Parametric modelling of Malaysian teeth template using computer aided design

This study explored a new method and process of design denture using CAD technology to develop a template of a complete denture. Computer aided design were used as a tool of the design process. Occlusion curve was set up as variable as to follow patient size. The maxilla and mandible teeth arrangement were treated as a template of Malaysian user. The accuracy of design is the main aspect of concern that match the patients' data so that the outcome product would be suitable with maximum comfort for the patient. The product of design template will be matched with the conventional method to compare the tolerance between both. The new design template helps to reduce the time consumption of conventional carving method. The final output of 3D geometry teeth templates design will represent the patient details

Improving the performance of QoS models in MANETs through interference monitoring and correction

Mobile Ad hoc Networks (MANETs) have been proposed for a wide variety of applications, some of which require the support of real time and multimedia services. To do so, the network should be able to offer quality of service (QoS) appropriate for the latency and throughput bounds to meet appropriate real time constraints imposed by multimedia data. Due to the limited resources such as bandwidth in a wireless medium, flows need to be prioritised in order to guarantee QoS to the flows that need it. In this research, we propose a scheme to provide QoS guarantee to high priority flows in the presence of other high as well as low priority flows so that both type of flows achieve best possible throughput and end-to-end delays. Nodes independently monitor the level of interference by checking the rates of the highest priority flows and signal corrective mechanisms when these rates fall outside of specified thresholds. This research investigates using simulations the effects of a number of important parameters in MANETs, including node speed, pause time, interference, and the dynamic monitoring and correction on system performance in static and mobile scenarios. In this report we show that the dynamic monitoring and correction provides improved QoS than fixed monitoring and correction to both high priority and low priority flows in MANETs

Sensor material characterisation for magnetometer application

Pengukuran dan gangguan medan magnet arus terus dan arus ulang-alik memerlukan penderia medan magnet yang mempunyai kepekaan yang tinggi dan stabil. Untuk menghasilkan penderia tersebut, ciri-ciri bahan magnet yang baik telah dikenalpasti. Beberapa jenis bahan magnet yang berbeza telah digunakan untuk mengkaji ciri-ciri dan kesannya terhadap medan magnet. Teras gelang yang diperbuat daripada bahan-bahan magnet tersebut direkabentuk dengan dimensi yang sama bagi membolehkan perbandingan dibuat dengan mudah. Selain itu, rod tunggal dan berkembar juga telah digunakan sebagai teras penderia fluxgate, untuk melihat prestasi setiap jenis penderia tersebut. Kedua-dua penderia tersebut telah diuji dengan menggunakan dua sumber bahan magnet iaitu bar magnet tetap dan solenoid dengan diameter dawai yang berbeza. Isyarat keluaran bagi setiap penderia fluxgate seterusnya diproses bagi mengenalpasti hubungannya dengan ketumpatan medan magnet

FDM preparation of bio-compatible UHMWPE polymer for artificial implant

Due to its properties of high wear, creep resistance, high stiffness and strength, Ultra-High Molecular Weight Polyethylene (UHMWPE) was developed to eliminate most metallic wear in artificial implant, which conventionally found in stainless steel, Cobalt Chromium (Co-Cr) and Titanium (Ti) alloys. UHMWPE has an ultra-high viscosity that renders continuous melt-state processes including one of the additive manufacturing processes, Fused Deposition Modeling (FDM) ineffective for making UHMWPE implant. Attempt to overcome this problem and adapting this material to FDM is by blending UHMWPE with other polyethylene including High Density Polyethylene (HDPE) and Polyethylene-Glycol (PEG) which provide adequate mechanical properties for biomedical application along with the improvement in extrudability. It was demonstrated that the inclusion of 60% HDPE fraction has improved the flowability of UHMWPE in MFI test and showing adequate thermal stability in TGA

A novel approach to the design of DSP systems using minimum complexity Finite State Machines

The paper presents a new and different approach to the design and realisation of Digital Signal Processing (DSP)systems by utilising Finite State Machines (FSM). The DSP system is modelled by mapping all its potential states into an FSM, whose complexity is usually very high. The FSM mirrors the complete functionality of the system and thus describes its behaviour in full detail. Examples for FSMs of first and second order digital recursive filters are provided and the current version of the software simulating the FSM corresponding to any linear time-invariant DSP system is described. The potential of this approach including state reduction techniques as well as the inclusion of non-linear DSP systems is also outlined, and further future research intentions are briefly explored

Selective Laser Sintering of Polymer Nanocomposites

This paper describes the fabrication and characterization of polymer nanocomposite (PNC) materials for use in the selective laser sintering (SLS) process. PNC materials are of great interest generally because of their excellent physical properties, and offer excellent potential in rapid manufacturing of structural polymeric parts. Three different nano additive materials have been used: cerium oxide IV, yttrium stabilized zirconia, and layered Hectorite clay. These materials have been used to reinforce PA6 polymer using solution blending and spray drying to create powder with particle sizes in the range of 5-40 µm. The mechanical properties and microstructure of the PNC materials have been evaluated and the results compared to those of unfilled polymer.Mechanical Engineerin

Experimental and numerical investigation into effect of elevated temperature on fretting fatigue behavior

Fretting fatigue damage occurs in contacting parts when they are subjected to fluctuating loadings and sliding movements at the same time. This phenomenon may occur in many applications such as bearings/ shafts, bolted and riveted connections, steel cables, and steam and gas turbines. In this paper, the effect of elevated temperature on fretting fatigue life of Al7075-T6 is investigated using a new device for fretting fatigue tests with variable crank shaft mechanism. Also a finite element modeling method was used to estimate crack propagation lifetime in aluminum alloy, Al7075-T6 specimens at elevated temperature under fretting condition. In this method, shear and normal stresses that are caused by contact load are updated at each crack growth increment. Finally, a comparison between the experimental and numerical results is done in order to evaluate the FE simulation. Department of mechanical engineering, Islamic Azad University, Takestan Branch, Takestan, Iran The experimental results show that: (i) fretting fatigue life of the material increases with temperature up to 350°C by 180% for low stresses and decreases by 40% for high stresses, (ii) this fashion of variation of fretting fatigue life versus temperature is believed to be due to degradation of material properties which occurs by overaging and wear resistance increase due to oxidation of aluminum alloy. While overaging gives rise to degradation of mechanical strength of material and hence the reduction of its fretting fatigue life, surface oxidation of the specimens brings some improvement of fatigue behavior of the material. Metallurgical examination of the specimens reveals that temperature results in precipitation of impurities of al-7075-T6. The size of precipitated impurities and their distances gets bigger as temperature increases. This could be a reason for material degradation of specimens which are exposed to heating for longer time duration