Log in

Relevant bibliographies by topics / Instability constant / Journal articles

To see the other types of publications on this topic, follow the link: Instability constant.

Journal articles on the topic 'Instability constant'

Author: Grafiati

Published: 30 May 2022

Last updated: 31 May 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Instability constant.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Monastra, A. G., M. F. Carusela, M. V. D’Angelo, and L. Bruno. "Filament instability under constant loads." Journal of Physics: Conference Series 1012 (April 2018): 012010. http://dx.doi.org/10.1088/1742-6596/1012/1/012010.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Wallace, J. M., and E. M. Epperlein. "Weibel instability with constant driving source." Physics of Fluids B: Plasma Physics 3, no. 7 (July 1991): 1579–86. http://dx.doi.org/10.1063/1.859677.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Çakırlı, Ö. "“Constant” eclipsing binary in the instability strip." New Astronomy 37 (May 2015): 70–75. http://dx.doi.org/10.1016/j.newast.2014.12.006.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Alipour, M. J., and A. Lashkari. "Sand instability under constant shear drained stress path." International Journal of Solids and Structures 150 (October 2018): 66–82. http://dx.doi.org/10.1016/j.ijsolstr.2018.06.003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Petrov, A. G., and M. A. Yudin. "Cylinder instability in bounded flow with constant vorticity." Journal of Physics: Conference Series 894 (October 2017): 012126. http://dx.doi.org/10.1088/1742-6596/894/1/012126.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Chan, San To, Stylianos Varchanis, Simon J. Haward, and Amy Q. Shen. "Torsional instability of constant viscosity elastic liquid bridges." Soft Matter 18, no. 10 (2022): 1965–77. http://dx.doi.org/10.1039/d1sm01804c.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

GIDDINGS, STEVEN B. "THE CONFORMAL FACTOR AND THE COSMOLOGICAL CONSTANT." International Journal of Modern Physics A 05, no. 19 (October 10, 1990): 3811–29. http://dx.doi.org/10.1142/s0217751x9000163x.

Full text

Abstract:

The issue of the conformal factor in quantum gravity is examined for Lorentzian signature spacetimes. In Euclidean signature, the “wrong” sign of the conformal action makes the path integral undefined, but in Lorentzian signature this sign is tied to the instability of gravity and once this is accounted for the path integral should be well-defined. In this approach it is not obvious that the Baum-Hawking-Coleman mechanism for suppression of the cosmological constant functions. It is conceivable that since the multiuniverse system exhibits an instability for positive cosmological constant, the dynamics should force the system to zero cosmological constant.

APA, Harvard, Vancouver, ISO, and other styles

8

Matsebula, Lindiwe Fortunate. "Shoulder Function Following Latarjet Procedure for Recurrent Anterior Shoulder Instability." Journal of Orthopaedics & Bone Disorders 5, no. 1 (2021): 1–8. http://dx.doi.org/10.23880/jobd-16000205.

Full text

Abstract:

Introduction: Anterior shoulder dislocation and recurrent glenohumeral instability is very common in the young active population. It is usually caused by trauma, and often compounded by associated bony Bankart and Hill-Sachs lesions, which distort the anatomy. This causes instability and dysfunction of the joint and these can be addressed by, amongst others, a Latarjet surgical procedure. Hypothesis: We hypothesize that since the Latarjet procedure results in stability and good functional outcome, our results are expected to compare favourably to the rest of the published literature. Methods: A retrospective study of 31 patients treated with the Latarjet procedure at Helen Joseph hospital, Johannesburg South Africa was undertaken during the period of January 2005 to December 2013. The minimum follow up was 6 months. Stability was assessed looking at re-dislocation rate and the clinical functional outcome was measured using the Constant Score. Results: There were no shoulder re-dislocations and the mean Constant score was 85.35. 74% had a Constant Score above 80. 68% were pain free and 61% had normal activities of daily living while 68% had a full range of motion and 68% had full power. Conclusion: The Latarjet results in stability and good functional outcome. In our patient cohort, the Latarjet procedure provided reliable stability to the shoulder joint. Pain was alleviated, shoulder muscle power was preserved, range of shoulder motion was restored and patients did return to pre injury activities of daily living.

