Pumping Capability Research Articles

Arrow International, Inc.

AbstractMedical Instruments &Equipment (MIC: 9.6 SIC: 3841 NAIC:339112)Arrow International develops, manufactures and markets a broad range of clinically advanced, disposable catheters and related products for critical and cardiac care. Co.'s critical care products are used principally for central vascular access in the administration of fluids, drugs, and blood products, patient monitoring and diagnostic purposes. Co.'s cardiac care products include cardiac assist products, such as intra‐aortic balloon pumps and catheters, which are used primarily to augment temporarily the pumping capability of the heart following cardiac surgery, serious heart attack or balloon angioplasty.

Arrow International, Inc.

AbstractMedical Instruments &Equipment (MIC: 9.6 SIC: 3841 NAIC:339112)Arrow International, Inc. develops, manufactures and markets a broad range of clinically advanced, disposable catheters and related products for critical and cardiac care. Co.'s critical care products are used principally for central vascular access in the administration of fluids, drugs, and blood products, patient monitoring and diagnostic purposes. Co.'s cardiac care products include cardiac assist products, such as intra‐aortic balloon pumps and catheters, which are used primarily to augment temporarily the pumping capability of the heart following cardiac surgery, serious heart attack or balloon angioplasty.

Stacked Microchannel Heat Sinks for Liquid Cooling of Microelectronic Components

A novel heat sink based on a multilayer stack of liquid cooled microchannels is investigated. For a given pumping power and heat removal capability for the heat sink, the flow rate across a stack of microchannels is lower compared to a single layer of microchannels. Numerical simulations using a computationally efficient multigrid method [1] were carried out to investigate the detailed conjugate transport within the heat sink. The effects of the microchannel aspect ratio and total number of layers on thermal performance were studied for water as coolant. A heat sink of base area 10 mm by 10 mm with a height in the range 1.8 to 4.5 mm (2–5 layers) was considered with water flow rate in the range 0.83×10−6m3/s (50 ml/min) to 6.67×10−6m3/s (400 ml/min). The results of the computational simulations were also compared with a simplified thermal resistance network analysis.

Coaxial Mixer Hydrodynamics with Newtonian and non‐Newtonian Fluids

AbstractThe performance of several combinations of a wall scraping impeller and dispersing impellers in a coaxial mixer operated in counter‐ and co‐rotating mode were assessed with Newtonian and non‐Newtonian fluids. Using the power consumption and the mixing time as the efficiency criteria, impellers in co‐rotating mode were found to be a better choice for Newtonian and non‐Newtonian fluids. The hybrid impeller‐anchor combination was found to be the most efficient for mixing in counter‐rotating or co‐rotating mode regardless of the fluid rheology. For both rotating modes, it was shown that the anchor speed does not have any effect on the power draw of the dispersing turbines. However, the impeller speed was shown to affect the anchor power consumption. The determination of the minimum agitation conditions to achieve the just suspended state of solid particles (Njs) was also determined. It was found that Njs had lower values with the impellers having the best axial pumping capabilities.

Integrated diamond sapphire laser

We use analytic expressions and simulations to examine a model laser gain element formed by integrating diamond and a solid state laser material, such as, Ti:sapphire. The gain element is designed to provide in a single composite structure the thermal management capabilities of diamond and the optical amplification of the laser material. The model results indicate low temperature and a specific radial dependence of the heat transfer coefficient at the material interfaces are needed to access the highest average powers and highest quality optical fields. We outline paths designed to increase average output power of a lowest order mode laser oscillator based on these gain elements to megawatt levels. The long term goal is economically viable solar power delivered safely from space. The short term goal is a design strategy that will facilitate "proof of principle" demonstrations using currently accessible optical pump and thermal management capabilities.

Role of cardiac power in heart failure.

