Understanding the atomic-scale contrast in Kelvin Probe Force Microscopy

A numerical analysis of the origin of the atomic-scale contrast in Kelvin probe force microscopy (KPFM) is presented. Atomistic simulations of the tip-sample interaction force field have been combined with a non-contact Atomic Force Microscope/KPFM simulator. The implementation mimics recent experimental results on the (001) surface of a bulk alkali halide crystal for which simultaneous atomic-scale topographical and Contact Potential Difference (CPD) contrasts were reported. The local CPD does reflect the periodicity of the ionic crystal, but not the magnitude of its Madelung surface potential. The imaging mechanism relies on the induced polarization of the ions at the tip-surface interface owing to the modulation of the applied bias voltage. Our findings are in excellent agreement with previous theoretical expectations and experimental observations

A constructive version of Birkhoff's ergodic theorem for Martin-L\"of random points

A theorem of Ku\v{c}era states that given a Martin-L\"of random infinite binary sequence {\omega} and an effectively open set A of measure less than 1, some tail of {\omega} is not in A. We first prove several results in the same spirit and generalize them via an effective version of a weak form of Birkhoff's ergodic theorem. We then use this result to get a stronger form of it, namely a very general effective version of Birkhoff's ergodic theorem, which improves all the results previously obtained in this direction, in particular those of V'Yugin, Nandakumar and Hoyrup, Rojas.Comment: Improved version of the CiE'10 paper, with the strong form of Birkhoff's ergodic theorem for random point

Coupling Methodology within the Software Platform Alliances

CEA, ANDRA and EDF are jointly developing the software platform ALLIANCES which aim is to produce a tool for the simulation of nuclear waste storage and disposal repository. This type of simulations deals with highly coupled thermo-hydro-mechanical and chemical (T-H-M-C) processes. A key objective of Alliances is to give the capability for coupling algorithms development between existing codes. The aim of this paper is to present coupling methodology use in the context of this software platform.Comment: 7 page

We need to talk about engineering policy

The governance of engineering, unlike science, is rarely discussed in the academy. We analyse this issue in relation to the prevalence of the term ‘engineering policy’ in contrast to ‘science policy’ as a means of demonstrating the nature of the different treatment of these concepts inside the academy and outside. We show that ‘engineering policy’ as a term has almost no academic inquiry relative to science policy, and that even ‘engineering’ is marginalised in critical social science domains like Science and Technology Studies, as others have noted. Further, we extend this exploration with regard to the visibility of engineering policy in practice communities where it ought to be visible but isn't. Specifically, we use the UK government and governance communities as a space to show how engineering and policy for engineering remain side-lined in policy practice. Given how central engineering is to society, the obscurity of its governance mechanisms and the absence of critical scrutiny of engineering policy, we propose a research and action agenda as a means of stimulating action and coalescing a community of stakeholders to redress this situation with some urgency

HUBUNGAN TINGKAT PENDIDIKAN KEPALA KELUARGA DENGAN TINGKAT KESIAPSIAGAAN BENCANA TSUNAMI DI DESA ALUE NAGA KECAMATAN SYIAH KUALA KOTA BANDA ACEH

ABSTRAKTsunami pada Desember 2004, yang dipicu oleh gempa berkekuatan 9.0 SR di sebelah utara pulau Sumatra mengakibatkan kerugian yang sangat besar. Aceh merupakan daerah paling parah dengan korban tewas sebanyak 123.000 jiwa, 113.000 orang hilang, 406.000 orang kehilangan tempat tinggal. Faktor utama timbulnya banyak korban akibat bencana gempa bumi adalah kurangnya pengetahuan masyarakat tentang bencana dan kesiapan mereka dalam mengantisipasi bencana. Sekolah merupakan salah satu media transformasi ilmu pengetahuan yang paling efektif dalam menyerap dan mengaplikasikan pengetahuan kesiapan menghadapi bencana dengan menggunakan metode yang tepat dan benar. Tujuan penelitian ini adalah untuk mengetahui apakah ada hubungan tingkat pendidikan formal dengan tingkat kesiapsiagaan dalam menghadapi bencana tsunami. Populasi penelitian ini 494 orang kepala keluarga dan terdapat jumlah sampel sebanyak 84 responden. Pengambilan sampel yang digunakan adalah non-probability sampling. Pengumpulan data menggunakan angket dengan wawancara terarah dan diolah dengan menggunakan statistik uji Kolmogorov Smirnov dengan hasil 55 responden (66%) memiliki kesiapsiagaaan rendah dan tingkat pendidikan yang paling banyak adalah pendidikan dasar berjumlah 67 responden (80%). Kesimpulan dalam penelitian ini adalah terdapat pengaruh tingkat pendidikan dengan tingkat kesiapsiagaan kepala keluaga di Desa Alue Naga kecamatan Syiah Kuala Kota Banda Aceh dengan nilai p=0,000 (pBanda Ace

Homogenization of fibre reinforced composite with gradient enhanced damage model

Classical finite element simulations face the problems of losing uniqueness and strain localization when the strain softening of materials is involved. Thus, when using continuum damage model or plasticity softening model, numerical convergence will not be obtained with the refinement of the finite element discretization when strain localization occurs. Gradient-enhanced softening and non-local continua models have been proposed by several researchers in order to solve this problem. In such approaches, high-order spatial gradients of state variables are incorporated in the macroscopic constitutive equations. However, when dealing with complex heterogeneous materials, a direct simulation of the macroscopic structures is unreachable, motivating the development of non-local homogenization schemes. In this work, a non-local homogenization procedure is proposed for fiber reinforced materials. In this approach, the fiber is assumed to remain linear elastic while the matrix material is modeled as elasto-plastic coupled with a damage law described by a non-local constitutive model. Toward this end, the mean-field homogenization is based on the knowledge of the macroscopic deformation tensors, internal variables and their gradients, which are applied to a micro- structural representative volume element (RVE). Macro-stress is then obtained from a homogenization process