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小尺寸CT试样断裂行为的GTN细观损伤模型研究 被引量:1
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作者 杨越 李逸涵 +4 位作者 杨万欢 黎军顽 钟巍华 宁广胜 杨文 《原子能科学技术》 EI CAS CSCD 北大核心 2024年第2期411-420,共10页
基于国产A508-Ⅲ钢的单轴拉伸测试,构建了Ramberg-Osgood力学本构模型和GTN(Gurson-Tvergaard-Needleman)细观损伤模型,并对模型参数进行了标定,开展了不同温度下小尺寸CT(1/6CT)试样的断裂韧性测试,采用规则化方法计算得到裂纹扩展阻... 基于国产A508-Ⅲ钢的单轴拉伸测试,构建了Ramberg-Osgood力学本构模型和GTN(Gurson-Tvergaard-Needleman)细观损伤模型,并对模型参数进行了标定,开展了不同温度下小尺寸CT(1/6CT)试样的断裂韧性测试,采用规则化方法计算得到裂纹扩展阻力曲线(J-R曲线),分析了测试温度对材料断裂性能的影响。结果表明,随着温度从-100℃度降低至-130℃,断口韧窝区的宽度由43μm缩减至10μm,平均韧窝尺寸从0.3μm缩小至0.05μm,材料的塑性变形能力随着温度的降低而脆化。基于构建的力学本构模型和GTN细观损伤模型,采用有限元法分析了1/6CT试样从裂纹萌生、扩展至失效断裂的过程。结果表明,J-R曲线随着温度的下降而降低,断裂韧性(J_(IC)值)和裂纹扩展量(Δa)的降幅分别为43%和3%,相对误差不超过5%。这表明,基于GTN细观损伤模型的数值方法是研究小尺寸CT试样断裂行为的一种简便、有效的方法。 展开更多
关键词 国产A508-Ⅲ钢 gtn细观损伤模型 小尺寸CT试样 断裂韧性 J-R曲线
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15-15Ti奥氏体不锈钢热老化小尺寸试样单轴拉伸行为的GTN微观损伤模型研究
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作者 李帅 张子诚 +2 位作者 黎军顽 宁广胜 钟巍华 《上海金属》 CAS 2024年第3期67-74,82,共9页
通过加速热老化试验模拟了15-15Ti奥氏体不锈钢的辐照效应,构建了Ramberg-Osgood力学本构模型和GTN(Gurson-Tvergaard-Needleman)微观损伤模型。结合有限元方法,探讨了热老化不同时间的15-15Ti奥氏体不锈钢小尺寸试样在不同温度拉伸试... 通过加速热老化试验模拟了15-15Ti奥氏体不锈钢的辐照效应,构建了Ramberg-Osgood力学本构模型和GTN(Gurson-Tvergaard-Needleman)微观损伤模型。结合有限元方法,探讨了热老化不同时间的15-15Ti奥氏体不锈钢小尺寸试样在不同温度拉伸试验过程中的应力-应变响应行为和损伤断裂过程。结果表明:热老化小尺寸试样中有少量碳化物析出和大量σ相形成,导致其抗拉强度和屈服强度显著下降;未热老化试样的拉伸断口中有大量韧窝,为韧性断裂,而热老化试样的拉伸断口中韧窝数量明显减少,析出相周围有撕裂棱,为脆性断裂;热老化试样标距段的应力集中和颈缩均延迟发生;热老化试样的断裂应变明显小于未热老化试样;热老化能促使小尺寸试样中孔洞的聚集和增多,从而加速失效。 展开更多
关键词 15-15Ti 奥氏体不锈钢 小尺寸试样 热老化 gtn 模型
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DP780双相钢剪切修正GTN模型损伤参数确定
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作者 孙彩凤 李迪 孟令韩 《精密成形工程》 北大核心 2024年第8期190-196,共7页
目的为了准确预测DP780双相钢在低应力三轴度时出现的剪切断裂,建立了损伤参数与断裂时载荷和位移的响应面模型,并根据此模型研究损伤参数变化对双相钢剪切断裂的影响,得到最佳损伤参数,以提高预测双相钢发生断裂的精确性。方法以DP780... 目的为了准确预测DP780双相钢在低应力三轴度时出现的剪切断裂,建立了损伤参数与断裂时载荷和位移的响应面模型,并根据此模型研究损伤参数变化对双相钢剪切断裂的影响,得到最佳损伤参数,以提高预测双相钢发生断裂的精确性。方法以DP780为研究对象,建立了剪切修正GTN模型,以孔洞体积分数fN、孔洞形核时平均应变εN、剪切系数kw为因素,分别以断裂时载荷和位移为响应值,基于试验设计得到对应的响应函数,并在此基础上建立误差评价函数,通过最小二乘法对误差评价函数进行求解得到最佳损伤参数。结果建立了基于断裂载荷和位移的误差评价函数,在此基础上结合试验验证,确定fN=0.025、εN=0.198、kw=2是最佳损伤参数组合。孔洞体积分数和剪切系数对断裂影响较大,随着孔洞体积分数fN的增大,发生断裂时的载荷减小,随着剪切系数kw的增大,发生断裂时的位移缩短。结论基于Abaqus软件,建立了剪切试样有限元模型并对其进行断裂仿真,断裂时平均减薄率为1.4%,与断裂试验结果吻合,表明了获得的损伤参数的准确性,为双相钢在车身结构件中的生产应用提供理论依据。 展开更多
关键词 双相钢 剪切修正gtn 损伤参数 断裂失效
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基于GTN模型的2195铝锂合金板材反复弯曲成形特性及变形损伤
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作者 贾向东 赵鑫 +3 位作者 镐昆明 范振宇 罗展 匡靖胤 《塑性工程学报》 CAS CSCD 北大核心 2024年第6期1-14,共14页
以商用2195-T6铝锂合金板材为研究对象,借助单向拉伸试验,获得了其真应力-真应变曲线;以此为基础,建立了能够表征2195铝锂合金变形损伤的GTN模型和反复弯曲成形的数值仿真模型,对反复弯曲成形过程中弯曲次数和压下量对板材的回弹和损伤... 以商用2195-T6铝锂合金板材为研究对象,借助单向拉伸试验,获得了其真应力-真应变曲线;以此为基础,建立了能够表征2195铝锂合金变形损伤的GTN模型和反复弯曲成形的数值仿真模型,对反复弯曲成形过程中弯曲次数和压下量对板材的回弹和损伤特征的影响进行分析,并通过试验验证了反复弯曲对回弹的影响。结果表明:在单次弯曲变形中,随着弯曲压下量的增加,塑性弯曲变形区逐渐增大;当压下量大于临界值时,随着压下量的增加,回弹量逐渐减小。在相同的压下量条件下,随着弯曲次数增加,板材的塑性变形区逐渐增加,回弹量逐渐减小;但是随着弯曲次数的增加,板材的损伤逐渐增大,因此,通过反复弯曲成形抑制弯曲回弹需要将板材的内部损伤控制在许可范围内。 展开更多
关键词 gtn模型 铝锂合金 成形性能 弯曲成形 塑性损伤
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Pregnancy and Obstetrical Outcomes Following Treatment for Cervical Intra-Epithelial Neoplasia (CIN) in Two Hospitals of a Low-Resource Country
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作者 Bruno Kenfack Clovis-Achille Tanekeu +3 位作者 Atem Bethel Ajong Zabdielle Blonde Goufack Kenfack Patrick Petignat Pierre Marie Tebeu 《Advances in Reproductive Sciences》 CAS 2024年第1期51-59,共9页
