Infrared Radiation

From the thermal point of view, windows represent the weak link between the internal and external ambients of a room. In cold climates, they are responsible for 10-25% of the heat lost from the heated ambient to the external atmosphere. In hot climates, the excessive solar radiation entering the internal ambient through the windows leads to increasing the cooling load of the refrigeration system. The use of absorbing gases filling the gap between glass sheets appears to be an alternative solution for thermally insulated glass windows. The other options one may incorporate filling materials such as silica aerogel or a PCM. In this work, a comparison between the thermal efficiency of two glass windows one filled with an absorbing gas and the other with a PCM and exposed to solar radiation in a hot climate is done. To model double glass window filled with infrared absorbing gases, a CW real gas model is used. A radiative convective conductive model and a radiative conductive model were investigated. Three mixtures of gases were used; a strongly absorbing gas mixture, an intermediate absorbing gas mixture and a transparent to infrared radiation mixture. To model the double glass window filled with a PCM, a relatively simple and effective radiation conduction one dimensional formulation is used. Heat transfer through the window is calculated and the total heat gain coefficients are compared and discussed.

We have developed a high flux source of low energy neutral beams to study the spacecraft glow phenomena by using a biased Umiter to neutralize plasma in ACT-1. Beams of nitrogen and nitrogen-oxygen mixtures with energies of 1 to 15 eV and fluxes £ 10 /cm /s were directed on target surfaces consisting of Z-302 and Z-306 paints. With the nitrogen beams we successfully detected a glow due to beam-surface interactions. In addition, we discovered a volume glow effect due to beam-gas interactions which may also play a role in spacecraft glow. DISCLAIMER employee*. mate My «m«ty, «**« "JXss 0 f any information, appuatus, product « W, rbHbc accur«y. «l»J^Sd »ot i«Ue privately wort **"£ ptoia diidowd. or reprewiU ""'."* i^. 'T or0 « ss> " service by trade name, trademark, S«in to «* *** T^nShr^S-. or imply its «*""?* "^ awAcMcr. or other |* d~ "^^^ernment or any ageac, thereof TheVK« sstr^s-''£5trr-*-of ,te SjsXoovemmeat or any •*«*, <•-'• *X *»

This paper describes the technical features of four electro-optic sensors for the monitoring of arc welding. The energy released in the process determines the formation of a strongly radiative plasma in the interaction zone. The working principle of the prototype is based on the detection of visible, infrared and ultraviolet emission of the plasma. A discrimination algorithm has been found that allows the characteristics of the weld to be evaluated and to distinguish bad weldings from good ones. q

Page 1. Advanced pixel design for infrared 3D LADAR imaging Fabrice Guellec, Michaël Tchagaspanian Eric de Borniol, Pierre Castelein, André Perez, Johan Rothman CEA Leti – MINATEC, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France ABSTRACT ...

: An airborne hyperspectral imaging system named SYSIPHE is currently being developed by ONERA, France, under the contracting authority of the French MoD. This system will be dedicated to making absolute measurements of spectral radiances and emissivities of various ground scenes, in order to create an important ground hyperspectral data base. All the data collected will in turn be used in several defense applications. The measurement part of SYSIPHE will be composed of two optical instruments, together integrated into a DO-228 plane held by the German DLR. One of the instruments is working in the visible, near infrared and short wave infrared (SWIR) domains. It is named HySpex2 and is being developed by NEO and FFI, Norway. SIELETERS, being developed by ONERA, is the second one and is working in the medium wave infrared (MWIR) and long wave infrared (LWIR) domains. SIELETERS and HySpex2 will be integrated simultaneously above the plane hatch.

The angular distribution of infrared radiation, emitted by high efficiency single-crystalline silicon solar cells, was analyzed. Measurements were performed on cells with planar and inverted-pyramids surfaces, both showing integral emissions that approach the cosine function in the 0°-90°interval. Textured cell maintains the cosine distribution at the different wavelengths; planar device shows a distribution, which deviates from the cosine function at increasing wavelength. Correspondence between emission and absorption properties was demonstrated valid as a function of emission/ absorption angle. From the angular distribution of electroluminescence light, the devices absorption properties for incident light with directions different from the surface normal were estimated.

