Records Added in September 2020
Records added in September 2020
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Showing records 51 to 59 of 59. [First] Page: 1 2 3 Last
Adaptive Control Strategy of Energy Storage System Participating in Primary Frequency Regulation
Chaoxiong Fang, Yuchen Tang, Rong Ye, Zhangsui Lin, Zhenshan Zhu, Buying Wen, Chengtao Ye
September 15, 2020 (v1)
Keywords: drop control, Energy Storage, primary frequency regulation, virtual inertial control
In order to solve the capacity shortage problem in power system frequency regulation caused by large-scale integration of renewable energy, the battery energy storage-assisted frequency regulation is introduced. In this paper, an adaptive control strategy for primary frequency regulation of the energy storage system (ESS) was proposed. The control strategy combined virtual droop control, virtual inertial control, and virtual negative inertial control. The virtual inertial control was used to reduce the frequency change rate, and the virtual droop control was used to reduce the steady-state frequency deviation. The virtual droop control and the virtual inertia control were adopted in the frequency deterioration stage to slow down the frequency drop. While in the frequency recovery stage, the virtual negative inertia control worked together with the virtual droop control to accelerate the frequency recovery. Besides, the coefficients of the control methods were related to the state of ch... [more]
Air-Forced Flow in Proton Exchange Membrane Fuel Cells: Calculation of Fan-Induced Friction in Open-Cathode Conduits with Virtual Roughness
Dejan Brkić, Pavel Praks
September 15, 2020 (v1)
Keywords: Colebrook equation, flow friction factor, Fuel Cells, numerically stabile solution, open-cathode, pressure drop, roughness, symbolic regression
Measurements of pressure drop during experiments with fan-induced air flow in the open-cathode proton exchange membrane fuel cells (PEMFCs) show that flow friction in its open-cathode side follows logarithmic law similar to Colebrook’s model for flow through pipes. The stable symbolic regression model for both laminar and turbulent flow presented in this article correlates air flow and pressure drop as a function of the variable flow friction factor which further depends on the Reynolds number and the virtual roughness. To follow the measured data, virtual inner roughness related to the mesh of conduits of fuel cell used in the mentioned experiment is 0.03086, whereas for pipes, real physical roughness of their inner pipe surface goes practically from 0 to 0.05. Numerical experiments indicate that the novel approximation of the Wright-ω function reduced the computational time from half of a minute to fragments of a second. The relative error of the estimated friction flow factor is les... [more]
Investigating Vapour Cloud Explosion Dynamic Fatality Risk on Offshore Platforms by Using a Grid-Based Framework
Usama Muhammad Niazi, Mohammad Shakir Nasif, Masdi Muhammad, Faisal Khan
September 15, 2020 (v1)
Keywords: Bayesian inference, CFD modelling, grid-based approach, human fatality dynamic risk, vapour cloud explosions
The reliability of petroleum offshore platform systems affects human safety and well-being; hence, it should be considered in plant design and operation in order to determine its effect on human fatality risk. Methane Vapour Cloud Explosions (VCE) in offshore platforms are known to be one of the fatal potential accidents that can be attributed to failure in plant safety systems. Traditional Quantitative Risk Analysis (QRA) lacks in providing microlevel risk assessment studies and are unable to update risk with the passage of time. This study proposes a grid-based dynamic risk analysis framework for analysing the effect of VCEs on the risk of human fatality in an offshore platform. Flame Acceleration Simulator (FLACS), which is a Computational Fluid Dynamics (CFD) software, is used to model VCEs, taking into account different wind and leakage conditions. To estimate the dynamic risk, Bayesian Inference (BI) is utilised using Accident Sequence Precursor (ASP) data. The proposed framework... [more]
Characteristics of Gliding Arc Plasma and Its Application in Swirl Flame Static Instability Control
Weiqi Chen, Di Jin, Wei Cui, Shengfang Huang
September 15, 2020 (v1)
Subject: Other
Keywords: discharge characteristics, gliding arc plasma, static instability control, swirl flame
Based on an experimental system involving a pulsating airflow burner and gliding arc generator, the characteristics of gliding arc plasma at different flow rates and its control effect on the static instability of the swirl flame have been studied. The current, voltage, and power wave forms, as well as the simultaneous evolution of plasma topology, were measured to reveal the discharge characteristics of the gliding arc. A bandpass filter was used to capture the chemiluminescence of CH in the flame, and pressure at the burner outlet was acquired to investigate the static instability. Experimental results showed that there were two different discharge types in gliding arc plasma. With the low flow rate, the glow type discharge was sustained and the current was nearly a sine wave with hundreds of milliamperes of amplitude. With the high flow rate, the spark type discharge appeared and spikes which approached almost 1 ampere in 1 μs were found in the current waveform. The lean blowout lim... [more]
Understanding the Effect of Granulation and Milling Process Parameters on the Quality Attributes of Milled Granules
Lalith Kotamarthy, Nirupaplava Metta, Rohit Ramachandran
September 15, 2020 (v1)
Subject: Biosystems
Keywords: batch loading, granule critical quality attributes, mill critical process parameters, milling, milling regimes, wet granulation
