Application Strategy of Digital Comprehensive Management and Maintenance System for Bridges

Effective application of digital integrated management and maintenance systems is essential for successful operation and maintenance management of bridge projects.This article analyzes the application strategy of such systems.It provides an overview of comprehensive digital management and maintenance of bridges,an analysis of the basic components of the integrated management and maintenance system,and its application strategies.This study aims to offer guidance for the application of the system and to improve the quality of modern bridge engineering management and maintenance work.

Heterostructured Mn_(3)O_(4)-MnS Multi-Shelled Hollow Spheres for Enhanced Polysulfide Regulation in Lithium-Sulfur Batteries

Constructing heterojunctions and hollow multi-shelled structures can render materials with fascinating physicochemical properties,and have been regarded as two promising strategies to overcome the severe shuttling and sluggish kinetics of polysulfide in lithium-sulfur(Li-S)batteries.However,a single strategy can only take limited effect.Modulating catalytic hosts with synergistic effects are urgently desired.Herein,Mn_(3)O_(4)-MnS heterogeneous multi-shelled hollow spheres are meticulously designed by controlled sulfuration of Mn2O3 hollow spheres,and then applied as advanced encapsulation hosts for Li-S batteries.Benefiting from the separated spatial confinement by hollow multi-shelled structure,ample exposed active sites and built-in electric field by heterogeneous interface,and synergistic effects between Mn_(3)O_(4)(strong adsorption)and MnS(fast conversion)components,the assembled battery achieves prominent rate capability and decent cyclability(0.016%decay per cycle at 2 C,1000 cycles).More crucially,satisfactory areal capacity reaches up to 7.1 mAh cm^(-2)even with high sulfur loading(8.0 mg cm^(-2))and lean electrolyte(E/S=4.0 pL mg^(-1))conditions.This work will provide inspiration for the rational design of hollow multi-shelled heterostructure for various electrocatalysis applications.

Causal effects of circulating vitamin levels on the risk of heart failure:a Mendelian randomization study

BACKGROUND Observational studies suggest inverse associations between serum vitamin levels and the risk of heart failure(HF). However, the causal effects of vitamins on HF have not been fully elucidated. Here, we conducted a Mendelian randomization(MR) study to investigate the causal associations between genetically determined vitamin levels and HF.METHODS Genetic instrumental variables for circulating vitamin levels, including vitamins A, B, C, D, and E, which were assessed as either absolute or metabolite levels were obtained from public genome-wide association studies. Summary statistics for single-nucleotide-polymorphisms and HF associations were retrieved from the HERMES Consortium(47,309 cases and 930,014controls) and FinnGen Study(30,098 cases and 229,612 controls). Two-sample MR analyses were implemented to assess the causality between vitamin levels and HF per outcome database, and the results were subsequently combined by meta-analysis.RESULTS Our MR study did not find significant associations between genetically determined circulating vitamin levels and HF risk. For absolute vitamin levels, the odds ratio for HF ranged from 0.97(95% confidence interval [CI]: 0.85–1.09, P = 0.41) for vitamin C to 1.05(95% CI: 0.61–1.82, P = 0.85) for vitamin A. For vitamin metabolites, the odds ratio ranged between 0.94(95% CI:0.75–1.19, P = 0.62) for α-tocopherol and 1.11(95% CI: 0.98–1.26, P = 0.09) for γ-tocopherol.CONCLUSION Evidence from our study does not support the causal effects of circulating vitamin levels on HF. Therefore,there may be no direct beneficial effects of vitamin intake on the prevention of primary HF.

Laboratory demonstration of geopotential measurement using transportable optical clocks

We report an experimental demonstration of geopotential difference measurement using a pair of transportable ^(40)Ca^(+) optical clocks(TOC-729-1 and TOC-729-3)in the laboratory,each of them has an uncertainty of 1.3×10^(−17) and an instability of 4.8×10^(−15)/√τ.Referenced to a stationary clock of TOC-729-1,the geopotential difference measurements are realized by moving TOC-729-3 to three different locations and the relevant altitude differences are measured with uncertainties at the level of 20 cm.After correcting the systematic shifts(including gravitational red shift),the two-clock frequency difference is measured to be–0.7(2.2)×10^(−17),considering both the statistic(1.0×10^(−17))and the systematic(1.9×10^(−17))uncertainties.The frequency difference between these two clocks is within their respective uncertainties,verifying the reliability of transportable ^(40)Ca^(+) optical clocks at the low level of 10^(−17).

