• Damage in single lap joints of woven fabric reinforced polymeric composites subjected to transverse impact loading

      Choudhry, Rizwan Saeed; Hassan, Syed F.; Li, Shuguang; Day, Richard; National University of Sciences and Technology; University of Manchester; University of Nottingham; Glyndŵr University (Elsevier, 2015-02-16)
      Single lap joints of woven glass fabric reinforced phenolic composites, having four different overlap widths, were impacted transversely using a hemispherical impactor with different velocities in the low velocity impact range. The resulting damage was observed at various length scales (from micro to macro) using transmission photography, ultrasonic c-scan and x-ray micro tomography (XMT), in support of each other. These experimental observations were used for classification of damage in terms of damage scale, location (i.e. ply, interfaces between plies or bond failure between the two adherends) and mechanisms, with changing overlap width and impact velocity. In addition, finite element analysis was used to simulate delamination and disbond failure. These simulations were used to further explain the observed dependence of damage on overlap width and impact velocity. The results from these experiments and simulations lead to the proposal of a concept of lower and upper characteristic overlap width. These bounds relate the dominant damage pattern (i.e. scale, location and mechanism) with overlap width of the joint for a given impact velocity range.
    • Damped forced vibration analysis of single-walled carbon nanotubes resting on viscoelastic foundation in thermal environment using nonlocal strain gradient theory

      Malikan, Mohammad; Nguyen, Van Bac; Tornabene, Francesco; Islamic Azad University; University of Derby; University of Bologna (Elsevier, 2018-08-01)
      In this paper, the damped forced vibration of single-walled carbon nanotubes (SWCNTs) is analyzed using a new shear deformation beam theory. The SWCNTs are modeled as a flexible beam on the viscoelastic foundation embedded in the thermal environment and subjected to a transverse dynamic load. The equilibrium equations are formulated by the new shear deformation beam theory which is accompanied with higher-order nonlocal strain gradient theory where the influences of both stress nonlocality and strain gradient size-dependent effects are taken into account. In this new shear deformation beam theory, there is no need to use any shear correction factor and also the number of unknown variables is the only one that is similar to the Euler-Bernoulli beam hypothesis. The governing equations are solved by utilizing an analytical approach by which the maximum dynamic deflection has been obtained with simple boundary conditions. To validate the results of the new proposed beam theory, the results in terms of natural frequencies are compared with the results from an available well-known reference. The effects of nonlocal parameter, half-wave length, damper, temperature and material variations on the dynamic vibration of the nanotubes, are discussed in detail.
    • Design codes and design language

      Tracada, Eleni; University of Derby; Leeds College of Art & Design (Jeremy Mills Publishing Ltd, 2008)
    • Design of a mini combined harvester.

      Abdulkarim, K. O.; Abdulrahman, Olajide; Ahmed, Ismaila I.; Abdulkareem, Suleiman; Adebisi, Jeleel Adekunie; Harmanto, Dani; University of Johanesburg; University of Ilorin; University of Derby (University of Novi Sad, 2017-06)
      In this research, various problems associated with harvesting of agricultural food grains by local farmers in Nigeria were identified. The aim of the research was to design low cost multipurpose mini combined harvester for production using locally available materials at affordable cost. The research was to ensure improved performance and low cost maintenance of harvester for use by farmers in developing nations. The modelling of the chassis and other components of the combined harvester was done using Solid works 2014. The selection of materials for the design was achieved using Cambridge Engineering Selector (CES) 2014. Calculations for the design of each components and power requirements to determine the engine specifications were carried out to ensure optimal performance. The output of the research was the development of mini combine harvester which is a microcosm of large capital intensive harvester, at affordable cost to small scale farmer in developing nations. The research ensures the use of mechanised farming equipments designed and developed from local materials for effective harvesting and transportation of agricultural produce.
    • Design of new cold rolled purlins by experimental testing and Direct Strength Method

