Stability of Coalescence Hidden variable Fractal Interpolation Surfaces

In the present paper, the stability of Coalescence Hidden variable Fractal Interpolation Surfaces(CHFIS) is established. The estimates on error in approximation of the data generating function by CHFIS are found when there is a perturbation in independent, dependent and hidden variables. It is proved that any small perturbation in any of the variables of generalized interpolation data results in only small perturbation of CHFIS. Our results are likely to be useful in investigations of texture of surfaces arising from the simulation of surfaces of rocks, sea surfaces, clouds and similar natural objects wherein the generating function depends on more than one variable

Predicting total reaction cross sections for nucleon-nucleus scattering

Nucleon total reaction and neutron total cross sections to 300 MeV for 12C and 208Pb, and for 65 MeV spanning the mass range, are predicted using coordinate space optical potentials formed by full folding of effective nucleon-nucleon interactions with realistic nuclear ground state densities. Good to excellent agreement is found with existing data.Comment: 10 pages, 4 figure

Inland Waterway Operational Model & Simulation Along the Ohio River

The inland waterway system of the U.S. is a vital network for transporting key goods and commodities from the point of production to manufacturers and consumers. Shipping materials via the inland waterways is arguably the most economical and environmentally friendly option (compared to hauling freight by trains or railways). Despite the advantages the inland waterways enjoys over competing modes, key infrastructure – such as locks and dams, which help to control water levels on a number of rivers and make navigation possible – is declining. Limited funds have been allocated to make the necessary repairs to lock and dam facilities. Over the past 10 years Inland Waterways Trust Fund resources (which historically funded maintenance and improvement projects) has steadily declined. Locks and dams are of particular importance, because they assist in the maintenance of navigable depths on many of the major inland waterways (Ohio River, Upper Mississippi River, Tennessee River). To better understand the operation of the inland waterway system, this report examines a portion of the Ohio River (extending from Markland Locks and Dam to Lock 53). The specific focus is to determine what delays barge tows as they attempt to lock through these critical facilities. The Ohio River is a particularly important study area. In many ways it is representative of the conditions present throughout the inland waterways system. The average age of the lock and dam facilities exceed 50 years along our study segment. Most of these facilities are operating beyond their intended design life. As locks age, they increasingly demand more scheduled and unscheduled maintenance activities. Maintenance activities often require temporarily shuttering a lock chamber and diverting traffic through another onsite chamber (often of smaller capacity). All of the facilities included in the research area have two lock chambers ‐ thus, if one goes down for maintenance all vessels are diverted through the second chamber. In many cases this situation can produce extensive delays, which precludes cargo from reaching the destination in a timely manner. Recently, the aggregate number of hours that shippers and carriers lose due to delays has escalated. Although the U.S. Army Corps of Engineers – the agency responsible for the management and oversight of locks and dams – has worked to keep traffic flowing on the river, tightening budgets hamper efforts. For shippers and carriers to make informed decisions about when and where to deploy freight on the river, they require knowledge that illuminates factors that are most significant in affecting transit times. In particular this applies to certain conditions that are likely to create delays at lock and dam facilities. The purpose of this report is to 1) develop a comprehensive profile of the Ohio River that provides an overview of how it is integral to U.S. economic security 2) identify salient river characteristics or externally‐driven variables that influence the amount of water flowing through the main channel which consequently impacts vessels’ capacity to navigate 3) use this information (along with a 10‐year data set encompassing over 600,000 observations) to develop an Inland Waterways Operational Model (IWOM). The IWOM objective is to provide the U.S. Army Corps of Engineers, shippers, carriers, and other interested parties with access to8 a robust method that aids in the prediction of where and when conditions will arise on the river that have the potential to significantly impact lockage times and queue times (i.e. how long a vessel has to wait after it arrives at a facility to lock through). After qualitatively reviewing different features of the river system that affect vessel traffic, this report outlines two approaches to modeling inland waterway system behavior – a discrete event simulation (DES) model which uses proprietary software, and the IWOM. Although the DES produced robust findings that aligned with the historical data (because it relies upon proprietary software), it does not offer an ideal platform to distribute knowledge to stakeholders. Indeed, this is the major drawback of the DES given a critical objective of this project is to generate usable information for key stakeholders who are involved with inland waterway operations. Conversely, the IWOM is a preferable option given it relies on statistical analysis – in this sense, it is more of an open‐source solution. The IWOM uses linear regression to determine key variables affecting variation in lockage time. The final model accounts for over two‐thirds of the observed variation in lockage times from 2002‐2012, which is our study period. Practically, this means that the difference between predicted values and observed delay times is significantly less than how the delays vary around the composite average seen in the river system (R2 = 0.69). The IWOM confirms that variations in river conditions significantly affect vessel travel times. For example, river discharge ‐ the direction a vessel moves up or down a river ‐ meaningfully influences lockage times. The freight amount a vessel carries, which is represented by the amount of draft and newness of a vessel, influences lockage times. Larger vessels with more draft tend to wait longer and take longer to complete their lockage. The IWOM is less successful at predicting delay times. Because there is greater instability in this data only a modest amount of variation is explained by the model (R2 = 0.23). This, in turn, partly reflects in spillover from one vessel to the next that is difficult for the simulation to impose and account for therefore requiring additional logic. Once completed, the IWOM was used to parameterize a simulation model. This provided a graphical representation of vessels moving along the river. Users have the capability of adjusting the effects of different variables to anticipate how the system may react, and what changes in vessel traffic patterns emerge. This information will be of great use for stakeholders wanting to gain a better understanding of what conditions lockage times will increase or decrease, why delays emerge, and consequently how these impact traffic flows on the river. In programming a simulation model, users are able to visualize and intuit what causes vessel travel times to vary. Although the regression model accomplishes this, for many users this would prove unwieldy and difficult to grasp beyond a conceptual, abstract level. Matching up regression results with a visual counterpart lets users gain immediate and intimate knowledge of river and vessel behavior – this in turn can positively affect shipper and carrier modal choices. The report concludes with some recommendations for IWOM implementation and thoughts on future research needs. Also discussed are the implications results from the present study have for improving our ability to safely, securely, and swiftly move freight on the inland waterways network

