bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPARISON OF CLOSED-FORM SOLUTIONS FOR THE LUCAS-UZAWA MODEL VIA THE PARTIAL HAMILTONIAN APPROACH AND THE CLASSICAL APPROACH
Authors: Naz Rehana , Chaudhry Azam
Published: July 2017

In this paper we derive the closed-form solutions for the Lucas-Uzawa growth model with the aid of the partial Hamiltonian approach and then compare our results with those derived in literature. The partial Hamiltonian approach provides two first integrals [9] in the case where there are no parameter restrictions and these two first integrals are utilized to construct three sets of closed form solutions for all the variables in the model. We begin by using the two first integrals to find two closed form solutions, one of which is new to the literature. We then use only one of the first integrals to derive a third solution that is the same as that found in the previous literature. We continue by analyzing the newly derived solution in detail also show that all three solutions converge to the same long run balanced growth path. The special case when the share of capital is equal to the inverse of the intertemporal elasticity of substitution is also investigated in detail.
SOLVABILITY OF A CLASS OF N -TH ORDER LINEAR FOCAL PROBLEMS
Authors: Almenar Pedro , Jodar Lucas
Published: July 2017

This paper presents a recursive method which yields necessary and sufficient conditions for the existence of solutions of a class of n-th order linear focal boundary value problems in the interior of a given interval, in the form of integral inequalities. Some results on the sign of the derivatives of the Green functions of n-th order linear focal boundary value problems will also be provided.
CORDIAL VOLTERRA INTEGRAL EQUATIONS AND SINGULAR FRACTIONAL INTEGRO-DIFFERENTIAL EQUATIONS IN SPACES OF ANALYTIC FUNCTIONS∗
Authors: Kangro Urve
Published: July 2017

We study general cordial Volterra integral equations of the second kind and certain singular fractional integro-differential equation in spaces of analytic functions. We characterize properties of the cordial Volterra integral operator in these spaces, including compactness and describe its spectrum. This enables us to obtain conditions under which these equations have a unique analytic solution. We also consider approximate solution of these equations and prove exponential convergence of approximate solutions to the exact solution.
Is There a Disk of Satellites around the Milky Way?
Authors: Maji Moupiya , Zhu Qirong , Marinacci Federico , Li Yuexing
Published: July 2017

The “disk of satellites” (DoS) around the Milky Way is a highly debated topic with conflicting interpretations of observations and their theoretical models. We perform a comprehensive analysis of all of the dwarfs detected in the Milky Way and find that the DoS structure depends strongly on the plane identification method and the sample size. In particular, we demonstrate that a small sample size can artificially produce a highly anisotropic spatial distribution and a strong clustering of the angular momentum of the satellites. Moreover, we calculate the evolution of the 11 classical satellites with proper motion measurements and find that the thin DoS in which they currently reside is transient. Furthermore, we analyze two cosmological simulations using the same initial conditions of a Milky-Way-sized galaxy, an N-body run with dark matter only, and a hydrodynamic one with both baryonic and dark matter, and find that the hydrodynamic simulation produces a more anisotropic distribution of satellites than the N-body one. Our results suggest that an anisotropic distribution of satellites in galaxies can originate from baryonic processes in the hierarchical structure formation model, but the claimed highly flattened, coherently rotating DoS of the Milky Way may be biased by the small-number selection effect. These findings may help resolve the contradictory claims of DoS in galaxies and the discrepancy among numerical simulations.
Geometrically Thick Obscuration by Radiation-driven Outflow from Magnetized Tori of Active Galactic Nuclei
Authors: Chan Chi-Ho , Krolik Julian H.
Published: July 2017

Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This “steady” state lasts for as long as there is gas resupply toward the inner edge. The torus is best described as a midplane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three-quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.
The JCMT Transient Survey: Data Reduction and Calibration Methods
Authors: Mairs Steve , Lane James , Johnstone Doug , Kirk Helen , Lacaille Kevin , Bower Geoffrey C. , Bell Graham S. , Graves Sarah , Chapman Scott ,   The JCMT Transient Team
Published: July 2017

Though there has been a significant amount of work investigating the early stages of low-mass star formation in recent years, the evolution of the mass assembly rate onto the central protostar remains largely unconstrained. Examining in depth the variation in this rate is critical to understanding the physics of star formation. Instabilities in the outer and inner circumstellar disk can lead to episodic outbursts. Observing these brightness variations at infrared or submillimeter wavelengths constrains the current accretion models. The JCMT Transient Survey is a three-year project dedicated to studying the continuum variability of deeply embedded protostars in eight nearby star-forming regions at a one-month cadence. We use the SCUBA-2 instrument to simultaneously observe these regions at wavelengths of 450 and 850 μm. In this paper, we present the data reduction techniques, image alignment procedures, and relative flux calibration methods for 850 μm data. We compare the properties and locations of bright, compact emission sources fitted with Gaussians over time. Doing so, we achieve a spatial alignment of better than 1″ between the repeated observations and an uncertainty of 2%–3% in the relative peak brightness of significant, localized emission. This combination of imaging performance is unprecedented in ground-based, single-dish submillimeter observations. Finally, we identify a few sources that show possible and confirmed brightness variations. These sources will be closely monitored and presented in further detail in additional studies throughout the duration of the survey.
Reducing Falls After Electroconvulsive Therapy: A Quality Improvement Project
Authors: Brown Allana Marie
Published: July 2017

