Effects of a Single Blade Incidence Angle Offset on Adjacent Blades in a Linear Cascade

The paper presents a numerical and experimental investigation of the effect of incindence angle offset in a two-dimensional section of a flat blade cascade in a high-speed wind tunnel. The aim of the current work is tp determine the aerodynamic excitation forces and approximation of the unsteady blade-loading function using a quasi-stationary approach. The numerical simulations were performed with an in-house finite-volume code built on the top of the OpenFOAM framework. The experimental data were acquired for regimes corresponding to the numerical setup. The comparison of the computational and experimental results is shown for the static pressure distributions on three blades and upstream and downstream of the cascade. The plot of the aerodynamic moments acting on all five blades shows that the adjacent blades are significantly influenced by the angular offset of the middle blade.

Resonant Motions of Dynamic Offshore Structures in Large Waves

In marine engineering, the dynamics of fixed offshore structures (for oil and gas production or for wind turbines) are normally found by modelling of the motion by a classical mass-spring damped system. On slender offshore structures, the loading due to waves is normally calculated by applying a force which consists of two parts: a linear “inertia/mass force” and a non-linear “drag force” that is proportional to the square of the velocity of the particles in the wave, multiplied by the direction of the wave particle motion. This is the so-called Morison load model. The loading function can be expanded in a Fourier series, and the drag force contribution exhibits higher order harmonic loading terms, potentially in resonance with the natural frequencies of the system. Currents are implemented as constant velocity terms in the loading function. The paper highlights the motion of structures due to non-linear resonant motion in an offshore environment with high wave intensity. It is shown that “burst”/“ringing” type motions could be triggered by the drag force during resonance situations.

Penguasaan 4 (Empat) Prasyarat Dasar Aritmatika untuk Meningkatkan Kemampuan Siswa Sekolah Dasar dalam Menyelesaikan Soal Matematika

The purpose of this study discusses how mastery of 4 (four) basic prerequisites of arithmetic which includes the ability to count, make Arithmetic / multiples, complement especially Nines and ten, and the concept of place values in numbers affect students' ability to solve math problems consisting of addition, subtraction, multiplication, and multiplication. The approach in this study uses a descriptive approach, the method used is a combination of qualitative and quantitative methods. A qualitative approach is used to describe the basic arithmetic mastery of students including numeracy, making Arithmetic / multiples numbers, complements especially nines and ten, and the concept of place values in numbers. The quantitative approach uses statistical tests with canonical correlation analysis to answer the relationship and influence between understanding of basic arithmetic mastery on the ability to solve math problems related to addition, subtraction, multiplication and division. From the results of the canonical weight and canonical loading function 1, it can be concluded that there is indeed a significant relationship between the dependent variate and the independent variate or basic arithmetic mastery and the students' ability to do math problems is indeed correlated together.

Experiences of specialist social workers for asylum seeking patients at a large Swedish hospital

Background In 2016, the Karolinska University Hospital introduced a one-year-project with a mobile team of five asylum social workers (ASW), specializing in migration. This study evaluates the ordinary hospital social workers (HSW) experiences of introducing ASWs for asylum seeking patients. Methods Descriptive analysis was made of answers from a questionnaire sent to all 144 HSW at the hospital (57% response rate). Qualitative content analysis was made of written comments. Results Of the HSWs, 51% always and 29% sometimes contacted an ASW in relation to asylum seeking patients. Of those who contacted an ASW, 74% stated that the ASWs increased the efficiency of care of asylum seeking patients. 65% agreed that ASWs had an improving effect on the quality of encounters between staff and asylum seekers. Also, 67% agreed that the ASWs off-loading function improved the HSWs working conditions. Even though the ASWs were working at two hospitals located in different parts of the region, 78% of HSWs found them to be available. The main reason to not always contact an ASW was that it was not necessary in the specific case (55%). A majority (66%) reported increased knowledge about asylum processes as an outcome of introducing the ASWs at the hospital. This was also highlighted in the written comments, where ASWs detailed and updated knowledge as well as established contacts with e.g. the Swedish Migration Board was emphasized. ASWs specialist competence enabled patients to quickly receive legally correct and accurate information, which decreased worries among patients as well as staff members. Conclusions The HSWs described the ASWs as being important to patients as well as to staff. The ASWs improved the quality of encounters between staff and asylum seekers and strengthened the patient’s right to health and social care. The HSWs also reported an off-loading function, improving the working conditions and the over-all efficiency of care. Key messages The HSWs found that the ASWs increased the efficiency of care and quality of encounters between staff and asylum seekers. ASWs detailed knowledge and established external contacts enabled patient to receive accurate information quickly, which decreased worries among both patients and staff members.

