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Considering the assembly and application in electric vehicles, battery thermal management systems (BTMSs) with phase-change materials (PCMs) are restricted by fluid leakage, high rigidity, and low ...

Uneven surface emissivity will cause illusory temperature variation in infrared surface temperature mapping. For this reason, most of the detailed reviews on the use of infrared thermography (IRT) for leakage detection have mainly focused on surfaces with homogeneous emissivity or the recognition of negative temperature gradients, while reports on sensing hot fluid leakage for uneven surface emissivity are very rare. In this study, a hypothesis is put forward and a new leakage detection method is proposed that uses a transient heating-cooling-heating process in association with a subtraction method of infrared images to eliminate the disturbance of inhomogeneous valve surface emissivities. A theoretical analysis is established that is experimentally tested as a case study. The results shows that the hypothesis is clear and the effect of the uneven emissivity is suppressed for the recognition of positive temperature gradients (hot fluid leakage) on a metal valve sample. The current work provides new insights on the modification of the surface emissivity under certain conditions, which has been a major limitation of passive IRT in the past.

Elastomeric seals are devices that are widely used to prevent fluid leakage through the interface of a variety of mating industrial components. Gas leak through these seals involves gas flow through the interface of the seal and its corresponding mating component. This flow is understood to initiate due to separation of the surfaces at the sealing interface due to gas pressure. Modelling this separation can aid in optimizing seal designs and in estimating seal failure. In this paper, we develop a simple wedge penetration-based model to describe the separation. The frame work of the model is generic so that it can represent gradual as well as complete seal failures. We illustrate the applicability of this model for elastomer–metal interfaces which involve gradual separation. Nitrogen gas leak rate experimental data for stainless steel with three different elastomers are described using the model. We further discuss the processes and challenges involved in employing this model to estimate leak rate of gas through elastomeric seals of different geometries.

Introduction During routine surgery, rapid hemostasis, especially the rapid hemostasis of internal organs, is very important. The emergence of in-situ electrospinning technology has fundamentally solved this problem. It exhibits a high speed of hemostasis, and no bleeding occurs after surgery. Thus, it is of great significance. The use of sutures in some human organs, such as the intestines and bladder, is inadequate because fluid leakage occurs due to the presence of pinholes. Methods Three types of large intestine wounds with an opening of about 1 cm were investigated. They were untreated, treated by needle and threaded, and treated by hand-held electrospinning, respectively. Results The results show that hand-held electrospinning technique effectively prevented the exudation of fluids in the intestinal tract. The average diameter of the nanofibrous membrane was about 0.5 μm with hole of several micrometers. It can be elongated 90% without breakage. The hand-held electrospinning device could be used with nitrile gloves, preventing the risk of infection caused by exposed hands. Discussion This work can provide a reference for future animal experiments and clinical experiments. However, safety should be investigated before application.

Magnetorheological (MR) dampers are common methods that are used to mitigate cable vibrations with high effectiveness. Under the long-term effect of external loads and harsh environment, M...

Metallic seals are crucial machine elements in many important applications, e.g., in ultrahigh vacuum systems. Due to the high elastic modulus of metals, and the surface roughness which exists on all solid surfaces, if no plastic deformation would occur one expects in most cases large fluid flow channels between the contacting metallic bodies, and large fluid leakage. However, in most applications plastic deformation occurs, at least at the asperity level, which allows the surfaces to approach each other to such an extent that fluid leakage often can be neglected. In this study, we present an experimental set-up for studying the fluid leakage in metallic seals. We study the water leakage between a steel sphere and a steel body (seat) with a conical surface. The experimental results are found to be in good quantitative agreement with a (fitting-parameter-free) theoretical model. The theory predicts that the plastic deformations reduce the leak-rate by a factor $\approx 8$, 10 pages, 10 figures

The transient elliptical contacts in boundary lubrication widely exist in modern mechanical systems with high durability. However, little attention has been paid to the squeeze effect of fluid film in this condition. A deterministic model which combines the contact mechanics with the pure squeeze lubrication model has been developed with the aim of understanding the squeeze effect of fluid film under the transient boundary lubrication. The leakage coefficient was introduced to capture the fluid leakage of rough surfaces. The squeeze effect of trapped fluid film was confirmed through comparing the fluid film stiffness in boundary lubrication with that of the elastohydrodynamic lubrication. Additionally, the effects of fluid film entrapment/leakage on the boundary lubrication performance were numerically analyzed during transients. The load capacity of the squeeze films is built up due to the trapped fluid film in the micro-valleys, which can be significantly affected by the interfacial shear coefficient of the boundary films. The simulation results show a good agreement with the experiments and justify the present numerical model is feasible in the boundary lubrication regime.

