ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / Adaptive modulation is a communication technique capable of maximizing throughput while guaranteeing a fixed symbol error rate (SER). However, this technique requires instantaneous channel state information at the transmitter. This can be obtained by predicting channel states at the receiver and feeding them back to the transmitter. Existing algorithms used to predict single-input single-output (SISO) channels with recurrent neural networks (RNN) are extended to multiple-input multiple-output (MIMO) channels for use with adaptive modulation and their performance is demonstrated in several examples.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / The accuracy of channel estimation plays a crucial role in the demodulation of data symbols sent across an unknown wireless medium. In this work a new analytical expression for the channel estimation error of a multiple input multiple output (MIMO) system is obtained when the wireless medium is continuously changing in the temporal domain. Numerical examples are provided to illustrate our findings.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / The accuracy of channel estimation plays a crucial role in the demodulation of data symbols sent across an unknown wireless medium. In this work a new analytical expression for the channel estimation error of a multiple input multiple output (MIMO) system is obtained when the wireless medium is continuously changing in the temporal domain. Numerical examples are provided to illustrate our findings. Space-time (ST) coding using Continuous Phase Modulation (CPM) has spectral advantages relative to linear modulations. In spite of the spectral benefits, Space-Time Trellis Codes (STTC) using the CPM implementation of Minimum Shift Keying (MSK) scheme has inherent inphase and quadrature interference, when the received complex baseband signal is the input into the matchfilter to remove the shaped sinusoid pulses. In this paper a novel optimum transmitting and detecting structure for STTC-MSK is proposed. Treating the Alamouti scheme as an outer code, each STTC MSK waveform frame is immediately followed by the orthogonal conjugate waveform frame at the transmit side. At the receiver first orthogonal wave forming is applied, then a new time-variant yet simple trellis structure of the STTC-MSK signals is developed. This STTC-MSK detector is absolutely guaranteed to be I/Q interference-free and still keeps a smaller computation load compared with STTC-QPSK. Simulations are made over quasi-static AWGN fading channel. It is shown that our detector for ST-MSK has solved the I/Q interference problem and has around 2.8 dB gain compared with the Alamouti Scheme and 3.8 dB gain for bit error rate at 5 X 10^(-3) in a 2 by 1 Multiple Input Single Output system.

Spatial modulation (SM) is a transmission technique proposed for multiple–input multiple– output (MIMO) systems, where only one transmit antenna is active at a time, offering an increase in the spectral efficiency equal to the base–two logarithm of the number of transmit antennas. The activation of only one antenna at each time instance enhances the average bit error ratio (ABER) as inter–channel interference (ICI) is avoided, and reduces hardware complexity, algorithmic complexity and power consumption. Thus, SM is an ideal candidate for large scale MIMO (tens and hundreds of antennas). The analytical ABER performance of SM is studied and different frameworks are proposed in other works. However, these frameworks have various limitations. Therefore, a closed–form analytical bound for the ABER performance of SM over correlated and uncorrelated, Rayleigh, Rician and Nakagami–m channels is proposed in this work. Furthermore, in spite of the low–complexity implementation of SM, there is still potential for further reductions, by limiting the number of possible combinations by exploiting the sphere decoder (SD) principle. However, existing SD algorithms do not consider the basic and fundamental principle of SM, that at any given time, only one antenna is active. Therefore, two modified SD algorithms tailored to SM are proposed. It is shown that the proposed sphere decoder algorithms offer an optimal performance, with a significant reduction of the computational complexity. Finally, the logarithmic increase in spectral efficiency offered by SM and the requirement that the number of antennas must be a power of two would require a large number of antennas. To overcome this limitation, two new MIMO modulation systems generalised spatial modulation (GNSM) and variable generalised spatial modulation (VGSM) are proposed, where the same symbol is transmitted simultaneously from more than one transmit antenna at a time. Transmitting the same data symbol from more than one antenna reduces the number of transmit antennas needed and retains the key advantages of SM. In initial development simple channel models can be used, however, as the system develops it should be tested on more realistic channels, which include the interactions between the environment and antennas. Therefore, a full analysis of the ABER performance of SM over urban channel measurements is carried out. The results using the urban measured channels confirm the theoretical work done in the field of SM. Finally, for the first time, the performance of SM is tested in a practical testbed, whereby the SM principle is validated.