      Nguyen, Van Bac; Pham, Cao Hung; Cartwright, Brian; English, Martin; University of Derby; University of Sydney; Hadley Industries plc (Elsevier, 2017-09)
      New cold roll formed channel and zed sections for purlins, namely UltraBEAM™2 and UltraZED™2, have been developed by Hadley Industries plc using a combined approach of experimental testing, finite element modelling and optimisation techniques. The new sections have improved strength to weight ratio by increasing the section's strength through the use of stiffeners in the section webs. The European standard, Eurocode 3 [1], uses the traditional Effective Width Method to determine the strength of a cold formed steel member. However, the design of the new sections UltraBEAM™2 and UltraZED™2 using this method is very complicated in calculating the effective section properties as these sections contain complex folded-in stiffeners. In addition, the incorporation of competing buckling modes such as distortional buckling of these sections can be difficult to analyse. To overcome difficulties of using Eurocode 3 or such a standard with the Effective Width Method for determining the strength of these sections, the Direct Strength Method is adopted in this paper. Four-point beam bending tests were carried out to determine the buckling and ultimate bending capacities of the UltraBEAM™2 and UltraZED™2 sections. Results from both experimental testing and Finite Element analysis were initially used as validation for the design using the Direct Strength Method. The Direct Strength Method's results were then compared with the experimental test results for a broader data in which the UltraBEAM™2 and UltraZED™2 sections had a range of different width-to-thickness ratios. It showed an excellent agreement between test and Direct Strength design values suggesting that the Direct Strength Method is a powerful tool for the design and optimisation of the new cold roll formed channel and zed purlins.
    • Development of a 3D finite element acoustic model to predict the sound reduction index of stud based double-leaf walls

      Nguyen, Van Bac; Arjunan, Arun; Wang, Chang; Mynors, Diane; Morgan, Tertia; English, Martin; University of Wolverhampton; Hadley Industries plc; University of Sussex (Elsevier, 2014-11)
      Building standards incorporating quantitative acoustical criteria to ensure adequate sound insulation are now being implemented. Engineers are making great efforts to design acoustically efficient double-wall structures. Accordingly, efficient simulation models to predict the acoustic insulation of double-leaf wall structures are needed. This paper presents the development of a numerical tool that can predict the frequency dependent sound reduction index R of stud based double-leaf walls at one-third-octave band frequency range. A fully vibro-acoustic 3D model consisting of two rooms partitioned using a double-leaf wall, considering the structure and acoustic fluid coupling incorporating the existing fluid and structural solvers are presented. The validity of the finite element (FE) model is assessed by comparison with experimental test results carried out in a certified laboratory. Accurate representation of the structural damping matrix to effectively predict the R values are studied. The possibilities of minimising the simulation time using a frequency dependent mesh model was also investigated. The FEA model presented in this work is capable of predicting the weighted sound reduction index Rw along with A-weighted pink noise C and A-weighted urban noise Ctr within an error of 1 dB. The model developed can also be used to analyse the acoustically induced frequency dependent geometrical behaviour of the double-leaf wall components to optimise them for best acoustic performance. The FE modelling procedure reported in this paper can be extended to other building components undergoing fluid–structure interaction (FSI) to evaluate their acoustic insulation.
    • Development of a STEP-compliant design and manufacturing framework for discrete sheet metal bend parts

