scholarly journals Modelling of white bream (Blicca bjoerkna (Linnaeus, 1758)) commercial catches by different parameters of fishing gillnets in Kyiv Reservoir

2021 ◽  
pp. 5-17
Author(s):  
V. Lytvynenko ◽  
◽  
G. Kotovska ◽  
O. Buzevych ◽  
S. Kurhanskyi ◽  
...  
Keyword(s):  
Sustainable Use ◽  
Age Groups ◽  
Mesh Size ◽  
Commercial Fish ◽  
Weight Growth ◽  
Effective Removal ◽  
Proposed Model ◽  
The Mathematical Model ◽  
First Time ◽  
White Bream

Purpose. To analyze the existing experience in quantitative and qualitative modelling of commercial fish harvesting and to develop the methodological approaches in determining the optimal catch parameters for gillnets. Methodology. An adjusted annual commercial mortality rate was used to determine the catches composition in gillnets with different mesh sizes. Findings. The proposed model was developed within the framework of the generally accepted concept of population dynamics and biomass as a result of mortality and weight growth. It showed the dependence of the size-age structure and total weight of the catch on the mesh size of the grids. Originality of the work was caused by using the mathematical model that can ensure sustainable use of nature based on the optimal parameters of shutter grids on the possibility of their effective removal of certain age groups of white bream for the first time. Practical Value: calculations performed according to this model for the white bream of the Kyiv Reservoir showed that it is optimal to use grids with a mesh step of 40-50 mm, which allow to obtain the maximum catch per unit of replenishment and ensure high population fertility. Keywords: white bream (Blicca bjoerkna Linnaeus, 1758), Kyiv reservoir, commercial catches, modelling of catch.

scholarly journals An Optimized Mathematical Model for Items Supplies Planning of a Logistic System

2016 ◽  
Vol 10 (10) ◽  
pp. 133
Author(s):  
Mohammad Ali Nasiri Khalili ◽  
Mostafa Kafaei Razavi ◽  
Morteza Kafaee Razavi
Keyword(s):  
Mathematical Model ◽  
Mixed Integer ◽  
Logistics System ◽  
Proposed Model ◽  
Multiple Objective Decision Making ◽  
System Requirements ◽  
Purchasing Logistics ◽  
The Cost ◽  
The Mathematical Model ◽  
First Time

Items supplies planning of a logistic system is one of the major issue in operations research. In this article the aim is to determine how much of each item per month from each supplier logistics system requirements must be provided. To do this, a novel multi objective mixed integer programming mathematical model is offered for the first time. Since in logistics system, delivery on time is very important, the first objective is minimization of time in delivery on time costs (including lack and maintenance costs) and the cost of purchasing logistics system. The second objective function is minimization of the transportation supplier costs. Solving the mathematical model shows how to use the Multiple Objective Decision Making (MODM) can provide the ensuring policy and transportation logistics needed items. This model is solved with CPLEX and computational results show the effectiveness of the proposed model.

Innovations in Fishing Gear Design Aiming at the Sustainable Use of Commercial Fish Stocks

2006 ◽  
Author(s):  
Erdmann Dahm
Keyword(s):  
Fishery Management ◽  
Sustainable Use ◽  
Mesh Size ◽  
Fish Stock ◽  
Fishing Gear ◽  
Commercial Fish ◽  
Fish Stocks ◽  
Gear Design ◽  
Ecological Changes ◽  
Open Shape

The present status of some of the fish stocks in North Sea and Baltic shows them to be outside safe biological limits. Reasons for this lie partly in hydrographic and ecological changes not in favour for a constant supply of fresh recruits to the fishery every year. On the other hand, fishery has its share in the observed downward trend by growth overfishing and reducing the size and number of possible spawners. The only mean available for the fishery management to restore a fish stock composed of several year classes is to apply technical measures as e.g.closures in space and time or fishing gear regulations. The breakdown of the historical measure “mesh size regulation in diamond mesh trawls” due to technological progress has created a wave of worldwide research. It has focused on trawl codends where the meshes are held artificially in their most open shape or by introducing into the trawl metal structures able to separate small from big fish or fish from crayfish. A parallel development of a scientifically objective mesh measuring instrument will help to enforce the new regulations. However, longer use of some of the new designs has revealed some deficiencies. Other innovative designs or the concept of certified codends will hopefully ensure the permanently better selectivity of contemporary trawl codends.

