bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasonic NDE of Transverse Cracks in Laminated Composites
Authors: Maslov K. , Kim R. , Kinra V. K. , Pagano N.
Published: January 2022

Detection of transverse cracks in laminated composites is important for the development and verification of damage-growth models. Historically, it has been assumed that the matrix cracks propagate all the way across the width of a test coupon. When this happens, the dye-penetrant technique works well for the detection of cracks. However, when a crack starts at one edge but does not run all the way across (a partial crack) or when the crack is totally internal, the dye-penetrant method does not give satisfactory results. Moreover, the dye-penetrant technique cannot be used for in-situ testing. The objective of this paper is to report the development of an ultrasonic method for in-situ detection of partial or internal across-the-width cracks.

In the transmission mode, a pair of 20-MHz focused transducers was used in the pitch-catch arrangement. The angle of incidence was chosen to exceed the critical angle for the excitation of a longitudinal wave. This results in the excitation of a shear wave which is more sensitive for the detection of transverse cracks.

Sometimes access is limited to only one side of the plate. To cover these situations, a reflection technique was also developed. Here, higher-order Lamb-wave modes were used (Modes 1 and 3; frequency range 4 MHz – 11 MHz). The advantage here is that in the absence of a crack, there is no reflection, i.e., the wave “sees” a crack against a “dark background”. Moreover, the inspection can be done at a lower frequency where wave propagation is less sensitive to plate surface roughness. A disadvantage is that the spatial resolution of the reflection mode is not as good as that of the transmission mode.

The technique was used to examine a number of graphite/epoxy [0,90,0] coupons, 0.5mm–1mm thick, which had been subjected to monotonic tensile loading prior to the ultrasonic test. A large number of transverse cracks were detected. As expected, a majority of the cracks ran all the way across the width of the test coupon. Some of the cracks started at one edge but were arrested in the middle. Occasionally a crack that started and stopped in the interior was detected. The cracks were also recorded by an examination of the edges using an optical microscope; an excellent correlation between the optical and the ultrasonic images was observed.

It is well known that a closed crack cannot be detected by the use of ultrasound. It is considered possible that what is ultrasonically perceived as a partial crack may, in fact, be an across-the-width crack with a part of its length closed (due, for example, to residual stresses). In order to guard against this possibility the following experiments were conducted. A plate was subjected to a significant bending moment, guaranteeing that at least one half of the crack (the half that occupies the tensile half of the plate) is open. No difference in the ultrasonic images with or without bending was observed. It is concluded that the technique is suitable for the detection of partial and internal cracks.
Rayleigh Waves Propagating Along an Oblique Cut Surface of Directional Fiber Reinforced Composites
Authors: Ohyoshi Tadashi
Published: January 2022

It is well known that the major contribution to an impact response of solid material is the surface waves propagating along a free edges of the plate materials. Then, the subject is focused to the characteristic waves relating to a fiber reinforced composite material. The stress free surface is the cross section generated in mechanical production process by cutting at off-angle to a material symmetric axis. The analytical results show that the cutting angle and fiber volume fraction of composite materials affect the path and direction of particle motion considerably as well as the phase velocity. In the analysis, classical effective modulus theory was used because the wave length is quite large comparing with the geometrical dimensions of composites in most practical cases. The elastic constants are set under the plane stress condition. Numerical calculation was carried out for a glass fiber reinforced epoxy resin matrix composite; Young’s modulus Ef = 73.1[GPa], Em = 3.45[GPa], Poisson ratio vf = 0.22, vm = 0.35, density Df = 2.6[g/m3], Dm = 1.15[g/m3], and miss-alignment factor k = 0.95. The graphs have been made by selecting the parameters of off-angle and volume fraction of fiber. The numerical results show us the some interesting phenomena. For example, the characteristic Rayleigh waves studied are the different ones from the conventional ones. The Rayleigh wave propagating along the oblique cut surface, is composed of two different body waves, quasi-longitudinal P-wave and quasitransverse S-wave. Furthermore, phase plane directions of the body waves are different each other, and they are not orthogonal to the free surface any more. These characteristic results provide important information for analyses of dynamic response of a fiber reinforced composite material.
Electrical Resistance Measurements in Carbon-Carbon Composites
Authors: Ochoa O. O. , Parker P. A.
Published: January 2022

In-situ electrical resistance measurements of carbon-carbon laminates were obtained in an oxidizing environment at 900 C. Scanning electron and optical microscopy were utilized to interpret the physical damage incurred from oxidation and its impact on the mechanical and electrical properties of the carbon-carbon substrate. The interpretation of the relationships between the percent mass loss, shear modulus, and electrical resistance provided an excellent venue to design future tests. Rescor 780 alumina oxide castable ceramic test fixture used for the electrical resistance measurement was designed and fabricated in our lab.

Microscopy observations of specimens exposed for forty minutes revealed preferential fiber loss in both longitudinal and transverse directions. Rheometry tests revealed that the in-plane shear modulus degraded with increasing oxidation time and mass loss. On the other hand the electrical resistance increased with increasing oxidation time and mass loss. The electrical resistance change is controlled primarily by the bulk electrical resistivity, which is a matrix controlled characteristic. As oxidation time increased, the electrical properties of the specimen approached those of the matrix.

