23 research outputs found
Modelling of servo-controlled pneumatic drives: a generalised approach to pneumatic modelling and applications in servo-drive design
The primary objective of this research is to develop a
general modelling facility for modular pneumatic servo-drives.
The component-oriented approach has been adopted as the modelling
technique to provide the flexibility of modelling a wide variety
of components and the segmentation of the non-linear system to
less complex uncoupled component modules.
A significant part of the research work has been devoted to
identify a series of component modules of the single axis linear
pneumatic servomechanism with standardised linking variables. The
mathematical models have been implemented in a simulation software
which produces time domain responses for design evaluation
purposes. Alternative components for different servomechanism
design were modelled as mutually exclusive modules which could be
selected for assembly as if they were real physical entities. The
philosophy of the approach was validated by tests on prototype
servo-drives with matching components. Design analysis could be
performed by simulating and comparing the performance of
alternative system structures. [Continues.
Research and Technology Objectives and Plans Summary (RTOPS)
A compilation of the summary portion of each of the Research and Technology Operating Plans (RTOP) used for management review and control of research currently in progress throughout NASA is presented along with citations and abstracts of the RTOPs. Four indexes are included: (1) subject; (2) technical monitor; (3) responsible NASA organization; and (4) RTOP number
Nanomaterial-Based Electrochemical and Colorimetric Sensors for On-Site Detection of Small-Molecule Targets
An ideal biosensor is a compact and in-expensive device that is able to readily and rapidly detects different types of analytes with high sensitivity and specificity. The affectability of a biosensing methodology is subject to the limit of nanomaterials to transduce the target binding process to an improved perceptible signal, while the selectivity is accomplished by considering the binding and specificity of certain moieties to their targets. Keeping these requirements in mind we have chosen nanomaterials such as carbon nanotubes (CNTs) and gold nanoparticles (AuNPs) that has catalytic properties combined with their size, shape and configuration dependent chemical and physical properties as essential precursors and signaling components for creation of biosensors with tremendous sensitivity. The primary goal of the research work described in this dissertation is to develop and evaluate novel methods to detect various analytes using nanomaterials, at the same time making an affordable architecture for point-of-care (POC) applications. We report here in chapter 3 a simple and new strategy for preparing disposable, paper-based, porous AuNP/M-SWCNT hybrid thin gold films with high conductivity, rapid electron transfer rates, and excellent electrocatalytic properties to achieve multiple analyte electrochemical detection with a resolution that greatly exceeds that of purchased flat gold slides. We further explored the use of nanomaterial-based paper films in more complex matrices to detect analytes such as NADH, which can act as a biomarker for certain cellular redox imbalances and disease conditions. Carbon nanotubes with their large activated surfaces and edge-plane sites (defects) that are ideal for performing NADH oxidation at low potentials without any help of redox mediators minimizing surface fouling in complex matrices is described in chapter 4. With an instrument-free approach in mind we further focused on a colorimetric platform using split cocaine aptamers and gold nanoparticles (AuNPs) to detect cocaine for on-site applications as described in chapter 5. In chapter 5, the split aptamer sequences were evaluated mainly on three basic criteria, the hybridization efficiency, specificity towards the analyte (cocaine), and the reaction time to observe a distinguishable color change from red to blue. The assay is an enzyme-assisted target recycling (EATR) strategy following the principle that nuclease enzyme recognizes probe–target complexes, cleaving only the probe strand releasing the target for recycling. We have also studied the effect of the number of binding domains with variable chain lengths on either side of the apurinic (AP) site. On the basis of our results, we finally shortlisted the sequence combination with maximum signal enhancement fold which is instrumental in development of colorimetric platform with faster, and specific reaction to observe a distinctive color change in the presence of cocaine
Aerial Vehicles
This book contains 35 chapters written by experts in developing techniques for making aerial vehicles more intelligent, more reliable, more flexible in use, and safer in operation.It will also serve as an inspiration for further improvement of the design and application of aeral vehicles. The advanced techniques and research described here may also be applicable to other high-tech areas such as robotics, avionics, vetronics, and space
Analysis and control of FES-assisted paraplegic walking with wheel walker.
