Cooperative Tracking Using Multiple PTZ Thermal Imagers

A cooperative object tracking framework is proposed which shifts the priority of tracking by pose estimation based on registration between fields of view (FOVs) of different pan?Ctilt?Czoom (PTZ) thermal imagers, avoiding transferring the local features from one imager to another. When an object is selected for tracking, the related PTZ thermal imager tracks it using an improved particle filtering method, and estimates the pose of the imager simultaneously. Once the object enters an overlapping FOV of two imagers, the handoff thermal imager is activated immediately according to the spatial relationship built by pose estimation, and turns to tacking and pose estimation status. Meanwhile, the previous camera returns to waiting status for reactivation. Experiments are conducted to show the proposed framework is applicable to cooperative object tracking for PTZ thermal infrared imagers.     

Thermal Image Degradation Through a Heated Sapphire Window

Optical windows are indispensable for monitoring industrial processes under vacuum or high pressure by using thermal imagers and radiation thermometers. When a thermal imager observes a sample through an infrared window at elevated temperatures, the window emits additional thermal radiation and increases the background signal of the thermal images, which results in image degradation. Standard four-bar images with various radiance temperature differences were measured using a thermal imager with a spectral band from 3 ??m to 5 ??m through a UV-grade sapphire window. The four-bar images are given by a blackbody collimator with various image patterns. The window was indirectly heated in a furnace and then rapidly placed on the optical path between the collimator and the thermal imager. The four-bar image degradation was measured as a function of the window temperature and the radiance temperature difference of the four-bar pattern. A simple equation which describes the contrast of the four-bar image by using the transmittance and reflectance of the sapphire window was proposed. It was confirmed that the model can properly predict the window temperature when the appearance of the four-bar pattern cannot be determined.     

A Critical Look at Type T Thermocouples in Low-Temperature Measurement Applications

Type T thermocouples are commonly used in industrial measurement applications due to their accuracy relative to other thermocouple types, low cost, and the ready availability of measurement equipment. Type T thermocouples are very effective when used in differential measurements, as there is no cold junction compensation necessary for the connections to the measurement equipment. Type T’s published accuracy specifications result in its frequent use in low-temperature applications. An examination of over 250 samples from a number of manufacturers has been completed for this investigation. Samples were compared to a standard platinum resistance thermometer (SPRT) at the LN2 boiling point along with four other standardized measurement points using a characterized ice point reference, low-thermal EMF scanner, and an 8.5 digit multimeter, and the data were compiled and analyzed. The test points were approximately ?196 °C, ?75 °C, 0 °C, + 100 °C, and + 200 °C. These data show an anomaly in the conformance to the reference functions where the reference functions meet at zero. Additionally, in the temperature region between ?100 °C and ?200 °C, a positive offset of up to 5.4 °C exists between the reference function equations published in the United States in ASTM E230-06 for the nitrogen point and the measured response of the actual wire. This paper also examines the historical and technological reasons for this anomaly in the US reference function. The study concludes that Type T thermocouples typically do not conform to the ASTM E230-06 published reference function describing their performance when used to measure temperature in the range of ?100 °C to ?200 °C.     

Design and Validation of the MBW Standard Humidity Generators

MBW Calibration AG (MBW) is the Designated Institute (DI) for humidity appointed by the Federal Institute of Metrology, METAS. MBW currently offers calibration and measurement capabilities (CMC) for frost/dew-point hygrometers by comparison with precision chilled-mirror transfer standards that have been calibrated using the primary standards of leading European National Metrology Institutes or DI. The design, construction and validation of two standard humidity generators to be used as the Swiss national standards for the primary realization of frost/dew-point temperature in the range from ? 90 °C to + 95 °C are presented and discussed. The generators are operated as continuous flow “single-pressure” generators in the range from ? 80 °C to ? 10 °C with saturation over ice and from 0.5 °C to + 95 °C with saturation over water. Additionally, they are used in “two-pressure” mode for saturation over ice down to frost-point temperatures of ? 90 °C and down to ? 20 °C for saturation over water. The main saturators of both generators have been designed to fit in commercially available calibration baths with either ethanol or distilled water as the heat transfer fluid for saturator temperatures below and above 0 °C, respectively. Saturator temperature is measured using standard platinum resistance thermometers and a purpose-built precision thermometer. Pressure measurements are taken with gauge pressure transducers and a separate barometric sensor, to reduce the influence of the atmospheric pressure on the measurement of the pressure ratio and make full use of the correlation of pressure measurements and enhancement factors when operating in two-pressure mode. A totally automated pre-saturation and flow control system facilitates the calibration of state-of-the-art chilled-mirror transfer for standards without manual readjustment of the generated flowrate to ensure a constant volumetric flow at the conditions of the mirror. The uncertainty budget leading to the CMC for frost/dew-point temperature realization is presented in the context of the experimental validation performed. The results in the overlapping range of both generators are presented and used as further evidence of the saturation efficiency of both standards.     

