Experimental and modeling study of the autoignition of 1-hexene/iso-octane mixtures at low temperatures

Autoignition delay times have been measured in a rapid compression machine at Lille at temperatures after compression from 630 to 840 K, pressures from 8 to 14 bar, \Phi = 1 and for a iso octane/1 hexene mixture containing 82% iso-octane and 18% 1 hexene. Results have shown that this mixture is strongly more reactive than pure iso-octane, but less reactive than pure 1 hexene. It exhibits a classical low temperature behaviour, with the appearance of cool flame and a negative temperature coefficient region. The composition of the reactive mixture obtained after the cool flame has also been determined. A detailed kinetic model has been obtained by using the system EXGAS, developed in Nancy for the automatic generation of kinetic mechanisms, and an acceptable agreement with the experimental results has been obtained both for autoignition delay times and for the distribution of products. A flow rate analysis reveals that the crossed reactions between species coming from both reactants (like H-abstractions or combinations) are negligible in the main flow consumption of the studied hydrocarbons. The ways of formation of the main primary products observed and the most sensitive rate constants have been identified

The Credit Channel of Monetary Policy and Housing Markets: International Empirical Evidence

This paper tests for the presence of a credit channel (particularly a bank-lending sub-channel) for monetary policy in the housing market. We argue that the importance of this channel for investment in residential housing is highly dependent on the structural features, and particularly the efficiency and institutional organization, of housing finance. We employ a VAR methodology to analyse this issue with respect to the housing markets of four European countries (Finland, Germany, Norway and the United Kingdom), which differ greatly in terms of structural features. Our results are generally consistent with the existence of a broad credit channel, whereas the bank-lending channel seems to be operational only under certain conditions. More importantly, our results are consistent with previous analyses of housing market efficiency, which strongly suggests the existence of a clear relationship between the presence of a credit (bank lending) channel, the efficiency level of housing finance, and the type of institutions that are active in mortgage provision.monetary transmission; bank lending channel; house prices; vector autoregressions

The Structure of Multiple Credit Relationships: Evidence from US Firms

When firms borrow from multiple concentrated creditors such as banks they appear to differentiate their allocation of borrowing. In this paper, we put forward hypotheses for this borrowing pattern based on incomplete contract theories and test them using a sample of small U.S. firms. We find that firms with more valuable, more redeployable, and more homogeneous assets differentiate borrowing more sharply across their concentrated creditors. We also find that borrowing differentiation is inversely related to restructuring costs and positively related to firms’ informational transparency. This evidence supports the predictions of incomplete contract theories: the structure of credit relationships appears to be used as a device to discipline creditors and entrepreneurs, especially during corporate reorganizations.Credit Relationships, Multiple Creditors, Borrowing Allocation

Liquidity Cycles

We study an economy where firms face credit constraints tied to the value of their assets and financiers differ in their information on the market for firms' assets. Financiers with poor information on the asset market make mistakes in asset liquidation, hoarding assets during booms and trading them during recessions. We find that asset liquidity and the composition -informed versus uninformed- of firms' financiers breed each other in a cumulative fashion and that their interaction generates cycles in asset values and outputAsset Liquidity, Business Fluctuations, Firm Financing

Ownership structure, governance, and innovation: Evidence from Italy

-Ownership, Agency problems, Technological change

Microplastics in the marine environment: new frontiers of investigation of their presence and related associated effects

