Printing conductive traces to enable high frequency wearable electronics applications

With the emergence of the Internet of Things (IoT), wireless body area networks (WBANs) are becoming increasingly pervasive in everyday life. Most WBANs are currently working at the IEEE 802.15.4 Zigbee standard. However there are growing interests to investigate the performance of BANs operating at higher frequencies (e.g. millimetre-wave band), due to the advantages offered compared to those operating at lower microwave frequencies. This thesis aims to realise printed conductive traces on flexible substrates, targeted for high frequency wearable electronics applications. Specifically, investigations were performed in the areas pertaining to the surface modification of substrates and the electrical performance of printed interconnects. Firstly, a novel methodology was proposed to characterise the dielectric properties of a non-woven fabric (Tyvek) up to 20 GHz. This approach utilised electromagnetic (EM) simulation to improve the analytical equations based on transmission line structures, in order to improve the accuracy of the conductor loss values in the gigahertz range. To reduce the substrate roughness, an UV-curable insulator was used to form a planarisation layer on a non-porous substrate via inkjet printing. The results obtained demonstrated the importance of matching the surface energy of the substrate to the ink to minimise the ink de-wetting phenomenon, which was possible within the parameters of heating the platen. Furthermore, the substrate surface roughness was observed to affect the printed line width significantly, and a surface roughness factor was introduced in the equation of Smith et al. to predict the printed line width on a substrate with non-negligible surface roughness (Ra ≤ 1 µm). Silver ink de-wetting was observed when overprinting silver onto the UV-cured insulator, and studies were performed to investigate the conditions for achieving electrically conductive traces using commercial ink formulations, where the curing equipment may be non-optimal. In particular, different techniques were used to characterise the samples at different stages in order to evaluate the surface properties and printability, and to ascertain if measurable resistances could be predicted. Following the results obtained, it was demonstrated that measurable resistance could be obtained for samples cured under an ambient atmosphere, which was verified on Tyvek samples. Lastly, a methodology was proposed to model for the non-ideal characteristics of printed transmission lines to predict the high frequency electrical performance of those structures. The methodology was validated on transmission line structures of different lengths up to 30 GHz, where a good correlation was obtained between simulation and measurement results. Furthermore, the results obtained demonstrate the significance of the paste levelling effect on the extracted DC conductivity values, and the need for accurate DC conductivity values in the modelling of printed interconnects

A new home for the hornbills

SABAK BERNAM: Welcome to the land of the Hornbills - and no, it's not in Sarawak. Kampung Sungai Panjang here has been playing host to hornbills which have made the village their roosting ground

Overview of the sensitivity of Ge- and Al-doped silicon dioxide optical fibres to ionizing radiation

This paper reviews the thermoluminescence sensitivity of Ge- and Al- doped SiO2 optical fibre subjected to various ionizing radiations. It is found that the Ge- doped SiO2 optical fiber has the thermoluminescence response superior to Al-doped SiO2 optical fibre at certain energy and dose range in alpha, beta, photon and electron irradiation. High thermoluminescence intensity per unit dose goes to photon and electron irradiation than alpha and beta irradiation of lower energy. This probably due to the linear energy transfer that influence the dose deposition in the material as incident ionizing radiation striking the surface of Ge- and Al- doped SiO2 optical fibre. However, both doped SiO2 optical fibres show good linearity at studied dose range. It has been proven by researchers providing great potential as a dose absorbed measuring devices especially in radiotherapy energy and dose rang

Effects of Grain Refinement on The Cooling Rate, and Microstructural and Mechanical Properties of Al-Si Sand Castings

