Low-Complexity Near-MAP Decoding of Large Non-Orthogonal STBCs Using PDA

Non-orthogonal space-time block codes (STBC) from cyclic division algebras (CDA) are attractive because they can simultaneously achieve both high spectral efficiencies (same spectral efficiency as in V-BLAST for a given number of transmit antennas) as well as full transmit diversity. Decoding of non-orthogonal STBCs with hundreds of dimensions has been a challenge. In this paper, we present a probabilistic data association (PDA) based algorithm for decoding non-orthogonal STBCs with large dimensions. Our simulation results show that the proposed PDA-based algorithm achieves near SISO AWGN uncoded BER as well as near-capacity coded BER (within 5 dB of the theoretical capacity) for large non-orthogonal STBCs from CDA. We study the effect of spatial correlation on the BER, and show that the performance loss due to spatial correlation can be alleviated by providing more receive spatial dimensions. We report good BER performance when a training-based iterative decoding/channel estimation is used (instead of assuming perfect channel knowledge) in channels with large coherence times. A comparison of the performances of the PDA algorithm and the likelihood ascent search (LAS) algorithm (reported in our recent work) is also presented.

Performance evaluation of an integrated solar water heater as an option for building energy conservation

Since a majority of residential and industrial building hot water needs are around 50 degrees C, an integrated solar water heater could provide a bulk source that blends collection and storage into one unit. This paper describes the design, construction and performance test results of one such water-heating device. The test unit has an absorber area of 1.3 m(2) and can hold 1701 of water, of which extractable volume per day is 1001. Its performance was evaluated under various typical operating conditions. Every morning at about 7:00 a.m., 1001 of hot water were drawn from the sump and replaced with cold water from the mains. Although, during most of the days, the peak temperatures of water obtained are between 50 and 60 degrees C, the next morning temperatures were lower at 45-50 degrees C. Daytime collection efficiencies of about 60% and overall efficiencies of about 40% were obtained. Tests were conducted with and without stratification. Night radiation losses were reduced by use of a screen insulation.

Rannansiirtyminen ja ihmisen toimintaympäristön muutos Mätäjokilaakson alueella esihistoriallisella ajalla

In this thesis, I study the changing ladscape and human environment of the Mätäjoki Valley, West-Helsinki, using reconstructions and predictive modelling. The study is a part of a larger project funded by the city of Helsinki aming to map the past of the Mätäjoki Valley. The changes in landscape from an archipelago in the Ancylus Lake to a river valley are studied from 10000 to 2000 years ago. Alongside shore displacement, we look at the changing environment from human perspective and predict the location of dwelling sitesat various times. As a result, two map series were produced that show how the landscape changed and where inhabitance is predicted. To back them up, we have also looked at what previous research says about the history of the waterways, climate, vegetation and archaeology. The changing landscape of the river valley is reconstructed using GIS methods. For this purpose, new laser point data set was used and at the same time tested in the context landscape modelling. Dwelling sites were modeled with logistic regression analysis. The spatial predictive model combines data on the locations of the known dwelling sites, environmental factors and shore displacement data. The predictions were visualised into raster maps that show the predictions for inhabitance 3000 and 5000 years ago. The aim of these maps was to help archaeologists map potential spots for human activity. The produced landscape reconstructions clarified previous shore displacement studies of the Mätäjoki region and provided new information on the location of shoreline. From the shore displacement history of the Mätäjoki Valley arise the following stages: 1. The northernmost hills of the Mätäjoki Valley rose from Ancylus Lake approximately 10000 years ago. Shore displacement was fast during the following thousand years. 2. The area was an archipelago with a relatively steady shoreline 9000 7000 years ago. 8000 years ago the shoreline drew back in the middle and southern parts of the river valley because of the transgression of the Litorina Sea. 3. Mätäjoki was a sheltered bay of the Litorina Sea 6000 5000 years ago. The Vantaanjoki River started to flow into the Mätäjoki Valley approximately 5000 years ago. 4. The sediment plains in the southern part of the river valley rose from the sea rather quickly 5000 3000 years ago. Salt water still pushed its way into the southermost part of the valley 4000 years ago. 5. The shoreline proceeded to Pitäjänmäki rapids where it stayed at least a thousand years 3000 2000 years ago. The predictive models managed to predict the locations of dwelling sites moderately well. The most accurate predictions were found on the eastern shore and Malminkartano area. Of the environment variables sand and aspect of slope were found to have the best predictive power. From the results of this study we can conclude that the Mätäjoki Valley has been a favorable location to live especially 6000 5000 years ago when the climate was mild and vegetation lush. The laser point data set used here works best in shore displacement studies located in rural areas or if further specific palaeogeographic or hydrologic analysis in the research area is not needed.

