Shear Induced Fiber Alignment and Acoustic Nanoparticle Micropatterning during Stereolithography

The stereolithograpy method, which consists of a light source to polymerize the liquid photocurable resin, can produce structures with complex shapes. Most of the produced structures are unreinforced neat pieces. The addition of reinforcement, such as fibers and particles are regularly utilized to improve mechanical properties and electrical conductivity of the printed parts. Added fibers might be chosen as short or continuous fibers and the properties of the reinforced composite materials can be significantly improved by aligning the fibers in preferred directions. The first aim of this dissertation is to enhance the tensile and flexural strengths of the 3d printed composites by using shear induced alignment of short fibers. The second aim is to print parts with conductive embedded microstructures by utilizing acoustic patterning of conductive particles. Both aims are utilized during the stereolithography process.A lateral oscillation mechanism, which is inspired by large amplitude oscillatory shear test, was designed to generate shear flow. The alignment method, which combines the lateral oscillation mechanism with 3d printed wall patterns, is developed to utilized shear flow to align the fibers in the patterned wall direction. Shear rate amplitude, fiber concentration, and patterned wall angle were considered as parameters during this study.The stereolithography device incorporated with oscillation mechanism was utilized to produce short fiber reinforced ceramic composites and short nanofiber reinforced polymer composites. Nickel coated short carbon fibers, alumina and silica short fibers were used to reinforce the ceramic matrix with different fiber contents. The printed walls were demonstrated to align the short fibers parallel to the wall which was different from the oscillation direction up to 45°. The flexural strength of the ceramic matrix was improved with the addition and alignment of the short fibers. The alumina nanofibers were used as reinforcement in the photocurable polymer resin. The alumina nanofibers were treated with a silane coupling agent to improve interfacial bond between alumina fibers and polymer resin matrix. The aligned specimen demonstrated improvement in tensile strength with increasing nanowire content and their alignment.A hexagon shaped acoustic tweezer was incorporated into the stereolithography device to pattern conductive micro- and nanoparticles. This new approach for particle microstructuring via acoustic aligning during the stereolithography was used to produce embedded conductive microstructures in 3d printed parts. The acoustic tweezer was used to pattern the conductive particles into horizontal, 60°, and 120° parallel striped lines. The influence of the particle percentage content onto the electrical resistivity and thickness of the patterned lines were also investigated for different materials such as copper, magnetite, and carbon fiber. The copper patterns show less resistance to electrical currents compare to magnetite and carbon nanofiber patterns. Additionally, the influence of the particle concentration to the height of the pattern was studied and the data was utilized to achieve conductivity along z-axis. Later, this approach was used to fabricate examples of embedded conductive complex 3D microstructures

The impact of psychological empowerment dimensions on job performance and mediating role of organizational commitment: An empirical study

Bu çalışmada iş performansına olumlu etkileri olduğu düşünülen psikolojik güçlendirme ve örgütsel bağlılık kavramları ele alınmıştır. TRB-2 Bölgesinde (Van, Hakkâri, Bitlis, Muş) kamuda eğitim sektöründe çalışanların katılımıyla (n=437) yapılan analizler neticesinde psikolojik güçlendirme boyutlarının (anlam, yetkinlik, etki, özerklik) iş performansını pozitif yönlü ve anlamlı olarak etkilediği tespit edilmiştir. Ayrıca örgütsel bağlılığın iş performansını pozitif yönlü ve anlamlı olarak etkilediği görülmüştür. Örgütsel bağlılığın, psikolojik güçlendirmenin alt boyutlarıyla iş performansı arasındaki ilişkide aracılık rolü oynadığı belirlenmiştir.In this study, the psychological empowerment and the organizational commitment concepts, known to be influential on job performance, are scrutinized. The data are collected from educational public employees (n=437) in TRB-2 region (Van, Hakkâri, Bitlis, Muş) of Turkey. It is found that the dimensions of psychological empowerment (meaning, competency, impact and autonomy) significantly and positively affect job performance and affective organizational commitment has a significant and positive impact on job performance while normative and continuance organizational commitment do not have. A significant and positive partial mediating role of organizational commitment on the association between psychological empowerment and job performance is revealed

