Inertia tensor estimation for a rigid nadir pointing satellite based on star tracker

Cheriet, Mohammed E.A.,Bellar, Abdellatif,Ghaffour, Mohammed Y.,Adnane, Akram,Mohammed, Mohammed A. SI Techno-Press 2021 Advances in aircraft and spacecraft science Vol.8 No.2

Accurate inertia properties information is important to reach an optimized estimation of attitude and precise control of a rigid spacecraft. Unfortunately, the satellite is succumbing several influences that can affect the inertia properties, such as fuel consumption and sloshing. Thus, this work inspects the use of star tracker to estimate the attitude, angular velocity and moment of inertia for a rigid nadir pointing satellite by employing extended Kalman filter, without any prior information about the nominal inertia matrix. The proposed estimator is applied in nadir pointing mode and without any constant control torque to avoid the attitude tumbling during the estimation phase, which in turn leads to a catastrophic failure of the satellite mission. The simulation results are compared to three other approaches and validated by Monte Carlo method that elucidates the good performance of the suggested approach and demonstrates its efficiency in satellite inertia tensor and attitude estimation even in worst situations.

A closed-loop forward osmosis-nanofiltration hybrid system: Understanding process implications through full-scale simulation

Phuntsho, Sherub,Kim, Jung Eun,Hong, Seungkwan,Ghaffour, Noreddine,Leiknes, TorOve,Choi, Joon Yong,Shon, Ho Kyong Elsevier Scientific Pub. Co 2017 Desalination Vol. No.

<P><B>Abstract</B></P> <P>This study presents simulation of a closed-loop forward osmosis (FO)-nanofiltration (NF) hybrid system using fertiliser draw solution (DS) based on thermodynamic mass balance in a full-scale system neglecting the non-idealities such as finite membrane area that may exist in a real process. The simulation shows that the DS input parameters such as initial concentrations and its flow rates cannot be arbitrarily selected for a plant with defined volume output. For a fixed FO-NF plant capacity and feed concentration, the required initial DS flow rate varies inversely with the initial DS concentration or vice-versa. The net DS mass flow rate, a parameter constant for a fixed plant capacity but that increases linearly with the plant capacity and feed concentration, is the most important operational parameter of a closed-loop system. Increasing either of them or both increases the mass flow rate to the system directly affecting the final concentration of the diluted DS with direct energy implications to the NF process. Besides, the initial DS concentration and flow rates are also limited by the optimum recovery rates at which NF process can be operated which otherwise also have direct implications to the NF energy. This simulation also presents quantitative analysis of the reverse diffusion of fertiliser nutrients towards feed brine and the gradual accumulation of feed solutes within the closed system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Initial DS flow rate and concentration cannot be set at any arbitrary values. </LI> <LI> Initial DS flow rate and concentration vary inversely for a fixed plant capacity. </LI> <LI> Net DS mass flow rate <I>m</I> <SUB>D</SUB> is the most important parameter for a closed system. </LI> <LI> <I>m</I> <SUB>D</SUB> is constant for a fixed plant capacity but increases with capacity and feed TDS. </LI> <LI> FO and NF rejection rates influence feed solute accumulation in the closed system. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Inertia tensor estimation for a rigid nadir pointing satellite based on star tracker

Cheriet, Mohammed E.A.,Bellar, Abdellatif,Ghaffour, Mohammed Y.,Adnane, Akram,Mohammed, Mohammed A. SI Techno-Press 2021 Advances in aircraft and spacecraft science Vol.8 No.2

Accurate inertia properties information is important to reach an optimized estimation of attitude and precise control of a rigid spacecraft. Unfortunately, the satellite is succumbing several influences that can affect the inertia properties, such as fuel consumption and sloshing. Thus, this work inspects the use of star tracker to estimate the attitude, angular velocity and moment of inertia for a rigid nadir pointing satellite by employing extended Kalman filter, without any prior information about the nominal inertia matrix. The proposed estimator is applied in nadir pointing mode and without any constant control torque to avoid the attitude tumbling during the estimation phase, which in turn leads to a catastrophic failure of the satellite mission. The simulation results are compared to three other approaches and validated by Monte Carlo method that elucidates the good performance of the suggested approach and demonstrates its efficiency in satellite inertia tensor and attitude estimation even in worst situations.

