**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**918

# Search results for: Frictional coefficient

##### 918 Improvement of Frictional Coefficient of Modified Shoe Soles onto Icy and Snowy Road by Tilting of Added Glass Fibers into Rubber

**Authors:**
Shunya Wakayama,
Kazuya Okubo,
Toru Fujii,
Daisuke Sakata,
Noriyuki Kado,
Hiroshi Furutachi

**Abstract:**

**Keywords:**
Frictional coefficient,
icy and snowy road,
shoe rubber soles,
tilting angle.

##### 917 Moderation in Temperature Dependence on Counter Frictional Coefficient and Prevention of Wear of C/C Composites by Synthesizing SiC around Surface and Internal Vacancies

**Authors:**
Noboru Wakamoto,
Kiyotaka Obunai,
Kazuya Okubo,
Toru Fujii

**Abstract:**

The aim of this study is to moderate the dependence of counter frictional coefficient on temperature between counter surfaces and to reduce the wear of C/C composites at low temperature. To modify the C/C composites, Silica (SiO_{2}) powders were added into phenolic resin for carbon precursor. The preform plate of the precursor of C/C composites was prepared by conventional filament winding method. The C/C composites plates were obtained by carbonizing preform plate at 2200 °C under an argon atmosphere. At that time, the silicon carbides (SiC) were synthesized around the surfaces and the internal vacancies of the C/C composites. The frictional coefficient on the counter surfaces and specific wear volumes of the C/C composites were measured by our developed frictional test machine like pin-on disk type. The XRD indicated that SiC was synthesized in the body of C/C composite fabricated by current method. The results of friction test showed that coefficient of friction of unmodified C/C composites have temperature dependence when the test condition was changed. In contrast, frictional coefficient of the C/C composite modified with SiO_{2 }powders was almost constant at about 0.27 when the temperature condition was changed from Room Temperature (RT) to 300 °C. The specific wear rate decreased from 25×10^{-6} mm^{2}/N to 0.1×10^{-6} mm^{2}/N. The observations of the surfaces after friction tests showed that the frictional surface of the modified C/C composites was covered with a film produced by the friction. This study found that synthesizing SiC around surface and internal vacancies of C/C composites was effective to moderate the dependence on the frictional coefficient and reduce to the abrasion of C/C composites.

**Keywords:**
C/C composites,
frictional coefficient,
SiC,
wear.

##### 916 Effect of Friction Models on Stress Distribution of Sheet Materials during V-Bending Process

**Authors:**
Maziar Ramezani,
Zaidi Mohd Ripin

**Abstract:**

**Keywords:**
Friction model,
Stress distribution,
V-bending.

##### 915 Effects of Test Environment on the Sliding Wear Behaviour of Cast Iron, Zinc-Aluminium Alloy and Its Composite

**Authors:**
Mohammad M. Khan,
Gajendra Dixit

**Abstract:**

Partially lubricated sliding wear behaviour of a zinc-based alloy reinforced with 10wt% SiC particles has been studied as a function of applied load and solid lubricant particle size and has been compared with that of matrix alloy and conventionally used grey cast iron. The wear tests were conducted at the sliding velocities of 2.1m/sec in various partial lubricated conditions using pin on disc machine as per ASTM G-99-05. Base oil (SAE 20W-40) or mixture of the base oil with 5wt% graphite of particle sizes (7-10 µm) and (100 µm) were used for creating lubricated conditions. The matrix alloy revealed primary dendrites of a and eutectoid a + h and Î phases in the Inter dendritic regions. Similar microstructure has been depicted by the composite with an additional presence of the dispersoid SiC particles. In the case of cast iron, flakes of graphite were observed in the matrix; the latter comprised of (majority of) pearlite and (limited quantity of) ferrite. Results show a large improvement in wear resistance of the zinc-based alloy after reinforcement with SiC particles. The cast iron shows intermediate response between the matrix alloy and composite. The solid lubrication improved the wear resistance and friction behaviour of both the reinforced and base alloy. Moreover, minimum wear rate is obtained in oil+ 5wt % graphite (7-10 µm) lubricated environment for the matrix alloy and composite while for cast iron addition of solid lubricant increases the wear rate and minimum wear rate is obtained in case of oil lubricated environment. The cast iron experienced higher frictional heating than the matrix alloy and composite in all the cases especially at higher load condition. As far as friction coefficient is concerned, a mixed trend of behaviour was noted. The wear rate and frictional heating increased with load while friction coefficient was affected in an opposite manner. Test duration influenced the frictional heating and friction coefficient of the samples in a mixed manner.

