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Optimal Adaptations over Multi-Dimensional Adaptation Spaces with a Spice of Control Theory
No full text(Self-)Adaptive software systems monitor the status of their requirements and adapt when some of these requirements
are failing. The baseline for much of the research on adaptive software systems is the concept of a feedback loop mechanism that monitors the performance of a system relative to its requirements, determines root causes when there is failure, selects an adaptation, and carries it out. The degree of adaptivity of a software system critically depends on the space of possible adaptations supported (and implemented) by the system. The larger the space, the more adaptations a system is capable of. This thesis tackles the following questions: (a) How can we define multi-dimensional adaptation spaces that subsume proposals for requirements- and architecture-based adaptation spaces? (b) Given one of more failures, how can we select an optimal adaptation with respect to one or more objective functions? To answer the first question, we propose a design process for three-dimensional adaptation spaces, named the Three-Peaks Process, that iteratively elicits control and environmental parameters from requirements, architectures and behaviours for the system-to-be. For the second question, we propose three adaptation mechanisms. The first mechanism is founded on the assumption that only qualitative information is available about the impact of changes of the system's control parameters on its goals. The absence of quantitative information is mitigated by a new class of requirements, namely Adaptation Requirements, that impose constraints on the adaptation process itself and dictate policies about how conflicts among failing requirements must be handled.
The second mechanism assumes that there is quantitative information about the impact of changes of control parameters on the system’s goals and that the problem of finding an adaptation is formulated as a constrained multi-objective optimization problem. The mechanism measures the degree of failure of each requirement and selects an adaptation that minimizes it along with other objective functions, such as cost. Optimal solutions are derived exploiting OMT/SMT (Optimization Modulo Theories/Satisfiability Modulo Theories) solvers.
The third mechanism operates under the assumption that the environment changes dynamically over time and the chosen adaptation has to take into account such changes. Towards this direction, we apply Model Predictive Control, a well-developed theory with myriads of successful applications in Control Theory. In our work, we rely on state-of-the-art system identification techniques to derive the dynamic relationship between requirements and possible adaptations and then propose the use of a controller that exploits this relationship to optimize the satisfaction of requirements relative to a cost-function. This adaptation mechanism can guarantee a certain level of requirements satisfaction over time, by dynamically composing adaptation strategies when necessary. Finally, each piece of our work is evaluated through experimentation using variations of the Meeting-Scheduler exemplar
Safe and Efficient Communication Protocols for Platooning Control
No full textModern vehicles are becoming smarter and smarter thanks to the continuous development of new Advanced Driving Assistance Systems (ADAS). For example, some new commercial vehicles can detect pedestrians on the road and automatically come to a stop avoiding a collision. Some others can obtain information about traffic congestion through the cellular network and suggest the driver another route to save time. Nevertheless, drivers (and our society as well) are always striving for a safer, cleaner, and more efficient way of traveling and standard, non-cooperative ADAS might not be sufficient. For this reason the research community started to design a vehicular application called “platooning”. Platooning simultaneously tackles safety and traffic congestion problems by cooperatively coordinating vehicles in an autonomous way. Traffic flow is optimized by using an advanced Adaptive Cruise Control (ACC), called Cooperative Adaptive Cruise Control (CACC), which drastically reduces inter-vehicle gaps. By being autonomously coordinated, platooning vehicles implicitly implement automated emergency braking, a fundamental application for freeway safety. The idea is to form optimized road trains of vehicles where the first drives the train, while the others autonomously follow at a close distance, without requiring the driver to steer, accelerate, or brake. Platooning can have an enormous impact on future transportation systems by increasing traffic flow (and thus reducing congestion), increasing safety, reducing CO2 emissions, and reducing the stress of driving. This application is extremely challenging due to its inter-disciplinary nature. Indeed, it involves control theory, vehicle dynamics, communication, and traffic engineering. In this thesis we are mostly concerned with the communication aspects of this application, which is fundamental for making the vehicles cooperate, improving the efficiency of the application with respect to a pure sensor-based solution. Application requirements are very tight and, given that the envisioned communication technology will be IEEE 802.11-based, there are concerns on whether these requirements can really be met. The focus of the thesis is in this direction.