The number of people with spinal cord injury (SCI) is increasing every year and
walking has been found to be the most exciting and important prospect to these
patients to improve their quality of life. Many individuals with incomplete SCI
have the potential to walk and everyone of them wants to try. Unfortunately up to
now, there is less than one third of patients could walk again after SCI. Residual
function, the orthotic support, energy expenditure, patient motivation and control
technique are some of the factors that influence the walking outcome of spinal cord
injured people. In this thesis, a series of studies are carried out to investigate the
possibility of enhancing the performance of the functional electrical stimulation
(PES) assisted paraplegic walking with wheel walker through the development and
implementation of intelligent control technique and spring brake orthosis (SBO)
with full utilization of the voluntary upper body effort. The main aim of this thesis
is to enable individuals with complete paraplegia to walk again with maximum
performance and the simplest approach as possible.
Firstly, before simulation of the system can be made, it is important to select the
right model to represent the actual plant. In this thesis, the development of a
humanoid and wheel walker models are carried out using MSC.visualNastran4D
(vN4D) software and this is integrated with Matlab Simulink® for simulation. The
newly developed quadriceps and hamstrings muscle models from the series of
experiments are used to represent subject muscles after comparison and validation
with other two well-known muscle models are performed.
Several experiments are conducted to investigate the effect of stimulation frequency
and pulse-width in intermittent stimulation with isometric measurement from
paraplegic subjects. The results from this work can serve as a guidance to determine
the optimum stimulation parameters such as frequency and pulse-width to reduce
muscle fatigue during PES application. The ability test is introduced to determine
the maximum leg force that can be applied to the specific paraplegic subject during
FES functional task with minimum chance of spasm and leg injury.
Investigations are carried out on the control techniques implemented for FES
walking with wheel walker. PID control and fuzzy logic control (FLC) are used to
regulate the electrical stimulation required by the quadriceps and hamstrings
muscles in order to perform the FES walking manoeuvre according to predefined
walking trajectory. The body weight transfer is introduced to increase the efficiency
of FES walking performance. The effectiveness of body weight transfer and control
strategy to enhance the performance of FES walking and reduce stimulation pulses
required is examined.
Investigations are carried out on the effectiveness of spring brake orthosis (SBO)
for FES assisted paraplegic walking with wheel walker. A new concept in hybrid
orthotics provides solutions to the problems that affect current 'hybrid orthosis,
including knee and hip flexion without relying on the withdrawal reflex or a
powered actuator and foot-ground clearance without extra upper body effort. The
use of SBO can also eliminate electrical stimulation pulses required by the
hamstrings muscle for the same FES walking system.
Further improvement of the FES walking system is achieved by introducing finite
state control (FSC) to control the switching time between springs, brakes and
electrical stimulation during FES assisted walking with wheel walker with the
combInation of FLC to regulate the electrical stimulation required for the knee
extension. The results show that FSC can be used to accurately control the
switching time and improve the system robustness and stability
An advanced study of an Application Technology Satellite /ATS-4/ mission, volume I, book 2 Final study report, May - Nov. 1966
Application Technology Satellite /ATS/ SPACECRAFT tradeoff and analysis - configuration paraboloid antenna, guidance and control power, spacecraft design, and apogee motor selectio
18th IEEE Workshop on Nonlinear Dynamics of Electronic Systems: Proceedings
Proceedings of the 18th IEEE Workshop on Nonlinear Dynamics of Electronic Systems, which took place in Dresden, Germany, 26 – 28 May 2010.:Welcome Address ........................ Page I
Table of Contents ........................ Page III
Symposium Committees .............. Page IV
Special Thanks ............................. Page V
Conference program (incl. page numbers of papers)
................... Page VI
Conference papers
Invited talks ................................ Page 1
Regular Papers ........................... Page 14
Wednesday, May 26th, 2010 ......... Page 15
Thursday, May 27th, 2010 .......... Page 110
Friday, May 28th, 2010 ............... Page 210
Author index ............................... Page XII
NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 13)
This issue of the Index Section contains entries for 3386 patent and application for patent citations covering the period May 1969 through June 1978. The Index Section contains five indexes --- subject, inventor, source, number, and accession number
NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 08)
This bibliography is issued in two sections: Section 1 - Abstracts, and Section 2 - Indexes. This issue of the Abstract Section cites 180 patents and applications for patents introduced into the NASA scientific and technical information system during the period July 1975 through December 1975. Each entry in the Abstract Section consists of a citation, an abstract, and, in most cases, a key illustration selected from the patent or application for patent. This issue of the Index Section contains entries for 2,905 patents and applications for patent citations covering the period May 1969 through December 1975. The Index Section contains five indexes -- subject, inventor, source, number, and accession number
NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 10)
Abstracts for 3089 patents and applications for patent entered in the NASA scientific and information system for the period covering May 1969 through December 1976 are indexed by subject, inventor, source, NASA case or U.S. patent number, and accession number in the NASA system