      Faraz, Zahid; Waheed ul Haq, Syed; Ali, Liaqat; Mahmood, Khalid; Tarar, Wasim Akram; Baqai, Aamer Ahmed; Khan, Mushtaq; Jaffery, Syed Husain Imran; Choudhry, Rizwan Saeed; National University of Sciences and Technology; Capital University of Science and Technology; Department of Mechanical Engineering, College of Electrical and Mechanical Engineering, National University of Sciences & Technology (NUST), Islamabad, Pakistan; Department of Mechanical Engineering, College of Electrical and Mechanical Engineering, National University of Sciences & Technology (NUST), Islamabad, Pakistan; Department of Design and Manufacturing Engineering, School of Mechanical & Manufacturing Engineering (SMME), National University of Sciences & Technology (NUST), Islamabad, Pakistan; Department of Mechanical Engineering, College of Electrical and Mechanical Engineering, National University of Sciences & Technology (NUST), Islamabad, Pakistan; Department of Mechanical Engineering, College of Electrical and Mechanical Engineering, National University of Sciences & Technology (NUST), Islamabad, Pakistan; Department of Mechanical Engineering, College of Electrical and Mechanical Engineering, National University of Sciences & Technology (NUST), Islamabad, Pakistan; Department of Design and Manufacturing Engineering, School of Mechanical & Manufacturing Engineering (SMME), National University of Sciences & Technology (NUST), Islamabad, Pakistan; Department of Design and Manufacturing Engineering, School of Mechanical & Manufacturing Engineering (SMME), National University of Sciences & Technology (NUST), Islamabad, Pakistan; Department of Mechanical Engineering, Capital University of Science & Technology, Islamabad, Pakistan (Sage, 2016-08-09)
      Metal sheets have the ability to be formed into nonstandard sizes and sections. Displacement-controlled computer numerical control press brakes are used for three-dimensional sheet metal forming. Although the subject of vendor neutral computer-aided technologies (computer-aided design, computer-aided process planning and computer-aided manufacturing) is widely researched for machined parts, research in the field of sheet metal parts is very sparse. Blank development from three-dimensional computer-aided design model depends on the bending tools geometry and metal sheet properties. Furthermore, generation and propagation of bending errors depend on individual bend sequences. Bend sequence planning is carried out to minimize bending errors, keeping in view the available tooling geometry and the sheet material properties’ variation. Research reported in this article attempts to develop a STEP-compliant, vendor neutral design and manufacturing framework for discrete sheet metal bend parts to provide a capability of bidirectional communication between design and manufacturing cycles. Proposed framework will facilitate the use of design information downstream at the manufacturing stage in the form of bending workplan, bending workingsteps and a feedback mechanism to the upstage product designer. In order to realize this vendor neutral framework, STEP (ISO 10303), AP203, AP207, and AP219 along with STEP-NC (ISO14649) have been used to provide a basis of vendor neutral data modeling.
    • Development of students’ commercial awareness within the curriculum of professionally accredited courses : A case study of property courses

      Poon, Joanna; Brownlow, Michael; University of Salford (Emerald Insight, 2015)
      Purpose: The purpose of this paper is to discuss the development of students’ commercial awareness within the curriculum of professional accredited courses. The targeted area of study is the Royal Institution of Chartered Surveyors (RICS) accredited property courses. This paper also discusses how the curriculum of RICS-accredited courses can be designed to successfully incorporate commercial awareness within them and suitable delivery methods for developing this within the curriculum. Commercial awareness is one of the most important employability skills, however, employers have expressed dissatisfaction with graduates’ performance in this area. Design/methodology/approach: This paper presents the research findings of two sets of questionnaire surveys, as well as interviews and e-mail discussions with the course directors and current students of the RICS-accredited property courses in the UK. Descriptive analysis was used to analyse the questionnaire data. Fisher’s exact test was used to identify the statistical significance between academics’ and students’ views on the development of students’ commercial awareness as part of the RICS-accredited property courses’ curriculum. Content analysis was used to analyse the texts in the questionnaire survey, interviews and e-mail discussions. Findings: Academics and students involved with the UK RICS-accredited property courses agreed that commercial awareness is an important employability skill in the property sector and they mostly agreed on the definitions of commercial awareness, except in their “understanding of the wider business environment”. They also agreed that commercial awareness has three components: strategic, financial and process. Academics and students agreed that the commercial awareness components and process sub-components are largely incorporated into the curriculum of RICS-accredited property courses but they have divergent opinions on the level of incorporation of strategic and financial sub-components. A suitable way to deliver commercial awareness in RICS-accredited property courses is to incorporate it into the overall curriculum, ensuring that the components of commercial awareness are closely linked to the RICS APC and match relevant competency levels. They also commented that including practical experience in the curriculum is the most useful way to develop a student’s commercial awareness. Originality/value: This paper is the first to discuss the development of commercial awareness in professional accredited courses such as RICS-accredited property courses and also identifies suitable methods to enhance students’ commercial awareness as part of the curriculum. The research findings can also be applied to other professional accredited courses that have a strong vocational focus, such as nursing, engineering and accountancy. These courses are usually accredited by relevant professional organisations and students studying these courses usually plan to embark on a career in a relevant profession. The design of the course curriculum has a strong focus on equipping students with the essential competencies to develop their careers within the relevant field.
    • Diatreta Cups, Light in Roman Dining Spaces

