CASL - A language for automating the implementation of computer architectures

technical reportThe computer Architecture Specification Language (CASL), described in this paper, is intended for use by computer architects CASL is a state machine description language especially useful for describing digital systems at the "register transfer" level and designed to meet the needs of the computer architect as a design and documentation medium. A machine described in CASL may be decomposed into cooperating Modules, each representing an asynchronous finite state machine. Each Module consiste of an Abstractions, Structure, and Procedure section. An architect may use the Abstractions section to define his own data representations and primitive operations. The Structure section describes structural elements section describes structural elements (combinatorial and sequential hardware "building blocks") and connections (explicit specifications of each data path). The Procedure section is a textual (nearly ALGOL-like) representation of the state transition graph and the sets of control signals issued concurrently in each state to drive the structure. Statements in each state are collateral, rather than sequential, and CASE structures are used for conditional selection of control signals to be issued by a state. A macro facility is provided to encode groups of control signals

Sand stirred by chaotic advection

We study the spatial structure of a granular material, N particles subject to inelastic mutual collisions, when it is stirred by a bidimensional smooth chaotic flow. A simple dynamical model is introduced where four different time scales are explicitly considered: i) the Stokes time, accounting for the inertia of the particles, ii) the mean collision time among the grains, iii) the typical time scale of the flow, and iv) the inverse of the Lyapunov exponent of the chaotic flow, which gives a typical time for the separation of two initially close parcels of fluid. Depending on the relative values of these different times a complex scenario appears for the long-time steady spatial distribution of particles, where clusters of particles may or not appear.Comment: 4 pages, 3 figure

Turbulent thermal diffusion in a multi-fan turbulence generator with the imposed mean temperature gradient

We studied experimentally the effect of turbulent thermal diffusion in a multi-fan turbulence generator which produces a nearly homogeneous and isotropic flow with a small mean velocity. Using Particle Image Velocimetry and Image Processing techniques we showed that in a turbulent flow with an imposed mean vertical temperature gradient (stably stratified flow) particles accumulate in the regions with the mean temperature minimum. These experiments detected the effect of turbulent thermal diffusion in a multi-fan turbulence generator for relatively high Reynolds numbers. The experimental results are in compliance with the results of the previous experimental studies of turbulent thermal diffusion in oscillating grids turbulence (Buchholz et al. 2004; Eidelman et al. 2004). We demonstrated that turbulent thermal diffusion is an universal phenomenon. It occurs independently of the method of turbulence generation, and the qualitative behavior of particle spatial distribution in these very different turbulent flows is similar. Competition between turbulent fluxes caused by turbulent thermal diffusion and turbulent diffusion determines the formation of particle inhomogeneities.Comment: 9 pages, 9 figure, REVTEX4, Experiments in Fluids, in pres

Size-selective concentration of chondrules and other small particles in protoplanetary nebula turbulence

Size-selective concentration of particles in a weakly turbulent protoplanetary nebula may be responsible for the initial collection of chondrules and other constituents into primitive body precursors. This paper presents the main elements of this process of turbulent concentration. In the terrestrial planet region, both the characteristic size and size distribution of chondrules are explained. "Fluffier" particles would be concentrated in nebula regions which were at a lower gas density and/or more intensely turbulent. The spatial distribution of concentrated particle density obeys multifractal scaling}, suggesting a close tie to the turbulent cascade process. This scaling behavior allows predictions of the probability distributions for concentration in the protoplanetary nebula to be made. Large concentration factors (>10^5) are readily obtained, implying that numerous zones of particle density significantly exceeding the gas density could exist. If most of the available solids were actually in chondrule sized particles, the ensuing particle mass density would become so large that the feedback effects on gas turbulence due to mass loading could no longer be neglected. This paper describes the process, presenting its basic elements and some implications, without including the effects of mass loading.Comment: 34 pages, 7 figures; in press for Astrophys. J; expected Jan 01 2001 issu

Ergodic properties of a model for turbulent dispersion of inertial particles

We study a simple stochastic differential equation that models the dispersion of close heavy particles moving in a turbulent flow. In one and two dimensions, the model is closely related to the one-dimensional stationary Schroedinger equation in a random delta-correlated potential. The ergodic properties of the dispersion process are investigated by proving that its generator is hypoelliptic and using control theory

Scholar-activists in an expanding European food sovereignty movement

This article analyzes the roles, relations, and positions of scholar-activists in the European food sovereignty movement. In doing so, we document, make visible and question the political dimensions of researchers' participation in the movement. We argue that scholar-activists are part of the movement, but are distinct from the affected constituencies, put in place to ensure adequate representation of key movement actors. This is because scholar-activists lack a collective identity, have no processes to formulate collective demands, and no mechanisms for inter-researcher and researchers-movement communication. We reflect on whether and how scholar-activists could organize, and discuss possible pathways for a more cohesive and stronger researcher engagement in the movement.</p

Dynamics of a small neutrally buoyant sphere in a fluid and targeting in Hamiltonian systems

We show that, even in the most favorable case, the motion of a small spherical tracer suspended in a fluid of the same density may differ from the corresponding motion of an ideal passive particle. We demonstrate furthermore how its dynamics may be applied to target trajectories in Hamiltonian systems.Comment: See home page http://lec.ugr.es/~julya

Turbulent Diffusion and Turbulent Thermal Diffusion of Aerosols in Stratified Atmospheric Flows

The paper analyzes the phenomenon of turbulent thermal diffusion in the Earth atmosphere, its relation to the turbulent diffusion and its potential impact on aerosol distribution. This phenomenon was predicted theoretically more than 10 years ago and detected recently in the laboratory experiments. This effect causes a non-diffusive flux of aerosols in the direction of the heat flux and results in formation of long-living aerosol layers in the vicinity of temperature inversions. We demonstrated that the theory of turbulent thermal diffusion explains the GOMOS aerosol observations near the tropopause (i.e., the observed shape of aerosol vertical profiles with elevated concentrations located almost symmetrically with respect to temperature profile). In combination with the derived expression for the dependence of the turbulent thermal diffusion ratio on the turbulent diffusion, these measurements yield an independent method for determining the coefficient of turbulent diffusion at the tropopause. We evaluated the impact of turbulent thermal diffusion to the lower-troposphere vertical profiles of aerosol concentration by means of numerical dispersion modelling, and found a regular upward forcing of aerosols with coarse particles affected stronger than fine aerosols.Comment: 19 pages, 10 figure

Are the results from the 2014 UK national survey on the management of diabetic ketoacidosis applicable to individual centres?

Background: In 2013 the Joint British Diabetes Societies published an update to their 2010 guideline on the management of diabetic ketoacidosis (DKA). In 2014 a national survey was conducted to assess the management of DKA across the UK using the JBDS or local guidelines. Hospitals were invited to submit data on 5 people presenting with DKA. These data were published in 2016. However, whether those national results were applicable to individual hospitals remains unknown. Aim: To assess the management of people presenting with DKA at a single hospital and compare the results with the national dataset. Methods: Using the identical data collection tool as used in the national survey we collected information on 40 subjects (a total of 52 admissions) admitted with DKA between April 2014 and July 2015. Results: The data collected locally were very similar to those found in the national dataset. The management of DKA was best during the first few hours after admission, then biochemical and physical monitoring frequency decreased. The number of people who developed hypokalaemia and hypoglycaemia were very similar to the national data. Rates of biochemical improvement were slightly better locally. Conclusions: The data from the national DKA survey, even though based on a maximum of 5 people per hospital from across the UK are applicable at a hospital level