A Complete Study on Various Area Filling Strategies Used in Weld Deposition-Based Additive Manufacturing

2021 ◽  
pp. 279-296
Author(s):  
Kishore Kumar Panchagnula ◽  
Jayaprakash Sharma Panchagnula
Keyword(s):  
Additive Manufacturing ◽  
Complete Study ◽  
Area Filling

Optimal space filling for additive manufacturing

2016 ◽  
Vol 22 (4) ◽  
pp. 660-675 ◽  
Author(s):  
Sajan Kapil ◽  
Prathamesh Joshi ◽  
Hari Vithasth Yagani ◽  
Dhirendra Rana ◽  
Pravin Milind Kulkarni ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Layered Manufacturing ◽  
Closed Curve ◽  
Numerical Control ◽  
Surface Finishing ◽  
Content Type ◽  
Single Pass ◽  
Connected Area ◽  
Area Filling

Purpose In additive manufacturing (AM) process, the physical properties of the products made by fractal toolpaths are better as compared to those made by conventional toolpaths. Also, it is desirable to minimize the number of tool retractions. The purpose of this study is to describe three different methods to generate fractal-based computer numerical control (CNC) toolpath for area filling of a closed curve with minimum or zero tool retractions. Design/methodology/approach This work describes three different methods to generate fractal-based CNC toolpath for area filling of a closed curve with minimum or zero tool retractions. In the first method, a large fractal square is placed over the outer boundary and then rest of the unwanted curve is trimmed out. To reduce the number of retractions, ends of the trimmed toolpath are connected in such a way that overlapping within the existing toolpath is avoided. In the second method, the trimming of the fractal is similar to the first method but the ends of trimmed toolpath are connected such that the overlapping is found at the boundaries only. The toolpath in the third method is a combination of fractal and zigzag curves. This toolpath is capable of filling a given connected area in a single pass without any tool retraction and toolpath overlap within a tolerance value equal to stepover of the toolpath. Findings The generated toolpath has several applications in AM and constant Z-height surface finishing. Experiments have been performed to verify the toolpath by depositing material by hybrid layered manufacturing process. Research limitations/implications Third toolpath method is suitable for the hybrid layered manufacturing process only because the toolpath overlapping tolerance may not be enough for other AM processes. Originality/value Development of a CNC toolpath for AM specifically hybrid layered manufacturing which can completely fill any arbitrary connected area in single pass while maintaining a constant stepover.

The Social Origins and Provenance of the English Bishops during the Reign of Edward II

1959 ◽  
Vol 9 ◽  
pp. 51-79
Author(s):  
K. Edwards
Keyword(s):  
Middle Ages ◽  
Social Background ◽  
Early Career ◽  
The Political ◽  
Social Origins ◽  
Political Activities ◽  
Edward Ii ◽  
The Social ◽  
Complete Study ◽  
History Of

During the last twenty or twenty-five years medieval historians have been much interested in the composition of the English episcopate. A number of studies of it have been published on periods ranging from the eleventh to the fifteenth and early sixteenth centuries. A further paper might well seem superfluous. My reason for offering one is that most previous writers have concentrated on analysing the professional circles from which the bishops were drawn, and suggesting the influences which their early careers as royal clerks, university masters and students, secular or regular clergy, may have had on their later work as bishops. They have shown comparatively little interest in their social background and provenance, except for those bishops who belonged to magnate families. Some years ago, when working on the political activities of Edward II's bishops, it seemed to me that social origins, family connexions and provenance might in a number of cases have had at least as much influence on a bishop's attitude to politics as his early career. I there fore collected information about the origins and provenance of these bishops. I now think that a rather more careful and complete study of this subject might throw further light not only on the political history of the reign, but on other problems connected with the character and work of the English episcopate. There is a general impression that in England in the later middle ages the bishops' ties with their dioceses were becoming less close, and that they were normally spending less time in diocesan work than their predecessors in the thirteenth century.

Cluster analysis for large data sets: applications to individual aerosol particles from the mid-pacific

1992 ◽  
Vol 50 (2) ◽  
pp. 1488-1489
Author(s):  
Thomas W. Shattuck ◽  
James R. Anderson ◽  
Neil W. Tindale ◽  
Peter R. Buseck
Keyword(s):  
Cluster Analysis ◽  
Chemical Reactivity ◽  
Large Data ◽  
Large Data Sets ◽  
Particle Analysis ◽  
Data Sets ◽  
Halogen Chemistry ◽  
Complete Study ◽  
Components Analysis ◽  
Automated Scanning

