Table of Content

20 January 2007, Volume 43 Issue 1

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Using UML for Specification and Refinement of Software Architectures

SUN Meng,YANG Hongli,ZHANG Naixiao,QIU Zongyan

2007, 43(1):  1-10. 

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Different views of software architecture in UML diagrams are presented. It shows how UML can be used to model different aspects of software architecture. The semantics of UML diagrams are expressed in the notation of Communication Sequential Process(CSP). Different view models of software architectures are linked together based on the CSP semantics. The issue of refining such architectural specifications is also discussed, where software architectures can be refined in a manner that preserves desired system properties.

Nonlinear Prediction of ENSO

LI Kunyu,LI Xiaodong

2007, 43(1):  30-35. 

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Nonlinear time-sequence analysis is used to study the time evolution of El Nino-Southern Oscillation (ENSO) by combining the method of global function approximation with lyapunov exponent analysis. The method includes phase-space reconstruction, lyapunov exponent analysis, global function approximation, principal components analysis and least-square estimation. The data used here is monthly sea surface temperature anomalies (SSTA) from CZ (Cane & Zebiak) model. It differs from traditional time-sequence analysis methods in which nonlinear chaotic time-sequence prediction is used. The present method is proved to be a successful one with lesser data, and it provides an alternative method for ENSO prediction.

Design of a 3.1-10.6GHz Ultra Wideband Low Noise Amplifier

SONG Ruifeng,LIAO Huailin,HUANG Ru,WANG Yangyuan

2007, 43(1):  78-81. 

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A 3.1-10.6GHz ultra wideband LNA was designed using standard 0.35μm SiGe HBT process. The simulation result shows that, with careful selection of circuits structure and device parameters, it is possible to fabricate a UWB LNA using standard 0.35μm SiGe HBT process. In the designed band, the S11and S22 of the designed LNA is better than -8dB, and the S21 is about 11dB with supply voltage of 2.5V and draws a current of 4.38mA, and the noise figure of the LNA is 3.5dB.

Theoretical Solution of Casing Loads in Rheological Formation in Tectonic Stress Field

LI Pingven,YIN Youquan,SU Xianyue

2007, 43(1):  11-16. 

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Based on the elasticity viscoelasticity correspondence theory and the acquired elastic solution, assuming the formation obey the Kelvin viscoelastic constitutive relation, the theoretical solution of casing loads in rheological formation in tectonic field and the analytic expression of relaxation time are obtained. The results indicate that the casing load in tectonic field changes with time and it exists a critical time in which the casing load has the most value. The viscoelastic solution is coincidence with corresponding elastic solution when the time is long enough. The casing tectonic stress load defined by elastic solution is slightly less than the maximum pressure subjected by casing pipe in rheological formation. Therefore, the elastic computation load or safety coefficient should be increased properly in design to ensure the safety of the casing pipe.

Vortex Dynamics on Synoptic Maps

LIU Gang,LIU Shida,LIU Feng,LIU Shikuo

2007, 43(1):  17-22. 

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There are many vortex patterns on synoptic maps. It is shown from this thesis that flow fields on synoptic maps can be decomposed into rotation and deformation fields. Geostrophic non-frictional cyclone and anticyclone vortex patterns are closed circulations around the center point, streamlines of frictional cyclone and anticyclone patterns have spiral forms around the focus point. Saddle fields have four vortex centers (two cyclones and two anticyclones) and a saddle point. Blocking high pressure and cut-off low pressure patterns consist of a vortex center and a saddle point. From the above results, we can clearly understand the actual atmospheric vortex dynamics and its mechanisms of formation.

A Comprehensive Analysis of 721 Low-Level Wind Shear Weather Process at Guangzhou Baiyun Airport

LIU Feng,LIU Shida,WEN Danqing

2007, 43(1):  23-29. 

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Wind shear incidences are always related to local downburst, gust front or other systems. An analysis of a low-level wind shear case at Guangzhou Baiyun airport on Jul 21, 2005 shows that this case was caused by downburst and gust front. The real-time wind data from local terminal Doppler radar and auto weather observation stations were calculated to obtain the degree of wind shear and turbulence. Flight data belong to one aircraft has verified the method to alert wind shear is feasible under the limited resources of Guangzhou Baiyun airport.

