bluuebunny/crossref_metadata_2025 huggingface dataset:
The superiority of fuzzy exponential faimly distributions in measuring the reliability of the machines
Authors: Shamkhi Jaber Adnan , Fahm Talal Safa
Published: February 2018

The study of the efficiency of the reliability of systems or productive systems in scientific life has a significant and important role in the scientific and technological development of these systems. This study deals with the superiority of mass fuzzy exponential distributions (exponential, wibble, kama, natural logarithmic) in measuring the reliability of the machines of the successive system.

       The applied study included data taken from the Diesel Station north of Diwaniyah, which is the time of failure and taken to a single block consisting of five machines operating respectively.

      The most important results of the study are that the data follow the distributions of the mass fuzzy exponential and the best distribution is the natural distribution logarithmic as the owner of the highest reliability as it turns out that the machines decreased significantly and largely because of the lack of preventive maintenance of these machines because of lack of equipment backup materials as a result of the austerity policy as well as the poor fuel used in operation.
Simulation Methods of Multivariate Normal Distribution
Authors: Abdul Abbas Abidy Fadhil , Hussein Battor Ali , Abdul Reza Baqir Esraa
Published: February 2018

:. In this paper, we are studying three simulation methods to generate observation for multivariate normal distribution, and these methods are: Matlab mvnrnd, decomposition and conditional methods, and we put simulation programs for each method by Matlab 2015a software, and comparison between these methods by depend on many criterions as MSE, AIC, skw, kur. As well as the run speed criterion for each method to get the best method.
Adaptación de Alumnos según estilos de Afrontamiento Individual al Primer año de la Carrera de Arquitectura
Authors: Cañete Islas Omar Eduardo
Published: February 2018

El desafío y aporte en esta propuesta es aplicar, mediante técnicas de auto reporte, tanto una clasificación del estilo primario y secundario de afrontamiento, en un contexto de desempeño grupal de alumnos de primer año de la carrera de arquitectura de la Universidad de Valparaíso, en el   marco de los criterios y objetivos de autorregulación promovidos por la Universidad a través de la Unidad de división Académica.  Con esto, se espera obtener medidas cuantitativas y cualitativas de la evolución individual y cambios en los procesos de autorregulación del aprendizaje, asociado a la experiencia de trabajo grupal.
Estrategias Constructivistas Aplicadas por el Docente para el Aprendizaje de la Física en el Nivel Superior
Authors: Páez Pereira Avilner Rafael
Published: February 2018

El objetivo de este estudio consistió en determinar las estrategias constructivistas aplicadas por el docente para el aprendizaje de la física en la carrera Educación Matemática y Física en la Universidad Nacional Experimental “Rafael María Baralt”. La investigación fue de tipo descriptiva, con diseño de campo, documental, prospectiva y transversal. Se utilizaron como instrumentos un cuestionario de respuestas policotómicas de 34 ítems dirigido a los docentes, así como una prueba objetiva de preguntas cerradas de selección simple con 21 ítems, destinada a los estudiantes. Los resultados obtenidos evidencian que los profesores, no aplican en su mayoría, las estrategias constructivistas más adecuadas para lograr en sus estudiantes aprendizajes significativos, puesto que en un 60% los educandos no han alcanzado una formación idónea sobre la disciplina, además que los facilitadores frecuentemente no consideran, estrategias para el procesamiento de la información, el contexto donde se van a desarrollar las mismas y los estilos de construcción del conocimiento del aprendiz.
E-Learning como Herramienta de Capacitación Alternativa Humanística
Authors: Camacho Quintero Carlos Liborio
Published: February 2018

El objetivo de la investigación es elaborar una herramienta e-learning de capacitación alternativa en la Dirección de Recursos Humanos del Estado Bolivariano de Mérida, específicamente en la Gobernación cuyo propósito es proponer un programa de capacitación para los trabajadores. El proceso está circunscrito a un paradigma cuantitativo, bajo un modelo Operativo Factible. La técnica utilizada para la recolección de la información fue la encuesta y el instrumento utilizado el cuestionario; la confiabilidad fue determinada mediante el coeficiente de Alpha de Cronbach el cual genero 0.98 alta confiabilidad y su validación se hizo con el aporte de tres expertos. Los resultados generaron datos que fueron analizados y graficados, lo cual permitió concluir que la institución está en condiciones para aplicar un modelo de capacitación sustentado en e-learning, recomendándose considerar la presente propuesta con fines de lograr mejoras significativas en la gestión.
Motivación Laboral. Elemento Fundamental en el Éxito Organizacional
Authors: Peña Rivas Humberto Coromoto , Villón Perero Sabina Gisella
Published: February 2018

