bluuebunny/crossref_metadata_2025 huggingface dataset:
Manufacturability analysis of composite component and its evaluation methodology
Authors: Tang Yingwei , Liu Wenjian , Li Huimin , Zhang Boming , Cong Jingjie
Published: January 2013

Manufacturability calculation of product’s design proposal often plays a vital role in many engineering applications, which is critical to achieve reduced time to market, high quality, and low cost. A methodology for the manufacturability evaluation of composite material components during preliminary stage of design is introduced and applied for the thermosetting composite laminated components produced by autoclave process in this article. The proposed methodology relies on the consideration that the component’s quality is a decisive index in the manufacturability evaluation of composite products. First, according to the analysis of composite product manufacturing processes, the concept of composite product manufacturability was proposed in this article. Second, the knowledge-based manufacturability evaluation flow is acquired based on the hierarchical indices setup of composite product manufacturability. Then, we mainly studied assessment model of composite product quality controllability: the quality controllability of composite product and its influencing factors were discussed. In addition, the quality controllability assessment model proposed was carried out step by step through the characteristic of multi-procedure in the production of composite product. In the end, an example of composite laminate component was provided to demonstrate the proposed model for evaluating the manufacturability.
Is the Use of Short-Term Incentives Good Organization Strategy?
Authors: Wynter-Palmer Jennifer E.
Published: January 2013

This article is based on research conducted on Jamaica’s hotel industry. The study sought to determine if there are any advantages to both employers and employees in use of short-term incentives in that industry. Using theories of motivation and the concepts governing incentive compensation to construct a theoretical framework, the article sought to make the link between short-term incentives, motivation and employee productivity. The debate by both academicians and human resource practitioners is about the right types as well as the right mix of workplace motivators. It is acknowledged that there are strong arguments on all sides. This article seeks to add to the academic debate by advancing that what is critical is that (a) the need for employee motivation should not be viewed as optional but must be fully appreciated, planned and implemented thoughtfully by employers; and (b) the motivational processes used will be influenced by the thinking of an organization’s leadership team as well as the culture of the organization. It is posited for this discussion that where organizations are on a quest to improve workforce productivity, their employees need to be motivated by a combination of intrinsic and extrinsic rewards. In turn, the right types and levels of motivation will lead to employees performing at the desired levels.
Employees’ Attitudes Toward Equity-Based Compensation
Authors: (Meni) Abudy Menachem , Shust Efrat
Published: January 2013

This article presents a field study that examines the subjective value of equity-based compensation and investigates the relationship between attitude toward risk and compensation preferences. The participants in the field survey received equity-based compensation in the past but lack financial education background. We find that the respondents exhibit difficulty in estimating the value of employee stock options, which usually results in a subjective value that is lower than the objective value (calculated using the Black–Scholes model). Additional findings demonstrate the presence of behavioral biases such as priming and mental anchoring. Finally, we document an absence of transitivity in the preferences of 10% of the respondents.
Public–Private Pay Comparisons
Authors: Lee Robert E. , Thompson Andrew M.
Published: January 2013

As state and local governments attempt to manage fiscal stress created by the Great Recession, the level of compensation received by public sector workers has become an increasingly debated policy issue. A significant amount of research exists that addresses national public sector compensation trends, but relatively few state-level studies have been performed. This analysis provides a preliminary analysis of public and private sector compensation in Florida. Using data from the U.S. Bureau of Labor Statistics and the U.S. Census Bureau, sector-level comparisons are made between public and private sector workers within the state with regard to compensation, age and education. This sector-level comparison is then supplemented by an occupational analysis of career fields found in both sectors. The sector-level analysis suggests public sector workers in Florida are, on average, not only better compensated than those in the private sector in aggregate but are also considerably more educated and older. The occupational analysis suggests that public sector workers in Florida are in general less well-compensated than private sector workers employed in the same field, even when older and more highly educated on average.
Changing the Compensation Conversation and the Growing Utility of Noncash Rewards and Recognition
Authors: Van Dyke Melissa , Ryan Mike
Published: January 2013

In the aftermath of the great recession, progressive HR executives represent a key partner to executives looking to do more with less. As the need for increasingly agile and cost- effective reward structures expand in strategic importance, top business leaders and consultants are turning more and more to non-cash rewards and recognition. Research shows that top-performing organizations are using travel, merchandise and gift cards to augment current reward structures and impact near-term success. And they are doing so with great success. By following eight basic events in the design and implementation of non-cash reward and recognition programs, all organizations can build a cost-effective reward portfolio that captures key talent and, most importantly, business results.
A study on the dynamic six-component force measurement with wind loads
Authors: Gao Yifei , Ren Zongjin , Jia Zhenyuan , Liu Wei
Published: January 2013

