采用过零刺激方案提高电子耳蜗声调识别

针对目前噪声环境下电子耳蜗汉语声调和语句识别率急剧下降问题,提出了一种基于时间精细结构过零刺激方案（FSZC）。利用语音信号时间精细结构的过零点时刻产生高速脉冲刺激序列,从而不仅将时间精细结构编码到电子耳蜗语音算法中,同时采用过零点时刻非均匀的采样脉冲刺激序列,确保了语音的空间编码和时间编码。声学模拟实验表明,相比于连续交替采样策略（CIS）和过零点时刻刺激策略（ZCT）,FSZC方案在汉语声调和语句识别率上都有较大程度的提高,而且在噪声环境下对于声调和语句识别具有相对较强的抗噪性。     

压缩数据上的关系代数操作算法

针对在大数据管理中,在压缩的数据上无需解压即可进行相关操作的问题,在数据服从正态分布的前提下,根据列数据存储的特点,提出了一种新的面向列存储的压缩方法——CCA。首先,通过对列数据的长度进行归类;然后,采用抽样的方法获得重复度较高的前缀;最后,使用字典编码进行压缩,提出了列索引(CI)和列实体(CR)作为数据压缩结构来降低大数据存储的空间需求,从而直接有效地在压缩数据上支持选择、投影、连接等基本操作,并实现了基于CCA的数据库原型系统——D-DBMS。理论分析和在1 TB数据上的实验结果表明,该压缩算法能够显著提高大数据的存储效率和数据操作性能,与BAP和TIDC压缩方法相比,在压缩率分别提高了51%、14%;在执行速度上提高了47%、42%。     

Using covariance intersection for change detection in remote sensing images

In this paper, an unsupervised change detection technique for remote sensing images ac-quired on the same geographical area but at different time instances is proposed by conducting Co-variance Intersection (CI) to perform unsupervised fusion of the final fuzzy partition matrices from the Fuzzy C-Means (FCM) clustering for the feature space by applying compressed sampling to the given remote sensing images. The proposed approach exploits a CI-based data fusion of the membership function matrices, which are obtained by taking the Fuzzy C-Means (FCM) clustering of the fre-quency-domain feature vectors and spatial-domain feature vectors, aimed at enhancing the unsuper-vised change detection performance. Compressed sampling is performed to realize the image local feature sampling, which is a signal acquisition framework based on the revelation that a small collection of linear projections of a sparse signal contains enough information for stable recovery. The experi-mental results demonstrate that the proposed algorithm has a good change detection results and also performs quite well on denoising purpose.     

Folded Architecture for Digital Gammatone Filter Used in Speech Processor of Cochlear Implant

Emerging trends in the area of digital very large scale integration (VLSI) signal processing can lead to a reduction in the cost of the cochlear implant. Digital signal processing algorithms are repetitively used in speech processors for filtering and encoding operations. The critical paths in these algorithms limit the performance of the speech processors. These algorithms must be transformed to accommodate processors designed to be high speed and have less area and low power. This can be realized by basing the design of the auditory filter banks for the processors on digital VLSI signal processing concepts. By applying a folding algorithm to the second‐order digital gammatone filter (GTF), the number of multipliers is reduced from five to one and the number of adders is reduced from three to one, without changing the characteristics of the filter. Folded second‐order filter sections are cascaded with three similar structures to realize the eighth‐order digital GTF whose response is a close match to the human cochlea response. The silicon area is reduced from twenty to four multipliers and from twelve to four adders by using the folding architecture.     

Characterisation tools development for PEM electrolysers

Electrochemical impedance spectroscopy (EIS), current interrupt (CI) and current mapping (CM) were investigated as in-situ characterisation tools for PEM electrolysers. A 25 cm² cell with titanium anode and carbon cathode plates were utilised in this study. A commercial MEA consisting of 1 mg IrO₂/cm² on the anode and 0.3 mg Pt/cm² on the cathode was used. The electrocatalyst was deposited on Nafion^® membranes. The electrochemical losses in a PEM electrolyser namely: activation, ohmic and mass transfer losses were identified using EIS and CI and both the advantages and disadvantages of the methods were discussed. The current distribution over the membrane electrode assembly (MEA) at different current densities was measured using the current mapping method. It is also shown that under the given experimental conditions the current density decreases along the serpentine flow field.     

