bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Demonstration of a Multichannel Elastic Wave Filter in a Phononic Crystal Slab
Authors: Faiz Mohd Syafiq , Addouche Mahmoud , Zain Ahmad Rifqi Md. , Siow Kim S. , Chaalane Amar , Khelif Abdelkrim
Published: July 2020

With the aim of selecting particular frequencies of interest and rejecting others, the waveguiding and filtering properties of a two-dimensional phononic crystal slab are investigated in the context of a filtering application. To this end, we designed and manufactured a metallic device that consists of a square lattice of cylindrical pillars mounted on the top of a plate by using 3D printing technology. We respectively explored the theoretical and experimental characteristics of the device by using finite element method, a Micro System Analyzer (MSA) and a scanning laser Doppler vibrometer. The proposed device shows a complete band gap for Lamb wave around 0.3 MHz with a relative band-width of 30 % . Tailorable waveguides are realized inside this phononic crystal by inserting several space gaps to achieve a demultiplexing effect through the splitting of an acoustic signal towards three different bandpass frequency channels. The demultiplexing performance has been experimentally demonstrated by achieving rejection levels up to 60 dB. The proposed phononic platform can have a significant impact in signal processing as well as droplet manipulation for biological applications.
Optimization Design of the Mix Ratio of a Nano-TiO2/CaCO3-Basalt Fiber Composite Modified Asphalt Mixture Based on Response Surface Methodology
Authors: Gong Yafeng , Song Jiaxiang , Bi Haipeng , Tian Zhenhong
Published: July 2020

This research optimizes the mix ratio of nano-TiO2/CaCO3 (NTC)-basalt fiber (BF) composite modified asphalt mixture. Based on the Box–Behnken method and the response surface method, a three-factor and three-level test was designed. The input indicators were the asphalt–aggregate ratio, NTC content, and BF content. The output indicators were the density, air voids, Marshall stability, flow value, voids in mineral aggregate (VMA), and voids filled with asphalt (VFA) values of the asphalt mixture. The response surface model was established according to the test response index value. Then, the function was fitted through multiple regression equations and multivariate analysis of variance was performed. Finally, according to the specification requirements and engineering needs, the selected conditions of each response value were determined to optimize the asphalt–aggregate ratio and the contents of NTC and BF, and the predicted values were verified through the measured data. The test results show that the optimal contents of NTC and BF and the optimal asphalt–aggregate ratio were 5.1%, 3.9%, and 5.67%, respectively. By comparing the measured Marshall test index value with the predicted value, the minimum relative error was 0.096% and the maximum error was 6.960%. The results show that response surface methodology can be used to optimize the mix ratio of composite modified asphalt mixtures.
Investigation on Key Parameters in the Fabrication of Stamps for Transfer Printing of Micro Devices
Authors: Su Changwen , Lin Yue , Shih Tien-Mo , Lu Hao , Gao Yang , Huang Jia-En , Lu Yi-Jun , Wu Tingzhu , Chen Zhong , Guo Weijie
Published: July 2020

For the past few years, the transfer printing method has been developed and has secured numerous advantages. Here, via both experiments and analyses, we have focused on identifying key parameters and optimizing their values in the fabrication process of stamps for transfer-printing micro-devices. Specifically, the elastic modulus of posts is measured using the atomic force microscope and the Derjaguin, Muller, and Toporov model. Based on mold morphologies data, we subsequently explore the law of photoresist development under different design widths as well as development time, establish mathematical models, and offer relevant explanations for the formation of various developmental topographies. Furthermore, the relationship between the elastic modulus and these stamp-fabrication parameters has also been analyzed and confirmed. Hopefully, the proposed work can provide the guidance for fabricating reliable stamps in the future.
Strength Characteristics and Slope Stability Analysis of Expansive Soil with Filled Fissures
Authors: Dai Zhangjun , Guo Jianhua , Luo Hongming , Li Jian , Chen Shanxiong
Published: July 2020

Fissured expansive soils were widely distributed in the South-to-North Water Transfer Project. Most of the fissures were filled with clay, which controlled the stability of the slope. With the method of layered filling—bevel cutting—refilling and a modular design idea, the sample with a filled fissure preparation device for triaxial test was designed. After setting the filled fissures of gray-green clay in the expansive soil, triaxial tests were carried out for the samples with no filled fissures and with filled fissures with inclination angles of 15°, 30°, and 45°. Then, considering the spatial distribution and the strength of the filled fissures in the slope, the stability analysis method for the expansive soil slope with filled fissures was proposed. The stability of a typical slope in Nanyang was analyzed. The results show that the c of expansive soil with filled fissures was about 12 to 15 kPa and the φ was 3° to 6°. Filled fissures had an attenuation effect on the strength of the expansive soil. The larger the inclination of filled fissures, the more significant the effect of soil strength attenuation. The fissured slope stability was controlled by the filled fissures. The sliding surface was affected by the vertical fissures on the top of the slope and the slow-inclined long-large fissures in the slope, and the shape of the sliding surface was a broken line, which was basically consistent with the actual landslide.
Evaluation of Rainfall Forecasts by Three Mesoscale Models during the Mei-Yu Season of 2008 in Taiwan. Part III: Application of an Object-Oriented Verification Method
Authors: Wang Chung-Chieh , Paul Sahana , Lee Dong-In
Published: July 2020

