Structural analysis of long arm excavator boom for optimization performance under maximum breakout condition

Long Arm Excavators are widely used in the construction site for excavating deep holes or trenches. However, due to the often-severe work conditions, such as large lifting loads, poor ground conditions to sustain the machine’s self-weight, Long Arm Excavator parts are subjected to constant wear and tear, incurring downtime losses and safety issues. The boom is considered the most critically affected part of the machine in these work conditions, where the high forces and unpredictable elements at the worksite could severely affect the machine’s overall performance. A potential solution is the reinforcement of the boom to improve its robustness. As an industrial collaborative project, the present study examines the performance of an existing machine with simulated improvement of the boom with such an approach, i.e. incorporation of stiffener reinforcement. Simulation works were carried out with Ansys Workbench 19.2 to assess the boom’s performance in terms of resulting stress, strain and deformation under a series of improved conditions, which include varying the dimensions and positions of the stiffeners on the boom. The improved conditions were Improvement I: stiffeners thickness reduction to 10mm, Improvement II: a combination of different stiffeners thickness reduction which 10mm and 8mm at critical and non-critical part of the boom, Improvement III: removal of half intermediate stiffeners thickness 12mm and Improvement IV: removal of half intermediate stiffeners thickness 8mm. Structural analysis was conducted based on the maximum breakout condition in which the excavator generates maximum digging force. From the analysis, it was found that the maximum equivalent stress of the boom decreased with the number of stiffeners. The combination of different stiffeners thickness could also increase the boom’s strength while decreasing the maximum equivalent stress. The lowest maximum equivalent stress of the boom was achieved via Improvement II with a reduction of 26.1% maximum equivalent stress. Removal of non-critical part stiffeners also kept stress values under the designated stress limits against fatigue failure, i.e. 44.49 MPa and 42.47 MPa (Improvement III and IV). In summary, the optimal design could be obtained with improvement II. This would effectively save on the manufacturing costs while maximizing the machine’s performance on-site, simultaneously reducing downtime and hence operating costs and time

Open University Malaysia's Market Driven Approach in Fulfilling Varying Needs of Adult Learners

Open University Malaysia (OUM) is only in her seventh year of operations, but she has carved a niche in an increasingly competitive market. With a mere enrollment of 721 when she first open her doors in August 2001, the corresponding figure stood at 65,384 students in September 2007, recording a compound growth rate of about 40 percent per annum. In terms of geographic concentration, apart from the capital city of Kuala Lumpur and its vicinity, other exceptionally high growth areas are the marginalized populace of the states of Kelantan, Sarawak and Sabah. She has also sailed beyond - to Bahrain, Yemen and islet of Indonesia. Negotiations are also underway for her programs to be offered in a couple of other countries which had learnt of OUM's mark in her expressed market. The key to OUM's success had primarily been the application of market-driven strategies in each of the segments she operates. Though OUM is relatively new, distance education is not. OUM took a strategic approach to determine the existing misfits and formulated alternative ways of addressing them. In the process, OUM was able to serve the latent need of the market with offers that represents a blend of the wisdom of renowned providers adapted to the local legal and socio-cultural constraints imposed upon it. Though resource-tight, OUM took a national roll-out plan which conventionally required formidable investment in facilities and manpower to create her felt-existence and ensure prompt service delivery. She side-stepped those requirements with a network of varying strategic alliances with customers and what would have been potential competitors. At the micro level, access to tertiary education to students from the country's hinterland, with grossly inadequate transportation and telecommunication tools, would have been denied if OUM had not stretched the strategic approach beyond conventional imagination. She abandoned, to better serve this niche, the tested standard blended mode which incorporates complementary regular fortnightly face-to-face sessions. Instead, a modified blended mode of delivery, slanted more to group independent learning was formulated. This paper, in part, presents the profile of this unique micro-segment, describes the modus operandi of the customised delivery mode and discusses its effectiveness in OUM�s endeavour to serve the marginalised group of students

Sb2Te3 crystal a potential absorber material for broadband photodetector: a first-principles study

Antimony telluride (Sb2Te3), a layered semiconductor material, is considered a promising absorbing material for a high-performance optoelectronic device within broadband wavelengths because of remarkable features like strong optical absorbance and the narrow direct band gap. In this work, based on the first-principles approach, we investigate in detail the structural, electronic and optical properties of the hexagonal Sb2Te3 compound. The structural and electronic properties were computed using the first-principles approach, treating exchange–correlation potential with generalized gradient approximation (GGA) within density functional theory (DFT). Furthermore, for accurate prediction of the band gap, we go beyond DFT and calculated band structure using GW correction. The optical properties, namely, imaginary and real parts of complex dielectric function, absorption coefficient, refractive index, reflectivity, extinction coefficient, electron energy loss function and optical conductivity are performed by quasi-particle many-body perturbation theory (MBPT) via Bethe-Salpeter equation (BSE). The computed structural parameters are in good agreement with available experimental data. The obtained quasi-particle (GW) correction band structure show the semiconducting character of Sb2Te3 material with a direct band gap Eg of 0.221 eV, in agreement with previously reported value (Eg = 0.210 eV) while the projected density of states indicates (PDOS) that the p-orbital of Sb and Te atoms are responsible for material properties near the Fermi level. To our knowledge, our first reported calculations of optical properties, with the inclusion of electron-hole effects are consistent with available experimental measurements. Consistencies of our findings with experimental data validate the effectiveness of electron-hole interaction for theoretical investigation of optical properties

