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A new comparative interferometric method has been developed to measure the thermal conductivity of nanofluids. The thermal conductivity of Al 2 O 3 -water nanofluid is measured relative to deionized water by comparing the steady-state temperature field in the two fluids separated by a conductive barrier using a Mach-Zehnder Interferometer. The method is not restricted to nanofluids and could potentially be used to measure the thermal conductivity of any transparent fluid. Moreover, the method is almost independent of the thermocouple temperature measurement accuracy, with optical errors in the fringe gradients being the primary source of measurement uncertainty. The uncertainty in the relative thermal conductivity measurements is estimated to be ± 6 %. For comparison, the thermal conductivity obtained by this technique is compared to transient hot wire measurements. The reliability of the comparative method is also demonstrated by measuring the thermal conductivity of deionized water. Subsequently, the relative thermal conductivities of Al 2 O 3 -water nanofluids with the concentration of 0.02, 0.05, 0.08, and 0.11 wt% are attained by the two methods at room temperature. This range of concentrations is of interest because anomalously high thermal conductivity has been reported in previous interferometric studies. The results indicate that the thermal conductivity obtained from the comparative interferometric method agrees with the transient hot wire results to better than 2.3 %. Moreover, the thermal conductivity of water-based Al 2 O 3 nanofluids with a weight concentration of less than 0.11 % is the same as deionized water within the uncertainty of the measurement methods. [ABSTRACT FROM AUTHOR]

Individual variation of the hypothalamic-pituitary-adrenal (HPA) axis response to stress could contribute to variable stress resiliency of livestock. During stress events, the innate immune system can also become activated and work in concert with the neuroendocrine system to restore homeostasis, while minimizing tissue damage. The purpose of this study was to assess immune function in variable stress-responding sheep in response to bacterial lipopolysaccharide (LPS) endotoxin immune-challenge. High (HSR, n = 12), middle (MSR, n = 12), and low-stress responders (LSR, n = 12) were selected from a population of 112 female lambs and classified based on serum cortisol concentration after receiving an intravenous bolus of LPS (400 ng/kg). Blood was collected from the jugular vein at 0 and 4 hrs post-LPS challenge to monitor changes in serum pro- and anti-inflammatory cytokines and chemokines, and white blood cell populations. Rectal temperature was recorded hourly to monitor fever. HSR had the greatest increase in rectal temperature and strongest pro-inflammatory IL-6 and IFN-γ cytokine responses compared to MSR and LSR. HSR and MSR had stronger anti-inflammatory IL-10 cytokine and CCL2 chemokine responses than LSR. White blood cell counts changed between 0 and 4 h; however, no differences were detected among the variable stress response groups. The distinct inflammatory response in variable stress responding sheep could contribute to individual differences in stress resiliency and this warrants investigation in the context of other types of stress. Acute inflammation was studied in sheep stress-phenotyped using bacterial lipopolysaccharide. Sheep selected based on stress responsiveness (i.e. serum cortisol concentration) have different immune responses to bacterial stress. Specifically, high-stress responders have a more pronounced inflammatory response than low-stress responders. [ABSTRACT FROM AUTHOR]

Breeding stress-resilient livestock is a potential strategy to help mitigate the negative effect of environmental and pathogenic stressors. The hypothalamic-pituitary-adrenal axis and immune system are activated during stress events and release mediators into the circulation that help restore physiological homeostasis. The purpose of this study was to assess a comprehensive set of circulatory mediators released in response to an acute immune stress challenge to identify candidate biomarkers that can be used for the selection of stress-resilient animals. Fifteen female lambs were stress challenged with an intravenous bolus of lipopolysaccharide (LPS; 400 ng/kg), and blood was collected from the jugular vein at 0, 2, 4, and 6 h after LPS challenge to identify and monitor candidate stress biomarkers; temperature was also recorded over time. Biomarker responses were evaluated with a repeated-measures model to compare time points with baseline values. As expected, all sheep had a monophasic febrile response to LPS challenge, and cortisol increased and returned to baseline by 6 h. The cytokines tumor necrosis factor-α, IL-6, IFN-γ (proinflammatory), and IL-10 (anti-inflammatory) increased, but only tumor necrosis factor-α returned to baseline during the monitoring period. The cytokines IL-1α, IL-1β, IL-17α (proinflammatory), and IL-4 (anti-inflammatory) did not respond to LPS challenge. All chemokines (CCL2, CCL3, CCL4, CXCL10, and IL-8) responded to LPS challenge; however, only CCL2, CCL3, CCL4, and CXCL10 increased over time, and only CCL3, CCL4, and CXCL10 returned to baseline during the monitoring period. MicroRNA (miR-145, miR-233, and miR-1246) also increased and remained elevated during the study. In summary, the LPS challenge induced a strong stress response in Rideau-Dorset sheep that could be monitored with a distinct profile of circulatory biomarkers. [ABSTRACT FROM AUTHOR]

Reports on the fidelity of optical phase conjugation by photorefractive degenerate four-wave mixing in barium titanate. Effects of angular misalignment of the incident laser beams; Analysis of photorefractive four-wave mixing based upon volume holography; Diffraction efficiency of a photorefractive grating.

