General Dynamics

About: General Dynamics is a company organization based out in Fairfax, Virginia, United States. It is known for research contribution in the topics: Signal & Propellant. The organization has 5722 authors who have published 5819 publications receiving 85768 citations. The organization is also known as: GD & General Dynamics Corporation.

Generalized method of predicting optimal performance of active noise controllers

Abstract: In this investigation, the formulation for studying the performance of an optimal active noise controller for harmonic, enclosed sound fields is derived using an indirect boundary-element method. The optimal active noise controller is defined as the volume velocity secondary source strengths that minimize the sound pressure level at a number of discrete interior locations. In addition, the formulation for studying the performance of an optimal active noise controller that minimizes the free-field power radiated from a generalized, distributed noise source is presented. Representative results are provided for each formulation. For the enclosure problem, results are given for global control and local control schemes using a rectangular enclosure. For the free-field radiation problem, the effects of secondary source location and quantity on active noise controller performance are investigated. The relative merits of each formulation are discussed.

Determination of Cytochrome P450 Isoenzyme 2D6 (CYP2D6) Genotypes and Pharmacogenomic Impact on Primaquine Metabolism in an Active-Duty US Military Population.

Abstract: Background Plasmodium vivax malaria requires a 2-week course of primaquine (PQ) for radical cure. Evidence suggests that the hepatic isoenzyme cytochrome P450 2D6 (CYP2D6) is the key enzyme required to convert PQ into its active metabolite. Methods CYP2D6 genotypes and phenotypes of 550 service personnel were determined, and the pharmacokinetics (PK) of a 30-mg oral dose of PQ was measured in 45 volunteers. Blood and urine samples were collected, with PQ and metabolites were measured using ultraperformance liquid chromatography with mass spectrometry. Results Seventy-six CYP2D6 genotypes were characterized for 530 service personnel. Of the 515 personnel for whom a single phenotype was predicted, 58% had a normal metabolizer (NM) phenotype, 35% had an intermediate metabolizer (IM) phenotype, 5% had a poor metabolizer (PM) phenotype, and 2% had an ultrametabolizer phenotype. The median PQ area under the concentration time curve from 0 to ∞ was lower for the NM phenotype as compared to the IM or PM phenotypes. The novel 5,6-ortho-quinone was detected in urine but not plasma from all personnel with the NM phenotype. Conclusion The plasma PK profile suggests PQ metabolism is decreased in personnel with the IM or PM phenotypes as compared to those with the NM phenotype. The finding of 5,6-ortho-quinone, the stable surrogate for the unstable 5-hydroxyprimaquine metabolite, almost exclusively in personnel with the NM phenotype, compared with sporadic or no production in those with the IM or PM phenotypes, provides further evidence for the role of CYP2D6 in radical cure. Clinical trials registration NCT02960568.

Modelling and optimal control of a production process

Abstract: An industrial production process is modelled as a discrete-time system with a disturbance input due to sales. The state consists of rates of flow of parts or subassemblies at various work stations, backlogs of parts awaiting processing, and the inventory level of the finished product. The control variables are the man-hours scheduled for various work processes. A quadratic performance criterion is minimized so as to keep state and control variables near desired values. Dynamic programming is used and numerical examples are provided.