Università degli Studi del Sannio
  • Benevento, Campania, Italy
Recent publications
In this paper, we report on the development and field test of a fiber optic seismic hydrophone. The seismic hydrophone was designed to offer performance suitable to operate with resolution down to the sea state zero in underwater environments. The sensing configuration exploits a fiber coil interferometer in Michelson configuration, wrapped around a sensitive composite cylinder. The materials and the size of the hydrophone were selected by numerical analysis in order to guarantee the desired responsivity. The sensing system was integrated in the seismologic monitoring system of the Campi-Flegrei caldera for demonstrating the operative capability of the developed system. To this aim, the hydrophone was installed in a submarine module onto the seabed in the Gulf of Pozzuoli and the optoelectronic read-out system was placed on an instrumented geodetic buoy. During the field trials, we detected several earthquakes occurred in the area and compared the results with a reference piezoelectric hydrophone. The seismic sequence was used to retrieve the sensor responsivity in the frequency range 1-80 Hz. The sensing system reaches a responsivity of about − 300 nm/Pa and exhibits an average noise floor level down to 100µPa/√Hz. The comparison of the traces recorded by the optical and reference hydrophones reveals a high level of similarities with autocorrelation higher than 85 %. The reported field trial at the Campi-Flegrei caldera demonstrates the capability of optical fiber hydrophones to operate in relevant environments for seismological monitoring.
To promote the integration between solar-driven torrefaction, Power-toGas , and Chemical Looping Combustion (CLC) systems, this work numerically analyzes the performances of a novel process layout. Several agro-industrial residues were considered as fuels. CuO supported on zirconia and Ni supported on alumina were considered as oxygen carrier and methanation catalyst, respectively. Torrefied samples were purposely obtained by means of experimental runs carried out for 30 min at 300 • C in a lab-scale fixed bed reactor under a nitrogen atmosphere. Under the adopted conditions it was attained an increase in the lower heating values (LHV) of the selected feedstocks by about 14-49 %, depending on the different composition and reactivity of the parent biomass. Based on these data, it was estimated that, with respect to 10 kg h − 1 torrefied biomass fed to the CLC system, a total thermal power production in the range of 28-58 kW can be achieved. CO 2 conversion degrees of above 98 % were evaluated for the methanation unit in all considered scenarios. Considering different locations in Italy, PV field sizes ranging from 45 m 2 up to 1392 m 2 were evaluated for the solar-driven torrefaction unit. Wider sizes were calculated for the hydrogen production one, ranging from 3366 m 2 up to 5598 m 2. Eventually, an electric energy storage efficiency of around 16 % was assessed for the proposed layout. Finally, it was found that moving from the adopted torrefied feedstocks to the produced gaseous fuel, an increase in the LHV by about 44-55 % can be attained, while concurrently, CO 2 emissions are favorably decreased by 98 %.
The assessment and monitoring of structures through in situ tests, especially dynamic tests, is becoming a common procedure due to the evolution of the instruments and numerical processing of data. However, the use of the data based on the supervised approach, which requires engineering knowledge of the structure is needed before assessing the numerical model that will be the “digital twin” model of the construction for future analysis, monitoring and upgrading of the structure. This process is very complex and requires strong competence in the field of structural engineering, but it allows a real reference for the periodic check of the structure health with a method to also define a solution for its maintenance and upgrade. In this paper, a case study of a PC bridge designed by Riccardo Morandi in 1952–1955 is proposed to apply the process of updating a numerical model by static and dynamic in situ tests. The process based on the two different types of tests was separately conducted to evaluate the efficiency and the difference in the results. The main results of the two types of tests overlap for most features, but specific evidenced aspects that are observed have to be considered.
Background Mesoplastics (5–25 mm) and microplastics (0.001–5 mm) are emerging pollutants of great concern. However, reliable methods of monitoring these types of plastic in river ecosystems have not yet been established. The goal of this work was to evaluate, for the first time, the suitability of Fontinalis antipyretica as a biomonitor of meso- and micro-plastics in rivers. With this aim, native samples of the moss and devitalized moss clones, held inside the bags, were compared for the uptake of fluorescent polystyrene particles under laboratory conditions, and for retention of plastic debris in the field, in sites close to wastewater treatment plants. Results In the laboratory experiment, the moss retained smaller microplastics, and a higher number of polystyrene meso and microplastics was counted in the moss bags than in the native moss. In the field study, the moss retained plastic debris chiefly in the form of fibres regardless of the capacity and flow rate of the wastewater treatment plants affecting each sampling site. The uniform morphology of moss clone seems to affect the retention of this type of pollutant. The FTIR analysis confirmed the particles entrapped by the moss bags as plastic, specifically polyethylene and polyamide type 6, among the most common plastic polymers detected in rivers. Conclusions The study findings highlighted the value of using uniform material, as the clone exhibited a greater accumulation efficiency with respect to the native moss. The mesh bags could act as selective filters and/or prevent the loss of adhering plastics. In the field, the bags favour plastic fibres retention despite the river flow. Finally, although FTIR is useful for the identification of plastic type, it is not very sensitive when small quantities of ground samples are used.
