bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymorphism and Supramolecular Isomerism: The Impasse of Coordination Polymers
Authors: Sánchez-Férez Francisco , Pons Josefina
Published: April 2021

The chapter presented hereafter, outlines the narrow link between chemistry and crystallography that impelled the identification of polymorphism and provided a priceless grounding to understand structure-properties relationship. It was initially conceived for organic substances but actually embraced by metal–organic products, especially in the study of coordination polymers. All of the technologic advances have provided profound insights on the control of crystal structures formation revealing that any applied stimulus over a substance can undergo a structural transformation. This has led to the implementation of several methodologies in the industrial and academic segment shedding light on the source of hitherto, not well understood results.
Recent Advances in Applications of Ceramic Nanofibers
Authors: Kizildag Nuray
Published: April 2021

Ceramic materials are well known for their hardness, inertness, superior mechanical and thermal properties, resistance against chemical erosion and corrosion. Ceramic nanofibers were first manufactured through a combination of electrospinning with sol–gel method in 2002. The electrospun ceramic nanofibers display unprecedented properties such as high surface area, length, thermo-mechanical properties, and hierarchically porous structure which make them candidates for a wide range of applications such as tissue engineering, sensors, water remediation, energy storage, electromagnetic shielding, thermal insulation materials, etc. This chapter focuses on the most recent advances in the applications of ceramic nanofibers.
Wiskott-Aldrich Syndrome
Authors: Sepehrnia Saeed
Published: April 2021

The Wiskott-Aldrich syndrome (WAS) could be a rare X-linked primary immunodeficiency disorder characterized by recurrent infections, eczema, and bleeding following thrombocytopenia. Despite the rarity of this syndrome, today our understanding of the cellular and molecular basis of the pathogenesis of this disease has increased and it’s well established that this disorder encompasses a wide range of clinical disorders including immunodeficiency, atopy, autoimmunity, and cancer. Wiskott–Aldrich Syndrome protein (WASP) mutations are located throughout the gene and inhibit or regulate the conventional function of WASP. Thus classic WAS occurs when WASP is absent, X-linked thrombocytopenia when mutated WASP is expressed, and X-linked neutropenia when missense mutations occur within the Cdc42-binding site. Developments within the use of diagnostic tools, supportive care, and advances in allogeneic hematopoietic cell transplantation have remarkably reduced the mortality related to this disorder. Besides, gene therapy has provided optimistic perspectives on the treatment approaches of those patients.
Glycan and Its Role in Combating COVID-19
Authors: Kumar Chatterjee Swapan , Saha Snigdha
Published: April 2021

Newly identified beta-coronavirus i.e. the 2019 novel coronavirus is associated with a contagious transmittable respiratory disease called COVID-19. This disease has been declared as a “pandemic” by the World Health Organization (WHO). The entry of coronavirus in the human respiratory epithelial cells depends upon the interaction between host cell receptor ACE2 and viral S-glycoprotein. However, this type of molecular recognition in between cell surface receptors and envelope glycoproteins are mediated by specific glycan epitopes and attribute to viral entry through membrane fusion. Glycans are essential biomolecules made by all living organisms, have roles in serving structure, energy storage, and system regulatory purposes. The glycan shield plays a crucial role in concealing the surface S protein from molecular recognition. The immunomodulatory properties of Glycan-binding proteins (GBPs) like Lectins, build them as an attractive candidates for vaccine adjuvant. Investigations involving the complement system activation by the lectin pathway in COVID-19 and diseases are in need of the hour. The innate immune response involving complement system could have varied biological effects against an array of microbial infections. The advances in glycoprotein style methods especially immunomodulatory action of some lectins are necessary to boost the effectiveness of treatment of COVID-19 and other pandemics.
Service Learning in Philosophical Ethics
Authors: Choe-Smith Chong Un ,   Philosophy Documentation Center
Published: April 2021

Ethics training is becoming increasingly common in pre-professional contexts to address ethical misconduct in business, medicine, science, and other disciplines. These courses are often taught by philosophers. The question is whether such ethics training, which involves philosophical reflection, is effective in cultivating ethical behavior. This paper takes a closer look at the goals of teaching ethics and how our current methods are ineffective in achieving the affective and active goals of teaching ethics. This paper then suggests how experiential learning and, specifically, service learning may be one way forward in achieving these goals. While some pre-professional programs have implemented service learning, the ethics courses offered by philosophers also may be improved by giving students more opportunities to engage their communities through service learning.
A note on identities with derivations in prime rings
Authors: Ur Rehman
Published: April 2021

The present paper's primary purpose is to study the connection between commutativity of rings and the behavior of its derivations in prime rings.
Coefficient estimates for families of bi-univalent functions defined by Ruscheweyh derivative operator
Authors: Bulut Serap , Kareem Wanas
Published: April 2021

