基于自适应形态小波的轧机电气信号压缩方法

针对非线性、非平稳信号的数据压缩问题,提出了一种基于自适应形态小波的轧机电气信号压缩方法.结合电气信号的形态特征,采用中值算子作为形态小波的更新算子对信号进行分解,从而实现根据信号的局部形态特征,自适应地调整形态小波分解的更新算子.工业现场实际轧机电气信号的数据压缩实验证明:利用这种形态小波信号压缩方法,可以获得高压缩比的信号,并能保留信号的形态特征;同时,这种形态小波信号压缩方法运算量小,可以应用到实时性要求较高的在线监测系统中.     

信号的多项式趋势项研究和MATLAB实现

通过对确定性信号和随机信号加入线性和非线性趋势项,并用最小二乘法和小波法分别进行消除趋势项处理,比较消趋前后信号和原始信号的均值、方差和相关系数等参考量,提出不同信号类型要用不同消除趋势项的方法,才能达到理想的消趋效果。     

Monoclonal antibody anti-type I and anti-zebrin II labelling in siluriform fishes: the role of shared lineage versus shared function in polypeptide co-distributions

Vibroarthrography (VAG) is an innovative, objective, non-invasive technique for obtaining diagnostic information concerning the articular cartilage of a joint. Knee VAG signals can be detected using a contact sensor over the skin surface of the knee joint during knee movement such as flexion and/or extension. These measured signals, however, contain significant interference caused by muscle contraction that is required for knee movement. Quality improvement of VAG signals is an important subject, and crucial in computer-aided diagnosis of cartilage pathology. While simple frequency domain high-pass (or band-pass) filtering could be used for minimizing muscle contraction interference (MCI), it could eliminate possible overlapping spectral components of the VAG signals. In this work, an adaptive MCI cancellation technique is presented as an alternative technique for filtering VAG signals. Methods of measuring the VAG and reference signals (MCI) are described, with details on MCI identification, characterization, and step size optimization for the adaptive filter. The performance of the method is evaluated by simulated signals as well as signals obtained from human subjects under isotonic contraction.     

气液两相管流流型信号的小波去噪处理

流型信号能够反映气液两相管流的流动特征,它们往往会伴随着各种随机噪声,为此建立了一座气液两相流的综合试验装置,提取气液两相管流的流型信号．采用小波变换对信号样本的进行多尺度分解,利用信号和噪声在不同尺度上的特性把它们区分开来,消除噪声后再对信号进行重构,得到了较好的去噪效果．     

基于局部投影和小波降噪的弱冲击特征信号的提取

综合局部投影算法及小波变换两者的优点,提出了基于局部投影和小波降噪的弱冲击信号的提取方法.实验结果表明,局部投影算法可以将背景信号和特征信号分解到不同的子空间上,小波降噪可以有效地用于包含尖峰或突变信号的降噪,结合局部投影和小波降噪的弱冲击信号的提取方法对于微弱特征信号的提取是非常有效的.     

The fallacy of conventional signalling

All signals, with the exception of very special ones such as human verbal communication, evolve to be reliable. Communication systems that have been considered as systems of conventional signalling are reinterpreted as reliable systems by indicating the investment which increases their reliability. Examples are given from decorative patterns and set specific signals, such as status signals. The general importance of reliability is further discussed for cases such as the chemical signals within the multicellular organism, in which there is no conflict between the communicating parties. The reliability of signals which display symmetry, as is measured by the 'fluctuating asymmetry', is interpreted as a consequence of the investment required of signals that coordinate development.     

Leiomyoma and leiomyosarcoma of the gastrointestinal tracts. Arteriographic findings

Neuron responses in the chicken torus and caudal neostriatum to signals with different ecological significance (tones "white" noise, species-specific signals) were studied. It is shown that the frequency band percepted by the acoustic analyzer neurons corresponds to the frequency composition of signals emanated by chickens. Neurons selectively responding to the species-specific signals (song, alarm cries) were found in the forebrain. The specificity of the functional organization of different levels of the acoustic analyzer is considered in the light of the selectively combination principle of the signals integration, which may determine the mechanism of both innate and learned memory.     

