/library/oar/handle/123456789/79841 2025-12-27T14:59:53Z 2025-12-27T14:59:53Z /library/oar/handle/123456789/118959 2024-02-22T10:24:11Z 2021-01-01T00:00:00Z

Title: Development of an intent interpretation system for a minimal anthropomorphic prosthetic hand Abstract: Upper-limb amputation brings about its challenges, including loss of identity as well as independence. Several prosthetic hands have been developed to aid amputees with regaining normal function following their traumatic experience, however, acceptance of such foreign body extensions is challenging. This is especially true when the chosen artificial limb poses a number of operational limitations whilst feeling unnatural. This results in a reduction of the overall experience whilst posing the risk of device rejection. In order to satisfy the end user with an innovative intent interpretation system to be used with an anthropomorphic prosthetic hand, the ultimate objective of this research project was to carry out a systematic exercise to seek a practical solution for the framework which best addresses a trade-off problem between simplicity, dexterity and usability. This problem was mainly addressed by investigating surface electromyography signal acquisition methods in relation to isometric and anisometric contractions which led to the choice of using transient signals for motion identification and steady-state signals for force estimation. The intent interpretation framework was also developed with the ability of reliably detecting movement phases from no movement phases, only triggering a classifier to make a motion prediction with true movement detection. A classifier was designed to distinguish between four specifically chosen motions from a rest or neutral state, providing the amputee with the capability of performing a large percentage of activities of daily living. Most importantly, the system was set to recognise human instructions in the most simple and intuitive manner to humans. The intent interpretation framework was designed to be user-specific and five normal limbed subjects and two transradial amputees performed offline, episodic experiments which resulted in successful statistical results on the movement detection and identification performance of the system. Successful inter-session performance, as well as force estimation performance results were also obtained through further episodic, continuous and force estimation tests performed by a smaller subject pool. A successful maximised trade-off between the three important attributes was achieved through this framework, which is capable of exploiting the natural human sense of intuition, whilst still providing the end-user with the capability of performing a vast majority of daily tasks in a reliable and practical way. Description: M.Sc.(Melit.)

2021-01-01T00:00:00Z /library/oar/handle/123456789/103123 2022-10-27T10:19:18Z 2021-01-01T00:00:00Z

Title: A study on the firing of sourced Maltese clay into a usable product Abstract: The aim of this dissertation is to study the production of pottery from sourced Maltese clay through experimental firing. The clay sample was sourced from Il-Qolla hill in the vicinity of Rabat, Malta. The samples were then sieved through two different mesh sizes: 63 µm and 125 µm. The briquettes were manufactured from the sieved and dried clay and subsequently fired at temperatures of 500, 700 and 900 °C, with soaking times of 30 and 120 minutes, in both oxidising and reducing conditions. The mineralogical and structural modifications to the fired clay were examined by X-ray powder diffraction (XRPD) as well as optical and scanning electron microscopy (SEM). Finally, a Knoop hardness test was conducted to evaluate the hardness of the fired clay samples. The colour, porosity and voids, microstructure, mineralogy, and material hardness, were all observed to alter with increasing firing temperature. This highlights that firing temperature is the parameter which affects the outcome of the fired clay more than all other criteria considered in this study. An increase in firing temperature resulted in sintering and transformation to a more compact structure. Calcite was observed to decompose in the temperature range of 900 °C, forming calcium oxide, which reacted with the quartz present in the microstructure to form wollastonite in the process. Briquettes fired at higher temperatures exhibited a harder microstructure, showing that the ceramic transformation has occurred more completely. Ceramics fired in oxidising conditions exhibited higher hardness results than those fired in reducing conditions. Description: B.Eng. (Hons)(Melit.)

2021-01-01T00:00:00Z /library/oar/handle/123456789/98771 2022-07-11T06:01:10Z 2021-01-01T00:00:00Z

Title: Development and implementation of a wireless inductive power transfer system Abstract: Wireless charging methods have recently uncharted new terrain. The upgrading of commercial products warrants a tenable solution for the charging bottleneck inherent in traditionally portable battery-powered electronics. Since any technology by default requires a source of electricity, the uses of wireless power transmission systems are virtually endless. Wireless charging of hand-held electronics is currently the most popular implementation but it is not the only valid alternative. Such a transfer system may be used in a variety of applications, from household items to large commercial applications, providing improved comfort and a better degree of protection from the electrical source. At this time, the most well-known standard is the Qi international wireless charging standard, which utilizes magnetic induction to provide cordless power to small equipment up to 15W. The Wireless Power Consortium has introduced the Ki Cordless Kitchen standard, which provides wireless power to appliances everything from low-powered juicers to kettles and other heating appliances that require up to 2.2kW of power. The transmitter for power transmission, the inductive coils in this case as the antenna, receiver, and the rectifier to convert AC to DC are the four components of a wireless power transfer system. This dissertation presents the design and implementation of a wireless inductive power transfer (WIPT) system. In order to bridge the gap between current standards and a higher power system, two approaches were taken. The first system consists of a WIPT system using the Qi standard. The second system comprises a high power WIPT system. The research methodology was set up to guarantee that each module could be thoroughly tested to ensure that its objective in the overall system design is achieved. Description: M.Sc.(Melit.)

2021-01-01T00:00:00Z /library/oar/handle/123456789/98759 2022-07-11T05:59:35Z 2021-01-01T00:00:00Z

Title: Fabrication of biodegradable porous scaffolds by an extrusion-based additive manufacturing technique Abstract: As life expectancy is steadily increasing over the years, bone disorders are becoming a prevalent concern among senior citizens. Unfortunately, the main regenerative treatments for bone defects are often associated with a slew of complications and extensive recovery periods. Consequently, the main motive behind this study was to address these limitations by developing a porous metallic scaffold that is composed of pure iron via an extrusion based additive manufacturing technique. A novel fabrication route was adopted for the construction of bone scaffolds. Initially, two separate powder mixtures, one composed of iron and another made of sodium chloride, were prepared. With each individual powder, various binder constituents were added and homogenously mixed until a unique feedstock was created. These mixtures were then extruded in a sequential order to create an alternating pattern of cylindrical struts. Successive layers of these extrudates were deposited at right angles to one another until a three dimensional structure was created. The binder constituents were then removed and the structure was heated to a temperature of 750°C which caused the salt powder to fuse together. Once it cooled, the structure was immersed in water to dissolve the salt and form a porous metallic structure. Subsequently, it was reheated to a temperature of 1200°C where the iron powder sintered and formed the resultant metallic scaffold. In this study, numerous feedstocks were developed and tested in an attempt to find a suitable binder system for each powder. Results indicated that feedstocks with a higher powder to binder ratio produced extrudates with enhanced shape retention after subjected to the final sintering process. Despite that, feedstocks composed of a higher powder loading proved to cause extrusion concerns, particularly with nozzle blockage. The effects of feedstock constituents and heat treatment on powder densification was also studied. Characterisation techniques indicated that satisfactory interparticle bonding was achieved between the powders which resulted in enhanced structural integrity. Nevertheless, small spherical formations were formed in several areas across the microstructure, which were later identified by energy dispersive spectroscopy as contaminants. Collectively, this study made it evident that the novel fabrication route exhibited great potential to develop porous iron scaffolds. Description: M.Sc.(Melit.)

2021-01-01T00:00:00Z