Second-order Power Research Articles

Second-order power control with asymptotically fast convergence

This paper proposes a distributed power control algorithm that uses power levels of both current and previous iterations for power update. The algorithm is developed by applying the successive overrelaxation method to the power control problem. The gain from such a second-order algorithm is in faster convergence. Convergence analysis of the algorithm in case of feasible systems is provided in this paper. Using the distributed constrained power control (DCPC) as a reference algorithm, we carried out computational experiments on a DS-CDMA system. The results indicate that our algorithm significantly enhances the convergence speed of power control. A practical version of the proposed algorithm is provided and compared with the bang-bang type algorithm used in the IS-95 and the WCDMA systems. The results show that our algorithm also has a high potential for increasing the radio network capacity. Our analysis assumes that the system is feasible in the sense that we can support every active user by an optimal power control. When the system becomes infeasible because of high traffic load, it calls for other actions such as transmitter removal, which is beyond the scope of the present paper.

On the Characteristic Function of the Joint Limit Distribution of the First- and Second-Order Power Sums

In this paper we investigate the joint limit characteristic function of normalized first and second-order power sums for a sequence of i.i.d. random variables with distributions belonging to the domain of attraction of an $\ap$-stable law for $\ap < 2$. An explicit form is presented in terms of generalized hypergeometric functions when $0 < \ap < 2$, $\ap\neq 1$, and that of Fresnel functions S and C for $\ap=1$.

Comparison of LR, Score, and Wald Tests in a Non-IID Setting

Considering a large class of tests, we study higher order power in a possibly non-iid set-up. Optimum properties for the likelihood ratio and score tests are exhibited under the criteria of second-order local maximinity and third-order local average power, respectively. The issue of stringency with regard to third-order average power has been addressed. We also compare the power properties of various Bartlett-type adjustments for the tests.

Electrical characterization of semi-insulating metalorganic vapor phase epitaxy GaAs grown by controlled oxygen incorporation

Semi-insulating GaAs layers were produced by low pressure metalorganic vapor phase epitaxy (MOVPE) through the intentional incorporation of oxygen. A commercially available oxygen precursor, diethyl aluminum ethoxide (DEALO, (C 2H 5) 2AlOC 2H 5), was used as the oxygen source. Bulk resistivity of the oxygen-doped GaAs (GaAs:O) was determined by current-voltage ( I-V) measurement on n-i-n mesa structure. Resistivities greater than 6 X 10 9 Ω cm at 297.5 K have been achieved. Constant capacitance values obtained from steady state capacitance-voltage ( C-V) measurements on the n-i-n structure indicate a very low net free carrier concentration in GaAs:O. Activation energy deduced from temperature-dependent resistivity measurement was found to be concentration-dependent. A second-order power law dependence of resistivity on DEALO mole fraction was observed. These observations coincide with the highly non-linear oxygen incorporation behavior using DEALO as the oxygen precursor.

