bluuebunny/crossref_metadata_2025 huggingface dataset:
Source Apportionment and Data Assimilation in Urban Air Quality Modelling for NO2: The Lyon Case Study
Authors: Nguyen Chi , Soulhac Lionel , Salizzoni Pietro
Published: January 2018

Developing effective strategies for reducing the atmospheric pollutant concentrations below regulatory threshold levels requires identifying the main origins/sources of air pollution. This can be achieved by implementing so called source apportionment methods in atmospheric dispersion models. This study presents the results of a source apportionment module implemented in the SIRANE urban air-quality model. This module uses the tagged species approach and includes two methods, named SA-NO and SA-NOX, in order to evaluate the sources’ contributions to the NO 2 concentrations in air. We also present results of a data assimilation method, named SALS, that uses the source apportionment estimates to improve the accuracy of the SIRANE model results. The source apportionment module and the assimilation method have been tested on a real case study (the urban agglomeration of Lyon, France, for the year 2008) focusing on the NO 2 emissions and concentrations. Results of the source apportionment with the SA-NO and SA-NOX models are similar. Both models show that traffic is the main cause of NO 2 air pollution in the studied area. Results of the SALS data assimilation method highlights its ability in improving the predictions of an urban atmospheric models.
On the Attribution of Changing Reference Evapotranspiration in a Coastal Area of China
Authors: Gu Renying , Zhang Dan , Liao Anhua , Shen Huayu , Zhao Xiaotong , Pan Jingru
Published: January 2018

Reference evapotranspiration (ET0) is a crucial parameter for hydrological modeling, land-atmospheric interaction investigations and agricultural irrigation management. This study investigated changes in ET0 and attributed those changes to climate variations in a coastal area (Zhejiang province) of China by a numerical experiment method. The results indicated that annual ET0 increased significantly (p < 0.05) at a rate of 1.58 mm·year−1 from 1973 to 2013, which was mainly caused by an obvious increase in ET0 in spring. Air temperature and water vapor pressure deficits increased significantly (p < 0.05) at rates of 0.04 °C·year−1 and 0.005 kPa·year−1, respectively, at an annual time scale during the study period, while wind speed and solar radiation decreased significantly (p < 0.05) at rates of −0.01 m/s·year−1 and −3.94 MJ·m−2·day−1·year−1, respectively. The contributions of changes in air temperature, wind speed, water vapor pressure deficits and solar radiation to increases in ET0 were 0.39, −0.56, 2.62 and −0.61 mm·year−1, respectively. The decrease in wind speed and solar radiation negatively affected the increase in ET0, which was offset by the positive effects of the air temperature and water vapor pressure deficits increase, where the water vapor pressure deficits was the dominant factor in increasing ET0 in the coastal area. Moreover, the impact of topography on ET0 was further discussed. ET0 changes at plain stations were approximately 5.4 times those at hill stations, which may be due to the impact of a large water body and the augment of surface roughness from intense human activities in the well-developed plain area. The results are helpful for investigating spatial and temporal changes in the evaporative demand for well-developed regions under energy-limited conditions.
The Effect of Carrier Quantity and Drying Method on the Physical Properties of Apple Juice Powders
Authors: Michalska Anna , Lech Krzysztof
Published: January 2018

The study aimed at the evaluation of the physical properties of apple juice powders mixed with different concentration of maltodextrin obtained by freeze-, vacuum and spray drying methods. Due to the chemical composition of apple juice there was a possibility to obtain apple juice powders by freeze-, spray and vacuum drying, excluding vacuum drying at 40 °C when 15% and 20% of maltodextrin were added. The moisture content of powders was more dependent on the drying method than on the quantity of maltodextrin added. The spray drying process in the context of an increase in maltodextrin quantity resulted in a decrease in the water activity of apple powders, whereas low temperature processes increased its values. Lower values of true density were observed after spray drying in comparison to freeze- and vacuum drying processes. The application of selected drying methods resulted in the formation of different particles’ size of apple powders influencing the bulk density of the products. The highest values of bulk density were indicated for powders obtained by vacuum drying due to the bigger size of the particles (crystalized structure). The porosity of apple juice powders was strictly related to the bulk density. Colour parameters of powders were more influenced by drying techniques than the quantity of maltodextrin (15% up to 35%) added.
The Relationship between Self-Reported Executive Functioning and Risk-Taking Behavior in Urban Homeless Youth
Authors: Piche Joshua , Kaylegian Jaeson , Smith Dale , Hunter Scott
Published: January 2018

