bluuebunny/crossref_metadata_2025 huggingface dataset:
DNA barcoding of exuviae for species identification of Central European damselflies and dragonflies (Insecta: Odonata)
Authors: Sittenthaler Marcia , Fischer Iris , Chovanec Andreas , Koblmüller Stephan , Macek Oliver , Sattmann Helmut , Szucsich Nikolaus , Zangl Lukas , Haring Elisabeth
Published: March 2023

Monitoring of odonates has become an important instrument for ecological status assessment of (semi-)aquatic habitats. Besides information on presence and abundance, knowledge about a species´ autochthony at the surveyed waterbody is a significant information within the assessment process. Here, the finding of exuviae represents the ultimate proof of successful reproduction. Although feasible for most odonate species, morphological identification of exuviae is often time consuming, as it relies on small, fragile structures. To facilitate species identification of exuviae, a DNA barcoding approach was developed, including (1) non-destructive extraction of DNA using whole exuviae or their tracheal tubes, and (2) primer systems for long (< 600 bp) and short (< 200 bp) CO1 fragments. A total of 85 exuviae from 33 species were analysed and compared to results of morphological identification. Additionally, factors potentially influencing DNA quality and quantity, as well as PCR and sequencing success were investigated. Eighty-two exuviae matched the morphologically identified genus, and 60 matched at species level. Of the 33 species present in the data set, 82% could be identified to species level via DNA barcoding. The results show how DNA-based approaches can support fast and accurate species identification and therefore enhance monitoring of an ecologically important taxonomic group, with high relevance for conservation and habitat restoration. Moreover, the use of exuviae as DNA resource once more shows that non-invasive sampling offers great potential for molecular species identification, which is essential when studying rare and endangered species.

Implications for insect conservation

Our results show how molecular tools, here DNA barcoding of odonate exuviae, can support species monitoring without the need of catching individuals, harming, or even killing them. Obtaining DNA from non-invasive sources can thus be a direct advantage to the conservation of insects, especially when dealing with rare and endangered species and/or populations. Using the example of odonates as bioindicator organisms for aquatic and semi-aquatic habitats, we highlight the importance of non-invasive genetic approaches for population studies and monitoring of insect species and/or species communities for ecosystem assessments and conservation management.
An insight into the suitability of magnesium ion-conducting biodegradable methyl cellulose solid polymer electrolyte film in energy storage devices
Authors: Koliyoor Jayalakshmi , Ismayil  , Hegde Shreedatta , Sanjeev Ganesh , Murari Mudiyaru Subrahmanya
Published: March 2023

Biodegradable solid polymer electrolyte films based on methyl cellulose and magnesium acetate tetrahydrate [Mg(CH3COO)2.4H2O] are prepared using the conventional solution casting technique. Structural analysis of the electrolyte films confirmed the complexation of salt with the polymer matrix. The incorporation of salt into the polymer matrix resulted in the enhancement of the amorphousness of the matrix. The thermal properties of the electrolyte film are analyzed with the help of DSC and TGA thermograms. Impedance analysis of the films indicates the enhancement of the electrical conductivity of the system. The maximum room temperature ionic conductivity (2.61 × 10−5 S/cm) was observed for the 25wt% salt-doped sample. The highest conducting electrolyte system has an Electrochemical Stability Window (ESW) of 3.47 V. In the current work, a primary battery was assembled using the highest conducting polymer electrolyte system, and its open-circuit potential and discharge characteristics were also investigated.

Graphical abstract
Biomimetic vascular tissue engineering by decellularized scaffold and concurrent cyclic tensile and shear stresses
Authors: Omid Hamed , Abdollahi Sorosh , Bonakdar Shahin , Haghighipour Nooshin , Shokrgozar Mohammad Ali , Mohammadi Javad
Published: March 2023

Decellularization by chemical approaches has harmful effects on extracellular matrix (ECM) proteins, and damages lots of functional peptides and biomolecules present in the ultrastructure. In this study, we employed a combination of chemical and physical decellularization methods to overcome these disadvantages. The induced osmotic pressure by hypertonic/hypotonic solutions dissociated and removed most of cellular membranes significantly without any detergent or chemical agent. In total, 0.025% trypsin solution was found adequate to remove the remaining debrides, and ultimately 1% Triton X-100 was utilized for final cleansing. In addition, conducting all the decellularization processes at 4 °C yielded an ECM with least damages in the ultrastructure which could be inferred by close mechanical strength and swelling ratio to the native vessel, and high quality and quantity of cell attachment, migration and proliferation which were examined by optical microscopy and scanning electron microscopy (SEM) of the histology samples. Moreover, the obtained biological scaffold (BS) had no cytotoxicity according to the MTT assay, and this scaffold is storable at −20 °C. Employing bioreactor for concurrent cyclic tensile and shear stresses improved the cell migration into pores of the BS and made the cells and the scaffold compact in analogous to native tissue. As opening angle test showed by decellularizing of the blood vessel, the residual stress dropped significantly which revealed the role of cells in the amount of induced stress in the structure. However, intact and healthy ECM explicitly recovered upon recellularization and beat the initial residual stress of the native tissue. The tensile test of the blood vessels in longitudinal and radial directions revealed orthotropic behavior which can be explained by collagen fibers direction in the ECM. Furthermore, by the three regions of the stress–strain curve can be elucidated the roles of cells, elastin and collagen fibers in mechanical behavior of the vascular tissues.