A Training-Based Iterative Detection/Channel Estimation Scheme for Large Non-Orthogonal STBC MIMO Systems

In this paper, we propose a training-based channel estimation scheme for large non-orthogonal space-time block coded (STBC) MIMO systems.The proposed scheme employs a block transmission strategy where an N-t x N-t pilot matrix is sent (for training purposes) followed by several N-t x N-t square data STBC matrices, where Nt is the number of transmit antennas. At the receiver, we iterate between channel estimation (using an MMSE estimator) and detection (using a low-complexity likelihood ascent search (LAS) detector) till convergence or for a fixed number of iterations. Our simulation results show that excellent bit error rate and nearness-to-capacity performance are achieved by the proposed scheme at low complexities. The fact that we could show such good results for large STBCs (e.g., 16 x 16 STBC from cyclic division algebras) operating at spectral efficiencies in excess of 20 bps/Hz (even after accounting for the overheads meant for pilot-based channel estimation and turbo coding) establishes the effectiveness of the proposed scheme.

Hot gaseous coronae of early-type galaxies and their radio luminosity function

Recent X-ray observations have revealed that early-type galaxies (which usually produce extended double radio sources) generally have hot gaseous haloes extending up to approx102kpc1,2. Moreover, much of the cosmic X-ray background radiation is probably due to a hotter, but extremely tenuous, intergalactic medium (IGM)3. We have presented4–7 an analytical model for the propagation of relativistic beams from galactic nuclei, in which the beams' crossing of the pressure-matched interface between the IGM and the gaseous halo, plays an important role. The hotspots at the ends of the beams fade quickly when their advance becomes subsonic with respect to the IGM. This model has successfully predicted (for typical double radio sources) the observed8 current mean linear-size (approx2Dsime350 kpc)4,5, the observed8–11 decrease in linear-size with cosmological redshift4–6 and the slope of the linear-size versus radio luminosity10,12–14 relation6. We have also been able to predict the redshift-dependence of observed numbers and radio luminosities of giant radio galaxies7,15. Here, we extend this model to include the propagation of somewhat weaker beams. We show that the observed flattening of the local radio luminosity function (LRLF)16–20 for radio luminosity Papproximately 1024 W Hz-1 at 1 GHz can be explained without invoking ad hoc a corresponding break in the beam power function Phi(Lb), because the heads of the beams with Lb < 1025 W Hz-1 are decelerated to sonic velocity within the halo itself, which leads to a rapid decay of radio luminosity and a reduced contribution of these intrinsically weaker sources to the observed LRLF.

Prediction of Specimen Strain from Extensometer Deflection Measurements in a Direct Stress Fatigue Test Specimen under Static Tensile Loading

The displacement between the ridges situated outside the filleted test section of an axially loaded unnotched specimen is computed from the axial load and shape of the specimen and compared with extensometer deflection data obtained from experiments. The effect of prestrain on the extensometer deflection versus specimen strain curve has been studied experimentally and analytically. An analytical study shows that an increase in the slope of the stress-strain curve in the inelastic region increases the slope of the corresponding computed extensometer deflection versus specimen strain curve. A mathematical model has been developed which uses a modified length ¯ℓef in place of the actual length of the uniform diameter test section of the specimen. This model predicts the extensometer deflection within 5% of the corresponding experimental value. This method has been successfully used by the authors to evolve an iterative procedure for predicting the cyclic specimen strain in axial fatigue tests on unnotched specimens.