      Carnevale, Valeria; Derby University (DAKAM - Eastern Mediterranean Academic Research Center, 2015-11-03)
      Cage cups or Diatreta are ancient Roman glass vessels produced by creating a thick blown blank of glass that, once cooled down, is taken to a glass cutter or diatretarii. The latter would cut and carve away most of the glass leaving a transparent vessel inside and an open-work decoration separated through thin posts of glass. The work is very delicate and exclusive, produced within limited space in time with no record of similar vessels until the late 1800 (Donald B. Harden & Toynbee 1959, p.181). Many of these glass objects have good-will inscriptions or decorations that express the importance of drinking. As for their provenance, most –when found in context- have been found in pagan burials. Nevertheless some fragments have been found in Christian environments or with Christian motifs like the Szekszárd cup. The location of these finds is mostly in the Rhine area –northern Empire, when Milan was one of its capitals (Aquaro 2004)- but the actual extent of finds expand throughout the 4th century extent of the Roman Empire. Considering their typological analysis there are basically two types, beaker and bowl. Beakers are considered drinking vessels as they either display a legend or a mythological reference to drink or wine. Whereas a general consensus agrees that open bowl-form cups were hanging lamps (Whitehouse 1988, p.28) since the 1986 find of a diatreta bowl with copper alloy hanging attachments. It is clear these were luxury objects to be used in special occasions and spaces. The aim of this paper is to understand the space were socialisation and drinking took place and the importance of luxurious objects to adorn, display and use. The paper will also put forward the idea that the beaker shaped diatreta vessels, usually considered for drinking, could have been lamps that encouraged drinking and good will to the guests. This paper is structured to first consider an introduction to late luxury Roman glass and then analysing the typological shape of all, or most of the diatreta currently known; secondly, through assessment by the means of comparison, analyse the writings or decorations the vessels were endowed with. Thirdly, by describing and understanding the people and the space were these vessels would have been used, emphasise the beauty of illuminating such spaces with these vessels. According to Herodotus in his historical investigation –5th century-, dress habits and food regime are elements of extreme importance to understand a people (Caporusso et al. 2011, p.12). This idea is not only valid for Herodotus’ time but it is something anthropology uses time and again to explain different aspects in people’s way of life. Through food and its environment, the dining space, this paper will aim to put the cage cups into a social context in order to give emphasis to the hypothesis of light versus wine.
    • Dimpling process in cold roll metal forming by finite element modelling and experimental validation

