bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation Methodology on Trajectory of Inbound Single Ship Using Similarity Measurement Between Planar Clouds
Authors: Fang C , Ren H , Jin Y , Dong C
Published: July 2019

In order to evaluate the ship trajectory more reasonable based on the quantitative information. This paper presents a new approach to evaluate the inward-port single ship trajectory quantitatively based on ship-handling simulator. First, a ship tracking points generating algorithm is proposed to generate sufficient tracking points in order to address the issue that the sample information is not enough on the ship simulator. Second, three reference tracking belts are established based on the sample data and cloud drop contribution degrees for the scenario that the collected samples information are enough. Finally, a quantitative score evaluation method that combines the qualitative information and the quantitative information is proposed, the similarity measurement results verify that the MES algorithm is more reasonable, the evaluation results of inward-port single ship trajectory illustrative that the proposed method is effective when applied to quantitative evaluation problems.
Experimental Investigation into the Effects of Reduced Vertical Centre of Gravity of an Articulated Concrete Mattress in Current View
Authors: Neville A , McLaren R , Weber J , Chin C , Binns J , Taylor A
Published: July 2019

An articulated concrete mattress model has been utilised to investigate the effects of reduced vertical centre of gravity on the stability of a 400 series block. Experimental testing was conducted at the AMC CWC, Beauty Point. To determine the effects that a reduced centre of gravity has on stability, the 3 by 3 articulated concrete mattress model was subject to pure uniform current flow. The subsequent forces were analysed with a six degree of freedom underwater force sensor. In order to gain a range of real world scenarios, the experimental model was tested at six flow angles ranging from -15 degrees through to 60 degrees, at 15 degree increments. Additionally, five fluid velocities starting at 0.6 m/s through to 1.4 m/s, at 0.2 m/s increments were investigated. These results explain how the inversion of a 400 series block increases its hydrodynamic coefficients and subsequently decreases its stability performance in current flow. Ultimately, this study provides experimental information for the installation of 400 series articulated concrete mattresses in the inverted orientation.
Model Predictive Control of an AUV Using De-Coupled Approach
Authors: Prasad M P R
Published: July 2019

This paper considers the decoupled dynamics and control of an Autonomous Underwater Vehicle (AUV). The decoupled model consists of speed, steering and depth subsystems. Generally AUV model is unstable and nonlinear. The central theme of this paper is the development of model predictive control (MPC) for underwater robotic vehicle for ocean survey applications. The proposed MPC for decoupled structure can have simple implementation. Simulation results have been presented which confirm satisfactory performance. Decoupled approach is well suitable for applying control.
Pressure Re-Impulse Diagram of the FLNG Tanks Under Sloshing Loads
Authors: Lee S E , Paik J K
Published: July 2019

Sloshing impact loads can cause severe structural damage to cargo tanks in liquefied natural gas floating production storage offloading units (LNG-FPSOs or FLNGs). Studies of sloshing can be classified into two types, namely, hydrodynamics-related and structural mechanics-related studies. This study is a sequel to the authors’ previous studies (Paik et al. 2015; Lee et al. 2015), but is more related to issues of structural mechanics. In this study, a new method for probabilistic sloshing assessment, which has been previously developed by the authors, is briefly explained. The nonlinear impact structural response characteristics under sloshing impact loads are examined by a nonlinear finite element ANSYS/LS-DYNA method. An iso-damage curve, representing a pressure-impulse diagram, is derived for the self-supporting prismatic-shape IMO B type LNG cargo containment system of a hypothetical FLNG. The insights
developed from this work can be useful for the damage-tolerant design of cargo tanks in FLNGs.
Frictional Drag Reduction: Review and Numerical Simulation of Microbubble Drag Reduction in a Channel Flow
Authors: Sindagi S , Vijayakumar R , Saxena B K
Published: July 2019

The reduction of ship’s resistance is one of the most effective way to reduce emissions, operating costs and to improve EEDI. It is reported that, for slow moving vessels, the frictional drag accounts for as much as 80% of the total drag, thus there is a strong demand for the reduction in the frictional drag. The use of air as a lubricant, known as Micro Bubble Drag Reduction, to reduce that frictional drag is an active research topic. The main focus of authors is to present the current scenario of research carried out worldwide along with numerical simulation of air injection in a rectangular channel. Latest developments in this field suggests that, there is a potential reduction of 80% & 30% reduction in frictional drag in case of flat plates and ships respectively. Review suggests that, MBDR depends on Gas or Air Diffusion which depends on, Bubble size distributions and coalescence and surface tension of liquid, which in turn depends on salinity of water, void fraction, location of injection points, depth of water in which bubbles are injected. Authors are of opinion that, Microbubbles affect the performance of Propeller, which in turn decides net savings in power considering power required to inject Microbubbles. Moreover, 3D numerical investigations into frictional drag reduction by microbubbles were carried out in Star CCM+ on a channel for different flow velocities, different void fraction and for different cross sections of flow at the injection point. This study is the first of its kind in which, variation of coefficient of friction both in longitudinal as well as spanwise direction were studied along with actual localised variation of void fraction at these points. From the study, it is concluded that, since it is a channel flow and as the flow is restricted in confined region, effect of air injection is limited to smaller area in spanwise direction as bubbles were not escaping in spanwise direction.
Effect of the Boundary Conditions on the Dynamic Behaviours of Subsea Free-Spanning Pipelines
Authors: Li T T , An C , Duan M L , Huang H , Liang W
Published: July 2019

