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In the exploration of celestial bodies, including planets, moons, and asteroids, it is useful to identify stable orbits in which the orbital elements remain, on average, constant (referred to as frozen orbits). This paper aims to investigate the feasibility of frozen orbits for a small body, such as a probe, orbiting a main body under the perturbation due to the gravitational attraction of an inner third-body, on a circular (or slightly eccentric) orbit coplanar with the main body equator, by means of an approach based on mean element theory. The disturbing potential has been developed in Legendre polynomials up to order l = 5 (triakontadipole level of approximation). Thus, the double-averaged potential function and the associated constants of motion have been determined up to the same order. Then, by applying the Lagrange Planetary Equations, the secular and long-term orbital element variations have been obtained. Therefore, frozen orbital solutions have been evaluated, and the effects on them of the addition of main body oblateness perturbation have been considered. Furthermore, the procedure has been repeated, and the frozen solutions are re-evaluated in the case of a disturbing body with small eccentricity up to order l = 4 (hexadecapole level of approximation). These solutions offer significant advantages in exploring bodies subject to a notable perturbation from an inner third-body, such as binary asteroid systems. • Frozen orbits for the inner third-body problem. • Inner circular planar third-body: Double-averaged potential up to triakontadipole. • Inner slightly eccentric planar third-body up to hexadecapole. • Orbital solutions for binary asteroid observation. [ABSTRACT FROM AUTHOR]

The High Energy Modular Ensemble of Satellites (HERMES) project intends to build an all-sky monitor operating from keV to MeV for the detection and localisation of transient events, like gamma ray bursts. HERMES is a modular observatory composed by detectors on-board of nanosatellites. HERMES aims to revolutionise the world of multi-messenger astrophysics thanks to the innovative concept of a modular instrument based on small satellites and characterised by reduced design and development times and low costs, in the face of high technological content and scientific profile of the mission. A first part of the project, HERMES Technological Pathfinder, composed of three CubeSats, aims to demonstrate the feasibility of detecting transient phenomena in high energy with small satellites. The next phase of the project, HERMES Scientific Pathfinder, will expand the constellation up to six satellites, allowing routinely accurate triangulation measurements. This paper presents an analysis that aims to be propaedeutic for the design of the final HERMES Full Constellation, which will be an all-sky monitor made up of tens/hundreds of nanosatellites in Low Earth Orbit with a total effective area of ∼ m 2. An adequate number of nanosatellites, simultaneously detecting a transient, provides a source localisation accuracy of the order of magnitude of few arcmin and large effective area. The objective of this work is to define possible strategies of injection in orbit of the complete constellation. In this first analysis we used only the number of triangulable Gamma Ray Bursts (simultaneously detected by at least three nanosatellites) as discriminating factor in order to maximise the constellation performance. By achieving the goal of at least a mean number of 20 Gamma Ray Bursts triangulated per nanosatellite over the two years life-time, optimal configurations for the complete constellation, consisting of seven to fourteen CubeSats, have been identified. • High Energy Modular Ensemble of Satellites (HERMES) mission. • Propaedeutic analysis for the design of the final Full Constellation. • Nanosatellites constellation for fast detection and positioning of Gamma Ray Bursts. • All-sky coverage constellation based on small satellites in Low Earth Orbit. • Maximisation of Gamma Ray Bursts triangulable during the lifetime by each satellite. • Robustness analysis: atmospheric drag, solar radiation pressure and early failures. [ABSTRACT FROM AUTHOR]

Abstract Due to conservative design models and safe construction practices, infrastructure usually has unknown amounts of reserve capacity that exceed code requirements. Quantification of this reserve capacity has the potential to lead to better asset-management decisions by avoiding unnecessary replacement and by lowering maintenance expenses. However, such quantification is challenging due to systematic uncertainties that are present in typical structural models. Field measurements, collected during load tests, combined with good structural-identification methodologies may improve the accuracy of model predictions. In most structural-identification tasks, engineers usually select and place sensors based on experience and high signal-to-noise estimations. Since the success of structural identification depends on the measurement system, research into measurement system design has been carried out over several decades. Despite the multi-criteria nature of the problem, most researchers have focused only on the information gained by the measurement system. This study presents a framework to evaluate and rank possible measurement-system designs based on a tiered multi-criteria strategy. Performance criteria for the design of measurement systems include monitoring costs, information gain, ability to detect outliers and impact of loss of information in case of sensor failure. Through including conflicting criteria, such as cost of monitoring and information gain, the optimal measuring system becomes a Pareto-like choice that ultimately depends on asset-manager preference hierarchies. Several potential preference scenarios are generated and results are compared using a full-scale test study, the Exeter Bascule Bridge. The framework successfully supports an informed design of measurement systems by providing an extensive set of alternatives, including the best solution defined probabilistically and for specific conditions when other near-optimal solutions might be preferred. [ABSTRACT FROM AUTHOR]

