scholarly journals Effects of Metamorphic Degree of Coal on Coal Dust Wettability and Dust-Suppression Efficiency via Spraying

2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Pengfei Wang ◽  
Han Han ◽  
Ronghua Liu ◽  
Yongjun Li ◽  
Xuanhao Tan
Keyword(s):  
Coal Dust ◽  
Great Influence ◽  
Dust Suppression ◽  
Coal Quality ◽  
Factors Affecting ◽  
Suppression Efficiency ◽  
Underground Coal Mines ◽  
The Difference ◽  
Highly Correlated ◽  
And Control

Currently, spraying is a main means for dust prevention and control in underground coal mines. The dust-suppression efficiency via spraying is highly correlated with the wettability of coal dusts. There are many factors affecting the wettability of coal dust, among which coal’s metamorphic degree has great influence. In order to gain in-depth knowledge of the effects of coal metamorphic degree on coal dust wettability and the dust-suppression efficiency via spraying, 6 coal dust samples with different metamorphic degrees were collected and used in the study. In the experiments, the microproperties, wetting performance, and dust-suppression efficiency via spraying were measured. According to the experimental results of coal’s microproperties, with the improvement of metamorphic degree, the content of hydrophilic oxygen-containing functional groups on the surface, the surface roughness, the specific surface area, and the interpore diameter all decreased. In addition, as coal’s metamorphic degree was enhanced from lignite to meager-lean coal, the wettability of the coal dust dropped. On the other hand, as the metamorphic degree of coal quality continued to be improved to anthracite, the wettability of the coal dust increased instead. The measured results revealed that the dust-suppression efficiency via spraying was highly correlated with the wettability of coal dust. The coal dust with better wettability exhibited higher dust-suppression efficiency via spraying. With the increase of water-supply pressure, the effect of coal dust wettability on the dust-suppression efficiency via spraying was weakened, and the difference of dust-suppression efficiency among different coal dust samples was narrowed.

scholarly journals Research on the Difference Mechanism of High Voltage Circuit Breaker’s Opening/Closing Coil Current

2021 ◽  
Vol 261 ◽  
pp. 01014
Author(s):  
Yi Su ◽  
Yufeng Lu ◽  
Lei Zhang ◽  
Xiajin Rao
Keyword(s):  
High Voltage ◽  
Circuit Breaker ◽  
Structural Difference ◽  
Circuit Breakers ◽  
Coil Current ◽  
Factors Affecting ◽  
The Operating Mechanism ◽  
The Difference ◽  
Protection And Control ◽  
And Control

High voltage circuit breakers are important protection and control equipment for the power grid. The defects and faults of the circuit breaker seriously affect the safety and stability of the power system. As the key component of the operating mechanism of the circuit breaker, the opening/closing coils contain a large amount of information about the operating status of the mechanism. In order to investigate the cause of the difference in the current waveforms, this paper analyzes the factors affecting the circuit breaker opening/closing coil current based on the actual high voltage circuit breaker, and distinguishes the characteristics of the current caused by the environmental difference and Structural difference. At the same time, the characteristics of coil current changes under four different types of mechanism defects are analyzed. These results lay the foundation for status evaluation of high voltage circuit breakers based on opening/closing coil current.

scholarly journals Comparison of the Performance of Photovoltaic Power Generation-Consumption System with Push-Pull Converter under the Effect of Five Different Types of Controllers

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Hilmi Zenk
Keyword(s):  
Dynamic System ◽  
System Modeling ◽  
Energy Generation ◽  
Dc Motor ◽  
Reference Voltage ◽  
Factors Affecting ◽  
Dc Voltage ◽  
System Output ◽  
The Difference ◽  
And Control

