ON THE COMPARISON OF TIME SERIES USING SUBSAMPLING

In this paper we propose a procedure based on the subsampling techniques for the comparison of stationary time series that are not necessarily independent. We study a test based on the Euclidean distance between the autocorrelation functions of two series. Consistency of the proposed method is established. We present a Monte Carlo study with the size and the power of the proposed test.

Most Probable Failures in LHC Magnets and Time Constants of their Effects on the Beam.

During the LHC operation, energies up to 360 MJ will be stored in each proton beam and over 10 GJ in the main electrical circuits. With such high energies, beam losses can quickly lead to important equipment damage. The Machine Protection Systems have been designed to provide reliable protection of the LHC through detection of the failures leading to beam losses and fast dumping of the beams. In order to determine the protection strategies, it is important to know the time constants of the failure effects on the beam. In this report, we give an estimation of the time constants of quenches and powering failures in LHC magnets. The most critical failures are powering failures in certain normal conducting circuits, leading to relevant effects on the beam in ~1 ms. The failures on super conducting magnets leading to fastest losses are quenches. In this case, the effects on the beam can be signficant ~10 ms after the quench occurs

Rapid bridge deck joint repair investigation - Phase III

Accelerated Bridge Construction (ABC) technologies are changing the ways State Departments of Transportation (DOTs) do business. Subsequently, a three-phase project on the Rapid Bridge Deck Joint Repair Investigation is originated with the Iowa DOT. Phase I of this project focused on documenting the current means and methods of bridge expansion joint maintenance and replacement, and then identifying improvements. Based on the findings from Phase I, Phase II focused on the concept development. It was decided that a desirable approach would be to develop a design to move the joint away from the bridge deck at the face of the abutment to the approach slab that acts as a transition between roadway pavement and the previously mentioned bridge deck. By using this concept, a more effective joint can be created, where possible deicing chemical laden water leakage on the substructure components is no longer a concern for deterioration and its construction time can be comparable to that required for traditional joint replacements. Phase III is tasked with the further development of this concept, the deck over backwall concept. The research team proposed various joint detailing options taking numerous factors into account. With this information, the Iowa DOT developed a more detailed joint considering their construction practices, experiences, and preferences. Full-scale finite element (FE) models of two different bridges were realized. These models were analyzed with various loading conditions from dead loads, temperature loading, and live loads which corresponds to various truck loading conditions. Both models were validated using the original drawing plans and the American Association of State Highway and Transportation Officials (AASHTO) Specifications providing deflection limits for vehicular bridges in the absence of other criteria. The impact of the deck over backwall concept on the existing bridge elements was studied with the FE models alongside a parametric study of various bridge skew angles. The concept along with the approach slab were modeled in the FE models. Results show an increment in bearing loads due to the dead loads and live loads alongside relevant deflection values and stress levels at certain points of interest across the new joint and approach slab. A cost estimate of different types of joints including the deck over backwall concept was developed. An initial estimate of the construction cost of the concept was realized to be used in the overall cost estimate. Results show that the deck over backwall concept over a bridge service life of 25 years constantly ranked 3th or 4th out of the nine types of joints that were considered. Over a bridge service life of 50 years, the concept produced the lowest cost in all possible combinations of inflation rates and fluctuations in installation cost and joint service life. In average, a break-even point (BEP) of 44 years was determined with a 2% interest rate and lowers as the interest rate is increased. An experimental investigation plan was realized with the Iowa DOT joint. Test results will be compared and correlated with the FE models. A plan for construction observation and post-construction testing was developed with an instrumentation plan and various real-life truck loading cases to be correlated with the FE models. Implementation of the deck over backwall concept and the post-construction plan is expected to be conducted in a future Iowa DOT construction season. With the results obtained from the FE models and, in the future, with the experimental investigation and the post-construction testing, the Iowa DOT can confidently design and further develop the deck over backwall concept

Contention Resolution Queues for Massive Machine Type Communications in LTE

In this paper, we address the challenge of high device density performing simultaneous transmissions by proposing and evaluating a solution to efficiently handle the initial access contention for highly dense LTE networks. We present the implementation of a tree-splitting algorithm in the access procedure of LTE, which is capable to cope with high number of simultaneous arrivals. Based on simulations we show a feasible implementation capable to achieve, under certain network configuration conditions, up to 85% average access delay reduction and 40% reduction on the average energy consumption, while maintaining a consistently low blocking probability, regardless of the number of initial simultaneous access attempts

Orbital-Free Molecular Dynamics Simulations of Melting in Na8 and Na20: Melting in Steps

The melting-like transitions of Na8 and Na20 are investigated by ab initio constant energy molecular dynamics simulations, using a variant of the Car-Parrinello method which employs an explicit electronic kinetic energy functional of the density, thus avoiding the use of one-particle orbitals. Several melting indicators are evaluated in order to determine the nature of the various transitions, and compared with other simulations. Both Na8 and Na20 melt over a wide temperature range. For Na8, a transition is observed to begin at approx. 110 K, between a rigid phase and a phase involving isomerizations between the different permutational isomers of the ground state structure. The ``liquid'' phase is completely established at approx. 220 K. For Na20, two transitions are observed: the first, at approx. 110 K, is associated with isomerization transitions between those permutational isomers of the ground state structure which are obtained by interchanging the positions of the surface-like atoms; the second, at approx. 160 K, involves a structural transition from the ground state isomer to a new set of isomers with the surface molten. The cluster is completely ``liquid'' at approx. 220 K.Comment: Revised version, accepted for publication in J. Chem. Phys. The changes include longer simulations for the Na20 microcluster, a more complete comparison to previous theoretical results, and the discussion of some technical details of the method applie

Approximation of supply curves

In this note, we illustrate the computation of the approximation of the supply curves using a one-step basis. We derive the expression for the L2 approximation and propose a procedure for the selection of nodes of the approximation. We illustrate the use of this approach with three large sets of bid curves from European electricity markets

Clustering time series by linear dependency

We present a new way to find clusters in large vectors of time series by using a measure of similarity between two time series, the generalized cross correlation. This measure compares the determinant of the correlation matrix until some lag k of the bivariate vector with those of the two univariate time series. A matrix of similarities among the series based on this measure is used as input of a clustering algorithm. The procedure is automatic, can be applied to large data sets and it is useful to find groups in dynamic factor models. The cluster method is illustrated with some Monte Carlo experiments and a real data example