一种分段动态数据压缩算法

动态测试系统动态范围(DRN)宽、测试精度高、通道数多、数据冗余大,针对基于数字信号处理器的动态测试系统的特点提出了分段动态数据压缩算法及其类C语言描述和应用实例。该算法实现动态线性压缩,其压缩和重构速度快且开销极很少,用于实时多通道数据采集与分析系统,还可用于语音通信等领域。     

Smaart Live频谱测量数据的分析（二）

2观察频谱的时间变化摄谱多数音频信号都是动态范围宽的信号,包括音乐信号、语音甚至环境噪声等,其频率范围随时间有明显变化。虽然标准的RTA频谱显示对考察信号按时     

参数在线自校正模糊控制的标准压力发生系统

本文介绍了一种采用参数在线自校正模糊控制技术的标准压力发生系统 ,该系统具有动态范围宽、稳态精度高、响应速度快且无超调的优点     

叠加法测量光纤功率计非线性

介绍了全光纤化光纤功率计非线性的宽动态范围测量系统,利用该系统可以测量光纤功率计相邻量程的不连续性.文中给出了具体测量数据,并对测量结果进行了不确定度分析.     

宽范围高精度无级激光能量衰减器的研究

本文介绍了激光半主动制导武器目标模拟系统中宽范围、高精度、无级激光能量衰减单元.它由大小两个棱镜、精密位移平台、控制器、光栅尺组成.其激光能量调节原理基于朗伯定律,只需改变光束穿过物质厚度,即可改变光强.系统实现激光能量的宽范围、高精度、高动态连续无级调节,与传统的激光能量大小调节系统相比较,它解决了能量变化动态范围小、线性度不好、需要多级级联等问题,同时具有结构简单、稳定性高、加工成本低等优点.使用1 064 nm激光器进行了实验与测试,并给出了设计方案及其实现过程,对激光能量大小调节的研究起到了推动作用.     

利用VM-7衰减校准系统实现微波阻抗参量测试

通过对VM-7衰减校准系统的构成原理及阻抗参量测试方法的分析研究,充分利用其动态范围宽、灵敏度高、频率范围宽等显著优点,提出了利用VM-7衰减校准系统结合驻波比电桥来实现微波阻抗参量测试的方案,对构造原理、实现过程和测量结果的不确定度分析进行了详细介绍。经过实测验证:系统稳定性好、准确度高,可为微波阻抗参量的计量测试提供一套切实可行的解决方案。     

L.B.Bohle博乐公司 博乐PAT-NIR系统

博乐PAT-NIR（动态分析技术-近红外技术）采用宽范围的动态工艺参数Corona NIR分析技术，将实时数据以二维图形方式展现．可帮助实现最佳的工艺运行。     

浅析变频器常见故障分析和预防措施

随着电子技术的发展,大规模集成电路和计算机控制技术的发展,使得变频技术逐步具备了宽的测速范围、高的稳速范围、高的稳速精度、快的动态响应等良好的技术性能。其中以变频器应用最为广泛。本文主要探讨了变频器常见故障分析,并系统地研究了故障的防治措施。     

共轴两焦面探测信号的激光粒度测试

为了提高激光粒度仪测量宽分布范围粒径的能力,根据衍射原理,提出扩大测试动态范围的方法.该方法使用共轴的双透镜,在两个焦平面同时探测信号,将这些信号合成后经数据处理得到粒子尺寸分布.模拟计算表明,使用两个100mm焦距的透镜和两个32环的多元探测器可测量粒径为l～2000 μm的颗粒,动态范围为2000∶1.这种方法在不需更换镜头、不改变探测器轴向位置的情况下可以测量较大量程内的粒径分布.     

关于小波分形压缩算法若干相关技术的研究

在简单介绍小波分形算法的基础上，从理论和技术两方面深入地研究了小波技术引入分形压缩算法后对传统分形压缩算法的影响，此项研究为今后分形压缩算法中充分利用小波分析特有的优点，开发出更为有效的基于小波变换的分形压缩算法提供参考和理论依据。     

Contrast imaging by non-overlapping dual frequency band transmit pulse complexes

SURF contrast imaging, as described previously in the literature, is a contrast agent detection technique achieved by processing of the received signals from transmitted dual frequency band pulse complexes with overlapping high-frequency (HF) and low-frequency (LF) pulses. The transmitted HF pulses are used for image reconstruction, whereas the transmitted LF pulses are used to manipulate the scattering properties of the contrast agent. As with harmonic contrast agent detection techniques, nonlinear wave propagation will, in most situations, also limit the specificity with the SURF contrast technique when transmitting overlapping HF and LF pulses. The present paper proposes an alternative SURF contrast imaging technique using transmit dual frequency band pulse complexes with non-overlapping HF and LF pulses. If the frequency of the LF manipulation pulse is close to the bubble resonance frequency, numerical simulations indicate a significant ring-down effect of the LF bubble radius response. Utilizing this bubble ring-down effect and transmitting the HF pulse just after the LF pulse, a contrast agent specificity approaching infinity accompanied by a contrast agent sensitivity only for contrast bubbles having resonance frequencies within a narrow frequency range may be obtained.     

