bluuebunny/crossref_metadata_2025 huggingface dataset:
Pengaruh Disiplin terhadap Kinerja Para Medis Ruang Perawatan Bedah pada RSUD Raden Mattaher Jambi
Authors: Azizah Azizah
Published: November 2018

The method used in this research is quantitative descriptive method by using statistical formula to help analyze data obtained from the field. The data in this research is obtained by distributing questionnaires to 43 respondents who become the sample. Then processed using Product Moment correlation formula, and assisted with soft ware computer that is SPSS 24 to know there is a relationship between discipline and performance. The result of the research shows that the test regression equation test have positive direction toward employee performance with significant level is proved tcount 3,893>ttable 2.0195 in other words have close enough relationship with performance. For a correlation calculation of 0.519, this indicates a positive relationship between discipline and performance. Furthermore, the determinant coefficient obtained by 27%, the rest of 73% influenced by other factors outside the study of this study.
MapReduce Algorithm for Location Recommendation by Using Area Skyline Query
Authors: Li Chen , Annisa Annisa , Zaman Asif , Qaosar Mahboob , Ahmed Saleh , Morimoto Yasuhiko
Published: November 2018

Location recommendation is essential for various map-based mobile applications. However, it is not easy to generate location-based recommendations with the changing contexts and locations of mobile users. Skyline operation is one of the most well-established techniques for location-based services. Our previous work proposed a new query method, called “area skyline query”, to select areas in a map. However, it is not efficient for large-scale data. In this paper, we propose a parallel algorithm for processing the area skyline using MapReduce. Intensive experiments on both synthetic and real data confirm that our proposed algorithm is sufficiently efficient for large-scale data.
Bibliometric Analysis of Global Research on Clavulanic Acid
Authors: Ramirez-Malule Howard
Published: November 2018

Clavulanic acid (CA), a potent inhibitor of the β-lactam, ase enzyme, is frequently co-formulated with a broad spectrum of antibiotics to treat infections caused by β-lactamase-producing pathogens. In order to evaluate the impact and the progress of CA studies in the last four decades, a bibliometric analysis of the global scientific production of CA was carried out. A total of 39,758 records in the field of CA were indexed in the Scopus database for a 43-year period of study (1975–2017). The results indicated that CA studies have grown, showing three phases (1975–1999, 2000–2003 and 2004–2017) based on records of publications; the results showed a sigmoidal profile. Medicine was the main subject area for CA studies, whereas biochemistry, genetics and molecular biology were areas of research for CA production by Streptomyces clavuligerus (S. clavuligerus). Nevertheless, chemical engineering (as a subject area) had the highest increase in the percentage of publications related to CA production by S. clavuligerus. The United States, France, the United Kingdom, Spain and Brazil were the leading countries in the scientific production of studies on both CA and CA related to S. clavuligerus. This analysis allowed the identification of the area of knowledge with the highest impact on CA studies, the top researchers and their geographic distribution, and also helped to highlight the existence of antibiotic-resistant bacteria as an emergent area in CA research.
The Role of Peroxiredoxin 6 in Cell Signaling
Authors: Arevalo José A. , Vázquez-Medina José Pablo
Published: November 2018

Peroxiredoxin 6 (Prdx6, 1-cys peroxiredoxin) is a unique member of the peroxiredoxin family that, in contrast to other mammalian peroxiredoxins, lacks a resolving cysteine and uses glutathione and π glutathione S-transferase to complete its catalytic cycle. Prdx6 is also the only peroxiredoxin capable of reducing phospholipid hydroperoxides through its glutathione peroxidase (Gpx) activity. In addition to its peroxidase activity, Prdx6 expresses acidic calcium-independent phospholipase A2 (aiPLA2) and lysophosphatidylcholine acyl transferase (LPCAT) activities in separate catalytic sites. Prdx6 plays crucial roles in lung phospholipid metabolism, lipid peroxidation repair, and inflammatory signaling. Here, we review how the distinct activities of Prdx6 are regulated during physiological and pathological conditions, in addition to the role of Prdx6 in cellular signaling and disease.
Peroxiredoxin 6: The Protector of Male Fertility
Authors: O’Flaherty Cristian
Published: November 2018

The spermatozoon is a terminal cell with the unique purpose of delivering the paternal genome to the oocyte during fertilization. Once spermatozoa enter into the female reproductive tract, they count on only the antioxidant protection that they received during spermatogenesis and epididymal maturation. Peroxiredoxins (PRDXs), particularly PRDX6, are important players in the antioxidant protection and regulation of reactive oxygen species (ROS) levels in spermatozoa. PRDX6, through its peroxidase and calcium-independent phospholipase A2 activities, plays a major role in the regulation of ROS to maintain viability and motility and allow the spermatozoon to achieve fertilizing ability during the complex process of capacitation. The absence of PRDX6 is sufficient to promote abnormal reproductive outcomes in mice that resemble what we observe in infertile men. Indeed, Prdx6−/− spermatozoa display low motility and severe DNA damage, which is translated into reduced ability to fertilize oocytes in vitro or produce a low number of pups compared to wild-type controls. This review focuses on the role of PRDX6 as the primary antioxidant enzyme that protects the spermatozoon from oxidative-stress-associated damages to protect the paternal genome and assure fertility.
Dispersion and Pressure Sensitivity of Carbon Nanofiber-Reinforced Polyurethane Cement
Authors: Yang Nan , Zhang Kexin , Sun Quansheng
Published: November 2018

