制造执行系统的可重构模型及其J2EE实现

车间生产环境的变化对制造执行系统（MES）提出重构要求。首先从引起MES重构的源头出发,构建了MES重构模型,接着介绍了基于J2EE（Java 2 Platform Enterprise Edition）的典型的MES多层体系结构,在此基础上,研究了基于J2EE的MES的四类重构特性,最后得出基于J2EE的MES能够以清晰的逻辑体系实现企业应用中业务元素改变、业务处理逻辑改变、外围系统改变以及生产组织改变所引起的系统重构要求。这种重构特性使得基于J2EE的MES能够随生产环境变化与企业需求保持同步增长,是实现结构敏捷化MES的基础。     

一种小型化频率可重构微带天线的设计

提出一种新型的小型化频率可重构微带天线.天线由1个倒L形的微带馈线、5个长宽不等的矩形贴片及1个阶梯型的接地面构成,天线整体尺寸为30 mm× 35 mm×1.6 mm.通过控制开关的状态选择相应的辐射单元,可改变表面电流分布,获得不同的工作频段,实现各个状态间的切换.该天线的10个有效工作状态可以等效覆盖1.89～1.92 GHz、2.16～2.32 GHz、2.39～2.91GHz、3.30～3.69 GHz、5.05～5.85 GHz5个不同的频段,各个状态下天线具有良好的全向特性.该天线在WLAN、Wimax、ZigBee、Bluetooth等无线通信系统中具有一定的应用价值.     

WebFrame:一种多层次可扩展的Web应用服务器

网络软件平台已成为当今软件技术发展的主流趋势和竞争焦点,Web应用服务器是Web计算环境下产生的新型中间件,是网络软件平台的关键与核心,已逐步成为信息化基础软件设施之一。该文重点介绍自主研制的WebFrame应用服务器的设计方法和思路,并分析了WebFrame的关键实现技术,给出了相应的解决办法,针对目前主流Web应用服务器存在的开放性和灵活性低等不足之处,WebFrame的设计遵循一种开放工程的方法,采用基于微内核的多层次可扩展模型,使得WebFrame具备在其生命周期内支持不同级别定制和可重配置的能力,满足不断变化的QoS需求,对比测试数据表明WebFrame具有较好性能。     

A participatory systems design methodology for changeable manufacturing systems

The ability to adapt to changes in products, processes and technologies is a key competitive factor. Changeable manufacturing paradigms have emerged to address this need, but the industrial implementation remains challenging. In this paper, a participatory design methodology for changeable manufacturing systems is proposed, including requirements specification, selection of appropriate manufacturing paradigm and suitable physical and logical enablers. The methodology supports companies in determining the potential for and mechanisms of transitioning towards changeable manufacturing systems, based on knowledge of products, production, technologies and facilities. The developed methodology is applicable to both new and existing manufacturing systems. It is demonstrated in two industrial cases which highlight its applicability and differences in the appropriate recommended manufacturing systems transition towards changeability as a result of differences in manufacturing characteristics, change requirements and enablers.     

Key technologies on microwave photonic filter

Microwave photonic filter (MPF) as one of the key devices in the radio-on-fiber (ROF) system has attracted much interest recently.Some key technologies of MPF including the coherence,quality factor (Q) and reconfigurability are introduced.The difference between the incoherent and coherent MPF (ICMPF and CMPF) is given,and the methods to realize an ICMPF are also introduced.Higher Q factor MPF can be developed with more taps,and it is proved by simulation.Then the methods of finite and infinite impulse response MPF (FIRMPF and IIRMPF) are both given.At last,the reconfigurability is verified by four kinds of window functions.     

基于认知的重配置无线网络技术

端到端重配置技术旨在解决异构无线网络融合和无线资源的最优化利用,随着重配置技术研究的发展和认知理论研究的不断深入,使得未来具有认知能力的重配置无线网络的实现成为可能。目前,对端到端重配置技术的研究包括重配置无线网络体系结构及实现向重配置无线网络的演进过程中的关键技术。     

Novel planar reconfigurable circularly polarized complementary antenna for unidirectional end‐fire radiation

In this article, a novel planar reconfigurable circular polarization (CP) complementary antenna for unidirectional end‐fire radiation is proposed. Its radiator is the combination of a shorted quarter wavelength patch and an electric dipole, which provide the vertical and horizontal polarizations, respectively. By adding a 90° phase delay line, the proposed antenna radiates CP electromagnetic waves in the unidirectional end‐fire direction. Four p‐i‐n diodes are also inserted at joints of the electric dipole and the phase delay lines, and two orthogonal CP states, left‐hand (LH) and right‐hand (RH) CPs, can be switched. In order to reduce the number of DC bias lines, electric dipole arms on both sides of the substrate are connected by metal via‐holes, which simplifies the DC bias lines. The proposed antenna at 2.45 GHz is designed and fabricated. Its measured impedance bandwidth with |S₁₁| < ?10 dB and 3‐dB axial ratio bandwidth are 2.1% and 10.7%, respectively. Additionally, its maximum half power beamwidth in xoz plane is 196°. Reasonable agreement between the measured and simulated results validates the polarization reconfigurability of the proposed antenna.     

Analysis and design of sea‐water monopole Yagi‐Uda antenna with pattern reconfigurability

In this article, a theoretical study of sea‐water monopole Yagi‐Uda antenna is presented. Unlike the conventional metal one, sea‐water monopole is here treated as imperfect conductor. Based on this precondition, a methodology for analyzing sea‐water monopole Yagi‐Uda antenna is proposed by employing the 3‐term theory and voltage‐current relation. As such, both its input impedance and radiation pattern can be theoretically predicted. Commercial software packages ANSYS HFSS and CST Microwave Studio are used to verify the proposed methodology. Finally, a prototype is designed, fabricated, and tested. Due to the liquidity of sea water, the parasitic element can work as a director or reflector by altering its height to achieve pattern reconfigurability. Measured results show reasonably good agreement with the simulated and theoretical ones.     

Multi-segment MPA with T-feed for multi-band wireless communication

The propagation constants for electrostatic waves in warm plasmas with random electron density are developed. It has been found that for a collisionless plasma attenuation exists. Although the attenuation coefficient depends on the statistical condition of the plasma at all frequencies, the phase constant is relatively unaffected by randomness at frequencies far greater than the mean plasma frequency. Finally, the group velocity of the wave changes sign in the frequency range close to the mean plasma frequency.     

低复杂度可配置变带宽滤波器组的设计

提出了一种低复杂度可配置变带宽滤波器组的设计方法,该方法基于快速滤波器组结构,并利用变带宽滤波器方法重新设计第0级原型滤波器而实现。该设计方法弥补了其他设计方案中带宽变化因子为整数的不足,同时在一定带宽的条件下,能够连续改变各子滤波器组通道的中心频率和在中心频率不变的条件下,能够连续可调对应的带宽。由于各级原型滤波器的系数具有稀疏特性,因而系统具有较低的实现复杂度,仿真结果表明,其所需乘法器的数量大约是其他方法的48.96%,可应用于如多标准无线接收机等变带宽场合中,完成频谱感知与数字信道化等功能。