Introduction: Almost 2 million U.S. youth are estimated to live on the streets, in shelters, or in other types of temporary housing at some point each year. Both their age and living situations make them more likely to engage in high-risk behaviors, particularly during adolescence, a time of increased risk taking. Much of self-control appears related to the development of the prefrontal cortex, which is at a particularly crucial period of elaboration and refinement during adolescence and emerging adulthood. Executive processes like decision-making, inhibition, planning, and reasoning may be vulnerable to adversity experienced as a result of homelessness and related impoverishment during childhood and adolescence. No study to date, to our knowledge, has directly investigated differences in risk-taking by homeless youth as it relates to their developing executive control. Objective: Examine the relationship between the level of self-reported executive function (EF) and engagement in risk taking behaviors among a sample of shelter-living urban homeless youth. We predicted that homeless youth who have lower levels of self-reported EF would more readily engage in risky behaviors that could lead to negative outcomes. Participants: One hundred and forty-nine youths between 18 and 22 years of age were recruited from homeless agencies in Chicago. Of this study sample, 53% were female and 76% African American. Measures: All participants completed, as part of a broader neuropsychological assessment, the Behavior Rating Inventory of Executive Functioning-Adult Version (BRIEF-A), the National Youth Risk Behavior Survey (YRBS), and the Mini-International Neuropsychiatric Interview (MINI). Analyses: Groups were separated based on level of self-reported EF, with two groups identified: High self-reported EF fell >1 SD above the normative average, and low self-reported EF fell >1 SD below the normative average. All analyses utilized Chi-square and Mann-Whitney tests. Results and Conclusions: Analyses revealed a relationship between the level of self-reported EF and risk taking behaviors in this group of sheltered homeless urban youths. Those with lower self-reported executive functioning had higher rates of engagement in multiple substance-related risk taking behaviors. These findings are important because they are a first step towards identifying contributions to risk-taking behavior in urban homeless youths. Identifying potential factors like low self-reported EF better allows us to potentially intervene, thereby providing focused support to youths who are at higher risk for engaging in problematic behaviors.
An Investigation of Thermal Comfort and Adaptive Behaviors in Naturally Ventilated Residential Buildings in Tropical Climates: A Pilot Study
Authors: Gou Zhonghua , Gamage Wajishani , Lau Stephen , Lau Sunnie
Published: January 2018

This article presents a pilot study of thermal comfort and adaptive behaviors of occupants who live in naturally ventilated dormitories at the campus of the National University of Singapore. A longitudinal survey and field measurement were conducted to measure thermal comfort, adaptive behaviors and indoor environment qualities. This study revealed that occupants living in naturally ventilated buildings in tropics were exposed to higher operative temperatures than what American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) comfort standards recommend for naturally conditioned spaces. However, they still felt that such conditions were acceptable. Two behavioral adjustments were found to have profound impacts on occupants’ acceptance of the imposed heat stresses: (1) increasing the indoor air velocity by turning on mechanical fans and opening the door/windows for cross ventilation, and (2) reducing clothing insulation by changing clothes and dressing in fewer clothes. Higher indoor air velocities were also associated with greater satisfaction with indoor air quality. The future study should develop a statistical model to correlate adaptive behaviors with temperature variations for tropical climates.
Clinical Implementation of Robust Optimization for Craniospinal Irradiation
Authors: Tasson Alexandria , Laack Nadia , Beltran Chris
Published: January 2018

With robust optimization for spot scanning proton therapy now commercially available, the ability exists to account for setup, range, and interfield uncertainties during optimization. Robust optimization is particularly beneficial for craniospinal irradiation (CSI) where the large target volume lends itself to larger setup uncertainties and the need for robust match lines can all be handled with the uncertainty parameters found inside the optimizer. Suggested robust optimization settings, parameters, and image guidance for CSI patients using proton therapy spot scanning are provided. Useful structures are defined and described. Suggestions are given for perturbations to be entered into the optimizer in order to achieve a plan that provides robust target volume coverage and critical structure sparing as well as a robust match line. Interfield offset effects, a concern when using multifield optimization, can also be addressed within the robust optimizer. A robust optimizer can successfully be employed to produce robust match lines, target volume coverage, and critical structure sparing under specified uncertainties. The robust optimizer can also be used to reduce effects arising from interfield uncertainties. Using robust optimization, a plan robust against setup, range, and interfield uncertainties for craniospinal treatments can be created. Utilizing robust optimization allows one to ensure critical structures are spared and target volumes are covered under the desired uncertainty parameters.
Use of Pleuroperitoneal Shunt in Chylothorax Related to Central Line Associated Thrombosis in Sickle Cell Disease
Authors: Spiwak Elizabeth , Wiesenauer Chad , Panigrahi Arun , Raj Ashok
Published: January 2018

Central vein thrombosis as a cause of chylothorax is uncommon, and in a few cases in the literature was related to thrombotic complications of central venous access devices (CVAD). Superior vena cava (SVC) occlusion-induced chylothorax has been described in adult sickle cell disease (SCD) in a setting of chronic indwelling CVAD. There are limited reports on chylothorax induced by central venous thrombosis secondary to chronic CVAD in children with SCD. We describe an 8-year-old male patient, with a history of SCD, maintained on long term erythrocytapheresis for primary prevention of stroke, and whose clinical course was complicated by chylothorax which was successfully treated with a pleuroperitoneal shunt.
Effect of TiN/C Microstructure Composite Layer on the Adhesion of FDLC Film onto Silicon Substrate
Authors: Xiao Jianrong , Gong Chenyang , Qi Meng , Jiang Aihua , Wang Zhiyong , Li Ming , Ma Jiafeng
Published: January 2018

