bluuebunny/crossref_metadata_2025 huggingface dataset:
Silica‐rich seawater in the early Cambrian: Sedimentological evidence from bedded cherts
Authors: Zhou Xiqiang , Chen Daizhao , Zhang Liyu , Tang Dongjie , Guo Chuan
Published: May 2021

The effects and timing of the evolution of siliceous sponge and radiolarians on the mode of silica burial and oceanic silica cycling in the early Cambrian are still controversial. Bedded cherts of the lower Cambrian Yurtus Formation deposited in a subtidal shelf environment. They display diagnostic sedimentary features, including intraclastic chert grains, edgewise chert breccias, weakly compacted grains and rip‐up clasts, and rapid silica cementation, collectively indicating primary and very early silicification at and near the sediment–water interface. This depositional mode contrasts with Phanerozoic biogenic cherts but is comparable with that of Precambrian cherts precipitated from silica‐rich seawater. The Yurtus cherts therefore provide direct and compelling sedimentological evidence of the continuation of silica‐rich seawater into the early Cambrian, consistent with the extensive coeval chert depositions elsewhere. These results contrast with the long‐held view of rapid decline in seawater silica concentrations in the earliest Phanerozoic, and elucidate coeval Si‐coupled geochemical cycling, silica‐biomineralization and fossil preservation.
Association of household wealth and education level with hypertension and diabetes among adults in Bangladesh: a propensity score‐based analysis
Authors: Gupta Rajat Das , Chakraborty Promit Ananyo , Hossain Md. Belal
Published: May 2021

Objective

To determine the association of household wealth and education level with hypertension and diabetes in Bangladesh using propensity score (PS) analyses.

Methods

A nationally representative sample of the Bangladesh Demographic and Health Survey 2017–18 was analysed to explore the research question. A weighted sample of 11 320 individuals was considered. Hypertension and diabetes were the outcomes of interest, and household wealth status (non‐poor and poor) and education level (secondary/higher education and no secondary/higher education) were the exposure variables of interest. A person was defined as hypertensive if their average blood pressure was ≥140/90 mmHg or self‐reported history of taking antihypertensive medications. Individuals were classified as diabetic if they had a Fasting Blood Glucose level of ≥7 mmol/l or reported taking prescribed medication for reducing high blood glucose or diabetes. We used the 1:1 nearest neighbour PS matching without replacement and PS weighting approaches to assess the association between the exposures and the outcome variables.

Results

Wealth status was significantly associated with diabetes but not with hypertension, while education status was significantly associated with neither diabetes nor hypertension. We also observed a significant interaction effect between household wealth status and education level with diabetes. The odds of diabetes were approximately 60% higher among adults from non‐poor households and those without secondary/higher education.

Conclusion

Diabetes prevention and control programs should focus on non‐poor individuals, while hypertension prevention programs should target populations irrespective of educational attainment and wealth status.
Active case finding of pulmonary TB in a European refugee camp: lessons learnt from Oinofyta hosting site in Greece
Authors: Solomos Zisimangelos , Botsi Chrisoula , Georgakopoulou Theano , Lytras Theodore , Tsiodras Sotirios , Puchner Karl Philipp
Published: May 2021

Objectives

To report on an active case finding (ACF) intervention that took place in the migrant camp of Oinofyta, Greece, upon suspicion of active TB transmission.

Methods

Upon diagnosis of 3 TB cases among camp residents, an ACF intervention among contacts was implemented. All camp residents were offered two‐step screening, that is tuberculin skin testing (TST) followed by chest X‐ray in case of positive TST (defined as ≥5 mm).

Results

336 of 379 (89%) camp residents underwent TST testing, of whom 110 (33%) exhibited a positive skin reaction. The rate of positive TST results was particularly high in the elderly and significantly higher in adults than in children. Differences by sex or nationality were not observed. Of the 110 cases with positive TST, only 75 underwent chest X‐ray, resulting in the detection of one pulmonary TB case in an adult woman.

Conclusions

In the given intervention context, two‐step ACF proved to be operationally cumbersome, with many residents lost to follow‐up and a high Number Needed to Screen. Simpler ACF designs should be pilot‐tested in similar settings in the future, and blanket screening of all camp residents should be reconsidered. Conclusions drawn by these exercises should pave the way for adopting a comprehensive, context‐specific and evidence‐based national strategy on TB in migrants.
Moving from crisis to critical praxis: Geography in South Africa
Authors: Daya Shari
Published: May 2021

In this short commentary, I explore some recent shifts in the landscape of South African higher education, from the vantage point of my particular location within Geography at the University of Cape Town. Although those of us working in this context have experienced multiple challenges in recent years, I argue here that we could usefully re‐frame the ongoing state of crisis as a moment of opportunity in which we might both revitalise critical geographical work and engender more just cultures of academic praxis, premised on relationships of care. In particular, Geography could productively engage more directly, in both its theory and its praxis, with Southern and decolonial scholarship as well as postcolonial and feminist thought. Such a move would deepen our understanding of where we are, how we got here, and how we might build more equitable relationships. It would help us to see the world more clearly and imagine alternatives more effectively, from our diverse locations on the African continent.
Impact of the early coronavirus disease 2019 pandemic on blood utilization in the United States: A time‐series analysis of data reported to the National Healthcare Safety Network Hemovigilance Module
Authors: Kracalik Ian , Mowla Sanjida , Katz Louis , Cumming Melissa , Sapiano Matthew R. P. , Basavaraju Sridhar V.
Published: May 2021

Introduction

The coronavirus disease 2019 (COVID‐19) pandemic has disrupted healthcare services worldwide. However, little has been reported regarding the impact on blood utilization. We quantified the impact of COVID‐19 on blood utilization and discards among facilities reporting to the National Healthcare Safety Network Hemovigilance Module.

