基于飞秒激光制备的光子晶体光纤Fabry-Perot温度传感器

提出并设计了一种基于飞秒激光在光子晶体光纤(photonic crystal fiber,PCF)中制备光纤法布里-珀罗(Fabry-Perot,F-P)传感器的方法。采用飞秒脉冲激光作为加工光源,结合放大倍率100×的物镜以及三维加工平台在PCF侧面采用逐线刻写方式进行加工。通过对飞秒激光光斑在光纤上的聚焦位置以及刻写功率进行优化,在PCF上刻写了深度均为80 μm、间隔为800 μm的两条划线,实现了周期为0.98 nm的全光纤F-P结构制备；实验中,对传感器在40~120 ℃温度范围内的光谱特性进行了测试与分析,每隔10 ℃进行一次数据采集,随着温度逐渐增加波长向长波方向漂移,通过对该采样点数据进行线性拟合,得到该测试点的波长温度灵敏度为9.73 pm/℃,拟合线性度为0.997。     

啮合参数对分扭-并车齿轮传动系统分岔特性的影响

为研究分扭-并车齿轮传动系统非线性分岔特性,建立了含多间隙的分扭-并车齿轮系统非线性动力学模型,引入高斯消元技术和广义相对位移变量消除了系统的刚体位移,并对动力学方程组实施了量纲一化处理。综合考虑啮合频率、齿侧间隙、综合传动误差和阻尼比等激励下的分岔通道,借助分岔图、Poincaré截面和Lyapunov指数等手段对系统的分岔行为进行了定性和定量表征。结果表明啮合频率增大时系统发生逆向倍周期分岔,分岔点位置受齿侧间隙影响显著;齿侧间隙和综合传动误差变化下混沌域内均出现短暂周期窗口;阻尼对倍周期分岔运动存在抑制作用,其结果对该类齿轮系统动力学设计具有参考价值。     

泥炭泥浆在治疗中的放射性

正为确定泥炭泥浆中天然和人工同位素的含量,并估算标准泥炭泥浆处理过程中患者皮肤吸收的辐射剂量,分析了从波兰8个矿泉采集的37个样本,用γ能谱法测量同位素浓度活性。标准泥炭泥浆浴治疗中的皮肤剂量约为300 nSv,泥炭泥浆这种治疗的有效剂量被认为是22 nSv。治疗过程中     

人工智能时代智慧警务构建机制初探

近年来,为进一步改善治安管理成效,各地区公安机关纷纷引入大数据、人工智能等技术,建设"智慧警务",同时也遇到了许多问题。本文在梳理国内智慧警务建设情况的基础上,详细分析了建设较早、成效较突出的三个典型建设案例,总结了智慧警务建设与经济的关系、常规建设步骤和创新机制,并为其它地区的智慧警务建设提出了发展建议。     

发呆,也是一种小美好

正白岩松说,没事儿的时候发发呆。我们疲于追逐成功的路上,发呆成了一种奢侈。是啊,回想一下,在我们每天仅有的24小时中,工作、交际以及各种琐事占据了大半,剩下的注意力又被手机等携带大量娱乐信息的产品夺走。我们每天生活的似乎都很"丰满",迈着急促的脚步穿梭于公司、学校、商场、电影院之间,甚至感觉时间不够用,经常熬夜到凌晨,因此,我们没有多余的时间去发呆,或者说,在这个充满娱乐信息的时代,我们不需要去孤独地发呆。     

一种利用表冷器分置温湿分控节能改造方案

某夏热冬冷地区卷烟厂空调机组除湿工况时系统能耗最大,采用一次回风需要大量的再热能量。基于热湿独立处理的理念及烟厂现有设备改造工程量,提出了表冷器分置、热湿分控方案。并根据烟厂所在城市的气候特征,分析了改造方案的节能潜力,发现可节能25%的制冷量和31.5%的再热能耗。在分析的基础上,对卷烟厂空调机组进行了改造,并连续监测了除湿工况季(5月15日～6月16日)的耗能,通过每隔24小时切换一次新老系统并测试能耗,发现改造后的系统冷冻水制冷量和蒸汽节能量分别节约了21%和29%,节能效果显著。表冷器分置、温度分控方案具有巨大的节能改造潜力。     

