The Dependence of the Field Decay on the Powering History of the LHC Superconducting Dipole Magnets

The decay of the allowed multipoles in the Large Hadron Collider (LHC) dipoles is expected to perturb the beam stability during the particle injection. The decay amplitude is largely affected by the powering history of the magnet and is particularly dependent on the pre-cycle flat-top current and duration as well as the pre-injection preparation duration. With possible prospects of having different genres of cycles during the LHC operation, the powering history effect must be taken into account in the Field Description Model for the LHC and must hence be corrected during machine operation. This paper presents the results of the modelling of this phenomenon

Revised submission for MOF 2.0 query / views / transformations RFP.

This submission presents the QVT-Partners proposal for the MOF 2.0 QVT standard. The proposal consists of a number of key ingredients which we briefly discuss in this section. -Specification and implementation: A common scenario in the development of any artifact is to first create a specification of the form and behaviour of the the artifact, and then realise an implementation which satisfies the specification. The specification is characterised by a lack of implementation details, but having a close correspondence to the requirements; conversely an implementation may lack close correspondence to the requirements. This submission maintains this important distinction. Relations provide a specification oriented view of the relationship between models and are specified in a language that can be easily understood. They say what it means to translate between several models but without saying precisely how the translation is achieved. Those details are realised by mappings which characterise the means by which models are translated. It should be noted though, that while the mappings language is rich enough to provide an implementation of relations it also manages to maintain a requirements oriented focus. This may give rise to a scenario where developers prefer to omit relations and directly define mappings. -Scalability and reuse: Decomposition is a key approach to managing complexity. This submission provides a number of composition mechanisms whereby relations and mappings can be composed to form more complex specifications. These mechanisms also aid reuse since mappings and relations can be treated as reusable components which are composed for specific contexts. -Usability: Diagrammatic notations have been important to the success of many OMG standards. This proposal presents a diagrammatic notation which is an extension of collaboration object diagrams and is therefore familiar to many end users. A criticism often levelled at diagrammatic notations is their scalability. This submission also presents a textual syntax, constructs of the diagrammatic notations are closely aligned with its textual counterpart. Considering the domains of relations and mappings at the generic type level is often too limiting. Instead it often is specific-types of things that are of interest. This submission uses patterns to describe the domains of both relations and mappings. Patterns are a means of succinctly describing specific-types of model elements and enable domains of interest to be rapidly stated with ease. -Semantic soundness: By definition a standard should give rise to consistency across differing implementations. It is important that an end user can get the same results on two different implementations. For this reason, this submission goes to some effort to ensure that all the constructs have a well-defined semantic basis. This is achieved by treating the submission in two parts. The infrastructure part has a small number of constructs which can be easily and consistently understood from informal descriptions (although a mathematical semantics is given in Appendix B for the sake of completeness and rigour). The superstructure part uses the infrastructure as its semantic basis and defines the syntax that the end user deals with. The relationship between the superstructure and the infrastructure is expressed as a translation

The Field Description Model for the LHC Quadrupole Superconducting Magnets

The LHC control system requires an accurate forecast of the magnetic field and the multipole field errors to reduce the burden on the beam-based feed-back. The Field Description for the LHC (FIDEL) is the core of this forecast system and is based on the identification and physical decomposition of the effects that contribute to the total field in the magnet apertures. The effects are quantified using the data obtained from series magnetic measurements at CERN and they are consequently modelled empirically or theoretically depending on the complexity of the physical phenomena. This paper presents a description of the methodology used to model the field of the LHC magnets particularly focusing on the results obtained for the LHC main quadrupoles (MQ) and insertion region wide aperture quadrupoles (MQY)

Measurement and Modeling of Magnetic Hysteresis in the LHC Superconducting Correctors

The Large Hadron Collider, now under construction at CERN, relies heavily on superconducting magnets for its optics layout: besides the main magnets, almost all the correcting magnets are superconducting. Along with clear advantages, this brings about complications due to the effects of persistent currents in the superconducting filaments. Corrector magnets that trim key beam parameters or compensate field errors of the main magnets (among others those due to hysteresis), are in their turn hysteretic. In this paper we present the measured magnetic hysteresis and its possible influence on accelerator operation, with particular reference to realtime compensation of dynamic effects in the main magnets, and reproducibility issues between runs. The modeling strategy as a function of the required accuracy is discussed, and two examples are presented

Dependence of the Static and Dynamic Field Quality of the LHC Superconducting Dipole Magnets on the Pre-Cycle Ramp Rate

