Pub Date : 2020-03-31DOI: 10.5604/01.3001.0014.2733
M. Owczarek
The knowledge of dynamic thermal properties of building elements is necessary to investigate temperature and heat flux changes in natural daily and annual cycles. The basic dynamic parameter is thermal diffusivity. A method for determining its value for real objects has been proposed. This method is based on measuring the temperature in the element’s volume and on assuming that the obtained results meet the Fourier equation. Validation by a numerical experiment was made. The wall of the building with known thermal parameters was assumed and the temperature distribution was calculated over time in the process of non-stationary heat exchange. From the results, the diffusivity value was calculated and compared with the data entered into the model. Validations were performed for several accuracy of the temperature value and for two forms of function which approximated the temperature values obtained from calculation. A preliminary analysis of errors has been carried out. Keywords: measurements of thermal diffusivity, temperature distribution in a building element, approximation, heat transfer
{"title":"Numerical validation of a method determining thermal diffusivity based on a measurement of a temperature profile","authors":"M. Owczarek","doi":"10.5604/01.3001.0014.2733","DOIUrl":"https://doi.org/10.5604/01.3001.0014.2733","url":null,"abstract":"The knowledge of dynamic thermal properties of building elements is necessary to investigate temperature and heat flux changes in natural daily and annual cycles. The basic dynamic parameter is thermal diffusivity. A method for determining its value for real objects has been proposed. This method is based on measuring the temperature in the element’s volume and on assuming that the obtained results meet the Fourier equation. Validation by a numerical experiment was made. The wall of the building with known thermal parameters was assumed and the temperature distribution was calculated over time in the process of non-stationary heat exchange. From the results, the diffusivity value was calculated and compared with the data entered into the model. Validations were performed for several accuracy of the temperature value and for two forms of function which approximated the temperature values obtained from calculation. A preliminary analysis of errors has been carried out.\u0000Keywords: measurements of thermal diffusivity, temperature distribution in a building element, approximation, heat transfer\u0000\u0000","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"69 1","pages":"15-21"},"PeriodicalIF":0.0,"publicationDate":"2020-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43090633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-31DOI: 10.5604/01.3001.0014.2791
A. Biernat, W. Przyborowski
The article presents a measuring system designed for a comprehensive experimental testing of various types of electric machines. These tests include measurements of electrical, electromagnetic, kinematic, as well as mechanical and thermal quantities. The basic measurements of electrical machines include currents and voltages in electrical circuits, including voltages on resistive and generally impedance elements of these circuits, and induced voltages. Depending on the machine class and type, the measured values are constant or change over time. Some magnitudes of electromagnetic transformations are measured in the area of machine construction. In addition, the parameters of the measured values of the type of signal discriminants (average, effective and maximum values) and their waveforms are presented. Due to the wide range of machine state parameters, i.e. its state variables - in different load states, the multiplicity of these signals and the need to know their different characteristics, it becomes necessary to use individually adopted signal processing subsystems, i.e. signal acquisition systems, in the measuring systems. It is now possible thanks to the development in the CAM (Computer Aided Measurement) programming, for example using the graphical programming language of the integrated LabVIEW system. The article also presents examples of subsystems for the acquisition of measurements of nonelectromagnetic signals like vibrational and acoustic ones generated in machines. Keywords: electric machines, measurements, measuring system
{"title":"Measuring system for comprehensive testing of electrical machines","authors":"A. Biernat, W. Przyborowski","doi":"10.5604/01.3001.0014.2791","DOIUrl":"https://doi.org/10.5604/01.3001.0014.2791","url":null,"abstract":"The article presents a measuring system designed for a comprehensive experimental testing\u0000of various types of electric machines. These tests include measurements of electrical, electromagnetic,\u0000kinematic, as well as mechanical and thermal quantities.\u0000The basic measurements of electrical machines include currents and voltages in electrical circuits,\u0000including voltages on resistive and generally impedance elements of these circuits, and induced voltages.\u0000Depending on the machine class and type, the measured values are constant or change over time. Some\u0000magnitudes of electromagnetic transformations are measured in the area of machine construction. In\u0000addition, the parameters of the measured values of the type of signal discriminants (average, effective\u0000and maximum values) and their waveforms are presented.\u0000Due to the wide range of machine state parameters, i.e. its state variables - in different load states, the\u0000multiplicity of these signals and the need to know their different characteristics, it becomes necessary to\u0000use individually adopted signal processing subsystems, i.e. signal acquisition systems, in the measuring\u0000systems. It is now possible thanks to the development in the CAM (Computer Aided Measurement)\u0000programming, for example using the graphical programming language of the integrated LabVIEW\u0000system. The article also presents examples of subsystems for the acquisition of measurements of nonelectromagnetic\u0000signals like vibrational and acoustic ones generated in machines.\u0000Keywords: electric machines, measurements, measuring system\u0000\u0000","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"69 1","pages":"35-56"},"PeriodicalIF":0.0,"publicationDate":"2020-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45894023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-02-28DOI: 10.5604/01.3001.0013.9735