The tube hydroforming process uses a pressurized fluid as the forming medium, and the sealing efficiency of the internal fluid has an important influence on the hydroformability. This study investigates the applicability of segmented rubber rings to prevent pressure leakage in hydroforming. When the target shape is non-axisymmetric, the possibility of pressure leakage is increased due to the biased stress distribution on the punch. A sealing system is proposed, which is composed of segmented rubber rings, a cylindrical sleeve, and a punch with an end fillet. When the rubber rings are compressed, the reaction force acting on the rings contributes to the prevention of pressure leakage. The circumference of the tube end becomes more tightly sealed by the axial pressure between the punch and sleeve. A deformation analysis was conducted using a compression test, which revealed that the combined use of a steel ring with a rubber ring was more efficient in preventing fluid leakage. The enhanced sealing effect of the proposed system with rubber and steel rings was confirmed by comparing the experimental results with a conventional hydroforming process.

The influence of configuration of regular microrelief on leakage of fluid pumped through plunger pair of sucker-rod pump is studied. An experimental unit developed to study fluid leakage through plunger pair is presented. The experimental data and the results of simulation in ANSYS CFX of leakage through plunger pairs with and without microrelief are given. Practical recommendations are offered on the choice of geometric parameters of plunger pair grooves for minimizing leakage.

The paper addresses the friction process in coaxial sealing systems of hydraulic cylinders based on studies starting from an analysis of the energy efficiency ensured by these actuators. Notwithstanding the main purpose of a sealing system, namely to prevent fluid leakage, energy related aspects should also be considered, materialised in the efficiency of the hydraulic cylinders. The efficiency of hydraulic cylinders depends on the magnitude of the friction forces caused by the sealing systems. In this respect the paper focuses on discussing studies concerning the types of friction in the sealing tribosystem and on establishing methodologies for the analytical and experimental determination of the friction forces introduced by coaxial sealing systems. The obtained results yield the conclusion that coaxial sealing systems generate friction forces several times smaller than those caused by other sealing types, thus ensuring a higher efficiency to hydraulic cylinders equipped with such sealing elements.

International audience; Mechanical face seals are used to avoid fluid leakage from pressurized zones to the environment in many rotating machineries. The initial research into the lubrication mechanism of these components was initiated several decades ago and numerous studies, both theoretical and experimental, have been carried out on the subject. Surface texturing has been of growing interest in recent years, but only a few studies have been devoted to textured mechanical face seals. Thus, the aim of the present work is to provide experimental, as well as theoretical, results with a comparison of smooth and textured seals. The temperatures of the seals are measured by means of infrared thermography. A 50% reduction in friction for the whole speed range and a reduction in the temperature rise of the sealing interface, attaining 40% at the highest speed values, are reported. Because it is not possible to measure the film thickness experimentally, a numerical thermoelastohydrodynamic model is used, taking into account the seal face deformations. A comparison between the experimental and theoretical temperatures allows the model to be validated. It is shown that, as expected, the film thickness increases with speed as a result of the pressure generated in the dimples. However, after a threshold, it starts to decrease because of the detrimental effect of thermal deformation. These results show that fluid solid coupling must be considered when designing the surface texture for a mechanical seal.

The new screw-propelled 3D printer can realize 3D printing with granular plastic materials. The granular plastic material cost low and need not pay more attention on material flexibility. In this paper, the motion characteristics of bubbles produced in the printing processing of the screw-propelled 3D printer are studied. Through the analysis of the screw structure, and establish the corresponding three-dimensional model, the flow field of screw propulsion system is established by using FLUENT software. Through the simulation, the effects of the speed of the screw propeller, inlet pressure and screw pitch on the velocity of the bubble rise is studied. And the different locations of the bubble are concerned. In order to make the bubble escape from the fluid, a new structure of screw propeller is improved. The simulation result shows this improved structure can get a good performance to help to remove the bubbles in molt plastic material. And the fluid leakage can be compensated by increase the speed of the screw propeller.

