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排序方式: 共有556条查询结果,搜索用时 15 毫秒
1.
Qingbin Cui Mehmet Emre Bayraktar Makarand Hastak Issam Minkarah 《Canadian Metallurgical Quarterly》2004,20(3):118-125
Since the introduction of warranty provisions in federal highway jobs, more and more state departments of transportation (DOTs) have considered the use of such provisions to protect their initial investment. This paper describes the pros and cons of warranty contracting in highway construction based on a survey of warranty practices in the United States. In particular, the need for state DOTs to buy a warranty for a well-built project is questioned. As an alternative, this paper introduces the warranty option, which gives the DOT the right to buy a warranty only if it becomes necessary at the end of construction. This option is exercised if the performance on site warrants it. This paper describes the mechanics of the warranty option and its advantages over the conventional warranty. A bid evaluation model is also developed for the warranty option approach. 相似文献
2.
Cinkilic Emre Moodispaw Michael Zhang Jianyue Miao Jiashi Luo Alan A. 《Metallurgical and Materials Transactions A》2022,53(8):2861-2873
Metallurgical and Materials Transactions A - The use of secondary aluminum for structural components in the automotive industry is limited by the high Fe contents in recycled alloys which often... 相似文献
3.
Hamed Salimkhani Emre Erdem Selmiye Alkan Gursel Alp Yurum 《Journal of the American Ceramic Society》2021,104(8):4257-4271
Recently, lanthanides have been employed by researchers to examine their impact on the structure and properties of Li7La3Zr2O12 (LLZO) garnets. In this regard, we developed Europium oxide (Eu2O3) doped LLZO (Li7+δEuxLa3−δZr2−δO12−δ) solid electrolyte which demonstrates a cubic phase with the symmetry of Iad (No.230) at room temperature. In this investigation, different concentrations of Eu ranging from 0.1 to 0.6 atoms per formula unit (pfu) were doped into Li7La3Zr2O12 to evaluate the impact of Eu on the stability of the cubic phase and thereby the ionic conductivity. The results unveiled that upon doping Eu3+ ions, the Eu2+ state is also formed and is then self-doped into the structure in which Rietveld refinement coupled with XPS, EPR, and solid-state NMR suggests that Eu3+ ions most probably partially occupy Zr4+ (16a) site, the Eu2+ ions occupy La3+ (24d) site, and the Li+ ions occupy two different sites (24d and 96h). It was further found that such a site preference induces distortion at LaO8 polyhedrons opening up the neck for Li-ions diffusion, thereby enhancing the ionic conductivity. Moreover, it was revealed that Li-ions probably hop from 96h to 24d and then to 96h site to generate the Li-ion movement. Overall, by introducing Eu ions into the LLZO structure, an enhanced bulk ionic conductivity of 0.30 × 10−3 S/cm at 298 K with a minimum electronic conductivity of 2.547 × 10−9 S/cm at 298 K was achieved. 相似文献
4.
For robustness analysis with integral quadratic constraints, we formulate a new positivity condition on the solution of the corresponding linear matrix inequality which is necessary and sufficient for nominal stability of the underlying system. The application of this technical result is illustrated by a complete solution of the L2-gain and robust H2-estimator design problems if the uncertainties are characterized by dynamic integral quadratic constraints. 相似文献
5.
Emrah Öncü Rasit Tutgun Emre Aktas 《International Journal of Satellite Communications and Networking》2023,41(6):589-598
Conventional solid-state power amplifier (SSPA) design approach isolates radio frequency (RF) design from communication theory. In this paper, a unified SSPA design approach is proposed, which optimizes SSPA parameters (bias voltage and input RF signal power) to minimize total DC power consumption while satisfying received SNR constraint specified by the link budget. The effect of SSPA nonlinearity is quantified by the error vector magnitude measured at its output and the corresponding received SNR degradation is analyzed. Using the quantitative metrics for received SNR, it is possible to evaluate highly nonlinear SSPA classes such as Class-B or deep-Class AB, which are normally not considered in conventional SSPA design approach to be used in satellite communication applications. 相似文献
6.