Extreme DNA sequence variation in isolates of Aspergillus fumigatus

In previous studies on mechanomyogram (MMG) signals no analysis of these signals accompanying force generation has been performed. Therefore, we have recorded MMG signals (previously referred to as muscle sound or acoustomyographic signals) during voluntary contractions of forefinger flexor muscles in 31 young subjects. These subjects made contractions to produce force records of triangular or trapeziform shape. The peak target force amounted to 10, 20 or 40 N which represented less than 40% of maximal voluntary contraction. The MMG signals during the transient phases of force generation at three different rates were analysed. The MMG intensity level calculated for MMG records and the peak-to-peak amplitude of MMG signals correlated with both the velocity of force increase and the contraction force. The occurrence of the strongest MMG signals corresponded to changes in contractile force. Therefore, it is suggested that measurements of these parameters could be a useful tool in studies of changes in contractile force.     

LTP of AMPA and NMDA receptor-mediated signals: evidence for presynaptic expression and extrasynaptic glutamate spill-over

We have addressed the expression of long-term potentiation (LTP) in hippocampal CA1 by comparing AMPA and NMDA receptor-(AMPAR- and NMDAR-) mediated postsynaptic signals. We find that potentiation of NMDAR-mediated signals accompanies LTP of AMPAR-mediated signals, and is associated with a change in variability implying an increase in quantal content. Further, tetanic LTP of NMDAR-mediated signals can be elicited when LTP of AMPAR-mediated signals is prevented. We propose that LTP is mainly expressed presynaptically, and that, while AMPARs respond only to glutamate from immediately apposed terminals, NMDARs also sense glutamate released from terminals presynaptic to neighboring cells. We also find that tetanic LTP increases the rate of depression of NMDAR-mediated signals by the use-dependent blocker MK-801, implying an increase in the glutamate release probability. These findings argue for a presynaptic contribution to LTP and for extrasynaptic spill-over of glutamate onto NMDARs.     

Differential effects of auditory and visual signals on clock speed and temporal memory.

The effects of signal modality on duration classification in college students were studied with the duration bisection task. When auditory and visual signals were presented in the same test session and shared common anchor durations, visual signals were classified as shorter than equivalent duration auditory signals. This occurred when auditory and visual signals were presented sequentially in the same test session and when presented simultaneously but asynchronously. Presentation of a single modality signal within a test session, or both modalities but with different anchor durations did not result in classification differences. The authors posit a model in which auditory and visual signals drive an internal clock at different rates. The clock rate difference is due to an attentional effect on the mode switch and is revealed only when the memories for the short and long anchor durations consist of a mix of contributions from accumulations generated by both the fast auditory and slower visual clock rates. When this occurs auditory signals seem longer than visual signals relative to the composite memory representation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' responses to facial and vocal emotional signals in a social referencing paradigm

The independent effects of facial and vocal emotional signals and of positive and negative signals on infant behavior were investigated in a novel toy social referencing paradigm. 90 12-month-old infants and their mothers were assigned to an expression condition (neutral, happy, or fear) nested within a modality condition (face-only or voice-only). Each infant participated in 3 trials: a baseline trial, an expression trial, and a final positive trial. We found that fearful vocal emotional signals, when presented without facial signals, were sufficient to elicit appropriate behavior regulation. Infants in the fear-voice condition looked at their mothers longer, showed less toy proximity, and tended to show more negative affect than infants in the neutral-voice condition. Happy vocal signals did not elicit differential responding. The infants' sex was a factor in the few effects that were found for infants' responses to facial emotional signals.     

Controllability and safety signals exert dissimilar proactive effects on nociception and escape performance.

