scholarly journals Eutrophication Bifurcation Analysis for Tasik Harapan Restoration

2020 ◽  
Vol 11 (8) ◽  
pp. 407-413
Author(s):  
Chai Jian Tay ◽  
◽  
Su Yean Teh ◽  
Hock Lye Koh
Keyword(s):  
Mathematical Model ◽  
Bifurcation Analysis ◽  
Water Hyacinth ◽  
Lake Restoration ◽  
Regime Shift ◽  
Oxygen Demand ◽  
Tropical Lakes ◽  
Ecosystem Structure ◽  
Flushing Rate ◽  
Long Duration

Regime shift is characterized by large, abrupt and persistent changes in ecosystem structure and dynamics. Bifurcation analysis is commonly used to identify regime shift equilibrium states and to distinguish their stability characteristics. Eutrophication in lake, a regime shift from clear-water oligotrophic state, is a stable equilibrium state that can persist for long duration. Characterized by undesirable turbid water condition, eutrophication has been known to impair valuable ecosystem services provided by lakes worldwide. The high incidence of eutrophication in Malaysian lakes (62%) mandates urgent need for lake restoration. The three-fold objectives of this paper are (1) to develop a mathematical model for analysing bifurcation criteria in regime shift, (2) to identify regime shift thresholds and (3) to propose effective ecosystem management strategy for shallow tropical lakes such as Tasik Harapan. A mathematical model consisting of four compartments: algae, phosphorus, dissolved oxygen and biochemical oxygen demand is formulated to analyse the eutrophication dynamics in the highly eutrophic Tasik Harapan (TH), a small shallow lake in Universiti Sains Malaysia (USM). Bifurcation analysis is performed by means of XPPAUT to identify the regime shift thresholds and to determine the type of lake response. Identified as irreversible, the eutrophication state of TH mandates an urgent lake restoration program to remove nutrients in the lake. Two restoration methods for reducing nutrients are assessed: (1) flushing of lake water and (2) hypothetical application of the invasive water hyacinth. Bifurcation analysis indicates that a flushing rate exceeding 0.042 day-1 is needed to restore TH to oligotrophic state. A complicated strategy of water hyacinth application would reduce the algae concentration from 300 μg/l to 120 μg/l after 9.6 years. A severe shortfall is the complicated and uncertain process of frequent removal of water hyacinth to prevent the lake from being overwhelmed by the invasive plants. The feasibility and sustainability of these two lake restoration methods are discussed. The insights gained would be useful to the relevant authorities in determining and implementing the best remediation measures for TH.

Study on Water Quality Improvement of Streams in Baoan District, Shenzhen City, China

2011 ◽  
Vol 347-353 ◽  
pp. 1902-1905
Author(s):  
Hua Li You
Keyword(s):  
Waste Water ◽  
Mathematical Model ◽  
Water Quality ◽  
Fresh Water ◽  
Water Discharge ◽  
Water Environment ◽  
Oxygen Demand ◽  
Polluted Water ◽  
Integrated Analysis ◽  
Shenzhen City

Water is the basis of natural resources and strategic economic resources.Deteriorated water environment of streams in Shenzhen city could have a great impact on ecological safety, people's health,and economic development.Based on the data of field observation and Remote sensing (RS) image,integrated analysis of the water degradation causes,and the changes of biochemical oxygen demand in five days(BOD5）concentration by mathematical model were carried out,which is on basis of percentage of waste water disposal,fresh water transformation,and harbor excavation, respectively.The results show that degradation causes of water quality were resulted from waste water discharge, harbor construction,and ecological environment damage, which could lead to slowly water exchange. Accordingly,the pollution can be easily to store in the bay,which result in water quality changes.The most important improved countermeasure is the control of waste water, which could be had a great effectiveness to decrease pollution.In addition, fresh water must be supplied after polluted water was cut off,which can be better improvement for water quality.This would be extreme improvement for hydrological dynamics due to 15m harbor excavation,which can significantly reduce BOD5 concentration.The innovation points of this paper is to mathematical model,which is based on the basis of qualitative analysis.

