Perkembangan motor kasar murid tahun satu sekolah rendah

Pentingnya kanak-kanak mempunyai perkembangan motor yang baik kerana ianya mempengaruhi kanak�kanak lain dalam perkembangan motor secara menyeluruh dan bersepadu. Dengan menilai tahap perkembangan motor murid sekolah rendah, guru boleh melakukan intervensi bagi meningkatkan tahap perkembangan motor serta pada masa yang sama, memastikan murid ini mengalami perkembangan yang holistik. Tujuan kajian ini adalah untuk mengenal pasti tahap perkembangan motor kasar murid-murid tahun satu dan menilai perkembangan murid setelah setahun. Seramai 105 orang murid tahun satu yang terdiri daripada 46 lelaki dan 59 perempuan dalam kalangan murid sekolah rendah di Johor adalah responden untuk kajian ini. Tahap perkembangan motor kasar diukur dengan menggunakan Test of Gross Motor Development Second Edition (TGMD – 2). Dapatan kajian menunjukkan bahawa pada keseluruhan, tahap perkembangan motor kasar adalah bawah sederhana (M=84.11 min, S=9.99) pada awal tahun dan tidak mempunyai perbezaan yang singnifikan pada akhir tahun (M=85.91=6.77). Kemahiran lokomotor didapati meningkat pada akhir tahun, tetapi kemahiran kawalan objek tidak mempunyai perbezaan yang signifikan. Dapatan kajian ini menunjukkan kanak-kanak di Malaysia kurang didedahkan kepada permainan yang menggunakan objek. Dengan itu guru Pendidikan Jasmani perlu memberikan pendekatan tersebut disekolah

Development of Reduced Complexity Models for Electromagnetic Modeling

The current and field distributions of various structures can be calculated using full-wave numerical modeling codes. However, this approach is limited by the complex models and extensive computational resources required to analyze the details of each structure. In addition, brute-force modeling of the entire geometry provides relatively little physical insight into the electromagnetic interference (EMI) source mechanisms. Alternatively an effective equivalent model can be obtained by eliminating sources and structures that do not contribute significantly to the radiated emissions and focusing on the features that could possibly be significant sources of EMI. Equivalent models are generally much simpler than model-everything full-wave models and provide physical insight into the features that have the greatest impact on radiated emissions. This dissertation includes four chapters on development of reduced complexity models for the modeling of antennas and printed circuit board (PCB) structures. In the first chapter, a simplified model for normal mode helical antennas is proposed. In this model, the highly curved structure of the helix is replaced with straight wires and lumped elements. The simplified model can be used to reduce the complexity of full-wave models that include a helical antenna. It also can be used to estimate the performance of a helical antenna without full-wave modeling of the helical structure. The second chapter describes a model for determining the common-mode currents on cables attached to a PCB that is based on the concept of imbalance difference. The imbalance difference model is derived from research that shows that changes in geometrical imbalance cause differential- to common-mode conversion. The imbalance difference model can be used to estimate the radiated emissions from trace-board structures due to common-mode currents induced on attached cables. The third chapter introduces a new closed-form expression for estimating the maximum radiated emissions from the board-source-cable structure. This expression is based on two improvements to a closed-form expression in a 2008 paper published in the IEEE Transactions on EMC. The accuracy of the estimate for larger frequency ranges is improved by using an expression for the envelope of F(è, k, lant) that equals the maximum value at every resonant frequency. A modified expression for calculating the effective length of the board improves the accuracy of the estimate when applied to nearly square boards. In the forth chapter, a modeling technique is proposed to speed up the analysis of PCBs with coupled microstrip lines that induce common-mode currents on attached cables. Based on the concept of imbalance difference, differential-mode sources are converted to equivalent common-mode sources that drive the attached cable and the PCB reference plane. A closed-form expression is also developed based on the imbalance difference model to estimate the maximum radiated emissions from the PCB

Electromagnetic Compatibility Research in Wire Harnesses and CAN Transceivers

This dissertation develops methods how to design wire harnesses reducing common mode components and to analyze the conversion from differential mode to common mode. The three chapters presented are design methods how to figure out the impact of the common-mode components, not only describe the test results but provide important insight as to how the design related to radiated emissions. In the first chapter of this dissertation, the method designing wire harnesses has been presented to match the electrical balance of the circuit board (PCB). This is accomplished via calculating the current division factor (CDF) of the wire harnesses and the PCB, which provides us with the electrical balance of a transmission line. To reduce the amount of common-mode currents induced on the harness, matching the imbalance of the wire harness to the imbalance of its source and termination is essential. The second chapter explores Controller Area Network (CAN) characteristics. Unintentional common-mode components of the CAN transceivers are analyzed and evaluated to determine how much common-mode voltage they produce in various circumstances. The final chapter provide valuable understanding such that ground proximity impacts on the common-mode currents of wire harnesses. The electrical balance change of the wire harness depending on the distance from ground structures is highlighted. It is also analyzed that losing the ground wire impacts on the common-mode excitation

