scholarly journals Assessment of energy efficiency and performance in a two-phase anaerobic process for organic matter removal

2021 ◽  
Author(s):  
Andrea D. P. Hurtado ◽  
Diana M. Hernández ◽  
Karol L. Fuentes ◽  
Tatiana R. Chaparro
Keyword(s):  
Energy Efficiency ◽  
Synthetic Wastewater ◽  
Two Phase ◽  
Heating Value ◽  
The Real ◽  
Practical Applications ◽  
And Performance ◽  
The Stability ◽  
Lower Heating ◽  
The Ideal

Abstract The energy efficiency (EE) depends mainly on the lower heating values (LHVs) of hydrogen and methane selected from the thermodynamics tables at ideal conditions. However, for practical applications, the heating value should be calculated by considering some environmental factors under real conditions. Accordingly, this study compares the EE using the ideal LHV with the EE using the real LHV in a two-phase AD reactor treating synthetic wastewater. Additionally, the process performance and the stability were studied. The results show that the EE value calculated using LHVideal was, on average, 35% higher than that evaluated using LHVreal; these differences are relevant to the estimation of the real energy and also for the practical applications. At the same time, the index buffer IA/PA (intermediate alkalinity/partial alkalinity) showed to be more accurate than the value of the pH to analyze the stability of the process. With regard to COD, the removal efficiency in the methanogenic phase decreases drastically by utilizing 100% of the acidogenic phase. Future considerations in the optimization of each phase are highlighted.

scholarly journals Evaluation of a Mesoscale Thermal Actuator in Open and Closed Operating Cycles

2019 ◽  
Author(s):  
Sindhu Preetham Burugupally
Keyword(s):  
Heat Input ◽  
Scaling Laws ◽  
Lumped Parameter Model ◽  
Thermal Actuator ◽  
Closed Cycle ◽  
Two Phase ◽  
Practical Applications ◽  
Thermal Actuators ◽  
Large Force ◽  
And Performance

Thermal-based actuators are known for generating large force and displacement strokes at mesoscale (millimeter) regime. In particular, two-phase thermal actuators are found to benefit from the scaling laws of physics at mesoscale to offer large force and displacement strokes; but they have low thermal efficiencies. As an alternative, a combustion-based thermal actuator is proposed and its performance is studied in both open and closed cycle operations. Through a physics-based lumped-parameter model, we investigate the behavior and performance of the actuator using a spring-mass-damper analogy and taking an air standard cycle approach. Three observations are reported: (1) the mesoscale actuator can generate peak forces of up to 400 N and displacement strokes of about 16 cm suitable for practical applications; (2) an increase in heat input to the actuator results in increasing the thermal efficiency of the actuator for both open and closed cycles; and (3) for a specific heat input, both the open and closed cycle operations respond differently \textemdash different stroke lengths, peak pressures, and thermal efficiencies.

scholarly journals Comparison of Fuel Yield of Biomaterials Between Fast Pyrolysis and Gasification

2017 ◽  
Vol 4 ◽  
pp. 2-16
Author(s):  
Matthew Charles Stokes Hughes ◽  
Lachlan Mcfall ◽  
Matthew Christiansen ◽  
Nicholas Zepernick
Keyword(s):  
Fast Pyrolysis ◽  
High Carbon ◽  
Primary Methods ◽  
Heating Value ◽  
Cotton Stalks ◽  
Lower Heating Value ◽  
Bio Oil ◽  
Viable Method ◽  
Lower Heating ◽  
The Ideal

Pyrolysis is a viable method of extracting combustible fuels as gases or liquids from various, high carbon and hydrogen containing biomaterials. This Meta-study attempts to find the ideal combinations of processes for maximising biofuel output by comparing a range of biomaterials (cotton stalks, algae and peach scraps), put through the two primary methods of pyrolysis, through analysis of reactor type, Temperature, particle size and lower heating value achieved from biofuel output. It is proposed that the fast pyrolysis of Algae in a Fluidized bed reactor at a temperature of 550°C is the optimum combination of parameters for maximising biofuel output in terms of bio-oil yield and lower heating value (LHV) in kJ/kg.

scholarly journals Multiphase Trajectory Generation for Planar Biped Robot Using Direct Collocation Method

