及频率分辨率。定量地分析了ΣΔ调制频率合成器的性能，给出了实现方法。     

一种4 M-Pixel/s 4通道X射线CCD读出电路

本文设计了一种4 M-pixel/s 4通道X射线CCD读出电路.为加快读出速度,采用相同的4个通道并行处理CCD信号,每通道由2个3阶3位增量型ΣΔ模数转换器(I-ΣΔADC)交替采样CCD信号进行量化.在调制器结构中引入环路延时迁移(SLD)缓解紧张的时序.设计实例采用0.35μm 2P4M CMOS工艺实现,芯片工作在3.3V电源电压和64MHz时钟频率下,设计获得前端电路折算到输入的等效积分噪声为13.53μV,积分非线性为0.009 6%,功耗为1.35W.     

一种通用的可编程双模分频器

提出了一种通用的可编程双模分频器,电路主要由3部分组成:9/8预分频器,8位可编程计数器和ΣΔ调制器构成。通过打开或者关断ΣΔ调制器的输出来实现分数和整数分频两种工作模式,仅用一个可编程计数器实现吞脉冲分频器的功能。9/8预分频器采用提高的TSPC动态触发器实现,而可编程分频器和调制器采用数字综合后布局布线的方法实现。基于SMIC0.18μm1.8V电源CMOS工艺的SpectreVerilog仿真表明:它能在分频比56-2047范围内工作,最大工作频率大于2GHz,消耗的电流小于4mA,适合应用在高性能的频率综合器中。     

基于FPGA的SD转换器的设计与实现

文章提出了一种采用Altera公司的Cyclone系列EP1C6F256C8FPGA芯片设计SD转换器的硬件电路的方法,并以一个加海明窗的160阶Fir低通数字滤波器进行数字信号处理,设计经软件仿真和硬件仿真,结果表明电路性能可靠,SD转换精度较高。     

声呐发射机驱动信号调制性能的研究

PWM(pulse width modulation)调制和ΣΔ调制方式均能将任意波形信号转化为一位比特流信号,可以作为声呐发射机的驱动信号。为对比研究这2种调制方式在声呐发射机驱动信号调制应用方面的性能,文中将理论分析通过仿真结果,从5种衡量声呐发射机驱动信号调制性能的指标着手做出评价。通过对比得出结论,在声呐发射机应用方面,两者具有相同的电效率,但ΣΔ调制具有更高的输出线性度和更小的谐波失真度。     

基于振弦式传感器的测频系统设计研究

为确保监测振弦式传感器数据采集的准确性,提出了一种用多周期测频的方法,来实现振弦式传感器频率的测量.同时设计出了具体的硬件电路,系统硬件分为3个模块单元:温度补偿电路、测振电路、激振电路、应用AT89C52单片机来达到对多周期测频方案的实现、实用电路,该电路具有的特点为:测频范围宽和测量精度高等,并且应用AT89C52...     

一个新混沌系统的电路设计与实现

根据电路设计原理,设计了一种新颖电路来实现一个新的混沌系统,整个电路由加减运算电路、积分电路、反相电路3部分组成,电路结构对称.基于硬件电路实验平台,对设计的电路进行硬件电路实验研究,给出相应的实验结果,硬件电路实验结果与计算机仿真结果完全一致.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.