Thesis (PhD (Agric))--Stellenbosch University, 2013. / ENGLISH ABSTRACT: It is common practice in computable general equilibrium (CGE) models that the output composition of multi-product industries remains constant despite changes in relative prices of products. The results of any scenario will show that products produced by a single industry will still be produced in the same ratio to each other as reflected by the base data. The objective of the study was to develop a CGE model for South Africa in which this assumption of fixed composition of output can be selectively relaxed. In order to allow industries to adjust their output composition in response to changes in relative prices of products a Constant Elasticity of Transformation (CET) function and the related first order condition were incorporated into an existing CGE model. This alternative specification of an output transformation function in the model enables the modeller to allow selected multi-product industries to increase production of products that show greater price increases relative to other products. The first order condition of the CET function determines the optimal combination of products for each industry. With the inclusion of the CET function there is a trade-off between theoretical rigour of the model and realism of the results, therefore an assumption of input-output separability was introduced as a way of recognising that the inclusion of a CET function violates the assumption that prices in the same row of a social accounting matrix (SAM) are equivalent. The model was calibrated with a SAM for South Africa for 2007 that was developed for purposes of this study. Set controls were included in the model to generalise the model in order that it can be calibrated with data from other countries as well. The SAM for South Africa contains provincial level information in the accounts for agriculture, labour and households. The agricultural industries are defined by geographical area, hence these industries are particularly good examples of multi-product industries that respond to relative price changes when determining production levels of individual products. The adjusted CGE model was used to analyse four scenarios focusing on selected issues mentioned in the National Development Plan for South Africa released by the National Planning Commission in 2011. The scenarios relate to increases in fruit exports as a result of global positioning, technical efficiency improvements for the agricultural sector through continued research and development, factor productivity growth in government and selected services sectors resulting from fighting corruption and curbing strikes, and augmenting the supply of skilled labour through an improvement in the quality of education. The results of the adjusted model show the desired effect: producers produce relatively more of the products for which they can get a relatively higher price and vice versa. This holds true regardless of whether the level of industry output increases or decreases. The impact of the model adjustment and the effects of changes in the levels of elasticities and choice of variables to close the model were analysed as part of the sensitivity analyses. The impact of changes in the functional form, elasticities and model closures on results, are different for each scenario. / AFRIKAANSE OPSOMMING: Dit is erkende praktyk in berekenbare algemene ewewigsmodelle dat die verhoudings waarin produkte tot mekaar geproduseer word deur multi-produk industrieë konstant gehou word, ongeag veranderings in relatiewe pryse van produkte. Die resultate van enige senario sal dus aandui dat die produkte wat deur 'n enkele industrie geproduseer word steeds in dieselfde verhouding tot mekaar geproduseer sal word, soos weerspieël in die basis data. Die doel van die studie was om 'n berekenbare algemene ewewigsmodel vir Suid-Afrika te ontwikkel wat die aanname dat die samestelling van elke industrie se uitset onveranderbaar is, selektief kan verslap. Om toe te laat dat industrieë die samestelling van uitset kan aanpas namate die relatiewe pryse van produkte verander, is 'n Konstante Elastisiteit van Transformasie funksie en die gepaardgaande eerste orde voorwaarde in 'n bestaande berekenbare algemene ewewigsmodel ingesluit. Die eerste orde voorwaarde bepaal die optimale verhoudings waarin produkte geproduseer moet word. Met die insluiting van die Konstante Elastisiteit van Transformasie funksie word teoretiese korrektheid van die model ingeboet in ruil vir meer realistiese resultate, dus is die aanname van inset-uitset onafhanklikheid gemaak en daardeur word ook erken dat as gevolg van die insluiting van die Konstante Elastisiteit van Transformasie funksie word daar nie meer voldoen aan die aanname data alle pryse in dieselfde ry van die sosiale rekeninge matriks (SRM) aan mekaar gelyk is nie. Die model is gekalibreer met 'n SRM vir Suid-Afrika vir 2007 wat vir doeleindes van die studie ontwikkel is. Deur die insluiting van kontroles vir versamelings is die model veralgemeen sodat die model ook met data van ander lande gekalibreer kan word. Die SRM vir Suid-Afrika se rekeninge vir landbou, arbeid en huishoudings bevat inligting op provinsiale vlak. Die landbou industrieë is volgens geografiese gebiede afgebaken en is dus besonder goeie voorbeelde van multi-produk industrieë wat reageer op relatiewe prys veranderings wanneer die produksievlakke van afsonderlike produkte bepaal word. Die aangepaste algemene ewewigsmodel is gebruik om vier senarios te ondersoek wat fokus op geselekteerde onderwerpe vervat in die Nasionale Ontwikkelingsplan wat deur die Nasionale Beplanningskommissie van Suid Afrika in 2011 vrygestel is. Die senarios hou verband met 'n styging in vrugte uitvoere as gevolg van globale posisionering, tegniese produktiwiteitsverhogings vir die landbousektor deur volgehoue navorsing en ontwikkeling, verhoging in die produktiwiteit van produksiefaktore van die regering en geselekteerde dienste sektore deur die aanspreek van korrupsie en vermindering in stakings, en die toename in geskoolde arbeid deur 'n verbetering in die kwaliteit van onderwys. Resultate van die aangepaste model toon die gewenste uitwerking: produsente produseer relatief meer van die produkte waarvoor hulle 'n relatiewe hoër prys kan kry, en omgekeerd. Dit geld ongeag of daar 'n verhoging of 'n verlaging in die vlak van die industrie se uitset is. Die impak van die modelaanpassing, die effek van veranderings in die vlakke van elastisiteite en die keuse van veranderlikes om die model te sluit, is geanaliseer as deel van die sensitiwiteitsanalises. Die impak van veranderings in die funksionele vorm, elastisiteite en modelsluiting op resultate, is verskillend vir elke senario.

