scholarly journals Strengths and weaknesses of the logistic function used in forecasting

2021 ◽  
Author(s):  
THEODORE MODIS
Keyword(s):  
Growth Cycle ◽  
Logistic Function ◽  
Point Of View ◽  
Time Data ◽  
Practical Point ◽  
Four Seasons

This work describes strengths and weaknesses of the logistic function used in forecasting from a theoretical and a practical point of view. Theoretical topics treated are: generalizing the concept of competition, dividing the growth cycle in four "seasons", and using logistics simply qualitatively to obtain rare insights and intuitive understanding. Practical topics addresses are: determination of the uncertainties, how to decide whether to fit cumulative or per unit of time data, and how to deal with a bias toward a low ceiling.

scholarly journals Determination of Odor Intensity of Binary Gas Mixtures Using Perceptual Models and an Electronic Nose Combined with Fuzzy Logic

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3473 ◽  
Author(s):  
Szulczyński ◽  
Gębicki
Keyword(s):  
Fuzzy Logic ◽  
Point Of View ◽  
Odor Intensity ◽  
Gas Mixture ◽  
Electronic Noses ◽  
Practical Point ◽  
Fuzzy Logic Algorithm ◽  
Holistic Analysis ◽  
Analyze Data

Measurement and monitoring of air quality in terms of odor nuisance is an important problem. From a practical point of view, it would be most valuable to directly link the odor intensity with the results of analytical air monitoring. Such a solution is offered by electronic noses, which thanks to the possibility of holistic analysis of the gas sample, allow estimation of the odor intensity of the gas mixture. The biggest problem is the occurrence of odor interactions between the mixture components. For this reason, methods that can take into account the interaction between components of the mixture are used to analyze data from the e-nose. In the presented study, the fuzzy logic algorithm was proposed for determination of odor intensity of binary mixtures of eight odorants: n-Hexane, cyclohexane, toluene, o-xylene, trimethylamine, triethylamine, α-pinene, and β-pinene. The proposed algorithm was compared with four theoretical perceptual models: Euclidean additivity, vectorial additivity, U model, and UPL model.

scholarly journals Proposal for the Evaluation of the Stability Level of Periodic Timetable in Terms of Operation and Infrastructure

2021 ◽  
Vol 17 (1) ◽  
pp. 25-33
Author(s):  
Lukáš Čechovič ◽  
Adrián Šperka ◽  
Jozef Gašparík
Keyword(s):  
Rail Transport ◽  
Point Of View ◽  
Passenger Transport ◽  
Railway Transport ◽  
Scientific Methods ◽  
Practical Point ◽  
Railway Networks ◽  
Transport Path ◽  
The Stability

Abstract The introduction of tact timetable in rail passenger transport is currently a new evolving trend that increases the efficiency of rail transport. This article seeks to contribute in this area of the issue and thus to raise and improve this system of organizing transport in railway transport. The aim is to propose a methodology that assesses the level of stability of tact timetable based on operational and infrastructural factors. The methodology identifies operational-infrastructural factors that affect the stability and reliability of tact timetable. Using scientific methods, it presents the method of their quantification and determination of the weights of these factors, which evaluate the line sections and transport points of the examined transport path. From a practical point of view, the methodology is generally tact applicable to other European railway networks. In the final part of the work, this methodological procedure is applied in the form of model examples for various transport path.

scholarly journals A Faster Tree-Decomposition Based Algorithm for Counting Linear Extensions

Algorithmica ◽  
2019 ◽  
Vol 82 (8) ◽  
pp. 2156-2173 ◽  
Author(s):  
Kustaa Kangas ◽  
Mikko Koivisto ◽  
Sami Salonen
Keyword(s):  
Point Of View ◽  
The Other ◽  
Tree Decomposition ◽  
Statistical Regression ◽  
Linear Extensions ◽  
Time Data ◽  
Practical Point ◽  
Running Time ◽  
Fast Multiplication ◽  
Cover Graph

