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Pipe

Distribution by Scientific Domains

Engineering	37%
Chemistry	23%
Polymers and Materials Science	18%
Earth and Environmental Science	7%
Life Sciences	6%
Medical Sciences	3%
6 Other Domains	6%

Distribution within Engineering

Numerical Methods & Algorithms	18%
General & Introductory Civil Engineering & Construction	13%

Kinds of Pipe

Terms modified by Pipe

Selected Abstracts

A pediatric screening instrument to detect problematic infant,parent interactions: Initial reliability and validity in a sample of high- and low-risk infants

INFANT MENTAL HEALTH JOURNAL, Issue 4 2001
Barbara H. Fiese
The purpose of this study was to determine the initial reliability and validity of a screening instrument developed to detect problematic interactions between infants and parents as part of a pediatric well-baby exam. Participants included 117 infant,mother dyads (57 preterms and 60 full terms) assessed when infants were 6 to 9 months old. Mothers and infants were observed playing an interactional game such as peek-a-boo during the course of the pediatric exam. The game was scored for degree of interactional reciprocity using the Pediatric Infant Parent Exam (PIPE). Acceptable levels of interrater reliability were achieved. As predicted, higher risk infants and their mothers exhibited more problematic interactions than lower risk infants and their mothers. Results indicated that the PIPE was a reliable means of screening for interactional difficulties, that was sensitive to, but not synonymous with, neonatal health indices. ©2001 Michigan Association for Infant Mental Health. [source]

Probing Pineal-specific Gene Expression with Transgenic Zebrafish,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008
Daisuke Kojima
The pineal gland of zebrafish (Danio rerio) contains light-sensitive photoreceptor cells and plays an important role in the neuroendocrine system. The zebrafish exorhodopsin gene encodes a pineal-specific photoreceptive protein, whose promoter region harbors a cis -acting element, pineal expression-promoting element (PIPE), directing pineal-specific gene expression. For in vivo genetic studies on PIPE-binding proteins and their regulatory mechanisms, we generated a transgenic zebrafish line, Tg(P20 -rh/P:gfp), that expresses green fluorescent protein (GFP) under the control of the zebrafish rhodopsin promoter fused with 20 PIPE repeats. In Tg(P20 -rh/P:gfp) fish, PIPE-dependent gene expression is visualized by GFP fluorescence in the pineal gland along with PIPE-independent GFP signals in the retinal rod photoreceptors. The transgenic fish exhibit detectable and reproducible GFP fluorescence in the larval pineal gland by 5 days postfertilization. Antisense morpholino-mediated knock-down of a pineal transcription factor gene, otx5, suppresses pineal GFP expression in the transgenic line. In a pilot screen of N -ethyl- N -nitrosourea-treated fish of the GFP transgenic line, we isolated potential dominant mutations that cause attenuation of pineal GFP fluorescence with a marginal effect on the retinal GFP signal. The results suggest that the Tg(P20 -rh/P:gfp) line will be useful for detecting deficits in PIPE-dependent gene expression in the pineal gland. [source]

A New Pentadentate Ligand Forms Both a Di- and a Mononuclear MnII Complex: Electrochemical, Spectroscopic and Superoxide Dismutase Activity Studies

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 28 2007
Federico Cisnetti
Abstract The X-ray crystal structure of the dinuclear complex[1(PF6)2] derived from a new ligand bearing both imidazole and phenolato moieties, namely N -(2-hydroxybenzyl)- N,N,-bis[2-(N -methylimidazolyl)methyl]ethane-1,2-diamine (LH), is described and its properties in organic solvent (CH3CN) investigated (EPR, electrochemistry). [1(PF6)2] is shown to be a mononuclear MnII species in aqueous solution and displays an efficient SOD-like activity, as measured by the McCord,Fridovich assay performed both in conventional phosphate buffer and in a noncoordinating buffer (PIPES). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

