Geothermal assessment of the deep aquifers of the northwestern part of the Bohemian Cretaceous basin, Czech Republic

Groundwater in the Benešov-Ústí aquifer system in the northwestern Bohemian Cretaceous basin has been intensely exploited since the twentieth century. Apart from providing drinking water, it contains the most extensive accumulation of thermal water in the country. However, excessive exploitation can result in temperature declines and changes in the quality of the groundwater in the future. More than a hundred in situ temperature measurements were used to assess the geothermal gradient and heat flux. However, intense groundwater vertical flow across the well significantly controls the heat flux distribution, resulting in a huge range of values—from less than 50 mW/m² within infiltration areas to more than 125 mW/m² in drainage areas. Certain simplifications and corrections considering the vertical flow between different permeable zones were developed, and the correction for topography as well as lithological variability have been applied to improve accuracy of the geothermal gradient assessment. Despite the fact that the Bohemian Cretaceous basin is tectonically very complex, it is concluded that tectonics [with the exception of the Eger (Oh?e) rift] has only a secondary effect on the thermal field. Two longitudinal W-E areas in the Benešov-Ústí aquifer system have elevated heat flux values. The calculated heat flux values are useful for heat transfer modelling and the assessment of the sustainable limits of thermal water exploitation.     

Thermometry of red nanoflaked SrAl12O19:Mn4+ synthesized with boric acid flux

This paper presents the luminescence properties and potential of red SrAl₁₂O₁₉:Mn⁴⁺ (SAO:Mn⁴⁺) phosphor for optical thermometry application. The SAO crystal consisted of a spinel block along with two mirror-like blocks. The Al³⁺/Sr²⁺ molar ratio of the precursor solution affected the crystalline-phases, morphology, and photoluminescence of the phosphor. The addition of flux H₃BO₃ promoted the growth of hexagonal-nanoflakes and enhanced the external quantum efficiency of phosphor 2.6-fold. The absolute sensitivity S_a and relative sensitivity S_r of SAO:Mn⁴⁺ showed a linear function of the temperature. The value of S_a was 4.17?×?10^?3 K^?1, and the maximum S_r was 2.70?×?10^?3 K^?1 at 393?K. A stable emission color was observed even with a change in temperature and a bright red light was seen in both daylight and a darkroom.     

Large eddy simulations and rotational CARS/PIV/PLIF measurements of a lean premixed low swirl stabilized flame

This paper reports on numerical and experimental studies of a lean premixed low swirl stabilized methane/air flame. The burner is made up of a central perforated plate and an annular swirler. A premixed methane/air mixture at an equivalence ratio of 0.62 is injected to an ambient co-flow of air through the burner under atmospheric pressure and room temperature condition with a Reynolds number of 30,000. Stereoscopic Particle Image Velocimetry (PIV) and simultaneous OH/acetone Planar Laser Induced Fluorescence (PLIF) are used to characterize the flame front and the turbulence field downstream of the burner. The flame is stabilized in the low speed central region and in the inner shear-layer vortices, where ambient air dilution to the flame is found to eventually quench the reactions downstream. Rotational Coherent Anti-Stokes Raman Spectroscopy (RCARS) measurements are carried out to characterize the temperature field and the relative oxygen mole fraction field, which enables quantification of the air dilution to the flame. The experimental data provides a challenging test case for numerical simulation models owing to the stratification of the mixture and quenching of the flame. Large eddy simulations are carried out using a three-scalar level-set G-equation flamelet model, which is shown to capture the basic flame characteristics and quenching at the trailing edge of the flame.     

Optical thermometry based on near-infrared luminescence from phosphors mixture

Luminescence ratiometric thermometry based on rare earth(RE)ions has attracted great interest for the potential applications in many fields.But the improvement of the measurement sensitivity and accuracy is significantly restricted due to the small energy gap between thermally coupled levels(TCL).Here,a strategy striving for good thermometric properties of luminescent materials was designed by using the phosphors mixture composed of NaY(WO₄)₂:Nd³⁺-Yb³⁺and NaY(WO₄)₂:Er³⁺,which were prepared by secondary sintering method.Under the excitation of 980 nm lase r,the near-infrared(NIR)emissions(710-920 nm)from Nd³⁺ions are effectively strengthened when the temperature increases from 304 to773 K,whereas Er³⁺NIR luminescence centered at around 1536 nm is thermally quenched.The remarkably different response of NIR emissions to the thermal variation allows us to map temperature through the ratiometric method.By optimizing the dopant concentration of rare earth(RE)ions,a maximum sensitivity of 5.14%/K together with a measurement uncertainty of about 0.1 K is acquired at304 K,which is superior to the previously reported RE luminescence-based temperature sensors,indicating that the approach developed here can pave the way for achieving optical thermometry with desired properties.     

