302 research outputs found
A Software-defined SoC Memory Bus Bridge Architecture for Disaggregated Computing
Disaggregation and rack-scale systems have the potential of drastically
decreasing TCO and increasing utilization of cloud datacenters, while
maintaining performance. While the concept of organising resources in separate
pools and interconnecting them together on demand is straightforward, its
materialisation can be radically different in terms of performance and scale
potential.
In this paper, we present a memory bus bridge architecture which enables
communication between 100s of masters and slaves in todays complex
multiprocessor SoCs, that are physically intregrated in different chips and
even different mainboards. The bridge tightly couples serial transceivers and a
circuit network for chip-to-chip transfers. A key property of the proposed
bridge architecture is that it is software-defined and thus can be configured
at runtime, via a software control plane, to prepare and steer memory access
transactions to remote slaves. This is particularly important because it
enables datacenter orchestration tools to manage the disaggregated resource
allocation. Moreover, we evaluate a bridge prototype we have build for ARM AXI4
memory bus interconnect and we discuss application-level observed performance.Comment: 3rd International Workshop on Advanced Interconnect Solutions and
Technologies for Emerging Computing Systems (AISTECS 2018, part of HiPEAC
2018
Quality of Service in Distributed Stream Processing for large scale Smart Pervasive Environments
The wide diffusion of cheap, small, and portable sensors integrated in an unprecedented large variety of devices and the availability of almost ubiquitous Internet connectivity make it possible to collect an unprecedented amount of real time information about the environment we live in. These data streams, if properly and timely analyzed, can be exploited to build new intelligent and pervasive services that have the potential of improving people's quality of life in a variety of cross concerning domains such as entertainment, health-care, or energy management. The large heterogeneity of application domains, however, calls for a middleware-level infrastructure that can effectively support their different quality requirements.
In this thesis we study the challenges related to the provisioning of differentiated quality-of-service (QoS) during the processing of data streams produced in pervasive environments. We analyze the trade-offs between guaranteed quality, cost, and scalability in streams distribution and processing by surveying existing state-of-the-art solutions and identifying and exploring their weaknesses. We propose an original model for QoS-centric distributed stream processing in data centers and we present Quasit, its prototype implementation offering a scalable and extensible platform that can be used by researchers to implement and validate novel QoS-enforcement mechanisms. To support our study, we also explore an original class of weaker quality guarantees that can reduce costs when application semantics do not require strict quality enforcement. We validate the effectiveness of this idea in a practical use-case scenario that investigates partial fault-tolerance policies in stream processing by performing a large experimental study on the prototype of our novel LAAR dynamic replication technique.
Our modeling, prototyping, and experimental work demonstrates that, by providing data distribution and processing middleware with application-level knowledge of the different quality requirements associated to different pervasive data flows, it is possible to improve system scalability while reducing costs
Mass accretion to young stars triggered by flaring activity in circumstellar disks
Young low-mass stars are characterized by ejection of collimated outflows and
by circumstellar disks which they interact with through accretion of mass. The
accretion builds up the star to its final mass and is also believed to power
the mass outflows, which may in turn remove the excess angular momentum from
the star-disk system. However, although the process of mass accretion is a
critical aspect of star formation, some of its mechanisms are still to be fully
understood. A point not considered to date and relevant for the accretion
process is the evidence of very energetic and frequent flaring events in these
stars. Flares may easily perturb the stability of the disks, thus influencing
the transport of mass and angular momentum. Here we report on three-dimensional
magnetohydrodynamic modeling of the evolution of a flare with an idealized
non--equilibrium initial condition occurring near the disk around a rotating
magnetized star. The model takes into account the stellar magnetic field, the
gravitational force, the viscosity of the disk, the magnetic-field-oriented
thermal conduction (including the effects of heat flux saturation), the
radiative losses from optically thin plasma, and the coronal heating. We show
that, during its first stage of evolution, the flare gives rise to a hot
magnetic loop linking the disk to the star. The disk is strongly perturbed by
the flare: disk material evaporates under the effect of the thermal conduction