**Keywords:**
Solid lubricant,
sliding wear grey cast iron,
zinc based metal matrix composites.

##### 914 Simulations of Laminar Liquid Flows through Superhydrophobic Micro-Pipes

**Authors:**
Mohamed E. Eleshaky

**Abstract:**

This paper investigates the dynamic behavior of laminar water flows inside superhydrophobic micro-pipes patterned with square micro-posts features under different operating conditions. It also investigates the effects of air fraction and Reynolds number on the frictional performance of these pipes. Rather than modeling the air-water interfaces of superhydrophobic as a flat inflexible surface, a transient, incompressible, three-dimensional, volume-of-fluid (VOF) methodology has been employed to continuously track the air–water interface shape inside micro-pipes. Also, the entrance effects on the flow field have been taken into consideration. The results revealed the strong dependency of the frictional performance on the air fractions and Reynolds number. The frictional resistance reduction becomes increasingly more significant at large air fractions and low Reynolds numbers. Increasing Reynolds number has an adverse effect on the frictional resistance reduction.

**Keywords:**
Drag reduction,
laminar flow in micropipes,
numerical simulation,
superhyrophobic surfaces,
microposts.

##### 913 A Spiral Dynamic Optimised Hybrid Fuzzy Logic Controller for a Unicycle Mobile Robot on Irregular Terrains

**Authors:**
Abdullah M. Almeshal,
Mohammad R. Alenezi,
Talal H. Alzanki

**Abstract:**

This paper presents a hybrid fuzzy logic control strategy for a unicycle trajectory following robot on irregular terrains. In literature, researchers have presented the design of path tracking controllers of mobile robots on non-frictional surface. In this work, the robot is simulated to drive on irregular terrains with contrasting frictional profiles of peat and rough gravel. A hybrid fuzzy logic controller is utilised to stabilise and drive the robot precisely with the predefined trajectory and overcome the frictional impact. The controller gains and scaling factors were optimised using spiral dynamics optimisation algorithm to minimise the mean square error of the linear and angular velocities of the unicycle robot. The robot was simulated on various frictional surfaces and terrains and the controller was able to stabilise the robot with a superior performance that is shown via simulation results.

**Keywords:**
Fuzzy logic control,
mobile robot,
trajectory
tracking,
spiral dynamic algorithm.

##### 912 Two Phase Frictional Pressure Drop of Carbon Dioxide in Horizontal Micro Tubes

**Authors:**
M. Tarawneh

**Abstract:**

**Keywords:**
Two-phase flow,
frictional pressure drop,
horizontalmicro tube,
carbon dioxide,
condensers.

##### 911 Modeling and Simulating Reaction-Diffusion Systems with State-Dependent Diffusion Coefficients

**Authors:**
Paola Lecca,
Lorenzo Dematte,
Corrado Priami

**Abstract:**

The present models and simulation algorithms of intracellular stochastic kinetics are usually based on the premise that diffusion is so fast that the concentrations of all the involved species are homogeneous in space. However, recents experimental measurements of intracellular diffusion constants indicate that the assumption of a homogeneous well-stirred cytosol is not necessarily valid even for small prokaryotic cells. In this work a mathematical treatment of diffusion that can be incorporated in a stochastic algorithm simulating the dynamics of a reaction-diffusion system is presented. The movement of a molecule A from a region i to a region j of the space is represented as a first order reaction Ai k- ! Aj , where the rate constant k depends on the diffusion coefficient. The diffusion coefficients are modeled as function of the local concentration of the solutes, their intrinsic viscosities, their frictional coefficients and the temperature of the system. The stochastic time evolution of the system is given by the occurrence of diffusion events and chemical reaction events. At each time step an event (reaction or diffusion) is selected from a probability distribution of waiting times determined by the intrinsic reaction kinetics and diffusion dynamics. To demonstrate the method the simulation results of the reaction-diffusion system of chaperoneassisted protein folding in cytoplasm are shown.