Dynamic six-component force measurement is of great significance in the area of aerodynamics. Although a large number of previous experiments had been carried out to study the static characteristics of wind tunnel balance, these test methods are difficult to apply to the dynamic measurement. In this article, a new mechanical device is developed to simulate the hatch open motion with wind loads, and then the dynamic loads is measured by the novel piezoelectric balance. Owing to the dynamic motion characteristics of nonlinearity, nonstationarity, and internal coupling, an effective control system, measuring principle and signal processing method have been proposed. A combined wavelet analysis and EMD adaptive algorithm with multi-sensor data fusion method is studied to process the complicated force signal. In addition, the inertial force of the hatch is eliminated and a force curve changing with angle and time has been obtained. Furthermore, dynamic experimental results demonstrate that the mechanical system and signal processing method can effectively control the hatch open motion and extract the feature of six-component force.
Studies on the wobble mode stability of a three-wheeled vehicle
Authors: Karanam Venkata M , Ghosal Ashitava
Published: January 2013

A wobble instability is one of the major problems of a three-wheeled vehicle commonly used in India, and these instabilities are of great interest to industry and academia. In this paper, we studied this instability using a multi-body dynamic model and with experiments conducted on a prototype three-wheeled vehicle on a test track. The multi-body dynamic model of a three-wheeled vehicle is developed using the commercial software ADAMS/Car. In an initial model, all components including main structures such as the frame, the steering column and the rear forks are assumed to be rigid bodies. A linear eigenvalue analysis, which is carried out at different speeds, reveals a mode that has predominantly a steering oscillation, also called a wobble mode, with a frequency of around 5–6 Hz. The analysis results shows that the damping of this mode is low but positive up to the maximum speed of the three-wheeled vehicle. However, the experimental study shows that the mode is unstable at speeds below 8.33 m/s. To predict and study this instability in detail, a more refined model of the three-wheeled vehicle, with flexibilities of three important bodies, was constructed in ADAMS/Car. With flexible bodies, three modes of a steering oscillation were observed. Two of these are well damped and the other is lightly damped with negative damping at lower speeds. Simulation results with flexibility incorporated show a good match with the instability observed in the experimental studies. Further, we investigated the effect of each flexible body and found that the flexibility of the steering column is the major contributor for wobble instability and is similar to the wheel shimmy problem in aircraft.
Unilateral Hallux Valgus
Authors: Young Ki Won , Park Young Uk , Kim Jin Su , Jegal Hyuk , Lee Kyung Tai
Published: January 2013

Background:

This study was undertaken to determine whether unilateral hallux valgus progresses unilaterally and to evaluate the demographics, etiologies, and radiographic findings associated with symptomatic unilateral hallux valgus deformities.

Methods:

Patients treated for hallux valgus between January 2004 and December 2008 were identified, and of these, 33 patients with unilateral deformities were enrolled. Progression of deformities in normal feet were evaluated at last follow-up visit, and the clinical information and radiographic measurements of those with a deformed normal foot or an unchanged normal foot were compared.

Results:

Thirty-three patients (3.4%) had a unilateral hallux valgus deformity on preoperative radiographs. The mean length of follow up was 4.7 years (range, 2.4-11). Twenty-four cases had no deformity of the normal foot at last follow-up (the unchanged group), but 15 cases had developed hallux valgus deformity (the deformed group). No significant intergroup differences were found in terms of metatarsus adductus angle ( P = .412), Meary angle ( P = .771), talocalcaneal angle ( P = 1.000), or calcaneal pitch angle ( P = .267). However, members of the deformed group were significantly younger at disease onset ( P = .045), exhibited a curved first metatarsal head ( P = .046), and had a larger initial hallux valgus angle ( P < .001).

Conclusions:

The frequency of bilateral symptomatic hallux valgus was found to be over 97.3%, and significant differences were found between the deformed and unchanged groups in terms of age of onset, metatarsal head shape, and hallux valgus angle.

Level of Evidence:

Level III, case-control study.
Understanding and researching complexity with Qualitative Comparative Analysis: Evaluating transportation infrastructure projects
Authors: Verweij Stefan , Gerrits Lasse M.
Published: January 2013

This article proposes a complexity-informed framework for evaluating transportation infrastructure projects. The article does this through four steps. First, the properties of infrastructure development projects are discussed. This leads to the conclusion that the specific locality or contextualization of a given project is important for explaining the outcome. Hence, there is a need for an ontology and epistemology that addresses the importance of this contextualization. The second step concerns the development of the prerequisites for a methodological framework that follows from this epistemology and ontology. The third step is the assessment of common infrastructure evaluation methods against these prerequisites. This leads to the conclusion that a comparative case-based approach is the most suitable way to study the relationship between context and outcomes in projects. A framework based on Qualitative Comparative Analysis (QCA) is presented in the fourth step. The article concludes with a discussion of the further development of QCA.
Monitoring, evaluation and performance management in South Asia: The challenge of building capacity
Authors: Mehrotra Santosh
Published: January 2013

