Cheickna Sylla - Academia.edu (original) (raw)

Papers by Cheickna Sylla

A significant problem encountered in designing flight simulator device training programs is the o... more A significant problem encountered in designing flight simulator device training programs is the of lack a decision support system (DSS) providing a unified methodology for establishing appropriate training criteria and optimal training device parameters. This paper presents an efficient DSS for cost-effectiveness analysis for the optimal design of the Instructor Operator Station (IOS) in flight simulators. This IOS can be used to teach a multiple of training phases. This DSS integrates three relatively distinct areas: (1) learning curve modeling, (2) economic analysis, and (3) multi-criteria decision making for the design tradeoffs optimization. The paper presents the methods for deriving the IOS design configurations from an initial broadly defined set of training objectives and the related training taxonomy of training devices from the training expert's opinions. The data requirement for making the design tradeoff decisions and the methods and sources of that data are also proposed in this paper. This DSS is designed to assist engineers and training specialists in their decision making for simulators and other training device design and development projects.

Human Factors: The Journal of the Human Factors and Ergonomics Society

ABSTRACT

Technology Management the New International Language, Oct 27, 1991

CAD/CAM Robotics and Factories of the Future, 1989

Control Engineering Practice, 2002

The traditional job of a quality control inspector, whether human or a machine-vision device, is ... more The traditional job of a quality control inspector, whether human or a machine-vision device, is to discriminate products into acceptable and non-acceptable items. The performance of inspectors can be measured in terms of rejecting non-acceptable items (Type I error) or classifying non-acceptable items as acceptable (Type II error). Reinspection is often used afterward to remedy this situation if required. Unfortunately,

Computers in Industry, 1995

ABSTRACT Acceptance sampling by attributes is now a universal and fundamental tool in statistical... more ABSTRACT Acceptance sampling by attributes is now a universal and fundamental tool in statistical quality control. Among the various plans, single sampling has been recognized to offer significant cost savings and administrative simplicity. Single sampling by attributes is generally carried out or supervised by a human inspector. Unfortunately, human inspection error is another fact of life in industrial inspection. Two types of errors are possible. One is the Type 1 error, in which a good item is classified as defective (i.e., nonconforming); the other is the Type 2 error, in which a defective item is passed as good. Presently, little has been written on the effects of inspection errors on the outgoing quality and on how to compensate for these errors. The research objective of this paper is to show how a knowledge of the errors can be used to design compensating acceptance sampling plans for industrial quality control tasks. In contrast to the typical human inspection models in quality control, with fixed performance irrespective of incoming product quality, the model proposed here uses a form of signal detection theory (SDT) to predict inspector performance in order to improve system performance. The paper proposes the concept of lability, measured by a number ranging from 0 to 1, to characterize an inspector's ability to response to costs, rewards and probabilities involved in the inspection decision. This concept allows the modeling of both a constant-error inspector having a lability of 0, an SDT inspector having a lability of 1, and all those which fall within this range. Using this concept, the paper presents two models of the human inspector with considerations of: (a) constant Type 1 and Type 2 errors independent of the incoming fraction nonconforming, and (b) increasing Type 2 error and decreasing Type 1 error with increasing fraction nonconforming as specified by SDT. A general model covering these inspection errors is proposed. The paper shows that an imperfect inspector, who can detect the signal properly to adjust the decision criterion conservatively in the direction specified by the SDT, can compensate for the potential errors. A numerical example is proposed to illustrate the model application.

Computers & Industrial Engineering, 1989

Computers & Industrial Engineering, 1995

Al~traet-A model is presented for planning the operations of interconnected surface water resourc... more Al~traet-A model is presented for planning the operations of interconnected surface water resource facilities equipped with hydroelectric power stations. These facilities are operated for the purpose of water supply, hydroelectric power generation and low flow augmentation for navigation purpose. The model is formulated as a deterministic large-scale nonlinear program, with decision variables being the monthly reservoir releases, and canal and pipeline flows through turbines. A solution procedure is proposed based on penalty method in which the nonlinear constraints are assigned penalty weights and moved to the objective function. The resulting problem with linear constraints is solved using reduced gradient techniques. The calculations of the reduced gradient is carried out efficiently by utilizing the special structure of the matrix involved in the linear equality constraints. The results of this procedure are compared against those obtained using a subgradient optimization algorithm. The method has been validated using a five-reservoir system of the Senegal River Basin in West Africa, where it serves as the model-base of the planning decision support system.

