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A square spiral incision was introduced into a 15 × 15 cm regular quadrilateral conductive film to study the modulation of electrothermal distribution by kirigami structure. Based on the simulation of finite element method, the transition from thermal focusing to thermal defocusing could be achieved by increasing the length of connection between adjacent modules. The effective electrothermal area can be increased by nearly two times through increasing the length increment of the notch length between adjacent modules. The maximum temperature was decreased from 254 °C to 44 °C, and the temperature difference was adjusted from 76 °C to 4 °C by increasing the number of kirigami module. Through the contact temperature measurement experiment on graphite paper kirigami structure, the trends could be verified. By creating an equivalent circuit model and considering the influence of heat conduction, the peak temperature at the center of the structure and the decrease of the overall temperature could be explained. By deriving the relationship between the temperature of conductive film of kirigami structure with time and position, the electrothermal characteristics of previously reported graphene kirigami structure could be predicted. [ABSTRACT FROM AUTHOR]

Utilities need to understand the aging of paper insulation in order to prolong the life of transformers. If the paper becomes severely degraded, it loses its mechanical strength and thus its ability to insulate the windings. [ABSTRACT FROM PUBLISHER]

Utility asset managers and engineers are concerned about the life and reliability of their power transformers which depends on the continued life of the paper insulation. The ageing rate of the paper is affected by water, oxygen and acids. Traditionally, the ageing rate of paper has been studied in sealed vessels however this approach does not allow the possibility to assess the affect of oxygen on paper with different water content. The ageing rate of paper has been studied for dry paper in air (excess oxygen). In these experiments we studied the ageing rate of Kraft and thermally upgraded Kraft paper in medium and high oxygen with varying water content. Furthermore, the oxygen content of the oil in sealed vessels is low which represents only sealed transformers. The ageing rate of the paper has not been determined for free breathing transformers with medium or high oxygen content and for different wetness of paper. In these ageing experiments the water and oxygen content was controlled using a special test rig to compare the ageing rate to previous work and to determine the ageing effect of paper by combining temperature, water content of paper and oxygen content of the oil. We found that the ageing rate of paper with the same water content increased with oxygen content in the oil. Hence, new life curves were developed based on the water content of the paper and the oxygen content of the oil. [ABSTRACT FROM PUBLISHER]

The paper analyses the effect of waste sludge from paper industry (paper sludge) on physical and mechanical properties of clay bricks, their microstructure and resistance to freezing and thawing. Paper sludge is not hazardous industrial waste mainly consisting of cellulose and calcite. Clay bodies were made from the mix containing from 5% to 20% of paper sludge and fired at 900 °C and 1000 °C temperatures. Open pore structure in the clay body is developed as a result of burnt cellulose fibres and calcite decarbonization. Physical and mechanical properties of clay bodies change depending on the content of added PS: shrinkage, density and compressive strength reduce, water absorption and effective porosity increase. It is recommended to add 5% of paper sludge to the clay body and fire it at 900 °C temperature, or alternatively add 5–15% of paper sludge and fire the clay body at 1000 °C temperature. In terms of resistance to freezing and thawing, such products are regarded as frost resistant in moderately aggressive environment, i.e. in structures protected from direct environmental effects. [ABSTRACT FROM AUTHOR]

We describe a low cost optical temperature sensor that is simple to manufacture. The sensor is constructed by simple soaking of paper in a solution of the temperature sensitive luminescent indicator Ru(phen) 3 and subsequent lamination of the dried paper. Lamination prevents O 2 diffusion to the indicator and thus eliminates O 2 cross-sensitivity. The temperature sensitivity was up to −2% change in luminescence lifetime per K, a t 90 response time of 10 s. Besides luminescence lifetime based measurements, the sensor is well suited for ratiometric imaging with simple RGB cameras, where the temperature dependent red luminescence can be referenced by the blue luminescence of the optical brightener in the paper. [ABSTRACT FROM AUTHOR]

Activation energy is popularly used for the estimation of remaining life of transformer insulation. It is defined as the average rate of all reactions that happen with cellulose. Existing literature shows that the activation energy of oil–paper insulation can be obtained from polarization depolarization current (PDC) and return voltage measurement (RVM) data that are measured at a specific temperature. It is practically difficult to ensure the same measurement temperature for both PDC and RVM data. On the other hand, PDC data and its analysis get influenced by de-trapping current. This de-trapping current is generated by ionic charge carriers that get freed from trap sites during PDC measurement process. Formation of these trap sites is related to physical, chemical reactions that happen at oil–paper interface. This paper proposes a methodology which uses de-trapped charge, dislodged from deep and shallow traps, to assess insulation condition and for the prediction of activation energy. Thus, eliminating the need of RVM data. The proposed method is tested using data collected from various real-life in-service transformers. [ABSTRACT FROM AUTHOR]

