Multiparametric robust solutions for combinatorial problems with parameterized locally budgeted uncertainty

In this paper we studied combinatorial problems with parameterized locally budgeted uncertainty. We are looking for a solutions set such that for any parameters vector there exists a solution in the set with robustness near optimal. The algorithm consists of applying a multiparametric algorithm to obtain a near optimal multiparametric solution relative to the objective function for a combinatorial problem defined to find a robust solution for parameters fixed. As far as we know this is the first algorithm presented to do that task. Computational experience is presented to shortest path and $p$-medians problemsComment: 26 pages including 7 tables and 4 appendice

Explicit sets with ideal robustness are achievable in combinatorial optimization problems with cost uncertainty

We present an standard constraints generation algorithm to find an explicit set whose robustness is equal to the robustness of the feasible solution set of a combinatorial optimization problem with cost uncertainty. Computational experience shows that for problems with moderate dimensions the running time of the algorithm may be tolerable and in many cases the number of solutions required to achieve near-ideal robustness may be manageable for decision makers.Comment: 11 pages, 3 tables, 2 figure

Inference from large sets of radiocarbon dates: Software and methods

ABSTRACTThe last decade has seen the development of a range of new statistical and computational techniques for analysing large collections of radiocarbon (14C) dates, often but not exclusively to make inferences about human population change in the past. Here we introduce rcarbon, an open-source software package for the R statistical computing language which implements many of these techniques and looks to foster transparent future study of their strengths and weaknesses. In this paper, we review the key assumptions, limitations and potentials behind statistical analyses of summed probability distribution of 14C dates, including Monte-Carlo simulation-based tests, permutation tests, and spatial analyses. Supplementary material provides a fully reproducible analysis with further details not covered in the main paper.ER

The cultural evolution of adaptive-trait diversity when resources are uncertain and finite

In this paper, we seek to build on existing mathematical studies of cultural change by exploring how the diversity of adaptive cultural traits evolves by innovation and cultural transmission when the payoff from adopting traits is both uncertain and frequency dependent. The model is particularly aimed at understanding the evolution of subsistence trait diversity, since the payoff from exploiting particular resources is often variable and subject to diminishing returns as a result of overexploitation. We find that traits that exploit the same shared resource evolve most quickly when intermediate rates of cultural transmission promote fluctuation in trait diversity. Higher rates of cultural transmission, which promote predominantly low diversity, and lower rates, which promote predominantly high diversity, both retard the adoption of traits offering higher payoff. We also find that the distribution of traits that exploit independent resources can evolve towards the theoretical Ideal Free Distribution so long as the rate of cultural transmission is low. Increasing the rate of cultural transmission reduces trait diversity, so that a more limited number of "niches" are occupied at any given time

Design of a New Medium-temperature Stirling Engine for Distributed Cogeneration Applications☆

Abstract This paper presents and discusses the design and first prototype realization for a brand new generation of Stirling engines. This unit is realized within the DiGeSPo Project, in which it is coupled with a small-size parabolic trough concentration solar field. The engine is conceived for working with low-temperature heat sources (200-300 C), in order to match the typical temperatures for the solar field itself. The first part presents the thermodynamic design, which is realized by using models and simulations, and give the specifications for each component, including pistons dimensions; the number, length, diameter for the heat exchangers tubes; regenerators porosity, length and diameter. Four independent and equally working spaces were chosen, as a compromise between the compactness of the overall system, limits imposed by the maximum charging pressure, and the target electrical power (3 kW). The parameters of the overall system were optimized during this phase with an iterative procedure, taking into account different concurrent constraints, such as the heat exchange requirements, mechanical friction power losses, and small dead spaces. The engine has been subsequently arranged in a double-acting mechanical configuration, in which the cylinders are opposed as in a boxer engine. This configuration gives the advantages of reducing leaking losses and can work with four pistons. The heat exchangers, which are the most crucial and complex components, have been realized by the Selective Laser Melting (SLM) manufacturing technique. The specific scientific and technical details related to a low-temperature Stirling engine, and the solutions adopted, are discussed and presented trough the paper, and finals recommendations are provided

Risk factors for the occurrence of sexual misconduct during archaeological and anthropological fieldwork

