Segment Oriented Compression Scheme for MOLAP Based on Extendible Multidimensional Arrays

Many statistical and MOLAP applications use multidimensional arrays as the basic data structure to allow the efficient and convenient storage and retrieval of large volumes of business data for decision making. Allocation of data or data compression is a key performance factor for this purpose because performance strongly depends on the amount of storage required and availability of memory. This holds especially for data warehousing environments in which huge amounts of data have to be dealt with. The most evident consequence of data compression is that it reduces storage cost by packing more logical data per unit of physical capacity. And improved performance is a net outcome because less physical data need to be retrieved during scan-oriented queries. In this paper, an efficient data compression technique is proposed based on the notion of extendible array. The main idea of the scheme is to compress each of the segments of the extendible array using the position information only. We compare the proposed scheme for different performance issues with prominent compression schemes.</p

Conceptual approach study of a 200 watt per kilogram solar array

Solar array candidate configurations (flexible rollup, flexible flat-pact, semi-rigid panel, semi-rigid flat-pack) were analyzed with particular attention to the specific power (W/kg) requirement. Two of these configurations (flexible rollup and flexible flat-pack) are capable of delivering specific powers equal to or exceeding the baseline requirement of 200 W/kg. Only the flexible rollup is capable of in-flight retraction and subsequent redeployment. The wrap-around contact photovoltaic cell configuration has been chosen over the conventional cell. The demand for ultra high specific power forces the selection of ultra-thin cells and cover material. Based on density and mass range considerations, it was concluded that 13 micrometers of FEP Teflon is sufficient to protect the cell from a total proton fluency of 2(10 to the 12th power) particles/sq cm over a three-year interplanetary mission. The V-stiffened, lattice boom deployed, flexible substrate rollup array holds the greatest promise of meeting the baseline requirements set for this study

Efficient structures for geosynchronous spacecraft solar arrays. Phase 1, 2 and 3

Structural concepts for deploying and supporting lightweight solar-array blankets for geosynchronous electrical power are evaluated. It is recommended that the STACBEAM solar-array system should be the object of further study and detailed evaluation. The STACBEAM system provides high stiffness at low mass, and with the use of a low mass deployment mechanism, full structural properties can be maintained throughout deployment. The stowed volume of the STACBEAM is acceptably small, and its linear deployment characteristic allows periodic attachments to the solar-array blanket to be established in the stowed configuration and maintained during deployment

Economic analysis of the design and fabrication of a space qualified power system

An economic analysis was performed to determine the cost of the design and fabrication of a low Earth orbit, 2 kW photovoltaic/battery, space qualified power system. A commercially available computer program called PRICE (programmed review of information for costing and evaluation) was used to conduct the analysis. The sensitivity of the various cost factors to the assumptions used is discussed. Total cost of the power system was found to be $2.46 million with the solar array accounting for 70.5%. Using the assumption that the prototype becomes the flight system, 77.3% of the total cost is associated with manufacturing. Results will be used to establish whether the cost of space qualified hardware can be reduced by the incorporation of commercial design, fabrication, and quality assurance methods

Technology for large space systems: A special bibliography with indexes

This bibliography lists 460 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1968 and December 31, 1978. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design in the area of the Large Space Systems Technology (LSST) Program. Subject matter is grouped according to systems, interactive analysis and design, structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, and flight experiments

