College of Engineering Project Reports
Permanent URI for this collection
News
2540 Dole Street, Holmes 240
Honolulu, Hawaii 96822
Phone: (808) 956-7727
Fax: (808) 956-2291
info@eng.hawaii.edu
Browse
Recent Submissions
Item VSAT Data Network(Honolulu, Hawaii: PRIISM, Pacific Research Institute for Information Systems and Management, 1990) Abramson, NormanTwo general methods have been used to provide random access packet communications in Very Small Aperture (VSAT) data networks – Spread Spectrum (or CDMA) and ALOHA. In this paper we review the use of satellite channels for such networks and discuss certain basics aspects of the architecture of VSAT data networks. Although Spread Spectrum and ALOHA have different origins and are sometimes represented as competing technologies, they can in fact be characterized as different ways of viewing the same low dimensional signals in a high dimensional signal space. After a brief introduction to the architecture of VSAT networks we show how a simple linear transformation of conventional ALOHA packets leads to signals identical in all respects to the most common form of Spread Spectrum signals. We call the result of this transformation Spread ALOHA.
There are two practical consequences of this theoretical result. First, for the case of small earth stations it is not possible to find an access technique with a higher throughput than Spread ALOHA. Second, the use of different spreading sequences for different users in a packet network using Spread Spectrum is not necessary for user separation.
Item Spread ALOHA for VSATs(Honolulu, Hawaii: PRIISM, Pacific Research Institute for Information Systems and Management, 1986) Abramson, NormanSpread ALOHA is a multiple access protocol using conventional ALOHA packets spread in time, so that the packet contention interval at the output of the packet receiver is not increased. Packets transmitted using a Spread ALOHA protocol can overlap in the physical channel with high probability, but still be separated at the output of a matched filter, so that the probability of overlap at the receiver output is low. Spread ALOHA operation of a data channel combines several characteristics of ALOHA channels and Spread Spectrum channels. The use of Spread ALOHA can achieve certain efficiencies and simplicities of operation which are not possible in conventional ALOHA channels or conventional Spread Spectrum channels. In particular, for the case of a large number of small earth stations accessing a single satellite transponder in a data network, no signaling technique is possible which can achieve a higher average data throughput for a given average power and a given bandwidth than Spread ALOHA.
This report is preliminary only. It contains an explanation of the basic elements of a Spread ALOHA channel together with some notational material which serves to emphasize the connection between Spread ALOHA, conventional Spread Spectrum and algebraic coding theory. A more detailed report will be provided at a later date.
Item Research proposal to the Geothermal Division Energy Research and Development Administration(Hawaii Geothermal Project, University of Hawaii at Manoa, 1976-05-17) Shupe, JohnAddendum to proposal submitted May 17, 1976. The purpose of the funds requested in this proposal is to provide support with which to complete analysis and interpretation of the data and, through comparison with actual subsurface conditions, develop correlations on the reliability of the various methods of prediction. We also propose a limited number of field experiments designed to assist in the understanding of the reservoir dynamics. A synthesis of all pertinent data--from geosciences, from mathematical modeling, from drilling, from welltesting-- will contribute to a more complete understanding of the geothermal regime associated with this well.Item Research proposal submitted to the National Science Foundation, Research Applied to National Needs (RANN), Advanced Energy Research and Technology(University of Hawaii at Manoa, College of Engineering, 1974) Shupe, JohnHawaii Geothermal Project - Phase II. The Hawaii Geothermal Project was established to focus the resources of the State and the University of Hawa-ii on a coordinated research effort leading to the development of geothermal power on the Big Island of Hawaii. Phase I of the Project was initiated in the summer of 1973 with a $252,000 grant from NSF-RANN, supplemented by $100,000 each from the State and the County of Hawaii. This $452,000 budget was organized into a multidisciplinary research effort in the following program areas: (1) Geophysical - exploratory surveys to define the most favorable areas for geothermal investigations; (2) Engineering - analytical models to assist in interpretation of geophysical results, and studies on energy recovery from hot brine; and (3) Socioeconomic- legal and regulatory aspects of ownership and administration of geothermal resources, and economic planning studies on the impact of geothermal power.Item Research proposal submitted to the National Science Foundation, Research Applied to National Needs (RANN)(University of Hawaii at Manoa, 1973)Hawaii is generously endowed with many forms of natural energy--wind, wave, solar, and geothermal--all potentially low-pollution power sources. This proposal requests RANN funding to assist in developing that resource which appears to have the greatest potential for meeting the State's expanding power requirements--geothermal energy. In honor of Pele, the Hawaiian Goddess of Fire and resident of island volcanoes, the program is entitled Pele Energy Laboratory Experiments. The PELE Project involves an interdisciplinary team of fifty-four researchers from throughout the University of Hawaii System who, in collaboration with a distinguished group of advisors and consultants, will engage in thirty-eight separate research tasks related to geothermal power. These scientific investigations are grouped into three programs: a) Geophysical, b) Engineering, and c) Environmental and Socioeconomic; and include both short- and long-range research studies on the identification, generation, and utilization of geothermal energy. A secondary objective of the PELE Project is to provide the geophysical data and engineering technology to assist in the early development of geothermal power on the Big Island of Hawaii. Consequently, the drilling of deep test holes and planning for construction of a prototype geothermal power plant are included in this proposal. The prototype plant, in addition to providing essential data on the reservoir characteristics of the geothermal field, will serve as an observation and working laboratory for engineers and scientists from throughout the world. This project has the interest and support of both State and County governments, as well as the private utilities on the three major islands. The potential is excellent for involving education, private interests, and government at the local, state and federal levels in this significant research project for expanding the technology base on geothermal energy and for developing a low-pollution power source for Hawaii and the Nation.Item Hawaii Natural Energy Institute daily drilling report from 11-02-90 to 02-27-91(Hawaii Natural Energy Institute, University of Hawaii at Manoa, 1991) Hawaii Natural Energy Institute, University of Hawaii at ManoaInformation includes hole number, date, depth, time, personnel involved, and additional information.Item Reservoir assessment of the Puna Geothermal Field, Island of Hawaii(GeothermEx, Inc., 1989-07) GeothermEx, Inc.The first step in assessing a geothermal resource is to develop a hydrogeologic model which defines the three-dimensional distributions of temperature and pressure and relates these distributions to the geologic structures that control the flow of thermal fluid. An assessment of the available energy beneath the lease will be based on the temperature distribution, and the drilling plan will be based on the permeability distribution inferred from the hydrogeologic model. Surface geology, interpreted from aerial photographs, and subsurface geology, inferred from geophysical data, are described in Section 2 of this report. Subsurface temperature and pressure distributions are described in Sections 3.1 through 3.3, and section 3.4 summarizes the hydrogeological model developed from interpreting the temperature and pressure distribution patterns in relation to the geology described in Section 2. Section 4 summarizes the results of well tests, including the chemistry of the thermal fluid. Section 5 describes the volumetric estimate of reserves.Item Performance matching and predicting of a geothermal reservoir(University of Hawaii at Manoa, 1976-08) Seki, Arthur S.The initial conditions (physical and chemical state) of a geothermal reservoir and its fluids are important information needed in geothermal reservoir engineering for determining the future productivity of the reservoir. An optimization scheme was employed to minimize the least squares function and determine the optimum initial conditions. Using the mass, energy, and volumetric balance equations, the initial param-Beters were obtained by matching the production data plot of average reservoir pressure versus cumulative mass produced for a compressed liquid, saturated liquid-steam, and superheated steam reservoir. Once a good curve match was attained, the performance projection of the geothermal reservoir was made at different production rates. A successful curve match was found to be highly dependent on the constraints chosen in the optimization scheme. Mass influx, as well as porosity also proved to be an influencing factor in the determination of the initial conditions.Item Computer performance matching and prediction of geothermal reservoirs : technical report no. 22(University of Hawaii at Manoa, 1977-03-14) Seki, Arthur S.; Chen, Bill H.; Takahashi, Patrick K.The initial conditions (physical and chemical state) of a geothermal reservoir and its fluids are important information needed in geothermal reservoir engineering for determining the future productivity of the reservoir. An optimization scheme was employed to minimize the least squares function and determine the optimum initial conditions. Using the mass, energy, and volumetric balance equations, the initial parameters were obtained by matching the production data plot of average reservoir pressure versus cumulative mass produced for a compressed liquid, saturated liquid-steam, and superheated steam reservoir. Once a good curve match was attained, the performance projection of the geothermal reservoir was made at different production rates. A successful curve match was found to be highly dependent on the constraints chosen in the optimization scheme. Mass influx, as well as porosity also proved to be an influencing factor in the determination of the initial conditions. The computer prediction model is presently being used to assess reservoir conditions for the Hawaii Geothermal Project Well A, believed to be the hottest producing geothermal well in the world.Item HNEI's documents for SOH-3(Hawaii Natural Energy Institute, University of Hawaii at Manoa, 1990-09) Hawaii Natural Energy Institute, University of Hawaii at ManoaFrom the cover letter: "The University of Hawaii formally requests your approval to initiate drilling activities for a Scientific Observation Hole (SOH 3) in the area (TMK) 1-2-10:03) under Conservation District Use Permit (HA 12/20/85-1830) issued to the Estate of James Campbell. SOH 3 is to be located on the True/Mid-Pacific alternate drill site No. 2, about 3,000 feet north-north-west of their present drilling operations. Access to this drill site will be by a new road starting from True/Mid-Pacific's drill site. Only a portion (approximately a quarter acre plus access road around the drill site) of the True/Mid-pacific alternate drillsite No. 2 will be grubbed and graded for our operations."