Sorption,diffusion, and swelling characteristics of sodium alginate and its blend membranes with poly(vinyl alcohol) in water–acetic acid mixtures

Sorption, diffusion, and swelling characteristics of sodium alginate and its blend membranes with poly(vinyl alcohol) were investigated for water–acetic acid mixtures by using a gravimetric method at 30, 40, and 50°C. The membranes were characterized by X‐ray diffraction and Fourier transform infrared techniques. Concentration‐independent diffusion coefficients were obtained by applying Fick's relationship before completion of equilibrium sorption. Permeation coefficients were calculated from sorption and diffusion coefficients. Concentration profiles of liquids were computed considering the sheet geometry for the membrane by solving Fick's equation under suitable boundary conditions. Arrhenius activation parameters were computed for the transport processes. Experimental results and calculated quantities were discussed to understand membrane–solvent interactions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1139–1150, 2004     

Response surface methodology for optimization of growth parameters for the production of carotenoids by a mutant strain of Rhodotorula gracilis

Response surface methodological studies of growth parameters for carotenoid production by a mutant strain of Rhodotorula gracilis (CFR 0-1) was carried out by a two-level fractional factorial design involving five variables, namely glucose concentration (%), incubation period (days), volume of inoculum (ml/100 ml), pH, and temperature (°C). The response equation developed indicated linear relationship between period of incubation, temperature, sugar concentration, and volume of inoculum on carotenoid production. A temperature of 24 °C was found to exhibit maximum carotenoid production in the mutant. The results indicated maximum carotenogenesis (0.09%) at 8% glucose level, with pH 7.5 and 6.0 ml/100 ml of inoculum for an incubation period of 12 days at 24 °C, which was also verified by experimental data.     

Optimisation of growth parameters for the production of carotenoids by Rhodotorula gracilis

 Response surface methodological studies of growth parameters for carotenoid production by Rhodotorula gracilis (ATCC 90950) have been carried out for three parameters employed, namely glucose concentration (%), incubation period (days) and volume of inoculum (ml/100 ml). The results indicated maximum carotenogenesis (0.054%) at a 10% glucose level with a 2 ml/100 ml volume of inoculum for an incubation period of 9 days, which was also verified by experimental data. Received: 25 May 1998     

Single cell protein production from digested and undigested poultry litter by Candida utilis: optimization of process parameters using response surface methodology

In this study, production of single cell protein (SCP) was carried out using Candida utilis from undigested poultry litter (UPL) and digested poultry litter (DPL). UPL and DPL were hydrolyzed by acid hydrolysis initially and the resulting crude hydrolysates were used for SCP production. Fermentation variables of the production medium were optimized by single variables optimization methodology. By this conventional approach, SCP production from UPL and DPL has increased to 25 and 20 %, respectively. The proportional analysis of these results revealed that UPL was the suitable substrate than DPL for the production of SCP by C. utilis. Further, 2³ central composite design was applied to determine the optimal process parameters for SCP production using UPL as substrate. The analysis of treatment combinations showed that a second-order polynomial regression model was in good agreement with experimental results at R ² value ?0.98 (P < 0.05). These results suggest that UPL concentration was the most influential factor affecting the SCP production with a P value of 2.22E-09 followed by yeast extract and pH at 0.0339 and 0.0439, respectively. Based on contour plots, the optimum conditions for SCP production were found to be the UPL concentration—5.6 % w/v, yeast extract concentration—2.3 % w/v, and pH—7. After statistical optimization, SCP production by C. utilis strain has increased 29 %. It is understood from this study that UPL could be used effectively as substrate for the production of animal feed supplement with benefit of reducing feed cost as well as mitigating environmental problems associated with poultry litter.     

System Wide Data Quality Control of Inductance Loop Data Using Nonlinear Optimization

One of the main criticisms and concerns over the years about inductive loop detector (ILD) data is systematic errors in the data associated with noncatastrophic malfunctioning of the devices. Most of the current approaches check for ILD data accuracy at individual locations. However, for an end application that requires data from neighboring locations, such as for travel time or origin-destination estimation, data quality control at a system level is required. Under such system-level data quality control, one of the basic requirements is that the data should follow the conservation of vehicles principle. However, this fundamental requirement and the associated diagnostic methods for identifying violations of this constraint have received little attention in the transportation engineering literature. This paper presents a methodology for checking conservation of vehicles over a series of detectors and adjusting the data using a constrained nonlinear optimization approach whenever the conservation principle is violated. The generalized reduced gradient method is adopted and applied to a 2-mi test bed in San Antonio. The method is validated using simulated data generated with CORSIM simulation software.     

Travel time prediction under heterogeneous traffic conditions using global positioning system data from buses

Travel time information is a vital component of many intelligent transportation systems (ITS) applications. In recent years, the number of vehicles in India has increased tremendously, leading to severe traffic congestion and pollution in urban areas, particularly during peak periods. A desirable strategy to deal with such issues is to shift more people from personal vehicles to public transport by providing better service (comfort, convenience and so on). In this context, advanced public transportation systems (APTS) are one of the most important ITS applications, which can significantly improve the traffic situation in India. One such application will be to provide accurate information about bus arrivals to passengers, leading to reduced waiting times at bus stops. This needs a real-time data collection technique, a quick and reliable prediction technique to calculate the expected travel time based on real-time data and informing the passengers regarding the same. The scope of this study is to use global positioning system data collected from public transportation buses plying on urban roadways in the city of Chennai, India, to predict travel times under heterogeneous traffic conditions using an algorithm based on the Kalman filtering technique. The performance of the proposed algorithm is found to be promising and expected to be valuable in the development of APTS in India. The work presented here is one of the first attempts at real-time short-term prediction of travel time for ITS applications in Indian traffic conditions.