A two-stage optimization method for unmanned aerial vehicle inspection of an oil and gas pipeline network

Oil and gas pipeline networks are a key link in the coordinated development of oil and gas both upstream and downstream.To improve the reliability and safety of the oil and gas pipeline network, inspections are implemented to minimize the risk of leakage, spill and theft, as well as documenting actual incidents. In recent years, unmanned aerial vehicles have been recognized as a promising option for inspection due to their high efficiency. However, the integrated optimization of unmanned aerial vehicle inspection for oil and gas pipeline networks, including physical feasibility, the performance of mission, cooperation, real-time implementation and three-dimensional(3-D) space, is a strategic problem due to its large-scale,complexity as well as the need for efficiency. In this work, a novel mixed-integer nonlinear programming model is proposed that takes into account the constraints of the mission scenario and the safety performance of unmanned aerial vehicles. To minimize the total length of the inspection path, the model is solved by a two-stage solution method. Finally, a virtual pipeline network and a practical pipeline network are set as two examples to demonstrate the performance of the optimization schemes. Moreover, compared with the traditional genetic algorithm and simulated annealing algorithm, the self-adaptive genetic simulated annealing algorithm proposed in this paper provides strong stability.

Cycle number of neoadjuvant chemotherapy might influence survival of patients with T1-4N2-3M0 nasopharyngeal carcinoma

Objective： Stage N2-3 nasopharyngeal carcinoma（NPC） shows a high risk of distant metastasis, which will finally cause death. This study aimed to evaluate the impact of neoadjuvant chemotherapy（NACT） of various cycles before radical radiotherapy on distant metastasis and survival of patients with stage N2-3 diseases.Methods： In this study, a total of 1,164 consecutive patients with non-metastatic N2-3 NPC were recruited and prospectively observed. Then 231 patients who received NACT of 4 cycles（NACT=4 group） were matched 1：2：1 to 462 patients treated with NACT of 2 cycles（NACT=2 group） and 231 patients treated without NACT（NACT=0 group）, according to age, histological subtype, N stage and NACT regimen. Five candidate variables（sex, T stage, concurrent chemotherapy, intensity-modulated radiation therapy and cycle number of NACT） were analyzed for their association with patients＇ survival.Results： After matching, the overall survival（OS）, disease-free survival（DFS）, local-recurrence-free survival（RFS） and distant-metastasis-free survival（MFS） of the NACT=4 group（89.2%, 81.0%, 83.3% and 84.8%,respectively） were better than those of the NACT=2 group（83.3%, 72.5%, 81.2% and 77.9%, respectively） and the NACT=0 group（74.0%, 63.2%, 74.0% and 68.8%, respectively）. In multivariate analysis, the cycle number of NACT maintained statistical significance on the OS, DFS, RFS and MFS（all P〈0.05）.Conclusions： For N2-3 NPC, cycle number of NACT appeared to be an independent factor associated with an improvement of survival.

Layer-by-layer Assembled Multilayers of Graphene/Mono-(6-amino-6-deoxy)-β-cyclodextrin for Detection of Dopamine

Graphene/mono-(6-amino-6-deoxy)-β-cyclodextrin multilayer films composed of graphene sheet(GS)and mono-(6-amino-6-deoxy)-β-cyclodextrin(NH_(2)-β-CD)were fabricated easily by two steps.First,negatively charged graphene oxide(GO)and positively charged mono-(6-amino-6-deoxy)-β-cyclodextrin(NH_(2)-β-CD)were layer-by-layer(LBL)self-assembled on glassy carbon electrode(GCE)modified with a layer of poly(diallyldimethylammo-nium chloride)(PDDA).Then graphene/mono-(6-amino-6-deoxy)-β-cyclodextrin(GS/NH_(2)-β-CD)multilayer films were built up by electrochemical reduction of graphene oxide/mono-(6-amino-6-deoxy)-β-cyclodextrin(GO/NH_(2)-β-CD).Combining the high surface area of GS and the active recognition sites onβ-cyclodextrin(β-CD),the GS/NH_(2)-β-CD multilayer films show excellent electrochemical sensing performance for the detection of DA with an extraordinary broad linear range from 2.53 to 980.05μmol•L^(−1).This study offers a simple route to the controlla-ble formation of graphene-based electrochemical sensor for the detection of DA.