Pb2.28Ba1.72B10O19 Featuring Three-dimensional B-O Anionic Network with Edge-Sharing [BO4] Obtained under Ambient Pressure

2021 ◽  
Author(s):  
Siru Guo ◽  
Wenbin Zhang ◽  
Rong Yang ◽  
Min Zhang ◽  
Zhihua Yang ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Three Dimensional ◽  
Bilayer Structure ◽  
Squeezing Effect

The first borate featuring three-dimensional B-O anionic network with edge-sharing (ES) [BO4] unit, Pb2.28Ba1.72B10O19 (PbBaBO), has been synthesized under ambient pressure. The squeezing effect of the 2∞[B10O19] bilayer structure on...

Preparation of mesoporous crack-free Sb-SnO2 xerogels through ambient-pressure drying and its application as three-dimensional electrode

2018 ◽  
Vol 86 (2) ◽  
pp. 479-492 ◽  
Author(s):  
Siqi Liu ◽  
Xiezhen Zhou ◽  
Weiqing Han ◽  
Jiansheng Li ◽  
Xiuyun Sun ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Three Dimensional ◽  
Ambient Pressure Drying

Investigation on the Yarn Squeezing Effect of Three Dimensional Full Five Directional Braided Composites

2018 ◽  
Vol 26 (1) ◽  
pp. 371-387
Author(s):  
Long Hu ◽  
Guoquan Tao ◽  
Zhenguo Liu ◽  
Yibo Wang ◽  
Jixuan Ya
Keyword(s):  
Three Dimensional ◽  
Squeezing Effect ◽  
Braided Composites

Additive Manufacturing of Porous Ceramics with Foaming Agent

2021 ◽  
pp. 1-21
Author(s):  
Zipeng Guo ◽  
Lu An ◽  
Sushil Lakshmanan ◽  
Jason Armstrong ◽  
Shenqiang Ren ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Ambient Pressure ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Cost Effective ◽  
Tensile Tests ◽  
Porous Ceramics ◽  
Foaming Agent ◽  
Printing Quality ◽  
And Control

Abstract The macro-porous ceramics has promising durability and thermal insulation performance. As porous ceramics find more and more applications across many industries, a cost-effective and scalable additive manufacturing technique for fabricating macro-porous ceramics is highly desirable. Herein, we reported a facile additive manufacturing approach to fabricate porous ceramics and control the printed porosity. Several printable ceramic inks were prepared, the foaming agent was added to generate gaseous bubbles in the ink, followed by the direct ink writing and the ambient-pressure and room-temperature drying to create the three-dimensional geometries. A set of experimental studies were performed to optimize the printing quality. The results revealed the optimal process parameters for printing the foamed ceramic ink with a high spatial resolution and fine surface quality. Varying the concentration of the foaming agent enables the controllability of the structural porosity. The maximum porosity can reach 85%, with a crack-free internal porous structure. The tensile tests showed that the printed macro-porous ceramics possessed enhanced durability with the addition of fiber. With a high-fidelity 3D printing process and the precise controllability of the porosity, we showed that the printed samples exhibited a remarkably low thermal conductivity and durable mechanical strength.

Single-component molecular conductor [Pt(dmdt)2]—a three-dimensional ambient-pressure molecular Dirac electron system

2019 ◽  
Vol 55 (23) ◽  
pp. 3327-3330 ◽  
Author(s):  
Biao Zhou ◽  
Shoji Ishibashi ◽  
Tatsuru Ishii ◽  
Takahiko Sekine ◽  
Ryosuke Takehara ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Three Dimensional ◽  
Electron System ◽  
Single Component ◽  
Nodal Lines ◽  
Molecular Conductor ◽  
System P ◽  
Dirac Electron

[Pt(dmdt)2], an air-stable single-component molecular conductor, contains massless Dirac electrons and carries Dirac nodal lines at ambient pressure.

Effects of Combustion Chamber Geometry Upon Exit Temperature Profiles

2009 ◽  
Author(s):  
Clayton Kotzer ◽  
Marc LaViolette ◽  
William Allan
Keyword(s):  
Combustion Chamber ◽  
Laser Scanning ◽  
Reference Model ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Scanning System ◽  
Geometric Deviations ◽  
Exit Temperature ◽  
Engine Operating Condition