Deposition techniques of direct current and radio-frequency magnetron sputtering were used to separately prepare TiN/C microstructural composite layer and fluorinated diamond-like carbon (FDLC) film on monocrystalline silicon. The aim was to investigate the effects of microstructural composite layers on the adhesion property of FDLC film. The results indicated that the TiN/C microstructural composite layer can distinguish from the substrate and the FDLC film. After adding the composite layers, the film–substrate binding force significantly increased. When the composite film were prepared at a partial pressure of 0.25, the binding force reached 30.5 N, which was greater than the value of 22.6 N for the sample without composite layers. TiN/C in the composite layers intensified the integration with silicon substrate because the C–C bond acted as a bridge linking the FDLC film to the silicon substrate. Furthermore, the bulges on the surface of the composite layers strengthened the physical bonding of the film with silicon substrates.
Damping Properties of Arc Ion Plating NiCrAlY Coating with Vacuum Annealing
Authors: Du Guangyu , Tan Zhen , Li Guohao , Ba Dechun , Liu Kun
Published: January 2018

NiCrAlY coating was prepared on a stainless steel substrate by an arc ion plating machine and the annealing experiments were carried out at different temperatures using a tube furnace. The effects of annealing temperatures on the morphology, structure, chemical composition and phase structure of the coating were characterized by SEM, EDS and XRD, respectively. The change of microstructure is discussed. Dynamic mechanical analyzer results determined the suitable annealing temperature for the best damping performance. The effect of annealing temperature on the microstructure and damping properties of NiCrAlY coating are also discussed. The relationship between annealing temperature and damping properties are explained by microstrcuture, grain size and phase structure.
CuO and CuO/Graphene Nanostructured Thin Films as Counter Electrodes for Pt-Free Dye-Sensitized Solar Cells
Authors: Tsai Chih-Hung , Fei Po-Hsi , Lin Chia-Ming , Shiu Shiao-Long
Published: January 2018

Copper oxide (CuO) and CuO/graphene nanostructured thin films were used as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). CuO and CuO/graphene pastes were prepared and coated on fluorine-doped tin oxide (FTO) glass substrates using a doctor-blade coating method. The substrates were then sintered at 350 °C for 30 min to form CuO and CuO/graphene nanostructures. The material properties of the CuO and CuO/graphene CEs were analyzed using a scanning electron microscope, transmission electron microscope, energy-dispersive spectrometer, thermogravimetric analysis instrument, X-ray diffractometer, Raman spectroscopy, X-ray photoelectron spectrometer, ultraviolet-visible spectrophotometer, and cyclic voltammetry instrument. The CuO and CuO/graphene CEs were used to fabricate DSSCs, and the device characteristics were analyzed using current density–voltage, incident photo-to-current conversion efficiency, and electrochemical impedance spectroscopy measurements. The results showed that when CuO and CuO/graphene were used as the CEs, the device conversion efficiencies were 2.73% and 3.40%, respectively. CuO is a favorable replacement for expensive platinum (Pt) because it features a simple fabrication process and is inexpensive and abundant. Furthermore, graphene, which exhibits high carrier mobility, may be added to enhance the electrical and catalytic abilities of CuO/graphene CEs. This is the first study to examine the use of CuO and CuO/graphene for developing Pt-free CEs in DSSCs.
What Makes Indian Women Look Older—An Exploratory Study on Facial Skin Features
Authors: Merinville Eve , Messaraa Cyril , O’Connor Carla , Grennan Gemma , Mavon Alain
Published: January 2018

It remains important to investigate skin ageing signs across different skin types for targeted solutions. Limited data is available on Indian skin changes throughout ageing, hence three fields were investigated: skin features during the ageing process, their relationship with perceived age and self-declared skin ageing concerns. Photographs, skin topography, colour and biophysical measurements of 202 Indian female volunteers, 30–65 years old, were collected. Another panel of 693 naïve graders, 20–65 years old, estimated the age of photographs previously collected. Associations between 28 skin features and real/perceived age were assessed using linear correlation coefficients. Skin feature scores of an older perceived group were compared versus the scores of a younger perceived group, to establish skin features that lead to an older appearance. Additionally, the naïve graders were asked to rank 12 skin ageing concerns by importance. Twenty-four features correlated with real and perceived age. The ages of the volunteers were overestimated, especially those in their 30s. Skin features related to skin brightness suggested an older look for volunteers in their 30s. From the 40s onwards, wrinkles around the eye area, glabellar and corner of the mouth were also drivers for looking older. In the 50s, features such as upper lip wrinkles, hydration and roughness on the crow’s feet were worse in the older perceived group, while nasolabial folds suggested an older appearance in the 60s. By having identified skin features that worsen with age and contribute to an older perceived face, this research will facilitate the creation of tailored products and communication for Indian women to look after their skin concerns throughout the ageing process.
Coffee Silverskin: A Review on Potential Cosmetic Applications
Authors: Bessada Sílvia , C. Alves Rita , P. P. Oliveira M.
Published: January 2018