APA, Harvard, Vancouver, ISO, and other styles

9

Obligado, Martín, Nathanaël Machicoane, Agathe Chouippe, Romain Volk, Markus Uhlmann, and Mickaël Bourgoin. "Path instability on a sphere towed at constant speed." Journal of Fluids and Structures 58 (October 2015): 99–108. http://dx.doi.org/10.1016/j.jfluidstructs.2015.08.003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Tahiri, Abdellah, Mohamed Idiri, and Brahim Boubeker. "Mechanicals Behaviors of Tungsten-Rhenium Alloy Single Crystals from 77K to 300K - Atomic Simulation Study." International Journal of Engineering Research in Africa 50 (September 2020): 177–81. http://dx.doi.org/10.4028/www.scientific.net/jera.50.177.

Full text

Abstract:

The elastic constants of tungsten-rhenium alloy single crystals were calculated by simulation atomic method using embedded method atom of interatomic potential. The found results show that elastic constants are proportional to the rhenium concentration up to 25 at% Re at room temperature. By following, we observed the elastic constant C44 dependency of temperature and decreased of elastic constant C’=1/2(C11-C12) when the Re atom addition increases. We have found that a growing instability of the bcc crystal structure. Our parameter calculation model is in good agreement with experimental data.

APA, Harvard, Vancouver, ISO, and other styles

11

SHIMOKAWA, MICHIKO, and SHONOSUKE OHTA. "ANNIHILATIVE FRACTALS FORMED IN RAYLEIGH-TAYLOR INSTABILITY." Fractals 20, no. 01 (March 2012): 97–104. http://dx.doi.org/10.1142/s0218348x12500090.

Full text

Abstract:

We report on a fractal pattern formed in Rayleight-Taylor instability. The fractal dimension is 1.88 ± 0.06, which is constant in time t > t1 = 70 s. The pattern area decreases according to exp (-t/τ), where t and τ are time and time constant 69.8 s, respectively. τ agrees with t1. This result leads that it is important for the fractal formation that sufficient annihilation of the heavier solution at the surface.

APA, Harvard, Vancouver, ISO, and other styles

12

Nasir, M. N. M., Awang Jusoh, and Alias Khamis. "DC Bus Instability Driving by Photovoltaic Source with Constant Power Load." Applied Mechanics and Materials 313-314 (March 2013): 853–57. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.853.

Full text

Abstract:

This study presented the DC bus instability in distributed power system driving by Photovoltaic (PV) source with constant power load (CPL). The aim of this study is to investigate the effect of PV source towards the performances of DC bus voltage stability using constant power load. The system first was tested using linear DC supply as voltage source and CPL was modeled and connected to the voltage source through LC filter network. A passive damping circuit was chosen to stabilize the DC bus instability. The system was repeated using PV source. PV array was modeled based on the parameters obtained from a commercial PV data sheet. A circuitry simulation was performed under the similar design excluding the DC source in order to investigate DC bus instability. Results showed that the stability of DC bus become unstable when using linear DC voltage supply and slightly affected when using PV source. The instability phenomenon due to the negative incremental impedance of a constant power load can be overcome by using damping technique. For linear DC voltage source, DC bus voltage system tends to oscillate. However, with PV source which is actually a current source input seems not much affecting the DC bus voltage stability.

APA, Harvard, Vancouver, ISO, and other styles

13

MOFFAT, J. W. "GRAVITATIONAL INSTABILITY OF THE VACUUM AND THE COSMOLOGICAL CONSTANT PROBLEM." International Journal of Modern Physics A 20, no. 19 (July 30, 2005): 4683–89. http://dx.doi.org/10.1142/s0217751x05028387.

Full text

Abstract:

A mechanism for suppressing the cosmological constant is described, using a superconducting analogy in which fermions coupled perturbatively to gravitons are in an unstable false vacuum. The coupling of the fermions to gravitons and a screened attractive interaction among pairs of fermions generates fermion condensates with zero momentum and a phase transition induces a non-perturbative transition to a true vacuum state. This produces a positive energy gap Δ in the vacuum energy identified with [Formula: see text] where Λ is the cosmological constant. In the strong coupling limit, a large cosmological constant induces a period of inflation in the early universe, followed by a weak coupling limit in which [Formula: see text] vanishes exponentially fast as the universe expands due to the dependence of the energy gap on the density of Fermi surface fermions, predicting a small cosmological constant in the early universe.

