Disassembling a 3D mechanism for efficient packing

2018 ◽  
Vol 30 (2) ◽  
pp. e1861
Author(s):  
Mingyuan Li ◽  
Xiaoheng Jiang ◽  
Ningbo Gu ◽  
Weiwei Xu ◽  
Junxiao Xue ◽  
...  
Keyword(s):  
Efficient Packing

AN EFFICIENT APPROACH FOR THE THREE-DIMENSIONAL CONTAINER PACKING PROBLEM WITH PRACTICAL CONSTRAINTS

2004 ◽  
Vol 21 (03) ◽  
pp. 279-295 ◽  
Author(s):  
ZHIHONG JIN ◽  
KATSUHISA OHNO ◽  
JIALI DU
Keyword(s):  
Three Dimensional ◽  
Real Life ◽  
Packing Problem ◽  
Utilization Rate ◽  
Benchmark Problems ◽  
Rectangular Container ◽  
Efficient Packing ◽  
High Degree ◽  
Practical Constraints ◽  
Inherent Stability

This paper deals with the three-dimensional container packing problem (3DCPP), which is to pack a number of items orthogonally onto a rectangular container so that the utilization rate of the container space or the total value of loaded items is maximized. Besides the above objectives, some other practical constraints, such as loading stability, the rotation of items around the height axis, and the fixed loading (unloading) orders, must be considered for the real-life 3DCPP. In this paper, a sub-volume based simulated annealing meta-heuristic algorithm is proposed, which aims at generating flexible and efficient packing patterns and providing a high degree of inherent stability at the same time. Computational experiments on benchmark problems show its efficiency.

scholarly journals Ideal supplementary cementing material – Metakaolin: A review

2020 ◽  
Vol 11 (1) ◽  
pp. 58-65
Author(s):  
G. Lizia Thankam ◽  
Neelakantan Thurvas Renganathan
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Mineral Admixture ◽  
Homogeneous Material ◽  
Interfacial Zone ◽  
Supplementary Cementing Materials ◽  
Pozzolanic Material ◽  
Efficient Packing ◽  
Cementing Material ◽  
Zone Microstructure

AbstractThough being an ancient trend, usage of the homogeneous material cement in the construction industry is steadily getting eradicated with the springing up of supplementary cementing materials (SCM). Metakaolin is an imminent mineral admixture extracted from the mineral ore kaolinite, which enhances the interfacial zone by more efficient packing at the cement paste-aggregate particle interface, thus reducing the bleeding and producing a denser, more homogeneous transition zone microstructure. This paper depicts the various repercussions of the pozzolanic material metakaolin in the fresh and hardened properties of concrete when replaced with cement in finite amount. Also, it states the behavior of high-performance concrete and self-compacting concrete with metakaolin.

Synthesis and structural characteristics of lithocholate triads: steroid-type channels occupied by spacer fragments

2008 ◽  
Vol 64 (3) ◽  
pp. 383-392 ◽  
Author(s):  
Urszula Rychlewska ◽  
Beata Warżajtis ◽  
Roman Joachimiak ◽  
Zdzisław Paryzek
Keyword(s):  
Inclusion Complexes ◽  
Terephthalic Acid ◽  
Lithocholic Acid ◽  
Structural Characteristics ◽  
Guest Molecules ◽  
Face To Face ◽  
Bifunctional Molecules ◽  
Hydrogen Bond Interactions ◽  
Crystal Density ◽  
Efficient Packing

Reported in this paper are the syntheses and X-ray investigations of C 2 symmetrical molecular A—B—A triads consisting of two steroid units (lithocholic acid or its methyl ester) joined together by linkers derived from bifunctional molecules such as terephthalic acid or N,N′-dicarboxypiperazine. Unlike their monomeric analogues, some of these compounds form inclusion complexes. All steroidal triads form crystals that are highly pseudo-centrosymmetric, in which the constituting molecules are held together either exclusively by van der Waals forces or form lattice inclusion complexes, with guest molecules hydrogen bonded to the host. The presence of carboxyl groups promotes the inclusion of pyridine molecules and the formation of the well known carboxylic acid...pyridine hydrogen bonds. Combined with pairwise face-to-face π-stacking between pyridine rings, these hydrogen-bond interactions lead to the formation of extended supramolecular tapes, analogous to polymers. The co-crystals of pyridine and a lithocholic acid triad undergo a symmetry-lowering phase transition from a P1 cell with Z = 1 to a P1 cell with Z = 2. The two structures are virtually the same, the two independent molecules in the larger cell being related by pseudo-translation. Changes in the type of spacer between two methyl lithocholate units from planar aromatic (terephthalic acid) to highly puckered aliphatic six-membered ring (N,N′-dicarboxypiperazine) bring about inclusion properties and changes in side-chain conformation in a crystal. Although the efficient packing of these highly elongated molecules is hindered, as indicated by low values of crystal density, ranging from 1.16 to 1.19 g cm−3, several very short C...O and H...H contacts are present in the crystals.