**Keywords:**
Reaction-diffusion systems,
diffusion coefficient,
stochastic simulation algorithm.

##### 910 Prediction of Air-Water Two-Phase Frictional Pressure Drop Using Artificial Neural Network

**Authors:**
H. B. Mehta,
Vipul M. Patel,
Jyotirmay Banerjee

**Abstract:**

The present paper discusses the prediction of gas-liquid two-phase frictional pressure drop in a 2.12 mm horizontal circular minichannel using Artificial Neural Network (ANN). The experimental results are obtained with air as gas phase and water as liquid phase. The superficial gas velocity is kept in the range of 0.0236 m/s to 0.4722 m/s while the values of 0.0944 m/s, 0.1416 m/s and 0.1889 m/s are considered for superficial liquid velocity. The experimental results are predicted using different Artificial Neural Network (ANN) models. Networks used for prediction are radial basis, generalised regression, linear layer, cascade forward back propagation, feed forward back propagation, feed forward distributed time delay, layer recurrent, and Elman back propagation. Transfer functions used for networks are Linear (PURELIN), Logistic sigmoid (LOGSIG), tangent sigmoid (TANSIG) and Gaussian RBF. Combination of networks and transfer functions give different possible neural network models. These models are compared for Mean Absolute Relative Deviation (MARD) and Mean Relative Deviation (MRD) to identify the best predictive model of ANN.

**Keywords:**
Minichannel,
Two-Phase Flow,
Frictional Pressure Drop,
ANN,
MARD,
MRD.

##### 909 Effects of Solar Absorption Coefficient of External Wall on Building Energy Consumption

**Authors:**
Jian Yao,
Chengwen Yan

**Abstract:**

**Keywords:**
Solar absorption coefficient,
External wall,
Buildingenergy consumption.

##### 908 Bending Gradient Coefficient Correction for I-Beams

**Authors:**
H. R. Kazemi Nia,
A. Yeganeh Fallah

**Abstract:**

**Keywords:**
Beams critical moment,
Bending Gradient Coefficient,
finite element,
Lateral Torsional Buckling

##### 907 Investigation of Phytoextraction Coefficient Different Combination of Heavy Metals in Barley and Alfalfa

**Authors:**
F. Zaefarian,
M. Rezvani,
F. Rejali,
M.R. Ardakani

**Abstract:**

**Keywords:**
phytoextraction coefficient,
heavy metals,
barley,
alfalfa

##### 906 Numerical Study of Flow around Flat Tube between Parallel Walls

**Authors:**
Hamidreza Bayat,
Arash Mirabdolah Lavasani,
Meysam Bolhasani,
Sajad Moosavi

**Abstract:**

Flow around a flat tube is studied numerically. Reynolds number is defined base on equivalent circular tube and it is varied in range of 100 to 300. Equations are solved by using finite volume method and results are presented in form of drag and lift coefficient. Results show that drag coefficient of flat tube is up to 66% lower than circular tube with equivalent diameter. In addition, by increasing *l*/D from 1 to 2, the drag coefficient of flat tube is decreased about 14-27%.

**Keywords:**
Laminar flow,
flat-tube,
drag coefficient,
cross-flow,
heat exchanger.

##### 905 A Study of the Change of Damping Coefficient Regarding Minimum Displacement

**Authors:**
Tawiwat V.,
Narongkorn D.,
Auttapoom L.

**Abstract:**

This research proposes the change of damping coefficient regarding minimum displacement. From the mass with external forced and damper problem, when is the constant external forced transmitted to the understructure in the difference angle between 30 and 60 degrees. This force generates the vibration as general known; however, the objective of this problem is to have minimum displacement. As the angle is changed and the goal is the same; therefore, the damper of the system must be varied while keeping constant spring stiffness. The problem is solved by using nonlinear programming and the suitable changing of the damping coefficient is provided.