Milling is an essential unit operation used for particle size reduction in solid oral dosage manufacturing. The breakage of particles in a comil is due to the intense shear applied on the particles between impeller and the screen. Breakage also occurs due to the impact from a rotating impeller. Particles exit the mill based on their size relative to the aperture size of the screen bores. This study was set up to understand the working of the comil better. A new CPP (Critical Process Parameter), in the form of batch loading was identified. It was found that there are two different regimes (quasi static regime and impact regime) in which a comil generally operates, and the effect of the CPP’s (batch loading and impeller speed) on these regimes was studied. Knowledge of the effect of upstream operations on a particular unit operation is of significant importance, especially for pharmaceutical industry. For this reason, the effect of granulation variables such as liquid-to-solid ratio, gra... [more]
Generalization of the FOPDT Model for Identification and Control Purposes
Cristina I. Muresan, Clara M. Ionescu
September 15, 2020 (v1)
Keywords: first order plus dead time model, fractional order control, fractional order delay, fractional order system, frequency response, gain margin, phase margin, stability
This paper proposes a theoretical framework for generalization of the well established first order plus dead time (FOPDT) model for linear systems. The FOPDT model has been broadly used in practice to capture essential dynamic response of real life processes for the purpose of control design systems. Recently, the model has been revisited towards a generalization of its orders, i.e., non-integer Laplace order and fractional order delay. This paper investigates the stability margins as they vary with each generalization step. The relevance of this generalization has great implications in both the identification of dynamic processes as well as in the controller parameter design of dynamic feedback closed loops. The discussion section addresses in detail each of this aspect and points the reader towards the potential unlocked by this contribution.
Monitoring of Biochemical Parameters and GHG Emissions in Bioaugmented Manure Composting
Cevat Yaman
September 15, 2020 (v1)
Keywords: bioaugmentation, C:N ratio, greenhouse gas (GHG), agronomic testing, manure, windrow composting
Composting is a sustainable alternative for the management of manure. In this study, the effects of bioaugmentation on cattle manure composting was investigated. In this study, two windrow piles were placed at 1.7 m in height, 2.1 m in bottom width, 0.6 m in top width, and 54 m in length. Microbial inoculum was added to pile 1, whereas the second pile was used as the control. After 17 days, the C:N ratio was reduced from 25.6 to 13.6 and the total nitrogen was increased from 1.89% to 3.36% in pile 1. The dominant bacteria identified in the compost samples belonged to the genera Clostridium, Bacillus, and Flavobacterium. Quantitative polymerase chain reaction indicated that the most commonly known pathogenic bacteria, Escherichia coli, Shigella, and Salmonella, were not detected in the finished material, indicating that the pathogenic microorganisms were inactivated by the composting process. Agronomic testing for cured compost indicated a C:N ratio of less than 15 and NH+4-N:NO3−-N rat... [more]
Effect of Oxaliplatin on Voltage-Gated Sodium Channels in Peripheral Neuropathic Pain
Woojin Kim
September 15, 2020 (v1)
Subject: Biosystems
Keywords: allodynia, oxaliplatin, peripheral neuropathic pain, voltage-gated sodium channel
Oxaliplatin is a chemotherapeutic drug widely used to treat various types of tumors. However, it can induce a serious peripheral neuropathy characterized by cold and mechanical allodynia that can even disrupt the treatment schedule. Since the approval of the agent, many laboratories, including ours, have focused their research on finding a drug or method to decrease this side effect. However, to date no drug that can effectively reduce the pain without causing any adverse events has been developed, and the mechanism of the action of oxaliplatin is not clearly understood. On the dorsal root ganglia (DRG) sensory neurons, oxaliplatin is reported to modify their functions, such as the propagation of the action potential and induction of neuropathic pain. Voltage-gated sodium channels in the DRG neurons are important, as they play a major role in the excitability of the cell by initiating the action potential. Thus, in this small review, eight studies that investigated the effect of oxalip... [more]
Control of Specific Growth Rate in Fed-Batch Bioprocesses: Novel Controller Design for Improved Noise Management
Yann Brignoli, Brian Freeland, David Cunningham, Michal Dabros
September 15, 2020 (v1)
Keywords: bioprocess monitoring and control, dielectric spectroscopy, microbial bioprocessing, PAT, signal noise management, specific growth rate control
Accurate control of the specific growth rate (µ) of microorganisms is dependent on the ability to quantify the evolution of biomass reliably in real time. Biomass concentration can be monitored online using various tools and methods, but the obtained signal is often very noisy and unstable, leading to inaccuracies in the estimation of μ. Furthermore, controlling the growth rate is challenging as the process evolves nonlinearly and is subject to unpredictable disturbances originating from the culture’s metabolism. In this work, a novel feedforward-feedback controller logic is presented to counter the problem of noise and oscillations in the control variable and to address the exponential growth dynamics more effectively. The controller was tested on fed-batch cultures of Kluyveromyces marxianus, during which μ was estimated in real time from online biomass concentration measurements obtained with dielectric spectroscopy. It is shown that the specific growth rate can be maintained at dif... [more]
Showing records 51 to 59 of 59. [First] Page: 1 2 3 Last
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