El presente estudio tiene como objetivo analizar la influencia de la motivación en el talento humano y determinar los factores que tienen mayor impacto en el desempeño laboral. La investigación se desarrolló en base a una metodología hermenéutica, que inició en la revisión bibliográfica-documental permitiendo obtener las referencias teóricas, criterios básicos y relevantes acerca de la motivación laboral, de tal manera que la obtención, identificación y descripción de los datos facilitó  el logro del objetivo planteado, obteniendo como resultado que un empleado motivado brindará a la empresa un mejor desempeño, desarrollará sentido de pertenencia, fidelidad a lo que hace, reflejando como consecuencia beneficios tanto para la empresa como para los empleados concluyendo que el comportamiento de un empleado en la organización, depende de los factores motivacionales que se apliquen a fin de satisfacer sus necesidades básicas como son las buenas relaciones laborales, la satisfacción laboral, clima laboral positivo y los resultados de la satisfacción laboral; actualmente, motivar de manera acertada   se ha convertido en una actividad que logrará que los empleados creen un sentido de pertenencia y la actividad que realiza cada uno de ellos, arroje resultados positivos a fin de contribuir con éxito en lo que hace la organización. Como elemento fundamental en el desarrollo asertivo de la organización, la motivación guarda una estrecha relación con la satisfacción laboral, las relaciones laborales y el entorno laboral, sin dejar de lado al rol del gerente quien juega un papel especial, al momento de llevar la responsabilidad de dirección y de aplicar las estrategias más adecuadas de motivación dentro de una organización empresarial.
Wind energy storage by pumped hydro station
Authors: NACİRİ Mariem , AGGOUR Mohammed , AİT AHMED Wassima
Published: February 2018

During the next decades, the electricity generation
sector will know significant changes. This is mainly due to the increase in
demand, with the limitation of traditional resources such as fossil fuels and
the development of renewable energy particularly the proliferation of wind
farms. Hydroelectric pumped-storage power plants, which store large amounts of
energy and quickly compensate the power fluctuations, will then play a key
role. It is therefore essential to find ways to fully optimize the performance
of this type of plant. The main objective of this work is to study and choose
the right place according to different criteria, topographical, geographical in
order to install a pumped hydro station we try to size. All this is in order to
ensure network stability. Such a study requires two main pumped hydro stations,
namely the theoretical development and case study part. With the arming out of
the three wind farms developed by Nareva holding, a major leader company in the
domains of the energy and the environment, Akhfennir and Foum El Oued in the
South of Morocco, and Haouma in the north of the country near to Tangier, these
three parks, of a total capacity of 203 MW. Storing the surplus of the wind
produced energy became a priority, hence we led a detailed study on six sites
on various region of Morocco to install a hydraulic pumping station of a power
of 50MW.The pumped hydro station of Abdelmoumen is situated in the upstream of
the restraint of the dam Abdelmoumen on the Wadi Issen in approximately 70 kilometres
in the Northeast of the city of Agadir. The study of the sizing of the pumped
hydro station of Abdelmoumen led to us to the conception of a station of 50MW
of power for a height difference of 800m separating both upper and lower
reservoirs whose volumes are respectively 2 610 000 m3 and 749 700 m3.
We conceived a Pelton turbine with a debit of turbinage of 8 m3/s, a
pump spin-dries radial road of 2,4 m3 /s and penstock of 6 691m of
1m of diameter.
Modeling and optimization of a superstrate solar cell based on Cu2ZnSn(SxSe1-x)4/ZnS structure
Authors: Aissat Abdelkader , Arbouz Hahet , Vilcot Jean Pierre
Published: February 2018

The
Kestrite semiconductor material Cu2ZnSnSe4 (CZTSe) is
believed to be a suitable candidate for replacing the CuIn1-xGaxSe2
(CIGS) absorber for the abundance and the non-toxicity of its components.
However, the record efficiency of solar cells based on this material reaches
11% which is lower than the conversion efficiency of the CIGS based solar cell
for which the efficiency has reached 25%. The aim of this study is to model and
optimize the electrical performances of a superstrate type solar cell based on
the kestrite material Cu2ZnSn(SxSe1-x)4
(CZTSSe). The goal is to investigate the effect of mixing the sulfide (S) component with selenide
(Se) on the conversion efficiency η, band gap Eg open
circuit voltage Voc, short circuit current density Jsc,
fill factor FF and maximum power density P of the device, through
the evaluation of their behavior as a function of the ratio S/(S+Se),
which represents the concentration of sulfur in the absorber material CZTSSe.
It is also shown in this work, through the calculation of the mismatch strain ε
at the interface between the absorber and the buffer layers, that the zinc
sulfide (ZnS) is a more appropriate buffer than cadmium sulfide (CdS) for the
CZTSSe absorber. The effect of strain at the interface buffer/absorber on the
bandgap energy of CZTSSe and then on the cell performances is evaluated. This
evaluation is based on the strain theory in order to obtain more realistic
results close to experimental results. It is noted that adding 72% of Sulfur in
the absorber material, meaning that x=0.72, increases the efficiency to
13.1% therefore an improvement of 21.3% is obtained compared to the efficiency
of the CZTSe solar cell with a strain equal to 0 meaning no deformation, Jsc=
15.35mA/cm², Voc= 0.800 V, FF = 74.1% and Pmax=9.45mW/cm².
Control of dual stator induction generator integrated in wind energy conversion system
Authors: BENAKCHA Meryem , Benalia Leila , Ameur Fatima , Tourqui Djamel Eddine
Published: February 2018