3d Morphing And Shape Transformation Using Slices

Secara umum istilah ’Transformasi Rupa Bentuk’ bermaksud transformasi sebuah objek kepada sebuah objek yang lain. Apabila transformasi rupa bentuk melibatkan dua buah objek iaitu objek sumber dan objek destinasi, dan terdapat pelenyapan rupa bentuk objek sumber kepada objek destinasi secara beransur-ansur, berterusan dan serentak maka transformasi rupa bentuk ini dipanggil ’Pemorfan’. Kebanyakan algoritma transformasi rupa bentuk sedia ada melibatkan banyak campur tangan pengguna, tidak boleh diskalakan dengan rapi apabila bilangan objek input lebih daripada dua dan tidak boleh diskalakan dalam persekitaran perkomputeran selari dan teragih apabila diperlukan. Tesis ini menyentuh isu-isu tersebut dengan mencadangkan algoritma pemorfan 3D yang novel menggunakan hirisan. Pada mulanya objek sumber dan destinasi disusur, dan hirisan dijana daripada penyusuran berkenaan. Penyusuran data tertentu mungkin menjana hirisan yang tidak semestinya selari antara satu sama lain. Bilangan hirisan yang sama dijana bagi kedua-dua objek sumber dan destinasi. Sempadan kedua-dua objek berkenaan diekstrak. Sempadan berkenaan kemudiannya disusur pada satah 2D dan ditransformasikan kepada masing-masing satu awan titik kontur. Interpolasi awan titik kontur sumber dan destinasi yang sepadan dilakukan, dan permukaan yang ditransformasikan dibina semula. Generally the term ‘Shape Transformation’ means transformation of one object into another object. When shape transformation involves two objects i.e. source object and destination object and there is gradual, continuous and simultaneous dissolvement of the shape of source object to destination object, it is called ‘Morphing’. Most of the existing shape transformation algorithms involve a lot of user intervention, do not scale well when the number of input objects is more than two and are not scalable in parallel and distributed computing environment whenever needed. This thesis addresses the above-mentioned issues by proposing a novel 3D morphing algorithm using slices. Firstly source and destination objects are traversed and slices are generated from this traversal. Traversal of a particular data may generate slices which may not be parallel to each other. Equal number of slices is generated for both source and destination objects. Boundaries of both objects are extracted. The boundaries are then traversed on a 2D plane and are transformed into a cloud of contour points each. Interpolation of the corresponding source and destination contour point clouds takes place and transformed surface is reconstructed

Large space structure experiments for AAP. Volume 3 - Crossed-H interferometer for long wave radio astronomy Final report, 15 Sep. 1966 - 15 Sep. 1967

Apollo Applications Program space erectable crossed-H interferometer for long wave radio astronomy experiments and evaluation of EVA in space maintenanc

The SOS Platform: Designing, Tuning and Statistically Benchmarking Optimisation Algorithms

open access articleWe present Stochastic Optimisation Software (SOS), a Java platform facilitating the algorithmic design process and the evaluation of metaheuristic optimisation algorithms. SOS reduces the burden of coding miscellaneous methods for dealing with several bothersome and time-demanding tasks such as parameter tuning, implementation of comparison algorithms and testbed problems, collecting and processing data to display results, measuring algorithmic overhead, etc. SOS provides numerous off-the-shelf methods including: (1) customised implementations of statistical tests, such as the Wilcoxon rank-sum test and the Holm–Bonferroni procedure, for comparing the performances of optimisation algorithms and automatically generating result tables in PDF and formats; (2) the implementation of an original advanced statistical routine for accurately comparing couples of stochastic optimisation algorithms; (3) the implementation of a novel testbed suite for continuous optimisation, derived from the IEEE CEC 2014 benchmark, allowing for controlled activation of the rotation on each testbed function. Moreover, we briefly comment on the current state of the literature in stochastic optimisation and highlight similarities shared by modern metaheuristics inspired by nature. We argue that the vast majority of these algorithms are simply a reformulation of the same methods and that metaheuristics for optimisation should be simply treated as stochastic processes with less emphasis on the inspiring metaphor behind them

The 29th Aerospace Mechanisms Symposium

The proceedings of the 29th Aerospace Mechanisms Symposium, which was hosted by NASA Johnson Space Center and held at the South Shore Harbour Conference Facility on May 17-19, 1995, are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, pointing mechanisms joints, bearings, release devices, booms, robotic mechanisms, and other mechanisms for spacecraft