692 research outputs found
Near-ideal spontaneous photon sources in silicon quantum photonics
While integrated photonics is a robust platform for quantum information
processing, architectures for photonic quantum computing place stringent
demands on high quality information carriers. Sources of single photons that
are highly indistinguishable and pure, that are either near-deterministic or
heralded with high efficiency, and that are suitable for mass-manufacture, have
been elusive. Here, we demonstrate on-chip photon sources that simultaneously
meet each of these requirements. Our photon sources are fabricated in silicon
using mature processes, and exploit a novel dual-mode pump-delayed excitation
scheme to engineer the emission of spectrally pure photon pairs through
intermodal spontaneous four-wave mixing in low-loss spiralled multi-mode
waveguides. We simultaneously measure a spectral purity of ,
a mutual indistinguishably of , and intrinsic
heralding efficiency. We measure on-chip quantum interference with a visibility
of between heralded photons from different sources. These
results represent a decisive step for scaling quantum information processing in
integrated photonics
Development of a 2-Stroke GDI Engine
Nowadays, high-pressure gasoline direct injection (GDI) can be considered a standard technology, due to the wide application on 4-stroke turbocharged engines. This technology - in combination with other specific solutions - has been successfully applied to a 500 cc, 30 kW 2-stroke engine, initially developed as a range extender. The engine is valve-less and cam-less, being the scavenge and exhaust ports controlled by the piston. An electric supercharger delivers the required airflow rate, without need of a throttle valve; the lubrication is identical to a 4-stroke. The current study reviews the development process, assisted by CFD simulation, that has brought to the construction of a prototype, tested at the dynamometer bed of the University of Modena and Reggio Emilia (Engineering Department "Enzo Ferrari"). An experimentally calibrated CFD-1d model is applied to predict full load engine performance. The results show an excellent fuel efficiency and a very low level of thermal and mechanical stress despite the high power density
Personalized medicine—a modern approach for the diagnosis and management of hypertension
The main goal of treating hypertension is to reduce blood pressure to physiological levels and thereby prevent risk of cardiovascular disease and hypertension-associated target organ damage. Despite reductions in major risk factors and the availability of a plethora of effective antihypertensive drugs, the control of blood pressure to target values is still poor due to multiple factors including apparent drug resistance and lack of adherence. An explanation for this problem is related to the current reductionist and ‘trial-and-error’ approach in the management of hypertension, as we may oversimplify the complex nature of the disease and not pay enough attention to the heterogeneity of the pathophysiology and clinical presentation of the disorder. Taking into account specific risk factors, genetic phenotype, pharmacokinetic characteristics, and other particular features unique to each patient, would allow a personalized approach to managing the disease. Personalized medicine therefore represents the tailoring of medical approach and treatment to the individual characteristics of each patient and is expected to become the paradigm of future healthcare. The advancement of systems biology research and the rapid development of high-throughput technologies, as well as the characterization of different –omics, have contributed to a shift in modern biological and medical research from traditional hypothesis-driven designs toward data-driven studies and have facilitated the evolution of personalized or precision medicine for chronic diseases such as hypertension
Energy Savings in the Hydraulic Circuit of Agricultural Tractors
Increasing interest in reducing pollutant emissions and fuel consumption of off-road vehicles has led to research into alternative systems that aim to reduce the power dissipation of the hydraulic circuits equipping such vehicles. This work proposes alternative hydraulic architectures for agricultural tractors in comparison with traditional systems. The alternative circuit architecture uses independent metering valves and electronically controlled variable pump and involves different control strategies. The analysis is performed with reference to the hydraulic circuit and operating conditions of the remote utilities of a medium-sized tractor. A duty cycle for remote utilities is used for the analysis, obtained from experimental measurements on a tractor equipped with a front loader. Traditional and alternative architectures are modelled using a lumped parameter approach. In this way it is demonstrated that considerable energy savings can be achieved using the alternative architectures
Pressure Losses in Multiple-Elbow Paths and in V-Bends of Hydraulic Manifolds
Hydraulic manifolds are used to realize compact circuit layouts, but may introduce high pressure losses in the system because their design is usually oriented to achieving minimum size and weight more than reducing the pressure losses. The purpose of this work is to obtain the pressure losses when the internal connections within the manifold are creating complex paths for the fluid and the total loss cannot be calculated simply as the sum of the single losses. To perform the analysis both Computational Fluid Dynamic (CFD) analysis and experimental tests have been executed. After the comparison between numerical and experimental results, it was possible to assess that the numerical analysis developed in this work is able to depict the correct trends of the pressure losses also when complex fluid path are realized in the manifold. Successively, the numerical analysis was used to calculate the pressure loss for inclined connections of channels (or V-bends), a solution that is sometimes adopted in manifolds to meet the design requirements aimed towards the minimum room-minimum weight objective
PRECISE Photonic hybRid EleCtromagnetic SolvEr
The Photonic hybRid EleCtromagnetic SolvEr (PRECISE) is a Matlab based
library to model large and complex photonics integrated circuits. Each circuit
is modularly described in terms of waveguide segments connected through
multiport nodes. Linear, nonlinear, and dynamical phenomena are simulated by
solving the system of differential equations describing the effect to be
considered. By exploiting the steady state approximation of the electromagnetic
field within each node device, the library can handle large and complex
circuits even on desktop PC. We show that the steady state assumption is
fulfilled in a broad number of applications and we compare its accuracy with
analytical model (coupled mode theory) and experimental results. PRECISE is
highly modular and easily extensible to handle equations different from those
already implemented and is, thus, a flexible tool to model the increasingly
complex photonic circuits.Comment: 21 pages, 13 figure
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