检索结果-南通市图书馆

基于自组织映射的增材制造中数据驱动式微观组织和显微硬度设计

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Engineering 2019年第4期 295-306页

作者：甘政涛李恒阳 Sarah J.Wolff jennifer l.bennett Gregory Hyatt Gregory J.Wagner 曹简 Wing Kam liu Department of Mechanical Engineering Northwestern University DMG MORI Hoffman Estates

为了在镍基高温合金的增材制造(AM)中设计微观组织和显微硬度,本研究提出了一种新的数据驱动方法,该方法结合了物理模型、实验测量和数据挖掘方法。该模拟基于计算热流体动力学(Ct FD)模型,可以获得热行为、凝固参数(如冷却速度)和凝固... 详细信息

为了在镍基高温合金的增材制造(AM)中设计微观组织和显微硬度,本研究提出了一种新的数据驱动方法,该方法结合了物理模型、实验测量和数据挖掘方法。该模拟基于计算热流体动力学(Ct FD)模型,可以获得热行为、凝固参数(如冷却速度)和凝固层的稀释率。根据计算出的热信息,可利用经过充分测试的力学模型估算枝晶臂间距和显微硬度。通过实验测定试样的微观结构和显微硬度,与模拟值进行比较验证。为了实现过程-组织-性能(PSP)关系的可视化,模拟及实验数据集被输入到数据挖掘模型——自组织映射(SOM)中。在多目标下,工艺参数的设计窗口可以从可视化映射中得到。这种被提出的方法可用于AM和其他数据密集型工艺过程。过程、组织和性能之间的数据驱动联系可能会有利于在线过程监控控制,从而获得理想的微观组织和力学性能。

关键词：增材制造数据科学多重物理建模自组织映射微观组织显微硬度镍基高温合金

Data-driven analysis of process,structure,and properties of additively manufactured Inconel 718 thin walls

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2022年第1期8卷 1168-1182页

作者： lichao Fang lin Cheng jennifer A.Glerum jennifer bennett Jian Cao Gregory J.Wagner Department of Mechanical Engineering Northwestern UniversityEvanstonIL60208USA Department of Materials Science and Engineering Northwestern UniversityEvanstonIL60208USA DMG MORI Hoffman EstatesIL60192USA Department of Mechanical and Materials Engineering Worcester Polytechnic InstituteWorcesterMA01609USA Department of Civil and Mechanical Engineering US Military Acadeemy at West PointWest PointNY10996USA

In additive manufacturing of metal parts,the ability to accurately predict the extremely variable temperature field in detail,and relate it quantitatively to structure and properties,is a key step in predicting part performance and optimizing process *** this work,a finite element simulation of the directed energy deposition(DED)process is used to predict the space-and time-dependent temperature field during the multi-layer build process for Inconel 718 *** thermal model results show good agreement with dynamic infrared images captured in situ during the DED *** relationship between predicted cooling rate,microstructural features,and mechanical properties is examined,and cooling rate alone is found to be insufficient in giving quantitative property *** machine learning offers an efficient way to identify important features from series data,we apply a 1D convolutional neural network data-driven framework to automatically extract the dominant predictive features from simulated temperature *** good predictions of material properties,especially ultimate tensile strength,are obtained using simulated thermal history *** further interpret the convolutional neural network predictions,we visualize the extracted features produced on each convolutional layer and compare the convolutional neural network detected features of thermal histories for high and low ultimate tensile strength cases.A key result is the determination that thermal histories in both high and moderate temperature regimes affect material properties.

关键词： Inconel process additive

Optimizing perioperative Crohn's disease management: Role of coordinated medical and surgical care

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2015年第4期21卷 1182-1188页

作者： jennifer l.bennett Christina Y Ha Jonathan E Efron Susan l Gearhart Mark G lazarev Elizabeth C Wick Department of Surgery The Johns Hopkins University School of MedicineBaltimoreMD 21287United States Division of Gastroenterology the Johns Hopkins University School of MedicineBaltimoreMD 21287United States Division of Digestive Diseases the David Geffen School of Medicine at University of California Los AngelesLos AngelesCA 90095United States

AIM: To investigate rates of re-establishing gastroenterology care, colonoscopy, and/or initiating me-dical therapy after Crohn's disease(CD) surgery at a tertiary care referral ***: CD patients having small bowel or ileocolonic resections with a primary anastomosis between 2009-2012 were identified from a tertiary academic referral center. CD-specific features, medications, and surgical outcomes were abstracted from the medical record. The primary outcome measure was compliance rates with medical follow-up within 4 wk of hospital discharge and surveillance colonoscopy within 12 mo of surgery. RESUlTS: Eighty-eight patients met study inclusion criteria with 92%(n = 81) of patients returning for surgical follow-up compared to only 41%(n = 36) of patients with documented gastroenterology follow-up within four-weeks of hospital discharge, P ly postoperative medical follow-up included younger age, longer length of hospitalization, postoperative biologic use and academic center patients. In the study cohort, 75.0% of patients resumed medical therapy within 12 mo, whereas only 53.4% of patients underwent a colonoscopy within 12 mo of ***: Our study highlights the need for coordinated CD multidisciplinary clinics and structured handoffs among providers to improve of quality of care in the postoperative setting.

