Sticking Effect Research Articles

Effect of Stick - Slip Phenomena between Human Skin and UHMW Polyethylene

The present paper investigates experimentally effect of applied load and different velocity on the coefficient of friction between two interacting surfaces (human skin and Ultra-high-molecular-weight polyethylene (UHMW- polyethylene) at static and dynamic friction. It is possible to conclude specific point based on the above practical part and frictional analysis of this investigation as the most important mechanical phenomenon was creep has been observed a stick time interval where the static friction force is significantly increased during this stroke. The analytical model for stick-slip of skin and UHMWPE is proposed. The difference between static and kinetic friction defines the amplitude of stick-slip phenomena. The contact pressure, the sliding velocity, and rigidity of system determine the stability conditions of the movement between skin and UHMWPE. Experiments were carried out by developing a device (friction measurement). Variations of friction coefficient during the time at different normal load 4.6 and 9.2 N and low sliding velocity 4, 5, 6 and 7 mm/min were experimentally investigated. The results showed that the friction coefficient varied with the normal load and low sliding velocity. At static friction, the coefficient of friction decreased when the time increases, whereas, at dynamic friction, the coefficient of friction decreased when the time increased at normal load 4.6 and 9.2 N.

Study on high quality surface finishing technology of pre-spinning nozzle in additive manufacturing

Through the simulation of abrasive flow in the inner cavity of the superalloy pre-spinning nozzle made by additive manufacturing, the special abrasive polishing tool is optimized and the surface polishing technology of the inner cavity of typical structure test pieceis studied. Through comparison of the surface morphology before and after polishing, it can be concluded that the abrasive flow has a considerable removal effect on the powder sticking effect, spheroidizing effect, step effect, slag hanging phenomenon and residual support on the surface of parts, but it has a limited effect on the surface pit of the substrate. After polishing, the surface roughness of the inner cavity of parts decreasea from Ra 3.1397 μm to Ra 0.5805 μm, and the surface roughness of blade position decreases from Ra 4.8473 μm to Ra 0.3606 μm. Through the range analysis, it is found that the effect intensity of the processing parameters on the surface roughness of the parts is in order of the processing time, processing pressure and abrasive particle size.

Evaluating the Effects of Biochar with Farmyard Manure under Optimal Mineral Fertilizing on Tomato Growth, Soil Organic C and Biochemical Quality in a Low Fertility Soil

Biochar amendments are widely recognized to improve crop productivity and soil biogeochemical quality, however, their effects on vegetable crops are less studied. This pot study investigated the effects of cotton stick, corncob and rice straw biochars alone and with farmyard manure (FYM) on tomato growth, soil physico–chemical and biological characteristics, soil organic carbon (SOC) content and amount of soil nutrients under recommended mineral fertilizer conditions in a nutrient-depleted alkaline soil. Biochars were applied at 0, 1.5 and 3% (w/w, basis) rates and FYM was added at 0 and 30 t ha−1 rates. Biochars were developed at 450 °C pyrolysis temperature and varied in total organic C, nitrogen (N), phosphorus (P) and potassium (K) contents. The results showed that biochars, their amounts and FYM significantly improved tomato growth which varied strongly among the biochar types, amounts and FYM. With FYM, the addition of 3% corncob biochar resulted in the highest total chlorophyll contents (9.55 ug g−1), shoot (76.1 cm) and root lengths (44.7 cm), and biomass production. Biochars with and without FYM significantly increased soil pH, electrical conductivity (EC) and cation exchange capacity (CEC). The soil basal respiration increased with biochar for all biochars but not consistently after FYM addition. The water-extractable organic C (WEOC) and soil organic C (SOC) contents increased significantly with biochar amount and FYM, with the highest SOC found in the soil that received 3% corncob biochar with FYM. Microbial biomass C (MBC), N (MBN) and P (MBP) were the highest in corncob biochar treated soils followed by cotton stick and rice straw biochars. The addition of 3% biochars along with FYM also showed significant positive effects on soil mineral N, P and K contents. The addition of 3% corncob biochar with and without FYM always resulted in higher soil N, P and K contents at the 3% rate. The results further revealed that the positive effects of biochars on above-ground plant responses were primarily due to the improvements in below-ground soil properties, nutrients’ availability and SOC; however, these effects varied strongly between biochar types. Our study concludes that various biochars can enhance tomato production, soil biochemical quality and SOC in nutrient poor soil under greenhouse conditions. However, we emphasize that these findings need further investigations using long-term studies before adopting biochar for sustainable vegetable production systems.