Ambient temperature geopolymerization of paper sludge ashes (PS-ashes) discharged from paper mills was studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), induction coupled plasma atomic emission spectrometry (ICP-AES), and X-ray absorption near edge structure (XANES). Two varieties of alkaline liquors were used in the PS-ash based geopolymers, corresponding to aqueous Na-metasilicate and Na-disilicate compositions. PS-ashes were found to be semi-crystalline and to have porous structures that make it possible to absorb much liquor. Flexural strengths of PS-ash-based geopolymers with liquor/filler ratios (L/F) of 1.0-1.5 ranged from 0.82 to 1.51 MPa at 4 weeks age, depending on PS-ashes and liquors used. The reaction process of the constituent minerals of the PS-ash is discussed. Furthermore, we attempted to solidify hazardous water contaminated with radioisotopes. Non-radioactive strontium and cesium nitrates were added as surrogates at a dosage of 1% into the PS-ash-based geopolymers. Generally, high immobilization ratios up to 99.89% and 98.77% were achieved for Sr2+ and Cs+, respectively, depending on the source of PS-ashes, alkaline liquors, and material ages. However, in some cases, poor immobilization ratios were encountered, and we further discussed the causes of the instability of derived geopolymer gels on the basis of XANES spectra. [ABSTRACT FROM AUTHOR]

The relation between ageing and space charge is a hot area, but there is little direct evidence. In this paper, oil-paper samples were exposed to 20-kV/mm DC electrical field, 130°C temperature or both 20-kV/mm DC electrical field and 130°C temperature separately. Charge transport through them was analyzed at intervals by the pulsed electroacoustic (PEA) method. We find that the quantity of trapped charge increases with stressing durations, no matter what kind of stress oil-paper is exposed to. That indicates that energy release through space charge movement, such as charge trapping/detrapping and recombination, is another reason for traps generation besides deterioration caused by thermal ageing. However, because the difference in cellulose degradation mechanism among them, charge transport dynamics are thereby different under different stressing conditions. Space charge accumulates faster inner electrothermally stressed oil-paper than that inner another two kinds of oil-paper, and the sign of trapped charge is positive if oil-paper is electrically or electro-thermally stressed. The latter behavior is discussed in terms of electromagnetic dynamics due to cavity within oil-paper once there is external electric field. [ABSTRACT FROM PUBLISHER]

Paper materials are used as the insulation of power transformers. Over time these materials slowly degrade, until they reach a point when they no longer function effectively as transformer insulation, and the transformer has then reached its end of life. The aging rate of paper is affected by temperature, water, oxygen and acids. Investigations have been performed previously on Kraft and Kraft thermally upgraded types of paper. However, a different type of paper used in transformer insulation, Grade 3 presspaper (which contains cotton), has not been extensively tested and compared to Kraft paper. In these experiments we studied the aging rate of Grade 3 presspaper and compared it to our previous studies of Kraft paper. Traditionally, the aging rate of paper has been studied in sealed vessels. The problem with this approach is that the chemical environment within the vessel will change during aging, and so the aging rate will be affected. In our experiment setup we controlled the water and oxygen content to more accurately determine the aging rate. Similarly to Kraft paper, the aging rate of Grade 3 presspaper with the same water content increased with oxygen content in the oil. Life curves were developed based on the water content of the paper and the oxygen content of the oil. [ABSTRACT FROM AUTHOR]

Handmade paper utilizes direct dyes for imparting it bright colors to be used in wedding cards, fancy, decorative arts, etc. The effluent of handmade paper industry faces problem of highly colored effluent. The present study aims at decolorization of direct red and direct blue dyes, used abundantly in the industry, with the help of ozonation treatment. The batch studies have been conducted on decolourization of synthetic samples of these dyes at various initial concentrations, temperature, and pH. The effect of these parameters has been studied on decolorization efficiency. The maximum decolorization is achieved at pH of 10 and temperature of 313 K. The equilibrium time of decolorization with ozonation treatment for direct red and direct blue dye for 50 ppm initial concentration was 6 and 4 min, respectively. The kinetics of decolorization was found to be pseudo-first-order type. [ABSTRACT FROM PUBLISHER]

