Dynamic Modeling of Gas Springs

1994 ◽  
Vol 116 (3) ◽  
pp. 414-418 ◽  
Author(s):  
A. A. Kornhauser
Keyword(s):  
Dynamic Modeling ◽  
Basic Design ◽  
Spring Model ◽  
Proper Selection ◽  
Free Piston ◽  
Linear Dynamic ◽  
Stirling Engines ◽  
In Series ◽  
Selection Of

Linear dynamic modeling of gas springs is important for basic design of free piston Stirling engines. The conventional gas spring model, a dashpot in parallel with an ideal spring, gives poor prediction of gas spring performance. The anelastic model presented here consists of two parallel springs, one of which is in series with a dashpot. With proper selection of spring and damping constants, it gives improved prediction of gas spring dynamics.

scholarly journals Linear Dynamic Analysis of Free-Piston Stirling Engines on Operable Charge Pressure and Working Frequency along with Experimental Verifications

2021 ◽  
Vol 11 (11) ◽  
pp. 5205
Author(s):  
Dong-Jun Kim ◽  
Kyuho Sim
Keyword(s):  
Dynamic Analysis ◽  
Phase Angle ◽  
Dynamic Models ◽  
Root Locus ◽  
Free Piston ◽  
Linear Dynamic ◽  
Vibration Model ◽  
Stirling Engines ◽  
Charge Pressure ◽  
Working Frequency

This paper presents a linear dynamic analysis on operable charge pressure and working frequency of free-piston Stirling engines (FPSE) along with experimental verifications. The equations of motion of the FPSE are formulated as a 2-degree-of-freedom (DOF) vibration system of the power piston (PP) and displacer piston (DP), based on the state equation of ideal gas and the isothermal Stirling cycle model. The dynamic models of FPSE we considered are the 1-DOF simple vibration model of each piston and the 2-DOF root locus model of coupled pistons. We developed a test FPSE for verification of the dynamic models and conducted a series of experiments to measure the dynamic behaviors of PP and DP under varying charge pressures for various masses and stiffnesses of the PP. As a result, both prediction models showed good agreements with experimental results. The 1-DOF vibration model was found to be simple and effective for predicting the operating frequency and charge pressure of FPSE. The root locus method showed reasonable predictions with an operation criterion of the PP–DP phase angle of 90°. In addition, the FPSE was confirmed to operate in resonant oscillations when the DP–PP phase angle is 90°, based on analysis of the force vector diagram of the two pistons.

Meriel Talbot and the Society for the Overseas Settlement of British Women, 1919–1937

2017 ◽  
Vol 10 (1) ◽  
pp. 32-52
Author(s):  
Bonnie White
Keyword(s):  
Domestic Service ◽  
Agricultural Workers ◽  
British Government ◽  
Early Failure ◽  
Proper Selection ◽  
Domestic Servants ◽  
Female Workers ◽  
Female Migrants ◽  
Post War ◽  
Selection Of

In 1917 the British government began making plans for post-war adjustments to the economy, which included the migration of surplus women to the dominions. The Society for the Overseas Settlement of British Women was established in 1920 to facilitate the migration of female workers to the dominions. Earlier studies have argued that overseas emigration efforts purposefully directed women into domestic service as surplus commodities, thus alleviating the female ‘surplus’ and easing economic hardships of the post-war period. This article argues that as Publicity Officer for the SOSBW, Meriel Talbot targeted women she believed would be ideal candidates for emigration, including former members of the Women's Land Army and affiliated groups. With the proper selection of female migrants, Talbot sought to expand work opportunities for women in the dominions beyond domestic service, while reducing the female surplus at home and servicing the connection between state and empire. Dominion authorities, whose demands for migrant labour vacillated between agricultural workers during the war years and domestic servants after 1920, disapproved of Talbot's efforts to migrate women for work in agriculture. Divergent policies led to the early failure of the SOSBW in 1923.

scholarly journals Design Concepts for NiTiNOL Wires to Function as a Sensor

2021 ◽  
Author(s):  
D. Josephine Selvarani Ruth
Keyword(s):  
Shape Memory Alloy ◽  
Electrical Resistance ◽  
Nickel Titanium ◽  
The Other ◽  
Sensing Element ◽  
Proper Selection ◽  
Design Concepts ◽  
Mechanical Element ◽  
Selection Of ◽  
Inverse Hysteresis

