Algorithms for Power Converter Design Optimization

A practical optimization approach for power converters is established which allows conception of a design to meet all powercircuit performance requirements and concurrently to optimize a defined quantity such as weight or losses. In addition to facilitating a cost effective design, the computer-aided approach provides a means to readily assess a) the weight-efficiency tradeoff, b) impacts of converter requirements and component characteristics on a given design, and c) optimum power-system configurations. The following two popular algorithms for nonlinearly constrained optimization are utilized to design the power converter: 1) the sequential unconstrained minimization technique, SUMT Version 4; 2) the ALAG penalty function technique, ALAG5. These algorithms are compared, and suggestions are made for improving the efficiency of the optimization algorithms for power converter design.     

飞机结构初步设计优化中的损伤容限优化方法研究

本文提出并研究了一种在飞机初步设计阶段考虑损伤容限要求优化设计的方法.首先,通过许用应力形式来体现并表征损伤容限设计要求,作为一类新的设计约束,用于初步设计阶段的结构优化设计.然后,通过Global/local分析,在整体优化设计中考虑局部疲劳需求;根据疲劳寿命要求,用裂纹扩展分析程序AFGROW确定了一个新的强度准则...     

Mechanical engineering's role in multi-disciplinary radar design

Successful execution of a program and full satisfaction of the customer's requirements is a challenge for any contractor. Raytheon Company responds to this challenge by following a proven program execution methodology. The methodology includes all program aspects from financial planning to engineering to validation and test. This discusses the engineering team and the role of the mechanical engineer. A radar system is ultimately an assembly of advanced electronics and software. However, the design, fabrication, assembly, integration, and test Of this complex system requires a coherent multi-disciplinary approach. Raytheon, like many contractors, chooses to assemble an integrated product team (IPT) including all engineering disciplines. Mechanical engineering is integral to satisfying performance requirements, performing preliminary and detailed design, transition of the design to manufacturing, and implementation of the hardware in the field. During definition, mechanical engineering assists fundamental architecture development, conceptual design, and requirements development which precludes issues that are sometimes ignored to the detriment of many programs. These design issues include environmental protection, structural stiffness to meet deflection requirements, cooling system capacity to properly remove dissipated heat, manufacturabilit3' to control cost, maintainability to enable repair in the field, and transportability. Recognizing and trading off these issues early greatly increases the Probability Of satisfying customer objectives. This discusses the approach Raytheon is taking to ensure an overall multi-disciplinary solution to our design challenges from the perspective of the mechanical engineer.     

复合材料飞机结构损伤容限和耐久性设计初探

虽然军机和民机规范对复合材料结构的损伤容限和耐久性均提出了要求,但迄今为止尚无成熟的设计方法可用。本文试图通过对国外经验的归纳总结,并结合自己的研究成果,提出一种切实可行的方法供参考。限于篇幅,本文仅就加筋结构蒙皮遇到的几个问题进行讨论。     

系统工程在大型客机运行支持系统研制中的应用综述

将商用飞机系统思想应用于产品运行支持系统研制过程中,从利益攸关方需要定义、功能分析、需求定义和适航约束限制、系统架构定义、接口定义、设计综合、验证确认到运行评审,完整地分析了产品运行支持系统研制的全过程,并给出产品运行支持系统全生命周期过程的模型与定义。该方法可以有效地将大型客机产品运行顶层需求分解至产品研制和运行支持系统研制需求中,并且通过过程集成以及技术集成将运行支持系统研制与飞机研制相结合,从而保证大型客机在满足适航型号合格审定（TC）和航空器评审（AEG）要求的同时,能够满足客户实际运行安全性和经济性需求。     

Portable approach landing system design

This paper presents a design concept for an azimuth and an elevation antenna suitable for the light weight Portable Approach Landing System (PALS). The proposed design complies with the requirements of the International Civil Aviation Organization (ICAO) Annex 10. Based on a proven technology, the proposed design offers a low risk and a cost effective approach     

Designing to MIL-STD-2165: Testability

The V-22 avionic hardware is the first to be designed under MIL-STD-2165 testability program requirements. This paper presents an overview of the avionics design-for-testability approach and lessons learned to date relative to the application of MIL-STD-2165. The paper will discuss incorporation of testability requirements up front in the avionics design which will drive the supportability philosophy at both the Organizational and Depot levels of maintenance. The paper will compare previous avionics hardware testability requirements versus those applied to the V-22 avionics and highlight areas of improvement. A discussion of testability design impacts on reduced level of testing (i.e. WRA/SRA/System) will be included. In addition, the paper discusses an innovative approach to meeting the user requirements for a man-portable forward deployed maintenance capability that forms the basis for a two level support scenario (Organizational and Depot). The innovation comes from the fact that the on-board Central Integrated Checkout system will provide data as well as fault isolation and will use this data as a mechanism to reduce the size and complexity of the stimulus and measurement hardware at either the Organizational or Depot level depending on the deployment requirements.     

