Similar Energy Region Research Articles

Cloud-based improved Monte Carlo localization algorithm with robust orientation estimation for mobile robots

Purpose This paper aims to demonstrate a cloud-based version of the improved Monte Carlo localization algorithm with robust orientation estimation (IMCLROE). The purpose of this system is to increase the accuracy and efficiency of indoor robot localization. Design/methodology/approach The cloud-based IMCLROE is constructed with a cloud–client architecture that distributes computation between servers and a client robot. The system operates in two phases: in the offline phase, two maps are built under the MapReduce framework. This framework allows parallel and even distribution of map information to a cloud database in pre-described formats. In the online phase, an Apache HBase is adopted to calculate a pose in-memory and promptly send the result to the client robot. To demonstrate the efficiency of the cloud-based IMCLROE, a two-step experiment is conducted: first, a mobile robot implemented with a non-cloud IMCLROE and a UDOO single-board computer is tested for its efficiency on pose-estimation accuracy. Then, a cloud-based IMCLROE is implemented on a cloud–client architecture to demonstrate its efficiency on both pose-estimation accuracy and computation ability. Findings For indoor localization, the cloud-based IMCLROE is much more effective in acquiring pose-estimation accuracy and relieving computation burden than the non-cloud system. Originality/value The cloud-based IMCLROE achieves efficiency of indoor localization by using three innovative strategies: firstly, with the help of orientation estimation and weight calculation (OEWC), the system can sort out the best orientation. Secondly, the system reduces computation burden with map pre-caching. Thirdly, the cloud–client architecture distributes computation between the servers and client robot. Finally, the similar energy region (SER) technique provides a high-possibility region to the system, allowing the client robot to locate itself in a short time.

Spin physics and TMD studies at A Fixed-Target ExpeRiment at the LHC (AFTER@LHC)

We report on the opportunities for spin physics and Transverse-Momentum Dependent distribution (TMD) studies at a future multi-purpose fixed-target experiment using the proton or lead ion LHC beams extracted by a bent crystal. The LHC multi-TeV beams allow for the most energetic fixed-target experiments ever performed, opening new domains of particle and nuclear physics and complementing that of collider physics, in particular that of RHIC and the EIC projects. The luminosity achievable with AFTER@LHC using typical targets would surpass that of RHIC by more that 3 orders of magnitude in a similar energy region. In unpolarised proton-proton collisions, AFTER@LHC allows for measurements of TMDs such as the Boer-Mulders quark distributions, the distribution of unpolarised and linearly polarised gluons in unpolarised protons. Using the polarisation of hydrogen and nuclear targets, one can measure transverse single-spin asymmetries of quark and gluon sensitive probes, such as, respectively, Drell-Yan pair and quarkonium production. The fixed-target mode has the advantage to allow for measurements in the target-rapidity region, namely at large x^uparrow in the polarised nucleon. Overall, this allows for an ambitious spin program which we outline here.

Elastic scattering of protons from15N

Background: Resonances observed through elastic scattering of protons on ${}^{15}$N can provide information about the partial widths, spin parities, and energies of excited states in ${}^{16}$O near the proton separation energy. This is the same energy region important for the nuclear astrophysics reactions ${}^{15}$N${(p,\ensuremath{\gamma})}^{16}$O and ${}^{15}$N${(p,\ensuremath{\alpha})}^{12}$C. While previous measurements have been made, they are limited in scope, especially in their angular coverage. Purpose: Obtain additional ${}^{15}$N${(p,p)}^{15}$N reaction data which can be used in a global multiple-channel $R$-matrix analysis of the ${}^{16}$O compound nucleus in order to better constrain the level parameters of states which contribute to the reaction ${}^{15}$N${(p,\ensuremath{\gamma})}^{16}$O. Methods: Measure the excitation functions of ${}^{15}$N${(p,p)}^{15}$N over an energy range from ${E}_{p}$ $=$ 0.6 to 1.8 MeV at laboratory angles of 90${}^{\ensuremath{\circ}}$, 105${}^{\ensuremath{\circ}}$, 135${}^{\ensuremath{\circ}}$, 150${}^{\ensuremath{\circ}}$, and 165${}^{\ensuremath{\circ}}$. The reaction ${}^{15}$N${(p,{\ensuremath{\alpha}}_{0})}^{12}$C was measured concurrently. Results: Ratios of the excitation functions were extracted from the yield data. Resonances were identified in the yield ratio data which correspond to previously reported levels in ${}^{16}$O. An $R$-matrix analysis, which fits the present data as well as previous measurements from the literature simultaneously, finds reasonable agreement between the current measurements and those in the literature. Conclusions: The additional data from this measurement will be combined with previous literature data in a comprehensive $R$-matrix analysis of reactions which populate ${}^{16}$O over a similar energy region.