In this study, the performances of Mei-yu (May–June) quantitative precipitation forecasts (QPFs) in Taiwan by three mesoscale models: the Cloud-Resolving Storm Simulator (CReSS), the Central Weather Bureau (CWB) Weather Research and Forecasting (WRF), and the CWB Non-hydrostatic Forecast System (NFS) are explored and compared using an newly-developed object-oriented verification method, with particular focus on the various properties or attributes of rainfall objects identified. Against a merged dataset from ~400 rain gauges in Taiwan and the Tropical Rainfall Measuring Mission (TRMM) data in the 2008 season, the object-based analysis is carried out to complement the subjective analysis in a parallel study. The Mei-yu QPF skill is seen to vary with different aspects of rainfall objects among the three models. The CReSS model has a total rainfall production closest to the observation but a large number of smaller objects, resulting in more frequent and concentrated rainfall. In contrast, both WRF and NFS tend to under-forecast the number of objects and total rainfall, but with a higher proportion of bigger objects. Location errors inferred from object centroid locations appear in all three models, as CReSS, NFS, and WRF exhibit a tendency to simulate objects slightly south, east, and northwest with respect to the observation. Most rainfall objects are aligned close to an E–W direction in CReSS, in best agreement with the observation, but many towards the NE–SW direction in both WRF and NFS. For each model, the objects are matched with the observed ones, and the results of the matched pairs are also discussed. Overall, though preliminarily, the CReSS model, with a finer grid size, emerges as best performing model for Mei-yu QPFs.
Idealized Simulations of City-Storm Interactions in a Two-Dimensional Framework
Authors: Naylor Jason
Published: July 2020

Numerous studies have identified spatial variability in convective parameters such as rainfall totals and lightning flashes in the vicinity of large urban areas, yet many questions remain regarding the storm-scale processes that are altered during interaction with a city as well as which urban features are most responsible for storm modification. This study uses an idealized, two-dimensional cloud model to investigate structural and evolutionary changes in a squall line as it passes over a simplified representation of a large city. A parameter space exploration is done in which the parameters of the city—surface temperature and surface roughness length—are systemically increased relative to the region surrounding the idealized city. The resultant suite of simulations demonstrates that storm parameters such as vertical velocity, hydrometeor mass, upward mass flux, and buoyant accelerations are enhanced when the storm passes over the idealized city. No such enhancement occurs in the control simulation without an idealized city.
Preface: Ozone Evolution in the Past and Future
Authors: Rozanov Eugene
Published: July 2020

The stratospheric ozone plays an important role in the protection of the biosphere from the dangerous ultraviolet radiation of the sun [...]
The Impact of MJO, Kelvin, and Equatorial Rossby Waves on the Diurnal Cycle over the Maritime Continent
Authors: Worku Lakemariam , Mekonnen Ademe , Schreck Carl
Published: July 2020

The impacts of the Madden–Julian Oscillation (MJO), Kelvin waves, and Equatorial Rossby (ER) waves on the diurnal cycle of rainfall and types of deep convection over the Maritime Continent are investigated using rainfall from the Tropical Rainfall Measurement Mission Multisatellite Precipitation Analysis and Infrared Weather States (IR–WS) data from the International Satellite Cloud Climatology Project. In an absolute sense, the MJO produced its strongest modulations of rainfall and organized deep convection over the islands, when and where convection is already strongest. The MJO actually has a greater percentage modulation over the coasts and seas, but it does not affect weaker diurnal cycle there. Isolated deep convection was also more prevalent over land during the suppressed phase, while organized deep convection dominated the enhanced phase, consistent with past work. This study uniquely examined the effects of Kelvin and ER waves on rainfall, convection, and their diurnal cycles over the Maritime Continent. The modulation of convection by Kelvin waves closely mirrored that by the MJO, although the Kelvin wave convection continued farther into the decreasing phase. The signals for ER waves were also similar but less distinct. An improved understanding of how these waves interact with convection could lead to improved subseasonal forecast skill.
Prospective Memory, Sleep, and Age
Authors: Occhionero Miranda , Tonetti Lorenzo , Fabbri Marco , Boreggiani Michele , Martoni Monica , Giovagnoli Sara , Natale Vincenzo
Published: July 2020

It is reported that sleep enhances prospective memory (PM), but it remains to be understood whether this influence is moderated by age, since sleep changes across the lifespan. To this end, we performed a retrospective study in a naturalistic setting in a large life span sample: 397 healthy participants (227 females) from middle childhood (nine years old) to late adulthood (70 years old). Participants were requested to perform a naturalistic activity-based PM task, namely, to remember to press the event-marker button of an actigraph when they went to bed (activity 1) and when they got out of bed (activity 2) after nocturnal sleep. The percentages of button presses were the measure of our activity-based PM task. For activities 1 and 2, we separately performed a moderation model with actigraphic sleep parameters (sleep efficiency, midpoint of sleep, and total sleep time) as predictors of PM performance with age as a moderator factor. With reference to activity 1, we observed a significant interaction between sleep efficiency and age, showing a decrease in PM performance with the increase in sleep efficiency in the low age group. Only age was a significant (negative) predictor of PM in activity 2, i.e., with increasing age, PM performance significantly decreased. The present study shows, in a large life span sample, that sleep does not seem to play a relevant predictive role of activity-based PM performance.
Determination of Extinction Coefficients for Describing Gas Adsorption on Heterogeneous Catalysts Using In-Situ DRIFT Spectroscopy
Authors: Glorius Maja , Reich Tobias , Breitkopf Cornelia
Published: July 2020