To improve lunar landing performances in terms of mission costs, trajectory determination and visibility the use of a single probe located over an assistance orbit around the Moon has been taken into consideration. To this end, the properties of two quasi-circular orbits characterised by a stable behaviour of semi-major axis, eccentricity and inclination have been investigated. The analysis has demonstrated the possibility of using an assistance probe, located over one of these orbits, as a relay satellite between lander and Earth, even in the case of landings on the far side of the Moon. A comparison about the accuracy in retrieving the lander’s state with respect to the use of a probe located in the Lagrangian point L2 of the Earth-Moon system has also been carried out. [ABSTRACT FROM AUTHOR]

Following an approach based on ground track analysis, original and compact relationships which permit the construction of ground track patterns and the determination of satellite arrangements able to generate appropriate track distance and revisit frequency over a given area are presented. These equations are valid in the general case of elliptical orbit and can easily be implemented in computer codes devoted to the design of single and multi-plane satellite constellations. [ABSTRACT FROM AUTHOR]

This paper proposes a robustness analysis based on Multiple Criteria Decision Aiding (MCDA). The ensuing model was used to assess the implementation of green chemistry principles in the synthesis of silver nanoparticles. Its recommendations were also compared to an earlier developed model for the same purpose to investigate concordance between the models and potential decision support synergies. A three-phase procedure was adopted to achieve the research objectives. Firstly, an ordinal ranking of the evaluation criteria used to characterize the implementation of green chemistry principles was identified through relative ranking analysis. Secondly, a structured selection process for an MCDA classification method was conducted, which ensued in the identification of Stochastic Multi-Criteria Acceptability Analysis (SMAA). Lastly, the agreement of the classifications by the two MCDA models and the resulting synergistic role of decision recommendations were studied. This comparison showed that the results of the two models agree between 76% and 93% of the simulation set-ups and it confirmed that different MCDA models provide a more inclusive and transparent set of recommendations. This integrative research confirmed the beneficial complementary use of MCDA methods to aid responsible development of nanosynthesis, by accounting for multiple objectives and helping communication of complex information in a comprehensive and traceable format, suitable for stakeholders and/or decision-makers with diverse backgrounds. [ABSTRACT FROM AUTHOR]

Nanotechnology applications (nanoproducts) have entered the market or are expected to do so in the near future. Robust and science-based criteria are required to appraise and manage their sustainability. This paper describes the approach used to develop a comprehensive and reliable framework of criteria, which was missing until now, for evaluating the sustainability of nanoproducts. A literature review of the frameworks and tools employed to assess nanoproducts sustainability implications was firstly performed to select an initial set of criteria. A survey of experts in the sustainable nanotechnology domain was then conducted to elicit their knowledge in terms of completeness, reliability and validity of the criteria set. Ranking and correlation analyses completed the research by identifying the parameters of major interest as well as the links and dependencies between them. A total of 54 and 65 experts replied to the pilot and main survey, respectively. The reliability and validity of the criteria was assessed with the responses from both questionnaires, whereas the answers from the main survey were used to calculate the relative index of the criteria as well as their correlations. This research resulted in a framework composed of 68 criteria, which are structured into six main areas: (i) economic performance; (ii) environmental impacts, (iii) environmental risk assessment; (iv) human health risk assessment; (v) social implications and (vi) technical performance. This study helps to broaden the understanding on the identification of criteria for sustainability assessments. It also provides those interested in evaluating nanotechnology implications with the basis for real case studies, possibly by integrating available information with the stakeholders using tools that support decision-making. [ABSTRACT FROM AUTHOR]

