bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of High-Tech Entrepreneurship on Regional Development
Authors: del Mar Miralles-Quiros Maria , Miralles-Quiros Jose Luis , Daza-Izquierdo Julio
Published: August 2017

In a globalized business environment characterized by the existence of mature sectors, it is essential to focus our attention on those firms with low entry barriers as well as high growth potential in order to design adequate regional development policies. In this context, we analyze firm growth in Brazilian technology-based companies over the 2002-2013 period testing the Law of Proportionate Effect which allows us to provide useful information for policy makers. This study confirms that firm growth is not a random process and, most importantly, we observe that there has been a positive and significant effect of more profitable firms on firm growth in years of global recession. Consequently, we highlight that public policies should be focused on small, profitable and less indebted firms of the technology-based sector because they would contribute to business dynamism and job creation.
The Impact of Academic Stress on Students' Performance
Authors: Iurea Corina , Safta Cristina Georgiana
Published: August 2017

Studies conducted in recent years throughout the world have shown that people are growingly more exposed to stress, its level increasing dramatically over time. Thus, stress has been identified as one of the major scourges of our modern era. It seems that not only adults but also children are affected; pupils and students are also experiencing stressful life situations that can be harmful to their overall condition and health. The transition from pre-academic to academic education, the need to adapt to independent living, to gain insight into new social networks, to comply with high academic requirements constitute potential stressors that may affect the performance of students. Considering all these issues a comprehensive assessment of stress is required, from the perspective of the authors in the field, from analyzing the views of students in the research group and from formulating a personal opinion which can support the effort to reduce stress using coping strategies so that the academic environment to become a pleasant place for students.
Education for a Culturally Hybrid World
Authors: Dobrinescu Anca Mihaela
Published: August 2017

In an international context of increased heterogeneity, education such as that offered by higher education institutions is very unlikely to help manage the cultural clash and prevent violence. If academic curricula exclusively aim at developing professional competences, the students' adaptation to societies characterized by frequent cultural commingling and encounter is almost impossible to happen. In the absence of intercultural competence, the conflict between cultures is imminent. In this chapter, we attempt to show that through teaching literature, contemporary fiction in particular, by using the reading grid provided by intercultural communication, it is possible to offer students the knowledge, skills and attitudes that would make them more competent intercultural communicators, willing to acknowledge difference and value diversity.
User Experiences and Perceptions of Internet Interventions for Depression
Authors: Drozd Filip , Andersen Caroline Emilie , Haga Silje Marie , Slinning Kari , Bjørkli Cato Alexander
Published: August 2017

The purpose of this chapter is to review qualitative research on user experiences with internet interventions for depression and present original results from in-depth interviews from a preventive unguided intervention for postpartum depression. The first part reviews the literature on qualitative studies of client experiences and perceptions of internet interventions for depression. The next part describes original data from a study investigating participants' experiences using semi-structured interviews, following the modified SWOT-format (i.e., strengths, weakness, opportunities, and threats). In total, 10 pregnant and postpartum women aged 28 to 41 were interviewed. Insights from the current review and study are used as a point of departure for discussing future directions in research on internet interventions for depression. This chapter should be valuable for clinicians, researchers, and other health professionals interested in the applicability of internet interventions for their clients, design of future studies, and development of internet interventions.
Treating Sleep Disorders with an ACT-Based Behavior Change Support System
Authors: Langrial Sitwat Usman , Oinas-Kukkonen Harri , Lappalainen Päivi , Lappalainen Raimo
Published: August 2017

Suitable duration and appropriate quality of sleep are essential for mental and cognitive wellbeing. Sleep disorders, whether mild or severe, have proven to have adverse effects on general wellbeing. One's quality of life could be disturbed as a consequence of various mental conditions, sleep disorders being one of them. Researchers have started paying attention to designing, implementing and evaluating eHealth interventions to address sleep disorders. In this chapter, we highlight findings from a field study that was conducted to evaluate effect of software features on a Web-based intervention for sleep disorders. Tyyne is a Web-based eHealth intervention that will be repeatedly mentioned as Behavior Change Support Systsm (BCSS). Tynne offered weekly modules that were drawn from Acceptance and Commitment Therapy (ACT). From an Information system's perspective, the modules were identified and applied as a persuasive software feature that is promoted by the Persuasive Systems Design Model (PSD Model). The duration of the Web-based intervention was 6 weeks. Upon completion of the intervention, about one third (37.2%) of the participants reported that they could better manage their sleep problems. We argue that a relatively low percentage is still highly encouraging, as treatment of sleep-related disorders is a complicated and understudied area. Manifestly, longitudinal studies would help determine the effect of ACT-incorporated Web-based interventions. However, the chapter underscores the effect of persuasive software features incorporated with ACT-based components as a step towards managing sleep disorders.
An Internet-Based Quantum Biofeedback and Neurotechnology Cybertherapy System for the Support of Transpersonal Psychology
Authors: Valverde Raul
Published: August 2017