The purpose of this research was to investigate the effects of combustion chamber geometry on exit temperature fields using an ambient pressure test rig. The apparatus contained a 120° sector of a combustion section of a Rolls Royce (previously Allison) T56-A-15 gas turbine engine. A thermocouple rake acquired high-resolution temperature measurements in the combustion chamber exit plane. Rig test conditions were set to simulate an engine operating condition of 463 km/h (250 knots) at 7620 m (25000ft) by matching the Mach number, the equivalence ratio and the Sauter mean diameter of the fuel spray. To quantify the geometric deviations of the combustion chamber specimens, which varied in service conditions, a three-dimensional laser scanning system was used. Combustion chamber geometric deviations were extracted through comparison of the scanned data to a reference model using the selected software. The relationship between combustion chamber exit temperature profile and geometric deviation was then compared. The main conclusion of this research was that small deviations from nominal dimensions in the dilution zone of the combustion chamber correlated to an increase in pattern factor. A decrease in the mixing of the products of combustion and dilution air was observed as damage in the dilution zone increased. This reduction in mixing created a more compact, higher temperature core flow. The results obtained from this research were compared to past studies.

Effects of Combustion Chamber Geometry Deviations Upon Exit Temperature Profiles for Populations With Varied Service Limitations

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
Clayton Kotzer ◽  
Marc LaViolette ◽  
William Allan ◽  
Asad Asghar
Keyword(s):  
Combustion Chamber ◽  
Temperature Profile ◽  
Laser Scanning ◽  
Reference Model ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Scanning System ◽  
Geometric Deviations ◽  
Exit Temperature

The purpose of this continuing research was to investigate the effects of combustion chamber geometry on exit temperature fields using a validated ambient pressure test rig. Rig test conditions were set to simulate an engine operating condition of 463 km/h (250 kn) at 7620 m (25,000 ft) by matching Mach number, equivalence ratio, and Sauter mean diameter of the fuel spray. Using a thermocouple rake, high resolution temperature measurements were obtained in the combustion chamber exit plane. Following the previously published procedures, a three-dimensional laser scanning system was used to quantify geometric deviations from two populations of combustion chambers. These populations differed in that one had a significantly higher allowable engine operating temperature for continuous cruise condition. Geometric deviations of both populations were compared with the reference model. The relationship between combustion chamber exit temperature profile and geometric deviation of each population was then compared. The main conclusion of this research was that the temperature profile degradation of both populations due to geometric deviations followed similar trends. These results highlighted that the difference in operating limitations of these populations did not significantly affect component performance.

scholarly journals Theoretical Studies of Furan and Thiophene Nanothreads: Structures, Cycloaddition Barriers and Activation Volumes

2021 ◽  
Author(s):  
Bo Chen ◽  
Vincent Crespi ◽  
Roald Hoffmann
Keyword(s):  
Dipole Moments ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Lone Pair ◽  
Diels Alder ◽  
Activation Barriers ◽  
High Enthalpy ◽  
Product Molecule ◽  
Onset Pressure ◽  
Volume Decrease

<p>In this theoretical study we examine several aspects of the formation, structure, and stability of the most ordered nanothreads yet made, those derived from furan and thiophene. First, we look at the enthalpic consequences and activation barriers of the first two steps of oligomerization by a Diels-Alder mechanism. The ca. 20 GPa difference in the synthetic pressures (furan lower) is explainable in terms of greater loss of aromaticity by the thiophene. Subsequent steps have understandably lower barriers. We show explicitly how pressure affects the reaction profiles, operating through the volume decrease in the transition state and onward to the product molecule. The interesting option of polymerization proceeding in one or two directions opens up the possibility of polymers with two opposing and cumulative dipole moments. The computed activation volumes are consistently more negative for likely initial furan (compared with thiophene) polymerization steps, in accord with the lower onset pressure of furan polymerization. In the second part of our study we examine the energetics of the likely polymers. Three ordered polymer structures compete in enthalpy -- a <i>syn</i> one, with all O/S on the same side, an <i>anti </i>one, S/O alternating, and a<i> syn-anti</i> isomer, with segments of four monomers repeating. The <i>syn</i> polymer, if not allowed to distort, is at high enthalpy relative to the other two. The origin of the destabilization is apparent, being S/O lone-pair repulsion, understandably greater for S than O at the 2.8/2.6Å separation. Set free, the <i>syn</i> isomers curve or arc, in two- or three-dimensional (helical) ways, whose energetics are traced in detail. The <i>syn</i> polymer can also stabilize itself by the thread twisting into zig-zag or helical enthalpic minima. Release of strain in a linear thread as the pressure is relaxed to 1 atm, with consequent thread curving, is a likely mechanism for the observed loss of crystalline order in the polymer as it is returned to ambient pressure.<br></p>

scholarly journals Two- and Three-Dimensional Superconducting Phases in the Weyl Semimetal TaP at Ambient Pressure

