3,894 research outputs found
The physics and kinematics of the evolved, interacting planetary nebula PN G342.0-01.7
Here we aim to study the physical and kinematical characteristics of the
unstudied old planetary nebula (PN) PN G342.0-01.7, which shows evidence of
interaction with its surrounding interstellar medium. We used Integral Field
Spectra from the Wide Field Spectrograph on the ANU 2.3 m telescope to provide
spectroscopy across the whole object covering the spectral range 3400-7000
{\AA}. We formed narrow-band images to investigate the excitation structure.
The spectral analysis shows that the object is a distant Peimbert Type I PN of
low excitation, formally of excitation class of 0.5. The low electron density,
high dynamical age, and low surface brightness of the object confirm that it is
observed fairly late in its evolution. It shows clear evidence for dredge-up of
CN-processed material characteristic of its class. In addition, the low
peculiar velocity of 7 km s shows it to be a member of the young disk
component of our Galaxy. We built a self-consistent photoionisation model for
the PNe matching the observed spectrum, the H luminosity, and the
diameter. On the basis of this we derive an effective temperature and luminosity . The temperature is much
higher than might have been expected using the excitation class, proving that
this can be misleading in classifying evolved PNe. PN G342.0-01.7 is in
interaction with its surrounding interstellar medium through which the object
is moving in the south-west direction. This interaction drives a slow shock
into the outer PN ejecta. A shock model suggests that it only accounts for
about 10\% of the total luminosity, but has an important effect on the global
spectrum of the PN.Comment: 15 pages, 6 figures, A&A accepted 201
A simplified analytical approach for optimal planning of distributed generation in electrical distribution networks
DG-integrated distribution system planning is an imperative issue since the installing of distributed generations (DGs) has many effects on the network operation characteristics, which might cause significant impacts on the system performance. One of the most important characteristics that mostly varies because of the installation of DG units is the power losses. The parameters affecting the value of the power losses are number, location, capacity, and power factor of the DG units. In this paper, a new analytical approach is proposed for optimally installing DGs to minimize power loss in distribution networks. Different parameters of DG are considered and evaluated in order to achieve a high loss reduction in the electrical distribution networks. The algorithm of the proposed approach has been implemented using MATLAB software and has been tested and investigated on 12-bus, 33-bus, and 69-bus IEEE distribution test systems. The results show that the proposed approach can provide an accurate solution via simple algorithm without using exhaustive process of power flow computations
Existence of Solutions for a Class of Quasi-Linear Singular Integro-Differential Equations
2000 Mathematics Subject Classification: 45F15, 45G10, 46B38.An existence theorem is proved for a class of quasi-linear
singular integro-differential equations with Cauchy kernel
Effect of Rosemary and Sweet Marjoram on three Predacious Mites of the Family Phytoseiidae (Acari: Phytoseiidae)
The direct toxicity of two essential oils, Majorana hortensis, Moench and Rosmarinus officinalis L. to adult females of the predacious mites, Amblyseius zaheri Yousef and El-Borolossy, Amblyseius barkeri (Hughes) and Typhlodromus athiasae Porath and Swirski were tested. Rosemary oil was the most toxic to females of A. barkeri and the least to A. zaheri. In contrast,sweet marjoram oil was relatively toxic to T. athiasae and slightly toxic to A. barkeri. Both essential oils,decreased the food consumption rate at the concentration used for A.barkeri and A. zaheri. Females of A. barkeri and A. zaheri suffered a depression in reproduction when treated with 1% of rosemary oil.Both material used seems to be harmless to T. athiasae at 1%
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