Graphical Abstract
Varieties of Self-Reference in Metamathematics
Authors: Grabmayr Balthasar , Halbach Volker , Ye Lingyuan
Published: March 2023

This paper investigates the conditions under which diagonal sentences can be taken to constitute paradigmatic cases of self-reference. We put forward well-motivated constraints on the diagonal operator and the coding apparatus which separate paradigmatic self-referential sentences, for instance obtained via Gödel’s diagonalization method, from accidental diagonal sentences. In particular, we show that these constraints successfully exclude refutable Henkin sentences, as constructed by Kreisel.
Refining neural network predictions using background knowledge
Authors: Daniele Alessandro , van Krieken Emile , Serafini Luciano , van Harmelen Frank
Published: March 2023

Recent work has shown learning systems can use logical background knowledge to compensate for a lack of labeled training data. Many methods work by creating a loss function that encodes this knowledge. However, often the logic is discarded after training, even if it is still helpful at test time. Instead, we ensure neural network predictions satisfy the knowledge by refining the predictions with an extra computation step. We introduce differentiable refinement functions that find a corrected prediction close to the original prediction. We study how to effectively and efficiently compute these refinement functions. Using a new algorithm called iterative local refinement (ILR), we combine refinement functions to find refined predictions for logical formulas of any complexity. ILR finds refinements on complex SAT formulas in significantly fewer iterations and frequently finds solutions where gradient descent can not. Finally, ILR produces competitive results in the MNIST addition task.
Use of Cellular-Enabled Remote Patient Monitoring Device for Hypertension Management in Pregnant Women: A Feasibility Study
Authors: D. Jones Rebecca , Allison M. Kathryn , Moody Heather , Peng Cheng , Eswaran Hari
Published: March 2023

Introduction

Hypertension affects 5–10% of pregnancies in the United States. Chronic hypertension during pregnancy can have a significant impact on maternal and neonatal outcomes, especially in rural populations. Pregnancies complicated by hypertension are currently managed through frequent clinic visits or extended hospital stays. Cellular-enabled remote patient monitoring devices provide an alternative treatment method for women in rural areas.

Research Aim

This study aimed to measure the feasibility of and patient satisfaction with using an integrated model of cellular-enabled remote patient monitoring devices for blood pressure supported by a 24/7 nurse call center.

Methods

In a mixed methods pilot study, twelve women with chronic hypertension during pregnancy were given cellular-enabled BodyTrace™ blood pressure cuffs and weight scales. Participants’ blood pressures were continuously monitored by a nurse call center. Participants completed a survey and a brief semi-structured interview after two weeks.

Results

Participants scored low on stress and anxiety with mean scores of 5.45 (SD = 3.56) and 8.09 (SD 3.62), respectively. Participants scored high on behavioral intention, system usability, and perceived benefits with mean scores of 8.73 (SD = 2.53), 75.91 (SD = 23.70), and 19.64 (SD = 5.92), respectively. Participants perceived benefits to using the device, including increased monitoring by health professionals, increased self-awareness, decreased number of clinic visits, and convenience of use. Perceived disadvantages included higher readings when compared to clinical readings.

Discussion

Cellular-enabled remote patient monitoring devices for blood pressure are a valuable tool for managing treatment of pregnancies complicated by hypertension.
On the selection of a proper connection in describing the dynamics of constrained mechanical systems
Authors: Natsiavas S. , Passas P. , Tzaferis K.
Published: March 2023

This study is focused on a critical issue related to the direct and consistent application of Newton’s law of motion to a special but large class of mechanical systems, involving equality motion constraints. For these systems, it is advantageous to employ the general analytical dynamics framework, where their motion is represented by a curve on a non-flat configuration manifold. The geometric properties of this manifold, providing the information needed for setting up the equations of motion of the system examined, are fully determined by two mathematical entities. The first of them is the metric tensor, whose components at each point of the manifold are obtained by considering the kinetic energy of the system. The second geometric entity is known as the connection of the manifold. In dynamics, the components of the connection are established by using the set of the motion constraints imposed on the original system and provide the torsion and curvature properties of the manifold. Despite its critical role in the dynamics of constrained systems, the significance of the connection has not been investigated yet at a sufficient level in the current engineering literature. The main objective of the present work is to first provide a systematic way for selecting this geometric entity and then illustrate its role and importance in describing the dynamics of constrained systems.
Evolution of Multidimensional Poverty in Crisis-Ridden Mozambique
Authors: Egger Eva-Maria , Salvucci Vincenzo , Tarp Finn
Published: March 2023