The main purpose of this manuscript is to find upper bounds for the second and third Taylor-Maclaurin coefficients for two families of holomorphic and bi-univalent functions associated with Ruscheweyh derivative operator. Further, we point out certain special cases for our results.
Bulgaria and the Ukrainian crisis: National interests and political institutions
Authors: Cholakov Petar
Published: April 2021

The Ukrainian crisis is an arena of geopolitical conflict in which the interests of Russia, NATO and the EU intertwine. It is in this context that the behaviour of Bulgarian political institutions has to be analyzed. In the first section, I explore the reactions and positions of the Bulgarian governments, the main political parties and the presidential institution towards the Ukrainian crisis. In the second part, I highlight the tools used by Russia in order to influence Bulgarian political institutions and processes. The third section traces the measures undertaken by the United States and the EU to neutralize Russia's clout. I defend the view that Sofia needs to be more consistent in fulfilling its commitments to NATO and the EU.
A capital contribution to the Serbian diaspora studies - Vladimir Grečić: Serbian creative intelligence in the diaspora, Matica srpska, Novi Sad, 2019
Authors: Mitrović Ljubiša
Published: April 2021

The paper presents a review of the studies in relation to the matter of external migrations conducted by Professor Vladimir Grečić and, in particular, his latest book Serbian Creative Intelligence in the Diaspora. The conclusion is that the value of this monograph is not only in its scholarly contribution to the perception of this important matter, but also in its relevance to the rational establishment of a strategy and upgrading of Serbia's public policy in the area of home country-diaspora relationship.
Impact of COVID-19 pandemic on the insurance industry
Authors: Jovanović Slobodan
Published: April 2021

In this paper, the author analyses the impact of the COVID-19 pandemic on internal and external aspects of insurance organizations, and particularly on insurance terms and conditions. The introductory part provides general remarks on the impact of the pandemic on community and economy, also defining the subject of the paper. In the second part, the author explores how insurers responded to new working conditions and behaved in relation to their self-organization and to the public and the insured persons. Particular developments in a macroeconomic and political context relating to covering losses from COVID-19 are also analyzed. The author concludes that a certain delay in making the amendments and supplements to the list of communicable diseases was justified, whereas the main characteristic of extended cover for COVID-19 provided by domestic insurers is not the reimbursement of medical treatment costs but the payment of daily allowance and provision of information and particular services. In addition, the author concludes that wordings used to exclude the risk of communicable diseases may create particular dilemmas as to whether a loss event may be considered insured, depending on the circumstances and time of its occurrence, and depending on the provisions of positive legal regulations.
Covid-19 pandemic: Health risks and far-fetching adverse effects on economic and other trends
Authors: Petrović Miloš
Published: April 2021

From the first quarter of 2020, various levels of governments in all parts of the world, Serbia including, have been trying to use restrictive and other measures to restrain the spreading of Covid-19 pandemic and mitigate the adverse effects, with various outcomes. Although its occurrence has actually set a precedent and is ungrateful for forecasts, the second year of the pandemic has confirmed that there will be, in addition to the present, some medium and perhaps long-term economic effects (recovery of the tourism sector, aviation industry and some segments of insurance business is not likely to happen in the coming years). This paper, inter alia, analyses the effects of the pandemic on the roadside assistance insurance in the Republic of Serbia in 2020. Considering the high relevance of the topic, the research relies upon qualitative and quantitative data in a few scientific disciplines, using different types of sources, starting from the electronic databases, through national and international documents and legal acts, to scientific, professional and other articles. The conclusion is that the Covid-19 pandemic trend has, in addition to the economic and social disruptions, spurred the emergence of new transnational challenges that manifest in the political and moral aspects of the process of immunization of the population against the virus, administered in various countries. Moreover, the beginning of the process of immunization is the first milestone in combating the pandemic and its adverse effects on the people and economy.
The restoration of forest ecosystems in the NP 'Fruška Gora' 20 years after the bombing
Authors: Stojšić Vida , Dinić Anka , Grozdanić Đorđe
Published: April 2021

This paper presents the restoration of forest ecosystems in the NP "Fruška gora" 20 years after the bombing, which lasted from April 4 to June 8, 1999. The most frequently bombed sites were: Elektrovojvodina (Iriški venac), Kraljeve stolice, Paragovo, Crveni čot and Dubočaš. The most affected were sessile oak, sessile-hornbeam and beech forests with linden. At the sites Elektrovojvodina, Paragovo and Crveni čot, young oak forests 15-20 years of age have been restored by planting sessile oak and sowing acorns. Beech-linden forests will spontaneously restore, which is indicated by the appearance of young beech seedlings. At the Dubočaš site, in a destroyed forest dug by craters, dense acacia shrubs have been formed. In the sessile forest on the Kraljeve stolice site, the pioneer species Salix caprea and Populus tremula, 15-20 years of age, are in the proces of spontaneous restoration. However, this forest cannot be restored without human intervention.
Composing a vegetation-stand map for the protected area of 'Radan' Nature Park
Authors: Ostojić Dragana , Krsteski Biljana , Stojković Zoran , Petković Ana , Stojiljković Bogosav , Jovanović Ivana , Bosić Tamara
Published: April 2021

