本文選題：物流企業(yè) + 運輸成本��； 參考：《華北電力大學(xué)》2014年碩士論文

【摘要】：隨著科學(xué)技術(shù)的發(fā)展,通過提高產(chǎn)品性能和勞動生產(chǎn)率來提高企業(yè)的利潤變得越來越困難。在追求最大利潤目標(biāo)的驅(qū)動下,人們發(fā)現(xiàn)物流占企業(yè)成本的較大比例,而通過優(yōu)化供應(yīng)鏈的某一環(huán)節(jié)可以大大降低物流成本。為了在競爭日益激烈的商品市場上獲得優(yōu)勢,企業(yè)對物流的優(yōu)化研究迅速發(fā)展起來。本文通過對物流企業(yè)的物流成本組成部分進(jìn)行分析發(fā)現(xiàn)：物流企業(yè)運輸成本占企業(yè)總成本很大比例。因此對物流企業(yè)運輸成本優(yōu)化問題研究具有較強(qiáng)的理論價值和現(xiàn)實意義。 物流企業(yè)的運輸成本不僅與車輛運輸過程中發(fā)生的固定成本和變動成本有關(guān),而且運輸時間的時間窗約束也會影響到運輸成本。物流企業(yè)根據(jù)客戶提出的時間窗約束支付相應(yīng)的懲罰費用,從而引起運輸成本的增加。時間窗可以分成軟時間窗、硬時間窗和混合時間窗三種。在實際的運輸過程中客戶對運輸時間的要求一般都是彈性的,因此本文選取軟時間窗為研究對象。但是,現(xiàn)有關(guān)于時間窗運輸成本優(yōu)化研究的文獻(xiàn)中忽略了一種現(xiàn)象：車輛在運輸過程中由于路況或人為因素會發(fā)生運輸中斷,從而造成運輸時間延長,即時間轉(zhuǎn)換約束。由于忽略了時間轉(zhuǎn)換約束的影響,進(jìn)而造成了物流企業(yè)決策者對運輸時間預(yù)測的誤差。因此,對考慮時間轉(zhuǎn)換約束運輸成本模型的研究能夠更好地反映實際運輸過程。 本文針對現(xiàn)有文獻(xiàn)中關(guān)于考慮時間窗約束的運輸成本模型研究的難點和不足,首先從時間窗的分類進(jìn)行分析,確定不同時間窗的適用范圍。然后,將項目網(wǎng)絡(luò)研究中的時間轉(zhuǎn)換約束引入運輸問題。針對這一問題,本文在所建立的考慮時間窗約束下運輸成本模型基礎(chǔ)上,加入了時間轉(zhuǎn)換約束。通過對兩個模型的分析發(fā)現(xiàn),時間轉(zhuǎn)換約束對物流企業(yè)運輸成本的影響不容忽視。在建模的過程中考慮到物流企業(yè)車輛數(shù)也是影響其運輸成本的重要因素,因此本文以運輸成本最小和物流企業(yè)自有車輛最小作為模型的兩個目標(biāo),進(jìn)而構(gòu)建了兩個雙目標(biāo)模型,并設(shè)計了改進(jìn)的遺傳算法來求解該雙目標(biāo)非線性問題。最后,通過S物流企業(yè)某次運輸過程驗證該算法的可行性和有效性。 在上述研究的基礎(chǔ)上,本文進(jìn)一步研究了時間轉(zhuǎn)換約束對物流企業(yè)運輸成本產(chǎn)生的影響。通過實例測試發(fā)現(xiàn)：(1)由于時間轉(zhuǎn)換約束的影響,實際運輸過程中產(chǎn)生的成本要高于以往傳統(tǒng)運輸成本模型下的計算結(jié)果；(2)時間轉(zhuǎn)換約束改變了物流企業(yè)的最優(yōu)運輸路徑。因此,在運輸成本優(yōu)化問題中考慮時間轉(zhuǎn)換約束的影響對物流企業(yè)有效管理有重要意義。
[Abstract]:With the development of science and technology, it is more and more difficult to improve the profit of enterprises by improving the product performance and labor productivity. Driven by the pursuit of the goal of maximum profit, it is found that logistics accounts for a large proportion of the cost of the enterprise, and logistics costs can be greatly reduced by optimizing a certain part of the supply chain. In order to gain advantage in the increasingly competitive commodity market, the research on logistics optimization has developed rapidly. By analyzing the logistics cost components of logistics enterprises, it is found that the transportation cost of logistics enterprises accounts for a large proportion of the total cost of enterprises. Therefore, the research on logistics enterprise transportation cost optimization has strong theoretical value and practical significance. The transportation cost of logistics enterprise is not only related to the fixed cost and variable cost in the course of vehicle transportation, but also the time window constraint of transportation time will affect the transportation cost. The logistics enterprises pay the penalty according to the time window proposed by the customer, which results in the increase of the transportation cost. Time window can be divided into soft time window, hard time window and mixed time window. In the actual transportation process, the customer's request for transportation time is generally elastic, so the soft time window is chosen as the research object in this paper. However, a phenomenon has been neglected in the literature on the optimization of transportation cost in time windows: the transportation interruption may occur in the course of vehicle transportation due to road conditions or human factors, which results in the prolongation of transportation time, that is, the constraint of time conversion. Because of neglecting the influence of time conversion constraint, the decision maker of logistics enterprise makes the error of transportation time prediction. Therefore, the research on the transport cost model with time conversion constraints can better reflect the actual transportation process. Aiming at the difficulties and shortcomings of the research on transportation cost model with time window constraints in the existing literature, this paper first analyzes the classification of time windows and determines the applicable scope of different time windows. Then, the time conversion constraints in the project network research are introduced into the transport problem. In order to solve this problem, the time conversion constraint is added to the transport cost model considering the time window constraint. Through the analysis of the two models, it is found that the influence of time conversion constraints on transportation cost of logistics enterprises can not be ignored. In the process of modeling, it is considered that the number of vehicles in logistics enterprises is also an important factor affecting their transportation cost. Therefore, this paper takes the minimum of transportation cost and the minimum of owned vehicles of logistics enterprises as the two objectives of the model, and then constructs two double-objective models. An improved genetic algorithm is designed to solve the two-objective nonlinear problem. Finally, the feasibility and effectiveness of the algorithm are verified by a transportation process in S logistics enterprise. On the basis of the above research, this paper further studies the influence of time conversion constraints on transportation costs of logistics enterprises. It is found that the cost in the actual transportation process is higher than that in the traditional transportation cost model because of the influence of the time conversion constraint) the time conversion constraint changes the optimal transportation path of the logistics enterprise. Therefore, it is important for logistics enterprises to consider the influence of time conversion constraints in transportation cost optimization.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：F253.7;F259.23

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