Objective: In Cameroon, more than 80% of women suffering from cervical intraepithelial neoplasia (CIN) are within the reproductive age. This study intended to analyze the pregnancy outcomes following cervical treatmen... Objective: In Cameroon, more than 80% of women suffering from cervical intraepithelial neoplasia (CIN) are within the reproductive age. This study intended to analyze the pregnancy outcomes following cervical treatment in Cameroon. Methods: This was a cohort study with two years retrospective data collection involving 82 women who underwent cervical treatment for CIN in two Cameroonian hospitals from January 2015 to December 2017. Data were collected from CIN treatment to end of pregnancy where applicable. Data analysis was done using Epi Info software version 3.5.4. Results: We collected data from 82 patients aged 27 to 48 years, with a mean age of 36.5 (SD: 5.3) years. During the study period, 33 out of 82 participants became pregnant 40.2 [29.56 - 51.66]%. The factor associated with pregnancy occurrence after treatment was age less than 35 years (Odds ratio = 4.37 [1.7 - 11.2]. From the 33 pregnancies recorded, 17 (51.5%) ended in a delivery, amongst which 15 (88.2%) were vaginal. Conclusion: Pregnancy frequency over two years following cervical treatment for CIN was relatively good, and younger women (age 35 years) were significantly more like to have conceived compared to their older counterparts. Post-treatment delivery outcomes seem to be similar to those in the general population. 展开更多
关键词 Cervical Intraepithelial neoplasia Cervical Treatment Pregnancy Outcome
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Early detection of multiple endocrine neoplasia type 1: A case report
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作者 Jie-Hao Yuan Su Luo +1 位作者 Ding-Guo Zhang Li-Sheng Wang 《World Journal of Gastroenterology》 SCIE CAS 2024年第26期3247-3252,共6页
BACKGROUND Multiple endocrine neoplasias(MENs)are a group of hereditary diseases invol-ving multiple endocrine glands,and their prevalence is low.MEN type 1(MEN1)has diverse clinical manifestations,mainly involving th... BACKGROUND Multiple endocrine neoplasias(MENs)are a group of hereditary diseases invol-ving multiple endocrine glands,and their prevalence is low.MEN type 1(MEN1)has diverse clinical manifestations,mainly involving the parathyroid glands,gastrointestinal tract,pancreas and pituitary gland,making it easy to miss the clinical diagnosis.CASE SUMMARY We present the case of a patient in whom MEN1 was detected early.A middle-aged male with recurrent abdominal pain and diarrhea was admitted to the hos-pital.Blood tests at admission revealed hypercalcemia and hypophosphatemia,and emission computed tomography of the parathyroid glands revealed a hy-perfunctioning parathyroid lesion.Gastroscopy findings suggested a duodenal bulge and ulceration.Ultrasound endoscopy revealed a hypoechoic lesion in the duodenal bulb.Further blood tests revealed elevated levels of serum gastrin.Surgery was performed,and pathological analysis of the surgical specimens revealed a parathyroid adenoma after parathyroidectomy and a neuroendocrine tumor after duodenal bulbectomy.The time from onset to the definitive diagnosis of MEN1 was only approximately 1 year.CONCLUSION For patients who present with gastrointestinal symptoms accompanied by hyper-calcemia and hypophosphatemia,clinicians need to be alert to the possibility of MEN1. 展开更多