The carbon-carbon specimens used had four constituents; Silicon carbide (SiC) coating at the top and bottom surfaces of the substrate composed of T-300 carbon fibers, carbon matrix, and the oxidation inhibitor boron carbide (B4C) which chemically react with oxygen and become boric oxide (B2O3). Each of these four components contributes to the oxidation characterization of the specimen and can be represented by a simple, parallel electrical resistance model. Consequently, for a given value of either the shear modulus, electrical resistance, or mass loss the other two values can be easily obtained. The results show that the analytical simulation is on average within 4.7% of the averaged experimental value. Correlation between the shear modulus and the electrical resistance is illustrated in Figure 1.
Inelastic Response of Porous, Hybrid Fiber Composites
Authors: Roerden Alysha M. , Herakovich Carl T.
Published: January 2022

A methodology is presented for a micromechanics model of the inelastic response of porous, hybrid fiber composites. The composite, designated A-PA/IC50, consists of porous hybrid fibers (Nextel 610 alumina filaments in a porous alumina binder) in a nickel alloy matrix (IC50 nickel aluminide). Using Aboudi’s Generalized Method of Cells (GMC), the elastic and inelastic response of the composite is modeled in a three step process. The first step uses the 3-D version of GMC to predict the elastic properties of the porous alumina binder as a function of the percent porosity. These properties of the porous binder are then used in a 2-D analysis of the hybrid with the filaments taken to be linear elastic. Properties of the hybrid fiber are thus available as a function of the present porosity as well as the percent of filaments in the hybrid fiber. Finally, the elastic properties and inelastic response of the composite are predicted using 2-D GMC with the hybrid fiber taken to be elastic and the nickel matrix inelastic. The inelastic matrix is modeled using the Bodner-Portom unified visco-plasticity theory. Input properties of the constituents were determined from laboratory measurements. Representative predictions showing the influence of percent porosity (of the alumina binder in the hybrid fiber) and percent hybrid fiber in the composite on the axial and transverse responses of the composite are shown in the figures below.

Clearly, both the porosity and the percent hybrid fiber have an influence on the elastic modulus, the proportional limit, and inelastic response. Details of the methodology and additional results for axial, transverse and shear properties will be presented in the full paper.
Static and High Strain Rate Compression Testing of Thick Section S-2 Glass/Vinyl Ester Composites for Integral Armor Application
Authors: Hosur M. V. , Vaidya U. K. , Jadhav N. , Jeelani S.
Published: January 2022

Integral armor concepts are of primary interest to armored vehicles requiring ballistic protection. A composite integral armor provides multi-interface, multi-functional capability, easy reparability, quick deployment, enhanced ballistic performance and lightweight advantages. The typical design of integral armor is seen to utilize a combination of thick section S2-glass vinyl ester structural composite, alumina, ceramic tiles, resilient rubber, fire retardant, phenolic layer and several signature/functional layers. Thick composite laminate serves as the primary load-bearing component of the integral armor used in the upper hull of a Composite Armored Vehicle (CAV). Current solution of the structural laminate (typically 0.8” thick) comprises an S2-glass/epoxy automated fiber placed laminate. Currently used processing techniques such as automated fiber placement prove to be costly and time consuming.

In the current study, several alternative cost-effective processing solutions are employed. They include Vacuum Assisted Resin Transfer Molding (VARTM) and Vacuum Assisted Resin Infusion Molding (VARI) and their variations. Both VARTM and VARI use low viscosity resins, however, the consolidation conditions that the laminate undergoes are significantly different Composite laminates are made using 45 layer of 2 × 2 twill weave S2-glass with 933 sizing /vinyl ester C-50 resin. Effectiveness of the different fabrication methods is compared in terms of the compression behavior of the laminates. Both static as well as high strain rate test using Split Hopkinson’s bar technique are studied.
Spin- and time-resolved photoelectron spectroscopy and diffraction studies using time-of-flight momentum microscopes
Authors: Schönhense Gerd , Elmers Hans-Joachim
Published: January 2022

Momentum microscopy (MM) is a novel way of performing angle-resolved photoelectron spectroscopy (ARPES). Combined with time-of-flight (ToF) energy recording, its high degree of parallelization is advantageous for photon-hungry experiments like ARPES at x-ray energies, spin-resolved and time-resolved ARPES. This article introduces the technique of ToF-MM and illustrates its performance by selected examples obtained in different spectral ranges. In a multidimensional view of the photoemission process, spectral density function ρ(k,EB), spin polarization P(k,EB), and related quantities of circular dichroism in the angular distribution (CDAD) are part of the “complete experiment,” a concept adopted from atomic photoemission. We show examples of spin-resolved valence-band mapping in the UV and VUV, and the soft- and hard-x-ray range. Spin mapping of the Heusler compounds such as Co2MnGa and Co2Fe0.4Mn0.6Si at hν = 6 eV proves that the second compound is a half-metallic ferromagnet. Analysis of the Tamm state on Re(0001) using VUV-excitation reveals a Rashba-type spin texture. Bulk band structure including Fermi surface, Fermi-velocity distribution vF(k,EF), full CDAD texture, and spin signature of W(110) have been derived via tomographic mapping with soft x-rays. Hard x rays enable accessing large k||-regions so that the final-state sphere crosses many Brillouin zones in k-space with different kz’s. At hν = 5.3 keV, this fast 4D mapping mode (at a fixed hν) revealed the temperature dependence of the Fermi surface of the Kondo system YbRh2Si2. Probing the true bulk spin polarization of Fe3O4 at hν = 5 keV proved its half-metallic nature. The emerging method of ToF-MM with fs x-ray pulses from free-electron lasers enables simultaneous valence, core-level, and photoelectron diffraction measurements in the ultrafast regime.
Sign and Sense of an Induced Electric Current by a Nearby Moving Magnet
Authors: Rojas Roberto
Published: January 2022