scholarly journals PECULIARITIES OF CULTIVATION OF THE ORANGE-FIN RAINBOW TROUT ONCORHYNCHUS MYKISS (WALBAUM, 1792) IN CONDITIONS OF THE SULAK CANYON

2019 ◽  
pp. 14-19
Author(s):  
Evgeny Nikolaevich Lobachev ◽  
Ruslan Magomedovich Barkhalov ◽  
Nukhkadi Ibragimovich Rabazanov ◽  
Umshanat Dzhamaldinovna Zurkhaeva
Keyword(s):  
Rainbow Trout ◽  
Average Weight ◽  
Commercial Fish ◽  
Spring Period ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Weight Growth ◽  
The Republic ◽  
First Time ◽  
Feed Coefficient

The article has, for the first time in 20 years, presented the data on weight growth of the rainbow trout, grown in cag-es, in the territory of the Republic of Daghestan. The experiment has been conducted on the 5000 fries of the rainbow trout with an average weight of 41 gr. throughout the spring period. Tested was the original feed of the simplified rec-ipes and the minimal equipment costs for its production. As a result, it was proved that in the territory of the Sulak canyon there are all opportunities for growing commercial fish in cages. The results of the study showed that by the end of the experiment, the average weight of rainbow trout fry had reached 80 gr., the feed coefficient was 0,57–0,60%, while the loss of the fry was not observed. That indicates good quality of the food and favorable natural conditions for growing fish.

MONITORING RESULTS OF SAZAN (CYPRINUS CARPIO CARPIO LINNAEUS, 1758) POPULATION IN THE EASTERN PART OF THE TAGANROG BAY AND THE DON RIVER DELTA

2020 ◽  
Author(s):  
P.A. Balykin ◽  
◽  
A.V. Startsev ◽  
G.E. Guskov ◽  
A.S. Grin ◽  
...  
Keyword(s):  
Age Groups ◽  
Indirect Evidence ◽  
Parasite Fauna ◽  
River Delta ◽  
Weight Growth ◽  
Younger Age ◽  
Cyprinus Carpio Carpio ◽  
Don River ◽  
Taganrog Bay ◽  
Biological State

The materials for 2003-2018 on the biological state of sazan of the eastern part of the Taganrog Bay and the Don River delta were summarized. It has been shown that the catches of sazan in the study area consisted of more than half of the fish of younger age groups, the length of which was less than the commercial measure. The ratio of linear and weight growth of sazan is shifting towards a decrease in the mass of one-dimensional specimen, which is indirect evidence of the deterioration of the natural living conditions of semi-migratory fish. In 2019, the carp parasite fauna was represented by 7 species related to monogenes - 2 species, cestodes - 3 species, nematodes - 1 species, crustaceans - 1. The state of the sazan population needs further research.

THE DEVELOPMENT OF THE MATHEMATICAL MODEL OF PREDICTING THE INDICATORS OF ACCREDITATION OF TECHNICAL UNIVERSITIES IN THE RUSSIAN FEDERATION

2017 ◽  
pp. 27-38
Author(s):  
Olga Mikhaylovna Tikhonova ◽  
Alexander Fedorovich Rezchikov ◽  
Vladimir Andreevich Ivashchenko ◽  
Vadim Alekseevich Kushnikov
Keyword(s):  
Mathematical Model ◽  
System Dynamics ◽  
Regression Model ◽  
Oriented Graph ◽  
Real Data ◽  
Educational Process ◽  
Proposed Model ◽  
Linear Differential ◽  
The University ◽  
The Mathematical Model

The paper presents the system of predicting the indicators of accreditation of technical universities based on J. Forrester mechanism of system dynamics. According to analysis of cause-and-effect relationships between selected variables of the system (indicators of accreditation of the university) there was built the oriented graph. The complex of mathematical models developed to control the quality of training engineers in Russian higher educational institutions is based on this graph. The article presents an algorithm for constructing a model using one of the simulated variables as an example. The model is a system of non-linear differential equations, the modelling characteristics of the educational process being determined according to the solution of this system. The proposed algorithm for calculating these indicators is based on the system dynamics model and the regression model. The mathematical model is constructed on the basis of the model of system dynamics, which is further tested for compliance with real data using the regression model. The regression model is built on the available statistical data accumulated during the period of the university's work. The proposed approach is aimed at solving complex problems of managing the educational process in universities. The structure of the proposed model repeats the structure of cause-effect relationships in the system, and also provides the person responsible for managing quality control with the ability to quickly and adequately assess the performance of the system.

