Actual Runtime Research Articles

Relationship of Running Economy, Ventilatory Threshold, and Maximal Oxygen Consumption to Running Performance in High School Females

The purpose of the study was to relate three determinants of distance running success, (a) maximal oxygen consumption (VO2max), (b) ventilatory threshold (VT), and (c) running economy (RE), to actual running time in a 5-km race (ART). Twenty-four female runners (M age = 15.9 years) from four high school teams that competed at the Massachusetts All-State 5-km Cross Country Championship Meet and placed 1st, 7th, 19th, and 20th were tested in the laboratory. The mean VO2max of these runners was 61.7 ml.kg-1.min-1, HRmax 201 b.min-1, VEmax 100 L.min-1, and RER 1.10. The VT occurred at 79% of the VO2max, and HR of 184 b.min-1 (92% of HRmax). The velocity at VT (vVT) and velocity at VO2max (vVO2max) was correlated with ART, r(22) = .78 and .77 (p less than .001), respectively. The VO2 at VT and at maximal exercise was correlated with ART by r(22) = -.66 and -.69 (p less than .001), respectively. The VO2 at 215 m.min-1 (8 mph) was poorly related to ART, r(22) = -.05, p greater than .05. It was concluded that either of the derived variables vVT and vVO2max appear to explain significant variation in distance running performance among adolescent female cross country runners.

FLO52 ON HYPERCUBES: PERFORMANCE AND MODELLING OF A MULTIGRID EULER CODE

This paper evaluates the performance of hypercube machines on a computational fluid dynamics problem. Our evaluation focuses on a prototype of a class of widely used fluid dynamics codes, FLO52, written by Antony Jameson, which solves the two-dimensional steady Euler equations describing flow around an airfoil. In this paper, we give a description of FLO52, its hypercube mapping, and the code modifications to increase machine utilization. Results from two hypercube computers (a 16 node iPSC/2, and a 512 node NCUBE/ten) are presented and compared. In addition, we develop a mathematical model of the execution time as a function of several machine and algorithm parameters. This model accurately predicts the actual run times obtained. Predictions about future hypercubes are made using this timing model.

A fast algorithm for constructing Delaunay triangulations in the plane

This paper describes an algorithm for computing Delaunay triangulations of arbitrary collections of points in the plane. A FORTRAN 77 implementation of the scheme is given. For N points distributed randomly within a square domain, the expected run time for the algorithm is approximately 0(N 5 4 ) . Empirical tests, for N up to 10 000, indicate that the actual run time is substantially less than this prediction and is generally better than 0( N 1.1). Excluding the memory required to store the co-ordinates, the algorithm requires slightly greater than 14 N words of integer memory to complete a typical triangulation. The efficiency of the proposed algorithm is verified by comparing its performance with other Delaunay triangulation procedures. Uses of the algorithm include the generation of finite element meshes and the construction of contour plots.

Effects of forced exercise on the food intake of rats maintained on a 23-hr deprivation schedule

Adult male rats of the Sprague-Dawley strain were given daily forced exercise of progressively higher levels on motor-driven treadmills while maintained on a 23-hr food deprivation schedule. Food intake measures were taken for 68 days, spanning a range of 2–8 hr exercise-sessions per day (1–4 hr actual running time) at 1.46 km/hr. The food intake of both exercising and sedentary food-restricted animals was lower as compared to that of ad lib feeding animals. Exercise did not further suppress food intake. Shifts to higher exercise levels did not result in any transitory or permanent depression in food intake. It is concluded that high levels of exercise in trained male rats maintained on a 1-hr/day feeding schedule has no suppressive effects on food intake.

The Gradient Projection Algorithm for Multiple Routing in Message-Switched Networks

Various algorithms have been proposed for determining the routing paths designed to minimize the average overall message time delay in message-switched networks. In this paper we describe the application of the gradient projection algorithm to this problem. This algorithm is a gradient-type search procedure designed to handle constrained optimization problems, into which category the routing problem falls. Calculations of the computational complexity of this algorithm indicate that it is particularly well-suited to networks with a limited number of commodities or source-destination pairs. The algorithm is applied to a representative group of distributed-type networks, of varying complexity. Execution times for this algorithm are compared with those obtained using the flow deviation routing algorithm. These agree roughly with the results of the computational requirement calculations; i.e., this algorithm generally requires less execution time for networks with a relatively small number of commodities than does the flow deviation method. (The actual running time depends significantly on the choice of the initial flows or routing paths, however.) For those networks in which all network nodes may be expected to communicate with all other nodes, however, the flow deviation method would be expected to be superior.

