Curing Temperature Study for Curl Distortion Control and Simulation in Projection Based Stereolithography

2014 ◽  
Author(s):  
Kai Xu ◽  
Yong Chen
Keyword(s):  
High Resolution ◽  
Curing Temperature ◽  
Test Case ◽  
Ir Camera ◽  
Temperature Study ◽  
Distortion Control ◽  
Curl Distortion ◽  
Major Factors ◽  
Thermal Cooling ◽  
Case Based

Polymerization shrinkage and thermal cooling effect have been identified as two major factors leading to the curl distortion in the Stereolithography (SLA) process. In this paper, the curing temperatures of built layers in the mask image projection based Stereolithography (MIP-SL) process are investigated using a high-resolution infrared (IR) camera. The curing temperatures of built layers using different exposure strategies including varying exposure time, grayscale levels and mask image patterns have been studied. The curl distortions of a test case based on various exposure strategies have been measured and analyzed. It is shown that, by decreasing the curing temperature of built layers, the exposure strategies using grayscale levels and mask image patterns can effectively reduce the curl distortion. In addition to curl distortion control, the curing temperature study also provides a basis for the curl distortion simulation in the MIP-SL process.

Photocuring Temperature Study for Curl Distortion Control in Projection-Based Stereolithography

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Kai Xu ◽  
Yong Chen
Keyword(s):  
Test Case ◽  
Test Cases ◽  
Ir Camera ◽  
Temperature Study ◽  
Building Process ◽  
Distortion Control ◽  
Curl Distortion ◽  
Different Shapes ◽  
Major Factors ◽  
Thermal Cooling

Polymerization shrinkage and thermal cooling effect have been identified as two major factors that lead to the curl distortion in the stereolithography apparatus (SLA) process. In this paper, the photocuring temperature during the building process of mask image projection-based stereolithography (MIP-SL) and how it affects parts' curl distortion are investigated using a high-resolution infrared (IR) camera. Test cases of photocuring layers with different shapes, sizes, and layer thicknesses have been designed and tested. The experimental results reveal that the temperature increase of a cured layer is mainly related to the layer thickness, while the layer shapes and sizes have little effect. The photocuring temperatures of built layers using different exposure strategies including varying exposure time, grayscale levels, and mask image patterns have been studied. The curl distortions of a test case based on various exposure strategies have been measured and analyzed. It is shown that, by decreasing the photocuring temperature of built layers, the exposure strategies using grayscale levels and mask image patterns can effectively reduce the curl distortion with the expense of increased building time. In addition to curl distortion control, the photocuring temperature study also provides a basis for the curl distortion simulation in the MIP-SL process.

Deformation Control Based on In-Situ Sensors for Mask Projection Based Stereolithography

2014 ◽  
Author(s):  
Kai Xu ◽  
Yong Chen
Keyword(s):  
Temperature Increase ◽  
Computer Aided Design ◽  
Test Case ◽  
Element Analysis ◽  
Ir Camera ◽  
Deformation Control ◽  
Fea Model ◽  
Building Process ◽  
Curl Distortion

Curl distortion is one of the main reasons for the part inaccuracy in the Mask Image Projection based Stereolithography (MIP-SL) process. During the building process, the photopolymerization of liquid resin leads to temperature increase. After cooling down, the cured layers will shrink while they are constrained by its supports or the previously built layers. Consequently, residue stresses exist in the built part and will lead to curl distortion after all the supports are removed. In this paper, we investigate the thermal effect in the building process by using an infrared (IR) camera as an in-situ temperature monitoring sensor. Test cases of cured layers with different shapes, sizes and layer thicknesses have been designed and tested. The experimental results show that the temperature increase of a cured layer is mainly related to its layer thickness, while its shapes and sizes have less effect. The temperature increase of a cured layer is also related to its building position in the Z axis. The calibrated temperature increases in the MIP-SL process can be incorporated in a Finite Element Analysis (FEA) model in order to simulate the curl distortion of a given computer-aided design model. Physical experiments of a simple test case have been built, measured, and compared with the FEA simulation result. A discussion of the curl distortion in the MIP-SL process including its prediction and compensation is given.

