bluuebunny/crossref_metadata_2025 huggingface dataset:
Innovative heat pipes and thermosyphons for renewable sources of energy application
Authors: Vasiliev Leonard , Zhuravlyov Alexander
Published: December 2018

In the paper the authors present possibilities of use two-phase heat-conducting devices at cooling technologies for PV and PV/T solar cooling and air-conditioning. Three ways to improve heat conductive properties of heat pipes and thermosyphons with help of nanotechnologies are considered: use of nanofluids, application of nanocoatings on heat loaded surfaces and polymer composites with nanoparticles producing. A mini bubbles generation of the working fluid inside the transparent thermosyphon evaporator with nanocoating under the solar radiation influence was observed. Nanotechnologies allow to intensify heat transfer processes and reduce energy losses in original designs of heat pipes and thermosyphons.
Mathematical model of flat plate solar thermal collector and its validation
Authors: Wasik Michał , Bugaj Marcin A. , Wiśniewski Tomasz S. , Klein Maciej , Chaja Patryk , Bykuć Sebastian
Published: December 2018

In order to predict solar thermal collector’s performance and optimization of control algorithms, proper mathematical models are necessary. Computer calculation technique provides tools for determination of modern materials impact on improvement of heat transfer inside the collector and minimization of heat loss. Such analysis is impossible by using standard technical datasheet provided by producer or by using empirical formulas. In the paper the authors present a mathematical model of a flat plate solar thermal collector based on the Hottel-Whiller-Bliss equation and criterial formula. The iterative algorithm solved steady state heat transfer equations for a glazed and an unglazed collector. The validation experiment was conducted under class AAA sun simulator for different inlet temperature and solar irradiation values. The unglazed PV/T and glazed solar thermal collectors were tested. For PV/T the relative difference, between measured and computed outlet temperatures, was below 5% and the highest value was reached for the lowest inlet temperature. The validation study showed that the experimental results reached good agreement with simulation predictions. Presented computation algorithm enables to predict influence of geometry changes on collector performance. The model could be used for optimization of the construction without using CFD methods, which need large computation resources.
Simplified methodology to estimate the emissivity for roof covers
Authors: Zapałowicz Zbigniew
Published: December 2018

In a number of countries, producers of roof covers are not obliged by law to estimate the reflectivity and emissivity of their products and make them generally available. However, information concerning these parameters that characterize the surface of roof cover is relevant for building's heat calculations. Adequate choice of kind and color of the roof surface affects the amount of heat transferred between the interior and the environment. Simplified research methodology has been proposed in the paper. This methodology requires that experimental research is carried out and characteristic temperatures of roof and of the air are determined. It is then possible to estimate the emissivity for roof cover from the model of energy balance.
Influence of desorption temperature on the thermodynamic performance of adsorption heat pump
Authors: Zwarycz-Makles Katarzyna
Published: December 2018

In the paper an analysis of the desorption temperature effect on the thermodynamic efficiency of the adsorption heat pumps is presented. The thermodynamic performance of heat pump is determined by Coefficient of Performance (COP) as well as exergetic efficiency coefficient (ηex) at the adsorption equilibrium conditions and compared to the performance at heat of evaporation of the working fluid conditions. Possible estimation of reduced efficiency of adsorption silica gel/water heat pump, as distinct from the equilibrium efficiency in realistic technical system is presented.
Experimental investigation of two-phase thermosyphon heat exchanger charged with acetone
Authors: Cieśliński Janusz T. , Fabrykiewicz Maciej
Published: December 2018

This paper presents thermal characteristics of prototype of a two-phase thermosyphon heat exchanger (TPTHEx) charged with acetone as a working fluid. The TPTHEx consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. The tested TPTHEx operates in a vacuum. Therefore, the working liquid is boiled in temperatures ranging from 33°C to 62°C. The overall heat transfer coefficient (OHTC) of the tested TPTHEx was estimated by the use of the Wilson method and the modified Peclet equation. The results obtained indicate a superiority of water over acetone as a working fluid. Moreover, it was shown that having a lower pressure in the shell-side of TPTHEx results in a higher overall heat transfer coefficient. The Wilson method and the modified Peclet equation predict OHTC with satisfactory agreement.
Experimental investigation on influence of microcapsules with PCM on propylene glycol rheological properties
Authors: Dutkowski Krzysztof , Fiuk Jacek Jan
Published: December 2018

