922,169 research outputs found
Experimental analysis of a novel Savonius based spline geometry with flexible blades for Vertical Axis Wind Turbines (VAWT)
No full textCurrently, the wind-power market is dominated by Horizontal Axis Wind Turbines (HAWT) owing to
their high efficiency. Vertical Axis Wind Turbines (VAWT) are far behind in popularity. However, the
interest for future applications of vertical axis wind rotors is increasing because of the simple geometry,
low cost, low sensitivity to turbulent flow conditions and simple and affordable maintenance. Thus, an
improvement in the efficiency of vertical rotors could close the existing gap and make HAWT more
attractive as wind energy conversion devices. In this paper, a new blade spline concept of Savonius
rotor with flexible blades is studied experimentally. The idea is to check the performance improvements
previously achieved by computational CFD simulations. Two Savonius rotors were built using fiber
glass: a rigid rotor with a spline blade shape and a flexible one with the same blade shape but with a
morphing section located at the blade’s tips. Important improvements were registered using the flexible
rotor compared to the same but rigid rotor, in a large working conditions range, validating the CFD
simulation results. The low speed wind tunnel at San Diego State University was utilized for the tests
considering a wind speed in the range of 3.5 to 9.5 m/s. A combined analysis of performance and
flexibility was also performed to find the deformation associated with the best performance for this kind
of rotor. Finally, a comparison was made between the energy conversion of the rigid and flexible rotors
at low wind speed for a possible urban application. Results show a 50% power coefficient improvement
for the flexible rotor compared to the rigid one at the most optimum working condition. A 90% increase
of energy produced by the flexible rotor during one year in the city of San Diego was calculated.
Eventually the most productive wind speed for the flexible rotor was found to be 9m/s. Thus, the
deformation angle obtained at that value (22°- 32°) was considered as the best deformation for this
kind of rotor
Towards the development of scales to measure patent management
No full textThis article aims to propose measurement scales for patent management seen as a macro-process made up of different sub-processes, where activities are carried out, having the firm as our unit of analysis. To this purpose, we followed a recommended six-step methodological approach for new scale development and validation widely recognized in the literature, and specifically this article focused on the first two steps (i.e. specify domain of construct and item generation) for which both a theoretical analysis, through an in-depth literature review, and a qualitative analysis, through interviews, were conducted. The analysis of the literature and the interviews with experts allowed us to develop a measurement framework of patent management by identifying four core processes, namely patent generation, patent portfolio management, patent exploitation and enforcement and patent intelligence, and two supporting dimensions, namely strategy and organization. Beyond that, we categorised activities within each core process and organizational aspects within each supporting dimension with associated measurement items. The findings have both managerial and theoretical implications. For managers, the current article offers a clear conceptualization and measurement scales that can be used as an assessment tool to evaluate firm patent management. Beyond that, future research can benefit from a solid foundation to extend our knowledge of patent management still further by having measurement items at disposal
The patent management process: an exploratory factor analysis
No full textPurpose – Academics and practitioners have been interested in the organizational and managerial aspects of patent management. However, less attention has been devoted to developing a measurement scale of it. Considering this, the current article proposes a holistic measurement framework for firm level patent management and empirically assesses the underlying factor structure.
Design/methodology/approach – The procedure in this article followed three steps: the first two steps include specifying the domain of constructs and generation of measurement items through a review of existing literature and interviews with experts. In the third step, exploratory factor analysis (EFA) was used to purify the scale.
Findings – The study yields that patent management has four core dimensions, namely generation, portfolio management, exploitation & enforcement, and intelligence, and two supporting dimensions, namely strategy and organization of patent management. A framework with patent management constructs and their measurement items was developed for each dimension. Then, using EFA the measurement items were purified, and the underlying factor structures identified.
Practical implications – From a theoretical standpoint, researchers can use the framework to analyze the dynamics of patent management in different industries or they can use the scales to test hypotheses about the relationship between dimensions of patent management and firm performance. In addition, managers can use this framework as a management assessment tool to understand the level of sophistication of their patent management and compare themselves with other firms in the industry to evaluate the technological and competitive position. Moreover, the measurement of the current level of patent management can be used as a basis for managers and entrepreneurs to adopt a proactive attitude towards patent management.
