scholarly journals Homology of GL over infinite fields outside the stability range

2021 ◽  
pp. 106916
Author(s):  
Behrooz Mirzaii
Keyword(s):  
Stability Range ◽  
The Stability

scholarly journals Influence of the Al content on the phase transformations in Cu-Al-Ag alloys

2003 ◽  
Vol 28 (1) ◽  
pp. 33-38 ◽  
Author(s):  
A. T. Adorno ◽  
A. V. Benedetti ◽  
R. A. G. da Silva ◽  
M. Blanco
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Transition Temperature ◽  
Phase Transformations ◽  
Decomposition Reaction ◽  
Phase Decomposition ◽  
Stability Range ◽  
X Ray ◽  
Al Content ◽  
The Stability

The influence of the Al content on the phase transformations in Cu-Al-Ag alloys was studied by classical differential thermal analysis (DTA), optical microscopy (OM) and X-ray diffractometry (XRD). The results indicated that the increase in the Al content and the presence of Ag decrease the rate of the <FONT FACE=Symbol>b</font>1 phase decomposition reaction and contribute for the raise of this transition temperature, thus decreasing the stability range of the perlitic phase resulted from the b1 decomposition reaction.

scholarly journals Modeling and Designing a Hydrostatic Transmission With a Fixed-Displacement Motor

1998 ◽  
Vol 120 (1) ◽  
pp. 45-49 ◽  
Author(s):  
N. D. Manring ◽  
G. R. Luecke
Keyword(s):  
Order System ◽  
Axial Piston Pump ◽  
Third Order ◽  
Stability Range ◽  
Hydrostatic Transmission ◽  
Control Gain ◽  
Variable Displacement ◽  
Linearized System ◽  
The Stability ◽  
Axial Piston

This study develops the dynamic equations that describe the behavior of a hydrostatic transmission utilizing a variable-displacement axial-piston pump with a fixed-displacement motor. In general, the system is noted to be a third-order system with dynamic contributions from the motor, the pressurized hose, and the pump. Using the Routh-Hurwitz criterion, the stability range of this linearized system is presented. Furthermore, a reasonable control-gain is discussed followed by comments regarding the dynamic response of the system as a whole. In particular, the varying of several parameters is shown to have distinct effects on the system rise-time, settling time, and maximum percent-overshoot.

Aqueous nonelectrolyte solutions — Part XX: Formula of structure I methane hydrate, congruent dissociation melting point, and formula of the metastable hydrate

2003 ◽  
Vol 81 (12) ◽  
pp. 1443-1450 ◽  
Author(s):  
David N Glew
Keyword(s):  
Melting Point ◽  
Equilibrium Constant ◽  
Methane Hydrate ◽  
Equilibrium Constants ◽  
Stability Range ◽  
Congruent Melting Point ◽  
Quadruple Point ◽  
Dissociation Equilibrium ◽  
Metastable Structure ◽  
The Stability

Sixteen new measurements of high precision for structure I methane hydrate with water between 31.93 and 47.39 °C are shown to be metastable and exhibit higher methane pressures than found by earlier workers. Comparison of earlier measurements between 26.7 and 47.2 °C permit positive identification of the structure II and the structure I hydrates. Forty-nine equilibrium constants Kp(h1[Formula: see text]l1g) for dissociation of structure I methane hydrate into water and methane, 32 between –0.29 and 26.7 °C for the stable hydrate and 17 between 31.93 and 47.39 °C for the metastable hydrate, are best represented by a three-parameter thermodynamic equation, which indicates a standard error (SE) of 0.63% on a single Kp(h1[Formula: see text]l1g) determination. The congruent dissociation melting point C(h1l1gxm) of metastable structure I methane hydrate is at 47.41 °C with SE 0.02 °C and at pressure 505 MPa. The congruent equilibrium constant Kp(h1[Formula: see text]l1g) is 102.3 MPa with SE 0.2 MPa. ΔH°t(h1[Formula: see text]l1g) is 62 281 J mol–1 with SE 184 J mol–1, and the congruent formula is CH4·5.750H2O with SE 0.059H2O. At the congruent point, ΔV(h1[Formula: see text]l1g) is zero within experimental precision, and its estimate is 1.3 with SE 1.6 cm3 mol–1. The stability range of structure I methane hydrate with water extends from quadruple point Q(s1h1l1g) at –0.29 °C up to quadruple point Q(h1h2l1g) at 26.7 °C, and its metastability range with water extends from 26.7 °C up to the congruent dissociation melting point C(h1l1gxm) at 47.41 °C. Key words: methane hydrate, clathrate structure I, metastability range, dissociation equilibrium constant, formula, congruent melting point, metastability of structure I hydrate.

