bluuebunny/crossref_metadata_2025 huggingface dataset:
Upper-Body Control and Mechanism of Humanoids to Compensate for Angular Momentum in the Yaw Direction Based on Human Running
Authors: Otani Takuya , Hashimoto Kenji , Miyamae Shunsuke , Ueta Hiroki , Natsuhara Akira , Sakaguchi Masanori , Kawakami Yasuo , Lim Hum-Ok , Takanishi Atsuo
Published: January 2018

Many extant studies proposed various stabilizing control methods for humanoids during the stance phase while hopping and running. Although these methods contribute to stability during hopping and running, humanoid robots do not swing their legs rapidly during the flight phase to prevent rotation in the yaw direction. Humans utilize their torsos and arms when running to compensate for the angular momentum in the yaw direction generated by leg movement during the flight phase. In this study, we developed an angular momentum control method based on human motion for a humanoid upper body. The method involves calculation of the angular momentum generated by the movement of the humanoid legs and calculation of the torso and arm motions required to compensate for the angular momentum of the legs in the yaw direction. We also developed a humanoid upper-body mechanism having human link length and mass properties, using carbon-fiber-reinforced plastic and a symmetric structure for generating large angular momentum. The humanoid robot developed in this study could generate almost the same angular momentum as that of a human. Furthermore, when suspended in midair, the humanoid robot achieved angular momentum compensation in the yaw direction.
Application of the Wave Propagation Approach to Sandwich Structures: Vibro-Acoustic Properties of Aluminum Honeycomb Materials
Authors: Piana Edoardo , Petrogalli Candida , Paderno Diego , Carlsson Ulf
Published: January 2018

Sandwich structures are manufactured using multiple combinations of materials for core and laminates. The real performances are influenced by variability in the composing layers and even by the uncertainties introduced while bonding them together. Therefore, experimental tests are usually the preferred way to assess the most important parameters required to develop and to characterize the product, the main downsides lying in their cost and time consumption. This work explores a practical application of the wave propagation approach by means of a case study, in which some significant properties of an aluminum honeycomb panel are obtained starting from simple vibro-acoustic tests carried out on beam specimens. After determining the frequency-dependent bending stiffness function, the sound transmission loss is predicted and compared with the experimental results obtained in sound transmission suites. The same vibro-acoustic tests are used to estimate the core shear modulus. Finally, a parametric study is proposed to show how this technique can be effectively used in the early design stage, when producing physical samples is often impossible due to time and money constraints. The method proved to be a reliable and powerful tool in all the tested applications, providing good results with limited computational effort.
Omnidirectional Jump of a Legged Robot Based on the Behavior Mechanism of a Jumping Spider
Authors: Zhu Yaguang , Chen Long , Liu Qiong , Qin Rui , Jin Bo
Published: January 2018

To find a common approach for the development of an efficient system that is able to achieve an omnidirectional jump, a jumping kinematic of a legged robot is proposed based on the behavior mechanism of a jumping spider. To satisfy the diversity of motion forms in robot jumping, a kind of 4 degrees of freedom (4DoFs) mechanical leg is designed. Taking the change of joint angle as inspiration by observing the behavior of the jumping spider during the acceleration phase, a redundant constraint to solve the kinematic is obtained. A series of experiments on three types of jumping—vertical jumping, sideways jumping and forward jumping—is carried out, while the initial attitude and path planning of the robot is studied. The proposed jumping kinematic is verified on the legged robot experimental platform, and the added redundant constraint could be verified as being reasonable. The results indicate that the jumping robot could maintain stability and complete the planned task of jumping, and the proposed spider-inspired jumping strategy could easily achieve an omnidirectional jump, thus enabling the robot to avoid obstacles.
Low-Voltage Ride-Through Control Strategy for a Grid-Connected Energy Storage System
Authors: Bak Yeongsu , Lee June-Seok , Lee Kyo-Beum
Published: January 2018

This paper presents a low-voltage ride-through (LVRT) control strategy for grid-connected energy storage systems (ESSs). In the past, researchers have investigated the LVRT control strategies to apply them to wind power generation (WPG) and solar energy generation (SEG) systems. Regardless of the energy source, the main purpose of the LVRT control strategies is to inject reactive power into the grid depending on the grid-code regulations using the grid-side inverter; the proposed LVRT control strategy for grid-connected ESSs also has the same purpose. However, unlike the WPG and SEG systems having unidirectional power flow, grid-connected ESSs have a bidirectional power flow. Therefore, the charging condition of the grid-connected ESSs should be considered for the LVRT control strategy. The proposed LVRT control strategy for grid-connected ESSs determines the injection quantity of the active and reactive currents, and the strategy depends on the voltage drop ratio of the three-phase grid. Additionally, in this paper, we analyzed the variations of the point of common coupling (PCC) voltage depending on the phase of the reactive current during the charging and discharging conditions. The validity of the proposed LVRT control strategy is verified and the variations of the PCC voltage of the grid-connected ESS are analyzed by simulation and experimental results.
Proton Charge Radius from Electron Scattering
Authors: Sick Ingo
Published: January 2018

