bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of gravitational waves during preheating in the Starobinsky inflationary model
Authors: Jin Guoqiang , Fu Chengjie , Wu Puxun , Yu Hongwei
Published: June 2020

The production of GWs during preheating in the Starobinsky model with a nonminimally coupled auxiliary scalar field is studied through the lattice simulation in this paper. We find that the GW spectrum $$\Omega _{\mathrm{gw}}$$Ωgw grows fast with the increase of the absolute value of coupling parameter $$\xi $$ξ. This is because the resonant bands become broad with the increase of $$|\xi |$$|ξ|. When $$\xi <0$$ξ<0, $$\Omega _{\mathrm{gw}}$$Ωgw begins to grow once the inflation ends and grows faster than the case of $$\xi >0$$ξ>0. $$\Omega _{\mathrm{gw}}$$Ωgw reaches the maximum at $$\xi =-20$$ξ=-20 ($$\xi =42$$ξ=42 for the case $$\xi >0$$ξ>0) and then decreases with slight oscillation. Furthermore we find that the GWs produced in the era of preheating satisfy the limits from the Planck and next-generation CMB experiments.
A critical overview of stationary solar models based on polytropic gases
Authors: Marasco Addolorata , Romano Antonio
Published: June 2020

We critically analyze the models of a main-sequence star based on polytropic gases. First, we put in evidence that the hypothesis of polytropic gas is compatible with the constitutive equation of an ideal gas if the transformations inside the star are adiabatic. Then, neither the mono- or the polyphasic models of an ideal gas can be applied inside the stellar core for the existence in this region of nuclear reactions. Moreover, we prove that polyphasic models doesn’t allow the existence of C1solutions of the stationary hydrodynamic equations.
The Dynamics of Binary Neutron Star Mergers and GW170817
Authors: Radice David , Bernuzzi Sebastiano , Perego Albino
Published: June 2020

With the first observation of a binary neutron star merger through gravitational waves and light, GW170817, compact binary mergers have now taken the center stage in nuclear astrophysics. They are thought to be one of the main astrophysical sites of production of r-process elements, and merger observations have become a fundamental tool to constrain the properties of matter. Here, we review our current understanding of the dynamics of neutron star mergers in general and of GW170817 in particular. We discuss the physical processes governing the inspiral, merger, and postmerger evolution, and we highlight the connections between these processes, the dynamics, and the multimessenger observables. Finally, we discuss open questions and issues in the field and the need to address them through a combination of better theoretical models and new observations.
Real-Time AFM and Impedance Corrosion Monitoring of Environmentally Friendly Ceria Films on AA7075
Authors: Stevanović Sanja I. , Lekka Maria , Lanzutti Alex , Tasić Nikola , Živković Ljiljana S. , Fedrizzi Lorenzo , Bajat Jelena B.
Published: June 2020

Cerium-based conversion coatings have emerged as promising green alternatives to the harmful chromium-based ones, but the mechanism of corrosive protection still remains a subject of academic and industrial research. This study focuses at small scale phenomena of corrosion inhibition imparted by ceria (CeO2) to AA7075. Ceria nanoparticles were deposited from diluted and concentrated CeO2 sols by immersion. A multi-analytical approach, combining Atomic Force microscopy (AFM), Scanning Kelvin Probe Force Microscopy, Glow Discharge Optical Emission Spectroscopy, open circuit potential and electrochemical impedance spectroscopy was employed. Deposition of ceria films led to deactivation of cathodic sites, i.e. decreased Volta potential difference, resulting in increased corrosion inhibition. In situ AFM real-time monitoring revealed that during exposure to NaCl electrolyte, the changes in size of deposited ceria aggregates occurred: nanoparticles disintegrated/desorbed and re-deposited at the coating surface. The process was found to be dynamic in nature. Small particles size and inherent reactivity are believed to accelerate this phenomenon. Due to the greater CeO2 reservoir, this phenomenon was more pronounced with a thicker film, imparting longer term protection.
A primer on tissue pH and local anesthetic potency
Authors: Pope Rebecca L. E. , Brown Angus M.
Published: June 2020

The relationship between pH, p Ka, and degree of local anesthetic ionization is quantified by the Henderson-Hasselbalch equation. As presented in standard textbooks, the effect of pH on the degree of ionization of any particular local anesthetic is not immediately clear due to the x-axis displaying pH − p Ka, which requires conversion to pH, based on the p Ka for each local anesthetic, a complex process. We present a graphical solution that clarifies the interrelationships between pH, p Ka, and degree of ionization by plotting p Ka on the x-axis versus the percentage of unionized local anesthetic on the y-axis. The vertical intercept from the x-axis to the pH curves allows rapid and accurate estimation of the degree of ionization of any local anesthetic of known p Ka.
Knowledge gains in a professional development workshop on diversity, equity, inclusion, and implicit bias in academia
Authors: Harrison-Bernard Lisa M. , Augustus-Wallace Allison C. , Souza-Smith Flavia M. , Tsien Fern , Casey Gregory P. , Gunaldo Tina P.
Published: June 2020

