An analytical approach to optimize radial synthetic aperture focusing for volumetric transrectal ultrasound imaging

In this paper, we present a novel analytical approach to optimize radial synthetic aperture focusing framework for high-definite and high-sensitive volumetric transrectal ultrasound imaging (TRUS-rSAF). A closed-form analytical description of beam profile defines spatial resolution and grating lobe positions in the TRUS-rSAF imaging of radial plane and validated by a heuristic testing of the critical parameters. Given the theoretical foundation, we optimize the TRUS-rSAF system configuration to balance the spatial and temporal resolution, grating lobe artifacts, and signal-to-noise ratio (SNR) in radial plane with a design criterion to outperform a clinical volumetric TRUS (TRUS-REF) imaging. The results showed that the proposed analytical optimization provides significant improvements of imaging quality in radial plane even over an in-plane microconvex TRUS imaging. Therefore, our analytical approach provides a optimal framework for effective TRUS-rSAF imaging in clinics.

An analytical approach to optimize radial synthetic aperture focusing for volumetric transrectal ultrasound imaging

In this paper, we present a novel analytical approach to optimize radial synthetic aperture focusing framework for high-definite and high-sensitive volumetric transrectal ultrasound imaging (TRUS-rSAF). A closed-form analytical description of beam profile defines spatial resolution and grating lobe positions in the TRUS-rSAF imaging of radial plane and validated by a heuristic testing of the critical parameters. Given the theoretical foundation, we optimize the TRUS-rSAF system configuration to balance the spatial and temporal resolution, grating lobe artifacts, and signal-to-noise ratio (SNR) in radial plane with a design criterion to outperform a clinical volumetric TRUS (TRUS-REF) imaging. The results showed that the proposed analytical optimization provides significant improvements of imaging quality in radial plane even over an in-plane microconvex TRUS imaging. Therefore, our analytical approach provides a optimal framework for effective TRUS-rSAF imaging in clinics.

Improved diagnostic accuracy for ulnar-sided TFCC lesions with radial reformation of 3D sequences in wrist MR arthrography

Objectives Triangular fibrocartilage complex (TFCC) injuries frequently cause ulnar-sided wrist pain and can induce distal radioulnar joint instability. With its complex three-dimensional structure, diagnosis of TFCC lesions remains a challenging task even in MR arthrograms. The aim of this study was to assess the added diagnostic value of radial reformatting of isotropic 3D MRI datasets compared to standard planes after direct arthrography of the wrist. Methods Ninety-three patients underwent wrist MRI after fluoroscopy-guided multi-compartment arthrography. Two radiologists collectively analyzed two datasets of each MR arthrogram for TFCC injuries, with one set containing standard reconstructions of a 3D thin-slice sequence in axial, coronal and sagittal orientation, while the other set comprised an additional radial plane view with the rotating center positioned at the ulnar styloid. Surgical reports (whenever available) or radiological reports combined with clinical follow-up served as a standard of reference. In addition, diagnostic confidence and assessability of the central disc and ulnar-sided insertions were subjectively evaluated. Results Injuries of the articular disc, styloid and foveal ulnar attachment were present in 20 (23.7%), 10 (10.8%) and 9 (9.7%) patients. Additional radial planes increased diagnostic accuracy for lesions of the styloid (0.83 vs. 0.90; p = 0.016) and foveal (0.86 vs. 0.94; p = 0.039) insertion, whereas no improvement was identified for alterations of the central cartilage disc. Readers’ confidence (p < 0.001) and assessability of the ulnar-sided insertions (p < 0.001) were superior with ancillary radial reformatting. Conclusions Access to the radial plane view of isotropic 3D sequences in MR arthrography improves diagnostic accuracy and confidence for ulnar-sided TFCC lesions. Key Points • In multi-compartment arthrography of the wrist, ancillary radial plane view aids assessability of the foveal and styloid ulnar-sided insertions of the triangular fibrocartilage complex. • Assessment of peripheral TFCC injuries is more accurate with access to radial multiplanar reconstructions. • Additional radial planes provide greater diagnostic confidence.