Coffee silverskin, the major coffee-roasting by-product, is currently used as fuel and for soil fertilization. However, there are several studies reporting silverskin as a good source of bioactive compounds that can be extracted and further used by cosmetic industry. Its high antioxidant potential may be due to the synergistic interaction of chlorogenic acids (1–6%), caffeine (0.8–1.25%), and melanoidins (17–23%), among other antioxidant compounds. The bioactive compounds of silverskin can answer to the new fields of cosmetic industry on natural active ingredient resources that improve health skin appearance, counteract skin aging and related diseases, in an environmentally friendly approach. Skin aging is a complex process associated with oxidative metabolism and reactive oxygen species (ROS) generation. ROS production increase matrix metalloproteinases (MMPs), as well as pro-inflammatory mediators, resulting in consequent skin damage and aging. To counteract this process, cosmetic industry is looking for compounds able to increase MMP inhibitory activities, hyaluronidase inhibitory activity, expression of collagen and elastase inhibitory activity, as potential bioactive ingredients with anti-aging purposes. This review focuses on skin aging factors and the potential anti-aging, anti-inflammatory, antimicrobial, anti-cellulite and anti-hair loss activity, as well as protection against UV damage, of coffee silverskin and their bioactive compounds.
Liouvillian of the Open STIRAP Problem
Authors: Mathisen Thomas , Larson Jonas
Published: January 2018

With the corresponding Liouvillian as a starting point, we demonstrate two seemingly new phenomena of the STIRAP problem when subjected to irreversible losses. It is argued that both of these can be understood from an underlying Zeno effect, and in particular both can be viewed as if the environment assists the STIRAP population transfer. The first of these is found for relative strong dephasing, and, in the language of the Liouvillian, it is explained from the explicit form of the matrix generating the time-evolution; the coherence terms of the state decay off, which prohibits further population transfer. For pure dissipation, another Zeno effect is found, where the presence of a non-zero Liouvillian gap protects the system’s (adiabatic) state from non-adiabatic excitations. In contrast to full Zeno freezing of the evolution, which is often found in many problems without explicit time-dependence, here, the freezing takes place in the adiabatic basis such that the system still evolves but adiabatically.
Quality of the ECEC Workforce in Romania: Empirical Evidence from Parents’ Experiences
Authors: Matei Aniela , Ghenţa Mihaela
Published: January 2018

The quality of the early childhood workforce is central to service provision in this area, being a major factor in determining children’s development over the course of their lives. Specific skills and competencies are expected from early childhood education and care (ECEC) workforce. Well-trained staff from ECEC settings are an extremely important factor in providing high-quality services which will positively influence the outcomes of children. The present paper analyses the quality of early childhood education and care workforce from the parents’ perspective in the context of Romania’s early childhood reform agenda. A critical review of the specific situation of the early childhood system in relation to the workforce from this sector is made in the first part of the paper in order to highlight the complexity of this issue. In the second part, the authors will present the results of empirical research developed in 2017 using qualitative and quantitative methods in order to assess the activity of early childhood education and care staff. The main challenges in this field as they emerge from research will be analyzed, the findings having implications for policy-makers and practitioners in the field of ECEC services.
The Impact of Antenna Height on 3D Channel: A Ray Launching Based Analysis
Authors: Hong Qi , Zhang Jiliang , Zheng Hui , Li Hao , Hu Haonan , Zhang Baoling , Lai Zhihua , Zhang Jie
Published: January 2018

Three-dimensional (3D) multi-input-multi-output (MIMO) is one of the enabling technologies for next-generation mobile communication. As the elevation angle in the 3D MIMO channel model might vary against the height of the base station (BS) antenna, it should be considered within channel modeling. In this paper, the impact of antenna height on the channel characteristics of the 3D MIMO channel is investigated by using the intelligent ray launching algorithm (IRLA). Three typical street scenarios, i.e., the straight street, the forked road, and the crossroad, are selected as benchmarks. The joint and marginal probability density functions (PDFs) of both the elevation angle of departure (EAoD) and the elevation angle of arrival (EAoA) are obtained through simulations. Moreover, the elevation angle spread (AS) and the elevation delay spread (DS) under various antenna heights are jointly discussed. Simulation results show that the characteristics of the PDFs of EAoD will vary under different street scenarios. It is observed that in order to obtain the maximum or minimum value of the AS and the DS, the BS antenna should be deployed at half of the building height.
High-Precision Speed Control Based on Multiple Phase-Shift Resonant Controllers for Gimbal System in MSCMG
Authors: Feng Jian , Wang Qing , Liu Kun
Published: January 2018

