scholarly journals Maximum Utilization in Operations Scheduling for Multiple Machines and Batches in Additive Manufacturing

2021 ◽  
pp. 1-14
Author(s):  
Salvador Castillo-Rivera
Keyword(s):  
Additive Manufacturing ◽  
Work Organization ◽  
Three Dimensional ◽  
Optimal Solutions ◽  
Planning And Control ◽  
Operations Scheduling ◽  
3D Printers ◽  
And Control ◽  
Operation Scheduling ◽  
Maximum Utilization

Scheduling and sequencing are forms of decision making that present a fundamental role in Additive Manufacturing (AM). This work studies the scheduling for a set of three-dimensional (3D) printers when the maximum utilization is used as an indicator. The aim is to establish a criterion that minimizes the use of available resources. A program has been done by using the software package Python and this has allowed studying the effect that the maximum utilization presents on operation scheduling. As evaluated a large number of pieces of various sizes, the analysis is found to be effective in yielding near-optimal solutions. The obtained outcomes have identified aspects of the production such as production planning and control as well as work organization.

Additive Manufacturing of Porous Ceramics with Foaming Agent

2021 ◽  
pp. 1-21
Author(s):  
Zipeng Guo ◽  
Lu An ◽  
Sushil Lakshmanan ◽  
Jason Armstrong ◽  
Shenqiang Ren ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Ambient Pressure ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Cost Effective ◽  
Tensile Tests ◽  
Porous Ceramics ◽  
Foaming Agent ◽  
Printing Quality ◽  
And Control

Abstract The macro-porous ceramics has promising durability and thermal insulation performance. As porous ceramics find more and more applications across many industries, a cost-effective and scalable additive manufacturing technique for fabricating macro-porous ceramics is highly desirable. Herein, we reported a facile additive manufacturing approach to fabricate porous ceramics and control the printed porosity. Several printable ceramic inks were prepared, the foaming agent was added to generate gaseous bubbles in the ink, followed by the direct ink writing and the ambient-pressure and room-temperature drying to create the three-dimensional geometries. A set of experimental studies were performed to optimize the printing quality. The results revealed the optimal process parameters for printing the foamed ceramic ink with a high spatial resolution and fine surface quality. Varying the concentration of the foaming agent enables the controllability of the structural porosity. The maximum porosity can reach 85%, with a crack-free internal porous structure. The tensile tests showed that the printed macro-porous ceramics possessed enhanced durability with the addition of fiber. With a high-fidelity 3D printing process and the precise controllability of the porosity, we showed that the printed samples exhibited a remarkably low thermal conductivity and durable mechanical strength.

Complex Unconstrained Three-Dimensional Hand Movement and Constant Equi-Affine Speed

2009 ◽  
Vol 101 (2) ◽  
pp. 1002-1015 ◽  
Author(s):  
Uri Maoz ◽  
Alain Berthoz ◽  
Tamar Flash
Keyword(s):  
Power Law ◽  
Hand Movement ◽  
Three Dimensional ◽  
Hand Movements ◽  
Human Hand ◽  
Local Geometry ◽  
Planning And Control ◽  
Human Movements ◽  
And Control ◽  
Geometry And Kinematics

One long-established simplifying principle behind the large repertoire and high versatility of human hand movements is the two-thirds power law—an empirical law stating a relationship between local geometry and kinematics of human hand trajectories during planar curved movements. It was further generalized not only to various types of human movements, but also to motion perception and prediction, although it was unsuccessful in explaining unconstrained three-dimensional (3D) movements. Recently, movement obeying the power law was proved to be equivalent to moving with constant planar equi-affine speed. Generalizing such motion to 3D space—i.e., to movement at constant spatial equi-affine speed—predicts the emergence of a new power law, whose utility for describing spatial scribbling movements we have previously demonstrated. In this empirical investigation of the new power law, subjects repetitively traced six different 3D geometrical shapes with their hand. We show that the 3D power law explains the data consistently better than both the two-thirds power law and an additional power law that was previously suggested for spatial hand movements. We also found small yet systematic modifications of the power-law's exponents across the various shapes, which further scrutiny suggested to be correlated with global geometric factors of the traced shape. Nevertheless, averaging over all subjects and shapes, the power-law exponents are generally in accordance with constant spatial equi-affine speed. Taken together, our findings provide evidence for the potential role of non-Euclidean geometry in motion planning and control. Moreover, these results seem to imply a relationship between geometry and kinematics that is more complex than the simple local one stipulated by the two-thirds power law and similar models.