Mozambique experienced important reductions in the poverty rate until recently, before two major natural disasters hit, an armed insurgency stroke in the northern province of Cabo Delgado, and the country started suffering from a hidden debt crisis with associated economic slowdown. As the last available national household expenditure survey is from 2014/15, just before these crises started unfolding, there is need for a poverty assessment based on alternative data sources. We study the evolution of multidimensional poverty in Mozambique using survey data from the Demographic and Health Surveys (DHS). Using both the standard Alkire–Foster multidimensional poverty index and the first-order dominance (FOD) method, we find that the multidimensional poverty reduction trend observed between 2009–11 and 2015 halted between 2015 and 2018. Meanwhile, the number of poor people increased, mainly in rural areas and in the central provinces. Importantly, the poorest provinces did not improve their rankings over time, and between 2015 and 2018, no progress took place for most areas and provinces, as measured by the FOD approach.
The fallow deer Dama celiae sp. nov. with two-pointed antlers from the Middle Pleistocene of Madrid, a contemporary of humans with Acheulean technology
Authors: van der Made Jan , Rodríguez-Alba Juan José , Martos Juan Antonio , Gamarra Jesús , Rubio-Jara Susana , Panera Joaquín , Yravedra José
Published: March 2023

We describe fossils of a new species of fallow deer, Dama celiae. It is the end member of the lineage Dama farnetensis–D. vallonnetensis–D. roberti–D. celiae, which reduced the number of points of the antler from four to two, while the parallel lineage leading to the living fallow deer evolved more complex and palmate antlers. The fossils are from localities Pedro Jaro I and Orcasitas in the + 25–30-m terrace of the Manzanares river, which is correlated to MIS9 (337–300 ka) and which also yielded fossils of Megaloceros matritensis, a recently named species, end member of a lineage that survived longer than previously believed. A younger terrace of the Manzanares yielded remains of Haploidoceros, a rare deer known from two older localities in southern France and one younger locality in Spain. So many rare deer species in this valley indicates either endemism and a very special environment or that the record of fossil deer is much less known than generally assumed. Until recently, the European Middle Pleistocene record of deer had only one middle-sized species at a time. Now, it appears that there were up to three contemporaneous species of the size of a fallow deer. Acheulean lithic assemblages have been documented from the same sites as Dama celiae. This species was contemporaneous to Neanderthals with Acheulean culture. Cut marks suggest that it was consumed by them and probably was hunted.
Examining how perceptions of ready children and diversity shape a teacher’s use of the funds of knowledge approach
Authors: Kim Jiwon
Published: March 2023

This study examined how and to what extent a prekindergarten teacher’s perceptions of ready children and diversity—which are influenced by broader societal culture—influence their abilities and ways of incorporating children’s funds of knowledge into their practice. The methodology used was based on a descriptive case study of a teacher, Linda, who participated in a two-year professional development (PD) program that focused on using funds of knowledge in culturally and developmentally responsive early mathematics pedagogy. How Linda incorporated children’s funds of knowledge when teaching mathematics was closely linked with her notions of the prototypical ready children and her essentialized understanding of culture and diversity. Findings suggest the importance of asset-oriented perspectives of each child and family and attention to cultural practices when learning funds of knowledge to raise teachers’ sensitivity toward and use of children’s funds of knowledge to enrich children’s learning.
More Bang for Your Buck: Best-Practice Recommendations for Designing, Implementing, and Evaluating Job Creation Studies
Authors: Bernal-Turnes Paloma , Ernst Ricardo
Published: March 2023

This paper discusses the application of robust experimental research methodologies that help to provide a better understanding of the mechanisms of the Theory of Change, for which training programs and/or matching grants improve job creation in micro, small, and medium-sized enterprises (MSMEs and SMEs). The literature on both interventions, such as training and matching grants, recognizes methodological flaws that hamper achieving enough statistical evidence to test the aforementioned Theory of Change. A better understanding of the interventions and the mechanisms to create jobs has become critical to ensure the resurgence of the global economy after the COVID-19 pandemic and to face the threat of the upcoming industrial revolution. This paper proposes seven methodological meliorations in impact evaluation that will help to set improvements alongside the full process of a project: designing superior policies and programs, implementing projects, supporting the finer assessment of interventions, and establishing the subsequent advancement of science in testing solutions for job creation.
Knowledge mapping analysis of the track and hotspot of water lubrication: A scientometrics review
Authors: Xu Runzhou , Wu Defa , Wang Zhenyao , Deng Yipan , Cheng Qian , Pang Hao , Wei Wenshu , Liu Yinshui
Published: March 2023

With the enhancement of environmental protection awareness of the international community and the continuous promotion of green and sustainable development of manufacturing industry, water lubrication instead of mineral oil has become the future development trend due to its green, pollution-free, clean, safe, and sustainable advantages especially in ships, marine, coal mining, and other fields. In recent years, with the rapid development of water lubrication research, significant progress has been made in related research knowledge domain and discipline. A systematic and extensive assessment of water lubrication research has become increasingly important. The objective of this research is to reveal the research status, research hotspots, and development trends in the field of water lubrication. Therefore, CiteSpace was used to conduct a systematic bibliometric and scientometrical analysis of 1,792 publications from Web of Science core collection database (1997–2021). The results show that China and USA are the most productive countries in the field of water lubrication and have made outstanding contributions. Through the analysis of hot key words and co-citation references, this paper reviews the research status of water lubrication in three aspects: (1) lubricating medium modification; (2) material preparation; (3) surface optimization. It has become a research hotspot to promote the superlubricity contact interface and the application of nanotechnology. The results of this study can make a significant contribution to the development of water lubrication by providing a comprehensive understanding of the research status and research hotspots in this field. Personal understanding and discussion of research hotspots and research status are expected to provide insights into future research trends. In addition, this study will provide valuable references and guidelines for researchers who are interested in this field.
Current-carrying friction in carbon coated ball bearing
Authors: Xue Peidong , Chen Cheng , Fan Xue , Diao Dongfeng
Published: March 2023