Sympathetic electromagnetically induced transparency ground state cooling of a~(40)Ca^(+)–~(27)Al^(+)pair in an~(27)Al^(+)clock

We report on electromagnetically induced transparency cooling of ^(40)Ca^(+)to sympathetically cool the threedimensional secular modes of motion in a ^(40)Ca^(+)–^(27)Al^(+)two-ion pair near the ground state.We observe simultaneous ground state cooling across all radial modes and axial modes of a ^(40)Ca^(+)–^(27)Al^(+)ion pair,occupying a broader cooling range in frequency space over 3 MHz.The cooling time is observed to be less than 1 ms.The mean phonon number and heating rates of all motional modes are measured.This study is not only an important step for reducing the secular motion time-dilation shift uncertainty and uptime ratio of ^(27)Al^(+)optical clock,but also essential for high-fidelity quantum simulations and quantum information processors using trapped ions.

青海省黑颈鹤的研究、生态分布与保护现状

青海省是黑颈鹤(Grus nigricollis)模式标本的采集地,该地区有关黑颈鹤的研究,始于20世纪80年代。青海省也是最早人工繁殖黑颈鹤成功的地方。由于其独特的高原地貌,青海省成为黑颈鹤较为优越的繁殖栖息地。除东部的农业区外,黑颈鹤繁殖栖息地几乎遍布全省。同时,青海省建立了庞大的湿地自然保护区,面积约20万km2,占全省国土面积的2/7。然而,目前已知的黑颈鹤繁殖对还不到200对,大量的繁殖对分布信息还需要继续进行调查。人类在黑颈鹤繁殖栖息地的活动加剧,对黑颈鹤保护研究支持力度的欠缺以及在湿地调查和监测中,相关人员缺乏专业培训等现象,是日后需要重视和解决的首要问题。

雅鲁藏布江中上游河谷越冬黑颈鹤的数量变化

2007—2014年隆冬季节,对雅鲁藏布江中上游河谷越冬黑颈鹤(Grus nigricollis)的种群数量进行了8次调查统计。研究结果显示:(1)雅鲁藏布江中上游河谷越冬黑颈鹤的种群数量平均为(1541±227)只,种群数量表现出一定的波动性。2007年到2010年,越冬黑颈鹤的种群数量有所减少;2010年到2013年,种群数量增加;2014年种群数量又有所下降。(2)越冬黑颈鹤种群数量与河谷南侧黑颈鹤种群数量成显著正相关(P<0.01,r=0.928);河谷北侧黑颈鹤种群数量相对南侧较少,但稳定程度高于南侧。(3)越冬地的黑颈鹤以集群越冬为主,独立家庭和单独个体越冬的十分罕见。(4)8次记录的最大集群数为375只。(5)通过对2014年黑颈鹤种群栖息地利用情况的分析,发现麦茬地利用率占到所有栖息地类型的79.14%,翻耕地占3.73%,冬小麦地占0.76%,其他类型占16.37%。

酸性离子液体催化合成N-氰乙基-N-羟乙基苯胺

N-氰乙基-N-羟乙基苯胺是一种具有广泛用途的染料中间体,针对传统合成方法中的缺陷,以1-丁基-3-甲基咪唑硫酸氢盐([BMIM]HSO 4)为催化剂,丙烯腈和N-羟乙基苯胺为原料,建立了N-氰乙基-N-羟乙基苯胺的绿色合成新工艺。系统考察了离子液体种类、离子液体用量、底物比例等因素的影响规律,结果表明,[BMIM]HSO 4用量为0.8 mmol,n(N-羟乙基苯胺)∶[KG-*3/5]n(丙烯腈)=1∶[KG-*3/5]1.2,反应温度为90℃,反应时间为12 h时,N-氰乙基-N-羟乙基苯胺产率最高(89%),离子液体循环使用5次后,催化活性基本保持不变。

Reliable and Efficient Long-Term Social Media Monitoring

Social media data is now widely used by many academic researchers. However, long-term social media data collection projects, which most typically involve collecting data from public-use APIs, often encounter issues when relying on local area network servers (LANs) to collect high-volume streaming social media data over long periods of time. In this paper, we present a cloud-based data collection, pre-processing, and archiving infrastructure, and argue that this system mitigates or resolves the problems most typically encountered when running social media data collection projects on LANs at minimal cloud-computing costs. We show how this approach works in different cloud computing architectures, and how to adapt the method to collect streaming data from other social media platforms. The contribution of our research lies in the development of methodologies that researchers can use to monitor and analyze phenomena including how public opinion and public discourse change in response to events, monitoring the evolution and change of misinformation campaigns, and studying how organizations and entities change how they present and frame information online.

