T-DMB标准视音频编码容错技术研究

从视音频编码角度出发,对提高T-DMB系统视音频播放质量的一些客错技术进行了总结归纳.介绍了T-DMB标准视音频编码的基本原理,讨论了T-DMB系统固有的客错特性,对基于解码端客错工具的错误隐藏技术进行了总结.     

MPEG-4 AAC心理声学模型在TMS320C6416上的实现

心理声学模型是MPEG-4 AAC音频编码器中最重要的部分之一.本文首先介绍了心理声学模型的作用,基本原理和算法流程,然后结合定点DSP芯片TMS320C6416的特点,详细说明了心理声学模型模块的定点化方法及其优化设计方法.测试结果表明,在保证音频编码质量的前提下,算法的精度和运行速度都得到了很大的提高.     

Folding and Biogenesis of Mitochondrial Small Tim Proteins

Correct and timely folding is critical to the function of all proteins. The importance of this is illustrated in the biogenesis of the mitochondrial intermembrane space (IMS) “small Tim” proteins. Biogenesis of the small Tim proteins is regulated by dedicated systems or pathways, beginning with synthesis in the cytosol and ending with assembly of individually folded proteins into functional complexes in the mitochondrial IMS. The process is mostly centered on regulating the redox states of the conserved cysteine residues: oxidative folding is crucial for protein function in the IMS, but oxidized (disulfide bonded) proteins cannot be imported into mitochondria. How the redox-sensitive small Tim precursor proteins are maintained in a reduced, import-competent form in the cytosol is not well understood. Recent studies suggest that zinc and the cytosolic thioredoxin system play a role in the biogenesis of these proteins. In the IMS, the mitochondrial import and assembly (MIA) pathway catalyzes both import into the IMS and oxidative folding of the small Tim proteins. Finally, assembly of the small Tim complexes is a multistep process driven by electrostatic and hydrophobic interactions; however, the chaperone function of the complex might require destabilization of these interactions to accommodate the substrate. Here, we review how folding of the small Tim proteins is regulated during their biogenesis, from maintenance of the unfolded precursors in the cytosol, to their import, oxidative folding, complex assembly and function in the IMS.     

DAB+音频解码器中TNS模块优化设计及硬件实现

时域噪声整形技术被广泛地应用于各种感知音频编解码方案中,能有效地消除由量化噪声所产生的预回声现象。由于数字音频广播音频解码器(HE-AAC v2)算法复杂、运算量大,目前多采用DSP或嵌入式软件方式实现,本设计基于数字音频广播音频解码纯硬件系统,通过对时域噪声整形(TNS)解码算法的优化,以极低的硬件代价完成了时域噪声整形全硬件解码模块设计,具有高硬件资源利用率、低复杂度、高解码效率等特点。     

基于TMS320C6416的DRM音频解码实现及优化

给出了数字广播调幅系统DRM的AAC音频解码器在定点DSP芯片TMS320C6416上的实现方案,从多方面对AAC音频解码器的关键技术进行优化.实验结果表明,算法的运行速度提高了10倍,存储器占用情况有较大改善,为DRM广播信号解码系统执行音频解码之前的解调和信道解码程序节省了很大的周期资源和处理空间.     

Effect of organic alkali on hydration of GGBS-FA blended cementitious material activated by sodium carbonate

Sodium carbonate (SC) activated ground granulated blast-furnace slag (GGBS) and fly ash (FA) is a potential substitute of traditional cement with ultra-low carbon footprint. However, its hydration rate and strength growth are limited, owing to the slow leaching of ions during the activation of weak base. In this work, 60% wet-grinded GGBS and 40% FA were blended as the binder, and two organic alkalis, i.e. triethanolamine (TEA) and triisopropanolamine (TIPA), were adopted to facilitate the ions dissolution and pozzolanic reaction of SC activated GGBS-FA blended cementitious material (SCSF). The compressive strength was tested and the hydration kinetics was studied by hydration heat and chemical shrinkage. Besides, ions leaching behavior was characterized by ICP; hydrates and microstructure were also detected by XRD, TG-DTG and SEM. Results indicated that the addition of TEA or TIPA significantly promoted the ions dissolution. 0.05% TEA increased the concentration of leached Ca²⁺, Al³⁺ and Fe³⁺ by 36%, 33% and 1545%, respectively. This solubilizing effect was also found in TIPA. Moreover, these two chemicals could promote the formation of hydrates, such as C-S(A)-H gel, hydrotalcite, calcite and aragonite, especially at the early period; these also activated the hydration process of SCSF effectively, and the compressive strength of the mortar reached above 40.0 MPa at 7 d and 48.0 MPa at 28 d. The carbon emission of the designed system is 85.9% and 55.9% lower than that of PC and strong base activated GGBS system, respectively.     

AAC中基于子带能量分布的自适应比特分配算法

针对ISO标准算法并没有考虑可用比特数小于编码所需比特数的情况而不能实现编码音质的最佳化的问题,利用人耳对音频信号中的高频部分不敏感的感知特性,根据待编码音频信号各比例因子带的能量分布情况,提出了一种新的自适应比特分配策略。结果表明,与标准算法相比,文中算法在降低编码计算量的同时能有效提高编码主观音质。     

基于MATLAB编程计算计算蒸压加气混凝土发气孔参数

将加气混凝土砌块照片中的灰度信息存入矩阵中,利用matlab对加气混凝土砌块断面照片的矩阵信息进行拉普拉斯实线性导数运算锐化孔壁边缘,再采用比度拉伸增强孔壁与孔之间的灰度值差距,进一步采用比率变换使平坦区域灰度一致。在此基础上获得任一断面上的灰度分布图,可用于研究任意发气方向上孔径变化。将经过以上处理之后的矩阵进行二值化反向处理,存入excel中可精确统计气孔总面积、孔隙率、平均气孔面积等参数。     

USB多路音频采集系统的设计与实现

提出了一种基于USB1.1的多路音频采集系统的实现方案。实际测试表明,该系统克服了现有系统中音频数据传输影响视频质量的缺陷,具有音频保真度高、成本低等突出优点。     

Evaluation of Antioxidant Properties and Mineral Composition of Purslane (Portulaca oleracea L.) at Different Growth Stages

The main objective of this research was to appraise the changes in mineral content and antioxidant attributes of Portulaca oleracea over different growth stages. The antioxidant activity was measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric-reducing antioxidant power (FRAP) assays. The iodine titration method was used to determine the ascorbic acid content (AAC). DPPH scavenging (IC(50)) capacity ranged from 1.30 ± 0.04 to 1.71 ± 0.04 mg/mL, while the ascorbic acid equivalent antioxidant activity (AEAC) values were 229.5 ± 7.9 to 319.3 ± 8.7 mg AA/100 g, total phenol content (TPC) varied from 174.5 ± 8.5 to 348.5 ± 7.9 mg GAE/100 g. AAC 60.5 ± 2.1 to 86.5 ± 3.9 mg/100 g and FRAP 1.8 ± 0.1 to 4.3 ± 0.1 mg GAE/g. There was good correlation between the results of TPC and AEAC, and between IC(50) and FRAP assays (r(2) > 0.9). The concentrations of Ca, Mg, K, Fe and Zn increased with plant maturity. Calcium (Ca) was negatively correlated with sodium (Na) and chloride (Cl), but positively correlated with magnesium (Mg), potassium (K), iron (Fe) and zinc (Zn). Portulaca olerecea cultivars could be used as a source of minerals and antioxidants, especially for functional food and nutraceutical applications.