**Keywords:**
Damping coefficient,
Optimal control,
Minimum Displacement and Vibration

##### 904 A Study on the Determinants of Earnings Response Coefficient in an Emerging Market

**Authors:**
Bita Mashayekhi,
Zeynab Lotfi Aghel

**Abstract:**

**Keywords:**
Earnings response coefficient,
return response coefficient,
firm size,
earnings growth,
earnings persistence.

##### 903 Preparing the Curve Number (CN) and Surface Runoff Coefficient (C) Map of the Basin in the Aghche Watershed, Iran

**Authors:**
Ali Gholami,
Ebrahim Panahpour,
Amir Hossein Davami

**Abstract:**

**Keywords:**
Aghche Watershed,
Curve Numbers (CV),
Land UseChanges,
Surface Runoff Coefficient(C) Map,
W indicator

##### 902 Mass Transfer of Palm Kernel Oil under Supercritical Conditions

**Authors:**
I. Norhuda,
A. K. Mohd Omar

**Abstract:**

The purpose of the study was to determine the amount of Palm Kernel Oil (PKO) extracted from a packed bed of palm kernels in a supercritical fluid extractor using supercritical carbon dioxide (SC-CO2) as an environmental friendly solvent. Further, the study sought to ascertain the values of the overall mass transfer coefficient (K) of PKO evaluation through a mass transfer model, at constant temperature of 50 °C, 60 °C, and 70 °C and pressures range from 27.6 MPa, 34.5 MPa, 41.4 MPa and 48.3 MPa respectively. Finally, the study also seeks to demonstrate the application of the overall mass transfer coefficient values in relation to temperature and pressure. The overall mass transfer coefficient was found to be dependent pressure at each constant temperature of 50 °C, 60 °C and 70 °C. The overall mass transfer coefficient for PKO in a packed bed of palm kernels was found to be in the range of 1.21X 10-4 m min-1 to 1.72 X 10-4 m min-1 for a constant temperature of 50 °C and in the range of 2.02 X 10-4 m min-1 to 2.43 X 10-4 m min-1 for a constant temperature of 60 °C. Similar increasing trend of the overall mass transfer coefficient from 1.77 X 10-4 m min-1 to 3.64 X 10-4 m min-1 was also observed at constant temperature of 70 °C within the same pressure range from 27.6 MPa to 48.3 MPa.

**Keywords:**
Overall Mass Transfer Coefficient (D),
Supercritical
Carbon Dioxide (SC-CO2),
Palm Kernel Oil (PKO).

##### 901 Mathematical Modeling of Wind Energy System for Designing Fault Tolerant Control

**Authors:**
Patil Ashwini,
Archana Thosar

**Abstract:**

This paper addresses the mathematical model of wind energy system useful for designing fault tolerant control. To serve the demand of power, large capacity wind energy systems are vital. These systems are installed offshore where non planned service is very costly. Whenever there is a fault in between two planned services, the system may stop working abruptly. This might even lead to the complete failure of the system. To enhance the reliability, the availability and reduce the cost of maintenance of wind turbines, the fault tolerant control systems are very essential. For designing any control system, an appropriate mathematical model is always needed. In this paper, the two-mass model is modified by considering the frequent mechanical faults like misalignments in the drive train, gears and bearings faults. These faults are subject to a wear process and cause frictional losses. This paper addresses these faults in the mathematics of the wind energy system. Further, the work is extended to study the variations of the parameters namely generator inertia constant, spring constant, viscous friction coefficient and gear ratio; on the pole-zero plot which is related with the physical design of the wind turbine. Behavior of the wind turbine during drive train faults are simulated and briefly discussed.

**Keywords:**
Mathematical model of wind energy system,
stability analysis,
shaft stiffness,
viscous friction coefficient,
gear ratio,
generator inertia,
fault tolerant control.

