Abstract
The occurrence of public health emergency will cause huge economic losses and casualties, which posed a huge threat to the economic and social development. In response to the emergency, a large amount of emergency relief supplies will be transported to the affected areas. Faced with this public health emergency of international concern, the concept of emergency logistics capacity and the evaluation model based on probabilistic linguistic term sets are proposed. In this paper, the emergency logistics capability evaluation is transformed into user demand evaluation, and the importance of each index of emergency logistics capability is determined by using Quality Function Deployment (QFD) and prospect theory. Under the probabilistic language information environment, a multi-attribute decision making method is established by using TODIM method. Finally, an example is given to verify the feasibility of the proposed method.
Keywords
Introduction
Emergency logistics is a special activity that aims to provide relief materials when natural disasters and public health emergencies occur and provides emergency support after emergencies, which can maximize time benefit and disaster loss [1]. In recent years, sudden natural disasters, public health events, social security events and other emergencies occur frequently in the world, and the research on emergency logistics has attracted more and more attention from scholars. In 1984, the logistics management method is applied to the dispatching process of disaster relief materials for the first time by Ken and Cook [2]; Aikens constructed nine models for selecting the optimal location in the warehouse construction process [3]; Carter believed that emergency logistics is the act of delivering emergency supplies to the point of demand in an accurate time according to the demand. After an emergency, the government should respond actively to ensure that emergency supplies reach the disaster area in the shortest time [4]; Suleyman proposed the early description of emergency logistics management, the construction of a comprehensive and effective emergency decision support system, to help rescue workers to carry out traffic control and emergency evacuation after the occurrence of emergency events, and make emergency relief materials quickly sent to the disaster area [5]. The research on emergency logistics in China started from SARS in 2003, and the related research on the evaluation of emergency logistics capability has been gradually deepened. He analyzed the causes of emergency logistics caused by natural disasters, decision-making mistakes, complex international environment, consumer rights protection and third parties [6]; Wang et al. defined the concept of emergency logistics, comprehensively expounded it, and pointed out the problems existing in the existing research [7]; Sun et al. defined the characteristics of emergency logistics, constructed the emergency logistics guarantee system and risk assessment model, and pointed out the future development trend of emergency logistics [8]. Emergency logistics requires not only timely release of emergency response by government departments, but also cooperation with all sectors of society. However, the academic research on emergency logistics capability is not thorough enough. This is also the direction of future research.
In 1965, Zadeh proposed the fuzzy set to describe relevant information [9], and then the concept of hesitating fuzzy set was proposed [10]. Rodriguez et al. proposed the hesitating fuzzy language term set combined with the language term set [12]. Pang et al. proposed the concept of probabilistic language term set (PLTSs) to express the preference of the decision maker and to deal with the information in the decision-making process effectively. The set of probabilistic language terms represents evaluation information through linguistic values and corresponding probabilities [13]; Then, Zhang et al. redefined some operations of the probabilistic language term set, so that the probability of the prediction term was reflected in the decision result and the decision result was guaranteed to be in the form of the probabilistic language term set [14]; Through equivalent transformation function, Guo et al. proposed the operation of probabilistic language term sets based on algebraic T-conorm and T-norm [15]; The distance measure is defined by the deviation degree of the normalized probabilistic language term set, Zhang proposed the distance measure of the normalized probabilistic language preference relation. Wang et al. proposed generalized distance and Hausdorff distance by introducing the concept of probabilistic language term set [16]; Then Liu and Li proposed Maclaurin symmetric average aggregation operator [17]; Pang et al. studied the extended TOPSIS method and information aggregation operator based on the probabilistic language decision making method [18]; According to the nature of language preference relation, Wu et al. proposed the probabilistic cosine similarity measure [19]; Lin et al proposed the distance measure between two probabilistic language term sets to reasonably measure the relationship between two corresponding language term sets, including Hamming distance, Euclidean distance, Hausdorff distance and mixed distance [20]. Mo proposed a new method to solve the problem of emergency decision-making named D-PLTS, which can be directly transferred to the form of the D number, no matter whether the information is complete or not [21]. At present, probabilistic language term sets have been successfully applied in many research fields.