      Nguyen, Van Bac; Wang, Chang; Mynors, Diane; English, Martin; Castellucci, Michael; Hadley Industries plc; University of Wolverhampton; University of Sussex (Elsevier, 2014-08)
      The dimpling process is a novel cold-roll forming process that involves dimpling of a rolled flat strip prior to the roll forming operation. This is a process undertaken to enhance the material properties and subsequent products’ structural performance while maintaining a minimum strip thickness. In order to understand the complex and interrelated nonlinear changes in contact, geometry and material properties that occur in the process, it is necessary to accurately simulate the process and validate through physical tests. In this paper, 3D non-linear finite element analysis was employed to simulate the dimpling process and mechanical testing of the subsequent dimpled sheets, in which the dimple geometry and material properties data were directly transferred from the dimpling process. Physical measurements, tensile and bending tests on dimpled sheet steel were conducted to evaluate the simulation results. Simulation of the dimpling process identified the amount of non-uniform plastic strain introduced and the manner in which this was distributed through the sheet. The plastic strain resulted in strain hardening which could correlate to the increase in the strength of the dimpled steel when compared to plain steel originating from the same coil material. A parametric study revealed that the amount of plastic strain depends upon on the process parameters such as friction and overlapping gap between the two forming rolls. The results derived from simulations of the tensile and bending tests were in good agreement with the experimental ones. The validation indicates that the finite element analysis was able to successfully simulate the dimpling process and mechanical properties of the subsequent dimpled steel products.
    • Do real estate courses sufficiently develop their graduates’ employability skills? Perspectives from multiple stakeholders

      Poon, Joanna; University of Salford (Emerald Group Publishing, 2014)
      Purpose: The purpose of this paper is to investigate whether Royal Institution of Chartered Surveyors (RICS) accredited real estate courses in the UK have equipped real estate graduates with sufficient relevant employability skills to embark on a career in the profession. This paper considers the perspectives of four stakeholders – employers, human resource managers, graduates and course directors of RICS-accredited real estate courses – in the UK. Design/methodology/approach: The results of a mixed-methods study, involving two online surveys with real estate employers and recent graduates of RICS-accredited real estate courses, and two sets of interviews with human resource managers of real estate surveying firms and course directors of RICS-accredited real estate courses, are presented. Findings: The employers and graduates of the RICS-accredited real estate courses do not think the courses sufficiently equip graduates’ with employability skills. On the other hand, the human resource managers are very impressed with graduates’ technical skills but have concerns about their soft skills and attributes. Human resource managers and course directors of RICS real estate courses commented that commercial awareness is an important employability skill but graduates are not well developed in this area. Course directors also noted that practical experience is vital to employability, commenting that students can only obtain real-life practical experience if employers offer them opportunities. Originality/value: This paper makes an original contribution to the existing literature on employability skills for real estate graduates. It describes pioneering research considering the perspectives of four types of stakeholders and evaluates whether real estate courses sufficiently develop graduates’ employability skills.
    • Does subject choice in a joint jonours degree affect highly skilled graduate employment?

      Pigden, Louise; Moore, Garford; University of Derby (Global Research and Development Services, 2017-09-04)
      Joint or combined honours degrees generally permit students to study two subjects to full honours degree depth, by studying half the curriculum content of the respective equivalent single honours degrees. This affords students the opportunity to study a more diverse curriculum that they feel passionate about. However this is at the expense of breadth of study in each particular subject, which is a strong defining feature of the majority of UK single honours degrees. Does the decision to study certain subjects in a joint or combined honours degree affect the graduate’s subsequent highly skilled graduate employment? The literature is weak in examining this, either for joint honours subjects generally or for specific combinations of subjects. This paper presents an analysis of the UK Destination of Leavers from Higher Education survey between 2011/12 and 2014/15 at the level of the individual combinations studied – a national dataset which has not previously been critiqued in this particular way in the public domain. This analysis will determine whether certain combinations lend themselves to higher rates of highly skilled graduate employment, irrespective of other factors affecting employment, for example the characteristics of different universities. We conclude with recommendations around the preparedness or otherwise of graduates for highly skilled graduate employment, as determined by their choice of subjects to study.
    • Editorial: methodologies of sustainable projects