This paper elucidates the question whether bubble effect can possibly take place in the insulation of OIP (Oil Impregnated Paper) type of bushings. The investigations were performed on a bushing insulation model and indicated to a possibility that the effect may occur. Presence of metallic screens in the insulation does not limit the development of gas bubbling; they only force the motion of water vapor bubbles along the model axis. The temperature dependence of bubble initiation on the water content in paper part of the bushing insulation is similar to the presented earlier in literature characteristics for bubbling in main insulation of power transformers. The possibility of bubble effect occurrence may explain the relatively frequent cases of transformer bushing failures. [ABSTRACT FROM PUBLISHER]

Abstract: This study explores the possibility of converting a self-supporting, randomly aligned, low impedance multi-wall carbon nanotube (MWCNT) paper into a resistive temperature measurement unit working at ambient pressure in air in the 25–70°C range. Thermosensitization was achieved by decorating the surface of the films with pyroelectric CsNO3 or LiNbO3 crystals. Assuming a linear temperature response, temperature coefficient of resistance values of −0.158%°C−1 and −0.246%°C−1 were calculated for CsNO3 and LiNbO3 doped films, respectively. The corresponding temperature measurement accuracies (2.2°C and 3.0°C) are acceptable for some applications but the precision of the temperature measurement needs to be improved. [Copyright &y& Elsevier]

This comment deals with the proposed accuracy and the interpretation of results of experimental measurements of the temperature dependent thermal conductivity of porous heat storage media carried out by the authors of the original paper. We argue that the described reduction of the thermal conductivity of the specimens is probably mainly an artefact because boundary conditions of the used measurement device have been disregarded. Furthermore, we make some suggestions how to repeat the measurements to gain more proper results. [ABSTRACT FROM AUTHOR]

In order to distinguish the influences of moisture and aging on the frequency domain dielectric response of oil-paper insulation and better apply frequency domain spectroscopy (FDS) to assess the insulation condition of power transformers, the oil-paper insulation samples with different moisture contents and different aging states were prepared in the laboratory. The FDS of the samples were tested and a group of characteristic parameters were extracted from dissipation factor (tan?) curves which could be used to assess the moisture content and aging states of oil-paper insulation respectively. The quantitative relationship among characteristic parameters, degree of polymerization (DP) and moisture contents (Km.c) was accurately established. The observations show that the proposed characteristic parameters are sensitive to the moisture in 10-3-102Hz, while the aging states influence the characteristic parameters in 10-3-10-1Hz. Meanwhile, an exponential relationship equation which could be used to assess the oil-paper insulation condition was established among the characteristic parameters, DP and the moisture content. Finally, the evaluation technique proposed in this paper was used to diagnose the insulation condition of several field transformers in this way, and its validity was preliminary and reasonably verified. [ABSTRACT FROM AUTHOR]

Abstract: The thermal behavior of semi-anthracite coal, paper sludge and their blends during pyrolysis and combustion processes was investigated in this study. The experiments were conducted in a differential thermogravimetric analyzer at different heating rates (10K/min, 20K/min and 30K/min) and at temperatures ranging from 310K to 1300K. The results revealed that de-volatilization of paper sludge occurred earlier with a higher rate, and that the process was further accelerated under oxygen-enriched conditions. The blends had integrative thermal profiles that reflected both paper sludge and coal. In addition, the blends showed different ignition and combustion behavior depending on the percentage of sludge. Two types of non-isothermal kinetic analysis methods were applied to evaluate the combustion processes. The kinetic parameters of the blends confirmed the improved ignition characteristics. In addition, both the TG profiles and activation energy indicated that the combustion of their blends with low percentages of sludge, such as 10 wt.%, were similar to that of coal. These experimental results help explain and predict the behavior of coal and paper sludge blends in practical applications. [ABSTRACT FROM AUTHOR]

The hot spot temperature inside the windings of the oil-immersed power transformers may exceed 200 °C due to some winding deficiencies, posing negative impact on the paper insulation. A series of heating experiments are deliberately conducted with oil-paper insulation samples to study the influence of the hot spot temperature ranging from 120 to 280 °C, and the insulation degradation is characterized by the breakdown voltage (BDV) and the degree of polymerization (DP). Furthermore, surface morphology, water content and cellulose degradation mechanism are analyzed so as to reveal the causes of the above phenomena. The experimental results indicate that with increase of the hot spot temperature, the breakdown voltage increases after the first drop, while the DP continues to decline in the tested temperature range. No obvious linear relationship is observed between the hot spot temperature and the DP or the BDV. Regarding the test samples the authors have studied, the inflection point of the hot spot temperature for the insulation deterioration is found to be between 240 and 260 °C. The proposed research presents a fundamental reference for assessment of the winding insulation degradation from the viewpoint of hot spot temperature. [ABSTRACT FROM AUTHOR]