Abstract We investigate the problem of computing the number of linear extensions of a given n-element poset whose cover graph has treewidth t. We present an algorithm that runs in time $${\tilde{O}}(n^{t+3})$$ O ~ ( n t + 3 ) for any constant t; the notation $${\tilde{O}}$$ O ~ hides polylogarithmic factors. Our algorithm applies dynamic programming along a tree decomposition of the cover graph; the join nodes of the tree decomposition are handled by fast multiplication of multivariate polynomials. We also investigate the algorithm from a practical point of view. We observe that the running time is not well characterized by the parameters n and t alone: fixing these parameters leaves large variance in running times due to uncontrolled features of the selected optimal-width tree decomposition. We compare two approaches to select an efficient tree decomposition: one is to include additional features of the tree decomposition to build a more accurate, heuristic cost function; the other approach is to fit a statistical regression model to collected running time data. Both approaches are shown to yield a tree decomposition that typically is significantly more efficient than a random optimal-width tree decomposition.

scholarly journals Determination of Ranges of Components of Heat Affected Zone Including Changes of Structure / Określenie Zakresów Składowych Strefy Wpływu Ciepła Uwzględniając Zmiany Struktury

2015 ◽  
Vol 60 (4) ◽  
pp. 2607-2612 ◽  
Author(s):  
Z. Śloderbach ◽  
J. Pająk
Keyword(s):  
Creep Strength ◽  
Thermal Fatigue ◽  
Heat Affected Zone ◽  
Analytical Method ◽  
Structural Changes ◽  
Point Of View ◽  
Practical Point ◽  
Fine Grained ◽  
Welding Technology

A simplified analytical method to determine the range of the heat affected zone and its components during welding is presented. Heat affected zone (HAZ) is an area formed during welding in which, as the result of temperature, some structural changes in the welded material occured. Knowledge of the area and sub-areas of HA Z is important from practical point of view, since the area of the fine-grained HAZ is a critical place in terms of creep strength and thermal fatigue. Heat affected zone is often the cause of future damage of many devices in which welding technology was used for their repair.

scholarly journals Some Peculiarities of the Process of Preparing the Zeolites Containing Breeds in a Ball Mill

2019 ◽  
Vol 8 (4) ◽  
pp. 7695-7698
Keyword(s):  
Energy Consumption ◽  
Ball Mill ◽  
Point Of View ◽  
Specific Productivity ◽  
Grinding Process ◽  
Ball Mills ◽  
Practical Point ◽  
Grinding Conditions

The article presents the results of studies of grindability of zeolite-containing rocks in ball mills with different grinding conditions. The results of studies of grindability of zeolite-containing rocks, optimization of the grinding process and determination of the specific productivity of industrial mills are presented. From a practical point of view, the data obtained can reduce the energy consumption of the grinding process of zeolite-containing rocks and increase the values of equipment efficiency and improve the quality of the finished product.

Tertiary Nitrification Pilot Plants on Parisian Waste Water

1990 ◽  
Vol 22 (1-2) ◽  
pp. 347-352 ◽  
Author(s):  
C. Paffoni ◽  
B. Védry ◽  
M. Gousailles
Keyword(s):  
Waste Water ◽  
Metropolitan Area ◽  
Fixed Bed ◽  
Point Of View ◽  
Operating Conditions ◽  
Research Center ◽  
Daily Output ◽  
Practical Point ◽  
Fixed Bed Reactors

The Paris Metropolitan area, which contains over eight million inhabitants, has a daily output of about 3 M cu.meters of wastewater, the purification of which is achieved by SIAAP (Paris Metropolitan Area Sewage Service) in both Achères and Valenton plants. The carbon pollution is eliminated from over 2 M cu.m/day at Achères. In order to improve the quality of output water, its tertiary nitrification in fixed-bed reactors has been contemplated. The BIOFOR (Degremont) and BIOCARBONE (OTV) processes could be tested in semi-industrial pilot reactors at the CRITER research center of SIAAP. At a reference temperature of 13°C, the removed load is approximately 0.5 kg N NH4/m3.day. From a practical point of view, it may be asserted that in such operating conditions as should be at the Achères plant, one cubic meter of filter can handle the tertiary nitification of one cubic meter of purified water per hour at an effluent temperature of 13°C.

