bluuebunny/crossref_metadata_2025 huggingface dataset:
Pre‐commercial procurement: a demand or supply policy instrument in relation to innovation?
Authors: Edquist Charles , Zabala‐Iturriagagoitia Jon Mikel
Published: April 2014

In 2006, the European Commission introduced the concept of ‘pre‐commercial procurement’ (PCP) as an instrument to promote innovation and to mitigate grand challenges. One of the main motives for the support of PCP schemes was to use public needs as a driver for innovation. This concept was also introduced as a response to the need to reinforce the innovation capabilities of the European Union while improving the quality and efficiency of public services.

But what is meant by PCP? Is it a demand‐ or a supply‐side instrument in relation to innovation? This is the research question addressed in this paper, the goal being motivated by the lack of academic discussion in this direction.

The paper is based on three cases, one from the Netherlands, one from the United Kingdom and one from Australia. These cases provide evidence that PCP is a matter of research and development (R&D) funding of a targeted kind, geared toward very specific goals and in a focused way. This leads the authors to conclude that PCP is a supply‐side policy instrument in relation to innovation. In this sense, they would like to raise a flag for going back to the origins of the PCP program and calling it a ‘precompetitive R&D program’, rather than labeling it as an innovation procurement instrument.
Low‐flow oxygen: How much is your patient really getting?
Authors: McDonald Christine F.
Published: April 2014

See article, page 538
Paraneoplastic Hu and CRMP5 antibodies are present in smokers without cancer or neurological disease
Authors: Qvale Tor H. , Storstein Anette , Mazengia Kibret , Eagan Tomas M.L. , Bakke Per S. , Vedeler Christian A.
Published: April 2014

Background and objective

We investigated if the paraneoplastic Hu and collapsin response mediator protein 5 (CRMP5) antibodies could be used as early markers for lung cancer in smokers with or without chronic obstructive pulmonary disease (COPD).

Methods

Hu and CRMP5 antibodies were measured by radioimmunoprecipitation assay (RIPA) in sera from 552 smokers; 379 with and 173 without COPD. Three hundred blood donors served as controls. The positive sera were also tested by indirect immunofluorescence and line blot with recombinant proteins. The 552 smokers were matched with data from the Cancer Registry of Norway, and the hospital medical records from the subjects positive for Hu and CRMP5 antibodies were reviewed. The mean follow‐up time was 4.4 years (range 2.5–5.7 years).

Results

The RIPA showed that 5/379 (1.3%) smokers with COPD had Hu antibodies and 1/379 (0.3%) smokers with COPD had CRMP5 antibodies. Only the smoker with the highest RIPA index had Hu antibodies also detected by immunofluorescence and line blot. One of 173 (0.6%) smokers without COPD had Hu antibodies, but none had CRMP5 antibodies. None of the 300 controls had Hu antibodies, but 2/300 (0.7%) had CRMP5 antibodies. Hu antibodies remained positive for more than 5 years. No cancer or neurological disease was recorded in the Hu or CRMP5 positive patients. The total cancer frequency in the smokers with and without COPD was 70/552 (13%).

Conclusions

Hu and CRMP5 antibodies were not associated with cancer or neurological disease in a large cohort of smokers and are therefore not always paraneoplastic.
Bilateral versus Multilateral Free Trade Agreements: A Welfare Analysis
Authors: Yilmazkuday Demet , Yilmazkuday Hakan
Published: April 2014

Why is a proliferation of bilateral free trade agreements (FTAs) between certain types of countries observed instead of progress in attaining global free trade through a multilateral FTA? This paper answers this question by exploring the enforceability of different types of FTAs through comparing minimum discount factors that are necessary to sustain them in an infinitely repeated game framework. The authors search for the globally welfare maximizing trade agreements that are sustainable under different conditions. The results depict that transportation costs, differences in country sizes and comparative advantages are all obstacles for having a multilateral FTA. Accordingly, international development policies conducted for the removal of such obstacles should be the main goal toward achieving a multilateral FTA, which is shown to be the first‐best solution to the maximization problem of global welfare.
Does Citizenship Status Matter in Canadian Agriculture? Workplace Health and Safety for Migrant and Immigrant Laborers
Authors: Preibisch Kerry , Otero Gerardo
Published: April 2014

This article explores how precarious legal status circumscribes differential inclusion in the agricultural labor market and affects workers' lives through a comparative study of workplace health and safety among temporary migrant guest workers and immigrants in Canada. Original, multimethod research with South Asian immigrant and Mexican migrant farmworkers examines employment practices, working conditions, and health‐care access. We find that both groups engage in precarious work, with consequences for their health and safety, including immigrant workers with citizenship. Nevertheless, migrant guest workers are subject to more coercive forms of labor discipline and a narrower range of social protection than immigrants. We argue that while formal citizenship can mitigate some dimensions of precariousness for farmworkers racialized as non‐white, achieving a more just, safer food system will require broader policies to improve employer compliance and address legislative shortcomings that only weakly protect agricultural labor.
Selection of Latent Variables for Multiple Mixed‐outcome Models
Authors: Zhou Ling , Lin Huazhen , Song Xinyuan , Li Yi
Published: April 2014