This paper deals with the modeling and the control of a dual stator induction generator (DSIG) integrated into a wind energy conversion system with a variable speed wind turbine. DSIG is increasingly used because of its advantages in better reliability and supply division. It consists of two fixed three-phase stator windings displaced with an electrical angle 𝛼𝛼. To minimize the harmonic distortion (THD), the objective of this work is to study the influence of the angle between these two stator windings on the grid generated current quality. To improve the performance of the system, the proposed control is demonstrated through an illustrative simulation.
Bel ağrısı nedeniyle polikliniğimize başvuran hastalarda skolyoz sıklığı ve Cobb açısı değerlerinin yaş ve cinsiyet ile ilişkisi.
Authors: ATILGAN ÇELİK Ayşe , COŞKUN Semra , KILINÇ Onur , YILDIRIM Adem
Published: February 2018

Amaç: Bu çalışmanın amacı
polikliniğimize bel ağrısı ile başvuran hastalarda skolyoz sıklığını saptamak
ve Cobb açısı ile yaş ve
cinsiyet arasında ilişkisi olup olmadığını araştırmaktı.Yöntem:
Bel ağrısı ile
polikliniğimize başvuran 10837 hastanın verileri retrospektif olarak
değerlendirildi. Öykü ve fizik muayane bulgularına göre skolyozdan şüphelenilip
skolyoz grafisi çektirilen 130 hastanın verileri çalışmamıza dahil edildi.
Hastaların omurga eğrilik dereceleri radyografik olarak anterio-posterior yönde
tüm omurgayı görmeyi sağlayan skolyoz grafisi üzerinde Cobb açısı ölçümü
yöntemi ile değerlendirildi. Cobb açısı 10 derece üzerinde olan hastalar
skolyoz olarak değerlendirildi. Skolyoz sıklığı, Cobb açısı değerinin yaş ve
cinsiyet ile olan ilişkisi araştırıldı.Bulgular:
Çalışmaya alınan
130 hastanın 80 tanesi kadın (%61,5), 50 tanesi ise erkek idi (%38,5). Cinsiyete göre yaş ortalamaları
arasında istatistiksel olarak anlamlı fark bulunamadı. 111 hastada (%85,4)  Cobb açısı <10 derece, skolyoz tanısı alan
19 hastada ise (%14,6) ≥10 derece olarak ölçüldü. Skolyoz sıklığı binde 1,75
idi. Çalışmaya alınan kadın ve erkek hastaların Cobb açısı ortalamaları
sırasıyla 5,81 ± 4,22 ve 5,32 ± 4,29 idi. Hastaların Cobb açısı ölçüm
sonuçlarının cinsiyete göre dağılımına bakıldığında anlamlı fark olmadığı
görüldü. Yaş ile
Cobb açısı arasındaki ilişkisi incelendiğinde pozitif yönde zayıf bir
korelasyon olduğu görüldü.

Sonuç:
Bel ağrısıyla
başvuran hastalarda skolyoz varlığı göz önünde bulundurulmalı,  hastanın yaşı da göz önünde bulundurularak
uygun radyolojik istemler yapılmalıdır.
Market Turnover of Nepalese Stock Market
Authors: Lamichhane Baburam
Published: February 2018

Securities market turnover is one of the major behavioral phenomena of stock market. It always depends on the demand and supply of the securities, so the market turnover assumes a number of trading share units, values of share turnover and percentage share value of stocks. This paper is concerned to analyze the different areas of stock units’ turnover and value coverage of stock market .descriptive research design is applied for analyzing the stock market condition. The coverage of share units and share of value weight is analyzed of Nepal stock exchange market economy.The Journal of Nepalese Business Studies Vol. X No. 1 December 2017, Page: 96-100
Mannheim Peritonitis Index (Mpi) Score as A Predictor of Outcome in Patients with Secondary Peritonitis
Authors: Joshi Pravin , Poudel Rajesh , Chandra Kailash
Published: February 2018

INTRODUCTION: Secondary bacterial peritonitis from hollow viscous perforation is one of the common surgical emergencies and carries higher mortality. Several scoring systems are applied to predict the outcome of patients with perforation peritonitis. Mannheim Peritonitis Index (MPI) is one among many. Our aim of the study is to evaluate Mannheim peritonitis Index for predicting the outcome in patient with secondary bacterial peritonitis. MATERIALS AND METHODS: A retrospective study was conducted in the Department of General Surgery, Universal College of Medical Sciences, Bhairahawa from February 2012 to July 2013. All patients clinically diagnosed as peritonitis and who underwent laparotomy were included in the study. MPI score of all the study patients were calculated and categorized into three groups depending upon the score; less than 15, 15-25 and more than 25. Mortality of patients from each group was calculated and predictive value of each factor was determined.  RESULTS: Total 60 patients were included in the study. Forty-four were male and sixteen were female. There were total five mortalities. All were of above 50 years age group. Patients beyond 50 years of age had a significantly higher (p = .005) probability of dying in the early post-operative period. MPI score more than 15 was not statistically significant (p = .06), patients with MPI more than 25 had more probability of dying, hazard ratio (HR 3.4 with 95% CI).Journal of Universal College of Medical Sciences (2016) Vol.04 No.02 Issue 14, page: 6-9
Austenitic Stainless Steel Bolt Failure by Stress Corrosion Cracking
Authors: Neidel A. , Gädicke T. , Hartanto V. , Wallich S. , Wöhl E.
Published: February 2018

