8,922 research outputs found
Integrated sensors for robotic laser welding
A welding head is under development with integrated sensory systems for robotic laser welding applications. Robotic laser welding requires sensory systems that are capable to accurately guide the welding head over a seam in three-dimensional space and provide information about the welding process as well as the quality of the welding result. In this paper the focus is on seam tracking. It is difficult to measure three-dimensional parameters of a ream during a robotic laser welding task, especially when sharp corners are present. The proposed sensory system is capable to provide the three dimensional parameters of a seam in one measurement and guide robots over sharp corners
Money and Credit Factors
The authors introduce new measures of important underlying macroeconomic phenomena that affect the financial side of the economy. These measures are calculated using the time-series factor analysis (TSFA) methodology introduced in Gilbert and Meijer (2005). The measures appear to be both more interesting and more robust to the effects of financial innovations than traditional aggregates. The general ideas set out in Gilbert and Pichette (2003) are pursued, but the improved estimation methods of TSFA are used. Furthermore, four credit aggregates are added to the components of the monetary aggregates, resulting in the possibility of extracting more common factors.Credit and credit aggregates; Monetary aggregates; Econometric and statistical methods
Long Proteins with Unique Optimal Foldings in the H-P Model
It is widely accepted that (1) the natural or folded state of proteins is a
global energy minimum, and (2) in most cases proteins fold to a unique state
determined by their amino acid sequence. The H-P (hydrophobic-hydrophilic)
model is a simple combinatorial model designed to answer qualitative questions
about the protein folding process. In this paper we consider a problem
suggested by Brian Hayes in 1998: what proteins in the two-dimensional H-P
model have unique optimal (minimum energy) foldings? In particular, we prove
that there are closed chains of monomers (amino acids) with this property for
all (even) lengths; and that there are open monomer chains with this property
for all lengths divisible by four.Comment: 22 pages, 18 figure
Laser radiation pressure slowing of a molecular beam
There is substantial interest in producing samples of ultracold molecules for
possible applications in quantum computation, quantum simulation of condensed
matter systems, precision measurements, controlled chemistry, and high
precision spectroscopy. A crucial step to obtaining large samples of ultracold,
trapped molecules is developing a means to bridge the gap between typical
molecular source velocities (~150-600 m/s) and velocities for which trap
loading or confinement is possible (~5-20 m/s). Here we show deceleration of a
beam of neutral strontium monofluoride (SrF) molecules using radiative force.
Under certain conditions, the deceleration results in a substantial flux of
molecules with velocities <50 m/s. The observed slowing, from ~140 m/s,
corresponds to scattering ~10000 photons. We also observe longitudinal velocity
compression under different conditions. Combined with molecular laser cooling
techniques, this lays the groundwork to create slow and cold molecular beams
suitable for trap loading.Comment: 7 pages, 7 figures. Supplementary material updated
Nature of Ar bonding to small Co_n^+ clusters and its effect on the structure determination by far-infrared absorption spectroscopy
Far-infrared vibrational spectroscopy by multiple photon dissociation has
proven to be a very useful technique for the structural fingerprinting of small
metal clusters. Contrary to previous studies on cationic V, Nb and Ta clusters,
measured vibrational spectra of small cationic cobalt clusters show a strong
dependence on the number of adsorbed Ar probe atoms, which increases with
decreasing cluster size. Focusing on the series Co_4^+ to Co_8^+ we therefore
use density-functional theory to analyze the nature of the Ar-Co_n^+ bond and
its role for the vibrational spectra. In a first step, energetically low-lying
isomer structures are identified through first-principles basin-hopping
sampling runs and their vibrational spectra computed for a varying number of
adsorbed Ar atoms. A comparison of these fingerprints with the experimental
data enables in some cases a unique assignment of the cluster structure.
Independent of the specific low-lying isomer, we obtain a pronounced increase
of the Ar binding energy for the smallest cluster sizes, which correlates
nicely with the observed increased influence of the Ar probe atoms on the IR
spectra. Further analysis of the electronic structure motivates a simple
electrostatic picture that not only explains this binding energy trend, but
also why the influence of the rare-gas atom is much stronger than in the
previously studied systems.Comment: 12 pages including 10 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.htm
Новые определения глубинного теплового потока Земли в Карпатском регионе
Встановлено нові значення глибинного теплового потоку Землі (ТП) у 44 пунктах та проведено незалежні повторні визначення ТП у 45 пунктах Карпатського регіону на родовищах нафти і газу. Визначено аномалії, які вірогідно пов'язані з підйомом глибинних флюїдів.The new values of deep heat flow (HF) are studied at 44 points, and the independent re-determinations of HF are executed at 45 points of the Carpathian region in the oil and gas fields. Anomalies presumably associated with the rise of deep fluids are found
Activation of M-phase-specific histone H1 kinase by modification of the phosphorylation of its p34cdc2 and cyclin components
An M-phase-specific histone H1 kinase (H1K) has been described in a wide variety of eukaryotic cell types undergoing the G2/M transition in the cell division cycle. We have used p13suc1-Sepharose affinity chromatography to purify H1K to near homogeneity from matured starfish oocytes. A yield of 67% was obtained. Active H1K behaves as a 90- to 100-kD protein and appears to be constituted of equimolar amounts of cyclin and p34cdc2. The p34cdc2 subunit becomes tyrosine-dephosphorylated as the H1K is activated during entry of the oocytes into M phase, whereas the cyclin subunit is reciprocally phosphorylated. Acid phosphatase treatment of inactive p34cdc2/cyclin complex induces p34cdc2 dephosphorylation and three- to eightfold stimulation of the enzyme activity. These results suggest that active M-phase-specific H1K is constituted of both dephosphorylated p34cdc2 and phosphorylated cyclin
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