In one of the Faraday’s experiments an electric current is induced in a conducting loop when a magnet in front of it moves towards or away from the loop. While the direction of circulation of the electric current in the loop has only two options, it depends on three experimental conditions that generate eight cases. Even though the Faraday law or the Lenz law by itself answers for the current sense in each case, we think that a graphic synthesis of all the cases and its corresponding result is a new and interesting exercise we want to discuss. The resulting diagram is a starting point for other exercises on the induced current that a teacher might propose to their students in introductory college physics.
Dynamics Experiments on the Touch Panel of a Tablet Computer
Authors: Aok Yuki , Yawata Kazushi
Published: January 2022

A new system for tracking a metal ball rolling on the slope of the touch panel of a tablet computer was developed. The widespread introduction of tablets in educational environments allows the use of a convenient dynamic measurement in schools.
Reflecting on a difficult year
Authors: Iyer Deepak , Wachowski Shannon
Published: January 2022

For this month’s article, we reflect on the impact of COVID and existing challenges in education that have become exacerbated over the past two years. We bring our own perspectives and experiences, and those from the broader communities we belong to. We hope that they will resonate with your thoughts, feelings, and experiences too.
Making the Quantum Scattering of Fundamental Particles Accessible
Authors: Day James , Liao Theresa Yu-Huan , Hoyt Char , Can Oguzhan
Published: January 2022

This paper shares a hands-on activity that introduces Feynman diagrams and the accompanying idea of using pictorial representations to describe the behavior of subatomic particles—specifically, for electrons and photons—in place of mathematical expressions. Built collaboratively by scientists and artists, it exemplifies a triumph of lateral thinking by highlighting the vital role Feynman diagrams have played in modern physics. While the student may initially treat this activity as a glimpse into the quantum realm, the teacher should recognize this as a demonstration of lateral thinking as an insight tool.
When the Quarter Jumps into a Cup (and When It Does Not)
Authors: Dutra Mateo , Suárez Álvaro , Monteiro Martín , Martí Arturo Carlos
Published: January 2022

While Bernoulli’s equation is one of the most frequently mentioned topics in physics literature and other means of dissemination, it is also one of the least understood. Oddly enough, in the wonderful book Turning the World Inside Out, Robert Ehrlich proposes a demonstration that consists of blowing a quarter coin into a cup, incorrectly explained using Bernoulli’s equation. In the present work, we have adapted the demonstration to show situations in which the coin jumps into the cup and others in which it does not, proving that the explanation presented in Ehrlich’s book based on Bernoulli’s equation is flawed. Our demonstration is useful to tackle the common misconception, stemming from the incorrect use of this equation, that higher velocity invariably means lower pressure.
Effectiveness of the Type of Feedback on Learning to Pass in Volleyball
Authors: López-Ferrer Adrià , Marco-Ahulló Adrià , Monfort-Torres Gonzalo , Ramón-Llin Jesús , de Moraes Filho, Joao Alves , García-Massó Xavier
Published: January 2022

Objective: To determine which type of feedback (visual, verbal, or both combined) facilitates to a greater extent the learning of a specific skill (passing in volleyball). Methods: Three groups of students between 14 and 15 years of age belonging to the third year of Compulsory Secondary Education in a Spanish public high school (n = 58) were randomly assigned a type of feedback implemented in the part of the syllabus dedicated to volleyball. The students’ knowledge, motor performance, accuracy, and self-perception about the action were evaluated before and after the intervention and enjoyment afterwards. Results: All the groups obtained improvements in all the variables studied (p < .05); the verbal and visual feedback group was the one that obtained greater improvements, showing also a greater enjoyment than the visual feedback group. Conclusions: It has been found that the use of the combination of verbal and visual feedback is most recommended for learning a specific skill, such as passing in volleyball.
Genetic Analysis Using Vitamin B
6
Antagonist 4-Deoxypyridoxine Uncovers a Connection between Pyridoxal 5′-Phosphate and Coenzyme A Metabolism in Salmonella enterica
Authors: Vu Huong N. , Downs Diana M.
Published: January 2022

PLP is a ubiquitous cofactor required by enzymes in diverse metabolic networks. The data presented here expand our understanding of the toxic effects of dPN, a vitamin B
6
antagonist that is often used to mimic vitamin B
6
deficiency and to study PLP-dependent enzyme kinetics.
The Diverse World of Protists—an Ideal Community with which to Introduce Microscopy in the Microbiology Teaching Laboratory
Authors: Van Etten Julia , Keddis Ramaydalis , Lisa Jessica , Rauschenbach Ines
Published: January 2022