Electronic and optical properties of Bi2Se3 topological insulator: a promising absorbing layer for broadband photodetector

Bismuth selenide (Bi2Se3) is a van der Waals compound which has been excellently reported as thermoelectric material. Linear dispersion near Fermi energy level is an exciting feature to consider, a promising candidate for photonic device within broadband wavelengths. For this application, detailed knowledge of its structural, electronic and optical properties is very essential. The electronic properties were determined by density functional theory (DFT) calculations implemented in Quantum-Espresso simulation package which uses plane wave basis and pseudopotential for the core electrons. Optical properties are computed by solving Bethe-Salpeter equation of many-body perturbation theory (MBPT) as implemented in Yambo code. The band structure results show the semiconducting behaviour of Bi2Se3. Taken into account the effects of electron-hole interaction by solving Bethe-Salpeter equation, the calculated optical properties are in better agreement with available experimental results. The exciton energy shows that the title material can absorb light within infrared region

Linear acenes linked thiophene, electronic and chemical properties: Prospects for molecular organic electronic material

We report a theoretical study of linear acene (n=1 to 7) linked thiophene properties functionality. The total ground state and band gap energies, Coulomb potential and nuclear repulsion energy are calculated by DFT, MP2 at B3LYP exchange level of the theory and 6-311G* basis set. The results are in good agreement with the experimental and theoretical values. It is found that the total ground state energy of the system and band gap energy decreases with an increasing number of electrons in the rings. The addition of thiophene molecules tends to improve the electronic and chemical properties of the linear acenes, the material exhibit potential application in the organic molecular electronic material

Excellent educare tuition centre / Marsytah Shaari... [et al.]

Committing to the business domain expressly in education directly will help the Ministry Of Education to increase the education level or standard in Malaysia. Barrel to the government’s aspiration is to produce the educated and excellent younger for the new millennium era. That is why we come out with this business in order to overcome the barrel. Apart from that, in order to realize the government's encouragement, to increase the number of excellent students in our country, to increase the quality of education and to produce more expertise and professional in fieldwork, therefore we come out with this business. Based on the objectives of Excellent Educare Tuition Centre, we will provide a space for the USPR, PMR, SPM & STPM candidates and also for those are the former students (repeaters ), to improve their quality of studies. Besides that, we come out with the latest technology approach, meaning that our services are totally technology-oriented. The teachers will conduct the learning session using the projector and laptop. This will be the best way to attract student's attention and will avoid the feeling of the bore during the learning session. These actually comply with our target to establish the best learning condition for the student

Gender Dependence in Mouth Opening Dimensions in Normal Adult Malaysians Population

While measurement of mouth opening is an important clinica examination in diagnosis and management of oral disease, data on non-Western populations are limited. This study was therefore conducted to determine the range of mouth opening in normal Malaysian male and female adults. A total of 34 dental students of Universiti Sains Malaysia (USM) were chosen randomly and their maximum mouth opening was measured after being asked to open their mouth sufficiently to accommodate three fingers. Measurement was performed from the edge of the upper incisor to the lower incisor using a caliper divider. The difference of median values between male (47.6 mm) and female (40.8 mm) were significant respectively (p<0.05). Thus the width of mouth opening in Malaysian student population is gender dependent although further study with a larger sample size and with other ethnic groups should be carried out, focusing on age

The study of optical gain for terahertz quantum cascade laser using density matrix method

Terahertz (THz) quantum cascade lasers (QCL) are currently increasing in popularity. It is expected to become the main source of emerging terahertz radiation technology and applications. However to produce the device within the application specification is costly and time consuming. This is because the manufacturing process of the superlattice growth and the device processing and testing are long and expensive processes. Thus a prediction tool is needed to overcome the problems in designing and producing THz QCL within the needed optical expectation. The density matrix method is used to calculate the performance of this device electronically and optically. The result obtained was compared to the experimental result conducted by previous researchers. The calculation result showed that the gain is 20 cm−1 when the population inversion occurs at threshold current density of 400 A cm-2. Meanwhile a negative gain or loss occurs below 350 A cm-2. As a conclusion, it is demonstrated that this method has a capability to explain the transport phenomena as well as to predict the performance of the THz QCL device design

Ground state energy, electronic and chemical properties: an investigation of linear acenes (n=1 to 7) linked thiophene for organic electronic material

We report a theoretical study of linear acene (n=1 to 7) linked thiophene functionality. The total ground state energies, HOMO-LUMO energy gap, frontier orbitals energies, electron affinity and ionization potential are calculated at DFT-B3LYP/6-311G* and MP2/6-311G* exchange level of the theory and basis set. The results show a good agreement when compared with the theoretical and experimental values. It is found that total ground energy of the system, HOMO-LUMO gaps energy, electrophilicity, electronegativity and chemical hardness decrease with the increasing number of electrons or acenes ring. The global chemical indices; electronegativity (χ) , electrophilicity (ɷ) and chemical hardness (ɳ) is observed to decrease as the number of electrons in acenes ring increase, whereas softness(S) and chemical potential (µ) increases with the increasing number of electrons around molecules. Also, the frontier orbital energies, Ionization energies, and electron affinity results show an improvement as compared to the acenes molecules