Experimental verification of an APF linac for a proton therapy facility

Alternating phase focusing (APF) is known as a beam focusing method; it was applied to an interdigital H-mode structure and successfully accelerated high current proton beams up to the desired energy for a medical synchrotron injector. A high-current APF linac was achieved by the optimal design of the cavity and the drift tubes themselves, as well as drift tube arrangement based on the co-iteration of a precise electromagnetic field and space charge beam dynamics.A proton injector for a medical accelerator complex was fabricated with the newly developed APF linac. The injector consists of an electron cyclotron resonance ion source, a radio-frequency quadrupole linac and the APF linac. The experimental results showed that over 10 mA proton beams were accelerated up to 7.4 MeV.     

Analysis of interlaboratory comparisons affected by correlations of the reference standards and drift of the travelling standards

The paper describes a method for analysing interlaboratory comparison results among accredited laboratories. Interlaboratory comparisons are used in order to achieve or to maintain the accreditation following the ISO/IEC 17025 standard. The used approach permits an evaluation of the reference value and of the degree of equivalence in the cases in which the laboratories participating are mutually dependent and the travelling standards are not stable during the comparison. This approach, as an example, was applied to analyse the SIT (Servizio di Taratura in Italia) interlaboratory comparisons carried out for the pressure quantity in the range from 10 MPa to 100 MPa (gage mode and liquid medium) and in the range from 0.15 MPa to 7 MPa (gage mode and gas medium).     

基于FPGA的数字激光自动功率控制系统设计

半导体激光器的自动功率控制是解决激光器阈值漂移的重要手段,本文设计了一个基于FPGA的数字激光自动功率控制系统,该控制系统主要由光电检测、A/D转换、SOC控制、APC判定、PWM反馈输出及低通滤波几个部分组成。该自动功率控制系统使用硬件资源少,根据不同的设计要求,通过增加PWM模块和简单的模拟器件或者改变控制寄存器的设置,就可以实现多级激光功率和多个激光器的控制,可以大大缩短设计周期。     

一种远程应用级数据库容灾系统的设计与实现

该文提出并实现了一种远程应用级数据库容灾系统。该系统支持多种灾难备份及恢复策略,可实时地将本地数据库的数据及相关操作同步到远程备用数据库中,保证两地数据的一致性。当本地主数据库发生故障时,可迅速切换数据库服务到远程备用数据库。     

进路式采矿法在我国的应用现状

进路式采矿法在我国的黄金和有色金属矿山得到了较为广泛的应用 ,该方法具有采场布置灵活、回采率高、损失贫化率小、可开采矿岩不稳定的矿体等优点。本文介绍了各种技术方案的应用实例及取得的技术经济指标和存在的问题 ,提出了加强技术管理、研制新型配套设备、寻求新的充填材料是今后的改进方向。     

火区下矿石回采方法试验研究

介绍一种火区下采矿的方法。根据易燃矿石的性质,选配出适用的阻化剂──石灰,将其制成阻化液泵入火区灭火阵温,然后用铺设钢筋混凝土假底的下向进路式水砂充填法采矿。这种方法安全、经济,有重大的推广价值。     

用SAR原始数据对雷达脉冲信号失真的校正

该文提出了一种对雷达发射脉冲进行相位估计的算法。该算法利用Chirp Scaling原理对SAR信号进行距离迁移校正,但仅在方位向波束锐化,然后利用自聚焦的方法(Map Drift,PGA),在距离向进行自聚焦处理,提取距离向的相位误差信息。文中分析了影响相位估计精度的各种因素,并在算法中加入了迭代补偿方法,仿真结果验证了算法的正确性。     

Investigation of crystal structure,electrical and dielectric response of Zr4+ -Co2+ substituted Ba–Sr–Ni Y-type hexagonal ferrites synthesized by sol-gel route

A series of (Zr–Co) substituted Y-type polycrystalline hexaferrite with composition SrBaNi₂(ZrCo)_xFe_12-2xO₂₂ (x = 0.0, 0.25, 0.50, 0.75, 1.0) were fabricated by sol-gel auto combustion method. Pure Y-type single phase formation was achieved at a relatively lower temperature of 1150 °C for 5:30 h. The fabricated nano ferrites were examined by X-ray powder diffraction to confirm the pure single-phase formation of Y-type hexaferrites. An increase in lattice parameters (a& c) was observed by adding Zr⁴⁺-Co²⁺ metal cations. Crystallite size (D) measured in the 48-19 nm range. FTIR spectra clarified iron-oxygen vibrational bands at 417-487 cm^?1, which approved the Y-type hexaferrites formation. DC electrical resistivity has an opposite trend at high and low temperatures with increasing Zr⁴⁺-Co²⁺ content (x). DC electrical resistivity values depend on grain size; they have an inverse relation. Activation energy, drift mobility, and Curie temperature were also determined. Conduction is due to the hopping of electrons below the Curie temperature, and polarons are responsible for hopping above the Curie temperature. Activation energy varies from 0.39 to 0.10 eV with the substitution of Zr⁴⁺-Co²⁺ ions. A wide frequency range of dielectric characteristics (1 MHz–6GHz) was observed, and these parameters revealed a considerable fluctuation with the substitution of Zr⁴⁺–Co²⁺ ions. Dielectric constant, dielectric loss and ac conductivity of nano ferrites materials increased with frequency and Zr⁴⁺-Co²⁺ content (x). Complex impedance spectroscopy formalism using the Cole-Cole plots indicated that most dielectric responses arise from grain boundary contributions.     

高精度半导体激光二极管温度控制系统

本文使用通用器件，基于比例－ 积分－ 微分（ Ｐ Ｉ Ｄ） 控制技术精心设计了高精度温度控制系统，系统中的 Ｐ Ｉ Ｄ 调节器和相关的辅助电路以及恒温阱，保证了系统的高精度、高稳定性以及实用性。这些辅助电路包括精密电压源、工作温度点设定电路、积分饱和释放电路和温度调节状态显示电路等。系统设计精度为±１ ｍ Ｋ。实验显示，在长时间（ 大于８ ｈ） 内，系统温漂小于±１０ｍ Ｋ。最后分析了实验误差的来源和改进方法