APA, Harvard, Vancouver, ISO, and other styles

14

Tyagi, P. K., and J. Dey. "Linear Instability of Laterally Strained Constant Pressure Boundary-Layer Flows." AIAA Journal 40, no. 9 (September 2002): 1916. http://dx.doi.org/10.2514/2.1874.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Tyagi, P. K., and J. Dey. "Linear Instability of Laterally Strained Constant Pressure Boundary-Layer Flows." AIAA Journal 39, no. 3 (March 2001): 526–27. http://dx.doi.org/10.2514/2.1338.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

El-Sayed, M. F. "Electrohydrodynamic Taylor-Helmholtz instability of a liquid with constant shear." Physica Scripta 55, no. 3 (March 1, 1997): 350–54. http://dx.doi.org/10.1088/0031-8949/55/3/014.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Tyagi, P. K., and J. Dey. "Linear instability of laterally strained constant pressure boundary-layer flows." AIAA Journal 39 (January 2001): 526–27. http://dx.doi.org/10.2514/3.14762.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Axenides, Minos, George Georgiou, and Zacharias Roupas. "Gravothermal instability with a cosmological constant in the canonical ensemble." Journal of Physics: Conference Series 410 (February 8, 2013): 012130. http://dx.doi.org/10.1088/1742-6596/410/1/012130.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Guo, Yan. "Instability of symmetric vortices with large charge and coupling constant." Communications on Pure and Applied Mathematics 49, no. 10 (October 1996): 1051–80. http://dx.doi.org/10.1002/(sici)1097-0312(199610)49:10<1051::aid-cpa2>3.0.co;2-d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Gadkari, P., and S. Ghosh. "Brillouin Instability in Longitudinally Magnetized Crystals with High Dielectric Constant." physica status solidi (b) 172, no. 2 (August 1, 1992): 709–18. http://dx.doi.org/10.1002/pssb.2221720222.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

SAKA, Masumi, Mikio MURAOKA, and Hiroyuki ABE. "Ductile instability of time-dependent crack growth under constant loading." Transactions of the Japan Society of Mechanical Engineers Series A 54, no. 497 (1988): 14–23. http://dx.doi.org/10.1299/kikaia.54.14.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Junaideen, Sainulabdeen Mohamed, Leslie George Tham, and Chack Fan Lee. "Instability of Compacted Residual Soil." Geosciences 11, no. 10 (September 24, 2021): 403. http://dx.doi.org/10.3390/geosciences11100403.

Full text

Abstract:

Static liquefaction of loose sands has been observed to initiate at stress ratios far less than the steady-state stress ratio. Different collapse surface concepts largely based on undrained triaxial test results have been proposed in the literature to explain the above instability phenomenon of loose sands. Studies of the instability behavior of fill material derived from residual soils remain limited. The present study investigated the instability behavior of a compacted residual soil using the conventional undrained triaxial tests and specially equipped constant shear triaxial tests. The test results were characterized in the p’: q: v space using the current state parameter with respect to the steady-state line for the residual soil. A modified collapse surface that has gradients varying with p’ and v was proposed for the loose residual soil to represent the instability states of undrained loading. Under constant shear stress conditions, the soil can mobilize stress ratios higher than those defined by the modified collapse surface. An instability surface was therefore presented for the instability states reached in static loading. Further, an alternative method of deducing the instability surface from the undrained stress paths was introduced.

APA, Harvard, Vancouver, ISO, and other styles

23

BIRTEA, PETRE. "INSTABILITY IN THE PRESENCE OF AN INDEFINITE CONSERVATION LAW." International Journal of Geometric Methods in Modern Physics 07, no. 03 (May 2010): 425–30. http://dx.doi.org/10.1142/s0219887810004373.

Full text

Abstract:

Consider a C1 vector field X on a finite-dimensional manifold M and xe an equilibrium point for the dynamics [Formula: see text]. We will prove that if I is a C2 constant of motion for X such that xe is also a critical point of I, then [Formula: see text] is a constant of motion for the linearized system [Formula: see text]. As a consequence we will give an instability result under the condition that [Formula: see text] is an indefinite quadratic form. If xe is not a critical point of I, then we obtain [Formula: see text] as a constant of motion for the linearized system.

APA, Harvard, Vancouver, ISO, and other styles

24

Capone, Florinda, Roberta De Luca, and Isabella Torcicollo. "Instability of Vertical Constant Through Flows in Binary Mixtures in Porous Media with Large Pores." Mathematical Problems in Engineering 2019 (February 12, 2019): 1–8. http://dx.doi.org/10.1155/2019/7379597.