Mimicking a Cellular Environment for RNA Folding Studies

The complexity of the cellular environment is difficult to replicate in vitro. Inert macromolecules such as dextran, Ficoll, and polyethylene glycol (PEG) are common in vitro crowders, but by themselves do not reproduce in-cell biomolecular interactions. Dilute cell lysates or lysis buffer replicate sticking trends observed in cells but do not account for crowding. Recently, we demonstrated that a combination of 150 mg/ml Ficoll and 60% lysis buffer could be used as an in vitro mimic that accounts for both steric crowding and non-steric sticking effects on cytoplasmic protein stability and kinetics.

(V)TEAM for SPICE Simulation of Memristive Devices With Improved Numerical Performance

The paper introduces a set of models of memristive devices for a reliable, accurate and fast analysis of large networks in the SPICE (Simulation Program with Integrated Circuit Emphasis) environment. The modeling starts from the recently introduced TEAM (ThrEshold Adaptive Memristor Model) and VTEAM (Voltage ThrEshold Adaptive Memristor Model). A number of improvements are made towards the stick effect elimination and other numerical refinements to make the analysis of large networks fast and accurate. A set of models are proposed that utilize the synergy of several techniques such as window asymmetrization, integration with saturation, state equation preprocessing, scaling, and smoothing. The performance of models is tested in Cadence PSPICE 17.2 and particularly in HSPICE v2017, the latter on a large-scale CNN (Cellular Nonlinear Network) for detecting edges of binary images. The simulations manifest the usability of developed models for fast and reliable operation in networks containing more than one million nodes.

Numerical study of droplet evaporation on heated flat and micro-pillared hydrophobic surfaces by using the lattice Boltzmann method

The evaporation processes of sessile droplets on both heated flat and structured hydrophobic surfaces are numerically studied by using a thermal multi-phase lattice Boltzmann model. The contact-line dynamics and heat transfer regarding the evaporation of droplets are simulated and the effects of the heat conductivity, wettability, and roughness of the substrate on the droplet evaporation are investigated. The results indicate that the different evaporation modes of the droplets on the rough surfaces are attributed to the microscopic “stick–slip” motion of the contact line. The constant contact angle (CCA) mode of droplet evaporation on the rough hydrophobic surface can be regarded as a macroscopic average of the microscopic “stick–slip” processes with a short stick period and small change in apparent contact angle. The weaker stick effect of the surface with a higher hydrophobicity and smaller solid fraction makes the droplet evaporation more likely to occur in the CCA manner.

Fostering Students’ Speaking Ability through Traditional Talking Stick

The research was about the effectiveness of Traditional Talking Stick to foster students’ speaking ability on eight-grade of MTs Salafiyah Syafi’iyah in the 2018/2019 academic years. This study aimed to determine the effectiveness of the Traditional Talking Stick teaching method on students speaking abilities, before and after using the Traditional Talking Stick method. There were 36 students as samples in this study. Researchers used a quasi-experimental using 4-times pre-test and 4-times post-test design. The data of this study was collected from observation and speaking tests (pre-test and post-test). The data analysis was then performed using a T-test (paired simple test) facilitated by SPSS 16.0. The results of this study were (1) the average scores of students’ pre-test on their speaking ability before using Traditional Talking Stick were 28,61 of pretest 1, 30,97 of pre-test 2, 33,92 of pre-test 3, 36,69 of pre-test 4-with all the of unsuccessful criteria. (2) the students’ average scores of speaking ability after being taught using Traditional Talking Stick were 75,6 of post-test 1, 77,86 of post-test 2, 82,28 of post-test 3, 84,89 of post-test 4-with all of the success criteria. (3) The result of the students’ average scores shown that there is a significant effect of the Traditional Talking Stick in students’ speaking ability after-treatment. It is as explained from the gained of obtained pretest 4 and post-test 4 average scores, in which t-count is -75,302 (at df = 35) and t table = 2, 03011, which means that the result of the SPSS calculation has been successful.

