scholarly journals The Recognition of the Micro-Events in Cement Composites and the Identification of the Destruction Process Using Acoustic Emission and Sound Spectrum

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2988 ◽  
Author(s):  
Dominik Logoń ◽  
Krzysztof Schabowicz
Keyword(s):  
Acoustic Emission ◽  
Three Dimensional ◽  
Sound Intensity ◽  
High Volume ◽  
Cement Composites ◽  
Destruction Process ◽  
Critical Crack ◽  
Additional Information ◽  
Sound Spectrum ◽  
Structure Destruction

This paper presents the recognition of micro-events and their concentration in quasi-brittle cement composites and the identification of the destruction process based on acoustic emission and sound spectrum. The tests were conducted on a quasi-brittle composite of a cement paste reinforced with a high volume of dispersed polypropylene fibers. The possibility of identifying the destruction process based on acoustic emission and sound spectrum was confirmed. This paper focused on the identification of micro-events using the 3D spectrum. It was shown that the identification of the concentration of micro-events precedes the occurrence of critical crack fcr, ending the Hooke’s law range. The ability to recognize this phenomenon with the use of the 3D spectrum makes it possible to predict the structure destruction process and subsequently to assess the structure destruction (micro and macro-cracks) and the reinforcement destruction (pull-off, breaking). It was confirmed that the three-dimensional spectrum provided additional information, enabling a better recognition of micro and macro-changes in the structure of the samples based on the analysis of sound intensity, amplitudes, and frequencies.

scholarly journals Identification of the Destruction Process in Quasi Brittle Concrete with Dispersed Fibers Based on Acoustic Emission and Sound Spectrum

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2266 ◽  
Author(s):  
Dominik Logoń
Keyword(s):  
Acoustic Emission ◽  
Three Dimensional ◽  
Sound Intensity ◽  
Destruction Process ◽  
Ordinary Concrete ◽  
Additional Information ◽  
Dimensional Spectrum ◽  
Sound Spectrum ◽  
Brittle Composites ◽  
Brittle Composite

The paper presents the identification of the destruction process in a quasi-brittle composite based on acoustic emission and the sound spectrum. The tests were conducted on a quasi-brittle composite. The sample was made from ordinary concrete with dispersed polypropylene fibers. The possibility of identifying the destruction process based on the acoustic emission and sound spectrum was confirmed and the ability to identify the destruction process was demonstrated. It was noted that in order to recognize the failure mechanisms accurately, it is necessary to first identify them separately. Three- and two-dimensional spectra were used to identify the destruction process. The three-dimensional spectrum provides additional information, enabling a better recognition of changes in the structure of the samples on the basis of the analysis of sound intensity, amplitudes, and frequencies. The paper shows the possibility of constructing quasi-brittle composites to limit the risk of catastrophic destruction processes and the possibility of identifying those processes with the use of acoustic emission at different stages of destruction.

scholarly journals Identifying the Range of Micro-Events Preceding the Critical Point in the Destruction Process in Traditional and Quasi-Brittle Cement Composites with the Use of a Sound Spectrum

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1809
Author(s):  
Dominik Logoń ◽  
Janusz Juraszek ◽  
Zbynek Keršner ◽  
Petr Frantík
Keyword(s):  
Critical Point ◽  
Stress Level ◽  
Compression Strength ◽  
Test Cases ◽  
Cement Composites ◽  
Test Results ◽  
Destruction Process ◽  
Four Point Bending ◽  
Sound Spectrum ◽  
Brittle Composites

This paper presents the possibilities of determining the range of stresses preceding the critical destruction process in cement composites with the use of micro-events identified by means of a sound spectrum. The presented test results refer to the earlier papers in which micro-events (destruction processes) were identified but without determining the stress level of their occurrence. This paper indicates a correlation of 2/3 of the stress level corresponding to the elastic range with the occurrence of micro-events in traditional and quasi-brittle composites. Tests were carried out on beams (with and without reinforcement) subjected to four-point bending. In summary, it is suggested that the conclusions can be extended to other test cases (e.g., compression strength), which should be confirmed by the appropriate tests. The paper also indicates a need for further research to identify micro-events. The correct recognition of micro-events is important for the safety and durability of traditional and quasi-brittle cement composites.

