bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxic Corporate Culture: Assessing Organizational Processes of Deviancy
Authors: Van Rooij Benjamin , Fine Adam
Published: June 2018

There is widespread recognition that organizational culture matters in corporations involved in systemic crime and wrongdoing. However, we know far less about how to assess and alter toxic elements within a corporate culture. The present paper draws on management science, anthropology, sociology of law, criminology, and social psychology to explain what organizational culture is and how it can sustain illegal and harmful corporate behavior. Through analyzing the corporate cultures at BP, Volkswagen, and Wells Fargo, this paper demonstrates that organizational toxicity does not just exist when corporate norms are directly opposed to legal norms, but also when: (a) it condones, neutralizes, or enables rule breaking; (b) it disables and obstructs compliance; and (c) actual practices contrast expressed compliant values. The paper concludes that detoxing corporate culture requires more than changing leadership or incentive structures. In particular, it requires addressing the structures, values, and practices that enable violations and obstruct compliance within an organization, as well as moving away from a singular focus on liability management (i.e., assigning blame and punishment) to an approach that prioritizes promoting transparency, honesty, and a responsibility to initiate and sustain actual cultural change.
Food Calls in Common Marmosets, Callithrix jacchus, and Evidence That One Is Functionally Referential
Authors: Rogers Lesley J. , Stewart Leanne , Kaplan Gisela
Published: June 2018

We studied three calls of common marmosets, Callithrix jacchus, elicited in the context of food. Call A, but not B or C, had been described previously as a food call. We presented insects (live mealworms or crickets) and fruit (banana or blueberries) and used playbacks of calls. We found that Call C was produced only in response to seeing insects, and not fruit; it consistently signaled the availability of insects (includes mealworms), and more so when this food could be seen but not consumed. Playback of Call C caused the marmosets to stop feeding on a less preferred food (banana) and, instead, go to inspect a location where mealworms had been found previously, providing evidence that it has referential meaning. No such immediate response was elicited on hearing Call A or background noise. Call A differed from C in that it was produced more frequently when the marmosets were consuming the food than when they could only see it, and call A showed no specificity between insects and fruit. Call B was emitted less frequently than the A or C calls and, by the marmosets that were tested alone, most often to crickets. An audience effect occurred, in that all three calls were emitted more often when the marmosets were tested alone than when in pairs. Recognition of the functional significance of marmoset calls can lead to improved husbandry of marmosets in captivity.
SD-EAR: Energy Aware Routing in Software Defined Wireless Sensor Networks
Authors: Banerjee Anuradha , Hussain D. M. Akbar
Published: June 2018

In today’s internet-of-things (IoT) environment, wireless sensor networks (WSNs) have many advantages, with broad applications in different areas including environmental monitoring, maintaining security, etc. However, high energy depletion may lead to node failures in WSNs. In most WSNs, nodes deplete energy mainly because of the flooding and broadcasting of route-request (RREQ) packets, which is essential for route discovery in WSNs. The present article models wireless sensor networks as software-defined wireless sensor networks (SD-WSNs) where the network is divided into multiple clusters or zones, and each zone is controlled by a software-defined network (SDN) controller. The SDN controller is aware of the topology of each zone, and finds out the optimum energy efficient path from any source to any destination inside the zone. For destinations outside of the zone, the SDN controller of the source zone instructs the source to send a message to all of the peripheral nodes in that zone, so that they can forward the message to the peripheral nodes in other zones, and the process goes on until a destination is found. As far as energy-efficient path selection is concerned, the SDN controller of a zone is aware of the connectivity and residual energy of each node. Therefore, it is capable of discovering an optimum energy efficient path from any source to any destination inside as well as outside of the zone of the source. Accordingly, flow tables in different routers are updated dynamically. The task of route discovery is shifted from individual nodes to controllers, and as a result, the flooding of route-requests is completely eliminated. Software-defined energy aware routing (SD-EAR)also proposes an innovative sleeping strategy where exhausted nodes are allowed to go to sleep through a sleep request—sleep grant mechanism. All of these result in huge energy savings in SD-WSN, as shown in the simulation results.
Macro- and Microphysical Characteristics of Precipitating and Non-Precipitating Stratocumulus Clouds over Eastern China
Authors: Li Sicong , Li Yunying , Sun Guorong , Lu Zhixian
Published: June 2018

