Observed Temperature Difference Research Articles

Development and Economical Analysis of Innovative Parabolic Trough Collector Integrated Solar Still

Experimental setup of the integrated parabolic trough collector (PTC) with solar still was developed. PTC was designed considering the solar geometry and the physical laws of parabolic shape and the concentrators. Test were conducted at the location with latitude 19.9975ON and longitude 73.7898OE. Theoretical analysis was done using ray tracing and engineering equation solver (EES) software while designing the system. PTC system was developed with dimensions of 1.5 m length, 1 m width and a concentration ratio (CR) of 21.22. Theoretical thermal efficiency was predicted as 48.1% whereas experimental average thermal efficiency is observed as 42.76%. The observed temperature difference between the vapor and the glass cover is about 17 °C and between ambient air and vapor is about 24.4 °C. Maximum water temperature in the conventional solar still was 64.6 °C where as for the PTC coupled solar still was 74.4 °C. PTC coupled solar still is having averagely 37% higher production rate. This has definitely added an advantage because of the higher energy absorption rate compared with the conventional solar still. PTC coupled solar still system has nearly 35% more heat absorption. Total embodied energy of the system is around 896.875 kWh. Total capital cost of the system is Rs. 41300/-. Total annual output of pure water is around 3 L/Day. Estimated energy payback period is around 2.29 years and the total carbon credit earned is Rs. 2165.38 per year.

Exploration of Thermal Bridging Through Shrub Branches in Alpine Snow

AbstractIn the high Arctic, thermal bridging through frozen shrub branches has been demonstrated to cool the ground by up to 4°C during cold spells, affecting snow metamorphism and soil carbon and nutrients. In alpine conditions, the thermal conductivity contrast between shrub branches and snow is much less than in the Arctic, so that the importance of thermal bridging is uncertain. We explore this effect by monitoring ground temperature and liquid water content under green alders and under nearby alpine tundra in the Alps. During a January 2022 cold spell, the ground temperature at 5 cm depth under alders is 1.3°C colder than under alpine tundra. Ground water freezing under alders is complete, while water remains liquid under tundra. Finite element simulations reproduce the observed temperature difference between both sites, showing that thermal bridging does affect ground temperature also under Alpine conditions.

Oxidation of Ceramic Materials Based on HfB2-SiC under the Influence of Supersonic CO2 Jets and Additional Laser Heating.

The features of oxidation of ultra-high-temperature ceramic material HfB2-30 vol.%SiC modified with 1 vol.% graphene as a result of supersonic flow of dissociated CO2 (generated with the use of high-frequency induction plasmatron), as well as under the influence of combined heating by high-speed CO2 jets and ytterbium laser radiation, were studied for the first time. It was found that the addition of laser radiation leads to local heating of the central region from ~1750 to ~2000-2200 °C; the observed temperature difference between the central region and the periphery of ~300-550 °C did not lead to cracking and destruction of the sample. Oxidized surfaces and cross sections of HfB2-SiC-CG ceramics with and without laser heating were investigated using X-ray phase analysis, Raman spectroscopy and scanning electron microscopy with local elemental analysis. During oxidation by supersonic flow of dissociated CO2, a multilayer near-surface region similar to that formed under the influence of high-speed dissociated air flows was formed. An increase in surface temperature with the addition of laser heating from 1750-1790 to 2000-2200 °C (short term, within 2 min) led to a two to threefold increase in the thickness of the degraded near-surface area of ceramics from 165 to 380 microns. The experimental results indicate promising applications of ceramic materials based on HfB2-SiC as part of high-speed flying vehicles in planetary atmospheres predominantly composed of CO2 (e.g., Venus and Mars).