People, process and system design of smart office solution

In a smart building, physical and computational elements such as people, processes and systems are integrated to create an environment that is safe, energy-efficient, comfortable for its occupants. Due to 4th Industrial Revolution (IR 4.0), many organizations are taking initiatives to practice and develop smarter solutions to reduce operation cost using building automations and innovations that also brings values to human productivity. The issue of maintenance and management of office building needed to be study to establish the good proposal of smart building solutions. This research was first determined the people and their responsibilities involving in the building operation of an office building through first phase of purposive sampling interviews. Multiple second phase of process as-is workshop interviews were carried out with building management team and related departments to identify the challenges and issues on maintenance and management issue in office building and their aspiration of modern energy-efficient building. Accordingly, there were 30 respondents from the organization participated in these workshop interviews, 23 type of building operation related processes and 4 main categories of related systems were studied in this research. The office building consisting of a mix of digitalised and manual processes, due to the lack of integration between the different systems employed, it was further complicated by the lack of coordination between the separate departments who work with separate system. These data were then analysed by 8 building experts to introduce a set of proposed smart building solutions for improving the building operation management, promote energy-saving in building system and enhance productivity of occupants. Moreover, the benefits of this research are that the proposed building management solutions can be applied to a variety of smart buildings by considering the building’s physical models, environmental conditions, comfort specifications, occupants’ preferences and safety in the design

Maximum Radiated Emissions of Printed Circuit Board Using Analytical Methods

The rapid progress of technology has imposed significant challenges on Printed Circuit Boards (PCB) designers. Once of those challenges is to satisfy the electromagnetic compatibility (EMC) compliance requirements. For that reason, EMC compliance must be considered earlier at the design stage for time and cost savings. Conventionally, full wave simulation is employed to check whether the designed PCB meets EMC standards or not. However, this method is not a suitable option since it requires intensive computational time and thus increasing the unit cost. This paper describes novel analytical models for estimating the radiated emissions (RE) of PCB. These models can be used to help the circuit designer to modify their circuit based on the maximum allowable RE comparing to the relevant EMC-RE standard limit. Although there are many RE sources on PCB, this paper focuses on the significant source of RE on PCB; namely PCB-traces. The trace geometry, termination impedance, dielectric type, etc. can be specified based on the maximum allowable emissions. The proposed models were verified by comparing the results of the proposed models with both simulation and experimental results. Good agreements were obtained between the analytically computed results and simulation/measurement results with accuracy of ±3dB

EMC in Power Electronics and PCB Design

This dissertation consists of two parts. Part I is about Electromagnetic Compatibility (EMC) in power electronics and part II is about the Maximum Radiated Electromagnetic Emissions Calculator (MREMC), which is a software tool for EMC in printed circuit board (PCB) design. Switched-mode power converters can be significant sources of electromagnetic fields that interfere with the proper operation of nearby circuits or distant radio receivers. Part I of this dissertation provides comprehensive and organized information on the latest EMC developments in power converters. It describes and evaluates different technologies to ensure that power converters meet electromagnetic compatibility requirements. Chapters 2 and 3 describe EMC noise sources and coupling mechanisms in power converters. Chapter 4 reviews the measurements used to characterize and troubleshoot EMC problems. Chapters 5 - 8 cover passive filter solutions, active filter solutions, noise cancellation methods and reduced-noise driving schemes. Part II describes the methods used, calculations made, and implementation details of the MREMC, which is a software tool that allows the user to calculate the maximum possible radiated emissions that could occur due to specific source geometries on a PCB. Chapters 9 - 13 covers the I/O coupling EMI algorithm, Common-mode EMI algorithm, Power Bus EMI algorithm and Differential-Mode EMI algorithm used in the MREMC