Stratocumulus (Sc) is the most common cloud type in China. Sc clouds may or may not be accompanied by various types of precipitation that are representative of different macro- and microphysical characteristics. The finely resolved CloudSat data products are used in this study to quantitatively investigate the macro- and microphysical characteristics of precipitating and non-precipitating Sc (PS and NPS, respectively) clouds over Eastern China (EC). Based on statistical information extracted from the CloudSat data, Sc clouds are highly likely to occur alone, in association with liquid precipitation, or in association with drizzle over 25% of EC. The cloud bases of NPS clouds are higher than those of PS clouds, although the latter display higher cloud top heights and thicker cloud thicknesses. The spatial distributions of microphysical characteristics differ between PS and NPS clouds. The magnitudes of microphysical characteristics in NPS clouds are relatively small, whereas the magnitudes of microphysical characteristics in PS clouds are relatively large and peak in response to certain circulation patterns and over certain terrain. In NPS clouds, condensation is the primary mechanism for hydrometeor particle growth, and the liquid water content and effective radius increase with height. Once the particles are too large to be supported by the updrafts, cloud droplets form raindrops. In PS clouds, raindrops increase continuously in size via collision-coalescence processes as they fall, leading to an increase in the liquid water content and effective radius from cloud top to cloud base. The CFRHDs (contoured frequency by relative height diagrams) of radar reflectivity in different cloud thickness indicate the cloud evolution and the precipitation formation process. In thinner clouds, downward particle growth by coalescence and upward particle growth by condensation occur in the upper and lower layers of clouds, respectively. With the increases in cloud thickness, the collision-coalescence process becomes apparent in all cloud layers, and the upward condensation process is less pronounced near the cloud base. Particles can grow for a long period of time and increase to larger sizes in thicker clouds, resulting in increased precipitation frequency. In clouds thicker than 1.92 km, the continuous transition from cloud to drizzle to rain by the collision-coalescence process takes place mostly in the upper layers.
Analysis of Drought Vulnerability Characteristics and Risk Assessment Based on Information Distribution and Diffusion in Southwest China
Authors: Jiang Shouzheng , Yang Ruixiang , Cui Ningbo , Zhao Lu , Liang Chuan
Published: June 2018

Drought vulnerability characteristics and risk assessment form the basis of drought risk management. In this study, the standardized precipitation index (SPI) and drought damage rates (DDR) were combined to analyze drought vulnerability characteristics and drought risk in Southwest China (SC). The information distribution method was applied to estimate the probability density of the drought strength (DS) and the two-dimensional normal information diffusion method was used to construct the vulnerability relationships between DS and drought damage (DD). The risk was then evaluated by combining the probability function of the DS and the DD vulnerability curve. The results showed that the relationship between the DS and the DD was nonlinear in SC and its provinces. With the increase in DS, the degree of DD increased gradually, stabilized, or decreased toward the end. However, the vulnerability characteristics of the different provinces varied widely due to multiple risk-bearing bodies and abilities to resist disasters. The risk values obtained across the range of time scales of the SPI were not significantly different. The yielding probabilities will be reduced for the crop area by 10%, 30%, and 70% due to drought. Compared to a normal year in SC, the probability values were 16.04%, 10.29%, and 2.70%, respectively. These results have the potential to provide a reference for agricultural production and drought risk management.
Towards Multi-Organoid Systems for Drug Screening Applications
Authors: Miranda Cláudia C. , Fernandes Tiago G. , Diogo Maria Margarida , Cabral Joaquim M. S.
Published: June 2018

A low percentage of novel drug candidates succeed and reach the end of the drug discovery pipeline, mainly due to poor initial screening and assessment of the effects of the drug and its metabolites over various tissues in the human body. For that, emerging technologies involving the production of organoids from human pluripotent stem cells (hPSCs) and the use of organ-on-a-chip devices are showing great promise for developing a more reliable, rapid and cost-effective drug discovery process when compared with the current use of animal models. In particular, the possibility of virtually obtaining any type of cell within the human body, in combination with the ability to create patient-specific tissues using human induced pluripotent stem cells (hiPSCs), broadens the horizons in the fields of drug discovery and personalized medicine. In this review, we address the current progress and challenges related to the process of obtaining organoids from different cell lineages emerging from hPSCs, as well as how to create devices that will allow a precise examination of the in vitro effects generated by potential drugs in different organ systems.
Electrochemical (Bio) Sensors for Environmental and Food Analyses
Authors: Honeychurch Kevin C. , Piano Martina
Published: June 2018

In recent years, great progress has been made in the development of sensors and biosensors to meet the demands of environmental and food analysis. In this Special Issue, the state of art and the future trends in the field of environmental and food analyses have been explored. A total of seven papers (three research and four review papers) are included. These are focused on the fabrication and detection of contaminates such as heavy metals, pesticides and food components, including uric acid and 3-hydroxybutyrate. Included in this Issue is a paper dedicated to the experimental determination of the electroactive area of screen-printed electrodes, an important parameter in the development of such sensors.
High and Low Levels of an NTRK2-Driven Genetic Profile Affect Motor- and Cognition-Associated Frontal Gray Matter in Prodromal Huntington’s Disease
Authors: Ciarochi Jennifer , Liu Jingyu , Calhoun Vince , Johnson Hans , Misiura Maria , Bockholt H. , Espinoza Flor , Caprihan Arvind , Plis Sergey , Turner Jessica , Paulsen Jane ,   The PREDICT-HD Investigators and Coordinators of the Huntington Study Group
Published: June 2018