Observation of Less Heat Generation and Investigation of Its Effect on the Stability Range of a Nd:YAG Laser

2000 ◽  
Vol 39 (Part 1, No. 6A) ◽  
pp. 3419-3421 ◽  
Author(s):  
Chao-Chia Cheng ◽  
Tong-Long Huang ◽  
Sheng-Hsiung Chang ◽  
Hung-Sheng Tsai ◽  
Hai-Pei Liu
Keyword(s):  
Heat Generation ◽  
Nd:Yag Laser ◽  
Stability Range ◽  
The Stability

scholarly journals Adaptive Control of Electromagnetic Suspension System by HOPF Bifurcation

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Aming Hao ◽  
Xiaolong Li ◽  
Longhua She
Keyword(s):  
Adaptive Control ◽  
Hopf Bifurcation ◽  
Large Scale ◽  
Stability Range ◽  
Hopf Bifurcation Point ◽  
Maglev System ◽  
Large Scale Disturbance ◽  
Excited Vibration ◽  
Parameter Variance ◽  
The Stability

EMS-type maglev system is essentially nonlinear and unstable. It is complicated to design a stable controller for maglev system which is under large-scale disturbance and parameter variance. Theory analysis expresses that this phenomenon corresponds to a HOPF bifurcation in mathematical model. An adaptive control law which adjusts the PID control parameters is given in this paper according to HOPF bifurcation theory. Through identification of the levitated mass, the controller adjusts the feedback coefficient to make the system far from the HOPF bifurcation point and maintain the stability of the maglev system. Simulation result indicates that adjusting proportion gain parameter using this method can extend the state stability range of maglev system and avoid the self-excited vibration efficiently.

The resonant valley suppression of a hydraulic shaking table by using adaptive spectral line enhancer

2018 ◽  
Vol 232 (10) ◽  
pp. 1379-1388
Author(s):  
Tao Wang ◽  
Jinchun Song
Keyword(s):  
Spectral Line ◽  
Coupling Effect ◽  
Resonance Effect ◽  
Shaking Table ◽  
Resonance Phenomenon ◽  
Resonant System ◽  
Stability Range ◽  
Elastic Load ◽  
Hydraulic Servo ◽  
The Stability

As an electro-hydraulic servo shaking table takes on an elastic load in a vibration test of a 2-mass dynamic system, a mutual coupling effect is exerted between the shaking table and the specimen, which will form a resonant system to weaken the dynamic characteristics of the system. As required by the system bandwidth, the resonant system contains a resonance valley and a resonance peak, and its amplitude commonly surmounts the stability range of the system’s acceleration amplitude. In this article, the resonance phenomenon is analyzed, and the structure and the parameters of the three-state controller are designed on the basis of a pole assignment system. The adaptive spectral line enhancer is adopted to suppress the resonant valley, and the power spectrum is analyzed to experimentally verify that it exerts an anti-resonance effect.

scholarly journals Prismatine: revalidation for boron-rich compositions in the kornerupine group

1996 ◽  
Vol 60 (400) ◽  
pp. 483-491 ◽  
Author(s):  
Edward S. Grew ◽  
Mark A. Cooper ◽  
Frank C. Hawthorne
Keyword(s):  
Boron Content ◽  
Structure Refinement ◽  
Tetrahedral Site ◽  
Granulite Facies ◽  
Sensu Stricto ◽  
Stability Range ◽  
Cell Parameters ◽  
Al Content ◽  
Isomorphic Series ◽  
The Stability