The Short-Term Effect of Online Violent Stimuli on Aggression

The significance of this study was to find whether violent stimuli exposure could escalate the following levels of aggression in order to better cultivate aggression education among contemporary undergraduates in China. This study mainly tested the effects of violent stimuli on aggression by employing modified Stroop task. A total of 188 undergraduates participated in this study. Results showed that undergraduates exposing to violent stimuli exhibited high levels of aggression, whereas undergraduates who exposed to non-violent stimuli displayed low levels of aggression. Specifically, males, but not females, manifested high levels of aggression after exposure to violent stimuli. Moreover, viewers with high-aggressiveness (HA), but not with moderate-aggressiveness (MA) and low-aggressiveness (LA), showed high levels of aggression after exposure to violent stimuli via internet.

电力安全文化的参与观察研究

目的:本文探索了电力组织成员共享的价值观与行为规范,探讨电力安全文化的结构;方法:采用参与观察方法对某供电企业进行研究,4名研究者持续观察一个月,记录现场发生的行为及其背景,然后把观察记录整理成情景性行为片段,通过5名专家对现场观察行为进行分类;结果:电力组织成员主要遵循包括:管理效力、人性观、公平公正性、规则执行、工作态度和安全学习等6类行为规范;结论:管理效力、人性观、公平公正性集中反映管理对安全的承诺;规则执行、工作态度和安全学习集中反映员工对安全的承诺。

Electroacupuncture modulates the activity of the hippocampus-nucleus tractus solitarius-vagus nerve pathway to reduce myocardial ischemic injury

The hippocampus is involved in the regulation of the autonomic nervous system,together with the hypothalamus and brainstem nuclei,such as the paraventricular nucleus and nucleus tractus solitarius.The vagus nerve-nucleus tractus solitarius pathway has an important role in cardiovascular reflex regulation.Myocardial ischemia has been shown to cause changes in the autonomic nervous system,affecting the dynamic equilibrium of the sympathetic and vagal nerves.However,it remains poorly understood how the hippocampus communicates with brainstem nuclei to regulate the autonomic nervous system and alleviate myocardial ischemic tissue damage.A rat model of acute myocardial ischemia（AMI） was made by ligating the left anterior descending branch of the coronary artery.Three days before ischemia,the hippocampal CA1 region was damaged.Then,3 days after ischemia,electroacupuncture（EA） at Shenmen（HT7）-Tongli（HT5） was performed（continuous wave,1 m A,2 Hz,duration of 30 minutes）.Cluster analysis of firing patterns showed that one type of neuron was found in rats in the sham and AMI groups.Three types of neurons were observed in the AMI ＋ EA group.Six types of neurons were found in the AMI ＋ EA ＋ Lesion group.Correlation analysis showed that the frequency of vagus nerve discharge in each group was negatively correlated with heart rate（HR）（P 〈 0.05,r =-0.424）,and positively correlated with mean arterial pressure（MAP）（P 〈 0.05,r = 0.40987） and the rate-pressure product（RPP）（P 〈 0.05,r = 0.4252）.The total frequency of the nucleus tractus solitarius discharge in each group was positively correlated with vagus nerve discharge（P 〈 0.01,r = 0.7021）,but not with hemodynamic index（HR： P 〉 0.05,r =-0.03263; MAP： P 〉 0.05,r =-0.08993; RPP： P 〉 0.05,r =-0.03263）.Some neurons（Neuron C） were negatively correlated with vagus nerve discharge,HR,MAP and RPP in the AMI ＋ EA group（vagus nerve discharge： P 〈 0.05,r =-0.87749; HR： P 〈 0.01,r =-0.91902; MAP： P 〈 0.05,r =-0.85691; RPP： P 〈 0.01,r =-0.91902）.Some neurons（Neurons C,D and E） were positively correlated with vagus nerve discharge,HR,MAP and RPP in the AMI ＋ EA ＋ Lesion group（vagus nerve discharge： P 〈 0.01,r = 0.8905,P 〈 0.01,r = 0.9725,P 〈 0.01,r = 0.9054; HR： P 〈 0.01,r = 0.9347,P 〈 0.01,r = 0.9089,P 〈 0.05,r = 0.8247; MAP： P 〈 0.05,r = 0.8474,P 〈 0.01,r = 0.9691,P 〈 0.01,r = 0.9027; RPP： P 〈 0.05,r = 0.8637,P 〈 0.01,r = 0.9407,P 〈 0.01,r = 0.9027）.These findings show that the hippocampus-nucleus tractus solitarius-vagus nerve pathway is involved in the cardioprotective effect of EA at the heart meridian.Some interneurons in the nucleus tractus solitarius may play a particularly important role in the cardiomodulatory process.

