bluuebunny/crossref_metadata_2025 huggingface dataset:
Tribological behaviors of some novel dimercaptothiadiazole derivatives containing hydroxyl as multifunctional lubricant additives in biodegradable lithium grease
Authors: Chen Huan , Jiang Junhui , Ren Tianhui , Zheng Lei , Zhao Yidong
Published: February 2014

Purpose

– In order to meet the requests of exploring environmental-friendly and multifunctional lubricant additives, some novel dimercaptothiadiazole derivatives containing hydroxyl are prepared and used as antiwear (AW) and extreme-pressure (EP) additives in biodegradable lithium grease. The paper aims to discuss these issues.

Design/methodology/approach

– The tribological performances of the grease samples containing these derivatives are evaluated by using a four-ball tester. X-ray absorption near edge structure (XANES) spectroscopy is used to analyze the chemistry of tribofilms under AW/EP regime, and thermal films are also considered for comparison.

Findings

– The tribological tests show that these derivatives are all effective in reducing wear, especially at lower additive concentrations, but they are basically failed in reducing friction. They are also helpful in improving the EP characteristic of the base grease. The thermal films generated by these derivatives are composed of adsorbed organic sulfide and ferrous sulfate, though for short-chain derivatives, organic sulfide is the only component at 5.0 wt.%. Ferrous sulfide is the main component of the tribofilms formed by these derivatives at various additive concentrations. But for short-chain derivatives, these tribofilms consist of ferrous sulfide and ferrous disulfide at 5.0 wt.%, and the appearance of disulfide suggests that the interfacial temperature between the upper ball and three lower balls under these conditions is considerably low. The EP films generated by short-chain derivatives are all composed of organic sulfide and ferrous sulfide, while for long-chain derivatives, ferrous sulfide is the main component.

Originality/value

– These low-toxic and oil-soluble dimercaptothiadiazole derivatives are effective in improving the tribological characteristic of the biodegradable lithium grease, and these heterocyclic derivatives may be good substitutes for some harmful traditional additives.
Investigation of wear behaviour of thixoformed and conventional gravity cast AlSi8Cu3Fe alloys
Authors: Saklakoglu Nursen , Gencalp Irizalp Simge , Ercayhan Yigit , Birol Yucel
Published: February 2014

Purpose

– In the present work, thixoformed AlSi8Cu3Fe alloy was investigated for its tribological properties. The tribological analysis reveals good sliding wear behaviour for thixoformed alloy due to thixotropic microstructural character. The results are compared with sliding wear behaviour of conventional gravity cast alloy. This paper aims to discuss these subjects.

Design/methodology/approach

– In this study, thixoforming and gravity casting methods are used to produce materials. The ball-on-disc CSM tribometer was used to carry out the tribological tests that were performed under dry sliding conditions, under two different loads of 1N and 5N. Wear tests were performed first on the conventional gravity cast samples and then on the thixoformed counterparts in exactly the same fashion to facilitate a comparison. The microstructural characterizations are performed in optical microscopy, scanning electron microscopy and energy dispersive X-ray spectrometry.

Findings

– Thixoformed samples have better wear resistance than conventional gravity cast samples. The wear performance improves in thixoformed AlSi8Cu3Fe alloy thanks to changing the microstructure. The superiority of the former is attributed to its structural features.

Originality/value

– In this study, the thixoforming of AlSi8Cu3Fe alloy can provide important wear performance in comparison with conventional casting of AlSi8Cu3Fe alloy. This alloy is known to be used widely in automotive industry. Therefore, the alloy is highly exposed to wear and it is thought that thixoforming method can increase the wear resistant.
Preparation and tribological properties of surface-modified calcium borate nanoparticles as additive in lubricating oil
Authors: Huang Ying , Han Sheng , Liu Sizhou , Wang Yuhong , Li Jiusheng
Published: February 2014

Purpose

– To develop a potential substitute for conventional lubricant additive and improve the oil-solubility of nanoparticles, calcium borate nanoparticles modified by an eco-friendly or “green” modifier lauric acid (CBLA) were prepared. The paper aims to discuss these issues.

Design/methodology/approach

– The microstructures of the as-obtained samples were characterized by X-ray power diffraction (XRD) transmission electron microscope (TEM) and infrared spectra (IR). The contact angle was also measured. Tribological properties of CBLA used as additive in base oil were evaluated with a four-ball tribotester and compared with a commercial additive. The worn surface was investigated by polarized microscope (PM) and X-ray photoelectron spectroscopy (XPS).

Findings

– The results indicate that the average size is in the range of 50-100 nm and the surface of calcium borate was altered from hydrophilicity to hydrophobicity. At the same time, the nanoparticles can be dispersed well in the base oil. Tribological results show that CBLA have good antiwear property and friction-reducing property in base oil, and it can be found that during the sliding process, a continuous wear resistance film was formed which containing depositions and the tribochemical reaction products such as B2O3, FeB, Fe2O3 and CaO.