The first contribution is the design of PLEXE, an extension for the widely used vehicular simulation framework Veins that enables research studies on various platooning aspects, including design and evaluation of control algorithms, communication protocols, and applications. The tool is open source and free to download and use, and it realistically simulates both communication and vehicle dynamics. This makes PLEXE a valid testing platform before real world deployment. The second contribution is a set of undirected information broadcasting (beaconing) protocols that specifically take into account the requirements of the application. We initially develop four static (i.e., periodic) approaches and compare them against two state of the art dynamic protocols, showing that our approaches are capable of supporting the application even in heavily dense scenarios. Then, we propose a dynamic protocol that further improves the application (increasing safety) and the network layer (reducing resource usage) performance.
The final contribution is a platooning control algorithm that, compared to state of the art approaches, is re-configurable at run-time and that can be adapted to network conditions. We thoroughly test the algorithm in highly challenging scenarios. These scenarios include a realistic network setup where the road is shared by human- and automated-driven vehicles. Human-driven vehicles interfere with automated-driven ones by sending data packets on the same channel. Moreover, we also consider a scenario with realistic vehicle dynamics, which takes into account vehicles’ engine and braking characteristics. The algorithm is shown to be robust to network and external disturbances, to have a fast convergence, and to be very stable.
The results in this work thus represent a big step towards the real world implementation of platooning systems
Studying «too much»? A comparative and diachronic analysis of overeducation among tertiary graduates.
No full textThe aim of this dissertation is to assess if and how institutional features are likely to shape fields of study differentials in the overeducation risk.
This issue is addressed with two different perspectives. First it is comparatively analysed how the differential incidence of overeducation among graduates from different fields of study is affected by labour market institutions.
Then the effect of the university reform dictated by the guidelines of the Bologna Process on tertiary graduates’ risk of overeducation is evaluated. Italy is selected as a relevant case study for these analyses since, in comparison with other developed countries, it displays both low graduation rates and modest returns to tertiary education
Dynamical properties of Bose-Bose Mixtures
Get PDFIn this Thesis is presented a study on dynamical properties of mixtures of ultraold Bose gases. The behaviour of this system in different regimes is analysed: with and without coherent coupling between the two components, in homogeneous and harmonic shaped trapping potentials and in different dimensions and geometries. Most of the results presented here have been obtained by means of numerical solutions of coupled Gross-Pitaevskii equations and have been compared with theoretical predictions (and sometimes experiments), describing the same phenomena. In particualr the stability of persistent currents in a two-component Bose-Einstein condensate in a toroidal trap is studied in both the miscible and the immiscible regime. In the miscible regime we show that superflow decay is related to linear instabilities of the spin-density Bogoliubov mode. We find a region of partial stability, where the flow is stable in the majority component while it decays in the minority component. We also characterize the dynamical instability appearing for a large relative velocity between the two components. In the immiscible regime the stability criterion is modified and depends on the specific density distribution of the two components. The effect of a coherent coupling between the two components is also discussed. A study on the collective modes of the minority component of a highly unbalanced Bose-Bose mixture is also presented. In the immiscible case we find that the ground state can be a two-domain walls soliton. Although the mode frequencies are continuous at the transition, their behaviour is very different with respect to the miscible case. The dynamical behaviour of the solitonic structure and the frequency dependence on the inter- and intra-species interaction is numerically studied using coupled Gross-Pitaevskii equations. The results of the study on the static and the dynamic response of coherently coupled two component Bose-Einstein condensates due to a spin-dipole perturbation is also sown. The static dipole susceptibility is determined and is shown to be a key