Abstract: In this study, the Mo-electrode thin films were deposited using two-stepped process and the high purity copper indium selenide-based powder (CuInSe2, CIS) was fabricated by using hydrothermal process by Nanowin Technology Co. Ltd. Because the CIS powder was aggregated into microscale particles, the CIS power was ground into nano-scale particles. 6 wt% CIS particles were mixed and dispersed into isopropyl alcohol (IPA). A new non-vacuum thin-film deposition process, spray coating method (SPM), was investigated to deposit the high-densified CIS absorber layers. 0.1 ml CIS solution was sprayed on the 20 mm×10 mm Mo/glass substrates and then the CuInSe2 thin films were annealed in a selenization furnace using N2 as atmosphere. The annealing temperature and time were set at 550oC and 5 min, and 0.0g~0.6g extra Se content was added in the furnace. The influences of extra Se content on the densification, crystallization, resistivity (ρ), hall mobility (μ), and carrier concentration of the CIS absorber layers were well investigated in this study.
Abstract: In this study, we investigated (In,Ga,Zn)Ox (IGZO) thin films and examined their characteristics of using Ga2O3-2 ZnO (GZO) co-sputtered In2O3 prepared by dual target radio frequency magnetron sputtering at room temperature in a pure Ar atmosphere. RF powers of 80 W and 70 W were used for GZO and pure In2O3, room temperature (RT) was used as deposition temperature, and the deposition time was changed from 15 min to 60 min. Structural, surface, electrical, and optical properties of IGZO thin films were investigated as a function of deposition time. Furthermore, the GZO co-sputtered In2O3 thin films showed a very smooth and featureless surface and an amorphous structure regardless of the deposition time due to the room temperature sputtering process. We would show that the co-sputtered IGZO thin films exhibited transparent electrode properties with high transmittance ratio and low resistivity.
Abstract: To avoid battery assisted tags with limited lifetime batteries, it is proposed here to replace them by energy harvesting
systems, able to feed from local environment. This would allow total
independence to RFID systems, very interesting for applications
where tag removal from its location is not possible. Example is here
described for luggage safety in airports, and is easily extendable to similar situation in terms of operation constraints. The idea is to fix
RFID tag with energy harvesting system not only to identify luggage
but also to supply an embedded microcontroller with a sensor
delivering luggage weight making it impossible to add or to remove
anything from the luggage during transit phases. The aim is to
optimize the harvested energy for such RFID applications, and to
study in which limits these applications are theoretically possible.
Proposed energy harvester is based on two energy sources:
piezoelectricity and electromagnetic waves, so that when the luggage
is moving on ground transportation to airline counters, the piezo
module supplies the tag and its microcontroller, while the RF module
operates during luggage transit thanks to readers located along the
way. Tag location on the luggage is analyzed to get best vibrations, as
well as harvester better choice for optimizing the energy supply
depending on applications and the amount of energy harvested during
a period of time. Effects of system parameters (RFID UHF
frequencies, limit distance between the tag and the antenna necessary
to harvest energy, produced voltage and voltage threshold) are
discussed and working conditions for such system are delimited.
Abstract: The reported study focuses on pre-service teachers’ professional development during the teaching practice. The cohort studied comprised participants in their final year in the Bachelor of Arts and Bachelor of Science with Graduate Certificate in Education programmes of a university in Fiji. Analysis of the data obtained using a survey questionnaire indicates that overall, the pre-service teachers were satisfied with the practicum experience. This is assumed to demonstrate that the practicum experience contributed well towards their professional preparation for work expected of them in Fiji secondary schools. Participants also identified some concerns as needing attention. To conclude, the paper provides suggestions for improving the preparation of teachers by strengthening the identified areas of the practicum offered by the university. The study has implications for other teacher education providers in small developing island states and even beyond for the purpose of enhancing learning in student teachers’ for future work.