The heart is a muscular mechanical pump with an ability to generate both flow (cardiac output) and pressure. The product of flow output and systemic arterial pressure is the rate of useful work done, or power output. Cardiac pumping capability can be defined as the cardiac power output (CPO(max)) achieved by the heart during maximal stimulation. Cardiac reserve is the increase in power output as the cardiac performance is increased from the resting to the maximally stimulated state. Recently, several studies have shown that CPO(max), a direct indicator of overall cardiac function, measured directly or as an approximation, is a major determinant of exercise capacity and a most powerful predictor of prognosis for patients with chronic heart failure. The same holds true in acute heart failure, where it is also useful in subclassifying the conditions to select the appropriate treatment.

Conserving One Water Source at the Expense of Another: The Role of Surface Water Price in Adoption of Wells in a Conjunctive Use System

One potential side-effect of irrigation water rate reform is groundwater substitution. As surface water prices rise, irrigators may find it cheaper to rely on on-farm wells than a regional irrigation district. The impact of surface water price on well adoption is examined in a conjunctive use system where both surface water and groundwater are used to meet irrigator demand. Results indicate that as the price of surface water approaches 62% of the marginal cost of pumping groundwater, irrigators are more likely to have on-farm pumping capabilities. This result suggests that proposed water rate reforms by the United States Bureau of Reclamation may result in irrigators substituting groundwater for surface water by adopting on-farm wells.

Li 3: first step studies of a liquid lithium limiter

Carbon (graphite) is the most popular material in use for today's Tokamak first wall components. However, there are real concerns as to its ability to sustain reactor grade conditions, and alternative concepts are envisaged for future fusion reactors. One is the use of a liquid metal surface, which offers several attractive advantages: direct removal of the heat, high pumping capability, insensibility to neutron irradiation, self repairing in case of over-heating, etc. A preliminary study of a liquid lithium limiter has been carried out for Tore Supra, the only Tokamak that has been equipped from its first day of operation with actively cooled first wall elements (with carbon and CFC surfaces). This study is for a relatively small limiter module, with the aim of characterising the interaction of a high performance plasma with a liquid surface in fusion relevant conditions. Up to 5 l/s of liquid lithium flows over a 0.5 m 2 surface, during 20–100 s. The heat removal capability of such a module could reach 1 MW steady state, with a maximum heat flux of 6 MW/m.

Power scaling of diode-pumped Nd:YVO/sub 4/ lasers

The evaluation of pump capability and scaling the output power of Nd:YVO/sub 4/ (vanadate) lasers are presented in this paper. Taking into account thermal fracture limitation and fundamental mode operation, systematic investigations of vanadate crystals have been conducted in an effort to scale the output power of diode-pumped lasers to higher levels. Based on the limitation of pump power, the input versus output power and beam propagation factor of vanadate lasers are optimized with knowledge of the thermal lensing effect and maximum pump power. The theoretical analyzes provide a good prediction for the output power of diode-pumped Nd:YVO/sub 4/ lasers, which is in agreement with the experiment. A practical example of a single-end-pumped vanadate laser is demonstrated with continuous-wave output powers of 9.8 W in the TEM/sub oo/ mode and 12.4 W in multimode.

Deuterium plasma interactions with liquid gallium

Liquid metals such as gallium, tin and lithium are potential plasma-facing materials that may be used to withstand the high heat and particle fluxes in a fusion plasma environment. The interaction of plasma with liquid gallium surfaces has been examined experimentally because of the liquid's wide temperature range (303-2478 K) and relatively low chemical reactivity. The deuterium retention in liquid gallium samples following plasma exposure in the PISCES experimental plasma device is measured using thermal desorption spectroscopy and is found to be independent of exposure temperature. The retention level saturates at a value of roughly 3×1023 D m-3 (or about 5 ppm) for sample exposure temperatures ranging from 333 to 800 K and incident ion fluences up to 1.5×1026 D m-2. Results from the analyses of the surface after plasma exposure using Auger electron spectroscopy is reported. Micropitting is observed in scanning electron microscope pictures taken after plasma exposure and after resolidification of the gallium surface. Calculations based on the observed retained concentration of deuterium in gallium show that the pumping capabilities of a flowing gallium surface will be small. In addition, measurements of the erosion yield of deuterium-bombarded gallium are presented and compare favourably with results from sputtering yield calculations.

