scholarly journals Tunable-Volume Handheld Pipette Utilizing a Pneumatic De-Amplification Mechanism

2014 ◽  
Author(s):  
Justin Beroz ◽  
Sheng Jiang ◽  
John Lewandowski ◽  
A. John Hart
Keyword(s):  
Liquid Volume ◽  
Leading Order ◽  
Air Volume ◽  
Accuracy And Precision ◽  
Extended Range ◽  
Piston Mechanism ◽  
Amplification Mechanism ◽  
Entrapped Air ◽  
Piston Stroke ◽  
Careful Design

We present the design, analysis, and validation of a tunable-volume handheld pipette that enables precise drawing and dispensing of ml and μl liquid volumes. The design builds upon the standard mechanism of a handheld micropipette by incorporating an elastic diaphragm that de-amplifies the volume displacement of the internal piston via compression of an entrapped air volume. The degree of de-amplification is determined by the stiffness of the elastic diaphragm and the amount of entrapped air. An analytical model of the diaphragm mechanism is derived, which guides how to achieve linear de-amplification over an extended range where leading-order nonlinear contributions are significant. In particular, nonlinearities inherent in the mechanical behavior of the diaphragm and entrapped air volume may exactly cancel one another by careful design of the pipette’s parameter constants. This linearity is a key attribute for enabling the pipette’s tunable volumetric range, as this allows diaphragms with different stiffnesses to be selectively used with a conventional linear-stepping piston mechanism. Design considerations regarding the range, accuracy, and precision of the proposed pipette are detailed based on the model. Additionally, we have constructed a handheld prototype that uses a planar latex sheet as the diaphragm. Our pipetting experiments validate the derived model and exhibit linearity between the piston stroke and drawn liquid volume. We propose that this design enables a single handheld mechanical pipette to achieve drawing and dispensing of liquids over a 1μl-10ml range (i.e., the range of the entire micropipette suite), with volumetric resolution and precision comparable to commercially available counterparts.

scholarly journals A CFD analysis of room aspect ratio on the effect of buoyancy and room air flow

2007 ◽  
Vol 11 (4) ◽  
pp. 79-94 ◽  
Author(s):  
Brajesh Tripathi ◽  
Moulic Sandipan ◽  
Late Arora
Keyword(s):  
Temperature Distribution ◽  
Distribution System ◽  
Air Distribution ◽  
Cooling Load ◽  
Cfd Analysis ◽  
Uniform Temperature ◽  
Air Volume ◽  
Recent Developments ◽  
Careful Design ◽  
Occupied Zone

Comfort conditions in air-conditioned rooms require that temperature in the occupied zone should not vary by more than 1?C and velocity, every where in the room, should be less than 0.15 m/s so that occupants do not feel draft. Recent developments in providing effective insulation and making leak tight buildings are considerably reduced the cooling load requirements and the supply airflow rates. Obtaining uniform temperature distribution with reduced air volume flow rates requires careful design of air distribution system. This study aims to find velocity and temperature distribution in the room towards this end.

Simulation of Air Entrapment by a Plunging Liquid Jet of Finite Length

Volume 1 ◽  
2004 ◽  
Author(s):  
Paul S. Krueger ◽  
Razvan Bidoae ◽  
Peter E. Raad
Keyword(s):  
Finite Length ◽  
Liquid Jet ◽  
Air Entrapment ◽  
Air Bubble ◽  
Pool Surface ◽  
Air Volume ◽  
Large Pool ◽  
Vorticity Generation ◽  
Simulation Results ◽  
Entrapped Air

The impingement of a finite length round water jet on a large pool of water was simulated numerically using a 3D Eulerian-Lagrangian Marker and Micro-Cell (ELMMC) method. The method allowed simulation of the initial impact of the jet on the pool surface, the deformation of the pool surface by the falling jet, and, under certain conditions, the entrapment of an air bubble as the pool closes in on the jet. The conditions considered were for ratios of jet length to radius (h/r) in the range of 4 to 25 and jet Froude number in the range of 16 to 74. The results agreed with previous experimental observations by Oguz et al. (J. Fluid Mech., 294, 1995) in terms of entrapped air volume and the possible geometries of entrapped bubbles (viz., toroidal or spheroidal). The simulation results also allowed for a detailed study of effects difficult to discern experimentally, such as vorticity generation and differences in entrapped air volume between toroidal and spheroidal bubbles.

