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The purpose of this paper is to present a new geometric model based on the mathematical morphology paradigm, specialized to provide determinism to the classic morphological operations. The determinism is needed to model dynamic processes that require an order of application, as is the case for designing and manufacturing objects in CAD/CAM environments.

The basic trajectory-based operation is the basis of the proposed morphological specialization. This operation allows the definition of morphological operators that obtain sequentially ordered sets of points from the boundary of the target objects, inexistent determinism in the classical morphological paradigm. From this basic operation, the complete set of morphological operators is redefined, incorporating the concept of boundary and determinism: trajectory-based erosion and dilation, and other morphological filtering operations.

This new morphological framework allows the definition of complex three-dimensional objects, providing arithmetical support to generating machining trajectories, one of the most complex problems currently occurring in CAD/CAM.

The model proposes the integration of the processes of design and manufacture, so that it avoids the problems of accuracy and integrity that present other classic geometric models that divide these processes in two phases. Furthermore, the morphological operative is based on points sets, so the geometric data structures and the operations are intrinsically simple and efficient. Another important value that no excessive computational resources are needed, because only the points in the boundary are processed.

In oil and gas industries, the presence of sand particles in produced oil and natural gas represents a major concern because of the associated erosive wear occurring in various flow passages. Erosion in the tube entrance region of a typical shell and tube heat exchanger is numerically predicted.

The erosion rates are obtained for different flow rates and particle sizes assuming low particle concentration. The erosion prediction is based on using a mathematical model for simulating the fluid velocity field and another model for simulating the motion of solid particles. The fluid velocity (continuous phase) model is based on the solution of the time‐averaged governing equations of 3D turbulent flow while the particle‐tracking model is based on the solution of the governing equation of each particle motion taking into consideration the viscous and gravity forces as well as the effect of particle rebound behavior.

The results show that the location and number of eroded tubes depend mainly on the particle size and velocity magnitude at the header inlet. The rate of erosion depends exponentially on the velocity. The particle size shows negligible effect on the erosion rate at high velocity values and the large‐size particles show less erosion rates compared to the small‐size particles at low values of inlet flow velocities.

In oil and gas industries, the presence of sand particles in produced oil and natural gas represents a major concern because of the associated erosive wear occurring in various flow passages. The results indicate that erosion in shell and tube heat exchanger can be minimized through the control of velocity inlet to the header.

This paper aimed to analyze removed particles from stationary specimen-aluminum (Al-99.92) produced by vibratory cavitation erosion tests in distilled water and glycerol-water mixtures.

The particle morphology which include particle surface topography, size distribution, particle size parameters and particle shape parameters were examined for distilled water and glycerol-water mixtures having different viscosities.

The results showed that the variation of size parameters with viscosity was very similar to the variation of weight loss with viscosity. Both the size parameters and weight losses show a monotonic decrease in going from distilled water to glycerol-water mixtures having viscosity about 10.1 cSt, beyond which the change is very small. On the other hand, the shape parameters were much less sensitive to distinguish between the particles produced in water and glycerol-water mixtures. The mechanism of cavitation erosion is investigated in detail through observations of the removed particles. The particle surfaces topography demonstrated that the mechanism in water and glycerol-water mixtures was fatigue failure.

Cavitation often occurs in almost all machines that handle liquids, especially at high speeds, leading to irreparable damage of the components of these machines. Elucidation of such complex phenomenon demands full characterization of the erosion mechanism and controlling parameters inherent to it, so that cavitation erosion can be prevented or at least be reduced through adequate information and collection of relevant data under different operating conditions. Very few studies have been made to approach the viscosity effect upon cavitation erosion from the particle analysis standpoint. The aim of the present work is to identify the effect of liquid viscosity on the size, shape characteristics of the erosion particles and their morphological features. The prevailed mechanisms of wear and particle generation have been proposed based on the acquired information from particle analysis.

This paper aims to depict the erosion performance of two HVOF-coated micron layers (Colmonoy-88 and Stellite-6) on pump impeller steel (SS-410) by using Taguchi's method. Taguchi's array (L16) was used to optimize the erosion wear (in terms of weight loss) by using four influencing parameters such as rotational speed, solid concentration, average particle size and time which were varied at four different levels.

