Nasrul Hadi Johari

Comparative analysis of realistic CT-scan and simplified human airway models in airflow simulation

Efforts to model the human upper respiratory system have undergone many phases. Geometrical proximity to the realistic shape has been the subject of many research projects. In this study, three different geometries of the trachea and main bronchus were modelled, which were reconstructed from computed tomography (CT) scan images. The geometrical variations were named realistic, simplified and oversimplified. Realistic refers to the lifelike image taken from digital imaging and communications in medicine format CT scan images, simplified refers to the reconstructed image based on natural images without realistic details pertaining to the rough surfaces, and oversimplified describes the straight wall geometry of the airway. The characteristics of steady state flows with different flow rates were investigated, simulating three varied physical activities and passing through each model. The results agree with previous studies where simplified models are sufficient for providing comparable results for airflow in human airways. This work further suggests that, under most exercise conditions, the idealised oversimplified model is not favourable for simulating either airflow regimes or airflow with particle depositions. However, in terms of immediate analysis for the prediction of abnormalities of various dimensions of human airways, the oversimplified techniques may be used.

THE EFFECT OF DIFFERENT LOCATIONS OF TRACHEAL STENOSIS TO THE FLOW CHARACTERISTICS USING RECONSTRUCTED CT-SCANNED IMAGE

The presence of tracheal stenosis would alter the flow path of the inhaled and exhaled air and subsequently changed the flow behavior inside the trachea and main bronchi. Therefore, it was our aim to investigate and predict the changes of flow behavior along with the pressure distribution with respect to the presence of stenosis on the tracheal lumen. In this study, actual CT scan images were extracted for flow modeling purposes. The images were then reconstructed to mimic the effect of different stenosis locations. This method overcomes the problem of the absence of actual images for different tracheal stenosis locations. The flow was subjected to different breathing situations corresponding to low, moderate and rigorous activities. The results showed that for flow over the stenosis farthest from the bifurcation, the pressure drop was insignificant for all breathing situations. At the same time, the inlet flow rate at the bifurcation showed less air flows into the right lung as compared to healthy flow conditions. On the other hand, for the flow over stenosis closest to the bifurcation, the pressure drop near the bifurcation area was very significant at high flow rate.

Comparison of simplified and actual model of trachea and main bronchi in airflow simulation

Understanding of airflow in human airways is beneficial to medical field. Through the understanding, assessment on severity of airway disease and efficiency of medical inhalation drugs delivery can be assessed. For this purpose, an accurate and realistic human lung model is needed. With the variability in the outcomes based on both models notified, the reliability of the simplified models is questionable. It is the aim of this paper to determine the accuracy of the simplified models against actual human airways. Two models of trachea and main bronchi with different conditions; actual model and simplified were developed for comparison purpose. Different conditions of inspiratory breathing, 5 l/min, 9 l/min, 12 l/min and 15 l/min were imposed at the outlet with different ratio, 55% for right bronchus and another 45% for left. The results showed that the simplified model is reliable to provide accurate result on airflow in the airways. However, the level of accuracy diminished in regions with complex geometry i.e. highly irregular cross-sectional shape, rapid change in cross-sectional area, and around small radius curvature.

Numbering with spiral pattern to prove authenticity and integrity in medical images

With the rapid development of technology in digital multimedia, manipulation and misconduct of digital data are soaring. The watermarking procedure is seen as helpful to protect the security of digital images which are highly confidential such as medical images. In this study, an efficient watermarking method for greyscale images is proposed. The scheme is designed to achieve good numbering pattern, exact detection and image recovery. The proposed scheme uses a unique spiral pattern numbering before implementing the block-based mechanism for embedding. The experiment tests the difference between using normal pattern and unique spiral pattern in numbering, and the results show that the proposed method produces a great quality value of embedded image with great tamper localization and recovery ability. This function can help in proving authenticity and integrity of medical images in the system.

