Behavior of concrete beams reinforced with FRP during bending

Article describes methods and results of experimental research for strain behavior, crack formation and fracture of concrete beams reinforced with fiber reinforced polymer (FRP) bars during bending moment action. 18 beams (3+3 series) reinforced with glass FRP (GFRP) and basalt (BFRP) 6, 10 and 14 mm in diameter were tested. Deflection in the middle of the beam, concrete and bars strain and ultrasonic transmission time for 4 routes were measured during tests besides visual inspection. Main crack formation occurred at 8-20% of the ultimate load for all beams. Crack formation was transition border to linear (elastic) straining at low bending stiffness. More than 15 times decrease in bending stiffness was seen for beam reinforced with two types of bars 6 mm in diameter compared to initial values. Existence of main cracks and major deflections is not allowed during design of bending elements. However small bending stiffness at linear elastic straining is a positive factor in case of «hard» loading and impact (pulsed) loading. It is possible to prevent structures collapse and people deaths at impact loading and cyclic «hard» loading by permitting crack formation in load bearing structures

Laser-plasma interactions with a Fourier-Bessel Particle-in-Cell method

A new spectral particle-in-cell (PIC) method for plasma modeling is presented and discussed. In the proposed scheme, the Fourier-Bessel transform is used to translate the Maxwell equations to the quasi-cylindrical spectral domain. In this domain, the equations are solved analytically in time, and the spatial derivatives are approximated with high accuracy. In contrast to the finite-difference time domain (FDTD) methods that are commonly used in PIC, the developed method does not produce numerical dispersion, and does not involve grid staggering for the electric and magnetic fields. These features are especially valuable in modeling the wakefield acceleration of particles in plasmas. The proposed algorithm is implemented in the code PLARES-PIC, and the test simulations of laser plasma interactions are compared to the ones done with the quasi-cylindrical FDTD PIC code CALDER-CIRC.Comment: submitted to Phys. Plasma

Anchorage strength and ductility in shear tests

Article shows shear tests results for anchorage using bent foundation bolts 16, 24 and 36 mm in diameter and torque-controlled undercut anchors 12, 16 and 20 mm in diameter. Load-displacement diagrams were acquired for shear loads in static and dynamic cyclic tests in uncracked and cracked concrete. Cyclic loading pattern simulated seismic loads on anchors. Shear loading tests allowed to estimate influence of cracks and cyclic loading on strength and ductility of anchorage

A celestial gamma-ray foreground due to the albedo of small solar system bodies and a remote probe of the interstellar cosmic ray spectrum

We calculate the gamma-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids (MBAs), Jovian and Neptunian Trojan asteroids, and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the gamma-ray albedo for the Main Belt, Trojans, and Kuiper Belt strongly depends on the small-body size distribution of each system. Based on an analysis of the Energetic Gamma Ray Experiment Telescope (EGRET) data we infer that the diffuse emission from the MBAs, Trojans, and KBOs has an integrated flux of less than ~6x10^{-6} cm^{-2} s^{-1} (100-500 MeV), which corresponds to ~12 times the Lunar albedo, and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). If detected by GLAST, it can provide unique direct information about the number of small bodies in each system that is difficult to assess by any other method. Additionally, the KBO albedo flux can be used to probe the spectrum of CR nuclei at close-to-interstellar conditions. The orbits of MBAs, Trojans, and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. Therefore, the asteroid gamma-ray albedo has to be taken into account when analyzing weak gamma-ray sources close to the ecliptic, especially near the Galactic center and for signals at high Galactic latitudes, such as the extragalactic gamma-ray emission. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center.Comment: 10 pages, 5 figures, 1 table, emulateapj.cls; ApJ in press. Calculations extended to include Jovian and Neptunian Trojan groups, and Centaurs, in addition to Main Belt Asteroids and Kuiper Belt Objects. Many other considerable change

METHOD FOR THERMO-CHEMICAL PROCESSING OF WORKING SUBSTANCE FOR THERMO-LUMINESCENT DETECTOR BASED ON BERYLLIUM OXIDE CRYSTALS