P. Figoń
Most simulation packages provide long line models containing only two input terminals and two output terminals. These models allow testing transient states initiated by the occurrence of interference at the ends of the line. For this reason, it is not possible to study disorders occurring at any point of the electrical network. The article describes in detail the mathematical models of the long line, their implementation in the Matlab environment and exemplary results of computer simulations. Keywords: power line, state variables, differential scheme
{"title":"Mathematical models of single-phase long lines","authors":"P. Figoń","doi":"10.5604/01.3001.0013.9735","DOIUrl":"https://doi.org/10.5604/01.3001.0013.9735","url":null,"abstract":"Most simulation packages provide long line models containing only two input terminals and two output terminals. These models allow testing transient states initiated by the occurrence of interference at the ends of the line. For this reason, it is not possible to study disorders occurring at any point of the electrical network. The article describes in detail the mathematical models of the long line, their implementation in the Matlab environment and exemplary results of computer simulations.\u0000Keywords: power line, state variables, differential scheme\u0000\u0000","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71282396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-28DOI: 10.5604/01.3001.0013.3004
Olga Sulikowska, Aneta Brzuzy
The study presents information about the intelligent house system along with the justification of the thesis that this technology can be used in single-family houses. The general characteristics of the system are given, which include the history of the creation and the essence of operation. Attention has been paid to lower energy consumption due to the use of technology, which makes it easier for buildings to meet the requirements of the European Parliament Directive 2010. The article describes the most important sub-functions, such as lighting, heating or fire-protection subsystem. Based on the functional layout of a single-family home, the analysis of the most important types of the system was carried out. The study states that smart home systems can be used not only at the construction stage, but also in existing buildings, without the need for interference in the walls. Keywords: construction, modern technologies used in construction, smart home system.
{"title":"Smart home system — modern technology used in single-family housing","authors":"Olga Sulikowska, Aneta Brzuzy","doi":"10.5604/01.3001.0013.3004","DOIUrl":"https://doi.org/10.5604/01.3001.0013.3004","url":null,"abstract":"The study presents information about the intelligent house system along with the justification of the thesis that this technology can be used in single-family houses. The general characteristics of the system are given, which include the history of the creation and the essence of operation. Attention has been paid to lower energy consumption due to the use of technology, which makes it easier for buildings to meet the requirements of the European Parliament Directive 2010. The article describes the most important sub-functions, such as lighting, heating or fire-protection subsystem. Based on the functional layout of a single-family home, the analysis of the most important types of the system was carried out. The study states that smart home systems can be used not only at the construction stage, but also in existing buildings, without the need for interference in the walls.\u0000Keywords: construction, modern technologies used in construction, smart home system.\u0000\u0000","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71280667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-03-29DOI: 10.5604/01.3001.0013.1467
Przemysław Rodwald
The aim of the article is to present the password breaking methodology in case when an attacker (forensic investigator, court expert, pen tester) has imposed time restrictions. This is a typical situation during many legal investigations where computers are seized by legal authorities but they are protected by passwords. At the beginning, the current state of law in that matter is presented, along with good practices in seizing the evidence. Then, the ways of storing static passwords in information systems are showed, after which various classes of password breaking methods are reviewed (dictionary, brute-force, rule, combinator, mask, hybrid, etc.). The most popular tools supporting this process are listed as well. The main part of the paper presents the original strategy of conducting an attack on a single hashed password with time constraints. Costs as well as economic efficiency for four different hardware solutions (laptop, gaming computer, rig with 6 GPU’s, cloud computing) are discussed. The calculations are shown on the example of two real attacks carried out by the author in the real legal cases. Keywords: passwords, breaking passwords, hash functions, computer forensics.