This study assessed how BDNF (brain-derived neurotrophic factor) and other genes involved in its signaling influence brain structure and clinical functioning in pre-diagnosis Huntington’s disease (HD). Parallel independent component analysis (pICA), a multivariate method for identifying correlated patterns in multimodal datasets, was applied to gray matter concentration (GMC) and genomic data from a sizeable PREDICT-HD prodromal cohort (N = 715). pICA identified a genetic component highlighting NTRK2, which encodes BDNF’s TrkB receptor, that correlated with a GMC component including supplementary motor, precentral/premotor cortex, and other frontal areas (p < 0.001); this association appeared to be driven by participants with high or low levels of the genetic profile. The frontal GMC profile correlated with cognitive and motor variables (Trail Making Test A (p = 0.03); Stroop Color (p = 0.017); Stroop Interference (p = 0.04); Symbol Digit Modalities Test (p = 0.031); Total Motor Score (p = 0.01)). A top-weighted NTRK2 variant (rs2277193) was protectively associated with Trail Making Test B (p = 0.007); greater minor allele numbers were linked to a better performance. These results support the idea of a protective role of NTRK2 in prodromal HD, particularly in individuals with certain genotypes, and suggest that this gene may influence the preservation of frontal gray matter that is important for clinical functioning.
Mathematical Explanation and Fault Diagnosis of Low Delta-T Syndrome in Building Chilled Water Systems
Authors: Yan Chengchu , Yang Xiuxiu , Xu Yizhe
Published: June 2018

Low delta-T syndrome often occurs in building chilled water systems, which makes systems fail to operate as efficiently as originally anticipated. Extensive studies have been conducted on the subject of low delta-T syndrome with the aims of investigating the potential causes behind and the ways to keep delta-T high. This paper addresses to explain the causes of degrading delta-T from a mathematic perspective and to analyze the impacts of important operational parameters on the delta-T quantitatively. A simplified global cooling coil model representing the relationship between the total cooling load and the total water flow rate of chilled water systems is developed, which can be used to predict the system delta-T under different load distribution and system operation conditions. It is proved mathematically that the load distribution characteristic is an important factor in influencing the system delta-T of a chilled water system. This finding explains why the system delta-T is always lower than the delta-T of individual coils, particularly under low partial load conditions. A system-level fault detection and diagnosis (FDD) method is proposed for identifying the possible causes of the low delta-T problem. A case study is conducted to validate the proposed global model and FDD method in a real building.
Genomic Landscapes of EBV-Associated Nasopharyngeal Carcinoma vs. HPV-Associated Head and Neck Cancer
Authors: Ngan Hoi-Lam , Wang Lan , Lo Kwok-Wai , Lui Vivian Wai Yan
Published: June 2018

Epstein-Barr virus-positive nasopharyngeal carcinoma (EBV(+) NPC), and human papillomavirus-positive head and neck squamous cell carcinoma (HPV(+) HNSCC) are two distinct types of aggressive head and neck cancers with early age onsets. Their recently identified genomic landscapes by whole-exome sequencing (WES) clearly reveal critical roles of: (1) inflammation via NF-kB activation, (2) survival via PI3K aberrations, and perhaps (3) immune evasion via MHC loss in these cancers as summarized in this review. Immediate outcomes of these WES studies include the identification of potential prognostic biomarkers, and druggable events for these cancers. The impact of these genomic findings on the development of precision medicine and immunotherapies will be discussed. For both of these cancers, the main lethality comes from metastases and disease recurrences which may represent therapy resistance. Thus, potential curing of these cancers still relies on future identification of key genomic drivers and likely druggable events in recurrent and metastatic forms of these intrinsically aggressive cancers of the head and neck.
Understanding Intratumor Heterogeneity and Evolution in NSCLC and Potential New Therapeutic Approach
Authors: Goto Taichiro , Hirotsu Yosuke , Amemiya Kenji , Mochizuki Hitoshi , Omata Masao
Published: June 2018

Advances in innovative technology, including next-generation sequencing, have allowed comprehensive genomic analysis and the elucidation of the genomic aspect of intratumor heterogeneity (ITH). Moreover, models of the evolution of the cancer genome have been proposed by integrating these analyses. Cancer has been considered to accumulate genetic abnormalities for clonal evolution in time and space, and these evolutionary patterns vary depending on the organs of primary sites. Selection pressure is an important determinant of such evolutionary patterns. With weak selection pressure, more diverse clones coexist, and heterogeneity increases. Heterogeneity is maximized when there is no selection pressure; in other words, neutral evolution occurs. Some types of cancer such as lung cancer evolve in conditions that have maintained close to neutral evolution and produce diverse variants. This ITH is a key factor contributing to the lethal outcome of cancer, therapeutic failure, and drug resistance. This factor reaffirms the complexity and subtle adaptability of cancer. It is expected that further understanding of ITH and cancer genome evolution will facilitate the development of new therapeutic strategies to overcome ITH.
Hot Embossing for Whole Teflon Superhydrophobic Surfaces
Authors: Li Jie , Yu Wentao , Zheng Deyin , Zhao Xin , Choi Chang-Hwan , Sun Guangyi
Published: June 2018