The sensitivity of carbon nanofiber polyurethane cement (CNFPUC) was evaluated to determine whether the cement can act as an intelligent reinforcement material. The percolation thresholds at different polymer-to-cement ratios were determined through experimentation. Taking a specific carbon nanofiber (CNF) content of the percolation zone, several CNFPUC mixtures with different poly-ash ratios and silica fume contents were made. They were then sampled from the mixture and poured into a hexahedron CNFPUC test block; the coefficient of variation of resistance and the piezoresistive characteristics under axial load were examined and the blocks were examined by scanning electron microscope. The sensitivity of the CNFPUC mixture was evaluated via the resistance variation coefficient of a sample hexahedron. For different CNF dosages, the critical value of the variation coefficient was used to assess the sensitivity characteristic by fitting the conic curve. These findings may provide a novel and simple method for determining the sensitivity of CNFPUC mixtures.
Detection of Defects Using Spatial Variances of Guided-Wave Modes in Testing of Pipes
Authors: Mahal Houman , Yang Kai , Nandi Asoke
Published: November 2018

In the past decade, guided-wave testing has attracted the attention of the non-destructive testing industry for pipeline inspections. This technology enables the long-range assessment of pipelines’ integrity, which significantly reduces the expenditure of testing in terms of cost and time. Guided-wave testing collars consist of several linearly placed arrays of transducers around the circumference of the pipe, which are called rings, and can generate unidirectional axisymmetric elastic waves. The current propagation routine of the device generates a single time-domain signal by doing a phase-delayed summation of each array element. The segments where the energy of the signal is above the local noise region are reported as anomalies by the inspectors. Nonetheless, the main goal of guided-wave inspection is the detection of axisymmetric waves generated by the features within the pipes. In this paper, instead of processing a single signal obtained from the general propagation routine, we propose to process signals that are directly obtained from all of the array elements. We designed an axisymmetric wave detection algorithm, which is validated by laboratory trials on real-pipe data with two defects on different locations with varying cross-sectional area (CSA) sizes of 2% and 3% for the first defect, and 4% and 5% for the second defect. The results enabled the detection of defects with low signal-to-noise ratios (SNR), which were almost buried in the noise level. These results are reported with regard to the three different developed methods with varying excitation frequencies of 30 kHz, 34 kHz, and 37 kHz. The tests demonstrated the advantage of using the information received from all of the elements rather than a single signal.
Stability Criterion for Dynamic Gaits of Quadruped Robot
Authors: Jia Yan , Luo Xiao , Han Baoling , Liang Guanhao , Zhao Jiaheng , Zhao Yuting
Published: November 2018

Dynamic-stability criteria are crucial for robot’s motion planning and balance recovery. Nevertheless, few studies focus on the motion stability of quadruped robots with dynamic gait, none of which have accurately evaluated the robots’ stability. To fill the gaps in this field, this paper presents a new stability criterion for the motion of quadruped robots with dynamic gaits running over irregular terrain. The traditional zero-moment point (ZMP) is improved to analyze the motion on irregular terrain precisely for dynamic gaits. A dynamic-stability criterion and measurement are proposed to determine the stability state of the robot and to evaluate its stability. The simulation results show the limitations of the existing stability criteria for dynamic gaits and indicate that the criterion proposed in this paper can accurately and efficiently evaluate the stability of a quadruped robot using such gaits.
Using the Taguchi-Genetic Algorithm to Improve Lithographic Photoresist Operating Conditions of Touch Panels to Upgrade After-Develop Inspection
Authors: Li Meng-Hua , Wang Shen-Tsu
Published: November 2018

In order to use touch control products more conveniently, a general objective is to develop lighter and smaller touch panels. A touch panel using the one glass solution (OGS) is an important development. The black matrix (BM) in an OGS touch panel is used as a black frame. The photoresist is divided into a positive photoresist and a negative photoresist. The BM photoresist is negative. After coating, exposure, and development in the BM process, after-develop inspection is implemented to check if the appearance is abnormal. It is quite difficult to rework the negative photoresist process. There is still room for improving the BM photoresist process capability Cpk. Thus, in order to reduce the customer complaint rate and enhance stability, the photolithography process is improved to enhance Cpk. Among the BM black negative photoresist forming process conditions of OGS products, the pre-baking time is the most important process control factor. The method set up herein improves the original Cpk = 0.90. This study employs the fast messy genetic algorithm (fmGA) to select the optimum orthogonal array of the Taguchi method, so as to implement the decision process of optimum parameter design. The Cpk of the optimum parameter is 2.12.
Online Monitoring Based on Temperature Field Features and Prediction Model for Selective Laser Sintering Process
Authors: Chen Zhehan , Zong Xianhui , Shi Jing , Zhang Xiaohua
Published: November 2018