In recent years, decision making methods based on language information have been widely studied and some achievements have been made. Some other methods have also been conducted to solve the problem of emergency decision making, such as D number theory. D number is a new tool for expressing and processing uncertain information. Its framework is based on evidence theory and is an effective extension of evidence theory, but it has more flexible and more relaxed application conditions than evidence theory. In d-number theory, decision experts are allowed to make reasonable evaluation of candidates without considering the integrity constraints of evaluation data, that is, it can clearly express unknown and uncertain information. Experts have flexibility in evaluation. After the expert evaluation information is collected, the expert evaluation information is regarded as D number, and then the information is integrated step by step with the relevant characteristics of D number, and finally the candidate’s final evaluation score is obtained, and then the ranking is carried out according to this. For example, Mo and Deng proposed a new methodology to deal with MADA problem based on D numbers [22]. The decision-making model is scientific and effective, and the process is intuitive, clear and time complexity is low.
Probabilistic language term sets not only enable participants or groups to use multiple language terms to express their judgments, but also reflect the preference of participants or groups to different language terms. It is more flexible and advantageous to use probabilistic language term sets to describe the opinions of decision-making groups. A probabilistic language decision matrix is used to express the opinions of the participant groups, which not only takes into account the different evaluations of the participants on the scheme, but also the different preferences of the participant groups on the evaluation information.
The structure of the paper is settled in the following. Section 2 presents some relevant basics. Section 3 proposes evaluation criteria for emergency logistics capacity. Section 4 establishes the multi-objective optimization by TODIM method using QFD and prospect theory. An application study is provided in Section 5 about the evaluation of emergency logistics capacity to verify the value of the presented framework in application. At last, the conclusions and possible directions for future research are analyzed in Section 6.
Preliminaries
Basic theory of PLTS
Firstly, this section introduces some basic definitions and operations for PLTSs.
S
i
< S
j
, when i < j; Neg (S
i
) = S
j
, when i = - j; max { S
i
, S
j
} = S
i
, when i ⩾ j; min { S
i
, S
j
} = S
j
, when i ⩾ j.
Where # L (p) is the number of all different linguistic terms in L (p).
If
Where
Let L1 (p) and L2 (p) be any two PLTS s, If If # L1 (p) ≠ # L2 (p), then add corresponding elements to the probabilistic language term sets with fewer elements.
Where
Given arbitrary L1 (p) and L2 (p) then following conclusions can be drawn: if E (L1 (p)) < E (L2 (p)), then L1 (p) < L2 (p); if E (L1 (p)) > E (L2 (p)), then L1 (p) > L2 (p); if E (L1 (p)) = E (L2 (p)), then if Δ (L1 (p)) < Δ (L2 (p)), then L1 (p) < L2 (p); if Δ (L1 (p)) > Δ (L2 (p)), then L1 (p) > L2 (p); if Δ (L1 (p)) = Δ (L2 (p)), then L1 (p) = L2 (p).
λL1 (p) ={ λL1 (k1) |k1 = 1, 2, . . . , # L1 (p) }
Where
The normalize Euclidean distance between L1 (p) and L2 (p) can be calculated by:
Tversky and Kahneman believed that managers had bounded rationality rather than complete rationality, and they showed irrational behavior in the face of risks. Based on this, they put forward the prospect theory. The value function is expressed as follows:
The decision maker measures gains and losses against reference points. Reference points are generally determined according to one’s own risk preference and psychological state. The reference point can be specified by the following methods: (1) the zero point, (2) the mean value, (3) the medium value, (4) the worst value and (5) the best value. We formally consider rational expectations as a reference point [25]. Prospect values under probabilistic linguistic environment are as follows:
TODIM method was first proposed by Gomes et al. It is an interactive multi-attribute decision making method based on prospect theory, which can adjust the parameters in the decision process according to the decision maker’s risk preference, and the result is more consistent with the decision maker’s preference, considering the decision maker’s psychological behavior. It is an effective method to solve multi-attribute decision making problem. Generally speaking, after the initial decision matrix is normalized by TODIM method, the overall advantage degree of each scheme is obtained by calculating the advantage degree between each scheme and other schemes. The optimal scheme is selected according to the overall advantages of each scheme. The greater the overall superiority, the better the scheme.
Set A ={ A1, A2, . . . , A
m
} represents the set of m alternatives, where A
i
represents the ith alternative. C ={ c1, c2, . . . c
n
} is the set of attributes, where C
j
represents the ith attribute. The corresponding attribute weight vector is denoted as w = (w1, w2, . . . , w
n
), and
Where w r = max{ w j |j ∈ N } w r = max { w1, w2, ⋯ , w n }.
Where, θ is the loss attenuation coefficient, indicating the sensitivity of decision makers to losses.
