Approximate closed-form solutions of realistic true proportional navigation guidance using the Adomian decomposition method

Approximate closed-form solutions of the non-linear relative equations of motion of an interceptor pursuing a target under the realistic true proportional navigation (RTPN) guidance law are derived using the Adomian decomposition method in this article. In the literature, no study has been reported on derivation of explicit time-series solutions in closed form of the nonlinear dynamic engagement equations under the RTPN guidance. The Adomian method provides an analytical approximation, requiring no linearization or direct integration of the non-linear terms. The complete derivation of the Adomian polynomials for the analysis of the dynamics of engagement under RTPN guidance is presented for deterministic ideal case, and non-ideal dynamics in the loop that comprises autopilot and actuator dynamics and target manoeuvre, as well as, for a stochastic case. Numerical results illustrate the applicability of the method.

A DC-link Capacitor Voltage Balancing with CMV Elimination using only the Switching State Redundancies for a Reduced Switch Count Multi-Level Inverter fed IM Drive

Common mode voltage (CMV) variations in PWM inverter-fed drives generate unwanted shaft and bearing current resulting in early motor failure. Multilevel inverters reduce this problem to some extent, with higher number of levels. But the complexity of the power circuit increases with an increase in the number of inverter voltage levels. In this paper a five-level inverter structure is proposed for open-end winding induction motor (IM) drives, by cascading only two conventional two-level and three-level inverters, with the elimination of the common mode voltage over the entire modulation range. The DC link power supply requirement is also optimized by means of DC link capacitor voltage balancing, with PWM control., using only inverter switching state redundancies. The proposed power circuit gives a simple power bits structure.

A fast acting detector for abnormal output voltages of an UPS system

A new method of sensing the abnormal output voltage conditions of a single phase UPS system is presented, which provides the information almost instantaneously, so that a fast load transfer can be initiated. A continuous monitoring of the UPS output instantaneous voltage is used so that any under/over voltage, transients, or waveform distortion present can be detected.

The rα structure, chemical shift anisotropy, and the abnormal orientation of methyldichlorophosphine from the NMR spectrum

NMR studies of methyldichlorophosphine have been undertaken in the nematic phase of mixed liquid crystals of opposite diamagnetic anisotropies. The rα structure is derived. The proton chemical-shift anisotropy has been determined from the studies without the use of a reference compound and without a change of experimental conditions. It is shown that the molecule orients in the liquid crystal with positive diamagnetic anisotropy in such a way that the C3 symmetry axis of the CH3P moiety is preferentially aligned perpendicular to the direction of the magnetic field, unlike other similar systems. This is interpreted in terms of the formation of a weak solvent-solute molecular complex. The heteronuclear indirect spin-spin coupling constants are determined. The sign of the two-bond JPH is found to be positive.

Knoevenagel condensation of 2-carbethoxycyclohexanone and malononitrile: Synthesis of 4-cyano-3-ethoxy-1-hydroxy-5,6,7,8-tetrahydroisoquinoline, an isomer of the abnormal product

The structure of the abnormal product 1a formed in the Knoevenagel condensation of 2-carbethoxycyclohexanone and malononitrile has been further confirmed. Oxidation of the tetrahydroisoquinoline 3b using Na2Cr2O-AcOH-H2SO4 gave the keto isoquinoline 3d and the isoquinoline-1-carboxylic acid 5a. The acid chloride of 5a was condensed with diethyl ethoxymagnesiomalonate to afford after decarbethoxylation the methyl ketone 5d which on Baeyer-Villiger oxidation gave a mixture of the acetate 1g and the title compound 1b. The unambiguous synthesis of 1b confirms the structure assigned earlier to the title compound also formed during the partial hydrolysis of the diethoxy compound 1c. Condensation of 2-acetylcyclohexane-1,3-dione with malononitrile gave the quinoline derivative 4c which on ethylation yielded the ketoquinoline 4d. The present studies have confirmed that the quinoline compound 4a is also formed in the condensation of 2-acetylcyclohexanone and cyanoacetamide.

On the elimination of DC in reconstructed wavefronts from in-line holograms

New experimental results to demonstrate that the annoying DC in the reconstructed wavefronts from in-line holograms could be successfully eliminated are presented in this paper. The complete elimination of DC has been achieved by making proper use of a Mach-Zehnder interferometer. The results for an in-line hololens and an in-line Fourier transform hologram are discussed.