Methods

Facilities continuously reporting data, during January 2016–June 2020, on transfused and discarded blood components, stratified by component type (red blood cells [RBC], platelets, and plasma), were included. Interrupted time‐series analysis with generalized estimating equations, adjusting for facility surgical volume and seasonality, was used to quantify changes in blood utilization and discards relative to a Centers for Medicare & Medicaid Services notification delaying nonessential medical procedures (March 2020).

Results

Seventy‐two facilities included in the analyses, on average, transfused 44,548 and discarded 2,202 blood components monthly. Following the March 2020 notification and after multivariable adjustment, RBC and platelet utilization declined, −9.9% (p < .001) and −13.6% (p = .014), respectively. Discards increased for RBCs (30.2%, p = .047) and platelets (60.4%, p = .002). No statistically significant change in plasma was found. Following these abrupt changes, blood utilization and discards rebounded toward baseline with RBC utilization increasing by 5.7% (p < .001), and platelet and RBC discards decreasing −16.4% (<0.001) and −12.7 (p = .001), respectively.

Conclusion

Following notification delaying elective surgical procedures, blood utilization declined substantially while blood discards increased, resulting in substantial wastage of blood products. Ongoing and future pandemic response efforts should consider the impact of interventions on blood supply and demand to ensure blood availability.
Global supply chains, trade agreements and rules of origin
Authors: Tsirekidze David
Published: May 2021

Free Trade Agreements (FTAs) usually come with restrictions on the use of intermediate inputs in order for final goods to qualify for free trade. I focus on Rules of Origin (RoO), which limit expenses on nonmember country's intermediate inputs. In a three‐country FTA formation game, I introduce international trade in intermediate inputs and RoO restrictions. In the case of symmetric countries, I show that as countries become more involved in global supply chains, measured by their input shares in foreign final goods production, global free trade is less likely to be a stable equilibrium outcome. Free riding is the main problem preventing countries from liberalising trade. Countries are better off being nonmembers of FTAs between the other two countries relative to global free trade. Rules of Origin can solve this problem by limiting the benefits countries get from other countries' free trade agreements. In the case of asymmetric countries, an additional incentive exists for the smaller country not to join: such a country gives up more than it gains from joining an FTA for a sufficiently high degree of asymmetry in country sizes. I show that global free trade is a stable Nash equilibrium under a larger region of asymmetric country parameter space in the case of RoO than without it. Therefore, it is shown that RoO is essential in order to attain global free trade.
Examining the effect of wound cleansing on the microbiome of venous stasis ulcers
Authors: Ernlund Amanda W. , Moffatt Lauren T. , Timm Collin M. , Zudock Kristina K. , Howser Craig W. , Blount Kianna M. , Alkhalil Abdulnaser , Shupp Jeffrey W. , Karig David K.
Published: May 2021

Common treatment for venous leg wounds includes topical wound dressings with compression. At each dressing change, wounds are debrided and washed; however, the effect of the washing procedure on the wound microbiome has not been studied. We hypothesized that wound washing may alter the wound microbiome. To characterize microbiome changes with respect to wound washing, swabs from 11 patients with chronic wounds were sampled before and after washing, and patient microbiomes were characterized using 16S rRNA sequencing and culturing. Microbiomes across patient samples prior to washing were typically polymicrobial but varied in the number and type of bacterial genera present.ProteusandPseudomonaswere the dominant genera in the study. We found that washing does not consistently change microbiome diversity but does cause consistent changes in microbiome composition. Specifically, washing caused a decrease in the relative abundance of the most highly represented genera in each patient cluster. The finding that venous leg ulcer wound washing, a standard of care therapy, can induce changes in the wound microbiome is novel and could be potentially informative for future guided therapy strategies.
Electroporation-Based Therapy for Brain Tumors: A Review
Authors: Fang Zheng , Chen Lingchao , Moser Michael A. J. , Zhang Wenjun , Qin Zhiyong , Zhang Bing
Published: May 2021

Electroporation-based therapy (EBT), as a high-voltage-pulse technology has been prevalent with favorable clinical outcomes in the treatment of various solid tumors. This review paper aims to promote the clinical translation of EBT for brain tumors. First, we briefly introduced the mechanism of pore formation in a cell membrane activated by external electric fields using a single cell model. Then, we summarized and discussed the current in vitro and in vivo preclinical studies, in terms of (1) the safety and effectiveness of EBT for brain tumors in animal models, and (2) the blood-brain barrier (BBB) disruption induced by EBT. Two therapeutic effects could be achieved in EBT for brain tumors simultaneously, i.e., the tumor ablation induced by irreversible electroporation (IRE) and transient BBB disruption induced by reversible electroporation (RE). The BBB disruption could potentially improve the uptake of antitumor drugs thereby enhancing brain tumor treatment. The challenges that hinder the application of EBT in the treatment of human brain tumors are discussed in the review paper as well.
Dynamic Characteristics Analysis of a Seal-Rotor System With Rub-Impact Fault
Authors: Luo Yuegang , Wang Pengfei , Jia Haifeng , Huang Fengchao
Published: May 2021

Labyrinth seals are widely used to prevent fluid leakage in high-low pressure areas of the rotating machinery. However, the rub-impact fault easily occurs in labyrinth seals. Considering the influence of gyroscopic effect, a finite element model of seal-rubbing rotor system is established in this study based on the Muszynska seal force model, the rolling bearing force model, and the nonlinear rubbing force model. The vibration characteristics under the coupling faults of airflow excitation and rub-impact are analyzed. First, the response of the system without rub-impact fault is simulated numerically and verified by experiments. Subsequently, the dynamic characteristics of the rotor under the conditions of slight and severe rub-impact faults are analyzed. Finally, the influence of the rub-impact parameters is further studied. The results indicate that when the rub-impact fault is absent, airflow excitation occurs at a certain speed, which exhibits the characteristics of frequency locking and combination frequency. The coupling dynamic responses of airflow-induced vibration and rub-impact fault show a rich spectrum of nonlinear phenomena, which are closely related to the degree of rub impact. This study may provide a theoretical basis for the detection and diagnosis of fluid-induced rub-impact fault in labyrinth seal-rotor systems.
Evaluation of the Relation Between Preload Values and Pull-Out Force of the Cortical Screw Used in Bone Fracture
Authors: Çelik Talip
Published: May 2021

This study aims to examine the relation between pull-out strength and preload values of the cortical screw used in bone fracture fixation. The research question is that “Does the pull-out strength of the cortical screw used in the bone fracture fixation change with the preload values of the screw change?”. To perform this purpose, the finite element method was selected due to its ease to evaluate and calculate the stresses on the whole model. Models of a cortical screw, partial plate, and bone were created using the SolidWorks program. The material properties of the bone were selected orthotropic material type. The bone fixed on the distal and proximal ends. The pull-out forces were applied at the bottom of the plate. The screw that has been loaded ranges from 100 N–700 N as preload. The pull-out forces were determined 200–400–600 N as in the literature. The results show that the pull-out strength of the screw was changed when the preloaded values higher than 400 N. However, it was seen that the pull-out strength does not substantially change when the preload values were lower than 400 N. When the preload values were applied ≥500 N, the maximum von Mises stresses on the screw exceeded the critical strength of the screw material. In conclusion, the critical preload value was determined as 500 N for the optimum pull-out strength.
Design Optimization of a Novel Multifiring Clip Applicator System for Endoscopic Closure of Large Perforations
Authors: Ai Liaoyuan , Song Chengli , Mao Lin , Ge Shuchen , Pan Zhen
Published: May 2021

Endoscopic closure has become the first choice for closing iatrogenic perforations. Previously, we reported a self-developed endoscopic multifiring clip applicator (EMFCA) system. In this paper, a new EMFCA system for endoscopic closure of large perforations with a redesigned clip, the less traumatic grasper, and a highly efficient driving system was presented, and its efficacy was evaluated. The behaviors of the new clip and grasper were verified through finite element analysis (FEA). The capability of pushing transmission for the EMFCA system was identified by the proposed model and the validation experiment. Ex-vivo studies were conducted on porcine stomachs to compare the outcomes of the closures. The FEA results showed that the deformation of the clip was safe and smoother, with a maximum stress of 640.0 MPa. The less traumatic grasper could increase the grasping force and avoid trauma by exerting uniform stress along the axis. The capability of pushing transmission was enhanced by the double-nested tendon-sheath actuation system with an efficiency of 0.45–0.48. The mechanical strength, the leakage pressure, and the operating time for the closures with the new EMFCA system and the previous EMFCA system were 6.1 N ± 0.8 N, 37.1 mmHg ± 6.8 mmHg, 7.3 min ± 0.4 min and 5.1 N ± 1.0 N, 27.4 mmHg ± 6.4 mmHg, 11.4 min ±0.8 min, respectively. The new EMFCA system can realize a superior, reliable, and high-efficiency endoscopic closure of large perforations.
Air-Water Flow Properties in Hydraulic Jumps With Fully and Partially Developed Inflow Conditions
Authors: Montano Laura , Felder Stefan
Published: May 2021

Novel air–water flow measurements were conducted in fully aerated hydraulic jumps with partially and fully developed supercritical inflow conditions. Irrespective of the inflow conditions, the hydraulic jumps resembled typical flow patterns with strong aeration and instabilities, albeit hydraulic jumps with fully developed inflow conditions had a more upward directed roller motion and a larger clear water core in the second half of the roller. Hydraulic jumps with fully developed inflow conditions had comparatively larger void fractions in the first half of the jump roller and larger bubble count rates throughout, while a comparatively larger number of smaller bubble sizes suggested a stronger break-up of bubbles. This was consistent with slightly larger interfacial velocities and turbulence intensities in the first half of the jump roller with fully developed inflow conditions. An assessment of the required sampling duration for air–water flow properties indicated the requirement to sample for at least five times longer than applied in previous studies. These results highlighted the need to carefully consider the inflow conditions and sampling parameters for aerated hydraulic jumps.
The magnetic moment of $$P_{c}(4312)$$ as a $$\bar{D}\Sigma _{c}$$ molecular state
Authors: Xu Yong-Jiang , Liu Yong-Lu , Huang Ming-Qiu
Published: May 2021

In this paper, we tentatively assign the $$P_{c}(4312)$$

P
c

(
4312
)

to be a $$\bar{D}\Sigma _{c}$$

D

¯

Σ
c

molecular state with quantum number $$J^{P}=\frac{1}{2}^{-}$$

J
P

=

1
2

-

, and calculate its magnetic moment using the QCD sum rule method in external weak electromagnetic field. Starting with the two-point correlation function in external electromagnetic field and expanding it in power of the electromagnetic interaction Hamiltonian, we extract the magnetic moment from the linear response to the external electromagnetic field. The numerical value of the magnetic moment of $$P_{c}(4312)$$

P
c

(
4312
)

is $$\mu _{P_{c}}=1.75^{+0.15}_{-0.11}$$

μ

P
c

=
1
.

75

-
0.11

+
0.15

.
Weyl consistency conditions from a local Wilsonian cutoff
Authors: Ellwanger Ulrich
Published: May 2021

A local UV cutoff $$\Lambda (x)$$

Λ
(
x
)

transforming under Weyl rescalings allows to construct Weyl invariant kinetic terms for scalar fields including Wilsonian cutoff functions. First we consider scalar fields in curved space-time with local bare couplings of any canonical dimension, and anomalous dimensions which describe their dependence on the UV cutoff. The local component of the UV cutoff plays the role of an additional coupling, albeit with a trivial constant $$\beta $$
β
function. This approach allows to derive Weyl consistency conditions for the corresponding anomalous dimensions which assume the form of an exact gradient flow. For renormalizable theories the Weyl consistency conditions are initially of the form of an approximate gradient flow for the $$\beta $$
β
functions, and we derive conditions under which it becomes the form of an exact gradient flow.
Effects of temperature variations in high-sensitivity Sagnac gyroscope
Authors: Basti Andrea , Beverini Nicolò , Bosi Filippo , Carelli Giorgio , Ciampini Donatella , Di Virgilio Angela D. V. , Fuso Francesco , Giacomelli Umberto , Maccioni Enrico , Marsili Paolo , Passeggio Giuseppe , Porzio Alberto , Simonelli Andreino , Terreni Giuseppe
Published: May 2021

GINGERINO is one of the most sensitive Sagnac laser-gyroscopes based on an heterolithic mechanical structure. It is a prototype for GINGER, the laser gyroscopes array proposed to reconstruct the Earth rotation vector and in this way to measure General Relativity effects. Many factors affect the final sensitivity of laser gyroscopes, in particular, when they are used in long-term measurements, slow varying environmental parameters come into play. To understand the role of different terms allows to design more effective mechanical as well as optical layouts, while a proper model of the dynamics affecting long-term (low frequency) signals would increase the effectiveness of the data analysis for improving the overall sensitivity. In this contribution, we focus our concerns on the effects of room temperature and pressure aiming at further improving mechanical design and long-term stability of the apparatus. Our data are compatible with a local orientation changes of the Gran Sasso site below $$\mu $$
μ
rad as predicted by geodetic models. This value is consistent with the requirements for GINGER and the installation of an high-sensitivity Sagnac gyroscope oriented at the maximum signal, i.e. along the Earth rotation axes.
Error-Free Affine, Unitary, and Probabilistic OBDDs
Authors: Ibrahimov Rishat , Khadiev Kamil , Prūsis Krišjānis , Yakaryılmaz Abuzer
Published: May 2021

We introduce the affine OBDD model and show that zero-error affine OBDDs can be exponentially narrower than bounded-error unitary and probabilistic OBDDs on certain problems. Moreover, we show that Las-Vegas unitary and probabilistic OBDDs can be quadratically narrower than deterministic OBDDs. We also obtain the same results for the automata counterparts of these models.
Existence and uniqueness of inhomogeneous ruled hypersurfaces with shape operator of constant norm in the complex hyperbolic space
Authors: Domínguez-Vázquez Miguel , Pérez-Barral Olga
Published: May 2021

We complete the classification of ruled real hypersurfaces with shape operator of constant norm in nonflat complex space forms by showing the existence of a unique inhomogeneous example in the complex hyperbolic space.
On local hulls of Levi-flat hypersurfaces
Authors: Shafikov Rasul , Sukhov Alexandre
Published: May 2021

We discuss local polynomial convexity of real analytic Levi-flat hypersurfaces in [Formula: see text], [Formula: see text], near singular points.
Thermodynamics and heat engines of black holes with Born–Infeld-type electrodynamics
Authors: Balart Leonardo , Fernando Sharmanthie
Published: May 2021

In this paper, we have studied electrically charged black holes in a new model of nonlinear electrodynamics introduced by Kruglov in Mod. Phys. Lett. A 32, 1750201 (2017). There are two parameters for the theory and the black hole could have up to two horizons. Thermodynamics is studied in the extended phase space where the pressure is proportional to the cosmological constant. First law and the Smarr formula are derived. There are phase transitions similar to the Van der Waals liquid-gas phase transitions. Black hole is also studied as a heat engine and we have discussed how the parameters in the nonlinear electrodynamics theory affect the efficiency of the heat engine.
CNT/epoxy interleaves for strengthening performance of filament wound composite structures
Authors: Park Soo-Jeong , Kim Yun-Hae
Published: May 2021

