Platform‐independent profiling in a virtual execution environment

Virtual execution environments, such as the Java virtual machine, promote platform‐independent software development. However, when it comes to analyzing algorithm complexity and performance bottlenecks, available tools focus on platform‐specific metrics, such as the CPU time consumption on a particular system. Other drawbacks of many prevailing profiling tools are high overhead, significant measurement perturbation, as well as reduced portability of profiling tools, which are often implemented in platform‐dependent native code. This article presents a novel profiling approach, which is entirely based on program transformation techniques, in order to build a profiling data structure that provides calling‐context‐sensitive program execution statistics. We explore the use of platform‐independent profiling metrics in order to make the instrumentation entirely portable and to generate reproducible profiles. We implemented these ideas within a Java‐based profiling tool called JP. A significant novelty is that this tool achieves complete bytecode coverage by statically instrumenting the core runtime libraries and dynamically instrumenting the rest of the code. JP provides a small and flexible API to write customized profiling agents in pure Java, which are periodically activated to process the collected profiling information. Performance measurements point out that, despite the presence of dynamic instrumentation, JP causes significantly less overhead than a prevailing tool for the profiling of Java code. Copyright © 2008 John Wiley & Sons, Ltd.     

Is there a space for additional renewable energy in the Norwegian power system? Potential for reduced global emission?

This paper presents the results of a Norwegian power system analysis. An energy system analysis model based on linear programming is used for modelling and optimisation. The analyses cover a number of scenarios where the studied system is subjected to changes by introducing other renewable energy sources, energy conservation measures and measures to promote renewable energy. The study shows that due to a combination of cheap hydropower and high investment costs, it is quite difficult for new generation units to be profitable. This is also true during periods of low precipitation where the system tends to survive on imported power instead of investing in new generation units. However, this does not apply to energy conservation measures that easily enter the system. On the other hand, biomass based CHP, wind power and wave power could be viable if measures are introduced to promote their use. Most of the scenarios show a high potential for reducing global emissions.     

EBSD技术在大塑性变形制备超细晶与纳米材料中的应用：试样制备、参数优化与数据分析

在场发射扫描电镜的帮助下,电子背散射技术（EBSD）能用来研究大小低达几十纳米的晶粒（或亚晶粒）,其角分辨率达~0.5°。EBSD 技术的快速发展（电子衍射花样的采集速度已高达1100点/s）使其相关领域的科技论文发表数量迅速增加。本文评述了 EBSD 的试样制备、参数优化和数据分析,特别是在大塑性变形（SPD）制备超细晶和纳米材料方面的应用。总结了电化学抛光、二氧化硅乳液机械抛光和离子束抛光等EBSD试样制备技术的优缺点和实用参数。结果表明,离子束抛光技术是一项通用的、几乎适用于所有EBSD试样的有效抛光方法。随着EBSD扫描步长的变化,花样的标定率存在一个极大值。最优化的EBSD扫描步长取决于试样图片的放大倍数和数据采集板的分辨率（或电子步长）。对晶粒和亚晶粒、织构和晶界结构等进行分析是EBSD的基本功能。EBSD也可对塑性变形的应变和存储能等进行分析。     

Formation and Growth of Clusters of Sulfur Dioxide

Formation and growth of neutral SO₂ clusters is investigated in an adiabatic-expansion setup by means of sulfur 2p (S2p) photoelectron spectroscopy and theoretical modeling. The shift in S2p ionization energy between the cluster and a single molecule, i.e., IE(cluster)-IE(monomer), is recorded and used to monitor the mean cluster size over a wide range of expansion conditions. The produced clusters were shown to fall into two different size regimes. Comparison between theoretical simulations and experimental observations suggests that while the smallest clusters belong to the ultrafine particle mode and have a liquid-like structure, the larger clusters belong to the accumulation mode of fine particles and possibly have a frozen cluster core. The transition between the two size/structure regimes occurs over a narrow interval in expansion conditions and may possibly reflect a change in growth mechanism from monomer addition to growth by cluster-cluster collisions.

