scholarly journals New Definition of Ultrafine Particles in Mine Paste and Its Relationship with Rheological Properties

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Jincheng Xie ◽  
Dengpan Qiao ◽  
Runsheng Han ◽  
Tao Deng ◽  
Jun Wang
Keyword(s):  
Rheological Properties ◽  
Ultrafine Particles ◽  
Size Range ◽  
Engineering Practice ◽  
Mathematical Significance ◽  
Analysis Model ◽  
Mine Backfill ◽  
Coarse Aggregates ◽  
Geometric Size ◽  
Definition Of

Mine backfill paste is generally composed of tailings and coarse aggregates. In engineering practice, the definitions in fill material classification are vague. In this paper, the size range of ultrafine particles is defined by the Stokes sedimentation test and hydraulic coarseness method. The size range of ultrafine particles is affected not only by the geometric size of the particles but also by the physical characteristics of the particles themselves. This definition has more comprehensive considerations and stricter physical and mathematical significance than the traditional definition of ultrafine particles based only on size. There is a strong correlation between ultrafine particles in fill materials and the rheological properties of the mine backfill paste. In this study, through experiments and correlation analysis, it was found that the content of ultrafine particles is positively correlated with the plastic viscosity of the mine backfill paste, and its growth range is exponential. The coarse aggregate content is positively correlated with the yield stress of the mine backfill paste. A regression analysis model was established for the rheological properties of mine backfill paste. The model has few factors and high correlation, so it can simply and efficiently predict the rheological properties of mine backfill paste and guide engineering practice.

scholarly journals Are ultra-diffuse galaxies Milky Way-sized?

2020 ◽  
Vol 633 ◽  
pp. L3 ◽  
Author(s):  
Nushkia Chamba ◽  
Ignacio Trujillo ◽  
Johan H. Knapen
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Size Range ◽  
Mass Density ◽  
Effective Radius ◽  
Density Profiles ◽  
Gas Density ◽  
Undesirable Consequence ◽  
Definition Of ◽  
Density Threshold

Now almost 70 years since its introduction, the effective or half-light radius has become a very popular choice for characterising galaxy size. However, the effective radius measures the concentration of light within galaxies and thus does not capture our intuitive definition of size which is related to the edge or boundary of objects. For this reason, we aim to demonstrate the undesirable consequence of using the effective radius to draw conclusions about the nature of faint ultra-diffuse galaxies (UDGs) when compared to dwarfs and Milky Way-like galaxies. Instead of the effective radius, we use a measure of galaxy size based on the location of the gas density threshold required for star formation. Compared to the effective radius, this physically motivated definition places the sizes much closer to the boundary of a galaxy. Therefore, considering the sizes and stellar mass density profiles of UDGs and regular dwarfs, we find that the UDGs have sizes that are within the size range of dwarfs. We also show that currently known UDGs do not have sizes comparable to Milky Way-like objects. We find that, on average, UDGs are ten times smaller in extension than Milky Way-like galaxies. These results show that the use of size estimators sensitive to the concentration of light can lead to misleading results.

Study on Energy Consumption Analysis Method of Distributed Cryogenic Separation System

2013 ◽  
Vol 732-733 ◽  
pp. 52-56
Author(s):  
Zhi Guo Wang ◽  
Lei Zhang ◽  
Chai Ling Yin
Keyword(s):  
Energy Use ◽  
Exergy Analysis ◽  
Waste Heat ◽  
Engineering Practice ◽  
Analysis Method ◽  
Analysis Model ◽  
Two Stage ◽  
Separation Plant ◽  
Flow Energy ◽  
Saving Effect

Cryogenic separation method is the main method to recycle NGL (Natural Gas Liquid). Oilfield two-stage expansion NGL cryogenic separation plant is a complex system composed of varieties of material flow, energy flow and equipments, is a typical distributed energy use system composed of three parts, energy supply, energy use and waste heat recovery. In this paper, according to the process characteristics of two-stage expansion cryogenic separation plant, three-box analysis method was used, the system was compartmentalized into six subsystems, represented the exergy analysis model of system—unit—equipment, given the specific analysis process and the assessment rules for the NGL system. Using the practical operational data, the writers conduct the exergy analysis on the operational working condition of Daqing oilfield NGL system. Based on the calculation results, this paper raises some proposals to improve the operational efficiency, and achieved a good energy saving effect in engineering practice.