Latent variable models have been widely used for modelling the dependence structure of multiple outcomes data. However, the formulation of a latent variable model is often unknown a priori, the misspecification will distort the dependence structure and lead to unreliable model inference. Moreover, multiple outcomes with varying types present enormous analytical challenges. In this paper, we present a class of general latent variable models that can accommodate mixed types of outcomes. We propose a novel selection approach that simultaneously selects latent variables and estimates parameters. We show that the proposed estimator is consistent, asymptotically normal and has the oracle property. The practical utility of the methods is confirmed via simulations as well as an application to the analysis of the World Values Survey, a global research project that explores peoples’ values and beliefs and the social and personal characteristics that might influence them.
HLA‐A*02:466, a variant of HLA‐A*02, discovered in a Taiwanese unrelated hematopoietic stem cell donor
Authors: Yang K. L. , Lee S. K. , Lin P. Y.
Published: April 2014

One nucleotide replacement at residue 228 of the human leukocyte antigen HLA‐A*02:03:01 results in a novel allele, HLA‐A*02:466.
Role of Adaptor Proteins and Clathrin in the Trafficking of Human Kidney Anion Exchanger 1 (kAE1) to the Cell Surface
Authors: Junking Mutita , Sawasdee Nunghathai , Duangtum Natapol , Cheunsuchon Boonyarit , Limjindaporn Thawornchai , Yenchitsomanus Pa‐thai
Published: April 2014

Kidney anion exchanger 1 (kAE1) plays an important role in acid–base homeostasis by mediating chloride/bicarbornate (Cl−/HCO3−) exchange at the basolateral membrane of α‐intercalated cells in the distal nephron. Impaired intracellular trafficking of kAE1 caused by mutations of SLC4A1 encoding kAE1 results in kidney disease – distal renal tubular acidosis (dRTA). However, it is not known how the intracellular sorting and trafficking of kAE1 from trans‐Golgi network (TGN) to the basolateral membrane occurs. Here, we studied the role of basolateral‐related sorting proteins, including the mu1 subunit of adaptor protein (AP) complexes, clathrin and protein kinase D, on kAE1 trafficking in polarized and non‐polarized kidney cells. By using RNA interference, co‐immunoprecipitation, yellow fluorescent protein‐based protein fragment complementation assays and immunofluorescence staining, we demonstrated that AP‐1 mu1A, AP‐3 mu1, AP‐4 mu1 and clathrin (but not AP‐1 mu1B, PKD1 or PKD2) play crucial roles in intracellular sorting and trafficking of kAE1. We also demonstrated colocalization of kAE1 and basolateral‐related sorting proteins in human kidney tissues by double immunofluorescence staining. These findings indicate that AP‐1 mu1A, AP‐3 mu1, AP‐4 mu1 and clathrin are required for kAE1 sorting and trafficking from TGN to the basolateral membrane of acid‐secreting α‐intercalated cells.
Lethal autoimmune hemagglutination due to an immunoglobulin A autoagglutinin with Band 3 specificity
Authors: Salama Abdulgabar , Janvier Daniel , Mayer Beate , Saison Carole , Moscatelli Henriette , Aucouturier Françoise , Yilmaz Pinar , Arnaud Lionel , Wild Vanessa , Knop Stefan , Cartron Jean‐Pierre
Published: April 2014

Background

We describe a patient with a high‐titer warm immunoglobulin (Ig)A autoantibody resulting in death due to hemagglutination rather than to hemolysis.

Case Report

A 47‐year‐old male patient presented with an intriguing pronounced vascular erythema of the skin. A livedo reticularis associated with cold agglutinin of high thermal amplitude was suspected. The patient's condition unexpectedly and abruptly deteriorated resulting in death 3 days after admission.

Study Design and Methods

Conventional serologic procedures and immunochemical methods were used.

Results

Serologic and immunochemical examinations revealed a warm IgA autoantibody of high titer with anti‐Band 3 specificity. Although the patient presented with severe anemia, only mild signs of hemolysis were observed, with no evidence of complement activation. The autopsy revealed an enormous accumulation of agglutinated red blood cells in liver and spleen and a B‐cell lymphoma and cerebral edema. Thus, the patient's death was largely caused by hypoxia related to hemagglutination rather than to hemolysis and/or anemia per se.

Conclusion

Strongly hemagglutinating antibodies may not only cause immune hemolysis but also hypoxia due to intravascular hemagglutination.
Feline secondary spontaneous pneumothorax: A retrospective study of 16 cases (2000–2012)
Authors: Liu Debra T. , Silverstein Deborah C.
Published: April 2014

Objective

To describe the demographics, clinical characteristics, diagnostic findings, underlying etiologies, treatment, and outcome associated with secondary spontaneous pneumothorax (SSP) in cats; and to identify clinical feature differences among cats with asthma associated secondary spontaneous pneumothorax (AASSP) versus nonasthma‐associated secondary spontaneous pneumothorax (NAASSP).

Design

Retrospective case series.

Setting

University teaching hospital.

Animals

Sixteen client‐owned cats with secondary spontaneous pneumothorax.

Interventions

None.