LEAD ISOTOPIC EVIDENCE FOR A MIXED PROVENANCE FOR ROMAN WATER PIPES FROM POMPEII,

ARCHAEOMETRY, Issue 1 2000
M. BONI
Lead isotope analysis has been applied to the investigation of some Roman objects found in the town of Pompeii, consisting mostly of fistulae from the Augustan water supply system. The results of the analyses have produced ratios between 18.10 and 18.66 for 206Pb/204Pb, between 15.63 and 15.72 for 207Pb/204Pb and between 38.21 and 38.98 for 208Pb/204Pb. These data point to a fairly complex origin for the lead artefacts, probably involving several successive meltings and recyclings of a rather heterogeneous lead supply. The spread of lead isotope ratios can only be reconciled with a multiplicity of end-members, at least three, but very probably more. There is one certain Sardinian ore, other indistinguishable Hercynian ores of Sardinia and/or Spain, and several different Alpine Mesozoic-Tertiary mineralizations of the Mediterranean basin (Spain, Greece, Tuscany). [source]

Study on heat transfer characteristics of reservoir embedded loop heat pipe (1st report, Influence of evaporator orientation against gravity and charged liquid weight on heat transfer characteristics)

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2007
Hiroaki Ishikawa
Abstract High-powered satellites need larger heat rejection areas. A deployable radiator is one of the key technologies for a high-powered satellite bus. A Reservoir Embedded Loop Heat Pipe (RELHP) is a two-phase heat transfer device that constitutes a deployable radiator. RELHP has an evaporator core which is used as a liquid reservoir to enhance operational reliability. This paper presents the heat transport characteristics of a RELHP under changing evaporator orientation against gravity and charged ammonia weight by experiment and calculation. Liquid slug position in the reservoir has a great influence on heat transport characteristics, caused by changing heat transfer coefficients between returned liquid into the evaporator and vapor in the reservoir. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(3): 143, 157, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20150 [source]

Hydromechanical stimulation of bioluminescent plankton

LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2002
Stefan Blaser
Abstract The response of the bioluminescent dinoflagellate Pyrocystis fusiformis was investigated for different hydraulic conditions (,hydromechanical stimulation'). Pipe flow and oscillating shear produced luminescence, whereas changes in hydrostatic pressure were not stimulating. More intense fluid motion led to higher intensity, mainly due to a higher probability of cell response. The organism was also able to emit light in a glucose,salt mixture. The experiments suggest that the cells are effectively stimulated if the flow conditions change in time. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Reconstruction of MR images from data acquired on an arbitrary k -space trajectory using the same-image weight

MAGNETIC RESONANCE IN MEDICINE, Issue 2 2002
Yongxian Qian
Abstract A sampling density compensation function denoted "same-image (SI) weight" is proposed to reconstruct MR images from the data acquired on an arbitrary k -space trajectory. An equation for the SI weight is established on the SI criterion and an iterative scheme is developed to find the weight. The SI weight is then used to reconstruct images from the data calculated on a random trajectory in a numerical phantom case and from the data acquired on interleaved spirals in an in vivo experiment, respectively. In addition, Pipe and Menon's weight (MRM 1999;41:179,186) is also used in the reconstructions to make a comparison. The images obtained with the SI weight were found to be slightly more accurate than those obtained with Pipe's weight. Magn Reson Med 48:306,311, 2002. © 2002 Wiley-Liss, Inc. [source]

Barium Sulphate Agglomeration in a Pipe , An Experimental Study and CFD Modeling

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2003
J. Ba
Abstract Agglomeration effects, observed during precipitation of barium sulphate in the unpremixed feed two-dimensional tubular precipitator, are studied experimentally and interpreted theoretically. Effects of process parameters on precipitation,agglomeration phenomena are predicted using a CFD based model that describes micromixing (the multiple-time-scale turbulent mixer model is used) and precipitation (including nucleation, growth and agglomeration of crystals). Agglomeration rate is defined as a product of the collision frequency and the probability of agglomeration. [source]

