The financial support from Innovate UK, Ultra-light Car Bodies (UlCab, reference 101568) and Make it lighter, with less (LightBlank, reference 131818) are gratefully acknowledged. The research leading to these results has received funding from the European Union's Seventh Framework Program (FP7/2007-2013) under grant agreement No. 604240, project title 'An industrial system enabling the use of a patented, lab-proven materials processing technology for Low Cost forming of Lightweight structures for transportation industries (LoCoLite)'. Significant support was also received from the AVIC Centre for Structural Design and Manufacture at Imperial College London, which is funded by Aviation Industry Corporation of China (AVIC).

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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+on+hot+stamping.">A review on hot stamping.</a> J. Mater. Process. Tech. 210 (15), 2103-2118 (2010).</li><li>El Fakir, O., Wang, L., Balint, D., Dear, J. 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The authors have nothing to disclose.

La tecnica di simulazione KBC-FE permette simulazioni avanzate per essere condotte fuori del sito utilizzando i moduli dedicati. E &#39;possibile eseguire moduli funzionali in un ambiente cloud, che collegano i nodi da diverse specializzazioni, per garantire che le simulazioni di processo sono condotte nel modo più accurato possibile. Gli aspetti critici nella simulazione KBC-FE possono comportare indipendenza dei codici FE, efficienza del calcolo, e l&#39;accuratezza dei moduli funzionali. La realizzazione di ogni funzione avanzata in un modulo potrebbe basarsi sullo sviluppo di un nuovo modello e / o una nuova tecnica sperimentale. Ad esempio, il modulo limite formando è sviluppato sulla base del nuovo unificato limite formando la previsione del modello 11, e il modulo di predizione durata degli utensili di attrito è stato attualmente sviluppato dalla implementazione del modello di attrito interattivo 20. La tecnica di simulazione KBC-FE offre anche la funzione di computazione selettiva, cioè solo gli elementi che soddisfano la selezionecriteri sono selezionati per ulteriore valutazione nei singoli moduli. Per esempio, il modulo utensile vita previsione seleziona automaticamente gli elementi per i quali il rivestimento duro tende a ripartizione, classificando il tasso di usura di tutti gli elementi del primo formando ciclo, quindi di norma meno dell&#39;1% degli elementi saranno selezionati per ulteriore valutazioni durata dell&#39;utensile in condizioni di carico multi-ciclo. Nella presente ricerca, la previsione durata dell&#39;utensile dopo 300 cicli di formatura può essere completato entro 5 min. Conducendo le prove pertinenti e calibrare di conseguenza, il modello di limite di formatura può essere applicato a formare simulazioni di processo per determinare di conseguenza i parametri ottimali per la produzione di un componente da tali leghe successo, e senza incidenza di strizione. Il modello di predizione limite formando stato sviluppato come modulo nuvola che era indipendente dal software FE essere utilizzato, e può essere applicato a qualsiasi software FE per valutare la formabilità di un materiale duranteformando, senza subroutine complicati 17. Importando i dati rilevanti nel modello, i calcoli possono essere effettuati per determinare se si sarebbe verificato il fallimento, nelle regioni del componente che l&#39;utente potrebbe specificare, risparmio di risorse computazionali. Tuttavia, va notato che le curve sforzo-deformazione sono immessi nel software FE mediante una semplice tabella di look-up, può essere difficile per rappresentare appieno le proprietà del materiale a varie temperature e velocità di deformazione durante la simulazione. Nel modulo di predizione durata dell&#39;utensile, il comportamento di attrito durante la formatura può essere previsto importando i dati della cronologia deformazione richiesti nel modulo di attrito verificato 20, e quindi importando i punti dati discreti calcolati dal modulo cloud per ogni elemento nuovo nel software FE. Questo assicura che il modulo di attrito advanced può essere utilizzato da tutti i codici FE, indipendentemente dalla loro capacità di incorporare user-subroutines. Inoltre, il module potrebbe essere eseguito in parallelo per ridurre ulteriormente i tempi di calcolo. Il modello di attrito / usura interattivo assume l&#39;assenza di particelle di usura durante iniziale scorrimento, e di conseguenza, sarebbe ragionevole aspettarsi un valore iniziale del coefficiente di attrito costante 0,17 20. Anche se questo modello ha rivelato l&#39;evoluzione della distribuzione attrito, il comportamento di attrito durante un processo di formatura è molto complicato, ed è difficile integrare completamente il comportamento attrito complesso dal modulo nuvola nella simulazione FE. Come tecnologia del futuro, la simulazione KBC-FE si baserà sullo sviluppo di pacchetti software di simulazione FE basati su Internet dedicato e robusto, che richiederebbe un modello di business molto redditizio, ma completamente diverso da stabilirsi da parte degli sviluppatori di software. Inoltre, una rete interna dedicata deve essere costruita all&#39;interno delle parti di collaborazione per garantire la sicurezza dei dati e l&#39;affidabilità del controllo del sistema industriale. </p&gt;