The rms-radius R of the proton charge distribution is a fundamental quantity needed for precision physics. This radius, traditionally determined from elastic electron-proton scattering via the slope of the Sachs form factor G e ( q 2 ) extrapolated to momentum transfer q 2 = 0 , shows a large scatter. We discuss the approaches used to analyze the e-p data, partly redo these analyses in order to identify the sources of the discrepancies and explore alternative parameterizations. The problem lies in the model dependence of the parameterized G ( q ) needed for the extrapolation. This shape of G ( q < q m i n ) is closely related to the shape of the charge density ρ ( r ) at large radii r, a quantity that is ignored in most analyses. When using our physics knowledge about this large-r density together with the information contained in the high-q data, the model dependence of the extrapolation is reduced, and different parameterizations of the pre-2010 data yield a consistent value for R = 0.887 ± 0.012 fm. This value disagrees with the more precise value 0.8409 ± 0.0004 fm determined from the Lamb shift in muonic hydrogen.
Programming of Cell Resistance to Genotoxic and Oxidative Stress
Authors: Velegzhaninov Ilya , Ievlev Vitaly , Pylina Yana , Shadrin Dmitry , Vakhrusheva Olesya
Published: January 2018

Different organisms, cell types, and even similar cell lines can dramatically differ in resistance to genotoxic stress. This testifies to the wide opportunities for genetic and epigenetic regulation of stress resistance. These opportunities could be used to increase the effectiveness of cancer therapy, develop new varieties of plants and animals, and search for new pharmacological targets to enhance human radioresistance, which can be used for manned deep space expeditions. Based on the comparison of transcriptomic studies in cancer cells, in this review, we propose that there is a high diversity of genetic mechanisms of development of genotoxic stress resistance. This review focused on possibilities and limitations of the regulation of the resistance of normal cells and whole organisms to genotoxic and oxidative stress by the overexpressing of stress-response genes. Moreover, the existing experimental data on the effect of such overexpression on the resistance of cells and organisms to various genotoxic agents has been analyzed and systematized. We suggest that the recent advances in the development of multiplex and highly customizable gene overexpression technology that utilizes the mutant Cas9 protein and the abundance of available data on gene functions and their signal networks open new opportunities for research in this field.
Non Melanoma Skin Cancer Pathogenesis Overview
Authors: Didona Dario , Paolino Giovanni , Bottoni Ugo , Cantisani Carmen
Published: January 2018

(1) Background: Non-melanoma skin cancer is the most frequently diagnosed cancer in humans. The process of skin carcinogenesis is still not fully understood. However, several studies have been conducted to better explain the mechanisms that lead to malignancy; (2) Methods: We reviewed the more recent literature about the pathogenesis of non-melanoma skin cancer focusing on basal cell carcinomas, squamous cell carcinoma and actinic keratosis; (3) Results: Several papers reported genetic and molecular alterations leading to non-melanoma skin cancer. Plenty of risk factors are involved in non-melanoma skin cancer pathogenesis, including genetic and molecular alterations, immunosuppression, and ultraviolet radiation; (4) Conclusion: Although skin carcinogenesis is still not fully understood, several papers demonstrated that genetic and molecular alterations are involved in this process. In addition, plenty of non-melanoma skin cancer risk factors are now known, allowing for an effective prevention of non-melanoma skin cancer development. Compared to other papers on the same topic, our review focused on molecular and genetic factors and analyzed in detail several factors involved in non-melanoma skin cancer.
Reagent Tracker Dyes Permit Quality Control for Verifying Plating Accuracy in ELISPOT Tests
Authors: Lehmann Alexander , Megyesi Zoltan , Przybyla Anna , Lehmann Paul
Published: January 2018

ELISPOT assays enable the detection of the frequency of antigen-specific T cells in the blood by measuring the secretion of cytokines, or combinations of cytokines, in response to antigenic challenges of a defined population of PBMC. As such, these assays are suited to establish the magnitude and quality of T cell immunity in infectious, allergic, autoimmune and transplant settings, as well as for measurements of anti-tumor immunity. The simplicity, robustness, cost-effectiveness and scalability of ELISPOT renders it suitable for regulated immune monitoring. In response to the regulatory requirements of clinical and pre-clinical immune monitoring trials, tamper-proof audit trails have been introduced to all steps of ELISPOT analysis: from capturing the raw images of assay wells and counting of spots, to all subsequent quality control steps involved in count verification. A major shortcoming of ELISPOT and other related cellular assays is presently the lack of audit trails for the wet laboratory part of the assay, in particular, the assurance that no pipetting errors have occurred during the plating of antigens and cells. Here, we introduce a dye-based reagent tracking platform that fills this gap, thereby increasing the transparency and documentation of ELISPOT test results.
The Effect of Detectable HIV Viral Load among HIV-Infected Children during Antiretroviral Treatment: A Cross-Sectional Study
Authors: Moolasart Visal , Chottanapund Suthat , Ausavapipit Jarurnsook , Likanonsakul Sirirat , Uttayamakul Sumonmal , Changsom Don , Lerdsamran Hatairat , Puthavathana Pilaipan
Published: January 2018