A numerical study is conducted of laminar free convection from a vertical window glazing adjacent to an insect screen which is modeled as a layer of porous medium. The numerical results are validated against optical temperature field visualization and local heat flux measurements. The numerical model is also shown to agree well with established correlations for the heat transfer at the upper and lower asymptotic limits of screen permeability. Results are presented for Rayleigh number (based on the glazing height) of Ra H = 10 6 –10 9 , and for window height to screen spacing ratios of H/W = 25, 60 and 100. Under some conditions, the flow resistance of the insect screen is found to reduce the convective heat transfer rate from the glazing by more than 50%. Generally, it was found that the screen has less effect on the convective heat transfer rate as the Rayleigh number increases. Also, in the range of parameters corresponding to most practical window applications, decreasing the screen to window spacing reduces the convective heat transfer rate from the glazing. A general correlation for use in window analysis is presented that accounts for the effect of an insect screen on the average convection coefficient at the glazing. [ABSTRACT FROM AUTHOR]

Dust grains play a key role in the physics of star-forming regions, even though they constitute only ~1 per cent of the mass of the interstellar medium. The derivation of accurate dust parameters such as temperature (Td), emissivity spectral index (β) and column density requires broad-band continuum observations at far-infraredwavelengths.We present Herschel-Spectral and Photometric Imaging Receiver Array (SPIRE) Fourier Transform Spectrometer (FTS) measurements of three starless cores: L1521E, L1521F and L1689B, covering wavelengths between 194 and 671 μm. This paper is the first to use our recently updated SPIRE-FTS intensity calibration, yielding a direct match with SPIRE photometer measurements of extended sources. In addition, we carefully assess the validity of calibration schemes depending on-source extent and on the strength of background emission. The broad-band far-infrared spectra for all three sources peak near 250 μm. Our observations therefore provide much tighter constraints on the spectral energy distribution (SED) shape than measurements that do not probe the SED peak. The spectra are fitted using modified blackbody functions, allowing both Td and β to vary as free parameters. This yields Td of 9.8±0.2, 15.6±0.5 and 10.9±0.2 K and corresponding β of 2.6∓0.9, 0.8∓0.1 and 2.4∓0.8 for L1521E, L1521F and L1689B, respectively. The derived core masses are 1.0±0.1, 0.10±0.01 and 0.49±0.05M☉, respectively. The core mass/Jeans mass ratios for L1521E and L1689B exceed unity indicating that they are unstable to gravitational collapse, and thus pre-stellar cores. By comparison, the elevated temperature and gravitational stability of L1521F support previous arguments that this source is more evolved and likely a protostar. [ABSTRACT FROM AUTHOR]

We present the data processing pipeline to generate calibrated data products from the Spectral and Photometric Imaging Receiver (SPIRE) imaging Fourier Transform Spectrometer on the Herschel Space Observatory. The pipeline processes telemetry from SPIRE observations and produces calibrated spectra for all resolution modes. The spectrometer pipeline shares some elements with the SPIRE photometer pipeline, including the conversion of telemetry packets into data timelines and calculation of bolometer voltages. We present the following fundamental processing steps unique to the spectrometer: temporal and spatial interpolation of the scan mechanism and detector data to create interferograms; Fourier transformation; apodization; and creation of a data cube. We also describe the corrections for various instrumental effects including first- and second-level glitch identification and removal, correction of the effects due to emission from the Herschel telescope and from within the spectrometer instrument, interferogram baseline correction, temporal and spatial phase correction, non-linear response of the bolometers, and variation of instrument performance across the focal plane arrays. Astronomical calibration is based on combinations of observations of standard astronomical sources and regions of space known to contain minimal emission. [ABSTRACT FROM AUTHOR]

Molecular gas constitutes the dominant mass component of protoplanetary discs. To date, these sources have not been studied comprehensively at the longest far-infrared and shortest submillimetre wavelengths. This paper presents Herschel SPIRE FTS spectroscopic observations towards 18 protoplanetary discs, covering the entire 450–1540 GHz (666–195 μm) range at ν/Δν ≈ 400–1300. The spectra reveal clear detections of the dust continuum and, in six targets, a significant amount of spectral line emission primarily attributable to 12CO rotational lines. Other targets exhibit little to no detectable spectral lines. Low signal-to-noise detections also include signatures from 13CO, [C i] and HCN. For completeness, we present upper limits of non-detected lines in all targets, including low-energy transitions of H2O and CH+ molecules. The 10 12CO lines that fall within the SPIRE FTS bands trace energy levels of ∼50–500 K. Combined with lower and higher energy lines from the literature, we compare the CO rotational line energy distribution with detailed physical–chemical models, for sources where these are available and published. Our 13CO line detections in the disc around Herbig Be star HD 100546 exceed, by factors of ∼10–30, the values predicted by a model that matches a wealth of other observational constraints, including the SPIRE 12CO ladder. To explain the observed 12CO/13CO ratio, it may be necessary to consider the combined effects of optical depth and isotope selective (photo)chemical processes. Considering the full sample of 18 objects, we find that the strongest line emission is observed in discs around Herbig Ae/Be stars, although not all show line emission. In addition, two of the six T Tauri objects exhibit detectable 12CO lines in the SPIRE range. [ABSTRACT FROM AUTHOR]

Laser interferometry and flow visualization were used to study free convective heat transfer inside a vertical channel. Most studies in the literature have investigated buoyancy forces in a single direction. The study presented here investigated opposing buoyancy forces, where one wall is warmer than the ambient and the other wall is cooler than the ambient. An experimental model of an isothermally, asymmetrically heated vertical channel was constructed. Intetferometry provided temperature field visualization and flow visualization was used to obtain the streamlines. Experiments were carried out over a range of aspect ratios berween 8.8 and 26.4, using temperature ratios of 0, --0.5, and --0.75. These conditions provide a modified Rayleigh number range of approximately 5 to 1100. In addition, the measured local and average Nusselt number data were compared to numerical solutions obtained using ANSYS FLUENT. Air was the fluid of interest. So the Prandtl number was fixed at 0.71. Numerical solutions were obtained for modified Rayleigh numbers ranging from the laminar fully developed flow regime to the turbulent isolated boundary layer regime. A semi-empirical correlation of the average Nusselt number was developed based on the experimental data. [ABSTRACT FROM AUTHOR]

Highlights: [•] Free convection in a vertical channel with opposing buoyancy forces is studied. [•] Flow visualization is used to obtain the streamlines/streaklines. [•] Laser interferometry is used to obtain the temperature-field. [•] The opposing buoyancy forces produce instability inside the channel. [Copyright &y& Elsevier]