In this paper, we report a simple fabrication process of whole Teflon superhydrophobic surfaces, featuring high-aspect-ratio (>20) nanowire structures, using a hot embossing process. An anodic aluminum oxide (AAO) membrane is used as the embossing mold for the fabrication of high-aspect-ratio nanowires directly on a Teflon substrate. First, high-aspect-ratio nanowire structures of Teflon are formed by pressing a fluorinated ethylene propylene (FEP) sheet onto a heated AAO membrane at 340 °C, which is above the melting point of FEP. Experimental results show that the heating time and aspect ratios of nanopores in the AAO mold are critical to the fidelity of the hot embossed nanowire structures. It has also been found that during the de-molding step, a large adhesive force between the AAO mold and the molded FEP greatly prolongs the length of nanowires. Contact angle measurements indicate that Teflon nanowires make the surface superhydrophobic. The reliability and robustness of superhydrophobicity is verified by a long-term (~6.5 h) underwater turbulent channel flow test. After the first step of hot-embossing the Teflon nanowires, microstructures are further superimposed by repeating the hot embossing process, but this time with microstructured silicon substrates as micromolds and at a temperature lower than the melting temperature of the FEP. The results indicate that the hot embossing process is also an effective way to fabricate hierarchical micro/nanostructures of whole Teflon, which can be useful for applications of Teflon material, such as superhydrophobic surfaces.
DNA Barcoding Highlights Cryptic Diversity in the New Zealand Psylloidea (Hemiptera: Sternorrhyncha)
Authors: Martoni Francesco , Bulman Simon , Pitman Andrew , Taylor Gary , Armstrong Karen
Published: June 2018

The insect superfamily Psylloidea (Hemiptera) includes economically important biocontrol agents, pests and plant pathogen vectors, for which a rapid and accurate identification is fundamental for international biosecurity. Australasia is a hot spot for psyllid diversity, but previous species assessments in the region were largely based on morphology and host plant association. Morphological identification of psyllids remains challenging for a wide number of species and for juvenile insects, while a robust molecular framework for identification is not available. Consequently, knowledge of psyllid biology is compromised. Here, incorporating morphological evidence and host plant associations, insects collected from almost 600 primarily New Zealand locations were linked to 67 previously described species. By applying species delimitation methods including GYMC (General Mixed Yule–Coalescent method), PTP (Poisson Tree Processes), mPTP (multi–rate Poisson Tree Processes) and ABGD (Automatic Barcode Gap Discovery) to a dataset composed of 425 cytochrome oxidase I (COI) DNA barcode sequences, further cryptic diversity was revealed among the psyllid collection; more than 20 undescribed taxa are reported here for the first time, resulting in a total of 90 taxa across 21 genera and six families included in this study. Our improved understanding of psyllid diversity in New Zealand revealed new plant host-psyllid associations and geographical variation. The DNA barcode resource will enable future studies of psyllid ecology and more accurate, rapid identifications of psyllids that pose biosecurity threats to Australasia.
Solitary Brain Mass in a Patient with Seizures: An Unexpected Infectious Etiology
Authors: Raja Mohammed , Gonzales Zamora Jose Armando , Hassoun Ali
Published: June 2018

Neurocysticercosis is a parasitosis caused by the larval stage of the pork tapeworm Taenia solium. The diagnosis is challenging as morphology on neuroimaging can be inconclusive and serology is frequently negative. We describe the case of a 24-year old Hispanic man who presented with seizures and loss of consciousness. Magnetic resonance imaging (MRI) showed a cystic mass in right frontal lobe. Work-up that included body computed tomography (CT) scan and Western blot serology for Echinococcus and cysticercosis was unrevealing. He underwent craniotomy with resection of the mass. Histopathology showed fragments of Taenia solium. He was treated with albendazole for 14 days. No further seizures were noted at 6-month follow-up.
Classification of Maize in Complex Smallholder Farming Systems Using UAV Imagery
Authors: Hall Ola , Dahlin Sigrun , Marstorp Håkan , Archila Bustos Maria , Öborn Ingrid , Jirström Magnus
Published: June 2018

Yield estimates and yield gap analysis are important for identifying poor agricultural productivity. Remote sensing holds great promise for measuring yield and thus determining yield gaps. Farming systems in sub-Saharan Africa (SSA) are commonly characterized by small field size, intercropping, different crop species with similar phenologies, and sometimes high cloud frequency during the growing season, all of which pose real challenges to remote sensing. Here, an unmanned aerial vehicle (UAV) system based on a quadcopter equipped with two consumer-grade cameras was used for the delineation and classification of maize plants on smallholder farms in Ghana. Object-oriented image classification methods were applied to the imagery, combined with measures of image texture and intensity, hue, and saturation (IHS), in order to achieve delineation. It was found that the inclusion of a near-infrared (NIR) channel and red–green–blue (RGB) spectra, in combination with texture or IHS, increased the classification accuracy for both single and mosaic images to above 94%. Thus, the system proved suitable for delineating and classifying maize using RGB and NIR imagery and calculating the vegetation fraction, an important parameter in producing yield estimates for heterogeneous smallholder farming systems.
Inferring the Population Mean with Second-Order Information in Online Social Networks
Authors: Chen Saran , Lu Xin , Liu Zhong , Jia Zhongwei
Published: June 2018