Measurements and Main Results

Domestic short hair was the predominant breed in this study (n= 15). The median age was 8 years old (range: 7 weeks to 17 years) with no sex predilection. Fourteen cats were affected by multi‐lobar pulmonary pathology of infectious, inflammatory, or neoplastic causes. Asthma was the most common cause of spontaneous pneumothorax (25%). Ten of 12 treated cats survived the initial episode of spontaneous pneumothorax to discharge with medical management, including all 4 cats with AASSP. Reoccurrence was documented in 4 cats. Pulmonary lobectomy was curative for 1 cat with congenital accessory lung lobe emphysema. No difference in clinical presentation was identified between cats with AASSP and cats with NAASSP.

Conclusions

Feline SSP is frequently associated with extensive pulmonary pathology. Supportive medical management is most appropriate, except in rare cases with focal congenital abnormalities that may benefit from surgical intervention. AASSP appears to carry a good prognosis for short‐term outcome (survival to discharge). Clinical assessment, imaging, and invasive diagnostics were required to differentiate between AASSP and NAASSP.
EVALUATION OF TRADITIONAL AND NOVEL RADIOGRAPHIC VERTEBRAL RATIOS IN GREAT DANES WITH VERSUS WITHOUT CERVICAL SPONDYLOMYELOPATHY
Authors: Martin‐Vaquero Paula , da Costa Ronaldo C.
Published: April 2014

Great Danes are predisposed to osseous‐associated cervical spondylomyelopathy (Wobbler syndrome). The first aim of this prospective study was to compare values measured using previously published intravertebral and intervertebral ratio methods and a novel ventrodorsal ratio method in radiographs of clinically normal and affected Great Danes. The second aim was to determine whether these ratios could be used as predictors of sites of spinal cord compression based on magnetic resonance imaging (MRI). Thirty dogs (15 normal, 15 affected) were prospectively enrolled. Lateral and ventrodorsal radiographs were obtained and six measurements were recorded from C3‐T1. For each vertebral location, intravertebral ratios and intervertebral ratios were calculated from lateral views, and the ratio of the distance between the articular process joints vs. vertebral body width (novel ventrodorsal ratio) was calculated from ventrodorsal views. Values for these three ratios were compared, by vertebral location and dog group. Intravertebral and intervertebral ratios did not differ between dog groups. The ventrodorsal ratio was significantly smaller in affected Great Danes at C5–6 (P= 0.005) and C6–7 (P< 0.001). The ventrodorsal ratio was significantly associated with MRI presence of spinal cord compression. For each 0.1 unit increase in this ratio value, there was a 65% decrease in the odds of spinal cord compression being present at that site, independent of vertebral location (P= 0.002). Findings from this study supported use of the novel ventrodorsal ratio as an initial radiographic screening method for Great Danes with suspected cervical spondylomyelopathy.
Best Practices for Planning Events Encouraging Human–Animal Interactions
Authors: Erdozain G. , KuKanich K. , Chapman B. , Powell D.
Published: April 2014

Educational events encouraging human–animal interaction include the risk of zoonotic disease transmission. It is estimated that 14% of all disease in the USA caused by Campylobacter spp., Cryptosporidium spp., Shiga toxin‐producing Escherichia coli (STEC) O157, non‐O157 STECs, Listeria monocytogenes, non‐typhoidal Salmonella enterica and Yersinia enterocolitica were attributable to animal contact. This article reviews best practices for organizing events where human–animal interactions are encouraged, with the objective of lowering the risk of zoonotic disease transmission.
Torque Vibrations in Automatized Screw Assembly: Reasons, Elimination and Virtual Testing
Authors: Hoernig T. , Kopfer H. W. , Friedrich C.
Published: April 2014

Today the torque controlled tightening method for screw assembly is an established process in industries undertaking large scale productions [12]. In this tightening method an instability of friction during the tightening procedure leads to an imprecise stop of the electronic tightening tool affecting the preload. Besides this heavy noise emission occurs due to vibrations.

Because of shorter and shorter cycle times in automated screw assembly, higher precision requirements, new surface pairings (e.g. Cr(VI)-free) with changed coefficients of friction and more complex assemblies with difficult access to the joint, result in an increased number of torque vibrations on automatized screw assembly (also called stick-slip). Due to highly interconnected production flows, the productivity is hereby significantly interrupted. This means significant financial loss because of a small screw which stops the entire production line. This contribution entitles the reasons for the origin of torque vibrations as well as advices for elimination.
Acoustic Emission and Ultrasound Phased Array Technique for Composite Material Evaluation
Authors: Taheri Hossein , Delfanian Fereidoon , Du Jikai
Published: April 2014

