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91.
Cameron Talischi Glaucio H. Paulino Chau H. Le 《Structural and Multidisciplinary Optimization》2009,37(6):569-583
Traditionally, standard Lagrangian-type finite elements, such as linear quads and triangles, have been the elements of choice
in the field of topology optimization. However, finite element meshes with these conventional elements exhibit the well-known
“checkerboard” pathology in the iterative solution of topology optimization problems. A feasible alternative to eliminate
such long-standing problem consists of using hexagonal (honeycomb) elements with Wachspress-type shape functions. The features
of the hexagonal mesh include two-node connections (i.e. two elements are either not connected or connected by two nodes),
and three edge-based symmetry lines per element. In contrast, quads can display one-node connections, which can lead to checkerboard;
and only have two edge-based symmetry lines. In addition, Wachspress rational shape functions satisfy the partition of unity
condition and lead to conforming finite element approximations. We explore the Wachspress-type hexagonal elements and present
their implementation using three approaches for topology optimization: element-based, continuous approximation of material
distribution, and minimum length-scale through projection functions. Examples are presented that demonstrate the advantages
of the proposed element in achieving checkerboard-free solutions and avoiding spurious fine-scale patterns from the design
optimization process. 相似文献
92.
孙乐 《数码设计:surface》2009,(12):89-91
在现代平面广告造型元素表现的发展与演变过程中,最不容忽视的就是广告作品由基础阶段的直白表现发展到了婉转传达的更高层次。隐喻广告异军突起,成为有效的传播手段。隐喻广告想走的更远,还需从业人员提升驾驭设计的能力,在造型元素的应用原理理论上做深度研究,在更广泛和更紧密的专业领域汲取营养,并且在广告学理论诉诸隐喻广告设计实践方面做些有效的探索。 相似文献
93.
94.
程乐 《计算机工程与应用》2008,44(34):44-46
通过模拟蟑螂的觅食行为,提出蟑螂算法(Cockroach Swarm Optimization,CSO)。算法充分利用了蟑螂社会的平等特性和群体智慧。食物再分配、回巢等策略的使用使算法具有较强的全局搜索和局部搜索能力。以TSP问题为例对算法进行仿真测试,实验证明算法有效且优于存在的离散粒子群算法(Discrete Particle Swarm Optimization,PSO)。 相似文献
95.
96.
H Adamski J Chevrant-Breton S Odent M Patoux-Pibouin B Le Marec A Laudren M Urvoy 《Canadian Metallurgical Quarterly》1994,121(10):694-699
Oculo-dento-digital syndrome (SODD) as defined by Meyer-Schwickerath in 1957 is a rare entity (84 cases) which belongs to ectodermal dysplasias. It consists of: the characteristic features (long face, pinched nose); syndactyly; ocular, dental and bone abnormalities. This entity is usually transmitted on the autosomal dominant mode. We report two cases (a mother and daughter) with polymalformations which we classed as SODD. Furthermore, agenesis of lacrimal duct and genitourinary abnormalities were noted. The mother had a very particular complex hair shaft dysplasia (incomplete pili torti, "tiger tail" aspect, fractures) with alopecia since she was fifteen years old. The daughter's hair was normal at birth. In SODD, fine and sparse hair is often observed (44 p. 100). Only one patient had hair shaft investigation under polarized light: pili annulati and monilethrix were described but not found in our cases. These two reports incite to the systematic hair shaft study in SODD as other ectodermal dysplasia syndromes. 相似文献
97.
B Le Fourn JY Lebatard-Sartre F Gousset-Lejeune JL Michaud M Pannier 《Canadian Metallurgical Quarterly》1994,39(6):715-724
Thoracic empyema (development of suppuration in the thoracic cavity, usually after pneumonectomy) remains a serious complication which is difficult to treat. Failure of classical procedures (lavage-drainage) in the treatment of certain forms of pleural empyema (post-pulmonary resections), with or without associated fistula, led the authors to use the pedicled omental flaps filling material for the chronic empyema cavity. They report their experience (6 cases over a period of 4 years) and define the indications. Omentoplasty has a real place, next to myoplasty, in the therapeutic arsenal for chronic empyema due to its detersion capacity, particularly useful in a "septic" context and because of its volume which is usually sufficient in retracted cavities. The existence of an associated bronchial fistula, history of radiotherapy, posterolateral thoracostomy (sectioned latissimus dorsi) are additional reasons to prefer omentoplasty over myoplasty. 相似文献
98.
Patrice Le Boudec François Sanchez Pierre-Luc FranÇois Jean-François Bayon Guy Michel StÉphan 《电信纪事》1994,49(3-4):178-192
The dynamics of the erbium doped fiber laser is analysed both experimentally and theoretically. This laser operates spontaneously in self-pulsing, in sinusoidal or in CW regime. Experiments have allowed to determine the control parameters : the cavity losses, the pumping rate and the ion pairs concentration. An antiphase dynamics is observed when the laser operates simultaneously at 1.55 µn and 1.536 µm. The self-pulsing behavior is attributed to a fast energy transfer which occurs between two neighboring ions (pair induced quenching). A simple model considering the active medium as a mixture of isolated ions and ions pairs is developped and leads to a good qualitative agreement with the experimental results. 相似文献
99.
100.
Xiangyu Meng Yuzhao Liu Le Yu Jieshan Qiu Zhiyu Wang 《Advanced functional materials》2023,33(11):2211062
Anode-free batteries can maximize the energy density but their development is hindered by a lack of Li-rich cathodes for compensating the irreversible Li loss. Li2S cathode is particularly appealing to this desire due to 2.6–4.7 folds more Li content and 4.2–6.8 times higher capacity than conventional intercalation cathodes. But its practical application is hindered by poor stability against moisture attacking in the air. Herein, a facile expendable polymer sheathing strategy toward air-stable Li2S cathodes with high capacities for developing high-performance quasi-solid-state anode-free batteries without risk of cell leakage is reported. Tight protection by dense polymer barrier dramatically prolongs the lifetime of Li2S cathode by 2,000 times at least in the air. Such air-stable Li2S cathode allows for high compatibility of anode-free battery production with commercial schemes. More attractively, the polymer protective layer can in situ transform to multifunctional gel polymer electrolyte for releasing ionic pathways and enhancing cell performance by inhibiting LiPS loss and smoothing Li plating. With air-stable Li2S cathode, the quasi-solid-state anode-free cells are assembled in ambient environment to deliver superb volumetric energy density of 1093 Wh L−1. This study may shed new light to push the commercialization of high-energy and reliable anode-free batteries forward. 相似文献