Finite Element (FE) simulations have become a powerful tool for optimizing process parameters in the metal forming industry. The reliability of FE simulation results is dependent on the accuracy of the material definition, input in the form of flow stress data or constitutive equations, and the assignment of the boundary conditions, such as the friction coefficient and the heat transfer coefficient. In the past few years, advanced FE simulations have been developed via the implementation of user-defined subroutines, which have significantly broadened the capability of FE software.
The use of such advanced FE simulations in the design of forming processes for structural components has been investigated by both the aviation and automotive industries, with the intention of producing lightweight structures that reduces operating costs and CO2 emissions. Particular focus has been placed on the replacement of steel components with lower density materials, such as aluminum alloys and magnesium alloys. However, these alloys, especially the stronger variants, offer limited formability at room temperature and thus complex-shaped components cannot be manufactured using the conventional cold stamping process. Therefore, advanced high temperature forming technologies, such as warm aluminum forming 1-4, hot stamping of aluminum alloys 5-9 and hot stamping of high strength steels 10, have been developed over the past decades to enable complex-shaped components to be formed. In general, high temperature forming processes involve significant temperature variations, strain rate and loading path changes 11, which would, for instance, cause inevitable viscoplastic and loading history dependent responses from the work piece materials. These are intrinsic features of high temperature forming processes and may be difficult to represent using conventional FE simulation techniques. Another desirable feature would be the ability to predict the tool life over multiple forming cycles in such processes, since they require low friction characteristics achieved through coatings that degrade with each forming operation. To represent all these features via the implementation of user-defined subroutines would be computationally very expensive. Moreover, the development and implementation of multiple subroutines would require excessive multi-disciplinary knowledge from an engineer conducting the simulations.
In the present work, a novel Knowledge Based Cloud FE (KBC-FE) simulation technique is proposed, based on the application of modules on a cloud computing environment, that enables an efficient and effective method of modeling advanced forming features in conjunction with conventional FE simulations. In this technique, data from the FE software is processed at each cloud module, and then imported back into the FE software in the relevant consistent format, for further processing and analysis. The development of these modules and their implementation in the KBC-FE is detailed.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>AA6082-T6</td>
			<td>AMAG</td>
			<td></td>
			<td>Material</td>
		</tr>
		<tr>
			<td>AA5754-H111</td>
			<td>AMAG</td>
			<td></td>
			<td>Material</td>
		</tr>
		<tr>
			<td>&#160;1000 kN high-speed press</td>
			<td>ESH</td>
			<td></td>
			<td>Forming press</td>
		</tr>
		<tr>
			<td>ARGUS</td>
			<td>GOM</td>
			<td></td>
			<td>Optical forming analysis</td>
		</tr>
		<tr>
			<td>PAM-STAMP 2015</td>
			<td>ESI</td>
			<td></td>
			<td>FE simulation software</td>
		</tr>
		<tr>
			<td>Matlab&#160;</td>
			<td>MathWorks</td>
			<td></td>
			<td>Numerical calculation software</td>
		</tr>
		<tr>
			<td>Gleeble 3800</td>
			<td>DSI</td>
			<td></td>
			<td>Uniaxial tensile test</td>
		</tr>
		<tr>
			<td>High Temperature Tribometer (THT)</td>
			<td>Anton Paar</td>
			<td></td>
			<td>Friction property test</td>
		</tr>
		<tr>
			<td>NewViewTM 7100</td>
			<td>ZYGO</td>
			<td></td>
			<td>Surface profilometer</td>
		</tr>
		<tr>
			<td>&#160;Magnetron sputtering equipment</td>
			<td></td>
			<td></td>
			<td>Coating deposition</td>
		</tr>
		<tr>
			<td>Microhardness tester</td>
			<td>Wolpert Wilson Instruments</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nano-hardness indenter&#160;</td>
			<td>MTS</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

knowledge based cloud fe simulation of sheet metal forming processes

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques.
This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a material's forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions.

