scholarly journals A New Approach for Solving Rub-Impact Dynamic Characteristics of Shrouded Blades Based on Macroslip Friction Model

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Guofang Nan ◽  
Jianyang Lou ◽  
Chuanchong Song ◽  
Min Tang
Keyword(s):  
Contact Angle ◽  
Vibration Amplitude ◽  
Research Work ◽  
Friction Model ◽  
Rotating Machinery ◽  
Equivalent Stiffness ◽  
Normal Contact ◽  
New Approach ◽  
Damping Characteristics ◽  
The Impact

Based on the macroslip friction model, a new dynamic model of the shrouded blades for rotating machinery is developed to study the impact vibration between the adjacent blades. Unlike the traditional analytical method of the shrouded blade based on the simple Coulomb friction model, a new approach is developed that the macroslip friction model is used to represent a more accurate rubbing behavior (more closer to reality) between the shrouds. By means of the harmonic balance method, the friction force and the normal pressure are translated into the equivalent stiffness and the equivalent damping. The Galerkin method is adopted to reduce the dimension of the equation to obtain the 1-DOF equation of motion, and the dynamic response of the shrouded blade is solved by Runge–Kutta numerical method. The effects of parameters such as the gap of shrouds, the mass of the tip, the contact angle, and the normal stiffness between the shrouded blades on the damping characteristics are discussed. The results show that the gap of tips has a significant effect on the vibration amplitude of the blade. Within a certain range, with the decrease of the gap, the amplitude of the blade tip is getting smaller while the resonant speed is increasing. The mass of the shroud has little effect on the damping characteristics, while the contact angle has a great influence on the equivalent stiffness and damping. Increasing the contact angle to a certain extent can effectively reduce the vibration amplitude of the blade, and the normal contact stiffness also has an important influence in reducing the vibration. The research results based on the new method in this paper are compared with the published articles and agree well. The research work is important to the accurate calculations and design and control of the shrouded blades for rotating machinery.

scholarly journals Improvement of Daylight Factor Model for Window Size Optimization and Energy Efficient Building Envelope Designs

2021 ◽  
Vol 8 (2) ◽  
pp. 204-221
Author(s):  
Chahrazed Mebarki ◽  
◽  
Essaid Djakab ◽  
Abderrahmane Mejedoub Mokhtari ◽  
Youssef Amrane ◽  
...  
Keyword(s):  
Energy Demand ◽  
Research Work ◽  
Optimal Solution ◽  
Window Size ◽  
Building Envelope ◽  
Nsga Ii ◽  
New Approach ◽  
Building Model ◽  
Heating And Cooling ◽  
The Impact

Based on a new approach for the prediction of the Daylight Factor (DF), using existing empirical models, this research work presents an optimization of window size and daylight provided by the glazed apertures component for a building located in a hot and dry climate. The new approach aims to improve the DF model, considering new parameters for daylight prediction such as the orientation, sky conditions, daytime, and the geographic location of the building to fill in all the missing points that the standard DF, defined for an overcast sky, presents. The enhanced DF model is considered for the optimization of window size based on Non dominated Sorting Genetic Algorithm (NSGA II), for heating and cooling season, taking into account the impact of glazing type, space reflectance and artificial lighting installation. Results of heating and cooling demand are compared to a recommended building model for hot and dry climate with 10% Window to Wall Ratio (WWR) for single glazing. The optimal building model is then validated using a dynamic convective heat transfer simulation. As a result, a reduction of 48% in energy demand and 21.5% in CO2 emissions can be achieved. The present approach provides architects and engineers with a more accurate daylight prediction model considering the effect of several parameters simultaneously. The new proposed approach, via the improved DF model, gives an optimal solution for window design to minimize building energy demand while improving the indoor comfort parameters.

scholarly journals Dynamic Performance of Partially Orifice Porous Aerostatic Thrust Bearing

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 989
Author(s):  
Muhammad Punhal Sahto ◽  
Wei Wang ◽  
Ali Nawaz Sanjrani ◽  
Cheng Xu Xu Hao ◽  
Sadiq Ali Shah
Keyword(s):  
Thrust Bearing ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Research Work ◽  
Analysis Model ◽  
Thrust Bearings ◽  
Damping Characteristics ◽  
Fluent Software ◽  
Perturbation Frequency ◽  
The Impact

