درخت حوزه‌های تخصصی

Perishable items such as dairy products, food and medicine, various vegetables, flowers and plants, ready-mix concrete, and blood packages typically have a limited shelf life from production to delivery and can deteriorate over time. To prevent such perishability, these types of products must be delivered to consumers promptly to ensure that the benefits of the producer and distributor are met. One effective factor in delivering various products to the consumer on time is selecting the optimal route for delivering goods or products, which is referred to as the problem of vehicle routing. Vehicle routing for distributing various goods and products is one of the practical issues in the field of research in operations that are very efficient in logistics planning. The objective of this problem is to determine the operational plan of the target vehicles with limited capacity for sending goods and products from the central warehouse depot to a group of consumers that are geographically dispersed in such a way that the number of required vehicles and travel costs are minimized. Considering that the issue mentioned is a very complex problem and it is not possible to find a high-quality answer with accurate methods in a short time for its large scale, the GAMS software has been used to solve this model on a smaller scale. Finally, to demonstrate the practical application of the proposed model in the real world, the distribution of products among customers in the Ports and Maritime Organization of Guilan Province (Bandar-e Anzali) has been studied. The computational results show that distributors can reduce their operational costs by using this approach.

Background and Theoretical Foundations: The environment problems have pervasive and lasting consequences for this generation and the next generation. The effects of environmental change on human life will soon appear. One of the most important environmental crises that Iran and the four littoral Caspian Sea countries bordering are facing is the environmental crisis of this sea. The Caspian Sea, the world's largest salt lake, has a sensitive ecosystem. Although salt lakes are very important for the environment, the most important example that has been recorded of the successful management of salt lakes is the case of the Great Lakes between the United States and Canada. Their solution can be used to protect the environment of these lakes in the Caspian Sea and its border countries.Method: In this research, by using the descriptive-analytical method, it has been tried to study the ecosystem of the Caspian Sea and find the best solution for it as a salt lake.Findings: As a matter of fact, although the Caspian Sea has a very rich resource but it has a very sensitive ecosystem and riparian states put it under pressure by over-exploitation of its resource. It caused several problems, such as degradation of water level, pollution of water, and the demise of caviar fish.Conclusion: It is extremely important to accurately attribute the causes of such change to understand how best to manage this body of water. In my opinion, Iran must pay more attention to its water in the north unless we face fine dust and drying of wetlands as we have seen in the south that put in danger human security in different dimensions.  It is undeniable that principles and obligations of international law such as paying polluters, common and differentiated responsibility, and non-harmful use of land… can’t solve the problems all alone. It is true about politics, but together, we can hope for sustainable management of the Caspian Sea. So the only way is the combination of international law and political will and using other states' experiences. So the proposal of this paper is building an institution with real decision-making. The design of the new institution is a step forward. For example, an institution can evaluate any problems with the Caspian Sea or rise by any coastline states and provide a solution, establishing a formal arrangement with real decision-making authority and not leaving most decisions up to individual states without effective collective control. However, in practice, states hardly show interest in institutions with mandatory power. So, instead, the Caspian Sea shoreline’s states can establish a non-mandatory committee that we hope to execute its decision with political will as we have seen in the Great Lakes. Because above all of this, politics will stand. So political and international law together could solve this problem.