Automatic Truss Design with Reinforcement Learning

Truss layout design, namely finding a lightweight truss layout satisfying all the physical constraints, is a fundamental problem in the building industry. Generating the optimal layout is a challenging combinatorial optimization problem, which can be extremely expensive to solve by exhaustive search. Directly applying end-to-end reinforcement learning (RL) methods to truss layout design is infeasible either, since only a tiny portion of the entire layout space is valid under the physical constraints, leading to particularly sparse rewards for RL training. In this paper, we develop AutoTruss, a two-stage framework to efficiently generate both lightweight and valid truss layouts. AutoTruss first adopts Monte Carlo tree search to discover a diverse collection of valid layouts. Then RL is applied to iteratively refine the valid solutions. We conduct experiments and ablation studies in popular truss layout design test cases in both 2D and 3D settings. AutoTruss outperforms the best-reported layouts by 25.1% in the most challenging 3D test cases, resulting in the first effective deep-RL-based approach in the truss layout design literature.Comment: IJCAI2023. The codes are available at https://github.com/StigLidu/AutoTrus

Methylprednisolone as Adjunct to Endovascular Thrombectomy for Large-Vessel Occlusion Stroke

Importance It is uncertain whether intravenous methylprednisolone improves outcomes for patients with acute ischemic stroke due to large-vessel occlusion (LVO) undergoing endovascular thrombectomy. Objective To assess the efficacy and adverse events of adjunctive intravenous low-dose methylprednisolone to endovascular thrombectomy for acute ischemic stroke secondary to LVO. Design, Setting, and Participants This investigator-initiated, randomized, double-blind, placebo-controlled trial was implemented at 82 hospitals in China, enrolling 1680 patients with stroke and proximal intracranial LVO presenting within 24 hours of time last known to be well. Recruitment took place between February 9, 2022, and June 30, 2023, with a final follow-up on September 30, 2023.InterventionsEligible patients were randomly assigned to intravenous methylprednisolone (n = 839) at 2 mg/kg/d or placebo (n = 841) for 3 days adjunctive to endovascular thrombectomy. Main Outcomes and Measures The primary efficacy outcome was disability level at 90 days as measured by the overall distribution of the modified Rankin Scale scores (range, 0 [no symptoms] to 6 [death]). The primary safety outcomes included mortality at 90 days and the incidence of symptomatic intracranial hemorrhage within 48 hours. Results Among 1680 patients randomized (median age, 69 years; 727 female [43.3%]), 1673 (99.6%) completed the trial. The median 90-day modified Rankin Scale score was 3 (IQR, 1-5) in the methylprednisolone group vs 3 (IQR, 1-6) in the placebo group (adjusted generalized odds ratio for a lower level of disability, 1.10 [95% CI, 0.96-1.25]; P = .17). In the methylprednisolone group, there was a lower mortality rate (23.2% vs 28.5%; adjusted risk ratio, 0.84 [95% CI, 0.71-0.98]; P = .03) and a lower rate of symptomatic intracranial hemorrhage (8.6% vs 11.7%; adjusted risk ratio, 0.74 [95% CI, 0.55-0.99]; P = .04) compared with placebo. Conclusions and Relevance Among patients with acute ischemic stroke due to LVO undergoing endovascular thrombectomy, adjunctive methylprednisolone added to endovascular thrombectomy did not significantly improve the degree of overall disability.Trial RegistrationChiCTR.org.cn Identifier: ChiCTR210005172

Effect of Nitrile Group Functionalized Organosilicon as Electrolyte Additive on Low. temperature Performance of LiFePO4 Battery

A nitrile group functionalized organosilicon compound, 3-(diethoxy-methyl-silanyl)-propionitrile (DESCN) was synthesized and its chemical structure and electrochemical window were characterized. The effects of DESCN on the low-temperature performance of LiFePO4 cell were investigated by charge-discharge cycling test, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy(EIS) and so on. It is revealed that adding 2% DESCN could improve the low-temperature performance of LiFePO4 cell. At - 20 degrees C, the cell exhibits a high discharge capacity of 73 mA.h/g and are stable after 50 cycles. DESCN involved in the formation of stable solid electrolyte interface(SEI) film to inhibit electrolyte decomposition and decrease the battery resistance, which facilitate Li+ diffusion and electron transportation at electrode/electrolyte interface at low-temperature

A Novel Aminoalkylsilane Compound with Oligo(ethylene oxide) Units as Effective Additive for Improving Cyclability of Lithium-ion Batteries

A new aminoalkylsilane compound, ((2-(2-(N,N-dimethylamino)ethoxy)ethoxy) methyl)trimethylsilane (TMSC1N2) based on the oligo(ethylene oxide) chain end-capped with organosilicon functional group and alkylamine group on each end, was introduced as an electrolyte additive for lithium-ion batteries. Electrochemical performances of different volume ratios of TMSC1N2 in the baseline electrolyte were conducted through cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge tests of lithium-ion batteries. With adding 5 vol.% TMSC1N2 to the baseline electrolyte (1 mol/L LiPF6 in ethylene carbonate and diethyl carbonate (EC:DEC = 1: 1, in volume)), the capacity retention of LiFePO4/Li cells could be significantly improved from 74.7% to 90.8% after 130 cycles. Furthermore, TMSC1N2 showed good compatibility with graphite electrode and would not deteriorate the electrochemical performance of graphite/Li anode cells. These data suggested that TMSC1N2 could be utilized as an effective additive for lithium-ion batteries

