VIBRATIONS OF THE BICARDANIC TRANSMISSIONS WITH

In order to study the lateral vibrations of the policardanic transmissions, they assimilate with theelastic systems of bars articulated between them and suspended by elastic cantilivers, the bars having in theircomponent different sections.In this paper some bases of computation for own pulsations are elaborated andnumerical calculations are performed for this purpose

On the electrostatic inertia in microgrids with inverter-based generation only—an analysis on dynamic stability

Storage4Grid project grant agreement No. 731155 RESERVE project grant agreement No. 727481 KIOS CoE grant agreement No. 739551.Microgrids are about to change the architecture and the operation principles of the future power systems towards smartness and resiliency. Power electronics technologies are key enablers for novel solutions. In this paper we analyze the benefits of a “microgrid by design” architecture (MDA), using a solid-state transformer (SST) as a low-voltage grid-former and inverter-based generation only. In this context, the microgrid stability is maintained with the help of “electrostatic energy inertia” that can be provided by the capacitor connected to the DC busbar behind the SST inverter topology. This happens in a natural way, alike the mechanical inertia in power systems with synchronous machines, however without depending on frequency and without the need of a rotational inertia. This type of microgrid always operates (both fully connected to the main grid or in islanding mode) with all the necessary mechanisms needed to maintain the microgrid stable—no matter of the perturbations in the upstream of the point of common coupling (PCC). In the case of microgrids with inverter-based generation only (including the energy storage systems), there is no mechanical inertia and different stability mechanisms need to be applied compared to the stability principle of the classical power systems. Our proposed mechanism differentiates from the recently proposed stability assessments of microgrids based on virtual synchronous generators from the control theory perspective. This paper is a continuation of our previous work where the MDA was first introduced. The use-cases and scenarios are based on realistic and yet reasonable complexities, by coupling the disturbance magnitude with the voltage stability limit in power grids. The paper finds meaningful disturbances to test the electrostatic energy inertia at the boundaries of grid stability, as guidance to understand the range of voltage variation for extreme conditions. The results show that in microgrids with inverter-based generation only and passive loads (RLC type) the operation is no longer frequency dependent. The energy of the DC busbar capacitor as electrostatic energy inertia of the MDA has a role similar to that of the rotational machines in classical grids in terms of maintaining dynamic stability, however impacting two different types of stability.publishe

Manifesto on small airway involvement and management in asthma and chronic obstructive pulmonary disease:an Interasma (Global Asthma Association - GAA) and World Allergy Organization (WAO) document endorsed by Allergic Rhinitis and its Impact on Asthma (ARIA) and Global Allergy and Asthma European Network (GA2LEN)

Evidence that enables us to identify, assess, and access the small airways in asthma and chronic obstructive pulmonary disease (COPD) has led INTERASMA (Global Asthma Association) and WAO to take a position on the role of the small airways in these diseases. Starting from an extensive literature review, both organizations developed, discussed, and approved the manifesto, which was subsequently approved and endorsed by the chairs of ARIA and GA2LEN. The manifesto describes the evidence gathered to date and defines and proposes issues on small airway involvement and management in asthma and COPD with the aim of challenging assumptions, fostering commitment, and bringing about change. The small airways (defined as those with an internal diameter <2 mm) are involved in the pathogenesis of asthma and COPD and are the major determinant of airflow obstruction in these diseases. Various tests are available for the assessment of the small airways, and their results must be integrated to confirm a diagnosis of small airway dysfunction. In asthma and COPD, the small airways play a key role in attempts to achieve disease control and better outcomes. Small-particle inhaled formulations (defined as those that, owing to their size [usually <2 μm], ensure more extensive deposition in the lung periphery than large molecules) have proved beneficial in patients with asthma and COPD, especially those in whom small airway involvement is predominant. Functional and biological tools capable of accurately assessing the lung periphery and more intensive use of currently available tools are necessary. In patients with suspected COPD or asthma, small airway involvement must be assessed using currently available tools. In patients with subotpimal disease control and/or functional or biological signs of disease activity, the role of small airway involvement should be assessed and treatment tailored. Therefore, the choice between large- and small-particle inhaled formulations must reflect the physician’s considerations of disease features, phenotype, and response to previous therapy. This article is being co-published in Asthma Research and Practice and the World Allergy Organization Journal