As literature indicates, historic racism and implicit bias throughout academia have been profound metrics leading to a lack of diversity, as related to people from underrepresented groups according to race and ethnicity, among biomedical sciences graduate students in U.S. universities. Recognizing such challenges, a team of biomedical scientists and inclusivity educators developed and implemented a pilot training program within an academic health sciences center as an initial step to educate faculty and staff regarding their roles in the promotion of an inclusive academic environment, receptive to all students, including underrepresented students. The 3-h workshop included didactic modules, videos, teaching modules, and active attendee participation. Faculty and staff were presented common terminology and ways to promote the development of an inclusive and diverse academic workforce. Compared with pre-workshop, post-workshop survey results indicated a statistically significant improvement in attendee knowledge of correctly identifying definitions of “implicit bias,” “status leveling,” “color-blind racial attitudes,” “tokenism,” and “failure to differentiate.” Additionally, by the end of the workshop, participants had a statistically significant increase in self-perceptions regarding the importance of improving diversity and recognizing biases and stereotypes in graduate education, knowing what to say when interacting with people from different cultures, and the ability to acknowledge bias when mentoring students from groups underrepresented in the biomedical field. This preliminary initiative was successful in the introduction of faculty and staff to the importance of fostering an inclusive academic environment and thereby developing a diverse workforce.
Two-Weight, Weak-Type Norm Inequalities for Fractional Integral Operators and Commutators on Weighted Morrey and Amalgam Spaces
Authors: Wang Hua
Published: June 2020

Let 0<γ<n and Iγ be the fractional integral operator of order γ, Iγfx=∫ℝnx−yγ−nfydy and let b,Iγ be the linear commutator generated by a symbol function b and Iγ, b,Iγfx=bx⋅Iγfx−Iγbfx. This paper is concerned with two-weight, weak-type norm estimates for such operators on the weighted Morrey and amalgam spaces. Based on weak-type norm inequalities on weighted Lebesgue spaces and certain Ap-type conditions on pairs of weights, we can establish the weak-type norm inequalities for fractional integral operator Iγ as well as the corresponding commutator in the framework of weighted Morrey and amalgam spaces. Furthermore, some estimates for the extreme case are also obtained on these weighted spaces.
Anti-NMDAR-Positive Small-Cell Lung Cancer Paraneoplastic Limbic Encephalitis: A Case Report and Literature Review
Authors: Sohal Raman , Adams Steven H. , Phogat Vishal , Harish Abha , Lopez Carlos Ynigo D. , Williams Michael P. A. , Khurana Kamal K. , Abuzuaiter Basel , Jagroop Nia , Narapureddy Bhavya
Published: June 2020

Introduction. Paraneoplastic limbic encephalitis (PLE) is a rare disease that presents as rapid onset dementia characterized by short-term memory loss (STM), anxiety, and behavioral changes. Anti-NMDAR antibodies are unfrequently reported in PLE associated with small-cell lung cancer (SCLC). Given that PLE can precede the diagnosis of cancer, it is very important that once infectious, metabolic, nutritional, or structural disorders associated with short-term memory loss are ruled out that vigorous effort must be made to rule out underlying malignancy. Case. We report a rare case of PLE as the presenting symptom of SCLC. A 72-year-old male with history of COPD was brought to the ED by his wife after he was found to have short-term memory loss, including forgetfulness of his wedding anniversary the day before, and anxiety. Neurological exam showed impaired short-term recall on MOCA. CT head showed no evidence of infarct. Lumbar puncture was performed which showed lymphocytic pleocytosis, a nonspecific inflammatory change. CSF panel was negative for HSV, Neisseria, Hemophilus, E. coli, and HIV. Initial EEG was unremarkable, though a repeat EEG showed mild slowing of the posterior dominant rhythm consistent with mild encephalopathy. MRI showed equivocal increased FLAIR on T2-weighted images in the bilateral temporal lobes, left greater than right. CTA thorax showed bulky mediastinal and right hilar LAD. FNA of the R4 lymph node revealed SCLC. The NM bone scan showed no osteoblastic lesions. While the serum autoantibody panel was positive for anti-NMDAR, the CSF autoantibody panel returned entirely negative. Chemotherapy with etoposide and cisplatin was started on Day 4 of admission. The patient’s neurological symptoms showed improvement following chemotherapy. Conclusion. This case highlights the importance of recognizing short-term memory loss as a feature of PLE.
Iris Vascular Malformation with 360-Degree Iridocorneal Angle Affectation
Authors: Calleja-García Cristina , Suárez-Baraza Jorge , Mencía-Gutiérrez Enrique
Published: June 2020

Vascular iris lesions are rare and can sometimes be associated to systemic vascular lesions. They usually cause spontaneous recurrent hyphema. The differential diagnosis should be considered primarily with iris rubeosis and with highly vascular tumors as iris melanoma. Generally, vascular lesions of hemangioma type are located in the iris without extension to iridocorneal angle. We present a case of a 77-year-old male with an iris vascular lesion suggestive of racemose hemangioma, who is asymptomatic, and with 360-degree iridocorneal angle affectation showing no lesions at any other location.
A Session-Based Song Recommendation Approach Involving User Characterization along the Play Power-Law Distribution
Authors: Sánchez-Moreno Diego , López Batista Vivian F. , Muñoz Vicente M. Dolores , Gil González Ana B. , Moreno-García María N.
Published: June 2020