The high precision speed control of gimbal servo system in magnetically suspended control moment gyro (MSCMG) suffers from periodic torque disturbances, which lead to periodic fluctuations in speed control. This paper proposes a novel multiple phase-shift resonant controller (MPRC) for a gimbal servo system to suppress the periodic torque ripples whose frequencies vary with the operational speed of the gimbal servo motor and high-speed motor. First, the periodic torque ripples caused by cogging torque, flux harmonics and the dynamic unbalance of the high speed rotor are analyzed. Second, the principle and structure of MPRC parallel with proportional integral (PI) controllers are discussed. The design and stability analysis of the proposed MPRC plus PI control scheme are given both for the current loop and speed loop. The closed-loop stability is ensured by adjusting the phase in the entire operational speed range. Finally, the effectiveness of the proposed control method is verified through simulation and experimental results.
Performance Investigation and Optimization of a Novel Hybrid Saturated-Core Fault-Current Limiter Considering the Leakage Effect
Authors: Wei Liangliang , Chen Baichao , Liu Yushun , Tian Cuihua , Yuan Jiaxin , Bu Yuxin , Zhu Tianan
Published: January 2018

To reduce the requirement of DC-biasing capacity and improve the biasing ability of a permanent magnet (PM), a novel hybrid saturated-core fault-current limiter (HSCFCL) is proposed in this paper. Compared with traditional saturated-core fault-current limiter (SCFCL), the HSCFCL has the advantages of small size, low DC-biasing capacity, a high biasing ability of the PM and excellent limiting performance. Firstly, the principle and the magnetic circuit model of the HSCFCL are introduced. Then, the improvement of DC-biasing capacity with a PM is analyzed. In addition, the influence of the leakage-flux effect on the biasing ability of the PM is presented in detail, and a small-section optimal structure is proposed to improve the biasing ability of the PM. Finally, to validate the principle and performance of the HSCFCL, various electromagnetic simulations, optimization studies and experiments are carried out. The simulation and experimental results demonstrate the effectiveness of the proposed method.
Flux-Angle-Difference Feedback Control for the Brushless Doubly Fed Machine
Authors: Xia Chaoying , Hou Xiaoxin , Chen Feng
Published: January 2018

In direct torque control (DTC) of the brushless doubly fed machine (BDFM) system, the inverter switching voltage vectors cannot always meet the control requirements, and the torque will lose control. For the losing control problem, this paper presents a solution of indirectly controlling torque by controlling the angle difference between the power motor (PM) stator flux and the control motor (CM) stator flux (called as the flux-angle-difference). Firstly, based on the CM static coordinate system BDFM model, the derivative equations of CM stator flux amplitude, the torque, and the flux-angle-difference are deduced. The losing control problem of BDFM’s DTC is studied by utilizing the CM stator flux amplitude and the torque derivatives. From the flux-angle-difference derivative, it is found that the phase angles of the flux-angle-difference derivative curves remain unchanged. Based on this property, by replacing the torque hysteresis comparator of conventional DTC with a flux-angle-difference hysteresis comparator, a modified control strategy called flux-angle-difference feedback control (FADFC) is proposed to solve the losing control problem. Finally, the validity and the good dynamic characteristic of the FADFC strategy are verified by simulation results.
Behavior Anomaly Indicators Based on Reference Patterns—Application to the Gearbox and Electrical Generator of a Wind Turbine
Authors: Gil Angel , Sanz-Bobi Miguel , Rodríguez-López Miguel
Published: January 2018

This paper presents indicators of non-expected behavior in components of a wind turbine. These indicators are used to alert about the working conditions of these components that are not usual, according to the normal behavior observed for similar conditions of wind speed and power generated. In order to obtain these indicators, reference patterns of behavior for the components studied were defined. The patterns were obtained from real data of the wind turbine covering all of the possible working conditions. The technique of self-organized maps was used for discovering such reference patterns. Once they were obtained, new data, not included in the training set, was passed through the patterns in order to verify if the behavior observed corresponds or not to that expected. If they do not coincide, an anomaly of behavior is detected than can be useful for soon alert of possible failure mode or at least to know that the component was under working conditions that could cause risk of fault. The periods of unexpected behavior are the base for the indicators proposed in this paper. Real cases to show the elaboration of the indicators, and their corresponding results are provided.
Heating and Cooling Degree-Days Maps of Pakistan
Authors: Amber Khuram , Aslam Muhammad , Ikram Faraz , Kousar Anila , Ali Hafiz , Akram Naveed , Afzal Kamran , Mushtaq Haroon
Published: January 2018

The building sector consumes about 40% of the world’s primary energy. Seasonal climatic conditions have a significant effect on the energy consumption in buildings. One of the famous methods used for decoding this seasonal variation in buildings energy consumption is the “Degree Days Method”. Data has been widely published for the heating and cooling degree days of different countries. Unfortunately, there is very limited and outdated published data for the heating and cooling degree-days of Pakistan. In this study, yearly average heating and cooling degree-days for different regions of Pakistan are established by using 30 year long-term measured data for different base temperatures. The data is presented in tables and figures whereas heating and cooling degree-day maps of Pakistan have been developed.
An Improved Ant Lion Optimization Algorithm and Its Application in Hydraulic Turbine Governing System Parameter Identification
Authors: Tian Tian , Liu Changyu , Guo Qi , Yuan Yi , Li Wei , Yan Qiurong
Published: January 2018