KBC-FE simulazione per Necking previsione In un processo di stampaggio a caldo, l&#39;uso di uno sbozzato di forma ottimizzata non solo di risparmiare il costo materiale ma anche contribuire a ridurre la presenza di difetti quali strizione, cracking, e rughe. La forma del pezzo grezzo iniziale influisce sul flusso di materiale notevolmente durante la formatura, e quindi un disegno sensibile della forma del pezzo grezzo è fondamentale per il successo del processo di stampaggio a caldo e la qualità dei prodotti finali. Per ridurre gli sforzi di esperimenti per tentativi ed errori per determinare la geometria vuoto ottimale, la simulazione KBC-FE è stato dimostrato di essere un metodo altamente efficiente ed efficace per ridurre al minimo le zone con collarino. Utilizzando questa tecnica, ogni simulazione richiede circa 2 ore, mentre il parallelo di calcolo del modulo di cloud per la previsione necking è completata entro 4 ore. Figura 4 mostra l&#39;evoluzione della forma del pezzo grezzo utilizzato nella stampa a caldo, un esempio di componente interno porta automobilistico. La forma vuoto iniziale, adottata da un processo di stampaggio a freddo convenzionale, è stata la prima nella simulazione KBC-FE. I risultati sperimentali in figura 4 (a), mostrano che gran fallimento (incrinatura o collarino) aree sono visibili dopo la stampa a caldo. Dopo una iterazione dell&#39;ottimizzazione forma del pezzo grezzo, che può essere visto in Figura 4 (b) che un gruppo quasi completamente successo è formata con molto meno necking, rispetto all&#39;utilizzo forma vuoto iniziale. Si può notare che c&#39;è ancora un&#39;indicazione necking at tasche in alto a destra e sinistra angoli del pannello. Dopo ulteriore ottimizzazione nella figura 4 (c), la forma del pezzo grezzo ottimizzato è stato finalmente ottenuto senza necking visibile sul pannello. La forma vuoto ottimizzata determinata dalla simulazione KBC-FE è stato verificato sperimentalmente attraverso la stampa a caldoprove condotte su una linea di produzione completamente automatizzata offerta da un produttore del sistema produttivo. KBC-FE simulazione per la vita Strumento previsione Convenzionali simulazioni FE di processi di formatura di metallo vengono eseguiti per un singolo ciclo. Tuttavia, in un ambiente di produzione, più cicli di formatura vengono eseguite su un determinato strumento, dove si è constatato che un aumento del numero di cicli di formatura comporta una maggiore differenza tra i componenti formati. Questa variazione durante multi-ciclo attrezzo caricatore è il risultato della modifica topografia superficiale. Ad esempio, il carico multi-ciclo di utensili con rivestimenti funzionali formando porterà ad una riduzione dello spessore del rivestimento a causa dell&#39;usura. Inoltre, la composizione del rivestimento sarà influenzato anche formando parametri, quali il carico / pressione, formando velocità, etc. La tecnica KBC-FE consentesimulazione del foglio processi di formatura in condizioni di carico a cicli multipli di metallo, che è essenziale per l&#39;in-service life previsione di utensili con rivestimenti funzionali avanzati formatura. Per studiare gli effetti della forza di tenuta vuoto sulla durata dell&#39;utensile, i valori di forza che tiene in bianco di 5, 20, e 50 kN sono stati esaminati per una velocità la formazione costante di 250 mm / s. La Figura 5 mostra la distribuzione dello spessore del rivestimento strumento restante con diverse forze azienda vuoto dopo 300 cicli di formatura. Essa indica chiaramente che lo spessore del rivestimento rimanente diminuisce con un aumento della forza di presa vuoto. La figura 6 mostra la distribuzione di spessore pressione e rivestimento rimanente con forze azienda vuoto di 5, 20, e 50 kN rispettivamente, lungo la distanza curvilinea dello stampo dopo 300 cicli di formatura. Dal momento che la regione AB rappresenta il ent stamporegione rance durante il processo di piegatura ad U, la pressione e la distanza relativa usura in questa regione molto superiori