NASA Scientific and Technical Aerospace Reports

tension. The binder material with microparticles was made by adding 10% by weight aluminum particles into the pure binder
material. The technique SIEM was used to map the strain distributions of the specimen under various magnifications, 40x,
200x, 800x, and 1500x. The relationships between the coefficient of variation of epsilon(sub yy), epsilon(sub xx) and the
examined area were obtained. We found at magnification about 200x the microstructure had a significant effect on the strain
distributions in the binder material with microparticles whereas, for pure binder material, the effect was not observed until at
1500x.
DTIC
Micromechanics; Microparticles
20040073685 University of Southern California, Los Angeles, CA
Analytical and Experimental Studies of Nonlinear System Modeling and Simulation
Masri, Sami F.; Mar. 10, 2004; 13 pp.; In English
Contract(s)/Grant(s): F49620-01-1-0125
Report No.(s): AD-A422584; AFRL-SR-AR-TR-04-0222; No Copyright; Avail: CASI; A03, Hardcopy
The research objectives of this project were to study and resolve some of the daunting problems that hinder the
development of reliable general-purpose computer simulation programs, which are capable of reflecting precisely the dynamic
behavior of distributed nonlinear systems, spanning the range from large joint-dominated space structures, to intricate
electro-mechanical systems, to MEMS, as well as civil infrastructure systems, by conducting a comprehensive analytical and
experimental study to investigate an important subset of the challenging issues.
DTIC
Nonlinear Systems; Simulation
20040073711 Public Health Service, Washington, DC
On the Use of Electrically Stimulated Muscle as a Controlled Actuator of a Limb
Crochetiere, William J.; Jun. 1967; 232 pp.; In English
Contract(s)/Grant(s): RD-1814-M
Report No.(s): AD-A422620; EDC-4-67-17; No Copyright; Avail: CASI; A11, Hardcopy
The feasibility of inducing controlled movement of a paralyzed limb by means of applying electric currents is discussed.
This is preceded by a functional description of muscle and its electrical excitability and the musculo- skeletal system of the
human arm. Experiments are described which were performed to gain a basic understanding of the mechanical response of
the lower arm due to stimulation of the biceps muscle. The dynamic model of this single degree of freedom system thus
obtained is then used to synthesize suitable feedback control schemes. Two basically different systems are discussed: the
control of the angular position, and the control of the angular velocity of the elbow joint. The velocity controller is found to
be superior-and is implemented in hardware. Three types of velocity controllers are compared: open loop, proportional closed
loop, and proportional plus integral closed-loop. The proportional plus integral closed loop is found to be superior. The author
also indicates that a closed loop torque control may perform as well or better and also is simpler to implement.
DTIC
Actuators; Electric Current; Muscles
20040073712 Northwestern Univ., Evanston, IL
Adaptive Signal Processing Techniques for Robust, High Capacity Spread-Spectrum Multiple Access
Honig, Michael L.; Sep. 2, 2003; 7 pp.; In English
Contract(s)/Grant(s): DAAD19-99-1-0288
Report No.(s): AD-A422622; ARO-39184.32-CI; No Copyright; Avail: CASI; A02, Hardcopy
This project is concerned with signal processing and coding techniques, which can improve the performance of
spread-spectrum multiple-access systems. Specific topics investigated during the course of this project include: (1)
Reduced-rank interference suppression; (2) Combined coding and interference suppression, (3) Joint transmitter-receiver
optimization in the presence of multiple access interference; and (4) The effect of limited feedback on the performance of joint
transmitter-receiver optimization schemes. The theory of large random matrices has been used to analyze the performance of
both interference suppression and interference avoidance schemes. For example, we have used these techniques to analyze the
performance of adaptive reduced- and full-rank least squares filtering for interference suppression with limited training. This
analysis shows the effects of algorithm parameters, which determine the initialization and data windowing, along with system
load and noise level. Other contributions include optimization of the ratio of pilot-to- data power and code rate with adaptive
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