Pumping Underground Extended-Range Application Practice and Process Analysis with Mechanics

2012 ◽  
Vol 164 ◽  
pp. 371-374
Author(s):  
Li Jun Qiu ◽  
Jia Yang
Keyword(s):  
Process Analysis ◽  
Sucker Rod ◽  
Extended Range ◽  
Limit Position ◽  
Piston Stroke

The extended range device for hanging above the pump to increase the pump piston stroke.The diameter of the extended range is greater than the diameter of the tubing. The extended range and pump tube connection transition tubing and excessive sucker rod. Transition tubing and excessive sucker rod length is accurate. The limit position pump piston stroke is not from the pump body and not collide with the pump with the pump. The extended-range device installation location is away from two pumping tubing length.The output rod of extended-range device does not bear the weight of the sucker rod

scholarly journals Numerical study on dynamic behavior of entrapped air in a partially filled pipe

2021 ◽  
Vol 83 (4) ◽  
pp. 771-780
Author(s):  
Hengliang Guo ◽  
Ye Guo ◽  
Biao Huang ◽  
Jiachun Liu
Keyword(s):  
Dynamic Behavior ◽  
Peak Pressure ◽  
Numerical Study ◽  
Relative Length ◽  
Time Duration ◽  
Initial Water ◽  
Pipe Length ◽  
System Parameters ◽  
Air Volume ◽  
Entrapped Air

Abstract Rapid filling in horizontal partially filled pipes with entrapped air may result in extreme pressure transients. This study advanced the current understanding of dynamic behavior of entrapped air above tailwater (the initial water column with a free surface in a partially filled pipe) through rigid-column modeling and sensitivity analysis of system parameters. Water and air were considered as incompressible fluid and ideal gas, respectively, and the continuity and momentum equations for water and a thermodynamic equation for air were solved by using the fourth order Runge-Kutta method. The effects of system parameters were examined in detail, including tailwater depth, entrapped air volume, driving head, pipe friction, and relative length of entrapped air and pipe. The results indicate that the presence of tailwater can mitigate the peak pressure when with identical initial volumes of entrapped air, as it can be considered to reflect a certain amount of loss of the net driving head. However, the peak pressure can increase as much as about 45% for the cases with fixed pipe length, due to the reduction in the initial entrapped air volume. The rise time for the first peak pressure was closely related to pipe friction, whereas the oscillation period (defined as the time duration between the first and second peaks) was virtually irrelevant. The applicability of the rigid-column model was discussed, and a time scale relevant indicator was proposed. When the indicator is larger than 20, the relative difference between the peak pressure estimation and experimental measurements is generally below 5%.

Effect of Buoyancy on Room Air Flow

2004 ◽  
Author(s):  
B. Tripathi ◽  
R. C. Arora ◽  
S. G. Moulic
Keyword(s):  
Temperature Distribution ◽  
Distribution System ◽  
Coanda Effect ◽  
Air Distribution ◽  
Air Volume ◽  
Recent Developments ◽  
Coandǎ Effect ◽  
The Right ◽  
Careful Design ◽  
Occupied Zone

