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A high-quality, low-cost ventilator, dubbed HEV, has been developed by the particle physics community working together with biomedical engineers and physicians around the world. The HEV design is suitable for use both in and out of hospital intensive care units, provides a variety of modes and is capable of supporting spontaneous breathing and supplying oxygen-enriched air. An external air supply can be combined with the unit for use in situations where compressed air is not readily available. HEV supports remote training and post market surveillance via a Web interface and data logging to complement standard touch screen operation, making it suitable for a wide range of geographical deployment. The HEV design places emphasis on the ventilation performance, especially the quality and accuracy of the pressure curves, reactivity of the trigger, measurement of delivered volume and control of oxygen mixing, delivering a global performance which will be applicable to ventilator needs beyond the COVID-19 pandemic. This article describes the conceptual design and presents the prototype units together with a performance evaluation.

An analytical, numerical and experimental study is presented on the deagglomeration and dispersion of fine coal fly ash (CFA) reinforcing particles in an A380 aluminium matrix using a piston-actuated oscillating micro-grid mixing method with a specially designed grid geometry. Based on real-time measurement of the piston force, the apparent viscosity of the melt and the effectiveness of the deagglomeration are measured indirectly. The oscillating micro-grid mixing process is shown to be considerably more time-efficient that comparative stir-casting processes currently employed, leading to a two-fold or three-fold reduction in processing time for the same or better mixing quality, or alternatively a nearly two-fold reduction in the standard deviation of the micro-hardness throughout the material.

This article presents the design of a test device for cryogenic testing of concrete samples. Cryogenic tests consisted of compression and expansion tests of liquid nitrogen on cylindrical concrete specimens and their scope was to determine the linear coefficient of thermal expansion of the concrete material at temperatures from zero to minus 160° C. This article presents a design. Τhe test chamber and the new strategies that were used; along with the corresponding challenges posed by the heating and measurement problems. Affected heat transfer transient and steady state problems, which were realized using digital analysis using commercial FEM software, are presented along with the measurement equipment and methods that were used to match the numerically calculated temperature profiles along with the measured ones. In addition, the sample temperature measurement topology that was chosen for the experiments is compared with conventional ones in their ability to provide information representing the temperature state of the sample. Finally, the raw data from three tests are analyzed and the results are presented in appropriate graphs, taking into account the systematic errors introduced by thermal compression of the metrological equipment used for measuring length. The results are consistent with those available in the concrete literature.

The busbars for the HL-LHC magnets are made of Nb-Ti/Cu conductor, the insulation system, and the auxiliary equipment to align the busbars with respect to the magnet coldmasses. This paper presents design options concerning the integration of the busbars inside the coldmass with a fixed point, and a reinforced insulation system for the flexible busbar part using thin PEEK tubes. Prototype splices for interconnecting Nb3Sn and Nb-Ti Rutherford cables, and round and flat 18 kA Nb-Ti cable have been produced and first test results are presented.

Harmonic drives have been of significant importance in many industrial and high-end applications including robotics, aerospace and manufacturing. Their unique characteristics combine high torque capabilities, high to ultra-high transmission per stage and low backlash performance in compact designs, suited for limited space applications. However, apart from the eminent merits of the technology, this type of gearboxes is associated with complex dynamic performance. Since their operations is associated with high compliance and friction a non – linear behavior is imposed to the system. This is also intensified due to torque ripples which in many cases apart from adding up to the overall complexity of the system, can also interfere with components of similar resonance frequency. In the frame of this paper a novel concept for a low-cost lightweight plastic harmonic drive used in positioning of telecommunication antennas is presented. Due to the tight dynamic specifications of the application (settling time, positioning error etc.) the torque ripple of the transmission was modelled and minimized. Design changes were also incorporated in various features in order to improve the overall dynamic performance.

This paper presents an analysis of the contact and bending stresses of certain self-aligning automotive spur gear designs under various degrees of misalignment. The resulting deflection and stress fields are studied under quasi-static conditions and compared for different design variants. The proposed solution not only seems to eliminate the necessity to conduct gear tooth crowning, but also makes practical the increase of gear width and a corresponding reduction of the gear module, potentially further benefitting gear dynamics and efficiency.

Presented work aims to minimize the delivery fluctuation of a gear pump through geometrical optimisation of the tooth flank. Therefore, instead of examining various configurations, which would reduce the flow ripple ad hoc, the current study suggests the dependence the delivery fluctuation to the tooth flank profile. Taking into account the secondary derivative of the tooth profile, the optimisation process is able to also affect the secondary delivery fluctuation, which is connected to the compression of the fluid over the meshing cycle. Bezier-Bernstein polynomial curves were used to model the tooth flank in order to satisfy the objective function. A dependency between the total length of the path of contact curve and the flow ripple was found. It is stated in this work that for every design point on a closed path of gear set, there is a threshold on the contact length, over which the resulted flow ripple starts to deviate from the optimum value. That conclusion was used to further enhance the optimisation algorithm. The presented optimum gear profile design was evaluated through a comparative study between every design point and the corresponding solution of the existing state of the art in terms of delivery fluctuation.

In recent years multidisc wet friction clutches are of great importance to manufacturers of automatic transmissions (ATs) for the automotive industry, particularly since the introduction of double-clutched ATs. Their main advantage compared to their dry-friction counterparts is that they ensure smooth engagement, high reliability and long service life. Their progressive engagement due to the developed Couette flow between the discs enables them to be used both as clutches and as brakes in order to control power flow in simultaneously engaged geared shafts in the AT. Due to the coupled nature between the mechanical and the fluid dynamics regimes governing their operation, these systems are highly complex to be treated analytically and instead numerical approaches have proven to provide better results. However, the numerical treatment of such problems provides only case-specific results, which cannot be generalised and are not able to provide a general insight in the complex dynamics of the device. Furthermore the computational cost and the associated modelling and simulation effort during the design phase is high, making the incorporation of such methods in iterative design processes and algorithms counterproductive. In this paper the modelling of the dynamic behaviour of a wet multidisc clutch during the engagement phase is performed, via the combination of analytical and numerical methods and conclusions are drawn about the effect of the main geometric, kinematic and dynamic design parameters on the clutch’s response. The dynamic modelling is performed by applying the principle of linear and angular momentum on each disc. The effect of the fluid film is taken into account through the solution of the governing Navier-Stokes equations via CFD analysis or by the use of semi-analytical solutions with high accuracy, where applicable. Therefore both the developed pressure field and the torque of the fluid film are calculated efficiently and used in the simulation of the system. The flow is assumed to be laminar and the discs rigid and flat.

High-ratio compound stepped planetary transmissions are typically characterised by poor overall efficiencies, even if the individual mesh efficiencies are high, because of the very high sliding velocities imposed by the kinematics of their topologies. Here, a parametric exploration of the design space is presented for a stepped transmission topology, which is assessed in terms of transmission ratio, efficiency, and power density. It is confirmed that high ratio per (compound) stage is accompanied by low mechanical efficiency and/or large volume for the most part of the parametric design space, as is also anticipated by prior research. At the same time, specific niche regions of particular importance are identified that combine high-ratio, high-efficiency, and good power density.

This article proposes a new set of configurationsfor the construction of a low cost servo-actuatedshake table with a wide range simulation ability, especially regarding ground motions with strong vertical components up to 3.86g and 1.62m acceleration and stroke respectively. Designing decision and challenges faced during the process are also presented.