User Evaluation of Advanced Interaction Features for a Computer-Assisted Translation Workbench

This paper reports on the results of a user satisfaction survey carried out among 16 translators using a new computer-assisted translation workbench. Participants were asked to provide feedback after performing different post-editing tasks on different configurations of the workbench, using different features and tools. Resulting from the feedback provided, we report on the utility of each of the features, identifying new ways of implementing them according to the users’ suggestions

Experimental validation of a novel compact focusing scheme for future energy-frontier linear lepton colliders.

A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed in 2001 [P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)]. This scheme has many advantageous properties over previously studied focusing schemes, including being significantly shorter for a given energy and having a significantly better energy bandwidth. Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of such a scheme by demonstrating the demagnification of a 1.3 GeVelectron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider

The Compact Linear Collider (CLIC) - 2018 Summary Report

The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear $e^+e^-$ collider under development at CERN. Following the CLIC conceptual design published in 2012, this report provides an overview of the CLIC project, its current status, and future developments. It presents the CLIC physics potential and reports on design, technology, and implementation aspects of the accelerator and the detector. CLIC is foreseen to be built and operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV, respectively. CLIC uses a two-beam acceleration scheme, in which 12 GHz accelerating structures are powered via a high-current drive beam. For the first stage, an alternative with X-band klystron powering is also considered. CLIC accelerator optimisation, technical developments and system tests have resulted in an increased energy efficiency (power around 170 MW) for the 380 GeV stage, together with a reduced cost estimate at the level of 6 billion CHF. The detector concept has been refined using improved software tools. Significant progress has been made on detector technology developments for the tracking and calorimetry systems. A wide range of CLIC physics studies has been conducted, both through full detector simulations and parametric studies, together providing a broad overview of the CLIC physics potential. Each of the three energy stages adds cornerstones of the full CLIC physics programme, such as Higgs width and couplings, top-quark properties, Higgs self-coupling, direct searches, and many precision electroweak measurements. The interpretation of the combined results gives crucial and accurate insight into new physics, largely complementary to LHC and HL-LHC. The construction of the first CLIC energy stage could start by 2026. First beams would be available by 2035, marking the beginning of a broad CLIC physics programme spanning 25-30 years

Investigation of the time evolution of the hump frequency observed at the LHC run 2010

Since the LHC started operation, some unknown source is causing an interference in the beams, leading to a vertical oscillation of the order of the micrometer. It can be observed in the tune spectrum where a sort of unexpected broad-band structure so-called hump arises. It varies in frequency, and can cause emittance blow-up and luminosity loss when it approaches the beam tunes [1]. The transverse feedback has been used to mitigate this effect but the source of this perturbation has not been identified yet [2]. One of the observed characteristics of the hump is that the time evolution of the hump frequency, normally slowly varying with time, sometimes shows abrupt changes. These sudden variations of the hump frequency temporal evolution have been investigated in order to identify possible correlations with external factors or actions on any system of the machine. The data adquired with the tune measurement system (BBQ) have been systematically analysed for a long period of the LHC operation (from March to September 2010), and the results are presented in this note

On some recent advances on stabilization for hyperbolic equations

International audienceThe purpose of these Notes is to present some recent advances on stabilization for wave-like equations together with some well-known methods of stabilization. This course will give several references on the subject but do not pretend to exhaustivity. The spirit of these Notes is more that of a research monograph. We aim to give a simplified overview of some aspects of stabilization, on the point of view of energy methods, and insist on some of the methodological approaches developed recently.We will focus on nonlinear stabilization, memory-damping and indirect stabilization of coupled PDE's and present recent methods and results. Energy methods have the advantage to handle and deal with physical quantities and properties of the models under consideration. For nonlinear stabilization, our purpose is to present the optimal-weight convexity method introduced in (Alabau- Boussouira, Appl. Math. Optim. 51(1):61-105, 2005; Alabau-Boussouira, J. Differ. Equat. 248:1473-1517, 2010) which provides a whole methodology to establish easy computable energy decay rates which are optimal or quasi-optimal, and works for finite as well as infinite dimensions and allow to treat, in a unified way different PDE's, as well as different types of dampings: localized, boundary. Another important feature is that the upper estimates can be completed by lower energy estimates for several examples, and these lower estimates can be compared to the upper ones. Optimality is proved in finite dimensions and in particular for one-dimensional semi-discretized wave-like PDE's. These results are obtained through energy comparison principles (Alabau-Boussouira, J. Differ. Equat. 248: 1473-1517, 2010), which are, to our knowledge, new. This methodology can be extended to the infinite dimensional setting thanks to still energy comparison principles supplemented by interpolation techniques. The optimal-weight convexity method is presented with two approaches: a direct and an indirect one. The first approach is based on the multiplier method and requires the assumptions of the multiplier method on the zone of localization of the feedback. The second one is based on an indirect argument, namely that the solutions of the corresponding undamped systems satisfy an observability inequality, the observation zone corresponding to the damped zone for the damped system. The advantage is that, this observability inequality holds under the sharper optimal Geometric Control Condition of Bardos et al. (SIAM J. Contr. Optim. 30:1024-1065, 1992). The optimal-weight convexity method also extends to the case memory-damping, for which the damping effects are nonlocal, and leads to nonautonomous evolution equations. We will only state the results in this latter case. Indirect stabilization of coupled systems have received a lot of attention recently. This subject concerns stabilization questions for coupled PDE's with a reduced number of feedbacks. In practice, it is often not possible to control all the components of the vector state, either because of technological limitations or cost reasons. From the mathematical point of view, this means that some equations of the coupled system are not directly stabilized. This generates mathematical difficulties, which requires to introduce new tools to study such questions. In particular, it is important to understand how stabilization may be transferred from the damped equations to the undamped ones. We present several recent results of polynomial decay for smooth initial data. These results are based on energy methods, a nondifferential integral inequality introduced in (Alabau, Compt. Rendus Acad. Sci. Paris I 328:1015-1020, 1999) [see also (Alabau-Boussouira, SIAMJ. Contr. Optim. 41(2):511-541, 2002; Alabau et al. J. Evol. Equat. 2:127-150, 2002)] and coercivity properties due to the coupling operators

Aperture measurements in the LHC interaction regions

The aperture of the LHC interaction regions is crucial for the LHC performance because it determines the smallest achievable β*. The aperture has been measured at top energy for different energies and optics, following optimized procedure to allow safe measurements at high energy. In this paper, the aperture measurements, whose results determined the LHC operational configurations in 2011 and 2012, are presented

LHC Aperture Measurements

The mechanical aperture of the Large Hadron Collider (LHC) is a critical parameter for the operation of the machine due to the high stored beam intensities in the superconducting environment. Betatron and momentum apertures must be therefore precisely measured and optimised. In this paper, we present the results of beam-based measurements of the LHC aperture. The experimental results are compared with the expectations from the as-built model of the LHC aperture, taking into account the optics imperfections of the superconducting magnets. The impact of these measurements on various aspects of the LHC operation are also discussed