1,305 research outputs found
Microcomputer Aided Selection Of Robot Manipulators
This paper presents two programs for microcomputer aided assessment of the
performance of robot manipulators. The first program automatically generates
robot models based on user-supplied kinematic parameters. The program also
derives a kinematic model that relates the motion of manipulator end-effector to
the motion of the joints using the inverse kinematic approach. The approach uses a
robust inversion technique that can handle singular conditions as well as joint
redundancy. A user can optionally select evaluation of kinematic capabilities of the
robot manipulator, such as the ability of the end-effector to reach a specified
position and orientation in space or the evaluation of the work space. The second
program generates dynamic variables, such as forces and torques, based on
user-supplied dynamic parameters and equations of motion of the various joints.
Both programs are written for implementation on personal computers. Several
runs were carried out to demonstrate the capability and execution times of the two
program
Dynamic Analysis Of A Novel Manpowered Transportation Vehicle With High Mechanical Efficiency
This paper evaluates the dynamics of a novel manpowered
transportation vehicle. The vehicle has a novel mechanism that
maximizes the mechanical input work and utilizes the weight of the
rider for propulsion. The rider applies reciprocating stepping linear
forces to drive chain and ratchet mechanism. The later transfer the
reciprocating motion into a unidirectional rotational motion at the rear
wheel to propel the vehicle. We analyzed the dynamics of the driving
and transmission mechanism and derived the equations of motion, at
first. Then, we evaluated the performance of the vehicle. Results show
significant advantages of the novel driving mechanism
Synthesis of Substituted Thioureas and Their Sulfur Heterocyclic Systems of p
A series of new N,N′-substituted thioureas (2, 6, and 8) and their sulfur heterocycles as thiobarbituric acids (3, 4, and 7), 2-thioxothiazoliodin-4-one (10), thiazolidin-4-one (11), 1,2,4-triazol-5-thione (14), and 1,3,4-thiadiazole (15) of p-Amino salicylic acid (PAS) have been synthesized from treatment with dithiocarbazinate (1, 5 and 12) followed by heterocyclization with dimethyl malonate, chloroacetic acid, and/or trifluoroacetic anhydride. The structures of the newly synthesized compounds were substantiated with IR, H1, and C13 NMR spectral data and elementary microanalyses. The in vitro antitubercular activity of synthesized compounds against M. tuberculosis strain H37Rv showed moderate-to-good activity
Flat Cosmology with Coupled Matter and Dark Energies
Three models of a flat universe of coupled matter and dark energies with
different low-redshift parameterizations of the dark energy equation of state
are considered. The dark energy is assumed to vary with time like the trace of
the energy-momentum tensor of cosmic matter. In the radiation-dominated era the
models reduce to standard cosmology. In the matter-dominated era they are, for
modern values of the cosmological parameters, consistent with data from SNe Ia
searches and with the data of Gurvits et al.(1999)for angular sizes of ultra
compact radio sources. We find that the angular size-redshift tests for our
models offer a higher statistical confidence than that based on SNe Ia data. A
comparison of our results with a recent revised analysis of angular
size-redshift legacy data is made,and the implications of our models with
optimized relativistic beaming in the radio sources is discussed. In particular
we find that relativistic beaming implies a Lorentz factor less than 6,in
agreement with its values for powerful Active Galactic Nuclei.Comment: Version to appear in The Astronomical Journal, with a modified name-
Flat Cosmology with Coupled Matter and Dark Energies. Expanded and Modified
conten
Synthesis and Biological activity of 1,3-Thiazolylidenehydrazinylidene ethylpyridiniumbromide monohydrate, 1,3-Thiazolylidenehydraziniumbromide and 1,3-Thiazolylidenehydrazine derivatives
1,3-Thiazolylidenehydrazinylidene ethylpyridinium bromide monohydrate, 1,3-thiazolylidenehydrazinium bromide and 1,3-thiazolylidenehydrazine derivatives were synthesized by heterocyclization of 2-(1-substituted ethylidene) hydrazinecarbothioamides, characterized and screened for their anti-bacterial activities. The structures of synthesized compounds were established by spectroscopic (IR, 1H, 13C-NMR, Mass) and X-ray analyses