The successful application of various acoustic evaluation techniques to composite materials and structures depends on the understanding of the acoustic wave propagation mechanisms. However, due to the anisotropic nature of composite materials, where the acoustic signal velocity and attenuation depend on its traveling direction, the correlation of the different material failure modes to the recorded acoustic signals, such as during of an acoustic emission (AE) inspection, is difficult to be defined. This issue becomes even more challenging for ultrasound phased array technique, where unlike a conventional ultrasound single element transducer, an ultrasound phased array of sensors will generate and receive acoustic energy at various desired directions and locations. Such heightened flexibility and sensitivity is essential for the complex shape of modern composite structures. In this paper, the influence of fiber orientation on AE signal was first studied. AE parameters such as counts, duration, energy, rise time and amplitude for aluminum and composite plate were analyzed in MS-Excel and results were compared to AE software. Acoustic velocities along various fiber directions were also theoretically studied and experimentally measured. Then ultrasound phased array technique and related parameters such as ultrasound beam angle and focusing, frequency and material attenuation factors were quantitatively analyzed, and the optimization and limitation of ultrasound phased array inspection procedure were summarized.
Modeling Heat Flow Interaction With Defects in Composite Materials Using Virtual Heat Sources in Pulsed Thermography
Authors: Manohar Arun , Lanza di Scalea Francesco
Published: April 2014

Quantitative defect detection in composite structures is an important problem as the aerospace and wind energy industries are increasingly using composites due to their attractive properties. Newer aircraft contain over 50% composites, while the wind turbine blades contain over 95% composites. Quantitative estimation of defect parameters is relevant to perform repairs and assess the integrity of these structures. Previous studies are based on simple 1D heat conduction models, which are inadequate in predicting heat flow around defects, especially in composites where the ratio of longitudinal to transverse thermal conductivity is about 100. In this study, a novel heat conduction model is proposed to model heat flow around defects accounting for 3D heat conduction in quasi-isotropic composites. The validity of the proposed methodology is established using experiments performed on a CFRP panel containing defects of different dimensions at different depths. The inverse problem could be used to quantitatively determine the defect depth and size.
Low-Cost Chemical Sensors Based on Shrink Polymer Microfluidics
Authors: Zhang Bo , Cui Tianhong
Published: April 2014

A low-cost chemical sensor based on shrink polymer was presented in this paper. Graphene nanoplatelets were self-assembled on the inner surface of microchannel formed by shrink polymer. The low-cost sensor system can give stable and precise results by only consuming 1 μL reagent, demonstrating great advantage over planar sensor. With assistance of self-assembly and shrink polymer, the sensor can be realized in a simple low-cost way.
Dynamic Analysis for Cryogenic and High Pressure Fueling Valve of Combustion Light Gas Gun System
Authors: Liu Yang , Song Xiaodong , Yao Xiaoxian , Li Kun
Published: April 2014

The paper describes the dynamic behaviors of a unique cryogenic and extra-high pressure pneumatic valve for the high pressure gaseous medium injection of combustion light gas gun (CLGG), which is known as a unique technique to achieve hypervelocity projectile. As a critical component of the CLGG’s injecting system, the operation principle and dynamic property of the valve are detailedly investigated by means of theoretical and experimental way. The problem of needing large driving power and slowing response in extra-high pressure pneumatic on-off valve is solved by means of lever pneumatic force balance method. A two-stage valve that used a two-position five-port pilot solenoid plunger valve to control a large flow-rate poppet valve is developed. The definitions and rules of a dynamic processes based on the critical pressure points in the control chamber are put forward. The mathematical models of the valve are obtained based on above definitions and rules. The paper show that the valve’s dynamic property obtained from the modeling and simulation is in accordance with the experiment results. The main work of this paper concentrates on investigating the operation principle, mathematical model and dynamic characteristics of the new cryogenic and high pressure fueling valve of CLGG system.
Energy and Mission Optimization of an Airship by Constructal Design for Efficiency Method
Authors: Trancossi Michele , Dumas Antonio , Madonia Mauro
Published: April 2014

It is possible to define a novel design method, which aims overcoming both traditional, the traditional Multidisciplinary Design Optimization, and to solve a fundamental issue relating to the actual formalization of the Constructal optimization method. It aims only to enhance and integrate the constructal design method and aims to produce designs, which could be, optimized both at system level and subsystem definition. This novel method is based on the second principle of thermodynamics and the constructal law. It aims to produce a design process based on two steps. The first step aims producing a theoretical design of a system to reach energetic and operative optimization. The second aims to optimize the subcomponents of the system according the bottom up approach defined by constructal design optimization. A third step relating to the readiness against technology analysis is necessary to develop an effective industrial design. This method has named Constructal Design for Efficiency.

In this paper the authors, starting from the experience produced by the MAAT EU FP7, about the design of a cruiser-feeder and energy self sufficient airship for transport has produced the optimization of a medium altitude airship for transport, focused on the optimization of flying vehicle architecture to minimize by design the energy consumption during flight. The produced results allow defining a novel airship concept, which optimizes the airship shape to reach three fundamental energetic goals: energy consumption minimization; photovoltaic energy production maximization; definition of the conditions for energetically self-sufficient flight. The defined architecture can maximize the operative possibilities realizing an airship, which can ensure a point-to-point ground, based logistic models without any airport infrastructure with potential breakthrough impacts because of a better integration with any other terrestrial, maritime and aerial transport mode. Notwithstanding the use of hydrogen, it ensures an increased perception of safety by potential customers. It presents a safer ballooning architecture, without internal air ballonets, a cabin not directly attached to the bottom part of the balloon, which can be detached and piloted safely on the ground in case of serious accident during flight.
Investigation of Motion Control of Liner Axes and a Rotary Axis Under Constant Feed Speed Vector at Milling Point With a Five-Axis Machining Center
Authors: Maruyama Yuma , Akai Takayuki , Hirogaki Toshiki , Aoyama Eiichi , Ogawa Keiji
Published: April 2014