AbstractNickel Titanium Naval Ordinance Laboratory (NiTiNOL) is widely called as a shape memory alloy (SMA), a class of nonlinear smart material inherited with the functionally programmed property of varying electrical resistance during the transformation enabling to be positioned as a sensing element. The major challenge to instrument the SMA wires is to suppress the wires’ nonlinearity by proper selection of two important factors. The first factor is influenced by the mechanical biasing element and the other is to identify the sensing current for the sensing device (SMA wires + biasing). This paper focuses on developing SMA wires for sensing in different orientation types and configurations by removing the non-linearity in the system’s output by introducing inverse hysteresis to the wires through the passive mechanical element.

scholarly journals Internet page content analysis of north European Sea ports

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Olli-Pekka Hilmola ◽  
Andres Tolli ◽  
Ain Kiisler
Keyword(s):  
Content Analysis ◽  
Environmental Issues ◽  
Basic Design ◽  
Time Period ◽  
Long Time ◽  
Sea Ports ◽  
Selection Of

Abstract This study analyses 98 Internet pages of sea ports located in Sweden, Finland and Estonia during years 2017–2019. Aim of the study is to find, how website basic design is completed (colours and languages), how slogans, environmental issues, statistics and hinterland transports are reported. Based on the analysis, it appears as rather common that sea ports follow conservative selection of colours in their websites, where blue and white are clearly most popular. Typically, English and Swedish are as the most common used language, followed by Finnish, Russian and Estonian. In some rare cases, websites are offered in Chinese or German. Larger sea ports do have clear “slogans”, where smaller ones are just having lengthy justification for their existence. Environmental issues are increasing concern among sea ports, and these are mostly mentioned in details within Swedish actors. Providing statistics varies among companies, and in some sea ports these are provided from very long time period, where in others from just previous years or then only from last year (or even at all). It is common for companies to report that they have sustainable hinterland access, railway available.

A Non-Normality Measure of the Condition Number for Monitoring and Control

1997 ◽  
Vol 119 (2) ◽  
pp. 217-222 ◽  
Author(s):  
Kunsoo Huh ◽  
Jeffrey L. Stein
Keyword(s):  
Optimal Control ◽  
Condition Number ◽  
Minimization Problem ◽  
Monitoring And Control ◽  
Proper Selection ◽  
Modal Structure ◽  
L2 Norm ◽  
And Control ◽  
Normality Measure ◽  
Selection Of

Because the behavior of the condition number can have highly steep and multi-modal structure, optimal control and monitoring problems based on the condition number cannot be easily solved. In this paper, a minimization problem is formulated for κ2(P), the condition number of an eigensystem (P) of a matrix in terms of the L2 norm. A new non-normality measure is shown to exist that guarantees small values for the condition number. In addition, this measure can be minimized by proper selection of controller and observer gains. Application to the design of well-conditioned controller and observer-based monitors is illustrated.

scholarly journals Influence of the Chemical Composition on Electrical Conductivity and Mechanical Properties of the Hypoeutectic Al-Si-Mg Alloys

2016 ◽  
Vol 61 (1) ◽  
pp. 353-360 ◽  
Author(s):  
B. Dybowski ◽  
J. Szymszal ◽  
Ł. Poloczek ◽  
A. Kiełbus
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Chemical Composition ◽  
Aluminium Alloys ◽  
Mg Alloys ◽  
High Electrical Conductivity ◽  
Transportation Industry ◽  
Proper Selection ◽  
Ti Addition ◽  
Selection Of

Due to low density and good mechanical properties, aluminium alloys are widely applied in transportation industry. Moreover, they are characterized by the specific physical properties, such as high electrical conductivity. This led to application of the hypoeutectic Al-Si-Mg alloys in the power generation industry. Proper selection of the alloys chemical composition is an important stage in achievement of the demanded properties. The following paper presents results of the research on the influence of alloys chemical composition on their properties. It has been revealed that Si and Ti addition decreases electrical conductivity of the Al-Si-Mg alloys, while Na addition increases it. The mechanical properties of the investigated alloys are decreased by both silicon and iron presence. Sodium addition increases ductility of the Al-Si-Mg alloys.

scholarly journals Hydrogen Gas Sensors Fabricated on Atomically Flat 4H-SiC Webbed Cantilevers

2008 ◽  
Vol 600-603 ◽  
pp. 1199-1202 ◽  
Author(s):  
Philip G. Neudeck ◽  
David J. Spry ◽  
Andrew J. Trunek ◽  
Laura J. Evans ◽  
Liang Yu Chen ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Rapid Detection ◽  
Hydrogen Gas ◽  
Current Gain ◽  
Proper Selection ◽  
Hydrogen Gas Sensors ◽  
Sensor Current ◽  
Atomically Flat ◽  
Initial Results ◽  
Selection Of

This paper reports on initial results from the first device tested of a “second generation” Pt-SiC Schottky diode hydrogen gas sensor that: 1) resides on the top of atomically flat 4H-SiC webbed cantilevers, 2) has integrated heater resistor, and 3) is bonded and packaged. With proper selection of heater resistor and sensor diode biases, rapid detection of H2 down to concentrations of 20 ppm was achieved. A stable sensor current gain of 125 ± 11 standard deviation was demonstrated during 250 hours of cyclic test exposures to 0.5% H2 and N2/air.