INFRARED THERMOGRAPHY - COMPARISON OF INNER CANTHUS OF THE EYES AND FOREHEAD SURFACE TEMPERATURES IN HEALTHY ADULTS

Infrared thermography (IRT) is a non-invasive method for surface temperature measuring. The use of the contactless IRT method is comfortable for the patient, fast and hygienic. However, this method does not provide information about the core body temperature because the temperature is measured indirectly from the surface of the human body. There are several places on a human body from which surface temperature is commonly measured; the methods of measurement and application of the device is inconsistent. The aim of this article is to show the difference between the temperature measured on the forehead and on the inner corner of the eye in healthy persons, with reference to the recommendations of ISO standard. This is mainly due to the fact that compliance with the ISO standard is not always met, as shown by the personal experience of the authors. The body surface temperature was measured by use infrared camera WIC 640 under control of calibrated model of a black body. The data from 59 different volunteer subjects show statistically significant difference in measured temperature from both selected positions. The obtained median temperature values were 35.04 °C from forehead area and 35.85 °C from canthus of eyes. The observed difference was more than three-quarters of a degree Celsius for the median value. The maximum observed temperature difference within the observed group was almost 1.94 °C. The present study defines surface temperature from canthus of eye and undoubtedly shows how important it is to comply with the standards and recommendations of professional thermology societies.

In Situ Measurements of Thermal Ion Temperature in the Martian Ionosphere.

In situ measurements of ionospheric and thermospheric temperatures are experimentally challenging because orbiting spacecraft typically travel supersonically with respect to the cold gas and plasma. We present O2+ temperatures in Mars' ionosphere derived from data measured by the SupraThermal And Thermal Ion Composition instrument onboard the Mars Atmosphere and Volatile EvolutioN spacecraft. We focus on data obtained during nine special orbit maneuvers known as Deep Dips, during which MAVEN lowered its periapsis altitude from the nominal 150 to 120 km for 1 week in order to sample the ionospheric main peak and approach the homopause. We use two independent techniques to calculate ion temperatures from the measured energy and angular widths of the supersonic ram ion beam. After correcting for background and instrument response, we are able to measure ion temperatures as low as 100 K with associated uncertainties as low as 10%. It is theoretically expected that ion temperatures will converge to the neutral temperature at altitudes below the exobase region (∼180–200 km) due to strong collisional coupling; however, no evidence of the expected thermalization is observed. We have eliminated several possible explanations for the observed temperature difference between ions and neutrals, including Coulomb collisions with electrons, Joule heating, and heating caused by interactions with the spacecraft. The source of the energy maintaining the high ion temperatures remains unclear, suggesting that a fundamental piece of physics is missing from existing models of the Martian ionosphere.

Diagnosing pulsar winds in black-widow, redback, and other binary millisecond pulsar systems

ABSTRACTBinary systems composed of a recycled millisecond pulsar and a stellar companion in close orbit could be excellent sites to diagnose pulsar winds. In such systems, the pulsar outflow irradiates and heats up the companion atmosphere, which can lead to the observation of strong day/night modulations in temperature. We demonstrate with particle shower simulations that the particle energy of the wind affects the heating depth in the atmosphere: the wind heat can be deposited above or below the photosphere, leading to different signatures in the observed spectra. We apply our method to four specific systems: We find that systems with cool night-side companions showing strong temperature variations can give interesting lower limits on the particle energy in the winds. In particular, if the companion night side of PSR B1957+20 were to be suddenly irradiated, deep heating would only take place if particles with energy >100 TeV were present. Observational evidence of deep heating in this system thus suggests that (i) such particles exist in the pulsar wind and/or (ii) binary evolution non-trivially takes the companion to the observed temperature asymmetry. Besides, the observed temperature difference can be maintained only with particle energies of the order of 100 MeV.

Response of Surface Temperature to Afforestation in the Kubuqi Desert, Inner Mongolia

AbstractIn this study, micrometeorological observations in a shrub ecosystem and an adjacent poplar plantation forest ecosystem in the Kubuqi Desert, Inner Mongolia, China, are used to evaluate the theory of intrinsic biophysical mechanism (IBPM) and to investigate the biophysical effects of afforestation. Results indicate that after forcing energy balance closure to the observed fluxes, the IBPM theory agrees very well with the observed temporal variations in the surface temperature and with the observed temperature difference between the paired sites at the half‐hourly time scale. Afforestation activity in this dryland landscape has a cooling effect (−0.5 ± 0.2 K) in the daytime in all the seasons and a warming effect (0.2 ± 0.1 K) in the nighttime during the winter, spring and, autumn but a cooling effect (−1.0 ± 0.3 K) in the summer at night. These temperature changes are decomposed into contributions from changes in surface albedo, surface roughness, Bowen ratio, and ground heat flux. Comparison is made between the IBPM theory and the theory of the decomposed temperature metric.