This paper establishes a fast and accurate solution of the dynamic behaviours of subsea free-spanning pipelines under four different boundary conditions, based on GITT - the generalised integral transform technique. The fluid-structure interaction model is proposed by combining a linear structural equation and a non-linear distributed wake oscillator model, which simulates the effect of external current acting on the pipeline. The eigenvalue problems for the cross-flow vibration of the free-spanning submarine pipeline conveying internal fluid for four different boundary conditions are examined. The solution method of the natural frequency based on GITT is proposed. The explicit analytical formulae for the cross-flow displacement of the pipeline free span are derived, and the mode shapes and dynamic behaviours of the pipeline free span are discussed with different boundary conditions. The methodology and results in this paper can also expand to solving even more complicated boundary-value problems.
Viscosity in Seakeeping
Authors: Pawłowski M
Published: July 2019

Application of strip theory for the prediction of ship motions in waves relies on sectional hydrodynamic coefficients; i.e. the added mass and damping coefficients. These coefficients apply to linearised problems and are normally computed for inviscid fluids. It is possible to account for viscosity but this cannot be done by the RANS equations, as in linear problems there is no room for turbulence. The hydrodynamic coefficients can include the effect of viscosity but this can be done rightly through the classic Navier–Stokes equations for laminar (non-turbulent) flows. For solving these equations commercial RANS software can be used, assuming no Reynolds stresses.
Virtual Hull Monitoring: Continuous Fatigue Assessment Without Additional Instrumentation - Technical Note
Authors: Thompson I M
Published: July 2019

Technical Note - A novel technique to monitor hull stresses using data currently collected on most ships is explored. This technique, referred to herein as virtual hull monitoring, uses global position signals, measured or numerically-modelled wave data, and a database of calculated stress transfer functions. This enables monitoring of short-term stress states and corresponding fatigue damage accumulation for many structural locations, either onboard or at a central location, for an entire fleet. The components, benefits, and limitations of this proposed technique are discussed. Wave buoy and strain gauge measurements from a full-scale naval vessel trial are used in comparisons with hindcast wave data and the calculated stress spectra for one structural location. Close agreement between the wave data sources and corresponding stress spectra warrants further examination of virtual hull monitoring.
Reinforcement of Ageing Ship Structures
Authors: Chichì D , Garbatov Y
Published: July 2019

The objective of the present study is to investigate the possibility to recover the ultimate strength of a rectangular steel plate with a manhole shape opening subjected to a uniaxial compressive load and non-uniform corrosion degradation reinforced by additional stiffeners. Finite element analyses have been carried out to verify the possible design solutions. A total of four finite element models are generated, including 63 sub-structured models. The non-uniform corrosion has been generated by the Monte Carlo simulation. The reinforcement process covers three scenarios that include mounting of two longitudinal stiffeners, two longitudinal and two transverse stiffeners and the flange on the opening. The positioning of the stiffeners has also been studied. A total of 10 cases has been selected and tested for the numerical experiment. Three different assessments have been performed to evaluate the ultimate strength, weight and cost. Two additional studies on the effect of the plate thickness and slenderness have been also carried out.
Effects of Marine Condition on the Speed and Fuel Consumption of a Fully-Loaded VLCC
Authors: Hakimzadeh H , Badri M A , Torabi Azad M , Azarsina F , Ezam M
Published: July 2019

Minimizing fuel consumption is a priority for ship-owners seeking to reduce their vessel costs due to sea conditions. One of the most reliable methods used to estimate fuel consumption is to identify field investigations for future voyages. The VLCC Salina was used based on daily field data collected over a proper period and year of 2014 was identified as a period of optimal performance after its periodic dry dock repair. According to verified results for Beaufort scales of 2, 3 and 4, the vessel exhibited an average speed loss of 2.2% due to wind and wave effects for a Froude number of 0.15 while its greatest speed loss was observed at angles of 30‒60° relative to its longitudinal axis. The results were finally used to develop a methodology for estimating fuel consumption of Salina and 3 other sister-ships, during future voyages, in the fleet of the National Iranian tanker company.
Performance Prediction of a 112m Wave-Piercing Catamaran
Authors: Kay E , Lavroff J , Davis M R
Published: July 2019

The prediction of power required to propel a high-speed catamaran involves the hydrodynamic interactions between the hull surface and the surrounding fluid that may be difficult to compute numerically. In this study model-scale experiments are used as a basis for comparison to full-scale sea trials data measured on a 112m Incat wave-piercing catamaran to predict the full-scale powering requirements from model-scale testing. By completing water jet shaft power measurements on an Incat vessel during sea trials, comparison of these results was made to model-scale test results to provide good correlation. The work demonstrates that the International Towing Tank Conference (ITTC) extrapolation techniques used provide a good basis for extrapolating the data from model-scale to full-scale to predict the power requirements for the full-scale catamaran vessel operating at high Froude Number with water jet propulsion. This provides a useful tool for future designers and researchers for determining the power requirements of a catamaran vessel through model tests.
An Optimized Energy-Efficient Path Following Algorithm for Underactuated Marine Surface Ship Model
Authors: Xu Haitong , Guedes Soares C
Published: July 2019