This paper details an experimental study that was performed to investigate rheological properties of microencapsulated phase change slurry - mPCM (Micronal® DS 5039 X and ERGOLID EKO®- an aqueous solution of propylene glycol). Seven samples of mPCM slurry were prepared with different mass ratio of the Micronal® to the ERGOLID EKO®: 30:70, 40:60, 50:50, 60:40, 70:30, 80:20 and 90:10. The apparent viscosity-shear rate curves were obtained for spindle speed from 0.01 to 100 rpm (shear rate 0.0132 to 132.00 s-1 respectively). The steady state measurement of viscosity was carried out when the slurry reached constant temperatures, namely: 10.0; 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, 40.0 and 50.0°C. The apparent viscosity of slurries increases with the mPCM concentration in dispersion rises. Only the sample of 30% Micronal® may be considered as a Newtonian fluid within the test range. Increasing the shear rate ultimately causes apparent viscosity to decrease down to the Newtonian plateau, where it seems to be constant. The variation of the viscosity as a function of temperature and microcapsules concentration was accurately represented by a modified Vogel-Tamman-Fulcher equation at a mean absolute error (MAE) of 10.76%.
Experimental research on hydrodynamic instabilities during condensation of the pro-ecological refrigerant R1234yf in tubular minichannels
Authors: Kuczyński Waldemar , Denis Aleksander
Published: December 2018

The following paper presents the results of preliminary experimental research on the influence of instabilities of a hydrodynamic type on the condensation phase change process in tubular minichannels. The research was focused on a new pro-ecological refrigerant, R1234yf, intended as a substitute for R134a that currently is being phased out. The flow condensation phase change process was investigated for both steady and un-steady conditions in singular tubular minichannels with an internal diameter d = {1,44; 2,30; 3,30} mm. The scope of the analysis of the experimental data covered an estimation of propagation velocities for both pressure and temperature instabilities as well as the shrinkage of the condensation zone. The results were also compared with the previous results obtained for the flow condensation phase change of R134a refrigerant in tubular minichannels with the same internal diameters.
Thermal calculation of heat exchangers with simplified consideration of axial wall heat conduction
Authors: Roetzel Wilfried , Na Ranong Chakkrit
Published: December 2018

The usual thermal design and rating methods [1, 2] for heat exchangers neglect axial wall heat conduction in the separating walls and external shells of recuperators and in the solid matrix of regenerators. This may lead to undesirable undersizing. In this paper a simplified model is developed for the fast estimation of axial wall conduction effects in counterflow, parallel flow and mixed-mixed cross-flow recuperators. The dispersion model [3] is used to describe the performance deterioration of the exchanger with an effective fluid dispersion Peclet number for the correction of the heat transfer coefficients or mean temperature difference. The method is tested against analytical and numerical calculations for counterflow and parallel flow with good results. It is also shown how the method can be adapted to thermal regenerators and the related thermal calculation methods [1, 2]. An alternative approach is suggested for the consideration of lateral heat conduction resistance in the solid matrix.
Preliminary research on mass/heat transfer in mini heat exchanger
Authors: Wilk Joanna , Grosicki Sebastian , Kiedrzyński Krzysztof
Published: December 2018

In the paper the authors present the facility for model investigations of heat/mass transfer in the exchanger characterised by small dimensions. Determination of heat transfer coefficients is an important issue in the design of mini heat exchangers. The built facility enables measurements of mass transfer coefficients with the use of limiting current technique. The coefficients received from the experiment are converted into heat transfer coefficients basing on the analogy between mass and heat transfer. The exchanger considered consists of nine parallel minichannels with a square cross-section of 2mm. In real conditions during the laminar flow through the minichannels the convective heat transfer occurs. Analogous conditions are maintained during the model mass transfer experiment. The paper presents the experimental facility and the preliminary results of measurements in the form of voltammograms. The voltammograms show the limiting currents being the base of mass transfer coefficient calculations.
Dual-fuel combustion in a tangential PC-fired boiler of type OP-230 – computational simulations
Authors: Motyl Przemysław , Łach Jan
Published: December 2018

Syngas co-firing in coal fired boilers can be one of the prospective technologies which may help to retrofit some of still functioning older boilers. This study focuses on the results of CFD simulations of wood biomass-derived syngas co-firing with coal in an older mid-sized tangential PC-fired boiler of type OP-230. The design and the implementation of the combustion process predispose the boiler to the connection with the biomass gasifier in which low calorific syngas from solid raw biomass gasification can be produced and next used as a supplemental fuel in the coal furnace. The simulations were performed to predict the influence of the improvement of the air staging via the dual-fuel technique based on the indirect co-firing technology on both the reductions in NOx emissions relative to the baseline (no syngas) and the residence time of syngas particles in a zone with the temperature higher than 1123K. This way one can determine whether the boiler can be recommended to indirect co-firing of syngas derived from agricultural residues biomass or SRF gasification containing such troublesome components as chlorine and alkali.
Gas turbine unite inlet air cooling by using an excessive refrigeration capacity of absorption-ejector chiller in booster air cooler
Authors: Radchenko Roman , Radchenko Andrii , Serbin Serhiy , Kantor Serhiy , Portnoi Bohdan
Published: December 2018

