Biped robots have gained much attention for decades. A variety of researches has been conducted to make them able to assist or even substitute for humans in performing special tasks. In addition, studying biped robots is important in order to understand the human locomotion and to develop and improve control strategies for prosthetic and orthotic limbs. Some challenges encountered in the design of biped robots are: (1) biped robots have unstable structures due to the passive joint located at the unilateral foot-ground contact. (2) They have different configuration when switching from walking phase to another. During the singlesupport phase, the robot is under-actuated, while turning into an over-actuated system during the double-support phase. (3) Biped robots have many degrees of freedom (DOFs). (4) Biped robots interact with different unknown environments. Therefore, this work attempts to investigate and resolve different issues encountered in dynamics, walking pattern generators and control of biped robots; the details as follows: • Dynamics Two walking patterns have been modeled using two well-known formulations: Lagrangian and the modified recursive Newton-Euler (N-E) formulations. The first walking pattern moves with 6 DOFs during the single support phase (SSP) changing its configuration with 7 DOFs during the double support phase (DSP) (the stance foot will move directly during the DSP). Whereas the other walking pattern has 6 DOFs during all walking phases (the SSP and the two sub-phases of the DSP); the stance foot will be fixed during the first sub-phase of the DSP. These two walking pattern are different in configuration and number of phases during the DSP. To resolve the problem of over-actuation, a linear transition function is proposed to ensure smooth transition for the biped from the SSP to the DSP and vice versa. If we assume ideal dynamic response, this strategy can resolve the discontinuity in input control torque and ground reaction forces. • Walking pattern generators Two methods have been used to generate walking patterns of biped mechanism which are (1) optimal control theory and (2) center of gravity (COG)-based model. Computational optimal control has been performed to investigate the effects of some imposed constraints on biped locomotion, such as enforcing swing foot to move level to the ground, hip motion with constant height etc. finite difference approach has been used to transcribe infinite dimensional optimal control problem into finite dimensional suboptimal control problem. Then parameter optimization has been used to get suboptimal trajectory of the biped with the imposing different constraints. In general, any artificially imposed constraint to biped locomotion can lead to increase in value of input control torques. On the other hand, suboptimal trajectory of biped robot during complete gait cycle had been accomplished with different cases such that continuous dynamic response occurs. Enforcing the biped locomotion to move with linear transition of zero-moment point (ZMP) during the DSP can lead to more energy consumption. Using the simple COG-based model, a comparative study has been conducted to generate continuous motion for COG of the biped; all these methods depend on linear pendulum model. It has been shown all these methods are equivalent. On the other hand, the effect of foot configuration has been investigated. Foot rotation can improve biped configuration at heel strike by controlling foot angle. In addition, foot motion with impact can give some freedom and uniform biped configuration compared with motion without impact. To compensate for the deviation of ZMP trajectory due to approximate model of the COG, a novel strategy has been proposed to satisfy kinematic and dynamic constraints, as well as singularity condition. A stable motion has been obtained for the target walking patterns. • Low-level control Two control schemes have been proposed based on dynamics formulations which are conventional adaptive control based on local approximation technique and Lagrangian formulation, and virtual decomposition control (VDC) based on local approximation technique and recursive N-E formulation. In the first approach (conventional control), a new representation of dynamic matrices has been coined which is computationally efficient than other representation (sparse-base representation, Kronecker product etc.). Controller structures for the SSP and the DSP have been designed in details. Since adaptive control assumes no prior knowledge of estimated weighting matrices; therefore, zero input control torques could be result in at the beginning of each phase. Consequently, discontinuous dynamic response could result. The VDC is an efficient tool for complex robotic system such as biped robot. Therefore each subsystem (link, joint) has been controlled using adaptive approximation–based VDC. A novel optimization technique has been used to deal with continuous dynamic response; however, using zero initial weighting matrices for estimation dynamic matrices and vectors could result in zero input control at beginning of each walking phases.