      BK, Satish; Shahzad, Sally; University of Edinburgh (University of Edinburgh, 2013)
      The Edinburgh Architecture Research has been gathering together the postgraduate community in Architecture at the University of Edinburgh for many years. Since 1973 it has been challenging the research students to raise questions and work together to develop calls for papers, and organise the publication of the journal issues. It began as a reviewed collection of papers produced by students and academics of the University of Edinburgh, and it soon developed into a blind, doublereviewed journal of wide recognition, inviting papers from the broader international academic community. In this issue, we have departed from the general process of conference driven proceedings. This time we have paved the way for a theme-based edition with a wider participation from among the academics, students and practitioners. This 33rd edition of EAR is aimed at research papers and design projects that explore sustainable methodologies. Sustainable design requires skilful integration of multiple and often competing social, financial and environmental concerns. It can be argued that designers satisfy the increasingly sophisticated demands and multiple readings of sustainability without sacrificing design legibility. The intention is to explore these topics in the hope that this edition will act as a catalogue for the innovative methodologies deployed through research and design.
    • Educational advantage and employability of UK university graduates

      Pigden, Louise; Moore, Garford; University of Derby (Emerald, 2019-02-20)
      In the UK, the majority of university students specialise and study just one subject at bachelor degree level, commonly known in the UK as a single honours degree. However, nearly all British universities will permit students if they wish to study two or even three subjects, so-called joint or combined honours degrees, internationally known as a double major. The purpose of this paper is to explore whether educational advantage, measured by the “Participation of Local Areas” (POLAR) classification, correlated with rates of graduate destinations for joint and single honours graduates. This study focused particularly on Russell Group and Post-92 Universities. The authors analysed the complete data set provided from the Higher Education Statistics Agency Destination of Leavers from the Higher Education survey, and combined this with data from the POLAR4 quintiles, which aggregate geographical regions across the UK based on the proportion of its young people that participate in higher education. The data were analysed to establish whether there was a difference in the highly skilled graduate employability of the joint honours students, focusing particularly on Russell Group and Post-92 Universities, in order to build on previous published work. Single honours and joint honours graduates from higher participation POLAR4 quintiles were more likely to be in a highly skilled destination. However at both the Russell Group and the Post-92 universities, respectively, there was no trend towards a smaller highly skilled destinations gap between the honours types for the higher quintiles. For the highest POLAR4 quintile, the proportion of joint honours graduates was substantially higher at the Russell Group than at Post-92 universities. Furthermore, in any quintile, there were proportionately more joint honours graduates from the Russell Group, compared with single honours graduates, and increasingly so the higher the quintile. This study focused on joint honours degrees in the UK where the two or three principal subjects fall into different Joint Academic Coding System (JACS) subject areas, i.e. the two or three subjects are necessarily diverse rather than academically cognate. This excluded the class of joint honours degrees where the principal subjects lie within the same JACS subject area, i.e. they may be closer academically, although still taught by different academic teams. However, the overall proportion of joint honours graduates identified using the classification was in line with the UCAS (2017) data on national rates of combined studies acceptances. All Russell Group graduates, irrespective of their POLAR4 quintile, were far more likely to be in a highly skilled destination than single or joint honours graduates of Post-92 universities. Even the lowest quintile graduates of the Russell Group had greater rates of highly skilled destination than the highest quintile from Post-92 universities, for both single and joint honours graduates. This demonstrated the positive impact that graduating from the Russell Group confers on both single and joint honours graduates. This study could not explain the much smaller gap in the highly skilled destinations between single honours and joint honours graduates found in the Russell Group, compared with the Post-92. Why do a higher proportion of joint honours graduates hail form the upper POLAR4 quintiles, the Russell Group joint honours graduates were more disproportionately from the upper POLAR4 quintiles and the joint honours upper POLAR4 quintiles represented such a larger proportion of the Russell Group overall undergraduate population? Other student characteristics such as tariff on entry, subjects studied, gender, age and ethnicity might all contribute to this finding. This study demonstrated that, averaged across all universities in the UK, there was a trend for both single honours and joint honours graduates from higher participation POLAR4 quintiles to be more likely to be in a highly skilled destination, i.e. the more educationally advantaged, were more likely to be in a highly skilled destination, as a proportion of the total from each honours type. This accorded with HESA (2018b) data, but expanded those findings to include direct consideration of joint honours graduates.
    • The effect of initial etching sites on the morphology of TiO2 nanotubes on Ti-6Al-4V alloy

      Danookdharree, Urvashi; Le, Huirong; Tredwin, Christopher; University of Plymouth (2015-07-14)
    • Effect of intermetallic compound layer thickness on the shear strength of 1206 chip resistor solder joint.