The RNA viral load of human immunodeficiency virus (HIV) is initially used to determine the status of the HIV infection. The goal of therapy following treatment failure is to achieve and maintain virologic suppression. A detectable viral load may relate to the progression of HIV infection. A cross-sectional survey was conducted from January 2013 to December 2014 at the Bamrasnaradura Infectious Diseases Institute, Thailand. The aim was to determine the prevalence of detectable HIV viral load (dVL) and analyze the factors associated with post-dVL conditions that occur independently of a switch to a new antiretroviral agent. The prevalence of dVL was 27% (27 of 101). The mean ages of dVL and non-dVL children were 12.0 and 12.3 years, respectively. Age, sex, body mass index for age z-scores, previous tuberculosis disease history and parental tuberculosis history of both groups were not significantly different (p > 0.05). The prevalence of poor adherence (<95%), influenza-like illness (ILI) and opportunistic infections were higher in dVL than non-dVL children (p < 0.05). The mean nadir CD4 cell count during the study was lower in dVL than non-dVL children (646 compared to 867, respectively; p < 0.05). Other factors were not significant (all p > 0.05). In multivariable analysis, dVL was significantly associated with ILI (odds ratio (OR) = 9.6, 95% confidence interval (CI) = 1.3–69.4), adherence (OR = 0.195, 95% CI = 0.047–0.811) and nadir CD4 during the study (OR = 1.102, 95% CI = 1.100–1.305). The prevalence of dVL was 27% with this dVL among HIV-infected children found to be associated with ILI, poor adherence and lower nadir CD4 during the study.
Factors Associated with Not Breastfeeding and Delaying the Early Initiation of Breastfeeding in Mecca Region, Saudi Arabia
Authors: Azzeh Firas , Alazzeh Awfa , Hijazi Haifa , Wazzan Haneen , Jawharji Monya , Jazar Abdelelah , Filimban Amira , Alshamrani Ali , Labani Mai , Hasanain Taghreed , Obeidat Ahmad
Published: January 2018

The objective of the study was to find the determinants related to not breastfeeding (BF) and others related to the delay in the early initiation of BF in the Mecca region, Saudi Arabia. A cross-sectional study in the Maternity and Children Hospital and primary healthcare centers was performed. A questionnaire was filled by dietitians to 814 asymptomatic Saudi mothers. Determinants related to not BF and the delay in the early initiation of BF were determined by binary logistic regression, and the odds ratio (OR) and 95% confidence interval (CI) were determined. Significant factors associated with not BF were not rooming-in infants in the mother’s room (OR: 2.37; 95% CI: 1.66–3.41) and using a pacifier (OR: 1.62; 95% CI: 1.13–2.33). The most significant determinant of the early initiation of BF was the initiation of bottle feeding (OR: 18.16; 95% CI: 10.51–31.4), followed by not rooming-in infants in the mother’s room (OR: 2.2; 95% CI: 1.52–3.18), initiation of partial feeding (OR: 1.89; 95% CI: 1.3–2.74), uninformed mothers regarding the importance of BF (OR: 1.56; 95% CI: 1.04–2.35), and cesarean sections (OR:1.42; 95% CI: 1.02–1.98). Risk factors affecting BF and the early initiation of BF in Mecca City should be highlighted in national campaigns to increase mothers’ awareness and promote BF practice.
The Impact of Pollution on Skin and Proper Efficacy Testing for Anti-Pollution Claims
Authors: Rembiesa Jadwiga , Ruzgas Tautgirdas , Engblom Johan , Holefors Anna
Published: January 2018

Exposure to pollution can cause oxidative stress, premature ageing, inflammation, and diseases. Since most of us are exposed to pollution, protection is important. This can be achieved through skin protection or through protection with respect to food and food supplements. There is a wide range of products on the market with anti-pollution claims. However, it is important that these claims are thoroughly validated by proper efficacy testing. When skin cells are exposed to pollution factors, changes in a number of skin properties can be observed, such as lipid composition, lipid and protein oxidation, pH, sebum secretion rate, oxidative stress, inflammation markers, and collagen and elastin levels. These can be measured and used as markers to verify anti-pollution claims. In the present review, we summarize some of the most important in vitro and in vivo tests that are used to determine if an ingredient or formulation has anti-pollution efficacy.
SUMOylation Regulates Transcription by the Progesterone Receptor A Isoform in a Target Gene Selective Manner
Authors: Abdel-Hafiz Hany , Dudevoir Michelle , Perez Daniel , Abdel-Hafiz Mohamed , Horwitz Kathryn
Published: January 2018