In this work, we proposed a method for coating the whole surfaces of bearing balls uniformly by carbon film with a rotatable ball clamp. We studied the carbon/carbon friction with a self-designed current-carrying ball bearing friction test system. A notable and instant friction force drop of 28% and significant carbon film wear alleviation were found when currents were applied. By using TEM-, SEM-, and EDS-analysis, special carbon stacks with a mixture of large wear particles and oxide were found in the wear areas under current applied condition. We elucidated the current-carrying friction mechanisms as follows: (1) wear particles formation; (2) wear particles charged by tribomicroplasma; (3) formation of surface passivated carbon stacks under electric force; (4) sliding between passivated carbon surfaces. This work may facilitate the development of novel solid-lubricated ball bearings and lay some foundations for current-carrying rolling friction.
Transient temperature characteristics of friction clutch disc considering thermal contact conductance under sliding conditions
Authors: Liu Yuwei , Sun Yuanzhi , Gao Ziyin , Ye Fuhao , Tang Pei
Published: March 2023

High temperatures are generated due to the sliding contacts between the rubbing surfaces of the friction clutch system. In this work, by considering the effective thermal contact conductance under sliding conditions, a simulation model of a two-dimensional transient temperature field of the clutch disc was developed. A numerical solution to obtain the surface temperature at different radii was presented based on the finite difference method. Compared with the experimental data, the proposed model for estimating the surface temperature is more accurate than the conventional prediction method. The results showed that the errors of the calculated temperatures at radii of 114 and 106 mm have obviously reduced by 12.98% and 12.60%, respectively. In addition, the influences of pressure and relative speed on the surface temperature were investigated. The temperature increases with the increase of the relative speed and pressure during the sliding period, and there is an interaction effect between pressure and speed on the surface temperature rise.
Deformation- and rupture-controlled friction between PDMS and a nanometer-scale SiOx single-asperity
Authors: Caron Arnaud
Published: March 2023

This work investigates the friction between polydimethylsiloxane (PDMS) and silicon oxide (SiOx) in single asperity sliding contact by atomic force microscopy (AFM). Two friction dependences on the normal force are identified: a tensile regime and a compressive regime of normal forces. In the compressive regime, friction is governed by the shear deformation and rupture of junctions between PDMS and SiOx. In this case, the shear strength τ ≈ 10 MPa is comparable with the cohesive strength of PDMS under compressive loading. In contrast, friction in the tensile regime is also affected by the elongation of the junctions. The single SiOx-asperity follows a stick-slip motion on PDMS in both normal force regimes. Statistical analysis of stick-slip as a function of the normal force allows determining the necessary amount of energy to break a SiOx/PDMS junction. Friction between a SiOx-asperity and a PDMS surface can be rationalized based on an energy criterion for the deformation and slippage of nanometer-scale junctions.
Cognitive and Psychological Impacts of Congenital Corpus Callosum Disorders in Adults: A Scoping Review
Authors: Maxfield Maree , McVilly Keith , Devine Alexandra , Jordan Helen
Published: March 2023

Objectives

Support for adults with congenital corpus callosum disorders (CCDs) is impeded by poor understanding of the impacts of a CCD on day-to-day functioning and quality of life. This scoping review examines existing literature to establish the evidence-based impacts of congenital CCDs in adults and identify gaps to inform future research, policy development, and service delivery.

Methods

We conducted searches in Scopus, Medline Ovid, PsycInfo, Discovery, and ERIC. Studies meeting selection criteria were peer-reviewed, in English, published from 1980 to 2021, reported predominantly on participants 16 years or older who were diagnosed with a CCD by magnetic resonance imaging (MRI).

Results

The thirty-eight included articles comprised 14 single/dual participant case studies and 24 group studies, comparing adults with a CCD with normative data or matched controls. Although most participants were of average IQ, CCDs affected day-to-day executive functioning, social interaction, and meeting expectations of adulthood. Cognitive impacts included difficulties with learning and memory, linguistic and emotional processing, and complex reasoning, with functional capacity typically decreasing as tasks and situations increased in complexity. Psychological impacts pertaining to feelings, emotions, and social awareness were reported in addition to associated mental health, psychiatric mood, and developmental and psychotic disorders including autism, anxiety, depression, and schizophrenia.