and an overpressure wave propagates through the disk. When the overpressure
reaches the opposite side of the disk, a funnel flow starts to develop there,
accreting substantial disk material onto the young star from the side of the
disk opposite to the flare.Comment: 14 pages, 10 Figures; accepted for publication on MNRAS. Version with
full resolution images can be found at
http://www.astropa.unipa.it/~orlando/PREPRINTS/sorlando_mnras.pd
The Molecular Weight Dependence of Thermoelectric Properties of Poly (3-Hexylthiophene)
Organic materials have been found to be promising candidates for low-temperature thermoelectric applications. In particular, poly (3-hexylthiophene) (P3HT) has been attracting great interest due to its desirable intrinsic properties, such as excellent solution processability, chemical and thermal stability, and high field-effect mobility. However, its poor electrical conductivity has limited its application as a thermoelectric material. It is therefore important to improve the electrical conductivity of P3HT layers. In this work, we studied how molecular weight (MW) influences the thermoelectric properties of P3HT films. The films were doped with lithium bis(trifluoromethane sulfonyl) imide salt (LiTFSI) and 4-tert butylpyridine (TBP). Various P3HT layers with different MWs ranging from 21 to 94 kDa were investigated. UV–Vis spectroscopy and atomic force microscopy (AFM) analysis were performed to investigate the morphology and structure features of thin films with different MWs. The electrical conductivity initially increased when the MW increased and then decreased at the highest MW, whereas the Seebeck coefficient had a trend of reducing as the MW grew. The maximum thermoelectric power factor (1.87 μW/mK2) was obtained for MW of 77 kDa at 333 K. At this temperature, the electrical conductivity and Seebeck coefficient of this MW were 65.5 S/m and 169 μV/K, respectively
airbrush spray coating of amorphous titanium dioxide for inverted polymer solar cells
One of the main topics of organic photovoltaics manufacturing is the need for simple, low cost, and large area compatible techniques. Solution-based processes are the best candidates to achieve this aim. Among these, airbrush spray coating has successfully applied to deposit both active and PEDOT layers of bulk-heterojunction solar cells. However, this technique is not yet sufficiently studied for interfacial layers (electron and hole transporting layers or optical spacers). In this paper, we show that amorphous titanium dioxide ( ) films, obtained with an airbrush from a solution of titanium (IV) isopropoxide diluted in isopropanol, are successfully deposited on glass and PET substrates. Good surface covering results from the coalescence of droplets after optimizing the spray coating system. Simple inverted polymer solar cells are fabricated using as electron transporting layer obtaining encouraging electrical performances ( % on glass/FTO and 0.7% on PET/ITO substrates)
Il lavoro agile negli enti pubblici di ricerca
Working Paper Ircres-CNR 01/2020. This paper presents a first result of an IRCrES research project on the effects of smart working in public research organizations. The study aims at understanding the value of autonomous organization of individual work relatively to the production of new scientific knowledge in public research institutions (OECD, 2011), with a focus on the forms of smart working implemented in public research institutions also with reference to the social containment measures deriving from the pandemic due to COVID-19. The organizations examined in this first phase are the National Institute of Astrophysics (INAF), the National Institute of Nuclear Physics (INFN) and the National Institute of Geophysics and Volcanology (INGV), which have introduced regulations of smart working before the pandemic emergency. In addition to these, the National Research Council (CNR) which had not yet activated smart working at the time of the emergency due to COVID-19 pandemic, and had to face problems connected to its regulation. For each of these organizations, authors analyze the implementation of smart working through rules and regulations
Cloning and expression analysis of a Petunia hybrida flower specific mitotic-like cyclin
AbstractA cyclin cDNA clone (Pethy;CycB1;1) was isolated from a Petunia hybrida ovary specific cDNA library. Sequence comparison revealed that Pethy;CYCB1;1 protein is highly homologous to mitotic B1 cyclins. Northern analysis and in situ hybridisation experiments showed that its expression is developmentally regulated and restricted to flower organs. We have attempted to define some of the cell division patterns which contribute to shaping each floral organ by analysing Pethy;CycB1;1 expression on Petunia flower sections. While in sepals, epidermis and parenchyma cell division patterns were comparable, there were two distinct cell division patterns in petals. In the epidermis, Pethy;CYCB1;1 expression was found both at the petal tip and along epidermis, whereas in the parenchyma only at the petal tips. In reproductive organs cell divisions were detected only in sporophytic tissues. No signals were detected inside meiotic cells
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