Flexible resources allocation techniques: characteristics and modelling

At the interface between engineering, economics, social sciences and humanities, industrial engineering aims to provide answers to various sectors of business problems. One of these problems is the adjustment between the workload needed by the work to be realised and the availability of the company resources. The objective of this work is to help to find a methodology for the allocation of flexible human resources in industrial activities planning and scheduling. This model takes into account two levers of flexibility, one related to the working time modulation, and the other to the varieties of tasks that can be performed by a given resource (multi–skilled actor). On the one hand, multi–skilled actors will help to guide the various choices of the allocation to appreciate the impact of these choices on the tasks durations. On the other hand, the working time modulation that allows actors to have a work planning varying according to the workload which the company has to face

Un modèle à évènements pour étudier la flexibilité opérationnelle d’un flow shop flexible

La gestion des ateliers de production recherche le meilleur compromis entre les impératifs commerciaux, financiers et industriels. L’objectif de cet article est la caractérisation et la modélisation des leviers de flexibilité d’un atelier de production à cheminement unique (« flow shop »), afin d’assurer la flexibilité opérationnelle du système. Cette flexibilité porte sur le fait que chaque poste de la chaîne de production dipose d’une ou plusieurs machines identiques, sur des durées opératoires variables à chaque poste selon le nombre des opérateurs affectés, et sur les dates de livraison des produits. La convergence entre les ressources requises pour l’exécution d’un plan de production et celles mises en œuvre pour sa réalisation est favorisée. La fonction objectif intègre l’évaluation des stocks et en-cours, le coût du travail et de l’inactivité, et les conséquences des perturbations. Le problème est résolu en traitant l’ensemble des variables simultanément, selon une formulation de programmation mathématique non-linéaire en variables mixtes (MINLP)

A greedy heuristic approach for the project scheduling with labour allocation problem

Responding to the growing need of generating a robust project scheduling, in this article we present a greedy algorithm to generate the project baseline schedule. The robustness achieved by integrating two dimensions of the human resources flexibilities. The first is the operators’ polyvalence, i.e. each operator has one or more secondary skill(s) beside his principal one, his mastering level being characterized by a factor we call “efficiency”. The second refers to the working time modulation, i.e. the workers have a flexible time-table that may vary on a daily or weekly basis respecting annualized working strategy. Moreover, the activity processing time is a non-increasing function of the number of workforce allocated to create it, also of their heterogynous working efficiencies. This modelling approach has led to a nonlinear optimization model with mixed variables. We present: the problem under study, the greedy algorithm used to solve it, and then results in comparison with those of the genetic algorithms

Study of some biological parameters of the oil palm tree leaf miner, Coelaenomenodera lameensis (Coleoptera: Chrysomelidae, Hispinae) in a semi-controlled environment

The oil palm tree is the first source of fatty substances of vegetable origin in the world. However, its cultivation is strongly threatened by damage from Coelaenomenodera lameensis. The present study aimed at promotion a good knowledge of its biology in order to better manage its populations. Thus, some biological parameters of this pest were studied by means of cage breeding (September 2015-December 2017) on an plot ofLa Mé station of National Agronomic Research Center located 30 km North-East of Abidjan in Côte d’Ivoire. The results revealed that the development of C. lameensis passes successively through stages egg, larva, nymph, internal adult and external adult stages. Also, the female lays an average of 137.48 ± 62.04 eggs and the number of individuals gradually decreases from egg stage to adult stage. The average life cycle length was 94.5 ± 7.94 days with a sex ratio of 1.34 ± 0.25 in favor of males. In addition, the mean lifespan was shorter in females than in males with respectively, 103.24 ± 10.25 days and 127.34 ± 21.41 days. All these parameters constitute potential indicators of C. lameensis biology and could help to put in place good strategies for control of its populations

Isolation of phytoplasma DNA from the coconut palms (Cocos nucifera L.) collected from Ghana

