满足国标地面数字电视和中国移动多媒体广播的发射机输出带通滤波器研究

本文通过对国标地面数字电视(DTMB)和中国移动多媒体广播(CMMB)相关技术标准进行研究,得出满足上述标准的发射机输出带通滤波器的主要指标要求.     

多种谐波源环境中高通滤波器的应用

通过对一引进工程的二阶高通滤波器的设计特点进行分析，借鉴其设计优点，以开拓滤波设备的设计思路。     

基于MATLAB的IIR数字滤波器设计

主要研究了IIR数字滤波器的设计原理及方案,重点介绍了脉冲响应不变法和双线性变换法,并以数字巴特沃斯滤波器为例介绍了其MATALB实现.     

IIR数字滤波器的计算机设计方法

推导出了从原型低通模拟滤波器转换到不同类型的IIR数字滤波器的矩阵表示方法,实现了IIR数字滤波器的计算机自动设计,并编制了一套IIR数字滤波器设计软件.通过设计实例证明,简化了IIR数字滤波器的设计程序.     

大功率整流机组滤波器的参数设计方法

研究了电解铝厂大功率可控整流系统功率因数低下的原因,分析了这种整流机组网侧谐波电流和基波感性电流。根据系统功率因数要求,给出了整流变第三线圈加装PLC型结构的滤波器中电阻、电感、电容三个参数的计算方法,在参数计算方法中着重强调了品质因数Q的选取原则。根据给出的计算公式,计算了某电解铝公司两系列整流机组滤波器参数,并与两个系列整流机组的实践效果进行了对比,从而证明了计算方法的正确性。     

基于模糊逻辑的数字滤波器设计

针对传统滤波器单一模型设计的缺点,提出一种将滤波噪声统计特性与模糊逻辑相结合的数字滤波器设计方法.该方法根据噪声统计特性,利用缩短三角型模糊函数,确定模糊逻辑滤波器的参数.通过滤波噪声标准偏差与最大滤波噪声门限的比较,提出了分别采用单值滤波和均值滤波的方法,并推导了均值滤波方法中的周期抽样数目.给出了算法具体设计步骤,包括:滤波方法选择、连续信号周期采样、模糊化数据处理和去模糊化.仿真表明,基于模糊逻辑的数字滤波器对不同标准偏差的噪声均有良好的滤波性能,并且设计经济合理,时间开销小,软硬件易实现.有工程应用价值.     

有源电力滤波器对电弧炉的电能质量改善

通过将电弧炉的非线性时变电阻模型、波动性模型以及混沌模型线性叠加,在多个原有电弧炉模型的基础上建立了可以根据实际情况和个人需求进行任意调节的综合电弧炉模型,此模型通过参数设计可以表现出电弧炉各方面的特性,通过调节还能够突出表现电弧炉某一方面的特点。应用有源电力滤波器,对所提出的综合电弧炉模型进行了谐波抑制等电能质量方面的改善。应用matalb软件进行了仿真,结果表明理想有源电力滤波器基本可以保证电弧炉不对电网电能质量造成任何影响。     

具有扰动的Chen氏混沌系统干扰抑制

研究了Chen氏混沌系统的特点.当混沌系统存在不确定因素干扰时,提出了控制混沌的新方法:使混沌系统大范围渐近稳定和进行干扰抑制.然后采用非线性系统无源性化设计混沌系统的反馈镇定控制律,利用L2性能准则进行干扰抑制.最后计算机仿真证明该方法的有效性.     

IIR数字滤波器的VHDL设计与仿真

VHDL语言是EDA设计中常用的一种IEEE标准语言,具有覆盖面广、描述能力强、可读性好、支持大规模设计及逻辑单元利用等优点,因此受到越来越多的电子工程师的青睐.数字信号处理在科学和工程技术许多领域中得到广泛的应用,本文采用一种基于FPGA的数字滤波器的设计方案,首先分析了数字滤波器的原理及设计方法,然后通过MAX+PLUSⅡ的设计平台,分别对各模块采用VHDL语言进行描述,并进行了仿真和综合.仿真结果表明,本文所设计的数字滤波器运算速度较快,系数改变灵活,有较高的参考价值.     

