An Approximate Procedure for the Solution of a Class of Transient-Wave Diffraction Problems

1966 ◽  
Vol 33 (1) ◽  
pp. 168-172 ◽  
Author(s):  
L. A. Peralta ◽  
G. F. Carrier ◽  
C. C. Mow
Keyword(s):  
Harmonic Wave ◽  
Elastic Solid ◽  
The Other ◽  
Wave Problem ◽  
Transient Wave ◽  
Harmonic Response ◽  
Elastic Systems ◽  
Computational Difficulty ◽  
Approximate Procedure ◽  
Potential Use

The description of even the gross features of the response to an incident stress pulse of an infinite elastic solid with a hole or obstruction requires very extensive calculations [1]. On the other hand, the response of such elastic systems to a harmonic incident wave is much less intricate. It is well known that the response to any given incident pulse can be constructed from the solution of the harmonic wave problem. Furthermore, it is clear that the computational difficulty associated with this synthesis can be reduced enormously when a suitable, algebraically simple approximation to the harmonic response can be found. In this paper, a useful rule for choosing the appropriate approximation to the harmonic wave response is presented. This method is shown to give results in agreement with known solutions. The procedure is also applied to problems where only solutions to the harmonic wave case are available. The most important potential use of the technique lies in the possibility that, for some classes of structures, one may be able to identify the parameters of the approximate harmonic response with simple macroscopic properties of the system. Such an identification would not only save much labor but would also identify design criteria for the optimization of the system.

Hemodialysis during cardiopulmonary resuscitation in patients with severe metabolic acidosis

2018 ◽  
Vol 41 (8) ◽  
pp. 431-436 ◽  
Author(s):  
Tuncay Sahutoglu ◽  
Elif Sahutoglu
Keyword(s):  
Metabolic Acidosis ◽  
Cardiopulmonary Resuscitation ◽  
High Efficiency ◽  
Spontaneous Circulation ◽  
The Other ◽  
Unresolved Issue ◽  
Severe Metabolic Acidosis ◽  
Hospital Records ◽  
Return Of Spontaneous Circulation ◽  
Potential Use

Background/Aims: Severe metabolic acidosis during cardiopulmonary resuscitation is an important and yet unresolved issue. The potential use of hemodialysis for severe metabolic acidosis during cardiopulmonary resuscitation was investigated. Methods: Acute hemodialyses between January 2012 and April 2017 were reviewed for patients with concomitant hemodialysis and cardiopulmonary resuscitation. In addition, MEDLINE was searched for similar reports. Data were extracted from hospital records. Results: Two patients (36M, 70F) were found to study, without similar reports in MEDLINE. Cardiac arrests (in-hospital) occurred due to severe metabolic acidosis in both patients (due to ethylene glycol and metformin intoxications, respectively). Return of spontaneous circulation could not be obtained within the first 28 and 30 min of cardiopulmonary resuscitation only, whereas both patients had return of spontaneous circulation following at least 45 min of concomitant hemodialysis and cardiopulmonary resuscitation. One patient (70F) was discharged with good neurological outcome, but the other died. Conclusion: The addition of high-efficiency hemodialysis during cardiopulmonary resuscitation may contribute to the return of spontaneous circulation in patients with severe metabolic acidosis due to intoxication.

scholarly journals Current Therapeutic Approaches in Metastatic and Recurrent Ewing Sarcoma

Sarcoma ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Michael Huang ◽  
Kenneth Lucas
Keyword(s):  
Ewing Sarcoma ◽  
Survival Rates ◽  
Salvage Chemotherapy ◽  
Common Type ◽  
The Other ◽  
Therapeutic Approaches ◽  
Primary Bone ◽  
Children And Young Adults ◽  
Improvement In Survival ◽  
Potential Use

Ewing sarcoma (ES) is the second most common type of primary bone malignancy in children and young adults. Survival rates for localized ES have improved to upwards of 70% with aggressive chemotherapy and local control. On the other hand, there has been little improvement in survival rates for patients with metastatic or recurrent ES. Herein we review the different current therapeutic approaches available, including the different upfront and salvage chemotherapy regimens, the role for stem cell transplantation, and potential use of immunotherapy.