Transpersonal psychology is the study of human nature and proceeds on the assumption that human beings possess potentials that exceed the limits of their ego and integrate the spiritual experience within a broader understanding of the human psyche and consciousness. Altered states of consciousness have been used as psychotherapy in transpersonal psychology for decades. A Cyberpsychotherapy system is proposed to support transpersonal psychotherapy. The system can be used to induce non-ordinary state of consciousness that can be used by transpersonal psychologists as a healing tool to cure his patients with psychological problems such as psychosis at a distance location with the help of Internet technologies. The Cyberpsychotherapy system uses quantum signal generator for the induction of altered states of consciousness based on the God's helmet of Persinger (1983). The Cyberpsychotherapy has integrated an EEG that serves as a biofeedback device in order to assess if the patient has reached the desired level of consciousness and can be used it to adjust the frequencies of the signal generator in order to improve the psychotherapy experience of the patient if necessary. A sample of 10 patients was used to test the Cybertherapy system based on Neurotechnology and quantum biofeedback, data was collected and analyzed. Although the results show that the patients were not able to reach the desired level of consciousness for the psychotherapy, there is statistical significant evidence that the proposed system can help to raise the level of consciousness; this can help with future designs that will eventually assist to reach the desired level for the psychotherapy.
The Securitization Theory and Migration
Authors: Tanrısever Oktay F. , Türkmen Hasan Selçuk
Published: August 2017

This chapter aims to provide a theoretical juxtaposition of the case of Russian military involvement in Syrian civil war and its connections with Europe's recent migration crisis. Securitization theories of Copenhagen and Paris schools provide useful tools for contextualizing Russia's efforts to justify its military involvement in the Syrian conflict. This chapter also purports to answer the question of how did Russia manage to facilitate its military involvement through securitization and speech acts despite its diminished international reputation due to the Ukrainian crisis.
Municipalities and Refugee Crisis
Authors: Erçetin Şefika Şule , Potas Nihan , Açıkalın Şuay Nilhan , Özdemir Nedim , Doğan Abdullah Mesut
Published: August 2017

Truly, while some countries are still grappling with policy issues to do with acceptance of the refugees in their respective countries, Turkey has become a safe haven to many, a refugee. This has not only featured the ordinary aspects of food, shelter, drinking water, clothing but also services like education, health, social services and transport assistance. Even more crucially, Turkey has offered other aspects bordering on integration, rights and freedoms, representation, mainstreaming and identity which are critical to the asylum seekers. This makes them feel at home especially given that they may end up staying for a long time or even never return to their homes. Such a process requires multi-dimensional legal and administrative regulation but Turkey has always come up with its own localized version of legal settings to accommodate spontaneous issues. This is what has distinguished Turkey from all other countries in the world given its immeasurable, priceless and invaluable handling of asylum seekers.
Is Turkey Well Prepared for the Integration of Immigrants?
Authors: Fındık Leyla Yılmaz
Published: August 2017

Immigration is an important feature of many societies and it has wide ranging effects on the education systems of hosting countries. The rapid growth in the number of immigrants in Turkey, has transformed the education system. The objective of the study it to outline the present position of immigrants and provide an overview of immigration phenomena in Turkey since 2011. The study also aims to review immigrants in Turkish higher education and discuss potential problems immigrant students may have during integration process. The study elaborates policies and measures to improve the integration process for potential candidates of higher education. Immigrants may have various challenges in integration process to education as well as to higher education. The article also tries to emphasize that immigrants does not only bring challenges but possess a wealth of cultural resources and competencies enabling a diverse and global society.
Valuation and Market-Based Pricing of Economic and Ecosystem Services of Water Resources
Authors: Ghosh Nilanjan , Goswami Anandajit
Published: August 2017

This chapter presents a comprehensive review of valuation of water. Though existing literature has a large number of papers on the significant attempts at valuing water, a number of publications only consider certain specific aspects of water pricing, rarely attempting a comprehensive review. Water pricing, whether by government mandate or in practice, has to take into consideration a host of concerns, and hence cannot be confined to bounds of individual disciplines. This chapter presents a survey that attempts to resolve this gap by summarizing accumulated knowledge on valuation of water resources and dealing separately with valuation of water in the economic and the ecosystem sectors. Under each component, a host of studies attempting valuation of water have been reviewed. Finally, the policy implications of water pricing have also been discussed in light of the scarcity value theory.
Adaptive Coevolution
Authors: Juma Dauglas Wafula , Reuben Makomere , Wang Hongtao , Li Fengting
Published: August 2017

Climate change is having a significant impact on water resources globally; more so in developing countries due to lower resilience and weakened coping mechanisms. Water resource and supply management systems need to be adaptive to the uncertainty and unpredictability posed by this challenge. The current water crisis is mainly that of governance within the water sector. On this premise, this chapter seeks to explore the adaptiveness of water management institutions and systems to climate change impacts, with a focus on Kenya's case. Kenya continues to face numerous challenges relating to water supply, which are further exacerbated by climate change. Prior to the development of key legislative and institutional frameworks, through adoption of the Water Act 2002, the water sector grappled with gross mismanagement, manifested via inefficiency in water service provision and resource degradation. Deploying the conceptual model of adaptive (co)-management institutional prescription of polycentric governance, experimentation, public participation, and management of bioregional scale, this chapter stands to contribute novel insights into designing sustainable, adaptive water governance regimes.
Remote Sensing-Based Evapotranspiration Modelling for Agricultural Water Management in the Limpopo Basin
Authors: Alemaw Berhanu F. , Chaoka Thebeyame Ronald , Munyai Brigton
Published: August 2017

