The widespread penetration of distributed energy sources and the use of load response programs,especially in a microgrid,have caused many power system issues,such as control and operation of these networks,to be affec...The widespread penetration of distributed energy sources and the use of load response programs,especially in a microgrid,have caused many power system issues,such as control and operation of these networks,to be affected.The control and operation of many small-distributed generation units with different performance characteristics create another challenge for the safe and efficient operation of the microgrid.In this paper,the optimum operation of distributed generation resources and heat and power storage in a microgrid,was performed based on real-time pricing through the proposed gray wolf optimization(GWO)algorithm to reduce the energy supply cost with the microgrid.Distributed generation resources such as solar panels,diesel generators with battery storage,and boiler thermal resources with thermal storage were used in the studied microgrid.Also,a combined heat and power(CHP)unit was used to produce thermal and electrical energy simultaneously.In the simulations,in addition to the gray wolf algorithm,some optimization algorithms have also been used.Then the results of 20 runs for each algorithm confirmed the high accuracy of the proposed GWO algorithm.The results of the simulations indicated that the CHP energy resources must be managed to have a minimum cost of energy supply in the microgrid,considering the demand response program.展开更多
This paper deals with the numerical implementation of the exponential Drucker-Parger plasticitymodel in the commercial finite element software,ABAQUS,via user subroutine UMAT for adhesive joint simulations.The influen...This paper deals with the numerical implementation of the exponential Drucker-Parger plasticitymodel in the commercial finite element software,ABAQUS,via user subroutine UMAT for adhesive joint simulations.The influence of hydrostatic pressure on adhesive strength was investigated by a modified Arcan fixture designed particularly to induce a different state of hydrostatic pressure within an adhesive layer.The developed user subroutine UMAT,which utilizes an associated plastic flow during a plastic deformation,can provide a good agreement between the simulations and the experimental data.Better numerical stability at highly positive hydrostatic pressure loads for a very high order of exponential function can also be achieved compared to when a non-associated flow is used.展开更多
The present study suggests that series voltage injection is more effective than parallel current injection to improve voltage quality on the load side.The line voltage can be accurately symmetrized at the connection p...The present study suggests that series voltage injection is more effective than parallel current injection to improve voltage quality on the load side.The line voltage can be accurately symmetrized at the connection point by creating and controlling a series voltage component in each phase.This is more reliable and effective than parallel current injection.A dynamic voltage restorer(DVR)and a distribution static synchronous compensator(DSTATCOM)were utilized to provide the required power.The DVR is an effective andmodern device utilized in parallel within the grid and can protect sensitive loads from voltage problems in the grid by injecting voltage.The DVR and D-STATCOM were used to improve voltage stability in faults.A standard 13-bus system was studied in the presence of a wind farm.The simulation results demonstrated that single and three-phase overloads dramatically altered the voltage of the system,making it necessary to use compensators to improve voltage stability.The DVR and D-STATCOM showed similar performance under normal conditions and somewhat improved grid voltage unbalance.However,the DVR outperformed D-STATCOM under asymmetric faults conditions and led to lower voltage variations.展开更多
The islanded mode is one of the connection modes of the grid distributed generation resources.In this study,a distributed generation resource is connected to linear and nonlinear loads via a three-phase inverter where...The islanded mode is one of the connection modes of the grid distributed generation resources.In this study,a distributed generation resource is connected to linear and nonlinear loads via a three-phase inverter where a control method needing no current sensors or compensator elements is applied to the distribute generation system in the islanded mode.This control method has two main loops in each phase.The first loop controls the voltage control loops that adjust the three-phase point of common coupling,the amplitude of the non-sinusoidal reference waveform and the near-state pulse width modulation(NSPWM)method.The next loop compensates the harmonic compensator loop that calculates the voltage harmonics of the point of common coupling in each phase,and injects them to compensate the non-sinusoidal reference waveforms of each phase.The simulation results in MATLAB/SIMULINK show that this method can generate balanced threephase sinusoidal voltage with an acceptable total harmonic distortion(THD)at the joint connection point.展开更多
With the daily expansion of global energy consumption,developing the power grids is of uttermost importance.However,building a new trans-mission line is costly and time-consuming,so utilizing the same lines with possi...With the daily expansion of global energy consumption,developing the power grids is of uttermost importance.However,building a new trans-mission line is costly and time-consuming,so utilizing the same lines with possible higher transmission capacity is very cost-effective.In this regard,to increase the capacity of the transmission lines,the flexible alternating current transmission system(FACTS)has been widely used in power grids in recent years by industrialized countries.One of the essential topics in electrical power systems is the reactive power compensation,and the FACTS plays a significant role in controlling the reactive power current in the power grid and the system voltage oscillations and stability.When a static synchronous compensator(STATCOM)is embedded in a power system to increase the bus voltage,a supplementary damping controller can be designed to enhance the system oscillation damping.Given the expansion of the grids in the power system,the complexity of their optimization and the extraordinary ability of the imperialist competitive algorithm(ICA)for solving such problems,in this paper,the ICA has been used to determine the optimal position and size of the FACTS devices.展开更多