A Variational Approach to the Dynamics of Structures Having Mixed or Discontinuous Boundary Conditions

1984 ◽  
Vol 51 (4) ◽  
pp. 831-836 ◽  
Author(s):  
P. J. Torvik
Keyword(s):  
Boundary Conditions ◽  
Variational Approach ◽  
Natural Frequencies ◽  
Elastic Solid ◽  
Approximate Solutions ◽  
Forced Response ◽  
Field Equations ◽  
Elastic Circular Plate ◽  
Discontinuous Boundary ◽  
Elastic Systems

A procedure is developed whereby the steady-state forced response and the modes of free vibration for elastic systems having mixed or discontinuous boundary conditions can be determined. Approximate solutions are obtained as a superposition of a set of functions, each of which satisfies the field equations but not the boundary conditions. The coefficients of this expansion are obtained through applying a variational principle developed from Hamilton’s principle which for simple harmonic motion, is equivalent to Reissner’s principle. The reduction from the general elastic solid to the elastic plate is given, as are some results obtained for the first several natural frequencies of an elastic circular plate, free on a portion of the boundary and clamped on the remainder.

scholarly journals Generalized Photo-Thermo-Microstretch Elastic Solid Semiconductor Medium Due To Excitation Process

2021 ◽  
Author(s):  
kh. lotfy ◽  
A. El-Bary
Keyword(s):  
Mechanical Load ◽  
Harmonic Wave ◽  
Plane Waves ◽  
Elastic Solid ◽  
Two Dimensions ◽  
Load Force ◽  
Normal Displacement ◽  
Physical Fields ◽  
Novel Model ◽  
Coupled Stress

Abstract A novel model in the theory of photo-thermoelasticity with microstretch properties is studied. The plasma-elastic-thermal plane waves are propagated in a linear isotropic generalized photo-thermo-microstretch elastic semiconductor solid medium. The photothermal excitation occurs in the context of the microinertia of microelement process during two dimensions (2D) deformation. The harmonic wave techniques are used to get the solutions for the basic variables. The analytical solution of the main physical fields; carrier intensity, normal displacement components, temperature, stress load force, microstress and tangential coupled stress can be obtained. Some graphics illustrated when using the plasma, thermal and mechanical load boundary conditions, which they apply at the outer free surface of the elastic medium. Some semiconductor materials as silicon (Si) and Germanium (Ge) are used to make the numerical simulation and some comparisons in different thermal memories are made. The main physical variables with new parameters are discussed theoretically and shown graphically.

scholarly journals The dynamical stresses produced in a thick plate by the action of surface forces

1958 ◽  
Vol 3 (4) ◽  
pp. 153-163 ◽  
Author(s):  
J. Fulton ◽  
I. N. Sneddon
Keyword(s):  
Thick Plate ◽  
Harmonic Wave ◽  
The Other ◽  
Two Dimensional ◽  
Direction Parallel ◽  
Free Surfaces ◽  
Phase Velocities ◽  
Medial Plane ◽  
Distribution Of Stress ◽  
Propagation Of Elastic Waves

The first discussion of the propagation of elastic waves in a thick plate was given by Lamb [1] for the two-dimensional problem of a harmonic wave travelling in a direction parallel to the medial plane of the plate. Lamb derived equations relating the thickness of the plate to the phase velocities of two types of wave, one symmetric with respect to the medial plane and the other antisymmetric. The symmetric modes of propagation introduced by Lamb have been studied by Holden [2] and the antisymmetric modes have been studied by Osborne and Hart [3]. More recently Pursey [4] has shown how the amplitude of the disturbance is related to a given distribution of stress, varying harmonically with time, applied to the free surfaces of the plate; two types of source are considered by Pursey, one producing a two-dimensional field of the Lamb type, and the other having circular symmetry about an axis normal to the surface of the plate.

Transient Wave Propagation in a Harmonically Heterogeneous Elastic Solid

1992 ◽  
Vol 59 (2S) ◽  
pp. S145-S151
Author(s):  
Hyun-Sil Kim ◽  
Jerry H. Ginsberg
Keyword(s):  
Floquet Theory ◽  
Elastic Solid ◽  
Harmonic Excitation ◽  
Additional Insight ◽  
Regular Perturbation ◽  
Transient Wave ◽  
One Dimensional ◽  
Dilatational Wave ◽  
Transient Wave Propagation ◽  
Insight Into