In the present experiments we assess the ability of exteroceptive safety signals to proactively mimic shock controllability. In Experiment 1, animals were given escapable shock, yoked inescapable shock, restraint, or yoked shock with a stimulus coincident with shock offset on Day 1 and then given inescapable shock on Day 2. Safety signals attenuated the hypoalgesia following the first shock session. On Day 2, however, animals that had been preshocked with safety signals were not less hypoalgesic than those previously restrained. Conversely, shock controllability did not attenuate the hypoalgesia following the first session but proactively attenuated hypoalgesia during the second. Unlike animals preexposed to controllable shock, those given safety signals evidenced shuttle escape deficits 24 hr following the Day 2 inescapable shock treatment. Safety signals therefore failed to exert "immunization" effects. By employing identical preshock and shuttle test procedures, in Experiment 2 we demonstrated that safety signals completely block development of the escape deficit which otherwise results from the initial inescapable shock exposure. Thus, safety signals effectively reduce the impact of shock delivered in the same session but are ineffective in reducing the effect of subsequent shock. These results suggest that distinct processes underlie the effects of controllability and safety signals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Latent timing in human conditioned avoidance.

Four experiments explored signal timing in human conditioned avoidance. Participants received discrimination training with different duration signals that announced the outcome (S+) or not (S-). Temporal discrimination and superposition of performance to S+ signals of different length (3, 6, or 9 s) was found both in within-subjects (Experiment 1a) and between-subjects (Experiment 1b) designs. S- signals also produced a temporal discrimination and superposition effect during a single test trial conducted after the meaning of the signals was reversed through instructions. Experiments 2a and 2b replicated these results in a situation in which (a) the durations of the S+ and S- signals were different (4.5 or 9 s) to prevent any temporal generalization between them (Experiment 2a), and (b) only S- signals were presented during training, precluding developing of inhibition to S- (Experiment 2b). These results show that participants time both S+ and S- signals in human conditioned avoidance, and they further suggest that the timing of a cue is independent of reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual normalization of vowels produced by sinusoidal voices.

If listeners treat sinusoidal signals as speech signals however unlike speech they may be, then perception should exhibit the common place sensitivity to the dimensions of the originating vocal tract. The present study, employing sinusoidal signals, raised this issue by testing the identification of target /bVt/, or b-vowel-t, syllables occurring in sentences that differed in the range of frequency variation of their component tones. Vowel quality of target syllables was influenced by this acoustic correlate of vocal-tract scale, implying that the perception of these nonvocal signals includes a process of vocal-tract normalization. Converging evidence suggests that the perception of sinusoidal vowels depends on the relations among component tones and not on the phonetic likeness of each tone in isolation. The findings support the general claim that sinusoidal replicas of natural speech signals are perceptible phonetically because they preserve time-varying information present in natural signals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of organizational signals on text-processing strategies.

Two hypotheses about how organizational signals influence text recal1 were tested: (a) that signals cause readers to change their text-processing strategies and (b) that signals facilitate readers' attempts to encode topic structure information but do not cause a shift in strategies. College students read and recalled a text that contained either no signals or contained headings, overviews, or summaries emphasizing the text's topic structure. At recall, students either received no cues or were reminded of the text's topics. Providing cues facilitated recall much more in the 3 conditions involving signaling than in the no-signals condition. The results are consistent with the hypothesis that organizational signals induce readers to change their text-processing strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural mechanisms for forming a perceptual decision

Cognitive and behavioral responses to environmental stimuli depend on an evaluation of sensory signals within the cerebral cortex. The mechanism by which this occurs in a specific visual task was investigated with a combination of physiological and psychophysical techniques. Rhesus monkeys discriminated among eight possible directions of motion while directional signals were manipulated in visual area MT. One directional signal was generated by a visual stimulus and a second signal was introduced by electrically stimulating neurons that encoded a specific direction of motion. The decisions made by the monkeys in response to the two signals allowed a distinction to be made between two possible mechanisms for interpreting directional signals in MT. The monkeys tended to cast decisions in favor of one or the other signal, indicating that the signals exerted independent effects on performance and that an interactive mechanism such as vector averaging of the two signals was not operative. Thus, the data suggest a mechanism in which monkeys chose the direction encoded by the largest signal in the representation of motion direction, a "winner-take-all" decision process.     