An optimized path following guidance law is proposed for path-following of an underactuated surface ship. The main purpose of the proposed guidance law is to make a marine vessel travel with more energy efficiency. A combined feedback and feedforward controller is used for the heading control. The feedforward term is designed based on the well-known Nomoto model, whose parameters are estimated using least-square support vector regression. In order to achieve optimal operation of a marine vessel, a global optimization algorithm is employed to search the regularization
factors, which are the trade-off between the total cross-track errors and total control energy. The simulation studies are carried out to demonstrate the performance of the proposed guidance law. The proposed method is an effective and practical guidance law and provide an optimal option for marine navigator.
Optimization of Pyrrole Electropolymerization on a Steel Gauze Electrode Using the Cyclic Voltammetry Method
Authors: Sukmawardani Yulia , Ihsanawati  , Buchari Buchari
Published: July 2019

Study on pyrrole electropolymerization is the preliminary step in synthesizing polypyrrole membranes, which can be used for various purposes in biosensor. In this work, electropolymerization process and electrochemical analysis of polypyrrole as an electroactive polymer have been studied by cyclic voltammetry. Pyrrole was electropolymerized to form polypyrrole in an aqueous potassium chloride solution at different pHs using phosphate buffer. The results showed that a potential range of 0-1200 mV is suitable for polypyrrole electropolymerization using the Ag|AgCl electrode as the reference. The formation of polypyrrole is stable at a scan rate of 100 mV/s. In addition, the optimized pyrrole electropolymerization was obtained using 0.1 M pyrrole and phosphate buffer at pH of 2-6. Taken together, this study can be used as a reference for the synthesis of other conducting polymers.
The Synthesis of Polyethersulfone (PES) Derivatives for the Immobilization of Lipase Enzyme
Authors: Rahmahwati Nurlaela , Wahyuningrum Deana , Alni Anita
Published: July 2019

Nowadays the development of biodiesel production as an alternative renewable energy became crucial. The reusability of enzymes as biocatalysts in biodiesel production has limitations and can be improved by the immobilization process onto the appropriate solid support, such as polyethersulfone (PES). Polyethersulfone has been synthesized utilizing microwave-assisted reaction method (400 W, 170 °C, 60 minutes). Nitration reaction of PES was performed by refluxing the synthesized PES with the mixtures of H2SO4 (0 °C, ± 30 minutes) and HNO3 (25 °C, 4 hours). The –NO2 groups of the synthesized PES-NO2 was subsequently reduced to be PES-NH2 using SnCl2.2H2O as reducing agent by reflux method (60 °C, ± 3 hours). The structure of PES and its derivatives was confirmed by FTIR and 1H-NMR. Candida antarctica lipase was successfully immobilized onto the synthesized PES and its derivatives, which were confirmed by its FTIR spectra and its activity tests of the supernatants in hydrolyzing p-nitrophenol palmitate (pNPP) into p-nitrophenol (pNP). The results showed that the conversion percentage of pNPP to become pNP were 20.6% (free enzyme), 18.9% (PES-enzyme), and 3.7% (PES-NH2-enzyme). The decrease in the supernatant enzyme activity showed that the enzyme has been successfully immobilized through physical adsorption onto the synthesized polymers.
Influence of pH and Concentration of Ionic Strength Adjuster (ISA) on the Performance of Nd(III) Ion Selective Electrodewith 4-Sebacoylbis(1-Phenyl-3-Methyl-5-Pyrazolone)(H2SbBP) as Ionophores
Authors: Sosidi Husain , Noviandri Indra , Buchari Buchari
Published: July 2019

4-Sebacoylbis (1-phenyl-3-methyl-5-pyrazolone) (H2SbBP) ligand has been successfully synthesized, characterized and used as ionophores in Nd (III) selective electrode, using polytetrafluoroethylene (PTFE) membranous as a support. Prior to use the PTFE membrane soaked ionophores 1.5% w/v in chloroform for 24 hours. The performance of electrode studied by seeing the influence of pH and concentration of KNO3as a buffer solution ionic strength. Variations in pH of the solution was set at pH ranges between 1 to 10 using a solution of HCl and NaOH, while KNO3concentration varied between 10-4to 10-1M. Nd3+concentration range is between 10-6up to 10-2M. The best electrode performance was obtained at pH 5 and 10-2M KNO3concentration with a sensitivity of (18.5 ± 0.2) mV/decade and its response time less than 25 seconds.
Preparation and Characterization of Poly(Methyl Methacrylate) (PMMA) Fibers by Electrospinning
Authors: Suryandari Ervin Tri , Zulfikar Muhammad Ali , Mukti Rino R. , Nasir Muhamad
Published: July 2019

