scholarly journals Pressure Wave Caused by Trinitrotoluene (TNT) Underwater Explosion—Short Review

2020 ◽  
Vol 10 (10) ◽  
pp. 3433
Author(s):  
Radosław Kiciński ◽  
Bogdan Szturomski
Keyword(s):  
Pressure Wave ◽  
Time Course ◽  
Underwater Explosion ◽  
Computer Hardware ◽  
Acoustic Medium ◽  
Computational Techniques ◽  
Pressure Waves ◽  
Underwater Explosions ◽  
Mesh Density ◽  
The Impact

The development of computational techniques and computer hardware has an impact the analysis of short-term (fast-changing) processes, such as the impact of a non-contact underwater explosion pressure waves. A theory of underwater explosions, gas bubble formation and pressure waves are presented. The course of the pressure wave in time, and its propagation in the acoustic medium are presented. The study presents empirical descriptions of non-contact pressure explosion waves. We propose to use them in simulations of ship hull strength and other objects immersed in liquids that are exposed to the effects of non-contact trinitrotoluene (TNT)-charge explosions. Pressure distributions and their time courses given by authors such as R.H. Cole, J.S. Nawagin, W. Stiepanow, T.E. Farley and H.G. Snay, T.L. Geers and K.S. Hunter are compared. A method of pressure wave modeling using acoustic media implemented in Computer Aided Engineering (CAE) programs is presented. The results of the values and the time course of the pressure acting on the underwater object are given. The influence of FEM (Finite Element Method) mesh density on the obtained results is examined and presented. The aim of the article is to expand our knowledge of underwater explosions, compare mathematical descriptions of the pressure waves developed by different authors and show the differences between them. In addition, we present the distinction between contact and non-contact explosions and analyze how changes in the mesh density of acoustic elements affects the reflection of the incident wave caused by an underwater explosion.

scholarly journals Pressure Wave Caused by Trinitrotoluene Underwater Explosion

2020 ◽  
Author(s):  
Radosław Kiciński
Keyword(s):  
Pressure Wave ◽  
Bubble Formation ◽  
Underwater Explosion ◽  
Computer Hardware ◽  
Acoustic Medium ◽  
Computational Techniques ◽  
Pressure Waves ◽  
Underwater Explosions ◽  
Explosion Pressure ◽  
The Impact

The development of computational techniques and computer hardware has an impact the analysis of short-term (fast-changing) processes, such as the impact of a non-contact underwater explosion pressure waves. A theory of underwater explosions, gas bubble formation and pressure waves are presented. The course of the pressure wave in time, and its propagation in the acoustic medium are presented. Entry presents empirical descriptions of non-contact pressure explosion waves. 

scholarly journals Simulation of the impact resistance of Kilo type submarine loaded with non-contact mine explosion

2017 ◽  
pp. 99-110
Author(s):  
Bogdan Szturomski ◽  
Radosław Kiciński
Keyword(s):  
Finite Element Method ◽  
Pressure Wave ◽  
Impact Resistance ◽  
Acoustic Medium ◽  
The Finite Element Method ◽  
State Of Stress ◽  
Stress And Deformation ◽  
Submarine Hull ◽  
Explosion Load ◽  
The Impact

The paper presents simulations of the state of stress and deformation of the Kilo class submarine hull loaded from pressure wave of non-contact mine explosion. To accomplish the task the finite element method was used. Pressure wave was described by T. L. Geers’a and K. S. Hunter model. The way of modeling the pressure wave using the acoustic medium implemented to CAE programs was shown. To describe the material an elastic-plastic model of Jonson-Cook which takes into account the speed of deformation was used. The paper presents pressure distribution on the Kilo type submarine hull exposed on 100 kg of TNT explosion load in front of the bow of the ship.

Characterization of the Pressure Wave Emitted From Implosion of Submerged Cylindrical Shell Structures

2012 ◽  
Author(s):  
Michael D. Shields ◽  
Pawel Woelke ◽  
Najib N. Abboud
Keyword(s):  
Pressure Wave ◽  
Pressure Pulse ◽  
Peak Pressure ◽  
Structural Parameters ◽  
Shell Structures ◽  
High Fidelity ◽  
Pressure Waves ◽  
Structural Configurations ◽  
The Impact

Buckling of submerged cylindrical shells is a sudden and rapid implosion which emits a high pressure pulse that may be damaging to nearby structures. The characteristics of this pressure pulse are dictated by various parameters defining the shell structure such as the length to diameter ratio, shell thickness, material, and the existence and configuration of internal stiffeners. This study examines, through the use of high fidelity coupled fluid-structure finite element computations, the impact of various structural parameters on the resulting pressure wave emanating from the implosion. The results demonstrate that certain structural configurations produce pressure waves with higher peak pressure and impulse thereby enhancing the potential for damage to nearby structures.

