bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gold nanoparticles on nanodiamond for nanophotonic applications
Authors: Orlanducci S. , Cianchetta I. , Tamburri E. , Terranova M.L. , Cassani M. C. , Matassa R. , Rossi M. 
Published: November 2012

ABSTRACTWe present here some recent results of a research focused on the preparation of detonation nanodiamond/Au nanoparticles hybrid materials. Two different experimental routes are followed for the decoration of diamond nanoparticles by Au nanoparticles, that are in turn prepared by an innovative electroless approach.Structure and morphology at the nanoscale level of the Au-on-nanodiamond deposits have been deeply investigated by electron microscopy (FE-SEM, HR-TEM) and diffraction (XRD) techniques.Optical properties of these systems have been determined by performing scattering and UV-Vis absorption measurements, and by comparing the experimental data with simulated extinction spectra. The results highlighted very interesting plasmonic and scattering behaviors, mainly related to the high refractive index of diamond.
Heterogeneous Integration of LSI Amplifier and the Tactile Sensor Using Stacking and Through-Si-Via Techniques
Authors: Sohgawa Masayuki , Yokoyama Hokuto , Kanashima Takeshi , Okuyama Masanori , Noma Haruo 
Published: November 2012

ABSTRACTWe have developed the tactile sensor using the microcantilevers with strain gauge film which can detect normal and shear forces simultaneously. In this work, the tactile sensor and the IC amplifier have been integrated heterogeneously to shorten the wire length by chip-on-chip stacking and reduce the noise in the output voltage. Standard deviation of the noise can be reduced from 27.6 mV to 3.3 mV by heterogeneous integration of the tactile sensor and the IC amplifier using Au wire bonding. By this heterogeneous integration, the device size and wiring numbers can be reduced, and installation of more sensors is allowed on fingertips of the robot. Moreover, through-silicon-via (TSV) holes were fabricated to mount an IC amplifier on the backside of the sensor chip, instead of using Au wires. Although TSV can be fabricated successfully, resistance to sacrificial etching process is problem. As a result, Si3N4 used instead of SiO2 has improved insulation between TSVs.
Growth Stress in SiO2Formed by Oxidation of SiC
Authors: Hay Randall S. 
Published: November 2012

ABSTRACTGrowth stresses in amorphous SiO2scales formed during SiC fiber oxidation were calculated. A numerical method using Deal-Grove oxidation kinetics and shear-stress dependent SiO2viscosity was used. Initial compressive stresses in SiO2of ∼25 GPa from the 2.2× oxidation volume expansion rapidly relaxes. At >1200°C, viscous flow of amorphous SiO2further relaxes stress to negligible levels. At 700° - 900°C, axial and hoop stress at the GPa level persist in SiO2near the SiC-SiO2interface. Radial expansion of the scale causes hoop stress to become tensile, and axial stresses are driven to tensile values by the Poisson effect. These tensile stresses can be >1 GPa for thick scales formed at lower temperatures on surfaces with high curvature. Approximate analytical expressions for growth stress are discussed. Effects of viscosity variation as well as other assumptions and limitations of the calculation method are discussed.
Terahertz Detectors Based on Silicon Technology Field Effect Transistors
Authors: Knap Wojciech , Schuster Franz , Coquillat Dominique , Teppe Frédéric , Giffard Benoît , But Dmytro B. , Golenkov Oleksander G. , Sizov Fedor F. 
Published: November 2012

ABSTRACTThe concept of THz detection based on excitation of plasma waves in two-dimensional electron gas in Si FETs is one of the most attractive ones, as it makes possible the development of the large-scale integrated devices based on a conventional microelectronic technology including on-chip antennas and readout devices integration. In this work we report on investigations of Terahertz detectors based on low-cost silicon technology field effect transistors. We show that detectors, consisting of a coupling antenna and a n-MOS field effect transistor as rectifying element, are efficient for THz detection and imaging. We demonstrate that in the atmospheric window around 300 GHz, these detectors can achieve a record noise equivalent power below 10 pW/Hz0.5 and a responsivity above 90 kV/W once integrated with on-chip amplifier. We show also that they can be used in a very wide frequency range: from ∼0.2 THz up to 1.1 THz. THz detection by Si FETs pave the way towards high sensitivity silicon technology based focal plane arrays for THz imaging.
Improved hydrogen storage kinetics of nanoconfined LiBH4-MgH2 reactive hydride composites catalyzed with nickel Nanoparticles
Authors: Nielsen Thomas K. , Polanski Marek , Hansen Bjarne R. S. , Tolborg Søren , Ravnsbæk Dorthe B. , Besenbacher Flemming , Bystrzycki Jerzy , Skibsted Jørgen , Jensen Torben R. 
Published: November 2012

