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Number of results: 167
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Abstract

By simulating the actual working conditions of a cable, the temperature variation rule of different measuring points under different load currents was analyzed. On this basis, a three-dimensional finite element model (FEM) was established, and the difference and influence factors between the simulation temperature and the experimental measured value were discussed, then the influence of thermal conductivity on the operating temperature of the conductor layer was studied. Finally, combined with the steady-state thermal conductivity model and the experimental measured data, the relation between thermal conductivity and load current was obtained.
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Abstract

This paper describes the weather conditions on the NE coast of Sørkappland (South Spitsbergen) during August 2005, and considers them in the context of the general synoptic situation over the North Atlantic . A comparison of local climates features for the East and West coast of southern Spitsbergen shows that the general atmospheric circulation and direct solar radiation in summer are the decisive factors affecting weather on the East coast. Foehn effects were observed during the study period. In the East, these were triggered by the westerly cyclonic situation and, in the West, by the easterly. The differences in the intensity of foehn effects may be explained by a specific relief of the Sørkappland peninsula.
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Abstract

The occurrence of coreless winters in the South Shetland Islands region is related to increase in the intensity of cyclonic circulation and to the presence of massive and rapid advection of warm air northerly and westerly. Coreless winter developments depend on large-scale oceanic processes – the presence of positive anomalies in sea surface temperature (SST) in the Bellingshausen Sea over the range 080°–092°W and the retreat of sea ice extent southwards. When negative anomalies of SST in the same region are observed and the sea ice extent advances northwards, a winter with clearly marked cold core is experienced at the Arctowski Station on the South Shetlands.
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Abstract

Ground temperature variations have been analysed to the depth of 160 cm, with respect to meteorological elements and short-wave radiation balance. The database of the ground temperature covers a thirteen month-long period (May 1992 – June 1993), which included both the seasons of complete freezing of the ground and thaw. Special attention has been given to the development of perennial permafrost and its spatial distribution. In summer, the depth of thawing ground varied in different types of ground — at the Polish Polar Station, this was ca. 130 cm. The ground froze completely in the first week of October. Its thawing started in June. The snow cover restrained heat penetration in the ground, which hindered the ground thawing process. Cross-correlation shows a significant influence of the radiation balance (K*) on the values of near-surface ground temperatures (r2 = 0.62 for summer).
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Abstract

The article describes the methodology for the determination of ambient temperature for thermovision measurements. The adopted methodology consists in the use of the technical blackbody model. Determining the value of the ambient temperature parameter makes it possible to enhance the accuracy of temperature measurement of objects exposed to strong irradiation using a thermovision camera.
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Abstract

The paper presents the method of on-line diagnostics of the bed temperature controller for the fluidized bed boiler. Proposed solution is based on the methods of statistical process control. Detected decrease of the bed temperature control quality is used to activate the controller self-tuning procedure. The algorithm that provides optimal tuning of the bed temperature controller is also proposed. The results of experimental verification of the presented method is attached. Experimental studies were carried out using the 2 MW bubbling fluidized bed boiler.
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Abstract

Candona rectangulata is an ostracod species common in cold (<15 ° C ) shallow freshwater Arctic water bodies. This species is useful in palaeolimnological studies because only few known autecological data can be applied in reconstructions of palaeoclimate. Particular attention was paid to the temperature, which is the basic factor determining the geo− graphic range of a species. In this study a wide tolerance of C. rectangulata to the temperature was demonstrated for the first time. Its high tolerance to the temperature changes seems to be based on induction of set of proteins belonging to the family of heat shock proteins. Using PAGE−SDS electrophoresis variation in the protein profile of non−model organism undergoing stress in the field (South Spitsbergen, near Stanisław Siedlecki Polish Polar Station) and in laboratory cultures was presented. These results could explain the eurythermic range of C. rectangulata and its good adaptation to the environmental conditions which normally do not exist in Arctic freshwater ponds.
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Abstract