Originality/value

– An eco-friendly or “green” modifier lauric acid could change the surface of calcium borate from hydrophilicity to hydrophobicity, and calcium borate modified by lauric acid has good tribological properties in lubricating oil.
Chemical mechanical polishing of steel substrate using aluminum nanoparticles abrasive slurry
Authors: Peng De-Xing
Published: February 2014

Purpose

– Chemical mechanical polishing (CMP) has attracted much attention recently because of its importance as a nano-scale finishing process for high value-added large components that are used in the aerospace industry. The paper aims to discuss these issues.

Design/methodology/approach

– The characteristics of aluminum nanoparticles slurry including oxidizer, oxidizer contents, abrasive contents, slurry flow rate, and polishing time on aluminum nanoparticles CMP performance, including material removal amount and surface morphology were studied.

Findings

– Experimental results indicate that the CMP performance depends strongly on the oxidizer, oxidizer contents, and abrasive contents. Surface polished by slurries that contain nano-Al abrasives had a lower surface average roughness (Ra), lower topographical variations and less scratching. The material removal amount and the Ra were 124 and 7.61 nm with appropriate values of the process parameters of the oxidizer, oxidizer content, abrasive content, slurry flow rate and polishing time which were H2O2, 2 wt.%, 1 wt.%, 10 ml/min, 5 min, respectively.

Originality/value

– Based on SEM determinations of the process parameters for the polishing of the surfaces, the CMP mechanism was deduced preliminarily.
Wear behaviour of Ti6Al4V alloy blasted with zirconia/hydroxyapatite powders
Authors: Hazar Yoruç A.B. , Elkoca O. , Ekşioğlu Yıldız Harika , Koyun Ahmet
Published: February 2014

Purpose

– The purpose of this paper is to investigate the effect of blasting treatment with zirconia/hydroxyapatite powders on the surface roughness, in vitro bioactivity and wear behavior of Ti6Al4V alloy (Grade V).

Design/methodology/approach

– Ti6Al4V specimens were sandblasted with ZrO2 and HA [Ca10(PO4)6(OH)2] powders in a commercial blasting cabinet. Surface analysis was performed evaluating eroded surfaces by scanning electron microscopy. Roughness surface analysis of the samples was performed with a surface roughness tester and in vitro bioactivity of titanium surfaces was examined in the simulated body fluid (SBF) solution before and after blasting. Wear resistance is evaluated by the weight loss during the test.

Findings

– The highest value of surface roughness is obtained with a mixture of 25 percent ZrO2+75 percent HA (Z25). Z25 exhibited also lower weight loss than Ti6Al4V and other treated samples. These results indicate that surface treatment with 25 percent ZrO2+75 percent HA provides the highest amount of HA adhesion on the surface of Ti6Al4V implant. Finally, the sample surfaces were contacted with SBF solutions for seven days, and Ca/P accumulation was identified on the blasted surfaces. ZrO2/HA blasting method can be used to improve the wear characteristics and the biocompatibility of the implant materials.

Originality/value

– The paper provides information about the effect of ZrO2/HA blasting treatment on the surface properties, in vitro bioactivity and wear behavior of Ti6Al4V implant materials.
Shareholding in EU: is “indirect holding” approach appropriate in achieving financial integration?
Authors: P. Kouretas Georgios , Tarnanidou Christina
Published: February 2014

Purpose

– The purpose of this paper is to focus on the specific “shareholder's” concept of transparency.

Design/methodology/approach

– It considers that indirect securities holding systems limit the degree of “post-trading” transparency. The main concern is that an adverse effect of globalized capital markets is that the actual shareholders are not registered in the official registries and registrations are effected in the name of intermediaries acting on their behalf. It further considers that new EU legislative action should be taken to address the legal issues of securities holdings as a key parameter for EU integration.

Findings

– A new architecture of the securities holding system is proposed in this paper to be adopted at the EU level on the basis of the analyzed direct registration, i.e. registration of all the actual shareholders in the registries. It is considered that this architecture will promote securities holdings transparency for all systems, either direct or indirect, and hence enhance investors' protection and financial confidence in the markets. Focusing on the financial crisis of the recent years, it is worthy of note that a key parameter in solving this crisis problem could be considered not only the imposition of more possible regulatory requirements on all financial players but also the improvement credibility of the markets by making their operation more transparent. Direct registration could be defined as a method of making the markets more transparent in this regard.

Originality/value

– In the light of the financial crisis of 2007-2009, this is one of the first studies, which clearly argues that direct registration could be considered the appropriate method of making the financial markets more transparent. Therefore, it calls for the EU legal intervention should therefore be accelerated. By delaying improvement in the efficiency of the available infrastructures mainly by utilizing all the advantages that technology offers, the markets accept the additional cost of higher risk coverage.
Game theory and sovereign wealth funds
Authors: McVea Harry , Charalambu Nicholas
Published: February 2014

Purpose

– The purpose of this article is to assess strategies available to recipient states for managing the putative risks posed by sovereign wealth funds (SWFs) in the context of global, liberalized, and capital markets.