Simulation of stenosis effect on airflow pattern in trachea and main bronchi

Tracheal stenosis is a condition where the diameter size of trachea wall decreases and leads to the obstruction of the breathing airflow. Investigation on the effect of the stenosis to the airflow pattern in the trachea and main bronchi is the objective for this study. CT-scan images of two airways models were modeled, one with the stenosis and one without. Numerical solution was used to study the airway pattern inside the airway. Different boundary conditions of inspirations flow rate were applied; 15 l/min, 60 l/min and 100l/min where the ratio for the right main bronchus is 55% and for the left main bronchus is 45%. The results showed that the pressure drop inside the stenosis model is higher compared to that of healthy model. The pressure drop was also shown to interrupt the inlet condition into the main bronchi.

The effect of mild stenosis to flow in Trachea

Flow in the trachea is essential to be properly understood since it is the inlet to the lungs. Disturbance to this flow will disrupt the inlet conditions to both bronchi. In this study, disturbance of flow due to mild stenosis is investigated via numerical models. The effect of various stenosis sizes, at the middle of the trachea, to the flow pattern is studied and analyzed. 3D simplified trachea models were used and different flow conditions were applied. The results show two stages of pressure drop behavior appear as the size of the stenosis reaches fifty percent of the airway size. The inlet condition to the bronchi is also significantly disturbed as the stenosis reaches fifty percent.

Analysis of an Olympic Scale of a Recurve Bow Riser on the Basis of Malaysian Under 15 and Under 17 Archers

Recurve bow is the only type of bow that used in Olympic Games. To date, none of this bow that suits to Malaysian junior archers. This paper aims to analyze a recurve bow riser on the basis of Malaysian anthropometry. Anthropometric data of Malaysian population was gathered to analyze the loads during drawn bow. A static structural analysis of the Matrix riser was executed on a final design of recurve bow riser. The finding from this study shows that the maximum displacement of recurve riser is correspondence to the established previous study. It can be concluded that the design of recurve bow riser can sustain the force applied by Malaysian junior athletes when they aim the target board at a full drawn bow position. The developed bow riser can be very beneficial for both athletes and coaches during training.

A Comparison of Muscular Activity among European, Korea and Malaysian During Seating Using Musculoskeletal Computational Analysis Method

Sitting is the most common posture in any industry field either in office work, manufacturing or even automotive. Sit for a long time lead to musculoskeletal disorder which causes muscle fatigue. However, different size of people will have a different level of muscle activation. The objective of this paper is to analyse and compare the muscle activation during sitting among European, Korean, and Malaysian. The human size employed for this study is by 95th percentile male. The AnyBody Modelling Software is used to simulate and analyse the human muscle activity of the seating posture of these respective countries. Our finding showed that the trunk of the human body has the highest muscle activity. The Malaysian anthropometry showed the highest muscle activity in sitting posture; followed by Korean and European.

The kicking performance by different boots material

The purpose of this study was to investigate the kinematics of kicking by experimental and simulation techniques analysis. The differences of material stiffness will affected to the ball velocities. Experimental setup by high speed video camera with 250 frames per second was performed in order to obtain the foot and ball velocities during the kicking process. There are 10 male football players from Majlis Sukan Negeri Terengganu (MSNT) were selected as subjects. Instep kicking with right foot was choosing due to the highest ball velocities can be produced by this technique. Simulation analysis by finite element analysis (FEA) then used to validate the results from experimental work done. Polyethylene material and 2.0mm thickness from boot C was considered as the best boot design compared to the others. It gives the highest maximum stress and the highest force to produce the highest ball velocity. The other variables related to the ball velocity such as coefficient of restitution (COR) and contact time. This study is useful to design the suitable material for each region of boots. It also can help the athletes to identify the characteristics of boot selection for different position on the field.

Authentication system for medical images using Hilbert numbering

Medical image is seen as one of crucial data that demand for authentication method as it is highly confidential and used in insurance claim, evidence of jurisdiction and personal identification. Nowadays, Hospital Information System (HIS) is used widely at hospitals and clinical departments and it handles thousands of crucial electronic data in medical. We have introduced a fragile watermarking method using spiral manner numbering which showed a good numbering system and excellent embedding, but due to the technique, it only embedded in square shape. We enhanced the scheme to the Hilbert numbering scheme, which is more compatible with medical image modalities, which is not only specific to square shape of image but applicable to all kinds of image.