关键词 Multiple endocrine neoplasia type 1 Gastrointestinal symptoms Hypercal-cemia Early detection Case report
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C634Y mutation in RET-induced multiple endocrine neoplasia type 2A:A case report
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作者 Hui-Fen Zhang Shu-Ling Huang +3 位作者 Wen-Li Wang Yu-Qing Zhou Jun Jiang Zhuo-Jin Dai 《World Journal of Clinical Cases》 SCIE 2024年第15期2627-2635,共9页
BACKGROUND Multiple endocrine neoplasia type 2(MEN2)is a rare,autosomal dominant endocrine disease.Currently,the RET proto-oncogene is the only gene implicated in MEN2A pathogenesis.Once an RET carrier is detected,fam... BACKGROUND Multiple endocrine neoplasia type 2(MEN2)is a rare,autosomal dominant endocrine disease.Currently,the RET proto-oncogene is the only gene implicated in MEN2A pathogenesis.Once an RET carrier is detected,family members should be screened to enable early detection of medullary thyroid carcinoma,pheochromocytoma,and hyperparatitity.Among these,medullary thyroid carcinoma is the main factor responsible for patient mortality.Accordingly,delineating strategies to inform clinical follow-up and treatment plans based on genes is paramount for clinical practitioners.CASE SUMMARY Herein,we present RET proto-oncogene mutations,clinical characteristics,and treatment strategies in a family with MEN2A.A family study was conducted on patients diagnosed with MEN2A.DNA was extracted from the peripheral blood of family members,and first-generation exon sequencing of the RET protooncogene was conducted.The C634Y mutation was identified in three family members spanning three generations.Two patients were sequentially diagnosed with pheochromocytomas and bilateral medullary thyroid carcinomas.A 9-yearold child harboring the gene mutation was diagnosed with medullary thyroid carcinoma.Surgical resection of the tumors was performed.All family members were advised to undergo complete genetic testing related to the C634Y mutation,and the corresponding treatments administered based on test results and associated clinical guidelines.CONCLUSION Advancements in MEN2A research are important for familial management,assessment of medullary thyroid cancer invasive risk,and deciding surgical timing. 展开更多
关键词 Multiple endocrine neoplasia type 2A MUTATION RET proto-oncogene Medullary thyroid carcinoma PHEOCHROMOCYTOMA Case report
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Adverse Pregnancy Outcomes Following Cryotherapy, Thermal Ablation and Loop Electrosurgical Excision Procedure for Cervical Intraepithelial Neoplasia Treatment: A Pilot Study among Zambian Women
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作者 Victoria Mwiinga-Kalusopa Johanna E. Maree +1 位作者 Concepta Kwaleyela Patricia Katowa-Mukwato 《Open Journal of Obstetrics and Gynecology》 2024年第1期7-17,共11页