Free convection in a vertical channel with antisymmetrical heating is a special case that has not received a great deal of attention in the literature. Antisymmetrical heating is where the hot wall is heated above the ambient temperature by the same amount that the cold wall is cooled below the ambient, giving equal but opposing buoyancy forces inside the channel. An experimental model was constructed to study antisymmetrical heating inside an isothermally heated vertical channel. Flow visualization was used to obtain the flow field and laser interferometry was used to obtain the temperature field. Based on the measured temperature field, the local and average Nusselt numbers were determined, which were compared with numerical predictions obtained using ANSYS FLUENT. A range of Rayleigh numbers were studied for air with a Prandtl number of 0.71. The results show that an open-ended channel with antisymmetrical heating has some similarities to a tall enclosure. The average convective heat transfer can be approximated using an existing correlation for a tall enclosure from the literature. [ABSTRACT FROM AUTHOR]

The paper presents results from a range of petroleum exploration studies carried out in Jordan - some regional in approach, others focussed on the NE of the country - together with a review of existing literature and industry reports. The dominant active structural feature in Jordan is the NNW-SSE striking Dead Sea Transform, characterised in southern Jordan by extensional splay fault arrays, pull-apart basins and relay-sag basins. Elsewhere in the country there are regional-scale strike-slip faults (ENE-WSW, NNW-SSE) with multiple phases of reactivation. Stratigraphic studies have identified potential reservoir intervals within the Lower Palaeozoic Salib, Umm Sahm, Disi and upper Dubaydib (Risha Sandstone Member) Formations, and also within the Triassic and Cretaceous intervals. Potential source rocks occur within the Lower Palaeozoic Burj, lower Hiswa and Dubaydib Formations and at basal and Upper Silurian levels, with limited additional potential in the Triassic and possibly Permian successions. Apatite fission track analysis (AFTA), zircon fission track analysis (ZFTA) and vitrinite reflectance (VR) studies of selected wells and outcrop samples indicate that the thermal history of eastern Jordan is dominated by the effects of two major periods of relatively deep burial, with subsequent exhumation phases beginning in the Late Palaeozoic and Late Cenozoic. An intermediate episode (Mesozoic) of deep burial and exhumation is possible. Significant variations in heat flow regimes and burial patterns occur in different parts of Jordan, probably controlled by deep structure and burial history. Over much of the north of the country, the Lower Palaeozoic succession is in the gas window and the underlying section is overmature. The main hydrocarbon generation and expulsion phase in this region was in the Late Palaeozoic and was terminated by 'Hercynian' (Late Palaeozoic) uplift. Further south, the Silurian and Upper Ordovician sections are in the oil window, and deeper source intervals are mature for gas. The Triassic interval is a valid hydrocarbon play in the NW and NE of Jordan, with oil sourced from either Permian, Triassic or Cretaceous kitchens. Upper Cretaceous source rocks within the thicker Mesozoic sections in the Azraq Graben are in the oil window and have sourced the small-scale Hamza oilfield. In addition to the known widespread Upper Cretaceous - Paleocene oil shale potential in Jordan, the Ordovician and Silurian sections have potential for shale gas in northern Jordan and for shale oil further south. [ABSTRACT FROM AUTHOR]

Abstract: An experimental study has been conducted to examine free convection in a window with an enclosed aluminum venetian-type blind. The unique feature of this experiment was that the blind slats were heated electrically to simulate absorbed solar radiation. Convective heat transfer measurements and temperature field visualization were obtained using a Mach–Zehnder laser interferometer. Optical measurements were made for two glazing spacings, two blind slat angles, two blind heat flux levels, and two glazing temperature differences. Both local and average convective heat flux data were obtained in the center region of the tall air-filled enclosure. At the widest glazing spacing, the temperature field was found to be unsteady. For these cases, the temporal fluctuation of the local convective heat transfer was time-averaged using a high speed camera. The experimental results have been compared to a simplified method in the literature for predicting the center-glass heat flux for this configuration. [Copyright &y& Elsevier]

Abstract: When convective heat transfer measurements are made using a laser interferometer, optical windows are often used to separate the test fluid inside the experimental model from the ambient air. In the present study, the measurement error caused by the thermal boundary layers that form on the exterior surfaces of the optical windows has been analyzed. A convenient analytical expression for the error in the fringe gradient has been derived, using the two-dimensional similarity solution for laminar free convective flow. For typical experimental conditions this source of bias error was found to be generally small, except near the leading edge of the thermal boundary layer. Based on the results, it is recommended that the measurement region be at least five centimeters away from the leading edge of these external thermal boundary layers. [Copyright &y& Elsevier]

Abstract: A numerical study has been conducted of steady free convection in a double glazed window with a between-panes pleated cloth blind. The model geometry is based on a commercial product that is available on the consumer market in North America. The study considers the effects of Rayleigh number, enclosure aspect ratio, and blind geometry on the convective heat transfer. A simplified model of the coupled convective and radiative heat transfer is also presented. Sample results show that the average Nusselt number data from the CFD study can be combined with a one-dimensional model to closely predict the glazing-to-glazing U-value. [Copyright &y& Elsevier]

Abstract: A numerical study has been conducted of free convection in a tall vertical enclosure with an internal louvered metal blind. The study considers the effects of Rayleigh number, enclosure aspect ratio, and blind geometry on the convective heat transfer. The numerical model has been validated against experimental measurements and the results have been presented in terms of an empirical correlation for the average Nusselt number. The correlation is applicable to an enclosure with an internal metal blind. It has been shown that the Nusselt number correlation can be combined with a simple one-dimensional model to closely predict the enclosure U-value. [Copyright &y& Elsevier]

Status epilepticus (SE) describes an enduring epileptic state during which seizures are unremitting and tend to be self-perpetuating. We describe the clinical phases of generalized convulsive SE, impending SE, established SE, and subtle SE. We discuss the physiological and biochemical cascades which characterize self-sustaining SE (SSSE) in animal models. At the transition from single seizures to SSSE, GABAA (gamma-aminobutyric acid) receptors move from the synaptic membrane to the cytoplasm, where they are functionally inactive. This reduces the number of GABAA receptors available for binding GABA or GABAergic drugs, and may in part explain the development of time-dependent pharmacoresistance to benzodiazepines and the tendency of seizures to become self-sustaining. At the same time, ‘spare’ subunits of AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and NMDA (N-methyl-D-aspartic acid) receptors move from subsynaptic sites to the synaptic membrane, causing further hyperexcitability and possibly explaining the preserved sensitivity to NMDA blockers late in the course of SE. Maladaptive changes in neuropeptide expression occur on a slower time course, with depletion of the inhibitory peptides dynorphin, galanin, somatostatin and neuropeptide Y, and with an increased expression of the proconvulsant tachykinins, substance P and neurokinin B. Finally, SE-induced neuronal injury and epileptogenesis are briefly discussed. [ABSTRACT FROM AUTHOR]