The effects of cryogenic cooling on cutting forces in the milling process of AISI 304 stainless steel were investigated experimentally.Cryogenic cooling was achieved by spraying liquid nitrogen to tool,chips and mater...The effects of cryogenic cooling on cutting forces in the milling process of AISI 304 stainless steel were investigated experimentally.Cryogenic cooling was achieved by spraying liquid nitrogen to tool,chips and material interfaces using a pipe with an internal diameter of 1 mm;the flow rate of liquid nitrogen was 5.2 L/min;two cutting directions（climbing and conventional milling）,two machining conditions（dry and cryogenic cooling） and four cutting speeds（80,120,160 and 200 m/min） were used in the milling process.Cryogenic cooling and cutting speed are found to be effective on cutting forces.Cutting forces and torque in cryogenic milling are higher than those in dry milling.Cutting force is increased as the cutting speed is increased.Tool fritter around insert nose radius is the main problem of climb milling method in cryogenic cooling at low cutting speeds.展开更多
This paper presents a synthesis of current-mode PI, PD and PID controllers employing current controlled current differential buffer amplifiers (CCCDBAs). The features of these controllers are that: the output paramete...This paper presents a synthesis of current-mode PI, PD and PID controllers employing current controlled current differential buffer amplifiers (CCCDBAs). The features of these controllers are that: the output parameters can be electronically/independently controlled by adjusting corresponding bias currents in the proportional, integral, and deviation controllers;circuit description of the PID controller is simply formulated, it consists of four CCCDBAs cooperating with two grounded capacitors, and PI and PD controllers are composed of three CCCCDBAs and a grounded capacitor. Without any external resistor, the proposed circuits are very suitable to develop into integrated circuit architecture. The given results from the PSpice simulation agree well with the theoretical anticipation. The approximate power consumption in a closed loop control system consisting of the PI, PD and PID controller with low-pass filter passive plant are 4.03 mW, 4.85 mW and 5.71 mW, respectively, at ±1.5 V power supply voltages.展开更多
The mechanical and physical properties of concrete specimens obtained from replacing natural coarse aggregate with waste vehi- cle rubber tires at levels of 2vol%, 5vol%, 7vol%, and 10vol% were studied, and the corros...The mechanical and physical properties of concrete specimens obtained from replacing natural coarse aggregate with waste vehi- cle rubber tires at levels of 2vol%, 5vol%, 7vol%, and 10vol% were studied, and the corrosion behavior of reinforcing steels was investigated in these specimens. Corrosion rates were determined by measuring the galvanic current between steel-reinforced concrete specimens both with and without chloride addition. The change in electrode potential of reinforcing steels in these concrete specimens was measured daily for a period of 60 d in accordance with the testing method in ASTM C876. The results show that the use of waste vehicle tires in concrete instead of coarse aggregate decreases the mechanical strength of the specimens, and increases the corrosion rates of the reinforcing steels embedded in the concretes.展开更多
A new two stage detonation forming machine was developed and cylindrical aluminum cups were formed by using gas detonation forming technology. The forming process was analyzed with the explicit finite element method w...A new two stage detonation forming machine was developed and cylindrical aluminum cups were formed by using gas detonation forming technology. The forming process was analyzed with the explicit finite element method with various parameters and ANSYS/LS-DYNA software. Defects of wrinkling and rupture were predicted for some forming conditions. The strain and the thickness distribution results were in good agreement with the experimental results. It was seen that thinning and forming mainly take place during the one fourth of the time. The effects of detonation pressure and blank holding force on the deformation of the work pieces were discussed. The numerical results were compared with those obtained in the experiments.展开更多
Two dimensional equations of steady motion for third order fluids are expressed in a special coordinate system generated by the potential flow corresponding to an inviscid fluid. For the inviscid flow around an arbitr...Two dimensional equations of steady motion for third order fluids are expressed in a special coordinate system generated by the potential flow corresponding to an inviscid fluid. For the inviscid flow around an arbitrary object, the streamlines are the phi-coordinates and velocity potential lines are psi-coordinates which form an orthogonal curvilinear set of coordinates. The outcome, boundary layer equations, is then shown to be independent of the body shape immersed into the flow. As a first approximation,assumption that second grade terms are negligible compared to viscous and third grade terms. Second grade terms spoil scaling transformation which is only transformation leading to similarity solutions for third grade fluid. By using Lie group methods,infinitesimal generators of boundary layer equations are calculated. The equations are transformed into an ordinary differential system. Numerical solutions of outcoming nonlinear differential equations are found by using combination of a Runge-Kutta algorithm and shooting technique.展开更多