Quantification of major and trace elements contained in aircraft JET A-1 fuel by in-vacuum PIXE analysis

2021 ◽  
pp. 1950016
Author(s):  
Katsumi Saitoh ◽  
Akihiro Fushimi ◽  
Nobuyuki Takegawa ◽  
Koichiro Sera
Keyword(s):  
Ultrafine Particles ◽  
Size Range ◽  
Concentration Level ◽  
Treatment Method ◽  
Major And Trace Elements ◽  
Jet Fuel ◽  
Jet Engines ◽  
Pixe Analysis ◽  
Measurement Results ◽  
Exhaust Particles

To characterize the chemical composition of aircraft exhaust particles, we developed a treatment method of jet fuel for an elemental analysis by an in-vacuum PIXE system. Eleven elements (Si, S, Cl, K, Ca, Cr, Fe, Ni, Cu, Zn, and Pb) were identified from each sample. The concentrations of S from five JET A-1 fuel samples collected on different days ranged from 30.4 to 440 wt.-ppm. The concentration level of S agreed well with the measurement results obtained by an in-air PIXE analysis, which we have previously performed to determine the major content elements and their concentration levels. Nine elements out of the identified 11 elements (Si, Cl, K, Ca, Cr, Ni, Cu, Zn, and Pb), which were not detected by the in-air PIXE analysis, were detected in all the JET A-1 fuel samples measured. Among these elements, Si, Ni, Cu, Zn, and Pb were found to be the major components. It is suggested that particles emitted from aircraft jet engines, which are generally in the size range smaller than 100 nm (ultrafine particles: UFPs), may contain Si, Ni, Cu, Zn, and Pb. These findings provide useful insights into the source apportionment of UFPs in and around airports.

scholarly journals The parametric restrictions of the Gardner and Eberhart diallel analysis model: heterosis analysis

2000 ◽  
Vol 23 (4) ◽  
pp. 869-875 ◽  
Author(s):  
José Marcelo Soriano Viana
Keyword(s):  
Statistical Models ◽  
Combining Ability ◽  
Genetic Parameter ◽  
Diallel Analysis ◽  
Sums Of Squares ◽  
Analysis Model ◽  
Model Method ◽  
Combining Ability Analysis ◽  
Definition Of ◽  
Parameter Values

It was studied the parametric restrictions of the diallel analysis model of Griffing, method 2 (parents and F1 generations) and model 1 (fixed), in order to address the questions: i) does the statistical model need to be restricted? ii) do the restrictions satisfy the genetic parameter values? and iii) do they make the analysis and interpretation easier? Objectively, these questions can be answered as: i) yes, ii) not all of them, and iii) the analysis is easier, but the interpretation is the same as in the model with restrictions that satisfy the parameter values. The main conclusions were that: the statistical models for combining ability analysis are necessarily restricted; in the Griffing model (method 2, model 1), the restrictions relative to the specific combining ability (SCA) effects, <img src="http:/img/fbpe/gmb/v23n4/6246s1.gif" align="absmiddle"> and <img src="http:/img/fbpe/gmb/v23n4/6246s2.gif" align="absmiddle"> for all j, do not satisfy the parametric values, and the same inferences should be established from the analyses using the model with restrictions that satisfy the parametric values of SCA effects and that suggested by Griffing. A consequence of the restrictions of the Griffing model is to allow the definition of formulas for estimating the effects, their variances and the variances of contrasts of effects, as well as for calculating orthogonal sums of squares.