Disturbance estimator and smith predictor-based active rejection of stick–slip vibrations in drill-string systems

ABSTRACTStick–slip vibrations are widespread and hazardous phenomena in drilling practice. The objective of this paper is to develop a simple and general control strategy to minimise such vibrations together with unknown disturbances. Taking into account the transmission delay of the torsional energy from the surface to downhole, a neutral-type drill-string model is established and applied rather than a lumped-parameter model that cannot provide satisfactory modelling precision. Based on this neutral-type model, the major contribution consists of the combination of disturbance estimator and smith predictor to develop a robust vibration control scheme for drill-string systems. One conspicuous advantage of this scheme is that the effects of stick–slip vibrations and external disturbances are estimated without the need for any prior knowledge in the control input channel, and are offset correspondingly. Simulations confirm that this control scheme can achieve effective suppression of stick–slip vibrations with good tracking and disturbance rejection performance.

Effect of auricular acupoint sticking and pressing on postoperative pain of patients with mixed hemorrhoids：A Meta-analysis

Effect of auricular acupoint sticking and pressing on postoperative pain of patients with mixed hemorrhoids：A Meta-analysis

Effect of Sport-Specific Constraints on Aerobic Capacity in High School Field Hockey Players.

Roberts, AH, Walden, AJ, Carter, KA, and Symons, TB. Effect of sport-specific constraints on aerobic capacity in high school field hockey players. J Strength Cond Res 36(2): 493-497, 2022-Many sports require the use of a mouth guard (MG) and carrying an object during play. Research has shown that individually these conditions can cause performance decrements; however, no research has been conducted into the effect of combining both mouth guard and stick with adolescent female field hockey players. This study aimed to determine the effects of MG and stick (STK) use on estimated aerobic capacity over the course of a season long training and competition period. Thirty-eight female high school field hockey players were separated into 2 groups: experimental (EXP-all training with MG-STK) or control (CTL-all training without MG-STK). Aerobic capacity was estimated using a multi-stage fitness test. Field hockey specific training prescribed by coaching staff was performed throughout the study, with testing at pre-, mid- and post-season. Subjects performed 2 sets of testing at each time point, first without MG-STK (WOMG-STK) and then with MG-STK. No main effect was observed in aerobic capacity estimations between groups; however, MG-STK testing reduced estimated aerobic capacity at each time point, regardless of the group (WOMG-STK: 37.4 ± 6. mL·kg-1·min-1 vs. MG-STK: 33.2 ± 4. mL·kg-1·min-1; p < 0.01). Chronic use of MG-STK does not seem to negatively impact estimates of aerobic capacity over the course of a season in high school field hockey players. Therefore, players should be encouraged to use MGs during all training sessions as it increases safety and familiarity with no decrement in long-term physiological performance.

Reduction of Tape Sticking Effect on Leadframe Platform for Thin Applications

Reduction of Tape Sticking Effect on Leadframe Platform for Thin Applications

Effects of stick–slip transition on polymer melt apparent shear viscosity measurement

ABSTRACTA twin‐bore capillary rheometer is used for the apparent shear viscosity measurement of commercial polyolefin melts based on Ostwald‐de Waele model. The effects of stick–slip transition of linear low‐density polyethylene (LLDPE) and high‐density polyethylene (HDPE) are investigated. The maximum error of apparent shear viscosity calculated by corrected shear rate is 23% when the stick–slip transition occurs. Based on the entanglement‑disentanglement theory, a schematic diagram for shear stress curve containing stick–slip transition is presented to illustrate polymer melt flow in capillary. In this study, the critical stress at the beginning of stick–slip transition at 220 °C is 23.01 kPa higher than that at 190 °C, and why it increases with increasing temperature is discussed with a molecular mechanism in combination with entropy elasticity and entanglement‑disentanglement theory. Through the analysis of ULDPE, PS, EVA, and K‐Resin, it can be found that short branches or side groups are helpful to avoid the stick–slip transition. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48230.

