The objective of this investigation was to study the fatigue behaviour of pig jaw compact bone ma... more The objective of this investigation was to study the fatigue behaviour of pig jaw compact bone material specimens subjected to compression tests. Samples for experiments were prepared from three 2 years old pig lower jaws. Specimens were tested under cyclic load with peak load levels that were 60 %, 70 %, 80 %, and 90 % of the compressive yield strength with a frequency of 2 Hz. Fatigue tests of pig jaw cortical bone in compression were conducted and results were summarized as peak stress versus cycles. Experimental data were approximated using reversed power function. The fatigue properties of cortical bone determined in this study were compared with previous studies from the literature
The mandible from the structural mechanics point of view at the macroscopic level is a highly com... more The mandible from the structural mechanics point of view at the macroscopic level is a highly complex composite material which exhibits viscoelastic, a time-dependent behaviour. The lack of specific experimental data of the human jaw bone tissue prevents the implementation of these properties into finite element simulation which results in poor quality modelling. The objective of this investigation was to study the short-term creep behaviour of human jaw compact bone material specimens subjected to compression tests. This paper deals with both experimental determination of active creep and approximation of the obtained results using exponential function. Samples for experiments were prepared from five 49 – 56 years old male lower jaws obtained in autopsy. The creep strains were determined for 15 specimens in a specially designed equipment. The experimental creep strains of the human mandible compact bone material were approximated for each sample separately and for group of samples....
The lack of lecture hours in the curriculum of the subject requires students to study the theoret... more The lack of lecture hours in the curriculum of the subject requires students to study the theoretical material independently; it’s difficult for understanding of and skills mastering of the graphical subjects. In given article the example of interactive multimedia theoretical and instructional applications for study of compulsory subject “Descriptive Geometry and Engineering Graphics” and for free choice subjects “Interactive Computer Graphics” and “Computer Aided Design” for first and second year students of the Riga Technical University (RTU) are presented. The multimedia lectures will facilitate the understanding of difficult themes of subject “Descriptive Geometry and Engineering Graphics” resulting in improved student learning
«Is the Manual drawing is still used in engineering education nowadays?» - actual question which ... more «Is the Manual drawing is still used in engineering education nowadays?» - actual question which often meets at students’ forums. The proper estimation of computer technologies is very important when computers are to be implemented in the educational process. Otherwise, if not implemented properly, the quality of students' education may be seriously imperiled. In this paper we, propose how and to which extent the computerization of education process should be carried out and a necessity of the manual drawings’ use for study of compulsory subject “Civil Engineering” for Civil engineering undergraduate 2nd year students of Riga Technical university is considered. Definition of ratio of manual drawings and drawings with CAD software use, as a part of curricula, is a prominent aspect of quality of educational process and motivation of modern students
In the given article the examples of application of learning management system and interactive wh... more In the given article the examples of application of learning management system and interactive whiteboard in the teaching of subject “Descriptive Geometry and Engineering Graphics” are presented. This paper starts by describing our experience in using the learning management system. The learning management system was exploited for study of compulsory subject for students of the Riga Technical University (RTU). In addition the Blackboard Learning System (BB) was used for accommodation of a teaching material. The next section deals with a very important area in which the introduction of information communication technologies (ICT) has the potential to revolutionize teaching habits. In given article the example of a lecture material for a theme “A Plane” using interactive whiteboard is presented. Experiences in using ICT in actual training confirmed the potential of interactive whiteboard as a beneficial and usable system for teaching. Students’ feedback was very positive, and it is clear that use of ICT in education will emerge as a real option at the university level
The article focuses on the issue of ISO and EU standards adapted in Latvia and corresponding to E... more The article focuses on the issue of ISO and EU standards adapted in Latvia and corresponding to ESKD 3rd group standards in terms of contents. These standards deal with regulations on technical drawings making the basis of the subject of “Engineering Graphics”. The article provides a historic insight on the development of Latvian standardisation institutions, their tasks and organisational structure. Also, the article analyses the situation in the area of publishing study literature developed according to Latvian standards
In the given article the examples of application of Moodle learning management system in the teac... more In the given article the examples of application of Moodle learning management system in the teaching of subjects at the Department of Computer Aided Engineering Graphics of the Riga Technical University (RTU) are presented. This paper starts by ...
