A high payload frequency-based reversible image hiding method

To provide both a high payload capacity and a good stego-image quality, a high payload frequency-based reversible image hiding (HPFRIH) method was presented in this paper. These performances can be achieved by transforming a cover image from the spatial domain into the frequency domain through Haar digital wavelet transform (HDWT) method followed by an adaptive arithmetic coding method to encode the HDWT coefficients in a high-frequency band. The HPFRIH method was used to conceal both the compressed data and the secret data in the high-frequency band. This simple method can completely reconstruct the cover image only from the stego-image. Moreover, experimental results showed that the HPFRIH method offers both impressive hiding capacity and satisfied stego-image quality.     

基于分形理论的图象编码改进算法

基于分形理论的图象编码算法可以获得比经典图象编码算法高得多的压缩比，是很有潜力的一种算法。基本的分形图象编码技术虽然有许多优点，但其细码时间长，匹配复杂，从实用考虑，还须从多方面进行改进以提高性能。本文给出一种自适应的改进算法，利用混合编码将块截短编码（BTC）与分形编码技术相结合，同时采用三级分决技术和块分类技术，使压缩比可在20～256之间随图象特点而取值，此算法在信噪比（PSNR）方面亦有所提高。     

数字图象在广播电视综合信息网中的应用

首先介绍数字图象通信的意义、优点及压缩编码技术的进展，然后介绍某一广播电视综合信息网中数字图象通信的应用。     

JPEG encryption for image rescaling in the encrypted domain

This work proposes a novel protocol of encrypting the JPEG image suitable for image rescaling in the encrypted domain. To protect the privacy of original content, the image owner perturbs the texture and randomizes the structure of the JPEG image by enciphering the quantized Discrete Cosine Transform (DCT) coefficients. After receiving the encrypted JPEG image, the service provider generates a rescaled JPEG image by down-sampling the encrypted DCT coefficients. On the recipient side, the encrypted JPEG image rescaled by the service provider can be decrypted to a plaintext image with a lower resolution with the aid of encryption keys. Experimental results show that the proposed method has a good capability of rescaling the privacy-protected JPEG file.     

工业烟气黑度监测系统工程技术研究

利用远程监控技术,采集企业违规排放烟气图像,并通过计算机图像识别技术实现对排放黑烟进行自动监测,自动分析其黑度等级,为环保执法提供依据。文章是根据环境保护对烟尘排放的具体技术要求,设计了一套城市烟气黑度自动监测系统解决方案并付诸工程实施。重点叙述了烟气黑度识别技术、无线宽带网建设、图像传输技术等项目建设的关键与技术难点。系统建成后,有效解决了工业黑烟排放污染源的监控。该系统可靠,操作简便,监控直观,达到了系统预期的工程目标,此工程技术值得在智慧城市建设中推广应用。     

网格编码矢量量化在SAR原始数据压缩中的应用

本文提出了一种结合传统的块自适应量化与网格编码矢量量化对SAR原始数据进行压缩的方法。首先对SAR原始数据实施块自适应量化以减小数据的动态范围,然后对块自适应量化后的数据进行网格编码矢量量化。该方法在考虑了SAR原始数据特性的基础上较好地利用了矢量的空间相关性和信号的时间相关性,进一步提高了量化增益。仿真结果表明,该方法在SAR原始数据的压缩中取得了很好的效果。     

Impact of compression,physical aging,and freezing rate on the crystallization characteristics of an amorphous sugar matrix

Amorphous matrices made up of sugar molecules, are frequently used in food and pharmaceutical industries. A drawback to their use is that they are susceptible to collapse, as a result of water uptake and an increase in temperature and subsequently crystallize. Herein, the crystallization characteristics of amorphous sugar (sucrose and α-lactose) preparations were analyzed, with the purpose of obtaining knowledge that could lead to the prediction of how long the amorphous state is retained under various conditions. The impact of compression, physical aging and freezing rate on the induction period (t_ind) for crystallization were examined. Freeze-dried sugar samples were compressed at 74 or 443 MPa (5 min) and then rehumidified at specified RHs. Some freeze-dried sucrose samples were physically aged, and alternatively freeze-drying was conducted under different conditions. The isothermal crystallization of the prepared samples at different temperatures (T), the glass transition and the crystallization temperature (T_cry) were measured, using differential scanning calorimetry. The compression markedly decreased the t_ind, while significantly lowered the hygroscopicity. Physical aging and slower-freezing also shortened the t_ind. The t_ind was found to be correlated exclusively with (T_cry–T), regardless of rehumidification, compression, sugar type, physical aging and freezing rate in the freeze-drying process.     

