Cyclic Mode Research Articles

Heterogeneous-structured Ti-6Al-4V with enhanced mechanical properties in monotonic and cyclic deformation modes

This study aimed to develop heterogeneous-structured (HS) Ti-6Al-4V composed of coarse and fine grains to enhance the alloy's mechanical properties. This microstructure was induced by selective activation of dynamic globularization by using water-quenching and subsequent rolling below the β-transus temperature. Microstructures and mechanical properties of the HS alloy in monotonic and cyclic deformation modes were compared with those of coarse-grained (CG) and ultrafine-grained (UFG) counterparts. HS Ti-6Al-4V had a higher mechanical strength and better resistance to low-cycle fatigue (LCF) fracture without the loss of ductility compared with commercial mill-annealed CG alloy, and HS alloy had an engineering advantage of low-cost mass production in contrast to UFG counterpart, despite their similar mechanical properties under both monotonic and cyclic deformations. The enhanced mechanical properties of HS alloy were attributed to the presence of UFG region and the partial transformation of transverse to basal texture with a high intensity. Such conditions gave rise to an active slip transfer, low internal stress, and high strain compatibility, thereby leading to the high LCF resistance.

A rapid in vitro electrochemical screening of extracellular matrix of Saccharomyces cerevisiae by palladium nanoparticles-modified electrodes

Herein, a rapid electrochemical screening of yeasts (Saccharomyces cerevisiae) in vitro mode depending on their optical density, cultivation time and growth medium used was conducted in 3 min by palladium nanoparticles (Pd-NPs)-modified electrodes. Pd-NPs-modified electrodes operated in cyclic voltammetry mode at low scan rates, i.e. 5–20 mV/s supported a low oxidative process in the yeast extracellular matrix. The electrochemical screening relied on an efficient electrooxidation of secondary metabolites, i.e. organohydrazines formed in the extracellular medium as a result of microbial activity of yeast cells.More importantly, during the study the impact of fundamental parameters, viz. type of the matrix and pH on electroanalytical response of Pd-NPs-based electrodes in real fermentation medium was investigated in detail. The efficiency of the proposed in vitro electrochemical screening of yeast extracellular matrix was not affected by pH of the samples or composition of the multicomponent medium, but more likely exclusively depended on the presence of organohydrazines. The potential of this electroanalytical approach towards profiling of the extracellular matrix of Saccharomyces cerevisiae was compared with results obtained by gas chromatography mass-spectrometry (GC–MS) and genetically encoded biosensor (ro-GFP2) assays.

Oil Palm Fibers Micromechanics: Anisotropic Behavior

ABSTRACT The anisotropic behavior of oil palm fibers (OPF) was investigated using finite element models, which were used to fit experimental data from stalk and mesocarp oil palm fibers under different tensile deformation modes. The experimental results showed damage to oil palm fibers due to deformation, viscoelastic behavior from reduced stress at fixed strain, as well as anisotropic behavior from tensile-twisting tests. In this work, the finite element models were improved from the previous works on the fiber mechanics by including Fung orthotropic and Prony series viscoelastic functions. The developed single-element finite element model agreed with experimental tensile data under cyclic, stress-relaxation, and step-relaxation modes. The modeling parameters from the single element model and information from the experimental work were then used to simulate the deformation of a virtual fiber obtained from µ-CT analysis, as well as its composite model.

Enhancing Methane Recovery with Cryogenic Liquid CO2 Cyclic Injection: Determination of Cyclic Injection Parameters.