Individual particle analysis involves the study of tens of thousands of particles using automated scanning electron microscopy and elemental analysis by energy-dispersive, x-ray emission spectroscopy (EDS). EDS produces large data sets that must be analyzed using multi-variate statistical techniques. A complete study uses cluster analysis, discriminant analysis, and factor or principal components analysis (PCA). The three techniques are used in the study of particles sampled during the FeLine cruise to the mid-Pacific ocean in the summer of 1990. The mid-Pacific aerosol provides information on long range particle transport, iron deposition, sea salt ageing, and halogen chemistry.Aerosol particle data sets suffer from a number of difficulties for pattern recognition using cluster analysis. There is a great disparity in the number of observations per cluster and the range of the variables in each cluster. The variables are not normally distributed, they are subject to considerable experimental error, and many values are zero, because of finite detection limits. Many of the clusters show considerable overlap, because of natural variability, agglomeration, and chemical reactivity.

Regeneration von Knochendefekten mit computergesteuerter Herstellung von Gerüstträgern

2013 ◽  
Vol 22 (03) ◽  
pp. 180-187 ◽  
Author(s):  
J. Henke ◽  
J. T. Schantz ◽  
D. W. Hutmacher
Keyword(s):  
Tissue Engineering ◽  
Additive Manufacturing ◽  
Custom Made

ZusammenfassungDie Behandlung ausgedehnter Knochen-defekte nach Traumata oder durch Tumoren stellt nach wie vor eine signifikante Heraus-forderung im klinischen Alltag dar. Aufgrund der bestehenden Limitationen aktueller Therapiestandards haben Knochen-Tissue-Engineering (TE)-Verfahren zunehmend an Bedeutung gewonnen. Die Entwicklung von Additive-Manufacturing (AM)-Verfahren hat dabei eine grundlegende Innovation ausgelöst: Durch AM lassen sich dreidimensionale Gerüstträger in einem computergestützten Schichtfür-Schicht-Verfahren aus digitalen 3D-Vorlagen erstellen. Wurden mittels AM zunächst nur Modelle zur haptischen Darstellung knöcherner Pathologika und zur Planung von Operationen hergestellt, so ist es mit der Entwicklung nun möglich, detaillierte Scaffoldstrukturen zur Tissue-Engineering-Anwendung im Knochen zu fabrizieren. Die umfassende Kontrolle der internen Scaffoldstruktur und der äußeren Scaffoldmaße erlaubt eine Custom-made-Anwendung mit auf den individuellen Knochendefekt und die entsprechenden (mechanischen etc.) Anforderungen abgestimmten Konstrukten. Ein zukünftiges Feld ist das automatisierte ultrastrukturelle Design von TE-Konstrukten aus Scaffold-Biomaterialien in Kombination mit lebenden Zellen und biologisch aktiven Wachstumsfaktoren zur Nachbildung natürlicher (knöcherner) Organstrukturen.

A novel predictive method for filler coflocculation with cellulose microfibrils

TAPPI Journal ◽  
2019 ◽  
Vol 18 (11) ◽  
pp. 653-664
Author(s):  
IGNACIO DE SAN PIO ◽  
KLAS G. JOHANSSON ◽  
PAUL KROCHAK
Keyword(s):  
Negative Impact ◽  
High Strength ◽  
Strength Properties ◽  
Cellulose Microfibrils ◽  
Paper Strength ◽  
Flow Loop ◽  
Cationic Starch ◽  
Reflectance Measurement ◽  
Drainage Rate ◽  
Complete Study

Different strategies aimed at reducing the negative impact of fillers on paper strength have been the objective of many studies during the past few decades. Some new strategies have even been patented or commercialized, yet a complete study on the behavior of the filler flocs and their effect on retention, drainage, and formation has not been found in literature. This type of research on fillers is often limited by difficulties in simulating high levels of shear at laboratory scale similar to those at mill scale. To address this challenge, a combination of techniques was used to compare preflocculation (i.e., filler is flocculated before addition to the pulp) with coflocculation strategies (i.e., filler is mixed with a binder and flocculated before addition to the pulp). The effect on filler and fiber flocs size was studied in a pilot flow loop using focal beam reflectance measurement (FBRM) and image analysis. Flocs obtained with cationic polyacrylamide (CPAM) and bentonite were shown to have similar shear resistance with both strategies, whereas cationic starch (CS) was clearly more advantageous when coflocculation strategy was used. The effect of flocculation strategy on drainage rate, STFI formation, ash retention, and standard strength properties was measured. Coflocculation of filler with CPAM plus bentonite or CS showed promising results and produced sheets with high strength but had a negative impact on wire dewatering, opening a door for further optimization.

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