Transcatheter valve replacement often saves patients’ lives. The procedure has become relatively safe and very effective, and may soon become common practice.

Most studies on solenoid valves (SVs) assumed that the armature is concentrically positioned in the sleeve. Under this assumption the transversal component of the magnetic force is equal zero. The article presents an analytical calculation model for the estimation of the armature eccentricity. Using this model the eccentricity was calculated as a function of the sleeve thickness and the hydraulic clearance between the armature and the sleeve. After finding the eccentricity also the permeance of the radial air gap was calculated. This permeance has a direct influence on the drop of the magnetomotive force in the magnetic circuit and finally influences also the axial component of the magnetic force. In the article a calculation of both transversal and axial components of the magnetic force was carried out and presented in the appendix to the article.

Aortic stenosis is the most common acquired valvular heart disease. Aortic stenosis has growing prevalence in people older than 75 years and natural course of disease is characterized by high mortality rate. According to epidemiological data all patients with aortic stenosis will die after 2–5 years from the first signs of disease if not undergo aortic valve replacement. However, even 40% of patients do not have surgery because of comorbidities related to advanced age. This was the main reason why in 80- and 90-ties of XX century there were intensive attempt to developed an alternative, less invasive treatment methodology for people with aortic stenosis and comorbidities and at high surgical risk. Transcatheter aortic valve implantation (TAVI) was introduced by Dr Alain Cribier in February 2nd, 2002 in Rouen, France. Since that day different aortic transcatheter bioprostheses were used in many randomized clinical trials comparing their safety and effectiveness versus surgical aortic valve replacement. Gradually, it became clear that in all older patients in all risk groups TAVI was equally or even more safe and effective than surgery. Complications after TAVI are relatively rare, but some of them are life-threatening. Heart Team plays a key role in patients selection to TAVI.

Introduction: Seasonal variation has been observed for bacterial and viral infections (e.g., COVID-19 [1]), but also for numerous cardiac problems. However, little information is available on the seasonality of infectious endocarditis (IE), a rare disease that is usually linked to a bacterial origin. Data from the Polish population are lacking.
Materials and Methods: Our retrospective study focused on the identification of patients with IE, who were hospitalized at the University Hospital in Krakow between 2005–2022. For this purpose, we searched the medical records system using the ICD-10 code. We decided to divide our patients into four groups (winter, spring, summer, autumn), based on the date of admission to the hospital. Comparison of the distribution of IE incidents by season was performed with the ch2 test.
Results: One hundred and ten patients were included in the study (median age 62.5 years (range 20–94), 72 men (65.45%)). The left native valve IE was diagnosed in 49% of the patients, the prosthetic valve IE in 16%, the right valve IE in 27% and the implantable cardiac electronic devices IE in 12% of the subjects. The outcomes comprised of cardiac surgery (n = 53), embolism (n = 16), death (n = 15) and metastatic infections (n = 5). No differences in the incidence of IE by season were observed.
Conclusions: In the preliminary observation of IE cases of patients admitted to the University Hospital in Krakow, Poland no seasonal pattern of IE was detected. Therefore, IE should be taken into account in the differential diagnosis at any time of the year.

In order for the working status of the aluminum alloyed hydraulic valve body to be controlled in actual conditions, a new friction and wear

design device was designed for the cast iron and aluminum alloyed valve bodies comparison under the same conditions. The results

displayed that: (1) The oil leakage of the aluminum alloyed hydraulic valve body was higher than the corresponding oil leakage of the iron

body during the initial running stage. Besides during a later running stage, the oil leakage of the aluminum alloyed body was lower than

corresponding oil leakage of the iron body; (2) The actual oil leakage of different materials consisted of two parts: the foundation leakage

that was the leakage of the valve without wear and wear leakage that was caused by the worn valve body; (3) The aluminum alloyed valve

could rely on the dust filling furrow and melting mechanism that led the body surface to retain dynamic balance, resulting in the valve

leakage preservation at a low level. The aluminum alloy modified valve body can meet the requirements of hydraulic leakage under

pressure, possibly constituting this alloy suitable for hydraulic valve body manufacturing.

