bluuebunny/crossref_metadata_2025 huggingface dataset:
Identifying Communities of Concern for Older Adults Using Spatial Analysis: Focusing on Accessibility to Health, Social, and Daily Services
Authors: Choi Kwangyul , Lee Yeonjung , Basrak Zoe
Published: January 2021

Ensuring accessibility to necessary services is critical for older adults. However, there often exist spatial disparities in the levels of accessibility to services. Because the application of Geographic Information System (GIS) has gained attention in the gerontology field, we used spatial analysis to identify communities of concern for older adults from the perspective of accessibility. We defined the communities of concern based on the proportion of older adults and the level of accessibility to health, social, and daily services via two specific modes of transportation—walking and public transit. Our findings show that newly developed communities tend to have less accessibility to necessary services, and aging communities are randomly distributed across the city. Our results call for interdisciplinary collaboration, between urban planning and gerontology professionals, to better understand the spatial pattern of aging communities and its implication for properly addressing the mobility needs of older adults in the communities.
Inhibitory Mechanism of Engeletin Against α-Glucosidase
Authors: Li Yunbo , Liu Xiaoling , Zhou Haoyu , Li Bo , Mazurenko Igor Kostiantinovich
Published: January 2021

The inhibitory mechanism of engeletin against α-glucosidase was investigated for the first time by fluorescence spectroscopy and molecular docking. The results showed that engeletin could inhibit α-glucosidase in a noncompetitive inhibition mode with a half-maximal inhibitory concentration value of 48.5 ± 6.0 µg/mL (0.11 ± 0.014 mmol/L). It was found that engeletin could cause static fluorescence quenching of α-glucosidase by forming a complex with α-glucosidase. The thermodynamic parameters indicated that the combination of engeletin and α-glucosidase was driven by hydrophobic force. The molecular docking results confirmed that some amino acid residues of α-glucosidase (Trp391, Arg428, Glu429, Gly566, Trp710, Glu771) could interact with engeletin by hydrogen bonding.
Chemical Activators of the Nrf2 Signaling Pathway in Nonalcoholic Fatty Liver Disease
Authors: He Yinghua , Jiang Jianping , He Beihui , Shi Zheng
Published: January 2021

Nonalcoholic fatty liver disease (NAFLD) is paralleling the insulin resistance and obesity epidemic and is regarded as liver metabolic syndrome, and its prevalence rate is increasing rapidly. The best explanation for the occurrence and development of NAFLD is the “multiple hit” hypothesis instead of the “two-hit” hypothesis. At present, NAFLD therapies are limited. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway is a key pathway in oxidative stress. Its downstream proteins/enzymes are regulated. Metabolic enzymes and antioxidant proteins/enzymes play a vital role in cell defense protection and have attracted attention in the field of antioxidant research in recent years. This paper summarizes the regulatory mechanism of the Nrf2 signaling pathway and the research progress of Nrf2 activators in NAFLD to provide guidance for NAFLD therapy in the future.
Are tyrosine kinase inhibitors fit for purpose in the treatment of metastatic papillary renal cell carcinoma?
Authors: Hemmant Joshua , Chow Karyee
Published: January 2021

Renal cell carcinoma encompasses a range of histological subtypes. The treatment of metastatic disease in this context remains challenging. Papillary renal cell carcinoma is the second most common subtype and forms a significant subsection of non-clear cell renal cell carcinoma. Tyrosine kinase inhibitors form a significant part of the treatment of this largely incurable disease; however, outcomes tend to be poor. The aim of this article is to scrutinise whether these treatments are evidence-based in their use for metastatic papillary renal cell carcinoma and if good outcomes are reported. A literature review was made using PubMed of major prospective and retrospective studies. The European Association of Urology and European Society of Medical Oncology have both published guidance suggesting sunitinib should be offered first line in the treatment of metastatic papillary renal cell carcinoma. This, however, is based upon weak evidence produced by the ASPEN trial, although this did not discriminate between non-clear cell subtypes and results in further studies were modest. The National Institute for Care and Health Excellence has recently published new guidelines for the use of cabozantinib, which has shown evidence of improved progression-free survival and overall response rates compared with sunitinib. Unfortunately, many of the relevant studies did not specifically assess these treatments in patients solely with papillary renal cell carcinoma and had modest overall success. There is weak evidence that tyrosine kinase inhibitors give significant benefit in those patients with metastatic papillary renal cell carcinoma.

Level of evidence: 2a
Synovial sarcoma of the hand-wrist: a case report and review of the literature
Authors: Serinelli Serenella , Gitto Lorenzo , Zaccarini Daniel J.
Published: January 2021

Background

Synovial sarcomas are infrequent malignant tumors occurring mostly in adolescents and young adults. The occurrence of synovial sarcoma in the hand-wrist area is rare (4 to 8.5% of all synovial sarcomas in different studies).

Case presentation

This report documents an uncommon case of synovial sarcoma occurring in the hand-wrist of a 69-year-old Caucasian woman. She was subsequently treated with surgical excision and radiotherapy without recurrence after follow up.