Conclusions

Impacts were extremely heterogenous, presenting interwoven challenges to learning, executive functioning, social interaction, and mental health. Knowledge of these circumstances is vital for adults with CCDs, professionals, and family members to ensure appropriate services and support are available to promote good quality, inclusive lives for all adults with a CCD.
Albert algebras over and other rings
Authors: Garibaldi Skip , Petersson Holger P. , Racine Michel L.
Published: March 2023

Albert algebras, a specific kind of Jordan algebra, are naturally distinguished objects among commutative nonassociative algebras and also arise naturally in the context of simple affine group schemes of type$\mathsf {F}_4$,$\mathsf {E}_6$, or$\mathsf {E}_7$. We study these objects over an arbitrary base ringR, with particular attention to the case$R = \mathbb {Z}$. We prove in this generality results previously in the literature in the special case whereRis a field of characteristic different from 2 and 3.
Infection prevention and antibiotic stewardship program needs and practices in 2021: A survey of the Society for Healthcare Epidemiology of America Research Network
Authors: Coffey KC , Keller Sara C. , Anderson Deverick J. , Deloney Valerie M. , Harris Anthony D. , Henderson David , Milstone Aaron M. , Morgan Daniel J. , Rock Clare , Schweizer Marin , Chiotos Kathleen
Published: March 2023

In total, 50 healthcare facilities completed a survey in 2021 to characterize changes in infection prevention and control and antibiotic stewardship practices. Notable findings include sustained surveillance for multidrug-resistant organisms but decreased use of human resource-intensive interventions compared to previous surveys in 2013 and 2018 conducted prior to the COVID-19 pandemic.
Observing tidal effects on the dynamics of the Ekström Ice Shelf with focus on quarterdiurnal and terdiurnal periods
Authors: Fromm Tanja , Schlindwein Vera , Helm Veit , Fofonova Vera
Published: March 2023

Antarctica's ice shelves stabilize the ice sheet and, therefore, understanding processes affecting the mass budgets of ice shelves is important for estimating grounded ice loss. To study the ice shelf dynamics, we analyzed seismological and GNSS data from the Ekström Ice Shelf in Dronning Maud Land. We extracted probabilistic power spectral densities (PPSD) in the frequency band 3.4–6.8 Hz, typical of icequakes, from seismological data and observed pronounced signals in the PPSD with near 3 and 4 cycles per day (cpd) corresponding to tidal overharmonics, in addition to the main tidal constituents near 1 and 2 cpd. GNSS data reveal the same components in ice flow speed but not in vertical displacements. Generally, tide-induced grounding line migration modulates the flow velocity of an entire ice shelf. We find that this velocity modulation causes the increased icequake activity in the tidal overharmonics with 3 and 4 cpd in an ice shear zone where the flow velocity drops to nearly zero.
Numerical solutions of the Euler equations governing axisymmetric and three-dimensional transonic flow
Authors: Causon D. M. , Ford P. J.
Published: March 2023

A computational method is presented for solving numerically the three dimensional Euler equations for transonic flow around practical aircraft forebodies. The Euler solver is pseudo-time dependent, split and cast in finite volume form. Shock waves are captured crisply without the need for additional smoothing by means of an operator-switching facility which more accurately reflects the direction of propagation of signals.

The method is illustrated by examples of computed external, axisymmetric flows and some, simulated, realistic aircraft fore-bodies. The computational meshes employed in the three dimensional cases are essentially of cylindrical polar, flow conforming, type and relatively coarse. Closer attention to the mesh generation is expected to refine the results presented here. The method is versatile, robust, and holds promise for treating complex three dimensional geometries within economically viable run times.
Effects of mixed elastic rotational edge restraints on the vibration, buckling and bending of circular plates
Authors: Gunaratnam David J. , Bhattacharya A. P.
Published: March 2023

A general formulation based on a variational approach is used to study the static bending, vibration and stability of circular plates having mixed elastic rotational constraints at the boundary. A single displacement function suitable for these three classes of problems is used in a Ritz scheme to obtain static bending solutions and eigenvalues for various combinations of boundary parameters that exhibit symmetry about two axes. Results obtained are generally in good agreement with those available in the literature and in some cases represent an improvement on those previously reported. The lowest eigenvalues for the stability problem are presented for the first time.
Hardware integrity
Authors: Cullyer W. J.
Published: March 2023

Research at RSRE has revealed significant problems in the use of commercial microprocessors in safety critical equipment. The difficulties arise from the imprecise documentation of the instruction sets by the microprocessor manufacturers and changes in internal design and external functionality during the years a popular device is marketed. To meet certain defence needs, RSRE is conducting research on formal methods of design and implementation of VLSI chips which provide simple processing capability and can be proved to be functionally correct. The first product of this research is a new 32-bit microprocessor architecture, called VIPER, which is described in outline in this paper. Although the primary application of such high integrity devices is in the defence field it is believed that they would be of great value in civil aviation, both in fast control loops in aircraft and in the control of critical DVOR/ DME, ILS and MLS transmitters on the ground.
Aerodynamics — the role of the computer
Authors: Hancock G.J.
Published: March 2023

