Passive Resistance Research Articles

Organic-inorganic composite passivation and corrosion resistance of zinc coated NdFeB magnets

An organic-inorganic composite passivation of Zn coated NdFeB magnets was carried out using Ce-containing compound and organosilane as source materials. Effects of organosilane content on the microstructure of composite passivation layer were analyzed, and the corrosion resistance and corrosion mechanism of the passivated Zn/NdFeB specimens were deeply studied. Composition, elemental distribution, phase structure and morphology of the specimens were characterized by X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. The corrosion resistance of the specimens was studied by polarization curves, electrochemical impedance spectroscopy, neutral salt spray text and mass gain test. Results show that adding an appropriate amount of organosilane during the passivating process can form a passivation layer composed of Ce, Si, and O. The optimized Zn(CS-1)/NdFeB achieves the longest NSS time of 840 h, which is twice that of Zn(Ce-5)/NdFeB specimens. Organosilane can build a framework for the passivation layer and make the passivation layer more compact. During the corrosion process, the corrosion medium invasion path is long due to the support of the organosilane frame on the surface, so the corrosion resistance of Zn(CS)/NdFeB is greatly enhanced.

Self-healing epoxy composite coating based on polypyrrole@MOF nanoparticles for the long-efficiency corrosion protection on steels

In this work, a simple strategy was applied to modify zeolitic imidazolate framework-8 (ZIF-8) by the conductive polypyrrole (PPy) through in-situ polymerization. The synthesized PPy@ZIF-8 composite material as an active filler has been added into epoxy resin (EP) to produce a long-term anti-corrosion coating. The corrosion resistance of PPy@ZIF-8/EP coating was evaluated by electrochemical impedance spectroscopy (EIS) test and salt-spray test. The results showed that the introduction of the filler significantly improved the anti-corrosion performance of EP. After 30-day immersion in 3.5 wt% NaCl solution, the PPy@ZIF-8/EP coating showed a high impedance modulus of |Z|0.01 Hz (3.7 × 108 Ω cm2), which was four orders of magnitude higher than the neat EP. The improvement in corrosion protection could be attributed to the synergistic combination of passive and active corrosion resistance mechanisms. The PPy@ZIF-8 particles could not only be used as a passive nanofiller against corrosion media but also display a self-healing behavior due to the formation of the passivation iron oxide and Zn(OH)2 deposition layer on the steel substrate by electrochemical reactions, after the corrosion media reached the metal. This study provides new insight into the development of multifunctional anti-corrosion coatings for engineering applications.

Analytical method for determining displacement and bending moment of embedded cantilever retaining walls subjected to pseudo-static earthquake accelerations

The performance of embedded cantilever retaining (ECR) walls, such as the diaphragm and sheet-pile walls, is measured by the permanent displacement they experience during an earthquake. In the conventional design methods, the embedment depth is derived by checking the wall's stability against a probable collapse mechanism and applying safety factors. Thereby, these methods are incapable of determining the wall displacement. The present study proposes an analytical method based on the pseudo-static approach for calculating the earthquake-induced permanent displacement of ECR walls in cohesionless soils. A displacement-dependent earth pressure mobilization relationship, where the earth pressure mobilization is a function of the wall displacement, is used to derive the passive resistance on the excavated side of the wall. With increasing earthquake acceleration, active soil pressure on the retained side of the wall increases and drives the wall towards the excavated side, which causes further mobilization of passive earth pressure; thus, the wall stability is maintained. In observations from past experimental studies, the required embedment depth is derived by assuming rigid rotation of the wall about a point near the wall base and balancing the forces and moments acting on the wall. Analytical expressions are provided for determining bending moment distribution along the wall height. The proposed results are compared with those of the available experimental and numerical studies, and they exhibit good agreement, which substantiates the validity of the proposed method. Parametric studies were performed to investigate the influence of soil friction angle, wall roughness, the magnitude of the horizontal and vertical earthquake accelerations on the wall displacement and internal forces of the wall.