Two-stage Gas turbine unite (GTU) inlet air cooling by absorption lithium-bromide chiller (ACh) to the temperature 15 °C and by refrigerant ejector chiller (ECh) to 10 °C through utilizing the turbine exhaust gas heat for changeable ambient air temperatures and corresponding heat loads on the air coolers for the south Ukraine climatic conditions is analysed. An excessive refrigeration capacity of combined absorption-ejector chiller (AECh) exceeding the current heat loads and generated at decreased heat loads on the air coolers at the inlet of GTU can be used for covering increased heat loads to reduce the refrigeration capacity of AECh. The GTU inlet air cooling system with an ambient air precooling booster stage and a base two-stage cooling air to the temperature 10 °C by AECh is proposed. The AECh excessive cooling capacity generated during decreased heat loads on the GTU inlet air coolers is conserved in the thermal accumulator and used for GTU inlet air precooling in a booster stage of air cooler during increased heat loads. There is AECh cooling capacity reduction by 50% due to the use of a booster stage for precooling GTU inlet ambient air at the expense of an excessive cooling capacity accumulated in the thermal storage.
Experimental tests of the prototypical micro-cogeneration system with a 100 kW biomass-fired boiler
Authors: Sornek Krzysztof , Goryl Wojciech , Filipowicz Mariusz
Published: December 2018

Renewable energy based micro cogeneration systems are an interesting option for domestic, agricultural and commercial sectors. In this paper, a dedicated system with a 100 kWth biomass-fired boiler was proposed. Developed system works according to modified Rankine Cycle operation. Steam generated in two shell and tube heat exchangers is used to power steam engine (connected with power generator) and then flows via condenser to degasifier. During the presented tests, the selected parameters of the boiler, oil circuit and steam/condensate circuit were analyzed. As was shown, the maximum thermal power taken from the oil circuit to evaporate condensate and superheat steam was ~105 kWth (it was ~91% of thermal power generated in the boiler). The value steam pressure varied from 2 to 5 bars during operation of the steam engine. Steam mass flow was then equal to ~105 kg/h, what allowed to generate electric power at a level of ~1.05 kWel. Such a low value resulted e.g. from limitations in the oil temperature, limitations in the steam temperature, steam pressure and steam flow, limitations caused by power generator’s construction, as well as other construction and operating parameters.
Dynamic analysis and characterization of a nonlinear bi-stable piezo-magneto-elastic energy harvester
Authors: Peterson João Victor Ligier Lopes , Lopes Vinicius Gonçalves , Cunha Americo
Published: December 2018

Energy harvesting is a very promising technology to provide low levels of power for small autonomous systems, which the applicability encompass a very wide range of areas, that spans from micro/nano sensors in engineering to state of art implants in medicine. The present work deals with the analysis and detailed characterization of a nonlinear bi-stable piezo-magneto-elastic energy harvester driven by a periodic external excitation. The dynamical system is studied in depth through bifurcation diagrams and basins of attraction. The level of chaoticity of the dynamical system is accessed very efficiently via the 0-1 test for chaos, which allows mapping the presence of dense regions of chaos without the help of the Lyapunov exponents.
Linear flexural natural frequencies and stability analysis of spinning Rayleigh beams: application to clamped-clamped beams.
Authors: Aouadi Mohamed Amine , Lakrad Faouzi
Published: December 2018

In the present paper 3D bending linear free vibrations of spinning Rayleigh beams are investigated. Four linear models, that differ in the linearization process, are studied. A focus on analytical computation of natural frequencies for a broad range of boundary conditions is highlighted. Then, the conditions of occurrence of divergence and flutter instabilities are determined. Finally, a case study consisting of a clamped-clamped Rayleigh beam is studied. It is found that the free vibrations destabilization process depends on the used linearization approach.
Effect of the localization on the response of a quasi-periodic electromagnetic oscillator array for vibration energy harvesting
Authors: Aouali Kaouthar , Kacem Najib , Mrabet Elyes , Bouhaddi Noureddine , Haddar Mohamed
Published: December 2018

Vibration energy harvesting by exploiting the multimodal approach in a quasi-periodic system is proposed. The quasi-periodic system, based on electromagnetic transduction, consists of two weakly coupled magnets mechanically guided by two elastic beams. Mistuning is achieved by varying the mechanical stiffness of one of the beams. These imperfections will lead to the vibration energy localization in regions close to the imperfections which will be exploited to maximize the harvested energy.
Global stability analysis of a delayed HIV model with saturated infection rate
Authors: Danane jaouad , Allali Karam
Published: December 2018

In this paper, the global stability of a delayed HIV model with saturated infection rate infection is investigated. We incorporate two discrete delays into the model; the first describes the intracellular delay in the production of the infected cells, while the second describes the needed time for virions production. We also derive the global properties of this two-delay model as function of the basic reproduction number R0. By using some suitable Lyapunov functions, it is proved that the free-equilibrium point is globally asymptotically stable when R0 ≤ 1, and the endemic equilibrium point is globally asymptotically stable when R0 ≥ 1. Finally, in order to support our theoretical findings we have illustrate some numerical simulations.
Programmed task based motion analysis of robotic systems equipped with flexible links and supports
Authors: Jarzębowska Elżbieta , Augustynek Krzysztof , Urbaś Andrzej
Published: December 2018

