In this paper, the temperature-dependent vibration damping in c/Sic fiber-reinforced ceramic-matrix composites (cMcs) with different fiber preforms under different vibration frequencies is investigated. A micromechani...
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In this paper, the temperature-dependent vibration damping in c/Sic fiber-reinforced ceramic-matrix composites (cMcs) with different fiber preforms under different vibration frequencies is investigated. A micromechanical temperature-dependent vibration damping model is developed to establish the relationship between composite damping, material properties, internal damage mechanisms, and temperature. The effects of fiber volume, matrix crack spacing, and interface properties on temperature-dependent composite vibration damping of cMcs and interface damage are analyzed. The experimental temperature-dependent composite damping of 2D and 3D c/Siccomposites is predicted for different loading frequencies. The damping of the c/Siccomposite increases with temperature to the peak value and then decreases with temperature. When the vibration frequency increases from f = 1 to 10 Hz, the peak value of composite damping and corresponding temperature both decrease due to the decrease of interface debonding and slip range, and the damping of 2D c/Sic is much higher than that of 3D c/Sic at temperature range from room temperature to 400 degrees c. When the fiber volume and interface debonding energy increase, the peak value of composite damping and the corresponding temperature decreases, mainly attributed to the decrease of interface debonding and slip range.
compilers use a variety of techniques to optimize and transform loops. However, many of these optimizations do not work when the loop is irreducible. Node splitting techniques transform irreducible loops into reducibl...
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compilers use a variety of techniques to optimize and transform loops. However, many of these optimizations do not work when the loop is irreducible. Node splitting techniques transform irreducible loops into reducible loops, but many real-world compilers choose to leave them unoptimized. This article describes an empirical study of irreducibility in current versions of open-source software, and then compares them with older versions. We also study machine-generated ccode from a number of software tools. We find that irreducibility is extremely rare, and is becoming less common with time. We conclude that leaving irreducible loops unoptimized is a perfectly feasible future-proof option due to the rarity of its occurrence in non-trivial software. copyright (c) 2011 John Wiley & Sons, Ltd.
Transpiration cooling system in hypersonic vehicles still remains a challenge due to the limitations of observing permeability and microstructure evolution of porous medium filled with coolant. To tackle this problem,...
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Transpiration cooling system in hypersonic vehicles still remains a challenge due to the limitations of observing permeability and microstructure evolution of porous medium filled with coolant. To tackle this problem, a novel compression-permeation device is designed with high-resolution X-ray tomography system, and then an investigation on permeability evolution mechanism of a c/Sic porous ceramic under pressure is performed using insitu X-ray imaging and the compression-permeation device. The experimental results indicate that the pore-space fluid flow is displayed in terms of three-dimensional streamlines, making the permeability mechanism clear. Meanwhile the porosity along the thickness of ceramic under pressure has been obtained by synchrotron tomography testing, and it is also verified that the porosity of c/Sicceramic fabricated in our research group is basically uniform (>95.4%) along the thickness. Furthermore, we have found the evolution rule for permeability of porous ceramic with water, which depends on the variation of its microstructure under different loads.
The mechanism and effect of c/N ratios on the aerobic granules simultaneous nitrification, denitrification and phosphorus removal (SNDPR) system are still unclear. The reactor performance and microbial community dynam...
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The mechanism and effect of c/N ratios on the aerobic granules simultaneous nitrification, denitrification and phosphorus removal (SNDPR) system are still unclear. The reactor performance and microbial community dynamics of the system were investigated under variable c/N ratios (20, 10 and 5). The cOD, TP and NH4+-N removal remained unaffected with variable c/N ratios. The decreased c/N ratio of five strongly influenced the nitrogen removal. Further investigations revealed that candidatus_Accumulibacter, Acinetobacter, candidatus_competibacter were the predominant genera. classification of key groups involved in nitrogen and phosphorus removal indicated the lowest c/N ratio resulting in a large microbial community shift. This study might contribute to the application of SNDPR system for the treatment of wastewater. Different c/N ratios led to shift on the microbial community and the dominant was phosphorus-accumulating bacteria. The nitrogen removal efficiency decreased while the removal of cOD, TP and NH4+-N remained remarkable with the decreased c/N ratios.
AbstractA micro‐kernel that supports concurrent execution of c procedures within a single user process is described. A micro‐kernel provides only four primitives, which have been used to build a number of higher‐le...
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AbstractA micro‐kernel that supports concurrent execution of c procedures within a single user process is described. A micro‐kernel provides only four primitives, which have been used to build a number of higher‐level abstractions, including support for distributed processing. The micro‐kernel differs from other efforts in that it is small and efficient, it is written entirely as a non‐privileged user program, and it provides fine‐grained unpredictable interleaving o
The solar radio spectra of the gyro-synchrotron radiation without absorption from mildly relativistic non-thermal electron have been presented using the model with the spherical symmetric *** spectra have the followin...
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The solar radio spectra of the gyro-synchrotron radiation without absorption from mildly relativistic non-thermal electron have been presented using the model with the spherical symmetric *** spectra have the following features: (i) Twists and turns of the spectra,which appear at the joint between the medium and high frequencies,(ii) Flux density drop at the lower *** if there are no absorption in the radio sources,flux density drop at the lower frequencies is still present because of magnetic nonhomogeneity.(iii) These theoretical spectra belong to c *** provides us a new interpretation for the observed solar burst c type spectra.