In order to study the effects of various gating systems on the casting of a complex aluminum alloyed multi-way valve body, both software simulation analysis and optimization were carried out. Following, the aluminum alloyed multi-way valve body was cast to check the pouring of the aluminum alloy valve body. The computer simulation results demonstrated that compared to the single side casting mode, the casting method of both sides of the gating system would reduce the filling of the external gas, while the air contact time would be lower. Adversely, due to the pouring on both sides, the melt cannot reach at the same time, leading to the liquid metal speed into the cavity to differ, which affected the liquid metal filling stability. The riser unreasonable setting led to the solidification time extension, resulting in a high amount of casting defects during solidification. Also, both gating systems led the entire casting inconsequential solidification. To overcome the latter problems, a straight gate was set at the middle pouring and the horizontal gate diversion occurred on both sides of pouring, which could provide better casting results for the aluminum alloyed multi-valve body.

The aim of this study was to design and test an adjustable hydro-pneumatic damper for cab suspension. The goal was to make a simple and cheap solution for a damper, which is intended to be placed between the hydraulic cylinder and accumulator. Damping behaviour of different terrain types had to be taken into consideration. Terrain type varies from field to road driving and damping should react rapidly to varying conditions.

In this study, the semi-active damper has been built with a hydraulic direct acting cartridge type 2/2-way proportional flow control valve. Flow-pressure curves and dynamic tests were carried out in the laboratory. The dynamic test with forced vibration focused on stability in damping frequencies and step response between different states. Also, total damping force was measured in different damping states and the proportional valve’s precise step responses and stability were investigated in a closed hydraulic system.

As a result, this research gave a lot of new information about the proportional valve’s applicability to work as a semi-active damper and information about damping behaviour. Research showed that a proportional valve can work in a cab suspension damper as well as a multi-fixed orifice damper. Bi-directional flow in the proportional valve was found to remain stable in cab suspension working conditions. The proportional valve also has the ability to work as a continuous state damper, which could lead to better damping results with the appropriate control system.

The pump performance and occurrence of cavitation directly depends on different operating conditions. To cover a wide range of operation conditions for detecting cavitation in this work, investigations on the effect of various suction valve openings on cavitation in the pump were carried out. In order to analyse various levels of cavitation in different operation conditions, the effect of the decrease in the inlet suction pressure of the centrifugal pump by controlling the inlet suction valve opening was investigated using this experimental setup. Hence, the acoustic and pressure signals under different inlet valve openings and different flow rates, namely, 103, 200, 302 l/min were collected for this purpose. A detailed analysis of the results obtained from the acoustic signal was carried out to predict cavitation in the pump under different operating conditions. Also, the acoustic signal was investigated in time domain through the use of the same statistical features. The FFT technique was used to analyse the acoustic signal in the frequency domain. In addition, in this work an attempt was made to find a relationship between the cavitation and noise characteristics using the acoustic technique for identifying cavitation within a pump.

The presence of noises in the vehicle cabin is an annoyance phenomenon which is significantly affected by the heating, ventilation, and air conditioning (HVAC) system. There are very limited studies reported on the specific type of noise characterisation and validation for both model and vehicle system levels. The present study developed a model of HVAC system that reflects the operation as in real vehicle, and the investigation of the HVAC components were carried out individually to determine which component contributes to the humming-type noise and vibration. The study was conducted under two conditions; idle speed of engine (850 rpm) and operating condition (850–1400 rpm). A ixed blower speed and fullface setting were applied throughout the experimental process. Three different sensors were used for the experiment, which are: accelerometer, tachometer, and microphone. From the results, the compressor and AC pipe components have contributed the most in generating the noise and vibration for both the model and vehicle systems. The findings also highlight that the humming-type noise and vibration were produced in the same operating frequency of 300–400 Hz and 100–300 Hz for idle and operating conditions, respectively, and this result was validated for both model and vehicle system levels.

Heating, ventilation and air conditional (HVAC) system provides a cold ventilation for the comfort of the driver and passengers in a vehicle. However, the vibration induced by the HVAC contributes to a reasonable level of noise emission, and hissing is one of the critical noises. So far, the characterization of hissing noise from the vehicle is least to be reported compared to other type of noises. Hence, this paper investigates the occurrence of hissing noise from several HVAC components. A lab-scale HVAC system was developed to imitate the real-time operations of the vehicle HVAC system. Two engine conditions, namely as ambient and operating conditions, were tested at speed of 850 rpm and 850–1400 rpm, with the blower speed maintained constantly at one level. The result shows that the hissing noise from the labscale HVAC was produced at frequency range of 4000–6000 Hz. The finding also highlights that the main component contributors of noise emission are an evaporator and a thermal expansion valve. The validation with a real vehicle system showed a good consensus whereby the hissing noise was produced at the similar operating frequency ranges. Also, the hissing noise was found to be louder when in an operating condition which could be taken into consideration by the vehicle manufacturers to improve the HVAC design.

