A blended education program combines online and classroom learning in a brick-and-mortar setting in order to improve the quality of instruction and provide more engaging student-to-student and student-to-teacher interactions. The blended model reduces tuition costs while boosting student performance levels. This business plan proposes a blended model for Chicago Public Schools (CPS) using the Khan Academy’s online learning platform, and specifically targeting elementary school students at the 4th grade level and above.

Video has been used in educational settings for several years by means of videotapes. However, the use of digital video is not very common in schools and training institutions. Moreover, the literature reports not much about using online video in teacher training purposes. This current study presents an online video-based pre-service teacher training environment, offering online video cases for teacher training purposes. The first purpose is to develop an online video-based training system for teacher training. The online teacher training system includes online video cases on various topics in teacher training. The second aim of this study is to understand what student teachers think about the video cases in the online training environment. The first phase of the study was implemented as a pilot study, and the main study included two cycles of action research. The subjects of the study were students of the Faculty of Education at Middle East Technical University who were enrolled to the CEIT321 - Foundations of Distance Education course. The evaluation of video based training questionnaire was administered to the participants and individual interviews were conducted with a selected group of students according to questionnaire scores. The results of the questionnaire proposed that the students had positive attitudes for the online video cases included in the study. In the interviews, the participants indicated their comments and proposed some improvements regarding the technical aspects and the content of video cases. Participants&#039 / reflections about the video cases and course web server logs also provided parallel findings supporting the interviews and the questionnaire.

Increasing environmental concerns and fuel prices motivate the study of alternative, unconventional aircraft configurations. One such example is the blended-wing-body configuration, which has been shown to have several advantages over the conventional tube-and-wing aircraft configuration. In this thesis, a blended-wing-body aircraft is studied and optimized aerodynamically using a high-fidelity Euler-based flow solver, integrated geometry parameterization and mesh movement, adjoint-based gradient evaluation, and a sequential quadratic programming algorithm. Specifically, the aircraft is optimized at transonic conditions to minimize the sum of induced and wave drag. These optimizations are carried out with both fixed and varying airfoil sections. With varying airfoil sections and increased freedom, up to 52% drag reduction relative to the baseline geometry was achieved: at the target lift coefficient of 0.357, a drag coefficient of 0.01313 and an inviscid lift-to-drag ratio of 27.2 were obtained.

Increasing environmental concerns and fuel prices motivate the study of alternative, unconventional aircraft configurations. One such example is the blended-wing-body configuration, which has been shown to have several advantages over the conventional tube-and-wing aircraft configuration. In this thesis, a blended-wing-body aircraft is studied and optimized aerodynamically using a high-fidelity Euler-based flow solver, integrated geometry parameterization and mesh movement, adjoint-based gradient evaluation, and a sequential quadratic programming algorithm. Specifically, the aircraft is optimized at transonic conditions to minimize the sum of induced and wave drag. These optimizations are carried out with both fixed and varying airfoil sections. With varying airfoil sections and increased freedom, up to 52% drag reduction relative to the baseline geometry was achieved: at the target lift coefficient of 0.357, a drag coefficient of 0.01313 and an inviscid lift-to-drag ratio of 27.2 were obtained.

The blended-wing-body (BWB) configuration appears as a promising contender for the next generation of large transport aircraft. The idea of blending the wing with the fuselage and eliminating the tail is not new, it has long been known that tailless aircraft can suffer from stability and control problems that must be addressed early in the design. This thesis is concerned with identifying and then evaluating the flight dynamics, stability, flight controls and handling qualities of a generic BWB large transport aircraft concept. Longitudinal and lateral-directional static and dynamic stability analysis using aerodynamic data representative of different BWB configurations enabled a better understanding of the BWB aircraft characteristics and identification of the mechanisms that influence its behaviour. The static stability studies revealed that there is limited control power both for the longitudinal and lateral-directional motion. The solution for the longitudinal problem is to limit the static margins to small values around the neutral point, and even to use negative static margins. However, for the directional control problem the solution is to investigate alternative ways of generating directional control power. Additional investigation uncovered dynamic instability due to the low and negative longitudinal and directional static stability. Furthermore, adverse roll and yaw responses were found to aileron inputs. The implementation of a pitch rate command/attitude hold flight control system (FCS) improved the longitudinal basic BWB characteristics to satisfactory levels, or Level 1, flying and handling qualities (FHQ). Although the lateral-directional command and stability FCS also improved the BWB flying and handling qualities it was demonstrated that Level 1 was not achieved for all flight conditions due to limited directional control power. The possibility to use the conventional FHQs criteria and requirements for FCS design and FHQs assessment on BWB configurations was also investigated. Hence, a limited set of simulation trials were undertaken using an augmented BWB configuration. The longitudinal Bandwidth/Phase delay/Gibson dropback criteria, as suggested by the military standards, together with the Generic Control Anticipation Parameter (GCAP) proved possible to use to assess flying and handling qualities of BWB aircraft. For the lateral-directional motion the MIL-F-8785C criteria were used. Although it is possible to assess the FHQ of BWB configuartions using these criteria, more research is recommended specifically on the lateral-directional FHQs criteria and requirements of highly augmented large transport aircraft.