Abstract: Using the technology acceptance model (TAM), this
study examined the external variables of technological complexity
(TC) to acquire a better understanding of the factors that influence the
acceptance of computer application courses by learners at Active
Aging Universities. After the learners in this study had completed a
27-hour Facebook course, 44 learners responded to a modified TAM
survey. Data were collected to examine the path relationships among
the variables that influence the acceptance of Facebook-mediated
community learning. The partial least squares (PLS) method was used
to test the measurement and the structural model. The study results
demonstrated that attitudes toward Facebook use directly influence
behavioral intentions (BI) with respect to Facebook use, evincing a
high prediction rate of 58.3%. In addition to the perceived usefulness
(PU) and perceived ease of use (PEOU) measures that are proposed in
the TAM, other external variables, such as TC, also indirectly
influence BI. These four variables can explain 88% of the variance in
BI and demonstrate a high level of predictive ability. Finally,
limitations of this investigation and implications for further research
are discussed.
Abstract: Micro-reading is a new way of reading depended on short messages of mobile phones, network articles and short literary forms, which impacts greatly on traditional way of reading. The effect of "micro-reading" is deeper especially for those growing middle school students and college students. Aiming at the problem with the development of college students' micro-reading and based on the influence of schema theory on the research of cognition of reading, this paper is to analyze the comparison between micro-reading and traditional reading and explore reading strategies in micro-era based on the negative and positive effect which schema theory has on micro-reading.
Abstract: This paper proposes a new method to find the equations
of transformation matrix for the rotation angles of the two rotational
axes and the coordinates of the three linear axes of an orthogonal
multi-axis milling machine. This approach provides intuitive physical
meanings for rotation angles of multi-axis machines, which can be
used to evaluate the accuracy of the conversion from CL data to NC
data.
Abstract: In this paper, a sliding mode control method based on the passivity approach is proposed to control the position of surface-mounted permanent magnet synchronous motors (PMSMs). Firstly, the dynamics of a PMSM was proved to be strictly passive. The position controller with an adaptive law was used to estimate the load torque to eliminate the chattering effects associated with the conventional sliding mode controller. The stability analysis of the overall position control system was carried out by adopting the passivity theorem instead of Lyapunov-type arguments. Finally, experimental results were provided to show that the good position tracking can be obtained, and exhibit robustness in the variations of the motor parameters and load torque disturbances.
Abstract: The objectives of this research were to develop and find the efficiency of integrated online lessons by investigating the usage of online lessons, the relationship between learners’ background knowledge, and the achievement after learning with online lessons. The sample group in this study consisted of 97 students randomly selected from 121 students registering in 1/2012 at Trimitwittayaram Learning Center. The sample technique employed stratified sample technique of 4 groups according to their proficiency, i.e. high, moderate, low, and non-knowledge. The research instrument included online lessons in integration model on the topic of Java Programming, test after each lesson, the achievement test at the end of the course, and the questionnaires to find learners’ satisfaction. The results showed that the efficiency of online lessons was 90.20/89.18 with the achievement of after learning with the lessons higher than that before the lessons at the statistically significant level of 0.05. Moreover, the background knowledge of the learners on the programming showed the positive relationship with the achievement learning at the statistically significant level at 0.05. Learners with high background knowledge employed less exercises and samples than those with lower background knowledge. While learners with different background in the group of moderate and low did not show the significant difference in employing samples and exercises.
Abstract: Historically, actuators’ redundancy was used to deal
with faults occurring suddenly in flight systems. This technique was
generally expensive, time consuming and involves increased weight
and space in the system. Therefore, nowadays, the on-line fault
diagnosis of actuators and accommodation plays a major role in the
design of avionic systems. These approaches, known as Fault
Tolerant Flight Control systems (FTFCs) are able to adapt to such
sudden faults while keeping avionics systems lighter and less
expensive. In this paper, a (FTFC) system based on the Geometric
Approach and a Reconfigurable Flight Control (RFC) are presented.
