Tandem Solar Cells from Solution-Processed CdTe and PbS Quantum Dots Using a ZnTe–ZnO Tunnel Junction

Crisp, Ryan W.,Pach, Gregory F.,Kurley, J. Matthew,France, Ryan M.,Reese, Matthew O.,Nanayakkara, Sanjini U.,MacLeod, Bradley A.,Talapin, Dmitri V.,Beard, Matthew C.,Luther, Joseph M. American Chemical Society 2017 Nano letters Vol.17 No.2

<P>We developed a monolithic CdTe–PbS tandem solar cell architecture in which both the CdTe and PbS absorber layers are solution-processed from nanocrystal inks. Due to their tunable nature, PbS quantum dots (QDs), with a controllable band gap between 0.4 and ∼1.6 eV, are a promising candidate for a bottom absorber layer in tandem photovoltaics. In the detailed balance limit, the ideal configuration of a CdTe (<I>E</I><SUB>g</SUB> = 1.5 eV)–PbS tandem structure assumes infinite thickness of the absorber layers and requires the PbS band gap to be 0.75 eV to theoretically achieve a power conversion efficiency (PCE) of 45%. However, modeling shows that by allowing the thickness of the CdTe layer to vary, a tandem with efficiency over 40% is achievable using bottom cell band gaps ranging from 0.68 and 1.16 eV. In a first step toward developing this technology, we explore CdTe–PbS tandem devices by developing a ZnTe–ZnO tunnel junction, which appropriately combines the two subcells in series. We examine the basic characteristics of the solar cells as a function of layer thickness and bottom-cell band gap and demonstrate open-circuit voltages in excess of 1.1 V with matched short circuit current density of 10 mA/cm<SUP>2</SUP> in prototype devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2017/nalefd.2017.17.issue-2/acs.nanolett.6b04423/production/images/medium/nl-2016-04423k_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl6b04423'>ACS Electronic Supporting Info</A></P>

Study of Non-Newtonian fluid flow in porous media at core scale using analytical approach

Ryan Kurniawan Santoso,Iqbal Fauzi,Miftah Hidayat,Boni Swadesi,Bilal Maydika Aslam,Taufan Marhaendrajana 한국자원공학회 2018 Geosystem engineering Vol.21 No.1

Characterizing in situ polymer rheology in porous media is critical before further implementation of polymer injection in oilfield. Polymer as non-Newtonian fluid has unique behavior whose viscosity changes over various shear rate. This behavior creates unsuitable conditions which can lead to ineffective sweep efficiency improvement. The challenging issue in characterizing the in situ polymer rheology is how to construct the in situ Power Law model since the in situ viscosity cannot be measured directly. In this study, we use an analytical model to construct the in situ Power Law model. The model combines material balance equation, modified Darcy equation for non-Newtonian fluid flow, and equation of state. The model is solved for early (transient) time and late (steady-state) time. Coreflooding results in Berea Sandstone with 2000 and 500 ppm HPAM polymer injection are used for model’s simulations. Rheometer measurements are also used for comparison. The overall simulation results show there is no difference in flow behavior index between rheometer and porous media. The same fluid definitely gives the same flow behavior index through different measurement methods. However, there is significant difference in flow consistency index. It is caused by the effect of porous media’s tortuosity. The quantity of the skin parameter also depicts the thinning and thickening phenomena.

치환 환기를 이용한 대기중 부유 분진 감소

Ryan Johnson,Chris Burroughs,김동규(번역자) 대한설비공학회 2023 설비저널 Vol.52 No.2

Novel insight into pressurization of the male and female urethra through application of a multi-channel fibre-optic pressure transducer: Proof of concept and validation

Ryan E. Stafford,John Arkwright,Phil G. Dinning,Wolbert van den Hoorn,Paul W. Hodges 대한비뇨의학회 2020 Investigative and Clinical Urology Vol.61 No.5

Purpose: To confirm feasibility of recording pressure along the length of the urethra using a multi-sensor fibre-optic pressure catheter; to identify the spatial and temporal features of changes in pressure along the urethra at sites related to specific striated pelvic floor muscles; and to investigate the relationship between urethral pressures and activation of individual pelvic floor muscles estimated from ultrasound imaging. Materials and Methods: Proof-of-concept study including one male (47 years old) and one female (33 years old). A multi-sensor fibre optic pressure catheter (10 mm sensor separation) was inserted into the urethra. Pressure data were recorded simultaneously with trans-perineal ultrasound imaging measures of pelvic floor muscle activity during sub-maximal and maximal voluntary contractions and evoked coughs. Results: Pressure changes along the urethra were recorded in all tasks in both participants. Face validity of interpretation of pressure measures with respect to individual muscles was supported by correlation with ultrasound-measured displacements induced by the relevant muscles. Onset of pressure increase occurred in a distal to proximal sequence in the urethra of the male but not the female during voluntary contraction. Peak urethral pressures varied in location, timing and amplitude between tasks. Evoked cough induced in the greatest urethral pressure increase across all tasks for both participants. Conclusions: The high spatial resolution pressure catheter provide viable and valid recordings of urethral pressure in a male and female. Data provide preliminary evidence of sex differences in spatial and temporal distribution of urethral pressure changes.