Diffuse reflection infrared Fourier transform (DRIFT) spectra have been quantitatively evaluated to determine unknown extinction coefficients as well as the number of active surface centers and the amount of adsorbed species. Sulfated zirconia with n-butane as probe gas was used as model system. For quantitative evaluation of n-butane adsorption at 323 K, the sulfate band S=O at 1400 cm−1 was chosen. During adsorption, this band is red-shifted to lower wavenumbers accompanied by a structural change of the band indicating isomerization reaction. By analyzing difference spectra and determining the areas of the selected band, the extinction coefficients as well as the number of active centers and the amount of chemisorbed n-butane were calculated. The quantitative evaluation results in a mean internal decadic extinction coefficient of 60 cm−1 µmol−1, an average amount of n-butane adsorbed to the sulfated zirconia of about 4 μmol, and a number of active centers of around 21 μmol/g. These results correspond very well with values from the literature obtained by microcalorimetry. Thus, this method is suggested to be transferred also to unknown systems of interest.
Immobilized Biocatalysts of Eversa® Transform 2.0 and Lipase from Thermomyces Lanuginosus: Comparison of Some Properties and Performance in Biodiesel Production
Authors: Martínez-Sanchez Javier A. , Arana-Peña Sara , Carballares Diego , Yates Malcom , Otero Cristina , Fernandez-Lafuente Roberto
Published: July 2020

Eversa® Transform (ET), and the lipase from Thermomyces lanuginosus (TLL), liquid commercial lipases formulations, have been immobilized on octyl agarose beads and their stabilities were compared. Immobilized and free ET forms were more thermostable than TLL formulations at pH 5.0, 7.0, and 9.0, and the ET immobilized form was more stable in the presence of 90% methanol or dioxane at 25 °C and pH 7. Specific activity versus p-nitrophenyl butyrate was higher for ET than for TLL. However, after immobilization the differences almost disappeared because TLL was very hyperactivated (2.5-fold) and ET increased the activity only by 1.6 times. The enzymes were also immobilized in octadecyl methacrylate beads. In both cases, the loading was around 20 mg/g. In this instance, activity was similar for immobilized TLL and ET using triacetin, while the activity of immobilized ET was lower using (S)-methyl mandelate. When the immobilized enzymes were used to produce biodiesel from sunflower oil and methanol in tert-butanol medium, their performance was fairly similar.
Some Energy Issues for a Nanoscale Electrostatic Potential Well in Saline Solutions
Authors: Guo Jingkun , Lei Zijin , Wang Fan , Xu Jingjing , Xu Shengyong
Published: July 2020

An electrostatic potential well may be applied to trap and manipulate charged micro- and nanoparticles. An electrostatic potential well obtained from a certain charge distribution may be used to mimic the electrostatic interactions among biomolecules in live biosystems. In this study, we present a simulation study on the trapping performance of dipole clusters, which are arranged in 10 nm-sized, pentagon-shaped structures in a saline solution. The influence of electrostatic energy, entropy, and van der Waals interaction on the trapping performance of these nanostructures is then systematically calculated. The results show that the electrostatic potential well system demonstrated a moderate trapping capability, which could be enhanced using van der Waals interactions. The entropy significantly contributes to the trapping capability. This study offers some ideas for developing practical biomimetic electrostatic tweezers and nanorobots working in an ionic solution.
A BEM for the Hydrodynamic Analysis of Oscillating Water Column Systems in Variable Bathymetry
Authors: Belibassakis Kostas , Magkouris Alexandros , Rusu Eugen
Published: July 2020

In this work, a novel Boundary Element Method (BEM) is developed and applied to the investigation of the performance of Oscillating Water Column (OWC) systems, taking into account the interaction of the incident wave field with the bottom topography. The modelling includes the effect of additional upwave walls and barriers used to modify the resonance characteristics of the device and improve its performance as the U-OWC configuration. Numerical results illustrating the effects of depth variation in conjunction with other parameters—such as chamber dimensions as well as the parameters associated with the turbine and power take-off system—on the device performance are presented and discussed. Finally, a case study is presented regarding the potential installation of an OWC in a selected port site in the Black Sea, characterized by a good wave energy potential, on the coast of Romania.
Maximum Utilization of Dynamic Rating Operated Distribution Transformer (DRoDT) with Battery Energy Storage System: Analysis on Impact from Battery Electric Vehicles Charging
Authors: Talpur Saifal , Tjing Lie Tek , Zamora Ramon , Priyo Das Bhaba
Published: July 2020