Flow patterns and mixing mechanisms in the screw mixing element of a co‐rotating twin‐screw extruder

AbstractNon‐Newtonian and non‐isothermal flow simulations based on 3‐D FEM were applied to a special and conventional elements of a twin‐screw extruder. The screw mixing element (SME), a kind of special element, was a distributive mixing promoter consisting of a standard screw profile with slots cut across the flight tip to increase leakage flow. The full flight screw (FF) and the kneading block (KB) were examined as conventional elements in order to contrast the mixing behavior with the SME. The accuracy of numerical results was verified by experimentally measuring pressure and temperature. Additionally, marker particle tracking analysis was carried out to evaluate the distributive and dispersive mixing. Using the above analyses, the following results were obtained: The pumping capability of the SME was smaller than that of the FF and was the same as for the KB. The SME suppressed heat generation and showed the lowest temperature distribution of the three elements. For distributive mixing, the SME showed the best performance judging from the mixing coefficient G, residence time distribution, and area stretch distribution based on a laminar mixing mechanism. A higher rotational speed achieved better distributive mixing performance. For dispersive mixing defined by stress distribution, the SME showed the second best performance next to the KB. It also showed better dispersive mixing performance with increasing rotational speed. The SME had the advantages of low heat generation and good distributive mixing.

Helium and neon enrichment studies in the JET Mark IIAP and Mark IIGB divertors

Adequate helium enrichment and exhaust have beenachieved in reactor relevant ELMy H mode plasmas in JETperformed in the Mark II divertor geometry. These quantities,describing the retention of impurities in divertors, have beenexperimentally inferred from CXRS measurements in the coreplasma, and from a spectroscopic analysis of a Penning gaugedischarge in the exhaust gas. The retention of helium was foundto be sufficient with respect to the requirements in a next stepdevice, with helium enrichment factors exceeding 0.1 in highdensity ELMy H mode discharges. With increasing core plasmadensity the helium partial pressure in the exhaust channelincreases. While in L mode plasmas the helium enrichmentdecreases with increasing core plasma density, it remains almostconstant in ELMy H mode plasma. The noble gas neon is betterenriched in the divertor at high core plasma densities in bothconfinement regimes. These experimental results can be explainedby the significant differences between the penetration depths ofthe impurity neutrals and by their subsequent different impuritytransport mechanisms. Analytical and numerical analyses of theseplasmas using the impurity code package DIVIMP/NIMBUS supportthe proposition that, owing to their much longer ionization meanfree path, helium particles can escape from the divertor chamberas neutrals, while neon escapes by means of ion leakage.Consequently, the divertor plasma conditions strongly influencethe noble gas compression and enrichment. Variations of thedivertor plasma configuration and modifications to the divertorgeometry have enhanced the pumping capabilities of the tokamak,but have been found not to affect the helium enrichment.

Appraisal of Fluid Dynamic Efficiency of Retreated-Blade and Turbofoil Impellers in Industrial-Size CSTRs

In this work, we examine the performances of two different impellers produced for glass-lined industrial vessel installations. Starting from an experimental evaluation of the power number−Reynolds number curve, we exploit fully three-dimensional, time-dependent fluid dynamic simulations to identify the optimal operating conditions for the widely used retreated-blade impeller and the newer turbofoil turbine. We calculate the power consumption, stirring capability, and pumping efficiency with the final aim of finding guidelines to select the best impeller/vessel configuration. Results show that the turbofoil turbine is more efficient than the retreated-blade impeller in terms of pumping capability and pumping efficiency for operating conditions corresponding to Reynolds numbers larger than 3000. A detailed description of the fluid dynamic field is used to explain and justify the macroscopic evidence.