The study discusses the issues of low durability of dies used in the first operation of producing a valve type forging from high nickel steel assigned for the application in motor truck engines. The analyzed process of manufacturing the exhaust valve forgings is realized in the coextrusion technology, followed by forging in closed dies. This process is difficult to master, mainly due to elevated adhesion of the charge material (high nickel steel – NCF3015) to the tool substrate as well as very high abrasive wear of the tool, most probably caused by the dissolution of hard carbide precipitates during the charge heating. A big temperature scatter of the charge during the heating and its short presence in the inductor prevents microstructure homogenization of the bearing roller and dissolution of hard precipitates. In effect, this causes an increase of the forging force and the pressures in the contact, which, in extreme cases, is the cause of the blocking of the forging already at the beginning of the process. In order to analyze this issue, complex investigations were conducted, which included: numerical modelling, dilatometric tests and hardness measurements. The microstructure examinations after the heating process pointed to lack of structure repeatability; the dilatometric tests determined the phase transformations, and the FEM results enabled an analysis of the process for different charge hardness values. On the basis of the conducted analyzes, it was found that the batch material heating process was not repeatable, because the collected samples showed a different amount of dissolved carbides in the microstructure, which translated into different hardnesses (from over 300 HV to 192 HV). Also, the results of numerical modeling showed that lower charge temperature translates into greater forces (by about 100 kN) and normal stresses (1000 MPa for the nominal process and 1500 MPa for a harder charge) and equivalent stresses in the tools (respectively: 1300 MPa and over 1800 MPa), as well as abrasive wear (3000 MPa mm; 4500 MPa mm). The obtained results determined the directions of further studies aiming at improvement of the production process and thus increase of tool durability.

More than 4.6 mln ha in the Russian Federation are irrigated. Their culvert hydraulic structures are part of network structures and are the most widespread. After the crisis of the 1990s, proper maintenance of many reclamation systems was impossible due to a lack of funds. This led to the loss of about half of the water taken from irrigation sources in irrigation canals. The planned increase in the technical level of irrigation systems requires the automation of the operation of both the entire system as a whole and separately located culverts. This will avoid significant losses of water supply for irrigation and prevent water shortages with the insufficient discipline of water users. Means of hydraulic automation of water supply are being installed on small irrigation canals in Russia. A water flow regulating valve is proposed, with no mechanical movinparts, and gates are not involved in the control process. The operation of the structure is based on the injection effect, in which excess water entering the downstream with a decrease in water consumption begins to circulate between the outlet section of the transit pipe and the diffuser at the end section of the valve. Using the methods of measuring hydrodynamics and the theory of jet devices, theoretical dependences were obtained, which make it possible to determine the main hydraulic characteristics of the structure. The design form of the flow part of the regulator has been developed and a physical model has been made. In a mirror hydraulic flume, the operation modes of the water outlet were studied with and without regulation. The actual values of hydraulic parameters were obtained, which confirmed the validity of the use of theoretical dependencies. The discrepancy between the theoretical and experimental results is within the experimental error. It has been proven that it is possible to circulate excess water between the downstream and intermediate pools of the regulator.

On the basis of mathematical modeling of fluid flow in vortex devices verification of use of detached-eddy simulation method in the swirling flows in vortex chamber superchargers is made. Research of a flow with use of different turbulence models was made for vortex chamber supercharger in two working points of the characteristic: with the open exit channel and closed. Verification has been spent on integrated parameters, and also on kinematic, by comparison of static pressure value of on the top end cover of the device. It is received that the hybrid turbulence model DES does not allow, as well as model SST precisely to predict value of vacuum on an axis of the vortex chamber. The error makes an order of 20 %. However, DES predicts almost correct, on 20 % big, than model SST, values of vacuum on an axis in a throat axial diffuser on an input in the vortex chamber. Besides, by means of DES it is possible to describe more adequately unsteady structures near to an axis of the vortex chamber, and also vortex core precession that does not allow to make SST turbulence model. By optimization of vortex devices, and vortex chamber superchargers in particular, simulation time essentially is better to use SST turbulence model with rotation-curvature correction.

