• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 27
  • 20
  • 8
  • 7
  • 5
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 81
  • 81
  • 43
  • 39
  • 31
  • 15
  • 12
  • 10
  • 10
  • 10
  • 9
  • 9
  • 8
  • 7
  • 7
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Analysis and design of virtual enterprises

Pego-Guerra, Marco Antonio 01 May 2006 (has links)
Virtual Enterprise (VE) is an organizational business concept. Its key ingredients are collaboration among a set of member companies and integration of their competencies, which are needed for developing a new product or service. This concept is in response to the ever-increasing demand on the manufacturing enterprise to react quickly to changes in the market conditions and become agile enterprises. This thesis presents a quantitative study on the life cycle of Virtual Enterprises. Specifically, it covers the design and management phases. These two phases are modeled using system engineering as a foundation. This has led to the development of two new methods for designing and managing Virtual Enterprises. The design method uses Axiomatic Design Theory and a methodology for complex large systems. The management method is based on the Robust Design principles.
22

Holistic biomimicry: a biologically inspired approach to environmentally benign engineering

Reap, John J. 13 November 2009 (has links)
Humanity's activities increasingly threaten Earth's richness of life, of which mankind is a part. As part of the response, the environmentally conscious attempt to engineer products, processes and systems that interact harmoniously with the living world. Current environmental design guidance draws upon a wealth of experiences with the products of engineering that damaged humanity's environment. Efforts to create such guidelines inductively attempt to tease right action from examination of past mistakes. Unfortunately, avoidance of past errors cannot guarantee environmentally sustainable designs in the future. One needs to examine and understand an example of an environmentally sustainable, complex, multi-scale system to engineer designs with similar characteristics. This dissertation benchmarks and evaluates the efficacy of guidance from one such environmentally sustainable system resting at humanity's doorstep - the biosphere. Taking a holistic view of biomimicry, emulation of and inspiration by life, this work extracts overarching principles of life from academic life science literature using a sociological technique known as constant comparative method. It translates these principles into bio-inspired sustainable engineering guidelines. During this process, it identifies physically rooted measures and metrics that link guidelines to engineering applications. Qualitative validation for principles and guidelines takes the form of review by biology experts and comparison with existing environmentally benign design and manufacturing guidelines. Three select bio-inspired guidelines at three different organizational scales of engineering interest are quantitatively validated. Physical experiments with self-cleaning surfaces quantify the potential environmental benefits generated by applying the first, sub-product scale guideline. An interpretation of a metabolically rooted guideline applied at the product / organism organizational scale is shown to correlate with existing environmental metrics and predict a sustainability threshold. Finally, design of a carpet recycling network illustrates the quantitative environmental benefits one reaps by applying the third, multi-facility scale bio-inspired sustainability guideline. Taken as a whole, this work contributes (1) a set of biologically inspired sustainability principles for engineering, (2) a translation of these principles into measures applicable to design, (3) examples demonstrating a new, holistic form of biomimicry and (4) a deductive, novel approach to environmentally benign engineering. Life, the collection of processes that tamed and maintained themselves on planet Earth's once hostile surface, long ago confronted and solved the fundamental problems facing all organisms. Through this work, it is hoped that humanity has taken one small step toward self-mastery, thus drawing closer to a solution to the latest problem facing all organisms.
23

Design-for-manufacturability (DFM) for system-in-package (SiP) applications

Doppalapudi, Ranjeeth 19 November 2008 (has links)
Microelectronic systems packaging involves layout dimensions of the order of microns. During manufacturing, process variations will cause parameters to deviate from their nominal values. As a result, the manufactured circuit may no longer meet the specifications it is designed to satisfy. When producing high volume of electronics, assembly yield becomes very important. This is where tolerance margins of the design parameters play an important role. This means that the performance specifications should be satisfied if the process variations are within the given tolerance margin of design parameters. Research has been done on circuit level design for manufacturability methods. The main objective of the research is to study the layout level DFM methods for signal integrity issues and embedded Rf passive components and use design centering methodology to improve the output yield value. In this dissertation, emphasis is also laid on taking care of the regression error while calculating the yield value. With the developed method, the number of design iteration cycles to maximize yield is significantly reduced.
24

Development of Soft Actuation Systems for Use in Human-Centered Applications

Wirekoh, Jackson O. 01 December 2017 (has links)
In recent years, soft materials have seen increased prevalence in the design of robotic systems and wearables capable of addressing the needs of individuals living with disabilities. In particular, pneumatic artificial muscles (PAMs) have readily been employed in place of electromagnetic actuators due to their ability to produce large forces and motions, while still remaining lightweight, compact, and flexible. Due to the inherent nonlinearity of PAMs however, additional external or embedded sensors must be utilized in order to effectively control the overall system. In the case of external sensors, the bulkiness of the overall system is increased, which places limits on the system’s design. Meanwhile, the traditional cylindrical form factor of PAMs limits their ability to remain compact and results in overly complex fabrication processes when embedded fibers and/or sensing elements are required to provide efficient actuation and control. In order to overcome these limitations, this thesis proposed the design of flat pneumatic artificial muscles (FPAMs) capable of being fabricated using a simple layered manufacturing process, in which water-soluble masks were utilized to create collapsed air chambers. Furthermore, hyperelastic deformation models were developed to approximate the mechanical performance of the FPAMs and were verified through experimental characterization. The feasibility of these design techniques to meet the requirements of human centered applications, including the suppression of hand tremors and catheter ablation procedures, was explored and the potential for these soft actuation systems to act as solutions in other real world applications was demonstrated. We expect the design, fabrication, and modeling techniques developed in this thesis to aid in the development of future wearable devices and motivate new methods for researchers to employ soft pneumatic systems as solutions in human-centered applications.
25