As the temperature gradient always exists in the insulation of power equipment, the influence of temperature gradient on oil-impregnated paper insulation is studied by experiments and simulation. It's found that in the both single-layer and double-layer structures, the heterocharges always appear near the lower temperature electrode, and increase with the enhancement of temperature gradient and field stress, resulting in more considerable field distortion. However, there are more heterocharges in the single-layer samples while the field distortion is more severe in double-layer samples. Numerical simulations were carried out to investigate the mechanism of temperature gradient effect. It is indicated that the space charge accumulation is mainly due to the temperature dependence of the charge injection and conduction. The behavior of interface charges can be well described by assuming an energy barrier for charge transportation at the interface. [ABSTRACT FROM AUTHOR]

Worldwide, there is a growing need for use of recyclable and biodegradable materials, made from natural resources, for a variety of applications. This trend is followed by the printing industry as well, which is trying to use environmentally friendly materials and reduce the consumption of environmentally unfriendly materials. In addition, the used materials should give the satisfying quality of the end-product. Thermochromic inks can be reversible (color change is multiple) or irreversible (color change is one-time and permanent). Irreversible printing inks are initially either colorless or colored and when exposed to high temperatures they get colored or change to another color. Therefore, the aim of this paper is to examine the possibilities of two printing substrates (uncoated and coated) for the application of irreversible thermochromic inks in order to find a more environmentally friendly option that gives a satisfactory print quality. The dynamics of color change was monitored through one heating cycle every few degrees. Their colorimetric characteristics were described using spectral reflection curves and the CIELAB color system. Based on the obtained results, it can be concluded that with the change of temperature, the color tone changes slowly and continuously. The differences are evident for the selected printing substrates due to their different properties. However, these variations are imperceptible to the eye of the observer and according to the obtained results, it can be concluded that the tested inks behave similarly on the used substrates. In addition, more environmentally sustainable materials can be a good option in the use of printing with irreversible water-based thermochromic inks. [ABSTRACT FROM AUTHOR]

Abstract: The present work introduces mild – room temperature – potassium permanganate treatment of cellulosic materials, namely already bleached pulps. Such treatment represents a new approach for upgrading pulp and paper quality, which is lacking in the literature. Potassium permanganate was investigated as a purifying and mild oxidizing agent for commercial already bleached softwood and bagasse pulps. It was found that treatment of the bleached beaten pulps, with 0.25–2% KMnO4 (based on pulp weight), led to significant improvement in paper properties. The strength (breaking length) increased greatly and the brightness increased significantly due to treatment. The improvements were related to the degree of polymerization, and to the alphacellulose content of pulps. Moreover, potassium permanganate serves as a disinfectant and deodorizer. Thus treatment of bleached pulps with KMnO4 is a promising remedy for the side effects which pulps suffer, during transportation and storage, before papermaking. [Copyright &y& Elsevier]

In this article, the author presents comments on the paper by P. A. Enright and C. M Fleischmann about the associated uncertainty in the measurement of heat release rate (HRR) for Cone Calorimeter. The author argues that the contribution of the stoichiometric expansion factor ß on the uncertainty of HRR is not significant, but rather negligible. The author remarks on the impossibility of the parameters demonstrated by the authors of the paper in the HRR uncertainty analysis.

Abstract: Dr. E. Storms has published a Letter [E. Storms, Comment on papers by K. Shanahan that propose to explain anomalous heat generated by cold fusion, Thermochim. Acta, 2006] in which he argues that in a sequence of recent papers, the apparent excess heat signal claimed by Dr. Shanahan to arise from a calibration constant shift is actually true excess heat. In particular he proposes that the mechanisms proposed that foster the proposed calibration constant shifts cannot occur as postulated for several reasons. As well, he proposes Shanahan has ignored the extant data proving this. Because this Letter may lend unwarranted support to acceptance of cold fusion claims, these erroneous arguments used by Storms need to be answered. [Copyright &y& Elsevier]

Moisture dynamics in cellulosic insulation can be estimated using a mathematical model of diffusion based on Fick's second law [1], [2]. The main parameter of this mathematical model is the moisture diffusion coefficient, and the precision of the model is dependent on using an accurate value of this coefficient. Various researchers have obtained expressions for the moisture diffusion coefficient for cellulosic insulation, such as Kraft paper or pressboard, applying different methodologies [3]–[10]. Several values of the diffusion coefficient can be found in the literature represented by mathematical expressions, tables, or experimental curves, relating the dependence of the coefficient with the local moisture concentration and temperature. Some of these coefficients have been determined for nonimpregnated insulation (mainly Kraft paper and pressboard) and others for oilimpregnated paper. Most of these coefficients were determined more than 25 years ago [11], and until now, no coefficients have been proposed for oil-impregnated pressboard. [ABSTRACT FROM AUTHOR]

