Non-uniform Rate Research Articles

Low Complexity BICM MIMO OFDM Demodulator

In this paper, we consider low-complexity detection of coded spatial data streams with uniform power and non-uniform rate distribution in a single-user MIMO system. The receiver decodes these different streams as if facing a multiple access channel (MAC). Conventional receiver solutions for such schemes are based on successive interference cancellation (SIC) by employing a linear minimum mean square error (MMSE) successive stripping detector, where the optimality is nonetheless constrained to Gaussian codebooks. As a remedy, this paper introduces a novel near-optimal low-complexity max-log-MAP demodulator for a $2\times n_{r}$ system ( $n_{r}$ is the number of receive antennas) which reduces the complexity of detection from ${\cal O}(\vert\chi\vert^{2})$ to ${\cal O}(\vert\chi\vert^{1})$ , where $\vert\chi\vert$ indicates the size of the signal set. In the sequel, we extend the proposed low-complexity demodulation scheme to higher-dimensional MIMO systems via a hybrid detector, where significant complexity saving is realized at the expense of slight performance degradation.

Failure of steady-state thermodynamics in nonuniform driven lattice gases.

To be useful, steady-state thermodynamics (SST) must be self-consistent and have predictive value. Consistency of SST was recently verified for driven lattice gases under global weak exchange. Here I verify consistency of SST under local (pointwise) exchange, but only in the limit of a vanishing exchange rate; for a finite exchange rate the coexisting systems have different chemical potentials. I consider the lattice gas with nearest-neighbor exclusion on the square lattice, with nearest-neighbor hopping, and with hopping to both nearest and next-nearest neighbors. I show that SST does not predict the coexisting densities under a nonuniform drive or in the presence of a nonuniform density provoked by a hard wall or nonuniform transition rates. The steady-state chemical potential profile is, moreover, nonuniform at coexistence, contrary to the basic principles of thermodynamics. Finally, I discuss examples of a pair of systems possessing identical steady states but which do not coexist when placed in contact. The results of these studies confirm the validity of SST for coexistence between spatially uniform systems but cast serious doubt on its consistency and predictive value in systems with a finite rate of particle exchange between coexisting regions exhibiting a nonuniform particle density.

Asymmetrical degradation behaviors in amorphous InGaZnO thin-film transistors under various gate and drain bias stresses

The asymmetrical degradation behaviors of amorphous indium–gallium–zinc oxide thin-film transistors are studied comprehensively under various gate and drain bias stresses. The transfer curve moves to the negative direction after bias stresses are applied, and different types of asymmetrical degradation are observed depending upon the magnitude of the applied gate and drain bias stresses. After the application of gate-to-source (VGS) and drain-to-source (VDS) bias stresses of (VGS = 16 V, VDS = 16 V) and (VGS = 22 V, VDS = 10 V), the forward mode transfer curve exhibits a more negative shift compared to that of the reverse mode, whereas opposite results are observed under the stress condition of (VGS = 10 V, VDS = 25 V). From the two-dimensional simulation results and the separately extracted subgap density of states in the source and drain sides of the thin film transistors before and after the application of various bias stresses, the local high electric field-induced nonuniform generation rate of the subgap states near the conduction band edge is considered to be the dominant mechanism causing the asymmetrical degradation of the devices under various gate and drain bias stresses. The generation of the subgap states is observed at different locations depending upon the magnitude of the applied gate and drain bias stresses.

An Integrated Approach Reveals Regulatory Controls on Bacterial Translation Elongation

Ribosomes elongate at a nonuniform rate during translation. Theoretical models and experiments disagree on the invivo determinants of elongation rate and the mechanism by which elongation rate affects protein levels. To resolve this conflict, we measured transcriptome-wide ribosome occupancy under multiple conditions and used it to formulate a whole-cell model of translation in E.coli. Our model predicts that elongation rates at most codons during nutrient-rich growth are not limited by the intracellular concentrations of aminoacyl-tRNAs. However, elongation pausing during starvation for single amino acids is highly sensitive to the kinetics of tRNA aminoacylation. We further show that translation abortion upon pausing accounts for the observed ribosome occupancy along mRNAs during starvation. Abortion reduces global protein synthesis, but it enhances the translation of a subset of mRNAs. These results suggest a regulatory role for aminoacylation and abortion during stress, and our study provides an experimentally constrained framework for modeling translation.