ABSTRACTLiBH4 and MgH2 both have high gravimetric and volumetric hydrogen storage densities. Unfortunately, their commercial application is prevented by high thermal stability and unfavorable thermodynamic properties. Combining the two hydrides leads to a new decomposition pathway with suitable enthalpy of reaction. However, the kinetics for hydrogen release remains an obstacle but can be improved by nanoconfinement in nano porous carbon materials. Here we report on nanoconfinement of 2LiBH4-MgH2 in Ni functionalized carbon aerogels. 11B MAS NMR reveals that the nanoconfined hydrides react reversibly with hydrogen whereas simultaneous differential scanning calorimetry and mass spectroscopy clearly show that nanoconfinement facilitates lower hydrogen release temperatures than ball milling. Furthermore, Ni functionalization of the nanoporous aerogel leads to even lower hydrogen release temperatures from nanoconfined 2LiBH4-MgH2.
An Efficient Implementation of Multiscale Simulation Software PNP-cDFT
Authors: Meng Da , Lin Guang , Sushko Maria L. 
Published: November 2012

ABSTRACTAn efficient implementation of PNP-cDFT, a multiscale method for computing the chemical potentials of charged species is designed and evaluated. Spatial decomposition of the multi particle system is employed in the parallelization of classical density functional theory (cDFT) algorithm. Furthermore, a truncation strategy is used to reduce the computational complexity of cDFT algorithm. The simulation results show that the parallel implementation has close to linear scalability in parallel computing environments. It also shows that the truncated versions of cDFT improve the efficiency of the methods substantially.
Rare-Earth-doped Laser Materials: Spectroscopy and Laser Properties
Authors: Merkle Larry D. 
Published: November 2012

ABSTRACTTrivalent rare earth ions in crystalline or fiber hosts are among the most successful of laser materials, but new dopant-host combinations and more detailed understanding of existing materials continue to be needed. This paper presents a few examples from the work of our team at the Army Research Laboratory, highlighting the interrelation between spectroscopic properties and laser behavior. It focuses on bulk solids, though rare-earth-doped fiber lasers are also extremely important. One system discussed is Nd:YAG, particularly concentration quenching in heavily doped ceramic YAG. Spectroscopic properties of Yb:Y2O3 and Yb:Sc2O3 help to elucidate their laser performance. Spectra indicate that Er:YAG is more promising than Er:Sc2O3 for room temperature laser operation, but that the reverse is true for operation at and somewhat above liquid nitrogen temperature.
An Educational Module to Explore what is the Role of an Electrolyte in an Electrochemical cell
Authors: Menéndez Christian , Díaz-Vázquez Liz , Mayol Ana-Rita , Cabrera Carlos R. 
Published: November 2012

ABSTRACTA general chemistry experiment has been adapted in which electrochemical principles in fuel cells are applied to the curriculum, thus bringing research into the classroom. It is well documented that students struggle in understanding redox reactions, in particular when applied to an electrochemical cell. There are three basic concepts needed to analyze these energy devices: anode, cathode and electrolyte.In the proposed experiment, undergraduate students explored the role on an electrolyte in an electrochemical cell. Inquiry based methods were used to introduce the experiment. Explanations of fundamental electrochemical concepts involved in fuel cells were introduced to the students with pre- and post-laboratory activities and experimental results discussions. The lesson for the experiment “role of an electrolyte in an electrochemical cell” was planned to improve students’ technological skills and application of knowledge acquired in daily life. The battery was made using household materials: zinc, copper and napkin paper soaked in different electrolyte solutions. Students correlated the voltage of the cells with the substances being used in the experiment and classified these as strong electrolyte, weak electrolyte or non electrolyte. A variety of assessment tools were designed and incorporated during the experience to probe students understanding in the main topics and to identify the struggles during their learning process.
Simulation of the Effect of Pressure and Solution Gas on Oil Recovery From Surfactant/Polymer Floods
Authors: Roshanfekr M. , Johns R. T. , Pope G. , Britton L. , Linnemeyer H. , Britton C. , Vyssotski A. 
Published: November 2012