Many Antarctic marine benthic invertebrates are adapted to specific environ− mental conditions (e.g. low stable temperatures, high salinity and oxygen content). Changes caused by global climatic shifts can be expected to have significant impact on their physiol− ogy and distribution. Odontaster validus, an ubiquitous, omnivorous sea star is one of the “keystone species” in the Antarctic benthic communities. Laboratory experiments were car− ried out to study the effect of temperature rise (from 0 to 5#2;C) on some vital biological func− tions that sea stars must perform in order to survive in their environment. Parameters such as behavioural reaction of sea stars to food and food odour, locomotory performance and abil− ity to right were measured. Temperature increase significantly impaired the ability of O. validus to perform these functions (e.g. lowering the number of sea stars able to right, in− creasing time−to−right, reducing locomotory activity, weakening chemosensory reaction to food and food odour). At temperatures of 4 and 5#2;C a loss of motor coordination was ob− served, although at all tested temperatures up to 5#2;C there were single individuals perform− ing successfully.
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Abstract

The theoretical aspects of a new type of piezo-resistive pressure sensors for environments with rapidly changing temperatures are presented. The idea is that the sensor has two identical diaphragms which have different coefficients of linear thermal expansion. Therefore, when measuring pressure in environments with variable temperature, the diaphragms will have different deflection. This difference can be used to make appropriate correction of the sensor output signal and, thus, to increase accuracy of measurement. Since physical principles of sensors operation enable fast correction of the output signal, the sensor can be used in environments with rapidly changing temperature, which is its essential advantage. The paper presents practical implementation of the proposed theoretical aspects and the results of testing the developed sensor.
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Abstract

Pulse electrochemical machining (PECM) provides an economical and e.ective method for machining high strength, heat-resistantmaterials into complex shapes such as turbine blades, die, molds and micro cavities. Pulse Electrochemical Machining involves the application of a voltage pulse at high current density in the anodic dissolution process. Small interelectrode gap, low electrolyte .ow rate, gap state recovery during the pulse o.-times lead to improved machining accuracy and surface .nish when compared with ECM using continuous current. This paper presents a mathematical model for PECM and employs this model in a computer simulation of the PECM process for determination of the thermal limitation and energy consumption in PECM. The experimental results and discussion of the characteristics PECM are presented.
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Abstract

The article discusses changes in Polish regulations concerning assessment of the climate hazard in underground mines. Currently, the main empirical index representing the heat strain, used in qualification of the workplace to one of the climate hazard levels in Poland is the equivalent climate temperature. This simple heat index allows easy and quick assessment of the climate hazard. To a major extent, simple heat indices have simplifications and are developed for a specific working environments. Currently, the best methods used in evaluation of microclimate conditions in the workplace are those based on the theory of human thermal balance, where the physiological parameters characterising heat strain are body water loss and internal core temperature of the human body. The article describes the results of research on usage of equivalent climate temperature to heat strain evaluation in underground mining excavations. For this purpose, the numerical model of heat exchange between man and his environment was used, taken from PN-EN ISO 7933:2005. The research discussed in this paper has been carried out considering working conditions and clothing insulation in use in underground mines. The analyses performed in the study allowed formulation of conclusions concerning application of the equivalent climate temperature as a criterion of assessment of climate hazards in underground mines.
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Abstract

In general, Antarctic marine bacteria are small, with biovolumes ranging from 0.139 to 0.204 μm-3 cell-1, but their total biomass in seawater is considerable due to relatively high numbers that approximate to 1020 cells km-3. Bacterial biomass becomes more concentrated closer to land. Our multi-year Antarctic studies demonstrated an average total bacterial biomass of 504 tons in Admirality Bay (24 km3) or 21 tons per 1 km3, versus 6.4 tons per 1 km3 in the open ocean. Strikingly, bacterial biomass reached 330 tons per 1 km3 of seawater at the sea-ice edge, as sampled in Goulden Cove in Admiralty Bay. Bacterial biomass in Admirality Bay, which we believe can be enriched by halotolerant and thermotolerant fresh water bacteria from glacial streams, is equal to or even exceeds that of the standing stock of krill (100-630 tons per bay) or other major living components, including phytoplankton (657 tons), flagellates (591 tons), and ciliates (412 tons). However, the bacterial biomass is exceeded by several orders of magnitude by non-living organic matter, which constitutes the basic bacterial carbon source. Factors regulating high bacterial abundance in the vicinity of land are discussed.
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Abstract

