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RISS 인기검색어
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- 저자 : Wanlin Liu (검색결과 4 건)
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Bi-objective Optimization for Resource-constrained Robust Construction Project Scheduling
Wanlin Liu,Li Ge,Chunli Qu,Shun Yang 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1
Construction projects are often executed in complex environments, and various uncertain factors (e.g., bad weather, machine breakdown) prolong activity duration in practice, which may cause project completion delays or profit reduction. Moreover, previous studies often optimized net present value or robustness in project scheduling separately, they neglected the linkage between the value of obtaining NPV and the capacity of tackling uncertainties in a project schedule. To achieve optimal profit and enhance the stability of a project schedule simultaneously, this study proposes a bi-objective optimization for resource-constrained robust construction project scheduling problem (RCRCPSP), which aims at optimizing NPV and robustness, and builds a bi-objective optimization model for the RCRCPSP based on five typical cash flow models. Then an -constraints procedure embedded with a genetic algorithm is proposed to solve the model. The -constraints procedure performs better than the multi-objective genetic algorithm proposed by the previous study through case study. Furthermore, the findings demonstrate that a trade-off relationship exists between NPV and robustness, and cash flow models have little impact on robustness, while the relaxed deadline can improve a project schedule with high robustness. The fruits of this study can help contractors balance the NPV and the robustness in an indeterministic environment.
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Reactive Procedure for Robust Project Scheduling under the Activity Disruptions
Lei Li,Wanlin Liu,Yumeng Chen,Shun Yang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.9
The baseline schedule may become infeasible when disruptions happen during the execution of project. This will lead to project delays and financial losses. In this paper, we developed a robust reactive optimization model. Our objective is to maximize the robustness of reactive schedule. Moreover, a robust reactive procedure is proposed for baseline schedule under a series of disruptions caused by activity duration. To test the proposed approach, sets of J60 and J90 instances from the Project Scheduling Library (PSPLIB) were used. Meanwhile, we tested the reactive project scheduling with the aim of minimizing makespan and compared the maximal robustness reactive schedule and the minimal makespan reactive schedule. We developed a reactive procedure involving genetic algorithm for reactive scheduling due to its non-deterministic polynomial hard (NP-hard). The results indicated that robust reactive scheduling has the advantage in maintaining the schedule’s ability of tolerating variabilities and reducing the impact of activity disruptions on the makespan. The research results can help project managers develop a robust schedule which can tolerate variabilities in a random environment.
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Xiangyu Li,Jianwei Zhang,Juan Liu,Wanlin Cao 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.10
The bond behavior of spiral ribbed ultra-high strength (SRUHS) steel rebar embedded in plain high strength concrete (HSC) and steel fiber reinforced high strength concrete (SFRHSC) is experimentally studied using pull-out tests. The influencing factors of concrete type, embedded length, cover thickness and stirrup ratio are considered and the bond failure characteristics as well as the whole process of stress-slip behavior are analyzed. The research shows good anchorage ductility between SRUHS steel rebar and HSC. Since SRUHS steel rebars have continuous spiral bite teeth with concrete, the concrete in the rib dales is not easily sheared off, thereby leading to a reliable bond strength. Compared to specimens without steel fibers, steel fiber reinforcement can increase the ultimate bond strength, bond stiffness and residual strength. Meanwhile, it will also reduce the influence of cover thickness, stirrup ratio on the specimens with steel fibers. Finally, a prediction calculation for ultimate bond stress and an analytical model for bond stress-slip relation are proposed, which match well with test results.
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Li Xiaojuan,Dong Guangping,Fang Jianmin,Liu Hongjian,Guo Wanlin,Yin Huayang 한국곤충학회 2020 Entomological Research Vol.50 No.7
Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) is an effective ectoparasitoid of pine sawyer beetle Monochamus alternatus Hope (Coleoptera: Cerambycidae) which is the major median insect for transmission of pine wood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle (Aphelenchida: Parasitaphelenchidae). A sensitive and acute olfactory system is extremely essential for newly hatched larva of D. helophoroides to forage for a host. Therefore, we established the transcriptome of newly hatched D. helophoroides larvae and characterized the expression profiles of olfactory genes. We identified 20 transcripts encoding putative odorant binding proteins (OBPs), 11 putative chemosensory proteins (CSPs), 9 putative odorant receptors (ORs), 11 putative ionotropic receptors (IRs), 7 putative gustatory receptors (GRs) and 4 putative sensory neuron membrane proteins (SNMPs) olfactory genes from the transcriptome of newly hatched D. helophoroides larvae. According to the phylogenetic analysis, 3 OBPs (DhelOBP6, DhelOBP14 and DhelOBP19), 1 CSP (DhelCSP11), 1 OR (DhelOrco1), 3 IRs (DhelIR3, DhelIR6 and DhelIR8), 3 GRs (DhelGR2, DhelGR4 and DhelGR5) and 2 SNMPs (DhelSNMP1 and DhelSNMP3) had high similarities with reported Coleopteran species. The highest expressed olfactory gene was DhelCSP3, followed by DhelOBP8 and DhelCSP2. The expression levels of the majority of OR, IR, GR and SNMP genes were low. These results indicate that CSPs and OBPs may play important roles in the olfactory recognition process in newly hatched D. helophoroides larvae. The findings from the present study are helpful in unraveling the profound mystery between D. helophoroides and M. alternatus, as well as improving the parasitism efficiency of D. helophoroides larvae.
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