Protists and other eukaryotes are present in diverse terrestrial and aquatic environments. They can easily be collected from local ponds and streams.
Fifteen-minute consultation: Is this umbilical venous catheter safe to use?
Authors: Manea Cristina , Pryce Russell , Ramadan Ghada
Published: January 2022

Umbilical venous catheters are widely used in neonatal practice, therefore promoting safe use of such catheters to reduce complications remains a healthcare priority. This report will equip the reader with essential knowledge for successful catheter insertion and maintenance, which is key to better outcomes. Recent advances in safe localisation of catheter tip and the development of a red flag system will enhance the clinician’s ability to predict potential complications related to these catheters as they remain in situ.
Lung volume distribution in preterm infants on non-invasive high-frequency ventilation
Authors: Gaertner Vincent D , Waldmann Andreas D , Davis Peter G , Bassler Dirk , Springer Laila , Thomson Jessica , Tingay David Gerald , Rüegger Christoph Martin
Published: January 2022

Introduction

Non-invasive high-frequency oscillatory ventilation (nHFOV) is an extension of nasal continuous positive airway pressure (nCPAP) support in neonates. We aimed to compare global and regional distribution of lung volumes during nHFOV versus nCPAP.

Methods

In 30 preterm infants enrolled in a randomised crossover trial comparing nHFOV with nCPAP, electrical impedance tomography data were recorded in prone position. For each mode of respiratory support, four episodes of artefact-free tidal ventilation, each comprising 30 consecutive breaths, were extracted. Tidal volumes (VT) in 36 horizontal slices, indicators of ventilation homogeneity and end-expiratory lung impedance (EELI) for the whole lung and for four horizontal regions of interest (non-gravity-dependent to gravity-dependent; EELINGD, EELImidNGD, EELImidGD, EELIGD) were compared between nHFOV and nCPAP. Aeration homogeneity ratio (AHR) was determined by dividing aeration in non-gravity-dependent parts of the lung through gravity-dependent regions.

Main results

Overall, 228 recordings were analysed. Relative VTwas greater in all but the six most gravity-dependent lung slices during nCPAP (all p<0.05). Indicators of ventilation homogeneity were similar between nHFOV and nCPAP (all p>0.05). Aeration was increased during nHFOV (mean difference (95% CI)=0.4 (0.2 to 0.6) arbitrary units per kilogram (AU/kg), p=0.013), mainly due to an increase in non-gravity-dependent regions of the lung (∆EELINGD=6.9 (0.0 to 13.8) AU/kg, p=0.028; ∆EELImidNGD=6.8 (1.2 to 12.4) AU/kg, p=0.009). Aeration was more homogeneous during nHFOV compared with nCPAP (mean difference (95% CI) in AHR=0.01 (0.00 to 0.02), p=0.0014).

Conclusion

Although regional ventilation was similar between nHFOV and nCPAP, end-expiratory lung volume was higher and aeration homogeneity was slightly improved during nHFOV. The aeration difference was greatest in non-gravity dependent regions, possibly due to the oscillatory pressure waveform. The clinical importance of these findings is still unclear.
Recovery from resistance exercise in older adults: a protocol for a scoping review
Authors: Hayes Eleanor Jayne , Stevenson Emma , Sayer Avan Aihie , Granic Antoneta , Hurst Christopher
Published: January 2022

Introduction

Resistance exercise has been shown to improve muscle health in older adults and is recommended as a front-line treatment for many health conditions, including sarcopenia and frailty. However, despite considerable research detailing the potential benefits of resistance exercise programmes, little is known about how older adults recover from individual exercise sessions. This scoping review will examine the current evidence surrounding the acute post-exercise effects of resistance exercise and the exercise recovery process in older adults to inform future research and exercise prescription guidelines for older adults.

Methods and analysis

The methodological framework of Arksey and O’Malley (2005) will be applied for this scoping review. A systematic search of five online databases and the hand-searching of reference lists of identified articles will be used to identify relevant papers. Studies that aim to measure exercise-induced muscle damage or exercise recovery following a resistance exercise session in participants aged 65 years and over will be included. Qualitative and quantitative data from relevant studies will be presented in a tabular format. Results will be summarised in narrative format. Key findings will be discussed concerning resistance exercise prescription in older adults.

Dissemination

This review will be used to direct further research surrounding the exercise recovery process from resistance exercise in older adults and will also aid in designing specific exercise prescription guidelines for an older population. Findings will be relevant to researchers, clinicians, health workers and policy-makers and disseminated through publications and presentations.
Case studies on psychosocial factors that help make exercise programmes for prostate cancer patients self-sustaining
Authors: Fox Isaac Nikolai , Wassersug Richard
Published: January 2022

Objectives

Patients with prostate cancer (PCa) benefit from regular exercise, but it is difficult for patients to maintain an exercise regime. We examined two exercise programmes that have proven to be self-sustaining with the goal of identifying features they share that may contribute to their success.

Methods

We compared the FC Prostata football (soccer) league in Denmark and the ‘Butts in a Boat’ (BIAB) dragon-boating team in Canada. The FC Prostata Project Coordinator and the BIAB team leaders provided information on their programmes’ history and structure.

Results

Both programmes are team-based with regularly scheduled intense exercise at their core. In both cases, social activities evolved spontaneously, starting with the men going out for food and/or drinks after practices. The sustainability of these programmes may be driven by the regular socialisation linked to the fitness activities.

