Middle Channels Research Articles

Angular Normalization of Land Surface Temperature and Emissivity Using Multiangular Middle and Thermal Infrared Data

This paper aimed at the case of nonisothermal pixels and proposed a daytime temperature-independent spectral indices (TISI) method to retrieve directional emissivity and effective temperature from daytime multiangular observed images in both middle and thermal infrared (MIR and TIR) channels by combining the kernel-driven bidirectional reflectance distribution function (BRDF) model and the TISI method. Four groups of angular observations and two groups of MIR and TIR channels with narrow and broad bandwidths were used to investigate the influence of angular observations and bandwidth on the retrieval accuracy. Model sensitivity analysis indicated that the new method can generally obtain directional emissivity and temperature with an error less than 0.015 and 1.5 K if the noise included in the measured directional brightness temperature (DBT) and atmospheric data was no more than 1.0 K and 10%, respectively. The analysis also indicated that 1) large-angle intervals among the angular observations and a larger viewing zenith angle, with respect to nadir direction, can improve the retrieval accuracy because those angle conditions can result in significant difference for components' fractions and DBT under different viewing directions; 2) narrow channels can produce better results than broad channels. The new method was finally applied to a multiangular MIR and TIR data set acquired by an airborne system, and a modified kernel-driven BRDF model was used for angular normalization to the surface temperature for the first time. The difference of the retrieved emissivity and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) emissivity was found to be approximately 0.012 in the study area.

Discrete geometry optimization for reducing flow non-uniformity, asymmetry, and parasitic minor loss pressure drops in Z-type configurations of fuel cells

Parallel channel configurations, such as Z-type, used to distribute reagents in planar fuel cells provide lower overall pressure drop as compared to other channel designs. However, due to their inherent characteristics, flow maldistribution in parallel configurations is commonly observed and leads to starvation of reagents in middle channels. In addition, the Reynolds number dependent minor losses at branching tee junctions may cause asymmetric flow non-uniformity and reagent imbalance between the cathode and anode. Herein, we present a universal and simple optimization method to simultaneously reduce flow maldistribution, asymmetry, and parasitic pressure in Z-type parallel configurations of fuel cells or fuel cell stacks that has improved scalability relative to previous methods. A discrete model's governing equations were reduced to yield geometric ratios between headers. Increasing header widths to satisfy these ratios reduced flow maldistribution without modifying parallel channel geometry as validated by computation fluid dynamics (CFD) simulations. Furthermore, decreased Reynolds numbers throughout the headers reduced minor pressure drops and flow distribution asymmetry. We offer several methods to reduce the optimized geometry's footprint, including an adaptation of the discontinuous design.

Correction: Mouse Middle Ear Ion Homeostasis Channels and Intercellular Junctions

The version of Figure 1 that exists in the article is incorrect. The correct version can be found here:

A novel microfluidic platform with stable concentration gradient for on chip cell culture and screening assays

In this work a novel microfluidic platform for cell culture and assay is developed. On the chip a static cell culture region is coupled with dynamic fluidic nutrition supply structures. The cell culture unit has a sandwich structure with liquid channels on the top, the cell culture reservoir in the middle and gas channels on the bottom. Samples can be easily loaded into the reservoir and exchange constantly with the external liquid environment by diffusion. Since the flow direction is perpendicular to the liquid channel on the top of the reservoir, the cells in the reservoir are shielded from shear-force. By assembling the basic units into an array, a steady concentration gradient can be generated. Cell culture models both for continuous perfusion and one-off perfusion were established on the chip. Both adherent and suspended cells were successfully cultured on the chip in 2D and 3D culture modes. After culturing, the trapped cells were recovered for use in a later assay. As a competitive candidate for a standard cell culture and assay platform, this chip is also adaptable for cytotoxicity and cell growth assays.

