Using Google Trends to assess the impact of Global Public Health Days on online health information-seeking behaviour in Arabian Peninsula.

BACKGROUND: Global Public Health Days (GPHD) are public health interventions which serve to improve public awareness of specific health conditions. Google Trends is a publicly available tool that allows the user to view the popularity of a searched keyword during a specified time period and across a predetermined region. Our objective was to use Google Trends to assess the impact of four GPHD (World Heart Day, World Mental Health Day, World Diabetes Day and World Hypertension Day) on online health information-seeking behaviour (OHISB), 4 weeks before and a week after the GPHD, across six countries of the Arabian Peninsula (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and United Arab Emirates). METHODS: Relative Search Volume (RSV) was extracted for the aforementioned countries from 28 days before the GPHD and 7 days afterwards. Statistical analysis, undertaken using joinpoint regression software, showed that GPHD have significant changes for Saudi Arabia (Diabetes, Mental Health and Heart day) and UAE (Mental Health day) but were short-lived with a fall in RSV of up to 80% after peak interest. CONCLUSION: GPHD appears to be effective in some countries while further research is needed to investigate the reason of its limitations

Robust control of industrial multi-stage flash desalination plants

The paper investigates the use of non-linear model predictive control (NLMPC) as an advanced control strategy for the control of multi-stage flash (MSF) desalination plants. For this purpose, a comprehensive non-linear dynamic model was developed for the MSF plant and was validated with actual plant data. A control structure for the plant was then developed from which two control objectives were selected. One control objective is to maximize the distillate product and the other is to maximize the performance ratio while maintaining the manipulated variables in both cases under tight hard constraints. The NLMPC algorithm was then tested with these two objectives for both nominal and non-nominal model cases. In the non-nominal case the effects of parametric modeling error on the NLMPC performance were examined. Closed-loop simulations show that the advanced control strategy allows good control performance and substantial energy savings even when the plant is under the influence of unavoidable model uncertainties. The performances of the NLMPC algorithm were compared with a conventional proportional-integral (PI) controller

Classification of static and dynamic behavior in a fluidized-bed catalytic reactor

The singularity theory and continuation techniques are combined to classify the static and dynamic behavior of a non-isothermal gas-solid fluidized-bed catalytic reactor with consecutive exothermic reactions A→k1B→k2C. It is shown that the double limit variety with five solutions is the highest static singularity the model can predict. The model is also capable of predicting self sustained oscillations for a wide range of Lewis numbers. The effect of the model parameters on its static and dynamic bifurcation is analyzed. Practical criteria are also derived for the effect of the branching phenomena on the yield of the intermediate product in the reactions network

Hydrodynamics of gas fluidized beds with mixture of group D and B particles

The dynamics of a gas-solid fluidized bed containing Geldart Group D particles mixed with a small proportion of Geldart Group B particles are investigated using pressure fluctuations data. Time series analysis, using a variety of nonlinear dynamics tools, shows that the slugging present with Group D particles can be suppressed by the addition of a small proportion of Group B particles. The power spectra and the auto-correlation function are used for a preliminary evaluation of dominant slug frequencies. It is shown that the bed fluidized with the mixture of Group D and B particles behaves in a less periodic manner and is dominated by more random bubble motion. On the other hand, the correlation integral is used to analyze the chaotic behaviour of the flow, through evaluation of the fractal structure of the reconstructed attractors. It is shown that the bed fluidized with Group D particles is characterized by a combination of steady slug motion and irregular particles motion. The behaviour of the fluidized bed of Group D/B particles mixture is characterized by a single correlation dimension for a wide range of fluidization velocities