Academic literature on the topic 'Virtual Range Scans'

This chapter highlights the risks and benefits of transacting business within a virtual environment. It becomes evident that e-business has changed the face of consumer/business interactions. Substantial competitive advantage can be gained by a business engaging in well-managed e-business transactions, while consumers can receive benefits such as cheaper prices, a wider range of products, and more convenient shopping via the internet. The chapter commences with a review of the current literature on scams and online fraud, including an introduction to the role that social networking sites can play in facilitating online scams. Statistics regarding e-business transactions for small and medium-sized Australian enterprises are presented followed by the exploration of two specific types of scams: overpayment scams and online shopping scams. Reported financial loss within Australia during 2010 as a result of these scams totalled AUS$29,710,420. The chapter concludes with the identification of some preventative measures to ensure the transactions occurring in any e-business environment are legitimate, followed by some directions for future research.

Decision making in a complex system requires a large amount of data, and real time interaction and visualization tools become effective solutions. Constant improvement in computer graphics technology has encouraged the research of developing better and more efficient ways of interacting and visualizing complex three-dimensional image data. This paper presents a unique software framework for interacting and visualizing complex volume image data in a virtual environment. For efficient user interactions, a wireless gamepad controller is used as the main input device. The buttons and joysticks on the gamepad controller are intuitively mapped to perform different functions depending on the feature mode that the software is currently in. Apart from the general viewer, an extension of the software also reads in standard format patient medical images such as CT/MRI scans. As an effective decision making tool, the software allows the user to apply fast pseudo-coloring and multiple interactive oblique clipping planes for an immersive detailed examination of any 3D model. In the medical imaging extension of this software, it features the ability for the user to select a specific range of tissue densities to render and an endosurgery planning mode that allows a surgeon to place simulated laparoscopic surgical instruments in a virtual model of the patient. The developed software allows for better interaction with complex volume data for use as a decision making and evaluation tool.

In this study, three-dimensional computational fluid dynamics (CFD) analyses are performed to assess the thermal-hydraulic characteristics of a commercial Gasketed Plate Heat Exchangers (GPHEx) with 30 degrees of chevron angle (Plate1). The results of CFD analyses are compared with a computer program (ETU HEX) previously developed based on experimental results. Heat transfer plate is scanned using photogrammetric scan method to model GPHEx. CFD model is created as two separate flow zones, one for each of hot and cold domains with a virtual plate. Mass flow inlet and pressure outlet boundary conditions are applied. The working fluid is water. Temperature and pressure distributions are obtained for a Reynolds number range of 700–3400 and total temperature difference and pressure drop values are compared with ETU HEX. A new plate (Plate2) with corrugation pattern using smaller amplitude is designed and analyzed. The thermal properties are in good agreement with experimental data for the commercial plate. For the new plate, the decrease of the amplitude leads to a smaller enlargement factor which causes a low heat transfer rate while the pressure drop remains almost constant.

Abstract An integral squeeze film damper (ISFD) offers the advantages of a lower number of parts, a shorter axial span, a lighter weight, a split manufacturing and high precision on its film clearance construction. An ISFD does not only add damping to reduce shaft vibration amplitudes and to enhance the stability of a rotor-bearing system but also can be used to tune a rotor-bearing system natural frequency, and thus increasing the operational safety margin between the running shaft speed and the system critical speed. In spite of the numerous commercial applications, the archival literature is scant as per the experimental quantification of force coefficients for ISFDs. This paper details the results of an experimental and analytical endeavor to quantify and to predict the dynamic force coefficients of an ISFD, hence bridging the gap between theory and practice. With an axial length of 76 mm, the test damper element has four arcuate film lands, 73° in arc extent at a diameter of 157 mm, and each with a clearance (c) equaling to 0.353 mm. As is customary, the damper has its axial ends sealed with end plates produced by a set of installed shims giving an axial gap (d) equal to 1.5c, 1.21c, and 0.8c. A baseline configuration, namely open ends, is also tested without the end seals in place. In the test rig, the ISFD and its housing are flexibly mounted while the rotor is rigid and stationary (no spinning). The lubricant is an ISO VG46 oil supplied at a low pressure, 1 to 2 bar(g) and ∼ 47 °C inlet temperature, typical of compressor applications. The test procedure applies static loads on the ISFD and records the bearing static offset or eccentricity to verify the structure stiffness, and meanwhile, individual hydraulic shakers deliver dynamic loads along two orthogonal directions to produce motions over a set frequency range, 10 Hz to 160 Hz. The ISFD produces direct damping and inertia that increase with the journal static eccentricity albeit at a lower rate than predictions from a computational squeeze film flow model that includes lubricant compressibility. The end seals are effective in significantly raising the damping coefficient while reducing the oil through flow rate. The damper with the tightest sealed ends (d = 0.8c) shows nearly 20 times more damping that the open ends ISFD albeit also revealing a significant stiffness hardening (negative virtual mass) as the excitation frequency increases. On the contrary, the open ends ISFD and the sealed ends configurations with gaps d = 1.21c and 1.5c produce a (positive) virtual mass that exceeds the test element physical mass and thus softens the test element direct dynamic stiffness. For the configurations with loose end seals (d = 1.21c or larger to open ends), the model predicts well the damping coefficients but under predicts the added masses by 50% or more. Note this virtual mass coefficient, largely ignored in practice, can make the test element either extremely stiff as with the sealed damper configuration with the smallest gap d = 0.8c, or very soft as with the ISFD with end seals gap = 1.21c or 1.5c. Hence, designers are cautioned not to pursue overly tight end sealed dampers as the mineral lubricant, nearly incompressible though always having a small amount of entrapped gas, may behave distinctly when confined to a squeezed film volume and having no adequate routes to escape or flow through.