The role of learning on industrial simulation design and analysis

The capability of modeling real-world system operations has turned simulation into an indispensable problemsolving methodology for business system design and analysis. Today, simulation supports decisions ranging from sourcing to operations to finance, starting at the strategic level and proceeding towards tactical and operational levels of decision-making. In such a dynamic setting, the practice of simulation goes beyond being a static problem-solving exercise and requires integration with learning. This article discusses the role of learning in simulation design and analysis motivated by the needs of industrial problems and describes how selected tools of statistical learning can be utilized for this purpose

The Coal River Basin: A 2009 Water Budget Study

The Coal River Watershed covers an area of some 890 square miles in southern West Virginia of which 863 square miles was investigated in this study. Both online and field data were collected over period from January 13, 2009 to January 13, 2010. The basin was studied as a closed system having an input, which was precipitation, and outputs, rainfall interception, evapotranspiration, and stream discharge that was separated into base flow and overland flow. The effective rainfall of the watershed was calculated using the Thiessen polygon method to be 42 inches for the year, 48% of that water discharged by the Coal River, 33% intercepted by foliage, and 19% lost due to evapotranspiration. The stream flow was separated into overland and base flow both manually and using digital filtering. About 60% of the stream discharge is from groundwater and 40% from overland flow. During months of larger rainfall the base flow is less, and for low rainfall months the base flow higher

Nitroxide Radicals for Low Frequency Electron Paramagnetic Resonance Imaging (EPRI)

Optimization of nitroxides as probes for EPR imaging requires detailed understanding of spectral properties such as spin lattice relaxation times, spin packet linewidths, and nuclear hyperfine splitting. Initial measurements of relaxation times for six low molecular weight nitroxides at X-band stimulated further measurement at frequencies between 250 MHz and 34 GHz. The impact of tumbling was studied with perdeuterated 2,2,6,6-tetramethyl-4-piperidinyl-1-oxyl (PDT) in five solvents with viscosities resulting in tumbling correlation times, τR, between 4 and 50 ps. A set of three 14N/15N pairs of nitroxides in water was selected such that τR varied between 9 and 19 ps. To test the impact of structure on relaxation, three additional nitroxides with τR between 10 and 26 ps were studied. In the fast tumbling regime 1/T2 ~ 1/T1 and relaxation is dominated by spin rotation, modulation of A-anisotropy and a thermally activated process. The contribution to 1/T1 from spin rotation is independent of frequency and decreases as τR increases. The modulation of nitrogen hyperfine anisotropy increases as frequency decreases and as τR increases, dominating at low frequencies for τR~ 15 ps. The modulation of g anisotropy is significant only at 34 GHz. Inclusion of a thermally activated process was required to account for the observation that for most of the radicals, 1/T1 was smaller at 250 MHz than at 1-2 GHz. The thermally activated process likely arises from intramolecular motions of the nitroxide ring that modulate the isotropic A values. A phantom of three 4 mm tubes containing different 15N,2H-substituted nitroxides was constructed for use at 250 MHz. Projections for 2D spectral-spatial images were obtained by continuous wave (CW) and rapid scan (RS) EPR using a bimodal cross-loop resonator. Relative to CW projections obtained for the same data acquisition time (5 min), RS projections had significantly improved image quality. All experiments were facilitated by advancements in resonator design and testing, which are also described

Jet Lag From A Physics Point Of View

While the common believe is that dark/light timing causes jet lag, we argue that physics, not the biological clock, may be the main reason for this air travel disorder. We explored the change in voltage in the human brain due to the added voltage induced by flying over the magnetic field of the Earth, and we think that this induced voltage in the brain is significant enough to cause neurological changes that may trigger jet lag or other illnesses

Hot Gas Structure in the Elliptical Galaxy NGC 4472

We present X-ray spectroscopic and morphological analyses using Chandra ACIS and ROSAT observations of the giant elliptical galaxy NGC 4472 in the Virgo cluster. We discuss previously unobserved X-ray structures within the extended galactic corona. In the inner 2' of the galaxy, we find X-ray holes or cavities with radii of ~2 kpc, corresponding to the position of radio lobes. These holes were produced during a period of nuclear activity that began 1.2 x 10^7 years ago and may be ongoing. We also find an asymmetrical edge in the galaxy X-ray emission 3' (14 kpc) northeast of the core and an ~8' tail (36 kpc) extending southwest of the galaxy. These two features probably result from the interaction of NGC 4472 gas with the Virgo gas, which produces compression in the direction of NGC 4472's infall and an extended tail from ram pressure stripping. Assuming the tail is in pressure equilibrium with the surrounding gas, we compute its angle to our line of sight and estimate that its true extent exceeds 100 kpc. Finally, in addition to emission from the nucleus (first detected by Soldatenkov, Vikhlinin & Pavlinsky), we detect two small extended sources within 10'' of the nucleus of the galaxy, both of which have luminosities of ~7 x 10^38 erg/s.Comment: 25 pages, 11 figures, accepted by Ap

Observing Strategies for the NICI Campaign to Directly Image Extrasolar Planets

We discuss observing strategy for the Near Infrared Coronagraphic Imager (NICI) on the 8-m Gemini South telescope. NICI combines a number of techniques to attenuate starlight and suppress superspeckles: 1) coronagraphic imaging, 2) dual channel imaging for Spectral Differential Imaging (SDI) and 3) operation in a fixed Cassegrain rotator mode for Angular Differential Imaging (ADI). NICI will be used both in service mode and for a dedicated 50 night planet search campaign. While all of these techniques have been used individually in large planet-finding surveys, this is the first time ADI and SDI will be used with a coronagraph in a large survey. Thus, novel observing strategies are necessary to conduct a viable planet search campaign.Comment: 12 pages, 10 figures, submitted to Proceedings of the SPI

The SISO CSPI PDG standard for commercial off-the-shelf simulation package interoperability reference models

For many years discrete-event simulation has been used to analyze production and logistics problems in manufactur-ing and defense. Commercial-off-the-shelf Simulation Packages (CSPs), visual interactive modelling environ-ments such as Arena, Anylogic, Flexsim, Simul8, Witness, etc., support the development, experimentation and visua-lization of simulation models. There have been various attempts to create distributed simulations with these CSPs and their tools, some with the High Level Architecture (HLA). These are complex and it is quite difficult to assess how a set of models/CSP are actually interoperating. As the first in a series of standards aimed at standardizing how the HLA is used to support CSP distributed simula-tions, the Simulation Interoperability Standards Organiza-tion’s (SISO) CSP Interoperability Product Development Group (CSPI PDG) has developed and standardized a set of Interoperability Reference Models (IRM) that are in-tended to clearly identify the interoperability capabilities of CSP distributed simulations

NICI: combining coronagraphy, ADI, and SDI

The Near-Infrared Coronagraphic Imager (NICI) is a high-contrast AO imager at the Gemini South telescope. The camera includes a coronagraphic mask and dual channel imaging for Spectral Differential Imaging (SDI). The instrument can also be used in a fixed Cassegrain Rotator mode for Angular Differential Imaging (ADI). While coronagraphy, SDI, and ADI have been applied before in direct imaging searches for exoplanets. NICI represents the first time that these 3 techniques can be combined. We present preliminary NICI commissioning data using these techniques and show that combining SDI and ADI results in significant gains.Comment: Proc. SPIE, Vol. 7014, 70141Z (2008