scholarly journals Study on Sludge and Dissolved Oxygen Distribution in a Full-Scale A2/O Oxidation Ditch

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2776
Author(s):  
Chengyi Li ◽  
Zhao Han ◽  
Yuquan Zhang ◽  
Yuan Zheng ◽  
Hepeng Zhang ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Flow Model ◽  
Rotation Speed ◽  
Full Scale ◽  
Oxidation Ditch ◽  
Bed Height ◽  
Consumption Rates ◽  
The Relationship ◽  
Oxygenation Rate ◽  
Biological Selection

The distribution of velocity, sludge, and dissolved oxygen in a full-scale anaerobic-anoxic-oxic (A2/O) oxidation ditch was numerically simulated under three rotation speed scenarios. The viscosity and settling rate of activated sludge were defined through a user-defined function (UDF), and the sludge phase was calculated using the mixture multiphase flow model. Dissolved oxygen (DO) was set as a user-defined source (UDS) and its generation and consumption rates were defined with UDFs. The relationship between velocity and sludge concentration was found to be contradictory, with dead zones leading to large sludge concentrations at the bottom of the oxidation ditch (OD), but not at the middle-curved wall of the anoxic pool. The flow rate of the reflux slot and aerator oxygenation rate were checked and correlated with DO concentrations in the anaerobic pool. The majority of the large sludge concentrations were concentrated in the biological selection pool and these remained constant with bed height. With reduced propeller and agitator rotation speed, the sludge concentrations reduced in the biological selection pool, but increased in the anaerobic and anoxic pools.

Pulse-Width Modulated Amplifier for DC Servo System and Its Matlab Simulation

2015 ◽  
Vol 9 (1) ◽  
pp. 625-631
Author(s):  
Ma Xiaocheng ◽  
Zhang Haotian ◽  
Cheng Yiqing ◽  
Zhu Lina ◽  
Wu Dan
Keyword(s):  
Mathematical Model ◽  
Transfer Function ◽  
Input Signal ◽  
Pulse Width ◽  
Rotation Speed ◽  
Servo Motor ◽  
Matlab Simulation ◽  
Pulse Width Modulated ◽  
Signal Changes ◽  
The Relationship

This paper introduces a mathematical model for Pulse-Width Modulated Amplifier for DC Servo Motor. The relationship between pulse-width modulated (PWM) signal and reference rotation speed is specified, and a general model of motor represented by transfer function is also put forward. When the input signal changes, the rotation speed of the servo motor will change accordingly. By changing zeros and poles, transient performance of this system is discussed in detail, and optimal ranges of the parameters is recommended at the end of discussion.

The Historiography of Environmental History

2018 ◽  
Author(s):  
J. R. McNeill
Keyword(s):  
Climate Change ◽  
Environmental History ◽  
Industrial Pollution ◽  
Full Scale ◽  
Environmental Concerns ◽  
The Us ◽  
The World ◽  
History Of ◽  
The 1960S ◽  
The Relationship

This chapter discusses the emergence of environmental history, which developed in the context of the environmental concerns that began in the 1960s with worries about local industrial pollution, but which has since evolved into a full-scale global crisis of climate change. Environmental history is ‘the history of the relationship between human societies and the rest of nature’. It includes three chief areas of inquiry: the study of material environmental history, political and policy-related environmental history, and a form of environmental history which concerns what humans have thought, believed, written, and more rarely, painted, sculpted, sung, or danced that deals with the relationship between society and nature. Since 1980, environmental history has come to flourish in many corners of the world, and scholars everywhere have found models, approaches, and perspectives rather different from those developed for the US context.

