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大多数8位MCU的嵌入式设备通过TCP/IPv4协议接入互联网,致使原本资源匮乏的IPv4地址空间更加紧张.提出了一种基于操作系统无关性的IPv6协议栈的设计方案,对IPv6、ICMPv6、ND协议进行了裁减,并进行了相关测试.结果表明,通过该协议栈将嵌入式设备接入Internet的方法,使得IPv6协议在嵌入式低端应用领域的普及成为可能. 相似文献
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叙述了在网络化DNC系统中引入嵌入式系统方案的必要性;在试验验证的基础上,提出了一套基于嵌入式系统的设计方法,以解决在网络化DNC系统构建过程中存在的现场数控设备多样性信息化特征之间互不兼容的问题。 相似文献
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针对可信计算平台信任链技术的实现,在可信与安全相关性研究基础上,总结了信任链技术中存在的几个值得探讨的问题,对可信与安全的关系、认证链和信任链的区别以及组件划分的粒度等问题进行了分析。提出了一种细粒度模糊信任链模型,对组件划分原则、组件、系统的安全度量方法和信任转移理论进行了深入研究。为可信计算信任问题的研究提供了一个可行的方案,对实际系统可信性和安全性研究具有参考意义。 相似文献
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一种用于可靠性自动化分析的故障系统描述模型 总被引:3,自引:0,他引:3
为了对系统的可靠性进行自动化分析, 本文在两个方面发展了进行故障系统描述的故障传递表模型: (1)对故障传递表的格式进行了较大改进; (2)提出了能流故障类, 以它为故障传递表描述的补充。采用这种改进的模型可方便地对系统进行多模态及复杂的故障关联描述。将模型应用于航空发动机液压机械控制系统的描述, 并自动建造故障树, 取得了较好的效果。 相似文献
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面向应用的嵌入式操作系统 总被引:4,自引:0,他引:4
讨论了经典的实时操作系统RTOS在嵌入式DSP和嵌入式Internet应用中的不适应性 ,提出了具有可伸缩性、可剪载性、具有强大主机开发支持能力以及面向应用特点的嵌入式实时操作系统的思想 ,并介绍了两种实际产品的特点和使用情况。 相似文献
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随着嵌入式系统的不断发展,BOOTLOADER程序开发和移植工作的复杂度越来越高,严重影响了嵌入式系统的开发进度.通过对BOOTLOADER程序引导过程的深入分析,从功能实现、运行过程和代码结构3方面展开研究,提出了一种通用BOOTLOADER架构,并在PowerPC平台上完成了架构的实现,验证了其正确性和易用性,能够有效地提高BOOTLOADER程序的开发和移植效率,进而缩短整个嵌入式系统的开发周期,对BOOTLOADER程序的开发和移植工作具有指导性意义. 相似文献
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Multi-agent cooperation problems are becoming more and more attractive in both civilian and military applications. In multi-agent cooperation problems, different network topologies will decide different manners of cooperation between agents. A centralized system will directly control the operation of each agent with information flow from a single centre, while in a distributed system, agents operate separately under certain communication protocols. In this paper, a systematic distributed optimization approach will be established based on a learning game algorithm.The convergence of the algorithm will be proven under the game theory framework. Two typical consensus problems will be analyzed with the proposed algorithm. The contributions of this work are threefold. First, the designed algorithm inherits the properties in learning game theory for problem simplification and proof of convergence. Second, the behaviour of learning endows the algorithm with robustness and autonomy. Third, with the proposed algorithm, the consensus problems will be analyzed from a novel perspective. 相似文献
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在基于微惯性器件的行人导航系统中,陀螺仪和加速度计的偏移是降低系统定位精度的重要因素。传统的标定方法大多在实验室中进行,后续导航解算都是基于标定后的固定模型,然而MEMS器件长时间工作后,标定模型参数发生变化会导致系统导航性能下降。通过分析行人导航系统及MEMS器件的特点,提出了一种基于误差模型的MEMS器件参数在线修正方法。根据行人行走的特点,检测并区分行走过程中的可修正区间与不修正区间。在可修正区间基于逆向解算算法实现了对陀螺仪和加速度计零偏的在线修正,并提出了主航向反馈修正算法,提高了行人导航系统长时间导航性能。实验结果表明,40m行走实验中,系统定位精度提升了9.07%;300m行走实验中,系统定位精度提升了13.14%。 相似文献
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Numerical simulation of aerodynamic interaction for a tilt rotor aircraft in helicopter mode 总被引:1,自引:1,他引:0
A rotor CFD solver is developed for simulating the aerodynamic interaction phenomenon among rotor, wing and fuselage of a tilt rotor aircraft in its helicopter mode. The unsteady Navier–Stokes equations are discretized in inertial frame and embedded grid system is adopted for describing the relative motion among blades and nacelle/wing/fuselage. A combination of multi-layer embedded grid and ‘‘extended hole fringe" technique is complemented in original grid system to tackle grid assembly difficulties arising from the narrow space among different aerodynamic components, and to improve the interpolation precision by decreasing the cell volume discrepancy among different grid blocks. An overall donor cell searching and automatic hole cutting technique is used for grid assembly, and the solution processes are speeded up by introduction of Open MP parallel method. Based on this solver, flow fields and aerodynamics of a tilt rotor aircraft in hover are simulated with several rotor collective angles, and the corresponding states of an isolated rotor and rotor/wing/fuselage model are also computed to obtain reference solution.Aerodynamic interference influences among the rotor and wing/fuselage/nacelle are analyzed,and some meaningful conclusions are drawn. 相似文献
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Lingfeng Wang 《Aerospace and Electronic Systems Magazine, IEEE》2008,23(1):28-34
