Resource-constrained Time-cost-quality-energy- environment Tradeoff in Project Scheduling by Considering Blockchain Technology: A Case Study of Healthcare Project


 Blockchain Technology (BCT) is expanding day by day and is used in all pillars of life and projects. In this research, we survey applicable of BCT in project management for the first time. We presented a Resource-Constrained Time-Cost-Quality-Energy-Environment tradeoff problem in project scheduling by considering BCT (RCTCQEEBCT). We utilize hybrid robust stochastic programming, worst case and Conditional Value at Risk (CVaR) to cope with uncertainty and risks. This type of robustification and risk-averse is presented in this research. A real case study is presented in a healthcare project. We utilize GAMS-CPLEX to solve the model. Finally, we analyze finish time, conservative coefficient, the confidence level of CVaR and the number of scenarios. The most important research result is that applying BCT decreases cost, energy, and pollution and increases quality. Moreover, the total gap between RCTCQEEBCT and without BCT is approximately 2.6%. When compacting finish time happens or if the conservative coefficient increases to 100%, costs, energy, and pollution environment increase, but quality decreases. If the confidence level of CVaR increase, the cost, energy and environment function functions grow up and quality is approximately not changed.


Introduction
Nowadays, Blockchain Technology (BCT) is one of the novel technology can change the world 32 and move to decentralize and remove inefficiencies of centralized systems. Recently, Using BCT 33 in Project Management Offices (PMOs) is suggested by researchers (Hewavitharana,34 Nanayakkara, & Perera, 2019). Applying this technology makes to improve and to do activities 35 well and on time. For example, defining suppliers' delay when they act actions with disruption by 36 embedding BCT is concise. Moreover, the smart contract can help pay the vendor and 37 subcontractor automatically and remove the delay in payment (Akhavan,Ravanshadnia,& 38 Shahrayini). This issue decreases cost, improves the quality of activity, energy consumption, and 39 reduces executing time and project pollution (Kim, Lee, & Kim, 2020). 40 Of course, there is not much research on the applicability of BCT in project management. We need 41 to show how to improve scheduling, quality, energy, and pollution by considering BCT in the Time-cost-quality-energy-environment tradeoff (TCQEE) is one of the subjects that shows how 48 BCT helps schedule well and improve sustainability and resource constraints. In the future, we 49 have to go to novel technology to amplify resiliency in a complex situation like COVID-19 and 50 natural disasters and disruptions in project management. The leading organization in the project 51 industry worldwide tries to minimize the time of projects and do more tasks. 52 Eventually, the innovation of this research and the main objective is as follows: 53 1. Applying BCT in project scheduling in TCQEE problem, 54 2. Considering risk and robustness in TCQEE model, 55 3. Sustainability, resiliency, and agility improvement in project scheduling by 56 RCTCQEEBCT model. 57 The paper is organized as follows. In Section 2, we survey related work on time-cost tradeoff. In 58 Section 3, the novel TCQEE by considering BCT is stated. In Section 4, the results of research and 59 sensitivity analysis are presented. In Section 5, the managerial insights and practical implications 60 is discussed. In Section 6, the conclusion is summarized.  76 Wood (2017) surveyed a time-cost-quality (TCQ) tradeoff for Gas and oil project. They applied 77 stochastic and fuzzy multi-objective for optimization. They solve the model by using a memetic 78 multi-objective algorithm. Kosztyán  at the beginning of the project (Bowman, 1994). 158 In the following, the mathematical model of the time-cost-quality-energy-environment tradeoff is 159 introduced. In Figure 2, we show that duration ( is

169
Sustainable objectives: subject to: Resilience constraints (BCT technology): , Agile, predecessor, successor, and resource constraints: , is js Decision variables: The objective function (1) 192 Linearizing product binary with non-negative variable: 193 We can change and linearize a binary and a non-negative variable that is produced: 194 Suppose z Ax  , if A be a non-negative and positive variable and x be binary variable. Therefore 195 we can replace these constraints to the model (Glover, 1975): , zA  (1 ) . z A x M      207 We used linearization by the operational research method. Solving the model by MIP is more 208 straightforward than MINLP in the solver in equations (26) to (36), and these methods decrease 209 time solution and the complexity of the model. 210 We can write it as follows:  (1 ) 0.5 ( ( )), CVaR

221
This section surveys a healthcare project that establishes a hospital with 500 beds (c.f. Figure 3). 222 Data and information received from managers of healthcare projects. In this complex situation of 223 COVID-19, we should run these hospitals as soon as possible in Iran. Patients need beds for 224 remedy. Therefore, we should establish a hospital with minimum cost, energy, and environment, 225 and maximum quality to provide patients with good quality. We show network and predecessor and successor of activities in Figure 4. The number of indices, 228 constraints, variables and parameters is defined for the case study in Table 2, Table 3.

