3,073 research outputs found
A Systematic Approach for Evaluating Satellite Communications Systems
The aerospace environment imposes straight opera- tive conditions so every electronic system usually needs to be validated for these. The same way, communica- tion systems need to be evaluated before their intro- duction in aerospace applications. In the paper we present a new methodology for the evaluation of com- munication systems in space applications. The meth- odology aims, by abstraction, at identifying all the critical aspects for the evaluation and at defining a standard and reusable framework in order to be appli- cable to any Communication Systems. The methodol- ogy has been applied for the evaluation of three Data Bus for satellite communications: 1553, 1-Wire and Profibus DP RS 485 based systems have been analyzed and evaluate
DoE Method for Operating Parameter Optimization of a Dual-Fuel BioEthanol/Diesel Light Duty Engine
In recent years, alcoholic fuels have been considered as an alternative transportation biofuel even in compression ignition engines either as blended in diesel or as premixed fuel in the case of dual-fuel configuration. Within this framework, the authors investigated the possibility to improve the combustion efficiency when ethanol is used in a dual-fuel light duty diesel engine. In particular, the study was focused on reducing the HC and CO emissions at low load conditions, acting on the most influential engine calibration parameters. Since this kind of investigation would require a significant number of runs, the statistical design of experiment methodology was adopted to reduce significantly its number. As required by the DoE approach, a set of factors (injection parameters, etc.) were selected. For each of them, two levels "high" and "low" were defined in a range of reasonable values. Combining the levels of all the factors, it was possible to evaluate the effects and the weight of each factor and of their combination on the outputs. The results identified the rail pressure, the pilot, and post-injection as the most influential emission parameters. Significant reductions of unburnt were found acting on those parameters without substantial penalties on the global engine performances
Autoimmune diseases and their manifestations on oral cavity: diagnosis and clinical management
Oral signs are frequently the first manifestation of autoimmune diseases. For this reason, dentists play an important role in the detection of emerging autoimmune pathologies. Indeed, an early diagnosis can play a decisive role in improving the quality of treatment strategies as well as quality of life. This can be obtained thanks to specific knowledge of oral manifestations of autoimmune diseases. This review is aimed at describing oral presentations, diagnosis, and treatment strategies for systemic lupus erythematosus, Sjögren syndrome, pemphigus vulgaris, mucous membrane pemphigoid, and Behcet disease
An area-efficient 2-D convolution implementation on FPGA for space applications
The 2-D Convolution is an algorithm widely used in image and video processing. Although its computation is simple, its implementation requires a high computational power and an intensive use of memory. Field Programmable Gate Arrays (FPGA) architectures were proposed to accelerate calculations of 2-D Convolution and the use of buffers implemented on FPGAs are used to avoid direct memory access. In this paper we present an implementation of the 2-D Convolution algorithm on a FPGA architecture designed to support this operation in space applications. This proposed solution dramatically decreases the area needed keeping good performance, making it appropriate for embedded systems in critical space application
The gravitational eikonal: from particle, string and brane collisions to black-hole encounters
Motivated by conceptual problems in quantum theories of gravity, the
gravitational eikonal approach, inspired by its electromagnetic predecessor,
has been successfully applied to the transplanckian energy collisions of
elementary particles and strings since the late eighties, and to string-brane
collisions in the past decade. After the direct detection of gravitational
waves from black-hole mergers, most of the attention has shifted towards
adapting these methods to the physics of black-hole encounters. For such
systems, the eikonal exponentiation provides an amplitude-based approach to
calculate classical gravitational observables, thus complementing more
traditional analytic methods such as the Post-Newtonian expansion, the
worldline formalism, or the Effective-One-Body approach. In this review we
summarize the main ideas and techniques behind the gravitational eikonal
formalism. We discuss how it can be applied in various different physical
setups involving particles, strings and branes and then we mainly concentrate
on the most recent developments, focusing on massive scalars minimally coupled
to gravity, for which we aim at being as self-contained and comprehensive as
possible.Comment: 208 pages, 19 figure
The eikonal operator at arbitrary velocities I: the soft-radiation limit
Observables related to the real part of the gravitational eikonal, such as
the deflection angle and time delay, have been found so far to have a smooth
post-Minkowskian (PM) expansion whose validity extends from the
non-relativistic to the most extreme ultra-relativistic (UR) regime, which
smoothly connects with massless particle collisions. To describe gravitational
radiation, the eikonal phase has to be promoted to a unitary operator for which
we motivate a proposal and start discussing properties in the soft-radiation
limit. A convergent PM expansion is found to only hold below an UR bound
(discussed in the GR literature in the seventies) above which a different
expansion is instead needed implying, in general, some non-analyticity in
Newton's constant. In this extreme UR regime soft radiative observables receive
contributions only from gravitons and are therefore universal. This generalises
the pattern discussed in \cite{DiVecchia:2020ymx} beyond the elastic case.Comment: 28 pages+reference
Gender assessment through three-dimensional analysis of maxillary sinuses by means of Cone Beam Computed Tomography
OBJECTIVE:
The availability of a low dose radiation technology such as Cone Beam Computed Tomography (CBCT) in dental practice has increased the number of scans available for forensic purposes. Moreover, specific software allows for three-dimensional (3D) characterization of the maxillary sinuses. This study was performed to determine whether sinus maxillary volumes can be useful to identify gender after validating the use of the Dolphin software as a tool for volumetric estimation of maxillary sinus volumes.
PATIENTS AND METHODS:
The validation was performed by four different operators measuring the volume of six phantoms, where the real volume was already known. The maxillary sinus volumes of 52 patients (26 males and 26 females) mean age 24.3 were calculated and compared between genders and sagittal skeletal class subdivision. The measurements for patients and phantoms were based on CBCT scans (ILUMA™) processed by Dolphin 3D software.
RESULTS:
No statistical difference was observed between the real volume and the volume measurements performed by the operators. No statistical difference was found in patient's maxillary sinus volumes between gender.
CONCLUSIONS:
Based on our results, it is not possible to support the use of maxillary sinuses to discern sexual difference in corpse identification
Involvement of Astrocytes in the Formation, Maintenance, and Function of the Blood-Brain Barrier
: The blood-brain barrier (BBB) is a fundamental structure that protects the composition of the brain by determining which ions, metabolites, and nutrients are allowed to enter the brain from the blood or to leave it towards the circulation. The BBB is structurally composed of a layer of brain capillary endothelial cells (BCECs) bound to each other through tight junctions (TJs). However, its development as well as maintenance and properties are controlled by the other brain cells that contact the BCECs: pericytes, glial cells, and even neurons themselves. Astrocytes seem, in particular, to have a very important role in determining and controlling most properties of the BBB. Here, we will focus on these latter cells, since the comprehension of their roles in brain physiology has been continuously expanding, even including the ability to participate in neurotransmission and in complex functions such as learning and memory. Accordingly, pathological conditions that alter astrocytic functions can alter the BBB's integrity, thus compromising many brain activities. In this review, we will also refer to different kinds of in vitro BBB models used to study the BBB's properties, evidencing its modifications under pathological conditions
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