Minimal KCKC-spaces are countably compact

summary:In this paper we show that a minimal space in which compact subsets are closed is countably compact. This answers a question posed in [1]

Minimizing WIP inventory in reliable production lines

This work deals with the well-known buffer allocation problem in short reliable production lines. The objective is to find the optimal buffer allocation (OBA) that minimizes the average work-in-process (WIP) inventory, subject to a minimum required throughput. The study leads to some insights concerning the evolution of the throughput and WIP as a function of the ordered buffer allocations. In the case of balanced lines, it is observed that the so-called self-similarity phenomenon prevails. It is also pointed out that the choice of the throughput level is critical for finding the OBA that minimizes the average WIP. Also a heuristic algorithm is proposed to find the OBA, which reduces the search space by over 50% compared to enumeration. (C) 2001 Elsevier Science B.V. All rights reserved

A heuristic algorithm for the buffer allocation in unreliable unbalanced production lines

In this work we investigate the buffer allocation problem (BAP) in short unbalanced production lines consisting of up to six machines that are subject to breakdowns. Times to failure are assumed exponential whereas service and repair times are allowed to follow any Erlang-k distribution (with k greater than or equal to 1). An algorithm that is based on the sectioning (segmentation) approach was developed which solves the BAP. This, in conjunction with a method not previously reported that determines a "good" initial solution for the buffer allocation constitutes the main contribution of the present work. The accuracy of the proposed heuristic algorithm is remarkably good and its convergence is fast making it a promising tool that can be implemented in conjunction with a fast decomposition method to solve the BAP in large production lines. (C) 2001 Elsevier Science Ltd. All rights reserved

Non-Archimedean Sequential Spaces And The Finest Locally Convex Topology With The Same Compactoid Sets

. For a non-Archimedean locally convex space (E; ø ), the finest locally convex topology having the same as ø convergent sequences and the finest locally convex topology having the same as ø compactoid sets are studied. Introduction For a locally convex space E over the field of either the real numbers or the complex numbers, Webb investigated in [13] the finest locally convex topology on E having the same convergent sequences as the original topology. Also, he studied the finest locally convex topology which has the same precompact sets. In this paper we look at analogous problems for non-Archimedean spaces. For a non-Archimedean locally convex space (E; ø ), we study the sequential locally convex topology ø s which is the finest locally convex topology with the same as ø convergent sequences. Passing from ø to ø s , we get that the category of nonArchimedean sequential locally convex spaces and continuous linear maps is a full coreflective subcategory of the category of all lo..

Environmental issues of aquaculture development

This article is addressing the issue of aquaculture generated pollution and the need to monitor and control this problem at the international level. The rapid global expansion of intensive aquaculture production creates conditions in which farmed fish can be constantly exposed to pathogens and the use of chemicals such as antibiotics, antifoulants, and disinfectants are regularly required. The global aquaculture growth and intensification of the production method were accompanied by the increased use of therapeutics and antibiotics which as in other agricultural sectors were embraced as the effective way of treating diseases and controlling pathogens and consequently some of the chemicals used in Aquaculture are extremely valuable and required for the welfare and the economic viability of the sector. Antifoulants and disinfectants can be released in the aquatic ecosystem. These chemicals are under scrutiny and some are banned for use in European countries. Depending on the methods of administering antibiotics and therapeutics as well as their elimination from the body, these compounds have played a role in the environmental pollution in different ways. The Aquaculture sector can thrive under conditions of water quality which ensures the optimal ecological parameters for the growing fish. Aquaculture is incompatible with environmental degradation, consequently, aquaculture stakeholders are obliged to protect the surrounding aquatic ecosystem in order to ensure the sustainability of the sector. In fact, although aquaculture has been blamed for generating aquatic pollution, the reverse is frequently observed for example when aquatic pollution from other sectors hinders aquaculture production and fisheries. © 2020, Egyptian Society for the Development of Fisheries and Human Health. All rights reserved