Conclusions

This paper aims to characterize the demographic, pathologic, and clinical features with a literature review. The present literature review confirms that hand-wrist synovial sarcomas are more frequent among males and subjects 10 to 40 years old. Most cases in this location are usually not larger than 5 cm in size. The five-year survival rate is higher than that reported in a previous review on hand synovial sarcomas, and this suggests an improved survival in recent decades.
Correction to: Wind turbine performance analysis for energy cost minimization
Authors: Charabi Yassine , Abdul-Wahab Sabah , Ziaiefar Hamidreza
Published: January 2021

An amendment to this paper has been published and can be accessed via the original article.
3D Printing as a Promising Tool in Personalized Medicine
Authors: Vaz Vanessa Marcia , Kumar Lalit
Published: January 2021

Personalized medicine has the potential to revolutionize the healthcare sector, its goal being to tailor medication to a particular individual by taking into consideration the physiology, drug response, and genetic profile of that individual. There are many technologies emerging to cause this paradigm shift from the conventional “one size fits all” to personalized medicine, the major one being three-dimensional (3D) printing. 3D printing involves the establishment of a three-dimensional object, in a layer upon layer manner using various computer software. 3D printing can be used to construct a wide variety of pharmaceutical dosage forms varying in shape, release profile, and drug combination. The major technological platforms of 3D printing researched on in the pharmaceutical sector include inkjet printing, binder jetting, fused filament fabrication, selective laser sintering, stereolithography, and pressure-assisted microsyringe. A possible future application of this technology could be in a clinical setting, where prescriptions could be dispensed based on individual needs. This manuscript points out the various 3D printing technologies and their applications in research for fabricating pharmaceutical products, along with their pros and cons. It also presents its potential in personalized medicine by individualizing the dose, release profiles, and incorporating multiple drugs in a polypill. An insight on how it tends to various populations is also provided. An approach of how it can be used in a clinical setting is also highlighted. Also, various challenges faced are pointed out, which must be overcome for the success of this technology in personalized medicine.
Low Carbon Tourism: an Explorative Study on Walking Tours Fostering Responsible Tourism in Delhi
Authors: Chandran Anu , Kashyap Simran , Golla Suneeth Bosipoina
Published: January 2021

Sustainable management of destinations strongly advocates for low carbon emission tourism ventures that are eco-friendly. Tourism, however, has a profound potential of sensitisation. Walking Tours are increasingly becoming important for responsible tourism. Delhi is amongst the highly polluted cities of the world though it possesses amazing facets of tourism. While unveiling the relationship between walking tours and responsible tourism, this explorative study underscores the perspectives of the enablers of walking tours in the capital city.
Study of Stakeholder’s Perception Regarding Destination Branding Strategies of Maharashtra State, India
Authors: Kamble Pallavi , Sawant Madhuri
Published: January 2021

The paper aims to study the perceptions of tourism stakeholders of Maharashtra regarding effectiveness of branding and marketing strategies. It is the state which is receiving maximum number of foreign tourists in India. For this study, a survey of 178 tourism stakeholders was conducted. A structured questionnaire was used for rating the branding strategies of the destination. Data was analysed with the help of important performance analysis method and paired sample t-test was applied. Results of the study showed that, though the Maharashtra Tourism is successful in projecting a simple, appealing, believable and distinct image with help of ‗Unlimited Maharashtra‘ brand, there is need of innovative advertising tactics for effective branding of the Maharashtra Tourism to attract more international tourists.
Motivation for Adventure Tourism through Off-Roading – A Study in the Hill Areas of Kerala, India
Authors: Joy Tony , Antony Jose K
Published: January 2021

Increase in the number of participants who are interested in Off-Roading Trips has contributed to the growth of the local tourism economy of the hill areas of Kerala, but it was found that Off-Roading without any control, would create serious repercussions to the natural environment in the areas. The study focused on the popularity and the significance of Off-Roading Trips in the Hill Areas of Kottayam, Idukki, Pathanamthitta and Wayanad and suggests strategies to be adopted so as to improve sustainable Off-Roading practices in the regions.
Chhath Puja - A Study in Religious and Cultural Tourism
Authors: Badikilaya Githa
Published: January 2021

Commentary
Tourist Satisfaction and Destination Loyalty: A Case study of the World Heritage Site of Ellora Caves
Authors: Gaikwad Sonali Tirath , Ragde Rajesh , Sawant Madhuri
Published: January 2021

The willingness of Tourists to revisit a destination is strongly influenced by tourist satisfaction which plays a vital role in improving destination loyalty. The present research aims to study destination loyalty of the tourists based on their satisfaction at the world heritage site of Ellora caves in India.The sampling group of the study consisted of 60 tourists who visited Ellora Caves in July 2019. Pearson correlation analysis was applied for data analysis. The study concluded that there was a positive and strong affiliation between tourist satisfaction and destination loyalty. Constructive suggestions like adherence of strict rules & regulations and quality training programmes for service providers were given to improve tourist’s delight at Ellora Caves. The suggestions given are applicable for destination planners, and tourism authorities for future revisits.
A Scrutiny on the Cognisance of Indian and Foreign Wine Tourists on the Furtherance of Oenology Tourism in Bangalore
Authors: Thaliath Avin , Singh D. Tejinder
Published: January 2021

