The ATLAS TileCal Read-Out Drivers Signal Reconstruction

TileCal is the hadronic calorimeter of the ATLAS experiment at the LHC collider at CERN. The Read-Out Drivers (ROD) are the core of the off-detector electronics. The main components of the RODs are the Digital Signal Processor (DSP) placed on the Processing Unit (PU) dautherboards. This paper describes the DSP code and its performance with calibration and real data. The code is divided into two different parts: the first part contains the core functionalities and the second one the reconstruction algorithms. The core acts as an operating system and it controls the configuration, the data reception, transmission, online monitoring and the synchronization between front-end data and the Trigger information. The reconstruction algorithms implemented on the DSP are the Optimal Filtering (OF), Muon Tagging (MTag) and Total Transverse Energy (ET) calculation. The OF algorithm reconstructs the deposited energy and the arrival time of the data on every calorimeter cell within a front-end module. This reconstructed energy is used by the MTag algorithm to tag low transverse momentum muons that may escape the ATLAS muon spectrometer Level 1 trigger whereas the ET algorithm computes the total transverse energy and the projection on X and Y for the entire module that will be used by the Level 2 trigger system. The DSP code performance is being validated with comparisons with offline reconstruction. The DSP performance is evaluated using cali bration data from Charge Injection System

A physical model suggests that hip-localized balance sense in birds improves state estimation in perching: implications for bipedal robots

In addition to a vestibular system, birds uniquely have a balance-sensing organ within the pelvis, called the lumbosacral organ (LSO). The LSO is well developed in terrestrial birds, possibly to facilitate balance control in perching and terrestrial locomotion. No previous studies have quantified the functional benefits of the LSO for balance. We suggest two main benefits of hip-localized balance sense: reduced sensorimotor delay and improved estimation of foot-ground acceleration. We used system identification to test the hypothesis that hip-localized balance sense improves estimates of foot acceleration compared to a head-localized sense, due to closer proximity to the feet. We built a physical model of a standing guinea fowl perched on a platform, and used 3D accelerometers at the hip and head to replicate balance sense by the LSO and vestibular systems. The horizontal platform was attached to the end effector of a 6 DOF robotic arm, allowing us to apply perturbations to the platform analogous to motions of a compliant branch. We also compared state estimation between models with low and high neck stiffness. Cross-correlations revealed that foot-to-hip sensing delays were shorter than foot-to-head, as expected. We used multi-variable output error state-space (MOESP) system identification to estimate foot-ground acceleration as a function of hip- and head-localized sensing, individually and combined. Hip-localized sensors alone provided the best state estimates, which were not improved when fused with head-localized sensors. However, estimates from head-localized sensors improved with higher neck stiffness. Our findings support the hypothesis that hip-localized balance sense improves the speed and accuracy of foot state estimation compared to head-localized sense. The findings also suggest a role of neck muscles for active sensing for balance control: increased neck stiffness through muscle co-contraction can improve the utility of vestibular signals. Our engineering approach provides, to our knowledge, the first quantitative evidence for functional benefits of the LSO balance sense in birds. The findings support notions of control modularity in birds, with preferential vestibular sense for head stability and gaze, and LSO for body balance control,respectively. The findings also suggest advantages for distributed and active sensing for agile locomotion in compliant bipedal robots

A free-energy stable nodal discontinuous Galerkin approximation with summation-by-parts property for the Cahn-Hilliard equation

We present a nodal Discontinuous Galerkin (DG) scheme for the Cahn-Hilliard equation that satisfies the summation-by-parts simultaneous-approximation-term (SBP-SAT) property. The latter permits us to show that the discrete free-energy is bounded, and as a result, the scheme is provably stable. The scheme and the stability proof are presented for general curvilinear three-dimensional hexahedral meshes. We use the Bassi-Rebay 1 (BR1) scheme to compute interface fluxes, and an IMplicit-EXplicit (IMEX) scheme to integrate in time. Lastly, we test the theoretical findings numerically and present examples for two and three-dimensional problems

Internal Structure of Ariebreen, Spitsbergen, from radio-echo sounding data

Ariebreen (77º 01' N, 15º 29' E) is a small valley glacier (ca. 0.36 km2 in August 2007) located at Hornsund, Spitsbergen, Svalbard, ca. 2.5 km to the west of Hornsund Polish Polar Station. Ariebreen, like many other Svalbard glaciers, has experienced a significant recession at least since the 1930s, and most likely since the end of Little Ice Age (LIA) in the early part of the 20th century. Moreover, the thinning rate of western Svalbard glaciers has shown an acceleration during the most recent decades. Ariebreen follows this general retreat pattern, as is shown in another contribution to this workshop (Petlicki et al., 2008). Most investigated glaciers in Hornsund area, in the neighbourhood of Ariebreen, are known to be polythermal (e.g. Hansbreen and Werenskioldbreen, Pälli et al., 2003). It has been suggested (Macheret et al., 1992) that the thinning of polythermal glaciers may result in a switch to cold thermal structure under appropriate conditions. The strong thinning experienced by Ariebreen during the recent decades makes it an ideal candidate to undergo such change. The main aims of this contribution are to understand the internal structure of Ariebreen, in particular, its hydrothermal regime, and to determine whether the glacier is undergoing or has already experienced a transition from polythermal to cold structure. The main tool to accomplish this will be the analysis of radio-echo sounding data

Transforming AdaPT to Ada

This paper describes how the main features of the proposed Ada language extensions intended to support distribution, and offered as possible solutions for Ada9X can be implemented by transformation into standard Ada83. We start by summarizing the features proposed in a paper (Gargaro et al, 1990) which constitutes the definition of the extensions. For convenience we have called the language in its modified form AdaPT which might be interpreted as Ada with partitions. These features were carefully chosen to provide support for the construction of executable modules for execution in nodes of a network of loosely coupled computers, but flexibly configurable for different network architectures and for recovery following failure, or adapting to mode changes. The intention in their design was to provide extensions which would not impact adversely on the normal use of Ada, and would fit well in style and feel with the existing standard. We begin by summarizing the features introduced in AdaPT

Programming in a proposed 9X distributed Ada

The studies of the proposed Ada 9X constructs for distribution, now referred to as AdaPT are reported. The goals for this time period were to revise the chosen example scenario and to begin studying about how the proposed constructs might be implemented. The example scenario chosen is the Submarine Combat Information Center (CIC) developed by IBM for the Navy. The specification provided by IBM was preliminary and had several deficiencies. To address these problems, some changes to the scenario specification were made. Some of the more important changes include: (1) addition of a system database management function; (2) addition of a fourth processing unit to the standard resources; (3) addition of an operator console interface function; and (4) removal of the time synchronization function. To implement the CIC scenario in AdaPT, the decided strategy were publics, partitions, and nodes. The principle purpose for implementing the CIC scenario was to demonstrate how the AdaPT constructs interact with the program structure. While considering ways that the AdaPt constructs might be translated to Ada 83, it was observed that the partition construct could reasonably be modeled as an abstract data type. Although this gives a useful method of modeling partitions, it does not at all address the configuration aspects on the node construct