Summary
Surfactant/polymer (SP) and alkali/surfactant/polymer flooding is of current interest because of the need to recover residual oil after primary and secondary recovery. If designed properly, these enhanced-oil-recovery processes can give very high oil recoveries. Microemulsion phase behavior plays a central role in process performance and is typically measured by performing salinity scans in glass pipettes at atmospheric pressure and reservoir temperature using dead crude oil from the reservoir of interest. There have been only a few experiments reported in the literature on live oil at reservoir pressure and temperature, and the importance of those experimental results is conflicting.
This paper investigates the effect of pressure and solution gas on microemulsion phase behavior and its impact on oil recovery. We examine previous data reported in the literature, and report new measurements with live oil to show that the optimum parameters can change significantly. The experiments show that while pressure induces a phase transition from upper microemulsion (Winsor Type II+) to lower microemulsion (Winsor Type II—), solution gas does the opposite. An increase in pressure decreases the optimum solubilization ratio and shifts the optimum salinity to a larger value. Adding methane to dead oil at constant pressure does the reverse. Thus, these effects are coupled and both must be taken into account. Using a numerical simulator, we show that these changes in the optimum conditions can significantly impact oil recovery if not accounted for in the SP design.
Mechanical Interaction of Multiple Fractures—Exploring Impacts of the Selection of the Spacing/Number of Perforation Clusters on Horizontal Shale-Gas Wells
Authors: Cheng Y.. 
Published: November 2012

Summary
For multistage hydraulic fracturing of horizontal wells with cased-hole completion, multiple perforation clusters are used typically to create multiple fractures in any single stage. How to place these perforation clusters is a critical issue because the number of perforation clusters to be used and the space between them significantly impact how effectively the fractures can be created in the formation. To optimize the spacing of perforation clusters, stress distributions and fracture mechanics need to be well understood.
In this study, the displacement-discontinuity method is used to construct a boundary-element model, which is able to analyze the stress distributions around multiple transverse fractures and the geometries of those fractures. With the boundary-element model, multiple cases are investigated for a different number of fractures and fracture spacings. Changes of both minimum and maximum stresses and shear stress around these fractures are illustrated first. It is found that for the cases with more than two parallel fractures, there is a strong stress concentration around the center fractures. The calculated displacements indicate that the created fractures are no longer elliptic-like, and the widths of the center fractures are reduced significantly compared with those of a single fracture. For the case of two parallel fractures, the stress concentration between two fractures also results in asymmetrical fracture shape, but the fracture widths are not reduced significantly.
This study indicates that the number and spacing of the fractures need to be selected carefully to create effective fractures with appropriate fracture geometries. The boundary-element model provides a useful tool to relate rock geomechanic properties to stress distribution and fracture geometries for multiple fractures in hydraulic fracturing of horizontal wells, which can be used as a guide to space the perforation clusters.
2D Analytical Solution of Ideal Perforation Flow
Authors: Li B.. , Sun D.. , Gladkikh M.. , Wu J.. 
Published: November 2012