We measure infrared absorption spectra of 18 hydrochlorofluorocarbons and hydrofluorocarbons, seven of which do not yet appear in the literature. The spectra are used in a narrowband model of the terrestrial infrared radiation to calculate radiative forcing and global warming potentials. We investigate the sensitivity of the radiative forcing to the absorption spectrum temperature dependence, halocarbon vertical profile, stratospheric adjustment, cloudiness, spectral overlap, and latitude, and we make some recommendations for the reporting of radiative forcings that would help to resolve discrepancies between assessments. We investigate simple methods of estimating instantaneous radiative forcing directly from a molecule's absorption spectrum and we present a new method that agrees to within 0.3% with our narrowband model results. 1. Introduction Fully halogenated alkanes such as the chlorofluorocarbons (CFCs) and Halons are very useful industrial chemicals. For example, they are used as refrigerants, as solvents, as foamblowing agents, and as fire suppressants. Concern over stratospheric ozone depletion has led to tight controls on CFC and Halon production. Hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are possible substitutes. The choice of HFCs and HCFCs is motivated by a number of factors, not the least of which is that in contrast to CFCs, HFCs and HCFCs contain one or more C-H bonds. Hence HFCs and HCFCs are susceptible to attack by OH radicals in the troposphere and therefore have the important environmental advantage of a significantly shorter lifetime compared to the fully halogenated species. HFCs do not contain chlorine and so have no ozone depletion potential associated with the well-established chlorine catalytic cycles. While HCFCs contain chlorine, the delivery of this chlorine to the stratosphere is relatively inefficient because of the scavenging of HCFCs by OH radicals in the troposphere. To define the environmental impact of HFCs and HCFCs, their ability to destroy stratospheric ozone, produce noxious degradation products, and contribute to potential global warming must be assessed. The present work addresses the effect of HCFCs and HFCs on radiative forcing and hence potential global warming. For a review of the atmospheric chemistry of these species see Wallington et al. [1994]. In the following, all alkanes containing at least one halogen atom are referred to as "halocarbons," while the special cases of HCFCs and HFCs are referred to as "hydrohalocarbons." The radiative forcing issue arises because the halocarbons absorb strongly in the 500-1500 cm-• (7-20 gm) region of the

We discuss the effect of atmospheric dispersion on the performance of a mid-infrared adaptive optics assisted instrument on an extremely large telescope (ELT). Dispersion and atmospheric chromaticity is generally considered to be negligible in this wavelength regime. It is shown here, however, that with the much-reduced diffraction limit size on an ELT and the need for diffraction-limited performance, refractivity phenomena should be carefully considered in the design and operation of such an instrument. We include an overview of the theory of refractivity, and the influence of infrared resonances caused by the presence of water vapour and other constituents in the atmosphere. 'Traditional' atmospheric dispersion is likely to cause a loss of Strehl only at the shortest wavelengths (L-band). A more likely source of error is the difference in wavelengths at which the wavefront is sensed and corrected, leading to pointing offsets between wavefront sensor and science instrument that evolve with time over a long exposure. Infrared radiation is also subject to additional turbulence caused by the presence of water vapour in the atmosphere not seen by visible wavefront sensors, whose effect is poorly understood. We make use of information obtained at radio wavelengths to make a first-order estimate of its effect on the performance of a mid-IR ground-based instrument. The calculations in this paper are performed using parameters from two different sites, one 'standard good site' and one 'high and dry site' to illustrate the importance of the choice of site for an ELT.

