Drop Distance Research Articles

Spreading and Deposit Characteristics of a Rapid Dry Granular Avalanche Across 3D Topography: Experimental Study

Aiming to understand the propagation and deposit behaviours of a granular avalanche along a 3D complex basal terrain, a new 3D experimental platform in 1/400 scale was developed according to the natural terrain of the Xiejiadianzi rock avalanche, with a series of laboratory experiments being conducted. Through the conduction of these tests, parameters, including the morphological evolution of sliding mass, run-outs and velocities of surficial particles, thickness contour and centre of final deposit, equivalent frictional coefficient, and energy dissipation, are documented and analysed, with the geomorphic control effect, material grain size effect, drop angle effect, and drop distance effect on rock avalanche mobility being discussed primarily. From the study, some interesting conclusions for a better understanding of rock avalanche along a 3D complex basal topography are reached. (1) For the granular avalanche tested in this study, great differences between the evolutions of the debris along the right and left branch valleys were observed, with an obvious geomorphic control effect on avalanche mobility presented. In addition, some other interesting features, including groove-like trough and superelevation, were also observed under the control of the topographic interferences. (2) The equivalent frictional coefficients of the granular avalanches tested here range from 0.48 to 0.57, which is lower than that reached with a set-up composed of an inclined chute and horizontal plate and higher than that reached using a set-up composed of only an inclined chute. And the higher the drop angle and fine particle content, the higher the equivalent frictional coefficient. The effect of drop distance on avalanche mobility is minor. (3) For a granular avalanche, momentum transfer plays an important role in the motion of mass, which can accelerate the mobility of the front part greatly through delivering the kinetic energy of the rear part to the front.

Abstract 2186: Incorporation of natural compounds into biomaterials to prevent breast cancer recurrence

Abstract Numerous studies have demonstrated that naturally occurring phytochemicals such as Tannic acid (TA) possess anti-cancer properties. Apoptotic activity is increased in breast cancer and prostate cancer cells in response to exposure to tannin extracts. Collagen type I is a biomaterial routinely used for cosmetic and reconstructive surgeries, including breast reconstruction following breast cancer mandated surgeries. TA functions as a collagen crosslinking agent through both hydrogen bonding and hydrophobic effects. Thus, if TA-crosslinked collagen type I is used for breast reconstruction procedures, the crosslinked collagen will be remodeled by growing breast epithelial cells and adipocytes where the incorporated TA will be released killing nearby residual cancer cells preventing recurrence. When adipocytes are grown on TA-crosslinked collagen beads the measureable released TA induces caspase-mediated apoptosis in ER+ and HER2+ breast cancer cells but has no effect on triple negative breast cancer cells and reduced apoptotic-inducing activity in normal breast epithelial cells. We are developing an injectable matrix comprised of TA-crosslinked collagen beads and adipocytes to serve as a tissue regeneration platform in patients post-lumpectomy. Variables such as collagen temperature, syringe pump rate, and drop distance have been studied to determine ideal method for producing beads of the desired size and shape. These promising results will lead to the construction of a matrix designed to not only promote tissue regeneration but also simultaneously help to prevent tumor recurrence. This matrix provides protection in breast cancer patients and holds promise for patients suffering from other soft tissue cancers. Citation Format: Lauren Jordan, Bailey-Jean Walker, Christopher Moody, Brian W. Booth. Incorporation of natural compounds into biomaterials to prevent breast cancer recurrence. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2186.

P‐Wave Attenuation with Implications for Earthquake Early Warning

Several widely implemented and tested earthquake early warning algorithms employ empirical equations that relate earthquake magnitudes with ground‐motion peak amplitudes and hypocentral distances. This approach is effective to the extent that the offline dataset available for setting the fitting coefficients in those equations is of sufficient quality and quantity. However, to address the problem of having a limited dataset, it is instructive to gain physical understanding of the main factors controlling the P ‐wave attenuation. In this study, theoretical expressions are derived that relate the root mean square (rms) of the P ‐wave displacement d rms and velocity v rms to the seismic moment, stress drop, and hypocentral distance. The theoretical attenuation laws are then validated against observed attenuation, using earthquake data from southern California and Japan. Good agreement is found between observed and predicted ground motions. The similar ground‐motion attenuation in California and Japan suggests that the attenuation laws are similarly applicable for the two regions and implies that they may also be implemented in other regions without having to go through a lengthy calibration phase. Because d rms is more strongly dependent on the seismic moment than v rms, use of the attenuation law for d rms yields better magnitude prediction than that of v rms. It is shown that the d rms‐to‐ v rms ratio is proportional to the characteristic length of the rupture and that the stress drop is a function of the seismic moment and the cube of d rms/ v rms. This result paves the way for a new stress‐drop determination scheme that is totally independent of previously used approaches. Finally, it is shown that the rms of the ground motions are proportional to their peak values.