Comparisons of I- and Cl- concentrations on the corrosion behavior of TA4 titanium alloy in azeotropic acetic acid solutions

The corrosion problems of TA4 titanium alloy trays were urgent to be solved in the safe and steady production process of the acetic acid distillation column. According to the real corrosion environment of the distillation column, the corrosion behavior of TA4 titanium alloy in simulated azeotropic acetic acid solutions with a series of I- and Cl- concentrations was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The experimental results showed that the TA4 titanium alloy was much easier to be corrosive with I- and Cl- in the test solution, the passive film resistance R f, the charge transfer resistance R ct, and Warburg impedance W decreased obviously with the increasing concentration of I- and Cl-. The corrosion rate of Cl- was 1.79 times higher than I- on average when the I- and Cl- concentration increased from 0.1 wt.% to 5 wt.%. The inhibition of passive film formation on the surface of TA4 titanium alloy by Cl- is stronger than that of I-.

Quasi-Static Cyclic Testing of Hybrid Posttensioned Bridge Column Supported on a Monopile Foundation

In this research, a low-damage posttensioned rocking solution referred to as dissipative controlled rocking (DCR) connection is proposed for bridge columns supported on monopile foundations. The DCR connection is a low-damage system that replaces the plastic hinge mechanism in a column and aims to minimize and potentially eliminate the repair time and costs after an earthquake. A DCR bridge system combines unbonded posttensioning and replaceable dissipaters to provide self-centering and energy absorption capabilities, respectively. Current research on DCR column systems has focused on the performance of bridge bents founded on a fixed foundation, neglecting soil damping effects. In this research, a one-third scaled bent supported on a monopile with passive soil resistance was tested under quasi-static cyclic loading to validate the lateral seismic response of a DCR bridge bent with the contribution of the soil–foundation–structure interaction. When developing the details for the DCR connection, particular emphasis was made on utilizing conventional construction materials and forms for a low-damage bent that yields a similar construction cost to a monolithic joint. Nevertheless, the proposed DCR connection can be easily and quickly repaired or replaced after a significant seismic event. The performance of the bent was compared against a benchmark structure with an emulative connection type that resembles a monolithic cast-in-place joint. Results from testing suggest a greater performance of the low-damage DCR column. The dynamic response of the DCR column built on a flexible foundation differed from that of a fixed-base structure, which is primarily due to the energy dissipation capability of the flexibly supported structure. Flexibility in the soil foundation increased the structural period of the structure and reduced the seismic response of the DCR column. Damage to the DCR bent was limited to concrete crushing at the rocking interface, which proved to be easily repairable. In contrast, the bent with an emulative connection developed plastic hinging at the bottom of the column, which was nonrepairable.

The Working Cycle of the Motoring Internal Combustion Engine by a New Method with Cylinder Pressures as in Real Engine Operation

Abstract The current standard methods of determining the mechanical losses of the ICE by motoring do not correspond to the low pressures in the cylinders of real engine operation. The new tried and tested method of determining passive resistances by motoring ICE with high working pressures in the cylinders is based on blowing doses of compressed air into the cylinders around BDC with special self-acting valves. When motoring with the new method, the same course of pressures in the cylinders and the same load on the crank mechanism, including the piston group, is achieved during combustion. The measurement proved the problem-free functionality of the self-acting valves, and the conducted experiments provided data on the dependence of mechanical and heat losses in the ICE on the working pressures in the cylinder.

Pressure shafts of hydro power plants – Bridging a single fissure in the rock mass

AbstractIn a former paper of the authors a concept for dimensioning pressure shafts, considering the passive resistance of rock‐mass, has been developed. The assumption made there was that many cracks are distributed evenly over the circumference. The width of a single fissure was estimated by a reduction factor on the cumulated width of cracks. This question was now investigated analytically on basis of common mechanical principles and was confirmed by FE calculations. On hand of examples a dimensioning concept for bridging a single fissure by the steel lining has been developed. In the annex questions frequently arising over the planning process are discussed. It is intended to facilitate an overall judgement of the individual system by better knowledge of the complex relations.