The experiments were carried out by using a Ducom slurry tester with rotational speed in the range of 750-1,500 rpm, solid concentration of 35-65 per cent by weight, time period of 75-210 min and average particle sizes in the range of < 53 to 250 µm. Bottom Ash with a nominal size range of < 53 to 250 µm was used as erodent. The process parameters were optimized by using Taguchi's method. The ANOVA method was used to validate the results given by Taguchi's method.

The results revealed that the presence of both carbides and borides and the additional presence of Cr in Colmonoy-88 coating enhancing the slurry erosion resistance of Colmonoy-88 coating. Moreover, the chromium and tungsten carbide particles help in increasing the bond strength between the coating and the substrate material. Further, it was also found that the time was the most dominant factor as compared to other factors.

The very less work has been reported on optimization of erosion wear response of Colmonoy-88 and Stellite-6 coatings by using different design of experiment techniques. Further, the erosion wear mechanism of both coatings has been studied by using image j analysis software.

The purpose of this paper is to review the quantum and magnitude of tax avoidance in Nigeria's top seven banks by using recognized tax avoidance proxies of the Generally Accepted Accounting Principles (GAAP) and the International Financial Reporting Standard (IFRS) effective tax rate (ETR) and book-tax gap analysis for the appraisal.

Data for the paper came from the annual reports of the banks between 2011 and 2019. The individual bank’s tax data was analyzed for trends and then consolidated to establish the average percentages and the exact amount of the tax the banks evaded each year and cumulatively over the review period. The data were then matched with analytics of the drivers of tax avoidance in the reconciliation statement to highlight essential tax planning items and strategies being exploited by each bank in the pursuit of aggressive tax avoidance behavior.

F-test comparing the aggregate means (all banks) for tax evasion proxies of ETR and the book-tax gap was conducted at a 95% confidence interval. The results of this paper indicate no significant difference between the means obtained, thus affirming that the same pattern of tax evasion was consistent among the banks for the years reviewed.

The findings of this paper highlight the tax avoidance behavior of the referenced banks, identify weaknesses in the corporate tax planning policy pursued and serve to alert policymakers of the need to strengthen the laws and block loopholes that provide rooms for unrestrained tax avoidance behavior in the banking sector.

The study investigates the long-term erosion of repeat-purchase loyalty among consumers who purchase brands in a one-year base period.

The study uses a five-year consumer panel of continuous reporters. We identify brand buyers in a base year, then calculate the proportion that fail to buy the brand in later years. We analyse the top 20 brands in 10 consumer goods categories.

We find pronounced erosion in repeat-buying over the long-term. The proportion of buyers from a base year that fail to buy in a later year increases steadily over time, from 57% in year 2 to 71.5% by year 5. Moreover, we identify brand and marketing mix factors linked to this over-time customer loss or erosion.

The study provides evidence that consumers’ propensity to buy particular brands changes over a period of years, even though those brands continue to exhibit a stable market share. This evidence provides a different interpretation than the literature to date, which has viewed purchase propensities as fixed.

The study finds that store brands and niche brands exhibit lower levels of erosion in their buyer base; that a broad range is associated with lower erosion, and that high price promotion incidence is associated with lower erosion for manufacturer brands.

Loyalty erosion has been reported before (Ehrenberg, 1988; East and Hammond, 1996) but only over short periods. This study examines the phenomenon over five years, confirms that the rate of erosion does diminish over time, and that it is related to category and brand characteristics, as well as marketing mix decisions.

The purpose of this paper is to develop arguments for a public policy of requiring all large companies to make their tax returns publicly available. It is argued that such a policy would help to check tax avoidance, strengthen public accountability and secure fair competition.

The policy proposal rests on notions of transparency and public accountability.

The paper argues that the proposed policy is feasible.

The paper hopes to stimulate debates about the value of public filing of corporate returns and limits of public accountability.

The paper extends the range of public policies which might be able to check organised tax avoidance.

It is one of the few papers to call for public filings of large company tax returns.

The purpose of this paper is to analyze the mechanism of particle erosion in butterfly valve pipelines under hydraulic transportation conditions. The results will affect the sealing and safety of butterfly valve pipelines and hopefully serve as reference for the anti-erosion design of butterfly valve pipelines.