Carbon dioxide (CO2) is both a primary greenhouse gas and a readily available energy source. In this study, a new underground coal permeability enhancement technique utilizing cryogenic liquid CO2 (L-CO2) cyclic injection is proposed. The key parameters that determine the feasibility of this technique are cycle period and cycle number within a fixed working period. The optimal value of these two parameters mainly depends on the pore structure evolution law of coal cores before and after cryogenic L-CO2 cyclic freeze–thaw. Accordingly, nuclear magnetic resonance (NMR) was employed to study the evolution characteristics of the fracture networks and pore structures in coal cores subjected to different freeze–thaw cyclic modes. The results demonstrated that the amplitude and width of all peaks of the T2 spectra of the three coal cores (lignite, gas coal, and 1/3 coking coal) increased with an increase in the number of injection cycles. Additionally, as the number of freeze–thaw cycles (Nc) increased, the total porosity and effective porosity of the coal cores increased linearly before stabilizing, while the residual porosity first steadily diminished and afterwards became constant. Furthermore, the variation in the total porosity and residual porosity of the coal cores continuously diminished with an increase in the level of metamorphism. The NMR permeability of the coal cores showed a similar pattern to the porosity. Accordingly, the optimal parameters for cryogenic L-CO2 cyclic injection during a complete working time were determined to be Nc = 4 and Pc = 30 min. A field test demonstrated that after L-CO2 cyclic freeze–thaw treatment, the average gas drainage concentration of a single borehole in the test region increased by 1.93 times, while the pure flow of a single gas drainage borehole increased by 2.21 times. Finally, the gas attenuation coefficient decreased from 0.036 to 0.012. We concluded that the proposed permeability enhancement technique transformed coal seams from hard-to-drain to drainable.

Modelling of the cyclic chemisorption-catalytic process for production of elemental sulfur and hydrogen from hydrogen sulfide

The research is devoted to simulation of cyclic chemisorption-catalytic process for H2S decomposition on the base of bulk FeS catalyst-chemisorbent. The performed simulation of the process has confirmed the possibility to create the stable cyclic non-stationary operation mode with a technologically acceptable duration of chemisorption/regeneration cycles (10-15 minutes and more). Though the maximum calculated per pass conversion of H2S was not higher than 30%, it is possible to achieve practically complete decomposition of H2S to hydrogen and sulfur by recirculation of unreacted H2S. The process may be performed at rather moderate temperatures (not higher 600-650°), it makes possible to use the conventional construction materials for process equipment with reasonable capital costs. The preliminary evaluation has demonstrated that the proposed process, being compared to conventional Claus process, will be characterized with better economic parameters due to the manufacturing of hydrogen which will have ∼5 times higher cost than that of produced sulfur. From the other side, the process may potentially provide the self-cost of the produced hydrogen quite competitive to that of conventional technologies such as conversion of hydrocarbons or water electrolysis. The technology may be applied at oil refineries and natural gas processing plants.

Failure-Mechanism and Design Techniques of Offshore Wind Turbine Pile Foundation: Review and Research Directions

Wind energy is one of the most sustainable and renewable resources for power generation. Offshore wind turbines (OWTs) derive significant wind energy compared to onshore installations. One of the greatest challenges encountered by installing the OWTs is the adequate design of their foundation in relatively soft and compressible marine soil. In most cases, the OWTs are supported by a single pile, termed as ‘monopile foundation’. Apart from the usual loads from the superstructure, these piles are subjected to complex loading conditions under static and cyclic modes in the axial, lateral, and torsional directions due to the primary actions of the wave, wind, and current. To incorporate an appropriate design methodology, understanding the failure mechanisms of such piles is of the utmost necessity. This review paper aims to focus on the progressive development in the analysis of failure mechanisms and design practice relevant to the monopile foundations for OWTs by theoretical and experimental studies conducted globally. An extensive literature survey has been carried out to study the gradual progress on offshore pile-soil interaction, failure mechanisms, and design techniques of OWT supporting monopile foundations. Based on the studies, a brief overview of the various aspects of analysis and design has been carried out, and the relevant conclusions are drawn therefrom.

Toz metalurjisi ile üretilen CoCrFeNiAl YEA'nın NaCl erimiş tuz içindeki sıcak korozyon davranışı

The present work reports the hot corrosion behavior of equimolar CoCrFeNiAl high entropy alloy (HEA) produced by powder metallurgy. The hot corrosion behavior of the HEA was characterized in severe conditions involving NaCl molten salt environment and cyclic mode. The mass gain of CoCrFeNiAl HEA after being hot corroded at 850°C for 120 h was about 2.2 mg/cm2. After 120 h of hot corrosion at 850°C, XRD analysis result revealed that the constituent phases of the scale formed on CoCrFeNiAl HEA were Al2O3, Fe2O3, Cr2O3, NiO and NiCr2O4. The corrosion scale mainly consisted of Cr2O3, and underneath this layer was dominated by a discontinuous thin layer of Al2O3. The role of NaCl on the hot corrosion mechanism was also discussed.