Parameters
Value Unit   We applied a computer with this configuration: CPU 3.2 GHz, Processor Core i3-3210, 6.00 GB 235 RAM, 64-bit operating system. Finally, we solve the mathematical models by GAMS-CPLEX 236 solver. 237 The results show that applying BCT decreases cost, energy, and pollution and increases quality, 238 as shown in Table 4, Table 5 and Figure 5. The total Gap between P1-RCTCQEEBCT and without 239 BCT is approximately 2.6%. Therefore, we suggest using and activating BCT to improve costs, 240 quality, energy, and environment. This subject increases resiliency and sustainability in project 241 management and increases responsibility and agility between pillars of projects. 242

247
As can be seen, we surveyed and changed finish time ( T ). When compacting finish time happens, 248 costs, energy, and pollution environment increase, but quality decreases. It is entirely natural 249 because by decreasing time, pushing project is occurred, therefore costs, energy, pollution 250 environment increase, and finally we see decreasing quality (cf. Figure 6 and Table 6).
251 Figure 6. Variation on the Finish time. In this section, we do a variation on the conservative coefficient for decision-makers with risk-

261
In this section, we do a variation on the confidence level of CVaR for decision-makers with risk-262 averse behavior until surveying the performance of mathematical model. If the confidence level of 263 CVaR, change between 1% to 5%, the cost, energy and environment function functions grow up 264 and quality is approximately not changed (cf. Table 8, Figure 8). 265

267
In this section, we do a variation on the number of scenarios for surveying the performance of 268 mathematical model. If the number of scenarios, change between 3 to 9, the cost function decrease. 269 Also, overall, quality and energy are declining and environment function is increasing (cf . Table   270 9, Figure 9). 271 Figure 9. Variation on the number of scenarios.    291 This research focuses on the applicability of BCT in project scheduling. We proposed a time-cost-292 quality-energy-environment tradeoff by considering BCT. Applying BCT make to decreases cost, 293 energy, environmental (pollution) and increase quality. By using BCT, we can improve all 294 objectives by 2.6%. We suggest that all project managers embed novel technology like BCT to 295 their projects to improve the performance of activities. 296 In this research, we apply BCT as resiliency tools and consider resource constraints, relation of 297 network pillar as agility tools. Moreover, utilizing BCT make to increasing resiliency, agility and 298 sustainability in the project management area. Resiliency and flexibility in facing costs by doing 299 activities short and increasing transparency in transaction and exchange with vendors and suppliers 300 with agility. BCT can help project management on digital record storage, digital asset exchange, 301 acceptable conduct assurance, reputation building, and intelligent contract execution. BCT 302 changes the environment of projects from passive to active and can implement strategic projects 303 in organizations. 304 Therefore, as managers of projects, we should move and apply novel technology in projects until 305 resiliency, sustainability, and agility increase day by day. Apply and embed BCT in project 306 management to increase resiliency and sustainability in project management and increase 307 responsibility and agility between pillars of the project. 308

309
The BCT is growing up day by day, and entrance in the life of humans and projects. Researchers 310 and investors need to use it in their work. Therefore, we proposed to utilize BCT in project 311 management to witness the efficiency as much as possible. In this research, we suggested using 312 BCT and showed a mathematical model. We employed BCT as resiliency tools and considered 313 resource constraints, relation of network pillar as agility constraints. 314 We used a hybrid robust optimization with considering a risk-averse approach for modeling 315 TCQEE tradeoff. We applied weighted expected value, minimax and CVaR for all objective 316 functions for robustness and risk-averse against disruption with the worst condition. 317 The findings of this research are as follows: 318 1. The results show that applying BCT decreases cost, energy, and pollution and increases 319 quality, as shown in Table 4, Table 5 and Figure 5. Total Gap P1-RCTCQEEBCT and 320 without BCT is approximately 2.6%. Therefore, we suggest using and activating BCT to 321 improve costs, quality, energy and environment.