rispetto ad altre regioni dello stampo. Di conseguenza, l&#39;usura del rivestimento avvenuta soprattutto in questo settore. Ci sono due valori di picco di riduzione dello spessore del rivestimento a 20 kN e 50 kN, che corrispondono ai due picchi sotto pressione. Nel frattempo, lo spessore del rivestimento rimanente diminuisce con l&#39;aumento della forza di tenuta vuoto. I più bassi spessori di rivestimento rimanente con le forze azienda vuoto di 5, 20, e 50 kN, sono stati 0.905, 0.570, e 0,403 micron, rispettivamente, in cui lo spessore del rivestimento iniziale era 2,1 micron. <img alt="Figura 1" src="/files/ftp_upload/53957/53957fig1.jpg" /> Figura 1: Confronto tra ceppi limite sperimentali e formano predetto a diverse temperature. I ceppi limite formano aumentano all&#39;aumentare della temperatura, ad una velocità costante di 250 mm/ s, o equivalentemente, una velocità di deformazione di 6.26 s -1. <a href="https://www.jove.com/files/ftp_upload/53957/53957fig1large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a> <img alt="figura 2" src="/files/ftp_upload/53957/53957fig2.jpg" /> Figura 2: Diagramma Schema di conoscenza basata nuvola FE simulazione di un processo di stampaggio della lamiera. Commerciale software di simulazione FE, viene utilizzato per eseguire la simulazione ed esportare i risultati richiesti per i singoli moduli. I moduli, per esempio, formabilità, il trasferimento di calore, resistenza post-formatura (microstruttura), previsione vita utensile, progettazione di utensili, ecc, lavorano contemporaneamente e in modo indipendente nella nuvola, e quindi permettendo l&#39;integrazione di conoscenze all&#39;avanguardia da più fonti in simulazioni FE . <a href="https://www.jove.com/files/ftp_upload/53957/53957fig2large.jpg" target="_blank">Si prega di cl</a>ick qui per vedere una versione più grande di questa figura. <img alt="Figura 3" src="/files/ftp_upload/53957/53957fig3.jpg" /> Figura 3: La geometria del pezzo e strumenti per la U-forma sagomata simulazione. Gli strumenti, cioè, punzone, premilamiera e muoiono, vengono modellati utilizzando elementi rigidi. elementi shell sono utilizzati per gli elementi del pezzo da lavorare (vuoto). <a href="https://www.jove.com/files/ftp_upload/53957/53957fig3large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 4" src="/files/ftp_upload/53957/53957fig4.jpg" /> Figura 4: Evoluzione della forma in bianco per la stampa a caldo di un pannello interno della porta (visualizzato nella simulazione FE). Sinistra: Le cifre in cornici verdi rappresentano forme vuote in ogni fase di ottimizzazione, e quelli in rossotelai corrispondono alla forma vuota prima sua ottimizzazione. A destra: Necking risultati di previsione, in ogni fase di ottimizzazione. (A) I primi risultati con grande fallimento (rottura / collarino mostrati in colore rosso), (b) non sono ridotti con un po &#39;di formazione del collo dopo la prima fase di ottimizzazione, (c) finale forma del pezzo grezzo ottimizzato senza collarino visibile. <a href="https://www.jove.com/files/ftp_upload/53957/53957fig4large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 5" src="/files/ftp_upload/53957/53957fig5.jpg" /> Figura 5: Il restante distribuzione di spessore del rivestimento (visualizzato in simulazione FE) con forze di bloccaggio in bianco di: (a) 5 kN, (b) 20 kN, e (c) 50 kN, dopo 300 formano cicli a una velocità stampaggio costante di 250 mm / s. <a href="https://www.jove.com/files/ftp_upload/53957/53957fig5large.jpg" target="_blank">per favore</a>clicca qui per vedere una versione più grande di questa figura. <img alt="Figura 6" src="/files/ftp_upload/53957/53957fig6.jpg" /> Figura 6: Previsione di pressione di contatto e rimanendo spessore del rivestimento con forze di bloccaggio in bianco di: (a) 5 kN, (b) 20 kN, e (c) 50 kN, lungo il percorso curvilineo della matrice ad una velocità stampaggio costante di 250 mm / s. <a href="https://www.jove.com/files/ftp_upload/53957/53957fig6large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a>

