From theoretical and experimental considerations the influence of the concentrator mass on the op... more From theoretical and experimental considerations the influence of the concentrator mass on the operation of the magnetostrictive vibrator are considered with a view to the design and construction of an acoustical concentrator. The work is principally concerned with the mechanical force field appearing in the concentrator. From this analysis follows the selection of the material required for the concentrator which is programme tested on a computer. The calculated concentrator frequency is only approximate and to achieve optimum efficiency the system will require specific tuning.
The problems that are raised for an ultra acoustic system they can be solved by using an analytic... more The problems that are raised for an ultra acoustic system they can be solved by using an analytic modeling or finite element modeling. because the analytic method is extremely complicated and less more efficient in the project state it was applied the modeling using the method of finite element which has the following advantages: it allows the rapid determination of the vibration mode and the behavior of the system at different frequencies, it allows the ready-made determination of the tension and deformation state in each section of the system, determines the vibration diagram of the amplitude velocity of the particle in each point of the system which vibrates even in his active part. In the work there are presented the results obtained by modeling with finite element method of the ultra acoustic system, movement amplifier-bell concentrator used at the ultrasound welding of the signal auto lights.
This paper presents the main factors that cause environmental pollution in the case of the weldin... more This paper presents the main factors that cause environmental pollution in the case of the welding procedure in a protective gas environment. In the research the MIG and MAG welding processes were taken into account. The materials used in the experiments were 8TiCr170 stainless steel as the base material and as fi ller materials 4 types of welding wires were used, characterized by diff erent chemical compositions. To assess the impact on the work environment of such welding processes the pollution coeffi cient C p was defi ned based on the material balance equation as the ratio of the mass of all materials used in the welding process M t and the eff ective mass of the welded performed M u .
Paper presents the calculus elements and construction for the ultrasonic system used in reconditi... more Paper presents the calculus elements and construction for the ultrasonic system used in reconditioning process by metallization. A series of necessary elements used in ultrasonic system dimensioning are given and an ultrasonic system used in reconditioning process by plasma and grain metallization are presented. Also, a calculated ultrasonic system is modelled to work in resonance regime at the frequency f = 22Khz. Stress map inside material, internal energy variation, lost energy variation on length and volume unit are presented.
In the presented paper experimental results on welding polystyrene and optical elements are shown... more In the presented paper experimental results on welding polystyrene and optical elements are shown. On the basis of the obtained results on shearing-stretching and macroscopic analysis of the work pieces, conclusions are drawn regarding the weld when using ultrasonic welding process.
The article presents resarches for designing and manufacturing of the ultrasonic motors that uses... more The article presents resarches for designing and manufacturing of the ultrasonic motors that uses piezoceramic materials. There are presented specific vibrations modes for the studied piezoceramic plates, vibrations that are used to excite the motor activated element (mobile element). Using the finite element method it is really posssible to predict the usefull vibrations that can makes easier the design
In this paper, the application of an X-ray image segmentation algorithm based on a Competitive Ho... more In this paper, the application of an X-ray image segmentation algorithm based on a Competitive Hopfield Neural Network (CHNN) model for evaluating the insertion accuracy of pedicle screws is presented. In practice, the evaluation of pedicle screw insertion accuracy is made visually in two planes and is based on postoperative computer tomography scans or radiography. In order to increase the reliability of the assessment, this research proposes a new approach that automates this process and can be used for developing a training system for pedicle screw implantation. The proposed approach implements a training method which allows extracting features of the pedicle screw from X-ray images segmented using a modified HNN algorithm, and compares them with values from a knowledge database.
This paper presents the main technological procedures applicable in automotive reconditioning and... more This paper presents the main technological procedures applicable in automotive reconditioning and areas of application. It then makes a critical analysis of their function: the thickness of the deposited layer; reconditioning costs by loading operation; deposition rates of filler material, porosity layers deposited by different procedures of loading; areas of surface deformation temperatures and loaded; functional characteristics of the couple resulting from reconditioning. The paper presents a series of selection criteria used in the process of reconditioning repair of auto parts.
The finite element analysis method appears as a consequence of the need to calculate the complex ... more The finite element analysis method appears as a consequence of the need to calculate the complex structures, such as ultrasonic transducers and systems ultraacustic cleaning, for which analytical methods of calculation are not operable. The basic idea is that if the structure is divided into parts called finite elements, for each of those parts can be applied calculation methods corresponding to adopted schema. Dividing the whole into smaller parts, that is called mesh, will lead to the production of simple shapes for finite elements.
Professional risk evaluation represents a complex activity involving each economic operator, with... more Professional risk evaluation represents a complex activity involving each economic operator, with important repercussion upon health and security in work. Article represents an innovative study method, regarding professional risk analyze in which cumulative working posts are evaluated. Work presents a new software that helps in putting together all the working positions from a complex organizational system and analyzing them in order to evaluate the possible risks. Using this software, a multiple analysis can be done like: risk estimation, risk evaluation, estimation of residual risks and finally searching of risk reduction measures.
