Abstract
Multi-objective optimization is an emerging field concerning optimization problems associated with more than one objective function, each of them has to be optimized simultaneously. Multi-objective optimization is widely used in logistics and supply chains to reduce the cost and time involved in transportation. With the increase in Global Supply Chains, many organizations are facing the challenges of delivering products to their customers at a fast pace, low cost, and high reliability. There are numerous factors that may affect the goal of an organization to optimize the cost, time, and effort during the transportation of their products to the end customers. For instance, in the existing transportation problems, the type of vehicles used for the movement of the products is not focused. Transportation of the goods is considered to utilize any type of vehicle irrespective of the nature of the goods. However, in real-life scenarios, there are certain constraints in the vehicle used to transport the finished goods or raw materials from a source to a destination. Vehicles such as tanker trucks, top open trucks, closed trucks, etc. need to be booked based on the nature of goods to be transported. Also, the cost and time of transportation are uncertain in nature. In this paper, we formulate the Multi-Objective Solid Transportation Problem (MOSTP) by considering the above issue. The uncertain parameters of the problem are considered as Pentagonal Intuitionistic Fuzzy Numbers (PIFN). Magnitude method is used for defuzzification. An algorithm to find the solution of formulated Intuitionistic Fuzzy Multi-Objective Solid Transportation problem (IFMOSTP) is provided. The proposed model is illustrated by a numerical example which is solved with the help of LINGO software.
Keywords
Abbreviations and notations
pentagonal intuitionistic fuzzy numbers
multi-objective solid transportation problems
intuitionistic fuzzy multi-objective solid transportation problems
solution of r th objective function
denotes the r th penalty criterion
denotes the number of objective considered
denotes the item of the goods to be transported
denotes the destination to which the goods to be transported
denotes type of vehicle used for transportation
is unit transportation penalty for i th item to j th destination through k th type of vehicle and is considered as PIFN
feasible solution for r th objective function
is the goods to be transported through k th means of transport to j th destination
is the demand in i th product to be transported through k th means of transport
is the i th product to be transported to the j th destination.
set of feasible solution for r th constraint
optimal solution for r th constraint
Introduction
One of the earliest applications of linear programming problems is the transportation problem. The transportation problem’s goal is to reduce the total cost of delivering a product from available sources or origin to the required destination. In 1941, Alfred Hitchcock [1] proposed the basic transportation problem. Appa [2] discussed variants of transportation problems. In 1963, Dantzig [3] developed an algorithm to solve transportation problems. Bridgen [4] presented an algorithm for solving the transportation problem, which includes equality and inequality constraints as well as availability constraints.
Shell [5] extended two-dimensional transportation problems to three-dimensional transportation problems, allowing for the consideration of three constraints. As an extension of the MODI method, Haley [6] created a solution procedure for solving solid transportation problems. He also extended solid transportation to multi-objective problems and illustrated the solution [7, 8]. In solid transportation problems, Patel and Tripathi [9] used mixed constraints. Lee and Moore [10] investigated the optimization of multi-objective transportation problems. Charnes and Cooper [11] proposed the goal programming method to solve multi-objective transportation problems. Ijiri [12], Lee [13], and others refined this technique. Bit et al, [14] proposed a fuzzy programming approach to multi-objective transportation problems in 1992. The aforementioned works were completed with precise parameters.
In real life situation due to various factors, the estimation of transportation cost, time, etc. are not precise in nature. To handle such situation Zadeh [15] introduced fuzzy sets. The idea of fuzzy sets was developed to handle uncertainty and vagueness which a simple crisp set cannot do. Attanassov [16] extended fuzzy sets to intuitionistic fuzzy sets which incorporated the value of hesitation to handle uncertainty efficiently. Intuitionistic fuzzy numbers [17] are special kind of intuitionistic fuzzy sets which are significant in solving linear programming problems. Intuitionistic fuzzy numbers can be expressed in the form of triangular, trapezoidal, pentagonal etc. Different form of uncertain parameter is discussed inTable 1. Because the parameters of MOSTP are uncertain in nature, many others have expressed an interest in solving such problems with uncertain parameters. Table 2 provides a literature review of various research studies conducted on MOSTP with uncertain parameters.
Different forms of parameters
Different forms of parameters
Literature review of multi-objective
Hassan Dalman, Sivri. M [36] in 2017 handled MOSTP by considering the parameters as interval numbers. The closed and bounded interval is converted into a deterministic one by using weighted factor that lies between [0, 1].The user may confuse while choosing the weighted factor. Also always it is not possible to say that cost lies within a single interval. Due to many factors there may be partition also. Li [31] solved MOSTP with fuzzy parameters using genetic algorithm. The availability is considered to be transported by all means of transportation. But this is not possible due to factor of such as availability of space in the vehicle, availability of routes, and nature of the goods to be transported. Mouhya [35] developed solution to multi-objective solid transportation problems in a fuzzy environment. The method followed to obtain crisp form is complicated and tedious. Trapezoidal fuzzy numbers used in this method can handle fewer factors than PIFN.
