This paper presents the results of in-orbit commissioning of the first Czech technological CubeSat satellite of VZLUSAT-1. The 2U nanosatellite was designed and built during the 2013 to 2016 period. ...It was successfully launched into Low Earth Orbit of 505 km altitude on June 23, 2017 as part of international mission QB50 onboard a PSLV C38 launch vehicle. The satellite was developed in the Czech Republic by the Czech Aerospace Research Centre, in cooperation with Czech industrial partners and universities. The nanosatellite has three main payloads. The housing is made of a composite material which serves as a structural and radiation shielding material. A novel miniaturized X-Ray telescope with lobster-eye optics and an embedded Timepix detector represents the CubeSat’s scientific payload. The telescope has a wide field of view. VZLUSAT-1 also carries the FIPEX scientific instrument as part of the QB50 mission for measuring the molecular and atomic oxygen concentration in the upper atmosphere.
This paper is devoted to the proposal of a highly efficient symbol synchronization subsystem for Software Defined Radio. The proposed feedback phase-locked loop timing synchronizer is suitable for ...parallel implementation on an FPGA. The polyphase FIR filter simultaneously performs matched-filtering and arbitrary interpolation between acquired samples. Determination of the proper sampling instant is achieved by selecting a suitable polyphase filterbank using a derived index. This index is determined based on the output either the Zero-Crossing or Gardner Timing Error Detector. The paper will extensively focus on simulation of the proposed synchronization system. On the basis of this simulation, a complete, fully pipelined VHDL description model is created. This model is composed of a fully parallel polyphase filterbank based on distributed arithmetic, timing error detector and interpolation control block. Finally, RTL synthesis on an Altera Cyclone IV FPGA is presented and resource utilization in comparison with a conventional model is analyzed.
The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy s=8 TeV based on a high-statistics data sample obtained with ...the β⁎=90 m optics. Both the statistical and systematic uncertainties remain below 1%, except for the t-independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027<|t|<0.2 GeV2 with a significance greater than 7 σ. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. Using them for the differential cross-section extrapolation to t=0, and further applying the optical theorem, yields total cross-section estimates of (101.5±2.1) mb and (101.9±2.1) mb, respectively, in agreement with previous TOTEM measurements.
This paper presents a very efficient design procedure for a high-performance microstrip lowpass filter (LPF). Unlike many other sophisticated design methodologies of microstrip LPFs, which contain ...complicated configurations or even over-engineering in some cases, this paper presents a straightforward design procedure to achieve some of the best performance of this class of microstrip filters. The proposed filter is composed of three different polygonal-shaped resonators, two of which are responsible for stopband improvement, and the third resonator is designed to enhance the selectivity of the filter. A holistic performance assessment of the proposed filter is presented using a Figure of Merit (FOM) and compared with some of the best filters from the same class, highlighting the superiority of the proposed design. A prototype of the proposed filter was fabricated and tested, showing a 3-dB cut-off frequency (fc) at 1.27 GHz, having an ultrawide stopband with a suppression level of 25 dB, extending from 1.6 to 25 GHz. The return loss and the insertion loss of the passband are better than 20 dB and 0.25 dB, respectively. The fabricated filter has a high FOM of 76331, and its lateral size is 22.07 mm × 7.57 mm.
The TOTEM experiment at the LHC has performed the first measurement at
s
=
13
TeV
of the
ρ
parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at
t
=
0
, obtaining the ...following results:
ρ
=
0.09
±
0.01
and
ρ
=
0.10
±
0.01
, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the
ρ
measurement, combined with the TOTEM total cross-section measurements in an energy range larger than
10
TeV
(from 2.76 to
13
TeV
), has implied the exclusion of all the models classified and published by COMPETE. The
ρ
results obtained by TOTEM are compatible with the predictions, from other theoretical models both in the Regge-like framework and in the QCD framework, of a crossing-odd colourless 3-gluon compound state exchange in the
t
-channel of the proton–proton elastic scattering. On the contrary, if shown that the crossing-odd 3-gluon compound state
t
-channel exchange is not of importance for the description of elastic scattering, the
ρ
value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-|
t
| reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton–proton cross-section measurement
σ
tot
=
(
110.3
±
3.5
)
mb
, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields
σ
tot
=
(
110.5
±
2.4
)
mb
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The TOTEM collaboration has measured the proton–proton total cross section at
s
=
13
TeV
with a luminosity-independent method. Using dedicated
β
∗
=
90
m
beam optics, the Roman Pots were inserted ...very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton–proton cross section is
σ
tot
=
(
110.6
±
3.4
) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections:
σ
el
=
(
31.0
±
1.7
)
mb
and
σ
inel
=
(
79.5
±
1.8
)
mb
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The TOTEM experiment at the CERN LHC has measured elastic proton–proton scattering at the centre-of-mass energy
s
=
8
TeV and four-momentum transfers squared, |
t
|, from
6
×
10
-
4
to 0.2 GeV
2
. ...Near the lower end of the
t
-interval the differential cross-section is sensitive to the interference between the hadronic and the electromagnetic scattering amplitudes. This article presents the elastic cross-section measurement and the constraints it imposes on the functional forms of the modulus and phase of the hadronic elastic amplitude. The data exclude the traditional Simplified West and Yennie interference formula that requires a constant phase and a purely exponential modulus of the hadronic amplitude. For parametrisations of the hadronic modulus with second- or third-order polynomials in the exponent, the data are compatible with hadronic phase functions giving either central or peripheral behaviour in the impact parameter picture of elastic scattering. In both cases, the
ρ
-parameter is found to be
0.12
±
0.03
. The results for the total hadronic cross-section are
σ
tot
=
(
102.9
±
2.3
)
mb and
(
103.0
±
2.3
)
mb for central and peripheral phase formulations, respectively. Both are consistent with previous TOTEM measurements.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We describe an analysis comparing the p (p) over bar elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in pp collisions as measured by the TOTEM ...Collaboration at 2.76, 7, 8, and 13 TeVusing a model-independent approach. The TOTEM cross sections, extrapolated to a center-of-mass energy of root s = 1.96 TeV, are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the pp cross section. The two data sets disagree at the 3.4s level and thus provide evidence for the t-channel exchange of a colorless, C-odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same C-odd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic strong interaction scattering amplitude in pp scattering for which the significance is between 3.4s and 4.6s. The combined significance is larger than 5 sigma and is interpreted as the first observation of the exchange of a colorless, C-odd gluonic compound.
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