Engineering

The mean glandular dose (MGD) was measured for a breast phantom by using molybdenum/molybdenum and molybdenum/rhodium target/filter combinations, at different kVp 26, 28 and 32 kilovolts. The phantom thickness was 7.5cm and was made of BR12 material. The change of dose was studied as a function of depth inside Contents ABSTRACT .

Zinc oxide (ZnO) has long been described as a radiation hard material, but there was not enough interest taken in previous researches to study the effect of radiation on the ZnO, especially the irradiation at room temperature. This study was designed to test the radiation hardness properties of ZnO by using different ionising radiation types. The main interest is in investigating the effect of neutrons on the optical properties of the zinc oxide. Two types of samples were studied: pure ZnO single crystal bulk and ZnO crystal bulk with gadolinium (Gd) implanted into its Zn-polar face (Gd:ZnO). Each type of sample was exposed to slow and fast neutron radiation for a time interval that varied between minutes and days depending on the sample type. Slow neutron irradiation was carried out using 241Am-Be sources supplied by the University of Canterbury, which were placed under a 4.5 cm thick wax moderator, with a resultant flux of 1.5 × 106 n/s.cm2. The clinical neutron therapy system (CN...

Physics is an essential subject for most fields of study within science and engineering. Students cannot master it by simply watching their lecturer solving the problems at the end of each chapter, they must fully engage in solving these problems. However, in order to solve these problems students must be able to extract the information from the problems necessary for setting up the equations. This often requires that they visualize the problem, and that skill can present quite a challenge for some, and especially students who are studying physics in a second language. The aim of this study was to investigate the effects of the ability to visualize physics problem on students' success in answering physics exam questions. Twenty-eight undergraduate and 10 preparatory students were randomly assigned to participate in this study and asked to solve physics problems related to their mechanic's physics course. These problems contained a few sentences of English text which described a situation or image, and students were asked to draw the scenario or image described in the text. The result of the study highlights the difficulty in solving physics questions faced by students who lack the ability to visualize and the importance of training students to visualize physics problems in order to help them solve problems and to enhance their understanding of the physics concepts.

This study investigates the effect of neutron irradiation on zinc oxide (ZnO) crystal bulk substrates that have been ion-implanted with gadolinium (Gd) and iron (Fe) in different concentrations in the Zn-polar (0001) face of the crystal to produce Gd:ZnO and Fe:ZnO crystal bulk samples. The neutron beams of the 241 Am−Be flux were moderated to be 7 × 10 4 n/s cm 2 by a 4.5 cm-thick wax. The implanted face was left to face the neutron beams on top of the wax for 90 h. The results show that the nuclear reaction between thermal neutrons and the implanted material produced a large amount of heat, which significantly enhanced the photoluminescence spectra of the crystal bulk surface after the surface damage caused by ion implantation. This study provides insights into the benefits of having a doped material in the ZnO crystal after irradiation and highlights the potential of neutron irradiation as a method for enhancing the properties of implanted crystal bulk substrates.

The aim of this study is to identify effective intervention activities in the physics classroom that enhance student engagement and sustain attention toward learning physics by evaluating the impact of diverse strategies on student motivation.

The study involved the growth of zinc oxide (ZnO) by molecular beam epitaxy
(MBE) film on a c-plane sapphire (Al2O3) substrate, followed by ion implantation
of gadolinium (Gd) at a concentration of 4 9 1015 ion/cm2 to a depth of
20 nm to produce GdZnO. Subsequently, the film was subjected to neutron
irradiation using a 241Am-Be flux that was moderated to 7 9 104 n/s cm2 by a
4.5-cm-thick wax. The neutron irradiation was conducted continuously for
7 days. The thermal energy generated from the neutron irradiation with Gd
was sufficient to create a compound between the Gd and Al taken from the
substrate, resulting in the formation of a GdAl2 crystal. This is due to the
nuclear reaction between the thermal neutrons and Gd, which provided the
energy needed to initiate the reaction. In addition, the reaction between Gd
and Al resulted in the displacement of the indium (In), used as a dopant for
ZnO fabricated by MBE, from the Gd site to the Al site, causing the Al exciton
line to become the dominant near-band-edge emission.