In recent years, streaming music platforms have become very popular mainly due to the huge number of songs these systems make available to users. This enormous availability means that recommendation mechanisms that help users to select the music they like need to be incorporated. However, developing reliable recommender systems in the music field involves dealing with many problems, some of which are generic and widely studied in the literature while others are specific to this application domain and are therefore less well-known. This work is focused on two important issues that have not received much attention: managing gray-sheep users and obtaining implicit ratings. The first one is usually addressed by resorting to content information that is often difficult to obtain. The other drawback is related to the sparsity problem that arises when there are obstacles to gather explicit ratings. In this work, the referred shortcomings are addressed by means of a recommendation approach based on the users’ streaming sessions. The method is aimed at managing the well-known power-law probability distribution representing the listening behavior of users. This proposal improves the recommendation reliability of collaborative filtering methods while reducing the complexity of the procedures used so far to deal with the gray-sheep problem.
Movie Review Summarization Using Supervised Learning and Graph-Based Ranking Algorithm
Authors: Khan Atif , Gul Muhammad Adnan , Zareei Mahdi , Biswal R. R. , Zeb Asim , Naeem Muhammad , Saeed Yousaf , Salim Naomie
Published: June 2020

With the growing information on web, online movie review is becoming a significant information resource for Internet users. However, online users post thousands of movie reviews on daily basis and it is hard for them to manually summarize the reviews. Movie review mining and summarization is one of the challenging tasks in natural language processing. Therefore, an automatic approach is desirable to summarize the lengthy movie reviews, and it will allow users to quickly recognize the positive and negative aspects of a movie. This study employs a feature extraction technique called bag of words (BoW) to extract features from movie reviews and represent the reviews as a vector space model or feature vector. The next phase uses Naïve Bayes machine learning algorithm to classify the movie reviews (represented as feature vector) into positive and negative. Next, an undirected weighted graph is constructed from the pairwise semantic similarities between classified review sentences in such a way that the graph nodes represent review sentences, while the edges of graph indicate semantic similarity weight. The weighted graph-based ranking algorithm (WGRA) is applied to compute the rank score for each review sentence in the graph. Finally, the top ranked sentences (graph nodes) are chosen based on highest rank scores to produce the extractive summary. Experimental results reveal that the proposed approach is superior to other state-of-the-art approaches.
Large Data Technology-Based Analysis Method of Sudden Eco-Environmental Toxic Pollution
Authors: He Guilan , Yao Junping
Published: June 2020

Sudden environmental toxic pollution accidents occur from time to time at home and abroad, seriously affecting the safety of the ecological environment. Different environmental factors affect the use of manual inspection and analysis methods, causing inaccurate results of inspection and analysis. In view of this problem, a large data technology-based analysis of sudden ecological environmental toxic pollution is proposed. Method. The genome and proteome in different environments were analyzed, and the target organisms were strictly defined to determine the effect of the molecular toxicity of pollution factors on the ecological environment. According to the molecular toxicity, the sudden eco-environmental toxicity pollution was analyzed using large data technology. Under the action of different particle sizes, dosages, and adsorption times of activated carbon, the experiments confirmed that the results of large data technology analysis are more accurate, which have provided necessary means for the protection of the ecological environment.
Blood Pressure during Blood Collection and the Implication for Absolute Cardiovascular Risk Assessment
Authors: Chapman Niamh , Picone Dean S , Climie Rachel E. , Schultz Martin G. , Nelson Mark R. , Sharman James E.
Published: June 2020

Background: Blood collection and blood pressure (BP) measurements are routinely performed during the same consultation to assess absolute cardiovascular disease (CVD) risk. This study aimed to determine the effect of blood collection on BP and subsequent calculation of the absolute CVD risk. Methods: Forty-five participants aged 58 ± 9 years (53% male) had systolic BP (SBP) measured using clinical guideline methods (clinic SBP). Then, on a separate visit, BP was measured immediately before, during, and after blood collection. Absolute CVD risk scores were calculated (Framingham equation) using SBP from each measurement condition and compared. Results: The prevalence of low (<10%), moderate (10–15%), and high (≥15%) absolute CVD risks among the participants was 67%, 22%, and 11%, respectively, using clinic SBP. SBP values before and during blood collection were significantly higher compared to values after blood collection (130 ± 18 and 132 ± 19 vs. 126 ± 18 mm Hg; p = 0.010 and p = 0.003, respectively). However, there were no significant differences between clinic SBP (128 ± 18 mm Hg) and blood collection SBP (p = 0.99) or the absolute CVD risk scores (7.3 ± 6.5; 7.6 ± 5.9; 7.7 ± 6.1; and 7.1 ± 5.7%, respectively; p = 0.995 for all). The mean intraclass correlation (95% CI) indicated good agreement between absolute CVD risk scores calculated with clinic SBP and each blood collection SBP (0.86 [95% CI 0.74–0.92], 0.85 [95% CI 0.71–0.91], and 0.87 [95% CI 0.76–0.93], respectively; p < 0.001, for all). Conclusion: Absolute CVD risk calculation is not affected by use of SBP measurements recorded at the time of blood collection. Therefore, it is acceptable to collect blood and measure BP during the same consultation for absolute CVD risk assessment.
Factors Influencing Electrode Position and Bending of the Proximal Lead in Deep Brain Stimulation for Movement Disorders
Authors: Niederer Jacob , Patriat Rémi , Rosenberg Oren , Palnitkar Tara , Darrow David , Park Michael C. , Schrock Lauren , Eberly Lynn E. , Harel Noam
Published: June 2020

