A framework for analysis and design of software reference architectures

Context

A software reference architecture is a generic architecture for a class of systems that is used as a foundation for the design of concrete architectures from this class. The generic nature of reference architectures leads to a less defined architecture design and application contexts, which makes the architecture goal definition and architecture design non-trivial steps, rooted in uncertainty.

Objective

The paper presents a structured and comprehensive study on the congruence between context, goals, and design of software reference architectures. It proposes a tool for the design of congruent reference architectures and for the analysis of the level of congruence of existing reference architectures.

Method

We define a framework for congruent reference architectures. The framework is based on state of the art results from literature and practice. We validate our framework and its quality as analytical tool by applying it for the analysis of 24 reference architectures. The conclusions from our analysis are compared to the opinions of experts on these reference architectures documented in literature and dedicated communication.

Results

Our framework consists of a multi-dimensional classification space and of five types of reference architectures that are formed by combining specific values from the multi-dimensional classification space. Reference architectures that can be classified in one of these types have better chances to become a success. The validation of our framework confirms its quality as a tool for the analysis of the congruence of software reference architectures.

Conclusion

This paper facilitates software architects and scientists in the inception, design, and application of congruent software reference architectures. The application of the tool improves the chance for success of a reference architecture.     

Human foot modeling towards footwear design

Comfort test of footwear is mainly based on subjective perception of the wearer and a large number of subjects are required to obtain a reliable result. Therefore, the subjective comfort test is expensive and time consuming. Although the foot size and shape of a subject can be obtained by using a three-dimensional (3D) foot scanner, it is still difficult to create foot motion animations of each subject suitable for computer simulation.In this paper, we propose a fast approach to model foot deformation and present its application in simulating interaction with footwear towards footwear design. The simulation determines deformation of foot and footwear models. It can also determine stress distribution in the footwear. Given an initial foot model and a captured foot motion, human foot animation is created first. Then, the footwear model is fitted to the foot to compute the deformation and stress in the footwear. In this article, the boundary element method (BEM) is adopted. We demonstrate the results by conducting simulation of a captured gait motion. Experimental results showed that the method can be used to simulate human gait motion, and can determine deformation of footwear.     

A novel inverse data driven modelling approach to performance-based building design during early stages

Energy analysis at the early stage of building design is a critical, yet difficult task in performance-based design. The difficulty arises from the complex, iterative, and uncertain nature of building design and the challenges of integration with well-posed energy assessment tools. The purpose of this article is to first review characteristics of performance-based design and establish requirements for a methodology that includes generating promising design alternatives, assessing the energy performance in tandem with the generation of alternatives, and choosing an alternative design solution with confidence. The study then proposes a novel systematic data-driven method, based on linear inverse modeling that generates plausible ranges for design parameters given a preferred energy target. The energy performance in this method is described as a linear function of the design parameters for a particular scenario of design. The application of the proposed method in a case study shows that it is capable of helping designers make informed decisions regarding energy performance iteratively and confidently at the early stages of building design.     

基于Petri网的建设工程项目实施阶段工作流建模与仿真

构建一个能够准确表达实施过程系统性、动态性和不确定性的工作流模型是实现建设工程项目实施阶段工作流管理与控制的有效途径。在对建设工程项目实施阶段工作流模型特点分析及工作流概念模型构建的基础上,基于分层赋时着色Petri网构建建设工程项目实施阶段工作流模型。通过运行该工作流模型,能够获得实施阶段的信息流、资源流、异常处理、持续时间等抽象内容,不仅为实现建设项目实施阶段的工作流管理与控制提供有力的方法支持,同时也是Petri网建模技术在建设工程领域中的应用拓广。借助CPN Tools仿真平台,以一般工业与民用建筑的实施阶段为例进行工作流模型的构建与仿真,验证了基于分层赋时着色Petri网构建建设工程项目实施阶段工作流模型的正确性和有效性。     

Flow-based fabrication: An integrated computational workflow for design and digital additive manufacturing of multifunctional heterogeneously structured objects