Development of a direct ESI-MS method for measuring the tannin precipitation effect of proline-rich peptides and in silico studies on the proline role in tannin-protein interactions

Tannins are a heterogeneous class of polyphenols that are present in several plants and foods. Their ability to interact and precipitate proline-rich proteins leads to different effects such as astringency or antidiarrheal activity. Thus, evaluation of the tannin content in plant extracts plays a key role in understanding their potential use as pharmaceuticals and nutraceuticals. Several methods have been proposed to study tannin-protein interactions but few of them are focused on quantification. The purpose of the present work is to set up a suitable and time efficient method able to quantify the extent of tannin protein precipitation. Bradykinin, chosen as a model, was incubated with increasing concentrations of 1,2,3,4,6-penta-O-galloyl-β-d-glucose and tannic acid selected as reference of tannic compounds. Bradykinin not precipitated was determined by a mass spectrometer TSQ Quantum Ultra Triple Quadrupole (direct infusion analysis). The results were expressed as PC50, which is the concentration able to precipitate 50% of the protein. The type of tannin-protein interaction was evaluated also after precipitate solubilisation. The involvement of proline residues in tannin-protein interactions was confirmed by repeating the experiment using a synthesized peptide (RR-9) characterized by the same bradykinin sequence, but having proline residues replaced by glycine residues: no interaction occurred between the peptide and the tannins. Moreover, modelling studies on PGG-BK and PGG-RR-9 were performed to deeply investigate the involvement of prolines: a balance of hydrophobic and H-bond contacts stabilizes the PGG-BK cluster and the proline residues exert a crucial role thus allowing the PGG molecules to elicit a sticking effect.

Multi-dimensional semi-analytical model for axial stick–slip of a rod sliding on a surface with Coulomb friction

A multi-dimensional lumped element model of a long non-rotating rod that moves on a slick surface with both dynamic and static Coulomb friction is outlined. The rod is accelerated to a constant velocity, and the free end of the rod experiences the effect of stick and slip. This article describes a new modeling approach, where the model is able to switch between different linear semi-analytical sub-models, depending on how much of the rod is moving. Fundamental understanding of the stick–slip effect is revealed, and a potential shortcoming of the model is also discussed. The model is computationally effective and may be suitable for real-time applications in, for instance, oil-well drilling.

Reduced ionic effect and accelerated electro-optic response in a 2D hexagonal boron nitride planar-alignment agent based liquid crystal device

The presence of excess free-ion impurities in liquid crystals (LCs) gives rise to a number of problems in the electro-optical liquid crystal displays (LCDs), e.g., slow electro-optical responses and image sticking effects. Here we experimentally present that the two-dimensional (2D) hexagonal boron nitride (h-BN) nanosheet can serve as a planar-alignment agent and as an ion-capturing agent at the same time in an electro-optic LC device. The 2D h-BN nanosheet is employed as a planar-alignment agent on one side of an LC cell, where the standard planar-aligning polyimide (PI) layer is used on the other side of the cell. The LC exhibits uniform planar-alignment in this h-BN/PI hybrid device. It is found that the free-ion impurities in the LC are significantly suppressed in this h-BN/PI hybrid cell compared to that in a standard PI/PI LC cell. The free-ion density is reduced in the hybrid cell due to the 2D h-BN nanosheet’s ion-capturing process. The reduction of ionic impurities results in an accelerated electro-optic response of the LC in the h-BN based hybrid cell—which may have potential application for faster electro-optic devices.

Feasibility study of using a semiactive electromagnetic friction damper for seismic response control of horizontally curved bridges