An experimental study has been conducted on natural convective heat transfer in an idealized double-glazed window with a between-panes louvered blind. A Mach-Zehnder interferometer has been used to obtain full-field temperature visualization, as well as local and average convective heat transfer rates. A blind, consisting of 17 horizontal aluminium slats, was mounted inside a tall vertical enclosure formed by two aluminium plates and two acrylic end spacers. Temperature field visualization and measurements were obtained for three plate spacings and three blind slat angles over a Rayleigh number range (based on the enclosure width) of 4.6 × 104 ≤ Ra ≤ 1.3 × 105. Air was the fill gas. The results show that the inter-pane blind has a strong influence on the local and average convective heat transfer rates. In general, a between-panes blind was found to reduce the average convective heat transfer rate across the window, relative to an empty enclosure. At the three plate spacings studied, a closed blind was found to yield the lowest average convective heat transfer rates. [ABSTRACT FROM AUTHOR]

An approximate method is presented for predicting the effect of a louvered blind on the centre-glass thermal performance of a fenestration. The method combines a one-dimensional heat transfer model with data from a numerical simulation of the window and blind. Sample results for a blind mounted on the indoor surface of a window show the effect of blind slat angle on heat transmission. Both summer and winter conditions are considered. The results show that a louvered blind can improve the U-value of a standard double-glazed window by up to 37%. Also, the radiation heat exchange with the room can be dramatically reduced (by up to 60%), which will improve the level of occupant comfort. However, there was found to be a trade-off between U-value and occupant comfort; placing the blind closer to the window improves the U-value, but increases the radiation heat exchange with the room. The predictions from the present simplified method compare well with results from a full two-dimensional computational fluid dynamics solution of the conjugate blind/window interaction. [ABSTRACT FROM AUTHOR]

A numerical model has been developed of the conjugate convection, conduction, and radiation heat transfer in a double-glazed window with a between-panes venetian-type blind. The two-dimensional finite-volume model has been validated for a range of slat angles using U value measurements from the literature. Data from this solution have been used to show that the thermal performance of the window/blind enclosure can be closely approximated using a simplified model. Such simplified methods of analysis are of utility in fenestration design software. [ABSTRACT FROM AUTHOR]

An asymptotic expansion valid for large positive values of s is constructed for the integral transform F(s) = &integ;0&infinf(x)Kis(x) dx/x where Kis(x) denotes the modified Bessel function of purely imaginary order s and the function f(x) is analytic in a suitable sector containing the positive real axis and possesses the asymptotic expansion f(x)∼ex cos γ ∑n=0∞ anx1-n-c as x → ∞ in this sector, where γ is complex; 0 < c < 1 and 0 ≤ Re(cos γ,) < 1. [ABSTRACT FROM AUTHOR]

In this paper, a brief introduction is given to the principle of operation of both classical and holographic interferometers, which are commonly used for the measurement of convective heat transfer rates. Some of the optical considerations, as well as the limitations of this experimental technique are highlighted. With this background, some recent developments in laser interferometry are discussed for both two- and three-dimensional temperature fields, with an emphasis on techniques for measuring local convective heat flux rates. [Copyright &y& Elsevier]

Examines the accuracy of beam-averaged interferometric heat transfer rate measurements made in ideal gases. Problem definition; Methods used in the study; Analysis of beam-averaged heat transfer rates.

An asymptotic expansion valid for large positive values of s is constructed for the integral transformF(s)=∫lower limit 0, upper limit ∞ Kis(x)f(x)dx/x,where Kis(x) denotes the modified Bessel function of the third kind of purely imaginary order. The expansion applies to functions f(x) that are analytic in the sector |arg(x)|&les;π/4 and that are exponentially damped and oscillatory as x→∞ in this sector. [Copyright &y& Elsevier]

A classical or holographic interferometer can be used to measure the average fluid temperature integrated in the direction of the test/object beam. However, such beam-averaged measurements are not exact for a three-dimensional temperature field, when a standard two-dimensional analysis technique is applied. In the current study, an analysis is performed to determine the error in the average fluid temperature measurement caused by temperature variations in the light beam direction. The error has been calculated for both an ideal gas and water as the test fluid. The results show that for typical experimental conditions, the measurement error introduced by this temperature variation is less than 2%, even for the most adverse temperature distribution in the light beam direction. For reasons discussed in this article, this result may promote the wider application of interferometry to three-dimensional heat transfer problems. [ABSTRACT FROM AUTHOR]

An interferogram analysis technique for the measurement of convective heat transfer rates is described in which the local surface temperature gradient is measured directly from a wedge fringe field. It is shown that the local surface gradient for a two-dimensional temperature field can be obtained directly by measuring the angle of intersection of a wedge fringe with an isothermal surface. An uncertainty analysis is performed and it is shown that this "direct gradient method" is best suited for the measurement of relatively low temperature gradients. An expression for the optimum wedge fringe spacing and a correction term for refraction effects are also derived. Measurements of the free convective heat transfer from an isothermal vertical flat plate are made and compared to the exact boundary-layer solution. [ABSTRACT FROM AUTHOR]

Presents the design and performance of a dual polarizing bolometer detector system for use with a polarizing Fourier transform spectrometer to conduct broadband astronomical spectroscopy at submillimeter wavelengths. Inclusion of a fully differential electronics design which eliminates common mode noise; Minimization of the effects of resonant optical cavities.