Falls after electroconvulsive therapy (ECT) in patients 60 and older have been long recognized as a major clinical care issue across many mental health care settings. The evidence base for fall prevention strategies after receiving ECT is sparse. The risk factors for falls after ECT are vast and complex in nature, especially considering existing comorbid medical conditions. The dearth of research in guiding practitioners on fall reduction interventions for this patient population illuminates a gap in mental health care quality and safety. The purpose of the current nurse-led quality improvement project was to reduce falls in patients undergoing ECT by enhancing safety measures through education and a post-ECT treatment protocol. The project did not prove to be as efficacious as anticipated as measured by fall rate outcomes. Several factors that may account for the project's findings are discussed. [
Journal of Psychosocial Nursing and Mental Health Services, 55
(7), 20–29.]
Perspectives of Individuals With Mental Illness on Community Mental Health Services in China: A Qualitative Exploration
Authors: Xiao Lin , Gao Yulin , Zhang Lili , Sun Xiaojia , Zeng Kai
Published: July 2017

Little is known about the perspectives of individuals with mental illness on community mental health services (CMHS) in China. The current study aimed to explore these perspectives. Semi-structured interviews were completed with a purposive sample of 25 individuals with mental illness recruited from three communities in Guangzhou City, China. The Colaizzi method was used for data analysis. Three main themes were identified: (a)
patients' perceptions of CMHS
, (b)
patients' barriers to accessing CMHS
, and (c)
patients' expectations of CMHS
. The identified issues should be taken into consideration in improving CMHS. CMHS staff, including nurses, should make patients more aware of CMHS. To increase CMHS use and make it more responsive to patients' expectations, staff should try to resolve patients' stigma and desire to return to society. [
Journal of Psychosocial Nursing and Mental Health Services
,
55
(7), 30–37.]
El hormigón armado en Cataluña (1898-1929): cuatro empresas y su relación con la arquitectura
Authors: Graus R. , Martín Nieva H. , Rosell J.
Published: July 2017

Entre 1898 y 1929 se desarrollaron en Cataluña variadas iniciativas empresariales que introdujeron el hormigón armado en la arquitectura. En el artículo se estudian las empresas Anónima Claudio Duran - Construcciones Monier, Marial Hermanos - Sociedad Colectiva, Construcciones y Pavimentos, S. A., y Material y Obras, S. A. Se propone una aproximación al entramado productivo que estudie las empresas, sus técnicos y sus obras en toda su complejidad con la intención de valorar cómo el hormigón armado transformó el sector de la construcción, con nuevas empresas de otra escala productiva. Sin embargo, el ciclo económico depresivo 1929-1952 lastró estas iniciativas y alargó artificialmente los restos de la tradicional «construcción catalana».
Le défi de la différenciation géographique, ou l’Europe à l’épreuve de ses diversités
Authors: Rey Violette
Published: July 2017

Diversity and differences are reckoned to be among Europe’s defining characteristics, nearly by-words for its uniqueness, being at the same time assets and challenges for the construction of an enlarged European Union. By taking concepts as a starting point, the text tries to offer an analysis of the processes of diversification and differentiation without reference to any essentialism ; diversity and difference being relativized based on the scale at which they arise. Differentiation based on hard and enduring geographical partition lines (fractures), is analysed as a process in which identity-formation is heavily implicated, and in which complementarity and interrelationships between neighbouring cultural spheres are lacking. When differentiation is expressed by a continuum however, it is analysed as a process of interaction and interdependence, representing the mobility characteristic of economic development. The contemporary challenge derives from the risk of superposing these two types of differentiation, which would amount to being a stubborn obstacle to European integration.
De l’identité-monument à l’identité-événement : un passage impossible ?
Authors: Mihali Ciprian
Published: July 2017

Based on the commentary of Michel Foucault, Michel de Certeau and Koselleck, the author thinks about the space “crystallizing” the identitary memories of post-communist societies. The monument and the event are the two metaphors underlying these reflections.The monument is not a mere building. It is understood both as organizing space and as a relationship to the space instituted by a hierarchical power. The monument conjures up a sense of unity and homogeneity whereby the individual and the community alike are assured and reassured in times of identity crisis. It is grounded in a pre-modern logic that affords the individual neither autonomy, nor the ability to provide himself with his own law of thought and action.The event is grounded in a modern, if not post-modern, logic. An event occurs in a heterogenous space, shaped by thousands of concurrent powers busy creating the multiple spaces where daily practices eventualize identity in diversity, i. e. bringing the unitary image of the city-monument down to echo on the level of the ordinary individual.Because it is conflictingly affected by a sense of nationalism generating caricatural monumentality, and by an eagerness to consume, which produces thousands of minor monuments, the Romanian city of Cluj, in Romania, shall serve as the background to this reflection.
La gestion des différences dans les pays nordiques : une réflexion à partir du cas de la Suède
Authors: Sanders Lena
Published: July 2017