Semiactive control systems have been found to be more effective than passive and active control systems for seismic protection of bridges because of their reliable and adaptable characteristics. This paper presents a comprehensive investigation on the modeling and design of a semiactive electromagnetic friction damper (SEMFD) for the seismic response control of horizontally curved bridges. The proposed SEMFD possesses a simple configuration consisting of a ferromagnetic plate and two arrays of ferromagnetic core coils (FCs) attached to the two sides of the ferromagnetic plate through two friction pads. The attractive magnetic interaction between the FCs arrays and the ferromagnetic plate creates the normal force, which generates friction force as the friction pads and the ferromagnetic plate move relative to each other. The magnitude of this force can be controlled by varying the control current passing through the FCs. This semiactive controller, designed based on the optimal linear quadratic Gaussian control method, is capable of reducing the undesirable effects of stick–slip motion in the damper, while restoring the piston of the SEMFD to its initial position at the end of the excitation. The capability of the proposed SEMFD to mitigate the rigid-body motion of decks of horizontally curved bridges is demonstrated by implementing it into the dynamic model of a horizontally curved bridge prototype. The numerical results indicate that the proposed SEMFD is effective in limiting the motion of the deck and thereby preventing it from unseating, which is one of the most common modes of failure among horizontally curved bridges.

Electromechanical bending microactuator as optical shutter

This paper presents the design, fabrication methods and characterization of a thin film electromechanical optical shutter. The overlap of the optical channel 1.4 mm high is provided by a multilayer film structure of the cantilever, which profile is determined by the residual internal stresses of the films. In the process of design analysis, the actual parameters of the strained structural layers, the temperature dependence of the curvature, the undamped natural frequencies and the damping parameters of the film cantilever were determined. Correlation of the data shows that the experimental results fit the theoretical data sufficiently closely. The developed control circuit is designed to compensate for the induced dielectric polarization and prevent the control voltage rise and the cantilever sticking effect. The design presented in this publication enables development of a simple and effective electromechanical optical shutter having interruption aperture height which exceeds 1.4mm.

NMO residual reduction on medium anisotropy in field “X” using Fomel and Stovas method

It has been done the study of reducing NMO residual on medium anisotropy in Field “X” by using Fomel and Stovas method. The anisotropic medium affected the seismic prestack of near, mid, and far offset when the NMO correction was being conducted. The correction principally used the isotropic medium approach where the seismic event often encountered problems in its far offset. The problem was the seismic trace appearance in form of hockey stick and NMO-stretching. The purpose of this study is to understand the best residual value of travel time by Fomel and Stovas, Alkhalifah, and conventional hyperbolic methods. The semblance analysis was usedlongside all three methods to obtain the value of Vnmo and anisotropy (η). The values were then compared. The result shows that the non-hyperbolic Fomel and Stovas method is better in reducing residual NMO as indicated by the smaller residual value compared to Alkhalifa and conventional hyperbolic methods of travel time. The small residual contributed to eliminate the effect which was caused by anisotropy medium like hocky stick effect.

Dynamic identification of tangential contact stiffness by using friction damping in moving contact

Abstract Interactions at interfaces play a pivotal role in the mechanics of fractured materials as well as joint interfaces. Therein, the dry friction and stick-slip effects will serve as essential factors of a certain nature. Here, we focuses on the investigating of transition process from adhesion to sliding between two rough surfaces during reciprocating moving contact. A measurement system for friction damping is designed to identify the key parameters of tangential contact stiffness associated with the transition process. A tangential contact stiffness model is proposed to describe the mating rough surfaces by considering the effect of sticking and sliding. As a result, the tangential contact stiffness can be obtained through the compiled calculation procedure.

Poly L-Dopa/poly(ethylenedioxythiophene) as a novel mussel-inspired electroactive binder for environmentally friendly hybrid supercapacitors

3,4-Dihydroxy-L-phenylalanine and ethylenedioxythiophene were chemically copolymerized via an oxidative process in aqueous solution. The copolymer was used as a novel mussel-inspired electroactive binder in conjunction with a nickel-based metal organic frame work for fabrication of environmentally friendly supercapacitors. The binder, in addition to the sticking effect, contributes to electric charge storing via the redox process of catechol moieties of poly(3,4-dihydroxy-L-phenylalanine) and also the formation of a high charge-storing double layer due to the presence of poly(ethylenedioxythiophene). Cyclic voltammetry, charge/discharge measurements, and electrochemical impedance spectrometry showed that the hybrid supercapacitors based on Ni-benzidine MOF with the new electroactive binder exhibit very high specific capacitance (770 F g$^{-1}$ at 1 A/g) and remarkable capacitance retention of more than 94% after 1000 cycles and 86% after 5000 cycles at high current density of 5 A g$^{-1}$.