Investigation of Attitudes of University Students towards Turkish Language Course and Distance Education

Turkish language course in Turkish higher education is compulsory for all programs. Being taught for two semesters, this course has started to be given in many universities through distance education in recent years. This new situation brings about the problem as to whether there is a relationship between attitude towards distance education and attitude towards Turkish language lesson. It was aimed in this study to examine and compare the attitudes of university students who take Turkish Language courses through distance education towards this course and distance education system in terms of various variables. In this descriptive research, a survey model was used to obtain data. The study group consists of the 181 freshmen attending a state university located in the south of Turkey and taking Turkish language lessons in the 2018-2019 academic year. Data were collected with attitude scales whose validity and reliability was tested. Difference tests between means were performed in data analysis. It was concluded in the study that the attitude of undergraduate freshman students towards Turkish Language course and distance education is above average, but not very high. It can also be foreseen according to findings of this study that university students' attitudes towards Turkish language course will improve as their attitudes towards distance education increase

PERCEIVED ORGANIZATIONAL SUPPORT, STRESS COPING BEHAVIORS AND MEDIATING ROLE OF PSYCHOLOGICAL CAPITAL: SPECIAL EDUCATION AND REHABILITATION CENTERS

High level stress in work place is known to be associated with negative organizational behaviors and bad organizational performance. There are individual and organizational factors influencing stress coping behavior of employees. In this study we explore the impact of employees’ perceptions of organizational support on their stress coping capabilities (problem-focused stress coping and emotion-focused stress coping) and whether their psychological capital (PsyCap) plays a mediating role in this relationship using the sample of employees in special education and rehabilitation centers in Turkey. Multivariate statistical analyses show a significant positive relationship between perceived organizational support (POS) and problem-focused stress coping (PFSC), and no significant relationship between POS and emotion-focused stress coping (EFSC). A significant positive association is detected between POS and PsyCap. Accordingly, our findings show that PsyCap plays a partial mediating role in the association between POS and PFSC.JEL Codes - D22; M12; L

Effects Of Different Irrigation Regimes On Water Use And Vegetative Growth Parameters Of Almond Trees

Farklı sulama suyu uygulamalarının badem ağaçlarının su kullanımı ve vegetatif gelişme parametrelerine etkilerinin araştırıldığı çalışma, 2014 ve 2015 yıllarında Tekirdağ koşullarında yürütülmüştür. Araştırmada, A sınıfı buharlaşma kabından ölçülen buharlaşma değerlerinin %50, 75 ve 100’ ünün uygulandığı üç farklı sulama suyu uygulaması gerçekleştirilmiştir. Araştırma sonucunda, deneme konularında ölçüm periyodu boyunca ölçülen bitki su tüketimi değerleri uygulanan sulama suyu miktarlarına bağlı olarak 2014 yılında 256.45 ile 299.72 mm, 2015 yılında ise 325.82 ile 396.76 mm arasında değişmiştir. Uygulanan sulama suyu miktarı arttıkça ölçülen bitki su tüketimi değerleri artmıştır. Araştırmada ayrıca farklı sulama suyu uygulamalarının badem ağaçlarının vegetatif gelişme parametrelerine olan etkisi de irdelenmiştir. Bu değerlere göre hazırlanan varyans analiz sonuçlarında, uygulanan sulama suyu miktarlarının badem ağaçlarının vegetatif gelişme parametrelerini istatistiksel olarak etkilemediği sonucuna varılmıştır.The experiment was conducted during the growing season of 2014 and 2015 to evaluatethe water use and vegetative growth parameters of almond trees under different irrigation water levels. The three different irrigation water levels applied based on the ratio of Class A pan evaporation as 50, 75 and 100% were created in the research. As a result of this study, the seasonal evapotranspiration in the treatments during the measurement period varied from 256.45 and 299.72 mm in 2014 and from 325.82 and 396.76 mm in 2015 depending on the irrigation water applied. The measured evapotranspiration increased with increasing amout of water. The effect of the vegetative growth parameters of almond trees was also examined under the different irrigation levels. According to statistical analyses, the different irrigation levels did not affect the almond trees vegetative growth parameters, statistically