Transient Phenomena in Wave Propagation around a Large Suspended Particle in a Water-Filled Tube

2014 ◽  
Vol 566 ◽  
pp. 431-436
Author(s):  
Tatsuro Hori ◽  
Kazuaki Inaba ◽  
Kosuke Takahashi ◽  
Kikuo Kishimoto
Keyword(s):  
Pressure Wave ◽  
Suspended Particle ◽  
Free Fall ◽  
Stress Waves ◽  
Pressure Waves ◽  
Hoop Strain ◽  
Transient Phenomena ◽  
Elastic String ◽  
Particle Material ◽  
The Impact

Our study focuses on the response of a water-filled polycarbonate tube under axial impact loading to the presence of a single large suspended particle. The particles, composed of steel, aluminum, and polycarbonate, were individually suspended by elastic string along the centerline of the tube. The impact of a free-fall piston initiated pressure waves in the water, called water hammer, and stress waves in the tube, especially at the level of the particle. Hoop strains were measured as impact responses; their distribution indicated that the maximum strains occurred around the particle. These maximum strains are narrowly confined and independent of particle composition. From measurements, hoop strain above the level of the particle become larger with increasing particle mass. We propose a theoretical model that assumes the particle to be a rigid body, and estimate tube responses from the change in area due to the particle’s presence rather than a dependence on particle material. With similar conditions as in experiments, numerical simulations, performed using the software AUTODYN, revealed that the particle motion initiated a reflected pressure wave and created another pressure wave underneath the particle. The transients propagating around the particle are independent of particle material, but composition does affect the attenuation of the reflected pressure wave above the particle.

Decline of contractility during ischemia-reperfusion injury: actin glutathionylation and its effect on allosteric interaction with tropomyosin

2006 ◽  
Vol 290 (3) ◽  
pp. C719-C727 ◽  
Author(s):  
Frank C. Chen ◽  
Ozgur Ogut
Keyword(s):  
Reperfusion Injury ◽  
Posttranslational Modifications ◽  
Actin Polymerization ◽  
Time Course ◽  
Troponin I ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
High Concentration ◽  
Cross Sectional ◽  
The Impact

The severity and duration of ischemia-reperfusion injury is hypothesized to play an important role in the ability of the heart subsequently to recover contractility. Permeabilized trabeculae were prepared from a rat model of ischemia-reperfusion injury to examine the impact on force generation. Compared with the control perfused condition, the maximum force (Fmax) per cross-sectional area and the rate of tension redevelopment of Ca2+-activated trabeculae fell by 71% and 44%, respectively, during ischemia despite the availability of a high concentration of ATP. The reduction in Fmax with ischemia was accompanied by a decline in fiber stiffness, implying a drop in the absolute number of attached cross bridges. However, the declines during ischemia were largely recovered after reperfusion, leading to the hypothesis that intrinsic, reversible posttranslational modifications to proteins of the contractile filaments occur during ischemia-reperfusion injury. Examination of thin-filament proteins from ischemic or ischemia-reperfused hearts did not reveal proteolysis of troponin I or T. However, actin was found to be glutathionylated with ischemia. Light-scattering experiments demonstrated that glutathionylated G-actin did not polymerize as efficiently as native G-actin. Although tropomyosin accelerated the time course of native and glutathionylated G-actin polymerization, the polymerization of glutathionylated G-actin still lagged native G-actin at all concentrations of tropomyosin tested. Furthermore, cosedimentation experiments demonstrated that tropomyosin bound glutathionylated F-actin with significantly reduced cooperativity. Therefore, glutathionylated actin may be a novel contributor to the diverse set of posttranslational modifications that define the function of the contractile filaments during ischemia-reperfusion injury.

Abstract 160: Pim-1 Preserves Cardiac Stem Cell Proliferation with Age

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Michael McGregor ◽  
Shabana Din ◽  
Natalie Gude ◽  
Mark A Sussman
Keyword(s):  
Cell Proliferation ◽  
Stem Cell ◽  
Time Course ◽  
Protein A ◽  
Cell Types ◽  
Tissue Homeostasis ◽  
Dominant Negative ◽  
Repair Capacity ◽  
Tissue Samples ◽  
The Impact