Fibers are materials with advantageous properties such as lightweight material properties, has small pore size, and has high surface area, porosity,and permeability. An easy and simple method to prepare fibers is electrospinning. Using this method poly(methyl methacrylate) (PMMA) fibers were prepared. Several parameters include polymer concentration, solution flow rate, the distance of the nozzle tip to the collector, and the applied voltage were investigated to control the morphology, structure, and diameter of PMMA fibers. The Optimal electrospinning conditions for PMMA fibers production were a PMMA concentration is 8% (w/v), a power supply voltage is 20 kV, a distance of the tip of the nozzle to the ground collector is 15 cm, and a flow rate is 0.004 mL/min. The diameter distribution and morphology of the fibers were determined and characterized by Optical Microscopy and Scanning Electron Microscope (SEM), which showed that the produced fiber had an average diameter of 1.4925 µm, the contact angle of fiber PMMA is 125.307o and the spreading time of fibers PMMA is about 360 minutes
Synthesis of Composite Zn2SnO4/SnO2 as Photocatalyst Materials by Means of Sonochemical Treatment and Its Electronic Structure
Authors: Prijamboedi Bambang , El Aisnada An Niza , Kuswantoro Wahyu Orphan
Published: July 2019

Metal oxide semiconducting compounds have potential application as photocatalyst materials to decompose many types of dyes and pollutants in the water. Zn2SnO4 and SnO2 are semiconducting materials that have photocatalytic properties and the properties of those two semiconducting materials in the composite form have been studied. Metal oxide compounds of Zn2SnO4 and SnO2 have been prepared through sonochemical methods using ZnCl2 and SnCl4.5H2O as precursors. After sonication and heat treatment at 1000 °C, we could obtain Zn2SnO4 and SnO2 compound in the sample as confirmed by x-ray diffraction measurement. The volume fraction of Zn2SnO4 and SnO2 phases in the sample were found to be at 60 % and 40 %, respectively. The absorption spectra revealed that the band gap of the composite materials is 3.7 eV. This material could degrade all of the methylene blue with concentration of 6.0 x 10-6 M in 120 minutes. The band structure calculation revealed that the comparable band gap values are found for Zn2SnO4 and SnO2 compounds. However, the absorption edges for those compounds are slightly different, with absorption edge at 3.2 eV for SnO2 and 3.6 eV for Zn2SnO4, respectively.
Modelling effect of valuable resources on franchise outlet performance: Dynamic sensing capability as mediator
Authors: Zimuto Jilson , Maritz Rachel
Published: July 2019

Background: Competitive advantage and superior firm performance depend on resources and dynamic capabilities.Aim: This study aims to provide insight into the franchising industry where research on the value-dynamic sensing capability-performance relationship as part of the resource-based theory (RBT) seems to be novel. Drawing on the RBT, this study examines how valuable resources and dynamic sensing capability impact franchise outlet performance.Setting: Based on a cross-sectional design, a sample of 224 South African franchise outlet managers and owner-operators in the fast food and retailing categories was surveyed.Methods: Hypotheses were tested using a single-level structural equation model for value, dynamic sensing capability and performance.Results: The results contribute to research on RBT in the context of franchises by providing support for the assumption that firm resources and capabilities improve performance.Conclusion: The findings are expected to provide a strong base from which franchise managers and owner-operators can strategise for competitive advantage in an emerging economy like South Africa.
Bulk-fill versus conventional composite: A comparative analysis on degree of conversion
Authors: Jassé Fernanda Ferreira de Albuquerque , Barud Hélida Gomes de Oliveira , Boaventura Juliana Maria Capelozza , Alencar Cristiane de Melo , Gatti Alexandre , Campos Edson Alves de
Published: July 2019

Aim: This study aimed to determine the degree of conversion (DC) of two resin-based composites: a conventional nanohybrid composite and a bulk-fill flowable composite (SureFil® SDR™ flow). Materials and Methods: DC was evaluated at 1-, 2-, 3-, and 4-mm depths at varying irradiation times (20 and 40 s) by Fourier-transform infrared spectroscopy. Disc-shaped specimens of varying depths were prepared and photoactivated with a third-generation light-emitting diode light-curing unit. The specimens were stored for 24 h in the dark at ambient temperature and pulverized into a fine powder which was mixed with potassium bromide. After homogenization, the mixture pressed to form a pellet. All pellets were evaluated by an infrared spectrometer equipped with a triglycine sulfate detector using diffuse reflectance. The percentage of monomer conversion was determined from the ratio of the absorbance intensities of the aliphatic carbon–carbon double bonds (C = C) and the internal standard before and after the curing of the composite, represented by the aromatic carbon–carbon single bonds (C-C). Results: The DC data for the bulk-fill resin showed no significant difference (P > 0.05) for different irradiation depths, whereas for the conventional nanohybrid resins, statistical analyses revealed a significant result of the variables time and depth as well as the interaction between them. Conclusions: The results indicated that SDR™ achieves a 4-mm depth of cure with both 20- and 40-s light exposures.
Comparison of miller’s classification of gingival recession defects with mahajan’s classification of gingival recession defect: A reliability study
Authors: Mahajan Ajay , Asi Kanwarjit Singh , Rayast Deepa , Negi Mayum
Published: July 2019