Background: Cervical Intraepithelial neoplasia treatments have become essential interventions to manage cervical lesions. Majority of the recipients of these treatments are women within the reproductive age group, who... Background: Cervical Intraepithelial neoplasia treatments have become essential interventions to manage cervical lesions. Majority of the recipients of these treatments are women within the reproductive age group, who according to literature may be at risk of adverse pregnancy outcomes. This pilot study is part of a study investigating adverse pregnancy outcomes among women who received Cryotherapy, Thermal ablation and Loop Electrosurgical Excision Procedure compared to the untreated women in Zambia. Materials and Methods: This descriptive study analyzed records of 886 (n = 443 treated and n = 443 untreated) women aged 15 - 49 years. The women were either screened with Visual Inspection with Acetic Acid or treated for Cervical Intraepithelial neoplasia at the Adult Infectious Disease Centre between January 2010 and December 2020. Women meeting the criteria were identified using the Visual Inspection with Acetic Acid screening records and telephone interviews to obtain the adverse pregnancy outcome experienced. Data were analysed using STATA version 16 to determine the prevalence and obtain frequency distribution of outcomes of interest. Univariate and multivariable binary logistic regression estimated odds of adverse pregnancy outcomes across the three treatments. Results: The respondents were aged 15 to 49 years. Adverse pregnancy outcomes were observed to be more prevalent in the treatment group (18.5%) compared to the untreated group (5.4%). Normal pregnancy outcomes were lower in the treated (46.3%;n = 443) than the untreated (53.7%;n = 443). The treated group accounted for the majority of abortions (85.2%), prolonged labour (85.7%) and low birth weight (80%), whereas, the untreated accounted for the majority of still births (72.7%). Women treated with cryotherapy (aOR = 2.43, 95% CI = 1.32 - 4.49, p = 0.004), thermal ablation (aOR = 6.37, 95% CI = 0.99 - 41.2, p = 0.052) and Loop Electrosurgical Excision Procedure (aOR = 9.67, 95% CI = 2.17 - 43.1, p = 0.003) had two-, six- and ten-times higher odds of adverse pregnancy outcomes respectively, relative to women who required no treatment. Conclusion: Adverse pregnancy outcomes are prevalent among women who have received treatment in Zambia. The findings indicate that treating Cervical Intraepithelial Neoplasia has been linked to higher chances of experiencing abortion, delivering low birth weight babies and enduring prolonged labor that may result in a caesarean section delivery. Cervical neoplasia treatments, particularly Loop Electrosurgical Excision Procedure, are associated with significantly increased odds of adverse pregnancy outcomes. It is essential to include information about prior Cervical Intraepithelial neoplasia treatment outcomes in obstetric care. 展开更多
关键词 Adverse Pregnancy Outcomes Cervical Intraepithelial neoplasia Cryothera-py Thermal Ablation Loop Electrosurgical Excision Procedure PILOT Repro-ductive Age
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Molecular diagnostic approaches in detecting rearranged during transfection oncogene mutations in multiple endocrine neoplasia type 2
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作者 Sambasivam Gopinath Velmurugan Ramaiyan 《World Journal of Clinical Cases》 SCIE 2024年第31期6436-6440,共5页
