scholarly journals 3D full-time anisotropic TEM modelling using a mixed BDF2/SAI method

2021 ◽  
Vol 18 (6) ◽  
pp. 995-1006
Author(s):  
Kui Huang ◽  
Kailiang Lu ◽  
Jianmei Zhou ◽  
Xiu Li ◽  
Lifei Meng
Keyword(s):  
Krylov Subspace ◽  
Coefficient Matrix ◽  
Time Response ◽  
Full Time ◽  
Anisotropic Model ◽  
Require Time ◽  
Transient Electromagnetic ◽  
Time Period ◽  
Spatial Discretisation ◽  
Off Time

Abstract Transient electromagnetic (TEM) data are affected by resistivity anisotropy, which should be considered in 3D modelling. The influence of anisotropy on full-time response is the main focus of this research. For spatial discretisation of an anisotropic model, the mimetic finite volume approach was applied. The accuracy of the shift-and-invert (SAI) Krylov subspace approach and the two-step backward differentiation formula (BDF2) for modelling 3D full-time electromagnetic data has been demonstrated. However, both algorithms require time-consuming calculations. The SAI technique requires a number of projection subspace constructions, whereas the BDF2 algorithm necessitates numerous coefficient matrix decompositions. We proposed a novel mixed BDF2/SAI algorithm in this paper, which combines the advantages of the two algorithms. The on-time response is computed using BDF2, while the off-time response is computed using the SAI-Krylov subspace method. The forward results of a 1D model with a half-sine waveform demonstrated that the new algorithm is accurate and faster than both the BDF2 algorithm and the SAI algorithm. During the full-time period, the forward results of a 3D anisotropic model with half-sine waveform show that abnormal responses can be induced. It was shown that the relative abnormal of ${{{\bf b}}_{\boldsymbol{z}}}$ is higher during the on-time period, while the relative abnormal of $\partial {{{\bf b}}_{\boldsymbol{z}}}/\partial t$ is higher during the off-time period. Furthermore, the change in relative anomaly is more obvious as the anisotropic block rotates around the x-axis. And the larger the rotation angle, the larger the relative anomaly.

Stability and Change in Emotional Intelligence: Exploring the Transition to Young Adulthood

2005 ◽  
Vol 26 (2) ◽  
pp. 100-106 ◽  
Author(s):  
James D.A. Parker ◽  
Donald H. Saklofske ◽  
Laura M. Wood ◽  
Jennifer M. Eastabrook ◽  
Robyn N. Taylor
Keyword(s):  
High School ◽  
Emotional Intelligence ◽  
Postsecondary Education ◽  
Life Transition ◽  
Full Time ◽  
Major Life ◽  
Long Term Stability ◽  
Time Period ◽  
Transition From High School

Abstract. The concept of emotional intelligence (EI) has attracted growing interest from researchers working in various fields. The present study examined the long-term stability (32 months) of EI-related abilities over the course of a major life transition (the transition from high school to university). During the first week of full-time study, a large group of undergraduates completed the EQ-i:Short; 32 months later a random subset of these students (N = 238), who had started their postsecondary education within 24 months of graduating from high school, completed the measures for a second time. The study found EI scores to be relatively stable over the 32-month time period. EI scores were also found to be significantly higher at Time 2; the overall pattern of change in EI-levels was more than can be attributed to the increased age of the participants.

scholarly journals Adjoint-based exact Hessian computation

2021 ◽  
Author(s):  
Shin-ichi Ito ◽  
Takeru Matsuda ◽  
Yuto Miyatake
Keyword(s):  
Krylov Subspace ◽  
Hessian Matrix ◽  
Adjoint System ◽  
Coefficient Matrix ◽  
Scalar Function ◽  
Second Order ◽  
Subspace Method ◽  
Initial Value ◽  
Research Fields ◽  
Memory Efficiency

AbstractWe consider a scalar function depending on a numerical solution of an initial value problem, and its second-derivative (Hessian) matrix for the initial value. The need to extract the information of the Hessian or to solve a linear system having the Hessian as a coefficient matrix arises in many research fields such as optimization, Bayesian estimation, and uncertainty quantification. From the perspective of memory efficiency, these tasks often employ a Krylov subspace method that does not need to hold the Hessian matrix explicitly and only requires computing the multiplication of the Hessian and a given vector. One of the ways to obtain an approximation of such Hessian-vector multiplication is to integrate the so-called second-order adjoint system numerically. However, the error in the approximation could be significant even if the numerical integration to the second-order adjoint system is sufficiently accurate. This paper presents a novel algorithm that computes the intended Hessian-vector multiplication exactly and efficiently. For this aim, we give a new concise derivation of the second-order adjoint system and show that the intended multiplication can be computed exactly by applying a particular numerical method to the second-order adjoint system. In the discussion, symplectic partitioned Runge–Kutta methods play an essential role.