Tonight, once again, we honour the memory of Frederick William Lanchester, one of the great pioneers of modern engineering, born in 1868 died in 1946. We keep his memory alive by exploring how his ideas and concepts have flowered into maturity, and by reminding ourselves that his example, philosophy and strength of purpose are still relevant in today’s world. I suppose each of us reacts individually to the life and work of a great man.
Static and dynamic pitch stability of a blunted cone with forward facing aerodynamic spike in hypersonic flow
Authors: Hutt G.R. , East R.A.
Published: March 2023

This paper presents experimental data highlighting the effects of a forward facing aerodynamic spike on the pitch stability of a blunted cone in hypersonic flow. Spike length and angle of attack variations on stability derivatives are described. Suitable application of the inviscid embedded Newtonian pitch stability prediction technique shows how the influence of spike aerodynamics may be successfully modelled. The paper extends the knowledge of aerodynamic spike flow effects, which have to date concentrated on aerodynamic drag reduction qualities at zero degrees angle of attack.
On the effects of boundary-layer transition on a cylindrical afterbody at incidence in low-speed flow
Authors: Poll D. I. A.
Published: March 2023

The experimentally observed changes in the location of boundary layer separation on the cylindrical afterbody of a tangent-ogive-cylinder, placed at incidence in a uniform flow, are related to the phenomenon of laminar-turbulent transition. Existing knowledge of the transition mechanisms which operate in general, three-dimensional; boundary layers, is described and simple prediction criteria are derived for this configuration. These criteria are compared with the currently available empirical methods for the prediction of critical Reynolds numbers for such flows. It is demonstrated that the methods which have been published to date are incomplete and the accompanying analyses are based upon superficial and erroneous physical arguments. The implications of boundary layer transition on the normal forces generated by a cylindrical afterbody are also discussed. Finally, the possibility of using transition fixing to establish ‘high Reynolds number’ separated flows in ‘low Reynolds number’ wind-tunnel facilities is briefly considered.
Frequency-domain application of Gauss-Newton method to extract aircraft longitudinal parameters
Authors: Raisinghani S. C. , Goelt A. K.
Published: March 2023

A simplified output error method based on the Gauss-Newton minimisation technique is formulated in the frequency-domain and its application demonstrated for extraction of aircraft longitudinal parameters from simulated flight data. A study is carried out to show the effects on the accuracy of estimated parameters due to use of different input forms to generate the flight data, using different initial values to start the algorithm, presence of measurment noise in the flight data and fixing some weak parameters at a priori values. It is shown that the use of Packing Theorem to increase the sparsely sampled frequency data does not lead to better accuracy by the proposed method, as has been reported for the maximum likelihood method in the literature. Finally, relative advantages of the frequency-domain approach as against the time-domain approach are pointed out by analysing the same flight data in these two domains. It is shown that frequency-domain approach is better equipped to analyse noisy-data and can yield better estimates at reduced computational time.
The assessment of boundary layer two-dimensionality
Authors: Fraser C. J.
Published: March 2023

The results of an experimental evaluation of three assessment criteria for boundary layer two-dimensionality are presented. The criteria include the so-called ‘two pin test', the momentum balance principle and the cross-stream variation in local skin friction coefficient. Extensive spanwise measurements in the flows investigated highlight the relative merits and limitations of the criteria imposed.

The momentum balance method is found to be the most informative technique, with the proviso that the test data must be interpreted with some care if measurements are restricted along a single streamwise axis.

The two pin test is found to provide a worthwhile complimentary addition to momentum balance data, whereas the spanwise variation in local skin friction coefficient is less conclusive as regards flow two-dimensionality.

Excepting the case of adverse pressure gradient flows, the momentum balance equation is seen as a viable experimental means of estimating the local skin friction coefficient in boundary layers where measurement is problematical, as in the case of transitional boundary layers. In such cases, the two pin test could be used as the sole means of confirming the flow two-dimensionality.
A conic-cubic method for curve fitting and function interpolation
Authors: Skrobański J. J. , Lovell D. A.
Published: March 2023

This paper describes a simple method for smooth curve fitting or function interpolation. Where possible, the method uses continuous piece-wise conies in preference to cubics so as to prevent the occurrence of extraneous inflection points. The method is ideal for single-valued functions with sharply changing gradients such as occur in pressure distributions, containing shock waves. A version that is valid for multivalued functions is also described.
The lateral dynamic stability and control of a large receiver aircraft during air-to-air refuelling
Authors: Bloy A. W. , Lamont P. J. , Abu-Assaf H. A. , Ali K. A. M.
Published: March 2023

The lateral dynamic stability and control of a large receiver aircraft was considered during air-to-air refuelling. A simple aerodynamic model was developed in order to determine the aerodynamic forces and moments acting on the receiver aircraft due to the tanker aircraft's vortex field. These forces and moments were then expressed in derivative form and included in the linearised equations of motion. Solution of these equations revealed a divergent oscillation, characteristic of air-to-air refuelling and consisting mainly of bank and sideways displacements. An approximation to this mode, which highlights two important aerodynamic derivatives was made. The values of these derivatives depend mainly on the vertical separation between the tanker and receiver aircraft and the ratio of the tanker-to-receiver aircraft wing spans. In flight, it appears that the pilot controls the divergent mode by frequent alternate movements of the ailerons.
Pressure fluctuations caused by transonic
shock/boundary-layer interaction
Authors: Mundell A. R. G. , Mabey D. G.
Published: March 2023

An analysis of an extensive series of unsteady and steady pressure measurements at transonic speeds on a rigid 12% thick NACA 16 series aerofoil reveals a useful classification of the type of excitation characteristics of particular flow regions.