The article reviews the state of M&E in South Asia, and makes a case for building capacity in the field, without which the discipline will remain underdeveloped, and accountability for government spending not improve. We suggest that almost none of the South Asian countries have yet managed to develop an M&E ‘system’, though all have mechanisms in place. The article discusses the MIS and evaluation systems, tools in use by governments in South Asia, budgets for evaluation, and the role of civil society organizations. It highlights two cases in South Asia (India and Sri Lanka) where the concept of Performance Management has gathered momentum, even though outcome budgeting has barely taken off in any country of the sub-region. It examines plans for improving implementation of evaluation, but finds many areas suffering from capacity weaknesses. The article closes by recommending ways to address the capacity weaknesses.
Reflections on private-sector evaluation in the European Bank for Reconstruction and Development: 1991–2010
Authors: Korfker Fredrik
Published: January 2013

This article describes private-sector evaluation in the European Bank for Reconstruction and Development (EBRD) from the beginning of the institution in 1991 until the end of 2010. It shows the way of undertaking ex-post project evaluation that was adopted by the EBRD’s Board during that period, against the background of a region that experienced severe ups and downs as a result of different financial crises. It describes how the EBRD’s theory-based evaluation system, anchored in a comprehensive evaluation policy, evolved over time, being reviewed and amended approximately every five years. At the heart of this evolving system was a progressively more independent evaluation function that followed the good practice standards of the Evaluation Cooperation Group (ECG), the working group for cooperation among multilateral development bank (MDB) evaluators. The article pictures the dual objective of evaluation through concentrating on generating lessons and being a Board accountability tool. It poses the question, ‘who evaluates the evaluators?’ and shows the importance of applying an established ECG peer-review system of evaluation functions in MDBs.
A systematic review and meta-analysis of propionyl-l-carnitine effects on exercise performance in patients with claudication
Authors: Brass Eric P , Koster David , Hiatt William R , Amato Antonino
Published: January 2013

Propionyl-l-carnitine (PLC) may improve exercise performance in patients with peripheral artery disease, but results from clinical trials have been inconsistent. The safety and efficacy of PLC for treatment of claudication was evaluated by a systematic review and meta-analysis of clinical trials for which data were available through September 2010. Eighty-five studies were identified, of which 13 were randomized controlled trials. Owing to database availability for the six phase III studies carried out with PLC (1 g orally, twice daily), a patient-level meta-analysis was conducted as the primary analysis. Treadmill performance data from these six studies were harmonized to peak walking distance (PWD) on a 7% grade at a speed of 3 km/hour. PLC ( n = 440) was associated with a net 16 meter improvement (95% CI, 8–20 meters) in PWD as compared with placebo ( n = 427) in the primary analysis ( p = 0.002). The effect of PLC was similar in subpopulations defined using clinical and demographic variables, with possible enhanced benefit in patients engaged in an exercise program or enrolled at study sites in Russia. The systematic review of the effect of PLCs on claudication identified seven additional randomized controlled trials for a total of 13 trials, which included 681 patients on placebo and 672 on PLC. This meta-analysis confirmed a 45 meter net improvement on PLC using a random-effects model. In conclusion, oral PLC is associated with a statistically significant increase in PWD in patients with claudication, which may be clinically relevant.
The Dynamic Aging Mind
Authors: Park Denise C. , McDonough Ian M.
Published: January 2013

The conception of the aging mind that emerged from behavioral and structural imaging studies portrayed the mind as a victim of passive deterioration and decline with age, with a few domains of preserved function. The advent of functional neuroimaging has demonstrated that the aging brain is an adaptive and plastic structure that responds dynamically to cognitive challenge and structural deterioration—thus, fundamentally changing views of cognitive aging. In addition, a neural theory of the aging mind based on behavioral data—the dedifferentiation view of cognitive aging—was largely confirmed when neuroimaging technology became available to test it. We argue that functional neuroimaging has advanced cognitive aging theories by creating a stronger emphasis on compensatory mechanisms related to brain plasticity and potential reorganization as evidenced by the resurgence of interest and research in cognitive training research designed to improve cognition through enhancement of neural structures or reorganization of functional circuitry.
How fMRI Can Inform Cognitive Theories
Authors: Mather Mara , Cacioppo John T. , Kanwisher Nancy
Published: January 2013

How can functional magnetic resonance imaging (fMRI) advance cognitive theory? Some have argued that fMRI can do little beyond localizing brain regions that carry out certain cognitive functions (and may not even be able to do that). However, in this article, we argue that fMRI can inform theories of cognition by helping to answer at least four distinct kinds of questions. Which mental functions are performed in brain regions specialized for just that function (and which are performed in more general-purpose brain machinery)? When fMRI markers of a particular Mental Process X are found, is Mental Process X engaged when people perform Task Y? How distinct are the representations of different stimulus classes? Do specific pairs of tasks engage common or distinct processing mechanisms? Thus, fMRI data can be used to address theoretical debates that have nothing to do with where in the brain a particular process is carried out.
Surgical site infection: the principles and practice of surveillance. Part 1: Key concepts in the methodology of SSI surveillance
Authors: Wilson Jennie
Published: January 2013

