**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**458

# Search results for: Gravity gradient

##### 458 Mathematical Modeling of the Working Principle of Gravity Gradient Instrument

**Authors:**
Danni Cong,
Meiping Wu,
Hua Mu,
Xiaofeng He,
Junxiang Lian,
Juliang Cao,
Shaokun Cai,
Hao Qin

**Abstract:**

**Keywords:**
Gravity gradient,
accelerometer,
gravity gradient sensor,
single-axis rotation modulation.

##### 457 Hybrid Gravity Gradient Inversion-Ant Colony Optimization Algorithm for Motion Planning of Mobile Robots

**Authors:**
Meng Wu

**Abstract:**

Motion planning is a common task required to be fulfilled by robots. A strategy combining Ant Colony Optimization (ACO) and gravity gradient inversion algorithm is proposed for motion planning of mobile robots. In this paper, in order to realize optimal motion planning strategy, the cost function in ACO is designed based on gravity gradient inversion algorithm. The obstacles around mobile robot can cause gravity gradient anomalies; the gradiometer is installed on the mobile robot to detect the gravity gradient anomalies. After obtaining the anomalies, gravity gradient inversion algorithm is employed to calculate relative distance and orientation between mobile robot and obstacles. The relative distance and orientation deduced from gravity gradient inversion algorithm is employed as cost function in ACO algorithm to realize motion planning. The proposed strategy is validated by the simulation and experiment results.

**Keywords:**
Motion planning,
gravity gradient inversion algorithm,
ant colony optimization.

##### 456 Calibration of the Radical Installation Limit Error of the Accelerometer in the Gravity Gradient Instrument

**Authors:**
Danni Cong,
Meiping Wu,
Xiaofeng He,
Junxiang Lian,
Juliang Cao,
Shaokuncai,
Hao Qin

**Abstract:**

**Keywords:**
Gravity gradient sensor,
radial installation limit error,
accelerometer,
uniaxial rotational modulation.

##### 455 Investigation of Buoyant Parameters of k-ε Turbulence Model in Gravity Stratified Flows

**Authors:**
A. Majid Bahari,
Kourosh Hejazi

**Abstract:**

Different variants for buoyancy-affected terms in k-ε turbulence model have been utilized to predict the flow parameters more accurately, and investigate applicability of alternative k-ε turbulence buoyant closures in numerical simulation of a horizontal gravity current. The additional non-isotropic turbulent stress due to buoyancy has been considered in production term, based on Algebraic Stress Model (ASM). In order to account for turbulent scalar fluxes, general gradient diffusion hypothesis has been used along with Boussinesq gradient diffusion hypothesis with a variable turbulent Schmidt number and additional empirical constant c3ε.To simulate buoyant flow domain a 2D vertical numerical model (WISE, Width Integrated Stratified Environments), based on Reynolds- Averaged Navier-Stokes (RANS) equations, has been deployed and the model has been further developed for different k-ε turbulence closures. Results are compared against measured laboratory values of a saline gravity current to explore the efficient turbulence model.

**Keywords:**
Buoyant flows,
Buoyant k-ε turbulence model,
saline gravity current.

##### 454 Design of Gravity Dam by Genetic Algorithms

**Authors:**
Farzin Salmasi

**Abstract:**

**Keywords:**
Chromosomes,
dam,
genetic algorithm,
globaloptimum,
preliminary layout,
stress analysis,
theoretical profile.

##### 453 Exploring Solutions in Extended Horava-Lifshitz Gravity

**Authors:**
Aziza Altaibayeva,
Ertan Gudekli,
Ratbay Myrzakulov

**Abstract:**

In this letter, we explore exact solutions for the Horava-Lifshitz gravity. We use of an extension of this theory with first order dynamical lapse function. The equations of motion have been derived in a fully consistent scenario. We assume that there are some spherically symmetric families of exact solutions of this extended theory of gravity. We obtain exact solutions and investigate the singularity structures of these solutions. Specially, an exact solution with the regular horizon is found.

