Efficient Algorithms for Reliability Evaluation of General Networks

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Clustering Prediction Techniques in Defining and Predicting Customers Defection: The Case of E-Commerce Context

With the growth of the e-commerce sector, customers have more choices, a fact which encourages them to divide their purchases amongst several e-commerce sites and compare their competitors’ products, yet this increases high risks of churning. A review of the literature on customer churning models reveals that no prior research had considered both partial and total defection in non-contractual online environments. Instead, they focused either on a total or partial defect. This study proposes a customer churn prediction model in an e-commerce context, wherein a clustering phase is based on the integration of the k-means method and the Length-Recency-Frequency-Monetary (LRFM) model. This phase is employed to define churn followed by a multi-class prediction phase based on three classification techniques: Simple decision tree, Artificial neural networks and Decision tree ensemble, in which the dependent variable classifies a particular customer into a customer continuing loyal buying patterns (Non-churned), a partial defector (Partially-churned), and a total defector (Totally-churned). Macro-averaging measures including average accuracy, macro-average of Precision, Recall, and F-1 are used to evaluate classifiers’ performance on 10-fold cross validation. Using real data from an online store, the results show the efficiency of decision tree ensemble model over the other models in identifying both future partial and total defection

A Systemic Approach to Consider Complexity in Sawmill Modeling

The lumber industry is challenged to operate more efficiently. Sawmill systems use much equipment with various technologies and their management methods are very much influenced by size of operation, employee skills, hierarchy levels, and the high volatility of softwood lumber commodity markets. Because of interactions between the different manufacturing system components, its management becomes a complex matter. It is therefore difficult to assess the effect of given perturbations or improvements on the overall system.This study proposes a modeling approach based on the concept of system that provides a comprehensive view for modeling and analyzing sawmill systems. Adaptations of existing formalisms to represent operating, information, and decision sub-systems are put forward, while assembling these three sub-systems in an overall model gives a new vision of the sawmill and a powerful tool for systems integration. This modeling approach could be used for diagnostic as well as for sawmill improvement. Various examples are provided on the application of this approach

A synthesis and characterization of lanthanum potassium niobate oxide with tetragonal tungsten bronze (TTB) type structure

The main aim of this study is to lower the reaction and sintering temperatures of K2LaNb5O15 in order to improve the quality of this material. The K2LaNb5O15 compound has been synthetized by soft chemistry (coprecipitation) and its physico-chemical properties were studied.This method permits the synthesis of chemical purty, fine powder materials with good crystallization at low temperatures.The main aim of this study is to lower the reaction and sintering temperatures of K2LaNb5O15 in order to improve the quality of this material. The K2LaNb5O15 compound has been synthetized by soft chemistry (coprecipitation) and its physico-chemical properties were studied.This method permits the synthesis of chemical purty, fine powder materials with good crystallization at low temperatures

A hybrid camera- and ultrasound-based approach for needle localization and tracking using a 3D motorized curvilinear ultrasound probe

Three-dimensional (3D) motorized curvilinear ultrasound probes provide an effective, low-cost tool to guide needle interventions, but localizing and tracking the needle in 3D ultrasound volumes is often challenging. In this study, a new method is introduced to localize and track the needle using 3D motorized curvilinear ultrasound probes. In particular, a low-cost camera mounted on the probe is employed to estimate the needle axis. The camera-estimated axis is used to identify a volume of interest (VOI) in the ultrasound volume that enables high needle visibility. This VOI is analyzed using local phase analysis and the random sample consensus algorithm to refine the camera-estimated needle axis. The needle tip is determined by searching the localized needle axis using a probabilistic approach. Dynamic needle tracking in a sequence of 3D ultrasound volumes is enabled by iteratively applying a Kalman filter to estimate the VOI that includes the needle in the successive ultrasound volume and limiting the localization analysis to this VOI. A series of ex vivo animal experiments are conducted to evaluate the accuracy of needle localization and tracking. The results show that the proposed method can localize the needle in individual ultrasound volumes with maximum error rates of 0.7 mm for the needle axis, 1.7° for the needle angle, and 1.2 mm for the needle tip. Moreover, the proposed method can track the needle in a sequence of ultrasound volumes with maximum error rates of 1.0 mm for the needle axis, 2.0° for the needle angle, and 1.7 mm for the needle tip. These results suggest the feasibility of applying the proposed method to localize and track the needle using 3D motorized curvilinear ultrasound probes

Toward a strategic approach to end-of-life aircraft recycling projects : a research agenda in transdisciplinary context

The number of planes at the end of life is increasing. Innovative management practice of aircraft at the end of life can be considered as a transdisciplinary context. Moreover, regarding dynamics and multidimensionality of aircraft recycling projects, conventional management systems cannot be sufficient and responsive. The purpose of this paper is to address a research agenda that support various aspects of dynamics and transdisciplinarity of end of life aircraft recycling projects (EOLARP) by a strategic conceptual framework. Four sections of the framework including business model, market and industry, knowledge management and performance measurement make a basis for addressing the essential issues in EOLARP business ecosystem, which needs an incorporated approach of different disciplines and players. Further studies and works on each arena in this framework are valuable in overcoming difficulties facing managers and strategic partners in EOLARP

Effect of age, clone heads, ramet position and IBA treatment on the rooting of Argan tree (Argania spinosa L. Skeels) cuttings

The vegetative propagation of the Argan tree by cuttings was carried out in a glazed enclosure whose relative humidity and average temperature were 80% and 25 °C respectively. The first trial involved herbaceous cuttings taken from clone heads selected on the basis of productivity, vigor and ability to produce cuttings at different levels (heights) of the tree. Three factors were taken into account: the age of the root-stock, the branch position on the tree and the treatment with indol-butyric acid (IBA), a rooting hormone whose concentrations were 1000 and 2000 ppm compared to a control treated with distilled water. A second trial was conducted to control the overall conditions for cuttings rooting such as light, relative air humidity and substrate temperature, as well as the type of the cuttings: herbaceous, semi-woody and woody. The overall rooting rate was improved by four folds between de first and the second trial. It increased from 25% under uncontrolled conditions to 100% under controlled conditions in some clones. Young trees showed the greatest ability to root. Variance analysis showed a highly significant effect of clone head and branch position on rooting, dry weight and average length of cuttings. On the other hand, no significant effect was observed for auxin treatment on these variables. The best result (100% rooting) was obtained for apical and median cuttings of sprouts of young trees under controlled conditions. Tree age has a highly significant effect on root quality since cuttings from young trees showed superior dry weight and root length. The comparative study of the root system produced by cuttings with that of seedlings showed that seedlings are characterized by a well-developed taproot while cuttings develop a cluster of cells that give rise to several orthotropic roots