Fabrication of ceramic and ceramic composite microcomponents using soft lithography

This PhD project is set out to develop a high precision ceramic fabrication approach suitable for mass production, and to meet the needs of microengine application. A group of new processes have been developed and the results are characterized for fabrication of high precision ceramic oxides and composite microcomponents using soft lithography and colloidal powder processing. The materials chosen in the research are alumina, yttria stabilised zirconia and their composite for their excellent properties at high temperature

Planning, operation, and design of market-based virtual power plant considering uncertainty

The power systems of today seem inseparable from clean energy sources such as wind turbines (WTs) and photovoltaics (PVs). However, due to their uncertain nature, operational challenges are expected when WT and PV energy is added to the electricity network. It is necessary to introduce new technologies to compensate for the intermittent nature of renewable energy sources (RESs). Therefore, rationally implementing a demand response (DR) program with energy storage systems (ESSs) in a virtual power plant (VPP) environment is recommended as a way forward to minimize the volatile nature of RESs and improve power system reliability. Our proposed approach aims to maximize social welfare (SW) (i.e., maximization of consumer benefits while minimizing energy costs). Our method assesses the impact of the DR program on SW maximization. Two scenarios are examined, one with and one without a DR program. Stochastic programming theory is used to address the optimization problem. The uncertain behavior of WTs, PVs, and load demand is modeled using a scenario-based approach. The correctness of the proposed approach is demonstrated on a 16-bus UK generic distribution system. Our results show that SW and active power dispatch capacity of WT, PV, and ESS are fairly increased using the proposed approach

Microfabrication of net shape zirconia/alumina nanocomposite micro parts

Recently, there are growing demands in manufacturing of net shape micro parts for wide range of applications due to the increasing interest in miniaturization. In this paper, the fabrication of tetragonal phase zirconia/alumina (YSZ/Al2O3) nanocomposite micro-parts with high quality is presented. The fabrication process is based on soft lithography and colloidal powder dispersion. Experimental results showed that by optimizing the soft lithography and the dispersion process, it was possible to produce high-resolution micro-parts with well dispersed alumina. The X-ray diffraction results had confirmed the important role of the alumina particles in eliminating the emergence of monoclinic phase while the microstructures reveal a pure tetragonal phase. In addition, the sintered YSZ/Al2O3 micro parts achieved micro hardness with 20% superior to the pure YSZ sintered micro-parts with the addition of 5% alumina

Powder-based laser hybrid additive manufacturing of metals:a review

Recent advances in additive manufacturing (AM) have attracted significant industrial interest. Initially, AM was mainly associated with the fabrication of prototypes, but the AM advances together with the broadening range of available materials, especially for producing metallic parts, have broaden the application areas and now the technology can be used for manufacturing functional parts, too. Especially, the AM technologies enable the creation of complex and topologically optimised geometries with internal cavities that were impossible to produce with traditional manufacturing processes. However, the tight geometrical tolerances along with the strict surface integrity requirements in aerospace, biomedical and automotive industries are not achievable in most cases with standalone AM technologies. Therefore, AM parts need extensive post-processing to ensure that their surface and dimensional requirements together with their respective mechanical properties are met. In this context, it is not surprising that the integration of AM with post-processing technologies into single and multi set-up processing solutions, commonly referred to as hybrid AM, has emerged as a very attractive proposition for industry while attracting a significant R&D interest. This paper reviews the current research and technology advances associated with the hybrid AM solutions. The special focus is on hybrid AM solutions that combine the capabilities of laser-based AM for processing powders with the necessary post-process technologies for producing metal parts with required accuracy, surface integrity and material properties. Commercially available hybrid AM systems that integrate laser-based AM with post-processing technologies are also reviewed together with their key application areas. Finally, the main challenges and open issues in broadening the industrial use of hybrid AM solutions are discussed. 2021, The Author(s).The authors would acknowledge the support received from the ESIF/ERDF Smart Factory Hub (SmartFub) programme in West Midlands. The authors also acknowledge the support received from Yamazaki Mazak, DMG MORI, LASEA and Systems 3R for establishing the hybrid AM facilities at the University of Birmingham.Scopu

Link between distal sensory polyneuropathy, insulin-like growth factor-I and bone mineral density in elderly diabetics

Background: The association between Distal Sensory Polyneuropathy (DSP) and systemic osteopenia was studied before in type 1 Diabetes Mellitus (DM), however, is not all clear, with scanty researches in type 2 DM. In addition, Insulin-like Growth Factor-I (IGF-1) could be the most important mediator of bone growth, and an important neurotrophic factor for peripheral sensory neurons. Therefore, the aim of this study was to study the association between bone mineral density (BMD) and DSP, in elderly patients with type 2 DM, and the link between IGF-1 and both BMD and DSP.Methods: Eighty eight elderly patients, aged ≥60 years, were involved in this case (43 diabetics with DSP and 17 diabetics without DSP) - control (28 non diabetics) study. BMD and IGF-1 were measured.  Results: There was no significant difference between cases and controls regarding T score of either lumbar spine or femoral neck or IGF-1 (P = 0.83, 0.96 and 0.17 consecutively). DM without DSP had higher IGF-1 than both DM with DSP& the control group (P = 0.011 and 0.010 consecutively). IGF-1 was a significant predictor of T score of both femoral neck and lumbar spine, only in the control group (P = 0.008 and <0.001 consecutively) (OR=1.44 and 2.4 consecutively) (CI=1.1-1.9 and 1.9-3.1 consecutively). Neither DSP nor IGF-1 was (were) a significant predictor of BMD in diabetics.Conclusion: There was no association between type 2 DM and BMD. IGF-1 was higher in diabetics without DSP than those with DSP or the control group. IGF-1 was a positive predictor of BMD only in the control group.

Additive manufactured sandwich composite/ABS parts for unmanned aerial vehicle applications

Fused deposition modelling (FDM) is one of most popular 3D printing techniques of thermoplastic polymers. Nonetheless, the poor mechanical strength of FDM parts restricts the use of this technology in functional parts of many applications such as unmanned aerial vehicles (UAVs) where lightweight, high strength, and stiffness are required. In the present paper, the fabrication process of low-density acrylonitrile butadiene styrenecarbon (ABS) with carbon fibre reinforced polymer (CFRP) sandwich layers for UAV structure is proposed to improve the poor mechanical strength and elastic modulus of printed ABS. The composite sandwich structures retains FDM advantages for rapid making of complex geometries, while only requires simple post-processing steps to improve the mechanical properties. Artificial neural network (ANN) was used to investigate the influence of the core density and number of CFRP layers on the mechanical properties. The results showed an improvement of specific strength and elastic modulus with increasing the number of CFRP. The specific strength of the samples improved from 20 to 145 KN&#183;m/kg while the Young&#8217;s modulus increased from 0.63 to 10.1 GPa when laminating the samples with CFRP layers. On the other hand, the core density had no significant effect on both specific strength and elastic modulus. A case study was undertaken by applying the CFRP/ABS/CFRP sandwich structure using the proposed method to manufacture improved dual-tilting clamps of a quadcopter UAV