Recent developments in computer technology and the availability of digital databases have made it... more Recent developments in computer technology and the availability of digital databases have made it much easier to generate landscape visualizations that can be used to support decision making on urban planning. Computer technology, computer graphics, ...
The proper estimation of computer technologies is very important when computers are to be impleme... more The proper estimation of computer technologies is very important when computers are to be implemented in the educational process. Nowadays, there is a tendency of computerisation of graphical subjects, using various CAD programs. Unfortunately, use of CAD programs, in education process, without manual drawing preparation, show significant problems in formation of faculties for spatial abilities of students. In this paper we, propose how and to which extent the computerisation of compulsory subject “Civil Engineering Drawing” for Civil engineering undergraduate 2nd year students of Riga Technical University should be carried out
Paper deals with a problem on how to raise an interest to the students during preparation for pra... more Paper deals with a problem on how to raise an interest to the students during preparation for practical training exercises and individual home assignments in the course of Descriptive Geometry and Engineering Graphics. The methods of teaching used for the decades should be reviewed taking into account a new generation of students, their habits of learning and the existing challenges provided by contemporary information technologies. An attempt was made to create new educational materials which would motivate the students to work autonomously with the theoretical materials. An Augmented Reality (AR) based applications were used to entertain the students during the studies of the development of spatial reasoning in the first year studies. The efficiency of the regular tests on understanding the theoretical issues of descriptive geometry and engineering graphics was evaluated. For this purpose a portal ORTUS of Riga Technical University (RTU) was used. ORTUS – a multifunctional educati...
Mācību līdzeklis ir paredzēts mācību priekšmeta "Tēlotāja ģeometrija un inženiergrafika"... more Mācību līdzeklis ir paredzēts mācību priekšmeta "Tēlotāja ģeometrija un inženiergrafika"apguvei RTU studiju programmu ietvaros un tas satur teorētisku materiālu un praktiskus piemērus par būvniecības rasējumu noformēšanu saskaņā ar Eiropas valstīs lietojamiem ISO ( starptautiskajiem) un EN (Eiropas) standartiem
Darbā pētīta cilvēka apakšžokļa kompakto kaulaudu aktīvā šļūde ilglaicīgās statiskās spiedes eksp... more Darbā pētīta cilvēka apakšžokļa kompakto kaulaudu aktīvā šļūde ilglaicīgās statiskās spiedes eksperimentā. Paraugi iegūti no pieciem 49 līdz 56 gadu vecu cilvēku apakšžokļiem. Eksperimentu rezultātā noteiktas šļūdes deformācijas, kuru lielums ir atkarīgs no parauga lokalizācijas un sprieguma. Šļūdes deformācijas eksperimentālie dati 15 paraugiem tika aproksimēti ar eksponenciālo funkciju divos variantos – ar divām un trim eksponentēm, katram paraugam atsevišķi. Novērtējot iegūtos rezultātus, atmesti paraugi ar krasi atšķirīgiem datiem, ko var saistīt ar mehānisko un bioloģisko faktoru ietekmi. Aproksimējot paraugu grupu ar divām un trim eksponentēm un kopējām šļūdes vienādojuma konstantēm, labi rezultāti tika iegūti 5 paraugiem. Iegūtos rezultātus var izmantot apakšžokļa kaula matemātiskā modeļa izstrādāšanai, ar mērķi optimizēt un uzlabot ārstēšanas procesu
A satisfactory finite element analysis model of the human mandibular and dentition system besides... more A satisfactory finite element analysis model of the human mandibular and dentition system besides the detailed 3D geometry considers also static and time – dependent mechanical properties of different components of the jaw bone. The major role plays compact bone tissue. The aim of the work was to investigate the active creep of the compact part of human mandibular bone. Creep tests of 15 specimens were conducted at room temperature, with applied constant compressive stresses between 5 and 40.8 MPa. The obtained results were approximated with exponential function. Average values of the creep properties of human jaw compact bone tissue for 5 specimens group were achieved