Conclusions

Our case studies suggest that exercise programmes for PCa patients may have a good chance of being self-sustaining, if they are: (1) centred around intense exercise, (2) of a team nature, (3) structured to promote egalitarianism and avoid one-on-one competition within teams, yet (4) have some competitions between teams. The data suggest that informal social activities organised by patients after team practices may be important for building fellowship and strengthening patients’ commitment to exercise both for themselves and for their team members.
Impact of a rapid access chest pain clinic in Singapore to improve evaluation of new-onset chest pain
Authors: Toh Lay Cheng , Khoo Christina , Goh Cheng Huang , Choa Gary , Quek Lit Sin , Phang Jonathan , Wong Franco , Tsou Keith , Kwan Yew Seng , Kojodjojo Pipin
Published: January 2022

Background

Chest pain (CP) accounts for 5% of emergency department (ED) visits, unplanned hospitalisations and costly admissions. Conversely, outpatient evaluation requires multiple hospital visits and longer time to complete testing. Rapid access chest pain clinics (RACPCS) are established in the UK for timely, cost-effective CP assessment. This study aims to evaluate the feasibility, safety, clinical and economic benefits of a nurse-led RACPC in a multiethnic Asian country.

Methods

Consecutive CP patients referred from a polyclinic to the local general hospital were recruited. Referring physicians were left to their discretion to refer patients to the ED, RACPC (launched in April 2019) or outpatients. Patient demographics, diagnostic journey, clinical outcomes, costs, HEART (History, ECG, Age, Risk Factors, Troponin) scores and 1-year overall mortality were recorded.

Results

577 CP patients (median HEAR score of 2.0) were referred; 237 before the launch of RACPC. Post RACPC, fewer patients were referred to the ED (46.5% vs 73.9%, p < 0.01), decreased adjusted bed days for CP, more non-invasive tests (46.8 vs 39.2 per 100 referrals, p = 0.07) and fewer invasive coronary angiograms (5.6 vs 12.2 per 100 referrals, p < 0.01) were performed. Time from referral to diagnosis was shortened by 90%, while requiring 66% less visits (p < 0.01). System cost to evaluate CP was reduced by 20.7% and all RACPC patients were alive at 12 months.

Conclusions

An Asian nurse-led RACPC expedited specialist evaluation of CP with less visits, reduced ED attendances and invasive testing whilst saving costs. Wider implementation across Asia would significantly improve CP evaluation.
Anti-excitotoxicity and neuroprotective action of asiaticoside encapsulated polymeric nanoparticles in pilocarpine rodent seizure model
Authors: Kunjumon Renju , Viswanathan Gayathri , Jayasree Devi Velayudhan , Biju Prabath Gopalakrishnan , Prakash Prabha , Sasidharan Baby Chakrapani Pulikkaparambil , Baby Sabulal
Published: January 2022

Asiaticoside (ASI), an ursane-type triterpenoid saponin, isolated from the memory enhancing herb Centella asiatica, is known for its neuroprotective activities. Here, the anti-excitotoxicity and neuroprotective effects of ASI encapsulated alginate chitosan nanoparticles (ACNPs) were evaluated in pilocarpine (PC) induced seizure in mice model. ACNPs were prepared by ionic gelation-polyelectrolyte complex method and their physicochemical characterization was carried out by TEM, SEM, DLS, XRD, and FTIR. Subsequently, their encapsulation efficiency (EE), in vitro drug release, cell viability, seizure score, DNA fragmentation, and mRNA expression of regulatory stress markers were evaluated. Membrane permeability of ACNPs in the brain, histopathology, and biological TEM and SEM analyses were also carried out. TEM of ACNPs showed spherical morphology with a particle size of 200–400 nm. DLS of ACNPs displayed an average size of 486.2 nm with polydispersity index (PDI) of 0.567 and zeta potential of –14.1 mV. ACNPs achieved high EE (>90%) and controlled release (10%). Biological evaluation studies revealed ACNPs as non-toxic to mouse neural stem cells (mNSCs). They displayed enhanced brain permeability and attenuated seizure. Our results confirmed ACNPs as effective in crossing the brain membrane barrier and mitigating seizure severity induced by PC.
A Novel Pythagorean Fuzzy Extension of DEMATEL and Its Usage on Overcoat Selection Attributes for Antarctic Clothing
Authors: Sivri Çağlar , Gül Sait , Aksu Ozan Rıdvan
Published: January 2022

Scientific explorations and research in the Antarctic region have specific issues which need to be handled with special measures. Clothing of the scientists is one of the main problems. The clothes are expected to be enduring against compelling conditions and they must have certain features to ensure the safety and comfort of the scientists. Polar clothing is a field that is yet to be studied with different engineering approaches. To generate a better understanding, the polar clothing can be approached as a multiple criteria decision-making problem because many criteria such as layer number, material type, and waterproofness should be considered while evaluating the various alternatives. In this evaluation, expert judgments are used because no strict objective rules determine the conditions of the polar clothing. Also, possible influences among these criteria should be revealed and considered while reaching a decision. In order to deal with the uncertainty and vagueness of the expert judgments, this study proposes a Pythagorean fuzzy version of DEMATEL which is one of the well-known multiple criteria decision-making tools with the aim of evaluating the related selection attributes affecting the decision and searching for the potential influences among them. Since Pythagorean fuzzy sets provide a wider preference domain to the experts, this version was developed as a contribution to the literature. Also, the decision process is kept Pythagorean fuzzy until a conclusion is reached so that there is no early defuzzification problem. The method’s application on overcoat selection for the Antarctic region reveals the relations among attributes, such as “Water Vapor Permeability”, “All-Weather Protection” and “Performing Best in Dry/Wet State”. A sensitivity analysis is conducted to find the changes in influences.
Fooling Polytopes
Authors: O’Donnell Ryan , Servedio Rocco A. , Tan Li-Yang
Published: January 2022