In Nordic countries, erasing social differences is part of a long traditional process characterised by firm political will and strong social control. The analysis of the Swedish model, through the crisis of the 1990s, brings out three dimensions of this management of differences : the rise of gender parity, the treatment of immigrants, and the decentralisation of territorial management. This analysis stresses, on the one hand, the processes of diversification and the irrepressible emergence of new types of differences. On the other hand, it proposes which kinds of adjustment can allow for the self-maintenance of this model so as to pursue the goal of equality. In spite of strong cultural and socio-economical similarities shared within a common Nordic identity, Scandinavian countries did not exhibit common foreign policy towards the European Union, each of them joining the EU upon a personal initiative, at different times and after a great deal of hesitation. When one feels completely European, is it necessary to belong to this EU “machine” for anything other than pragmatic or economic reasons ?
Berlin et la question de la centralité culturelle en Allemagne
Authors: Grésillon Boris
Published: July 2017

Since political and cultural central functions are intimately interrelated, Berlin got a new prominent cultural status in Germany when it recovered its role of capital city. In Berlin, the recovered cultural centrality is a cause of differentiation, and even of exception in a deeply federal country. Yet, it also disturbs the local cultural landscape. The federal and polycentric German model, perfectly carried out in cultural life, may be reconsidered and transformed in favour of a more centralised and hierarchic system with Berlin at its head. Beyond the issue of Berlin as a cultural main city, the opposition between federalism and centralising trends is highlighted.
Système de villes et niveaux d’identification territoriale en Roumanie
Authors: Groza Octavian
Published: July 2017

The author focuses on the role played by the Rumanian urban system in the emergence of modern behaviours – at individual, collective and/or community levels – as well as on the role played by changing territorial organizations. His analysis refers explicitly to the post-modern paradigm, when he suggests that the obstacles to development which have become apparent in Romania are due to a weak acceptance of the value of otherness.
Cultural facilities and urban development: WIELS contemporary art centre and the transformation of a working-class neighbourhood
Authors: Debersaques Simon
Published: July 2017

The opening in 2007 of the first contemporary art centre in Brussels in the lower part of the municipality of Forest, which is characterised by an industrial urban fabric and socioeconomic insecurity, seems to have marked a new era for this neighbourhood. WIELS defines itself as “an international laboratory for the creation and diffusion of contemporary art”. Using a typology based on international literature, the objective of the study is to confront the rationale behind the creation of this cultural institution with the social and spatial transformations which have taken place in the neighbourhood since its establishment. In this article, we attempt to understand how WIELS contributes to urban development through culture. By combining different qualitative methods, it is clear that although WIELS was initially caught in a conflict between property income and openness towards its neighbourhood, certain tangible and discursive elements might prompt us to consider WIELS as one of the components in the formation of a new creative metropolitan centrality.
El Padre João Pedro Gay (1815-1891) y su contribución a la historia social del guaraní de Corrientes
Authors: Obermeier Franz , Cerno Leonardo
Published: July 2017

Este trabajo destaca la figura del clérigo francés João Pedro Gay (1815-1891) como referente de la investigación lingüística del guaraní en el siglo XIX, tomando como base una copia de un poema en guaraní hecha por el propio clérigo en 1867. El poema, publicado en el diario Eco de Corrientes, constituye un antecedente del guaraní correntino del siglo XIX y representa a su vez una pequeña porción de lo que podría ser el legado de Gay como investigador e historiador del guaraní. En este sentido ofrecemos una interpretación del texto teniendo en cuenta el contexto histórico y sociolingüístico en que se enmarca, el cual incluye la Guerra de la Triple Alianza y las diferentes políticas lingüísticas y representaciones sociales que se desarrollaban en aquel tiempo en torno al guaraní. Por último concluimos valorando el documento de Gay como una importante contribución a nuestro conocimiento de la historia del guaraní y sus variedades en la región.
El Archivo Documental, Administrativo e Histórico de la Administración de Parques Nacionales en el Museo de la Patagonia “Dr. Francisco P. Moreno”
Authors: Piantoni Giulietta , Pupio María Alejandra
Published: July 2017

