MEASUREMENT AND EXPLANATION OF TECHNICAL EFFICIENCY IN MISSOURI HOG PRODUCTION

The U.S. live hog production has undergone a significant structural change characterized by a trend toward larger operations. Experts argue that there is a cost advantage for larger farms due to industrialization and increased management intensity. One important element in production, mainly for industries with rapid consolidation, is technical efficiency which affects the firm's competitive position directly. This study uses a stochastic production frontier function and farm-level data to measure and explain technical efficiency in Missouri hog production. The study estimates the mean technical efficiency for farms in the sample at about 82 percent, implying that a large proportion of production (18%) is lost due to farm-specific inefficiencies. Further, the results of the technical efficiency model proves the effects of technology and managerial skills on the level of productive efficiency. The study also finds economies of scale in hog production, thus explaining the consolidation in the industry.technical efficiency, economies of scale, production frontier, econometric methods, Industrial Organization, Livestock Production/Industries, Productivity Analysis,

Non-destructive quality control of carbon anodes using modal analysis, acousto-ultrasonic and latent variable methods

La performance des cuves d’électrolyse utilisées dans la production d’aluminium primaire par le procédé Hall-Héroult est fortement influencée par la qualité des anodes de carbone. Celles-ci sont de plus en plus variables en raison de la qualité décroissante des matières premières (coke et braie) et des changements de fournisseurs qui deviennent de plus en plus fréquents afin de réduire le coût d’achat et de rencontrer les spécifications des usines. En effet, les défauts des anodes, tels les fissures, les pores et les hétérogénéités, causés par cette variabilité, doivent être détectés le plus tôt possible afin d’éviter d’utiliser des anodes défectueuses dans les cuves et/ou d’apporter des ajustements au niveau du procédé de fabrication des anodes. Cependant, les fabricants d’anodes ne sont pas préparés pour réagir à cette situation afin de maintenir une qualité d'anode stable. Par conséquent, il devient prioritaire de développer des techniques permettant d’inspecter le volume complet de chaque anode individuelle afin d’améliorer le contrôle de la qualité des anodes et de compenser la variabilité provenant des matières premières. Un système d’inspection basé sur les techniques d’analyse modale et d’acousto-ultrasonique est proposé pour contrôler la qualité des anodes de manière rapide et non destructive. Les données massives (modes de vibration et signaux acoustiques) ont été analysées à l'aide de méthodes statistiques à variables latentes, telles que l'Analyse en Composantes Principales (ACP) et la Projection sur les Structures Latentes (PSL), afin de regrouper les anodes testées en fonction de leurs signatures vibratoires et acousto-ultrasoniques. Le système d'inspection a été premièrement investigué sur des tranches d'anodes industrielles et ensuite testé sur plusieurs anodes pleine grandeur produites sous différentes conditions à l’usine de Alcoa Deschambault au Québec (ADQ). La méthode proposée a permis de distinguer les anodes saines de celles contenant des défauts ainsi que d’identifier le type et la sévérité des défauts, et de les localiser. La méthode acousto-ultrasonique a été validée qualitativement par la tomographie à rayon-X, pour les analyses des tranches d’anodes. Pour les tests réalisés sur les blocs d’anode, la validation a été réalisée au moyen de photos recueillies après avoir coupé certaines anodes parmi celles testées.The performance of the Hall-Héroult electrolysis reduction process used for the industrial aluminium smelting is strongly influenced by the quality of carbon anodes, particularly by the presence of defects in their internal structure, such as cracks, pores and heterogeneities. This is partly due to the decreasing quality and increasing variability of the raw materials available on the market as well as the frequent suppliers changes made in order to meet the smelter’s specifications and to reduce purchasing costs. However, the anode producers are not prepared to cope with these variations and in order to maintain consistent anode quality. Consequently, it becomes a priority to develop alternative methods for inspecting each anode block to improve quality control and maintain consistent anode quality in spite of the variability of incoming raw materials.A rapid and non-destructive inspection system for anode quality control is proposed based on modal analysis and acousto-ultrasonic techniques. The large set of vibration and acousto-ultrasonic data collected from baked anode materials was analyzed using multivariate latent variable methods, such as Principal Component Analysis (PCA) and Partial Least Squares (PLS), in order to cluster the tested anodes based on vibration and their acousto-ultrasonic signatures. The inspection system was investigated first using slices collected from industrial anodes and then on several full size anodes produced under different conditions at the Alcoa Deschambault in Québec (ADQ). It is shown that the proposed method allows discriminating defect-free anodes from those containing various types of defects. In addition, the acousto-ultrasonic features obtained in different frequency ranges were found to be sensitive to the defects severities and were able to locate them in anode blocks. The acousto-ultrasonic method was validated qualitatively using X-ray computed tomography, when studying the anode slices. The results obtained on the full size anode blocks were validated by means of images collected after cutting some tested anodes