CFD Study on the Flow Characteristics in Filleted Microchannels

2011 ◽  
Vol 103 ◽  
pp. 268-273
Author(s):  
Hong Jie Yan ◽  
Ping Zhou ◽  
Ze Lin Xu ◽  
Zhuo Chen ◽  
Jing Wen Mo
Keyword(s):  
Pressure Drop ◽  
Aspect Ratio ◽  
Flow Model ◽  
Constant Width ◽  
Flow Characteristics ◽  
Flow Pressure ◽  
Cfd Method ◽  
Poiseuille Number ◽  
The Relationship ◽  
Laminar Flow Model

The flow characteristics of water in filleted microchannels were simulated based on CFD method. The flow pressure drop at different aspect ratioandRenumber were rearranged on the simulating results with laminar flow model. The results indicated that the pressure drop enlarges with the increase of in the case of the constant width of the microchannel. Within the range ofRenumber of interest, Poiseuille number of the flow is constant for differentRe, but decreases with increasing aspect ratio. An equation was fitted to describe the relationship betweenPonumber and aspect ratio, i.e. .

scholarly journals Model Shuttle Flow Dalam Pembelajaran Integratif Holistik Bahasa Indonesia Di Sekolah Dasar

2021 ◽  
Vol 5 (1) ◽  
pp. 98
Author(s):  
Sudirman Sudirman
Keyword(s):  
Elementary Schools ◽  
Primary Schools ◽  
Flow Model ◽  
Language Skills ◽  
Core Competencies ◽  
Integrative Learning ◽  
The Relationship ◽  
Self Potential ◽  
And Training ◽  
Innovative Concept

This paper is an innovative concept in the field of learning, especially Indonesian in elementary schools. The Shuttle Flow Model is an invention, the result of contemplating experiences during and after teaching, observing, and training teachers in learning practices. The existence of a ‘shuttling’ movement between values and competencies during learning and prioritizing the elements of connectedness, wholeness, and beingness are the main features of this model. The purpose of this model is to help teachers teach Indonesian in an integrative-holistic manner as well as a solution to teacher constraints in integrative learning in primary schools. This model displays the flexibility in integrating the four aspects of language skills with the core competencies in the 2013 Curriculum which flow back and forth in the direction formed by the flow of competencies. This direction shows the relationship between aspects of language skills from and to core competencies. That is why it is called the Shuttle Flow Modle or the Shuttle Flow Model. The presence of this model is so important to guide teachers in developing the self-potential of students holistically. By using this model, teachers will never run out of material in teaching, they can even find out what aspects and competencies the students are weak in. There are five strengths of this model and four weaknesses. Strengths are intensified to minimize weaknesses. It is recommended that this learning model be an innovative choice in learning in elementary schools.

scholarly journals A novel one-sided push-out test for shear connectors in composite beams

2018 ◽  
Author(s):  
Mohammed Abdulhussein Al-Shuwaili ◽  
Alessandro Palmeri ◽  
Maria Teresa Lombardo
Keyword(s):  
Shear Resistance ◽  
Composite Beams ◽  
Full Scale ◽  
Bending Tests ◽  
Shear Connectors ◽  
Shear Connections ◽  
European Standards ◽  
Headed Stud ◽  
The Relationship ◽  
Push Out

Push-out tests (POTs) have been widely exploited as an alternative to the more expensive full-scale bending tests to characterize the behaviour of shear connections in steel-concrete composite beams. In these tests, two concrete slabs are typically attached to a steel section with the connectors under investigation, which are then subjected to direct shear. The results allow quantifying the relationship between applied load and displacements at the steel-concrete interface. Since this relationship is highly influenced by the boundary conditions of POT samples, different experimental setups have been used, where the slabs are either restricted or free to slide horizontally, as researchers have tried to reduce any discrepancy between POT and full-scale composite beam testing. Based on a critical review of various POT configurations presented in the dedicated literature, this paper presents an efficient one-sided POT (OSPOT) method. While OSPOT and POT specimens are similar, in the proposed OPSPOT setup only one of the two slabs is directly loaded in each test, and the slab is free to move vertically. Thus, two results can be obtained from one specimen, i.e. one from each slab. A series of POTs and OSPOTs have been conducted to investigate the behaviour and the shear resistance of headed stud connectors through the two methods of testing. The results of this study than were compared with those of different POTs setups conducted by other researchers. The new OSPOT results show in general an excellent agreement with the analytical predictions offered by both British and European standards, as well as the estimated shear resistance proposed other researchers in the literature. These findings suggest that the proposed one-sided setup could be used as an efficient and economical option for conducting the POT, as it has the potential not only to double the number of results, but also to simplify the fabrication of the samples, which is important in any large experimental campaign, and to allow testing with limited capacity of the actuator. 