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yubin Liu ◽  
Shuai Heng ◽  
Xizhe Zang ◽  
Zhenkun Lin ◽  
Jie Zhao
Keyword(s):  
Energy Efficiency ◽  
Collocation Method ◽  
Biped Robot ◽  
Contact Forces ◽  
Two Phase ◽  
Double Support ◽  
Direct Collocation ◽  
Direct Collocation Method ◽  
The Stability ◽  
Support Phase

Stability and energy efficiency are the main focuses in the bipedal robot field. In this paper, we apply a multiphase gait, which is different from the widely used two-phase gait, to improve the stability at the moment, when a biped robot transfers from the double support phase to the single support phase. Then, we create dynamic equations with contact forces in each phase using Lagrangian formulation. Furthermore, the direct collocation method is utilized to generate the optimal trajectory toward both stability and energy efficiency. Finally, the comparison between multiphase gait and two-phase gait is performed with numerical simulations. The results prove that multiphase gait increases the stability margin in the cost of slightly decreasing energy efficiency. Besides, both gaits show a similar human-like characteristic in hip height variation during walking.

The influence of the Stokes and Archimedes forces on the stability of a two-phase flow

2003 ◽  
Vol 3 ◽  
pp. 266-270
Author(s):  
B.H. Khudjuyerov ◽  
I.A. Chuliev
Keyword(s):  
Spectral Method ◽  
Stability Region ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Solid Phase ◽  
Stability Characteristic ◽  
Phase Flow ◽  
Two Phase ◽  
The Stability

The problem of the stability of a two-phase flow is considered. The solution of the stability equations is performed by the spectral method using polynomials of Chebyshev. A decrease in the stability region gas flow with the addition of particles of the solid phase. The analysis influence on the stability characteristic of Stokes and Archimedes forces.

scholarly journals Medical identity; perspectives of students from two countries

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Conor Gilligan ◽  
Teresa Loda ◽  
Florian Junne ◽  
Stephan Zipfel ◽  
Brian Kelly ◽  
...  
Keyword(s):  
Medical Education ◽  
Professional Identity ◽  
Cultural Differences ◽  
Mental Image ◽  
Educational Interventions ◽  
The Real ◽  
Self Image ◽  
Medical Program ◽  
Polarity Profile ◽  
The Ideal

Abstract Background The development of professional identity is a fundamental element of medical education. There is evidence that in Germany, students’ perceptions of the ideal and real doctor differ, and that of themselves as physicians falls between these constructs. We sought to compare students’ perceptions of themselves, the ideal doctor, and the ‘real’ doctor and investigate differences from first to final year in the relationships between these constructs, as well as differences between Australian and German cohorts. Method Students in the first and final years of their medical program at one Australian and one German university were invited to complete the Osgood and Hofstatter polarity profile, involving the description of their mental image of the ideal and real doctor, and the doctor they hope to become, with adjectives provided. Results One hundred sixty-seven students completed the survey in Australia (121 year 1, 46 year 5) and 188 in Germany (164 year 1, 24 year 6). The perception of the ideal doctor was consistent across all respondents, but that of the real doctor and self-image differed between country and year. Differences existed between country cohorts in perceptions of ‘confidence’, ‘strength’, ‘capability’ and ‘security’. Conclusions The pattern previously reported among German students was maintained, but a different pattern emerged among Australian students. Differences between countries could reflect cultural differences or variations in the overt and hidden curricula of medical schools. Some of the constructs within the profiles are amenable to educational interventions to improve students’ confidence and sense of capability.

scholarly journals Power and Performance Evaluation of Memory-Intensive Applications

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4089
Author(s):  
Kaiqiang Zhang ◽  
Dongyang Ou ◽  
Congfeng Jiang ◽  
Yeliang Qiu ◽  
Longchuan Yan
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Power Consumption ◽  
Job Scheduling ◽  
Memory System ◽  
Processor Core ◽  
Memory Efficiency ◽  
And Performance ◽  
Reasonable Use ◽  
Server System