The Geometric approach is used for cosmic ray fault reconstruction,
while Sliding Mode Control (SMC) based on Lyapunov stability
theory is designed for the reconfiguration of the controller in order to
compensate the fault effect. Matlab®/Simulink® simulations are
performed to illustrate the effectiveness and robustness of the
proposed flight control system against actuators’ faulty signal caused
by cosmic rays. The results demonstrate the successful real-time
implementation of the proposed FTFC system on a non-linear 6 DOF
aircraft model.
Abstract: In this paper, Backstepping method is proposed to synchronize two fractional-order systems. The simulation results show that this method can effectively synchronize two chaotic systems.
Abstract: This paper presents the gain improvement of a sector antenna for mobile phone base station by using the new technique to enhance its gain for microstrip antenna (MSA) array without construction enlargement. The curved woodpile Electromagnetic Band Gap (EBG) has been utilized to improve the gain instead. The advantages of this proposed antenna are reducing the length of MSAs array but providing the higher gain and easy fabrication and installation. Moreover, it provides a fan-shaped radiation pattern, wide in the horizontal direction and relatively narrow in the vertical direction, which appropriate for mobile phone base station. The paper also presents the design procedures of a 1x8 MSAs array associated with U-shaped reflector for decreasing their back and side lobes. The fabricated curved woodpile EBG exhibits bandgap characteristics at 2.1 GHz and is utilized for realizing a resonant cavity of MSAs array. This idea has been verified by both the Computer Simulation Technology (CST) software and experimental results. As the results, the fabricated proposed antenna achieves a high gain of 20.3 dB and the half-power beam widths in the E- and H-plane of 36.8 and 8.7 degrees, respectively. Good qualitative agreement between measured and simulated results of the proposed antenna was obtained.
Abstract: The conventional rectangular horn has been used for microwave antenna a long time. Its gain can be increased by enlarging the construction of horn to flare exponentially. This paper presents a study of the shaped woodpile Electromagnetic Band Gap (EBG) to improve its gain for conventional horn without construction enlargement. The gain enhancement synthesis method for shaped woodpile EBG that has to transfer the electromagnetic fields from aperture of a horn antenna through woodpile EBG is presented by using the variety of shaped woodpile EBGs such as planar, triangular, quadratic, circular, gaussian, cosine, and squared cosine structures. The proposed technique has the advantages of low profile, low cost for fabrication and light weight. The antenna characteristics such as reflection coefficient (S11), radiation patterns and gain are simulated by utilized A Computer Simulation Technology (CST) software. With the proposed concept, an antenna prototype was fabricated and experimented. The S11 and radiation patterns obtained from measurements show a good impedance matching and a gain enhancement of the proposed antenna. The gain at dominant frequency of 10 GHz is 25.6 dB, application for X- and Ku-Band Radar, that higher than the gain of the basic rectangular horn antenna around 8 dB with adding only one appropriated EBG structures.
Abstract: This paper proposes the development and design of
double layer metamaterials based on electromagnetic band gap
(EBG) rods as a superstrate of a resonator antenna to enhance
required antenna characteristics for the mobile base station. The
metallic rod type metamaterial can partially reflect wave of a primary
radiator. The antenna was designed and analyzed by a simulation
result from CST Microwave Studio and designed technique could be
confirmed by a measurement results from prototype antenna that
agree with simulation results. The results indicate that the antenna
can also generate a dual polarization by using a 45˚ oriented curved
strip dipole located at the center of the reflector plane with double
layer superstrate. It can be used to simplify the feed system of an
antenna. The proposed antenna has a bandwidth covering the
frequency range of 1920 – 2200 MHz, the gain of the antenna
increases up to 14.06 dBi. In addition, an interesting sectoral 60˚
pattern is presented in horizontal plane.