To investigate the effect of different proximate index on minimum ignition temperature(MIT) of coal dust cloud, 30 types of coal specimens with different characteristics were chosen. A two-furnace automatic coal proximate analyzer was employed to determine the indexes for moisture content, ash content, volatile matter, fixed carbon and MIT of different types of coal specimens. As the calculated results showed that these indexes exhibited high correlation, a principal component analysis (PCA) was adopted to extract principal components for multiple factors affecting MIT of coal dust, and then, the effect of the indexes for each type of coal on MIT of coal dust was analyzed. Based on experimental data, support vector machine (SVM) regression model was constructed to predicate the MIT of coal dust, having a predicating error below 10%. This method can be applied in the predication of the MIT for coal dust, which is beneficial to the assessment of the risk induced by coal dust explosion (CDE).
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Abstract

Measurements were made of sediment characteristics, benthic microbial activity and optimum temperature for sulfate reduction at Signy Island, South Orkney Islands, Antarctica . There was little evidence to support any seasonal variation in oxygen penetration of surface sediments. Oxygen penetrated to only 1.5 to 3 mm throughout the year, despite bioturbation from a dense amphipod population. The distribution of acid volatile sulfides increased with depth below 1 cm and above this, surface sediments were lighter in colour and contained fewer sulfides. The rates of sulfate reduction increased during winter under sea-ice cover, and remained high after ice break up. Seasonal water temperature was relatively constant between –1.8 and 0.5°C. Optimum temperature for anaerobic sediment respiration was investigated using different substrates and was found to be in the range 17–27°C, suggesting that sulfate reducing bacteria are psychrotolerant as they were inhibited by low temperatures.
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Abstract

This paper presents the first results of measurements of global solar radiation, albedo, ground surface and 2−m air temperature, relative humidity, and wind speed and direction carried out in the central part of Spitsbergen Island in the period 2008–2010. The study site was located on the coastal ice−free zone of Petuniabukta (north−western branch of Billefjorden), which was strongly affected by local topography, character of the ground surface, and sea ice extent. Temporal analysis of the selected meteorological parameters shows both strong seasonal and inter−diurnal variation affected by synoptic−scale weather systems, channelling and drainage effects of the fjords and surrounding glaciers. The prevailing pattern of atmospheric circulation primarily determined the variation in global solar radiation, wind speed, ground surface and 2−m air temperatures. Furthermore, it was found that thermal differences between Petuniabukta and the nearest meteorological station (Svalbard Lufthavn) differ significantly due to differences in sea ice concentrations and ice types in the fjords during the winter and spring months.
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Abstract

The paper presents the properties of a strain sensor, which was made using the micro hole collapse method and operates in the configuration of a Mach-Zehnder modal interferometer with a PM-1550-01 polarization maintaining photonic crystal fibre. The sensor’s transfer curve was determined analytically. Its strain sensitivity, determined from measurements, decreases slightly with increasing wavelength and is in a range from 􀀀2:01 to 􀀀2:23 pm/me in the wavelength range 1520–1580 nm. Based on the Fourier analysis of the wavelength spectrum of the constructed sensor, the difference of the group refractive indices of the core and the cladding of the photonic crystal fibre was determined, which are in a range from 7:45#1;10􀀀3 to 1:01#1;10􀀀2. The temperature sensitivity of the sensor, determined on the basis of measurements performed in a range from 23 to 60◦C, is positive and equals 5.9 pm/K.
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Abstract

In this study, weather conditions causing warm waves in north−western Spits − bergen, exemplified by Ny− Å lesund station, were analyzed. Between 1981 and 2010, 536 days with the maximum temperature exceeding 8.3 ° C (the value of 95 percentile) were selected. 37 warm waves, which altogether lasted 268 days, were identified. A typical feature of pressure pattern causing warm waves was the appearance of positive anomalies of both the sea level pressure and the height of isobaric surface 500 hPa in the Euro−Atlantic sector of the Arctic. This indicates a presence of high−pressure systems in this region. Extremely warm days appeared more often with the circulation from the eastern than the western sector. Longer and warmer heat waves occurring in the last decade of the analyzed period may be considered as a sign of climate warming, which has a significant impact on environment, i.e. reduction in area and thickness of glaciers, reduction of permafrost and snow cover, changes in biodiversity, etc . The increase in the air temperature and more frequent occurrence of heat waves may encourage development of tourism in polar areas, potentially causing further changes in the environment.
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Abstract