Infrared (IR) remote sensors calibrated with propane understate volatile organic compound (VOC) concentrations in vehicle exhaust by 30-70% when compared to flame ionization detectors (FID). The difference depends on VOC composition and arises because many organic compounds in vehicle exhaust absorb less IR radiation than propane on a per-carbon basis. This study demonstrates an approach for scaling infrared measurements to reflect more accurately total exhaust VOC emissions from on-road motor vehicle fleets. Infrared versus flame ionization detector response to individual VOC was measured in the laboratory for methyl tert-butyl ether and a range of alkanes, alkenes, and aromatics that are prominent in vehicle exhaust. Overall IR/FID response to real exhaust mixtures was calculated by summing the response contributions of all individual VOC constituents. Average IR/FID response factors were calculated for typical onroad vehicle fleets based on VOC speciation profiles measured in several U.S. roadway tunnels. Results indicate that hydrocarbon concentrations measured by remote sensors with 3.4 µm filters should be multiplied by a factor of 2.0 ( 0.1 for light-duty vehicles using either California or federal reformulated gasoline blends and by 2.2 ( 0.1 when conventional gasoline is used.

LiNiPO 4 belongs to a family of olivine type compounds, with members LiMPO 4 where M = Fe, Mn, Co or Ni are transition metals. The lithium nickel phosphate was prepared and characterized in order to evaluate a new potential cathode material for our ongoing research in aqueous rechargeable batteries. Annealing the final product is critical in obtaining the stoichiometric LiNiPO 4 pure phase; conventional cooling to a room temperature leads to an indication of Li 3 PO 4 and NiO secondary phases as impurities. The synchrotron infrared radiation (SR-IR) as a source for IR spectroscopy pins down the differences in the chemical bonding for annealed and conventional cooled LiNiPO 4 samples. The cyclic voltammetric and galvanostatic studies showed annealed LiNiPO 4 is electrochemically active from which lithium ions can be de-intercalated during oxidation process leading to an amorphous NiPO 4 and a minor product of nickel(II) hydroxide (␤-NiOOH). During subsequent reduction, lithium ions are not fully intercalated, however, the structure is reversible and adequate for multiple cycles. The high potential in LiNiPO 4 looks to be very attractive in terms of high energy density, given the efficiency is improved.

This paper presents, in the context of materials dynamic behaviour study, a method for simultaneous measurement of the temperature and emissivity of a solid's surface, by the use of infrared radiation. In contrast to existing methods, this method has no need for a pre-measurement of the surface emissivity. The emissivity and the temperature are measured simultaneously, by detecting the variations of emitted radiation and infrared radiation reflecting on the surface, at two different spectral zones. In this way, the accuracy of the measured temperature is greatly improved in cases were the surface optical properties vary during the measurement. Several experiments were carried out in order to complete the theoretical foundation of the method and to outline its accuracy and some of its limitations. There are various industrial applications of this method, for example the control of the temperature of the mechanical parts during work machining. One of them may be the measurement of the temperature of a sample during mechanical testing. An application of the method is proposed, that is easy to employ with non-sophisticated infrared and optical components. The results confirm the accuracy of the proposed method with an order of 3% of precision for temperature determination.

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington headquarters Services, Directorate for Information Operations and Reports,

Spiral phase elements with topological charges based on space-variant Pancharatnam-Berry phase optical elements are presented. Such elements can be achieved by use of continuous computer-generated space-variant subwavelength dielectric gratings. We present a theoretical analysis and experimentally demonstrate spiral geometrical phases for infrared radiation at a wavelength of 10.6 mm.