With the increasing use of online social networking platforms, online surveys are widely used in many fields, e.g., public health, business and sociology, to collect samples and to infer the population characteristics through self-reported data of respondents. Although the online surveys can protect the privacy of respondents, self-reporting is challenged by a low response rate and unreliable answers when the survey contains sensitive questions, such as drug use, sexual behaviors, abortion or criminal activity. To overcome this limitation, this paper develops an approach that collects the second-order information of the respondents, i.e., asking them about the characteristics of their friends, instead of asking the respondents’ own characteristics directly. Then, we generate the inference about the population variable with the Hansen-Hurwitz estimator for the two classic sampling strategies (simple random sampling or random walk-based sampling). The method is evaluated by simulations on both artificial and real-world networks. Results show that the method is able to generate population estimates with high accuracy without knowing the respondents’ own characteristics, and the biases of estimates under various settings are relatively small and are within acceptable limits. The new method offers an alternative way for implementing surveys online and is expected to be able to collect more reliable data with improved population inference on sensitive variables.
Rolling Bearing Fault Diagnosis Based on Optimal Notch Filter and Enhanced Singular Value Decomposition
Authors: Pang Bin , He Yuling , Tang Guiji , Zhou Chong , Tian Tian
Published: June 2018

The impulsive fault feature signal of rolling bearings at the early failure stage is easily contaminated by the fundamental frequency (i.e., the rotation frequency of the shaft) signal and background noise. To address this problem, this paper puts forward a rolling bearing weak fault diagnosis method with the combination of optimal notch filter and enhanced singular value decomposition. Firstly, in order to eliminate the interference of the fundamental frequency signal, the original signal was processed by the notch filter with the fundamental frequency as the center frequency and with a varying bandwidth to get a series of corresponding notch filter signals. Secondly, the Teager energy entropy index was adopted to adaptively determine the optimal bandwidth to complete the optimal notch filter analysis on the raw vibration signal and obtain the corresponding optimal notch filter signal. Thirdly, an enhanced singular value decomposition de-nosing method was employed to de-noise the optimal notch filter signal. Finally, the envelope spectrum analysis was conducted on the de-noised signal to extract the fault characteristic frequencies. The effectiveness of the presented method was demonstrated via simulation and experiment verifications. In addition, the minimum entropy deconvolution, Kurtogram and Infogram methods were employed for comparisons to show the advantages of the presented method.
Energy and Exergy Analyses of a Solid Oxide Fuel Cell-Gas Turbine-Organic Rankine Cycle Power Plant with Liquefied Natural Gas as Heat Sink
Authors: Ahmadi Mohammad H. , Sadaghiani Mirhadi S. , Pourfayaz Fathollah , Ghazvini Mahyar , Mahian Omid , Mehrpooya Mehdi , Wongwises Somchai
Published: June 2018

An exergy analysis of a novel integrated power system is represented in this study. A Solid Oxide Fuel Cell (SOFC), which has been assisted with a Gas Turbine (GT) and Organic Rankine Cycle (ORC) by employing liquefied natural gas (LNG) as a heat sink in a combined power system is simulated and investigated. Initially in this paper, the integrated power system and the primary concepts of the simulation are described. Subsequently, results of the simulation, exergy analysis, and composite curves of heat exchangers are represented and discussed. The equations of the exergy efficiency and destruction for the main cycle’s units such as compressors, expanders, pumps, evaporators, condensers, reformers, and reactors are presented. According to the results, the highest exergy destruction is contributed to the SOFC reactor, despite its acceptable exergy efficiency which is equal to 75.7%. Moreover, the exergy efficiencies of the ORC cycle and the whole plant are determined to be 64.9% and 39.9%, respectively. It is worth noting that the rational efficiency of the integrated power system is 53.5%. Among all units, the exergy efficiency of the LNG pump is determined to be 11.7% the lowest exergy efficiency among the other investigated components, indicating a great potential for improvements.
Symmetric Logarithmic Derivative of Fermionic Gaussian States
Authors: Carollo Angelo , Spagnolo Bernardo , Valenti Davide
Published: June 2018

In this article, we derive a closed form expression for the symmetric logarithmic derivative of Fermionic Gaussian states. This provides a direct way of computing the quantum Fisher Information for Fermionic Gaussian states. Applications range from quantum Metrology with thermal states to non-equilibrium steady states with Fermionic many-body systems.
Quantification and Analysis of the Irreversible Flow Loss in a Linear Compressor Cascade
Authors: Li Zhiyuan , Du Juan , Ottavy Xavier , Zhang Hongwu
Published: June 2018