The use of restraints in Rietveld refinement of molecular compounds; a case study using the crystal structure determination of tryptamine free base

2002 ◽  
Vol 58 (5) ◽  
pp. 835-840 ◽  
Author(s):  
Harriott Nowell ◽  
J. Paul Attfield ◽  
Jason C. Cole
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Free Base ◽  
Final Choice ◽  
X Ray ◽  
Global Weight ◽  
Efficient Packing ◽  
Molecular Compounds

The previously unknown crystal structure of the biogenic compound tryptamine, in the form of a free base (C10H12N2), has been solved from X-ray powder diffraction data using simulated annealing followed by restrained Rietveld refinement [space group P212121, a = 12.28593 (6), b = 8.53351 (4), c = 8.49385 (4) Å, Z = 4, final reduced-χ2 = 5.255]. A restrained Rietveld refinement was carried out in which the global weight factor, f, of the stereochemical restraints was gradually lowered. The effect of the relaxation of restraints on the crystal structure and on χ2 was studied and a criterion for the final choice of f is reported. The crystal structure reported here shows efficient packing involving weak intermolecular hydrogen bonding and a herringbone-type packing pattern.

scholarly journals Fundamental helical geometry consolidates the plant photosynthetic membrane

2019 ◽  
Vol 116 (44) ◽  
pp. 22366-22375 ◽  
Author(s):  
Yuval Bussi ◽  
Eyal Shimoni ◽  
Allon Weiner ◽  
Ruti Kapon ◽  
Dana Charuvi ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Photosynthetic Membrane ◽  
Lamellar System ◽  
Left Handed ◽  
Dense Nuclear Matter ◽  
Theoretical Predictions ◽  
Stroma Lamellae ◽  
Helical Geometry ◽  
The Right ◽  
Efficient Packing

Plant photosynthetic (thylakoid) membranes are organized into complex networks that are differentiated into 2 distinct morphological and functional domains called grana and stroma lamellae. How the 2 domains join to form a continuous lamellar system has been the subject of numerous studies since the mid-1950s. Using different electron tomography techniques, we found that the grana and stroma lamellae are connected by an array of pitch-balanced right- and left-handed helical membrane surfaces of different radii and pitch. Consistent with theoretical predictions, this arrangement is shown to minimize the surface and bending energies of the membranes. Related configurations were proposed to be present in the rough endoplasmic reticulum and in dense nuclear matter phases theorized to exist in neutron star crusts, where the right- and left-handed helical elements differ only in their handedness. Pitch-balanced helical elements of alternating handedness may thus constitute a fundamental geometry for the efficient packing of connected layers or sheets.

Synthesis, crystallization, X-ray structural characterization and solid-state assembly of a cyclic hexapeptoid with propargyl and methoxyethyl side chains

2017 ◽  
Vol 73 (3) ◽  
pp. 399-412 ◽  
Author(s):  
Consiglia Tedesco ◽  
Eleonora Macedi ◽  
Alessandra Meli ◽  
Giovanni Pierri ◽  
Giorgio Della Sala ◽  
...  
Keyword(s):  
Solid State ◽  
Hydrogen Bonds ◽  
Structural Characterization ◽  
Crystal Form ◽  
Side Chains ◽  
Crystal Forms ◽  
Hydrate Crystal ◽  
The Stability ◽  
Efficient Packing

The synthesis and the structural characterization of a cyclic hexapeptoid with four methoxyethyl and two propargyl side chains have disclosed the presence of a hydrate crystal form [form (I)] and an anhydrous crystal form [form (II)]. The relative amounts of form (I) and form (II) in the as-purified product were determined by Rietveld refinement and depend on the purification procedures. In crystal form (I), peptoid molecules assemble in a columnar arrangement by means of side-chain-to-backbone C=CH...OC hydrogen bonds. In the anhydrous crystal form (II), cyclopeptoid molecules form ribbons by means of backbone-to-backbone CH2...OC hydrogen bonds, thus mimicking β-sheet secondary structures in proteins. In both crystal forms side chains act as joints among the columns or the ribbons and contribute to the stability of the whole solid-state assembly. Water molecules in the hydrate crystal form (I) bridge columns of cyclic peptoid molecules, providing a more efficient packing.