Influence of turbulence modeling on CFD simulation results of tornado-structure interaction

Ryan Honerkamp,Zhi Li,Gui-rong Yan,Kakkattukuzhy M. Isaac 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.35 No.2

Tornadic wind flow is inherently turbulent. A turbulent wind flow is characterized by fluctuation of the velocity in the flow field with time, and it is a dynamic process that consists of eddy formation, eddy transportation, and eddy dissipation due to viscosity. Properly modeling turbulence significantly increases the accuracy of numerical simulations. The lack of a clear and detailed comparison between turbulence models used in tornadic wind flows and their effects on tornado induced pressure demonstrates a significant research gap. To bridge this research gap, in this study, two representative turbulence modeling approaches are applied in simulating real-world tornadoes to investigate how the selection of turbulence models affects the simulated tornadic wind flow and the induced pressure on structural surface. To be specific, LES with Smagorinsky-Lilly Subgrid and k-ω are chosen to simulate the 3D full-scale tornado and the tornado-structure interaction with a building present in the computational domain. To investigate the influence of turbulence modeling, comparisons are made of velocity field and pressure field of the simulated wind field and of the pressure distribution on building surface between the cases with different turbulence modeling.

A Study of the US & China trade dispute resolution Concerning on ADR of the Proposed Modification of Action Pursuant to Section 301

Ryan Sungpyo Sohn 한국관세학회 2018 한국관세학회 학술대회 Vol.2018 No.11

On July 10, 2018, the Office of the U.S. Trade Representative (USTR) issued a statement on proposed action of an additional 10% duty on products of China worth approximately $200 billion. The USTR lists out 6,031 tariff subheadings in an annex to the announcement that will be subject to the 10% ad valorem duty. This action by the USTR is in response to a directive from the President to identify additional trade remedy actions that the US could take in response to China’s retaliatory tariffs based on US imposition of 25% tariffs on $34 billion in Chinese imports. The USTR will seek public comments and will hold a public hearing for the proposed additional tariffs. Thus this is the right time to suggest alternative dispute resolution initiating such as arbitration and mediation.

LECTURES ON DIFFERENTIAL GEOMETRY OF AFFINE HYPERSURFACES TAEGU,1995

RYAN, PATRICK J. TOPOLOGY AND GEOMETRY RESEARCH CENTER 1995 Proceedings of the Topology and Geometry Research Vol.6 No.-

OECD/NEA Benchmark for Uncertainty Analysis in Modeling (UAM) for LWRs – Summary and Discussion of Neutronics Cases (Phase I)

RYAN N. BRATTON,M.AVRAMOVA,K. IVANOV 한국원자력학회 2014 Nuclear Engineering and Technology Vol.46 No.3

A Nuclear Energy Agency (NEA), Organization for Economic Co-operation and Development (OECD) benchmark forUncertainty Analysis in Modeling (UAM) is defined in order to facilitate the development and validation of availableuncertainty analysis and sensitivity analysis methods for best-estimate Light water Reactor (LWR) design and safetycalculations. The benchmark has been named the OECD/NEA UAM-LWR benchmark, and has been divided into three phaseseach of which focuses on a different portion of the uncertainty propagation in LWR multi-physics and multi-scale analysis. Several different reactor cases are modeled at various phases of a reactor calculation. This paper discusses Phase I, known asthe “Neutronics Phase”, which is devoted mostly to the propagation of nuclear data (cross-section) uncertainty throughoutsteady-state stand-alone neutronics core calculations. Three reactor systems (for which design, operation and measured dataare available) are rigorously studied in this benchmark: Peach Bottom Unit 2 BWR, Three Mile Island Unit 1 PWR, andVVER-1000 Kozloduy-6/Kalinin-3. Additional measured data is analyzed such as the KRITZ LEU criticality experiments andthe SNEAK-7A and 7B experiments of the Karlsruhe Fast Critical Facility. Analyzed results include the top five neutronnuclidereactions, which contribute the most to the prediction uncertainty in keff, as well as the uncertainty in key parameters ofneutronics analysis such as microscopic and macroscopic cross-sections, six-group decay constants, assembly discontinuityfactors, and axial and radial core power distributions. Conclusions are drawn regarding where further studies should be done toreduce uncertainties in key nuclide reaction uncertainties (i.e.: 238U radiative capture and inelastic scattering (n, n’) as well asthe average number of neutrons released per fission event of 239Pu).

Synthesis of Permalloy (Ni-Fe) Nanosheets through Sonoelectrochemical Methods and its Magnetic Properties

Ryan Rhee,Kyounghoon Moon,Bongyoung Yoo 한국표면공학회 2018 한국표면공학회지 Vol.51 No.4

Permalloy(Ni80-Fe20) which is known for its soft magnetic properties is a well-known material that has been studied intensively. Permalloy nanoflakes were fabricated with the combination of electrodeposition and sonication process. Ultrasonic power was applied to the deposited alloy which produced nanoflakes in forms of sheet. High internal stress created cracks which helped the peeling of permalloy into nanosheets. Because of shape anisotropy, flakes could be aligned by magnetic field. The magnetic properties of the nanosheets were observed, and the variation of magnetic properties with the alignment of flake was also investigated.

Standardization and Estimation of the Number of Factors for Panel Data

Ryan Greenaway-McGrevy,한치록,설동규 한국계량경제학회 2012 계량경제학보 Vol.23 No.2

Practitioners often standardize panel data before estimating a factor model. In this paper we show an example that the standardization leads to inconsistent estimation of the factor number. When the common component exhibits strong heteroskedasticity, the conventional eigenvalue-based decompositions are consistent but standardization does not necessarily result in consistent estimation. To overcome this issue, we recommend using a “minimum-rule” whereby the minimum factor-number estimated from both the conventional and standardized panel is used. Monte Carlo studies and an empirical application are provided.