Computers & Industrial Engineering, 1988

The rapid development of Computer Integrated Manufacturing (CIM) is causing significant difficult... more The rapid development of Computer Integrated Manufacturing (CIM) is causing significant difficulties for planning the information requirements for the technical managers of quality assurance systems. This paper examines the general model of information requirements planning for quality assurances with emphasis on the problems of structuring and adapting to a CIM environment.

Computers & Industrial Engineering, 1988

The U.S. Army Research Institute and its Program Manager for Training Devices are developing a la... more The U.S. Army Research Institute and its Program Manager for Training Devices are developing a large scale computerized system to enable trade-off studies leading to the design of cost-effective simulators. An important component of this system is the Optimization of Simulation-Based Training Systems (OSBATS). In its present form the development of OSBATS includes five software subsystems. The most important subsystem , based on operational criticality (simulator training performance), costs and design difficulties, is the Instructor/Operator Station (lOS) subsystem. This paper presents some of the industrial and human factors engineering issues related to the conceptual framework of the design of the lOS. It also presents a large scale mix-integer programming formulation of the design problem, and briefly elaborates on the data collection procedures being developed for the highly subjective training components of the model.

Computers & Industrial Engineering, 1987

An assignment arrangement problem (AAP), in which an arrangement represents a geometric straight ... more An assignment arrangement problem (AAP), in which an arrangement represents a geometric straight line joining two pre-defined points (for facility and location), is introduced. This problem is a special class of QAP, and is different from all existing QAP's, as it requires a pre-established order between all assignments included in addition to a multi-objective function involved. It is shown that this un-conventional problem cannot be solved using current conventional exchange heuristic procedures. A new pairwise exchange is developed and programmed for solution and evaluation. The AAP and the solution procedure introduced are flexible and may be applicable to other problems which fit the general QAP formulation.

l'atteinte neurologique périphérique a toujours été sousestimée dans la prise en charge des fistu... more l'atteinte neurologique périphérique a toujours été sousestimée dans la prise en charge des fistules vésico-vaginales d'origine obstétricale. Nous pensons que la fistule n'est que la manifestation apparente des "dégâts neurovésicaux" qui restent déterminants dans le pronostic. Ils expliquent pour une bonne part la grande fréquence des échecs thérapeutiques.

International Journal of Networking and Virtual Organisations, 2011

Hepatology, 1999

The impact of hepatitis B (HBV) and C (HCV) on patient survival after kidney transplantation is c... more The impact of hepatitis B (HBV) and C (HCV) on patient survival after kidney transplantation is controversial. The aims of this study were (1) to assess the independent prognostic values of HBsAg and anti-HCV in a large renal transplant population, (2) to compare infected patients with noninfected patients matched for factors possibly associated with graft and patient survival, and (3) to assess the prognostic value of biopsy-proven cirrhosis. Eight hundred thirty-four transplanted patients were included: 128 with positive HBsAg (group I), 216 with positive anti-HCV (group II), and 490 without serological markers of HBV and HCV (group III). Fifteen percent and 29% of patients were HBsAg-positive and anti-HCV-positive, respectively. Tenyear survivals of group I (55 ؎ 6%) and group II (65 ؎ 5%) were significantly lower than survival of group III (80 ؎ 3%, P F .001). At 10 years, among overall patients with HCV screening (n ‫؍‬ 834), four variables had independent prognostic values in patient survival: age at transplantation (P F .0001), year of transplantation (P ‫؍‬ .02), biopsyproven cirrhosis (P ‫؍‬ .03), and presence of HCV antibodies (P ‫؍‬ .02). In the case control study, comparison of infected patients with their matched control patients showed that age at transplantation (P F .05), HBsAg (P ‫؍‬ .005), and anti-HCV (P ‫؍‬ .005) were independent prognostic factors. HCV, biopsy-proven cirrhosis, and age are independent prognostic factors of 10-year survival in patients with kidney grafts. The case-control study showed that anti-HCV and HBsAg were independently associated with patient and graft survivals. In infected patients, a routine liver histological analysis would improve selection of patients for renal transplantation.(HEPATOLOGY 1999;29:257-263.)