Assessment of lateral subluxation in Legg-Calvé-Perthes disease: a time-sequential study of magnetic resonance imaging and plain radiography.

Lateral subluxation of the femoral head is one of the poor prognostic factors of Legg-Calvé-Perthes disease. The aim of this study was to investigate the cause of lateral subluxation of the femoral head on the basis of the changes over time on MRI. Twenty-four patients with unilateral Legg-Calvé-Perthes disease were analyzed retrospectively. Lateral subluxation was measured as the tear drop distance on radiographs. We focused on joint fluid, medial articular cartilage thickening, and abnormal lesion on MRI. Lateral subluxation continued significantly in patients with poor results. Among the MRI findings, the presence of an abnormal lesion was associated significantly with the continuous lateral subluxation.

On the critical thickness and wavelength of a condensing thin liquid film in a binary vapor mixture system

We study the linear stability of a condensing thin liquid film of a binary vapor mixture by solving directly the bulk equations of the gas phase. The boundary layer of a finite thickness is introduced above the liquid film, within which the variables are disturbed. The dynamics of the liquid film is described by the long-wave equation. The neutral stability condition predicts the existence of a critical thickness below which a flat film is stable due to the mass gain effect. However, if we consider the thickening of the liquid film by condensation, the relative neutral stability can be defined such that the growth rate of a disturbance is equal to that of the basic film thickness. The critical thickness and wavenumber obtained from the relative neutral stability condition significantly change from the original ones. Employing the asymptotic analysis for large wavenumbers, the critical thickness and wavelength are numerically calculated for the water–ethanol system. Their dependence on the boundary layer thickness, temperature and ambient vapor concentration is investigated. The critical wavelength obtained from our theory has the same trend in the temperature and concentration as the initial drop distance observed in the experiment.

MP7-17 DIFFERENTIAL DETECTION OF LESIONS ON MULTI-PARAMETRIC PROSTATE MRI WITH OR WITHOUT USE OF AN ENDORECTAL COIL BASED ON QUANTITATIVE MEASURES OF OBESITY

INTRODUCTION AND OBJECTIVES: Multiparametric 3T MRI (MP-MRI) with the use of an endorectal coil (ERC) provides improved signal to noise ratio for evaluation of prostatic lesions suspicious for prostate cancer. Herein, we aim to determine the degree of lesion identification lost by eliminating the use of an ERC based upon measures of obesity. METHODS: Prospectively collected data on 20 patients on an active surveillance protocol at the National Cancer Institute who have undergone non-ERC MP-MRI in 2013 following a prior ERC MP-MRI were analyzed. MP-MRI prostatic lesions suspicious for prostate cancer were identified and recorded on both ERC and non-ERC studies for each patient. Patient demographics including age, PSA, BMI, abdominal girth, waist circumference, and the drop distance from the anterior abdominal wall to the anterior aspect of the prostate were recorded. Quantitative measures of obesity were measured on T2-weighted MRI sequences. These parameters were analyzed using univariate and multivariable linear regression models individually with age and PSA to assess for significance in the decrease in number of lesions identified on followup studies without ERC use. RESULTS: The average number of lesions identified on ERC MP-MRI and followup non-ERC MP-MRI was 1.4 0.9 and 0.5 0.7, respectively. On univariate analysis, age and PSA were not significantly associated with a decrease in the number of lesions identified when the ERC was not used on followup MP-MRI. Of the quantitative parameters of obesity, on univariate analysis, greater BMI (p1⁄40.01) and abdominal girth (p1⁄40.0097) were significantly associated with a larger differential in the number of lesions identified. On multivariable linear regression models incorporating each of the measures of obesity with age and PSA, BMI (p1⁄40.026) and abdominal girth (p1⁄40.019) remained significant independent predictors of the difference in numbers of lesions identified between ERC and non-ERC studies. CONCLUSIONS: Typically more intraprostatic lesions are identified by MP-MRI performed with ERC due to the optimized signal to noise ratio. This difference is more dramatic in obese patients where the distance between body and surface coils and the prostate gland are increased. BMI and abdominal girth are predictors of significantly lower lesion identification when ERC is eliminated from the MP-MRI study. Since obesity has a negative impact on the detection of prostate cancer with non-ERC MRI, ERC use may be most important in this patient population.

