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Laser intensity noise transfer for pulsed vapor-cell clocks with optical detection
No full textWe propose a signal-theory approach to estimate the contribution from laser intensity noise to the short-term stability of compact atomic clocks based on optical detection. We remove the approximation of white intensity noise, which is usually found in literature, and propose a method for a more faithful estimate, given an arbitrary noise spectrum at the input. This is of fundamental importance, since laser intensity noise is currently one of the main limiting factors of vapor-cell clocks
Current treatments for anal condylomata acuminata
No full textCondylomata acuminate are the most common sexually transmitted disease worldwide. They are usually a serious problem, but it causes emotional distress to patient and physician alike because of its marked tendency to recurrence. The presence of anogenital warts mandates treatment, also for potential degeneration of the lesions
Stati Uniti, così si sono riciclate le fabbriche/2. Il caso di Pittsburgh
No full texturban manufacturing; Pittsburgh; rigenerazione urbana; adaptive reus
Energy dependence of forward-rapidity J / psi and psi(2 S) production in pp collisions at the LHC
No full textWe present results on transverse momentum (p(T)) and rapidity (y) differential production cross sections, mean transverse momentum and mean transverse momentum square of inclusive J/psi and psi(2S) at forward rapidity (2.5 < y < 4) as well as psi(2S)-to-J/psi cross section ratios. These quantities are measured in pp collisions at center of mass energiesv root s = 5.02 and 13 TeV with the ALICE detector. Both charmonium states are reconstructed in the dimuon decay channel, using the muon spectrometer. Acomprehensive comparison to inclusive charmonium cross sections measured at root s = 2.76, 7 and 8 TeV is performed. A comparison to non-relativistic quantum chromodynamics and fixed-order next-to-leading logarithm calculations, which describe prompt and non-prompt charmonium production respectively, is also presented. A good description of the data is obtained over the full p(T) range, provided that both contributions are summed. In particular, it is found that for p(T) > 15 GeV/c the non-prompt contribution reaches up to 50% of the total charmonium yield
Energy geostructures: a collection of data from real applications
No full textEnergy geostructures are geotechnical structures with the dual role of providing both the important role of structural stability whilst also acting as a heat exchanger with the ground, enabling the supported buildings and or infrastructure to be heated and cooled using the principle of low enthalpy geothermal systems. The main advantage of this innovative technology with respect to standard geothermal plant is the reduction of the initial installation costs and construction programme benefits, compared to installing conventional geothermal solutions, largely due to the supplementary use of structures which would be constructed in any case. However, it is important with respect to energy geostructures that additional aspects need to be carefully considered. For this very reason, several research studies have been carried out over the last decade on this subject and a number of real case studies have been monitored and analysed. The key difference with respect to conventional shallow geothermal systems are mainly due to the geometry, which is imposed by the geotechnical project, and the need for ensuring that the primary structural role is always guaranteed. Special boundary conditions, the reduced depth, the influence of atmospheric external temperature can play an important role for energy geostructures. They can affect, on the one hand, the energy efficiency and, on the other hand, the geotechnical behaviour because of the possible thermal induced mechanical effects. This paper collects available data to provide a reference framework and a picture of the current situation regarding energy geostructures and their peculiar features. Data has been collected from literature and personal communications and then processed to provide easy-to-read charts useful for practical consultation at a glance. This provides, among others, a figure of the distribution of such systems worldwide, their spread in time, and a global idea of their actual efficiency from the structural, energy, economic and environmental point of view
A Voronoi-based Algorithm for Hydraulic Fracturing Simulation in Deep Geothermal Wells
No full textPotential Hot Dry Rock (HDR) reservoirs underlie the entire world, and are characterized by hot rocks with insufficient or little natural permeability. To improve this aspect, Enhanced Geothermal Systems (EGS) are artificially created by injecting fluid into the subsurface. Fluid injection causes pre-existing fractures to re-open, thus creating permeability. This process is known as hydraulic fracturing. HDR field experiments are expensive to perform and cannot be repeated indefinitely from the same borehole due to progressive irreversible changes in the system under study. Numerical simulation provides a tool to demonstrate understanding of the available experimental results and to extend that understanding to other conditions. This leads to a predictive capability, lending support to design and operational planning. The modelling of a reservoir, including all interactions between fracture/channel flow paths and the host rock, is a challenging problem and has been dealt with in a number of studies. This paper extends and enhances a previous approach formulated by the Authors to simulate the hydraulic fracturing process and predict the fracture network between an injection and a production well. The Voronoi tessellation was used within the framework of the Distinct Element Method (DEM). To model fractures opening and propagation more realistically, an improved algorithm called HYDRA (HYDRofracking Algorithm) was implemented in the FISH programming language in application to the simple case study of a man-made geothermal field. HYDRA attempted to identify and discern shear and tensile fractures, neglecting those arising albeit not communicating with any well, and subsequently reproduced gradual fracture propagation, fluid inlet in fractures and pressure application on the fracture sides. At each stage, pressure inside fractures was the same as the one imposed over the wells boundary and was increased step by step when no more fractures developed. Based on the results of the computation, it was possible to capture the fracture pattern originated from the algorithm execution and the fluid pressure necessary to create a communicating channel through the wells
Dunes changing their shape The case of the dunes of the Laayoune Sakia El Hamra region
No full textSand can create an endlessly moving collection of dunes, drifted by the prevailing winds. However, it can happen that, changing the winds, also the motion and the shape of the dunes change. Here we show an example in the dunes of the Laayoune-Sakia El Hamra region, in the west of Sahara. We can observe that the barchans assume a deformed shape in the satellite images of 2016, images that we can find in the time series of Google Earth. The origin of this deformation is in the change of the prevailing wind
