Embarrassingly Parallel Search

International audienceWe propose the Embarrassingly Parallel Search, a simple and efficient method for solving constraint programming problems in parallel. We split the initial problem into a huge number of independent subproblems and solve them with available workers (i.e., cores of machines). The decomposition into subproblems is computed by selecting a subset of variables and by enumerating the combinations of values of these variables that are not detected inconsistent by the propagation mechanism of a CP Solver. The experiments on satisfaction problems and on optimization problems suggest that generating between thirty and one hundred subproblems per worker leads to a good scalability. We show that our method is quite competitive with the work stealing approach and able to solve some classical problems at the maximum capacity of the multi-core machines. Thanks to it, a user can parallelize the resolution of its problem without modifying the solver or writing any parallel source code and can easily replay the resolution of a problem

Effect of Boundary Conditions on the Behavior of Stiffened and Un-Stiffened Cylindrical Shells

The effect of boundary conditions is very important in the analysis of cylindrical shells, and is rarely studied in the literature due to its difficult experimental simulation. For large structures such as shell roofs, the type of boundary supports is among the major factors that can minimize the stresses and deflections. In this study, experimental and numerical investigations of the effect of different boundary supports for stiffened and un-stiffened cylindrical shells were conducted. Two different models of the stiffened and un-stiffened cylindrical shells with different boundary conditions, “pinned and with rigid diaphragms”, were studied. It was shown that by using rigid diaphragms for cylindrical shells, the deflections are minimized by 80%, and by (45–50) % for the stiffened cylindrical shells. From the experimental investigations and the numerical results obtained, the efficiency of the proposed boundary support types for cylindrical shells is confirmed, which can result in economic benefits

Diversification and Intensification in Parallel {SAT} Solving

International audienceIn this paper, we explore the two well-known principles of diversification and intensification in portfolio-based parallel SAT solving. These dual concepts play an important role in several search algorithms including local search, and appear to be a key point in modern parallel SAT solvers. To study their trade-off, we define two roles for the computational units. Some of them classified as Masters perform an original search strategy, ensuring diversification. The remaining units, classified as Slaves are there to intensify their master's strategy. Several important questions have to be answered. The first one is what information should be given to a slave in order to intensify a given search effort? The second one is, how often, a subordinated unit has to receive such information? Finally, the question of finding the number of subordinated units along their connections with the search efforts has to be answered. Our results lead to an original intensification strategy which outperforms the best parallel SAT solver, and solves some open SAT instances

EFFET DU REVÊTEMENT ET DES PARAMÈTRES DE COUPE SUR LA RUGOSITÉ DE SURFACE EN TOURNAGE À SEC DE L'ACIER 42CrMo4.

Dans ce document, une étude expérimentale est réalisée afin d'évaluer l'effet des paramètres de coupeet le matériau de revêtement sur les performances des outils de coupe en tournage de l'acier 42Cr Mo4. Une étude comparative a été réalisée entre deux outils en carbure non revêtu et revêtu avec une couche de revêtement Al2O3/TiCN,Lesoutils de coupe ayant la même géométrie. Dans cette étude nous avons utilise la  méthodologie de surface de réponse  applique  à un plans  d'expérience de taguchi (09 essais ), dont les paramètres  d'entrée  sont : la vitesse de coupe, la profondeur de passe et l'avance par tour. Le procédé ANOVA a été utilisée pour quantifier les effets des paramètres de coupe sur l'usinage des surfaces.L'effet des couches de revêtement sur la qualité de surface est également étudié. les résultats  montrent  que  l'avance  a une grande influence sur la rugosité  de surface (Ra) et on observe qu'une plus faible rugosité de surface est obtenue lors de l'utilisation de  (Al2O3/TiCN) plaquette revêtue.Mots Clés:Outil De Coupe, Revêtements Durs, RSM, Rugosité de surface, Caractérisation de Revêtement

Genetic ProgrammingTowards Automated Strategies in Satisfiability Modulo Theory

SMT solvers include many heuristic components in order to ease the theorem proving process for different logics and problems. Handling these heuristics is a non-trivial task requiring specific knowledge of many theories that even a SMT solver developer may be unaware of. This is the first barrier to break in order to allow end-users to control heuristics aspects of any SMT solver and to successfully build a strategy for their own purposes. We present a first attempt for generating an automatic selection of heuristics in order to improve SMT solver efficiency and to allow end-users to take better advantage of solvers when unknown problems are faced. Evidence of improvement is shown and the basis for future works with evolutionary and/or learning-based algorithms are raised

The WISDOM Radar: Unveiling the Subsurface Beneath the ExoMars Rover and Identifying the Best Locations for Drilling

The search for evidence of past or present life on Mars is the principal objective of the 2020 ESA-Roscosmos ExoMars Rover mission. If such evidence is to be found anywhere, it will most likely be in the subsurface, where organic molecules are shielded from the destructive effects of ionizing radiation and atmospheric oxidants. For this reason, the ExoMars Rover mission has been optimized to investigate the subsurface to identify, understand, and sample those locations where conditions for the preservation of evidence of past life are most likely to be found. The Water Ice Subsurface Deposit Observation on Mars (WISDOM) ground-penetrating radar has been designed to provide information about the nature of the shallow subsurface over depth ranging from 3 to 10 m (with a vertical resolution of up to 3 cm), depending on the dielectric properties of the regolith. This depth range is critical to understanding the geologic evolution stratigraphy and distribution and state of subsurface H2O, which provide important clues in the search for life and the identification of optimal drilling sites for investigation and sampling by the Rover's 2-m drill. WISDOM will help ensure the safety and success of drilling operations by identification of potential hazards that might interfere with retrieval of subsurface samples