Lateral cyclic behavior of OWT tripod suction bucket foundation in clays

Tripod suction bucket foundations are increasingly used to support offshore wind turbines (OWTs) due to their economic advantages and high overturning resistance. In the harsh marine environment, OWT tripod bucket foundations are subjected to long-term lateral cyclic loads from wind, waves and current. However, the response of tripod bucket foundations in clay to cyclic lateral loads is not well covered in the literature. Therefore, a three-dimensional (3D) numerical method is developed for analyzing their lateral cyclic response based on a simplified bounding surface model of clay. The numerical model is validated by comparing its results with scaled model test results available in the literature. The validated model is then used to investigate the rotation mechanism of tripod suction bucket under lateral monotonic and cyclic loading. The ‘bonded contact’ and ‘separable contact’ were set between the soil plug and the inner wall to simulate the upper limit and the lower limit cases of the tensile capacity of the suction bucket. The influences of the bucket-soil contact condition, loading direction and cyclic loading mode (one-way and two-way) on the cyclic behavior were analyzed. It was found that these factors have a significant impact on the cyclic responses, permanent rotation angle and failure mechanism of the tripod bucket foundation. The findings from this study can provide guidance for the design of OWT tripod bucket foundations.

Soil degradations in the IGP of central Haryana, India-a spatial assessment for reclamation and management.

Natural and anthropogenic processes are primary drivers for soil degradations in the Gangetic plain of India. Indian Remote Sensing (IRS) data was used to assess soil degradations and study spatial changes comparing with the legacy datasets. Based on the nature, extent, and degrees of limitations, these soils were evaluated to suggest suitable reclamation and management options. Typical strong signature (white tones) from a barren highly salinized soil (P3, P6, P9, P11, and P15) and higher energy absorption (blue-black tones) from a permanent waterlogged surface (P13, P14, P10) in the irrigated areas have favored delineation of salt-affected, strong, and permanent waterlogged areas. Moderate and slightly salt-affected soils (P1, P2, P4, P5, P7, P8, and P12) and the areas with high water table depths (P13 and P14) have shown mixed spectral signatures for associations of soil, water, and crops and were mapped using ground truth and soil chemical analysis data. Irrigation with poor quality ground water (RSC: 1.2 to 12.3 me L-1) has prompted developing salinity and sodicity in P2, P5, and P11, while irrigation in poorly drained areas caused appearance of waterlogging (WTD < 1.5m) and salinization (P3, P5, P7, P9, P13, P14). The gypsum application and sub-surface drainage (SSD) techniques have enhanced soil reclamation by (i) neutralizing CO32 - and HCO3 - in P12 (pH 9.2, ESP 24) and (ii) controlling soil salinity (EC 3.0 dS m-1) and waterlogging (WTD > 1.5m) in P14. Soils with CaCO3 layers at shallow depth in P3 (0.7-4.2%), P6 (1.2-7.1%), P9 (8-16%), P11 (4-15%), and P13 (0.9-9.4%) were managed using forest plantations. Ground water with high SAR in T1 to T7 can be applied for agriculture using mixing or cyclic mode. Water with high RSC in T4, T5, T7, T8, T9, and T10 needs treatment with gypsum. A significant area (~ 24.87%) of salt-affected soils was reclaimed since 1971. Prominent changes (3.27 to 17.71%) were shown in Panipat and Karnal districts. Small areas of brick kiln (P11), industrial effluent (P10), riverine sand, partially stabilized dunes, and mining have appeared due to anthropogenic activities.