{"title":"Choosing a password breaking strategy with imposed time restrictions","authors":"Przemysław Rodwald","doi":"10.5604/01.3001.0013.1467","DOIUrl":"https://doi.org/10.5604/01.3001.0013.1467","url":null,"abstract":"The aim of the article is to present the password breaking methodology in case when an attacker (forensic investigator, court expert, pen tester) has imposed time restrictions. This is a typical situation during many legal investigations where computers are seized by legal authorities but they are protected by passwords. At the beginning, the current state of law in that matter is presented, along with good practices in seizing the evidence. Then, the ways of storing static passwords in information systems are showed, after which various classes of password breaking methods are reviewed (dictionary, brute-force, rule, combinator, mask, hybrid, etc.). The most popular tools supporting this process are listed as well. The main part of the paper presents the original strategy of conducting an attack on a single hashed password with time constraints. Costs as well as economic efficiency for four different hardware solutions (laptop, gaming computer, rig with 6 GPU’s, cloud computing) are discussed. The calculations are shown on the example of two real attacks carried out by the author in the real legal cases.\u0000Keywords: passwords, breaking passwords, hash functions, computer forensics.\u0000\u0000","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71279121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-03-29DOI: 10.5604/01.3001.0013.1478
M. Suproniuk, J. Paś
In Poland, approx. 95% of electrical energy is generated in a coal combustion process. Saving electrical energy gives economic effects related to the smaller fees and contributes to protection of the natural environment. Additionally, saving electrical energy should translate into our health, lesser degradation of the natural environment, or less consumption of natural deposits of energy. The paper has presented the issues related to analysis of energy consumption in a selected building object. The analyse includes the following issues − document analysis related to the building’s power, energy distribution, and power consumption of individual load and time regimes of work of receivers in the object and analysis of electrical energy which has been measured in a building. Keywords: electricity quality parameters measurement, higher harmonics of current/voltage.
{"title":"Analysis of electrical energy consumption on the example of a selected building","authors":"M. Suproniuk, J. Paś","doi":"10.5604/01.3001.0013.1478","DOIUrl":"https://doi.org/10.5604/01.3001.0013.1478","url":null,"abstract":"In Poland, approx. 95% of electrical energy is generated in a coal combustion process. Saving electrical energy gives economic effects related to the smaller fees and contributes to protection of the natural environment. Additionally, saving electrical energy should translate into our health, lesser degradation of the natural environment, or less consumption of natural deposits of energy. The paper has presented the issues related to analysis of energy consumption in a selected building object. The analyse includes the following issues − document analysis related to the building’s power, energy distribution, and power consumption of individual load and time regimes of work of receivers in the object and analysis of electrical energy which has been measured in a building.\u0000Keywords: electricity quality parameters measurement, higher harmonics of current/voltage.\u0000\u0000","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71278766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-03DOI: 10.5604/01.3001.0011.8015
A. Górka
{"title":"Viscosity and surface tension in the biological microparticle filtration process","authors":"A. Górka","doi":"10.5604/01.3001.0011.8015","DOIUrl":"https://doi.org/10.5604/01.3001.0011.8015","url":null,"abstract":"","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"67 1","pages":"15-31"},"PeriodicalIF":0.0,"publicationDate":"2018-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45493626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-03DOI: 10.5604/01.3001.0011.8051
Aneta Brzuzy, G. Bąk
This paper presents the results of a numerical analysis of the elastic-plastic behaviour of steel compression members subjected to compression with a permanent pre-deformation in the longitudinal axis by a longitudinal indispensable shock load. A differential load intensity was considered up to the loss of stability. A finite difference method was applied, with an explicit integration schema for the time of the dynamic stability equations. It was assumed that the precursor to the unstable behaviour of a steel compression member was a continuous deformation of the rod axis, which was defined according to current industry-standard design procedures. Cases of flexible and stiff rods, varying in slenderness, were considered. It was demonstrated that a significant load on the performance of the steel compression members and their buckling mechanisms is attributable to longitudinal wave effects. These longitudinal wave effects cause high-frequency changes in the axial forces with a significant stress concentration due to the effect of reflection from a pinned support. This is critical for the dissipation of internal energy by plastic deformation. The applied research method facilitated an estimation of the dynamic critical forces and their relationships with static values.