Tourism is lively and dynamic. A continual search seems to happen over the new frontiers in technologies, and fresh destinations. This paper attempts to investigate Bangalore as a prospective destination for wine tourism, alongside benchmarking its evolution and management. Bangalore, given its resource rich status, is profoundly suitable to grow vines, most of which produce wine that meets international expectations and standards. The global benchmarking standards for wine tourism include dimensions such as infrastructure facilities for wine tourists, packages for the promotion of wine tourism, development plan related to wine tourism and goals for wine tourism Scale Testing of significant difference - independent sample test and ANOVA – constructs by demographics. The findings say that the perception of both Indian and foreign respondents regarding the rating of each dimension of the promotion of wine tourism does not differ from each other.
Navigating the Insight of Gender Disparity Issues in Tourism: A Conceptual Study
Authors: Mitra Ishita , Sankar M. Mallika
Published: January 2021

Tourism experience has been perceived traditionally in terms of products, destinations, and consumption patterns. However, modern travelling is seen as an experience, performance, surveillance, play, relationship, and a form of mobility. Research studies in tourism explored gender as a global phenomenon of biased consequence. This paper attempts to conceptualize the agreements relating to ‘tourism is a gender determined activity. Further, investigates the most crucial gender trends affecting tourist destination, like subjectivity and critically examines the premise that destination is actually a perceptual concept, interpreted by consumers and also a result of the moment, the people and motive of their travel.
Political Impacts of Tourism: A Critical Analysis of Literature
Authors: Pradeep Chaitanya
Published: January 2021

Tourism and politics are inexorably allied. There exists adequate literature on the nexus between political ideologies and public institutions yet, there is hardly any explicit attention paid to the field of tourism research. It may perhaps due to the impression that ‘politics is all about power.’ In fact, Gramscian’ s notion of ‘power-over’ in the context of preserving cultural hegemony confines the prospects of political discourse to ‘power-itself’. This notion was contested through a poststructuralist thought, ‘power-to’, proposed by Michel Foucault. Thus, the present paper extends the poststructuralist thought by exploring the potential areas in politics that shape the outlook of the tourism industry through a critical analysis of literature. The study argues that the associated political effects are critical to the field of tourism at the same time the tourism industry is also a potential means to promote and showcase the political ideology.
Clique polynomials of $2$-connected $K_{5}$-free chordal graphs
Authors: FAAL Hossein Teimoori
Published: January 2021

In this paper, we give a generalization of the author's previous result about real rootedness of clique polynomials of connected $K_{4}$-free chordal graphs to the class of $2$-connected $K_{5}$-free chordal graphs. The main idea is based on the graph-theoretical interpretation of the second derivative of clique polynomials. Finally, we conclude the paper with several interesting open questions and conjectures.
Geoid undulation prediction using Gaussian Processes Regression: A case study in a local region in Turkey
Authors: Konakoglu Berkant
Published: January 2021

In order to convert ellipsoidal heights obtained by the Global Navigation Satellite System (GNSS) to orthometric heights, it is necessary to know the distance between the ellipsoidal and geoid surface, called the geoid undulation. The geoid undulation can be predicted using emerging mathematics tools and algorithms. The objective of this study was to develop a model for predicting the geoid undulation using Gaussian process regression (GPR), one of the soft machine learning algorithms having different covariance functions. This method was then compared with the radial basis function neural network (RBFNN), generalized regression neural network (GRNN), and the interpolation method of inverse distance to a power (IDP) with the power of 1, 2, 3, 4, and 5. First, 70 % of GNSS/leveling data (422 points) were used in the training phase. The remaining 185 points were used as testing data to check the effectiveness of the constructed model. In the GPR modeling, ten covariance functions (Materniso d= 1, 3, 5; Maternard d= 1, 3, 5; SEiso; SEard; RQiso; and RQard) were tested for prediction on this dataset. The GPR based on the Materniso (d = 1) covariance function model was introduced as an effective method for predicting geoid undulation and provided the best results (RMSE = 8.32 cm, MAE = 5.51 cm, R2 = 0.98968) when compared with the other developed GPR models. In addition, the statistical findings showed that the accuracy of all the GPR models was also better in predicting geoid undulation than the RBFNN, GRNN, and IDP with the power of 1, 2, 3, 4, and 5.
RGB-color forward-viewing spectrally encoded endoscope using three orders of diffraction
Authors: Ikuta Mitsuhiro , Wu Tzu-Yu , Mach Anderson T. , Altshuler Alexander , Yan Xuri , Houskeeper James H. , Yamamoto Akira , Tatsumi Shumpei , Iwata Ken-ichi , Ryu Jiheun , Zeidan Adel , Tearney Guillermo J. , Takeuchi Seiji
Published: January 2021

