Review: Dimensional Accuracy in Additive Manufacturing Processes

2014 ◽  
Author(s):  
Pil-Ho Lee ◽  
Haseung Chung ◽  
Sang Won Lee ◽  
Jeongkon Yoo ◽  
Jeonghan Ko
Keyword(s):  
Additive Manufacturing ◽  
State Of The Art ◽  
Dimensional Accuracy ◽  
The State ◽  
Manufacturing Processes ◽  
Accuracy Improvement ◽  
Process Characteristics ◽  
Art Research ◽  
Am Processes

This paper reviews the state-of-the-art research related to the dimensional accuracy in additive manufacturing (AM) processes. It is considered that the improvement of dimensional accuracy is one of the major scientific challenges to enhance the qualities of the products by AM. This paper analyzed the studies for commonly used AM techniques with respect to dimensional accuracy. These studies are classified by process characteristics, and relevant accuracy issues are examined. The accuracies of commercial AM machines are also listed. This paper also discusses suggestions for accuracy improvement. With the increase of the dimensional accuracy, not only the application of AM processes will diversify but also their value will increase.

Towards Update-Efficient and Parallel-Friendly Content-Based Indexing Scheme in Cloud Computing

2018 ◽  
Vol 12 (02) ◽  
pp. 191-213
Author(s):  
Nan Zhu ◽  
Yangdi Lu ◽  
Wenbo He ◽  
Hua Yu ◽  
Jike Ge
Keyword(s):  
Cloud Computing ◽  
State Of The Art ◽  
High Volume ◽  
Data Partitioning ◽  
The State ◽  
Computing Systems ◽  
Indexing System ◽  
Indexing Method ◽  
Concurrent User ◽  
Art Research

The sheer volume of contents generated by today’s Internet services is stored in the cloud. The effective indexing method is important to provide the content to users on demand. The indexing method associating the user-generated metadata with the content is vulnerable to the inaccuracy caused by the low quality of the metadata. While the content-based indexing does not depend on the error-prone metadata, the state-of-the-art research focuses on developing descriptive features and misses the system-oriented considerations when incorporating these features into the practical cloud computing systems. We propose an Update-Efficient and Parallel-Friendly content-based indexing system, called Partitioned Hash Forest (PHF). The PHF system incorporates the state-of-the-art content-based indexing models and multiple system-oriented optimizations. PHF contains an approximate content-based index and leverages the hierarchical memory system to support the high volume of updates. Additionally, the content-aware data partitioning and lock-free concurrency management module enable the parallel processing of the concurrent user requests. We evaluate PHF in terms of indexing accuracy and system efficiency by comparing it with the state-of-the-art content-based indexing algorithm and its variances. We achieve the significantly better accuracy with less resource consumption, around 37% faster in update processing and up to 2.5[Formula: see text] throughput speedup in a multi-core platform comparing to other parallel-friendly designs.

State-of-the-Art in Micro- and Meso-Scale Heat Exchangers

1999 ◽  
Author(s):  
Reza Shekarriz ◽  
Charles J. Call
Keyword(s):  
Heat Exchanger ◽  
Research And Development ◽  
Heat Exchangers ◽  
State Of The Art ◽  
The State ◽  
Manufacturing Processes ◽  
Review Of The Literature ◽  
Design Constraints ◽  
Recent Advances ◽  
Meso Scale

Abstract A review of the literature and the state-of-the-art in research and development of miniature heat exchangers is presented in this paper. The authors provide a discussion of what makes the micro- and meso-scales important, highlight the design constraints and challenges that surface when miniaturizing a heat exchanger, and outline and discuss the outstanding practical and scientific issues in this area. Finally, the most recent advances in manufacturing processes and application of these miniature heat exchangers are covered in this article.