This thesis covers the key areas of numerical simulation of sand casting process to evaluate the runner and gating system of sand mold. The major experimental work is focused on grain refinement and modification of LM6 A1-Si sand casting. The simulation software package used is MAGMAsoft and the sand casting process employed is COz sand casting. The numerical results of MAGMAsoft match qualitatively with the experimental data. This validates the use of MAGMAsoft to simulate sand casting process to assist in mold design and prediction of flow and solidification characteristics. The implementation of experimental work to ascertain flow and solidification characteristics of sand casting has been performed on a casting designed with varying thickness of different moduli. The casting metal used is LM6 A1-Si alloy. The cooling rate of sand casting has been correlated with the modulus of casting. The mechanical mechanical properties of hardness and ultimate tensile strength have been correlated with the solidification rate. The secondary dendrites arm spacing (SDAS) is also found to have linear correlation with section modulus. This provides important and useful information to product design of sand casting about how to optimize the section thickness to achieve the desired mechanical properties. An investigation is carried out to study how to further enhance the mechanical properties of LM6 A1-Si alloy sand casting by adding the commercial grain refiner of Al-5Ti-1B into the melt at different inoculation levels of 0.25, 0.5, 0.75 and 1.0% weight. The results show that 0.5% weight of A1-5Ti-1B grain refiner is the optimal level to grain refine and enhance the mechanical properties of LM6 sand casting. The microstructural analysis shows that grain size is reduced when the casting solidifies with faster cooling rate due to the addition of grain refiner. This renders significant effect to enhance the mechanical properties of the casting. The improvement of grain refinement is quantified by measuring the hardness, ultimate tensile strength (UTS) and elongation (strain) of the cast samples. Inoculation with 0.5% weight of Al-5Ti-1B grain refiner has attained UTS of 167.86 MPa, maximum hardness of 65.6 Rockwell and fracture strain of 0.0314. A further investigation has been carried out to add 0.5% weight of A1-1OSr and 0.5% weight of Al-5Ti-1B into the melt to cast the same part. Similar mechanical tests and microstructural analysis are performed to study the combination effect of strontium, titanium and boron on LM6 sand castings. It is discovered that the ultimate tensile strength of the castings is further improved to 174.46 MPa and the morphology has been modified. However, the hardness of Sr-modified LM6 sand casting only achieves a maximum value of 63.34 Rockwell which is not a significant improvement. Modification of LM6 by strontium only alters the morphology of the silicon eutectic to be more fibrous instead of acicular so that the structure would not be brittle relative to unmodified structure and it is found that the ductility after modification achieves a fi-acture strain of 0.032 which is higher than the 0.0267 of unmodified LM6. The cooling curve shows that the solidification is dramatically transformed to eutectic solidification at temperature around 540 O C . This mixture of grain refiner and modifier is termed "hybrid modifier" by the author

Rainfall Characteristics and Its Effect on Road Infrastructure Health

Malaysia has a strategic geographical location in which it is protected from most of natural disasters such as earthquakes and typhoons. However, it is affected by flood which is a common occurrence in Malaysia. There is a direct relationship between rainfall and flooding as the increase in rainfall intensity would produce higher runoff. This research is first focused on the four rainfall stations located at the Northeast District of Penang Island, in which its rainfall pattern was determined from 2007 to 2016 and geospatial data analysis has been done by using ArcGIS. The occurrence of flood is found to have great impact on the road infrastructure health. Next, soil commonly used for road foundation (subgrade) in Malaysia was used to investigate the effect of moisture content on subgrade strength, in which the California Bearing Ratio (CBR) test was carried out with increment of moisture content. The findings indicated that the rainfall pattern in Northeast District of Penang Island was affected by the monsoon seasons, in which the Southwest Monsoon brings in more rainfall from April to September. The extreme rainfall during the Southwest Monsoon caused flood to frequently occur in the study area. Total rainfall in the area indicated a decreasing trend in which the total annual rainfall of the latest five years is less than that of the first five years, from 2007 to 2016. However, the intensity of rainfall can be seen on the increasing trend and this is expected to cause greater soil exposure to moisture. The CBR strength of soil is found to be reduced with the increasing moisture content, as the soil bearing capacity is reduced when the soil become saturated. The reduction in subgrade soil’s bearing capacity will affect the performance of the road systems

