Cardiac autonomic dysfunction in hemodialysis patients: The value of heart rate turbulence

Patients with end-stage renal disease (ESRD) are likely to have cardiac autonomic dysfunction, which is related with an increased risk of sudden death. The aim of this study is to detect cardiac autonomic dysfunction in patients with ESRD and to evaluate the possible acute effects of hemodialysis (HD) on cardiac autonomic functions measured by heart rate variability (HRV) and heart rate turbulence (HRT). Thirty-one (mean age 50 ± 13 years, 15 males) with ESRD on regular HD program and 31 healthy volunteers (mean age 51 ± 12 years, 15 males) were included in the study. Twenty-four-hour ambulatory electrocardiogram recordings were taken from the subjects before and after HD and from the control group. Heart rate variability and HRT parameters were calculated from these recordings. All of the HRV and HRT parameters were found to be significantly blunted in patients in comparison with healthy individuals. There were significant differences in HRV after HD, but similar differences were not observed in HRT parameters. Cardiac autonomic functions were significantly altered in patients with ESRD. Heart rate turbulence parameters seemed to be less affected from HD and may be more useful in the evaluation of cardiac autonomic functions in the ESRD population.     

Case study: performance effectiveness and cost-benefit analyses of open-graded friction course pavements in Tennessee

The effectiveness and cost-benefit of Open-Graded Friction Course (OGFC) pavements were analysed in this study by investigating the cost, field performance, short- and long-term effectiveness, and accident rate of OGFC projects in Tennessee. Paired sample t-tests were conducted to compare if there was significant difference between OGFC and non-OGFC sections. Investigation on the performance effectiveness showed that OGFC sections provided comparable performance level as traditional dense mix overlays and were effective in improving pavement performance and repairing deterioration except for rutting potential. However, no severe pavement deterioration was observed on the OGFC sections after more than four or five years of service, indicating sufficient durability of the OGFC used in Tennessee where mild freeze-thaw cycles are experienced annually. Although the unit cost ($/m³) of OGFC was about 42% higher than the cost of traditional dense mix overlays, it was observed that the accident rate was significantly reduced especially in rainy days after the OGFC treatment. The cost-benefit analyses based on the ratio of accident rate reduction over cost demonstrated that OGFC was significantly more cost-beneficial in improving driving safety and reducing accident rate in rainy days.     

基于多因素噪声模糊综合评价方法的研究及应用

以往的噪声评价是基于A声级进行的,缺乏对人的心理和除听力以外的其它生理因素的考虑。因此,文章在传统的噪声评价研究的基础上,建立具有创新意义的由听力损失、心率变异和脑波组成的多因素噪声模糊评价系统,进行噪声对人体负荷综合影响的评价。经过标准噪声人机实验的验证分析,得到结论：多因素的评价方法较传统方法更符合实际影响情况。     

心率变异性在手控交会对接操作脑力负荷评价中的应用

目的研究心率变异性指标用于脑力负荷评价的可行性,并对其在手控交会对接脑力负荷评价中的应用进行分析讨论。方法实验研究以手控交会对接操作为主任务,使用心率变异性来表征脑力负荷水平的变化。对8名志愿者进行了两个阶段共6轮的训练,每轮训练由10个共包含了高、中、低难度水平的操作单元组成。通过比较志愿者在两个阶段的关键绩效指标和心率变异性指标,分析心率变异性指标用于脑力负荷评价的有效性。结果在不同的操作难度、训练程度和操作阶段之间,部分心率变异性指标表现出了较强的敏感性,随着训练程度和操作阶段的变化,其敏感性强度也存在一定的差异。结论实验结果表明心率变异性指标可以用于脑力负荷评价,随着训练程度的提高,脑力负荷水平逐渐降低;随着单次操作过程中由前到后的变化,脑力负荷水平逐渐降低。     

吸附式制冷工质对的吸附性能测试研究

吸附剂的性能是吸附制冷技术中最重要的参数之一,而吸附量和吸附速率是吸附剂性能的2个重要指标。准确测定吸附剂的性能对于吸附制冷机的设计起着至关重要的作用。本文结合国内外对吸附剂性能的测试方法以及本课题对汽车余热吸附制冷所用吸附剂的性能进行测试,着重阐述吸附剂性能测试所用方法的特点以及使用范围,旨在为吸附剂性能的准确测试提供参考。     

Approximate design and performance of the robust control charts for monitoring dispersion in Phase I

This article designs and studies the approximate performance of robust dispersion charts, namely, MAD chart, S_n chart, and Q_n chart, in Phase I analysis (recently developed in the literature). The proposed limits are based on false alarm probability for monitoring the dispersion of a process in Phase I analysis. The charting constants are determined to achieve the required nominal FAP (FAP₀). The performance of these structures is evaluated in (i) the attained false alarm rate and (ii) the probability of signals for out‐of‐control situations. The analysis shows that the proposed design of Phase I robust dispersion charts correctly controls the FAP and shows a good performance in detecting the shifts in the process variation. An illustrative example is used to explain the practical implementation of these limits.     

波阻抗对岩石动力学特性影响的模拟试验研究

利用分离式霍普金森压杆(SHPB)试验系统,对系列波阻抗的模型材料进行不同应变率下的冲击压缩试验。试验结果表明:岩石在冲击荷载下的应力波传播特征、动态应力应变关系以及破碎块度分形特征同时受波阻抗、应变率和冲击速度的影响。波阻抗相同时,反射波和透射波信号幅值均随冲击速度增大呈线性增大,同时应变率效应明显,随着应变率的增大:峰值应力呈线性增大,动态弹性模量增大,应变软化阶段延长;破碎程度增大,破碎块度分形维数呈线性增大。应变率相同时,随着波阻抗的减小:反射波幅值增大、透射波幅值减小;峰值应力减小,应变软化阶段延长,塑性段趋于明显,且有塑性流动现象出现;破碎程度增大,破碎块度分形维数增大。同时随着波阻抗减小,应变率增大对动态抗压强度的增大以及对破碎程度的加剧效果减弱,应变率效应减弱,逐渐趋于不明显。     

Bending impact on the performance of a flexible Li4Ti5O12-based all-solid-state thin-film battery

The growing demand of flexible electronic devices is increasing the requirements of their power sources. The effect of bending in thin-film batteries is still not well understood. Here, we successfully developed a high active area flexible all-solid-state battery as a model system that consists of thin-film layers of Li₄Ti₅O₁₂, LiPON, and Lithium deposited on a novel flexible ceramic substrate. A systematic study on the bending state and performance of the battery is presented. The battery withstands bending radii of at least 14 mm achieving 70% of the theoretical capacity. Here, we reveal that convex bending has a positive effect on battery capacity showing an average increase of 5.5%, whereas concave bending decreases the capacity by 4% in contrast with recent studies. We show that the change in capacity upon bending may well be associated to the Li-ion diffusion kinetic change through the electrode when different external forces are applied. Finally, an encapsulation scheme is presented allowing sufficient bending of the device and operation for at least 500 cycles in air. The results are meant to improve the understanding of the phenomena present in thin-film batteries while undergoing bending rather than showing improvements in battery performance and lifetime.