The paper presents the objective function of metal spraying process and optimizing its ultrasonic... more The paper presents the objective function of metal spraying process and optimizing its ultrasonic field. For CCR objective function, named quality function of resulted couple, were taken into account the following factors: resistance to adhesion surface; porosity; tensile strength; wear resistance; hardness of the material from couple; grain size of the deposited layer and the state of internal tension. To determine the function there are required numerous experiments using different metallization regimes, then placing the condition that it needs to have a maximum that is found among first-order derivative solutions of the objective function.
The fi llet welded structures, fatigue stressed, must have a concave shape in cross section and a... more The fi llet welded structures, fatigue stressed, must have a concave shape in cross section and a smooth transition between weldseamand base material, without stress concentrators. In this issue for the welded structures with convex fi llet welds, to improve the behavior in case of fatigue loads it will be necessary to apply rehabilitation techniques like toe grinding or WIG remelting. The paper wants to present the infl uence of that two rehabilitation technique and the behavior of the rehabilitated welded structures in case of static and dynamic loads.
This paper presents research conducted on the contents of fumes resulting from welding processes ... more This paper presents research conducted on the contents of fumes resulting from welding processes with emphasis on micro various metallic and nonmetallic elements involved in these fumes. It also presents the main health effects of welders and operators working in the welding stations. Are risks that may occur due to micro chromium, nickel, iron, manganese, silicon, fluorine, zinc, aluminum, copper, cadmium, lead, molybdenum, cobalt, vanadium and others.
The researches presented in the paper refer to the eff ect of ultrasounds propagation in the liqu... more The researches presented in the paper refer to the eff ect of ultrasounds propagation in the liquid metal bath on the process of transferring the additive material through the electric arch and on the crystallization process, and all these eff ects are analyzed for loaded welded parts solicited at the abrasive wear. All these infl uences are conferred to these two basic phenomena due to the ultrasounds propagation in liquid environments, namely, ultra-acoustic cavitation and acceleration of the diff usion process. The results concerns the resistance to the wear obtained for the loaded parts through manual welding with electric arch and classically covered electrode and ultrasonically activated.
Paper presents a new reconditioning method based on ultrasonic field and analyses the modificated... more Paper presents a new reconditioning method based on ultrasonic field and analyses the modificated structure composition in three zone: filler material, thermal influenced zone, and base material. Also, chemical composition variation as a result of ultrasonic wave influence is studied besides the ultrasonic wave influence on dilution process.
From theoretical and experimental considerations the influence of the concentrator mass on the op... more From theoretical and experimental considerations the influence of the concentrator mass on the operation of the magnetostrictive vibrator are considered with a view to the design and construction of an acoustical concentrator. The work is principally concerned with the mechanical force field appearing in the concentrator. From this analysis follows the selection of the material required for the concentrator which is programme tested on a computer. The calculated concentrator frequency is only approximate and to achieve optimum efficiency the system will require specific tuning.
The problems that are raised for an ultra acoustic system they can be solved by using an analytic... more The problems that are raised for an ultra acoustic system they can be solved by using an analytic modeling or finite element modeling. because the analytic method is extremely complicated and less more efficient in the project state it was applied the modeling using the method of finite element which has the following advantages: it allows the rapid determination of the vibration mode and the behavior of the system at different frequencies, it allows the ready-made determination of the tension and deformation state in each section of the system, determines the vibration diagram of the amplitude velocity of the particle in each point of the system which vibrates even in his active part. In the work there are presented the results obtained by modeling with finite element method of the ultra acoustic system, movement amplifier-bell concentrator used at the ultrasound welding of the signal auto lights.
This paper presents the main factors that cause environmental pollution in the case of the weldin... more This paper presents the main factors that cause environmental pollution in the case of the welding procedure in a protective gas environment. In the research the MIG and MAG welding processes were taken into account. The materials used in the experiments were 8TiCr170 stainless steel as the base material and as fi ller materials 4 types of welding wires were used, characterized by diff erent chemical compositions. To assess the impact on the work environment of such welding processes the pollution coeffi cient C p was defi ned based on the material balance equation as the ratio of the mass of all materials used in the welding process M t and the eff ective mass of the welded performed M u .
Paper presents the calculus elements and construction for the ultrasonic system used in reconditi... more Paper presents the calculus elements and construction for the ultrasonic system used in reconditioning process by metallization. A series of necessary elements used in ultrasonic system dimensioning are given and an ultrasonic system used in reconditioning process by plasma and grain metallization are presented. Also, a calculated ultrasonic system is modelled to work in resonance regime at the frequency f = 22Khz. Stress map inside material, internal energy variation, lost energy variation on length and volume unit are presented.
In the presented paper experimental results on welding polystyrene and optical elements are shown... more In the presented paper experimental results on welding polystyrene and optical elements are shown. On the basis of the obtained results on shearing-stretching and macroscopic analysis of the work pieces, conclusions are drawn regarding the weld when using ultrasonic welding process.