In this paper, an improved ant lion optimization (IALO) algorithm for parameter identification of hydraulic turbine governing system (HTGS) is proposed. In the proposed algorithm, the search space is explored by the ant lion optimization first, and then the domain is searched by the particle swarm optimization (PSO) in each iteration cycle. A chaotic mutation operation namely Logistics map is introduced for the elite to break out of the local optimum. In mutation operation, a serial-parallel combined method is developed to increase the diversity of mutant population. When the proposed IALO algorithm is applied in the parameter identification of HTGS, the comparative simulation results show that the proposed IALO algorithm has the highest accuracy among different optimization algorithms, and the proposed IALO algorithm has a good convergence characteristic and high stability.
Circuit Breaker Rate-of-Rise Recovery Voltage in Ultra-High Voltage Lines with Hybrid Reactive Power Compensation
Authors: Liu Hongshun , Wang Zhen , Yang Jingjing , Li Bin , Ren Ang
Published: January 2018

With the development of ultra-high voltage (UHV) technology, hybrid reactive power compensation (HRPC) will be widely applied in the future. To study the mechanism by which HRPC influences the characteristics of circuit breakers in UHV transmission lines, this paper establishes an improved electromagnetic coupling transmission line model for out-of-phase and short-line faults. Based on the HRPC equivalent model, a simulation analysis was performed on the characteristics of the circuit breaker when a fault occurs. Using an equivalent lumped parameter circuit, the rate-of-rise of recovery voltage (RRRV) computational formula was deduced and computed. The RRRV variation in the circuit breakers in the system, with and without HRPC, was obtained. Given the circuit breaker interruption characteristics, the research results provide an analysis foundation and a theoretical basis for optimizing the HRPC parameters and selecting the arrangements of circuit breakers in an UHV transmission line.
Harmonic Modelling of the Wind Turbine Induction Generator for Dynamic Analysis of Power Quality
Authors: García Héctor , Segundo Juan , Rodríguez-Hernández Osvaldo , Campos-Amezcua Rafael , Jaramillo Oscar
Published: January 2018

Given the increasing integration of wind-based generation systems into the electric grid, efforts have been made to deal with the problem of power quality associated with the intermittent nature of these systems. This paper presents a new modelling approach oriented towards harmonic distortion analysis of the induction machine for wind power applications. The model is developed using companion harmonic circuit modelling, which is a natural approach for analysis of the adverse effects of harmonic distortion in electric power systems, and represents an easier solution method than the well known dynamic harmonic domain, since it solves algebraic equations instead of state-space differential equations. The structure of the companion circuits simplifies both the formulation and solution for power systems with wind-based generation systems. This approach is especially useful for analysis of the harmonic interaction in transient and steady states between the wind power generator and the power system, whose interconnection is made through electronic converters. The proposed model allows us to compute the dynamics of the wind turbine, which are influenced by disturbances such as changes in the wind velocity, voltage fluctuations, electric waveform distortion, and mechanical vibrations, among other factors. Moreover, the cross-coupling between harmonic components at different frequencies is considered. The proposed model represents an integral framework of the electrical and mechanical subsystems of a wind turbine, allowing for analysis of the interactions between them, and understanding power quality degradation behaviour as well as causes and consequences, while also giving useful information on the field of simulation and control. To test the performance of the proposed model, a test power system is used to obtain the behaviour of a wind turbine induction generator in response to typical power quality disturbances, i.e., harmonic distortion, and voltage sags and swells. Then, the dynamics of the variables considering their harmonic interactions are analysed.
Flat Concentrator Photovoltaic System with Lateral Displacement Tracking for Residential Rooftops
Authors: Vu Ngoc , Shin Seoyong
Published: January 2018

We present a design for a flat concentrating photovoltaic (CPV) system that requires only lateral displacement for sun-tracking, intended for residential rooftop applications. Compared with flat-plate photovoltaics (PVs), CPV technology is essential for reducing the use of semi-conductor materials, which also enables cheaper solar power generation. Existing CPV designs are more bulky and complex than traditional PV panel techniques and are therefore better suited to solar farms than rooftop use. In this study, we explore an alternate approach, employing a mirror-coated lenslet array, to demonstrate a flat CPV system for rooftop installation. This mirror-coated lenslet array collects solar radiation and concentrates it with a very short focal length. The lateral movement of lenslet focal points according to a changing incident angle of sunlight allows for the use of a lateral displacement tracking mechanism. A square array of solar cells integrated on a transparent sheet is placed on top of a mirror-coated lenslet array to collect focused sunlight and convert it to electricity. The proposed CPV panel can be achieved with a 35 mm thickness. Simulation models were developed using commercial optical design software (LightTools). The simulation demonstrates an optical efficiency of up to 89.5% when the concentration ratio of the system is fixed to 50×. The simplicity of the structure enables cheaper mass production. Our quest for a lateral displacement sun-tracking mechanism also shows that the system has a high tolerance, thereby enabling cost savings by replacing a highly precise, active sun-tracking system with a lower-accuracy system. The presented flat CPV is a strong candidate for a low-cost, high-efficiency solar energy system that can be installed on the rooftops of residential buildings to deliver energy savings.
A New Control Logic for a Wind-Area on the Balancing Authority Area Control Error Limit Standard for Load Frequency Control
Authors: Chang Yekui , Liu Rao , Ba Yu , Li Weidong
Published: January 2018

