A study to evaluate STS heads-up ascent trajectory performance employing a minimum-Hamiltonian optimization strategy

A study was conducted to evaluate the performance implications of a heads-up ascent flight design for the Space Transportation System, as compared to the current heads-down flight mode. The procedure involved the use of the Minimum Hamiltonian Ascent Shuttle Trajectory Evaluation Program, which is a three-degree-of-freedom moment balance simulation of shuttle ascent. A minimum-Hamiltonian optimization strategy was employed to maximize injection weight as a function of maximum dynamic pressure constraint and Solid Rocket Motor burnrate. Performance Reference Mission Four trajectory groundrules were used for consistency. The major conclusions are that for heads-up ascent and a mission nominal design maximum dynamic pressure value of 680 psf, the optimum solid motor burnrate is 0.394 ips, which produces a performance enhancement of 4293 lbm relative to the baseline heads-down ascent, with 0.368 ips burnrate solid motors and a 680 psf dynamic pressure constraint. However, no performance advantage exists for heads-up flight if the current Solid Rocket Motor target burnrate of 0.368 ips is used. The advantage of heads-up ascent flight employing the current burnrate is that Space Shuttle Main Engine throttling for dynamic pressure control is not necessary

Barbier reaction in the regime of metal oxide: the first example of carbonyl allylation mediated by tetragonal tin(II) oxide

Facile synthesis of homoallylic alcohols is achieved from allyl halides and aldehydes or ketones over an all-oxide heterogenous media involving β-SnO and catalytic Cu2O

Nai talim today: some issues and possibilities

To understand Gandhi’s educational ideas one has to explicitly keep Dewey’s following quote in mind “We will know what type of education to provide, if we know what type of society we want”

Children and their parents come running into school

In my villages, poor families have 5-15 country chicken. children know that when family come visiting, you have to prepare a chicken dish, and when you suddenly need some money, a few chicken can be sold off. but twice or thrice a year there are these epidemics and many chicken die. yes, they know that there are some veterinarians, both government and private. but who will come to treat 15 chicken? and then they charge too much too. so class 6, 7 and 8 kids were asked, why don't you immunize the chicken yourself? they are incredulous "we are only small chicken", they explained. "how can we do this?" and then one child said - why not? that was the begining in 8 villages, about 200 adolescents learnt how to immunize chicken

Transition metal catalysed Grignard-like allylic activation across tetragonal tin(II) oxide

The reaction of allyl halide and a carbonyl compound under the aegis of tetragonal tin(II) oxide and catalytic d8, d10 metal complexes provides the corresponding homoallylic alcohol, via a novel allyl tin intermediate

Nurturing the citizenry of the future: community involvement in schools

The National Curriculum Framework 2005 has stated that “fertile and robust education is always created, rooted in the physical and cultural soil of the child, and nourished through interaction with parents, teachers, fellow students and the community.” However, there can be various forms of community involvement in schools. Right of Children to Free and Compulsory Education, 2009 (RTE Act) is a legislation which seeks to provide quality education for all children in the age group of 6-14 years. In this Act itself, specific provisions have been made for democratisation of schools and for parents and local communities to play their due roles in shaping and running of the schools in the form of School Management Committees (SMC) and preparation of School Development Plan. Although a good move, such involvements can be viewed as technical interventions and the goal is to see that the school runs effectively. However, our children are today's (and tomorrow's) citizens too. The relationship between the community and the school must be organic and something linked to the future of the child and the community. There are few instances in our country where successful school-community links have been possible –and they also contributed some meaning to the education. We are going to discuss three of them: the Vigyan Ashram IBT model, Sikshan-Mitra program in Ashram schools, both in Maharashtra; and Swanirvar experiment in West Benga