The theoretical analysis of the charge exchange process in a spark ignition engine has been presented. This process has significant impact on the effectiveness of engine operation because it is related to the necessity of overcoming the flow resistance, followed by the necessity of doing a work, so-called the charge exchange work. The flow resistance caused by the throttling valve is especially high during the part load operation. The open Atkinson-Miller cycle has been assumed as a model of processes taking place in the engine. Using fully variable inlet valve timing the A-M cycle can be realized according to two systems: system with late inlet valve closing and system with early inlet valve closing. The systems have been analysed individually and comparatively with the open Seiliger-Sabathe cycle which is a theoretical cycle for the classical throttle governing of the engine load. Benefits resulting from application of the systems with independent inlet valve control have been assessed on the basis of the selected parameters: fuel dose, cycle work, charge exchange work and a cycle efficiency. The use of the analysed systems to governing of the SI engine load will enable to eliminate a throttling valve from the system inlet and reduce the charge exchange work, especially within the range of part load operation.

Department of Electrical Engineering, Anna University Regional Centre, Coimbatore, India This paper presents a new approach to solve economic load dispatch (ELD) problem in thermal units with non-convex cost functions using differential evolution technique (DE). In practical ELD problem, the fuel cost function is highly non linear due to inclusion of real time constraints such as valve point loading, prohibited operating zones and network transmission losses. This makes the traditional methods fail in finding the optimum solution. The DE algorithm is an evolutionary algorithm with less stochastic approach to problem solving than classical evolutionary algorithms.DE have the potential of simple in structure, fast convergence property and quality of solution. This paper presents a combination of DE and variable neighborhood search (VNS) to improve the quality of solution and convergence speed. Differential evolution (DE) is first introduced to find the locality of the solution, and then VNS is applied to tune the solution. To validate the DE-VNS method, it is applied to four test systems with non-smooth cost functions. The effectiveness of the DE-VNS over other techniques is shown in general.

In humans, iron deficiency represents a relevant occurrence in heart failure (HF), with or without anaemia, and is associated with the worst outcome. Moreover, chronic kidney disease (CKD) is a well-known comorbidity of HF and is strongly associated with the risk of developing anaemia. The most common cause of HF in dogs is myxomatous mitral valve disease (MMVD). To the best of our knowledge, no studies have examined the iron status in dogs with HF, with and without CKD. The aim of this retrospective study was to evaluate the iron status in dogs affected by MMVD and how strong is the relation with HF.

The retrospective study included 54 dogs with complete case records, echocardiography and laboratory analyses. Iron status was evaluated by measuring serum iron concentration (SIC), un- saturated iron binding capacity (UIBC), total iron binding capacity (TIBC), and percentage of saturation (%SAT).

The prevalence of dogs showing low serum iron concentration (SIC) was 18% in the whole population, 33% in symptomatic patients, 100% in dogs with acute decompensated HF. No signif- icant differences in SIC, UIBC, TIBC and %SAT median values were found among dogs classi- fied in different ACVIM (American College of Veterinary Internal Medicine) classes, between symptomatic and non-symptomatic patients, and among IRIS (International Renal Interest Soci- ety) classes. Azotemic and non-azotemic patients presented a significant difference in SIC mean values (p=0.02). Generalised linear model (GLM) revealed that dogs with low SIC were at high- er risk of being included in a higher ACVIM class (OR=6.383, p-value=0.014).

Log-rank analysis showed shorter survival in dogs with low SIC (p=0.020), multivariate Cox analysis revealed that only HF symptoms can affect survival.

The study presents a durability analysis of dies used in the first operation of producing a valve-type forging from high nickel steel assigned to be applied in motor truck engines. The analyzed process of producing exhaust valves is realized in the forward extrusion technology and next through forging in closed dies. It is difficult to master, mainly due to the increased adhesion of the charge material (high nickel steel) to the tool’s substrate. The mean durability of tools made of tool steel W360, subjected to thermal treatment and nitriding, equals about 1000 forgings. In order to perform a thorough analysis, complex investigations were carried out, which included: a macroscopic analysis combined with laser scanning, numerical modelling by FEM, microstructural tests on a scanning electron microscopy and light microscopy (metallographic), as well as hardness tests. The preliminary results showed the presence of traces of abrasive wear, fatigue cracks as well as traces of adhesive wear and plastic deformation on the surface of the dies. Also, the effect of the forging material being stuck to the tool surface was observed, caused by the excessive friction in the forging’s contact with the tool and the presence of intermetallic phases in the nickel-chromium steel. The obtained results demonstrated numerous tool cracks, excessive friction, especially in the area of sectional reduction, as well as sticking of the forging material, which, with insufficient control of the tribological conditions, may be the cause of premature wear of the dies.