AbstractFieldwork is crucial to advancing knowledge in archaeology and anthropology, but previous works suggests that between 64 and 68 percent of respondents experience sexual misconduct during fieldwork. Going forward, fieldwork must be made safe and inclusive. To achieve this, we must understand why sexual misconduct takes place during fieldwork. We surveyed an international sample of archaeologists and anthropologists (n=300) about their most recent fieldwork experience. We examine evidence for risk factors predicting sexual misconduct in fieldsites, and our findings suggest that length of fieldwork, presence and communication of policies and protocols, and the gender and sexuality of the individual are all significant. In particular, we find evidence for increased risk to nonmale and nonheterosexual individuals. We also gathered qualitative evidence from our respondents, who reported that in some cases they were discouraged from reporting and faced retaliation, they were dissatisfied with the handling of complaints, and fieldsite policies and protocols were not consistently or effectively implemented. Fieldwork can be a high‐risk environment for marginalized individuals to experience sexual misconduct, and when clear policies and procedures are lacking, it can also be a low‐risk environment for perpetrators in terms of consequences. To make fieldwork a safe environment for all, policies and protocols that mitigate the risk of sexual misconduct must be consistently implemented and properly communicated.</jats:p

Modifiable reporting unit problems and time series of long-term human activity.

This paper responds to a resurgence of interest in constructing long-term time proxies of human activity, especially but not limited to models of population change over the Pleistocene and/or Holocene. While very much agreeing with the need for this increased attention, we emphasize three important issues that can all be thought of as modifiable reporting unit problems: the impact of (i) archaeological periodization, (ii) uneven event durations and (iii) geographical nucleation-dispersal phenomena. Drawing inspiration from real-world examples from prehistoric Britain, Greece and Japan, we explore their consequences and possible mitigation via a reproducible set of tactical simulations. This article is part of the theme issue 'Cross-disciplinary approaches to prehistoric demography'.ERC Stg Grant (ENCOUNTER Project - 801953

Novel system for distributed energy generation from a small scale concentrated solar power

The present work describes the realization of a modular 1-3 kWe, 3-9 kWth micro Combined Heat and Power (m-CHP) system based on innovative Concentrated Solar Power (CSP) and Stirling engine technology. The cogeneration of energy at distributed level is one of leading argument in large part of energy policies related to renewable energy resources and systems. This CSP m-CHP will provide electrical power, heating and cooling for single and multiple domestic dwellings and other small buildings. The developed system integrates small-scale concentrator optics with moving and tracking components, solar absorbers in the form of evacuated tube collectors, a heat transfer fluid, a Stirling engine with generator, and heating and/or cooling systems; it incorporates them into buildings in an architecturally acceptable manner, with low visual impact. Some good results have already been achieved, while developments on several technology subcomponents will be finalized through first part of 2013. Two Cer.Met. have been modelled, realized and tested. The up scaled receiver, in form of Cer.Met. coating based on TiO2 - Nb, has been confirmed an absorptance of 0.94 and emittance of 0.1 (@350°C). A second Cer.Met. coating based on SiO2 - W has demonstrated an absorptance of 0.93 and emittance of 0.09 (@350°C). A full-evacuated solar tube has been designed and realized, with absorber of 12 mm in diameter and length in 2 meters. The system is provided of a concentration ratio 12:1, and a single module is 200 cm long, 40 cm wide and 20-25 cm high. Two or more modules can be combined. The evacuated solar tube, located on the focus, has the selective absorber on a tube of 12 mm in diameter. A very thin glass mirror has been developed (< 1 mm). The overall mirror reflectivity has been measured, the verified value is 0,954. Research has proposed a high energy density, double acting Stirling engine, provided of innovative heat exchangers realized through Selective Laser Melting process. The engine is a low speed (250 RPM), high pressure (130 Bars) and compact solution able to be run at 300°C and generate 3,5 kW nominal power. The solar technology has actually entered the proof-of-concept stage. A solar plant has been installed in Malta, by Arrow Pharm company, supplying the industrial process of generated steam at 180°C and 3.5 absolute pressure. The solar collector's efficiency is close to 47% in presence of 900 W/m2 of direct solar radiation. During 2013, solar evacuated tubes with innovative Cer.Met. coating, together with new thin glass mirrors will upgrade the demonstration site, together with a new and innovative low temperature difference and high energy density Stirling. By end-2013, the system will be demonstrated, with the overall objective to achieve a minimum of 65% in solar collectors' efficiency at 300°C, and 12 - 15% of overall electrical efficiency by the Stirling cycle.peer-reviewe