关键词： Coordinated care Crohn’s disease Postoperative pro

Mechanistic data-driven prediction of as-built mechanical properties in metal additive manufacturing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2021年第1期7卷 767-778页

作者： Xiaoyu Xie jennifer bennett Sourav Saha Ye lu Jian Cao Wing Kam liu Zhengtao Gan Department of Mechanical Engineering Northwestern UniversityEvanstonILUSA DMG MORI Hoffman EstatesILUSA Theoretical and Applied Mechanics Northwestern UniversityEvanstonILUSA

Metal additive manufacturing provides remarkable flexibility in geometry and component design,but localized heating/cooling heterogeneity leads to spatial variations of as-built mechanical properties,significantly complicating the materials design *** this end,we develop a mechanistic data-driven framework integrating wavelet transforms and convolutional neural networks to predict location-dependent mechanical properties over fabricated parts based on process-induced temperature sequences,i.e.,thermal *** framework enables multiresolution analysis and importance analysis to reveal dominant mechanistic features underlying the additive manufacturing process,such as critical temperature ranges and fundamental thermal *** systematically compare the developed approach with other machine learning *** results demonstrate that the developed approach achieves reasonably good predictive capability using a small amount of noisy experimental *** provides a concrete foundation for a revolutionary methodology that predicts spatial and temporal evolution of mechanical properties leveraging domain-specific knowledge and cutting-edge machine and deep learning technologies.

关键词： additive properties prediction

The effect of gas phase polydimethylsiloxane surface treatment of metallic aluminum particles： Surface characterization and flow behavior

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2017年第1期15卷 92-101页

作者： Bellamarie ludwia jennifer l. Gray Applied Research laboratory The Pennsylvania State University North Atherton Street State College PA 16801 USA Materials Research Institute The Pennsylvania State University USA

Aluminum particles were exposed to gaseous polydimethylsiloxane （PDMS） to produce a hydropho- bic surface coating for enhanced flow and fluidity. Surface retention of the intact PDMS was confirmed through infrared and X-ray photoelectron spectroscopy. Transmission electron microscopy was used to image cross-sections of the treated particles and energy dispersive spectroscopy element maps demon- strated the presence of a surface layer consisting of silicon and oxygen. Density measurements provided evidence for improvements in the Hausner ratio and Carr index of the PDMS-treated aluminum, indicating a reduction in inter-particulate cohesion through increased bulk density. Stability, compressibility, shear, aeration, and permeability of the particles were assessed by powder rheometer. The compressibility was reduced by approximately 32% following surface treatment, revealing a reduction in void space, while Mohr＇s circle analysis and shear testing determined that the extrapolated cohesion value was reduced by approximately 53% and the flow factor at 6 kPa was doubled. Aeration testing showed that the air velocity required to obtain a fluidized bed was on the order of 0.35 mm/s for the treated powder, whereas the raw powder could not be uniformly fluidized. PDMS may be a viable option for the large-scale treatment of aluminum powder for flow applications.

关键词： Aluminum powder Polydimethylsiloxane X-ray photoelectron spectroscopy Diffuse reflectance infrared Fourier transform spectroscopy Flowability FT4 powder rheometer

Perspectives:Gene expression in fisheries management

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Current Zoology 2010年第1期56卷 157-174页

作者： jennifer l.NIElSEN Scott A.PAVEY US Geological Survey Alaska Science Center Department of Biological Sciences Simon Frasier University National Park Service

Functional genes and gene expression have been connected to physiological traits linked to effective production and broodstock selection in aquaculture, selective implications of commercial fish harvest, and adaptive changes reflected in non-commercial fish populations subject to human disturbance and climate change. Gene mapping using single nucleotide polymorphisms （SNPs） to identify functional genes, gene expression （analogue microarrays and real-time PCR）, and digital sequencing technologies looking at RNA transcripts present new concepts and opportunities in support of effective and sustainable fisheries. Genomic tools have been rapidly growing in aquaculture research addressing aspects of fish health, toxicology, and early development. Genomic technologies linking effects in functional genes involved in growth, maturation and life history development have been tied to selection resulting from harvest practices. Incorporating new and ever-increasing knowledge of fish gehomes is opening a different perspective on local adaptation that will prove invaluable in wild fish conservation and management. Conservation of fish stocks is rapidly incorporating research on critical adaptive responses directed at the effects of human dis- turbance and climate change through gene expression studies. Genomic studies of fish populations can be generally grouped into three broad categories： l） evolutionary genomics and biodiversity; 2） adaptive physiological responses to a changing environment; and 3） adaptive behavioral genomics and life history diversity. We review current genomic research in fisheries focusing on those that use microarrays to explore differences in gene expression among phenotypes and within or across populations, information that is critically important to the conservation of fish and their relationship to humans [Current Zoology 56 （1）： 157-174, 2010].

