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71.
在物联网感知层中,用于信息采集的感知层节点需要根据隐私、安全或定制消费等需要,按不同级别提供授权用户的数据访问,这导致传统的访问控制方案无法满足用户安全高效的按需访问需求.为此,提出了一种分层访问控制方案.将同安全级别感知节点划分为一个层次节点,由层次节点之间形成的偏序关系构成一个分层的访问控制模型.本方案的优势体现在:每个用户和分层节点仅存储单个密钥材料,通过密钥推导获得访问当前及下层所有资源的密钥值,减少存储开销的同时提高了系统的安全强度;支持层次节点的动态扩展及密钥材料的动态更新;满足标准模型下的可证明安全及其他扩展安全.分析表明,方案能很好地满足物联网感知层的访问控制需求. 相似文献
72.
由于评价图像Hash性能时,要求对两幅图像是否在感知上相似做出判断,因此针对这一需求,提出了一种衡量感知相似程度的评价测度。该测度的确定是先对图像进行低通滤波,再进行图像重叠分块;然后运用相关系数检测法计算每一对分块的相似程度,并对相似系数归一化,再分别计算若干个最小和最大的归一化相似系数的乘积;最后用最小相似系数乘积与最大相似系数乘积的比值作为感知相似性的测度。实验结果表明,该测度不仅可有效反映图像视觉质量的变化,而且能较好地区分两幅图像是否存在重要的视觉差异,其对感知相似进行评价的性能优于峰值信噪比。 相似文献
73.
王顺琼 《昆明冶金高等专科学校学报》2009,25(3):67-70
由于工矿企业负荷的感性性质,国家采取“功率因素调整电费”来收取电费,通过分析“功率因素调整电费”的计算方法,说明工矿企业必须要进行无功补偿,提高用电设备的功率因数,从而获得更大的经济效益的重要意义。 相似文献
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Perceptual auditory filter banks such as Bark-scale filter bank are widely used as front-end processing in speech recognition
systems. However, the problem of the design of optimized filter banks that provide higher accuracy in recognition tasks is
still open. Owing to spectral analysis in feature extraction, an adaptive bands filter bank (ABFB) is presented. The design
adopts flexible bandwidths and center frequencies for the frequency responses of the filters and utilizes genetic algorithm
(GA) to optimize the design parameters. The optimization process is realized by combining the front-end filter bank with the
back-end recognition network in the performance evaluation loop. The deployment of ABFB together with zero-crossing peak amplitude
(ZCPA) feature as a front process for radial basis function (RBF) system shows significant improvement in robustness compared
with the Bark-scale filter bank. In ABFB, several sub-bands are still more concentrated toward lower frequency but their exact
locations are determined by the performance rather than the perceptual criteria. For the ease of optimization, only symmetrical
bands are considered here, which still provide satisfactory results. 相似文献
78.
The authors attempted to identify perceptual mechanisms that pick up information for initiating a run to catch fly balls and for judging their landing locations. Fly balls have been shown to be tracked with the eyes and head (R. R. D. Oudejans, C. F. Michaels, F. C. Bakker, & K. Davids, 1999). This raised the question of whether constraining eye and head movements of experienced baseball players by having them wear eye-movement-preventing goggles (eye movements would lead to losing sight of the ball) or a head-movement-preventing neck brace, or both, would limit their capacity (a) to start running in the correct direction and (b) to make correct judgments about the balls' landing locations. Restrictions had minimal effects on response accuracy, but response latency was affected. The goggles increased latency of both running and judging. Moreover, the neck brace decreased judgment time, particularly for difficult balls, suggesting that head stability is important for making judgments. High performance levels suggested that the perceptual system was flexible; that is, different parts of the system can perform the same function. The implications of these findings for perceptual mechanisms are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
79.
Three studies explore the manner in which one's mood may affect the use and impact of accessible information on judgments. Specifically, the authors demonstrated that positive and negative moods differentially influence the direction of accessibility effects (assimilation, contrast) by determining whether abstract traits or concrete actor-trait links are primed. Study 1 investigated the impact of positive versus negative mood on the judgmental impact of trait-implying behaviors and found that positive moods lead to assimilation and negative moods to contrast. In Study 2, this effect was replicated in a subliminal priming paradigm. In Study 3, it was demonstrated that the type of information activated by trait-implying behaviors is indeed mood dependent, such that abstract trait information is activated in a positive mood, whereas specific actor-trait links are activated in a negative mood. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
80.
In daily life (e.g., in the work environment) people are often distracted by stimuli that are clearly irrelevant to the current task and should be ignored. In contrast, much applied distraction research has focused on task interruptions by information that requires a response and therefore cannot be ignored. Moreover, the most commonly used laboratory measures of distractibility (e.g., in the response-competition and attentional-capture paradigms), typically involve distractors that are task relevant (e.g., through response associations or location). A series of experiments assessed interference effects from stimuli that are entirely unrelated to the current task, comparing the effects of perceptual load on task-irrelevant and task-relevant (response competing) distractors. The results showed that an entirely irrelevant distractor can interfere with task performance to the same extent as a response-competing distractor and that, as with other types of distractors, the interfering effects of the irrelevant distractors can be eliminated with high perceptual load in the relevant task. These findings establish a new laboratory measure of a form of distractibility common to everyday life and highlight load as an important determinant of such distractibility. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献