Design/methodology/approach

– The paper employs a game theory analysis in assessing these risks. Four basic scenarios are outlined whereby recipient states may interact with SWFs: “unselfish recipient state – unselfish SWF” (Option 1); “unselfish recipient state – Selfish SWF” (Option 2); “Selfish Recipient State – unselfish SWF” (Option 3); and “Selfish Recipient State – Selfish SWF” (Option 4).

Findings

– In the light of this analysis, and the balance of risks which the authors perceive recipient states are exposed to in practice, the authors claim that recipient states ought, rationally, to adopt a selfish regulatory strategy irrespective of the strategy which SWFs adopt in practice.

Originality/value

– This claim does not deny the importance of voluntary international measures – such as the “Santiago principles” – in the way SWFs are regulated. Rather, it seeks to show that according to a game theory analysis, and an attempted application of that analysis in practice, undue reliance by recipient states on international “soft law” regulatory initiatives to regulate SWF activity (which constitutes the current international consensus) is strategically unwise.
Trustees and pension schemes in Ireland
Authors: Stewart Jim , McNally Bridget
Published: February 2014

Purpose

– This article aims to highlight the gap between the legal responsibilities and the practice of pension fund trustees in Ireland.

Design/methodology/approach

– The paper relies on primary and secondary data analysis of trustee practice and enforcement cases to highlight the gap between law and practice.

Findings

– The article finds that there is an inconsistency between legal requirement and practice in the calibre of trustee and trustee training across Irish occupational pension schemes. This has adverse consequences for pension governance and performance.

Practical implications

– The findings raise the question as to whether there should be mandatory qualifications for trustees or mandatory standardised trustee training in a prescribed format, with which trustees should comply. It also questions whether there should be a governance code for trustees to ensure a minimum standard or target level of competence and good governance on the part of pension scheme trustees.

Originality/value

– There is a distinct lack of emphasis in the literature and in practice on the inconsistency between the extent of the responsibilities which trustees ultimately carry, and the legal exposure this potentially creates for trustees who unduly rely on other trustees or third parties in the trustee decision making process.
The positive side of call centers: an Indian perspective
Authors: Mukherjee Tuheena , Maheshwari Saurabh
Published: February 2014

Purpose

– Jobs at call centers have received numerous negative undertones. Research has only highlighted the negative impact and dismal psychological consequences of call center jobs on their employees. The purpose of this paper is to investigate the possibilities of positive impact of call center jobs on their employees. The study hypothesizes that the employees working at the call centers with high self-worth (i.e. self-esteem) and high job worth (perceived worth of job (PWJ)) would perceive lesser work stress and have greater job satisfaction.

Design/methodology/approach

– The study is based on data collected from 152 call-center employees through self-reporting questionnaire. Regression and mediation analysis was done to analyze the results.

Findings

– Analysis revealed that those with high self-esteem and high PWJ experience less stress and higher job satisfaction. Stress partially mediates between PWJ and job satisfaction and between self-esteem and job satisfaction. Results confirm that call center jobs do not always create negative impact on the employees and have a positive side too. It is a significant finding for the call center industry which is presently facing high attrition.

Originality/value

– The value of the present study lies in analyzing the importance of PWJ, which is a subjective perception. It is an imperative factor in generating positive or negative effect on the psychological well-being of the employee.
Transformational leadership and psychological empowerment
Authors: Jha Sumi
Published: February 2014

Purpose

– The purpose of this paper is to understand various antecedents of organizational citizenship behavior (OCB). Transformational leadership and psychological empowerment were two independent variables chosen for the study.

Design/methodology/approach

– Standard questionnaires were used to collect data. The sample of 319 employees of different five-star hotels formed the source of data. Frontline employees having two to three subordinates and were from hotels which were in operation at least since last two years, took part in the study.

Findings

– The effect of transformational leadership on OCB has been found to be significant and positive. The moderating effect of psychological empowerment on OCB was also found significant.

Research limitations/implications

– The theoretical development from this paper will contribute toward understanding the antecedents of OCB. The moderating effect of psychological empowerment will reinforce the importance of psychological empowerment.

Practical implications

– It can develop practices to enhance the feeling of psychological empowerment through several training program. Leaders at the top positions shall emphasize on OCB by bringing cultural change.

Originality/value

– This paper probes the OCB's antecedents. It also studied the moderating effect of psychological empowerment on the relationship of transformational leadership and OCB.
Voluntourism product development and wildlife conservation for Thailand
Authors: Sujarittanonta Lavanchawee
Published: February 2014

Purpose

– The aim of this paper is to explore how an international business model was successfully developed to protect the environment, specifically, how the Wild Animal Rescue Foundation (WARF) of Thailand designed its unique eco-voluntourism products.