New Type of Valve for Solar Thermal Storage Tank Stratification

This paper describes the working principle and characteristics of a new type of valve with a unique self-actuating principle that actuates based on observed temperature difference, which is intended for use on solar thermal storage tank inlets, where it compares the temperature of the flow coming into the valve with the temperature inside the storage tank, and switches the flow based on the observed temperature difference, in order to achieve maximum thermal stratification inside the storage tank. The novel working principle, based on mass-transfer inside the actuator driven by vapour pressure differences, is explained in detail, and results of tests with the valve are presented, which show that the valve switches very effectively, and is a very useful tool for storage tank stratification.

Detection of an observed 135 year ocean temperature change from limited data

AbstractRecent work comparing historical hydrographic data with modern Argo observations shows a long‐term change in the global ocean temperature. The magnitude of this change is greater than estimates of late 20th century warming, and implies a century‐scale change in the global oceans. Using global coupled climate models from the Coupled Model Intercomparison Project Phase 5 suite of simulations, we assess to what extent this observed temperature difference can be attributed to a genuine long‐term warming trend. After accounting for natural variability and sampling errors, we find convincing evidence that there has indeed been a century‐scale anthropogenic warming of the global ocean up to the present day, and a strong possibility of anthropogenic warming from 1873 to 1955. The estimated 1873–1955 ocean warming implies a net top‐of‐atmosphere energy imbalance of 0.1 ± 0.06 Wm–2, and a thermosteric global mean sea level rise of 0.50 ± 0.2 mma–1.

A Randomized Study of the Efficacy and Safety of Intravenous Acetaminophen Compared to Oral Acetaminophen for the Treatment of Fever

The purpose of this study was to assess the safety and dynamics of the onset of antipyretic efficacy of intravenous (IV) acetaminophen versus oral (PO) acetaminophen in the treatment of endotoxin-induced fever. This randomized, double-blind, double-dummy, single-dose study was conducted at a single center in the United States in healthy volunteer adult males with an endotoxin-induced fever to assess the antipyretic efficacy and safety of IV acetaminophen 1 g versus PO acetaminophen 1 g over 6 hours. Subjects who achieved a sufficient fever response to a test dose of reference standard endotoxin were randomly assigned to receive either IV acetaminophen and PO placebo (n = 54) or PO acetaminophen and IV placebo (n = 51). The primary efficacy outcome was the weighted sum of temperature differences from baseline at time T0 through T120 minutes. Safety evaluations included adverse event (AE), physical exam, and laboratory assessments. Of 105 subjects receiving study medication, 24 vomited within 2 hours postdose (PO acetaminophen, n = 15; and IV acetaminophen, n = 9) and were excluded from the modified intent-to-treat population that consisted of 36 and 45 subjects treated with PO and IV acetaminophen, respectively. While this was done to not confer an advantage to the IV formulation, a sensitivity analysis including these subjects did not change the overall efficacy results. Statistically significant results favoring IV acetaminophen were observed for the primary endpoint (weighted sum of temperature differences over 120 minutes, p = 0.0039) and also at each time point from T30 to T90 minutes, although the maximum mean observed temperature difference was only 0.3°C. The study drugs were well tolerated. The AE frequency was comparable between the IV and PO groups. A single dose of IV acetaminophen is as safe and effective in reducing endotoxin-induced fever as PO acetaminophen. IV acetaminophen may be useful where patients are unable to tolerate PO intake or when an earlier onset of action is desirable.