Low resistance Ohmic contacts using Ti/Au metallization on n-type amorphous indium zinc oxide (IZO) (n∼5×1020 cm-3) deposited on paper substrates are reported. The minimum specific contact resistivity of 8×10-7 Ω cm2 was achieved on IZO films both as-deposited and for annealing temperatures of up to 125 °C. The contact resistance increased to 4×10-6 Ω cm2 at 175 °C. The sheet resistance was found to vary from 24 to 17 Ω/sq, and the transfer resistance was ∼0.045 Ω mm for the as-deposited and low temperature annealed samples. The contact resistance was independent of measurement temperature, indicating that field emission plays a dominant role in the current transport. Such Ohmic contacts achieved with little or no annealing are important for paper based electronics requiring low temperature processing (<200 °C). [ABSTRACT FROM AUTHOR]

This article presents a review of work by William J. Parker on heat release rate measurements by oxygen consumption. It recounts incidents that provided motivation for Parker to begin investigating new methods for measuring heat release rate. It also discusses the history and evolution of oxygen consumption calorimetry.

The technique of qualitative thermal analysis is described by the example of the study of a Cu-Ni binary system. The main parameters affecting the results of determination of phase transformation temperatures are listed. Recommendations are given for choosing experimental conditions for determining the liquidus and solidus temperatures of multicomponent systems. Techniques for processing the results of differential thermal analysis are presented. [ABSTRACT FROM AUTHOR]

An isothermal microcalorimeter has been used to study ageing of oil impregnated kraft paper. Under the assumption that the heat flow is proportional to the ageing rate of paper it is found that activation energy seems to be lower for oxidation than for hydrolysis. This observation corresponds well with results obtained by traditional ageing methods. The results have also been confirmed by measuring the changes in DP of the samples used in the calorimetric measurements. Comparing degradation of aged and unaged oil impregnated paper in air gave a higher heat flow for the unaged paper, but the activation energy for the processes remained the same. The process was also studied with another cellulosic material and in addition varying size of the sample holder of the calorimeter, giving similar results. Hence, since the microcalorimeter appears to give the same qualitative ageing characteristics for oxidation and hydrolysis as more time consuming methods, calorimeter could be a useful tool for quick ageing investigations. [ABSTRACT FROM PUBLISHER]

Purpose: The purpose of this paper is to analyse the obtained experimental data, which is advisable to use to verify the thermophysical model of the thermal regime of a separate premise while using ceramic electric heating panels for heating purposes. Design/methodology/approach: The experimental studies were carried out at the scientific thermophysics laboratory with the help of up-to-date equipment (including the design for these studies). After gathering experimental data, it was analysed, and with its help, a CFD model of the thermal regime of the laboratory premise would be verified. Findings: The conducted experimental studies showed that in the artificially created quasistationary thermal regime of the laboratory premise, the air temperature varied with height in a small interval. This makes it possible to state that when using ceramic electric heaters as heating devices, the air temperature is relatively evenly distributed over the height of the premise. Research limitations/implications: The research provides original experimental data and findings for further CFD modelling of the thermal regime of the premise while using heating ceramic panels. Practical implications: The mentioned in the paper research methods as well as obtained experimental data, could be used in further studies of modern heating systems. Another use of the results - during the validation of CFD models. Originality/value: The paper includes the design and methodology of creating the original experimental stand for research of the different heating systems types. [ABSTRACT FROM AUTHOR]

Abstract: Dr. Shanahan has published two papers (Thermochim. Acta 428 (2005) 207, Thermochim. Acta 382 (2002) 95) in which he argues that excess heat claimed to be produced by cold fusion is actually caused by errors in heat measurement. In particular, he proposes that unrecognized changes in the calibration constant are produced by changes in the locations where heat is being generated within the electrolytic cell over the duration of the measurement. Because these papers may lend unwarranted support to rejection of cold fusion claims, these erroneous arguments used by Shanahan need to be answered. [Copyright &y& Elsevier]