Design/methodology/approach

– Primary qualitative data were collected through ethnographic research, involving researcher participation and interviews, with the founder and the management team. Secondary data were also gathered through undergraduate and graduate students' experience with WARF, a television news reporter, and social media data from WARF's eco-voluntourists.

Findings

– It was found that the business model of WARF evolved through trial-and-error, whereby voluntourism projects were created in collaboration with stakeholders from both public and private sectors. The success of voluntourism lies in ensuring that the experience was rewarding for all stakeholders.

Practical implications

– WARF's voluntourism business model has high market potential to be developed cross-continents. The findings are optimistic and encouraging for managers and policy makers, particularly for countries that are endowed with natural resources. Eco-tourism and non-service green businesses also found good ideas from WARF to apply to their operations.

Originality/value

– It is extremely challenging to offer a tourism product that could add more value to eco-volunteers who already have high levels of knowledge in ecology. The WARF case demonstrates how extensive stakeholder collaboration makes it possible to create and manage experiences that would be perceived as a rare opportunity for educational eco-tourism.
Responsible tourism in Cyprus: the rhetoric and the reality
Authors: Farmaki Anna , Constanti Panayiotis , Yiasemi Irene , Karis Phidias
Published: February 2014

Purpose

– This paper aims to provide an overview of the approaches that industry stakeholders follow towards responsible tourism in Cyprus and to address the challenges that responsible tourism management faces in a mass tourism destination.

Design/methodology/approach

– In doing so, the paper discusses the concept of responsible tourism and its application in the hospitality and tourism industry. A qualitative research approach was followed whereby roundtable discussions between industry leaders and hospitality educators were initiated in order to identify key challenges. In addition, secondary research was performed with relevant data presented in the paper being previously collected by the CSTI (Cyprus Sustainable Tourism Initiative).

Findings

– Findings reveal that responsible tourism adoption in Cyprus is minimal. Several challenges have been identified as barriers to adoption and successful implementation including poor understanding of the concept, lack of awareness, limited budget, lack of coordination of activities and the absence of an integrated system to ensure cooperation and of a monitoring mechanism.

Practical implications

– The paper will be of immense value to industry practitioners as it represents a holistic understanding of the challenges facing hospitality and tourism industry stakeholders in terms of the implementation of responsible tourism practice. Propositions are made regarding the maximisation of the benefits of responsible tourism.

Originality/value

– The paper draws on sustainability issues in an attempt to shed light on the role of responsible tourism in the hospitality and tourism industry in Cyprus and consequently advances knowledge on responsible tourism management offering value to academics practitioners and students alike.
Body of Knowledge: a practice as research case study on the capacity for dance-theatre to promote wellbeing
Authors: Bicknell Jemma
Published: February 2014

Purpose

– The purpose of this paper is to explore the wellbeing benefits and challenges that arise in dance-theatre performance making with older people. It also addresses the notion of taking artistic risks when making community art.

Design/methodology/approach

– This study draws on current research into older people's participatory performance and the impact it has on wellbeing, in relation to a practice as research dance-theatre project: Body of Knowledge in 2012. The analysis draws on primary experiential and secondary data to describe the possible physical, mental, social and emotional benefits of taking part in performance projects, as well as identifying the challenges and criticisms related to this kind of work.

Findings

– The physical and mental impacts of participating in dance activity are well documented, but there are also valuable social and emotional effects which are hard to quantify, yet just as valuable. Evidence collected from other projects along with my own research, suggests that along with health benefits, the shared endeavour of taking part in a performance project can help an older person to build confidence, social networks, a sense of purpose and refresh or learn new skills. By encouraging older performance groups to show their work to audiences of mixed ages, it is also possible to challenge ageist perceptions.

Originality/value

– This paper draws together current research on the physical, mental, social and emotional value of participatory dance-theatre performance work, in relation to practical findings from a specific project.
Global gene expression in the common scab pathogen, Streptomyces scabies, exposed to potato microtubers
Authors: Dees M.W. , Lysøe E. , Brurberg M.B. , Somervuo P. , Almvik M. , Valkonen J.P.T.
Published: February 2014

