Mushtak Al-Atabi

Experimental investigation of a single cylinder diesel engine as a hybrid power unit for a series hybrid electric vehicle

Performance and emission testing, for a single cylinder, four-stroke diesel engine, have been experimentally performed to determine the optimum operation conditions for this engine when used as a hybrid power unit (HPU). The studied operation parameters included; Brake Specific Fuel Consumption (BSFC), exhaust emission (NO/sub x/, CO, CO/sub 2/ and O/sub 2/) and engine life. The results indicate that the lowest BSFC of the engine is found when the engine runs around 1 kW charging load when the engine speed ranged between 1900 rpm-2700 rpm. As the speed of the engine is maintained constant, the minimum level of BSFC is below 300 g/kW.hr at around 1900 rpm. The engine best operation conditions, for low emission, are found at engine speed around 2500 rpm. It was found that the oxides of nitrogen remain within the acceptable level (below 180 ppm) for such a diesel engine.

Experimental Investigation of the Use of Synthetic Jets for Mixing in Vessels

Mixing is an important process in various industries. Different designs have been suggested in order to reduce the local shear rates in mechanically stirred mixing vessels, also known as continuously stirred tank reactors, in order to account for the mixing requirements for sensitive materials such as biological materials and biofluids where the high shear rate may damage the sensitive materials. This paper reports on the development of a continuously stirred tank reactor that can be used to achieve a variety of mixing assignments. This mixing is achieved using synthetic jets. The mixing performance was assessed using flow visualization techniques. The effects of fluid viscosity on mixing time were investigated. The results are very encouraging and are suggestive that the use of synthetic jets in mixing is a viable alternative to the conventional methods of mixing in vessels.

Acoustic Absorption of Natural Fiber Composites

The current study is a bibliographic observation on prevailing tendencies in the development of acoustic absorption by natural fiber composites. Despite having less detrimental environmental effects and thorough availability, natural fibers are still unsuitable for wide implementation in industrial purposes. Some shortcomings such as the presence of moisture contents, thicker diameter, and lower antifungus quality hold up the progress of natural fiber composites in staying competitive with synthetic composites. The review indicates the importance of the pretreatment of fresh natural fiber to overcome these shortcomings. However, the pretreatment of natural fiber causes the removal of moisture contents which results in the decrease of its acoustic absorption performance. Incorporation of granular materials in treated fiber composite is expected to play a significant role as a replacement for moisture contents. This review aims to investigate the acoustic absorption behavior of natural fiber composites due to the incorporation of granular materials. It is intended that this review will provide an overview of the analytical approaches for the modeling of acoustic wave propagation through the natural fiber composites. The possible influential factors of fibers and grains were described in this study for the enhancement of low frequency acoustic absorption of the composites.

Biomechanical assessment of surgical repair of the mitral valve.

Repair of the mitral valve is defined (loosely) as a procedure that alters the valve structure, without replacement, enabling the natural valve itself to continue to perform under the physical conditions to which it is exposed. As the mitral valve is driven by flow and pressure, it should be feasible to analyse and assess its function, failure and repair as a mechanical system. This article reviews the current state of mechanical evaluation of surgical repairs of the failed mitral valve of the heart. This review describes the anatomy and physiology of the mitral valve, followed by the failure of the mitral valve from a mechanical point of view. The surgical methods used to repair failed valves are introduced, while the use of engineering analysis to aid understanding of mitral valve repair is also reviewed. Finally, a section on recommendations for development and future uses of engineering techniques to surgical repair are presented.

Experimental investigation of the flow of bile in patient specific cystic duct models

Three-dimensional scaled-up transparent models of three human cystic ducts were prepared on the basis of anatomical specimens. The measurement of pressure drop across the cystic duct models and visualization of the flow structures within these ducts were performed at conditions replicating the physiological state. The flow visualization study confirmed the laminar nature of the flow of bile inside the cystic duct and values of pressure drop coefficient (Cp) decreased as the Reynolds number (Re) increased. The three tested models showed comparable behavior for the curve of Reynolds number versus the pressure drop coefficient. The results show that the tested cystic ducts have both increased pressure drop and complicated flow structures when compared with straight conduits. High resistance in a cystic duct may indicate that the gallbladder has to exert large force in expelling bile to the cystic duct. For patients with diseased gallbladder, and even in healthy persons, gallbladder is known to stiffen with age and it may lose its compliance or flexibility. A high resistance cystic duct coupled with a stiffened gallbladder may result in prolonged stasis of bile in the gallbladder, which is assumed to encourage the formation of gallstones.

EFFECT OF REFLECTIVE ASSESSMENT ON INTERNALISATION OF CDIO PRINCIPLES

CDIO initiative aims at creating engineers who can engineer through the use of a product life cycle as an educational framework. CDIO’s Standard 11 which refers to the CDIO Skills Assessment focuses on the assessment of student learning in personal, interpersonal, and product and system building skills, as well as in disciplinary knowledge. This paper presents an assessment rubric for a Multidisciplinary Engineering Design module in which the students are required to explicitly reflect on when did they Conceive, Design, Implement and Operate while working in a multidisciplinary team on a given project. To assess the effectiveness of the reflective component of the assessment, two groups of students were surveyed; the first group was assessed on the achievement of their learning outcomes, quality of the project submitted and the interpersonal skills while the second group was asked to reflect on the CDIO process frequently during the semester. The initial results show that asking the students to intentionally analyse their learning experience through the prism of CDIO creates more awareness of the CDIO as a process which can lead to internalisation of the process as a thinking and problem solving technique that can be used when learning other modules that are not design and build by nature.

Flow in Idealised Compliant Human Cystic Duct Models

The functions of the cystic duct and the role of its complicated geometry (in particular the valves of Heister), in the delivery of bile flow have always been a subject of speculation. This paper reports on an experimental investigation of the flow in idealised, compliant cystic duct models. The valves of Heister were idealised using eight semi-circular alternating baffles fitted inside the compliant tubes. These tubes were arranged in configurations representing the anatomical configurations of real cystic ducts. Models both with and without baffles were tested for comparison. The results show that the valves of Heister seem to play a role in facilitating both the filling and emptying of the gallbladder.

From Cystic Duct to Static Mixer: A Serendipitous Journey via Flow Visualization

The cystic duct is a very complicated conduit that connects the gallbladder to the common bile duct. The geometry of the of the cystic duct and its functions, in particular the valves of Heister, in the flow of bile into and out of the gallbladder have always been a subject of speculation. It has been suggested variously that their function is to: impede the flow of bile into the gallbladder, prevent the outflow of bile from the gallbladder, or prevent the collapse of cystic duct. Presented in this paper is the results of a novel experiment to assess the role of the valves of Heister during both the filling and the emptying phases of the gallbladder. The results suggest that the existence of these valves helps both the filling and the emptying of the gallbladder by providing structural support and preventing the duct from total collapse. A surge of pressure upstream of the cystic duct is observed prior to the opening of the cystic duct which is consistent with previous in-vivo biological observations