Photobiological hydrogen production from organic materials occurs with the help of illumination and under aerobic conditions within photobioreactors. Novel designs are needed in order to increase the light conversion efficiency and to improve the biological hydrogen production. In this thesis, purple non sulfur bacteria Rhodobacter sphaeroides O.U. 001 was employed as the hydrogen producing microorganism. Two different types of photobioreactors, namely oscillatory helical photobioreactor and recycling helical bioreactor, were devised and successfully operated for bacterial growth and hydrogen production. Total liquid capacity of the pneumatically driven oscillatory flow helical tubular photobioreactor was 11.5 L, and 4.5 L of which was occupied by the bacterial culture. The bacteria grew very well both in malate-based and acetate-based media under nitrogen atmosphere. The bacteria sustained their vitality 24 days before the system was shut down. The recycling helical tubular photobioreactor, which was developed for hydrogen production, had a fully occupied total volume of 6.5L. The bacteria produced approximately 1.9L of hydrogen in four days on malate-based media. The hydrogen production rate was 0.009LH2/Lculture.h. The effects of molecular nitrogen gas and the sodium glutamate concentration on the growth of hydrogen producing photosynthetic bacteria Rhodobacter sphaeroides O.U.001 in the reactor were also examined in 500ml-bottles. The bacterial growth curves did not show any difference at the control medium containing 15mM of acetate and 10 mM of sodium glutamate. However, other bottles containing a lesser amount of N-source was found to grow earlier under the nitrogen atmosphere. Besides, even a 15/2 acetate/sodium glutamate ratio was observed to be sufficient to grow the bacteria for inoculation, and to spend extra sodium glutamate was not necessary. The novel designs developed in this study aim to improve the biological hydrogen production by photosynthetic bacteria, and to provide new ways in adaptation of photobiological systems to outdoor conditions for large-scale applications.

The aim of this study is to combine the basic concepts of mechanics on drill string which are related to directional drilling, thus finding a less complicated and more economical way for drilling directional wells. Slick BHA, which has no stabilizers attached and single stabilizer BHA are analyzed through previously derived formulas gathered from the literature that are rearranged for this study. An actual directional well is redrilled theoretically with a slick BHA and a computer program is assembled for calculating the side force and direction of the well for single stabilizer BHA. Influence of controllable variables on drilling tendency is investigated and reported. The study will be useful for well trajectory and drill string design in accordance with the drilling phase. Also, by using available data from offset wells, drilling engineer can back-calculate the formation anisotropy index (FAI) that is often used for optimizing well trajectories and predicting drilling tendency on new wells in similar drilling conditions. After analysing the directional well data used in this study, it has been concluded that the well could be drilled without a steerable tool if the kick of point (KOP) is not a shallower depth. If the KOP is kept similar, the same curvature could not be achieved without a steerable tool.

In this study it was aimed to design and operate a new system with sufficient number of rotating drums since rotation of turntable is incapable of providing uniformity. Effect of new design on final color values and moisture content were also investigated. Macaroni beads were colored with CoCl2 solution and processed in a domestic microwave oven starting from 11.3&plusmn / 0.10% moisture content and L*= 41.1&plusmn / 0.31 , a*= 8.5&plusmn / 0.27 , b*= 5.3&plusmn / 0.22 color value with turntable and the proposed design. In experiments 40%, 60%, 80% and 100% power levels and 1, 2 and 3 min processing times and 2 different locations were used. The average color values measured were not affected significantly by the locations studied inside the cavity for both operation types. The changes in color values were found to be significant with altering power level for both operation types. Time also changed average color values for samples processed on turntable and in rotating drums. The new design lowered the average L* values of the final product and kept the sample from burning. Average a* and b* values were not significantly affected by the operation type. The uniformity of final product in terms of color distribution was affected significantly by the operation type and the improvement in uniformity calculated quantitatively by means of variances and found out that the new design improved the color uniformity of the final product by 94.7%. The non-uniformity of the products processed on turntable was significantly changed with power level. Time or location did not affect uniformity significantly for both operation types. The final average moisture contents of samples processed on turntable were lower than the ones processed with the new design. That is, the rotating drums lowered the moisture removal compared to the turntable.