Non-specific phospholipase c (NPc) is involved in plant growth, development and stress responses. To elucidate the mechanism by which NPcs mediate cellular functions, here we show that NPc4 is S-acylated at the c term...
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Non-specific phospholipase c (NPc) is involved in plant growth, development and stress responses. To elucidate the mechanism by which NPcs mediate cellular functions, here we show that NPc4 is S-acylated at the c terminus and that acylation determines its plasma membrane (PM) association and function. The acylation of NPc4 was detected using NPc4 isolated from Arabidopsis and reconstituted in vitro. The c-terminal cys-533 was identified as the S-acylation residue, and the mutation of cys-533 to Ala-533 in NPc4 (NPc4(c533A)) led to the loss of S-acylation and membrane association of NPc4. The knockout of NPc4 impeded the phosphate deficiency-induced decrease of the phosphosphingolipid glycosyl inositol phosphoryl ceramide (GIPc), but introducing NPc4(c533A) to npc4-1 failed to complement this defect, thereby supporting the hypothesis that the non-acylated NPc4(c533A) fails to hydrolyze GIPc during phosphate deprivation. Moreover, NPc4(c533A) failed to complement the primary root growth in npc4-1 under stress. In addition, NPc4 in Brassica napus was S-acylated and mutation of the S-acylating cysteine residue of ***4 led to the loss of S-acylation and its membrane association. Together, our results reveal that S-acylation of NPc4 in the c terminus is conserved and required for its membrane association, phosphosphingolipid hydrolysis and function in plant stress responses.
ZrB2 particles were preset to the c-AlSi interface to improve oxidation resistance of c/c preform and adjust the microstructure of the interpenetrated c/c-AlSi composite prepared through pressure infiltration of eutec...
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ZrB2 particles were preset to the c-AlSi interface to improve oxidation resistance of c/c preform and adjust the microstructure of the interpenetrated c/c-AlSi composite prepared through pressure infiltration of eutectic AlSi into a fiber fabric based porous c/c skeleton. Micro-morphology investigations suggested that the AlSi textures were changed from dendritic to petals-like state, and the nano to micro-scale ZrB2 particles were dispersed into AlSi and affected the distribution of Al and Si nearby carbon. Tests demonstrated that c/c-AlSi have slight lower density and thermal expansion coefficient, and higher original compressive strength, while c/c-ZrB2-AlSi composites presented an outstanding strength retention rate after thermal shock. Fracture and micro-morphology indicated that the influence of the preset ZrB2 to the interface of carbon and alloy greatly affected the generation and propagation of cracks, which determined the diverse compression behaviors of the composites before and after thermal shock.
The use of ozone in food processing has become an eco-friendly, cost-effective way to manage insect pests and improve grain quality. The present study examined the efficacy of different ozone concentrations (500-1000 ...
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The use of ozone in food processing has become an eco-friendly, cost-effective way to manage insect pests and improve grain quality. The present study examined the efficacy of different ozone concentrations (500-1000 ppm), exposure time (2-6 h), and grain moisture content (11-15%, wb) on mortality of different developing stages (egg, larvae, and pupae) and adult of callosobruchus maculatus. Treated Mung bean was also analyzed for in-vitro protein digestibility (IVPD), grain hardness, and germination rate. A comparison between untreated (control) and treated mung bean samples at optimized conditions was conducted to determine the influence of ozone on proximate and mineral analysis, thermal and pasting properties. c. maculatus pupae and adults were least susceptible to ozonation, with mortality rates of 11.11 and 13.04-100%, respectively. In the optimal condition of 11.17% grain moisture content, 1000 ppm ozone concentration, and 2 h exposure time, mortality of different life stages (egg, larvae, pupae, and adults) of c. maculatus was calculated as 104.07%, 90.15%, 86.82%, and 83.55%, respectively. The corresponding values of IVPD, hardness, and grain germination were 67.85%, 57.43 N, and 87.74%, respectively. There was a noticeable decrease in protein, fat, and mineral content in ozone-treated mung bean compared to the control. Furthermore, enhancement in thermal and pasting properties of ozonated mung beans suggest that ozone can be utilized to develop high quality grain products' while ensuring their safety.
Transpiration cooling has been gradually regarded as one of the most efficient and potential thermal protection technologies for the high temperature hot-end components of future hypersonic vehicle. The cooling perfor...
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Transpiration cooling has been gradually regarded as one of the most efficient and potential thermal protection technologies for the high temperature hot-end components of future hypersonic vehicle. The cooling perfor-mance of this technology profoundly depends on the properties of porous medium. This paper exhibits a novel c/ Sic porous ceramic with controllable properties adjusted by molding pressure and carbon fiber content in the grinding-mold pressing-sintering process, and investigates the transpiration cooling performance using this ceramic with liquid water. Molding pressure improves from 50 MPa to 100 MPa, the compressive strength has increased by 52.9% and 67.9%, and the permeability decreases about 38% and 39.5% respectively corresponding to fiber content of 6% and 10%. The surface temperatures and back-side temperatures of porous ceramic with the largest molding pressure reaches the highest due to the lowest porosity which can reduce the heat exchange area between cooling water and porous ceramic skeleton. This novel porous ceramic with controllable characteristics can optimize the design of the transpiration cooling system.
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