Background: The introduction of intracranial air (ICA) during deep brain stimulation (DBS) surgery is thought to have a negative influence on targeting and clinical outcomes. Objective: To investigate ICA volumes following surgery and other patient-specific factors as potential variables influencing translocation of the DBS electrode and proximal lead bowing. Methods: High-resolution postoperative computed tomography scans (≤1.0 mm resolution in all directions) within 24 h following DBS surgery and 4–6 weeks of follow-up were acquired. A total of 50 DBS leads in 33 patients were available for analysis. DBS leads included Abbott/St. Jude Medical InfinityTM, Boston Scientific VerciseTM, and Medtronic 3389TM. Results: Both ICA volume and anatomical target were significantly associated with measures of DBS electrode translocation. ICA volume and DBS lead model were found to be significant predictors of proximal lead bowing. Measures of proximal lead bowing and translocation along the electrode trajectory for the Medtronic 3389TM DBS lead were significantly larger than measures for the Abbott/St. Jude Medical InfinityTM and Boston Scientific VerciseTM DBS leads. Conclusion: The association between ICA volume and translocation of the DBS electrode is small in magnitude and not clinically relevant for DBS cases within a normal range of postoperative subdural air volumes. Differences in proximal lead bowing observed between DBS leads may reflect hardware engineering subtleties in the construction of DBS lead models.
Two Cases of Giant Melanocytoma (Hyperpigmented Magnocellular Nevus)
Authors: Sia David I.T. , Agi Jorge , Grewal Parampal , Russell Laurie , Weis Ezekiel
Published: June 2020

Melanocytoma or hyperpigmented magnocellular nevus is a variant of melanocytic nevus that is most commonly seen in the optic nerve, but has also been reported to occur in the iris, ciliary body, choroid, sclera, and conjunctiva. We present two cases of giant uveal melanocytoma with histopathology. The first case occurred in a 10-year-old girl who presented with decreased vision in the right eye and a mushroom-shaped pigmented choroidal lesion measuring 15.5 mm in apical height. The lesion was abutting the lens but not causing a cataract. This was diagnosed as a choroidal melanocytoma on open scleral window biopsy. The second case was in a 68-year-old lady, referred for a left nasal pigmented choroidal lesion measuring 8 mm in apical height and having a mushroom configuration. The lesion grew to 8.6 mm in height and was complicated by a vitreous hemorrhage and rhegmatogenous retinal detachment and was treated with iodine-125 plaque brachytherapy. Subsequently, the treated eye became a painful phthisical eye and was enucleated. Histopathology confirmed melanocytoma with extrascleral extension but without malignant transformation. Features of melanocytoma and other very large cases reported in the literature are discussed.
Associations between Proton Pump Inhibitor and Histamine-2 Receptor Antagonist and Bone Mineral Density among Kidney Transplant Recipients
Authors: Lyu Beini , Hansen Karen E. , Jorgenson Margaret R. , Astor Brad C.
Published: June 2020

Background: In the general population, use of proton pump inhibitor (PPI) has been linked to higher risk of osteoporotic fractures. PPI is commonly prescribed in kidney transplant recipients (KTRs). However, the effect of PPI on osteoporosis in KTRs is largely unstudied. Methods: A total of 1,774 adult KTRs in the Wisconsin Allograft Recipient Database with at least one eligible bone mineral density (BMD) measurement at least 3 months after transplantation were included in the analyses. Associations between use of PPI and histamine-2 receptor antagonist (H2RA) at 3 months after transplantation and subsequent slope of T-score were assessed. Results: A total of 1,478 (83.3%) participants were using a PPI at 3 months after transplantation. Compared to the use of H2RA, use of PPI was not significantly associated with annualized slope of hip T-score (β = –0.0039, 95% CI –0.00497 to 0.0021) or annualized slope of spine T-score (β = –0.017, 95% CI –0.049 to 0.083) after adjustment for potential confounders. Similarly, no significant association between use of PPI and slope of T-score was observed when defining PPI/H2RA exposure as use within 6 months of the initial BMD measurement, or only including participants with at least 2 BMD measurements, or stratified by different age and sex. Conclusions: Use of PPI was not associated with an increased rate of BMD loss in KTRs. Our results support previous findings that PPI use does not have a significant effect on bone mineral loss.
Comparison of Prodromal Symptoms of Patients with Behavioral Variant Frontotemporal Dementia and Alzheimer Disease
Authors: Korhonen Titta , Katisko Kasper , Cajanus Antti , Hartikainen Päivi , Koivisto Anne M. , Haapasalo Annakaisa , Remes Anne M. , Solje Eino
Published: June 2020