Examines how the African Methodist Episcopal (AME) Church transformed the World's Parliament of Religions, a part of the Chicago World's Fair in 1893, into a world court of opinion regarding racial equity. Black's rhetoric of equity; Characteristics of AME church; Construction and extension of the rhetorics.

Laser interferometry is combined with high-speed digital cinematography to measure time-averaged transient and turbulent convective heat transfer rates. The method is applied to study free convection in a tall vertical air-filled enclosure. Measurements are made at three wall spacings in the turbulent flow regime (5.2×104 ⩽ Raw ⩽ 2.8×105). An automated image processing algorithm is used to calculate the instantaneous local heat flux from a sequence of interferograms that is captured by a high-speed camera. The local Nusselt number distributions on the hot and cold walls are obtained by time-averaging the fluctuations in local heat flux. The effects of key experimental parameters, such as the camera frame rate and the total image capture time, are investigated. For the current problem, it is shown that a total capture interval of about 10 s is required to accurately measure the time-average local Nusselt number. Within the measurement uncertainty, the average Nusselt number results are in agreement with a widely used empirical correlation from the literature. [ABSTRACT FROM AUTHOR]

Presents flow and temperature field visualization photographs obtained as part of a project that examined the effect of shading devices on the thermal performance of windows. Sketch of the experimental geometry; Flow visualization showing the effect of solar heat flux on the flow between the slats; Comparison of infinite fringe interferograms with numerical isotherms for blind slat angles.

This paper reports the visualization of the temperature field in light-transmitting nanofluids using a Mach–Zehnder interferometer. In this study, the evolution of the free convective temperature fields around a resistively heated vertical metal strip was observed in two nanofluids. Visualization has been obtained using a 15 mW He-Ne laser (632.8 nm) for SiO 2 –water and Al 2 O 3 –water nanofluids over a range of concentrations. The optical path length of the test beam through the nanofluid was 7 mm. The results show that a SiO 2 –water nanofluid can be used up to a concentration of at least 40% by weight. Al 2 O 3 –water nanofluid can be used up to at least 1% concentration by weight, provided the solution is adequately homogenized. This work demonstrates that optical temperature field and the local heat flux measurements are technically feasible in these nanofluids. [ABSTRACT FROM AUTHOR]

We have used a Fourier Transform Spectrometer (FTS) on the James Clerk Maxwell Telescope (JCMT) to study the submillimetre continuum emission from dust in three hot molecular cores (HMCs). The spectral index β of the dust emission for these sources has been determined solely within the 30-GHz wide 350-GHz (850 μm) passband to an accuracy comparable to those determined through multiwavelength observations. We find an average , in agreement with spectral indices determined from previous submillimetre observations of these sources and with those determined for HMC in general. The largest single source of uncertainty in these results is the variability of the atmosphere at 350 GHz, and with better sky subtraction techniques we show that the dust spectral index can clearly be determined within one passband to high accuracy with a submillimetre FTS. Using an imaging FTS on the Submillimetre Common User Bolometer Array (SCUBA)-2, the next generation wide-field submillimetre camera currently under development to replace SCUBA at the JCMT in 2006, we calculate that at 350 GHz it will be possible to determine β to ±0.1 for sources as faint as 400 mJy beam−1 and to ±0.3 for sources as faint as 140 mJy beam−1. [ABSTRACT FROM AUTHOR]

Examines the influence of heated, horizontal and rotatable louvers on the convective heat transfer from a heated or cooled vertical isothermal surface. Determination of the temperature field and local surface flux data; Comparison of results with that from a conduction/convection/radiation finite element model; Effect of the heated louvers on the heat transfer rate from the plate surface.

Examines the influence of heated, horizontal and rotatable louvers on the convective and radiative heat transfer from a heated or cooled vertical isothermal surface. Description of the physical model used in the study; Governing equations; Discussion of results.

We provide a detailed description of the Herschel /SPIRE Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF). The FF is an automated process designed to extract significant spectral features from SPIRE FTS data products. Optimizing the number of features found in SPIRE-FTS spectra is challenging. The wide SPIRE-FTS frequency range (447–1568 GHz) leads to many molecular species and atomic fine structure lines falling within the observed bands. As the best spectral resolution of the SPIRE-FTS is ∼1.2 GHz, there can be significant line blending, depending on the source type. In order to find, both efficiently and reliably, features in spectra associated with a wide range of sources, the FF iteratively searches for peaks over a number of signal-to-noise ratio (SNR) thresholds. For each threshold, newly identified features are rigorously checked before being added to the fitting model. At the end of each iteration, the FF simultaneously fits the continuum and features found, with the resulting residual spectrum used in the next iteration. The final FF products report the frequency of the features found and the associated SNRs. Line flux determination is not included as part of the FF products, as extracting reliable line flux from SPIRE-FTS data is a complex process that requires careful evaluation and analysis of the spectra on a case-by-case basis. The FF results are 100 per cent complete for features with SNR greater than 10 and 50–70 per cent complete at SNR of 5. The FF code and all FF products are publicly available via the Herschel Science Archive. [ABSTRACT FROM AUTHOR]

The European Space Agency Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. We present the extension of the FF to include the off-axis detectors of the FTS in sparsely sampled single-pointing observations, the results of which have been ingested into the catalogue. We also present the results from an automated routine for identifications of the atomic/molecular transitions that correspond to the spectral features extracted by the FF. We use a template of 307 atomic fine structure and molecular lines that are commonly found in SPIRE FTS spectra for the cross-match. The routine makes use of information provided by the line identification to search for low signal-to-noise ratio features that have been excluded or missed by the iterative FF. In total, the atomic/molecular transitions of 178 942 lines are identified (corresponding to 83 per cent of the entire FF catalogue), and an additional 33 840 spectral lines associated with missing features from SPIRE FTS observations are added to the FF catalogue. [ABSTRACT FROM AUTHOR]