The study was motivated by the need to determine the spatial variation of ET and to test the applicability of RS based methods in arid to semi-arid climates with limited ground-based measurements. In this paper we present results of an effort of determining spatial actual evapotranspiration in the Limpopo basin, the Notwane subcatchment in the south-eastern part of Botswana, using remote sensing data from MODIS and Landsat Data sets. The Simplified Surface Energy Balance Index (S-SEBI) was applied to determine actual evapotranspiration using the seven bands of Landsat and MODIS surface reflectance and temperature channels. Three different dates were used to estimate ET from both Landsat and MODIS scenes. The estimated ET values from the two sensors show approximately equally comparable results. An assessment was also conducted to determine the factors influencing evapotranspiration. No strong correlation was identified for ET against the five factors investigated: Net radiation, NDVI, Surface Temperature, emissivity and surface albedo.
Water Scarcity and Household Coping Strategies in Maun, Botswana
Authors: Mmopelwa Gagoitseope , Towongo Moses Festo , Setambule Thato , Mashabila Fridah
Published: August 2017

Water is basic necessity for life, and in many parts of the world its demand exceeds supply due to socio-economic and environmentally related factors. The village of Maun located in north western Botswana, also known as the headquarters of numerous safari and air-charter operations who run tourism related trips into the Okavango Delta, faces persistent water shortage in spite of its location in an area where surface is abundant. Water shortage has had dire impacts on livelihoods of Maun residents and other economic activities. This study investigated the nature of the water scarcity problem in Maun village. The specific objectives of the study were 1) to investigate the causes of water shortage in Maun, 2) to determine the effects of water scarcity on households, and 3) to determine coping strategies for water shortage in Maun. Data was gathered through interviewing households located in a site severely impacted by the problem. Key informant interviews were also held with water supply authorities at the Department of water Affairs in Maun. This study revealed that water scarcity problem in Maun emanates not from environmental constraints, but rather from poor planning by water supply authorities.
An Integrated Application Ground Penetrating Radar and Seismic Refraction for Non-Intrusive Investigation of Geophysical and Geotechnical Targets
Authors: Laletsang Kebabonye , Moffat Lucky
Published: August 2017

This chapter presents a brief synopsis of geophysical exploration methods useful in geotechnical and environmental applications. The treatment is keyed at the baccalaureate level to enable geophysics graduates to apply these methods with minimal supervision. In the seismic method, the background theory is given. Application emphasis is placed on the reversed refraction profile technique which ultimately allows interpretation using the Generalized Reciprocal Method (GRM) first introduced by Palmer in 1986. The latter part of the chapter provides a review of the Ground Penetrating Radar (GPR) method used in high resolution geophysical surveys. This method has recently been used extensively to map defects developed on ageing road and pipeline infrastructure in Botswana. The treatment of theory is restricted again to suit the baccalaureate level of geophysics courses at university and many application examples are given. A discussion on acquisition parameters is included to guide the reader through implementation of the method.
The 2010 to 2013 Revision of the Geology Curriculum at the University of Botswana
Authors: Mapeo Read Brown Mthanganyika , Chaoka Thebeyame Ronald , Maphanyane Joyce Gosata
Published: August 2017

In this chapter, we describe the revision of the geology curriculum at the University of Botswana and show how it has improved the overall curriculum. One of the important outcomes of the revision was to ensure that prerequisite courses were enforced and students took courses in the proper sequence. This was hitherto not possible as students intending to take geology registered in year II which meant that to complete their degree programme in four years they took Level 100 and 200 geology courses concurrently. This system had a deleterious effect in that students found the geology curriculum very heavy and difficult on account of lack of sufficient background preparation. We believe the revision has resulted in a programme that is very competitive in the region and provides adequate preparation to our students to undertake post-graduate training in overseas and regional universities.
Geomorphic Modelling Application for Geospatial Flood Hazards and Flash Flood Thresholds Forecasting
Authors: Alemaw Berhanu F.
Published: August 2017

In this chapter, a geomorphic modelling is presented and as a tool for geospatial flood hazard and flash flood thresholds forecasting in drainage basins. The flash flood thresholds have been estimated in terms of flash flood guidance values for the various tributary watersheds of a drainage basin considered. It has been demonstrated using the Limpopo drainage basin in southern Africa. This transboundary basin was chosen because of its importance to water supply for the growing population and water demands in its four riparian states. The basin is also subject to frequent flood and drought hazards. Even though, well established hydrological and flood frequency models do exist for flood forecasting, the purpose of this manuscript is to produce indicative flash flood guidance from a drainage basin of diverse regional development and intensive catchment land-use land cover dynamics by shading light on the geospatial portrayal of flood producing determinants. This will be important in lieu of the need for designing flood forecasting and flood early warning systems for this basin which is subject to frequent flooding hazards. Recommendations on flood forecasting and mitigation of flood hazards is provided considering the technical, human capital and institutional challenges that exist in this part of Africa.
Linking Scientific Research to Development Agenda
Authors: Kenabatho P. K. , Parida B. P. , Matlhodi B. , Moalafhi D.B.
Published: August 2017