Mācību līdzeklis paredzēts mācību priekšmeta “Tēlotāja ģeometrija un inženiergrafika” apguvei RTU... more Mācību līdzeklis paredzēts mācību priekšmeta “Tēlotāja ģeometrija un inženiergrafika” apguvei RTU studiju programmu ietvaros. Pirmā daļa satur teorētisku materiālu un praktiskus piemērus par telpisko objektu attēlošanu plaknē un telpā, dažādām konstrukcijām, izmantojot objektu attēlus un to modeļus. Otrajā daļā ir aplūkoti tehniskās rasēšanas pamati tā satur teorētisko materiālu un praktiskus piemērus par rasējumu noformēšanu saskaņā ar Eiropas valstīs lietotajiem ISO (starptautiskajiem), EN (Eiropas) un atsevišķos gadījumos arī GOST standartiem
During normal activities bone is subjected to variety of combined mechanical stresses. When bone ... more During normal activities bone is subjected to variety of combined mechanical stresses. When bone is subjected to a cyclical loading, within the bone tissue micro fractures occur which can accumulate with time. The combination of both the bone weakening effects caused by micro fractures accumulation and natural bone resorption can lead to severe stress fractures. Bending is a complex load application mode which takes place when a non-axial, offset force is applied, producing tension on one side and compression on the other. The purpose of present investigation is to describe the experimental research performed on physiologically wet bovine compact bone specimens in the cyclic three point bending test. Specimens in the form of rectangular beams (45 – 50)×(4 – 8)×(2 – 4) mm were machined from the mid-diaphysis of fresh one year old bovine femur. The first series of experiments were conducted with minimum cyclic stress level (σmin) from about 10 MPa to maximum cyclic stress level (σmax) less than 50 % of the ultimate flexural stress (σ*). The second series of experiments were carried out with σmin ≈ 0.5 σ* and σmax < σ*. The specimens were tested at room temperature 20 ± 2°C. Mechanical properties from experimental test data were calculated. The results indicate that relative cyclic strain range increases with increasing the number of loading cycles and this strain range increment has maximum in second load cycle, however relative cyclic strain range increase decreases for each consecutive load cycle. The values of mechanical properties of compact bone material depend also on the location of samples in bone cross section
The objective of this investigation was to study the fatigue behaviour of pig jaw compact bone ma... more The objective of this investigation was to study the fatigue behaviour of pig jaw compact bone material specimens subjected to compression tests. Samples for experiments were prepared from three 2 years old pig lower jaws. Specimens were tested under cyclic load with peak load levels that were 60 %, 70 %, 80 %, and 90 % of the compressive yield strength with a frequency of 2 Hz. Fatigue tests of pig jaw cortical bone in compression were conducted and results were summarized as peak stress versus cycles. Experimental data were approximated using reversed power function. The fatigue properties of cortical bone determined in this study were compared with previous studies from the literature
The mandible from the structural mechanics point of view at the macroscopic level is a highly com... more The mandible from the structural mechanics point of view at the macroscopic level is a highly complex composite material which exhibits viscoelastic, a time-dependent behaviour. The lack of specific experimental data of the human jaw bone tissue prevents the implementation of these properties into finite element simulation which results in poor quality modelling. The objective of this investigation was to study the short-term creep behaviour of human jaw compact bone material specimens subjected to compression tests. This paper deals with both experimental determination of active creep and approximation of the obtained results using exponential function. Samples for experiments were prepared from five 49 – 56 years old male lower jaws obtained in autopsy. The creep strains were determined for 15 specimens in a specially designed equipment. The experimental creep strains of the human mandible compact bone material were approximated for each sample separately and for group of samples....