High-Resolution Scanning Electron Microscopy of Biological Specimens

1988 ◽  
Vol 46 ◽  
pp. 186-187
Author(s):  
M. Müller ◽  
R. Hermann
Keyword(s):  
High Resolution ◽  
Freeze Drying ◽  
Room Temperature ◽  
Structural Information ◽  
Freeze Substitution ◽  
Critical Point Drying ◽  
Sem Study ◽  
Major Factors ◽  
Structural Preservation ◽  
Preparation Techniques

Three major factors must be concomitantly assessed in order to extract relevant structural information from the surface of biological material at high resolution (2-3nm).Procedures based on chemical fixation and dehydration in graded solvent series seem inappropriate when aiming for TEM-like resolution. Cells inevitably shrink up to 30-70% of their initial volume during gehydration; important surface components e.g. glycoproteins may be lost. These problems may be circumvented by preparation techniques based on cryofixation. Freezedrying and freeze-substitution followed by critical point drying yields improved structural preservation in TEM. An appropriate preservation of dimensional integrity may be achieved by freeze-drying at - 85° C. The sample shrinks and may partially collapse as it is warmed to room temperature for subsequent SEM study. Observations at low temperatures are therefore a necessary prerequisite for high fidelity SEM. Compromises however have been unavoidable up until now. Aldehyde prefixation is frequently needed prior to freeze drying, rendering the sample resistant to treatment with distilled water.

scholarly journals Potentialities and Limitations of Research on VHRS Data: Alexander the Great’s Military Camp at Gaugamela on the Navkur Plain in Kurdish Iraq as a Test Case

2021 ◽  
Vol 13 (5) ◽  
pp. 904
Author(s):  
Tomasz Pirowski ◽  
Michał Marciak ◽  
Marcin Sobiech
Keyword(s):  
Image Processing ◽  
High Resolution ◽  
Vegetation Indices ◽  
Test Case ◽  
Linear Features ◽  
Negative Results ◽  
Research Perspectives ◽  
Military Camp ◽  
Different Color ◽  
Very High

This paper presents a selected aspect of research conducted within the Gaugamela Project, which seeks to finally identify the location of one of the most important ancient battles: the Battle of Gaugamela (331 BCE). The aim of this study was to discover material remains of the Macedonian military camp on the Navkur Plain in Kurdish Iraq. For this purpose, three very high resolution satellite (VHRS) datasets from Pleiades and WorldView-2 were acquired and subjected to multi-variant image processing (development of different color composites, integration of multispectral and panchromatic images, use of principle component analysis transformation, use of vegetation indices). Documentation of photointerpretation was carried out through the vectorization of features/areas. Due to the character of the sought-after artifacts (remnants of a large enclosure), features were categorized into two types: linear features and areal features. As a result, 19 linear features and 2 areal features were found in the study area of the Mahad hills. However, only a few features fulfilled the expected geometric criteria (layout and size) and were subjected to field groundtruthing, which ended in negative results. It is concluded that no traces have been found that could be interpreted as remnants of an earthen enclosure capable of accommodating around 47,000 soldiers. Further research perspectives are also suggested.

Unmanned Aerial Vehicle (UAV) time-lapse monitoring of the instability processes affecting Varano Hill: A case study of the ancient Roman site of Villa Arianna

2021 ◽  
Author(s):  
Renato Somma ◽  
Alfredo Trocciola ◽  
Daniele Spizzichino ◽  
Alessandro Fedele ◽  
Gabriele Leoni ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Data ◽  
Morphological Evolution ◽  
Archaeological Site ◽  
Pilot Project ◽  
Time Lapse ◽  
3D Models ◽  
Slope Instability ◽  
Test Case ◽  
Slope Instabilities

<p>The archaeological site of Villa Arianna - located on Varano Hill, south of Vesuvius - offer tantalizing information regarding first-century AD resilience to hydrogeological risk. Additionally, the site provides an important test case for mitigation efforts of current and future geo-hazard. Villa Arianna, notable in particular for its wall frescoes, is part of a complex of Roman villas built between 89 BC and AD 79 in the ancient coastal resort area of Stabiae. This villa complex is located on a morphological terrace that separates the ruins from the present-day urban center of Castellammare di Stabia. The Varano hill is formed of alternating pyroclastic deposits, from the Vesuvius Complex, and alluvial sediments, from the Sarno River. The area, in AD 79, was completely covered by PDCs from the Plinian eruption of Vesuvius. Due to the geomorphological structure the slope is prone to slope instability phenomena that are mainly represented by earth and debris flows, usually triggered by heavy rainfall. The susceptibility is worsened by changes in hydraulic and land-use conditions mainly caused by lack of maintenance of mitigation works. Villa Arianna is the subject of a joint pilot project of the INGV-ENEA-ISPRA that includes non-invasive monitoring techniques such as the use of UAVs to study the areas of the slope at higher risk of instability. The project, in particular, seeks to implement innovative mitigation solutions that are non-destructive to the cultural heritage. UAVs represent the fastest way to produce high-resolution 3D models of large sites and allow archaeologists to collect accurate spatial data that can be used for 3D GIS analyses. Through this pilot project, we have used detailed 3D models and high-resolution ortho-images for new analyses and documentation of the site and to map the slope instabilities that threatens the Villa Arianna site. Through multi-temporal analyses of different data acquisitions, we intend to define the detailed morphological evolution of the entire Varano slope. These analyses will allow us to highlight priority areas for future low-impact mitigation interventions.</p>

