Lunar transit telescope lander design

The Program Development group at NASA's Marshall Space Flight Center has been involved in studying the feasibility of placing a 16 meter telescope on the lunar surface to scan the skies using visible/ Ultraviolet/ Infrared light frequencies. The precursor telescope is now called the TRANSIT LUNAR TELESCOPE (LTT). The Program Development Group at Marshall Space Flight Center has been given the task of developing the basic concepts and providing a feasibility study on building such a telescope. The telescope should be simple with minimum weight and volume to fit into one of the available launch vehicles. The preliminary launch date is set for 2005. A study was done to determine the launch vehicle to be used to deliver the telescope to the lunar surface. The TITAN IV/Centaur system was chosen. The engineering challenge was to design the largest possible telescope to fit into the TITAN IV/Centaur launch system. The telescope will be comprised of the primary, secondary and tertiary mirrors and their supporting system in addition to the lander that will land the telescope on the lunar surface and will also serve as the telescope's base. The lunar lander should be designed integrally with the telescope in order to minimize its weight, thus allowing more weight for the telescope and its support components. The objective of this study were to design a lander that meets all the constraints of the launching system. The basic constraints of the TITAN IV/Centaur system are given

UNSUPERVISED LEARNING FOR ANOMALY DETECTION IN REMOTE SENSING IMAGERY

Landfill fire is a potential hazard of waste mismanagement, and could occur both on and below the surface of active and closed sites. Timely identification of temperature anomalies is critical in monitoring and detecting landfill fires, to issue warnings that can help extinguish fires at early stages. The overarching objective of this research is to demonstrate the applicability and advantages of remote sensing data, coupled with machine learning techniques, to identify landfill thermal states that can lead to fire, in the absence of onsite observations. This dissertation proposed unsupervised learning techniques, notably variational auto-encoders (VAEs), to identify temperature anomalies from aerial landfill imagery. Twenty years of Landsat satellite observations at a number of landfills were examined for hotspots that may be associated with or leading to subsurface fires. The main contribution of this dissertation is to detect temperature anomalies in landfills using the state-of-the-art unsupervised deep learning technique of VAE based on both model reconstruction error and encoder module feature extraction. Additionally, a simple framework for assessing the health state of the landfill at any given time was established by using the clustering findings to generate a past behavior for each location in the landfill and eventually assigning it to one of four risk categories (No Risk, Low Risk, Moderate Risk, and High Risk). This framework can function as a monitoring system, inferring information such as past landfill temperature profiles, predicting possible heat elevation or smoldering events as new observations are added, and identifying the percentage of each of the four risk categories and how they increase or decrease over the lifetime of the landfill

Production of Lunar Concrete Using Molten Sulfur

The United States has made a commitment to go back to the moon to stay in the early part of the next century. In order to achieve this objective it became evident to NASA that a Lunar Outpost will be needed to house scientists and astronauts who will be living on the moon for extended periods of time. A study has been undertaken by the authors and supported by NASA to study the feasibility of using lunar regolith with different binders such as molten sulfur, epoxy or hydraulic cement as a construction material for different lunar structures. The basic premise of this study is that it will be more logical and cost effective to manufacture lunar construction materials utilizing indigenous resources rather than transporting needed materials from earth. Lunar concrete (made from Hydraulic Cement and lunar soil) has been studied and suggested as the construction material of choice for some of the lunar projects. Unfortunately, its hydration requires water which is going to be a precious commodity on the moon. Therefore this study explores the feasibility of using binders other than hydraulic cement such as sulfur or epoxy with lunar regolith as a construction material. This report describes findings of this study which deals specifically with using molten sulfur as a binder for Lunar concrete. It describes laboratory experiments in which the sulfur to lunar soil simulant ratios by weight were varied to study the minimum amount of sulfur required to produce a particular strength. The compressive and tensile strengths of these mixes were evaluated. Metal and fiber glass fibers were added to some of the mixes to study their effects on the compressive and tensile strengths. This report also describes experiments where the sulfur is melted and mixed with the lunar regolith in a specially designed vacuum chamber. The properties of the produced concrete were compared to those of concrete produced under normal pressure

The effect of phonemic segmentation on word recognition through the use of interactive whiteboard among Jordanian English as a foreign language (EFL) beginning readers

Developing effective reading skills is essential among primary learners of English given that this will create many types of awareness, in particular, phonemic awareness. In Jordan, studies have revealed that there is a weak performance in the skill of reading among primary school students and young learner‘s word-reading ability. Studies have also shown that the ability to segment words into phonemes is considered as the most powerful predictor of future reading skill. However, little is known about how phonemic segmentation skill affects word recognition among Jordanian English as a foreign language (EFL) beginning readers using the interactive whiteboard (IWB). This study investigated the effect of phonemic segmentation skill on word recognition among Jordanian EFL beginning readers by using IWB. It also examined their teachers‘ perception towards the use of phonemic segmentation and the use of IWB. The instruments used were word recognition test and cross-sectional questionnaire. The independent sample paired t-test, dependent ttest, descriptive statistics, and one way ANOVA were employed to analyse the data. The pre-tests and post-tests of word recognition were administered to 41 beginning readers in the experimental and control groups. The experimental group received the treatment for four weeks using IWB, whereas the control group was taught using the chalkboard. Meanwhile, the questionnaires were distributed to 86 teachers. The findings showed a significant difference in word recognition test scores between the experimental and control groups. The results also indicated that there was no statistically significant difference in the perceptions of EFL teachers of beginning readers based on gender and teaching experience in relation to the use of phonemic segmentation and IWB. The findings revealed that the EFL teachers provided positive support towards using phonemic segmentation and IWB. The findings propose some pedagogical implications for curriculum designers and English teachers. This includes training Jordanian teachers to integrate phonemic segmentation and IWB in the teaching and learning of reading

