Computer Simulation of Optimal Lipped Polyethylene Liner Orientation Against Prosthetic Impingement

Background: Lipped or elevated acetabular liners are to improve posterior stability and are widely used in hip arthroplasty. However, concerns of increasing impingement exist when using such liners and optimal orientation of the elevated rim remains unknown. We aimed to identify the impact of lipped liner on the range of motion (ROM) before impingement and propose its optimal orientation.Methods: An isochoric three-dimensional model of a general hip-replacement prosthesis was generated and flex-extension, add-abduction, axial rotation was simulated on a computer. The maximum ROM of the hip was measured before the neck impinged on the liner. Different combinations of acetabular anteversion angles ranging from 5 to 30 degrees and lipped liner orientations from posterior to anterior were tested. Results: When acetabular anteversion was 10 or 15 degrees, placing the lip of the liner in the posterosuperior of the acetabulum allowed satisfactory ROM in all directions. When acetabular anteversion was 20 degrees, extension and external rotation were restricted. Adjusting the lip to the superior restored satisfactory ROM. When acetabular anteversion was 25 degrees, only placing the lip into the antero-superior could increase extension and external rotation to maintain satisfactory ROM.Conclusions: This study showed that optimal lipped liner orientation should be depend on acetabular anteversion. When acetabular anteversion was smaller than 20 degrees, placing lip in the posterior allowed an optimally ROM. When acetabular anteversion was greater than 20 degrees, adjusting lip to the anterior allowed a comprehensive larger ROM to avoid early impingement.

The orientation of residential development in Mashhadthat takes account of daylight

Introduction. Due to population growth and urbanisation, energy consumption by urban buildings, especially in developing countries, is increasing dramatically. Limited energy resources and the need to save on consumption necessitate the optimal design in the field of residential development. Building walls are an important boundary between indoor and outdoor spaces, since daylight has a direct impact on energy consumption in buildings. The optimal use of daylight in living spaces reduces energy consumption dramatically. In this regard, the proper orientation of residential buildings is an effective method of energy consumption optimisation. If the layout of an urban development fits the climate of a region, residential buildings are constructed with account taken of the optimal orientation to daylighting. Materials and methods. The aim of this study is the optimal orientation of a part of residential development in Mashhad. To achieve the goal of the study, comprehensive studies of the city of Mashhad and its environs were conducted and Mashhad climate data were collected. Hence, daylight scattering was analysed for a given area with regard to the optimal angle of orientation to daylighting. Daylight was analysed in the two modes, including the present-day layout and the angular position (the north side), that were compared later. The study area has the angle of 20 degrees from the north to the west. All analyses and simulations were performed on the longest (June 22) and shortest (December 22) days of the year using parametric software programmes Grasshopper and Ladybug. Results. A comparative analysis of the two modes shows that the study area, located in the north, receives more daylight, regardless of the angle of rotation. Mashhad summers are hot and dry, and winters are cold and humid; a lot of light can penetrate into buildings during the hot season. In winter, overshadowing by buildings does not allow enough daylight due to the unfavourable location of the residential development. According to the standard, the optimal rotation angle of buildings in Mashhad varies from 5 degrees northeast to 20 degrees northwest. Conclusions. The results show that the optimal daylight orientation in Mashhad is 20 degrees southeast. This value is in the standard range for the residential orientation, and the amount of light, received in summer and winter seasons, is proportional to the needs of indoor space users; natural lighting makes residential spaces more comfortable and reduces energy consumption.

Optimization of the Euro-Asian network of gravitational detectors for detecting the radiation of collapsing objects

A Euro-Asian network of four gravitational-wave (GW) interferometers is considered, taking into account the plan to create such a detector in Novosibirsk. The efficiency of the network is assessed by typical numerical criteria, which also depend on the characteristics of the received signal. In this work, we calculate the optimal orientation of the Novosibirsk detector for the problem of detecting GW radiation accompanying the collapse of the progenitor star with an initial angular momentum. The specificity of the scenario is the presence of the so-called. bar stage deformation, for which the shape of the emitted GW signal is known.