Biofuel production from bio-waste by biological and physical conversion processes

2019 ◽  
Vol 38 (1) ◽  
pp. 69-77
Author(s):  
Noppawan Photong ◽  
Jaruwan Wongthanate
Keyword(s):  
Water Hyacinth ◽  
Oxygen Demand ◽  
Cassava Starch ◽  
Biofuel Production ◽  
Conversion Process ◽  
Electricity Production ◽  
Biological Conversion ◽  
Initial Ph ◽  
Biomethane Production ◽  
Product Standard

This research is focused on the feasibility of biofuel from water hyacinth mixed with cassava starch sediment by biological and physical conversion processes and the comparison of the gross electricity production in these processes. The biological conversion process produced biomethane by anaerobic digestion. The optimal conditions of biomethane production were a ratio of water hyacinth and cassava starch sediment at 25:75, initial pH of 7.5, thermophilic temperature (55 ± 2°C) and C/N ratio of 30. The maximum biomethane yield measured was 436.82 mL CH4 g chemical oxygen demand (COD)−1 and the maximum COD removal was 87.40%. The physical conversion process was bio-briquette. It was found that the ratios of water hyacinth and cassava starch sediment at 10:90, 20:80, 30:70, 40:60 and 50:50 were the best ratio of fuel properties and close to the Thai Community Product Standard, with heating values of 15.66, 15.43, 15.10, 14.88 and 14.58 MJ kg−1, respectively. Moreover, results showed that the gross electricity production of the biological conversion process (biomethane) was 3.90 kWh and the gross electricity production of the physical conversion process (bio-briquette) from the ratios of water hyacinth and cassava starch sediment at 10:90, 20:80, 30:70, 40:60 and 50:50 were 1.52, 1.50, 1.47, 1.45 and 1.42 kWh, respectively.

scholarly journals Suitability of Macrophytes for Wastewater Treatment and Biogas Generation

2019 ◽  
Vol 9 (2S2) ◽  
pp. 16-18
Keyword(s):  
Wastewater Treatment ◽  
Water Hyacinth ◽  
Aquatic Macrophytes ◽  
Aquatic Macrophyte ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Cow Dung ◽  
Water Lettuce ◽  
Before And After ◽  
Almost All

In this paper three sustainable approaches are made in waste management option. Firstly primary treated domestic sewage is treated by aquatic macrophytes using duckweed, water hyacinth and water lettuce. Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Phosphate, Nitrates are tested before and after. Result indicates in terms of water quality, almost all three plants shows same removal efficiencies. BOD and TSS removal efficiency is attained more than 95%. COD and TDS removal is reached upto 50% for almost all plants. Secondly the used aquatic macrophytes for wastewater treatment is again used for generation of biogas (water lettuce unit, duckweed unit, water lettuce unit). In addition to three aquatic macrophytes, sludge is collected from aquatic macrophyte unit for generation of biogas. Comparison is made with conventional cow dung biogas unit. Result indicates water lettuce and duckweed produce biogas at earlier stage itself and water hyacinth takes some time for starting of biogas production. This may be due to the structure and texture causes some time for decomposition. Sludge gives maximum biogas generation among all experimental setup. Also in this study cow dung did not give biogas more may be due to poor blend ratio of cow dung with water is one of the reason.

scholarly journals The mathematical stability study for the system of the CoO(OH) – overoxidized polypyrrole composite synthesis in the presence of fluor ions

2016 ◽  
Vol 16 ◽  
pp. 13-17
Author(s):  
V. Tkach ◽  
S.C. De Oliveira ◽  
R. Ojani ◽  
P.I. Yagodynets ◽  
U. Páramo-García
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Bifurcation Analysis ◽  
Stability Theory ◽  
Stability Study ◽  
Linear Stability Theory ◽  
Monotonic Instability ◽  
Overoxidized Polypyrrole ◽  
Polypyrrole Composite ◽  
Steady State Stability

The potentiostatic synthesis of CoO(OH) – Overoxidized polypyrrole composite in the presence of fluor ions has been investigated mathematically. The corresponding mathematical model was described and analyzed by means of linear stability theory and bifurcation analysis. The steady-state stability requirements, like also oscillatory and monotonic instability conditions are derived.Mongolian Journal of Chemistry 16 (42), 2015, 13-17

scholarly journals Theoretical Description for Chlorantraniliprole Electrochemical Determination, Assisted by Squaraine Dye Nano Ag2O2 Composite