Introduction: Behavioral variant frontotemporal dementia (bvFTD) is the most common clinical subtype of frontotemporal lobar degeneration. bvFTD is often characterized by changes in behavior and personality, frequently leading to psychiatric misdiagnoses. On the other hand, substantial clinical overlap with other neurodegenerative diseases, such as Alzheimer disease (AD), further complicates the diagnostics. Objective: Our aim was to identify the main differences in early symptoms of bvFTD and AD in the prodromal stages of the diseases. In addition, patients with bvFTD were analyzed separately according to whether they carry the C9orf72repeat expansion or not. Methods: Patient records of bvFTD (n = 75) and AD (n = 83) patients were analyzed retrospectively for memory and neuropsychiatric symptoms, sleeping disorders, and somatic complaints before the setting of the accurate diagnosis. Results: A total of 84% of bvFTD patients (n = 63) and 98.8% of AD patients (n = 82) reported subjective memory disturbances in the prodromal phases of the disease. bvFTD patients presented significantly more often with sleeping disorders, headache, inexplicable collapses, transient loss of consciousness, somatization, delusions, and hallucinations, suicidality, changes in oral behaviors, and urinary problems. In addition, poor financial judgement was frequently detected in patients with prodromal bvFTD. Aberrant sensations in the nose and throat without any physical explanation, regarded as somatizations, emerged only in bvFTD patients with the C9orf72 repeat expansion. Conclusions: Subjective reporting of impaired episodic memory is a poor indicator in differentiating bvFTD from AD. Sleeping disturbances, delusions, hallucinations, and unexplained somatic complaints in a patient with cognitive disturbances should prompt the clinicians to consider bvFTD as a possible diagnostic option behind these symptoms. The spectrum of symptoms in the prodromal stages of bvFTD may be more diverse than the latest criteria suggest.
Cytogenetic Characterization of a Small Evolutionary Rearrangement Involving Chromosomes BTA21 and OAR18
Authors: De Lorenzi Lisa , Pauciullo Alfredo , Iannuzzi Alessandra , Parma Pietro
Published: June 2020

Both cattle (Bos taurus) and sheep (Ovis aries) belong to the Bovidae family but to different subfamilies, Bovinae and Caprinae, respectively. From a chromosomal point of view, apart from the already known centric fusions (that occurred during the evolutionary process in the Bovidae family) and the small differences in the chromosome classification, the 2 karyotypes are very similar in banding patterns. In this study, the combination of bioinformatics techniques and physical mapping of DNA markers enabled the identification of a micro-rearrangement, a small inversion involving bovine chromosome 21 (BTA21) and the corresponding sheep chromosome 18 (OAR18). The aim of this study was the cytogenetic characterization of this difference in genomic assemblies between cattle and sheep in this single chromosome region. To verify the inversion in FISH experiments, we used the BACs 442H08 and 222H03 from the INRA library and BACs 134H22 and 436P08 from the sheep-specific CHORI library. The results confirmed the presence of the inverted fragment in sheep compared to the cattle genome. Genomic rearrangements may have consequences depending on their influence on gene activity, but in this case no gene or transcribed DNA portion seemed to be involved. In conclusion, we showed for the first time, concerning autosomes, that besides the already known centric fusions also other differences exist between the bovine and sheep karyotypes. Furthermore, we demonstrated that the combination of a bioinformatics approach and physical mapping is a valid tool for the identification of currently unknown rearrangements between related species.
Different Levels of Chromatin Condensation in Partamona chapadicola and Partamona nhambiquara (Hymenoptera, Apidae)
Authors: Lopes Denilce M. , Travenzoli Natália M. , Fernandes Anderson , Campos Lucio A.O.
Published: June 2020

Studies in several organisms have contributed to the understanding of heterochromatin and its biological importance. In bees of the tribe Meliponini, the presence of chromosomes with totally heterochromatic arms has been attributed to the mechanism of karyotype evolution in which this group accumulated heterochromatin to maintain telomere stability after centric fission events. In the present study, the use of classical and molecular cytogenetic techniques as well as automated image analysis software for the description of the karyotypes of Partamonachapadicola and P. nhambiquara bee species revealed variability in the compaction and patterns of chromatin structure. Although both species have the same chromosome number as other species in the genus Partamona (2n = 34), C-banding and image analyses indicated the existence of chromosomes with 3 regions of different staining intensities, suggesting a chromatin structure with distinct patterns and characteristics. Repetitive DNA probes hybridized only in the euchromatic regions, whereas the regions with intermediate staining intensity did not show any hybridization signals. This suggests that these regions present features more similar to heterochromatin. Evidence of the existence of a chromatin class with intermediate condensation compared to euchromatin and heterochromatin indicates a potential mechanism for heterochromatin amplification and demonstrates the need for further studies on this topic. This previously unrecognized class of chromatin should be taken into account in the study of all Meliponini chromosomes.
Theoretical approach model of building integrated photovoltaic thermal air collector
Authors: Fudholi Ahmad , Zohri Muhammad , Taslim Ivan , Indrianti Merita Ayu , Manyoe Intan Noviantari
Published: June 2020

