Abstract

Abstract
The Unit Commitment Problem (UCP) is a well-known combinatorial optimization problem in power systems. The main goal in the UCP is to schedule a subset of a given group of electrical power generating units and also to determine their production output in order to meet energy demands at minimum cost. In addition, a set of technological and operational constraints must be satisfied. A large variety of optimization methods addressing the UCP is available in the literature. This panoply of methods includes exact methods (such as dynamic programming, branch-and-bound) and heuristic methods (tabu search, simulated annealing, particle swarm, genetic algorithms). This paper proposes two non-traditional formulations. First, the UCP is formulated as a mixed-integer optimal control problem with both binary-valued control variables and real-valued control variables. Then, the problem is formulated as a switching time dynamic optimization problem involving only real-valued controls.

Abstract
We present the first optical observation of the microquasar SS 433 at sub-milliarcsecond (mas) scale obtained with the GRAVITY instrument on the Very Large Telescope interferometer (VLTI). The 3.5-h exposure reveals a rich K-band spectrum dominated by hydrogen Br gamma and He i lines, as well as (red-shifted) emission lines coming from the jets. The K-band-continuum-emitting region is dominated by a marginally resolved point source (<1 mas) embedded inside a diffuse background accounting for 10% of the total flux. The jet line positions agree well with the ones expected from the jet kinematic model, an interpretation also supported by the consistent sign (i.e., negative/positive for the receding/approaching jet component) of the phase shifts observed in the lines. The significant visibility drop across the jet lines, together with the small and nearly identical phases for all baselines, point toward a jet that is off set by less than 0.5 mas from the continuum source and resolved in the direction of propagation, with a typical size of 2 mas. The jet position angle of similar to 80 degrees is consistent with the expected one at the observation date. Jet emission so close to the central binary system would suggest that line locking, if relevant to explain the amplitude and stability of the 0.26c jet velocity, operates on elements heavier than hydrogen. The Br gamma profile is broad and double peaked. It is better resolved than the continuum and the change of the phase signal sign across the line on all baselines suggests an East-West-oriented geometry similar to the jet direction and supporting a (polar) disk wind origin.

Abstract
Software business continues to expand globally, highly motivated by the reachability of the Internet and possibilities of Cloud Computing. While widely adopted, development for the cloud has some intrinsic properties to it, making it complex to any newcomer. This research is capturing those intricacies using a pattern catalog, with this paper contributing with three of those patterns: Messaging System, a message bus for abstracting service placement in a cluster and orchestrating messages between multiple services; Preemptive Logging, a design principle where services and servers continuously output relevant information to log files, making them available for later debugging failures; and Log Aggregation, a technique to aggregate logs from multiple services and servers in a centralized location, which indexes and provides them in a queryable, user friendly format. These patterns are useful for anyone designing software for the cloud, either to guide or validate their design decisions. © 2017 Copyright is held by the owner/author(s).

Abstract
Autonomous underwater vehicles (AUVs) are increasingly being used to perform search operations but its capabilities are limited by the efficiency of the planning process. The objective of the paper is to propose new survey planning methods for AUVs. In particular, the problem of multi-objective search mission planning with an AUV navigating in known or unknown 3D environments is studied. The vehicle should completely cover the operating area while maximizing the probability of detecting the targets and minimizing the required energy and time to complete the mission. The approach presented here differs from other CPP methods in that paths for coverage are generated based on a coverage map that is actively maintained as the vehicle executed its mission. Our replanning approach borrows ideas from case-based reasoning (CBR) in which old problem and solution information helps solve a new problem. The resulting combination takes advantage of both paradigms where our evolutionary approach in conjunction with an artificial neural network (ANN), presented earlier, delivers robustness and adaptive learning while the case-based component speeds up the replanning process. The experiments show that the online algorithm was able to successfully replan missions in varied scenarios and guarantee full area coverage while minimizing resource consumption.

Abstract
The most widely used resiliency approach today, based on Checkpoint and Restart (C/R) recovery, is not expected to remain viable in the presence of the accelerated fault and error rates in future Exascale-class systems. In this paper, we introduce a series of pragma directives and the corresponding source-to-source transformations that are designed to convey to a compiler, and ultimately a fault-aware run-time system, key information about the tolerance to memory errors in selected sections of an application. These directives, implemented in the ROSE compiler infrastructure, convey information about storage mapping and error tolerance but also amelioration and recovery using externally provided functions and multi-threading. We present preliminary results of the use of a subset of these directives for a simple implementation of the conjugate-gradient numerical solver in the presence of uncorrected memory errors, showing that it is possible to implement simple recovery strategies with very low programmer effort and execution time overhead. © Springer International Publishing AG 2017.