N. m. r. and infrared spectroscopic studies of hydrogen bonding in hindered alcohols. An instance of a true hydrogen bonded dimer in an alcohol

Hydrogen bonding in the highly hindered alcohol 2,4-dimethyl-3-ethyl-3-pentanol has been studied by proton n.m.r. and infrared spectroscopy. This alcohol associates to form a dimer but no higher hydrogen bonded species; hence the monomer–dimer equilibrium can be studied without interference from competing processes. Spectral and thermodynamic properties for the hydrogen bonding are reported.

Fracture process zone size and true fracture energy of concrete using acoustic emission

Acoustic emission (AE) energy, instead of amplitude, associated with each of the event is used to estimate the fracture process zone (FPZ) size. A steep increase in the cumulative AE energy of the events with respect to time is correlated with the formation of FPZ. Based on the AE energy released during these events and the locations of the events, FPZ size is obtained. The size-independent fracture energy is computed using the expressions given in the boundary effect model by least squares method since over-determined system of equations are obtained when data from several specimens are used. Instead of least squares method a different method is suggested in which the transition ligament length, measured from the plot of histograms of AE events plotted over the un-cracked ligament, is used directly to obtain size-independent fracture energy. The fracture energy thus calculated seems to be size-independent.

Three-level inverter fed open-end winding IM drive with common mode voltage elimination and reduced power device count

A three-level space phasor generation scheme with common mode elimination and with reduced power device count is proposed for an open end winding induction motor in this paper. The open end winding induction motor is fed by the three-level inverters from both sides. Each two level inverter is formed by cascading two two-level inverters. By sharing the bottom inverter for the two three-level inverters on either side, the power device count is reduced. The switching states with zero common mode voltage variation are selected for PWM switching so that there is no alternating common mode voltage in the pole voltages as well as in phase voltages. Only two isolated DC-links, with half the voltage rating of a conventional three-level neutral point clamped inverter, are needed for the proposed scheme.

Investigation of true remnant polarization response in heterostructured artificial biferroics

Epitaxial bilayered thin films composed of ferromagnetic La0.6Sr0.4MnO3 and ferroelectric 0.7Pb (Mg1/3Nb2/3)O3-0.3(PbTiO3) were fabricated on LaAlO3 (100) substrates by pulsed laser ablation. Ferroelectric, ferromagnetic and magneto-dielectric characterizations performed earlier indicated the possible existence of strain-mediated magneto-electric coupling in these biferroic heterostructures. In order to investigate their true remnant polarization characteristics, usable in devices, room-temperature polarization versus electric field, positive-up negative-down (PUND) pulse polarization studies and remnant hysteresis measurements were carried out. The PUND and remnant hysteresis measurements revealed the significant contribution of the non-remnant component in the observed polarization hysteresis response of these heterostructures. (C) 2010 Published by Elsevier Ltd

Studies in oxasteroids—I : Synthesis of 3-cyano-3-methyl-7-methoxychroman-4-one and the structure of an “abnormal” product

A synthesis of 3-cyano-3-methyl-7-methoxychroman-4-one is reported. The structure of an “abnormal” product obtained during isomerization (III) with potassium t-butoxide in t-butanol, followed by alkylation with methyl iodide has been proved to be 3-t-butoxy-2-cyano- 2-mehthyl-2′,4′-dimethoxypropiophenone (IVa).

Structure of abnormal products isolated from the isomerization of 7-methoxychromano3,4-disoxazole - A novel synthesis of one of the products

A one-step synthesis of (IIb), an isomerization product of 7-methoxychromano3,4-disoxazole, from (III) is reported.

Studies on non-specific interference due to serum in the avidin-biotin microELISA for monkey chorionic gonadotropin and a method for its elimination

A study has been carried out on the non-specific interference due to serum in the avidin biotin micro-ELISA for monkey chorionic gonadotropin. Results suggest that it is not due to any proteolytic activity in the serum, but immunoglobulin or associated factors interfering at the level of antigen-antibody interaction. This interference was eliminated by heating samples at 60°C for 30 min.

Elimination of common mode voltage and fifth and seventh harmonics in a multilevel inverter fed IM drive using 12-sided polygonal voltage spacephasor

A multilevel inverter with 12-sided polygonal voltage space vector structure is proposed in this paper. The present scheme provides elimination of common mode voltage variation and 5(th) and 7(th) order harmonics in the entire operating range of the drive. The proposed multi level structure is achieved by cascading only the conventional two-level inverters with asymmetrical DC link voltages. The bandwidths problems associated with conventional hexagonal voltage space vector structure current controllers, due to the presence of 5(th) and 7(th) harmonics, in the over modulation region, is absent in the present 12-sided structure. So a linear voltage control up to 12-step operation is possible, from the present twelve sided scheme, with less current control complexity. An open-end winding structure is used for the induction motor drive.