Comparison of Additional Costs for Several Replacement Strategies of Randomly Ageing Reinforced Concrete Pipes

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 7 2009
Franck Schoefs
Some of them carry seawater and can deteriorate with time because of internal corrosion. Because of the low O2 content of aggressive water, slow corrosion is expected for such applications. If the RCPs are not periodically replaced, they will eventually fail. Replacement strategies for these pipes depend on (1) the risks associated with the failure of the water distribution network, and (2) the costs associated with replacing the pipes, including the removal of existing pipes, installation of new pipes, and associated production losses. Because of the lack of statistical data regarding RCP failure, the development of a risk-based replacement strategy is not an easy task. This article demonstrates how predictive models for the evolution of the failure of RCPs and the associated consequences of failure can be used to develop risk-based replacement strategies for RCPs. An application for the replacement strategies of a network modeled as a system consisting of 228 RCPs is presented as a case study. We focus on the assessment of the number of replaced components that governs the costs. The main objective of this article is to provide a theoretical approach for comparing replacement strategies, based on (1) the results of a reliability study, (2) the representation of the distributions of failed components (binomial distribution), and (3) the decision tree representation for replacement of RCPs. A focus on the scatter of the induced costs themselves is suggested to emphasize the financial risk. [source]

Numerical modelling of compensation grouting above shallow tunnels

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 5 2005
C. Wisser
Abstract This paper describes the development of a numerical model for compensation grouting which is a useful technique for the protection of surface structures from the potentially damaging movements arising from tunnel construction. Pipes are inserted into the ground between the tunnel and the overlaying structure from an access shaft. Buildings on the surface are instrumented and movements are carefully monitored. Once the deformations exceed a certain Trigger Level, grout is injected into the ground to prevent damage. In the finite element model described here, compensation grouting is modelled by applying an internal pressure to zero-thickness interface elements embedded in the mesh. An ,observational algorithm' is used, where the deformations of the surface are monitored and used to control the injection process. Example analyses of compensation grouting are given for three-dimensional tunnel construction underneath a greenfield site. Different strategies are used to control the injection process and their effectiveness in preventing surface movement is assessed. The numerical model is shown to replicate general behaviour expected in the field and is capable of modelling the control of ground surface movements at a greenfield site. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Lebensdauerabschätzung an Kunststoffrohren mittels Zeitstand-Innendruckversuch

MATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 5 2007
C. Berger
lifetime prediction; plastic pipes; internal pressure creep test Abstract Die Lebensdauervorhersage an Kunststoffrohren basiert nach dem aktuellen Stand des technischen Regelwerkes hauptsächlich auf dem Zeitstand-Innendruckversuch. In diesem Versuch werden die Rohre bei definiertem Innendruck und erhöhten Temperaturen akzeleriert geprüft, und aufgrund des geltenden Arrheniusgesetzes erfolgt daraufhin eine Lebensdauerextrapolation der Messwerte. Lifetime Prediction of Plastic Pipes by means of Internal Pressure Creep Test The Lifetime Prediction of plastic pipes is based, according to the current set of relevant technical regulations, mainly on the Internal Creep Rupture Test. In this examination, the test for the pipes performed in an accelerated mode with a defined internal pressure and at increased temperatures. In compliance with the applicable Arrhenius rate law, an extrapolation of the measured values then takes place. [source]

Is ,new' anti-Semitism really ,new'?,

PSYCHOTHERAPY AND POLITICS INTERNATIONAL, Issue 2 2006
George Halasz
Abstract The paper considers whether the ,new' anti-Semitism identified by, for example, Bauer, Pipes and Sacks is in fact a new phenomenon. It considers several key moments in the history of anti-Semitism, together with a series of meetings facilitated by Volkan between psychotherapists affected by the Holocaust. The conclusion is that the ,new' manifestations are ,old' processes reactivated in new contexts. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Suspension of Particles from the Bottom of Pipes and Stirred Tanks by Gassed and Ungassed Flows