Protected areas are one of the priorities for mapping habitats, especially forest habitats, which are dominant in most protected areas of central Serbia, such as "Radan" Nature Park. This paper presents the forest habitat mapping in the protected area of "Radan" NP and the development of vegetation-stand map of the protected area in an effort to examine the methodology of forest habitats mapping in Serbia, which presumes a long term systematic data collection. Although much has been done on the classification of habitats in Serbia, considering both botanical and the forestry approach, the practical application of this knowledge in habitat mapping is still in its infancy, with the exception of longstanding practical work on data collection for Forest Management Plans for the state-owned forests. Data on forest stands in Nature Park "Radan" collected in this manner were essential to developing the vegetation-stand map of "Radan" NP. The results of data processing and harmonization of typology and classification of state-owned forests have been presented in this paper, as well as the analysis of forest habitat types in this protected area. The paper presents the vegetation-stand maps of the state-owned forests in the protected area and of the pilot area of privately owned forests, for which detailed field data collection was necessary. These maps are intended for the management of protected areas and systematic and efficient implementation of protection measures and activities. Habitat mapping in protected areas is a prerequisite for an adequate biodiversity monitoring, as well as for management and sustainable use of natural resources of the protected area.
Metamodeling of NURBS Surfaces for Visual Representation of Hydrodynamic Solutions
Authors: Cuneo Brian J. , Sypniewski Michael J. , Heshiki Zensho , Rosenthal Benjamin J.
Published: April 2021

The present paper discusses the topic that of directional stability and course keeping of fast Throughout early stages of ship design, numerous design variable values must be considered to gather information in an effort to steer decision makers towards optimal designs. The computational speed of design tools often leads engineers to make tradeoffs between solution fidelity and the time it takes to analyze multiple designs with the same tool. Metamodeling allows for instantaneous estimation of higher fidelity solutions for tools with a single value as an output, such as total resistance. However, these methods lack in usefulness when the solution of a design tool is visual in nature, such as the distribution of pressures on a hull. This paper will outline a new method of metamodeling applied to distributed data. While current metamodeling methods are useful in automated design environments, such as optimization algorithms, the method described in this paper allows the designer to be brought back into the design process by providing immediate estimations of design tool outputs that are best interpreted visually. The method works by using Non-Uniform Rational B-Spine (NURBS) curves and surfaces to represent 2 and 3 dimensional outputs of design tools and applying conventional metamodeling methods to the NURBS coefficients. The remainder of this paper will be outlined as follows: first background information will be presented, then the NURBS metamodeling method will be explained in detail, next two example applications will be demonstrated, finally some conclusions will be made.
Autonomous Collision Avoidance Tradespace Analysis for High-Speed Vessels
Authors: Woener Kyle L. , Benjamin Michael R.
Published: April 2021

In this work, a trade space was introduced allowing a weighted combination of a course change and speed change when deviating from the preferred velocity vector in protocol-constrained autonomous collision avoidance algorithms. A novel iterative geometry testing technique was introduced and key evaluation metrics were studied including the introduction of a protocol-compliance metric for collision avoidance scenarios. The performance metric results differed for high-speed vessels indicating a need for parameter tuning specific to high-speed vessels before applying collision avoidance algorithms tested on slower vessels.
Flow-Induced Vibration Characteristics of Lightweight Lifting Bodies in Water
Authors: Chae Eun Jung , Young Yin Lu
Published: April 2021

As interest in maritime applications of lightweight materials increases, understanding the flow-induced vibration characteristics becomes more important to ensure structural safety and to optimize performance and control. The objective of this paper is to investigate the flow-induced vibration characteristics of lightweight lifting bodies in water. The results show that the in-water to in-air natural frequency ratios decrease rapidly as the structure becomes lighter, and the natural frequencies become mode and speed dependent due to changes in the fluid added mass, damping, and disturbing force terms. The fluid damping and stiffness terms are also modified by viscous fluid-structure interaction effects, including changes in the center of pressure, separation, as well as generation and interaction of vortices with body motions. The results also show that the linear potential theory significantly over-predicts the fluid damping for lightweight lifting bodies in water. Hence, care is needed when designing lightweight lifting bodies in water to avoid hydroelastic instability failures, and to avoid unexpected accelerated fatigue, noise, vibration issues.
CFD Simulation of Resistance of Highspeed Trimaran Hullforms
Authors: Son Changhwan , Sahoo Prasanta K. , Aribenchi Vaibhav , Asapana Srikanth
Published: April 2021