In recent years, the scientific community has been urged to undertake research that can immediately have impact on development issues, including national policies, strategies, and people's livelihoods, among others. While this is a fair call from decision makers, it should also be realized that science by nature is about innovation, discovery and knowledge generation. In this context, there is need for a balance between long term scientific investigations and short term scientific applications. With regard to the former, researchers spend years investigating (or need data of sufficient record length) to provide sound and reliable solutions to a problem at hand while in the latter, it is possible to reach a solution with few selected analyses. In all cases, it is advisable that researchers, where possible should link their studies to topical development issues in their case studies. In this paper, we use a hydrometeorological project in the Notwane catchment, Botswana, to show the importance of linking research to development agenda for mutual benefit of researchers and policy makers. The results indicate that some key development issues are being addressed by the Project and the scope exists to improve the impact of the project.
OS CONCEITOS DE GEODIVERSIDADE, PATRIMÔNIO GEOLÓGICO E GEOCONSERVAÇÃO: ABORDAGENS SOBRE O PAPEL DA GEOGRAFIA NO ESTUDO DA TEMÁTICA
Authors: Meira Suedio Alves , De Morais Jader Onofre
Published: August 2017

A relação indissociável entre a Biodiversidade e a Geodiversidade gera os diferentes tipos de paisagem, porém o homem com dificuldade de realizar uma análise sistêmica do meio, favoreceu, historicamente, os aspectos bióticos diante os abióticos. Em meio à corrente ambientalista que se instaurou a partir da segunda metade do século XX o conceito de Biodiversidade tem se alicerçado na ciência e no senso comum, mas o mesmo não ocorre com os conceitos de Geodiversidade, o que resulta numa consciência ambiental segmentada. Diante disso o presente artigo objetiva discutir os conceitos de Geodiversidade, Patrimônio Geológico e Geoconservação, elencando algumas das principais discussões realizadas no meio acadêmico, tendo especial atenção para a forma com que a ciência geográfica pode colaborar com a temática. A metodologia empregada baseia-se em levantamento de referencial teórico sobre os conceitos abordados e atividades práticas desenvolvidas em âmbito nacional e global. Para o aprofundamento da discussão conceitual foram realizadas entrevistas com profissionais da Geografia que trabalham na área. Percebe-se que a temática constitui um campo novo e promissor em meio às Ciências da Terra com elevada importância para a conservação do meio ambiente. O caráter interdisciplinar dos estudos e trabalhos práticos constitui uma característica própria desse campo de pesquisa, sendo o geógrafo ideal para atuação mediante a sua formação plural e sua capacidade de analisar a paisagem segundo os aspectos físicos e humanos. Diante disso o presente estudo salienta a necessidade de uma maior inserção da temática em cursos de graduação e pós-graduação em Geografia.
USO DE DIFERENTES MÉTODOS PARA O PREENCHIMENTO DE FALHAS EM ESTAÇÕES PLUVIOMÉTRICAS
Authors: Mello Yara Rúbia de , Kohls Werner , Oliveira Therezinha Maria Novais de
Published: August 2017

Estudos que utilizam dados meteorológicos históricos, comumente, encontram a problemática de haver falhas na série histórica. A precipitação pluviométrica é uma variável climática largamente utilizada em diversos trabalhos relacionados à dinâmica socioambiental.  Sendo assim, o objetivo desta pesquisa foi apresentar um estudo do uso de diferentes métodos de preenchimento de falhas pluviométricas, para um melhor aproveitamento dos dados existentes nas séries históricas. Os métodos utilizados foram: ponderação regional, regressão linear simples e múltipla e ponderação regional com base em regressões lineares. Para tanto, utilizou-se dados de quatro estações pluviométricas localizadas na planície e serra, e quatro estações pluviométricas localizadas no planalto, ambas na região de Joinville (SC). Foi realizado o preenchimento de falhas do mês de junho de 1987 a junho de 2006 e do mês de agosto de 1976 a agosto de 1993. Os resultados mostraram que o método de regressão linear múltipla apresentou os valores mais próximos do real, se mostrando o método mais adequado para o preenchimento de falhas na região de estudo; seguido pelo método de ponderação regional, ponderação regional com base em regressões lineares e regressão linear simples. Cabe ressaltar a importância de se conhecer dados pretéritos da distribuição pluviométrica regional e mais de um método para verificação da validade dos resultados.
Electrodeposition of Chitosan Composite Film and its Application for Protein Conjugation
Authors: Chen Ting , Xiang Cui Li , Xu Fen , Sun Li Xian
Published: August 2017