New stopping criteria for segmenting DNA sequences

We propose a solution on the stopping criterion in segmenting inhomogeneous DNA sequences with complex statistical patterns. This new stopping criterion is based on Bayesian Information Criterion (BIC) in the model selection framework. When this stopping criterion is applied to a left telomere sequence of yeast Saccharomyces cerevisiae and the complete genome sequence of bacterium Escherichia coli, borders of biologically meaningful units were identified (e.g. subtelomeric units, replication origin, and replication terminus), and a more reasonable number of domains was obtained. We also introduce a measure called segmentation strength which can be used to control the delineation of large domains. The relationship between the average domain size and the threshold of segmentation strength is determined for several genome sequences.Comment: 4 pages, 4 figures, Physical Review Letters, to appea

Efficient optical quantum information processing

Quantum information offers the promise of being able to perform certain communication and computation tasks that cannot be done with conventional information technology (IT). Optical Quantum Information Processing (QIP) holds particular appeal, since it offers the prospect of communicating and computing with the same type of qubit. Linear optical techniques have been shown to be scalable, but the corresponding quantum computing circuits need many auxiliary resources. Here we present an alternative approach to optical QIP, based on the use of weak cross-Kerr nonlinearities and homodyne measurements. We show how this approach provides the fundamental building blocks for highly efficient non-absorbing single photon number resolving detectors, two qubit parity detectors, Bell state measurements and finally near deterministic control-not (CNOT) gates. These are essential QIP devicesComment: Accepted to the Journal of optics B special issue on optical quantum computation; References update

Burst dynamics during drainage displacements in porous media: Simulations and experiments

We investigate the burst dynamics during drainage going from low to high injection rate at various fluid viscosities. The bursts are identified as pressure drops in the pressure signal across the system. We find that the statistical distribution of pressure drops scales according to other systems exhibiting self-organized criticality. The pressure signal was calculated by a network model that properly simulates drainage displacements. We compare our results with corresponding experiments.Comment: 7 pages, 4 figures. Submitted to Europhys. Let

Amplification by stochastic interference

A new method is introduced to obtain a strong signal by the interference of weak signals in noisy channels. The method is based on the interference of 1/f noise from parallel channels. One realization of stochastic interference is the auditory nervous system. Stochastic interference may have broad potential applications in the information transmission by parallel noisy channels

Trajectory Model Validation Using Newly Developed Altitude-Controlled Balloons During the International Consortium for Atmospheric Research on Transport and Transformations 2004 Campaign

During the summer of 2004, five altitude-controlled tracking balloons were flown as part of the International Consortium for Atmospheric Research on Transport and Transformations (ICARTT) campaign. These Controlled Meteorological (CMET) balloons, newly developed at the University of Massachusetts, are notable for their light weight (∼1 kg mass), efficient altitude control, case of launch, long-duration flight capability, and ability to perform repeated quasi-Lagrangian soundings. The balloons were embedded in urban plumes from New York and Boston which they tracked over New England, eastern Canada, and the Atlantic Ocean while maintaining a nearly constant altitude. The flights ranged from 10 to 111 hours and covered a maximum distance of 3000 km. Balloon flight tracks are used here to assess the accuracy of trajectory models during intensive aircraft sampling periods. A new method is presented for increasing the number of available reference trajectories by dividing the balloon flights into shorter segments for statistical analysis. For trajectory durations between 2 and 12 hours, mean trajectory errors are found to be approximately 26% and 34% of the flight distance for ECMWF-based and GFS-based trajectories, respectively. Anomalously large model errors observed during three of the flights are found to be the result of a narrow low-level jet (15 July) and synoptic-scale flow patterns (9 and 10 August). The results from this study should be useful to researchers evaluating the performance of trajectory models and chemical transport models during the ICARTT campaign. Complete CMET balloon and model trajectory data sets are available as a supplement to this paper

Interatomic Coulombic Decay following Photoionization of the Helium Dimer: Observation of Vibrational Structure

Using synchrotron radiation we simultaneously ionize and excite one helium atom of a helium dimer (He_2) in a shakeup process. The populated states of the dimer ion (i.e. He^[*+](n = 2; 3)-He) are found to deexcite via interatomic coulombic decay. This leads to the emission of a second electron from the neutral site and a subsequent coulomb explosion. In this letter we present a measurement of the momenta of fragments that are created during this reaction. The electron energy distribution and the kinetic energy release of the two He^+ ions show pronounced oscillations which we attribute to the structure of the vibrational wave function of the dimer ion.Comment: 8 pages, 5 figure