The separation wall effect of a volute twin entry cross section area on the mixed inflow turbine performance

The pulse turbocharging system is used in many diesel engines and it is fortunate that nozzleless mixed turbines allow unsteady flow with less performance losses. It operates with a double or sometimes triple-entry casing creating different flow regimes in each sector. A nozzleless casing is used. The division of the cross section area takes the form of a solid wall in the radial plane. When the flow rate through one or the other volute inlet drops to zero, some reverse flow is observed from the other inlet. This situation suffers undesirable effects, diminishing the benefits of the divided volute casing types. A numerical investigation on the effect of the length of the dividing wall in the radial plane is performed using the ANSYS code. This possibility is explored and the results show that extending the wall to a limiting length enhances the flow behavior with better performance.

Dynamic model of closure the liner

Annotation Purpose. Develop analytical dependences for modeling the speed and dynamics of deformation of liner depending on its design parameters and physical and mechanical characteristics, taking into account the technological parameters of the process. Methods. Based on the system of geometric equilibrium equations for a cylindrical shell, taking into account the isotropy of the medium and the momentless stress state, the spatial action of forces and pre-tension of the liner, developed analytical equations that allow modeling the dynamics of deformation of liner in time, which allows to determine the time constant of the system “liner – milking cup”. Results. Analytical dependences of the dynamics of deformation of liner in time in the radial plane and the rate of deformation depending on its design parameters and physical and mechanical characteristics of the material are developed. Parameters for deformation simulation are: R – radius of liner, Е – modulus of elasticity, ρ – the density of the rubber material, h – thickness of liner, рн – vacuum pressure, l – the length of the active part of liner, ν – Poisson's coefficient for rubber, Fн – force of tension of liner. Depending on the central angle in the radial plane of the section, the shape of the deformation of the liner is modeled along its entire working length during the closing and opening stroke. Conclusions. The obtained dependences allow to model the dynamics of deformation of liner in the radial plane depending on its design parameters and physical and mechanical characteristics of the material. The developed analytical dependences take into account the pre-tension of the liner, vacuum pressure and allows modeling depending on the central angle in the radial plane of the rubber section. The use of the developed analytical dependences makes it possible to substantiate the main parameters that affect the process of closing and opening of the liner. The characteristic of the deformation in the cross section of the largest deformation is that the tension of the liner does not affect the deformation characteristic. This is due to the isotropy property of the cylindrical shell and the elastic isotropic properties. Keywords: liner, vacuum pressure, modulus of elasticity, radial deformation, coordinate system, tension of rubber, the cylindrical shell, the isotropic medium.

Improved Radial Plane Fins Heat Sink for Light-Emitting Diode Lamps Cooling

A numerical study is conducted concerning the improvement of radial plane fins heat sinks for natural convection cooling of light-emitting diode (LED) lamps. The main objective is to maintain the temperature of the heat sink base below a prescribed threshold for a given released heat flux at the heat sink, minimizing its mass and maintaining at a reasonably simple level the manufacturing processes and operations required for its production. Starting from a previously optimized heat sink for the same purpose, constituted by complete rectangular radial plane fins, the present study aims at further improvements by considering incomplete rectangular radial plane fins. The main objective of this study is to find the best profile for the turning operation to obtain the radial plane fins lighter configuration. It is found that this can be achieved by removing part of the upper internal corners of the rectangular fins, more specifically shaping a curved cut, leading to heat sink mass reduction up to 32.4%. The geometry of the improved heat sink is of cylindrical nature, obtained from cutting an aluminum extruded bar comprising a cylindrical central core and a number of uniformly distributed rectangular radial plane fins, followed by a simple turning operation to remove their upper internal corners. Even if results concern a particular LED lamp, the main ideas and approach prevail to improve other types of heat sinks for general light and/or electronic components cooling.