Structural hierarchy and material organization in design are traditionally achieved by combining discrete homogeneous parts into functional assemblies where the shape or surface is the determining factor in achieving function. In contrast, biological structures express higher levels of functionality on a finer scale through volumetric cellular constructs that are heterogeneous and complex. Despite recent advancements in additive manufacturing of functionally graded materials, the limitations associated with computational design and digital fabrication of heterogeneous materials and structures frame and limit further progress. Conventional computer-aided design tools typically contain geometric and topologic data of virtual constructs, but lack robust means to integrate material composition properties within virtual models. We present a seamless computational workflow for the design and direct digital fabrication of multi-material and multi-scale structured objects. The workflow encodes for and integrates domain-specific meta-data relating to local, regional and global feature resolution of heterogeneous material organizations. We focus on water-based materials and demonstrate our approach by additively manufacturing diverse constructs associating shape-informing variable flow rates and material properties to mesh-free geometric primitives. The proposed workflow enables virtual-to-physical control of constructs where structural, mechanical and optical gradients are achieved through a seamless design-to-fabrication tool with localized control. An enabling technology combining a robotic arm and a multi-syringe multi nozzle deposition system is presented. Proposed methodology is implemented and full-scale demonstrations are included.     

面向自主运行的深空探测航天器体系结构设计 及自主任务规划方法

传统的航天器运行管控方式严重依赖地面指控、人力成本耗费大且对任务响应时间长,难以满足深空探测远距离通信时延突出的任务特点,航天器的智能化水平亟待进一步提高.本文通过对航天器自主运行问题进行系统地分析,提出一种基于多智能体的航天器自主运行的体系结构,面向自主系统结构、运行流程等进行了设计.重点针对小行星探测任务,提出了一种包含平台和载荷任务管理的两阶段航天器自主任务规划算法设计方案,能够实现平载一体的航天器自主任务管理,根据高级任务目标输出完整的指令序列.并通过自主任务规划仿真,对相关算法和模型的正确性和可行性进行了可视化验证和分析,为航天器自主运行技术研究提供了一种有益的思路和方法.     

语义特征建模系统中概念设计方案表示研究

为了提高概念设计的工作效率和设计水平,提出了一种基于语义表示法的概念设计方案的表示方法。这种方法通过语义表示法来表示模型中的特征,通过细胞元模型来管理模型数据,通过语义面将特征和设计方案表示成为具有n个语义输入和m个语义输出的黑盒,通过语义依赖图建立产品模型与特征之间的组织关系,通过力传递的方法来简化概念设计方案的推理过程。该方法不仅可以大大提高概念设计问题的求解速度,还可以为设计者提供更丰富的概念设计方案。实验证明该算法具有广泛的应用前景和实用价值。     

CALPHAD-based alloy design for advanced automotive steels - Part I: Development of bearing steels with enhanced strength and optimized microstructure

Alloy design is of prime importance for automotive steels to achieve desired properties, such as strength, hardenability and wear resistance. In the present study, CALPHAD-based computational techniques have been successfully utilized to develop advanced steels for automotive applications. The first part of this series describes an integrated computational approach for the compositional modification of bearing steels. A conventional 100CrMn6 bearing steel has been precisely redesigned to achieve strength enhancement with optimized cementite size distribution. The strength of the modified bearing steel was further improved by the addition of 0.2 wt% V using fine vanadium carbide precipitates. Experimental verification of the calculated results confirmed the reliability of the computational method employed in this study.     

单极板微位移电容传感器结构设计与优化

根据单极板微位移电容传感器结构优化设计的问题,提出了一种基于纵横推进法的电磁场仿真参数化建模方法。在建立合理的单极板电容传感器电磁仿真参数模型基础上,首先通过仿真实验选择保护环和绝缘层缺口的最优值。然后依据仿真得到的最优值,选择结构与最优值接近的电容传感器产品对比,取得了较好的研究结果,电容仿真值与实际测量值误差小于0.3%。最后对电容传感器极板倾斜对测量结果的影响进行了研究,极板倾斜2°时测量误差为1.6%。电容传感器结构优化结果满足实际工程要求。     

Recent advances in rapid multiobjective optimization of expensive simulation models in microwave and antenna engineering by Pareto front exploration