**Keywords:**
Quantum gravity,
Horava-Lifshitz gravity,
black hole,
spherically symmetric space times.

##### 452 Simulating Gradient Contour and Mesh of a Scalar Field

**Authors:**
Usman Ali Khan,
Bismah Tariq,
Khalida Raza,
Saima Malik,
Aoun Muhammad

**Abstract:**

**Keywords:**
MATLAB,
Gradient,
Contour,
Scalar Field,
Mesh

##### 451 The Evaluation of Gravity Anomalies Based on Global Models by Land Gravity Data

**Authors:**
M. Yilmaz,
I. Yilmaz,
M. Uysal

**Abstract:**

The Earth system generates different phenomena that are observable at the surface of the Earth such as mass deformations and displacements leading to plate tectonics, earthquakes, and volcanism. The dynamic processes associated with the interior, surface, and atmosphere of the Earth affect the three pillars of geodesy: shape of the Earth, its gravity field, and its rotation. Geodesy establishes a characteristic structure in order to define, monitor, and predict of the whole Earth system. The traditional and new instruments, observables, and techniques in geodesy are related to the gravity field. Therefore, the geodesy monitors the gravity field and its temporal variability in order to transform the geodetic observations made on the physical surface of the Earth into the geometrical surface in which positions are mathematically defined. In this paper, the main components of the gravity field modeling, (Free-air and Bouguer) gravity anomalies are calculated via recent global models (EGM2008, EIGEN6C4, and GECO) over a selected study area. The model-based gravity anomalies are compared with the corresponding terrestrial gravity data in terms of standard deviation (SD) and root mean square error (RMSE) for determining the best fit global model in the study area at a regional scale in Turkey. The least SD (13.63 mGal) and RMSE (15.71 mGal) were obtained by EGM2008 for the Free-air gravity anomaly residuals. For the Bouguer gravity anomaly residuals, EIGEN6C4 provides the least SD (8.05 mGal) and RMSE (8.12 mGal). The results indicated that EIGEN6C4 can be a useful tool for modeling the gravity field of the Earth over the study area.

**Keywords:**
Free-air gravity anomaly,
Bouguer gravity anomaly,
global model,
land gravity.

##### 450 Conformal Invariance in F (R, T) Gravity

**Authors:**
Pyotr Tsyba,
Olga Razina,
Ertan Güdekli,
Ratbay Myrzakulov

**Abstract:**

In this paper we consider the equation of motion for the F (R, T) gravity on their property of conformal invariance. It is shown that in the general case, such a theory is not conformal invariant. Studied special cases for the functions v and u in which can appear properties of the theory. Also we consider cosmological aspects F (R, T) theory of gravity, having considered particular case F (R, T) = μR+νT^2. Showed that in this case there is a nonlinear dependence of the parameter equation of state from time to time, which affects its evolution.

**Keywords:**
Conformally invariance,
F (R,
T) gravity,
metric
FRW,
equation of motion,
dark energy.

##### 449 Comparisons of Co-Seismic Gravity Changes between GRACE Observations and the Predictions from the Finite-Fault Models for the 2012 Mw = 8.6 Indian Ocean Earthquake Off-Sumatra

**Authors:**
Armin Rahimi

**Abstract:**

**Keywords:**
Undersea earthquake,
GRACE observation,
gravity change,
dislocation model,
slip distribution.

##### 448 A New Modification of Nonlinear Conjugate Gradient Coefficients with Global Convergence Properties

**Authors:**
Ahmad Alhawarat,
Mustafa Mamat,
Mohd Rivaie,
Ismail Mohd

**Abstract:**

**Keywords:**
Conjugate gradient method,
conjugate gradient
coefficient,
global convergence.

##### 447 Research on the Correlation of the Fluctuating Density Gradient of the Compressible Flows

**Authors:**
Yasuo Obikane

**Abstract:**

**Keywords:**
Turbulence Modeling ,
Density Gradient Correlation,
Compressible

##### 446 Segmentation of Noisy Digital Images with Stochastic Gradient Kernel

**Authors:**
Abhishek Neogi,
Jayesh Verma,
Pinaki Pratim Acharjya

**Abstract:**

**Keywords:**
Image segmentation,
edge Detection,
noisy images,
spatialfilters,
stochastic gradient kernel.

##### 445 Effect of Concrete Nonlinear Parameters on the Seismic Response of Concrete Gravity Dams

**Authors:**
Z. Heirany,
M. Ghaemian

**Abstract:**

**Keywords:**
Numerical methods; concrete gravity dams; finiteelement method; boundary condition

##### 444 Dynamic Measurement System Modeling with Machine Learning Algorithms

**Authors:**
Changqiao Wu,
Guoqing Ding,
Xin Chen

**Abstract:**

**Keywords:**
Dynamic system modeling,
neural network,
normal
equation,
second order gradient descent.

##### 443 Green Function and Eshelby Tensor Based on Mindlin’s 2nd Gradient Model: An Explicit Study of Spherical Inclusion Case