A Kind of Preconditioned IGMRES(m) Algorithm

2012 ◽  
Vol 482-484 ◽  
pp. 413-416
Author(s):  
Chun Xiao Yu
Keyword(s):  
Krylov Subspace ◽  
Matrix Decomposition ◽  
Coefficient Matrix ◽  
Algebraic Equations ◽  
Residual Method ◽  
Minimal Residual Method ◽  
Algorithm Convergence ◽  
Minimal Residual

Fundamental theories are studied for an Incomplete Generalized Minimal Residual Method(IGMRES(m)) in Krylov subspace. An algebraic equations generated from the IGMRES(m) algorithm is presented. The relationships are deeply researched for the algorithm convergence and the coefficient matrix of the equations. A kind of preconditioned method is proposed to improve the convergence of the IGMRES(m) algorithm. It is proved that the best convergence can be obtained through appropriate matrix decomposition.

3-D Full-Time TEM Modeling Using Shift-and-Invert Krylov Subspace Method

2020 ◽  
Vol 58 (10) ◽  
pp. 7096-7104
Author(s):  
Jianmei Zhou ◽  
Wentao Liu ◽  
Xiu Li ◽  
Yanfu Qi ◽  
Zhipeng Qi
Keyword(s):  
Krylov Subspace ◽  
Krylov Subspace Method ◽  
Full Time ◽  
Subspace Method

scholarly journals Double Trapezoidal Wave Transmitting System with Controllable Turn-Off Edge

2020 ◽  
Vol 10 (21) ◽  
pp. 7932
Author(s):  
Yuan Jiang ◽  
Yanju Ji ◽  
Yibing Yu ◽  
Shipeng Wang ◽  
Yuan Wang
Keyword(s):  
Polarization Effect ◽  
Induced Polarization ◽  
Emission Current ◽  
Wire Loop ◽  
Transient Electromagnetic ◽  
Charging Time ◽  
The Earth ◽  
Electromagnetic Measurement ◽  
Induced Polarization Effect ◽  
Off Time

For time domain transient electromagnetic measurement, the negative sign often appears in the polarization region, which contains the induced polarization information. It is considered that the polarization effect is caused by the capacitance charge of the earth. Extending the turn-off time of the emission current means increasing the charging time, and reducing the charging voltage, which makes the polarization effect easier to observe. Therefore, a double trapezoidal wave transmitting system with a controllable turn-off edge is designed in this paper. In the process of current transmitting, the turn-off time can be controlled by changing the clamping voltage depending on the passive clamping technology. By cutting into the absorption resistance, the current oscillation can be eliminated under the condition of ensuring linearity. To verify the effectiveness of the system, we designed a polarized wire loop based on the filament model simulating the polarized earth. Comparing the response of the wire loop, the emission current with short and long turn-off times contributes to inducing the induction and polarization fields respectively. The double trapezoidal wave transmitting system with a controllable turn-off edge is suitable for measuring the induced polarization effect.

scholarly journals A Multidiagnostic Intercomparison of Tropical-Width Time Series Using Reanalyses and Satellite Observations

2012 ◽  
Vol 25 (4) ◽  
pp. 1061-1078 ◽  
Author(s):  
Sean M. Davis ◽  
Karen H. Rosenlof
Keyword(s):  
Longwave Radiation ◽  
Hadley Cell ◽  
Radiosonde Data ◽  
Full Time ◽  
Robust Detection ◽  
Time Period ◽  
Wide Range ◽  
The Mean ◽  
Yield Trends ◽  
The Tropics

Abstract Poleward migration of the latitudinal edge of the tropics of 0.25°–3.0° decade−1 has been reported in several recent studies based on satellite and radiosonde data and reanalysis output covering the past ~30 yr. The goal of this paper is to identify the extent to which this large range of trends can be explained by the use of different data sources, time periods, and edge definitions, as well as how the widening varies as a function of hemisphere and season. Toward this end, a suite of tropical edge latitude diagnostics based on tropopause height, winds, precipitation–evaporation, and outgoing longwave radiation (OLR) are analyzed using several reanalyses and satellite datasets. These diagnostics include both previously used definitions and new definitions designed for more robust detection. The wide range of widening trends is shown to be primarily due to the use of different datasets and edge definitions and only secondarily due to varying start–end dates. This study also shows that the large trends (>~1° decade−1) previously reported in tropopause and OLR diagnostics are due to the use of subjective definitions based on absolute thresholds. Statistically significant Hadley cell expansion based on the mean meridional streamfunction of 1.0°–1.5° decade−1 is found in three of four reanalyses that cover the full time period (1979–2009), whereas other diagnostics yield trends of −0.5°–0.8° decade−1 that are mostly insignificant. There are indications of hemispheric and seasonal differences in the trends, but the differences are not statistically significant.