Practical engineering design problems are inherently multiobjective, that is, require simultaneous control of several (and often conflicting) criteria. In many situations, genuine multiobjective optimization is required to acquire comprehensive information about the system of interest. The most popular solution techniques are population‐based metaheuristics, however, they are not practical for handling expensive electromagnetic (EM)‐simulation models in microwave and antenna engineering. A workaround is to use auxiliary response surface approximation surrogates but it is challenging for higher‐dimensional problems. Recently, a deterministic approach has been proposed for expedited multiobjective design optimization of expensive models in computational EMs. The method relies on variable‐fidelity EM simulations, tracking the Pareto front geometry, as well as response correction. The algorithm sequentially generates Pareto‐optimal designs using a series of constrained single‐objective optimizations. The previously obtained design is used as a starting point for the next iteration. In this work, we review this technique and its modification based on space mapping surrogates. We also propose new variations exploiting adjoint sensitivities, as well as response features, which can be attractive depending on availability of derivatives or the characteristics of the system responses that need to be handled. We also discuss several case studies involving various antenna and microwave components.     

A systematic design of 1.5–9 GHz high power–high efficiency two‐stage GaAs PHEMT power amplifier

In this article, a systematic design approach for a Class‐A operated wideband power amplifier is presented. The power amplifier structure comprises of two transistors in the cascaded single stage traveling wave amplifier topology. A power amplifier was designed by using the systematic approach and fabricated with 0.25 μm GaAs PHEMT MMIC process. The amplifier has an area of 3.4 × 1.4 mm². Measurement results show that almost flat gain performance is obtained around 15 dB over 1.5–9 GHz operating bandwidth. In most of the band, with the help of a wideband load‐pull matching technique, the amplifier delivers P_o,sat and P_o,1dB of around 30 dBm and 28 dBm where the corresponding power added efficiencies are >50% and >36%, respectively. It is shown that the proposed design approach has the advantage of simple and systematic design flow and it helps to realize step‐by‐step design for the designers. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:615–622, 2014.     

Expedited simulation‐driven design optimization of UWB antennas by means of response features

In this work, a method for fast design optimization of broadband antennas is considered. The approach is based on a feature‐based optimization (FBO) concept where reflection characteristics of the structure at hand are formulated in terms of suitably defined feature points. Redefinition of the design problem allows for reducing the design optimization cost, because the dependence of feature point coordinates on antenna dimensions is less nonlinear than for the original frequency characteristics (here, S‐parameters). This results in faster convergence of the optimization algorithm. The cost of the design process is further reduced using variable‐fidelity electromagnetic (EM) simulation models. In case of UWB antennas, the feature points are defined, among others, as the levels of the reflection characteristic at its local in‐band maxima, as well as location of the frequency point which corresponds to acceptable reflection around the lower corner frequency within the UWB band. Also, the number of characteristic points depends on antenna topology and its dimensions. Performance of FBO‐based design optimization is demonstrated using two examples of planar UWB antennas. Moreover, the computational cost of the approach is compared with conventional optimization driven by a pattern search algorithm. Experimental validation of the numerical results is also provided.     

Computationally efficient design closure of miniaturized impedance matching transformers using response features

In this article, we describe a procedure for reliable and computationally efficient design optimization of miniaturized impedance matching transformers. Our approach exploits a concept of feature‐based optimization (FBO). According to FBO, considerable reduction of the computational cost of the simulation‐driven design process can be achieved—compared to conventional methods—by reformulating given performance requirements (typically, minimization of reflection over a frequency range of interest) in terms of suitably defined response features. For impedance transformer circuits, the feature points are defined as local maxima of the reflection characteristic, as well as the points defining the ?20 dB bandwidth. As the feature point coordinates (i.e., their frequencies and levels) depend on the geometry parameters of the structure in less nonlinear manner than the original responses (S‐parameters versus frequency), the optimization algorithm exhibits faster convergence. Further reduction of the optimization cost is obtained by utilization of variable‐fidelity electromagnetic simulations. Our technique is demonstrated using two design cases of an example miniaturized three‐section 50‐to‐100 ohm microstrip transformer. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:396–401, 2016.     

Analysis and modeling of World Wide Web traffic for capacity dimensioning of Internet access lines

A study on traffic characterization of the Internet is essential to design the Internet infrastructure. In this paper, we first characterize WWW (World Wide Web) traffic based on the access log data obtained at four different servers. We find that the document size, the request inter-arrival time and the access frequency of WWW traffic follow heavy-tail distributions. Namely, the document size and the request inter-arrival time follow log-normal distributions, and the access frequency does the Pareto distribution. For the request inter-arrival time, however, an exponential distribution becomes adequate if we are concerned with the busiest hours. Based on our analytic results, we next build an M/G/1/PS queuing model to discuss a design methodology of the Internet access network. The accuracy of our model is validated by comparing with the trace-driven simulation. We also investigate the effect of document caching at the Proxy server on the WWW traffic characteristics. The results show that the traffic volume is actually reduced by the document replacement policies, but the traffic characteristics are not much affected. It suggests that our modeling approach can be applied to the case with document caching, which is demonstrated by simulation experiments.     