The automatic computational procedure to derivate dynamics equations of systems with programmed constraints modified to encompass compliant mechanical components in their structures is discussed in the paper. The dynamics analysis of the compliant manipulator model with a flexible link is presented as an example. The rigid finite element method is used in order to take into account the flexibility of the link. The formalism of joint coordinates and homogeneous transformations are used to describe the manipulator motion.
Numerical Approximation of LYAPUNOV-Exponents for Quasiperiodic Motions
Authors: Fiedler Robert , Hetzler Hartmut
Published: December 2018

This paper proposes an approach to approximate the LYAPUNOV -spectrum of quasiperiodic flows on isolated invariant manifolds numerically. Once the invariant manifold has been determined, integrations over the infinite, one dimensional time interval – as calculating the LYAPUNOV -spectrum for instance – can be transformed into an integral over a finite, p-dimensional domain, where p is the dimension of the manifold. The application of the proposed approach is demonstrated by calculating the LYAPUNOV -spectrum of periodic and quasiperiodic motions of a forced VAN-DER-POL equation. The results are compared to results from a classical time integration based method using a continuous GRAM-SCHMIDT orthonormalization.
Improving energy harvesting in excited Duffing harvester device using a delayed piezoelectric coupling
Authors: Ghouli Z. , Hamdi M. , Belhaq M.
Published: December 2018

The present work examines the influence of time delay introduced in the piezoelectric circuit of an excited Duffing harvester device with hardening stiffness on the vibration and voltage amplitudes. Specifically, we seek to exploit a delayed electrical circuit of the harvester to enhance its performance. We consider the case of a monostable system and we use a perturbation technique to approximate the periodic response and the corresponding voltage amplitude near the principal resonance. It is shown that for appropriate values of delay amplitude, the energy harvesting performance is improved over a certain range of coupling parameters and excitation frequencies. Numerical simulation is conducted to support the analytical predictions.
Optimization of vibration energy localization in quasi-periodic structures
Authors: Hbaieb Mariem , Kacem Najib , Ben Souf Mohamed Amine , Bouhaddi Noureddine , Haddar Mohamed
Published: December 2018

A mechanical periodic structure in presence of component perturbations can be a seat of a localization of vibration energy. In fact, it is well known that mistuned components have larger response levels than those of perfect components. This results in a localized energy, which can be tapped via harvesting devices. In this study, the dynamic behavior of a quasi-periodic system consisting in weakly connected linear oscillators is investigated. The main objective is to optimize the mistuning parameter, the coupling stiffness and the damping coefficient in order to functionalize the imperfection, which leads to the maximization of the localized vibration energy.
Application of vectorcardiography and recurrence-based methods to analysis of ECG signals
Authors: Iwaniec Joanna , Iwaniec Marek , Kalukiewicz Antoni
Published: December 2018

The paper concerns application of vectorcardiography and recurrence-based methods to analyze ECG signals. The first method involves recording the direction and magnitude of electrical forces of the heart by means of a continuous series of vectors that form a curving line around a center, while the second consists in representing the ECG signals in the phase space and searching for the recurrence properties of the registered signals. In both methods, change of analysis domain offers new opportunities for early diagnosis. In this work, discussed methods have been used for the purposes of analysis of selected ECG signals stored in the medical database. Vectorcardiograms were determined on the basis of ECG signals for the Farnk's leads. Signal analysis was carried out with the application of the recurrence plots (RP) method. The proposed approach simplifies assessment of the signal information content by providing patterns characteristic for different myocardial injury. Carried out research requires complementation by results of statistical analysis for various age groups and degrees of myocardial injury.
Using the Gottwald and Melbourne’s 0-1 test and the Hugichi fractal dimension to detect chaos in defective and healthy ball bearings
Authors: Kitio Kwuimy C. A. , Haj Mohamad T. , Nataraj C.
Published: December 2018

The paper considers the identification of chaotic behavior dynamics using the data extracted from an experimental model of rotor supported on rolling elements. A description of the methodis provided as well as an illustration using a standard dynamic map. The 0-1 test for chaos and the Higuchi dimension are shown to be eﬀective tool in the identification of chaotic behavior of the systembearing with and without faults.
Analysis of non symmetric FG sandwich plates under Thermo-mechanical loading using a novel shear deformation theory with stretching effect
Authors: Saidi H. , Bouchafa A. , Tounsi A. , Adda.Bedia A. E.A.
Published: December 2018

The analysis of non-symmetric functionally graded sandwich plates under thermo-mechanical loading is developed using a novel hyperbolic shear deformation theory and considering thickness stretching effects. This theory accounts for adequate distribution of the transverse shear strains in the thickness of the plate and satisfies the traction free boundary conditions on the top and bottom surface of the plates, thus a shear correction factor is not required. The governing equations of equilibrium of non-symmetric functionally graded sandwich plates can be obtained using virtual work principle and the closed form solutions are obtained by using Navier technique. The accuracy of the present results is established by comparing those with well known trigonometric shear deformation theories. The results are presented for deflections and stresses of non-symmetric simply supported square plates.
On the hysteretic operators with random parameters
Authors: Semenov Mikhail E. , Kanishcheva Olesia I. , Meleshenko Peter A. , Reshetova Olga O. , Pervezentzev Roman E. , Budanov Alexander V.
Published: December 2018