This study aimed to verify the presence of the causative agent of Lethal Yellowing which is phytoplasma in samples provided from infected coconut trees. Study was carried out by using various samples like zygotic embryo, young leaves and immature & mature inflorescences. These materials were collected from trees at the stage 1 and 2 of the disease development.. Stage 1 of disease development is characterized by leaf yellowing and the start of the falling nuts while at the stage 2 of disease development, the trees has not bear nuts longer. From infected material, DNA was extracted by three different processes and isolated DNA was amplified by PCR. 16S rRNA gene was amplified by two specific primers of phytoplama viz P1/P2 and Ghana 813/AKSR. Among the various tested materials presence of phytoplasma was reported from the mature inflorescences while the presence of the phytoplasma was not reported from the leaves and embryos of the coconut

Intégration de la polyvalence et de la modulation d'horaire dans une approche d'affectation flexible de la ressource humaine

Dans ce travail, nous proposons une démarche méthodologique en matière de planification d’activités industrielles, qui prend en compte deux aspects de la flexibilité, liés l’un à la possibilité que pourrait avoir une ressource humaine à exécuter diverses tâches (polyvalence) et la modulation du temps de travail. Comme tout problème d’affectation, nous avons d’une part, un programme à réaliser pour lequel nous supposons connues les tâches, leur ordonnancement prévisionnel ainsi que les charges par tâche et par compétence. Et d’autre part, nous considérons une entreprise chargée de mener à bien l’activité, et composée d’acteurs supposés polyvalents travaillant selon des horaires modulables. Pour caractériser la polyvalence, nous associons à chaque compétence des acteurs un poids que nous appelons dans notre modèle « efficacité », permettant d’abord de guider les divers choix d’affectation ; elle nous sert également à apprécier, les répercussions de ces choix sur les durées standards définies pour les tâches. Dans cet article, nous proposons un modèle mathématique qui décrit les différentes contraintes, la fonction « objectif » du problème et une démarche méthodologique qui nous permet de simuler différentes politiques d’affectation des ressources humaine

Prevalence Of African Giant Snails For Parasites In A South-East Region Of Côte d'Ivoire

Two species of snails (Achatina achatina and Archachatina ventricosa), from surrounding forest of Azaguié’s district, were collected at the market of the locality aforementioned in order to identify their various parasites. For that, 50 snails of each species were sacrificed. Parasites were searched on the level of the flesh, between the flesh and the shell, the stomach, the intestine, the liver and the reproductive apparatus. The collected parasites were Balantidium spp, the larvae of Protostrongylus spp, the larvae of Dicrocoelium spp and Trichomonas spp. Our results showed that 52% of Achatina achatina and 74% of Archachatina ventricosa were parasitized. Among the parasites collected in the snail Achatina achatina, 95.8% were nematodes and 4.1% were trematodes. Whereas in the snail Archachatina ventricosa, 97.7% were protozoa, 8.8% nematodes and 0.4% consisting with trematodes. The prevalence of Protostrongylus spp (48%) were higher than that of Dicrocoelium spp (4%) in Achatina achatina. For the snail Archachatina ventricosa, the prevalence of parasite were dominated by Trichomonas spp (38%) and Protostrongylus spp (24%)

Abondance des mouches des fruits dans les zones de production fruitières de Côte d'Ivoire : dynamique des populations de Bactrocera invadens (Diptera : Tephritidae)