Recently, a novel manufacturing technology has spread out with a five-axis machining center. It is especially important to keep the surface roughness on an entire machined surface constant. Thus, we proposed a novel method for maintaining a constant feed speed vector at the cutting point between the end-mill tool and the workpiece surface by controlling two linear axes and a rotary axis with a five-axis machining center. In the present report, we focused on machining the combined inner and outer radius curvature and investigating the influence of synchronous control error between the linear axes and rotary axis on the machining accuracy and surface roughness. As a result, we determined that it is possible to suppress sudden change in the synchronous motion error by accurately aligning the motion direction of the linear and rotary axes and the feed speed vector at milling point at the contact point of the inner and outer circles.
Measurement and Simulation of Electric Power Consumption of Feed Drive Systems
Authors: Hayashi Akio , Sato Ryuta , Iwase Ryoma , Hashimoto Masayuki , Shirase Keiichi
Published: April 2014

In this study, in order to investigate the power consumption of feed drive system, a mathematical model to predict for the electric power consumption of feed drive systems is proposed by using the single-axis experimental apparatus. This can be driven by either of ball screw or linear motor and it is possible to change the mechanical properties of the machine such as grease viscosity of the table.

The power consumption is simulated by proposed simulation method based on the mathematical model of feed drive system and the simulated results are compared with the measured results of the experimental apparatus to confirm the validity of the simulated results.

In addition, it is clarified that the energy usages of the feed drive system. The energy losses of the feed drive system are divided into the loss of viscous friction, coulomb’s friction, servo amplifier, and motor. These energy losses are calculated by the proposed model. Then, it is investigated that the influence of the velocity and the friction to the power consumption of feed drive system experimentally.

As the results, it is confirmed that proposed simulation method can accurately predict the power consumption of the ball-screw feed drive system. It is also clarified that the friction energy loss of ball-screw drive is larger than one of linear motor drive, and the friction characteristics of linear guides influences the power consumption of linear motor drive system.
Impact of Bolt-Nut Interface Modeling Assumptions on the Calculated Low Cycle Fatigue Life of Aircraft Engine Turbine Rotor Bolted Joints
Authors: Saigal Anil , Jensen Luke , James Thomas
Published: April 2014

Finite element analysis is used extensively in the aircraft turbine engine industry to predict stresses to calculate low cycle fatigue (LCF) life of life-limited parts (LLP’s). A failure of an LLP can lead to a potentially catastrophic event such as a noncontainment of high energy debris. Under-predicted stress can cause the life limits to be set too high, which is a safety hazard. Over-predicted stress can cause the life limits to be set too low, which adds cost due to the need to replace expensive engine hardware more frequently. As such, high fidelity stress analysis is necessary to appropriately set LCF life limits. This study focuses on the nut-bolt interface modeling assumptions associated with a rotor bolted joint stress analysis for LCF predictions. A 3D finite element model of an actual aircraft engine rotor bolted joint is created. Different cases are analyzed and compared to investigate how the thread modeling assumptions might affect the calculated life in the mated rotor LLP hardware. Walker-adjusted alternating stress, σ0,alt, is used to measure the affect on life impact. It is shown that elastic versus elastic-plastic nut/bolt materials properties and the inclusion of the helical thread shape have minor impact on the calculated stresses. However, inclusion of contact elements with friction at the thread interface instead of couples has a moderate impact on the calculated stresses and therefore expected life.
Fabrication of Graphene Reinforced Aluminum Composite by Semi-Solid Processing
Authors: Bastwros Mina , Kim Gap-Yong , Zhang Kun , Wang Shiren
Published: April 2014

A composite made of graphene and aluminum is a promising material for many engineering applications due to its lightweight and relatively high strength properties. Unfortunately, the uniform dispersion of the graphene is considered one of the big challenges since the graphene clusters tend to deteriorate the mechanical properties of the composite. In this study, a graphene reinforced Al6061 composite has been investigated. The composites are fabricated by ball milling the graphene flakes and the Al6061 powder, followed by hot compaction in the semi-solid regime of the Al6061. In addition, a graphene reinforced composite with localized reinforced zones within the composite was also investigated The mechanical properties of the composites are measured by conducting a bend test, and microstructural analysis of the composite and fracture surfaces are performed. According to the bending test results, an enhancement in the strength is clearly observed.
Performance Evaluation on Cryogenic Cooling of Electrode in Electrical Discharge Machining in AISI D2 Steel
Authors: Kumar M. Pradeep , Kumar S. Vinoth
Published: April 2014

