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LD-CELP语音编码算法中矢量量化过程的改进 总被引:1,自引:0,他引:1
本文介绍了LD-CELP算法的基本原理,在分析其编码的矢量量化过程的基础上提出了一种旨在提高编码速度的改进方案.模拟实验表明,改进算法的编码速度平均提高了一倍.虽然信噪比有所下降,但下降幅度仅为1.2dB,依然能够保证编码质量. 相似文献
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本文首先研究了不稳定线性离散时间系统的最优线性滤波器设计问题,利用状态观测器结合互质分解方法,将不稳定系统的最优线性滤波问题转化成可解的模型匹配问题,从而可利用已有的逐点优化算法进行求解,推广了线性滤波器的逐点优化设计方法.然后,本文还进一步研究了线性离散时间系统线性滤波器的最优性问题,从理论上证明了线性离散系统的线性滤波器能与非线性滤波器达到相同的最优性. 相似文献
75.
《Food research international (Ottawa, Ont.)》2003,36(6):635-642
The effect of osmotic dehydration on the volatile fraction of kiwi fruit was studied, as well as the effect of freezing and frozen storage. Osmotic treatments were carried out in sucrose solutions until the kiwi fruit reached 30°Brix, at atmospheric pressure (OD) and by applying a vacuum pulse (PVOD), by using 45 and 65°Brix sucrose. Volatile compounds of fresh, dehydrated and frozen-stored (at −18 °C for 1 month) samples were obtained by simultaneous distillation-extraction, and analyzed by GC-MS. Osmotic dehydration provoked formation of esters and a decrease in aldehydes and alcohols, depending on the dehydration treatment applied, which is similar to what occurs during kiwi ripening. A severe reduction of all volatile compounds occurred after one month in frozen storage, which smoothes the changes induced by osmotic treatments. Only small differences between dehydrated and non-pretreated frozen/thawed samples could be recognized. 相似文献
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基于光干涉原理的液晶空盒盒厚测量 总被引:1,自引:1,他引:0
液晶空盒厚决定了液晶盒中液晶层的厚度,对整个液晶显示器件的光电特性、底色及响应速度等有很大的影响。因此,如何准确地测量空盒盒厚具有实际的应用价值;本文从光干涉原理出发,推导出测量液晶空盒盒厚的简单而准确的方法,此方法适用于各种排列及任意扭曲角的液昌空盒,具有误差小、设备简单、操作简便等特点,充分满足了液晶显示器件生产厂家进行盒厚过程监控和优化年设计的需要。 相似文献
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《Geotextiles and Geomembranes》2020,48(5):614-624
Clogging effect surrounding prefabricated vertical drains (PVDs) is a typical problem when vacuum preloading is applied to a dredged fill foundation. A large-scale model test was designed to clarify the cause and mechanism of the clogging effect, and the basic physical and mechanical parameters of the soil in the clogging zone were tracked during the test. The results demonstrated that a clogging zone was formed around the PVD in the early stage of improvement with conventional vacuum preloading, and the boundary of the clogging zone was approximately 0.2–0.4 of the boundary radius. The clogging zone surrounding the PVD was formed because of the overall movement of the soil toward the PVD under the high vacuum pressure gradient, rather than fine particle migration. The soil in the clogging zone exhibited permeability anisotropy and equivalent ‘smear’ effect. The permeability ratio (kh/kv) was less than 1, and the ratio of horizontal permeability coefficients at the test distances of 45 cm and 10 cm were 9.6 at a depth of 20 cm and 8.9 at a depth of 80 cm. An analysis of the microstructure of the soil in the clogging zone demonstrated that the clay particles tended to be vertically oriented. The re-orientation of the clay particles reduced the horizontal permeability coefficient and led to the permeability anisotropy of the soil in the clogging zone. Thus, decrease in the horizontal permeability coefficient and equivalent ‘smear’ effect of the soil in the clogging zone affect the consolidation of dredged fill, which leads to the clogging effect. The permeability anisotropy also slightly affects consolidation. 相似文献
80.
《LWT》2005,38(3):221-225
Quantitative and qualitative distribution of carotenoids in meat and shell of major marine crab (Charybdis cruciata) and fresh water crab (Potamon potamon) from Indian waters was assessed. The total carotenoid content was low in both species of crabs analysed, highest being 11.0 μg/g in shell of marine crab. Thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) of carotenoid extracts indicated that the marine crab contained astaxanthin and its esters as major carotenoids and zeaxanthin was major carotenoid in fresh water crab extract. Astaxanthin and its esters contributed 67.6 and 65.5 g/100 g of total carotenoids in meat and shell of marine crab. The zeaxanthin content (g/100 g) in the carotenoid extract of meat and shell of fresh water crab was 42.0 and 74.8 of total carotenoids. The carotenoid extracts from both the crabs had higher level of unsaturated fatty acids. Oleic acid (C18:1) and palmitoleic acid (C16:1) were the predominant unsaturated fatty acid in carotenoid extract from meat of marine and fresh water crab, respectively. In the carotenoid extract from shell, eicosenoic acid (C20:1) in marine crab and linolenic acid (C18:3) in fresh water crab were the major unsaturated fatty acids. 相似文献