This paper presents four algorithms for QoSensing (4TQS) and routing on dynamics Wireless Sensor Networks. Since many types of researches held on QoSensing improvement in terms of coverage and connectivity enhancement...This paper presents four algorithms for QoSensing (4TQS) and routing on dynamics Wireless Sensor Networks. Since many types of researches held on QoSensing improvement in terms of coverage and connectivity enhancement. In a WSN with a density of 120 static and 30 mobile nodes, the major power-consuming activities are mobility and communication. Such power constraint has a great effect on the node activities and the same network. We analyzed the occurrence of coverage holes which is, regions inside the area of interest that are void of operational nodes for sensing and/or routing purposes. 4TQS method shows clustering phase through neuro-fuzzy based affinity propagation NFAP, sleep scheduling phase with ESLS algorithm and the assist of coverage enhancement phase in which HAHP is involved. Routing phase and connectivity metrics are improved with DTMR algorithm. Involvement of four efficient algorithms results in improved QoSensing in WSN. We analyzed our proposed method in both Star and Mesh topology in order to evaluate the QoSensing metrics in both topologies. Our method shows promising results in QoSensing metrics or performance in dynamics WSNs.展开更多
A 5G wireless system requests a high-performance compact antenna device.This research work aims to report the characterization and verification of the artificial magnetic conductor(AMC)metamaterial for a high-gain pla...A 5G wireless system requests a high-performance compact antenna device.This research work aims to report the characterization and verification of the artificial magnetic conductor(AMC)metamaterial for a high-gain planar antenna.The configuration is formed by a double-side structure on an intrinsic dielectric slab.The 2-D periodic pattern as an impedance surface is mounted on the top surface,whereas at the bottom surface the ground plane with an inductive narrow aperture source is embedded.The characteristic of the resonant transmission is illustrated based on the electromagnetic virtual object of the AMC resonant structure to reveal the unique property of a magnetic material response.The characteristics of the AMC metamaterial and the planar antenna synthesis are investigated and verified by experiment using a low-cost FR4 dielectric material.The directional antenna gain is obviously enhanced by guiding a primary field radiation.The loss effect in a dielectric slab is essentially studied having an influence on antenna radiation.The verification shows a peak of the antenna gain around 9.7 dB at broadside which is improved by 6.2 dB in comparison with the primary aperture antenna without the AMC structure.The thin antenna profile ofλ/37.5 is achieved at 10GHz for 5Gevolution.The emission property in an AMCstructure herein contributes to the development of a lowprofile and high-gain planar antenna for a compact wireless component.展开更多
This paper introduces a decagonal C-shaped complementary splitring resonator(CSRR)textile-based metamaterial(MTM).The overall size of the proposed sub-wavelength MTM unit cell is 0.28λ0×0.255λ0 at 3 GHz.Its sto...This paper introduces a decagonal C-shaped complementary splitring resonator(CSRR)textile-based metamaterial(MTM).The overall size of the proposed sub-wavelength MTM unit cell is 0.28λ0×0.255λ0 at 3 GHz.Its stopband behaviour was first studied prior analysing the negative index properties of the proposed MTM.It is worth noting that in this work a unique way the experiments were completed.For both simulations and measurements,the proposed MTM exhibited negative-permittivity and negative-refractive index characteristics with an average bandwidth of more than 3 GHz(considering 1.7 to 8.2 GHz as the measurements were carried out within this range).In simulations,the MTM exhibited negative-permittivity properties within the range of 1.7 to 7.52 GHz and 7.96 to 8.2 GHz;and negative-refractive index from 1.7 to 2.23 GHz and 2.33 to 5.09 GHz and 5.63 to 7.45 GHz.When measured from 1.7 to 8.2 GHz,negative-permittivity and negative-refractive index characteristics are exhibited throughout an average bandwidth of more than 3 GHz.Similarly,the transmission coefficient attained in simulations and measurements indicated about 3 GHz of bandwidth,from 1.7 to 3.88 GHz and from 6.68 to 7.4 GHz.The satisfactory agreement between simulations and experiments indicates the potential of the proposed MTM for microwave applications.展开更多
The inception of Wireless Sensor Networks (WSN) has brought convenience into many lives with uninterrupted wireless network. The nodes that transmit data consist of heterogeneous and battery equipped sensor nodes (SNs...The inception of Wireless Sensor Networks (WSN) has brought convenience into many lives with uninterrupted wireless network. The nodes that transmit data consist of heterogeneous and battery equipped sensor nodes (SNs) that are deployed randomly for network surveillance. To manage the random deployment of nodes, clustering algorithms are used with efficient routing protocols. This results in aggregation and dropping of redundant data packets that enables flawless data transmission from cluster nodes to Base Station (BS) via Cluster Heads (CHs). In this paper, a dynamic and multi-hop clustering and routing protocol for thorough behavior analysis is proposed, taking distance and energy into consideration. This forms a smooth routing path from the cluster nodes, CHs, Sub-CHs to the BS. On comparing proposed process with the existing system, experimental analysis shows a significant enhancement in the performance of network lifetime, with improved data aggregation, throughput, as the protocol showing deterministic behavior while traversing the network for data transmission, we name this protocol as Multi-hop Deterministic energy efficient Routing protocol (MDR).展开更多