In this work we introduce the novel class of hysteretic operators with random parameters. We consider the definition of these operators in terms of the “input-output” relations, namely: for all permissible continuous inputs corresponds the output in the form of stochastic Markovian process. The properties of such operators are also considered and discussed on the example of a non-ideal relay with random parameters. Application of hysteretic operators with stochastic parameters is demonstrated on the example of simple oscillating system and the results of numerical simulations are presented.
Reliability modeling and prediction of passive controlled structures through Random Forest
Authors: You Weizhen. , Alexandre Saidi , Ichchou Mohamed , Abdel Zine , Zhong Xiaopin
Published: December 2018

Reliability prediction plays a significant role in risk assessment of engineering structures. Mathematically, the prediction task can be seen as a classification (regression) procedure. In this aspect, machine learning methods have recently shown their superior performance over others in various research domains. Random forest (RF) is distinguished for its robustness and high accuracy in modeling and prediction work. However, its application in the area of structural reliability has not been widely explored. This study aims to explore the feasibility of RF as well as examine its performance in modeling and prediction of structure reliability in passive control mode. A numerical example is introduced in the simulation part to evaluate performance of the proposed method in different perspectives.
Design of a quasi-periodic vibration energy harvester based on an electromagnetic technique
Authors: Zergoune Zakaria , Kacem Najib , Bouhaddi Noureddine
Published: December 2018

In the present paper, a quasi-periodic vibration energy harvester with magnetic coupling is proposed using the benefits of the energy localization. The proposed quasi-periodic system consists of moving magnets held by elastic structures and coupled by a magnetic force. The mistuning of the device can be achieved by changing either the linear mechanical stiffness or the mass. The whole system has been modelled by forced Duffing equations for each degree of freedom, which include the magnetic nonlinearity and the mechanical damping. The governing equations have then been solved using the harmonic balance method coupled with the asymptotic numerical method. The obtained numerical results show that the total harvested power was increased by 11 % with a bandwidth of 2.7 % thanks to the energy localization phenomenon compared to the reference case.
Bifurcation, chaotic and hysteresis phenomena of broadband tristable energy harvesters
Authors: Zhou Shengxi , Cao Junyi , Litak Grzegorz
Published: December 2018

We analyze energy harvesting using a mechanical resonator with three potential wells. Nonlinear effects are leading to frequency broadband voltage response via bifurcations, multiple solutions and dynamical hysteresis. We show the characteristic features of the obtained solutions. In particular, basins of attraction of solutions are discussed.
Energy harvesting in a delayed Rayleigh harvester device
Authors: Kirrou I. , Bichri A. , Belhaq M.
Published: December 2018

In the present work, we report on energy harvesting in a delayed Rayleigh oscillator coupled to a piezoelectric harvester device. Analytical investigation using the multiple scales method is performed to obtain approximation of the periodic and QP amplitude response. The influence of different parameters of the harvesting system on the output power coupling to periodic and QP vibrations is examined. Results show that for appropriate values of the delay parameters, QP vibrations can also be exploited to harvest energy with good performence.
Nouvelle approche pour la caractérisation du dévissage et desserrage des assemblages vissés
Authors: Delcher Christophe
Published: December 2018

Différents tests permettant d’évaluer la performance au desserrage des assemblages vissés existent. Néanmoins, leurs protocoles et conditions d’essai sont spécifiques et souvent assez peu détaillés. De ce fait, réaliser des tests comparatifs répétables, en particulier inter-laboratoires, devient rapidement délicat et sujet à controverse. Dans le cadre de la commission R&D Fixations regroupant les fabricants français de fixations et suite aux études menées sur le sujet du dévissage spontané menées par le CETIM et ARTEMA Fixations (anciennement AFFIX), des travaux sont actuellement en cours afin de normaliser (norme expérimentale française) une méthodologie générale pour la réalisation d’essai de desserrage quel qu’il soit. Le présent document intègre une première partie exposant un panorama des différents tests de desserrage existants. Une seconde partie détaille la nouvelle approche de caractérisation du seuil de desserrage, applicable à tous types de tests déjà existants.
Implementation issues of Yld2000-2d model under larger biaxial yield stress
Authors: Zhang Yong , Zhang Qing , Sun Yuantao
Published: December 2018

