published_or_final_version / Physics / Master / Master of Philosophy

published_or_final_version / English Studies / Master / Master of Arts in Applied Linguistics

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / Civil Engineering / Master / Master of Philosophy

published_or_final_version / Education / Master / Master of Education

published_or_final_version / Education / Master / Master of Education

Interference alignment (IA) has been shown to provide all users of an interference channel with half the capacity achievable in an interference free point-to-point link resulting in linear sum capacity scaling with the number of users in the high SNR regime. The linear scaling is achieved by precoding transmitted signals to align interference subspaces at the receivers, given channel knowledge of all transmit-receive pairs, effectively reducing the number of discernible interferers. The theory of IA was derived under assumptions about the richness of the propagation channel; practical channels do not guarantee such ideal characteristics. This paper presents the first experimental study of IA in measured multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) interference channels. We show that IA achieves the claimed scaling factors in a wide variety of measured channel settings for a 3 user, 2 antennas per node setup. In addition to verifying the claimed performance, we characterize the effect of several realistic system imperfections such as channel estimation error, feedback delay, and channel spatial correlation, on sum rate performance. / text

Several alternatives to the Kuder and Richardson formula number 20 (KR20) were compared for accuracy using simulated and actual data sets. Coefficients by Loevinger (1948), Horst (1954), Raju (1982), and Cliff (1984) as well as the Kuder and Richardson formulae numbers 8 and 14 were examined. These alternative reliability coefficients were compared by (1) simulation of tests with varying degrees of item difficulty dispersion, subject proficiency, reliability, and length, and (2) use of the norming samples of the Curriculum Referenced Tests of Mastery (Charles E. Merrill Publishing Co., publisher) for grades four, six, and eight. Most of the coefficients examined proved no more accurate than the KR20 and several were decidedly worse. All coefficients, with the exception of Loevinger's, were affected by item difficulty dispersion. Two coefficients, the KR8 and Horst, were found to have potential as KR20 substitutes. These two coefficients are discussed with recommendations made as to the appropriate use of each one.

Researchers have suggested that knowledge of how to take a test decreases the validity of achievement test scores as measures of content knowledge. Further, teaching students test taking skills generally improves student achievement test scores. However, little research exists regarding the efficacy of commercially prepared materials for formal test-wiseness instruction. Fourth and fifth grade students in 15 elementary schools participated in this study. Students in the Volunteer Selected group received instruction in test taking skills using the Riverside Improving Test Taking Skills materials. Students in the Volunteer Not-Selected group received whatever test taking skill instruction their teachers provided as a result of wanting, but not being selected, to participate in the study. Students in the Control group received what was considered "normal" instruction in test taking skills. A gain score ANOVA of NCE scores from standardized testing was used to determine statistical significance on the Composite Battery and the Reading and Mathematics subtests. When reliable differences were indicated effect sizes were calculated. Formal instruction in test taking skills resulted in significant effects for fourth grade students on the Composite battery and the Mathematics subtest. However, average gains for students in the Volunteer Not-Selected group were as great as for students who received instruction using the Riverside materials. Significant effects for the Reading subtest were indicated only for achievement level. Positive effects were indicated for fifth grade students in the Volunteer Not-Selected group on the Composite and Mathematics subtest. At the fourth grade differential effects were indicated for achievement level, sex, and SES, but not for ethnicity. At the fifth grade achievement level, sex, SES, and ethnicity resulted in differential effects for students in all three groups. In summary, test taking skill instruction appeared beneficial to fourth grade students regardless of whether the instruction was delivered using the Riverside materials or using teacher made or teacher collected materials. At the fifth grade data the results were less clear cut. Further research must be conducted before policies can be established and educators can use with confidence, or not use at all, commercially prepared test taking skill instructional materials.

The compilation, collection, analysis, and simulation of UPRP streamflow and water-quality information were undertaken in order to assess the expected levels and variability of the quantity and quality of the surface waters in relation to the meteorology and hydrology of the area--the intended objectives of the project--and the modes of system operation. Under the two major phases of the study, important aspects which were examined were the availability and adequacy of the data base, and the applicability of modeling schemes to simulate the observed properties of the data. The major objective in the operational hydrology phase was to test the applicability of operational hydrology in a tropical environment. A stochastic model was fitted to the streamflow data of the extended UPRP inflows in order to serve as a generator of synthetic monthly streamflows which are used as inputs to operational studies of the project. As an initial requirement, the historical record was augmented by means of regional estimation techniques and a statistical data augmentation scheme. The percent deviation method of data augmentation was selected and applied, based on the results of a comparison of four augmentation methods. Two normalizing transformations were applied on the augmented-historical data in order to express them as statistical variables amenable to synthesis. These were the logarithmic transformation and Harter's table interpolation scheme. A time series analysis applied on the normalized data prescribed the adoption of the separate-monthly Matalas model for synthesis. The application of the model yielded synthetic streamflows which satisfactorily reproduced the correlation coefficients, means, and standard deviations of the augmentedhistorical monthly flows. Model extensions and refinements were recommended in order to surmount model limitations. In general, the applicability of operational hydrology in a tropical environment has been demonstrated. The quality of the UPRP surface water was characterized in order to provide background information which is essential in determining the suitability of the water for fishery development in the reservoir, for irrigation, and for domestic and industrial use. The Pantabangan reservoir was characterized in terms of observed patterns of temperature, dissolved oxygen, and salinity. An annual cycle was observed which exhibits intermittently disturbed and moderate stratification in the wet season, full circulation and isothermal condition during the cool, windy, and dry months, and a short warm period favorable to stratification prior to the heavy rains. Atmospheric reaeration was identified to be the major contributor of dissolved oxygen to the reservoir water. The application of the Markofsky-Harleman predictive model for reservoir temperature and dissolved oxygen emphasized the need for substantial data on the hydrology, meteorology, hydrodynamics, and water quality in the reservoir which are required as model inputs. The best agreement between observed and predicted temperature and DO was obtained for cool, windy, and dry months of December to February. Limitations in the input data and in the assumed parameters were observed. The available and collected water-quality data in the reservoir and streams of the UPRP indicated a salinity level as low as or less than 100 ppm in the headwaters to as high as 300 ppm in the outflows from the irrigation service area. The surface water is essentially the alkaline-bicarbonate type. The heavy runoff during the wet season produces a dilution of the TDS, but causes the conveyance of considerable amounts of sediment to the reservoir and river channels. An approximate salt balance for the project area yielded estimates of net amounts of salts leached from the area per season.