Abstract: The paper presents actual benefits and drawbacks of a multidirectional autonomous hovercraft conceived with limited resources and designed for indoor exploration. Recent developments in the field have led to the apparition of very powerful automotive systems capable of very high calculation and exploration in complex unknown environments. They usually propose very complex algorithms, high precision/cost sensors and sometimes have heavy calculation consumption with complex data fusion. These systems are usually powerful but have a certain price, and the benefits may not be worth the cost, especially considering their hardware limitations and their power consumption. The present approach is to build a compromise between cost, power consumption and results preciseness.
Abstract: By running transactions under the SNAPSHOT isolation
we can achieve a good level of concurrency, specially in databases
with high-intensive read workloads. However, SNAPSHOT is not
immune to all the problems that arise from competing transactions
and therefore no serialization warranty exists. We propose in this
paper a technique to obtain data consistency with SNAPSHOT by using
some special triggers that we named DAEMON TRIGGERS. Besides
keeping the benefits of the SNAPSHOT isolation, the technique is
specially useful for those database systems that do not have an
isolation level that ensures serializability, like Firebird and Oracle. We
describe all the anomalies that might arise when using the SNAPSHOT
isolation and show how to preclude them with DAEMON TRIGGERS.
Based on the methodology presented here, it is also proposed the
creation of a new isolation level: DAEMON SNAPSHOT.
Abstract: In a perfect secret-sharing scheme, a dealer distributes
a secret among a set of participants in such a way that only qualified
subsets of participants can recover the secret and the joint share of the
participants in any unqualified subset is statistically independent of
the secret. The access structure of the scheme refers to the collection
of all qualified subsets. In a graph-based access structures, each vertex
of a graph G represents a participant and each edge of G represents a
minimal qualified subset. The average information ratio of a perfect
secret-sharing scheme realizing a given access structure is the ratio
of the average length of the shares given to the participants to the
length of the secret. The infimum of the average information ratio
of all possible perfect secret-sharing schemes realizing an access
structure is called the optimal average information ratio of that access
structure. We study the optimal average information ratio of the
access structures based on bipartite graphs. Based on some previous
results, we give a bound on the optimal average information ratio
for all bipartite graphs of girth at least six. This bound is the best
possible for some classes of bipartite graphs using our approach.
Abstract: Cloud outsource storage is one of important services in cloud computing. Cloud users upload data to cloud servers to reduce the cost of managing data and maintaining hardware and software. To ensure data confidentiality, users can encrypt their files before uploading them to a cloud system. However, retrieving the target file from the encrypted files exactly is difficult for cloud server. This study proposes a protocol for performing multikeyword searches for encrypted cloud data by applying k-nearest neighbor technology. The protocol ranks the relevance scores of encrypted files and keywords, and prevents cloud servers from learning search keywords submitted by a cloud user. To reduce the costs of file transfer communication, the cloud server returns encrypted files in order of relevance. Moreover, when a cloud user inputs an incorrect keyword and the number of wrong alphabet does not exceed a given threshold; the user still can retrieve the target files from cloud server. In addition, the proposed scheme satisfies security requirements for outsourced data storage.
Abstract: This study examined the predictive effects of moral competence, prosocial norms and positive behavior recognition on school misbehavior among Chinese junior secondary school students. Results of multiple regression analysis showed that students were more likely to misbehave in school when they had lower levels of moral competence and prosocial norms, and when they perceived their positive behavior being less likely recognized. Practical implications were discussed on how to guide students to make the right choices to behave appropriately in school. Implications for future research were also discussed.
Abstract: The aim of this research is to evaluate the effectiveness of software quality assurance approaches of Sri Lankan offshore software development organizations, and to propose a framework which could be used across all offshore software development organizations.
An empirical study was conducted using derived framework from popular software quality evaluation models. The research instrument employed was a questionnaire survey among thirty seven Sri Lankan registered offshore software development organizations.
The findings demonstrate a positive view of Effectiveness of Software Quality Assurance – the stronger predictors of Stability, Installability, Correctness, Testability and Changeability. The present study’s recommendations indicate a need for much emphasis on software quality assurance for the Sri Lankan offshore software development organizations.