Luminal breast cancers express estrogen (ER) and progesterone (PR) receptors, and respond to endocrine therapies. However, some ER+PR+ tumors display intrinsic or acquired resistance, possibly related to PR. Two PR isoforms, PR-A and PR-B, regulate distinct gene subsets that may differentially influence tumor fate. A high PR-A:PR-B ratio is associated with poor prognosis and tamoxifen resistance. We speculate that excessive PR-A marks tumors that will relapse early. Here we address mechanisms by which PR-A regulate transcription, focusing on SUMOylation. We use receptor mutants and synthetic promoter/reporters to show that SUMOylation deficiency or the deSUMOylase SENP1 enhance transcription by PR-A, independent of the receptors’ dimerization interface or DNA binding domain. De-SUMOylation exposes the agonist properties of the antiprogestin RU486. Thus, on synthetic promoters, SUMOylation functions as an independent brake on transcription by PR-A. What about PR-A SUMOylation of endogenous human breast cancer genes? To study these, we used gene expression profiling. Surprisingly, PR-A SUMOylation influences progestin target genes differentially, with some upregulated, others down-regulated, and others unaffected. Hormone-independent gene regulation is also PR-A SUMOylation dependent. Several SUMOylated genes were analyzed in clinical breast cancer database. In sum, we show that SUMOylation does not simply repress PR-A. Rather it regulates PR-A activity in a target selective manner including genes associated with poor prognosis, shortened survival, and metastasis.
Composite Likelihood Methods Based on Minimum Density Power Divergence Estimator
Authors: Castilla Elena , Martín Nirian , Pardo Leandro , Zografos Konstantinos
Published: January 2018

In this paper, a robust version of the Wald test statistic for composite likelihood is considered by using the composite minimum density power divergence estimator instead of the composite maximum likelihood estimator. This new family of test statistics will be called Wald-type test statistics. The problem of testing a simple and a composite null hypothesis is considered, and the robustness is studied on the basis of a simulation study. The composite minimum density power divergence estimator is also introduced, and its asymptotic properties are studied.
Improving the Success of First Term General Chemistry Students at a Liberal Arts Institution
Authors: Stone Kari , Shaner Sarah , Fendrick Carol
Published: January 2018

General Chemistry is a high impact course at Benedictine University where a large enrollment of ~250 students each year, coupled with low pass rates of a particularly vulnerable student population from a retention point of view (i.e., first-year college students), make it a strategic course on which to focus innovative pedagogical development. Although our institution is not alone in the challenges that this particular course presents, we have prioritized implementing interventional strategies targeting academically underprepared students to increase their success by providing a preparatory course prior to this gateway course. Focusing on the persistence framework to guide curricular decisions, progress towards aligning our general chemistry curriculum to the academic profile of our students has afforded much higher pass rates than even two years ago.
Antenna Design by Means of the Fruit Fly Optimization Algorithm
Authors: Polo-López Lucas , Córcoles Juan , Ruiz-Cruz Jorge
Published: January 2018

In this work a heuristic optimization algorithm known as the Fruit fly Optimization Algorithm is applied to antenna design problems. The original formulation of the algorithm is presented and it is adapted to array factor and horn antenna optimization problems. Specifically, it is applied to the array factor synthesis of uniformly-fed, non-equispaced arrays and to the profile optimization of multimode horn antennas. Several numerical examples are presented and the obtained results are compared with those provided by a deterministic optimization based on a simplex method and another well-known heuristic approach, the Genetic Algorithm.
H∞ Robust Control of an LCL-Type Grid-Connected Inverter with Large-Scale Grid Impedance Perturbation
Authors: Wang Yingjie , Wang Jiashi , Zeng Wei , Liu Haiyuan , Chai Yushuo
Published: January 2018

In the distributed power generation system (DPGS), there may be a large range perturbation values of equivalent grid impedance at the point of common coupling (PCC). Perturbation of the impedance will cause resonant frequency variation of the Inductance Capacitance Inductance (LCL) filter on a large scale, affecting the quality of the grid current of the grid-connected inverter (GCI) and even causing resonance. To deal with this problem, a novel H∞ robust control strategy based on mixed-sensitivity optimization is proposed in this paper. Its generalized controlled object is augmented by properly selecting weighting functions in order to consider both tracking performance around power frequency and the stability margin in a high frequency of the GCI. For convenient implementation, the H∞ robust controller is simplified by model reduction from the seventh order to the third order. By comparison with a traditional control strategy with a quasi-proportional resonance controller, the proposed H∞ robust control strategy avoids crossing 180 degrees at the resonant frequency point in the phase frequency characteristic of current loop, and moves the phase frequency characteristic left. It guarantees a sufficient margin of stability throughout the designed range of grid impedance perturbation values and avoids the difficulty of parameter setting. Finally, the experimental results support the theoretical analyses and demonstrate the feasibility of the proposed strategy.
Thermodynamic and Environmental Analysis of Scaling up Cogeneration Units Driven by Sugarcane Biomass to Enhance Power Exports
Authors: Guerra João , Cardoso Fernando , Nogueira Alex , Kulay Luiz
Published: January 2018