The overall aim of this PhD thesis is to improve the investigation of the microplastics (MPs) presence in marine ecosystems and pursue understanding their impacts on marine species. To achieve these aims the main themes discussed in this PhD thesis were divided according to two main lines of research and a Citizen Science project. The first line of research is focused on the monitoring and assessment of the level of microplastic pollution in the marine environment (Mediterranean Sea) focusing on surface water, subsurface water, and sediments. This topic was pursued evaluating the limits of the standard methodologies used in the monitoring framework, designing upgrades in traditional sampling strategies and testing innovative sampling tools to collect more and more ecologically relevant data. Particular attention was paid to the study of the subsurface layers of the water column (approx. 10 m). With the aim to produce innovative knowledges and more data to better understand MPs dynamics and behavior, sampling strategy to collect samples from depth water was improved. In addition, the results obtained has allowed to compare depth with the surface to better describe the accumulation pattern of the MPs in the marine environment. Not only the sampling strategies were improved, but the laboratory procedurals analysis was implemented too. Even nowadays the laboratorial protocols employed in samples proceeding are globally widespread. The presence of globally shared standardized protocol is still missing. In fact, the personalized protocol that exists nowadays for the MPs detection analysis, producing an extremely variability in data from all over the world, makes it difficult to compare to each other. In the current thesis the procedural strategy adopted, was focused on enhancing the MPs extraction from the samples either from surface water, subsurface layer of the water column and sediments, with the aim to achieve the better strategy to propose a universal protocol of extraction. The achievement of the presented aims regarding sampling strategy and procedural analysis were pursued thanks to three sampling campaigns performed in the Mediterranean Sea, described in the first chapter that offers the possibility to test the designed upgrades. In addition, results obtained from the three sampling campaigns were used as point of comparison to confirm the actual efficiency of the adopted upgrades. Data obtained highlight that MPs and microfiber (MFs) distribution in the marine environment was not uniform, conversely it is subjected to a patchy distribution pattern. An accumulation of plastic is observed in sediments too, especially for those plastic particles composed in high density polymers (i.e. PET and PVC) and fibers. The second line of research is aimed to test the ecotoxicological effect of natural weathered plastic leachates on a battery of marine model organisms. To achieve this goal, a battery of traditional and innovative marine model organisms was adopted, and innovative endpoints were investigated. Leachates are a long-lasting threat of our era, caused by the long-term permanence of plastic in the environment and their consequently degradation. However, the investigation in the effects caused by plastic leachates is still poorly understood. Most of the studies in this context were focused on MPs leachates obtained by artificial aged plastic, avoiding the effect of exposure to the natural environment. Conversely, in the ecotoxicological study proposed in this thesis the toxicity of environmental aged plastics collected in different areas of the European marine compartment was investigated. Plastic collected in the field were secondly micronized in order to propose a more realistic scenario. Then MPs obtained have been leached and tested at different concentration. The ecotoxicological investigations pursued in this context were aimed to better define the ecological risk to which marine organisms are exposed and to define the possible response that organisms can produce as effect of the interaction with MPs. In addition, a Weight of Evidence (WOE) model was performed in collaboration with the Polytechnical University of Marche (UNIVPM), with the aim of better define the environmental hazard of the tested leachates. Our findings pointed out that plastic weathered in natural conditions are able to release leachates solutions that affect the behavioural end-point of different marine organisms with a degree of environmental hazard between absent and slight. Finally, the third chapter of this thesis is dedicated to a Citizen Science project aimed to test an innovative sampling strategy to monitor MPs accumulation in nearshore. While many studies have investigated beached and floating microplastics (size < 5 mm) in surface waters offshore, there is almost no information on floating microplastics in surface waters at less than a few hundred meters from the coastline, where the largest plastic mass flux is suspected to occur. Due to the extreme proximity to coastal sources of pollution: tourism activities, riverine mouth systems, wastewater treatment plants and high populated cities centers coupled with the high morphological variability of the coast, the near coast environment is interested in predicted accumulation of marine debris. At the same time the coastal line is not approachable with the boats usually used by the researchers for the monitoring of MPs in open sea, caused by legislative restrictions and practical difficulties. With this purpose the citizen science project here shown was aimed to test an innovative sampling strategy to monitor MPs pollution in nearshore by using a less impactful sampling method. This project in fact, proposes to the citizens involved to participate in the collection of nearshore surface water samples by using the innovative Minimanta net, a smaller and lightweight version inspired to the traditional one. This reduced device allows to tow it from floating gears like kayaks, that are less impacting and more agile to manage in nearshore environment. Coupled with this aim the second objective of the project was to increase the awareness and the responsibility of the participants in plastic pollution theme, to promote a sustainable way of life

The Role of Inverter-based Generation in Future Energy Systems: An Oriented Decentralized Strategy for Reactive Power Sharing in Islanded AC Microgrids and a Techno-Economic Approach to Inertia Requirements Assessment of the Italian Transmission Network

One of the most impacting changes in the electricity energy scenario of the latest decades is the extensive increase of Distributed Energy Resources (DER) including Electrical Storage Systems (EES), fuel cells and Renewable Energy Sources (RES), such as Photovoltaic (PV) and Wind Turbines (WT). The integration of a rapidly increasing share of inverter-based generation poses relevant challenges in terms of frequency and voltage control both in Islanded Microgrids (MG) and traditional transmission networks. For the sake of complementarity, the thesis focuses on reactive power and voltage regulation in MG and frequency instability problems in a future Italian transmission network. In MG with converter-based energy production, one of the main problems is the proper reactive power sharing among DER and related voltage regulation. In this concern the most used approach is based on the conventional droop control; however, it presents some relevant drawbacks. In SECTION A an Advanced Droop Control strategy (ADC) and an Advanced Boost Control strategy (ABC) are proposed, to approach primary voltage control and reactive power sharing among Grid-Supporting inverters in islanded MG. The strategies are presented defining their control laws and the control schemes together with the relevant stability analysis. Then, an analytical procedure is developed for each control methods to set proper control parameters. Next, a comparison between the new strategies and droop conventional control is performed with simulations on a common benchmark MG, in order to show that new strategies, according to their specific control logics, are able to guarantee improved performance in terms of the combined regulation of voltage and reactive power. Considering the traditional electric system, one of the main consequences of the increasing penetration of RES is, besides of the decrease of the system short-circuit power, the reduction of the electric system inertia: this could lead to frequency instability problems in case of severe perturbations, especially for what concerns the Rate of Change of Frequency (RoCoF)and the frequency nadir. In SECTION B, the thesis provides a technical-economic methodology for the estimation of the amount of additional inertia that will be needed in the Italian Transmission Network in a prospective 2030 scenario, in order to limit the RoCoF within sustainable values. Moreover, the algorithm optimally commits synthetic inertia contribution from RES and Battery Energy Storage Systems (BESS) and installation of Synchronous Compensators (SC) among the Italian market areas. The method is designed to be sufficiently simple to process a relevant number of working scenarios in order to exploit the relevant quantity of information owned by the TSO. Results have shown to be highly accurate as outline by comparison with detailed time domain simulations

Women\u27s educational pursuits: Effects on marital and relationship happiness

This study uses a descriptive design to investigate how attending college may change a woman\u27s perception of her happiness with her marriage or primary relationship. Also assessed is the presence of value change since entering college, and how such changes may affect the woman\u27s perception of her marriage or relationship. Marital happiness was assessed in nine relationship domains by using a likert scale. The domains that showed a statistically significant decrease in marital/relationship happiness were: household responsibilities, social activities, money, and sex. The independence domain was the only one that showed a statistically significant increase in marital happiness. Ninety percent of the participants reported their values have changed since their return to school. Seventy-five percent of the participants reported that value changes did affect their marriage or relationship