Propulsive landing of launchers’ first stages with Deep Reinforcement Learning

The planetary landing problem is gaining relevance in the space sector, spanning a wide range of applications from unmanned probes landing on other planetary bodies to reusable first and second stages of launcher vehicles. In the existing methodology there is a lack of flexibility in handling complex non-linear dynamics, in particular in the case of non-convexifiable constraints. It is therefore crucial to assess the performance of novel techniques and their advantages and disadvantages. The purpose of this work is the development of an integrated 6-DOF guidance and control approach based on reinforcement learning of deep neural network policies for fuel-optimal planetary landing control, specifically with application to a launcher first-stage terminal landing, and the assessment of its performance and robustness. 3-DOF and 6-DOF simulators are developed and encapsulated in MDP-like (Markov Decision Process) industry-standard compatible environments. Particular care is given in thoroughly shaping reward functions capable of achieving the landing both successfully and in a fuel-optimal manner. A cloud pipeline for effective training of an agent using a PPO reinforcement learning algorithm to successfully achieve the landing goal is developed

Digital supply chains for ecosystem resilience: a framework for the Italian case

Contingency where exogenous and dramatic factors (i.e. Covid) impact not only on political and social life but also on economy is changing the way business is managed. Grounded on recent works studying the relationship between digitalisation and resilience, this work aims to systematize the links between the two dimensions at Supply Chains (SC) and at ecosystem level. A conceptual framework for manufacturing companies and policy makers is proposed to cope with disruptions thanks to digital technology implementation. The work is based on the results of an explorative analysis held with the support of practitioners from the manufacturing sector, IT providers and policy makers in Italy to systematise results and to demonstrate that public–private partnership can help to face disruptions. This paper contributes to the theory of ecosystems to establish a systemic framework to go beyond the border of each SC proposing a cross-collaboration model

Concerning the spiritual in architecture. Four churches by Carlo De Carli

By comparing four buildings designed by Carlo De Carli in the decade starting in the mid-1950s, this essay aims to develop a perspective on the architecture of sacred spaces that is also peculiar to a way of meaning architecture in a broader sense. Carlo De Carli, their designer, was a key but little-studied figure in Italian post-war architecture. In his work, he was able to interweave theoretical reflection, publicist activity, design practice, teaching, and the promotion of artisanal production structures into a unified vision of architecture as a spiritual quest. The churches that he designed (Sanctuary of Our Lady of Tears, Syracuse, 1956-1957; St. Biagio, Monza, 1960) and built (St. Ildefonso, Milan, 1955-1956; St. Girolamo Emiliani, Milan, 1963-1965) are the paradigmatic realization of an idea of architecture that embodies the most profound sense of the communities that inhabit it, showing it as an element of value in the social, urban, cultural, economic contexts with which it interacts. By studying the original materials in the Archives (kept at the Polytechnic of Milan, Diocese of Milan and Parish of San Biagio Monza) and redesigning the projects, the essay aims to interweave De Carli's thought with a reading of the formal dynamics underlying his architecture. Thus, it intends to verify his fundamental idea that architecture is born imbued with life experiences, which it welcomes and of which it's concrete built forms (space, matter, light, and colour) become a true analogue, a revealer of meanings and an authentic donation of sense, bringing out a point of view on architecture for the sacred, but also on architecture tout court, that is still of topical value both in the practice of the project as in its teaching

Reference-free distributed monitoring of deflections in multi-span bridges

The research presented herein pertains to developing a reference-free technique for monitoring bridge deflections under operational conditions. The method is based on monitoring the distributed strains along the length of bridges and employing the Inverse Finite Element Method (iFEM) to compute the deflection for the entire length of bridges. Distributed sensing of strains was achieved by a Brillouin Optical Time Domain Analysis system (BOTDA). The dynamic strains were then used in the iFEM algorithm to calculate the deflections of the structure. This approach computes structural displacements by a variational principle with minimal computational cost. Because of its independence from loads and material properties, the proposed methodology monitors the dynamic deflections during bridge routine traffic operations, and it is potentially viable for real-time monitoring. The approach is validated through two comprehensive case studies, including a laboratory experiment and a field application on a multi-span concrete bridge

Direct and indirect assessment of the elastocaloric properties of cast NiMnTi alloys