A method for accurate estimation of the fatigue damage induced by bimodal processes

This paper presents a method for calculating the fatigue damage from a stochastic bimodal process, in which the high frequency (HF) and low frequency (LF) components are narrowband Gaussian processes. Rainflow cycle counting identifies the following: small but numerous cycles, and large but fewer ones. In existing methods, the small-cycle amplitudes are assumed to be identical to that of the HF cycles, whereas the large-cycle amplitudes are approximated as the sum of the HF and LF amplitudes. The novelty of the present approach lies in the recognition and incorporation of two effects, which concern the reduction of the small-cycle amplitudes caused by the LF process, and the offset between the HF and LF peaks. Parametric studies are conducted, investigating a wide range of parameters. Using time domain simulation as a benchmark, the present method is found to provide a vast improvement over existing methods, with a root-mean-square error of 1%.     

汽车内驾驶员语音增强评价研究

驾驶员语音增强质量的评价指标是保证语音增强算法性能的关键,而现有的语音增强质量评价方法不能准确地反映人对声音感知的主观性。针对上述问题,分析了言语可懂度指数对语音增强算法评价的适用性,并在某品牌汽车上进行实验。通过在汽车内建立均匀线性传声器阵列来对驾驶员语音进行信号采集,然后利用波束形成算法对阵列中不同传声器组合的语音信号进行增强,得到汽车在不同行驶速度时不同阵列组合的语音增强结果。使用信噪比和言语可懂度指数分别对实验得到的语音增强结果进行评价,结果表明言语可懂度指数更适合评价汽车内驾驶员的语音增强算法的性能。     

融合人脸表情的手语到汉藏双语情感语音转换

针对聋哑人与正常人之间存在的交流障碍问题,提出了一种融合人脸表情的手语到汉藏双语情感语音转换的方法。首先使用深度置信网络模型得到手势图像的特征信息,并通过深度神经网络模型得到人脸信息的表情特征。其次采用支持向量机对手势特征和人脸表情特征分别进行相应模型的训练及分类,根据识别出的手势信息和人脸表情信息分别获得手势文本及相应的情感标签。同时,利用普通话情感训练语料,采用说话人自适应训练方法,实现了一个基于隐Markov模型的情感语音合成系统。最后,利用识别获得的手势文本和情感标签,将手势及人脸表情转换为普通话或藏语的情感语音。客观评测表明,静态手势的识别率为92.8%,在扩充的Cohn-Kanade数据库和日本女性面部表情(Japanese Female Facial Expression,JAFFE)数据库上的人脸表情识别率为94.6%及80.3%。主观评测表明,转换获得的情感语音平均情感主观评定得分4.0分,利用三维情绪模型(Pleasure-Arousal-Dominance,PAD)分别评测人脸表情和合成的情感语音的PAD值,两者具有很高的相似度,表明合成的情感语音能够表达人脸表情的情感。     

Infections Recurrent empyema due to Salmonella enteritidis in a patient on hemodialysis

In end‐stage renal failure, impaired renal catabolism leads to retention of beta 2 microglobulin (ß2M), identified as the major constituent of hemodialysis (HD) related amyloidosis. It has been previously shown that, while using a high flux (HF) HD membrane, nocturnal hemodialysis (NHD) with its increased time and frequency provides a much higher clearance of ß2M compared to conventional HD. We compared serum ß2M levels between low flux (LF) and HF in a group of 9 NHD patients who dialyse 8 hours 6 nights/week. Fresenius polysulfone LF membrane size F6‐F8 HPS dialyser were used for the first 15 months (mth) of NHD (SA 1.3–1.8 m²). Subsequently, polysulfone HF FX80 dialyzer were used (SA 1.8 m²). Blood flow and dialysate flow rates were unchanged throughout the study. ß2M levels were measured at 6, 12, 15 mth on LF and at 6, 12 mth on HF. Albumin, homocysteine (Hcy), and phosphate (Phos) levels were also recorded at these times. ß2M levels trended upwards during the 15 mth on LF (36.6 ± 10.57 at 6 mth vs 47.1 ± 11.7 at 15 mth). On introduction of HF, there was a significant fall in ß2M at 6 mth to 12.4 ± 3.5 (p < 0.003), while ß2M levels were unchanged at 12 mth of HF. A downward trend in Hcy levels with the use of HF was noted (12.9 ± 2.9 at 0 mth Vs 11.1 ± 3.7 at 12 mth). Plasma albumin and Phos levels remained unchanged as did the use of Phos supplementation. Levels of ß2M continued to rise on NHD with LF, indicating inadequate clearance. With the introduction of HF there was a significant fall in ß2M levels consistent with improved clearance. The implications of this are that ß2M clearance may be time and frequency dependent only if dialyser membrane flux is adequate.     