Streptomyces scabies causes yield losses in potato by inducing common scab (CS) symptoms on tubers. Little information is available on global gene expression responses in CS‐causing streptomycetes upon interaction with host plants. In this study, expression of 8746 genes was analysed in the type strain of S. scabies (ATCC49173) using a custom‐designed, gene‐specific oligonucleotide microarray. Bacteria were grown in liquid yeast malt extract (YME) medium and 480 genes were found to be up‐regulated 24 h after supplementing the cultures with potato microtubers. Quantitative PCR analysis of eight putative or known virulence genes was consistent with the microarray data. Elevated expression of the thaxtomin synthesis gene txtA and txtR genes regulating synthesis of thaxomin A, the main pathogenicity factor of S. scabies, and production of thaxtomin A were detected in cultures containing microtubers. Unexpectedly, thaxtomin was also detected in cultures lacking microtubers, which indicated that growth in YME induces thaxtomin production in S. scabies. Many but not all microtubers incubated in the cultures of S. scabies for 48 h displayed symptoms, indicating that the microtubers were not equally susceptible even though they were produced under uniform in vitro growth conditions. These factors may have limited the differences in gene expression observed between S. scabies exposed to microtubers compared to controls. This study provides some of the first results on the transcriptome of S. scabies, a widely distributed and important potato pathogen, upon exposure to young developing potato tubers. The findings will inform future studies on interactions of CS‐inducing streptomycetes with potato and means to control the disease.
Stable isotopic evidence for Middle Pleistocene environmental change from a loess‐paleosol sequence: Kärlich, Germany
Authors: Gallant Claire E. , Candy Ian , van den Bogaard Paul , Silva Barbara N. , Turner Elaine
Published: February 2014

Loess‐paleosol sequences are important terrestrial archives of palaeoenvironmental change. Such sequences are rich in pedogenic carbonate, the oxygen and carbon isotopic values of which can provide important palaeoenvironmental information. Although some studies have pioneered the use of O and C isotopes in loess‐paleosol sequences, they are not routinely used as palaeoclimate proxies. In this study we analysed the sedimentology, micromorphology, geochronology and isotopic geochemistry of a Middle Pleistocene loess‐paleosol section, located at Kärlich, Germany. The section studied correlates with the Elsterian glacial (MIS 12) and Holsteinian interglacial (MIS 11). Embedded tephra layers yielded 40Ar/39Ar ages of 466±3 ka, 447±1 ka and 361±3 ka. The sedimentology and micromorphology of the sequence record a shift from accretionary loess accumulation (MIS 12) to prolonged pedogenesis at a stable land surface (MIS 11). Soil carbonate δ18O values record an enrichment of ∼3‰ during the accumulation of the loess, reaching peak values comparable with those found in the MIS 11 soil. The δ18O signal is interpreted as reflecting temperature, highlighting the potential of δ18O analysis of European loess soil carbonates as a means of reconstructing palaeotemperature history.
Mid‐Holocene vegetation dynamics in the Tejo River estuary based on palaeobotanical records from Ponta da Passadeira (Barreiro–Setúbal, Portugal)
Authors: Gómez‐Orellana Luis , Ramil‐Rego Pablo , Badal Ernestina , Carrión Marco Yolanda , Muñoz Sobrino Castor
Published: February 2014

This paper presents the results of pollen and charcoal analyses carried out in the sedimentary formation of Ponta da Passadeira, south of the Tejo River estuary, Portugal. The data provide information regarding the evolution of the coastline and ecosystem of the estuary during the mid and late Holocene. The study focuses on a group of upright woody fossilized tree remains that, together with those identified earlier by García‐Amorena et al. (2007), form part of the fossil forest of Ponta da Passadeira. Eight remains were identified as Pinus pinaster, four as Pinus pinea and one as Pinus sp. Two specimens of these species were dated to 6523 and 5805 cal. a BP. Pollen analysis was undertaken in a clay layer located at the same point as the fossil forest, which is currently below sea level; the base of the clay layer was dated to 4906 cal. a BP. The pollen spectra reflect the dynamics of the vegetation that grew on this deposit, whereas the sporopollinic input masks the contribution of the regional vegetation. Wood charcoal remains recovered at an adjacent Final Neolithic settlement were also analysed, and a Pinus sp. specimen was radiocarbon dated to 5050 cal. a BP. The correlation amongst the three records provides key ecological markers for the understanding of the evolution of coastline ecosystems, and helps to clarify and understand the Holocene sea rise on the Atlantic seaboard of Iberia. The geographical location of Ponta da Passadeira is strategic because it enables a more clear definition of the configuration of landscapes that show an inflection point in this area of central Portugal.
Modelling community, family, and individual determinants of childhood dental caries
Authors: Duijster Denise , van Loveren Cor , Dusseldorp Elise , Verrips Gijsbert H. W.
Published: February 2014