In this study, a dynamic system has been modeled to efficiently use a photovoltaic generation and control system (PVGCS) for driving of a medium power off-grid electric machine. The measures have been taken to respond to three different disturbing factors in this system. First, the photovoltaic panels selected for energy generation have a variable solar radiation effect. Second, the DC motor load at the system output is assumed to have a variable torque. Third, a variable reference voltage, which is determined even in the case of time-varying energy generation and consumption of the system, is followed with minimum error. For this purpose, a push-pull converter has been chosen as a highly flexible structure since it is predicted that it can provide stable and effective variable DC voltage at increasing and decreasing level required for DC motor. The control of the DC voltage at different levels to be provided by the push-pull converter is performed by PI, fuzzy logic, fuzzy-tuned PI, 2-DOF PI, and fractional PID logic whose coefficients are selected by appropriate methods, respectively. The system efficiency and stability under the influence of these five different advanced controllers are compared. In the case of two disturbing factors affecting the system, the difference values (errors) of the voltage generated by each selected controller with the reference voltage are determined comparatively. The studies were carried out by using dynamic system modeling in MATLAB-SIMULINK software. In addition, the results of this study proved which type of controllers is more successful in controlling systems with the second order and more instability factors and which of them responds to sudden changes in errors more quickly.

Evaluation of the coal dust suppression efficiency of different surfactants: A factorial experiment

2020 ◽  
Vol 595 ◽  
pp. 124686 ◽  
Author(s):  
Ping Chang ◽  
Zidong Zhao ◽  
Guang Xu ◽  
Apurna Ghosh ◽  
Jinxin Huang ◽  
...  
Keyword(s):  
Coal Dust ◽  
Factorial Experiment ◽  
Dust Suppression ◽  
Suppression Efficiency

scholarly journals Evaluating the Impact of Building Information Modeling (BIM) on Mass House Building Projects

Buildings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 35 ◽  
Author(s):  
Hadi Sarvari ◽  
Daniel W. M. Chan ◽  
Mansooreh Rakhshanifar ◽  
Nerija Banaitiene ◽  
Audrius Banaitis
Keyword(s):  
Building Information Modeling ◽  
Great Influence ◽  
Information Modeling ◽  
Survey Method ◽  
Building Projects ◽  
Factors Affecting ◽  
Building Information ◽  
The Difference ◽  
The Impact ◽  
Whole Life Cycle

This paper aims to identify and investigate the factors affecting the goals of mass-housing building projects due to the use of building information modeling (BIM). A descriptive-survey method was used to collect necessary data. Fifty respondents from the target sectors and experts in the field of modeling building information participated in self-selection survey. The tools of collecting data included three questionnaires regarding three phases of construction work: pre-construction, during construction and post-construction, which were developed based on the three indices of cost, time and quality. The face, content and construct validity of the questionnaires were confirmed after several rounds of testing. The reliability coefficient of the pre-construction, during the construction and post-construction questionnaires were 0.923, 0.917 and 0.876, respectively. The results show that the F-statistic is significant for the difference between the three groups (pre-construction, during construction and post-construction) at the 0.01 level. The results confirmed that BIM has a great influence on a project in terms of meeting time, cost and quality objectives through the whole life cycle of a construction project: during pre-construction, construction, and post-construction stages.

Influence of particle diameter on the wettability of coal dust and the dust suppression efficiency via spraying

2019 ◽  
Vol 132 ◽  
pp. 189-199 ◽  
Author(s):  
Pengfei Wang ◽  
Xuanhao Tan ◽  
Lianyang Zhang ◽  
Yongjun Li ◽  
Ronghua Liu
Keyword(s):  
Coal Dust ◽  
Particle Diameter ◽  
Dust Suppression ◽  
Suppression Efficiency

scholarly journals 4-6 KLASIŲ MOKSLEIVIŲ SUVOKIAMOS MOKYMOSI KONTROLĖS YPATUMAI

Psichologija ◽  
2000 ◽  
Vol 22 ◽  
pp. 64-73
Author(s):  
Roma Šimulionienė
Keyword(s):  
School Performance ◽  
School System ◽  
School Success ◽  
Fourth Graders ◽  
Control Beliefs ◽  
Factors Affecting ◽  
School Grades ◽  
Highly Correlated ◽  
Children's Beliefs ◽  
And Control