Spectrally encoded endoscopy (SEE) is an ultra-miniature endoscopy technology that encodes each spatial location on the sample with a different wavelength. One challenge in SEE is achieving color imaging with a small probe. We present a novel SEE probe that is capable of conducting real-time RGB imaging using three diffraction orders (6th order diffraction of the blue spectrum, 5th of green, and 4th of red). The probe was comprised of rotating 0.5 mm-diameter illumination optics inside a static, 1.2 mm-diameter flexible sheath with a rigid distal length of 5 mm containing detection fibers. A color chart, resolution target, and swine tissue were imaged. The device achieved 44k/59k/23k effective pixels per R/G/B channels over a 58° angular field and differentiated a wide gamut of colors.
Markov chains for modeling complex luminescence, absorption, and scattering in nanophotonic systems
Authors: Kutayiah A. Ryan , Kumar Smriti , Ratnaweera Rivi , Easwaran Kenny , Sheldon Matthew
Published: January 2021

We developed a method to model fluorescence, absorption, and scattering in nanophotonic systems using ergodic Markov chains. Past works have used absorbing Markov chains to find the long-run angle-dependent distribution of emitted photons. In contrast, we use ergodic Markov chains to focus on the steady state distribution of photons within various media, giving additional insight into the macroscopic optical response during illumination. We show that the method reproduces Beer-Lambert’s Law and Kirchhoff’s Law, and can quantify deviations from these laws when their assumptions are violated. We also use the method to model luminescent solar concentrators (LSCs) based on semiconductor nanocrystals.
Gerardo CAETANO y Fernando MAYORGA (comps.). Giros políticos y desafíos democráticos en América Latina: enfoques de casos nacionales y perspectivas de análisis. Buenos Aires: CLACSO, 2020. 245 pp. ISBN: 978-987-722-579-2.
Authors: Silva Marcos Antonio da
Published: January 2021

És una reseña de la obra: Caetano, Gerardo y Mayorga, Fernando (comp.). Giros políticos y desafíos democráticos en América Latina: enfoques de casos nacionales y perspectivas de análisis. Buenos Aires: CLACSO, 2020.
Kihívások és lehetőségek a hazai megújuló energiaszektorban (Challenges and possibilities in the Hungarian renewable sector)
Authors: Fodor Bea
Published: January 2021

A megújuló energiatermelés szerepének erősödését figyelhetjük meg az utóbbi években, évtizedekben. A zöldenergiák iránti igényt három fő motivátorcsoporttal lehet indokolni: ellátásbiztonság növelése, környezetvédelem és gazdaságélénkítés. Ezek a szempontok együttesen a fenntartható fejlődést szolgálják, és egyre inkább előtérbe kerülnek mind az EU, mind pedig hazánk szintjén. Magyarország 2010 végén az EU által előírt, 2020-ra elérendő 13%-os megújuló energiaarányt meghaladó, 14,65%-os vállalást tett a Nemzeti Cselekvési Tervben, ezzel is kifejezve elköteleződését a zöldenergiák ösztönzése felé. A jelenlegi kapacitások több mint megkétszerezését igénylő cél a hazai megújuló energiaszektor számára érdemi lehetőségeket jelent, de ezek megvalósításához szükség lenne az ígért új zöldenergia-támogatási rendszer, mielőbbi életbe lépésére. ____ The role of the renewable energy generation is getting even bigger and bigger in the last years, decades. The demand for the green energy has three main motivators: energy security, protecting the environment and fostering innovation. These goals serve the conception of sustainable development, and their function is increasingly highlighted in the EU and in Hungary as well. The EU has prescribed Hungary to reach a 13% share of renewable energy sources in 2020, but in the Hungarian national renewable action plan we have aimed to top the EU request, and to reach a 14,65% in the renewable proportion. This shows that our country is committed to inspire the renewables. In order to reach this goal, Hungary has to more than double its green power plant capacity, which means great possibilities in the sector; but at the same time means challenges as well, because the new renewable promoting system needs to come into force as soon as possible.
Un proceso de innovación colaborativa institucional a través de la práctica reflexiva: el caso del proyecto “Innovate” de Apdes
Authors: Montserrat María Inés , Caldarola César , Llera Martina
Published: January 2021

Experiencia documentada desarrollada en 21 centros educativos de Argentina pertenecientes a la red Apdes a partir de un proceso de innovación colaborativa institucional. Al asignar a los directores un rol de liderazgo de la práctica reflexiva de los equipos docentes, fueron empoderados como agentes de cambio y observadores del proceso completo, en tanto evaluación y redireccionamiento. A lo largo de este proceso, se aplicaron encuestas e instrumentos cualitativos orientados a recabar información sobre el concepto de innovación de los docentes y su nivel de motivación. Asimismo, fue posible evaluar cada uno de los pasos del proceso y percibir el nivel de compromiso, los obstáculos y los cambios en la valoración del proyecto. A partir del análisis de la información existente se percibe el impacto de la práctica reflexiva como un modelo facilitador de la coinnovación educativa.
Going left or right? A study of the policy rationale of the Chilean center-left coalition Concertación in Education
Authors: Falabella Alejandra
Published: January 2021

