Suchergebnisse

In this study, the first kind Bessel function was used to solve Kepler equation for an elliptical orbiting satellite. It is a classical method that gives a direct solution for calculation of the eccentric anomaly. It was solved for one period from (M=0-360)° with an eccentricity of (e=0-1) and the number of terms from (N=1-10). Also, the error in the representation of the first kind Bessel function was calculated. The results indicated that for eccentricity of (0.1-0.4) and (N = 1-10), the values of eccentric anomaly gave a good result as compared with the exact solution. Besides, the obtained eccentric anomaly values were unaffected by increasing the number of terms (N = 6-10) for eccentricities (0.8 and 0.9). The Bessel function's solution appeared to be close to the exact solution for eccentricity of 1 and more than 10 number of terms. Finally, the representation of the first kind Bessel function J1(x) was closer to the exact representation only for eccentricity 0.5 and (N=1-10).

In this research, the eccentricity will be calculated as well as the best height of satellite orbit that can used to transfer from that orbit around the Earth to construct an interplanetary trajectory, for example Mars, when the transfer can be accomplished by a simple impulse, that means the transfer consists of an elliptical orbit from the inner orbit (at a perigee point) to the outer orbit (at apogee point). We will determine Keplerian equation to find the value of a mean anomaly(M) by Rung-Cutta method.
There are several types of satellites orbits around the Earth, but by this study, we find that the best stable orbit to the satellite that is used to inter its orbit around Mars is the Medium Earth Orbit (MEO) at a height about 3500km above the Earth surface. (MEO) comprises a wide range of orbits anywhere between LEO and GEO, its height above the Earth surface is about 2000-35700 km, and it is very commonly used by navigation satellites.
The values ​​of Euler angles (i=23.45°, Ω=20°, w=60°) were installed and the values ​​of each of the height of the perigee point were changed by controlling the height from the ground surface (hp=500, 3500, 35800) km and the eccentricity of the orbit from e=0.1 to 0.9. We found that the best stable orbit of the satellite around the Earth in preparation for its transition to another orbit around Mars is at an altitude of 3500 km, with eccentricity of approximately 0.6, because this orbit was the most stable according to the program results shown in the graphs (no.10) because at the perigee of the orbit we obtained the highest escape speed was approximately 8 km/sec, which means the possibility of transfer with the lowest possible energy.

The perturbed equation of motion can be solved by using many numerical methods. Most of these solutions were inaccurate; the fourth order Adams-Bashforth method is a good numerical integration method, which was used in this research to study the variation of orbital elements under atmospheric drag influence. A satellite in a Low Earth Orbit (LEO), with altitude form perigee = 200 km, was selected during 1300 revolutions (84.23 days) and ASat / MSat value of 5.1 m2/ 900 kg. The equations of converting state vectors into orbital elements were applied. Also, various orbital elements were evaluated and analyzed. The results showed that, for the semi-major axis, eccentricity and inclination have a secular falling discrepancy, Longitude of Ascending Node is periodic, Argument of Perigee has a secular increasing variation, while true anomaly grows linearly from 0 to 360°. Furthermore, all orbital elements, excluding Longitude of Ascending Node, Argument of Perigee, and true anomaly, were more affected by drag than other orbital elements, through their falling as the time passes. The results illustrate a high correlation as compared with literature reviews in this field.

An evaluation was achieved by designing a matlab program to solve Kepler's equation of an elliptical orbit for methods (Newton-Raphson, Danby, Halley and Mikkola). This involves calculating the Eccentric anomaly (E) from mean anomaly (M=0°-360°) for each step and for different values of eccentricities (e=0.1, 0.3, 0.5, 0.7 and 0.9). The results of E were demonstrated that Newton's- Raphson Danby's, Halley's can be used for e between (0-1). Mikkola's method can be used for e between (0-0.6).The term that added to Danby's method to obtain the solution of Kepler's equation is not influence too much on the value of E. The most appropriate initial Gauss value was also determined to be (En=M), this initial value gave a good result for (E) for these methods regardless the value of e to increasing the accuracy of E. After that the orbital elements converting into state vectors within one orbital period within time 50 second, the results demonstrated that all these four methods can be used in semi-circular orbit, but in case of elliptical orbit Danby's and Halley's method use only for e ≤ 0.7, Mikkola's method for e ≤ 0.01 while Newton-Raphson uses for e < 1, which considers more applicable than others to use in semi-circular and elliptical orbit. The results gave a good agreement as compared with the state vectors of Cartosat-2B satellite that available on Two Line Element (TLE).

To transfer a satellite or a spacecraft from a low parking orbit to a geosynchronous orbit, one of the many transition methods is used. All these methods need to identify some orbital elements of the initial and final orbits as perigee and apogee distances. These methods compete to achieve the transition with minimal consumption of energy, transfer time and mass ratio consumed ), as well as highest accuracy of transition. The ten methods of transition used in this project required designing programs to perform the calculations and comparisons among them.
The results showed that the evaluation must depend on the initial conditions of the initial orbit and the satellite mechanical exception as well as the target orbit. The most efficient methods of transition in terms of energy required were, sequentially, methods 10, 1, 8, 9, and 2, whereas the least efficient in terms of energy consumption, fuel and transition time were, sequentially, methods 5,6, and 7. Method 3 was the most efficient when the orbit needed to change the inclination with the transition. The first phase of multi-stage transition is the most energy consuming.