Different types of neuroendocrine cancer,including medullary thyroid cancer(MTC)and thyroid C-cell hyperplasia,are part of multiple endocrine neoplasia type 2(MEN2).A proto-oncogene mutation of the rearranged during t... Different types of neuroendocrine cancer,including medullary thyroid cancer(MTC)and thyroid C-cell hyperplasia,are part of multiple endocrine neoplasia type 2(MEN2).A proto-oncogene mutation of the rearranged during transfection(RET)gene changes the way that receptor tyrosine kinases work.Multiple endocrine neoplasia,a pathological condition,involves these kinases.When the RET protooncogene changes,it can cause endocrine adenomas and hyperplasia to happen at the same time or one after the other.Pheochromocytoma,medullary thyroid carcinoma,and hyperparathyroidism,alone or in combination,are present in MEN2A patients.Some patients may also have skin lichen amyloidosis or Hirschsprung's disease.Patients with MEN2A often present with MTC.MTC is aggressive and has the worst prognosis,as most patients exhibit lymph node metastasis.MTC is one of the important causes of death in patients with MEN2A.RET mutation analysis aids in identifying MEN2A symptoms and monitoring levels of calcium,thyroid hormones,calcitonin,normetanephrine,fractionated metanephrines,and parathyroid hormone.The earlier diagnosis of MTC significantly improves survival and prompts better management of MEN2A.In this editorial,we will discuss the significance of molecular diagnostic approaches in detecting RET oncogene mutations in MEN2A. 展开更多
关键词 Multiple endocrine neoplasia type 2 Medullary thyroid cancer PHEOCHROMOCYTOMA THYROIDECTOMY Rearranged during transfection
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5083铝合金GTN损伤参数求解与成形极限预测
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作者 刘纯国 王廖子 姚作杨 《中南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2023年第11期4315-4325,共11页
GTN(Gurson-Tvergaard-Needleman)损伤模型被广泛用于预测金属的韧性断裂,但损伤参数多且求解困难,限制了其实际应用。以5083铝合金为研究对象,通过扫描电镜观察不同变形阶段拉伸试样的孔洞体积占比确定GTN损伤参数的取值范围;借助中心... GTN(Gurson-Tvergaard-Needleman)损伤模型被广泛用于预测金属的韧性断裂,但损伤参数多且求解困难,限制了其实际应用。以5083铝合金为研究对象,通过扫描电镜观察不同变形阶段拉伸试样的孔洞体积占比确定GTN损伤参数的取值范围;借助中心复合实验设计方法构造拉伸曲线关键变量与GTN损伤参数的响应曲面模型,应用NSGA-II遗传算法优化铝合金板料的损伤参数;将优化后的GTN损伤参数应用于有限元分析中,利用数值模拟方法预测5083铝合金的成形极限图(FLD),并通过Nakazima试验测得铝合金板料的FLD,与数值模拟结果进行对比分析。研究结果表明:GTN损伤模型预测的FLD与实验结果的相对误差在10%以内,且拉压变形区域的预测精度高于双拉变形区域的预测精度。 展开更多
关键词 5083铝合金 gtn损伤模型 成形极限图 响应曲面法
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一种新的耦合GTN模型以精确识别金属板料极限应变的三维M-K模型 被引量:1
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作者 王玉宝 张存生 +2 位作者 孟子杰 陈良 赵国群 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2023年第7期1953-1962,共10页
为了精确识别金属板料的极限应变并提高成形极限预测精度,建立了一种新的耦合GTN模型的三维M-K模型,并命名为三维M-K-GTN模型。首先,通过引入摩擦应力和沿厚度方向上的法向应力,对经典M-K模型进行修正以使其适用于三维应力状态。随后,嵌... 为了精确识别金属板料的极限应变并提高成形极限预测精度,建立了一种新的耦合GTN模型的三维M-K模型,并命名为三维M-K-GTN模型。首先,通过引入摩擦应力和沿厚度方向上的法向应力,对经典M-K模型进行修正以使其适用于三维应力状态。随后,嵌入GTN模型以取代经验失效准则,将凹槽内孔洞体积分数累积到临界值时的应变作为极限应变。此外,考虑法向应力和摩擦应力,修正了孔洞形核与长大表达式。最后,预测成形极限曲线与实验获得的AA6016-T4板料极限应变的对比结果表明,三维M-K-GTN模型解决了大应变路径下预测结果明显高估的问题,且在每个给定的应变路径下都具有较高的预测精度。 展开更多
关键词 极限应变识别 孔洞演化 失效准则 三维M-K-gtn模型 预测精度
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基于GTN模型的含缺陷球墨铸铁力学行为分析
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作者 匡锐 巩红涛 +5 位作者 刘嘉欣 张威 李明 邓雪涛 刘军 耿小亮 《热加工工艺》 北大核心 2023年第11期131-135,共5页
利用有限元反向标定法得到Gurson-Tvergaard-Needleman(GTN)损伤模型的参数,并基于GTN模型模拟含缺陷QT500球墨铸铁的单轴拉伸变形过程,提出了描述材料内部缩松分散度的正态分布函数,以描述其对力学性能的影响。结果表明,GTN损伤模型可... 利用有限元反向标定法得到Gurson-Tvergaard-Needleman(GTN)损伤模型的参数,并基于GTN模型模拟含缺陷QT500球墨铸铁的单轴拉伸变形过程,提出了描述材料内部缩松分散度的正态分布函数,以描述其对力学性能的影响。结果表明,GTN损伤模型可准确地反映球墨铸铁材料的损伤演化。随着孔隙率分布函数方差的增大,孔隙率的分布变广,使材料承载性能下降。 展开更多
关键词 gtn模型 球墨铸铁 损伤模型参数 内部缺陷
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基于GTN损伤模型的均质平板非共线平行双裂纹合并方式研究
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作者 刘红侠 杨杰 +3 位作者 刘芳 沈鋆 王骁晓 陈浩峰 《压力容器》 北大核心 2023年第6期50-62,共13页