INVESTIGATION OF TECHNIQUES FOR REDUCING UNINTENTIONAL ELECTROMAGNETIC EMISSIONS FROM ELECTRONIC CIRCUITS AND SYSTEMS

This dissertation describes three independent studies related to techniques for reducing unintentional electromagnetic emissions from electronic circuits and systems. The topics covered are: low-inductance multi-layer ceramic capacitor for high frequency circuit board decoupling, the application of imbalance difference model to various circuit board and cable geometries, and balanced cable interface for reducing common-mode currents from power inverter. The first chapter discusses the importance and the meaning of the connection inductance associated with MLCCs and analyzes the effect of plate orientation in MLCCs. It demonstrates that vertically oriented plates have no more or less inductance than horizontally oriented plates when the overall dimensions of the plate stack are similar. Decoupling capacitance options at the various levels of a high-speed circuit is investigated to determine the range of frequencies that decoupling at each level is likely to be is effective. Innovative low-inductance capacitive-stem capacitor configurations are described and their connection impedance is compared to that of standard surface-mounted capacitors. The second chapter investigates the imbalance difference model that is a method for modeling how differential-mode signal currents are converted to common-mode noise currents. Various cable geometries to determine how well imbalance factor`s values of DM-to-CM conversion compare to full-wave calculations are explored. The imbalance difference model can be applied to cables with more than two conductors are demonstrated. The third chapter investigates the balanced cable interface for reducing common-mode currents from power inverter. The concept of a balancing network to reduce the common-mode currents on power inverter cables above 30 MHz is introduced. An experimental test set-up is used to demonstrate the effect of a balancing network on the common-mode current, differential-mode current and the common-mode rejection ratio on a balanced cable with an imbalanced termination. The balancing network is also evaluated using a 3-phase brushless DC motor driver to verify its effectiveness in a real application

Maximum crosstalk estimation and modeling of electromagnetic radiation from PCB/high-density connector interfaces

This dissertation explores two topics pertinent to electromagnetic compatibility research: maximum crosstalk estimation in weakly coupled transmission lines and modeling of electromagnetic radiation resulting from printed circuit board/high-density connector interfaces. Despite an ample supply of literature devoted to the study of crosstalk, little research has been performed to formulate maximum crosstalk estimates when signal lines are electrically long. Paper one illustrates a new maximum crosstalk estimate that is based on a mathematically rigorous, integral formulation, where the transmission lines can be lossy and in an inhomogeneous media. Paper two provides a thorough comparison and analysis of the newly derived maximum crosstalk estimates with an estimate derived by another author. In paper two the newly derived estimates in paper one are shown to be more robust because they can estimate the maximum crosstalk with fewer and less restrictive assumptions. One current industry challenge is the lack of robust printed circuit board connector models and methods to quantify radiation from these connectors. To address this challenge, a method is presented in paper three to quantify electromagnetic radiation using network parameters and power conservation, assuming the only losses at a printed circuit board/connector interface are due to radiation. Some of the radiating structures are identified and the radiation physics explored for the studied connector in paper three. Paper four expands upon the radiation modeling concepts in paper three by extending radiation characterization when material losses and multiple signals may be present at the printed circuit board/connector interface. The resulting radiated power characterization method enables robust deterministic and statistical analyses of the radiated power from printed circuit board connectors. Paper five shows the development of a statistical radiated power estimate based on the radiation characterization method presented in paper four. Maximum radiated power estimates are shown using the Markov and Chebyshev inequalities to predict a radiated power limit. A few maximum radiated power limits are proposed that depend on the amount of known information about the radiation characteristics of a printed circuit board connector --Abstract, page iv

Source reconstruction in near field scanning for RFI application

This research is divided into three major topics. The first topic, mechanical magnetic field generator for communication in the ULF range, is discussed in the first paper. The second topic, source reconstruction in near field scanning for RFI application, is discussed over the course of two papers. The third topic, analysis of imbalanced 2 or 3 Wire VHF LISN, is discussed in the last two papers. In the first topic, the possibility to use a mechanical system (a rotating magnet) as a source (generator or antenna combined) of the ULF magnetic field is investigated. Ultralow frequency (ULF) communication systems have advantage over the RF systems in lossy media such as soil or water. A conventional way to create ULF fields is to use coils. It is demonstrated that the mechanical sources have advantage over coils in terms of occupied volume or dissipated power and can be a viable alternative for low-size, weight, and power applications. In the second topic, methods are presented to predict the high-frequency near electric- and magnetic- fields from a component using a Method of Moment (MoM) approach. Additionally, the impact of three major sources of error in near field scans: random measurement noise, cross field coupling, and position error, is investigated on field prediction. A clear decision-making process with examples is provided to guide the user toward selection of the best representation. In the third topic, an analysis of an imbalanced two- or three-wire VHF LISN is conducted in terms of its mode conversion and termination impedance. It is demonstrated that an imbalanced termination impedance provides a specified degree of conversion from differential- to common-mode, which can lead to more representative radiated emission test results --Abstract, page iv