Second-order power spectrum and nonlinear evolution at high redshift

view Abstract Citations (243) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Second-Order Power Spectrum and Nonlinear Evolution at High Redshift Jain, Bhuvnesh ; Bertschinger, Edmund Abstract The Eulerian cosmological fluid equations are used to study the nonlinear mode coupling of density fluctuations. We evaluate the second-order power spectrum including all four-point contributions. In the weakly nonlinear regime we find that the dominant nonlinear contribution for realistic cosmological spectra is made by the coupling of long-wave modes and is well estimated by second order perturbation theory. For a linear spectrum like that of the cold dark matter model, second order effects cause a significant enhancement of the high $k$ part of the spectrum and a slight suppression at low $k$ near the peak of the spectrum. Our perturbative results agree well in the quasilinear regime with the nonlinear spectrum from high-resolution N-body simulations. We find that due to the long-wave mode coupling, characteristic nonlinear masses grow less slowly in time (i.e., are larger at higher redshifts) than would be estimated using the linear power spectrum. For the cold dark matter model at $(1+z)=(20,10,5,2)$ the nonlinear mass is about $(180,8,2.5,1.6)$ times (respectively) larger than a linear extrapolation would indicate, if the condition rms $\delta\rho/\rho =1$ is used to define the nonlinear scale. At high redshift the Press-Schechter mass distribution significantly underestimates the abundance of high-mass objects for the cold dark matter model. Although the quantitative results depend on the definition of the nonlinear scale, these basic consequences hold for any initial spectrum whose post-recombination spectral index $n$ decreases sufficiently rapidly with increasing $k$, a feature which arises quite generally during the transition from a radiation- to matter-dominated universe. Publication: The Astrophysical Journal Pub Date: August 1994 DOI: 10.1086/174502 arXiv: arXiv:astro-ph/9311070 Bibcode: 1994ApJ...431..495J Keywords: Dark Matter; Galactic Clusters; Galactic Evolution; Mass Distribution; Power Spectra; Red Shift; Astronomical Models; Cosmology; Coupling; Galactic Mass; Many Body Problem; Perturbation Theory; Relativity; Space Density; Space-Time Functions; Astrophysics; COSMOLOGY: THEORY; COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE; GALAXIES: CLUSTERING; GALAXIES: FORMATION; Astrophysics E-Print: 25 pages, AAS Latex v3.0, figures and postscript available by anonymous ftp to arcturus.mit.edu, submittted to ApJ, preprint IAS-AST-93/70 and MIT-CSR-93-32 full text sources arXiv | ADS |

Kinetics of toluene alkylation with methanol over magnesium-modified ZSM-5

The kinetics of toluene alkylation with methanol has been studied over both unmodified and Mg-modified ZSM-5 catalysts. On the basis of the product distribution obtained over the unmodified zeolite, the following secondary reactions have been considered: methanol dehydration, toluene disproportionation and xylene dealkylation. Power law and Langmuir-Hinshelwood-Hougen-Watson (LHHW) models have been tested for the main toluene alkylation reaction, the best fits to the experimental data being achieved with two models: a second-order power law model and a model based on the Rideal-like mechanism. The first one has been applied to the results obtained with the Mg-modified catalyst, including the effect of the diffusion rate, due to its simpler expression. Over this catalyst p-xylene is the only isomer present in the primary product, hence m- and o-xylene formation takes place by p-xylene isomerization on the external surface catalytic sites. Therefore, the kinetic model developed for the Mg-modified zeolite takes into account, as well as diffusional effects, the influence of p-xylene isomerization over the external zeolite surface, reproducing the experimental product distribution with an average relative error of 6.8%

Second-order power corrections in the heavy-quark effective theory. I. Formalism and meson form factors.

In the heavy-quark effective theory, hadronic matrix elements of currents between two hadrons containing a heavy quark are expanded in inverse powers of the heavy-quark masses, with coefficients that are functions of the kinematic variable $v\ifmmode\cdot\else\textperiodcentered\fi{}{v}^{\ensuremath{'}}$. For the ground-state pseudoscalar and vector mesons, this expansion is constructed at order $\frac{1}{{m}_{Q}^{2}}$. A minimal set of universal form factors is defined in terms of matrix elements of higher-dimensional operators in the effective theory. The zero recoil normalization conditions following from vector current conservation are derived. Several phenomenological applications of the general results are discussed in detail. It is argued that at zero recoil the semileptonic decay rates for $B\ensuremath{\rightarrow}D\ensuremath{\ell}\ensuremath{\nu}$ and $B\ensuremath{\rightarrow}{D}^{*}\ensuremath{\ell}\ensuremath{\nu}$ receive only small second-order corrections, which are unlikely to exceed the level of a few percent. This supports the usefulness of the heavy-quark expansion for a reliable determination of ${V}_{\mathrm{cb}}$.g

Second-order power corrections in the heavy-quark effective theory. II. Baryon form factors.

The analysis of $1/m_Q^2$ corrections of the previous paper is extended to the semileptonic decays of heavy baryons. We focus on the simplest case, the ground state $\Lambda_Q$ baryons, in which the light degrees of freedom are in a state of zero total angular momentum. The formalism, while identical in spirit, is considerably less cumbersome than for heavy mesons. The general results are applied to the semileptonic decay $\Lambda_b\to\Lambda_c\,\ell\,\nu$. An estimate of the leading power corrections to the decay rate at zero recoil, which are of order $1/m_Q^2$, is presented. It is pointed out that a measurement of certain asymmetry parameters would provide a direct measurement of $1/m_Q^2$ corrections. Finally, it is shown how the analysis could be extended to include excited heavy baryons such as the $\Sigma_Q$ and the $\Sigma_Q^*$.