Evaluation of Biofouling in a Forward Osmosis - Reverse Osmosis Integrated Seawater Desalination System

Youngjin Kim,Lanhee Kim,Noreddine Ghaffour 한국막학회 2020 한국막학회 총회 및 학술발표회 Vol.2020 No.11

Assessing the removal of organic micropollutants by a novel baffled osmotic membrane bioreactor-microfiltration hybrid system

Pathak, Nirenkumar,Li, Sheng,Kim, Youngjin,Chekli, Laura,Phuntsho, Sherub,Jang, Am,Ghaffour, Noreddine,Leiknes, TorOve,Shon, Ho Kyong Elsevier 2018 Bioresource technology Vol.262 No.-

<P><B>Abstract</B></P> <P>A novel approach was employed to study removal of organic micropollutants (OMPs) in a baffled osmotic membrane bioreactor-microfiltration (OMBR-MF) hybrid system under oxicanoxic conditions. The performance of OMBR-MF system was examined employing three different draw solutes (DS), and three model OMPs. The highest forward osmosis (FO) membrane rejection was attained with atenolol (100%) due to its higher molar mass and positive charge. With inorganic DS caffeine (94–100%) revealed highest removal followed by atenolol (89–96%) and atrazine (16–40%) respectively. All three OMPs exhibited higher removal with organic DS as compared to inorganic DS. Significant anoxic removal was observed for atrazine under very different redox conditions with extended anoxic cycle time. This can be linked with possible development of different microbial consortia responsible for diverse enzymes secretion. Overall, the OMBR-MF process showed effective removal of total organic carbon (98%) and nutrients (phosphate 97% and total nitrogen 85%), respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hybrid OMBR-MF examined for OMPs and nutrient removal from simulated sewage. </LI> <LI> Performance of inorganic and organic draw solutes in OMBR-MF system assessed. </LI> <LI> Baffled OMBR-MF achieved high removal for nutrient and OMPs. </LI> <LI> Persistent OMP like atrazine exhibited high anoxic removal compared to oxic. </LI> <LI> Atenolol showed highest forward osmosis rejection due to high molar mass. </LI> <LI> Large microbial flocs contributed to lower membrane fouling propensity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of seawater-coolant feed arrangement in a waste heat driven multi-stage vacuum membrane distillation system

Lee, Jung-Gil,Bak, Chul-u,Thu, Kyaw,Ghaffour, Noreddine,Kim, Young-Deuk Elsevier 2019 Separation and purification technology Vol.212 No.-

<P><B>Abstract</B></P> <P>This paper proposes two types of seawater-coolant feed arrangements of a heat recovery unit (HRU) for improving the performance of a multi-stage vacuum membrane distillation (VMD) system: backward feed (BF) and parallel feed (PF). Theoretical studies were performed to assess the effect of the BF and PF feed arrangements on the system performance. In addition, to comprehensively understand the thermochemical phenomena in both the BF and PF arrangements, spatial variations in the temperature, permeate pressure, permeate flux, and salinity were investigated using a rigorous simulation model that considered the heat and mass transfer across the hollow fibers coupled with the transport behavior on the feed side. To determine the superior HRU configuration between BF and PF, the water production, recovery ratio, and specific energy consumption of the multi-stage VMD system were investigated. It was found that the total water production in the PF arrangement was approximately 2.94 m<SUP>3</SUP>/d, which was approximately 6% higher than in the BF arrangement; however, the BF arrangement was more efficient for the production of freshwater than the PF arrangement when a smaller number of module stages was employed. Furthermore, the optimum number of HRUs in the BF arrangement was determined based on this theoretical study.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effect of BF and PF arrangements on MVMD system performance was theoretically evaluated. </LI> <LI> BF arrangement with a smaller number of module stages was more efficient for water production. </LI> <LI> Inappropriate number of module stages had a negative effect on MVMD system performance. </LI> <LI> Four HRU stages with BF arrangement showed an improved efficiency of the MVMD system. </LI> </UL> </P>