Available Energy: I. Gibbs Revisited; II. Gibbs Extended

1999 ◽  
Author(s):  
Richard A. Gaggioli ◽  
David H. Richardson ◽  
Anthony J. Bowman ◽  
David M. Paulus
Keyword(s):  
The Body ◽  
Nonequilibrium Condition ◽  
Balance Equations ◽  
Proper Selection ◽  
Additive Property ◽  
Property Relations ◽  
Available Energy ◽  
Dead State ◽  
Energy Equilibrium ◽  
Selection Of

Abstract The concept of available energy, as defined by Gibbs (1873b) is revisited. He gave representations of available energy for two circumstances. The first was the available energy of a “body,” for the case when a body, alone, is in a nonequilibrium condition and therefore has energy available. In turn, he presented the available energy of “the body and medium,” for the energy which is available because a body is not in equilibrium with some arbitrarily specified medium. Gibbs’ representations were graphical. Since Gibbs, representations with formulas have been developed and are common, for the “available energy of body and medium.” Gaggioli (1998a, b) has developed formulas which are more general, to represent “the available energy of the body (alone)” and to assign an exergy to subsystems of the body as a measure of each sub-system’s contribution to the available energy. In contrast to the available energy, exergy is an additive property, so that balance equations can be written. And the formulas are independent from any “medium,” which is important both theoretically and practically — because of its relevance to proper selection of “the dead state.” These issues are discussed and extended, after reviewing Gibbs development of available energy and additional concepts which he introduced, such as “available vacuum” and “capacity for entropy.” It is argued that these “availabililty” and “capacity” concepts are all equivalent to one another. In turn, because of interconvertability, it is seen that available energy is something more fundamental than “maximum useful work.” Furthermore, it is illustrated that available energy, equilibrium and stability, and thermostatic property relations are relative, to “constraints.”

Selection of Blood (Packed RBCs) for Transfusion in Newborn Baby up to the Age of 4 Months

2012 ◽  
Vol 1 (1) ◽  
pp. 36-40
Author(s):  
Ghulam Mostafa Khan
Keyword(s):  
Blood Group ◽  
Whole Blood ◽  
Placental Transfer ◽  
Newborn Baby ◽  
Older Children ◽  
Proper Selection ◽  
Group A ◽  
Cross Matching ◽  
Packed Rbcs ◽  
Selection Of

Proper selection of donor’s blood group is essential to prevent transfusion hazards. It is known that ABO antigen is fully developed at birth but the newborn baby does not produce ABO antibodies until 3 to 6 months of age. The ABO antibodies present in the serum of newborn babies are derived from mother’s blood due to placental transfer. So the blood group of the newborn baby is done by ABO antigen grouping (forward grouping) only, antibody grouping (reverse grouping) is not required. In case of transfusion of blood in newborn under 4 months of age, cross-matching of donor’s blood is done with the mother’s blood if it is available. We know, recipient’s same group of blood is always preferable in case of transfusion in adults or older children. But selection of blood for transfusion in the infants under 4 months of age depends on the mother’s blood group as well. If the mother’s blood group differs from the infant’s blood group, the infant’s same group of blood may not be selected for transfusion. For example, if the mother’s blood group is “O” and the newborn blood group is “A” or “B”, infant’s same group “A” or “B” group blood could not be transfused, because the anti-A & anti-B antibodies can be derived in the infant’s serum from mother’s blood which may react with the “A” or “B” antigen of the donor’s blood. In this case “O” group packed RBCs should be selected for transfusion. “O” group whole blood may contain IgG anti-A and anti-B antibodies in the plasma which can react with the “A” or “B” antigen of the infant’s blood. So to avoid anti-A & anti-B antibodies in “O” group, plasma should be discarded and the packed RBCs should be transfused. In case of Rh-negative mother with Rh positive baby, Rh antibody may develop in mother’s blood and Rh antibody may enter into baby’s circulation, in this case the infant should be transfused with Rh-negative blood to avoid Rh antigen & antibody reaction. So for the selection of blood for transfusion in newborn baby up to the age of 4 months mother’s blood group is important to select the appropriate blood. DOI: http://dx.doi.org/10.3329/jemc.v1i1.11138J Enam Med Col 2011; 1(1): 36-40

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