urgical site infections (SSI) account for a major proportion of healthcare associated infections (HCAI) yet many hospitals capture little data on the risk of SSI in patients undergoing surgery and therefore have little assurance about the quality of infection prevention in their operating departments. This paper is the first part of a two part series that will examine the principles and practice of surveillance of SSI. Part 2 will examine the analysis of SSI data and the use of the results to change practice. This paper reviews the principles that underpin SSI surveillance methodology, key concepts that affect the accuracy of data capture systems and strategies for addressing them, including risk factors and active case finding systems to ensure detection of SSI, including those that develop after discharge from hospital.
Off-licence prescribing and regulation in psychiatry: current challenges require a new model of governance
Authors: Sugarman Philip , Mitchell Amy , Frogley Catherine , Dickens Geoffrey L , Picchioni Marco
Published: January 2013

The growing worldwide use of pharmaceuticals is managed in some countries by a regulatory system which sharply divides legal use into licensed and unlicensed categories. We examine how for the range of psychotropics this simultaneously restricts the possible benefits to patients, prescribers and producers in some domains, while failing to manage the risks in others. A more flexible system, which shares at an earlier stage experience and evidence on benefits and risks in patients, previously marginalized on the grounds of age, diagnosis or comorbidity, would aid the development of safer, more effective ‘real-world prescribing’. Practical recommendations are made for a new model of research and prescribing governance, to enable more effective repurposing of these treatments.
Peridural Anesthesia or Ultrasound-Guided Continuous 3-in-1 Block
Authors: Luger Thomas J. , Kammerlander Christian , Benz Maureen , Luger Markus F. , Garoscio Ivo
Published: January 2013

Purpose:

The aim of our study was to investigate the clinical relevance of preoperative acute pain management and cardiovascular stability by ultrasound-guided continuous 3-in-1 nerve block in very elderly patients with hip fracture when compared to epidural anesthesia (PDA).

Methods:

To study the analgesic effect, we enrolled 37 very elderly patients with hip fractures, of whom 3 patients with dementia had to be excluded. Thus, 34 patients were randomized to 1 of the 3 groups: group A (ultrasound-guided continuous 3-in-1 block, bupivacaine; n = 10, dropout rate: 0), group B (PDA, bupivacaine; n = 14, dropout rate: 8), and group C (systemic pain therapy, piritramide/paracetamol; n = 10, dropout rate: 0). Pain intensity was assessed preoperatively and up to 24 hours postoperatively using a visual analog scale, verbal rating scale, analgesic consumption, scale of well-being, and cardiocirculatory parameters (eg, serum troponin T).

Results:

Our data show that in the preoperative period both regional anesthesia (RA) procedures (analgesia responders after 1 hour: 86.7% and 100%; P = .001) were superior to systemic analgesia (analgesia responders: 46.7%), and the rescue medication requirement in the 2 RA groups was significantly lower ( P = .02). Serum troponin T level increased only in the systemic analgesia group ( P = .04). In the emergency department, the disadvantage of PDA in geriatric patients with hip fracture was the fact that procedures were more complex, resulting in a high dropout rate (57.1%). The use of PDA has to be critically discussed for ethical concerns.

Conclusion:

In the specific situation of acute hospital admission, the ultrasound-guided continuous 3-in-1 block appears to be indicated as a stress-free means of providing adequate preoperative pain relief in very elderly patients with hip fracture. However, these findings should be corroborated by studies involving larger numbers of patients.
Influence of Ti/N ratio on simulated CGHAZ microstructure and toughness in X70 steels
Authors: Zhu Z X , Marimuthu M , Kuzmikova L , Li H J , Barbaro F , Zheng L , Bai M Z , Jones C
Published: January 2013

Three API 5L X70 steels with different Ti and N contents and otherwise identical chemistry were selected to investigate the effect of Ti/N ratio on the toughness in coarse grained heat affected zone (CGHAZ). A Gleeble 3500 thermomechanical simulator was used to simulate the thermal profile of CGHAZ of double submerged arc welding process. The microstructure was examined by optical microscopy. Statistics of CGHAZ grain coarsening were compiled by measuring the prior austenite grain size. Toughness of the simulated CGHAZ regions was evaluated by Charpy V-notch testing at −20 and −40°C. Morphology of the impact fracture surface was investigated using SEM. Steel B with Ti/N ratio of 3·22 (slightly below stoichiometric) showed slightly higher toughness in the simulated CGHAZ due to higher volume fraction of austenite grains less than 80 μm in diameter.
Solidification crack and morphology for laser weave welding of Al 5J32 alloy
Authors: Kim C , Kang M , Kang N
Published: January 2013