Selective laser sintering (SLS) is an additive manufacturing technology that can work with a variety of metal materials, and has been widely employed in many applications. The establishment of a data correlation model through the analysis of temperature field images is a recognized research method to realize the monitoring and quality control of the SLS process. In this paper, the key features of the temperature field in the process are extracted from three levels, and the mathematical model and data structure of the key features are constructed. Feature extraction, dimensional reduction, and parameter optimization are realized based on principal component analysis (PCA) and support vector machine (SVM), and the prediction model is built and optimized. Finally, the feasibility of the proposed algorithms and model is verified by experiments.
The Effect of TiC Additive on Mechanical and Electrical Properties of Al2O3 Ceramic
Authors: Grigoriev Sergey , Volosova Marina , Peretyagin Pavel , Seleznev Anton , Okunkova Anna , Smirnov Anton
Published: November 2018

In this study the influence of TiC content on the mechanical and electrical properties of Al2O3-TiC composites containing 30 and 40 vol.% TiC were investigated. The Vickers hardness and fracture toughness of the composites increased with the addition of TiC phase. The composite with 40 vol.% TiC showed the highest flexural strength (687 ± 39 MPa), fracture toughness (7.8 ± 0.4 MPa·m1/2) and hardness (22.3 ± 0.3 GPa) with a homogeneous distribution of the second phase within the ceramic matrix. Besides enhanced mechanical properties, it was found that ceramic composites with more than 30 vol.% TiC fabricated by the spark plasma sintering possess sufficient electrical conductivity for electrical discharge machining as well. Therefore, they do not limit the flexibility of the shape, and any intricate parts can be easily made with these composites which can be recommended for the production of cutting inserts in the tools for machining of superhard hardened steels, hard-to-machine materials, composites and other materials used in mechanical engineering.
Time-Domain Hydro-Elastic Analysis of a SFT (Submerged Floating Tunnel) with Mooring Lines under Extreme Wave and Seismic Excitations
Authors: Jin Chungkuk , Kim Moo-Hyun
Published: November 2018

Global dynamic analysis of a 700-m-long SFT section considered in the South Sea of Korea is carried out for survival random wave and seismic excitations. To solve the tunnel-mooring coupled hydro-elastic responses, in-house time-domain-simulation computer program is developed. The hydro-elastic equation of motion for the tunnel and mooring is based on rod-theory-based finite element formulation with Galerkin method with fully coupled full matrix. The dummy-connection-mass method is devised to conveniently connect objects and mooring lines with linear and rotational springs. Hydrodynamic forces on a submerged floating tunnel (SFT) are evaluated by the modified Morison equation for a moving object so that the hydrodynamic forces by wave or seismic excitations can be computed at its instantaneous positions at every time step. In the case of seabed earthquake, both the dynamic effect transferred through mooring lines and the seawater-fluctuation-induced seaquake effect are considered. For validation purposes, the hydro-elastic analysis results by the developed numerical simulation code is compared with those by a commercial program, OrcaFlex, which shows excellent agreement between them. For the given design condition, extreme storm waves cause higher hydro-elastic responses and mooring tensions than those of the severe seismic case.
Circulating Tumor and Invasive Cell Gene Expression Profile Predicts Treatment Response and Survival in Pancreatic Adenocarcinoma
Authors: Yu Kenneth H. , Ricigliano Mark , McCarthy Brian , Chou Joanne F. , Capanu Marinela , Cooper Brandon , Bartlett Andrew , Covington Christina , Lowery Maeve A. , O’Reilly Eileen M.
Published: November 2018

Previous studies have shown that pharmacogenomic modeling of circulating tumor and invasive cells (CTICs) can predict response of pancreatic ductal adenocarcinoma (PDAC) to combination chemotherapy, predominantly 5-fluorouracil-based. We hypothesized that a similar approach could be developed to predict treatment response to standard frontline gemcitabine with nab-paclitaxel (G/nab-P) chemotherapy. Gene expression profiles for responsiveness to G/nab-P were determined in cell lines and a test set of patient samples. A prospective clinical trial was conducted, enrolling 37 patients with advanced PDAC who received G/nab-P. Peripheral blood was collected prior to treatment, after two months of treatment, and at progression. The CTICs were isolated based on a phenotype of collagen invasion. The RNA was isolated, cDNA synthesized, and qPCR gene expression analyzed. Patients were most closely matched to one of three chemotherapy response templates. Circulating tumor and invasive cells’ SMAD4 expression was measured serially. The CTICs were reliably isolated and profiled from peripheral blood prior to and during chemotherapy treatment. Individual patients could be matched to distinct response templates predicting differential responses to G/nab-P treatment. Progression free survival was significantly correlated to response prediction and ΔSMAD4 was significantly associated with disease progression. These findings support phenotypic profiling and ΔSMAD4 of CTICs as promising clinical tools for choosing effective therapy in advanced PDAC, and for anticipating disease progression.
Production of a Biosurfactant by Cunninghamella echinulata Using Renewable Substrates and Its Applications in Enhanced Oil Spill Recovery
Authors: De Souza Patrícia Mendes , Andrade Silva Nadielly R. , Souza Daniele G. , Lima e Silva Thayse A. , Freitas-Silva Marta C. , Andrade Rosileide F. S. , Silva Grayce K. B. , Albuquerque Clarissa D. C. , Messias Arminda Saconi , Campos-Takaki Galba M.
Published: November 2018

