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  • 1
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    High Stability Engine Control (HISTEC): Flight Demonstration Results (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Future aircraft turbine engines, both commercial and military, must be able to accommodate expected increased levels of steady-state and dynamic engine-face distortion. The current approach of incorporating sufficient design stall margin to tolerate these increased levels of distortion would significantly reduce performance. The High Stability Engine Control (HISTEC) program has developed technologies for an advanced, integrated engine control system that uses measurement- based estimates of distortion to enhance engine stability. The resulting distortion tolerant control reduces the required design stall margin, with a corresponding increase in performance and/or decrease in fuel burn. The HISTEC concept was successfully flight demonstrated on the F-15 ACTIVE aircraft during the summer of 1997. The flight demonstration was planned and carried out in two parts, the first to show distortion estimation, and the second to show distortion accommodation. Post-flight analysis shows that the HISTEC technologies are able to successfully estimate and accommodate distortion, transiently setting the stall margin requirement on-line and in real-time. Flight demonstration of the HISTEC technologies has significantly reduced the risk of transitioning the technology to tactical and commercial engines.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-1998-208655 , NAS 1.15:208655 , SAE-985556 , E-11375 , 1998 World Aviation Congress and Exposition; Sep 28, 1998 - Sep 30, 1998; Anaheim, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Development and Testing of a High Stability Engine Control (HISTEC) System (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Flight tests were recently completed to demonstrate an inlet-distortion-tolerant engine control system. These flight tests were part of NASA's High Stability Engine Control (HISTEC) program. The objective of the HISTEC program was to design, develop, and flight demonstrate an advanced integrated engine control system that uses measurement-based, real-time estimates of inlet airflow distortion to enhance engine stability. With improved stability and tolerance of inlet airflow distortion, future engine designs may benefit from a reduction in design stall-margin requirements and enhanced reliability, with a corresponding increase in performance and decrease in fuel consumption. This paper describes the HISTEC methodology, presents an aircraft test bed description (including HISTEC-specific modifications) and verification and validation ground tests. Additionally, flight test safety considerations, test plan and technique design and approach, and flight operations are addressed. Some illustrative results are presented to demonstrate the type of analysis and results produced from the flight test program.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-1998-206562 , H-2269 , NAS 1.15:206562 , AIAA Paper 98-3715 , Propulsion; Jul 13, 1998 - Jul 15, 1998; Cleveland, OH; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    High Stability Engine Control (HISTEC) Flight Test Results (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The High Stability Engine Control (HISTEC) Program, managed and funded by the NASA Lewis Research Center, is a cooperative effort between NASA and Pratt & Whitney (P&W). The program objective is to develop and flight demonstrate an advanced high stability integrated engine control system that uses real-time, measurement-based estimation of inlet pressure distortion to enhance engine stability. Flight testing was performed using the NASA Advanced Controls Technologies for Integrated Vehicles (ACTIVE) F-15 aircraft at the NASA Dryden Flight Research Center. The flight test configuration, details of the research objectives, and the flight test matrix to achieve those objectives are presented. Flight test results are discussed that show the design approach can accurately estimate distortion and perform real-time control actions for engine accommodation.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-1998-208481 , E-11255 , NAS 1.15:208481 , AIAA Paper 98-3757 , Propulsion; Jul 12, 1998 - Jul 15, 1998; Cleveland, OH; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    The High Stability Engine Control (HISTEC) Program: Flight Demonstration Phase (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Future aircraft turbine engines, both commercial and military, must be able to accommodate expected increased levels of steady-state and dynamic engine-face distortion. The current approach of incorporating sufficient design stall margin to tolerate these increased levels of distortion would significantly reduce performance. The objective of the High Stability Engine Control (HISTEC) program is to design, develop, and flight-demonstrate an advanced, integrated engine control system that uses measurement-based estimates of distortion to enhance engine