The reference characteristics of complex permittivity of the transformers insulation solid component were determined for use in the precise diagnostics of the power transformers insulation state. The solid component is a composite of cellulose, insulating oil and water nanoparticles. Measurements were made in the frequency range from 10−4 Hz to 5000 Hz at temperatures from 293.15 to 333.15 K. Uncertainty of temperature measurements was less than ±0.01 K. Pressboard impregnated with insulating oil with a water content of (5.0 ± 0.2) by weight moistened in a manner maximally similar to the moistening process in power transformers was investigated. It was found that there are two stages of changes in permittivity and imaginary permittivity components, occurring for low and high frequency. As the temperature increases, the frequency dependencies of the permittivity and imaginary permittivity component shifts to the higher frequency region. This phenomenon is related to the change of relaxation time with the increase in temperature. The values of relaxation time activation energies of the permittivity ΔWτε′ ≈ (0.827 ± 0.0094) eV and the imaginary permittivity component ΔWτε″ = 0.883 eV were determined. It was found that Cole-Cole charts for the first stage are asymmetric and similar to those described by the Dawidson–Cole relaxation. For stage two, the charts are arc-shaped, corresponding to the Cole-Cole relaxation. It has been established that in the moistened pressboard impregnated with insulating oil, there is an additional polarization mechanism associated with the occurrence of water in the form of nanodrops and the tunneling of electrons between them. [ABSTRACT FROM AUTHOR]

To solve the temperature/strain cross-sensitivity problem, simultaneous measurement of temperature and strain can be achieved by using the two spectra of LP01 mode and LP11 mode in few-mode fiber Bragg grating (FM-FBG). However, in the same fiber the temperature/strain sensitivity difference is small, so the sensing accuracy is limited greatly. In this paper, we calculate the relation between sensing accuracy and sensitivity-difference and obtain that the enlarged sensitivity difference could improve the sensing accuracy. FBGs are engraved on two kinds fibers single-mode (SM) and few-mode (FM) with different geometrical dimensions; the sensing coefficients of LP01 mode in SM-FBG and LP11 mode/LP01 mode in FM-FBG are calibrated firstly and then are used to sense the temperature/strain. The experimental results show that parallelly using LP01 mode in SM-FBG and LP11 mode in FM-FBG achieves simultaneous measurement of temperature and strain, and error is reduced greatly compared with the sensing results using LP11 mode and LP01 mode in FM-FBG or using LP01 mode in SM-FBG and LP01 mode in FM-FBG, where the wavelength-temperature/strain coefficient difference is maximum. The temperature measurement error is 1.64°C, and the strain measurement error is 20.04 με, which is consistent with the theoretical analysis. The sensing results provide technical reference for FBG multi-parameter sensing measurement and the practical engineering application. [ABSTRACT FROM AUTHOR]

Purpose: In order to include the non-negligible lag relaxation time feature that is characteristic of heat transfer in biological bodies, the classical Fourier's law of heat conduction has to be generalized as the Maxwell–Cattaneo law resulting in the thermal-wave model of bio-heat transfer. The purpose of the paper is to retrieve the unknown time-dependent blood perfusion coefficient in such a thermal-wave model of bio-heat transfer from (non-intrusive) measurements of the temperature on an accessible sub-portion of the boundary that may be taken with an infrared scanner. Design/methodology/approach: The nonlinear and ill-posed problem is reformulated as a nonlinear minimization problem of a Tikhonov regularization functional subject to lower and upper simple bounds on the unknown coefficient. For the numerical discretization, an unconditionally stable direct solver based on the Crank–Nicolson finite-difference scheme is developed. The Tikhonov regularization functional is minimized iteratively by the built-in routine lsqnonlin from the MATLAB optimization toolbox. Numerical results for a benchmark test example are presented and thoroughly discussed, shedding light on the performance and effectiveness of the proposed methodology. Findings: The inverse problem of obtaining the time-dependent blood perfusion coefficient and the temperature in the thermal-wave model of bio-heat transfer from extra boundary temperature measurement has been solved. In particular, the uniqueness of the solution to this inverse problem has been established. Furthermore, our proposed computational method demonstrated successful attainment of the perfusion coefficient and temperature, even when dealing with noisy data. Originality/value: The originalities of the present paper are to account for such a more representative thermal-wave model of heat transfer in biological bodies and to investigate the possibility of determining its time-dependent blood perfusion coefficient from non-intrusive boundary temperature measurements. [ABSTRACT FROM AUTHOR]

