一种基于三维整型DCT变换的高光谱图像无损压缩方法

本文根据高光谱图像具有空间和谱间相关性的特点,提出一种基于三维整型DCT变换的无损压缩方法.首先采用三维整型DCT变换消除高光谱图像空间和谱间的相关性;然后,对变换系数进行类似小波的树状系数重组,并按子带顺序进行一阶自适应算术编码.实验结果表明,本文提出的方法与JPEG2000中无损压缩算法相比,平均比特率降低0.1～0.4bpp;与JPEG-LS相比,平均比特率降低0.01～0.2bpp.     

MPEG-2 AAC解码器的优化算法

作为新一代的音频编码国际标准,先进音频编码(AAC)提供了良好的压缩性能,具有广阔的发展和应用前景。但是由于AAC标准给出的算法比较复杂,按照标准算法进行测试时发现其并不能满足实时解码的要求,因此,必须对标准算法进行优化以达到实时解码的要求。在叙述了MPEG-2 AAC解码器的模块组成和原理的基础上,针对各个模块的特点采用优化算法,对MPEG-2 AAC解码器的部分模块进行了优化设计,较大程度地提高了解码速度。     

基于微处理器核的AAC解码软硬件协同优化

为了降低硬件成本和在较低频率下实现基于精简指令集计算机（reduced instruction set computer, RISC）处理器的先进音频编码（advanced audio coding，AAC），提出了一种软硬件协同优化策略，通过对解码关键子模块进行分析，从比特流解码、解码运算部分、播放控制3个方面来实现软件算法的优化，从而加快音频解码速度，减少存储空间，并根据优化结果对嵌入式RISC微处理器核进行配置.在现场可编程门阵列（field programmable gate array, FPGA）验证平台上实现了对128 kbps，44.1 kHz双声道AAC 低复杂度框架（low complexity profile, LC）的实时解码，运算量为25.51 MIPS，优化率为48.9%.     

基于微处理器核的媒体系统芯片结构设计

围绕基于微处理器核的AAC解码器结构设计展开讨论，对IP定制、数据通路及存储设计进行了研究，并成功开发了一个基于微处理器核的MPEG-4AAC解码系统芯片。     

MP3／AAC解码器中Huffman硬件加速器设计与实现

Huffman解码是感知音频解码过程的重要部分。软件实现Huffman解码运算,计算速度慢、功耗高,采用硬件实现的方法,设计并实现了一个兼容MP3与AAC标准的Huffman解码硬件加速器。采用十六叉树搜索算法．在存储空间增加不大的情况下,有效减少了Huffman码字的搜索深度,简化寻址操作,加快了搜索速度。通过直接外设访问的接口设计,该硬件加速器还可快速进行音频码流的数据读取。在XilinixFPGA上的功能和性能验证表明。该Huffman硬件加速器可成功应用于MP3和AAC解码器。     

MPEG-4 AAC解码器在NIOS Ⅱ平台上的实现和优化

给出了MEPG-4AAC实时解码器在NIOSⅡ平台的实现方案，介绍了MPEG-4AAC—LC解码算法及各关键模块优化算法。在完成实时解码要求下，结合NIOSⅡ平台特性，对解码器在软件代码与处理器上进行优化。实验结果表明CPU时钟为80MHz时能达到实时解码要求。     

蒸压砂加气混凝土砌块在节能建筑工程中的应用

蒸压砂加气混凝土砌块具有轻质、防火、保温、隔热、隔音、抗震、绿色环保等优越性能,可作为国家实现建筑物“三步节能”单一材料达标的一种产品,干作业、施工快、工期短,可降低工程成本,在建筑外墙外保温工程中采用时无需再做其他保温材料.     

基于MPEG-AAC编码器的压缩域音频增强方法

本文基于MPEG-AAC音频编解码器,提出了一种压缩域的音频增强方法.首先,对含噪音频信号的比特流进行解码,得到含噪音频信号的MDCT系数;然后,利用修正的加权递归平均（Modified Weighted Recursive Averaging,MWRA）方法估计噪声功率;再者,利用基于听觉掩蔽原理的自适应β-阶双曲余弦（COSH）统计模型,对含噪音频的MDCT系数进行增强处理;最后,将增强后的MDCT系数重新量化编码,得到用于解码的增强比特流实验结果表明,本文提出的方法能有效去除AAC解码音频信号中的多种背景噪声,其性能明显优于参考方法.     

Breeding strategies for improving the performance and fruit quality of the pepino (Solanum muricatum): A model for the enhancement of underutilized exotic fruits

The pepino (Solanum muricatum Aiton) is a neglected Andean crop that has elicited an increasing interest from exotic fruit markets. The pepino is highly diverse and, by using appropriate breeding strategies, it has been possible to develop new improved materials. Here we review more than a decade of efforts and advancements made in the genetic improvement of the pepino for several traits, with special emphasis on fruit quality. Different strategies, like the use of a wide diversity of genetic resources, exploitation of genotype × environment interaction, use of clonal hybrids, and introgression of genes from wild species, have facilitated significant developments in enhancing the commercial potential of the pepino, and have allowed the development of new cultivars and breeding materials adapted to new agroclimatic conditions. Agronomic performance of the pepino has been improved by the use of genetic parthenocarpy, selection for resistance to Tomato Mosaic Virus, and by developing hybrids, that manifested heterosis, but also did not have lower quality fruit. Breeding for quality has been focused mostly on the improvement of flavor (sweetness and aroma) and nutritional value (ascorbic acid content; AAC). Despite the limited intraspecific diversity available for sugar content, materials with high soluble solids content (SSC) have been selected. Strategies for further increases of SSC and titratable acidity have been based in the use of wild relatives. The study of variation within the cultigen was also helpful in the selection of hybrid genotypes with improved aroma profiles and high AAC values. As a result of the breeding efforts, several cultivars with improved agronomic performance and fruit quality have been produced. The use of biotechnological tools represents an opportunity to use the extensive genomic information compiled for related species, like tomato or potato, for the future improvement and enhancement of pepino quality. The results obtained in the pepino show that ample opportunities exist for improving the commercial potential of under-utilized fruits by means of breeding based on the exploitation of genetic diversity.     

MPEG-4 AAC实时编解码系统研究

介绍了音频编码的一般原理和常用的音频压缩方法,并简要论述了AAC编解码过程中要用到的感觉模型、TDAC技术和Huffman编解码。