爆破位置对深凹露天矿山炮烟扩散的影响研究

深凹露天矿山由于其特殊的结构,爆破产生的炮烟扩散稀释较为困难,严重危害生产作业人员的生命安全与健康。基于实际矿山构建了深凹露天矿山的二维物理及数学模型,采用非稳态数值分析方法研究了不同爆破位置下,深凹露天矿山采坑内爆破炮烟的扩散规律。研究结果表明：不同爆破位置下,露天采坑内均出现复环流,爆破点位置是影响露天采坑内风流结构特征的重要因素；露天采坑内的炮烟最高浓度均随着时间变化而逐渐下降,但下降的速率逐步减小,呈现三个阶段的下降趋势；爆破位置位于背风侧时露天采坑内的炮烟最高浓度和降至安全浓度所需时间远高于迎风侧三个爆破位置；随着背风侧爆破点距采坑底部距离的减小,炮烟最高浓度及降至安全浓度所需时间先降低后增加,炮烟最高浓度及降至安全浓度所需时间随着迎风侧爆破位置距采坑底部距离的减小而增加。研究结果对于指导深凹露天矿山企业合理组织爆破后的生产作业和保障作业人员安全具有重要意义。     

Italian translation,validation, and repeatability of Standard Patient Evaluation of Eye Dryness (SPEED) Questionnaire

PurposeThe assessment of symptoms of dry eye disease using a questionnaire is an effective and simple method of quantifying symptoms. The aim of this study was to translate the SPEED questionnaire and adapt it for the Italian language and verify the main psychometric performance of the translated version, including repeatability and agreement.MethodsThe SPEED questionnaire was translated into Italian following a standard methodology. The resulting questionnaire was administered to 206 adult participants in order to perform a validation analysis. A subgroup of 82 participants was retested after one week to give a repeatability and agreement assessment.ResultsInternal consistency showed an alpha of 0.852 (95% CI 0.818–0.881) and no unnecessary items. The factor analysis showed a saturation for three main factors related to (i) Dryness and Soreness, (ii) Fatigue, and (iii) Burning. Repeatability was high, with a CCC of 0.896 (95% CI 0.844–0.931). Agreement analysis showed no significant bias between sessions and an interval of agreement of 5 points for SPEED score.ConclusionThe translation and adaptation of the SPEED questionnaire for the Italian language have demonstrated good psychometric properties for the translated questionnaire, confirming and expanding the original psychometric characteristics. Consequently, the SPEED questionnaire could be used to measure the presence of symptoms of dry eye quantitatively.     

Influence of temperature on acoustic emission source location accuracy in underground structure

An acoustic emission (AE) experiment was carried out to explore the AE location accuracy influenced by temperature. A hollow hemispherical specimen was used to simulate common underground structures. In the process of heating with the flame, the pulse signal of constant frequency was stimulated as an AE source. Then AE signals received by each sensor were collected and used for comparing localization accuracy at different temperatures. Results show that location errors of AE keep the same phenomenon in the early and middle heating stages. In the later stage of heating, location errors of AE increase sharply due to the appearance of cracks. This provides some beneficial suggestions on decreasing location errors of structural cracks caused by temperature and improves the ability of underground structure disaster prevention and control.     

非径向管板焊接接头的超声检测

对AP1000压水堆核电站安全壳贯穿件的非径向管板焊接接头结构特点进行了介绍,并分析其超声检测工艺的重点和难点。通过建立统一的缺陷定位坐标系并结合被检构件的几何特点进行综合分析,推导得出了h值(缺陷回波最高点距套管外壁的距离)的计算方法。为超声检测对这类焊接接头缺陷的准确识别和定位提供了行之有效的方法,为解决这类焊接接头的超声检测技术受限区提供了行之有效的措施。     

发用类、肤用清洁类化妆品的急性皮肤和眼刺激损害特点

分析发用类、肤用清洁类化妆品的急性皮肤刺激和急性眼刺激损害特点,了解其卫生安全状况。于2012年采用《化妆品卫生规范》(2007年版)中的急性皮肤刺激性实验和急性眼刺激性实验对发用类、肤用清洁类共计158种化妆品样品进行测试。两类受试化妆品显示出不同程度的急性皮肤刺激性和急性眼刺激性损害效应。发用类化妆品在实验中基本无皮肤刺激性损伤;肤用清洁类化妆品在实验中有少量的皮肤刺激性损伤,但大都为轻刺激性(31.0%),只有个别(3.8%)出现了皮肤红斑水肿的中刺激性损伤。发用类、肤用清洁类化妆品在急性眼刺激性实验中检出一定比例具有微刺激性及以上刺激性的样品,但引起的眼损伤都能够在观察期限内恢复。本次调查的所有化妆品中,洁面类、洗发类化妆品普遍具有急性眼刺激性和急性皮肤刺激性损害,需加强对化妆品的监督管理,进一步提升化妆品卫生安全水平,保障化妆品使用安全。     

