scholarly journals Performance measure of satellite flying in coplanar and non-coplanar formation

2018 ◽  
Vol 7 (4.13) ◽  
pp. 66
Author(s):  
Nor Affendy Yahya ◽  
Renuganth Varatharajoo ◽  
A Salahuddin M Harithuddin ◽  
Syaril Azrad

In order to fulfil specific mission objective demand, spacecraft performance can be further optimized by means of various methods or configurations. Like for instance, selection of orbit type and inclination with a periodically repeated ground track will ensure the high efficiency of ground target coverage be accomplished throughout the whole duration of mission. Unfortunately, a single monolithic satellite most often unable to accommodate the requirement solicitated by many multi background users. So, to deal with the issue, an alternative solution would be to operate a swarm of satellites flying in synchronized formation. In this paper, three satellites flying in co-planar and non-coplanar formation were simulated. Here, the resulting model of two deputy satellites operating in the same orbital plane but different phase angle moved along the orbit path while both still maintaining constant relative distance with the non-coplanar chief spacecraft throughout the whole orbit period were presented. The use of unique projected circular orbit (PCO) formation arrangement allows the assessment of some important performance measure parameters like average overlapping coverage area and optimum swath width coverage distance. For the determination of area on the surface of the Earth overlapped by three satellites, the analysis was done using the multiple boundary overlap condition. Parametric studies were conducted involving different formation distance and formation height to observe pattern variation of average total overlapping area and maximum coverage distance. Preliminary result showed that at a specific Earth central angle, the total overlapped area decreased substantially with the increased distance in formation. Height factor does not have significant influence in the total overlapped area variation due to constraint imposed on satellites operating in Low Earth Orbit (LEO) altitude regime. Results were tabulated using 3-dimensional graphs to study the relationships exist between multiple variables. Finally, conclusions were made based on our findings with regards to the performance of positioning satellites in such configuration. 

Plasma ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 82-93
Author(s):  
Bruno Caillier ◽  
Laurent Therese ◽  
Philippe Belenguer ◽  
Philippe Guillot

Mercury discharge lamps are often used because of their high efficiency; however, the usage of mercury lamps will be restricted or forbidden for safety and environmental purposes. Finding alternative solutions to suppress mercury is of major interest. The aim of this work is to increase the luminous efficacy of a commercial-free mercury flat dielectric barrier discharge lamp (Planilum, St Gobain) in order to reach the necessary conditions for the lamp to be used as a daily lighting source. The lamp is made of two glass plates separated by a gap of 2 mm. The gap is filled by a neon xenon mixture. The external electrodes made of transparent ITO (indium tin oxide) are deposited on the lamp glass plates. The electrical signal applied to the electrodes generates a UV-emitting plasma inside the gap. Phosphors deposited on the glass allow the production of visible light. The original electrode geometry is plane-to-plane; this induces filamentary discharges. We show that changing the plane-to-plane geometry to a coplanar geometry allows the plasma to spread all over the electrode surface, and we can reach twice the efficacy of the lamp (32 lm/W) as compared to the original value. Using this new electrode geometrical configuration and changing the electrical signal from sinusoidal to a pulsed signal greatly improves the visual uniformity of the emitted light all over the lamp. Electrical and optical parametric measurements were performed to study the lamp characteristics. We show that it is possible to develop a free mercury lamp with an efficacy compatible with lighting purposes.


2020 ◽  
Vol 8 (25) ◽  
pp. 5547-5548
Author(s):  
Xiao Xiao ◽  
Shasha Zheng ◽  
Xinran Li ◽  
Guangxun Zhang ◽  
Xiaotian Guo ◽  
...  

Correction for ‘Facile synthesis of ultrathin Ni-MOF nanobelts for high-efficiency determination of glucose in human serum’ by Xiao Xiao et al., J. Mater. Chem. B, 2017, 5, 5234–5239, DOI: 10.1039/C7TB00180K.


2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Celosia Lukman ◽  
Christopher Yonathan ◽  
Stella Magdalena ◽  
Diana Elizabeth Waturangi

Abstract Objective This study was conducted to isolate and characterize lytic bacteriophages for pathogenic Escherichia coli from chicken and beef offal, and analyze their capability as biocontrol for several foodborne pathogens. Methods done in this research are bacteriophage isolation, purification, titer determination, application, determination of host range and minimum multiplicity of infection (miMOI), and bacteriophage morphology. Results Six bacteriophages successfully isolated from chicken and beef offal using EPEC and EHEC as host strain. Bacteriophage titers observed between 109 and 1010 PFU mL−1. CS EPEC and BL EHEC bacteriophage showed high efficiency in reduction of EPEC or EHEC contamination in meat about 99.20% and 99.04%. The lowest miMOI was 0.01 showed by CS EPEC bacteriophage. CI EPEC and BL EPEC bacteriophage suspected as Myoviridae family based on its micrograph from Transmission Electron Microscopy (TEM). Refers to their activity, bacteriophages isolated in this study have a great potential to be used as biocontrol against several foodborne pathogens.