Design klimatizační jednotky pro aditivní robotickou výrobu / Design of the Air conditioning unit for additive robotic fabrication

Mandáková, Adéla January 2021 (has links)
The design of air conditioning unit is based on combination of the product itself and related architecture. The large-scale 3D printing is becoming more and more popular, that is why this thesis chose additive manufacturing robotic technology for designing the air conditioner. According to analysis the air distribution through perforations is the most convenient one for an indoor unit. An outdoor unit tends to be hidden because of inhomogeneity with the building. To obtain more variant studies for the design a generative process was applied. This method was applied also later on, because additive manufacturing is able to easily change dimension parameters and thus fulfil individual customer requests. Other advantages of robotic printing are the lattice structures that enable perforation manufacturing without waste and the possibility of using generative design methods.
26

Concept Development of a Recliner Mechanism for a Car Seat

Mora Fontelles, Alejandro January 2016 (has links)
Nowadays, there are more and more regulations regarding the emissions of greenhouse gases. The automotive sector is directly affected by new standards enacted by the National Highway Traffic Safety Administration (NHTSA) in America and by European regulations in Europe that are forcing car manufacturers to produce more efficient cars. Different ways exist to increase the efficiency of a car and thus reduce the CO2 emissions. One known strategy to improve fuel economy in vehicles is by weight reduction. Consequently, car manufacturers are seeking out new companies that can supply them with lighter car components. Here is where VA Automotive enters the picture, as a car seat manufacturer that is willing to improve their product by reducing the weight of its various components. This study deals with the development of a new recliner design that demonstrates improvements in terms of weight, size and performance compared to the current solution used at VA Automotive. A common product development methodology has been developed to reach the final recliner design which went through the following steps. First of all, a benchmarking technique was adopted to gather as much data as possible from the competitors’ products. Then, a list of target values for the product specifications was defined as a guideline for the development of the product. The next step was to generate several concepts of recliner’s mechanism that were suitable to improve the design from VA Automotive. After that, a Pugh decision matrix was used to select the best alternative between the concepts generated previously. The optimal concept was further developed by generating four design alternatives that were analyzed in terms of manufacturing, assembly, weight and size by using the Lucas DFMA method. Finally some simulations were run for one of the designs in order to check the structural performance of the mechanism and prove this way that the new recliner design meets the requirements. When comparing the new design alternatives with the design from VA Automotive, it was noticed that all the new designs except one presented a lower manufacturing cost index. Moreover, for all of the alternatives of the new recliner design, the weight was reduced by more than 56% compared to the recliner used at VA Automotive. Finally, by means of FEM simulations it was demonstrated that by choosing the right material the new recliner design was able to meet the structural requirements.
27

Wheel Loader Rear Axle Mounting for Weld Deformations : Exploration and Evaluation of Alternative Mounting Methods

Forsberg, Frans January 2023 (has links)
Welded structures susceptible to weld deformations require sequent processing to allow for mounting of precision components. This thesis includes a case study of the rear axle mount on a Volvo L220 wheel loader. A product development process was deployed in order to explore and evaluate alternative mounting methods such that manufacturing cost due to sequent processing could be decreased. Analysis of the frame variations showed any new concepts has to accommodate variations of up to $\delta z=-1.24\pm3.5$ mm. The product development process found two potential concept philosophies; transferring concepts which improves upon the current concept by transferring the processing away from the frame onto smaller components that are cheaper to process, and absorbing concepts that avoids sequent processing by absorbing the frame variations altogether. The transferring concept "Custom Plate" was selected for further development. The concept is based on the principals of reverse engineering by manufacturing a custom plate from a 3D surface map of the deformed mounting surface, placed between the frame and rear axle bridge, matching the surface geometry of both entities. The concept showed no apparent critical strength issues when simulated in CATIA V5. However, the economical gain of the concept is slim and depends heavily what spaces can be allocated for additional processing machinery. Suggestions for further development of the concept are given along with a discussion of improvements outside of the system boundary of the project, such as simulation of welds and welding sequence, and collection, storing, analysis, and visualisation of data.
28

Fume Cover Flash Chromatography system : The design of a Fume Cover

Horn, Alexander, Schenk, Hannes January 2023 (has links)
In laboratory work and working with Biotage’s Selekt Enkel chromatography system, it is common that operators are exposed to harmful and bad-smelling solvents gases. These are common issues that Biotage wants the students to solve. For this thesis work, the mission and task is to propose the best possible design of a Fume Cover that can remove or at least reduce those certain issues. To understand and gain the necessary knowledge, different data-gathering methods like workshops with staff and an extensive literature study of solvents and materials helped to establish a good design framework. Three concepts were built as 3D – models. The concept of Pugh’s iterative improvement method was used to produce an even better concept than the previous three. The chosen concept was iteratively improved for manufacturing and tested in an airflow experiment with carbon dioxide ice determining the optimal design. The conclusion is that it is possible to design a fume cover to reduce the solvent gas exposure, but further testing with light solvent gases and redesign will be required.
29

Geometric Complexity based Process Selection and Redesign for Hybrid Additive Manufacturing

Joshi, Anay January 2017 (has links)
No description available.
30

A SHEET METAL DESIGN ADVISOR: DESIGN RULES AND INTER-FEATURE DESIGN CHECKING

HEGDE, SHASHIKIRAN RAGHUPATI 02 September 2003 (has links)
No description available.

Page generated in 0.0652 seconds