This paper investigates thermal overloading, voltage dips and insulation failure across a distribution transformer (DT), under residential and battery electric vehicle (BEV) loadings. The objective of this paper is to discuss the charging impact of BEVs on voltage across consumer-service points, as well as across the life of paper insulation under varying ambient temperatures (during winter and summer), with and without a centralized battery energy storage system (BESS). This study contributes in two ways. The first part of this study deals with coordinated and uncoordinated BEV charging scenarios. The second part of this study deals with maximum utilization of a test DT rated under dynamic thermal rating (DRoDT). The DRoDT integration with BESS is carried out to flatten the load spikes, to obtain maximum DT utilization, to achieve active power and voltage supports in addition to an enhanced DT lifespan. The obtained results indicate that, when test DT operates under the proposed hybrid technique (combining both dynamic transformer ratings and a centralized BESS), it attains maximum utilization, lower hot-spot temperature, enhanced lifespan, less degraded paper insulation and an improved voltage across each consumer service point. The proposed technique is furthermore found effective in maintaining the loading across the distribution transformer within the nominal limits. However, under excess loading during peak hours, the proposed technique provides relief to the DT to a certain extent. To achieve an optimal DT operation and an enhanced BESS lifespan, the BESS is operated under nominal charging and discharging cyclic limits. Under the proposed DRoDT integration with BESS, DT attains 25.9% more life when loaded with coordinated BEV charging, in comparison to no BESS integration under the same loading scenario. The worst loading due to uncoordinated BEV charging also brings 51% increase in DT life when loaded under the proposed technique.
Nanomaterial-Based Drilling Fluids for Exploitation of Unconventional Reservoirs: A Review
Authors: Ali Muhammad , Jarni Husna Hayati , Aftab Adnan , Ismail Abdul Razak , Saady Noori M. Cata , Sahito Muhammad Faraz , Keshavarz Alireza , Iglauer Stefan , Sarmadivaleh Mohammad
Published: July 2020

The world’s energy demand is steadily increasing where it has now become difficult for conventional hydrocarbon reservoir to meet levels of demand. Therefore, oil and gas companies are seeking novel ways to exploit and unlock the potential of unconventional resources. These resources include tight gas reservoirs, tight sandstone oil, oil and gas shales reservoirs, and high pressure high temperature (HPHT) wells. Drilling of HPHT wells and shale reservoirs has become more widespread in the global petroleum and natural gas industry. There is a current need to extend robust techniques beyond costly drilling and completion jobs, with the potential for exponential expansion. Drilling fluids and their additives are being customized in order to cater for HPHT well drilling issues. Certain conventional additives, e.g., filtrate loss additives, viscosifier additives, shale inhibitor, and shale stabilizer additives are not suitable in the HPHT environment, where they are consequently inappropriate for shale drilling. A better understanding of the selection of drilling fluids and additives for hydrocarbon water-sensitive reservoirs within HPHT environments can be achieved by identifying the challenges in conventional drilling fluids technology and their replacement with eco-friendly, cheaper, and multi-functional valuable products. In this regard, several laboratory-scale literatures have reported that nanomaterial has improved the properties of drilling fluids in the HPHT environment. This review critically evaluates nanomaterial utilization for improvement of rheological properties, filtrate loss, viscosity, and clay- and shale-inhibition at increasing temperature and pressures during the exploitation of hydrocarbons. The performance and potential of nanomaterials, which influence the nature of drilling fluid and its multi-benefits, is rarely reviewed in technical literature of water-based drilling fluid systems. Moreover, this review presented case studies of two HPHT fields and one HPHT basin, and compared their drilling fluid program for optimum selection of drilling fluid in HPHT environment.
A Simple Analytical Model of Static Eccentricity for PM Brushless Motors and Validation through FEM Analysis
Authors: Del Pizzo Andrea , Di Noia Luigi Pio , Fedele Emanuele
Published: July 2020

The paper firstly summarizes a simple analytical model of the air gap flux-density distribution for isotropic permanent magnet (PM) synchronous machines, in the presence of static eccentricity. The model was proposed by the authors in a previous paper and is based on an efficacious analytical expression of the variable length of air gap magnetic field lines which occur in eccentric brushless machines with surface-mounted permanent magnets. The approximate expression of the air gap field makes it possible to achieve a mathematical model with concentrated parameters close to that of a PM machine without eccentricity. The expression of the armature voltages and electromagnetic torque are found, also with reference to steady-state operating conditions at fixed rotor speed and impressed currents. The differences introduced by the considered type of eccentricity are evaluated and highlighted especially with reference to the air gap inductance and to waveforms and frequency spectra of voltages and shaft torque. Numerical results in a case-study of an 8-pole, 110 kW PM motor are compared to those obtained by using finite element analysis.
Experimental Study of Premixed Gasoline Surrogates Burning Velocities in a Spherical Combustion Bomb at Engine Like Conditions
Authors: Reyes Miriam , Tinaut Francisco V. , Camaño Alexandra
Published: July 2020