scholarly journals 3D visualization in otosurgery

2020 ◽  
Vol 19 (6) ◽  
pp. 38-49
Author(s):  
D. M. Kuz’min ◽  
◽  
A. A. Fedotova ◽  
Keyword(s):  
Middle Ear ◽  
3D Visualization ◽  
Research Work ◽  
Three Dimensional ◽  
Middle Ear Surgery ◽  
Ear Surgery ◽  
Task Load ◽  
Additional Information ◽  
Surgical Field ◽  
Nasa Task Load Index

The main priority of middle ear surgery is to create a safe and optimal view of the surgical field, as well as the most accurate visualization of anatomical structures, which is a driving factor in the evolution of otosurgery. The additional information provided by three-dimensional (3D) images has been proven to improve understanding of the temporal bone anatomy and improve the operator’s ability to assess associated diseases, thereby optimizing surgical management. In the presented experimental research work, a new technique for visualizing the surgical field is described, which improves the quality of the operator’s work and expands the possibilities of middle ear surgery. On the basis of the Chair of Otorhinolaryngology of the Mechnikov North-Western State Medical University a remote adapter for an endoscopic tube was created, which allows you to broadcast the video image received from its distal end to virtual reality glasses. For a detailed understanding of the principle of information transmission in a new three-dimensional reality, we used concepts such as disparity and stereopsis. All research results were evaluated according to the NASA Task Load Index scale. Analyzing the results of the experiment, in the conditions of three-dimensional visualization of the surgical field, a lower level of subjective workload was revealed, which was regarded as a positive effect of the realization of the phenomenon of stereopsis, when performing manipulations on the middle ear.

scholarly journals Climatological Features of the Weakly and Very Stably Stratified Nocturnal Boundary Layers. Part I: State Variables Containing Information about Regime Occupation

2019 ◽  
Vol 76 (11) ◽  
pp. 3455-3484 ◽  
Author(s):  
Carsten Abraham ◽  
Adam H. Monahan
Keyword(s):  
Wind Speed ◽  
Turbulence Intensity ◽  
Three Dimensional ◽  
Static Stability ◽  
Wind Component ◽  
State Variables ◽  
Intermittent Turbulence ◽  
Additional Information ◽  
State Variable ◽  
Mean Wind Speed

Abstract The atmospheric nocturnal stable boundary layer (SBL) can be classified into two distinct regimes: the weakly SBL (wSBL) with sustained turbulence and the very SBL (vSBL) with weak and intermittent turbulence. A hidden Markov model (HMM) analysis of the three-dimensional state-variable space of Reynolds-averaged mean dry static stability, mean wind speed, and wind speed shear is used to classify the SBL into these two regimes at nine different tower sites, in order to study long-term regime occupation and transition statistics. Both Reynolds-averaged mean data and measures of turbulence intensity (eddy variances) are separated in a physically meaningful way. In particular, fluctuations of the vertical wind component are found to be much smaller in the vSBL than in the wSBL. HMM analyses of these data using more than two SBL regimes do not result in robust results across measurement locations. To identify which meteorological state variables carry the information about regime occupation, the HMM analyses are repeated using different state-variable subsets. Reynolds-averaged measures of turbulence intensity (such as turbulence kinetic energy) at any observed altitude hold almost the same information as the original set, without adding any additional information. In contrast, both stratification and shear depend on surface information to capture regime transitions accurately. Use of information only in the bottom 10 m of the atmosphere is sufficient for HMM analyses to capture important information about regime occupation and transition statistics. It follows that the commonly measured 10-m wind speed is potentially a good indicator of regime occupation.

Micro-fiber reinforced cement composites. II. Flexural response and fracture studies

1995 ◽  
Vol 22 (4) ◽  
pp. 668-682
Author(s):  
N. Banthia ◽  
J. Sheng
Keyword(s):  
Crack Opening ◽  
Fiber Reinforcement ◽  
High Volume ◽  
Flexural Behavior ◽  
Cement Composites ◽  
Fiber Reinforced ◽  
Host Matrix ◽  
Flexural Response ◽  
Reinforced Cement ◽  
Resistance Curves