Transient propagation of a one-dimensional dilatational wave in a harmonically heterogeneous elastic solid is studied by several techniques. A regular perturbation analysis in terms of the characteristics of the differential equation shows that initiation of a temporally harmonic excitation that generates a signal whose wavelength is twice the periodicity of the heterogeneity leads to secularity in the first approximation. The frequency at which this situation occurs matches the frequency at which Floquet theory predicts that steady-state waves may be unstable. A finite difference algorithm based on integrating along the characteristics is developed and implemented to obtain a numerical solution. In the critical case, backscattering of the wave from the heterogeneity results in a mixture of propagating and standing wave features. However, rather than being unstable, the heterogeneity in this condition is shown to result in maximum interference with forward propagation. A comparable analysis for a step excitation on the boundary provides additional insight into the underlying propagation phenomena.

scholarly journals Liquid-liquid equilibria in solutions with potential ecological importance

2010 ◽  
Vol 75 (8) ◽  
pp. 1161-11165
Author(s):  
Zoran Visak
Keyword(s):  
Ionic Liquids ◽  
Liquid Phase ◽  
Practical Importance ◽  
The Other ◽  
Green Solvents ◽  
Poly Ethylene Glycol ◽  
Ecological Importance ◽  
Poly Ethylene ◽  
Ecologically Sustainable ◽  
Potential Use

In the last three years, our research follows two main issues, defined by the slogans: ?Green Meets Toxic? and ?Green Meets Green?. The first issue considers the potential use of ambient friendly solvents for toxic organic compounds of industrial and practical importance. The other is related to liquid phase behavior in solutions of ecologically sustainable substances. The ?Green? solvents studied are: ionic liquids, liquid poly(ethylene glycol), glycerol and 1,2 and 1,3-propanediol.

scholarly journals Evaluation of EPS Application in Microbial Consortia Growing in Aqueous Co-Contaminated Systems: The Trend to Natural Attenuation

2008 ◽  
Vol 2 (1) ◽  
pp. 176-182 ◽  
Author(s):  
P.S.O. Martins ◽  
N.F. Almeida ◽  
R.G.S. Costa ◽  
A.P. Franco ◽  
M.F. Vieira ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Natural Attenuation ◽  
Carbon Sources ◽  
Inhibitory Effect ◽  
Aqueous System ◽  
The Other ◽  
Microbial Consortia ◽  
Low Concentrations ◽  
Negative Effect ◽  
Potential Use

The needing of a bacterial extracellular polymeric substance (EPS) application in bioremediation of an aqueous system containing glucose and/or gasoline and/or heavy metals (Cd2+, Zn2+ and Cu2+) by two different microbial consortia was studied. At the low concentrations (1.00 ppm of each metal), it was observed an inhibitory effect on the metabolism of the “consortium 1”, as well as the application of EPS has improved the cellular growing in media containing glucose and/or gasoline as carbon sources, indicating that using this substance decreases the negative effect caused by the presence of heavy metals. In the other hand, the application of small concentrations of EPS was evaluated, and results show that a little increase in this substance concentration leads to an improvement of 39 % in cellular growing of the “consortium 2”, indicating the potential use of the EPS in a system with gasoline and metals. Once many microorganisms can produce this kind of substance during cultivation, our results show that a system with low concentrations of hydrocarbons and metals could be susceptible to natural attenuation, without human intervention in the environment, especially if the process is conducted in a larger period of time.

Reduction of the Distortion Current Factor of the Current Drawn by the Electromagnetic Vibrators Supplied at Variable Frequency

2012 ◽  
Vol 721 ◽  
pp. 275-280 ◽  
Author(s):  
Horia Balan ◽  
M.I. Buzdugan ◽  
C. Chiorean ◽  
P. Karaissas
Keyword(s):  
Electromagnetic Interference ◽  
Experimental Validation ◽  
Power Grid ◽  
The Other ◽  
Variable Frequency ◽  
Distortion Factor ◽  
Harmonic Response ◽  
Harmonic Content ◽  
Variable Element ◽  
Harmonic Measurement

The paper presents a possibility of supplying the electromagnetic vibrators with variable frequency voltage. Two types of modulated controls of the inverter’s commutation angle are presented. The theoretical analysis allows the study of the variable element influence on the distortion factor and of the harmonic content generated by the vibrator. The authors present an experimental validation of the presented theory, using the harmonic measurement of the distorted waveform. The harmonic response is useful in quantifying the performances of the harmonic filters to be introduced between the nonlinear consumer and the power grid and on the other hand the electromagnetic interference determined to other customers connected to the power grid.

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