Velocity

This paper presents the results of ground vibration measurements carried out in Hisarcik Boron open pit mine located on the west side of central Anatolia near Kütahya province in Turkey. Within the scope of this study to predict peak particle velocity (PPV) level for this site, ground vibration components were measured for 304 shots during bench blasting. In blasting operations, ANFO (blasting agent), gelatin dynamite (priming), and delay electric detonators (firing) were used as explosives. Parameters of scaled distance (charge quantity per delay and the distance between the source and the station) were recorded carefully and the ground vibration components were measured for all blast events using two different types of vibration monitors (one White Mini-Seis and one Instantel Minimate Plus Model). The absolute distances between shot points and monitor stations were determined using GPS. The equation of square root scaled distance extensively used in the literature was taken into consideration for the prediction of PPV. Then, the data pairs of scaled distance and particle velocity obtained from the 565 event records were analyzed statistically. At the end of statistical evaluation of the data pairs, an empirical relation which gives 50% prediction line with a reasonable correlation coefficient was established between PPV and scaled distance.

Knowledge of the in‐situ sound velocity of drilling mud can be used in mud‐pulse acoustic telemetry for evaluating the presence and amount of gas invasion in the drilling mud. We propose a model for calculating the in‐situ density and sound velocity of water‐based and oil‐based drilling muds containing formation gas. Drilling muds are modeled as a suspension of clay particles and high‐gravity solids in water or oil, with the acoustic properties of these fluids depending on pressure and temperature. Since mud at different depths experiences different pressures and temperatures, downhole mud weights can be significantly different from those measured at the surface. Taking this fact into consideration, we assume constant clay composition and obtained the fraction of high‐gravity solids to balance the formation pressure corresponding to a given drilling plan. This gives the in‐situ density of the drilling mud, which together with the bulk moduli of the single constituents allow us to co...

In this article, the authors respond to J. D. Cohen, K. O. Dunbar, D. M. Barch and T. S. Braver's (1997) comment on their target article. The present article (a) takes issue with the characterization given by Cohen et al. of the authors' approach as a classical speed-of-processing account of Stroop effects, (b) discusses the value and relevance of other theoretical concepts, such as traditional accounts of working memory and parallel distributed processing (PDP) approaches to Stroop effects, (c) further examines the possibility that the differences the authors observed in Experiment 2 between normal participants' performance and that of participants with schizophrenia may have been due to distractor stimulus degradation, particularly for participants with schizophrenia, and (d) argues for the relevance of the prefrontal cortex, as well as other brain areas, in accounting for their results. The authors conclude with a final theoretical question.

The increasing demand for up-to-date 3-D geographic information systems (GIS) in planning, transportation, and utility management applications poses significant challenges to the Geomatics community. Of all the challenges in acquiring, building, maintaining, and using GIS, none is more central than that of dala acquisition. Obtaining the required spatial and attribute data by conventional methods such as aerial photogrammetry and terrestrial surveying is expensive, slow, or inaccurate. These methods are, therefore, not well suited for rapid updating. Fortunately, however, the development of land-based mobile mapping systems (MMS) has opened a new avenue to meet these challenges. Land-based MMS are capable of providing fast, efficient, cost-effective and complete data acquisition. As such, they are an innovative technology for creating and updating 3-D GIS databases both quickly and inexpensively. Basically, MMS are based on integrated navigation systems, mainly the integration of GP...

In conventional sheet forming processes, such as stamping or drawing, significant contact phenomena take place between workpiece and die surfaces. Especially, relative motion and normal loads generate friction which influences some aspects of processes such as material flow, tools wear and life and total force needed to complete the process. In the current paper an experimental test campaign has been carried out using a large scale pin-on-disk device designed and realized by the Authors to investigate the influence of pressure, sliding velocity and temperature. The purpose is to test the developed device and to find which and how these parameters mostly affect friction. The pin-on-disk test consists of two specimens, a pin and a plate representing respectively die and workpiece, which are compressed by means of a known force and then moved one over the other. Compression and friction forces are sampled during the tests and the friction coefficient is estimated as the ratio of these two forces. The tested materials are H13 die steel on FeP04 and AZ31 sheets.