Modified pseudo-dynamic based soil-structure interaction of caisson with a novel 3D failure wedge

Passive resistance computation for caissons embedded in layered soil is a complicated problem. In the present study, modified pseudo-dynamic method of analysis has been used to determine both amplification of earthquake waves through the soil strata and the resulting passive earth pressure on the embedded structure. The failure wedge has been idealized based on the results of experimental and numerical studies by previous researchers as log-spiral in vertical plane and oval in the horizontal plane. Earthquake waves are assumed to propagate harmonically in vertically upward direction through layered strata considering modified pseudo-dynamic approach with the entire failure wedge assumed to be lying in a single soil layer. Both, dry and submerged soil conditions, have been considered in the present study. The effect of increase in volume of failure wedge compared to corresponding plane strain condition on earth pressure coefficient has also been discussed in the current study. The earth pressure coefficient due to unit weight component has been reported. The earth pressure coefficient obtained from the current study for structures of different widths are found to be smaller in magnitude than corresponding pseudo-static analysis results.

Formation and Long-Time Exposure Aging of Oxides on Ni-Cr and Ni-Cr-X (Mo, W) Alloys in Acidic Chloride Solutions: Ramifications Towards Local Corrosion Resistance

Ni-Cr-based alloys are considered amongst the most corrosion-resistant when utilized in aqueous marine applications. The superior corrosion resistance of these alloys is known to depend on the presence of a homogeneous solid solution and the desirable attributes of their oxide films. However, the scientific basis for excellent passivation and protection against localized corrosion initiation remains uncertain and insights are often based on short term laboratory testing under limited conditions even though exposures are long-term. The engineering basis for alloy choice often relies on lab testing, field exposures or empirical metrics such as the PREN that do not even consider exposure time. Both highly engineered legacy and emerging alloys lack information on the precise attributes of protective passive films after long-time exposures. However, relevant field exposure periods are nearly infinite in time.The focus of the current work was on solid solution Ni-22Cr, Ni-22Cr-6Mo, and Ni-22Cr-6Mo-3W alloys. Potential step passivation studies in 0.1 NaCl pH 4 solutions in the passive range were investigated over 10s to 10 days at select potentials. To characterize the formation and exposure aging of oxide films, electrochemical methods were used as well as XPS and three-dimensional APT. Improvements in passive films protectiveness was correlated Cr3+ enrichment and aliovalent cation accumulation (Figure 1), and minimal morphological roughening. There is possibility of either oxide doping and/or phase separation promoted by aliovalent cations associated with alloying with Mo and W. Ni2+ rich oxides and hydroxides were preferentially dissolved with time. The most corrosion resistant alloys possess passivating films that are efficacious not only just after formation, but that self-healing capabilities and improve over long exposure times as evident from impedance spectroscopy and metastable pit studies. Such alloys were observed to be the most resistant when interrogated for local corrosion after various periods of exposure compared to other alloys whose impedance response degraded over exposure time. The latter alloys eventually arrived at conditions favoring breakdown.This work contributes to the scientific understanding of the long-term passivation process in Ni-based alloys in acidic chloride-containing environments. The presence of Mo and W as minor alloying elements on aqueous passivation and localized corrosion resistance initiation and stabilization correlated with certain features of electrochemically grown oxide films. Oxide exposure aging time, potential, and oxide “transformation” diagrams are introduced and shown to provide valuable insights on alloy. Passivated films may form as solute captured solid solutions after short term passivation or when grown quickly but are gradually enriched in Cr, Mo and W over long time. Can such Cr enrichment continue during exposure without limits? Factors affecting and limiting Cr enrichment are discussed as time allows.This work was supported by the Office of Naval Research under MURI “Understanding Atomic Scale Structure in Four Dimensions to Design and Control Corrosion Resistant Alloys” through Northwestern University #SP0028970-PROJ0007990-MURI ONR N00014-16-1-2280. Figure 1