Design of Constant Accuracy Linear Proportional Weir

Five different shaped weirs were designed and pertinent data for their use are given. One of these weir shapes had the least “sharp edge” at the junction of the base weir and “complementary weir.” Two other types of weirs had equal slopes at the junction of the base weir and complementary weir. Another shape, for which neither the indication accuracy was constant nor the slope was equal at the junction of the base weir and complementary weir, was also tested. The results of the four weir shapes hydraulically tested give consistent values for the coefficient of discharge varying between 0.625 to 0.631. The indication accuracies of all the previously designed linear proportional weirs (includig Sutro weir) are neither constant nor unity, as is believed.

Effect of grain size and texture on the mechanical properties of warm worked cadmium-1.5 Pct zinc alloy

The structural changes occurring during warm working of Cd-1.5 pct Zn alloy and their effect on the subsequent mechanical properties are studied. It is observed that changes in grain size and preferred orientation are important to a large extent in controlling the mechanical strength. The Hall-Petch slope,R decreases in the warm worked material while the friction stress, σo increases. The lowerR values are attributed to the development of a (101l) texture and the higher σo values are interpreted on the basis of changes in the basal texture.

Theory of unitarity bounds and low-energy form factors

We present a general formalism for deriving bounds on the shape parameters of the weak and electromagnetic form factors using as input correlators calculated from perturbative QCD, and exploiting analyticity and unitarily. The values resulting from the symmetries of QCD at low energies or from lattice calculations at special points inside the analyticity domain can be included in an exact way. We write down the general solution of the corresponding Meiman problem for an arbitrary number of interior constraints and the integral equations that allow one to include the phase of the form factor along a part of the unitarity cut. A formalism that includes the phase and some information on the modulus along a part of the cut is also given. For illustration we present constraints on the slope and curvature of the K-l3 scalar form factor and discuss our findings in some detail. The techniques are useful for checking the consistency of various inputs and for controlling the parameterizations of the form factors entering precision predictions in flavor physics.

A note on transient photocurrents at semiconductor electrodes

The imprint of the changing surface concentration of minority carriers in photocurrent transients is marginalized in “switch off” transients as compared to “switch on” transients. When the surface level is situated close to either one of the band edges, it is shown that in principle it must be possible to obtain the energy of the surface level from “switch off” transients.The time constants for the “switch on” and “switch off” cases behave differently with potential. While in “switch off”, transient plots, the magnitude of the slope decreases monotonically with increasing band bending potentials; for the “switch on” however, though it decreases and is identical to “switch off” initially, beyond a certain increase in potential the magnitude of the slope shows an increase.

Effects of Parasitics and Interface Traps on Ballistic Nanowire FET in the Ultimate Quantum Capacitance Limit

In this paper, we focus on the performance of a nanowire field-effect transistor in the ultimate quantum capacitance limit (UQCL) (where only one subband is occupied) in the presence of interface traps (D-it), parasitic capacitance (C-L), and source/drain series resistance (R-s,R-d), using a ballistic transport model and compare the performance with its classical capacitance limit (CCL) counterpart. We discuss four different aspects relevant to the present scenario, namely: 1) gate capacitance; 2) drain-current saturation; 3) subthreshold slope; and 4) scaling performance. To gain physical insights into these effects, we also develop a set of semianalytical equations. The key observations are as follows: 1) A strongly energy-quantized nanowire shows nonmonotonic multiple-peak C-V characteristics due to discrete contributions from individual subbands; 2) the ballistic drain current saturates better in the UQCL than in the CCL, both in the presence and absence of D-it and R-s,R-d; 3) the subthreshold slope does not suffer any relative degradation in the UQCL compared to the CCL, even with Dit and R-s,R-d; 4) the UQCL scaling outperforms the CCL in the ideal condition; and 5) the UQCL scaling is more immune to R-s,R-d, but the presence of D-it and C-L significantly degrades the scaling advantages in the UQCL.

Effect of stacking fault energy on the dynamic recrystallization during hot working of FCC metals: A study using processing maps

The influence of stacking fault energy (SFE) on the mechanism of dynamic recrystallization (DRX) during hot deformation of FCC metals is examined in the light of results from the power dissipation maps. The DRX domain for high SFE metals like Al and Ni occurred at homologous temperature below 0·7 and strain rates of 0·001 s−1 while for low SFE metals like Cu and Pb the corresponding values are higher than 0·8 and 100 s−1. The peak efficiencies of power dissipation are 50% and below 40% respectively. A simple model which considers the rate of interface formation (nucleation) involving dislocation generation and simultaneous recovery and the rate of interface migration (growth) occurring with the reduction in interface energy as the driving force, has been proposed to account for the effect of SFE on DRX. The calculations reveal that in high SFE metals, interface migration controls DRX while the interface formation is the controlling factor in low SFE metals. In the latter case, the occurrence of flow softening and oscillations could be accounted for by this model.