This paper attempts to carry out a CFD analysis on total resistance for trimaran hull forms based on established NPL systematic series which are high-speed round bilge hull forms. The resistance of high-speed trimaran hull forms have been determined using ANSYS FLUENT, a CFD software package. A systematic series of round bilge demi-hulls were generated, and their resistance in calm water were determined by using ANSYS FLUENT to briefly examine nature and degree of reliability of ANSYS FLUENT. The primary aim of this investigation is to determine resistance characteristics of slender round bilge trimaran hull forms in the high-speed range corresponding to Froude numbers up to 1.0. Model test results obtained from the paper Molland et al (1994) have been used to verify the efficacy of the CFD analysis. The results obtained from CFD have shown considerable promise and further analysis need to be carried out for accurate determination of resistance in trimaran configuration.
The Design of the “Dynabout” - The Dynaplane Concept Applied to the Design of a More Efficient Outboard Powered Recreational Runabout
Authors: Parkyn Nicholas D.
Published: April 2021

The Dynaplane concept has many real advantages and benefits, but has not enjoyed the acceptance that it deserves. The Dynaplane concept was originally conceived for application to craft over 20ft in length powered by inboard engine with drive leg mounted well forward of transom, a transom mounted rudder and v-shaped stern foil configuration.

The author has revised, revisited and simplified some aspects of the original Dynaplane concept to realize its application to a 16.5ft (5m) outboard powered “runabout” style craft which should appeal to the recreational boating market.

Since research and previous application by Eugene Clement was on larger craft, some data and aspects were extended for applicability to the smaller sized version.

Design software “Dyna_Designer” applicable to Dynaplane was developed and used during the design process. Powering, stern foil configuration, steering and step ventilation were re-worked to reduce complexity. During the design process the author was privileged to have the support of and input from Eugene Clement. The final design documents were made available to Eugene Clement by the author and his responses were positive.

This paper describes some aspects of the development work done to date by the author in realizing a runabout design using the Dynaplane concept.
Improving Cost and Fuel Efficiency of Short Sea Ro-Ro Vessels through More Slender Designs - A Feasibility Study
Authors: Lindstad Haakon , Mørch Hans Jørgen , Sandass Inge
Published: April 2021

Despite the political objective of decreasing road transport and transfer cargo to road and sea, short sea shipping is struggling. There is therefore a need for development of new short sea Ro-Ro vessels which use significantly less fuel per ton transported which can be built at a modest cost. This feasibility study has: First mapped the main characteristics of the current fleet, i.e. dimensions, capacities, installed power and designs speeds; Second investigated alternative combinations of main measurements to enable more slender hull forms which require less power and hence give fuel consumption and fuel cost per transported unit; Third, performed a case study to compare the economic and environmental performance of these slenderer designs, with traditional designs and road only solutions. This study shows the advantage of investigating a large number of alternative dimensions and capacities to identify the designs which reduces cost and fuel consumption. And that the best option is to design and build more slender vessels.
A Life-cycle Cost Analysis of the Application of a Hull Vane to an Offshore Patrol Vessel
Authors: Bouckaert Bruno , Uithof Kasper , van Oossanen Perry , Moerke Niels , Nienhuis Bart , van Bergen Jan
Published: April 2021

The consequences of applying a Hull Vane to a Holland Class 108 m Oceangoing Patrol Vessel of the Royal Netherlands Navy were studied by means of a Computational Fluid Dynamics study using Fine/Marine. The effect on the annual fuel consumption was determined by linking the savings percentages at several speeds to the operational speed profile. This paper demonstrates that - from propulsion point of view - a reduction in total fuel consumption can be achieved of 12.5% if a Hull Vane is installed, along with a small modification to the ship’s hull. At the speed at which most fuel is consumed annually (17.5 knots), the total resistance is reduced by 15.3%. Further operational benefits were quantified, such as a reduction of the vertical accelerations at the helicopter deck when sailing in head waves (-13%), a reduction of the turbulent zone just behind the slipway enabling small craft launch and recovery (from 5 to 2.5 meters), an increased range (from 5,000 nautical miles to 5,850 nautical miles at 15 knots) and an increased top speed (from 21.5 knots to 22.1 knots).
A Theoretical Study of the Optimal Dynaplane Vessel
Authors: Doctors Lawrence J.
Published: April 2021

This paper is concerned with slamming on ships, with particular emphasis on bow flare slamming. An efficient numerical method presented by Hermundstad and Moan (2007) is briefly described, and a summary of previous and new validation results is given. This includes a bow section dropped onto calm water, a 120 m RoRo ship at 20 knots, a 290 m cruise ship at low speed and an FPSO at zero speed. Predictions of slam-induced local stresses by combined slamming and FE-analysis are validated for an aluminum section dropped onto calm water. Based on the experience with the different cases, some general re marks are made with respect to the applicability of the method, the importance of various physical effects and the need for further work.
USCG Patrol Craft Hydrodynamic Fuel Efficiency Improvements
Authors: Savander Brant R. , Willis Malcolm E. , Stambaugh Karl A. , Cox Kelley A.
Published: April 2021

