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991.
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环境放射化学研究中几个问题的讨论 总被引:1,自引:0,他引:1
本文从辐射环境保护和公众辐射防护的角度,讨论了放射性核素在环境中的迁移行为,放射性核素与环境介质的相互作用和放射性核素在环境中的形态等涉及到环境放射化学研究方向的问题,并讨论了它们之间相互依存的关系。 相似文献
994.
P. Bala Srinivasan C. V. Krishnakumar N. Krishnaraj 《Journal of Materials Engineering and Performance》2002,11(5):509-515
Salt bath nitrocarburizing is a well-known thermochemical diffusion process for enhancing the tribological and corrosion properties
of ferrous components. The current work describes the role of a compound layer developed during nitrocarburizing, both in
the ferritic and austenitic regimes of Fe-N-C system, on the sliding wear behavior of a medium carbon steel. The wear behavior
of the nitrocarburized steel discs was assessed by the pin-on-disc tests (ASTM G 99-99) under different normal loads running
against a hardened SAE52100 pin. It was observed that the compound layer on the surface not only controlled the wear rate
but also resisted the adhesive wear/transfer of material from pin to disc, aside from providing low-friction coefficients. 相似文献
995.
多民族区域移民安置工作的探索 总被引:1,自引:0,他引:1
新疆吉林台水电站水库移民的特点是,少数民族多,牧业人口多,人均补偿投资多。其移民安置工作中遵循“政府负责,投资包干,业主参与,综合监理”的方针,建章立制,牢固树立依法行政的思想,做到有章可循,严格管理;认真编制、审核、执行移民计划;认真核定移民补偿实物量,发放补偿证,充分尊重移民意愿,保障少数民族移民的合法权益;抓好移民安置单项工程的建设,加强行政领导,加强移民干部队伍的建设;从而基本做到了政府满意,移民和业主满意。 相似文献
996.
Calogero D. Presti Francesco Carrara Giuseppe Palmisano 《Analog Integrated Circuits and Signal Processing》2007,51(1):51-54
A variable-gain up-conversion mixer for 5-GHz WLAN applications is presented, whose input stage is based on a novel variable
gain transconductor. The proposed topology features reduced power consumption by exploiting dc current reuse for mixer biasing.
Moreover, a new low-consumption control circuit is introduced, which achieves a temperature-stable and linear-in-dB characteristic,
providing a 40-dB dynamic range within ±1 dB gain error. 相似文献
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Hopkinson bar techniques have played an important role in the study of high-rate deformation and fracture behavior of materials.
In the current work, a split Hopkinson pressure bar was developed for dynamic four-point bend fracture testing, referred to
as a “two-bar (incident and transmitted bars)/four-point” (2-bar/4-pt) bend test. To further understand some fundamental issues
regarding stress wave propagation in this 2-bar/4-pt bend testing system, dynamic fracture tests were performed in pulse-shaped
and unshaped pulse testing conditions. The effect of the pulse shaper on the incident pulse characteristics (rise time and
duration), specimen’s dynamic response (load and loading point displacement), crack initiation time and stress-state equilibrium
were investigated experimentally in the current work. The present results show that stress state equilibrium can be achieved
prior to fracture initiation in notched and precracked specimens. In the pulse-shaped bending test, the specimen is more likely
to attain stress-state equilibrium than in an unshaped incident pulse test. The crack initiation time was extended and the
time required for attaining stress equilibrium was reduced by pulse shaping due to the tailored incident pulse having a longer
rise time, which ensures that stress equilibrium is achieved prior to crack initiation.
This article is based on a presentation made in the symposium entitled “Dynamic Behavior of Materials,” which occurred during
the TMS Annual Meeting and Exhibition, February 25–March 1, 2007 in Orlando, Florida, under the auspices of The Minerals,
Metals and Materials Society, TMS Structural Materials Division, and TMS/ASM Mechanical Behavior of Materials Committee. 相似文献