Building blocks towards VR-based flow sculpting

This paper reports work exploring the relationship between solid modelling, mesh generating and flow solving in the general context of design optimisation. In particular, the work is interested in the opportunities derived by tightly integrating these traditionally separate activities together within one piece of software. The near term aim is to ask the question: how might a truly virtual, rapid prototyping design system, with a tactile response like sculpting in clay, be constructed? This paper reports the building blocks supporting that ambition.

Viscous layer meshes from level sets on cartesian meshes

The long term goal of our work is to enable rapid prototyping design optimization to take place on geometries of arbitrary size in a spirit of a real time computer game. In recent papers we have reported the integration of a Level Set based geometry kernel with an octree-based cut-Cartesian mesh generator, RANS flow solver and post-processing all within a single piece of software - and all implemented in parallel with commodity PC clusters as the target. This work has shown that it is possible to eliminate all serial bottlenecks from the CED Process. This paper reports further progress towards our goal; in particular we report on the generation of viscous layer meshes to bridge the body to the flow across the cut-cells. The Level Set formulation, which underpins the geometry representation, is used as a natural mechanism to allow rapid construction of conformal layer meshes. The guiding principle is to construct the mesh which most closely approximates the body but remains solvable. This apparently novel approach is described and examples given.

The foundations of a new approach to additive manufacturing: Characteristics of free space metal deposition

In this paper, we report on the realisation of a free space deposition process (FSD). For the first time the use of a moving support structure to deposit tracks of metal starting from a substrate and extending into free space is characterised. The ability to write metal shapes in free space has wide ranging applications in additive manufacturing and rapid prototyping where the tracks can be layered to build overhanging features without the use of fixed support structures (such as is used in selective laser melting (SLM) and stereo lithography (SLA)). We demonstrate and perform a preliminary characterisation of the process in which a soldering iron was used to deposit lead free solder tracks. The factors affecting the stability of tracks and the effect of operating parameters, temperature, velocity, initial track starting diameter and starting volume were measured. A series of 10 tracks at each setting were compared with a control group of tracks; the track width, taper and variation between tracks were compared. Notable results in free space track deposition were that the initial track diameter and volume affected the repeatability and quality of tracks. The standard deviation of mean track width of tracks from the constrained initial diameter group were half that of the unconstrained group. The amount of material fed to the soldering iron before commencing deposition affected the taper of tracks. At an initial volume of 7 mm3 and an initial track diameter of 0.8 mm, none of the ten tracks deposited broke or showed taper > ∼1°. The maximum deposition velocity for free space track deposition using lead-free solder was limited to 1.5 mm s-1. © 2011 Elsevier B.V. All rights reserved.

Structural optimization of lattice materials

Lattice materials are characterized at the microscopic level by a regular pattern of voids confined by walls. Recent rapid prototyping techniques allow their manufacturing from a wide range of solid materials, ensuring high degrees of accuracy and limited costs. The microstructure of lattice material permits to obtain macroscopic properties and structural performance, such as very high stiffness to weight ratios, highly anisotropy, high specific energy dissipation capability and an extended elastic range, which cannot be attained by uniform materials. Among several applications, lattice materials are of special interest for the design of morphing structures, energy absorbing components and hard tissue scaffold for biomedical prostheses. Their macroscopic mechanical properties can be finely tuned by properly selecting the lattice topology and the material of the walls. Nevertheless, since the number of the design parameters involved is very high, and their correlation to the final macroscopic properties of the material is quite complex, reliable and robust multiscale mechanics analysis and design optimization tools are a necessary aid for their practical application. In this paper, the optimization of lattice materials parameters is illustrated with reference to the design of a bracket subjected to a point load. Given the geometric shape and the boundary conditions of the component, the parameters of four selected topologies have been optimized to concurrently maximize the component stiffness and minimize its mass. Copyright © 2011 by ASME.