Dapagliflozin is a novel sodium-glucose cotransporter type 2 inhibitor. This work aims to develop a new
validated sensitive RP-HPLC coupled with a mass detector method for the determination of dapagliflozin, its
alpha isomer, and starting material in the presence of dapagliflozin major degradation products and an internal
standard (empagliflozin). The separation was achieved on BDS Hypersil column (length of 250mm, internal
diameter of 4.6 mm and 5-μm particle size) at a temperature of 35℃. Water and acetonitrile were used as
mobile phase A and B by gradient mode at a flow rate of 1 mL/min. A wavelength of 224nm was selected to
perform detection using a photo diode array detector. The method met the
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The ability of single and mixed bacterial culture to utilize Dora-refineries petroleum wastes was compared. Pseudomonas aeruginosa and Serratia ficaria mixed culture consumed the wastes better than the single bacterial cultures. The highest log. number of viable cells in mixed culture was 6.842 , while in single bacterial cultures it was 6.683 and 5.631, respectively. after 3 days in API medium containing the refinery wastes. The effect of some environmental conditions on the degradation of petroleum wastes was studied included aeration , NaCl concentration , pH and temperature. The growth of bacteria in the agitated culture was higher than stagnant culture the log. of cell no. was 6.021 in the first culture. The h
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Afield experiment was conducted in the college of Agriculture labs Sulaimanya University in 2014 to estimate the genetic variance between 12 genotypes of maize. (SSR) technology was used depending on (PCR) technology. Twenty primers were used for the genetic variance analysis between the studied genotypes and 15 primers showed polymorphic results in repeated experiment caused to experinse 52 alleles which gave 307 bands of range 3.1 by different molecular sizes ranged between 80-1000 pair base the value of PIC reached to phi069 gave high value (0.8785), the range of genetic diversity for studied genotypes reached to (0.625) gave primers pairs phi069 hig value for genetic diversity (0.888). The value of total allele replication ranged at pri
... Show MoreThis Study aimed to studying the effect of Volatile oil extracted from the leaves of Myrtus communis on the growth and activities of the following types of bacteria: Staphylococcus aureus, Streptococcus pyogenes, Klebsilla pneumoniae, Pseudomonas aeruginosa, and the yeast Candida albicans. The results showed an inhibitory effect of the oil on both the growth and activity of the tested microbes. This was reflected by the minimum inhibitory concentration (MIC) of Staphylococcus aureus, Streptococcus pyogenes, Klebsilla pneumoniae, Pseudomonas aeruginosa which was: (2.5, 1.25, and 2.5,5 % respectively), and the yeast (5) %. Also, the Minimum bactericidal concentration (MBC) to the bacteria mentioned above was (5, 2.5,5,10 % respectivel
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« The emergence of satellite channels has led to fundamental changes in the supposed role of television, making it a center of culture and an important tributary to social upbringing and influencing the attitudes and values of individuals and in making public opinion regarding various issues, some television programs target ordinary people at home by virtue of the nature of their subjects, where there is a large audience of viewers, who consume and absorb what is offered to them from the cultural production of those satellite channels that play with the aspirations of groups of society to find metaphysical or magic solutions to their social problems or psychological delusions. The media, through its various messages, contributes to brin
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Silver sulfide and the thin films Ag2Se0.8Te0.2 and Ag2Se0.8S0.2 created by the thermal evaporation process on glass with a thickness of 350 nm were examined for their structural and optical properties. These films were made at a temperature of 300 K. According to the X-ray diffraction investigation, the films are polycrystalline and have an initial orthorhombic phase. Using X-ray diffraction research, the crystallization orientations of Ag2Se and Ag2Se0.8Te0.2 & Ag2Se0.8S0.2 (23.304, 49.91) were discovered (XRD). As (Ag2Se and Ag2Se0.8Te0.2 & Ag2Se0.8S0.2) absorption coefficient fell from (470-774) nm, the optical band gap increased (2.15 & 2 & 2.25eV). For instance, the characteristics of thin films made of Ag2Se0.8Te0.2 and Ag2Se0.8S0.2
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After the year 2003, Iraq went through multiple waves of violence and at different levels on the security, intellectual, political and social levels. Behind that stood several motives and incentives to enable violence that represented the first axis of research, the most important of which was the political motives that circulated an atmosphere that politics against society and transformed power into a field of political brutality against the individual and the group at once. There are also cultural, intellectual, media and economic motives such as weak cultural independence, poverty, marginalization, unemployment and want, and the absence of a media discourse that rejects violence but incites it, on the other ha
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This study includes replication and attenuation of foot and mouth disease virus type O which isolated from infected calves. Many passages for the virus in chick-Embryo were established as a substitute method to the tissue culture which is highly caustic in contrast to the chick embryo. The virus passed ten consequent passages which lead to the reduce of the titer of the virus from 106.53 TCID50/ 0.1 ml in cattle testis tissue culture to 103 TCID50/ 0.1 ml. the pathogenecity of attenuated FMD virus were also studied in both chick-embryo and guinea pigs. Using agar gel diffusion test precipitation antibodies was detected in guinea pig serum after 14 and 21 days post exposure to the attenuated virus. The inoculated guine
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