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2003
Rex B. Thorpe
Abstract Widely accepted correlations and theoretical predictions for hydraulic conveying of solids in pipelines are compared with the literature on the suspension of particles in stirred tanks. Good agreement is found between the correlations and the theoretical predictions both within and between the two fields of study. The effect on the suspension velocity of introducing gas into the pipe and the stirred tank is remarkably similar. In both cases, the shear stress remains broadly unchanged when gas is added. Since the effect of the addition of gas on shear stress is quite well understood in both cases, this is a helpful result. Des corrélations et des prédictions théoriques largement acceptées pour le convoyage hydraulique de solides dans des conduites sont comparées à des données de la littérature scientifique sur la suspension des particules dans des réservoirs agités. Un bon accord est trouvé entre les corrélations et les prédictions théoriques dans et entre les deux champs d'étude. L'effet sur la vitesse de suspension de l'introduction de gaz dans la conduite et le réservoir agité est remarquablement similaire. Dans les deux cas, la contrainte de cisaillement reste largement inchangé lorsqu'il y a ajout de gaz. Ce résultat est utile car l'effet de l'ajout de gaz sur la contrainte de cisaillement est assez bien compris dans les deux cas. [source]

Macrocrystal Garnet and Its Inclusions in Kimberlite Pipes from the Mengyin Area, Shandong Province, China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010
Lijuan WANG
Abstract: Based on previous studies of kimberlite xenoliths and diamond inclusions in this region, macrocrystal garnet was analyzed with the electric microprobe technique (EPMA). The garnet is collected from the Shengli No.1 kimberlite pipe in the Mengyin area of Shandong Province, China. The results indicate that the garnet contains two kinds of multiphase inclusions: one is K-, B-, and Cl-bearing oxygen-free phase, K- and Cl-bearing oxygen-free phase, and volatile-bearing garnet inclusions (in1 and in3); and the other is chlorite, phlogopite, apatite and calcite (in2). It is suggested that the formation of garnet and its inclusions is associated with strongly reduced mantle fluid. Such a fluid was transformed from ultra-deep high-reduction oxygen-free fluid into low-reduction alkaline fluid, and finally into oxidized fluid with low oxygen fugacity. This result confirms that the Mengyin area underwent metamorphism of slightly active deep fluid, and provides evidence for searching diamond by means of indicative minerals. [source]

An Analysis of Pressure Drop and Holdup for Liquid-Liquid Upflow through Vertical Pipes

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2007
A. K. Jana
Abstract The present study has attempted to investigate pressure drop and holdup during simultaneous flow of two liquids through a vertical pipe. The liquids selected were kerosene and water. The measurements were made for phase velocities varying from 0.05,1.2,m/s for both liquids. The pressure drop was measured with a differential pressure transducer while the quick closing valve (QCV) technique was adopted for the measurement of liquid holdup. The measured holdup and pressure drop were analyzed with suitable theoretical models according to the existing flow patterns. The analysis reveals that the homogeneous model is suitable for dispersed bubbly flow whereas bubbly and churn-turbulent flow pattern is better predicted by the drift flux model. On the other hand, the two fluid flow model accurately predicts the pressure drop in core annular flow. [source]

Titelbild: Pipes of refinery ©Digital Version (Chem. Ing.

CHEMIE-INGENIEUR-TECHNIK (CIT), Issue 3 2008
Tech. 3/2008)
No abstract is available for this article. [source]

A Multicriteria Decision Support Methodology for Annual Rehabilitation Programs of Water Networks

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 7 2007
Pascal Le Gauffre
A first set of criteria is formulated for the purpose of comparing and ranking rehabilitation projects. Each proposed criterion is a measure of a particular impact of the condition of a pipe. The ELECTRE TRI method is implemented for defining rehabilitation priorities. Two reference profiles are used to define the limits of three categories associated with three increasing priority levels. With these two reference profiles, applying the ELECTRE TRI method to an asset stock (a set of pipes that are candidates for rehabilitation) means assigning each pipe to one of six possible priority groups. A second set of criteria, based on the concept of efficiency, is proposed for comparing alternative rehabilitation programs (subsets of the asset stock). [source]

