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131.
Atomic force microscope (AFM) probe with a long and rigid needle tip was fabricated and studied for high Q factor dynamic (tapping mode) AFM imaging of samples submersed in liquid. The extended needle tip over a regular commercially available tapping-mode AFM cantilever was sufficiently long to keep the AFM cantilever from submersed in liquid, which significantly minimized the hydrodynamic damping involved in dynamic AFM imaging of samples in liquid. Dynamic AFM imaging of samples in liquid at an intrinsic Q factor of over 100 and an operational frequency of over 200?kHz was demonstrated. The method has the potential to be extended to acquire viscoelastic material properties and provide truly gentle imaging of soft biological samples in physiological environments. 相似文献
132.
G. Heidari H. Tavakoli S. M. Mousavi Khoie 《Journal of Materials Engineering and Performance》2010,19(8):1183-1188
Composite plating is a method through which the fine particles of metallic or non-metallic compounds are co-deposited in a
plated layer to improve surface properties such as lubrication, wear resistance, and corrosion resistance. In this study,
nano-sized SiC particles were co-deposited with nickel from sulfamat bath using pulsed and direct currents. Scanning electron
microscopy, microhardness, wear, and corrosion tests were carried out to characterize the coating properties. The results
showed that microhardness, wear resistance, and corrosion resistance of Ni-SiC composite coatings increased compared to those
of Ni films. 相似文献
133.
In this article the corrosion rate of the austenitic stainless steel type 304, under the synergistic effect of environmental factors has been assessed via potentiodynamic polarization scan. Salinity, velocity, pH and temperature are the factors which induce effects on the corrosion rate of the considered metal. Quantitative analysis is applied using the full two-level factorial experimental design method, which results in the contribution value of each parameter in changing the quantity of average corrosion rate in both individual and synergistic cases. Besides this quantitative analysis, qualitative analysis has been used to predict the variation direction. These two analyses show the important role of the synergistic action, which changes the variation direction of corrosion rate and the contribution percentage of each parameter in varying the value of corrosion rate. Applying both these analyses can show the magnitude and quality of each parameter’s effect, which is remarkably valuable in marine applications. 相似文献
134.
改进的ASTM G65橡胶轮测试方法可采用220nm二氧化钛颗粒和368μm的砂粒分别在潮湿和干燥条件下使用。在由碳化物粒径不同(传统和亚微米)的两种粉末所制备的WC-CoCr涂层上开展试验,研究碳化物大小和磨损介质特性对涂层磨损性能的影响。采用扫描电镜对同一位置磨损前后的低倍和高倍形貌进行观察,并分析了涂层的磨损机理。结果表明:磨损机理取决于碳化物和磨粒的相对大小。在样品上进行磨损定量分析,通过调整碳化物尺寸可改善磨损性能,测试涂层的一些力学性能用于对比。 相似文献
135.
Thermoeconomic optimization of a multi effect distillation (MED) desalination system with thermo-vapor compressor (TVC) is performed. A model based on the energy and exergy analysis is presented here. An economic model of the system is developed according to the Total Revenue Requirement (TRR) method. The objective functions based on the thermodynamic and thermoeconomic analysis are developed. The proposed multi effect distillation system including six decision variables is considered for optimization. A stochastic/deterministic optimization approach known as genetic algorithm is utilized as an optimization method. This approach is applied to minimize the cost of the system product (fresh water). 相似文献
136.
Hossein ASADI KALAMEH Arash KARAMALI Cosmin ANITESCU Timon RABCZUK 《Frontiers of Structural and Civil Engineering》2012,6(2):101
The modeling of high velocity impact is an important topic in impact engineering. Due to various constraints, experimental data are extremely limited. Therefore, detailed numerical simulation can be considered as a desirable alternative. However, the physical processes involved in the impact are very sophisticated; hence a practical and complete reproduction of the phenomena involves complicated numerical models. In this paper, we present a smoothed particle hydrodynamics (SPH) method to model two-dimensional impact of metal sphere on thin metallic plate. The simulations are applied to different materials (Aluminum, Lead and Steel); however the target and projectile are formed of similar metals. A wide range of velocities (300, 1000, 2000, and 3100 m/s) are considered in this study. The goal is to study the most sensitive input parameters (impact velocity and plate thickness) on the longitudinal extension of the projectile, penetration depth and damage crater. 相似文献
137.
Accelerating oil import dependence in energy consuming nations highlights the importance of having energy supplies at sufficient levels and at stable and reasonable prices. Consequently, it is crucial that oil exporters realize their full production potential. Current debates on energy security are often focused on short-term risks e.g. sudden disruptions due to wars, domestic instability, etc. However, when it comes to assessing oil supplier reliability it is equally important to assess their longer term ability and willingness to deliver oil to the global market. This study analyzes the effects of petroleum investment policies on crude oil production trends in 14 major oil producing countries (2000–2010) by focusing on the political–institutional frameworks that shape the investment conditions for the upstream oil sector. Our findings indicate that countries with less favorable oil sector frameworks systematically performed worse than countries with investor friendly and privatized sectors. The findings indicate that assessments based on remaining reserves and planned production capacities alone could inflate expectations about future oil supplies in a world where remaining crude reserves are located in countries with unfavorable investment frameworks. 相似文献
138.
Fattah-Alhosseini Arash Naseri Majid Alemi Mohamad Hesam 《Metallurgical and Materials Transactions A》2017,48(3):1343-1354
Metallurgical and Materials Transactions A - Effect of B4C/SiC particles content on the microstructure, deformation, and electrochemical behavior of aluminum-based hybrid composite processed by... 相似文献
139.
140.
In this paper we consider the selection and scheduling of several jobs on a single machine with sequence-dependent setup times and strictly enforced time-window constraints on the start times of each job. We demonstrate how to develop network-based algorithms to sustain the desired work in process (WIP) profile in a manufacturing environment. Short-term production targets are used to coordinate decentralised local schedulers and to make the objectives of specific areas in line with the chain objectives. A wide range of test problems with two different network structures are simulated. The effectiveness, efficiency, and robustness of the proposed algorithms are analysed and compared with an exhaustive search approach. 相似文献