改进的Kullback-Leibler复非负矩阵分解语音增强算法

针对单通道非负矩阵分解语音增强算法忽略相位信息的问题，提出了一种改进的Kullback-Leibler复非负矩阵分解的语音增强算法。该算法考虑到传统非负矩阵分解算法在复频域中增强语音时目标函数的影响，构建了一种适用于复频域的Kullback-Leibler散度下的目标函数，同时采用频谱一致性约束相位谱补偿算法，使其重构出的语音数据相位谱得到进一步的调制。实验结果表明，对于不同的非平稳噪声，所提出的算法在不同信噪比下均取得了较好的语音增强效果，尤其在低信噪比条件下（0 dB以下）语音增强效果较为明显，性能评估指标的增量较高，较好地克服了由传统相位谱补偿算法造成的信源失真率较低的缺点，进一步减少失真，抑制背景噪声，实现语音增强。     

The Current SI Seen From the Perspective of the Proposed New SI

A revised International System of Units (SI) proposed by the International Committee for Weights and Measures is under consideration by the General Conference on Weights and Measures for eventual adoption. Widely recognized as a significant advance for both metrology and science, it is defined via statements that explicitly fix the numerical values of a selected set of seven reference constants when the values of these constants are expressed in certain specified units. At first sight this approach to defining a system of units appears to be quite different from that used to define the current SI. However, by showing how the definitions of the seven base units of the current SI also fix the numerical values of a set of seven reference constants (broadly interpreted) when the values of these constants are expressed in their coherent SI units, and how the definition of the current SI can be recast into the same form as that of the revised SI under consideration, we show that the revision is not as radical a departure from the current SI as it might initially seem.     

Correction of H3+ contributions in hydrogen isotope ratio monitoring mass spectrometry

Two fundamentally different approaches, termed "pointwise" and "peakwise," are currently used to correct hydrogen isotope ratio monitoring data for the presence of H3+ ion contributions. Consideration of the underlying assumptions shows that the peakwise approach is valid only for peaks with the same functional shape and only when background signals do not vary. The pointwise correction is much more versatile and can be used even when peak shapes and sizes, as well as background signals, vary significantly. It is not exact and is limited in accuracy by (1) the signal-broadening effects of electronic time constants, (2) the analog-to-digital conversion frequency, and (3) the highest frequency of the sample signal. To minimize errors for typical gas chromatographic signals, time constants of <500 ms and analog-to-digital sampling intervals of < or =250 ms are needed. Errors are further minimized by matching sample and standard peaks in both amplitude and D/H ratio. Using the pointwise algorithm, we demonstrate that a series of 14 homologous n-alkanes varying in concentration over a 5-fold range can be analyzed with a mean precision of 2.3 per thousand and no systematic errors.     

SURF imaging for contrast agent detection

A contrast agent detection method is presented that potentially can improve the diagnostic significance of ultrasound contrast agents. Second order ultrasound field (SURF) contrast imaging is achieved by processing the received signals from transmitted dual frequency band pulse complexes with overlapping high-frequency (HF) and low-frequency (LF) pulses. The transmitted HF pulses are used for image reconstruction, whereas the transmitted LF pulses are used to manipulate the scattering properties of the contrast agent. In the present paper, we discuss how SURF contrast imaging potentially can overcome problems and limitations encountered with available contrast agent detection methods, and we give a few initial examples of in vitro measurements. With SURF contrast imaging, the resonant properties of the contrast agent may be decoupled from the HF imaging pulses. This technique is thus especially interesting for imaging contrast bubbles above their resonance frequency. However, to obtain adequate specificity, it is typically necessary to estimate and correct for accumulative nonlinear effects in the forward wave propagation.     

Speech Quality Evaluation: A New Application of Digital Watermarking

Speech quality evaluation is an important research topic. The traditional way for speech quality evaluation is using subjective tests. They are reliable, but very expensive, time consuming, and cannot be used in certain applications such as online monitoring. Objective models, based on human perception, were developed to predict the results of subjective tests. The existing objective methods require either the original speech or complicated computation model, which makes some applications of quality evaluation impossible. In this paper, we propose a novel speech quality evaluation method using digital watermarking. Our algorithm evaluates the speech quality without the need of reference speech or any computational model. The watermark is embedded in the discrete wavelet domain or temporal domain of a speech signal by using quantization technique. This algorithm can evaluate perceptual quality of speech that is distorted by Gaussian noise, MP3 compression, low-pass filtering, and packet loss. The experimental results show that the method yields accurate quality scores which are very close to the results of the perceptual evaluation of speech quality