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Bulk crack-free Fe-Cr-Ni-Mo-Si-B alloy (with high hardness of 54.5 HRC) was fabricated via laser metal deposition (LMD). The solid-state phase transformation (PT) volume effect, transformation-induced plasticity (TRIP), and the influences of PT strain on the tensile properties of Fe-Cr-Ni-Mo-Si-B alloy were investigated, and the problem of how to release thermal contraction through PT strain in the LMD process was discussed. The results show that the volume strain of the martensite PT of Fe-Cr-Ni-Mo-Si-B alloy was equivalent to the thermal contraction strain caused by a temperature decrease of about 370 °C for the austenite of this alloy, and the PT volume expansion effect increased with a decrease in transformation temperature. In the LMD process, the Magee effect had an obvious contribution on the TRIP, but the decrease of tensile stress during the actual PT process must be considered. Under constant load conditions close to the yield strength, the strain of TRIP should be an order of magnitude higher than that of the transition volume effect. In situ neutron diffraction demonstrated that the martensite starting point (Ms) of PT can be significantly increased by stress and plastic. The highest martensite starting temperature of strain induced PT (Md) is about 360 °C higher than that of PT without external stress. PT strain can endow the materials, which are completely brittle at room temperature, with an elongation up to 34% in the tensile process. Thermal contraction strain the LMD process can be counteracted by PT strain, thus achieving the crack-free formation of high-hardness materials.

A carbide-free bainite steel of 0.29C–2.50Si-1.50Mn-1.0Mo-0.97Cr (wt.%) with no voids and cracks was fabricated via laser powder deposition (LPD). Different post-treatment plans were conducted and then microstructures and properties of the steel were studied through optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD), transmission electron microscopy (TEM), hardness meter and tensile test machines. Obtained results show that the microstructure of the deposited specimen consisted of granular pearlite and retained austenite (RA). The yield strength, tensile strength and elongation were 662 ± 71 MPa, 1051 ± 65 MPa and 13.03 ± 1.33 %, respectively. After austempering at 578 K, the microstructure of the specimen changed to bainite ferrite (BF) and RA. Moreover, it was found that the yield strength and tensile strength significantly increased to 1156 ± 60 MPa and 1289 ± 110 MPa, respectively. However, it had poor strain hardening capacity and elongation remained unchanged. After hot rolling and austempering, the RA content of the specimen significantly increased and the strain hardening capacity improved. However, when the isothermal temperature was less than the Ms temperature (i.e. 553 K), the corresponding microstructure consisted of martensite, BF and 13.6 vol% of RA. In this case, the yield strength, tensile strength and elongation were 895 ± 74 MPa, 1157 ± 92 MPa and 14.59 ± 1.13 %, respectively, indicating slight improvement. Meanwhile, it was found that when the isothermal temperature exceeded Ms temperature, the mechanical properties improved significantly. The present study demonstrated that specimens with an isothermal temperature of 578 K had the best mechanical properties. In particular, the yield strength, tensile strength and elongation of the optimized alloy were 1177 ± 44 MPa, 1398 ± 57 MPa and 19.80 ± 0.79 %, respectively.