Sustainability assessments require the management of a wide variety of information types, parameters and uncertainties. Multi criteria decision analysis (MCDA) has been regarded as a suitable set of methods to perform sustainability evaluations as a result of its flexibility and the possibility of facilitating the dialogue between stakeholders, analysts and scientists. However, it has been reported that researchers do not usually properly define the reasons for choosing a certain MCDA method instead of another. Familiarity and affinity with a certain approach seem to be the drivers for the choice of a certain procedure. This review paper presents the performance of five MCDA methods (i.e. MAUT, AHP, PROMETHEE, ELECTRE and DRSA) in respect to ten crucial criteria that sustainability assessments tools should satisfy, among which are a life cycle perspective, thresholds and uncertainty management, software support and ease of use. The review shows that MAUT and AHP are fairly simple to understand and have good software support, but they are cognitively demanding for the decision makers, and can only embrace a weak sustainability perspective as trade-offs are the norm. Mixed information and uncertainty can be managed by all the methods, while robust results can only be obtained with MAUT. ELECTRE, PROMETHEE and DRSA are non-compensatory approaches which consent to use a strong sustainability concept, accept a variety of thresholds, but suffer from rank reversal. DRSA is less demanding in terms of preference elicitation, is very easy to understand and provides a straightforward set of decision rules expressed in the form of elementary “if … then …” conditions. Dedicated software is available for all the approaches with a medium to wide range of results capability representation. DRSA emerges as the easiest method, followed by AHP, PROMETHEE and MAUT, while ELECTRE is regarded as fairly difficult. Overall, the analysis has shown that most of the requirements are satisfied by the MCDA methods (although to different extents) with the exclusion of management of mixed data types and adoption of life cycle perspective which are covered by all the considered approaches. [ABSTRACT FROM AUTHOR]

Statement of problem: Debonding is a common cause of failure encountered with fiber posts and usually occurs along the post space-dentin adhesive interface. The ideal thickness of the resin cement needed to improve retentive bond strength is unknown. Purpose: The purpose of this study was to evaluate the effect of 4 different post-space diameters and related resin cement film thicknesses on the bond strength between fiber posts and root dentin. Material and methods: Eighty human maxillary central incisors with similar root lengths were selected, sectioned at the cemento-enamel junction, and the roots were treated endodontically. The roots were divided into 4 groups (n=20), and the post spaces were prepared to a depth of 8 mm using 1 of 4 different drills with a different diameter: Torpan drill ISO 90 for the control group (D90); and Torpan Drill ISO 100 (D100), Torpan Drill ISO 120 (D120), or Enapost Drill ISO 140 (D140) for the 3 test groups. Quartz fiber posts (Endo Lightpost), 0.9 mm in apical diameter, were luted (Panavia 21) in each specimen after dentin bonding procedures. The specimens were then subjected to a pullout test using a universal testing machine at a crosshead speed of 1.0 mm/min, and the maximum force required to dislodge each post was recorded (N). Data were analyzed using 1-way ANOVA and Tukey multiple comparisons tests (a=.05). Results: The mean bond strength values (SD) in N for the experimental groups D100 (181.7 (55.3)) and D120 (210.7 (55.0)) were higher (P=.036 and <.001, respectively) than that obtained for the D90 control group (138.5 (49.2)). The lowest mean value was recorded for the D140 group (91.1 (36.0)). All experimental groups showed significantly different results, when compared to the control group. A multiple comparison between experimental groups showed significant differences (P<.001). Only the comparison between D100 versus D120 was not significant. Conclusions: Data suggest that the resin cement film thickness influences the pullout strengths of fiber-reinforced posts. For the selected quartz fiber-reinforced post and resin luting cement, the highest bond strength values were not obtained when the thinnest cement layer was tested (D90) but when oversized post spaces were used (D100-D120). However, when the cement film thickness was too great (D140), the dislocation resistance of fiber-reinforced posts was significantly decreased. (J Prosthet Dent 2007;98:193-198) [Copyright &y& Elsevier]

Abstract: This study evaluated the effect of three post surface treatments on quartz-fiber post (a) retention and (b) morphology. A control group was not treated. Different treatments were performed for the other posts: silanization; etching by hydrofluoric acid 9.5%; sandblasting with 50 μm Al2O3. Two specimens of each group were submitted to a qualitative scanning electron microscopy (SEM) analysis. Remaining specimens were luted in prepared root canals (n = 10) and retentions were determined using a universal testing machine. Retentive post bond strengths were significantly enhanced with any tested post surface pretreatment. The increase in retentive strength was more remarkable in sandblasted and etched posts. Significant changes of post surfaces were SEM observed after different conditioning treatments. [Copyright &y& Elsevier]