During a minor inspection of a heavy-duty gas turbine engine, the hexagonal head of a bolt used for fixing a metal plate in the air intake was found on the floor of the air intake casing [1, 2]. The respective washer was not found. It is believed to have been ingested into the engine, having caused moderate compressor damage. The inspection was started after 83.500 operating hours. Only one fractured bolt was found. The subject bolt fractured due to stress corrosion cracking (SCC), induced by pitting corrosion and possibly assisted by crevice corrosion.
Can coercion be justified when it benefits the poor? The case of commercial surrogacy industry in India
Authors: Asirvatham Packiaraj
Published: February 2018

Commercial surrogacy in India is a booming industry however the raising number of poor illiterate women's participation as commercial surrogate poses serious question of coercion, on the other hand it economically empowers them. In this context, this article analyses the crucial question, can coercion be justified when it benefits the poor by investigating commercial surrogates’ life stories and looking into the various types of coercion discreetly operates. It concludes with few recommendations which can help in empowering poor commercial surrogates who involved in commercial surrogacy industry in India.
An African Perspective on Surrogacy and the Justification of Motherhood
Authors: Aina Akande Michael
Published: February 2018

Surrogacy as a practice is supported by science, technology, morality and legality. It follows that the issues concerning it cut across all facets of life. And different arguments have being advanced for and against this practice. The belief espouse in this paper is that one cannot discuss successfully the moral, the science or the legality of surrogacy without delving into the cultural question of who is a mother. In other words, it is possible to have simple scientific and legal understandings of the practice and still disagree on the cultural level because of its stronger emotional appeal. The purpose of this work is to expose the Yoruba-African religio-cultural beliefs that have bearing on the understanding of motherhood or ownership of a child. This will be done through a critical analysis of Yoruba cultural beliefs about personhood and the metaphysical underpinning between birth and the ontology of life itself. Theargument here is that given some Yoruba ontological belief about life, motherhood and personhood it may be difficult for the products of surrogacy to fit-in into the society in terms of personal and social development. This work goes further to recommend that cultural beliefs should be taking into consideration when making laws to guide surrogacy in order to avoid conflict between the mothers and the child.
BBS News
Authors: Lasker Shamima
Published: February 2018

Training programme on “Research Methodology”Planning, Monitoring & Research Division of DGHS with technical support of Bangladesh Bioethics Society (BBS) and American University of Sovereign Nation (AUSN, USA) organized a three days Training programme on “Research Methodology” on 3-5 December, 2017 at Conference Room, DGHS (1st floor, Old Building). Graduation Ceremony: Following Members of BBS have been graduated from AUSN, USA in 2017 and honored by BBS through a programme.PhD (Bioethics, Sustainability and Global Public Health)Prof Shamima Parvin Lasker, Professor & Head of Anatomy, MH Samorita Medical College, Dhaka – She is the 2nd PhD holder and 1st Female PhD from AUSN. Master of Bioethics and Global Public Health Dr Tonmoy BiswasTanya AhmedTamjida Ahmed
Discontinuous Galerkin Finite Element Investigation on the Fully-Compressible Navier–Stokes Equations for Microscale Shock-Channels
Authors: Zingaro Alberto , Könözsy László
Published: February 2018

Microfluidics is a multidisciplinary area founding applications in several fields such as the aerospace industry. Microelectromechanical systems (MEMS) are mainly adopted for flow control, micropower generation and for life support and environmental control for space applications. Microflows are modeled relying on both a continuum and molecular approach. In this paper, the compressible Navier–Stokes (CNS) equations have been adopted to solve a two-dimensional unsteady flow for a viscous micro shock-channel problem. In microflows context, as for the most gas dynamics applications, the CNS equations are usually discretized in space using finite volume method (FVM). In the present paper, the PDEs are discretized with the nodal discontinuous Galerkin finite element method (DG–FEM) in order to understand how the method performs at microscale level for compressible flows. Validation is performed through a benchmark test problem for microscale applications. The error norms, order of accuracy and computational cost are investigated in a grid refinement study, showing a good agreement and increasing accuracy with reference data as the mesh is refined. The effects of different explicit Runge–Kutta schemes and of different time step sizes have also been studied. We found that the choice of the temporal scheme does not really affect the accuracy of the numerical results.
Do Coffee Polyphenols Have a Preventive Action on Metabolic Syndrome Associated Endothelial Dysfunctions? An Assessment of the Current Evidence
Authors: Yamagata Kazuo
Published: February 2018