Nowadays, the Balancing Authority Area Control Error (ACE) Limit (BAAL) Standard has been adopted to replace the Control Performance Standard 2 (CPS2) in the North American power grid. According to the new standard’s mechanism, a new control logic, named “Triggered Monitoring and Graded Regulation” (TM-GR) is proposed. Its purpose is to improve wind power utilization, with good BAAL Standard compliance for load frequency control (LFC). With the TM logic, according to the real-time regulating ability of areas and forecasting results of wind power output, the triggering moments to give orders are found and a defined monitoring interval is set to track the succeeding fluctuation of Area Control Error (ACE). With the GR logic, based on whether or not over-limit frequency and over-limit ACE occur simultaneously, unit output is regulated in different grades. In cooperation with the existing control logic of Control Performance Standard 1 (CPS1), the proposed logic has a higher priority. From the test results, with the proposed control logic, the utilization of wind power output increases and, meanwhile, the area’s control performance meets the Standard BAL-001-2 requirements. The standard deviation of the frequency deviation is less than the target value, and the duration of over-limit ACE and over-limit frequency can both be restricted to be less than 30 min.
Plant Phenology Observation by Students Using Time-Lapse Images: Creation of the Environment and Examination of Its Adequacy
Authors: Nakamura Kazuhiko , Watanabe Ryuichi , Fujiwara Akio , Saito Kaoru , Kobayashi Hill , Sezaki Kaoru
Published: January 2018

For environmental education about climate change issues, selecting events that are already encountered by people as teaching materials is considered effective. Consideration of changes in leafing dates over time provides a useful tool, in particular when children themselves observe plant phenology, which can be achieved using time-lapse imagery. We postulated that creating an environment where this process can be conducted at school would give children a readiness of behavior toward resolution of climate change issues. Verification of how adequately children can undertake the observations is key to establishing the methodology’s effectiveness. In this research, we used time-lapse images from Shiga Heights, Nagano prefecture, Japan, that were taken once per day from 1987 to 2004; in each year from this series, we used the images taken from 27 May to 15 June, inclusive, as these were the dates during which leafing was expected. We created observation sheets and made these and the time-lapse images available for students on the Internet. As a result of our analysis of observations made by 543 students using the observation sheets, we determined that the method had sufficient adequacy for education.
Bringing the Natives Back: Identifying and Alleviating Establishment Limitations of Native Hardwood Species in a Conifer Plantation
Authors: Li Yu-Tsen , Lo Yueh-Hsin , Lin Yi-Ching , Guan Biing , Blanco Juan , You Chi-How
Published: January 2018

To facilitate the reintroduction of five native late-successional Taiwanese Fagaceae species into Japanese cedar (Cryptomeria japonica (D.) Don) plantations, we experimented with methods to alleviate their establishment limitations. We tested different combinations of tree species, seedling development stages, and site preparation techniques. First, we directly sowed both fresh and germinated acorns under both closed and opened (thinned) canopies. Both fresh and germinated acorns survived only six months at most. Wildlife consumption was the most critical factor hindering their survival. We subsequently experimented with different methods for increasing establishment rates, such as thinning in combination with understory control, applying chemical animal repellents to seeds, using physical barriers against seed predators, and using seedlings of different ages. Among the methods experimented, none was effective. The effects of silvicultural treatments to deter seed consumption lasted only the first few weeks after sowing, whereas the effects of physical barriers were inconsistent. We also tested planting 3-month and 1-year-old seedlings. Seedling survival after 9 months was about 20% on average for 3-month-old seedlings but reached 80% for 1-year-old seedlings. Our results suggest that planting seedlings older than six months or establishing physical obstacles to prevent seed predation will be the most effective strategies to reintroduce late-successional hardwood Fagaceae species into Japanese cedar plantations.
Drought-Induced Changes in Wood Density Are Not Prevented by Thinning in Scots Pine Stands
Authors: Candel-Pérez David , Lo Yueh-Hsin , Blanco Juan , Chiu Chih-Ming , Camarero J. , González de Andrés Ester , Imbert J. , Castillo Federico
Published: January 2018