The aim of the study was to improve the lamellar structure and wear resistance of arc-sprayed coatings. FeNiCrAl arc-sprayed coatings were remelted by the tungsten inert gas welding method. The as-sprayed and remelted specimens were subjected to comparative structural phase composition examination using optical microscopy, scanning electron microscopy and X-ray diffraction. Additionally, the effect of the remelting treatment on the wear mechanism of the arc sprayed coatings was also studied. It was found from the experiments that the tungsten inert gas surface process has the potential to form pore- and crack-free coatings. Further investigations showed that the dominant mechanism of wear for the as-sprayed coatings was oxide delamination and for the tungsten inert gas remelted coatings was cutting and ploughing Усовершенствованы пластинчатая структура и износостойкость покрытий, полученных электродуговой металлизацией. С помощью дуговой сварки вольфрамовым электродом в среде инертного газа проведена переплавка покрытий на основе FeNiCrAl, полученных электро-дуговой металлизацией. С использованием методов оптической микроскопии, растровой электронной микроскопии и дифракции рентгеновских лучей осуществлено сравнительное исследование структуры и фазового состава напыленных и переплавленных покрытий. Изучено влияние обработки путем переплавки на механизм износа покрытий, полученных электро-дуговой металлизацией. Установлено, что реализация дуговой сварки вольфрамовым электродом в среде инертного газа позволяет разрабатывать покрытия без пор и трещин. Даль- нейшие исследования показали, что основной признак износа покрытий, полученных электро-дуговой металлизацией, – расщепление оксида, в то время как покрытий, переплавленных с помощью дуговой сварки вольфрамовым электродом в среде инертного газа, – резание и пропахивание. Удосконалено пластинчасту структуру та зносостійкість покриттів, отриманих електро-дуговою металізацією. За допомогою дугового зварювання вольфрамовим електро-дом у середовищі інертного газу проведено переплавку покриттів на основі FeNiCrAl, отриманих електродуговою металізацією. Із використанням методів оптичної мікроскопії, растрової електронної мікроскопії та дифракції рентгенівських променів проведено порівняльне дослідження структури і фазового складу напилених і переплавлених покриттів. Вивчено вплив обробки шляхом переплавки на механізм зношення покриттів, отриманих електродуговою металізацією. Установлено, що реалізація дугового зварювання вольфрамовим електродом у середовищі інертного газу дозволяє розробляти покриття без пор і тріщин. Подальші дослідження показали, що основними ознаками зношення покриттів, отриманих електродуговою металізацією, є розщеплення оксиду, в той час як покриттів, переплавлених за допомогою дугового зварювання вольфрамовим електродом у середовищі інертного газу, – різання і проорювання

This study aims at evaluating the effect of the TIG (Tungsten Inert Gas) remelting treatment of self-fluxing FeNiCrAlBRE alloy coatings, formed by means of high velocity arc spraying on steel surfaces. The treated and untreated samples were subjected to comparative structural examination using scanning electron microscopes. For quantitative investigation of porosity, a computer image analyser was used. Additionally, the wear resistance and wear volume loss of the worn tracks before and after the remelting process were contrastively evaluated in details. After the sprayed coatings were treated by TIG remelting in a proper conditions, the microstructure examination of the remelted coatings showed that a change of the microstructure from lamellar to cellular structure. Also, the results show that the remelting process decrease the coating defects and make the coating more wearable.

Summary The existence of the random noise has a negative impact on the seismic prospecting records processing. An important step for improving attenuation methods is to scientifically characterize the properties of the seismic random noise. The modeling research is meaningful for cognizing the nature of the seismic random noise. In this study, we present a preliminary research of the parametric modeling for the seismic prospecting random noise. According the actual conditions of the seismic prospecting, a modeling algorithm based on fraction Brownian motion is proposed. By comparing the spectral properties between the noise data and its simulated results, the optimum parameter can be determined. We check the performance of the modeling algorithm by comparing the simulated record to the real noise data in terms of power spectral density and statistical moments. The experiments prove the appropriateness of our modeling algorithm.

The existence of the random noise is one of the main obstacles for getting higher-accuracy seismic records. The investigation of the seismic random noise properties is the pathway for improving the performance of noise attenuation algorithms. Here, we use the statistical testing methods to investigate the linearity of land-seismic-prospecting random noise, whereas the linearity, to some extent, can reflect the complexity of the generating process of the noise. The results show that the noise cannot be considered as a linear stochastic process. By analyzing the behaviors of the dataset, we obtain that the non-linear noise always have more energy in high frequency bands, and the energy distributions of the non-linear noise are disordered in high frequencies. Thus, the linearity of the random noise should be improved by attenuating the energy in high frequencies. We use an experiment to prove the correctness of our results. Based on the generating mechanism of the random noise, we also give a reasonable explanation for the results of our study. The findings have implications for future noise reduction and signal detection algorithms.