What does it mean to deliver left-wing policies in education nowadays? During most of the 20th century, political parties of the center-left traditionally fought for a welfare state and a comprehensive public education. However, in an era of advanced capitalism, these same parties have tended to advocate and even deepen neoliberal and new public management reforms. In Chile, the center-left “Concertación” coalition governed for 20 years (1990-2010), inheriting a market-driven educational system established under the dictatorship of Augusto Pinochet. This paper, based on an analysis of official public speeches and documents (in total 62), examines the Concertación’s rationale and political project in school education. The coalition’s aim was to move from a “free market” to a regulated market, through a balanced formula that—while preserving the market framework—added greater state investment, compensatory programs, and performance accountability measures. Hypotheses circulated in the country that the Concertación did not deliver further transformations due to legal constraints, international pressure, and “conflict phobia”. Despite historical limitations and internal disputes, the research provides evidence that the government’s educational program, in large part, was true to its own system of thinking. Hence, the center-left coalition did not maintain the market-based model in spite of its governmental rationality, but because of it.
The Gas-Dynamic Efficiency Increase of the K-300 Series Steam Turbine Control Compartment
Authors:   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Rusanov Andrii V. , Shvetsov Viktor L. ,   Joint-Stock Company Turboatom, Kosianova Anna I. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Bykov Yurii A. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Pashchenko Natalia V. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Chuhai Maryna O. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Rusanov Roman A. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU
Published: January 2021

The paper proposes ways to increase the efficiency of nozzle control for steam power turbines of the K-300 series, that, along with the K-200 series turbines, form the basis of thermal energy in Ukraine. The object of study is considered to be the control compartment (CC) of the high-pressure cylinder (HPC) of the K-325-23.5 steam turbine. In the paper, the calculation and design of the control compartment of the steam turbine was performed using the complex methodology developed in IPMach NAS of Ukraine, that includes methods of different levels of complexity, from one-dimensional to models for calculation of spatial viscous flows, as well as analytical methods for spatial geometries of flow parts description based on limited number of parameterized values. The complex design methodology is implemented in the IPMFlow software package, which is a development of the FlowER and FlowER–U software packages. A model of a viscous turbulent flow is based on the numerical integration of an averaged system of Navier-Stokes equations, for the closure of which the two-term Tamman equation of state is used. Turbulent phenomena were taken into account using a SST Menter two-parameter differential turbulence model. The research was conducted for six operation modes in the calculation area, which consisted of more than 3 million cells (elementary volumes), taking into account the interdiscand diaphragm leakage. According to the results of numerical studies of the original control compartment of the K-325-23.5 steam turbine, it is shown that the efficiency in the flow part is quite low in all operation modes, including the nominal one (100% power mode), due to large losses of kinetic energy in the equalization chamber, as well as inflated load on the first stage. On the basis of the performed analysis of gas-dynamic processes, the directions of a control compartment flow part modernization are formed and themodernization itself is executed. In the new flow part, compared to the original one, there is a favorable picture of the flow in all operation modes, which ensures its high gas-dynamic efficiency. Depending on the mode, the efficiency of the control compartment increased by 4.9–7.3%, and the capacity increased by 1–2 MW. In the nominal mode (100% mode) the efficiency of the new control compartment, taking into account the interdisc and overbandage leakage, is 91%.
Integral Thermo-Anemometers for Average Temperature and Airflow Measurement in Ducts, at Anemostat Outlets and in Ventilation Grilles
Authors:   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Tsakanian Oleh S. , Koshel Serhii V. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU
Published: January 2021

When creating ventilation systems, it is important to correctly calculate the volumes of air inflow and outflow. If an error is made in the calculation or a redistribution of air flows is required, measurements are indispensable. The existing methods for determining the air flow rate by using point measurements in the cross-section are laborious and time-consuming, and taking readings at different time points introduces a significant error into the result. A. M. Pidhornyi Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine has developed a new hot-wire anemometer whose use greatly simplifies the measuring process. This device allows one to measure the average values of temperature and air velocity (flow rate) in the cross-section of air ducts or at the inlets and outlets of grilles and anemostats, and can be used in real time to monitor and control air flow rate and temperature in ventilation systems. The probe of the hot-wire anemometer is a metal shell with guides on which a sensitive element is laid. Its principle of operation is to change the heat transfer coefficient at different air leakage velocities. The anemometer is preliminarily calibrated in laboratory conditions at various velocities. There has been obtained a calibration dependence that can be used to measure the air flow rate at the inlets and outlets of air distribution devices and directly in the air ducts. To improve the measurement accuracy, it is necessary to provide the 90° angle of airflow leakage on the hot-wire anemometer probe. For this, special air collectors and air flow rectifiers are used.
Assessment of Residual Service Life of Cast Bodies of Control Valves of 220 MW Power Units
Authors:   National Technical University of Ukraine Igor Sikorsky Kyiv Polytechnic Institute, Chernousenko Olha Yu. , Ryndiuk Dmytro V. ,   National Technical University of Ukraine Igor Sikorsky Kyiv Polytechnic Institute, Peshko Vitalii A. ,   National Technical University of Ukraine Igor Sikorsky Kyiv Polytechnic Institute
Published: January 2021