This study aimed to evaluate the production of a surfactant by Cunninghamella echinulata, using agro-industrial residues, corn steep liquor (CSL), and soybean oil waste (SOW). The study had a factorial design, using as a variable response to the reduction of surface tension. C. echinulata was able to produce biosurfactant in assay, CSL (8.82%) and SOW (2%). The results showed that the biosurfactant was successfully produced by C. echinulata and had attractive properties, such as a low surface tension (31.7 mN/m), a yield of 5.18 g/L at 120 h of cultivation, and an anionic profile. It also achieved a reduction in surface tension stability in a wide range of pH values, temperatures, and salinity values. The biosurfactant produced by C. echinulata showed an absence of toxicity to Artemia salina. The influence of the biosurfactant on the viscosity of engine oil, burnt engine oil, diesel, soybean oil post-frying, canola oil, and water was investigated. The results reveal a mechanism for the decrease of the viscosity using hydrophobic substrates and the new biosurfactant solution at 1.5% of the (CMC). This enables the formulation of a low-cost culture medium alternative, based on corn steep liquor and the reuse of soybean oil after frying to produce a biosurfactant. Additionally, performance of the biosurfactant isolated from C. echinulata showed an excellent ability to remove spilled oil, such as diesel (98.7%) and kerosene (92.3%) from marine sand.
Optical Detection of Protrusive Defects on a Thin-Film Transistor
Authors: Tzu Fu-Ming , Chen Jung-Shun , Chou Jung-Hua
Published: November 2018

Protrusive defects on the color filter of thin-film transistor (TFT) liquid crystal displays (LCDs) frequently damage the valuable photomask. A fast method using side-view illuminations with digital charge-coupled devices (CCDs) that filter out ultraviolet (UV)490 nm was developed to detect the protrusive defects of thin-film type in four substrates of the black matrix (BM), red, green, and blue color filters. Between the photomask and substrate, the depth of field (DOF) is normally 300 μm for the proximity-type aligner; we select the four substrates to evaluate the detectability in the task. The experiment is capable of detecting measurements of 300 μm, and measurements even lower than 100 μm can be assessed successfully. The maximum error of the measurement is within 6% among the four samples. Furthermore, the uncertainty analysis of three standard deviations is conducted. Thus, the method is cost-effective to prevent damage for valuable photomasks in the flat-panel display industry.
R-curve Evaluation of Copper and Nickel Single Crystals Using Atomistic Simulations
Authors: Zhuo Xiao Ru , Kim Jang Hyun , Beom Hyeon Gyu
Published: November 2018

The technique of molecular statics (MS) simulation was employed to determine the crack growth resistance curve of Cu and Ni single crystals. Copper and Ni single crystal nanoplates with an edge crack subjected to a tensile displacement were simulated. Stress-displacement curves and snapshots of the atomic configuration corresponding to different displacement levels were presented to elucidate the deformation mechanism. It was observed that the edge crack propagated step by step in a brittle manner, and the amount of crack growth at each step was half the lattice parameter. Through an energy consideration, the critical strain energy release rate at the onset of crack propagation and the crack growth resistance were calculated. The crack growth resistance is larger than the critical strain energy release rate because of the crack growth effect.
About the Reliability of CALPHAD Predictions in Multicomponent Systems
Authors: Gorsse Stéphane , Senkov Oleg
Published: November 2018

This study examines one of the limitations of CALPHAD databases when applied to high entropy alloys and complex concentrated alloys. We estimate the level of the thermodynamic description, which is still sufficient to correctly predict thermodynamic properties of quaternary alloy systems, by comparing the results of CALPHAD calculations where quaternary phase space is extrapolated from binary descriptions to those resulting from complete binary and ternary interaction descriptions. Our analysis has shown that the thermodynamic properties of a quaternary alloy can be correctly predicted by direct extrapolation from the respective fully assessed binary systems (i.e., without ternary descriptions) only when (i) the binary miscibility gaps are not present, (ii) binary intermetallic phases are not present or present in a few quantities (i.e., when the system has low density of phase boundaries), and (iii) ternary intermetallic phases are not present. Because the locations of the phase boundaries and possibility of formation of ternary phases are not known when evaluating novel composition space, a higher credibility database is still preferable, while the calculations using lower credibility databases may be questionable and require additional experimental verification. We estimate the level of the thermodynamic description which would be still sufficient to correctly predict thermodynamic properties of quaternary alloy systems. The main factors affecting the accuracy of the thermodynamic predictions in quaternary alloys are identified by comparing the results of CALPHAD calculations where quaternary phase space is extrapolated from binary descriptions to those resulting from ternary system descriptions.
Lattice Distortion and Phase Stability of Pd-Doped NiCoFeCr Solid-Solution Alloys
Authors: Zhang Fuxiang , Tong Yang , Jin Ke , Bei Hongbin , Weber William J. , Zhang Yanwen
Published: November 2018

