Surface triangulation for 3-D scene model construction from stereo

The construction of an accurate 3-D scene model is a fundamental aspect of any model-based image coding scheme. This article describes the generation of a triangular facet surface representation from the data acquired by a calibrated binocular (stereo) camera system     

Microstructural changes accompanying repair welding in 5xxx aluminium alloys and their effect on the mechanical properties

At the shipyards, the aluminium alloy 5083 is welded with a multi-pass sequence using the metal inert gas technique. If, while checking the weld integrity either after welding or during service, defects are detected in the vicinity of the weldment, repairs are usually employed to extend the service life.

The repair method involves removal of the upper passes, depending on the thickness and re-welding under the same conditions.

Purpose of this paper is to examine the microstructural changes accompanying repair welding, define their effect on properties of primary importance and set, if possible, an upper limit as far as the number of repairs is concerned.     

Oxidation of oleuropein studied by EPR and spectrophotometry

The autoxidation at alkaline pH and enzymatic oxidation by mushroom tyrosinase of oleuropein, the dominant biophenol present in the fruits and leaves of Olea europea, was followed by both electron paramagnetic resonance (EPR) and absorption spectroscopy. For comparison, the same oxidation processes were applied to 4‐methylcatechol, a simple polyphenol present in olive mill wastewaters. EPR spectra of stable o‐semiquinone radicals produced during autoxidation at pH 12 and short‐lived o‐semiquinone free radicals produced during autoxidation at pH 9.0 or tyrosinase action and stabilized by chelation with a diamagnetic metal ion (Mg²⁺) were recorded for both polyphenols, and the corresponding hyperfine splitting constants were determined. The UV‐Vis spectral characteristics of the oxidation of polyphenols were highly dependent on the type of polyphenol, oxidant type and the pH of the reaction. The kinetic behavior of tyrosinase in the presence of oleuropein and 4‐methylcatechol was followed by recording spectral changes at 400 nm (absorption maximum) over time. The tysosinase activity with oleuropein showed a pronounced pH optimum at pH 6.5 and a minor one around pH 8. From the data analysis of the initial rate at pH 6.5, the kinetic parameters K_m = 0.34 ± 0.03 mM and V_max = 0.029 ± 0.002 ΔA₄₀₀ min^–1 were determined for oleuropein.     

A continuous adjoint method with objective function derivatives based on boundary integrals, for inviscid and viscous flows

A continuous adjoint formulation for inverse design problems in external aerodynamics and turbomachinery is presented. The advantage of the proposed formulation is that the objective function gradient does not depend upon the variation of field geometrical quantities, such as metrics variations in the case of structured grids. The final expression for the objective function gradient includes only boundary integrals which can readily be calculated in both structured and unstructured grids; this is feasible in design problems where the objective function is either a boundary integral (pressure deviation along the solid walls) or a field integral (the entropy generation over the flow domain). The formulation governs inviscid and viscous flows; it takes into account the streamtube thickness variation terms in quasi-3D cascade designs or rotational terms in rotating blade design problems. The application of the method is illustrated through a number of design problems concerning isolated airfoils, a 3D duct, 2D, quasi-3D and 3D, stationary and rotating turbomachinery blades.     

Hybrid TDMA with heuristic traffic shaping: An efficient bandwidth allocation approach for heavy loaded LANs

Hybrid TDMA (Time Division Multiple Access) with heuristic traffic shaping (HyTDMA/HTS) is a new collisionless MAC protocol for efficiently managing the traffic of a heavy loaded broadcast LAN. The protocol employs techniques that enable it to perform better than both fixed assignment protocols like TDMA as well as dynamic bandwidth allocation protocols like LTDMA. HyTDMA/HTS can smoothly operate in diverse traffic environments of very high loads and bursty traffic, and it can still maintain maximum shared medium utilization while maintaining low packet delay times. Built into the protocol is also a simple yet effective heuristic mechanism that regulates the traffic of hosts flooding the network with an excessive number of packets larger than the average.     

A nexus of Cyber-Geography and Cyber-Psychology: Topos/“Notopia” and identity in hacking

This paper explores the Cyber-Psychological and Cyber-Geographic aspects of hacking and hacktivism. An examination of the literature related to hackers and hacking reveals a complex nexus of spatial (including cyber-spatial such as “Notopia”) and psychological aspects of hacking, from which emerges a central question of how humans perceive and manipulate their cyber-identities. Concealing (real and cyber) identities is typical in hacking. With our progressive acculturation with identity-less and place-less modes of existence, our cyber-identities through time may be studied from within John Locke’s criterion of “memory” and the spatial-geographical criterion of identity.     

Hypertension and left ventricular mass index (L.VMI) in patients on regular hemodialysis (RDT)

Background:  Because of high incidence of acquired renal cyst and renal malignancy, it is suggested that spontaneous renal rupture more frequently occurs in patients receiving long‐term hemodialysis than in the general population. This study was performed to evaluate the clinical characteristics of spontaneous renal rupture in hemodialysis patients. Methods:  This retrospective study enrolled 12 hemodialysis patients who developed spontaneous renal rupture. We investigated primary renal disease, duration of dialysis, clinical symptoms and signs, radiologic findings, treatment modalities, and histologic findings. Result:  The mean age of the patients was 54 ± 10 years old and the number of male was 9. Primary renal disease consisted of autosomal dominant polycystic kidney disease (PCKD)(n = 5), chronic glomerulonephritis (n = 2), diabetic nephropathy (n = 1), hypertensive nephropathy (n = 1), unknown cause (n = 3). Presenting symptoms and signs were sudden onset of flank pain in 9 patients and gross hematuria with mild flank pain in 3 patients. Mean duration from initiation of hemodialysis to development of spontaneous renal rupture was 53 ± 36 months. Abdominal computed tomography showed subcapsular or perinephric hematoma in all patients. Of the 7 non‐PCKD patients, 6 patients had multiple acquired renal cysts. Surgical exploration was undertaken in 9 patients. Pathologic examination demonstrated small sized renal cell carcinoma in 2 of 9 patients. Three patients were only treated with conservative management including blood transfusion. All 12 patients recovered without recurrence. Conclusion:  This study demonstrated that genetic or acquired renal cyst was an important cause of spontaneous renal rupture in hemodialysis patients and presenting manifestations were sudden onset of flank pain and gross hematuria.     

The continuous direct-adjoint approach for second order sensitivities in viscous aerodynamic inverse design problems

A novel continuous adjoint approach for the computation of the second order sensitivities of the objective function used in inverse design problems is proposed. In the framework of the Newton method, the proposed approach can be used to efficiently cope with inverse design problems in viscous flows, where the target is a given pressure distribution along the solid walls. It consists of two steps and will, thus, be referred to as the direct-adjoint approach. At the first step, the direct differentiation method is used to compute the first order sensitivities of the flow variables with respect to the design variables and build the gradient of the objective function. At the second step, the adjoint approach is used to compute the second order sensitivities. The final Hessian expression is free of field integrals and its computation requires the solution of N + 1 equivalent flow (system) solutions for N design variables. Since the CPU cost of using the Newton method, with exact gradient and Hessian data at each cycle, becomes prohibitively high, an approach that computes the exact Hessian only once and then updates it in an approximated manner through the BFGS formula, is used instead. The accuracy of the Hessian matrix components, computed using the direct-adjoint approach is demonstrated on the inverse design of a diffuser and a cascade airfoil.