Investigating Temperature Distribution of Two Different Types of Blackbody Sources Using Infrared Pyrometry Techniques

A comparison between two different types of thermal radiation sources maintaining near blackbody conditions has been carried out in the range from 50 to 500 °C. An infrared total radiation pyrometer was used as a transfer standard to measure the temperature of blackbodies. A thorough study of temperature distribution has been carried out for the large surface source in order to characterize the best location over the surface blackbody for temperature determination precisely of the order of better than 0.1 °C. The expanded uncertainty in the estimation of temperature of the radiating source in the above range of measurement was evaluated to be within ±0.24 °C at 50 °C and ±0.88 °C at 500 °C. The blackbody temperature sources found to be suitable for calibration of infrared total radiation pyrometers and thermal imaging devices in the operational range as mentioned above for laboratory use or other industrial and medical applications.     

Experimental study of thermal expansion of hardened cement paste

Thermal expansion of hardened cement paste has been determined within the temperature range of ?30°C and +80°C. Mositure content varied from virtually zero to saturaton. Immediate thermal response is followed by time dependnt ration. Immediate thermal response is followed by time dependent partial recovery. A tentative explanation for this behaviour is given.     

High-temperature phase transition,coordination mechanism and magnetism in multiferroic YMnO<Subscript>3</Subscript> nanopowders

Single phase YMnO₃ nanopowders were successfully synthesized by a modified polyacrylamide gel route at an optimal sintering temperature. High temperature is helpful for further crystallization and the formation of single hexagonal YMnO₃. The process was monitored by X-ray diffraction as well as by X-ray photoelectron spectroscopy, transmission electron microscope, Fourier transform infrared spectrum and magnetic measurements. A mixture of orthorhombic and hexagonal phases was found to exist in the 800?°C, while for the metastable orthorhombic YMnO₃ phase complete conversion to hexagonal phase occurs at 950?°C. In the synthesis process, the coordination mechanisms of EDTA anions and metal ions (Y³⁺ and Mn³⁺) have been discussed on the basis of the experimental and computational results. The synthesis route used in this case has been aggreed to be more convenient for obtaining single hexagonal YMnO₃ phase than by the combination of hydrothermal synthesisand additional thermal treatment or the glycine–nitrate process. The magnetic susceptibility indicates that the anti-ferromagnetic transition temperature increases from 58 to 71 K with increasing sintering temperature from 800 to 950?°C.     

Performance characteristics of an apparatus based on the curve-fitting method for measuring thermal properties at cryogenic temperatures

This paper describes the performance characteristics of a new test apparatus and the measured results using the apparatus. It has been developed on the basis of Harmathy's curve-fitting method to measure, in a short time, the physical properties of the nonmetallic materials for a cryogenic storage tank. The apparatus has been used to measure the heat capacity, thermal conductivity, and thermal diffusivity of the materials at the same time in the temperature range of approximately ?180°C to +50°C.With this apparatus the thermal conductivity can be measured over a wide range of approximately 0.01 kcal m^?1 h^?1°C^?1 to 10 kcal m^?1 h^?1°C^?1 in the range of ?180°C to +50°C. The materials investigated were structural materials such as concrete, wood, frozen soil, and autoclaved lightweight concrete (ALC) and such insulation materials as calcium silicate, phenolic foam, and polyurethane foam.     

Enhanced optoelectronic,thermal, mechanical and third order nonlinear optical properties of dichlorobis(thiourea)zinc(II) crystal: an effect of Phenol red dye

