117,811 research outputs found

    Plasticity effects in subsequent simulations of car structures

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    In order to further reduce the weight of car components while at the same time\ud maintaining performance and safe life it is necessary to enhance the simulation process. This\ud is especially important for chassis parts which have not only a high dynamic load but are also\ud partly undamped. To reach this goal, the logical step is to couple the successive operations of\ud forming, assembly and virtual performance testing.\ud The objective is a complete determination of the mechanical state of the (sub-)assemblies.\ud It is therefore necessary to consider all forming and joining processes a part has previously\ud undergone and to consider them in the virtual model. This virtual model is ideally suited for\ud virtual prototyping (e.g. structural analysis, fatigue, crash) because the complete history of\ud every part is contained. In contrast to standard models, the changed thickness of sheet metal\ud parts and residual stresses due to forming and joining as well as the new material state at\ud every point are known prior to any external loading. This results in a more reliable prediction\ud of product performance.\ud Using a relatively simple part it is demonstrated how the performance of chassis parts\ud changes with the inclusion of plastic forming effects as compared to the exclusion of these\ud effects. The transfer of the results of the forming process to the comprehensive model is shown\ud first. Hereafter the model is subjected to static and dynamic external loads. The results are\ud compared to calculations that use a standard model and show clearly that the inclusion of the\ud plastic history has a significant influence on the product performance

    The potential use of service-oriented infrastructure framework to enable transparent vertical scalability of cloud computing infrastructure

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    Cloud computing technology has become familiar to most Internet users. Subsequently, there has been an increased growth in the use of cloud computing, including Infrastructure as a Service (IaaS). To ensure that IaaS can easily meet the growing demand, IaaS providers usually increase the capacity of their facilities in a vertical IaaS increase capability and the capacity for local IaaS amenities such as increasing the number of servers, storage and network bandwidth. However, at the same time, horizontal scalability is sometimes not enough and requires additional strategies to ensure that the large number of IaaS service requests can be met. Therefore, strategies requiring horizontal scalability are more complex than the vertical scalability strategies because they involve the interaction of more than one facility at different service centers. To reduce the complexity of the implementation of the horizontal scalability of the IaaS infrastructures, the use of a technology service oriented infrastructure is recommended to ensure that the interaction between two or more different service centers can be done more simply and easily even though it is likely to involve a wide range of communication technologies and different cloud computing management. This is because the service oriented infrastructure acts as a middle man that translates and processes interactions and protocols of different cloud computing infrastructures without the modification of the complex to ensure horizontal scalability can be run easily and smoothly. This paper presents the potential of using a service-oriented infrastructure framework to enable transparent vertical scalability of cloud computing infrastructures by adapting three projects in this research: SLA@SOI consortium, Open Cloud Computing Interface (OCCI), and OpenStack

    Epidemiological and awareness study of tuberculosis in Batu Pahat, Johor, Malaysia

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    Tuberculosis (TB) remains one of the serious infectious diseases and has been characterized worldwide as an epidemic by World Health Organization (WHO). TB is still a public health problem in Malaysia. Baseline information on the disease situation is one of the prerequisites for the development of appropriate control measures. The cornerstone in proper management of TB patients is ensuring high awareness in communities about TB. Thus the current research is directed to investigate the epidemiology of TB, determined the level of public awareness of TB and some factors that are responsible for the emergence of TB. Retrospective method was used for collecting epidemiological data from the Batu Pahat chest clinic. All registered TB patients (total of 1213 patients) from 2008 to 2013 in Batu Pahat Chest Clinic were included in the study. On the other hand, the awareness study was carried out by the use of questionnaires. A two-stage cluster sampling method was used. 600 respondents were targeted which form the study sample. However, 498 questionnaires were returned. Descriptive data analysis was employed to describe the results in frequency and percentage distribution. It was discovered that there was an annually increase in TB incidence with pulmonary TB the most common infection in Batu Pahat. Almost all (92.7%) the TB cases were new. On the other hand, majority (87.0%) of respondents have heard about TB. Common symptoms identified by respondents were coughing for over 2 weeks (51.8%), hemoptysis (49.2%) and difficulty in breathing (50.2%). Smoking cigarette (74.3%), living with individual having chronic cough (71.5%) and HIV/AIDS (65.7%) were the common risk factors of TB identified by respondents. Most of the respondents (83.5%) were aware of the existence of TB drugs. However, the standard DOTs treatment duration of 6-9 months was identified by few (12.4%) respondents. This research provided information regarding TB status in Batu Pahat. The level of awareness among Batu Pahat general public about TB is fairly good. Meanwhile, more need to be done especially on diabetes as the risk factors of TB and treatment duration