quantity to identify the second order ferromagnetic transition occurring at large inter-species interactions. The dynamics, which is obtained by quenching the spin-dipole perturbation, is very much affected by the system being paramagnetic or ferromagnetic and by the correlation between the motional and the internal degrees of freedom. In the paramagnetic phase the gas exhibits well defined out-of-phase dipole oscillations, whose frequency can be related to the susceptibility of the system using a sum rule approach. In particular in the interaction SU (2) symmetric case, when all the two-body interactions are the same, the external dipole oscillation coincides with the internal Rabi flipping frequency. In the ferromagnetic case, where linear response theory is not applicable, the system shows highly non-linear dynamics. In particular we observe phenomena related to ground state selection: the gas, initially trapped in a domain wall configuration, reaches a final state corresponding to the magnetic ground state plus small density ripples. Interestingly, the time during which the gas is unable to escape from its initial configuration is found to be proportional to the square root of the wall surface
tension
Anaerobic side-stream reactor: a sustainable solution for sewage sludge reduction
Get PDFOver the last two decades, the production of excess sludge has increased rapidly due to a more
stringent legislation on effluent quality and a growing number of new plants, becoming an
economic and an environmental critical issue. Processing excess sludge could account for half up
to 65% of the total operation costs of a wastewater treatment plant. Technologies to reduce the
excess sludge had been widely studied. Several studies reported that the technologies integrated in
the wastewater handling units should be cost effective and preferable rather than the techniques
integrated in the sludge handling units, as they allow to reduce the sludge production rather than
treat it. Thus, the development and the optimization of a technology able to reduce the sludge
production in the water line is now challenging. A lot of technique have been developed such as
biological, thermal, high temperature oxidation, mechanical treatments, ultrasonication, ozonation
or by using chemical compounds. Some of these have been proven not energy saving, while others
can negatively affect the effluent quality of the process due to the formation of by-products.
Among others, biological treatments are a challenging strategy for sludge reduction. In recent
years, several studies showed that including an anaerobic bioreactor in the returned activated
sludge line of a conventional activated process could significantly enhance the sludge reduction
without causing negative effects on operational performances. Today, this configuration is known
as anaerobic side-stream reactor (ASSR) process. Several laboratory applications highlighted that
the sludge yield of the ASSR process could be reduced up to 60% compared to a conventional
activated process. Despite the highest percentage of sludge reduction achieved, the process is still
little applied to real scale because its main operating parameters and sludge reduction mechanisms
are still unclear.
This study focused on the verification of ASSR process, the mechanisms of sludge reduction
and the microbial structure of the process. During the first part of the research, a laboratory
experimental system was designed and implemented. A sequencing batch reactor (SBR), to
simulate the water line of a real wastewater treatment plant, and an ASSR as a sludge treatment
unit composed the system. Unlike most of the previous studies, the system was fed with real urban
wastewater in order to obtain results that reflect as much as possible what can really happen to a
municipal WWTP. Through a critical analysis of the literature, the influence of two important
operating parameters, such as the solid retention time (SRT) of the ASSR and the interchange rate
(IR), which means the percentage of biomass cycled into the ASSR, had been uncovered
Given this, the experimental system was started up and reached a stable condition after 60 days.
The research was developed in three different phases that lasted for about 90 days each. The
experimental lab system was tested under three configurations: i) 10% sludge interchange rate and
SRT in the ASSR of 10 days; ii) 20% sludge interchange rate and SRT in the ASSR of 5 days and
iii) 40% sludge interchange rate and SRT in the ASSR of 2.5 days. The observed sludge yield
(Yobs) of each phase was evaluated and was equal 0.21 g TSS/g COD, 0.14 g TSS/g COD and
0.12 g TSS/g COD in Phase I, II and III, respectively. These results confirmed that the process
could significantly decrease the sludge production and a reduction up to 62% could be achieved.
