Dielectric studies of some oxide materials, nitride ceramics and glasses

This thesis is primarily concerned with the evaluation and comparison of the dielectric behaviour of materials which may find application as substrates in microelectronic high-performance packaging. In the introductory chapter the factors governing the choice of the most suitable dielectric substrate for compatibility with silicon technology are reviewed; it is shown that in addition to good dielectric properties the thermal conductivity is important if high power packages are required together with the ability to obtain good matching of thermal expansion coefficients. This is followed by a survey of the present theories of dielectric behaviour with special emphasis on the Universal law of dielectric response and its applicability to oxide and glass ceramics which exhibit hopping conductivity. The experimental methods for the measurement of dielectric parameters are outlined in Chapter 3 which includes an account of techniques developed for studying materials only available as powders. The three substrate systems studied were aluminium oxide, aluminium nitride and glass-on-molybdenum and in the case of the two former materials a range of both pure and impure specimens were examined both in single crystal and sintered polycrystalline form. The detailed experimental results are presented and discussed in the three succeeding chapters for each of the materials in turn; these results include the values of permittivity and dielectric loss, measured over a frequency range of 5 x 10(^2) Hz to 1 x 10(^7) Hz, the temperature variation of permittivity both in the low temperature (85K to 293k) and high temperature (20ºC to about 600ºC) regions and the d.c. and a.c. conductivity in the high temperature range. In their pure form each of these materials would be suitable as a substrate, having permittivities at room temperature of ϵ ' (_s) = 10.2 for polycrystalline Al(_2)(^0)(_3), ϵ' (_s) = 9.2 for polycrystalline AlN (which has a thermal conductivity of about one-hundred times that of alumina) and ϵ' (_s) - 6.5 for glass-on-molybdenum and dielectric losses in the region of tan δ - 10(^-3). The effect of impurities is shown to be very significant leading in all cases to some increase in permittivity and a much larger increase in dielectric loss. The measurements made on powders are given and discussed in Chapter 7. In the studies on the powders used as starting materials for the manufacture of substrates it was shown that by making measurements at low temperature (77K) the effects of intergranular space charge polarization could be overcome yielding information valuable for quality control of impurity content; measurements made on powders of some high temperature oxide superconducting materials are also given. The final chapter, Chapter 8, summarises the overall conclusions of the research and makes some suggestions for future work

Effektivitet, risiko og forvaltning av fiskerisektoren i Bangladesh

This dissertation consists of an introduction and five independent papers on Bangladesh fisheries sector. The first paper investigates how the fishery sector has developed and identifies the potential problems faced by the fisheries sector. Findings show that both fish production and productivity have increased for aquaculture and capture fisheries. Several problems, possible solutions and future prospects for fisheries sector are discussed in this paper. The second paper estimates the profitability and productivityfarm size relationship in aquaculture and investigates how smallholder farmers can sustain fish farming in the long run. It shows that the inverse profitability-farm size relationship holds but in general large fish farmers are more efficient, productive and profitable compared to small farmers. Access to credit and training are essential to sustain fish farming in the long-run. The third paper determines the production risk of pangas fish farming in Bangladesh. Results reveal that significant production risk exists in pangas farming. The use of large amount of fingerlings has risk increasing effects for all types of farms (small, medium and large farms) but feed usage is found to have a risk-increasing effect on production for large farms only, while the reverse holds in case of small farms. Findings suggest that access to credit and training in the fish farming can reduce production risk for smallholders. The fourth paper is on floodplain aquaculture where the impact on poverty and inequality of community-based aquaculture (CBA) system is investigated. We find that fish income and total household income is significantly and equally distributed after adopting this management system. Moreover, CBA management system can reduce the incidence and depth of poverty in the common resource areas. The fifth and last paper investigates whether excess capacity exists in gill-net fleet in the Bay of Bengal. If it does, then to what extent? And what are the policy alternatives for sustainable marine resource management? Results depict that the high degree of excess capacity exists in both monsoon and nonmonsoon seasons and more than one third of boats can be decommissioned. Licensing restrictions appear to be an effective instrument to eliminate the excess capacity from the fishery. However, this will have large distributional effects that need to be taken into account

Evolution of humanoid robot and contribution of various countries in advancing the research and development of the platform

