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Analytical analysis of a circular unimorph piezoelectric actuator in the range of low voltages and pressures
No full textIn this study, the static displacement behaviour of a three-layer axisymmetric circular piezoelectric unimorph actuator subjected to voltage and uniform pressure loads for different mechanical and geometric properties of layers was investigated. The closed-analytical model of piezoelectric actuator based on the classical laminated thin plate theory was performed. Kirchhoff's thin plate theory for the mathematical model in closed form of the actuator was utilized. The superposition of transverse and lateral deflections expressions was used to obtain the displacement equation of the piezoelectric actuator. Then, the analytical model solutions were compared by finite element model solutions. It was observed that the results obtained from analytical model and finite element analysis were sufficiently compatible with each other. The effects of nondimensional physical and mechanical properties on the static deflection performance of the piezoelectric actuator were discussed using the analytical model. According to the results obtained, the physical and mechanical properties of the actuator had significant effects on the actuator displacement. Therefore, the results obtained in this study can be used to optimize the performance of the circular piezoelectric actuator
A Research on Local Administrators' Thoughts about Region Tourism: Artvin - Arhavi Example
No full textThe aim of the study is to determine the thoughts of local administrators, who are active in Arhavi destination, about tourism in the region and to determine their contribution to tourism industry. The data obtained by using the semi-structured interview technique within the scope of qualitative research method and the local managers of Arhavi district of Artvin province with unique natural, cultural, historical and touristic values of East Blacksea Region were evaluated through content analysis. According to the results of the research, it is determined that local administrators and institutions serving in Arhavi district have positive attitudes to tourism activities and participation in existing tourism activities. On the other hand, lack of coordination in activities related to tourism industry of relevant managers and institutions has been determined and efforts have been made to propose solutions to the problems related to the existing deficiencies and district tourism. In addition, local stakeholders, tourism enterprises and researchers have been offered research proposals for destinations
Maximal normal subgroups of the automorphism groups of free nilpotent groups
No full text#nofulltext#We prove that the subgroup of all IA-automorphisms of the automorphism group Aut(N) of a free nilpotent group N of infinite rank is normality-small. As a consequence, every maximal normal subgroup of the group Aut(N) is a lifting of a maximal normal subgroup of the automorphism group Aut(A) of the abelianization A = N/[N, N] of N
Measurement of the Born cross sections for e(+)e(-) -> D-s(+) D-s1 (2460)(-) +c.c. and e(+) e(-) -> D-s*(+) D-s1 (2460)(-)( )+ c.c.
No full textThe processes e(+)e(-) -> D-s(+) D-s1 (2460)(-) + c.c. and e(+) e(-) -> D-s*(+) D-s1 (2460)(-)+ c.c. are studied for the first time using data samples collected with the BESIII detector at the BEPCII collider. The Born cross sections of e(+)e(-) -> D-s(+) D-s1 (2460)(-) + c.c. at nine center-of-mass energies between 4.467 GeV and 4.600 GeV and those of e(+) e(-) -> D-s*(+) D-s1 (2460)(-)+ c.c. at root s = 4.590 GeV and 4.600 GeV are measured. No obvious charmonium or charmoniumlike structure is seen in the measured cross sections
Theoretical analysis of a cascade refrigeration system with natural and synthetic working fluid pairs for ultra low temperature applications
No full textIn this study, a theoretical model is established using Engineering Equation Solver (EES) software in order to investigate the effects of different design and operation parameters on the performance of the cascade systems for Ultra Low Temperature (ULT) between -50 degrees C and -100 degrees C. The analysis is performed for natural and synthetic refrigerant pairs to find an environmentally friendly alternative to commercial synthetic refrigerants. Effects of common parameters such as the evaporation temperature of low temperature cycle (LTC), the condensation temperature of high temperature cycle (HTC) and the temperature difference in the cascade heat exchanger (HX) have been investigated with the proposed model. Furthermore, influence of operation parameters including vapor quality of the refrigerant after the expansion valve and the precooler heat exchanger (PCHX) capacity, crucial to reach ULT conditions, on the system performance are examined. This study also contributes to the theoretical evaluation of the feasible natural refrigerant alternatives for ULT applications and the comparison of these refrigerants with synthetic ones in terms of performance and the environmental aspects. It is found that the natural refrigerant R1270/R170 pair results in about 5% better COP and almost half less CO2 emissions compared to synthetic refrigerant R404A/R508B pair
Spectrum Measurement of Variable Irradiance Controlled LED-Based Solar Simulator
No full textEfficiency of photovoltaic devices are based on testing all equipment and systems used to produce devices in a healthy way, from electrical and optical points of view. Considering that photovoltaic devices which enable the generation of electric energy from solar energy as a renewable energy source are widely used solar simulators should be utilized to provide actual daylight spectrum distributions. The most considerable component of solar simulators in photovoltaic device research is the light sources they use. Due to their advantages over conventional light sources, such as compactness, low power consumption, and low cost, research and studies on solar simulators use LEDs took place as their illumination source. In this study, it is aimed to produce a low-cost Class A solar simulator with using six different type power LEDs, as specified in the IEC 60904-9 and ASTM E927-05 standards. At the end of the study with 24 power LEDs with six different wavelengths, the spectral match which is one of the three performance criteria of the solar simulator was obtained as Class A. This study shows that LED-based solar simulators provide great savings in terms of energy consumption as well as a huge advantage in cost, compared to the widely used xenon arc lamp solar simulators