Psikolojik Güçlendirme Boyutlarının İş Performansı Üzerine Etkisinde Örgütsel Bağlılığın Aracılık Rolü: Görgül Bir Araştırma

In this study, the psychological empowerment and the organizational commitment concepts, known to be influential on job performance, are scrutinized. The data are collected from educational public employees (n=437) in TRB-2 region (Van, Hakkâri, Bitlis, Muş) of Turkey. It is found that the dimensions of psychological empowerment (meaning, competency, impact and autonomy) significantly and positively affect job performance and affective organizational commitment has a significant and positive impact on job performance while normative and continuance organizational commitment do not have. A significant and positive partial mediating role of organizational commitment on the association between psychological empowerment and job performance is revealed.Bu çalışmada iş performansına olumlu etkileri olduğu düşünülen psikolojik güçlendirme ve örgütsel bağlılık kavramları ele alınmıştır. TRB-2 Bölgesinde (Van, Hakkâri, Bitlis, Muş) kamuda eğitim sektöründe çalışanların katılımıyla (n=437) yapılan analizler neticesinde psikolojik güçlendirme boyutlarının (anlam, yetkinlik, etki, özerklik) iş performansını pozitif yönlü ve anlamlı olarak etkilediği tespit edilmiştir. Ayrıca örgütsel bağlılığın iş performansını pozitif yönlü ve anlamlı olarak etkilediği görülmüştür. Örgütsel bağlılığın, psikolojik güçlendirmenin alt boyutlarıyla iş performansı arasındaki ilişkide aracılık rolü oynadığı belirlenmiştir

Which out-of-office measurement technique should be used for diagnosing hypertension in prehypertensives?

Hypertension (HT) is diagnosed with high office blood pressure (BP), although confirmation with the addition of out-of-office measurements is currently recommended. However, insufficient data are available concerning the use of out-of-office BP measurement techniques for the diagnosis of HT in the prehypertensive population. The aim of the present study was to determine which out-of-office measurements yielded earlier and more frequent detection of development of HT in prehypertensive patients. Two hundred seven prehypertensive patients under monitoring in the Cappadocia cohort were included in the study. Office BP was measured five times at 1-min intervals, followed by 24-h ambulatory BP monitoring (24-h ABPM). Home BP measurement (HBPM) was performed five times, at the same times in the morning and evening, at 1-min intervals for 1 week. The same procedure was carried out at 4-6-month intervals for ~2 years. HT was diagnosed in 25.6% of subjects, masked HT in 11.1%, and white coat HT in 2.9%, while 23.7% remained prehypertensive and 36.7% became normotensive. Briefly, 56.6% of the patients with HT were diagnosed with office plus 24-h ABPM, 13.2% with office plus HBPM, and 30.2% with office plus HBPM and 24-h ABPM. Office with 24-h ABPM yielded statistically significantly more diagnoses (p < 0.001). In conclusion, our prospective observational study evaluated the usefulness of out-of-office BP measurements in confirming diagnosis of HT in prehypertensive patients. The findings show that 24-h ABPM detected HT earlier and more frequently in this high-risk population

An overview of the existing and future state of the art advancement of hybrid energy systems based on PV-solar and wind