A local loss model and an integral loss model are proposed to study the irreversible flow loss mechanism in a linear compressor cascade. The detached eddy simulation model based on the Menter shear stress transport turbulence model (SSTDES) was used to perform the high-fidelity simulations. The flow losses in the cascade with an incidence angle of 2°, 4° and 7° were analyzed. The contours of local loss coefficient can be explained well by the three-dimensional flow structures. The trend of flow loss varying with incidence angle predicted by integral loss is the same as that calculated by total pressure loss coefficient. The integral loss model was used to evaluate the irreversible loss generated in different regions and its varying trend with the flow condition. It as found that the boundary layer shear losses generated near the endwall, the pressure surface and the suction surface are almost identical for the three incidence angles. The secondary flow loss in the wake-flow and blade-passage regions changes dramatically with the flow condition due to the occurrence of corner stall. For this cascade, the secondary flow loss accounts for 26.1%, 48.3% and 64.3% of the total loss for the flow when the incidence angles are 2°, 4° and 7°, respectively. Lastly, the underlying reason for the variation of the secondary flow loss with the incidence angle is explained using the Lc iso-surface method.
The Effect of Scandium Ternary Intergrain Precipitates in Al-Containing High-Entropy Alloys
Authors: Riva Sephira , Mehraban Shahin , Lavery Nicholas P. , Schwarzmüller Stefan , Oeckler Oliver , Brown Stephen G. R. , Yusenko Kirill V.
Published: June 2018

We investigate the effect of alloying with scandium on microstructure, high-temperature phase stability, electron transport, and mechanical properties of the Al2CoCrFeNi, Al0.5CoCrCuFeNi, and AlCoCrCu0.5FeNi high-entropy alloys. Out of the three model alloys, Al2CoCrFeNi adopts a disordered CsCl structure type. Both of the six-component alloys contain a mixture of body-centered cubic (bcc) and face centered cubic (fcc) phases. The comparison between in situ high-temperature powder diffraction data and ex situ data from heat-treated samples highlights the presence of a reversible bcc to fcc transition. The precipitation of a MgZn2-type intermetallic phase along grain boundaries following scandium addition affects all systems differently, but especially enhances the properties of Al2CoCrFeNi. It causes grain refinement; hardness and electrical conductivity increases (up to 20% and 14% respectively) and affects the CsCl-type → fcc equilibrium by moving the transformation to sensibly higher temperatures. The maximum dimensionless thermoelectric figure of merit (ZT) of 0.014 is reached for Al2CoCrFeNi alloyed with 0.3 wt.% Sc at 650 °C.
Cost of Agricultural Business Equity Capital—A Theoretical and Empirical Study for Poland
Authors: Franc-Dąbrowska Justyna , Mądra-Sawicka Magdalena , Bereżnicka Joanna
Published: June 2018

This paper proposes a methodology for calculating the cost of equity for unlisted agricultural companies in Poland. An analysis of a fixed effects panel model was conducted on a sample of 79 agricultural enterprises from the Farm Accountancy Data Network (FADN) field of observation in 2012–2015. The empirical model includes a value of land, agricultural area, depreciation, sale earnings, and payables. The study confirmed that in the valuation of the cost of equity capital in agricultural enterprises, factors that are specific to this sector must be taken into account. As the basic source of production is agricultural land, it must be taken into consideration while estimating the cost of equity capital. This factor was included in the theoretical model.
Study on the Propagation Characteristics of Partial Discharge in Switchgear Based on Near-Field to Far-Field Transformation
Authors: Qi Yang , Fan Yang , Gao Bing , Mengzhuo Yang , Jadoon Ammad , Peng Yu , Jie Tian
Published: June 2018

Ultra-high frequency (UHF) electromagnetic (EM) signals generated by the partial discharge (PD) process of high-voltage equipment are now widely used in PD detection. The computation of EM propagation generated by a local discharge source using a uniformly hardwiring source can hardly reveal the discharge characteristics. In this paper, a method of near-field to far-field transformation is proposed to realize the study of the propagation characteristics of the PD signal. A short gap discharge model is established to get the near-field electromagnetics and the proposed method is validated by comparing the directly calculated results with the results of the near-field source. In the end, a model of switchgear is employed to study the propagation characteristics of the EM signal based on the proposed method. Via numerical calculation, the influence of the equipment in the switchgear on the propagation of the discharge EM is studied. It is found that the direction of the discharge source has a significant effect on the distribution of the electric field, which indicates that the discharge source cannot be simplified to a uniformly hardwiring source. In addition, it is also obtained that the amplitude of the electric field shows the same trend with the growth of the discharge channel, which gives a method for evaluating the development of the PD. Particularly, the near-field to far-field transformation can provide an effective method for studying the propagation of discharge EM waves in large-scale equipment.
Evaluation of the Spot Shape on the Target for Flat Heliostats
Authors: Jafrancesco David , Fontani Daniela , Francini Franco , Sansoni Paola
Published: June 2018