面向连续查询的敏感语义位置隐私保护方案

针对连续查询位置服务中构造匿名区域未考虑语义位置信息导致敏感隐私泄露问题，通过设计[(K,θ)]-隐私模型，提出一种路网环境下面向连续查询的敏感语义位置隐私保护方案。该方案利用Voronoi图将城市路网预先划分为独立的Voronoi单元，依据用户的移动路径和移动速度，选择具有相似特性的其他[K-1]个用户，构建匿名用户集；利用匿名用户集用户设定的敏感语义位置类型和语义安全阈值，以及用户所处语义位置的Voronoi单元，构建满足[(K,θ)]-隐私模型的语义安全匿名区域，可以同时防止连续查询追踪攻击和语义推断攻击。实验结果表明，与SCPA算法相比，该方案在隐私保护程度上提升约15%，系统开销上降低约20%。     

Differences between oculomotor and perceptual artifacts for temporally limited head mounted displays

We used perceptual and oculomotor measures to understand the negative impacts of low (phantom array) and high (motion blur) duty cycles with a high‐speed, AR‐likehead‐mounted display prototype. We observed large intersubject variability for the detection of phantom array artifacts but a highly consistent and systematic effect on saccadic eye movement targeting during low duty cycle presentations. This adverse effect on saccade endpoints was also related to an increased error rate in a perceptual discrimination task, showing a direct effect of display duty cycle on the perceptual quality. For high duty cycles, the probability of detecting motion blur increased during head movements, and this effect was elevated at lower refresh rates. We did not find an impact of the temporal display characteristics on compensatory eye movements during head motion (e.g., VOR). Together, our results allow us to quantify the tradeoff of different negative spatiotemporal impacts of user movements and make subsequent recommendations for optimized temporal HMD parameters.     

基于声源定位的高校在线巡课系统设计与研究

随着网络建设以及信息化教学方法在高校教学过程中的应用普及,越来越多的高校使用在线巡课系统对教师的教学过程进行跟踪和管理,以便发现课堂教学中的亮点、问题和不足。文章提出的在线巡课系统,基于声源定位的技术,对传统的在线巡课系统做出了改进,解决了已有巡课系统中“只闻其声,不见其人”的问题,能够更直观地跟踪到教师的教学过程,包括教学行为以及师生互动过程,有效提升教务人员巡课效果和体验感受。     

基于伪布尔模型和启发式算法求解无容量设施选址问题

采用伪布尔模型和启发式算法来求解无容量设施选址问题。首先给出了问题的伪布尔(pseudo-Boolean)表示，然后基于Khumawala规则对问题进行预处理，最后提出两种启发式分支准则来求解问题。实验结果表明所提算法简单有效。     

Changes in accommodative micro-fluctuations after wearing contact lenses of different optical designs

PurposeAccommodative micro-fluctuations (AMF) are small dioptric changes during accommodation. The aim of this study was to evaluate and compare changes in AMF when wearing silicone hydrogel contact lenses of two different optical designs.MethodsA multi-centre, randomised, cross-over, non-dispensing study was conducted on 68 adapted contact lens wearers aged 25–35 years to compare AMF responses to a spherical and aspheric silicone hydrogel (comfilcon A) lens designs. A Righton Speedy “i” series Auto Refractometer in accommodation analyser mode was utilized before and after reading a standard text in font size 8 on an iPhone 5 for 20 min at a 25 cm viewing distance. Phone screen brightness was set by automatic adjustment mode and ambient illumination was controlled at all sites.ResultsMean ± SD AMF change from before to after the reading task was 2.25 ± 5.6 and 0.13 ± 5.7 (relative values) for the spherical and aspheric lens designs, respectively. The difference was statistically significant (P = 0.017, Paired t-test).ConclusionsThe smaller change in AMF when using an aspheric lens design suggests reduced ciliary muscle stress when reading print on a smart phone at a close distance for short periods (20 min). Contact lens wearers who frequently use digital devices and are experiencing eye strain may benefit from switching from a spherical design to one that incorporates aspheric optics.