First Traction Results of High Spinning Large-Size Circular EHD Contacts from a New Test Rig: Tribogyr

This article presents a new test rig named Tribogyr and the first results obtained so far. This device allows EHL friction tests in rolling-sliding under high spinning conditions applied to large-size circular contacts. Spinning is imposed thanks to a unique design that includes a tilting facility of one of the two spindles. After a brief description of the test rig structure and of the specimen geometry, the sensor's implementation and the device capabilities are reported. The parameter used to quantify the spin in this study is then defined. It only takes into account the rotational speed normal to the contact surface and the contact radius. Then, the friction coefficient and the temperature measurements are presented. The data are at first plotted versus the classical slide-to-roll ratio and compared to numerical results obtained with and without spin. The spin parameter then is introduced to replace the slide-to-roll ratio as the varying parameter. This representation allows reporting all the results in the same figure, where the influence of the operating conditions like the entrainment speed, the tilting angle, and the slide-to-roll ratio on friction and on temperature is much more visible. It is discussed that the observed temperature difference increase is generated by an additional shearing introduced by spinning despite an observed reduction of friction.

Kaolin particle film associated with increased cotton aphid infestations in cotton

AbstractHighly reflective white kaolin‐based particle film was sprayed on cotton, Gossypium hirsutum L. (Malvaceae), plots in south Texas during 2004 and 2005 to observe its effect on the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae). Populations of cotton aphids on the ventral surfaces of leaves in the kaolin‐treated plots were greater than in non‐treated control plots during both years. Alate cotton aphids were attracted less to white than to other pan trap colors, and parasitism by Lysiphlebus spec. (Hymenoptera: Aphidiidae) was either unaffected or greater in the kaolin‐treated plots, hence these two factors (color and parasitism) do not explain the increased infestations in the treated plots. However, mean temperatures on the ventral surfaces of kaolin‐treated cotton leaves were cooler than those of control leaves. The observed temperature difference where cotton aphids reside on cotton leaves is a potential reason for the greater infestations in the kaolin treatment plots. Our study demonstrates that applications of kaolin can exacerbate a pest infestation in cotton.

Ecology of an exceptional roost: Energetic benefits could explain why the bat Lophostoma silvicolum roosts in active termite nests

The ability to create shelters that provide protection from the environment is widespread among animals. However, in spite of the central role roosts play in the life of bats (Chiroptera), only a few species have developed the ability to make their own refuges, one of them being the Neotropical Lophostoma silvicolum. This bat creates and inhabits cavities in active arboreal nests of the termite Nasutitermes corniger. We measured temperature in cavities inside active and dead termite nests, and in tree holes occupied by closely related bats, to determine whether energetic benefits compensate for the cost of excavating the hard nests. The inside temperatures of active termite nests were very stable and 2.1–2.8 °C warmer than those of the other two potential roost types. The observed temperature difference is estimated to allow euthermic L. silvicolum to save about 5% of their daily energy expenditure when roosting in active termite nests instead of dead nests or tree holes. Suitable roosting conditions result from the presence of termites and are independent of nest architecture. Our results indicate that the benefits of higher temperatures may be one of the driving forces promoting the evolution of active roost making in bats.

The global signal of the 11-year solar cycle in the stratosphere: observations and models

Earlier studies used the data from four solar cycles, to examine the global structure of the signal of the 11-year sunspot cycle (SSC) in the stratosphere and troposphere, using correlations between the solar cycle and heights and temperatures at different pressure levels. Here, this work is expanded in Part I to show the differences of geopotential heights and temperatures between maxima and minima of the SSC. This study puts the earlier work on a firmer ground and gives quantitative values for comparisons with models. In Part II, two general circulation models (GCMs) with coupled stratospheric chemistry are used to simulate the impact of changes in solar output. This paper is not intended as a review of the whole topic of solar impacts, but provides some results recently obtained in observations and modelling. Comparisons between the GCM results and observations show that the differences between solar maximum and solar minimum for temperature and ozone are generally smaller than observed. In the middle and upper stratosphere, models are closer to agreeing with observations of temperature, but a significant observed temperature difference near 100 hPa is not reproduced in the models. Also, model predictions of the shape of the vertical profile of the ozone difference do not agree with observations and the comparisons are hindered by large statistical uncertainties in both models and observations. Nonetheless, the results are an improvement on 2-D model results in showing a larger ozone signal in the lower stratosphere.