This research has been conducted to evaluate the performance of the Liquid Nitrogen (LN2) cooling of copper electrode in electrical discharge machining (EDM) on AISI D2 steel. The experimental process parameter such as discharge current, pulse on time and gap voltage were varied to explore their effects on machining performance, including the electrode wear and surface roughness. It was found that for electrode wear, discharge current, pulse on time, and gap voltage has the most significant effect, while the pulse on time and discharge current have the most significant effect on surface roughness. Analysis on the influence of cooling responses has been carried out and presented in this study. It was found that the electrode wear reduced up to 18% during LN2 cooling. Surface roughness was also significantly reduced while machining with LN2 electrode cooling. Scanning electron microscope (SEM) analysis was carried out to study the surface characteristics of machined surface. EDMed machined surface was also acceptable in LN2 cooling of the electrode.
Mechanical and Tribological Behavior of Alumina Nano Filler Reinforced Epoxy Hybrid Composites
Authors: Raghavendra Gujjala , Ojha Shakuntala , Acharya S. K. , Pal S. K.
Published: April 2014

Over the last few years, a number of researchers have been involved in investigating the exploitation of natural fibers as load bearing and wear resistance constituents in composite materials. The use of such materials in composites has increased due to their relative cheapness, ability to recycle and for the fact that they can compete well in terms of strength per weight of material. However still those materials not meeting the standards to replace the existing traditional filler composites. Nano composites are materials that are created by introducing nanoparticles into a microscopic sample material. This is part of the growing field of nanotechnology. The nano material tends to drastically add to the electrical and thermal conductivity as well as to the mechanical strength properties of the original material. A nano composite is the hybrid material consisting of a polymer matrix reinforced with a fiber, platelet, or particle having one dimension on the nanometer (nm) scale (10−9 m). So an attempt has been made in the present investigation to fabricate a new alumina nano jute-glass reinforced epoxy hybrid nano composite and studied the mechanical and tribological behaviour.
Characterization of Delamination in Laser Micro Transfer Printing
Authors: Al-okaily Ala’a , Ferreira Placid
Published: April 2014

Micro transfer printing is rapidly emerging as an effective method for heterogeneous materials integration. It transfers prefabricated micro- and nanoscale structures referred to as ‘inks’, from growth or fabrication donor substrates to functional receiver substrates. Laser Micro Transfer Printing (LMTP) is a laser-driven version of the micro transfer printing process, developed at the University of Illinois to enable non-contact release of the microstructure, thus making the transfer printing process independent of the properties or preparation of the receiving substrate. In this paper, an extensive study is conducted to investigate the capability of the LMTP process. Using square shaped silicon inks and polydimethylsiloxane (PDMS) stamps, and varying the lateral dimensions and thickness of the ink, the power absorption by the ink is measured to estimate the total energy stored in the ink-stamp system to initiate and propagate delamination at the interface. The delamination time for each size and thickness is experimentally observed at different laser beam powers using a high speed camera. Further, an axisymmetric thermo-mechanical FEM is developed to estimate the delamination temperatures at the interface utilizing the delamination time and power absorption for different ink sizes and thickness.
Advances in Direct Metal Deposition
Authors: Mazumder Jyoti , Song Lijun
Published: April 2014

Recently Additive Manufacturing (AM) has been hailed as the “third industrial revolution” by The Economist magazine [April-2012]. Precision of the product manufactured by AM largely depends on the on line process diagnostics and control. AM caters to the quest for a material to suit the service performance, which is almost as old as the human civilization. An enabling technology which can build, repair or reconfigure components layer by layer or even pixel by pixel with appropriate materials to match the performance will enhance the productivity and thus reduce energy consumption. With the globalization, “Economic Space” for an organization is now spreads all across the globe. The promise of AM for Global Platform for precision additive manufacturing largely depends on the speed and accuracy of in-situ optical diagnostics and its capability to integrate with the process control. The two main groups of AM are powder bed (e.g. Laser Sintering) and pneumatically delivered powder (e.g. Direct Metal Deposition [DMD]) to fabricate components. DMD has closed loop capability, which enables better dimension and thermal cycle control. This enables one to deposit different material at different pixels with a given height directly from a CAD drawing. The feed back loop also controls the thermal cycle. New optical Sensors are either developed or being developed to control geometry using imaging, cooling rate by monitoring temperature, microstructure, temperature and composition using optical spectra. Ultimately these sensors will enable one to “Certify as you Build”. Flexibility of the process is enormous and essentially it is an enabling technology to materialize many a design. Several cases will be discussed to demonstrate the additional capabilities possible with the new sensors. Conceptually one can seat in Singapore and fabricate in Shanghai. Such systems will be a natural choice for a Global “Economic Space”.
Effect of Bonding Pressure on Joint Formation by Diffusion Bonding of Ti-6Al-4V and Mg-AZ31
Authors: Atieh Anas M. , Khan Tahir I.
Published: April 2014