Full text

Abstract:

A binary mixture saturating a horizontal porous layer, with large pores and uniformly heated from below, is considered. The instability of a vertical fluid motion (throughflow) when the layer is salted by one salt (either from above or from below) is analyzed. Ultimately boundedness of solutions is proved, via the existence of positively invariant and attractive sets (i.e. absorbing sets). The critical Rayleigh numbers at which steady or oscillatory instability occurs are recovered. Sufficient conditions guaranteeing that a secondary steady motion or a secondary oscillatory motion can be observed after the loss of stability are found. When the layer is salted from above, a condition guaranteeing the occurrence of “cold” instability is determined. Finally, the influence of the velocity module on the increasing/decreasing of the instability thresholds is investigated.

APA, Harvard, Vancouver, ISO, and other styles

25

Schilstra, M. J., P. M. Bayley, and S. R. Martin. "The effect of solution composition on microtubule dynamic instability." Biochemical Journal 277, no. 3 (August 1, 1991): 839–47. http://dx.doi.org/10.1042/bj2770839.

Full text

Abstract:

The exchange of tubulin dimer into steady-state microtubules was studied over a range of solution conditions, in order to assess the effects of various common buffer components on the dynamic instability of microtubules. In comparison with standard buffer conditions (100 mM-Pipes buffer, pH 6.5, containing 0.1 mM-EGTA, 1.8 mM-MgC12 and 1 M-glycerol), the rate and extent of exchange, and thus of dynamic instability, are suppressed by increasing the concentration of glycerol above 2 M. Exchange is enhanced by the addition of further Mg2+ (up to 17 mM) or by the addition of Ca2+ (up to 0.4 mM). Phosphate ion (150 mM) has relatively little effect on the dynamic behaviour of microtubules, as judged by the exchange method. The findings are interpreted within the framework of the Lateral Cap model for microtubule dynamic instability, in terms of the effects of these changes on the intrinsic rate constants of the system. By contrast, the extent of tubulin exchange depends selectively on the value of the dissociation rate constant for tubulin-GDP. A decrease in the extent of exchange, and hence in dynamic activity, is associated with a decreased value for this rate constant, and vice versa. The results also show good agreement of predictions of the model in treating the observed variations in the dynamic properties of individual microtubules, induced by different solution conditions.

APA, Harvard, Vancouver, ISO, and other styles

26

Li, Wei, Zhiwei Song, Xuexia Gao, and Zhigang Chen. "Dynamic Instability Analysis of a Rotating Ship Shaft under a Periodic Axial Force by Discrete Singular Convolution." Shock and Vibration 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/482607.

Full text

Abstract:

Dynamic instability of a rotating ship shaft subjected to a periodic axial force is studied by using discrete singular convolution (DSC) with regularized Shannon’s delta kernel. The excitation frequency is related to the spinning speed and the number of blades on the propeller. Effects of number of blades, constant term in the periodic force, and damping on dynamic instability regions are investigated. The results have shown that the increase of number of blades and damping could improve the dynamic stability of rotating shaft with damping. The increase of constant term in the periodic force leads to dynamic instability regions shifting to lower frequencies, making the shaft more sensitive to periodic force. Those dynamic instability regions obtained by DSC method have been compared with those by Floquet’s method to verify the application of DSC method to dynamic instability analysis of rotating ship shaft.

APA, Harvard, Vancouver, ISO, and other styles

27

Selke, David L. "A Classical Approach to Nuclear Instability." European Journal of Applied Physics 3, no. 5 (October 12, 2021): 45–46. http://dx.doi.org/10.24018/ejphysics.2021.3.5.109.

Full text

Abstract:

We extend a classical model of nuclei to include geometry as well as electron-like shells, then apply the model to the moments leading up to nuclear decay. The model leads to the well-known half-life or constant probability of a given nucleus to decay in a given time.

APA, Harvard, Vancouver, ISO, and other styles

28

Kuznetsov, V. D. "Magnetic Buoyancy with Viscosity and Ohmic Dissipation and Flux Tube Formation." Symposium - International Astronomical Union 142 (1990): 58–59. http://dx.doi.org/10.1017/s0074180900087726.

Full text

Abstract:

In the framework of the magnetohydrodynamic equations with dissipative terms in the form of turbulent viscosity (Vt) the linear stage of the instability of a subphotospheric field with respect to magnetic buoyancy is considered. For an exponential in z, isothermal plane-parallel atmosphere with a constant Alfvenic velocity the perturbations of the form are described by differential equation with constant coefficients. The qualitative dependence of the growth rate of instability on transverse wave number is determined (see Figures 1 and 2) and characteristic scales of the magnetic tubes are evaluated at the linear stage of instability (Kuznetsov, 1987, 1988).