##### 900 The Design Optimization for Sound Absorption Material of Multi-Layer Structure

**Authors:**
Un-Hwan Park,
Jun-Hyeok Heo,
In-Sung Lee,
Tae-Hyeon Oh,
Dae-Kyu Park

**Abstract:**

Sound absorbing material is used as automotive interior material. Sound absorption coefficient should be predicted to design it. But it is difficult to predict sound absorbing coefficient because it is comprised of several material layers. So, its targets are achieved through many experimental tunings. It causes a lot of cost and time. In this paper, we propose the process to estimate the sound absorption coefficient with multi-layer structure. In order to estimate the coefficient, physical properties of each material are used. These properties also use predicted values by Foam-X software using the sound absorption coefficient data measured by impedance tube. Since there are many physical properties and the measurement equipment is expensive, the values predicted by software are used. Through the measurement of the sound absorption coefficient of each material, its physical properties are calculated inversely. The properties of each material are used to calculate the sound absorption coefficient of the multi-layer material. Since the absorption coefficient of multi-layer can be calculated, optimization design is possible through simulation. Then, we will compare and analyze the calculated sound absorption coefficient with the data measured by scaled reverberation chamber and impedance tubes for a prototype. If this method is used when developing automotive interior materials with multi-layer structure, the development effort can be reduced because it can be optimized by simulation. So, cost and time can be saved.

**Keywords:**
Optimization design,
multi-layer nonwoven,
sound absorption coefficient,
scaled reverberation chamber,
impedance tubes.

##### 899 Confidence Intervals for the Normal Mean with Known Coefficient of Variation

**Authors:**
Suparat Niwitpong

**Abstract:**

In this paper we proposed two new confidence intervals for the normal population mean with known coefficient of variation. This situation occurs normally in environment and agriculture experiments where the scientist knows the coefficient of variation of their experiments. We propose two new confidence intervals for this problem based on the recent work of Searls [5] and the new method proposed in this paper for the first time. We derive analytic expressions for the coverage probability and the expected length of each confidence interval. Monte Carlo simulation will be used to assess the performance of these intervals based on their expected lengths.

**Keywords:**
confidence interval,
coverage probability,
expected length,
known coefficient of variation.

##### 898 Approximations to the Distribution of the Sample Correlation Coefficient

**Authors:**
John N. Haddad,
Serge B. Provost

**Abstract:**

**Keywords:**
Sample correlation coefficient,
density approximation,
confidence intervals.

##### 897 On Quasi Conformally Flat LP-Sasakian Manifolds with a Coefficient α

**Authors:**
Jay Prakash Singh

**Abstract:**

**Keywords:**
LP-Sasakian manifolds,
coefficient α,
quasi conformal
curvature tensor,
concircular vector field,
torse forming vector field,
η-Einstein manifold.

##### 896 Confidence Interval for the Inverse of a Normal Mean with a Known Coefficient of Variation

**Authors:**
Arunee Wongkha,
Suparat Niwitpong,
Sa-aat Niwitpong

**Abstract:**

In this paper, we propose two new confidence intervals for the inverse of a normal mean with a known coefficient of variation. One of new confidence intervals for the inverse of a normal mean with a known coefficient of variation is constructed based on the pivotal statistic Z where Z is a standard normal distribution and another confidence interval is constructed based on the generalized confidence interval, presented by Weerahandi. We examine the performance of these confidence intervals in terms of coverage probabilities and average lengths via Monte Carlo simulation.

**Keywords:**
The inverse of a normal mean,
confidence interval,
generalized confidence intervals,
known coefficient of variation.

