浅谈测量误差与不确定度

本文对测量误差和测量不确定度的定义、来源及分类进行描述。通过对测量误差和测量不确定度的区别及比较,阐述了用测量不确定度取代测量误差评定测量结果的必然性。     

An object-oriented modeling framework for representing uncertainty in early variant design

This article presents a framework for the representation of uncertainty in the early design of complex adaptive products such as automobiles. The core of the framework is an object-oriented approach in which design objects and their inter-relationships may be modeled, and in which both the design attributes and the product structure may be uncertain. Relationship objects allow product variants and design alternatives to be represented. In addition to the design model, derivation methods for design attributes may be modeled, and methods may be incorporated to allow the deterministic or probabilistic computation of attributes. The modeling framework is the basis of a risk modeling tool, RiTo, in which Monte Carlo simulation is used to compute estimates for costs and other design attributes together with their probability of achievement in the final design. Uncertainties may be aggregated and levels of uncertainty in different parts of the model may be continually analysed and assessed. The framework also provides a mechanism for accumulating product knowledge, in particular knowledge concerning relationships between elements of part and assembly models, product volumes and manufacturing considerations.

Validation and error estimation of computational models

This paper develops a Bayesian methodology for assessing the confidence in model prediction by comparing the model output with experimental data when both are stochastic. The prior distribution of the response is first computed, which is then updated based on experimental observation using Bayesian analysis to compute a validation metric. A model error estimation methodology is then developed to include model form error, discretization error, stochastic analysis error (UQ error), input data error and output measurement error. Sensitivity of the validation metric to various error components and model parameters is discussed. A numerical example is presented to illustrate the proposed methodology.     

An ethnographic study of design knowledge reuse in the architecture, engineering, and construction industry

This paper presents an ethnographic study of knowledge reuse in the architecture/engineering/construction industry. Reuse occurs largely through social knowledge networks. Even when reuse from an external repository occurs, a human expert is needed to provide input on what to reuse and contextual information about the designs being reused. This is attributed to the effectiveness of internal knowledge reuse, the reuse of knowledge from one’s personal experiences. Internal knowledge reuse is effective because the designer can find items to reuse, and can recall the context of these items and can therefore understand them. This ethnographic study was used to develop a corporate memory, a rich, detailed repository of knowledge in context. The corporate memory will support finding and understanding. Understanding can be brought about by enabling the designer to explore the item’s context. This helps the designer to manage the tradeoff between productivity and creativity in deciding what to reuse.     

Functional characterisation of mechanical joints to facilitate its selection during the design of open architecture products

New trends in product design require the use of modularity as key feature aimed to improve functional performance and the generation of open architecture products. For mechanical systems, one of the challenges during early design stages of these products involves the proper selection of joining methods among their constructive components. A robust joint selection process must consider product requirements, life cycle analysis and eventual procedures for assembly and disassembly. However, the general approach towards a Design-for-Assembly (DFA)/Design-for-Disassembly (DFD) only considers design, manufacturing and in some cases final disposal stage. Additionally, most of the works found in the literature are merely focused on assembly operations, disregarding economic and environmental benefits from optimising disassembly complexity. Herein, a functional characterisation of mechanical joint methods for the assembly and disassembly activities that take place throughout the product life cycle is proposed, focusing on open architecture products. Additionally, a classification of joining methods, a joint complexity metric valuation and a selection process are proposed for the conceptual design stage. The approach integrates both DFA and DFD principles in a formal methodology. The proposed selection roadmap can be implemented to increase product sustainability positively regarding resources optimisation, operational time and costs in reuse, remanufacturing and recycling tasks.     

The use of nested desirability functions and quality indices for multi-response robust parameter design problems

A multi-response robust parameter design (RPD) problem-solving technique based on desirability functions is presented in which the means and variances of all responses are placed on a level playing field. The proposal allows a decision maker to integrate their preferences for the individual means and variances. It is shown that the ensuing operating point is a system setting that produces a mutually robust set of responses. In addition, this article offers an approach to assess several RPD strategies via quality indices. The measures presented here allow for a more knowledgeable and comprehensive evaluation of the competing RPD strategies.     