In situ Raman spectroscopic quantification of CH4–CO2 mixture: application to fluid inclusions hosted in quartz veins from the Longmaxi Formation shales in Sichuan Basin, southwestern China

We re-evaluate the Raman spectroscopic quantification of the molar ratio and pressure for CH4–CO2 mixtures.Firstly,the Raman quantification factors of CH4 and CO2 increase with rising pressure at room temperature,indicating that Raman quantification of CH4/CO2 molar ratio can be applied to those fluid inclusions(FIs)with high internal pressure(i.e.,>15 MPa).Secondly,the v1(CH4)peak position shifts to lower wavenumber with increasing pressure at constant temperature,confirming that the v1(CH4)peak position can be used to calculate the fluid pressure.However,this method should be carefully calibrated before applying to FI analyses because large discrepancies exist among the reported v1(CH4)-P curves,especially in the highpressure range.These calibrations are applied to CH4-rich FIs in quartz veins of the Silurian Longmaxi black shales in southern Sichuan Basin.The vapor phases of these FIs are mainly composed of CH4 and minor CO2,with CO2 molar fractions from4.4%to 7.4%.The pressure of single-phase gas FI ranges from 103.65 to 128.35 MPa at room temperature,which is higher than previously reported.Thermodynamic calculations supported the presence of extremely high-pressure CH4-saturated fluid(218.03–256.82 MPa at 200°C),which may be responsible for the expulsion of CH4 to adjacent reservoirs.

Lithofacies paleogeography mapping and reservoir prediction in tight sandstone strata: A case study from central Sichuan Basin, China

Sand-rich tight sandstone reservoirs are potential areas for oil and gas exploration. However, the high ratio of sandstone thickness to that of the strata in the formation poses many challenges and uncertainties to traditional lithofacies paleogeography mapping. Therefore, the prediction of reservoir sweet spots has remained problematic in the field of petroleum exploration. This study provides new insight into resolving this problem, based on the analyses of depositional characteristics of a typical modern sand-rich formation in a shallow braided river delta of the central Sichuan Basin, China. The varieties of sand-rich strata in the braided river delta environment include primary braided channels,secondary distributary channels and the distribution of sediments is controlled by the successive superposed strata deposited in paleogeomorphic valleys. The primary distributary channels have stronger hydrodynamic forces with higher proportions of coarse sand deposits than the secondary distributary channels. Therefore, lithofacies paleogeography mapping is controlled by the geomorphology, valley locations, and the migration of channels. We reconstructed the paleogeomorphology and valley systems that existed prior to the deposition of the Xujiahe Formation. Following this, rock-electro identification model for coarse skeletal sand bodies was constructed based on coring data. The results suggest that skeletal sand bodies in primary distributary channels occur mainly in the valleys and low-lying areas,whereas secondary distributary channels and fine deposits generally occur in the highland areas. The thickness distribution of skeletal sand bodies and lithofacies paleogeography map indicate a positive correlation in primary distributary channels and reservoir thickness. A significant correlation exists between different sedimentary facies and petrophysical properties. In addition, the degree of reservoir development in different sedimentary facies indicates that the mapping method reliably predicts the distribution of sweet spots. The application and understanding of the mapping method provide a reference for exploring tight sandstone reservoirs on a regional basis.

