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N-doped carbon/FeCoCu catalysts exhibit excellent ORR performance, demonstrating outstanding rechargeability in Zn–air batteries. DFT calculations reveal enhanced conductivity and a favorable surface electronic structure for oxygen reactions.
Estimating spectral plane-of-array (POA) solar irradiance on inclined surfaces is an important step in the design and performance evaluation of both photovoltaic and concentrated solar plants. This work introduces a fast, line-by-line spectral, Monte Carlo (MC) radiative transfer model approach to simulate anisotropic distributions of shortwave radiation through the atmosphere as photon bundles impinge on inclined surfaces. This fast Monte Carlo approach reproduces the angular distribution of solar irradiance without the undesirable effects of spatial discretization and thus computes detailed POA irradiance values on surfaces at any orientation and also when surfaces are subjected to the anisotropic ground and atmospheric scattering. Polarization effects are also easily incorporated into this approach that can be considered as direct numerical simulation of the physics involved. Here, we compare our Monte Carlo radiative transfer model with the most widely used empirical transposition model, Perez4, under various conditions. The results show that the Perez4 model reproduces the more detailed Monte Carlo simulations with less than 10% deviation under clear skies for all relevant surface tilt and azimuth angles. When optically thin clouds are present, observed deviations are larger, especially when the receiving surface is strongly tilted. Deviations are also observed for large azimuth angle differences between the receiving surface and the solar position. When optically thick clouds are present, the two models agree within 15% deviation for nearly all surface orientation and tilt angles. The overall deviations are smaller when compared with cases for optically thin clouds. The Perez4 model performs very well (6.0% deviation) in comparison with the detailed MC simulations for all cases, thus validating its widespread use for practical solar applications. When detailed atmospheric profiles and cloud optical properties are available, the proposed fast Monte Carlo radiative model reproduces accurate spectral and angular POA irradiance levels for various atmospheric and cloud cover conditions, surface orientations, and different surface and ground properties.
Total hemispherical emissivities are a commonly used property in radiative heat transfer analysis. Measurements made in the course of testing become far more useful to thermal analysts if they are compiled with a sufficient level of detail, and summarized in a manner that allows the most appropriate value or trend to be located quickly. This report collects emissivity measurements from recent years, made in the course of testing metallic surfaces at Sandia's Radiant Heat Test Facility, and compares them to a selection of previous summary documents. These measurements are organized by material type, surface finish, and degree of oxidation. The comparisons also consider the temperature dependence of total hemispherical emissivity. Materials considered include Inconel 600, SS304, 17-4PH SS, silicon carbide, and aluminum alloys. A limited selection of high-temperature paints and other surface coatings are also considered. Recommendations are made for frequency of measurements and level of detail in reporting emissivities in future test series. A more limited scope is recommended for the use of high-temperature paints at Sandia's Radiant Heat Test Facility; pre-oxidation of Inconel and stainless steel surfaces is preferred in many circumstances.
In evaluating the state-of-the-art spalling techniques, the key factor that is missing is the control of crack propagation, which is responsible for low quality wafers due to high surface roughness and Total Thickness Variation, TTV. This project has shown that acoustic waves can alter the conditions at the crack tip during thermal spalling, modifying the propagation speed and the stress field around it (stress intensity factor, K). Both factors are directly related to the roughness of the spalled surface, so as we control speed and stress, we can fine-tune the surface roughness through the entire wafer as suggested by Arakawa.
Surrogate laboratory experiments were conducted to understand how cavities surrounding an explosive event in a bounded material influence the transfer of energy to the surface of the material. Exploding bridgewires were detonated in a cavity that had been created in an optically accessible polymer material. The shock propagation was investigated through five paths, three through spherical cavities of varying size filled with air, one without a cavity and one in air. Shock propagation was imaged using the schlieren technique. The path effects were determined by measuring energy at the polymer surface using a pressure sensor. All cavities were successful at reducing the peak pressure nearly 100% from the case without a cavity, a reduction close to air. The degree of reduction was not uniform over all frequencies. Overall, our findings suggest that cavities influence both the amount and frequency content of the energy transfer from source to surface.