This article presents an active-only current-mode universal biquad filter performing three standard functions: low-pass, high-pass and band-pass function, which can be readily modified to achieve the rest functions (b...This article presents an active-only current-mode universal biquad filter performing three standard functions: low-pass, high-pass and band-pass function, which can be readily modified to achieve the rest functions (band-stop and all-pass). The circuit principle is based on active-only circuit designed by using differentiators which are constructed from current controlled current conveyor transconductance amplifier (CCCCTA) cooperating with an internally frequency compensated operational amplifier (OA). The features of the circuit are that: the pole frequency and quality factor can be independently tuned via the input bias currents and it is ideally temperature-insensitive, its circuit description is very simple, consisting of 3 CCCCTAs and 2 operational amplifiers, and the proposed circuit is very appropriate for further developing into integrated circuit architecture. The PSpice simulation results are shown. The given results agree well with the theoretical anticipation.展开更多
The two dimensional equations of motions for the slowly flowing and heat transfer in second grade fluid are written in Cartesian coordinates neglecting the inertial terms. When the inertia terms are simply omitted fro...The two dimensional equations of motions for the slowly flowing and heat transfer in second grade fluid are written in Cartesian coordinates neglecting the inertial terms. When the inertia terms are simply omitted from the equations of motions the resulting solutions are valid approximately for Re1. This fact can also be deduced from the dimensionless form of the momentum and energy equations. By employing Lie group analysis, the symmetries of the equations are calculated. The Lie algebra consists of four finite parameter and one infinite parameter Lie group transformations, one being the scaling symmetry and the others being translations. Two different types of solutions are found using the symmetries. Using translations in x and y coordinates, an exponential type of exact solution is presented. For the scaling symmetry, the outcoming ordinary differential equations are more involved and only a series type of approximate solution is presented. Finally, some boundary value problems are discussed.展开更多
Mechanical and physical properties, such as tensile strength, elongation at break, modulus of elasticity, Shore D hardness, melt flow rate (MFR), and electrical and thermal conductivities of composites with high densi...Mechanical and physical properties, such as tensile strength, elongation at break, modulus of elasticity, Shore D hardness, melt flow rate (MFR), and electrical and thermal conductivities of composites with high density polyethylene matrix reinforced with Al powders were investigated experimentally. Measurements of the mechanical and physical properties were performed up to a reinforcing component concentration of 30% volume Al powder and compared with mathematical models from the literature. The obtained results have shown that experimental data were in good agreement with theoretical data. The ultimate tensile strength (UTS) and elongation at break decreased with increasing Al powder content, which was attributed to the intro-duction of discontinuities in the polymer structure, and modulus of elasticity increased with increasing Al content. The composite preparation conditions allowed the formation of a random distribution of metallic particles in the polymer matrix volume for system high density polyethylene-Al (HDPE-Al). There was a cluster formation of Al particles at higher Al contents in the polymer matrix. Electrical and thermal conductivity values of HDPE-Al composites were higher than pure HDPE values.展开更多
SAE1010 structural carbon steel,which has a low cost price and wide range of use in the construction industry,has been studied as dual phase （DP） steel subjected to appropriate heat treatment,and its mechanical prop...SAE1010 structural carbon steel,which has a low cost price and wide range of use in the construction industry,has been studied as dual phase （DP） steel subjected to appropriate heat treatment,and its mechanical properties have been investigated under various tempering conditions. Intercritical annealing heat treatment has been applied to the reinforcing steel in order to obtain DP steels with different martensite volume fraction. In addition,these DP steels have been tempered at 200,300 and 400 ℃ for 45 min and then cooled to the room temperature. Mechanical properties such as tensile strength,yield strength,reduction in cross-sectional area,total elongation,resilience modulus and toughness have been examined. Furthermore,fractographic examination has been done with scanning electron microscope （SEM） as well as metallographic examination of the steels. As a result of this study,it is found that mechanical properties of DP steel have changed according to the hardness and ratio of martensite phase. In addition,tensile strength,yield strength and resilience modulus of the steels have been reduced. In contrast,the total elongation,reduction of the cross-sectional area and toughness have been increased.展开更多
基金This work was supported in part by an International Research Partnership“Electrical Engineering—Thai French Research Center(EE-TFRC)”under the project framework of the Lorraine Universitéd’Excellence(LUE)in cooperation between Universitéde Lorraine and King Mongkut’s University of Technology North Bangkok and in part by the National Research Council of Thailand(NRCT)under Senior Research Scholar Program under Grant No.N42A640328.