Comprehensive sizing and optimization method for series-hybrid unmanned convertiplane

This paper presents a novel sizing and optimization approach for the emerging series-hybrid unmanned convertiplane, which can be used to translate the top-level design requirements into the design parameters corresponding to the optimal power supply strategy and minimum total takeoff weight. The method comprehensively considers the design constraints in the rotor, fixed-wing, and transition modes, and pays special attention to the characteristic response of Series Hybrid Electric System (S-HES) in complex application scenarios, especially the coupling of battery power, energy, and state-of-charge under high-power discharge conditions, the variation of fuel economy, and the adjustment of power supply strategy. With proposed method, it’s possible to rapidly explore the design space in the initial design stage and find out the optimal design results with high confidence. A case study was proposed to verify the approach. The results reveal the particularity of convertiplane in terms of power requirements, and prove the necessity to consider detailed S-HES characteristic responses during parameter determination. The optimal design parameters were obtained through the hybrid control parameter optimization, which verified the effectiveness of proposed method. Possible errors and corresponding correction methods were also presented.     

基于遗传算法的起落架布局设计技术

起落架布局是飞机概念设计阶段十分重要的一环。本文基于遗传算法原理进行起落架布局设计,利用设计中的限制条件和设计经验,确定起落架布局参数的设计空间,通过遗传算法的并行计算,依据目标函数快速高效地确定起落架布局设计的最优方案。     

大展弦比飞机翼身结构不同刚度对结构响应的影响

为了研究大展弦比双机身布局无人机翼身结构不同刚度对结构响应的影响,本文采用有限元分析与满应力优化相结合来探讨这一问题。计算结果表明:机翼与机身之间不同刚度对结构响应存在影响。建议结构设计时注意这一现象并加以利用,从而得到轻量化的结构设计。针对算例进一步计算与分析表明:采用本文方法得到的结构优化方案,同样也能够满足该飞机的静、动气弹要求。结论:采用本文方法,不仅可以研究飞机部件之间不同刚度对飞机结构响应的影响,还可以进行全机的结构方案设计,并对此方案进行刚度、强度、颤振和控制面效率的分析与评估。     

The THEMIS Magnetic Cleanliness Program

The five identical THEMIS Spacecraft, launched in February 2007, carry two magnetometers on each probe, one DC fluxgate (FGM) and one AC search coil (SCM). Due to the small size of the THEMIS probes, and the short length of the magnetometer booms, magnetic cleanliness was a particularly complex task for this medium sized mission. The requirements leveled on the spacecraft and instrument design required a detailed approach, but one that did not hamper the development of the probes during their short design, production and testing phase. In this paper we describe the magnetic cleanliness program’s requirements, design guidelines, program implementation, mission integration and test philosophy and present test results, and mission on-orbit performance.     

THEMIS Ground Based Observatory System Design

The comprehensive THEMIS approach to solving the substorm problem calls for monitoring the nightside auroral oval with low-cost, robust white-light imagers and magnetometers that can deliver high time resolution data (0.33 and 2 Hz, respectively). A network of 20 Ground-Based Observatories (GBOs) are deployed across Canada and Alaska to support the collection of data from these instruments. Here we describe the system design of the observatory, with emphasis on how the design meets the environmental and data-collection requirements. We also review the design of the All Sky Imager (ASI), discuss how it was built to survive Arctic deployments, and summarize the optical characterizations performed to qualify the design to meet THEMIS mission requirements.     

基于非概率模型的结构稳健可靠性设计方法

 基于非概率可靠性理论,将稳健设计和稳健可靠性的思想和方法用于结构设计,提出了结构的稳健可靠性设计方法。把结构设计归结为满足可靠性要求的多目标优化。其中,以非概率可靠性指标为约束,以极小化结构重量 (或造价)和极大化对不确定因素的稳健性为目标。目的在于使结构在满足可靠性要求的前提下,其重量 (或造价)和对不确定因素的稳健性达到协调最优。在不确定参量的已知数据很少的情况下,本方法为结构的可靠性设计提供了一种可能的选择。数值算例说明了文中方法的应用。     

Benefits and challenges of Integrated Sensor Systems

Projection of avionics system costs shows unacceptable escalation as a percentage of flyaway cost. Time sharing of RF modules between Radar, EW and CNI offers savings. The Air Forces' PAVE PACE program defined the benefits and initial architecture approaches. From this, an optimum Integrated Sensor System (ISS) design was defined that reduces the life cycle cost of the fleet of vehicles using the common modules. The ISS program will design, build and test modules to prove the approach. Challenges to overcome include system complexity, real time control, test and calibration, and diagnostics. The most stressing requirements were determined by analyzing requirements for Radar, EW and CNI. Open interface specifications and module partitioning were developed that can meet all the requirements     