Magnetic brakes are the popular means to provide efficient damping to the motion of manipulators to avoid any damages. Commercially available magnetic brakes are either single degree of freedom electro-magnetic brakes or spherical brakes being operated by permanent magnet. Fully controlled braking in multi-DOF has only been explored using MR fluid but the risk of fluid leakage limits its application in human sensitive operations. This paper proposes a new design of a spherical electro-magnetic brake (SEMB) system that utilizes the solid friction surfaces to provide controlled braking torque in 3 DOF. The mathematical model of the SEMB has been derived. The design of SEMB is then optimized for maximizing the magnetic forces. The experimental results are compared with FEM simulation results and analytical model.

Light water reactors in Japan are expected to restart sequentially after given permission in condition to meet the new regulatory requirements. Since several safety related systems were added to the plants through the process of the new regulatory requirements, the numbers of components to be inspected, which is already a large amount, will increase even more after the restart in Japan. Effective measure will be required to command maintenance activities by reasonably assigning limited resource. The authors have planned a research project aiming optimization of maintenance considering influence of fluid leakage behavior with pipe failure, mainly targeting less-safety related piping and components. The experimental facility which has the ability to evaluate the fluid leakage behavior with pipe failure was constructed. By using this facility, it is able to conduct the test of the water jet, the flashing and the steam flow leaked from various flaw geometries of the piping.

Tissue sealants can improve control over bleeding and other undesirable bodily fluid leakage by adhering to the tissue surface and providing a liquid-proof barrier. The overall aim of our research program is to lay the basis for the development of a new family of bioinspired sealants based on alginate and phenolic compounds. Combining different burst pressure measurement formulations with assessment of Young modulus and gel point measurements allows us additional insight into the role played by different phenolic molecules and their contribution to the sealant's performance. We found that although the presence of the phenols altered the sealant's gel point, their contribution is manifested in the sealant–substrate interaction rather than in cohesion or viscosity. Evidence of the importance of phenol structure is presented.

The authors analyze numerically propagation of hydraulic fractures from a circular hole boundary under viscous fluid injection in plane strain condition, considering influence of the fluid viscosity and elastic characteristics. The approximate solution is compared with the recent numerical calculations of exact formulated problem. Effect of configuration of incipient hydraulic fractures on development of the overall hydrofracturing pattern is analyzed, and stable growth conditions for several long fractures are found.

Three dimensional solid-fluid interaction numerical analysis models of both the finger seal with herringbone-grooved pad and the finger seal with herringbone-grooved rotor were established in order to study the performance of hydrodynamic finger seal. The models investigated fluid radial under pad force and fluid leakage as a function of both the rotor speed and the high- to low-pressure differential. It was shown that the finger seal with herringbone-grooved structure in pad or in rotor could bring lift force under the finger pad so as to keep the finger seal in non-contacting status. For the two types of finger seal, their load carrying ability and fluid leakage varying with the pressure differential were almost same. In the same velocity of rotor surface, the load carrying capacity of the finger seal with herringbone- grooved rotor was greater and the leakage was less than that of the finger seal with herringbone-grooved pad respectively. With the conditions of rotor structure allowing, it is suggested to select the finger seal with herringbone-grooved rotor first for designing the hydrodynamic finger seal with herringbone-grooved structure.

Elastomeric seals are devices that are widely used to prevent fluid leakage through the interface of mating parts. In this paper, we study the leak characteristics of a representative elastomeric s...

In order to prevent the occurrence of cementing fluid leakage in low leakiness formation and protecting reservoir effectively, low density cement system is widely used. As the use of lightening admixture to reduce the density in low density cement system, the cement acoustic impedance of low density cement system is different from conventional density, it can not reflect the real cementing quality when using the criteria of conventional density cement cementing quality evaluation to evaluate the cement job quality of low density cement. Targeted at this problem, this paper conducted a method to improve the criteria of evaluation of cementing for low density cement. Studies have shown that the compressive strength and the acoustic impedance has a good linear relationship in different types of low density cement conserved 24 h and 48 h, so we put forward a method to improve the evaluation of cementing quality of low density cement based on the compressive strength of low density cement.