From the Table 2, it has been noticed that many works have been carried out to solve solid transportation problem and MOSTP in fuzzy environment. Only a few works have been carried out to solve solid transportation with intuitionistic fuzzy parameters. So, for in the literature, Multi-objective solid transportation with intuitionistic fuzzy parameters is not yet studied as a research paper. Hence the main purpose of this work is to study Multi-objective Solid transportation problem involving intuitionistic fuzzy numbers.
Novelty of the proposed work
In this work PIFN is used as parameters to handle uncertainty for the following factors: This number is created primarily to capture variations in the curve at different levels that a triangular and trapezoidal fuzzy number do not. The shape of pentagonal intuitionistic fuzzy numbers is simpler and more consistent, allowing for more natural interpretation and easier calculation. It is difficult to represent each parameter with triangular or trapezoidal intuitionistic fuzzy numbers if it has five variables. As a result, pentagonal intuitionistic fuzzy numbers can be used to solve the problem.
Motivation of the research work
During the actual transportation, the estimation done is not accurate, due to error in the measuring technique. Let us consider the transportation time of goods from the source to a destination to be ‘h’ hours approximately. (i.e.) it is not accurately ‘h’ hours.it is either less than ‘h’ hours or greater than ‘h’ hours. This concept of variation leads to a new type of IFN called PIFN. Generally, PIFN has five parameters for each membership and a non-membership function, which is a subset of real number
An IFN takes the form
where, the middle point a3 has the grade of membership 1. t and u are the grades of a2and a4 respectively.
For an instance, the time taken for transportation from Tirupur to Chennai is approximately 9 hours. It may be less than 9 hours or greater than 9 hours. This uncertainty may be due to the factors such as traffic, road condition, weather, vehicle efficiency etc. Considering the above factors time parameter can be represented as PIFN.
Transportation time is approximately 9 hours, hence a3 is 9 with membership grade 1. If the traffic is less than the time will reduce and is represented by giving weighted value ′t′ to a2. The time deviation due to less traffic is given by the interval [a2, a3]. If the traffic is heavy, then the time taken will increase. This is represented by giving a weighted value to ′u′ to a4. The time deviation due to more traffic is given by the interval [a3, a4]. The time delay due to weather condition is given in the interval [a4, a5]. The time deviation due road condition is given by the interval [a1, a2].
Structure of the paper
Section 2 contains preliminary definitions that is required to carry out the current research. Section 3 elaborates on the mathematical formation of intuitionistic fuzzy multi-objective solid transportation and the algorithm for obtaining the optimal solution. The proposed algorithm is validated in the following section by solving real-time problems in which the transportation parameters were modeled as pentagonal intuitionistic fuzzy numbers. Section 5 discusses the significance of the proposed research work in comparison to previous research. This paper concludes with a precise conclusion.
Preliminaries

Generalized non- symmetric pentagonal intuitionistic fuzzy number.
where
For an arbitrary Pentagonal intuitionistic fuzzy number
Magnitude of A [38] is given by
Where, the function r (y) is a non-negative and increasing function on [0,1] with r (0) = 0, r (1) = 1 and
The magnitude of non-symmetric Pentagonal intuitionistic fuzzy number is given by
For any two arbitrary Pentagonal intuitionistic fuzzy numbers
A ={ (a1, a2, a3, a4, a5) (b1, b2, b3, b4, b5) ; p, q, s, t } and
B ={ (c1, c2, c3, c4, c5) (d1, d2, d3, d4, d5) ; u, v, w, z }, the ranking based on magnitude [38] is done as follows: If Mag (A) < Mag (B) , then A ≺ B If Mag (A) > Mag (B) , then A ≻ B If Mag (A) = Mag (B) , then A ≈ B.
Solution of intuitionistic fuzzy multi-objective solid transportation problems
The mathematical formulation of the multi-objective solid transportation problem in an intuitionistic fuzzy environment is elaborated with appropriate notations in this section. An algorithm for solving the proposed mathematical model has also been described in detail.