In the present study, we have revealed that (NiCoFeCr)100−xPdx (x= 1, 3, 5, 20 atom%) high-entropy alloys (HEAs) have both local- and long-range lattice distortions by utilizing X-ray total scattering, X-ray diffraction, and extended X-ray absorption fine structure methods. The local lattice distortion determined by the lattice constant difference between the local and average structures was found to be proportional to the Pd content. A small amount of Pd-doping (1 atom%) yields long-range lattice distortion, which is demonstrated by a larger (200) lattice plane spacing than the expected value from an average structure, however, the degree of long-range lattice distortion is not sensitive to the Pd concentration. The structural stability of these distorted HEAs under high-pressure was also examined. The experimental results indicate that doping with a small amount of Pd significantly enhances the stability of the fcc phase by increasing the fcc-to-hcp transformation pressure from ~13.0 GPa in NiCoFeCr to 20–26 GPa in the Pd-doped HEAs and NiCoFeCrPd maintains its fcc lattice up to 74 GPa, the maximum pressure that the current experiments have reached.
A Novel Image Encryption Scheme Based on Collatz Conjecture
Authors: Ballesteros Dora M. , Peña Jimmy , Renza Diego
Published: November 2018

Image encryption methods aim to protect content privacy. Typically, they encompass scrambling and diffusion. Every pixel of the image is permuted (scrambling) and its value is transformed according to a key (diffusion). Although several methods have been proposed in the literature, some of them have been cryptanalyzed. In this paper, we present a novel method that deviates the traditional schemes. We use variable length codes based on Collatz conjecture for transforming the content of the image into non-intelligible audio; therefore, scrambling and diffusion processes are performed simultaneously in a non-linear way. With our method, different ciphered audio is obtained every time, and it depends exclusively on the selected key (the size of the key space equal to 8 . 57 × 10 506 ). Several tests were performed in order to analyze randomness of the ciphered audio signals and the sensitivity of the key. Firstly, it was found that entropy and the level of disorder of ciphered audio signals are very close to the maximum value of randomness. Secondly, fractal behavior was detected into scatter plots of adjacent samples, altering completely the behavior of natural images. Finally, if the key was slightly modified, the image could not be recovered. With the above results, it was concluded that our method is very useful in image privacy protection applications.
Wide-Angle Beam Scanning Leaky-Wave Antenna Using Spoof Surface Plasmon Polaritons Structure
Authors: Liu Leilei , Wang Jian , Yin Xiaoxing , Chen Zhi Ning
Published: November 2018

This paper proposes a wide-angle beam scanning leaky-wave antenna (LWA) fed by a novel spoof surface plasmon polaritons (SSPP) transmission line (TL). In the proposed LWA, circular metallic patches are periodically loaded on both sides of the SSPP TL alternately, and convert guided waves into radiating waves. The transmission characteristics of the proposed SSPP TL are analyzed, and the transmission characteristics and radiation patterns of the proposed LWA are simulated and measured. The simulated and measured results show that the proposed LWA provides approximately 12.5 dBi of radiation gain within a frequency range of 8–24 GHz, and a beam scanning range of 90° from forward to backward continuously by increasing the feeding frequency. The proposed LWA, based on a novel SSPP TL, has advantages of single-layer conductor, continuous wide-angle beam scanning, and high gain especially at the broadside direction, which are difficult realize using conventional LWAs.
A Heuristics-Based Policy to Reduce the Curtailment of Solar-Power Generation Empowered by Energy-Storage Systems
Authors: Basmadjian Robert , De Meer Hermann
Published: November 2018

Renewable energy sources, on one hand, are environmentally friendly, but on the other, they suffer from volatility in power generation, which endangers power-grid stability. A viable solution to circumvent the intermittent behavior of renewables is the usage of energy-storage systems. In this paper, we study the energy management of a proof-of-concept system consisting of solar panels, energy-storage systems, a power grid, and household loads. Using neural networks, we identify the most relevant parameters impacting the power generation of solar panels, and then train the corresponding network to derive forecasts. We also go one step further, and propose a heuristics-based energy-management policy for the purpose of reducing curtailments. We show that our proposed policy outperforms the naive policy by 8%, which does not consider any power-generation forecasts.
A Hybrid Non-Convex Compressed Sensing Approach for Array Diagnosis Using Sparse Promoting Norm with Perturbation Technique
Authors: Li Wei , Deng Weibo , Yang Qiang , Migliore M.D.
Published: November 2018

The use of ℓ p ( 0 < p < 1 ) norm minimization will improve array diagnosis performance provided that the issue of local minima associated to its non-convex nature is properly handled. In order to overcome this deficiency, a hybrid method using random perturbation and non-convex optimization is investigated in this paper. Although it acquires a higher computational time, the trade-off between an accurate diagnosis and the computational burden appears to be acceptable. Theoretical analysis and simulation results demonstrate that the proposed method overcomes this disadvantage effectively and achieves better performance compared to the standard ℓ 1 norm minimization with a smaller number of far-field measurements, suggesting that the proposed method can be used to improve the performance of array diagnosis.
A New Study on the Temperature and Bias Dependence of the Kink Effects in S22 and h21 for the GaN HEMT Technology
Authors: Crupi Giovanni , Raffo Antonio , Vadalà Valeria , Vannini Giorgio , Caddemi Alina
Published: November 2018