Fundamental experiments on fluid leakage from tapered seals due to sleeve rotation were carried out. The apparatus was designed so that the surface tension, which generates a sealing function, acts effectively in terms of size and accuracy similar to its behavior in an actual device. The shapes of the interface (boundary surface of two kinds of fluids) at several rotational speeds were measured with an ultra-focus laser microscope, and the features of fluid leakage were observed with a high-speed camera. The experimental results of the positions of the bottoms of the interface coincided comparatively well with the theoretical ones. We also verified that the threshold speeds in the experiment on fluid leakage could broadly be estimated by using the theoretical ‘ultimate’ and ‘triggering’ critical rotational speeds of the sleeve.

In vitro shock wave lithotripsy (SWL) research is typically performed utilizing wet coupling lithotriptors with a mesh basket model. This model does not take into account shock wave energy attenuation through tissue. Models using dry coupling lithotriptors rely on immersion chambers and face similar limitations. Ordnance gelatin (OG) displays strength and viscous properties similar to human tissue and is therefore widely used for ballistic tissue injury research. We present our initial experience using an OG tissue simulating scaffold for dry coupling SWL research. Using 10% OG prepared in a disc-shaped mold (five stone wells/gel), we tested the model using a Modulith SLX-F2 lithotriptor and artificial stone phantoms. Following a test of concept run on an empty gel mold and a material integrity check for leakage, we shocked 60 stones (30 narrow focus [NF], 30 wide focus [WF]) in human pooled urine. Half were shocked using gels containing open-ended wells with the remainder closed-ended wells. Fragmentation coefficients (FC) were calculated across both foci and gel models. All gels successfully completed 5,000 shocks (1,000/well) without loss of gel integrity or fluid leakage. The mean FC using open-ended wells was 77.9 ± 7.6% NF and 74.4 ± 4.8% WF, and for closed wells 75.9 ± 8.0% NF and 67.1 ± 3.5% WF. The total model cost including the preparation of gels and begostones was assessed at approximately $1 per stone (Canadian). Ordnance gel serves as an excellent surrogate tissue shockwave scaffold providing an easily manufactured, reproducible and inexpensive model for dry coupling SWL research.

The detection of acoustic emission (AE) signals produced by liquid and gas leakage through valves can be related directly to the qualitative leakage rate. This allows for cost estimation of losses in processes for several industries. However, to find out the relationship between qualitative leakage rate and AE signal large amounts of experimental data is needed. This paper presents a theoretical investigation of the acoustic emission to detect the internal leakage rate through a valve and experimental validation. The AE signals generated by internal liquid and gas leakage through valves were characterised. The effect of the influenced factors of leakage rates, inlet pressure levels, valve sizes and valve types, on AE parameter, AE RMS , were studied and explained. The results of theoretical and experimental showed that AE signal power computed from the power spectral density (PSD) correlated well with influenced factors of leakage rates. Finally, a novel and inexpensive AE instrument has been invented for predicting qualitative leakage rate using a micro processor and derived relationship.

Seals are extremely useful devices to prevent fluid leakage. We present an effective-medium theory of the leak rate of rubber seals, which is based on a recently developed contact mechanics theory. We compare the theory with experimental results for seals consisting of silicon rubber in contact with sandpaper and sand-blasted PMMA surfaces.

Introduction Parylene coating was added to the silicone layers of the American Medical Systems (AMS) 700 controlled expansion (CX) penile prosthesis cylinders in January 2001. The coating was placed on non-tissue contacting silicone surfaces to increase lubricity, reduce friction, and silicone wear Aim We compared mechanical reliability of the original and Parylene-enhanced AMS 700 CX in a large single surgical group series Methods Seven hundred seventy-five consecutive patients receiving the AMS 700CX prosthesis (596 first time [virgin] and 179 revisions) were followed for 3 years. Four hundred fourteen received the non-coated model and 361 received the Parylene-coated device. Revision-free survival was estimated using the Kaplan–Meier product limit method and compared using the log-rank test. Main Outcome Measures We calculated overall survival from revision for any reason and survival from mechanical problems such as fluid leakage, cylinder, connector or tubing breakage, pump or reservoir defects. Results For the entire series (virgin + revised) the 3-year revision free survival for any cause improved from 78.6% for non-coated to 87.4% for the Parylene-coated implants. Freedom from mechanical breakage showed similar improvement from 89.2% for the non-coated to 97.5% for enhanced models. Conclusion This study documents that short-term mechanical reliability and survival from revision for any cause is significantly increased with Parylene-coated AMS 700CX cylinders compared with the earlier AMS 700CX model with non-coated cylinders. Salem EA, Wilson SK, Neeb A, Delk JR, and Cleves MA. Mechanical reliability of AMS 700 CX improved by Parylene coating. J Sex Med 2009;6:2615–2620.