In this work are presented experimental values of the burning velocity of iso-octane/air, n-heptane/air and n-heptane/toluene/air mixtures, gasoline surrogates valid over a range of pressures and temperatures similar to those obtained in internal combustion engines. The present work is based on a method to determine the burning velocities of liquid fuels in a spherical constant volume combustion bomb, in which the initial conditions of pressure, temperature and fuel/air equivalence ratios can be accurately established. A two-zone thermodynamic diagnostic model was used to analyze the combustion pressure trace and calculate thermodynamic variables that cannot be directly measured: the burning velocity and mass burning rate. This experimental facility has been used and validated before for the determination of the burning velocity of gaseous fuels and it is validated in this work for liquid fuels. The values obtained for the burning velocity are expressed as power laws of the pressure, temperature and equivalence ratio. Iso-octane, n-heptane and mixtures of n-heptane/toluene have been used as surrogates, with toluene accounting for the aromatic part of the fuel. Initially, the method is validated for liquid fuels by determining the burning velocity of iso-octane and then comparing the results with those corresponding in the literature. Following, the burning velocity of n-heptane and a blend of 50% n-heptane and 50% toluene are determined. Results of the burning velocities of iso-octane have been obtained for pressures between 0.1 and 0.5 MPa and temperatures between 360 and 450 K, for n-heptane 0.1–1.2 MPa and 370–650 K, and for the mixture of 50% n-heptane/50% toluene 0.2–1.0 MPa and 360–700 K. The power law correlations obtained with the results for the three different fuels show a positive dependence with the initial temperature and the equivalence ratio, and an inverse dependence with the initial pressure. Finally, the comparison of the burning velocity results of iso-octane and n-heptane with those obtained in the literature show a good agreement, validating the method used. Analytical expressions of burning velocity as power laws of pressure and unburned temperature are presented for each fuel and equivalence ratio.
Active Charge Balancing Strategy Using the State of Charge Estimation Technique for a PV-Battery Hybrid System
Authors: Ohirul Qays Md , Buswig Yonis , Hossain Md Liton , Abu-Siada Ahmed
Published: July 2020

Charging a group of series-connected batteries of a PV-battery hybrid system exhibits an imbalance issue. Such imbalance has severe consequences on the battery activation function and the maintenance cost of the entire system. Therefore, this paper proposes an active battery balancing technique for a PV-battery integrated system to improve its performance and lifespan. Battery state of charge (SOC) estimation based on the backpropagation neural network (BPNN) technique is utilized to check the charge condition of the storage system. The developed battery management system (BMS) receives the SOC estimation of the individual batteries and issues control signal to the DC/DC Buck-boost converter to balance the charge status of the connected group of batteries. Simulation and experimental results using MATLAB-ATMega2560 interfacing system reveal the effectiveness of the proposed approach.
New Insights for Understanding the Structural Deformation Style of the Strike-Slip Regime along the Wadi Shueib and Amman-Hallabat Structures in Jordan Based on Remote Sensing Data Analysis
Authors: Al Hseinat Mu’ayyad , Al-Rawabdeh Abdulla , Al-Zidaneen Malek , Ghanem Hind , Al-Taj Masdouq , Diabat Abdullah , Jarrar Ghaleb , Atallah Mohammad
Published: July 2020

This paper presents new findings that contribute to the understanding of the deformational style of the Wadi Shueib Structure (WSS) and the Amman-Halabat Structure (AHS) and their relationship with the regional tectonic regime of the Dead Sea Transform Fault (DSTF). Our research utilized Landsat-8 OLI imagery for the automatic extraction of lineaments, and our lineament mapping was facilitated by processing and digital image enhancement using principal component analysis (PCA). Our data revealed a relatively higher density of lineaments along the extension of the major faults of the WSS and AHS. However, a relatively lower density of lineaments was shown in areas covered by recent deposits. Two major lineament trends were observed (NNE-SSW and NW-SE) in addition to a minor one (NE-SW), and most of these lineaments are parallel to the orientation of the WSS and AHS. We offer the supposition that the DSTF has merged into the major faults of the WSS and AHS. We further suppose that these faults were reactivated as a restraining bend composed of active strike-slip fault branches that developed due to the NNW-SSE-trending Dead Sea transpressional stress field. Depending on the relationship between the direction of the WSF and AHF strands and the regional tectonic displacement along the DSTF, thrust components are present on faults with horsetail geometry, and these movements are accompanied by folding and uplifting. Thus, the major faults of the WSS and AHS represent a contractional horsetail geometry with associated folding and thrusting deformation.
Senegal, the African Slave Trade, and the Door of No Return: Giving Witness to Gorée Island
Authors: Fofana Dalla Malé
Published: July 2020

