1,721,105 research outputs found
A Support System to Manage Product and Process Changes in Manufacturing
No full textDifferent kinds of technological data are continuously generated in manufacturing enterprises, concerning the production of specific products. Especially in small enterprises, these data usually are not stored in a centralized knowledge management system. Thus, SMEs have difficulties in reusing the knowledge deriving from previous products when a new product has to be produced. Starting from the analysis of the technological data available in manufacturing enterprises, a model is designed to support the structuring of the manufacturing knowledge. It was also provided a classification of the possible changes in the manufacturing process that can be seen as variation to a previous product and thus can be managed more efficiently. In fact, changes in the components or in the production operations can be done more easily starting from the knowledge of a previous product instead of redoing from scratch. The usage of the proposed management system will allow a more easy evaluation of different product and process alternatives from the point of view of the final cost
Semantic organization of product lifecycle information through a modular ontology
No full textIt is known that one of the main reasons of the success of manufacturing enterprises is their ability to design and maintain a coherent structure to represent their knowledge, especially the small and medium sized enterprises (SMEs), which are not often organized to manage information efficiently. Several commercial PLM systems have been developed in the last years to help companies in organizing their large amount of data, but they are rarely exploited mainly due to the high cost and difficult customization. Recent trends in literature focused on the development of semantic knowledge management systems, both to help companies in organizing and sharing their data and to allow the easy finding of information and its reuse. The aim of this paper is to develop a knowledge management system to structure the product lifecycle knowledge of SMEs based on a modular ontology. The modular ontology contains a reference ontology to represent the main concepts with their relationships, and several domain-specific ontologies to specialize and enrich the reference ontology with specific information. Particularly, this paper is focused on the specification of the reference ontology with a manufacturing process ontology module. Some examples of the usage of the system to extract information through SPARQL queries are also presented. © 2015, North Atlantic University Union. All rights reserved
Measuring product semantic similarity by exploiting a manufacturing process ontology
No full textThe retrieval of manufacturing knowledge in companies is critical because product and process knowledge was not actually managed but only documented. Particularly, the identification of similarities between new and past products relied almost exclusively on the memory and the experience of people, and thus it is a time-consuming task. In this paper, a method to allow the automatic identification of past similar products is proposed, so that they can be used to speed up the design of manufacturing of the new product. The similarity is computed by using a semantic model in the form of ontology, which constitutes the hierarchical structure of concepts. A new similarity index is defined based on the portion of overlapping subgraph of concepts existing between two products. The different weight of each node is also considered because more descendants the node has, less specific its semantics information content is. The computation of the similarity measurement will allow the discovering of knowledge from stored data, thus supporting the engineers in searching for past products having similar characteristics with the new one. The potentiality of the proposed index is shown in a motivating exampl
Hydrological cycle during droughts: large-scale analyses for process understanding and modelling
No full textDroughts strongly affect the environment and human activities with long-term and
far-reaching impacts that will increase in the next decades under global changes.
Thus, we need an in-depth understanding of drought processes and their robust modelling
to cope with drought risk. For hydrologists, recurring challenges include predicting
the impacts of precipitation (P) deficits in the form of soil moisture, streamflow
(Q), or groundwater deficits. Water stored in catchments and evapotranspiration
(ET) regulate drought evolution, that is the propagation of P deficits through the hydrological
cycle and the subsequent recovery. Yet, analyses explicitly considering
the joint contribution of storage and ET to drought evolution across different hydroclimatic
regimes are rare. Furthermore, many hydrological models poorly simulate
Q during droughts, but previous studies have rarely assessed model performances
during droughts in multi-variable and spatially-distributed evaluations. This PhD
thesis aimed to answer two main research questions: (i) do storage changes and
ET affect drought evolution across climates and landscapes?; (ii) does a distributed
hydrological model properly represent Q, ET, and storage during droughts? I performed
a large-sample data-based analysis of Q, ET, and changes in the subsurface
storage (in soil and groundwater) over the period 2010-2019 for 102 Italian catchments
to answer the first question. To address the second question, I evaluated Q,
ET, and storage simulations from the process-based distributed hydrological model
Continuum over the Po river basin (northern Italy) during recent droughts, including
the severe 2022 event. From the large-sample data-based analysis, I found that
annual subsurface storage changes represented on average 11% of annual P across
the study catchments, and mostly buffered Q deficits during drought years and their
recovery. ET, instead, both buffered and aggravated Q deficits, and it had a decoupled
response to P. These results revealed the prominent role of subsurface storage
in driving the evolution of annual droughts. From model evaluation, I showed worse
model performances in simulating Q for severe than for moderate droughts (mean
KGE across the 38 study sub-catchments = 0.55±0.25 during moderate droughts and
0.18±0.69 in 2022) and I linked them to a degraded simulation of ET, rather than
storage, especially in the human-affected croplands (mean r = -0.03 and nRMSE
= 1.8 across the croplands in 2022). By calibrating the model during a moderate
drought, I showed similar model performances during the severe event (mean KGE =
0.18±0.63), which further point to specific human-water processes during this event.