Background: Gingival recession is a common periodontal problem encountered in most populations. A number of classification systems are available to classify gingival recession defects (GRDs), but there has been a lack of consensus among the clinicians regarding the choice of classification system to classify GRDs. Recently, Miller’s classification has been criticized owing to its inherent limitations. Mahajan’s classification was proposed to eliminate the drawbacks of Miller’s classification system. To the best of our knowledge, there has been no study testing or comparing the reliability of Miller’s classification; therefore, the present study was done to compare the reliability of Miller’s classification with Mahajan’s classification. Materials and Methods: The sites selected for the study were classified for GRD according to either Miller’s classification or Mahajan’s classification by the two groups of four examiners. All the examiners were calibrated for the two classification systems and classified the selected sites accordingly. Kappa statistics was performed to analyze the intra- and interrater agreement among the four examiners. Results: A total of 609 gingival recession sites in 91 patients (49 males and 42 females) were classified. At the end of the study, Mahajan’s classification had a higher intrarater (κ = 0.93–0.83) and interrater reliability (κ = 0.93) compared to Miller’s classification for GRD for both intrarater (κ = 0.57–0.68) and interrater observations (κ = 0.66), respectively. Conclusions: Miller’s classification system was less reliable than Mahajan’s classification system.
Not All Errors Are Created Equal: Influence of User Characteristics on Measurement Errors of Consumer Wearable Devices for Sleep Tracking
Authors: Liang Zilu , Alberto Chapa Martell Mario
Published: July 2019

Consumer sleep tracking devices are known to be inaccurate, but there is a lack of understanding of how user characteristics may affect the accuracy of these devices. This study aims to examine the effect of age, gender, subjective sleep quality, sleep hygiene and sleep structure on the accuracy of two consumer sleep trackers, i.e. Fitbit Charge 2 and Neuroon. Sleep data were collected from 27 healthy participants using consumer devices and a medical device concurrently. Analysis found that age, sleep hygiene and sleep structure were significantly associated to the accuracy of consumer sleep trackers, whereas no association was found on gender and subjective sleep quality. Both consumer devices had improved accuracy on total sleep time and sleep efficiency for participants who had longer, deeper and less interrupted sleep. Our findings suggest that consumer devices may not be suited for young adults and for people with short and fragmented sleep.
Parental Leave for Residents at Programs Affiliated With the Top 50 Medical Schools
Authors: Gottenborg Emily , Rock Lindsay , Sheridan Alison
Published: July 2019

Background

Of the top 15 medical schools with affiliated graduate medical education (GME) programs, 8 offer paid parental leave, with an average duration of 6.6 weeks. It is not known how other GME programs approach parental leave.

Objective

We searched for the parental leave policies for residents in programs affiliated with the top 50 medical schools.

Methods

In 2019, we identified the top 50 medical schools designated by US News & World Report in the research and primary care categories (totaling 59 schools), and identified the associated GME programs. For each school, we accessed its website and searched for “GME Policies and Procedures” to find language related to maternity, paternity, or parental leave, or the Family Medical Leave Act. If unavailable, we e-mailed the GME office to identify the policy.

Results

Of 59 schools, 25 (42%) described paid parental leave policies with an average of 5.1 weeks paid leave; 11 of those (44%) offer ≤ 4 weeks paid parental leave. Twenty-five of 59 (42%) programs did not have paid parental leave, but 13 of these specify that residents can use sick or vacation time to pay for part of their parental leave. Finally, 13 of 59 (22%) offered state mandated partial paid leave. One school did not have any description of parental leave.

Conclusions

While paid parental leave for residents has been adopted by many of the GME programs affiliated with the top 50 medical schools, it is not yet a standard benefit offered to the majority of residents.
The effect of low density over the “roof of the world” Tibetan Plateau on the triggering of convection
Authors: Wang Yinjun , Xu Xiangde , Zhou Mingyu , Lenschow Donald H. , Guo Xueliang , Zhao Yang , Chen Bin
Published: July 2019

Abstract. We study the relationships between convective characteristics and air density over the Tibetan Plateau (TP) from the perspective of both climate statistics and large eddy simulation (LES). First, based on climate data, we found that there is stronger thermal turbulence and higher frequency of low cloud formation for the same surface relative humidity over the eastern and central TP compared with the eastern monsoon region of China. Second, we focus on the dynamical and thermal structure of the atmospheric boundary layer (ABL) with low air density. With the same surface heat flux, a decrease in air density enhances the buoyancy flux, which increases the ABL depth and moisture transport from the subcloud layer into the cloud layer. With the same low cloud cover for different air densities, the greater ABL depth for lower air density means that the average mixed-layer relative humidity with higher air density will be greater than that with low air density. Results from a subcloud convective velocity scaling scheme were compared with LES results, which indicated that the original fixed parameter values in this scheme may not adequate in case of lower relative humidity and weaker thermal turbulence in the subcloud layer.
Small Ice Particles at Slightly Supercooled Temperatures in Tropical Maritime Convection
Authors: Lloyd Gary , Choularton Thomas , Bower Keith , Crosier Jonathan , Gallagher Martin , Flynn Michael , Dorsey James , Liu Dantong , Taylor Jonathan W. , Schlenczek Oliver , Fugal Jacob , Borrmann Stephan , Cotton Richard , Field Paul , Blyth Alan
Published: July 2019