2020 ◽  
Vol 11 (2) ◽  
pp. 9278-9284
Keyword(s):  
Mathematical Model ◽  
Reaction Mechanism ◽  
Bifurcation Analysis ◽  
Electrochemical Determination ◽  
Theoretical Description ◽  
The Other ◽  
Linear Stability Theory ◽  
Oxide Nanoparticles ◽  
Monotonic Instability ◽  
Squaraine Dye

The theoretical description for the chlorantraniliprole electrochemical determination, assisted by the hybrid composite of squaraine dye with Ag2O2 nanoparticles, has been described. The correspondent reaction mechanism has been proposed, and the correspondent mathematical model has been developed and analyzed by means of linear stability theory and bifurcation analysis. It has been shown that the chlorantraniliprole electrochemical anodic determination on high potential may be efficiently provided by silver (I, III) oxide nanoparticles, stabilized by the squaraine dye. On the other hand, the oscillatory and monotonic instability is also possible, being caused by DEL influences of the electrochemical stage.

scholarly journals Bifurcation analysis of a mathematical model of atopic dermatitis to determine patient-specific effects of treatments on dynamic phenotypes

2018 ◽  
Vol 448 ◽  
pp. 66-79 ◽  
Author(s):  
Gouhei Tanaka ◽  
Elisa Domínguez-Hüttinger ◽  
Panayiotis Christodoulides ◽  
Kazuyuki Aihara ◽  
Reiko J. Tanaka
Keyword(s):  
Mathematical Model ◽  
Atopic Dermatitis ◽  
Bifurcation Analysis ◽  
Patient Specific ◽  
Specific Effects

Bifurcation Analysis of a Model Accounting for the 14-3-3s Signalling Compartmentalisation

2012 ◽  
pp. 61-70
Author(s):  
S. Nikolov ◽  
J. Vera ◽  
O. Wolkenhauer
Keyword(s):  
Mathematical Model ◽  
Cell Cycle ◽  
Phase Portrait ◽  
Bifurcation Analysis ◽  
Subcellular Localisation ◽  
Loss Of Stability ◽  
Cycle Arrest ◽  
Reversible Loss ◽  
Analytical Tools

Bifurcation theory studies the qualitative changes in the phase portrait when we vary the parameters of the system. In this book chapter we adapt and extend a mathematical model accounting for the subcellular localisation of 14-3-3s, a protein involved in cell cycle arrest and the regulation of apoptosis. The model is analysed with analytical tools coming from Lyapunov-Andronov theory, and our analytical calculations predict that soft (reversible) loss of stability takes place.

scholarly journals Identification of an Age Maturity in Time Discrimination Abilities

2020 ◽  
pp. 1-21 ◽  
Author(s):  
Quentin Hallez ◽  
Sylvie Droit-Volet
Keyword(s):  
Mathematical Model ◽  
Individual Variability ◽  
Bisection Task ◽  
Time Discrimination ◽  
Temporal Bisection ◽  
Time Sensitivity ◽  
Long Duration ◽  
Two Samples ◽  
Temporal Bisection Task ◽  
Weber Ratio

The aim of this study was to identify the age at which parameters of timing performance in a temporal bisection task converge on an adult-like stable level. Participants in the three- to 20-year-old range were tested using a temporal bisection task with sub-second and supra-second durations. The data were divided into two samples. In the first sample, all participants were integrated into the analysis regardless of their success. In the second sample, only performers were inserted. The point of subjective equality (PSE) and the Weber Ratio (WR) were analyzed for each participant in each sample. By fitting a mathematical model to these parameters as a function of age, we showed a large inter-individual variability in the PSE, such that it does not stabilize with increasing age, i.e., during the significant period of development. Interestingly, time sensitivity (WR) shows a similar pattern through the two samples as adult-like performance appeared at an earlier age for short than for long durations. For the first sample, the modeling of WR data suggests that the children reached an adult-like time sensitivity at the age of six years for the short durations and 8½ years for the long durations. For the second sample, the developmental curve was stable at about the same age for the long duration (seven years), and at earlier age for the short durations, i.e., before three years.

Bifurcation Analysis of a Mathematical Model for Malaria Transmission

2006 ◽  
Vol 67 (1) ◽  
pp. 24-45 ◽  
Author(s):  
Nakul Chitnis ◽  
J. M. Cushing ◽  
J. M. Hyman
Keyword(s):  
Mathematical Model ◽  
Malaria Transmission ◽  
Bifurcation Analysis
Sign in / Sign up

Export Citation Format

Share Document