Modeling of Pretreatment and Acidogenic Fermentation of the Organic Fraction of Municipal Solid Wastes

1993 ◽  
Vol 27 (2) ◽  
pp. 193-200 ◽  
Author(s):  
M. Beccari ◽  
G. Longo ◽  
M. Majone ◽  
E. Rolle ◽  
A. Scarinci

The organic fraction of municipal solid waste represents a potential feedstock to be treated through biorefining. However, the process feasibility strongly depends on the effectiveness of a chemical pretreatment. Consequently, experimentation aimed at choosing the optimal type of reagent (alkali or acids) and optimal operating conditions was carried out. The best results were obtained using NaOH at room temperature. Solubilization data are in good agreement with a kinetics based on two competing reactions. Simulation of the overall process (pretreatment and acidogenic fermentation) taking place in two CFSTR reactors shows that an optimum ratio exists between the hydraulic residence times of the two stages of the process.

2019 ◽  
Vol 963 ◽  
pp. 773-776 ◽  
Author(s):  
Ashish Kumar ◽  
Sanket Parashar ◽  
Edward van Brunt ◽  
Shadi Sabri ◽  
Satyaki Ganguly ◽  
...  

In this paper, single pulse unclamped inductive switching (UIS) test of Wolfspeed Gen-3 10 kV, 15 A 4H-SiC MOSFETs is performed for four operating conditions at room temperature. The avalanche energy is observed to be around 7.0 J. The measured values are in good agreement with expected behavior, which may be extrapolated beyond the experimentally measured range. Failure analysis was conducted after each device failure to observe the failure locations. Avalanche parameters of SiC MOSFETs with various voltage ratings are compared. The avalanche energy of the Gen-3 10 kV, 15 A 4H-SiC MOSFETs is obtained to be superior to earlier generations of 10 kV SiC MOSFETs.


Author(s):  
S. Mahajan

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.


Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.


1988 ◽  
Vol 126 ◽  
Author(s):  
S.-Tong Lee ◽  
G. Braunstein ◽  
Samuel Chen

ABSTRACTThe defect and atomic profiles for MeV implantation of Si in GaAs were investigated using He++ channeling, TEM, and SIMS. Doses of 1–10 × 1015Si/cm2 at 1–3 MeV were used. MeV implantation at room temperature rendered only a small amount of lattice disorder in GaAs. Upon annealing at 400°C for 1 h or 800°C for 30 a, we observed a ‘defect-free’ surface region (- 1 μ for 3 MeV implant). Below this region, extensive secondary defects were formed in a band which was 0.7 μ wide and centered at 2 μ for 3 MeV implant. These defects were mostly dislocations lying in the [111] plane. SIMS depth profiles of Si implants showed the Si peak to be very close to the peak position of the defects. The experimental profiles of Si were compared to the TRIM calculation; generally good agreement existed among the peak positions.


2012 ◽  
Vol 217-219 ◽  
pp. 1497-1500 ◽  
Author(s):  
Xiao Jun Zuo ◽  
Jun Chu Li ◽  
Da Hai Liu ◽  
Long Fei Zeng

Constructing accurate constitutive equation from the optimal material constants is the basis for finite element numerical simulation. To accurately describe the creep ageing behavior of 2A12 aluminum alloy, the present work is tentatively to construct an elastic-plastic constitutive model for simulation based on the ANSYS environment. A time hardening model including two stages of primary and steady-state is physically derived firstly, and then determined by electronic creep tensile tests. The material constants within the creep constitutive equations are obtained. Furthermore, to verify the feasibility of the material model, the ANSYS based numerical scheme is established to simulate the creep tensile process by using the proposed material model. Results show that the creep constitutive equation can better describe the deformation characteristics of materials, and the numerical simulations and experimental test points are in good agreement.


2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Yan Li ◽  
Chuan-Sheng Liu ◽  
Yun-Ling Zou

AbstractZnO nano-tubes (ZNTs) have been successfully synthesized via a simple hydrothermal-etching method, and characterized by X-ray diffraction, field emission scanning electron microscopy and room temperature photoluminescence measurement. The as-synthesized ZNTs have a diameter of 500 nm, wall thickness of 20–30 nm, and length of 5 µm. Intensity of the plane (0002) diffraction peak, compared with that of plane (10$$ \bar 1 $$0) of ZNTs, is obviously lower than that of ZnO nano-rods. This phenomenon can be caused by the smaller cross section of plane (0002) of the nano-tubes compared with that of other morphologies. On basis of the morphological analysis, the formation process of nano-tubes can be proposed in two stages: hydrothermal growth and reaction etching process.


1989 ◽  
Vol 172 ◽  
Author(s):  
T. S. Aurora ◽  
D. O. Pederson ◽  
S. M. Day

AbstractLinear thermal expansion and refractive index variation have been measured in lead fluoride with a laser interferometer as a function of temperature. Data has been analyzed using the Lorentz-Lorenz relation. Molecular polarizability, band gap, variation of refractive index with density, and strain-polarizability parameter have been studied as a function of temperature. They exhibit a small variation with temperature except near the superionic phase transition where the variation appears to be more pronounced. The results are in good agreement with the published data near room temperature.


2022 ◽  
Vol 204 ◽  
pp. 111988
Author(s):  
Jacqueline Zanin Lima ◽  
Eduardo Ferreira da Silva ◽  
Carla Patinha ◽  
Nuno Durães ◽  
Eny Maria Vieira ◽  
...  

Author(s):  
Ю.В. Лубенец

Рассматривается оценка согласованности мнений экспертов при проведении экспертного опроса. Наиболее часто в качестве такой оценки применяется коэффициент конкордации Кендалла. Однако этот коэффициент не может в полной мере применяться для установления хорошей согласованности мнений экспертов, поскольку он показывает только отклонение от случаев полной несогласованности. Для устранения данного недостатка может рассматриваться альтернативный коэффициент конкордации, оценивающий близость сумм рангов альтернатив к случаю полной согласованности. Здесь дается определение этого коэффициента при наличии связанных рангов. Сложность определения заключается в том, что в этом случае наблюдается несколько случаев полной согласованности с различными суммами рангов. Определение альтернативного коэффициента конкордации при наличии связанных рангов проводится в два этапа. Сначала вводится его определение для упорядоченных таблиц специального вида и показывается его совпадение с коэффициентом конкордации Кендалла в этом случае. После дается определение альтернативного коэффициента конкордации в общем случае и показывается более простая формула его вычисления. Далее приводятся некоторые примеры сравнений значений рассматриваемых коэффициентов конкордации, их статистических характеристик и гистограмм The article considers evaluation of expert opinion consistency when conducting an expert survey. The most commonly used score is Kendall's coefficient of concordance. However, this coefficient cannot be fully applied to establish good agreement of expert opinions, as it only shows deviations from cases of complete inconsistency. To eliminate this drawback, an alternative concordance coefficient can be considered, which estimates the proximity of the sums of the ranks of the alternatives to the case of complete consistency. The article gives the definition of this coefficient in the presence of connected ranks. The difficulty of this definition lies in the fact that in this case there are several cases of complete consistency with different sums of ranks. Definition of the alternative coefficient of concordance in the presence of tied ranks is carried out in two stages. First, its definition for ordered tables of a special kind is introduced and its coincidence with Kendall's coefficient of concordance in this case is shown. After that, the definition of the alternative coefficient of concordance in the general case is given and a simpler formula for its calculation is shown. Below are some examples of comparisons of the values of the considered concordance coefficients, their statistical characteristics, and histograms


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