    Kajian amalan budaya Orang Asli Suku Kaum Jakun di Kampung Peta

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    Orang Asli suku kaum Jakun kaya dengan pelbagai budaya yang unik dan tersendiri. Arus globalisasi kini, telah memberi kesan kepada pengamalan kebudayaan warisan mereka dalam kehidupan seharian. Hal ini disebabkan kurangnya penglibatan daripada generasi muda hari ini. Terdapat tiga objektif dalam kajian ini iaitu mengenalpasti jenis budaya material dan bukan material yang terdapat di Kampung Peta, mengkaji kecenderungan generasi muda kepada pengamalan budaya warisan suku kaum mereka dan menganalisis langkah untuk mengekalkan amalan budaya warisan Orang Asli Jakun di Kampung Peta. Metodologi yang digunakan adalah berbentuk kualitatif dengan menyediakan dua set soalan temu bual mendalam kepada kumpulan fokus atau focus group, pemerhatian peserta dan pemerhatian tidak turut serta. Responden adalah terdiri daripada dua kumpulan iaitu penduduk Jakun di Kampung Peta yang mempunyai kemahiran dalam aspek amalan budaya dan generasi muda iaitu remaja dan belia Jakun untuk mencapai objektif kajian pertama dan kedua. Hasil kajian utama terdapat amalan budaya yang masih dilakukan dan dijalankan di Kampung Peta iaitu amalan budaya material yang terdiri daripada suku kaum Jakun, gelaran, dialek, peralatan, kraf tangan, makanan, nyanyian, tarian dan tempat tinggal. Bagi amalan budaya bukan material ialah agama dan kepercayaan serta perubatan tradisional manakala kecenderungan generasi muda kepada pengamalan budaya warisan kerana mereka tidak menunjukkan minat dan komitmen untuk mewarisi amalan budaya tersebut. Justeru, langkah pengekalan bagi mengekalkan kebudayaan suku kaum mereka iaitu dengan cara pengkomersialan produk budaya, memperkasa dan meningkatkan kebolehan Orang Asli, memberikan pendedahan yang khusus, memberi galakan dan insentif dan mewujudkan Rumah Budaya. Cadangan ini bukan sahaja boleh mengekalkan amalan budaya tetapi sebagai medium kesinambungan warisan untuk pengetahuan dan tatapan generasi akan datang

    Recent Achievements in Numerical Simulation in Sheet Metal Forming Processes

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    Purpose of this paper: During the recent 10-15 years, Computer Aided Process Planning and Die Design evolved as one of the most important engineering tools in sheet metal forming, particularly in the automotive industry. This emerging role is strongly emphasized by the rapid development of Finite Element Modelling, as well. The purpose of this paper is to give a general overview about the recent achievements in this very important field of sheet metal forming and to introduce some special results in this development activity. Design/methodology/approach: Concerning the CAE activities in sheet metal forming, there are two main approaches: one of them may be regarded as knowledge based process planning, whilst the other as simulation based process planning. The author attempts to integrate these two separate developments in knowledge and simulation based approach by linking commercial CAD and FEM systems. Findings: Applying the above approach a more powerful and efficient process planning and die design solution can be achieved radically reducing the time and cost of product development cycle and improving product quality. Research limitations: Due to the different modelling approaches in CAD and FEM systems, the biggest challenge is to enhance the robustness of data exchange capabilities between various systems to provide an even more streamlined information flow. Practical implications: The proposed integrated solutions have great practical importance to improve the global competitiveness of sheet metal forming in the very important segment of industry. Originality/value: The concept described in this paper may have specific value both for process planning and die design engineers