The aim of this feature article is to provide a deep insight into the origin of the kink effects affecting the output reflection coefficient (S22) and the short-circuit current-gain (h21) of solid-state electronic devices. To gain a clear and comprehensive understanding of how these anomalous phenomena impact device performance, the kink effects in S22 and h21 are thoroughly analyzed over a broad range of bias and temperature conditions. The analysis is accomplished using high-frequency scattering (S-) parameters measured on a gallium-nitride (GaN) high electron-mobility transistor (HEMT). The experiments show that the kink effects might become more or less severe depending on the bias and temperature conditions. By using a GaN HEMT equivalent-circuit model, the experimental results are analyzed and interpreted in terms of the circuit elements to investigate the origin of the kink effects and their dependence on the operating condition. This empirical analysis provides valuable information, simply achievable by conventional instrumentation, that can be used not only by GaN foundries to optimize the technology processes and, as a consequence, device performance, but also by designers that need to face out with the pronounced kink effects of this amazing technology.
Demodulation of Angular Position and Velocity from Resolver Signals via Chebyshev Filter-Based Type III Phase Locked Loop
Authors: Liu Huan , Wu Zhong
Published: November 2018

A high-accuracy demodulation algorithm is required to estimate angular position and angular velocity from resolver signals. In order to improve the estimation accuracy of conventional phase-locked loop (PLL) based demodulation method, a Chebyshev filter-based type III PLL method is proposed in this paper. The proposed method makes PLL become a system of type III tracking loop, which could greatly reduce the theoretical constant deviation in the estimation results of conventional type II PLL in case of variable speed. Meanwhile, the eigenvalues of type III PLL are placed to be the same position as those of a Chebyshev low-pass filter. In this way, demodulation parameters with stronger filter properties can be obtained to effectively suppress the high-frequency measurement noise in resolver signals. Thus, the proposed method can achieve higher demodulation precision compared with the conventional ones. Simulations and experiments are performed to validate the proposed demodulation method.
An Advanced Maximum Power Point Tracking Method for Photovoltaic Systems by Using Variable Universe Fuzzy Logic Control Considering Temperature Variability
Authors: Wang Yiwang , Yang Yong , Fang Gang , Zhang Bo , Wen Huiqing , Tang Houjun , Fu Li , Chen Xiaogao
Published: November 2018

In this study maximum power point tracking (MPPT) is applied to the photovoltaic (PV) system to harvest the maximum power output. The output power of the PV effect changes according to external solar irradiation and ambient temperature conditions. In the existing MPPT strategies, most of them only take variations in radiation level into account, rarely considering the impact of temperature changes. However, the temperature coefficients (TC) play an important role in the PV system, especially in applications where ambient temperature changes are relatively large. In this paper, an MPPT method is presented for a PV system that considers the temperature change by using variable universe fuzzy logic control (VUFLC). By considering the ambient temperature change in PV modules, the proposed control method can regulate the contraction and expansion factor of VUFLC, which eliminates the influence of temperature variability and improves the performance of MPPT, therefore achieving fast and accurate tracking control. The proposed method was evaluated for a PV module under different ambient conditions and its control performance is compared with other MPPT strategies by simulation and experimental results.
Energy Efficiency Analysis of Multi-Type Floating Bodies for a Novel Heaving Point Absorber with Application to Low-Power Unmanned Ocean Device
Authors: Cong Dongsheng , Shang Jianzhong , Luo Zirong , Sun Chongfei , Wu Wei
Published: November 2018

Long-term energy supplies hinder the application of the low-power unmanned ocean devices to the deep sea. Ocean wave energy is a renewable resource with amount stores of enormous and high density. The wave energy converter (WEC) could be miniaturized so that it can be integrated into the devices to make up the power module. In this paper, a small novel heaving point absorber of energy supply for low-power unmanned ocean devices is developed based on the counter-rotating self-adaptive mechanism. The floating body as an important part of the heaving point absorber, the geometric parameters is optimized to increase the efficiency of power production. Through constructing the constitutive relation between the geometric parameters, the wave force, the motion displacement, the motion velocity, and the capture width ratio of the floating body, the energy efficiency characteristics of the multi-type floating bodies are calculated, and the optimal shape is selected. On the other hand, in the calculation process of the wave force, the Froude-Krylov method is an effective method to accurately calculate the wave excitation force. Meanwhile, nonlinear static and dynamic Froude-Krylov force effectively overcomes the inaccuracy of the linear models and reduces the time consumed to simulate. Finally, the wave force, heaving velocity, heaving displacement, and capture width ratio of the three floating bodies are compared and analyzed, and the results show that the cylindrical floater that is vertically placed on the wave surface is more suitable for the novel heaving wave energy point absorber.
Techno-Economic Analysis of Rural 4th Generation Biomass District Heating
Authors: Soltero Víctor , Chacartegui Ricardo , Ortiz Carlos , Quirosa Gonzalo
Published: November 2018