Rationale Cardiac stem cells (CSC) regulate cardiomyogenesis and support regenerative processes in the heart, but aging adversely affects stem cell repair capacity. Aging is a primary cause of impaired cardiac function characterized by accumulation of senescent cells. CSC senescence is associated with permanent growth arrest that decreases survival signaling and cellular replacement, inevitably diminishing the capacity of the heart to maintain tissue homeostasis. Therefore, promoting CSC growth may improve cardiac performance with age. Pim-1 kinase exhibits protective and proliferative effects in the myocardium but the role of Pim-1 in cardiac aging has not been thoroughly studied. Objective Demonstrate that Pim-1 promotes stem cell growth in the aged myocardium correlating with increased expression of centromere protein A (CENP-A), a kinetochore-associated protein known to support cell proliferation in numerous species and cell types. Methods & Results CENP-A expression levels were evaluated from murine myocardial tissue samples ranging in age from 11 days post coitum to 4 months of age with analysis by immunoblot as well as quantitative PCR. CENP-A expression was colocalized with c-kit as a marker of CSC by immunohistochemical labeling, revealing a decline in CENP-A expression over the time course of postnatal myocardial maturation. The impact of Pim-1 upon CENP-A level was assessed by comparative analysis of non-transgenic mice versus genetically modified transgenic mouse lines expressing either Pim-1 (wild type) or a dominant negative functionally dead Pim-1 mutant. Pim-1 overexpression increases persistence of CENP-A in CSCs with age, as well as the prevalence of cycling CSCs as marked by phosph-H3 expression, while the functionally dead mutant accelerates CENP-A diminution and decreases CSC proliferation. Conclusion CENP-A decline in c-kit positive cells with age provides intriguing evidence of a potential mechanism for the diminished capacity of CSCs to maintain tissue homeostasis. Pim-1 mitigates CENP-A diminution, demonstrating the promising potential of Pim-1 to promote cardiac growth and repair with age.

scholarly journals Lack of Obvious Influence of PLLA Nanofibers on the Gene Expression of BMP-2 and VEGF during Growth and Differentiation of Human Mesenchymal Stem Cells

2009 ◽  
Vol 9 ◽  
pp. 313-319 ◽  
Author(s):  
Markus D. Schofer ◽  
S. Fuchs-Winkelmann ◽  
C. Wack ◽  
M. Rudisile ◽  
R. Dersch ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Factor ◽  
Time Course ◽  
Negative Impact ◽  
Fracture Repair ◽  
Bone Morphogenetic Protein 2 ◽  
Vegf Gene ◽  
Down Regulation ◽  
Artificial Graft ◽  
The Impact

Growth factors like bone morphogenetic protein 2 (BMP-2) and vascular endothelial growth factor (VEGF) play an important role in bone remodeling and fracture repair. Therefore, with respect to tissue engineering, an artificial graft should have no negative impact on the expression of these factors. In this context, the aim of this study was to analyze the impact of poly(L-lactic acid) (PLLA) nanofibers on VEGF and BMP-2 gene expression during the time course of human mesenchymal stem cell (hMSC) differentiation towards osteoblasts. PLLA matrices were seeded with hMSCs and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of VEGF and BMP-2. Furthermore, BMP-2–enwoven PLLA nanofibers were used in order to elucidate whether initial down-regulation of growth factor expression could be compensated. Although there was a great interpatient variability with respect to the expression of VEGF and BMP-2, PLLA nanofibers tend to result in a down-regulation in BMP-2 expression during the early phase of cultivation. This effect was diminished in the case of VEGF gene expression. The initial down-regulation was overcome when BMP-2 was directly incorporated into the PLLA nanofibers by electrospinning. Furthermore, the incorporation of BMP-2 into the PLLA nanofibers resulted in an increase in VEGF gene expression. Summarized, the results indicate that the PLLA nanofibers have little effect on growth factor production. An enhancement in gene expression of BMP-2 and VEGF can be achieved by an incorporation of BMP-2 into the PLLA nanofibers.

A model for the relation between respiratory neural and mechanical outputs. III. Validation

1981 ◽  
Vol 51 (4) ◽  
pp. 990-1001 ◽  
Author(s):  
M. Younes ◽  
W. Riddle ◽  
J. Polacheck
Keyword(s):  
Respiratory System ◽  
Pressure Wave ◽  
Time Course ◽  
Present Report ◽  
Occlusion Pressure ◽  
Single Breath ◽  
Wave Forms ◽  
Inspiratory Activity ◽  
Good Agreement

In the preceding two communications we described a model for the relation between respiratory neural and mechanical outputs. In the present report we test the accuracy of the model in predicting volume and flow from occlusion pressure wave forms, and vice versa. We performed single-breath airway occlusions in 21 unconscious subjects and determined the time course of occlusion pressure. We also measured the passive properties of the respiratory system. The time course of volume and flow was predicted from the occlusion pressure wave forms, and the results were compared with the spontaneous breaths immediately preceding occlusion. Inspiratory duration, shape and amplitude of occlusion-pressure wave forms, and the passive properties of the respiratory system varied widely among subjects. There was good agreement between predicted and observed values in all cases. Except for some prolongation of inspiration (Hering-Breuer reflex), diaphragmatic activity did not change during occlusion. Since occlusion pressure is proportional to inspiratory activity, we conclude that the model described provides a good approximation of the relation between inspiratory activity and spirometric output.

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