APA, Harvard, Vancouver, ISO, and other styles

29

Nanua, P., and K. J. Waldron. "Instability and Chaos in Quadruped Gallop." Journal of Mechanical Design 116, no. 4 (December 1, 1994): 1096–101. http://dx.doi.org/10.1115/1.2919492.

Full text

Abstract:

A dynamic model for the two-dimensional quadruped has been developed. The main body is modelled as a rigid bar and each leg consists of a constant stiffness spring, a viscous damper and a force actuator. Based on symmetry principles, a controller has been devised that will enable the quadruped to gallop at constant speed. The controller consists of two parts: an energy controller which will apply the required amount of force through the legs, and the speed controller that will control the forward speed by appropriately placing the legs. It will be shown that the body pitch need not be explicitly controlled. The stability of this controller will be examined using Poincare maps. Stable systems show either periodic or quasi-periodic response. This system also exhibits chaotic behavior and chaotic response results in instability. The stability of the system with changes in the initial conditions, as well as variations in the system parameters, will also be examined. It will be shown that the system is stable for a range of leg stiffnesses. Outside this range, the system shows chaotic behavior.

APA, Harvard, Vancouver, ISO, and other styles

30

Joo, Y., and V. K. Dhir. "On the Mechanism of Fluidelastic Instability of a Tube Placed in an Array Subjected to Two-Phase Crossflow." Journal of Fluids Engineering 117, no. 4 (December 1, 1995): 706–12. http://dx.doi.org/10.1115/1.2817326.

Full text

Abstract:

In this work, the fluidelastic instability of a tube placed in an array subjected to two-phase crossflow has been studied. For the determination of fluidelastic instability, acrylic tubes 2.2 cm or 2.37 cm in diameter and 20 cm in length were arranged in a triangular array with pitch to diameter ratio of 1.4 and 1.3. The test tube was flexibly supported with two cantilever beams. By installing cantilever beams horizontally and vertically, drag and lift direction tube vibration were studied. The total damping ratio is found to increase as the liquid gap velocity or void fraction increases. It has been found that the effective spring constant decreases rapidly with increase of liquid gap velocity or void fraction just prior to the onset of instability. For the range of parameters studied in this work, the onset of fluidelastic instability is associated with a rapid decrease of the effective spring constant because for a given applied force the amplitude of the tube vibration is inversely proportional to the spring constant.

APA, Harvard, Vancouver, ISO, and other styles

31

Kerrebrock, J. L., and J. Kalamas. "Flow instability in plane-parallel particle beds with constant volumetric heating." Journal of Propulsion and Power 11, no. 5 (September 1995): 1028–35. http://dx.doi.org/10.2514/3.23933.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Binétruy, P., J. M. Cline, and C. Grojean. "Dynamical instability of brane solutions with a self-tuning cosmological constant." Physics Letters B 489, no. 3-4 (September 2000): 403–10. http://dx.doi.org/10.1016/s0370-2693(00)00932-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Midgley, T. L., G. A. Fox, G. V. Wilson, D. M. Heeren, E. J. Langendoen, and A. Simon. "Seepage-Induced Streambank Erosion and Instability: In Situ Constant-Head Experiments." Journal of Hydrologic Engineering 18, no. 10 (October 2013): 1200–1210. http://dx.doi.org/10.1061/(asce)he.1943-5584.0000685.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

SAIGO, Muneharu, and Takuzo IWATSUBO. "Instability of rotating system coupled by Constant Velocity joints (2nd report)." Transactions of the Japan Society of Mechanical Engineers Series C 52, no. 473 (1986): 258–63. http://dx.doi.org/10.1299/kikaic.52.258.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Fang, Kuo-Lung, and Bing-Yue Tsui. "Metal drift induced electrical instability of porous low dielectric constant film." Journal of Applied Physics 93, no. 9 (May 2003): 5546–50. http://dx.doi.org/10.1063/1.1563292.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Herbst, Ira, and Juliane Rama. "Instability of Pre-Existing Resonances Under a Small Constant Electric Field." Annales Henri Poincaré 16, no. 12 (December 16, 2014): 2783–835. http://dx.doi.org/10.1007/s00023-014-0389-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Liu, Feng, Jinsheng Lv, Bo Zhang, and Zhuqiang Yang. "Nonlinear stability analysis of Ledinegg instability under constant external driving force." Chemical Engineering Science 206 (October 2019): 432–45. http://dx.doi.org/10.1016/j.ces.2019.05.035.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Galkowski, Jeffrey. "Pseudospectra of semiclassical boundary value problems." Journal of the Institute of Mathematics of Jussieu 14, no. 2 (March 14, 2014): 405–49. http://dx.doi.org/10.1017/s1474748014000061.