Host–Based Intrusion Detection Systems

2014 ◽  
pp. 184-213
Author(s):  
Vít Bukač ◽  
Vashek Matyáš
Keyword(s):  
Intrusion Detection ◽  
Detection Method ◽  
State Of The Art ◽  
Research Trends ◽  
The State ◽  
Intrusion Detection Systems ◽  
Future Directions ◽  
Detection Systems ◽  
Research Findings ◽  
Art Research

In this chapter, the reader explores both the founding ideas and the state-of-the-art research on host-based intrusion detection systems. HIDSs are categorized by their intrusion detection method. Each category is thoroughly investigated, and its limitations and benefits are discussed. Seminal research findings and ideas are presented and supplied with comments. Separate sections are devoted to the protection against tampering and to the HIDS evasion techniques that are employed by attackers. Existing research trends are highlighted, and possible future directions are suggested.

Privacy and Trust Management Schemes of Wireless Sensor Networks

2010 ◽  
pp. 290-309 ◽  
Author(s):  
Riaz Ahmed Shaikh ◽  
Brian J. dAuriol ◽  
Heejo Lee ◽  
Sungyoung Lee
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Trust Management ◽  
State Of The Art ◽  
The State ◽  
Wireless Sensor ◽  
Security Issues ◽  
Management Schemes ◽  
Art Research

Until recently, researchers have focused on the cryptographic-based security issues more intensively than the privacy and trust issues. However, without the incorporation of trust and privacy features, cryptographic-based security mechanisms are not capable of singlehandedly providing robustness, reliability and completeness in a security solution. In this chapter, we present generic and flexible taxonomies of privacy and trust. We also give detailed critical analyses of the state-of-the-art research, in the field of privacy and trust that is currently not available in the literature. This chapter also highlights the challenging issues and problems.

scholarly journals 3D Printing in Heterogeneous Catalysis—The State of the Art

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4534 ◽  
Author(s):  
Elżbieta Bogdan ◽  
Piotr Michorczyk
Keyword(s):  
Additive Manufacturing ◽  
Heterogeneous Catalysis ◽  
3D Printing ◽  
Chemical Synthesis ◽  
State Of The Art ◽  
Three Dimensional ◽  
Production Method ◽  
The State ◽  
Monolithic Catalysts ◽  
Selection Of

This paper describes the process of additive manufacturing and a selection of three-dimensional (3D) printing methods which have applications in chemical synthesis, specifically for the production of monolithic catalysts. A review was conducted on reference literature for 3D printing applications in the field of catalysis. It was proven that 3D printing is a promising production method for catalysts.

But Will it Print?: Assessing Student Use of Design for Additive Manufacturing and Exploring its Effect on Design Performance and Manufacturability

2019 ◽  
Author(s):  
Rohan Prabhu ◽  
Scarlett R. Miller ◽  
Timothy W. Simpson ◽  
Nicholas A. Meisel
Keyword(s):  
Additive Manufacturing ◽  
Undergraduate Students ◽  
Educational Interventions ◽  
Support Material ◽  
Design Performance ◽  
Process Characteristics ◽  
Build Time ◽  
And Performance ◽  
Am Processes ◽  
Design For Am

Abstract Additive manufacturing (AM) enables engineers to improve the functionality and performance of their designs by adding complexity at little to no additional cost. However, AM processes also exhibit certain unique limitations, such as the presence of support material, which must be accounted for to ensure that designs can be manufactured feasibly and cost-effectively. Given these unique process characteristics, it is important for an AM-trained workforce to be able to incorporate both opportunistic and restrictive design for AM (DfAM) considerations into the design process. While AM/DfAM educational interventions have been discussed in the literature, limited research has investigated the effect of these interventions on students’ use of DfAM. Furthermore, limited research has explored how DfAM use affects the performance of students’ AM designs. This research explores this gap through an experimental study with 123 undergraduate students. Specifically, participants were exposed to either restrictive DfAM or dual DfAM (both opportunistic and restrictive) and then asked to participate in an AM design challenge. The students’ final designs were evaluated for (1) performance with respect the design objectives and constraints, and (2) the use of the various aspects of DfAM. The results showed that the use of certain DfAM considerations, such as minimum feature size and support material mass, successfully predicted the performance of the AM designs. Further, while the variations in DfAM education did not influence the performance of the AM designs, it did have an effect on the students’ use of certain DfAM concepts in their final designs. These results highlight the influence of DfAM education in bringing about an increase in students’ use of DfAM. Moreover, the results demonstrate the potential influence of DfAM in reducing build time and build material of the students’ AM designs, thus improving design performance and manufacturability.