In the field of sheet forming simulation, yield models serve as one of the most crucial factors for accurate computational results, and plane stress yield models have the capacity for both high efficiency and high accuracy. During recent years, applications of the Yld2000-2d model to sheet forming simulation of steel and aluminum have become increasingly popular due to its outstanding ability in describing these materials’ yield phenomena. For the computational implementation of this model, the Newton–Raphson iteration can correctly obtain the solutions of return mapping equations in most cases. However, it has been found in this work that the traditional iteration process may fall into a convergence problem when the yield stress is prominent (σb/σ0 > 1.2). To solve the new finding problem, a line search algorithm is added to the Newton–Raphson iteration process. Biaxial tension simulation results show that the line search algorithm could converge successfully even when σb/σ0 = 1.4. The simulation of the Erichsen test shows the applicability of the established Yld2000-2d model combined with a line search algorithm in the Newton–Raphson iteration process.
Simulations of autonomous fluid pulses between active elastic walls using the 1D-IRBFN method
Authors: Ahmed Fatima Z. , Mohammed Mayada G. , Strunin Dmitry V. , Ngo-Cong Duc
Published: December 2018

We present numerical solutions of the semi-empirical model of self-propagating fluid pulses (auto-pulses) through the channel simulating an artificial artery. The key mechanism behind the model is the active motion of the walls in line with the earlier model of Roberts. Our model is autonomous, nonlinear and is based on the partial differential equation describing the displacement of the wall in time and along the channel. A theoretical plane configuration is adopted for the walls at rest. For solving the equation we used the One-dimensional Integrated Radial Basis Function Network (1D-IRBFN) method. We demonstrated that different initial conditions always lead to the settling of pulse trains where an individual pulse has certain speed and amplitude controlled by the governing equation. A variety of pulse solutions is obtained using homogeneous and periodic boundary conditions. The dynamics of one, two, and three pulses per period are explored. The fluid mass flux due to the pulses is calculated.
Deregulation of laws and border facilitations, and their impact on the increase of competitiveness of Polish seaports
Authors: Adamowicz Magdalena
Published: December 2018

This article attempts to explore the effects caused by the implementation of facilities for maritime entrepreneurs introduced under the act deregulating economic law (hereinafter: "Ports 24h" or port package). Moreover it was analysed whether the procedures implemented by the Customs Service and border units, and in particular the simplified procedure, one stop shop and single window, shortened the time of customs clearance in ports. It was examined whether new solutions affected seaports in Poland and helped to build their competitive advantage over the Baltic Sea. The port of Gdansk was particularly interested due to the annual increase in transhipments. There is a surprising lack of studies on customs conveniences in sea ports. The bulk of academic work focuses on the competitiveness of sea ports as seen through infrastructural investments, with no consideration given to factors such as stable, clear and reliable law which does not impede enterprises in their business.
Analysis of the market concentration of the container shipping markets – selected issues
Authors: Charłampowicz Jędrzej
Published: December 2018

The value of maritime freight transport grows yearly both in terms of value and quantity. The dynamic development of container shipping is responsible for this state of affairs. The maritime container transport market is strongly integrated on the supply side. The aim of this paper is to determine, based on empirical data, whether the market is still competitive for its participants on the supply side. For this purpose, the 2 indicators of concentration were calculated, namely CRx-concentration for 4 operators with the largest market share, and Herfindahl-Hirshmann Index for TOP 10 and TOP 20 operators, based on AXS Alphaliner TOP100 and various issues of UNCTAD Review of Maritime Transport. The results of the calculations indicate that the market is still competitive, although it is heading towards a direction in which several large entities will dictate the conditions to other participants.
The long arm of the sustainable port
Authors: Laskowski Bartłomiej
Published: December 2018

As there has been a lot written regarding sustainable transportation methods, there is still some opportunity to enhance the perspective on the economic advantage of the zero-emission supply chain. This has the potential of an accelerated adaptation in a cost to serve delivery system. The paper will introduce into the discussion the concept of working with nature, to develop durable structures and its capability of delivering value on its interactive environment or face the natural selection process. The functionality of the Port will be revisited in contrast of today’s confinements of operation, while creating an opportunity to strengthen its perspective on its deliverables and reassess today’s market. Further it will reflect whether sustainable transportation planning is still a choice or a competitive requirement.
The evaluation of the attractiveness of marine container terminal sector: analysing the polish sector
Authors: Marek Robert
Published: December 2018

The importance of attractiveness of the marine container terminal operators have significantly increased in the recent years due to them influence on the worldwide economy. This article aim is to evaluate the attractiveness of marine container terminals by using a qualitative analysis. The main point is to define the attractiveness of the Marine Container Terminal Operators (MCTOs) located in Poland. The qualitative analysis has provided arguments to conclude that marine container market in Poland currently is attractive from the point of existing MCTOs in this sector. The developed model helps to estimate the attractiveness of the marine container terminal market (MCTM) in Poland.
The efficiency of a supply chain with the use of maritime transport on the example of the apparel industry
Authors: Milewski Dariusz , Milewska Beata
Published: December 2018