    Laser Shock Microforming of Thin Metal Sheets

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    Continuous and long-pulse lasers have been used for the forming of metal sheets in macroscopic mechanical applications. However, for the manufacturing of micro-electromechanical systems (MEMS), the applicability of such type of lasers is limited by the long-relaxation-time of the thermal fields responsible for the forming phenomena. As a consequence of such slow relaxation, the final sheet deformation state is attained only after a certain time, what makes the generated internal residual stress fields more dependent on ambient conditions and might make difficult the subsequent assembly process from the point of view of residual stresses due to adjustment. The use of ns laser pulses provides a suitable parameter matching for the laser forming of an important range of sheet components used in MEMS that, preserving the short interaction time scale required for the predominantly mechanic (shock) induction of deformation residual stresses, allows for the successful processing of components in a medium range of miniaturization, particularly important according to its frequent use in such systems. In the present paper, a discussion is presented on the physics of laser shock microforming and the influence of the different effects on the net bending angle. The experimental setup used for the experiments, sample fabrication and experimental results of influence of number of laser pulses on the net bending angle are also presented

    Acoustic performance in a lightweight ventilated façade for building refurbishment: analysing the impact of variations in airborne sound insulation according to the ventilation characteristics

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    The use of double-sheet enclosures with an intermediate air chamber in façades guarantees a higher quality of acoustic insulation against external airborne noise. The effective advantages of the intermediate air chamber depend mainly on its airtightness and the absorbent material contained inside. A ventilated façade with lightweight cladding (LVF) is a specific construction system for double-sheet envelope façades, characterised by an intermediate air chamber that enables a certain amount of internal air circulation, with resulting cooling effects to alleviate excess solar radiation whilst reducing the risk of dampness caused by rainwater. However, owing to this ventilation of the intermediate air chamber, the acoustic insulation of the entire façade could prove less effective than cases in which the intermediate air chamber is completely sealed. Through various methods of measurement and analysis, several authors consider that the opening of the intermediate air chamber for hygrothermal control purposes does not necessarily represent a significant reduction in the level of sound insulation in general. What does appear to have a significant influence on the acoustic behaviour is the surface and location of the intermediate air chamber openings to enable ventilation. The results of this research are presented as further evidence that the positive contribution of LVF should be acknowledged at a regulatory level regarding sound insulating, double-sheet envelope architectural façades.Peer ReviewedPostprint (published version

    Crystal structure of the N-benzyloxycarbonyl-Alanyl-Phenylalanyl-methyl ester: the importance of the H-bonding pattern

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    Large crystals of the methyl ester of the N-a-benzyloxycarbonyl protected Ala-Phe dipeptide (Z-AF-OMe) were obtained after the very slow evaporation of a solution of the corresponding carboxylic acid (Z-AF-OH) in methanol containing an excess of HCl. The structure was confirmed by single crystal X-ray diffraction data. It crystallizes in the orthorhombic space group P212121 with unit cell dimensions a = 5.0655(6) Å, b = 8.4614(8) Å, c = 46.856(5) Å, V = 2008.3(4) Å3, Z = 4. In the crystal, the molecules form hydrogen bonded chains running along the a axis of the unit cell. Other secondary interactions are also discussed

    Sliver Solar Cells

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    Sliver solar cells are thin, mono-crystalline silicon solar cells, fabricated using micro-machining techniques combined with standard solar cell fabrication technology. Sliver solar modules can be efficient, low cost, bifacial, transparent, flexible, shadow-tolerant, and lightweight. Sliver modules require only 5 to 10% of the pure silicon and less than 5% of the wafer starts per MWp of factory output when compared with conventional photovoltaic modules. At ANU, we have produced 20% efficient Sliver solar cells using a robust, optimised cell fabrication process described in this paper. We have devised a rapid, reliable and simple method for extracting Sliver cells from a Sliver wafer, and methods for assembling modularised Sliver cell sub-modules. The method for forming these Sliver sub-modules, along with a low-cost method for rapidly forming reliable electrical interconnections, are presented. Using the sub-module approach, we describe low-cost methods for assembling and encapsulating Sliver cells into a range of module designs
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