Linear and weaving laser welding were performed on a self-restraint tapered specimen of an Al 5J32 alloy. Linear welding produced columnar grains along the fusion line and equiaxed grains along the centreline. Solidification crack developed along the centreline having equiaxed grains. For laser weave weld, the solidification crack disappeared at a weaving frequency of 5 Hz. However, as the weaving frequency increased further, the length of the columnar grains inside the weaving trajectory curve became smaller than that outside the curve, and the equiaxed grains did not necessarily grow along the centreline of the weld. Therefore, the wide equiaxed grains deviated from the transverse weaving profile and a near linear solidification crack developed. The simulated morphology using solidification rate and temperature gradient correlated well with the solidification morphology obtained from the experiments. The limiting boundary condition for differentiating between the columnar and the equiaxed microstructures in the alloy was G = 3·5 R.
Improved measurement of resistance and calculation of arc power in fusion welding
Authors: Wong Y-R , Ling S-F
Published: January 2013

We reported a new method based on the input electrical impedance of a welding system to measure the resistance of the welding system for the arc power calculation in fusion welding. This impedance can be obtained by dividing the measured voltage to current in their analytic form. Two time recorded waveforms, namely, resistance and reactance of impedance, are therefore calculated. Theoretically, the resistance used for arc power calculation is obtained by dividing measured voltage to current directly without considering the influence of inductance. Through experimental studies, we confirm that the error of arc power calculation incurred by the influence of inductance can range from 2 to 10% depending on the welding voltage and current setting. Since the proposed method can obtain the resistance of the welding system without the influence of inductance, it is a better approach as compared with the current method to obtain the accurate resistance and then arc power.
Surface deposits in laser brazing
Authors: Klocke F , Frank S
Published: January 2013

Laser brazing is a joining technology which is typically employed in areas with particularly high quality requirements, e.g. to create zero gap roof joints in automotive production. These seams have to be leak proof and are situated in an area of the car body which is in direct view of the customer. Hence, seam defects and imperfections are inacceptable and require extensive rework whenever they occur. Resulting high rework costs can be avoided by investigating the causes of these imperfections in order to prevent their formation. One type of imperfection which may occur during the laser brazing of galvanised steel are dark deposits on the seam surface. This paper examines the mechanisms leading to the formation of this type of imperfection. Results on the properties of surface deposits are presented along with conclusions regarding the systematic reasons behind their formation. Finally, strategies for preventing the occurrence of surface deposits are recommended.
Temperature and force response characteristics of friction stir welding on Invar 36 alloy
Authors: Zhao Y , Wu A P , Ren J L , Sato Y S , Kokawa H , Miyake M , Yan D Y
Published: January 2013

The temperature and force response during friction stir welding of Invar 36 alloy were investigated by experimental measurement and numerical simulation. The effect of welding parameters was studied. The temperature and force characteristics were roughly discussed. It is indicated that an elevation rotational speed results in increasing temperature and decreasing axial force, whereas rotational speed has no obvious influence on the longitudinal force. An elevation travelling speed produces increasing axial force and longitudinal force, and a decreased trend of temperature out of stir zone centre. Friction stir welding of Invar 36 alloy produced relatively high peak temperatures, high axial and longitudinal forces, and a narrow temperature distribution compared with those of the other reported high melting temperature materials.
Hybrid modelling of 7449-T7 aluminium alloy friction stir welded joints
Authors: Wang H , Colegrove P A , dos Santos J
Published: January 2013

Many finite element models use adjustable parameters that control the heat loss to the backing bar, as well as the heat input to the weld. In this paper, we describe a method for determining these parameters with a hybrid artificial neural network (ANN) coupled thermal flow process model of the friction stir welding process. The method successfully determined temperature dependent boundary condition parameters for a series of friction stir welds in 3·2 mm thick 7449 aluminium alloy. The success of the technique depended on the method used to input thermal data into the ANN and the ANN topology. Using this technique to obtain the adjustable parameters of a model is more efficient than the conventional trial and error approach, especially where complex boundary conditions are implemented.
Development of spot weld failure parameters for full vehicle crash modelling
Authors: Yang Y P , Gould J , Peterson W , Orth F , Zelenak P , Al-Fakir W
Published: January 2013

A cost and time effective process was developed to create spot weld failure parameters for crash models implemented in LS-DYNA. The process includes a design of experiment (DOE) approach for coordinating data collection, welding and testing, finite element modelling, statistical analysis, validation, and implementation. The DOE approach was used to coordinate testing of a reduced set of samples over a large range of material strengths and gauges. This testing included cross-tension, lap shea, and coach peel type evaluations. Computer models for each metal combination and sample geometry were developed to obtain normalised tensile, shear and bending stress at the incidence of weld failure. These normalised loads were then regressed to extend these results to all possible material combinations within the DOE space. These results were then used to estimate the spot weld failure parameters for all the stack-ups of interest. A set of multiweld T-section samples were then welded, physically tested and computer modelled to validate the failure parameters developed from the small single weld tests.
Monitoring torque and traverse force in friction stir welding from input electrical signatures of driving motors
Authors: Mehta M , Chatterjee K , De A
Published: January 2013

