Collective Bargaining under Complete Information

In this paper, we build and structurally estimate a complete information bargaining model of collective negotiation for Spain. For large firms, the assumption of complete information seems a sensible one, and it matches the collective bargaining environment better than the one provided by private information models. The specification of the model with players having different discount factors allows us to measure their relative bargaining power, a recurrent question in the theory of bargaining. We find that both entrepreneurs and workers have high discount factors, and no evidence that entrepreneurs have bigger bargaining power as usually assumed.Delays, sequential bargaining, structural estimation

Modeling Urban Freight Generation: A Study of Commercial Establishments’ Freight Needs

Increasing urbanization, and the environmental and liveability impacts associated with urban activity, have directed attention to the need for sustainable cities. Achieving sustainable urban development requires including freight systems in strategic urban development plans. In this context, joint efforts involving academia and public- and private sector to collect the right data and develop suitable models, can contribute toward a better understanding of establishments’ freight needs, the quantification of freight’s traffic impacts and the development of appropriate methods to support decision making and strategic plans. This paper studies urban commercial establishments’ freight needs and impacts on traffic using data collected from establishments in the City of Gothenburg (Sweden). The data cover different zones of the city and include commercial sectors found typically in urban cores (e.g., retailers, food services, health care, public sector offices and education). The paper introduces a set of statistical models—developed based on regression analyses and discrete choice models—to estimate the number of freight trips produced and attracted per week, and the attraction of weight and volumes of freight. In addition to shed light on the factors determining establishments’ freight- and freight trips generation, the models are designed with the purpose of assisting planning and policy design efforts, thus the explanatory variables are selected based on suitability and availability. The results show that retailers of perishable goods have the highest freight trip generation per establishment, followed by public sector offices and education establishments, retailers of non-perishable goods and restaurants. The results also reveal a heterogeneity between sectors, and a differential business size effect across commercial sectors

Caractérisation et évaluation des fibres de grains d'Asclépias Syriaca pour le développement d'isolants thermiques durables et le renforcement de matrices thermodurcissables