Ultrafine particles in the cabin of a waiting commercial airliner at Tianjin International Airport, China

2017 ◽  
Vol 27 (9) ◽  
pp. 1247-1258 ◽  
Author(s):  
Jianlin Ren ◽  
Junjie Liu ◽  
Xiaodong Cao ◽  
Fei Li ◽  
Jianmin Li
Keyword(s):  
Particle Size ◽  
Ultrafine Particles ◽  
Size Range ◽  
Environmental Control ◽  
Particle Dynamic ◽  
Ground Vehicles ◽  
Flight Delays ◽  
Penetration Factor ◽  
International Airport ◽  
Outdoor Concentration

Passengers and crew on board of commercial airliners often spend extra time in the cabin waiting for departure due to flight delays. During the waiting period, a large amount of ambient ultrafine particles (UFPs) may penetrate into the aircraft cabin through the environmental control system (ECS) and ground air-conditioning cart (GAC). However, limited data are available for human exposure, in waiting commercial airliners, to freshly emitted UFPs from the exhaust of ground vehicles and airliners. To address this issue, we measured the ambient and in-cabin particle number concentrations and particle size distributions (PSDs) simultaneously in an MD-82 airliner parked at Tianjin International Airport, China. When air was supplied to the cabin by GAC, particle counts variation outdoors caused in-cabin variation with a 1–2 min delay. The in-cabin and ambient PSDs ranged from 15 to 600 nm were bimodal, with peaks at 30–40 and 70–90 nm. The GAC and ECS removed 1–73% particles in the size range of 15–100 nm and 30–47% in the size range of 100–600 nm. The relationship between the penetration factor and particle size was an inverted U-curve. An improved particle dynamic model from this study was used to calculate the time-dependent in-cabin UFPs concentrations with dramatic changes in outdoor concentration.

Significance Analysis on the Affecting Factors of Basic Reserve Fund in Power Engineering Based on FAT

2014 ◽  
Vol 584-586 ◽  
pp. 2333-2338
Author(s):  
Xue Liang Hou ◽  
Yue Li ◽  
Ying Rong Yang
Keyword(s):  
Research Result ◽  
Fault Tree Analysis ◽  
Reference Value ◽  
Power Engineering ◽  
Utilization Efficiency ◽  
Engineering Practice ◽  
Affecting Factors ◽  
Analysis Model ◽  
Significance Analysis ◽  
Reserve Fund

Basic reserve fund is a part of the power engineering total cost. Reducing its quantity can obviously increase the utilization efficiency of engineering cost. But how can reduce the quantity of basic reserve fund, we can start from its affecting factors. To this, for the affecting factors of basic reserve fund, this paper constructed the significance analysis model about affecting factors based on its actual application situation and Fault Tree Analysis (FAT). Finally, we got the degree and prior about affecting factors of basic reserve fund. Thereby the empirical research result provided a theory reference value which can control the quantity of basic reserve fund in the engineering practice.

Negative grey relational model and measurement of the reverse incentive effect of fields medal

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sifeng Liu
Keyword(s):  
Grey Relational Analysis ◽  
Research Output ◽  
Analysis Model ◽  
Content Type ◽  
Relational Analysis ◽  
Fields Medal ◽  
Definition Of ◽  
Grey Relational ◽  
Analysis Models ◽  
The Relationship

PurposeThe purpose of this paper is to construct some negative grey relational analysis models to measure the relationship between reverse sequences.Design/methodology/approachThe definition of reverse sequence has been given at first based on analysis of relative position and change trend of sequences. Then, several different negative grey relational analysis models, such as the negative grey similarity relational analysis model, the negative grey absolute relational analysis model, the negative grey relative relational analysis model, the negative grey comprehensive relational analysis model and the negative Deng’s grey relational analysis model have been put forward based on the corresponding common grey relational analysis models. The properties of the new models have been studied.FindingsThe negative grey relational analysis models proposed in this paper can solve the problem of relationship measurement of reverse sequences effectively. All the new negative grey relational degree satisfying the requirements of normalization and reversibility.Practical implicationsThe proposed negative grey relational analysis models can be used to measure the relationship between reverse sequences. As a living example, the reverse incentive effect of winning Fields Medal on the research output of winners is measured based on the research output data of the medalists and the contenders using the proposed negative grey relational analysis model.Originality/valueThe definition of reverse sequence and the negative grey similarity relational analysis model, the negative grey absolute relational analysis model, the negative grey relative relational analysis model, the negative grey comprehensive relational analysis model and the negative Deng’s grey relational analysis model are first proposed in this paper.

