Hand-Carried Ultrasonography Instrumentation in the Diagnosis of Temporomandibular Joint Dysfunction

Internal derangement (ID) in the temporomandibular joint (TMJ) is defined as a mechanical problem of the joint that interferes with its function. It is attributed to an abnormal interaction among the articular disc, condyle, and joint eminence. The aim of this study is to evaluate diagnostic efficacy of non-invasive hand-carried ultrasonography instrumentation (US) to provide high-level images for a correct diagnosis of ID. Twenty-eight ID patients, 15 female and 13 males, were examined both clinically and by MRI images in order to achieve a diagnosis of ID (using Helkimo index). Then, they were submitted to US examination with a 12 MHz transducer by using hand-carried instrumentation by a clinician that was blind to their diagnosis and clinical data. TMJ US examination was performed with the mouth closed and mouth open, with proper technique. Each position was then evaluated with two different orientations of the transducer. US showed acceptable results in identifying bone structures. Lower values of diagnostic efficacy were obtained for disc position during joint movements with respect to MRI images. MRI still represents the gold standard for the identification of joint structures. If not corroborated by clinical and anamnestic data, the diagnostic efficacy of US in identifying the position of the disc during opening and closing jaw movements appears limited than compared to MRI.

Numerical Modelling of Microwave Heating Assisted Rock Fracture

This paper presents a numerical study on the effects of microwave irradiation on the mechanical properties of hard rock. More specifically, the weakening effect of microwave heating induced damage on the uniaxial compressive and tensile strength of granite-like rock is numerically evaluated. Rock fracture is modelled by means of a damage-viscoplasticity model with separate damage variables for tensile and compressive failure types. We develop a global solution strategy where the electromagnetic problem is solved first separately in COMSOL multiphysics software, and then provided into a staggered implicit solution method for the thermo-mechanical problem. The thermal and mechanical parts of the problem are considered as uncoupled due to the dominance of the microwave-induced heat source. The model performance is tested in 2D finite element simulations of heterogeneous numerical rock specimens subjected first to heating in a microwave oven and then to uniaxial compression and tension tests. According to the results, the compressive and tensile strength of rock can be significantly reduced by microwave heating pretreatment.

100-years’ story of success: photoelasticity — LSR–MICE – MSUCE

Introduction. The 100-years’ history of MICE – MSUCE is also a history of establishment and flourishing of one of the world’s most powerful experimental school of development and application of the photoelasticity method in the investigation of the stress state of civil and special structures. Reliable forecast of the stress state of buildings and structures under static, thermal and dynamic impacts is an indispensable prerequisite of safe operation provision of civil structures during the construction and the operation. The photoelasticity method, allows, along with the analytical methods of the mechanical science, for continual study of the stress state of the object under test, being an experimental method efficiently used both in “standalone” mode and in conjunction with numerical methods. The goal and the objectives hereof: a retrospective development review of the photoelasticity method, in particular, of the contribution of LSR of MICE, and the assessment of the contemporary state of the method in terms of its actuality, novelty and practical significance of mechanical problem solutions, of stress-strain state studies of structures and buildings. Materials and methods. The subject hereof is the polarized light method or the photoelasticity method: development, problematics, solution methods of mechanical problems and studies of structures, applications. Results. The paper describes solution examples of vital problems by the photoelasticity method: stress analysis in the wedge-shaped notch zone of the area boundary, stress state problem under forced deformation in the block-basement contact area, stress state study of underground hydropower plant tunnel with the weir erected by pinpoint blasting. The performed analysis of the photoelasticity method and its contemporary level illustrates the opportunities provided by the method in solving of mechanical problems and in structural studies. Conclusions. Is the experimental school of the photoelasticity method of LSR–MICE – MSUCE really the sunk Atlantis? The development of the experimental mechanics of deformable solid bodies is characterized by progressive proximity of experimental and numerical analysis research methods. The physical modelling, in particular, the polarized light method, allows for obtaining stress-strain state diagrams of structures, or solutions of mechanical problems, feasible for assessment or for calculation result corrections, that is why the polarized light method retains actuality and practical significance. The development of the deformable solid body mechanics determines the significance of the physical modelling, including the polarized light method. The benefit of the polarized light method is the continuity of mechanical problem solutions which is especially important when local areas with specific features of the stress strain behaviour are considered. Modern technologies of material property studies, invention of new materials lead to creation of new mechanical models, for adequacy assessment of which physical modelling methods are required, in particular, the polarized light method.

Simulation of chemo-thermo-mechanical problems in cement-based materials with Peridynamics

A chemo-thermo-mechanical problem is solved using a peridynamic approach to investigate crack propagation in non-reinforced concrete at early-age. In the present study, the temperature evolution and the variation of the hydration degree in conjunction with the mechanical behaviour of cement-based materials are examined. Firstly, a new peridynamic model is introduced to solve fully coupled chemo-thermal problems by satisfying thermal equilibrium condition and hydration law simultaneously and then the effects of the chemo-thermal analysis are imposed in the mechanical framework to investigate all the interactions. The proposed approach is used to solve 2D chemo-thermo-elastic problems and then it is applied to investigate the fracture of concrete structures. Additionally, we examine the accuracy of the method by comparing the crack paths, temperature and hydration degree with those achieved by applying other numerical methods and the experimental data available in the literature. A good agreement is obtained between all sets of results.

Quality Control for The Maintenance Organization in Clark Pampanga for Line Maintenance

Unscheduled maintenance happens where an unknown problem occurs that is not in the schedule of tasks to be performed by a mechanic unlike scheduled maintenance, line maintenance is done every landing and before take-off of the aircraft and in some cases due to technical and mechanical problem observed and detected during line maintenance cancellation of flight is implemented and a declaration of AOG “Aircraft on Ground” meaning the aircraft will be grounded until the time that the aircraft can meet the standards of airworthiness.

Desain dan Implementasi Sistem Navigasi pada Automated Guided Vehicle (AGV)

This research aims to build mechanical system of Automated Guided Vehicle (AGV) and navigation system for AGV. The navigation system consists of RFID reader and rotary encoder. The testing result show that mechanical system of AGV was successfully finished. There is a mechanical problem on drive system of AGV. Each part of navigation system works well according to design. Line sensor can be used for path detection with the given threshold values. Encoder can be used to measure the speed of AGV with the maximum error accuracy less than 2 rpm. This result shows that every part of AGV is ready to run localization and navigation algorithm, even though, it needs to do some improvement on driving parts.

Thermo-electro-mechanical modeling of spark plasma sintering processes accounting for grain boundary diffusion and surface diffusion

In the present research, a numerical modeling approach of the initial stage of consolidation during spark plasma sintering on the microscopic scale is presented. The solution of a fully coupled thermo-electro-mechanical problem also accounting for grain boundary and surface diffusion is found by using a staggered way. The finite-element method is applied for solving the thermo-electro-mechanical problem while the finite-difference method is applied for the diffusion problem. A Lagrange-based non-linear formulation is used to deal with the detailed description of plastic and creep strain accumulation. The numerical model is developed for simulating the structural evolution of the involved particles during sintering of powder compacts taking into account both the free surface diffusion of the particles and the grain boundary diffusion at interparticle contact areas. The numerical results obtained by using the two-particle model—as a representative volume element of the powder—are compared with experimental results for the densification of a copper powder compact. The numerical and experimental results are in excellent agreement.