Application of 15N–18O double stable isotope tracer technique in an agricultural nonpoint polluted river of the Yangtze Delta Region

One strategy to combat nitrate (NO3-N) contamination in rivers is to understand its sources. NO3-N sources in the East Tiaoxi River of the Yangtze Delta Region were investigated by applying a (15)N-(18)O dual isotope approach. Water samples were collected from the main channel and from the tributaries. Results show that high total N and NO3-N are present in both the main channel and the major tributaries, and NO3-N was one of the most important N forms in water. Analysis of isotopic compositions (δ (18)O, δD) of water suggests that the river water mainly originated from three tributaries during the sampling period. There was a wide range of δ (15)N-NO3 (-1.4 to 12.4 ‰) and a narrow range of δ (18)O-NO3 (3.7 to 9.0 ‰) in the main channel waters. The δ (15)N and δ (18)O-NO3 values in the upper, middle, and lower channels along the river were shifted as 8.2, 3.5, and 9.5 ‰, and 9.0, 4.2, and 6.0 ‰, respectively. In the tributary South Tiao, the δ (15)N and δ (18)O-NO3 values were as high as 9.5 and 7.0 ‰, while in the tributaries Mid Tiao and North Tiao, NO3-N in most of the samples had relatively low δ (15)N and δ (18)O-NO3 values from 2.3 to 7.5 ‰ and 4.7 to 7.0 ‰, separately. Our results also suggest that the dual isotope approach can help us develop the best management practice for relieving NO3-N pollution in the rivers at the tributary scale.

Mouse Middle Ear Ion Homeostasis Channels and Intercellular Junctions

HypothesisThe middle ear contains homeostatic mechanisms that control the movement of ions and fluids similar to those present in the inner ear, and are altered during inflammation.BackgroundThe normal middle ear cavity is fluid-free and air-filled to allow for effective sound transmission. Within the inner ear, the regulation of fluid and ion movement is essential for normal auditory and vestibular function. The same ion and fluid channels active in the inner ear may have similar roles with fluid regulation in the middle ear.MethodsMiddle and inner ears from BALB/c mice were processed for immunohistochemistry of 10 specific ion homeostasis factors to determine if similar transport and barrier mechanisms are present in the tympanic cavity. Examination also was made of BALB/c mice middle ears after transtympanic injection with heat-killed Haemophilus influenza to determine if these channels are impacted by inflammation.ResultsThe most prominent ion channels in the middle ear included aquaporins 1, 4 and 5, claudin 3, ENaC and Na+,K+-ATPase. Moderate staining was found for GJB2, KCNJ10 and KCNQ1. The inflamed middle ear epithelium showed increased staining due to expected cellular hypertrophy. Localization of ion channels was preserved within the inflamed middle ear epithelium.ConclusionsThe middle ear epithelium is a dynamic environment with intrinsic mechanisms for the control of ion and water transport to keep the middle ear clear of fluids. Compromise of these processes during middle ear disease may underlie the accumulation of effusions and suggests they may be a therapeutic target for effusion control.

Application of spectral decomposition and seismic attributes to understand the structure and distribution of sand reservoirs within Tertiary rift basins of the Gulf of Thailand

The Tertiary rift basins in the Gulf of Thailand are the major hydrocarbon producing areas of Thailand. The reservoirs in these basins are predominantly Lower to Middle Miocene fluvial channels and overbank sands and these reservoirs are segmented due to post-depositional faulting (Racey, 2011). There are small closely spaced sealing faults, which compartmentalize the sand reservoirs and are not easy to map on conventional full spectrum seismic data. This fault system is oblique to the regional north-south extensional fault system and is related to graben shifts/transfer zones associated with changes in dip of graben provinces and zig-zag map pattern of the regional north-south faults (Kornsawan and Morley, 2002). Most wells until now have been drilled on structures along the faults and it is common to encounter different sand facies with different fluid contents in closely spaced wells at the same depth intervals. Because of these structural and stratigraphic complexities, it is required to develop geophysical workflows to better image faults related with graben shifts and map the reservoir sands in the area. In this study, we analyzed a 3D seismic data set over a gas field in the Pattani Basin (Figure 1) where we applied a spectral decomposition technique to resolve these exploration issues. Moreover, semblance and sweetness attributes were also calculated to assist in the fault and sand detection, respectively.