The pressure fluctuation measurements suggest that when the shock from the aerofoil reaches the tunnel roof, serious interference (both dynamic and static) occurs.

The RAE 2 ft × 1½ ft Transonic Tunnel used for the tests has low levels of flow unsteadiness at low frequencies, making it a useful facility for basic research in time-dependent aerodynamics.
What are we in business for? (An engineering approach to project finance)
Authors: Young Pierre
Published: March 2023

It is shown, fairly rigorously, that large aerospace projects, with typical periods of 15 years to break even, are unlikely to provide a commercial rate of return on a ‘risk’ investment. However, they can generate enough surplus to meet an alternative criterion, the ‘self-financing ratio’, which emphasises the contribution made by the Project to the future self-financing capability of the company. Until this blessed state is achieved, the industry needs ‘cheap money’ whose main source can only be the taxpayer. The role of the taxpayer as investor is examined with the help of an elementary econometric model. A form of ‘Prospectus to the Taxpayer’ is developed which summarises the quantifiable benefits to the national economy arising from the launch of a project. The same methods are also applied to the formulation of a ‘Home-Purchase Discount’, intended as an aid to government procurement decisions. The concluding remarks emphasise that the paper is relevant primarily to the ‘large scale high R&D sector’ of industry, of which aerospace is a prominent component.

Finally, the views expressed in this paper are my own and emphatically do not reflect those of the Company I have the honour to serve in other fields
Two-dimensional flow past bluff flexible membranes of low porosity
Authors: Low H. T. , Newman B. G.
Published: March 2023

This paper considers two-dimensional flow past flexible membranes whose supports are aligned at right angles to the flow. Unlike a previous study of bluff impervious membranes, the present membranes are slightly porous having a porosity similar to that of parachutes. The drag and base pressure have been measured for various lengths and for a variety of fabrics. The results have been correlated by two theories which are extensions of those already published. When the porosity is not too small the results are shown to depend only on the total volume flow through the membrane. The tendency for the membrane to oscillate in harmony with regular vortex shedding is reduced by the porosity and increased by the length of the membrane. Above a certain porosity oscillation is inhibited for all membrane lengths.
Some examples of the application of the Beecham-Titchener-Simpson (BTS) method to autonomous systems
Authors: Christopher P. A. T. , Thorne R.
Published: March 2023

It is noted that the averaging technique of Beecham and Titchener, for obtaining approximate solutions to nonlinear, ordinary, differential equations, is not widely known or used. In its extended form, as given by Simpson and Ross it appears to offer a unified and useful approach to the solution of many dynamical and other problems. The present paper sets out to describe and discuss, through the medium of a collection of examples, the Beecham-Titchener-Simpson (BTS) method in an effort to encourage its more widespread use.
BLOOD ON HIS WORDS, BARLEY ON HIS MIND. TRUE NAMES IN CAESAR'S SPEECH FOR THE LEGENDARY ‘BARLEY-MUNCHER’ (BGALL.7.77)
Authors: Krebs Christopher B.
Published: March 2023

Critognatus’ speech has long been recognized as heavily by Caesar's hand, although few have questioned whether any speech was delivered by the Arvernian noble at all; and it has long puzzled readers with its contradictory manner and fierce criticism of Rome. But the etymologizing wordplay across several languages demonstrated below (along with other distinctly comical elements) renders it more than likely that both the speech and the speaker are products of the author's imagination. In its Nabokovian mode, it offers a glimpse of Caesar the linguist and introduces a playfulness into the dire situation before Alesia that suggests that the ‘Barley-Muncher’ and his speech should be reconsidered in a different, more humorous light.
Stochastic linearized generalized alternating direction method of multipliers: Expected convergence rates and large deviation properties
Authors: Hu Jia , Guo Tiande , Han Congying
Published: March 2023

Alternating direction method of multipliers (ADMM) receives much attention in the field of optimization and computer science, etc. The generalized ADMM (G-ADMM) proposed by Eckstein and Bertsekas incorporates an acceleration factor and is more efficient than the original ADMM. However, G-ADMM is not applicable in some models where the objective function value (or its gradient) is computationally costly or even impossible to compute. In this paper, we consider the two-block separable convex optimization problem with linear constraints, where only noisy estimations of the gradient of the objective function are accessible. Under this setting, we propose a stochastic linearized generalized ADMM (called SLG-ADMM) where two subproblems are approximated by some linearization strategies. And in theory, we analyze the expected convergence rates and large deviation properties of SLG-ADMM. In particular, we show that the worst-case expected convergence rates of SLG-ADMM are
$\mathcal{O}\left( {{N}^{-1/2}}\right)$
and
$\mathcal{O}\left({\ln N} \cdot {N}^{-1}\right)$
for solving general convex and strongly convex problems, respectively, where N is the iteration number, similarly hereinafter, and with high probability, SLG-ADMM has
$\mathcal{O}\left ( \ln N \cdot N^{-1/2} \right ) $
and
$\mathcal{O}\left ( \left ( \ln N \right )^{2} \cdot N^{-1} \right ) $
constraint violation bounds and objective error bounds for general convex and strongly convex problems, respectively.
Design of low-profile high-gain wideband circularly polarized low RCS single-layer metasurface antenna using characteristics mode analysis
Authors: Rana Sourabh , Jain Priyanka
Published: March 2023