Laser remote sensing of aquatic environment: first- and second-order scattering model

Transport of a small divergent (of several millirads) laser beam in shallow waters has been investigated. A simple model was developed to describe and calculate the first- and second-order power and energy flux. From evaluation of the truncation error the applicability of the second-order approach for clear waters is concluded. On the other hand, turbid waters can be treated by introducing an effective beam attenuation coefficient. The computations were performed for different geometrical configurations of a lidar system and for diverse aquatic conditions. Finally, an alternative method for remote sensing of the concentration of particulate material by an airborne lidar instrument is proposed by using off-axis detection.

Functions, roles and form in international politics

The paper contributes towards a better understanding of geographical levels in international politics. After a theoretical introduction, in which different approaches to the definition of geographical levels are compared, attention is focused on the functions of the regional level in the global political system. To this end the paper first discusses the work of the geographer Saul B. Cohen, and sets Cohen's views against those of a few other authors in the field. Some empirical data are introduced with regard to the assumed functions of geopolitical regions and the role of second-order power centers in channelling organized violence and warfare. The form of the groupings proposed by Cohen is roughly compared with the results of recent analyses of post-war patterns of trade and institutional links. Some major differences with Cohen's regions are apparent, and patterns for different policy areas do not always coincide. Judging from the available empirical data. there is no clear development towards a more salient role of regional power

Comparison of tests in the multiparameter case I. Second-order power

In a multiparameter setting, considering a very large class of tests it is seen that under contiguous alternatives, unlike in the one-parameter case, identity of power up to the first order may not imply that up to the second order. It is, therefore, possible to discriminate among tests in terms of their second-order power in a multiparameter set-up. An explicit and easily applicable formula for second-order power difference has been obtained. It is also seen that identity of power up to the first order implies identity of “average” power up to the second order. The use of a new kind of polynomials, analogous to Hermite polynomials, is helpful in the derivation of the results.

Spectral analysis of quantization noise in a single-loop sigma-delta modulator with DC input

An exact discrete-time analysis of the moments and spectra of the quantization noise of a discrete-time single-loop sigma-delta modulator with a DC input is presented. An exact difference equation for the discrete-time nonlinear system is used to evaluate the first- and second-order moments and power spectrum of the binary quantizer noise and the binary quantizer output for a single-loop sigma-delta encoder with a DC input. It is shown that the sample mean and power of the binary quantization noise are consistent with the common uniform distribution assumption, but that the autocorrelation and power spectrum are not consistent with the white noise assumption. The results are used to evaluate the overall sample average mean squared quantization error as a function of the decimation filter used. >

Evaluation of power flow techniques for personal computers

An evaluation study is presented for running power flow programs on an IBM/AT personal computer (PC). Different issues that have been the subject of discussion for the mainframe computer implementation are addressed regarding the PC applications. These include convergence rates, iteration counts, memory requirements, effects of low precision arithmetic, ill conditioning, and the CPU times. A number of formulations of the power flow problem are considered and compared with regard to the mentioned issues. The investigated formulations are: the full Newton-Raphson power flow, the fast decoupled power flow, the Gauss-Seidel flow, and the second-order power flow using cartesian coordinates. The numerical results of running power flow studies for the IEEE 5, 14, 30, 57 and 118 bus test systems are presented and discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Evaluation of Power Flow Techniques for Personal Computers

An evaluation study is presented for running power flow programs on an IBM/AT personal computer (PC). Different issues that have been the subject of discussion for the mainframe computer implementation are addressed regarding the PC applications. These include convergence rates, iteration counts, memory requirements, effects of low precision arithmetic, ill conditioning, and the CPU times. A number of formulations of the power flow problem are considered and compared with regard to the mentioned issues. The investigated formulations are: the full Newton-Raphson power flow, the fast decoupled power flow, the Gauss-Seidel flow, and the second-order power flow using cartesian coordinates. The numerical results of running power flow studies for the IEEE 5, 14, 30, 57 and 118 bus test systems are presented and discussed. >