DIFFERENTIAL APPROACHES TO DIAGNOSTIC AND POSSIBLE REHABILITATION OF PATIENTS WITH PREMATURE OVARIAN FAILURE (clinical lecture)

Premature ovarian failure (POF) –pathological condition characterized by amenorrhea, infertility, symptoms of hypoestrogyny on the background of increased levels of gonadotropins (in women under 40 years. To fill the deficit of sex hormones in the POF is the most rational to apply traditional hormone replacement therapy in cyclic mode. The innovative method for the treatment of this category of patients is based on the use of dehydroepiandrosterone.

4-Amino modified derivatives of cytidine towards interactions with the methyltransferase enzyme

By the importance of exploring novel compounds for inhibiting the cancerous enzymes activities, this work was performed to recognize advantages of employing 4-amino modified derivatives of cytidine for participating in more efficient interactions with the methyltransferase (MTN) cancerous enzyme target. To this aim, four groups of modified models of cytidine were investigated in addition the original models to recognize the structural features and the corresponding activities. The 4-amino site of cytidine was functionalized by different carbon-based groups in linear and cyclic modes through a bridging peptide linkage. The models were optimized to reach the minimized energy structures by performing quantum chemical calculations and their interactions with the target were analyzed by performing molecular docking simulations. The obtained results of 4-amino modified derivatives of cytidine showed advantages of employing structural modifications to find structures with better molecular orbital based features. Formations of interacting complexes indicated that the additional of carbon-based groups helped to improve possibility of interactions between the substances in both of chemical and physical modes. As a remarkable achievement of this work, the model of cytidine with a phenyl group showed the best advantage of participating in interactions with the MTN target among all twenty five models of the investigated cytidine compounds.

Sector Mode Assembling Reduction Technique for High-Fidelity Blisk Models with Geometry Mistuning

Blade mistuning in blisks arises primarily from the scatters of blade geometry profiles caused by manufacturing tolerance, in-service wear, blade repairs, etc. There is a recent trend to capture the blade-to-blade geometry variances through precise geometry measurements by a 3D optical scanning system in order to obtain an improved blade geometric mistuning evaluation capability. However, this usually leads to prohibitive computational costs due to the large-scale, high-fidelity industrial blisk finite element models. This paper develops an original model reduction approach, Sector Mode Assembling Reduction Technique (SMART), specifically for the high-fidelity blisk model fully mistuned by blade geometric variances, with either topologically compatible or incompatible blade meshes. The basic idea of SMART is to construct the sector-level reduction mode basis by strategically assembling the truncated cyclic modes independently computed for each “isolated” sector with assumed cyclic symmetry at the sector interfaces. Benefiting from the block structure of the SMART mode basis, the reduced-order models are derived by a series of sector-level projections with a relatively low memory requirement and computational cost. Another hidden benefit is that the SMART approach enables efficient structural modification predictions of the global blisk modes because only the modes of the sectors undergoing blade modification need to be re-evaluated and replaced in the SMART mode basis. The SMART approach is applied into a high-fidelity “as-measured model” of a blended blisk, constructed upon the geometry measurement by the state-of-the-art 3D optical scanning technology. It is fully demonstrated that the reduced-order model derived by SMART, featured by a minimal size, is able to reproduce the dynamics of the full-order as-measured blisk model with high accuracy.

Mechanical characterization of a multi-layered zirconia: Flexural strength, hardness, and fracture toughness of the different layers