Theoretical analysis of the effects of velocity of impact using suitable heat transfer equations expressed in forms of finite difference method was developed and used to determine their effects on the characteristic cooling parameters during quenching process. Various velocities of impact obtained by varying the heights of specimen drops were also used to experimentally determine their effects on characteristic cooling parameters and mechanical properties of medium carbon steel using water as the quenching medium. At height of drop of 0.5 m, 1.0 m, 1.5 m, and 2.0 m, the tensile strength of the material is 410.4, 496.12, 530.56, and 560.40 N/mm2 respectively. The corresponding hardness values are 42.4, 45.2, 46.2, 50.5 HRC respectively. It is found that as the velocity of impact increases, maximum cooling rate increases. Hardness and ultimate tensile strength also increase. There are good agreements between theoretical and experimentally determined values of critical cooling parameters of water during quenching operations.

A predrill estimate of pore pressure can be obtained from seismic velocities using a velocity-to–pore-pressure transform, but the seismic velocities need to be derived using methods having sufficient resolution for well planning purposes. For a deepwater Gulf of Mexico example, significant differences are found between the velocity field obtained using reflection tomography and that obtained using a conventional method based on the Dix equation. These lead to significant differences in the predicted pore pressure. Parameters ...

Blood flow simulations in computational fluid dynamics (CFD) are seen as a very attractive solution for diagnosing diseases. The main objective of this work is to simulate blood flow in healthy arteries. The governing equations for the Sisko model are presented in cylindrical coordinates. The finite volume method is used for the velocity and wall shear stress at healthy arteries. It is observed that the velocity profile increases due to an increase in Sisko fluid parameters and the radius of healthy arteries. With regard to the fact that blood flow in healthy arteries is non-Newtonian, the fluid obeys the Sisko fluid model. We contemplate that due to an increase in Sisko fluid parameters and the radius of healthy arteries, the wall shear stress profile increases and decreases, respectively.

Background and ObjectiveCryogen sprays are used for cooling human skin during various laser treatments. Since characteristics of such sprays have not been completely understood, the optimal atomizing nozzle design and operating conditions for cooling human skin remain to be determined.Cryogen sprays are used for cooling human skin during various laser treatments. Since characteristics of such sprays have not been completely understood, the optimal atomizing nozzle design and operating conditions for cooling human skin remain to be determined.Materials and MethodsTwo commercial cryogenic spray nozzles are characterized by imaging the sprays and the resulting areas on a substrate, as well as by measurements of the average spray droplet diameters, velocities, temperatures, and heat transfer coefficients at the cryogen-substrate interface; all as a function of distance from the nozzle tip.Two commercial cryogenic spray nozzles are characterized by imaging the sprays and the resulting areas on a substrate, as well as by measurements of the average spray droplet diameters, velocities, temperatures, and heat transfer coefficients at the cryogen-substrate interface; all as a function of distance from the nozzle tip.ResultsSize of spray cones and sprayed areas vary with distance and nozzle. Average droplet diameter and velocity increase with distance in the vicinity of the nozzle, slowly decreasing after a certain maximum is reached. Spray temperature decreases with distance due to the extraction of latent heat of vaporization. At larger distances, temperature increases due to complete evaporation of spray droplets. These three variables combined determine the heat transfer coefficient, which may also initially increase with distance, but eventually decreases as nozzles are moved far from the target.Size of spray cones and sprayed areas vary with distance and nozzle. Average droplet diameter and velocity increase with distance in the vicinity of the nozzle, slowly decreasing after a certain maximum is reached. Spray temperature decreases with distance due to the extraction of latent heat of vaporization. At larger distances, temperature increases due to complete evaporation of spray droplets. These three variables combined determine the heat transfer coefficient, which may also initially increase with distance, but eventually decreases as nozzles are moved far from the target.ConclusionsSprayed areas and heat extraction efficiencies produced by current commercial nozzles may be significantly modified by varying the distance between the nozzle and the sprayed surface. Lasers Surg. Med. 28:113–120, 2001. © 2001 Wiley-Liss, Inc.Sprayed areas and heat extraction efficiencies produced by current commercial nozzles may be significantly modified by varying the distance between the nozzle and the sprayed surface. Lasers Surg. Med. 28:113–120, 2001. © 2001 Wiley-Liss, Inc.

Abstract: In this article, we review some of the theoretical solutions used to describe swirl dominated flows in both unidirectional and bidirectional flow orientations. This short survey starts with the Rankine vortex and culminates in the presentation of a compressible solution of the bidirectional vortex. After classifying representative swirl motions as external or internal depending on physical boundary conditions, their commonalities are identified along with their relevance to either geophysical or industrial applications. We also identify ...