Construction of improved Lyapunov functions and extension of transient stability regions for power systems

In this paper different second-order power system models taking into account the effects of damping and transient saliency have been considered, and Lyapunov functions containing higher-order terms of the state variables have been constructed via the operational transform technique (OTT). Transient stability regions computed for different system damping conditions using Lyapunov functions generated by OTT, the trial and error method, the generalized Zubov method, Szego's procedure, the Popov method and the Lagrange-Charpit method are presented for comparison. The stability regions determined by OTT are better than those of the other methods.

Statistics of Rayleigh Backscatter From a Single-Mode Fiber

This paper contains a detailed analysis of the statistical properties of the Rayleigh backscatter signal from a single-mode optical fiber. Derivations of the first- and second-order statistics, autocorrelation function, and power spectral density of the backscatter wave are given. The probability density functions of the amplitude and intensity of the backscatter signal are also calculated.

Measurement of oceanic wind speed from HF sea scatter by skywave radar

Remote measurements of the spatial mean ocean wind speeds were obtained using Doppler spectra resolved to 0.08 Hz from high-resolution HF skywave-radar backscatter measurements of the ocean surface. A standard deviation of 2.4 m/s resulted from the correlation of observed winds over the ocean and the broadening of the Doppler spectra in the vicinity of the higher first-order Bragg line. This broadening, for Doppler spectra unperturbed by the ionospheric propagation, is proportional to the increase in power caused by higher order hydrodynamic and electromagnetic effects in the vicinity of the Bragg line and inversely proportional to the square root of the radio frequency. A lower bound on the measure of wind speed was established at 5 m/s by the low resolution spectral processing and low second-order power. An upper limit is suggested by the steep slope in the region of the sea backscatter spectrum outside the square root of two times the first-order Bragg line Doppler.

Measurement of oceanic wind speed from HF sea scatter by skywave radar

Remote measurements of the spatial mean ocean wind speeds were obtained using Doppler spectra resolved to 0.08 Hz from high-resolution HF skywave-radar backscatter measurements of the ocean surface. A standard deviation of 2.4 m/s resulted from the correlation of observed winds over the ocean and the broadening of the Doppler spectra in the vicinity of the higher first-order Bragg line. This broadening, for Doppler spectra unperturbed by the ionospheric propagation, is proportional to the increase in power caused by higher order hydrodynamic and electromagnetic effects in the vicinity of the Bragg line and inversely proportional to the square root of the radio frequency. A lower bound on the measure of wind speed was established at 5 m/s by the low resolution spectral processing and low second-order power. An upper limit is suggested by the steep slope in the region of the sea backscatter spectrum outside the square root of two times the first-order Bragg line Doppler.

An Asymptotic Expansion for the Distribution of a Statistic Admitting an Asymptotic Expansion

An Asymptotic Expansion for the Distribution of a Statistic Admitting an Asymptotic Expansion

Isotope Exchange Rates. V. The Homogeneous Reaction between H2S and D2

Single-pulse shock-tube data were obtained for the homogeneous isotopic exchange reaction between deuterium and hydrogen sulfide, highly diluted in argon, over the temperature range 1260–1590°K. Three sets of experiments were performed independently in two laboratories. H2S/D2 ratios were varied over the range 4/1–1/4, at total reaction densities from 6 × 10−6 to 5 × 10−5 moles/cm3. The agreement among the three sets of data is generally good. An average activation energy of 52 ± 3 kcal/mole was deduced from them. All three sets of data may be fitted by a second-order power rate expression which is first order in D2 and roughly 12 order with respect to H2S and to Ar. These data support a mechanism, suggested previously for similar isotopic exchange reactions, in which metathesis reactions during collisions between H2S and D2 occur with significant probability only when the deuterium molecule contains at least a critical amount of vibrational energy. The rate-limiting process is the maintainance of an adequate population in the 4th and 5th vibrational levels of deuterium. The relative efficiencies for excitation of deuterium by collisions with the various species present, as determined from the kinetics data, are in reasonable agreement with values determined directly from vibrational relaxation studies.