Spectral methods for principal components analysis of event-related brain potentials

Principal components analysis has been a widely used method for the analysis of event-related, electrical brain potentials (ERPs). Recent emphasis has been placed on measuring the topography of ERPs, as derived from the instantaneous measurements from multiple locations, and on defining diagnostic differences in ERPs among various clinical populations. One goal of the present paper is to discuss inherent difficulties in utilizing PCA as an analytical technique in multiple location and multiple group studies. Another goal is to demonstrate the utility of spectral analysis and its equivalency to PCA when the signal imbedded in stationary noise model is used. Spectral analysis readily permits analysis of multiple lead multiple group studies.     

Multivariate spectral methods for the analysis of event-related brain potentials

The purpose of this article is to present some useful mathematical models for the analysis of multiple electrode event-related brain potential (ERP) experiments. We describe a multivariate spectral method for eye-movement removal and we also describe a multivariate spectral method for the analysis of multiple lead repeated measures data. The complex T2 and the complex Behrens-Fisher Problem are also discussed. All of the above methods are applied to experimental ERP data for four electrodes, two groups and two repeated factors.     

Development of a knowledge-base for automatic monitoring of renal function of intensive care patients over time

Renal dysfunction is a major problem in the management of critically ill patients. Monitoring of renal parameters over time is a prerequisite for detection of any significant deterioration of kidney function. Thus, we developed a knowledge-base for the dynamic monitoring of renal function of critically ill patients. A database with renal parameters of 750 intensive care patients was analyzed for distribution of parameters within predefined intervals of the creatinine clearance. Additionally, a subgroup of 11 patients with (quite) normal renal function over 11 days was selected and the daily variability of renal parameters was analyzed. An interdisciplinary expert team selected a set of nine clinically relevant renal parameters and formulated, on the basis of the data analysis and the parameter set, eight definitions of renal function, which represent four levels of renal performance. These definitions were arranged into an hierarchical structure, considering only clinically relevant changes of renal function. A change from one functional state to another inside of 2 days indicates a relevant alteration of renal function. Monitoring of time courses can additionally be performed by statistical analysis of the daily variability of parameters and comparison with their 'normal' variability. Moreover, rules were established for the plausibility check of results and interpretations of single parameters and parameter sets formulated.     

A miniature spindle motor with fluid dynamic bearings for portable storage device applications

This paper presents the design and fabrication of a miniature axial-gap spindle motor for small-form-factor optical storage applications. The motor features a fluid dynamic bearing (FDB) and is characterized by a high mechanical rigidity, excellent dynamic characteristics, and a zero cogging torque. The performance of this FDB motor is evaluated experimentally using a laboratory-built prototype. The results show that the motor has an excellent dynamic response, a small axial repeatable runout, a small tilt angle, a high rotational speed, and a low operating current. Furthermore, with overall dimensions of just 15.5 × 3.3 mm, the FDB motor is around 80% smaller than that presented by the current group in a previous study (Liu et al., J Magn Magn Mater 304:362–364, 2006). Consequently, the proposed motor represents an ideal solution for both existing and emerging miniaturized portable storage device applications.     

一种用于电子产品的温湿度记录装置

环境的温湿度对电子产品的质量是致命的,如何有效管理存放电子产品的环境温湿度以减少企业损失是企业的重要任务.提出了一种用于电子产品温湿度记录的装置,可对温湿度进行实时显示及记录,并带有USB输出口对数据进行输出,获取装置采集的数据.系统具有体积小、功耗低、操作简单等特点,可以记录电子产品长期存储环境中的温度与湿度,也可以用于其他需要测量温湿度的场合,在结构设计上采用尽可能小的结构,并采用铁磁装置,便于记录装置的放置,具有广泛的应用前景.     

一种便携式开关柜局部放电检测仪器的设计

为实现对开关柜内部局部放电的带电检测并保证其检测结果准确,提出了一种将超声波法(AE)与暂态对地电压法(TEV)相结合的同步联合检测方法,并研制了检测装置。该装置前端采用12位的ADS805模数转换器,主控部分采取FPGA+ARM的结构来实现,数据处理部分采用i MX257为核心,不但提高了检测系统的可靠性,并且具有丰富的人机交互界面。     

A portable device for the assessment of dynamic visual acuity

Dynamic visual acuity (DVA) thresholds are among the few visual functions predictive of automobile crashes. DVA is also sensitive to alcohol and aging. However, measuring DVA is awkward because there is no standardized, efficient, flexible apparatus for DVA assessment. In this project, we developed a prototype of an automated, portable DVA system using a low-energy laser, and we compared this laser DVA with the traditional device in two within-subjects, repeated measures designs. The two studies included 48 participants (22 males and 26 females with an average age of 18.33 years). The most important findings were that: (1) retest reliabilities of the two DVA devices were comparable and higher with the laser; (2) average correlations between the two devices were r = 0.62 (p < 0.01) and r = 0.65 (p < 0.01) for the two designs respectively; and (3) after correction for reliability attenuation these improved to r = 0.92 and r = 0.78. These findings indicate that a flexible DVA laser device can be developed to measure the same construct as the more traditional bulky DVA device.     

基于OMAP-L138的便携式设备状态监测与诊断仪设计

提出基于OMAP-L138的便携式设备状态监测与诊断仪的设计方案。介绍了其软硬件结构设计,重点对数据采集部分的硬件及数据采集模块的软件设计做了详细的介绍。利用了ARM核控制处理优势与DSP核数字处理能力,实现低功耗高性能的优点。     

Measuring and examining traffic sign comprehension with event-related potentials

Cognition, Technology & Work - Accurate understanding of traffic signs is integral to driving safety. Questionnaires and behavior tests are usually used to measure sign comprehension. However,...     