A computational analysis program, conducted at full scale, has been completed on the USCG Fast Response Cutter (FRC) to evaluate how appendage and propeller redesign affects calm water powering performance and erosive cavitation onset. Aft working forward, the geometric variations considered included: addition of a stern flap, wake adapted rudder redesign, propeller design refinement, wake adapted skeg redesign, and redesign of the spray rail system. The first activity was to use a wake alignment procedure to redesign the current rudder in an effort to improve the rudder drag characteristics and minimize or eliminate rudder cavitation. The wake aligned redesign eliminated rudder cavitation over the entire speed range, and decreased total drag by 6% at flank speed. Replacement of only the current rudders with the wake aligned redesign is predicted to increase flank speed from 28.9 knots to 29.4 knots. The stern flap and spray rail efforts followed the historical guidance of similar work performed on the USCG Island Class patrol boats, as documented in Cusanelli and Barry (2002). Following the geometric guidance of the Island Class stern flaps the final recommended stern flap for the FRC results in a brake power demand reduction of 15%. The Island Class achieved a 12% reduction in required brake power at similar speeds. The combination of the new stern flap, wake adapted rudders, current propeller, current skegs, and new spray rail yielded an increase in flank speed from 28.9 to 31.4 knots. Skeg redesign resulted in a 30% decrease in the magnitude of the radiated pressure pulse amplitudes experienced in the propeller tunnel above the propeller. The redesign of the skeg did not affect the propeller behind efficiency. Modification of the current propeller geometry was the final redesign task. The final system, which included the new stern flap, wake aligned rudders, redesigned propeller, wake aligned skegs, and new spray rail system decreased power by 18.6% at the prior 28.9 knot flank speed of FRC. The new flank speed, with the final system, has increased to 32.9 knots in the full load, end of service life condition. The combined effect of all redesign activities reveals an annual fuel consumption savings of 24,000 gallons per vessel per year, which corresponds to a 13.6% savings when compared to the original as-built system. Assuming a fuel cost of $4 per gallon, the annual cost savings per vessel per year equals $96,000. This savings extrapolated over a 58 ship fleet equates to $5.5 million in savings per year for the class. This saving per year yields a savings of $110 million for the 20-year operating life of the 58-ship class.
Numerical Study on Performance of Surface Piercing Propeller using RANS Approach
Authors: Himei Kohei , Yamaguchi Hajime
Published: April 2021

Surface Piercing Propeller (SPP) can achieve high propulsive efficiency on high-speed vessels planing to reduce the frictional resistance of hull. It has the characteristic blade section and works partially submerged condition. The blades repeat entry to and exit from the water free surface and the suction sides and trailing edge of blades are exposed to ventilated cavitation while they are under the water. And interface near SPP is severely deformed by the high rotating blades. This working condition of SPP, therefore, makes it hard that propeller open characteristics are estimated with high reliability. Because SPP is unusual propeller having above difficulty of the performance estimation, the studies for SPP are few compared with large sized propellers for merchant ships. Although the various model tests had been carried out to understand the physical phenomena around various SPPs and their effects on propeller performances, they were not universal approach with standardized test conditions and propeller shape, as mentioned in 23th ITTC report and recommendation (2002). In applying the conventional calculation based on potential theory to SPP, there are many difficulties to model the physical phenomena theoretically. In calculations by Furuya (1984, 1985), thickness of blade and ventilated cavitation were non-consideration, and it was assumed that the suction side of the blade was fully ventilated in the water. In calculations by Young and Kinnas (2001), the interface deformation near SPP was not modeled theoretically. Therefore, they attributed the difference from experimental results to the effect of incompleteness of numerical modeling. On the other hand, CFD analysis can treat the effects of physical phenomena including thick ventilated cavitation and the sharp deformation of interface around SPP. In addition, the characteristic blade shape is modeled accurately without the geometric limitation in CFD. In this paper, typical SPP with experimental results open to the public is analyzed by CFD-RANS approach using Volume of Fluid (VOF) method based on interface-capturing algorithm at wide range of propeller advance coefficient J. Regarding propeller open characteristics, the 6-component force/moment fluctuations by blade rotations, and ventilation patterns, analyses results are compared with measured values. Moreover, the results of simulations in various Froude numbers and Weber numbers are evaluated whether their effects were negligible when they are sufficiently high, in the same manner as the results found by the other’s experimental studies (Shiba, 1953; Brandt, 1973).
Numerical Modeling of Hydrodynamic Impact and Local Slamming Effects
Authors: Mohtat Ali , Challa Ravi , Yim Solomon C. , Judge Carolyn Q.
Published: April 2021