Green areas in the urban environment can contribute to the mitigation of the Urban Heat Island. In a context of climate change, with the expected increase in temperature, dryness and intensity of heat waves, green areas assume even higher importance as they can create a cooling effect that extends to the surrounding areas. This study analyses the thermal performance of a small green space (0.24 ha) and its influence in the surrounding atmospheric environment of a densely urbanised area in Lisbon. Measurements of weather parameters (temperature, relative humidity, wind speed, solar and infrared radiation) were carried out along a selected path, starting from inside the green area to surrounding streets with different orientations and solar exposure. It was found that the garden was cooler than the surrounding areas, either in the sun or in the shade. These differences were higher in hotter days and particularly related to the mean radiant temperature (Tmrt). The highest difference found was of 6.9 C in relation to air temperature and 39.2 C in relation to Tmrt; in both cases this difference occurred between the shaded site inside the garden and the sunny site in an EeW oriented street in the southern part of the studied area. Besides the local weather conditions, particularly the low wind speed, the sun exposure and the urban geometry are the potential factors that explain these differences. The cooling effect of green areas on the surrounding environment can be enhanced by additional measures related to the urban features of each city.

A large number of water-and climate-related applications, such as drought monitoring, are based on spaceborne-derived relationships between land surface temperature (LST) and the normalized difference vegetation index (NDVI). The majority of these applications rely on the existence of a negative slope between the two variables, as identified in site-and time-specific studies. The current paper investigates the generality of the LST-NDVI relationship over a wide range of moisture and climatic/radiation regimes encountered over the North American continent (up to 608N) during the summer growing season (April-September). Information on LST and NDVI was obtained from long-term (21 years) datasets acquired with the Advanced Very High Resolution Radiometer (AVHRR). It was found that when water is the limiting factor for vegetation growth (the typical situation for low latitudes of the study area and during the midseason), the LST-NDVI correlation is negative. However, when energy is the limiting factor for vegetation growth (in higher latitudes and elevations, especially at the beginning of the growing season), a positive correlation exists between LST and NDVI. Multiple regression analysis revealed that during the beginning and the end of the growing season, solar radiation is the predominant factor driving the correlation between LST and NDVI, whereas other biophysical variables play a lesser role. Air temperature is the primary factor in midsummer. It is concluded that there is a need to use empirical LST-NDVI relationships with caution and to restrict their application to drought monitoring to areas and periods where negative correlations are observed, namely, to conditions when water-not energy-is the primary factor limiting vegetation growth.

This paper strongly suggests that the microwave rationale behind modern-day SETI lore is suspect, and that our search for electromagnetic signals from extraterrestrial technical civilizations may be doomed to failure because we are 'tuned to the wrong frequencies'. The old idea that lasers would be better for interstellar communications is revisited. That optical transmissions might be superior for CETI/SETI has generally been discounted by the community. Indeed, there is very little in the literature about the optical approach, as its efficacy was more or less dismissed by SETI researchers some twenty years ago. The main reason that the laser approach to SETI has been given a bad 'press' is the assumption that ETIs lack the skills to target narrow optical beams into selected stars. This assumption of ineptitude is shown to be erroneous, and calls into question some aspects of the rationale for Microwave SETI. The detectability of both continuous wave and pulsed visible/infrared laser signals is described in some detail.

Nanoantennas for visible and infrared radiation can strongly enhance the interaction of light with nanoscale matter by their ability to efficiently link propagating and spatially localized optical fields. This ability unlocks an enormous potential for applications ranging from nanoscale optical microscopy and spectroscopy over solar energy conversion, integrated optical nanocircuitry, opto-electronics and density-ofstates engineering to ultra-sensing as well as enhancement of optical nonlinearities.

Gas phase mid-infrared spectroscopy of molecular ions can nowadays be performed with high performance mass spectrometers coupled to free electron lasers (FEL). The wide and continuous tunability of highly intense FELs in the mid-infrared region can be exploited for performing infrared multiple photon dissociation (IRMPD) spectroscopy of molecular ions. This review will focus on gas phase IRMPD spectroscopic investigations aiming at probing the structure and the reactivity of transition metal complexes. The performance of infrared spectroscopy for characterizing the coordination mode of polydentate ligands and the spin state of the metal will be illustrated. Infrared spectroscopy has also been exploited to probe the reactivity of metal complexes, and a special attention will be given to the infrared spectroscopy of reactive intermediates. # 2007 Wiley Periodicals, Inc., Mass Spec Rev 26:583-605, 2007

