Application of a primal-dual interior point algorithm using exact second order information with a novel non-monotone line search method to generally constrained minimax optimization problems

This work presents the application of a primal-dual interior point method to minimax optimisation problems. The algorithm differs significantly from previous approaches as it involves a novel non-monotone line search procedure, which is based on the use of standard penalty methods as the merit function used for line search. The crucial novel concept is the discretisation of the penalty parameter used over a finite range of orders of magnitude and the provision of a memory list for each such order. An implementation within a logarithmic barrier algorithm for bounds handling is presented with capabilities for large scale application. Case studies presented demonstrate the capabilities of the proposed methodology, which relies on the reformulation of minimax models into standard nonlinear optimisation models. Some previously reported case studies from the open literature have been solved, and with significantly better optimal solutions identified. We believe that the nature of the non-monotone line search scheme allows the search procedure to escape from local minima, hence the encouraging results obtained

Potential of using bio-coagulants indigenous to Malaysia for surface water clarification

Water treatment processes in developing countries typically include coagulation and flocculation and often use alum as the coagulant. Coagulation is a critical step in drinking water treatment because of removing the colloidal particles as well as pathogens that are often attached to the particles. However, the cost of the imported chemicals in hard currency has caused to consider the natural coagulants as a promising alternative. In the present study, turbidity removal of Moringa oleifera, Jatropha curcas, chitosan, dragon fruit foliage and alum were compared using surface turbid water. The efficacy of four bio-coagulants has been tested based on some critical parameters including dosages of coagulant, pH of turbid water and change in pH value of finished water. All studied coagulants obviously possessed positive coagulation abilities

Ion-exchange adsorption of reactive dye solution onto quaternized palm kernel shell

Quaternized palm kernel shell was successfully prepared by reacting with N-(3-chloro-2-hydroxypropyl)trimethylammonium chloride in basic condition. Adsorption experiments of Reactive Red E (RRE) dye were carried out in single batch system studied at various initial concentration, contact time and pH at 25°C. It was found that at pH 4 quaternized palm kernel shell showed the highest dye removal percentage of 99% at 100 mg L-1 initial dye concentration. The equilibrium data were analyzed by Langmuir, Freundlich and Redlich-Peterson models and Redlich-Peterson model was best fit to describe this adsorption. Contact time data were analyzed using pseudo-first-order and pseudo-second-order kinetic models and was found that the kinetics conformed pseudo-second-order kinetic model. The maximum adsorption capacity of RRE was 183 mg g-1 for single batch system

Dynamic optimization for controller tuning with embedded safety and response quality measures

Controller tuning is needed to select the optimum response for the controlled process. This work presents a new tuning procedure of PID controllers with safety and response quality measures on a non-linear process model by optimization procedure, with a demonstration of two tanks in series. The model was developed to include safety constraints in the form of path constraints. The model was then solved with a new optimization solver, NLPOPT1, which uses a primal-dual interior point method with a novel non-monotone line search procedure with discretized penalty parameters. This procedure generated a grid of optimal PID tuning parameters for various switching of steady-states to be used as a predictor of PID tunings for arbitrary transitions. The interpolation of tuning parameters between the available parameters was found to be capable to produce state profiles with no violation on the safety measures, while maintaining the quality of the solution with the final set points targeted achievable

An overview on convergence acceleration of cyclic adsorption processes

Cyclic adsorption processes are inherently dynamic where the process variables are always varying with time. The cyclic processes have no steady state. Thousands of repeated cycles may be needed before cyclic steady state (CSS) is reached. In this paper, the basic concept and characteristics of cyclic adsorption processes are first introduced, using air separation by rapid pressure swing adsorption as an example. Next, different approaches to calculate and accelerate the convergence of CSS are briefly reviewed. The computational time can be reduced by having an efficient discretisation technique and accelerators to achieve the final CSS. Hybrid methods are potentially attractive