Full text

Abstract:

AbstractWe consider operators$ - \Delta + X $, where$ X $is a constant vector field, in a bounded domain, and show spectral instability when the domain is expanded by scaling. More generally, we consider semiclassical elliptic boundary value problems which exhibit spectral instability for small values of the semiclassical parameter$h$, which should be thought of as the reciprocal of the Péclet constant. This instability is due to the presence of the boundary: just as in the case of$ - \Delta + X $, some of our operators are normal when considered on$\mathbb{R}^d$. We characterize the semiclassical pseudospectrum of such problems as well as the areas of concentration of quasimodes. As an application, we prove a result about exit times for diffusion processes in bounded domains. We also demonstrate instability for a class of spectrally stable nonlinear evolution problems that are associated with these elliptic operators.

APA, Harvard, Vancouver, ISO, and other styles

39

Koršunovs, Aleksandrs, Valters Vēciņš, and Vilnis Juris Turkovs. "Distance Sensor and Wheel Encoder Sensor Fusion Method for Gyroscope Calibration." Applied Computer Systems 26, no. 2 (December 1, 2021): 71–79. http://dx.doi.org/10.2478/acss-2021-0009.

Full text

Abstract:

Abstract MEMS gyroscopes are widely used as an alternative to the more expensive industrial IMUs. The instability of the lower cost MEMS gyroscopes creates a large demand for calibration algorithms. This paper provides an overview of existing calibration methods and describes the various types of errors found in gyroscope data. The proposed calibration method for gyroscope constants provides higher accuracy than datasheet constants. Furthermore, we show that using a different constant for each direction provides even higher accuracy.

APA, Harvard, Vancouver, ISO, and other styles

40

Hsu, H. C., C. Kharif, M. Abid, and Y. Y. Chen. "A nonlinear Schrödinger equation for gravity–capillary water waves on arbitrary depth with constant vorticity. Part 1." Journal of Fluid Mechanics 854 (September 3, 2018): 146–63. http://dx.doi.org/10.1017/jfm.2018.627.

Full text

Abstract:

A nonlinear Schrödinger equation for the envelope of two-dimensional gravity–capillary waves propagating at the free surface of a vertically sheared current of constant vorticity is derived. In this paper we extend to gravity–capillary wave trains the results of Thomas et al. (Phys. Fluids, 2012, 127102) and complete the stability analysis and stability diagram of Djordjevic & Redekopp (J. Fluid Mech., vol. 79, 1977, pp. 703–714) in the presence of vorticity. The vorticity effect on the modulational instability of weakly nonlinear gravity–capillary wave packets is investigated. It is shown that the vorticity modifies significantly the modulational instability of gravity–capillary wave trains, namely the growth rate and instability bandwidth. It is found that the rate of growth of modulational instability of short gravity waves influenced by surface tension behaves like pure gravity waves: (i) in infinite depth, the growth rate is reduced in the presence of positive vorticity and amplified in the presence of negative vorticity; (ii) in finite depth, it is reduced when the vorticity is positive and amplified and finally reduced when the vorticity is negative. The combined effect of vorticity and surface tension is to increase the rate of growth of modulational instability of short gravity waves influenced by surface tension, namely when the vorticity is negative. The rate of growth of modulational instability of capillary waves is amplified by negative vorticity and attenuated by positive vorticity. Stability diagrams are plotted and it is shown that they are significantly modified by the introduction of the vorticity.

APA, Harvard, Vancouver, ISO, and other styles

41

ZHU, DAVID Z., and GREGORY A. LAWRENCE. "Holmboe's instability in exchange flows." Journal of Fluid Mechanics 429 (February 25, 2001): 391–409. http://dx.doi.org/10.1017/s002211200000286x.

