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991.
This work analyzes the problem of residual stress determination in an orthotropic material using the hole drilling technique combined with non-contact, full field optical methods. Due to the complex behavior of the material, first a solution algorithm for the isotropic case is analyzed, then the procedure is extended to solving the more complex problem. In the first part of the work, the simplified Smith–Schajer solution to the through-hole problem for an orthotropic material is analyzed, showing that the same linear least square approach used in the isotropic case applies to a large set of orthotropic materials; based on this analysis a simple residual stress measurement algorithm is developed using either analytical or numerically estimated calibration coefficients.In the second part of the work, the general solution is discussed: since in this case the simplified Smith–Schajer solution cannot be used, the Lekhnitskii’s analysis of the through-hole plate in tension is introduced and extended to handle residual stresses. On this basis a solution algorithm using the nonlinear fit of the theoretical displacement field capable of treating all the orthotropic materials at the cost of a more complex numerical procedure is proposed. The performances of both algorithms are tested against numerically generated noisy fields and experimental ones and show a good reliability and accuracy. 相似文献
992.
接合残余应力对异种接合材料强度的影响很大,正确地分析接合残余应力在界面端附近的分布及其奇异特性,是研究异材强度评价方法的关键问题之一,本文利用弹性学中的Goursat公式和有关微分方程解的理论,求得了平面近似下的界面端附近的残余应力场及其应力奇异性,与单纯的外力作用时的情况不同,残余应力在界面端有可能出现对数型的应力奇异性,并且不能仅用Dunders的异材参数来描述。 相似文献
993.
本文分析了裂尖前,后方塑性区对闭合性能的影响,提出从裂尖塑性钝化量和尾迹区残余塑性变形两个方面来确定裂纹面的残余变形,并讨论了压缩载荷对闭合应力的影响,由此建立了一个疲劳裂纹闭合模型,然后通过模型“有限记忆”性质的假定将它应用到随机加载情况。用此模型对铝合金2219——T851受飞机谱载荷的CCT平面应力试件进行了疲劳寿命估算,估算值与实验结果接近。 相似文献
994.
本文通过溶剂热反应合成了3个异质同晶的配位聚合物[Ni(8-qoac)Cl]n(1,8-Hqoac=喹啉-8-氧醚乙酸),[Fe(8-qoac)Cl]n(2)和[Mn(8-qoac)Cl]n(3)。单晶结构分析表明,这些配合物结晶在Pbca空间群中,其中八面体配位的金属离子首先被2个氯离子桥连形成1个双核结构,双核单元再通过4个反-反配位模式的羧酸根与4个相邻的双核单元连接,形成1个以双核为节点的(4,4)网二维层状结构。磁学表征发现化合物1表现出类自旋倾斜的磁行为,而2和3只表现出简单的反铁磁行为,表明了金属离子的各向异性等特点对磁学行为会产生重要的影响。 相似文献
995.
Nickel(II)–Lanthanide(III) Magnetic Exchange Coupling Influencing Single‐Molecule Magnetic Features in {Ni2Ln2} Complexes 下载免费PDF全文
Naushad Ahmed Chinmoy Das Shefali Vaidya Dr. Stuart K. Langley Prof. Dr. Keith S. Murray Prof. Dr. Maheswaran Shanmugam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14235-14239
Four isostructural [Ni2Ln2(CH3CO2)3(HL)4(H2O)2]3+(Ln3+=Dy ( 1 ), Tb ( 2 ), Ho ( 3 ) or Lu ( 4 )) complexes and a dinuclear [NiGd(HL)2(NO3)3] ( 5 ) complex are reported (where HL=2‐methoxy‐6‐[(E)‐2′‐hydroxymethyl‐phenyliminomethyl]‐phenolate). For compounds 1 – 3 and 5 , the Ni2+ ions are ferromagnetically coupled to the respective lanthanide ions. The ferromagnetic coupling in 1 suppresses the quantum tunnelling of magnetisation (QTM), resulting in a rare zero dc field Ni–Dy single‐molecule magnet, with an anisotropy barrier Ueff of 19 K. 相似文献
996.