This cross‐sectional study empirically tested a theoretical model of pathways and inter‐relationships among community, family, and individual determinants of childhood dental caries in a sample of 630, 6‐year‐old children from the Netherlands. Children's decayed, missing, and filled teeth (dmft) scores were extracted from dental records. A validated parental questionnaire was used to collect data on sociodemographic characteristics, psychosocial factors, and oral hygiene behaviours. Data on neighbourhood quality were obtained from the Dutch Central Bureau of Statistics. Structural equation modelling indicated that the model was valid after applying a few modifications. In the revised model, lower maternal education level was related to poorer family organization, lower levels of social support, lower dental self‐efficacy, and an external dental health locus of control. These, in turn, were associated with poorer oral hygiene behaviours, which were linked to higher levels of childhood dental caries. In addition, lower maternal education level and poorer neighbourhood quality were directly associated with higher caries levels in children. This model advances our understanding of determinants of childhood dental caries and the pathways in which they operate. Conception of these pathways is essential for guiding the development of caries‐preventive programmes for children. Clues for further development of the model are suggested.
Robust Control of Automotive Active Seat-Suspension System Subject to Actuator Saturation
Authors: Gu Zhou , Fei Shumin , Zhao Yaqin , Tian Engang
Published: February 2014

This paper deals with the problem of robust sampled-data control for an automotive seat-suspension system subject to control input saturation. By using the nature of the sector nonlinearity, a sampled-data based control input saturation in the control design is studied. A passenger dynamic behavior is considered in the modeling of seat-suspension system, which makes the model more precisely and brings about uncertainties as well in the developed model. Robust output feedback control strategy is adopted since some state variables, such as, body acceleration and body deflection, are unavailable. The desired controller can be achieved by solving the corresponding linear matrix inequalities (LMIs). Finally, a design example has been given to demonstrate the effectiveness and advantages of the proposed controller design approach.
Design and Control of a Sleeve Muscle-Actuated Robotic Elbow
Authors: Driver Tad A. , Shen Xiangrong
Published: February 2014

This paper describes the design and control of a robotic elbow system, which is actuated with a novel sleeve muscle actuator. The sleeve muscle is a significant step forward from the traditional pneumatic muscle, and provides a substantially improved performance through a fundamental structural change. Specifically, the sleeve muscle incorporates a cylindrical insert to the center of the pneumatic muscle, which eliminates the central portion of the internal volume. As a result of this change, the sleeve muscle provides multiple advantages over the traditional pneumatic muscle, including the increased force capacity over the entire range of motion, reduced energy consumption, and expedited dynamic response. Furthermore, utilizing the load-bearing tube as the insert, the sleeve muscle enables an innovative “actuation-load bearing” structure, which generates a highly compact robotic system to mimic the structure and functionality of biological limbs. The robotic elbow design in this paper serves an example that shows the design and control process of a robotic joint in this integrated structure. This robotic elbow provides a range of motion of 110 deg, approximately 80% of that for a human elbow, and an average torque capacity that exceeds the peak torque of the human elbow. The servo control capability is provided with a model-based sliding-mode control approach, which is able to provide good control performance in the presence of disturbances and model uncertainties. This controller is implemented on the robotic elbow prototype, and the effectiveness was demonstrated with step response and sinusoidal tracking experiments.
The Optimality of the Handbrake Cornering Technique
Authors: Tavernini Davide , Velenis Efstathios , Lot Roberto , Massaro Matteo
Published: February 2014

The paper investigates the optimality of the handbrake cornering, a strategy widespread among rally drivers. Nonlinear optimal control techniques are used to mimic real driver behavior. A proper yet simple cost function is devised to induce the virtual optimal driver to control the car at its physical limits while using the handbrake technique. The optimal solution is validated against experimental data by a professional rally driver performing the handbrake technique on a loose off-road surface. The effects of road surface, inertial properties, center of mass position, and friction coefficient are analyzed to highlight that the optimality of the maneuver does not depend on the particular vehicle data set used. It turns out that the handbrake maneuvering corresponds to the minimum time and minimum (lateral) space strategy on a tight hairpin corner. The results contribute to the understanding of one of the so-called aggressive driving techniques.
Fabrication and Characterization of Carbon Nanotube Nanocomposites Into 2024-T3 Al Substrates Via Friction Stir Welding Process
Authors: Misak H. E. , Widener C. A. , Burford D. A. , Asmatulu R.
Published: February 2014

Carbon nanotube (CNT)-aluminum (Al) nanocomposites were prepared using friction stir welding (FSW) processing, and then the mechanical properties of these nanostructured materials were determined using the universal MTS machine. The fabrication of the CNT-metal composite consisted of the following steps: (a) homogenizing the CNTs and Al powder at three different ratios: 0/100, 25/75, and 50/50, (b) compacting the mixtures into grooves that were initially machined into the substrate (2024-T3) for the three cases, (c) incorporating CNTs in a substrate by the FSW process, and (d) validating the dispersion of the CNTs into the Al substrates after the characterization steps. Scanning electron microscopy (SEM) analysis and other physical characterization tests (e.g., mechanical, metallography, and fracture surfaces) were conducted on the prepared substrates. Test results showed that CNTs were dispersed and aligned uniquely in the different locations of the metal structures depending on the FSW zones: advancing, retreating, transverse, and stir zone regions. The mechanical properties of each zone were also compared to the distribution of CNTs. The advancing side had the highest amount of CNTs mixed into the aluminum substrate while retaining the yield strength (YS); however, the elongation was reduced. The retreating side had little to no CNTs distributed into the substrate and the mechanical properties were not significantly affected. The stir zone YS had little influence of the CNTs at the lower CNT/Al powder ratio (25/50), but a significant effect was noticed at the higher ratio of 50/50. The elongation to failure was significantly affected for both cases. The transverse zone YS and elongation to failure was significantly reduced by the powder mixtures. These results may open up new possibilities in the aircraft and other manufacturing industries for future development in the field.
Diffusion Theory Applied to Tool-Life Stochastic Modeling Under a Progressive Wear Process
Authors: Braglia Marcello , Castellano Davide
Published: February 2014