AbstractKornerupine and prismatine were introduced independently by Lorenzen in 1884 (but published in 1886 and 1893) and by Sauer in 1886, respectively. Ussing (1889) showed that the two minerals were sufficiently close crystallographically and chemically to be regarded as one species. However, recent analyses of boron using the ion microprobe and crystal structure refinement, indicate that the boron content of one tetrahedral site in kornerupine ranges from 0 to 1. Kornerupine and prismatine, from their respective type localities of Fiskenæsset, Greenland and Waldheim, Germany, are distinct minerals, members of an isomorphic series differing in boron content. For this reason, we re-introduce Sauer’s name prismatine for kornerupines with B > 0.5 atoms per formula unit (p.f.u.) of 22(O,OH,F), and restrict the name kornerupine sensu stricto to kornerupines with B < 0.5 p.f.u. Kornerupine sensu lato is an appropriate group name for kornerupine of unknown boron content. Kornerupine sensu stricto and prismatine from the type localities differ also in Fe2+/Mg ratio, Si − (Mg + Fe2+ + Mn) content, Al content, F content, colour, density, cell parameters, and paragenesis. Both minerals formed under granulite-facies conditions with sapphirine and phlogopite, but kornerupine sensu stricto is associated with anorthite and hornblende or gedrite, whereas prismatine is found with oligoclase (An9–13), sillimanite, garnet, and/or tourmaline. Occurrences at other localities suggest that increasing boron content extends the stability range of prismatine relative to that of kornerupine sensu stricto.

Gemischte Erdalkalimetall-Trielide AIIM1IIIx M2 III2– x (AII = Ca, Sr, Ba; MIII = Al, Ga, In). Strukturchemische und bindungstheoretische Untersuchungen / Mixed Alkaline Earth Trielides AIIM1IIIx M2III2−x (AII = Ca, Sr, Ba; MIII=Al, Ga, In). A Structural and Theoretical Study

2007 ◽  
Vol 62 (2) ◽  
pp. 177-194 ◽  
Author(s):  
Wiebke Harms ◽  
Marco Wendorff ◽  
Caroline Röhr
Keyword(s):  
Alkaline Earth ◽  
Structural Changes ◽  
General Structure ◽  
Structure Type ◽  
Laves Phases ◽  
Stability Range ◽  
The Stability ◽  
Binary Alkaline ◽  
Structure Calculations ◽  
Stability Ranges

The binary alkaline earth trielides of the composition AIIMIII 2 exhibit a puzzling variety of structure types ranging from electron precise Zintl compounds like CaIn2 and KHg2 (both with networks of four-bonded M− entities) and the AlB2 structure type (with graphite analogue M sheets) to the cubic Laves phases e. g. of CaAl2. The examination of the phase stabilities of mixed compounds AM1IIIx M2III2−x of two trielides allows to separate the stability ranges in a structure map by taking the electronegativity differences of MIII and AII (Δ EN) and the radius ratios (RR = rM/rA) into account: The CaIn2-type is stable at comparatively large RR, for example over the whole range CaGa2 -CaIn2 and even up to CaAl0.6Ga1.4 and CaAl1.2In0.8, and in SrIn2, together with a limited substitution of In by Al or Ga. The KHg2-type is observed in a region of lower RR: In BaIn2, a substitution of In by 50% Al and 30% Ga is possible without a general structure change, in SrAl2 this holds for a content of up to 50% In. At high Δ EN and low RR values (e. g. Sr/Ba-Ga), the ideal AlB2 structure type exhibits a distinct stability range; only for small RR around CaAl2 the MgCu2-type is stable. FP-LAPWband structure calculations of the binary trielides allow to explain the structural changes qualitatively. In the case of the electron precise phases forming the CaIn2, KHg2 or AlB2 structure type, details of the bonding situation (such as M-M distances) as well as differences to other isoelectronic compounds can be rationalized taking the incomplete charge transfer from the alkaline earth towards the triel elements into account. This causes a partial depopulation of some of the bonding and a population of predominantly antibonding states.

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