一种主从式微机红外测温系统

本文提出一种针对机车模拟加载测试台的微机红外测温系统，该系统以热电堆红外传感器件作为主要的温度探测器件，由单片机８０３１集总采集，通过串行通信与ＰＣ机构成主从式控制系统，从而可实现温度和包括其它信息参数在内的远程自动检测或故障诊断。文章讨论和介绍了这一系统的具体设计。     

Thermal microscopy of electronic materials

Due to an increasing level of device integration and progressive device miniaturization, the thermal management requires comprehensive microscopic investigations of thermal properties as heat dissipation on the micro- and nanoscale. Today heat management is one of the key limiting factors in a wide range of electronic applications, e.g. in automotive and electro-mobility. In this review, an overview on far-field and near-field thermal microscopy techniques using infrared thermography, laser beam techniques, and scanning probe microscopy is given. The common aim of all these approaches is to get access to temperature distributions, heat transport mechanisms, thermos-elastic quantities, as well as thermoelectric properties of electronic materials on microscopic levels. Examples for devices inspections, for integrated circuit analysis, and for thin film technology applications at micro and nanoscale are presented.     

Development of the Sealed-Type Triple-Point-of-Argon Cell for Long-Stem SPRT Calibration at KRISS

A system was fabricated to realize the triple point of argon for the calibration of long-stem standard platinum resistance thermometers. A cryostat was constructed so that the temperature could be controlled quasi-adiabatically, and the melting was realized using the continuous-heating method. The combined uncertainty of the realization of the triple point of argon for a confidence level of 95% was 0.6 mK.     

三维火焰温度场光纤传感器设计

传统三维火焰温度场无损测量主要利用全息干涉方法或莫尔光栅方法，这些方法存在着测量系统复杂、成本高、数据获取困难等缺点。设计出一种基于多光谱辐射层析测温原理的三维光纤温度传感系统，系统具有使用灵活，测量精度高，获得数据便捷等优点。采用重排算法及MART技术相结合作为少投影数扇形束CT重建算法。四峰温度场模型的重建结果为确定光纤温度传感器旋转及扫描参数提供了依据。     

White OLED based on a temperature sensitive Eu3+/Tb3+ β-diketonate complex

A mixed lanthanide β-diketonate complex of molecular formula [Eu_0.45Tb_0.55(btfa)₃(4,4′-bpy)(EtOH)] (btfa^– = 4,4,4–trifluoro–1–phenyl–1,3–butanedionate; 4,4′-bpy = 4,4′-dipyridyl; EtOH = ethanol) was synthesized and its structure was elucidated by single crystal X-ray diffraction. The temperature dependence of the complex emission intensity between 11 and 298 K is illustrated by the Commission Internacionale l’Éclairage (CIE) (x, y) color coordinates change within the orange-red region, from (0.521, 0.443) to (0.658, 0.335). The existence of Tb³⁺-to-Eu³⁺ energy transfer was observed at room temperature and as the complex presents a relatively high emission quantum yield (0.34 ± 0.03) it was doped in a 4,4′-bis(carbazol-9-yl)biphenyl (CBP) organic matrix to be used as emitting layer to fabricate a white organic light-emitting diode (WOLED). Continuous electroluminescence emission was obtained varying the applied bias voltage showing a wide emission band from 400 to 700 nm. The white emission results from a combined action between the Eu³⁺ and Tb³⁺ peaks from the mixed Eu³⁺/Tb³⁺ complex and the other organic layers forming the device. The intensity ratio of the peaks is determined by the layer thickness and by the bias voltage applied to the OLED, allowing us to obtain a color tunable light source.     

NMIA Realization of the ITS-90 Based on Fixed-Point Cell Ensembles

NMIA has recently moved from an ITS-90 realization based on single cells of each fixed point to one based on ensembles of up to five cells of each fixed point from argon to silver. It has been suggested that relying on Raoult’s law to estimate the concentration of impurities in fixed-point cells, and to thereby estimate the likely shift introduced to the temperature of the melting or freezing phase transition, is inadequate. Measurements of NMIA’s present set of 36 cells confirm that using Raoult’s law alone is inadequate, and underestimates the temperature depression of some cells. Material purity assays are usually available for the metals (or gases); however, this will not include contamination introduced during the cell construction process or in-use impurity migration into the sample. At NMIA, we have (1) established ensembles of up to five cells of each fixed point and (2) established techniques and uncertainties for comparisons of cells at the 0.2 mK level. It is concluded that, at the sub-mK accuracy level, fixed-point cells should be considered as artifacts requiring calibration or validation to confirm their suitability as intrinsic reference standards.