Developing sensitive, reliable and simple methods for detection of protein biomarkers in complex biological matrixes is a major challenge in recent years. In most cases, immunoassays are performed in muti-well-plates in well-equipped labs, which is time consuming and expensive. There is great interest in transitioning immunoanalysis from the lab so the analytical capabilities of immunoanalysis can be employed to diagnose disease at the point-of-care and monitor the environment in the field. In immunoassay applications, antibodies are immobilized onto biointerface to capture specific biomarkers. To improve the sensitivity and reduce the size of immunosensor, immobilizing antibody at high density is essential. Here, we developed an easier method to conjugate the antibodies within the chitosan composite film and remove the non-specific binding with electrical field.
Polyester Gel Electrolyte with Three Dimensional Network for Efficient Quasi-Solid-State Dye-Sensitized Solar Cells
Authors: Shen Cheng Jia , Huang Qi Zhang , Shi Ji Fu , Fang Yue Yun , Xu Gang , Ge Yan Qing
Published: August 2017

In this work, a series of novel polymer gel electrolytes with 3D network as ion channels were extensively investigated. Four type polyesters, which are poly (glutaric acid pentaerythritol ester) (PGAPE), poly (adipic acid pentaerythritol ester) (PAAPE), poly (suberic acid pentaerythritol ester) (PSAPE) and poly (pentanedioic acid pentaerythritol ester) (PPAPE), were successfully developed for quasi-solid-state dye-sensitized solar cells (DSCs) with a maximum PCE of 5.32% under AM 1.5 illumination. Photoelectrochemical measurements of the DSCs were conducted by using electrochemical workstation. The present findings indicate that the 3D network structure of polyesters can facilitate the ionic transport and improve the PCE of the DSCs.
Analysis of Carrier Transport Mechanism for p-Type SnO Thin-Film Transistor
Authors: Qin Jian , Qiang Lei
Published: August 2017

Temperature effect on the I-V characteristics of tin monoxide thin film transistors (SnO TFTs) has been analyzed. The result shows that the drain current of the SnO TFT obeys the Meyer-Neldel rule under low temperature, where current conduction is a thermally activated process. The carrier transport would be dominated by multiple trapping conduction, while, percolation conduction mechanism holds as the temperature increase.
Studies on the Structure and Properties of ZnSb Thin Films Deposited under Various Sputtering Conditions
Authors: Xu Hao Jie , Qin Juan , Gao Peng Fei , Shi Wei Min , Wang Lin Jun
Published: August 2017

In this paper ZnSb thin films were prepared by radio frequency magnetron sputteringfrom a stoichiometric Zn4Sb3 target followed by thermal annealing. The influence of sputteringconditions on microstructure, surface morphology, crystallinity and electrical transport propertieswere investigated. For the range of sputtering power of 50 W to 125 W and working pressure of 0.7Pa, it was found that the content of compound ZnSb phase in the films as well as film crystallinitycould be enhanced greatly by increasing the sputtering power, and this effect may be reinforced bydecreasing the working pressure to 0.2 Pa. At 0.7 Pa, A maximum value of 2.99 μW/cmK2 of powerfactor measured at room temperature was obtained at 100 W. The sample prepared at the samepower and lower pressure of 0.2 Pa has a room temperature power factor of 5.46 μW/cmK2 which isalmost doubled.
Preparation and Properties of Glutaraldehyde Cross-Linked Silk Sericin Films
Authors: Zhan Fang Yu , Wang Kun Yan , Niu Miao Miao
Published: August 2017

Glutaraldehyde cross-linked silk sericin films were successfully prepared. FTIR was applied to characterize the chemical structure of films. Compared to pure silk sericin, cross-linked silk sericin film with 3% glutaraldehyde was found a new peak at 1620 cm-1 and the peak intensity of cross-linked film decreased markedly, which indicating cross-linking reaction has been occurred. Thermal and swelling behavior of cross-linked films was investigated. The cross-linking reaction increased the thermal decomposition temperature. The swelling ratio of glutaraldehyde cross-linked silk sericin films went up with increasing glutaralehyde loading to 3wt%.
Vertical Wall on an Aluminum Alloy Plate Fabricated by Friction Stir Forming
Authors: Ohashi Takahiro , Tabatabaei Hamed Mofidi , Nishihara Tadashi
Published: August 2017

This paper describes utilization of friction-stir forming (FSF) to generate a single wall on an aluminum alloy plate. The proposed process is as follows. The authors placed a material plate on a die having a variable-width groove and conducted friction stirring on its back surface. The material filled the cavity due to high pressure and heat caused by friction stirring. This process can be applied to generate thermal plate-fins and rib structures. The present study investigates the forming conditions and the corresponding results including the height limit of walls to obtain reference data for applications. In the experiment, a 3mm-thick JIS A5083P-O aluminum plate was utilized as the substrate. With a grove of less than 0.2mm-width, the wall was difficult to generate. The maxim height of the 0.2mm-thick wall formed by FSF was 2.8mm, and its aspect ratio was 14, which was difficult to form using conventional forging. Overall, the relationship between groove width of the die cavity and aspect ratio of maximum wall height to wall thickness followed the fractional curvature. This results implies that the deformable material volume generated by friction stirring is a key factor for wall height.
Multi-Objective Optimization in Electrical Discharge Machining of 6061 Al/SiCp Using RSM and NSGA-II
Authors: Singh Balbir , Kumar Sudhir , Kumar Jatinder
Published: August 2017