Fly ashes generated from fluidized bed combustion of low calorific value, high ash content Turkish lignites are characterized by high content of acidic oxides, such as SiO2, Al2O3 and Fe2O3, varying in the range 50-70%. However, there exists no study for the investigation of the possibility of using these ashes as concrete admixture. Therefore, in this study, characterization of fly ashes from fluidized bed combustion of a Turkish lignite and evaluation of these fly ashes as a substitute for Portland cement in production of pastes and mortars were carried out. The samples were subjected to chemical, physical, mineralogical and morphological analyses. Results of chemical and physical analyses of three fly ash samples show that they satisfy the requirements of EN 197-1, EN 450 and ASTM C 618, except for CaO and SO3, owing to high content of acidic oxides of these ashes contrary to majority of FBC fly ashes reported in the literature. In addition to characterization studies, water requirement, compressive strength, setting time and soundness tests were also performed for 10%, 20% and 30% fly ash-cement blends and the reference cement. Results of these tests reveal that the blends meet compressive strength, setting time and soundness requirements of ASTM C 595 without any pre-hydration treatment, and that fly ashes from fluidized bed combustion of Turkish lignites have significant potential for utilization as an admixture in manufacture of blended cements.

Numerous agents and mechanisms are known to affect the durability of a concrete structure during its service life. Examples include freezing and thawing, corrosion of reinforcing steel, alkali-aggregate reactions, sulfate attack, carbonation, and leaching by neutral or acidic ground waters. Among these, external sulfate attack was first identified in 1908, and led to the discovery of sulfate resistant Portland cement (SRPC). Besides SRPC, another way of coping with the problem of sulfate attack is the use of pozzolans either as an admixture to concrete or in the form of blended cements This study presents an investigation on the sulfate resistance of blended cements containing different amounts of natural pozzolan and/or low-lime fly ash compared to ordinary Portland cement and sulfate resistant Portland cement. Within the scope of this study, an ordinary Portland cement (OPC) and five different blended cements were produced with different proportions of clinker, natural pozzolan, low-lime fly ash and limestone. For comparison, a sulfate resistant Portland cement (SRPC) with a different clinker was also obtained. For each cement, two different mixtures with the water/cement (w/c) ratios of 0.485 and 0.560 were prepared in order to observe the effect of permeability controlled by water/cement ratio. The performance of cements was observed by exposing the prepared 25x25x285 mm prismatic mortar specimens to 5% Na2SO4 solution for 78 weeks and 50mm cubic specimens for 52 weeks. Relative deterioration of the specimens was determined by length, density and ultrasonic pulse velocity change, and strength examination at different ages. It was concluded that depending on the amount and effectiveness of the mineral additives, blended cements were considered to be effective for moderate or high sulfate environments. Moreover, the cement chemistry and w/c ratio of mortars were the two parameters affecting the performance of mortars against an attack. As a result of this experimental study it was found out that time to failure is decreasing with the increasing w/c ratio and the effect of w/c ratio was more important for low sulfate resistant cements with higher C3A amounts when compared to high sulfate resistant cements with lower C3A amounts.