The paper analyzes the phenomenon of heat transfer and its inertia in solids. The influence of this effect on the operation of an integrated circuit is described. The phenomenon is explained using thermal analogy implemented in the Spice environment by an R-C thermal model. Results from the model are verified by some measurements with a chip designed in CMOS 0.7 μm (5 V) technology. The microcontroller-based measurement system structure and experiment results are described.
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Abstract

The paper deals with circuits, composed of bipolar transistors, diodes, resistors and independent voltage sources, having multiple DC solutions. An algorithm for tracing temperature characteristics, expressing the output signal in terms of the chip temperature, is developed. It is based on the efficient method for finding all the DC solutions sketched in this paper. The algorithm gives complete characteristics which are multivalued and usually composed of disconnected branches. On the other hand the characteristics provided by SPICE are fragmentary, lose some branches or exhibit apparent hysteresis.
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Abstract

This paper presents the results of measurements of the operation of a photovoltaic system, connected to the power grid. The intensity of solar radiation and the ambient temperature in the location of the installation were simultaneously recorded in different weather conditions on selected days throughout the year. For the combined results the analysis of correlation in terms of efficiency of individual exemplary photovoltaic installation was conducted.
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Abstract

This article presents the validation process of a brake FE model by means of temperature measured on a special stand using infrared technology. Unlike many other publications, the authors try to show the interaction between measurement technology and numerical modeling rather than only nice, perfectly correlated graphs. Some difficulties in choosing and using validation parameters are also pointed out and discussed. Finally, results of FE analyses are compared with measured data, followed by explanation of applied numerical technology and estimation of validation process effectiveness.
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Abstract

Open-Path Fourier Transform Infrared OP-FTIR spectrometers are commonly used for the measurement of atmospheric pollutants and of gases in industrial processes. Spectral interpretation for the determination of gas concentrations is based on the HITRAN database line-by-line modeling method. This article describes algorithms used to model gas spectra and to determine gas concentration under variable temperatures. Integration of individual rotational lines has been used to reduce the impact of spectrometer functions on the comparison of both measured and synthetic modeled spectra. Carbon monoxide was used as an example. A new algorithm for gas concentration retrieval consisting of two ensemble methods is proposed. The first method uses an ensemble of local models based on linear and non-linear PLS (partial least square) regression algorithms, while the second is an ensemble of a calibration set built for different temperatures. It is possible to combine these methods to decrease the number of regression models in the first ensemble. These individual models are appropriate for specific measurement conditions specified by the ensemble of the calibration set. Model selection is based on comparison of gas spectra with values determined from each local model
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Abstract

Objective: The aim of this study was to verify if the exposure to the pulsed electromagnetic field (PEMF) infl uenced the release of proinfl ammatory cytokines from adipose-derived stem cells (ADSCs) of normal and overweight rats of various age and sex. Moreover, we compared body temperatures of normal-weight and overweight rats. Methods: ADSCs of Wistar rats were isolated from the subcutaneous area in females and paratesticular region in males, cultured and exposed to PEMF (7 Hz, 30 mT). Concentrations of proinflammatory cytokines were determined in rat sera and supernatant from ADSCs cultures exposed and non-exposed to PEMF. Body temperature (BT) was measured twice a week, using an infrared and rectal thermometer. Results: Irrespective of age and sex, animals maintained on low-fat (LF) diet had higher BT than those grown on high-fat (HF) diet. Exposure to PEMF reduced the release of TNF-α and enhanced the production of IL-6 in ADSCs cultures from female pups maintained on LF diet. In contrast, a decrease in IL-6 level was observed in PEMF-exposed ADSCs cultures from female pups grown on HF diet. A similar phenomenon, i.e. a post-exposure increase in IL-6 level was also observed in male pups fed with the LF diet. In the case of ADSCs cultures from adult rats maintained on an HF diet, either males or females, PEMF exposure contributed to a dramatic increase in TNF-α production. Conclusion: Our findings suggest that PEMF exposure may affect the production of proinflammatory cytokines in ADSCs cultures. The intergroup diff erences in BT may result from the presence of an underlying inflammation in obese rats.
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