Tropical soils are important sources and sinks of atmospheric methane (CH 4 ) and major sources of oxides of nitrogen gases, nitrous oxide (N 2 O) and NO x (NO+NO 2 ). These gases are present in the atmosphere in trace amounts and are important to atmospheric chemistry and earth's radiative balance. Although nitric oxide (NO) does not directly contribute to the greenhouse effect by absorbing infrared radiation, it contributes to climate forcing through its role in photochemistry of hydroxyl radicals and ozone (O 3 ) and plays a key role in air quality issues. Agricultural soils are a primary source of anthropogenic trace gas emissions, and the tropics and subtropics contribute greatly, particularly since 51% of world soils are in these climate zones.

Energy consumption for drying of mushroom slices was evaluated using various drying methods including hot air, microwave, vacuum, infrared, microwave-vacuum and hot air-infrared. Results of data analysis showed that the lowest and highest energy consumption levels in drying mushroom slices were associated with microwave and vacuum dryers, respectively. The use of vacuum in conjunction with microwave drying increased energy consumption relative to microwave drying alone. Energy consumption in the hot air dryer showed a downward trend with increasing temperature and an upward trend with increasing air velocity. In drying mushroom using infrared radiation, it was observed that increased air velocity increases drying time and consequently the amount of consumed energy. Using a combination of hot air and infrared drying decreased energy consumption relative to infrared drying alone and increased it relative to hot air drying. In the combined microwave-vacuum dryer, drying time and consequently energy consumption decreased in comparison to the vacuum dryer. Hot air-infrared drying of mushroom slices proved to have the lowest energy consumption.

SBDART is a software tool that computes plane-parallel radiative transfer in clear and cloudy conditions within the earth's atmosphere and at the surface. All important processes that affect the ultraviolet, visible, and infrared radiation fields are included. The code is a marriage of a sophisticated discrete ordinate radiative transfer module, low-resolution atmospheric transmission models, and Mie scattering results for light scattering by water droplets and ice crystals. The code is well suited for a wide variety of atmospheric radiative energy balance and remote sensing studies. It is designed so that it can be used for case studies as well as sensitivity analysis. For small sets of computations or teaching applications it is available on the World Wide Web with a user-friendly interface. For sensitivity studies requiring many computations it is available by anonymous FTP as a well organized and documented FORTRAN 77 source code.

From the time mechanical refrigeration was first introduced, its use has significantly increased. In general, cooling is achieved with vapor compression machines that use specific refrigerants (blends of hydrogen, carbon, fluorine and chlorine in various mixing ratios) that can be tailored to create cooling at any required temperature level. Each refrigerant exhibits a specific global warming potential and ozone depletion potential in the atmosphere by absorbing infrared radiation and breaking down of ozone molecules. Since the adverse effects of those substances have been discovered, the field of refrigeration has been moving away from conventional refrigerants, and searching for better alternatives. Thermoacoustic refrigeration is such an alternative that can provide cooling to essentially any required temperature level without using any environmentally harmful substances. It is presently a niche technology that can be expanded into a broader market, primarily if the sizing problem can be solved. Currently, the most efficient thermoacoustic refrigerators are used in industrial settings. This work explores the possibility of decreasing the footprint of these refrigerators by utilizing a coiled resonator. A CFD analysis has been developed and first results in regard to coiled resonators are shown and discussed.

Vein pattern recognition is one of the newest biometric techniques researched today. While the concept behind the method is quite simple, there are various challenges to be found throughout the design and implementation of a vein scanning device concerning the hardware lighting system and the actual algorithms used for processing the acquired images. In order to keep the scanning errors to a minimum the image acquired from the camera should be almost noiseless and the algorithms should be able to detect the vein pattern in various real life conditions. Many implementations of this method are now in a commercial phase and there is a great need for a system that can detect, analyze and extract the correct human vein pattern while keeping a low cost and reducing the computational needs of the image processing algorithms. This paper will offer some hardware implementation solutions based on our research and different algorithms will be discussed.