For the first time the growth of dichlorobis (thiourea) zinc(II) (ZTC) monocrystal in presence of Phenol red dye of considerably good size (~13 mm?×?5 mm) has been achieved from aqueous solution using slow evaporation solution technique at room temperature. The solubility was calculated at different temperatures. The crystal structure was confirmed through X-ray diffraction analysis. The crystallinity of the dyed crystals has been enhanced revealed by Powder X-ray diffraction study. The presence of dye was inveterate by FT-IR and FT-Raman spectroscopic studies. The scanning electron microscopy analyses show that the grown crystals with dye are better than pure. Diffused reflectance was measured and optical band gap was calculated found to be enhanced from 4.5 to 4.65 eV for dyed crystals. The enhancement in the PL intensity has been observed in the dyed crystals. DSC study shows that the thermal stability has been remarkably enhanced from 163?°C (pure) to 203?°C (dyed) and various other thermal parameters are calculated. The surface study shows that the grown crystals with dye possess less dislocation than pure. Mechanical strength of the dyed crystal is found to be remarkably enhanced. Third-order nonlinear optical susceptibility (χ3) of PRZTC was found to be 2 times higher than pure. All results suggest that the properties of ZTC crystals grown in presence of dye are enhanced and can be considered as better contender in various nonlinear devices.     

Characterization and Evaluation of Thermal Stability and Uniformity of a Liquid Temperature Bath Containing a Toluene Heat Pipe

The objective of this paper is to present a study carried out for the evaluation of the thermal stability and uniformity of a heat pipe modified water chamber. It can serve as a standard procedure that can be applicable to any other equilibrium thermal source used with water or any liquidus like medium for temperature distribution. These sources are utilized for comparison of high precision thermometers or sensor based temperature instruments having resolution of the order of 0.01 °C. In the present work a temperature water bath has been modified with a heat pipe cylindrical chamber provided with a forced circulation of fluid from the temperature controlled circulator. A standard platinum resistance thermometer with high precision resistance bridge was used for temperature measurement in the chamber at different locations horizontally and vertically as well. The thermal stability of this heat pipe modified chamber was evaluated to be ±0.006 to ±0.022 °C and uniformity to be ±0.015 to ±0.031 °C at different measured temperatures in the range from 5 to 90 °C. The uncertainty components due to these parameters have also been evaluated and reported in the paper.     

Radiation Thermometry Based on Photonic Crystal Fiber

Fiber-coupled radiometry allows for the radiometric measurement of high temperatures in environments where there is no line of sight to the target. However, transmission through conventional silica optical fibers degrades rapidly at elevated temperatures, and exotic fibers??such as sapphire fibers??typically cannot be bent. As part of a project to investigate the performance of solid oxide fuel cells, the feasibility of using an alternative fiber, solid-core silica photonic crystal fiber (PCF), was tested. The test system used an Inconel blackbody as a source, and a detection system based on an InGaAs array spectrometer with a wavelength range of 907 nm to 1681 nm. The temperature was determined from the spectrometer signal at particular wavelengths using the Planck relationship. Two tests were performed: (1) long-term high temperature soak tests to measure the drift and noise in thermal radiation levels, in which spectra are sequentially recorded over a long period of time with the blackbody cavity at a constant temperature and (2) temperature dependence tests, whereby thermal radiation spectra are recorded with the blackbody cavity at several temperatures. At 934 °C, the transmission of the PCF decreased at a rate of 0.078 % per hour corresponding to a temperature error of ?0.12 °C per hour. The transmission of conventional silica fiber decreased at a rate of 0.5 % per hour corresponding to a temperature error of ?0.8 °C per hour. While the PCF represents a significant improvement over conventional fiber, it is still not good enough for most practical purposes. At 600 °C there was no observable decline in transmission and there may be applications for PCF in that regime.     

Low-temperature sintered pollucite ceramic from geopolymer precursor using synthetic metakaolin

In this article, pollucite ceramic with high relative density and low coefficient of thermal expansion (CTE) was prepared from Cs-based geopolymer using synthetic metakaolin. Crystallization and sintering behavior of the Cs-based geopolymer together with thermal expansion behavior of the resulted pollucite ceramic were investigated. On heating at 1200 °C for 2 h, the amorphous Cs-based geopolymer completely crystallized into pollucite based on crystal nucleation and growth mechanism. Selected area diffraction analysis and XRD results confirmed the resulted pollucite ceramic at room temperature was pseudo-cubic phase with superlattice structure. Compared with Cs-based geopolymer using natural metakaolin, geopolymer using synthetic metakaolin in this article showed a much lower viscous sintering temperature range, which started at 800 °C, reached a maximum value of ?7.47 × 10^?4/°C at 1121.9 °C, and ended at 1200 °C. Cesium volatilization appeared only when temperature was above 1250 °C. Therefore, densified pollucite ceramic can be prepared from Cs-based geopolymer using synthetic metakaolin without cesium volatilization. Abnormal thermal shrinkage of pollucite ceramic was observed at temperature range from 25.3 to 54.6 °C because of pseudo-cubic to cubic phase transition, and its average CTE was 2.8 × 10^?6/°C from 25 to 1200 °C.     