Factors Affecting Urea Granulation Tower Simplification of Ventilation

Currently, most of the domestic fertilizer unit, granulation tower basically using natural ventilation, granulation tower granulation process is ejected molten urine through the nozzle to cool down after melt crystallization (phase transition), cooling 3 process[1]. The beginning step is cooling stage of liquid urea. The second step is liquid urea into solid urea particles. The last step is solid urea paticles cooling process with long drop distance. In the process of landing urea crystals, the releasing heat is taken into the cold air. The average air rate of natural ventilation in the tower is 0.4-0.8m/s. And the air rate of mechanical ventilation prilling tower is 0.6-1.2m/s. Landing time of urea particles from nozzle to Scraper is about 5-10m/s.

Research of the Dynamic Compaction Effective Reinforcement Depth of Cohesionless Soil

The effective reinforcement depth is one of the most important parameters of dynamic compaction method design and construction, so far it is still lack of in-depth theoretical study. In this paper, combined with the field test, FLAC3D was used to do the numerical simulation of dynamic compaction reinforcement to cohesionless soil. By the simulation, this paper analyzed the factors which may influence the effective reinforcement depth, such as the hammers weight, drop distance, base area, and the soil parameters. The orthogonal design method was used to analyze the soil parameters sensitivity to the effective reinforcement depth. Combined with the results of numerical analysis and the traditional empirical formulae, the effective reinforcement depth calculation formula was established for cohesionless soil. Engineering verification shows that, the results estimated by the formula is reliable, and can provide certain reference for the future engineering.

Influence of solvent and drop distance on the formation of ENR/PVC/silica aerogel beads

The influence of solvent properties and drop distance were investigated in the preparation of silica-filled epoxidised natural rubber/polyvinyl chloride (ENR/PVC) aerogel beads. The formation of these composite beads was done by dropping polymer solution into a solidifying solution via phase inversion/solvent exchange. The beads were collected and finally dried at 80°C in ambient pressure. FTIR spectroscopy, optical microscopy, and scanning electron microscopy (SEM) were carried out to characterise the samples. Infrared spectroscopy analysis of the composite showed the presence of Si-O-Si and Si-OH bonds as well as hydrogen bonding between organic and inorganic components which enhance compatibility between them. The morphological studies showed a high homogeneity of silica dispersion within the ENR/PVC matrix. Solidifying solution of the 50% v/v water/ethanol was found to be suitable for formation of spherical droplets of ENR/PVC/silica due to the polarity and surface tension of the solution. The height of dropping was also found to have significantly affected the formation of beads by which 20 cm was determined to be the optimum height. Under the established conditions, the mean diameter of the spherical beads was in the range of 2.0-2.5 mm.

Testing Study and Numerical Analysis of Dynamic Compaction on the Red Sandstone Rubble Soil

The drop distance, times of dynamic compaction and other parameters are studied by on-site testing in order to analyse quantitatively the impact on effective reinforcement depth and radius of the red sandstone rubble soil. Large amounts of on-site test data shows that compactness standard is 93%, strong encryption range is 1.0～4.0m, the effective impact depth is 4～6m and the effective impact radius is 2.5～3.5m. At the same time, through comparison and verification the on-site testing data and numerical analysis, the relationship between times of dynamic compacting and sandstones subside is . Further more, it is revealed that dynamic compaction can restrain effectively the deformation of high fill embankment of the red sandstone rubble soil.

Characteristics of condensate drop movement with application of bulk surface temperature gradient in Marangoni dropwise condensation

The characteristics of the spontaneous movement of condensate drops when a bulk temperature gradient is applied to a horizontal condensing surface in Marangoni dropwise condensation of a water−ethanol vapor mixture were experimentally investigated over a wide range of bulk temperature gradients and for various mass fractions. Drops were observed to move from the low-temperature side to the high-temperature side of the heat transfer surface. When the initial drop distance was adopted as a parameter for the Marangoni force acting on the condensate drop together with the surface tension gradient corresponding to the surface temperature of the condensing surface, the drop velocity was highly correlated with both the surface tension gradient and the initial drop distance over a wide range of parameters. At relatively large initial drop distances, the condensate drop velocity increases as the initial drop distance is reduced and it subsequently decreases after the velocity reaches its maximum value under an almost constant bulk surface tension gradient. The drop velocity increases linearly with increasing bulk surface tension gradient for a constant initial drop distance.