为了对裂纹合并方式进行系统性研究,以均质平板中非共线平行双裂纹为研究对象,基于Gurson-Tvergaard-Needleman(GTN)损伤模型,结合试验,对双裂纹不同水平距离s(从0~1 mm)和垂直距离h(从0.4~2.0 mm)组合下,49个模型的合并方式进行研究。... 为了对裂纹合并方式进行系统性研究,以均质平板中非共线平行双裂纹为研究对象,基于Gurson-Tvergaard-Needleman(GTN)损伤模型,结合试验,对双裂纹不同水平距离s(从0~1 mm)和垂直距离h(从0.4~2.0 mm)组合下,49个模型的合并方式进行研究。并以双裂纹水平距离s与裂纹长度a的比值为横坐标,双裂纹垂直距离h与裂纹长度a的比值为纵坐标绘制图形,对双裂纹合并规律进行了探索。结果表明:非共线平行双裂纹呈现出裂尖与裂尖合并、裂间与裂间合并以及裂尖与裂间合并3种合并方式,且各有特征。在以s/a和h/a为坐标绘制的图形中,3种裂纹合并方式有规律地分布在3个区域。在左上角h/a较大、s/a较小的区域发生裂尖与裂间合并,在右下角h/a较小、s/a较大的区域发生裂尖与裂尖合并,在中间区域发生裂间与裂间合并,可根据该图方便地确定裂纹合并方式。3种合并方式中,发生裂尖与裂尖合并的概率约占50%,发生裂间与裂间合并、裂尖与裂间合并的概率分别约占30%和20%。 展开更多
关键词 双裂纹 gtn损伤模型 合并方式 合并规律
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基于GTN和CDM的5754铝合金板材成形极限曲线和失效行为对比分析 被引量:1
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作者 周彬 王成 +2 位作者 汪森辉 陶欣荣 苏奇 《塑性工程学报》 CAS CSCD 北大核心 2023年第10期135-143,共9页
为探究基于不同物理机制的损伤模型对材料可成形性预测的影响,分别采用Gurson-Tvergaard-Needleman(GTN)细观损伤模型和基于热力学的连续介质损伤力学(CDM)模型对5754铝合金板材的成形极限曲线和失效行为进行了对比分析。首先,建立了575... 为探究基于不同物理机制的损伤模型对材料可成形性预测的影响,分别采用Gurson-Tvergaard-Needleman(GTN)细观损伤模型和基于热力学的连续介质损伤力学(CDM)模型对5754铝合金板材的成形极限曲线和失效行为进行了对比分析。首先,建立了5754铝合金板材单向拉伸有限元模型,对照实验结果验证了GTN细观损伤模型和基于热力学的CDM模型在表征材料力学行为上的有效性。其次,开展了不同宽度尺寸板材试样的胀形有限元模拟,提取破坏位置的主应变和次应变,绘制5754铝合金板材的成形极限。结果表明,GTN细观损伤模型预测的成形极限曲线与实验数据吻合较好,但基于热力学的CDM模型不能准确地反映成形极限曲线中材料点拉-压力学特征与拉-拉力学特征之间的区别。最后,利用基于GTN和CDM的成形极限曲线预测5754铝合金在十字拉深成形过程中的损伤分布和失效行为,结果表明,两种基于不同机制的损伤模型都能够有效地预测5754铝合金的可成形性,预测结果与实验现象具有很好的一致性。 展开更多
关键词 5754铝合金 gtn细观损伤模型 连续介质损伤力学模型 成形极限曲线 数值模拟
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Distribution of High-Risk Human Papillomavirus Genotypes among Women with Colposcopic Diagnosis of Cervical Intraepithelial Neoplasia in Bangladesh
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作者 Siddika Mosammat Shahida Mina Chowdhury +4 位作者 Fatima Shajahan Jannat Ara Rifat Alfi Sharin Lubaba S. M. Shamsuzzaman Annekathryn Goodman 《Journal of Cancer Therapy》 2023年第6期277-290,共14页
Background: The incidence of cervical cancer is high in Bangladesh and there is a high prevalence of preinvasive lower genital tract disease among women of reproductive age. Persistent high-risk Human Papilloma Virus ... Background: The incidence of cervical cancer is high in Bangladesh and there is a high prevalence of preinvasive lower genital tract disease among women of reproductive age. Persistent high-risk Human Papilloma Virus (HPV) infection is the main underlying cause of cervical cancer and its precursor, cervical intraepithelial neoplasia (CIN). Objective: The aim of the study was to identify the subtypes of high-risk HPV infection among women with the colposcopic diagnosis of cervical intraepithelial neoplasia in Bangladesh. Methods: This cross-sectional observational study was conducted in the colposcopy clinic of Dhaka Medical College Hospital over a six-month period. A total of 100 participants were enrolled. Married women, between 30 - 60 years of age with colposcopically diagnosed cervical intra epithelial neoplasia were enrolled. Women with chronic illness, pregnancy, and women unable to consent were excluded from this study. After counselling, colposcopically directed punch biopsies were taken from each CIN case concurrently with high-risk HPV testing by polymerase chain reaction (PCR). Results: The mean age of the patients was 38.69 (SD ±7.76) years. CIN 1 was diagnosed in 57% of participants, while 24% had CIN II and 19% had CIN III lesions. High-risk