Design of Energy-Saving Control Software Algorithms in Large Industrial Network

In the operation process of large industrial control network, with conventional fuzzy PID control algorithm for industrial control networks energy-saving control, excessive industrial networks will aggravate machine wear of the single network, thereby reduce the effect of energy-saving for industrial network. This paper presents an approach for industrial network energy-saving control based on non-uniform data production rate. According to the relationship between the network load and loss, the loss model of industrial control network can be established. Adaptive linear genetic method is utilized to control industrial control network energy-saving load, so as to achieve energy-saving control of industrial control network. Experimental results show that the algorithm can effectively improve the energy-saving efficiency of industrial control network, and achieve satisfactory results.

Threshold Chloride Levels for Localized Carbon Steel Corrosion in Simulated Concrete Pore Solutions Using Coupled Multielectrode Array Sensors

Threshold chloride levels for localized corrosion of carbon steel material have been studied in three types of simulated concrete pore solutions: sodium hydroxide-potassium hydroxide (NaOH-KOH) with pH 11.6, calcium hydroxide (Ca[OH]2) with pH 12.6, and sodium hydroxide-potassium hydroxide-calcium hydroxide (NaOH-KOH-Ca[OH]2) with pH 13.3. The nonuniform corrosion rates of carbon steel were measured with coupled multielectrode array sensors (CMAS) when the chloride concentration was changed from 0.0005 mol/L to 1 mol/L in each solution. Open-circuit potentials were also measured from the coupling joint of the CMAS probes and electrodes made of rebar specimens immersed in the simulated pore solutions to verify the results from the CMAS probes.

Crystallization rate control for alkali halide crystal growth by the VGF technique with a skull layer

This study describes the ability to use the melt‐level control for stabilization of the crystallization rate during NaI crystal growth by the VGF technique with a skull layer. It is shown that a conventional linear decrease of the heater temperature leads to a nonuniform crystallization rate and deterioration of crystal quality. A method and algorithm of temperature control for the stabilization of the crystallization rate during crystal growth is proposed. The series of growth experiments with NaI(Tl) crystals proved the efficiency of this approach and ability to obtain scintillators with high registration efficiency, about 6.3% energy resolution for a 137Cs (662 keV) source.

A novel thermal dispersion model to improve prediction of nanofluid convective heat transfer

This study numerically investigates the hydrothermal characteristics of the nanofluid in a laminar flow inside a straight tube. A new model is proposed for dispersion thermal conductivity while a theoretical approach is adopted to predict the particle distribution at the tube cross section considering the effects of non-uniform shear rate, Brownian diffusion and viscosity gradient on particle migration. It is observed that nanoparticles are not distributed uniformly at the tube cross section such that the values of concentration are higher at central regions of the tube and this non-uniformity intensifies at higher mean concentrations and Reynolds numbers. The particle distribution is applied in the proposed dispersion model. The findings show that this dispersion model presents more accurate results than traditional homogenous one. For dispersion model, the velocity profile is flatter than that obtained from the homogenous model. In addition, in the vicinity of the wall, the value of temperature and its gradient obtained from the dispersion model are respectively lower and higher than those from the homogenous model. Increasing the mean concentration results in convective heat transfer enhancement, while causing not much penalty in pressure drop. This indicates that application of nanofluids can result in energy efficiency improvement.

Rumor Propagation Model for Complex Network with Non-Uniform Propagation Rates

Considering propagation characteristics and affecting factors of rumor in real-world complex networks, this paper described different propagation rates of different nodes by introducing the rumor acceptability function. Based on mean-field theory, this paper presented a rumor propagation model with non-uniform propagation rate, and then simulated the behaviour of rumor propagation on scale-free network and calculated the propagation thresholds by corresponding dynamics equation. Theoretical analysis and simulation results show that nodes with different rumor acceptability could lead to slowing the spread of rumors, make positive propagation threshold arise, and effectively contain the outbreak and reduce the risk of rumors.

Fusion Estimation for Sensor Networks With Nonuniform Estimation Rates

This paper investigates the multi-sensor fusion estimation problem for wireless sensor networks with nonuniform estimation rates. First, each sensor generates local estimates with two rates, namely, a fast rate and a slow rate according to its power situation, where the estimation rates among the sensors are allowed to be different from each other. Second, a fusion rule with matrix weights is designed for each sensor to fuse available local estimates generated at different time scales, and a set of recursive equations are presented to compute estimation error cross-covariances. The fusion algorithm is applicable to both cases where the measurement noises are mutually correlated and are uncorrelated, and is also applicable to the case where the sensors are not time-synchronized. Two types of estimators are designed according to different considerations of design complexity and computation costs, and convergence analysis for the type II estimators is also presented. Finally, two illustrative examples are given to demonstrate the effectiveness of the proposed estimators.