Epidemiologic studies from several countries have found that mortality rates associated with the metabolic syndrome are inversely associated with coffee consumption. Metabolic syndrome can lead to arteriosclerosis by endothelial dysfunction, and increases the risk for myocardial and cerebral infarction. Accordingly, it is important to understand the possible protective effects of coffee against components of the metabolic syndrome, including vascular endothelial function impairment, obesity and diabetes. Coffee contains many components, including caffeine, chlorogenic acid, diterpenes and trigonelline. Studies have found that coffee polyphenols, such as chlorogenic acids, have many health-promoting properties, such as antioxidant, anti-inflammatory, anti-cancer, anti-diabetes, and antihypertensive properties. Chlorogenic acids may exert protective effects against metabolic syndrome risk through their antioxidant properties, in particular toward vascular endothelial cells, in which nitric oxide production may be enhanced, by promoting endothelial nitric oxide synthase expression. These effects indicate that coffee components may support the maintenance of normal endothelial function and play an important role in the prevention of metabolic syndrome. However, results related to coffee consumption and the metabolic syndrome are heterogeneous among studies, and the mechanisms of its functions and corresponding molecular targets remain largely elusive. This review describes the results of studies exploring the putative effects of coffee components, especially in protecting vascular endothelial function and preventing metabolic syndrome.
Plasmonic Physics of 2D Crystalline Materials
Authors: Torbatian Zahra , Asgari Reza
Published: February 2018

Collective modes of doped two-dimensional crystalline materials, namely graphene, MoS 2 and phosphorene, both monolayer and bilayer structures, are explored using the density functional theory simulations together with the random phase approximation. The many-body dielectric functions of the materials are calculated using an ab initio based model involving material-realistic physical properties. Having calculated the electron energy-loss, we calculate the collective modes of each material considering the in-phase and out-of-phase modes for bilayer structures. Furthermore, owing to many band structures and intreband transitions, we also find high-energy excitations in the systems. We explain that the material-specific dielectric function considering the polarizability of the crystalline material such as MoS 2 are needed to obtain realistic plasmon dispersions. For each material studied here, we find different collective modes and describe their physical origins.
Identification of Operating Parameters Most Strongly Influencing the Jetting Performance in a Piezoelectric Actuator-Driven Dispenser
Authors: Sohn Jung Woo , Choi Seung-Bok
Published: February 2018

This work identifies crucial operating parameters which most significantly influence the jetting performances of piezostack-driven non-contact dispensers. This is achieved through experimental investigation and statistical analysis. After introducing the configuration and operating principle of the piezoelectric jetting dispenser, an experimental setup is constructed in order to test the jetting performance, such as the dispensed amount. After selecting four significant operating parameters for the light-emitting diode (LED)-packaging process, two levels for each parameter are considered. Subsequently, the weight of a single dispensed dot is measured 100 times, and the average weight and standard deviation are calculated for each experimental set. The results are then statistically analyzed using a commercial software package. Finally, the crucial operating parameters which provide a low average weight and a minimum variation in the weight of a single dispensed dot are identified.
Lycopene in Beverage Emulsions: Optimizing Formulation Design and Processing Effects for Enhanced Delivery
Authors: Meroni Erika , Raikos Vassilios
Published: February 2018

Lycopene is a desired ingredient in food formulations, yet its beneficial effects on human health remain largely underexploited due to its poor chemical stability and bioavailability. Oil-in-water emulsions may offer multiple advantages for the incorporation and delivery of this carotenoid species. Engineering and processing aspects for the development of emulsion-based delivery systems are of paramount importance for maintaining the structural integrity of lycopene. The selection of emulsifiers, pH, temperature, oil phase, particle size, homogenization conditions and presence of other antioxidants are major determinants for enhancing lycopene stability and delivery from a food emulsion. Process and formulation optimization of the delivery system is product-specific and should be tailored accordingly. Further research is required to better understand the underlying mechanisms of lycopene absorption by the human digestive system.
PGC-1α-Derived Peptide Influences Energy in Normal Human Dermal Fibroblasts
Authors: Suchá Lenka , Šuláková Romana , Fryčák Roman , Dolečková Iva
Published: February 2018

Mitochondrial energy metabolism declines during aging. PGC-1α is a transcription coactivator that plays a key role in the regulation of energetic metabolism and mitochondrial biogenesis in the cells. The aim of this study was to compare the PPARGC1A gene expression level in normal human dermal fibroblasts (NHDF) derived from young and old donors. A PGC-1α-derived peptide was then synthetized and its ability to affect the PPARGC1A gene expression and mitochondrial function was tested. We assessed changes in PPARGC1A gene expression using quantitative RT-PCR. The effect of the PGC-1α-derived peptide on energy production was determined using an ATP bioluminescent assay kit. We also studied changes in mitochondrial membrane potential using JC-1 fluorescent dye and the level of reactive oxygen species (ROS) using DCFH-DA dye in NHDF cells after UVA/B irradiation alone and in combination with a peptide treatment. The PPARGC1A gene expression decreased in an aged human dermal fibroblast. The PGC-1α-derived peptide was synthetized and increased the PPARGC1A gene expression and ATP levels in cells. Furthermore, the mitochondrial membrane potential in UVA/B irradiated cells treated with the tested PGC-1α-derived peptide was increased compared to irradiated controls. Moreover, the ROS levels in UVA/B irradiated cells treated with the PGC-1α-derived peptide decreased. On the basis of our results, PGC-1α emerges as an interesting target to combat decreasing energetic metabolism in aging skin cells. Indeed, the PGC-1α-derived peptide increasing the PPARGC1A gene expression improved the mitochondrial function and increased energy production in the cells.
Step-Up Partial Power DC-DC Converters for Two-Stage PV Systems with Interleaved Current Performance
Authors: Zapata Jaime , Kouro Samir , Carrasco Gonzalo , Renaudineau Hugues
Published: February 2018

