scholarly journals Computation of Compact Distributions of Discrete Elements

Algorithms ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 41
Author(s):  
Jie Chen ◽  
Gang Yang ◽  
Meng Yang

In our daily lives, many plane patterns can actually be regarded as a compact distribution of a number of elements with certain shapes, like the classic pattern mosaic. In order to synthesize this kind of pattern, the basic problem is, with given graphics elements with certain shapes, to distribute a large number of these elements within a plane region in a possibly random and compact way. It is not easy to achieve this because it not only involves complicated adjacency calculations, but also is closely related to the shape of the elements. This paper attempts to propose an approach that can effectively and quickly synthesize compact distributions of elements of a variety of shapes. The primary idea is that with the seed points and distribution region given as premise, the generation of the Centroidal Voronoi Tesselation (CVT) of this region by iterative relaxation and the CVT will partition the distribution area into small regions of Voronoi, with each region representing the space of an element, to achieve a compact distribution of all the elements. In the generation process of Voronoi diagram, we adopt various distance metrics to control the shape of the generated Voronoi regions, and finally achieve the compact element distributions of different shapes. Additionally, approaches are introduced to control the sizes and directions of the Voronoi regions to generate element distributions with size and direction variations during the Voronoi diagram generation process to enrich the effect of compact element distributions. Moreover, to increase the synthesis efficiency, the time-consuming Voronoi diagram generation process was converted into a graphical rendering process, thus increasing the speed of the synthesis process. This paper is an exploration of elements compact distribution and also carries application value in the fields like mosaic pattern synthesis.

2012 ◽  
Vol 588-589 ◽  
pp. 802-805
Author(s):  
Ban Teng Liu ◽  
Xi Lin Hu ◽  
Zheng Yu Xu ◽  
Yao Lin Liu ◽  
You Rong Chen

This paper propose a two-tiered network in which lower-power users communicate with one another through repeaters, which amplify signals and retransmit them, have limited capacity, and may interfere with one another if their transmitter frequencies are close and they share the same private-line tone. Motivated by cellular networks, this paper gives a naive solution where the number of repeaters and their positions can be obtained analytically. In a circular area with radius 40 miles, 12 repeaters can accommodate 1,000 simultaneous users. This paper further propose an iterative refinement algorithm consisting of three fundamental modules that draw the Voronoi diagram, determine the centers of the circumscribed circles of the Voronoi regions, and escape the local optimum by using external optimization. The algorithm obtains a solution with 11 repeaters, which we prove to be the absolute minimum. For 10,000 users, it uses 104 repeaters, better than the naive solution's 108.


2008 ◽  
Vol 18 (04) ◽  
pp. 275-294 ◽  
Author(s):  
ROBERT GÖRKE ◽  
CHAN-SU SHIN ◽  
ALEXANDER WOLFF

Given a set P of n point sites in the plane, the city Voronoi diagram subdivides the plane into the Voronoi regions of the sites, with respect to the city metric. This metric is induced by quickest paths according to the Manhattan metric and an accelerating transportation network that consists of c non-intersecting axis-parallel line segments. We describe an algorithm that constructs the city Voronoi diagram (including quickest path information) using O((c+n) polylog (c+n)) time and storage by means of a wavefront expansion. For [Formula: see text] our algorithm is faster than an algorithm by Aichholzer et al., which takes O(n log n + c2 log c) time.


2013 ◽  
Vol 318 ◽  
pp. 395-398 ◽  
Author(s):  
Sha Sha Gao ◽  
Hong Jie Wang ◽  
Xiang Hao Wang ◽  
Jing Jing Fan ◽  
Xin Zhang

Yanji Depression was formed on the base of Upper Paleozoic strata. Distribution area of Carboniferous-Permian strata is about 1550km 2 , and the strata are preserved intact. By researching on the thermal evolution analysis of hydrocarbon source rock and the source-reservoir-cap combination, the hydrocarbon generation and exploration prospect was studied. The results show that the thickness and the depth of Carboniferous-Permian strata are great, and organic matter maturity is on the stage of high mature-past mature, and it has two stages of hydrocarbon generation process, and the residual hydrocarbon generation potential is low. Upper Paleozoic, Mesozoic and Cenozoic have extensive sandstone reservoir, and have favorable territorial cap rock. It forms two types of source- reservoir- cap assemblage, and has great Hydrocarbon Resource Potential. After analysis the unconventional oil and gas, it shows that Yanji depression has the formation condition of tight sandstone gas and shale gas.