Deep karst conduits, flooding, and sinkholes: lessons for the aggregates industry

Limestone aggregate quarries in deeply penetrating karst terrain are often at considerable risk of artesian inflow from groundwater or surface water channeled through the karstic aquifer. The inflow occurs through what are likely to be complex conduits that penetrate hundreds of feet into bedrock. Rates of inflow can exceed the operation's pumping capabilities proving to be uneconomic to manage over the long term. Over time, inflow rates can increase dramatically as turbulent flow through the conduit erodes its soft residual clay-rich fill. One recent investigation observed an inflow rate of more than 40,000 gpm from a surface water source. Floodwater persistently laden with sediment is an indicator of conduit washout and implies increasing inflow rates over time. Conduits carrying floodwater can exist in a variety of forms: along deeply penetrating geologic faults, joints, or following the path of preferentially eroded bedding. Preferential structural deformation along faults or bedding can enhance dissolution during subsequent interaction with groundwater. The resulting conduit may be a complex combination of many geological features, making the exploration and remediation of the pathway difficult. Sinkholes at the site can occur within several contexts. Pre-existing subsidence structures can reactivate and subside further, forming new collapse sinkholes within soil directly overlying the conduit. Cover-collapse sinkhole development can be a direct result of increasing downward groundwater velocities and subsurface erosion associated with the enlargement of a conduit. Normal operation events such as a quarry blast can also provide a significant new linkage between the groundwater and the quarry, allowing rapid drainage of the groundwater reservoir. With such drainage and erosion of karst-fill, sinkholes will develop over localized water table depressions, most significantly over enhanced permeability zones associated with fractures. Paradoxically, although the rise in quarry water level will lead to regional reduction in the hydraulic gradients, on local scales, drainage of the groundwater reservoir increases gradients and leads to the development of cover-collapse sinkholes. Recommended methods for preliminary site investigation can include a detailed review of geological literature and drilling logs to compile a conceptual model of the site. A fracture trace analysis with EM geophysics can confirm the locations of major faults and fractures. Fingerprinting of the various water sources to the quarry and the water in the quarry is an inexpensive and effective means of identifying the source and likely direction of the groundwater and surface water flow. Automated geophysical equipment on the market for performing rapid resistivity and microgravity surveys speeds up the site screening process during reconnaissance exploration for deep structure. It is recommended that mine planning fully incorporate this information so that quarry operators can take proactive measures to avoid catastrophic and costly flooding events.

Characterization of emeA, a NorA homolog and multidrug resistance efflux pump, in Enterococcus faecalis.

We hypothesized that multidrug resistance efflux pumps (MDRs) may be contributing to the drug resistance of enterococci. We recently identified potential MDR-encoding genes in the Enterococcus faecalis V583 genome. Among the putative MDRs, we found a gene that encodes a NorA homolog and have characterized this enterococcal MDR in the present study. A mutant from which the enterococcal NorA homolog has been deleted has reduced resistance to several NorA substrates. Complementation of the deletion mutant with the wild-type gene verified the involvement of this enterococcal gene in resistance to ethidium bromide (EtBr) and norfloxacin. Known MDR inhibitors (reserpine, lansoprazole, and verapamil) inhibit the efflux of EtBr and norfloxacin in wild-type strain OG1RF. A fluorescence assay with EtBr allowed us to quantitate the efflux capability of the enterococcal NorA pump. On the basis of these results, we have named this enterococcal gene emeA (enterococcal multidrug resistance efflux).

Heme-copper oxidases with modified D- and K-pathways are yet efficient proton pumps

The cytochrome aa 3-type quinol oxidase from the archaeon Acidianus ambivalens and the ba 3 -type cytochrome c oxidase from Thermus thermophilus are divergent members of the heme-copper oxidase superfamily of enzymes. In particular they lack most of the key residues involved in the proposed proton transfer pathways. The pumping capability of the A. ambivalens enzyme was investigated and found to occur with the same efficiency as the canonical enzymes. This is the first demonstration of pumping of 1 H +/electron in a heme-copper oxidase that lacks most residues of the K- and D-channels. Also, the structure of the ba 3 oxidase from T. thermophilus was simulated by mutating Phe274 to threonine and Glu278 to isoleucine in the D-pathway of the Paracoccus denitrificans cytochrome c oxidase. This modification resulted in full efficiency of proton translocation albeit with a substantially lowered turnover. Together, these findings show that multiple structural solutions for efficient proton conduction arose during evolution of the respiratory oxidases, and that very few residues remain invariant among these enzymes to function in a common proton-pumping mechanism.