Observation and simulations of winds and temperatures in the Antarctic thermosphere for August 2–10, 1992

Optically derived upper thermospheric wind and temperature data, collected at Antarctic stations at South Pole (L = 14), Mawson (L = 9.3), and Halley (L = 4.6), and averaged over the low‐activity period August 2–10, 1992, have been interpreted with the help of simulation by the National Center for Atmospheric Research thermosphere ionosphere electrodynamic general circulation model (TIEGCM) with inputs matching the average conditions of observation. The simulation provides a global background context upon which the widely‐separated optical observations can be placed. The simulation shows three large‐scale structures in the polar wind field: the morning vortex, the evening vortex, and the cross‐polar wind jet. Each of these came within view of the group of observing stations during the diurnal cycle, providing arrival time observations and signatures which were examined relative to the TIEGCM simulation. Reasonable correspondence was found, indicating the capability of the model to agree simultaneously with observations at three widely spaced stations representative of the subauroral and auroral zones, as well as the polar cap. Simulated wind directions were in excellent agreement with observation, although wind magnitudes frequently exceeded measured values by up to 30%. Apparent divergent flows in the data from Halley and Mawson were explained as signatures of vortices from their presence in the simulated wind fields. Observed diurnal mean temperatures compared well with the simulation, confirming that heat inputs and the distribution of thermal energy in the model are, on average, reasonable. A significant and persistent difference between experimental and modeled temperatures was that the diurnal temperature variation observed at South Pole peaked at the nightside crossing of the jet and was minimum a few hours before noon magnetic local time, whereas the simulation indicated minimum temperatures on the nightside, in antiphase to the measurements. A simple calculation indicates that the observed temperature difference between the air parcels entering the polar cap, encountered on the dayside, and those leaving the polar cap on the nightside is reasonably matched to the heating due to the ion‐drag acceleration process. No explanation of the lack of this temperature rise in the TIEGCM simulation is presently available.

Observation of intense sunglint in 3.7 mum channel of the AVHRR

In strong sunglint areas the brightness temperatures in channel 3 (3.7 mu m) and channel 4 (11 mu m) of the Advanced Very High Resolution Radiometer (AVHRR) have been found to differ by more than 27 degK. In the worst case, where there is a large amount of water vapour, as in the tropics, the difference in atmospheric effects in these two channels is only about 3 degK. Therefore, most of the observed temperature difference must be due to specular reflection of the solar radiation. Although detection of intense sunglint has been reported by others their analysis was in terms of digital numbers which cannot reveal if the detector is saturated. Using brightness temperatures rather than digital numbers, it is shown that the magnitude of sunglint contribution cannot be fully quantified because the 3.7 mu m sensor is saturated. There are two independent lines of evidence which show the saturation of the detector: ( i ) In the absence of sunglint there is a periodic noise in channel 3 of the NOAA-7 AVHRR which disappears in the strong sunglint zone and, ( ii ) the sunglint contributions in channel 1 (0.63 mu m) and channel 2 (0.93 mu m) of the AVHRR change in those areas where the sunglint in the 3.7 mu m channel remains constant. The observed saturation temperature is about 319 degK, whereas that calculated from the inflight calibration parameters is about 323degK. Assuming that the inflight calibration information is reliable, this discrepancy in the saturation temperature is explained by proving that the full quantization range of 0 to 1023 is not utilized. Therefore, saturation of the detector cannot be ascertained from the values of digital numbers.