Self-adaptive Monte Carlo localization for mobile robots using range finders

SUMMARYIn order to achieve the autonomy of mobile robots, effective localization is a necessary prerequisite. In this paper, we propose an improved Monte Carlo localization algorithm using self-adaptive samples (abbreviated as SAMCL). By employing a pre-caching technique to reduce the online computational burden, SAMCL is more efficient than the regular MCL. Further, we define the concept of similar energy region (SER), which is a set of poses (grid cells) having similar energy with the robot in the robot space. By distributing global samples in SER instead of distributing randomly in the map, SAMCL obtains a better performance in localization. Position tracking, global localization and the kidnapped robot problem are the three sub-problems of the localization problem. Most localization approaches focus on solving one of these sub-problems. However, SAMCL solves all the three sub-problems together, thanks to self-adaptive samples that can automatically separate themselves into a global sample set and a local sample set according to needs. The validity and the efficiency of the SAMCL algorithm are demonstrated by both simulations and experiments carried out with different intentions. Extensive experimental results and comparisons are also given in this paper.

R-matrix calculation of low-energy electron collisions with phosphoric acid

Electron collision calculations are performed on two conformers of H3PO4, a weakly dipolar form with all OH groups pointing up and a strongly dipolar form where one OH group points down. Strong evidence is found for a broad shape resonance at about 7 eV for both conformers, although the precise parameters of this resonance are sensitive to the details of the target wavefunction used. Ten-state close-coupling calculations suggest the presence of very narrow Feshbach resonances in a similar energy region. Again both conformers behave similarly. Elastic and electronically inelastic cross sections are calculated for both conformers.

Optical properties ofRNi2B2C(R=Y,Tb,Er,Dy)

The optical properties of single crystals of $R{\mathrm{Ni}}_{2}{\mathrm{B}}_{2}\mathrm{C}$ $(R=\mathrm{Y},\mathrm{}\mathrm{T}\mathrm{b},\mathrm{}\mathrm{Er},$ and Dy) were measured between 1.7 and 5.2 eV at room temperature using a spectroscopic ellipsometer. The spectra for all compounds are similar and the peak positions appear in a similar energy region. The similarity of the spectra of $R{\mathrm{Ni}}_{2}{\mathrm{B}}_{2}\mathrm{C}$ $(R=\mathrm{T}\mathrm{b},\mathrm{}\mathrm{E}\mathrm{r},\mathrm{}\mathrm{Dy})$ to that of ${\mathrm{YNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}$ indicates that the rare-earth $4f$ states are not actively involved in the optical transitions.

Effect of symmetry breaking on statistical distributions

The quantum numbers of states in 30P have been determined for over 100 states from the ground state to 8 MeV. Previous measurements had provided complete spectroscopy for over 150 states in 26Al in a similar energy region. These N = Z = odd nuclei have the property that states of isospin T = 0 and T = 1 coexist from the ground state. Isospin is approximately conserved in these nuclei. Since the energy E, spin J, parity π, and isospin T are known for every level, these data provide a unique opportunity to test the effect of symmetry breaking on the level statistics and on the transition strength distributions. The level statistics are strongly affected by the small symmetry breaking, in agreement with predictions of Random Matrix Theory (RMT). In 26Al the transition strength distributions differ from the standard Porter-Thomas distribution; deviations at a weaker level also appear in 30P. Until very recently there were no theoretical predictions for the effect of symmetry breaking on the transitions. Recent RMT calculations predict a deviation from the Porter-Thomas distribution, in qualitative agreement with the measurements.