A high-sensitivity plasmonic photonic crystal fiber (PCF) sensor is designed and a metal thin film is embedded for achieving surface plasmon resonance (SPR), which can detect the magnetic field and temperature simultaneously. Within the plasmonic PCF sensor, the SPR sensing is accomplished by coating both the upper sensing channel (Ch1) and the lower sensing channel (Ch2) with gold film. In addition, the temperature-sensitive medium polydimethylsiloxane (PDMS) is chosen to fill in Ch1, allowing the sensor to respond to the temperature. The magnetic field-sensitive medium magnetic fluid (MF) is chosen to fill in Ch2, allowing this sensor to respond to the magnetic field. During these processes, this proposed SPR-PCF sensor can achieve dual-parameter sensing. The paper also investigates the electrical field characteristics, structural parameters and sensing performance using COMSOL. Finally, under the magnetic field range of 50–130 Oe, this sensor has magnetic field sensing sensitivities of 0 pm/Oe (Ch1) and 235 pm/Oe (Ch2). In addition, this paper also investigates the response of temperature. Under the temperature range of 20–40 °C, Ch1 and Ch2 have temperature sensitivities of −2000 pm/°C and 0 pm/°C, respectively. It is noteworthy that the two sensing channels respond to only a single physical parameter; this sensing performance is not common in dual-parameter sensing. Due to this sensing performance, it can be found that the magnetic field and temperature can be detected by this designed SPR-PCF sensor simultaneously without founding and calculating a sensing matrix. This sensing performance can solve the cross-sensitivity problem of magnetic field and temperature, thus reducing the measurement error. Since it can sense without a matrix, it further can solve the ill-conditioned matrix and nonlinear change in sensitivity problems in dual-parameter sensing. These excellent sensing capabilities are very important for carrying out multiparameter sensing in complicated environments. [ABSTRACT FROM AUTHOR]

The article offers the author's insights on the study by O. A. Anisimov and colleague on the estimates of climate change in the regions in Russia in the 20th and 21st century based on observation. The authors state that the objectives of the study was to improve the spatial averaging technique of meteorological variables. They mention that it centers on the comparison of estimates of regional changes in precipitation and temperature without clear formulated conclusions.

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A highly sensitivity balloon-like fiber interferometer based on ethanol coating is presented in this paper. The Mach–Zehnder interferometer is formed by bending a single-mode fiber to a balloon-like structure and nested in the Teflon tube. Then, an ethanol solution was filled into the tube of the balloon-like fiber interferometer by the capillary effect. Due to the high sensitivity of the refractive index (RI) of ethanol solutions to temperature, when the external temperature varies, the optical path difference changes. The change in temperature can be detected by the shift in the interference spectrum. Limited by the size of the balloon-like structure, three kinds of these structures with different sensitive lengths were prepared to select the best parameters. The sensitive lengths were 10, 15 and 20 mm, respectively, and the RI detection performance of each structure in 10~26% NaCl solutions was investigated experimentally. The results show that when the sensitive length is 20 mm, the RI sensitivity of the sensor is the highest, which is 212.88 nm/RIU. Ultimately, the sensitive length filled with ethanol is 20 mm. The experimental results show that the temperature sensitivity of the structure is 1.145 nm/°C in the range of 28.1 °C~35 °C, which is 10.3 times higher than that of an unfilled balloon-like structure (0.111 nm/°C). The system has the advantages of low cost and easy fabrication, which can potentially be used in high-precision temperature monitoring processes. [ABSTRACT FROM AUTHOR]

The accurate calculation of the hotspot temperature of the cable intermediate joint can effectively guarantee the safe operation of the transmission and distribution network. This paper addresses the limitations of the current method of estimating hotspot temperature solely from surface temperature measurements. Specifically, we focus on a 110 kV single-core cable as our subject of study. We started by establishing a simulation model for the temperature field at the intermediate joint to generate data samples. Subsequently, the NCA (neighborhood component analysis) algorithm was employed to select the optimal measurement points on the cable's surface. This allowed determination of the quantity and location of characteristic points. Finally, we developed a cascading inversion model, which consists of a radial inversion model and an axial inversion model, based on the extreme learning machine algorithm. The example results show that the mean squared error of hotspot temperature obtained by cascade inversion and direct inversion is 6.95 and 24.71, respectively, indicating that cascade inversion can effectively improve the inversion accuracy. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the homogenization of long-term temperature data series in Porto, Lisbon, and Coimbra, Portugal. The study used metadata, a visual analysis, and homogeneity tests. Results show that all the data series have both internal climatic and non-climatic origins.