Over recent years the photovoltaic technology has obtained signiﬁcant development, especially in building integrated photovoltaic thermal (BIPVT) system. Photovoltaic thermal (PVT) air collectors are advantageous because of their efficiency. Various studies have been conducted to determine the ideal parameters of PVT air collectors. Few theoretical approach models of PVT air collector systems were used to help detect occurrences in a PVT collector system and calculate the optimal parameters. The heat transfer and energy balance of PVT air collectors were analysed and reviewed based on the model, quantity of cover, channels and forms of the collector. A mathematical model was developed to describe actual working situations and to examine new shut PVT collectors. The first law of thermodynamics is the principal equation in the model. Different analysis methods were utilised to evaluate PVT performances, which are generally based on energy and exergy analyses. This review focuses on theoretical approach model of single-pass PVT air collector.
Optimal parameter estimation for a DC motor using genetic algorithm
Authors: Amiri Mohammad Soleimani , Ibrahim Mohd Faisal , Ramli Rizauddin
Published: June 2020

Estimating the parameters of a geared DC motor is crucial in terms of its non-linear features. In this paper, parameters of a geared DC motor are estimated genetically. Mathematical model of the DC motor is determined by Kirchhoff’s law and dynamic model of its shafts and gearbox. Parameters of the geared DC motor are initially estimated by MATLAB/SIMULINK. The estimated parameters are defined as initial values for Genetic Algorithm (GA) to minimize the error of the simulated and actual angular trajectory captured by an encoder. The optimal estimated model of the geared DC motor is validated by different voltages as the input of the actual DC motor and its mathematical model. The results and numerical analysis illustrate it can be ascertained that GA is appropriate to estimate the parameters of platforms with non linear characteristics.
Comparison between proposed fuzzy logic and ANFIS for MPPT control for photovoltaic system
Authors: Farah Lotfi , Haddouche Adel , Haddouche Ali
Published: June 2020

In this paper, a maximum power point tracking (MPPT) algorithm for photovoltaic (PV) systems is achieved based on fuzzy logic controller (FLC) and compared with an anfis (neuro-fuzzy) based mppt controller, this method allies the abilities of artificial neural networks in learning and the power of fuzzy logic to handle imprecise data. Both methods are simulated using matlab/ simulink. The choise of power variation and the current variation as inputs of the proposed controllersreducesthe calculation. Both FLC and ANFIS based MPPTare tested in terms of steady state performance and the pv system dynamic.
Simulink model of transformer differential protection using phase angle difference based algorithm
Authors: Iqteit Nassim A. , Yahya Khalid
Published: June 2020

An application of phase-angle-difference based algorithm with percentage differential relays is presented in this paper. In the situation where the transformer differential relay is under magnetizing inrush current, the algorithm will be utilized to block the process. In this study, the technique is modeled and implemented using Simulink integrated with MATLAB. The real circuit model of power transformer and current transformers are considered in the simulation model. The results confirmed the effectiveness of the technique in different operation modes; such as, magnetizing inrush currents, current transformers saturation and internal transformer faults.
Ca[Mg3SiN4]Ce3+ phosphor: effect of particle concentration on lighting properties of the 7000K IPW-LEDs
Authors: Vu Q. S. , Dao Tang Tin , Tran Minh
Published: June 2020

Nowadays, the white-light-emitting diodes (LEDs) have a vast application on the real-life based on its superior advantages such as energy efficiency, long lifetime, compactness, and environment-friendly and designable features in comparison with incandescent and fluorescent lamps. In this paper, we co-doping the Ca[Mg3SiN4]Ce3+ Phosphor on the phosphor compound of the 7000K In-cup Packaging White LEDs (IPW-LEDs) for improving the lighting properties. By varying the concentration of Ca[Mg3SiN4]Ce3+ Phosphor from 0% to 1.8%, the effect of the Ca[Mg3SiN4]Ce3+ Phosphor on the D-CCT, CRI, CQS, and LO of the 7000K IPW-LEDs are investigated. Using the Light Tool and software, the research results show that the concentration of the IPW-LEDs has a massive influence on the lighting properties of the 7000K IPW-LEDs. All the results are convinced by Light Tool simulation.
Loss minimization DTC electric motor drive system based on adaptive ANN strategy
Authors: Yi Sim Sy , Utomo Wahyu Mulyo , Hwang Goh Hui , Kai Chien Siong , Siang Alvin John Lim Meng , Zambri Nor Aira , Buswig Yonis M. Y. , Law Kah Haw , Yi Sim Gia
Published: June 2020

Electric motor drive systems (EMDS) have been recognized as one of the most promising motor systems recently due to their low energy consumption and reduced emissions. With only some exceptions, EMDS are the main source for the provision of mechanical energy in industry and accounts for about 60% of global industrial electricity consumption. Large energy efficiency potentials have been identified in EMDS with very short payback time and high-cost effectiveness. Typical, during operation at rated mode, the motor drive able to hold its good efficiencies. However, a motor usually operates out from rated mode in many applications, especially while under light load, it reduced the motor’s efficiency severely. Hence, it is necessary that a conventional drive system to embed with loss minimization strategy to optimize the drive system efficiency over all operation range. Conventionally, the flux value is keeping constantly over the range of operation, where it should be highlighted that for any operating point, the losses could be minimize with the proper adjustment of the flux level to a suitable value at that point. Hence, with the intention to generate an adaptive flux level corresponding to any operating point, especially at light load condition, an online learning Artificial Neural Network (ANN) controller was proposed in this study, to minimize the system losses. The entire proposed strategic drive system would be verified under the MATLAB/Simulink software environment. It is expected that with the proposed online learning Artificial Neural Network controller efficiency optimization algorithm can achieve better energy saving compared with traditional blended strategies.
Advanced control scheme of a unifiedpower flow controller using sliding mode control
Authors: Hinda Abdellatif , Khiat Mounir , Boudjema Zinelaabidine
Published: June 2020