Los objetos, para constituirse en objetos científicos, requirieron de su transformación en papel. La práctica de la ciencia como se la conoce hasta ahora no existiría sin el papel que favoreció el intercambio y circulación de objetos, ideas y libros, la formación de colecciones y sus catálogos, el registro del trabajo de campo, la instrucción a los observadores y la obtención de sus respuestas. Gracias al corpus de documentos que ha sobrevivido, hoy se pueden reconstruir historias institucionales, pero también las redes de sociabilidad científica, incluyendo la relación entre los profesores, los corresponsales y los comerciantes de objetos de historia natural.Con el objetivo de relevar el Archivo Documental, Administrativo e Histórico de la Administración de Parques Nacionales en el Museo de la Patagonia “Dr. Francisco P. Moreno”, este trabajo propone un recorrido por la historia de la institución, un breve estado de la cuestión, sus desafíos y oportunidades.
Processus de reconversion professionnelle de travailleur.euse.s inscrit.e.s dans des parcours professionnels marqués par la mobilité : entre le deuil du métier et le désir de réinvestir sa vie autrement
Authors: Fournier Geneviève , Gauthier Christine , Perron Frédéric , Masdonati Jonas , Zimmermann Hélène , Lachance Lise
Published: July 2017

Cet article vise à mieux comprendre comment se construit le processus de reconversion professionnelle à la lumière de l’enchaînement des événements professionnels et biographiques de travailleur.euse.s du Québec. S’appuyant sur le paradigme du parcours de vie, l’analyse des entretiens menés auprès de 34 participant.e.s inscrit.e.s dans des parcours professionnels marqués par la mobilité a permis d’identifier, sur un horizon temporel de dix ans, quatre processus-types de reconversion : deux plus particulièrement impulsés par le contexte – le marché du travail ou la vie personnelle – et deux autres, davantage impulsés par des motifs identitaires.
Influence of manure concentration as inoculum in anaerobic digestion of vinasse
Authors: Silva Carlos Eduardo de Farias , Abud Ana Karla de Souza
Published: July 2017

Vinasse, main residue of the sugarcane industry, has high pollutant content, being subjected to the use in biogas production due to the high content of organic matter non-toxic to microbial action. For a consolidated process, it is necessary to study parameters that influence the process, in which the amount of inoculum is one of the major factors in the biological process of biogas production. This study investigated the influence of the amount of manure as inoculum (0.5 to 5.5%) during the biodigestion process, evaluating variables such as chemical oxygen demand (COD), pH, biogas production, methane concentration, total solids and total phosphorus and nitrogen contents, as well as microbiological analysis in the sludge remaining in the digester. Biodigestion occurred normally, with hydraulic retention time (HRT) of 20 days, with an acidogenic phase, subsequent stabilization of pH and biogas production. The vinasse had COD and total solids reduced during biodigestion by around 67 and 40%, respectively. Biogas production was increased after the fifth day. Among the three studied conditions, there was no significant increase in efficiency of inoculum use and it can be used the lowest amount, 0.5 % (m v-1).
Screening of whole yeast free-cells and optimization of pH and temperature for fructooligosaccharides production
Authors: Deffert Flávia , Agustini Bruna Carla , Picheth Geraldo , Bonfim Tania Maria Bordin
Published: July 2017

Fructooligosaccharides are catalyzed by β–fructofuranosidase enzyme, produced by many microorganisms. However, in order to achieve a more profitable, low time-consuming process with lower cost, researchers have sought alternatives. This study aimed to select and identify yeasts able to produce fructooligosaccharides and evaluate the influence of pH and temperature on their synthesis. Yeast suspensions, solutions of 500 g L-1 sucrose and three values of pH (4.5, 5.5, and 6.5) and temperature (40, 50, and 60ºC) were tested. Yeast species were identified by molecular techniques. Among 141 yeast isolates from grapes, 65 were able to synthesize fructooligosaccharides. The maximum concentration of fructooligosaccharides was 4.8% (w v-1), and Saccharomyces cerevisiae 222 produced 1-kestose and nystose.
Parametric Optimization of CNC End Milling Process on Aluminium 6063 Alloy Using Grey Based Taguchi Method
Authors: Hussain Md Ashfaq , Prasad K.K. , Jadhav Anil S. , Biradar Gangadhar
Published: July 2017

This investigation focused on the multi-response optimization of CNC end milling of Aluminium 6063 Alloy material using Grey relational analysis and Taguchi method. Experiments were designed based on L9 Taguchi Orthogonal array, to arrive at an optimum parameter combination within the experimental domain. The spindle speed (S), feed rate (f) and depth of cut (d) which are known to have considerable effect on the selected responses i.e. surface roughness (Ra) and Material removal rate (MRR) and are considered as control parameters. The single objective optimization using Taguchi method more often results in conflicting requirements on control variables. To overcome this challenge, the Taguchi approach followed by Grey relational analysis was applied to solve this multi response optimization problem. The significance of these factors on overall quality characteristics of the milling process has also been evaluated quantitatively with the Analysis of variance method (ANOVA). Optimal results were verified through confirmation experiments. This shows feasibility of the Grey relation analysis in combination with Taguchi technique for continuous improvement in product quality in manufacturing industry and the suitability of the method to optimize the multi objective problems involved in CNC milling.
Performance Evaluation of PVD and CVD Coated Inserts during End Milling with DRY and MQL Condition
Authors: Srivastava Isha , Batish Ajay
Published: July 2017