The most intensively star-forming galaxies are extremely luminous at far-infrared (FIR) wavelengths, highly obscured at optical and ultraviolet wavelengths, and lie at |$z$| ≥ 1–3. We present a programme of FIR spectroscopic observations with the SPIRE FTS, as well as photometric observations with PACS, both on board Herschel, towards a sample of 45 gravitationally lensed, dusty starbursts across |$z$| ∼ 1–3.6. In total, we detected 27 individual lines down to |$3\, \sigma$|⁠, including nine [C  ii ] 158  |$\mu$| m lines with confirmed spectroscopic redshifts, five possible [C  ii ] lines consistent with their FIR photometric redshifts, and in some individual sources a few [O  iii ] 88  |$\mu$| m, [O  iii ] 52  |$\mu$| m, [O  i ] 145  |$\mu$| m, [O  i ] 63  |$\mu$| m, [N  ii ] 122  |$\mu$| m and OH 119  |$\mu$| m (in absorption) lines. To derive the typical physical properties of the gas in the sample, we stack all spectra weighted by their intrinsic luminosity and by their 500 |$\mu$| m flux densities, with the spectra scaled to a common redshift. In the stacked spectra, we detect emission lines of [C  ii ] 158  |$\mu$| m, [N  ii ] 122  |$\mu$| m, [O  iii ] 88  |$\mu$| m, [O  iii ] 52  |$\mu$| m, [O  i ] 63  |$\mu$| m and the absorption doublet of OH at 119  |$\mu$| m, at high fidelity. We find that the average electron densities traced by the [N  ii ] and [O  iii ] lines are higher than the average values in local star-forming galaxies and ULIRGs, using the same tracers. From the [N  ii ]/[C  ii ] and [O  i ]/[C  ii ] ratios, we find that the [C  ii ] emission is likely dominated by the photodominated regions (PDR), instead of by ionized gas or large-scale shocks. [ABSTRACT FROM AUTHOR]

We describe an update to the Herschel-Spectral and Photometric Imaging Receiver (SPIRE) Fourier-transform spectrometer (FTS) calibration for extended sources, which incorporates a correction for the frequency-dependent far-field feedhorn efficiency, ηff. This significant correction affects all FTS extended-source calibrated spectra in sparse or mapping mode, regardless of the spectral resolution. Line fluxes and continuum levels are underestimated by factors of 1.3-2 in thespectrometer long wavelength band (447-1018 GHz; 671-294 μm) and 1.4-1.5 in the spectrometer short wavelength band (944-1568 GHz; 318-191 μm). The correctionwas implemented in the FTS pipeline version 14.1 and has also been described in the SPIRE Handbook since 2017 February. Studies based on extended-source calibrated spectra produced prior to this pipeline version should be critically reconsidered using the current products available in the Herschel Science Archive. Once the extended-source calibrated spectra are corrected for ηff, the synthetic photometry and the broad-band intensities from SPIRE photometer maps agree within 2-4 per cent - similar levels to the comparison of point-source calibrated spectra and photometry from point-source calibrated maps. The two calibration schemes for the FTS are now self-consistent: the conversion between the corrected extended-source and point-source calibrated spectra can be achieved with the beam solid angle and a gain correction that accounts for the diffraction loss. [ABSTRACT FROM AUTHOR]

An experimental study using Mach-Zehnder interferometer has been carried out to investigate the heat transfer from an isothermal horizontal circular cylinder, which is exposed to an air slot jet at different angles of jet impingement. A square edged nozzle is mounted parallel with the cylinder axis and jet flow impinges on the side of the cylinder at angles Θ = 0°, 30°, 60° and 90°. The Reynolds number varied from 240 to 1900 while the Grashof number and slot- to cylinder-spacing is kept constant at Gr = 22,300 and H/w = 7 respectively. The Richardson number varied from 0.006 to 0.4. The flow field is greatly influenced by the slot exit velocity and the buoyancy force due to density change. The local Nusselt number around the cylinder has been calculated using the infinite fringe interferograms at 10° intervals. Average Nusselt number shows that heat transfer is decreased when the angle of jet impingement is increased . [ABSTRACT FROM AUTHOR]

A systematic programme of calibration observations was carried out to monitor the performance of the Spectral and Photometric Imaging REceiver (SPIRE) Fourier Transform Spectrometer (FTS) instrument on board the Herschel Space Observatory. Observations of planets (including the prime point-source calibrator, Uranus), asteroids, line sources, dark sky and cross-calibration sources were made in order to monitor repeatability and sensitivity, and to improve FTS calibration. We present a complete analysis of the full set of calibration observations and use them to assess the performance of the FTS. Particular care is taken to understand and separate out the effect of pointing uncertainties, including the position of the internal beam steering mirror for sparse observations in the early part of the mission. The repeatability of spectral-line centre positions is <5 km s-1, for lines with signal-to-noise ratios >40, corresponding to <0.5-2.0 per cent of a resolution element. For spectral-line flux, the repeatability is better than 6 per cent, which improves to 1-2 per cent for spectra corrected for pointing offsets. The continuum repeatability is 4.4 per cent for the SPIRE Long Wavelength spectrometer (SLW) band and 13.6 per cent for the SPIRE Short Wavelength spectrometer (SSW) band, which reduces to ~1 per cent once the data have been corrected for pointing offsets. Observations of dark sky were used to assess the sensitivity and the systematic offset in the continuum, both of which were found to be consistent across the FTS-detector arrays. The average point-source calibrated sensitivity for the centre detectors is 0.20 and 0.21 Jy [1σ; 1 h], for SLW and SSW. The average continuum offset is 0.40 Jy for the SLW band and 0.28 Jy for the SSW band. [ABSTRACT FROM AUTHOR]