This study compared the flexural strength under monotonic (static - sσ) and cyclic load application (fatigue - fσ), hardness (H) and fracture toughness (KIC) of different layers of a multi-layered zirconia (IPS e.max ZirCAD MT Multi, Ivoclar). Each layer was sectioned, classified into three groups according to yttria content (4-YSZ, 4/5-YSZ and 5-YSZ), and shaped on samples for flexural strength and fracture toughness tests (bars: 1.0 × 1.0 × 11 mm); and Vickers hardness test (plates: 1.5 × 4.0 × 5.0 mm). Flexural strength under monotonic load application (sσ; n = 10) was obtained through two different devices (three-point-bending and ball-in-hole device) and fatigue flexural strength (fσ; n = 15; initial load: 10 N; step-size: 5 N; 10,000 cycles/step) was assessed using a ball-in-hole device under cyclic load application. Vickers hardness test (n = 5), fracture toughness test (n = 10), and additional analyzes (Finite Element Analysis - FEA, Energy-dispersive X-ray spectroscopy - EDS and Scanning Electron Microscopy - SEM) were also performed. No differences were found between the different devices in the monotonic flexural strength test, and FEA showed similar tensile stress distribution for the two devices. 4-YSZ showed higher values of flexural strength under monotonic and cyclic load application modes (sσ = 1114.73 MPa; fσ = 798.84 MPa), and fracture toughness (KIC = 3.90 MPa√m). 4/5-YSZ had an intermediate sσ; however, fσ was similar to 5-YSZ (404.00–429.36 MPa) and KIC similar to 4-YSZ (KIC = 3.66 MPa√m). No statistical differences were found for hardness and Weibull modulus for fatigue flexural strength data. The amount of yttria in the layer compositions increased from 4-YSZ to 5-YSZ, and larger zirconia crystals were observed in the topographic images of 5-YSZ. Failures in the flexural strength and toughness tests started from the face subjected to tensile stress. Different layers of the multi-layered zirconia blank presented distinct mechanical properties. 4-YSZ (cervical layer) presented the highest flexural strength under monotonic and cyclic loads (fatigue), and higher fracture toughness even similar to the transition layer (4/5-YSZ). Hardness was similar between the layers. The ball-in-hole device performed similarly to the three-point bending device and can be used as an alternative to the traditional method.

Inelastic response of thermo-oxidatively aged carbon black filled polychloroprene rubber. Part II: Mullins effect

The present investigation focuses on the effect of the elastomer network modifications in the elastomer network due to thermo-oxidative aging (as proposed in Part I) on the Mullins effect. A series of cyclic mechanical tensile loading modes are imposed on thermo-oxidatively aged specimens to understand the repercussions of crosslinking and chain scission on Mullins effect and its recovery. Mullins effect is characterized using two methods to assess the stress-softening occurring as a result of thermo-oxidative aging. The observations reveal that hysteresis, permanent set, Mullins effect, and its recovery are significantly affected by the change in elastomer network.

A Comprehensive Framework For Itu Next Generation Pons

Due to the higher number of Optical Network Units (ONU), the power dissipation of Next Generation Passive Optical Network (PON) has gradually risen. Several energy energy-saving schemes have been proposed by the International Telecommunication Union (ITU) such as Cyclic Doze Mode (CDM) and Cyclic Sleep Mode (CSM). The performance of the small capacity devices (nodes) is relying on traffic advent or arrival rate and traffic threshold on which Local Wakeup Indication (LWI) ignited. Thus, an investigative model of ONU to review different CSM / CDM control schemes need extremely important and as well as becoming a hot topic among the scientific community. The state-of-the-art models do not use the sleep buffer parameter that yields lower performance assessment of the CSM process at limited traffic advent rates. They are incapable to acquire the CSM / CDM process at the above traffic rates. The proposed work boosts the current Discrete-Time Markov Chain (DTMC) established power exhibit taking into account a parameter i.e. sleep buffer at each ONU. Additionally, it governs the LWI events at the ONU and as well as Optical Line Terminal (OLT). Furthermore, the suggested exhibit precisely measures the ONU sojourn in every CSM / CDM state, energy savings, and power dissipation of ONU which depends on the advent rate of traffic. According to the recommended model, a CSM / CDM framework is also supplemented to configure all the parameters effectively under the given average delay constraints.

Compact cyclic fiber three-mode converter based on mechanical fiber grating.

In this Letter, a compact cyclic mode converter (CMC) based on a mechanical fiber grating is proposed and fabricated to eliminate differential mode group delay and mode-dependent loss in the mode division multiplexing (MDM) transmission system. The proposed CMC can realize cyclical interchange of any input mode among the LP01/LP11a/LP11b modes, which requires only one mechanical grating. The mode conversion is evaluated by observing the mode field patterns of the fiber output. The experimental results prove that the introduction of CMC does not significantly degrade the transmission performance of the photonic lanterns back-to-back system. The insertion loss and the average cross talk of the whole system are lower than 5 dB and -11.3 dB, respectively. The proposed CMC provides a new method for reducing link damage in the MDM transmission system.