In this paper, response surface methodology (RSM) and non sorting genetic algorithm (NSGA-II) are used to optimize the multi-responses of electrical discharge machining of Aluminum Alloy 6061/10%SiCp composite. Experiment is performed to evaluates the effects of process parameters namely peak current, pulse on time, pulses off time and gap voltage on the responses material removal rate (MRR) and tool wear rate (TWR). The central composite rotatable design (CCRD) is utilized to design the experiment using RSM. Analysis of Variance (ANOVA) test is performed to validate model and to further establish the mathematical relation between process parameters and responses. Results are analyzed using ANOVA models. NSGA-II is used to optimize two conflicting responses i.e MRR and TWR. Finally results are validated by confirmatory experiment.
Effects of Deformation and Annealing Temperature on the Microstructures and Hardness of Cu-29Zn-0.6Bi Brass
Authors: Basori Imam , Gadhu Ruther , Sofyan Bondan Tiara
Published: August 2017

The use of lead-free brass is growing due to the restriction of the lead content in many components. Bismuth replaces lead in the brass alloys and contributes to the machinability and pressure tightness characteristics. However, Bi is immiscible in copper and fills the inter-dendritic spaces during solidication that yields negative impacts on the mechanical properties. This research studied the effects of addition of 0.6 wt. % Bi on the characteristics of Cu-29Zn alloy during cold rolling and subsequent annealing process. The Cu-29Zn-0.6wt.%Bi alloy was produced by gravity casting in a metal mold with the dimension of 110x110x6 mm3. The as-cast plate was homogenized at 800 °C for 2 hours and then cold rolled with the level of deformation of 20, 40 and 70 % in multiple passes. The samples with 70% deformation was annealed at 350, 400 and 450 °C for 15 minutes. Characterization of materials included Vickers hardness measurement and microstructural observation by using optical microscope and SEM. The results showed that addition of Bi reduced the grain size, formed discrete globules in the interdendritic areas and increased the hardness. The globules as dispersoid bismuth deformed and filled intergranular spaces during rolling and promoted the formation of cross slip mechanism at the 20% deformation. At the 40% deformation, the globules led to more closely spaced twin lamellae and increased the twinning density. The phenomena created an inhomogeneous deformation and promoted the formation of shear band. Annealing process dispersed the Bi globules into tight structures along the grain boundaries.The presence of dispersed bismuth increased the rate of recrystallization during annealing due to the increased in potential site for nucleation. In contrast, the dispersed bismuth acted as the pinning agent that inhibited the grain growth and developed smaller grain size which resulted in higher hardness.
Study on Fractal Characterization Laws of Cutting Force in CNC Turning Aeronautic Aluminium Alloy 7075-T651
Authors: Xing Bao Liang , Wang Jing , Cao Hui Ying , Zhang Shu Zhong , Wei Wei , Zhang Zheng Mei
Published: August 2017

Based on the experiment of turning aluminium alloy (7075-T651), the relations between the fractal dimensions of cutting forces with machining parameters are studied. Cutting speed, feed speed and cutting depth are considered as the process parameters. The cutting force in turning aluminium alloy operation are measured and the fractal dimension are calculated using the algorithm of correlation dimension. From main effect plots the fractal dimensions of three directions of cutting forces are reduced with the increase of cutting speed, increased with the increase of cutting depth and insignificant with the increase of feed speed. The mathematic models of fractal dimension of cutting force are developed using response surface methodology (RSM). The results of the ANOVA show that cutting speed and cutting depth have remarkable influence to fractal dimension Dx, Dy and Dz.
Simulation of Stress Field in High-Frequency Welded Pipe of Composite Aluminum Alloy
Authors: Wang Zhi Wei , Li Xuan , Chen Hong
Published: August 2017

Based on the finite element model of high frequency welded pipe welded of composite aluminum alloy, the stress-time variation curves of welded pipe in different welding parameters were obtained. The analysis shows that the residual tensile stress in the weld zone is largest. At the same time, the weld tensile test and hydrostatic burst test were conducted. When the residual tensile stress in the weld zone is high, the blasting pressure which the weld can withstand is small, and the cracking position is often in the welded seam zone. To a certain extent, the change of the thermal stress in the welding process and the residual stress in the cooling process can be accurately reflected by the finite element analysis method.
Depth and Horizontal Distance of Surface Roughness Improvement on Vertical Surface of 3D-Printed Material Using Ultrasonic Cavitation Machining Process with Abrasive Particles
Authors: Tan Wei Lun , Vohra Moiz Sabbir , Yeo Swee Hock
Published: August 2017