面向快速成形的复杂曲面重建技术研究

针对快速成形工艺特点，提出了一种基于实物的复杂曲面几何重 建的方法。由此直接生成的快速成形机优化STL接口文件，实现了反求容差与模型网格数的 最佳匹配，避免了由通用软件转换存在的错误和繁复，提高了成形设备的前处理效率，并为 反求工程与快速成形技术的有机集成提供了可靠途径。

快速成型技术中分层算法的研究与进展

根据对零件制造精度和效率的关注程度的不同,开发出了多种分层算法。在同等加工时间的情况下,根据加工精度的不同,将这些分层算法分为等层厚分层算法和适应性分层算法两类。通过对STL模型、原始CAD模型和点云数据的分析,讨论了两类分层算法的研究和发展,然后介绍了斜边分层算法和曲面分层算法等先进分层算法的原理和成果,最后讨论了快速成型分层算法的研究方向和趋势。

激光金属沉积成形过程热行为的研究

激光金属直接快速成形技术是在80年代末期出现的快速原型技术（Rapid Phototyping, RP）基础上结合同步同轴送料激光熔敷（On-axis Laser Cladding）技术发展起来的一项先进制造技术。它涉及机械、激光、计算机辅助设计（CAD）、计算机辅助制造（CAM）、计算机数字控制（CNC）、材料科学等领域的关键技术。它突破了传统快速成形工艺方法和成形材料的局限，是目前快速成形诸多方法中研究最多、最有发展前途的新型制造技术。它基于材料累加思想，能够在无需任何刀具和模具的情况下由CAD模型直接驱动沉积成形金属零件，从而大大缩短了新产品的研发周期并节省了大量的资源。中国科学院沈阳自动化研究所开展了该技术的研究，并研制开发了激光金属沉积成形系统（Laser Metal Deposition Shaping, LMDS）。本文介绍了金属零件激光直接快速成形技术的原理和特点，分析了当前金属零件激光快速成形过程数值模拟研究的热点和发展趋势。结合激光金属沉积成形系统的研究需要和遇到的实际问题，阐述了激光、金属粉末和基板三者之间的相互作用，利用有限元的方法数值模拟了各种影响成形精度和效率的因素对激光金属沉积成形系统过程热行为的影响，包括不同扫描方式、不同基板预热温度等，并利用激光金属沉积成形系统系统进行了验证。具体的研究内容如下： 1. 阐述了激光与金属粉末之间的相互作用。激光快速成形过程中，高功率激光束与基板金属交互作用产生熔池，同步送入的金属粉末在熔池内被迅速熔化然后迅速凝固。熔池内的冶金动力学过程包括传热、传质、对流及气-液界面冶金反应和固-液界面扩散等与工艺质量的好坏密切相关，直接影响成形零件内气体和夹渣物的吸收、聚集和逸出，进而影响成形零件的微观组织、成分变化及其它物理冶金性能。基于熔池内传质、传热及流动对成形层的组织和性能的决定性作用，建立了激光金属沉积成形过程的数学模型和有限元模型。 2. 利用有限元分析中的“单元生死”技术，通过APDL语言编程建立了激光金属沉积成形系统过程三维多道多层的数值模拟模型，得到了激光金属沉积成形系统过程中试样和基板内的温度、温度梯度以及热应力分布规律。 3. 研究了沿长边平行往复扫描、沿短边平行往复扫描以及层间正交变向平行往复扫描等不同扫描方式对激光金属沉积成形系统过程热行为的影响，得到了不同扫描方式下试样和基板的温度、温度梯度和热应力变化规律，并结合快速凝固理论对这一过程中出现的现象进行解释。 4. 为了实现基板的预热，根据热传导理论自主设计开发了用于激光金属沉积成形系统过程的基板预热系统。该系统由基板预热器、智能PID控制器以及计算机串口温度检测和反馈控制等部分组成，具有结构简单、功能完善、可靠性高等特点。它既可以通过智能PID控制器实现对基板预热温度的控制，也可以通过计算机串口实现对基板预热温度的实时检测、记录以及反馈控制，从而使基板预热温度在室温～600℃之间连续调节。此外，它的计算机串口温度检测模块还可以用来实现对激光金属沉积成形系统成形过程基板温度的实时监测，为数值计算提供较为准确的边界条件以及用来检验和校正数值模型的正确性与可靠性。 5. 利用数值模拟的方法研究了基板预热温度分别在室温、200℃、300℃、400 ℃、500 ℃、600 ℃时对激光金属沉积成形系统过程温度、温度梯度以及热应力的影响。在相同的条件下，利用激光金属沉积成形系统系统和基板预热系统进行了实际成形实验。对成形实验得到的试样进行了深入的研究，包括：成形试样的成形高度和表面质量与基板预热温度的关系；成形试样的利用扫描电镜分析成形试件沉积层的显微组织特征；利用能谱仪分析沉积层合金元素的化学成分偏析情况。 6. 建立了集数值模拟和成形加工于一体的软件平台。它既可以实现简单零件变模型尺寸、变热物性参数和变工艺参数的数值模拟，也可以直接驱动激光金属沉积成形系统完成简单零件的快速成形。这为研究各工艺参数如激光功率、扫描速度、送粉速率、光斑尺寸以及基板预热温度等对激光金属沉积成形系统过程的影响提供了一个平台。