Physics is an essential subject in most fields of Science and Engineering which cannot be mastered simply by watching lectures or solving problems at the end of each chapter: students must fully engage in solving these problems. This often requires problem visualisation, which presents quite a challenge for some, especially for students who are studying Physics in a second language because their understanding of the question can be influenced by the gaps in their understanding of the language used. The focus of this study is to investigate the role the language used in the wording of Physics problems plays in students’ ability to understand the question and accurately visualise the scenario that would be needed to extract the required information. 220 undergraduate students and 80 preparatory students volunteered to participate in this study. Students were asked to read two sets of Physics problems and to draw the scenario or image described in the text. The first set used the more advanced English that is commonly found in Physics textbooks and which includes passive voice and homonyms, while the other uses active voice and more simplified English. The results of the study highlight the fact that ESL students’ struggle with certain types of advanced English used in Physics such as the passive voice, showing that they are more capable of translating text into images when active voice is used.

21 20 11TH INTERNATIONAL RESEARCH CONFERENCE GENERAL SIR JOHN KOTELAWALA DEFENCE UNIVERSITY 11TH INTERNATIONAL RESEARCH CONFERENCE GENERAL SIR JOHN KOTELAWALA DEFENCE UNIVERSITY Based on the findings of this research, the researchers have found that despite the immense contribution made by both organizations towards the aviation industry in Sri Lanka, proper utilization of available human and technical resources are not utilized to the fullest potential to achieve better productivity. Improvements to overall maintenance effectiveness can be achieved by inculcating a more disciplined work environment where rules and regulations with regard to technical work are more stringently imposed and facilitating cross training between two organizations to enable mutual development and resource sharing.

This paper focuses on skill-specific workforce scheduling in service sector organizations with variable demands. We use flexible work arrangement (FWA) strategies in obtaining minimal workforce combinations to cater service demand. The problem setting is such that the fluctuating service demand requires continuous availability of skill-specific workforce to provide timely service delivery. The solution combines a skill specific workforce-scheduling model with a selected cluster of FWAs to form an algorithm that (i) minimize labour utilization in a service sector organization with variable demand, (ii) compare the effect of individual and combinations of FWAs in improving the objective function (iii) examine the influence of different FWAs and skill combinations towards increased workforce requirement. We formulate the problem as a mixed integer program with an innovative algorithm to solve it in reasonable computational time. We test the model through a case study on a medium scale ...

With the progression of advancements in technology, several innovations has been made in the field of communications that are transiting to Internet of Things. In this domain, Wireless Sensor Networks (WSN) are one of those independent sensing devices to monitor physical and environmental conditions along with thousands of applications in other fields. As air pollution being a major environmental change that causes many hazardous effects on human beings that need to be controlled. Hence, we deployed WSN nodes for constant monitoring of the air pollution around the city and the moving public transport buses and cars. This methodology gave us the monitoring data from the stationary nodes deployed in the city to the mobile nodes on Public Transport buses and cars. The data of the air pollution particles such as gases, smoke and other pollutants is collected via sensors on the Public transport buses and the data is being analyzed when the buses and cars reach back to the source destination after passing through the stationary nodes around the city. Our proposed architecture having innovative mesh network will be more efficient way of gathering data from the nodes of WSN. It will have lots of benefits with respect to the future concept of Smart Cities that will have the new technologies related to Internet of Things.

Name: ________________________________________ ID: ___________________ C) What is the magnetic induction (B) in air 0.0800 m from a long straight wire carrying a current of 14.0 A? Roy forrest D) What is the magnetic field strength (B) in the center of a coil of wire in air with one turn (a loop) with a radius of 0.110 m and a current of 0.420 A? E) What is the magnetic flux density (B) in the center of a solenoid in air with a length 0.140 m and 220 turns when a current of 0.150 A flows through it?