Recently, the Senegalese people have learned to speak more openly of their history. But, as late as the 1980s—the years of my youth and early schooling—the wounds of colonialism were still fresh. I contend that slavery had been so powerful a blow to the Senegalese ethos that we—my family, friends, and schoolmates—did not speak about it. The collective trauma and shame of slavery was apparently so powerful that we sought to repress it, keeping it hidden from ourselves. We were surrounded by its evidence, but chose not to see it. Such was my childhood experience. As an adult, I understand that repression never heals wounds. The trauma remains as a haunting presence. But one can discover its “living presence,” should one choose to look. Just 5.2 km off the west African coast of Senegal lies Gorée Island, where millions of Africans were held captive while awaiting transport into slavery. Much of the four-century history of the African slave trade passed through Senegal, where I grew up. In this essay, I explore the history of the island and its role in the slave trade. I describe my own coming to terms with this history—how it has haunted me since my youth. And I argue for the role of visual rhetorics in the formation (and affirmation) of Senegalese ethos. As Baumlin and Meyer (2018) remind us, we need to speak, in order to be heard, in order to be seen: Such is an assumption of rhetorical ethos. And the reverse, as I shall argue, may be true, too: Sometimes we need to see (or be seen), in order to know what to speak and how to be heard. It is for this reason that we need more films written, directed, produced, and performed by Africans (Senegalese especially).
Collaborative Archaeology, Relational Memory, and Stakeholder Action at Three Henequen Haciendas in Yucatan, Mexico
Authors: Zimmermann Mario , Hernández Álvarez Héctor , Fernández Souza Lilia , Venegas de la Torre Joaquín , Pantoja Díaz Luis
Published: July 2020

In the Mexican state of Yucatán, the Industrial Revolution is intimately linked to the cultivation and commercialization of henequen (Agave fourcroydes). The second half of the nineteenth and the first decade of the twentieth century are most often referred to as the region’s Gilded Age. Some local families accrued immense wealth, while many peasants were essentially enslaved. The city of Mérida saw the construction of magnificent mansions, and the new port of Progreso was connected through thousands of kilometers of railroads. At the same time, the rural landscape experienced the foundation of countless new and the expansion of existing haciendas. In this article, we provide a comparison of the relational memory of local communities regarding three of these historical settlements: San Pedro Cholul, San Antonio Nohuayún, and San Antonio Sihó. We present the circumstances leading to the historical archaeology project at San Pedro and recount our efforts at involving its descendant community. In the face of the recent destruction of San Pedro’s core buildings, we end with a discussion about the potential fates of Yucatan’s henequen haciendas and a series of suggestions on how to safeguard related material remains, while allowing stakeholders to benefit from historic preservation.
Biochar—A Panacea for Agriculture or Just Carbon?
Authors: Tenic Elvir , Ghogare Rishikesh , Dhingra Amit
Published: July 2020

The sustainable production of food faces formidable challenges. Foremost is the availability of arable soils, which have been ravaged by the overuse of fertilizers and detrimental soil management techniques. The maintenance of soil quality and reclamation of marginal soils are urgent priorities. The use of biochar, a carbon-rich, porous material thought to improve various soil properties, is gaining interest. Biochar (BC) is produced through the thermochemical decomposition of organic matter in a process known as pyrolysis. Importantly, the source of organic material, or ‘feedstock’, used in this process and different parameters of pyrolysis determine the chemical and physical properties of biochar. The incorporation of BC impacts soil–water relations and soil health, and it has been shown to have an overall positive impact on crop yield; however, pre-existing physical, chemical, and biological soil properties influence the outcome. The effects of long-term field application of BC and how it influences the soil microcosm also need to be understood. This literature review, including a focused meta-analysis, summarizes the key outcomes of BC studies and identifies critical research areas for future investigations. This knowledge will facilitate the predictable enhancement of crop productivity and meaningful carbon sequestration.
Audit of Museum Marketing Communication in the Modern Management Context
Authors: Kupec Václav , Lukáč Michal , Štarchoň Peter , Pajtinková Bartáková Gabriela
Published: July 2020

Marketing communication is a concise part of modern museum management. Museums operate in a competitive environment; therefore, it is important to pay sustained attention to every component of a given museum’s marketing communication. Changes, international trends, and visitor preferences have an influence on marketing communication. Museum management must devote expert deliberation towards determining which components of their marketing communication are significant for museum visitors. Moreover, the effectiveness of the use of expenses plays an important role in museum management; it is also essential to combine effectively the individual components of marketing communication. The present research aims to find a correlation between the components of museum marketing communication, which is not being addressed in detail in the contemporary research. The aim of the research is therefore to determine the dependence amongst elements of the marketing communication of museums on questioning the visitors. The aim was achieved by implementing the modern audit approach and empirical research into marketing communication: the Paper Aided Personal Interview (PAPI) method with a Likert scale, a reliability check with Cronbach’s alpha, and dependency determination with Pearson’s correlation. All results were investigated through the use of a questionnaire on the international EU 27 sample of museum visitors. These conclusions allow museum management to build their marketing communication on the principles of Economy, Efficiency, and Effectiveness (the 3E principles).
Improved Monitoring of Grapholita molesta (Lepidoptera: Tortricidae) in Stone Fruit Orchards with a Pheromone-Kairomone Combination Lure
Authors: Preti Michele , Knight Alan L. , Angeli Sergio
Published: July 2020