Numerical simulation and prediction of short duration hydrodynamic impact loading on a generic wedge impacting a water free-surface is investigated. The fluid field is modeled using a finite element (FE) based arbitrary Lagrangian-Eulerian (ALE) formulation and the structure is modeled using a standard Lagrangian FE approximation. Validation of the numerical method against experimental test data and closed form analytical solutions shows that the ALE-FE/FE continuum approach captures the impact behavior accurately. A detailed sensitivity analysis is conducted to study the role of air compressibility, deadrise angle, and impact velocity in estimation of maximum impact pressures. The pressure field is found to be insensitive to air compressibility effect for a wide range of impact velocities and deadrise angles. A semi-analytical prediction model is developed for estimation of maximum impact pressures that correlates deadrise angle, impact velocity, and a nonlinear interaction term that couples hydrodynamic effects between these parameters. The numerical method is also used to examine the intrinsic physics of water impact on a high-speed planing hull with the goal of predicting slamming loads and resulting motions.
Lessons to be Learned from the Study of Indigenous Craft
Authors: Noble Peter G.
Published: April 2021

By looking backwards we can often discover solutions that will allow forward progress. We see in the bible the idea that history repeats itself: What has been will be again, what has been done will be done again; there is nothing new under the sun. Ecclesiastes 1:9 But the author subscribes to the idea put forward by the American humorist, Mark Twain: History doesn’t repeat itself, but sometimes it rhymes. The design and construction of water-borne craft using “scientific” methods is a relatively recent development in the context of the whole history of that activity, and is by no means universally applied even today Many traditional craft in current service still rely on the process akin to natural selection, as proposed by Darwin, that is, it is not the strongest, most intelligent nor the fittest that survive but those that best adapt. And the evolutionary process continues today. From Bangkok water taxis with “long-tail” propulsion systems, and from Haitian fishing boats with high performance new sails to whaling umiaks in NW Alaska covered with tensioned membrane skins made from walrus hide and equipped with outboard motors, there can be value in studying the design, construction and operational approaches of these craft. Such consideration can lead to insights for the modern naval architect. A number of well-researched publications (Tapan Adney, 1964) and (Haddon, 1975) give a wealth of information on indigenous craft. Sturgeon Nose Canoe USN ZUMWALT Class Destroyer. Noble Lessons to be learned from the study of indigenous craft 2 Lessons such as optimizing weight/strength ratios, minimizing resistance, utilizing materials in clever ways, developing repairable structures etc., can all be learned from the study of indigenous craft. The sense of continuity with a living past obtained by the study of the work of previous generations of designers and builders, realizing that many current problems were their problems too, is both valuable and satisfying. That said, not all examples given in this paper can be directly linked to designers actively seeking out past developments. Some examples have occurred by coincidence, some by accident and some by unwitting “reinvention of the wheel”. Many “new” ideas, however, have been tried before and it is very often possible to test a new idea against past experience. This paper builds on previous ethno-technical study, (Noble 1994) describing the author’s experience in this field and uses a number of specific examples to illustrate the premise.
Seakeeping Analysis of a SWATH-type Trimaran Using Potential Flow
Authors: Onas Adrian S. , Falls Jaye , Stojanovic Ivan
Published: April 2021

Potential flow methods tend to over-predict ship motions, especially the lightly damped, viscous effect dominated modes, such as roll. For SWATH ships, it is not uncommon to also over-predict heaving and pitching motions because of the strong viscous effects dominating the energy dissipation mechanism due to significant vortex shedding generated by the submerged hull(s). Care should be taken whenever such viscous effect become a significant part the total damping. Such fact appears to render the potential flow approach less useful when analyzing the restored response of SWATH ships compared to conventional ships, such as monohulls. The Atlantic Center for Innovative Design and Control of Small Ships (ACCeSS), under ONR sponsorship, has been studying a hybrid trimaran hull form with a small waterplane area center hull, so-called the Tri-SWACH. Extensive towing tank testing has been undertaken with the intent to characterize the behavior of the Tri-SWACH and to provide data for the verification and validation of predictive tools. For previous work, the scale models of the Tri-SWACH were identical below the waterline, but lacked any realistic cross-deck structure above the waterline. This setup is ideal to capture the nonlinear ship motion behavior in future studies since the scale and numerical models were made identical above and below the waterline, and include a representative cross-deck. For the current study, the linear transfer functions and short-term statistics are obtained using the potential flow code WASIM, and are partially validated using experimental results obtained from the United States Naval Academy and Stevens Institute of Technology.
Recent Developments in Ride Control
Authors: Haywood Alan J. , Schaub Benton H. , Pappas Chris M.
Published: April 2021