Abstract: The seed fibers or comas of Asclepias Syriaca, also known as milkweed floss, distinguish themselves from other natural fibers due to their gloss, softness, and hollow structure. Their abundance and unique microstructure suggest that these fibers could serve as sustainable and lightweight materials for various applications, including clothing, construction, thermal insulation, polymer reinforcement, water treatment, and oil absorption. With these potential applications in mind, this research study aimed to characterize and understand the properties of milkweed floss, as well as explore its prospective uses as a sustainable material for developing thermo-acoustic insulation systems and lightweight reinforced thermosetting matrices. To fully understand the advantages and potential applications of milkweed floss in insulation and polymer reinforcement, the first part of the project was focused on evaluating the microstructure, thermo-acoustic insulating properties, and mechanical and thermal resistances of the fibers. Additionally, a portion of the fibers was treated with acetone, and their properties were measured to analyze the effect of this treatment. Milkweed floss exhibited an average elastic modulus of 3.0 GPa, a thermal resistance comparable to that of other natural fibers, and superior thermo-acoustic insulation capacity than a traditional insulator such as expanded polystyrene. It was observed that the acetone treatment had no impact on the microstructure or acoustic insulation capacity of the fibers. The acetone treatment improved the thermal resistance and thermal conductivity of the fibers but decreased their elastic modulus. The second part of the project comprised the study of the combined effect of temperature, relative humidity, and fiber content on the specific heat capacity of milkweed floss, as well as the thermal conductivity and thermal diffusivity of nonwoven mats made of milkweed floss. The specific heat capacity of milkweed and thermal conductivity of the nonwovens increased with temperature. The thermal conductivity and thermal diffusivity of the nonwovens displayed significant variations only at relative humidity levels above 30%. Additionally, the thermal diffusivity and thermal conductivity decreased as the fiber content in the nonwovens increased. The optimal balance between good insulation properties and fiber consumption was achieved using nonwoven mats with a fiber content ranging from 20 to 25 kg/m3. In the third and final section of the project, native and acetone-treated milkweed floss were used to produce milkweed floss-reinforced epoxy composites. The microstructure, thermal conductivity, and thermos-mechanical behavior of the composites were analyzed to assess the reinforcing effect of milkweed floss. It was found that the composites reinforced with native or acetone-treated milkweed floss were 7.4% and 10.3% lighter than the epoxy resin alone, respectively. The specific elastic modulus of the resin increased by 9.6% and 20.1% with the addition of native or acetone-treated fibers, respectively. The thermal conductivity of the epoxy decreased by 7.8% and 15.6% with the use of native and acetone-treated fibers, respectively. The results of this study demonstrated several technical advantages of using milkweed floss as a sustainable and lightweight option for thermal insulation and polymer reinforcement.Les fibres de graines ou comas d'Asclepias Syriaca, aussi connues sous le nom de soie d'asclépiade, se distinguent des autres fibres naturelles par leur douceur et leur structure creuse. Leur abondance et leur microstructure unique suggèrent que ces fibres pourraient être utilisées comme matériaux durables et légers pour diverses applications, notamment dans l'industrie textile, la construction, l'isolation thermique, le renforcement de polymères, le traitement de l'eau et l'absorption d'huile. Cette étude visait à caractériser et comprendre les propriétés des fibres d'asclépiade, ainsi qu'à explorer leurs utilisations potentielles en tant que matériau durable pour le développement de systèmes d'isolation thermo-acoustique et de renforcement léger pour des matrices thermodurcissables. Pour comprendre les avantages et les applications potentielles de la soie d'asclépiade dans l'isolation et le renforcement de polymères, la première partie de ce projet s'est concentrée sur l'évaluation de la microstructure, des propriétés d'isolation thermo-acoustique, ainsi que des résistances mécaniques et thermiques des fibres d’asclépias. Une partie des fibres a été traitée avec de l'acétone, et leurs propriétés ont été mesurées afin de comprendre l'effet de ce traitement. Les résultats de la première étude ont montré que la soie d'asclépiade présente un module d'élasticité moyen de 3,0 GPa, une résistance thermique comparable à celle d'autres fibres naturelles, et une capacité d'isolation thermo-acoustique supérieure à celle d'un isolant traditionnel tel que le polystyrène expansé. Il a été observé que le traitement à l'acétone n'avait aucun impact sur la microstructure ou la capacité d'isolation acoustique des fibres. Le traitement à l'acétone a amélioré la résistance thermique et la conductivité thermique des fibres, mais a diminué leur module d'élasticité. La deuxième partie du projet a porté sur l'étude de l'effet combiné de la température, de l'humidité relative et de la teneur en fibres sur la capacité calorifique spécifique de la soie d'asclépiade, ainsi que sur la conductivité thermique et la diffusivité thermique des mats non tissés composées de soie d'asclépiade. La capacité calorifique spécifique de la soie d'asclépiade et la conductivité thermique des mats non tissés augmentaient avec la température. La conductivité thermique et la diffusivité thermique des non tissés présentaient uniquement des variations significatives à des niveaux d'humidité relative supérieurs à 30 %. De plus, la diffusivité thermique et la conductivité thermique diminuaient avec l'augmentation de la teneur en fibres dans les non tissées. Un équilibre optimal entre de bonnes propriétés d'isolation et une consommation de fibres a été atteint en utilisant des mats non tissés avec une teneur en fibres comprise entre 20 et 25 kg/m3. Dans la troisième partie du projet, des fibres d'asclépiade naturelles et traitées à l'acétone ont été utilisées comme renfort pour des composites époxy. La microstructure, la conductivité thermique et le comportement thermomécanique des composites ont été analysés pour comprendre l'effet de renforcement de la soie d'asclépiade sur la résine époxy. Il a été observé que les composites renforcés par des fibres d'asclépiade naturelles ou traitées à l'acétone étaient respectivement 7,4 % et 10,3 % plus légers que la résine époxy seule. Le module élastique spécifique de la résine a augmenté de 9,6 % et 20,1 % avec l'ajout de fibres naturelles ou traitées à l'acétone, respectivement. La conductivité thermique de l'époxy a diminué de 7,8 % et 15,6 % avec l'utilisation de fibres naturelles et traitées à l'acétone, respectivement. Les résultats de cette étude ont démontré plusieurs avantages techniques de l'utilisation de la soie d'asclépiade comme une option durable et légère pour l'isolation thermique et le renforcement de polymères thermodurcissables

Assessing the magnitude of freight traffic generated by office deliveries

This paper studies the impact of offices on urban freight traffic. Research on freight activity generated by offices is very limited because they are not seen as important contributors to urban freight traffic, and because the amount of deliveries per office is very small compared to the number of deliveries per establishment in freight-intensive sectors (e.g., retail, wholesale, manufacturing). However, the number of offices in cities is so large that altogether they represent a significant share of urban deliveries and generate a nonnegligible share of urban freight traffic. Hence, the relevance of quantifying their freight trip generation. This paper uses the City of Stockholm as a case study. The author collected data from offices and other establishments, estimated regression models and applied them to the city. The results show that offices represent 36% of establishments in Stockholm, 62% of employees and are responsible for 15% of freight trips generated in the city

Numerical study of relaxation in electron glasses

We perform a numerical simulation of energy relaxation in three-dimensional electron glasses in the strongly localized regime at finite temperatures. We consider systems with no interactions, with long-range Coulomb interactions and with short-range interactions, obtaining a power law relaxation with an exponent of 0.15, which is independent of the parameters of the problem and of the type of interaction. At very long times, we always find an exponential regime whose characteristic time strongly depends on temperature, system size, interaction type and localization radius. We extrapolate the longest relaxation time to macroscopic sizes and, for interacting samples, obtain values much larger than the measuring time. We finally study the number of electrons participating in the relaxation processes of very low energy configurations.Comment: 6 eps figures. To be published in Phys. Rev.