3,538 research outputs found
Description of a digital computer simulation of an Annular Momentum Control Device (AMCD) laboratory test model
A description of a digital computer simulation of an Annular Momentum Control Device (AMCD) laboratory model is presented. The AMCD is a momentum exchange device which is under development as an advanced control effector for spacecraft attitude control systems. The digital computer simulation of this device incorporates the following models: six degree of freedom rigid body dynamics; rim warp; controller dynamics; nonlinear distributed element axial bearings; as well as power driver and power supply current limits. An annotated FORTRAN IV source code listing of the computer program is included
Signatures of Hong-Ou-Mandel Interference at Microwave Frequencies
Two-photon quantum interference at a beam splitter, commonly known as
Hong-Ou-Mandel interference, was recently demonstrated with
\emph{microwave-frequency} photons by Lang \emph{et
al.}\,\cite{lang:microwaveHOM}. This experiment employed circuit QED systems as
sources of microwave photons, and was based on the measurement of second-order
cross-correlation and auto-correlation functions of the microwave fields at the
outputs of the beam splitter. Here we present the calculation of these
correlation functions for the cases of inputs corresponding to: (i) trains of
\emph{pulsed} Gaussian or Lorentzian single microwave photons, and (ii)
resonant fluorescent microwave fields from \emph{continuously-driven} circuit
QED systems. The calculations include the effects of the finite bandwidth of
the detection scheme. In both cases, the signature of two-photon quantum
interference is a suppression of the second-order cross-correlation function
for small delays. The experiment described in Ref.
\onlinecite{lang:microwaveHOM} was performed with trains of \emph{Lorentzian}
single photons, and very good agreement between the calculations and the
experimental data was obtained.Comment: 11 pages, 3 figure
Recommended from our members
The role of endo-β-1,4-glucanase in strawberry fruit development
The ripening of strawberry fruit is characterized by changes in the composition and structure of the cell wall polysaccharides leading to textural changes and loss of firmness of the fruit. An endo-β-1,4-glucanase (EGase) was purified from ripe strawberry (Fragaria x ananassa Duch.) fruit using cellulose affinity chromatography. The purified enzyme gave a single protein band of 54 kDa on sodium dqdecyl sulphate- polyaciylamide gel electrophoresis. A 25 amino acid N-terminal sequence showed strong homology with the proteins encoded by recently identified EGase genes from different strawberry cultivars and from Arabidopsis, pepper and tomato. The enzyme specifically cleaved the β-1,4-glucosyl linkages of xyloglucan but was unable to hydrolyze those of insoluble cellulose. The pH optimum and Km of the enzyme against the artificial substrate carboxymethylcellulose (CMC) were pH 5.0 to 7.0 and 1.3 mg ml-1 respectively. A cDNA of the corresponding ripening-enhanced, fruit-specific gene, cel1, was isolated from a ripe fruit cDNA library. This was used to down-regulate cel1 expression in transgenic strawberry plants in order to assess the potential role(s) played by Cel1 during strawberry fruit ripening. In several transgenic lines, Cel1 mRNA was suppressed to undetectable levels in ripe fruit. However, EGase activity and firmness of these fruit were indistinguishable from control fruit. A second strawberry EGase gene, cel2, is also expressed in ripening fruit and this presence has prevented specific down- regulation of cel1 from revealing its role in fruit softening. Southern analysis of cel1 and cel2 revealed the presence of related sequences in the strawberry genome indicating a small multigene family, consistent with the isolation of two different EGase cDNAs from strawberry
Propagation of sound through a sheared flow
Sound generated in a moving fluid must propagate through a shear layer in order to be measured by a fixed instrument. These propagation effects were evaluated for noise sources typically associated with single and co-flowing subsonic jets and for subcritical flow over airfoils in such jets. The techniques for describing acoustic propagation fall into two categories: geometric acoustics and wave acoustics. Geometric acoustics is most convenient and accurate for high frequency sound. In the frequency range of interest to the present study (greater than 150 Hz), the geometric acoustics approach was determined to be most useful and practical
Changes in Child Symptomatology Associated with Animal-Assisted Therapy
This study examined the changes in symptoms of anxiety, depression, and social ill dysfunction associated with a history of child trauma after adding animal-assisted therapy (AAT) to conventional psychotherapy for adolescents living in a residential treatment facility in northern California. Using a quasiexperimental design, participants were followed over a period of nine weeks, with both groups completing the State-Trait Anxiety Inventory, the Beck Depression Inventory , an abbreviated version of the Beck Depression Inventory, and the Youth Self-Report, and residential staff completing the Youth Outcome Questionnaire at three time points. In addition, the treatment group completed state anxiety and depression assessments before and after receiving the adjunctive AAT at each of these assessment points. Analyses suggest that the treatment group mean depression score was lower than the control group\u27s score, but only at week 5. The significance of group differences in mean anxiety at posttest assessments could not be determined due to pretreatment group differences. Within-subjects analyses suggest that the treatment group experienced significant reductions in mean state anxiety scores after receiving the AAT at each of the three assessment points over the nine weeks. These reductions in anxiety were not, however, maintained between assessments. No significant changes in self- or other-reported social behaviors were found. Implications of these findings are discussed as well as suggestions for future research
Analysis and simulation of a magnetic bearing suspension system for a laboratory model annular momentum control device
A linear analysis and the results of a nonlinear simulation of a magnetic bearing suspension system which uses permanent magnet flux biasing are presented. The magnetic bearing suspension is part of a 4068 N-m-s (3000 lb-ft-sec) laboratory model annular momentum control device (AMCD). The simulation includes rigid body rim dynamics, linear and nonlinear axial actuators, linear radial actuators, axial and radial rim warp, and power supply and power driver current limits
Continuous quantum non-demolition measurement of Fock states of a nanoresonator using feedback-controlled circuit QED
We propose a scheme for the quantum non-demolition (QND) measurement of Fock
states of a nanomechanical resonator via feedback control of a coupled circuit
QED system. A Cooper pair box (CPB) is coupled to both the nanoresonator and
microwave cavity. The CPB is read-out via homodyne detection on the cavity and
feedback control is used to effect a non-dissipative measurement of the CPB.
This realizes an indirect QND measurement of the nanoresonator via a
second-order coupling of the CPB to the nanoresonator number operator. The
phonon number of the Fock state may be determined by integrating the stochastic
master equation derived, or by processing of the measurement signal.Comment: 5 pages, 3 figure
AE-C attitude determination and control prelaunch analysis and operations plan
A description of attitude control support being supplied by the Mission and Data Operations Directorate is presented. Included are descriptions of the computer programs being used to support the missions for attitude determination, prediction, and control. In addition, descriptions of the operating procedures which will be used to accomplish mission objectives are provided
HISTOLOGICAL CHANGES FOLLOWING OVARIECTOMY IN MICE : I. dba HIGH TUMOR STRAIN
1. In dba mice ovariectomized at birth the vagina, uterus, and mammary glands showed a gradual recovery from the castrate state, and finally reached the stage which they presumably can attain only under the influence of estrogenic hormones. Tumors of the mammary glands developed in 37 animals, of 75 examined, between the ages of 14 and 28 months (3 adenomas and 34 carcinomas). 2. As ovarian regeneration had not taken place the probability that estrogen originated in some other organ in the absence of the ovaries is suggested. 3. The consistent nodular hyperplasia of the suprarenal cortex and close morphological similarity of cells of these nodules to lutein-like cells of the ovaries points to the abnormal suprarenals as possible sources of the estrogenic hormones
- …