The aim of this study were to evaluate the performance of PVD (TiAlN+TiN) and CVD (TiCN+Al2O3+TiN) coated inserts in end milling of EN–31 hardened die steel of 43±1 HRC during dry and MQL (Minimum quantity lubrication) machining. The experiments were conducted at a fixed feed rate, depth of cut and varying cutting speed to measure the effect of cutting speed on cutting force and tool wear of CVD and PVD-coated inserts. The performance of CVD and PVD-coated inserts under dry and MQL condition by measuring the tool wear and cutting force were compared. During cutting operation, it was noticed that PVD inserts provide less cutting force and tool wear as compared to the CVD inserts under both dry as well as the MQL condition because PVD inserts have a thin insert coating and CVD inserts have a thick insert coating, but PVD inserts experience catastrophic failure during cutting operation whereas CVD inserts have a capability for continuous machining under different machining. Tool wear has measured by SEM analysis. The result shows that MQL machining provides the optimum results as compared to the dry condition. MQL machining has the ability to work under high cutting speed. As the cutting speed increases the performance of dry machining was decreased, but in MQL machining, the performance of the inserts was increased with increases of cutting speed. MQL machining generates less cutting force on the cutting zone and reduces the tool wear which further increase the tool life.
Parametric Investigations on Surface Roughness of Hard Turned AISI 52100 Steel
Authors: Ravi Sankar B. , Umamaheswarrao P. , Sharief Shaik Nawaz , Suresh T. , Raju Rayudu
Published: July 2017

The present work is aimed to investigate the effect of the turning parameters on the surface roughness produced during hard turning of AISI 52100 bearing steel with PCBN cutting tools. The experiments are devised using Taguchi L27 orthogonal array and analysis is carried out using MINITAB 14 software. The influence of individual parameters is discussed with main effects plot and the combined parametric effect is presented with interaction effects plot. From the results it is observed that speed and nose radius has a great influence on surface roughness. The interaction effect is significant for speed and feed combination.
Experimental Investigation of Single Point Incremental Forming of Aluminum Sheet in Groove Test
Authors: Sharma Vikrant , Gohil Ashish , Modi Bharat
Published: July 2017

Incremental sheet forming is one of the latest processes in sheet metal forming industry which has drawn attention of various researchers. It has shown improved formability compared to stamping process. Single Point Incremental Forming (SPIF) process requires only hemispherical tool and no die is required hence, it is a die-less forming process. In this paper experimental investigation on SPIF for Aluminium sheet has been presented. A groove test on Vertical Machining Centre has been performed. Factors (Step depth, Blank holder clamping area, Backing plate radius, Program strategy, Feed rate and Tool diameter) affecting the process are identified and experiments are carried out using fractional factorial design of experiments. Effect of the factors on fractured depth, forming time and surface finish have been analyzed using Minitab 17 software.
Stiffness Analysis of Inverted Tripod Parallel Manipulator
Authors: Geethapriyan T. , Manoj Samson R. , Muthuramalingam T. , Arun Raj A.C.
Published: July 2017

The concept of parallel manipulator is becoming more popular in modern manufacturing processes due to its various inherent advantages like rigidity, less inertia and accuracy. This project focuses on modeling, simulation and dynamic analysis of inverted tripod parallel manipulator which has three degree of freedom (1 transverse in z axis and rotation motion in x and y axis). The Stewart Gough parallel manipulator consists of moving platform connected to fixed platform with six links (6 Degree of Freedom).This inverted tripod parallel manipulator consists of movable platform connected to the fixed platform with only three links so it has better rigidity compared to Stewart Gough platform. The Stewart Gough parallel manipulator is considered to be highly stable because moving platform size is smaller than the fixed platform. Inverted type parallel manipulator consists of moving platform bigger than the fixed platform. So to improve the stiffness and precision ball screw is used for the support of links. The design of parallel manipulator is done considering rigidity, strength and efficiency of the system. The modeling of the tripod manipulator is done using PRO-E software. Kinematic analysis has been carried out and the stiffness analysis will be done by using ANSYS and ADAMS software.
Finite Element Analysis of Aluminium Based Composite as a Material for Connecting Rod
Authors: Nandish B. , Muthanna K.P. , Kaveriappa M.B.
Published: July 2017

Connecting Rod is a link between Piston and Crank. It is meant to transfer combustion forces from the Piston to Crank. In the present work an Aluminium based metal matrix composite is proposed as a material for Connecting Rod. Composition of the proposed material is Aluminium 6061-9%Silicon carbide-15% fly ash. Model of a Connecting Rod is designed and stress analysis is done using Finite Element Analysis. Proposed material is compared with an existing Connecting Rod material Aluminium-360. Parameters like von-misses stress, von-misses strain, deformation, factor of safety and weight reduction were calculated. From the comparison proposed material is found to be 26.11 % lesser weight, more stiffer by 7.21 %, shows improved factor of safety and can sustain higher stress.
GETSLOCK-Advanced Front Closure Design for Multi-Tube Hairpin Heat-Exchanger
Authors: Babu Libin , Anugraha Vaishak K. , Babu Alby
Published: July 2017