The article presents resarches for designing and manufacturing of the ultrasonic motors that uses... more The article presents resarches for designing and manufacturing of the ultrasonic motors that uses piezoceramic materials. There are presented specific vibrations modes for the studied piezoceramic plates, vibrations that are used to excite the motor activated element (mobile element). Using the finite element method it is really posssible to predict the usefull vibrations that can makes easier the design
In this paper, the application of an X-ray image segmentation algorithm based on a Competitive Ho... more In this paper, the application of an X-ray image segmentation algorithm based on a Competitive Hopfield Neural Network (CHNN) model for evaluating the insertion accuracy of pedicle screws is presented. In practice, the evaluation of pedicle screw insertion accuracy is made visually in two planes and is based on postoperative computer tomography scans or radiography. In order to increase the reliability of the assessment, this research proposes a new approach that automates this process and can be used for developing a training system for pedicle screw implantation. The proposed approach implements a training method which allows extracting features of the pedicle screw from X-ray images segmented using a modified HNN algorithm, and compares them with values from a knowledge database.
This paper presents the main technological procedures applicable in automotive reconditioning and... more This paper presents the main technological procedures applicable in automotive reconditioning and areas of application. It then makes a critical analysis of their function: the thickness of the deposited layer; reconditioning costs by loading operation; deposition rates of filler material, porosity layers deposited by different procedures of loading; areas of surface deformation temperatures and loaded; functional characteristics of the couple resulting from reconditioning. The paper presents a series of selection criteria used in the process of reconditioning repair of auto parts.
The finite element analysis method appears as a consequence of the need to calculate the complex ... more The finite element analysis method appears as a consequence of the need to calculate the complex structures, such as ultrasonic transducers and systems ultraacustic cleaning, for which analytical methods of calculation are not operable. The basic idea is that if the structure is divided into parts called finite elements, for each of those parts can be applied calculation methods corresponding to adopted schema. Dividing the whole into smaller parts, that is called mesh, will lead to the production of simple shapes for finite elements.
Professional risk evaluation represents a complex activity involving each economic operator, with... more Professional risk evaluation represents a complex activity involving each economic operator, with important repercussion upon health and security in work. Article represents an innovative study method, regarding professional risk analyze in which cumulative working posts are evaluated. Work presents a new software that helps in putting together all the working positions from a complex organizational system and analyzing them in order to evaluate the possible risks. Using this software, a multiple analysis can be done like: risk estimation, risk evaluation, estimation of residual risks and finally searching of risk reduction measures.
The paper presents the objective function of metal spraying process and optimizing its ultrasonic... more The paper presents the objective function of metal spraying process and optimizing its ultrasonic field. For CCR objective function, named quality function of resulted couple, were taken into account the following factors: resistance to adhesion surface; porosity; tensile strength; wear resistance; hardness of the material from couple; grain size of the deposited layer and the state of internal tension. To determine the function there are required numerous experiments using different metallization regimes, then placing the condition that it needs to have a maximum that is found among first-order derivative solutions of the objective function.
The fi llet welded structures, fatigue stressed, must have a concave shape in cross section and a... more The fi llet welded structures, fatigue stressed, must have a concave shape in cross section and a smooth transition between weldseamand base material, without stress concentrators. In this issue for the welded structures with convex fi llet welds, to improve the behavior in case of fatigue loads it will be necessary to apply rehabilitation techniques like toe grinding or WIG remelting. The paper wants to present the infl uence of that two rehabilitation technique and the behavior of the rehabilitated welded structures in case of static and dynamic loads.
This paper presents research conducted on the contents of fumes resulting from welding processes ... more This paper presents research conducted on the contents of fumes resulting from welding processes with emphasis on micro various metallic and nonmetallic elements involved in these fumes. It also presents the main health effects of welders and operators working in the welding stations. Are risks that may occur due to micro chromium, nickel, iron, manganese, silicon, fluorine, zinc, aluminum, copper, cadmium, lead, molybdenum, cobalt, vanadium and others.
The researches presented in the paper refer to the eff ect of ultrasounds propagation in the liqu... more The researches presented in the paper refer to the eff ect of ultrasounds propagation in the liquid metal bath on the process of transferring the additive material through the electric arch and on the crystallization process, and all these eff ects are analyzed for loaded welded parts solicited at the abrasive wear. All these infl uences are conferred to these two basic phenomena due to the ultrasounds propagation in liquid environments, namely, ultra-acoustic cavitation and acceleration of the diff usion process. The results concerns the resistance to the wear obtained for the loaded parts through manual welding with electric arch and classically covered electrode and ultrasonically activated.
Paper presents a new reconditioning method based on ultrasonic field and analyses the modificated... more Paper presents a new reconditioning method based on ultrasonic field and analyses the modificated structure composition in three zone: filler material, thermal influenced zone, and base material. Also, chemical composition variation as a result of ultrasonic wave influence is studied besides the ultrasonic wave influence on dilution process.
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Papers by Gheorghe Amza