Analysis by Finite Element Method to Redesign a Jointed-Telescopic Crane for Elevation of Personnel

This paper proposes a numerical assessment of a crane for elevation of personnel by finite element analysis, validated with experimental data from constituent components of the crane. The original design of the crane consists of a jointed section of coplanar arms and a telescopic section of collinear arms. As a reference, the standard ANSI/SIA 92.2 was used to determine maximum loads and the consequent effects on the constituent components of the crane. This standard is suitable for crane designs distributed and commercialized in Mexico. The proposed numerical analysis is carried out through a finite element analysis, which is based on the assembly method of kinematic pairs, taking into account dynamic loads and their resulting reaction at each element. The mechanical performance of each component is assessed with the minimal security factor parameter. However, in those components where the MSF was insufficiently in accordance with the standard, a variety of modifications to redesign a given component was proposed. Subsequently, a detailed structural analysis on the proposed redesign was carried out, in which higher security factors were obtained in comparison to the original design. Finally, the numerical results of the proposed redesign were validated through experimental measurements of strain, using strain gauges attached on a crane prototype, which was manufactured according to the proposed redesigned model.Наведено чисельний розрахунок підйомного крана для підняття персоналу на основі скінченноелементного аналізу, підтверджений експериментальними даними по складових його компонентах. Оригінальна модель підйомного крана включає зчленовані секції компланарних стріл і телескопічної секції колінеарних стріл. Максимальні навантаження та іх вплив на складові компоненти підйомного крана визначено згідно зі стандартом ANSI/SIA 92.9, що використовується для моделей підйомного крана, розповсюджених і комерціалізованих у Мексиці. Скінченноелементний аналіз базується на методі складання кінематичних пар з урахуванням динамічного навантаження та їх результуючої реакції на кожен елемент. Механічні характеристики кожного компонента оцінюються за параметром мінімального фактора безпеки. Однак у тих компонентах, де цей фактор не відповідає стандарту, пропонується безліч модифікацій для перепроектування даного компонента. Проведено детальний структурний аналіз запропонованої їх модернізації й отримано більш високі фактори безпеки порівняно з оригінальною моделлю. Чисельні результати запропонованої модернізації підтверджено експериментальними вимірюваннями деформацій при використанні тензодатчиків, установлених на прототипі підйомного крана, який виготовлено згідно із запропонованою перепроектованою моделлю.Представлен численный расчет подъемного крана для поднятия персонала на основе конечноэлементного анализа, подтвержденный экспериментальными данными по составным его компонентам. Оригинальная модель подъемного крана состоит из сочлененных секций компланарных стрел и телескопической секции коллинеарных стрел. Максимальные нагрузки и их влияние на составные компоненты подъемного крана определены согласно стандарту ANSI/SIA 92.2, применяемому для моделей подъемного крана, распространенных и коммерциализированных в Мексике. Конечноэлементный анализ основан на методе сборки кинематических пар с учетом динамических нагрузок и их результирующей реакции на каждый элемент. Механические характеристики каждого компонента оценены по параметру минимального фактора безопасности. Однако в тех компонентах, где этот фактор не соответствует стандарту, предложено множество модификаций для перепроектирования данного компонента. Выполнен также подробный структурный анализ предложенной их модернизации и получены более высокие факторы безопасности по сравнению с оригинальной моделью. Численные результаты предложенной модернизации подтверждены экспериментальными измерениями деформаций при использовании тензодатчиков, установленных на прототипе подъемного крана, который был изготовлен согласно предложенной перепроектированной модели

An improved method for measuring muon energy using the truncated mean of dE/dx

The measurement of muon energy is critical for many analyses in large Cherenkov detectors, particularly those that involve separating extraterrestrial neutrinos from the atmospheric neutrino background. Muon energy has traditionally been determined by measuring the specific energy loss (dE/dx) along the muon's path and relating the dE/dx to the muon energy. Because high-energy muons (E_mu > 1 TeV) lose energy randomly, the spread in dE/dx values is quite large, leading to a typical energy resolution of 0.29 in log10(E_mu) for a muon observed over a 1 km path length in the IceCube detector. In this paper, we present an improved method that uses a truncated mean and other techniques to determine the muon energy. The muon track is divided into separate segments with individual dE/dx values. The elimination of segments with the highest dE/dx results in an overall dE/dx that is more closely correlated to the muon energy. This method results in an energy resolution of 0.22 in log10(E_mu), which gives a 26% improvement. This technique is applicable to any large water or ice detector and potentially to large scintillator or liquid argon detectors.Comment: 12 pages, 16 figure