文摘The widespread penetration of distributed energy sources and the use of load response programs,especially in a microgrid,have caused many power system issues,such as control and operation of these networks,to be affected.The control and operation of many small-distributed generation units with different performance characteristics create another challenge for the safe and efficient operation of the microgrid.In this paper,the optimum operation of distributed generation resources and heat and power storage in a microgrid,was performed based on real-time pricing through the proposed gray wolf optimization(GWO)algorithm to reduce the energy supply cost with the microgrid.Distributed generation resources such as solar panels,diesel generators with battery storage,and boiler thermal resources with thermal storage were used in the studied microgrid.Also,a combined heat and power(CHP)unit was used to produce thermal and electrical energy simultaneously.In the simulations,in addition to the gray wolf algorithm,some optimization algorithms have also been used.Then the results of 20 runs for each algorithm confirmed the high accuracy of the proposed GWO algorithm.The results of the simulations indicated that the CHP energy resources must be managed to have a minimum cost of energy supply in the microgrid,considering the demand response program.
基金funded by King Mongkut’s University of Technology North Bangkok.Contract No.KMUTNB-PHD-62-07.
文摘This paper deals with the numerical implementation of the exponential Drucker-Parger plasticitymodel in the commercial finite element software,ABAQUS,via user subroutine UMAT for adhesive joint simulations.The influence of hydrostatic pressure on adhesive strength was investigated by a modified Arcan fixture designed particularly to induce a different state of hydrostatic pressure within an adhesive layer.The developed user subroutine UMAT,which utilizes an associated plastic flow during a plastic deformation,can provide a good agreement between the simulations and the experimental data.Better numerical stability at highly positive hydrostatic pressure loads for a very high order of exponential function can also be achieved compared to when a non-associated flow is used.
基金International Research Partnership“Electrical Engineering-Thai French Research Center(EE-TFRC)”under the project framework of the Lorraine Universitéd’Excellence(LUE)in cooperation between Universitéde Lorraine and King Mongkut’s University of Technology North Bangkok and in part by the National Research Council of Thailand(NRCT)under Senior Research Scholar Program under Grant No.N42A640328National Science,Research and Innovation Fund(NSRF)under King Mongkut’s University of Technology North Bangkok under Grant No.KMUTNB-FF-65-20.
文摘The present study suggests that series voltage injection is more effective than parallel current injection to improve voltage quality on the load side.The line voltage can be accurately symmetrized at the connection point by creating and controlling a series voltage component in each phase.This is more reliable and effective than parallel current injection.A dynamic voltage restorer(DVR)and a distribution static synchronous compensator(DSTATCOM)were utilized to provide the required power.The DVR is an effective andmodern device utilized in parallel within the grid and can protect sensitive loads from voltage problems in the grid by injecting voltage.The DVR and D-STATCOM were used to improve voltage stability in faults.A standard 13-bus system was studied in the presence of a wind farm.The simulation results demonstrated that single and three-phase overloads dramatically altered the voltage of the system,making it necessary to use compensators to improve voltage stability.The DVR and D-STATCOM showed similar performance under normal conditions and somewhat improved grid voltage unbalance.However,the DVR outperformed D-STATCOM under asymmetric faults conditions and led to lower voltage variations.
基金International Research Partnership“Electrical Engineering-Thai French Research Center(EE-TFRC)”under the project framework of the Lorraine Universitéd’Excellence(LUE)in cooperation between Universitéde Lorraine and King Mongkut’s University of Technology North Bangkok and in part by the National Research Council of Thailand(NRCT)under Senior Research Scholar Program under Grant No.N42A640328National Science,Research and Innovation Fund(NSRF)under King Mongkut’s University of Technology North Bangkok under Grant No.KMUTNB-FF-65-20.