Full text

Abstract:

A laboratory study of the exchange of two fluids of different density through a constant-width channel with an underwater sill has enabled us to study Holmboe's instability in greater detail than has been possible in mixing-layer experiments. The internal hydraulics of the exchange flow are such that we have been able to observe the initiation of instability, the development and behaviour of both symmetric and asymmetric Holmboe instabilities, and the suppression of the instability at bulk Richardson numbers above about 0.7. A number of stability criteria resulting from previous numerical investigations have been verified experimentally. Our laboratory measurements are consistent with theoretical predictions of wave speed and wavenumber.

APA, Harvard, Vancouver, ISO, and other styles

42

Unger, R. Zackary, Jeremy M. Burnham, Lee Gammon, Chaitu S. Malempati, Cale A. Jacobs, and Eric C. Makhni. "The Responsiveness of Patient- Reported Outcome Tools in Shoulder Surgery Is Dependent on the Underlying Pathological Condition." American Journal of Sports Medicine 47, no. 1 (January 11, 2018): 241–47. http://dx.doi.org/10.1177/0363546517749213.

Full text

Abstract:

Background: Given the high number of available patient-reported outcome (PRO) tools for patients undergoing shoulder surgery, comparative information is necessary to determine the most relevant forms to incorporate into clinical practice. Purpose: To determine the utilization and responsiveness of common PRO tools in studies involving patients undergoing arthroscopic rotator cuff repair or operative management of glenohumeral instability. Study Design: Systematic review. Methods: A systematic review of rotator cuff and instability studies from multiple databases was performed according to PRISMA guidelines. Means and SDs of each PRO tool utilized, study sample sizes, and follow-up durations were collected. The responsiveness of each PRO tool compared with other PRO tools was determined by calculating the effect size and relative efficiency (RE). Results: After a full-text review of 238 rotator cuff articles and 110 instability articles, 81 studies and 29 studies met the criteria for final inclusion, respectively. In the rotator cuff studies, 25 different PRO tools were utilized. The most commonly utilized PRO tools were the Constant (50 studies), visual analog scale (VAS) for pain (44 studies), American Shoulder and Elbow Surgeons (ASES; 39 studies), University of California, Los Angeles (UCLA; 20 studies), and Disabilities of the Arm, Shoulder and Hand (DASH; 13 studies) scores. The ASES score was found to be more responsive than all scores including the Constant (RE, 1.94), VAS for pain (RE, 1.54), UCLA (RE, 1.46), and DASH (RE, 1.35) scores. In the instability studies, 16 different PRO tools were utilized. The most commonly used PRO tools were the ASES (13 studies), Rowe (10 studies), Western Ontario Shoulder Instability Index (WOSI; 8 studies), VAS for pain (7 studies), UCLA (7 studies), and Constant (6 studies) scores. The Rowe score was much more responsive than both the ASES (RE, 22.84) and the Constant (RE, 33.17) scores; however, the ASES score remained more responsive than the Constant (RE, 1.93), VAS for pain (RE, 1.75), and WOSI (RE, 0.97) scores. Conclusion: Despite being frequently used in the research community, the Constant score may be less clinically useful as it was less responsive. Additionally, it is a greater burden on the provider because it requires objective strength and range of motion data to be gathered by the clinician. In contrast, the ASES score was highly responsive after rotator cuff repair and requires only subjective patient input. Furthermore, separate PRO scoring methods appear to be necessary for patients undergoing rotator cuff repair and surgery for instability as the instability-specific Rowe score was much more responsive than the ASES score.

APA, Harvard, Vancouver, ISO, and other styles

43

Balan, Corneliu. "Pure Material Instability and the Concept of Yield Stress." Applied Rheology 9, no. 2 (April 1, 1999): 58–63. http://dx.doi.org/10.1515/arh-2009-0004.

Full text

Abstract:

Abstract The paper is concerned with the rheological study of gels, complex materials which are characterised by an internal network structure developed in viscous liquids. This category of materials exhibits in viscometric motion a yield state at a critical value of the applied shear stress. The yield shear stress defines the plateau behaviour in the steady flow curve. The creeping experiments and the dynamics of the Oldroyd’s 3 constants model put in evidence the connection between the loss of stability of the network structure and the coexisting strain rates at a constant shear stress. The correlation between theory, numerical simulations and experiments are established. All the results are qualitatively consistent with the statement that the concept of yield stress is ’natural defined‘ in the context of the pure material (structural) instability (i.e. instability at zero Reynolds number) of constitutive relations with non-monotone flow curve.