Stray inductance effects and protection in GTO thyristor circuits

The recently developed gate turn-off thyristor is now becoming well established as the first choice switching device in high power converters for applications such as uninterruptible power supplies, frequency changers, and AC and some DC variable speed motor drives. The special operating features of these devices in conventional circuit configurations are investigated. The GTO thyristor physical behaviour and operating characteristics are first described and supported by measurements made at turn-off currents of up to 600A on a specially constructed test circuit. From this, it is shown that, owing to the extremely fast rates of fall of anode current at turn-off, voltage overshoot effects caused by the stray circuit inductances are highly dangerous to the device, and effective snubbing is essential. A detailed study of these stray inductance effects in constructed DC chopper and H-bridge inverter circuits follows. The circuits are modelled to include these strays, with appropriate mathematical analysis and computer simulation, to determine which stray inductances are the most influential in causing GTO thyristor voltage stress. The different switching patterns are considered for the H-bridge to provide quasi-square and various pulse width modulated (PWM) output voltage waveforms, and the detailed current transfer paths in the various circuit devices and snubber components defined and mathematically analysed in each case. Practical switching effects of diode reverse recovery and GTO mismatched switching times are demonstrated and possible damaging conditions revealed. All analytical and computed results are supported by experimental measurements. A GTO thyristor will be damaged by attempting to turn-off an over-current, and satisfactory protection against this is essential. Conventional fusing is usually inadequate, and a better method is to use a fast active system utilising either a crowbar and fuse, or rapid direct gate turn-off. Both methods are investigated and experimental results provided. It is concluded that, with appropriate circuit layout and component choice, the unavoidable stray inductance effects can be limited to manageable levels. The most severe effects are caused by the DC source inductance which is the most difficult to minimise. Others within the power circuit, if kept small, will have a marginal effect. Fast over-current protection is achievabl

Variation in the timing of Covid-19 communication across universities in the UK.

During the Covid-19 pandemic, universities in the UK used social media to raise awareness and provide guidance and advice about the disease to students and staff. We explain why some universities used social media to communicate with stakeholders sooner than others. To do so, we identified the date of the first Covid-19 related tweet posted by each university in the country and used survival models to estimate the effect of university-specific characteristics on the timing of these messages. In order to confirm our results, we supplemented our analysis with a study of the introduction of coronavirus-related university webpages. We find that universities with large numbers of students are more likely to use social media and the web to speak about the pandemic sooner than institutions with fewer students. Universities with large financial resources are also more likely to tweet sooner, but they do not introduce Covid-19 webpages faster than other universities. We also find evidence of a strong process of emulation, whereby universities are more likely to post a coronavirus-related tweet or webpage if other universities have already done so

Uranium and Plutonium Recovery by Tributylphosphate Solvation and Trioctylamine Ion association Mechanisms

In this work a flowsheet has been put for the recovery of uranium and plutonium from 2.5M nitric acid solutions using 17.5% tributyl phosphate (TBP) and 2.5% trioctylamine (TOA) in kerosene diluent . The fission products (resulting from irradiated of uranium samples in nuclear research reactor) were removed from the desired actinides U & Pu .The organic phase TBP/TOA/Kerosene, containing both actinides U&Pu were stripped using 0.1 M HNO3. Trioctylamine (2.5 volume ratio ) in mesitylene , has been used in conditions appropriate for the recovery of Pu . From the experiments done using mixer- settler , the concentration of uranium in the organic phase in such conditions was very low ,not exceeding parts of a million

The Impact Assessment Of Demographic Factors On Faculty Commitment In The Kingdom Of Saudi Arabian Universities

Organizational commitment is perceived as an attitude of association to the organization by an employee, which leads to particular job-related behaviors such as work absenteeism, job satisfaction and turnover intensions. Turnover is the ratio of the number of workers that had to be replaced in a given time period to the average number of workers. Employee turnover is affected by job dissatisfaction, errors in employee selection, and poor management. As a performance indicator, turnover should be understood by management and leadership of the company.  Turnover in the teaching profession can have important consequences for universities and students, including the financial and time costs of filling positions, disruption of curricular continuity, and difficulty in maintain a cohesive school environment.  This study examines the impact assessment of personal factors on organizational commitment which leads to turnover intentions. The results indicated that the universities in KSA are not stipulating effective measure to retain their worthy and highly qualified resources. Some of the preventive actions include management training in order to capture warning of job dissatisfaction and periodic workplace evaluation of satisfaction, an open door policy style of management, and uphold strict hiring standards. In order to keep costs down, a streamline and efficient human resource program is suggested. Furthermore, organizations may gain more by attaching employees, increasing their investments, and enhancing their obligations to fulfill their goals

Cladding Modified Fiber Bragg Grating for Copper Ions Detection

This paper reports a fiber Bragg grating (FBG) as a biosensor. The FBGs were etched using a chemical agent,namely,hydrofluoric acid (HF). This implies the removal of some part of the cladding layer. Consequently, the evanescent field propagating out of the core will be closer to the environment and become more sensitive to the change in the surrounding. The proposed FBG sensor was utilized to detect toxic heavy metal ions aqueous medium namely, copper ions (Cu2+). Two FBG sensors were etched with 20 and 40 μm diameters and fabricated. The sensors were studied towards Cu2+ with different concentrations using wavelength shift as a result of the interaction between the evanescent field and copper ions. The FBG sensors showed a good response in terms of significant wavelength shift in corresponding to varying Cu2+ concentrations when immersed in aqueous mediums. The sensors exhibited excellent repeatability towards Cu ions.The results demonstrate that the smaller FBG etching diameter, the better optical response in terms of wavelength and linearity.