Fluid leakage out of mechanical equipment such as gearboxes, hydraulic systems, or fuel tanks could cause serious problems and thus should be avoided. Seals are extremely useful devices for preventing such fluid leakages. We have developed a theoretical approach for calculation of the leak rate of stationary rubber seals and the friction force for dynamic seals. The theory is based on a recently developed theory of contact mechanics, which we briefly review. To test the theory, we have performed both simple model experiments and experiments on engineering seal systems. We have found good agreement between the calculated and measured results, and hence our theory has the potential to improve the future design of efficient seals.

The mechanism of fluid leakage trough the free volume between rough surfaces in contact is relevant in physics and in many engineering applications. In the present study, the normal contact problem between randomly generated fractal rough surfaces is solved using the boundary element method. Then, an algorithm for the evaluation of the network involved in the percolation of fluid is proposed. Numerical results are synthetically collected in diagrams relating the free volume involved in the percolation to the dimensionless statistical parameters of the rough surface

It is shown that when sucker-rod pumps are used, fluid leakage in seals of plunger-cylinder and valve pair through hole and radial slot is proportional to the area of the flow section and is also dependent on the shape of the latter. A new type of mechanical seal has been developed that reduces leakage significantly and increases efficiency and nonfailure operating life of piston or plunger pumps.

The authors have established strict formulation of mathematical equations for permeability determination by transient pulse method and extended the formulation to the specified cases, i. e., the authors have applied the transient pulse method to the hollow cylinder specimen and extended it's application to the case where fluid leakage from the pressure cell is taken into account. In the hollow cylinder specimen, fluid leakage along specimen boundary can be easily prevented.Intrinsic permeability k was given by the following formula:k=ακμ log(R0 / Ri) / 2πL V1 V2 / V1 + V2where α is the value to be determined from test data, κ is fluid compressibility, μ is fluid viscosity, R0, Ri and L are the outer radius, the inner radius and the height of the hollow cylinder specimen, respectively. V1 and V2 are capacity of the spaces communicating with the inside and the outside of the hollow cylinder specimen in the pressure cell.The authors developed a simple apparatus for permeability measurement. Pneumatic permeability tests using the apparatus were carried out and the permeability of a specimen made of limestone was determined. The permeability test takes only a few hours even for a specimen made of low-permeability rock because of low viscosity of air.

Preserved pericardium in contact with blood is not thrombogenic, therefore avoiding the use of anticoagulants, and has excellent mechanical properties. Our objective is to take advantage of these characteristics and build a pulsatile ventricular assist device (VAD) with pericardium used as the inner lining of the blood chamber. A mold is used for the tanning of the pericardium, rendering it with an exact shape. A flexible polymeric structure is designed to serve as a base for the pericardium, guiding it and limiting its rate of strain. It consists of two halves, which when outfitted with the interior pericardium lining and connected to each other, form the blood chamber. This assembly is housed in rigid polyvinyl chloride (PVC) shells making up the air chamber for the pneumatic activation. Valves are likewise made of pericardium. Sealing of the chambers was tested statically up to 300 mm Hg with no air or fluid leakage. The device was tested for 60 continuous days in a mock loop, demonstrating hydrodynamic performance adequate for ventricular assist. Micrographs (confocal laser and scanning electron microscopy) were obtained of several pericardium areas, especially on the flexing regions that are a transition between the wet and dry regions. No sign of damage to the pericardium was observed either with the naked eye or at the microscopic level. From the hydraulic performance and materials viewpoints, a completely pericardium-lined pulsatile VAD displaying a polymeric structure that avoids unpredictable bending and limits strain is feasible. The results warrant further studies regarding biocompatibility and strength advantages.

The effect of fluid leakage into insulation material is considered, where the combustible fluid spread over the inner fibres of the material is both slowly oxidizing and undergoing evaporation/desorption. It is found, in particular, that the constant supply of fuel can lead to unexpected oscillatory behaviour in regions of parameter space which would otherwise have been considered safe. In particular, the case of an extremely slow rate of supply of fluid can be the most deceptive in terms of the possibility of ignition. *An early version of this paper was presented at the 16th ICDERS, Cracow, Poland, 4–8 August 1997.