Through the discrete element method (DEM) simulation that considers the force between particles, the detached eddy simulation (DES) turbulence model based on realizable k-epsilon is used to simulate the solid-liquid two-phase flow-induced erosion condition when the butterfly valve is fully opened. The simulation is verified by building an experimental system correctness. The solid-liquid two-phase flow characteristics, particle distribution and erosion characteristics of the butterfly valve pipeline under transportation conditions are studied.

The addition of particles may enhance the high-speed area behind the valve. It first increases and then decreases with increasing particle size. With increasing particle size, the low-velocity particles change from being uniformly distributed in flow channel to first gathering in the front of the valve and, then, to gathering in lower part of it. Fluid stagnation at the left arc-shaped flange leads to the appearance of two high-speed belts in the channel. With increasing fluid velocity, high-speed belts gradually cover the entire valve surface by focusing on the upper and lower ends, resulting in the overall aggravation of erosion.

Considering the complexity of solid-liquid two-phase flow, this is the first time that the DEM method with added inter-particle forces and the DES turbulence model based on realizable k-epsilon has been used to study the flow characteristics and erosion mechanism of butterfly valves under fully open transportation conditions.

This study aims to investigate the trajectories of sand particles and erosion wear in a hydraulic turbine model.

The Lagrangian-based approach is used to track large numbers of sand particles and determine their impact through the hydro turbine components. The tracking procedure includes the stochastic eddy interaction model and the squeeze film effect. The number of particles, sizes and release positions are conformed to the particle concentration and size distribution. The impact locations, frequency and conditions of impacts are used to estimate the erosion rates and thereby the eroded mass from the distributor vane and the rotor blade and their deteriorated geometry.

The patterns of erosion in the stationary and rotating parts differ significantly and the effect of the initial position of the runner blade is elucidated. The distributor vane is characterized by a widespread of erosion over the pressure side. Typically, the surface beyond the throat and the root and tip junctions are the regions prone to erosion wear. The entry region of the runner blade is subject to a high number of impacts resulting in high erosion rates visible from the forepart of the blade pressure side.

The erosion patterns and geometry deterioration may serve to evaluate the drop in the hydraulic performance and to select the appropriate surface coating to extend the lifetime of the turbomachinery parts and reduce the maintenance cost.

Erosion developments reveal a strong dependence on the blade position against the distributor vane and the particle size and concentration level.

The purpose of this paper is to examine the effects of the trustor's responsibility‐attributions for a trust violation and the trustee's frequency of prior violations on the subsequent erosion of trust in the relationship.

Data were collected from 120 middle‐senior level managers using a two‐part scenario‐based experimental design to test the impact of attributions and frequency of violations. Respondents' levels of trust and distrust were measured pre‐ and post‐violation as well as forgiving and a range of demographic variables.

Results showed that trust eroded (and distrust increased) more when trustors perceived the trustees as not wanting to fulfill the trust‐expectations than when they could not do so. Further, trustors were willing to tolerate a maximum of two violations before trust in the relationship eroded significantly. The results also showed that trustors who were relatively more forgiving were less likely to lose trust in the trustee after a violation, as were younger and less experienced individuals.

Although scenario‐based experiments assess the cognitive states of the respondents rather than actual behaviors, they serve as a valuable first step. By highlighting the two‐step sequence that may underlie the trust erosion process and emphasizing the importance of using an attributional perspective, the paper invites future research on a range of factors such as patterns of violation, degrees of damage, etc. Collectively, they ought to lead to an integrated model of trust erosion.

For practicing managers, the results underscore the importance of maintaining trust by constantly meeting expectations. While they may be forgiven for one‐time mistakes in maintaining trust, they cannot be repeated without severely damaging the trust in the relationship. Also, employees need to be convinced that the erring manager or colleague has done his/her very best to prevent the violation.

This paper addresses an under‐investigated facet of trust research in organizations – erosion of trust – which is especially crucial in light of the growing awareness that most organizational relationships actually start off with high levels of trust rather than low trust. Thus, this study offers insights into maintaining (as opposed to building) trust.