The low density of ions in mass spectrometers generally precludes direct infrared (IR) absorption measurements. The IR spectrum of an ion can nonetheless be obtained by inducing photodissociation of the ion using a high-intensity tunable laser. The emergence of free electron lasers (FELs) and recent breakthroughs in bench-top lasers based on nonlinear optics have now made it possible to routinely record IR spectra of gasphase ions. As the energy of one IR photon is insufficient to cause dissociation of molecules and strongly bound complexes, two main experimental strategies have been developed to effect photodissociation. In infrared multiple-photon dissociation (IR-MPD) many photons are absorbed resonantly and their energy is stored in the bath of vibrational modes, leading to dissociation. In the ''messenger'' technique a weakly bound van der Waals atom is detached upon absorption of a single photon. Fundamental, historical, and practical aspects of these methods will be presented. Both of these approaches make use of very different methods of ion preparation and manipulation. While in IR-MPD ions are irradiated in trapping mass spectrometers, the ''messenger'' technique is generally carried out in molecular beam instruments. The main focus of this review is the application of IR spectroscopy to biologically relevant molecular systems (amino acids, peptides, proteins). Particular issues that will be addressed here include gas-phase zwitterions, the (chemical) structures of peptides and their collision-induced dissociation (CID) products, IR spectra of gas-phase proteins, and the chelation of metal -ligand complexes. Another growing area of research is IR spectroscopy on solvated clusters, which offer a bridge between the gas-phase and solution environments. The development of state-of-the-art computational approaches has gone hand-inhand with advances in experimental techniques. The main advantage of gas-phase cluster research, as opposed to condensed-phase experiments, is that the systems of interest can be understood in detail and structural effects can be studied in isolation. It will be shown that IR spectroscopy of mass-selected (bio)molecular systems is now well-placed to address specific questions on the individual effect of charge carriers (protons and metal ions), as well as solvent molecules on the overall structure. #

BACKGROUND AND OBJECTIVES A major cause of skin aging is a chronic microinflammation created by environmental conditions and ultraviolet exposures. The hand-free application on the skin of a new intense light combining a narrowband blue-light (405- to 420-nm) antiinflammatory emission and a near-infrared (850- to 890-nm) emission inducing self-defense mechanisms provides a new component to photorejuvenation and antiaging treatment protocols.STUDY DESIGN An innovative skin rejuvenation schedule is presented in this study. It includes skin exposure to the light, with concomitant glycolic peels and daily vitamin C cream regimen for group A and only topical vitamin C cream and glycolic peels for control group B.RESULTS Results show a significant improvement on pore size, rhytids, and radiance in group A. Conversely no improvement is noticed in group B except for a brief increase of skin radiance. Mechanisms of action of that specific light source are discussed.CONCLUSION The exposure to this device can clinically enhance conventional antiaging protocols in skin rejuvenation.

The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment.

Key Words exobiology, astrobiology, bioastronomy, optical SETI, life in the universe s Abstract The search for evidence of extraterrestrial intelligence is placed in the broader astronomical context of the search for extrasolar planets and biomarkers of primitive life elsewhere in the universe. A decision tree of possible search strategies is presented as well as a brief history of the search for extraterrestrial intelligence (SETI) projects since 1960. The characteristics of 14 SETI projects currently operating on telescopes are discussed and compared using one of many possible figures of merit. Plans for SETI searches in the immediate and more distant future are outlined. Plans for success, the significance of null results, and some opinions on deliberate transmission of signals (as well as listening) are also included. SETI results to date are negative, but in reality, not much searching has yet been done.

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188) Washington DC 20503.