Past few decades witnessed the birth and explosive growth of the internet and the communications &ndash / most notably the electronic mail- through it. Studies indicate that although security measures are deployed, their usage is very limited and problematic. This work proposes a system to address some of the shortcomings of present mail security systems, such as underutilization, complicated key management and unwanted immunization against filtering-scanning. A two-layer message encryption scheme with domain level keys is introduced and a performance analysis is presented. An analysis of the improvement on the key management is also presented. Results show that, e-mails can be secured without significant performance impact, and visible ease of key management, by using the system proposed in this thesis.

A two-phase research program was undertaken numerically to assess the behavior of the beam outside of the link that is designed for overstrength of the link in eccentrically braced frames (EBFs). In the first phase, software was developed to conduct a statistical analysis of the typical cases designed according to the AISC Seismic Provisions for Structural Steel Buildings. In this analysis, it was noticed that most of the statistically analyzed cases do not satisfy the code requirement provided for overstrength factor. Furthermore, the analyses results revealed that troublesome designs are highly influenced by normalized link length and slenderness of the beam. In this phase, redistribution of forces between beam and brace after the yielding of beam was also studied and it was observed that the forces not carried by the yielded beam are taken by the brace. In second phase, a total of 91 problematic designs were analyzed on finite element program to investigate the effective parameters on the overstrength issue, and overall and local stability of the beam outside of the links. According to analysis results, it was observed that unbraced beam length and flange slenderness are responsible for the stability of the system. Based on these results, the boundary values were suggested to prevent lateral torsional buckling of the beam and local buckling of the brace connection panel separately. Moreover, the overstrength factor specified by code was found conservative for the intermediate and long links although it is fit for the short links.

The subject of this study is the design of a camera, which has maximum volume of 50 mm x 50 mm x 300 mm, using short infrared wavelength providing Rayleigh criteria. Firstly, the required flux per pixel has been calculated. Throughout these calculations, atmospheric losses have been obtained by MODTRAN program. Also signal to noise ratio has been examined at minimum and maximum integration time intervals. The focal length of the camera has been calculated as it receives 1 m resolution from 8 km distance. Moreover, the lens materials have been used as N-F2, LIF and BaF2 in this six lens system. The design has been done using ZEMAX optical design program and the performance of the system at focal plane was investigated by the help of Seidel aberrations, Modulation transfer Function (MTF), Spot diagram and Optical Path Difference (OPD) fan plot analyses.

This thesis outlines the methodology and experiments associated with the reshaping of human intention via based on the robot movements in Human-Robot Interactions (HRI). Although works on estimating human intentions are quite well known research areas in the literature, reshaping intentions through interactions is a new significant branching in the field of human-robot interaction. In this thesis, we analyze how previously estimated human intentions change based on his/her actions by cooperating with mobile robots in a real human-robot environment. Our approach uses the Observable Operator Models (OOMs) and Hidden Markov Models (HMMs) designed for the intelligent mobile robotic systems, which consists of two levels: the low-level tracks the human while the high-level guides the mobile robots into moves that aim to change intentions of individuals in the environment. In the low level, postures and locations of the human are monitored by applying image processing methods. The high level uses an algorithm which includes learned OOM models or HMM models to estimate human intention and decision making system to reshape the previously estimated human intention. Through this thesis, OOMs are started to be used at the human-robot interaction applications for first time. This two-level system is tested on video frames taken from a real human-robot environment. The results obtained using the proposed approaches are compared according to performance towards the degree of reshaping the detected intentions.