In this paper, a novel approach to the derivation of the tool-life distribution, when the tool useful life ends after a progressive wear process, is presented. It is based on the diffusion theory and exploits the Fokker–Planck equation. The Fokker–Planck coefficients are derived on the basis of the injury theory assumptions. That is, tool-wear occurs by detachment of small particles from the tool working surfaces, which are assumed to be identical and time-independent. In addition, they are supposed to be small enough to consider the detachment process as continuous. The tool useful life ends when a specified total volume of material is thus removed. Tool-life distributions are derived in two situations: (i) both Fokker–Planck coefficients are time-dependent only and (ii) the diffusion coefficient is neglected and the drift is wear-dependent. Theoretical results are finally compared to experimental data concerning flank wear land in continuous turning of a C40 carbon steel bar adopting a P10 type sintered carbide insert. The adherence to the experimental data of the tool-life distributions derived exploiting the Fokker–Planck equation is satisfactory. Moreover, the tool-life distribution obtained, when the diffusion coefficient is neglected and the drift is wear-dependent, is able to well-represent the wear behavior at intermediate and later times.
Nonlinear Analysis of Mineral Wool Fiberization Process
Authors: Bizjan Benjamin , Širok Brane , Govekar Edvard
Published: February 2014

In this paper, the mineral wool fiberization process on a spinner wheel was studied by means of the nonlinear time series analysis. Melt film velocity time series was calculated using computer-aided visualization of the process images recorded with a high speed camera. The time series was used to reconstruct the state space of the process and was tested for stationarity, determinism, chaos, and recurrent properties. Mineral wool fiberization was determined to be a low-dimensional and nonstationary process. The 0–1 chaos test results suggest that the process is chaotic, while the determinism test indicates weak determinism.
Evaluation of Cutting Fluid With Nanoinclusions
Authors: Amrita M. , Srikant R. R. , Sitaramaraju A. V.
Published: February 2014

Environmental and economic concerns on use of cutting fluids have led to use of minimum quantity cooling lubrication (MQCL) system, which uses minute quantity of cutting fluids, demanding a specialized fluid with improved properties. Investigation of any newly developed cutting fluid would be complete if it is evaluated with respect to its machinability, environmental and economic aspects. The present work investigates the viscosity, machinability characteristics, environmental effects, and economic aspects of a newly developed nanocutting fluid with varying concentrations of graphite nanoparticles applied at different flow rates to machining operation. It is found that the machinability improved with respect to conventional cutting fluid and this improvement increased with increase in concentration of nanoinclusions in the range 0.1–0.5 wt. % and also with increase in the flow rate. A regression model is developed for nanocutting fluids to estimate tool wear when used in the range 0.1–0.5 wt. % at flow rates 5 ml/min to 15 ml/min. The biodegradability is found to decrease with inclusion of nanoparticles due to the inorganic nature of selected nanoparticle. But its application as MQCL is ecofriendly as the nanocutting fluid is not disposed to the environment and graphite in it is neither toxic nor hazardous. Based on economic aspect, MQCL application with conventional cutting fluid and few cases of nanocutting fluids are found to be economic compared to flood lubrication. So a compromise has to be obtained between the economic and machinability aspects to choose an optimum cutting fluid.
A Rankine Panel Method for Added Resistance of Ships in Waves
Authors: Söding Heinrich , Shigunov Vladimir , Schellin Thomas E. , Moctar Ould el
Published: February 2014

A new Rankine panel method and an extended Reynolds-Averaged Navier–Stokes (RANS) solver were employed to predict added resistance in head waves at different Froude numbers of a Wigley hull, a large tanker, and a modern containership. The frequency domain panel method, using Rankine sources as basic flow potentials, accounts for the interaction of the linear periodic wave-induced flow with the nonlinear steady flow caused by the ship's forward speed in calm water, including nonlinear free surface conditions and dynamic squat. Added resistance in waves is obtained by the pressure integration method. The time domain RANS solver, based on a finite volume method, is extended to solve the nonlinear equations of the rigid body six-degrees-of-freedom ship motions. The favorable comparison of the panel and RANS predictions demonstrated that the Rankine method is suitable to efficiently obtain reliable predictions of added resistance of ships in waves. Comparable model test predictions correlated less favorably, although the overall agreement was felt to be acceptable, considering the difficulties associated with the procedures to obtain accurate measurements.
Optimal Design of a Helmholtz Resonator With a Flexible End Plate
Authors: Kurdi Mohammad H. , Scott Duncan G. , Nudehi Shahin S.
Published: February 2014

