Recent Surface Studies Using Biassed Secondary Electron Imaging

The growth and surface diffusion of Cs on Si(100) and Ag on Fe(110) have been studied using biassed secondary electron imaging (b-SEI) and Auger electron spectroscopy (AES). The b-SEI technique was found capable of detecting Cs on the Si surface with a 0.5% ML sensitivity. Unusual diffusion profiles containing linear sections were obtained for coverages (θ) \u3c 1/2 ML. The general form of these profiles were reproduced using a 2-phase model, where Cs chains act as sources of mobile adatoms, in conjunction with a diffusion coefficient of the form D ~ θ (1- Cθ). This form of D, obtained from Boltzmann-Matano analysis, is consistent with diffusion theory including strongly repulsive Cs-Cs interactions. An adatom diffusion energy, Ed, = 0.47 ± 0.05 eV was found to be consistent with measurements of the diffusion coefficient made in the temperature range 333 ≤ T ≤ 363K. The growth mode for Ag on Fe(110) was determined by AES and b-SEI to be Stranski-Krastanov, with islands growing on top of two intermediate layers. Diffusion experiments conducted on finite Ag patches show that following annealing, adatoms dissociate from the islands and second monolayer and contribute to the observed expansion of the first monolayer. The diffusion results also indicate that while islands are still present, there is a competition between adatoms entering and leaving the second monolayer

MICROGRAVITY AND ITS BEARING WITH SPACE FLIGHT-RELATED RESEARCH

This study investigates the unique properties and applications of microgravity in the context of spaceflight research. Understanding and harnessing the behaviors of a microgravity environment opens up the doors to long-term space travel and consequently, future missions to other planets within our solar system. More specifically, simulating and conducting experiments in microgravity environments helps us explore its effects on the various necessary tasks and behaviors that are carried out during spaceflight. The most immediate and pronounced effects of microgravity are on human physiology. In particular, studies have shown that prolonged exposure to microgravity can result in a 20% decrease in muscle mass and a 5% decrease in bone mineral density. As research on these effects continue, astronauts will be better equipped to battle these unusual conditions in order to maintain a healthy and able body during spaceflight. In addition to its effects on the human body, microgravity environments provide promising ways to manufacture materials that would otherwise be too costly or difficult to create on Earth. Manufacturing materials of incredible strength and developing cables that can transmit information at unprecedented speeds are made possible in a microgravity environment. Not only does this paper summarize the currently known effects of microgravity, but it also explores the direct applications of microgravity research in past, present, and future space missions

AN ANALYSIS OF ASTROPHOTOGRAPHY: HOW ACCURATE IS THE PHOTOGRAPHY OF SPACE?

The current research goal is to talk about astrophotography that is designed to interact with non-STEM majors in the natural sciences, and to teach future or beginner astronomers and citizen scientists. The course depends on constructivist tutorial strategies to instruct records, cut price and photo processing strategies, and at the same time address mathematical anxiety. The goal of the pathways is to create an awesome ride in the natural sciences, which has been traditionally linked to imparting pertinent education to a cohort of citizen scientists and novice astronomers - businesses which historically have analyzed an amazing volume of files (both recent and historical archives) and have accomplished countless discoveries. Those enrolled in the route demonstrated a greater grasp of records reduction, photography processing, telescope and digicam use. Most college students had been keen to take up astrophotography as a hobby. Thus, opening the course may lead to creating future citizen scientists and novice astronomers. We found that the strategies required to exercise astrophotography are to create an herbal constructivist involved in instructing our environment. The route can be reproduced somewhere else to train non-science college students with methods in records discount and photo processing, deemed an effective experience to enable them to access STEM fields and appreciate the interconnectedness with astrophotography. It can be considered as a recruiting tool in STEM disciplines

Mars 2020: A Step Closer to the Red Planet

This research paper primarily focuses on the NASA Mars 2020 mission, but will also revisit and discuss past rover missions. As the Mars 2020 mission is ongoing, some information will be updated accordingly. For decades, humans have dreamed of the colonization of Mars for many reasons, such as some similarities shared by Earth and Mars or the close proximity to our planet. In fact, dozens of films, books, and articles have been written, especially in the past 2 decades, about the possibility. As technology advances, we develop newer equipment to hopefully make this possibility into a reality. Of course, placing a moving robotic vehicle on a satellite for research purposes is nothing new and we have done so in the past. However, it is clear that we have come a long way from the first rover we’ve placed on Mars, the Sojourner in 1997. As for the 2020 mission, the main components would include the Perseverance rover and the Ingenuity Mars helicopter. The main objective of the Perseverance is to examine any possible traces of life or the possibility of life - with traces of past microbial life. It would also collect various samples that may prove helpful for future research if brought back to Earth. Compared to the Curiosity rover and its mission, there are many shared similarities, and the Perseverance (and its mission) could be said to be a “continuation” or “extension” of the Curiosity mission. For the Ingenuity, the task is relatively simple - to test the possibility of flight on another planet. Earth’s gravitational pull differs from Mars’, along with many other atmospheric differences, so if the flight of the Ingenuity proves to be successful, it could pave the way for future “travels” on Mars

Core network mobility : active MPLS

This dissertation covers mobility in packet-switched wireless networks and presents a new mechanism based on Multi-Protocol Label Switching (MPLS). The mechanism is named "Active MPLS".The wireless packet-switched networks existing today (WLANs, WiMAX environments, 2.5G and 3G systems) generally offer a number of different packet-based services. When user mobility is supported, a mobile device may be moved between locations without disrupting the running data sessions. Such a movement is called a handover and is implemented by a mobility mechanism. Any mobility mechanism has the task of updating the location of the mobile device during a handover so that the data packets of the running data sessions are always sent to the correct location.Active MPLS is a mobility mechanism that does not only solve this task but that also provides for a scalable and efficient way for packet redirection during a handover. In contrast to many other mobility mechanisms, in Active MPLS packet redirection is achieved without impairing the forwarding of data packets not involved in a handover. The feasibility of Active MPLS is demonstrated through an implementation on real hardware and through simulation. A performance evaluation of Active MPLS in comparison to other mobility approaches completes the dissertation

Core network mobility : active MPLS

This dissertation covers mobility in packet-switched wireless networks and presents a new mechanism based on Multi-Protocol Label Switching (MPLS). The mechanism is named "Active MPLS".The wireless packet-switched networks existing today (WLANs, WiMAX environments, 2.5G and 3G systems) generally offer a number of different packet-based services. When user mobility is supported, a mobile device may be moved between locations without disrupting the running data sessions. Such a movement is called a handover and is implemented by a mobility mechanism. Any mobility mechanism has the task of updating the location of the mobile device during a handover so that the data packets of the running data sessions are always sent to the correct location.Active MPLS is a mobility mechanism that does not only solve this task but that also provides for a scalable and efficient way for packet redirection during a handover. In contrast to many other mobility mechanisms, in Active MPLS packet redirection is achieved without impairing the forwarding of data packets not involved in a handover. The feasibility of Active MPLS is demonstrated through an implementation on real hardware and through simulation. A performance evaluation of Active MPLS in comparison to other mobility approaches completes the dissertation

Link Layer Fragmentation in Packet Based Radio Access networks

3G Radio Access Networks (RANs) generally have to transport traffic with a variety of heterogeneous Quality of Service (QoS) requirements. In today's 3G RANs, Asynchronous Transfer Mode (ATM) technology is used to provide the desired QoS. However, packe