Anisotropic CdSe Tetrapods in Vortex Flow for Removing Non-Specific Binding and Increasing Protein Capture.

Non-specific binding (NSB) is one of the important issues in biosensing performance. Herein, we designed a strategy for removing non-specific binding including anti-mouse IgG antibody and bovine serum albumin (BSA) by utilizing anisotropic cadmium selenide tetrapods (CdSe TPs) in a vortex flow. The shear force on the tetrapod nanoparticles was increased by controlling the rotation rate of the vortex flow from 0 rpm to 1000 rpm. As a result, photoluminescence (PL) signals of fluorescein (FITC)-conjugated protein, anti-mouse IgG antibody-FITC and bovine serum albumin (BSA)-FITC, were reduced by 35% and 45%, respectively, indicating that NSB can be removed under vortex flow. In particular, simultaneous NSB removal and protein capture can be achieved even with mixture solutions of target antibodies and anti-mouse IgG antibodies by applying cyclic mode vortex flow on anisotropic CdSe TPs. These results demonstrate successfully that NSB can be diminished by rotating CdSe TPs to generate shear force under vortex flow. This study opens up new research protocols for utilization of anisotropic nanoparticles under vortex flow, which increases the feasibility of protein capture and non-specific proteins removal for biosensors.

Piezoresistive Properties of 3D-Printed Polylactic Acid (PLA) Nanocomposites.

An increasing interest is focused on the application of 3D printing for sensor manufacturing. Using 3D printing technology offers a new approach to the fabrication of sensors that are both geometrically and functionally complex. This work presents the analysis of the 3D-printed thermoplastic nanocomposites compress under the applied force. The response for the corresponding resistance changes versus applied load is obtained to evaluate the effectiveness of the printed layer as a pressure/force sensor. Multi-walled carbon nanotubes (MWNT) and high-structured carbon black (Ketjenblack) (KB) in the polylactic acid (PLA) matrix were extruded to develop 3D-printable filaments. The electrical and piezoresistive behaviors of the created 3D-printed layers were investigated. The percolation threshold of MWNT and KB 3D-printed layers are 1 wt.% and 4 wt.%, respectively. The PLA/1 wt.% MWNT 3D-printed layers with 1 mm thickness exhibit a negative pressure coefficient (NPC) characterized by a decrease of about one decade in resistance with increasing compressive loadings up to 18 N with a maximum strain up to about 16%. In the cyclic mode with a 1 N/min force rate, the PLA/1 wt.% MWNT 3D-printed layers showed good performance with the piezoresistive coefficient or gauge factor (G) of 7.6 obtained with the amplitude of the piezoresistive response (Ar) of about -0.8. KB composites could not show stable piezoresistive responses in a cyclic mode. However, under high force rate compression, the PLA/4 wt.% KB 3D-printed layers led to responses of large sensitivity (Ar = −0.90) and were exempt from noise with a high value of G = 47.6 in the first cycle, which is a highly efficient piezoresistive behavior.

Influence of Thermal Cyclic Treatment Modes on the Structure and Properties of SP80N4D2M Steel with a Nanosized Ni Additive

Influence of Thermal Cyclic Treatment Modes on the Structure and Properties of SP80N4D2M Steel with a Nanosized Ni Additive

Comparative research on cyclic ablation behavior of C/C-ZrC-SiC and C/C-ZrC composites at temperatures above 2000 °C

The cyclic and single ablation behavior of C/C-ZrC-SiC and C/C-ZrC composites prepared by reactive melt infiltration were studied. The ablation resistance properties of cyclic ablation of 30 s × 4 and single ablation of 120 s was similar to that of 60 s × 4 and 240 s. The oxidation of the matrix and the peeling content of oxides are aggravated with the increased cyclic ablation numbers. Under the cyclic ablation mode, C/C-ZrC-SiC composites showed lower mass loss than C/C-ZrC composites. At the single ablation of 240 s, C/C-ZrC-SiC composites showed desirable ablation resistance owing to the formation of an effective heat/oxygen protection layer on the ablated surface.