In the regulatory documents of the Ministry of Energy and Coal Industry of Ukraine, the beyond-design operating life of the high-energy equipment of 220 MW power units is limited to the operating life of 220 thousand hours and 800 start-ups. To date, the high-temperature cast bodies of the control valves for the high- and intermediate-pressure cylinders of the K-200-130 200 MW steam turbines of DTEK Lugansk TPP have operated about 305–330 thousand hours with the total number of start-ups from 1438 to 1704, which exceeded the beyond-design service life characteristics. Therefore, it is necessary to assess the residual operating life of the control valve bodies of the high- and intermediate-pressure cylinders of K-200-130 steam turbines in order to determine the possibility of their further operation. These calculations were carried out on the basis of our earlier studies of the thermal and stress-strain states of cast turbine equipment. This paper establishes the values of stress intensity amplitudes, the values having been reduced to a symmetric loading cycle for the most typical variable operating modes. Using the experimental low-cycle fatigue curves for the 15Kh1M1FL steel, we established the values of the permissible number of start-ups and the cyclic damage accumulated in the base metal. We also determined the value of the static damage accumulated in the course of stationary operating modes according to our previously obtained experimental data on the long-term strength of the 15Kh1M1FL steel. The calculations showed that the total damage to the control valve bodies of the K-200-130 steam turbine of power unit 15 of DTEK Lugansk TPP is 97 and 98%. The residual operating life of the metal of the control valves of high-pressure cylinders is practically exhausted, being equal to 10 thousand hours. The residual life of the control valves of intermediate- pressure cylinders is 7 thousand hours, i.e. it is also practically exhausted, with safety factors for the number of cycles and strains at the level of 5 and 1.5, as well as the permissible 370,000 operating hours of the metal. With an increase in the permissible operating life of the metal to 470 thousand hours, according to experimental studies of Igor Sikorsky KPI, the total damage to the metal of cast valve bodies is reduced to 80%, and the residual metal life increases to 79,000 h and 75,000 h for the control valves of the high- and intermediate-pressure cylinders, respectively.
Stress-Strain State of Steam Turbine Lock Joint Under Plastic Deformation
Authors:   Joint-Stock Company Turboatom, Palkov Ihor A. , Shulzhenko Mykola H. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU
Published: January 2021

The stress-strain state problem for the lock joint of the rotor blades of the first stage of the medium-pressure cylinder under plastic deformation is solved. When solving the problem, the theory of elastic-plastic deformations is used. The problem is solved using two different approaches to specifying plastic deformation curves. The applicability of using a simpler bilinear approximation instead of the classical multilinear one is estimated. Based on the example of solving this problem, the time required to perform the calculation with the use of the bilinear and multilinear approximations is shown. Comparison of the results obtained in the form of the distribution of plastic deformations, equivalent stresses, and contact stresses over support pads made it possible to assess the difference when the two types of approximation are used. The obtained result error value when using the bilinear approximation made it possible to draw conclusions about the applicability of this approach to the processing of plastic deformation curves for solving problems of this kind. The problem is solved using the finite element method. To objectively assess the effect of plastic deformation on the redistribution of loads in the lock joint, a finite element model is used, obtained when solving the problem of the thermally stressed state of the rotor blade lock joint. The distribution of contact stresses in the lock joint is shown. The results are compared with those obtained earlier when solving the problem of thermoelasticity. Significant differences in the level of contact stresses are noted. Results of the computational assessment of the stress-strain state of the lock joint of the rotor blades of the first stage of the medium-pressure cylinder of a steam turbine are presented, which allow characterizing the degree of relaxation and redistribution of stresses in the structure in comparison with the results obtained earlier when solving the problem of thermoelasticity. Conclusions are made about the economic viability of using the calculation methods presented.
Physical Model and Calculation of Face Packing Seals
Authors:   Pukhov Institute for Modelling in Energy Engineering of NASU, Shevchenko Serhii S.
Published: January 2021