Prevalence of and risk factors for postprandial hypotension in older Chinese men

Objective To assess the prevalence of and risk factors for postprandial hypotension （PPH） among old and very old Chinese men. Methods The study included 349 Chinese men aged 65 and older, grouped into two age categories： group 1 （old） included 163 men aged 65 to 80 years; group 2 （very old） included 186 men aged over 80 years. Blood pressure changes after meals were assessed every 15 min by ambulatory blood pressure monitoring. Symptoms after meal ingestion and after standing up and changes in the baseline condition relative to blood pressure changes were observed continuously. Additional baseline data included body mass index, medical history, and medication use Results The prevalence of PPH was 59.3% overall and was significantly higher in group 2 than group 1 （63.4% vs. 54.6%, P 〈 0.05）. In group 2, the prevalence of PPH after breakfast （33.8%） and lunch （32.1%） were higher than that after supper （20.9%）, P 〈 0.05. Hypertension and age were significant risk factors for PPH （OR = 2.188, 95% CI： 1.134-4.223, P = 0.02; OR = 1.86, 95% CI： 1.112-3.11, P = 0.018, respectively）. In contrast, acarbose use was protective against PPH （OR = 0.4, 95% CI： 0.189-0.847, P = 0.017）. The decrease in blood pres- sure during PPH was 20-40 mmHg and the maximum was 90 mmHg. PPH usually occurred at 30-60 min after a meal and lasted 30-120 rnin. Conclusions These findings demonstrate that the prevalence of PPH in men aged over 80 years is significantly higher than those in men aged 65 to 80 years, and the blood pressure decline is also higher for men aged over 80 years. In addition, hypertension and age were main risk factors for PPH in the older men, which suggest that preventing and treating PPH is worthwhile.

High Serum Resistin Level may be an Indicator of the Severity of Coronary Disease in Acute Coronary Syndrome

Objective To investigate the correlation between serum resistin level, cardiovascular risk factors and severity of coronary disease in acute coronary syndrome （ACS）. Methods Alter evaluated by clinical history, electrocardiography, exercise tolerance tests, laboratory tests, and coronary angiography, 220 consecutive patients with suspected chest pain were divided into normal control group, stable angina pectoris （SAP） group, and ACS group, respectively. Baseline clinical characteristics, including height, weight, waist circumference, hip circumference, white blood cell count, high-sensitive C-reactive protein （hsCRP）, total cholesterol, triglyceride, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol, were compared among three groups. ELISA was used to detect serum resistin levels. Pearson＇s correlation coefficient analysis was used to assess association between resistin and other traditional cardiovascular risk factors. Multinomial logistic regression analyses were used to define the relationship between serum resistin level and SAP or ACS. Results Serum resistin level in ACS group （1.18±0.48 μg/L） was significantly higher than that in normal control and SAP groups （0.49±0.40 and 0.66±0.40 μg/L; P〈0.01）. Only in ACS group, increased serum resistin level was significantly correlated with hsCRP （r=0.262, P=0.004） and white blood cell count （r=0.347, P=0.001）. Furthermore, serum resistin levels showed a stepwise increase with the number increase of 〉 50% stenosed coronary vessels. Multinomial logistic regression test demonstrated that serum resistin was a strong risk factor for ACS （OR=29.132, 95 % CI： 10.939-77.581, P〈0.001）. Conclusion These findings suggested the potential role of resistin in atherosclerosis and especially its involvement in ACS.

A review of carbonates as hydrocarbon source rocks: basic geochemistry and oil–gas generation

Carbonates have been known to act as hydrocarbon source rocks, but their basic geochemical and associated hydrocarbon generation characteristics remain not well understood as they occur with argillaceous source rocks in most cases, and the hydrocarbon generation from each rock type is di cult to distinguish, forming one of puzzling issues within the field of petroleum geology and geochemistry. To improve the understanding of this critical issue, this paper reviews recent advances in this field and provides a summary of key areas that can be studied in future. Results show that carbonate source rocks are generally associated with high-salinity environments with low amounts of terrestrial inputs and low dissolved oxygen contents. Petrographically, these source rocks are dark gray or black, fine-grained, stratified, and contain bacterial and algal bioprecursors along with some other impurities. They generally have low organic matter contents, although these can vary significantly in di erent cases(e.g., the total organic carbon contents of marine and lacustrine carbonate source rocks in China are generally 0.1%–1.0% and 0.4%–4.0%, respectively). These rocks contain type I and type II kerogen, meaning there is a lack of vitrinites. This means that assessment of the maturity of the organic matter in these sediments needs to use non-traditional techniques rather than vitrinite reflectance. In terms of molecular geochemistry, carbonate source rocks have typical characteristics indicative of generally reducing and saline environments and lower organism-dominated bioprecursors of organic matter, e.g., high contents of sulfur compounds, low Pr/Ph ratios, and dominance of n-alkanes. Most of the carbonate source rocks are typically dominated by D-type organic facies in an oxidized shallow water mass, although high-quality source rocks generally contain A-and B-type organic facies in saline lacustrine and marine-reducing environments, respectively. The hydrocarbon generation model for the carbonate source rocks can involve early, middle, and late stages, with a diversity of hydrocarbons within these rocks, which can be aggregated, adsorbed, enclosed within minerals, or present as inclusions. This in turn implies that the large-scale hydrocarbon expulsion from these rocks is reliant on brittle deformation caused by external forces. Finally, a number of aspects of these source rocks remain unclear and need further study, including the e ectiveness of carbonates as hydrocarbon source rocks, bioprecursors, and hydrocarbon generation models of carbonate source rock, and the di erences between marine and lacustrine carbonate source rocks.