The lack of lecture hours in the curriculum of the subject requires students to study the theoret... more The lack of lecture hours in the curriculum of the subject requires students to study the theoretical material independently; it’s difficult for understanding of and skills mastering of the graphical subjects. In given article the example of interactive multimedia theoretical and instructional applications for study of compulsory subject “Descriptive Geometry and Engineering Graphics” and for free choice subjects “Interactive Computer Graphics” and “Computer Aided Design” for first and second year students of the Riga Technical University (RTU) are presented. The multimedia lectures will facilitate the understanding of difficult themes of subject “Descriptive Geometry and Engineering Graphics” resulting in improved student learning
«Is the Manual drawing is still used in engineering education nowadays?» - actual question which ... more «Is the Manual drawing is still used in engineering education nowadays?» - actual question which often meets at students’ forums. The proper estimation of computer technologies is very important when computers are to be implemented in the educational process. Otherwise, if not implemented properly, the quality of students' education may be seriously imperiled. In this paper we, propose how and to which extent the computerization of education process should be carried out and a necessity of the manual drawings’ use for study of compulsory subject “Civil Engineering” for Civil engineering undergraduate 2nd year students of Riga Technical university is considered. Definition of ratio of manual drawings and drawings with CAD software use, as a part of curricula, is a prominent aspect of quality of educational process and motivation of modern students
In the given article the examples of application of learning management system and interactive wh... more In the given article the examples of application of learning management system and interactive whiteboard in the teaching of subject “Descriptive Geometry and Engineering Graphics” are presented. This paper starts by describing our experience in using the learning management system. The learning management system was exploited for study of compulsory subject for students of the Riga Technical University (RTU). In addition the Blackboard Learning System (BB) was used for accommodation of a teaching material. The next section deals with a very important area in which the introduction of information communication technologies (ICT) has the potential to revolutionize teaching habits. In given article the example of a lecture material for a theme “A Plane” using interactive whiteboard is presented. Experiences in using ICT in actual training confirmed the potential of interactive whiteboard as a beneficial and usable system for teaching. Students’ feedback was very positive, and it is clear that use of ICT in education will emerge as a real option at the university level
The article focuses on the issue of ISO and EU standards adapted in Latvia and corresponding to E... more The article focuses on the issue of ISO and EU standards adapted in Latvia and corresponding to ESKD 3rd group standards in terms of contents. These standards deal with regulations on technical drawings making the basis of the subject of “Engineering Graphics”. The article provides a historic insight on the development of Latvian standardisation institutions, their tasks and organisational structure. Also, the article analyses the situation in the area of publishing study literature developed according to Latvian standards
In the given article the examples of application of Moodle learning management system in the teac... more In the given article the examples of application of Moodle learning management system in the teaching of subjects at the Department of Computer Aided Engineering Graphics of the Riga Technical University (RTU) are presented. This paper starts by ...
Recent developments in computer technology and the availability of digital databases have made it... more Recent developments in computer technology and the availability of digital databases have made it much easier to generate landscape visualizations that can be used to support decision making on urban planning. Computer technology, computer graphics, ...
The proper estimation of computer technologies is very important when computers are to be impleme... more The proper estimation of computer technologies is very important when computers are to be implemented in the educational process. Nowadays, there is a tendency of computerisation of graphical subjects, using various CAD programs. Unfortunately, use of CAD programs, in education process, without manual drawing preparation, show significant problems in formation of faculties for spatial abilities of students. In this paper we, propose how and to which extent the computerisation of compulsory subject “Civil Engineering Drawing” for Civil engineering undergraduate 2nd year students of Riga Technical University should be carried out
Paper deals with a problem on how to raise an interest to the students during preparation for pra... more Paper deals with a problem on how to raise an interest to the students during preparation for practical training exercises and individual home assignments in the course of Descriptive Geometry and Engineering Graphics. The methods of teaching used for the decades should be reviewed taking into account a new generation of students, their habits of learning and the existing challenges provided by contemporary information technologies. An attempt was made to create new educational materials which would motivate the students to work autonomously with the theoretical materials. An Augmented Reality (AR) based applications were used to entertain the students during the studies of the development of spatial reasoning in the first year studies. The efficiency of the regular tests on understanding the theoretical issues of descriptive geometry and engineering graphics was evaluated. For this purpose a portal ORTUS of Riga Technical University (RTU) was used. ORTUS – a multifunctional educati...