Experimental study of temperature distribution on anodic surface of MEA inside a PEMFC with parallel channels flow bed

The temperature distribution on membrane electrode assembly (MEA) surface is very important to the performance, lifetime and reliability of proton exchange membrane fuel cells (PEMFCs). With thermal imaging technology and the self-designed fuel cell, the measurement of whole temperature fields on anode MEA surface under parallel channels was achieved experimentally at non-humidification conditions. The results show that the temperatures in the middle channels are higher than that in other channels and the temperatures in the middle section appear higher than that in other sections for each channel. The non-uniformity of flow distribution in parallel channel is one of the key factors causing the non-uniformity of temperature field. It implies that the uniformity of flow field should be concerned for improving the uniformity of temperature distribution. Experimental results also appear that the temperature of MEA, non-uniformity of temperature distribution on the MEA surface and the fuel cell temperature increase with the loaded current density.

Line Break Situations in International Rugby

The team who scored the most tries won 81% of all Rugby World Cup matches in 2007. However, there is little research published into events that lead to tries being scored from open play and especially the line break situation. There were a total of 47 line breaks recorded during 11 matches, 51% of which resulted in a try being scored, 30% of which no try was scored but possession was retained and 19% resulted in possession being lost. Most of the line breaks occurred within the attacking half of the field (55%) with 45% occurring from within the defending half. 89% of line break situations occurred towards the centre and left side of the field in the midfield zones B and C. 68% of the line breaks were created by the winning teams and these originated predominantly from the middle and left channels of the attacking half of the pitch. Losing teams relied on interception line breaks for their tries. The players most frequently observed making the line breaks were the left wing (17%), the fullback (13%.) Line breaks were an effective source of tries with an average of 2 tries being scored from a line break every match.

Investigating the spatial distribution of water levels in the Mackenzie Delta using airborne LiDAR

AbstractAirborne light detection and ranging (LiDAR) data were used to map water level (WL) and hydraulic gradients (δH/δx) in the Mackenzie Delta. The LiDAR WL data were validated against eight independent hydrometric gauge measurements and demonstrated mean offsets from − 0·22 to + 0·04 m (σ< 0·11). LiDAR‐based WL gradients could be estimated with confidence over channel lengths exceeding 5–10 km where the WL change exceeded local noise levels in the LiDAR data. For the entire Delta, the LiDAR sample coverage indicated a rate of change in longitudinal gradient (δ2H/δx) of 5·5 × 10−10 m m−2; therefore offering a potential means to estimate average flood stage hydraulic gradient for areas of the Delta not sampled or monitored. In the Outer Delta, within‐channel and terrain gradient measurements all returned a consistent estimate of − 1 × 10−5 m m−1, suggesting that this is a typical hydraulic gradient for the downstream end of the Delta. For short reaches (<10 km) of the Peel and Middle Channels in the middle of the Delta, significant and consistent hydraulic gradient estimates of − 5 × 10−5 m m−1 were observed. Evidence that hydraulic gradients can vary over short distances, however, was observed in the Peel Channel immediately upstream of Aklavik. A positive elevation anomaly (bulge) of > 0·1 m was observed at a channel constriction entering a meander bend, suggesting a localized modification of the channel hydraulics. Furthermore, water levels in the anabranch channels of the Peel River were almost 1 m higher than in Middle Channel of the Mackenzie River. This suggests: (i) the channels are elevated and have shallower bank heights in this part of the delta, leading to increased cross‐delta and along‐channel hydraulic gradients; and/or (ii) a proportion of the Peel River flow is lost to Middle Channel due to drainage across the delta through anastamosing channels. This study has demonstrated that airborne LiDAR data contain valuable information describing Arctic river delta water surface and hydraulic attributes that would be challenging to acquire by other means. Copyright © 2011 John Wiley & Sons, Ltd.