THE INFLUENCE OF THE CONSTRUCTIVE PARAMETERS ON THE VIBRATION INHERENT FREQUENCIES AT BENDING FROM TWOSHAFTS TRANSMISSION

The shafts transmissions that can be treated as the elastic linkage systems of various sections, length and specific weights, suspended on elastic supports. The average fiber elastic deforms under the action of own weight static, generating a mass eccentric to the axis of rotation of its own.The eccentric mass during the even rotation produces a centrifugal force, which increases the elastic deformation leading to the occurrence of bending vibration. The own pulses of this vibrations depend on the mechanic and constructiv caracteristic of the cardan transmissions. This paper presents the influence these characteristic over the frequencies and vibration modes inherent at bending and based on numerical simulations will draw conclusion

MATHEMATICAL MODEL FOR DETERMINING THE EFFORTS FROM CARDAN JOINT MECHANISM WITHOUT TECHNICAL DEVIATIONS

The cardan joint mechanism enables the transmission of the rotation movement between two shaft trees which form a constant or variable angle in time. This the mechanism is of the third family , as a consequence, multiple statically indeterminate and for calculating the reactions from the kinematic pairs it is applied the elastic linear calculation using the relative displacements method noted in plücker coordinates. In this paper are deducted the calculation relations and is established the mathematical model for determining the efforts of the ideal (without technical deviations) cardan joint The mechanism, starting from the RRRR spatial quadrilateral mechanism.The results of the numerical solving of this problem will be presented under the form of a diagram and will be commented

THE NUMERICAL STUDY OF EFFORTS FROM A 4R SPHERICAL QUADRILATERAL MECHANISM

Abstract—The 4R spherical quadrilateral mechanism, where by R is notated the rotation cinematic couple, from which is obtained the cardan mechanism, is of third family, as consequence, triple static undetermined and for calculating the reactions from the cinematic couples it is applied the elastic linear calculation using the relative displacements method noted in plukerian coordinates. By using this method and numerical calculation, allows one to determine the reactions from the cinematic couples, as the method can be applied to different types of spatial or plane mechanisms. The calculation algorithm established in this paper and the program that was made, allows the user to determine the influence of mechanical and geometrical characteristics each element of the spherical 4R mechanism over the reactions from its cinematic couples. The results of the numerical solving of this problem will be presented under the form of a diagram and will be commented.

DETERMINATION OF THE VIBRATION INHERENT FREQUENCIES AT BENDING FROM TWO-SHAFTS TRANSMISSION IN THE PARTICULAR CONSTRUCTION CASES

- The exact determination of the critical speeds and the influence of the different constructive and mechanical factors on them can be done on the dynamic model with distributed mass.The characteristic equation for calculating vibration inherent frequencies at bending obtained on this model is transcendental and is usually solved by approximate methods. This model starts from an initial value of the pulse p to which, by successive approximations, it satisfies the characteristic equation attached to the cardan transmission.Starting from the particular constructive cases we can determine quite well the value p of initiation of the general mathematical model of calculating the own pulsations of vibration at bending

THE TECHNICAL AND GEOMETRICAL DEVIATIONS OF CARDAN JOINT MECHANISM

During the manufacturing and montage process of cardan transmissions, at the component elements may inevitable appear technical (geometrical) deviations. These deviations lead to the changine of kinematic parameters of the mechanism.For the determination of these changes it is first necessary to identify these deviations and give them a geometrical interpretation. By having as a purpose the identifying of both angular and axis deviations, over the kinematic parameters of the cardan joint mechanism, it is necessary to consider the cardan joint, not as a spherical quadrilateral but as a particular case of RCCC mechanism where by C, R was noted the cylindrical kinematic pair respectively the rotation kinematic pair

CALCULATION ALGORITHM FOR DETERMINING KINEMATIC PARAMETERS OF THE CARDAN JOINT MECHANISM WITH TECHNICAL (GEOMETRICAL) DEVIATIONS

The technological (geometrical) deviations of component elements of the cardan joint mechanism lead to the changine of kinematic parameters of the mechanism. For determining the influence of both angular and axis deviations, over the kinematic parameters of the cardan joint mechanism, it is necessary to consider the cardan joint, not as a spherical quadrilateral but as a particular case of RCCC mechanism where by C, R was noted the cylindrical kinematic pair respectively the rotation kinematic pair. In this paper is etablished the calculation algorithm for determining kinematic parameters of the cardan joint mechanism with technical (geometrical) deviations at component elements