The use of ride control systems on high speed vessels has become the norm within many industries, producing better seakeeping that in turn provides a more comfortable and operationally effective vessel. Commercial ferry designers have been at the forefront of adoption of new technologies notably with early adoption of T-foils and interceptors. These devices have been taken up by others, for example offshore crew boats and frontline naval warships. The range of vessel types has also expanded with more industries adopting different hull designs including catamarans and trimarans. Ride control systems have developed alongside innovative designers producing for example combined lifting foil and ride control systems, lifting T-foil systems, retractable T-foils. This paper will review the different ride control devices including fins, trim tabs, interceptors, T-foils (including retractable T-foils) and lifting foils. As well as technical aspects, the discussion will consider costs, ease of installation, operational and maintenance requirements and material choice. Extensive examples from a wide range of industries will be presented. By the end of the talk, delegates will have a broad understanding of the options available to them in improving the seakeeping of their vessels.
Improving Seaplane Seakeeping through the Use of Amortized Floats
Authors: Varyukhin Anton N. , Veselov Vladimir V. , Ovdienko Maxim A. , Arilin Alexandr V. , Dikiy Sergey V.
Published: April 2021

Seaworthiness characteristics are one of the key conditions for the success of the seaplane. So the improvement of these characteristics is an important task. It was suggested that the using of amortized floats could improve the seaworthiness characteristics of seaplane. For this purpose series of experiments were carried out and mathematical model was developed.
Development and Research of Power Electronic Converters for Adjustable Transformers
Authors:   , Priedītis Mārcis
Published: April 2021

The Thesis is devoted to research of for injection transformer (IT) electronic control methods for IT which are based on high-frequency AC pulse regulation in electrical circuits with the purpose to change AC electrical parameters (amplitude, rms value, phase shift) in IT control circuits. As such pulse control methods of AC systems have been rarely studied, the work pays more attention to the in-depth study of these methods, developing both calculation methods based on the basic harmonic determination of modulated AC and AC and their effect on the electrical load circuit operating parameters. In this way unipolar, bipolar and interphase modulation systems using bi-directional electronic semiconductor switches have been studied. A calculation methodology for the LC filtering system of modulated voltage signals has been developed which is based on the above-mentioned basic harmonic influence method. The transmission of such modulated regulatory influence signals through the IT system and the possibilities to provide an extended influence on the possibility of changes in IT load parameters are also considered. The paper discusses the possibilities to create new modulation-based electronic control and conversion systems for various AC applications, such as single-phase-two-phase and single-phase-three-phase voltage splitting systems. All the proposed technical solutions have been tested with computer models, and the results agree well with the theoretical calculations, which allows us to consider that the technical proposals are applicable in practice.
Development of Operation and Diagnostic Algorithm Complex for Technical Condition Assessment of Power Transformers in Permissible Risk Circumstances
Authors:   , Poišs Gints
Published: April 2021

A power transformer is a key unit in the transmission system, and its cut-off can impact both consumers and the general stability of the system. Therefore, it is an important tool for processing the operational and technical condition data to quantify them as the technical condition index (TCI). Based on the technical condition of the power transformer, the TCI enables objective and reasoned decisions on the future investments related to replacement or repairs of transformers. Thus, by using the TCI, the service life of the transformer can be safely extended, since the identified risks have been recognized and are being followed-up. The TCI method is useful for a power transformer park, because it allows easy identification of transformers that require most attention. A crucial precondition for this method is data availability, diversity, and regularity or frequency of data collection. These features (preconditions) may vary in different power transmission systems, and it creates the necessity for a tailored approach. The present Doctoral Thesis studies the diagnostic methods used in the transmission system in Latvia and the results thereof. Thus, it takes advantage of an already existing data set and flow to develop a TCI-based complex of algorithms for determining the risk level of high-power transformers in acceptable risk conditions.
Why flies look to the skies
Authors: Heinze Stanley
Published: April 2021

Fruit flies rely on an intricate neural pathway to process polarized light signals in order to inform their internal compass about the position of the Sun.
TP53 mutation and MET amplification in circulating tumor DNA analysis predict disease progression in patients with advanced gastric cancer
Authors: Li Jia , Li Zhaoyan , Ding Yajie , Xu Yan , Zhu Xiaohong , Cao Nida , Huang Chen , Qin Mengmeng , Liu Feng , Zhao Aiguang
Published: April 2021

Background

Gastric cancer (GC) is a heterogeneous disease that encompasses various molecular subtypes. The molecular mutation characteristics of circulating tumor DNA (ctDNA) in advanced gastric cancer (AGC), especially the clinical utility of TP53 mutation and MET amplification in ctDNA need to be further explored.

Objectives

The aim of this study was mainly to assess the clinical utility of TP53 mutation and MET amplification in ctDNA as biomarkers for monitoring disease progression of AGC.

Patients and Methods

We used multigene NGS-panel technology to study the characteristics of ctDNA gene mutations and screen the key mutant genes in AGC patients. The Kaplan-Meier method was used to calculate the survival probability and log-rank test was used to compare the survival curves of TP53 mutation and MET amplification in ctDNA of AGC patients. The survival time was set from the blood test time to the follow-up time to observe the relationship between the monitoring index and tumor prognosis.