The aerostatic thrust bearing’s performance under vibration brings certain changes in stiffness and stability, especially in the range of 100 to 10,000 Hz, and it is accompanied by significant increase in fluctuations due to the changes in frequency, and the size of the gas film damping. In this research work, an analysis is carried out to evaluate the impact of throttling characteristics of small size orifice on stiffness and stability optimization of aerostatic thrust bearings. There are two types of thrust bearing orifices such as: partial porous multiple orifice and porous thrust bearings and their effects on variations in damping and dynamic stiffness are evaluated. A simulation based analysis is carried out with the help of the perturbation analysis model of an aerostatic thrust bearing simulation by using FLUENT software (CFD). Therefore, two models of aerostatic thrust bearings—one with the porous and other with partial porous orifice are developed—are simulated to evaluate the effects of perturbation frequencies on the damping and dynamic stiffness. The results reveal a decrease in the amplitude of dynamics capacity with an increase in its frequency, as well as a decrease in the damping of partial porous aerostatic thrust bearings with an increase in the number of orifices. It also reveals an increase in the radius of an orifice with an increment of damping of bearing at the same perturbation frequency and, with an increase in orifice height, a corresponding decrease in the damping characteristics of bearings and in the dynamic stiffness and coefficient of damping of bearing film in the frequency range less than 100 Hz.

Measurements and Assessment of Sound Emitted by Toys Intended for Children under the Age of Three Years Old

2015 ◽  
Vol 40 (3) ◽  
pp. 383-393
Author(s):  
Beata Grynkiewicz-Bylina ◽  
Bożena Rakwic
Keyword(s):  
Intellectual Development ◽  
Research Work ◽  
Current Standard ◽  
New Approach ◽  
Adverse Health Effects ◽  
Level Measurement ◽  
Hearing Organ ◽  
Continuous Noise ◽  
The Impact ◽  
Children’S Exposure

AbstractToys emitting sounds are classified as significant sources of noise found in the children environment. Impulse and continuous noise emitted by toys, used in close to the child’s ear, acting directly on the organ of hearing, can lead to serious adverse health effects. This is especially true for children under the age of three, in which the state of the hearing organ determines their intellectual development.The current level of safety of sound emitting toys intended for children in this age group is insufficient. This is confirmed by the reports from the control of market surveillance authorities.A new approach to the assessment of children’s exposure to noise generated by toys, included in EN 71-1:2011 + A2:2013 Standard, based on the permissible values applicable to the workplaces, requires further tests and verification.The paper presents the results of the research work and assesses the level of sound emitted by toys in the light of current standard requirements, carried out using the author’s methodology. Toys intended for children under the age of 3 years, commercialized on the European market by Polish manufacturers and importers were tested. The results of the tests allowed us to determine the impact of duration of the sound pressure level measurement on the final result.

Piezoelectric β-polymorph formation of new textiles by surface modification with coating process based on interfacial interaction on the conformational variation of poly (vinylidene fluoride) (PVDF) chains

2020 ◽  
Vol 91 (3) ◽  
pp. 31301
Author(s):  
Nabil Chakhchaoui ◽  
Rida Farhan ◽  
Meriem Boutaldat ◽  
Marwane Rouway ◽  
Adil Eddiai ◽  
...  
Keyword(s):  
High Efficiency ◽  
Vinylidene Fluoride ◽  
Research Work ◽  
Research Area ◽  
Interfacial Interaction ◽  
Tetraethyl Orthosilicate ◽  
Poly Vinylidene Fluoride ◽  
Carbon Nanofillers ◽  
The Impact ◽  
Advanced Applications

Novel textiles have received a lot of attention from researchers in the last decade due to some of their unique features. The introduction of intelligent materials into textile structures offers an opportunity to develop multifunctional textiles, such as sensing, reacting, conducting electricity and performing energy conversion operations. In this research work nanocomposite-based highly piezoelectric and electroactive β-phase new textile has been developed using the pad-dry-cure method. The deposition of poly (vinylidene fluoride) (PVDF) − carbon nanofillers (CNF) − tetraethyl orthosilicate (TEOS), Si(OCH2CH3)4 was acquired on a treated textile substrate using coating technique followed by evaporation to transform the passive (non-functional) textile into a dynamic textile with an enhanced piezoelectric β-phase. The aim of the study is the investigation of the impact the coating of textile via piezoelectric nanocomposites based PVDF-CNF (by optimizing piezoelectric crystalline phase). The chemical composition of CT/PVDF-CNC-TEOS textile was detected by qualitative elemental analysis (SEM/EDX). The added of 0.5% of CNF during the process provides material textiles with a piezoelectric β-phase of up to 50% has been measured by FTIR experiments. These results indicated that CNF has high efficiency in transforming the phase α introduced in the unloaded PVDF, to the β-phase in the case of nanocomposites. Consequently, this fabricated new textile exhibits glorious piezoelectric β-phase even with relatively low coating content of PVDF-CNF-TEOS. The study demonstrates that the pad-dry-cure method can potentially be used for the development of piezoelectric nanocomposite-coated wearable new textiles for sensors and energy harvesting applications. We believe that our study may inspire the research area for future advanced applications.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