Entrepreneurial design of a digital health business

Software startups are an important source of innovation and wealth creation. Startups must develop and release software quickly to gain early cash flow and legitimacy for firm survival. They must search and identify a suitable market in a tight time frame. A ambiguity in the quality of the novel software designed can further intensify uncertainty for startups. Also, the entrepreneur-investor relationship is a critical conduit for financial and social resources, yet the investors’ influence on software design is understudied. This leads to the following research question: How does the entrepreneurial context in which the startup operates affect software design process and product in the early years? Given the exploratory nature of the research question, I drew on an eighteen-month, participant-observation case study of a three-year-old, digital healthcare startup, HealthCom. HealthCom designed a software to facilitate knowledge transfer between nurses and patients. I leveraged the attention-based view (ABV) as an organizing framework for analysis. By looking at how the environmental context influences the designers’ attention and actions, researchers can begin to understand the rationale behind design decisions. The findings illustrate how the attention of the designers were directed by financial-focused and quality-focused attention drivers. Financial-focused attention drivers originated from players (e.g. clients and investors) that intensified pressures for funding and led to the reframing of software as an enabler of funding. This contradicted quality-focused design alternatives grounded in user requirements and software design rules. It underlined the move from attention to designs that accommodated user requirements towards those that captured emerging business opportunities. Designers had to balance the tensions between financial and quality-focused design decisions that could lead to inhibition of future growth, compromises in quality or over-optimization of quality. Designers simplified and coupled requirements throughout the design process and postponed investments of design resources to meet client-imposed deadlines. The design product became disposable, quick to build, limited in adaptability, spartan, and vulnerable, and it enabled the startup to capture the business opportunities amidst time constraints, financial pressures, and high uncertainty.Information, Risk, and Operations Management (IROM

Arima and integrated Arfima models for forecasting annual demersal and pelagic marine fish production in Malaysia

The seas surrounding Malaysia provide a rich source of marine fisheries. The fisheries industry is an important economic earner and the total marine fish production has increased drastically from 242,900 metric tonnes in 1970 to around a million metric tonnes in the year 2000. Since fisheries resources are renewable, proper management issues should be taken to manage these fisheries resources. From the management point of view, fish forecasting is a very important tool for fisheries managers and scientists to enable them to decide on sustainable management issues. Time series models have been used to forecast various phenomena in many fields. In a previous research by Mahendran Shitan et. al. (2004), the maximum likelihood and bootstrap method were used to forecast the total Malaysian marine fish production. Marine fish can be sub-classified as demersal marine fish and pelagic marine fish and it would be interesting to forecast the individual composition of these categories. Therefore, in this research we fit time series models to forecast the demersal and pelagic marine fish production using ARIMA and integrated ARFIMA models and make predictions of each category. Our results indicate that the ARIMA models appear to be the better models and the forecasted amounts for the year 2011 are approximately 373,370 and 666,460 metric tonnes for the demersal and pelagic marine fish, respectively

Radiotherapy in Lung Cancer

Lung cancer remains one of the top five cancers worldwide. Around 85% are nonsmall cell lung cancer (NSCLC) and only one‐third present with early stage diseases. Radiotherapy had an important role both in radical and palliative treatment. With advancement in technology, newer techniques of stereotactic body radiotherapy allow delivery of much higher biologically effective dose to tumor achieving similar outcomes to radical surgery in early stage diseases. However, the usually large tumor volume together with preexiting poor lung condition makes radiotherapy challenging to deliver a radical dose to tumor while maintaining normal tissue constrains. In this chapter, different indications and techniques used in treating NSCLC will be discussed and reviewed

Carbon Doped Silicon Dioxide Low K Dielectric Material.[QC585.75.S55 L732 2004 f rb][Microfiche 7649]

Objektif kajian ini adalah untuk mengkaji keberkesanan mendopkan sebatian karbon keatas SiO2 untuk menghasilkan bahan dielektrik k rendah. The semiconductor industry is entering a new millennium where scientists and engineers are continuing to search for the ideal dielectric material for future chip fabrication