Adiabatic water suppression using frequency selective excitation

We tested the hypothesis that hypoxic newborn piglets can be successfully resuscitated with lower O2 concentrations than 21%. Severely hypoxic, 2-4-d-old, anesthetized piglets were randomly divided into five resuscitation groups: 21% O2 (n = 10), 18% O2 (n = 9), 15% O2 (n = 9), 12% O2 (n = 8), all normoventilated, and a hypoventilated 21% O2 group (PaCO2; 7.0-8.0 kPa, n = 9). Base excess (BE) reached -20 +/- 1 mmol/L at the end of hypoxia. After 3 h of resuscitation, BE had risen to -4 +/- 1 mmol/L in the 21% O2, 18% O2, and hypoventilated groups, but was -10 +/- 2 mmol/L in the 15% O2 group (p < 0.05 versus 21% O2 group) and -22 +/- 2 mmol/L in the 12% O2 group (p < 0.05 versus 21% O2 group). Four animals died during resuscitation, all allocated to the 12% O2 group (p < 0.05 versus 21% O2 group). Somatosensory evoked potentials (SEPs) recovered in 39 of 45 piglets, and remained present during resuscitation in all except the 12% O2 group. SEP recovered initially even in six of eight animals in the 12% O2 group, but disappeared again in all later during resuscitation. The SEP amplitude recovered to levels not significantly different from the 21% O2 group in all groups except the 12% O2 group. Plasma hypoxanthine concentrations and extracellular hypoxanthine concentrations in the striatum decreased during resuscitation to levels not significantly different from the 21% O2 group in all but the 12% O2 group (p < 0.05 versus 21% O2 group). In conclusion, severely hypoxic newborn piglets were resuscitated as efficiently with both hypoventilation and 18% O2 as with 21% O2.     

低损耗三调谐滤波器的设计与应用

有色冶炼厂不可避免地大量使用谐波源设备,而谐波的存在又严重危害了供电网络和用电没备的安全.本文主要介绍了低损耗三调谐滤波器的基本原理及参数计算,及该滤波器在吉首某冶炼厂谐波治理和无功补偿改造项目中的应用,并对在工程中遇到的一些需要注意的问题进行了分析并提出了解决措施.     

Low-frequency suppression of auditory nerve responses to characteristic frequency tones

The effects of low-frequency (50, 100, 200 and 400 Hz) 'suppressor' tones on responses to moderate-level characteristic frequency (CF) tones were measured in chinchilla auditory nerve fibers. Two-tone interactions were evident at suppressor intensities of 70-100 dB SPL. In this range, the average response rate decreased as a function of increasing suppressor level and the instantaneous response rate was modulated periodically. At suppression threshold, the phase of suppression typically coincided with basilar membrane displacement toward scala tympani, regardless of CF. At higher suppressor levels, two suppression maxima coexisted, synchronous with peak basilar membrane displacement toward scala tympani and scala vestibuli. Modulation and rate-suppression thresholds did not vary as a function of spontaneous activity and were only minimally correlated with fiber sensitivity. Except for fibers with CF < 1 kHz, modulation and rate-suppression thresholds were lower than rate and phase-locking thresholds for the suppressor tones presented alone. In the case of high-CF fibers with low spontaneous activity, excitation thresholds could exceed suppression thresholds by more than 30 dB. The strength of modulation decreased systematically with increasing suppressor frequency. For a given suppressor frequency, modulation was strongest in high-CF fibers and weakest in low-CF fibers. The present findings strongly support the notion that low-frequency suppression in auditory nerve fibers largely reflects an underlying basilar membrane phenomenon closely related to compressive non-linearity.     