A NEW APPROACH TO INVESTIGATE CONTACT ANGLE HYSTERESIS

2018 ◽  
Author(s):  
Qiao Liu ◽  
Abbasali Abouei Mehrizi ◽  
Hao Wang
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
New Approach

Serving the People in Long Beach, California: Advancing Justice for Southeast Asian Youth through Community University Research Partnerships

2019 ◽  
Vol 16 (1-2) ◽  
pp. 1-34
Author(s):  
R. Varisa Patraporn
Keyword(s):  
Asian American ◽  
Research Work ◽  
Community Based Participatory Research ◽  
Youth Empowerment ◽  
Long Beach ◽  
Structured Interviews ◽  
Research Partnerships ◽  
Community Needs ◽  
The People ◽  
The Impact

Khmer Girl’s in Action is a nonprofit that successfully utilizes community-based participatory research (CBPR) with university partners to create social change for youth in Long Beach, CA. Based on semi-structured interviews and content analysis of news articles, I explore the impact and sustainability of this research work and the research partnerships. Findings highlight impacts such as youth empowerment, heightened awareness around community needs, policy change, and CBPR curriculum improvements in the field as impacts. Sustainability requires integrating research into program funding, utilizing a tailored training curriculum, building on community members prior relationships, and selecting partners that share common goals, levels of commitment, and flexibility. As funders demand more data to justify community needs, understanding more examples of such work in the Asian American community will be useful for informing future partnerships.

Impacto de las tecnologías de la información y las comunicaciones: Una mirada en la Educación Superior

2017 ◽  
Vol 1 (6) ◽  
Author(s):  
Karina Virginia Mero Suárez ◽  
Edwin Joao Merchán Carreño ◽  
Ana Del Rocío Fernández Torres ◽  
Narcisa María Crespo Torres
Keyword(s):  
Higher Education ◽  
Information Technology ◽  
Research Work ◽  
Field Research ◽  
Research Problem ◽  
Research Report ◽  
Educación Superior ◽  
Educational Design ◽  
Educacion Superior ◽  
The Impact

El artículo aborda la necesidad de la creatividad que se impone en la era actual del conocimiento y la importancia que  constituyen las tecnologías como herramientas indispensables en todas las esferas de la vida. En Trabajo toma como campo investigativo los cambios que se llevan a cabo en esta esfera en la Universidad Estatal del Sur de Manabí y la Universidad Técnica de Babahoyo, Ecuador, donde se toman como objeto el proceso de enseñanza aprendizaje en la Educación Superior. El objetivo de la investigación fue comunicar el impacto de las Tecnologías de la Información y las Comunicaciones en las Universidades, donde se hace énfasis en el nuevo rol de los docentes y su nuevo desempeño de facilitadores del aprendizaje en los educandos a través en los nuevos escenarios mediados por las tecnologías. Para el desarrollo exitoso de esta memoria investigativa se   usó como metodología instrumentos que se basaron fundamentalmente en documentos referativos que ayudaron a justificar el problema de investigación, el cual consistía fundamentalmente en el impacto de las nuevos  dispositivos tecnológicos y su utilidad en los centros de altos estudios del país. Se concluyó que las Tecnologías de la Información y Comunicación son herramientas indispensables en la docencia y al mismo tiempo la forma de intervenir en el diseño educativo que nos llevan a explorar nuevos métodos docentes en los escenarios educativos mediados por estas. Se constató además que estas herramientas favorecen satisfactoriamente al proceso si se tiene una buena preparación por parte del docente.   Palabras clave: Herramientas tecnológicas, universidades, formación, docencia universitaria, proceso de enseñanza – aprendizaje Impact of information technology and communications: a look at higher education  Abstract The article states the need of the creativity that prevails in the current era of knowledge and the importance that technologies constitute in all spheres of life. In field research work it takes as changes take place in this area in Southern State University of Manabí and the Technical University of Babahoyo, Ecuador, where they are taken as an object the process of learning in higher education. The aim of the research was to communicate the impact of Information Technology and Communications in the universities, where the emphasis is on the new role of teachers and their new performance of facilitators of learning in students through the new scenarios mediated by technologies. For the successful development of this research report it was used as a methodology instruments based mainly on referative documents that helped to justify the research problem, which consisted mainly of the impact of new technological devices and their use in the centers of higher learning in the country. It was concluded that information technology and communication are indispensable tools in teaching and at the same time how to intervene in the educational design that lead us to explore new teaching methods in educational settings mediated by these. It was further found that these tools successfully promote the process if there is a good preparation by the teacher.