Direct Methods in Reservoir Simulation

Abstract During the past decade, efforts in reservoir modeling have focused on the three areas of capability efficiency, and reliability. Capability means the ability to handle larger and more complex problems where complexity includes physical problems where complexity includes physical phenomena, such as gas percolation and variable phenomena, such as gas percolation and variable PVT properties, and severe heterogeneity due to PVT properties, and severe heterogeneity due to property variation or geometry, or both. Efficiency property variation or geometry, or both. Efficiency is increased by improving model formulations anti solution techniques to increase tolerable time-step size and reduce computer time per time step. Reliability refers to ease of use and minimum burden in selecting or experimenting with time-step size, solution technique options, iteration parameters, and closure tolerances. parameters, and closure tolerances. The single facet of a reservoir simulator that has the greatest combined influence in all three categories is the technique used to solve the large systems of equations arising from the numerical approximation of the nonlinear fluid flow equations. Available techniques include both direct solution and iterative methods such as ADIP, SOR, and SIP. Iterative methods are currently used almost to the exclusion of direct solution because of the significantly higher computer storage and time requirements of the latter. This paper describes some new ordering schemes for Gaussian elimination that reduce computing time and storage requirements by factors as large as 6 and 3, respectively, relative to more standard orderings. Computational work estimates are given for these methods, for the standard Gaussian ordering, and for several iterative methods. These work estimates are checked by comparisons of actual run times using different solution techniques. Numerical examples are given to illustrate the increased efficiency and reliability that can be achieved in many cases through use of the new direct solution methods. Introduction It is well known that the way we number or order the unknowns of a sparse system of linear algebraic equations can drastically affect the amount of computation and storage for a direct solution. However, until recently the best ordering scheme that appeared in the literature numbered the points of a three-dimensional grid first along the shortest direction - i.e., the dimension with the fewest number of grid points - then in the next shortest direction, and finally in the longest direction. This ordering, which we shall call the standard ordering for Gaussian elimination is still widely used even though it is substantially slower than many other orderings. Ogbuobiri et al. present a survey of the literature related to ordering schemes that exploit matrix sparsity. These schemes are grouped into the two classes of matrix-banding schemes and optimal or pseudo-optimal schemes. The latter schemes pseudo-optimal schemes. The latter schemes purport to yield generally greater efficiency. purport to yield generally greater efficiency. In a recent paper, Georges has shown that for five-point difference approximations on square n x n two-dimensional grids, the total work for certain orderings of the grid points is less than C1n3 and the storage is less than C2n2 log n, compared with n4 and n3, respectively, for the standard ordering. Moreover, George has shown that no ordering scheme can require less work than the order of n3. For the special case of n - 21 he shows that work W is less than 10n3 and the storage S is less than 8ln2 for symmetric matrices. For nonsymmetric matrices these results become W less than 20n3 and S less than 16ln2, respectively. In this paper we describe some specific orderings in the matrix-banding class. Analyses of work and storage requirements are given for these orderings as applied to the diffusivity-type pressure equation that arises in reservoir simulation problems. These work and storage requirements are compared with those of the standard Gaussian ordering and of some iterative methods. These comparisons are performed for problems ranging from simple performed for problems ranging from simple homogeneous squares to practical reservoir problems of typical heterogeneity and irregular problems of typical heterogeneity and irregular geometry. The work requirements of the orderings presented here are also compared experimentally with those of one of the leading pseudo-optimal schemes. SPEJ P. 295

Ultrasonic disaggregation of sandstones and siltstones

A technique is described for the use of a probe-type ultrasonic device to disaggregate selected Triassic continental sandstones, siltstones, shales, and several other rock types. The samples used in developing this method were particularly resistant to disaggregation by standard methods, which failed or were minimally successful. The average time needed to disaggregate samples was much less for those treated with the probe sonifier than in the tank-type of sonifier. There are however similar problems which may result from the use of either of these, including the necessity of guarding against rounding of grains and loss of relatively softer minerals by abrasion. Sandstones average 25 minutes per sample as compared with 13 minutes for shales and 58 minutes for the siltstones. Limestones or marbles take considerably longer with very poor results unless they are calcarenites in which the fragments are well separated by clay minerals. The time referred to includes only the actual running time of the apparatus and not the time involved in other phases of the procedure The probe-type ultrasonic device may also be used satisfactorily at the beginning of hydrometer or pipette analysis of clays in lieu of overturning the graduate cylinder or stirring with other devices In addition, if flocculation occurs after the test has begun, the probe may be inserted directly into the graduate cylinder and run for 5 to 10 minutes. This eliminates the necessity of either transfer of the suspension for further stirring, or stirring with large stirring devices which might result in some loss of the suspension.