The allowed multipoles in the Large Hadron Collider (LHC) superconducting dipole magnets decay whilst on a constant current plateau. It is known that the decay amplitude is largely affected by the powering history of the magnet, and particularly by the pre-cycle flat top current and duration and the pre-injection preparation duration. Recently, it was observed that the decay amplitude is also highly dependent on the pre-cycle ramp rate, which has an indirect effect also on the sample of data taken at constant field along the magnet loadlines. This is an important consideration to be included in the Field Description for the LHC (FiDeL), to cope with the difference between the test procedure followed for series tests and the expected cycles during the machine operation. This paper presents the results of the measurements performed to investigate this phenomenon and describes the method included in FiDeL to represent this dependence

An investigation into the use of CALNN capped gold nanoparticles for improving microwave heating

The use of microwaves for both therapeutic and diagnostic applications has become an accepted alternative in the clinics. For diagnostics, gold (Au) nanoparticles have been used for imaging tumour vasculature and also served as potential diagnostic markers for cancer. [1] In high-frequency therapeutic applications, two different treatments exist; hyperthermia and ablation. [2] In hyperthermia, the tumour tissue is heated to supra-physiological temperatures, making it more susceptible to traditional treatment methods such as chemotherapy and radiotherapy. This type of treatment could be administered externally. However, there still remains a challenge to focus the heating to particular areas which need to be treated, while avoiding unwanted hotspots. To date, numerous methods have been used to focus the heat from different antennas. A novel technique which is being investigated is the use of nanoparticles to improve focusing and thus achieve better localised heating effect. A previous study by Cardinal et al. [3] showed that at RF-frequencies, remarkable improvements resulted from using Au nanoparticles. In this work, the use of CALNN peptide capped Au nanoparticles for the focusing of microwaves at 2.45 GHz is investigated. The CALNN capped Au nanoparticles were prepared as described elsewhere. [4] Au nanoparticles were added to tissue mimicking solutions (such as muscle, liver or fat) to compare their dielectric properties with the those of the control (without Au nanoparticles). The frequency range investigated was from 400 MHz to 20 GHz. During this study, various concentrations, particle sizes and shapes of Au nanoparticles were considered. The study also investigated the heating rates of the pseudo-biological tissue samples and how these varied with the addition of the nanoparticles. The outcome of this study will determine the viability of using CALNN capped Au nanoparticles to assist in the focusing of microwave radiation during microwave hyperthermia

A pattern based approach to defining the dynamic infrastructure of UML 2.0.

The 2U Consortium has recently submitted a proposal for the definition of the UML 2.0 infrastructure. This uses an innovative technique of rapidly “stamping out” the definition using a small number of patterns commonly found in software architecture. The patterns, their instantiation, and any further language details are described using precise class diagrams and OCL, this enables the definition to be easily understood. The main focus of the 2U approach is on the static part of the definition. A further concern when modelling software, using languages such as the UML, is describing the dynamic behaviour of the system over time. The contribution of this paper is to provide a template that can be used to “stamp out” the dynamic part of the UML 2.0 infrastructure. We argue for the suitability of the dynamic template because it makes little commitment to concrete abstractions and can, therefore, be used to support a broad spectrum of behavioural languages

Molecular crystallization inhibitors for salt damage control in porous materials. An overview

The use of inhibition chemicals holds the prospect of an efficient strategy to control crystallization in porous materials, thereby potentially contributing to the prevention or mitigation of the salt decay phenomenon in modern as well as historical building materials in a more sustainable manner. In this review, we first provide an essential background on the mechanism of salt crystallization and on the factors influencing this phenomenon; next, we illustrate the mechanism at the basis of the action of crystal growth inhibitors, and critically discuss the major advances in the development of different families of inhibitors, particularly focusing on their influence on salt transport and crystallization within the structure of porous media. Specifically, correlations between the crystallization inhibition processes in porous materials and variables, such as porous substrate composition and properties, contaminant salt type and concentrations, microclimatic conditions, inhibiting solution concentration and properties, and application methods, will be highlighted. Environmental aspects, limitations, and problems associated with some inhibition chemicals are also taken into account. Finally, a survey and a discussion on the most representative experimental techniques and instrumentation available to assess qualitatively and quantitatively the inhibitor effectiveness, as well as recently developed modelling tools are given out

Unambiguous UML submission to UML 2 infrastructure RFP (ad/00-09-01).

This is a response to the UML 2.0 Request for Proposals on Infrastructure (ad/00-09-01). We propose an architecture for the definition of UML 2.0 which supports the layered and extensible definition of UML as a family of languages, and depends on the use of package extension (composition) and package template mechanisms in the metamodelling language. This submission defines that architecture and populates it with the definition of a core foundation for the definition of structural and behavioural modelling constructs for UML. Chapter 3 (“Language Architecture”) identifies all those parts of the architecture defined in any given version of this document