To explain the results obtained in terms of sludge reduction, different tests and analysis were
performed. The release of soluble COD and ammonia in the ASSR have highlighted that the
endogenous decay and cell lysis mechanism occur in the ASSR. Extraction of EPS, with CER and
BASE methods, showed a release of protein and polysaccharides in the bulk solution that
increased passing between Phase I and III. At the end of each experimental phase, batch tests were
carried out to evaluate the activity of phosphorus accumulating organisms (PAO) and denitrifying
phosphorus accumulating organisms (DPAO).
Recirculation in SBR-ASSR selects DPAO microorganisms. This was a result of great interest
because DPAO could enhance the biological nutrient removal since nitrogen and phosphorus can
be simultaneously removed. Furthermore, DPAO has lower cell yield than PAO resulting in lower
sludge production. Results showed an activity of PAO, DPAO and other slow growers such as
sulfate reducing bacteria. All these results suggested that the high percentage of sludge reduction
could be explained as a combination of aspects, such as the cell lysis, the cryptic growth, the
selection of slowing microorganisms and EPS destructuration. The SRT and the IR could be
considered as main parameters and their variation could significantly affect the performance of the
process. Microbial analyses were carried out to investigate the bacterial and archaeal structure of
the ASSR sludge during each phase.The results confirmed the presence of several bacteria that
are typically heterotrophic responsible of hydrolysis and fermentative process of organic matter.
Several slow growers bacteria were also detected. Moreover, according to the batch tests on PAO
and DPAO activity, a relevant increase in Phase III of some genera able to enhance the biological
phosphorous removal has been observed.
In summary, the research found that the ASSR process is a sustainable solution for the sewage
sludge reduction due to an efficient and a low sludge production, able to ensure both carbon,
nutrients and phosphorous removal applying an extremely simple technology, easy to realize both
in new and in existing wastewater treatment plants
The relationship between genotype and phenotype in cell-free transcription-translation reactions.
No full textCell-free transcription and translation reactions lie at the heart of the rising field known as in vitro synthetic biology and their existence is fundamental for the reconstitution of artificial cells. While researchers are exploring different ways to create such reactions, the common feature that they share is the use of a template DNA to carry the information for the specific function that the reaction is required to perform. The scope of this thesis is to elucidate the relationship between the genotype and the phenotype in such reactions, investigating both transcription and translation using state of the art fluorescence spectroscopy
Long term morphodynamics of alternate bars in straightened rivers: a multiple perspective
No full textAlpine rivers have been regulated to claim productive land in valley bottoms since the last two centuries. Width reduction and rectification often induced the development of regular scour-deposition sequences, called alternate bars, with implications for flood protection, river navigation, environmental integrity. Understanding how alternate bars evolves in rivers and defining the key aspects that influence the development of these regular deposits of sediments represents a challenge that is not fully described. Most studies on alternate bars are in fact based on mathematical theories, laboratory experiments and recently numerical simulations, but only few studies on field cases have been performed so far. The goals of this work are: i) to quantify the morphodynamics of alternate bars in the Alpine Rhine River, with a particular emphasis on bar migration; ii) to assess to what extent the predictions of analytical bar theories are consistent with field observations and to explore how theories may help interpret observed alternate bars dynamics; iii) to determine the ability of a numerical model to simulate correctly the formation and the length scale of alternate bars and influence of different multi-decadal inflow conditions. The 42-km chosen reach is located along the border between Austria and Switzerland, between the confluences of Landquart and Ill rivers. The whole reach has been completely embanked starting from the 19th century, so alternate bars are present for more than a century. Moreover the simplification of the cross section, together with the presence of only few bends, puts the Alpine Rhine in the ideal position to be compared with analytical theories of alternate bars in straight channels.
