An integrated modeling and design tool for advanced optical spacecraft

In order to provide engineering students with the opportunity to integrate engineering science principles, use computer-based analysis and design tools and computer-controlled machine tools, and strengthen their design and synthesis skills, we have developed a course in computer-assisted product realization. In the course the students are assigned a product production task and they are required to develop a product concept, engineer the product using computer-based design and analysis tools, select a material, design the manufacturing process using numerical simulations, design and make the tools, and produce sample products. This course is meeting the goals of integrating design, analysis, and production and is providing students with experience in the practice of engineering.

Looking back at the history of control engineering, one finds that technology and ideas combine themselves until they reach a successful result, over the timeline of several decades (Bernstein, 2002). Simple dynamical compensators (such as PID, Phase-Lead, Phase-Lag, etc) have done in the past a remarkably good and efficient job in real-life control applications. Theoretical insight in the closed-loop behavior is provided by powerful and well-developed theories – which are considered as basic knowledge for every control engineer – such as the Root Locus and the Frequency Response techniques. In the past, these theories have been extensively used as analysis tools – e.g. the stability analysis of a given control system based on closed loop poles (Root Locus RL) or Nyquist criterion (Frequency Response FR). However, analysis implies that a controller is already available, irrespective of its design method. Nowadays, thanks to the computational and graphical power of modern computers, many of these theories can be implemented as interactive graphical design tools. In this way, control engineering moves away from being an abstract and mathematical-oriented discipline and it evolves gradually towards a mature engineering discipline. An extensive reflection upon the role of information science in control engineering has been given in (Dormido, 2004). This new way of interactive control education provides practical insights into control systems fundamentals (Wittenmark et al, 1998; Dormido et al, 2002). Such combinations of interactive environment and animation bring visualization to a new level and aid learning and active participation by control engineering students (Kheir et al, 1996; Johansson et al, 1998). Recently, a Root Locus RL toolbox has been introduced in Matlab – in this chapter, a Frequency Response toolbox (FRtool) will be presented. Although some other computer aided design (CAD) tools based on frequency response have been developed in the past (Balakrihsnan & Boyd, 1994; Satoh et al, 1994; Piguet & Gillet, 1997; Pouliz & Pouliezos, 1997; Piguet et al, 1999), the one presented in this contribution is highly interactive, graphical, easy-to-use and posing an elegant simplicity (especially for non-experts, as limited control engineering insight is required). The Matlab® controller design tool based on the root locus method (rltool) cannot handle systems with time-delay without approximating the dead5

A quasi-2D thermodynamic model for performance analysis and optimization of liquid hydrogen storage system with multilayer insulation and vapor-cooled shield

During the last decade, the local manufacturing of small wind turbines is becoming an increasingly common approach in rural electrification applications, especially among international networks of renewable energy practitioners. As the number of locally manufactured small wind turbine installations is increasing on all continents, supply chain issues, material shortages or design issues in custom applications are becoming evident. In this paper the development of a series of open access design and analysis tools is presented, which allows the local manufacturer to redesign the small wind turbine according to available materials. In the two case studies, the design tools are used in the field by practitioners in order to overcome supply chain issues during the implementation and design phases of rural electrification projects in Ethiopia and Nepal.

This paper presents an exploration of the Simulation Based Research and Development through an in-house technology assessment of a Sensorcraft concept. The goals of SBR&D are: to reduce the time and cost for developing and maturing promising technology, to integrate the technologist and the warfighter into the Science and Technology (S&T) acquisition process, and to provide analytical input into the Air Force S&T planning process. SBR&D combines a variety of critical research and technology-development capabilities, including engineering-level modeling, design, and analysis tools, mission- and campaign-level simulations, cost analysis tools, and database tools in a networked, distributed environment. Early SBR&D capabilities combine high fidelity manned and unmanned vehicle simulations to create a common synthetic battlespace for technology assessment in a mission environment. The simulation environment is being combined with engineering models, design tools, and an intelligent database to allow differing degrees of fidelity to be used at different times and in different parts of a simulation analysis. The study presented here represents an attempt to show the SBR&D process in action and to identify deficiencies in the process. Once established, the SBR&D process will provide the capability for researchers to evaluate the impact of different technologies in a warfighting environment, providing a link between AFRL technologies and warfighter mission needs.

Probabilistic Analysis Tools for Surface Ships Under Seaway and Extreme Dynamic Loads

Reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, as well as the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. Thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to further analyse the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. The proposed design methodology is capable, with the utilised tool, of exploring the interaction of design criteria and providing critical design insight at engine-aircraft system level. Previous work by the authors focused on understanding the design space for this particular configuration with minimum specific fuel consumption, engine weight and mission fuel in mind. This was achieved by means of a parametric analysis, varying several engine design parameters — but only one at a time. The present work attempts to identify “globally” fuel burn optimal values for a set of engine design parameters by varying them all simultaneously. This permits the non-linear interactions between the parameters to be accounted. Special attention has been given to the fuel burn impact of the reduced HPC efficiency levels associated with low last stage blade heights. Three fuel optimal designs are considered, based on different assumptions. The results indicate that it is preferable to trade overall pressure ratio and pressure ratio split exponent, rather than specific thrust, as means of increasing blade height and hence reducing the associated fuel consumption penalties. It is interesting to note that even when considering the effect of HPC last stage blade height on efficiency there is still an equivalently good design at a reduced overall pressure ratio. This provides evidence that the overall economic optimum could be for a lower overall pressure ratio cycle. Customer requirements such as take-off distance and time to height play a very important role in determining a fuel optimal engine design. Tougher customer requirements result in bigger and heavier engines that burn more fuel. Higher overall pressure ratio intercooled engine cycles clearly become more attractive in aircraft applications that require larger engine sizes.

Reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, as well as the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. Thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is very little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to analyse the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. With minimum mission fuel in mind, the results indicate as optimal values a pressure ratio split exponent of 0.38 and an intercooler mass flow ratio just below 1.2 at hot-day top of climb conditions. At ISA mid-cruise conditions a specific thrust of 86m/s, a jet velocity ratio of 0.83, an intercooler effectiveness of 55% and an overall pressure ratio value of 76 are likely to be a good choice. A 70,000lbf intercooled turbofan engine is large enough to make efficient use of an all-axial compression system, particularly within a geared fan configuration, but intercooling is perhaps more likely to be applied to even larger engines. The proposed optimal jet velocity ratio is actually higher than the value one would expect by using standard analytical expressions primarily because this design variable affects core efficiency at mid-cruise due to a combination of several different subtle changes to the core cycle and core component efficiencies at this condition. Analytical expressions do not consider changes in core efficiency and the beneficial effect of intercooling on transfer efficiency, nor account for losses in the bypass duct and jet pipe, whilst a relatively detailed engine performance model such as the one utilised in this study does. Mission fuel results from a surrogate model are in good agreement with the results obtained from a rubberised-wing aircraft model for some of the design parameters. This indicates that it is possible to replace an aircraft model with specific fuel consumption and weight penalty exchange rates. Nevertheless, drag count exchange rates have to be utilised to properly assess changes in mission fuel for those design parameters that affect nacelle diameter.

Today, the advent of the multi-million transistor chip offers the opportunity to provide more integrated functionalities into a single silicon die. This is both a clear advantage to improve existing products and a hard challenge to cope with. Unfortunately, today's available design methodologies and tools are not sufficiently advanced to exploit the full potential of such large silicon flexibility. On one hand, the design of complex system-on-chip requires new tools for the analysis and optimization of embedded software, which should extend the standard tool chain consisting of complier, debugger and simulator. On the other hand, the development of such tool chain for a new microprocessor requires a substantial time effort which is no more compatible with actual market dynamics. In STMicroelectronics, we developed a technology which tries to tackle such a double-face problem by adding several retargetability features to a standard tool chain and by providing new tools for code analysis.

A close-form solution for the maximum-power operating point of a solar cell array

A vector sensor measures the scalar and vector components of the acoustic field. In a multipath channel, the sensor collects the information via multiple paths. Depending on the angle-of-arrival distribution and other channel characteristics, different types of correlation appear in a vector sensor array, which affect the array performance. In this paper, a novel statistical framework is developed which provides closed-form parametric expressions for signal correlations in vector sensor arrays. Such correlation expressions serve as useful tools for system design and performance analysis of vector sensor signal processing algorithms. They can also be used to estimate some important physical parameters of the channel such as angle spreads, mean angle of arrivals, etc.

The extensive application of ground-coupled heat pump system (GCHP) is restricted by the installation of conventional borehole ground heat exchangers (GHE). Combining the GHE and building foundation piles as “energy piles” can eliminate the drilling cost and land area requirement of a conventional borehole GHE. In this study, the accurate analytical thermal analysis is carried out for simulating the heat transfer process of the novel pile GHE with spiral coils. The temperature responses of the coil pipe wall and the circulating water entering/effusing the pile GHE to the short time step heat transfer loads are deduced based on the established analytical transient three-dimensional spiral source model. Then the operation performance as well as the heat exchange capacity of novel pile GHE is investigated and compared with conventional borehole GHE. The analytical solutions developed in this study can provide an appropriate and convenient tool for thermal analysis and design of the novel foundation pile GHE with spiral coils. It is believed to be a new contribution in the foundation pile GHE field.

Arnold Engineering Development Center (AEDC) has designed and built a high-speed data acquisition and processing system for real-time online dynamic data monitoring and analysis. The Computer Assisted Dynamic Data Monitoring and Analysis System (CADDMAS) provides 24 channels at high frequency and another 24 channels at low frequency for online real-time aeromechanical, vibration, and performance analysis of advanced turbo-engines and other systems. The system is primarily built around two different parallel processors and several PCs to demonstrate hardware independence and architecture scalability. These processors provide the computational power to display online and in real-time what can take from days to weeks using existing offline techniques. The CADDMAS provides online test direction and immediate hardcopy plots for critical parameters, all the while providing continuous health monitoring through parameter limit checking. Special in-house developed Front End Processors (FEP) sample the dynamic signals, perform anti-aliasing, signal transfer function correction, and bandlimit filtering to improve the accuracy of the time domain signal. A second in-house developed Numeric Processing Element (NPE) performs the FFT, threshold monitoring, and packetizes the data for rapid asynchronous access by the parallel network. Finally, the data are then formatted for display, hardcopy plotting, and cross-channel processing within the parallel network utilizing off-the-shelf hardware. The parallel network is a heterogeneous message-passing parallel pipeline configuration which permits easy scaling of the system. Advanced parallel processing scheduler/controller software has been adapted specifically for CADDMAS to allow quasi-dynamic instantiation of a variety of simultaneous data processing tasks concurrent with display and alarm monitoring functions without gapping the data. Although many applications of CADDMAS exist, this paper describes the features of CADDMAS, the development approach, and the application of CADDMAS for turbine engine aeromechanical testing.

Performance analysis and optimization of organic Rankine cycle (ORC) for waste heat recovery

Multi-objective design optimization of battery thermal management system for electric vehicles