Magnesium is the lightest structural metal and recently magnesium and its alloys have received increased attention in various engineering applications. Titanium is a light metal and shows excellent corrosion resistance and high specific strength. The ability to join these two metals together can increase their use in the automotive and aerospace industries. However, differences in the physical properties of these alloys (e.g. melting point for Ti-6Al-4V is 1650°C and 680°C for AZ31) make the joining of these dissimilar alloys a great challenge. This research work presents the effect of one of the most important parameters in diffusion bonding; the bonding pressure. Optimizing bonding parameters resulted in sound joint with homogeneous microstructure and suitable mechanical properties. To join these two alloys the diffusion bonding was carried out using thin (20μm) pure Ni foils at different bonding pressures (0.2 and 0.7 MPa) at 515°C as a function of holding time of 5 to 30 minutes. The results showed a direct relation exist between bonding pressure, joint microstructure and mechanical properties. Reaction zones were identified inside bonding region and tested with respect to hardness profile. In case of 0.2 MPa pressure the joint width increased from 86μm for bonding time of 5 minutes to 197μm for 20 minutes. A decrease in joint width to 144μm at bonding time of 30 minutes shows that isothermal solidification starts for a bonding time of 20 minutes. However, when bonding at 0.7 MPa pressure the joint width increased from 59 μm for bonding time of 5 minutes to 156 μm at 10 minutes. A decrease to 123 μm at bonding time of 20 minutes was recorded. Even further decrease to 75 μm at bonding time of 30 minutes was noticed. This suggest Isothermal solidification takes place in case of 0.7 MPa earlier than in case of 0.2 MPa.
Prediction of Ablation Rates From Solid Surfaces Exposed to High Temperature Gas Flow
Authors: Akyuzlu Kazim M. , Coote David
Published: April 2014

A mathematical model and a solution algorithm is developed to study the physics of high temperature heat transfer and material ablation and identify the problems associated with the flow of hydrogen gas at very high temperatures and velocities through pipes and various components of Nuclear Thermal Rocket (NTR) motors. Ablation and melting can be experienced when the inner solid surface of the cooling channels and the diverging-converging nozzle of a Nuclear Thermal Rocket (NTR) motor is exposed to hydrogen gas flow at temperatures around 2500 degrees Kelvin and pressures around 3.4 MPa. In the experiments conducted on typical NTR motors developed in 1960s, degradation of the cooling channel material (cracking in the nuclear fuel element cladding) and in some instances melting of the core was observed. This paper presents the results of a preliminary study based on two types of physics based mathematical models that were developed to simulate the thermal-hydrodynamic conditions that lead to ablation of the solid surface of a stainless steel pipe exposed to high temperature hydrogen gas near sonic velocities. One of the proposed models is one-dimensional and assumes the gas flow to be unsteady, compressible and viscous. An in-house computer code was developed to solve the conservations equations of this model using a second-order accurate finite-difference technique. The second model assumes the flow to be three-dimensional, unsteady, compressible and viscous. A commercial CFD code (Fluent) was used to solve the later model equations. Both models assume the thermodynamic and transport properties of the hydrogen gas to be temperature dependent. In the solution algorithm developed for this study, the unsteady temperature of the pipe is determined from the heat equation for the solid. The solid-gas interface temperature is determined from an energy balance at the interface which includes heat transfer from or to the interface by conduction, convection, radiation, and ablation. Two different ablation models are proposed to determine the heat loss from the solid surface due to the ablation of the solid material. Both of them are physics based. Various numerical simulations were carried out using both models to predict the temperature distribution in the solid and in the gas flow, and then predict the ablation rates at a typical NTR motor hydrogen gas temperature and pressure. Solid mass loss rate per foot of a pipe was also calculated from these predictions. The results are presented for fully developed turbulent flow conditions in a sample SS pipe with a 6 inch diameter.
Sensitivity Analysis of the Factors Affecting Force Generation by Wing Flapping Motion
Authors: Rege Alok A. , Dennis Brian H. , Subbarao Kamesh
Published: April 2014

Insect flight comes with lot of intricacies that cannot be explained by conventional aerodynamics. Insects rely on a peculiar high frequency wing flapping mechanism to produce the aerodynamic forces required for sustainable flight. Broad study of this mechanism for producing forces is imperative to attain a reasonably accurate representation of these forces. In this research, sensitivity analysis is performed on the factors governing the aerodynamic force production due to flapping motion of a two-dimensional wing section of a Micro Air Vehicle (MAV). Published results obtained on a wing section of an MAV model by the authors in their previous work are used for preliminary review. The flapping path parameters are nondimensionalized and the moving mesh problem is solved in a numerical flow solver. A thorough sensitivity analysis is done to realize the effects of the flapping wing Reynolds number, Strouhal number, and the absolute angle of attack on the force generation.
The Relationship Between Surface Roughness and Corrosion
Authors: Toloei Alisina , Stoilov Vesselin , Northwood Derek
Published: April 2014

There are different parameters which can affect electrochemical reactions such as type of electrolyte, velocity, temperature, oxidizing agents, impurities, anode material type and surface treatment. It has been shown that pre-treatment of working electrode (anode) through abrasion techniques is one of the most important parameters affecting on Tafel slopes and consequently corrosion rate. Surface roughness of the metal surface is a major influence on general corrosion, nucleation of metastable pitting and pitting potential as well.