Mathematical formulation of intuitionistic fuzzy multi-objective solid transportation problems (IFMOSTP)
Let i (i = 1, 2, 3 … m) items are to be transported to j (j = 1, 2, … . . n) destination through k (k = 1, 2 . . p) mode of transport,Ajk be the goods to be transported through kth means of transport to jthdestination,Bkiis the demand in ith product to be transported through kth means of transport,Eij is the ith product to be transported to the jthdestination, Fig. 2 is representation of constraints of proposed model.
where

Representation of constraints of proposed model.
The steps for finding an optimal solution to an intuitionistic fuzzy multi-objective solid transportation problem are as follows.
Representation of the IFMOSTP
Representation of the IFMOSTP
Representation of the reduced solid transportation problem
Make a closed loop starting with (–) sign at
Find the lower and upper bounds for each objective from the above matrix given by
Max λ
subject to
along with Equation (4)–(7)
Solving the above problem, the optimal compromise solution is obtained. LINGO software was applied to find the solution.
To illustrate the IFMOSTP model (3.1), we consider a transportation scenario in which three types of food products (p1, p2, p3), are to be transported to three different destinations using three different types of vehicle. The problem is to minimize the transportation cost of the vehicle, time taken, handling cost required during transportation. This factor depends on fuel rate, weather, vehicle efficiency, driver hours, etc, which is uncertain. The company is uncertain about the cost and time taken for delivering the product. Therefore, an approximate cost and time taken for transporting a product from each production unit to different places through type of vehicle is represented as PIFN.A
jk
is the goods to be transported through k
th
means of transport to j
th
destination.B
ik
is the demand in i
th
product to be transported through k
th
means of transport. E
ij
is the i
th
product to be transported to the j
th
destination.
The above data can be modeled as IFMOSTP as follows
where,
With
The unit transportation of penalties are given in Tables 5, 6, and 7. A11 = 4, A12 = 3, A13 = 3, A21 = 6, A22 = 8, A23 = 4, A31 = 5, A32 = 4, A33 = 6, B11 = 6, B12 = 5, B13 = 4, B21 = 5, B22 = 4, B23 = 4, B31 = 4, B32 = 6, B33 = 5, E11 = 5, E12 = 5, E13 = 5, E21 = 3, E22 = 6, E23 = 4, E31 = 2, E32 = 7, E33 = 6,
Penalties/unit transportation cost
Penalties/labor cost
Penalties/time taken to transport one unit item
Using Equation (2)
First consider single objective (ie) solve
Applying least cost method the feasible solution of the transportation problem is
B11 = 6,B12 = 5,B13 = 4,B21 = 5,B22 = 4,B23 = 4,B31 = 4,B32 = 6,B33 = 5.
In above allocated values of
Consider
Revised B
ik
values are
Applying least cost method the feasible solution of the transportation problem is
In the above check allocated values of
Now
Consider
Revised B
ik
values are
Now allocation of every occupied cell
Similarly solving for
Pay of matrix is formed as given in step 9 and is given below
Linear programming problem is formed as given in equation
Max λ
subject to
along with Equation (4)–(7)
Using Lingo optimizing software
We get λ = . 7655 x111 = 4, x112 = 1, x121 = 1.87, x122 = 3.12, x131 = .12, x132 = .89, x133 = 4, x212 = 1.41, x213 = 1.58, x221 = 4.1, x222 = .68, x223 = 1.2, x231 = .89, x232 = 1.8, x233 = 1.2, x312 = .58, x313 = 1.41, x322 = 4.2, x323 = 2.79, x331 = 4, x332 = 1.2, x333 = .79.68.
Optimal objective values of
In this section the drawbacks of the existing methods, comparison with an existing method, advantages and limitations of our proposed research work has been outlined. Which is given in Table 8.
Restrictions of existing transportation models along with the underlying features
Restrictions of existing transportation models along with the underlying features
As seen from the Table 9 proposed method minimizes all the objective function as compared with the algorithm provided in [39, 40–54]. Figure 3 is shows that comparison of proposed with existing methods optimal objective values.
Comparison of proposed method with existing method

Comparison between existing methods.
The MOSTP in intuitionistic fuzzy environment has been studied for the first time, which handle uncertainty in a better way. In this work PIFN are considered as parameter for MOSTP which is the generalized form of triangular intuitionistic fuzzy numbers (ie), in
The necessity of multi-objective transportation problems arises, when the objective is not only to minimize the cost of transportation but also to minimize transportation time, labor effort, etc. The proposed method yields an optimal solution for the given multi-objective transportation problem when the cost and time is uncertain. In this method, Lingo software is used to find the optimal solution. Future scope is may be extended in non-linear system by using intuitionistic fuzzy numbers. This method can help decision makers with the logistics related issues of real life problems in decision making process and provide an optimal solution in a simple and effective manner.