This paper presents an advanced control scheme based on sliding mode control of a unified power flow controller (UPFC). This controller can generate a number of benefits in terms of static and dynamic operation of the power system such as the control law is synthesized with two kinds of controllers: sliding mode controller (SMC), and proportional integral (PI). Their respective performances are compared in terms of reference monitoring, sensitivity to disturbances and robustness. We have to study the problem of controlling power in electric system by UPFC. The simulation results show the effectiveness of the proposed strategy especially in chattering-free behavior, response to sudden load variations and robustness. All the simulations for the above work have been carried out using MATLAB/Simulink. Various simulations have given very satisfactory results and we have successfully improved the active and reactive power flows on a line of transmission, as well as to control voltage at the bus where it is connected, the studies and illustrate the effectiveness and capability of UPFC in improving power.
Optimal distribution of power under stress on power grid in real-time by reactive compensation-management and development in balance
Authors: A. Tadjeddine Ali , I. Arbaoui , H. Hamiani , A. Chaker
Published: June 2020

The industrial development, lifestyle and modernization of the management sectors in Algeria have led to an increase in demand for electricity power in recent years and an increase in demand for the energy sector. This high demand for power has led to problems with voltage drops, particularly as regards the quality of this voltage during periods peak load. Thanks to research on the development of the electricity transmission system in the South-West region of Algeria and based on the theoretical results. We have obtained an optimal solution for the location of the regulation systems for voltage and the frequency in the substations that exhibit strong violations and periodic static destabilization, in particular, the stations at the end of the 220Kv transmission lines. The techniques of modeling and controlling the voltage per frequency (Hz/V) as well as the critical analysis variants have been studied and confirmed using advanced real-time numerical simulation.
A new multilevel DC-AC converter topology with reduced switch using multicarrier sinusoidal pulse width modulation
Authors: Palanisamy R. , Vidyasagar S. , Kalyanasundaram V. , Karthikeyan D. , Selvakumar K. , Selvabharathi D. , Vijayakumar K.
Published: June 2020

Multilevel converters have a significant role in power processing control in the power system, which has some inherent features like reduced harmonics, high power & medium voltage, reduced voltage stress. In this proposed paper, a novel multilevel inverter with reduced number of switches and without passive components. The proposed inverter generates 15 level output voltage with suitable switching pulse generation using multicarrier sinusoidal pulse width modulation (MSPWM) and different level of voltages are obtained with variation of modulation index. Also coupled inductor is used to minimize the harmonic content and smoothing output current. The scheme which includes different range of unequal voltage sources. As a result, the proposed system it reduces switching control complexity and there is no voltage balancing problem. This paper elucidates the operating modes, voltage stress minimisation and harmonic reduction are discussed. The results of the proposed multilevel dc-ac converter are verified using matlab/simulink. The simulation & hardware results of the proposed inverter were verified using matlab simulink and dsPIC controller respectively, which was analysed with different voltage level and different modulation index.
Development of multiple plug-in electric vehicle mobile charging station using bidirectional converter
Authors: Savio A. Dominic , A. Vimala Juliet
Published: June 2020

Electric vehicle (EV) charging station powered by the scattered energy sources with DC Nanogrid (NG) provides an option for uninterrupted charging. The NG powered by the renewable energy sources (RES) of photovoltaic (PV) and wind energy. When the excess power produced by the renewable energy stored in the local energy storage unit (ESU) utilized during shortage power from the renewable sources. During the overloading of NG and demand of energy in ESU; the mobile charging station (MCS) provides an uninterrupted charging. The MCS provides an option for battery swapping and vehicle to grid feasibility. The MCS required to monitor the state of charge (SOC) and state of health (SOH) of the battery. Monitoring of SOC and SOH related to the various battery parameters like voltage, current and temperature. A laboratory prototype is developed and tested the practical possibility of EV to NG and Internet of things (IoT) based monitoring of battery parameters.
Application of direct MRAC in PI controller for DC-DC boost converter
Authors: Ardhenta Lunde , Subroto Ramadhani Kurniawan
Published: June 2020

Almost all electronic components require a DC power supply at present days. The needs of DC power supplies from low voltage scales, medium voltages such as generators, to high voltage scales for high voltage electricity transmission. The improvement of PI controller performances is presented in this paper. The adaptation gains improve transient response of DC-DC Boost Converter several operating conditions. Massachusetts Institute of Technology (MIT) rule is applied as an adaptive mechanism to determine the optimal control parameters in some conditions. The used adaptive control technique is Direct Model Reference Adaptive Control (MRAC), this method as able to control system in some various input voltage. The proposed method has a stable response and able to reach the model reference smoothly. However, the response of the system has instantaneously overshoot and follows the response back of model reference. The responses of proposed controller have short period of rise time, settling time, and overshoot.
Design and implement of pulse width modulation with low-cost hardware in the loop
Authors: Azze Qasim Al , Ali Mohammed Hasan
Published: June 2020