Keeping Secrets in Hardware: the Microsoft Xbox(TM) Case Study

This paper discusses the hardware foundations of the cryptosystem employed by the Xbox(TM) video game console from Microsoft. A secret boot block overlay is buried within a system ASIC. This secret boot block decrypts and verifies portions of an external FLASH-type ROM. The presence of the secret boot block is camouflaged by a decoy boot block in the external ROM. The code contained within the secret boot block is transferred to the CPU in the clear over a set of high-speed busses where it can be extracted using simple custom hardware. The paper concludes with recommendations for improving the Xbox security system. One lesson of this study is that the use of a high-performance bus alone is not a sufficient security measure, given the advent of inexpensive, fast rapid prototyping services and high-performance FPGAs.

In situ synthesis of DNA microarray on functionalized cyclic olefin copolymer substrate.

Thermoplastic materials such as cyclic-olefin copolymers (COC) provide a versatile and cost-effective alternative to the traditional glass or silicon substrate for rapid prototyping and industrial scale fabrication of microdevices. To extend the utility of COC as an effective microarray substrate, we developed a new method that enabled for the first time in situ synthesis of DNA oligonucleotide microarrays on the COC substrate. To achieve high-quality DNA synthesis, a SiO(2) thin film array was prepatterned on the inert and hydrophobic COC surface using RF sputtering technique. The subsequent in situ DNA synthesis was confined to the surface of the prepatterned hydrophilic SiO(2) thin film features by precision delivery of the phosphoramidite chemistry using an inkjet DNA synthesizer. The in situ SiO(2)-COC DNA microarray demonstrated superior quality and stability in hybridization assays and thermal cycling reactions. Furthermore, we demonstrate that pools of high-quality mixed-oligos could be cleaved off the SiO(2)-COC microarrays and used directly for construction of DNA origami nanostructures. It is believed that this method will not only enable synthesis of high-quality and low-cost COC DNA microarrays but also provide a basis for further development of integrated microfluidics microarrays for a broad range of bioanalytical and biofabrication applications.

Direct measurement of powder flavor adhesion onto crisp surface using a novel adhesion tester

A new experimental procedure has been implemented and a prototype of a novel adhesion tester has been designed and constructed using rapid prototyping technology. A tumbler mixer has been designed and constructed for coating powder material onto a crisp substrate. In the impact separation experiment, the amount of powder detached from one side of a crisp substrate by the effect of impact forces (48g, 77g, 102g) generated by the tester was measured. Salt particles with different size fractions (63-125, 125-180, and 180-250m) and several flavoring powders have been tested extensively. By plotting the detachment versus impact force, the difference obtained between adhesion strength of different flavoring powders (which is a strong function of particle size and surface oil content of the crisp) has been discussed. The detachment rate of salt particles increased (from 1% to 2%) with particle size (from 63 to 250m) in the presence of oil on the surface of the crisp substrate and decreased rapidly with the increase in the amount of oil applied (from 0 to 1%).

Creating replicas of scultural heritage through 3D reconstruction and low cost 3D printer in Education

The process of making replicas of heritage has traditionally been developed by public agencies, corporations and museums and is not commonly used in schools. Currently there are technologies that allow creating cheap replicas. The new 3D reconstruction software, based on photographs and low cost 3D printers allow to make replicas at a cost much lower than traditional. This article describes the process of creating replicas of the sculpture Goslar Warrior of artist Henry Moore, located in Santa Cruz de Tenerife. To make this process, first, a digital model have been created using Autodesk Recap 360, Autodesk 123D Catch and Autodesk Meshmixer MarkerBot MakerWare applications. Physical replication, has been reproduced in polylactic acid (PLA) by MakerBot Replicator 2 3D printer. In addition, a cost analysis using, in one hand, the printer mentioned, and in the other hand, 3D printing services both online and local, is included. Finally, there has been a specific action with 141 students and 12 high school teachers, who filled a questionnary about the use of sculptural replicas in education.

