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INFLUENCE OF ORDINARY accelerators ON HYDRATION OF BELITE CEMENT

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Journal of Wuhan University of Technology(Materials Science) 1999年第4期14卷 33-39页

作者： GUO Suihua FENG Peizhi ZENG Yimin LUO ShiyongChina Building Materials Academy Wuhan University of TechnologyUniversity of Technology and Science Beijing China Building Materials Academy China Cement and Concrete Sci. Institute China Building Materilas Academy Beijing 100024 China Wuhan University of Technology China Univ. of Technol. and Sci. Beijing China

The study revealed that ordinary acceler- ators for portlandcement also improves early strength of Belite cement remarkably, butone serious defect exists Which lead to a high strength reduction atthe age of 28 days. The paper analyzes the action mechanism ofordinary accelerators on Belite cement. It shows that theseaccelerators can not accelerate the hydration of β-C_2S directly.

关键词： Belite cement hydration accelerators

Induced radioactivity at particle accelerators:a short review

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Radiation Detection Technology and Methods 2021年第4期5卷 481-492页

作者： Shakhboz Khasanov Bo Yang Youwu Su Akmal Safarov Yao Yang Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Samarkand State University SamarkandUzbekistan140104 Institute of Advanced Science Facilities Shenzhen 518107China

Purpose The induced radioactivity in accelerator components and decay characteristics of radioactive nuclei contained therein is critical for radiation safety of occupational workers as well as for the maintenance,repair,and decommissioning activities.The topic of induced radioactivity is widely reported and extensively explored in the literature by many researchers up to now.This mini-review would demonstrate the current state of the knowledge on induced radioactivity at particle accelerators.Methods In this article,the concepts of activation-related studies and radionuclide generation in accelerator environments are reviewed.In addition,some studies on accelerator-induced radioactivity by Monte Carlo and experimental measurement methods are briefly described.Results and conclusions The possible radiation protection problems caused by particle accelerator-induced radioactivity are briefly reviewed and analyzed.The produced radionuclides depend on the beam parameters such as particle type,energy,irradiation period,cooling time,and irradiated material.The Monte Carlo simulation method offers comparable advantages over empirical analysis method.A review of major studies in the field of induced radioactivity of particle accelerators confirmed that the extremely strong induced radioactivity generated at hot spots of accelerators means new challenges to radiation safety and deserves further investigation and discussion.

关键词： accelerators Radioactivity Monte Carlo Radiation protection

Leaching of metals on stabilization of metal sludge using cement based materials

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Journal of Environmental Sciences 2005年第1期17卷 115-118页

作者： CarmalinSophiaA K.Swaminathan NationalEnvironmentalEngineeringResearchInstitute ChennaiZonalLaboratoryCSIRCampusTaramaniChennai-600113India

Toxicity characteristic leaching procedure(TCLP) of zinc plating sludge was carried out to assess the leaching potential of the sludge and the leachates were analyzed for heavy metals. The concentration of zinc, chromium, and lead in the leachate were 371 5 mg/L, 1 95 mg/L and 1 99 mg/L respectively Solidification of zinc sludge was carried out using four different binder systems consisting of cement mortar, fly ash, clay and lime and cured for 28 d. The ratio of sludge added varied from 60% to 80% by volume. The solidified products were tested for metal fixing efficiency and physical strength. It was observed that the volume of sludge added that resulted in maximum metal stabilization was 60% for all the combinations, above which the metal fixation efficiency decreased resulting in high values of zinc in the leachate. Addition of 5% sodium silicate enhanced the chemical fixation of metals in all the binder systems. Among the four fixing agents studied, mixture of fly ash: lime, and cement mortar: lime stabilized zinc and other metals in the sludge effectively than other combinations. Addition of lime increased the stabilization of zinc whereas cement mortar increased the strength of the solidified product.

关键词： solidification stabilization leaching binders accelerators

Theoretical Design of a 104MHz Ladder Type IH-RFQ Accelerator

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Chinese Physics Letters 2010年第11期27卷 47-50页

作者：聂元存陆元荣陈佳洱颜学庆高淑丽朱昆刘克新郭之虞 State Key Laboratory of Nuclear Physics and Technology Institute of Heavy Ion Physics Peking University Beijing 100871

Beam dynamics and rf designs of a 104 MHz ladder type IH-RFQ （L-IH-RFQ） accelerator are finished at Peking University for the acceleration of 14C＋ from 40 keV to 500 keV. As a specific feature, the output beam energy spread is as low as 0.6% achieved with the internal discrete bunching method, which makes potential applications of RFQ feasible, such as accelerator mass spectrometry and ion implantation. Tolerances of the beam dynamics design are studied by means of changing the input beam parameters, and the results are quite satisfying. On the other hand, the L-IH-RFQ structure is employed, taking advantage of its mechanical stability and the absence of inter-electrode voltage asymmetry. Radio-frequency properties are studied and optimized for reducing power loss with Microwave Studio （MWS）. Tuning of the field flatness and frequency is investigated in principle.