Purpose: The purpose of the investigations was to characterise and describe the modern creep-resistant Thor 115 steel for supercritical power units. Design/methodology/approach: The investigations were performed based on the knowledge and experience of the author, the preliminary results of his own research and the available literature on the subject-matter of the considerations presented in the paper. Findings: Modern steel Thor 115 was subjected to overall analysis in terms of its use as a potential heat-resistant structural material for power plant components. Based on the preliminary results of own research and the available literature data, it has been shown that the analysed steel may be a structural material of full value if the assumed creep resistance in the service temperature range of 600-650°C is confirmed. Research limitations/implications: The comprehensive analysis of degradation of microstructure of the steel after ageing (and/or creep) requires TEM examinations. Finding the correlation between the creep and ageing conditions and changes in the microstructure of the steel. Practical implications: The investigations carried out as part of the paper and the considerations on the subject-matter of the analysed steel may be the basis for the development of a database of material characteristics for steels, alloys and welded joints. Originality/value: The analysis of chemical composition, heat treatment and mechanical properties and the investigations of microstructure of Thor 115 steel are presented. [ABSTRACT FROM AUTHOR]

A homogeneous set of temperature measurements obtained from the DOI/GTN-P Deep Borehole Array between 1973 and 2013 is presented. The 23-element array is located on the Arctic Slope of Alaska, a region of cold continuous permafrost. Most of the monitoring wells are situated on the arctic coastal plain between the Brooks Range and the Arctic Ocean, while others are in the foothills to the south. The data represent the true temperatures in the wellbores and surrounding rocks at the time of the measurements; they have not been corrected to remove the thermal disturbance caused by drilling the wells. With a few exceptions, the drilling disturbance is estimated to have been of order 0.1 K or less by 1989. Thus, most of the temperature measurements acquired during the last 25 yr are little affected by the drilling disturbance. The data contribute to ongoing efforts to monitor changes in the thermal state of permafrost in both hemispheres by the Global Terrestrial Network for Permafrost (GTN-P), one of the primary subnetworks of the Global Terrestrial Observing System (GTOS). The data will also be useful for refining our basic understanding of the physical conditions in permafrost in arctic Alaska, as well as provide important information for validating predictive models used for climate impact assessments. The processed data are available from the ACADIS repository at doi:10.5065/D6N014HK. [ABSTRACT FROM AUTHOR]

In the design of rear-axle locking differentials, the desired high locking effect is often achieved using wet multi-plate clutches. This study conducts an in-depth investigation into the spontaneous damage behavior of these clutches through a series of methodical experimental tests. It focuses on three different clutch variants, each equipped with organic friction linings—namely, paper-based, carbon composite, and woven carbon—and undertakes a comparative analysis of their respective damage typologies. The experimental analysis identifies and characterizes patterns of damage, notably the buckling of steel plates and the detachment of lining. Moreover, the study thoroughly examines and compares the friction and temperature behavior under the high load conditions applied to these three friction systems. Concurrent temperature measurements enable the establishment of robust temperature-based criteria for predicting and understanding damage behavior. [ABSTRACT FROM AUTHOR]

This paper describes the metrological procedure carried out for the evaluation of the building influence on air temperature measurements. This evaluation aims to produce reliable conclusions, information, and data to contribute to the WMO siting classification schemes for air temperature measurements. For this purpose, a field experiment was designed, deployed, and carried out. As a result, one-year-lasting air temperature measurements were collected and analyzed. In this field experiment, a 200 m wide building is the unique artificial heat source and the unique object projecting shades over a flat surface (no discernible slope) in an open space bigger than 40,000 m2, covered with short grass. Eight calibrated thermometers, equipped with the same model of artificially ventilated radiation shields, were set up at a height of 1.5 m from the ground and at different distances from a 200 m wide building. This configuration provides the observation of the horizontal air temperature radially distributed from the building and, as a conclusion, it enables the quantification of the building influences on air temperature measurements at different distances from the building. This document describes the field experiment, the analysis procedure, the evolution of the building influence on air temperature measurements along the day, and the impact of other meteorological parameters on this building effect. Two different building effects are observed: the positive building effect, where the air temperature decreases with the distance to the building, and the negative building effect, where the air temperature increases with the distance to the building. It is also noticed that the building influence is higher on clear days and the daily maximum building influence values are directly linked with the corresponding maximum solar irradiance. The influence of wind on the building effect is also analyzed, reaching the conclusion that due to characteristic of local winds, in terms of low speed and direction, the wind impact could be considered as negligible. The maximum values of building influence on air temperature measurements, the associated uncertainty analysis, and the conclusions are presented in this paper. All these points have been addressed using metrological principles with the purpose of giving consistency and robustness to the evidence presented here. [ABSTRACT FROM AUTHOR]