**Authors:**
A. Selmi,
A. Bisharat

**Abstract:**

Using Fourier transform and based on the Mindlin's 2^{nd} gradient model that involves two length scale parameters, the Green's function, the Eshelby tensor, and the Eshelby-like tensor for a spherical inclusion are derived. It is proved that the Eshelby tensor consists of two parts; the classical Eshelby tensor and a gradient part including the length scale parameters which enable the interpretation of the size effect. When the strain gradient is not taken into account, the obtained Green's function and Eshelby tensor reduce to its analogue based on the classical elasticity. The Eshelby tensor in and outside the inclusion, the volume average of the gradient part and the Eshelby-like tensor are explicitly obtained. Unlike the classical Eshelby tensor, the results show that the components of the new Eshelby tensor vary with the position and the inclusion dimensions. It is demonstrated that the contribution of the gradient part should not be neglected.

**Keywords:**
Eshelby tensor,
Eshelby-like tensor,
Green’s function,
Mindlin’s 2nd gradient model,
Spherical inclusion.

##### 442 Regional Low Gravity Anomalies Influencing High Concentrations of Heavy Minerals on Placer Deposits

**Authors:**
T. B. Karu Jayasundara

**Abstract:**

Regions of low gravity and gravity anomalies both influence heavy mineral concentrations on placer deposits. Economically imported heavy minerals are likely to have higher levels of deposition in low gravity regions of placer deposits. This can be found in coastal regions of Southern Asia, particularly in Sri Lanka and Peninsula India and areas located in the lowest gravity region of the world. The area about 70 kilometers of the east coast of Sri Lanka is covered by a high percentage of ilmenite deposits, and the southwest coast of the island consists of Monazite placer deposit. These deposits are one of the largest placer deposits in the world. In India, the heavy mineral industry has a good market. On the other hand, based on the coastal placer deposits recorded, the high gravity region located around Papua New Guinea, has no such heavy mineral deposits. In low gravity regions, with the help of other depositional environmental factors, the grains have more time and space to float in the sea, this helps bring high concentrations of heavy mineral deposits to the coast. The effect of low and high gravity can be demonstrated by using heavy mineral separation devices. The ** Wilfley** heavy mineral separating table is one of these; it is extensively used in industries and in laboratories for heavy mineral separation. The horizontally oscillating Wilfley table helps to separate heavy and light mineral grains in to deferent fractions, with the use of water. In this experiment, the low and high angle of the Wilfley table are representing low and high gravity respectively. A sample mixture of grain size <0.85 mm of heavy and light mineral grains has been used for this experiment. The high and low angle of the table was

*6*

*and 2*

^{0}*respectively for this experiment. The separated fractions from the table are again separated into heavy and light minerals, with the use of heavy liquid, which consists of a specific gravity of 2.85. The fractions of separated heavy and light minerals have been used for drawing the two-dimensional graphs. The graphs show that the low gravity stage has a high percentage of heavy minerals collected in the upper area of the table than in the high gravity stage. The results of the experiment can be used for the comparison of regional low gravity and high gravity levels of heavy minerals. If there are any heavy mineral deposits in the high gravity regions, these deposits will take place far away from the coast, within the continental shelf.*

^{0}**Keywords:**
Anomaly,
gravity,
influence,
mineral.

##### 441 Flexural Strength Design of RC Beams with Consideration of Strain Gradient Effect

**Authors:**
Mantai Chen,
Johnny Ching Ming Ho

**Abstract:**

The stress-strain relationship of concrete under flexure is one of the essential parameters in assessing ultimate flexural strength capacity of RC beams. Currently, the concrete stress-strain curve in flexure is obtained by incorporating a constant scale-down factor of 0.85 in the uniaxial stress-strain curve. However, it was revealed that strain gradient would improve the maximum concrete stress under flexure and concrete stress-strain curve is strain gradient dependent. Based on the strain-gradient-dependent concrete stress-strain curve, the investigation of the combined effects of strain gradient and concrete strength on flexural strength of RC beams was extended to high strength concrete up to 100 MPa by theoretical analysis. As an extension and application of the authors’ previous study, a new flexural strength design method incorporating the combined effects of strain gradient and concrete strength is developed. A set of equivalent rectangular concrete stress block parameters is proposed and applied to produce a series of design charts showing that the flexural strength of RC beams are improved with strain gradient effect considered.

