The Cryogenic AntiCoincidence detector for ATHENA X-IFU: a scientific assessment of the observational capabilities in the hard X-ray band

ATHENA is a large X-ray observatory, planned to be launched by ESA in 2028 towards an L2 orbit. One of the two instruments of the payload is the X-IFU: a cryogenic spectrometer based on a large array of TES microcalorimeters, able to perform integral field spectrography in the 0.2-12 keV band (2.5 eV FWHM at 6 keV). The X-IFU sensitivity is highly degraded by the particle background expected in the L2 orbit, which is induced by primary protons of both galactic and solar origin, and mostly by secondary electrons. To reduce the particle background level and enable the mission science goals, the instrument incorporates a Cryogenic AntiCoincidence detector (CryoAC). It is a 4 pixel TES based detector, placed <1 mm below the main array. In this paper we report a scientific assessment of the CryoAC observational capabilities in the hard X-ray band (E>10 keV). The aim of the study has been to understand if the present detector design can be improved in order to enlarge the X-IFU scientific capability on an energy band wider than the TES array. This is beyond the CryoAC baseline, being this instrument aimed to operate as anticoincidence particle detector and not conceived to perform X-ray observations.Comment: Accepted for publication on Experimental Astronom

Distretti industriali e Istituzioni Locali

Nascita ed evoluzione dei distretti industriali Rapporto tra istituzioni e distretti industriali Fattori istituzionali e contesto socio-economico Due casi a confronto: Solofra e Mirandol

Relationships between followers' behaviors and job satisfaction in a sample of nurses

The study investigated two followership behaviors, followers' active engagement and followers' independent critical thinking, and their relationship with job satisfaction in a sample of nurses. In addition, the study also considered a number of control variables and classical job demands and job resources-workload and emotional dissonance for job demands, and meaningful work for job resources-which have an impact on well-being at work. A paper-and-pencil questionnaire was administered to 425 nurses in an Italian hospital, and a hierarchical multiple regression was used to test the hypotheses. In addition to the job demands and job resources considered, followers' active engagement had a significant impact on job satisfaction. Moreover, it showed a significant linear and curvilinear relationship with the outcome variable. Followers' independent critical thinking has a non significant relationship with job satisfaction, confirming the mixed results obtained in the past for this dimension. These findings bore out the importance of analyzing followers' behaviors as potential resources that people can use on the job to increase their own well-being. Looking at followers not just as passive recipients but as active and proactive employees can also benefit the organization

Diseño e implementación de recuperadores de energía en vehículos de transporte

En un vehículo de transporte de pasajeros convencional, sólo un porcentaje muy bajo del combustible, entre el 10 y el 16%, se utiliza para la marcha del mismo mientras que el resto es energía disipada en los frenos, transmisión, motor, accesorios, resistencia a la rodadura, arrastre aerodinámico y ralentí. De todas estas pérdidas, la de mayor magnitud es la del motor (aproximadamente el 63%), la cual en gran medida se pierde en forma de vibración.El propósito de esta tesis, por lo tanto, se centra en el diseño y fabricación de un dispositivo recuperador piezoeléctrico multimodal capaz de recuperar parcialmente la energía que se pierde en la vibración del motor. Esta energía vibratoria disponible está caracterizada por un gran número de ondas mecánicas de diferente magnitud y frecuencia que se excitan para cada velocidad de giro del motor. El diseño se basa en una viga piezoeléctrica compuesta y dos sistemas dinámicos masa-resorte en sus extremos, cuya respuesta dinámica se calcula a partir del desarrollo de un modelo analítico que contempla aspectos distintivos como acoplamiento electromecánico, relaciones constitutivas no lineales, disipación de energía, magnitud de la carga eléctrica, etc.Mediante una apropiada reducción del modelo analítico se identifican los parámetros no lineales correspondientes al modelo. Posteriormente, se fabrican y ensayan cuatro dispositivos, evaluándose el voltaje y la potencia eléctrica dados por el modelo sobre una resistencia de carga. Los resultados obtenidos son validados por los experimentos.En el proceso de optimización del dispositivo de mayor potencia se propone una función objetivo que contempla las características de frecuencia y aceleración variables de la excitación, obteniéndose un dispositivo final superior a los originales, con valores de potencia eléctrica significativos. Finalmente, se realiza la implementación en un escenario real sobre el vehículo, donde se realizan dos recorridos urbanos diferentes para el sensado de temperatura a partir de la alimentación del dispositivo recuperador optimizado.In a conventional transport vehicle, only about 10 to 16% of the energy from the fuel is used to move it down the road. The rest of the energy is lost in the brakes, transmission, engine, accessories, rolling resistance, aerodynamic drag and idle losses. Among all of these, the largest loss is the energy lost in the engine (approximately 63%), which is mostly wasted as vibration. The purpose of this thesis is the design and fabrication of a multimodal piezoelectric energy harvesting device capable of recovering that lost energy. The available vibratory energy is characterized by a large number of mechanical waves of different magnitudes and frequencies which are excited for each speed of the engine. The harvesting device is based on a composite piezoelectric beam with two mass-spring systems at its ends. A one-dimensional analytical model is developed to analyze the dynamic response. Among the distinctive aspects contemplated in the model are: electromechanical coupling, nonlinear constitutive relations, energy dissipation, magnitude of the electric load, etc. By means of an appropriate reduction of the analytical model, the nonlinear parameters corresponding to the model are identified. Subsequently, four devices are fabricated and tested to evaluate the voltage and electrical power over an electrical load, calculated with the analytical model. The results are then validated by the experiments. An optimization process is applied to the device of maximum mean energy by means of the method of genetic algorithms. In order to take into account the principal characteristics of the excitation (variable frequency and acceleration) a proper objective function is proposed. The final device obtained is greatly improved and obtaining a very improvement final device to the original. Significant values of the electrical power are obtained. Finally, the implementation is carried out in a real scenario on the vehicle with considering two different routes trajectories for temperatures measure, from the feeding of using the optimized harvester device as power supply.Fil: Gatti, Claudio David. Universidad Tecnológica Nacional. Facultad Regional Bahía Blanca; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentin

Effect of nonlinearities and objective function in optimization of an energy harvesting device

This work presents a study of the impact of the linearity assumption of the mechanical model in the overall performance of an energy harvesting piezoelectric beam. Also, a brief assessment of geometrical optimization solutions using different objective functions is presented. The mechanical model of the harvester is based on both linear and nonlinear variants of the electrical and mechanical constitutive equations for the piezoelectric material. The nonlinear elastic, damping and electromechanical coupling parameters are obtained via least squares identification using physical experimentation; the experimental tests are performed at different ground excitation accelerations. The computational optimization of the harvester is done using the genetic algorithm implemented in Matlab. Different objective functions are tested, i.e. broadband maximum peak power, maximum power at a particular frequency and broadband mean power; the influence of the selection of each of them in the total recovery of the power of the device is analyzed. The most suitable function to recover the vibratory energy from conventional transport vehicles is found.Fil: Gatti, Claudio David. Universidad Tecnológica Nacional; ArgentinaFil: Ramirez, Jose Miguel. Universidad Tecnológica Nacional; ArgentinaFil: Febbo, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Machado, Sebastián Pablo. Universidad Tecnológica Nacional; Argentin