全文获取类型
收费全文 | 187篇 |
免费 | 4篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 25篇 |
金属工艺 | 4篇 |
机械仪表 | 3篇 |
建筑科学 | 12篇 |
能源动力 | 7篇 |
轻工业 | 13篇 |
石油天然气 | 9篇 |
无线电 | 13篇 |
一般工业技术 | 67篇 |
冶金工业 | 8篇 |
自动化技术 | 28篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 17篇 |
2013年 | 18篇 |
2012年 | 14篇 |
2011年 | 18篇 |
2010年 | 12篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 16篇 |
2006年 | 9篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有191条查询结果,搜索用时 15 毫秒
51.
Kenji Takizawa Matthew Fritze Darren Montes Timothy Spielman Tayfun E. Tezduyar 《Computational Mechanics》2012,50(6):835-854
Fluid?Cstructure interaction (FSI) modeling of parachutes poses a number of computational challenges. These include the lightness of the parachute canopy compared to the air masses involved in the parachute dynamics, in the case of ringsail parachutes the geometric porosity created by the construction of the canopy from ??rings?? and ??sails?? with hundreds of ??ring gaps?? and ??sail slits,?? in the case of parachute clusters the contact between the parachutes, and ??disreefing?? from one stage to another when the parachute is used in multiple stages. The Team for Advanced Flow Simulation and Modeling (T?AFSM) has been successfully addressing these computational challenges with the Stabilized Space?CTime FSI (SSTFSI) technique, which was developed and improved over the years by the T?AFSM and serves as the core numerical technology, and a number of special techniques developed in conjunction with the SSTFSI technique. The quasi-direct and direct coupling techniques developed by the T?AFSM, which are applicable to cases with nonmatching fluid and structure meshes at the interface, yield more robust algorithms for FSI computations where the structure is light. The special technique used in dealing with the geometric complexities of the rings and sails is the homogenized modeling of geometric porosity (HMGP), which was developed and improved in recent years by the T?AFSM. The surface-edge-node contact tracking (SENCT) technique was introduced by the T?AFSM as a contact algorithm where the objective is to prevent the structural surfaces from coming closer than a minimum distance in an FSI computation. The recently-introduced conservative version of the SENCT technique is more robust and is now an essential technology in the parachute cluster computations carried out by the T?AFSM. As an additional computational challenge, the parachute canopy might, by design, have some of its panels and sails removed. In FSI computation of parachutes with such ??modified geometric porosity,?? the flow through the ??windows?? created by the removal of the panels and the wider gaps created by the removal of the sails cannot be accurately modeled with the HMGP and needs to be actually resolved during the FSI computation. In this paper we focus on parachute disreefing, including the disreefing of parachute clusters, and parachutes with modified geometric porosity, including the reefed stages of such parachutes. We describe the additional special techniques we have developed to address the challenges involved and report FSI computations for parachutes and parachute clusters with disreefing and modified geometric porosity. 相似文献
52.
Murat Manguoglu Kenji Takizawa Ahmed H. Sameh Tayfun E. Tezduyar 《Computational Mechanics》2011,48(3):377-384
Iterative solution of large sparse nonsymmetric linear equation systems is one of the numerical challenges in arterial fluid–structure
interaction computations. This is because the fluid mechanics parts of the fluid + structure block of the equation system
that needs to be solved at every nonlinear iteration of each time step corresponds to incompressible flow, the computational
domains include slender parts, and accurate wall shear stress calculations require boundary layer mesh refinement near the
arterial walls. We propose a hybrid parallel sparse algorithm, domain-decomposing parallel solver (DDPS), to address this
challenge. As the test case, we use a fluid mechanics equation system generated by starting with an arterial shape and flow
field coming from an FSI computation and performing two time steps of fluid mechanics computation with a prescribed arterial
shape change, also coming from the FSI computation. We show how the DDPS algorithm performs in solving the equation system
and demonstrate the scalability of the algorithm. 相似文献
53.