This paper describes a study on log mining in the domain of microservices technologies. We focus on the detection of anomalies from logs, i.e., events requiring deeper inspection by analysts. Log mining is challenging in microservices systems due to the high number of heterogeneous logs. We present Micro2vec, a novel approach to mine numeric representations of computer logs without making assumptions on the format of underlying data and requiring no application knowledge; representations computed by Micro2vec are suited for anomaly detection. To cope with the lack of publicly-available datasets of labeled logs from production systems, we validate our approach by means of a mixture of direct measurements from logs, one-class classification experiments and generation of log variants. The study has been conducted in the context of a Clearwater IP Multimedia Subsystem setup consisting of microservices deployed in Docker containers, and on a real-world critical information system from the Air Traffic Control domain, which implements a communication model typically used with microservices.
The ongoing climate crisis leads to develop smart communities with zero net emissions, and the Responsive Building Envelopes (RBEs) have a crucial role for the goal to be achieved. In this frame the smart windows are promising building envelope solution. With respect to conventional static windows, on one hand they could reduce the building thermal loads and therefore lead to an energy saving and to an improvement of the thermal comfort, on the other hand they could reduce the possible glare, improving the also the visual comfort. There are some smart windows based on widespread technologies and deepen investigated in the scientific literature, such as the electrochromic solution, but there are some others, such as liquid crystal devices, not really investigate, or characterized only by means of simulative analysis, often without calibrated models with experimental data. Thus, the present study aims to investigate, under experimental and numerical point of view, an electric-driven window with liquid crystal technology installed in a full-scale facility located in a Mediterranean climate. A calibrated numerical model is carried out and different windows control logics and future climate projections (to 2050s and 2080s) are analyzed. Among different control logics, the one depending on daylight illuminance level on the work plane shows the best performance, with a total energy saving (lighting and cooling) of -3% with respect a static window in clear state.
This work experimentally and numerically investigates the thermal performance of a vertical shell-and-tube heat exchanger, filled with a biological phase change material (PCM), linked to a water-chiller system for cold thermal energy storage. The system provides the cooling service to a 150 m2 single-family house. An experimental apparatus has been designed to collect the PCM temperature data through the employment of multiple thermocouples located at different heights of the heat exchanger. Starting from the experiment, a comprehensive 3D numerical model of the system has been developed based on the enthalpy-porosity method using COMSOL Multiphysics®. The PCM temperature profiles and the evolution of the solid-liquid interface location at various time instants are used as performance indicators of the model reliability and accuracy. The numerical agreement with the experimental findings is proved using statistical indices, e.g., maximum values of mean absolute error (MAE) and root mean square error (RMSE) equal to 1.18 °C and 1.33 °C, respectively, with regards to central thermocouples. The results reveal that natural convection highly affects the PCM charging/discharging processes, as proved by the PCM liquid fraction, which moves from full to 51 %, between two levels spaced by 0.78 m. The developed 3D model, based on the enthalpy-porosity method, allows to consider boundary conditions variability with both angle and height, which are not usually covered by simplified 2D models. Hence, this model confirms that only 39 % of the PCM mass experiences the complete phase change process, proving that the current design does not allow the PCM to totally exploit the thermal storage potential, thereby making optimization pivotal and challenging.
The Lab-on-Fiber technology is giving an important contribution to the development of compact and minimal invasive devices for biomedical applications. By exploiting the high degree of miniaturization combined with the biocompatibility of the materials used, these devices can be integrated inside medical needles and taken in the human body for in vivo diagnosis and treatments, with important advantages in terms of performances, effectiveness and invasiveness. In this framework, with a look toward high-resolution ultrasound based imaging, here we analyze a novel Lab-on-Fiber 3D micro-structure for ultrasound detection, consisting in a polymeric membrane sustained by six pillars, directly integrated above the tip of a standard single mode fiber. Such a structure essentially works as a Fabry-Perot cavity, providing interference fringes in the fiber reflection spectrum, which shift accordingly with the structure vibrations caused by the incident acoustic waves. Our numerical studies, based on finite element method, demonstrated that by opportunely dimensioning the geometrical parameters involved it is possible to tune the working frequency range up to tens of MHz, reaching sensitivities higher than the standard configurations proposed so far, given by a polymeric slab directly attached above the fiber tip. Interestingly, the investigated structure can be effectively realized by exploiting the Two-Photon polymerization technique directly applied to the optical fiber tip.