This work presents a partial power converter allowing us to obtain, with a single DC-DC converter, the same feature as the classical interleaved operation of two converters. More precisely, the proposed topology performs similarly as the input-parallel output-series (IPOS) configuration reducing the current ripple at the input of the system and dividing the individual converters power rating, compared to a single converter. The proposed topology consists of a partial DC-DC converter processing only a fraction of the total power, thus allowing high efficiency. Experimental results are provided to validate the proposed converter topology with a Flyback-based 100 W test bench with a transformer turns ratio n 1 = n 2 . Experimental results show high performances reducing the input current ripple around 30 % , further increasing the conversion efficiency.
Power Management of Islanded Self-Excited Induction Generator Reinforced by Energy Storage Systems
Authors: Nasser Nachat , Farrag Mohamed
Published: February 2018

Self-Excited Induction Generators (SEIGs), e.g., Small-Scale Embedded wind generation, are increasingly used in electricity distribution networks. The operational stability of stand-alone SEIG is constrained by the local load conditions: stability can be achieved by maintaining the load’s active and reactive power at optimal values. Changes in power demand are dependent on customers’ requirements, and any deviation from the pre-calculated optimum setting will affect a machine’s operating voltage and frequency. This paper presents an investigation of the operation of the SEIG in islanding mode of operation under different load conditions, with the aid of batteries as an energy storage source. In this research a current-controlled voltage-source converter is proposed to regulate the power exchange between a direct current (DC) energy storage source and an alternating current (AC) grid, the converter’s controller is driven by any variation between machine capability and load demand. In order to prolong the system stability when the battery reaches its operation constraints, it is recommended that an ancillary generator and a dummy local load be embedded in the system. The results show the robustness and operability of the proposed system in the islanding mode of the SEIG under different load conditions.
Determining the U-Value of Façades Using the Thermometric Method: Potentials and Limitations
Authors: Bienvenido-Huertas David , Rodríguez-Álvaro Roberto , Moyano Juan , Rico Fernando , Marín David
Published: February 2018

The thermal transmittance of building envelopes determines to a large extent the energy demand of buildings. Thus, there is a keen interest in having methods which can precisely evaluate thermal transmittance. From a scientific point of view, this study analyses the viability of the application of the thermometric method (THM), one of the most used methods in Spain. For this purpose, the test method has been improved by determining the adequate test conditions, the selection and installation of equipment, data acquisition and post-processing, and the estimation of uncertainty. We analyse eight case studies in a Mediterranean climate (Csa) to determine the potentials and limitations of the method. The results show that the values obtained through THM are valid under winter environmental conditions with relative uncertainties between 6% and 13%, while difficulties to perform the test in optimal conditions, and therefore to obtain valid results in warmer seasons, are detected. In this regard, the case studies which obtained a greater number of observations by performing the filtrate conditions were able to obtain representative results. Furthermore, there are significant differences depending on the kind of equipment and probes used during the experimental campaign. Finally, in warm climate regions a data filtrate can be considered for observations of a temperature difference higher than 5 °C, obtaining valid results for the case studies, although the rise in the thermal gradient can guarantee a greater stability of data.
Comparison of Positive Streamers in Liquid Dielectrics with and without Nanoparticles Simulated with Finite-Element Software
Authors: Velasco Juan , Frascella Ricardo , Albarracín Ricardo , Burgos Juan , Dong Ming , Ren Ming , Yang Li
Published: February 2018

In this paper, a comparison of positive streamer diffusion propagation is carried out in three configurations of oil transformers: mineral transformer oil, mineral oil with solid dielectric barriers, and a nanofluid. The results have been solved using a finite-element method with a two-dimensional (2D) axi-symmetric space dimension selected. Additionally, previous results from other research has been reviewed to compare the results obtained. As expected, it is confirmed that the nanoparticles improve the dielectric properties of the mineral oil. In addition, it is observed that the dielectric solid blocks the propagation of the streamer when it is submerged with a horizontal orientation, thus perpendicular to the applied electric field. The computer used, with four cores (each 3.4 GHz) and 16 GB of RAM, was not sufficient for performing the simulations of the models with great precision. However, with these first models, the tendency of the dielectric behavior of the oil was obtained for the three cases in which the streamer was acting through the transformer oil. The simulation of these models, in the future, in a supercomputer with a high performance in terms of RAM memory may allow us to predict, as an example, the best concentration of nanoparticles to retard the streamer inception. Finally, other dielectric issues will be predicted using these models, such as to analyze the advantages and drawbacks of the presence of dielectrics inside the oil transformer.
Performance Evaluation of Maximum Power Point Tracking Approaches and Photovoltaic Systems
Authors: Islam Haidar , Mekhilef Saad , Shah Noraisyah , Soon Tey , Seyedmahmousian Mehdi , Horan Ben , Stojcevski Alex
Published: February 2018