The paper presents the problem of the impact of the competitiveness of maritime transport on the efficiency of global supply chains on the example of the apparel industry. With the use of a model developed by the authors, simulations of the profitability of the sourcing in low-costs countries (Bangladesh, China) have been conducted. The model takes into account the specificity of the apparel industry, parameters of cargo, value of goods, and demand characteristics. If freight rates for maritime transport services were to increase significantly, the profitability of production in the Far East compared to local or regional production would be lower particularly for cheaper products. The level of these freight rates is not the main factor of the efficiency of this strategy. Simulations revealed, that changes of costs of production has greater impact on this profitability. In the garment market the possibility of quick response to demand is often more important than costs. The calculations were made on the basis of data obtained from Polish companies, which order production in countries with low production costs and transport garment in containers by sea and from transport and logistics operators.
Analysis of the seaport value chain as a method for assessing its strategic potential
Authors: Montwiłł Andrzej
Published: December 2018

The aim of the paper is to describe the analysis of the seaport value chain as a method for assessing its strategic potential. This potential is understood as the port's ability to develop and improve its competitive position in sectors that are defined as part of the assessment of this potential. In the paper, key aspects of the seaport value chain analysis were described in the form of a summary of previous research on this subject. The seaport is understood as a system in which a number of interpenetrating processes for passengers, freight, means of transport and enterprises are carried out. To better illustrate key aspects of the value chain analysis, examples of selected processes implemented at seaports were used. Next, the paper presents the results of research interpreting the impact of various internal factors on the efficiency of the port value chain that translates into its strategic potential, where the issue was repeated using specific cases. In the final part of the paper, based on previous research, the significance of the analysis of the seaport value chain to assess the strategic potential of the seaport was pointed out. Moreover, in this part of the paper the chosen case was used to indicate the level of applicability of the research carried out.
External effects in the maritime sector leading to new economic perspectives.
Authors: Rozmiarek Magdalena , Faasse Ad
Published: December 2018

Our present economic system is facing some real challenges. It is a so-called linear system like “take-make-use-lose”. Sustainable economic development requires valuing (environmental) resources correctly and factoring them into production and consumption decisions. Having a focus on the economic production process, external effects do not seem to fit in the linear system. So-called external effects are not included in economic models, business decisions etc. External effects like the Sustainable Development goals and legal actions in court are of growing importance for economic developments ranging from port development to design of ships and logistics. The distinction Economic Capital, Social Capital and Natural Capital is helpful in creating consciousness about the concept of circular economy. Nature provides tools, systems and knowledge from 3.8 billion years of evolution that will enable us to enter and develop new circular economic developments, to develop real "green ports”; to combine divergent functions in a smart way.
Dealing with Maritime Economy at the Local Level. Trends along the Coastal Poland
Authors: Szejgiec-Kolenda Barbara , Zaucha Jacek
Published: December 2018

Although the interest in the concept of ‘blue economy’ has grown rapidly in recent years, the most studies assess maritime activities’ size, scope, basic trends or position in national economy mostly at the basin/national, sometimes even regional level and there has been little research taking into account the local dimension of maritime economy. This is partly due to a lack of appropriate statistical data concerning maritime economy. The aim of the analysis is to define and describe the local maritime economy in Poland as well as to establish its importance for various territories. This study considers the challenges that maritime local studies face in terms of data availability and provides a research path that is to some extent complementary to analyses at the national and regional level. It explores a two-step approach to measure and evaluate a maritime local economy in Poland in 2016: (1) a more general countrywide attempt to identify the problem; (2) addressing the local dimension of blue economy in the spatially limited area (coastal regions). Moreover, the approach allows to identify territorial differences (functional region types), the extent to which these activities differ among local economies and the pathways for maritime economy structures transitions along the coastal Poland.
Blutungsmanagement unter direkten oralen Antikoagulanzien (DOAK)
Authors: Koscielny Jürgen , Rosenthal Christoph , von Heymann Christian
Published: December 2018

Was ist neu?

Aktueller Stand Kein Gerinnungstest kann die Blutungswahrscheinlichkeit vorhersagen. Es lassen sich lediglich Pharmakokinetik und Momentaufnahme des Plasmaspiegels der DOAK messen. Zur Interpretation von Gerinnungstests ist es notwendig, u. a. den Zeitpunkt der letzten DOAK-Einnahme sowie die Organfunktionen von Niere und Leber zu kennen.

Der präoperative Notfallpatient Nicht zu verschiebende Operationen müssen ggf. auch unter wirksamen Spiegeln der DOAK durchgeführt werden, wobei aufgrund des Thromboembolierisikos und des nicht letztendlich gesicherten Wirksamkeitsnachweises derzeit von einer prophylaktischen Gabe von Faktorenkonzentraten abzuraten ist.

Behandlung von lebensbedrohlichen Blutungen unter DOAK-Therapie Vital bedrohliche Blutungen erfordern ein spezielles Hämostasemanagement. Als direkte Antidot-Therapie kann für Dabigatran das monoklonale Antikörperfragment Idarucizumab verabreicht werden, für die Xa-Inhibitoren steht PPSB (Prothrombinkomplexpräparat) zur Verfügung.
Neue europäische Empfehlungen zum Blutdruckmanagement im Alter
Authors: Hoffmann Ute , Thrun Jan-Marc
Published: December 2018

Was ist neu?