HPV was present in 52 patients. HPV 16 was the most common identified in 28 (53.84%) and HPV 18 was the second most common with 20 (38.46%) either singly or in combination with other high-risk subtypes. The other HPV strains, HPV 31, 33, 35, 52, 56 and 58, were also detected either as mono or co-infections. Out of the 52 HPV positive cases, 29 (55.8%) had mono infection and 23 (44.2%) had co-infection with several subtypes. The highest incidence (50%) of oncogenic HPV infections was present among women aged 35 - 45 years. Risk factors associated with HPV positive cases were high parity (P 0.05), early age at marriage (P = 0.754) and early age of first child. Conclusion: This study identified a high prevalence of HPV 16 and 18 genotypes. HPV vaccination with the current 9-valent HPV vaccine, which contains HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58. Will be an effective public health measure to eradicate cervical cancer in Bangladesh. 展开更多
关键词 BANGLADESH Cervical Cancer Cervical Intraepithelial neoplasia Human Papillomavirus Infection High-Risk HPV
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SGK3 overexpression correlates with a poor prognosis in endoscopically resected superficial esophageal squamous cell neoplasia:A long-term study
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作者 Ning Xu Long-Song Li +7 位作者 Hui Li Li-Hua Zhang Nan Zhang Peng-Ju Wang Ya-Xuan Cheng Jing-Yuan Xiang En-Qiang Linghu Ning-Li Chai 《World Journal of Gastroenterology》 SCIE CAS 2023年第23期3658-3667,共10页
BACKGROUND The expression status of serum and glucocorticoid-induced protein kinase 3(SGK3)in superficial esophageal squamous cell neoplasia(ESCN)remains unknown.AIM To evaluate the SGK3 overexpression rate in ESCN an... BACKGROUND The expression status of serum and glucocorticoid-induced protein kinase 3(SGK3)in superficial esophageal squamous cell neoplasia(ESCN)remains unknown.AIM To evaluate the SGK3 overexpression rate in ESCN and its influence on the prognosis and outcomes of patients with endoscopic resection.METHODS A total of 92 patients who had undergone endoscopic resection for ESCN with more than 8 years of follow-up were enrolled.Immunohistochemistry was used to evaluate SGK3 expression.RESULTS SGK3 was overexpressed in 55(59.8%)patients with ESCN.SGK3 overexpression showed a significant correlation with death(P=0.031).Overall survival and disease-free survival rates were higher in the normal SGK3 expression group than in the SGK3 overexpression group(P=0.013 and P=0.004,respectively).Cox regression analysis models demonstrated that SGK3 overexpression was an independent predictor of poor prognosis in ESCN patients(hazard ratio 4.729;95% confidence interval:1.042-21.458).CONCLUSION SGK3 overexpression was detected in the majority of patients with endoscopically resected ESCN and was significantly associated with shortened survival.Thus,it might be a new prognostic factor for ESCN. 展开更多
关键词 Superficial esophageal squamous cell neoplasia Serum and glucocorticoid-induced protein kinase Endoscopic submucosal dissection Immunohistochemistry Overall survival
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Q690厚板对接焊残余应力评估及其对焊接接头断裂性能的影响
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作者 王江超 杜仕忠 +4 位作者 牛业兴 张庆亚 赵宏权 吴磊 陈震 《中国舰船研究》 CSCD 北大核心 2024年第4期271-281,共11页