The goals are achieved by analyzing a dataset of freely available Landsat imagery, which combine unprecedented temporal length (3 decades), spatial length (more than 400 channel widths) and temporal resolution (around 3 images per year). Bars show a spatially selective behavior, with short, bars occurring in distinct straight reaches with respect to longer bars. The same evidence is found in terms of bar migration, so that short bars are shown to migrate
more than longer bars, in agreement with theoretical predictions. A full range of bar wavelengths and more complex patterns occur in reaches with bends and ramps. Bar height, obtained from cross section monitoring, was
found to be much more uniform. The temporally long dataset, including approximately 30 floods with different magnitude and duration, allowed the investigation of bar migration as a function of discharge, showing that bars migrate faster for intermediate foods. Predicted values of linear theories for free and forced bars in straight channels are in good general agreement with field observations, when considering conditions of bar formation and bar wavelength. Comparing theories and observations suggests that theoretical outcomes may represent the boundaries of the actual, wide range of bars’ behaviour, which likely reflects non-linear interactions, flow unsteadiness, sediment size hetero-
geneity and finite length of straight reaches, which are not retained in linear theories. Non-linear interactions are investigated through the 2D numerical morphodynamic model Basement, developed at the Swiss Federal Institute of Technology of Zurich. Preliminary investigations focus on the role of the transversal sediment transport, that behaves as a diffusive term. The numerical diffusion can be indirectly evaluated starting from the calibration of the coefficient of the diffusive term and a benchmark methodology to
evaluate the lateral and numerical diffusion is defined. The results are used in the morphological calibration of the model. The spatial trend of wavelengths is in general agreement with the field data, and the migration take place mainly in correspondence of short bars, while long bars tend to elongate with time. The choice of a constant discharge or a real hydrograph influences the time scale of bar evolution.
The present analysis results in the longest spatial and temporal field case study of river bars in channelized rivers with a temporal survey resolution that allows the investigation of the effect of individual flood events,
and provides new quantitative data on bar wavelength and migration. The dataset provides useful information to assess the applicability of analytical bar theories, so far mainly tested against flume experiments, and following recent attempts in French and Dutch streams. Moreover, a novel
two-dimensional morphological benchmark to access the role of numerical diffusion is proposed. The new insights are crucial to design future management scenarios accounting for hydraulic safety and environmental quality
Adaptive exoskeleton for the integrated retrofit of social housing buildings
No full textThis doctoral thesis presents technical strategies for the rational maintenance of the building heritage directed
at the integrated retrofit of social housing stocks.
The study comprised the analysis of recovered residential buildings in order to develop new sceneries to adopt
in critical situations, leading to the definition of a new experimental practice called “adaptive exoskeleton”.
This strategy involves the wrapping of the entire original building with a three-dimensional structural envelope,
the exoskeleton, using a construction process able to limit interferences on the use of the building and on the
life of its inhabitants. The exoskeleton is an independent frame, carefully designed at the joint-scale to achieve
awareness of the constructive sequence and of the optimization of the resources. Dry construction technologies resulted to be the most effective, because based on the principles of lightness and reversibility, and because they allow to realize a structural grid able to satisfy different standards in relation to the changing user conditions.
The strategy of the adaptive exoskeleton, which exploits optimized and industrialized components, appears
convenient in relation to large-scale interventions on the built heritage and, at the same time, it is
architectonically versatile, with many possible options adaptable to different cultural contexts. The structural frame can be adjusted to different dimensions, extensions, typologies and technologies, maintaining the same basic characteristics. Passive dissipative devices realized with shape memory alloys, strategically located as connectors with the existing building, are used in order to reduce the lateral displacements during earthquakes. A key idea is the separation between the long lasting elements of the construction, such as the structural systems, and the parts that can be updated progressively in relation to the requirements of the user or to the technological innovations. This principle is convenient in large-scale campaigns, where it is necessary to create a solid base structure without renouncing to the individualization and the variety of the demand, which stimulates the introduction of architectural components with a shorter use-life.
The structural characteristics of this construction and its ability to dissipate the seismic input, were analysed
during a research period of twelve months undertaken at the Eindhoven University of Technology (Netherlands) at the unit of Innovative Structural Design of the Built environment department. The verification phase considered two building typologies, due to their high diffusion in Europe: the use of the finite element software SAP2000 required the application of a “frame model” for masonry buildings and of a “strut model” for the concrete frame with masonry infill.