Uncertainty experiments support the roles of second-order mechanisms in spatial frequency and orientation discriminations

Previous studies of spatial frequency and orientation discrimination [Vision Res. 32, 1885 (1992)] suggest the existence of two second-order cortical mechanisms: one that mediates spatial frequency discriminations and sums signals across orientations and one that mediates orientation discriminations and sums signals across spatial frequency bands. The existence of each mechanism is tested in an uncertainty experiment in which the observer does not know which of two hypothetically pooled signals deviates from the standard but must judge whether the deviation is an increment or a decrement. No uncertainty effect is expected if the signals are completely pooled. Observed effects are compared with this expectation and with both theoretical and empirical estimates of the effects expected if the signals are processed separately. Results support the existence of the first mechanism, but not its exclusive role in mediating spatial frequency judgments, and support the exclusive role of the second mechanism in mediating orientation judgments.     

Susceptibility to varicella zoster virus infection in health care workers

Doppler ultrasound detection of abnormally high-pitched signals within the arterial waveform offers a new method for diagnosis, and potentially for prediction, of embolic complications in at-risk patients. The nature of Doppler "microembolic" signals is of particular interest in patients with prosthetic heart valves, where a high prevalence of these signals is observed. Monitoring the middle cerebral artery with 2-MHz transcranial Doppler ultrasound (TC-2000, Nicolet Biomedical; Warwick, UK), we looked for microemboli signals in 150 patients (95 women and 55 men), and found 1 or more signals during a 30-min recording in 89% of 70 patients with Bjork-Shiley valves (principally monostrut), 54% of 50 patients with Medtronic-Hall valves, and 50% of 30 patients with Carpentier-Edwards valves (p < 0.001, chi 2). In the patients with Bjork-Shiley valves, the mean number of signals per hour was 59 (range, 42-86; 95% confidence interval), which was significantly higher than the mean in patients with Medtronic-Hall and Carpentier-Edwards valves (1.5[range, 0.5-2.5] and 1 [range, 0-5.3], respectively; both p < 0.04, multiple comparisons. Bonferroni correction). In the patients undergoing serial pre- and postoperative studies, the causative role of the valve implant was emphasized. There was no correlation between the number of emboli signals and a prior history of neurologic deficit, cardiac rhythm, previous cardiac surgery, or the intensity of oral anticoagulation, in patients with prosthetic heart valves. In Bjork-Shiley patients, dual (mitral and aortic) valves were associated with more signals than were single valves. In Medtronic-Hall patients, the signal count was greater for valves in the aortic position than it was for valves in the mitral position. Comparative studies of Doppler emboli signals in other clinical settings suggest a difference in composition or size of the underlying maternal between prosthetic valve patients and patients with carotid stenosis. These studies also suggest that the signals are of gaseous origin in valve patients. The clinical significance of continuing microembolism remains to be determined.     

Detection of asymptomatic cerebral embolic signals with Doppler ultrasound

Can asymptomatic cerebral emboli be detected? With transcranial Doppler ultrasonography of the middle cerebral artery, short-duration high-intensity asymptomatic embolic signals were detected in 6 of 25 patients with carotid stenosis and in 9 of 24 with prosthetic cardiac valves, but not in 20 normal controls. In carotid stenosis the signals were usually unilateral and ipsilateral to the stenosis. Embolic signals were significantly more common in patients with mechanical valves than with pig xenografts (8/13 vs 1/11). With mechanical valves embolic signals were usually bilateral. Detection of asymptomatic emboli may allow identification of and preventive treatment in at-risk patients.     

载荷岩石材料在加载-卸荷扰动作用下声发射特性

通过在不同应力水平下对岩石试样的加载-卸荷实验,对岩石试件在不同应力状态下受到\