We give a pseudorandom generator that fools
m
-facet polytopes over {0, 1}

n

with seed length polylog(
m
) · log
n
. The previous best seed length had superlinear dependence on
m
.
BurstZ+: Eliminating The Communication Bottleneck of Scientific Computing Accelerators via Accelerated Compression
Authors: Sun Gongjin , Kang Seongyoung , Jun Sang-Woo
Published: January 2022

We present BurstZ+, an accelerator platform that eliminates the communication bottleneck between PCIe-attached scientific computing accelerators and their host servers, via hardware-optimized compression. While accelerators such as GPUs and FPGAs provide enormous computing capabilities, their effectiveness quickly deteriorates once data is larger than its on-board memory capacity, and performance becomes limited by the communication bandwidth of moving data between the host memory and accelerator. Compression has not been very useful in solving this issue due to performance and efficiency issues of compressing floating point numbers, which scientific data often consists of. BurstZ+ is an FPGA-based prototype accelerator platform which addresses the bandwidth issue via a class of novel hardware-optimized floating point compression algorithm called ZFP-V. We demonstrate that BurstZ+ can completely remove the host-side communication bottleneck for accelerators, using multiple stencil kernels with a wide range of operational intensities. Evaluated against hand-optimized implementations of kernel accelerators of the same architecture, our single-pipeline BurstZ+ prototype outperforms an accelerator without compression by almost 4×, and even an accelerator with enough memory for the entire dataset by over 2×. Furthermore, the projected performance of BurstZ+ on a future, faster FPGA scales to almost 7× that of the same accelerator without compression, whose performance is still limited by the PCIe bandwidth.
An Empirical Study of the Effectiveness of an Ensemble of Stand-alone Sentiment Detection Tools for Software Engineering Datasets
Authors: Uddin Gias , Guéhénuc Yann-Gaël , Khomh Foutse , Roy Chanchal K.
Published: January 2022

Sentiment analysis in
software engineering (SE)
has shown promise to analyze and support diverse development activities. Recently, several tools are proposed to detect sentiments in software artifacts. While the tools improve accuracy over off-the-shelf tools, recent research shows that their performance could still be unsatisfactory. A more accurate sentiment detector for SE can help reduce noise in analysis of software scenarios where sentiment analysis is required. Recently, combinations, i.e., hybrids of stand-alone classifiers are found to offer better performance than the stand-alone classifiers for fault detection. However, we are aware of no such approach for sentiment detection for software artifacts. We report the results of an empirical study that we conducted to determine the feasibility of developing an ensemble engine by combining the polarity labels of stand-alone SE-specific sentiment detectors. Our study has two phases. In the first phase, we pick five SE-specific sentiment detection tools from two recently published papers by Lin et al. [
29
,
30
], who first reported negative results with stand alone sentiment detectors and then proposed an improved SE-specific sentiment detector, POME [
29
]. We report the study results on 17,581 units (sentences/documents) coming from six currently available sentiment benchmarks for software engineering. We find that the existing tools can be complementary to each other in 85-95% of the cases, i.e., one is wrong but another is right. However, a majority voting-based ensemble of those tools fails to improve the accuracy of sentiment detection. We develop Sentisead, a supervised tool by combining the polarity labels and bag of words as features. Sentisead improves the performance (F1-score) of the individual tools by 4% (over Senti4SD [
5
]) – 100% (over POME [
29
]). The initial development of Sentisead occurred before we observed the use of deep learning models for SE-specific sentiment detection. In particular, recent papers show the superiority of advanced language-based
pre-trained transformer models (PTM)
over rule-based and shallow learning models. Consequently, in a second phase, we compare and improve Sentisead infrastructure using the PTMs. We find that a Sentisead infrastructure with RoBERTa as the ensemble of the five stand-alone rule-based and shallow learning SE-specific tools from Lin et al. [
29
,
30
] offers the best F1-score of 0.805 across the six datasets, while a stand-alone RoBERTa shows an F1-score of 0.801.
Do Developers Really Know How to Use Git Commands? A Large-scale Study Using Stack Overflow
Authors: Yang Wenhua , Zhang Chong , Pan Minxue , Xu Chang , Zhou Yu , Huang Zhiqiu
Published: January 2022