An investigation has been carried out on the effects of abrasive-aided ultrasonic cavitation machining process on improving the surface roughness of 3D-printed material. The test surface will be placed in a vertical orientation aligned with the central axis of the ultrasonic horn rather than horizontally as commonly practiced. Experimental parameters of abrasive concentration and size is used and the effect on surface roughness at both vertical and horizontal distances away from the horn is examined. It is found that larger abrasive concentration has a positive effect on the depth of surface roughness improvement while a limitation is observed for larger abrasive sizes. No trend in surface roughness improvement is found with respect to the horizontal distance from the horn’s central axis.
A Study of the Interaction between Abrasive Waterjet and Target by CFD and FEM Method
Authors: Hou Rong Guo , Huang Chuan Zhen , Zhu Hong Tao , Wang Jun , Yang Huan
Published: August 2017

The interaction between abrasive waterjet and target is studied by computational fluid dynamics (CFD) and finite element method (FEM). The flow field inside and outside abrasive waterjet (AWJ) nozzle is obtained by CFD software. Then the pressure distribution of the fluid on the target is plotted, which is in well agreement with the force distribution of the AWJ impacting on the target and leads to the material deformation. The interaction between the AWJ and target and the fluid-solid coupling is happened. The cloud figure of the target’s deformation and stress are obtained by FEM software. The AWJ parameters such as the flow velocity, off-set and abrasive volume factor have a great effect on the material deformation and the stress distribution. The study results provide a new method to study abrasive water jet machine mechanism and help to optimize process parameters.
Ferrite-Martensite Dual Phase Treatment of AISI 1040 Steel and Mechanical Characterization
Authors: Gurumurthy B.M. , Sharma Sathya Shankar , Kini U. Achutha
Published: August 2017

The present work is focused on the characteristics of dual phase (Ferrite-Martensite) medium carbon steel (AISI1040) austenized at different inter critical temperatures (750,770, and 790°C). AISI1040 is plain carbon steel with moderate strength and hardness. The machinability of the steel depends upon the balanced properties obtained by preferential control of phases (wt. % and type) by altering the room temperature structure. In this view, the dual phase is obtained by varying wt. % of ferrite and martensite structure in the steel and then subjected to bulk mechanical property (tensile, hardness, impact resistance and microstructure) analysis. As bought steel is subjected to normalizing treatment which is taken as datum for analysis. The dual phase structure obtained is then tempered to enhance the balanced properties. It was observed that hardness and tensile strength increases with low temperature tempering (260°C) compared to high temperature tempering (425°C) and impact resistance is excellent in high tempering temperature.
Mechanical Properties and Microstructure of Graphene-Cement Composites
Authors: Jiang Rui Shuang , Wang Bao Min
Published: August 2017

In this work, two type graphene were dispersed in aqueous solution via sonication, and graphene nanoplatelets (GP) and graphene oxide (GO) were characterized by means of ultraviolet visible spectroscopy (UV-vis), X-ray diffraction (XRD) and transmission electron microscopy (TEM). In addition, the effects of different graphene (GP and GO) on mechanical properties and microstructure of cement-based materials were investigated via filed emission scanning electron microscopy (FESEM). The results suggested that the incorporation of GP and GO both improved the flexural and compressive strength of cement, and the GP had a more prominent impact on the strengths of cement, compared with GO. The flexural and compressive strength of cement increased up to 23.5% and 7.5% with 0.05 wt% GP, respectively. FESEM analysis indicated that the microstructure of GP-cement paste was similar to that of control sample without graphene, whereas, a few flower-like crystals were generated in GO-cement paste. This work could provide a new understanding for further researches of graphene-cement composites.
The Evolution Analysis of Mechanical Properties of Marine Submerged Concrete Based on GRA
Authors: Liang Cheng Yao , Qian Chun Xiang , Kang Wen Ce , Chen Huai Cheng
Published: August 2017

Deterioration of concrete in marine environment and the durability of coastal constructions have raised great concern throughout the world. This work mainly focuses on the compressive strength of concrete in marine submerged environment. Data in previous researches has been collected in this work, which can be used in a particular environment and specific types of concrete for different background, while making it difficult to analysis the influencing factors as a whole. In order to find a relative systematical solution to summarize the data, Grey Relational Analysis method is applied to analysis the mass data collected from previous literates at home and aboard. The purpose of this study is to make a sensitivity analysis of factors influencing the concrete compressive strength in submerged marine environment and guide engineering practice. The results turn out that the initial strength plays the most important role in the final strength after long-term immersion. In addition, the immersing age and cationic ions also affect the final strength of marine concrete. In all, general deterioration exhibits the tendency that upgrading at the very beginning and then descending later.
Three-Dimensional Scanning Hall Probe Microscopy for Final Stage of Crack Growth of Chromium Molybdenum Steel SCM440
Authors: Nakashima Tatsurou , Kida Katsuyuki
Published: August 2017

