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Abstract: In this study, for the first time we demonstrated that both random and chain‐end scissions of polymers can be simulated on a unified Fixed Pivot (FP) framework through an elegant implementation of a discrete‐continuous meshing strategy. Achieved using only a fraction of computational expense in solving the full set of exact equations, the FP solutions benchmarked very well against the exact solutions for a polymer with a broad size distribution typical of natural polymers at different degrees of up to ∼O(105). This is attained despite the use of an efficient computational technique to obtain the exact solutions. Moreover, new observations revealed an additional strength of the current meshing strategy, in that the number of the discrete partitions can be adjusted to improve the accuracy of the solution while retaining the total number of equations to be solved. The FP technique, which in the past was reported to over‐predict in cases of pure aggregation, also exhibits marginal over‐prediction for pure random scission. The source of this behaviour is further uncovered, leading to a revised guideline on the choice of the number of discrete pivots. [ABSTRACT FROM AUTHOR]

BACKGROUND The focus of wastewater management has evolved from treatment technology into resource recovery, which enables simultaneous waste minimization and value-added product generation. This study utilized palm oil mill effluent ( POME) for volatile fatty acids ( VFA) production by acidogenic fermentation at mesophilic (30°C and 40°C) and thermophilic (55°C) temperatures. The viability of using the VFA produced to generate biodegradable plastics polyhydroxyalkanoates ( PHA) was also determined. RESULTS The VFA production at mesophilic temperature outperformed thermophilic temperature considerably, with a degree of acidification of 48% at both 30°C and 40°C but only 7% at 55°C. These results were in agreement with the substrate consumption profiles whereby the percentage of substrate consumption at 55°C was six times lower than those at 30°C and 40°C. The VFA produced from POME could be used for PHA production, achieving 17 wt% PHA of sludge dry weight. CONCLUSION Mesophilic acidogenic fermentation of POME is preferable due to its better VFA production. Since palm oil mills are located in tropical countries, the fermentation can be conducted under ambient conditions (25-32°C) and without temperature control. The potential of VFA-rich fermented POME for PHA production is recognized, but optimization of the PHA production conditions is required for higher PHA content. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A dualadaptation generalized predictive controller (DA-GPC) capableof synchronous modeling and tuning in real time is proposed. The distinctivefeature of the proposed controller is the utilization of a secondorder discrete time controlled auto-regressive integrated moving average(CARIMA) model to capture all possible variations of numerator dynamicsvia the variable forgetting factor recursive least squares (VFF-RLS)algorithm. The evolving dynamic model is then used to tune, in realtime, the value of the move suppression weight. Simulation studieson two benchmark process control problems, i.e., the Van de Vussenonlinear isothermal stirred tank reactor (with dead time) and thestrong acid–base neutralization process, revealed the improvedperformance of the DA-GPC scheme over the traditional model adaptiveGPC and the conventional GPC schemes in terms of set point tracking.Further simulation studies revealed that the DA-GPC scheme was adeptin rejecting load disturbances in the process. The good performanceattained was attributed to the judicious adaptation of the move suppressionweight. Moreover, a user-friendly aspect of the DA-GPC scheme is thatthe only parameter requiring manual tuning is the VFF-RLS parameter(σ), which may span a large range without materially affectingthe efficacy of this adaptive controller. [ABSTRACT FROM AUTHOR]

ABSTRACT A second look at biodiesel reactor control using Recursive Least Squares (RLS)-based adaptive Generalized Predictive Control (GPC) strategy revealed the possibility of a simpler alternative to the previously published centralized RLS-based GPC controller (CRLS-GPC). New results show that the simpler decentralized RLS-based GPC controller (DRLS-GPC) was on par with the more sophisticated centralized version in terms of servo and regulatory control, process interactions handling, and the resultant controller moves. Moreover, the simplified control scheme remained superior to the conventional Proportional-Integral controller. Such attributes make the DRLS-GPC an attractive compromise between complexity and performance. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]