In the analyses of steel framed structures it is customary to assume the beam to column connections as either fully rigid which means that all moments are transferred from beam to column with negligible rotation or ideally pinned that resists negligible moment. This assumption is reasonable for some types of connections. However when considering steel connections such as bolted-bolted double web angle connections it can be seen that the behavior of these connections is in between the two extreme cases. Thus a third connection type, namely semi rigid or partially restrained connection, is introduced. However this type of connection exhibits such a nonlinear behavior that modeling this behavior necessities a substantial effort. Moreover to perform a performance based analyses the true behavior of these connections should be incorporated as part of the modeling effort. Several researches dealing with these two topics have been undertaken in literature. Despite these efforts, modeling of the moment rotation behavior of these connections still requires improvement especially under cyclic loading conditions. In addition to this, performing an analysis with existing elements incorporating semi-rigid connections as a spring attached to beam ends is not practical because of the fact that displacement based formulation increases meshing significantly which requires substantial computational power. In this study a hysteretic (quadra-linear) moment rotation model considering pinching, damage and possibility of residual moment capacity is developed. The behavior is calibrated via experimental data available in the literature. Furthermore a force based macro element considering spread inelastic behavior along the element is presented. With this element several connections located anywhere along the beam could be incorporated in the analysis with less degree of freedom with respect to displacement based elements. Moreover the macro element model can be used in conjunction with corotational formulation for the capture of nonlinear geometric effects.

In this study, perceived comfort and discomfort regarding school busses is assessed with the main focus on students. A total of 149 students and 38 drivers from a private school in Ankara was chosen participated in the study. Two different surveys were conducted on students and drivers separately, in order to assess perceived comfort and discomfort and suitability of the seat design features. Using SPSS Software to analyze the data, factors contributing to safety, driver distraction, perceived discomfort and perceived comfort were investigated. Bus seat comfort is found to be the most influential factor on the general assessment of bus comfort. Although no evidence of significant discomfort related to specific body parts such as neck, shoulders, back, thigh or legs is found, in-depth analysis revealed that seat features such as seat pan cushion firmness or armrest height are in correlation with seat comfort.

ABSTRACT DESIGN AND CONSTRUCTION OF A SIX DEGREE OF PLATFORM G&uuml / rb&uuml / z, Sarper M.S., Department of Mechanical Engineering Supervisor: Prof. Dr. Tuna BALKAN Co-Supervisor: Prof. Dr. M. A. Sahir ARIKAN November 2006, 83 pages In this thesis a six degree of freedom (DOF) parallel manipulator is designed, developed and simulated virtually. The platform, which is specified and focused on in this thesis, is the specific solution for the generating the required data to simulate a land, airborne or sea vehicle&amp / #8217 / s motion trajectory in the laboratory environment. After explaining the need for such platforms for the military industry, the existing devices will be presented and discussed. Then the design period will be explained while pointing out the key performance criteria. The gathered performance values of the first design iteration will be presented and the modifications done in order to get to the expected performance will be given. Finally an investigation, in order to find the maximum payload that the platform can handle, is performed and presented. It is too hard to get to the desired performance values in mechanical design and manufacturing without using the CAD (Computer Aided Design) and CAM (Computer Aided Manufacturing) programs. In this thesis ProEngineer Wildfire&reg / is used for solid modeling the components, the sub-assemblies and the final assembly, ANSYS Workbench&reg / is used for investigating the modal behavior of the components, ADAMS&reg / 2003 is used for the dynamic simulation of the mechanism, ADAMS/Flex&reg / , ADAMS/AutoFlex&reg / and ADAMS/Durability&reg / are used to analyze the results when flexibility is embedded into the system. At the end of the thesis in Appendix section five technical drawings with the nominal dimensions are given in order to clarify the construction period. By the regulations that must be obeyed in ASELSAN only the nominal dimensions are given in the technical drawings. All the dimensional and geometrical tolerances are given in the approved technical drawings that are proprietary of ASELSAN. Keywords: 6-Axis Motion Platform, Application of CAD and analysis programs, Electromechanical Design, Stewart Platform