M.M. Abou‐Krisha, F.H. Assaf, M. Khodari and E.M. Elkady
The purpose of this paper is to investigate the corrosion resistance and the electrodeposition behavior of electrodeposited nickel‐cobalt‐iron alloys. Also, to compare the…
Abstract
Purpose
The purpose of this paper is to investigate the corrosion resistance and the electrodeposition behavior of electrodeposited nickel‐cobalt‐iron alloys. Also, to compare the electrodeposition of ternary nickel‐cobalt‐iron alloy from acidic sulfate bath onto a steel substrate with the characteristics of Co‐Fe electrodeposits.
Design/methodology/approach
The investigation of electrodeposition was carried out using cyclic voltammetry and galvanostatic techniques, while potentiodynamic polarization resistance and anodic linear sweep voltammetry techniques were used for corrosion study. The phase structure was characterized by means of X‐ray diffraction analysis. The surface morphology and chemical composition of the deposits were examined by using scanning electron microscopy and atomic absorption spectroscopy, respectively.
Findings
The obtained results revealed that the Ni‐Co‐Fe alloys consisted of a mixture of iron (Fe10.8Ni) and (FeCo) phases. It was found that the obtained Ni‐Co‐Fe alloy exhibited a more‐preferred surface appearance and better corrosion resistance, compared to the Co‐Fe alloy that was electrodeposited under similar conditions.
Practical implications
Ni‐Co‐Fe alloy was successfully electroplated from a sulfate bath. This alloy showed better anticorrosion properties compared to Co‐Fe deposits. The Ni‐Co‐Fe alloy could be used advantageously in industry, e.g. the automotive industry. The coating also has particular interest due to it is ability to exhibit stable magnetic properties.
Originality/value
The paper evaluates the effect of electrodeposition of the ternary alloy on the corrosion behavior of electroplated steel. To date, there has been little research on this issue. It was found that the presence of Ni could increase the corrosion resistance of steel.
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Mortaga Abou-Krisha, Fawzi Assaf, Omar Alduaij, Abdulrahman G Alshammari and Fatma El-Sheref
– The purpose of this study was to compare the electrodeposition behavior and corrosion resistance of ternary and binary alloys.
Abstract
Purpose
The purpose of this study was to compare the electrodeposition behavior and corrosion resistance of ternary and binary alloys.
Design/methodology/approach
Potentiodynamic polarization resistance measurement and anodic linear sweep voltammetry techniques were used for the corrosion study. The surface morphology and chemical composition of the deposits were examined using scanning electron microscopy and atomic absorption spectroscopy, respectively. The phase structure was characterized by X-ray diffraction analysis. Electrodeposition behavior was carried out using cyclic voltammetry and galvanostatic techniques.
Findings
It was found that the obtained ternary alloy exhibited better corrosion resistance and a more-preferred surface appearance compared to the binary alloys that were electrodeposited under similar conditions.
Research limitations/implications
The ternary alloy showed better anticorrosion properties compared to binary deposits that were electroplated successfully from the plating baths. The Zn-Co-Fe alloy could be used advantageously in industry because the ternary alloy exhibits the collective properties of the binary alloys in one alloy via the electrodeposition of Zn-Ni-Co alloy.
Social implications
Increasing the corrosion resistance implies to social economic increases.
Originality/value
To date, the electrodeposition of Zn-Co-Fe alloy was studied in only a small number of articles. It was found that the presence of Co or Fe could provide a useful coating on the steel that would reduce its susceptibility to corrosion attack.
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Yuchen Xiao, Huiyi Tang, Hehe Zhang, Xiaoling Yang, Ling Sun, Yong Xie, Baoan Wu, Baifeng Luan, Weidong Xie and Xinnan Cai
The purpose of this paper is to develop high-performance Au-coated Ag alloy wires (ACAA wires) and demonstrate the effect of Au coating layers on the bonding performance and…
Abstract
Purpose
The purpose of this paper is to develop high-performance Au-coated Ag alloy wires (ACAA wires) and demonstrate the effect of Au coating layers on the bonding performance and oxidation resistance for stable and reliable electronic packaging applications.
Design/methodology/approach
ACAA wire with a diameter of approximately 25 µm and Au layer thickness of approximately 100 nm were prepared by the continuous casting, plating and wire drawing method. The bonding performance of the ACAA wires were studied through bonding on 3,535 chips. The oxidation resistance of ACAA wires and Ag alloy wires (AA wires) were comparatively studied by means of chemical oxidation tests, accelerated life tests and electrochemical tests systematically.
Findings
ACAA wires could form axi-symmetrical spherical free air balls with controllable diameter of 1.5∼2.5 times of the wire diameter after electric flame-off process. The ball shear strength of ACAA wire was higher than that of AA wires. Most importantly, because of the surface Au coating layer, the oxidation resistance of ACAA wires was much enhanced.
Research limitations/implications
ACAA wires with different lengths of heat affected zone were not developed in this study, which limited their application with different loop height requirements.
Practical implications
With higher bonding strength and oxidation resistance, ACAA wires would be a better choice than previous reported AA wire in chip packaging which require high stability and reliability.
Originality/value
This paper provides a kind of novel ACAA wire, which possess the merits of high bonding strength and reliability, and show great potential in electronic packaging applications.