When manual harvesting of sugarcane was discontinued in many regions of Brazil, interest in power generation by burning the bagasse and straw in cogeneration units rose. Exergy analysis is often applied to increase the thermodynamic yield of these plants by identifying irreversibility and work availability. Conversely, pressure for adopting clean energy requires these systems to be evaluated for suitable environmental performance. This study identified and discussed the thermodynamic and environmental effects of scaling up systems that operate according Rankine cycle with reheating. Ten scenarios have been designed considering different levels of steam pressure and addition rates of straw remaining in the sugarcane cultivation. The thermodynamic analysis revealed a 37% improvement in the exergy efficiency and 63% of increasing in power generation to raise the steam pressure from 20 to 100 bar. Moreover, the use of 50% of residual straw into units operating at 100 bar can more than double the amount of electricity exported. If addressed considering a life cycle perspective, the use of straw improves the environmental performance of the cogeneration for Climate Change and Particle Matter Formation but provides additional impacts in terms of Water and Fossil resources depletions.
Anisotropy in Thermal Recovery of Oil Shale—Part 1: Thermal Conductivity, Wave Velocity and Crack Propagation
Authors: Wang Guoying , Yang Dong , Kang Zhiqin , Zhao Jing
Published: January 2018

In this paper, the evolution of thermal conductivity, wave velocity and microscopic crack propagation both parallel and perpendicular to the bedding plane in anisotropic rock oil shale were studied at temperatures ranging from room temperature to 600 °C. The results show that the thermal conductivity of the perpendicular to bedding direction (KPER) (PER: perpendicular to beeding direction), wave velocity of perpendicular to bedding diretion (VPER), thermal conduction coefficient of parallel to beeding direction (KPAR) and wave velocity of parallel to beeding direction (VPAR) (PAR: parallel to bedding direction) decreased with the increase in temperature, but the rates are different. KPER and VPER linearly decreased with increasing temperature from room temperature to 350 °C, with an obvious decrease at 400 °C corresponding to a large number of cracks generated along the bedding direction. KPER, VPER, KPAR and VPAR generally maintained fixed values from 500 °C to 600 °C. 400 °C has been identified as the threshold temperature for anisotropic evolution of oil shale thermal physics. In addition, the relationship between the thermal conductivity and wave velocity based on the anisotropy of oil shale was fitted using linear regression. The research in this paper can provide reference for the efficient thermal recovery of oil shale, thermal recovery of heavy oil reservoirs and the thermodynamic engineering in other sedimentary rocks.
Study on the Evaluation Index System and Evaluation Method of Voltage Stability of Distribution Network with High DG Penetration
Authors: Tu Jingjing , Yin Zhongdong , Xu Yonghai
Published: January 2018

With the development of new energy technologies, distributed generation (DG) plays a growing role in power distribution networks. Although it solves the power supply problem in some areas, it also poses a challenge to the traditional power grid. To help with this problem, we establish a static voltage stability analysis model for high penetration DG, taking into account its large capacity, and the high fluctuations of its output. Based on the theoretical analysis and the mathematical derivation, we propose an improved voltage stability evaluation index (IVSE) accounting for DG. Finally, using the typical circuit of the IEEE 33 & 69 node system, we simulate high penetration DG access in different locations and capacities. In the simulations, the traditional power flow equation is modified by a continuous parametric equation accounting for DG. Based on consideration of the system transmission power limit, voltage stability margin and system loss, the value of IVSE is demonstrated, in comparison with the traditional index. Thus, we verify that the IVSE index is easy to understand, simple to calculate, and highly versatile.
Study of an Altered Magnetic Circuit of a Permanent Magnet Linear Generator for Wave Power
Authors: Leijon Jennifer , Sjölund Jonathan , Ekergård Boel , Boström Cecilia , Eriksson Sandra , Temiz Irina , Leijon Mats
Published: January 2018

The wave energy converter (WEC) studied and developed at Uppsala University in Sweden is a point absorbing buoy connected to a linear generator (LG) on the seabed. Previous studies have improved the sustainability of the generator, changing its magnets from Nd2Fe14B-magnets to ferrites. In this paper, the magnetic circuit of the linear generator is further studied. Ferrite magnets of two different types (Y30 and Y40) are studied along with different shapes of pole shoes for the system. The finite element method (FEM) simulations in a program called Ace are performed. The results show that a linear generator including both Y30 and Y40 magnets and shortened T-shaped pole shoes can generate a similar magnetic energy in the airgap as a linear generator only containing Y40 magnets and rectangular pole shoes. This shows that the magnetic circuit can be altered, opening up sizes and strengths of magnets for different retailers, and thereby possibly lowering magnet cost and transportation. This work was previously presented as a conference at the European Wave and Tidal Energy Conference (EWTEC) 2017 in Cork, Ireland; this manuscript has been carefully revised and some discussions, on magnet costs for example, have been added to this paper.
Power Estimation of Multiple Two-State Loads Using A Probabilistic Non-Intrusive Approach
Authors: Henao Nilson , Agbossou Kodjo , Kelouwani Sousso , Hosseini Sayed Saeed , Fournier Michael
Published: January 2018

This paper investigates a non-intrusive approach of retrieving electric space heater (ESH) power profiles from a residential aggregated signal. In cold-climate regions with heating appliances controlled by electronic thermostats, an accurate non-intrusive recognition of power profiles is a challenging task. Accordingly, a robust disaggregation approach based on the difference factorial hidden Markov model (DFHMM) and the Kronecker operation is contributed. The proposed method aims to uncover the underlying stochastic tow-state models of ESHs using their common prior knowledge. The major advantage of the developed load-monitoring architecture consists of modeling simplicity and inference as well as load-detection efficacy in the presence of perturbations from other unknown loads. The experimental results prove the effectiveness of the method in manipulating the challenging case of multiple two-state loads with a high event overlapping probability.
Digital Generator Control Unit Design for a Variable Frequency Synchronous Generator in MEA
Authors: Li Weilin , Yang Yang , Zhang Xiaobin
Published: January 2018