The advent of the COVID-19 pandemic led to an economic crisis of the construction industry and to an increasing of energy consumption in the residential sector for all the world. The European Union highlights the crucial role of building sector for both energy gains and economic growth, defining a “Renovation Wave” plan combining regulation, financing and technical support with the aim of greening the buildings, creating jobs and improving lives. In Italy a great support mechanism for energy refurbishment of existing buildings has been launched by means of tax deduction of 110% over 5 years. The present study aims to analyze this new funding mechanism, under energy, environmental and economic point of views. By means of a real case study, representative of highly widespread southern Italy HVAC-building system, it will be highlighting advantages and contradictions of the incentive mechanism developed, proposing possible future improvements. It is found that, if on one hand, the best refurbishment measure under energy/environmental point of view is the external insulation, windows replacement, electric heat pump and PV-system installation, with a global not renewable performance index reduction of 81%, on the other hand it is not the best solution considering the cost/saving ratio.
One of the pivotal steps in seismic assessment of structures is the definition of functional relationships between an Engineering Demand Parameter (EDP) and a ground motion Intensity Measure (IM). This paper investigates the correlation between widely used non-spectral and cumulative-based ground motion intensity measures and corresponding engineering demand parameters for regular and irregular structures as bidirectional single-degree-of-freedom (2D-SDOF) systems. The correlation is investigated under sequential earthquakes in terms of efficiency and sufficiency, considering various seismic incident angles. Structural performance is expressed as maximum inelastic displacement, MD, maximum inelastic absolute acceleration, MA, residual displacement, RD, and hysteretic energy, EH. The results of extensive parametric analyses show that if the MD, MA, EH and RD of regular systems are considered as demand parameters, the optimal IMs in terms of efficiency and sufficiency are vsq, arms, vrs and vsq, respectively.
The purpose of this chapter is to present some examples and applications of the little group method for Abelian extensions.
In this chapter, we fix notation and recall some basic facts of linear algebra, of finite groups and their representation theory.
This chapter is based on (Canad J Math 23:857–865, 1971; Canad J Math 25:1113–1119, 1973) by R. L. Roth. Previous papers with some results on this subject include (J. Fac. Sci. Univ. Tokyo Sec. I 10:129–146, 1964) (Pacific J Math 32:119–129, 1970) by N. Iwahori – H. Matsumoto and G. J. Janusz, respectively. See also Sect. 2.4, where the more general case when G∕IG(σ) is Abelian was studied.
The present and the subsequential chapters are devoted to the study of the induction of unitary projective representations. Our exposition is mainly based on the pioneering work of Mackey (Acta Math 99:265–l311, 1958, Sect. 4). However, Mackey based most of his proofs on Proposition 7.12 (actually, he worked on locally compact groups). When possible, we prefer to give more direct proofs. See also Remark 8.8 below.
In this chapter, we describe the irreducible projective representations of a finite Abelian group: we shall use the Clifford theory from the previous chapter. Then, by means of the machinery developed in Sect. 7.3, we describe the ordinary, irreducible representations of finite metabelian groups. As a particular case, we obtain an alternative description of the irreducible representations of finite 2-step nilpotent groups (cf. Sect. 6.6).
In this chapter we study the representation theory of the class of groups G with a normal subgroup N such that the following conditions are satisfied: $$\displaystyle \begin {aligned}{} &\text{(1) }A \mathrel{\mathop:}= G/N \text{ is Abelian;}\\ &\text{(2) every }\sigma \in \widehat {N}\text{ has an extension }\widetilde {\sigma }\text{ to }I_G(\sigma ). \end {aligned}
In this chapter, we establish some basic facts on Clifford theory for induced projective representations. We follow quite closely the exposition for the case of ordinary representations in Chap. 2 and we give the first applications of the theory. Another fundamental application is in Sect. 10.2 on irreducible projective representations of finite Abelian groups.
In this chapter, we establish some basic facts on Clifford theory for induced representations from a normal subgroup and we give the first applications of the theory.
In this chapter we treat central extensions of groups, a particular case of the construction in Sect. 1.5, and we give a complete cohomological characterization of these. Following Mihailovs (The orbit method for finite groups of nilpotency class two of odd order. Preprint: arXiv.org: math.RT/0001092) and Kokhas (J Math Sci (NY) 131(2):5508–5555, 2004) with a 2-step nilpotent group with 2-divisible center we associate a 2-step nilpotent Lie ring. This is a key construction for the definition and application of the orbit method.
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741 members
Eugenio Zimeo
  • Department of Engineering (DING)
Luigi Troiano
  • Department of Engineering (DING)
Massimiliano Di Penta
  • Department of Engineering (DING)
Mario Luca Bernardi
  • Department of Engineering (DING)
Information
Address
Piazza Guerrazzi, 82100, Benevento, Campania, Italy
Head of institution
Prof. Gerardo Canfora
Website
www.unisannio.it