scholarly journals Event Time Extraction with a Decision Tree of Neural Classifiers

2018 ◽  
Vol 6 ◽  
pp. 77-89 ◽  
Author(s):  
Nils Reimers ◽  
Nazanin Dehghani ◽  
Iryna Gurevych
Keyword(s):  
Decision Tree ◽  
State Of The Art ◽  
Time Frame ◽  
The State ◽  
Accuracy Improvement ◽  
Event Time ◽  
Current Events ◽  
Future Events ◽  
Novel Method ◽  
Time Information

Extracting the information from text when an event happened is challenging. Documents do not only report on current events, but also on past events as well as on future events. Often, the relevant time information for an event is scattered across the document. In this paper we present a novel method to automatically anchor events in time. To our knowledge it is the first approach that takes temporal information from the complete document into account. We created a decision tree that applies neural network based classifiers at its nodes. We use this tree to incrementally infer, in a stepwise manner, at which time frame an event happened. We evaluate the approach on the TimeBank-EventTime Corpus (Reimers et al., 2016) achieving an accuracy of 42.0% compared to an inter-annotator agreement (IAA) of 56.7%. For events that span over a single day we observe an accuracy improvement of 33.1 points compared to the state-of-the-art CAEVO system (Chambers et al., 2014). Without retraining, we apply this model to the SemEval-2015 Task 4 on automatic timeline generation and achieve an improvement of 4.01 points F1-score compared to the state-of-the-art. Our code is publically available.

scholarly journals Study of the Environmental Implications of Using Metal Powder in Additive Manufacturing and Its Handling

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 261 ◽  
Author(s):  
Jon Iñaki Arrizubieta ◽  
Olatz Ukar ◽  
Marta Ostolaza ◽  
Arantza Mugica
Keyword(s):  
Additive Manufacturing ◽  
Environmental Impact ◽  
Resource Use ◽  
Life Cycle Analysis ◽  
Chemical Compounds ◽  
Manufacturing Processes ◽  
Environmental Implications ◽  
Work Related ◽  
High Concentrations ◽  
Am Processes

Additive Manufacturing, AM, is considered to be environmentally friendly when compared to conventional manufacturing processes. Most researchers focus on resource consumption when performing the corresponding Life Cycle Analysis, LCA, of AM. To that end, the sustainability of AM is compared to processes like milling. Nevertheless, factors such as resource use, pollution, and the effects of AM on human health and society should be also taken into account before determining its environmental impact. In addition, in powder-based AM, handling the powder becomes an issue to be addressed, considering both the operator´s health and the subsequent management of the powder used. In view of these requirements, the fundamentals of the different powder-based AM processes were studied and special attention paid to the health risks derived from the high concentrations of certain chemical compounds existing in the typically employed materials. A review of previous work related to the environmental impact of AM is presented, highlighting the gaps found and the areas where deeper research is required. Finally, the implications of the reuse of metallic powder and the procedures to be followed for the disposal of waste are studied.

Additive Manufacturing Processes for Infrastructure Construction: A Review

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Abhinav Bhardwaj ◽  
Scott Z. Jones ◽  
Negar Kalantar ◽  
Zhijian Pei ◽  
John Vickers ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Construction Industry ◽  
Manufacturing Sector ◽  
Manufacturing Processes ◽  
Current State ◽  
Industry Applications ◽  
Am Processes

Additive manufacturing (AM) has had an enormous impact on the manufacturing sector. Its role has evolved from printing prototypes to manufacturing functional parts for a variety of applications in the automotive, aerospace, and medical industries. Recently, AM processes have also been applied in the infrastructure construction industry. Applications of AM processes could bring in significant improvements in infrastructure construction, specifically in the areas of productivity and safety. It is desirable to have a review on the current state of emerging AM processes for infrastructure construction and existing gaps in this field. This paper reviews the AM processes in infrastructure construction. It discusses the process principle, application examples, and gaps for each of the AM processes.

Sign in / Sign up

Export Citation Format

Share Document