scholarly journals Existence and Hardness of Conveyor Belts

10.37236/9782 ◽  
2020 ◽  
Vol 27 (4) ◽  
Author(s):  
Molly Baird ◽  
Sara Billey ◽  
Erik Demaine ◽  
Martin Demaine ◽  
David Eppstein ◽  
...  

An open problem of Manuel Abellanas asks whether every set of disjoint closed unit disks in the plane can be connected by a conveyor belt, which means a tight simple closed curve that touches the boundary of each disk, possibly multiple times. We prove three main results: For unit disks whose centers are both $x$-monotone and $y$-monotone, or whose centers have $x$-coordinates that differ by at least two units, a conveyor belt always exists and can be found efficiently. It is NP-complete to determine whether disks of arbitrary radii have a conveyor belt, and it remains NP-complete when we constrain the belt to touch disks exactly once. Any disjoint set of $n$ disks of arbitrary radii can be augmented by $O(n)$ "guide" disks so that the augmented system has a conveyor belt touching each disk exactly once, answering a conjecture of Demaine, Demaine, and Palop.


2016 ◽  
Author(s):  
Hanna Joos ◽  
Erica Madonna ◽  
Kasja Witlox ◽  
Sylvaine Ferrachat ◽  
Heini Wernli ◽  
...  

Abstract. While there is a clear impact of aerosol particles on the radiation balance, whether and how aerosol particles influence precipitation is controversial. Here we use the ECHAM6-HAM global cli- mate model coupled to an aerosol module to analyse whether an impact of anthropogenic aerosol particles on the timing and the amount of precipitation from warm conveyor belts in low pressure systems in the winter time North Pacific can be detected. We conclude that while polluted warm con- veyor belt trajectories start with 5–10 times higher black carbon concentrations, the overall amount of precipitation is comparable in pre-industrial and present-day conditions. Precipitation formation is however supressed in the most polluted warm conveyor belt trajectories.



2020 ◽  
Vol 5 (4) ◽  
pp. 111
Author(s):  
Yulia Resti ◽  
Firmansyah Burlian ◽  
Irsyadi Yani

The classification system in the sorting process in the can recycling industry can be made based on digital images by exploring the basic color pixel values ​​of images such as R, G, and B as variable inputs. In real time, the classification of cans in the sorting process occurs when cans placed on a conveyor belt move at a certain speed. This paper discusses the performance of can classification systems using the Naïve Bayes method. This method can handle all types of variables, including when all variables are continuous. Two types of conveyor belts are designed to get different speeds, and all images of the cans are captured on both conveyor belts. Two models of Bayes naive are built on the basis of the different distribution assumptions; the original model (all Gaussian distributed) and the model based on the best distribution. Performance of the classification system is built by dividing data into the learning data and the testing data with a composition of 50:50 in which each data is designed into 50 groups with different percentages on each type of cans using sampling technique without replacement. The results obtained are, first, the speed of the conveyor belt when capturing an image affects the pixel values of red, green, and blue and ultimately affects the results of the classification of cans. Second, not all input variables are Gaussian distributed. The classification system was built using assumption the best distribution model for each input variable has the better average accuracy level than the model that assumes all input variables are Gaussian distributed, and the accuracy level of classification on the first speeds of conveyor belt with a gear ratio of 12:30 and a diameter of 35 mm has an accuracy that is better than the other speed, both on the original model and the model based on the best distribution. However, it is necessary to test more statistical distribution models to obtain significant results.