Polinomno analitičko rješenje za jednobrzinsko razlaženje neutrona u sloju uz provjereno sadržane Mark-Marshakove granične uvjete

Boubaker polynomials are used to obtain analytical solutions to the one-speed neutron transport equation for strongly anisotropic scattering. The main advantage of the method lies in proposing solution terms which verify inherent symmetry and Mark-Marshak boundary conditions prior to resolution process. This original feature results in convergent and accurate solutions. Boubaker polynomials expansion scheme is further applied to homogeneous slab problem with strongly anisotropic scattering and vacuum boundaries. Parallel to the classical formulation, the kernels for scattered and fission neutrons are originally chosen on the basis of most realistic models. The results, expressed in terms of linear extrapolation distance de, are recorded and compared to those presented in the related literature.Primjenjuju se Boubakerovi polinomi za dobivanje analitičkog rješenja jednadžbe za razlaženje neutrona jedne brzine pri jako anizotropnom raspršenju. Osnovna prednost metode sastoji se u traženju rješenja preko članova koji provjeravaju unutarnju simetriju i Mark-Marshakove granične uvjete prije postupka razvoja. Ta izvorna odlika vodi na konvregentna i točna rješenja. Boubakerova se polinomna shema razvoja zatim primjenjuje na problem jednolikog sloja s jako neizotropnim raspršenjem i granicama s vakuumom. Usporedo s klasičnim predstavljanjem, jezgre za raspršene i diobene neutrone se izvorno odabiru na osnovi najstvarnijih modela. Ishodi računa, izraženi preko linearne ekstrapolacijske duljine de, prikazuju se i uspoređuju s objavljenima

Polinomno analitičko rješenje za jednobrzinsko razlaženje neutrona u sloju uz provjereno sadržane Mark-Marshakove granične uvjete

Boubaker polynomials are used to obtain analytical solutions to the one-speed neutron transport equation for strongly anisotropic scattering. The main advantage of the method lies in proposing solution terms which verify inherent symmetry and Mark-Marshak boundary conditions prior to resolution process. This original feature results in convergent and accurate solutions. Boubaker polynomials expansion scheme is further applied to homogeneous slab problem with strongly anisotropic scattering and vacuum boundaries. Parallel to the classical formulation, the kernels for scattered and fission neutrons are originally chosen on the basis of most realistic models. The results, expressed in terms of linear extrapolation distance de, are recorded and compared to those presented in the related literature.Primjenjuju se Boubakerovi polinomi za dobivanje analitičkog rješenja jednadžbe za razlaženje neutrona jedne brzine pri jako anizotropnom raspršenju. Osnovna prednost metode sastoji se u traženju rješenja preko članova koji provjeravaju unutarnju simetriju i Mark-Marshakove granične uvjete prije postupka razvoja. Ta izvorna odlika vodi na konvregentna i točna rješenja. Boubakerova se polinomna shema razvoja zatim primjenjuje na problem jednolikog sloja s jako neizotropnim raspršenjem i granicama s vakuumom. Usporedo s klasičnim predstavljanjem, jezgre za raspršene i diobene neutrone se izvorno odabiru na osnovi najstvarnijih modela. Ishodi računa, izraženi preko linearne ekstrapolacijske duljine de, prikazuju se i uspoređuju s objavljenima

Date Palm Value Chain Analysis and Marketing Opportunities for the Gulf Cooperation Council (GCC) Countries

In order to develop a sustainable date palm production system in the Gulf Cooperation Council (GCC) countries of the Arabian Peninsula, an analysis of the date value chain in these countries was undertaken. Through the mapping of the chain, the overall objective was to identify the processes where values are created and how they are distributed among stakeholders along the entire date palm value chain. The method used in this analysis was based on an assessment of the data gathered from the multi-stakeholder surveys implemented in the three case studies of the GCC countries: Kingdom of Saudi Arabia (KSA), Oman, and Kuwait. The empirical findings reveal several problems and constraints that might affect the future of the GCC date palm sector. Therefore, development of a competitive supply date palm chain (both market and agribusiness development) could provide a greater contribution to the GCC economy if producers paid more attention to marketing of this very important food commodity. Hence, date palm production is no longer a way of life but nowadays is considered as an investment option and source of revenues for many stakeholders if the GCC region