An Ultrasonic Profiling Method for the Inspection of Tubular Structures

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2007
Francisco Gomez
These graphs not only show the inner contour of the pipe but also integrate the intensity of the echoes employed to create the profile. The enhanced profile is generated by superimposing the peak intensity from the returning echoes at the calculated x, y, and z coordinates where it reflected from the pipe wall. The proposed method is capable of showing anomalous conditions, inside pipes filled with liquid, with dimensions smaller than the theoretical lateral and axial resolution of the transducer, in contrast to traditional methods where these kinds of defects are not disclosed. The proposed inspection method and its capabilities were validated through the realization of simulations and experiments. The presented approach was particularly developed with the aim of scanning internal sections of pipes filled with liquid using rotary ultrasonic sonars, but it is expected that this research could be expanded to the inspection of other submerged structures, such as water tanks, or pressurized vessels. [source]

Assessment of Protection Systems for Buried Steel Pipelines Endangered by Rockfall

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2005
Bernhard Pichler
First, a gravel-based protection system (GBPS) is investigated, that is, a pipeline buried in sandy gravel is considered. To assess the load-carrying behavior of this structure when subjected to rockfall, a finite element (FE) model has been developed. The development and the validation of this structural model are strictly separated, that is, they are based on two physically and statistically independent sets of experiments. Subsequently, scenarios of rockfall onto a gravel-buried steel pipe are analyzed considering different boundary conditions and structural dimensions. Following the conclusions drawn from these numerical analyses, an enhanced protection system (EPS) is proposed. It consists of gravel as an energy-absorbing and impact-damping system and a buried steel plate resting on walls made of concrete representing a load-carrying structural component. The potential and the limitations of both protection systems are discussed in detail. [source]

Stress-life fatigue assessment of pipelines with plain dents

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 12 2009
S. B. CUNHA
ABSTRACT This paper presents a new algorithm for assessing the fatigue life of dented pipelines. The proposed methodology was conceived according to the current stress-life fatigue theory and design practice: it employs S,N curves inferred from tensile test material properties and uses well established methodologies to deal with the stress concentration, the mean stress and the multi-axial stress state that characterizes a dented pipe. Finite element analyses are carried out to model the denting process and to determine the stress concentration factors of several pipe-dent geometries. Using dimensional analysis over the numerical results, a non-dimensional number to characterize the pipe-dent geometry is determined and linear interpolation expressions for the stress concentration factors of dented pipelines are developed. Fatigue tests are conducted with the application of cyclic internal pressure on small-scale dented steel pipe models. In view of the fatigue test results, the more appropriate S,N curve and mean stress criteria are selected. [source]

A fatigue and creep study in austenitic stainless steel 316L used in exhaust pipes of naval gas turbines

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9 2004
R. F. MARTINS
ABSTRACT Exhaust pipes of naval gas turbines are made of thin wall tubing of stainless steel grade AISI 316L. The tubes are fabricated by butt welding of different sections with longitudinal and circumferential joints. The plate thickness is about 4.0 mm, and the working temperature varies between 600 °C and 400 °C in the critical zones of the pipe, in the lower and central areas, respectively. The loadings in the tube induce high-temperature fatigue and creep-fatigue cracks have nucleated and propagated in the tube near some welded joints. The paper presents FCGR data obtained in CT specimens of used material taken from the pipes and tested at RT, 335, 500 and 600 °C. Preliminary creep data obtained in tension, in thin-sheet specimens (about 4 mm thickness), also taken from the conduct wall and tested at 500, 550 and 600 °C are also given. These results are crucial to perform a fatigue-creep interaction life assessment of the critical parts of the structure in the near future. Finally, the paper presents results of research work to investigate carbide precipitation and formation in virgin thin-sheet specimens subjected to several types of thermal exposures. In some cases, 3,4 d was the time interval between exposures. Grain size measurements were carried out together with microstructural observations in the SEM. The influence of time, temperature and time interval between thermal exposures was assessed comparing the microstructures. [source]