Originality/value – This study represents a first step towards a more holistic theoretical conceptualization of the patent management process and the development of sound scales to measure patent management. It responds to a recent call for more qualitative and quantitative studies on patent management, thus laying the basis for developing a recognized landmark within the research area of patent management
Agricultural transformation in Ethiopia : state policy and smallholder farming
No full textFor thousands of years, Ethiopia has depended on its smallholding farmers to provide the bulk of its food needs. But now, such farmers find themselves under threat from environmental degradation, climate change and declining productivity. As a result, smallholder agriculture has increasingly become subsistence-oriented, with many of these farmers trapped in a cycle of poverty. Smallholders have long been marginalised by mainstream development policies, and only more recently has their crucial importance been recognised for addressing rural poverty through agricultural reform. This collection, written by leading Ethiopian scholars, explores the scope and impact of Ethiopia’s policy reforms over the past two decades on the smallholder sector. Focusing on the Lake Tana basin in northwestern Ethiopia, an area with untapped potential for growth, the contributors argue that any effective policy will need to go beyond agriculture to consider the role of health, nutrition and local food customs, as well as including increased safeguards for smallholder’s land rights. They in turn show that smallholders represent a vitally overlooked component of development strategy, not only in Ethiopia but across the global South.CONTENTS: State Policies and Questions of Agrarian Transformation / Atakilte Beyene -- 1. Agricultural Input Supply and Output Marketing Systems / Fentahun Tesafa -- 2. Agricultural Investment Alternatives and the Smallholder Farming Sector / Kassa Teshager Alemu -- 3. Large/Scale Canal Irrigation Management by Smallholder Farmers / Atakilte Beyene -- 4. Determinants of Climate/resilient Agricultural Practices among Smallholder Farmers / Nigussie Abadi and Girmay Tesfay -- 5. Sociocultural Dimensions of Food: The Case of Teff / Gedef Abawa -- 6. The Impact of Malaria Epidemics on Agricultural Production in Dembia and Fogera, 1950/2000 / Fantahun Ayele -- 7. Women Farmers’ Land Rights in the Context of Constraining Cultural Norms / Mulunesh Abebe Alebachew -- 8. Rural Transformation through Robust Land Rights / Daniel Ambaye -- Concluding Remarks / Atakilte Beyene</p
Agricultural transformation in Ethiopia : state policy and smallholder farming
No full textFor thousands of years, Ethiopia has depended on its smallholding farmers to provide the bulk of its food needs. But now, such farmers find themselves under threat from environmental degradation, climate change and declining productivity. As a result, smallholder agriculture has increasingly become subsistence-oriented, with many of these farmers trapped in a cycle of poverty. Smallholders have long been marginalised by mainstream development policies, and only more recently has their crucial importance been recognised for addressing rural poverty through agricultural reform. This collection, written by leading Ethiopian scholars, explores the scope and impact of Ethiopia’s policy reforms over the past two decades on the smallholder sector. Focusing on the Lake Tana basin in northwestern Ethiopia, an area with untapped potential for growth, the contributors argue that any effective policy will need to go beyond agriculture to consider the role of health, nutrition and local food customs, as well as including increased safeguards for smallholder’s land rights. They in turn show that smallholders represent a vitally overlooked component of development strategy, not only in Ethiopia but across the global South.CONTENTS: State Policies and Questions of Agrarian Transformation / Atakilte Beyene -- 1. Agricultural Input Supply and Output Marketing Systems / Fentahun Tesafa -- 2. Agricultural Investment Alternatives and the Smallholder Farming Sector / Kassa Teshager Alemu -- 3. Large/Scale Canal Irrigation Management by Smallholder Farmers / Atakilte Beyene -- 4. Determinants of Climate/resilient Agricultural Practices among Smallholder Farmers / Nigussie Abadi and Girmay Tesfay -- 5. Sociocultural Dimensions of Food: The Case of Teff / Gedef Abawa -- 6. The Impact of Malaria Epidemics on Agricultural Production in Dembia and Fogera, 1950/2000 / Fantahun Ayele -- 7. Women Farmers’ Land Rights in the Context of Constraining Cultural Norms / Mulunesh Abebe Alebachew -- 8. Rural Transformation through Robust Land Rights / Daniel Ambaye -- Concluding Remarks / Atakilte Beyene</p
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
LIGHT WEIGHT DESIGN AND VEHICLE SAFETY
No full textSUMMARY
Light-weightiness and safety are the two most important requirements that a modern passenger car have to satisfy to stay in the current competitive market. These two targets seem to be in deep contrast one with the other as the high crashworthiness requirements and the consumer expectation for a refined and comfortable cabin, consistently increased both the mass and size of the vehicle over the decades. This trend comes out as quite problematic for the car manufacturers that, at present, are very motivated to pursue the first requirement (the lightweight) that is deeply affecting both fuel consumption and the emission performance of the vehicle.
