Remote sensing of atmospheric winds using a coherent, CW lidar and speckle-turbulence interaction

Speckle turbulence interaction has the potential for allowing single ended remote sensing of the path averaged vector crosswind in a plane perpendicular to the line of sight to a target. If a laser transmitter is used to illuminate a target, the resultant speckle field generated by the target is randomly perturbed by the atmospheric turbulence as it propagates back to the location of the transmitter-receiver. When a cross wind is present, this scintillation pattern will move with time across the receiver. A continuous wave (cw) laser transmitter of modest power level in conjunction with optical heterodyne detection was used to exploit the speckel turbulence interaction and measure the crosswind. The use of a cw transmitter at 10.6 microns and optical heterodyne detection has many advantages over direct detection and a double pulsed source in the visible or near infrared. These advantages include the availability of compact, reliable and inexpensive transmitters, better penetration of smoke, dust and fog; stable output power; low beam pointing jitter; and considerably reduced complexity in the receiver electronics

Puncture resistance of pressurized and unpressurized glass reinforced Epoxy (GRE) pipes : a phenomenological model of failure mechanisms

Glass reinforced ethylene (GRE) pipes are widely used in the oil and gas sector in Australia owing to their economical/competitive life cycle costs. However, as with all pipelines, GRE pipes face significant risks of external interference by earthmoving equipment where mechanical insult is the result of approximately 50% of pipeline failures. Mechanical tests on un-pressurised pipes were conducted on thick and thin walled GRE pipe samples rated to ANSI Class 600 at different loading rates to study the failure mechanisms. Localised failures due to combined bending and shear with severe delamination under the indenter were observed in thick wall GRE whereas thin walled GRE pipes failed due to buckling away from the point of impact. The finite element analyses results show that GRE pipes fail due to a combination of bending and direct shear at the p oint of impact. Further, the failures are functions of the angle of impact and the tip geometry. The magnitude of puncture resistance as well as the location of failure and failure mechanisms were all found to be highly dependent on the pipe wall thickness and applied internal pressure. GRE pipes exhibited 55 to 75% less resistance to puncture as compared with steel pipes of same wall thickness. Hence, most commercially available excavators have the potential to penetrate GRE pipes, so alternative methods must be employed to reduce this risk

Internal positioning system for cardiotocograph (CTG) transducers at Mackay Base Hospital

Gudimetla, PV ORCiD: 0000-0002-9402-1763© 2019 The Authors. Published by Elsevier Ltd. Cardiotocographs (CTG) are essential pieces of medical equipment that assist in the birth suite and during maternity surveillance. These devices require the use of transducers that communicate wirelessly to the CTG and enable an expectant mother to have water births. When the CTG transducers are lost, or misplaced, there is no system that can locate the expensive accessories. Thus, necessitates the need to develop an Internal Positioning System at Mackay Base Hospital. The device that was proposed to be used in the system is an Xbee S68© Wi-Fi RF module designed by DIGI International. This device is capable of communicating to Access Points for the purposes of location tracking only. It was successfully demonstrated on a small home network that the Xbee device was able to transmit/ receive data from characteristic packet signatures which was captured using Wireshark©. Furthermore, to ensure the device can be aligned with IP67 rating an enclosure was designed to enable the device to be immersed in water. Overall it was ascertained that the device is able to connect on a small network, which can be easily applied on a larger WLAN, in addition to all the project outcomes of an Engineering style report was demonstrated

Properties of tough skinned vegetable-pumpkin tissue

Gudimetla, PV ORCiD: 0000-0002-9402-1763Understanding of mechanical behaviour of food particles will provide researchers and designers essential knowledge to improve and optimise current food industrial technologies. Understanding of tissue behaviours will lead to the reduction of material loss and enhance energy efficiency during processing operations. Although, there are some previous studies on properties of fruits and vegetables however, tissue behaviour under different processing operations will be different. The presented paper is a part of FE modelling and simulation of tissue damage during mechanical peeling of tough skinned vegetables. In this study indentation test was performed on peeled and unpeeled samples at loading rate of 20 mm/min for peel, flesh and unpeeled samples. Consequently, force deformation and stress and strain of samples were calculated. The toughness of the tissue also has been calculated and compared with the previous result

Finite element analysis of the interaction between an AWJ particle and a polycrystalline alumina ceramic