The Burkholderia Cenocepacia OmpA-Like Protein BCAL2958: Identification, Characterization, and Detection of Anti-BCAL2958 Antibodies in Serum from B. Cepacia Complex-Infected Cystic Fibrosis Patients
Respiratory infections by bacteria of the Burkholderia cepacia complex (Bcc) remain an important cause of morbidity and mortality among cystic fibrosis patients, highlighting the need for novel therapeutic strategies. In the present work we have studied the B. cenocepacia protein BCAL2958, a member of the OmpA-like family of proteins, demonstrated as highly immunogenic in other pathogens and capable of eliciting strong host immune responses. The encoding gene was cloned and the protein, produced as a 6× His-tagged derivative, was used to produce polyclonal antibodies. Bioinformatics analyses led to the identification of sequences encoding proteins with a similarity higher than 96 % to BCAL2958 in all the publicly available Bcc genomes. Furthermore, using the antibody it was experimentally demonstrated that this protein is produced by all the 12 analyzed strains from 7 Bcc species. In addition, results are also presented showing the presence of anti-BCAL2958 antibodies in sera from cystic fibrosis patients with a clinical record of respiratory infection by Bcc, and the ability of the purified protein to in vitro stimulate neutrophils. The widespread production of the protein by Bcc members, together with its ability to stimulate the immune system and the detection of circulating antibodies in patients with a documented record of Bcc infection strongly suggest that the protein is a potential candidate for usage in preventive therapies of infections by Bcc
Synthesis of Fluorine Heterocyclic Nitrogen Systems Derived From Sulfa Drugs as PhotochemicalProbe Agents for Inhibition of Vitiligo Disease-Part II
Some more new bioactive fluorine heterocyclic systems containing sulfur and nitrogen as six-membered rings such as; N,Nʼ-disubstituted-thiobarbituric acid, 3-thioxo-1,2,4-triazino[5,6-b]indole, 3-sulfanilamido-1,2,4-triazino[5,6-b]indole and 2-trifluoromethyl-4-imino-6-(sulfamido)1,3,5-triazino [3,2-a]indole derivatives (2-13) have been synthetically derived from the interaction of sulfa drugs with fluorine organic compounds (aldehydes, ketones, anhydride) followed by ring closure reactions. Structures of the targets have been established from their elemental and spectral data. Compounds 3, 6, 10 and 13 could be used as photochemical probe agents in compared with nystatin and nalidixic acid for inhibition of vitiligo diseases
Synthesis of New Fluorine Substituted Heterocyclic Nitrogen Systems Derived from p-Aminosalicylic Acid as Antimycobacterial Agents
Some new fluorine substituted heterocyclic nitrogen systems 2-17 have been synthesized from ring closure reactions of substituted p-amino salicylic acids (PAS). The Schiffs base of PAS was cyclized with chloroacetyl chloride and mercaptoacetic acid to give azetidinone 2, thiazolidinone 3, and spiro-fluoroindolothiazoline-dione 10. However, PAS when reacted directly with 4-fluorobenzoyl chloride and 5-oxazolinone yielded derivatives 4, 5, and 7. Aminomethylation of PAS using formaldehyde and piperidine or piperazine formed N-alkyl and N,N -dialkyl derivatives (11 and 12 respectively) upon fluorinated benzoylation gave compounds 13 and 14. Similarly, treatment of PAS with thiosemicarbazide 15 and subsequent cyclization with diethyl oxalate yielded the fluorinated heterocycle 17. The structures of the fluorinated heterocyclic systems have been established on the basis of elemental analysis, 1 H NMR, 13 C NMR, and MS spectral data. Some of the targets exhibited a high inhibition towards Mycobacterium strain with favorable log P values
Thermodynamics of Decaying Vacuum Cosmologies
The thermodynamic behavior of vacuum decaying cosmologies is investigated
within a manifestly covariant formulation. Such a process corresponds to a
continuous irreversible energy flow from the vacuum component to the created
matter constituents. It is shown that if the specific entropy per particle
remains constant during the process, the equilibrium relations are preserved.
In particular, if the vacuum decays into photons, the energy density and
average number density of photons scale with the temperature as and . The temperature law is determined and a generalized
Planckian type form of the spectrum, which is preserved in the course of the
evolution, is also proposed. Some consequences of these results for decaying
vacuum FRW type cosmologies as well as for models with ``adiabatic'' photon
creation are discussed.Comment: 21 pages, uses LATE
- …