A human like autonomous robot which is capable to adapt itself with the changing of its environment and continue to reach its goal is considered as Humanoid Robot. These characteristics differs the Android from the other kind of robots. In recent years there has been much progress in the development of Humanoid and still there are a lot of scopes in this field. A number of research groups are interested in this area and trying to design and develop a various platforms of Humanoid based on mechanical and biological concept. Many researchers focus on the designing of lower torso to make the Robot navigating as like as a normal human being do. Designing the lower torso which includes west, hip, knee, ankle and toe, is the more complex and more challenging task. Upper torso design is another complex but interesting task that includes the design of arms and neck. Analysis of walking gait, optimal control of multiple motors or other actuators, controlling the Degree of Freedom (DOF), adaptability control and intelligence are also the challenging tasks to make a Humanoid to behave like a human. Basically research on this field combines a variety of disciplines which make it more thought-provoking area in Mechatronics Engineering. In this paper a various platforms for Humanoid Robot development are identified and described based on the evolutionary research on robotics. The paper also depicts a virtual map of humanoid platform development from the ancient time to present time. It is very important and effective to analyze the development phases of androids because of its Business, Educational and Research value. Basic comparisons between the different designs of Humanoid Structures are also analyzed in this paper. ©ICROS

Quasi-inverse pendulum model of 12 DoF bipedal walking

This paper presents modeling of a 12-degree of freedom (DoF) bipedal robot, focusing on the lower limbs of the system, and trajectory design for walking on straight path. Gait trajectories are designed by modeling of center of mass (CoM) trajectory and swing foot ankle trajectory based on stance foot ankle. The dynamic equations of motion of the bipedal robot are derived by considering the system as a quasi inverted pendulum (QIP) model. The direction and acceleration of CoM movement of the QIP model is determined by the position of CoM relative to the centre of pressure (CoP). To determine heel-contact and toe-off, two custom designed switches are attached with heel and toe positions of each foot. Four force sensitive resistor (FSR) sensors are also placed at the plantar surface to measure pressure that is induced on each foot while walking which leads to the calculation of CoP trajectory. The paper also describes forward kinematic (FK) and inverse kinematic (IK) investigations of the biped model where Denavit-Hartenberg (D-H) representation and Geometric-Trigonometric (G-T) formulation approach are applied. Experiments are carried out to ensure the reliability of the proposed model where the links of the bipedal system follow the best possible trajectories while walking on straight path

Competitiveness and Growth Hindrances of Light Engineering Industry of Bangladesh: A Study on Micro, Small and Medium-Sized Enterprise (MSME) Owners

Indigenous light engineering talents of Dholaikhal and Jinjira have long been life line for the manufacturing industries and automobile sector of Bangladesh. Recent studies have shown that they are passing through hard times and the Government institutions are not supporting them to face the challenges and capture opportunities of their competitiveness and growth. First generation indigenous light engineering entrepreneurs have passed on the sector to the next generation. Much around them has changed. This study attempts to assess the major hindrances of achieving competitiveness and growth for the light engineering MSMEs in the changed scenario. A qualitative study was conducted through depth interview of the micro, small and medium sized LE enterprise owners, observation and validation workshop method. It looked beyond the words of the interviewees and read between the assembly lines of the factories. Findings show that the major hindrance to their competiveness and growth cultural factors, rather than popular view of resource scarcity. Keywords: Light engineering industry, micro, small and medium enterprises, growth and competitiveness, hindrance, Bangladesh, institutional role, need-delivery gap matrix.

COVID-19 media coverage and ESG leader indices

This study examines the dynamic connectedness between COVID–19 media coverage index (MCI) and ESG leader indices. Our findings provide evidence that MCI plays a role in facilitating the transmission of contagion to advanced and emerging equity markets during the pandemic. The connectedness between MCI and ESG leader indices is more pronounced around March and April 2020 at the peak of the pandemic. The US is a net receiver of shocks reaffirming that it was the most affected country during the pandemic. Our results provide implications for investors, portfolio managers, and policymakers in mitigating financial risks during the pandemic

Designing an algorithm for bioloid humanoid navigating in its indoor environment

Gait analyses are the preliminary requirements to establish a navigation system of a humanoid robot. Designing a suitable indoor environment and its mapping are also important for the android localization, selection of a goal to achieve it and to perform the assigned tasks in its surroundings. This paper delineates the various gaits like walking, turning, obstacle overcoming and step up-down stairs for a humanoid system. The writing also explicates the design of the indoor test environment with the stationary obstacles placed on the navigation routes. The development of an efficient algorithm is also excogitated based on the various analyses of gaits and the predefined map of the test environment. As the navigation map is predetermined, the designed algorithm animates the humanoid to navigate by selecting an optimal route, depending on some external commands, to reach at the goal position. Finally the performance of the system is analysed based on the elapsed time of the navigation action with the validation of optimal navigation strategy where the designed algorithm demonstrates the robustness of its implementation and execution