Mācību līdzeklis ir paredzēts mācību priekšmeta "Tēlotāja ģeometrija un inženiergrafika"... more Mācību līdzeklis ir paredzēts mācību priekšmeta "Tēlotāja ģeometrija un inženiergrafika"apguvei RTU studiju programmu ietvaros un tas satur teorētisku materiālu un praktiskus piemērus par būvniecības rasējumu noformēšanu saskaņā ar Eiropas valstīs lietojamiem ISO ( starptautiskajiem) un EN (Eiropas) standartiem
Darbā pētīta cilvēka apakšžokļa kompakto kaulaudu aktīvā šļūde ilglaicīgās statiskās spiedes eksp... more Darbā pētīta cilvēka apakšžokļa kompakto kaulaudu aktīvā šļūde ilglaicīgās statiskās spiedes eksperimentā. Paraugi iegūti no pieciem 49 līdz 56 gadu vecu cilvēku apakšžokļiem. Eksperimentu rezultātā noteiktas šļūdes deformācijas, kuru lielums ir atkarīgs no parauga lokalizācijas un sprieguma. Šļūdes deformācijas eksperimentālie dati 15 paraugiem tika aproksimēti ar eksponenciālo funkciju divos variantos – ar divām un trim eksponentēm, katram paraugam atsevišķi. Novērtējot iegūtos rezultātus, atmesti paraugi ar krasi atšķirīgiem datiem, ko var saistīt ar mehānisko un bioloģisko faktoru ietekmi. Aproksimējot paraugu grupu ar divām un trim eksponentēm un kopējām šļūdes vienādojuma konstantēm, labi rezultāti tika iegūti 5 paraugiem. Iegūtos rezultātus var izmantot apakšžokļa kaula matemātiskā modeļa izstrādāšanai, ar mērķi optimizēt un uzlabot ārstēšanas procesu
A satisfactory finite element analysis model of the human mandibular and dentition system besides... more A satisfactory finite element analysis model of the human mandibular and dentition system besides the detailed 3D geometry considers also static and time – dependent mechanical properties of different components of the jaw bone. The major role plays compact bone tissue. The aim of the work was to investigate the active creep of the compact part of human mandibular bone. Creep tests of 15 specimens were conducted at room temperature, with applied constant compressive stresses between 5 and 40.8 MPa. The obtained results were approximated with exponential function. Average values of the creep properties of human jaw compact bone tissue for 5 specimens group were achieved
Mācību līdzeklis paredzēts mācību priekšmeta “Tēlotāja ģeometrija un inženiergrafika” apguvei RTU... more Mācību līdzeklis paredzēts mācību priekšmeta “Tēlotāja ģeometrija un inženiergrafika” apguvei RTU studiju programmu ietvaros. Pirmā daļa satur teorētisku materiālu un praktiskus piemērus par telpisko objektu attēlošanu plaknē un telpā, dažādām konstrukcijām, izmantojot objektu attēlus un to modeļus. Otrajā daļā ir aplūkoti tehniskās rasēšanas pamati tā satur teorētisko materiālu un praktiskus piemērus par rasējumu noformēšanu saskaņā ar Eiropas valstīs lietotajiem ISO (starptautiskajiem), EN (Eiropas) un atsevišķos gadījumos arī GOST standartiem
During normal activities bone is subjected to variety of combined mechanical stresses. When bone ... more During normal activities bone is subjected to variety of combined mechanical stresses. When bone is subjected to a cyclical loading, within the bone tissue micro fractures occur which can accumulate with time. The combination of both the bone weakening effects caused by micro fractures accumulation and natural bone resorption can lead to severe stress fractures. Bending is a complex load application mode which takes place when a non-axial, offset force is applied, producing tension on one side and compression on the other. The purpose of present investigation is to describe the experimental research performed on physiologically wet bovine compact bone specimens in the cyclic three point bending test. Specimens in the form of rectangular beams (45 – 50)×(4 – 8)×(2 – 4) mm were machined from the mid-diaphysis of fresh one year old bovine femur. The first series of experiments were conducted with minimum cyclic stress level (σmin) from about 10 MPa to maximum cyclic stress level (σmax) less than 50 % of the ultimate flexural stress (σ*). The second series of experiments were carried out with σmin ≈ 0.5 σ* and σmax < σ*. The specimens were tested at room temperature 20 ± 2°C. Mechanical properties from experimental test data were calculated. The results indicate that relative cyclic strain range increases with increasing the number of loading cycles and this strain range increment has maximum in second load cycle, however relative cyclic strain range increase decreases for each consecutive load cycle. The values of mechanical properties of compact bone material depend also on the location of samples in bone cross section
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