Context. The determination of the physical conditions in molecular clouds is a key step towards our understanding of their formation and evolution of associated star formation. We investigate the density, temperature, and column density of both dust and gas in the photodissociation regions (PDRs) located at the interface between the atomic and cold molecular gas of the NGC 7023 reflection nebula. We study how young stars affect the gas and dust in their environment. Aims. Several Herschel Space Telescope programs provide a wealth of spatial and spectral information of dust and gas in the heart of PDRs. We focus our study on Spectral and Photometric Image Receiver (SPIRE) Fourier-Transform Spectrometer (FTS) fully sampled maps that allow us for the first time to study the bulk of cool/warm dust and warm molecular gas (CO) together. In particular, we investigate if these populations spatially coincide, if and how the medium is structured, and if strong density and temperature gradients occur, within the limits of the spatial resolution obtained with Herschel. Methods. The SPIRE FTS fully sampled maps at different wavelengths are analysed towards the northwest (NW) and the east (E) PDRs in NGC 7023. We study the spatial and spectral energy distribution of a wealth of intermediate rotational 12CO 4 ⩽ Ju ⩽ 13 and 13CO 5 ⩽ Ju ⩽ 10 lines. A radiative transfer code is used to assess the gas kinetic temperature, density, and column density at different positions in the cloud. The dust continuum emission including Spitzer, the Photoconductor Array Camera and Spectrometer (PACS), and SPIRE photometric and the Institute for Radio Astronomy in the Millimeter Range (IRAM) telescope data is also analysed. Using a single modified black body and a radiative transfer model, we derive the dust temperature, density, and column density. Results. The cloud is highly inhomogeneous, containing several irradiated dense structures. Excited 12CO and 13CO lines and warm dust grains localised at the edge of the dense structures reveal high column densities of warm/cool dense matter. Both tracers give a good agreement in the local density, column density, and physical extent, leading to the conclusion that they trace the same regions. The derived density profiles show a steep gradient at the cloud edge reaching a maximum gas density of 105-106 cm-3 in the PDR NGC 7023 NW and 104-105 cm-3 in the PDR NGC 7023 E and a subsequent decrease inside the cloud. Close to the PDR edges, the dust temperature (30 K and 20 K for the NW and E PDRs, respectively) is lower than the gas temperature derived from CO lines (65-130 K and 45-55 K, respectively). Further inside the cloud, the dust and gas temperatures are similar. The derived thermal pressure is about 10 times higher in NGC 7023 NW than in NGC 7023 E. Comparing the physical conditions to the positions of known young stellar object candidates in NGC 7023 NW, we find that protostars seem to be spatially correlated with the dense structures. Conclusions. Our approach combining both dust and gas delivers strong constraints on the physical conditions of the PDRs. We find dense and warm molecular gas of high column density in the PDRs. [ABSTRACT FROM AUTHOR]

The Herschel Spectral and Photometric REceiver (SPIRE) instrument consists of an imaging photometric camera and an imaging Fourier Transform Spectrometer (FTS), both operating over a frequency range of ∼450–1550 GHz. In this paper, we briefly review the FTS design, operation, and data reduction, and describe in detail the approach taken to relative calibration (removal of instrument signatures) and absolute calibration against standard astronomical sources. The calibration scheme assumes a spatially extended source and uses the Herschel telescope as primary calibrator. Conversion from extended to point-source calibration is carried out using observations of the planet Uranus. The model of the telescope emission is shown to be accurate to within 6 per cent and repeatable to better than 0.06 per cent and, by comparison with models of Mars and Neptune, the Uranus model is shown to be accurate to within 3 per cent. Multiple observations of a number of point-like sources show that the repeatability of the calibration is better than 1 per cent, if the effects of the satellite absolute pointing error (APE) are corrected. The satellite APE leads to a decrement in the derived flux, which can be up to ∼10 per cent (1 σ) at the high-frequency end of the SPIRE range in the first part of the mission, and ∼4 per cent after Herschel operational day 1011. The lower frequency range of the SPIRE band is unaffected by this pointing error due to the larger beam size. Overall, for well-pointed, point-like sources, the absolute flux calibration is better than 6 per cent, and for extended sources where mapping is required it is better than 7 per cent. [ABSTRACT FROM AUTHOR]

The Spectral and Photometric Imaging Receiver (SPIRE) on the European Space Agency's Herschel Space Observatory utilizes a pioneering design for its imaging spectrometer in the form of a Fourier Transform Spectrometer (FTS). The standard FTS data reduction and calibration schemes are aimed at objects with either a spatial extent that is much larger than the beam size or a source that can be approximated as a point source within the beam. However, when sources are of intermediate spatial extent, neither of these calibrations schemes is appropriate and both the spatial response of the instrument and the source's light profile must be taken into account and the coupling between them explicitly derived. To that end, we derive the necessary corrections using an observed spectrum of a fully extended source with the beam profile and considering the source's light profile. We apply the derived correction to several observations of planets and compare the corrected spectra with their spectral models to study the beam coupling efficiency of the instrument in the case of partially extended sources. We find that we can apply these correction factors for sources with angular sizes up to ϑD ∼ 17″. We demonstrate how the angular size of an extended source can be estimated using the difference between the subspectra observed at the overlap bandwidth of the two frequency channels in the spectrometer, at 959 < ? < 989 GHz. Using this technique on an observation of Saturn, we estimate a size of 17.2″, which is 3% larger than its true size on the day of observation. Finally, we show the results of the correction applied on observations of a nearby galaxy, M82, and the compact core of a Galactic molecular cloud, Sgr B2. [ABSTRACT FROM AUTHOR]

The D/H ratio in cometary water is believed to be an important indicator of the conditions under which icy planetesimals formed and can provide clues to the contribution of comets to the delivery of water and other volatiles to Earth. Available measurements suggest that there is isotopic diversity in the comet population. The Herschel Space Observatory revealed an ocean-like ratio in the Jupiter-family comet 103P/Hartley 2, whereas most values measured in Oort-cloud comets are twice as high as the ocean D/H ratio. We present here a new measurement of the D/H ratio in the water of an Oort-cloud comet. HDO, H2O, and lines were observed with high signal-to-noise ratio in comet C/2009 P1 (Garradd) using the Herschel HIFI instrument. Spectral maps of two water lines were obtained to constrain the water excitation. The D/H ratio derived from the measured H216O and HDO production rates is (2.06 ± 0.22) × 10-4. This result shows that the D/H in the water of Oort-cloud comets is not as high as previously thought, at least for a fraction of the population, hence the paradigm of a single, archetypal D/H ratio for all Oort-cloud comets is no longer tenable. Nevertheless, the value measured in C/2009 P1 (Garradd) is significantly higher than the Earth's ocean value of 1.558 × 10-4. The measured 16O/18O ratio of 523 ± 32 is, however, consistent with the terrestrial value. [ABSTRACT FROM AUTHOR]