Cost Effective Broadband Access Network Using Wi-Fi over Passive Optical Network

Demand for broadband network is rapidly increasing the volume of data traffic from users. To meet this demand and provide customers with cost effective solutions, service providers concentrate mostly on the access network. Competition among the service providers leads to different broadband access technologies to serve customers with the best solution. Custom-ers’ demands for real time applications, as well as downloading of video and other applica-tions require high bandwidth allocation with high data rate. Also Governments put a sub-stantial influence in providing the cost effective solution to the different geographical loca-tion of country. As a result, service providers concentrate on minimizing the deployment cost for access equipment while maximizing the revenue from the service offerings. In this paper, we have proposed broadband access technology using Wi-Fi over Passive Optical Net-work(PON)to provide a cost effective solution considering geographical as well as economi-cal conditions. Introducing smart antennas such as narrow-beamwidth and switched array antennas can substantially improve the coverage distance for Wi-Fi access. For areas where the distance among houses is large, we propose to deploy Wi-Fi access instead of laying fi-bers. The optimization model to determine the number of Wi-Fi access points and to minimize the total cost of the network has been tuned to performance improvement

大豆発芽時期におけるグリシニン分解酵素の活性変動

　Changes in glycinin-digesting protease activity during soybean germination have been investigated. The glycinin-digesting protease activities of imbibed or germinated soybean seed were assayed by RP‒HPLC using a tryptic peptide from CM‒glycinin or by SDS‒PAGE using CM‒glycinin as the endogenous substrate. Proteolytic activities of the germinated soybean seeds were found through the whole period of germination, the activities were maintained significantly unchanged during germination for 4 days, and then those specific activities declined slowly. AE‒HPLC analysis of the glycinin-digesting protease in the imbibed or germinated soybean seeds showed unchanged peaks corresponding to glycinin- digesting activity, suggesting that the glycinin-digesting protease was not induced during germination but had already been synthesized during seed maturation.　大豆発芽期におけるグリシニン分解酵素 (98 kDa SBP) の活性変動を解析した．大豆種子を４時間水で膨潤後， 25 ℃ 暗黒下で発芽させた．経時的にサンプリングを行い，2M NaCl を含むトリス緩衝液 (㏗ 7.0) により粗酵素を抽出 後，グリシニン由来のトリプシン分解ペプチドを基質としてグリシニン分解酵素の活性変動を逆相 HPLC により追 跡した．その結果，種子膨潤後４日間比活性はほぼ一定の値を保ち，以後徐々に低下することが分かった．次いで， 粗酵素溶液からイオン交換 HPLC により98 kDa SBP を部分精製するとともに，発芽期における 98 kDa SBP の消長 を解析したところ，98 kDa SBP は乾燥種子及び各発芽段階の種子中全てに認められ，かつグリシン分解活性もグリ シニン由来のトリプシン分解ペプチド基質に対する活性と同様に認められた．以上の結果から，98 kDa SBP は種子 発芽に伴い誘導されるプロテアーゼではなく，種子貯蔵型のプロテアーゼであることが明らかになった

Stochastic modeling of production risk and technical efficiency of Thai koi (Anabas testudineus)farming in Northern Bangladesh

Thai koi is one of the high commercially valued farm fishes which have expanded tremendously in the northern part of Bangladesh. However, despite its impressive growth in the initial years, output of the industry is highly volatile across different years and farms. This research, following the Just and Pope framework, has made use of Kumbhakar’s (2002) extended stochastic frontier model (SFM) to estimate production risk and technical efficiency (TE) in Thai koi farming. Results show that feed is the most important input significantly influencing production. Zeolite and pesticide appear to be risk-reducing, while fingerlings, labor, feed and salt turn out to be risk-increasing inputs. The inefficiency model indicates that labor and pond area significantly reduce the technical inefficiency. Feed, fingerling and lime also act as TE-improving factors. Education of farmers improves TE, while experience, training and frequency of water change do not impact the TE. The mean TE scores are 0.73 and 0.96 for the flexible risk estimate and conventional SFM estimates, respectively. TE values appear to become exaggerated when production risk is excluded from the model. SFM recognizes that risk is involved in Thai koi farming that causes lower TE