Methodology for Searching Representative Elements

Companies have to assure their share on the global market, meet customer demands and produce customer-tailored products. With time and production line updates, the layout becomes non-optimal and product diversity only increases this problem. To stay competitive, they need to increase their productivity and eliminate waste. Due to a variety of products consisting of similar components and variants thereof, a huge number of various elements are encountered in a production process, the material flow of which is hardly manageable. Although the elements differ from each other, their representative elements can be defined. This paper will illustrate a methodology for searching representative elements (MIRE), which is a combination of the known Pareto’s analysis (also known as ABC analysis or 20/80 rule) and a calculation of a loading function, that can be based on any element feature. Results of using the MIRE methodology in a case from an industrial environment have shown that the analysis can be carried out within a very short time and this provides for permanent analysis, optimisation and, consequently, permanent improvement in the material flow through a production process. The methodology is most suitable for smaller companies as it enables rapid analysis, especially in cases when there is no pre-recorded material flow.

Analysis of the influence of train load characteristics on the water damage of slab tracks

High-speed train load is one of the main factors that causes the failure of a slab track and is also the direct cause for producing water pressure in the cracks. Hence, choosing the right loading method is the key to analyze the water damage of slab tracks. In order to identify the distribution characteristics of the vertical force acting on the slab track, the analytic expression of fastener load was derived, and the field test was conducted to verify the theoretical model. According to the distribution characteristics of fastener load and the area of crack filled with water, the loading method was presented to analyze the water damage of slab tracks, and the influence of loading characteristics on the hydrodynamic pressure and crack propagation was analyzed. The results show that the distribution of fastener load in the main affected zone approximately accords with the Gaussian distribution under the single wheel load. When under the action of double wheels, the superimposed effect makes the second derivative of the loading function to increase by 99.93%. The superimposed effect of three or more wheels is less than 1% and can be ignored. Considering that the hydrodynamic pressure is highly sensitive to the second derivative of loading function, the load applied on the track slab should be in the form of a bogie, and different loads should be applied step by step based on the time series. The distribution of hydrodynamic pressure along the crack is approximately equal to the cubic polynomial, and the pressure peak appears at the crack tip. Also, the pressure is proportional to the square of the running speed of the train. In the region with abundant rainwater and a poor drainage system, reducing the train speed and taking timely measures such as grouting can effectively reduce the water damage of slab tracks.

Exploiting nonlinearity in a flapping wing mechanism of a bio inspired micro air vehicle to enhance energy efficiency

In recent years, there was a great interest in developing flying drones with similar capabilities as flying insects. It is suggested that the flapping frequency of insects coincides with the resonance frequency of their flight mechanism to enhance the power consumptions. In this paper, the effect of nonlinearity in the flight mechanism on the power consumption is investigated. A simple nonlinear model of the insect flight mechanism is developed and normalised to study the effect of different parameters on its performance. Both bistable and hardening nonlinearity are considered. It is shown that for a harmonic loading, the bistable systems reach their peak power at lower frequencies when compared to the corresponding linear system. The maximum power factor of nonlinear oscillator would be lower than the liner one. It is also shown that the peak active power of the bistable system has a higher value than the linear system if the loading function is a pulse square signal.