New 3D geometrical deposition methods for efficient packing of spheres based on tangency

2015 ◽  
Vol 104 (12) ◽  
pp. 1085-1114 ◽  
Author(s):  
F. De Cola ◽  
S. Falco ◽  
E. Barbieri ◽  
N. Petrinic
Keyword(s):  
Efficient Packing

scholarly journals Texture and Microstructure Development in Al2O3-Platelet Reinforced Ce-ZrO2/Al2O3 Laminates Produced by Centrifugal Consolidation

1995 ◽  
Vol 24 (1-3) ◽  
pp. 43-52 ◽  
Author(s):  
Ryan K. Roeder ◽  
Keith J. Bowman ◽  
Kevin P. Trumble
Keyword(s):  
Microstructural Evolution ◽  
Volume Fraction ◽  
Phase Segregation ◽  
Functionally Gradient ◽  
Property Evaluation ◽  
Quantitative Image ◽  
Microstructural Design ◽  
Efficient Packing ◽  
And Control ◽  
Platelet Content

A dispersed, low-solids-fraction suspension containing Ce-ZrO2, fine Al2O3 and 5 vol% Al2O3-platelets was segregated using centrifugal consolidation to produce functionally gradient laminates (FGLs). Platelet alignment facilitated efficient packing of highly anisometric platelets to high densities. The complexity and anisotropy of the microstructure warrants a quantitative analysis of the microstructural evolution prior to any property evaluation. Quantitative image analysis was used to examine changes in the volume fraction, dimensional anisotropy, and gradient of pores and platelets with sintering time. In all cases, special attention was given to the effects of texture during microstructural evolution. Platelet alignment enhanced densification via anisotropic shrinkage, overcoming constraint that otherwise inhibits densification in platelet-containing materials. Also, platelet alignment and microstructural design were used to initiate and control anisotropic grain growth. Platelet growth (at the expense of smaller particles of the same phase) during annealing promoted further phase segregation and produced higher platelet content composites consisting of larger platelets, without having to consolidate high contents of large platelets.

Efficient Packing of Arbitrary Shaped Charts for Automatic Texture Atlas Generation

2011 ◽  
Vol 30 (4) ◽  
pp. 1309-1317 ◽  
Author(s):  
T. Nöll ◽  
D. Strieker
Keyword(s):  
Efficient Packing

A three-dimensional algorithm using two-dimensional slice data for building multiple parts in layered manufacturing

2000 ◽  
Vol 214 (5) ◽  
pp. 365-378 ◽  
Author(s):  
J Hur ◽  
K Lee ◽  
J Ahn ◽  
H C Lee
Keyword(s):  
Rapid Prototyping ◽  
Three Dimensional ◽  
Packing Problem ◽  
Optimal Placement ◽  
Normal Vector ◽  
Two Dimensional ◽  
Stl File ◽  
Work Volume ◽  
Time Required ◽  
Efficient Packing

In a rapid prototyping process, the time required to build multiple prototype parts can be reduced by building several parts simultaneously in a work volume. Interactive arrangement of the multiple parts, called three-dimensional nesting, is a tedious process and does not guarantee the optimal placement of all the parts. The three-dimensional nesting is well known as a problem requiring intense computation. Thus, an efficient algorithm to solve this problem is still under investigation. This paper presumes that the three-dimensional packing problem can be simplified into a set of two-dimensional irregular polygon nesting problems for each layer to take advantage of the characteristic of a rapid prototyping process, i. e. the process eventually uses two-dimensional slicing data of the STL file. The proposed algorithm uses a no-fit polygon (NFP) to calculate the allowable locations of each slice of a part such that it does not overlap other existing slices in the same z level. Then the allowable position of the part with respect to other parts already located in a work volume can be determined by obtaining the union of all NFPs that are obtained from each slice of the part. Additionally, a genetic algorithm is used to try and determine the various orders of the placement of the part and the various orientations of each part for efficient packing. Various orientations of a part are examined by rotating it about the normal vector of the slice in finite angles and by inversion. The proposed algorithm can be applied to a rapid prototyping process that does not use support structures.

Sign in / Sign up

Export Citation Format

Share Document