Characteristics of Temperature and Humidity Profiles in the Boundary-Layer over Baiyangdian Wet Land in Late Summer Season

LIU Xinjian,ZHANG Hongsheng,SONG Xingzhuo,KANG Ling,CHEN Jiayi,LI Aiguo,HU Fei

2007, 43(1):  36-41. 

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An experiment on heterogeneous underlying surface was conducted by Peking University and the Institute of Atmospheric Physics, Chinese Academy of Science (CAS), in Baiyangdian in September of 2005. High-precision humidity and temperature measurements were made at two different sites with underlying surfaces of land and water, respectively. Profiles of temperature and humidity were also studied. The results indicate that the structures of the atmospheric boundary layer (ABL) over Baiyangdian Wetland are different from that in other places, such as humidity and temperature inversion appears frequent. It is found that the ABL over the land surface has a lower temperature, shallower ABL depth, but higher humidity, compared with that over the lake site. The possible factors are the prevailing winds, energy budget and land-air interaction. This experiment also provide an opportunity to test the quality of humidity sensor and temperature sensor designed by Peking University.

Simulation of Wind, Temperature and Humidity Fields over Beijing Area in Summer Using an Improved Model

LIU Shuhua,ZHOU Bin

2007, 43(1):  42-47. 

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The meso-scale urban atmospheric boundary layer model of Peking University, with three-dimensional complex topography, was improved by introducing the second generation land-surface model, which paid more attention to the effect of vegetable coverage when computing land-surface water balance. The improved model was used to simulate temperature, wind and humidity fields over Beijing in summer. It is found that the model can provide acceptable results compared with observations. The simulation results are important to understand the local climate over Beijing area and the feature of diffusion of pollutants, and are helpful for making practical urban design.

Routability Analysis Model for Mixed-Signal Integrated Circuits

LI Zhenrong,LIU Xiaoyan,ZHANG Xisheng

2007, 43(1):  61-66. 

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Placement and routing are two main parts of the physical design in IC design flow. To optimize the placement and improve the performance of routing, early routability analysis during the placement is indispensable. In this paper, a new non-slicing irregular partition algorithm is proposed. And based on it, a routability analysis model for mix-signal integrated circuits is introduced. Two experiments prove the high efficiency and accuracy of this routability analysis method.

Novel Low Power Column Stage Design of 302×288 Infrared ROIC

LIU Dan,LU Wengao,CHEN Zhongjian,JI Lijiu,ZHAO Baoying

2007, 43(1):  67-71. 

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A novel readout architecture for infrared (IR) readout integrated circuit (ROIC) is proposed. When the readout rate is 5MHz, the power of the column readout stage has been reduced from more than 47mW to 6.74mW, by applying master-slave column amplifier and the technology of divided-output-bus, which reduced more than 80%. In the master-slave readout structure, master amplifiers convert the charge to voltage, which has relaxed time limit. Slave amplifiers drive the output bus and ensure the readout rate, which adopts low power standby work mode. The technology of divided-output-bus is to divide the 320 pairs of switches to 20 groups and to reduce the switches connected to the output bus, which does help to reduce power dissipation of slave amplifiers.

Research on Multi-Granularity Optical Cross-Connect

ZHANG Yu,XU Anshi,WU Deming

2007, 43(1):  72-77. 

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Adopting multi-granularity switching in WDM optical networks can dramatically reduce the size of optical cross-connect, which saves the cost of building and maintaining of networks. In this paper, the structures of multi-granularity optical cross-connect in some previous works are introduced, and two kinds structure of multi-granularity optical cross-connect are proposed. The performances of different structures are analyzed and compared in terms of size of switching box, switching and grooming abilities, and the blocking performance.

A Novel Classification Method—AMC-ASVM

SUN Xichen,HE Renya,FENG Jufu

2007, 43(1):  82-84. 

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A novel pattern classification method, named AMC-ASVM, was proposed based on Attribute Mean Clustering and Support Vector Machine. The advantages of AMC-ASVM include robustness and high efficiency. AMC ASVM is the natural extension of Cluster Nearest Neighbor Classification as well. Application in Microarray Analysis shows the performance of the present method.

Characterizing the d-TLB Behavior of Typical Applications on Network Computer

QU Ning,YUAN Peng,GUAN Xuetao,CHENG Xu

2007, 43(1):  85-91. 

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Network computer is an interactive device in thin-client computing environment, and studying the behavior of typical applications on this platform is important to the microprocessor design and system development. Based on PKUnity network computer platform, this paper analyzes the d-TLB miss rate and performance penalty of many typical applications under different d-TLB structures and page sizes. The experiment results explain the advantage of TLB design in PKUnity SoC which satisfies the requirement of lower power and low complexity.