stability. The resulting distortion tolerant control reduces the required design stall margin, with a corresponding increase in performance and decrease in fuel burn. The HISTEC concept has been developed and was successfully flight demonstrated on the F-15 ACTIVE aircraft during the summer of 1997. The flight demonstration was planned and carried out in two phases, the first to show distortion estimation, and the second to show distortion accommodation. Post-flight analysis shows that the HISTEC technologies are able to successfully estimate and accommodate distortion, transiently setting the stall margin requirement on-line and in real-time. This allows the design stall margin requirement to be reduced, which in turn can be traded for significantly increased performance and/or decreased weight. Flight demonstration of the HISTEC technologies has significantly reduced the risk of transitioning the technology to tactical and commercial engines.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-1998-208482 , E-11257 , NAS 1.15:208482 , AIAA Paper 98-3756 , Joint Propulsion Conference; Jul 12, 1998 - Jul 15, 1998; Cleveland, OH; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
    Electronic Resource
    Electronic Resource
    Role of capillary electrophoresis methods in the drug development process (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 108-121 
    Details
    ISSN: 0899-0042
    Keywords: chiral purity ; pharmaceutical ; achiral ; cyclodextrin ; SBE cyclodextrin ; purity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the past several years, capillary electrophoresis (CE) has generated considerable interest from pharmaceutical companies for control of both the chiral and achiral purity of bulk drugs and drug products. This paper evaluates the use of CE as: (1) a technique complementary to HPLC for the determination of peak homogeneity of a drug, (2) for determination of chiral purity, and (3) for determination of achiral purity. It would be greatly advantageous if CE could be used to determine both the chiral and achiral purity in a single assay. This investigation compares the results obtained for the separation of the enantiomers of duloxetine using several neutral cyclodextrins to those obtained using anionic cyclodextrins (sulfobutyl ether derivatives) as chiral selectors added to the separation buffer. In addition, it reports chiral separations obtained by using neutral cyclodextrins in a sulfonic acid-coated capillary column, which give a negatively charged capillary surface and electro-osmotic flow even in low pH buffers. The possible mechanism of separation is discussed. © 1996 Wiley-Liss, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Development of chiral drugs in Japan: An update on regulatory and industrial opinion (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 7 (1995), S. 349-352 
    Details
    ISSN: 0899-0042
    Keywords: development of chiral drugs ; regulatory affairs ; industrial opinion ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The purpose of this commentary is to provide information on the present status of the racemate/enantiomer debate in Japan and current industrial and regulatory attitudes to chiral drugs in Japan. It provides an update of our previous paper (Shindo and Caldwell, Chirality 3:91-93, 1991), and the interested reader is referred to this for background information. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530070507
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    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Separation of R- and S-Thalidomide by Reversed-Phase HPLC with β-cyclodextrin in the mobile phase (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 11-17 
    Details
    ISSN: 0899-0042
    Keywords: thalidomide enantiomers ; mobile phase additive ; stereoselective analysis ; high-performance liquid chromatography ; chiral separation ; β-cyclodextrin ; inclusion complex ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: R- and S-Thalidomide were resolved by reversed-phase HPLC on a C-18 column with β-cyclodextrin in the mobile phase. As the concentration of β-cyclodextrin was increased stepwise from 0 to 20 mM, enantiomeric resolution increased and retention times decreased significantly. The influence of different organic modifiers in the mobile phase were evaluated, and ethanol, among others, proved to be effective. Equilibrium constants for the formation of β-cyclodextrin inclusion complexes of R- and S-thalidomide in EtOH-buffer (5:95) were calculated to be 64 and 76 M-1, respectively. © 1996 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Method development in liquid chromatography with a charged cyclodextrin additive for chiral resolution of rac-amlodipine utilising a central composite design (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 466-476 
    Details
    ISSN: 0899-0042