Laboratory dryer was designed in such a way that drying could be done either with infrared energy or by convection. It was equipped with near-infrared radiators with peak wavelength at 1200 nm. The energy efficiency of the infrared dryer was between 35% and 45%. Apple slices were dried with infrared energy and by convection under equivalent conditions. Kinetics of infrared drying was dependent on the distance between emitters and the heat-irradiated surface and air velocity. Drying kinetics was inversely proportional to both the distance and the air velocity. It was found that both surfaces of apple slice participate in water evaporation. However, the heat-irradiated surface evaporates much more water than that not heated by infrared energy until 80% of water is removed from the material. At the final stages of drying, there is no difference between upper and bottom surfaces of the apple slice as far as the flux of evaporated water is concerned.

The main sources of non-luminous gas radiation in furnaces are carbon dioxide and water vapor. Approximation of the standard emissivities of water vapor and of carbon dioxide by mixed gray-gas model is studied. The model developed for carbon dioxide standard emi s si vi ti es covers a range of temperature of 3DO-1BOOK and a partial-pressure-length product range of 0.01 to 10 m atm. A mixture of six gray gases was adequate to cover the whole range. For the water vapor thermal radiation two models were developed to approximate the standard water~apor emissi~ities. In the first model water~apor is approximated by a mixture of four gray-gases and can be used in the temperature range of 300-700K and the partial-pressure-length range of 0.01 to 2 m atm. The second model is a piece-wise one in which one gray gas is used to cover the pL range 0.5-2 m and a second gray gas covered the range of 0.05-0.5 m. The model may be used in the temperature range of 700-l500K and has an error range of-2.3 to 3.7~. 1.

The sintering kinetics and microstructural evolution of alumina tubes (∼17 mm length, ∼9 mm inner diameter, and ∼11 mm outer diameter) were studied by conventional and microwave heating at 2.45 GHz. Temperature during microwave heating was measured with an infrared pyrometer and was calibrated to ±10°C. With no hold at sintering temperature, microwave-sintered samples reached 95% density at 1350°C versus 1600°C for conventionally heated samples. The activation energy for microwave sintering was 85 ± 10 kJ/mol, whereas the activation energy for conventionally sintered samples was 520 ± 14 kJ/mol. Despite the difference in temperature, grains grew from ∼1.0 μm at 86% density to ∼2.6 μm at 98% density for both conventionally sintered and microwave-sintered samples. The grain size/density trajectory was independent of the heating source. It is concluded that the enhanced densification with microwave heating is not a consequence of fast-firing and therefore is not a result in the change in the relative rates of surface and grain boundary diffusion in the presence of microwave energy.

This article aims to review and analyze the aspects and characteristics related to infrared food drying. Indeed, with a review of 100 relevant publications all dealing with infrared food drying, this article notes that infrared drying has several advantages over other common food drying methods. Shorter drying time, a better final dried product quality, and more energy savings in the process are revealed as the most important advantages of infrared drying over convective heat drying. Infrared dryers can also be easily combined with other drying methods such as hot air, microwave, vibration, and vacuum. This article clearly shows that using infrared heating for food drying purposes has become more popular in the last decade and its application in the industrial drying of different foodstuffs has been employed widely.

A laboratory scale infrared-convective dryer was developed and single layer drying of onion slices was carried out at infrared power levels of 300, 400 and 500 W, drying air temperatures of 35, 40 and 45 °C and inlet drying air velocities of 1.0, 1.25 and 1.5 m/s. The drying time reduced by about 2.25 times on increasing infrared power from 300 to 500 W, air temperature 35–45 °C and air velocity from 1.0 to 1.5 m/s. Effective moisture diffusivity varied from 0.21 × 10−10 to 1.57 × 10−10 m2/s and was significantly influenced by infrared power and air temperature.. The rehydration ratio of dehydrated onion slices was found to be in the range of 4.5 and 5.3.

Using a triple-layer antireflection coating of Al 2 O 3 , Si, and SiO 2 , we have achieved a minimum facet reflectivity of 1 3 10 26 and a bandwidth of 90 nm for a reflectivity of 5 3 10 25 or less for 1550-nm center-wavelength InGaAsP semiconductor lasers. A facet reflectivity of 3 3 10 26 and a bandwidth of 30 nm for a reflectivity of 5 3 10 25 were achieved for 1310-nm InGaAsP lasers. This coating is applicable to broadband external-cavity-tuned laser sources, edge-emitting light-emitting diodes, and semiconductor laser amplifiers.