A study of solid particle flow characterization in solar particle receiver

The solid particle receiver (SPR) is a direct absorption receiver in which solar energy heats a curtain of falling ceramic particle to a temperature in excess of 1000 °C. A small scale test platform was built to investigate particle flow properties. The curtain was comprised of approximately 697 μm ceramic particles that were dropped within the receiver cavity of the test platform. Tests were conducted to experimentally determine the distribution of particles velocity, curtain thickness, and curtain opacity along a drop length of approximately 3 m. Velocity data were measured using a high speed digital camera to obtain images of the particle flow at 1000 frames per second with an exposure time of 100 μs. Five mass flow rates ranging from 1 kg/s-m to 22 kg/s-m were examined, and it was found that all flows approached a terminal velocity of about 6–7 m/s in a vertical drop distance of 3 m. The experimental results were validated with computational results and were found in excellent agreement with the simulation results. In addition, a similar study was performed with various sizes of the particles to better understand how the particle flow characteristics were affected by the size of the particles.

Hip and Knee Extensor Moments Predict Vertical Jump Height in Adolescent Girls

Biomechanical factors, such as hip and knee extensor moments, related to drop jump (DJ) performance have not been investigated in adolescent girls. The purpose of this study was to determine the key independent biomechanical variables that predict overall vertical jump performance in adolescent girls. Sixteen high school adolescent girls from club-sponsored and high school-sponsored volleyball teams performed DJ at 3 different drop heights (15, 30, and 45 cm). A motion analysis system consisting of 10 digital cameras and a force platform was used to calculate vertical jump height, joint angles, and joint moments during the tasks. A multiple linear regression was used to determine the biomechanical parameters that were best predictive of vertical jump height at each box drop distance. The 2 predictor variables in all 3 models were knee and hip extensor moments. The models predicted 82.9, 81.9, and 88% of the vertical jump height variance in the 15, 30, and 45 cm trials, respectively. The results of the investigation indicate that knee and hip joint moments are the main contributors to vertical jump height during the DJ in adolescent girls. Strength and conditioning specialists attempting to improve vertical jump performance should target power and strength training to the hip and knee extensors in their athletes.

Shock membrane electropotential drops and limited diffusive distance of β-amyloids in cerebral neurons are detrimental enhancement to Alzheimer's diseases

Molecular physicobiochemical calculations indicated that the metallic ion binding to beta-amyloids (Aβ) may induce production of hydrogen peroxide, which triggers the Ca ion redistribution from the extracellular to the intracellular compartmentation, resulting in a transient membrane electropotential drop by at least 208.06 mV. Moreover, using the Mark and Houwink empirical equation, we predicted that the diffusible distances of all Aβ identities would be confined in a very tiny region within a radius less than 3.96 × 10 −4 cm in brain at 192 h after produced. Because of the inherent tendency of aggregation behaved by the Aβs, the maximum diffusion coefficient and inherent viscosity were 8.24 × 10 −15 cm 2 s −1 and 72.15 cps for the 12 mers (40.8 kDa), the largest soluble form of ABs. Conclusively, we have quantitatively predicted that the shock membrane potential drop (Δ φ > 208.06 mV) and limited diffusible distance (<3.96 × 10 −4 cm) in the brain would contribute the major detrimental effects to the neurons in the Alzheimer's diseases.

マランゴニ凝縮における伝熱面温度勾配下の表面張力差液滴移動 : 初生液滴間隔の影響(熱工学,内燃機関,動力など)

マランゴニ凝縮における伝熱面温度勾配下の表面張力差液滴移動 : 初生液滴間隔の影響(熱工学,内燃機関,動力など)

Directed Aerial Descent Behavior in African Canopy Ants (Hymenoptera: Formicidae)

Several species of neotropical ants direct their aerial descent toward tree trunks during a fall from the forest canopy. The primary goal of this study was to determine if afrotropical arboreal ants exhibit similar gliding behavior. Ants were collected from nine tree crowns in late secondary forest at a hydrocarbon extraction site near Gamba, Gabon. Of the 32 species tested, the behavior was observed in five Cataulacus spp. and three Camponotus spp., making this the first report of gliding in African ants. Aerial glide performance (horizontal distance traveled per unit vertical drop distance) decreased with increasing body size among species and among individuals of Cataulacus erinaceus. Characteristics of directed descent behavior in C. erinaceous were very similar to those of the neotropical ant Cephalotes atratus.