A first device is provided. The first device includes an organic light emitting device, which further comprises a first electrode, a second electrode, and an organic emissive layer disposed between the first and second electrode. Preferably, the second electrode is more transparent than the first electrode. The organic emissive layer has a first portion shaped to form an indentation in the direction of the first electrode, and a second portion shaped to form a protrusion in the direction of the second electrode. The first device may include a plurality of organic light emitting devices. The indentation may have a shape that is formed from a partial sphere, a partial cylinder, a pyramid, or a pyramid with a mesa, among others. The protrusions may be formed between adjoining indentations or between an indentation and a surface parallel to the substrate.
Embodiments of the present invention are directed toward devices, systems, and method for conducting assays using sedimentation. In one example, a method includes layering a mixture on a density medium, subjecting sedimentation particles in the mixture to sedimentation forces to cause the sedimentation particles to move to a detection area through a density medium, and detecting a target analyte in a detection region of the sedimentation channel. In some examples, the sedimentation particles and labeling agent may have like charges to reduce non-specific binding of labeling agent and sedimentation particles. In some examples, the density medium is provided with a separation layer for stabilizing the assay during storage and operation. In some examples, the sedimentation channel may be provided with a generally flat sedimentation chamber for dispersing the particle pellet over a larger surface area.
A supported PV assembly may include a PV module comprising a PV panel and PV module supports including module supports having a support surface supporting the module, a module registration member engaging the PV module to properly position the PV module on the module support, and a mounting element. In some embodiments the PV module registration members engage only the external surfaces of the PV modules at the corners. In some embodiments the assembly includes a wind deflector with ballast secured to a least one of the PV module supports and the wind deflector. An array of the assemblies can be secured to one another at their corners to prevent horizontal separation of the adjacent corners while permitting the PV modules to flex relative to one another so to permit the array of PV modules to follow a contour of the support surface.
A method and hybrid radiator-cooling apparatus for implementing enhanced radiator-cooling are provided. The hybrid radiator-cooling apparatus includes an air-side finned surface for air cooling; an elongated vertically extending surface extending outwardly from the air-side finned surface on a downstream air-side of the hybrid radiator; and a water supply for selectively providing evaporative cooling with water flow by gravity on the elongated vertically extending surface.
A system for draining a containment vessel may include a drain inlet located in a lower portion of the containment vessel. The containment vessel may be at least partially filled with a liquid, and the drain inlet may be located below a surface of the liquid. The system may further comprise an inlet located in an upper portion of the containment vessel. The inlet may be configured to insert pressurized gas into the containment vessel to form a pressurized region above the surface of the liquid, and the pressurized region may operate to apply a surface pressure that forces the liquid into the drain inlet. Additionally, a fluid separation device may be operatively connected to the drain inlet. The fluid separation device may be configured to separate the liquid from the pressurized gas that enters the drain inlet after the surface of the liquid falls below the drain inlet.
An apparatus for growing a crystalline sheet from a melt includes a cold block assembly. The cold block assembly may include a cold block and a shield surrounding the cold block and being at an elevated temperature with respect to that of the cold block, the shield defining an opening disposed along a surface of the cold block proximate a melt surface that defines a cold area comprising a width along a first direction of the cold block, the cold area operable to provide localized cooling of a region of the melt surface proximate the cold block. The apparatus may further include a crystal puller arranged to draw a crystalline seed in a direction perpendicular to the first direction when the cold block assembly is disposed proximate the melt surface.
Packaging high average power laser diode arrays that generate heat at an area average flux in excess of 1 kW·cm -2 is a significant engineering challenge. While liquid microchannel coolers have demonstrated up to 11.9 kW·cm -2 , two-phase microchannel array coolers have not achieved 1 kW cm -2 due to critical heat flux and flow instabilities. In the current study, flow boiling heat transfer was characterized by a 1 × 10 mm heated zone centered over a 5 × 10 mm array of 125 very small channels (45 × 200 μm) with R134a as the phase change fluid. The high aspect ratio channels (4.4:1) were manufactured using MEMS fabrication techniques, which yielded a large heat transfer surface area to volume ratio. A test facility was used to characterize the heat transfer performance of boiling R134a over a range of saturation temperatures (15°C to 25°C), mass fluxes (735-2230 kg·m -2 ·s -1 ), and heat duties (< 110.3 W). During the tests, the calculated outlet vapor quality exceeded 61%, and the base heat flux at the heater reached a maximum of 1.1 kW·cm -2 . The resulting average experimental flow boiling heat transfer coefficients are found to be as large a 13.4 kW·m -2 ·K -1 over the approximately 3 mm two-phase region, with an average uncertainty of ± 2.72%. A substantial amount of heat was spread downstream via the low thermal resistance silicon floor. Specifically, between 29.5% and 55.1% of the heat dissipated in the two-phase region was dissipated over the heater. Finally, the remaining heat dissipated in the two-phase region was dissipated in the 2 mm of channel downstream of the heater. This suggests that heat spreading from the hotspot played a vital role in dissipating the heat load.