The seismic behaviour of the buildings was analysed before any intervention and after the introduction of the
adaptive exoskeleton implemented with shape memory alloys-based devices. The experimental phase was also undertaken with reference to San Bartolomeo estate in Brescia, Italy.
Summarizing, the research underlined the convenience of applying retrofit processes in opposition with
demolitions and reconstructions, above all in terms of social and environmental costs. The adaptive exoskeleton, in particular, provides an integrated and synergic solution because while improving the seismic behaviour of the structure, offers additional space for services and functions, increasing the economic value of the building and improving its energy performances and its architectural characteristics
Global development, acoustic and emissive consequences of hydropower
No full textIncreasing energy demand driven by rapid population and economic growth, the need for climate change mitigation, and the depletion of fossil fuels is stimulating the search for renewable, climate neutral energy sources. Hydropower provides an efficient, low maintenance and flexible form of energy, which can provide ancillary benefits such as flood control, water storage and job creation. Yet, the construction of dams for hydropower production has been recognised by scientists as one of the major threats to the ecological integrity of river systems. For instance, the fragmentation of river systems alters the flow, thermal, and sediment regimes of rivers, and restricts the free movement of aquatic organisms. Disruption to the natural flow regime results in the degradation of physical habitat features which generate acoustic stimuli that are relevant to organisms. In addition, initial flooding of terrestrial habitats results in the rapid decay of organic matter, which releases greenhouse gases (GHG) into the atmosphere. Conservation and management of river systems therefore requires a greater understanding of the processes and mechanisms which underpin the ecohydrological impacts of hydropower. In this context, this doctoral thesis aims to investigate: (i), the ramifications of a global boom in hydropower construction, (ii) the prediction of GHG emissions from hydropower reservoirs, and (iii) the temporal and spatial changes in underwater river soundscapes affected by hydropower. Researchers have investigated the social, economic and ecological consequences of reservoir construction for decades. However, the lack of coordinated, georeferenced databases has hindered catchment decision making, and limited the development of regional and global research in particular. In Chapter 1, the primary objectives were to create a high resolution, georeferenced database of hydropower dams under construction or planned to assess the dimension and spatial distribution of hydropower developments, their density relative to available catchment water resources and the future impact on river fragmentation. Data were collected on hydropower schemes under construction or planned with a capacity of 1 MW or above, from government and non-government databases, grey literature and news reports. Spatial analyses were conducted in a geographical information system (GIS) on the extent of global development, impact per water availability and potential consequences for existing status of river fragmentation. The relative contribution of hydropower reservoirs to the global GHG budget, particularly in sub-tropical and tropical regions, remains the subject of intense critical debate. The initial objective of the second study was therefore, to identify principal parameters and underlying processes that drive GHG emissions from reservoirs. The second step was to review global reservoir emission measurements and their source pathways in hydropower systems. Meteorological and landscape derived parameters were then correlated with the GHG measurements in order to assess if and which selected parameters might explain variations in GHG emission data. Similarly, existing empirical models were applied to the measured data to assess their suitability in predictive modelling. Finally, a newly developed process based model (FAQ-DNDC v1.0) was used to simulate ‘net’ CO2 emissions from a newly flooded tropical reservoir and compared to the measured results. The final study (Chapter 3) examined the influence of hydropower systems on the underwater acoustic properties of river habitats. Using recently developed acoustic sensors in addition to traditional hydrophones, the study characterised the temporal and spatial changes in river soundscapes affected by hydropeaking, compared their frequency composition to unaffected river soundscapes, and critically appraised the ecological implications. The results of Chapter 1 indicate that we are now experiencing an unprecedented growth in global hydropower construction. Over 3,700 dams are planned or under construction, primarily in Africa, South America and East Asia. The expansion in dam building will reduce the number of free