scholarly journals On the Dragging Trajectory of Anchors in Clay for Merchant Ships

2021 ◽  
Vol 9 (2) ◽  
pp. 118
Author(s):  
Xinqing Zhuang ◽  
Keliang Yan ◽  
Pan Gao ◽  
Yihua Liu
Keyword(s):  
Mathematical Model ◽  
Structural Integrity ◽  
Indirect Measurement ◽  
Test System ◽  
Flow Rule ◽  
Burial Depth ◽  
Proposed Model ◽  
Depth Increase ◽  
Two Parameters ◽  
The Mathematical Model

Anchor dragging is a major threat to the structural integrity of submarine pipelines. A mathematical model in which the mechanical model of chain and the bearing model of anchor were coupled together. Based on the associated flow rule, an incremental procedure was proposed to solve the spatial state of anchor until it reaches the ultimate embedding depth. With an indirect measurement method for the anchor trajectory, a model test system was established. The mathematical model was validated against some model tests, and the effects of two parameters were studied. It was found that both the ultimate embedding depth of a dragging anchor and the distance it takes to reach the ultimate depth increase with the shank-fluke pivot angle, but decrease as the undrained shear strength of clay increases. The proposed model is supposed to be useful for the embedding depth calculation and guiding the design of the pipeline burial depth.

scholarly journals Content Dependent Representation Selection Model for Systems Based on MPEG DASH

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1843
Author(s):  
Jelena Vlaović ◽  
Snježana Rimac-Drlje ◽  
Drago Žagar
Keyword(s):  
Mathematical Model ◽  
Spatial Information ◽  
Relevant Literature ◽  
Video Quality ◽  
Similarity Index ◽  
Video Encoding ◽  
Adaptation Algorithm ◽  
Subjective Testing ◽  
Proposed Model ◽  
The Mathematical Model

A standard called MPEG Dynamic Adaptive Streaming over HTTP (MPEG DASH) ensures the interoperability between different streaming services and the highest possible video quality in changing network conditions. The solutions described in the available literature that focus on video segmentation are mostly proprietary, use a high amount of computational power, lack the methodology, model notation, information needed for reproduction, or do not consider the spatial and temporal activity of video sequences. This paper presents a new model for selecting optimal parameters and number of representations for video encoding and segmentation, based on a measure of the spatial and temporal activity of the video content. The model was developed for the H.264 encoder, using Structural Similarity Index Measure (SSIM) objective metrics as well as Spatial Information (SI) and Temporal Information (TI) as measures of video spatial and temporal activity. The methodology that we used to develop the mathematical model is also presented in detail so that it can be applied to adapt the mathematical model to another type of an encoder or a set of encoding parameters. The efficiency of the segmentation made by the proposed model was tested using the Basic Adaptation algorithm (BAA) and Segment Aware Rate Adaptation (SARA) algorithm as well as two different network scenarios. In comparison to the segmentation available in the relevant literature, the segmentation based on the proposed model obtains better SSIM values in 92% of cases and subjective testing showed that it achieves better results in 83.3% of cases.

Loyalty program in Africa: risk-seeking and risk-averse adventurers

2014 ◽  
Vol 69 (2) ◽  
pp. 137-157 ◽  
Author(s):  
Shogo Mlozi
Keyword(s):  
Consumer Behavior ◽  
Consumer Products ◽  
Loyalty Programs ◽  
Risk Averse ◽  
Loyalty Program ◽  
Content Type ◽  
Risk Seeking ◽  
Proposed Model ◽  
First Time ◽  
The Relationship

Purpose – This article aims to test the relationship between expected attractiveness-satisfaction-loyalty for international adventure tourists visiting Tanzania. The proposed model is based on travel consumer behavior theoretical constructs extracted from the literature. Design/methodology/approach – This article aims to test the relationship between expected attractiveness-satisfaction-loyalty for international adventure tourists visiting Tanzania. The proposed model is based on travel consumer behavior theoretical constructs extracted from the literature. Findings – The findings for overall model differed from the moderating factors of high risk, low risk, first-time visit and repeat visit. Also, the results are interesting when satisfaction is tested as a mediator. Practical implications – Practitioners could consider the fact that repeat visits may change tourists’ perceptions toward destination and may even increase their inclination to take on risks. This may impact innovation of consumer products in tourism. Also, policy makers could benefit on how loyalty programs can be developed to increase performance. Originality/value – The study offers specific strategic recommendations toward different groups of tourists (i.e. first-time, repeat visitors, risk averse, risk seeking) and proposes logic for setting up a loyalty program as a long-term strategy for success.