Increasing solar and wind power use in existing power systems could create significant technical issues, especially for grids with poor connectivity or stand-alone systems needing more adequate storage capacity. This is due to the unpredictable and intermittent nature of solar and wind power. The intermittent nature of solar and wind resources can be reduced by integrating them optimally, making the entire system more reliable and cost-effective to operate. The advantages and disadvantages of hybrid wind and solar energy integration systems are discussed in this research. The impact of voltage and frequency oscillations and harmonics is amplified in weak grids, affecting both grid-connected and stand-alone systems. This may be fixed by ensuring that hybrid systems are well designed, equipped with cutting-edge quick reaction control capabilities, and optimized. This review offers an overview of existing advances in PV-solar and wind-based hybrid energy systems while exploring potential future developments. Further, this review also provides an overview of the primary studies published on optimum design considerations for compactness, topologies for power electronics, and control. As the global energy environment shifts toward sustainability and resilience, this review helps researchers, policymakers, and industry stakeholders understand, adapt, and enhance PV-solar-wind hybrid energy systems

Power system resilience and strategies for a sustainable infrastructure: A review

The increasing occurrence of severe vulnerabilities, such as natural catastrophes and man-made attacks, has resulted in a corresponding rise in power outages on a global scale. Given the growing recognition of such exceptional occurrences, there is a pressing need to examine the matters pertaining to resilience and the mitigation of risks. This study presents a comprehensive overview of the current state-of-the-art in power system resiliency, as well as an exploration of the measures required to ensure a sustainable environment.These instances of measures include resilience by enabling localized generation and distribution of electricity,diversification of energy resources, withstanding of severe weather conditions, cyberattacks and enabling communities to proactively address the consequences of power outages. There are multiple approaches to bolstering resiliency, which aim to facilitate recovery from unforeseen circumstances and promote stability in the face of uncertain events. These measures also serve to mitigate the impact of unexpected incidents such as power outages. Integrating unpredictable renewable energy sources like solar and wind power into energy networks is difficult, especially in terms of resilience. Renewable energy output fluctuates owing to weather and time of day, requiring sophisticated grid management, energy storage, and demand-response mechanisms to maintain system balance and resilience. This study elucidates the enhanced principles of power system dependability and resilience, in addition to several ways for establishing a sustainable power ecosystem. It examines the complex dynamics of risk assessment, including equipment failures, natural disasters, and human errors, to determine their likelihood and implications. Moreover, the study thoroughly examines the critical moments that occur after accidents, emphasizing the need of prompt reaction and recovery measures in reducing downtime and restoring regular operations to impacted power networks. This involves determining the fundamental reasons behind the incidents, such as whether they arise from equipment malfunctions, human mistakes, external influences like natural calamities, or cyber assaults. In addition, the report examines the efficacy of current response protocols and emergency procedures in reducing the impact of accidents and restoring regular operations to impacted electrical systems

An overview of the existing and future state of the art advancement of hybrid energy systems based on PV-solar and wind

Increasing solar and wind power use in existing power systems could create significant technical issues, especially for grids with poor connectivity or stand-alone systems needing more adequate storage capacity. This is due to the unpredictable and intermittent nature of solar and wind power. The intermittent nature of solar and wind resources can be reduced by integrating them optimally, making the entire system more reliable and cost-effective to operate. The advantages and disadvantages of hybrid wind and solar energy integration systems are discussed in this research. The impact of voltage and frequency oscillations and harmonics is amplified in weak grids, affecting both grid-connected and stand-alone systems. This may be fixed by ensuring that hybrid systems are well designed, equipped with cutting-edge quick reaction control capabilities, and optimized. This review offers an overview of existing advances in PV-solar and wind-based hybrid energy systems while exploring potential future developments. Further, this review also provides an overview of the primary studies published on optimum design considerations for compactness, topologies for power electronics, and control. As the global energy environment shifts toward sustainability and resilience, this review helps researchers, policymakers, and industry stakeholders understand, adapt, and enhance PV-solar-wind hybrid energy systems