SummaryCore-flow efficiency (CFE) is defined to quantitatively evaluate the flow performance of single-shot perforation. To calculate CFE, the flow rate of the ideal perforation flow in the core target is needed. The ideal flow rate is typically calculated with numerical simulators, but the computation may be time consuming and costly.This paper presents the 2D analytical solution of the steady-state flow model (mass-conservation equation) for an ideal singleshot perforation in a cylindrical core sample. The separation-of-variable method is used to solve the partial-differential equation (PDE) of the flow model. Pressure and velocity distributions in (r, z) space are obtained, along with the flow-rate distribution along the perforation tunnel.The accuracy and convergence of the analytical solution for ideal single-shot perforation flow are investigated and compared with those of the numerical solution of the commercial software ANSYS Fluent (ANSYS Fluent 12.0 User's Guide 2001). The analytical solution for the governing equation of ideal perforation flow is composed of an infinite number of Bessel functions. To compute CFE by making use of this analytical solution, the analytical solution is approximated with a limited number of Bessel functions. The approximated analytical solution is analyzed and compared with the numerical solutions from ANSYS Fluent.Further, the axial-, radial-, and radial/axial-flow geometries of an ideal single-shot perforation are characterized with their approximated analytical solutions. Interactions between the boundary condition, perforation parameters, and core parameters are investigated for these flow geometries.The analysis results show that: (1) The analytical solution has no grid effects, (2) the boundary condition of the perforated core is the dominant factor in the ideal flow rate of the perforated core, and (3) the penetration depth and anisotropic permeability are the significant factors in the flow performance of the perforated core.
Applying Fractional-Flow Theory Under the Loss of Miscibility
Authors: Ghanbarnezhad-Moghanloo Rouzbeh , Lake Larry W. 
Published: November 2012

Summary
This paper examines the limits of the Walsh and Lake (WL) method for predicting the displacement performance of solvent flood when miscibility is not achieved. Despite extensive research on the applications of fractional-flow theory, the prediction of flow performance under the loss of miscibility has not been investigated thoroughly.
We introduce the idea of an analogous first-contact miscible (FCM) flood to study miscibly degraded simultaneous water and gas (SWAG) displacements using the WL method. Furthermore, numerical simulation is used to validate the WL solution on one oil/solvent pair. In the simulations, the loss of miscibility (degradation) is attributed to either flow-associated dispersion or insufficient pressure to develop the miscibility.
1D SWAG injection simulations suggest that results of the WL method and the simulations are consistent when dispersion is limited. For the 2D displacements, the predicted optimal water-alternating-gas (WAG) ratio is accurate when the permeable medium is fairly homogeneous with a limited crossflow or is heterogeneous with a large lateral correlation length (the same size or greater than the interwell spacing).
The results suggest that the accuracy of the WL method improves as crossflow is reduced. In addition, linear growth of the mixing zone with time is observed in cases for which the predicted optimal WAG ratio is consistent with the simulation results. Hence, we conclude that the WL solution is accurate when the mixing zone grows linearly with time.
The Effects of Barium Sulfate Saturation Ratio, Calcium, and Magnesium on the Inhibition Efficiency—Part I: Phosphonate Scale Inhibitors
Authors: Shaw S.S.. S. , Sorbie K.S.. S. , Boak L.S.. S. 
Published: November 2012

Summary
Conventional phosphonate-type scale inhibitors (SIs) are commonly applied for barite-scale prevention in oil fields. The barite forms when the injection water (IW), which is usually sulfate rich, is injected into a barium-containing formation water (FW). The inhibition efficiency (IE) of barite-scale inhibitors is affected by the barium sulfate saturation ratio (SR) of the brine mix and, additionally, by the presence of divalent cations Ca2+ and Mg2+. What is less well known is that the precise balance between these factors (SR and Ca2+/Mg2+ ratio) can vary significantly for different phosphonate species. This paper presents novel IE experimental results for phosphonate-scale inhibitors DETPMP and HMTPMP (penta-phosphonates), OMTHP (hexa-phosphonate), and HMDP (tetra-phosphonate). Minimum-inhibitor-concentration (MIC) levels for each SI are established by testing a wide range of brine IW/FW mixing ratios, which changes (i) barite SR and precipitated mass, (ii) molar ratio of Ca2+/Mg2+, and (iii) the ionic strength of the brine mix.
The phosphonate SIs were categorized into two types on the basis of their MIC-vs.-percent-North Sea-seawater (NSSW) behavior. Type 1 (e.g. DETPMP and OMTHP) are affected principally by SR and are rather less sensitive to Ca2+/Mg2+ ratio although they do show some sensitivity to the latter factor. Type 2 (e.g., HMTPMP and HMDP) are severely affected by brine Ca2+/Mg2+ ratio as well as SR. To demonstrate these effects conclusively, a series of IE experiments is presented with varying [Ca2+] and [Mg2+] (which normally occurs in the field as the IW/FW ratio changes over time) and then similar experiments are repeated at a fixed Ca2+/Mg2+ molar ratio. The MIC level measured for both types of phosphonate SI always correlates very well with the barite SR at fixed Ca2+/ Mg2+ molar ratio (fixed case). In addition, we find the MICs of both types of SI are much lower in the fixed-case experiments (higher Ca2+/Mg2+ molar ratio), compared with the base case, because of the beneficial effect of higher [Ca2+]. The effects observed are important for field application of phosphonate SIs because they show how the various species are sensitive to the changing scaling problems as the %NSSW increases, in terms of SR and Ca2+/Mg2+ molar ratio. These results also give some important insights into the mechanism by which different phosphonates actually work in inhibiting barite scale.
The Effects of Barium Sulfate Saturation Ratio, Calcium, and Magnesium on the Inhibition Efficiency—Part II: Polymeric Scale Inhibitors
Authors: Shaw S.S.. S. , Sorbie K.S.. S. , Boak L.S.. S. 
Published: November 2012