(c) Jarle Harnes, Mahmoud Abu-Samha, Mathias Winkler, and Knut J. Børve     

Effects of psychological hardiness, job demands, and job control on sickness absence: A prospective study.

This study prospectively investigated the effects of psychological hardiness, job control, and job demands on medically certified sickness absence. Data from a questionnaire survey were combined with archival data for sickness absence among 7,239 civilian and military employees of the Norwegian Armed Forces (84.3% male, 69.8% military). A 2-component hurdle regression was used in the statistical analyses of the sickness absence data. After controlling for age, sex, and baseline absence, hardiness predicted both the likelihood of having any sickness absence (odds ratio = 0.97) and the number of absence spells (a 6.5% decrease in the expected count for 1 standard deviation change in hardiness). In addition, an interaction was found among hardiness, job control, and psychological demands. When demands were high, high job control was associated with more absence among employees with low levels of hardiness. Together, these findings point to hardiness as an important individual resource in relation to health, and that it is necessary to consider individual differences when examining the effects of work characteristics. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A parallel global adaptive quadrature algorithm for hypercubes

We have developed a one-dimensional parallel global adaptive quadrature algorithm for a machine with hypercube architecture, and studied the heuristics present in the algorithm. A mathematical model for how long time it takes to process a balanced tree of sub-intervals under certain (almost implementable) conditions is developed. The results from numerical experiments are given. The speedups achieved depend on the problem and are ranging from 0.83 to 30.5 on a 32-processor hypercube.     

Establishing a high-accuracy spectral response scale in the near infrared with digital filters

Spectrally invariant detectors are commonly used to interpolate or extrapolate the responsivity of InGaAs detectors in the infrared from absolute calibrations at a few wavelengths. The random noise in such detectors limits the accuracy that can be achieved in a narrowband, double-monochromator setup. We propose the application of a dedicated digital filter, which reduces the uncertainty by 30%, and combine it by calibrating a group of three detectors. The uncertainties are propagated from the observed variance in the relative measurement to the combined uncertainty of 0.4% (2sigma) in the responsivity values of the InGaAs detectors in the range of 1010-1640 nm.     

Conservation of energy for schemes applied to the propagation of shallow‐water inertia‐gravity waves in regions with varying depth

The linear equations governing the propagation of inertia‐gravity waves in geophysical fluid flows are discretized on the Arakawa C‐grid using centered differences in space. In contrast to the constant depth case it is demonstrated that varying depth may give rise to increasing energy (and loss of stability) using the natural approximations for the Coriolis terms found in many well‐known codes. This is true no matter which numerical method is used to propagate the equations. By a simple trick based on a modified weighting that ensures that the propagation matrices for the spatially discretized equations become similar to skew‐symmetric matrices, this problem is removed and the energy is conserved in regions with varying depth too. We give a number of examples both of model problems and large‐scale problems in order to illustrate this behaviour. In real applications diffusion, explicit through frictional terms or implicit through numerical diffusion, is introduced both for physical reasons, but often also in order to stabilize the numerical experiments. The growing modes associated with varying depth, the C‐grid and equal weighting may force us to enhance the diffusion more than we would like from physical considerations. The modified weighting offers a simple solution to this problem. Copyright © 2000 John Wiley & Sons, Ltd.     

The Cut&Glue mesh generation algorithm

This paper describes a technique for generating quadrilateral finite element meshes on convex, four-sided patches, given an arbitrary number of elements along each side of the patch. The technique first generates a subdivision with the correct topological structure and smoothes the subdivision to obtain elements of acceptance shape for finite element analysis. The correct mesh topology is obtained from a regular subdivision by cutting rectangular corners of appropriate size and interconnecting the sides introduced by the cuts.The method can also be applied on three-dimensional patches producing meshes of brick elements with gradations in all directions.