Monitoring oriental fruit moth Grapholita molesta Busck (Lepidoptera: Tortricidae), populations based on counts in sex pheromone-baited traps within sex pheromone-treated orchards for mating disruption (MD) is challenging since male orientation to traps is disrupted. In this study, we evaluated a new commercial pheromone–kairomone combination lure for G. molesta (Pherocon® OFM Combo™ Dual™), which combines the G. molesta and Cydia pomonella L. sex pheromones with a blend of acetic acid and terpinyl acetate. Trap comparisons were performed in 33 trials in peach and nectarine orchards under MD (24) or non-MD (9) during the 2018–2019 period in Italy. Male and total moth captures in traps baited with the combination lure were significantly greater than in traps with G. molesta pheromone in both years and across both pheromone treatments. The proportion of females in the total moth captures using the combination lure averaged ca. 7% across all trials. The by-catch of non-targets, i.e., Apis mellifera L., was low in traps baited either with the combination and the sex pheromone lure, while trap color (white) affected the capture of beneficials but not of the target pest. Our study proves that this combination lure can improve the monitoring and management for G. molesta in stone fruits. New studies are needed to define action thresholds to trigger supplemental control methods to MD. Secondly, female-based monitoring lures should be further developed to improve management strategies.
Effect of MoSi2-Si3N4/SiC Multi-Layer Coating on the Oxidation Resistance of Carbon/Carbon Composites above 1770 K
Authors: Abbas Imran , Wang Yanxiang , Elahi Hassan , Siddiqui Muhammad Ali , Ullah Mudaser , Qayyum Faisal
Published: July 2020

To improve the oxidation resistance of carbon/carbon composites at high temperatures (>1770 K), they were coated with MoSi2-Si3N4/SiC. The slurry and pack cementation methods were adopted to deposit the inner SiC layer and outer MoSi2-Si3N4 layer. The phase composition, microstructure, and elemental distributions in the coating were analyzed using SEM, XRD, EDS, and Raman spectroscopy. Oxidation tests show that the deposited multi-layer coating can protect the carbon/carbon matrix from oxidation at high temperatures (>1770 K) for 150h and that the coating can withstand 40 thermal cycles between 1773 and 300 K. It is observed that Si3N4 assists in the formation of a dense SiO2 layer at a high temperature, which plays a vital role in increasing the thermal cyclic and oxidation resistance of the coating itself. The weight loss of coated carbon/carbon composite is attributed to the formation of micro-cracks and diffusion of SiO2, MoO3, and N2 out of the material at high temperatures.
Evaluation of the Weighted Mean X-ray Energy for an Imaging System Via Propagation-Based Phase-Contrast Imaging
Authors: Seifert Maria , Weule Mareike , Cipiccia Silvia , Flenner Silja , Hagemann Johannes , Ludwig Veronika , Michel Thilo , Neumayer Paul , Schuster Max , Wolf Andreas , Anton Gisela , Funk Stefan , Akstaller Bernhard
Published: July 2020

For imaging events of extremely short duration, like shock waves or explosions, it is necessary to be able to image the object with a single-shot exposure. A suitable setup is given by a laser-induced X-ray source such as the one that can be found at GSI (Helmholtzzentrum für Schwerionenforschung GmbH) in Darmstadt (Society for Heavy Ion Research), Germany. There, it is possible to direct a pulse from the high-energy laser Petawatt High Energy Laser for Heavy Ion eXperiments (PHELIX) on a tungsten wire to generate a picosecond polychromatic X-ray pulse, called backlighter. For grating-based single-shot phase-contrast imaging of shock waves or exploding wires, it is important to know the weighted mean energy of the X-ray spectrum for choosing a suitable setup. In propagation-based phase-contrast imaging the knowledge of the weighted mean energy is necessary to be able to reconstruct quantitative phase images of unknown objects. Hence, we developed a method to evaluate the weighted mean energy of the X-ray backlighter spectrum using propagation-based phase-contrast images. In a first step wave-field simulations are performed to verify the results. Furthermore, our evaluation is cross-checked with monochromatic synchrotron measurements with known energy at Diamond Light Source (DLS, Didcot, UK) for proof of concepts.
An Iterative Size Effect Model of Surface Generation in Finish Machining
Authors: Brown Ian , Schoop Julius
Published: July 2020

In this work, a geometric model for surface generation of finish machining was developed in MATLAB, and subsequently verified by experimental surface roughness data gathered from turning tests in Ti-6Al4V. The present model predicts the behavior of surface roughness at multiple length scales, depending on feed, nose radius, tool edge radius, machine tool error, and material-dependent parameters—in particular, the minimum effective rake angle. Experimental tests were conducted on a commercial lathe with slightly modified conventional tooling to provide relevant results. Additionally, the model-predicted roughness was compared against pedigreed surface roughness data from previous efforts that included materials 51CrV4 and AL 1075. Previously obscure machine tool error effects have been identified and can be modeled within the proposed framework. Preliminary findings of the model’s relevance to subsurface properties have also been presented. The proposed model has been shown to accurately predict roughness values for both long and short surface roughness evaluation lengths, which implies its utility not only as a surface roughness prediction tool, but as a basis for understanding three-dimensional surface generation in ductile-machining materials, and the properties derived therefrom.
Zooplankton Distribution and Community Structure in the Pacific and Atlantic Sectors of the Southern Ocean during Austral Summer 2017–18: A Pilot Study Conducted from Ukrainian Long-Liners
Authors: Pakhomov Evgeny A. , Pshenichnov Leonid K. , Krot Anatoly , Paramonov Valery , Slypko Ilia , Zabroda Pavel
Published: July 2020

