Determination of beam incidence conditions based on the analysis of laser interference patterns

Beam incidence conditions in the formation of two-, three- and four-beam laser interference patterns are presented and studied in this paper. In a laser interference lithography (LIL) process, it is of importance to determine and control beam incidence conditions based on the analysis of laser interference patterns for system calibration as any slight change of incident angles or intensities of beams will introduce significant variations of periods and contrasts of interference patterns. In this work, interference patterns were captured by a He-Ne laser interference system under different incidence conditions, the pattern period measurement was achieved by cross-correlation with, and the pattern contrast was calculated by image processing. Subsequently, the incident angles and intensities of beams were determined based on the analysis of spatial distributions of interfering beams. As a consequence, the relationship between the beam incidence conditions and interference patterns is revealed. The proposed method is useful for the calibration of LIL processes and for reverse engineering applications

Teaching Design Patterns Using Interactive Methods

Even though design patterns are one of the most important building blocks in the current software engineering ecosystem, computer science and software engineering graduates face trouble applying these patterns. To address this, we propose a tutorial and an online lab assessment method to solidify the idea of design patterns for students. The tutorial part integrates a live coding session. The online lab assessment consists of a three-stage process (designing a solution using a class diagram, peer review, and implementation) where students are expected to come up with a fully working solution using design patterns. The proposed approach is applied twice over two semesters to a total sum of 196 students. We discuss the effects of these interactive educational methods on learning by comparing pre-surveys, post-surveys and analyzing final grades. The analysis of the surveys shows that live coding is highly beneficial in enhancing the understanding of design patterns

High-throughput three-dimensional lithographic microfabrication

A 3D lithographic microfabrication process has been developed that is high throughput, scalable, and capable of producing arbitrary patterns. It offers the possibility for industrial scale manufacturing of 3D microdevices such as photonic crystals, tissue engineering scaffolds, and microfluidics chips. This method is based on depth-resolved wide-field illumination by temporally focusing femtosecond light pulses. We characterized the axial resolution of this technique, and the result is consistent with the theoretical prediction. As proof-of-concept experiments, we demonstrated photobleaching of 3D resolved patterns in a fluorescent medium and fabricating 3D microstructures with SU-8 photoresist.Deshpande Center for Technological Innovation (Massachusetts Institute of Technology. School of Engineering)Singapore-MIT Alliance for Research and Technology (SMART

Approach for model-based requirements engineering for the planning of engineering generations in the agile development of mechatronic systems

The crucial factor for a successful usage of modeling approaches of systems engineering is the interaction of language, method, and tool. For this, specific challenges arise for the application of MBSE in agile requirements engineering. From observations in agile development practice at a machine tool manufacturer, the challenges for model-based requirements engineering are described and each is assigned to its critical aspect of modeling: The language must formally represent the requirements data model, especially for planning engineering generations. The tool must support collaborative, interdisciplinary cooperation, and consider the dynamics of the requirements model during the development process. The method must individually support the requirements engineering activities, which are carried out several times in a sprint during the development process and must enable a target-oriented process for bundling the requirements into engineering generations. Taking these demands into account, an approach is then presented providing activity-based views in conjunction with activity steps based on a consistent ontology for the description of product requirements and verification activities. The activity steps are composed in activity patterns and support the user in making use of the views for modeling requirements for the engineering generations. The approach is implemented in the software JIRA at a machine tool manufacturer. The subsequent evaluation shows that the approach is used in development practice and offers the potential to plan engineering generation systematically and comprehensibly and to ensure a regular review of the implemented requirements

Case-based analysis in user requirements modelling for knowledge construction

Context: Learning can be regarded as knowledge construction in which prior knowledge and experience serve as basis for the learners to expand their knowledge base. Such a process of knowledge construction has to take place continuously in order to enhance the learners’ competence in a competitive working environment. As the information consumers, the individual users demand personalised information provision which meets their own specific purposes, goals, and expectations. Objectives: The current methods in requirements engineering are capable of modelling the common user’s behaviour in the domain of knowledge construction. The users’ requirements can be represented as a case in the defined structure which can be reasoned to enable the requirements analysis. Such analysis needs to be enhanced so that personalised information provision can be tackled and modelled. However, there is a lack of suitable modelling methods to achieve this end. This paper presents a new ontological method for capturing individual user’s requirements and transforming the requirements onto personalised information provision specifications. Hence the right information can be provided to the right user for the right purpose. Method: An experiment was conducted based on the qualitative method. A medium size of group of users participated to validate the method and its techniques, i.e. articulates, maps, configures, and learning content. The results were used as the feedback for the improvement. Result: The research work has produced an ontology model with a set of techniques which support the functions for profiling user’s requirements, reasoning requirements patterns, generating workflow from norms, and formulating information provision specifications. Conclusion: The current requirements engineering approaches provide the methodical capability for developing solutions. Our research outcome, i.e. the ontology model with the techniques, can further enhance the RE approaches for modelling the individual user’s needs and discovering the user’s requirements

A Study on Reuse-based Requirements Engineering by Utilizing Knowledge Pattern

Software development has become an essential part of many industries over the past decade. The use of software has become an essential element for the organization to support its operation and business. Some software has certain features in common, which allow its requirements to be used repetitively in the requirement engineering phase. This paper presents a study on knowledge patterns for reuse-based requirements engineering. Reuse-based requirements engineering is saving the effort to conduct the process and, at the same time maintaining the standard since reused requirements come with its properties as well.  Software development is an iterative process itself and so does the knowledge it holds in every iteration. When analysts perform many iterations of elicitation processes, it is often the case that a significant amount of requirements is recurring and similar software system will likely benefit from them. This research adopted a literature review method to investigate and to present current studies on knowledge pattern for the purpose of reuse. Knowledge reuse by utilizing knowledge pattern is becoming a significant method in software requirements engineering as it safes the effort of developing requirements from scratch. The study found that a specific pattern is required to develop good requirements specification. A proposed prototype to deploy reuse-based requirements engineering is also presented and evaluated. Experts’ judgment method is used for evaluation by adapting the Technology Acceptance Model (TAM). The results showed that reusing knowledge pattern expedites the requirements elicitation process and improves the requirements quality.