This paper describes a design process that produces a small volume Helmholtz resonator capable of achieving high transmission loss across a desired frequency range. A multiobjective optimization formulation was used to design a Helmholtz resonator with a flexible end plate. The optimization formulation generated a Pareto curve of design solutions that quantify the trade-off between the optimization goals: minimum resonator volume and maximum transmission loss across a specified frequency range. The optimization problem was formulated and solved in the following manner. First, a mathematical formulation for the transmission loss of the Helmholtz resonator with a flexible plate was completed based on the resonator design parameters. Then, the weighted transmission loss across a specified frequency range and a minimum resonator volume were defined as optimization objectives. Finally, the Pareto curve of optimum design solutions was calculated using a gradient-based approach via the ɛ-constraint method. The optimization results allow the designer to select resonator design parameters that meet the requirements for both transmission loss and resonator volume. To validate the optimization results, two optimal Helmholtz resonators were manufactured and experimentally confirmed.
“Eclipse” Bifurcation in a Twinkling Oscillator
Authors: Panigrahi Smruti R. , Feeny Brian F. , Diaz Alejandro R.
Published: February 2014

This work regards the use of cubic springs with intervals of negative stiffness, in other words, “snap-through” elements, in order to convert low-frequency ambient vibrations into high-frequency oscillations, referred to as “twinkling.” The focus of this paper is on the bifurcation of a two-mass chain that, in the symmetric system, involves infinitely many equilibria at the bifurcation point. The structure of this “eclipse bifurcation” is uncovered, and perturbations of the bifurcation are studied. The energies associated with the equilibria are examined.
Water/Steam Treatment Programs and Chemistry Control for Heat Recovery Steam Generators
Authors: Buecker Brad
Published: February 2014

New power generation in the U.S. is being dominated by installation of combined-cycle power plants, where a significant portion of the power is produced from steam turbines supplied by heat recovery steam generators (HRSG). Proper chemistry control and monitoring of HRSG feedwater, boiler water, and steam are essential for high reliability and availability of these units. However, many plants have minimal staff, most if not all of whom have no formal chemistry training and who may not fully understand the importance of water/steam chemistry and monitoring techniques. This paper provides an outline of the most important chemistry control methods and also examines the phenomenon of flow-accelerated corrosion (FAC). FAC is the leading cause of corrosion in HRSGs,[1] and is often the result of the outdated belief that oxygen scavengers are a requirement for feedwater treatment. Since 1986, FAC-induced failures at several coal-fired power plants have killed or injured a number of U.S. utility workers.
Balancing Pulverizer-Burner Coal Flows: The Complete Solution
Authors: Peet William J.
Published: February 2014

Since the introduction of direct firing pulverizers to power generation in the 1920’s, the inability to balance the coal flows among the multiple burner lines has eluded the industry. Many believed that the problem lay in unequal burner line equivalent lengths and sought to remedy the situation by inserting additional bends, orifices etc. to the shorter lines. Current practice by the supplier is to achieve a maximum deviation of +/− 5% air flow in a clean air test but coal flow deviations are typically +/− 35%, or higher, when tested. The impact of uneven coal flows on the side to side imbalance within the furnace and boiler is detrimental to the unit operation from emissions to thermodynamic performance and maintenance costs.

This paper will derive the governing equation for the two phase flow in the burner lines. From this equation a simple method for on-line measurement will be developed and a robust control solution for coal flow balancing described.
Testing Standards, Methods and Guidelines for Steam Surface Condensers: A Summary of the Options Available to Plant Operators for Ensuring Equipment Reliability and Maintaining Unit Performance
Authors: Nightingale Darren M.
Published: February 2014

The availability and operational efficiency of a steam surface condenser is a critical aspect of, and significant contributor to, a power plants overall thermal performance. In order to ensure reliability and maintain operational efficiency, inspection and testing is often required to determine the condition of the condenser. Inspections tend to support condition based maintenance and usually assist with monitoring the real time condition of the condenser, they are essentially reactive. Regular testing has the advantage that it can be pro-active and provide valuable benchmark data which in turn can be used to monitor a condensers condition throughout its operational design life, and beyond. Testing also provides valuable recordable information which can be utilized in preventive maintenance regimes to minimize condenser deterioration, thereby helping to ensure peak efficiency, and in some instances it can even be used within predictive failure models. Testing often greatly assists with avoiding expensive & unnecessary shutdowns by helping to determine optimal timing for any necessary remedial and/or major repair work, as well as helping to identify and address real time issues.