James J. Filliben

Comparing VM-Placement Algorithms for On-Demand Clouds

Much recent research has been devoted to investigating algorithms for allocating virtual machines (VMs) to physical machines (PMs) in infrastructure clouds. Many such algorithms address distinct problems, such as initial placement, consolidation, or tradeoffs between honoring service-level agreements and constraining provider operating costs. Even where similar problems are addressed, each individual research team evaluates proposed algorithms under distinct conditions, using various techniques, often targeted to a small collection of VMs and PMs. In this paper, we describe an objective method that can be used to compare VM-placement algorithms in large clouds, covering tens of thousands of PMs and hundreds of thousands of VMs. We demonstrate our method by comparing 18 algorithms for initial VM placement in on-demand infrastructure clouds. We compare algorithms inspired by open-source code for infrastructure clouds, and by the online bin-packing literature.

Extreme wind load estimates based on the Gumbel distribution of dynamic pressures: an assessment

We present a contribution to the current debate on whether it is more appropriate to fit a Gumbel distribution to the time series of the extreme dynamic pressures (i.e. of the squares of the extreme wind speeds) than to fit an extreme value distribution to the time series of the extreme wind speeds themselves. It has been shown that the use of time series of the extreme dynamic pressures would be justified if the time series of the wind speed data taken at small intervals (e.g. 1 h) were, at least approximately, Rayleigh-distributed. We show that, according to sets of data we believe are typical, this is not the case. In addition, we show results of probability plot correlation coefficient (PPCC) analyses of 100 records of sample size 23 to 54, according to which the fit of reverse Weibull distributions to largest yearly wind speeds is considerably better than the fit of Gumbel distributions to the corresponding largest yearly dynamic pressures. We interpret the data and results presented in the paper as indicating that there is no convincing support to date for the hypothesis that the Gumbel distribution should be used as a model of extreme dynamic pressures.

Taguchi's fixed-element arrays are fractional factorials

Taguchi developed his catalog of orthogonal arrays from mathematical procedures published in well-known English language journals. These arrays evolved as extensions of factorial plans and latin squares. This paper illustrates the fractional factorial n..

Comparison of Segmentation Algorithms For Fluorescence Microscopy Images of Cells

The analysis of fluorescence microscopy of cells often requires the determination of cell edges. This is typically done using segmentation techniques that separate the cell objects in an image from the surrounding background. This study compares segmentation results from nine different segmentation techniques applied to two different cell lines and five different sets of imaging conditions. Significant variability in the results of segmentation was observed that was due solely to differences in imaging conditions or applications of different algorithms. We quantified and compared the results with a novel bivariate similarity index metric that evaluates the degree of underestimating or overestimating a cell object. The results show that commonly used threshold‐based segmentation techniques are less accurate than k‐means clustering with multiple clusters. Segmentation accuracy varies with imaging conditions that determine the sharpness of cell edges and with geometric features of a cell. Based on this observation, we propose a method that quantifies cell edge character to provide an estimate of how accurately an algorithm will perform. The results of this study will assist the development of criteria for evaluating interlaboratory comparability. Published 2011 Wiley‐Liss, Inc.

Taguchi's orthogonal arrays are classical designs of experiments

Taguchi’s catalog of orthogonal arrays is based on the mathematical theory of factorial designs and difference sets developed by R. C. Bose and his associates. These arrays evolved as extensions of factorial designs and latin squares. This paper (1) describes the structure and constructions of Taguchi’s orthogonal arrays, (2) illustrates their fractional factorial nature, and (3) points out that Taguchi’s catalog can be expanded to include orthogonal arrays developed since 1960.

Isochoric and isobaric glass formation : Similarities and differences

Pressure-volume-temperature (PVT) studies were performed on a glass-forming polymer, poly(carbonate) (PC), under both isobaric and isochoric (constant volume) conditions. An isochoric glass transition was observed and the formation points were found to be consistent with those obtained isobarically. Although the isobaric and isochoric responses were, as expected, the same in the rubbery state, the glassy state values were found to be different and dependent upon the glass formation history. The isobaric data exhibited larger changes in going from the rubber to the glass, hence a stronger glass transition, than did the isochoric data. Inserting the experimental values for the thermal expansion coefficient α and isothermal compressibility β, into appropriate thermodynamic relations, measures of the strength of each transition are defined. Strength estimates based on literature values of α and β are compared to the experimental measures of the isochoric and isobaric transitions. In addition, both the isobaric and isochoric PVT results were analyzed in terms of the Fox and Flory free volume theory which assumes that the glass transition is an iso-free volume state. While the isobaric results were consistent with the Fox and Flory theory, the isochoric results were not consistent with the idea of an iso-free volume glass transition.