文摘The islanded mode is one of the connection modes of the grid distributed generation resources.In this study,a distributed generation resource is connected to linear and nonlinear loads via a three-phase inverter where a control method needing no current sensors or compensator elements is applied to the distribute generation system in the islanded mode.This control method has two main loops in each phase.The first loop controls the voltage control loops that adjust the three-phase point of common coupling,the amplitude of the non-sinusoidal reference waveform and the near-state pulse width modulation(NSPWM)method.The next loop compensates the harmonic compensator loop that calculates the voltage harmonics of the point of common coupling in each phase,and injects them to compensate the non-sinusoidal reference waveforms of each phase.The simulation results in MATLAB/SIMULINK show that this method can generate balanced threephase sinusoidal voltage with an acceptable total harmonic distortion(THD)at the joint connection point.
基金This work was supported in part by an International Research Partnership“Electrical Engineering-Thai French Research Center(EE-TFRC)”under the project framework of the Lorraine Universited’Excellence(LUE)in cooperation between Universitede Lorraine and King Mongkut’s University of Technology North Bangkok and in part by the National Research Council of Thailand(NRCT)under Senior Research Scholar Program under Grant No.N42A640328.
文摘With the daily expansion of global energy consumption,developing the power grids is of uttermost importance.However,building a new trans-mission line is costly and time-consuming,so utilizing the same lines with possible higher transmission capacity is very cost-effective.In this regard,to increase the capacity of the transmission lines,the flexible alternating current transmission system(FACTS)has been widely used in power grids in recent years by industrialized countries.One of the essential topics in electrical power systems is the reactive power compensation,and the FACTS plays a significant role in controlling the reactive power current in the power grid and the system voltage oscillations and stability.When a static synchronous compensator(STATCOM)is embedded in a power system to increase the bus voltage,a supplementary damping controller can be designed to enhance the system oscillation damping.Given the expansion of the grids in the power system,the complexity of their optimization and the extraordinary ability of the imperialist competitive algorithm(ICA)for solving such problems,in this paper,the ICA has been used to determine the optimal position and size of the FACTS devices.
基金the Scientific and Technological Research Council of Turkey(TUBITAK)for providing the financial support of the cryogenic machining project(Project No.106M473)
文摘The effects of cryogenic cooling on cutting forces in the milling process of AISI 304 stainless steel were investigated experimentally.Cryogenic cooling was achieved by spraying liquid nitrogen to tool,chips and material interfaces using a pipe with an internal diameter of 1 mm;the flow rate of liquid nitrogen was 5.2 L/min;two cutting directions（climbing and conventional milling）,two machining conditions（dry and cryogenic cooling） and four cutting speeds（80,120,160 and 200 m/min） were used in the milling process.Cryogenic cooling and cutting speed are found to be effective on cutting forces.Cutting forces and torque in cryogenic milling are higher than those in dry milling.Cutting force is increased as the cutting speed is increased.Tool fritter around insert nose radius is the main problem of climb milling method in cryogenic cooling at low cutting speeds.
文摘This paper presents a synthesis of current-mode PI, PD and PID controllers employing current controlled current differential buffer amplifiers (CCCDBAs). The features of these controllers are that: the output parameters can be electronically/independently controlled by adjusting corresponding bias currents in the proportional, integral, and deviation controllers;circuit description of the PID controller is simply formulated, it consists of four CCCDBAs cooperating with two grounded capacitors, and PI and PD controllers are composed of three CCCCDBAs and a grounded capacitor. Without any external resistor, the proposed circuits are very suitable to develop into integrated circuit architecture. The given results from the PSpice simulation agree well with the theoretical anticipation. The approximate power consumption in a closed loop control system consisting of the PI, PD and PID controller with low-pass filter passive plant are 4.03 mW, 4.85 mW and 5.71 mW, respectively, at ±1.5 V power supply voltages.
文摘The mechanical and physical properties of concrete specimens obtained from replacing natural coarse aggregate with waste vehi- cle rubber tires at levels of 2vol%, 5vol%, 7vol%, and 10vol% were studied, and the corrosion behavior of reinforcing steels was investigated in these specimens. Corrosion rates were determined by measuring the galvanic current between steel-reinforced concrete specimens both with and without chloride addition. The change in electrode potential of reinforcing steels in these concrete specimens was measured daily for a period of 60 d in accordance with the testing method in ASTM C876. The results show that the use of waste vehicle tires in concrete instead of coarse aggregate decreases the mechanical strength of the specimens, and increases the corrosion rates of the reinforcing steels embedded in the concretes.