Preliminary results of the pilot study of the zooplankton in the region between the Ross and Scotia Seas from November 2017 to April 2018 are presented. In total, 53 zooplankton samples were collected in the top 100 m water layer using vertical tows of a 0.1 m2 Juday net from four Ukrainian longliners operating during the Antarctic toothfish fishery. Total zooplankton abundance ranged from 3 to 2836 ind m−3 with a global mean of 360 ± 550 (±1 SD) ind m−3. The highest abundances were recorded at the northeastern Ross Sea. At those stations, small copepods (mainly Oithona spp., Oncaea spp., Ctenocalanus spp. and copepod nauplii) numerically dominated the samples. Total biomass ranged from 0.3 to 85 mg DW m−3 with a mean of 10.9 ± 14.5 mg DW m−3. The highest biomasses were recorded at the eastern Ross Sea, where pelagic tunicates Salpa thompsoni, siphonophores and ctenophora Callianira sp. accounted for >90% of total zooplankton biomass. At other stations, zooplankton biomass generally ranged from 5 to 20 mg DW m−3 with no clear pattern in distribution. The community composition was driven by the sampling latitude and/or season rather than longitudinally. This pilot study emphasized the unique opportunity to investigate zooplankton dynamics in the regions traditionally not sampled during the oceanographic surveys. It also created unprecedented opportunities to increase the seasonal and geographical zooplankton sampling coverage using ships of opportunity at a fraction of a dedicated oceanographic survey costs. The potential of such surveys are enormous in both providing invaluable information, contributing to existing long-term databases and enhancing an international collaboration in the Southern Ocean, particularly in light of recent modeling initiatives of the whole Antarctic system undertaken by the Commission for the Conservation of Antarctic Marine Living Resources.
Numerical Approach for Solving Delay Differential Equations with Boundary Conditions
Authors: Jaaffar Nur Tasnem , Abdul Majid Zanariah , Senu Norazak
Published: July 2020

In the present paper, a fifth-order direct multistep block method is proposed for solving the second-order Delay Differential Equations (DDEs) directly with boundary conditions using constant step size. In many life sciences applications, a delay plays an essential role in modelling natural phenomena with data simulation. Thus, an efficient numerical method is needed for the numerical treatment of time delay in the applications. The proposed direct block method computes the numerical solutions at two points concurrently at each computed step along the interval. The types of delays involved in this research are constant delay, pantograph delay, and time-dependent delay. The shooting technique is utilized to deal with the boundary conditions by applying a Newton-like method to guess the next initial values. The analysis of the proposed method based on the order, consistency, convergence, and stability of the method are discussed in detail. Four tested problems are presented to measure the efficiency of the developed direct multistep block method. The numerical simulation indicates that the proposed direct multistep block method performs better than existing methods in terms of accuracy, total function calls, and execution times.
Dynamics of Periodic Waves in a Neural Field Model
Authors: Bessonov Nikolai , Beuter Anne , Trofimchuk Sergei , Volpert Vitaly
Published: July 2020

Periodic traveling waves are observed in various brain activities, including visual, motor, language, sleep, and so on. There are several neural field models describing periodic waves assuming nonlocal interaction, and possibly, inhibition, time delay or some other properties. In this work we study the influences of asymmetric connectivity functions and of time delay for symmetric connectivity functions on the emergence of periodic waves and their properties. Nonlinear wave dynamics are studied, including modulated and aperiodic waves. Multiplicity of waves for the same values of parameters is observed. External stimulation in order to restore wave propagation in a damaged tissue is discussed.
Parameter Identification in Nonlinear Mechanical Systems with Noisy Partial State Measurement Using PID-Controller Penalty Functions
Authors: Manikantan R. , Chakraborty Sayan , Uchida Thomas K. , Vyasarayani C. P.
Published: July 2020

Dynamic models of physical systems often contain parameters that must be estimated from experimental data. In this work, we consider the identification of parameters in nonlinear mechanical systems given noisy measurements of only some states. The resulting nonlinear optimization problem can be solved efficiently with a gradient-based optimizer, but convergence to a local optimum rather than the global optimum is common. We augment the dynamic equations with a morphing parameter and a proportional–integral–derivative (PID) controller to transform the objective function into a convex function; the global optimum can then be found using a gradient-based optimizer. The morphing parameter is used to gradually remove the PID controller in a sequence of steps, ultimately returning the model to its original form. An optimization problem is solved at each step, using the solution from the previous step as the initial guess. This strategy enables use of a gradient-based optimizer while avoiding convergence to a local optimum. The efficacy of the proposed approach is demonstrated by identifying parameters in the van der Pol–Duffing oscillator, a hydraulic engine mount system, and a magnetorheological damper system. Our method outperforms genetic algorithm and particle swarm optimization strategies, and demonstrates robustness to measurement noise.