scholarly journals Three-dimensional visualization of mission planning and control for the NPS autonomous underwater vehicle

1990 ◽  
Vol 15 (3) ◽  
pp. 217-221 ◽  
Author(s):  
M.J. Zyda ◽  
R.B. McGhee ◽  
S. Kwak ◽  
D.B. Nordman ◽  
R.C. Rogers ◽  
...  
Keyword(s):  
Autonomous Underwater Vehicle ◽  
Three Dimensional ◽  
Underwater Vehicle ◽  
Mission Planning ◽  
Planning And Control ◽  
And Control

Planning and control of three-dimensional multi-agent formations

2012 ◽  
Vol 30 (2) ◽  
pp. 265-284 ◽  
Author(s):  
G. Wen ◽  
Z. Peng ◽  
Y. Yu ◽  
A. Rahmani
Keyword(s):  
Three Dimensional ◽  
Planning And Control ◽  
Multi Agent ◽  
And Control

Singularity Loci of a Special Class of Spherical 3-DOF Parallel Mechanisms With Prismatic Actuators

2004 ◽  
Vol 126 (2) ◽  
pp. 319-326 ◽  
Author(s):  
Jing Wang ◽  
Cle´ment M. Gosselin
Keyword(s):  
Special Class ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Joint Space ◽  
Parallel Mechanisms ◽  
Singular Configurations ◽  
Planning And Control ◽  
Robot Trajectory ◽  
Special Cases ◽  
And Control

In this paper, the singularity loci of a special class of spherical 3-DOF parallel manipulators with prismatic actuators are studied. Concise analytical expressions describing the singularity loci are obtained in the joint and in the Cartesian spaces by using the expression of the determinant of the Jacobian matrix and the inverse kinematics of the manipulators. It is well known that there exist three different types of singularities for parallel manipulators, each having a different physical interpretation. In general, the singularity of type II is located inside the Cartesian workspace and leads to the instability of the end-effector. Therefore, it is important to be able to identify the configurations associated with this type of singularity and to find their locus in the space of all configurations. For the class of manipulators studied here, the six general cases and the five special cases of singularities are discussed. It is shown that the singularity loci in the Cartesian space (defined by the three Euler angles) are six independent planes. In the joint space (defined by the length of the three input links), the singularity loci are quadric surfaces, such as hyperboloid, sphere or a degenerated line or a degenerated circle. In addition, the three-dimensional graphical representations of the singular configurations in each of the general and special cases are illustrated. The description of the singular configurations provided here has great significance for robot trajectory planning and control.

PLANNING TO MEET THE GROWING DEMANDS ON NORTHLANDS WATER RESOURCES

1986 ◽  
pp. 33-42
Author(s):  
D.L. Roke
Keyword(s):  
Industrial Development ◽  
Water Resource Management ◽  
Limited Resources ◽  
Careful Planning ◽  
Management Planning ◽  
Planning And Control ◽  
Sources Of Pollution ◽  
And Control ◽  
Resource Management Planning ◽  
Pastoral Farming

The growth in horticultural and some industrial development in selected areas of Northland has led to a need for more specific and careful planning and control of limited resources in a number of major catchments. The potential irrigation demands for horhculture comprise over 60% of Northland's potential water requirements. By contrast, farm water supply needs are only 11% of these needs. Because of their importance to the Northland economy, and in the legislation these needs are given a high priority in water resource management planning. Land uses, including pastoral farming, require careful operation to reduce diffuse sources of pollution.

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