Control Engineering Practice, 1993

A significant problem encountered in designing flight simulator device training programs is the o... more A significant problem encountered in designing flight simulator device training programs is the of lack a decision support system (DSS) providing a unified methodology for establishing appropriate training criteria and optimal training device parameters. This paper presents an efficient DSS for cost-effectiveness analysis for the optimal design of the Instructor Operator Station (IOS) in flight simulators. This IOS can be used to teach a multiple of training phases. This DSS integrates three relatively distinct areas: (1) learning curve modeling, (2) economic analysis, and (3) multi-criteria decision making for the design tradeoffs optimization. The paper presents the methods for deriving the IOS design configurations from an initial broadly defined set of training objectives and the related training taxonomy of training devices from the training expert's opinions. The data requirement for making the design tradeoff decisions and the methods and sources of that data are also proposed in this paper. This DSS is designed to assist engineers and training specialists in their decision making for simulators and other training device design and development projects.

Human Factors: The Journal of the Human Factors and Ergonomics Society

ABSTRACT

Technology Management the New International Language, Oct 27, 1991

CAD/CAM Robotics and Factories of the Future, 1989

Control Engineering Practice, 2002

The traditional job of a quality control inspector, whether human or a machine-vision device, is ... more The traditional job of a quality control inspector, whether human or a machine-vision device, is to discriminate products into acceptable and non-acceptable items. The performance of inspectors can be measured in terms of rejecting non-acceptable items (Type I error) or classifying non-acceptable items as acceptable (Type II error). Reinspection is often used afterward to remedy this situation if required. Unfortunately,

Computers in Industry, 1995

ABSTRACT Acceptance sampling by attributes is now a universal and fundamental tool in statistical... more ABSTRACT Acceptance sampling by attributes is now a universal and fundamental tool in statistical quality control. Among the various plans, single sampling has been recognized to offer significant cost savings and administrative simplicity. Single sampling by attributes is generally carried out or supervised by a human inspector. Unfortunately, human inspection error is another fact of life in industrial inspection. Two types of errors are possible. One is the Type 1 error, in which a good item is classified as defective (i.e., nonconforming); the other is the Type 2 error, in which a defective item is passed as good. Presently, little has been written on the effects of inspection errors on the outgoing quality and on how to compensate for these errors. The research objective of this paper is to show how a knowledge of the errors can be used to design compensating acceptance sampling plans for industrial quality control tasks. In contrast to the typical human inspection models in quality control, with fixed performance irrespective of incoming product quality, the model proposed here uses a form of signal detection theory (SDT) to predict inspector performance in order to improve system performance. The paper proposes the concept of lability, measured by a number ranging from 0 to 1, to characterize an inspector's ability to response to costs, rewards and probabilities involved in the inspection decision. This concept allows the modeling of both a constant-error inspector having a lability of 0, an SDT inspector having a lability of 1, and all those which fall within this range. Using this concept, the paper presents two models of the human inspector with considerations of: (a) constant Type 1 and Type 2 errors independent of the incoming fraction nonconforming, and (b) increasing Type 2 error and decreasing Type 1 error with increasing fraction nonconforming as specified by SDT. A general model covering these inspection errors is proposed. The paper shows that an imperfect inspector, who can detect the signal properly to adjust the decision criterion conservatively in the direction specified by the SDT, can compensate for the potential errors. A numerical example is proposed to illustrate the model application.

Computers & Industrial Engineering, 1989

Computers & Industrial Engineering, 1995

Al~traet-A model is presented for planning the operations of interconnected surface water resourc... more Al~traet-A model is presented for planning the operations of interconnected surface water resource facilities equipped with hydroelectric power stations. These facilities are operated for the purpose of water supply, hydroelectric power generation and low flow augmentation for navigation purpose. The model is formulated as a deterministic large-scale nonlinear program, with decision variables being the monthly reservoir releases, and canal and pipeline flows through turbines. A solution procedure is proposed based on penalty method in which the nonlinear constraints are assigned penalty weights and moved to the objective function. The resulting problem with linear constraints is solved using reduced gradient techniques. The calculations of the reduced gradient is carried out efficiently by utilizing the special structure of the matrix involved in the linear equality constraints. The results of this procedure are compared against those obtained using a subgradient optimization algorithm. The method has been validated using a five-reservoir system of the Senegal River Basin in West Africa, where it serves as the model-base of the planning decision support system.