The primary objective of this study was to estimate the impact that an increase in recreational expenditures, resulting from water quality improvements of Klamath Lake, would have upon the Klamath County economy. As the sales of the economy expand to serve the needs of the recreationists, real benefits will be forthcoming to the businesses and households of the county in the forms of more business and higher incomes. To estimate the total impact of the increased volume of recreational expenditures that may be made in the economy, the economic relationships of the local economy had to be determined. Primary data were collected from business firms in the county to construct an input-output model of the county's economy. The level of recreational expenditures that would be made in the county as the water quality of the lake improved were estimated. This was done for two different stages of water quality improvement. The estimated levels of recreational expenditures were then analyzed within the input-output framework to estimate the total increase in the sales of the economy and to estimate the increase in income of households in the county. / Graduation date: 1971

Interindustry, or input-output analysis is a widely used economic tool in regional analysis. This study investigates the relative worth of alternative types of input data for such models. Primary data are defined as first-hand, or survey data; secondary data are defined as second-hand, or published data. Procurement of primary data is generally much more expensive than for secondary data. Most regional economists have long held that, in general, primary data are superior to secondary data for regional investigations. This study attempts to assess the value of primary versus secondary data in view of the wide variation in collection costs. Two recently published input-output studies for the 1958-60 Arizona economy were utilized to accomplish this goal. One model used mostly primary data; the second model was compiled entirely from secondary data sources. Following careful considerations of base-period differences, geographical overlap, and sector definitions, two models-- the ARZ and the CRB--were constructed from the two source studies so as to be commensurable for statistical comparisons. The ARZ model was derived from the source study that was compiled entirely from secondary data sources; the CRB model was compiled from the source study that used mostly primary input data. Several nonparametric statistical tests were utilized on several components of the ARZ and CRB models to test for statistical similarities and dissimilarities. In general, analyses indicate strong statistical similarity between the two derived models for aggregative I-0 characteristics such as entire matrices and output multipliers, but less similarity for less aggregative components such as sub-matrices and columns of matrices. For example, comparisons between entire technical and between interdependency matrices fail to reject the null hypothesis of no median difference at the alpha level of 5 per cent. At still more unaggregated component analysis, such as for columns within technical and interdependency columns a reasonable degree of statistical similarity persisted. One chapter (V) focuses on the two derived models as they relate to water resources planning implications for Arizona. Results are similar to those for the non-water analyses; however, in the case of weighted water multipliers the similarities between the ARZ and CRB models are remarkably close. Based on an assumed short-run change of 10 per cent in deliveries to final demand for all sectors in the economy, the models differed in predictions of induced aggregate water requirements by only 9000 acre-feet of water, or less than 2 per cent. Results from the study cast doubt on the commonly held assumption of primary-data supremacy in regional interindustry studies. Results also indicate that the most important component for regional economic analysis is the final demand for each sector rather than the interindustry flows. This follows from the narrow clustering of values for output multipliers consistently observed in regional I-0 studies, and reaffirmed in this study. Therefore, students of regional economies are advised to spend marginal resources (money, time, energy) compiling more accurate final demand vectors rather than developing more accurate endogenous interindustry flows.