Neuer Standard für Messmethoden Unter anderem ist die korrekte Blutdruckmessung unter standardisierten Bedingungen in den letzten Jahren in den Fokus gerückt. Dies beinhaltet vor allem die richtige Anwendung von validierten Messgeräten und die Einhaltung eines einheitlichen Messablaufs mit Ruhezeit vor der Messung, dem Durchführen von mehreren Messzyklen ebenso wie der Messung im Stehen bei älteren Patienten. Wegen des höheren Auftretens eines Weißkitteleffekts und der orthostatischen Hypotonie sowie zur Therapiekontrolle wird bei älteren Menschen auch immer die häusliche Selbstmessung empfohlen.

Welche Messgeräte für ältere Menschen? Ältere Patienten sollten die Blutdruckmessung mit validierten Oberarmmessgeräten mit gut ablesbarem Display durchführen.

Blutdruckzielwerte Die neuen europäischen Leitlinien zum Management der arteriellen Hypertonie empfehlen konkrete und z. T. niedrigere Blutdruckzielwerte zumindest für fitte ältere Patienten. Bei der Einteilung in Gruppen spiegelt sich v. a. die Berücksichtigung von Frailty, der Selbstständigkeit, der Begleitmedikation und der Therapieverträglichkeit der älteren Menschen wider.

Nicht-medikamentöse und medikamentöse antihypertensive Strategie bei älteren Menschen Auch älteren Menschen sind, sofern möglich, nicht-medikamentöse Maßnahmen zu empfehlen. Als medikamentöse Initialtherapie eignet sich eine Kombinationstherapie beginnend mit den jeweils niedrigsten Dosen, idealerweise als „single pill“.
Primäre und sekundäre arterielle Hypertonie –Update 2018
Authors: Hausberg Martin , Sanner Bernd
Published: December 2018

Was ist neu?

Bedeutung und Methodik der Blutdruckmessung Fehler bei der Blutdruckmessung sind eine Hauptursache für eine schlechte Blutdruckkontrolle und auch für eine Fehlklassifizierung von Normotonikern und Hypertonikern.

Langzeit-Blutdruckmessung Die 24-Stunden-Langzeit-Blutdruckmessung ist deutlich aussagekräftiger im Hinblick auf die Einschätzung des Mortalitätsrisikos als die Gelegenheits-Blutdruckmessung beim Arzt. Insbesondere die kleine Patientengruppe der sog. maskierten Hypertoniker ist gefährdet.

Blutdruckvariabilität Eine erhöhte Blutdruckvariabilität scheint ein Risikofaktor für die Entwicklung einer Demenz zu sein und steigert nach transitorisch ischämischer Attacke oder kleinem Schlaganfall das kardiovaskuläre Risiko.

Zielblutdruck Zu dem Thema gibt es in 2017 und 2018 mehrere neue Leitlinien. Gemeinsam in allen Leitlinien ist die Empfehlung von niedrigeren Zielblutdruckwerten bei arterieller Hypertonie für die Mehrheit der Patienten und ein strafferes pharmakologisches Therapieregime.
Systemtherapie des frühen und metastasierten Mammakarzinoms
Authors: Fehm Tanja , Müller Volkmar
Published: December 2018

Was ist neu?

Adjuvante Systemtherapie des Mammakarzinoms Bei Patientinnen mit hohem Rezidivrisiko ist eine taxan- und anthrazyklinhaltige Chemotherapie indiziert. Zusätzlich können HER2-positive Patientinnen adjuvant neben Trastuzumab zusätzlich Pertuzumab adjuvant bei negativem Hormonrezeptorstatus und/oder Nodalpositivität erhalten. Bei prämenopausalen Hormonrezeptor-positiven Patientinnen mit mittlerem und hohem Rezidivrisiko ist eine zusätzliche Gabe eines GnRH-Analogons zur Tamoxifentherapie sinnvoll. Auch die Kombination von Aromatasehemmern und GnRH-Analogona stellt für diese Patientinnengruppe eine Option dar. In der Postmenopause ist die endokrine Therapie mit Aromatasehemmern der alleinigen Tamoxifentherapie überlegen. Nach Aromatasehemmer-Gabe erscheint eine erweiterte adjuvante endokrine Therapie länger als 5 Jahre nur bei Patientinnen mit Risikofaktoren sinnvoll.

Systemtherapie des metastasierten Mammakarzinoms CDK-4/6-Inhibitoren in Kombination mit einer endokrinen Therapie verlängern im Vergleich zu einer alleinigen endokrinen Therapie das progressionsfreie Überleben. Für Patientinnen mit HER2-positivem Mammakarzinom konnte durch die Ergänzung der systemischen Therapie um die duale Blockade (Trastuzumab plus Pertuzumab) sowie die Etablierung von T-DM1 in der Zweitlinientherapie eine bedeutsame Verbesserung des Gesamtüberlebens erreicht werden. Innovativ Therapieoptionen wie PARP-Inhibitoren, Checkpointinhibitoren oder neue Antikörperkonjugate werden derzeit noch überprüft.