Increasing the reliability and service life of dynamic-pump shaft seals is the most important requirement for their creation. The most common type of seals is still traditional stuffing box seals, which are controlled leakage assemblies that are periodically restored during operation. A radical change in the design of standard stuffing box seals is the transition to face packing seals with a constant pressure against the packing. It is shown that face packing seals can successfully combine the advantages of mechanical face seals and the simplicity and relatively low cost of traditional stuffing box seals. Mechanical face seals, in which one of the packing rings is replaced by a stuffing box packing, have advantages that significantly expand the application of traditional stuffing box seals. A scheme and a physical model of the face packing seal operation are described. During the operation of the seal, the packing is pushed away from the mating metal surface by the pressure of the medium. In this case, a confusor gap is formed, the length of which is proportional to the ratio of the sealed pressure to the pre-compression pressure of the packing. The calculation of the distribution of the hydrostatic pressure and gap along the radius of the face joint of the seal is presented. The irregularity of the contact pressure along the radius, caused by the pressing out of the packing by the sealed inlet pressure, causes premature wear of the overloaded areas of contact surfaces. Expressions are proposed for estimating friction power losses in face packing seals. It is shown that these losses are significantly lower in comparison with the power losses in traditional stuffing box seals. Assessment of the thermal state of face packing seals has been carried out. An expression has been obtained for determining the flow rate that provides the average contact-surface temperature not exceeding the permissible value. Our studies have shown that the load factor of face packing seals, in contrast to mechanical face seals, must be close to unity. The obtained dependencies make it possible to calculate face packing seals at their design stage.
Contact Deformation of the Pipeline Sealing Unit
Authors:   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Kostikov Andrii O. , Palkov Serhii A. ,   Joint-Stock Company Turboatom
Published: January 2021

The features of the turbine steam line sealing unit stress-strain state are examined on the basis of the usage of a three-dimensional design model of the construction and contacting surfaces. The considered unit consists of the pipeline, a crimp casing consisting of two halves with an outlet in one of them, and a gasket. A mathematical model that takes into account the mechanical loads caused both by the internal steam pressure on the steam line wall and by the casing fasteners tightening has been formed. This model also includes contact interaction in the sealing unit on the contact surface of the pipeline, the upper and lower halves of the casing. This contact problem solving method, based on the application of the finite element method, is proposed. The finite element model is based on twenty-unit three-dimensional finite elements with three degrees of freedom at each unit. Eight-unit contact finite elements were used to describe contact and sliding between surfaces. Contact conditions are taken into account with the penalty method usage. The verification of the model and the software that implements the proposed method is carried out by comparing the calculation results and experimental data obtained on the physical model of the pipeline. The physical model was made from a low-modulus material with full geometric similarity and the same ratio of the elastic moduli of materials as in a real object. The stress-strain state of the sealing unit of a real pipeline in a three-dimensional setting was determined and the most stressed zones in the unit, which require increased attention during the design and operation of pipelines and their connections, were identified. The developed approach and software make it possible to determine the contact pressure for the horizontal joint flanges of highly stressed cylinder bodies of powerful steam turbines, which helps to avoid a large number of expensive experimental studies.
Investigation of the Electrolysis Process of Obtaining Hydrogen and Oxygen with Serial and Parallel Connection of Electrons
Authors:   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Shevchenko Andrii A. , Zipunnikov Mykola M. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Kotenko Аnatolii L. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Chorna Natalia A. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU
Published: January 2021

This paper presents theoretical and experimental studies of the process of electrochemical generation of hydrogen and oxygen with a parallel and serial connection of electrodes in one electrolyte volume. This study is based on the laws of conservation of mass, thermodynamics, electrical engineering, electrochemistry, using data obtained from the methods of mathematical and physical modeling. Data on the development and research of two designs of electrode assemblies, namely, with a parallel and series connection of electrodes, and with the subsequent placement of each assembly in one electrolyte volume. Experimental and calculated data revealed the regularities of the electrochemical reaction of decomposition of the liquid electrolyte into hydrogen and oxygen, the distribution of voltage when the electrodes are connected in parallel and in series in one electrolyte volume. A change in the electric potential between the internal electrodes was also found. Voltage measurement was performed from electrode 1 to electrode 4. The results of experimental studies were displayed graphically. The graphs show that the voltage at the terminals of the internal electrodes is lower than necessary for the electrochemical reaction of decomposition of the liquid electrolyte with the generation of gaseous hydrogen and oxygen. To implement the concept of placing a series (bipolar) connection of electrodes in one electrolyte volume, it is necessary to focus on the design of the electrolyzer that will be able to disconnect the electrodes electrically and provide galvanic isolation between them (separately isolated electrolyte volumes for each electrode pair). This will increase the operating pressure of the generated hydrogen and oxygen to 20.0 MPa, reducing the current load of the electrolysis process when using alternative energy sources.
Optimization of Systems Repair Plans and Assessment of the Useful Life of Nuclear Power Plant Equipment
Authors:   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU, Zevin Leonid I. , Krol Hennadii H. ,   A. Pidhornyi Institute of Mechanical Engineering Problems of NASU
Published: January 2021

