The heat treatment of a metal is a set of heating and cooling cycles that a metal undergoes to change its microstructure and, therefore, its properties. Temperature–time–transformation (TTT) diagrams are an essential tool for interpreting the resulting microstructures after heat treatments. The present work describes a novel proposal to predict TTT diagrams of the phase for the Ni-Al alloy using artificial neural networks (ANNs). The proposed methodology is composed of five stages: (1) database creation, (2) experimental design, (3) ANNs training, (4) ANNs validation, and (5) proposed models analysis. Two approaches were addressed, the first to predict only the nose point of the TTT diagrams and the second to predict the complete curve. Finally, the best models for each approach were merged to compose a more accurate hybrid model. The results show that the multilayer perceptron architecture is the most efficient and accurate compared to the simulated TTT diagrams. The prediction of the nose point and the complete curve showed an accuracy of % and %, respectively. The proposed final hybrid model achieves an accuracy of %. 相似文献
Earth materials have been used in construction as safe, healthy and environmentally sustainable. It is often challenging to develop an optimum soil mix because of the significant variations in soil properties from one soil to another. The current study analyzed the soil properties, including the grain size distribution, Atterberg limits, compaction characteristics, etc., using multilinear regression (MLR) and artificial neural networks (ANN). Data collected from previous studies (i.e., 488 cases) for stabilized (with either cement or lime) and unstabilized soils were considered and analyzed. Missing data were estimated by correlations reported in previous studies. Then, different ANNs were designed (trained and validated) using Levenberg-Marquardt (L-M) algorithms. Using the MLR, several models were developed to estimate the compressive strength of both unstabilized and stabilized soils with a Pearson Coefficient of Correlation (R2) equal to 0.2227 and 0.766, respectively. On the other hand, developed ANNs gave a higher value for R2 than MLR (with the highest value achieved at 0.9883). Thereafter, an experimental program was carried out to validate the results achieved in this study. Finally, a sensitivity analysis was carried out using the resulting networks to assess the effect of different soil properties on the unconfined compressive strength (UCS). Moreover, suitable recommendations for earth materials mixes were presented. 相似文献
目的比较单腔气管插管和双腔气管插管在微创食管癌根治术中近期效果的差异。方法回顾性分析福建省立医院胸外科2014年1月~2015年12月接受微创Mckeown术的94例食管癌患者的临床资料。结果单腔插管组术中出血显著少于双腔插管组(205.6±62.1 mL vs 277.9±219.9 mL,P=0.028),左喉返神经旁淋巴结清扫数(3.4±5.5 vs 1.2±2.5,P=0.043)和纵隔淋巴结清扫数(19.1±14.2 vs 13.7±9.2,P=0.037)显著多于双腔插管组。两组手术时间、右喉返神经旁淋巴结清扫数、淋巴结清扫总数、平均住院时间、平均住ICU时间及术后并发症的发生率的差异无统计学意义。结论单腔气管插管具有费用低、操作简单、术野显露好的特点,有助于纵隔淋巴结的清扫和减少术中出血,其近期效果优于双腔支气管插管。相似文献
The multi-stage roll die forming (RDF) process is a plastic forming process that can manufacture a transmission part with a complex shape, such as a drum clutch, by using a die set with rotational rolls. However, it is difficult to satisfy dimensional accuracy because of spring-back and unfilling. The purpose of this study is to design a multi-stage RDF process for the manufacturing of a drum clutch to improve dimensional accuracy using an artificial neural network (ANN). Finite element (FE) simulation of the multi-stage RDF process is performed to predict the dimensional accuracy according to various clearances for each stage. Moreover, the ANN is used to determine the relationship between the clearance and dimensional accuracy of the drum clutch to reduce the number of FE simulation. The results of the FE simulation and ANN are used to determine the optimal clearance for each stage of the RDF process. Finally, the drum clutch is fabricated using the determined conditions. The experimental results are in good agreement with the results of FE simulation from the aspect of outer diameter, inner diameter, thickness of outer tooth, thickness of inner tooth, and face thickness of tooth. 相似文献
Objective: To determine the efficacy of electroejaculation in combination with assisted reproductive technology (ART).
Design: Case series.
Setting: University fertility program.
Patient(s): One hundred twenty-one consecutive couples seeking treatment of anejaculatory infertility.
Intervention(s): Electroejaculation with IUI, or gamete intrafallopian transfer or IVF.
Main Outcome Measure(s): Pregnancy and pregnancy outcome.
Result(s): Fifty-two couples became pregnant (43%), 39 by IUI alone (32.2%). Cycle fecundity for IUI was 8.7%. No difference in cycle fecundity was seen among ovarian stimulation protocols (clomiphene citrate, 7.6%, hMG, 13.2%, and natural cycle, 11.2%). Pregnancy was unlikely when the inseminated motile sperm count was <4 million. Female management protocol and etiology of anejaculation did not affect results. Patients undergoing IVF had higher cycle fecundity (37.2%) than did those undergoing IUI. The rates of spontaneous abortion and multiple gestations were 23% and 12%, respectively.
Conclusion(s): Electroejaculation with stepwise application of ART is effective in treating anejaculatory infertility. Intrauterine insemination with the least expensive monitoring protocol should be used for most couples, because use of more expensive monitoring did not improve results. It is cost-effective to bypass IUI and proceed directly to IVF in men who require anesthesia for electroejaculation and in those with a total inseminated motile sperm count < 4 million. 相似文献
Artificial intelligence holds great promise for improved health‐care outcomes. But it also poses substantial new hazards, including algorithmic discrimination. For example, an algorithm used to identify candidates for beneficial “high risk care management” programs routinely failed to select racial minorities. Furthermore, some algorithms deliberately adjust for race in ways that divert resources away from minority patients. To illustrate, algorithms have underestimated African Americans’ risks of kidney stones and death from heart failure. Algorithmic discrimination can violate Title VI of the Civil Rights Act and Section 1557 of the Affordable Care Act when it unjustifiably disadvantages underserved populations. This article urges that both legal and technical tools be deployed to promote AI fairness. Plaintiffs should be able to assert disparate impact claims in health‐care litigation, and Congress should enact an Algorithmic Accountability Act. In addition, fairness should be a key element in designing, implementing, validating, and employing AI. 相似文献