[目的]旨在研究高强钢厚板多层多道焊的复杂焊接残余应力,评估其对焊接接头断裂性能的影响。[方法]以75 mm厚Q690高强钢板为研究对象,制定多层多道对接焊工艺,完成对接接头的焊接,使用轮廓法获得中剖面的纵向残余应力,基于自主开发的高... [目的]旨在研究高强钢厚板多层多道焊的复杂焊接残余应力,评估其对焊接接头断裂性能的影响。[方法]以75 mm厚Q690高强钢板为研究对象,制定多层多道对接焊工艺,完成对接接头的焊接,使用轮廓法获得中剖面的纵向残余应力,基于自主开发的高效热−弹−塑性有限元计算方法,再现厚板多层多道焊的热循环、微观组织演变等现象,将单轴拉伸试验与GTN损伤模型相结合,提出Q690高强钢板的GTN模型参数,分析金属母材及焊接接头试样的断裂特性和应力−应变曲线。[结果]采用所提方法预测的厚板对接接头熔池形状、金相体积分数都与试验测量基本吻合;考虑焊接固态相变和高强钢轧制初始应力的力学分析,得到的焊接残余应力与试验结果高度一致,并得到了横向残余应力分布;考虑焊接微观缺陷及横向残余应力,阐明了残余应力影响焊接接头断裂性能的力学机理。[结论]相关研究可为高强钢厚板焊接结构残余应力及断裂性能评估提供借鉴和指导。 展开更多
关键词 厚板残余应力 接头断裂 轮廓法 gtn模型
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铸态TiZrNbV难熔高熵合金的层裂行为
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作者 陈荣 马荣 +3 位作者 王峥 任柯融 张思源 田占东 《含能材料》 EI CAS CSCD 北大核心 2024年第4期387-396,共10页
为研究高应变率下铸态TiZrNbV难熔高熵合金的层裂行为,获取准确的动态本构参数。采用20 mm一级轻气炮平板撞击实验研究了铸态TiZrNbV难熔高熵合金的层裂特性,对回收试样进行扫描电镜分析,从微观角度获得了铸态TiZrNbV高熵合金在不同应... 为研究高应变率下铸态TiZrNbV难熔高熵合金的层裂行为,获取准确的动态本构参数。采用20 mm一级轻气炮平板撞击实验研究了铸态TiZrNbV难熔高熵合金的层裂特性,对回收试样进行扫描电镜分析,从微观角度获得了铸态TiZrNbV高熵合金在不同应变率下的层裂特性,并基于层裂实验自由面速度历史曲线标定得到了铸态TiZrNbV高熵合金的GTN‑JC本构模型参数。结果表明,TiZrNbV难熔高熵合金的层裂强度随着加载应变率和平台应力的增加而增加,其值为0.93~2.23 GPa;回收试样的几何必要位错密度随着加载速度的提高显著增加。所得参数在模拟铸态TiZrNbV高熵合金层裂行为方面表现良好,模拟结果中自由面速度曲线在第一次拉伸阶段前均较为吻合,可以满足对试样层裂破坏的动态分析,能为铸态TiZrNbV高熵合金的工程应用提供参考。 展开更多
关键词 难熔高熵合金 层裂 参数反演 gtn‑JC 平板撞击
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光动力疗法与子宫颈环形电切术治疗宫颈上皮内瘤变2级的疗效对比
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作者 孙俊杰 郭素杰 +2 位作者 李洪林 岳莹莹 王兴芬 《天津医药》 CAS 2024年第5期509-513,共5页
目的评价光动力疗法与宫颈环形电切术(LEEP)治疗宫颈上皮内瘤变2级(CIN2)的疗效及不良事件的发生情况。方法40例CIN2级患者依治疗方案不同分为光动力组20例和LEEP组20例,于治疗后3、6及12个月进行随访,比较2组患者高危型HPV病毒(HR-HPV... 目的评价光动力疗法与宫颈环形电切术(LEEP)治疗宫颈上皮内瘤变2级(CIN2)的疗效及不良事件的发生情况。方法40例CIN2级患者依治疗方案不同分为光动力组20例和LEEP组20例,于治疗后3、6及12个月进行随访,比较2组患者高危型HPV病毒(HR-HPV)、阴道微生态、阴道镜检查和宫颈活检情况,记录不良事件发生情况。结果2组间患者治疗后3个月的病变逆转、病变残留及病变进展构成差异无统计学意义。光动力组治疗后6个月时1例复发者和LEEP组治疗后12个月时1例复发者的宫颈活检病理均为CIN1级。2组患者治疗后3、6及12个月HR-HPV转阴率、正常阴道微生态比例差异无统计学意义。光动力组治疗后3、6、12个月患者的正常阴道微生态比例呈依次增高的趋势。在治疗过程中,光动力组患者疼痛能忍受,LEEP组疼痛明显并伴有出血;2组治疗后均有阴道分泌物增多、下腹坠痛,但LEEP组有宫颈局部瘢痕形成并有1例出现阴道出血。结论光动力疗法治疗CIN2效果较好,HR-HPV转阴率高,对宫颈几乎无损伤,尤其适用于有生育要求的患者。 展开更多
关键词 宫颈上皮内瘤样病变 光动力疗法 宫颈环形电切术
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乌鲁木齐市11654例女性HPV分型及定量检测结果分析
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作者 师艺 董潇阳 +4 位作者 买为丽旦·衣明江 马文梅 马志萍 庞雪莲 张巍 《检验医学与临床》 CAS 2024年第12期1697-1703,共7页
目的分析新疆乌鲁木齐市女性人乳头瘤病毒(HPV)感染特点及HPV分型定量检测对宫颈病变的预测性能。方法收集2022年1-12月于新疆医科大学第一附属医院妇科就诊并进行HPV检测的11654例女性的HPV检测结果。根据年龄将所有就诊者分为低龄组(... 目的分析新疆乌鲁木齐市女性人乳头瘤病毒(HPV)感染特点及HPV分型定量检测对宫颈病变的预测性能。方法收集2022年1-12月于新疆医科大学第一附属医院妇科就诊并进行HPV检测的11654例女性的HPV检测结果。根据年龄将所有就诊者分为低龄组(≤29岁)、青龄组(>29~39岁)、中龄组(>39~49岁)、中老龄组(>49~59岁)和老龄组(>59岁)。其中1483例患者同时进行阴道镜活检和宫颈组织病理学检测,根据组织病理学诊断结果,将1483例患者分为宫颈炎、宫颈上皮内瘤变(CIN)Ⅰ、CINⅡ、CINⅢ和宫颈癌,将CINⅠ及以上命名为CIN阳性,CINⅡ及以上命名为CINⅡ+,CINⅢ及以上命名为CINⅢ+。采用实时荧光定量PCR检测HPV亚型及病毒载量,比较不同民族、年龄、宫颈疾病女性HPV的检测结果,比较不同宫颈病变患者主要的HPV亚型病毒载量水平,采用受试者工作特征(ROC)曲线确定主要的HPV亚型预测CINⅡ+的病毒载量阈值。结果在11654例就诊者中,HPV感染率为30.60%,单一亚型感染占77.73%。HPV16、52、58是CIN阳性患者感染的主要型别,分别占38.89%、14.90%、11.11%。汉族、维吾尔族、回族和哈萨克族女性HPV感染率分别为31.89%、24.39%、31.76%和27.88%,4个民族HPV感染率比较,差异有统计学意义(χ^(2)=40.929,P<0.001)。在11654例就诊者中,老龄组HPV感染率最高(34.04%),中龄组HPV感染率最低(26.41%),不同年龄组间HPV感染率比较,差异有统计学意义(χ^(2)=37.754,P<0.001)。在396例CIN阳性患者中,高危型HPV和单一亚型感染率随CIN级别升高而升高(χ^(2)趋势=9.994、7.233,P<0.01)。CINⅡ+患者HPV16、52、58病毒载量与宫颈炎患者相比,差异均有统计学意义(P<0.05);且HPV16、52、58病毒载量预测CINⅡ+的最佳截断值分别为4.382、3.694、4.114 copy/104个细胞(经lg转化)。结论新疆乌鲁木齐市女性HPV感染以单一亚型感染为主,HPV16、52、58是主要的感染型别,并且HPV标准化定量具有作为宫颈高级病变预测标志物的潜力。 展开更多
关键词 人乳头瘤病毒 病毒载量 宫颈上皮内瘤变 宫颈癌 新疆
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