The software complexity is continuously increasing and the competition in the software market is becoming more intensive than ever. Therefore, it is crucial to improve the software quality, and meanwhile, minimize software development cost, and reduce software delivery time in order to gain competitive advantages. Recently, Component-Based Software Development (CBSD) was proposed and has now been applied in various industry and business applications as a possible way to achieve this goal. As verified by numerous practical applications in different fields, CBSD is able to increase software development productivity as well as improve software quality. Modern embedded real-time systems have both strict functional and non-functional requirements and they are essentially safety-critical, real-time, and embedded software-intensive systems. In particular, the crucial end-to-end quality-of-service (QoS) properties should be assured in embedded systems such as timeliness and fault tolerance. Herein, I first introduce the modern component technologies and commonly used component models. Then, the middleware in distributed real-time embedded systems is discussed. Further, adaptive system resource management is elaborated upon. Finally, the prospects of a component-based approach in implementing modern embedded real-time software is discussed and future research directions are suggested. 相似文献
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周雄飞 《郑州航空工业管理学院学报(管理科学版)》2008,26(4):123-126
高技术产业集群是一种具有稳定的技术经济联系的网络体系。根据Jones等四重维度的理念、新经济社会学的结构嵌入观念以及高技术产业集群的具体特征,利用高技术产业集群的网络治理机制可以达到集群内企业互动、协调、资源的整合以及整个网络在共识下的维持和发展目标,并且可以提高高技术产业集群知识的利用效率,促进技术创新,降低创新风险。 相似文献
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<正> 1.引言 军用飞机电子设备舱中的各种电器设备需要用一定量的冷却空气进行冷却。为此需将供给电子设备舱的总供气量按所要求的比例分配给各设备。保证分配比的方法通常是在通入各电子设备的供气支管中加一相应的限流孔,由限流孔孔径的大小控制流量的多少。可见,确定满足流量要求的限流孔孔径是解决这一问题的关键。关于限流孔孔径的确定,目前尚未看到其计算方法,以往主要靠试验进行试凑。众所周知,这种试凑方法费时费力,很不经济,是一种不得已的方法。因此,笔者力图从解析角度入手,找出限流孔孔径与所 相似文献
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A method combining rotor actuator disk model and embedded grid technique is presented in this paper, aimed at predicting the flow fields and aerodynamic characteristics of tilt rotor aircraft in conversion mode more efficiently and effectively. In this method, rotor's influence is considered in terms of the momentum it impacts to the fluid around it; transformation matrixes among different coordinate systems are deduced to extend actuator method's utility to conversion mode flow fields' calculation. Meanwhile, an embedded grid system is designed, in which grids generated around fuselage and actuator disk are regarded as background grid and minor grid respectively, and a new method is presented for ‘donor searching' and ‘hole cutting' during grid assembling. Based on the above methods, flow fields of tilt rotor aircraft in conversion mode are simulated, with threedimensional Navier–Stokes equations discretized by a second-order upwind finite-volume scheme and an implicit lower–upper symmetric Gauss–Seidel(LU-SGS) time-stepping scheme. Numerical results demonstrate that the proposed CFD method is very effective in simulating the conversion mode flow fields of tilt rotor aircraft. 相似文献
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In the present work, the coefficients of thermal expansion(CTEs) of unidirectional(UD)fiber-reinforced composites are studied. First, an attempt is made to propose a model to predict both longitudinal and transverse CTEs of UD composites by means of thermo-elastic mechanics analysis. The proposed model is supposed to be a concentric cylinder with a transversely isotropic fiber embedded in an isotropic matrix, and it is subjected to a uniform temperature change. Then a concise and explicit formula is offered for each CTE. Finally, some finite element(FE) models are created by a finite element program MSC. Patran according to different material systems and fiber volume fractions. In addition, the available experimental data and results of other analytical solutions of CTEs are presented. Comparisons are made among the results of the cylinder model,the finite element method(FEM), experiments, and other solutions, which show that the predicted CTEs by the new model are in good agreement with the experimental data. In particular, transverse CTEs generally offer better agreements than those predicted by most of other solutions. 相似文献
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