China Spallation Neutron Source (CSNS) is the first high-performance pulsed neutron source in China, which will meet the increasing fundamental research and technique applications demands domestically and overseas. A new distributed data processing and analysis environment has been developed, which has generic functionalities for neutron scattering experiments. The environment consists of three parts, an object-oriented data processing framework adopting a data centered architecture, a communication and data caching system based on the C/S paradigm, and data analysis and visualization software providing the 2D/3D experimental data display. This environment will be widely applied in CSNS for live data processing., 13 pages, 8 figures

We study the decays of the J / ψ and ψ ′ mesons to π + π − π 0 using data samples at both resonances collected with the BES III detector in 2009. We measure the corresponding branching fractions with unprecedented precision and provide mass spectra and Dalitz plots. The branching fraction for J / ψ → π + π − π 0 is determined to be ( 2.137 ± 0.004 ( stat. ) − 0.056 + 0.058 ( syst. ) − 0.026 + 0.027 ( norm. ) ) × 10 − 2 , and the branching fraction for ψ ′ → π + π − π 0 is measured as ( 2.14 ± 0.03 ( stat. ) − 0.07 + 0.08 ( syst. ) − 0.08 + 0.09 ( norm. ) ) × 10 − 4 . The J / ψ decay is found to be dominated by an intermediate ρ ( 770 ) state, whereas the ψ ′ decay is dominated by di-pion masses around 2.2 GeV/ c 2 , leading to strikingly different Dalitz distributions.

A GEANT4-based full Monte-Carlo model is developed to simulate the performance of the endcap time-of-flight (TOF) system of the BESIII detector with high accuracy and sufficient speed. Experimental data of e(+)e(-) collisions collected at BESIII are used to test this model, which can also be applied to other cases for precisely simulating optical photons propagating in scintillators with an irregular geometry. (C) 2010 Elsevier B.V. All rights reserved.

This paper will discuss the design and construction of BESIII, which is designed to study physics in the tau-charm energy region utilizing the new high luminosity BEPCII double ring e+e- collider. The expected performance will be given based on Monte Carlo simulations and results of cosmic ray and beam tests. In BESIII, tracking and momentum measurements for charged particles are made by a cylindrical multilayer drift chamber in a 1 T superconducting solenoid. Charged particles are identified with a time-of-flight system based on plastic scintillators in conjunction with dE/dx (energy loss per unit pathlength) measurements in the drift chamber. Energies of electromagnetic showers are measured by a CsI(Tl) crystal calorimeter located inside the solenoid magnet. Muons are identified by arrays of resistive plate chambers in the steel magnetic flux return. The level 1 trigger system, Data Acquisition system and the event filter system based on networked computers will also be described., 57 pages, 75 figures

The development of unmanned surface vehicles (USVs) for reconnaissance or other littoral missions is attracting increasing attention. In order to increase the sustainability of USVs, a new hybrid driving system powered by solar energy and wind energy is designed for the proposed USV. The developed USV is based on a catamarans prototype boat, and is equipped with a wing sail. In addition, the superficial of the USV is covered with PV panels for providing sustainable energy generation. The batteries based storage system is used for storing extra electricity as well as providing electricity for the control system and electrical system. To achieve tasks independently and intelligently, the USV is integrated with an automatic control system. The USV is discussed in detail, and some testing results are presented to validate its feasibility.

Wear-resistant FeNiCrAlBRE/Ni95Al composite coatings were deposited on carbon steel plate by high velocity arc spraying. Adhesive strength of the composite coating was improved by spraying Ni95Al cored wires as transition layer between working coating and substrate. Scanning electron microscopy and Vickers hardness testing were used to evaluate coatings structure and mechanical properties. For quantitative investigation of porosity, a computer image analyzer was used. The forming, the wear resistance and its mechanism of the coatings were studied. The results show that coating has relatively high average hardness about 550 HV0.1 and adhesive strength is 47 MPa. The worn surface characterized shallow grooves and few of debris on the coating manifested that the coating has better wear resistance under dry sliding conditions.

Spinel structure of (Mg, La) substituted spinel Ni-Zn ferrite has been synthesized by sol–gel auto combustion method. The ferrite exhibits a single-spinel structure. The ferrite is studied as a microwave absorbing material. The microwave measurements are carried out by a vector network analyzer. The reflection loss of the ferrite is calculated as a single-layer absorber. The results indicate that the ferrite annealed at 850°C has great potential for application in electromagnetic wave attenuation.