Multi-objective approach in GNSS code discriminator design

In spread spectrum ranging system receivers such as the Global Navigation Satellite System (GNSS) receivers, a discriminator is used in the code tracking loop to provide an error signal for the tracking of incoming signals. Typically, the discriminator manipulates several correlator outputs to form the correction signal. A multi-objective approach is adopted here to design the coefficients associated with a multi-correlator-based discriminator to lead to a better performance tradeoff in large tracking range, acceptable multipath-induced bias, high sensitivity, free of ambiguity, and small variance. It is shown that the multiple-objective problem can be tackled via a quadratic/linear programming method, rendering the optimal coefficient vector for the implementation of the discriminator. In addition, as the discriminator design is often subject to conflicting requirements, it is shown that the proposed design approach is capable of establishing bounds on achievable performance. Examples with respect to BPSK (binary phase-shift keying) NRZ (nonreturn-to-zero), and BOC (binary-offset carrier) signals are given to illustrate the design approach.     

Lessons learned using software-assisted systems engineering on large satellite development contracts

Over the years, the world's defense industries have become quite proficient at developing large, complex hardware and software systems. In recent years, the ubiquitous deployment of personal computers has changed the way we work. Additionally, took designed to facilitate systems engineering have recently matured enough to start having a major impact on many major systems development efforts. Finally, the government's faster-better-cheaper acquisition philosophy has started driving prime contractors to a concurrent engineering approach toward systems engineering. This confluence of experts is has had unexpected impacts on both the flexibility and rigor of requirements management processes. While the maturing requirements and design took hold great promise in maintaining requirements traceability throughout the design process, the widespread use of desktop computing systems has inadvertently lulled many experienced systems engineers into sloppy processes because it now appears to be a simple matter to make a requirements change in a softcopy of a requirements document. Without strong process and management support, requirements changes inevitably start being derived in a broad spectrum of incompatible took and formats. This author is currently participating in the design phase of a major classified government satellite development effort. As an integral member of an extremely experienced requirements management team (boasting over 150 years of combined experience in the defense industry), this author has had the opportunity to watch the team navigate straight into many of the systems engineering potholes created when talented engineers implement concurrent engineering using a variety of tools without a consistent process framework. This paper, therefore, specifically addresses process and implementation challenges that arose when establishing a software-assisted concurrent-engineering approach on a large satellite development contract.     

Design Optimization for a Half-Bridge DC-DC Converter

A nonlinear programming technique using the penalty function method is employed for the minimum weight design of a halfbridge dc-dc buck power converter. The cost-effective computeraided approach provides a minimum weight design down to the details of the component level which concurrently meets all power circuit performance requirements. Important design insights and guidelines are obtained to readily assess 1) the tradeoffs between weight and loss as the switching frequency is increased, 2) the optimum operating frequency range over which the total weight/loss is minimized, 3) the impact of device characteristics on the total weight and loss profile.     

舰载机着舰时航迹稳定性研究

本文讨论了舰载飞机以小于有利速度着舰时的航迹稳定性问题。在分析飞机航迹稳定性的同时,还对油门杆控制、机动襟翼控制对改善航迹稳定性的作用进行了初步探讨;在此基础上还讨论了舰载飞机加装波束导引系统对着舰过程的影响原理。结果表明:采用油门杆控制、机动襟翼控制来改善着舰阶段的航迹稳定性是可行的:而且用以上两控制系统作为内环的自动驾驶仪在波束导引系统自动导引飞机着舰过程中,能控制飞机的飞行速度、高度,帮助驾驶员操纵。     

V-22 mechanical diagnostic design approach

The requirements and diagnostic applications for the V-22 tiltrotor aircraft are used to demonstrate the unique requirements of mechanical system diagnostic design. The rationale for the approach selected is explored, and it is shown how the mechanical system diagnostic requirements affect the avionics architecture and performance requirements. It is concluded that, in light of the underdeveloped nature of mechanical diagnostics technology and the extended time required for a given mechanical diagnostic design to mature, future avionics system designs need architecture that is adaptable enough to accommodate the evolving mechanical diagnostics     

民用飞机着陆系统安全性评估的故障树分析

飞机着陆系统是保障飞机安全进近着陆的关键系统,如何评估着陆系统满足安全性设计要求是系统设计的重要环节之一。阐述民用飞机安全性评估的基本流程,以微波着陆系统为例,针对给定的微波着陆系统框图,通过故障树分析方法,对完全丧失两侧微波着陆信息的失效状态进行定量评估,重点详述建树过程和建树方法。结果表明:故障树分析对系统架构的设计具有重要的指导作用,二者紧密结合、相互反馈;特别是当失效状态所对应的概率要求无法满足时,借助故障树分析产生的割集报告,能找出系统架构存在的薄弱之处和关键部位,从而采取有效的应对措施,完成对系统架构的优化设计。