Emergency logistics capacity refers to the process of special logistics capacity for emergency activities in the event of an emergency, including the entire process of determining the purchase, sorting, transportation and delivery of materials to emergency relief points, starting from emergency needs analysis [26]. The evaluation of emergency logistics capability has strong flexibility and openness, and the evaluation system of emergency logistics capability is still in the development stage.
Emergency logistics capacity
The research on emergency logistics capability in China is still in the initial stage, and the main research focuses on the micro level, such as the definition, characteristics and index selection of emergency logistics capability. At present, there are few researches on emergency logistics capacity evaluation, and emergency logistics capacity evaluation will become an important research direction.
Li et al. constructed the Hilbert index space with support capacity as the center, put forward the comprehensive evaluation model of emergency logistics capability of railway military transportation support [27]. Yao et al. constructed a multi-level evaluation model of emergency logistics capability based on gray and fuzzy theory and applied gray scale theory and membership theory in fuzzy mathematics [28]. Sun et al. built an evaluation index system for emergency logistics using fuzzy analytic hierarchy process, including the input of emergency logistics system, operation management of emergency logistics and operation efficiency of emergency logistics [29]. Taking the emergency logistics capacity of the Beijing-Tianjin-Hebei region as the object, Ma et al. established the regional emergency logistics capacity model based on the fuzzy mattering element method, evaluated the emergency logistics capacity of the Beijing-Tianjin-Hebei region in recent years with this model. Based on this, the change chart of main index capability and the trend chart of comprehensive capability are obtained, and the conclusion of the research is summarized and verified in the end [30].
Based on the analysis and summary of related literatures on the evaluation of logistics capability at home and abroad, we divide the emergency logistics capability into 5 levels. They are defined as follows: initial stage (L1), individual response stage (L2), decentralized coordination stage (L3), coordinated efficiency stage (L4) and continuous improvement stage (L5). In order to better describe the characteristics of each level in emergency logistics, key links of emergency logistics including coordinated operational capability (C1) of each level, logistics operation supply (C2), information processing (C3), human resource management (C4) and influence degree (C5) are selected as the evaluation that constitute the evaluation index system. Different levels' characteristics for emergency logistics are given in Table 1.
Different levels’ characteristics for emergency logistics
Different levels’ characteristics for emergency logistics
Coordinated operational capability (C1): In the face of the emergency logistics demand, the government should establish the command organization and operation system in time, mainly to coordinate and dispatch emergency logistics in emergencies. The indicators are organizational mobilization ability, emergency logistics command and dispatch ability, command response time, organizational decision-making ability, etc.
Logistics operation supply (C2): It is the basic guarantee of emergency logistics activities. The evaluation of logistics operation supply capacity is mainly based on three specific indexes: emergency material support capacity, emergency material transportation and distribution capacity, and the rationality of emergency logistics center.
Information processing (C3): It refers to the role played by emergency logistics information in various processes in the whole emergency logistics activities. The information processing ability is evaluated from five specific indicators: the ability to monitor emergencies, the ability to predict emergencies, the ability to collect and analyze information, the ability to share information, and the ability to give information feedback.
Human resource management (C4): As the basic guarantee of emergency logistics, human resource evaluation is the core of emergency logistics capability test. The human resource support ability is evaluated from the indicators of personnel composition, expert support ability, personnel training and drills, personnel response processing ability and rescue team construction.
Influence degree (C5): It mainly evaluates the consequences brought by the emergency logistics activities after the emergency logistics, evaluates the overall satisfaction of the survey masses. The specific indicators mainly include the satisfaction rate of the masses and the number of complaints from the masses. After the emergency, the rescue workers to ensure the victims of the living supplies, psychological comfort. Emergency relief materials are related to the survival of the victims, should be distributed in accordance with the principle of “first urgent, then slow, focus", overall planning, reasonable arrangements, make full use of it.
Description
Assume that the emergency decision-making team consists of E
p
(1 ⩽ p ⩽ h) experts, the set composed of emergency areas is denoted as A ={ A1, A2, . . . , A
n
}. There are m indicators for evaluating emergency logistics capacity, and the index set is denoted as C ={ c1, c2, . . . c
m
}. The corresponding attribute weight vector is denoted as w = (w1, w2, . . . , w
n
), and
The proposed Importance calculation based on improved QFD
Quality Function Deployment (QFD) is a product design and development tool driven by user demand, which is widely used in the analysis of user demand to ensure product Quality and improve user satisfaction. Demand evaluation involves many qualitative and quantitative indicators [31]. Aimed at the uncertainty of demand evaluation environment and user preferences, using the user needs assessment in the mixed information characterization of QFD, considering the language more accord with experts in the expression of fuzzy situation habit, linguistic term set representation using probability relationship of demand and module in QFD, obtain high degree of differentiation of the needs of the expert important degree, determine the importance of requirements. In this paper, the emergency logistics capability evaluation is transformed into user demand evaluation, and the importance of each index of emergency logistics capability is determined by using QFD theory as the attribute weight. The demand analysis method at the user level is proposed to solve the impact of group consistency and balance on the demand analysis results, and the demand analysis method at the expert level is proposed to integrate the demand analysis into the group comprehensive decision-making process.