Thermal comfort and ventilation needs of spaces are met by supplying “conditioned” air, which is a blend of outdoor and recirculated air that has been filtered, heated or cooled, and sometimes humidified or dehumidified. Comfort conditions in air-conditioned rooms require that temperature in the occupied zone should not vary by more than 1°C and velocity, every where in the room, should be less than 0.15 m/s so that occupants do not feel draft. Recent developments in providing effective insulation and making leak tight building shell have considerably reduced the cooling load requirements and the supply airflow rates. Obtaining uniform temperature distribution with reduced air volume flow rates requires careful design of air distribution system. This study aims to find velocity and temperature distribution in the room towards this end. Coanda effect, effect of buoyancy and wall boundary layers has been observed in this investigation. The Coanda effect is observed in all the cases of laminar flow. Cold fluid enters in the room near the ceiling, the flow attaches with the ceiling, comes down along the right wall and goes out from outlet.

An X-ray tomography approach to calculate air volume present in an insulation system sewn with lockstitch and spacer stitch

2020 ◽  
Vol 32 (5) ◽  
pp. 775-788
Author(s):  
Hassan Saeed ◽  
Sybille Krzywinski
Keyword(s):  
Thermal Properties ◽  
Three Dimensional ◽  
Weather Conditions ◽  
Insulation Material ◽  
Insulation System ◽  
Content Type ◽  
X Ray ◽  
Air Volume ◽  
Stitch Length ◽  
Entrapped Air

PurposeSewing is the most widely used and preferred method for manufacturing clothing products for extreme weather conditions and other industrial insulation systems. Multiple layers of functional fabrics in combination with insulation materials are used to thermally insulate precious body heat from its surrounding cold environment. The sewing process fixes the insulation material between the fabric layers. During conventional sewing, the insulation material is compressed along the stitch line. With the compression of the insulation material, entrapped air is forced to leave the insulation material internal structure, and heat loss occurs along the entire length of the stitch line. It results in the deterioration of thermal properties of the end product along the stitch line.Design/methodology/approachThe amount of air, which is a decisive factor for thermal properties of any insulation system, was investigated at the level of a unit stitch length of a lockstitch. Conventional microscopy methods are not suitable to study the compression along the stitch line. With the help of X-ray tomography, the three-dimensional data of a stitch was taken and studied to measure the volume of air. The samples were prepared with conventional lockstitch sewing and a newly developed innovative sewing method “Spacer Stitching.” The results are compared with each other in terms of the amount of air present in a unit stitch length.FindingsCalculations based on X-ray tomography images of lockstitch and spacer stitch revealed that, in the case of lockstitch, a unit stitch has a 15% of its volume made up of material and 85% of its volume by air. In comparison, the spacer stitch with the same sewing and fabric parameters has a material volume of 4.6 % and an air volume of 95.4% in a single stitch.Practical implicationsThe research can positively improve the thermal properties of sewn material made for insulating purposes of conventional clothing as well as of industrial insulations.Originality/valueThere is no literature available which investigates and calculates the amount of air and material present along with a stitch line.

Variable Stroke Piston Mechanism for Spark Ignition Engines

1994 ◽  
Author(s):  
A. H. Elkholy
Keyword(s):  
Internal Combustion Engines ◽  
Combustion Process ◽  
Design Parameters ◽  
Spark Ignition Engines ◽  
Connecting Rod ◽  
Spark Plug ◽  
Engine Cylinder ◽  
Piston Mechanism ◽  
Steady Combustion ◽  
Piston Stroke

Abstract The concept of load control in internal combustion engines by eliminating the inlet throttle and replacing it by controlling the piston stroke has gained great publicity recently. Nevertheless, certain design parameters should be considered in order to make this concept worthwhile. In this study, an optimized mechanism for varying engine stroke has been introduced. A criteria based upon the use of complex numbers technique was used to analyze the mechanism kinematically and dynamically and the results were then verified using graphical solution. The mechanism was found to produce up to 56% stroke variation within the control actuator capabilities. The compression ratio was found unchanged (within ± 6%) which helps maintain steady combustion process. The entire mechanism is well tuned and no spark plug timing adjustment is required during stroke variation. The piston side thrust due to connecting rod angularities was found fairly low and should not impose any wear problems in the engine cylinder walls.