This paper elaborates a comprehensive overview of a photovoltaic (PV) system model, and compares the attributes of various conventional and improved incremental conductance algorithms, perturbation and observation techniques, and other maximum power point tracking (MPPT) algorithms in normal and partial shading conditions. Performance evaluation techniques are discussed on the basis of the dynamic parameters of the PV system. Following a discussion of the MPPT algorithms in each category, a table is drawn to summarize their key specifications. In the performance evaluation section, the appropriate PV module technologies, atmospheric effects on PV panels, design complexity, and number of sensors and internal parameters of the PV system are outlined. In the last phase, a comparative table presents performance-evaluating parameters of MPPT design criterion. This paper is organized in such a way that future researchers and engineers can select an appropriate MPPT scheme without complication.
A Load Flow Analysis for AC/DC Hybrid Distribution Network Incorporated with Distributed Energy Resources for Different Grid Scenarios
Authors: Khan Muhammad , Jamali, Saeed , Noh Chul-Ho , Gwon Gi-Hyeon , Kim Chul-Hwan
Published: February 2018

With the recent developments in power electronics technologies, increased deployment of distributed energy resources (DER) with DC output type at distribution voltage levels and significant increase in the number of sensitive AC and DC loads integrated in distribution network have enforced the traditional power network in the continuous renovation process. In this paper, the load flow solution of hybrid AC/DC distribution networks with the multi-terminal configuration is studied. The impact of voltage source converter (VSC) losses and AC and DC line losses in the presence of DER in the distribution system are assessed. The motivation of this analysis is to consider an increase in the number of converter stations which might result in non-negligible converter losses and the presence of various DER within the network imposing different network scenarios. The proposed schemes are simulated on two modified IEEE 33 bus hybrid AC/DC distribution network test system equipped with VSC-MTDC and the results are presented. Obtained results show that by considering the network losses and the converter losses with large number of converters within the network could lead to very different load flow solution and power transfer between networks, especially considering the AC or DC bus dominated network.
Hydropower Impacts on Electrical System Production Costs in the Southwest United States
Authors: Bain Dominique , Acker Thomas
Published: February 2018

The Colorado River is an important natural resource for the Southwestern United States. Predicted climate change impacts include increased temperature, decreased rainfall and increased probability of drought in this region. Given the large amount of hydropower on the Colorado River and its importance to the bulk electricity system, this purpose of this study was to quantify the value hydropower in operating the electrical system, and examined changes in hydropower value and electricity costs under different possible future drought conditions and regional generation scenarios. The goal was to better understand how these scenarios affect operating costs of the bulk electrical system, as well as the value of the hydropower produced, and proposed a method for doing so. The calculated value of the hydroelectric power was nearly double the mean locational marginal price in the study area, about $73 to $75 for most scenarios, demonstrating a high value of the hydropower. In general, it was found that reduced water availability increased operating costs, and increased the value of the hydropower. A calculated value factor showed that when less hydroelectric power is available, the hydropower is more valuable. Furthermore, the value factor showed that the value of hydro increases with the addition of solar or the retirement of thermal generating resources.
A Duty Cycle Space Vector Modulation Strategy for a Three-to-Five Phase Direct Matrix Converter
Authors: Wang Rutian , Wang Xue , Liu Chuang , Gao Xiwen
Published: February 2018

The duty cycle space vector (DCSV) modulation strategy is of universal significance, and the method can be utilized for different modulation approaches. In this paper, the vectors of input voltages and currents are equivalently represented by a complex two-dimensional space vector, and the vectors of output voltages and currents are equivalently represented by two two-dimensional space vectors. Then, input–output relationships in both the d1-q1 space and the d3-q3 space are obtained. Because the desired output voltages are only mapped onto a reference voltage space vector in the d1-q1 space, the reference in the d3-q3 space is regarded as zero, in order to reduce harmonics of output voltages to the greatest extent. Then, the duty cycle space vector modulation strategy of the three-to-five phase direct matrix converter (DMC) is deduced. Considering the influence of the zero vector on system performance, the duty cycles are decomposed and recomposed to obtain the space vector pulse width modulation (SVPWM) strategy based on the duty cycle space vector. Finally, the accuracy and feasibility of the theory are verified through experiments.
Impact of Demand Side Response on a Commercial Retail Refrigeration System
Authors: Saleh Ibrahim , Postnikov Andrey , Arsene Corneliu , Zolotas Argyrios , Bingham Chris , Bickerton Ronald , Pearson Simon
Published: February 2018

The UK National Grid has placed increased emphasis on the development of Demand Side Response (DSR) tariff mechanisms to manage load at peak times. Refrigeration systems, along with HVAC, are estimated to consume 14% of the UK’s electricity and could have a significant role for DSR application. However, characterized by relatively low individual electrical loads and massive asset numbers, multiple low power refrigerators need aggregation for inclusion in these tariffs. In this paper, the impact of the Demand Side Response (DSR) control mechanisms on food retailing refrigeration systems is investigated. The experiments are conducted in a test-rig built to resemble a typical small supermarket store. The paper demonstrates how the temperature and pressure profiles of the system, the active power and the drawn current of the compressors are affected following a rapid shut down and subsequent return to normal operation as a response to a DSR event. Moreover, risks and challenges associated with primary and secondary Firm Frequency Response (FFR) mechanisms, where the load is rapidly shed at high speed in response to changes in grid frequency, is considered. For instance, measurements are included that show a significant increase in peak inrush currents of approx. 30% when the system returns to normal operation at the end of a DSR event. Consideration of how high inrush currents after a DSR event can produce voltage fluctuations of the supply and we assess risks to the local power supply system.
Development of Easily Accessible Electricity Consumption Model Using Open Data and GA-SVR
Authors: Wang Seunghyeon , Hae Hyeonyong , Kim Juhyung
Published: February 2018