scholarly journals Liaison psychiatry continues to expand: developing services in the British Isles

2003 ◽  
Vol 27 (9) ◽  
pp. 339-341 ◽  
Author(s):  
Geraldine Swift ◽  
Else Guthrie
Keyword(s):  
Local Development ◽  
Postal Survey ◽  
Full Time ◽  
Liaison Psychiatry ◽  
Specialist Registrar ◽  
Current State ◽  
Time Period ◽  
Wide Range ◽  
The Republic ◽  
The Uk

Aims and MethodA postal survey of consultants in liaison psychiatry was carried out in the spring of 2002 to document the current state of liaison psychiatry in the UK and the Republic of Ireland. Information was collected on post specifications, clinical organisation and plans for further local development.ResultsNinety-three liaison consultants were identified. Seventy-seven posts were full-time or half-time, compared with 43 such posts in 1996. During the same time period, specialist registrar training posts have doubled from 30 to 61. A third of respondents anticipated further consultant posts in their region.Clinical ImplicationsDespite the increase in the number of liaison consultants since 1996, the numbers still fall below that recommended by the Royal College of Psychiatrists. Liaison consultants need to improve links with primary care and continue to develop specialised services to demonstrate the qualitative and financial benefits that liaison psychiatry has to offer to a wide range of patients.

scholarly journals Full-time response of starch subjected to microwave heating

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Daming Fan ◽  
Liyun Wang ◽  
Nana Zhang ◽  
Lei Xiong ◽  
Luelue Huang ◽  
...  
Keyword(s):  
Microwave Heating ◽  
Time Response ◽  
Full Time

scholarly journals Global apparent resistivity definition for a high-performance TEM excitation source

2020 ◽  
Author(s):  
He Li ◽  
Wenhan Li ◽  
Zhipeng Qi ◽  
Xiu Li ◽  
Kailiang Lu
Keyword(s):  
High Resolution ◽  
High Performance ◽  
Apparent Resistivity ◽  
Inverse Function ◽  
Excitation Source ◽  
Underground Space ◽  
Electromagnetic Excitation ◽  
Transient Electromagnetic ◽  
Time Period ◽  
Calculation Results

Abstract The high-performance transient electromagnetic method (TEM) excitation source is a new type of source that has been proposed for urban underground space exploration. This source is composed of two trapezoid plates. To ensure that the radiation field was focused in a certain direction, the two trapezoid plate-shaped antennas were arranged into a horn shape. This new source is characterised by high power, directional excitation and high resolution. The corresponding multi-component global apparent resistivity definition method is established for a high-performance transient electromagnetic excitation source. This method is studied using the inverse function theorem. Then, the monotonic relationship between components of the electromagnetic field and resistivity is analysed. For the fields that satisfy the monotonic relationship with half-space resistivity, the apparent resistivity can be calculated correctly to ignore the time period and location in the space. This means that this definition method can eliminate the limitation of early and late times, and the near and far zones. The apparent resistivity calculation results of the theoretical layered model reveal that global apparent resistivity curves show a regular change, which smoothly and comprehensively reflects the change of electrical information in the model. The experimental results of the 3D model show that the five-layer low-resistivity anomaly contained in the urban underground space designed in this paper exhibits an obvious response in the global apparent resistivity profile. It is concluded that a high-performance TEM excitation source possesses a high resolution, clearly reflecting all of the anomalies of a complex urban underground space model.

scholarly journals Term Limits and the Increased Election of Women: Evidence From State Legislatures and the U.S. House of Representatives

2009 ◽  
Vol 30 ◽  
pp. 275-287
Author(s):  
Stanley M. Caress
Keyword(s):  
Growth Rate ◽  
House Of Representatives ◽  
Initial Period ◽  
State Legislatures ◽  
State Legislature ◽  
Term Limits ◽  
Full Time ◽  
Female Candidates ◽  
Time Period ◽  
The U.S

This study seeks to determine if term limits increase the likelihood of women being elected to legislative seats. Using a simple comparison of growth rates, we found that, during the initial period of term limit implementation (1991 to 2009), the increase of females elected to state legislatures with term limits was approximately the same as to those without term limits. Additionally, a comparison of the growth rate of females elected to the non-term-limited United States House of Representatives with those of the state legislatures during this same time period shows that the U.S. House actually had a greater increase than state legislatures both with and without term limits. Moreover, in California, which has a full-time, professional state legislature with electoral dynamics similar to the U.S. House, the proportion of women elected to the state’s non-term limited U.S. House delegation from 1990 to 2009 exceeded the proportion of women elected to its term-limited state legislature. These comparisons all suggest that term limits do not facilitate the election of female candidates to legislative seats.

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