Human urine as a forward osmosis draw solution for the application of microalgae dewatering

Volpin, Federico,Yu, Hyeonjung,Cho, Jaeweon,Lee, Changsoo,Phuntsho, Sherub,Ghaffour, Noreddine,Vrouwenvelder, Johannes S.,Shon, Ho Kyong Elsevier 2019 Journal of hazardous materials Vol.378 No.-

<P><B>Abstract</B></P> <P>Human urine is a unique solution that has the right composition to constitute both a severe environmental threat and a rich source of nitrogen and phosphorous. In fact, between 4–9% of urine mass consists of ions, such as K<SUP>+</SUP>, Cl<SUP>−</SUP>, Na<SUP>+</SUP> or NH<SUB>4</SUB> <SUP>+</SUP>. Because of its high ionic strength, urine osmotic pressure can reach values of up to 2000 kPa. With this in mind, this work aimed to study the effectiveness of real urine as a novel draw solution for forward osmosis. Water flux, reverse nitrogen flux and membrane fouling were investigated using fresh or hydrolysed urine. Water flux as high as 16.7 ± 1.1 L m<SUP>−2</SUP> h<SUP>−1</SUP> was recorded using real hydrolysed urine.</P> <P>Additionally, no support layer membrane fouling was noticed in over 20 h of experimentation. Urine was also employed to dewater a <I>Chlorella vulgaris</I> culture. A fourfold increase in algal concentration was achieved while having an average flux of 14.1 L m<SUP>−2</SUP> h<SUP>−1</SUP>. During the algae dewatering, a flux decrease of about 19% was noticed; this was mainly due to a thin layer of algal deposition on the active side of the membrane. Overall, human urine was found to be an effective draw solution for forward osmosis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrolysed urine can reach more than 2000 kPa in osmotic pressure. </LI> <LI> Real urine exhibited flux up to 16.7 ± 1.1 L m<SUP>−2</SUP> h<SUP>−1</SUP>. </LI> <LI> Support layer fouling caused by unfiltered urine was found negligible. </LI> <LI> Four times algal concentration was achieved using real urine as draw solution. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A novel integrated thermal-/membrane-based solar energy-driven hybrid desalination system: Concept description and simulation results

Kim, Y.D.,Thu, K.,Ng, K.C.,Amy, G.L.,Ghaffour, N. Pergamon Press 2016 Water research Vol.100 No.-

In this paper, a hybrid desalination system consisting of vacuum membrane distillation (VMD) and adsorption desalination (AD) units, designated as VMD-AD cycle, is proposed. The synergetic integration of the VMD and AD is demonstrated where a useful effect of the AD cycle is channelled to boost the operation of the VMD process, namely the low vacuum environment to maintain the high pressure gradient across the microporous hydrophobic membrane. A solar-assisted multi-stage VMD-AD hybrid desalination system with temperature modulating unit is first designed, and its performance is then examined with a mathematical model of each component in the system and compared with the VMD-only system with temperature modulating and heat recovery units. The total water production and water recovery ratio of a solar-assisted 24-stage VMD-AD hybrid system are found to be about 21% and 23% higher, respectively, as compared to the VMD-only system. For the solar-assisted 24-stage VMD-AD desalination system having 150 m<SUP>2</SUP> of evacuated-tube collectors and 10 m<SUP>3</SUP> seawater storage tanks, both annual collector efficiency and solar fraction are close to 60%.