In terms of power and energy consumption, DRAMs play a key role in a modern server system as well as processors. Although power-aware scheduling is based on the proportion of energy between DRAM and other components, when running memory-intensive applications, the energy consumption of the whole server system will be significantly affected by the non-energy proportion of DRAM. Furthermore, modern servers usually use NUMA architecture to replace the original SMP architecture to increase its memory bandwidth. It is of great significance to study the energy efficiency of these two different memory architectures. Therefore, in order to explore the power consumption characteristics of servers under memory-intensive workload, this paper evaluates the power consumption and performance of memory-intensive applications in different generations of real rack servers. Through analysis, we find that: (1) Workload intensity and concurrent execution threads affects server power consumption, but a fully utilized memory system may not necessarily bring good energy efficiency indicators. (2) Even if the memory system is not fully utilized, the memory capacity of each processor core has a significant impact on application performance and server power consumption. (3) When running memory-intensive applications, memory utilization is not always a good indicator of server power consumption. (4) The reasonable use of the NUMA architecture will improve the memory energy efficiency significantly. The experimental results show that reasonable use of NUMA architecture can improve memory efficiency by 16% compared with SMP architecture, while unreasonable use of NUMA architecture reduces memory efficiency by 13%. The findings we present in this paper provide useful insights and guidance for system designers and data center operators to help them in energy-efficiency-aware job scheduling and energy conservation.

scholarly journals Refrigeration of COVID-19 Vaccines: Ideal Storage Characteristics, Energy Efficiency and Environmental Impacts of Various Vaccine Options

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1849
Author(s):  
Alexandre F. Santos ◽  
Pedro D. Gaspar ◽  
Heraldo J. L. de Souza
Keyword(s):  
Energy Efficiency ◽  
Environmental Impacts ◽  
Thermal Load ◽  
Storage Condition ◽  
Storage Conditions ◽  
Energy Simulation ◽  
Energy Usage ◽  
Impact Simulation ◽  
Storage Characteristics ◽  
The Ideal

This article considers the ideal storage conditions for multiple vaccine brands, such as Pfizer, Moderna, CoronaVac, Oxford–AstraZeneca, Janssen COVID-19 and Sputnik V. Refrigerant fluid options for each storage condition, thermal load to cool each type of vaccine and environmental impacts of refrigerants are compared. An energy simulation using the EUED (energy usage effectiveness design) index was developed. The Oxford–AstraZeneca, Janssen COVID-19 and CoronaVac vaccines show 9.34-times higher energy efficiency than Pfizer. In addition, a TEWI (total equivalent warming impact) simulation was developed that prioritizes direct environmental impacts and indirect in refrigeration. From this analysis, it is concluded that the cold storage of Oxford–AstraZeneca, Janssen COVID-19 and CoronaVac vaccines in Brazil generates 35-times less environmental impact than the Pfizer vaccine.

scholarly journals Performance Evaluation of Heading-and-Winning Machines in the Conditions of Potash Mines

2021 ◽  
Vol 11 (8) ◽  
pp. 3444
Author(s):  
Sergey A. Lavrenko ◽  
Dmitriy I. Shishlyannikov
Keyword(s):  
Energy Efficiency ◽  
Experimental Studies ◽  
Efficiency Coefficient ◽  
Mechanized Method ◽  
Methodological Approaches ◽  
The Stability ◽  
Technical Solutions ◽  
Potash Mine ◽  
Complex Indicators ◽  
Potassium Magnesium

The authors focus on the process of potash ore production by a mechanized method. They show that currently there are no approved procedures for assessing the performance of heading-and-winning machines operating in the conditions of potash mines. This causes difficulties in determining the field of application of heading-and-winning machines, complicates the search for implicit technical solutions for the modernisation of existing models of mining units, prohibits real-time monitoring of the stability of stope-based technological processes and makes it difficult to assess the performance of the services concerning mining enterprises. The work represents an aggregate assessment of the performance of heading-and-winning machines for potash mines by determining complex indicators describing the technological and technical levels of organising the work in stopes. Such indicators are the coefficients of productivity and energy efficiency, respectively. Experimental studies have been carried out in the conditions of the potash mine of the Verkhnekamskoye potassium-magnesium salt deposit to assess the performance of the latest and most productive Ural-20R heading-and-winning machines manufactured in Russia. Using the above methodological approaches, this paper shows that the unsatisfactory technological performance of the studied machine is due to the low productivity of the mine district transport. The average productivity coefficient was 0.29. At the same time, high values of the energy efficiency coefficient show that the productivity of the machine is on par with design conditions.

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