Factors Influencing Bank Customers’ Orientations toward Islamic Banks: Indonesian Banking Perspective

During the COVID-19 pandemic, the Indonesian banking industry showed positive performance, high profitability, sustainable growth, and stability. Islamic banks grew by 9.50% and had a market share of 6.52 percent as of September 2021. This study aims to examine the industrial sector perspective on the factors that prevent consumers from becoming customers of Islamic banks, in particular the factors that influence consumer decisions not to become Sharia bank customers. This study used descriptive qualitative methods and in-depth interviews to confirm and obtain input from industry representatives regarding Islamic banks. Primary data collection was performed using a purposive sampling technique. Informants were head office officials, managers, heads of individual retail product development units, product features and policies, market education, marketing, customer acquisition, and individual retailers. The findings of this study are the existence of passive resistance of consumers to become customers of Islamic banks. In addition, there are obstacles for prospective customers of Islamic banks in responding to marketing stimuli due to the perception of risk, image, and weak marketing reach that have dominated passive resistance to Islamic banks (blocking effects). As a result, consumers prefer conventional banks and are less interested in becoming customers of Islamic banks. This means that there is no opposition to Islamic banks.

Numerical modeling of geosynthetic reinforced soil retaining walls with different toe restraint conditions

This paper reports numerical modeling of the prototype geosynthetic reinforced soil (GRS) walls corresponding to four centrifuge models that have different toe restraint conditions. The development of the interface stresses and displacements at wall toe during wall construction is investigated to understand how the toe carries load in the GRS walls with a practical toe structure. The numerical results show good agreement with the data from the centrifuge modeling. For the GRS walls with a leveling pad embedded in foundation soil, the shear resistance at the facing block-leveling pad interface acts as the toe resistance to counterbalance a portion of horizontal earth load, while the leveling pad-foundation soil interface play no role in wall performance because the soil passive resistance in front of the leveling pad inhibits the development of the shear stress and displacement on this interface. For the GRS walls with an exposed leveling pad, it is the leveling pad-foundation soil interface that works for carrying the earth load because the wall is more likely to slide along this weaker interface. The contribution of the toe to load capacity depends on the shear strength of the effective toe interface that contributes to the resistance against the earth load.

Tailoring mechanical and surface properties of UFG CP-Ti by the low-temperature annealing

This work offers the approach to exploit simple and cost-effective low-temperature annealing treatment to simultaneously enhance of hardness, corrosion and biological response of the ultra-fine grained commercially pure titanium (UFG CP-Ti) fabricated by multiple-pass cold rolling technique. Performed investigations revealed that improvement of all of these characteristics was possible by subjecting UFG CP-Ti to the heat treatment with parameters 250 °C/15 min. Hardening (for about 4.2 %) was governed by both partial recovery process of UFG structure and segregation of impurities atoms during annealing. Thereby, this beneficial effect was achieved only in titanium with a certain level of impurities (UFG Ti Grade 2). Enhancement of the corrosion resistance in fluoridated medium (increase of the passive layer resistance Rp from 0.28 ± 0.16 to 3.48 ± 0.18 MOhm*cm2) and osteoblast-like response was closely related to the thermally-induced changes in the passive layer characteristics e.g. growth of its thickness (from c.a. 6 to 11 nm) and changes in the nanotopography (increase arithmetic deviation of surface roughness Ra from 5 ± 1 to 10 ± 2 nm). Overall results indicate that the low-temperature annealing is an effective way to improve both bulk and surface properties of biomedical UFG CP-Ti, which could be easily transferred to the industrial scale.

La resistencia a la dominación de los indígenas de La Española (1492-1533)

This article analyzes the different forms of resistance that the Tainos of Hispaniola deployed against the Castilian domination. The active resistance, violent, was scarce and late compared to the great passive resistance that was manifested since the arrival of the Spaniards. After the failed uprisings of the first years, the Taino tenacity adopted some basic strategies, given the inability to stop the destruction of their world: one, the practice of scorched earth, with the idea of expelling foreigners for lack of food: two, the flight to the mountains, absenting themselves from the haciendas and mines. And three, suicide, which they resorted to when they became aware of the imminent end of their world and their new servile situation. It will be necessary to wait almost two decades to find an active resistance, that of the hispanized cacique Enriquillo.