Ab INITIO COMPUTATIONAL MODELS IN MATERIALS SCIENCE: A COMMON PLAYGROUND FOR SURFACE CHEMISTRY AND SOLID-STATE PHYSICS

This article describes the usefulness of embedded cluster and periodic models to solve a number of problems in computational materials science. To this end, two different well-defined problems are selected and discussed. The first problem concerns magnetic coupling in high Tc superconductor parent compounds. It is taken to exemplify the application of quantum chemical methods to derive excited-state properties of extended systems. The second problem concerns the selectivity of a partial oxidation reaction catalyzed by a metal surface. This second example serves to illustrate the efficacy of solid-state band theory methods in the study of chemical reactions taking place at surfaces. Possible extensions of ab initio computational materials science are further discussed.     

高密度-低温柴油机燃烧理论与技术的研究与进展

本文以节能和超低排放为目标,先后开展了"早喷"预混压燃燃烧,稀扩散燃烧和复合燃烧等理论与技术的研究.阐述了其基本技术路线、优势和局限性.在此基础上.作者课题组提出了柴油机燃烧过程混合和化学时间尺度控制及燃烧路径控制概念,最终形成了高密度.低温燃烧理论,并在实验发动机上通过燃烧电子控制技术的创新实现了在欧V排放水平上柴油机高热效率和简化或取消后处理器的目标.     

悬吊氯化铵溶液液滴的结晶过程

研究了常温下悬吊氯化铵溶液液滴的结晶过程,讨论了初始液滴的大小、氯化铵浓度以及悬吊细丝对结晶过程的影响.在实验中观察到了沿液滴表面枝晶的生长过程,发现液滴成壳后的表面形态与成核时的液滴直径之间有一定的关系.为了深入了解声悬浮条件下溶液液滴的结晶过程,将两种不同条件下的结晶过程进行了比较,并由此对声悬浮液滴结晶过程做出一些推断.     

A human-machine interface evaluation method: A difficulty evaluation method in information searching (DEMIS)

A human-machine interface (HMI) evaluation method, which is named “difficulty evaluation method in information searching (DEMIS)”, is proposed and demonstrated with an experimental study. The DEMIS is based on a human performance model and two measures of attentional-resource effectiveness in monitoring and detection tasks in nuclear power plants (NPPs). Operator competence and HMI design are modeled to be most significant factors to human performance. One of the two effectiveness measures is fixation-to-importance ratio (FIR) which represents attentional resource (eye fixations) spent on an information source compared to importance of the information source. The other measure is selective attention effectiveness (SAE) which incorporates FIRs for all information sources. The underlying principle of the measures is that the information source should be selectively attended to according to its informational importance. In this study, poor performance in information searching tasks is modeled to be coupled with difficulties caused by poor mental models of operators or/and poor HMI design. Human performance in information searching tasks is evaluated by analyzing the FIR and the SAE. Operator mental models are evaluated by a questionnaire-based method. Then difficulties caused by a poor HMI design are evaluated by a focused interview based on the FIR evaluation and then root causes leading to poor performance are identified in a systematic way.     

Effects of graduated driver licensing on licensure and traffic injury rates in Upstate New York

Objective

In 2003, New York State implemented an enhanced graduated driving licensing (GDL) program that requires extended supervised driving and a passenger restriction. This study examines its safety benefit in 55 Upstate New York counties.

Methods

We analyzed fatal/incapacitating traffic injury data among 16-, 17- and 21-24-year olds for the years 2001 and 2005 using the negative binomial model. To adjust for trends in the traffic injury rate, the relative rate ratio (rRR) of 16- and 17-year olds relative to 21-24-year olds was estimated.

Results

GDL implementation was associated with a 31% reduction in the driver injury rate (rRR 0.69, 95% confidence interval (CI) 0.49-0.96), but not with any statistically significant change in the passenger injury rate (rRR 1.19, 95% CI 0.77-1.84), or pedestrian and bicyclist injury rate (rRR 1.53, 95% CI 0.89-2.62) among 16-year olds. Sixteen-year olds experienced a 21% decline in licensure rates between 2001 and 2005. GDL implementation had no appreciable impact on driver injury and licensure rates for 17- and 21-24-year olds.

Conclusions

GDL implementation is associated with a significant reduction in licensure and driver injury rate among 16-year olds. GDL implementation does not have a statistically significant impact on passenger, pedestrian, and bicyclist injury rates for 16-year olds.