The study of the elastocaloric effect of NiMnTi alloys is a key topic for developing materials for sustainable and efficient solid-state cooling and heating applications. In the current work, the mechanical behavior of two arc melted and heat treated NiMnTi alloys with 15 and 18 at% of Ti has been investigated. The effects of heat treatments and operating conditions on the mechanical and caloric properties of the alloys have been assessed through calorimetric analysis, isothermal stress-strain compressive measurements, and adiabatic tests. To evaluate the caloric performance of the NiMnTi alloys, both experimental and theoretical adiabatic temperature changes have been identified, and the isothermal entropy change involved in the stress-induced martensitic transformation has been computed from the discrete integration of the stress-strain curves. The NiMnTi alloys treated at 900 °C exhibited better caloric performance than those treated at 1000°C. Specifically, the sample that achieved the highest experimental positive and negative ΔT values (10.2 °C and −12.6 °C, respectively) was the NiMnTi alloy with 15 at% of Ti and heat treated at 900 °C. This study provides a detailed analysis of the physical properties, functionality, and caloric properties of polycrystalline NiMnTi fabricated through a melting process, considering its potential use in solid-state cooling and heat pumping technologies

Microstructural development via synergic application of Binder jJetting and Quenching and Partitioning (QP) on commercial AISI 4340

This study investigates the microstructural development of commercial low-alloyed AISI 4340 steel through the synergistic application of Binder Jetting and Quenching and Partitioning (QP) processes. The material in the as-sintered condition exhibited significant variations in microstructure and mechanical properties, primarily influenced by the processing route. Carbon content was influenced by the building technique as decarburization was observed at different intensities mainly during the heating stage of sintering, driven by carbothermic reduction. Vacuum-debinding was found to be optimal, leading to the most homogeneous microstructure, predominantly granular bainite with superior hardness and tensile strength. Different QP treatments were optimized considering the decarburization effect on the optimal as-sintered condition, stabilizing 4–8 % retained austenite in a martensitic matrix, with optimal results observed after isothermal holding at either 220 °C or 240 °C for 30 min. These conditions resulted in high UTS values of 1231 MPa and 1151 MPa, respectively, compared to 750 MPa in the as-sintered state. Despite high tensile properties, A% was limited by the presence of residual porosity. This study highlights the critical importance of controlled debinding and sintering atmospheres as well as decarburization-informed QP treatments in achieving desirable microstructural and mechanical properties in additively manufactured AISI 4340 steel components

Towards net-zero: success factors of tertiary building energy efficiency retrofitting projects

The decarbonisation of the building sector requires successful Building Energy Efficiency Retrofitting (BEER) projects. Success Factors are conditions or initiatives that determine project success. In the context of BEER projects possible Success Factors are Energy Efficiency Measures (EEMs) (e.g., installation of heat pumps). Despite their empirical importance, there is a relevant gap in knowledge about the Success Factors of BEER projects. In particular, it is unclear which EEM or combination of EEMs is the most successful in reducing energy consumption and carbon emissions. Addressing this knowledge gap is crucial to improve BEER projects and, therefore, to foster energy efficiency in buildings. Existing literature on Success Factors often focuses on residential buildings and energy efficiency in the industry. Such literature is focused on project management actions (e.g., project controlling and monitoring) rather than on project-related factors (e.g., the specific EEM implemented). In this article, we present and apply a novel method to identify the Success Factors of Building Energy Efficiency Retrofitting (BEER) projects, including EEMs, retrofitting date, building type and incentives. This empirical article is based on statistical and logical analyses (i.e., Fisher exact test and Qualitative Comparative Analysis) of 30 tertiary BEER projects. The results show the building envelope's thermal insulation and the installation of heat pumps as the most relevant single EEMs. However, the results highlight the implementation of combinations of EEMs as a key project's Success Factor. Particularly, findings show a recent implementation of a substantial building envelope insulation and the replacement of gas boilers with new highly efficient heat pumps as sufficient to reach substantial final energy savings in office buildings. Based on the findings, we recommend building owners and contractors prioritise these EEMs, while policymakers support their adoption, boosting BEER projects' success

Per un piano utile

A partire dalla legge di principi per il governo del territorio proposta dall’INU (2023), che ridefinisce organicamente metodo e contenuti del governo di città e territori, il contributo approfondisce e argomenta i tre binomi antinomici, non esclusivi ma virtuosamente concorrenti, che meglio descrivono i caratteri innovativi di un riformato piano urbanistico, al fine di conferirgli l’efficacia, la necessità e l’utilità necessarie per restituire credibilità al metodo della pianificazione: regole vs principi, conformità vs coerenza, prefigurazione vs configurazione