First, based on the attitude of experts, the optimization model is constructed. Prospect theory can well reflect the attitude of experts to user needs, and experts give the highest importance to the demand that is closest to the expectation, namely the demand with the largest prospect value. Build optimization goals to maximize the prospect value.
TODIM method was an effective method to solve multi-attribute decision making problems. Hu et al. proposed a new three-way decision model TODIM method, which adopts a new probability degree. Ji et al. proposed an item-based TODIM method for neutral information. Llamazares popularized the traditional TODIM method with a series of functions and proved some properties of the TODIM method. The key idea is to select the dominant value superior to other options. In general, after the normalization of the initial decision matrix, the traditional TODIM method obtains the overall advantage degree of each scheme by calculating the advantage degree between each scheme and other schemes. This method can only be used to solve the multi-attribute decision making problem where the evaluation attribute value is exact.
According to the criteria weights, calculate the relative weights of criterion c j :
Then calculate the dominance degree for alternative A i over A k in terms of criterion c j , where θ is the losses attenuation factor, d (b ij , b kj ) is the distance between b ij and b kj . The smaller the θ is, the better the loss aversion is.
The above formula indicates that the smaller θ is, the higher the risk of loss aversion of experts is.
Calculate the dominance degree for A i over A k in all criteria.
Then, calculate the overall dominance degree for A i :
In this Section, the TODIM method for PLTSs model for evaluation criteria for emergency logistics capacity will be built based on the prospect theory and QFD, as shown in Fig. 1.

The flowchart of the TODIM method for PLTSs model.
The epidemic of COVID-19 has seriously threatened human health and brought heavy burdens and severe challenges to the world economy and society. The global epidemic continues to spread, and the situation in some countries remains grim. Relevant researches on emergency logistics have become a major demand. In this COVID-19 pandemic, emergency logistics plays a key role in public health emergencies. Suppose that an occurrence of unexpected public health events caused huge economic losses and casualties. There were four representatives of the hardest-hit. Therefore, these four typical cities selected to be evaluated. They are A1, A2, A3 and A4. We assume that the five levels (L1, L2, L3, L4, L5) are the corresponding linguistic fuzzy terms s0, s1, s2, s3, s4. Suppose the assessment team has four experts (X1, X2, X3, X4) in the field of emergency management. Then, emergency logistics capacity of the four cities will be evaluated based on PLTSs.
Tables 2–5 can be translated into the following decision matrix B with PLTSs:
The assessment of Expert (X1) corresponding to different criteria
The assessment of Expert (X1) corresponding to different criteria
The assessment of Expert (X2) corresponding to different criteria
The assessment of Expert (X3) corresponding to different criteria
The assessment of Expert (X4) corresponding to different criteria
After normalization, matrix B can be transformed into normalized matrix
Dominance degrees for 4 cities
Scientific and reasonable evaluation of emergency logistics capacity is of great significance to the establishment and improvement of disaster relief material reserve system and emergency material guarantee system. This paper studies the concept of emergency logistics capability and the weight determination model based on QFD, which can better reflect the comprehensive effect of emergency logistics. On this basis, in order to fully reflect the expert preference and evaluation information, the evaluation model of the improved TODIM method is constructed by combining the probabilistic language term sets with the improved TODIM method. In terms of improving the information representation of QFD, considering the user’s preference for requirements and the vagueness and uncertainty of demand information and the difference degree of experts’ attitudes and users’ needs, it provides a more stable guarantee mechanism for the realization of users’ needs, and obtains the importance degree of demands at the expert level. The next step is to study the requirement importance determination method from the dual perspectives of user demand analysis and expert demand analysis.
Footnotes
Acknowledgments
This paper is supported by the National Social Science Foundation of China (NO: 20BTJ012), the Social Science Foundation of Hebei province of China (No. HB18GL008), Beijing Intelligent Logistics System Collaborative Innovation Center (BILSCIC-2019KF-15), and Philosophy and Social Science key cultivation project of Hebei University(2019HPY035).