Pressure Drop in Multi-Parallel Channels of Corrugated Plate Steam Condensers

An experimental investigation has been carried out to find the pressure difference of the process of steam condensation across the port to channel in plate heat exchangers. In the present study, low corrugation angle (30°) plates have been used for different number of channels, namely, 10 and 80. The process steam entered at 1 bar with a small degree of superheat. Water has been used as the cold fluid. The pressure probes are inserted through the plate gasket into both the inlet and exit ports of the channel. The pressure drop of the process steam has been measured and recorded at the first, middle, and last channels at different flow and exit conditions for each plate package of the heat exchanger. Also, the overall pressure drop has been measured at different conditions at the outlet of the process steam, i.e., full and partial condensation. The pressure drop measurements have indicated that there is a considerable variation in pressure drop from the first channel to the last channel due to flow maldistribution. The experimental data has been analyzed to show how the flow maldistribution affects the pressure drop of a plate condenser.

Highly porous and macrovoid-free PVDF hollow fiber membranes for membrane distillation by a solvent-dope solution co-extrusion approach

Highly porous and macrovoid-free PVDF hollow fiber membranes are of great interest for membrane contactor applications such as sea water desalination by membrane distillation in order to enhance the flux and long term stability of the process. For the first time in this paper, porous PVDF hollow fiber membranes with high outer surface porosity were fabricated by applying a two-phase flow consisting of a solvent and a dope solution in the air-gap region of spinning through a non-solvent induced phase separation process (NIPS). In this approach, the dope solution and the N-methylpyrrolidone (NMP) solvent were co-discharged from the middle and outer channels of a triple orifice spinneret, respectively. Then, the two-phase flow went through an air-gap region and finally entered the coagulation bath. It was observed that the introduction of the two-phase flow greatly increased the outer surface porosity of the PVDF fibers and eliminated the formation of macrovoids in the cross-section of the fibers as well. It was also found that the energy efficiency and the flux of the fibers spun through the solvent-dope solution co-exterusion were two to three times higher than the standard dry jet wet-spun fibers. A water vapor flux as high as 67 kg/(m 2 h) at 80 °C was obtained through the newly spun fibers.

A New Model-Based Algorithm for Optimizing the MPEG-AAC in MS-Stereo

In this paper, a new model-based algorithm for optimizing the MPEG-advanced audio coder (AAC) in MS-stereo mode is presented. This algorithm is an extension to stereo signals of prior work on a statistical model of quantization noise. Traditionally, MS-stereo coding approaches replace the left (l) and right (R) channels by the middle (M) and sides (S) channels, each channel being independently processed, almost like a monophonic signal. In contrast, our method proposes a global approach for coding both channels in the same process. A model for the quantization error allows us to tune the quantizers on channels M and S with respect to a distortion constraint on the reconstructed channels L and R as they will appear in the decoder. This approach leads to a more efficient perceptual noise-shaping and avoids using complex psychoacoustic models built on the M and S channels. Furthermore, it provides a straightforward scheme to choose between LR and MS modes in each subband for each frame. Subjective listening tests prove that the coding efficiency at a medium bitrate (96 kbits/s for both channels) is significantly better with our algorithm than with the standard algorithm, without increase of complexity.

Steam Condensation in Parallel Channels of Plate Heat Exchangers — An Experimental Investigation

An experimental investigation has been carried out to find the pressure difference of the process of steam condensation across the port to channel in plate heat exchangers. In the present study, low corrugation angle (30°) plates have been used for different number of channels, namely, 10 and 80. The process steam entered at 1 bar with a small degree of superheat. Water has been used as the cold fluid. The pressure probes are inserted through the plate gasket into both the inlet and exit ports of the channel. The pressure drop of the process steam has been measured and recorded at the first, middle, and last channels at different flow and exit conditions for each plate package of the heat exchanger. Also, the overall pressure drop has been measured at different conditions at the outlet of the process steam, i.e., full and partial condensation. The pressure drop measurements have indicated that there is a considerable variation in pressure drop from the first channel to the last channel due to flow maldistribution. The experimental data has been analyzed to show how the flow maldistribution affects the pressure drop of a plate condenser. (Less)