A step toward STEP-compatible engineering data management: the data models of product structure and engineering changes

In an iterative design process, there is a large amount of engineering data to be processed. Well-managed engineering data can ensure the competitiveness of companies in the competitive market. It has been recognized that a product data model is the basis for establishing engineering database. To fully support the complete product data representation in its life cycle, an international product data representation and exchange standard, STEP, is applied to model the representation of a product. In this paper, the architecture of an engineering data management (EDM) system is described, which consists of an integrated product database. There are six STEP-compatible data models constructed to demonstrate the integratibility of EDM system using common data modeling format. These data models are product definition, product structure, shape representation, engineering change, approval, and production scheduling. These data models are defined according to the integrated resources of STEP/ISO 10303 (Parts 41-44), which support a complete product information representation and a standard data format. Thus, application systems, such as CAD/CAM and MRP systems, can interact with the EDM system by accessing the database based on the STEP data exchange standard.     

Using ergonomic digital human modeling in evaluation of workplace design and prevention of work‐related musculoskeletal disorders aboard small fishing vessels

This article seeks to present methods for preventing work‐related musculoskeletal disorders of Spanish fishermen and for redesigning the workplace aboard small fishing vessels. To achieve its objective, the research project was designed in four steps. First, the equipment and procedures for catching, handling, and storing fish were studied. Second, the work postures of all the fishermen were simulated and assessed by using an ergonomic digital human modeling system (ManneQuin Pro). Third, the work environment design aboard vessels was modified on the basis of acceptable simulated work postures to prevent repetitive movements, awkward working postures, and lower back biomechanical stresses. In the fourth step, ergonomic design parameters were provided to vessel designers. © 2011 Wiley Periodicals, Inc.     

Fast simulation‐driven feature‐based design optimization of compact dual‐band microstrip branch‐line coupler

Design of miniaturized microwave components is a challenging task. On one hand, due to considerable electromagnetic (EM) cross‐couplings in highly compressed layouts full‐wave EM analysis is necessary for accurate evaluation of the structure performance. Conversely, high‐fidelity EM simulation is computationally expensive so that automated determination of the structure dimensions may be prohibitive when using conventional numerical optimization routines. In this article, computationally efficient simulation‐driven design of a miniaturized dual‐band microstrip branch‐line coupler is presented. The optimization methodology relies on suitably extracted features of a highly nonlinear response of the coupler structure under design. The design objectives are formulated in terms of the feature point locations, and the optimization is carried out iteratively with the linear model of the features utilized as a fast predictor. The entire process is embedded in the trust‐region framework as convergence safeguard. Owing to only slightly nonlinear dependence of the features on the geometry parameters of the circuit at hand, the optimized design satisfying prescribed performance requirements is obtained at the low computational cost of only 24 high‐fidelity EM simulations of the structure. Experimental validation of the fabricated coupler prototype is also provided. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:13–20, 2016.     

EarlyData knowledge base for material decisions in building design

To make use of the great opportunities for emission reduction in early building design, future emissions need to be calculated when only geometric, but no detailed material information about a building is available. Currently, early design phase life cycle assessments (LCAs) are heavily reliant on assumptions of specific material choices, leading to single point emission values which suggest a precision not representative for an early design stage. By adding knowledge about possible locations and functions of materials within a building to life cycle inventory (LCI) data, the EarlyData knowledge base makes LCA data sets accessible and more transparent. Additionally, “generic building parts” are defined, which describe building parts independently of precise material choices as a combination of layers with specific functions. During evaluation, enriched LCI data and generic building parts enable assessment of a vast number of possible material combinations at once. Thus, instead of single value results for a particular material combination, ranges of results are displayed revealing the building parts with the greatest emission reduction potential. The application of the EarlyData tool is illustrated on a use case comparing a wood building and a concrete building. The database is developed with extensibility in mind, to include other criteria, such as (life cycle) costs.