DATAPLOT—an interactive high-level language for graphics, non-linear fitting, data analysis, and mathematics

<italic>This paper describes the design philosphy and features of DATAPLOT—a high-level (free-format English-like syntax) language for:</italic> <italic>1) graphics (continuous or discrete);</italic> <italic>2) fitting (linear or non-linear);</italic> <italic>3) general data analysis;</italic> <italic>4) mathematics.</italic> <italic>DATAPLOT was developed originally in 1977 in response to data analysis problems encountered at the National Bureau of Standards. It has subsequently been the most heavily-used interactive graphics and non-linear fitting language at NBS. It is a valuable tool not only for “raw” graphics, but also for manuscript preparation, modeling, data analysis, data summarization, and mathematical analysis. DATAPLOT may be run either in batch mode or interactively, although it was primarily designed for (and is most effectively used in) an interactive environmnet. DATAPLOT graphics may appear on many different types of output devices. Due to its modular design and underlying ANSI FORTRAN (PFORT) code, DATAPLOT is portable to a wide variety of computers.</italic> <italic>The paper is divided into three general parts: part 1 deals with background motivation and design philosophy; part 2 deals with capability and implementation features; part 3 deals with a comparison of DATAPLOT to other systems/languages.</italic>

Addressing the Amorphous Content Issue in Quantitative Phase Analysis: The Certification of NIST Standard Reference Material 676a

A non-diffracting surface layer exists at any boundary of a crystal and can comprise a mass fraction of several percent in a finely divided solid. This has led to the long-standing issue of amorphous content in standards for quantitative phase analysis (QPA). NIST standard reference material (SRM) 676a is a corundum (α-Al(2)O(3)) powder, certified with respect to phase purity for use as an internal standard in powder diffraction QPA. The amorphous content of SRM 676a is determined by comparing diffraction data from mixtures with samples of silicon powders that were engineered to vary their specific surface area. Under the (supported) assumption that the thickness of an amorphous surface layer on Si was invariant, this provided a method to control the crystalline/amorphous ratio of the silicon components of 50/50 weight mixtures of SRM 676a with silicon. Powder diffraction experiments utilizing neutron time-of-flight and 25 keV and 67 keV X-ray energies quantified the crystalline phase fractions from a series of specimens. Results from Rietveld analyses, which included a model for extinction effects in the silicon, of these data were extrapolated to the limit of zero amorphous content of the Si powder. The certified phase purity of SRM 676a is 99.02% ± 1.11% (95% confidence interval). This novel certification method permits quantification of amorphous content for any sample of interest, by spiking with SRM 676a.

Wind direction effects on cladding and structural loads

Abstract A simple procedure is proposed for estimating wind loads corresponding to various return periods, which takes into account directional information on both wind speeds and aerodynamic response. Examples of the application of the procedure are given, which show that cladding loads calculated without taking directional information on extreme wind speeds into account may in certain cases be larger than the actual loads by a factor of two or more. It is also shown that it is not appropriate, in general, to account for wind direction effects by multiplying loads determined without regard for these effects by a reduction factor of 0.8, as has been suggested in the literature. In its present form, the procedure is applicable to cladding panels and to members of relatively rigid structures in regions not subjected to hurricane winds.

Reference Material 8785: Air Particulate Matter on Filter Media

Reference Material (RM) 8785 Air Particulate Matter on Filter Media is intended primarily for use in the evaluation of analytical methods used to characterize the carbon composition of atmospheric fine particulate matter (PM) for national air quality monitoring programs. This RM consists of a fine fraction (nominally < 2.5 μ m aerodynamic diameter) of standard reference material (SRM) 1649a Urban Dust resuspended in air and filtered onto quartz-fiber filters. RM 8785 will also provide the atmospheric-chemistry and ocean-sciences communities with a means to intercompare methods and laboratories for the measurement of elemental (black) carbon. RM 8785 has values assigned for total carbon, elemental carbon, and organic carbon mass fractions measured according to two thermal–optical methods: the Interagency Monitoring of Protected Visual Environments (IMPROVE) and Speciation Trends Network–National Institute of Occupational Safety and Health (STN–NIOSH) protocols. Each filter is uniquely identified by its air particulate matter (APM) number and its gravimetrically determined mass of fine SRM 1649a. We will discuss the method used to produce RM 8785 and the results of an intermethod and interlaboratory comparison that provided assigned values for the above analytes.