A High Efficient Method to Generate the Verification Vector of ICs

SUN Zhao,WANG Yong

2007, 43(1):  92-95. 

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Verification is very important in designing digital systems. It has become a bottleneck in the modern digital system design cycle. In an effort to improve current verification method based on simulation, this paper presents a method for the generation of simulation vectors using FSM. It can improve the coverage of the state space.

PN Based Channel Estimation in SC-FDE System

JIAO Xianjun,ZHANG Lei,XIANG Haige

2007, 43(1):  103-108. 

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A PN (Pseudo Noise) based Channel Estimation (CE) algorithm using circular correlation is proposed, and is implemented in Single Carrier Frequency Domain Equalization (SC-FDE) system. The new CE algorithm is compared to typical frequency-domain algorithms, and it is found that new algorithm has lowest complexity and acceptable performance. A no-guard-interval PNA-SC-FDE (PN Assisted SC-FDE) system is studied and a simpler receiving procedure for interference-canceling based receiver is proposed. Simulation shows that the performance of receiver with interference-canceling and new CE algorithm can approach the performance of receiver with perfect CSI (Channel State Information).

A Generic Programmable Dual Modulus Divider

HUANG Shuilong,WANG Zhihua

2007, 43(1):  109-112. 

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A programmable dual modulus divider is proposed. The circuit mainly includes three building blocks: prescaler, 8-bit programmable counter and ΣΔ modulator. Two operation modes (integer/fractional-N) are achieved by switching on/off the output signal of the ΣΔ modulator. Only a programmable counter is needed for the swallow pulse divider. The prescaler was designed by using the improved dynamic TSPC triggers, and the other blocks were realized by the way of digital synthesis, placing and routing. Based on 0.18μm 1.8V CMOS technology, SpectreVerilog simulations verify that it can operate within the division ratio of 56-2 047 with 2GHz maximum operation frequency and <4mA current dissipation. The circuit is very simple and can be used in the high performance PLL frequency synthesizer.

IFOG: An Indexed-Cache Framework over Data-Grids

ZHANG Junhu,YANG Dongqing,TANG Shiwei

2007, 43(1):  96-102. 

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The problems on the rapid replica location and consistent replica access on a data-grid were studied. By analyzing the associated issues on replica caching, cached replica tracing and replica adjacency perceiving in data-grids, the paper proposes a distributed "Indexed-Cache Framework Over Data-Grids" (IFOG) and accomplishes an algorithm of the rapid replica allocation and access. The experiment shows that IFOG is good at rapid allocation of near replicas, which greatly improves the efficiency of the Replica Location Service (RLS) on data-grids. The consistent replica access algorithm over IFOG can provide better replica access speed for data-grid applications without increasing the price of replica consistency maintenance.

Enhanced Modeling of Multi-Access Interference and BER Derivation for TH-PPM UWB System

WU Jianjun,CHEN Jiang,JIANG Wei,XIANG Haige

2007, 43(1):  113-118. 

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The Time-Hopping Pulse Position Modulation (TH-PPM) is one of the most popular approaches for IR-UWB multi-user systems, and a lot of research efforts have been devoted on its performance analysis. In several latest literature, a method of numerical computation of MAI characteristic function was carried out to derive precision analytical error performance, which, however, still showed a few inconvenient limitation on the system configuration. To overcome this shortage, the corresponding MAI model is enhanced in this paper, and the multi-access BER performance expression is also derived based on this modified model. Finally, Monte-Carlo simulations are carried out to verify the analytical results.

The Research of FEM PML Method with Mixed Order Hierarchical Vector Base Functions for 3D Radiation Problems

NIAN Feng,DONG Shuo,ZHOU Lezhu,XIA Mingyao

2007, 43(1):  119-124. 

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An effective vector finite element method (FEM) for analysis of 3D radiation problem is proposed. This method combines the perfect matching layer (PML) and mixed order hierarchical vector base functions in which different order base functions are adopted in different regions according to the intensity of field distribution in the whole calculating domain. Without loss of accuracy, the efficiency of FEM+PML method can be increased greatly by the reduction of the number of unknowns and computational time compared with a pure higher order method. Correctness and effectiveness of the proposed method are demonstrated through numerical experiments.