**Keywords:**
Beams,
Equivalent concrete stress block,
Flexural strength,
Strain gradient.

##### 440 Learning Flexible Neural Networks for Pattern Recognition

**Authors:**
A. Mirzaaghazadeh,
H. Motameni,
M. Karshenas,
H. Nematzadeh

**Abstract:**

**Keywords:**
Back propagation,
Flexible,
Gradient,
Learning,
Neural network,
Pattern recognition.

##### 439 Growth and Anatomical Responses of Lycopersicon esculentum (Tomatoes) under Microgravity and Normal Gravity Conditions

**Authors:**
Gbenga F. Akomolafe,
Joseph Omojola,
Ezekiel S. Joshua,
Seyi C. Adediwura,
Elijah T. Adesuji,
Michael O. Odey,
Oyinade A. Dedeke,
Ayo H. Labulo

**Abstract:**

Microgravity is known to be a major abiotic stress in space which affects plants depending on the duration of exposure. In this work, tomatoes seeds were exposed to long hours of simulated microgravity condition using a one-axis clinostat. The seeds were sown on a 1.5% combination of plant nutrient and agar-agar solidified medium in three Petri dishes. One of the Petri dishes was mounted on the clinostat and allowed to rotate at the speed of 20 rpm for 72 hours, while the others were subjected to the normal gravity vector. The anatomical sections of both clinorotated and normal gravity plants were made after 72 hours and observed using a Phase-contrast digital microscope. The percentage germination, as well as the growth rate of the normal gravity seeds, was higher than the clinorotated ones. The germinated clinorotated roots followed different directions unlike the normal gravity ones which grew towards the direction of gravity vector. The clinostat was able to switch off gravistimulation. Distinct cellular arrangement was observed for tomatoes under normal gravity condition, unlike those of clinorotated ones. The root epidermis and cortex of normal gravity are thicker than the clinorotated ones. This implied that under long-term microgravity influence, plants do alter their anatomical features as a way of adapting to the stress condition.

**Keywords:**
Anatomy,
Clinostat,
Germination,
Microgravity,
Lycopersicon esculentum.

##### 438 Study on Liquid Nitrogen Gravity Circulation Loop for Cryopumps in Large Space Simulator

**Authors:**
Weiwei Shan,
Wenjing Ding,
Juan Ning,
Chao He,
Zijuan Wang

**Abstract:**

Gravity circulation loop for the cryopumps of the space simulator is introduced, and two phase mathematic model of flow heat transfer is analyzed as well. Based on this model, the liquid nitrogen (LN_{2}) gravity circulation loop including its equipment and layout is designed and has served as LN_{2} feeding system for cryopumps in one large space simulator. With the help of control software and human machine interface, this system can be operated flexibly, simply, and automatically under four conditions. When running this system, the results show that the cryopumps can be cooled down and maintained under the required temperature, 120 K.

**Keywords:**
Cryopumps,
gravity circulation loop,
liquid nitrogen,
two-phase.

##### 437 Impact of Viscous and Heat Relaxation Loss on the Critical Temperature Gradients of Thermoacoustic Stacks

**Authors:**
Zhibin Yu,
Artur J. Jaworski,
Abdulrahman S. Abduljalil

**Abstract:**

**Keywords:**
Critical temperature gradient,
heat relaxation,
stack,
viscous effect.

##### 436 A Refined Nonlocal Strain Gradient Theory for Assessing Scaling-Dependent Vibration Behavior of Microbeams

**Authors:**
Xiaobai Li,
Li Li,
Yujin Hu,
Weiming Deng,
Zhe Ding

**Abstract:**

**Keywords:**
Euler-Bernoulli Beams,
free vibration,
higher order
inertia,
nonlocal strain gradient theory,
velocity gradient.

