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The number of microorganisms and chemical values of the milks separated according to their quality are different from each other. In case of mixing different quality types of milk, composed milk quality is considered equal to the lowest quality milk type among the types of milk added to the mixture. Therefore, different types of raw milk should not...
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... The solution is illustrated in Figure 1 as service network map and is shown in Table 3. The model was forced due to the 5500-liter milk supply in node 3 in the basic data set. ...Citations
... Çalışmadaki araç rotalama probleminin çözümü için matematiksel model hazırlanırken, literatürdeki kapasite kısıtlı araç rotalama problemleri için önerilen matematiksel modellerden esinlenilmiştir [23]. Bir araştırmada, araştırmacılar araçların kapasitelerini göz önünde bulunduran araç rotalama problemleri için hazırladıkları matematiksel modeli sunmuşlardır [24]. Başka bir çalışmada ise teslim alma ve teslim etme zamanlarını göz önünde bulunduran araç rotalama problemi matematiksel model çalışması yapılmıştır [25]. ...
... Ayrıca ana depodan ara depolara rotalama probleminin matematiksel modelinde kullanılan Denklem (8)'deki 0 değişkeninin ilk indis değeri 0, ara depodan merkezlere araç rotalama problemi için merkezlerin bağlı olduğu ara depoyu temsil edecek şekilde güncellenmiştir. Son olarak Denklem (24) olarak ifade edilen yeni kısıt ve kısıtın gerektirdiği yeni parametreler bir önceki problemden farklı olarak bu problemde matematiksel modele eklenerek ara depodan merkezlere araç rotalama probleminin çözümünde kullanılmıştır. ...
... Dairy farmers deal with specific features of milk production which make them sensitive to market disturbances. Their commodity is perishable, elasticity of farm milk supply is low (Hoehl 2020), farmers are usually not independent in milk collection (Polat et al. 2019) and still more factors weaken the dairy farmers' market positions. For farmers who do not actively participate in the sale of their products, in terms of either capital or organisation, the successful marketing of their production depends on downstream agents. ...
The standard economic price theory of working with efficient source allocation is being confronted with a series of empirical findings of asymmetric price responses. The objective of the research was to examine whether the distribution of prices within the dairy chain in the Czech Republic was fair and whether farmers progressed in a collective approach to strengthen their position in the supply chain. We used the pre-cointegration and cointegration approach to test for asymmetry in the transmission of farm milk prices throughout the supply chain. Furthermore, we measured the development of market concentration by means of the Herfindahl-Hirschman index and discussed the background of the figures with producer organisation representatives. The results proved there were asymmetric price transmissions. In response, farmers consolidated and concentrated their milk sales. The concentration should not yet be understood as a goal but as a means to the next steps.
The milk collection problem (MCP) is concerned with the collection of raw milk of varying quality at dairy factories via tankers under problem-specific constraints. During this collection process, keeping milk of different levels of quality separate is at least as critically important as production quality because when the milk of different qualities is mixed together, the worst quality determines the final milk quality. In MCP, decisions such as which farms/milk collection centers, quality of milk, types of tankers, storage tanks, and visiting sequences will be used are made. In this study, an integrated mathematical model is proposed for the first time that aims to minimize the total distance and total network costs for tanker assignments and routing problems by simultaneously considering realistic routing, incompatibility, and loading constraints. The problem was formulated as a mixed-integer linear program and the small instances were solved using CPLEX. To solve the larger-scale real-life problems, a variable neighborhood search (VNS) metaheuristic optimization framework is developed. The proposed mathematical model and the VNS framework were evaluated on scenarios based on real-life data from a dairy company. Computational results show that the proposed VNS framework solves the realistic MCP problem efficiently.