      Bernasko, Peter K.; Mallik, Sabuj; Takyi, Gabriel; University of Greenwich; Kwame Nkrumah University of Science and Technology (Emerald, 2015-02-02)
      Purpose – The purpose of this paper is to study the effect of intermetallic compound (IMC) layer thickness on the shear strength of surface-mount component 1206 chip resistor solder joints. Design/methodology/approach – To evaluate the shear strength and IMC thickness of the 1206 chip resistor solder joints, the test vehicles were conventionally reflowed for 480 seconds at a peak temperature of 240°C at different isothermal ageing times of 100, 200 and 300 hours. A cross-sectional study was conducted on the reflowed and aged 1206 chip resistor solder joints. The shear strength of the solder joints aged at 100, 200 and 300 hours was measured using a shear tester (Dage-4000PXY bond tester). Findings – It was found that the growth of IMC layer thickness increases as the ageing time increases at a constant temperature of 175°C, which resulted in a reduction of solder joint strength due to its brittle nature. It was also found that the shear strength of the reflowed 1206 chip resistor solder joint was higher than the aged joints. Moreover, it was revealed that the shear strength of the 1206 resistor solder joints aged at 100, 200 and 300 hours was influenced by the ageing reaction times. The results also indicate that an increase in ageing time and temperature does not have much influence on the formation and growth of Kirkendall voids. Research limitations/implications – A proper correlation between shear strength and fracture mode is required. Practical implications – The IMC thickness can be used to predict the shear strength of the component/printed circuit board pad solder joint. Originality/value – The shear strength of the 1206 chip resistor solder joint is a function of ageing time and temperature (°C). Therefore, it is vital to consider the shear strength of the surface-mount chip component in high-temperature electronics.
    • Effect of reflow profile parameters on surface mount chip resistor solder joint shear strength.

      Bernasko, Peter K.; Mallik, Sabuj; Takyi, Gabriel; University of Greenwich; Kwame Nkrumah University of Science and Technology (Science Publishing Group, 2014-09-30)
      The focus of this study is on the effect of reflow parameters on the joint shear strength. Eight reflow profiles were developed using four factors at two levels of Taguchi design of experiment for 1206, 0805 and 0603 chip resistors. Normal probability and main effect plots were used to provide a complete profile of the effect of reflow parameters on the chip resistor solder joint shear strength. The Normal Probability plots show effect of some reflow parameters on shear strength. Some data points did not fall on the best fit line.These outliers indicate parameter effects. The 1206 chip resistor shear strength value of 74.85N lies outside the best fit line indicating that some of the parameters are critical and significantly affect the response value. The results of the Main Effect plots help identify the unknown critical parameters in the probability plots. It indicates that the shear strength of 1206 chip resistor depends on the peak temperature, time above liquidus and preheat slope but not on cooling rate. In the case of the 0805 chip resistor, there were no exceptional departures from the line fitted to the data. It can be assumed that the factors and the levels considered here have no significant effect on the response. The normal probability plot of the 0603 chip resistor shows that the 46.68N shear strength lies outside the fitted line. This means that the factors and settings (run 3) can be further modified to improve the response. The factors which affected the 0603 resistor from the main effect plot are preheat slop and cooling rate.The results of the 1206 chip resistor show the highest shear force of 74.8 N using a peak temperature setting of 230°C (low level). The 0805 and 0603 chip resistors recorded the highest shear forces of 68.32N and 46.48 respectively using a temperature of 245°C (high level). The higher temperature may have contributed to the lower shear force due to the growth of brittle intermetallic compound in the case of the 0805 and 0603 chip resistors.
    • Effect of the building maintenance and resource management through user satisfaction of maintenance.