Experimental measurements of torque, traverse force and thermal cycles in friction stir welding (FSW) are challenging due to the simultaneous rotational and linear motions of the tool and the deformation of workpiece material around the tool pin. We propose here a methodology to measure the torque and the traverse force by monitoring the current and power transients of the electrical motors that drive the rotational and linear motions of the FSW tool respectively. The measured values of torque and traverse force in FSW of AA 7075-T6 and AA 2524-T351 at different combinations of tool rotational speed and tool shoulder diameter are validated with the corresponding computed results from a well tested numerical model. The proposed method alleviates the need to use expensive torque and force dynamometers, and provides an economical and robust route for indirect measurement of real time torque and traverse force in FSW.
Effect of aluminium content on acicular ferrite formation in low carbon steel weld metals
Authors: Takada A , Terasaki H , Komizo Y
Published: January 2013

This paper describes the effect of Al content on the formation of acicular ferrite in low carbon steel welds. Inclusions and the microstructures of welds with three levels of Al content were analysed. Acicular ferrite was formed in the low and medium Al content samples, but not in the high Al content sample. In the low and medium Al samples, a TiO layer, which encourages acicular ferrite nucleation, was formed around the inclusions. Grain boundary ferrite was formed only in the low Al content sample. Inclusions in the low Al sample were predominantly composed of the amorphous phase, whereas those in the medium Al sample were composed of spinel structures. It was confirmed by electron energy loss spectroscopy analysis that boron existed in the amorphous phase. The formation of the amorphous phase enhances grain boundary transformation by absorbing boron, which stabilises austenite grain boundary, whereas the formation of spinel structures enhances intragranular transformation by suppressing the boron absorption.
Joining of aluminium sheets by combined solid state and TLP bonding processes
Authors: Lee E , Quintana O , Indacochea J E , Wojarski L , Pfeiffer J , Tillmann W
Published: January 2013

Our effort is to develop an innovative process to join Al sheets at moderate temperatures (200–300°C) by accumulative roll bonding (ARB) combined with transient liquid phase bonding utilising Ga. Solid state joining of Al is limited by the surface Al2O3 that hampers the Al atom diffusion despite the intimate contact between the metal sheets. Mechanical brushing of the Al2O3 improves bonding. Our approach uses ARB to break the brittle Al2O3 by roll bonding two sheets. Strips of 1100-Al were cut, cleaned coated with a thin film of Ga and then preheated before rolling. The Ga coated Al strips roll bonded at 200°C showed greatest strengths, but processing at 300°C resulted in lower strengths with evidence of liquid metal embrittlement. The undamaged Al2O3 prevents liquid Ga from contact with the Al metal.
Challenges and developments in pipeline weldability and mechanical properties
Authors: Liu C , Bhole S D
Published: January 2013

Recent economic and political events have further highlighted the need for new and strategically accessible sources of oil and gas. With the continually increasing demand for oil and gas, the requirement for pipeline steels with higher strength, toughness and weldability has been one of the most important factors driving the development of high strength pipeline steels, particularly with the oil exploration proceeding into arctic and deep sea regions, enhancing the weldability and mechanical properties of the new pipeline steels and weld consumables. Developments in the welding processes for manufacture and field welding are described in terms of process principles, equipment, consumables, weld quality, process economics and further developments. The increasing and changing requirement for weldability and mechanical properties in the heat affected zone and weld metal of pipeline welds are presented along with the reported solutions to the problems.
Study on microtexture of laser welded 5A90 aluminium–lithium alloys using electron backscattered diffraction
Authors: Cui L , Li X Y , He D Y , Chen L , Gong S L
Published: January 2013

The microtexture features of Nd:YAG laser welded joints in 5A90 aluminium–lithium (Al–Li) alloys were examined using electron back scattered diffraction (EBSD). Microtexture was determined by means of the grain orientation image maps (OIM), pole figures (PF), misorientation angles and orientation distribution function (ODF) of the weld metal (WM), heat affected zone (HAZ) and unaffected base metal (BM) of the welded joint. The results show that there is a change of microtexture in the WM and HAZ of the welded joint in terms of the component and intensity of the texture. The HAZ of the welded joint inherits the texture characteristics of the BM, whereas the welding heat input has an important influence on the component C {112}<111>. The WM of the welded joint is composed of predominantly equiaxed grains with a random microtexture.
Finite element simulation of butt welded 2·25Cr–1·6W steel pipe incorporating bainite phase transformation
Authors: Xu M J , Lu H , Yu C , Xu J J , Chen J M
Published: January 2013

This article presents a newly developed global optimisation method for the finite element simulation of welding process considering bainite transformation. In this method, the pattern search algorithm was applied to determine kinetic parameters in Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation during a continuous cooling process. Meanwhile, the JMAK equation was modified into an explicit form as a function of welding temperature field to improve calculation efficiency in the optimisation process. This methodology improves the accuracy as calculating the temperature dependent volume fraction of bainite transformation in finite element simulation. The calculated welding residual stresses considering phase transformation effects exhibited better agreement with the measured results than those calculated without phase transformation. The influences of variable cooling rates on welding residual stresses were also investigated.
Strain arrest during isothermal uniaxial deformations of nickel–titanium shape memory alloys and rate independent phase diagrams
Authors: Russalian V R , Bhattacharyya A
Published: January 2013