关键词： Fish genome Fisheries management Conservation Gene expression

Frailty is independently associated with increased hospitalisation days in patients on the liver transplant waitlist

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2017年第5期23卷 899-905页

作者： Marie Sinclair Eduard Poltavskiy jennifer l Dodge jennifer C lai Gastroenterology and Hepatology University of CaliforniaSan FranciscoCa 94143United States

AIMTo investigate the impact of physical frailty on risk of hospitalisation in cirrhotic patients on the liver transplant *** listed for liver transplantation at a single centre underwent frailty assessments using the Fried Frailty Index, consisting of grip strength, gait speed, exhaustion, weight loss, and physical activity. Clinical and biochemical data including MElD score as collected at the time of assessment. The primary outcome was number of hospitalised days per year; secondary outcomes included incidence of infection. Univariable and multivariable analysis was performed using negative binomial regression to associate baseline parameters including frailty with clinical outcomes and estimated incidence rate ratios (IRR).RESUlTSOf 587 cirrhotics, 64% were male, median age (interquartile range) was 60 (53-64) years and MElD score was 15 (12-18). Median Fried Frailty Index was 2 (1-3); 31.6% were classified as frail (fried frailty ≥ 3). During 12 mo of follow-up, 43% required at least 1 hospitalisation; 38% of which involved major infection. 107/184 (58%) frail and 142/399 (36%) non-frail patients were hospitalised at least once (P le analysis, Fried Frailty Index was associated with total hospitalisation days per year (IRR = 1.51, 95%CI: 1.28-1.77; P ≤ 0.001), which remained significant on multivariable analysis after adjustment for MElD, albumin, and gender (IRR for frailty of 1.21, 95%CI: 1.02-1.44; P = 0.03). Incidence of infection was not influenced by *** cirrhotics on the liver transplant waitlist, physical frailty is a significant predictor of hospitalisation and total hospitalised days per year, independent of liver disease severity.

关键词： Hospitalisation Infection Cirrhosis Frailty Transplantation

Advancements and challenges in treating advanced gastric cancer in the West

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Oncology 2019年第9期11卷 652-664页

作者： jennifer l leiting Travis E Grotz Division of Hepatobiliary and Pancreas Surgery Mayo Clinic

Gastric cancer is a leading cause of cancer incidence and death *** with advanced gastric cancer benefit from a multi-modality treatment *** oncologic resection with negative margins and complete lymphadenectomy plays a crucial role in long-term survival for patients with resectable *** utilization of minimally invasive techniques for gastric cancer has been slowly increasing and is proving to be both technically and oncologically *** chemotherapy is the current standard of care for advanced gastric cancer.A variety of chemotherapy regimens have been used with the combination of docetaxel,oxaliplatin,5-fluorouracil,and leucovorin being the current recommendation given its superior ability to induce a complete pathologic response and prolong *** use of radiation has been more controversial with its optimal place in the treatment sequence being *** are current ongoing studies assessing the impact of radiation as an adjunct or in place of *** treatments(e.g.,trastuzumab for human epidermal growth factor receptor 2 positive tumors and pembrolizumab for programmed death-ligand 1 positive tumors)are showing promise and are part of a continued emphasis on individualized *** chemotherapy may also play a role in preventing peritoneal recurrences for patients with high risk *** treatment of patients with advanced gastric cancer in the West continues to advance and improve with a better understanding of optimal treatment sequences and the utilization of personalized treatment regimens.

关键词： Gastric cancer D2 lymphadenectomy Minimally invasive surgery Neoadjuvant chemotherapy Chemoradiation Targeted treatments

The hydrologic record of karst systems: linking soil moisture to the carbon isotope signatures of soils above the Blue Spring cave system

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geochimica 2017年第3期36卷 392-395页

作者： Yuchen liu Jessica l.Oster jennifer l.Druhan Department of Geology University of Illinois Urbana Champaign Department of Earth and Environmental Science Vanderbilt University

Speleothem carbonates are precipitated continuously from inorganic carbon dissolved in seepage water infiltrating from the land surface,that reflects a mixture of atmospheric CO_2,respired soil carbon,and epikarst sources,each with distinct δ^(13)C *** aid in deconvolving these signatures,soil samples were collected above the Blue Spring cave system in Sparta,Tennessee,USA and subjected to a series of incubation experiments,in order to constrain the correlation between CO_2respiration rates and soil *** relationship is used to parameterize a simple mixing model which predicts the relationship between δ^(13)C and soil moisture in fluids infiltrating into the underlying cave system.

关键词： Speleothem δ^13C CO2 respiration Soil moisture