Visualisation of water droplets during the operation of PEM fuel cells

A transparent proton exchange membrane fuel cell (PEMFC) has been designed to enable visualisation of water droplets during its operation. Images of the formation of droplets on the surface of the gas diffusion layer (GDL) on its cathode side, which result in water accumulation and blockage to the airflow channels, were recorded using a CCD camera. Measurement of the cell current and droplet characterisation have been carried out simultaneously and the effect of the airflow and external resistive load has been quantified. The droplet images show that water accumulation occurs first in the middle channels of a serpentine reactant-flow fuel cell design and that no droplets are formed at the bends of the flow channels. Water blockage to the airflow path was caused by the overlapping of two land-touching droplets developing on each side of the channel. Flooding was found to be more susceptible to the airflow than the other test operating conditions.

Size-based microfluidic enrichment of neonatal rat cardiac cell populations

Native heart consists of myocytes and non-myocytes. We demonstrate here the feasibility of a size-based microfluidic separation of myocytes and non-myocytes from the neonatal rat myocardium. The device consists of a middle channel (50 microm wide, 200 microm tall, and 4 cm long) connected to adjacent side channels by microsieves (80 microm wide, 5 microm tall and 40 microm in length). The side channels increase in width in a flared shape along the length of the device to ensure constant pressure gradient across all sieves. In the first step, non-myocytes were removed from the myocytes by a conventional pre-plating method for 75 min. Subsequently, the non-myocytes were further enriched in a microfluidic device at 20 microl/min. We demonstrated that the cells in the middle and side channels maintained viability during sorting and the ability to attach and grow in culture. Upon culture for 48 h cardiomyocytes from the reservoir (control) and middle channel stained positive for cardiac Troponin I, exhibited a well developed contractile apparatus and contracted spontaneously and in response to electrical field stimulation. Most of the cells in the side channel expressed a non-myocyte marker vimetin. Fluorescent activated cell sorting indicated significant enrichment in the side channel (p < 0.001) for non-myocytes. Original cell suspension had a bimodal cell size distribution with the peaks in the range from 7-9 microm and 15-17 microm. Upon cell sorting the distribution was Gaussian in both side channel and middle channel with the peaks in the range 7-9 microm and 9-11 microm respectively, indicating that the separation by size occurred.

An experimental investigation of the port flow maldistribution in small and large plate package heat exchangers

An experimental investigation has been carried out to find the flow and the pressure difference across the port to channel in plate heat exchangers for a wide range of Reynolds number, 1000–17 000. In the present study, low corrugation angle plates have been used for different number of channels, namely, 20 and 80. Water has been used as working fluid for both hot and cold fluids. The pressure probes are inserted through the plate gasket into both the inlet and exit ports of the channel. The pressure drop is recorded at the first, middle and last channels for each plate package of the heat exchanger. Also, the overall pressure drop has been measured for various flow rates. This overall pressure drop is a function of the flow rate, the cross-sectional area ratio of channel to port and number of channels per fluid. A simplified non-dimensional channel velocity has been suggested based on the channel pressure drop and the mean channel pressure drop of plate package, to measure the deviation of the particular channel flow rate from the mean channel flow rate. The results indicated that the flow maldistribution increases with increasing overall pressure drop in the plate heat exchangers. The experimental results are verified with M.K. Bassiouny and H. Martin’s [Chemical Engineering Science 39(4) (1984) 693 and 701] analytical results.

Interannual co‐variability of tropical temperature and humidity: A comparison of model, reanalysis data and satellite observation

We use a 20‐year record of HIRS radiance measurements to evaluate the fidelity of interannual co‐variability of tropical humidity and temperature in the reanalyses and GFDL AM2 simulations. Large inconsistencies between the NCEP and ECMWF reanalyses are found as are disagreements between the reanalyses and AM2 simulations. The largest discrepancies occur in the middle and upper troposphere where the NCEP and ECMWF tropical‐mean relative humidity anomalies are found to be negatively correlated. When compared to HIRS dataset, NCEP is found to have unrealistically large interannual variablity in both the upper (6.7 μm) and middle (7.3 μm) tropospheric humidity channels. The radiance anomalies simulated from AM2 model output are shown to agree well with those observed by HIRS. These results support the validity of the strong coupling between temperature and humidity variations simulated in the GFDL AM2 and highlight the need to improve the representation of interannual variations of humidity in the reanalyses.

