A primary influence vertex approach to identify driving factors in complex integrated agri-industrial systems – an example from sugarcane supply and processing systems

Integrated agri-industrial systems (IAISs), such as sugarcane supply and processing systems, are complex systems and hence generally difficult to understand and manage. The large number factors in IAISs coupled with the complex interrelationships among the factors make it challenging to identify the points of intervention for improving their overall performance. Several approaches, such as the network theory and the Theory of Constraints have been used to identify important factors in systems with variations in success. This paper demonstrates a primary influence vertex approach for identifying and ranking the factors that drive the performance of IAISs. The approach is based on comprehensive causal network analyses and was tested in four relatively diverse large-scale sugarcane milling operations in South Africa. Results from the analyses were found to be consistent with the literature and external knowledge of the milling areas as at the time of the study. It is concluded that the approach can proffer a sound basis from which deeper rooted problems in systems can be identified on an ongoing basis. It is, however, recommended that the approach should be systematically compared with other relevant methods that are used to analyse complex systems.     

Voltage-controlled SAW filter on berlinite

An electrically tunable narrow-bandwidth SAW filter described. This new device works similarly as a SAW voltage controlled oscillator. Because of stability requirements ar recent availability, experiments are reported on berlini (AlPO4) crystal.     

Introduction to description of phase diagram of solid wüstite: I. Structural evidence of allotropic varieties

The stability field of solid wüstite has been the subject of many thermodynamic and structural investigations. These reveal three varieties - W₁, W₂ and W₃ - above 911°C and three other varieties - W′₁, W′₂ and W′₃ - below this temperature. A statistical analysis of our measurements, and of those found in recent literature, of the lattice parameter of wüstite as a function of composition and temperature confirms the existence of the three high-temperature varieties. A dilatometric study leads to the same conclusion. A similar analysis could be made for the three other varieties before studying their structure, but their existence has already been directly evidenced by thermogravimetric and structural investigations.     

Gases evolved from a high-methane coal using a Bleuler mill and mass spectrometry

Desorption of gases during the pulverizing of a coal in vacuum, air and oxygen for different periods has been studied. Results are discussed with reference to spontaneous combustion and other relevant factors.     

Contribution a l'etude du monoxyde de fer solide non-stoechiometrique. Diagramme T-P-X

A statistical numerical analysis from equilibrium thermogravimetric measurements obtained earlier by Raccah leads to describe a new T-p-x diagram of iron monoxide or wüstite. The external boundaries of the field of stable existence are precisely stated with the aid of some results from the literature. Three subphases W₁, W₂ and W₃ are revealed above 911°C; three others W′₁, W′₂ and W′₃ are revealed below 911°C, The related diagram shows their subfields. It shows also 23 invariant points between stable phases and 8 eventual invariant points between metastable phases. An almost complete bibliography of the work of Vallet's School about wüstite is given.     

A two-permeability approach for assessing flow properties in metal foam

One of the key properties for understanding the fluid flow and pressure drop in metal foam is the permeability. This paper investigates a non-traditional approach for evaluating this critical transport property by considering the physics of energy dissipation, i.e., the viscous dissipation and form drag and the fact that they are linked. The current work emphasizes the necessary initial step of clearly distinguishing between different flow regimes prior to evaluating the permeability. This distinction is usually either absent or overlooked in several previous studies, which may lead to significant errors. The approach presented in this study is applied to wind-tunnel steady-state unidirectional pressure-drop measurements for airflow through isotropic open-cell aluminum foam samples having different pore densities. The results show that the porous medium exhibits two different permeabilities—one is calculated and only valid in the Darcy regime, while the other is calculated and only valid in the Forchheimer regime.