APA, Harvard, Vancouver, ISO, and other styles

44

López Hernández, Fernando A., and Román Mínguez Salidos. "The Scan-LM to Test Instability in the Constant Coefficient of Spatial Autoregressive Models." Economia 44, no. 87 (May 6, 2021): 74–88. http://dx.doi.org/10.18800/economia.202101.005.

Full text

Abstract:

This paper presents a test based on the principle of Lagrange Multipliers to identify spatial instability in the constant coefficient of regression models including substantive spatial dependence. The test has been adapted to the Scan methodology. Its main advantage is that it identifies areas with differential behavior without the need to provide information about their location, shape, or size. The study shows the utility of the test, reconsidering the results obtained by Mur et al.(2008) about instability in the distribution of per capita income in European regions.

APA, Harvard, Vancouver, ISO, and other styles

45

Coleman, Colin S. "Non-constant Superluminal Velocities in AGN." Publications of the Astronomical Society of Australia 8, no. 04 (1990): 353–56. http://dx.doi.org/10.1017/s1323358000023717.

Full text

Abstract:

AbstractLarge apparent superluminal velocities are observed in nuclear jets in Active Galaxies, indicating the presence of relativistic velocities almost along the line of sight. If the flow is well collimated, as suggested by the large scale radio structure, the inferred alignment leads to difficulties with source statistics. Here a modification of the usual relativistic beam model is proposed, in which the jet is assumed to contain azimuthal (swirling) flow. Perturbation analysis is used to show that the jet is unstable to a Kelvin-Helmholtz helical standing wave, the wavelength of which increases without bound in the limit of vanishing swirl. This instability may cause a cylindrical jet to follow a helical path in space, thereby reducing the implied alignment of a superluminal source, and providing a natural interpretation of non-constant superluminal velocities.

APA, Harvard, Vancouver, ISO, and other styles

46

Abdurraqeeb, Akram M., Abdullrahman A. Al-Shamma’a, Abdulaziz Alkuhayli, Abdullah M. Noman, and Khaled E. Addoweesh. "RST Digital Robust Control for DC/DC Buck Converter Feeding Constant Power Load." Mathematics 10, no. 10 (May 23, 2022): 1782. http://dx.doi.org/10.3390/math10101782.

Full text

Abstract:

The instability of DC microgrids is the most prominent problem that limits the expansion of their use, and one of the most important causes of instability is constant power load CPLs. In this paper, a robust RST digital feedback controller is proposed to overcome the instability issues caused by the negative-resistance effect of CPLs and to improve robustness against the perturbations of power load and input voltage fluctuations, as well as to achieve a good tracking performance. To develop the proposed controller, it is necessary to first identify the dynamic model of the DC/DC buck converter with CPL. Second, based on the pole placement and sensitivity function shaping technique, a controller is designed and applied to the buck converter system. Then, validation of the proposed controller using Matlab/Simulink was achieved. Finally, the experimental validation of the RST controller was performed on a DC/DC buck converter with CPL using a real-time Hardware-in-the-loop (HIL). The OPAL-RT OP4510 RCP/HIL and dSPACE DS1104 controller board are used to model the DC/DC buck converter and to implement the suggested RST controller, respectively. The simulation and HIL experimental results indicate that the suggested RST controller has high efficiency.

APA, Harvard, Vancouver, ISO, and other styles

47

Virányi, Zsanett, Antal Szommer, Ágota Tóth, and Dezső Horváth. "Lateral instability controlled by constant electric field in an acid-catalyzed reaction." Phys. Chem. Chem. Phys. 006, no. 13 (2004): 3396–401. http://dx.doi.org/10.1039/b402382j.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Guseinov, G. Sh, and I. Y. Karaca. "Instability intervals of a hill's equation with piecewise constant and alternating coefficient." Computers & Mathematics with Applications 47, no. 2-3 (January 2004): 319–26. http://dx.doi.org/10.1016/s0898-1221(04)90027-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Clough, T. M., A. Goel, and P. Hirst. "Patellar instability following total knee replacement — the dangers of constant design evolution." Knee 9, no. 2 (May 2002): 151–53. http://dx.doi.org/10.1016/s0968-0160(01)00141-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Almeida, Luis, Fabrice Bethuel, and Yan Guo. "A remark on the instability of symmetric vortices with large coupling constant." Communications on Pure and Applied Mathematics 50, no. 12 (December 1997): 1295–300. http://dx.doi.org/10.1002/(sici)1097-0312(199712)50:12<1295::aid-cpa5>3.0.co;2-3.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!