Results

We performed mutation detection on ctDNA in 23 patients with AGC and identified the top 20 mutant genes. The five most frequently mutated genes were TP53 (55%), EGFR (20%), ERBB2 (20%), MET (15%) and APC (10%). TP53 was the most common mutated gene (55%) and MET had a higher frequency of mutations (15%) in our study. Kaplan-Meier analysis showed that patients with TP53 mutant in ctDNA had shorter overall survival (OS) than these with TP53 wild (P < 0.001). The Allele frequency (AF) of TP53 mutations in patient number 1 was higher in the second time (0.94%) than in the first time (0.36%); the AF of TP53 mutations in patient number 16 was from scratch (0∼0.26%). In addition, the AF of TP53 mutations in patients who survive was relatively low (P = 0.047). Simultaneously, Kaplan-Meier analysis showed that patients with MET amplification also had shorter OS than these with MET without amplification (P < 0.001).

Conclusion

TP53 and MET are the two common frequently mutant genes in ctDNA of AGC patients.TP53 mutation and MET amplification in ctDNA could predict disease progression of AGC patients.
Optimizing speleological monitoring efforts: insights from long-term data for tropical iron caves
Authors: Trevelin Leonardo Carreira , Simões Matheus Henrique , Prous Xavier , Pietrobon Thadeu , Brandi Iuri Viana , Jaffé Rodolfo
Published: April 2021

Understanding the factors underpinning species abundance patterns in space and time is essential to implement effective cave conservation actions. Yet, the methods employed to monitor cave biodiversity still lack standardization, and no quantitative assessment has yet tried to optimize the amount and type of information required to efficiently identify disturbances in cave ecosystems. Using a comprehensive monitoring dataset for tropical iron caves, comprising abundance measurements for 33 target taxa surveyed across 95 caves along four years, here we provide the first evidence-based recommendations to optimize monitoring programs seeking to follow target species abundance through time. We found that seasonality did not influence the ability to detect temporal abundance trends. However, in most species, abundance estimates assessed during the dry season resulted in a more accurate detection of temporal abundance trends, and at least three surveys were required to identify global temporal abundance trends. Finally, we identified a subset of species that could potentially serve as short-term disturbance indicators. Results suggest that iron cave monitoring programs implemented in our study region could focus sampling efforts in the dry season, where detectability of target species is higher, while assuring data collection for at least three years. More generally, our study reveals the importance of long-term cave monitoring programs for detecting possible disturbances in subterranean ecosystems, and for using the generated information to optimize future monitoring efforts.
Intraspecific morphological variation ofBellidiastrum michelii(Asteraceae) along a 1,155 m elevation gradient in the Tatra Mountains
Authors: Kiełtyk Piotr
Published: April 2021

Plant species that inhabit large elevation gradients in mountain regions are exposed to different environmental conditions. These different conditions may influence plant morphology via plastic responses and/or via genetic adaptation to the local environment. In this study, morphological variation was examined forBellidiastrum micheliiCass. (Asteraceae) plants growing along a 1,155 m elevation gradient in the Tatra Mountains in Central Europe. The aim was to contribute to gaining a better understanding of within-species morphological variation in a mountain species across elevation gradients. Twelve morphological traits, which were measured for 340 plants collected from 34 sites, were plotted against elevation using Generalised Additive Models. Significant variation inB. micheliimorphology was found across the elevation gradient. Plant size, in the form of plant height, total aboveground mass and total leaf mass, decreased significantly with increasing elevation. Similarly, floral traits, such as flower head mass, total flower mass, individual flower mass, flower head diameter and ligulate and tubular flower length, also decreased significantly with increasing elevation. However, the changes in these floral traits were not as large as those observed for plant size traits. Interestingly, the number of flowers produced by the plant, both ligulate and tubular, did not change across the studied elevation gradient. In this study, elevation was found to be an important gradient across which significant intraspecific morphological variation occurred in a mountain plant. These morphological changes may have occurred in response to various abiotic and biotic factors that change along elevation gradients.
Interacción entre demanda, proceso y competencia: un análisis cognitivo del constructo del test de comprensión lectora de ELE para sinohablantes
Authors:   Universidad de Estudios Internacionales de Shanghai (China), Ge Li
Published: April 2021

En el presente trabajo, se adopta la triangulación como método de investigación para observar las relaciones interactivas entre las demandas, los procesos cognitivos y las demandas del test de comprensión lectora. Mediante el análisis factorial exploratorio y el análisis de protocolos de pensamiento en voz alta de un grupo de aprendientes sinohablantes de español, descubrimos la convergencia entre los resultados cuantitativos y cualitativos y, en consecuencia, verificamos el supuesto de que los procesos cognitivos pueden servir de indicador de competencia para la validación del constructo, con lo que ofrecemos como contribución a los evaluadores una potencial metodología cognitiva de validar el constructo del test de comprensión lectora.