Experiments on the IVAP Single-Doppler Radar Wind Retrieval Method

MEI Jue,LIANG Xudong,Lv Huanyu

2007, 43(1):  48-54. 

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The single-Doppler radar wind retrieval method is useful to enhance the applications of the Doppler radar in the observing and forecasting of mesoscale weather system. This paper shows that the VAD and VAP methods can be derived from the same relationship based on the azimuthal uniform wind assumption. By using this assumption, an IVAP (Integrating VAP) method is developed, which can overcome the sensitivity of VAP method to the short wave and too smooth property of VAD method in Doppler velocity. By using the IVAP technique, the wind fields associated with a heavy rainfall case in Shanghai (Aug. 5^th, 2001) are retrieved using a Doppler radar located at the Hongqiao Airport. Retrieved winds using azimuthal sector length of 9°,18°,45°, and 90° indicate that using shorter sector length can exhibit the cyclonic stream and mesoscale convergence line related to the heavy rainfall. The quality of the retrieved winds is validated by using surface observations and wind-profiler data. Comparison of the radar retrieved winds with surface observed winds indicates that retrieved winds have good correlation with surface observations. The larger the sector length the higher is the correlation coefficient. Twenty wind-profiler data at the same height and time also have good correlation with Doppler radar retrieved winds. The square mean errors ofu or v are about 2m·s^-1. All of the results indicate that the IVAP method is more objective to be used in applications of Doppler radar.

An Efficient Algorithm Based on Covering Codes about Ranking the Results of Partial-Sum Queries

ZHANG Weihua,TAN Shaohua,YIN Pujie,ZHANG Yuyu,CHENG Fu

2007, 43(1):  55-60. 

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In decision-support systems, ranking-aware queries have been gaining much attention recently. An efficient algorithm is introduced, which, by incorporating covering codes and pre-sorting, can effectively resolve the top-k queries over partial-sum results. This algorithm is empirically evaluated and the experimental results show that the query cost is improved significantly.

Synthesis and Characterization of Sodium Titanate Nanowires

ZHANG Yue,CHEN Qing,GONG Weiwei,HE Meng

2007, 43(1):  125-131. 

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Titanate nanowires with layered structure were synthesized through hydrothermal reaction between TiO₂ powder and NaOH aqueous solution at the temperature 175℃-240℃. Influence of experimental parameters, such as molar ratio of reagents NaOH/TiO₂ and reaction temperature were studied. The structure of the nanowires was studied using X-ray diffraction, electron microscopy and energy-dispersive X-ray spectroscopy. There were a lot domain boundaries and defects observed in the nanowires. The structure of the nanowires was found not to be the same with any known structure. The structure can be indexed using a monoclinic unit cell with a=2.15nm, b=0.377nm, c=1.28nm, β=103.5°. Moreover, K₂Ti₈O₁₇ nanowires were fabricated through hydrothermal reaction between the synthesized sodium titanate and KOH aqueous solution.

A Novel Unicast Based Multiplexing Scheme to Improve the Capacity of VoWLAN

WANG Dong,LIU Zhimin,ZHAO Yuping,LUO Yan,LI Honggang,LE Jilin,CAO Yang

2007, 43(1):  132-137. 

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The mergence of VoIP and WLAN created a new wireless platform for voice service delivery, VoWLAN. This paper figured out the capacity bottleneck of VoWLAN, and analyzed the problems in current solutions such as M-M. A novel unicast based multiplexing scheme (U-M, Unicast Multiplexing) to improve the capacity and performance of VoWLAN was proposed. Both theoretical and simulation results showed that this scheme improved the voice capacity to nearly 100% comparing to the traditional un-multiplexed scheme, and reduced the packet lost ratio by 10% compared with the M-M scheme. Meanwhile, the U-M scheme is a power-saving scheme in the voice-oriented application as well. Therefore the proposed U-M scheme is an effective solution to increase the voice capacity of WLAN and improve the performance of VoIP service.

A Dual Field Modular Inversion Algorithm and Hardware Implementation

WANG Jian,JIANG Anping,SHENG Shimin

2007, 43(1):  138-143. 

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The finite field arithmetic is the base of cryptography and modular inversion is the kernel arithmetic operation. The authors present a dual field modular inversion algorithm. The 256-bit inversion circuit based on the proposed algorithm can be used at the 167MHz clock frequency. It also has an improvement in area complexity compared with other designs.