2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Wentao Li ◽  
Yongqiang Hei ◽  
Jing Yang ◽  
Xiaowei Shi

This paper addresses the synthesis of the three-dimensional (3D) radiation patterns of the time-modulated conformal arrays. Due to the nature of periodic time modulation, harmonic radiation patterns are generated at the multiples of the modulation frequency in time-modulated arrays. Thus, the optimization goal of the time-modulated conformal array includes the optimization of the sidelobe level at the operating frequency and the sideband levels (SBLs) at the harmonic frequency, and the design can be regarded as a multiobjective problem. The multiobjective particle swarm optimization (MOPSO) is applied to optimize the switch-on instants and pulse durations of the time-modulated conformal array. To significantly reduce the optimization variables, the modified Bernstein polynomial is employed in the synthesis process. Furthermore, dual polarized patch antenna is designed as radiator to achieve low cross-polarization level during the beam scanning. A 12 × 13 (156)-element conical conformal microstrip array is simulated to demonstrate the proposed synthesis mechanism, and good results reveal the promising ability of the proposed algorithm in solving the synthesis of the time-modulated conformal arrays problem.


2020 ◽  
Vol 1 (2) ◽  
pp. 159-175
Author(s):  
Yuuhi Okahana ◽  
Yusuke Gotoh

Due to the recent popularization of the Geographic Information System (GIS), spatial network environments that can display the changes of spatial axes on mobile devices are receiving great attention. In spatial network environments, since a query object that seeks location information selects several candidate target objects based on the search conditions, we often use a k-nearest neighbor (kNN) search, which seeks several target objects near the query object. However, since a kNN search needs to find the kNN by calculating the distance from the query to all the objects, the computational complexity might become too large based on the number of objects. To reduce this computation time in a kNN search, many researchers have proposed a search method that divides regions using a Voronoi diagram. However, since conventional methods generate Voronoi diagrams for objects in order, the processing time for generating Voronoi diagrams might become too large when the number of objects is increased. In this paper, we propose a generation method of the Voronoi diagram by parallelizing the generation of Voronoi regions using a contact zone. Our proposed method can reduce the processing time of generating the Voronoi diagram by generating Voronoi regions in parallel based on the number of targets. Our evaluation confirmed that the processing time under the proposed method was reduced about 15.9\% more than conventional methods that are not parallelized.


Author(s):  
Keikichi Hirose

After starting as an effort to mimic the human process of speech sound generation, the quality of synthetic speech has reached a level that makes it difficult to notice that it is synthetic. This owes to the development of waveform concatenation methods which select the most appropriate speech segments from a huge speech corpus. Although the lack of flexibility in producing various speech qualities/styles has been pointed out, this problem is about to be solved by introducing statistical frameworks into parametric speech synthesis. Now, a speaker can even speak a foreign language in his/her voice using advanced voice-conversion techniques. However, if we consider prosodic features of speech, current technologies are not appropriate to handle their hierarchical structure over a long time span. Introduction of prosody modelling into the speech-synthesis process is necessary. In this chapter, after viewing the history of voice/speech synthesis, technologies are explained, starting from text-to-speech and concept-to-speech conversion. Then, methods of sound generation are introduced. Statistical parametric speech synthesis, especially HMM-based speech synthesis, is introduced as a technology that enables flexible speech synthesis—that is, synthetic speech with various qualities/styles requiring a smaller amount of speech corpus. After that, the problem of frame-by-frame processing for prosodic features is addressed and the importance of prosody modelling is pointed out. Prosodic (fundamental frequency) modelling is surveyed and, finally, the generation process model is introduced with some experimental results when applied to HMM-based speech synthesis.