The aim of this study is to evaluate the changes of the spot shape on the target in dependence of the variations of size and faceting of a flat heliostat or an array of heliostats. The flat heliostat, or a flat heliostat array, is a layout common for Concentation Solar Power (CSP) plants. The spot shape is evaluated by means of a numerical integration of an appropriate function; in order to confirm the results, both an analysis based on the Lagrange invariance and some simulations are performed. The first one validates the power density value in the central part of the spot, while the simulations assess the spot shape, which in its central part differs less than 3% from the calculated result. The utilized numerical method does not require specialized software or complex calculation models; it determines an accurate spot shape but cannot take into account shading and blocking phenomena.
Jatropha curcas, L. Pruning Residues for Energy: Characteristics of an Untapped By-Product
Authors: Pari Luigi , Suardi Alessandro , Longo Leonardo , Carnevale Monica , Gallucci Francesco
Published: June 2018

Jatropha (Jatropha curcas, L.) is an energy crop mainly cultivated for the oil-seed, and the oil is usually used as bio-fuel. However, few studies have reported information about the utilization of the wood as a fuel for boiler heating systems. With 2500 jatropha trees per hectare, it is possible to produce about 3 t·ha−1·y−1 of woody biomass from pruning. In addition, jatropha trees are commonly cut down to a height of 45 cm once every 10 years, with a production of 80 t·ha−1 of dry matter of woody biomass. The use of this biomass has not yet been investigated. During the European project JatroMed, woody biomass from jatropha pruning was collected in Morocco. Chemical and physical characteristics of the wood were conducted according to UNI EN ISO standards. The following jatropha wood characteristics have been analyzed: Moisture and ash contents, the ash melting point, heating value, and concentrations of C, H, N, and S. This research focused on the evaluation of the potential use of jatropha pruning for energy production, and the results represent critical data that is useful for future studies and business potential.
Gain Scheduled Torque Compensation of PMSG-Based Wind Turbine for Frequency Regulation in an Isolated Grid
Authors: Wang Haixin , Yang Junyou , Chen Zhe , Ge Weichun , Hu Shiyan , Ma Yiming , Li Yunlu , Zhang Guanfeng , Yang Lijian
Published: June 2018

Frequency stability in an isolated grid can be easily impacted by sudden load or wind speed changes. Many frequency regulation techniques are utilized to solve this problem. However, there are only few studies designing torque compensation controllers based on power performances in different Speed Parts. It is a major challenge for a wind turbine generator (WTG) to achieve the satisfactory compensation performance in different Speed Parts. To tackle this challenge, this paper proposes a gain scheduled torque compensation strategy for permanent magnet synchronous generator (PMSG) based wind turbines. Our main idea is to improve the anti-disturbance ability for frequency regulation by compensating torque based on WTG speed Parts. To achieve higher power reserve in each Speed Part, an enhanced deloading method of WTG is proposed. We develop a new small-signal dynamic model through analyzing the steady-state performances of deloaded WTG in the whole range of wind speed. Subsequently, H∞ theory is leveraged in designing the gain scheduled torque compensation controller to effectively suppress frequency fluctuation. Moreover, since torque compensation brings about untimely power adjustment in over-rated wind speed condition, the conventional speed reference of pitch control system is improved. Our simulation and experimental results demonstrate that the proposed strategy can significantly improve frequency stability and smoothen power fluctuation resulting from wind speed variations. The minimum of frequency deviation with the proposed strategy is improved by up to 0.16 Hz at over-rated wind speed. Our technique can also improve anti-disturbance ability in frequency domain and achieve power balance.
Combining Grey Model and Self-Adapting Intelligent Grey Model with Genetic Algorithm and Annual Share Changes in Natural Gas Demand Forecasting
Authors: Fan Guo-Feng , Wang An , Hong Wei-Chiang
Published: June 2018

Along with the high growth rate of economy and fast increasing air pollution, clean energy, such as the natural gas, has played an important role in preventing the environment from discharge of greenhouse gases and harmful substances in China. It is very important to accurately forecast the demand of natural gas in China is for the government to formulate energy policies. This paper firstly proposes a combined forecasting model, name GM-S-SIGM-GA model, to forecast the demand of natural gas in China from 2011 to 2017, by constructing the grey model (GM(1,1)) and the self-adapting intelligent grey model (SIGM), respectively; then, it employs a genetic algorithm to determine the combined weight coefficients between these two models. Finally, using the tendency index (the annual changes of the share of natural gas consumption from the total energy consumption), which completely reveal the annual natural gas consumption share among the market, to successfully adjust the fluctuated changes for each data period. The natural gas demand data from 2002 to 2010 in China are used to model the proposed GM-S-SIGM-GA model, and the data from 2011 to 2017 are used to evaluate the forecasting accuracy. The experimental results demonstrate that the proposed GM-S-SIGM-GA model is superior to other single forecasting models in terms of the mean absolute percentage error (MAPE; 4.48%), the root mean square error (RMSE; 11.59), and the mean absolute error (MAE; 8.41), respectively, and the forecasting performances also receive the statistical significance under 97.5% and 95% confident levels, respectively.
An Experimental Study of the Solar Collection Performance of Liquid-Type Solar Collectors under Various Weather Conditions
Authors: Choi Youngjin
Published: June 2018