Density is an important wood mechanical property and an indicator of xylem architecture and hydraulic conductivity. It can be influenced by forest management and climate. We studied the impact of thinning and climate variables on annual stem radial growth (ring width and ring density, and their earlywood and latewood components) in two contrasting Scots pine (Pinus sylvestris L.) stands in northern Spain (one continental, one Mediterranean). At each site, three thinning regimes (control or T0, removing 20% basal area or T20, and removing 30% or T30) were randomly applied to nine plots per site (three plots per treatment) in 1999. Thinning was repeated at the Mediterranean site in 2009 (increasing thinning intensity in T30 to 40%). Eight trees per plot were cored in spring 2014. Second thinning at the Mediterranean site and first thinning at the continental site generally caused significantly wider ring (RW), earlywood (EW) and latewood (LW) widths, although no differences between T20 and T30/40 were found, supporting in part the common observation that radial growth is enhanced following thinning as competition for water and nutrients is reduced. At the Mediterranean site, values of latewood density (LD) and maximum density (Dmax) relative to pre-thinning conditions were significantly lower in T0 than in T30. However, at the continental site, relative changes of ring density (RD) and LD were significantly higher in T0 than in T20 and T30. Climate significantly affected not only RW but also RD, with significant RD drops during or right after unusually warm-dry years (e.g., 2003, 2011), which were characterized by LD reductions between 5.4 and 8.0%. Such RD decreases were quickly followed by recovery of pre-drought density values. These results indicate trees temporarily reduce LD as a way to enhance hydraulic conductivity during dry summers. However, climate effects on wood density were site-dependent. We also detected that the thinning effect was not intense enough to prevent drought-induced changes in wood density by altering water availability, but it could help to reduce wood properties fluctuations and therefore maintain more homogeneous wood mechanic features.
Provenance Variation in Phenology and Frost Tolerance in Subalpine Fir (Abies lasiocarpa) Planted in Denmark and Iceland
Authors: Skulason Brynjar , Hansen Ole , Nielsen Ulrik
Published: January 2018

In Iceland and Denmark, there is an interest in planting Abies lasiocarpa for use as Christmas trees. To search for usable genetic material for both countries, 26 provenances of subalpine fir, covering most of its natural range, were planted in eastern Iceland and Jutland, Denmark. Flushing, bud set and survival rates were assessed. Artificial freezing of twigs, from field trials in eastern Iceland and Denmark, was done to rank the provenances for frost tolerance in the spring and autumn. The northernmost provenances showed earliest bud set, highest autumn frost tolerance and a latitudinal cline was delineated. Differences between provenances in flushing and spring frost tolerance were less than that found for bud set and autumn frost tolerance. The southernmost provenances showed earliest flushing and the most spring frost damage on buds. Mortality of single provenances in the field tests could not be attributed to low freezing tolerances in the autumn or spring. The southernmost provenances of Abies lasiocarpa from New Mexico and Arizona showed the highest survival rate in the field trial in East Iceland, while the eastern provenances showed a low survival rate except for two provenances from Utah and Wyoming. The western provenances from Washington state showed the best survival in Denmark, followed by the southernmost provenances.
The Effects of Excluding Coalitions
Authors: Hiller Tobias
Published: January 2018

One problem in cooperative game theory is to model situations when two players refuse to cooperate (or the problem of quarreling members in coalitions). One example of such exclusions is the coalition statements of parliamentary parties. Other situations in which incompatible players affect the outcome are teams in firms and markets, for example. To model these exclusions in cooperative game theory, the excluded coalitions value ( φ E value) was introduced. This value is based on the Shapley value and takes into account that players exclude coalitions with other players. In this article, we deduce some properties of this new value. After some general results, we analyze the apex game that could be interpreted as a team situation and the glove game that models markets where sellers and buyers deal. For team situations, we show that all employees have a common interest for cooperation. On asymmetric markets, excluding coalitions affect the market players of the scarce side to a higher extent.
Subsidence Trends of Volturno River Coastal Plain (Northern Campania, Southern Italy) Inferred by SAR Interferometry Data
Authors: Matano Fabio , Sacchi Marco , Vigliotti Marco , Ruberti Daniela
Published: January 2018

The Volturno Plain is one of the largest alluvial plains of peninsular Italy, which is one of the most susceptible plains to coastal hazards. This area is characterized by both natural and human-induced subsidence. This present study is based on the post-processing, analysis and mapping of the available Persistent Scatterer interferometry datasets. The latter were derived from the combination of both ascending and descending orbits of three different radar satellite systems during an observation period of almost two decades (June 1992–September 2010). The main output of this study is a map of vertical deformation, which provides new insights into the areal variability of the ground deformation processes (subsidence/uplift) of Volturno plain over the last few decades. The vertical displacement values obtained by the post-processing of the interferometric data show that the Volturno river plain is characterized by significant subsidence in the central axial sectors and in the river mouth area. Moderate uplift is detected in the eastern part of the plain, whereas other sectors of the study area are characterized by moderate subsidence and/or stability. On the basis of the analyzed subsoil stratigraphy, we inferred that the subsidence recorded in the Volturno plain is mainly a consequence of a natural process related to the compaction of the fluvial and palustrine deposits that form the alluvial plain. The anthropic influences (e.g., water exploitation, urbanization) are substantially considered to be an additional factor that may enhance subsidence only locally. The uplift mapped in the eastern sector of the plain is related to the tectonic activity. The study of the subsidence in the Volturno plain is a valuable tool for river flood analyses and the assessment of the coastal inundation hazards and related risk mitigation.