Biomass heating networks provide renewable heat using low carbon energy sources. They can be powerful tools for economy decarbonization. Heating networks can increase heating efficiency in districts and small size municipalities, using more efficient thermal generation technologies, with higher efficiencies and with more efficient emissions abatement technologies. This paper analyzes the application of a biomass fourth generation district heating, 4GDH (4th Generation Biomass District Heating), in a rural municipality. The heating network is designed to supply 77 residential buildings and eight public buildings, to replace the current individual diesel boilers and electrical heating systems. The development of the new fourth district heating generation implies the challenge of combining using low or very low temperatures in the distribution network pipes and delivery temperatures in existing facilities buildings. In this work biomass district heating designs based on third and fourth generation district heating network criteria are evaluated in terms of design conditions, operating ranges, effect of variable temperature operation, energy efficiency and investment and operating costs. The Internal Rate of Return of the different options ranges from 6.55% for a design based on the third generation network to 7.46% for a design based on the fourth generation network, with a 25 years investment horizon. The results and analyses of this work show the interest and challenges for the next low temperature DH generation for the rural area under analysis.
OBS Data Analysis to Quantify Gas Hydrate and Free Gas in the South Shetland Margin (Antarctica)
Authors: Song Sha , Tinivella Umberta , Giustiniani Michela , Singhroha Sunny , Bünz Stefan , Cassiani Giorgio
Published: November 2018

The presence of a gas hydrate reservoir and free gas layer along the South Shetland margin (offshore Antarctic Peninsula) has been well documented in recent years. In order to better characterize gas hydrate reservoirs, with a particular focus on the quantification of gas hydrate and free gas and the petrophysical properties of the subsurface, we performed travel time inversion of ocean-bottom seismometer data in order to obtain detailed P- and S-wave velocity estimates of the sediments. The P-wave velocity field is determined by the inversion of P-wave refractions and reflections, while the S-wave velocity field is obtained from converted-wave reflections received on the horizontal components of ocean-bottom seismometer data. The resulting velocity fields are used to estimate gas hydrate and free gas concentrations using a modified Biot-Geertsma-Smit theory. The results show that hydrate concentration ranges from 10% to 15% of total volume and free gas concentration is approximately 0.3% to 0.8% of total volume. The comparison of Poisson’s ratio with previous studies in this area indicates that the gas hydrate reservoir shows no significant regional variations.
Stabilization of High-Organic-Content Water Treatment Sludge by Pyrolysis
Authors: Lee Ye-Eun , Kim I-Tae , Yoo Yeong-Seok
Published: November 2018

Water treatment sludge from algal blooms were analyzed and compared with general water treatment sludge as the pyrolysis temperature was varied from 300 °C to 900° C. Elemental analysis showed that the water treatment sludge in the eutrophication region has ~12% carbon content, higher than that (8.75%) of general water treatment sludge. X-ray diffraction (XRD) analysis of both types of sludge showed that amorphous silica changed to quartz and weak crystalline structures like kaolinite or montmorillonite were decomposed and changed into stronger crystalline forms like albite. Fourier transform infrared spectroscopy (FT-IR) peaks of humic/fulvic acid that indicated the affinity to combine with heavy metals disappeared above 700 °C. Toxicity characteristic leaching procedure (TCLP), conducted to determine the heavy metal leaching amount of pyrolyzed water treatment sludge, showed the lowest value of 5.7 mg/kg at 500 °C when the humic acid was not decomposed. At 500 °C, the heavy metal leaching ratio to the heavy metal content of high organic content water treatment sludge and low organic content water treatment sludge were 1.87% and 3.19%, respectively, and the water treatment sludge of higher organic content was more stable. In other words, pyrolysis of water treatment sludge with high organic content at 500 °C increases the inorganic matter crystallinity and heavy metal leaching stability.
Effects of the Second-Stage of Rotor with Single Abnormal Blade Angle on Rotating Stall of a Two-Stage Variable Pitch Axial Fan
Authors: Zhang Lei , Zhang Liang , Zhang Qian , Jiang Kuan , Tie Yuan , Wang Songling
Published: November 2018

It is of great value to study the impact of abnormal blade installation angle on the inducement mechanism of rotating stall to achieve the active control of rotating stall in an axial fan. Based on throttle value function and SST k-ω turbulence model, numerical simulations of the unsteady flow process in stall condition of an axial flow fan with adjustable vanes were carried out, and the influence mechanism of abnormal stagger angle of a single blade in the second stage rotor on induced position and type of stall inception and evolution process of rotating stall were analyzed. The results show that compared with synchronous adjustment of blade angle, the blade with abnormal stagger angle will cause the increase of flow rate at the beginning of stall and make the fan fall into an unstable condition in advance. The existence of blade with abnormal angle does not cause the change of the induced position and type of stall inception and the inducement mechanism of rotating stall, which are the same as the axial fan with normal blade angle. Moreover, the single blade with abnormal deviation angle has important impacts on the 3D unsteady evolution process from stall inception to stall cell formation in two rotors.
Application of UAV Photogrammetric System for Monitoring Ancient Tree Communities in Beijing
Authors: Qiu Zixuan , Feng Zhong-Ke , Wang Mingming , Li Zhenru , Lu Chao
Published: November 2018