It is becoming more and more evident that by continuing to use the current conventional metallic materials for front crash structures and other vehicle components, it is more and more difficult to get a design solution capable to satisfy the conflicting interests between the vehicle light-weightiness and safety. Besides, some vehicle weight reduction techniques such as Vehicle design changes and Vehicle downsizing have an adverse effect on both customer comfort and safety, since vehicle size and occupant safety are positively related. As a response , today, researchers and car makers development departments are leaned toward finding high performance, advanced materials such as composite, which have higher Specific Energy Absorption (SEA) performance, in order to break the above mentioned conflicting relationship and truly yield to increase safety and, at the same time, reduce weight.
Composite materials have the following main advantages for transportation industries
• Weight reduction with improved performance ( specific strength 50% less than aluminum and 75% less than steel)
• Crash worthiness/safety i.e. structure built with composite can be 6 to 8 times safer than the similar one made by metal due to higher SEA and more favorable failure mode. As a consequence less intrusion into the passenger compartment during a crash event can be achieved.
• Larger number of options available to the designer. The reinforcement type and its form produce an infinite variety. Thus stiffness and strength properties can be selected in a range that is extended from mechanical properties comparable with thermoplastic materials to properties, which are greater than high performance steels.
However, to implement composite materials for primary and secondary structural applications and substitution of the current traditional material is not straightforward. In fact, although modern composites introduction is dated back 1937, the rate of usage of composites in the automotive industry in all these years has been very slow and the applications have been limited. Some of the reasons are cost i.e. (raw material and manufacturing costs), volume of production (production rate) and insufficient engineering data such as data of material property, sufficient knowledge about failure behaviors, joining, damage inspection and maintenance.
The study presented in this thesis is motivated and drawn from the above stated problems. It is aimed to address at some extent the effect of the material change for vehicle structures and to give research and development contributions to some of the challenges. As lack of engineering data and well established knowledge on composite damaging mechanism are major design constraints on the area, E-Glass/Epoxy composite has been selected and tensile experimental program were designed for material characterization and damage analysis. Both destructive and non destructive damage observation techniques had used to understand the damage extent in the laminate and to capture on-set total failure.
Vehicles are operated under arduous conditions; therefore all components are experiencing some form of fatigue loading during most of their service life. This type of failure is usually considered as the principal mode of failure of all dynamically loaded mechanical systems and accounts approximately 90 percent service failures. Especially, when such fatigue failure occurs on some safety critical components, it will affect the vehicle integrity and could result in a complete loss of control of the vehicle that is highly risky for the life of occupants and vulnerable road users (VRU) such as pedestrians, motorcyclists and cyclists and persons in personal mobilized devices (e.g.: motorized wheelchairs and scooters). Therefore, when new advanced material is proposed for such an application it has to be accompanied by a detailed fatigue analysis.
In this thesis more emphasis had given on the subject and extensive research has been conducted on the fatigue behavior of the selected material. Displacement controlled four point bending fatigue tests with R ratio of 0.1 were conducted on standard and notched specimens and damage development in the composite was continuously monitored through the decrease of bending moment during cycling. The specimens were subjected to different fatigue loading with the maximum loading level up to 75% of the material ultimate flexural strength (UFS). Having obtained an average complete diagram of the fatigue life of the material, in order to understand the type of failure mode and the possible mechanism at different stage of loading, some critical data points have been selected at various stiffness degradation rate and interrupted fatigue tests were conducted to pre-defined number of cycles . Through analyzing the pre cycled specimens using scanning electron microscope (SEM), the failure mode at the three distinctive regions of stiffness degradation regions have been identified. Furthermore, an effort has been made to study effect of notch geometry and notch size on the flexural quasi-static and fatigue performance of the selected material.