Optical and structural investigations on iron-containing phosphate glasses

The article reports the preparation and complex characterization of iron-containing phosphate glasses considered to be ecological materials, as they contain non-toxic compounds related to environment. The oxide system Li₂O?CMgO?C(CaO)?CAl₂O₃?CP₂O₅?C(FeO/Fe₂O₃) was investigated in respect to its structural changes caused by MgO replacement with CaO and by the iron addition. UV?Cvis?CNIR (ultraviolet?Cvisible?Cnear infrared) spectroscopy as well as thermo-gravimetric (TG) measurements, differential thermo-analysis (DTA), X-ray diffraction (XRD) analysis, electronic paramagnetic resonance (EPR), and Mossbauer (nuclear gamma resonance) spectroscopy have been used to investigate redox states and coordination symmetry of iron, together with vitreous network changes during the heat treatment up to 1000 °C. UV?Cvis?CNIR transmission spectroscopy revealed no structural modifications when MgO was substituted by CaO, but noteworthy absorption bands attributed to Fe²⁺/Fe³⁺ species. TG analysis made in the 20?C1000 °C range shows low weight loss accompanied by several thermal effects, as evidenced by DTA. XRD patterns for the glass samples heat treated at about 700 °C revealed the presence of different phosphate crystalline phases containing Mg, Al, and Fe ions. EPR spectroscopy revealed the presence of paramagnetic Fe³⁺ ions and the change of the first coordination symmetry, when the samples are heated below the vitreous transition temperature. Mossbauer spectroscopy has evidenced two paramagnetic species, Fe²⁺ and Fe³⁺, both in octahedral coordination symmetry and a clustering process supported by only Fe³⁺ ions.     

Microstructural stability of Ag sinter joining in thermal cycling

As a heat-resistant die attach technology processed at low temperatures, three Ag filler-based sinter joining materials have been proposed. Among these, Ag flake pastes exhibited the greatest potential. Joining was carried out by sintering Ag nanoparticles/flakes in air at 200 °C for 60 min. All of the joined samples survived up to 1,000 thermal cycles in a temperature range from ?40 to 180/250 °C with a 30 min dwell time. In particular, the joining strengths with the Ag micron and, Ag nano-thick flake pastes maintained excellent strength. Neither thermal fatigue cracks nor large voids were observed in the Ag sintered layers. Thus, low-temperature and low-pressure sinter joining with Ag flakes is expected to have an application in high power semiconductor devices for ultra-high temperature operation.     

Effects of phosphorus content on generation and growth of cracks in nickel–phosphorus platings owing to thermal cycling

We observed crack generation and structural changes in electroless nickel–phosphorus (Ni–P) plating layers formed on copper-metalized silicon nitride substrates both during thermal cycling from ? 40 to 250 °C and during storage (not cycling) at 250 °C in order to investigate the effect of the phosphorus contents on crack generation and growth in the Ni–P platings. The used platings contained phosphorus at three different contents: 2.1 wt% [Ni–P(low)], 6.5 wt% [Ni–P(med)], and 10.9 wt% [Ni–P(high)]. The generation time and the amount of cracks were strongly dependent on their phosphorus contents. More cracks appeared after thermal cycling than after storage at 250 °C. In Ni–P(low), cracks were generated after 200 thermal cycles, whereas no cracks were observed even after 250 h of storage at 250 °C. In Ni–P(med) and Ni–P(high), both during thermal cycling and storage at 250 °C, cracks formed during or after crystallization of the amorphous layers. These results suggest that the primary factors affecting the generation of cracks in electroless Ni–P platings are crystallization of the Ni–P platings and repeated changes in thermal stress.     