The extent of the benefits provided by use of SCMs in cementitious systems increases as their percentage amounts in total binder increases. However, the proportion of SCMs in cementitious systems is limited, especially for natural pozzolans, by some factors such as increase in water requirement and decrease in rate of strength development. Therefore investigations are needed to increase the amount of natural pozzolans in blended cements or in concrete as much as possible without decreasing their performance. This aim requires studies on cementitious systems with more reactive natural pozzolans than widely-used ones. The objective of the study was to investigate the pozzolanic activity of natural zeolites (clinoptilolite) from two localities in Turkey, and properties of cementitious systems containing low (15%), moderate (35%) and high (55%) amount of them. The study covers characterization of the natural zeolites used, evaluation of their pozzolanic activity in comparison with some popular mineral admixtures, and properties of pastes, mortars, and concrete mixtures containing low, moderate, and high amounts of natural zeolites. Reactivity of the natural zeolites with Ca(OH)2 was found to be higher than those of the fly ash and the non-zeolitic pozzolan, but lower than that of the silica fume. Natural zeolite blended cements were characterized with the following highlighted properties / faster setting than portland cement, low amounts of Ca(OH)2 and capillary pores larger than 50 nm in hardened pastes, relatively dense microstructure of hardened paste than portland cement, more compatibility with melamine-based superplasticizer than being with naphthalene-based one, and excellent compressive strength performance. Concrete mixtures containing natural zeolites as partial replacement for portland cement were characterized with the following properties / 7-day compressive strength of ~25 MPa and 28-day strength of 45-50 MPa with only 180 kg/m3 portland cement and 220 kg/m3 zeolite dosages (55% replacement), comparable modulus of elasticity with plain portland cement concrete, &ldquo / low&rdquo / and &ldquo / very low&rdquo / chloride-ion penetrability for low and large levels of replacement, respectively.

Online and Blended learning are becoming widespread along with the changing needs of society and advances in technology. Recently, there is a growing emphasis on building learning communities in order to increase the effectiveness of these learning environments. In recent years there is one promising theory that has generated considerable interest and has been widely adopted and studied by researchers: the Community of Inquiry (CoI) framework developed by Garrison, Anderson and Archer (2000). The CoI framework, with its emphasis on critical thinking and collaboration, provides a well-structured model and set of guidelines to create effective learning communities in online and blended learning environments. The purpose of this study was to examine the development of a CoI in online and blended learning contexts in relation to students&amp / #8217 / perceived learning and satisfaction. A graduate course delivered online and blended format was the focus of the study. The data was collected through transcript analysis of online discussion, the CoI Survey, and interviews to examine social, teaching, cognitive presence postings patterns, to explore students&amp / #8217 / perceptions of each presence, learning and satisfaction, and to compare the differences between online and blended learning environments. Overall, all three sources of data indicated that a CoI developed in both courses. However, the study found developmental differences in the CoI presences regarding the course format. In terms of social presence, two categories &amp / #8211 / affective communication and group cohesion &amp / #8211 / were found different. Another difference between the two course formats was on the cognitive presence categories. Overall, the transcript analysis in this study found that integration was the most frequently coded phase in both courses. However, the integration phase was found to be significantly higher in the blended course compared to the online course. Finally, the survey analysis yielded higher perceptions of each presence in both courses. However, the students in the blended course had slightly higher perceptions of each presence. The only significant difference was found on teaching presence. The study also yielded some significant relationships among presences which varied according to the course.

This study analyzed students&rsquo / perceived effectiveness of an online course delivered through one of the open source course content management system, Moodle. Students&rsquo / expectations, perception, comments and suggestions about Moodle were investigated in this study. This is a case study carried out 49 students who attended to CEIT321 Foundation of Distance Education course in summer school in 2008 and 29 students who attended to the same course in fall semester of 2008-2009 academic year at Computer Education and Instructional Technology at Middle East Technical University. Blended learning that combines face-to-face interaction and online learning was used in the course. In this study, the qualitative and quantitative data were gathered from the students attended to the study. The questionnaire was distributed to the participants at the end of the summer school and fall semester. In addition, interviews with the volunteer participants were conducted in order to understand students&rsquo / perceptions, thoughts, expectations, recommendations, and comments on Moodle and its applications. The data showed that students had positive attitudes towards Moodle and its application. This study can contribute the future research studies related with Moodle. Moreover, the results of this study can contribute the development of Moodle.