This paper presents an optimising model for integrating the traditional reliabilitv orediction methodolog; with simple analyiical techniques to facilitate-the designer to decide upon the &e*ory faulttolerant choices of an onboard computer. In this exercise. the hardware reliabilitv estimates of a circuit ~ ~ without any error correction as well as that of a circuit with error detection and correction were calculated. The failure rates of each component and soldering have been accounted for inthese orediction orocedures. A suitable probability distribkion is chosen for &ta errors and is analytically combhed with t i e hardware reliability predictions to study the trade-offs. An optimum strategy for introducing the hardware error correction logic in the circuit is presented.

In this paper, the performance of a wireless mesh network (WMN) is improved by introducing a number of long links at strategic locations, based on the small world network concept, to shorten transmission delay. A Genetic Algorithm (GA) is used to determine the minimum number of long links and their locations such that the maximum number of hops of a given WMN with n nodes is minimized. In the optimization process, practical implementation aspects are considered. These include the radio interference likely to be introduced by the long links, and the possibility of traffic congestion at these links. It is envisaged that a long link will be equipped with a higher power transmitter and directional antenna.

In this paper, the performance of a wireless mesh network (WMN) is improved by introducing a number of long links at strategic locations, based on the small world network concept, to shorten transmission delay. A Genetic Algorithm (GA) is used to determine the minimum number of long links and their locations such that the maximum number of hops of a given WMN with n nodes is minimized. In the optimization process, practical implementation aspects are considered. These include the radio interference likely to be introduced by the long links, and the possibility of traffic congestion at these links. It is envisaged that a long link will be equipped with a higher power transmitter and directional antenna.

This paper proposes a method for enhancing the performance of Content Based Image Retrieval, employing a shape feature along with color and texture of Walsh wavelet. The color and texture features of the images are extracted using Walsh Wavelet and the shape feature is extracted by edge detection using any of Roberts, Sobel, Prewitt or Canny Operator. The performance of the approach is tested based on the precision values on a database containing 44 images. The results show that the precision of retrieval is increased when a shape feature is employed in the second stage of a two-stage retrieval process. Adding the shape as a third feature in a single stage retrieval process does not provide any improvement in retrieval performance with respect to precision and recall. Performance comparison was also carried out with other existing approaches, namely Walshlet and Walsh transform. The experimental results show that Walsh Wavelet has higher precision than Walshlet and Walsh transform. Also, shape extraction with Sobel and Prewitt operators provides better performance when compared to Canny and Roberts.

Conventional power steering systems use an engine accessory belt to drive the pump, providing pressurized fluid that operates a piston in the power steering gear or actuator to assist the driver. The aim of steer-by-wire technology is to completely do away with as many mechanical components as possible. Completely replacing conventional steering systems with steer-by-wire holds several advantages. In this paper we propose a steer-by-wire system modified with Field oriented control of motors. This system has two sections-Steering wheel section and Road wheel section. Two motors are used in each section for the torque required in a power steering. The control of these motors to turn the wheels of two sections is the main function of the microcontroller. Controlling methods used for motors are usually sinusoidal method and trapezoidal method but they have certain disadvantages. Therefore we have selected Field Oriented Control (FOC) for motor controlling which provides high efficiency,...

Energy crisis is slowly building up due to the increase in the amount of energy requirement in every field of human existence. Pollution free energy is in great demand due to the government norms implemented worldwide in reducing global warming. Infinite energy from low radiation reactions are currently being explored into. Nuclear Fusion is one of the methods which produces high energy yield with very low radiation effects. This paper explores into the possibility of Low Energy Nuclear Reactions (LENR) [1] which has the potential to curb the ever increasing energy scarcity. Bubble fusion a type of cold fusion, is highlighted in this paper as a major breakthrough in this research field. This paper intends to revive a research in the field of nuclear fusion reactors in the small form factor structure that could be a possible solution for the existing energy crisis.