Automobile safety in general is the study and practice of design, construction, equipment and regulation to minimize the occurrence and consequences of automobile accidents .It is categorized as active safety (Crash Avoidance) and passive safety (Crashworthiness). In the current work, safety is mainly referred passive safety which is measured by conducting impact physical tests or by numerical simulations at component, sled and full-scale level against a deformable or rigid barrier. The component test is aimed to determine the dynamic and/or quasi-static response to loading of an isolated component and crucial in identifying the crush mode and energy absorption capacity. Understanding their performance is also essential to the development of prototype substructures and mathematical models.
Therefore, to address the issue of volume of production and production cost, as both are main constraints for transportation industries, an effort had made to identify a vehicle component where pultruded composite products can be used,( as pultrusion manufacturing technologies is relatively cheapest (due to process automation) and suitable for high volume production). After material mechanics and failure study, automotive bumper beam were identified as a suitable candidate component for the desired objective and a finite element simulations are performed using ABAQUS, in order to optimize beam section profile and beam curvature of a bumper for crashworthiness.
The research activity is subdivided in two parts and compiled by six chapters. The first part contains four chapters and the second part contains two chapters. As highlighted in the previous paragraph, to understand the material failure behavior is crucial for candidating a novel material for crash absorbing components. The first part of the work is dedicated to material characterization and investigation of the failure mechanism of the selected material and the second part is extended to a component level.
The first chapter covers overall introduction about composite material and its application in automotive industries. The chapters briefly discuss about type of materials that constitute composites and their behaviors, composite manufacturing techniques and the overall requirement of maternal for automotive applications.
The second chapter is dedicated to material characterization and damage study on a selected composite material with and without the presence of notch. In this activity, primarily, an effort has been made to reduce the manufacturing (drilling) induced damage by closely controlling and selecting appropriate manufacturing parameters through conducting damage observations. Having relatively damage free coupon, the material is characterized and a comprehensive damage study is made through conduction of interrupted tensile tests and the material damage extent at different loading level is studied using different damage observation techniques.
The third and fourth chapters cover a four points quasi- static and bending fatigue study of the same material. In chapter three, the bending fatigue behavior of fabric E-Glass/Epoxy composite is investigated. Material stiffness degradation is used as a measure of damage formation and propagation and it is continually monitored using LVDT transducer. Having obtained an average material stiffness degradation trend through conducting test up-to failure for some set of coupons, critical stiffness degradation points are identified. Then an interrupted fatigue test is conducted for a predefined number of cycles to investigate the damage extent at different stage of damage propagation. In chapter four, the effect of notch on the quasi- static and bending fatigue performance of the selected material is discussed. The effect of notch geometry, notch size and loading type are also considered for the study. The used instrumentation and damage monitoring techniques are similar to what presented in chapter three.
In chapter five that is belonging to the second part a numerical study is conducted to explore the possibility of substituting the current metallic bumper beam with E-Glass/epoxy pultruded composites and its energy absorbing capability is compared with steel and E-Glass fabric composite. Since optimal design of composite crash absorber cannot be achieved by a simply material substitution, structural optimization of the beam section profile and curvature is also developed to obtain a stable flexural failure of the composite bumper beam. The analysis is done through the investigation of impact event characteristic data, such as force/time, force/deflection, energy/displacement and deflection/time curves. Finally in chapter six the main findings of the activity are briefly summarized
Experimental evaluation of three different configurations of constructal disc-shaped heat exchangers
No full textThe aim of this work is to experimentally evaluate three different compact branched heat exchangers, measuring, for every single device, the thermal efficiency and the pressure drop. The generality of the analysis of phenomena is enhanced by a comparison of the performance of different refrigerant fluids. In the first configuration, the channels have been designed, varying the inner diameter, to allow for an average constant flow speed throughout the exchanger. In the second one, the flow Reynolds number inside of the channels has been maintained constant. The last configuration is built according to the constructal diameter variation, as indicated in Bejan Constructal Theory. The exchanger manufacturing process is described in detail. The test bench has been assembled using a hot source (Heating Plate with a power of 500 W) and a submersible pump, needed for the fluid recirculation, coupled with flowmeters, to control the mass flow rate within a specific range. The data obtained from several comparative tests have been analyzed, to determine the optimal solution for each refrigerant among the different exchangers
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
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