Postponing design processes in unpredictable environments

This work explores the effectiveness of design postponement in the concept development of large-scale engineering projects. Our empirical research shows limited use of postponement in semiconductor fabrication facility (fab) projects despite evidence that the customer inevitably requests design criteria changes in the projects life. We simulate fab concept development as a 2-stage process—conceptualization followed by design. We find that postponing the start of design in relation to the completion of conceptualization reduces the average resources spent on design and the variability in the concept development duration but increases the average concept development duration. A sensitivity analysis on the postponement lag duration indicates, however, that some degree of postponement may allow reducing design rework without increasing the risk of overrunning the project completion date, in comparison to the risk with early commitment. Further, simulation indicates that the effectiveness of postponement decreases as designers capability to reuse work increases.

Simulation optimization for revenue management of airlines with cancellations and overbooking

This paper develops a model-free simulation-based optimization model to solve a seat-allocation problem arising in airlines. The model is designed to accommodate a number of realistic assumptions for real-world airline systems—in particular, allowing cancellations of tickets by passengers and overbooking of planes by carriers. The simulation–optimization model developed here can be used to solve both single-leg problems and multi-leg or network problems. A model-free simulation–optimization approach only requires a discrete-event simulator of the system along with a numerical optimization method such as a gradient-ascent technique or a meta-heuristic. In this sense, it is relatively “easy” because alternative models such as dynamic programming or model-based gradient-ascent usually require more mathematically involved frameworks. Also, existing simulation-based approaches in the literature, unlike the one presented here, fail to capture the dynamics of cancellations and overbooking in their models. Empirical tests conducted with our approach demonstrate that it can produce robust solutions which provide revenue improvements over heuristics used in the industry, namely, EMSR (Expected Marginal Seat Revenue) for single-leg problems and DAVN (Displacement Adjusted Virtual Nesting) for networks.     

A mixed-integer simulation-based optimization approach with surrogate functions in water resources management

Efficient and powerful methods are needed to overcome the inherent difficulties in the numerical solution of many simulation-based engineering design problems. Typically, expensive simulation codes are included as black-box function generators; therefore, gradient information that is required by mathematical optimization methods is entirely unavailable. Furthermore, the simulation code may contain iterative or heuristic methods, low-order approximations of tabular data, or other numerical methods which contribute noise to the objective function. This further rules out the application of Newton-type or other gradient-based methods that use traditional finite difference approximations. In addition, if the optimization formulation includes integer variables the complexity grows even further. In this paper we consider three different modeling approaches for a mixed-integer nonlinear optimization problem taken from a set of water resources benchmarking problems. Within this context, we compare the performance of a genetic algorithm, the implicit filtering algorithm, and a branch-and-bound approach that uses sequential surrogate functions. We show that the surrogate approach can greatly improve computational efficiency while locating a comparable, sometimes better, design point than the other approaches.     

光学材料和光学薄膜的光热表征(英文)

光热技术用来测量样品的光学和热特性。简要介绍了光热技术及其在光学薄膜测量和钛蓝宝石激光晶体表征中的应用。光热技术可以提供纯光学光谱学所无法提供的、类似光-热能量转换效率之类的信息。光热技术已被用作质量测试和改善现代光学制造的有用工具。     

Effective visualisation of design versions: visual storytelling for design reuse

Improving and supporting the process of design knowledge reuse can increase productivity, improve the quality of designs and lead to corporate competitive advantage. Whereas internal knowledge reuse (reusing knowledge from one’s personal memory or experiences) is very effective, external knowledge reuse (reusing knowledge from an external digital or paper archive) often fails. This paper studies the value of the storytelling paradigm in supporting reuse from an external repository. Based on a formalisation of the internal reuse process from ethnographic studies, a prototype system, Corporate Memory (CoMem) is presented, which supports the reuse process, specifically the steps of finding and understanding reusable items. This paper focuses on the ability of designers to understand designs that are found in corporate repositories. It is argued that in order to understand and reuse a found design, the designer needs to see the evolution of that design during the original design process. An Evolution History Explorer module of the CoMem system is presented that uses a storytelling metaphor and lays out versions visually side-by-side. A formal user evaluation of CoMem supports the hypotheses that (1) exploring the evolution of a design improves the reuse process, and (2) that visual storytelling is an effective paradigm for supporting that exploration.     