Auditory suppression and frequency selectivity in older and younger adults

Age differences in auditory suppression were examined by comparing auditory-filter shapes obtained with simultaneous and forward masking at 2 kHz in young and elderly normal-hearing listeners. To compensate for the decay of forward masking, growth of masking functions were used to transform thresholds obtained with a notched-noise masker to the level of a continuous noise band that would give the same threshold values. Although both age groups exhibited smaller equivalent rectangular bandwidths (ERBs) when the filters derived from transformed thresholds were obtained with forward masking, the change from simultaneous to nonsimultaneous masking was significantly greater for young adults. Measures of the low- (Pl) and high- (Pu) frequency sides of the filters for young listeners indicated that the slopes of both sides increased following a change from simultaneous to forward masking but that the high-frequency side exhibited significantly greater sharpening. Filter slopes (both upper and lower) for older adults, in contrast, did not differ between the two masking procedures. The findings from the study are discussed as reflecting possible age differences in auditory suppression. However, it is also noted that conclusions regarding differences between filter shapes derived with simultaneous and forward masking are limited to filter parameters determined with transformed (as described above) thresholds.     

颗粒层除尘实验装置的设计

对除尘器进行了分类和比较,指出了颗粒层除尘器在高温烟气余热余能回收利用方面的优势和前景。根据实验要求,设计了一种常温下可连续工作的颗粒层除尘实验装置。详述了加灰系统、送风系统和过滤系统三大部分的设计方案,并着重阐述了双开阀的结构和工作原理,最后讲解了实验装置连续自动清灰工作的过程。     

Muscimol suppression of the dorsal cochlear nucleus impairs frequency discrimination in rats

The cochlear nucleus is composed of three sub-nuclei: the dorsal (DCN), anteroventral (AVCN) and posteroventral cochlear nucleus (PVCN). In addition to connections between these sub-nuclei, each nucleus receives frequency specific tonotopically organised input from the cochlea. Evidence suggests that connections from the DCN to the AVCN are inhibitory and organised tonotopically but the functional significance of this pathway has yet to be elucidated. The possible role of this pathway in frequency discrimination using a T-maze behavioural paradigm and DCN suppression was examined. Five rats were trained on a two choice frequency discrimination task. Once frequency difference limens for 10-30% performance above chance were determined, rats had cannulae implanted bilaterally over the DCN. After recovery rats were tested on the behavioural task with nothing, saline and the GABA agonist muscimol injected into the DCN via the cannulae. Muscimol alone significantly reduced the rats ability to perform the task. This performance decrease was attributed to an inability to discriminate high frequency and not low frequency tones suggesting that place and not temporal coding of sound was compromised by DCN suppression. These results are consistent with the hypothesis that inhibitory drive from the DCN to AVCN may be crucial for the fine tuning of frequency information.     

AQUAZUR V滤池细部的设计和应用

概述了AQUAZURV滤池的优缺点;并联系实际工作中的设计心得,着重对AQUAZURV滤池一些细部的设计及应用作了总结分析.     

电脑式煤气自洁过滤器的设计及应用

通过对韶钢动力厂焦炉煤气压缩机运行故障问题的分析，设计并应用了电脑式煤气自洁过滤器，有效地解决了煤气压缩机故障频发的问题，确保了我厂焦炉煤气的正常供应，具有可观的经济、社会和环保效益，值得在钢铁企业同行中推广应用．     

A constrained neural network Kalman filter for price estimation in high frequency financial data

In this paper we present a neural network extended Kalman filter for modeling noisy financial time series. The neural network is employed to estimate the nonlinear dynamics of the extended Kalman filter. Conditions for the neural network weight matrix are provided to guarantee the stability of the filter. The extended Kalman filter presented is designed to filter three types of noise commonly observed in financial data: process noise, measurement noise, and arrival noise. The erratic arrival of data (arrival noise) results in the neural network predictions being iterated into the future. Constraining the neural network to have a fixed point at the origin produces better iterated predictions and more stable results. The performance of constrained and unconstrained neural networks within the extended Kalman filter is demonstrated on "Quote" tick data from the $/DM exchange rate (1993-1995).     

全数字时钟恢复方案中内插滤波器的设计

介绍了全数字时钟恢复方案中采用Farrow结构高效实现内插滤波器的设计方法.提出一种计算Farrow结构内插滤波器系数的算法,使得接收机输出信号的均方误差始终最小.仿真结果表明,与传统的内插滤波器设计相比,应用本文算法的全数字同步方案提高了接收机输出均方差和输出信噪比的性能,并且降低了时钟恢复方案中内插滤波器的实现复杂度.