Nuclear Reactor Pressure Thermal Shock Simulation

The article describes a multistage modelling methodology proposed by the author for the modelling of emergency core cooling processes. The methodology is based on the best practice guidelines presented by the IAEA, it is applied to a specific scenario of emergency core cooling during a loss of coolant accident [1] with an effective break diameter of 20mm. A 3D thermohydraulic analysis was performed as the first step in the solution process, where the transient changes in the pressure, velocity and temperature fields within the reactor pressure vessel were studied [2]. The primary knowledge learned when processing the results of the first step, was the presence of an oscillating cold coolant stripe in close proximity to the pressure vessel wall. The next step in the methodology consisted of a threedimensional thermo-mechanical analysis of the reactor pressure vessel [3]. In this step, pressure thermal shock induced critical zones of mechanical loading were identified and the influence of the oscillatory character of the cold stripe on the pressure vessel was studied

Analysis of PTS fracture loading of NR RPV

The article describes a multistage modelling methodology proposed by the author for the modelling of emergency core cooling processes. The methodology is based on the best practice guidelines presented by the IAEA, it is applied to a specific scenario of emergency core cooling during a loss of coolant accident[1] with an effective break diameter of 20mm. A 3D thermohydraulic analysis was performed as the first step in the solution process, where the transient changes in the pressure, velocity and temperature fields within the reactor pressure vessel were studied [2]. The primary knowledge learned when processing the results of the first step, was the presence of an oscillating cold coolant stripe in close proximity to the pressure vessel wall. The next step in the methodology consisted of a three-dimensional thermo_x0002_mechanical analysis of the reactor pressure vessel [3]. In this step, pressure thermal shock induced critical zones of mechanical loading were identified and the influence of the oscillatory character of the cold stripe on the pressure vessel was studied. The last step of the methodology consisted of a fracture mechanics analysis of postulated defects during the pressure thermal shock. Acquired results from the final step shown, that the postulated defects’ sensitivity to the oscillatory nature of the cold stripe is highly dependent on the postulated defect’s orientation

PIEZOELECTRIC BEAM FINITE ELEMENT MODEL AND ITS REDUCTION TO STATE-SPACE MODEL

The paper deals with modeling and simulation of the connection of piezoelectric materials, FGM materials and LQR control, using state-space model, which is built by modal truncation MOR method. FEM equations of piezoelectric finite beam were implemented in FEM program MultiFEM written in Wolfram Language. Modal truncation MOR method, which uses results from modal analysis, is also implemented in program Wolfram Mathematica. Simple piezoelectric structure is analyzed in numerical experiments, where FEM results are compared with MOR results

MOR of Piezoelectric Beam FEM Model and its Control

This paper deals with the development of the FEM model of piezoelectric beam elements, where the piezoelectric layers are located on the outer surface of the beam core, which is made of functionally graded material. Subsequently, the FEM model created in this way is reduced by the so-called exact method, which is one of the MOR methods. Next MOR FEM equations are transformed into a state space model. Created state space model is connected to LQR controller and the reduced system is analysed. Developed FEM model, MOR technique, state space model and LQR control are implemented in FEM code MultiFEM

Vibration of the cantilever beam using a piezoelectric actuator.

This paper deals with experimental and finite element analysis of vibration of the aluminum beam excited by a piezoelectric thin film actuator. One beam's end was fix supported and vibration of the beam's free end was measured using laser displacement sensor. Finite element model of the beam with piezoelectric actuator was created and three types of analyses were performed: modal, transient and harmonic. Results from finite element analyses were compared with data from experimental measurements

Canagliflozin and renal outcomes in type 2 diabetes and nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to <90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], >300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

Selected Nature-Inspired Algorithms in Function of PM Synchronous Motor Cogging Torque Minimisation

Both permanent magnet brushless DC motors and permanent magnet synchronous motors have attracted wide attention and are increasingly used in industrial high-performance applications in recent years. Those motors are known for their good electrical, magnetic and performance characteristics, but there is one parameter known as cogging torque that has a negative influence on the performance characteristics of the motor. This pulsating torque is generated as a result of the interaction between the stator teeth and the permanent magnets. The minimisation of the ripple of this torque in those permanent magnet motors is of great importance and is generally achieved by a special motor design which in the design process involves a variety of many geometrical motor parameters. In this research work, a novel approach will be introduced where two different nature-inspired algorithms, such as genetic algorithm (GA) and cuckoo search (CS) algorithm are used as an optimisation tool, in which the defined equation for the maximum value of the cogging torque is applied as an objective function. Therefore, a proper mathematical presentation of the maximum value of the cogging torque for the analysed synchronous motor is developed and implemented in the research work. For a detailed analysis of the three different motor models, the initial motor and the two optimised motor models are modelled and analysed using a finite element method approach. The cogging torque is analytically and numerically calculated and the results for all the models are presented

Study of the performance characteristics of surface permanent magnet motor at various magnetization patterns

Purpose – In the present paper the influence of magnetization patterns of the rotor magnets on the performance characteristics for surface permanent magnet (SPM) motor is investigated. The objective is to show how the electromagnetic and electromechanical characteristics of this type of motor can be significantly changed by applying various magnetization patterns of permanent magnets placed on the rotor surface. Design/methodology/approach – At the beginning a survey of possible and most frequently used magnetization patterns for permanent magnet motors is presented. The research is focussed on the comparison of performance characteristics and is developed into three levels. It is started with a conventional SPM motor having segmented permanent magnets, and two magnetization patterns are considered: parallel and radial. Showing no significant difference of the motor performance at parallel and radial magnetization, for further investigation only radial magnetization, being more conventional, is considered. In the second step, the counterparts of SPM with two Halbach array configurations, under the constraint of fixed magnet volume, are studied. Finally, detailed comparative analyses of SPM at radial, Halbach 1 and Halbach 2 magnet patterns are presented. Advantages and drawbacks for suggested magnet configurations are discussed. Findings – It is presented how the magnetization pattern of the rotor permanent magnets can have a substantial impact on the SPM motor performance characteristics. From the analysis of magnetic field properties at various types of magnetization, it is observed that both shape and rates of the characteristics, for radial magnetization and Halbach 2 configuration, exhibit similar features. It is due to the fact that Halbach 2 array cancels magnetic flux above the permanent magnets, i.e. strengthens the magnetic field in the rotor, and enhances the coupling between the rotor and stator magnetic field. It is worth to emphasise, that due to less saturation of the magnetic core and lower iron loss at Halbach 1 and Halbach 2 magnetization, it is possible to increase armature current and consequently to increase the electromagnetic torque. This fact could be interesting for further research. Originality/value – The paper presents an original comparative analysis for performance characteristics of a surface permanent motor at various magnetization patterns. The novelty of the paper is seen in the introduction of two Halbach magnetization array for permanent magnets and improvement of the performance characteristics for the analysed motor