Microhabitat use of different age groups of snake-eyed skink and Eastern green lizard

2016 ◽  
Vol 37 (2) ◽  
pp. 191-198 ◽  
Author(s):  
Dániel Kovács ◽  
István Kiss
Keyword(s):  
Habitat Management ◽  
Age Groups ◽  
Carpathian Basin ◽  
Microhabitat Use ◽  
Forest Edges ◽  
Environmental Niche ◽  
The Balkans ◽  
Natural Grasslands ◽  
Lacerta Viridis ◽  
First Time

Although Ablepharus kitaibelii and its subspecies are wide-spread, being distributed from the Carpathian Basin through the Balkans to Iraq, their habitat and environmental niche is poorly known. Ablepharus kitaibelii fitzingeri is almost entirely limited to the Carpathian Basin, and is amongst the most strictly protected and least known reptiles of Central and Eastern Europe. The main aim of our study was to determine habitat use preferences of different age groups of A. kitaibelii fitzingeri and Lacerta viridis. The occurrence of green lizard was determined by the abundance of refugia rather than by the naturalness of grasslands. The snake-eyed skink prefers semi-natural grasslands with abundant tussock-forming grass or sedge species, avoiding densely shrubby places. For the first time, we show that woodland mosaics lacking shrubs and temporary grasslands next to forest edges are important for the species. Microhabitat use by snake-eyed skink varies with age group; adults preferring shady edge zones rich in leaf litter and shadier grassland spots provided by woodland mosaics, whereas juveniles were found in natural, more open grasslands far from forest edges and in woodland mosaics with dense shrubby understory. Our results contribute to a better understanding of the ecological needs of A. kitaibelii fitzingeri. Our methodology could be adapted to other species and subspecies of Ablepharus. Based on our results, it is important to reconsider habitat management activities, which should not be limited to shrub control: the main goal should be the development of a diverse habitat structure.

scholarly journals How to evaluate sustainability of supply chains? A dynamic network DEA approach

2017 ◽  
Vol 117 (9) ◽  
pp. 1866-1889 ◽  
Author(s):  
Vahid Shokri Kahi ◽  
Saeed Yousefi ◽  
Hadi Shabanpour ◽  
Reza Farzipoor Saen
Keyword(s):  
Big Data ◽  
Supply Chains ◽  
Real World ◽  
Performance Optimization ◽  
Network Dynamic ◽  
Network Dea ◽  
Content Type ◽  
Dea Model ◽  
Proposed Model ◽  
First Time

Purpose The purpose of this paper is to develop a novel network and dynamic data envelopment analysis (DEA) model for evaluating sustainability of supply chains. In the proposed model, all links can be considered in calculation of efficiency score. Design/methodology/approach A dynamic DEA model to evaluate sustainable supply chains in which networks have series structure is proposed. Nature of free links is defined and subsequently applied in calculating relative efficiency of supply chains. An additive network DEA model is developed to evaluate sustainability of supply chains in several periods. A case study demonstrates applicability of proposed approach. Findings This paper assists managers to identify inefficient supply chains and take proper remedial actions for performance optimization. Besides, overall efficiency scores of supply chains have less fluctuation. By utilizing the proposed model and determining dual-role factors, managers can plan their supply chains properly and more accurately. Research limitations/implications In real world, managers face with big data. Therefore, we need to develop an approach to deal with big data. Practical implications The proposed model offers useful managerial implications along with means for managers to monitor and measure efficiency of their production processes. The proposed model can be applied in real world problems in which decision makers are faced with multi-stage processes such as supply chains, production systems, etc. Originality/value For the first time, the authors present additive model of network-dynamic DEA. For the first time, the authors outline the links in a way that carry-overs of networks are connected in different periods and not in different stages.

Sign in / Sign up

Export Citation Format

Share Document