A Novel Aminoalkylsilane Compound with Oligo(ethylene oxide) Units as Effective Additive for Improving Cyclability of Lithium-ion Batteries

A new aminoalkylsilane compound, ((2-(2-(N,N-dimethylamino)ethoxy)ethoxy) methyl)trimethylsilane (TMSC1N2) based on the oligo(ethylene oxide) chain end-capped with organosilicon functional group and alkylamine group on each end, was introduced as an electrolyte additive for lithium-ion batteries. Electrochemical performances of different volume ratios of TMSC1N2 in the baseline electrolyte were conducted through cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge tests of lithium-ion batteries. With adding 5 vol.% TMSC1N2 to the baseline electrolyte (1 mol/L LiPF_6 in ethylene carbonate and diethyl carbonate (EC:DEC = 1:1, in volume)), the capacity retention of LiFePO_4/Li cells could be significantly improved from 74.7% to 90.8% after 130 cycles. Furthermore, TMSC1N2 showed good compatibility with graphite electrode and would not deteriorate the electrochemical performance of graphite/Li anode cells. These data suggested that TMSC1N2 could be utilized as an effective additive for lithium-ion batteries

Synthesis of aminoalkylsilanes with oligo(ethylene oxide) unit as multifunctional electrolyte additives for lithium-ion batteries

Aminoalkylsilanes with oligo(ethylene oxide) units were designed and synthesized as multifunctional electrolyte additives for lithium-ion batteries. The chemical structures were fully characterized by nuclear magnetic resonance (NMR) spectroscopy and their thermal properties, viscosities, electrochemical windows, and ionic conductivities were systematically measured. With adding one of these compounds (1 vol. %, DSC3N1) in the baseline electrolyte 1.0 M LiPF6 in EC: DEC (1:1, in volume), Li/LiCoO2 half cell tests showed an improved cyclability after 100 cycles and improved rate capability at 5C rate condition. Electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopic (EDS) analysis confirmed the acid scavenging function and film forming capability of DSC3N1. These results demonstrated that the multifunctional organosilicon compounds have considerable potential as additives for use in lithium-ion batteries

Novel choline-based ionic liquids as safe electrolytes for high-voltage lithium-ion batteries

Three choline-based ionic liquids functionalized with trimethylsilyl, allyl, and cynoethyl groups are synthesized in an inexpensive route as safe electrolytes for high-voltage lithium-ion batteries. The thermal stabilities, viscosities, conductivities, and electrochemical windows of these ILs are reported. Hybrid electrolytes were formulated by doping with 0.6 M LiPF6/0.4 M lithium oxalydifluoroborate (LiODFB) as salts and dimethyl carbonate (DMC) as co-solvent. By using 0.6 M LiPF6/0.4 M LiODFB trimethylsilylated choline-based IL (SN1IL-TFSI)/DMC as electrolyte, LiCoO2/graphite full cell showed excellent cycling performance with a capacity of 152 mAh g(-1) and 99% capacity retention over 90 cycles at a cut-off voltage of 4.4 V. The propagation rate of SN1IL-TFSI)/DMC electrolyte is only one quarter of the commercial electrolyte (1 M LiPF6 EC/DEC/DMC, v/v/v = 1/1/1), suggesting a better safety feature. (C) 2016 Elsevier B.V. All rights reserved

anovelorganosiliconbasedionicplasticcrystalassolidstateelectrolyteforlithiumionbatteries

A novel organosilicon-based ionic plastic crystal, N,N,N,-diethylmethyl-N-(trimethylsilyl)methylammonium bistrifluoromethane sulfonimide (DTMATFSI) was designed and synthesized as solid-state electrolyte for lithium-ion batteries. The chemical structure and the physical and electrochemical properties were characterized in detail. The ionic conductivity of DTMATFSI was improved significantly by doping with lithium oxalyldifluoroborate (LiODFB) and propylene carbonate (PC). An optimized plastic crystal composite (DTMATFSI:LiODFB:PC=8:1:1 in molar ratio) as a solid-state electrolyte exhibited a decent cycling stability in LiFePO_4/Li half-cell, with a specific discharge capacity of 144 mA·h/g and capacity retention of 94% after 50 cycles at C/20

Synergistic film-forming effect of oligo(ethylene oxide)-functionalized trimethoxysilane and propylene carbonate electrolytes on graphite anode

Oligo(ethylene oxide)-functionalized trialkoxysilanes can be used as novel electrolytes for high-voltage cathode, such as LiCoO2 (4.35 V) and Li1.2Ni0.2Mn0.6O2 (4.6 V); however, they are not well compatible with graphite anode. In this study, a synergistic solid electrolyte interphase (SEI) film-forming effect between [3-[2-(2-methoxyethoxy)ethoxy]propyl]-trimethoxysilane (TMSM2) and propylene carbonate (PC) on graphite electrode was investigated. Excellent SEI film-forming capability and cycling performance was observed in graphite/Li cells using the electrolyte of 1 M LiPF6 in the binary solvent of TMSM2 and PC, with the PC content in the range of 10-30 vol.%. Meanwhile, the graphite/Li cells delivered higher specific capacity and better capacity retention in the electrolyte of 1 M LiPF6 in TMSM2 and PC (TMSM2:PC = 9:1, by vol.), compared with those in the electrolyte of 1 M LiPF6 in TMSM2 and EC (TMSM2:EC = 9:1, by vol.). The synergistic SEI film-forming properties of TMSM2 and PC on the surface of graphite anode was characterized by electrolyte solution structure analysis through Raman spectroscopy and surface analysis detected by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR) analysis