Study on the Relationship between Population Density of Noctiluca scintillans and Environmental Factors in the Coastal Waters of Qinhuangdao

2014 ◽  
Vol 1010-1012 ◽  
pp. 635-638
Author(s):  
Yan Juan Xi ◽  
Zhen Liang Zhao ◽  
Chun Long Zhao ◽  
Yan Qin Xi ◽  
Li Yan ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Population Density ◽  
Correlation Analysis ◽  
Dissolved Oxygen ◽  
Linear Correlation ◽  
Coastal Waters ◽  
Ammonia Nitrogen ◽  
Noctiluca Scintillans ◽  
Nitrite Nitrate ◽  
The Relationship

Based on the environmental survey data in off-shore of Qin Huangdao from May to June 2011,correlation analysis was made between population density of Noctiluca scintillans and environmental factors. The results indicates that population density of Noctiluca scintillans does not exist linear correlation with nitrite, nitrate, ammonia, nitrogen, phosphate,dissolved oxygen and PH ,it is positive correlation with temperature and silicate noctiluca and negatively correlation with transparency and salinity.

Quantification of energy and cost reduction from decreasing dissolved oxygen levels in full‐scale WRRFs

2021 ◽  
Author(s):  
Federico Pasini ◽  
Manel Garrido‐Baserba ◽  
Travis Sprague ◽  
Pietro Cambiaso ◽  
Diego Rosso
Keyword(s):  
Dissolved Oxygen ◽  
Cost Reduction ◽  
Full Scale ◽  
Oxygen Levels

Some Factors Affecting the Oxygen Consumption of Asellus

1960 ◽  
Vol 37 (4) ◽  
pp. 706-718
Author(s):  
R. W. EDWARDS ◽  
M. A. LEARNER
Keyword(s):  
Oxygen Consumption ◽  
Dissolved Oxygen ◽  
Constant Volume ◽  
Asellus Aquaticus ◽  
Dissolved Oxygen Concentration ◽  
Factors Affecting ◽  
Consumption Rates ◽  
Rate Of Oxygen Consumption ◽  
Wet Weight ◽  
Males And Females

1. The oxygen-consumption rates of Asellus aquaticus (males and females) have been measured at 10 and 20° C. using a constant-volume respirometer, and the effect of starvation for 24 hr. investigated. The oxygen consumption is approximately proportional to the 0.7 power of the wet weight. The rate of oxygen consumption at 20° C. is greater than at 10° C. by a factor of 1.5. 2. The oxygen-consumption rates of A. aquaticus and A. meridianus have been measured at 20° C. in a flowing-water respirometer employing a polarographic technique for the measurement of dissolved-oxygen concentrations. The oxygen consumptions of A. aquaticus and A. meridianus are similar and decrease by 15-20% when the dissolved-oxygen concentration falls from 8.3 to 1.5 p.p.m. 3. The oxygen consumption of A. aquaticus is between 35 and 75% higher in the polarographic respirometer than in the constant-volume respirometer.

scholarly journals Nonlinear Compound Control for Nonsinusoidal Vibration of the Mold Driven by Servo Motor with Variable Speed

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Qiang Li ◽  
Yi-ming Fang ◽  
Jian-xiong Li ◽  
Zhuang Ma
Keyword(s):  
Control Method ◽  
Controller Design ◽  
Rotation Speed ◽  
Pi Control ◽  
Variable Speed ◽  
Servo Motor ◽  
Motor Speed ◽  
Vector Method ◽  
Compound Control ◽  
The Relationship

In this paper, a fuzzy PI control method based on nonlinear feedforward compensation is proposed for the nonsinusoidal vibration system of mold driven by servo motor, rotated in single direction with variable speed. During controller design, there are mainly two issues to consider: (i) nonlinear relationship (approximate periodic function) between mold displacement and servo motor speed and (ii) uncertainties caused by backlash due to motor variable speed. So, firstly, the relationship between mold displacement and motor rotation speed is built directly based on the rotation vector method. Then, an observer is designed to estimate the uncertainties and feedforward compensation. Secondly, as the motor rotates in single direction with variable speed, a fuzzy control with bidirectional parameter adjustment is adopted to improve rapidity and stability based on the traditional PI method. Finally, some simulation results show the effectiveness of the proposed control method.

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