关键词： accelerators beams and electromagnetism Nuclear physics Instrumentation and measurement Particle physics and field theory

Assessment of Primordial Radionuclides in Pakistani Red Bricks and Associated Radiation Doses

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Chinese Physics Letters 2010年第3期27卷 343-346页

作者： K. Khan A. Jabbar P. Akhter M. Tufail H. M. Khan Health Physics Division PINSTECH P.O. Box 1482 Nilore Islamabad Pakistan Pakistan Institute of Engineering and Applied Sciences P.O. Nilore Islamabad Pakistan National Centre of Excellence in Physical Chemistry University of Peshawar Pakistan

Specific activity of primordial radionuclides and associated radiation hazards due to 40K, 226Ra, and 232Th have been measured in backed red brick samples, collected from five highly populated areas of the North West Frontier Province of Pakistan. For the detection, analysis and data acquisition, a high purity germanium detector was used. Associated external doses were calculated using a Monte Carlo neutron photon transport code. A theoretical model to determine the gamma dose rate at 1 m height from the floor, made of bricks, was employed for the calculation of mass attenuation coefficient and self-absorption in the floor for the gamma energies of these radionuclides and their progeny. Monte Carlo simulation shows that in this study the floor, having more than an effective thickness of 15 cm, contributes very little to the external gamma dose rate. The values of the external dose rate and annual effective dose are found to be much lower than the world average as well as from other countries of the world.

关键词： accelerators beams and electromagnetism Nuclear physics Instrumentation and measurement Environmental and Earth science Particle physics and field theory Astrophysics and astroparticles

An overview of design for CSNS/RCS and beam transport

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Science China(Physics,Mechanics & Astronomy) 2011年第S2期54卷 239-244页

作者： WANG Sheng AN YuWen FANG ShouXian HUANG Nan LIU WeiBin LIU YuDong QIN Qing QIU Jing WANG Na XU Gang XU ShouYan YU ChengHui Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China

The China Spallation Neutron Source (CSNS) is the first accelerator-based pulsed neutron source in China. Its accelerators are made up of an 80 MeV H- linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. RCS accumulates and accelerates protons to the design energy of 1.6 GeV, and extracts high energy beam to strike the target. The overview of RCS is presented, and the key problems of the physics design are discussed. The two beam transport lines, from linac to RCS and from RCS to the target, are also introduced.

关键词： CSNS high intensity accelerators rapid cycling synchrotron beam loss

Effect of Accelerant Additives in Concrete with Limestone Aggregate in Warm Weather

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Journal of Building Construction and Planning Research 2022年第4期10卷 140-154页

作者： Romel G. Solís Diego R. Hay Jesus Nicolás Zaragoza Department of Construction School of Engineering Autonomous University of Yucatan Mérida México

Additives are chemical compounds that are added to concrete during its manufacture to modify one or more of its properties. The first additive used in modern concrete was the accelerator, intended to shorten the time during which the material is not capable of supporting stress. Traditionally, accelerators have been made from calcium chloride, but today the trend is to use chloride-free additives to prevent reinforcing steel from corroding and thereby make constructions durable. The objective of this study was to evaluate the effects on the concrete of two types of accelerating admixture, using limestone aggregates, under warm sub-humid climate conditions. The applied methodology consisted of the measurement in the laboratory of some of the main properties of concrete in fresh and hardened states, in samples manufactured both with and without accelerators. The results showed that the accelerator without chloride was less effective than the one based on calcium chloride and that without doses of the accelerator, the effectiveness documented by the manufacturers was achieved.

关键词： Concrete Additives accelerators Limestone Aggregates Durability

GPU Accelerated Discontinuous Galerkin Methods for Shallow Water Equations

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Communications in Computational Physics 2015年第6期18卷 37-64页

作者： Rajesh Gandham David Medina Timothy Warburton Department of Computational and Applied Mathematics Rice University6100 Main StreetMS-134HoustonTX-77005USA

We discuss the development,verification,and performance of a GPU accelerated discontinuous Galerkin method for the solutions of two dimensional nonlinear shallow water equations.The shallow water equations are hyperbolic partial differential equations and are widely used in the simulation of tsunami wave propagations.Our algorithms are tailored to take advantage of the single instruction multiple data(SIMD)architecture of graphic processing units.The time integration is accelerated by local time stepping based on a multi-rate Adams-Bashforth scheme.A total variational bounded limiter is adopted for nonlinear stability of the numerical scheme.This limiter is coupled with a mass and momentum conserving positivity preserving limiter for the special treatment of a dry or partially wet element in the triangulation.Accuracy,robustness and performance are demonstrated with the aid of test cases.Furthermore,we developed a unified multi-threading model OCCA.The kernels expressed in OCCA model can be cross-compiled with multi-threading models OpenCL,CUDA,and OpenMP.We compare the performance of the OCCA kernels when cross-compiled with these models.

关键词： Shallow water equations discontinuous Galerkin positivity preserving slope limiting GPUs accelerators multi-threading

BEPC and Other Big accelerators

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Bulletin of the Chinese Academy of Sciences 2019年第4期33卷 221-225页

To understand the nature of"matter",scientists have to answer some very basic questions.For example,why there are so many"elementary particles"?Are they really indivisible building blocks of our cosmos?Is the cosmos following some unknown physical laws,which potentially subvert our current understanding of the whole world?How should we understand the"dark matter"in the cosmos?Could the four fundamental forces comply with any common physical law in the same framework?

关键词： Neutron accelerators world