후방 감시 차량용 레이다를 이용한 ISAR 영상 형성

Abstract This paper introduces the inverse synthetic aperture radar(ISAR) imaging technique for rear view target of an automobile, which uses both linear frequency modulation-frequency shift keying(LFM-FSK) waveform and monopulse tracking. LFM-FSK waveform consists of two sequential stepped frequency waveforms with some frequency offset, and thus, can be used to generate ISAR images of rear view target of an automobile . However, ISAR images can often be blurred due to non-uniform change rate of relative aspect angle between radar and target. In order to address this problem, one-dimensional(1-D) Lagrange inter-polation technique in conjunction with angle information obtained from the monopulse tracking is applied to generate uniform data across the radar’s aspect angle. Simulation results show that the proposed method can provide focused ISAR images. Key words: ISAR, LFM-FSK Waveform, Automotive Radar o;p qrs htuvQY>wxWy_(‘ITz{|}~* x’(;p<h:c€(NIPA-2013-H0203-13-1001).‚ ƒ„ h@tGH th(Department of Electrical Engineering, Pohang University of Science and Technology) Manuscript received November 7, 2013 ; Revised December 3, 2013 ; Accepted December 4, 2013. (ID No. 20131107-111)Corresponding Author: Kyung-Tae Kim (e-mail: kkt@postech.ac.kr)

Terrestrial carbon cycle affected by non-uniform climate warming

Feedbacks between the terrestrial carbon cycle and climate change could affect many ecosystem functions and services. A synthesis of global air temperature data reveals non-uniform rates of climate warming on diurnal and seasonal timescales, and heterogeneous impacts on ecosystem carbon cycling.

Non-homogeneous SiGe-on-insulator formed by germanium condensation process

Ge condensation process of a sandwiched structure of Si/SiGe/Si on silicon-on-insulator (SOI) to form SiGe-on-insulator (SGOI) substrate is investigated. The non-homogeneity of SiGe on insulator is observed after a long time oxidation and annealing due to an increased consumption of silicon at the inflection points of the corrugated SiGe film morphology, which happens in the case of the rough surface morphology, with lateral Si atoms diffusing to the inflection points of the corrugated SiGe film. The transmission electron microscopy measurements show that the non-homogeneous SiGe layer exhibits a single crystalline nature with perfect atom lattice. Possible formation mechanism of the non-homogeneity SiGe layer is presented by discussing the highly nonuniform oxidation rate that is spatially dependent in the Ge condensation process. The results are of guiding significance for fabricating the SGOI by Ge condensation process.

A gaas phononic crystal with shallow noncylindrical holes

A square lattice of shallow, noncylindrical holes in GaAs is shown to act as a phononic crystal (PnC) reflector. The holes are produced by wet-etching a GaAs substrate using a citric acid:H2O2 etching procedure and a photolithographed array pattern. Although nonuniform and asymmetric etch rates limit the depth and shape of the phononic crystal holes, the matrix acts as a PnC, as demonstrated by insertion loss measurements together with interferometric imaging of surface acoustic waves propagating on the GaAs surface. The measured vertical displacement induced by surface phonons compares favorably with finite-difference time-domain simulations of a PnC with rounded-square holes.

Effects of parameters on performance of high temperature molten salt latent heat storage unit

In order to investigate the performance of high temperature molten salt latent heat storage (LHS) unit under variable conditions, the effects of heat transfer fluid (HTF) inlet temperature, velocity and tube geometric parameters on melting time, melting fraction, heat storage rate and solid–liquid interface were numerically investigated. The results show that within the studied parameters, the HTF inlet temperature has the largest effect on LHS rate. With the HTF inlet temperature increasing from 1070 K to 1110 K, the melting time reduces 53.0%. However, the larger inlet temperature will result in more non-uniform melting rate and solid–liquid interface distribution. The second important influential factor is the HTF inlet velocity. When inlet velocity increases from 10 m/s to 20 m/s, the melting time reduces 45.4%. And the effect of velocity on the solid–liquid interface distribution is uniform. LHS tube diameter has the lowest effect on performance. With outer tube radius increasing from 24.0 mm to 28.0 mm, the melting time only augments 16.3% and the solid–liquid interface distribution becomes more uniform. In a general conclusion, when the heat load of the heat source is larger, a larger HTF mass flow rate is suitable to maintain a moderate HTF temperature. And then for the LHS unit, a larger tube diameter is recommendable.