Computers & Industrial Engineering, 1988

The rapid development of Computer Integrated Manufacturing (CIM) is causing significant difficult... more The rapid development of Computer Integrated Manufacturing (CIM) is causing significant difficulties for planning the information requirements for the technical managers of quality assurance systems. This paper examines the general model of information requirements planning for quality assurances with emphasis on the problems of structuring and adapting to a CIM environment.

Computers & Industrial Engineering, 1988

The U.S. Army Research Institute and its Program Manager for Training Devices are developing a la... more The U.S. Army Research Institute and its Program Manager for Training Devices are developing a large scale computerized system to enable trade-off studies leading to the design of cost-effective simulators. An important component of this system is the Optimization of Simulation-Based Training Systems (OSBATS). In its present form the development of OSBATS includes five software subsystems. The most important subsystem , based on operational criticality (simulator training performance), costs and design difficulties, is the Instructor/Operator Station (lOS) subsystem. This paper presents some of the industrial and human factors engineering issues related to the conceptual framework of the design of the lOS. It also presents a large scale mix-integer programming formulation of the design problem, and briefly elaborates on the data collection procedures being developed for the highly subjective training components of the model.

Computers & Industrial Engineering, 1987

An assignment arrangement problem (AAP), in which an arrangement represents a geometric straight ... more An assignment arrangement problem (AAP), in which an arrangement represents a geometric straight line joining two pre-defined points (for facility and location), is introduced. This problem is a special class of QAP, and is different from all existing QAP's, as it requires a pre-established order between all assignments included in addition to a multi-objective function involved. It is shown that this un-conventional problem cannot be solved using current conventional exchange heuristic procedures. A new pairwise exchange is developed and programmed for solution and evaluation. The AAP and the solution procedure introduced are flexible and may be applicable to other problems which fit the general QAP formulation.

l'atteinte neurologique périphérique a toujours été sousestimée dans la prise en charge des fistu... more l'atteinte neurologique périphérique a toujours été sousestimée dans la prise en charge des fistules vésico-vaginales d'origine obstétricale. Nous pensons que la fistule n'est que la manifestation apparente des "dégâts neurovésicaux" qui restent déterminants dans le pronostic. Ils expliquent pour une bonne part la grande fréquence des échecs thérapeutiques.

International Journal of Networking and Virtual Organisations, 2011

Hepatology, 1999

The impact of hepatitis B (HBV) and C (HCV) on patient survival after kidney transplantation is c... more The impact of hepatitis B (HBV) and C (HCV) on patient survival after kidney transplantation is controversial. The aims of this study were (1) to assess the independent prognostic values of HBsAg and anti-HCV in a large renal transplant population, (2) to compare infected patients with noninfected patients matched for factors possibly associated with graft and patient survival, and (3) to assess the prognostic value of biopsy-proven cirrhosis. Eight hundred thirty-four transplanted patients were included: 128 with positive HBsAg (group I), 216 with positive anti-HCV (group II), and 490 without serological markers of HBV and HCV (group III). Fifteen percent and 29% of patients were HBsAg-positive and anti-HCV-positive, respectively. Tenyear survivals of group I (55 ؎ 6%) and group II (65 ؎ 5%) were significantly lower than survival of group III (80 ؎ 3%, P F .001). At 10 years, among overall patients with HCV screening (n ‫؍‬ 834), four variables had independent prognostic values in patient survival: age at transplantation (P F .0001), year of transplantation (P ‫؍‬ .02), biopsyproven cirrhosis (P ‫؍‬ .03), and presence of HCV antibodies (P ‫؍‬ .02). In the case control study, comparison of infected patients with their matched control patients showed that age at transplantation (P F .05), HBsAg (P ‫؍‬ .005), and anti-HCV (P ‫؍‬ .005) were independent prognostic factors. HCV, biopsy-proven cirrhosis, and age are independent prognostic factors of 10-year survival in patients with kidney grafts. The case-control study showed that anti-HCV and HBsAg were independently associated with patient and graft survivals. In infected patients, a routine liver histological analysis would improve selection of patients for renal transplantation.(HEPATOLOGY 1999;29:257-263.)

Control Engineering Practice, 1993