Crack propagation around the stress concentration area causes fatigue failure. Non-destructive method is necessary for monitoring structure fatigue before destruction. We focused on a magnetic non-destructive evaluation method for crack growth. In order to understand the relation between crack propagation and changes in magnetic flux density, we observed the position of the positive and negative magnetic flux density distributions around the crack of tool steel (SCM440) plate using a scanning Hall probe microscope (SHPM). We found that the vertical component of the three-dimensional magnetic flux density moved as the crack growth. Furthermore, the magnetic component which is parallel to the tensile stress appeared just before destruction of the specimen.
Preparation and Characterization of Pr2Ti2O7 by Sol-Gel Process
Authors: Long Chun Yu , Peng Fang Fang , Jin Min Min , Tang Pei Song , Chen Hai Feng
Published: August 2017

Using Pr (NO3)3, butyl titanate, ethylene glycol and citric acid as main raw materials, praseodymium titanate (Pr2Ti2O7) was prepared by the sol-gel process. The samples were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), thermal gravity-differential thermal analysis (TG-DTA), diffuse-reflection spectra (DRS) and Fourier transform infrared (FT-IR). The effect of different calcination temperature and illumination time on the photocatalytic properties of Pr2Ti2O7 was investigated. It was found that the single phase Pr2Ti2O7 could be obtained through sol-gel process and calcination at 1000 °C. The Pr2Ti2O7 samples calcination at 1000 °C were uniform , and the resulting product had a particle size of 200 nm and an optical band gap of 3.26 eV. Under ultraviolet light, the degradation of methyl orange arrived to 80.11% after 180 min of photocatalytic reaction. The Pr2Ti2O7 samples showed good photocatalytic activity for decomposition of methyl orange.
Tunable Fabrication of Electrospun Polyvinyl Alcohol Nanofibrous Membrances for Effective Air Filtration
Authors: Zhao Jin Yu , Liu Zhao Lin , Shan Ju Chuan
Published: August 2017

Polyvinyl alcohol (PVA) nanofibrous membrances for effective air filtration were fabricated by electrospinning. Tunable fiber morphologies can be formed by facilely regulating the solution concentration and the applied voltage, and their effect on filtration performance of the PVA membrances were also investigeted. Results show that the PVA membrance exhibits high filtration efficiency of 97.1% and low pressure drop of 113 Pa when the PVA concentration is 8 wt% and the applied voltage is 15 kV with a tip-to-collector distance of 15 cm and a feed rate of 1 ml/h.
Preparation and Characterization of YMnO3 by Microwave Assisted Process
Authors: Peng Fang Fang , Jin Min Min , Long Chun Yu , Tang Pei Song , Chen Hai Feng
Published: August 2017

Using yttrium nitrate (Y(NO3)3·6H2O), manganese acetate (MnC4H6O4·4H2O), citric acid (C6H8O7·H2O) and urea (CH4N2O) as major raw materials, the YMnO3 was prepared by microwave assisted method. The structure and morphology of samples were characterized by thermogravimetric analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FT-IR). The results show that the YMnO3 was successfully prepared by microwave process and calcined from 750°C to 1050°C. When the calcination temperature is 850°C, the grain of YMnO3 has good uniformity and the average grain size of 80-100 nm. Under UV-light irradiation, the photocatalytic activity of YMnO3 was studied for methyl orange (MO) used as simulated sewage. The photocatalytic experiment show that the YMnO3 exhibited excellent photocatalytic activity for degradation methyl orange.
Preparation of Cobalt Phthalocyanine Supported Mg-Al Hydrotalcite and its Catalytic Activity for Degradation of Methylene Blue
Authors: Qian Meng Xia , Ma Jian Li , Xu Min Hong
Published: August 2017

A novel supported catalyst is prepared through immobilization of water soluble phthalocyanine, which is synthesized by modifying tetraminophthalocyanine with cyanuric chloride, onto the supporting material Mg-Al hydrotalcite via co-precipitation method. The structure of the catalyst is characterized by infrared spectroscopy instrument (FT-IR) and X-ray diffractometer. Catalytic activity is examined through comparative experiments. The results show that it exhibits high catalytic activity for degradation of methylene blue (MB) in the presence of H2O2, the remaining rate of MB is 12.02% after 6 h. The reaction process conforms to the equation of pseudo-first-order kinetics, and the correlation coefficient R2> 0.99. The recycling tests for five times are also carried out and prove its reusability in catalytic application.
Flame Retardant Effect of a Modified Intumescent Flame Retardant on a Rigid Polyurethane Foam
Authors: Dai Pei Bang , Yang Lin Ying , Zheng Ting , Qin Chang , Tang Qi Chen
Published: August 2017

A rigid polyurethane (PU) flame retardant composite foam was prepared by the compounding of polyols and diisocyanates with a modified intumescent flame retardant (MIFR). The MIFR was based on the three components of intumescent flame retardant normally used and was modified in a surfactant TX-10 solution. The flame retardancy of the PU flame retardant composite foams were evaluated by using the limiting oxygen index (LOI), the UL-94 (vertical flame) test and scanning electron microscopy (SEM). When MIFR was fixed at 20.0 wt% in PU/MIFR composite foams, the MIFR could enhance the flame retardancy and pass V-0 rating of UL-94 test. The microstructures observed by SEM demonstrate that a suitable amount of MIFR can promote formation of compact intumescent charred layers in PU foams.