Tayfun Nesimoglu 《Circuits, Systems, and Signal Processing》2011,30(4):705-720
The design of frequency-tunable amplifiers is investigated and the trade-off between linearity, efficiency and tunability
is revealed. Several tunable amplifiers using various varactor diode topologies as tunable devices are designed by using load-pull
techniques and their performances are compared. The amplifier using anti-series distortion-free varactor stack topology achieves
38% power added efficiency and it may be tuned from 1.74 to 2.36 GHz (about 35% tunable range). The amplifier using anti-series/anti-parallel
topology is tunable from 1.74 to 2.14 GHz (about 23% tunable range) and provides 42% power added efficiency. It is demonstrated
that tunable amplifiers using distortion-free varactor stack topologies provide better power added efficiency than the tunable
amplifiers using reverse biased varactor diodes and their linearity is similar to that of a conventional amplifier. These
amplifiers may facilitate the realization of frequency agile radio frequency transceiver front-ends and may
replace several parallel connected amplifiers used in conventional multimode radios. 相似文献
54.
Kenji Takizawa Nikolay Kostov Anthony Puntel Bradley Henicke Tayfun E. Tezduyar 《Computational Mechanics》2012,50(6):761-778
We present a detailed computational analysis of bio-inspired flapping-wing aerodynamics of a micro aerial vehicle (MAV). The computational techniques used include the Deforming-Spatial-Domain/Stabilized Space?CTime (DSD/SST) formulation, which serves as the core computational technique. The DSD/SST formulation is a moving-mesh technique, and in the computations reported here we use the space?Ctime version of the residual-based variational multiscale (VMS) method, which is called ??DSD/ SST-VMST.?? The motion and deformation of the wings are based on data extracted from the high-speed, multi-camera video recordings of a locust in a wind tunnel. A set of special space?Ctime techniques are also used in the computations in conjunction with the DSD/SST method. The special techniques are based on using, in the space?Ctime flow computations, NURBS basis functions for the temporal representation of the motion and deformation of the wings and for the mesh moving and remeshing. The computational analysis starts with the computation of the base case, and includes computations with increased temporal and spatial resolutions compared to the base case. In increasing the temporal resolution, we separately test increasing the temporal order, the number of temporal subdivisions, and the frequency of remeshing. In terms of the spatial resolution, we separately test increasing the wing-mesh refinement in the normal and tangential directions and changing the way node connectivities are handled at the wingtips. The computational analysis also includes using different combinations of wing configurations for the MAV and investigating the beneficial and disruptive interactions between the wings and the role of wing camber and twist. 相似文献
55.
Tayfun Bel Shima Mehranpour Atilla Volga Şengül Zeynep Camtakan Nilgun Baydogan 《应用聚合物科学杂志》2021,138(45):51337
Poly (methyl methacrylate) modification by colemanite (CMT) addition has ensured beta shielding improvement. This study has connected with space environmental utilization with Kibo Japanese Experiment Module on International Space Station at low earth orbit. Space environment experiment was performed by using Kibo Experiment Handrail Attachment Mechanism–ExHAM. The changes in beta transmission of the composite were examined (by Sr-90 radioisotope) before and after space environmental utilization and details on beta penetration capacity was examined to protect the equipment (used in aviation and aerospace industries) from space radiation. Beta attenuation variations have indicated composite densification with beta attenuation enhancement after CMT addition. 相似文献
56.
Plasma-activated direct bonding of diamond-on-insulator wafers to thermal oxide grown silicon wafers
Diamond-on-insulator (DOI) wafers featuring ultrananocrystalline diamond are studied via atomic force microscopy, profilometer and wafer bow measurements. Plasma-activated direct bonding of DOI wafers to thermal oxide grown silicon wafers is investigated under vacuum. DOI wafer with chemical mechanical polishing (CMP) on the diamond surface makes a poor bonding to silicon wafers with thermal oxide. Our results show that plasma enhanced chemical vapor deposition of silicon dioxide on top of the DOI wafer, CMP of the oxide layer and annealing are essential to achieve very high quality direct bonding to thermal oxide grown on silicon wafers. Plasma activation results in the formation of high quality bonds without exceeding 550 °C in the direct wafer bonding process. 相似文献
57.