Global climatology of inertial instability and Rossby wave breaking in the stratosphere

Climatologies using United Kingdom Met Office assimilated analyses from November 1991 through March 2004 are used to juxtapose the evolution of inertial instability and Rossby wave breaking in longitude, latitude, altitude, and time. The results for the upper and middle stratosphere indicate deep poleward and eastward channels of higher inertial instability frequency extending from the central equatorial Pacific in both winter hemispheres. These corridors of enhanced inertial instability frequency are generally found just poleward of regions of frequent Rossby wave breaking, a result confirmed with a case study drawn from the period of the climatology. Both of these patterns are evident from the stratopause downward into the middle stratosphere, with the frequency of events diminishing with decreasing altitude. Analysis of interannual variability of Rossby wave breaking and inertial instability in the middle stratosphere channels confirms a correlation between them, as well as a possible quasi‐biennial oscillation signal in the early years of the climatology. In the lower stratosphere a channel of enhanced inertial instability frequency exists near east Asia in Northern Hemisphere winter, again just poleward of a Rossby wave breaking maximum. These results generally agree closely in space and time with, and significantly extend, the relatively few previously published climatologies and case studies of episodes of Rossby wave‐triggered inertial instability for the stratosphere.

Ancient sand-rich submarine fans: depositional systems, models, identification, and analysis

Sand-rich submarine fans are radial or curved in plan view depending on the slope of the basin floor. They occur isolated or in coalescing systems. The fans' average lateral extent measures close to 25 km and their thickness usually less than 300 m. The thickness of outer fan sequences averages around 120 m and that of middle fan successions around 160 m. Rarely reported inner fan sequences have a maximum thickness of 80 m. The formation of sand-rich fans is closely related to tectonic activity. Their sediment is coarse-grained and compositionally immature as indicated by significant feldspar content due to close provenance and rapid transport by short rivers with a steep gradient controlled by tectonism. Tectonic activity also provides for narrow shelves making the fans relatively insensitive to sealevel changes. Formation of sand-rich fans typically occurs in restricted continental basins. The tectonic settings are highly variable. Sand-rich fans typically receive their sediment through submarine canyons which intercept sand from longshore drift and/or are fed more or less directly by regional rivers. The type of ancient fan system (radial, curved, isolated, coalescing) may be identified through paleocurrent map plots, facies map sketches, recognition of lateral thickness variations and sediment influx centers, as well as lateral bed correlations defining the minimum fan extent. Important in distinguishing different environments of ancient fans are detailed measured sections, their comparison and correlation. Channelized inner fan and middle fan deposits may be distinguished from the unchannelized outer fan successions through bed correlation tests which reflect their different stratigraphic architectures and bedding patterns. Bedding in outer fan deposits (lobes) is relatively simple, parallel, and regular. The lateral bed continuity is relatively high. Channel fills, especially those of middle fan distributary channels, display a complicated bedding pattern with vertical and lateral random distribution of channel fills, axial erosion, and bed convergence towards the channel margins. Channel fills exhibit only linear bed continuity. Thus, the probability in carrying out local to regional scale lateral bed correlations is almost exclusively limited to outer fan deposits. The measured sections will help further distinguish fan environments by revealing: (1) different facies associations in outer fan sequences (mainly B, C and D) and middle fan successions (mainly A, B, C, D, and channel margin facies); (2) greater average bed and layer thicknesses in middle fan as opposed to outer fan successions (“bed” and “layer” as used herein); (3) more frequent amalgamation surfaces in channel fills than in unchannelized outer fan deposits; (4) more frequent tabular amalgamation surfaces in outer fan sections; (5) more frequent nontabular amalgamation surfaces in channel fills; and (6) more frequent dish structures in middle fan than outer fan successions. Rarely exposed fan valley fills may be identified by coarse conglomerates. Moreover, in proximity to fan valley fills, relatively mud-rich sediments may be observed that derive from the depositional system of the basin slope.