Abstract. In this paper we show that the origin of the ice phase in tropical cumulus clouds over the sea may occur by primary ice nucleation of small crystals at temperatures just between 0 and −5 °C. This was made possible through use of a holographic instrument able to image cloud particles at very high resolution and small size (6 µm). The environment in which the observations were conducted was notable for the presence of desert dust advected over the ocean from the Sahara. However, there is no laboratory evidence to suggest that these dust particles can act as ice nuclei at temperatures warmer than about −10 °C, the zone in which the first ice was observed in these clouds. The small ice particles were observed to grow rapidly by vapour diffusion, riming, and possibly through collisions with supercooled raindrops, causing these to freeze and potentially shatter. This in turn leads to the further production of secondary ice in these clouds. Hence, although the numbers of primary ice particles are small, they are very effective in initiating the rapid glaciation of the cloud, altering the dynamics and precipitation production processes.
Spatial and seasonal effects on the delayed ionospheric response to solar EUV changes
Authors: Schmölter Erik , Berdermann Jens , Jakowski Norbert , Jacobi Christoph
Published: July 2019

Abstract. This study correlates different ionospheric parameters with the integrated solar EUV radiation for an analysis of the delayed ionospheric response in order to confirm previous studies on the delay and to further specify variations of the delay. Several time series for correlation coefficients and delays are presented to characterize the trend of the delay from 2011 to 2013. The impact of the diurnal variations of ionospheric parameters in the analysis on hourly resolution for fixed locations are discussed and specified with calculations in different time scales and with comparison to solar and geomagnetic activity. An average delay for TEC of ≈ 18.7 hours and for foF2 of ≈ 18.6 hours is calculated at four European stations. Through comparison with the Australian region the difference between northern and southern hemisphere is analyzed and a seasonal variation of the delay between northern and southern hemisphere is calculated for TEC with ≈ 5 ± 0.7 hours and foF2 with ≈ 8 ± 0.8 hours. The latitudinal and longitudinal variability of the delay is analyzed for the European region and a decrease of the delay from ≈ 21.5 hours at 30° N to ≈ 19.0 hours at 70° N has been found. For winter months a roughly constant delay of ≈ 19.5 hours is calculated. In this study a North-South trend of the ionospheric delay during summer month has been observed with ≈ 0.06 hours per degree in latitude. The results based on solar and ionospheric data in hourly resolution and the analysis of the delayed ionospheric response to solar EUV show the seasonal and latitudinal variations. Results also indicate the dependence on the geomagnetic activity as well as on the 11-year solar cycle.
Description and basic evaluation of simulated mean state, internal variability, and climate sensitivity in MIROC6
Authors: Tatebe Hiroaki , Ogura Tomoo , Nitta Tomoko , Komuro Yoshiki , Ogochi Koji , Takemura Toshihiko , Sudo Kengo , Sekiguchi Miho , Abe Manabu , Saito Fuyuki , Chikira Minoru , Watanabe Shingo , Mori Masato , Hirota Nagio , Kawatani Yoshio , Mochizuki Takashi , Yoshimura Kei , Takata Kumiko , O'ishi Ryouta , Yamazaki Dai , Suzuki Tatsuo , Kurogi Masao , Kataoka Takahito , Watanabe Masahiro , Kimoto Masahide
Published: July 2019

Abstract. The sixth version of the Model for Interdisciplinary Research on Climate
(MIROC), called MIROC6, was cooperatively developed by a Japanese modeling
community. In the present paper, simulated mean climate, internal
climate variability, and climate sensitivity in MIROC6 are evaluated and
briefly summarized in comparison with the previous version of our climate
model (MIROC5) and observations. The results show that the overall
reproducibility of mean climate and internal climate variability in MIROC6
is better than that in MIROC5. The tropical climate systems (e.g.,
summertime precipitation in the western Pacific and the eastward-propagating
Madden–Julian oscillation) and the midlatitude atmospheric circulation
(e.g., the westerlies, the polar night jet, and troposphere–stratosphere
interactions) are significantly improved in MIROC6. These improvements can
be attributed to the newly implemented parameterization for shallow
convective processes and to the inclusion of the stratosphere. While there
are significant differences in climates and variabilities between the two
models, the effective climate sensitivity of 2.6 K remains the same because
the differences in radiative forcing and climate feedback tend to offset
each other. With an aim towards contributing to the sixth phase of the
Coupled Model Intercomparison Project, designated simulations tackling a
wide range of climate science issues, as well as seasonal to decadal climate
predictions and future climate projections, are currently ongoing using
MIROC6.
Cross-validating precipitation datasets in the Indus River basin
Authors: Baudouin Jean-Philippe , Herzog Michael , Petrie Cameron A.
Published: July 2019