FIELD: thermo-luminescent dosimetry of photon radiation of x-ray and gamma spectrums, and also electronic radiation, namely, methods for preparing working substances of thermo-luminescent detectors. SUBSTANCE: suggested method for thermo-chemical processing of working substance for thermo-luminescent detector based on beryllium oxide crystals includes placing BeO crystals in upper part and metallic beryllium in lower part of two-sectional molybdenum container and its following heating, ensuring thermal processing of crystals in restorative atmosphere of beryllium fumes under pressure. BeO crystals are activated by sodium ions in advance, and thermo-chemical processing is performed at temperature of 1920-1970°C and pressure of beryllium fumes 2,6?2,7 kPa during 2-3 hours with following cooling of container at 1,5-2°C/sec speed. EFFECT: creation of method for thermo-chemical processing of working substance for thermo-luminescent detector on basis of beryllium oxide crystals, reducing number of spikes of thermo-stimulated luminescence, simplifying reading mode, reducing reading time of dosimetric information and increasing sensitivity of thermo-luminescent detector. 2 dwg.Предложенное изобретение относится к области термолюминесцентной дозиметрии фотонного излучения рентгеновского и гамма-диапазонов, а также электронного излучения, а именно к способам приготовления рабочих веществ термолюминесцентных детекторов. Задачей изобретения является разработка способа термохимической обработки рабочего вещества для термолюминесцентного детектора на основе кристаллов оксида бериллия, уменьшающего число пиков термостимулированной люминесценции (ТСЛ), упрощающего режим считывания, снижающего время считывания дозиметрической информации и повышающего чувствительность ТЛД детектора. Предложенный способ термохимической обработки рабочего вещества для термолюминесцентного детектора на основе кристаллов оксида бериллия заключается в размещении кристаллов ВеО в верхней части и металлического бериллия в нижней части двухсекционного молибденового контейнера и последующем нагреве его, обеспечивающем термообработку кристаллов в восстановительной атмосфере паров бериллия под давлением. При этом кристаллы ВеО предварительно активируют ионами натрия, а термохимическую обработку ведут при температуре 1920-1970°С и давлении паров бериллия 2,6?2,7 кПа в течение 2-3 часов с последующим охлаждением контейнера со скоростью 1,5-2°С/с. 2 ил

О верификации измерений скорости поверхностных течений когерентным радаром СВЧ-диапазона с помощью дрифтеров

Introduction. Conventional contact measurements of hydrographic parameters frequently fail to provide the necessary accuracy of data in the field of water area monitoring. This problem can be solved using coherent radars enabling direct measurements of surface current velocities.Aim. To establish the accuracy of surface current velocities measured by a Doppler radar using drifter data.Materials and methods. In June 2022, coastal operational oceanography studies were conducted at the hydrophysical test site of the Institute of Oceanology of the Russian Academy of Sciences in the Black Sea near Gelendzhik. Measurements were carried out using a coherent X-band radar installed on the Ashamba research vessel simultaneously with drifter experiments using Lagrangian drifters of the near-surface layer with an underwater 0.5 m sail. Coordinates were transmitted via mobile communication. The drifter data on the current velocity and direction were used to verify radar measurements. Measurements were taken onboard of the research vessel at a low speed and different distances from the shore, near the drifters. The tracks of the vessel and drifters were recorded simultaneously. Processing of the radar data involved obtaining Doppler spectra of signals to estimate the dynamic processes on the sea surface, including the current velocity.Results. Radial components of the near-surface current velocity were calculated. Then, the current velocity values obtained based on the drifter and radar data were compared.Conclusion. The present work makes a contribution to the advancement of methods for measuring surface currents from the board of a moving ship by Doppler radars. The obtained results confirm the suitability of the radar hardware and software and signal processing algorithms for measuring currents. The radar measurement data were found agree well with drifter data in the velocity range from 15 cm/s.Введение. Традиционные контактные средства измерений гидрографических параметров зачастую не обеспечивают необходимую оперативность получаемых данных для решения задач мониторинга акваторий. Перспективным направлением является применение когерентных радаров, позволяющих непосредственно измерять скорости поверхностных течений.Цель работы. Оценка достоверности результатов измерений приповерхностной скорости течения доплеровским радаром сравнением с данными дрифтеров.Материалы и методы. В июне 2022 г. был проведен эксперимент по прибрежной оперативной океанографии в Черном море на акватории гидрофизического полигона "Геленджик" Южного отделения Института океанологии РАН с использованием доплеровского радара. Скорость течения измерялась когерентизированным навигационным радиолокатором сантиметрового диапазона с цифровой обработкой, установленным на научноисследовательском судне "Ашамба", одновременно с дрифтерными экспериментами с использованием лагранжевых дрифтеров приповерхностного слоя с подводным парусом высотой 0.5 м, с передачей координат по мобильной связи. Данные дрифтеров о скорости и направлении течения использовались для верификации радарных измерений. Измерения проводились с борта научно-исследовательского судна на малом ходу на различном расстоянии от берега, вблизи дрифтеров. В процессе измерений осуществлялась запись треков судна и дрифтеров. Обработка данных радиолокатора основана на исследовании спектральных характеристик отраженного сигнала, позволяющих оценивать динамические процессы на морской поверхности.Результаты. По результатам обработки доплеровских спектров были получены радиальные составляющие скорости приповерхностных течений, далее было выполнено сопоставление скорости течений по данным дрифтеров и данным радиолокации.Заключение. Настоящая работа является определенным шагом в усовершенствовании методов измерений поверхностных течений с борта движущегося судна доплеровским радаром. Результаты верификации подтверждают пригодность аппаратно-программной части радара и алгоритмов обработки сигнала для измерения течений. Данные радиолокационных измерений хорошо согласуются с данными дрифтеров в диапазоне скоростей от 15 см/с

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

Search for stop and higgsino production using diphoton Higgs boson decays

Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass

Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe