bluuebunny/crossref_metadata_2025 huggingface dataset:
Factor-Based Investing in Market Cycles: Fama–French Five-Factor Model of Market Interest Rate and Market Sentiment
Authors: Kuo Yu-Shang , Huang Jen-Tsung
Published: October 2022

This study explores risk–reward patterns in the US stock market and establishes optimal factor-based investing using the Fama–French five-factor model through market cycles constructed by Shiller’s interest rates and Baker–Wurgler’s sentiments. Our emerging evidence confirms that the high-interest rate, high-sentiment cycle generates higher excess returns, and the low-interest rate, low-sentiment cycle generates lower excess returns, which supports the hypothesis that the market cycles as investment horizons have an asymmetric effect on stock returns. Furthermore, the size factor outperforms in the low-interest rate, low-sentiment cycle, whilst the value factor outperforms in the high-interest rate, high-sentiment cycle. Using the asymmetric GARCH model, the asymmetric leverage effect of interest rates and sentiments on five-factor returns is empirically demonstrated with explanatory power of five-factor characteristics. Unlike previous studies, our findings also imply that high- and low-sentiment cycles asymmetrically affect the value factor, and the value premium does not disappear over time, highlighting the role of the market cycles in five-factor returns.
On Financial Distributions Modelling Methods: Application on Regression Models for Time Series
Authors: Dewick Paul R.
Published: October 2022

The financial market is a complex system with chaotic behavior that can lead to wild swings within the financial system. This can drive the system into a variety of interesting phenomenon such as phase transitions, bubbles, and crashes, and so on. Of interest in financial modelling is identifying the distribution and the stylized facts of a particular time series, as the distribution and stylized facts can determine if volatility is present, resulting in financial risk and contagion. Regression modelling has been used within this study as a methodology to identify the goodness-of-fit between the original and generated time series model, which serves as a criterion for model selection. Different time series modelling methods that include the common Box–Jenkins ARIMA, ARMA-GARCH type methods, the Geometric Brownian Motion type models and Tsallis entropy based models when data size permits, can use this methodology in model selection. Determining the time series distribution and stylized facts has utility, as the distribution allows for further modelling opportunities such as bivariate regression and copula modelling, apart from the usual forecasting. Determining the distribution and stylized facts also allows for the identification of the parameters that are used within a Geometric Brownian Motion forecasting model. This study has used the Carbon Emissions Futures price between the dates of 1 May 2012 and 1 May 2022, to highlight this application of regression modelling.
Optimal Landfill Site Selection for Solid Waste of Three Municipalities Based on Boolean and Fuzzy Methods: A Case Study in Kermanshah Province, Iran
Authors: Mousavi Seyed Mohsen , Darvishi Golnaz , Mobarghaee Dinan Naghmeh , Naghibi Seyed Amir
Published: October 2022

In recent decades, population increase and urban development have led to catastrophic environmental consequences. One of the principal objectives to achieve “sustainable development” is to find suitable landfills. Due to their physical characteristics, which have led to a lack of landfill sites and closeness to water bodies, agricultural fields, and residential areas, the cities of Javanrood, Paveh, and Ravansar were chosen as the necessary research regions. On the other hand, these landfills are unable to accommodate the growing urban population. Therefore, this study attempts to develop a framework for spotting the most suitable sites for landfill construction with these three cities as case studies. For this, 10 important driving factors (9 factors and 1 constraint) in landfill site selection were generated. Second, for the fuzzy membership function, the analytic hierarchy process (AHP) method was employed for the standardization of criteria and determining the weight of the driving factors. Then, the Boolean, weighted linear combination (WLC) and ordered weighted average (OWA) methods were utilized to spot optimal sites for landfills. Finally, two suitable sites were found for landfills: site (a) was obtained from the WLC, and site (b) was obtained from OWA-low risk some trade-off (LRST) methods. Our results proved the high efficiency of multi-criteria decision-making methodology for landfill site selection.
(1S,5R)-6,6-Dimethyl-4-(((1S,2S,5S)-2,6,6-trimethyl-4-oxobicyclo[3.1.1]heptan-2-yl)methyl)bicyclo[3.1.1]hept-3-en-2-one
Authors: Ardashov Oleg V. , Korchagina Dina V. , Bagryanskaya Irina Yu. , Volcho Konstantin P. , Salakhutdinov Nariman F.
Published: October 2022

A simple and convenient procedure for the γ, β-dimerization of verbenone was developed. The dimer was obtained during aging with KOH without a solvent. The process proceeds as the formation of the extended enolate of verbenone and its Michael addition to other molecules of verbenone. The product yield was 82% after purification by column chromatography and recrystallization.
Investigation of Fluidity and Strength of Enhanced Foam-Cemented Paste Backfill
Authors: Shi Xiuzhi , Zhao Zhengkai , Chen Xin , Kong Kun , Yuan Jingjing
Published: October 2022

To solve the problems of high cement dosage and poor fluidity of conventional cemented paste backfill (CPB) materials, the fluidity and strength properties of foam-cemented paste backfill (FCPB) were studied in combination. Based on determining the optimum contents of a foaming agent and a foam stabilizer, FCPB density was measured. To investigate the fluidity and strength of FCPB under different foam contents (0%, 5%, 10%, 15%, 20%, 25%, 30%, and 40%), different solid contents (75 wt.% and 77 wt.%), and different cement-tailing ratios (1:4 and 1:5), spread tests and unconfined compressive strength (UCS) tests were conducted. In addition, the FCPB microstructure was analyzed by scanning electron microscopy (SEM). The results indicate that the optimum combination dosages of sodium lauryl sulfate (K12) and sodium carboxymethyl cellulose (CMC) are 0.5 g/L and 0.2 g/L. The density decreases with the foam content (FC), but the fluidity and strength of the FCPB increase first and then decrease with the FC. In addition, the microstructure analysis explains the enhanced strength of FCPB by adding foam. These results contribute to further understanding the effect of foam content on the fluidity and strength of the FCPB.
Hardness Assessment Considering Nitrided Layers Based on Tempering Tests for Numerical Wear Prediction for Forging Processes
Authors: Behrens Bernd-Arno , Brunotte Kai , Wester Hendrik , Lorenz Uwe , Müller Felix
Published: October 2022

The nitriding of forging tools is an industrially established standard used to increase the hardness of the tool surface layer and reduce wear. However, this modification of the tool surface layer, as well as the microstructural changes that occur during this operation due to the thermo-mechanical load, cannot be considered during wear calculations with the widely used Archard wear model in the context of FE simulations. Based on previous work, this study further develops two tempering tests for the investigation of the hardness evolution of two nitride profiles based on H11 tool steel. Here, significant tempering effects could be observed depending on temperature, mechanical stress superposition and time. The results are used for setting up a new material model that is implemented in an existing numerical wear model. The validation is carried out in two laboratory forging test series. The evaluation shows that the hardness development in terms of tempering effects of a nitrided forging tool can be numerically predicted, especially for high forging cycles. However, due to the unexpected occurrence of adhesion effects, only limited applicability of the wear prediction then carried out is achieved.
Study on the Pyrolysis and Adsorption Behavior of Activated Carbon Derived from Waste Polyester Textiles with Different Metal Salts
Authors: Zhou Lun , Zhong Meng-Qi , Wang Teng , Liu Jing-Xin , Mei Meng , Chen Si , Li Jin-Ping
Published: October 2022

In this study, the effects of the catalysis of heavy metals on the pyrolysis of waste polyester textiles (WPTs) and the adsorption behaviors of the pyrolysis products of WPTs for Cr(VI) were explored. TG−DTG analysis indicated that the metal ions catalyzed the pyrolysis process by reducing the temperature of the decomposition of WPTs. The surface morphology and pore structure of the carbons were analyzed using SEM and BET. The results demonstrated that Zn−AC possessed the largest specific surface area of 847.87 m2/g. The abundant acidic functional groups on the surface of the activated carbons were proved to be involved in the Cr(VI) adsorption process via FTIR analysis. Cr(VI) adsorption experiments indicated that the adsorption process was more favorable at low pH conditions, and the maximum adsorption capacities of Zn−AC, Fe−AC, and Cu−AC for Cr(VI) were 199.07, 136.25, and 84.47 mg/g, respectively. The FTIR and XPS analyses of the carbons after Cr(VI) adsorption, combined with the adsorption kinetics and isotherm simulations, demonstrated that the adsorption mechanism includes pore filling, an electrostatic effect, a reduction reaction, and complexation. This study showed that metal salts catalyze the pyrolysis processes of WPTs, and the activated carbons derived from waste polyester textiles are promising adsorbents for Cr(VI) removal.
Optimization of Thermo-Mechanical Fatigue Life for Eutectic Al–Si Alloy by the Ultrasonic Melt Treatment
Authors: Wang Meng , Pang Jianchao , Liu Xinfeng , Wang Jianqiu , Liu Yongquan , Li Shouxin , Zhang Zhefeng
Published: October 2022

The eutectic cast Al–Si alloys with excellent high-temperature and casting performance are widely used in engine pistons. During frequent starts and stops, the thermo-mechanical fatigue (TMF) is the most important failure cause. Ultrasonic melt treatment (UT) was chosen to compare and investigate the influence of micro-structures on fatigue life and damage mechanisms of as-cast (AC) eutectic Al–Si alloys under TMF loading. After UT, the grain size, primary Si, and intermetallic particles are reduced significantly in the alloy; fatigue life increases obviously. As a result of pilling-up of dislocations, the competitive effects of the critical strain/stress for fatigue crack nucleation can be found. There are two different crack initiation mechanisms under TMF: one is primary Si fracture for AC alloys with limited critical strain/stress for fatigue crack nucleation at fractured Si particles, and the other is primary Si debonding for UT alloys with increasing critical fracture strain/stress. After the crack initiation, the fractured or debonded primary phases provide the advantages for the further development of main cracks for both alloys. The UT alloy (805 ± 253 cycles) has about twice the TMF life of the AC alloy (403 ± 98 cycles). The refinement of micro-structures is instrumental in improving the fatigue resistance and life of TMF for the UT alloy.
Enhancement of Physical Properties and Corrosion Resistance of Al-Cu-Al2O3/Graphene Nanocomposites by Powder Metallurgy Technique
Authors: El-Kady Omayma A. , Yehia Hossam M. , Nouh Fathei , Ghayad Ibrahim M. , El-Bitar Taher , Daoush Walid M.
Published: October 2022

In this study, we enhanced the adhesion of graphene nanosheets to achieve homogeneous dispersion, consequently improving the electrical and thermal conductivity, coefficient of thermal expansion, and corrosion resistance with an aluminum matrix containing up to 1.5 wt. % graphene. First, 2.5 wt. % Al2O3 and varying ratios of graphene up to 1.5 wt. % were coated with 5 wt. % silver nanoparticles to metalize their surfaces. Predetermined portions of coated alumina and graphene were mixed with Al/10 wt. % Cu powder for 45 h. Mixed samples were compacted under 600 MPa and sintered at 565 °C in a vacuum furnace for 60 min with a low heating rate of 2 °C/min. The strengthening effect of the added materials on the density, microstructure, electrical and thermal conductivities, thermal expansion, and corrosion behavior of aluminum were investigated. Excellent adhesion and homogeneous dispersion of the investigated reinforcements were achieved. Three phenomena were observed: (1) an improvement in the densification, electrical and thermal conductivity, thermal expansion, and corrosion rate by adding 10 wt. % Cu to the aluminum matrix; (2) deterioration of the properties of Al/10 wt. % Cu with the addition of 2.5 wt. % alumina nanoparticles; and (3) improved properties with the addition of graphene nanosheets up to 1 wt. % and a decrease in property values beyond 1.5 wt. % graphene content due to the formation of agglomerations and pores in the metal matrix.
Susceptibility to Pitting and Environmentally Assisted Cracking of 17-4PH Martensitic Stainless Steel Produced by Laser Beam Melting
Authors: Guennouni Nizar , Maisonnette Daniel , Grosjean Christophe , Poquillon Dominique , Blanc Christine
Published: October 2022

Materials produced by additive manufacturing (AM) often have different microstructures from those obtained using conventional metallurgy (CM), which can have significant impacts on the materials’ durability, and in particular, resistance to corrosion. In this study, we were concerned with the susceptibility to pitting and environmentally assisted cracking (EAC) of 17-4PH martensitic stainless steel (MSS). We focused on the evolution from pitting to EAC, and the behaviour of MSS produced by AM was compared with that of its CM counterpart. Potentiodynamic polarisation tests were combined with chronoamperometry measurements performed without and with mechanical loading to study both stable and metastable pitting and the influence of stress on these processes. EAC tests were carried out and combined with observations of fracture surfaces. MSS produced by AM was more resistant to pit initiation due to fewer and finer NbC particles. However, the propagation kinetics of stable pits were higher for this MSS due to a higher amount of reversed austenite. The stress was found to stabilise the metastable pits and to accelerate the propagation of stable pits, which resulted in an increased susceptibility to EAC of the MSS produced by AM. These results clearly highlighted the fact that the reversed austenite amount has to be perfectly controlled in AM processes.
Elastocaloric Properties of Polycrystalline Samples of NiMnGaCu Ferromagnetic Shape Memory Alloy under Compression: Effect of Improvement of Thermoelastic Martensitic Transformation
Authors: Villa Francesca , Bestetti Emanuele , Frigerio Roberto , Caimi Michele , Tomasi Corrado , Passaretti Francesca , Villa Elena
Published: October 2022

Shape memory alloys (SMAs) and ferromagnetic shape memory alloys (FeSMAs) have recently attracted interest for solid state refrigeration applications. Among NiMnGa-based quaternary systems, NiMnGaCu exhibits an interesting giant magnetocaloric effect thanks to the overlapping of the temperatures related to the magnetic transition and the thermoelastic martensitic transformation (TMT); in particular, for compositions with Cu content of approximately 6 at%. In the present work, we investigated the improvement effect of TMT on the total entropy change (ΔS) in the elastocaloric performances of polycrystalline Ni50Mn18.5Cu6.5Ga25 at% alloy samples, just above room temperature. We report an extensive calorimetric and thermomechanical characterization to explore correlations between microstructural properties induced by the selected thermal treatment and elastocaloric response, aiming at providing the basis to develop more efficient materials based on this quaternary system. Both ΔT and ΔS values obtained from mechanical curves at different temperatures and strain recovery tests under fixed load vs. T were considered. Maximum values of ΔS = 55.9 J/KgK and ΔT = 4.5 K were attained with, respectively, a stress of 65 MPa and strain of 4%. The evaluation of the coefficient of performance (COP) was carried out from a cyclic test.
Inhibition Effect of Hydrophobic Functional Organic Corrosion Inhibitor in Reinforced Concrete
Authors: Huang Jinzhen , Hu Jie , Cai Jinshun , Huang Haoliang , Wei Jiangxiong , Yu Qijun
Published: October 2022

Using an admixed organic corrosion inhibitor is one of the most efficient strategies to enhance the corrosion resistance and durability of reinforced concrete. However, traditional admixed organic corrosion inhibitors only increase the corrosion resistance of the embedded reinforcing steel, and the optimization effect on the pore structure and the impermeability of concrete is very limited. In this study, in order to evaluate the corrosion-inhibition effect of a novel hydrophobic functional organic corrosion inhibitor, the adsorption behavior of a hydrophobic functional organic corrosion inhibitor and its related effect on the electrochemical behavior of the reinforcing steel was investigated. In addition, this paper further discusses the effect of a hydrophobic functional organic corrosion inhibitor on pore structure and hydrophobic properties, as well as the impermeability of concrete. The results indicated that the hydrophobic functional organic corrosion inhibitor was effectively adsorbed on the surface of the steel bar, and the higher adsorption content was relevant to the higher inhibitor dosage. On one hand, the hydrophobic functional organic corrosion inhibitor exhibited both a pore-blocking effect and a hydrophobic effect on concrete, leading to a refined pore structure and reduced capillary water absorption amount; on the other hand, the hydrophobic functional organic corrosion inhibitor exhibited an excellent corrosion-inhibition effect on the reinforcement embedded in the concrete, presenting an inhibition efficiency higher than 90% with a concentration of 4 wt.%.
Fast Absorbent and Highly Bioorthogonal Hydrogels Developed by IEDDA Click Reaction for Drug Delivery Application
Authors: Joo Soo-Bin , Gulfam Muhammad , Jo Sung-Han , Jo Yi-Jun , Vu Trung Thang , Park Sang-Hyug , Gal Yeong-Soon , Lim Kwon Taek
Published: October 2022

In this work, we engineered highly biocompatible and fast absorbent injectable hydrogels derived from norbornene (Nb)-functionalized hyaluronic acid (HA-Nb) and a water-soluble cross-linker possessing tetrazine (Tz) functional groups on both ends of polyethylene glycol (PEG-DTz). The by-product (nitrogen gas) of the inverse electron demand Diels–Alder (IEDDA) cross-linking reaction carved porosity in the resulting hydrogels. By varying the molar ratio of HA-Nb and PEG-DTz (Nb:Tz = 10:10, 10:5, 10:2.5), we were able to formulate hydrogels with tunable porosity, gelation time, mechanical strength, and swelling ratios. The hydrogels formed quickly (gelation time < 100 s), offering a possibility to use them as an injectable drug delivery system. The experimental data showed rapid swelling and a high swelling ratio thanks to the existence of PEG chains and highly porous architectures of the hydrogels. The hydrogels were able to encapsulate a high amount of curcumin (~99%) and released the encapsulated curcumin in a temporal pattern. The PEG-DTz cross-linker, HA-Nb, and the resulting hydrogels showed no cytotoxicity in HEK-293 cells. These fast absorbent hydrogels with excellent biocompatibility fabricated from HA-Nb and the IEDDA click-able cross-linker could be promising drug carriers for injectable drug delivery applications.
Tensile Strain Capacity Prediction Model of an X80 Pipeline with Improper Transitioning and Undermatched Girth Weld
Authors: Chen Hongyuan , Dai Lianshuang , Xuan Heng , Gao Xiongxiong , Yang Kun , Wang Lei , Chi Qiang , Huo Chunyong
Published: October 2022

As an important component of strain-based design, the tensile strain capacity (TSC) concept has been extensively used for pipelines that experience expectable plastic strain for both installation and service. However, some stress-based designed pipelines have experienced unforeseen plastic strain in the past decade that resulted in failure. It seems that the tensile strain capacity has gradually become an important requirement for geohazard risk management and pipeline maintenance of stress-based design pipelines. The tensile strain capacity of an X80 pipeline is investigated. The assessment in this work was based on the fracture initiation–control-based limit state. This limit state corresponds to the onset of stable tearing and generally provides a reasonably conservative estimate. Besides that, factors such as wall thickness, material’s strain hardening capacity, toughness, weld strength mismatch, HAZ (heat-affected zone) softening, pipe wall thickness, high–low misalignment, and internal pressure were also investigated to construct a prediction model of the X80 vintage pipeline.
On the Residual Stresses and Fracture Toughness of Glass/Carbon Epoxy Composites
Authors: Umarfarooq M. , Gouda P. , Banapurmath N. , Kittur M. , Khan Tabrej , Badruddin Irfan , Kamangar Sarfaraz , Hussien Mohamed
Published: October 2022

The resistance to delamination in polymer composite depends on their constituents, manufacturing process, environmental factors, specimen geometry, and loading conditions. The manufacturing of laminated composites is usually carried out at an elevated temperature, which induces thermal stresses in composites mainly due to a mismatch in the coefficient of thermal expansion (CTE) of fiber and matrix. This work aims to investigate the effect of these process-induced stresses on mode-I interlaminar fracture toughness (GI) of Glass-Carbon-Epoxy (GCE) and Glass-Epoxy (GE) composites. These composites are prepared using a manual layup technique and cured under room temperature, followed by post-curing using different curing conditions. Double cantilever beam (DCB) specimens were used to determine GI experimentally. The slitting technique was used to estimate residual stresses (longitudinal and transverse direction of crack growth) inherited in cured composites and the impact of these stresses on GI was investigated. Delaminated surfaces of composites were examined using a scanning electron microscopy (SEM) to investigate the effect of post-curing on the mode-I failure mechanism. It was found that GI of both GE and GEC composites are sensitive to the state of residual stress in the laminas. The increase in the GI of laminates can also be attributed to an increase in matrix deformation and fiber–matrix interfacial bond with the increase in post-curing temperature.
Anti-Soiling Coatings for Enhancement of PV Panel Performance in Desert Environment: A Critical Review and Market Overview
Authors: Hossain Mohammad Istiaque , Ali Adnan , Bermudez Benito Veronica , Figgis Benjamin , Aïssa Brahim
Published: October 2022

Areas with abundant sunlight, such as the Middle East and North Africa (MENA), are optimal for photovoltaic (PV) power generation. However, the average power loss of photovoltaic modules caused by dust accumulation is extreme and may reach 1%/day, necessitating frequent cleaning which adds to the cost of operations and maintenance. One of the solutions to the problem of PV soiling is to develop anti-soil coatings, where hydrophilic or hydrophobic coatings with spectral characteristics suitable for PV applications are added to the outer layer of PV glass. However, the effectiveness of such coatings depends extensively on climatic conditions and geographical locations. Since coatings add to the cost of solar panels, it is imperative that they are first tested for suitability at the intended location and/or in similar weather conditions prior to their large-scale deployment. This critical review focuses on various anti-dust technologies employed to mitigate the PV soiling issue. The in-depth comparison of the various developed techniques and materials aims at providing a relevant input in adapting the right technology based on particles’ accumulation mechanism, weather conditions, and geographical location. Though the mechanical cleaning process is the most used solution to date, development of thin film anti-dust coating could be a better alternative—when it is relevant—due to its abrasion-free capability, large deployment, economic viability, and durability. This review aims at serving as a reference in this topic, thereby paving the way to adapting efficient anti-dust coatings, especially in the MENA region and/or desert environment at large, where it is the most relevant.
Analytical and Experimental Study on Cold-Formed Steel Built-Up Sections for Bending
Authors: Sujitha R. , Sunmathi N. , Manikandan R. K. , Arunprasad J. , Rajkumar S. , Sharma Shubham , Sharma Kamal , Li Changhe , Tag Eldin Elsayed Mohamed
Published: October 2022

In the construction of steel structures, the two most common types of structural members are hot-formed and cold-formed members. This paper mainly describes the analytical and experimental research on the strength and characteristics of CFS bolted built-up sigma sections having different structural arrangements under bending. The cross-sectional dimensions for the parametric study were selected by the sizes available in the market. In this paper, ANSYS workbench software was used to perform FE modeling and observe the local, flexural, and interaction of these buckling. Then, experimental study was performed by varying the arrangement of open section beams between face-to-face and back-to-back, connected using bolts or fasteners different spacings. Further, we conducted bending tests on cold-formed steel built-up members having simple edge stiffeners in the middle. Comparing both analytical and experimental studies, the results indicate that the back-to-back connected built-up beam section provides a flexural capacity higher than the face-to-face built-up section. Moreover, increasing the bolt spacing enhanced the load-carrying capacity of back-to-back sigma section built-up beams. It has also been discovered that the flexural strength of beams is primarily determined by bolt spacing or itsposition.
Experimental Investigation of Effect of Flake Silver Powder Content on Sintering Structure and Properties of Front Silver Paste of Silicon Solar Cell
Authors: Li Wei , Yu Chunxiu , Wang Yunkai , Yao Yuan , Yu Xianglei , Zuo Chuan , Yu Yang
Published: October 2022

Optimizing the performance of front silver paste is of great significance in improving the efficiency of the photoelectric conversion of crystalline silicon solar cells. As a conductive functional phase of silver paste, the structure and performance of silver powder have an important influence on the sintering process of silver paste and the conductivity of silver electrodes. Because of their two−dimensional structure, flake silver powders can effectively increase the contact area with other silver powders and silicon cells before sintering. Additionally, flake silver particles have higher surface energy and sintering activity than spherical silver particles of the same particle size. However, recent research has mainly focused on the influence of the particle size of silver powder. This paper fills the research gap regarding the morphology of silver powders and clarifies the influence of flake silver powders on the performance of silver paste. The influence of the ratio of spherical silver powder to flake silver powder in silver paste on the sheet resistance, adhesion, and specific contact resistivity of silver film after sintering at 800 °C was studied, and the optimal ratio was determined according to a cross−sectional contact picture of the silver film. The results showed that with the increase in the mass fraction of the flake silver powder, the sheet resistance of the sintered silver film gradually increased, the adhesion first increased and then decreased, and the specific contact resistance first decreased and then increased. When the flake silver powder content was 0%, the minimum sheet resistance of the silver film was 2.41 m Ω/☐. When the flake silver powder content was 30%, the maximum adhesion of the silver film was 6.07 N. When the flake silver powder content was 50%, the minimum specific contact resistivity of the silver film was 0.25 Ω·cm2. In conclusion, when the flake silver powder content was 30%, the comprehensive performance of the silver film was the best.
The Characteristic and Distribution of Shale Micro-Brittleness Based on Nanoindentation
Authors: Yang Liu , Mao Yuting , Yang Duo , Han Zhenchuan , Li Sheng , Cai Jianchao , He Manchao
Published: October 2022

Shale is a special kind of rock mass and it is particularly important to evaluate its brittleness for the extraction of gas and oil from nanoporous shale. The current brittleness studies are mostly macro-evaluation methods, and there is a lack of a micro-brittleness index that is based on nanoindentation tests. In this paper, nanoindentation tests are carried out on the surface of shale to obtain mechanical property, and then a novel micro-brittleness index is proposed. Drawing a heat map by meshing indentation, the distribution characteristics of the brittleness index for the surface of shale and the variation laws between the mineral and brittleness index are explored. The results showed that the dimensionless brittleness index involved parameters including indentation irreversible deformation, elastic modulus, hardness and fracture toughness. The micro-brittleness index of the shale ranged from 7.46 to 65.69, and the average brittleness index was 25.837. The brittleness index exhibited an obvious bimodal distribution and there was great heterogeneity on the surface of shale. The crack propagation channels were formed by connecting many indentation points on the shale surface with high brittleness. The total brittleness index of quartz minerals was high, but the cementation effect with different minerals was various. Although the general brittleness of clay was low, the high brittleness index phenomenon was also exhibited. Studying the micro-brittleness of shale provides a more detailed evaluation for the shale friability, which is used to determine the optimal shale oil and gas recovery regime.
Tribological Properties Study of Solid Lubrication with TiO2 Powder Particles
Authors: Ilie Filip , Ipate George , Manaila Florentina Cristina
Published: October 2022

Titanium dioxide (TiO2), by its tribological behavior, is known as a solid lubricant. TiO2 as a solid lubricant, together with tungsten disulfide (WS2) and molybdenum disulfide (MoS2) decreases friction and excessive wear. By compacting TiO2 powder, pellets are formed. Studies and research on the solid lubricant coatings were conducted with success on a tribometer with the possibility of making two simultaneous contacts, pellet/disk, and slider pad/disk. On the disk of a tribometer, we studied the lubrication characteristics of the TiO2 powder particles as the third body by intentionally transferring. Results show that the TiO2 pellet behaved like an effective oil-free lubricant by self-repairing and self-replenishing. In experiments, a TiO2 pellet is intentionally sheared against the surface of the disk, while the slider pad slips loaded on the lubricated surface until the deposited powder film is exhausted. A theoretical model control volume fractional coverage (CVFC) was used to estimate both the wear rate for the lubricated pellet/disk sliding contact and the friction coefficient at the pad/disk separation surface. According to materials properties, disk velocity, pellet and slider pad load, the pellet wear rate, and slider pad friction coefficient, using the CVFC model, can establish the pellet wear rate, and slider pad friction coefficient. The fractional coverage represents a parameter of the CVFC model that varies with time, and it is useful for estimating the film amount from the third body that covers the disk asperities. Model results well enough describe the tribological behavior of the sliding contacts in experiments, both qualitatively and quantitatively. In addition, the theoretical results obtained by modeling and the experimental those obtained in the process of friction, are compared.
Simulation of Four-Point Bending Fracture Test of Steel-Fiber-Reinforced Concrete
Authors: Kan Wenguang , Yang Zailin , Yin Weilong
Published: October 2022

To investigate the influence of addition amount and length of steel fibers on the bearing capacity of a concrete beam, this study simulated the crack propagation process of a concrete beam in a four-point bending experiment. The extended finite element method (XFEM) using the ABAQUS software was adopted. Additionally, stress distribution trends for the concrete under loading and load–displacement curves at the stressed points were obtained. The simulation results for a concrete beam with different amounts and lengths of steel fibers were compared and analyzed, and conclusions were drawn. The experiment shows that the flexural performance of the concrete improves with increases in the length and amount of steel fibers, but the reinforcement effects produced by different amounts and lengths of steel fibers are different. When the steel fiber content is 1.5% and the length is 20–25 mm, the reinforcement effect in the concrete is significantly improved, and its flexural strength is nearly doubled.
Dynamic Simulation of Cracked Spiral Bevel Gear Pair Considering Assembly Errors
Authors: Han Hongzheng , Ma Hui , Wang Haixu , Zhu Jiazan , Li Zhanwei , Liu Zimeng
Published: October 2022

The tooth root crack fault is a common fault type of the spiral bevel gear pair (SBGP). Affected by the strong bearing capacity, the early crack fault of the SBGP cannot be found in time. In this study, a finite element (FE) model of the SBGP is established and assembled through the tooth contact analysis. The maximum tooth root stress is analyzed considering the variation of assembly errors. Meanwhile, this study simulates the tooth root crack fault of the bevel pinion with different crack degrees. The initial position of the crack is located where the maximum tooth root stress appears. The time-varying mesh stiffness (TVMS) of the SBGP considering different degrees of the pinion tooth root crack fault is obtained. The TVMS and the non-load transmission error are brought into a hybrid FE dynamic model, and steady responses are solved. Based on this, the sensitivities of various statistical indicators for identifying the tooth root crack fault of SBGP under the influence of assembly errors are verified. This paper can provide the necessary theoretical basis for the analysis and diagnosis of tooth root crack faults in the SBGP transmission system.
Optimal Location and Sizing of PV Generation Units in Electrical Networks to Reduce the Total Annual Operating Costs: An Application of the Crow Search Algorithm
Authors: Cortés-Caicedo Brandon , Grisales-Noreña Luis Fernando , Montoya Oscar Danilo , Perea-Moreno Miguel-Angel , Perea-Moreno Alberto-Jesus
Published: October 2022

This study presents a master–slave methodology to solve the problem of optimally locating and sizing photovoltaic (PV) generation units in electrical networks. This problem is represented by means of a Mixed-Integer Nonlinear Programming (MINLP) model, whose objective function is to reduce the total annual operating costs of a network for a 20-year planning period. Such costs include (i) the costs of purchasing energy at the conventional generators (the main supply node in this particular case), (ii) the investment in the PV generation units, and (iii) their corresponding operation and maintenance costs. In the proposed master–slave method, the master stage uses the Discrete–Continuous version of the Crow Search Algorithm (DCCSA) to define the set of nodes where the PV generation units will be installed (location), as well as their nominal power (sizing), and the slave stage employs the successive approximation power flow technique to find the value of the objective function of each individual provided by the master stage. The numerical results obtained in the 33- and 69-node test systems demonstrated its applicability, efficiency, and robustness when compared to other methods reported in the specialized literature, such as the vortex search algorithm, the generalized normal distribution optimizer, and the particle swarm optimization algorithm. All simulations were performed in MATLAB using our own scripts.
A New Point Process Regression Extreme Model Using a Dirichlet Process Mixture of Weibull Distribution
Authors: Wang Yingjie , Liu Xinsheng
Published: October 2022

The extreme value theory is widely used in economic and environmental domains, it aims to study the stochastic extreme behaviors associated with rare events. In this context, we consider a new mixture model for extremal events analysis, including a Dirichlet process mixture of Weibull (DPMW) distribution below the threshold and the point process (PP) extreme model for the upper tail. This model developed a regression structure for the PP extreme model parameters, which explains the variation of the exceedance through all tail parameters. The estimation of the model parameters is performed under the Bayesian paradigm, applying the Markov chains Monte Carlo (MCMC) method. The model is applied to both simulation and real environmental data to demonstrate the performance in extrapolating extreme events.
The Inlay Technique with Cortico-Cancellous Olecranon Bone Graft Used for Revision of Failed Distal Interphalangeal Joint Arthrodesis
Authors: Ko Sang-Hyun , Park Joo-Won , Lee Tong-Joo
Published: October 2022

Background and Objectives: Although distal interphalangeal (DIP) arthrodesis is an effective surgical method for end-stage osteoarthritis of the phalangeal joint, the nonunion rate of DIP arthrodesis has been reported to range from 15% to 20%. To this end, we devised an inlay technique with a cortico-cancellous olecranon bone graft for failed DIP arthrodesis. This study aimed to introduce the inlay bone grafting technique for failed arthrodesis of the DIP joint and demonstrate its advantages. Materials and Methods: We reviewed consecutive 19 digits (15 patients) who had undergone DIP revision arthrodesis using the technique at our institution between January 2010 and December 2020. The observed outcome measures were the bone union rate, and related complications. Bone union was evaluated using follow-up radiography. The quick Disabilities of the Arm, Shoulder and Hand (DASH), visual analog scale (VAS) for pain, and VAS for satisfaction assessed patient function and perceived clinical outcomes. Results: No major complications were observed at the recipient site. The average VAS for pain and satisfaction and DASH score improved from preoperatively to 6 months after surgery (both, p = 0.001). Conclusions: The inlay technique with cortico-cancellous olecranon bone grafts showed excellent bone union rates and functional scores with nonunion of the DIP joint. This technique may be an adequate surgical option for patients with confirmed nonunion of the DIP joint and persistent symptoms.
Polypharmacy in Older Adults with Alzheimer’s Disease
Authors: Esumi Satoru , Ushio Soichiro , Zamami Yoshito
Published: October 2022

The number of patients with Alzheimer’s disease is increasing annually. Most of these patients are older adults with comorbid physical illnesses, which means that they are often treated with a combination of medications for the disease they have and those for Alzheimer’s disease. Thus, older adults with Alzheimer’s disease are potentially at risk for polypharmacy. In addition, the drug interactions between Alzheimer’s disease medications and those for the treatment of physical illnesses may reduce their efficacy and increase side effects. This article reviews polypharmacy and drug interactions in elderly patients with Alzheimer’s disease, with a focus on psychotropic drugs.
Inflammatory Disorders of the Central Nervous System Vessels: Narrative Review
Authors: Ekkert Aleksandra , Šaulytė Marta , Jatužis Dalius
Published: October 2022

Inflammatory disorders of the central nervous system (CNS) vessels, also called CNS vasculitides, can cause substantial disability or even be fatal. Inflammation of the CNS vessels can be caused by primary angiitis of the CNS (PACNS), inflammatory cerebral amyloid angiopathy, or systemic inflammatory disorders. Clinical symptoms of these disorders are often non-specific, such as encephalopathy, cognitive and affective abnormalities, headache and focal neurological symptoms. Diagnostic workup includes a thorough neuropsychiatric examination, blood and cerebrospinal fluid analysis and magnetic resonance imaging (MRI) of the brain and its vessels. Biopsy of the brain remains the gold standard diagnostic test. Timely diagnosis and treatment initiation is of high importance, as it might prevent severe complications, such as ischemic and hemorrhagic stroke. In this review, we describe the specific characteristics of primary and secondary non-infectious CNS vasculitides which help to establish the diagnosis, discuss the peculiarities of the diagnostic workup and present current treatment recommendations.
Neonatal Healthcare-Associated Conjunctivitis: A Descriptive Study from Saudi Arabia
Authors: Alhazmi Abdulaziz , Abuallut Ismail , Alwadani Ismail , Haddad Moayad , Ageeli Bander , Majrabi Hamad , Muslihi Ibrahim , AlAli Laila , Homadi Hana , Madkhli Elaf , Shami Jaber
Published: October 2022

Healthcare-associated conjunctivitis (HAC) has been associated with serious ophthalmological complications in neonates, including blindness. This three-year retrospective, descriptive study was conducted between 2019 and 2021 to determine the most common bacteria associated with neonatal HAC at a tertiary-care hospital in Saudi Arabia. The inclusion criteria were defined based on the centers for disease control and prevention (CDC) guidelines for the diagnosis of neonatal HAC. When HAC was clinically suspected, conjunctival swabs were obtained from neonates and sent to the microbiology lab following standard protocols. A univariate analysis was conducted on the included samples. A total of 79 cases met our inclusion criteria and were retrospectively studied. A descriptive analysis showed that Pseudomonas aeruginosa was the leading cause of HAC, with 25% (20 cases), followed by Escherichia coli and Klebsiella pneumonia (11.5% for each). About 9% of the analyzed cases were positive for Staphylococcus aureus. Orogastric feeding was the most commonly (94%) associated factor with HAC, followed by respiratory distress syndrome (RDS) and preterm birth, which were found in 70% and 64% of the cases, respectively. To conclude, HAC is an alarming healthcare problem, and bacteria, including Gram-negative bacteria, are common causes. Thus, physician awareness, effective communication with microbiologists, and the implementation of infection control recommendations, including hand hygiene, could minimize this problem and avoid the serious complications of HAC.
Scientific Research Directions on the Histopathology and Immunohistochemistry of the Cutaneous Squamous Cell Carcinoma: A Scientometric Study
Authors: Cocuz Iuliu Gabriel , Cocuz Maria Elena , Repanovici Angela , Sabău Adrian-Horațiu , Niculescu Raluca , Tinca Andreea-Cătălina , Vunvulea Vlad , Budin Corina Eugenia , Szoke Andreea Raluca , Popelea Maria Cătălina , Moraru Raluca , Cotoi Titiana Cornelia , Cotoi Ovidiu Simion
Published: October 2022

Introduction: Cutaneous squamous cell carcinoma (cSCC) is one of the most frequently occurring types of cancer in humans. Scientometric research is an innovative method for analyzing the research trends in various domains, with great implications in the field of medicine. Materials and Methods: We searched the Web of Science database with the following established query terms: “Squamous cell carcinoma”, “skin”, and “immunohistochemistry”. After applying the inclusion and exclusion criteria, a total of 76 articles were selected. The present study aims to analyze, based on the frequency of use of keywords with scientometric algorithms and map-based distributions, the trends of the research concerning cSCCs in 2017–2022. Results: A graphical representation based on 11 scientometric maps presented the division of the keywords into seven clusters, from which seven categories of research interest were defined. The clusters represent a multidisciplinary approach to the diagnosis and treatment of cSCCs, cancer diagnostics, patient outcomes, histopathological importance, management of cSCCs, role of progression, and adequate treatment of and importance of immunohistochemistry for cSCCs. The distribution of the citations shows the importance of the available research on cSCCs by analyzing the first five most-cited articles included in our study in direct concordance with the seven defined clusters. Conclusion: The scientometric research method reveals the interest of research in the multidisciplinary approach used to obtain the best outcomes for the patient, including a targeted investigation, as well as diagnostic and treatment options. The trends in the research reveal that histopathological diagnostics and immunohistochemistry, combined with molecular techniques, are the most important tools used to establish a personalized diagnosis, thus increasing the quality of life and life expectancy for patients with cSCCs.
A Substructure Condensed Approach for Kinetostatic Modeling of Compliant Mechanisms with Complex Topology
Authors: Wu Shilei , Shao Zhongxi , Fu Hongya
Published: October 2022

Compliant mechanisms with complex topology have previously been employed in various precision devices due to the superiorities of high precision and compact size. In this paper, a substructure condensed approach for kinetostatic analysis of complex compliant mechanisms is proposed to provide concise solutions. In detail, the explicit relationships between the theoretical stiffness matrix, element stiffness matrix, and element transfer matrix for the common flexible beam element are first derived based on the energy conservation law. The transfer matrices for three types of serial–parallel substructures are then developed by combining the equilibrium equations of nodal forces with the transfer matrix approach, so that each branch chain can be condensed into an equivalent beam element. Based on the derived three types of transfer matrices, a kinetostatic model describing only the force-displacement relationship of the input/output nodes is established. Finally, two typical precision positioning platforms with complex topology are employed to demonstrate the conciseness and efficiency of this modeling approach. The superiority of this modeling approach is that the input/output stiffness, coupling stiffness, and input/output displacement relations of compliant mechanisms with multiple actuation forces and complex substructures can be simultaneously obtained in concise and explicit matrix forms, which is distinct from the traditional compliance matrix approach.