文摘A new two stage detonation forming machine was developed and cylindrical aluminum cups were formed by using gas detonation forming technology. The forming process was analyzed with the explicit finite element method with various parameters and ANSYS/LS-DYNA software. Defects of wrinkling and rupture were predicted for some forming conditions. The strain and the thickness distribution results were in good agreement with the experimental results. It was seen that thinning and forming mainly take place during the one fourth of the time. The effects of detonation pressure and blank holding force on the deformation of the work pieces were discussed. The numerical results were compared with those obtained in the experiments.
文摘Two dimensional equations of steady motion for third order fluids are expressed in a special coordinate system generated by the potential flow corresponding to an inviscid fluid. For the inviscid flow around an arbitrary object, the streamlines are the phi-coordinates and velocity potential lines are psi-coordinates which form an orthogonal curvilinear set of coordinates. The outcome, boundary layer equations, is then shown to be independent of the body shape immersed into the flow. As a first approximation,assumption that second grade terms are negligible compared to viscous and third grade terms. Second grade terms spoil scaling transformation which is only transformation leading to similarity solutions for third grade fluid. By using Lie group methods,infinitesimal generators of boundary layer equations are calculated. The equations are transformed into an ordinary differential system. Numerical solutions of outcoming nonlinear differential equations are found by using combination of a Runge-Kutta algorithm and shooting technique.
文摘This paper presents four algorithms for QoSensing (4TQS) and routing on dynamics Wireless Sensor Networks. Since many types of researches held on QoSensing improvement in terms of coverage and connectivity enhancement. In a WSN with a density of 120 static and 30 mobile nodes, the major power-consuming activities are mobility and communication. Such power constraint has a great effect on the node activities and the same network. We analyzed the occurrence of coverage holes which is, regions inside the area of interest that are void of operational nodes for sensing and/or routing purposes. 4TQS method shows clustering phase through neuro-fuzzy based affinity propagation NFAP, sleep scheduling phase with ESLS algorithm and the assist of coverage enhancement phase in which HAHP is involved. Routing phase and connectivity metrics are improved with DTMR algorithm. Involvement of four efficient algorithms results in improved QoSensing in WSN. We analyzed our proposed method in both Star and Mesh topology in order to evaluate the QoSensing metrics in both topologies. Our method shows promising results in QoSensing metrics or performance in dynamics WSNs.
基金funded by National Science,Research and Innovation Fund(NSRF)King Mongkut’s University of Technology North Bangkok with Contract No.KMUTNB-FF-65-26.
文摘A 5G wireless system requests a high-performance compact antenna device.This research work aims to report the characterization and verification of the artificial magnetic conductor(AMC)metamaterial for a high-gain planar antenna.The configuration is formed by a double-side structure on an intrinsic dielectric slab.The 2-D periodic pattern as an impedance surface is mounted on the top surface,whereas at the bottom surface the ground plane with an inductive narrow aperture source is embedded.The characteristic of the resonant transmission is illustrated based on the electromagnetic virtual object of the AMC resonant structure to reveal the unique property of a magnetic material response.The characteristics of the AMC metamaterial and the planar antenna synthesis are investigated and verified by experiment using a low-cost FR4 dielectric material.The directional antenna gain is obviously enhanced by guiding a primary field radiation.The loss effect in a dielectric slab is essentially studied having an influence on antenna radiation.The verification shows a peak of the antenna gain around 9.7 dB at broadside which is improved by 6.2 dB in comparison with the primary aperture antenna without the AMC structure.The thin antenna profile ofλ/37.5 is achieved at 10GHz for 5Gevolution.The emission property in an AMCstructure herein contributes to the development of a lowprofile and high-gain planar antenna for a compact wireless component.
基金This work was supported in part by the King Mongkut’s University of Technology North Bangkok(Grant no:KMUTNB-64-KNOW-12)in part by the by the Academy of Finland 6Genesis Flagship(Grant no:318927).
文摘This paper introduces a decagonal C-shaped complementary splitring resonator(CSRR)textile-based metamaterial(MTM).The overall size of the proposed sub-wavelength MTM unit cell is 0.28λ0×0.255λ0 at 3 GHz.Its stopband behaviour was first studied prior analysing the negative index properties of the proposed MTM.It is worth noting that in this work a unique way the experiments were completed.For both simulations and measurements,the proposed MTM exhibited negative-permittivity and negative-refractive index characteristics with an average bandwidth of more than 3 GHz(considering 1.7 to 8.2 GHz as the measurements were carried out within this range).In simulations,the MTM exhibited negative-permittivity properties within the range of 1.7 to 7.52 GHz and 7.96 to 8.2 GHz;and negative-refractive index from 1.7 to 2.23 GHz and 2.33 to 5.09 GHz and 5.63 to 7.45 GHz.When measured from 1.7 to 8.2 GHz,negative-permittivity and negative-refractive index characteristics are exhibited throughout an average bandwidth of more than 3 GHz.Similarly,the transmission coefficient attained in simulations and measurements indicated about 3 GHz of bandwidth,from 1.7 to 3.88 GHz and from 6.68 to 7.4 GHz.The satisfactory agreement between simulations and experiments indicates the potential of the proposed MTM for microwave applications.