Strain arrest during uniaxial tests on nickel–titanium polycrystalline wires indicates that beyond a certain stress level at which the microstructure is stable at a given temperature, there is an additional stress needed to sustain pseudoelasticity or reorientation. This additional stress converges asymptotically to a non-zero value with a decrease in deformation rate in case of reorientation as well as pseudoelasticity (in the latter case, the rates are low enough such that isothermal conditions are expected to prevail). The additional stress is sensitive to the value of the overall strain only when there is a change in crystallinity (during pseudoelasticity), but not when the crystallinity does not change (during reorientation). The effect is studied as a function of temperature, and a rate independent stress–temperature phase diagram is proposed. Noting that thermomechanical coupling is a significant feature of the phase transformation in shape memory alloys, a connection is made between the strain arrest results presented in the present paper and the body of work on thermal arrests reported in the literature.
In vitro degradation of AZ31 magnesium alloy coated with hydroxyapatite by sol–gel method
Authors: Tang H , Xin T Z , Luo Y , Wang F P
Published: January 2013

In recent years, magnesium and its alloys have been proposed as a new class of metallic bioabsorbable implant material. Unfortunately, the rapid corrosion rate of magnesium alloys could result in the accumulation of the hydrogen gas and the reduction in the mechanical properties before the healing of bone tissue. It is necessary to develop biocompatible coatings to delay the degradation rate. In the present research, hydroxyapatite coatings are successfully deposited on AZ31 magnesium alloy by sol–gel technique to slow down the degradation and improve the bioactivity. The structure, composition and chemical states of the sol–gel coatings are characterised by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The bonding strength, corrosion behaviours and hydrogen evolution rate of the samples are also studied. The results show that improving the heat treatment temperature can improve the corrosion resistance and the bonding strength between the coating and the substrate. The degradation rate of the samples reduces with improving heat treatment temperature. However, the lowest hydrogen evolution rate is still much higher than the tolerated level of human body. Because of the low melting point of magnesium alloy, it is difficult to reduce the hydrogen evolution rate to the tolerated level of human body only by improving the heat treatment temperature.
Microstructure and corrosion resistance of quenched AISI 4140 steel plasma nitrided and nitrocarburised with and without rare earths
Authors: Tang L N , Yan M F
Published: January 2013

The quenched AISI 4140 steel specimens have been pulse plasma nitrided and nitrocarburised with and without rare earth addition at 560°C for 4 h. The microstructure, microhardness and corrosion resistances of surface layers for the nitrided/nitrocarburised specimens were characterised using optical microscopy, X-ray diffraction, microhardness test, scanning electron microscopy and anodic polarisation tests in 3·5NaCl solution respectively. A significant hardened layer bearing compound and diffusion layer can be obtained when the quenched steel ( α′-Fe) is plasma nitrided/nitrocarburised at this experimental condition, and the compound layer mainly consists of γ′ (N/N,C) and ϵ (N/N,C) phases. The results show that the rare earth addition favours the formation of ϵ (N,C) phase in the surface layer. The compact compound layer with more ϵ (N,C) phase can be obtained by plasma rare earth nitrocarburising of the quenched AISI 4140 steel and has much higher corrosion potential, pitting potential and longer passive region than other compound layers.
Influence of plasma spraying parameters on properties of thermal barrier coatings
Authors: Mrdak M R , Vencl A , Nedeljkovic B D , Stanković M
Published: January 2013

The aim of the present study is to investigate the influence of plasma spay deposition parameters on various properties of two standard thermal barrier coating (TBC) systems deposited on the steel substrate. Two TBC systems were investigated: NiCr–Al–Co–Y2O3/ZrO2–Y2O3 and NiCr–Al–Co–Y2O3/ZrO2–CeO2–Y2O3. Powders were deposited by atmospheric plasma spraying (APS) with two variable parameters. The first variable was substrate temperature (21–23 and 160–180°C), and the second variable was transverse speed of the spraying gun (250 and 500 mm s−1), i.e. coating thickness per one pass of the spraying gun. The quality assessments of TBC systems were made on the base of their microstructure, microhardness, tensile bond strength and thermal cyclic behaviour (thermal insulation properties and thermal cycling fatigue). Analysis of the results showed great influence of plasma spray deposition parameters on the quality of obtained TBCs.
Facile synthesis of monodisperse CdS nanospheres capped with allyl thiourea
Authors: Tang C J , Yang Y X , Zhang D M , Su F J , Zhang Y S
Published: January 2013