Not Available ; Yaks (971) from 8 farms were systematically sampled. The study showed the overall infection rate of 18.43% in yaks, either in single (9.43%) or mixed infection (14.83%) with mean eggs per gram of faeces (EPG) of 43.862. The incidence was significantly lower in Government yak farm (16.7%) than that of privately managed farms (18.51%). The highest prevalence (23.53%) was noticed in private yak farm at Yumthang, North Sikkim. Strongyles, Strongyloides, Nematodirous and Ascaroid spp. were the most prevalent parasites. Higher rate of gastrointestinal parasitic infections was also found in animals at Kupup village (22.22%) than in yaks reared at Gnathang valley in East Sikkim, and a greater proportion of study animals had moderate EPG (10.81%). Age and sex were significant variables for the development of gastrointestinal parasites; 15.37% of animals over 24 months of age and 19.8% of females were found infected. The seasonal distribution of gastrointestinal parasitism indicated a higher percentage of infection during summer (24.31%) followed by autumn (19.92%) and spring (18.27%). The infection rate was significantly lower in winter (11.87%). The present results may be useful to formulate an appropriate management strategy for gastrointestinal parasites of yaks in Sikkim. Gastrointestinal parasitic infections in yaks at different farms of humid North-East Himalayan region of Sikkim, India | Request PDF. Available from: https://www.researchgate.net/publication/283757307_Gastrointestinal_parasitic_infections_in_yaks_at_different_farms_of_humid_North-East_Himalayan_region_of_Sikkim_India [accessed Sep 27 2018]. ; Not Available

Not Available ; In sheep, brucellosis is mainly caused by Brucella melitensis which is an important reproductive disease and is characterized by abortion in the fourth or fifth month of gestation, stillbirths and reproductive failure. The Rev.1 live B. melitensis vaccine is the most widely used vaccine in control programs against brucellosis in small ruminants in different parts of the world. This vaccine however shows a considerable degree of virulence and induces abortions. In India, B. melitensis Rev.1 vaccine for small ruminants is officially not recommended by the Government of India. Present study reports B. melitensis Rev.1 vaccinal antibodies detection in breeding sheep flock due to use of Brucella melitensis Rev1 vaccine. We investigated an organized sheep flock located in the southern part of India, consisting around 1200 sheep of breeds like Rambouillet and Bannur local breed ewes (600), Rambouillet lamb (300), crossbreds of Rambouillet and Dorper (200) and Rams (100) by random sampling of forty six sheep (vaccinated-20 and unvaccinated-26) in order to detect antibodies against B. melitensis Rev-1 vaccinal strain. Among 20 vaccinated sheep serum samples tested, 19 (95%) and 13 (65%) and 19 (95%) were positive for anti Brucella antibodies by RBPT, SAT and iELISA respectively which is a major drawback of Rev-1 vaccine. This study further emphasized the need to initiate the control strategy in terms of suitable vaccines against B. melitensis in India in order to prevent import of Rev-1 vaccine by the farmers. ; Not Available

Not Available ; In sheep, brucellosis is mainly caused by Brucella melitensis which is an important reproductive disease and is characterized by abortion in the fourth or fifth month of gestation, stillbirths and reproductive failure. The Rev.1 live B. melitensis vaccine is the most widely used vaccine in control programs against brucellosis in small ruminants in different parts of the world. This vaccine however shows a considerable degree of virulence and induces abortions. In India, B. melitensis Rev.1 vaccine for small ruminants is officially not recommended by the Government of India. Present study reports B. melitensis Rev.1 vaccinal antibodies detection in breeding sheep flock due to use of Brucella melitensis Rev1 vaccine. We investigated an organized sheep flock located in the southern part of India, consisting around 1200 sheep of breeds like Rambouillet and Bannur local breed ewes (600), Rambouillet lamb (300), crossbreds of Rambouillet and Dorper (200) and Rams (100) by random sampling of forty six sheep (vaccinated –20 and unvaccinated– 26) in order to detect antibodies against B.melitensis Rev–1 vaccinal strain. Among 20 vaccinated sheep serum samples tested, 19 (95%) and 13 (65%) and 19 (95%) were positive for anti Brucella antibodies by RBPT, SAT and iELISA respectively which is a major drawback of Rev–1 vaccine. This study further emphasized the need to initiate the control strategy in terms of suitable vaccines against B. melitensis in India in order to prevent import of Rev–1 vaccine by the farmers ; Not Available

Economic establishment and modernization has its share of disadvantages and one of the main aspects of concern is the pollution it is causing to the earth–be it land, air, and water. Due to the increase in the global population and the rising demand for food and other essentials, there has been a rise in the amount of waste being generated daily by each household. This waste is ultimately thrown into municipal waste collection centers from where it is collected by the area municipalities to be further thrown into the landfills and dumps. However, either due to resource crunch or inefficient infrastructure, not all of this waste gets collected and transported to the final dumpsites. If at this stage, the management and disposal is improperly done, it can cause serious impacts on health and problems to the surrounding environment. In order to avoid the problems caused by the increasing amount of solid waste generated every day, the Government of Malaysia through the Ministry of Housing and Local Government launched the practice of integrated solid waste management program, where the first step is the source reduction or reduce the generation followed by the resources recovery through the recycling and disposal of the residuals safely to the sanitary landfills. The objective of this paper is to identify the awareness of the communities in solid waste generation at Bandar Baru Bangi town. In order to achieve the objective, a survey has been conducted over the communities in the study area. The results showed that most of the community members have awareness on the solid waste generation issue and almost 80% communities have awareness on the types of solid waste they generate. Most of the communities members think before buy their household materials, which normally generate solid waste.