فصلنامه کهربا
سال دوازدهم شماره 42 (زمستان 1402)

During the past years, many efforts have been made to reduce the cost of transportation by using different models of the vehicle routing problem; In fact, the increase in transportation costs has encouraged many to reduce the cost of transportation associated with their profession by utilizing a vehicle routing system. In this research, the problem of transportation routing in the supply chain for 40 nodes has been investigated; The problem of routing vehicles that depart from warehouses, meet a group of customers and return to the warehouse. Each vehicle has a fixed capacity and each customer has a specific demand that must be fully satisfied. The problem consists of combining meeting selection for each customer and determining vehicle routes based on the rules of the vehicle routing problem; So that the total distance traveled by each vehicle and the total times of early and late arrivals and the total total cost are minimized. Since the vehicle routing problem is a problem belonging to the NP-Hard class, the vehicle routing problem (VRP) is one of the complex problems belonging to the NP-Hard class, and meta-heuristic approaches are used to solve it. In this work, the genetic algorithm has been proposed to solve the vehicle routing problem and it has been tried to solve it using MATLAB software and achieve the optimal solution.

The purpose of this article is to present a comprehensive strategy to analyze and improve power quality issues according to possibilities and limitations. The strategy presented in this article is based on the results of the power quality measurement project in Semnan regional electricity transmission and super distribution networks in low load and high load) so that it can be used by experts in the electricity industry while presenting a practical case. In this article, an attempt has been made to examine the challenges and issues that exist in different stages of power quality studies (monitoring, analysis and corrective measures) in a real environment, and to provide a method and algorithm for a comprehensive study of power quality with the available facilities.

In the electric energy market, price is the most important signal for all generating units (GenCos). Each GenCo seeks a price offer that maximizes its profit. Therefore, in this article, a new educational algorithm based on the intelligentization of GenCos pricing is presented in order to learn the optimal strategy of GenCos and reach the Nash equilibrium point. In the meantime, the independent market operator (ISO) also establishes the balance by applying network restrictions. In order to investigate the effect of the adopted strategy on the state of market competition, we used the entropy coefficient index. The value of this index at the end of the work shows that GenCos have been able to increase their profits and monopolize the market more in the state without considering the permitted range of production and transmission compared to the state with the permitted range of production and transmission. The simulation results show the effectiveness of the proposed learning algorithm. The studied network is taken from the Nord Pool market

In this research and article, carbon materials were synthesized by arc discharge with different discharge parameters and analyzed. These materials are composed of soot globules with an irregular carbon structure, and there are also pieces of graphene in the material. Nevertheless, the electrical conductivity of the synthesized carbon materials is mainly determined by the contact resistance effect that appears due to the amorphous carbon covering the graphene particles. Depending on the synthesis conditions, the electrical conductivity has values in the range of 10-3 to 5.3 siemens/m. For synthesized materials containing graphene sheets with sizes larger than most carbon black globules, the electrical conductivity is determined by the content ratio of graphene sheets and carbon black globules. This material has an electrical conductivity of 33 xinmes per meter

Web engineering is a relatively new discipline in the field of software engineering. This article describes the specific features of web applications and different web engineering methods for developing web applications. Based on the investigations carried out on the WebSys project, some suggestions related to how to develop web engineering methods are presented.

Photonic crystal fibers (PCFs) are advanced technologies in the field of biomedical optics, extensively used in various scientific disciplines, including medicine and medical engineering. These fibers utilize crystal structures to guide light, enabling high sensitivity and accurate transmission of optical information for bioluminescent applications. PCFs have gained significant attention in biosensor development due to their unique optical properties, such as tunable structure and engineered dispersion. In this review, we investigate the applications of photonic crystal fibers in medicine, medical engineering, and other scientific fields. Additionally, we discuss the advantages and disadvantages of utilizing these fibers and provide suggestions to enhance future applications.