James Hoos Nian‐Tzu Suen Svilen Bobev 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(10):945-948
The focus of this paper is on the synthesis and crystal structures of three Zn‐rich compounds with the general formula RE7Zn21+xSi2−x, where RE = Ce [x = 0.95 (1); heptacerium docosazinc silicon], Pr [x = 0.09 (1); heptapraseodymium henicosazinc disilicon], and Nd [x = 0.53 (1); heptaneodymium docosazinc silicon]. The compounds were obtained by high‐temperature reactions, using the respective elements as starting materials. The structures were determined by single‐crystal X‐ray diffraction. The title compounds crystalize in the orthorhombic space group Pbam (No. 55, Pearson symbol oP60) and are isostructural with about a dozen RE7Zn21+xTt2−x (RE = La–Nd; Tt = Ge, Sn, and Pb) compounds previously reported by our group. The results from the present refinements confirm the previously published data on RE7Zn21+xSi2−x (RE = La and Ce; x≃ 1.45) [Malik et al. (2013). Intermetallics, 36 , 118–126]. Additionally, magnetic susceptibility measurements on the corresponding bulk samples show Curie–Weiss paramagnetic behavior from 5 to 300 K, consistent with RE3+ ground states and local‐moment magnetism due to the core 4f electrons. 相似文献
997.
Colin D. Medley Jacob Kay Yi Li Jason Gruenhagen Peter Yehl Nik P. Chetwyn 《Analytica chimica acta》2014
The detection and quantification of residual solvents present in clinical and commercial pharmaceutical products is necessary from both patient safety and regulatory perspectives. Head-space gas chromatography is routinely used for quantitation of residual solvents for small molecule APIs produced through synthetic processes; however residual solvent analysis is generally not needed for protein based pharmaceuticals produced through cultured cell lines where solvents are not introduced. In contrast, antibody drug conjugates and other protein conjugates where a drug or other molecule is covalently bound to a protein typically use solvents such as N,N-dimethylacetamide (DMA), N,N?dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or propylene glycol (PG) to dissolve the hydrophobic small molecule drug for conjugation to the protein. The levels of the solvent remaining following the conjugation step are therefore important to patient safety as these parental drug products are introduced directly into the patients bloodstream. We have developed a rapid sample preparation followed by a gas chromatography separation for the detection and quantification of several solvents typically used in these conjugation reactions. This generic method has been validated and can be easily implemented for use in quality control testing for clinical or commercial bioconjugated products. 相似文献
998.
《中国化学会会志》2017,64(1):73-79
Chemical oxygen demand (COD ) of standard discharge wastewater in offshore oilfields is an important part of oilfield wastewater treatment. Polymer‐containing oily wastewater from oilfields in Bohai Sea was taken as the subject of this study. Combined with wastewater treatment experiments, the major composition of COD such as oils, polymer, and chemical agents is studied. Under certain conditions, the two‐dimensional plug‐flow electrochemical reactor was used to treat wastewater, and a linear relation between COD and concentration was established in the low concentration range. A preliminary study was carried out on the main factors of COD removal, and the results show that, compared to the polymer, oils are more easily electrolyzed whereas the chemical agents are more difficult to be electrolyzed. The highest COD removal by electrochemical treatment of wastewater was 75.34%, and the residual COD in wastewater was mainly contributed by the chemical agents and polymer that were not degraded completely. 相似文献
999.
In this paper we compare the residual lifetime of a used coherent system of age t>0 with the lifetime of the similar coherent system made up of used components of age t. Here ‘similar’ means that the system has the same structure and the component lifetimes have the same dependence (joint reliability copula). Some comparison results are obtained for the likelihood ratio order, failure rate order, reversed failure rate order and the usual stochastic order. Similar results are reported for comparing inactivity time of a coherent system with lifetime of similar coherent system having component lifetimes same as inactivity times of failed components. 相似文献
1000.
运用杂化密度泛函理论方法在(U)B3LYP/LanL2DZ水平研究了RuSin(n=1~6)团簇体系的稳定结构及电子性质.结果发现:RuSin(n=1~6)团簇基本保持了纯硅团簇的框架.对原子平均束缚能和分裂能的计算表明,RuSi6团簇是RuSin(n=1~6)团簇中热力学稳定性最强的.对自然电荷分布的研究结果发现,RuSin(n=2,4~6)团簇的最低能结构出现电荷反转现象. HOMO-LUMO能隙的研究结果表明掺入钌原子后团簇的化学活性增强了,且RuSi的化学活性是RuSin(n=1~6)团簇最强的。通过对团簇磁矩的研究发现,RuSi和RuSi3团簇具有了磁性,其余团簇的总磁矩为零,且RuSin(n=1~6)团簇中各原子对团簇总磁矩的贡献不同. 相似文献