The failure mechanism of composites dominates the matrix, fiber and interface, and in general, the matrix corresponds to the definitive cause of damage. A filament–wound composite structure involves a notable bridging effect owing to the matrix between the layers, and particle additives are generally adopted to strengthen the matrix. However, particle additives exhibit a low performance when applied to structures, owing to the dispersibility and particle agglomeration. In this study, the strengthening performance of carbon nanotube (CNT)/epoxy interleaves was experimentally verified to facilitate their implementation in the structural design of a filament–wound cylinder structure. The burst pressure, compression, bending and interfacial bonding strength of the cylinder improved by approximately 20%, 161%, 16% and 36%, respectively, and the positioning of CNT/epoxy interleaves was a more notable influencing factor compared to the proportion of CNTs in the entire winding layer. The number of macro voids decreased inside the epoxy modified CNT. The findings demonstrated that the incorporation of CNTs through CNT/epoxy interleaves could facilitate the matrix strengthening and enhance the interfacial bonding.
A study on the removal of paint and oxide layer on the steel surface by laser beam scanning method
Authors: Kim Ji-Eon , Kim Jong-Do
Published: May 2021

In this study, a laser cleaning method was developed in order to replace the existing manual work-based technologies. The experimental investigation analyzed the cleaning properties of the paint and the oxide layer on the steel surface according to the laser beam scanning method. Experiments showed that in the cleaning process, the line beam patterns with a moving stage showed differences in heat input depending on the area, and the square area beam patterns obtained with control of a Galvano scanner showed uniform cleaning performance. The results of this study demonstrated that through the prosed laser cleaning technique, oxide layers as well as paint on steel surfaces can be removed with excellent precision, which is expected to be useful in the development of eco-friendly surface cleaning techniques.
Temperature measurement of turbulent flame using CT-TDLAS (computed tomography-tunable diode laser absorption spectroscopy)
Authors: Jeon Min-Gyu , Hong Jeong-Woong , Doh Deog-Hee , Deguchi Yoshihiro
Published: May 2021

In order to satisfy the requirements of high-quality and high-performance optimal material manufacturing process, it is essential to control the gas system of the manufacturing process. In the actual industry, the quality of products is improved by controlling various gases in the manufacturing process. The tunable laser absorption spectroscopy (TDLAS) technique can be measured by the temperature and concentration of target gas simultaneously. Among the more advanced technologies, CT-TDLAS is the most crucial technique for measuring temperature and concentration distributions across two-dimensional planes. This study suggests a three-dimensional useful measurement of irregular flow or exhaust gases. Furthermore, an optical measurement method has been adopted to measure temperature distribution at a cross-section of the Methane Air premixed turbulent flame. The equivalence ratio of fuel can control this system. The burner system consists of two sections (main flame, sub-flame) for a turbulent flame. In the CT-TDLAS technique, it is essential to set the wavelength for target gases. There is a limit to high-temperature measurement in temperature estimation using a single laser-specific wavelength. Therefore, compared measurement performance was made using a mixed type laser (1388 nm, 1343 nm) and a single type laser (1388 nm). The temperatures obtained by using the optical measurement results were relatively evaluated with those obtained by the thermocouples. It was confirmed that the relative error of the temperature occurred at the central position of the burner. It was about 13.33% by the mixed laser system and 38.33% by the single laser system in most close to point from the burner.
Development of multi-layered sewer pipe plug — 1st report: Ruptured test and stress analysis of protective sheet
Authors: Noda Nao-Aki , Tottori Hisanori , Gao Geng , Takaki Rei , Sano Yoshikazu , Kai Akira
Published: May 2021

In recent years, the sewer system in Japan is becoming obsolete. It is, therefore, necessary to reinforce or repair without stopping sewer functions by applying a suitable water stopping method. In this study, a multi-layered sewer pipe plug consisting of a protective sheet and inner and outer rubber balls is focused since it can be installed and removed at the construction site in a short time conveniently. This sewer pipe plug has several advantages dealing with various diameters compared to the conventional type. In this study, the rupture test is conducted to improve the water stopping performance. The fractured position of the protective sheet of the sewer pipe plug is investigated experimentally. It is clarified that the maximum stress around the flange portion can be reduced by decreasing the flange inner diameter.
Effect of focal position on cut surface quality in laser cutting of 50-mm thick stainless steel
Authors: Song Moo-Keun , Kim Jong-Do , Shin Dong-Sig , Lee Su-Jin , Cho Dae-Won
Published: May 2021

In this study, the parameters for underwater laser cutting of 50-mm thick stainless steel, which is typically used in nuclear power structures, are investigated. The focal position of laser beam significantly affects the cutting quality. In particular, in the cutting of the thick sample, change in the focal position determines the kerf width and the roughness of the cut surface. Moreover, the effects of the variation of kerf width and the cut surface characteristics on the focal position of the laser beam are investigated. As the focal position moved to the inside of the material, the upper kerf width increased, but the quality of the cut surface was improved.
Fabrication and characterization of flexible hybrid transparent electrodes with broadband transparency
Authors: Lin Keh-Moh , Shinde Swapnil , Lin Ru-Li , Hsiao Wen-Tse , Koinkar Pankaj
Published: May 2021

In this study, indium-zinc oxide (IZO)/silver (Ag)/IZO (ZAZ) flexible transparent electrodes were prepared on polyethylene terephthalate substrate using radio frequency sputtering technique. Experimental results showed that when the Ag film transited from semi-continuous state to continuous state, the ZAZ electrode exhibited high optoelectronic performance. The best ZAZ sample had a quite wide range of high transmittance and an average transmittance of 78.9% in visible light region, and sheet resistance of [Formula: see text]/sq and a Haacke Index of [Formula: see text]. The bending test revealed that the [Formula: see text] (change in sheet resistance) of ZAZ electrodes after 1000 bends was still less than 25% while the electrical properties of IZO films deteriorated after only 100 bending tests.
Fatigue strength improvement of roller chain by press fitting between pin and plate
Authors: Saito Ryoichi , Noda Nao-Aki , Sano Yoshikazu , Miyagi Arata , Okamura Tomoaki
Published: May 2021

To improve the fatigue strength of the roller chain, the fatigue test is conducted by varying the press-fitting ratio between the pin and the holed plate. To model what occurs in a chain under load, a single plate specimen is prepared by press-fitting two pins into two holes at the ends of the plate. The FEM analysis is performed to obtain the stress amplitude and the average stress. The results, in both cases demonstrate that the fatigue strength is improved by the press-fit between the pin and the hole. The fatigue improvement mechanism is discussed based on the stress analysis.
Study of the micro/nano-texture design to improve the friction properties of DLC thin films
Authors: Kwon Young Woo , Bae Mun Ki , Murakami Ri-Ichi , Jang Tae Hwan , Kim Tae Gyu
Published: May 2021

In this study, a DLC pattern was fabricated through a photolithography process that constitutes a part of the semiconductor process, to investigate the frictional wear characteristics. The photolithography was used to produce negative patterns with a pattern width of 10 [Formula: see text]m or 20 [Formula: see text]m and a pattern depth of 500 nm on the DLC surface. The change in the coefficient of friction of the surface was investigated through a ball-on-disk tribology test on the fabricated micro/nano-sized DLC pattern. The DLC pattern fabricated by the photolithography process showed a superior coefficient of friction to that of the general DLC sample. These results show that the decrease in the surface friction coefficient of the patterned DLC thin film is due to the reduction in the surface contact area owing to the modification of the micro/nano-texture of the surface as well as the low friction characteristics of the DLC.
A novel system for measuring vehicle speed via analog signals of pyroelectric infrared sensors
Authors: Quang Vu Van , Thang Vu Toan
Published: May 2021

This paper presents a method of measuring transportation vehicle’s speed via analog signals of a couple of pyroelectric infrared sensors. The measuring system is located along the roadside with the assumption that optical axes of the sensors are parallel to each other and perpendicular to the moving direction of vehicles. A cross-correlation method combined with interpolation has been used in order to determine the time delay between two output signals, thus defining the traveling speed of the target. The experiment results show that the proposed method has an error of less than 5 km/h over the speed range of 20–90 km/h.
Accurate stress intensity factors for kinked interface crack in bonded dissimilar half-plane
Authors: Oda Kazuhiro , Noda Nao-Aki
Published: May 2021

In this study, the stress intensity factor (SIF) of an interface kinked crack is analyzed by the singular integral equation of the body force method. The problem can be expressed by distributing the body force doublets of the tension and shear types along all the boundaries of the kinked and interface crack parts. The SIFs can be obtained directly from the densities of the body force doublets at the crack tips. Although the problem has already been calculated using the crack connection model, the accuracy of the analysis has not been clarified. From the analysis results in this study, it can be seen that the SIFs calculated by the crack connection model have a nonnegligible error, and the present method gives more accurate results. The advantage of the present method is that the SIFs of the kinked and the interface crack tips can be obtained at the same time with high accuracy.
Electrophoretic deposition of non-conductive halloysite nanotubes onto glass fabrics with improved interlaminar properties of glass/epoxy composites
Authors: Yu Tianyu , Chen Zixuan , Park Soo-Jeong , Kim Yun-Hae
Published: May 2021

This study achieved a homogeneous hierarchical distribution of non-conductive halloysite nanotubes (HNTs) on unidirectional glass fabrics using electrophoretic deposition (EPD). Silane modification was successfully applied to HNTs and glass fabrics. The HNTs and glass fabrics were covalently bonded by condensation polymerization between the carboxyl and amino groups during the EPD process. The HNT-grafted glass fabrics were fabricated into glass fiber-reinforced polymers (GFRPs) using vacuum-assisted resin transfer molding. These results demonstrate an effective enhancement in the through-thickness of HNT-grafted GFRPs. The enhanced mechanical properties of the hierarchically and covalently distributed HNTs were attributed to the excellent interfacial bonding and nanobridging of the HNTs.
Breaking theory of solitary waves for the Riemann wave equation in fluid dynamics
Authors: Duran Serbay
Published: May 2021