文摘The inception of Wireless Sensor Networks (WSN) has brought convenience into many lives with uninterrupted wireless network. The nodes that transmit data consist of heterogeneous and battery equipped sensor nodes (SNs) that are deployed randomly for network surveillance. To manage the random deployment of nodes, clustering algorithms are used with efficient routing protocols. This results in aggregation and dropping of redundant data packets that enables flawless data transmission from cluster nodes to Base Station (BS) via Cluster Heads (CHs). In this paper, a dynamic and multi-hop clustering and routing protocol for thorough behavior analysis is proposed, taking distance and energy into consideration. This forms a smooth routing path from the cluster nodes, CHs, Sub-CHs to the BS. On comparing proposed process with the existing system, experimental analysis shows a significant enhancement in the performance of network lifetime, with improved data aggregation, throughput, as the protocol showing deterministic behavior while traversing the network for data transmission, we name this protocol as Multi-hop Deterministic energy efficient Routing protocol (MDR).
文摘This article presents an active-only current-mode universal biquad filter performing three standard functions: low-pass, high-pass and band-pass function, which can be readily modified to achieve the rest functions (band-stop and all-pass). The circuit principle is based on active-only circuit designed by using differentiators which are constructed from current controlled current conveyor transconductance amplifier (CCCCTA) cooperating with an internally frequency compensated operational amplifier (OA). The features of the circuit are that: the pole frequency and quality factor can be independently tuned via the input bias currents and it is ideally temperature-insensitive, its circuit description is very simple, consisting of 3 CCCCTAs and 2 operational amplifiers, and the proposed circuit is very appropriate for further developing into integrated circuit architecture. The PSpice simulation results are shown. The given results agree well with the theoretical anticipation.
文摘The two dimensional equations of motions for the slowly flowing and heat transfer in second grade fluid are written in Cartesian coordinates neglecting the inertial terms. When the inertia terms are simply omitted from the equations of motions the resulting solutions are valid approximately for Re1. This fact can also be deduced from the dimensionless form of the momentum and energy equations. By employing Lie group analysis, the symmetries of the equations are calculated. The Lie algebra consists of four finite parameter and one infinite parameter Lie group transformations, one being the scaling symmetry and the others being translations. Two different types of solutions are found using the symmetries. Using translations in x and y coordinates, an exponential type of exact solution is presented. For the scaling symmetry, the outcoming ordinary differential equations are more involved and only a series type of approximate solution is presented. Finally, some boundary value problems are discussed.
文摘Mechanical and physical properties, such as tensile strength, elongation at break, modulus of elasticity, Shore D hardness, melt flow rate (MFR), and electrical and thermal conductivities of composites with high density polyethylene matrix reinforced with Al powders were investigated experimentally. Measurements of the mechanical and physical properties were performed up to a reinforcing component concentration of 30% volume Al powder and compared with mathematical models from the literature. The obtained results have shown that experimental data were in good agreement with theoretical data. The ultimate tensile strength (UTS) and elongation at break decreased with increasing Al powder content, which was attributed to the intro-duction of discontinuities in the polymer structure, and modulus of elasticity increased with increasing Al content. The composite preparation conditions allowed the formation of a random distribution of metallic particles in the polymer matrix volume for system high density polyethylene-Al (HDPE-Al). There was a cluster formation of Al particles at higher Al contents in the polymer matrix. Electrical and thermal conductivity values of HDPE-Al composites were higher than pure HDPE values.
文摘SAE1010 structural carbon steel,which has a low cost price and wide range of use in the construction industry,has been studied as dual phase （DP） steel subjected to appropriate heat treatment,and its mechanical properties have been investigated under various tempering conditions. Intercritical annealing heat treatment has been applied to the reinforcing steel in order to obtain DP steels with different martensite volume fraction. In addition,these DP steels have been tempered at 200,300 and 400 ℃ for 45 min and then cooled to the room temperature. Mechanical properties such as tensile strength,yield strength,reduction in cross-sectional area,total elongation,resilience modulus and toughness have been examined. Furthermore,fractographic examination has been done with scanning electron microscope （SEM） as well as metallographic examination of the steels. As a result of this study,it is found that mechanical properties of DP steel have changed according to the hardness and ratio of martensite phase. In addition,tensile strength,yield strength and resilience modulus of the steels have been reduced. In contrast,the total elongation,reduction of the cross-sectional area and toughness have been increased.