Highly monodisperse CdS nanospheres capped with allyl thiourea were synthesised via a facile hydrothermal method without any surfactant. The products were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence and Fourier transform infrared spectra. The results show that CdS nanospheres have the diameters of about 300 nm and are composed of nanoplates. The reaction parameters, such as the concentration of the reagent, the ratio of sulphide to cadmium source and the cadmium salt type that affected the CdS morphology, were investigated systematically. Based on the experiments, the possible formation mechanism for the nanospheres is ascribed to anisotropic growth of the nanoparticles and self-assembly caused by the lowest surface tension. The photoluminescence spectrum of the nanospheres shows about 60 nm blue shift compared with that of bulk CdS.
On tool stirring action in friction stir welding of work hardenable aluminium alloys
Authors: Buffa G , Campanella D , Fratini L
Published: January 2013

In the paper solid state bonding conditions obtained in friction stir welding (FSW) of AA5754-H111 butt joints are analysed, considering the so called zigzag line in the transverse section of the joints. A wide experimental campaign was carried out varying both tool advancing speed and tool rotational one. The effects of the process on the mechanical properties of the joint were highlighted and micro- and macro-observations were used in order to explain the reasons of the enhanced mechanical properties found for the welded material. Numerical results derived from a FEM model previously developed by the authors were utilised to point out the different mechanical and metallurgical behavior of the obtained joints.
Microstructure and dry sliding wear behaviour of titania and alumina–titania coatings
Authors: Vadiraj A , Kamaraj M , Sreenivasan V S
Published: January 2013

The microstructure, hardness and wear properties of atmospheric plasma spray coating of TiO2 and Al2O3–13TiO2 with incremental hydrogen fractions (11·1–23·8%) in primary gas have been investigated in this work. TiO2 coating shows a fine bead-like surface structure, while Al2O3–13TiO2 predominantly exhibits a splat-like morphology. The microstructure shows a slight refinement in the structure for the highest hydrogen content possibly due to the higher specific enthalpy of the plasma plume. Both coatings show the highest hardness for samples coated with the highest hydrogen content possibly due to the refined structure. The roughness shows a mild decreasing trend for TiO2 coating, while the reverse trend is observed for Al2O3–13TiO2 coating. The wear loss and friction coefficient show a flat trend (0·4–0·6) for all the hydrogen contents. The worn tracks show a compacted mixture of ceramic, graphite and metallic particles.
Characterisation of pyrolytic graphite exposed to molten LiCl–KCl salt
Authors: Jagadeesh S , Shankar A Ravi , Mudali U Kamachi , Nowicki A , Raj B
Published: January 2013

Graphite based materials are proposed as one of the candidate materials for metallic fuel reprocessing involving high temperature molten chloride salt environment. Pyrolytic graphite (PyG) was deposited on graphite substrates by thermal chemical vapour deposition using methane gas to enhance their performance in molten chloride environments. The structural features of the PyG deposit were characterised using X-ray diffraction by measuring interlayer spacing, crystallite size and preferred orientation. The present study discusses the corrosion behaviour of PyG in molten LiCl–KCl eutectic salt at 873 K. The PyG samples tested in molten salt for 2000 h in controlled argon atmosphere exhibited negligible weight loss. The as deposited and corrosion tested samples characterised using optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy showed no significant change in surface morphology. The study showed excellent corrosion resistance of PyG in molten salt under inert atmosphere.
Preparation Ce(III) conversion coatings on electrodeposited Zn–Ni alloy and comparison of their corrosion performance and morphology with Cr(VI) conversion coatings
Authors: Hosseini M G , Ghiasvand H A Y , Ashassi-Sorkhabi H
Published: January 2013

Zn–Ni alloy coatings were electroplated on steel after an appropriate pretreatment from tartrate cyanide free alkaline bath. Zn–Ni coatings were obtained with a derivative of imidazol as a brightener agent to form fine grain particles. The Zn–Ni alloy coatings were analysed for phase structure by X-ray diffraction. A cerium based chemical conversion process was developed as an alternative to the chromate process. The cerium conversion coatings improved the corrosion performance. The corrosion behaviour of bare and treated Zn–Ni alloy coatings on steel was evaluated during exposure to 0·5 N NaCl using Tafel polarisation and electrochemical impedance spectroscopy measurements. The morphology and corrosion performance of conversion coatings generated on Zn–Ni alloy coatings in Cr(VI) and Ce(III) treatments were studied and compared. This process may be useful as primer for paints and polymer coatings on steel.
Effect of atmospheric plasma spraying parameters on porosity level of alumina coatings
Authors: Thirumalaikumarasamy D , Shanmugam K , Balasubramanian V
Published: January 2013

Alumina coating was deposited on AZ31B magnesium alloy using atmospheric plasma spraying process by varying parameters such as power, stand-off distance and powder feedrate. The porosity level of alumina coatings were evaluated by the digital image analysis method. An attempt was also made to develop an empirical relationship to predict the porosity level of alumina coatings. Three factors five level central composite rotatable design matrix was used to minimise the number of experimental conditions. Response surface methodology was used to develop the relationship. The developed relationship can be effectively used to predict the porosity level of alumina coatings at 95% confidence level. The results indicate that the input power has the greatest influence on porosity level of the coatings, followed by stand-off distance and powder feedrate.