{"title":"Stability analysis of steel compression members under shock loads","authors":"Aneta Brzuzy, G. Bąk","doi":"10.5604/01.3001.0011.8051","DOIUrl":"https://doi.org/10.5604/01.3001.0011.8051","url":null,"abstract":"This paper presents the results of a numerical analysis of the elastic-plastic behaviour of steel compression members subjected to compression with a permanent pre-deformation in the longitudinal axis by a longitudinal indispensable shock load. A differential load intensity was considered up to the loss of stability. A finite difference method was applied, with an explicit integration schema for the time of the dynamic stability equations. It was assumed that the precursor to the unstable behaviour of a steel compression member was a continuous deformation of the rod axis, which was defined according to current industry-standard design procedures. Cases of flexible and stiff rods, varying in slenderness, were considered. It was demonstrated that a significant load on the performance of the steel compression members and their buckling mechanisms is attributable to longitudinal wave effects. These longitudinal wave effects cause high-frequency changes in the axial forces with a significant stress concentration due to the effect of reflection from a pinned support. This is critical for the dissipation of internal energy by plastic deformation. The applied research method facilitated an estimation of the dynamic critical forces and their relationships with static values.","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"67 1","pages":"107-125"},"PeriodicalIF":0.0,"publicationDate":"2018-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48540190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-03DOI: 10.5604/01.3001.0011.8058
P. Grobelny, W. Dornowski
. The paper presents a method for determining the creep function of wood. A key feature of this method is a constitutive relation which includes the continuous effect of wood moisture on creep. The method can be applied to improve the precision of design of wooden structures as well to assess the safety of biodegraded (biologically corroded) structural elements fabricated from wood.
{"title":"Theoretical predictions on the influence of moisture on movements of wooden construction elements","authors":"P. Grobelny, W. Dornowski","doi":"10.5604/01.3001.0011.8058","DOIUrl":"https://doi.org/10.5604/01.3001.0011.8058","url":null,"abstract":". The paper presents a method for determining the creep function of wood. A key feature of this method is a constitutive relation which includes the continuous effect of wood moisture on creep. The method can be applied to improve the precision of design of wooden structures as well to assess the safety of biodegraded (biologically corroded) structural elements fabricated from wood.","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"11 2","pages":"175-184"},"PeriodicalIF":0.0,"publicationDate":"2018-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41270802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-03DOI: 10.5604/01.3001.0011.8035
G. Czopik, T. Kraszewski
{"title":"Low cost GNSS receivers in time synchronization systems","authors":"G. Czopik, T. Kraszewski","doi":"10.5604/01.3001.0011.8035","DOIUrl":"https://doi.org/10.5604/01.3001.0011.8035","url":null,"abstract":"","PeriodicalId":9068,"journal":{"name":"Biuletyn Wojskowej Akademii Technicznej","volume":"67 1","pages":"65-72"},"PeriodicalIF":0.0,"publicationDate":"2018-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47591088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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