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621.
As a counterpart to best approximation in normed linear spaces, best coapproximation was introduced by Franchetti and Furi.
In this paper, we shall show that if M is a separable, coproximinal subspace of X satisfying some additional conditions, then L
1 (S, M) is coproximinal in L
1(S, X).
相似文献
622.
623.
624.
In this research, potassium permanganate in the presence of a catalytic amount of [bmim]Br under solvent free conditions is used as an efficient and chemoselective method for oxidative cleavage of some oximes to corresponding carbonyl compounds. This experiment was carried out in mild conditions without any further oxidation of aldehydes to corresponding acids. 相似文献
625.
In this paper a multiple strained layer structure with multiple quantum wells as a piezoelectric transducer is proposed for
generating and detecting nano ultrasound waves with nanometer wavelength and tera hertz frequency. By inducing femtosecond
optical pulses at this strained structure, internal piezoelectric field is changed. As a result longitudinal acoustic phonon
oscillations can be treated as nano acoustic waves. It could be noticed in simulated cases that detection of nano ultrasound
waves can be used in non destructive testing and high accuracy measurements with this structure. It is also shown that the
MQW structure design how influences in generated nano acoustic waves. 相似文献
626.
The stereoscopic molecular tagging velocimetry (SMTV) technique is used to obtain the multiple point measurement of an instantaneous
three-component velocity field inside the cylinder of an internal combustion (IC) engine assembly. A novel image processing
technique is implemented to obtain the velocity data. The technique has the advantage that it eliminates the geometric details
required to obtain the three components of the velocity field. The procedure involves two major steps: (i) calibration process
and (ii) data acquisition and reduction. Cycle-to-cycle variations of the three-component velocity field and out-of-plane
vorticity are presented inside an engine cylinder. Preliminary results show that cycle-to-cycle variations are more prominent
in the velocity component perpendicular to the tumble plane, as opposed to the in-plane components. Such new insights will
help better understand the details of these flows and further improve CFD models for IC engines. 相似文献
627.
Inverse dynamics of a general model of a spherical star-triangle (SST) parallel manipulator (Enferadi and Akbarzadeh Tootoonchi,
Robotica 27:663–676, 2009) is the subject of this paper. This manipulator is of type 3-RRP, has good accuracy and relatively a large workspace which
is free of singularities (Enferadi and Akbarzadeh Tootoonchi, Robotica, Revised paper, 2009). First, inverse kinematics utilizing the angle axis representation is solved. Next, velocity and acceleration analysis as
well as link Jacobian matrices are obtained in invariant form. Finally, a systematic approach based on the principle of virtual
work and the concept of link Jacobian matrices is presented. This method allows elimination of constraint forces and moments
at the passive joints from motion equations. It is shown that the dynamics of the manipulator can be reduced to solving a
system of three linear equations with three unknowns. Moreover, a computational algorithm for solving the inverse dynamics
is developed. Two examples with different trajectories for the moving spherical platform are presented and motor torques are
obtained. Results are verified using a commercial dynamics modeling package. 相似文献
628.
NiAl2O4 spinel nanocrystals were synthesized as mesoporous catalysts and were fully characterized using Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray diffraction patterns (XRD), scanning electron microscopy (SEM), and Energy‐dispersive X‐ray spectroscopy (EDS). These nanocrystals catalyzed the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐one derivatives via a one‐pot, three‐component condensation reaction of aromatic aldehydes, isatoic anhydride, and ammonium acetate or primary aromatic amine under microwave irradiation. By far, the most obvious advantages of the offered process are efficiency and recyclability of the catalyst as well as a significantly shorter reaction time. 相似文献
629.
Azizian J Mohammadi AA Karimi AR Mohammadizadeh MR 《The Journal of organic chemistry》2005,70(1):350-352
KAl(SO(4))(2).12H(2)O is found to catalyze efficiently the stereoselective one-pot three-component cyclocondensation of homophthalic anhydride, aldehydes, and amines under mild conditions to afford the corresponding cis-isoquinolonic acids in good yields. 相似文献
630.
This study reports the development of a production scheduling system for the integrated management of production in large-scale, high-volume electronic assembly lines. The development of the system incorporates control and planning considerations by addressing the interaction of various subsystems. Stochastic and deterministic aspects of the problem environment are appropriately handled via relevant simulation and analytic models. By effecting a hierarchical breakdown of the problem environment, the system produces information used in practical decision making for production planning and scheduling. Procedures used encompass and address considerations for management of work-in-process, optimization of the various subsystems' performance, minimization of setup time effect, and inventory carrying costs. 相似文献