Therefore, I delineated possible ways forward for model improvement during severe
droughts, such as an enhanced consideration of human interference, especially in ET.
The findings of the thesis provided a consistent picture of the different role ET and
storage have in drought evolution and in our modelling capabilities, coherently with
recent literature, also on multi-year droughts. Moreover, these results emphasized
the need for a holistic approach across the hydrological cycle for process understanding
and model evaluation during droughts, with the ultimate goal of improving
drought modelling for water resources management, disaster risk reduction, and climate
change impact assessments
Promoting SME cooperative aggregations: main criteria and contractual models
Full text linkCollaboration is considered an effective solution to improve business strategies. However, small and medium enterprises (SMEs) often lack common principles and common forms of contractual coordination. Several policies implemented by the EU have addressed the set-up of a comprehensive SME policy framework, but European institutions seem to have focused more on organisational devices to conduct business activities rather than on contractual forms of coordination. In April 2009, Italy adopted a law in network contract to promote the development of inter-firm cooperation strategies to foster enterprises' innovation and growth. Even if this law represents a novelty in Europe and may offer new challenges and hints, it still presents some lacks in its formulation. The current research aims at presenting the Italian law for network contract and a comparison with other models of SME aggregations adopted in EU countries. A formal model to support the design of an SME network was proposed, by providing both an ontology-based model to help the definition of the contract in a structured way, and a basic workflow to identify the important phases of the network design, i.e. the feasibility study and the negotiatio
Product Knowledge Management in Small Manufacturing Enterprises
No full textAn important issue present in the most of manufacturing systems, and become worse in SMEs, is the systematic management of the huge amount of unstructured information generated about products, from their design to their disposal. The aim of this chapter is to define a framework to manage such kind of data, overcoming the actual issues of the meaningless and the unstructured nature of generated information. To this aim, a knowledge management platform is proposed, both to store product information with semantic enrichment and to retrieve product information by means of a new similarity index. Such platform is based on the one hand on a non-relational data management system and on the other hand on a set of manufacturing ontologies. An example of the potentiality of the proposed framework is shown in the domain of telecommunication filter manufacturin
Multifunctional nanostructures for intracellular delivery and sensing in electrogenic cells
No full textBiological studies on in vitro cell cultures are of fundamental importance for investigating cell response to external stimuli, such drugs for specific treatments, or for studying communication between cells. In the electrophysiology field, multielectrode array devices (MEA) are the gold standard for the study of large ensambles of electrogenic cells. Thus, their improvement is a central topic nowadays in neuroscience and cardiology [1]. In the last decades, thanks to the adoption of nanotechnologies, the study of physiological and pathological conditions of electro-active cells in culture have becomes increasingly accurate[2], allowing for monitoring action potentials from many cells simultaneously.
In fact, nanoscale biomaterials were able to overcome the limitations of previous technologies, paving the way to the development of platforms for interfacing the electrogenic cells at unprecedented spatiotemporal scales. These devices, together with microfluidics, are starting to be used for drug screening and pharmaceutical drug development since they represent a powerful tool for monitoring cell response when cultures are stimulated by target compounds.
Many pharmaceutical agents, however, including various large molecules (enzymes, proteins, antibodies) and even drug-loaded pharmaceutical nanocarriers, need to be delivered intracellularly to exercise their therapeutic action inside the cytoplasm[3]. Nanoscale electrodes offer individual cell access and non-destructive poration of the cellular membrane enabling high capability in the delivery of biomolecules. Among all the techniques, electroporation have proven encouraging potential as alternative to the carrier mediated methods for molecular delivery into cultured cells[4].