A method that uses statistical techniques to monitor and control product quality is called statistical process control (SPC),
where control charts are test tools frequently used for monitoring the manufacturing process. In this study, statistical quality
control and the fuzzy set theory are aimed to combine. As known, fuzzy sets and fuzzy logic are powerful mathematical tools
for modeling uncertain systems in industry, nature and humanity; and facilitators for common-sense reasoning in decision making
in the absence of complete and precise information. In this basis for a textile firm for monitoring the yarn quality, control
charts proposed by Wang and Raz are constructed according to fuzzy theory by considering the quality in terms of grades of
conformance as opposed to absolute conformance and nonconformance. And then with the same data for textile company, the control
chart based on probability theory is constructed. The results of control charts based on two different approaches are compared.
It’s seen that fuzzy theory performs better than probability theory in monitoring the product quality. 相似文献
58.
Fluid–structure interaction computations based on interface-tracking (moving-mesh) techniques are often hindered if the structural
surfaces come in contact with each other. As the distance between two structural surfaces tends to zero, the fluid mesh in
between distorts severely and eventually becomes invalid. Our objective is to develop a technique for modeling problems where
the contacting structural surfaces would otherwise inhibit flow modeling or even fluid-mesh update. In this paper, we present
our contact tracking technique that detects impending contact and maintains a minimum distance between the contacting structural
surfaces. Our Surface-Edge-Node Contact Tracking (SENCT) technique conducts a topologically hierarchical search to detect
contact between each node and the elements (“surfaces”), edges and other nodes. To keep the contacting surfaces apart by a
small distance, we apply to the contacted nodes penalty forces in SENCT-Force (SENCT-F) and displacement restrictions in SENCT-Displacement
(SENCT-D). By keeping a minimum distance between the contacting surfaces, we are able to update the fluid mesh in between
and model the flow accurately. 相似文献
59.
In this study, rice straw (RS) which was one of the major agricultural residues was used as filler in bio‐based thermoplastic polyurethane (TPU). Several treatments including hot water, alkali, permanganate, peroxide and silane were applied for modifying the surface of RS. The effects of surface modifications on mechanical, flow, morphological, and water absorption properties of green composites were investigated at a constant 30 wt% RS loading. Silane treatment performed after alkaline treatment gave the highest tensile strength, elastic and storage modulus in mechanical tests and gave the lowest water uptake properties. POLYM. COMPOS., 37:1596–1602, 2016. © 2014 Society of Plastics Engineers 相似文献
60.
BACKGROUND: A wide range of 1‐methylcyclopropene (1‐MCP) concentrations as well as various treatment durations have been studied in tomatoes by different researchers. However, little is known about interaction of 1‐MCP doses and maturity stages of tomatoes. Therefore the effects of different concentrations of 1‐MCP on storage and postharvest quality of ‘Zorro’ tomatoes harvested at mature green or pink maturity stages were investigated in a 2‐year trial study. RESULTS: Higher concentrations of 1‐MCP delayed and/or inhibited all parameters related to fruit ripening, such as lycopene, chlorophyll, surface color, polygalacturonase (PG) activity and soluble solids content/titratable acidity (SSC/TA), and these effects were greater in tomatoes harvested at the mature green stages. Lower concentrations of 1‐MCP slightly reduced the loss in general quality features compared with untreated tomatoes. CONCLUSION: The results suggest that 1‐MCP, especially at higher doses, is effective for delaying ripening of mature green tomatoes. Mature green fruits treated with 1000 nL L?1 1‐MCP were stored for 35 days without significant decreases in quality characteristics such as elasticity, surface color and SSC/TA with certain physiological processes (ethylene production, PG activity, lycopene synthesis). Copyright © 2011 Society of Chemical Industry 相似文献