scholarly journals On the Design of Outdoor Leader-Follower UAV-Formation Controllers from a Practical Point of View

IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Lucas Vago Santana ◽  
Alexandre Santos Brandao ◽  
Mario Sarcinelli-Filho
Keyword(s):  
Point Of View ◽  
Practical Point

scholarly journals Evaluation of the Ability to Accurately Produce Angular Details by 3D Printing of Plastic Parts

Machines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 150
Author(s):  
Andrei Marius Mihalache ◽  
Gheorghe Nagîț ◽  
Laurențiu Slătineanu ◽  
Adelina Hrițuc ◽  
Angelos Markopoulos ◽  
...  
Keyword(s):  
3D Printing ◽  
Point Of View ◽  
Vertex Angle ◽  
Function Type ◽  
Constant Height ◽  
3D Printers ◽  
3D Printed ◽  
Mathematical Processing ◽  
Plastic Parts

3D printing is a process that has become widely used in recent years, allowing the production of parts with relatively complicated shapes from metallic and non-metallic materials. In some cases, it is challenging to evaluate the ability of 3D printers to make fine details of parts. For such an assessment, the printing of samples showing intersections of surfaces with low angle values was considered. An experimental plan was designed and materialized to highlight the influence of different factors, such as the thickness of the deposited material layer, the printing speed, the cooling and filling conditions of the 3D-printed part, and the thickness of the sample. Samples using areas in the form of isosceles triangles with constant height or bases with the same length, respectively, were used. The mathematical processing of the experimental results allowed the determination of empirical mathematical models of the power-function type. It allowed the detection of both the direction of actions and the intensity of the influence exerted by the input factors. It is concluded that the strongest influence on the printer’s ability to produce fine detail, from the point of view addressed in the paper, is exerted by the vertex angle, whose reduction leads to a decrease in printing accuracy.

Determination of a Rubber-Like Material Model as an Inverse Problem

2011 ◽  
Vol 70 ◽  
pp. 225-230 ◽  
Author(s):  
Agnieszka Derewonko ◽  
Andrzej Kiczko
Keyword(s):  
Selection Process ◽  
Axial Stress ◽  
Constitutive Models ◽  
Material Model ◽  
Polyester Fabric ◽  
Point Of View ◽  
Air Cushion ◽  
Ill Conditioning ◽  
Stress States

The purpose of this paper is to describe the selection process of a rubber-like material model useful for simulation behaviour of an inflatable air cushion under multi-axial stress states. The air cushion is a part of a single segment of a pontoon bridge. The air cushion is constructed of a polyester fabric reinforced membrane such as Hypalon®. From a numerical point of view such a composite type poses a challenge since numerical ill-conditioning can occur due to stiffness differences between rubber and fabric. Due to the analysis of the large deformation dynamic response of the structure, the LS-Dyna code is used. Since LS-Dyna contains more than two-hundred constitutive models the inverse method is used to determine parameters characterizing the material on the base of results of the experimental test.

Resistance to Outflow of Cerebrospinal Fluid Determined by Bolus Injection Technique and Constant Rate Steady State Infusion in Humans

Neurosurgery ◽  
1985 ◽  
Vol 16 (3) ◽  
pp. 336-340 ◽  
Author(s):  
Michael Kosteljanetz
Keyword(s):  
Cerebrospinal Fluid ◽  
Steady State ◽  
Bolus Injection ◽  
Point Of View ◽  
Injection Technique ◽  
Communicating Hydrocephalus ◽  
Constant Rate ◽  
High Degree ◽  
Infusion Technique

Abstract Two methods for the determination of resistance to the outflow of cerebrospinal fluid, the bolus injection technique and the constant rate steady state infusion technique, were compared. Thirty-two patients with a variety of intracranial diseases (usually communicating hydrocephalus) were studied. There was a high degree of correlation between the resistance values obtained with the two methods, but values based on the bolus injection technique were systematically and statistically significantly lower than those obtained with the constant rate infusion test. From a practical point of view. both methods were found to be applicable in a clinical setting.

Sign in / Sign up

Export Citation Format

Share Document