Fatigue of cantilevered pipe fittings subjected to vibration

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 8 2003
M. HAMBLIN
ABSTRACT Vibration fatigue failures in piping systems often occur at cantilevered small-bore fittings (SBF) such as pressure tappings and drain valves. Piping vibration has often been assessed by measuring vibration displacement or velocity. However, in the case of straight cantilevered fittings with a concentrated mass, a better method exists. This paper presents a simple robust method of calculating vibration induced stress for cantilevered fittings at both the fitting branch neck and the main pipe. The method is based on measurement of acceleration at the concentrated mass (e.g., valve) and simple mechanics calculations. Extensive laboratory and field verification of the technique is presented. The choices of a fatigue strength criterion, such as ASME BPVC VIII Div. 2, BS7608, or a fracture mechanics approach such as BSI PD6493, are discussed. Several case studies are presented as well as simple ,good engineering practice' rules-of-thumb for SBF design. These ,rules-of-thumb' are now incorporated in the piping specifications of the author's company. [source]

Assessment of fire protection performance of water mist applied in exhaust ducts for semiconductor fabrication process

FIRE AND MATERIALS, Issue 5 2005
Yi-Liang Shu
Abstract Fume exhaust pipes used in semiconductor facilities underwent a series of fire tests to evaluate the performance of a water mist system. The parameters considered were the amount of water that the mist nozzles used, the air flow velocity, the fire intensity and the water mist system operating pressure. In order to make a performance comparison, tests were also performed with a standard sprinkler system. The base case served as a reference and applied a single water mist nozzle (100 bar operating pressure, 7.3 l/min water volume flux and 200 µm mean droplet size) installed in the pipe (60 cm in diameter) subjected to a 350°C air flow with an average velocity of 2 m/s. In such a case, the temperature in the hot flow dropped sharply as the water mist nozzle was activated and reached a 60°C saturation point. Under the same operating conditions, four mist nozzles were applied, and made no further contribution to reducing the fire temperature compared with the case using only a single nozzle. Similar fire protection performances to that in the base case were still retained when the exhaust flow velocity increased to 3 m/s and the inlet air temperature was increased to 500°C due to a stronger input fire scenario, respectively. Changing to a water mist system produced a better performance than a standard sprinkler. With regard to the effect of operating pressure of water mist system, a higher operating pressure can have a better performance. The results above indicate that the droplet size in a water-related fire protection system plays a critical role. Copyright © 2005 John Wiley & Sons, Ltd. [source]

A simple method for measuring tiller volume of grasses

GRASS & FORAGE SCIENCE, Issue 4 2004
A. F. Sbrissia
Abstract A simple method for measuring tiller volume of grasses is described. The equipment, based on the communicant pipe principle, was built using a PVC pipe linked to a laboratory volumetric pipette. The results showed a high degree of consistency and were similar to empirical results published in the literature, indicating that tiller volume of grasses can be easily measured with this technique. [source]

A Simple Correction for Slug Tests in Small-Diameter Wells

GROUND WATER, Issue 3 2002
James J. Butler Jr.
A simple procedure is presented for correcting hydraulic conductivity (K) estimates obtained from slug tests performed in small-diameter installations screened in highly permeable aquifers. Previously reported discrepancies between results from slug tests in small-diameter installations and those from tests in nearby larger-diameter wells are primarily a product of frictional losses within the small-diameter pipe. These frictional losses are readily incorporated into existing models for slug tests in high-K aquifers, which then serve as the basis of a straightforward procedure for correcting previously obtained K estimates. A demonstration of the proposed procedure using data from a series of slug tests performed in a controlled field setting confirms the validity of the approach. The results of this demonstration also reveal the detailed view of spatial variations in K that can be obtained using slug tests in small-diameter installations. [source]