We formulate and solve the problem of biaxial bending of an isotropic plate with two coaxial through cracks of identical lengths by distributed bending moments applied at infinity under the action of external load symmetric about the cracks with regard for the contact zone of their faces and in the presence of plastic zones near the crack tips, where the Tresca plasticity conditions are satisfied in the form of a surface layer or a plastic hinge. By using complex potentials of the plane problem and the classical theory of bending of the plates, we obtain an analytic solution of the problem in the class of functions bounded in the vicinity of the vertices of the plastic zones. The length of the plastic zones and the crack-tip opening displacements are found numerically.
Jefferson Proving Ground (JPG), located near Madison, Indiana is a 55,000-acre site with firing ranges for test firing of conventional munitions and depleted uranium penetrators. The penetrators were fired from three positions, but the majority (89 percent) was fired from a single location. Impacts from the penetrators along this firing line created an impact trench roughly 5 meters (m) to 8 m wide, 1,200 m long, and 1 m deep. Periodic surface sweeps were conducted to recover test fired penetrators, but roughly 73,500 kilograms (kg) of depleted uranium (DU) still remain at JPG. Co-located and intermingled with the penetrators are unexploded ordnance (UXO), making complete recovery and site restoration both risky and costly. Understanding the transport and fate of the depleted uranium at JPG was critical to assessing the potential radiological risks posed to human health and the environment from the penetrators and associated impacted soils on site. JPG is underlain by loess (wind-blown silt), glacial till, and carbonate bedrock, and transected by surface water (Big Creek, Middle Fork Creek, and smaller tributaries). The Army determined site-specific values of the uranium distribution coefficient (Kd) for each of the underlying units. The Army evaluated uranium transport and fate in column, groundwater, and surface water models. The Army used the Residual Radiation (RESRAD)- OFFSITE code to complete the uranium risk assessment for a period of 1,000 years. Results from the site-specific Kd tests are presented in this paper along with its use and results in assessing transport, fate, and potential risks associated with exposure to the penetrators remaining at JPG. The authors supported the decommissioning activities discussed in this paper under the direction of and with funding from the U.S. Army, specifically the U.S. Army Installation Management Command (IMCOM, Robert N. Cherry), U.S. Army Environmental Command (AEC, Joan F. Jackson), and U.S. Army Corps of Engineers (USACE, Andrew [Brooks] Evens). (authors)
Spatial atomic layer deposition (SALD) is a promising technology with the aim of combining the advantages of excellent uniformity and conformity of temporal atomic layer deposition (ALD), and an industrial scalable and continuous process. In this manuscript, an experimental and numerical combined model of atmospheric SALD system is presented. To establish the connection between the process parameters and the growth efficiency, a quantitative model on reactant isolation, throughput, and precursor utilization is performed based on the separation gas flow rate, carrier gas flow rate, and precursor mass fraction. The simulation results based on this model show an inverse relation between the precursor usage and the carrier gas flow rate. With the constant carrier gas flow, the relationship of precursor usage and precursor mass fraction follows monotonic function. The precursor concentration, regardless of gas velocity, is the determinant factor of the minimal residual time. The narrow gap between precursor injecting heads and the substrate surface in general SALD system leads to a low Péclet number. In this situation, the gas diffusion act as a leading role in the precursor transport in the small gap rather than the convection. Fluid kinetics from the numerical model is independent of the specific structure, which is instructive for the SALD geometry design as well as its process optimization.