Abstract. Large uncertainty remains about the amount of precipitation falling in the Indus River basin, particularly in the more mountainous northern part. While rain gauge measurements are often considered as a reference they are only punctual and subject to underestimation. Satellite observations and reanalysis output can improve our knowledge but validating their results is often difficult. In this study, we offer a cross-validation of 20 gridded datasets based on rain gauge, satellite and reanalysis, including the most recent and little studied APHRODITE-2, MERRA2, and ERA5. This original approach to cross-validation alternatively uses each dataset as a reference and interprets the result according to their dependency with the reference. Most interestingly, we found that reanalyses represent the daily variability as well as any observational datasets, particularly in winter. Therefore, we suggest that reanalyses offer better estimates than non-corrected rain gauge-based datasets where underestimation is problematic. Specifically, ERA5 has proven to be the most able reanalysis for representing the amounts of precipitation as well as its variability from daily to multi-annual scale. By contrast, satellite observations bring limited improvement at the basin scale. For the rain gauge-based datasets, APHRODITE has the finest representation of the precipitation variability, yet importantly it underestimates the actual amount. GPCC products are the only datasets that include a correction of the measurements but remain likely too small. These findings highlight the need for a systematic characterisation of the underestimation of rain gauge measurements.
Multi-decadal hydrologic change and variability in the Amazon River basin: understanding terrestrial water storage variations and drought characteristics
Authors: Chaudhari Suyog , Pokhrel Yadu , Moran Emilio , Miguez-Macho Gonzalo
Published: July 2019

Abstract. We investigate the interannual and interdecadal
hydrological changes in the Amazon River basin and its sub-basins during
the 1980–2015 period using GRACE satellite data and a physically based, 2 km
grid continental-scale hydrological model (LEAF-Hydro-Flood) that includes a
prognostic groundwater scheme and accounts for the effects of land use–land
cover (LULC) change. The analyses focus on the dominant mechanisms that
modulate terrestrial water storage (TWS) variations and droughts. We find
that (1) the model simulates the basin-averaged TWS variations remarkably
well; however, disagreements are observed in spatial patterns of temporal
trends, especially for the post-2008 period. (2) The 2010s is the driest
period since 1980, characterized by a major shift in the decadal mean compared
to the 2000s caused by increased drought frequency. (3) Long-term trends in TWS
suggest that the Amazon overall is getting wetter (1.13 mm yr−1), but its
southern and southeastern sub-basins are undergoing significant negative TWS
changes, caused primarily by intensified LULC changes. (4) Increasing
divergence between dry-season total water deficit and TWS release suggests a
strengthening dry season, especially in the southern and southeastern
sub-basins. (5) The sub-surface storage regulates the propagation of
meteorological droughts into hydrological droughts by strongly modulating
TWS release with respect to its storage preceding the drought condition. Our
simulations provide crucial insight into the importance of sub-surface storage
in alleviating surface water deficit across Amazon and open pathways for
improving prediction and mitigation of extreme droughts under changing
climate and increasing hydrologic alterations due to human activities (e.g.,
LULC change).
Exposure of properties to the 2018 Hurricane Florence flooding: an expanding bull's-eye perspective
Authors: Tedesco Marco , McAlpine Steven , Porter Jeremy
Published: July 2019

Abstract. Properly quantifying the potential exposure of property to damages associated with storm surges, extreme weather, and hurricanes is fundamental to developing frameworks that can be used to conceive and implement mitigation plans as well as support urban development that accounts for such events. In this study, we aim at quantifying what was the total value and area of properties exposed to the flooding associated with Hurricane Florence. To this aim, we first generate a map of the maximum flood extent from the combination of the extent produced by FEMA and by means of spaceborne radar remote sensing. Such map is, then, used for estimating the value and area of properties exposed to flooding and the distance of such properties from permanent water bodies. Lastly, we study and quantify how the urban development over the past years and decades over the regions flooded by Hurricane Florence might have impacted the exposure of properties and population to present-day storms and floods, to account what colleagues are starting to address as the “expanding bull’s-eye effect” in which ‘‘targets” of geophysical hazards, such as people and their built environments, are enlarging as populations grow and spread. Our results indicate that the total value of property exposed was $52B, with this value increasing from ~ $10B (2018 USD) from the beginning of the past century because of the expansion of number of properties. We also found that, despite the slowing of property construction in the decade before Florence, much new construction was in proximity to permanent water bodies, increasing exposure to flooding. Ultimately, the results of this paper provide a tool for the understanding of the approaching reckoning that must take place between our continued development in coastal areas and the flooding of those areas, which is estimated to increase because of projected increasing sea level rise, storm surges and strength of storms.
Optimal relationship between power and design driving loads for wind turbine rotors using 1D models
Authors: Loenbaek Kenneth , Bak Christian , Madsen Jens I. , Dam Bjarke
Published: July 2019

