Combination Of Penetration Research Articles

Experimental and numerical study on micro-blasting process of 3A dental implant titanium alloy: A comparison between finite element method and smoothed particle hydrodynamics

In the present study, solid particle erosion due to micro-blasting of dental implants (3A) made of titanium alloy under the impact of multiple alumina particles with an average diameter of 85 μm was analyzed, experimentally and numerically. The numerical investigation was conducted using finite element (FE) and smoothed particle hydrodynamics (SPH) methods. The erosive behavior of this alloy was simulated as impacts in micro-scale based on Johnson-Cook constitutive equations. By focusing on the particles impacts, a representative volume element (RVE) technique was proposed to simulate the arbitrary multiple particle impacts. The results of FE and SPH models are validated and compared with the experimental results. The effects of particle velocity and impact angle on the erosion rate of the alloy are then investigated. Finally, an equation is presented for prediction of the erosion rate versus velocity and angle of impact. The results indicate that for all impact velocities, the combination of penetration and cutting can create a critical condition of erosion damage for the titanium alloy.

Penetration and relaxation behavior of dry lunar regolith simulants

A return to the lunar surface has been identified as an important near-term goal for NASA and other international space agencies. Along with recent and upcoming missions to asteroid bodies and other extraterrestrial surfaces, this demands a comprehensive understanding of the mechanical properties of the regolith we are likely to encounter. Historically, penetrometers have been used to garner information about the near-surface, but in situ measurements give correlational data at best. To extend the usefulness of penetrometer measurements and provide more information about the regolith properties, we conducted laboratory penetration and subsequent relaxation measurements of two regolith simulants, one angular and cohesive and the other rounded and noncohesive, using a mechanical conical probe specially-designed to allow bulk sample relaxation. We measured penetration resistance and load-relaxation behavior for both simulants under constant displacement rate penetration at pressures ranging from 1E−5 Torr to 700 Torr and at relative densities of ~20% and ~80%. Penetration resistance was sensitive to density and insensitive to test pressure and simulant type. Relaxation was sensitive to all three conditions, and certain elastic parameters of a best-fit mechanical relaxation model can be used to differentiate between simulants, sample density, and test pressure. A combination of penetration and relaxation data may therefore be used to explore these properties in a field setting, and the relaxation behavior can also be tentatively correlated to more fundamental soil mechanics properties such as shear moduli. Furthermore, penetration/relaxation tests into sieved samples (coarse- and fine-grained versions of the simulants) show that penetration resistance can be used to determine relative particle size with respect to conical probe diameter and relaxation behavior indicates that a combination of fine- and coarse-grain particles produces a more cohesive behavior (in a mildly cohesive simulant) than either the fine- or coarse-grained counterparts. Additional testing in varying simulants and at more extreme ranges of temperature, pressure, density, and water ice content is suggested to refine these measurements, along with field testing to determine the viability of the use of this technology terrestrially as well as on future planetary missions.

Shear Shock Waves Observed in the Brain

The internal deformation of the brain is far more complex than the rigid motion of the skull. An ultrasound imaging technique that we have developed has a combination of penetration, frame-rate, and motion detection accuracy required to directly observe, for the first time, the formation and evolution of shear shock waves in the brain. Experiments at low impacts on the traumatic brain injury scale demonstrate that they are spontaneously generated and propagate within the porcine brain. Compared to the initially smooth impact, the acceleration at the shock front is amplified up to a factor of 8.5. This highly localized increase in acceleration suggests that shear shock waves are a fundamental mechanism for traumatic injuries in soft tissue.

Findings of Abnormal Videofluoroscopic Swallowing Study Identified by High-Resolution Manometry Parameters