A novel multi-stage direct contact membrane distillation module: Design, experimental and theoretical approaches

Lee, Jung-Gil,Kim, Woo-Seung,Choi, June-Seok,Ghaffour, Noreddine,Kim, Young-Deuk Elsevier 2016 Water research Vol.107 No.-

<P><B>Abstract</B></P> <P>An economic desalination system with a small scale and footprint for remote areas, which have a limited and inadequate water supply, insufficient water treatment and low infrastructure, is strongly demanded in the desalination markets. Here, a direct contact membrane distillation (DCMD) process has the simplest configuration and potentially the highest permeate flux among all of the possible MD processes. This process can also be easily instituted in a multi-stage manner for enhanced compactness, productivity, versatility and cost-effectiveness. In this study, an innovative, multi-stage, DCMD module under countercurrent-flow configuration is first designed and then investigate both theoretically and experimentally to identify its feasibility and operability for desalination application. Model predictions and measured data for mean permeate flux are compared and shown to be in good agreement. The effect of the number of module stages on the mean permeate flux, performance ratio and daily water production of the MDCMD system has been theoretically identified at inlet feed and permeate flow rates of 1.5 l/min and inlet feed and permeate temperatures of 70 °C and 25 °C, respectively. The daily water production of a three-stage DCMD module with a membrane area of 0.01 m<SUP>2</SUP> at each stage is found to be 21.5 kg.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An innovative MDCMD module with a countercurrent-flow configuration is proposed. </LI> <LI> Feasibility and operability of module design are demonstrated experimentally and theoretically. </LI> <LI> Model predictions and measured data for mean permeate flux are shown to be in good agreement. </LI> <LI> Effect of the number of module stages on the performance of the MDCMD system is identified. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Environmental and economic impacts of fertilizer drawn forward osmosis and nanofiltration hybrid system

Kim, Jung Eun,Phuntsho, Sherub,Chekli, Laura,Hong, Seungkwan,Ghaffour, Noreddine,Leiknes, TorOve,Choi, Joon Yong,Shon, Ho Kyong Elsevier 2017 Desalination Vol.416 No.-

<P><B>Abstract</B></P> <P>Environmental and economic impacts of the fertilizer drawn forward osmosis (FDFO) and nanofiltration (NF) hybrid system were conducted and compared with conventional reverse osmosis (RO) hybrid scenarios using microfiltration (MF) or ultrafiltration (UF) as a pre-treatment process. The results showed that the FDFO-NF hybrid system using thin film composite forward osmosis (TFC) FO membrane has less environmental impact than conventional RO hybrid systems due to lower consumption of energy and cleaning chemicals. The energy requirement for the treatment of mine impaired water by the FDFO-NF hybrid system was 1.08kWh/m<SUP>3</SUP>, which is 13.6% less energy than an MF-RO and 21% less than UF-RO under similar initial feed solution. In a closed-loop system, the FDFO-NF hybrid system using a TFC FO membrane with an optimum NF recovery rate of 84% had the lowest unit operating expenditure of AUD $0.41/m<SUP>3</SUP>. Besides, given the current relatively high price and low flux performance of the cellulose triacetate and TFC FO membranes, the FDFO-NF hybrid system still holds opportunities to reduce operating expenditure further. Optimizing NF recovery rates and improving the water flux of the membrane would decrease the unit OPEX costs, although the TFC FO membrane would be less sensitive to this effect.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Environmental impacts of the FDFO-NF(TFC) hybrid system can be lower than RO hybrid systems. </LI> <LI> The FDFO-NF hybrid system consumes 21% less energy than the UF-RO hybrid system. </LI> <LI> The unit OPEX cost of FDFO-NF (TFC) system is 14% lower than UF-RO hybrid system. </LI> <LI> Improving flux and lowering the cost of the CTA FO membrane can make the FDFO-NF cost effective. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>