Natural and forced turbulent mixing in rod bundles

The effects of mass flow rate and subchannel configuration on the turbulent interchange between adjacent subchannel in simulated rod bundle were investigated. The simulated rod bundle was made by arranging seven 1.913 cm diameter acrylic plastic rods in an equilateral triangular pattern in a tube 8.89 cm inside diameter. The overall test section was 152.4 cm in length with a 60.96 cm long mixing section. Design of the test section allowed a study of turbulent lateral mixing between triangular-triangular, triangular-trapezoidal and trapezoidal-trapezoidal subchannels configuration. A tracer technique was used with Rhodamine B dye as tracer. Dye concentration was measured with two sets of hypodermic needles. The tracer initially injected in one of the adjacent subchannels was free to diffuse into the other subchannels. Using a lumped parameter approach, an analytical model was developed to describe axial change of concentration along the test section. Measured concentration and subchannel mass flow rate were used for numerical calculation of turbulent mixing rate. Turbulent mixing rate in the rod bundle with wire wrap was also investigated. Following are the results of this study: 1. Turbulent mixing is a function of the subchannel mass flow rate, and increases when subchannel Reynolds number increases. 2, Turbulent mixing is not significant function of the subchannel configuration. 3. Subchannel mixing can be compared to turbulent mixing in the turbulent core of a fluid flowing in a circular tube. 4. The flow conditions in the vicinity of the gap space are very important, especially when mean velocities in adjacent subchannels are not equal. 5. The friction factor for the rod bundle matrix with smooth rods follows Blasius' equation. 6. Wire wraps on the rods increased mixing especially for the higher Reynolds numbers

DYNAMIC RESPONSE OF HEAVY-LIFTING SHIPYARD MACHINES TO RESONANT ENVIRONMENTAL LOAD CONDITIONS

Climate changes on the planet have led to the appearance of extreme natural influences on large structures in ports and shipyards, as well as at-sea structures. One of the most variable meteorological effects in space and time is the wind. This paper provides the manner of dynamic modelling of wind loads on a tall portal-rotating crane structure. The gust of wind is modelled as a wave quantity variable in time and altitude of flow. Dynamic wind activity on tall structures is used to obtain a structure’s behaviour with regard to extreme climate events when frequently resonant influences occur. This is performed by non-linear transient FEM analysis. Structural damping is modelled by conversion to the equivalent viscous damping. Eigenfrequencies are obtained by applying the Lanczos method which combines the tracking method and the transformation method. The paper contains an originally developed dynamic model, experimentally verified stiffness, and internal static quantities. The aim of the paper (Case Study) is to obtain the wind activity which would cause the loss of dynamic stability of the crane due to multiple resonant gusts of wind. Such analyses can be employed to determine the real risk from a potential failure in tall structures caused by environmental, meteorologically registered activities

DYNAMICAL STRUCTURAL RELIABILITY BASED ON THE CASE STUDY ANALYSIS

An important aspect of the support structures' design is their dynamic behavior under extreme conditions. Especially actual are the large-range structures. Therefore, the support structure of a mining machine for transportation of tailings (stacker) is observed dynamically. The dynamic behavior of the entire structure in an incidental situation – the failure of a support tie rod for the pylon-platform connection is observed. The aim of this research is to predict the consequences of breaking a structure element for the rest of the support structure. This paper shows the theoretical modeling of structures, numerical solution of differential equations, and vibrations after simulated incident. The paper presents special design – the way of structure testing from the aspect of high structural availability and ability of the structure to compensate overload caused by the incident. To check the model, a real stacker structure was used at the surface mine RBB (The copper mine – Bor, Serbia). The developed numerical model showed the internal stress states of the structure and the law of vibration after the incident. On the basis of more case study analyses, the overall reliability and ability of redundancy of the structure were evaluated

From qualitative data to quantitative models: analysis of the phage shock protein stress response in Escherichia coli

Background Bacteria have evolved a rich set of mechanisms for sensing and adapting to adverse conditions in their environment. These are crucial for their survival, which requires them to react to extracellular stresses such as heat shock, ethanol treatment or phage infection. Here we focus on studying the phage shock protein (Psp) stress response in Escherichia coli induced by a phage infection or other damage to the bacterial membrane. This system has not yet been theoretically modelled or analysed in silico. Results We develop a model of the Psp response system, and illustrate how such models can be constructed and analyzed in light of available sparse and qualitative information in order to generate novel biological hypotheses about their dynamical behaviour. We analyze this model using tools from Petri-net theory and study its dynamical range that is consistent with currently available knowledge by conditioning model parameters on the available data in an approximate Bayesian computation (ABC) framework. Within this ABC approach we analyze stochastic and deterministic dynamics. This analysis allows us to identify different types of behaviour and these mechanistic insights can in turn be used to design new, more detailed and time-resolved experiments. Conclusions We have developed the first mechanistic model of the Psp response in E. coli. This model allows us to predict the possible qualitative stochastic and deterministic dynamic behaviours of key molecular players in the stress response. Our inferential approach can be applied to stress response and signalling systems more generally: in the ABC framework we can condition mathematical models on qualitative data in order to delimit e.g. parameter ranges or the qualitative system dynamics in light of available end-point or qualitative information.Medical Research Council (Great Britain)Biotechnology and Biological Sciences Research Council (Great Britain)Wellcome Trust (London, England)Royal Society (Great Britain) (Wolfson Research Merit Award