In this study different surface roughnesses were created on nickel surface by SiC papers and corrosion properties were compared. Electrochemical impedance spectroscopy (EIS) and profilometry tests were carried out on all the samples and the results were compared with another sample prepared through laser ablation method. Corrosion rate values were calculated and were compared with EIS results for all the samples and a trend in the effect of roughness on corrosion protection of nickel was introduced. SEM and 3D roughness images were taken and compared for all of the samples before and after corrosion tests. Different mechanisms were distinguished for samples created through different methods. The lower the roughness values, the more the corrosion resistance. Sample with patterns created through laser ablation method showed the best protection properties compared to other samples.
Near Minimum Material Zone: A New Concept to Reduce the Weight of the Aircraft Components in Machining Using Lean Six Sigma Methodology
Authors: Nithyanandam Ganesh Kumar , Franchetti Matthew , Pezhinkattil Radhakrishnan
Published: April 2014

A component in machining is accepted when the dimensions are within the tolerance specifications. In aircraft components machining, controlling the weight of the components is of high importance. In this paper, a new concept called near minimum material zone was introduced, which would address the control of the weight of the aircraft components in machining. To prove this concept, two sets of experiments with 20 samples were conducted using Deckel Maho CTX310 ECO VI CNC machine. The first experiment was conducted with normal machining processes. The second experiment was conducted using a new concept. Lean Six Sigma DMAIC methodology was adopted for this study. Several Six Sigma tools such as process capability analysis (Cp, Cpk), cause and effect diagram, X Hi/Lo and R-charts, etc. were used. The paper suggests that this new concept not only helped to control the weight of the aircraft components but also improved the desired quality by minimizing the dispersion of the component dimensions to obtain higher sigma level.
Numerical Simulation of a Hydrogen Fueled Scramjet Combustor at Mach 1.5 Using Strut Injectors at Mach 2.47 Air Speed
Authors: Pandey K. M. , Nath Binita
Published: April 2014

In the arena of design of combustion chamber of scramjet engine lots of development are still going on. A properly designed combustor shall promote sufficient mixing of the fuel and air so that the desired chemical reaction and thus heat release can occur within the limited residence time of the fuel-air mixture. In the present work two different types of strut fuel injectors are investigated numerically, strut with circular injector and strut with alternating wedge injector. The combustor and strut dimensions are same as DLR Scramjet model. It consists of a divergent channel with a flame–holding, wedge shaped structure in the middle of the flow field from the base of which hydrogen is injected. Comparative study of mixing and combustion enhancement has been performed for Mach number 2.47 for air and Fuel (hydrogen) is injected at Mach 1.5.Simulations have been performed using ANSYS14-FLUENT. Density based approach is chosen and Standard k-ε model is used for modeling turbulence and single step finite rate chemistry is used for modeling the H2-Air kinetics. k-ε model is based on a finite volume discretization of the continuity, momentum, energy equations. Dirichlet and Neumann boundary conditions are applied at inflow and outflow boundary conditions respectively and fixed walls are subjected to no slip conditions. For the purpose of validation, the k-ε results are compared with experimental data. The numerically predicted profiles of static pressure, axial velocity, turbulent kinetic energy and static temperature are compared for each model. It is seen that due to combustion the recirculation region behind the wedge becomes larger and acts as a flame holder for the hydrogen diffusion flame. The leading edge shock reflected off the upper and lower combustor walls makes the setting of combustion when it hits the wake in a region where large portions of the injected fuel have been mixed up with the air. The shear layers at the base of the wedge becomes more pronounced due to the fact that continuous ignition occurs within these shear layers. Maximum temperature occurred at the recirculation area which is produced due to shock wave-expansion, wave jet interaction and fuel jet losses concentration. It was found that mixing and combustion was considerably better with the more flow-disturbing alternating wedge injector strut and the rise in static temperature is enhanced with higher Mach number of air.
A Comparison of Continuum, DSMC and Free Molecular Modeling Techniques for Physical Vapor Deposition
Authors: Gott Kevin , Kulkarni Anil , Singh Jogender
Published: April 2014

Advanced Physical Vapor Deposition (PVD) techniques are available that produce thin-film coatings with adaptive nano-structure and nano-chemistry. However, such components are manufactured through trial-and-error methods or in repeated small increments due to a lack of adequate knowledge of the underlying physics. Successful computational modeling of PVD technologies would allow coatings to be designed before fabrication, substantially improving manufacturing potential and efficiency.

Previous PVD modeling efforts have utilized three different physical models depending on the expected manufacturing pressure: continuum mechanics for high pressure flows, Direct Simulation Monte Carlo (DSMC) modeling for intermediate pressure flows or free-molecular (FM) dynamics for low pressure flows. However, preliminary calculations of the evaporation process have shown that a multi-physics fluidic solver that includes all three models may be required to accurately simulate PVD coating processes. This is due to the high vacuum and intermolecular forces present in vapor metals which cause a dense continuum region to form immediately after evaporation and expands to a rarefied region before depositing on the target surface.

This paper seeks to understand the effect flow regime selection has on the predicted deposition profile of PVD processes. The model is based on experiments performed at the Electron-Beam PVD (EB-PVD) laboratory at the Applied Research Lab at Penn State. CFD, DSMC and FM models are separately used to simulate a coating process and the deposition profiles are compared. The mass deposition rates and overall flow fields of each model are compared to determine if the underlying physics significantly alter the predicted coating profile. Conclusions are drawn on the appropriate selection of fluid physics for future PVD simulations.