A Case Study of Soil-Gas Sampling in Silt and Clay-Rich (Low-Permeability) Soils

GROUND WATER MONITORING & REMEDIATION, Issue 1 2009
Todd A. McAlary
Soil-gas sampling and analysis is a common tool used in vapor intrusion assessments; however, sample collection becomes more difficult in fine-grained, low-permeability soils because of limitations on the flow rate that can be sustained during purging and sampling. This affects the time required to extract sufficient volume to satisfy purging and sampling requirements. The soil-gas probe tubing or pipe and sandpack around the probe screen should generally be purged prior to sampling. After purging, additional soil gas must be extracted for chemical analysis, which may include field screening, laboratory analysis, occasional duplicate samples, or analysis for more than one analytical method (e.g., volatile organic compounds and semivolatile organic compounds). At present, most regulatory guidance documents do not distinguish between soil-gas sampling methods that are appropriate for high- or low-permeability soils. This paper discusses permeability influences on soil-gas sample collection and reports data from a case study involving soil-gas sampling from silt and clay-rich soils with moderate to extremely low gas permeability to identify a sampling approach that yields reproducible samples with data quality appropriate for vapor intrusion investigations for a wide range of gas-permeability conditions. [source]

Study on heat transfer characteristics of porous metallic heat sink with conductive pipe under bypass effect

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2009
Sheng-Chung Tzeng
Abstract The work investigated the forced convection heat transfer of the heat sink situated in a rectangular channel by considering the bypass effect. The fluid medium was air. The relevant parameters were the Reynolds number (Re), the relative top by-pass gap (C/H), and the relative side by-pass gap (S/L). The size of the heat sink was 60 mm (L)×60 mm(W)×24 mm(H). Two heat sinks were employed as test specimens: (A) the 0.9-porosity aluminum foam heat sink and (B) the 0.9-porosity aluminum foam heat sink with a 20 mm diameter copper cylinder. The copper cylinder was used as a conductive pipe of heat sink. The average Nusselt number was examined under various forced convection conditions. Experimental results demonstrate that increasing by-pass space decreased the Nusselt number. Besides, the average Nusselt number of mode B heat sink was higher than that of mode A heat sink by 30% for the case without by-pass flow. The heat transfer enhancement by the copper cylinder would decline as the by-pass space grew. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20247 [source]

Analysis of flow and heat transfer in evaporator porous wicking structure of a flat heat pipe

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 2 2009
Congxiang Hu
Abstract With a specified pressure distribution, an analytical investigation was conducted to explore the flow and heat transfer characteristics in an evaporator porous wicking structure of a flat heat pipe. The boundary effect on the flow rate is more significant than the inertia, and both the boundary and inertia effects exert very little influence on fluid layer thickness and velocity distribution. The bottom of the porous layer is at a quite uniform temperature, and the heat flux is almost normal to the solid boundary. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20237 [source]

Shape of isolated bubble in intermittent flows in a horizontal pipe

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2007
Gu Hanyang
Abstract An experimental study on the shape of a single bubble similar to those observed in a horizontal plug/slug flow was performed using visual observation and conductance probes. The results indicated that the shapes of the bubble nose and the bubble body depend on the Froude number defined by gas/liquid mixture velocity, whereas the shape of the back region of the bubble depends on both the Froude number and bubble length. The photographic images showed that the structural feature of the bubble head is related to the motion characteristics of the bubble. The transition from plug flow to slug flow occurs when the tail of the bubble changes from a staircase to hydraulic jump pattern with the increasing of the Froude number and bubble length. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(5): 276, 285, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20161 [source]

Study on heat transfer characteristics of reservoir embedded loop heat pipe (1st report, Influence of evaporator orientation against gravity and charged liquid weight on heat transfer characteristics)