The effects of the ambient atmosphere in the annealing chamber on the electrical and structural characteristics of Zn-implanted III-V compound semiconductors, processed by low-power pulsed-laser annealing are presented. The samples were analyzed using several complementary experimental techniques: Reflection highenergy electron diffraction, Rutherford backscattering spectroscopy, Raman spectroscopy, secondary ion mass spectroscopy, and electrical measurements. During the laser beam irradiation in the presence of gas inlet into the annealing chamber the ambient gas atoms diffused well into the target changing the stoichiometry and the electrical parameters. Redistribution of the implanted impurity was also observed. By varying the type of gas used and its pressure, it was possible to achieve electrical activation of up to 80%. It seems all structure and electrical parameters achieve their best values at the same ambient atmosphere and density of the deposited laser power P, e.g., 1.5 atm of N 2 and Pϭ6.5 MW/cm 2 for InP.

We demonstrated that modulated infrared radiation can cause the resonant excitation of plasma oscillations in quantum well diode and transistor structures with high electron mobility. This effect provides a new mechanism for the generation of tunable terahertz radiation using photomixing of infrared signals. We developed a device model for a quantum well photomixer and calculated its high-frequency performance. It was shown that the proposed device can significantly surpass photomixers utilizing standard quantum well infrared photodetectors.

We retrospectively analyzed the temporal and spatial variations of four different physical parameters characterizing the state of the atmosphere and ionosphere several days before the M 9 Tohoku, Japan earthquake of March 11, 2011. The data include outgoing long wave radiation (OLR), GPS/TEC, lower Earth orbit ionospheric tomography and critical frequency foF2. Our first results show that on March 7th a rapid increase of emitted infrared radiation was observed from the satellite data and an anomaly developed near the epicenter. The GPS/TEC data indicate an increase and variation in electron density reaching a maximum value on March 8. Starting from this day in the lower ionosphere also there was confirmed an abnormal TEC variation over the epicenter. From March 3 to 11 a large increase in electron concentration was recorded at all four Japanese ground-based ionosondes, which returned to normal after the main earthquake. The jointly preliminary analysis of atmospheric and ionospheric parameters during the M 9 Tohoku, Japan earthquake has revealed the presence of related variations of these parameters implying their connection with the earthquake process. This study may lead to a better understanding of the response of the atmosphere/ionosphere to the great Tohoku earthquake.

В работе теоретически исследуется модификация метода испарительной литографии, когда в систему добавлен ИК-излучатель. Полимерные покрытия с периодической структурой, повторяющей шаблон с точностью до миллиметрового размера, формируются поперечными потоками в жидких растворах коллоидных частиц. Течение возникает из-за неравномерного испарения с поверхности жидкой пленки в результате ИК-нагрева через теневую маску. Разрабатывается математическая модель, которая описывает динамику коллоидной жидкости, эволюцию массовой доли латексных частиц в водном растворе, перенос тепла в жидком слое и твердом основании. Результаты численных расчетов предсказывают, что перепад температуры в коллоидной пленке может составлять несколько градусов. Динамика температуры жидкости значительно зависит от теплоотдачи подложкой при малых значениях числа Гретца. Показано, что ИК-излучение, проходящее через отверстие в маске, нагревает не только тонкий жидкий слой, но и твердое основание под ним.

The aim of this work is to minimize the drying time of a polymer aqueous solution placed into a Petri dish while respecting strict constraints. Several experiments performed in a laboratory setup have shown the interest of a drying combining convective and infrared radiation as long as irradiation is correctly controlled. In this way, a one dimensional liquid diffusion model taking into account the product shrinkage was developed. Model predictions are in good adequacy to mass and temperature experimental data.