In Part I of this paper, stress–strain curves for micro-fiber reinforced cement-based composites containing high volume fractions of carbon, steel, and polypropylene fibers were obtained. Considerable strengthening, toughening, and stiffening of the host matrix due to micro-fiber reinforcement under both static and impact conditions were reported. In this paper, composites are characterized under an applied flexural load. Both notched and unnotched specimens were tested in four-point flexure; significant improvements in the flexural behavior due to fiber reinforcement were noted. Notched specimens were tested to study the growth of cracks in these composites and to develop a valid fracture criterion. With this objective, crack growth resistance curves and crack opening resistance curves in terms of the stress intensity factor were constructed. The paper recognizes the potential of these composites in various applications and stresses the need for further research. Key words: Portland cement-based materials, fiber reinforcement, fracture toughness, R-curves.

Numerical Simulation of the Kinetic Energy Projectile Oblique Penetration into the Concrete

2014 ◽  
Vol 989-994 ◽  
pp. 982-985
Author(s):  
Jun Chen ◽  
Xiao Jun Ye
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Kinetic Energy ◽  
Three Dimensional ◽  
Test Results ◽  
Destruction Process ◽  
3D Finite Element ◽  
Finite Element Software ◽  
Simulation Results ◽  
Target Characteristics

ANSYS-LS/DYNA 3D finite element software projectile penetrating concrete target three-dimensional numerical simulation , has been the target characteristics and destroy ballistic missile trajectory , velocity and acceleration and analyze penetration and the time between relationship , compared with the test results , the phenomenon is consistent with the simulation results. The results show that : the destruction process finite element software can better demonstrate concrete tests revealed the phenomenon can not be observed , estimated penetration depth and direction of the oblique penetration missile deflection .

Abstract 11808: Association Between Left Ventricular Properties in Patients With Hypertension and the Incidence of Paroxysmal Atrial Fibrillation: Three-Dimensional Speckle Tracking Echocardiographic Study

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Masafumi Kawade ◽  
Masanori Kawasaki ◽  
Shingo Minatoguchi ◽  
Ryuhei Tanaka ◽  
Maya Ishiguro ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Three Dimensional ◽  
High Volume ◽  
Left Ventricular ◽  
Myocardial Stiffness ◽  
3 Dimensional ◽  
Concentric Hypertrophy ◽  
Pulmonary Capillary ◽  
Echocardiographic Study ◽  
Heat Failure

Background: Hypertension (HTN) is one of the major causes of atrial fibrillation (AF), since it is usually accompanied by left atrial (LA) remodeling due to pressure and/or volume (LAV) overload. We examined the relationship between ventricular (LV) geometry or LV properties in HTN and the incidence of paroxysmal AF (PAF) using novel, one-beat, automated, 3-dimensional speckle tacking echocardiography (3D-STE) with high volume rates. Methods: Patients with HTN (n=107, age 69±7) and controls (n=60, age 69±9) were prospectively enrolled. HTN patients were divided into 5 groups according to LV geometry and the presence of hypertensive heat failure (HHF) {normal geometry (n=25), concentric remodeling (n=20), concentric hypertrophy (LVH) (n=24), eccentric LVH (n=21) and HHF (n=17)}. Isovolumic relaxation time (IVRT) was measured by Doppler echo. We evaluated LV ejection fraction (EF), E/e’, pulmonary capillary wedge pressure (PCWP), Tau, LV diastolic stress, LV strain and LV myocardial stiffness in sinus rhythm. PCWP was estimated as 10.7- 12.4 x log (LA active emptying function / minimum LAV) as we reported. Tau was calculated as IVRT / (ln 0.9 x systolic blood pressure - ln PCWP). LV diastolic stress was calculated as LV radius at end diastole x PCWP / thickness. LV strain rate (SR) during IVR, as an index of relaxation, and LV strain were measured by the 3D-STE with volume rates of 50-80vps. LV myocardial stiffness was estimated as LV stress / LV strain. Results: LVEF was reduced only in HHF compared with controls (56±7 vs. 67±6%). Conclusion: LVEF in HHF was decreased but still remained within the normal range, whereas diastolic properties in eccentric LVH and HHF were reduced compared with control. The incidence of PAF significantly increased in eccentric LVH and HHF associated with the impairment of LV relaxation and stiffness and increased LV stress. This suggests that the target of treatment to reduce the incidence of PAF in HTN must be diastolic function.

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