2,541 research outputs found
Quantum Mechanical Breaking of Local GL(4) Invariance
We consider the gravitational coupling of a scalar field, in a reformulation
of General Relativity exhibiting local GL(4) invariance at the classical level.
We compute the one-loop contribution of the scalar to the quantum effective
potential of the vierbein and find that it does not have GL(4) invariance. The
minima of the effective potential occur for a vierbein which is proportional to
the unit matrix.Comment: 9 pages, plain-TeX, no figure
Calculation of dynamic loadings in the drive with protection-compensated clutch
Наведено теоретичні залежності та розрахункові схеми для визначення динамічних навантажень у приводі із запобіжно-компенсуючою муфтою. Виведено умову рівноваги елементів зачеплення півмуфти з обоймою. Наведено графічні залежності впливу основних конструктивно-силових параметрів елементів зачеплення муфти на значення обертового моменту. Досліджено вплив амортизуючої пружини даного пристрою на величину обертового моменту при неспіввісності валів. Запропоновано практичні рекомендації для проектування аналогічних пристроїв.Theoretical dependences and settlement schemes for definition of dynamic loadings in a drive with protective-compensating clutch are resulted. The condition of balance of elements of gearing half-coupling with a holder is deduced. Graphic dependences of influence of the basic design data-power of elements of gearing clutch on value of a rotating moment are resulted. Influence buffer spring of the given device on size of a rotating moment is investigated at not alignment shaft. Practical recommendations for designing similar devices are offered
Parametric Mass Modeling for Mars Entry, Descent and Landing System Analysis Study
This paper provides an overview of the parametric mass models used for the Entry, Descent, and Landing Systems Analysis study conducted by NASA in FY2009-2010. The study examined eight unique exploration class architectures that included elements such as a rigid mid-L/D aeroshell, a lifting hypersonic inflatable decelerator, a drag supersonic inflatable decelerator, a lifting supersonic inflatable decelerator implemented with a skirt, and subsonic/supersonic retro-propulsion. Parametric models used in this study relate the component mass to vehicle dimensions and mission key environmental parameters such as maximum deceleration and total heat load. The use of a parametric mass model allows the simultaneous optimization of trajectory and mass sizing parameters
Reusable Rocket Engine Operability Modeling and Analysis
This paper describes the methodology, model, input data, and analysis results of a reusable launch vehicle engine operability study conducted with the goal of supporting design from an operations perspective. Paralleling performance analyses in schedule and method, this requires the use of metrics in a validated operations model useful for design, sensitivity, and trade studies. Operations analysis in this view is one of several design functions. An operations concept was developed given an engine concept and the predicted operations and maintenance processes incorporated into simulation models. Historical operations data at a level of detail suitable to model objectives were collected, analyzed, and formatted for use with the models, the simulations were run, and results collected and presented. The input data used included scheduled and unscheduled timeline and resource information collected into a Space Transportation System (STS) Space Shuttle Main Engine (SSME) historical launch operations database. Results reflect upon the importance not only of reliable hardware but upon operations and corrective maintenance process improvements
Paper Session I-C - Landsat-7 Managing the Transition
The Land Remote Sensing Policy Act of 1992, (Public Law PL102-555) recognized the importance of continuous collection and utilization of land remote se J?mg data from space. The Department of Defense (DoD) and the National Xmnautics and Space Administration (NASA) were responsible as the Landsat Program Management. The program proceeded with DOD developing the satellite and NASA developing the ground system. Each agency was for responsible its respective technical and budget requirements
Evaluasi Produksi Alat Angkut Jenis Hino Dutro Fm 260 Ti Dan Hino Dutro Fm 320 Ti Pada Pengangkutan Batubara Dari Front Area Pit Air Talang Seginim Ke Stockpile Run of Mine (Rom) Air Talang Seginim PT. Danau Mas Hitam, Bengkulu
PT Danau Mas belum dapat mencapai terget produksi yang telah direncankan, hal itu disebabkan oleh beberapa faktor diantaranyakurangnya efektifitas dan efisiensi kerja alat angkut, efektifitas waktu kerja,kondisi jalan angkut, dan keahlian oprator. Untukmeningkatkan produksi batubara dilakukan dengan analisis aktual lapangan terhadap cycle time, Waktu Kerja Alat Angkut,Mechanical Availability, Physical Availability , Use Availability, Effective Utilization, kondisi jalan angkut, yang diperoleh dari datayang ada dilapangan, yang akan berpengaruh terhadap waktu effesiensi kerja, salah satu perbaikan yang dilakukan adalahpeningkatan waktu kerja efektif dengan cara estimasi waktu kerja yaitu menghilangkan waktu hambatan yang direncankan, efesiensikerja aktual PT Danau Mas Hitam diperoleh sebesar 51,45 % kemudian dilakukan estimasi perbaikan diperoleh waktu effesiensikerja sebesar 67,67 %, yang terdiri dari waktu hambatan sebesar 2145,66 jam/tahun dan waktu kerja efektif sebesar 4554,34jam/tahun. Proses perbaikan yang dilakukan terhadap waktu efesiensi meninkatkan produksi alat angkut sebesar 10.416,6ton/tahun jenis hino dutro 500 FM 260 Ti dan sebesar 3.595,1 ton/ tahun jenis hino dutro 500 FM 320 Ti. Upaya-upaya lain yangjuga dapat dilakukan dalam peningkatan produksi batubara adalah perbaikan dan perawatan jalan angkut, penambahan jumlah alatangkut dan peningkatan ketrampilan operator
- …