This paper presents a computer-aided method of planning the volumes of repairs of systems of nuclear power units and a method for calculating their gamma-percentile life. This planning is carried out on the basis of predicting the reliability indicator, the probability of no-failure operation for a certain time period, with the gamma-percentile life of the equipment being determined by solving the corresponding equations. The tasks considered are related to an important energy problem of extending the operation of nuclear power units. Its importance is determined mainly by economic feasibility: it is cheaper to assess the useful life of a nuclear power unit and, on this research basis, extend its operation, than create a new unit. It is also shown that the calculation of the probability of a radiation accident at a nuclear power unit is associated with the results of planning the repairs of its systems, with assessment of its useful life. An optimization problem is formulated: it is required to find such a plan for the volumes of repair of a system that, with limited repair costs, its reliability indicator for a given duration deviates least from the maximum permissible value. The solution to the problem is based on calculating the structural reliability of the system. A graphological image of the system is built in the form of a composition of graphological images of typical structures. After the reliability indicator of typical structures has been calculated, the structures are replaced with individual structural elements, which makes it possible to simplify the initial graphological image of the system in a computational scenario and calculate its reliability indicator. The determination of the repair volume is carried out by applying a version of the coordinate-wise optimization method. To assess the gamma-percentile life, a model is adopted, in which the recoverable equipment components have an unlimited life, although, of course, they "age", and the non-recoverable components spend their life up to the level when their replacement becomes conditioned by the violation of the requirement for the maximum permissible value of the system reliability indicator. Estimates of the gamma-percentile life of the equipment are calculated by planning system repairs on a sequence of intervals of annual energy production by a nuclear power unit.
PENDEKATAN GROUP WORK DALAM PRAKTIK PEKERJAAN SOSIAL: PENGALAMAN PEKERJA SOSIAL DI LEMBAGA KESEJAHTERAAN SOSIAL (LKS) DI INDONESIA
Authors: Napsiyah Siti , Zaky Ahmad
Published: January 2021

Abstract. Group work in social work practice is one of methods for social workers’ intervention to help the client to cope with their social problems. This research aims to discuss the importance of group work method in social work practices: How they use group work methods, what are the steps of group development process; what are ethical and cultural issues occur during the process? Research method used is qualitative method. Data collection of the research is throughout interview as well as online survey. This research uses also document analysis throughout search engine such as google scholar and google form. The result of the study shows that group work becomes strategic method for social workers to help the client to solve their problems. This study also confirms social workers in social welfare institutions (LKS) in Indonesia are mostly use group work method. Interestingly, this research discuss the issue of cultural and religious ethics in the context of group process in Muslim group and community.   Abstrak. Pendekatan group work dalam praktik pekerjaan sosial merupakan salah satu pendekatan yang menjadi andalan praktik profesi pekerja sosial dalam memberikan pertolongan kepada klien (individu, kelompok, komunitas, dan organisasi) dalam menyelesaikan masalah. Penelitian ini berusaha untuk menjelaskan tentang metode group work dalam praktik pekerjaan sosial, bagaimana pekerja sosial menggunakan metode group work dalam menyelesaikan permasalahan klien, bagaimana dinamika kelompok muncul dalam proses group work, dan mendiskusikan tentang bagaimana isu etik dan sensitivitas budaya muncul saat proses pelaksanaan group work. Jenis penelitian yang dipilih adalah penelitian kualitatif deskriptif. Studi dokumentasi dilakukan dengan menelusuri sumber-sumber pada mesin pengindeks dan data base yang mendukung open access, seperti google cendekia (google scholar), academia.edu, dan lain-lain. Penelitian juga dilakukan dengan menggunakan survey kepada pekerja sosial melalui google form. Hasil penelitian menunjukkan bahwa metode group work dinilai sebagai pendekatan yang sangat penting bagi pekerja sosial dalam menyelesaikan permasalah sosial yang bersifat kelompok. Hasil penelitian ini juga menunjukkan bahwa dalam proses pelasaksanaan metode group work terdapat dinamika kelompok dan sensitivitas sosial dan agama. Sehingga isu integrasi keilmuan, keislaman dan keindonesiaan menjadi menarik dalam diskusi paper ini.
KEHIDUPAN ANAK TERLANTAR DI LKSA YUDA MANDIRI SOMBA OPU
Authors: Syamsudin Syamsudin
Published: January 2021

Abstract. The life of an abandoned child certainly needs protection so that he can be independent. The article aims to analyze the living conditions of neglected children who have been coached by social workers and supervisors at the Yuda Mandiri Somba Opu Child Welfare Institution. The type of research is descriptive qualitative, obtaining data from informants through in-depth interviews and observations, to analyze data by way of data reduction, data presentation and drawing conclusions. The results obtained regarding the life of street children are the pre-Karangtina situation through assessment, the availability of dormitories, in school, mental guidance and moral guidance, group and individual recitation in the afternoon. Abstrak. Kehidupan anak terlantar tentu membutuhkan perlindungan agar ia bisa mandiri. Artikel bertujuan untuk menganalisi kondisi kehidupan anak terlantar yang selama ini di bina para pekerja sosial dan pembina Lembaga Kesejahteraan Sosial Anak Yuda Mandiri Somba Opu. Adapun jenis penelitian adalah deskriptif kualitatif, perolehan data dari informan melalui wawancara mendalam maupun observasi, untuk menganalisis data dengan cara reduksi data, penyajian data dan penarikan kesimpulan. Hasil yang diperoleh tentang kehidupan anak jalanan yaitu situasi pra karantina melalui assessment, tersedianya asrama tempat tinggal, di sekolahkan, pendampingan bimbingan mental dan pembinaan akhlak, pengajian di sore hari secara berkelompok maupun individu.