低功耗便携式心电仪的设计

介绍了一种低功耗便携式心电仪的设计与实现.采用MSP430F169作为核心控制器,配有心电信号采集调理电路、液晶显示模块和数据存储模块等.该心电仪能够对心电进行实时采集处理、显示,而且可以将存储在SD卡内的数据通过USB接口在上位机上进行显示、分析,功耗低、方便携带,有较强的通用性.     

A portable,hand-powered microfluidic device for sorting of biological particles

Manually hand-powered portable microfluidic devices are cheap alternatives for point-of-care diagnostics. Currently, on-field tests are limited by the use of bulky syringe pumps, pressure controller and equipment. In this work, we present a manually operated microfluidic device incorporated with a groove-based channel. We show that the device is capable to effectively sort particles/cells by manual hand powering. First, the grooved-based channel with differently sized polystyrene particles was characterized using syringe pumps to study their distributions under various flow rate conditions. Afterward, the particle mixtures were sorted manually using hand power to verify the capability of this device. Finally, the manually operated device was used to sort platelets from peripheral blood mononuclear cells (PBMCs). The platelets were collected with a purity of ~ 100%. The purity of PBMCs was enhanced from 0.8 to 10.4% after multiple processes which results in an enrichment ratio of 13.8. During the process of manual hand pumping, the flow fluctuation caused by unstable injection will not influence the sorting performance. Due to its simplicity, this manually operated microfluidic chip is suitable for outfield settings.     

风力发电机组便携式电能质量监测系统

目前实际运行的风机只提供了显示和记录电能质量稳态数据的功能,而风机的运行特性和对电网的影响分析必须通过对其电能质量的一段时期的动态监测来获得.本文采用自主研制的双CPU架构的便携式电能质量分析仪,构建了通用的风力发电机组的动态监测系统,并用该系统对风电机组的电能质量进行了长期监测.利用监测结果进行分析和评判,可以为改进风电机组的控制策略、制定风电电能质量治理措施和确定治理装置的相关技术参数提供必要的依据.     

Early cortical processing of vection-inducing visual stimulation as measured by event-related brain potentials (ERP)

Visual motion stimuli can induce the perception of self-motion in stationary observers (known as vection). In the present study, we investigated the sensory processing underlying vection by measuring the human event-related brain potentials (ERPs) elicited by the movement onset of a visual stimulus. We presented participants a visual stimulus consisting of alternating black-and-white vertical bars that moved in horizontal direction, creating the sensation of vection. The stimulus was presented on a screen that was divided into a central and a surrounding peripheral visual area. Both areas moved independently from each other, resulting in four different movement patterns: the peripheral and the central stimulus moved in the same or opposite direction, or one of the two visual areas of the stimulus moved while the other remained stable. In addition, two different stimulus types varying with respect to the bars’ width (narrow vs. wide) were used. Participants were presented with these stimuli in two phases of the experiment: During EEG-recording, only short phases (2.5–3.5 ms) of visual motion were applied. In a separate rating phase, visual motion was presented for 45 s. In this phase, vection onset, intensity, and duration were verbally recorded. Overall, the visual stimulation generated vection with different intensities (i.e., weakest vection with sole central stimulus movement). Stimulus type did not affect vection. In the ERPs, stimulus onset elicited parieto-occipital P2 and N2 components. The amplitudes of the ERP components differed significantly between the four movement patterns (irrespective of stimulus type), however, they did not fully align with the subjective vection ratings. Since the ERPs are associated with early sensory processing preceding vection, we argue that the ERPs mirror the contribution of sensory cortical processes to vection rather than the subjective sensation of vection per se.     

矿用便携式气体检测仪无线充电装置设计

针对现有矿用便携式气体检测仪采用电池供电存在因电池容量有限、触点接触不良而影响电池的充电效果等问题,提出了一种基于无线电能传输技术的矿用便携式气体检测仪无线充电装置设计方案。无线电能发射电路将直流电能转换为高频交流电磁波信号,并通过线圈发送到空气中;无线电能接收电路通过线圈耦合空气中的电磁波信号,并通过整流滤波将其转换为直流信号,为矿用便携式气体检测仪提供电能。测试结果表明,该装置能够输出稳定的直流电压,且传输效率高。     

Operational experience with a portable friction testing device in university buildings

Following a high incidence of falls on the level recorded in a university refectory building, a more detailed examination of accident reports suggested that slippery floors in the main kitchen, serveries, dining area and corridors should be subjected to a quantitative investigation. Using a specially designed lightweight portable friction-testing device, dynamic and static coefficients of friction were measured. This enabled an assessment to be made of the ease of use and effectiveness of this portable device, in responding to accidental falls, undertaking surveys of the slip resistance of floor areas and in checking the coefficients of friction of new materials being considered as alternative floor coverings. From the results presented floor surfaces can be compared. Information was also obtained on the effect of surface projections in increasing coefficients of friction. A detailed series of measurements taken on polished woodblock floors indicated the changes during the drying of the polish, and the importance of buffing in maximizing slip resistance. The replacement of two major floor surfaces, ceramic tiles and woodblock, is examined and the friction-testing device together with recent accident statistics are used to assess the effectiveness of the new flooring materials used.