Occurrence and conceptual sedimentary model of Cambrian gypsum-bearing evaporites in the Sichuan Basin, SW China

During the Cambrian, gypsum-bearing evaporites formed in the Sichuan Basin, SW China. These rocks are important for oil and gas sealing, but details of their distribution and origin are not well established. This study examines the regional distribution and origin of the gypsum-bearing evaporites using a comprehensive analysis of drilling data from 34 wells, 5 measured cross-sections in the basin and surrounding area, and 96 maps of area-survey data. Results show that in the stratigraphic succession, the gypsum-bearing evaporites occur mainly in the Lower Cambrian Longwangmiao Formation, the Middle Cambrian Douposi Formation, and the Middle-Upper Cambrian Xixiangchi Group. Geographically, the rocks are found mainly in the southeastern part of the basin, and the distribution of deposits shows an overall SW-NE trend. The sedimentary environments for evaporite formation were evaporative lagoon and inter-platform basin in a platform setting. Gypsum was generated by the underwater concentration of sea water in a strongly evaporative environment. Both an evaporative restricted platform and a mixeddeposition restricted platform model appear to be applicable to the development of gypsum in the Sichuan Basin. The gypsum-bearing evaporites with the best sealing capacity are located mostly in the southeastern part of the basin. These constraints can be applied directly to regional exploration, and have implications for the regional paleogeography and paleoclimate.

Discovery of shale oil in alkaline lacustrine basins:The Late Paleozoic Fengcheng Formation,Mahu Sag,Junggar Basin,China

A new type of shale oil in alkaline lacustrine sediments has been discovered in the Late Paleozoic Fengcheng Formation,Mahu Sag,Junggar Basin,China.The fine-grained sedimentary rocks deposited in this alkaline lacustrine environment can be divided into four types and eight sub-types:mudstone(with no alkali minerals),including massive dolomitic mudstone,and massive and laminated calcareous mudstone;dolomite,including massive argillaceous dolomite(with alkali minerals),and massive and laminated argillaceous dolomite(with no alkali minerals);evaporites;and pyroclastic rocks.The massive argillaceous dolomite(with alkali minerals)and pyroclastic rocks have the highest shale oil potential,with average oil saturation index(OSI)values of 344.67 and 124.65 mg HC/g TOC,respectively.Shale oil exploration in the representative well MY1 indicates that the Fengcheng Formation is thick and contains abundant natural fractures,brittle minerals,and mobile oil.The entire Fengcheng Formation is oilbearing and contains three concentrated stratigraphic intervals of shale oil(i.e.,sweet spots).Well MY1 indicates that,compared with source rocks developed in marine and sulfate-type saline basins,the fine-grained sedimentary rocks deposited in alkaline lacustrine environments can also have high shale oil potential.The co-existence and regular distribution of conventional and unconventional reservoirs in the Fengcheng Formation indicate that it is an ideal exploration target for multiple resource types.

Data-Driven Microstructure and Microhardness Design in Additive Manufacturing Using a Self-Organizing Map

To design microstructure and microhardness in the additive manufacturing(AM)of nickel(Ni)-based superalloys,the present work develops a novel data-driven approach that combines physics-based models,experimental measurements,and a data-mining method.The simulation is based on a computational thermal-fluid dynamics(CtFD)model,which can obtain thermal behavior,solidification parameters such as cooling rate,and the dilution of solidified clad.Based on the computed thermal information,dendrite arm spacing and microhardness are estimated using well-tested mechanistic models.Experimental microstructure and microhardness are determined and compared with the simulated values for validation.To visualize process-structure-properties(PSPs)linkages,the simulation and experimental datasets are input to a data-mining model-a self-organizing map(SOM).The design windows of the process parameters under multiple objectives can be obtained from the visualized maps.The proposed approaches can be utilized in AM and other data-intensive processes.Data-driven linkages between process,structure,and properties have the potential to benefit online process monitoring control in order to derive an ideal microstructure and mechanical properties.