Summary
In oilfield-produced waters, the barite mineral-scaling problem is a "moving target" because the seawater/formation-water (SW/ FW) mixing ratio is constantly changing. Therefore, the barite saturation ratio (SR), the yield of barite precipitate, and molar ratio Ca2+/Mg2+ in the produced waters are all evolving over time.
This paper describes the effects of SR and molar ratio Ca2+/ Mg2+ on the barium sulfate inhibition efficiency (IE) of nine polymeric scale inhibitors (SIs): phosphino poly carboxylic acid (PPCA); maleic acid ter-polymer (MAT)—a green SI; sulfonated PPCA (SPPCA); phosphino methylated polyamine (PMPA)—a poly-phosphonate; a generic P-functionalized copolymer (PFC); polyvinyl sulfonate (PVS); vinyl sulfonate acrylic acid copolymer (VS-Co); and cationic ter-polymers A and B (CTP-A and CTP-B). The behavior for polymers is compared with similar results for phosphonate SIs (Shaw et al. 2010). IE experiments were carried out for a wide range of SW/FW compositions (i.e., SR and molar ratio Ca2+/Mg2+ varying). The minimum-inhibitor-concentration (MIC) levels of these polymeric SIs sometimes correlate with the level of SR, but not always, which is because of Ca2+ and Mg2+ effects. When experiments were repeated but the produced-brine molar ratio Ca2+/Mg2+ was fixed, MICs always correlate with the level of SR for all nine polymers studied. However, it was observed that for SIs PPCA, MAT, and PFC, the base-case MICs (i.e., molar ratio Ca2+/Mg2+ varying) were less than the fixed-case MICs (molar ratio Ca2+/Mg2+ fixed), whereas in testing SPPCA, PMPA, PVS, VS-Co, and both the cationic terpolymers, the converse is true (i.e., the fixed-case MIC is less than the base-case MIC). It has been demonstrated conclusively that the high [Ca2+] in the fixed-case tests causes some SI precipitation with brine Ca2+ when PPCA is being evaluated (as PPCA-Ca). Sulfonate functional groups present on polymeric SI molecules may help to prevent such incompatibility problems encountered with brine Ca2+ (e.g., SPPCA does not precipitate as SPPCA-Ca). Low levels of brine calcium (e.g., approximately 500 to 700 ppm) can be very beneficial to the IE performance of PPCA. However, when the [Ca2+] reaches a certain level (approximately 1,000 ppm or higher), this causes some precipitation of a Ca–PPCA compound. It has been illustrated that low-to-moderate Ca2+ levels are often best, and it is concluded that this is why SIs PPCA, MAT, and PFC perform better under base-case experimental conditions (lower Ca2+ mix). It has been illustrated that PMPA behaves remarkably similarly to conventional phosphonate SIs with regard to Ca2+ and Mg2+. In fact, the behavior of PMPA suggests that it is not polymeric in nature. PVS, VS-Co, and both the cationic ter-polymers are mildly affected by divalent ions Ca2+ and Mg2+, with the latter being affected more than PVS because of the presence of carboxylate functional groups.