##### 895 Generalization of Clustering Coefficient on Lattice Networks Applied to Criminal Networks

**Authors:**
Christian H. Sanabria-Montaña,
Rodrigo Huerta-Quintanilla

**Abstract:**

**Keywords:**
Clustering coefficient,
criminology,
generalized,
regular network d-dimensional.

##### 894 Mathematical Models for Overall Gas Transfer Coefficient Using Different Theories and Evaluating Their Measurement Accuracy

**Authors:**
Shashank.B. Thakre,
Lalit.B. Bhuyar,
Samir.J. Deshmukh

**Abstract:**

**Keywords:**
Theories,
Dissolved oxygen,
Mathematical model,
Gas Transfer coefficient,
Accuracy.

##### 893 Performance Evaluation and Modeling of a Conical Plunging Jet Aerator

**Authors:**
Surinder Deswal,
D. V. S. Verma

**Abstract:**

Aeration by a plunging water jet is an energetically attractive way to effect oxygen-transfer than conventional oxygenation systems. In the present study, a new type of conical shaped plunging aeration device is fabricated to generate hollow inclined ined plunging jets (jet plunge angle of π/3 ) to investigate its oxygen transfer capacity. The results suggest that the volumetric oxygen-transfer coefficient and oxygen-transfer efficiency of the conical plunging jet aerator are competitive with other types of aeration systems. Relationships of volumetric oxygen-transfer coefficient with jet power per unit volume and jet parameters are also proposed. The suggested relationships predict the volumetric oxygentransfer coefficient within a scatter of ± 15% . Further, the application of Support Vector Machines on the experimental data revealed its utility in the prediction of volumetric oxygen-transfer coefficient and development of conical plunging jet aerators.

**Keywords:**
Conical plunging jet,
oxygen-transfer efficiency,
support vector machines,
volumetric oxygen-transfer coefficient.

##### 892 On Simple Confidence Intervals for the Normal Mean with Known Coefficient of Variation

**Authors:**
Suparat Niwitpong,
Sa-aat Niwitpong

**Abstract:**

In this paper we proposed the new confidence interval for the normal population mean with known coefficient of variation. In practice, this situation occurs normally in environment and agriculture sciences where we know the standard deviation is proportional to the mean. As a result, the coefficient of variation of is known. We propose the new confidence interval based on the recent work of Khan [3] and this new confidence interval will compare with our previous work, see, e.g. Niwitpong [5]. We derive analytic expressions for the coverage probability and the expected length of each confidence interval. A numerical method will be used to assess the performance of these intervals based on their expected lengths.

**Keywords:**
confidence interval,
coverage probability,
expected length,
known coefficient of variation.

##### 891 On the Hierarchical Ergodicity Coefficient

**Authors:**
Yilun Shang

**Abstract:**

In this paper, we deal with the fundamental concepts and properties of ergodicity coefficients in a hierarchical sense by making use of partition. Moreover, we establish a hierarchial Hajnal’s inequality improving some previous results.

**Keywords:**
Stochastic matrix,
ergodicity coefficient,
partition.

##### 890 CFD Analysis of Two Phase Flow in a Horizontal Pipe – Prediction of Pressure Drop

**Authors:**
P. Bhramara,
V. D. Rao,
K. V. Sharma ,
T. K. K. Reddy

**Abstract:**

**Keywords:**
Adiabatic conditions,
CFD analysis,
Homogeneousmodel and Liquid – Vapor flow.

##### 889 The Effect of Vibration on the Absorption of CO2 with Chemical Reaction in Aqueous Solution of Calcium Hydroxide

**Authors:**
B. Sohbi,
M. Emtir,
M. Elgarni

**Abstract:**

An interesting method to produce calcium carbonate is based in a gas-liquid reaction between carbon dioxide and aqueous solutions of calcium hydroxide. The design parameters for gas-liquid phase are flow regime, individual mass transfer, gas-liquid specific interfacial area. Most studies on gas-liquid phase were devoted to the experimental determination of some of these parameters, and more specifically, of the mass transfer coefficient, kLa which depends fundamentally on the superficial gas velocity and on the physical properties of absorption phase. The principle investigation was directed to study the effect of the vibration on the mass transfer coefficient kLa in gas-liquid phase during absorption of CO2 in the in aqueous solution of calcium hydroxide. The vibration with a higher frequency increase the mass transfer coefficient kLa, but vibration with lower frequency didn-t improve it, the mass transfer coefficient kLa increase with increase the superficial gas velocity.

**Keywords:**
Environment technology,
mass transfer coefficient,
absorption,
CO2,
calcium hydroxide.