The paper presents a low-cost hardware in the loop based on Arduino. Sinusoidal Pulse Width Modulation (SPWM) designing, analyzing, and implementation is experimented as hardware in the loop. Sinusoidal Pulse Width Modulation implementation via MATLAB\Simulation demonstrates in this work. In this paper, Arduino Mega2560 platform, microcontroller, introduce as hardware. A comparative study of the both techniques is presented. Arduino interfaces with PC Target MATLAB environment. Three phases Voltage Source Inverter directs by the generated pulses that loads with three phases RLC. The obtaining output current and voltage waveform of RLC load of Hardware-in-the-Loop validates to the MATLAB\simulation output waveform. The compering shows the output waveforms are primarily having the same pattern. Arduino consider as the lost cost as microcontroller which could be used in real application.
A novel fast MPPT strategy used for grid-connected residential PV system applied in morocco
Authors: Sahbani Sana , Mahmoudi Hassane , Hasnaoui Abdennebi , Kchikach Mustapha , Benchraa Hanane
Published: June 2020

Regardless its significant potential for generating renewable energy, Moroccan government prohibited the injection of production surplus into the low voltage (LV) network because it still lack the implementing decreases, that represents one of the principal challenges for residential self-production in the country. The focus of this paper work is to introduce and analyze a novel fast MPPT strategy applied in an improved grid-connected Residential PV system respecting the current legislative framework in Morocco, which allow to the consumer being an actor in the energy transition towards a low-carbon society by reducing his dependence to the electrical grid and managing his own energy consumption efficiently by a good switching between photovoltaic (PV) source and the grid and therefore making a framework of smart residence management system. The overall system is designed to improve the energy control performance with two techniques: the first one uses a novel high performance controller to track the maximum power point (MPP) of a photovoltaic array under fast irradiation and load changes. Among the advantages of this proposed controller is the stability of its output voltage with fast response speed to the required parameters. The second one uses a Power Factor Correction (PFC) circuit to ensure the power quality regulation in the grid side via a predictive current control method. Finally, the stability of a closed-loop system is simulated and analyzed using commercial software offering sufficient conditions to validate a practical stability and robustness of the proposed overall designed system.
Application of inductive coupling for wireless power transfer
Authors: Alhamrouni Ibrahim , Iskandar M. , Salem Mohamed , J. Awalin Lilik , Jusoh Awang , Sutikno Tole
Published: June 2020

Considering the massive development that took place in the past two decades, wireless power transfer has yet to show the applicability to be used due to several factors. This work focuses on determining the main parameters like, mutual inductance, and coupling coefﬁcient for a pair of helical coils for wireless power transfer applications. These parameters are important in designing and analyzing a wireless power transfer system based on the phenomenon of inductive/ resonant inductive coupling. Here presents a simple approach based on fundamental laws of physics for determining the coupled coil parameters for single layered helical coils. The results conducted by computer simulation which is MATLAB. Furthermore, this analysis is used to study the effect of change in coil diameter, mutual inductance coefficient and change in distance between coils on parameters like self and mutual inductance of coupled coils which is of great importance in Wireless Power Transfer applications. The research yielded promising results to show that wireless power transfer has huge possibility to solve many existing industrial problems.
Active power filter with hysteresis current control loop using rectifier boost technique
Authors: Baharom Rahimi , Yassin Ihsan Mohd , Hidayat Nabil
Published: June 2020

This paper presents the Hysteresis Current Control (HCC) to improve the power quality of power electronic converters. The development of HCC was implemented using Active Power Filter (APF) function based on rectifier boost technique to control the range of upper and lower bands. Through this technique, the supply current waveform followed the shape of the sinusoidal reference signal, thus, the distorted input current waveform becomes sinusoidal and in the same phase with the input voltage. As a result, the THD level and switching losses can be reduced, thus improving the power factor of the power supply system. In order to verify the proposed operation, validation of the proposed HCC was done through MATLAB. Selected simulation results are presented.
Implementation of SVM for five-level cascaded H-Bridge multilevel inverters utilizing FPGA
Authors: Al jewari Maher Abd Ibrahim , Jidin Auzani , Tarusan Siti Azura Ahmad , Rasheed Mohammed
Published: June 2020

The Space Vector Modulation SVM technique has won large acceptance for AC drive applications. However the utilization of multilevel inverters connected with SVM by Digital signal processor (DSP) raise the intricacy of control algorithm or computational load, increases of the obtaining distortions output voltage. The development of SVM in multilevel inverters may offer higher numbers of switching vectors for acquiring further enhancements of output voltage performances and implement by using Field Programmer Gate Array (FPGA), investigate lower Total Hormonic Distortion (THD). This paper reports the performance evaluation of SVM for five-level of Cascaded H-Bridge Multilevel Inverter CHMI using MATLAB/Simulink, which is sampled at the minimum sampling time, i.e. DT = 5 μs. The switching signals for driving insulated gate bipolar transistor (IGBTs) which are stored in MATLAB workspaces, are then used to be programmed in FPGA using a Quartus II software. Which can be stated the lower THD of the simulation result is about 14.48% for five-level CHMI and experiment result is about 14.31% for five-level CHMI at modulation index M_i=0.9. The error percentage between the simulation results and experimental results of the fundamental output voltage in SVM is small which is approximately less than 1 %.