      Pontan, Darmawan; Surjokusumo, Surjono; Johan, Johny; Hasyim, Cholil; Setiawan, M. Ikhsan; Ahmar, Ansari Saleh; Harmanto, Dani; Tarumanagara University; Trisakti University; Darul Ulum University; Narotama University; Universitas Negeri Makassar; University of Derby (Science Publishing Corporation, 2018)
      PD Pasar Jaya manages 153 markets spread across Jakarta. Market building is a place of public services, in order to provide excellent service to the community, it is important to maintain it properly. Maintenance management of PD Pasar Jaya is still far from the expected. The purpose of this study was to determine the effect of directly and indirectly from the condition of the building and maintenance re-sources to user satisfaction through maintenance management. The research method is by taking a sample of 14 buildings market, then use the check list building condition assessment visually and dissemination of survey questionnaires to 216 respondents, namely the market manager, the kiosk, and visitors. The questionnaire consisted of four variables: the condition of the building (X1), maintenance resources (X2), as an variable, independent maintenance management (Y) as variable, an intervening while user satisfaction (Z) as the dependent variable. Furthermore, assessment data is processed by the descriptive analysis of the building, while the questionnaire survey data processed by path analysis using linear regression with SPSS ver. 22. The results of assessment of 14 buildings is a market average of 78 of the highest value of 100, this means that the condition of the building is being with only minor damage. The total yield of the influence of the condition of the building (42.38%) and maintenance resources (25.01%) towards satisfaction of a user through mainte-nance management (1.26%) is 68.65%
    • The effect of the inflation pressure of tyres on motorcycle weave stability: experiments and simulation.

      Cossalter, Vittore; Favaron, Valerio; Giolo, Enrico; Jomaa, Tarek; University of Padova (Taylor & Francis, 2016-08-03)
      Increasing the stability of a motorcycle requires an understanding of the optimal conditions of the tyre. The inflation pressure is one of the main parameters that directly affects the tyre properties, which in turn influences motorcycle stability and safety. This paper focuses on the effect of the inflation pressure of the tested tyres on motorcycle weave stability. Experimental data are collected from tests carried out in straight running at constant speed. The data analysis is based on stochastic subspace identification methods. Simulations are performed using an advanced motorcycle multi-body code with parameters measured from the tested vehicle. Finally, the comparison between simulations and experimental tests is discussed. The research results show an agreement between experimental tests and simulations where weave stability increases with inflation pressure for the specified range of tyre pressure.
    • The effect of thermal constriction on heat management in a microelectronic application.

      Ekpu, Mathias; Bhatti, Raj; Okereke, Michael I.; Mallik, Sabuj; Otiaba, Kenny; University of Greenwich (Elsevier, 2013-11-14)
      Thermal contact constriction between a chip and a heat sink assembly of a microelectronic application is investigated in order to access the thermal performance. The finite element model (FEM) of the electronic device developed using ANSYS software was analysed while the micro-contact and micro-gap thermal resistances were numerically analysed by the use of MATLAB. In addition, the effects of four major factors (contact pressure, micro-hardness, root-mean-squared (RMS) surface roughness, and mean absolute surface slope) on thermal contact resistance were investigated. Two lead-free solders (SAC305 and SAC405) were used as thermal interface materials in this study to bridge the interface created between a chip and a heat sink. The results from this research showed that an increase in three of the factors reduces thermal contact resistance while the reverse is the case for RMS surface roughness. In addition, the use of SAC305 and SAC405 resulted in a temperature drop across the microelectronic device. These results might aid engineers to produce products with less RMS surface roughness thereby improving thermal efficiency of the microelectronic application.