On the determination of transportation, range and distribution characteristics of Uranium-238, Thorium-232 and Potassium-40: a critical review
No full textThis research presents the theoretical and experimental results in real time and suggests spatial models after reviewing the spatial modelling method, which has an important place in earth sciences. It also reveals the geological and geophysical descriptions of mathematical models, calculations and the ease with which one can interpret the results. U-238, Th-232 and K-40 concentrations are determined in water and bottom sediment samples taken from Keban Lake as a sample study area. The point cumulative semi-variogram (PCSV) method application helps to identify the range, distribution and transport of radionuclide at each sampling station. The well-known semi-variogram (SV) is used in many scientific studies. In this study, the SV methodologies are reviewed leading to the application of the PCSV method for the real-time data. The radionuclide distributions in the lake are revealed by means of ten regional models. In addition, iso-radioactivity maps are obtained to provide an overview of the medium radioactivity with characterizations of the transport, range and distribution of the three radionuclides in the lake. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature
Post-Traumatic Stress Disorder Symptoms and Their Predictors in Earthquake or Fire Survivors
No full textAbstract
Objective: In this study, we aimed to investigate the relationship between post-traumatic stress disorder and previous knowledge of emergency management, sense of control over the stressor, perceived threat, and somatic symptoms in earthquake and fire survivors.. Method: The data were obtained from the 2009-database of the Izmir Province Fire Department to include the people who had experienced domestic fire (n=92), from the people who had applied to the Health Group Directory after the 2005 earthquake in Seferihisar (n=38) and from the staff of a third step hospital who experienced a fire in public building in 2010 (n=34). The Impact of Events Scale-revised version (IES-R) was used to determine the traumatic stress levels of the participants; and the Behavior, Security, and Culture - Survivor (BeSeCu- S) questionnaire was used to acquire information on factors before and after the traumatic events. Results: Compared to the fire survivors, the earthquake survivors perceived higher levels of threat and lower levels of control during the event gender, perceived threat, somatic symptoms experienced during the event and perceived control over the event were found to predict the post-traumatic stress disorder. Conclusion: Results of the research suggested that control-focused treatment methods could be effective in treatment of people who had experienced earthquake and fire. It is observed that informing the public about emergency management would be protective for mental health by increasing the sense of control of the individuals at the time of the incident. On the other hand, the positive relationship between PTSD and previous knowledge on emergency suggests that the ringing alarms and practice errors during the fire and earthquake drills could traumatize people. Future research is recommended on the relationship between information processing, somatic symptoms and emotional processes in individuals during earthquake, fire and their drills. © 2018, Turkish Association of Nervous and Mental Health
Designing a dynamic protocol for real-time Industrial Internet of Things-based applications by efficient management of system resources
No full textWireless sensor networks have gained the attention of researchers from various fields due to increased applicability. This has thus led to rapid development in the field. However, these networks still suffer from various challenges and limitations. These range from computation and processing power and available energy to mention but a few. These problems are even much more pronounced in some areas of the field such as real-time Internet of Things-based applications. In this study, a dynamic protocol that efficiently utilizes the available resources is proposed. The protocol employs five developed algorithms that aid the data transmission, neighbor, and optimal path finding processes. The protocol can be utilized in, but not limited to, real-time large-data streaming applications. The protocol is implemented on sensor nodes that are custom made by our research team. In this article, a structure that enables the sensor devices to communicate with each other over their local network or Internet as required in order to preserve the available resources is defined. Both theoretical and experimental result analyses of the entire protocol in general and individual algorithms are also performed. © The Author(s) 2019
Measurement of branching fractions for D meson decaying into ϕ meson and a pseudoscalar meson
No full textThe four decay modes D0→ϕπ0, D0→ϕη, D+→ϕπ+, and D+→ϕK+ are studied by using a data sample taken at the centre-of-mass energy s=3.773 GeV with the BESIII detector, corresponding to an integrated luminosity of 2.93 fb−1. The branching fractions of the first three decay modes are measured to be B(D0→ϕπ0)=(1.168±0.028±0.028)×10−3, B(D0→ϕη)=(1.81±0.46±0.06)×10−4, and B(D+→ϕπ+)=(5.70±0.05±0.13)×10−3, respectively, where the first uncertainties are statistical and the second are systematic. In addition, the upper limit of the branching fraction for D+→ϕK+ is given to be 2.1×10−5 at the 90% confidence level. The ratio of B(D0→ϕπ0) to B(D+→ϕπ+) is calculated to be (20.49±0.50±0.45)%, which is consistent with the theoretical prediction based on isospin symmetry between these two decay modes. © 2019 The Author(s