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Knowledge Based Cloud FE Simulation of Sheet Metal Forming Processes

The following paper presents a novel FE simulation technique (KBC-FE), which reduces computational cost by performing simulations on a cloud computing environment, through the application of individual modules. Moreover, it establishes a seamless collaborative network between world leading scientists, enabling the integration of cutting edge knowledge modules into FE simulations.

La conoscenza basate su cloud FE Simulazione di stampaggio della lamiera Processi

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the ...

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12.0K Views.  Imperial College London. The following paper presents a novel FE simulation technique (KBC-FE), which reduces computational cost by performing simulations on a cloud computing environment, through the application of individual modules. Moreover, it establishes a seamless collaborative network between world leading scientists, enabling the integration of cutting edge knowledge modules into FE simulations.

Video: Knowledge Based Cloud FE Simulation of Sheet Metal Forming Processes

Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ &lambda;/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems.

This protocol outlines the simulation, fabrication and characterization of THz metamaterial absorbers. Such absorbers, when coupled with an appropriate sensor, have applications in THz imaging and spectroscopy.

Simulazione, fabbricazione e caratterizzazione di THz Assorbitori metamateriale

Metamaterials (MM),  artificial materials engineered to have properties that may not be found in  nature, have been widely explored since the first ...

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Simulation of the Planetary Interior Differentiation Processes in the Laboratory

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to that layered structure, (1) percolation of liquid metal in a solid silicate matrix by planet differentiation, and (2) inner core crystallization by subsequent planet cooling. We conduct high-pressure and high-temperature experiments to simulate both processes in the laboratory. Formation of percolative planetary core depends on the efficiency of melt percolation, which is controlled by the dihedral (wetting) angle. The percolation simulation includes heating the sample at high pressure to a target temperature at which iron-sulfur alloy is molten while the silicate remains solid, and then determining the true dihedral angle to evaluate the style of liquid migration in a crystalline matrix by 3D visualization. The 3D volume rendering is achieved by slicing the recovered sample with a focused ion beam (FIB) and taking SEM image of each slice with a FIB/SEM crossbeam instrument. The second set of experiments is designed to understand the inner core crystallization and element distribution between the liquid outer core and solid inner core by determining the melting temperature and element partitioning at high pressure. The melting experiments are conducted in the multi-anvil apparatus up to 27 GPa and extended to higher pressure in the diamond-anvil cell with laser-heating. We have developed techniques to recover small heated samples by precision FIB milling and obtain high-resolution images of the laser-heated spot that show melting texture at high pressure. By analyzing the chemical compositions of the coexisting liquid and solid phases, we precisely determine the liquidus curve, providing necessary data to understand the inner core crystallization process.

The high-pressure and high-temperature experiments described here mimic planet interior differentiation processes. The processes are visualized and better understood by high-resolution 3D imaging and quantitative chemical analysis.

Simulazione del Planetary Interior differenziazione processi in Laboratorio

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to ...

Picoinjection of Microfluidic Drops Without Metal Electrodes

Existing methods for picoinjecting reagents into microfluidic drops require metal electrodes integrated into the microfluidic chip. The integration of these electrodes adds cumbersome and error-prone steps to the device fabrication process. We have developed a technique that obviates the needs for metal electrodes during picoinjection. Instead, it uses the injection fluid itself as an electrode, since most biological reagents contain dissolved electrolytes and are conductive. By eliminating the electrodes, we reduce device fabrication time and complexity, and make the devices more robust. In addition, with our approach, the injection volume depends on the voltage applied to the picoinjection solution; this allows us to rapidly adjust the volume injected by modulating the applied voltage. We demonstrate that our technique is compatible with reagents incorporating common biological compounds, including buffers, enzymes, and nucleic acids.

We have developed a technique for picoinjecting microfluidic drops that does not require metal electrodes. As such, devices incorporating our technique are simpler to fabricate and to use.

Picoinjection di Microfluidic Gocce senza elettrodi in metallo

Existing methods for picoinjecting reagents into microfluidic drops require metal electrodes integrated into the microfluidic chip. The integration of ...

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

Area selettiva Modifica della Silicon bagnabilità della superficie da impulsi laser UV irradiazione in ambiente liquido

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Visualizing Hyporheic Flow Through Bedforms Using Dye Experiments and Simulation