Variable frequency power generation systems have been adopted for modern aircraft power systems, thus, a new generator control unit (GCU) must be designed to regulate the output voltage and obtain high quality power supply under a wide frequency range from 360 Hz to 800 Hz. In this paper, a dual digital signal processor (DSP) structure-based GCU was proposed. Multi-loop control structure was adopted with the controller parameters varying adaptively at different working conditions to obtain better performance. Different root-mean-square (RMS) calculation algorithms have been compared and the final RMS calculation scheme was determined to realize the trade-off between accuracy and computing efficiency. Experimental results show considerable performance improvements of the generator output voltage under various operating conditions with the proposed GCU.
Renewable Energy Assisted Traffic Aware Cellular Base Station Energy Cooperation
Authors: Ahmed Faran , Naeem Muhammad , Ejaz Waleed , Iqbal Muhammad , Anpalagan Alagan , Kim Hyung
Published: January 2018

With global concern for climate change, and for cutting down the energy cost, especially in off grid areas, use of renewable energy has been gaining widespread attention in many areas including cellular communication. The base station (BS) has emerged as a strong candidate for the integration of renewable energy sources (RES), particularly solar and wind. The incorporation of renewable energy opens many possibilities for energy conservation through strategies such as energy cooperation between BSs during the off-peak hours, when the energy harvested from renewable energy sources may become surplus. In this paper, we present the case for cellular BSs enabled with renewable energy sources (RES) to have an arrangement in which the BS provide surplus energy to a neighboring BS, thus minimizing the use of conventional energy. A realistic objective is developed for northern region of Pakistan, which entails modeling of solar panels and wind-turbine according to the average solar irradiation and wind speed of the region. We also model the dynamic load of the BS, which depicts temporal fluctuations with traffic variations. Based on these models we initiate an energy cooperation scheme between the BS in which an energy cost minimization framework is mathematically modeled and solved through the interior point method algorithm. Results are obtained for different times of the year for different number of base stations showing respective energy cost savings.
Coordinated Control Schemes of Super-Capacitor and Kinetic Energy of DFIG for System Frequency Support
Authors: Xiong Liansong , Li Yujun , Zhu Yixin , Yang Ping , Xu Zhirong
Published: January 2018

This paper mainly focuses on how to provide frequency supports by the doubly fed induction generator (DFIG) during system disturbances. Two coordinated controls that enable system frequency supports by DFIG-based wind turbines (WTs) are proposed in this paper. The first control scheme seeks to render system support via simultaneously utilizing the energy from the installed super-capacitor between the back-to-back converter of DFIG, and WT rotational kinetic energy (KE). The second one stabilizes system frequency by firstly exerting the installed super-capacitor energy and then WT rotational KE via a unique cascading control. Both proposed coordinated control schemes jointly utilize two virtual inertia sources, namely super-capacitor in the DFIG and rotor rotational mass in the WT to fast provide system frequency support. However, the second proposed one stands itself out by reducing its impaired impacts on the overall wind energy production. Two proposed controls on rapidly providing frequency support are effectively verified and compared in detail by different system disturbances in the DIgSILENT/Powerfactory software.
The Recurrence Interval Difference of Power Load in Heavy/Light Industries of China
Authors: Zhang Chi , Pu Zhengning , Fu Jiasha
Published: January 2018

The significant fluctuation of industrial electricity consumption has a high impact on power load, which makes the research on recurrence intervals between extreme events of theoretical and practical significance. The study uses a high-frequency data of heavy and light industries and employs recurrence interval analysis in different thresholds. We find that the reoccurrence interval of volatility can fit with the stretched exponential function and the probability density functions of recurrence intervals in various thresholds shows a scaling behavior. Then, the conditional probability density function and the multifractal detrended fluctuation analysis demonstrate the existence of short-range correlation, long-range correlation, and multifractal properties, respectively. We further construct a hazard function, introduce recurrence intervals into VaR calculation and establish a functional relationship between average recurrence interval and threshold. Following this result, we also shed light on policy discussion for multi-industrial electricity supply management.
Impacts of Water Flow Rate on Freezing Prevention of Air-Cooled Heat Exchangers in Power Plants
Authors: Guo Yonghong , Wei Huimin , Yang Xiaoru , Wang Weijia , Du Xiaoze , Yang Lijun
Published: January 2018