Measurements of the neutron transmission and capture cross sections inPb204

High resolution neutron transmission measurements have been performed on $^{204}\mathrm{Pb}$ in the energy interval $E=0.4\ensuremath{-}105$ keV. The transmission data were analyzed using a multilevel $R$-matrix code to deduce resonance parameters. Previously obtained neutron capture data were reanalyzed in the interval 2.6-86 keV. Values of $\frac{G{\ensuremath{\Gamma}}_{\mathrm{n}}{\ensuremath{\Gamma}}_{\ensuremath{\gamma}}}{\ensuremath{\Gamma}}$ were determined from the capture data. For those resonances where ${\ensuremath{\Gamma}}_{\mathrm{n}}$ could be determined from the transmission data, the capture data were analyzed to extract ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}}$. Our results yield an average capture for a stellar temperature $kT=30$ keV of 89.5\ifmmode\pm\else\textpm\fi{}4.5 mb. The $s$-wave level density for $^{205}\mathrm{Pb}$ corresponding to the neutron energy range investigated (i.e., $E\ensuremath{\sim}105$ keV) relative to that for $^{207}\mathrm{Pb}$ (which has about the same neutron separation energy) is greater by about a factor of 10. The average $s$-wave strength function in this energy region is determined as ${S}_{0}=0.93\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. This is an order of magnitude greater than that for a similar energy region in $^{206}\mathrm{Pb}$ + n where a doorway is observed at $E\ensuremath{\sim}500$ keV. However, the strength function in the initial $E=0\ensuremath{-}100$ keV in $^{204}\mathrm{Pb}$ + n is almost identical to the average value of that for $^{206}\mathrm{Pb}$ + n when the averaging interval for the latter is taken as ${E}_{\mathrm{n}}\ensuremath{\approx}0\ensuremath{-}1000$ keV (i.e., over the doorway state). This suggests that the $s$-wave doorway state observed in the higher mass lead isotopes is completely mixed with "background" states in $^{205}\mathrm{Pb}$, and most likely no intermediate structure will be observed in the $s$-wave strength function for the $^{204}\mathrm{Pb}$ + n reaction.

Investigation of reaction 84 MeV/u C 12 + Pb 208 by using CR-39 plastic track detector

ABSTRACT The plastic track detector CR-39 was used in investigation of 84 MeV/u C12 + Pb208 reaction. In our experiment we employed the 4π - geometry technique and the method of successive etching. Presented are cross sections and forward-backward ratios for fission and other reactions. Comparisons are made with results obtained with other projectiles in similar energy region.

Spectroscopy, chemistry and catalysis of metal atoms, metal dimers and metal clusters

This paper starts with the experimental realization of trapped silver atoms in various matrix supports, with emphasis placed on optical absorption, emission and e.s.r. spectroscopic properties. Special attention is devoted to ground- and excited-state silver atom interactions with the surrounding matrix cage of atoms, particularly with respect to the recently discovered phenomenon of light-induced diffusion and aggregation of silver atoms to small, precisely defined silver clusters. Various aspects and applications of photodiffusion methods are highlighted and some pertinent comparisons are made with metal concentration and bulk annealing approaches as alternatives to controlled metal nucleation. This will lead to the embryonic clusters Ag2 and Ag3 for which there now exists considerable spectroscopic, photochemical and theoretical information. Silver-containing bimetallic clusters, generated either by metal concentration deposition or photoaggregation methods, will be a natural extension to the Ag2,3 presentation; their relevance to bimetallic cluster catalysts will be briefly contemplated. The concept of generating anionic silver clusters by Na/Ag photoionization methods will be briefly described, with reference to the parent Ag– anion. In considering the higher silver clusters, one is now in a position to evaluate experimentally the genesis of silver nucleation from the stage of an isolated silver atom, through to a six-atom array and to higher, less well defined aggregates. With these data one can attempt to track the evolving optical and e.s.r. properties by reference to the build-up of cluster electronic states calculated by way of SCF-Xα-SW molecular-orbital procedures for assumed cluster geometries. The observation of rudimentary interband transitions of silver clusters in the range 6-13 atoms, that absorb in a similar energy region to the collective electronic excitations associated with plasmon absorption of silver microcrystallites, simultaneously with the evolution of conduction electron spin resonance absorption, whose observed linewidths and g-shifts conform to the theoretical predictions of Kubo and Kawabata, can in principle provide a valuable criterion on which to judge the atomic composition at which optical–electronic characteristics of silver aggregates transform from those of the molecular to the bulk state. Future directions in diatomic-metal and metal-cluster chemistry are briefly contemplated in the light of recent break-throughs with ambient-temperature metal-vapour–liquid-polymer techniques and the discovery of polymer-supported, very low nuclearity metal cluster, generated and stable at, or very close to, room temperature.