Pullout behavior of a bearing polymeric strap under monotonic and cyclic tensile loads

Soil-reinforcement interaction consists of three factors including frictional resistance, shear strength of the soil and passive resistance. In the ordinary polymeric strap (PS) reinforcement, only frictional resistance contributes to pullout resistance. In this study, in order to develop passive resistance in the soil, a number of angles as transversal elements were attached to PS reinforcement, which is called bearing polymeric strap (BPS). The post-cyclic pullout behaviour of the BPS is evaluated using a large-scale pullout apparatus adopting multistage pullout (MSP) test and one-stage pullout (OSP) test procedures. The results show that a spacing-to-high ratio of angles equal to 3.33 gives the maximum pullout resistance. MSP tests were performed on the BPS with an optimum arrangement to evaluate the influence of various factors including cyclic tensile load amplitude, load frequency and number of load cycles, and also the influence of vertical effective stress on the pullout resistance and the peak apparent coefficient of friction mobilized at the soil-BPS interface. Moreover, for BPS system with a single isolated transverse member, the bearing capacity factor Nq was calculated using equations based on three failure modes and it was found that the Nq calculated in the punching shear failure mode makes the best prediction.

Revealing the stress corrosion cracking initiation mechanism of alloy 718 prepared by laser powder bed fusion assessed by microcapillary method

Stress corrosion cracking (SCC) behaviour of L-PBF processed alloy 718 in chloride-containing solution was revealed, utilizing the microcapillary method under constant tensile loading. Results were compared with conventionally produced counterparts. Passive layer resistance was compared quantitatively by implementing electrochemical polarization experiments, in as-received and under tensile loading states. Superior corrosion and SCC resistance of L-PBF specimens under tensile loading were identified. Submicron cracks were initiated adjacent to the subgrain boundaries and the underlying mechanisms were elucidated as the synergistic effect of various microstructural factors. Data availabilityThe raw data with the findings of this article cannot be shared since there is ongoing research on this topic.

Examining the effect of Debris Flow on Oil and Gas Pipelines Using Numerical Analysis

This article examines the impact of debris flow on semi-exposed pipelines to determine the plastic deformation and stresses by considering pipe-debris flow interaction. A 3-D finite element approach was adopted to study the mechanical behavior of pipelines subjected to debris flow. Integration of pipeline property (thickness) with debris flow intensity (impact pressure and angle) was also considered in a finite element numerical model for semi-exposed. The analysis showed that the impact angle between 35° and 75° with an impact pressure of 200 kPa and 250 kPa significantly affected the stability and integrity of the pipeline. There was a slight impact of wall thickness on the stability of the pipeline due to the passive soil resistance. Maximum plastic deformation of 124 mm was encountered in the case of 35° impact angle, which was 3% more than the deformation observed at 20° impact angle. Moreover, large distribution of von mises stresses was observed, as 1390 Mpa, 1450 Mpa, 1440 Mpa, and 1440 Mpa for impact angles of 20°, 35°, 75°, and 90° in the impacted zone of the pipeline in each set of analysis. Shear failure of the pipeline was observed during the analysis as von misses’ stresses were more than the yield stress (520 Mpa) of the pipeline. The developed model in this study can be utilized for further research and will be a basis for designing pipelines crossing through mountainous regions.