GETS lock is a modified front closure for hairpin heat exchanger with newly introduced characteristics like full ring, split locking ring and the slope on the tube sleeve.
Analysis of Physical and Mechanical Properties of A3003 Aluminum Honeycomb Core Sandwich Panels
Authors: Rajkumar S. , Arulmurugan B. , Manikandan M. , Karthick R. , Kaviprasath S.
Published: July 2017

The demand for lightweight structures made of sandwich panels is ever increasing in many Industrial sectors. Numerous research efforts have been taken by various researchers in this area in terms of weight and cost reduction. Sandwich panel is a composite structure and it is an excellent alternative material in place of weight reduction without sacrificing its strength and stiffness characteristics. The geometrical characteristics of honeycomb core sandwich panels as well as their physical and mechanical properties such as compressive strength, flexural stiffness, core shear moduli, shear strength and stiffness are analyzed. The sandwich panels are available in various shapes and sizes to the service requirement. The commercially available sandwich panels have different core materials such as foams, FRPs and metallic and non metallic materials. The structure of the core typically varies as truss type and honeycomb. The face sheets and the core materials are bonded using thermo-set resins.
Application of Tubercles in Wind Turbine Blades: A Review
Authors: Kumar Vivek V. , Shah Dilip A.
Published: July 2017

Due to the rapid depletion of conventional energy resources like fossil fuels and their harmful effects on the environment, there is an urgent need to seek alternative and sustainable energy sources. Wind energy is considered as one of the efficient source of energy which can be converted to useful form of energy like electrical energy. Though the field of wind engineering has developed in the recent era there is still scope for improvement in the effective utilization of energy. Energy efficiency in wind turbine is largely determined by the aerodynamics of the turbine blades and the characteristics of the turbulent fluid flow. The objective of this paper is to have a review on the improvement of Horizontal Axis Wind Turbine (HAWT) blade design by incorporating biomimetics into blades. Biomimetics is the field of science in which we adapt designs from nature to solve modern problems. The morphology of the wing-like flipper of the humpback whale (Megaptera novaeangliae) has potential for aerodynamic applications. Instead of straight leading edges like that of conventional hydrofoils, the humpback whale flipper has a number of sinusoidal rounded bumps, called tubercles arranged periodically along the leading edge. The presence of tubercles modifies the flow over the blade surface, creating vortices between the tubercles. These vortices interact with the flow over the tubercle and accelerate that flow, helping to maintain a partially attached boundary layer. This aerodynamic effect can delay stall to higher angles of attack, increase lift and reduce drag compared to the post-stall condition of conventional airfoils. The modified airfoil is characterized by a superior lift/drag ratio (L/D ratio) due to greater boundary layer attachment from vortices energizing the boundary layer.
Measure of Utilisation of Government Schemes & Support by Small and Medium Enterprises (SME): Service Providers Perspective
Authors: Gopinath S. , Srivats Balan K. , Ramanathan M. , Narashiman K.
Published: July 2017

The small and medium enterprises (SME) play a vital role in improving the Indian economy. The central and various state governments announce various schemes directly and indirectly for the SMEs.Other SMEs are supported by Government service providers such as Ministry of Micro, Small, and Medium Enterprises (MSME), Small Industries development Corporation (SIDCO), and non-government service providers like Confederation of Indian Industry (CII) etc. Despite several support and facilities, the SMEs are still struggling to run the company. In this regard, authors have decided to study the effectiveness of utilization of various schemes by the SME in the service provider’s perspective. The schemes described in this paper lay emphasis exclusively on the manufacturing sector. Interviews were conducted with officials from different service providers and several flaws were detected in the implementation of these schemes, especially on the schemes reaching the industries. The analysis carried out in the research gives us several findings which elucidate the reason behind the flaws detected. The results of the article will also provide solutions to few critical research questions and provide recommendations which would further enhance the motive behind the schemes being established and reach the industries especially the small and medium-scale ones which would further stabilize the Indian economy.
Process Parameters Optimization of Friction Stir Welding in Aluminium Alloy 6063-T6 by Taguchi Method
Authors: Ganapathy T. , Lenin K. , Pannerselvam K.
Published: July 2017

This paper deals with the effective application of friction stir welding similar to butt joining technique.AL6063 T-6 alloys prepared in 125x 100 x 7mm thickness plate and FSW tool setup were H13 of diameter 25mm rotary tool with straight cylindrical pin profile. The maximum strength was considered for selection of combined process parameter. The process parameters were optimized using Taguchi method. The Rotational speed, welding speed, and axial speed are the main process parameter which taken into our consideration. The optimum process parameters are determined with reference to tensile strength of the joint. From the experiments, it was found the effects of welding parameter are the axial force is highest substantial parameter to determining the tensile strength of the joint. The paper which revealed the optimal values of process parameter are to acquire a maximum tensile strength of friction stir welded AL6063-T6 plates is 101.6Mpa with the combination level of rotational speed, welding speed and axial force are found to be 1100 RPM, 60 mm/min and 12.5 KN. validation test was carried out and results were nearer to the optimized results confirmed by the optimum results.
Ti/B4C Composites Prepared by In Situ Reaction Using Inductive Hot Pressing
Authors: Ariza Galván Enrique , Montealegre-Meléndez Isabel , Arévalo Cristina M. , Kitzmantel Michael , Neubauer Erich
Published: July 2017