Low-Temperature Blackbodies for Temperature Range from ?60?��C to 90?��C

Low-temperature cavity-type blackbodies (BB), VTBB and BB100K1, are developed at VNIIOFI for operation as IR radiation sources of the Middle Background Calibration Facility in the temperature range from ?60 °C to 90 °C, which is being constructed by KRISS for calibration of multi-spectral cameras for space applications. The VTBB model, featured by a 30 mm output aperture and hermetic housing and flange for mounting to a vacuum chamber, covers the complete temperature range under a vacuum environment (up to 10^?2 Pa), and the temperature range from 20 °C to 90 °C under open air conditions. BB100K1 has a wide aperture of 100 mm diameter, which shows stable operation in the temperature range from ?60 °C to 90 °C inside a vacuum chamber, and in the temperature range from ?40 °C to 90 °C in a dry-air or inert-gas environment with the usage of an extra hood with an aperture. The effective emissivity of the radiating cavities of both BB, covered with Lord Aeroglaze Z306 black paint, was calculated with the usage of STEEP3 Monte-Carlo simulation software, taking the measured temperature gradients into account. The numerical calculations yield an emissivity of at least 0.9997 for the VTBB cavity, and 0.997 for the BB100K1 cavity. The radiating cavity temperature of VTBB and BB100K1 is stabilized at the level of ±0.01 °C by means of an external precise closed-loop liquid thermostat (Huber Unistat 705 model). The temperature distribution along the radiating cavities and across the BB bottoms is monitored by five precision PRT thermometers and a digital multimeter equipped with a scanner card. Experimental tests using a thermal camera at KRISS demonstrated high-temperature uniformity of both radiation sources not exceeding ±50 mK over the entire temperature range, in vacuum as in a dry-air environment. The combined standard uncertainty of VTBB and BB100K1 temperature measurements accounts for about 40 mK within the range of their working temperatures.     

Capturing mixed-mode cracking of asphalt concrete using the Arcan test

Reflective cracking of asphalt concrete has been shown to be a combination of both opening (Mode I) and sliding (Mode II) cracking. The Arcan test configuration was developed at Southeast University to test Mode I, Mode II and three levels of mixed mode. This research used two asphalt concrete mixtures with the same asphalt cement but with two gradations: AC-20 and AC-10; four loading rates: 0.1, 0.5, 1.0 and 10 mm/min; and three testing temperatures: ? 10, 0, +10°C, to explore the use of the Arcan test. Overall, it was found that the Arcan test is able to capture mixed-mode characteristics of asphalt concrete, but these characteristics can change significantly over a relatively small range of temperatures. Although Mode II fracture energy was highest at ? 10°C, with a steadily declining fracture energy as the level of Mode I increased, there were no clear trends at 0 or +10°C.     

Disseminating the ITS-90 Traceability in Industry��An Intercomparison of Temperature Block Calibrators

An international intercomparison has been carried out with a commercial dry block calibrator as a transfer standard by the Danish Technological Institute (DTI). The intercomparison involved 16 participating laboratories from five European countries. The intercomparison comprised five measurement points in the range from ?20 °C to +150 °C. The purposes of the intercomparison were twofold: to compare the results of the participating laboratories during calibration of a dry block calibrator and to establish the dry block calibrators?? reproducibility and suitability both as a transfer standard and as a working measurement standard for disseminating the ITS-90 traceability in industry. The characterization and performance of state- of-the-art multi-zone dry block calibrators and the results of the intercomparison are presented.     

Preparation of CuInSe2 thin films by selenization of co-sputtered Cu-In precursors using rapid thermal processing

CuInSe₂ thin films have been synthesized by selenization of co-sputtered Cu-In precursors using rapid thermal processing (RTP). Heat treatments from 400 to 450 °C for periods between 1 min and 10 min were carried out on (Cu-In)/Se precursors. Phase evolution as function of reaction temperature and holding time was analyzed according to XRD and SEM results. Severe Se loss during RTP was proved in our experiments and has been reported by many other researchers. To solve the problem, a new effective way of reducing Se loss was presented, which is based on low temperature heat treatment at 250 °C before high temperature annealing. Nearly single-phase CuInSe₂ thin films have been achieved by annealing precursors at 250 °C for 5 min then 450 °C for 1 min. Se loss can be significantly reduced via low temperature heat treatment by the fact that under 250 °C, Se is evaporated mildly and largely consumed as Cu-Se and In-Se binary selenides.     

Study on Mechanical Behavior of CVD-SiC Coated C/SiC Composites under Simulated Space Environments

SiC coating was prepared on the surface of C/SiC composites by chemical vapor deposition (CVD) method, and then mechanical behavior of CVD-SiC coated C/SiC composites under cold and thermal cycling had been investigated. Specimens were thermally cycled between the temperatures of ?100 °C and 100 °C for up to 200 cycles, respectively. The coating was characterized by XRD, SEM and EDS. The results showed that there were no significant changes in the flexural property. CVD-SiC coated C/SiC composites had good mechanical stability in above simulated space environments. While great changes occurred on both elements and structure of the coating, from homogeneous single-phase of SiC into the inner layer of SiC and the outer of C, which caused the change of the bending strength.