Traditional corrosion inhibitors are bio-toxic chemicals with organic components that bond to the fresh metal surface and thus isolate them from corrosive environments. The shortcoming of these inhibitors is that they are less effective in high-temperature and high-pressure environments, and where corrosion scale is formed or particulates are deposited. In this paper, we describe a novel green inorganic inhibitor made of environmentally friendly and cost-effective geo-material that was developed for high-temperature and high-pressure environments, particularly under scale-forming conditions. It inhibits corrosion by enhancing the protectiveness of corrosion scale. In contrast to traditional corrosion inhibitors which are efficient for bare surface corrosion but not effective with scale, the novel inhibitor has no effect on bare surface corrosion but greatly improves corrosion inhibition under scale-formation conditions. This is because a homogeneous scale doped with inhibitor component forms. This enhanced corrosion scale demonstrated excellent protection against corrosion. In high-pressure CO{sub 2} systems (pCO{sub 2}=10 Mpa, T=50 C and [NaCl]=1 wt%) without inhibitor, the bare-surface corrosion rate decreases from ca. 10 mm/y to 0.3 mm/year due to formation of scale. Application of a six hundred ppm solution ofthe new inorganic inhibitor reduced the corrosion rate to 0.01 mm/year, an additional factor of 30. The current inhibitor product was designed for application to CO{sub 2} systems that form corrosion scale, including but not limited to oil and gas wells, offshore production of oil and gas, CO{sub 2} sequestration and enhanced geothermal production involving CO{sub 2}.
The authors investigated the effects of defect density on the performance of monolayer graphene as a barrier to metal diffusion. The defects were introduced to the graphene by controlled ultraviolet-ozone irradiation. The barrier performance of pristine graphene was found to be superior to that of defective graphene at temperatures up to 700 °C. Changes in surface morphology were more prevalent in the defective graphene-based films than in the pristine graphene-based film; the thermal stability of graphene films depends on their defect density. Defect density was found to be a determining factor in the barrier performance of graphene.
Effective surface passivation of crystalline silicon (c-Si) surface by reducing the carrier recombination rate has led to modern c-Si solar cells with efficiencies > 25% in both laboratory and industrial settings. Typical mainstream surface passivation techniques include high-temperature silicon oxide (SiOx), amorphous silicon (a-Si:H), hydrogen-rich silicon nitride (SiNx), and aluminum oxide (Al2O3) [1]. They have demonstrated excellent surface recombination velocity of < 1 cm/s owing to both chemical passivation (via the hydrogen saturation of Si dangling bonds at the c-Si surface), and field-effect passivation (via the band bending from the fixed charge of the dielectric layers). Recently, several groups have studied solution-based organic materials for c-Si passivation, including bis(trifluoromethane)sulfonimide (TFSI), polystyrenesulfonate, and Nafion [2, 3] via spin or dip coating. All films were processed at ambient room temperature, and a high lifetime of 12 ms, as well as a low saturation current density (J0) of 16 fA/cm2, have been demonstrated using Nafion passivation [2]. However, despite the air instability, Nafion has several advantages when introduced to PV applications: (a) Wafer quality can be measured at high throughput after several process stages. (b) It is compatible with PL mapping, compared to HF liquid passivation which cannot be performed in room ambient. (c) Nafion process is fast and poses fewer constraints on process complexity, and cleanness, compared to Al2O3 and a-Si:H passivation. (d) Nafion is the ideal room temperature passivation, which can be applied onto a small fragment of a degraded module to investigate microscopic mechanisms when studying degradation mechanisms. Edge passivation is needed for advanced characterization tests such as Electron Paramagnetic Resonance (EPR), Electrically Detected Magnetic Resonance (EDMR), Deep Level Transient Spectroscopy (DLTS), local cell current-voltage (J-V), and Suns-Voc. In such cases, the laser-damaged minicell edges will obscure the true degradation mechanisms, and Nafion can effectively passivate them without causing further degradation through elevated-temperature processes. In this contribution, we show the passivation results of Nafion on bare nCz and compare it with a Al2O3 witness. We highlight the importance of edge pre-treatment before Nafion to achieve good passivation. We show that Nafion can reach decent passivation without undergoing high-temperature processes. We also explore the temperature dependency of Nafion through photoluminescence (PL) study and demonstrate the application of Nafion under cryogenic temperature (~6 K) through EPR. Our results reveal that Nafion can reduce surface and edge Si dangling bonds at low temperatures. Thus, it can be used as an effective room temperature passivation technique for advanced characterization methods.