scholarly journals Study on the Fracture Law of Inclined Hard Roof and Surrounding Rock Control of Mining Roadway in Longwall Mining Face

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5344
Author(s):  
Feng Cui ◽  
Shuai Dong ◽  
Xingping Lai ◽  
Jianqiang Chen ◽  
Chong Jia ◽  
...  
Keyword(s):  
Energy Release ◽  
Longwall Mining ◽  
Coal Pillar ◽  
High Energy ◽  
Mechanical Analysis ◽  
Engineering Practice ◽  
Analysis Model ◽  
Hard Roof ◽  
Working Face ◽  
The Stability

In the inclination direction, the fracture law of a longwall face roof is very important for roadway control. Based on the W1123 working face mining of Kuangou coal mine, the roof structure, stress and energy characteristics of W1123 were studied by using mechanical analysis, model testing and engineering practice. The results show that when the width of W1123 is less than 162 m, the roof forms a rock beam structure in the inclined direction, the floor pressure is lower, the energy and frequency of microseismic (MS) events are at a low level, and the stability of the section coal pillar is better. When the width of W1123 increases to 172 m, the roof breaks along the inclined direction, forming a double-hinged structure, the floor pressure is increased, and the frequency and energy of MS events also increases. The roof gathers elastic energy release, and combined with the MS energy release speed it can be considered that the stability of the section coal pillar is better. As the width of W1123 increases to 184 m, the roof in the inclined direction breaks again, forming a multi-hinged stress arch structure, and the floor pressure increases again. MS high-energy events occur frequently, and are not conducive to the stability of the section coal pillar. Finally, through engineering practice we verified the stability of the section coal pillar when the width of W1123 was 172 m, which provides a basis for determining the width of the working face and section coal pillar under similar conditions.

scholarly journals Finite Element Failure Analysis of GFRP Laminates in Plate-Cone Reticulated Shell

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xing Wang ◽  
Yu Jiang ◽  
Yonghui Huang ◽  
Yue Huang ◽  
Fan Wang
Keyword(s):  
Failure Analysis ◽  
Composite Laminates ◽  
Strength Criterion ◽  
Laminated Plates ◽  
Engineering Practice ◽  
Analysis Model ◽  
Ansys Software ◽  
Strength Failure ◽  
New Type ◽  
Element Failure

Plate-cone reticulated shell is a new type of spatial structures with good mechanical behavior, technical economy, and architectural appearance. In this paper, using ANSYS software, the strength failure analysis model of composite laminates is established in cooperation with the Strength Criterion of Hoffman. The effects of layer number, laying direction, and thickness of laminates on the ultimate strength of laminates are studied by detailed parametric analysis, which provides a theoretical basis for the design of composite plate-cone reticulated shell and GFRP laminated plates. Some important conclusions are obtained and can be applied to engineering practice.

Study on Kinematics Sensitivities of Folder Mechanism with Clearance

2011 ◽  
Vol 121-126 ◽  
pp. 4764-4769
Author(s):  
Ying Cai Yuan ◽  
Yan Li ◽  
Yi Ming Wang ◽  
Qiang Guo
Keyword(s):  
Sensitivity Analysis ◽  
High Velocity ◽  
High Speed ◽  
Development Trend ◽  
Matrix Analysis ◽  
Analysis Model ◽  
Design Variables ◽  
The Matrix ◽  
The Stability ◽  
Definition Of

High velocity and stability are the development trend and inevitable requirement, but the clearance would make the stability of mechanical system deceased, especially in high speed. To the folder mechanism with clearances in high velocity, combined with the definition of sensitivity and the kinematics analysis, the kinematics sensitivity analysis model is derived by the matrix analysis method. Through the sensitivity analysis model, it can be easy to get the relationship of the design variables and the mechanism’s robustness, which provides the base to design the folder mechanism in high velocity.

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