Temperature response of trehalase from a mesophilic (Neurospora crassa) and a thermophilic (Thermomyces lanuginosus) fungus

The purified trehalases of the mesophilic fungus, Neurospora crassa, and the thermophilic fungus, Thermomyces lanuginosus, had similar temperature and pH optima for activity, but differed in molecular weight, electrophoretic mobility and Michaelis constant. At lower concentration, trehalases from both fungi were inactivated to similar extent at 60°C. While purified trehalase of T. lanuginosus was afforded protection against heat-inactivation by proteinaceous protective factor(s) present in mycelial extracts, by bovine serum albumin and by casein, these did not afford protection to N. crassa trehalase against heat inactivation. Both trehalases exhibited discontinuous Arrhenius plots with temperature of discontinuity at 40°C. The activation energy calculated from the slope of the Arrhenius plot was higher for the T. lanuginosus enzyme. The plots of apparent K m versus 1/T for trehalases of N. crassa and T. lanuginosus were linear from 30° to 60°C. The results show that purified trehalases of the mesophilic and the thermophilic fungus are distinct. Although, these exhibit similar thermostability of their catalytic function at low concentration, distinctive thermal stability characteristics of thermophilic enzyme become apparent at high protein concentration. This could be brought about in the cell by the enzyme itself, or by other proteins.

Flocculation, filtration and selective flocculation studies on haematite ore fines using starch

The flocculation and filtration characteristics of typical Indian iron ore fines have been studied using starch as flocculant in the presence of an inorganic electrolyte, namely calcium chloride. The effect of various parameters such as pH, starch and calcium chloride concentrations and pulp density on the settling and filtration rates, turbidity of the supernatant and on residual starch and calcium ion concentrates has been investigated through a statistical design and analysis approach and subsequently optimised on a laboratory scale. The adsorption mechanisms of starch onto haematite have been elucidated through adsorption density measurements, infrared and X-ray photoelectron spectroscopic techniques. The rheological property of the polymer solutions of relevance to flocculations has also been investigated. Further, the role of metal ion-starch interactions in the bulk solution, has been studied. In order to understand the nature of polymer adsorption at the double-layer, electrokinetic studies have been carried out with the iron ore mineral samples using starch and calcium chloride. Based on the above findings, selective floculaation tests on artificial mixtures of iron ore minerals have been carried out to determine the separation efficiencies from the view point of alumina and silica removal from haematite as well as the control of alumina: silica ratio in Indian iron ores.

A Rapid Bioassay for Measuring Inhibin Activity

A sensitive and rapid bioassay of inhibin is described. Swiss albino female mice, 27 days old, weighing 25-30 g, were primed with 20 IU hCG, given in 2 equal doses, administered at 0900 h and 1800 h. An increment of 200% in uterine weight could be observed when the animals were autopsied the next day at 1000 h. The validity of the endpoint chosen, as a function dependent on FSH, was shown by the fact that neutralization of endogenous FSH by FSH antiserum led to an inhibition of uterine weight increase. Further injection of the inhibin material caused an actual reduction in the heightened levels of FSH (ng/ml) brought about by hCG: Control, 207 ± 13.6; hCG, 365 ± 28.8 and hCG inhibin, below the detection level of radioimmunoassay. Inhibin preparation from ovine testicular extract when tested at 3 dose levels showed a dose dependent and significant suppression in uterine weight increase. The assay was statistically validε = 2.5; slope = 23.9; λ = 0.104 and intra- and interassay variation = 8.3% and 11.7%, respectively. Since the mouse uterine weight assay is specific, has greater sensitivity and is uniformly reproducible, it is suggested that this assay procedure is ideally suited to assess the activity of different inhibin test preparations as well as to follow the purification of inhibin activity from crude material.