In the present work, in situ reinforced titanium composites (TMCs) synthesized using inductive hot pressing (iHP) are studied. The effects of B4C phases and applied processing conditions, on the microstructure and properties of TMCs, are investigated. With the addition of B4C particles, the microstructure of TMCs is refined and the strength is improved.Products of reactions which occur during the manufacturing process are analysed in detail. Microstructure observation illustrates, that B4C survives - depending on the processing conditions. The reinforcing phases are homogeneously distributed in Ti matrix. Moreover, results of densification, mechanical properties and hardness measurements help to identify the most suitable processing conditions to produce this kind of TMCs.
Silver/Diamond Composite Material - Powder Metallurgical Route and Thermo-Physical Properties
Authors: Hutsch Thomas , Schubert Thomas , Weißgärber Thomas , Kieback Bernd
Published: July 2017

To meet the need of high-performance thermal management materials in the field of electronic applications, heat sink materials reinforced with synthetic diamonds have been prepared via powder metallurgy. A matrix of a silver alloy with a silicon content of 0.45 wt.% was chosen out of the prediction of the thickness of a final carbide layer of about 180 nm. The volume content of the diamonds and the diamond size were kept constant. The mixed powders were consolidated by Spark Plasma Sintering (SPS) using different sintering temperatures between 800 and 870 °C with a holding time of 30 min. The maximum thermal conductivity of 680 W/(mK) measured at room temperature and 620 W/(mK) at 275 °C was obtained at 810 °C sintering temperature. The degradation of the most promising sample after one thermal cycle up to 275 °C was determined below 1 percent of the value after sintering.
Mechanical Properties of AlSi12-Based Metal Matrix Composites with Layered Metallic Glass Ribbons
Authors: Lichtenberg Klaudia , Weidenmann Kay André
Published: July 2017

During the last years, several studies proved the high potential of metallic glasses to be used as reinforcements in lightweight alloys. Thereby, focus was mostly on particle reinforced composites or three-dimensional and omnidirectional glass arrays within the composite. Using a specific layered structure of the entire ribbons as reinforcement to design direction-dependent tailored properties is a novel approach. The composites in this study were produced by gas pressure infiltration of a layered stack of metallic glass ribbons. Ribbons of the metallic glass Ni60Nb20Ta20 were used as reinforcements and aluminum alloy AlSi12 as matrix. Mechanical tests like four point bending and tensile tests as well as elastic analysis using ultrasound phase spectroscopy (UPS) were performed to classify composite’s properties. Further, micro computed tomography (µCT) analysis and metallographic investigations were carried out on the four point bending samples after testing to reveal occurring damage mechanisms.
Development of a TiCp Reinforced Ni-Based Superalloy MMC, with High Creep Resistance and Reduced Weight
Authors: Lemos Georges , Fredel Márcio C. , Pyczak Florian , Tetzlaff Ulrich
Published: July 2017

Ni-based superalloys, in both single and polycrystalline varieties, are extensively used in high pressure turbine blades. But contrary to single crystal variants, the polycrystalline forms present easier manufacturing and offer higher potential for improvement in metal matrix composites (MMCs). To benefit from this opportunity, an Inconel X-750 superalloy reinforced with TiC particles is proposed, having a polycrystalline microstructure and the possibility for weight reduction in turbine elements application. The metallic powder with an addition of 15 vol.% of 3.7 μmd TiC particles was prepared through low energy mixing, uniaxial pressing and sintering, followed by a triple heat treatment. The microstructure was analyzed with SEM and XRD techniques. Compressive creep tests were performed at 800 °C with 200 MPa, on both original and reinforced alloys. The study shows how the inclusion of a highly compatible particle reinforcement does not only improves the creep resistance, but also reduces the material weight, thus having potential to promote further reduction in the creep rate on turbine blades submitted to centripetal forces.
Intrinsic Aluminum CFRP Hybrid Composites Produced in High Pressure Die Casting with Polymer Based Decoupling Layer
Authors: Schmid Armin , Arnaut Katharina , Clausen Jan , Koerdt Maximilian , Struss Adrian , Wöstmann Franz Josef , Busse Matthias
Published: July 2017

