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41.
旋转式伽玛刀的辐射剂量学 总被引:4,自引:0,他引:4
旋转式伽玛刀的辐射剂量学指标的物理测试在放射性医疗设备投放医院正式临床使用前是必不可少的,是对设备及其附件的设计、加工制造、安装以及电气控制系统等的全面综合性检定。用电离室作辐射剂量学的绝对测量,用胶片法进行相对测量,给出了测量结果并进行了讨论。 相似文献
42.
Chih-Chun Hsieh Tao-Chih Chang Dong-Yih Lin Ming-Che Chen Weite Wu 《Metals and Materials International》2007,13(5):411-416
The purpose of this study is to investigate the precipitation characteristics of σ phase in the fusion zone of stainless steel
welds at various welding passes during a tungsten are welding (GTAW) process. The morphology, quantity, and chemical composition
of the δ-ferrite and σ phase were analyzed using optical microscopy (OM), a ferritscope (FS), a X-ray diffractometer (XRD),
scanning electron microscopy (SEM), an electron probe micro-analyzer (EPMA), and a wavelength dispersive spectrometer (WDS),
respectively. Massive δ-ferrite was observed in the fusion zone of the first pass welds during welding of dissimilar stainless
steels. The σ phase precipitated at the inner δ-ferrite particles and decreased δ-ferrite content during the third pass welding.
The σ and δ phases can be stabilized by Si element, which promoted the phase transformation of σ→ϱ+λ2 in the fusion zone of the third pass welds. It was found that the σ phase was a Fe−Cr−Si intermetallic compound found in
the fusion zone of the third pass welds during multi-pass welding. 相似文献
43.
Mei Xuan Xu Wen Guang Liu Yun Lin Guan Zuo Peng Bi Kang De Yao 《Polymer International》1995,38(2):205-209
The phase behavior of a hybrid polymer network (HPN) composed of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] crosslinked with styrene and polyester–urethane crosslinked with methylene-bis-ortho-chloroaniline was examined. The correlation between phase separation and impact strength of the HPNs is discussed. The composition of HPNs has an effect on their properties. 相似文献
44.
Ivan Cimrák 《Archives of Computational Methods in Engineering》2007,15(3):277-309
The Landau-Lifshitz (LL)equation of micromagnetism governs rich variety of the evolution of magnetization patterns in ferromagnetic
media. This is due to the complexity of physical quantities appearing in the LL equation. This complexity causes also an interesting
mathematical properties of the LL equation: nonlocal character for some quantities,nonconvex side-constraints, strongly nonlinear
terms. These effects influence also the numerical approximations. In this work, recent developments on the approximation of
weak solutions, together with the overview of well-known methods for strong solutions,are addressed.
Author is supported by the Fund for Scientific Research - Flanders FWO (Belgium). 相似文献
45.
利用平板型热管纺丝装置对普通高速纺丝机进行技术改造,并一步法生产出充分结晶的PET纤维(FCY)。该纤维可直接用于织造,调节热管温度、热管安装位置可获得满足后道工序不同需要的FCY。 相似文献
46.
47.
The effects of nitric oxide (NO) annealing on conventional thermal oxides are reported in this letter. The oxide thickness increase, resulting from NO annealing, is found to be only a few angstroms (<0.5 nm) and independent on the initial oxide thickness. Furthermore, both the electrical and physical characteristics are improved. This technique is expected to achieve sub-5 nm high quality ultrathin dielectric films for the applications in EEPROM's and ULSI 相似文献
48.
Many video service sites headed by YouTube know what content requires copyright protection. However, they lack a copyright
protection system that automatically distinguishes whether uploaded videos contain legal or illegal content. Existing protection
techniques use content-based retrieval methods that compare the features of video. However, if the video encoding has changed
in resolution, bit-rate or codec, these techniques do not perform well. Thus, this paper proposes a novel video matching algorithm
even if the type of encoding has changed. We also suggest an intelligent copyright protection system using the proposed algorithm.
This can serve to automatically prevent the uploading of illegal content. The proposed method has represented the accuracy
of 97% with searching algorithm in video-matching experiments and 98.62% with automation algorithm in copyright-protection
experiments. Therefore, this system could form a core technology that identifies illegal content and automatically excludes
access to illegal content by many video service sites. 相似文献
49.
In this paper we have proposed a dynamic pricing scheme for the contributing peers in the Video on Demand (VoD) system. The
scheme provides an effective mechanism to maximize the profit through the residual resources of the contributing peers. A
utilization function is executed for each contributing peer to estimate the utility factor based on the parameters such as
initial setup cost, holding cost, chaining cost and salvage cost. In this paper, we urge an effective dynamic pricing algorithm
that efficiently utilizes a range of parameters with a varying degree of complexity. The key findings of the algorithm are
(i) each contributing peers are benefitted by the monetary based on its resource contributions to the VoD system and (ii)
a high degree of social optimum is established by proficiently aggregating the contributing peer’s resources with the overall
resources of the VoD system. We validate our claim by simulating the proposed dynamic pricing scheme with other standard pricing
schemes such as altruism, cost model and game theory perspective. The result of our dynamic pricing scheme shows the best
utility factor than other standard pricing schemes. 相似文献
50.