Advective exchange between the pore space of sediments and the overlying water column, called hyporheic exchange in fluvial environments, drives solute transport in rivers and many important biogeochemical processes. To improve understanding of these processes through visual demonstration, we created a hyporheic flow simulation in the multi-agent computer modeling platform NetLogo. The simulation shows virtual tracer flowing through a streambed covered with two-dimensional bedforms. Sediment, flow, and bedform characteristics are used as input variables for the model. We illustrate how these simulations match experimental observations from laboratory flume experiments based on measured input parameters. Dye is injected into the flume sediments to visualize the porewater flow. For comparison virtual tracer particles are placed at the same locations in the simulation. This coupled simulation and lab experiment has been used successfully in undergraduate and graduate laboratories to directly visualize river-porewater interactions and show how physically-based flow simulations can reproduce environmental phenomena. Students took photographs of the bed through the transparent flume walls and compared them to shapes of the dye at the same times in the simulation. This resulted in very similar trends, which allowed the students to better understand both the flow patterns and the mathematical model. The simulations also allow the user to quickly visualize the impact of each input parameter by running multiple simulations. This process can also be used in research applications to illustrate basic processes, relate interfacial fluxes and porewater transport, and support quantitative process-based modeling.

This manuscript describes how to create regular bedforms in a flume, visualize flow through the bedforms, and use computer simulations to simulate the hyporheic flow. The computer simulations compare well with the experimental observations. This coupled simulation and experiment is well-suited for both research and educational purposes.

Visualizzare iporreico flusso Attraverso Bedforms Utilizzando Esperimenti Dye e Simulazione

Advective exchange between the pore space of sediments and the overlying water column, called hyporheic exchange in fluvial environments, drives solute ...

Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation

Shape Memory Alloys (SMA) using elastocaloric cooling processes have the potential to be an environmentally friendly alternative to the conventional vapor compression based cooling process. Nickel-Titanium (Ni-Ti) based alloy systems, especially, show large elastocaloric effects. Furthermore, exhibit large latent heats which is a necessary material property for the development of an efficient solid-state based cooling process. A scientific test rig has been designed to investigate these processes and the elastocaloric effects in SMAs. The realized test rig enables independent control of an SMA&#39;s mechanical loading and unloading cycles, as well as conductive heat transfer between SMA cooling elements and a heat source/sink. The test rig is equipped with a comprehensive monitoring system capable of synchronized measurements of mechanical and thermal parameters. In addition to determining the process-dependent mechanical work, the system also enables measurement of thermal caloric aspects of the elastocaloric cooling effect through use of a high-performance infrared camera. This combination is of particular interest, because it allows illustrations of localization and rate effects &#8212; both important for efficient heat transfer from the medium to be cooled.
The work presented describes an experimental method to identify elastocaloric material properties in different materials and sample geometries. Furthermore, the test rig is used to investigate different cooling process variations. The introduced analysis methods enable a differentiated consideration of material, process and related boundary condition influences on the process efficiency. The comparison of the experimental data with the simulation results (of a thermomechanically coupled finite element model) allows for better understanding of the underlying physics of the elastocaloric effect. In addition, the experimental results, as well as the findings based on the simulation results, are used to improve the material properties.

Experimental methods for investigation of solid state cooling processes and characterization of elastocaloric material properties of Shape Memory Alloys (SMA) are presented. A custom-built test rig has been designed for controlling and comprehensive monitoring of elastocaloric cooling processes. Furthermore, it provides a validation platform for thermomechanically coupled modeling approaches.

Metodi sperimentali per le indagini di memoria di forma a base processi di raffreddamento Elastocaloric e validazione del modello

Shape Memory Alloys (SMA) using elastocaloric cooling processes have the potential to be an environmentally friendly alternative to the conventional vapor ...

Simulation of Human-induced Vibrations Based on the Characterized In-field Pedestrian Behavior

For slender and lightweight structures, vibration serviceability is a matter of growing concern, often constituting the critical design requirement. With designs governed by the dynamic performance under human-induced loads, a strong demand exists for the verification and refinement of currently available load models. The present contribution uses a 3D inertial motion tracking technique for the characterization of the in-field pedestrian behavior. The technique is first tested in laboratory experiments with simultaneous registration of the corresponding ground reaction forces. The experiments include walking persons as well as rhythmical human activities such as jumping and bobbing. It is shown that the registered motion allows for the identification of the time variant pacing rate of the activity. Together with the weight of the person and the application of generalized force models available in literature, the identified time-variant pacing rate allows to characterize the human-induced loads. In addition, time synchronization among the wireless motion trackers allows identifying the synchronization rate among the participants. Subsequently, the technique is used on a real footbridge where both the motion of the persons and the induced structural vibrations are registered. It is shown how the characterized in-field pedestrian behavior can be applied to simulate the induced structural response. It is demonstrated that the in situ identified pacing rate and synchronization rate constitute an essential input for the simulation and verification of the human-induced loads. The main potential applications of the proposed methodology are the estimation of human-structure interaction phenomena and the development of suitable models for the correlation among pedestrians in real traffic conditions.