In this regard, different groups [5][6][7] exploited the integration of nanostructures with delivering capabilities with single-cell specificity and high throughput in biosensing platforms. These efforts provided powerful tools for advancing applications in therapeutics, diagnostics, and drug discovery, in order to reach an efficient and localized delivery on a chip.
Despite these new tactics, there is still a critical need for the development of a functional approach that combines recording capabilities of nanostructured biosensors with intracellular delivery. The device should provide for tight contact between cells and electrode so as to enable highly localized delivery and optimal recording of action potentials in order to attain a high degree of prediction for the disease modeling and drug discovery. This “on-chip” approach will help to gain deeper insight in several bio-related studies and analyses, providing a comprehensive knowledge of the entire cellular dynamics when selectively stimulated by the desired bio-molecules.
In the first part of this dissertation, a solution will be proposed in order to fill this gap and respond to this need in the biology field.
In the first chapter, I will describe briefly the principles of action potentials and how neurons and cardiomyocyte are composed, together with the development of electrophysiology and the advent of multielectrode arrays.
In the second chapter, more details about fabrication and cell-electrode system modelling will be explained. In the same chapter, I will explore the development of multielectrode arrays up to the present days, along with the advent of nanotechnologies and the related techniques for improving the previous platforms. The different cell poration techniques will be described in order to reach the best recording capabilities without damaging cells. Electroporation, optoporation and spontaneous poration will be presented and the chosen technique for our application (electroporation) will be reviewed more in detail.
In the third chapter, different methodologies for intracellular delivery will be explained, focusing also on the electroporation technique. A small paragraph about the integration of these techniques on chip will be inserted to illustrate the state of the art of these devices.
The fourth chapter will explicate in details the Microfluidic multielectrode array idea, the approach used in order to fabricate this novel platform from scratch, the experiments carried out to verify its capabilities and the associated results.
In the last paragraph, I will discuss how the proposed platform could became suitable for the day to day uses in research activity by employing nanoporous materials.
In fact, big efforts are carried out in order to find appropriate metamaterials as substitutes of the 3D counterparts so as to decrease the cost of device manufacturing that makes them unfitting with research activity.
As a novel electrode material, nanoporous metals possess unique properties, such as a low fabrication cost, high plasmonic enhancement and large surface-volume ratio[8].
Nanoporous gold behaves like a metamaterial whose effective dielectric response can be tuned accordingly to the wanted use. These properties make the material suitable for multiple biosensing application, from a high-performance and reliable SERS (surface enhanced raman scattering) substrate [9] to an electrode in CMOS MEAs capable of intracellular recordings[10].
All these properties were explored in the last years, but it could be interesting to further study if the characteristics of this material could make it a good photoelectrical modulating material for eliciting electrogenic cells firing activity. In this way, this technology could be in principle easily implemented on commercial CMOS devices, consenting stimulation and recording at single cell level with high-resolution sensors, opening the way to new methodologies for studying electrogenic cells and tissues.
Electrical stimulation of excitable cells is the basis for many implantable devices in cardiac treatment and in neurological studies for treating debilitating neurological syndromes. In order to make the technique less invasive, optical stimulation was widely investigated [11]. The non-genetic photostimulation is starting to make its way in the field since it allows to avoid changing the biological framework by using transient thermal or electrochemical outputs from synthetic materials attached to the target cells[12]. If stimulated with impinging light these materials could inject free charges into the solution resulting in an ionic current at the interface able to eliciting of neurons[13] or cardiomyocyte action potentials.
Plasmonic porous materials have all the suitable properties to be considered as an appealing tools for charge injection and consequently for stimulation of electrically active cells [14].
Thus, the second part of this dissertation will exploit the capabilities of these plasmonic metamaterials, placing particular emphasis on the possibility of photoelectrochemical modulation.
In particular, in the fifth and last chapter I will describe all the properties and application of the porous material and the mechanism of photoemission.
In the experimental paragraphs, the free charge photoemission properties of porous gold will be explored together with plasmonic non-genetic photostimulation of the cardiac cells on commercial CMOS MEAs
Gestire i dati del Parco Naturale Alpi Marittime: una proposta di organizzazione con software open source
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