Methods for Process Selection in Design

1990 ◽  
Author(s):  
K. Ishii ◽  
C. H. Lee ◽  
R. A. Miller
Keyword(s):  
Life Cycle Cost ◽  
Object Oriented ◽  
Manufacturing Processes ◽  
Future Challenge ◽  
Process Selection ◽  
Development Environment ◽  
Types Of Knowledge ◽  
Major Factors ◽  
Case Based ◽  
Selection Of

Abstract This paper describes our proposed methodology for process selection that applies to the early stages of product design. We focus on net-shape manufacturing processes and identify the major factors that affect the selection of an appropriate process. The sequence at which designers typically make decisions depends largely on the nature of the product and the development environment. Thus, a versatile methodology should consider all the factors simultaneously in assessing the suitability of the candidate processes. The paper describes three types of knowledge that represent the compatibility of various processes to a given set of specifications: a) Case-based knowledge, i.e., templates of good, bad, and poor combination of decisions, b) Ordinal relationships among candidate processes based on interval analysis of cost, and c) Life-cycle cost estimate. Each type of knowledge gives an evaluation of suitability (compatibility) of candidate processes. Our future challenge lies in combining these measures at various stages of product development. Our initial studies on relationships between process selection and influencing factors lead to a HyperCard stack which stores information in an object-oriented fashion. This stack contains information which is the basis for our future computer-aid for process selection.

Integrating Big Data Technology Into Organizational Decision Support Systems

2021 ◽  
pp. 639-657
Author(s):  
Ahmad M. Kabil
Keyword(s):  
Big Data ◽  
Decision Support ◽  
Conceptual Design ◽  
Support Systems ◽  
Test Case ◽  
Detailed Design ◽  
Global Competitiveness ◽  
Design And Implementation ◽  
Business Complexity ◽  
Case Based

With the growing trend of global competitiveness and business complexity, the need arises for integrating BDTs in the design of ODSS. BDTs enable ODSS to deal with data of volume, variety, and velocity beyond the capability of traditional databases and data-warehouses in ODSS. The basic modules of updated ODSS with BDT are presented as a conceptual design, which provides a general foundation for the detailed design and implementation of an application. The validation of the proposed conceptual design is conducted on a test-case based upon the BSC perspectives as well as requirements common for ODSS scenarios. The results show that each requirement of the system is supported by a set of integrated modules in a balanced way. The modules of the highest contribution in the conceptual design are the modules most related to BDT. The initial stages of the implementation of the system are given.

Deep Near-Infrared Surveys and Young Brown Dwarf Populations in Star-Forming Regions

2003 ◽  
Vol 211 ◽  
pp. 87-90
Author(s):  
M. Tamura ◽  
T. Naoi ◽  
Y. Oasa ◽  
Y. Nakajima ◽  
C. Nagashima ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Brown Dwarf ◽  
Ir Camera ◽  
Star Forming ◽  
Star Forming Regions ◽  
New Instrument ◽  
Infrared Surveys ◽  
Low Mass

We are currently conducting three kinds of IR surveys of star forming regions (SFRs) in order to seek for very low-mass young stellar populations. First is a deep JHKs-bands (simultaneous) survey with the SIRIUS camera on the IRSF 1.4m or the UH 2.2m telescopes. Second is a very deep JHKs survey with the CISCO IR camera on the Subaru 8.2m telescope. Third is a high resolution companion search around nearby YSOs with the CIAO adaptive optics coronagraph IR camera on the Subaru. In this contribution, we describe our SIRIUS camera and present preliminary results of the ongoing surveys with this new instrument.

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