An Automated Open-Source Approach for Debinding Simulation in Metal Extrusion Additive Manufacturing

As an alternative to powder-bed based processes, metal parts can be additively manufactured by extrusion based additive manufacturing. In this process, a highly filled polymer filament is deposited and subsequently debindered and sintered. Choosing a proper orientation of the part that satisfies the requirements of the debinding and sintering processes is crucial for a successful manufacturing process. To determine the optimal orientation for debinding, first, the part must be scaled in order to compensate the sinter induced shrinkage. Then, a finite element analysis is performed to verify that the maximum stresses due to the dead load do not exceed the critical stress limits. To ease this selection process, an approach based on open source software is shown in this article to efficiently determine a part’s optimal orientation during debinding. This automates scaling, debinding simulation, and postprocessing for all six main directions. The presented automated simulation framework is examined on three application examples and provides plausible results in a technical context for all example parts, leading to more robust part designs and a reduction of experimental trial and error. Therefore, the presented framework is a useful tool in the product development process for metal extrusion additive manufacturing applications.

ALGORITHM FOR DETERMINING THE BOUNDARIES OF THE ZONE OF INTERFERENCE OPERATION OF THE RADIO CHANNEL OF THE UHF / VHF RANGE COMMUNICATION IN THE CONDITIONS OF OPERATION OF THE RADIOSHENOPRIAD SOURCE SYSTEM AT DIFFERENT HEIGHTS

A method for determining the limits of the maximum size of the stable radio reception area in the UHF / VHF range for mobile radio communication under the conditions of the radio interference system is proposed. The radio is intended to use a directional antenna or screen. Increasing the size of the stable radio reception area is provided by the optimal orientation at each point of the antenna device in azimuth and angle using the model of the radio channel, which allows to calculate the signal / interference ratio taking into account the spatial location of radio interference sources and digital 3D antenna pattern. receiver. The problem of determining the boundaries of the zone of stable radio exchange of mobile radio means using directional antennas in the conditions of real interference is formulated in the form of the problem of finding a single isoline in a scalar field. To determine the coordinates of the points of the map belonging to the isoline, a modification of the wave algorithm is proposed, which is low complexity and unambiguous results. Examples of practical use of the proposed numerical method allow us to conclude that the results are inconsistent with the data obtained in the known works by the analytical method for a particular case. At the same time, the numerical approach used significantly expands the possibilities of calculations by taking into account the location of multiple sources of radio interference at different altitudes, as well as the optimal orientation of the digital 3D - pattern of the antenna device of the signal receiver. The effectiveness of the proposed method is confirmed by increasing the area of the noise-tolerant radio exchange zone by 2.8 times in relation to the option of using a mobile radio with a dipole antenna. For the case of optimal orientation of the directional antenna of the receiver by the azimuth angle, additional optimization by the angle of the place gives a gain of 1.5 times.

A new method to determine the optimal orientation of Slim Modiolar cochlear implant electrode array insertion

Our goal was to determine the optimal orientation of insertion of the Slim Modiolar electrode and develop an easy-to-use method to aid implantation surgery. In some instances, the electrode arrays cannot be inserted in their full length. This can lead to buckling, interscalar dislocation or tip fold-over. In our opinion, one of the possible reasons of tip fold-over is unfavourable orientation of the electrode array. Our goal was to determine the optimal orientation of the Slim Modiolar electrode array relative to clear surgical landmarks and present our method in one specified case. For the measurement, we used the preoperative CT scan of one of our cochlear implant patients. These images were processed by an open source and free image visualization software: 3D Slicer. In the first step we marked the tip of the incus short process and then created the cochlear view. On this view we drew two straight lines: the first line represented the insertion guide of the cochlear implant and the second line was the orientation marker (winglet). We determined the angle enclosed by winglet and the line between the tip of the incus short process and the cross-section of previously created two lines. For the calculation we used a self-made python code. The result of our algorithm for the angle was 46.6055°. To validate this result, we segmented, from the CT scan, the auditory ossicles and the membranaceous labyrinth. From this segmentation we generated a 3D reconstruction. On the 3D view, we can see the position of the previous lines relative to the anatomical structures. After this we rotated the 3D model together with the lines so that the insertion guide forms a dot. In this view, the angle was measured with ImageJ and the result was 46.599°. We found that our method is easy, fast, and time-efficient. The surgery can be planned individually for each patient, based on their routine preoperative CT scan of the temporal bone, and the implantation procedure can be made safer. In the future we plan to use this method for all cochlear implantation surgeries, where the Slim Modiolar electrode is used.

Research on the influence of workpiece orientation during processing in disc centrifugal machine on the geometrical structure of its surface and processing efficiency

The article describes the result of experiments witch were intended to compare the results of different workpieces orientation in disc centrifugal machine. During experimental investigations, particular attention was paid to the optimal orientation the workpiece in working charge. The results of the research presented in this article confirm the benefit of horizontal orientation of the workpiece to the motion of the media in the working charge.