All-particle cosmic ray energy spectrum measured with 26 IceTop stations

We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, the surface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysis were taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 km^2. The analysis investigated the energy spectrum from 1 to 100 PeV measured for three different zenith angle ranges between 0{\deg} and 46{\deg}. Because of the isotropy of cosmic rays in this energy range the spectra from all zenith angle intervals have to agree. The cosmic-ray energy spectrum was determined under different assumptions on the primary mass composition. Good agreement of spectra in the three zenith angle ranges was found for the assumption of pure proton and a simple two-component model. For zenith angles {\theta} < 30{\deg}, where the mass dependence is smallest, the knee in the cosmic ray energy spectrum was observed between 3.5 and 4.32 PeV, depending on composition assumption. Spectral indices above the knee range from -3.08 to -3.11 depending on primary mass composition assumption. Moreover, an indication of a flattening of the spectrum above 22 PeV were observed.Comment: 38 pages, 17 figure

On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes

The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper. The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II high energy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic

Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

The $B^0$-$\bar B^0$ oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives $\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

Neutrino oscillation studies with IceCube-DeepCore

AbstractIceCube, a gigaton-scale neutrino detector located at the South Pole, was primarily designed to search for astrophysical neutrinos with energies of PeV and higher. This goal has been achieved with the detection of the highest energy neutrinos to date. At the other end of the energy spectrum, the DeepCore extension lowers the energy threshold of the detector to approximately 10 GeV and opens the door for oscillation studies using atmospheric neutrinos. An analysis of the disappearance of these neutrinos has been completed, with the results produced being complementary with dedicated oscillation experiments. Following a review of the detector principle and performance, the method used to make these calculations, as well as the results, is detailed. Finally, the future prospects of IceCube-DeepCore and the next generation of neutrino experiments at the South Pole (IceCube-Gen2, specifically the PINGU sub-detector) are briefly discussed

A search for the decay B+→K+ννˉB^+ \to K^+ \nu \bar{\nu}

We search for the rare flavor-changing neutral-current decay $B^+ \to K^+ \nu \bar{\nu}$ in a data sample of 82 fb$^{-1}$ collected with the {\sl BABAR} detector at the PEP-II B-factory. Signal events are selected by examining the properties of the system recoiling against either a reconstructed hadronic or semileptonic charged-B decay. Using these two independent samples we obtain a combined limit of ${\mathcal B}(B^+ \to K^+ \nu \bar{\nu})<5.2 \times 10^{-5}$ at the 90% confidence level. In addition, by selecting for pions rather than kaons, we obtain a limit of ${\mathcal B}(B^+ \to \pi^+ \nu \bar{\nu})<1.0 \times 10^{-4}$ using only the hadronic B reconstruction method.Comment: 7 pages, 8 postscript figures, submitted to Phys. Rev. Let

High-reflectivity broadband distributed Bragg reflector lattice matched to ZnTe

We report on the realization of a high quality distributed Bragg reflector with both high and low refractive index layers lattice matched to ZnTe. Our structure is grown by molecular beam epitaxy and is based on binary compounds only. The high refractive index layer is made of ZnTe, while the low index material is made of a short period triple superlattice containing MgSe, MgTe, and ZnTe. The high refractive index step of Delta_n=0.5 in the structure results in a broad stopband and the reflectivity coefficient exceeding 99% for only 15 Bragg pairs.Comment: 4 pages, 3 figure

A muon-track reconstruction exploiting stochastic losses for large-scale Cherenkov detectors

IceCube is a cubic-kilometer Cherenkov telescope operating at the South Pole. The main goal of IceCube is the detection of astrophysical neutrinos and the identification of their sources. High-energy muon neutrinos are observed via the secondary muons produced in charge current interactions with nuclei in the ice. Currently, the best performing muon track directional reconstruction is based on a maximum likelihood method using the arrival time distribution of Cherenkov photons registered by the experiment\u27s photomultipliers. A known systematic shortcoming of the prevailing method is to assume a continuous energy loss along the muon track. However at energies >1 TeV the light yield from muons is dominated by stochastic showers. This paper discusses a generalized ansatz where the expected arrival time distribution is parametrized by a stochastic muon energy loss pattern. This more realistic parametrization of the loss profile leads to an improvement of the muon angular resolution of up to 20% for through-going tracks and up to a factor 2 for starting tracks over existing algorithms. Additionally, the procedure to estimate the directional reconstruction uncertainty has been improved to be more robust against numerical errors