Ancient tree community surveys have great scientific value to the study of biological resources, plant distribution, environmental change, genetic characteristics of species, and historical and cultural heritage. The largest ancient pear tree communities in China, which are rare, are located in the Daxing District of Beijing. However, the environmental conditions are tough, and the distribution is relatively dispersed. Therefore, a low-cost, high-efficiency, and high-precision measuring system is urgently needed to complete the survey of ancient tree communities. By unmanned aerial vehicle (UAV) photogrammetric program research, ancient tree information extraction method research, and ancient tree diameter at breast height (DBH) and age prediction model research, the proposed method can realize the measurement of tree height, crown width, and prediction of DBH and tree age with low cost, high efficiency, and high precision. Through experiments and analysis, the root mean square error (RMSE) of the tree height measurement was 0.1814 m, the RMSE of the crown width measurement was 0.3292 m, the RMSE of the DBH prediction was 3.0039 cm, and the RMSE of the tree age prediction was 4.3753 years, which could meet the needs of ancient tree survey of the Daxing District Gardening and Greening Bureau. Therefore, a UAV photogrammetric measurement system proved to be capable when applied in the survey of ancient tree communities and even in partial forest inventories.
Fat Replacers in Baked Food Products
Authors: Colla Kathryn , Costanzo Andrew , Gamlath Shirani
Published: November 2018

Fat provides important sensory properties to baked food products, such as colour, taste, texture and odour, all of which contribute to overall consumer acceptance. Baked food products, such as crackers, cakes and biscuits, typically contain high amounts of fat. However, there is increasing demand for healthy snack foods with reduced fat content. In order to maintain consumer acceptance whilst simultaneously reducing the total fat content, fat replacers have been employed. There are a number of fat replacers that have been investigated in baked food products, ranging from complex carbohydrates, gums and gels, whole food matrices, and combinations thereof. Fat replacers each have different properties that affect the quality of a food product. In this review, we summarise the literature on the effect of fat replacers on the quality of baked food products. The ideal fat replacers for different types of low-fat baked products were a combination of polydextrose and guar gum in biscuits at 70% fat replacement (FR), oleogels in cake at 100% FR, and inulin in crackers at 75% FR. The use of oatrim (100% FR), bean puree (75% FR) or green pea puree (75% FR) as fat replacers in biscuits were equally successful.
Assessment of the Impact of Deformable Registration of Diagnostic MRI to Planning CT on GTV Delineation for Radiotherapy for Oropharyngeal Carcinoma in Routine Clinical Practice
Authors: Taylor Alice , Sen Mehmet , Prestwich Robin J. D.
Published: November 2018

Background: Aim of study was to assess impact of deformable registration of diagnostic MRI to planning CT upon gross tumour volume (GTV) delineation of oropharyngeal carcinoma in routine practice. Methods: 22 consecutive patients with oropharyngeal squamous cell carcinoma treated with definitive (chemo)radiotherapy between 2015 and 2016, for whom primary GTV delineation had been performed by a single radiation oncologist using deformable registration of diagnostic MRI to planning CT, were identified. Separate GTVs were delineated as part of routine clinical practice (all diagnostic imaging available side-by-side for each delineation) using: CT (GTVCT), MRI (GTVMR), and CT and MRI (GTVCTMR). Volumetric and positional metric analyses were undertaken using contour comparison metrics (Dice conformity index, centre of gravity distance, mean distance to conformity). Results: Median GTV volumes were 13.7 cm3 (range 3.5–41.7), 15.9 cm3 (range 1.6–38.3), 19.9 cm3 (range 5.5–44.5) for GTVCT, GTVMR and GTVCTMR respectively. There was no significant difference in GTVCT and GTVMR volumes; GTVCTMR was found to be significantly larger than both GTVMR and GTVCT. Based on positional metrics, GTVCT and GTVMR were the least similar (mean Dice similarity coefficient (DSC) 0.71, 0.84, 0.82 for GTVCT–GTVMR, GTVCTMR–GTVCT and GTVCTMR–GTVMR respectively). Conclusions: These data suggest a complementary role of MRI to CT to reduce the risk of geographical misses, although they highlight the potential for larger target volumes and hence toxicity.
Healthy Lifestyle: Relationship between Mediterranean Diet, Body Composition and Physical Fitness in 13 to 16-Years Old Icelandic Students
Authors: Galan-Lopez Pablo , Ries Francis , Gisladottir Thordis , Domínguez Raúl , Sánchez-Oliver Antonio J.
Published: November 2018

Childhood and adolescent obesity are currently among the greatest challenges for public health. Physical activity, physical fitness, and adherence to the Mediterranean diet (MD), representing powerful indicators of healthy lifestyles, are shown as determinant factors in the prevention and treatment of obesity. The aim of the present study has been to analyse the relationship between health-related physical fitness components, body composition, and adherence to MD in 387 Icelandic adolescents of 13–16-years old (54% boys). The ALPHA Fitness Test was used to measure physical fitness and body composition. The KIDMED questionnaire was used to assess the adherence to MD among participants. Associations between variables were tested according to gender and age using linear regression models and analysis of variance. Participants with high/medium adherence to MD showed significantly higher endurance scores in both the boys and the girls. Gender differences were found. The boys in high/medium MD categories had significantly lower fat percentages and ran a 4 × 10 m sprint faster than the girls. The girls scored higher than the boys in endurance and speed-agility tests. It can be concluded that a high and medium adherence to MD is associated with high and very high endurance in both the girls and the boys.