A mathematical model, created for description of the mechanism of interaction between basic parameters of high pressure dispersion of emulsions, is presented in this paper. The model is applied for the analysis of the influence of physical properties of emulsions, quantitative content of dispersed emulsion phase and parameters of emulsification, pressure and temperature, on the characteristic dimension of particles of the dispersed phase. The model makes it possible to determine appropriate process parameters, especially the pressure necessary to obtain the required dispersion of the emulsion and to define construction and exploitation parameters of high-pressure emulsification valve.

Hydroacoustic projectors are useful for generating low frequency sounds in water. Existing works on hydroacoustic projectors require two significant enhancements, especially for designers. First, we need to understand the influence of important projector design parameters on its performance. Such insights can be very useful in developing a compact and efficient projector. Second, there is a need for an integrated model of the projector based on easily available and user-friendly numerical tools which do not require development of complex customised mathematical analogs of projector components. The present work addresses both such needs. Towards these goals, an experimentally validated, easy-to-build projector model was developed and used to conduct design sensitivity studies. We show that reductions in pipe compliance and air content in oil, and an increase in orifice discharge coefficient can yield remarkable improvements in projector’s SPL. We also show that reductions in pipe length and cylinder diameter cause moderate improvements in performance in mass and stiffness controlled regions, respectively. In contrast, the projector performance is insensitive to changes in pistonic mass, cylinder length, and diaphragm stiffness. Finally, we report that while pipe compliance and air content in oil can sharply alter system resonance, the effects of changes in pipe length and pistonic mass on it are moderate in nature.

Commutation reactance is an important component in the voltage-source converter- based high-voltage direct current (VSC–HVDC) transmission system. Due to its connection to the converter, when there is a fault occurring on the valve-side bushing of a converter transformer, the nonlinearity operation of the converter complicates the characteristics of current flowing through commutation reactance, which may lead to maloperation of its overcurrent protection. It is of great significance to study the performance of commutation reactance overcurrent protection under this fault condition and propose corresponding improvement measures to ensure the safe and stable operation of AC and DC systems. In the VSC–HVDC system with the pseudo-bipolar structure of a three-phase two-level voltage source converter, the valve has six working periods in a power frequency cycle, and each period is divided into five working states. According to the difference between the fault phase and non-fault phase of the conductive bridge arms at the time of fault occurrence, these five working states are merged into two categories. On this basis, various faults of the valve-side bushing of a converter transformer are analyzed, and the conclusion is drawn that the asymmetric fault of valve-side bushing can lead to the maloperation of the commutation reactance overcurrent protection. Based on the characteristics that the current flowing through the commutation reactance after the asymmetric fault of the valve-side bushing contains decaying aperiodic components in addition to the fundamental frequency wave, a scheme to prevent the maloperation of commutation reactance overcurrent protection is proposed, which uses the unequal of two half cycle integral values with different starting points to realize the blocking of commutation reactance overcurrent protection, and it makes up the deficiency of existing protection in this aspect. Finally, this paper builds a VSC–HVDC system simulation model in the PSCAD/EMTDC platform to verify the effectiveness of the scheme.

This paper investigated the problems and impacts of transient flow in pipeline systems due to pump power failure. The impact of different protection devices was presented to assure surge protection for the pipeline system. A model via Bent-ley HAMMER V8.0 Edition was employed to analyse and simulate hydraulic transients in the pipeline system, and protec-tion alternatives were studied.

Surge protection included using only an air vessel, using an air vessel and two surge tanks, and employing five air ves-sels and vacuum breaker. The obtained results for pressures, heads, and cavitation along the pipeline system were graph-ically presented for various operating conditions. Using five air vessels with vacuum breaker valve as surge protection proved to be more effective and economical against pump power failure.

Changing the flow density did not have a significant impact on the pressures.

For protection with an air vessel; it was concluded that the value 40% of the original diameter for inlet pipe diameter of air vessel, and the value of 2/3 of original pipe diameter were critical values for the transient pressures. Cast iron pipes proved to be the best pipe material for all studied volumes of the air vessel.

For protection with an air vessel and two surge tanks; as the inlet pipe diameters increased the maximum pressures in-creased and the minimum pressures decreased.

Regression analyses were performed obtaining equations to predict the pressures according to the inlet pipe diameter, the area of surge tank, and the pipe diameter.