Planning and Hazards of Spill Response in Antarctica

ABSTRACT Antarctica is unique in many ways that greatly add to the complexity of spill response. McMurdo Station is the largest of all Antarctic facilities (> 1,300 people in summer, <200 people in winter) and has a storage capacity of over 11 million gallons. A single tanker arriving in February each year supplies fuel, which is augmented by a minor amount supplied by U.S. Coast Guard icebreaker. Waterborne spill response equipment is operationally hazardous to use because of broken ice conditions, limited open water, and difficulty of putting equipment into the water. Operating from shore is preferred as the station has extensive pumping, hose, and storage capability. During major spills, alternative response techniques, particularly burning, would be favorably considered. Additional support from outside Antarctica would not be expected to arrive for several days at best. Outside of McMurdo Station, seasonal field camps are supplied by airlift, and oil is stored in metal drums placed within a containment area. Transport to South Pole Station is by skiequipped C-130 aircraft, and storage is in a new, multitank facility with containment. Oil spills on the ice sheet are unique in that the oil penetrates deep into the snow, making its capture and recovery very difficult. Additionally, because of subzero temperatures, response is very weather dependent, and protection is needed to fully avoid contact with the spilled material.

Multi-machine modelling of divertor geometry effects

The design and construction of advanced divertors has been one of the main topics of tokamak research during the last decade. The design of such divertors has been carried out by using 2-D plasma edge modelling codes. Many of the predictions from the modelling, which guided the optimisation procedure, have been demonstrated experimentally such as: larger operating density range for partially detached plasmas in vertical divertors compared to horizontal ones, improvement of the divertor pumping capability with more closed divertors and corresponding changes in recycling impurity exhaust following predictions. New phenomena that were hinted at by modelling but not clearly quantified, such as the increase in radiative capability of the divertor induced by the geometry, have been measured and understood by 2-D modelling. Divertor flows determined by divertor sources, which are in turn determined by the geometry, show the expected qualitative trends but detailed modelling which includes plasma drifts, not yet carried out, is required to sort out the effects of drifts and particle sources.

Measuring of Velocity Distributions in the Nip Region of a Co-Rotating Twin-Screw Extruder

Self wiping co-rotating twin-screw extruders are used widely in food, polymer and pharmaceutical industries. Some of their advantages over single-screw extruders are their flexibility, efficient mixing and pumping capabilities. These attributes of twin-screw extruders are ascribed to the intermeshing region between the two screws (nip region). Measurement of velocity profiles in the nip region of a twin-screw extruder offers a method to elucidate the transport phenomena. Velocity field in the nip region of a co-rotating twin screw extruder was measured using laser Doppler anemometry for a Newtonian model fluid. The effect of screw speed was investigated. Two velocity components, namely transverse and axial were measured. Whilst the axial velocity component varied significantly with respect to the angular rotation of the screw shaft, the transverse velocity component was almost uniform. Contour plots revealed that the velocity distributions were asymmetrical with respect to the middle of the channel.

Design and characterization of high capacity nonevaporable getter pumps embedded inside the interaction regions of DAΦNE

The DAΦNE Φ-factory is a twin-ring 510 MeV e+e- collider facility under commissioning at INFN-LNF in Frascati. With a stored beam current of 5.3 A, a mean pressure of 1.3×10−9 mbar is required in each ring. For the KLOE interaction region, where a mean pressure of the order of 1.3×10−10 mbar is required, an embedded nonevaporable getter (NEG) pump with a CapaciTorr®-type structure was chosen mainly because of the unavailability of room for the installation of lumped pumps and to take maximum advantage of the sorption capability of the NEG pump for CO in the UHV operating conditions of the machine. A NEG pumping system of the kind discussed in this article seemed to be particularly suitable for the KLOE experiment, where limited servicing and high reliability is required. In this article we report on the design and characterization of both the first pump prototype, fitted with St-172 NEG alloy and the final pump version, where St-185 NEG alloy was used.