Combining aluminum and carbon fiber reinforced plastic (CFRP) has been a key focus in realizing lightweight concepts. Manufacturing technologies for high load-bearing and ultra-lightweight CFRP structures have reached a high level of innovation. The same goes for near-net-shape high pressure die casting (HPDC) aluminum components, which can be mass-produced in a highly efficient manner. Yet for hybrid composites of these materials, the solutions to date have relied on conventionally mechanical or adhesive joining techniques. The direct joining of these two materials is problematic, due to their electrochemical intolerance and the resulting corrosive degradation. The joining technology therefore is at the center of this challenge.
The DFG-sponsored joint research project of Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Fiber Institute FIBRE, and Bremen Institute for Mechanical Engineering BIME, all three institutes located at the campus of the university in Bremen, aims at combining aluminum and thermoplastic CFRP into an intrinsic hybrid composite. This is to be achieved in a single-step primary shaping process, avoiding conventional joining techniques like adhesive bonding or riveting. To this end, CFRP structures are to be recast with aluminum, creating an electrochemically decoupling layer between the two materials. This decoupling layer can therefore be considered as a key factor for realizing hybrid composites. It also needs to have a high process reliability and be long-term and mechanically stable. Polyetheretherketone (PEEK) thermoplast was identified as a suitable material for that purpose, given its stability at high temperatures and electrochemical insulation effect.
First test results show the possibility of incorporating CFRP accordingly by HPDC, resulting in a continuous intact decoupling layer of PEEK. The trend indicated that different thermal treatments as well as different aluminum thicknesses of the hybrid casted sample influence the joint strength. On average, in tensile shear tests a joint strength approximately in the range of current single lap adhesive bonds could be achieved.
Process Development for the Ceramic Injection Molding of Oxide Chopped Fiber Reinforced Aluminum Oxide
Authors: Tueluemen Metin , Hanemann Thomas , Hoffmann Michael J. , Oberacker Rainer , Piotter Volker
Published: July 2017

In this study, it was tried to develop a process chain for ceramic injection molding of Al2O3-chopped-fiber reinforced oxide-ceramic-matrix-composite. The feedstocks are compounded at 50 Vol. % filling degree of solid (Al2O3 μ-powder (Taimei Chemicals Co. Ltd.) and 3,2 mm chopped fibers (3M)), in which fiber content varies from 0 Vol. % to 100 Vol. %. As binder system, PE + Paraffin Wax + Stearic Acid are used. The ingredients are compounded in a kneader (Brabender) at 125°C and after the viscosity measurement in the high pressure capillary rheometer at 160°C and certain shear rates, the feedstock is injection molded (Battenfeld) at 160°C, which is followed by debinding process, including chemical (in n-Hexane) and thermal steps, and 2h sintering at different temperatures. Flow paths in the machinery parts, rheological properties of binding system, fiber content and the fiber orientation have significant effect on the flow behavior of the feedstock, fiber -orientation, -distribution & -length, which are crucial to understand the properties of end-parts like mechanical reinforcement of the fibers. The fibers in the sintered parts are ca. 200 μm in average length. The fibers in the feedstock show different orientations depending on the part-geometry and the green bodies have different densities depending on sintering temperature, amount of dispersant and fiber orientation.
Influence of Hardener Content and Curing Parameters on the Microstructure and Mechanical Properties of Porous C/C Composites
Authors: Todt Andreas , Roder Kristina , Nier Natalia , Wielage Bernhard , Wagner Guntram , Nestler Daisy
Published: July 2017

Carbon fibre reinforced carbon composites (C/C) are characterised by their excellent thermal, chemical and mechanical properties. The intrinsic porosity and fibre reinforcement grant them an excellent damage tolerance. The production of complex structures is time consuming and very expensive. An innovative approach to this topic is the integration of simple geometric ceramic composite materials within complex polymer structures. The motivation of this contribution is to investigate the influence of hexamethylenetetramine as hardener (hardener content: 4, 8, 12 and 16 %) and curing parameters (tempered and non-tempered) on the microstructure and mechanical properties of the porous C/C composites. During the course of this contribution, selected carbon fibre reinforced polymer (CFRP) composites with different porosities were produced while adjusting the resin or hardening agent-ratio, as well as the processing parameters. Subsequent to the curing of the CFRP samples, porous C/C composites were produced by means of a pyrolysis process. The final part of the contribution is comprised of the microstructural analysis by light microscopy and the explanation of the flexural strengths, by utilising a “three-point-bending test”.
Material Selection and Process Configuration for Free-Form, Voluminous and Textile-Based Multi-Material-Design by the Example of a Bucket Seat
Authors: Stiller Jonas , Schäfer Kay , Helbig Frank , Tröltzsch Jürgen , Nestler Daisy , Kroll Lothar
Published: July 2017

Hybrid textile-based composites possess an enormous potential for energy and resource efficient large-scale production, with freedom in and high specific mechanical properties. This paper covers the connection of available and established production processes for textiles in a differential process chain for the manufacturing of complex shaped and elastic sandwich components. The technology enables both stiffness and comfort through elasticity.OLU-Preg®-organic sheets, polyurethane foam cores and 3D-spacer fabrics form the targeted properties of demonstrator models. This article refers to the demonstrator part “bucket seat”. To show the benefit of complex composite material, the lightweight and mechanical properties of the sandwich structures are tested in several variations of core and comfort shapes. Absolute and specific improvements of performance are shown in static and dynamic examinations. An Analysis of coupling effects, deformation and failure behavior of the multi-material design (MMD) complete the scientific approach of the structure-property relationships of hybrid composites.