In this study, analytical solutions and physical interpretations are presented for the Riemann wave equation (RWE), which has an important physical property in fluid dynamics. The solutions of the RWE, which models the formation, interaction and breaking of the waves that occur as a result of any external effect on the ocean surface, are examined using the generalized exponential rational function method (GERFM). Bright (nontopological) soliton, singular soliton and solitary wave solutions are produced with advantages of GERFM over other traditional exponential methods. The factors in which solitary wave solutions cause breaking of wave are examined. The effects of parameters on wavefunctions and the physical interpretations of these effects are discussed and supported by graphics and simulations.
An extended lattice hydrodynamic model considering the average optimal velocity effect field and driver’s sensory memory
Authors: Zheng Yaxing , Ge Hongxia , Cheng Rongjun
Published: May 2021

A modified lattice hydrodynamic model is proposed by considering the driver’s sensory memory and the average optimal velocity effect field. The stability conditions of the novel model are further analyzed theoretically through the linear analysis. The nonlinear modified Korteweg–de Vries (mKdV) equation near the critical point is obtained, which can describe the jamming transition of traffic flow properly. Numerical simulations for the novel model are carried out and the results validate that the traffic jam can be suppressed efficiently by considering the average optimal velocity effect field and driver’s sensory memory. Besides, the energy consumption simulation is devised to investigate the stability of the traffic system. Eventually, PMES data is adopted to calibrate and evaluate the parameters of the proposed model, which proves that it precisely reflects the evolution of traffic flow. All the simulation results verify the feasibility and validity of this model.
The effect of Er doping on the crystallization of Ge1−xSnx thin films
Authors: Xia Baijie , Dong Zhaoshi , Zhao Chunwang
Published: May 2021

The Er-doped [Formula: see text] thin films with different Sn contents were prepared on Ge buffered Si substrates by thermal evaporation. The effect of Er doping on the crystallization of [Formula: see text] films at different annealing temperatures was studied. It is demonstrated that Er doping can increase the critical crystallization temperature and greatly reduce the surface roughness of high temperature annealed [Formula: see text] thin films.
An algorithm for computing a supercharacter theory generated from a given partition
Authors: Burkett Shawn T.
Published: May 2021

Let [Formula: see text] be a finite group. The set of all supercharacter theories of [Formula: see text] forms a lattice, where the join operation coincides with the join operation on the lattice of partitions of [Formula: see text], with partial order given by refinement. The meet operation is more complicated however, and seems difficult to describe. In this paper, we outline algorithms for determining the coarsest supercharacter theory whose associated partition is finer than a given partition. One of the primary applications is to compute the supercharacters and superclasses for the meet of two supercharacter theories.
Symbolic powers of cover ideals of graphs and Koszul property
Authors: Gu Yan , Hà Huy Tài , Skelton Joseph W.
Published: May 2021

We show that attaching a whisker (or a pendant) at the vertices of a cycle cover of a graph results in a new graph with the following property: all symbolic powers of its cover ideal are Koszul or, equivalently, componentwise linear. This extends previous work where the whiskers were added to all vertices or to the vertices of a vertex cover of the graph.
Automata groups generated by Cayley machines of groups of nilpotency class two
Authors: Yang Ning
Published: May 2021

We build presentations for automata groups generated by Cayley machines of finite groups of nilpotency class two and prove that these automata groups are all cross-wired lamplighter groups.
MITTAG-LEFFLER STABILITY ANALYSIS OF TEMPERED FRACTIONAL NEURAL NETWORKS WITH SHORT MEMORY AND VARIABLE-ORDER
Authors: GU CHUAN-YUN , ZHENG FENG-XIA , SHIRI BABAK
Published: May 2021

A class of tempered fractional neural networks is proposed in this paper. Stability conditions for tempered fractional neural networks are provided by using Banach fixed point theorem. Attractivity and Mittag-Leffler stability are given. In order to show the efficiency and convenience of the method used, tempered fractional neural networks with and without delay are discussed, respectively. Furthermore, short memory and variable-order tempered fractional neural networks are proposed under the global conditions. Finally, two numerical examples are used to demonstrate the theoretical results.
EXISTENCE OF SOLUTIONS FOR FRACTIONAL EVOLUTION INCLUSION WITH APPLICATION TO MECHANICAL CONTACT PROBLEMS
Authors: CEN JINXIA , LIU YONGJIAN , NGUYEN VAN THIEN , ZENG SHENGDA
Published: May 2021

The goal of this paper is to study an evolution inclusion problem with fractional derivative in the sense of Caputo, and Clarke’s subgradient. Using the temporally semi-discrete method based on the backward Euler difference scheme, we introduce a discrete approximation system of elliptic type corresponding to the fractional evolution inclusion problem. Then, we employ the surjectivity of multivalued pseudomonotone operators and discrete Gronwall’s inequality to prove the existence of solutions and its priori estimates for the discrete approximation system. Furthermore, through a limiting procedure for solutions of the discrete approximation system, an existence theorem for the fractional evolution inclusion problem is established. Finally, as an illustrative application, a complicated quasistatic viscoelastic contact problem with a generalized Kelvin–Voigt constitutive law with fractional relaxation term and friction effect is considered.
MULTIPLE RGB IMAGE ENCRYPTION ALGORITHM WITH MULTILAYERS BY AFFINE HILL CIPHER WITH FRDCT AND ARNOLD TRANSFORM
Authors: GULERIA VANDANA , MISHRA D. C.
Published: May 2021