Origin of microstructure in Bi–Pb and Bi–Sn binary eutectics

To study in detail the nature of the advancing solid/liquid interface, thin specimens of the binary eutectic alloys Bi-Pb2 Bi and Bi-Sn were solidified at various low speeds (5.7–115 nm S−1) and quenched to form a representative interface for subsequent examination. Both eutectic alloys were found to be of the faceted-non-faceted type, with Bi the faceting phase. The solid/liquid interface was observed to be nearly planar and isothermal at the lowest growth rate used, but became increasingly irregular and non-isothermal with increasing growth rate. The maximum observed temperature difference between the most and least advanced parts of the interface was estimated to be ∼ 1 K. Massive Bi particles were formed at the lowest growth rate. Although still recognisable in outline, these Bi regions became subdivided at higher growth rates. An extracted particle of subdivided Bi was shown to be a single crystal. In the case of the Bi-Sn eutectic alloy, at the higher growth rate used, two phase projections were sometimes observed to form on the interface, indicating the presence of a layer of liquid undercooled with respect to both phases. An explanation is proposed to account for the formation of this layer.

Inferring Density from Temperature via a Density-Ratio Relation

A method is presented for determining salinity and density from temperature data in conjunction with historical or contemporaneous (but not collocated) CTD observations. The horizontal density ratio r(z) is determined from the temperature and salinity differences at each depth (δT, δS) between pairs or ensembles of profiles. These differences are expressed as a density ratio r=αδT/βδS, where α and β are the expansion coefficients for temperature and salinity, respectively. Salinity at a site where only temperature is measured, as with an expendable bathythermograph (XBT), is computed based on the temperature and salinity at a reference station (SR,TR); that is, S=SR+(T−TR)δS/δT. The method is restrictive in its application because it is most accurate when all water masses in the region of a survey are linear extrapolations from the water masses at each of the reference stations. In reality, it provides useful results when the T and S fields are not simply linear functions of horizontal distance. This approach is particularly useful in regions where, the T(z)−S(z) relation is nonunique, as in the Mediterranean Water in the North Atlantic. The corresponding expression for the lateral density difference for an observed temperature difference (δT) is δρ=−αρ0δT(1−r−1). Observations from regions offshore and along the coast of Portugal are used to evaluate the method. Errors of less than 0.05 psu are exhibited in the evaluation of salinity determined from T-5 XBT drops compared with nearly simultaneous CTD casts. A comparison of water properties and cyclostrophic velocities is made using XCP temperatures and XCP velocities in a meddy.

Thermoanalytical study of the methyl methacrylate polymerization under thermal gradient

Cylindrical samples of thermally polymerized methylmethacrylate (MMA) were investigated and the time dependent temperatures at certain positions within the samples were measured during this process. Owing to the polymerization heat evolved, the maximal observed temperature difference within this probe was ΔT = 3.5°C, e.g. the MMA polymerization occurs under a thermal gradient. As a consequence, the maximal difference at the glass transition temperature of the solid PMMA is ΔT g = 1.5°C, and for samples prepared at a higher temperature gradient (arranged by means of a central “hot wire”), ΔT g = 6°C. For this cross-sectional inhomogeneity, a difference in the molecular weight distribution for the annealed samples of ΔM = 3 × 10 4 is proposed.

Two-phase water heater: Model and long term performance

In the present study the model for the two-phase water heater proposed earlier is modified to account for diurnal variation of the heat transfer coefficient in the condenser. The present model is able to account for the observed temperature difference between the collector plate and storage water. The agreement with experimental results is good when liquid level in the collector is equal to or greater than 80%. This also ensures good performance of the heater. With lower liquid levels, as vapor superheating takes place, the condenser performance is affected resulting in poor performance of the water heater. The two-phase water heater was extensively tested over two years with and without hot water withdrawals. Its performance was compared with a thermosiphon water heater of identical collector area and storage volume. Weekly solar fractions for both the heaters are presented for a one year perios. It is found that the two-phase water heater is 4–8% less efficient than the thermosiphon water heater for clear sky and high radiation levels (22–28 MJ m −2 day −1). In monsoon, however, it is 40% less efficient due to low radiation level (12–15 MJ m −2 day −1). Low radiation level reduces vapor generation rate which significantly affects condenser performance.