Abstract. We investigate the optimal relationship between the aerodynamic power, thrust loading, and size of a wind turbine rotor when its design is constrained by a static aerodynamic load. Based on 1D-axial momentum theory, the captured power P~ for a uniformly loaded rotor can be expressed in terms of the rotor radius R and the rotor thrust coefficient CT. Common types of static Design Driving Load Constraints (DDLC), e.g. limits on permissible root-bending moment or tip deflection, may be generalized into a form that also depends on CT and R. Using these relationships to maximize P~ subject to a DDLC, shows that operating the rotor at the Betz limit (maximum CP) does not lead to the highest power capture. Rather, it is possible to improve performance with a larger rotor radius and lower CT without violating the DDLC. As an example, a rotor design driven by a tip-deflection constraints, may achieve 1.9 % extra power capture P~ compared to the baseline (Betz limit) rotor. The method is extended for optimization of rotors with respect to Annual Energy Production (AEP), where the thrust characteristics CT(V) needs to be determined together with R. This results in much higher relative potential for improvements, since the constraint limit can be met over a larger range of wind speeds. For example, a relative gain in AEP of +5.7 % is possible for a rotor design constrained by tip deflections compared with a rotor designed for optimal CP. The optimal solution for AEP leads to a thrust curve with three distinct operational regimes and so called thrust-clipping.
Servant Leadership Impact on Organizational Performance: The Mediating Role of Employee Engagement
Authors: Alafeshat Rawan , Aboud Farida
Published: July 2019

The current study, which purposed to examine the mediating role of Employee Engagement (EE) in the relationship of Servant Leadership (SL) with the Organizational Performance (OP), was carried out in Jordan. The researchers distributed a questionnaire to 277 participants working in the private airline sector. The study’s findings showed that SL was positively linked with Employee Satisfaction (ES) and Employee Retention (ER) as indicators for OP. Finally; the findings indicated that EE partially mediates the relationships of SL with employee satisfaction and employee retention. The current research is the first empirical study of the airline sector in Jordan. It is also the first to focus on EE as a mediator of the effect of SL and employee retention using Structural Equation Modeling (SEM) for analyzing the data collected from employees working in the airline sector.
Influence of Compensation and Organizational Culture on Employee Performance: A Study on IT Firms of Dhaka, Bangladesh
Authors: Haque Afdalin Bin , Mahmud Arif Al , Hossain Adnan
Published: July 2019

This paper aims to investigate the influence of Employee Compensation inclusive of Salary, Rewards and Incentives, Indirect Compensation and also Organizational Culture on the employee performance of the IT firms based on Dhaka, Bangladesh. A total of 204 employees of different IT firms of Dhaka were randomly selected as sample of the study responding to a structured questionnaire. The study incorporated Pearson Correlation and Multiple Regression analysis to analyze the data. The results exhibit the relationship and also demonstrate the impact of total compensation of employees and organizational culture on employee performance. The core findings of this study will benefit the user especially from the IT sector to identify the factors that increase the performance level of any IT personnel as the cumulative employee performance is the organization’s performance. The study is to be the first to explore the impact of Compensation and Organizational Culture on Employee performance in urban context of Bangladesh.
Pre-operative Diagnosis of Scar Endometriosis by Aspiration Cytology
Authors: Handa Uma , Mundi Irneet , Mohan Harsh
Published: July 2019

Purpose

Endometriosis is a fairly common disease found in a variety of extra-uterine locations. Abdominal wall scar endometriosis usually presents as a cutaneous or subcutaneous mass which can be investigated easily by the noninvasive method of fine needle aspiration cytology (FNAC).

Methods

FNA was performed by a cytopathologist on three patients presenting with varying sized swellings near the cesarean section scar.

Results

The cytologic smears revealed a combination of epithelial cells, stromal cells, and variable number of hemosiderin-laden macrophages. A diagnosis of endometriosis was provided on FNAC and later confirmed on histopathology.

Conclusions

FNAC is a valuable, cost-effective. and safe tool for diagnosing scar endometriosis and thus permits correct management of the patient.
Left-sided Canal of Nuck Endometriosis: A Case Report
Authors: Bendon Charlotte L. , Goodacre Tim EE. , Kennedy Stephen H.
Published: July 2019

Objective

To report a case of left-sided canal of Nuck endometriosis arising in the absence of a history, or magnetic resonance imaging (MRI) evidence of pelvic endometriosis

Design

Case report

Setting

UK Teaching Hospital

Patient(s)

26 year old nulliparous female without a history of endometriosis presenting with a painful, left-sided groin lump and cyclical fluctuation of symptoms. MRI confirmed features in keeping with endometriosis of the canal of Nuck.

Intervention(s)

Open excision of the lesion.

Main outcome measure(s)

Symptom free at two months.

Results

Histological analysis confirmed the left-sided lesion to be endometriosis. This is an unusual presentation of canal of Nuck endometriosis being left-sided and arising in the absence of evidence of pre-existing pelvic endometriosis, which was successfully managed by surgical excision.

Conclusions

Canal of Nuck endometriosis is a rare but important differential diagnosis of a groin lump in females, which may arise in the absence of pelvic disease, and may be managed successfully by surgical excision.
The Philosophical Case for Robot Friendship
Authors: Danaher John
Published: July 2019

Friendship is an important part of the good life. While many roboticists are eager to create friendlike robots, many philosophers and ethicists are concerned. They argue that robots cannot really be our friends, but can only fake the emotional and behavioral cues we associate with friendship. Consequently, we should resist the drive to create robot friends. In this article, I argue that the philosophical critics are wrong. Using the classic virtue-ideal of friendship, I argue that robots can plausibly be considered our virtue friends—that to do so is philosophically reasonable. Furthermore, I argue that even if robots cannot be our virtue friends, they can fulfil other important friendship roles, and can complement and enhance the virtue friendships between human beings.