Author(s):  
Merel van Diepen ◽  
Kristina Shea

Soft robots are intrinsically compliant, which makes them suitable for interaction with delicate objects and living beings. The vast design space and the complex dynamic behavior of the elastic body of the robots make designing them by hand challenging, often requiring a large number of iterations. It is thus advantageous to design soft robots using a computational design approach that integrates simulation feedback. Since locomotion is an essential component in many robotic tasks, this paper presents the computational design synthesis of soft, virtual, locomotion robots. Methods used in previous work give little insight into and control over the computational design synthesis process. The generated solutions are also highly irregular and very different to hand-designed solutions. Also, the problem requirements are solely modeled in the objective function. Here, designs are generated using a spatial grammar with a rule set that is deduced from known locomotion principles. Spatial grammars make it possible to define the type of morphologies that are generated. The aim is to generate gaits based on different locomotion principles, e.g. walking, hopping and crawling. By combining a spatial grammar with simulated annealing, the solution space is searched for locomotive designs. The designs are simulated using a mass-spring model with stable self-collision so that all generated designs can be evaluated. The resulting virtual designs exhibit a large variety of expected and unexpected gaits. The grammar is analyzed to understand the generation process and assess the performance. The main contribution of this research is modeling of some of the results in the spatial grammar rather than the objective function. Thus, the process is guided towards a class of designs with extremities for locomotion, without having to define the class explicitly. Further, the simulation approach is new and results in a stable method that accounts for self-collision.


2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Ahmet Emre Taser ◽  
Kerim Guney ◽  
Erhan Kurt

Antenna array synthesis is one of the most popular topics in the electromagnetic field. Since achieving a desired antenna radiation pattern is a mathematical problem, in the literature, there are various optimization algorithms applied to the synthesis process of different kinds of antenna arrays. In this study, Multiverse Optimizer (MVO) and modified MVO (MMVO) are used to perform circular antenna array (CAA) synthesis. During the exploration, exploitation, and local search phases of calculation, MVO uses three concepts in cosmology; white hole, black hole, and wormhole. Convergence capability of this nature-inspired algorithm is employed for finding optimum amplitude and position values of CAA elements in order to achieve an array pattern with low maximum sidelobe level (MSL) and minimum circumference. The performance of MVO and MMVO was tested on five design examples of pattern synthesis, and the obtained results were compared with ten different algorithms. The simulation results show that MVO and MMVO provide low MSLs with small circumferences.


2021 ◽  
Vol 1192 (1) ◽  
pp. 012015
Author(s):  
N I M Razali ◽  
F Ali ◽  
A S Azmi ◽  
T N M T Ismail ◽  
M E S Mirghani ◽  
...  

Abstract Since its discovery, plastic has been a part of human life and is widely employed in our daily lives. Excessive use of plastic has raised pollution rates around the world, with plastic ending up in landfills or the sea, posing a threat to both terrestrial and aquatic life. Considering this problem, the widespread use of polyurethanes (PUs) in many industries has resulted in unavoidable PUs pollution in everyday life. A reaction involving prepolymer, isocyanate, and polyol can be used to make PUs. Petroleum-based polyol and vegetable oil-based polyol are the two types of polyols available. Isocyanate will become the hard domain of the polymer in the PUs polymer chain, while polyol will become the soft domain. Polylactic acid-diol is the prepolymer used to make PU (PLA-diol). PLA-diol was previously made using a traditional heating approach, which takes a long time. To overcome this traditional method, microwave-assisted synthesis is proposed to synthesize the PLA-diol. The synthesis process involved synthesizing PLA-diol at different microwave power (450W – 900W) and at different reaction time (1 hour – 2 hours). The peak of hydroxyl group in synthesized PLA-diol was characterized via the Fourier Transform Infrared Spectroscopy (FTIR) characterization to determine the functional groups of PLA-diol and gel permeation chromatography (GPC) characterization was done to determine the molecular weight of PLA-diol. The resulting PLA-diol will then be used to synthesis biodegradable PUs in the subsequence study.


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