Rotating elegant bessel-gaussian beams

We considered a new three-parameter family of rotating asymmetric Bessel-Gaussian beams (aBG-beams) with integer and fractional orbital angular momentum (OAM). Complex amplitude of aBG-beams is proportional to a Gaussian function and to n-th order Bessel function with complex argument. These beams have finite energy. The asymmetry ratio of the aBG-beam depends on the real parameter c ≥ 0. For c = 0, the aBG-beam coincides with the conventional radially symmetric Bessel-Gaussian beam, with increasing c intensity distribution of the aBG-beam takes the form of Crescent. At c &gt;&gt; 1, the beam is widening along the vertical axis while shifting along the horizontal axis. In initial plane, the intensity distribution of asymmetric Bessel-Gaussian beams has a countable number of isolated zeros located on the horizontal axis. Locations of these zeros correspond to optical vortices with unit topological charges and opposite signs on different sides of the origin. During the beam propagation, centers of these vortices rotate around the optical axis along with the entire beam at a non-uniform rate (for large c &gt;&gt; 1): they will rotate by 45 degrees at a distance of the Rayleigh range, and then by another 45 degrees during the rest distance. For different values of the parameter c zeros in the transverse intensity distribution of the beam change their location and change the OAM of the beam. Isolated intensity zero on the optical axis corresponds to an optical vortex with topological charge of n. Laser beam with the shape of rotating Crescent has been generated by using a spatial light modulator.

Development of an ultrasound image processing approach to enable automated needle localisation for epidural anesthesia

In this paper, ultrasound imaging is utilised to detect the anatomical structure of lumbar spine, in order to automatically search for a proper epidural needle insertion site. Induced by random speckle noise, ultrasound images are generally obscure and have low resolution, which decrease the readability of the image content. In order to improve the interpretability of ultrasound images, local normalisation modified with difference of Gaussian (DoG) algorithm is used for pre-processing. The pre-processing procedure successfully filters the noise and extracts the main anatomical structures; meanwhile it removes the local means induced by non-uniform wave reflection rate. Then, template matching algorithm, augmented with a position correlator, is utilised to automatically identify the features of interest. Based on the result of feature matching, proper needle insertion site will be identified automatically. The approach has been tested on more than 200 ultrasound images with a 100% success rate. The proposed system allows the anesthetist to use the approach efficiently without the burden of interpreting real time ultrasound images.

Modelling and Simulation for Rumour Propagation on Scale-Free Network with Non-Uniform Propagation Rates

Considering propagation characteristics and affecting factors of rumour in real-world complex networks, this paper describes different propagation rates of different nodes by introducing the rumour acceptability function. Based on mean-field theory, this paper presents a rumour propagation model on scale-free network with non-uniform propagation rate and then simulates the behaviour of rumour propagation on scale-free network and calculates the propagation thresholds by corresponding dynamics equation. Theoretical analysis and simulation results show that nodes with different rumour acceptability could lead to slowing the spread of rumours, make positive propagation threshold arise, and effectively contain the outbreak and reduce the risk of rumours.

Health, fairness and taxation

We consider a model where agents differ in their preferences about consumption labor and health, in their (health-dependent) earning ability, and in their health disposition. We study the joint taxation of income and health expenditure, under incentive-compatibility constraints, on the basis of efficiency and fairness principles. The fairness principles we consider propose, on one side, to reduce inequalities deriving from factors that do not depend on individuals’ responsibility. On the other side, redistribution should be precluded at least when all agents in the economy have equal physical characteristics. We construct, on the basis of such principles, a particular social welfare function. Then we give the explicit formula for the comparison of tax policies: we prove that a tax reform should always benefit agents with the worst earning ability and the worst health disposition first. Finally, in some cases, at the bottom of the income distribution the optimal tax scheme should exhibit non-uniform tax rates over health expenditure and non-positive average marginal tax rates over income.

Particle migration in nanofluids considering thermophoresis and its effect on convective heat transfer

The effects of particle migration on concentration distribution and convective heat transfer coefficient of the water-TiO2 nanofluid were investigated inside a circular tube. The concentration distribution was obtained considering thermophoresis, non-uniform shear rate, Brownian diffusion and viscosity gradient. Using the scale analysis, it was demonstrated that thermophoresis can have a significant effect on the particle migration. Dispersion approach was used for simulation, while a non-uniform concentration was applied. An experimental study was conducted to examine the numerical solution accuracy and there was a good agreement between the experimental and numerical results. Non-uniformity of the concentration is intensified by increasing the Reynolds number and the particle size. Thermophoresis makes the concentration more non-uniform and the velocity profile flatter as well. At greater mean concentrations, the effect of thermophoresis on particle distribution and convective heat transfer coefficient is highlighted. Meanwhile, considering thermophoresis yields greater convective heat transfer coefficient in all Reynolds numbers.