Anwar Syed Muhammad Irmakci Ismail Torigian Drew A. Jambawalikar Sachin Papadakis Georgios Z. Akgun Can Ellermann Jutta Akcakaya Mehmet Bagci Ulas 《Journal of Signal Processing Systems》2022,94(5):497-510
Journal of Signal Processing Systems - Segmentation of thigh tissues (muscle, fat, inter-muscular adipose tissue (IMAT), bone, and bone marrow) from magnetic resonance imaging (MRI) scans is useful... 相似文献
7.
Jun Pan Li Na Quan Yongbiao Zhao Wei Peng Banavoth Murali Smritakshi P. Sarmah Mingjian Yuan Lutfan Sinatra Noktan M. Alyami Jiakai Liu Emre Yassitepe Zhenyu Yang Oleksandr Voznyy Riccardo Comin Mohamed N. Hedhili Omar F. Mohammed Zheng Hong Lu Dong Ha Kim Edward H. Sargent Osman M. Bakr 《Advanced materials (Deerfield Beach, Fla.)》2016,28(39):8718-8725
8.
Peri SR Akgun B Satija SK Jiang H Enlow J Bunning TJ Foster MD 《ACS applied materials & interfaces》2011,3(9):3375-3383
Tailoring the structure of films deposited by plasma-enhanced chemical vapor deposition (PECVD) to specific applications requires a depth-resolved understanding of how the interface structures in such films are impacted by variations in deposition parameters such as feed position and plasma power. Analysis of complementary X-ray and neutron reflectivity (XR, NR) data provide a rich picture of changes in structure with feed position and plasma power, with those changes resolved on the nanoscale. For plasma-polymerized octafluorocyclobutane (PP-OFCB) films, a region of distinct chemical composition and lower cross-link density is found at the substrate interface for the range of processing conditions studied and a surface layer of lower cross-link density also appears when plasma power exceeds 40 W. Varying the distance of the feed from the plasma impacts the degree of cross-linking in the film center, thickness of the surface layer, and thickness of the transition region at the substrate. Deposition at the highest power, 65 W, both enhances cross-linking and creates loose fragments with fluorine content higher than the average. The thickness of the low cross-link density region at the air interface plays an important role in determining the width of the interface built with a layer subsequently deposited atop the first. 相似文献
9.
R. Emre Erkmen 《Computational Mechanics》2013,52(1):65-79
Thin-walled members that have one dimension relatively large in comparison to the cross-sectional dimensions are usually modelled by using beam-type one-dimensional finite elements. Beam-type elements, however, are based on the assumption of rigid cross-section, thus they only allow considerations associated with the beam axis behaviour such as flexural-, torsional- or lateral-buckling and cannot consider the effects of local deformations such as flange local buckling or distortional buckling. In order to capture the local effects of this type shell-type finite element models can be used. Based on the Bridging multi-scale approach, this study proposes a numerical technique that is able to split the global analysis, which is performed by using simple beam-type elements, from the local analysis which is based on more sophisticated shell-type elements. As a result, the proposed multi-scale method allows the usage of shell elements in a local region to incorporate the local deformation effects on the overall behaviour of thin-walled members without necessitating a shell-type model for the whole member. Comparisons with full shell-type analysis are provided in order to illustrate the efficiency of the method developed herein. 相似文献
10.
ABSTRACTWind turbine control is an important task to make the electricity generation secure in terms of energy demand and machine safety. It also yields to control the desired power level and optimized energy because of the assignment of turbine speed. The contactless piezoelectric wind energy harvester (CPWEH) used in this study has three piezoelectric layers located around the shaft with 120 degrees apart and they are buckled by the magnetic force without any physical contact. The superiority of this device is to generate energy for low wind speeds such as 1.5 m/s. However, for high speeds, high total harmonic distortions (THDs) govern the waveforms, thus controlling the turbine speed becomes necessary for optimizing the output power. Encouraged by this, a small low inertia dc generator is coupled with the wind turbine, and the generator terminals are connected to a resistor through a power switch to generate a braking torque that opposes to wind speed direction. By controlling the switch properly, turbine speed is ensured to remain within a certain band, which accordingly prevents the turbine from rotating very fast at damaging wind speeds. Several experiments are performed on the developed CPWEH with/without the presented control scheme which prove the existence of promising performance of our proposal. 相似文献