Advanced Magnetic Materials Methods and Numerical Models for Fluidization in Microgravity and Hypogravity

To support long-duration manned missions in space such as a permanent lunar base, Mars transit, or Mars Surface Mission, improved methods for the treatment of solid wastes, particularly methods that recover valuable resources, are needed. The ability to operate under microgravity and hypogravity conditions is essential to meet this objective. The utilization of magnetic forces to manipulate granular magnetic media has provided the means to treat solid wastes under variable gravity conditions by filtration using a consolidated magnetic media bed followed by thermal processing of the solid wastes in a fluidized bed reactor. Non-uniform magnetic fields will produce a magnetic field gradient in a bed of magnetically susceptible media toward the distributor plate of a fluidized bed reactor. A correctly oriented magnetic field gradient will generate a downward direct force on magnetic media that can substitute for gravitational force in microgravity, or which may augment low levels of gravity, such as on the Moon or Mars. This approach is termed Gradient Magnetically Assisted Fluidization (G-MAFB), in which the magnitude of the force on the fluidized media depends upon the intensity of the magnetic field (H), the intensity of the field gradient (dH/dz), and the magnetic susceptibility of the media. Fluidized beds based on the G-MAFB process can operate in any gravitational environment by tuning the magnetic field appropriately. Magnetic materials and methods have been developed that enable G-MAFB operation under variable gravity conditions

Multi-band optical variability of a newly discovered twelve blazars sample from 2013-2019

Here we present the first optical photometric monitoring results of a sample of twelve newly discovered blazars from the ICRF - Gaia CRF astrometric link. The observations were performed from April 2013 until August 2019 using eight telescopes located in Europe. For a robust test for the brightness and colour variability, we use Abbe criterion and F-test. Moreover, linear fittings are performed to investigate the relation in the colour-magnitude variations of the blazars. Variability was confirmed in the case of 10 sources; two sources, 1429+249 and 1556+335 seem to be possibly variable. Three sources (1034+574, 1722+119, and 1741+597) have displayed large amplitude brightness change of more than one magnitude. We found that the seven sources displayed bluer-when-brighter variations, and one source showed redder-when-brighter variations. We briefly explain the various AGN emission models which can explain our results.Comment: 14 pages, 8 figures, 11 tables, 6 supplement figures can be provided on request, MNRAS in pres

Hydrodynamic Effects of Particle Chaining in Liquid-Solid Magnetofluidized Beds

In a fluidized bed of magnetically susceptible particles, the presence of a magnetic field induces particle chaining due to interparticle magnetic forces. The particle chains offer less resistance to flow, resulting in a decrease of the drag coefficient. The change in drag coefficient as a function of hydrodynamic and magnetic operating conditions of a liquid-solid magnetofluidized bed is studied

INDIVIDUALIZATION CONCEPT IN HOUSING ARCHITECTURE

Although single-family housing in the city is considered higher quality and preferred type of housing, housing crisis, as a permanent actual problem in the world, requires adequate solutions. In this sense, housing in multi-family housing buildings can be considered as a necessity (social, moral, economic, etc.), but in fact, now and in the future, it is the main form of housing construction which can give the solution for housing problems. However, to make this housing type more attractive and acceptable to the occupants, it is necessary to improve it by the implementation of individualization modalities, and in that way make its qualities much closer to the preferred single-family housing

Effects of capacity sharing on delays and re-routings in European ATM

In this paper we analyse the effects of capacity sharing between Area Control Centres on delays and re-routings. We assume two different design options for capacity sharing (within Air Navigation Service Providers and within Functional Airspace Blocks) and compare them to a baseline scenario. Using the CADENZA optimization and simulation model, we build a case study of a busy day in the ECAC area, using 100 different scenario runs in order to capture traffic variability as well as capacity reductions. Results show that capacity sharing leads to a decrease of delay and re-routing costs that outweighs the additional costs of enabling capacity sharing even if we assume relatively high additional costs per shared sector-hour. Moreover, it can be shown that capacity sharing within ANSPs already delivers 3/4 of the benefits that can be achieved via capacity sharing within FABs.This project has received funding from the SESAR Joint Undertaking within the framework of SESAR 2020 and the EU's Horizon 2020 research and innovation programme under the Grant Agreement Number 893380.Peer ReviewedPostprint (published version