Purpose: Abrasive waterjet cutting involves use of a high pressure, abrasive laden waterjet at trans-sonic speeds to cut difficult-to-machine materials. The jet-material interaction depends on the nature of the material being cut, such as ductile or brittle. The brittle regime involves the generation and propagation of microcracks due to impact and many theories have been proposed in this regard. We aim to resolve the nature of the generation and propagation of cracks in such phenomena using the finite element analysis methodology.\ud Design/methodology/approach: A 3-dimensional FE model was set up using PATRAN. The alumina ceramic was modelled as a 1-mm cube while a 0.1mm diameter half sphere was used to model a single abrasive particle. The system was imported into ABAQUS and an explicit analysis was performed. The element deletion method was used after invoking a failure criterion to estimate the number of elements removed due to a single impact. The aggregate volume of eroded material was then calculated by multiplying the number of elements removed with the volume of each element. The results of the FEA were compared with the brittle model proposed\ud by Kim & Zeng [12].\ud Findings: The results of the FEA indicate that mixed-mode failure is the most common form of failure in such interactions. The volume of material removed per impact from the FE results is close to 16% of those predicted by Kim & Zeng’s model.\ud Research limitations/implications: The finite element framework presented is idealized for the case of regular cubes based on a set of assumptions.\ud Originality/value: This finite element approach is a good tool to study the nature of interaction between a microscopic particle and a brittle material and accurately predict the erosion mechanisms in such interactions

Beyond the technical skills: A case for internationalization of graduate attributes in PhD programs

Gudimetla, PV ORCiD: 0000-0002-9402-1763Internationalization of curriculum (IoC) has garnered momentum, with many universities around the world now viewing graduate students as global citizens. One aspect of IoC that lacks clarity is the students’ perception of internationalization of graduate attributes. In this study, we explored graduate student’s perceptions of the graduate attributes that need to be included in the curriculum to become internationalized. Advanced stage PhD students (n=6) were interviewed about the relevance of internationalization of specific graduate attributes. A set of six specific questions were posed in the interview that was conducted as a group discussion and was recorded and transcribed. 5 out of 6 students observed that schools, faculties, and universities need to sponsor workshops and seminars regularly which will help students absorb attributes such as cultural and religious tolerance, societal awareness, stress management, building resilience which will help them fit well into any work environment. Another important factor was the need for more exchange programs and conference participation that will expose them to different work environments worldwide and help them recognize how their peers approach similar endeavors. Our study offers insights into what aspects of graduate attributes need to be addressed at the faculty and university levels to promote the IoC. © 2019 by authors, all rights reserved

Modelling and simulation of performance and combustion characteristics of diesel engine

Gudimetla, PV ORCiD: 0000-0002-9402-1763; Nabi, M ORCiD: 0000-0002-4087-930X; Rasul, M ORCiD: 0000-0001-8159-1321The main objective of this study was to develop a thermodynamic model to analyse engine performance and combustion behavior of a single cylinder, four-stroke, naturally aspirated, direct injection (DI) diesel engine. The model was developed with a commercial GT-Power software. Various sub-models for different systems including intake, exhaust, fuel injection, combustion, and heat transfer rate were combined for thermodynamic analysis of engine performance and combustion behaviour. The engine rotational speed, start of injection timing and compression ratio were considered as variables. The engine rotational speeds were varied from 800 rpm to 2500 rpm, the start of injection timings was ranged from 15o crank angle (CA) before top dead centre (bTDC) to 15o CA after top dead centre (aTDC), and the compression ratios were changed from 13 to 25. Performance parameters such as indicated and brake power, brake thermal efficiency, friction, etc. and combustion parameters such as heat transfer rate and in-cylinder pressure are analysed at different engine rotational speed, injection timing, and compression ratio, and discussed accordingly. The optimum performance such as BTE, BT and BMEP were found at the engine speed of 1700 rpm, a start of injection timing of 10o bTDC, and a compression ratio of 20. © 2019 The Authors. Published by Elsevier Ltd

Anisotropic non-Kolmogorov turbulence phase screens with variable orientation

We describe a modification to fast Fourier transform (FFT)-based, subharmonic, phase screen generation techniques that accounts for non-Kolmogorov and anisotropic turbulence. Our model also allows for the angle of anisotropy to vary in the plane orthogonal to the direction of propagation. In addition, turbulence strength in our model is specified via a characteristic length equivalent to the Fried parameter in isotropic, Kolmogorov turbulence. Incorporating this feature enables comparison between propagating scenarios with differing anisotropies and power-law exponents to the standard Kolmogorov, isotropic model. We show that the accuracy of this technique is comparable to other FFT-based subharmonic methods up to three-dimensional spectral power-law exponents around 3.9

Finite element analysis of high strain rate superplastic forming (SPF) of Al–Ti alloys

Presents the numerical results obtained from the finite element analyses of the superplastic forming (SPF) of Al–Ti alloys. The models are used to optimise the process and predict forming times in terms of deformed shapes, stress–strain distributions and thickness evolution across the facets of fully formed surfaces. Unlike earlier studies that have used membrane elements, this is an exercise using shell elements in an attempt to estimate stresses, slip planes and variation of friction coefficients during the forming process. The simulations were validated using previously reported experimental results. The constitutive modelling was based on the elastic–viscoplastic material properties, taking into account the viscous flow parameters of the sheet metal. ABAQUS/standard finite element code was used to simulate the SPF process. The results indicate good correlation amongst the theoretical, experimental and finite element analyses