ObjectiveTo identify the parameters of high-resolution manometry (HRM) with a significant correlation to abnormal findings of videofluoroscopic swallowing study (VFSS). DesignProspective study. SettingHospital rehabilitation department. ParticipantsPatients with dysphagia symptoms (N=40). InterventionParticipants were evaluated once using VFSS in neutral head position and evaluated twice using HRM with 5mL of thin fluid. Main Outcome MeasuresHRM parameters included maximal pressure, area integral, rise time, duration of the velopharynx and tongue base, maximal pressure of pre–upper esophageal sphincter (UES), low pharynx, cricopharyngeus, minimal UES pressure, UES activity time, and nadir UES duration. HRM parameters were compared with the findings of VFSS. Receiver operating characteristic analysis was performed to obtain the cutoff value, sensitivity, and specificity of HRM parameters for the prediction of findings of VFSS. ResultsThe maximum pressure of the velopharynx showed a significantly positive prediction for most abnormal parameters of VFSS in the pharyngeal phase. Nadir UES pressure duration was significant for impaired laryngeal elevation, residue at pyriformis sinus, and combination of penetration and aspiration. The maximum pressure of the velopharynx <180.0 showed 100% sensitivity and 75% specificity for the presence of penetration and aspiration, and the cutoff point of 178.8 showed 86.7% sensitivity and 75% specificity for the presence of subglottic aspiration. ConclusionsThis study identified significant HRM parameters that are highly specific for individual abnormalities of VFSS, suggesting the cutoff value, sensitivity, and specificity. Because HRM could inform the quantitative measurement of pharyngeal weakness, the cutoff value for HRM parameters could be used to predict aspiration in patients with pharyngeal weakness.

A Plea for the Introduction of Performance Related Bitumen Specifications

ABSTRACT The standard for bituminous binders EN 12591 uses the empirical property penetration as the basis of the grading system. We will show that a large variation in physical properties can be expected depending only on the combination of penetration and softening point within a single grade. It is inherent that this can affect asphalt properties. We present a number of graphs in which bitumen properties are correlated. The graphs show that crude oil source plays an important role. Some bitumens derived from specific crude oils do not comply with EN 12591 requirements. The performance grading system (PG) developed from the Strategic Highway Research Program (SHRP) focusses on performance at high as well as low service temperatures. Bitumen consistency and temperature susceptiblity are the properties that determine compliance with the requirements of a particular performance grade.

Method to Predict Temperature Susceptibility of an Asphalt Binder

It has been indicated that the dynamic modulus for hot-mix asphalt will be included as a means of material characterization in the forthcoming \IAASHTO 2002 Guide for Design of Pavement Structures\N as well as the Superpave performance prediction system. One candidate model being considered for predicting the dynamic modulus includes an input for binder viscosity. In this model, the temperature susceptibility of the binder can be characterized using two parameters—viscosity-temperature susceptibility (VTS) and A (intercept). A simple method, given here to predict the parameters for a binder based on conventional test results, would allow the practicing engineer to derive the VTS and A parameters given any combination of penetration and viscosity tests for the respective binder. The first part of this method includes a derivation of a mechanistic-empirical method for predicting the viscosity of a binder as a function of the penetration value. The second part includes a least-squares method by which the user can enter their laboratory data to calculate the VTS and A parameters for the binder.

Why Brands Grow

ABSTRACT What causes brands to grow over time? The article addresses this important question. Measures of market share, market penetration, customer loyalty, and price were gathered in two time periods, five years apart, for 353 brands in 21 categories of fast-moving consumer goods. We used these data to study share growth over time. Key findings include: (1) growth must be earned, even for brands that have been successful in the past; (2) increased penetration is the key to share growth, and especially dramatic share growth, for all types of brands; and (3) customer loyalty strongly leverages the effects of penetration. This paper extends upon work by Baldinger and Rubinson (1997) in demonstrating that the way to grow brands is via a combination of penetration and loyalty growth.

The interaction of bacterial lipopolysaccharide with phospholipid bilayers and monolayers

The association of bacterial lipopolysaccharide with artificial membranes was studied in an attempt to understand the mechanism of binding of lipopolysaccharide to cell surfaces and to look for an effect on membrane stability. The membrane models used were phospholipid bilayers and monolayers. As measured by survival time, lipopolysaccharide was found to decrease the stability of bilayers at a concentration of 300 μg/ml. When assayed by dielectric breakdown, an effect of lipopolysaccharide was noticeable at concentrations of 50 μg/ml. In studies involving the penetration of monomolecular films of various phospholipids, native and alkali-treated lipopolysaccharide both caused increases in surface pressure, and therefore penetrated the films. However, alkali-treated lipopolysaccharide was at least ten times more efficient than the native product in penetration. Alkali-treated lipopolysaccharide had a greater degree of surface activity than native lipopolysaccharide, since alkali-treated lipopolysaccharide formed monomolecular films by itself, whereas native lipopolysaccharide did not. The changes in the surface pressure and surface potential of phospholipid films produced by lipopolysaccharide in the subsolution suggested that the interaction of lipopolysaccharide with phospholipid monolayers was by a combination of penetration and adsorption to the undersurface.