In this paper, a novel circularly polarized (CP) high-gain low-profile single-layer metasurface (MTS) antenna fed by a coplanar waveguide is presented for wideband low radar cross-section (RCS) applications. Characteristics mode analysis (CMA) technique is employed to simultaneously excite the useful modes rather than using conventional technique to achieve circular polarization in the wideband. By analyzing the characteristics modes of the antenna, gain of the antenna is also improved. Experimental results verify good performance of the proposed antenna with a compact size of 0.67λ0 × 0.67λ0 × 0.040λ0. The measured results of the antenna exhibit UWB impedance bandwidth of 96.93% in the frequency range of 3.7–10.65 GHz and 3 dB axial ratio bandwidth of about 41.8% in the frequency range of 5.3–8.1 GHz. The antenna shows a good radiation pattern with a measured peak gain of 7.9 dBic at 7.97 GHz. The proposed antenna achieves out-of-band scattering suppression in the wide range of 10–24 GHz because of MTS structure with peak RCS reduction of 19 dB at 12 GHz. The proposed antenna can be used for c- and x-band applications.
Activation of Existing Surface Crevasses Has Limited Impact on Grounding Line Flux of Antarctic Ice Streams
Authors: Gerli C. , Rosier S. , Gudmundsson G. H.
Published: March 2023

Recent studies have identified widespread vulnerable ice shelf regions in Antarctica which are both highly buttressed and susceptible to crevasse hydrofracturing, raising concern for potential crevasse driven ice‐shelf collapse and future sea level rise. Here, we employ the finite element ice flow model, Úa, to investigate whether crevasses which have propagated through the entire ice column have a significant impact on upstream flow and quantify their contribution to sea level rise. We find a large variability in the response of ice shelves to this perturbation, with changes in grounding line flux as large as 155% for the Filchner‐Ronne and 46% for the Ross, when compared to the present day. Crevasses located close to the grounding lines contribute most of this change. When compared to a second perturbation in which ice shelves are completely removed, however, the response is relatively small for all modeled ice shelves.
Role of Tropical Cyclones in Determining ENSO Characteristics
Authors: Li Hui , Hu Aixue , Meehl Gerald A.
Published: March 2023

El Niño‐Southern Oscillation (ENSO) can effectively modulate global tropical cyclone (TC) activity, but the role TCs may play in determining ENSO characteristics remains unclear. Here we investigate the impact of TC winds on ENSO using a suite of Earth system model experiments where we insert TC winds, extracted from a TC‐permitting high‐resolution simulation, into a low‐resolution model configuration with nearly no intrinsic TCs. The presence of TC winds in the model increases ENSO power and shifts ENSO frequency closer to what we observe. TCs lead to an increase of strong to extreme El Niño events seen in observations and not simulated in the low‐resolution model without intrinsic TCs, mainly through enhanced zonal advection feedback and thermocline feedback. Our results indicate that TCs play a fundamental role in producing the ENSO characteristics we experience today in the climate system and point to a two‐way climatological interaction between TCs and ENSO.
Alteration of Magnetic Field Strength in the Strong Crustal Field Region at Mars by Currents Induced by the Solar Wind Interaction
Authors: Renzaglia A. , Cravens T. E. , Hamil O.
Published: March 2023

Crustal magnetic fields on Mars were first found by the Mars Global Surveyor and reported in 1998. One interesting aspect of the interaction between crustal fields and the Martian ionosphere is the impact on total ion loss over time, which is a central question addressed by the Mars Atmospheric and Volatile EvolutioN (MAVEN) spacecraft currently orbiting Mars. In this work, we seek to improve understanding of the impact of crustal fields on plasma energetics, and consequent ion loss, by examining the effects of ionospheric current sheets that may form at the boundary between crustal and induced magnetic fields. These current sheets will not just affect the external induced field regions but will also affect the observed magnetic fields in the crustal field regions. Variations in field strength should be evident by comparing crustal field models and measured magnetic fields collected by the MAVEN magnetometer instrument (MAG). One way to confirm such variation is to compare dayside and nightside orbit pairs that occur over the same crustal field regions. The induced magnetic field exists mostly on the dayside and is largely absent on the nightside. We examine these orbit pairs and discuss the perturbation of magnetic fields in the dayside ionosphere. We confirm that deviations on the dayside are larger than on the nightside, and that current sheets in the ionosphere could be responsible for these deviations, particularly in the strong crustal field regions.