Molecular beam epitaxy

Reflection High-Energy Electron Refraction Intensity Oscillations Reflection high-energy electron refraction (RHEED) has been used as a surface probe for in situ observation of monolayer growth using molecular beam epitaxy (MBE) because of its high surface sensitivity and a near grazing incidence. It utilizes diffraction of electrons by surface atoms[1] and the RHEED intensity oscillation can convey morphological information of the growth surface if the intensity oscillation pattern is properly interpreted[2]. The wave properties of electrons make techniques like RHEED feasible. Low-energy electron diffraction (LEED) has also been used to determine the surface structure as well. But RHEED is more preferable to LEED because of its forward…

construction, which reduced the cost (Ward, slides 3 and 5). The design (see Appendix 2, Page 2) was originally created to span across the widest section of river, about 12 in.s. The design optimization process (see Appendix 2, Page 3) revealed that the most optimum distance (traffic score) was 8.422415 in., would cost $137.5625 (see Appendix 2, Page 4), as well as earn a safety and aesthetic score of 0.043432 and 6.878127 respectively. These calculations were used to help redesign the best…

1.0 Introduction A wire is defined as a single, flexible strand or rod of metal which is typically cylindrically-shaped. The core applications of wire, both single- or multi-stranded wire, are to withstand or carry mechanical loads in construction sector, whereas in electrical and electronic field are used to transmit electricity and telecommunications signals. For examples, from view of construction, wires are either braided or fixated together to form a bundle of strands, namely…

On November 7th, 1940, the Tacoma Bridge collapsed into the Tacoma Narrows straight in Washington State. The bridge connected the town of Tacoma and the Kitsap Peninsula, and was one of the first major suspension bridges in the western United States. Unlike other suspension bridges constructed around this time, the Tacoma Bridge failed to withstand wind speeds over 40 miles per hour, due to unequal stress on parts of the bridge. The construction of a suspension bridge must include geometric…

The overall objective of this lab was to verify Bernoulli-Euler beam theory for the lip-loaded cantilever and use that to calculate the Poisson ratio for the material in this case 6061-T6 aluminum. This was done by having to different objectives for each part of the Lab. Part one was use electrical resistance strain gage, this was to measure the strain a cantilever beam as it undergoes a known deflection. We would then compare the measurements with that of the strains predicted by simple beam…

design project was conducted to construct a new wing beam design for the B-52 bomber and to compose an analysis of the new main wing spar. Given the information and the requirements that must be met with this design, our team went through the steps of the design process to come up with 3 concept variants. Of the 3 variants, we recommend to the Air Staff that the beam is to be made out of Steel SAE 4340 and configured into the T-beam shape in order to optimize each requirement for the wing beam…

load is placed onto the material is important as well, based on the tension and bending properties of the given material. Material Stiffness is the Young’s Modulus of a material, therefore the how much loads the material would resist before elastic deformation. For example: For the component stiffness of Timber, the Timber generally has more stiffness when it is placed on the ‘edge on’, since the deflection is smaller, usually of: 3mm at 1KN of load, this may be because this side of the timber…

acting on a material it acts as in equibrilium manner because one push in one direction and another push in opposite direction. The failure of material happens when it disobeys these equibrilium conditions by applying more than force in one direction. Materials under Bending: - The bending force is the force which bends the materials like columns, beams and slabs etc. in which the external loads like columns, beams and slabs etc. applied perpendicular to a longitudinal axis of the material.…

Figure 42. Similar to a beam simple supported, the very first requirement is that the structure bend sufficient to absorb the energy due to the weight, but has to withstand the weight under different loading scenarios. Figure 42: Body loading under a static scenario and its corresponding Shear and Moment diagrams. Utilizing beam simple analysis the Shear and Moment diagrams can be obtained. These diagrams are dependent on the location of the center of gravity (CG) of the subsystems. Those…

Bridges are used around the world to get over a bay of water. There are several different designs that could be used when building bridges such as arc, beam , cable-stayed, truss and suspension bridges. The Golden Gate Bridge is a very well known example of a suspension bridge. It is located in San Francisco, California. Construction began in 1933, in the midst of the Great Depression, and the bridge gave steady jobs to many people during this hard time. It was finished and opened in 1937,…