Author(s):  
A. K. Malkogianni ◽  
A. Tourlidakis ◽  
A. L. Polyzakis

Geopolitical issues give rise to problems in the smooth and continuous flow of oil and natural gas from the production countries to the consumers’ development countries. In addition, severe environmental issues such as greenhouse gas emissions, eventually guide the consumers to fuels more suitable to the present situation. Alternative fuels such as biogas and coal gas have recently become more attractive because of their benefits, especially for electricity generation. On the other hand, the use of relatively low heating value fuels has a significant effect to the performance parameters of gas turbines. In this paper, the impact of using four fuels with different heating value in the gas turbine performance is simulated. Based on the high efficiency and commercialization criteria, two types of engines are chosen to be simulated: two-shaft simple and single-shaft recuperated cycle gas turbines. The heating values of the four gases investigated, correspond to natural gas and to a series of three gases with gradually lower heating values than that of natural gas. The main conclusions drawn from this design point (DP) and off-design (OD) analysis is that, for a given TET, efficiency increases for both engines when gases with low heating value are used. On the contrary, when power output is kept constant, the use of gases with low heating value will result in a decrease of thermal efficiency. A number of parametric studies are carried out and the effect of operating parameters on performance is assessed. The analysis is performed with customized software, which has been developed for this purpose.


2011 ◽  
Vol 109 ◽  
pp. 400-404
Author(s):  
Yan Hong Yang ◽  
Da Fu Ni

Performance and working principle of high-efficiency multi-cyclone were analyzed, and the structural design shortage of original high-efficiency multi-cyclone was pointed out. Its structure was researched and designed, including determination of setting chamber and pipe number, selection of material and the design of cyclones.


1983 ◽  
Vol 105 (2) ◽  
pp. 206-212 ◽  
Author(s):  
Hua-Ping Li ◽  
F. Ellyin

A plate weakened by an oblique penetration of a circular cylindrical hole has been investigated. The stress concentration around the hole is determined by a finite-element method. The results are compared with experimental data and other analytical works. Parametric studies of effects of angle of inclination, plate thickness, and width are performed. The maximum stress concentration factor (SCF) obtained from the finite-element analysis is higher than experimental results, and this deviation increases with the increase of angle of skewness. The major reason for this difference is attributed to the shear-action between layers parallel to the plate surface which cannot be directly included in the two-dimensional elements. An empirical formula is derived which accounts for the shear-action and renders the finite-element predictions in line with experimentally observed data.


Author(s):  
Shanzhong Duan ◽  
Kurt S. Anderson

Abstract The paper presents a new hybrid parallelizable low order algorithm for modeling the dynamic behavior of multi-rigid-body chain systems. The method is based on cutting certain system interbody joints so that largely independent multibody subchain systems are formed. These subchains interact with one another through associated unknown constraint forces f¯c at the cut joints. The increased parallelism is obtainable through cutting the joints and the explicit determination of associated constraint loads combined with a sequential O(n) procedure. In other words, sequential O(n) procedures are performed to form and solve equations of motion within subchains and parallel strategies are used to form and solve constraint equations between subchains in parallel. The algorithm can easily accommodate the available number of processors while maintaining high efficiency. An O[(n+m)Np+m(1+γ)Np+mγlog2Np](0<γ<1) performance will be achieved with Np processors for a chain system with n degrees of freedom and m constraints due to cutting of interbody joints.


2021 ◽  
pp. 22-27
Author(s):  
Elena Dmitrievna Pserovskaya ◽  
◽  
Anna Pavlovna Grefenshteyn ◽  

For the determination of a potential benefit from creation of a distribution centre the paper proposes a method and presents results of calculation of a decrease of total number of rides and total run of automobiles at various variants of goods consolidation. The authors have established a positive influence of the centre on intracity transportation. At the same time, high efficiency of the considered technology can be reached by involvement of a bigger number of consignees and by consolidation of a relatively small number of goods batches in one automobile at efficient routing and correct selection of location of a distribution centre.


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