Under cold ambient conditions, the freezing risk of air-cooled heat exchangers, especially the frontal finned tube bundles, has been a critical concern in power plants. Based on the freezing conditions of the cooling deltas under windy conditions, the flow and heat transfer characteristics of natural draft dry cooling system (NDDCS) with 30%, 40% and 50% increased water flow rates are investigated in this work, and the outlet circulating water temperatures of the easily freezing cooling deltas and sectors are obtained. The results show that the deltas in the middle front and rear sectors become free from freezing at all wind speeds when the circulating water flow rate is increased. For the frontal sector with increased water flow rate, the outlet water temperatures of deltas increase conspicuously at 4 m/s and 8 m/s, while as the wind speed rises to 16 m/s, these deltas still face serious freezing risks due to the huge heat rejection to ambient air. Therefore, freezing prevention of air-cooled NDDCS heat exchangers can be achieved by increasing the water flow rates at small wind speeds, while as the wind speed becomes high, the water flow redistribution is suggested for the frontal and middle sectors due to their big performance difference.
Riverine Water Quality Response to Precipitation and Its Change
Authors: Rostami Sajjad , He Jianxun , Hassan Quazi
Published: January 2018

Surface waters are prone to the influences from both natural condition and anthropogenic activities. The aim of this paper was to study the impacts of one natural variable, precipitation, and its change posed by a changing climate on water quality of three rivers in Alberta, Canada. Eleven water quality parameters monitored during the time period of 1988–2014 were used to investigate the impact of precipitation. The results showed the significant dependence of most water quality parameters as well as river flow on the cumulative antecedent precipitation. Water quality parameters however had different associations with precipitation; and thus they would respond to climate change qualitatively and quantitatively differently in the rivers and at the stations of each river. In general, some water quality parameters such as turbidity and total phosphorus would increase; whereas other parameters would decrease or show no appreciable change under the projected increase of precipitation under the median climate change scenario for the river basins. On all three rivers, the maximum increase (17.20%) and decrease (−1.53%) were projected for turbidity and chloride, respectively, in the 2050s; while the maximum increase (29.68%) and decrease (−2.45%) were calculated for turbidity and chloride, respectively, in the 2080s. The results imply the need to manage riverine water quality considering precipitation and its change under a changing climate.
Effect of Filler Orientation on the Electrical Conductivity of Carbon Fiber/PMMA Composites
Authors: Qu Muchao , Nilsson Fritjof , Schubert Dirk
Published: January 2018

The electrical conductivity of extruded carbon fiber (CF)/Polymethylmethacrylate (PMMA) composites with controlled CF aspect ratio and filler fractions ranging from 0 to 50 vol. % has been investigated and analyzed. The composites were extruded through a capillary rheometer, utilizing either 1-mm or 3-mm diameter extrusion dies, resulting in cylindrical composite filaments of two different diameters. Since the average CF orientation becomes more aligned with the extrusion flow when the diameter of the extrusion dies decreases, the relationship between conductivity and average fiber orientation could therefore be examined. The room temperature conductivities of the extruded filaments as a function of CF fractions were fitted to the McLachlan general effective medium (GEM) equation and the percolation thresholds were determined to 20.0 ± 2.5 vol. % and 32.0 ± 5.9 vol. % for the 3-mm (with CFs oriented less) and 1-mm (with CFs oriented more) filaments, respectively. It turned out that the oriented CFs in the composite shift the percolation threshold to a higher value, however, the conductivity above the percolation threshold is higher for composites with oriented CFs. A novel approach based on the Balberg excluded volume theory was proposed to explain this counterintuitive phenomenon.
Food Composition Databases: Considerations about Complex Food Matrices
Authors: Marconi Stefania , Durazzo Alessandra , Camilli Emanuela , Lisciani Silvia , Gabrielli Paolo , Aguzzi Altero , Gambelli Loretta , Lucarini Massimo , Marletta Luisa
Published: January 2018

Nowadays, many countries have their own national Food Composition Databases, whose continuous updating allows the inclusion of a large number of foods, reflecting the food habits of the population and the growing number of foods on the market in the best way possible. Therefore, particular attention should be directed to the study not only of individual foods or food components but also of the nutritional characteristics of dishes, meals and diets, as they are really consumed. Recently, a reviewed sensitivity in Europe towards the implementation of standardized procedures for generating reliable composition data for composite dishes has been carried out. Although direct chemical analysis is the most accurate method to determine food composition, the nutrient content of complex matrices and composite dishes is often calculated from the nutrient contents of the individual ingredients, considering the different thermal treatments and using some preparation factors. In this context, this paper aims to give an updated picture on Food Composition Databases; in particular, their application regarding complex matrices is examined together with the need to optimize their calculated nutritional values. Results obtained by this calculation should almost always be observed as approximations.
Determination of Vitamin E in Cereal Products and Biscuits by GC-FID
Authors: Pasias Ioannis , Kiriakou Ioannis , Papakonstantinou Lila , Proestos Charalampos
Published: January 2018

A rapid, precise and accurate method for the determination of vitamin E (α-tocopherol) in cereal products and biscuits has been developed. The uncertainty was calculated for the first time, and the methods were performed for different cereal products and biscuits, characterized as “superfoods”. The limits of detection and quantification were calculated. The accuracy and precision were estimated using the certified reference material FAPAS T10112QC, and the determined values were in good accordance with the certified values. The health claims according to the daily reference values for vitamin E were calculated, and the results proved that the majority of the samples examined showed a percentage daily value higher than 15%.
Protein Determination—Method Matters
Authors: Mæhre Hanne , Dalheim Lars , Edvinsen Guro , Elvevoll Edel , Jensen Ida-Johanne
Published: January 2018