Passive resistance to health information technology implementation: the case of electronic medication management system

ABSTRACT Purpose – This study attempts to understand the factors that influence clinician resistance to the implementation of health information technology in a mandatory setting. Design/methodology/approach – A survey study was conducted with 202 clinicians regarding their perceptions of the implementation of electronic medication management systems (eMMS) in an Australian hospital. The data was collected during the initial roll-out of eMMS for model validation and quantitative analysis. Findings – The overall results indicated that performance expectancy, switching costs, and facilitating conditions are direct predictors of clinician resistance, whereas effort expectancy and social influence showed indirect effects on clinician resistance through performance expectancy or switching costs. Theoretical implications – The study is among the first study that investigates passive clinician resistance to the implementation of health information technology in a health organisation. This study also focused on opposition behaviour among under-examined degrees of resistance. Practical implications – This study provides some insights to the hospital management on how to mitigate clinician resistance in the implementation of health information technology. Research limitations/Future directions – Other types of clinician resistance, such as postponement and rejection, are not examined in this study. Future research on postponement behaviour and rejection behaviour is needed to have a more comprehensive view of clinician resistance.

A transcriptomic-guided strategy used in identification of a wheat rust pathogen target and modification of the target enhanced host resistance to rust pathogens.

Transcriptional reprogramming is an essential feature of plant immunity and is governed by transcription factors (TFs) and co-regulatory proteins associated with discrete transcriptional complexes. On the other hand, effector proteins from pathogens have been shown to hijack these vast repertoires of plant TFs. Our current knowledge of host genes' role (including TFs) involved in pathogen colonization is based on research employing model plants such as Arabidopsis and rice with minimal efforts in wheat rust interactions. In this study, we begun the research by identifying wheat genes that benefit rust pathogens during infection and editing those genes to provide wheat with passive resistance to rust. We identified the wheat MYC4 transcription factor (TF) located on chromosome 1B (TaMYC4-1B) as a rust pathogen target. The gene was upregulated only in susceptible lines in the presence of the pathogens. Down-regulation of TaMYC4-1B using barley stripe mosaic virus-induced gene silencing (BSMV-VIGS) in the susceptible cultivar Chinese Spring enhanced its resistance to the stem rust pathogen. Knockout of the TaMYC4-1BL in Cadenza rendered new resistance to races of stem, leaf, and stripe rust pathogens. We developed new germplasm in wheat via modifications of the wheat TaMYC4−1BL transcription factor.

Socrates and Satyagraha in South Africa: A Critical Study of M.K. Gandhi’s Translation of Plato’s Apology

M.K. Gandhi published a translation of Plato’s Apology in Gujarati as Ek Satyavir ni Katha in his self-edited newspaper Indian Opinion in six instalments. The last instalment was published on 9 May 1908 (CWMG vol.8: 217). This translation played a vital part in Gandhi’s first Satyagraha in South Africa. Gandhi’s translation is ideologically loaded and provides counter-texts that both challenged imperial domination and provided themes and forms for the development of postcolonial debates and new senses of identity. In addition to his politics, Gandhi encounters several issues as a translator, especially with cultural equivalents, translating rhetoric speech and references to Greek culture, society and gods. This paper compares target and source texts and also explores the impact of this translation on the Gujarati community in South Africa and on Gandhi. Keywords: Gandhi, Socrates, Passive Resistance, Translation Studies, Paratext, Refraction.

Mobilization mechanism and calculation method of embedded chain axial resistance in sand

For the mooring chain embedded in seabed, the axial resistance greatly influences the chain load transfer. For calculating chain axial resistance, effective width parameter Et is adopted to reflect its characteristic dimension. However, the mobilization mechanism of chain axial resistance in sand is unrevealed at present. In this paper, the large deformation simulation based on a Coupled Eulerian-Lagrangian (CEL) approach was carried out to reveal the chain-sand axial interaction mechanism. Then, a calculation method based on the mechanism was proposed to divide the chain axial resistance into three parts, i.e., sand-sand friction, chain-sand friction and passive resistance. A series of chain axial loading tests were conducted and the results were taken as the comparative data. Compared with the test data, a reduction factor α was introduced to modify the chain passive resistance due to stress release of the front chain link. Large deformation simulation result shows that soil near the chain straight bar moves with chain, but the soil in front of the link has outward movement because of chain end resistance. By introducing a reduction factor, the proposed method can be adopted for calculating the chain axial resistance. At last, the resistance contribution and mobilization order were assessed.