Aims. We provide an extensive new sub-millimetre survey of the trace gas composition of Saturn's atmosphere using the broad spectral range (15-51 cm-1) and high spectral resolution (0.048 cm-1) offered by Fourier transform spectroscopy by the Herschel/SPIRE instrument (Spectral and Photometric Imaging REceiver). Observations were acquired in June 2010, shortly after equinox, with negligible contribution from Saturn's ring emission. Methods. Tropospheric temperatures and the vertical distributions of phosphine and ammonia are derived using an optimal estimation retrieval algorithm to reproduce the sub-millimetre data. The abundance of methane, water and upper limits on a range of different species are estimated using a line-by-line forward model. Results. Saturn's disc-averaged temperature profile is found to be quasi-isothermal between 60 and 300 mbar, with uncertainties of 7 K due to the absolute calibration of SPIRE. Modelling of PH3 rotational lines confirms the vertical profile derived in previous studies and shows that negligible PH3 is present above the 10- to 20-mbar level. The upper tropospheric abundance of NH3 appears to follow a vapour pressure distribution throughout the region of sensitivity in the SPIRE data, but the degree of saturation is highly uncertain. The tropospheric CH4 abundance and Saturn's bulk C/H ratio are consistent with Cassini studies. We improve the upper limits on several species (H2S, HCN, HCP and HI); provide the first observational constraints on others (SO2, CS, methanol, formaldehyde, CH3Cl); and confirm previous upper limits on HF, HCl and HBr. Stratospheric emission from H2O is suggested at 36.6 and 38.8 cm-1 with a 1σ significance level, and these lines are used to derive mole fractions and column abundances consistent with ISO and SWAS estimations a decade earlier. [ABSTRACT FROM AUTHOR]

Context. The energetics in photo-dissociation regions (PDRs) are mainly regulated by the balance between the heating from the photo-electric effect acting on dust grains, and the cooling via the copious emission of photons in far-infrared lines. The Orion Bar is a luminous and nearby PDR, which presents to the observer an ideal edge-on orientation in which to study this energy balance. Spatially resolved studies of such a nearby system are essential as they enable us to characterise the physical processes that control the energetics of the regions and can serve as templates for distant systems where these processes cannot be disentangled. Aims. We characterise the emission of the far-infrared fine-structure lines of [C II] (158 μm), [OI] (63 and 145 μm), and [N II] (122 μm) that trace the gas local conditions, via spatially resolved observations of the Orion Bar. The observed distribution and variation of the lines are discussed in relation to the underlying geometry and linked to the energetics associated with the Trapezium stars. Methods. Herschel/PACS observations are used to map the spatial distribution of these fine-structure lines across the Bar, with a spatial resolution between 4" and 11" and covering a total square area of about 120" × 105" . The spatial profile of the emission lines are modelled using the radiative transfer code Cloudy. Results. The Herschel observations reveal in unprecedented detail the morphology of the Bar. The spatial distribution of the [CII] line coincides with that of the [OI] lines. The [N II] line peaks closer to the ionising star than the other three lines, but with a small region of overlap. We can distinguish several knots of enhanced emission within the Bar indicating the presence of an inhomogenous and structured medium. The emission profiles cannot be reproduced by a single PDR, clearly indicating that, besides the Bar, there is a significant contribution from additional PDR(s) over the area studied. The combination of both the [NII] and [OI] 145 μm lines can be used to estimate the [C II] emission and distinguish between its ionised or neutral origin.We have calculated how much [CII] emission comes from the neutral and ionised region, and find that at least ∼82% originates from the photo-dissocciation region. Together, the [C II] 158 μm and [OI] 63 and 145 μm lines account for ∼90% of the power emitted by the main cooling lines in the Bar (including CO, H2, etc.), with [O I] 63 μm alone accounting for 72% of the total. [ABSTRACT FROM AUTHOR]

Heat transfer to horizontal cylinders immersed in fluidized beds has been extensively studied, but mainly in the context of heat transfer to boiler tubes in coal-fired beds. As a result, most correlations in the literature have been derived for cylinders of 25-50 mm diameter in vigorously fluidizing beds. In recent years, fluidized bed heat treating furnaces fired by natural gas have become increasingly popular, particularly in the steel wire manufacturing industry. These fluidized beds typically operate at relatively low fluidizing rates (G/Gmf<5) and with small diameter wires (1-6 mm). Nusselt number correlations developed based on boiler tube studies do not extrapolate down to these small size ranges and low fluidizing rates. In order to obtain reliable Nusselt number data for these size ranges, an experimental investigation has been undertaken using two heat treating fluidized beds; one a pilot-scale industrial unit and the other a lab-scale (300 mm diameter) unit. Heat transfer measurements were obtained using resistively heated cylindrical samples ranging from 1.3 to 9.5 mm in diameter at fluidizing rates ranging from approximately 0.5xgmf (packed bed condition) to over 10xgmf using aluminum oxide sand particles ranging from dp=145-330 µm (50-90 grit). It has been found that for all cylinder sizes tested, the Nusselt number reaches a maximum near 2xgmf, then remains relatively steady (±5-10%) to the maximum fluidizing rate tested, typically 8-12xgmf. A correlation for maximum Nusselt number is developed. [ABSTRACT FROM AUTHOR]

SPIRE, the Spectral and Photometric Imaging Receiver, is Herschel's submillimetre camera and spectrometer. It comprises a three-band imaging photometer operating at 250, 350 and 500 μm, and an imaging Fourier Transform Spectrometer (FTS) covering 194-672 μm. The design of SPIRE is described, and the expected scientific performance is summarised, based on modelling and flight instrument test results. [ABSTRACT FROM AUTHOR]