Pačia bendriausia prasme suvokiama kontrolė yra apibrėžiama kaip naivūs pačių individų susikuriami priežastiniai modeliai. Juose atsispindi, kaip suvokiamos norimų ir nenorimų įvykių priežastys, pačių individų vaidmuo jiems patiriant sėkmę ar nesėkmę, taip pat kitų žmonių, institucijų ar socialinių sistemų reagavimas (E. A. Skinner, 1995).Savo darbe vadovavomės suvokiamos kontrolės koncepcija (E. A. Skinner, M. Chapman, P. B. Baltes, 1988), kuria siekiama diferencijuoti ir integruoti keturių, jos autorių nuomone, pagrindinių suvokiamos kontrolės teorijų konstruktus: kontrolės lokusą, išmoktą bejėgiškumą, kauzalinę atribuciją ir aš efektyvumą. Visi šie konstruktai įeina į kompetencijos sistemą, kurios funkcija yra reguliuoti ir interpretuoti tikslingas interakcijas su aplinka (J. P. Connell, J. G. Wellborn, 1991; E. A. Skinner, 1995). AGENCY, CONTROL, AND MEANS-ENDS ABOUT SCHOOL PERFORMANCE IN LITHUANIAN CHILDREN (GRADES 4-6)Roma Šimulionienė Summary This study examined beliefs about factors affecting school performance and about self-agency and control in Lithuanian children (grades 4-6, N = 379). Results revealed much intercultural convergence with the samples from other countries in children’s beliefs about the importance of effort, ability, luck and unknown factors as causes of school performance. The only difference we found was in the beliefs about the importance of teachers. Their ratings were the lowest. But at the same time the ratings of the accessability of teacher as a mean of school success were high (second after effort). The agency and control beliefs were moderately and highly correlated with school grades (r = 0,29-0,57). The fourth graders showed higher agency and control beliefs and the lowest correlations with school performance. These findings are interpreted as beeing affected by positive changes in Lithuanian school system.

Analysis of the horizontal structure of a measurement and control geodetic network based on entropy

2013 ◽  
Vol 62 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Maria Mrówczyńska
Keyword(s):  
Geodetic Network ◽  
The State ◽  
Observation System ◽  
Optimum Number ◽  
Optimum Structure ◽  
Horizontal Structure ◽  
The Difference ◽  
And Control ◽  
Measurement And Control ◽  
Horizontal Displacements

Abstract The paper attempts to determine an optimum structure of a directional measurement and control network intended for investigating horizontal displacements. For this purpose it uses the notion of entropy as a logarithmical measure of probability of the state of a particular observation system. An optimum number of observations results from the difference of the entropy of the vector of parameters ΔHX̂ (x)corresponding to one extra observation. An increment of entropy interpreted as an increment of the amount of information about the state of the system determines the adoption or rejection of another extra observation to be carried out.

Green peach aphid and potato leafroll virus: transmission and control

2020 ◽  
Author(s):  
R.A. Bagrov ◽  
◽  
V.I. Leunov
Keyword(s):  
Myzus Persicae ◽  
Green Peach Aphid ◽  
Virus Transmission ◽  
Potato Leafroll Virus ◽  
Factors Affecting ◽  
Potato Viruses ◽  
Tuber Necrosis ◽  
Aphid Vectors ◽  
Leafroll Virus ◽  
And Control

The mechanisms of transmission of potato viruses from plants to aphid vectors and from aphids to uninfected plants are described, including the example of the green peach aphid (Myzus persicae, GPA). Factors affecting the spreading of tuber necrosis and its manifestation on plants infected with potato leafroll virus (PLRV) are discussed. Recommendations for PLRV and GPA control in the field are given.

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