    Keywords: rac-amlodipine ; amlodipine ; liquid chromatography ; chiral ; charged cyclodextrin ; optimisation ; central composite design ; mobile phase additive ; experimental design ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A negatively charged derivative of β-cyclodextrin, sulphobutyl ether-β-cyclodextrin (SBE-β-CD), was examined as a chiral mobile phase additive in reversed-phase high-performance liquid chromatography for the enantiomeric resolution of the calcium channel blocker rac-amlodipine. Theoretical and practical aspects are discussed for setting up a central composite design applicable to any analytical method. These include the correct location of factor points for maintaining orthogonality within the design and the augmentation of centrepoint experiments to allow a larger factor space by increasing the distance of axial star points. Optimised separation was achieved using a reverse-phase column with eluent comprising: acetonitrile (ACN) - potassium dihydrogen phosphate (pH 3.93) containing 2.66 mM SBE-bgr;-CD (26.5:73.5% v/v) at a flow rate of 1.0 ml/min. This yielded a Kaiser peak separation index, Pi = 0.96, at tR2 = 52 min with satisfactory reproducibility, relative standard deviation values: tR1, 0.39%; tR2, 0.47% (n = 5). These experimental results were in excellent agreement with those predicted by the SAS software package for a chromatographic response function model. Multiple regression analysis in four dimensions, with three response models based on Rs, Pi, and a function of Pi, produced response surfaces which revealed zones of optimum robustness and illustrated the interactions involved between the key chromatographic factors. Putative proposals for a mechanism involving the interaction of each of the positively charged enantiomers with the negatively charged cyclodextrin are also discussed. These examine the possibility of ion-pairing and inclusion phenomena to account for the excellent resolution observed. © 1996 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chiral recognition in liquid chromatography utilising chargeable cyclodextrins for resolution of doxazosin enantiomers (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 184-190 
    Details
    ISSN: 0899-0042
    Keywords: rac-doxazosin ; doxazosin ; liquid chromatography ; chiral ; carboxymethyl-β-cyclodextrin ; optimisation ; central composite design ; mobile phase additive ; experimental design ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chromatographic resolution of rac-doxazosin using reversed-phase high performance liquid chromatography (HPLC) with the chargeable chiral mobile phase additive, carboxymethyl-β-cyclodextrin (CM-β-CD), is described. The effects of different modifiers (acetonitrile, methanol and tetrahydrofuran), pH, temperature, and cyclodextrin concentration were investigated to (a) assess the key chromatographic parameters for subsequent chemometric optimisation, and (b) explore the enantioselective mechanism. Assuming a 1:1 complex between each doxazosin enantiomer and CM-β-CD, studies of the relationship between the capacity factors (k′) and functions of CM-β-CD concentration indicate that the mechanisms for retention and chiral selectivity are comparable with those proposed earlier by Sybilska et al.1 Stability constants (KG) calculated for rac-doxazosin complexed with CM-β-CD (647 ± 55 and 594 ± 45 M-1 for each enantiomer respectively) are significantly larger than those calculated for the barbiturates complexed with β-CD (ca. 101-108 M-1).1 Investigations on pH indicate an ionic or ion-pair interaction between the anionic CM-β-CD and the cationic doxazosin enantiomers.A central composite design was used to optimise the key chromatographic parameters: pH, methanol (v/v) and CM/β-CD concentration. The Kaiser peak separation index, Pi, was used for the response function. The predicted response for this chiral separation has been compared with that observed experimentally and samples of the four-dimensional response surface have been assessed for their value in showing robustness. Chirality 9:184-190, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Enantioselective separation of enantiomeric amides on three amylose-based chiral stationary phases: Effects of backbone and carbamate side chain chiralities (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 173-177 
    Details
    ISSN: 0899-0042
    Keywords: chiral high-performance liquid chromatography ; polysaccharides ; structure-retention relationships ; amides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of enantiomeric amides have been chromatographed on three amylose-based chiral stationary phases (CSPs): amylose tris(3,5-dimethylphenylcarbamate) (AD-CSP), amylose tris (S-phenylethylcarbamate) (AS-CSP), and amylose tris(R-phenylethyl-carbamate) (AR-CSP). The relative retentions and enantioselectives of the solutes on the three CSPs were compared and basic structure-retention relationships developed to describe the chromatographic results. The data indicate that for these solutes the observed elution order was a function of the chirality of the amylose backbone, while the magnitude of the enantioselective separations was affected by the chirality of the carbamate side chain. Chirality 9:173-177, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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