Knowledge-based functional design of industrial robots

This paper presents an expert functional design model and software modeling environment for designing the architecture of industrial robots. The modeling environment comprises an integrated knowledge base, an inference engine, a working memory, and an explanation unit and is implemented in CLIPS. The functional design model is based on the authors’ behaviour-driven, function-environment-structure (B-FES) formalism, which has been tailored to meet the special requirements of industrial robot design. A universal robot template has been created and a library of typical components of a robot has been compiled. Nine customized templates were generated from the universal template. Web links to the websites of manufacturers/suppliers provide easy access to data on robot components. The architectural design solutions are assessed by a set of user-defined performance criteria, such as precision, flexibility and short cycle time. Application of the approach is demonstrated through a case study of the functional design of a printed circuit board assembly robot. The authors argue that this approach is new for configuring robots and can significantly reduce the time, effort and number of errors made.     

Ellipsometric characterisation of thin films non-uniform in thickness

Ellipsometric formulae for thin films non-uniform in thickness are presented. A general type of thickness non-uniformity is considered and the influence of the varying angle of incidence is taken into account. The presented formulae are applied to the optical characterisation of polymer SiO₂-like thin films exhibiting a relatively strong thickness non-uniformity. It is shown that the complete optical characterisation of these polymer thin films can be performed. Thus, the spectral dependences of the optical constants, mean thickness and parameters related to the shape of thickness non-uniformity can be determined.     

密码学中的布尔函数研究综述

概述了目前密码学中布尔函数的研究现状和重要研究方向上的新成果，并对布尔函数的研究进行了展望，指出了一些重要的研究热点问题．     

Comparison of analytical error and sampling error for contaminated soil

Investigation of soil from contaminated sites requires several sample handling steps that, most likely, will induce uncertainties in the sample. The theory of sampling describes seven sampling errors that can be calculated, estimated or discussed in order to get an idea of the size of the sampling uncertainties. With the aim of comparing the size of the analytical error to the total sampling error, these seven errors were applied, estimated and discussed, to a case study of a contaminated site. The manageable errors were summarized, showing a range of three orders of magnitudes between the examples. The comparisons show that the quotient between the total sampling error and the analytical error is larger than 20 in most calculation examples. Exceptions were samples taken in hot spots, where some components of the total sampling error get small and the analytical error gets large in comparison. Low concentration of contaminant, small extracted sample size and large particles in the sample contribute to the extent of uncertainty.     

Bending deformation and fracture characterisation in quenching and partitioning steel

The bending deformation recorded and fracture characterisation seen during the process of quenching and partitioning (Q&P) steel are investigated as a function of bending angle. According to experimental results, the mechanically induced martensitic transformation of the retained austenite occurred heterogeneously in the direction of thickness. Results from electron backscattered diffraction and finite element analysis confirmed that the heterogeneous phase transformation was caused by the stress difference in the direction of thickness. The results prove fracture behaviour is dominated by martensite cracking. The results provide a new insight into deformation characterisation of the Q&P steel under bending, which allows the design and optimisation of mechanical properties.     

工业设计中的知识管理

论述了建立面向工业设计的知识管理系统,对实现企业内、外部知识共享、知识应用和知识创新,保持设计师持续快速创新能力和企业新产品开发能力的重要作用,以及如何建立服务于工业设计的知识管理系统.     

Syntheses and characterisation of silver nanoparticles in the acrylate copolymers

Silver nanoparticles were synthesised by polyol method using copolymer templates under microwave heating. The copolymer templates were synthesised by reacting the synthesised macromonomers with comonomer using free radical polymerisation. The copolymers were characterised by Fourier Transform InfraRed, ¹H-NMR and ¹³C-NMR. The copolymers were further characterised by gel permeation chromatography for molecular weights and thermogravimetric analysis for thermal stability. These copolymers were used as nanoreactors in the syntheses of silver nanoparticles. The nanoparticles were characterised by various instrumental methods like UV-visible, FT-IR and High-resolution transmission electron microscopy to establish the average particle size and shape. Antibacterial activities of the copolymer-stabilised silver nanoparticles were tested on various microorganisms.     

粉末密度的测定方法及误差分析

本文详细介绍了使用比重瓶法测量粉末密度的方法并详细介绍了所需要的测量装置。对用比重瓶测量粉末密度的过程进行了详尽的阐述 ,给出了计算公式和推算过程以及最后的结论及测量的精度。最后 ,本文对粉末密度的测量结果进行了误差分析。