Design e desenvolvimento de equipamentos de iluminação técnica

Este documento é uma sinopse das atividades desenvolvidas e, conhecimentos adquiridos ao longo do estágio na empresa Lightenjin, Sistemas de Iluminação, Lda. e, surge em forma de relatório de projeto. O primeiro projeto foi o desenvolvimento de uma família de candeeiros. O segundo e principal projeto foi a criação e desenvolvimento de um projetor para aplicação em calha eletrificada, com as devidas restrições do Project brief apresentado pela empresa. O terceiro projeto foi o desenvolvimento de um projetor Downlight de encastrar. Houve outras tarefas ligadas à modelação de componentes, desenhos técnicos, manuais de instruções, fichas técnicas e prototipagem rápida. Em todos os projetos foi utilizada a metodologia de trabalho apresentada.

I Cling to Virtue

Kular’s work centres on design as a means of engaging with social and cultural issues. Commissioned and exhibited by the V&A Museum, this was a mixed-media collection revealing the trajectories of the Lövy-Singh clan, a fictional East London family of mixed descent. It comprised 26 sculptures and two video pieces, developing the previous explorations of the MacGuffin in narrative (Kular REF Output 2). A catalogue with 28 fictional reminiscences, a genealogy and time line positioned the family’s experiences in geographical locations and historical events. Novel use of rapid-prototyping co-opted an industry process to confuse the experience of artefact and artifice. The design explored the historical, literary and cinematic traditions of the family saga and its relationship to memory and artefact. It presented an archive of objects derived from the flawed, biased memory of the (fictional) curator. A coherent story is replaced by one that is multiple and fragmentary. Kular and Toran (RCA) ‘produced’ the family by mixing their own genealogies with those of renowned 20th-century families, both real and fictional, such as the Magnificent Ambersons and the Rothschilds, positioning family members in everyday situations or key historical moments represented by an object and a ‘memory’ triggered by the object. Concept development was undertaken jointly by Kular and Toran. Kular’s archive research emphasised commonwealth immigrant histories and British 20th-century political events. His production contribution was in 3D modelling, rapid prototyping and display, leading production of the two films and development and editing of the narrative texts. The work was accompanied by a catalogue (2011), was reviewed in ICON Magazine (2010), discussed in an article by Hayward, Jones, Toran and Kular in Design and Culture (2013), and featured in The White Review (No. 2). It was re-exhibited in the group show ‘Politique Fiction’ at la Cité du design, Saint-Étienne, France (2013).

A biosignal embedded system for physiological computing

Thesis submitted in the fulfilment of the requirements for the Degree of Master in Electronic and Telecomunications Engineering

Benefits & drawbacks of different means of interaction for placing objects above a video footage

Public Display Systems (PDS) increasingly have a greater presence in our cities. These systems provide information and advertising specifically tailored to audiences in spaces such as airports, train stations, and shopping centers. A large number of public displays are also being deployed for entertainment reasons. Sometimes designing and prototyping PDS come to be a laborious, complex and a costly task. This dissertation focuses on the design and evaluation of PDS at early development phases with the aim of facilitating low-effort, rapid design and the evaluation of interactive PDS. This study focuses on the IPED Toolkit. This tool proposes the design, prototype, and evaluation of public display systems, replicating real-world scenes in the lab. This research aims at identifying benefits and drawbacks on the use of different means to place overlays/virtual displays above a panoramic video footage, recorded at real-world locations. The means of interaction studied in this work are on the one hand the keyboard and mouse, and on the other hand the tablet with two different techniques of use. To carry out this study, an android application has been developed whose function is to allow users to interact with the IPED Toolkit using the tablet. Additionally, the toolkit has been modified and adapted to tablets by using different web technologies. Finally the users study makes a comparison about the different means of interaction.