A preliminary study on Jatropha curcas as coagulant in wastewater treatment

Many coagulants, mainly inorganic, are widely used in conventional water and wastewater treatment. Recent studies reported the occurrence of some chronic diseases associated with residual coagulant in treated wastewater. The use of alternative coagulants which are biodegradable and environmentally friendly could alleviate the problem associated with these diseases. This work investigates the capability of Jatropha curcas seed and presscake (the residue left after oil extraction) to reduce the turbidity of wastewater through coagulation. The coagulant was prepared by dissolving Jatropha curcas seed and presscake powder into solution. Then jar tests were conducted on kaolin solution as the model wastewater. The Jatropha seed was found to be an effective coagulant with more than 96% of turbidity removal at pH 1–3 and pH 11–12. The highest turbidity removal was recorded at pH 3 using a dosage of 120 mg/L. The flocs formed using Jatropha were observed to be bigger and to sediment faster when compared with flocs formed using alum. The turbidity removal was high (>98%) at all turbidities (100 NTU to 8000 NTU), suggesting its suitability for a wide range of industrial wastewater. The performance of Jatropha presscake after extraction of oil was also comparable to the fresh seed and alum at highly acidic and highly alkaline conditions. The addition of Jatropha did not significantly affect the pH of the kaolin samples after treatment and the sludge volume produced was less in comparison to alum. These results strongly support the use of Jatropha curcas seed and presscake as a potential coagulant agent

Hybrid algorithm for acceleration of convergence to cyclic steady state

Cyclic process is inherently dynamic, thus it has no steady state. However, the process, after a sufficient number of cycles, will reach a state called Cyclic Steady State (CSS) where the process state variables at some instant within a cycle have the same value at the corresponding instant within each subsequent cycle. Depending on the nature of the cyclic process, the number of cycles needed before the process reaches CSS may vary from tens to thousands. In this study, a hybrid algorithm that aims to predict and accelerate the convergence of the CSS is developed and tested on a cyclic operation of controlled-cycled stirred tank reactor

Development of novel low-cost quaternized adsorbent from palm oil agriculture waste for reactive dye removal

An attempt was made to chemically modify palm kernel shell (MPKS) to increase adsorption affinity towards Reactive Black 5 (RB5). Granulated palm kernel shell (PKS) was quaternized successfully by treating with N-(3-chloro-2-hydroxypropyl)trimethylammonium chloride under alkaline conditions and was characterized. Surface characterization by Scanning Electron Microscopy (SEM) and BET analysis confirmed the surface pore enlargement from mesospores to macropores after modification. Fourier Transform-Infrared (FTIR) Spectrometer and CHN analysis revealed that the quaternary ammonia group (NR4+) was successfully reacted on MPKS fiber. pH 4 is the optimum for removal of RB5 on MPKS. Equilibrium isotherms were analyzed by the Langmuir, Freundlich, and Redlich-Peterson models. The Redlich-Peterson model was found to fit well with the data. The maximum adsorption capacity of MPKS was 207.5 mg/g for adsorption of RB5

Low temperature growth of vertically aligned carbon nanotubes via floating catalyst chemical vapor deposition method.

Synthesis of carbon nanotubes (CNTs) below 600°C using supporting catalyst chemical vapor deposition method was reported by many research groups. However, the floating catalyst chemical vapor deposition received less attention due to imperfect nanotubes produced. In this work, the effects of varying the preheating temperature on the synthesis of CNT were investigated. The reaction temperature was set at 570°C. The preheating set temperature was varied from 150 to 400°C at 50°C interval. Three O-ring shape heating mantels were used as heating source for the preheater. In situ monitoring device was used to observe the temperature profile in the reactor. Benzene and ferrocene were used as the carbon source and catalyst precursor, respectively. Vertically aligned CNTs were synthesized when the preheating temperature was set at 400°C. When the preheating temperature was increased up to 400°C, both the length and the alignment of CNTs produced were improved

Effect of storage of shelled Moringa oleifera seeds from reaping time on turbidity removal

Moringa oleifera is an indigenous plant to Malaysia whose seeds are used for water purification. Many studies on Moringa oleifera have shown that it is highly effective as a natural coagulant for turbidity removal. In this study, two different methods for extraction of Moringa's active ingredient were investigated. Results of sodium chloride (NaCl) and distilled water extraction of Moringa oleifera seeds showed that salt solution extraction was more efficient than distilled water in extracting Moringa's active coagulant ingredient. The optimum dosage of shelled Moringa oleifera seeds extracted by the NaCl solution was comparable with that of the conventional chemical coagulant alum. Moreover, the turbidity removal efficiency was investigated for shelled Moringa oleifera seeds before drying in the oven under different storage conditions (i.e. open and closed containers at room temperature, 27 °C) and durations (fresh, and storage for 2, 4, 6 and 8 weeks from the time the seeds were picked from the trees). Our results indicate that there are no significant differences in coagulation efficiencies and, accordingly, turbidity removals between the examined storage conditions and periods