In this paper, we aim to investigate the security of multiple images based on affine hill cipher (AHC), fractional discrete cosine transform (FrDCT) and Arnold transform (AT). Three original [Formula: see text] images are encoded as a single [Formula: see text] image by first converting three [Formula: see text] images into three indexed images by extracting their color maps. These three indexed image are treated as [Formula: see text], [Formula: see text] and [Formula: see text] channel of a single [Formula: see text] image. Each channel is first encrypted using cryptographic encryption scheme AHC in time domain. The partially encoded image is transformed to frequency domain using FrDCT. In frequency domain, the partially encoded image is scrambled with the help of AT. The proposed scheme assures security in time domain, frequency domain as well as in coordinate domain. The original images can be recovered correctly by using proper arrangements of secret keys. The storage and transmission of the encrypted image is easy due to single encrypted image. The robustness of the proposed approach is proved by conducting computer simulations on standard examples.
NUMERICAL SOLUTION OF NONLINEAR FRACTIONAL DIFFERENTIAL EQUATIONS USING HAAR WAVELET COLLOCATION METHOD
Authors: DESHI A. B. , GUDODAGI G. A.
Published: May 2021

Recently, wavelets are playing a very important role in the numerical analysis. In this paper, an investigation is made for numerical solution of a class of nonlinear fractional differential equations (FDEs) with error analysis using Haar wavelet collocation method. The proposed method is illustrated through presenting different kinds of FDEs, which gives the approximate solution and is in good agreement with the exact solution than the traditional numerical methods. The error will be reduced by increasing the number of collocation points and is justified through the illustrative examples.
FRACTIONAL ORDER VOLTERRA INTEGRO-DIFFERENTIAL EQUATION WITH MITTAG-LEFFLER KERNEL
Authors: KHAN HASIB , ABDELJAWAD THABET , GÓMEZ-AGUILAR J. F. , TAJADODI HALEH , KHAN AZIZ
Published: May 2021

In literature, the integro-differential equations (IDEs) are very much common in the engineering as well in the scientific fields for modeling of dynamical problems. There is a large number of contributions in the study of IDEs for the integer orders. But the cases in fractional order are limited and need consideration of the researchers in the area. In this paper, we initiate a study for fractional Volterra IDEs with Mittag-Leffler kernel for the existence, stability and numerical simulations. For the expression of the results, illustrative work is included.
AN ANALYTICAL MODEL FOR PORE AND TORTUOSITY FRACTAL DIMENSIONS OF POROUS MEDIA
Authors: XU PENG , CHEN ZHENYU , QIU SHUXIA , YANG MO , LIU YANWEI
Published: May 2021

Accurate characterization of pore-scale structures of porous media is necessary for studying their transport mechanisms and properties. An analytical model for pore and capillary structures of porous media is developed based on fractal theory in this study. The pore and tortuosity fractal dimensions are introduced to characterize the pore size distribution and tortuous flow paths. A power law scaling between fractal probability function and pore diameter is proposed, which can be applied to determine the pore fractal dimension. The explicit expression for tortuosity fractal dimension is derived based on exactly self-similar fractal set and fractal capillary bundle model. The present fractal model has been validated by comparison with that of experiments and numerical simulations as well as theoretical models. The results show that the tortuosity fractal dimension decreases as porosity and pore fractal dimension increase, it increases with the increment of tortuosity. Both the particle shape and pore size range take important effect on the tortuosity fractal dimension under certain porosity. The proposed pore-scale model can present a conceptual tool to study the transport mechanisms of porous media and may provide useful guideline for oil and gas exploitation, hydraulic resource development, geotechnical engineering and chemical engineering.
SELF-AFFINE SETS: THE RELATION BETWEEN POSITIVE LEBESGUE MEASURE AND NON-EMPTY INTERIOR
Authors: DENG QI-RONG , LI SI-MIN
Published: May 2021

For the self-affine IFS [Formula: see text] satisfying the weak separation condition (WSC), let [Formula: see text] be the corresponding self-affine set. It is proven in this paper that [Formula: see text] has positive Lebesgue measure only if the interior of [Formula: see text] is non-empty.
FRACTAL EVIDENCE OF REACTIVE TRANSPORT IN POROUS MEDIA UNDER ACID GAS INJECTION
Authors: AMADU MUMUNI , MIADONYE ADANGO
Published: May 2021

In the geologic and soil science literature, the fractal model of porous systems abound. Consequently, any process, be it physicochemical or geomechanical that impacts pore structure will equally impact the fractal nature of the system. Several studies have reported the effect of physicochemical processes such as water–rock interations, on the fractal dimension of the porous system using different approaches involving sophisticated instrumentation. Others have also reported the effect of geomechanical processes such as compaction on fractal dimension using similar approaches. To the best of our knowledge, none or little has been reported regarding the use of multiphase flow hydraulic models for revealing the effect of water–rock interactions on the fractal dimension and pore size distribution of porous systems under acid gas injection. Consequently, to fill the knowledeg gap, data on two-phase flow of acid gas and brine in porous media have been used to show that the fractal dimension and pore size distribution of the porous system change in response to water–rock interactions. The bases of the study are hydraulic models integrating the pore size distribution index parameter that have intimate associations with fractal dimension. Most importantly, the results of this study show that data on two-phase flow in porous media involoving acid gas and brine can be used to show changes in the fractal nature of the porous system, consistent with measurements made using sophisticated methods for core analysis.