Cryogelation of cereal β-glucans: structure and molecular size effects

The effects of molecular size and fine structure of mixed-linkage cereal (1→3), (1→4) β- -glucans (β-glucans) on their cryogelation behavior were investigated. Values of apparent molecular weight (M_w) for oat β-glucans ranged between 65 and 200×10³, whereas the respective values for both barley and wheat β-glucan preparations were about 200×10³. The fine structure of cereal β-glucans, as assessed by high-performance anion-exchange chromatography of the cellulosic oligomers released by the action of lichenase, revealed differences in the relative amounts of 3-O-β-cellobiosyl- -glucose (DP3) and 3-O-β-cellotriosyl- -glucose (DP4) units only among the different genera of cereals; the weight percent of DP3 units estimated as 67.1, 63.3, and 55.3–55.8% for wheat, barley, and oat β-glucans, respectively. Aqueous β-glucan solutions (1–3% w/v) were subjected to 12 freezing (−18 °C for 24 h) and thawing (5 °C for 24 h) cycles. The phenomenological appearance of the gelled materials obtained after this process as well as the yield of cryostructurates were influenced by the initial solution concentration, the number of freeze–thaw cycles, as well as by the molecular features of the β-glucans. Such effects were unraveled by studying the cryogelation process with differential scanning calorimetry (DSC), small strain dynamic rheometry, and large deformation mechanical measurements. For the cereal β-glucan cryogels the storage modulus, G′, increased and the tan δ decreased with decreasing polysaccharide molecular size and with increasing initial solution concentration, number of freeze–thaw cycles, and trisaccharide segments in the polymeric chains. The apparent melting enthalpy values (ΔH) of β-glucan cryostructurates, as determined from the DSC endothermic peaks, increased with decreasing molecular size and with increasing amount of cellotriose units, but they were independent of the number of freeze–thaw cycles. The DSC melting temperature of the gel network was found to increase with the molecular size and amount of DP3 units of β-glucans. Moreover, large deformation mechanical tests (compression mode) revealed an increase in strength of cereal β-glucan cryogels with increasing molecular size and decreasing trisaccharide units in the polysaccharide preparation.     

Relationship between collagen characteristics,lipid content and raw and cooked texture of meat from young bulls of fifteen European breeds

Variations in texture were determined for 10 day aged raw and cooked Longissimus thoracis (LT) muscle from 436 bulls of 15 European cattle breeds slaughtered at an age of 13–16 months. Variations in texture were related to differences in pH 24 h post-mortem, sarcomere length, collagen characteristics and lipid content. The shear force of cooked meat samples varied from 43.8 to 67.4 N/cm². Simmental, Highland and Marchigiana cattle had the highest shear force values and Avileña-Negra Ibérica, Charolais, Casina and Pirenaica cattle had the lowest values. Cooked meat toughness showed a weak negative correlation to lipid content (P < 0.001) but no correlation to collagen characteristics. Raw meat texture measured by compression correlated positively (P < 0.001) with total and insoluble collagen. In conclusion, collagen characteristics showed correlation to raw meat texture but not to cooked meat toughness of LT muscle in European young bulls.     

锌铝超塑性合金超塑压缩试验研究

对Ｚｎ－２２％Ａｌ超塑性合金进行了等温超塑压缩试验。在相同的温度、变形速率条件下，研究了不同的变形强度与流动应力及硬度，以及在相同的温度、变形程度条件下，不同的变形速率与流动应力等的关系。