10,598 research outputs found
Space Shuttle separate-surface control-system study
A control system concept is presented that produces proportional control of yaw moment for the space shuttle from early entry to Mach 2 with only software modifications of the vehicle. It uses separate deflections of the inboard and outboard elevon surfaces and is evaluated, by determining the maximum static yawing moment available by considering the deflection limits of the elevon surfaces. A proportional moment slightly in excess of that produced by the most effective reaction control system (RCS) jet for yaw control can be obtained. In addition to the static moment study, a control law is designed which is intended to produce desired flying qualities
Ocean services user needs assessment. Volume 1: Survey results, conclusions and recommendations
An interpretation of environmental information needs of marine users, derived from a direct contact survey of eight important sectors of the marine user community is presented. Findings of the survey and results and recommendations are reported. The findings consist of specific and quantized measurement and derived product needs for each sector and comparisons of these needs with current and planned NOAA data and services. The following supportive and reference material are examined: direct contact interviews with industry members, analyses of current NOAA data gathering and derived product capabilities, evaluations of new and emerging domestic and foreign satellite data gathering capabilities, and a special commercial fishing survey conducted by the Jet Propulsion Laboratory (JPL)
Chow's theorem and universal holonomic quantum computation
A theorem from control theory relating the Lie algebra generated by vector
fields on a manifold to the controllability of the dynamical system is shown to
apply to Holonomic Quantum Computation. Conditions for deriving the holonomy
algebra are presented by taking covariant derivatives of the curvature
associated to a non-Abelian gauge connection. When applied to the Optical
Holonomic Computer, these conditions determine that the holonomy group of the
two-qubit interaction model contains . In particular, a
universal two-qubit logic gate is attainable for this model.Comment: 13 page
Important factors in the maximum likelihood analysis of flight test maneuvers
The information presented is based on the experience in the past 12 years at the NASA Dryden Flight Research Center of estimating stability and control derivatives from over 3500 maneuvers from 32 aircraft. The overall approach to the analysis of dynamic flight test data is outlined. General requirements for data and instrumentation are discussed and several examples of the types of problems that may be encountered are presented
Spontaneous creation of non-zero angular momentum modes in tunnel-coupled two-dimensional degenerate Bose gases
We investigate the dynamics of two tunnel-coupled two-dimensional degenerate
Bose gases. The reduced dimensionality of the clouds enables us to excite
specific angular momentum modes by tuning the coupling strength, thereby
creating striking patterns in the atom density profile. The extreme sensitivity
of the system to the coupling and initial phase difference results in a rich
variety of subsequent dynamics, including vortex production, complex
oscillations in relative atom number and chiral symmetry breaking due to
counter-rotation of the two clouds.Comment: 7 pages, 5 figure
Overcoming the su(2^n) sufficient condition for the coherent control of n-qubit systems
We study quantum systems with even numbers N of levels that are completely
state-controlled by unitary transformations generated by Lie algebras
isomorphic to sp(N) of dimension N(N+1)/2. These Lie algebras are smaller than
the respective su(N) with dimension N^2-1. We show that this reduction
constrains the Hamiltonian to have symmetric energy levels. An example of such
a system is an n-qubit system. Using a geometric representation for the quantum
wave function of a finite system, we present an explicit example that shows a
two-qubit system can be controlled by the elements of the Lie algebra sp(4)
(isomorphic to spin(5) and so(5)) with dimension ten rather than su(4) with
dimension fifteen. These results enable one to envision more efficient
algorithms for the design of fields for quantum-state engineering, and they
provide more insight into the fundamental structure of quantum control.Comment: 13 pp., 2 figure
Role of Angiotensin II in Hemorrhagic Hypotension in the Rat
Author Institution: Department of Physiology, Wright State UniversityThe purpose of this study was to evaluate the role of the renin-angiotensin system in the acute regulation of blood pressure following hemorrhage in the anesthetized rat. Eleven Sprague-Dawley rats were anesthetized with sodium pentobarbital. After control blood pressure recordings from the femoral artery were made, the rats were hemorrhaged 6 ml/kg body weight. Forty minutes after hemorrhage, the Angiotensin II antagonist, l-SAR-8-ALA-Angiotensin II (saralasin), was infused (10 /Ltg/min/kg) for 35 min. Hemorrhage resulted in a 53% decrease in blood pressure which recovered to 82% of the control blood pressure in 40 minutes. Infusion of saralasin resulted in a 24% decrease (p <0.01) in blood pressure within 15 min. Recovery from saralasin infusion occurred within 10 min as blood pressure increased back to control values. A second group of 5 rats was not hemorrhaged but was infused with saralasin. There were no significant changes in blood pressure; although, a tendency to decrease was noted reflecting the increase in plasma renin activity which occurs with anesthesia. It was concluded that the renin-angiotensin system can respond rapidly to a hypotensive event and aid in the restoration of blood pressure within minutes
Long Range Planning for the Environment Circa 2000
The environment that the Armed Services share in the year 2000 will be shaped largely by today\u27s societal trends—economic, political, demographic, technological, and sociological phenomena
Time complexity and gate complexity
We formulate and investigate the simplest version of time-optimal quantum
computation theory (t-QCT), where the computation time is defined by the
physical one and the Hamiltonian contains only one- and two-qubit interactions.
This version of t-QCT is also considered as optimality by sub-Riemannian
geodesic length. The work has two aims: one is to develop a t-QCT itself based
on physically natural concept of time, and the other is to pursue the
possibility of using t-QCT as a tool to estimate the complexity in conventional
gate-optimal quantum computation theory (g-QCT). In particular, we investigate
to what extent is true the statement: time complexity is polynomial in the
number of qubits if and only if so is gate complexity. In the analysis, we
relate t-QCT and optimal control theory (OCT) through fidelity-optimal
computation theory (f-QCT); f-QCT is equivalent to t-QCT in the limit of unit
optimal fidelity, while it is formally similar to OCT. We then develop an
efficient numerical scheme for f-QCT by modifying Krotov's method in OCT, which
has monotonic convergence property. We implemented the scheme and obtained
solutions of f-QCT and of t-QCT for the quantum Fourier transform and a unitary
operator that does not have an apparent symmetry. The former has a polynomial
gate complexity and the latter is expected to have exponential one because a
series of generic unitary operators has a exponential gate complexity. The time
complexity for the former is found to be linear in the number of qubits, which
is understood naturally by the existence of an upper bound. The time complexity
for the latter is exponential. Thus the both targets are examples satisfyng the
statement above. The typical characteristics of the optimal Hamiltonians are
symmetry under time-reversal and constancy of one-qubit operation, which are
mathematically shown to hold in fairly general situations.Comment: 11 pages, 6 figure
Directional characteristics of lunar thermal emission
Directional characteristics and brightness temperatures of thermal lunar emissio
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