scholarly journals Atmospheric Pressure Change Measurement: An Observational Study

2021 ◽  
Author(s):  
Kuat Oshakbayev ◽  
Gulnara Bedelbayeva ◽  
Khalit Mustafin ◽  
Abdul Sabir ◽  
Attila Tordai
Keyword(s):  
Observational Study ◽  
Study Design ◽  
Atmospheric Pressure ◽  
Pressure Change ◽  
Indirect Measurement ◽  
Liquid Volume ◽  
Change Measurement ◽  
Air Volume

Abstract Introduction: The aim of the study was to show an atmospheric pressure change by indirect measurement in hermetically closed vessels during four years of follow-up.Methods: Study design: an observational study. In hermetically sealed elastic bottles with different liquids were measured differences in liquid and air volumes from baseline to final follow-up period. The physical law of flotation was used to measure liquid and air volume above liquid in bottles. To measure liquid and air (above liquid) volumes in each bottle was used the physical law of buoyancy. The follow-up period was four years.Results: The volumes of liquid and air in all bottles were decreased after the follow-up period to 14.38±2.40 and 36.25±3.37 ml, respectively. Air volume in comparison to liquid volume decreased more than two times significantly (P=0.0007) after the follow-up period.Conclusions: Thus, atmospheric pressure increased during the last 4-year follow-up period. Further investigations are needed.

A Stable Field Emission Electron Source

1977 ◽  
Vol 35 ◽  
pp. 58-59
Author(s):  
W.R. Bottoms ◽  
G.B. Haydon
Keyword(s):  
Field Emission ◽  
Signal To Noise Ratio ◽  
High Brightness ◽  
Electron Sources ◽  
Brightness Field ◽  
Current Densities ◽  
Properties Of Materials ◽  
Stable Field ◽  
Stable Current ◽  
Careful Design

There is great interest in improving the brightness of electron sources and therefore the ability of electron optical instrumentation to probe the properties of materials. Extensive work by Dr. Crew and others has provided extremely high brightness sources for certain kinds of analytical problems but which pose serious difficulties in other problems. These sources cannot survive in conventional system vacuums. If one wishes to gather information from the other signal channels activated by electron beam bombardment it is necessary to provide sufficient current to allow an acceptable signal-to-noise ratio. It is possible through careful design to provide a high brightness field emission source which has the capability of providing high currents as well as high current densities to a specimen. In this paper we describe an electrode to provide long-lived stable current in field emission sources.The source geometry was based upon the results of extensive computer modeling. The design attempted to maximize the total current available at a specimen.

A in Vivo Assay for Standardizing Heparin Preparations

1979 ◽  
Vol 41 (03) ◽  
pp. 576-582
Author(s):  
A R Pomeroy
Keyword(s):  
In Vitro Assays ◽  
British Pharmacopoeia ◽  
In Vitro Method ◽  
Standard Preparation ◽  
Reliable Estimation ◽  
Assay Procedure ◽  
Accuracy And Precision ◽  
Heparin Preparation

SummaryThe limitations of currently used in vitro assays of heparin have demonstrated the need for an in vivo method suitable for routine use.The in vivo method which is described in this paper uses, for each heparin preparation, four groups of five mice which are injected intravenously with heparin according to a “2 and 2 dose assay” procedure. The method is relatively rapid, requiring 3 to 4 hours to test five heparin preparations against a standard preparation of heparin. Levels of accuracy and precision acceptable for the requirements of the British Pharmacopoeia are obtained by combining the results of 3 to 4 assays of a heparin preparation.The similarity of results obtained the in vivo method and the in vitro method of the British Pharmacopoeia for heparin preparations of lung and mucosal origin validates this in vivo method and, conversely, demonstrates that the in vitro method of the British Pharmacopoeia gives a reliable estimation of the in vivo activity of heparin.

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