The reported protein content of foods depends on the analytical method used for determination, making a direct comparison between studies difficult. The aim of this study was to examine and compare protein analytical methods. Some of these methods require extraction preceding analysis. The efficacy of protein extraction differs depending on food matrices and thus extraction yield was determined. Overall, most analytical methods overestimated the protein contents. The inaccuracies were linked to indirect measurements, i.e. nitrogen determination and subsequent conversion to protein, or interference from other chemical substances. Amino acid analysis is the only protein analysis method where interfering substances do not affect the results. Although there is potential for improvement in regards to the hydrolysis method, we recommend that this method should be the preferred for food protein determination.
Groundwater Natural Contamination by Toluene in Beja and Faro Districts, Portugal
Authors: Barberes Gabriel , Pena dos Reis Rui , Spigolon André , Fonseca Paulo , Bandeira de Mello Carlos , Barata Maria
Published: January 2018

The focus area is located along Beja and Faro districts (southwestern of Portugal), where the Baixo Alentejo Flysch Group exists, is composed of the Mértola, Mira, and Brejeira Formations. The aim of this article is to characterize the groundwater contamination by toluene, one of the petroleum products that may originate from natural petroleum systems and have been introduced into the environment by natural seepage. For this study, twenty soil samples and thirty-one water samples were collected, in 2016, from artesian wells, boreholes, and springs, and analyzed in a GC-FID system. Sampling was performed using headspace vials, with distilled water and a bactericide to inhibit any bacterial activities. The results showed that 93.5% of water samples range between 1000 and 6000 μg/L, and 55% are higher than 3000 μg/L of toluene concentration. In soil samples, amounts of toluene are less than 1000 μg/L in general. These levels are much higher than the World Health Organization health-based guideline for drinkable water (700 μg/L) and higher than those usually found in other places, being only comparable with values from severe industrial contamination. Contaminated groundwater represents a serious concern for human health, and residents should be informed to avoid drinking contaminated ground water or using it for other domestic proposes.
Antibiotic Resistance of Acinetobacter spp. Isolates from the River Danube: Susceptibility Stays High
Authors: Kittinger Clemens , Kirschner Alexander , Lipp Michaela , Baumert Rita , Mascher Franz , Farnleitner Andreas , Zarfel Gernot
Published: January 2018

Acinetobacter spp. occur naturally in many different habitats, including food, soil, and surface waters. In clinical settings, Acinetobacter poses an increasing health problem, causing infections with limited to no antibiotic therapeutic options left. The presence of human generated multidrug resistant strains is well documented but the extent to how widely they are distributed within the Acinetobacter population is unknown. In this study, Acinetobacter spp. were isolated from water samples at 14 sites of the whole course of the river Danube. Susceptibility testing was carried out for 14 clinically relevant antibiotics from six different antibiotic classes. Isolates showing a carbapenem resistance phenotype were screened with PCR and sequencing for the underlying resistance mechanism of carbapenem resistance. From the Danube river water, 262 Acinetobacter were isolated, the most common species was Acinetobacter baumannii with 135 isolates. Carbapenem and multiresistant isolates were rare but one isolate could be found which was only susceptible to colistin. The genetic background of carbapenem resistance was mostly based on typical Acinetobacter OXA enzymes but also on VIM-2. The population of Acinetobacter (baumannii and non-baumannii) revealed a significant proportion of human-generated antibiotic resistance and multiresistance, but the majority of the isolates stayed susceptible to most of the tested antibiotics.
Application of SCM with Bayesian B-Spline to Spatio-Temporal Analysis of Hypertension in China
Authors: Ye Zirong , Xu Li , Zhou Zi , Wu Yafei , Fang Ya
Published: January 2018

Most previous research on the disparities of hypertension risk has neither simultaneously explored the spatio-temporal disparities nor considered the spatial information contained in the samples, thus the estimated results may be unreliable. Our study was based on the China Health and Nutrition Survey (CHNS), including residents over 12 years old in seven provinces from 1991 to 2011. Bayesian B-spline was used in the extended shared component model (SCM) for fitting temporal-related variation to explore spatio-temporal distribution in the odds ratio (OR) of hypertension, reveal gender variation, and explore latent risk factors. Our results revealed that the prevalence of hypertension increased from 14.09% in 1991 to 32.37% in 2011, with men experiencing a more obvious change than women. From a spatial perspective, a standardized prevalence ratio (SPR) remaining at a high level was found in Henan and Shandong for both men and women. Meanwhile, before 1997, the temporal distribution of hypertension risk for both men and women remained low. After that, notably since 2004, the OR of hypertension in each province increased to a relatively high level, especially in Northern China. Notably, the OR of hypertension in Shandong and Jiangsu, which was over 1.2, continuously stood out after 2004 for males, while that in Shandong and Guangxi was relatively high for females. The findings suggested that obvious spatial–temporal patterns for hypertension exist in the regions under research and this pattern was quite different between men and women.