Introduction. L'objectif de notre étude a été de recenser les différentes espèces de Tephritidae présentes sur arbres fruitiers dans trois régions climatiques différentes de Côte d'Ivoire et d'identifier quelques plantes hôtes auxquelles elles sont associées. Matériel et méthodes. Un dispositif de pièges utilisant différentes phéromones a été mis en place dans les régions agro écologiques du sud (Azaguié, Abidjan) et du centre (Yamoussoukro) de la Côte d'Ivoire entre juin 2005 et septembre 2006. En complément, une collecte de fruits a été effectuée dans ces mêmes régions ainsi qu'au nord du pays (Korhogo). La fluctuation de la population de Bactrocera invadens a été suivie à partir de relevés hebdomadaires des pièges. Les mouches émergées des fruits collectés ont été identifiées et comptées. Résultats et discussion. Au total, 23 espèces de mouches des fruits ont été identifiées dont huit espèces particulières à Azaguié, une espèce à Abidjan et une espèce à Yamoussoukro. Les espèces B. invadens et D. mediovittatus ont été identifiées pour la première fois en Côte d'Ivoire. L'espèce B. invadens s'est révélée majoritaire sur les stations du sud et du centre de la Côte d'Ivoire. Elle est représentée à 85 % à Azaguié, à 99,90 % à Abidjan et à 95,40 % à Yamoussoukro. Le méthyl eugénol et le dorsalure ont été les plus efficaces pour capturer un grand nombre d'individus. Les genres Ceratitis et Dacus, bien que présentant une diversité spécifique, sont faiblement représentés sur les sites expérimentaux étudiés. Selon les zones agro écologiques et la période de fructification des manguiers en Côte d'Ivoire, les populations de B. invadens présentent différents pics de croissance. Conclusion. Des études complémentaires sur la biologie et le comportement de ce ravageur s'avéreront nécessaires pour l'application des méthodes de lutte optimale en vergers en Afrique de l'Ouest et, plus particulièrement, en Côte d'Ivoire. (Résumé d'auteur

Evaluating Efficiency of Different Sampling Methods for Arboreal Ants (Hymenoptera: Formicidae) in A West African Forest-Savanna Mosaic

Ants constitute an important part of arboreal arthropod biomass in rainforests. Nevertheless, there are only a few methods which permit a rapid assessment of these insects in the canopy layer. This study aims at evaluating the efficiency of a new variant type of pitfall trap i.e. “the funnel trap”, to sample arboreal ants in a secondary and gallery forest in Lamto reserve (Côte d’Ivoire). This method was compared to standard arboreal pitfall trap and beating. In total, the 3 methods yielded 7072 ant workers belonging to 43 species, 14 genera and 5 subfamilies. Tree beating recorded the highest ant’s numerical abundance (3670 workers), with 27 species, 12 genera and 3 subfamilies followed by the “funnel trap” that yielded 2800 ant workers, with 23 species belonging to 12 genera and 5 subfamilies. Finally, arboreal pitfall traps caught the lowest individual with 602 ant workers from 20 species belonging to 9 genera and 3 subfamilies. The composition of species which are caught by arboreal pitfall trap and “funnel trap” was similar at 53 percent. Tree beating showed a distinct species composition compared to arboreal pitfall trap and “funnel trap”. The “funnel trap” could be a fast and efficient way to quickly assess ant-biodiversity in forest canopies and agroecosystems as it looks like a non-destructive sampling method

Economic and environmental strategies for process design

This paper first addresses the definition of various objectives involved in eco-efficient processes, taking simultaneously into account ecological and economic considerations. The environmental aspect at the preliminary design phase of chemical processes is quantified by using a set of metrics or indicators following the guidelines of sustainability concepts proposed by . The resulting multiobjective problem is solved by a genetic algorithm following an improved variant of the so-called NSGA II algorithm. A key point for evaluating environmental burdens is the use of the package ARIANE™, a decision support tool dedicated to the management of plants utilities (steam, electricity, hot water, etc.) and pollutants (CO2, SO2, NO, etc.), implemented here both to compute the primary energy requirements of the process and to quantify its pollutant emissions. The well-known benchmark process for hydrodealkylation (HDA) of toluene to produce benzene, revisited here in a multiobjective optimization way, is used to illustrate the approach for finding eco-friendly and cost-effective designs. Preliminary biobjective studies are carried out for eliminating redundant environmental objectives. The trade-off between economic and environmental objectives is illustrated through Pareto curves. In order to aid decision making among the various alternatives that can be generated after this step, a synthetic evaluation method, based on the so-called Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) (), has been first used. Another simple procedure named FUCA has also been implemented and shown its efficiency vs. TOPSIS. Two scenarios are studied; in the former, the goal is to find the best trade-off between economic and ecological aspects while the latter case aims at defining the best compromise between economic and more strict environmental impact