An assessment of natural concentrations of selected metals in the bone tissues of the femur head

The study was aimed at assessing the natural concentrations of copper, iron, potassium, lead and cadmium in the femur head using regression analysis. The material was collected during the operation of total hip arthroplasty from patients of southern and central Poland suffering from diagnosed coxarthrosis. In total, 197 samples were collected, including 68 samples of spongious bone, 59 samples of cortical bone and 70 samples of cartilage surface. After wet microwave digestion, the metal content in the samples was measured by atomic absorption spectrophotometry. The average concentrations of metals in the femur head were 67.30 microgFe/g, 760.58 microgK/g, 0.07 microgCd/g, 0.81 microgCu/g and 2.76 microgPb/g. A comparison of metal concentrations in bone tissues assessed by regression analysis to the findings of other authors revealed that the technique can be used to assess the natural concentration of elements in tissues and the results may provide a basis for the evaluation of metal concentrations in the human organism.     

Land inputs of trace metals, major elements, particulate organic carbon and suspended solids to an industrial coastal bay of the NE Atlantic

Rivers, streams and municipal and industrial effluents flowing into the Ferrol Ria (NW Spain) were analyzed for dissolved and particulate trace elements (Cd, Cu, Pb, Zn), particulate major elements (Al, Fe, Si), particulate organic carbon and nitrogen (POC and PON), and total suspended solids. Trace metal clean techniques were applied. Mean annual fluxes of these components were calculated. Dissolved trace metal concentrations in the major freshwater inputs were found to be within typical values for uncontaminated rivers: Cd: 0.020-0.035 nM; Cu: 11.7-19.2 nM; Pb: 0.40-0.71 nM and Zn: 18-54 nM. Two sources of suspended particulate matter (SPM) were observed: (i) a detrital SPM, which becomes more important at high river discharges, with metal concentrations tending to lithogenic values; (ii) an organic- and metal-rich SPM, which becomes dominant at low discharges. Municipal and industrial effluents in the northern shore, despite of constitute a minor freshwater contribution to the bay, were responsible for more than 50% of total inputs of Cu, Cd, Pb, Zn, POC and PON. The fluxes of trace metals obtained for the Ferrol Ria are in the range of other inhabited world semi-enclosed embayments.     

Assessment of DNA damage in coal open-cast mining workers using the cytokinesis-blocked micronucleus test and the comet assay

Coal mining is one of the most important causes of environmental pollution, as large quantities of coal dust particles are emitted. Colombia-South America has large natural coal reserves and “El Cerrejón” is the world's largest open-cast mine located in the northern department of Guajira. The aim of the present study was to evaluate genotoxic effects in a population exposed to coal residues from the open-cast mine “El Cerrejón”. 100 exposed workers and 100 non-exposed control individuals were included in this study. The exposed group was divided according to different mining area activities: (i). Transport of extracted coal, (ii). Equipment field maintenance, (iii). Coal stripping and, (iv). Coal embarking. Blood samples were taken to investigate biomarkers of genotoxicity, specifically, primary DNA damage as damage index (DI), tail length and% of tail DNA using the Comet assay (alkaline version) and chromosome damage as micronucleus (MN) frequency in lymphocytes. Both biomarkers showed statistically significantly higher values in the exposed group compared to the non-exposed control group. No difference was observed between the exposed groups executing different mining activities. These results indicate that exposure to coal mining residues may result in an increased genotoxic exposure in coal mining workers. We did not find a correlation between age, alcohol consumption and service time with the biomarkers of genotoxicity. Our results are the first data of genotoxic effects induced by coal mining exposure in Colombia, and thus, contribute to the exploration of test batteries use for monitoring of exposed populations and may stimulate designing control, hygiene and prevention strategies for occupational health risk assessment in developing countries.