flowing rivers on a global scale by approximately 21%. The results of Chapter 2 show that variation in measured emissions due to the inherent heterogeneity of the underlying processes, in addition to methodological limitations, impede the prediction of GHG emissions. Source pathways of CO2 are similar for the majority of systems, however, pathways of CH4 emissions are highly variable and dependent on local operating conditions and the configuration of the given hydropower system. A newly developed process based model (FAQ-DNDC v1.0) shows that a mechanistic approach may provide the basis for the ‘net’ assessment of future hydropower reservoirs. Chapter 3 reveals that distinct river soundscapes undergo changes which are highly correlated to hydropower operations, and thus rapid sub-daily changes occur at timescales not often found in natural systems. These changes occur mostly in low frequency bands, which are within the range of highest acoustic sensitivity for fish. In pool habitats affected by hydropeaking, sound pressure levels in the lower frequencies (~0.0315 kHz) may increase by up to 30 decibels. Similarly, sound pressure levels of riffles increase by up to 16 decibels in the low to mid frequencies (~0.250 kHz). Overall, the findings of this thesis have a number of implications for river catchment management. Hydropower construction is taking place in some of the most ecologically sensitive areas of the globe, thus, this research provides a timely contribution to:
(i) Provide a foundation for future research at catchment, regional and global scales. For instance, systematic conservation based planning is required to designate ‘no go’ areas to promote the long-term survival of biodiversity. Strategic positioning of future dams or reconfiguration of existing hydropower systems may reduce the combined impacts on biodiversity and GHG emissions without losing power capacity.
(ii) Assess driving parameters of GHG emissions, critically appraise current predictive GHG emission models and use a process based approach to simulate ‘net’ emissions from a sub-tropical reservoir. Future reservoirs will sequester, mineralise and emit an increasing quantity of carbon to the atmosphere, and subsequently, will take a greater role in the global GHG budget. This research concludes that, in some cases empirical models may not be suitable for making robust estimations of future GHG’s from hydropower reservoirs. Combining the underlying carbon cycling processes within a process-based model allows the estimation of ‘net’ CO2 emissions from hydropower reservoirs. This approach may be integrated by catchment planners into the future lifecycle assessment of hydropower reservoirs.
(iii) Characterise acoustic changes in underwater sound in rivers affected by hydropeaking. The findings emphasise that flow regulation by hydropower results in rapid changes to the amplitude and frequency spectrum of the riverine acoustic environment. These changes persist for longer periods than other forms of anthropogenic sound and may have implications for the whole biota. Thus, future studies should focus on measuring the behavioural and physiological impact on riverine organisms in order to develop guidelines for hydropower licensing
A multicriteria perspective to integrate environmental management and environmental accounting in the tourism industry. The case of Small and Medium-sized Hotel Enterprises (SMHEs) in the Alpine Province of Trento
No full textThe environment, understood as the biophysical support to human society and economic systems, is a relevant variable to firm management. The way the environment is managed can affect not only firm competitiveness but also firm environmental performance both in the short and long-term. The environment generates the inputs (in terms of stocks of natural capital and flows of ecosystem services) supporting human economy and receives back outputs and by-products (waste and emissions) generated by human activities. Therefore the environment does a constant work providing inputs and receiving outputs throughout each function and businesses phase of firms, playing a key role for their development and sustainability. This thesis examines the following two main issues: 1) how to apply environmental management theory in the context of tourism industry, and 2) how to assess the environmental performance and sustainability of Small and Medium-sized Hotel Enterprises (SMHEs) by using a multicriteria assessment framework. Both a specific economic sector and different type of firms are investigated: the tourism industry and selected SMHEs in the Province of Trento. The environmental management theory, through an online survey of SMHEs in the Province of Trento, explores the implementation of environmental practices, the characteristics of enterprises as environmental determinants and the motivations and perceptions to environmental commitment. Environmental accounting is instead employed to assess environmental costs and impacts associated to selected hotels in the Province of Trento