Composite Indicators (CIs, a.k.a. indices) are increasingly used as they can simplify interpretation of results by condensing the information of a plurality of underlying indicators in a single measure. This paper demonstrates that the strength of the correlations between the indicators is directly linked with their capacity to transfer information to the CI. A measure of information transfer from each indicator is proposed along with two weight-optimization methods, which allow the weights to be adjusted to achieve either a targeted or maximized information transfer. The tools presented in this paper are applied to a case study for resilience assessment of energy systems, demonstrating how they can support the tailored development of CIs. These findings enable analysts bridging the statistical properties of the index with the weighting preferences from the stakeholders. They can thus choose a weighting scheme and possibly modify the index while achieving a more consistent (by correlation) index. • Composite indicator development is enhanced with advanced statistical analysis. • Tools to assess the information transferred from indicators to the index are proposed. • Two weight-optimization methods allow adjusting information transfer to the index. • The approaches are applied to a real case study on resilience of electricity supply. [ABSTRACT FROM AUTHOR]

This study proposes a set of key decision-making features of the contaminated site remediation process to assist in selecting the most appropriate decision support method(s). Using a case study consistent with the requirements of the U.S. regulation for contaminated sites management, this article shows that suitable Multiple Criteria Decision Analysis methods can be selected based on a dynamic and evolving problem structuring. The selected methods belong to the family of PROMETHEE methods and can provide ranking recommendations of the considered alternatives using variable structures of the criteria, evaluation of the alternatives and exploitation of the preference model. It was found that in order to support a quick and up-to-date application of powerful decision support techniques in the process of remediation of contaminated sites, decision analysts and stakeholders should interact and co-develop the process. This research also displays how such interactions can guarantee a transparent and traceable decision recommendation so that stakeholders can better understand why some alternatives perform comprehensively better than others when a multitude of inputs is used in the decision-making process. • Decision-making features for remediation of contaminated sites are proposed. • Decision analysis is used to aid the process of contaminated sites management. • The proposed approach is consistent with the relevant U.S. regulation. • Decision analysts and stakeholders should co-develop remediation processes. • A case study for land remediation is used to dynamically rank target alternatives. [ABSTRACT FROM AUTHOR]

The JUpiter ICy moons Explorer mission of the European Space Agency, that will be launched in the year 2022, will study the geodesy and physical characteristics of Jupiter and its icy moons Europa, Callisto and Ganymede. The final phase of this mission, planned for the year 2032, is still under investigation and foresees phases in circular orbit around Ganymede. In this paper two types of science orbits around Ganymede, that optimize the observational performances and the probe life-time, are proposed. While the first type allows, at “zero cost”, the obtaining of repeated observations of a given point of the surface, the second type, with a limited cost, adds to the periodicity of observation, the condition of synchronism with the Sun. This synchronism permits both the achievement of a condition of permanent sunlight for the probe, thus leading to an extension of the mission duration, and a minimization of the variations of spectral signature due to the Sun's position. [ABSTRACT FROM AUTHOR]

• A structured approach for robustness assessment of rankings is proposed. • Resilience of electricity supply security is analyzed for 140 countries. • 12 resilience-related indicators are quantified using a structured methodology. • 38 combinations of normalization methods and aggregation functions are applied. • General ranking trends and different levels of compensation are identified. Indicator-based approaches are suitable to assess multi-dimensional problems. In order to compare a set of alternatives, one strategy is to normalize individual indicators to a common scale and aggregate them into a comprehensive score. This study proposes the Electricity Supply Resilience Index (ESRI), which is a measure of a nation's electricity supply resilience. Starting from an initial set of individual indicators derived through a structured selection process, the ESRI is calculated for 140 countries worldwide. To account for robustness of the resulting resilience index, 38 combinations of eight normalization methods and six aggregation functions were considered. Results show a clear country ranking trend, with robust top- and low-performing countries across all combinations. However, the ranking disparity becomes large for average performing countries, especially if their indicators show high variability. Furthermore, the differences of the rankings are quantified through the Rank Difference Measure (RDM), which identifies the categorical scales and the minimum aggregator as the most different ones. Finally, the effects of different compensation levels of the aggregation functions are discussed. The findings of the present study aim to provide recommendations for policymakers on how composite indexes results depend on assumptions and chosen approaches. [ABSTRACT FROM AUTHOR]