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This chapter provides a survey of alternative methodologies for measuring and comparing productivity and efficiency of airlines, and reviews representative empirical studies. The…
Abstract
This chapter provides a survey of alternative methodologies for measuring and comparing productivity and efficiency of airlines, and reviews representative empirical studies. The survey shows the apparent shift from index procedures and traditional OLS estimation of production and cost functions to stochastic frontier methods and Data Envelopment Analysis (DEA) methods over the past three decades. Most of the airline productivity and efficiency studies over the last decade adopt some variant of DEA methods. Researchers in the 1980s and 1990s were mostly interested in the effects of deregulation and liberalization on airline productivity and efficiency as well as the effects of ownership and governance structure. Since the 2000s, however, studies tend to focus on how business models and management strategies affect the performance of airlines. Environmental efficiency now becomes an important area of airline productivity and efficiency studies, focusing on CO2 emission as a negative or undesirable output. Despite the fact that quality of service is an important aspect of airline business, limited attempts have been made to incorporate quality of service in productivity and efficiency analysis.
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A. George Assaf and Mike G. Tsionas
This paper aims to present several Bayesian specification tests for both in- and out-of-sample situations.
Abstract
Purpose
This paper aims to present several Bayesian specification tests for both in- and out-of-sample situations.
Design/methodology/approach
The authors focus on the Bayesian equivalents of the frequentist approach for testing heteroskedasticity, autocorrelation and functional form specification. For out-of-sample diagnostics, the authors consider several tests to evaluate the predictive ability of the model.
Findings
The authors demonstrate the performance of these tests using an application on the relationship between price and occupancy rate from the hotel industry. For purposes of comparison, the authors also provide evidence from traditional frequentist tests.
Research limitations/implications
There certainly exist other issues and diagnostic tests that are not covered in this paper. The issues that are addressed, however, are critically important and can be applied to most modeling situations.
Originality/value
With the increased use of the Bayesian approach in various modeling contexts, this paper serves as an important guide for diagnostic testing in Bayesian analysis. Diagnostic analysis is essential and should always accompany the estimation of regression models.
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Noel Scott, Brent Moyle, Ana Cláudia Campos, Liubov Skavronskaya and Biqiang Liu
Ghiwa Assaf and Rayan H. Assaad
Project bundling is an innovative practice that groups or bundles several infrastructure projects into a single contract. While project bundling has various benefits, agencies are…
Abstract
Purpose
Project bundling is an innovative practice that groups or bundles several infrastructure projects into a single contract. While project bundling has various benefits, agencies are facing some challenges when bundling their projects, including properly assessing the feasibility (or infeasibility) of project delivery methods (PDMs) of interest. More specifically, project owners face the challenge of properly selecting between traditional and alternative PDMs for their bundled projects. Although some research efforts were devoted to providing guidelines in relation to different aspects related to project bundling, no previous study was conducted to help project owners performing PDMs-related feasibility analysis for bundled projects, which differ from normal, singly delivered projects. To fill this knowledge gap, this paper develops a decision-support tool that assists agencies in deciding whether they should select a traditional or alternative PDM (i.e. whether to go with the Design-Bid-Build (DBB) PDM or not) for their bundled projects.
Design/methodology/approach
An analytical methodology comprised of four main steps was followed in this paper. First, an expert survey was developed and distributed to industry experts to quantify the importance of 25 project bundling objectives. Second, principal component analysis was used to determine the weights for the different project bundling objectives. Third, a series of statistical tests was implemented to identify different feasibility tiers. Fourth, a user-friendly decision-support tool was developed, and its capabilities were demonstrated.
Findings
The results showed that six tiers exist to classify the feasibility (or infeasibility) of traditional PDMs (i.e. the DBB method) for bundled projects. The research outcomes have also reflected that the following five project bundling objectives contribute the most to making traditional PDMs (i.e. the DBB method) more feasible for bundled projects: (1) Having well-defined design features; (2) Requiring prior knowledge or experience with similar project size and scope; (3) Completing the overall project on schedule; (4) Keeping rate of expenditures within cash flow plan; and (5) Acquiring specific legislative, regulatory and jurisdictional requirements early on.
Originality/value
This research adds to the body of knowledge by equipping agencies and project owners with a decision-support system that helps them identify whether traditional or alternative PDMs are more appropriate for the specific objectives of their bundling program(s). By making the right PDM decision, project owners can enhance their bundling practices (especially in relation to the PDM proper selection) and ultimately the performance of their bundled projects.
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Gianmaria Martini, Davide Scotti and Nicola Volta
This chapter considers the productivity of 77 airlines between 1980 and 2013. We do so by estimating a stochastic frontier and decomposing the total factor productivity growth…
Abstract
This chapter considers the productivity of 77 airlines between 1980 and 2013. We do so by estimating a stochastic frontier and decomposing the total factor productivity growth into efficiency, technical and scale efficiency change. Our results show that, on average, airlines increased productivity over the period but that, while efficiency and technical change improved, scale efficiency results indicate that the average airline moved away from the most productive scale size. This was especially so in the two decades after 1980. Comparisons between geographical areas, business models, networks and alliances are also made.
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A. George Assaf and Mike Tsionas
This paper aims to focus on addressing endogeneity using instrument-free methods. The authors discuss some extensions to well-known techniques.
Abstract
Purpose
This paper aims to focus on addressing endogeneity using instrument-free methods. The authors discuss some extensions to well-known techniques.
Design/methodology/approach
This paper discusses some attractive methods to address endogeneity without the need for instruments. The methods are labeled are “harmless” in the sense that instruments are not needed and the distributional assumptions are kept to a minimum or they are replaced by more flexible semi-parametric assumptions.
Findings
Using a hospitality application, the authors provide evidence about the effectiveness of these techniques and provide directions for their implementation.
Research limitations/implications
Finding valid instruments has always been a key challenge for researchers in the field. This paper discusses and introduces methods that free researchers from the need to find instruments.
Originality/value
The paper discusses techniques that are introduced from the first time in the tourism literature.