Thermal accelerometer based predictive drop sensor

The thermal accelerometer measures internal changes in heat transfer caused by acceleration. It has been the most reliable sensor employed for hard disk drive (HDD) drop protection system because this kind of device is capable to survive high shocks. The frequency response is limited to 17Hz, however, so that protection functions only when the drop distance exceeds 17cm, considering the HDD park time being 70ms. At this drop height, the impact force shock of up to 246.6g could happen without any sensing signal which will trigger the protection function into operation. The HDD could thus be damaged since the allowable shock g rating in operation mode is only 200g/1ms. Based on the transient response modeling of the thermal accelerometer, a predictive filter was developed to predict the drop by proprietary algorithms. The predictive drop sensor, composed of a commercial thermal accelerometer and micro controller chip, can achieve fast response as it alarms impending fall and enables the protection function before real drop occurs. By the optimization of the filter weighting coefficients, accurate prediction of the impending drop event has been shown in this study. Predictions of up to 35ms have been demonstrated and that can provide reliable protection against drop shock.

Effects of Gender on Landing Mechanics in an Unanticipated Landing Task in Children

PURPOSE: To investigate lower-extremity biomechanical differences between preadolescent boys and girls when performing a drop-landing. The landing task incorporated a visual cue provided just prior to ground contact directing the subjects to run in one of three possible directions after landing. METHODS: Forty-four subjects (20 males & 24 females) were recruited from a local youth soccer league to participate in this study. In this preliminary analysis, data from five females (mean age = 10.8 yrs, mean mass = 37.19 kg, mean ht. = 1.45 m) and five males (mean age = 11.4yrs, mean mass = 33.82 kg, mean ht. = 1.43 m) were examined. Three dimensional lower limb kinematics were recorded at 250 Hz using a commercial motion capture system. Subjects hung with both hands from a horizontal bar (mean drop distance = 30.5 cm) and on a verbal command released their grip and dropped onto one leg landing on one of two floor mounted force plates (landing leg determined before trial commenced). Upon landing, subjects were instructed to run as fast as possible to one of three floor mounted targets placed 3.66 m in front of the landing area. Run direction was unanticipated (UA) since subjects did not know until after bar release which one of the three targets would illuminate. The targets were located directly ahead of the landing area, 30° to the left, and 30° to the right. Three trials were collected for each direction for each landing leg, resulting in straight ahead, sidestepping, and crossover trials with the order of trials randomized for each leg (18 trials/subject). In this preliminary analysis, data from left leg landings with a sidestep to the right were analyzed for coronal, sagittal, and transverse plane kinematics at the hip, knee and ankle at the time of initial contact (IC) with the ground. Differences between boys and girls were assessed for each variable using a Student's t-Test. RESULTS: Our preliminary analysis found no significant kinematic differences at the hip and ankle between boys and girls at IC. However, a significant difference between boys and girls was found for knee flexion angle at IC (p <0.04) with girls landing with less flexion than boys. No difference was found on knee valgus or rotation, and no other significant kinematic differences were found. CONCLUSIONS: Our results conflict with recent research that found differences in knee valgus but not in knee flexion at IC in middle and high school aged athletes who performed an unanticipated cutting maneuver. These preliminary results indicate that differences in landing mechanics between genders may exist prior to pubescence.

Dynamics of shallow impact cratering

We present data for the time dependence of wooden spheres penetrating into a loose noncohesive packing of glass beads. The stopping time is a factor of 3 longer than the time d/v0 needed to travel the total penetration distance d at the impact speed v0. The acceleration decreases monotonically throughout the impact. These kinematics are modeled by a position- and velocity-dependent stopping force that is constrained to reproduce prior observations for the scaling of the penetration depth with the total drop distance.

Penetration depth for shallow impact cratering

We present data for the penetration of a variety of spheres, dropped from rest, into a loose noncohesive granular medium. We improve upon earlier work [J. S. Uehara, Phys. Rev. Lett. 90, 194301 (2003)] in three regards. First, we explore the behavior vs sphere diameter and density more systematically, by holding one of these parameters constant while varying the other. Second, we prepare the granular medium more reproducibly and, third, we measure the penetration depth more accurately. The new data support the previous conclusion that the penetration depth is proportional to the 1/2 power of sphere density, the 2/3 power of sphere diameter, and the 1/3 power of total drop distance.