IEEE 802.11n Wireless Local Area Networks (WLANs) employ Multiple-Input-Multiple-Output (MIMO), which significantly boosts the raw data rate at the Physical layer (PHY). But the potential of enhancing Medium Access Control (MAC) layer efficiencies by MIMO is still in its early stage and is the aim of the research in this thesis. Many existing works in this field mainly employ distributed MIMO spatial multiplexing/Multi-User Detection (MUD) technique and stream sharing to enable multiple simultaneous transmissions. Most works require synchronization among multiple transmissions, split the channel, and aim for single-hop networks. In this thesis, a novel Hybrid Carrier Sense (HCS) framework is proposed, mainly at the MAC layer to exploit the power of MIMO. HCS senses the channel availability jointly by the virtual carrier sense and physical carrier sense. HCS does not require synchronization among nodes; each node independently and locally determines when to start its transmission. HCS not only shares the channel, but also exploits the bi-directional handshakes of the wireless transmissions and increases the number of simultaneous stream transmissions. For a network with M antennas in each node, HCS can accommodate 2x(M-1) streams instead of M streams achieved by all other existing works. Moreover, HCS is aimed for multi-hop wireless ad hoc networks, in which the hidden terminal, exposed terminal, and deafness problems greatly degrade network performance. The HCS framework incorporates solutions to these problems. HCS is implemented in an NS2 network simulator and the performance evaluation shows that HCS significantly outperforms MIMO-enabled IEEE 802.11 (in which MIMO is only used for enhancing the raw data rate in the physical layer), resulting in higher aggregate throughput, packet delivery ratio and fairness in multi-hop wireless ad hoc networks. The HCS framework will be in wide use in the future generation of wireless networks and opens up more research possibilities. Some ideas in the HCS framework can be applied not only for MIMO, but also for many other techniques surveyed in this thesis; or we may combine them with HCS to further boost the network performance. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2013-10-15 21:46:15.983

Lietuvių kalbotyroje atlikta nemažai kalbos įsisavinimo tyrimų, tačiau nedaug dėmesio skirta klausimų vartojimui ir įsisavinimui. Klausimų struktūros sudėtingumą lemia daug lingvistinių veiksnių: sintaksės, semantikos, pragmatikos taisyklės, todėl juos suvokti ir vartoti ankstyvajame amžiuje vaikams yra sunku. Šiame darbe analizuojamas specialiųjų klausimų įsisavinimas. Tai klausimai, kuriais prašoma įvardinti konkretų dalyką: veiksmo atlikėją, veiksmą, veikiamąją vietą, laiką, daikto požymį, priežastį ir kt. Analizuojant specialiųjų klausimų įsisavinimą, aptariamas ir šių klausimų vartojimas tėvų kalboje, skirtoje vaikams. Tad šio tyrimo rezultatai taip pat atskleidžia vaikų ir tėvų kalbos ryšį bei poveikį specialiųjų klausimų įsisavinimo raidai. / Many studies on language acquisition have been done in Lithuanian linguistics but little attention was paid to the use and acquisition of wh-questions, which is determined by a number of linguistic factors: the syntax, semantics, pragmatics rules. Therefore comprehension and production of these questions difficult for young children to comprehend and produce questions, especially at an early age. The acquisition of wh-questions is the main aim of this study. These are questions which are asked to name a specific thing: the performer of the action, the action, the place, the time, the features of the object, reason and others. Alongside with the acquisition of wh-questions, the use of wh-questions in the input speech is discussed, so the results of this study also show the correlation between input and output, in our case, the influence on the development of wh- questions.

The purpose of this study was to explore the efficacy of two existing pulse contour analysis (PCA) models for estimating cardiac stroke volume from the arterial pressure waveform during kicking ergometer exercise and head-up tilt manoeuvres. Secondly, one of the existing models was modified in an attempt to enhance its performance. In part I, seven healthy young adults repeated two submaximal exercise sessions on a kicking ergometer, each with three different sets of steady-state cardiac output comparisons (pulsed Doppler vs. pulse contour). Across all exercise trials regression results were found to be PCA = 1. 23 x Doppler-1. 38 with an r2 = 0. 51. In part II, eight young and eight older male healthy subjects participated in a head-up tilt experiment. Cardiac output comparisons were again performed during the supine and tilt conditions using pulsed Doppler and pulse contour cardiac output. Regression results revealed that PCA performed best during supine conditions and preferentially on the older subjects. In all instances, impedance-calibrated pulse contour analysis will provide reasonable beat-by-beat cardiac output within very narrow confines and will result in a progressively more significant bias as cardiovascular dynamics change. In addition, it appears that heart rate variability negatively influences beat-by-beat pulse contour cardiac output results, further limiting application of existing models.