FPGA implementation of adaptive code rate QC-LDPC encoder

准循环低密度奇偶校验码(QC-LDPC codes)相比其他的LDPC码具有简单的编码结构,拥有较好的应用前景。通过构造校验矩阵设计了不同码率和不同帧长的具有系统结构的QC-LDPC码,并分析了这些码的性能,随后将编码过程分阶段引入主从控制模块及复用基本SRAA组,设计了变码率和变帧长的编码器,并用Verilog HDL语言在Spartan 3 3s1500fg676芯片上实现了编码器的设计。综合报告表明:在使用适中的硬件资源情况下,系统最大频率达到了174.856 MHz,能满足高速编码的要求。Quasi-cyclic(QC) low-density parity-check(LDPC) codes have encoding advantage over other types of LDPC codes for their simple coding structure.Different rates and frames QC-LDPC codes in systematic-circulant(SC) form were designed by constructing the parity check matrix,and their performance was analyzed.The design introduced two control-modules and reused SRAA circuits to realize multi-rate encoding.The encoder was implemented with Verilog HDL language on the chip of Spartan 3 3s1500fg676.Synthesis report shows that the system's max frequency is 174.856 MHz with mezzo hardware device and satisfies the demand of high rate-encoding application.教育部新世纪优秀人才支持计划项目(NCET04-0601);; 福建省科技重点项目(2006H0039);; 重庆市自然科学基金项目(CSTC2007BB2387

The spatial-temporal distribution of Namalycastis abiuma in the Futian mangrove wetland of Shenzhen Bay as well as its relationship to climate response

根据2004年1月至2007年12月在深圳湾福田红树林湿地3条断面10个取样站进行大型底栖动物14个季度监测获得的溪沙蚕[nAMAlyCASTIS AbIuMA(MllEr)]密度和生物量数据,阐述了溪沙蚕数量的年际变化、季节变化和空间分布,分析了溪沙蚕栖息密度、生物量与部分环境因子的关系。结果表明,深圳湾福田红树林湿地溪沙蚕密度和生物量的年均值大小顺序均是:2005年>2006年>2007年>2004年。溪沙蚕密度的季节均值大小顺序是:夏季>春季>冬季>秋季;而溪沙蚕生物量的季节均值大小顺序是:春季>夏季>冬季>秋季。深圳湾福田红树林湿地溪沙蚕的空间分布很不均匀,不同断面或取样站之间数量差别很大,有红树林的取样站溪沙蚕密度高,没有红树林的取样站溪沙蚕密度很低。相关分析表明,溪沙蚕密度和生物量与沉积物中的总有机质、中值粒径、硫化物等参数没有显著相关关系。溪沙蚕2004年的年平均密度和生物量为最低值,2005年到2007年逐年下降,与降雨量的减少趋势是一致的,但溪沙蚕的密度、生物量与降雨量、气温、光照时数、相对湿度均没有显著相关。可见,红树林湿地是溪沙蚕喜好栖息的生境,溪沙蚕对降雨量等气候因子的响应不显著。The seasonal and annual population dynamics of Namalycastis abiuma,as well as its spatial distribution,were studied in the Futian mangrove wetland of Shenzhen Bay from January 2004 to December 2007.The monitoring of density and biomass took place at ten sampling stations of three transects.The relationship between N.abiuma quantity and environmental factors was analyzed.The highest annual averages of both density and biomass of N.abiuma in the wetland were recorded in 2005,the second in 2006 and the third in 2007.The lowest annual average occurred in 2004.The highest seasonal average of the distribution density of N.abiuma was in summer and the lowest in autumn,while the highest biomass was in spring and the lowest in autumn.The spatial distribution of N.abiuma was uneven.High density of N.abiuma was found in the mangrove area and low density was found in the non-mangrove area.There was no obvious relationship between the density and biomass of N.abiuma and environmental factors,such as total organic matter,grain size,sulfide abundance,and other factors in the sediment.The lowest annual average of rainfall was in 2004 and decreased annually from 2005 to 2007,which coincided with the annual changes of both density and biomass of N.abiuma.However,there was no direct relationship between the density and biomass of N.abiuma and other environmental factors,such as rainfall,air temperature,illumination time,and relative humidity.In conclusion,N.abiuma preferred the mangrove wetland habitat compared to the non-mangrove area and its response to rainfall and other climate factors mentioned above was not significant.中国科技部资助项目(2006FY-220700);广东内伶仃福田国家级自然保护区管理局资助项

Research and implementation of OPC UA Publish /Subscribe mode based on message broker

针对目前OPC UA客户端/服务器通信模式中存在的紧耦合、服务器性能瓶颈等问题,进行了OPC UA发布/订阅通信模式总体架构的研究。首先具体分析了UA的核心功能,包括地址空间技术和数据编码技术,并在两者的基础上,利用消息代理机制,完成了发布者和订阅者的功能开发。还通过实验进一步验证了功能的稳定性和对数据的传输能力,结果表明,此模式可以满足大多数工业需求。</p

新疆头屯河流域山地侵蚀与减沙治理研究

该项目以天山山区为背景，头屯河流域为研究对象，详尽研究了干旱区流域山地侵蚀过程、流域产输沙特性、水库排沙减淤以及流域减少综合治理的方案和技术措施。采有半定位实验观测方法，获取流域不同坡向、不同土壤、不同植被条件下的土壤抗蚀性和水土侵蚀过程等定量数据，并进行河床不同粒径物质起动条件、运动规迹的观测试验，运用微机技术和系统动力学方法，进行流域产输沙计算和河流水沙匹配分析，建立河床冲刷演变、河流产输沙机理、土壤侵蚀计算模型，应用地理信息系统（ＧＩＳ）模拟流域产输沙过程，计算不同地带的水土侵蚀强度，并进行流域产沙区划分，提出了抑制水土流失，削弱山地侵蚀和河流来沙量的工程、生物及社会措施，分析和确立了头屯河水库冲刷恢复库容和兼顾防洪兴利的水库运用方式，并结合头屯河实际情况，加以实施应用，收到了良好效果，可推广应用于干旱区中、小流域治理和水土保持工作