An Energy Efficient Spectrum Aware Routing for Cognitive Radio Networks (CRNs)

2020 ◽  
Vol 10 ◽  
Author(s):  
Dileep Reddy Bolla ◽  
Jijesh J J ◽  
Mahaveer Penna ◽  
Shiva Shankar
Keyword(s):  
Cognitive Radio ◽  
Spectrum Sensing ◽  
Cognitive Radio Networks ◽  
Energy Efficient ◽  
Research Work ◽  
Spectrum Management ◽  
Residual Energy ◽  
Radio Networks ◽  
Traffic Load ◽  
The Impact

Back Ground/ Aims:: Now-a-days in the Wireless Communications some of the spectrum bands are underutilized or unutilized; the spectrum can be utilized properly by using the Cognitive Radio Techniques using the Spectrum Sensing mechanisms. Objectives:: The prime objective of the research work carried out is to achieve the energy efficiency and to use the spectrum effectively by using the spectrum management concept and achieve better throughput, end to end delay etc., Methods:: The detection of the spectrum hole plays a vital role in the routing of Cognitive Radio Networks (CRNs). While detecting the spectrum holes and the routing, sensing is impacted by the hidden node issues and exposed node issues. The impact of sensing is improved by incorporating the Cooperative Spectrum Sensing (CSS) techniques. Along with these issues the spectrum resources changes time to time in the routing. Results:: All the issues are addressed with An Energy Efficient Spectrum aware Routing (EESR) protocol which improves the timeslot and the routing schemes. The overall network life time is improved with the aid of residual energy concepts and the overall network performance is improved. Conclusion:: The proposed protocol (EESR) is an integrated system with spectrum management and the routing is successfully established to communication in the network and further traffic load is observed to be balanced in the protocol based on the residual energy in a node and further it improves the Network Lifetime of the Overall Network and the Individual CR user, along with this the performance of the proposed protocol outperforms the conventional state of art routing protocols.

Impact of Chatbot in Transforming the Face of Retailing- An Empirical Model of Antecedents and Outcomes

2019 ◽  
Vol 12 ◽  
Author(s):  
Kumari Anshu ◽  
Loveleen Gaur ◽  
Arun Solanki
Keyword(s):  
Research Work ◽  
Shopping Behavior ◽  
Model Framework ◽  
Shopping Experience ◽  
The Face ◽  
Strongly Agree ◽  
Different Characteristics ◽  
Work Done ◽  
The Impact ◽  
Self Administered Questionnaire

Chatbot has emerged as a significant resolution to the swiftly growing customer caredemands in recent times. Chatbot has emerged as one of the biggest technological disruption. Simply speaking, it is a software agent facilitating interaction between computers and humans in natural language. So basically, it is a simulated, intellectual dialogue agent functional in a range of consumer engagement circumstances. It is the easiest and simplest means enable interaction between the retailers and the customers. </p><p> • Purpose- Most of the research work done in this field is concerned with their technical aspects. The recent research on chatbot pay little attention to the impact it is creating on users’ experience. Through this work, author is making an effort to know the customer-oriented impact that the chatbot bear on the shoppers. The purpose of this study is to develop and empirically test a framework that identify the customer oriented attributes of chatbot and impact of these attributes on customers. </p><p> • Objectives- The study intends to bridge the gap between concepts and actual attributes and applications on the subject of Chatbot. The following research objectives can address the various aspects of Chatbot affecting the different characteristics of consumers shopping behaviors: a) Identify the various attributes of chatbot that bears an impression on consumer shopping behavior. b) Evaluate the impact of chatbot on consumer shopping behavior that leads to the development of chatbot usage and adoption among the customer. </p><p> • Design/Methodology/Approach – For the purpose of analysis, author has administered Factor analysis and Multiple regression using SPSS version 23 for identification of various attributes of Chatbot and knowing their impact on shoppers. A self-administered questionnaire from the review of literature is developed. Industry experts in the field of retailing and academician evaluate the questionnaire. Primary information from the respondents is gathered using this questionnaire. The questionnaire comprises of Likert scale on a scale of 1 to 5 where 1 stands for strongly disagree and 5 stands for strongly agree. Data is collected from 126 respondents, out of which 111 respondents were finally considered for study and analysis purpose. </p><p> • Findings – The empirical results show that the study identifies various attributes of chatbot like Trust, Usefulness, Satisfaction, Readiness to Use and Accessibility. It is also found that chatbot is really influencing the customers in providing them with shopping experience, which can be very helpful to the businesses for increasing the sales and creating repurchase intention among the customers. </p><p> • Originality/value – The recent research on chatbot pay little attention to the impact it is creating on customers who are actually interacting with it on regular basis. The research paper extends information for understanding and appreciating the customer oriented attributes of artificially intelligent Chatbot. In this regard, the author has developed a model framework and proposed the attributes identified. Through the work, author is also making an effort to test empirically the impact of the identified attributes on the shoppers.

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