A protocol is presented for the characterization of the in-field pedestrian behavior and the simulation of the resulting structural response. Field-tests demonstrate that the in situ identified pacing rate and synchronization rate among the participants constitute an essential input for the simulation and verification of the human-induced loads.

Simulazione di vibrazioni indotte dall&#39;uomo Sulla base della caratterizzato campo pedonale Comportamento

For slender and lightweight structures, vibration serviceability is a matter of growing concern, often constituting the critical design requirement. With ...

Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid compartment is correctly assembled, thus providing a thin liquid layer and a vacuum seal. This protocol also includes a number of tests necessary to perform during sample loading in order to ensure correct assembly. Once the sample is loaded in the electron microscope, the liquid thickness needs to be measured. Incorrect assembly may result in a too-thick liquid, while a too-thin liquid may indicate the absence of liquid, such as when a bubble is formed. Finally, the protocol explains how images are taken and how dynamic processes can be studied. A sample containing AuNPs is imaged both in pure water and in saline.

This protocol describes the operation of a liquid flow specimen holder for scanning transmission electron microscopy of AuNPs in water, as used for the observation of nanoscale dynamic processes.

Lo studio dei processi dinamici di dimensioni nano oggetti in liquidi di utilizzare la scansione microscopia elettronica a trasmissione

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a ...

Study of Siphon Breaker Experiment and Simulation for a Research Reactor

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent this outflow, a control device is required. A siphon breaker is a type of safety device that can be utilized to control the loss of coolant water effectively.
To analyze the characteristics of siphon breaking, a real-scale experiment was conducted. From the results of the experiment, it was found that there are several design factors that affect the siphon breaking phenomenon. Therefore, there is a need to develop a theoretical model capable of predicting and analyzing the siphon breaking phenomenon under various design conditions. Using the experimental data, it was possible to formulate a theoretical model that accurately predicts the progress and the result of the siphon breaking phenomenon. The established theoretical model is based on fluid mechanics and incorporates the Chisholm model to analyze two-phase flow. From Bernoulli&#39;s equation, the velocity, quantity, undershooting height, water level, pressure, friction coefficient, and factors related to the two-phase flow could be obtained or calculated. Moreover, to utilize the model established in this study, a siphon breaker analysis and design program was developed. The simulation program operates on the theoretical model basis and returns the result as a graph. The user can confirm the possibility of the siphon breaking by checking the shape of the graph. Furthermore, saving the entire simulation result is possible and it can be used as a resource for analyzing the real siphon breaking system.
In conclusion, the user can confirm the status of the siphon breaking and design the siphon breaker system using the program developed in this study.

The siphon breaking phenomenon was investigated experimentally and a theoretical model was proposed. A simulation program based on the theoretical model was developed and the results of the simulation program were compared with experimental results. It was concluded that the results of the simulation program matched the experimental results well.

Studio di simulazione e sifone Breaker esperimento per un reattore di ricerca

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent ...

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide electronics community. One of its hallmark features is the existence of a critical LAO thickness of 4 unit-cells (uc) for interfacial conductivity to emerge. Although electrostatic mechanisms have been proposed in the past to describe the existence of this critical thickness, the importance of chemical defects has been recently accentuated. Here, we describe the growth of metal/LAO/STO heterostructures in an ultra-high vacuum (UHV) cluster system combining pulsed laser deposition (to grow the LAO), magnetron sputtering (to grow the metal) and X-ray photoelectron spectroscopy (XPS). We study step by step the formation and evolution of the q2DES and the chemical interactions that occur between the metal and the LAO/STO. Additionally, magnetotransport experiments elucidate on the transport and electronic properties of the q2DES. This systematic work not only demonstrates a way to study the electrostatic and chemical interplay between the q2DES and its environment, but also unlocks the possibility to couple multifunctional capping layers with the rich physics observed in two-dimensional electron systems, allowing the fabrication of new types of devices.

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

We fabricate metal/LaAlO3/SrTiO3 heterostructures using a combination of pulsed laser deposition and in situ magnetron sputtering. Through magnetotransport and in situ X-ray photoelectron spectroscopy experiments, we investigate the interplay between electrostatic and chemical phenomena of the quasi two-dimensional electron gas formed in this system.