In many countries, DR (Demand Response) has been developed for which customers are motivated to save electricity by themselves during peak time to prevent grand-scale blackouts. One of the common methods in DR, is CPP (Critical Peak Pricing). Predicting energy consumption is recognized as one of the tool for dealing with CPP. There are a variety of studies in developing the model of energy consumption, which is based on energy simulation, data-driven model or metamodelling. However, it is difficult for general users to use these models due to requirement of various sensing data and expertise. And it also takes long time to simulate the models. These limitations can be an obstacle for achieving CPP’s purpose that encourages general users to manage their energy usage by themselves. As an alternative, this research suggests to use open data and GA (Genetic Algorithm)–SVR (Support Vector Regression). The model is applied to a hospital in Korea and 34,636 data sets (1 year) are collected while 31,756 (11 months) sets are used for training and 2880 sets (1 month) are used for validation. As a result, the performance of proposed model is 14.17% in CV (RMSE), which satisfies the Korea Energy Agency’s and ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) error allowance range of ±30%, and ±20% respectively.
Analysis of Lutein, Zeaxanthin, and Meso-Zeaxanthin in the Organs of Carotenoid-Supplemented Chickens
Authors: Phelan David , Prado-Cabrero Alfonso , Nolan John
Published: February 2018

The macular carotenoids (i.e., lutein (L), zeaxanthin (Z) and meso-zeaxanthin (MZ)) exhibit anti-inflammatory, antioxidant and optical properties that are believed to support human health and function. Studying the accumulation and distribution of these nutrients in tissues and organs, in addition to the eye, is an important step in understanding how these nutrients might support global human function and health (e.g., heart and brain). Chicken is an appropriate animal model with which to study the accumulation of these carotenoids in organs, as the relevant transport molecules and carotenoid binding proteins for L, Z and MZ are present in both humans and chickens. In this experiment, a sample of 3 chickens that were supplemented with L and MZ diacetate (active group) and a sample of 3 chickens that received a standard diet (control group) were analysed. Both groups were analysed for L, Z and MZ concentrations in the brain, eyes, heart, lung, duodenum/pancreas, jejunum/ileum, kidney and breast tissue. L, Z and MZ were identified in all the organs/tissues analysed from the active group. L and Z were identified in all of the organs/tissues analysed from the control group; while, MZ was identified in the eyes of these animals only. The discovery that MZ is accumulated in the tissues and organs of chickens supplemented with this carotenoid is important, given that it is known that a combination of L, Z and MZ exhibits superior antioxidant capacity when compared to any of these carotenoids in isolation.
Transcriptomic Analysis Provides Insights into Grafting Union Development in Pecan (Carya illinoinensis)
Authors: Mo Zhenghai , Feng Gang , Su Wenchuan , Liu Zhuangzhuang , Peng Fangren
Published: February 2018

Pecan (Carya illinoinensis), as a popular nut tree, has been widely planted in China in recent years. Grafting is an important technique for its cultivation. For a successful grafting, graft union development generally involves the formation of callus and vascular bundles at the graft union. To explore the molecular mechanism of graft union development, we applied high throughput RNA sequencing to investigate the transcriptomic profiles of graft union at four timepoints (0 days, 8 days, 15 days, and 30 days) during the pecan grafting process. After de novo assembly, 83,693 unigenes were obtained, and 40,069 of them were annotated. A total of 12,180 differentially expressed genes were identified between by grafting. Genes involved in hormone signaling, cell proliferation, xylem differentiation, cell elongation, secondary cell wall deposition, programmed cell death, and reactive oxygen species (ROS) scavenging showed significant differential expression during the graft union developmental process. In addition, we found that the content of auxin, cytokinin, and gibberellin were accumulated at the graft unions during the grafting process. These results will aid in our understanding of successful grafting in the future.
A Non-Extensive Statistical Mechanics View on Easter Island Seamounts Volume Distribution
Authors: Vallianatos Filippos
Published: February 2018

In the volcanic complex processes, inherent long-range interactions exist suggesting that Non-Extensive Statistical mechanics could be used to describe fundamental properties of the system. Based on the non-extensive Tsallis entropy a frequency-volume distribution function is suggested for the Easter Island-Salas y Gomez seamounts chain. Our results demonstrate the applicability of fundamental principles of Tsallis entropy to derive the cumulative distribution of seamounts volumes. The work suggests that the processes responsible for hotspot seamount formation are complex and the cumulative frequency-volume distribution of seamounts in the Easter Island/Salas y Gomez Chain (ESC) are well-described by a q-exponential function. The analysis leads to a non-extensive index q = 1.54 in agreement with that presented in other geodynamic or laboratory scale effects.