2019 ◽  
Vol 18 (3) ◽  
pp. 223-232
Author(s):  
A. V. Glebov ◽  
G. D. Karmaev

Results of the analysis of scientific, technical and patent literature show that while having a great variety of constructive implementation of the proposed catchers there are no efficient and sufficiently reliable devices for catching conveyor belts at its reverse motion which are relatively simple in design. This is proved by practical activity of enterprises involved in extraction and processing of commercial minerals and other industries. A new design of a conveyor belt catcher that meets most requirements for the given equipment has been developed at the Institute of Mining, Ural of Branch of the Russian Academy of Sciences and then it has been tested under industrial conditions. The design makes provision for retention of the conveyor belt at its reverse motion beyond free edges from transported material. Catching devices are installed on both sides of the belt. Braking action of the belt at the reverse motion occurs due to its friction interaction with a catcher friction shoe located above the belt, and an eccentric mounted on the frame under the belt. A friction shoe is made with a concave curved surface facing the belt. The paper presents a calculation methodology of main parameters for the proposed design of catcher conveyor belts that permits to determine a force catching a conveyor belt down and for every braking period distance which has been passed by the belt, value of its compression, value of braking force, braking time and acceleration of belt motion, time and length of the distance passed by the belt to its full stop, parameters of a catcher and supporting structures, and other parameters. The paper also provides results of calculations for main design parameters of catching devices with an inclined conveyor having a belt width of 1400 mm for two catcher design versions: with location of an eccentric under the belt, and a brake shoe over the belt (option I) and with location of the eccentric over the conveyor belt, and the brake friction shoe under the belt (option II).



2018 ◽  
Vol 48 (8) ◽  
pp. 1364-1383 ◽  
Author(s):  
Gabriel Fedorko ◽  
Vieroslav Molnár ◽  
Peter Michalik ◽  
Miroslav Dovica ◽  
Tatiana Kelemenová ◽  
...  

This paper is dedicated to investigating the properties of smooth conveyor belts through a tensile loading test, with the aim of examining the behavior of the inner structure of the belt samples. When the belt is subjected to a long-term strain, the belt relaxation effect is observed and changes may occur to the inner structure of the belt. The tensile test at constant velocity determines the load strength limit of the strip samples. The experiment has also shown the phenomenon of relaxation of the samples after the load. Metro-tomographic analysis is used to observe the behavior of the internal structure of the belt sample after the load. The obtained results indicate the initial damage of the inner structure of the conveyor belt occurred at the value of 2157 N. Under this load, the maximum damage size was 4.8 mm. This confirms the suitability of the method for tracking changes in the internal structure.



1976 ◽  
Vol 19 (3) ◽  
pp. 373-374 ◽  
Author(s):  
James A. Schafer

Let T2 = S1×S1, where S1 is the unit circle, and let {α, β} be the integral basis of H1(T2) induced by the 2 S1-factors. It is well known that 0 ≠ X = pα + qβ is represented by a simple closed curve (i.e. the homotopy class αppq contains a simple closed curve) if and only if gcd(p, q) = 1. It is the purpose of this note to extend this theorem to oriented surfaces of genus g.



2019 ◽  
Vol 9 (7) ◽  
pp. 1304
Author(s):  
Luis Carretero ◽  
Pablo Acebal ◽  
Salvador Blaya

A numerical analysis is carried out of the influence of the de-phasing parameter of anoptical conveyor belt in the enantiomeric separation. The optical conveyor belt is obtained by theinterference of a Laguerre Gaussian and a Gaussian beam with different beam waists, which aretemporally de-phased. In order to obtain the maximum separation distance between enantiomers,we calculate the optimum range of values of the de-phasing parameter.



1960 ◽  
Vol 12 ◽  
pp. 209-230 ◽  
Author(s):  
R. H. Bing

One of the unsolved problems of plane topology is the following:Question. What are the homogeneous bounded plane continua?A search for the answer has been punctuated by some erroneous results. For a history of the problem see (6).The following examples of bounded homogeneous plane continua are known : a point; a simple closed curve; a pseudo arc (2, 12); and a circle of pseudo arcs (6). Are there others?The only one of the above examples that contains an arc is a simple closed curve. In this paper we show that there are no other such examples. We list some previous results that point in this direction. Mazurkiewicz showed (11) that the simple closed curve is the only non-degenerate homogeneous bounded plane continuum that is locally connected. Cohen showed (8) that the simple closed curve is the only homogeneous bounded plane continuum that contains a simple closed curve.



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