This chapter deals initially with the underlying principles of adhesion and adhesives and the understanding of interfacial behaviour. This provides a basis upon which to understand biological interactions (. Chapter 12). The two broad types of adhesive materials encountered in wound healing are pressure-sensitive adhesives (PSA) and tissue sealants. The function of pressure-sensitive adhesives is to form an adhesive bond between tissue and biomaterial under the influence of pressure. Tissue sealants are liquids that convert to solid form at the tissue surface and in so doing form either an effective seal against fluid leakage or a bond between adjacent tissue surfaces. The different requirements and characteristics of these systems are discussed. © 2011 Woodhead Publishing Limited All rights reserved.

Depending on the throttling process of finger pad gap and the kinetic energy dissipation within the finger gap, finger seal can reduce the fluid leakage. But the deformation of the finger will increase the finger pad gap, which results in the increasing of overall leakage. To evaluate the performances of the finger seal, we used a two-way fluid-structure interaction method to analyse the seal deformation and flow field through the finger seal simultaneously. The numerical analyses show that a strengthened finger seal or a convergent type pad can be considered to reduce the leakage flow through finger pad gap. Finger pad deformation depends mainly on the pressure difference, but not the finger pad gap. There is a strong vortex in the finger gap, which blocks the fluid leakage. The leakage fluid is divided into many small vortices, the kinetic energy of the leakage fluid is dissipated in such a process and its pressure is decreased. When the finger pad deformed, its high pressure end moves toward the shaft, if the pressure difference increases or the shaft oscillated, this end could touch the shaft surface. The position of the maximum radial movement of finger pad does not coincide with the position of the maximum deformation of finger pad, which means the finger pad will be twisted to some extent rather than simply lift.Copyright © 2010 by ASME

Aim To investigate the sealing quality of ProRoot Endo Sealer, a calcium silicate-based sealer and its morphologic characteristics after immersion in a phosphate-containing fluid (PCF). Methodology Single-rooted canals were filled with gutta-percha and either ProRoot Endo Sealer or two commercially available zinc oxide eugenol (ZOE)-based and epoxy resin-based sealers. The sealers were allowed to set for 6 days and the filled teeth were immersed in PCF for 24 h before fluid leakage evaluation. After initial leakage evaluation at the 7th day, each filled root was restored and reimmersed in PCF for 28 days before the second phase of leakage evaluation at 35 days. Cryofractured specimens of additional teeth filled with the three sealers were examined using scanning electron microscopy after immersion in PCF for the two periods. Results One-way repeated measures anova and Tukey test revealed significant differences between the ZOE-based sealer at 35 days and the calcium silicate-based sealer at 35 days (P

Seals are extremely useful devices to prevent fluid leakage. We present experimental results for the leak-rate of rubber seals, and compare the results to a novel theory, which is based on percolation theory and a recently developed contact mechanics theory. We find good agreement between theory and experiment., Comment: 6 pages, 10 figures

Objective The aim of this study was to investigate the apical sealing ability of a newly introduced root canal sealer: iRoot SP Root Canal Sealer. Study design Sixty-eight extracted human anterior single-root teeth were used. The coronal part of each tooth was removed and the root canals were prepared with ProTaper files. The specimens were divided into 3 groups of 20 teeth each. Group A specimens were filled with iRoot SP using the continuous wave condensation technique; Group B specimens were obturated with iRoot SP using a single cone technique; Group C specimens were filled with AH plus by means of the continuous wave condensation technique. Evaluation of the apical leakage was performed with a fluid filtration method at 24 hours and 1, 4, and 8 weeks. Scanning electron microscopy (SEM) was used to qualitatively assess what mechanisms might be responsible for leakage of the different groups. Results There was no significant difference in fluid leakage among the groups, as well as no time effect on leakage (P > .05). SEM revealed both gap-free regions and gap-containing regions in canals filled with both materials. Conclusion iRoot SP was equivalent to AH Plus sealer in apical sealing ability.

Pervious concrete is used as the material for drainage structure in roads, buildings, and water facilities due to its excellent permeability. Existing devices for testing the permeability of pervious concrete do not consider the fluid leakage through the specimen-container interface induced by the large numbers of open pores on the surface of molded specimen. This may significantly affect the precision of the results. In this study, a new permeability test device for pervious concrete was developed and a modified permeability testing method is described. The modified method and currently used test methods were employed to measure the permeability of molded specimens with different porosities, graded aggregates, and admixtures. In order to calibrate the modified method, the permeabilites of the cored specimens were measured using the method and currently used test methods. The comparisons show that the permeabilities of the molded specimens measured using the modified method are lower than the two existing methods, and are approximate to the results of cored specimens. This indicates that for the molded specimens, the modified method can give better precision and more accuracy than the two existing methods.