To design and use a solar heating system properly, it is very important to evaluate the performance of its solar collector. Because the solar collection efficiency of a solar collector depends on the amount of solar radiation, the conditions of the heating medium (e.g., flow rate and inlet temperature), and the outside air temperature, it is necessary to consider the performance of the solar collector in actual weather conditions that are likely to prevail when using the system for heating and hot water. In the present study, test equipment was manufactured to measure the efficiency of solar collectors. Using this equipment, the heating characteristics of seven types of solar collectors were measured. In addition, the amount of solar heat collected per unit area was calculated for seven regions in Japan to compare the solar collection performance for different weather conditions, such as the outside temperature and the amount of solar radiation. In addition, the amount of solar heat collected per unit area was calculated for seven regions in Japan to compare the solar collection performance for different weather conditions, such as outside temperature and the amount of solar radiation. The results show that the solar collection performance is climate dependent and that it is necessary to select a suitable collector for each region through a preliminary examination of the solar collection in the initial design stage.
Numerical Study on the Dynamic Behavior of a Francis Turbine Runner Model with a Crack
Authors: Zhang Ming , Valentin David , Valero Carme , Egusquiza Mònica , Zhao Weiqiang
Published: June 2018

Crack appearance in the blade is the most common type of fatigue damage in Francis turbines. However, it is sometimes difficult to detect cracks in time using the current monitoring system, even when they are very large. To better monitor cracks, it is imperative to research the effect of a crack on the dynamic behavior of a Francis turbine. In this paper, the dynamic behavior of a Francis turbine runner model with a crack has been researched numerically. The intact numerical model was first validated by the experimental data available. Then, a crack was created at the intersection line between one blade and the crown. The change in dynamic behavior with increasing crack length has been investigated. Crack-induced vibration localization theory has been used to explain the dynamic behavior changes due to the crack. Modal analysis showed that the adopted theory could basically explain the modal behavior change due to the crack. The FFT results of the modal shapes and the localization factors (LF) has been used to explain the forced response changes due to the crack. Based on the above analysis, the challenge of crack monitoring has been analyzed. This research provides some references for more advanced monitoring technologies.
Interleaved High Step-Up DC-DC Converter Based on Voltage Multiplier Cell and Voltage-Stacking Techniques for Renewable Energy Applications
Authors: Chen Shin-Ju , Yang Sung-Pei , Huang Chao-Ming , Chou Huann-Ming , Shen Meng-Jie
Published: June 2018

A novel interleaved high step-up DC-DC converter based on voltage multiplier cell and voltage-stacking techniques is proposed for the power conversion in renewable energy power systems. The circuit configuration incorporates an input-parallel output-series boost converter with coupled inductors, clamp circuits and a voltage multiplier cell stacking on the output side to extend the voltage gain. The converter achieves high voltage conversion ratio without working at extreme large duty ratio. The voltage stresses on the power switches are significantly lower than the output voltage. As a result, the low-voltage-rated metal-oxide-semiconductor field-effect transistors (MOSFETs) can be employed to reduce the conduction losses and higher conversion efficiency can be expected. The interleaved operation reduces the input current ripple. The leakage inductances of the coupled inductors act on mitigating the diode reverse recovery problem. The operating principle, steady-state analysis and design guidelines of the proposed converter are presented in detail. Finally, a 1-kW prototype with 28-V input and 380-V output voltages was implemented and tested. The experimental results are presented to validate the performance of the proposed converter.
Game Theoretic Spectrum Allocation in Femtocell Networks for Smart Electric Distribution Grids
Authors: Mohammadi Ali , Dehghani Mohammad Javad , Ghazizadeh Elham
Published: June 2018

Ever growing penetration of the behind-the-meter technologies is changing the electricity consumption profiles of end-users. Intelligent coordination of these emerging technologies through a robust communication infrastructure enables their seamless integration with electric utilities’ operation. In this context, an efficient and reliable communication infrastructure plays a pivotal role in enabling optimal integration of emerging resources. In this paper, we propose a game-theory based method to enhance efficiency of the underlying communication network. Specifically, we focus on Femtocell communication technology which is one the promising options for improving poor indoor communication coverage. The major drawback for using femtocell communication technology is cross-layer interference of femto users (FUs) and macro users (MUs) which adversely impact network performance. In this paper, we propose a novel approach for sharing spectrum in a cognitive radio system with FUs and MUs as primary and secondary users, respectively. The underlying problem is formulated as Stackelberg game that is joined with a convex optimization problem. In this study, MUs and FUs are assumed to be selfish, rational and motivated to achieve maximum utility function, while MUs are competing to obtain maximum bandwidth. Finally, we present a closed form solution for the proposed approach which obtains a unique Nash Equilibrium and prioritizes the access of MUs to femto-base stations. Simulation results provide proof of concept and verify the effectiveness of our mathematical modeling.