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 288 ◽  
Author(s):  
Maarten R. van Delft ◽  
Sergio Pezzini ◽  
Markus König ◽  
Paul Tinnemans ◽  
Nigel E. Hussey ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Grown Crystal ◽  
High Pressures ◽  
Ion Beam ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Majorana Fermion ◽  
Type I ◽  
Superconducting Transition ◽  
Superconducting Phases

The motivation to search for signatures of superconductivity in Weyl semi-metals and other topological phases lies in their potential for hosting exotic phenomena such as nonzero-momentum pairing or the Majorana fermion, a viable candidate for the ultimate realization of a scalable quantum computer. Until now, however, all known reports of superconductivity in type-I Weyl semi-metals have arisen through surface contact with a sharp tip, focused ion-beam surface treatment or the application of high pressures. Here, we demonstrate the observation of superconductivity in single crystals, even an as-grown crystal, of the Weyl semi-metal tantalum phosphide (TaP), at ambient pressure. A superconducting transition temperature, T c , varying between 1.7 and 5.3 K, is observed in different samples, both as-grown and microscopic samples processed with focused ion beam (FIB) etching. Our data show that the superconductivity present in the as-grown crystal is inhomogeneous yet three-dimensional. For samples fabricated with FIB, we observe, in addition to the three-dimensional superconductivity, a second superconducting phase that resides on the sample surface. Through measurements of the characteristic fields as a function of temperature and angle, we are able to confirm the dimensionality of the two distinct superconducting phases.

Design Space of Foil Bearings for Closed Loop Supercritical CO2 Power Cycles Based on Three-Dimensional Thermo-Hydrodynamic Analyses

2015 ◽  
Author(s):  
Daejong Kim
Keyword(s):  
Power Loss ◽  
Closed Loop ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Measured Data ◽  
Analysis Tool ◽  
Power Cycles ◽  
Foil Bearings ◽  
Flow Turbulence ◽  
Simulation Results

The closed loop Brayton cycle with super critical CO2 (S-CO2) as an operating fluid is an attractive alternative to conventional power cycles due to very high power density. Foil gas bearings using CO2 is the most promising for small S-CO2 turbomachinery but there are many problems to address; large power loss due to high flow turbulence, lack of design/analysis tool due to non-ideal gas behavior, and lack of load capacity when they are used for large systems. This paper presents high level design/analysis tool involving three-dimensional thermo-hydrodynamic analyses of radial foil bearings considering real gas effect and flow turbulence inside the film. Simulations are performed for radial foil bearing with 34.9mm in diameter lubricated with CO2 and N2 under various ambient conditions up to above 40 bar gauge pressure. The simulation results using the turbulence model still under-predict the measured data in open literature. However, the error between the prediction and measurements decreases as either speed or ambient pressure increases. In addition, general behavior of substantial increase in power loss with ambient pressure agrees with the measured data. The simulation results indicate the importance of detailed THD analysis of the foil bearings for prediction of power loss under severe turbulent condition. A conceptual layout of rotor system for 10MWe S-CO2 loop is also presented along with realistic rotor weight and bearing load. A hybrid foil bearings with diameter of 102mm is suggested for gas generator rotor, and its power losses and minimum film thicknesses at various operating conditions are presented.

Effects of Combustion Chamber Geometry Deviations Upon Exit Temperature Profiles for Populations With Varied Service Limitations

2010 ◽  
Author(s):  
Clayton Kotzer ◽  
Marc LaViolette ◽  
William Allan ◽  
Asad Asghar
Keyword(s):  
Combustion Chamber ◽  
Temperature Profile ◽  
Laser Scanning ◽  
Reference Model ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Scanning System ◽  
Geometric Deviations ◽  
Exit Temperature

The purpose of this continuing research was to investigate the effects of combustion chamber geometry on exit temperature fields using a validated ambient pressure test rig. Rig test conditions were set to simulate an engine operating condition of 463 km/h (250 knots) at 7 620 m (25,000 ft) by matching Mach number, equivalence ratio and Sauter mean diameter of the fuel spray. Using a thermocouple rake, high resolution temperature measurements were obtained in the combustion chamber exit plane. Following the previously published procedures, a three-dimensional laser scanning system was used to quantify geometric deviations from two populations of combustion chambers. These populations differed in that one had a significantly higher allowable engine operating temperature for continuous cruise condition. Geometric deviations of both populations were compared to the reference model. The relationship between combustion chamber exit temperature profile and geometric deviation of each population was then compared. The main conclusion of this research was that the temperature profile degradation of both populations due to geometric deviations followed similar trends. These results highlighted that the difference in operating limitations of these populations did not significantly affect component performance.

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