##### 435 Comparison of Three Versions of Conjugate Gradient Method in Predicting an Unknown Irregular Boundary Profile

**Authors:**
V. Ghadamyari,
F. Samadi,
F. Kowsary

**Abstract:**

**Keywords:**
Boundary elements,
Conjugate Gradient Method,
Inverse Geometry Problem,
Sensitivity equation.

##### 434 An Improved Conjugate Gradient Based Learning Algorithm for Back Propagation Neural Networks

**Authors:**
N. M. Nawi,
R. S. Ransing,
M. R. Ransing

**Abstract:**

The conjugate gradient optimization algorithm is combined with the modified back propagation algorithm to yield a computationally efficient algorithm for training multilayer perceptron (MLP) networks (CGFR/AG). The computational efficiency is enhanced by adaptively modifying initial search direction as described in the following steps: (1) Modification on standard back propagation algorithm by introducing a gain variation term in the activation function, (2) Calculation of the gradient descent of error with respect to the weights and gains values and (3) the determination of a new search direction by using information calculated in step (2). The performance of the proposed method is demonstrated by comparing accuracy and computation time with the conjugate gradient algorithm used in MATLAB neural network toolbox. The results show that the computational efficiency of the proposed method was better than the standard conjugate gradient algorithm.

**Keywords:**
Adaptive gain variation,
back-propagation,
activation function,
conjugate gradient,
search direction.

##### 433 Geopotential Models Evaluation in Algeria Using Stochastic Method, GPS/Leveling and Topographic Data

**Authors:**
M. A. Meslem

**Abstract:**

For precise geoid determination, we use a reference field to subtract long and medium wavelength of the gravity field from observations data when we use the remove-compute-restore technique. Therefore, a comparison study between considered models should be made in order to select the optimal reference gravity field to be used. In this context, two recent global geopotential models have been selected to perform this comparison study over Northern Algeria. The Earth Gravitational Model (EGM2008) and the Global Gravity Model (GECO) conceived with a combination of the first model with anomalous potential derived from a GOCE satellite-only global model. Free air gravity anomalies in the area under study have been used to compute residual data using both gravity field models and a Digital Terrain Model (DTM) to subtract the residual terrain effect from the gravity observations. Residual data were used to generate local empirical covariance functions and their fitting to the closed form in order to compare their statistical behaviors according to both cases. Finally, height anomalies were computed from both geopotential models and compared to a set of GPS levelled points on benchmarks using least squares adjustment. The result described in details in this paper regarding these two models has pointed out a slight advantage of GECO global model globally through error degree variances comparison and ground-truth evaluation.

**Keywords:**
Quasigeoid,
gravity anomalies,
covariance,
GGM.

##### 432 The Influence of Gravity on The Temporal Instability of Viscoelastic Liquid Curved Jets

**Authors:**
Abdullah Madhi Alsharif,
Jamal Uddin

**Abstract:**

A liquid curved jet has many applications in different industrial and engineering processes, such as the prilling process for generating small spherical pellets (fertilizer or magnesium). The liquids used are usually molten and contain small quantities of polymers and therefore can be modelled as non-Newtonian liquids. In this paper, we model the viscoelastic liquid jet by using the Oldroyd- B model. An asymptotic analysis has been used to simplify the governing equations. Furthermore, the trajectory and a linear temporal stability in the presence of gravity and rotation have been determined.

**Keywords:**
gravity,
prilling,
rotation,
viscoelastic jets.

##### 431 Effect of Particle Gravity on the Fractal Dimension of Particle Line in three-dimensional Turbulent Flows using Kinematic Simulation

**Authors:**
A. Abou El-Azm Aly,
F. Nicolleau,
T. M. Michelitsch,
A. F. Nowakowski

**Abstract:**

**Keywords:**
Heavy particles,
two-phase flow,
Kinematic Simulation,
Fractal dimension.

##### 430 Model Free Terminal Sliding Mode with Gravity Compensation: Application to an Exoskeleton-Upper Limb System

**Authors:**
Sana Bembli,
Nahla Khraief Haddad,
Safya Belghith

**Abstract:**

**Keywords:**
Exoskeleton-upper limb system,
gravity compensation,
model free terminal sliding mode,
robustness analysis,
Monte Carlo,
H∞ methods.

##### 429 Conjugate Gradient Algorithm for the Symmetric Arrowhead Solution of Matrix Equation AXB=C

**Authors:**
Minghui Wang,
Luping Xu,
Juntao Zhang

**Abstract:**

*AXB=C*and the associate optimal approximation problem are considered for the symmetric arrowhead matrix solutions in the premise of consistency. The convergence results of the method are presented. At last, a numerical example is given to illustrate the efficiency of this method.

**Keywords:**
Iterative method,
symmetric arrowhead matrix,
conjugate gradient algorithm.