基于角色的访问控制技术在考务管理系统中的应用

访问控制是信息安全的一个重要保障。在介绍RBAC模型的基础上,根据考务管理系统中用户职责,规定用户访问权限,定义考务管理系统中的角色及其对应的权限,阐述RBAC在考务管理系统中的应用,为考务管理系统的访问控制安全提供一种思路。     

物联网访问控制策略探析

随着计算机技术的快速发展,各种物联网应用在人们生活中越来越多,因而物联网安全问题也更加引人关注。针对物联网安全中的访问控制问题,分析物联网分层结构中各层的安全需求,给出联网的环境下的访问控制策略供参考。     

基于高炉TRT系统控制技术的研究与改进

介绍高炉TRT控制系统的改进,以达到节能、降噪、环保的目的.     

自动焊机监测与参数化曲线控制系统设计

设计了自动焊机的监测与参数化曲线控制系统,以可视化方式为工艺人员改变焊接过程的控制参数提供了便利,该控制系统的数据库的数据存储与查询功能为工艺人员进行离线工艺分析提供了大量的数据,且该系统与焊机的数控系统密切配合,实现了焊接自动生产线的可靠监控.     

Optimal maintenance planning for sustainable energy efficiency lighting retrofit projects by a control system approach

The energy savings achieved by implementing energy efficiency (EE) lighting retrofit projects are sometimes not sustainable and vanish rapidly given that lamp population decays as time goes by if without proper maintenance activities. Scope of maintenance activities refers to replacements of failed lamps due to nonrepairable lamp burnouts. Full replacements of all the failed lamps during each maintenance interval contribute to a tight project budget due to the expense for the lamp failure inspections, as well as the procurement and installation of new lamps. Since neither “no maintenance” nor “full maintenance” is preferable to the EE lighting project developers (PDs), we propose to design an optimal maintenance plan that optimises the number of replacements of the failed lamps, such that the EE lighting project achieves sustainable performance in terms of energy savings whereas the PDs obtain their maximum benefits in the sense of cost–benefit ratio. This optimal maintenance planning (OMP) problem is aptly formulated as an optimal control problem under control system framework, and solved by a model predictive control (MPC) approach. An optimal maintenance plan for an EE lighting retrofit project is designed as a case study to illustrate the effectiveness of the proposed control system approach.     

Non-diagonal H∞ weighting function design: Exploiting spatio-temporal deformations in precision motion control

Model-based control design requires a careful specification of performance and robustness requirements. In typical norm-based control designs, performance and robustness requirements are specified in a scalar optimization criterion, even for complex multivariable systems. This paper aims to develop a novel approach for the formulation of this optimization criterion for multivariable motion systems that exhibit spatio-temporal deformations. To achieve this, characteristics of the underlying system are exploited to design multivariable weighting functions. In contrast to pre-existing approaches, which typically lead to diagonal weighting functions, the proposed approach enables the design of non-diagonal weighting functions. Extensive experimental results confirm that the proposed procedure can significantly improve the performance of an industrial motion system compared to earlier approaches.     

Influence of groove type on welding-induced residual stress,deformation and width of sensitization region in a SUS304 steel butt welded joint

To join a medium or thick plate weldment with a full penetration, a groove is usually prepared in the space between two sections of metal. Because weld metal needs to be deposited within the groove to form the joint, it is expected that different groove type will require different heat input, which may consequently have influence on welding residual stress and deformation. Generally, different groove corresponds to different bead layout, so it can be foreseen that the groove type has a significant effect on temperature history, shape and size of heat affected zone, and region of sensitization in certain alloys such as austenitic stainless steel. The influences of groove type on residual stress, angular distortion and width of sensitization region in a SUS304 butt-welded joint were investigated by means of numerical simulation and experiment. Based on ABAQUS code, a computational approach with considering thermo-mechanical coupling behaviors, moving heat source, strain hardening and annealing effect was developed to simulate temperature profile, stress field and deformation in multi-pass joint. Welding temperature cycles, residual stress distributions and deformations in V, K and X groove joints were calculated through using the proposed computational procedure. Meanwhile, experiments were carried out to obtain residual stress distributions and angular distortions. Through comparing the numerical results and the measured data, the effectiveness and accuracy of the developed computational approach were verified. The simulation results show that groove type has a significant influence on welding residual stress distribution, angular distortion and width of sensitization region.     

天然气长输管道燃驱机组控制系统优化技术

燃气轮机驱动的压缩机组被广泛地应用在天然气长输管道,其控制系统优化技术的大范围深度应用在管道行业尚数首次,及时消除生产瓶颈的同时,也为涉及燃机的控制专业同行提供了技术借鉴,更重要的是为管道行业燃机运行提供了安全保障。     

多螺旋桨太阳能无人机俯仰控制方法研究

在太阳能无人机飞行俯仰控制的研究中,为更好地满足太阳能无人机长航时的飞行要求,提出一种采用由多螺旋桨差动推力产生俯仰力矩从而达到俯仰控制效果的新型控制方法。太阳能无人机机翼的柔性结构特点造成飞行过程中螺旋桨产生纵向位移,为多螺旋桨差动控制提供了基础。由于多螺旋桨是过操纵机构,引入加权伪逆方法对多螺旋桨输入冗余进行控制分配,并与传统的升降舵LQR控制方法进行对比分析。仿真结果表明,多螺旋桨差动推力俯仰控制方法能达到良好的控制效果,且比传统升降舵控制更符合太阳能无人机飞行特点和可靠性要求,为太阳能无人机实现无气动舵面飞行控制提供了理论依据。     

基于PC的智能家电无线红外遥控系统

基于PC的智能家电遥控系统是以单片机CC2530为核心驱动、以YS-IR01F为红外学习核心模块的控制系统,该系统包括三部分,分别为用户控制界面、网关模块以及底层红外驱动模块,该系统可以通过对家用红外遥控数据的学习进而实现利用PC用户界面控制包括电视、投影仪等普通家电,初步实现家电智能化。满足一般家庭对智能家居的要求,方便人们的生活。