Git, a cross-platform and open source distributed version control tool, provides strong support for non-linear development and is capable of handling everything from small to large projects with speed and efficiency. It has become an indispensable tool for millions of software developers and is the de facto standard of version control in software development nowadays. However, despite its widespread use, developers still frequently face difficulties when using various Git commands to manage projects and collaborate. To better help developers use Git, it is necessary to understand the issues and difficulties that they may encounter when using Git. Unfortunately, this problem has not yet been comprehensively studied. To fill this knowledge gap, in this article, we conduct a large-scale study on Stack Overflow, a popular Q&A forum for developers. We extracted and analyzed 80,370 relevant questions from Stack Overflow, and reported the increasing popularity of the Git command questions. By analyzing the questions, we identified the Git commands that are frequently asked and those that are associated with difficult questions on Stack Overflow to help understand the difficulties developers may encounter when using Git commands. In addition, we conducted a survey to understand how developers learn Git commands in practice, showing that self-learning is the primary learning approach. These findings provide a range of actionable implications for researchers, educators, and developers.
A Framework for Adversarially Robust Streaming Algorithms
Authors: Ben-Eliezer Omri , Jayaram Rajesh , Woodruff David P. , Yogev Eylon
Published: January 2022

We investigate the adversarial robustness of streaming algorithms. In this context, an algorithm is considered robust if its performance guarantees hold even if the stream is chosen adaptively by an adversary that observes the outputs of the algorithm along the stream and can react in an online manner. While deterministic streaming algorithms are inherently robust, many central problems in the streaming literature do not admit sublinear-space deterministic algorithms; on the other hand, classical space-efficient randomized algorithms for these problems are generally not adversarially robust. This raises the natural question of whether there exist efficient adversarially robust (randomized) streaming algorithms for these problems.

In this work, we show that the answer is positive for various important streaming problems in the insertion-only model, including distinct elements and more generally

F
p

-estimation,

F
p

-heavy hitters, entropy estimation, and others. For all of these problems, we develop adversarially robust (1+ε)-approximation algorithms whose required space matches that of the best known non-robust algorithms up to a poly(log
n
, 1/ε) multiplicative factor (and in some cases even up to a constant factor). Towards this end, we develop several generic tools allowing one to efficiently transform a non-robust streaming algorithm into a robust one in various scenarios.
Detecting and Augmenting Missing Key Aspects in Vulnerability Descriptions
Authors: Guo Hao , Chen Sen , Xing Zhenchang , Li Xiaohong , Bai Yude , Sun Jiamou
Published: January 2022

Security vulnerabilities have been continually disclosed and documented. For the effective understanding, management, and mitigation of the fast-growing number of vulnerabilities, an important practice in documenting vulnerabilities is to describe the key vulnerability aspects, such as vulnerability type, root cause, affected product, impact, attacker type, and attack vector. In this article, we first investigate 133,639 vulnerability reports in the
Common Vulnerabilities and Exposures (CVE)
database over the past 20 years. We find that 56%, 85%, 38%, and 28% of CVEs miss vulnerability type, root cause, attack vector, and attacker type, respectively. By comparing the differences of the latest updated CVE reports across different databases, we observe that 1,476 missing key aspects in 1,320 CVE descriptions were augmented manually in the
National Vulnerability Database (NVD)
, which indicates that the vulnerability database maintainers try to complete the vulnerability descriptions in practice to mitigate such a problem.

To help complete the missing information of key vulnerability aspects and reduce human efforts, we propose a neural-network-based approach called
PMA
to predict the missing key aspects of a vulnerability based on its known aspects. We systematically explore the design space of the neural network models and empirically identify the most effective model design in the scenario. Our ablation study reveals the prominent correlations among vulnerability aspects when predicting. Trained with historical CVEs, our model achieves 88%, 71%, 61%, and 81% in F1 for predicting the missing vulnerability type, root cause, attacker type, and attack vector of 8,623 “future” CVEs across 3 years, respectively. Furthermore, we validate the predicting performance of key aspect augmentation of CVEs based on the manually augmented CVE data collected from NVD, which confirms the practicality of our approach. We finally highlight that PMA has the ability to reduce human efforts by recommending and augmenting missing key aspects for vulnerability databases, and to facilitate other research works such as severity level prediction of CVEs based on the vulnerability descriptions.
BiRD: Race Detection in Software Binaries under Relaxed Memory Models
Authors: Jain Ridhi , Purandare Rahul , Sharma Subodh
Published: January 2022

Instruction reordering and interleavings in program execution under relaxed memory semantics result in non-intuitive behaviors, making it difficult to provide assurances about program correctness. Studies have shown that up to 90% of the concurrency bugs reported by state-of-the-art static analyzers are false alarms. As a result, filtering false alarms and detecting real concurrency bugs is a challenging problem. Unsurprisingly, this problem has attracted the interest of the research community over the past few decades. Nonetheless, many of the existing techniques rely on analyzing source code, rarely consider the effects introduced by compilers, and assume a sequentially consistent memory model. In a practical setting, however, developers often do not have access to the source code, and even commodity architectures such as x86 and ARM are not sequentially consistent.