We investigated the use of thermally treated polydimethylsiloxane (PDMS) for chemically-resistant microchannels. When the PDMS underwent the thermal treatment at 300 °C, swelling was reduced and the surface of the PDMS microfluidic channel endured well in the extracting media such as dichloromethane. Furthermore, despite the small decrease in size after thermal treatment, both the channel shape and transparency were maintained without showing fluid leakage. The thermally treated PDMS had more hydrophilic properties compared to the untreated PDMS. A single step post-casting process described in this work does not require complex chemical treatments or introduction of foreign materials to the host PDMS substrate, thus expanding the application area of PDMS-based microfluidics.

The use of a nonpulsatile pump is one of the most interesting approaches to the development of a circulatory support system for long-term use; including a totally implantable artificial heart. Toward the development of such a device, we selected as a prototype a centrifugal magnet pump in which no seal was required at the rotating part (MD-10; Iwaki Pump, Tokyo, Japan). A nonpulsatile pump has good characteristics as an artificial heart, such as simple structure, no artificial valves, no compliance chamber, relatively good efficiency, easy prediction of durability, and small right pump for total implantation. However, there are several problems, for example, fluid leakage around the seal causing poor durability, the physiological feasibility of nonpulsatile flow, antithrombogenicity, and the occurrence of hemolysis. Fluid leakage is not a problem in this type of non-seal pump. Here we describe the results of our investigations concerning the physiological feasibility of nonpulsatile flow and our attempts to improve the anti-thrombogenicity and to lower the hemolysis rate.

This report discusses the results and conclusions reached from applying acoustic emission monitoring to surveillance of the High Flux Isotope Reactor vessel during pressure testing. The objective of the monitoring was to detect crack growth and/or fluid leakage should it occur during the pressure test. The report addresses the approach, acoustic emission instrumentation, installation, calibration, and test results.

This report discusses the results and conclusions reached from applying acoustic emission monitoring to surveillance of the High Flux Isotope Reactor vessel during pressure testing. The objective of the monitoring was to detect crack growth and/or fluid leakage should it occur during the pressure test. The report addresses the approach, acoustic emission instrumentation, installation, calibration, and test results.

An evaluation has been performed to determine the uncertainty of silicone tracer fluid leakage measurements for an environmental sensing device. The units are tested with an instrument which can measure silicone tracer fluid vapor by the gas chromatography method. An analysis has shown that the measurement uncertainty can be maintained at {plus minus}20% when the volumes used in the procedure are held to a given set of tolerances. 1 fig.

Research on brush seals which was undertaken earlier by Braun et al. (1990) is continued. Particular attention is given to the effects of brush positioning, design, and morphology on sealing surfaces, fluid leakage, and associated pressure drops. It is found that both the structure and the design of the brush are important to its performance. High resistance to the flow of the brush/fence combination can result in catastrophic failure of the brush, while at lower flow resistances, the failure is more gradual.

Fourier transform infrared (FTIR) spectroscopy detected early large increases in fluid leakage from zucchini squash (Cucurbita pepo L.) subjected to a chilling temperature (5C). The increase in fluid leakage (principally water) was found after 1 day at 5C, while surface pitting was detected only after 3 days of storage at 5C. Prestorage temperature conditioning at 15C for 2 days greatly diminished the fluid leakage measured by FTIR spectroscopy after 1 day of storage at 5C. Measuring fluid leakage using FTIR spectroscopy seems to be a promising technique to detect the early onset of chilling injury.

The instability caused by the fluid leakage leads to a limited performance of turbomachines. This instability may be improved by using flexible bearing supports with anisotropic stiffness. With a simplified model this effect is investigated including the influence of many parameters. The results show that the optimum range of anisotropy is strongly dependent on the parameters of rotor-bearing systems. In this paper an explanation from an energy point of view is presented to clarify the different stability behaviors with anisotropic bearing supports. Beside the simplified model, the stability of the complex rotor-bearing system with anisotropic bearing supports is investigated by the finite element model. An example of a typical 900 MW turbogenerator system is presented.