A Four-Year Multi-Center Retrospective Observational Study of Pediatric Emergency Medical Services Utilization in a Large Metropolitan Health System

Study Objectives: The COVID-19 pandemic has significantly decreased pediatric emergency department (ED) utilization. The objective of this study was to quantify the characteristics of pediatric EMS utilization both before and during the COVID-19 pandemic in a metropolitan health care system. Methods: We performed a multi-center, retrospective observational study of all pediatric ED visits between 1/1/2018 and 12/31/2021, that presented to one of nine EDs within our health system. The data were sorted by mode of arrival; children arriving to the ED via EMS, or arrival by other means. Data collection included a variety of demographic and clinical variables. We compared overall pediatric ED patients’ arrival methods as well as ED and EMS volumes by year using a binomial test with a null hypothesis that the population proportion equals 50%. Analysis compared ED mode of arrival, admission rate, and Emergency Severity Index (ESI) triage scores using chi-square tests. Results: There were 201,313 pediatric ED encounters for 118,744 unique patients meeting the inclusion criteria. There were 8,815 (4.38%) children who arrived via EMS compared to 192,498 (95.62%) children who arrived by other means (p \u3c 0.0001). Children who arrived via EMS had a higher admission rate of 22.27% (1963) compared to 5.9% (11,351, p \u3c 0.0001). ESI among children arriving via EMS was higher, with 44.3% (3847) having ESI 1 or 2 triage scores compared to 8.8% (16,790) for children arriving by other means (p \u3c 0.0001). Overall pediatric ED mortality was 0.03% (61 deaths), with 86.9% (53) of those children arriving via EMS (p \u3c 0.0001). Pediatric ED and EMS volumes in 2018 and 2019 pre-pandemic were 127,652 ED visits and 5,306 EMS visits, respectively, compared to 73,661 and 3,509 visits in 2020 and 2021. This represents a 42.3% overall reduction in pediatric ED visits (p \u3c 0.0001) and a 33.9% reduction in pediatric EMS visits (p \u3c 0.0001). Conclusion: Approximately 5% of pediatric ED encounters in our health system arrived via EMS. These children appeared to have higher acuity presentations and required inpatient services more often than children who arrived by other means. Pediatric ED and EMS encounters have decreased substantially since the onset of the pandemic

Pareto Autonomous Local Search

This paper presents a study for the dynamic selection of operators in a local search process. The main purpose is to propose a generic autonomous local search method which manages operator selection from a set of available operators, built on neighborhood relations and neighbor selection functions, using the concept of Pareto dominance with respect to quality and diversity. The latter is measured using two different metrics. This control method is implemented using the Comet language in order to be easily introduced in various constraint local search algorithms. Focusing on permutation-based problems, experimental results are provided for the QAP and ATSP to assess the method’s effectiveness

Compatibility between Calpurnia aurea leaf extract, attraction aggregation, and attachment pheromone and entomopathogenic fungus Metarhizium anisopliae on viability, growth, and virulence of the pathogen

Metarhizium anisopliae sensu stricto (ss) (Metsch.) Sorok. isolate ICIPE 07 is being developed as biopesticide for the control of ticks. In addition, leaf extracts of Calpurnia aurea Benth, and the attraction aggregation and attachment pheromone (AAAP) are being used as ticks’ attractant. The three agents are being considered for use in combination in an autodissemination approach, whereby ticks that are attracted to semiochemicals are infected with the inoculum. Experiments were therefore conducted to evaluate in vitro the compatibility between C. aurea, AAAP, and the M. anisopliae on vegetative growth, conidial production, and spore viability. Calpurnia aurea leaf extract was compatible with the fungus at all the concentrations tested, whereas AAAP inhibited all the fungal growth parameters. The virulence of M. anisopliae formulated in emulsifiable extracts of C. aurea was also tested against different developmental stages of Rhipicephalus appendiculatus in laboratory bioassays. No significant differences in virulence were observed between M. anisopliae applied alone and M. anisopliae formulated in different concentrations of C. aurea leaf extracts. These results suggest that C. aurea leaf extracts is compatible with M. anisopliae and could be mixed together for “spot-spray” treatments as low-cost and environmental-friendly technology to control ticks in grazing field, while AAAP should be used separately.Bioscience Eastern and Central Africa Network (BecANet) and the Canadian International Development Agency (CIDA).http://link.springer.com/journal/10340hb2013mn201

A new flat shell finite element for the linear analysis of thin shell structures

In this paper, a new rectangular flat shell element denoted ‘ACM_RSBE5’ is presented. The new element is obtained by superposition of the new strain-based membrane element ‘RSBE5’ and the well-known plate bending element ‘ACM’. The element can be used for the analysis of any type of thin shell structures, even if the geometry is irregular. Comparison with other types of shell elements is performed using a series of standard test problems. A correlation study with an experimentally tested aluminium shell is also conducted. The new shell element proved to have a fast rate of convergence and to provide accurate results