In this work, we present
B
i
rd
, a prototype tool, to dynamically detect harmful data races in x86 binaries under relaxed memory models, TSO and PSO.
B
i
rd
employs
source-DPOR
to explore all distinct feasible interleavings for a multithreaded application. Our evaluation of
B
i
rd
on 42 publicly available benchmarks and its comparison with the state-of-the-art tools indicate
B
i
rd
’s potential in effectively detecting data races in software binaries.
Adversarial Robustness of Deep Code Comment Generation
Authors: Zhou Yu , Zhang Xiaoqing , Shen Juanjuan , Han Tingting , Chen Taolue , Gall Harald
Published: January 2022

Deep neural networks (DNNs)
have shown remarkable performance in a variety of domains such as computer vision, speech recognition, and natural language processing. Recently they also have been applied to various software engineering tasks, typically involving processing source code. DNNs are well-known to be vulnerable to adversarial examples, i.e., fabricated inputs that could lead to various misbehaviors of the DNN model while being perceived as benign by humans. In this paper, we focus on the code comment generation task in software engineering and study the robustness issue of the DNNs when they are applied to this task. We propose
ACCENT
(Adversarial Code Comment gENeraTor)
, an identifier substitution approach to craft adversarial code snippets, which are syntactically correct and
semantically close to
the original code snippet, but may mislead the DNNs to produce completely irrelevant code comments. In order to improve the robustness,
ACCENT
also incorporates a novel training method, which can be applied to existing code comment generation models. We conduct comprehensive experiments to evaluate our approach by attacking the mainstream encoder-decoder architectures on two large-scale publicly available datasets. The results show that
ACCENT
efficiently produces stable attacks with functionality-preserving adversarial examples, and the generated examples have better transferability compared with the baselines. We also confirm, via experiments, the effectiveness in improving model robustness with our training method.
Atomic Embeddability, Clustered Planarity, and Thickenability
Authors: Fulek Radoslav , Tóth Csaba D.
Published: January 2022

We study the atomic embeddability testing problem, which is a common generalization of
clustered planarity
(
c-planarity
, for short) and thickenability testing, and present a polynomial-time algorithm for this problem, thereby giving the first polynomial-time algorithm for c-planarity.

C-planarity was introduced in 1995 by Feng, Cohen, and Eades as a variant of graph planarity, in which the vertex set of the input graph is endowed with a hierarchical clustering and we seek an embedding (crossing free drawing) of the graph in the plane that respects the clustering in a certain natural sense. Until now, it has been an open problem whether c-planarity can be tested efficiently. The thickenability problem for simplicial complexes emerged in the topology of manifolds in the 1960s. A 2-dimensional simplicial complex is thickenable if it embeds in some orientable 3-dimensional manifold. Recently, Carmesin announced that thickenability can be tested in polynomial time.

Our algorithm for atomic embeddability combines ideas from Carmesin’s work with algorithmic tools previously developed for weak embeddability testing. We express our results purely in terms of graphs on surfaces, and rely on the machinery of topological graph theory.

Finally, we give a polynomial-time reduction from atomic embeddability to thickenability thereby showing that both problems are polynomially equivalent, and show that a slight generalization of atomic embeddability to the setting in which clusters are toroidal graphs is NP-complete.
Events
Authors: Samarasinghe Dilini
Published: January 2022

This section features information about upcoming events relevant to the readers of AI Matters, including those supported by SIGAI. We would love to hear from you if you are are organizing an event and would be interested in cooperating with SIGAI.For more information about conference support visit sigai.acm.org/activities/requesting sponsorship. html.
Huanchen Zhang Speaks Out on Memory-Efficient Search Trees
Authors: Winslett Marianne , Braganholo Vanessa
Published: January 2022

Welcome to ACM SIGMOD Record's series of interviews with distinguished members of the database community. I'm Marianne Winslett, and today I have here with me Huanchen Zhang, who is the 2021 winner of the ACM SIGMOD Jim Gray Dissertation Award for his thesis entitled Memory-Efficient Search Trees for Database Management Systems. After a postdoc at Snowflake, Huanchen is now an Assistant professor at Tsinghua University. His PhD is from Carnegie Mellon University, where he worked with David Andersen and Andy Pavlo. So, Huanchen, welcome!
Improved Oxygen Evolution and Oxygen Reduction Behavior of NiCo2O4: Revisiting the Use of Mesocarbon Microbeads
Authors: Jao Wen-Yang , Lu Yi-Ting , Lai Chi-Yu , Hu Chi-Chang
Published: January 2022

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital to the operation of rechargeable zinc-air batteries. This work demonstrates that both the intrinsic activity and the electrochemically active surface area (ECSA) of the oxide-carbon composites are key factors determining the overall catalytic activity. Here, we revisit the possible use of mesocarbon microbeads (MCMBs) as a support to improve the bifunctional activity of NiCo2O4 (NCO). Pre-treatments including oxidation and expansion of MCMB have been applied to obtain two types of modified MCMBs. The abundant functional groups on the oxidized MCMB (OMCMB) provide strong interaction between oxide and carbon, although a relatively low electrical conductivity is obtained. Compared to OMCMB, the expanded MCMB (EMCMB) with less functional groups shows a much larger surface area and presumably higher conductivity. The three-electrode tests reveal that the composite supported by OMCMB-3h (i.e., 3-h oxidation treatment) has a moderate intrinsic activity of the OER and the highest ECSA, leading to the enhanced bifunctional activities. The charge-discharge test of a rechargeable zinc-air battery at various current densities shows the cycling stability of NCO/OMCMB-3h at 150 mA cm−2, which also can be cycled at 15 mA cm−2 for 60 h without obvious decay.