On the Wilf-Stanley limit of 4231-avoiding permutations and a conjecture of Arratia

We construct a sequence of finite automata that accept subclasses of the class of 4231-avoiding permutations. We thereby show that the Wilf-Stanley limit for the class of 4231-avoiding permutations is bounded below by 9.35. This bound shows that this class has the largest such limit among all classes of permutations avoiding a single permutation of length 4 and refutes the conjecture that the Wilf-Stanley limit of a class of permutations avoiding a single permutation of length k cannot exceed (k-1)^2.Comment: Submitted to Advances in Applied Mathematic

CERN and the Environment

The impact of CERN’s activities on the surrounding environment is carefully monitored by the Organization via a complete environmental monitoring programme, which is defined and run in agreement with the authorities of Switzerland and France. This programme covers both radiological and conventional aspects. So far the environmental impact of CERN was shown to be negligible. In particular, CERN’s radiological impact is a fraction of the variation of the natural exposure at different locations of the surrounding region. As the site of the Organization is on the territory of two countries and straddles the Swiss-French border, the implementation of its environmental policy requires specific procedures and a very transparent communication towards the Host States authorities and the public opinion. This paper reports the official CERN speech delivered for the opening of the international conference Enviroinfo 2004 that was held at CERN in October 2004

Status of the Construction of the First 15 m Long Superconducting Dipole Prototype for the LHC

CERN and INFN are jointly building the first full-size superconducting dipole prototype for the LHC. This magnet, whose construction was launched in spring 1995, is completely manufactured in industry . Its fabrication required the upgrade of the tooling which was used to build three 10-m long prototypes under a previous CERN-INFN Collaboration. The construction is being completed and the cryostate d magnet is expected to be at CERN for testing by the end of 1997. In this paper we discuss the results of the measurements carried out at 4.2 K and 2 K to determine the conductor properties (Ic of wi res and cables, magnetization), as well as the short sample limit. The main features of the coil construction are presented, together with the results of the main fabrication phases. In particular, th e validity of the fabrication techniques is assessed based on the obtained results

Velocity-independent estimation of kinematic attributes in vertical transverse isotropy media using local slopes and predictive painting

© 2016 Society of Exploration Geophysicists. A good seismic velocity model is required for many routine seismic imaging techniques. Velocity model building from seismic data is often labor intensive and time consuming. The process becomes more complicated by taking nonhyperbolic traveltime estimations into account. An alternative to the conventional time-domain imaging algorithms is to use techniques based on the local event slopes, which contain sufficient information about the traveltime moveout for velocity estimation and characterization of the subsurface geologic structures. Given the local slopes, there is no need for a prior knowledge of a velocity model. That is why the term "velocity independent" is commonly used for such techniques. We improved upon and simplified the previous versions of velocity-independent nonhyperbolic approximations for horizontally layered vertical transverse isotropy (VTI) media by removing one order of differentiation with respect to offset from the imaging kinematic attributes. These kinematic attributes are derived in terms of the local event slopes and zero-offset two-way traveltime (TWTT). We proposed the use of predictive painting, which keeps all the attributes curvature independent, to estimate the zero-offset TWTT. The theoretical contents and performance of the proposed approach were evaluated on synthetic and field data examples. We also studied the accuracy of moveout attributes for shifted hyperbola, rational, three-parameter, and acceleration approximations on a synthetic example. Our results show that regardless of the approximation types, NMO velocity estimate has higher accuracy than the nonhyperbolicity attribute. Computational time and accuracy of the inversion of kinematic attributes in VTI media using our approach were compared with routine/conventional multiparameter semblance inversion and with the previous velocityindependent inversion techniques

Integrated Safety and Environment Group: Annual Report 2003

This report summarizes the main activities of the Integrated Safety and Environment (IE) Group of the Safety Commission (TIS) during the year 2003, and the results obtained. The different topics in which the group is active are covered: environment, quality management, safety training and major accidents follow-up

Temporal characteristics of speech: The effect of age and speech style

Aging affects temporal characteristics of speech. It is still a question how these changes occur in different speech styles which require various cognitive skills. In this paper speech rate, articulation rate, and pauses of 20 young and 20 old speakers are analyzed in four speech tyles: spontaneous narrative, narrative recalls, a three-participant conversation, and reading aloud. Results show that age has a significant effect only on speech rate, articulation rate, and frequency of pauses. Speech style has a higher effect on temporal parameters than speakers’ age

Cryogenic and vacuum sectorisation of the LHC arcs

Following the recommendation of the LHC TC of June 20th, 1995 to introduce a separate cryogenic distribution line (QRL), which opened the possibility to have a finer cryogenic and vacuum sectorisation of the LHC machine than the original 8 arcs scheme, a working group was set up to study the implications: technical feasibility, advantages and drawbacks as well as cost of such a sectorisation (DG/DI/LE/dl, 26 July 1995). This report presents the conclusions of the Working Group. In the LHC Conceptual Design Report, ref. CERN/AC/95-05 (LHC), 20 October 1995, the so-called "Yellow Book", a complete cryostat arc (~ 2.9 km) would have to be warmed up in order to replace a defective cryomagnet. Even by coupling the two large refrigerators feeding adjacent arcs at even points to speed up the warm-up and cool down of one arc, the minimum down-time of the machine needed to replace a cryomagnet would be more than a full month (and even 52 days with only one cryoplant). Cryogenic and vacuum sectorisation of an arc into smaller sectors is technically feasible and would allow to reduce the down-times considerably (by one to three weeks with four sectors of 750 m in length, with respectively two or one cryoplants). In addition, sectorisation of the arcs may permit a more flexible quality control and commissioning of the main machine systems, including cold testing of small magnet strings. Sectorisation, described in detail in the following paragraphs, consists essentially of installing several additional cryogenic and vacuum valves as well as some insulation vacuum barriers. Additional cryogenic valves are needed in the return lines of the circuits feeding each half-cell in order to complete the isolation of the cryoline QRL from the machine, allowing intervention (i.e. venting to atmospheric pressure) on machine sectors without affecting the rest of an arc. Secondly, and for the same purpose, special vacuum and cryogenic valves must be installed, at the boundaries of machine sectors, for the circuits not passing through the cryoline QRL. Finally, some additional vacuum barriers must be installed around the magnet cold masses to divide the insulation vacuum of the magnet cryostats into independent sub-sectors, permitting to keep under insulating vacuum the cryogenically floating cold masses, while a sector (or part of it) is warmed up and opened to atmosphere. A reasonable scenario of sectorisation, namely with four 650-750 m long sectors per arc, and each consisting of 3 or 4 insulation vacuum sub-sectors with two to four half-cells, would represent an additional total cost of about 6.6 MCHF for the machine. It is estimated that this capital investment would be paid off by time savings in less than three long unscheduled interventions such as the change of a cryomagnet