One-of-a-Kind Footbridge, Lublin, Poland

The paper presents the construction of a steel footbridge in the People’s Park in Lublin.The initiation and development of the architectural design of an interesting and,as it eventually turned out,aesthetically pleasing footbridge is discussed.Two teams of architects and bridge engineers worked in parallel on the design.The design process of the footbridge structure is discussed along with its trial installation and on-site construction.The span of the footbridge is short,but its structure is innovative.For this reason its numerical model was developed used as a basis for an analysis of the dynamic response of the designed structure.The basic element of the acceptance procedure was constituted by a dynamic test load and an analysis of the pedestrian footbridge user comfort.Last but not least,the final section reviews the aesthetic canons of bridges and focuses on the footbridge in question in this context.A statistical measure of the aesthetic impression induced by a visit to the footbridge was applied resulting in a predictable and obvious final aesthetical assessment.

Tensile and tear-type fracture toughness of gypsum material:Direct and indirect testing methods

In this context,four specimens,i.e.(i)circumferentially notched cylindrical torsion(CNCT),(ii)circum-ferentially notched cylindrical direct tension(CNCDT),(iii)edge notch disc bend(ENDB)and(iv)three-point bend beam(3PBB),were utilized to measure the modesⅠandⅢfracture toughness values of gypsum.While the CNCT specimen provides pure modeⅢloading in a direct manner,this pure mode condition is indirectly produced by the ENDB specimen.The ENDB specimen provided lower KⅢc and a non-coplanar(i.e.twisted)fracture surface compared with the CNCT specimen,which showed a planar modeⅢfracture surface.The ENDB specimen is also employed for conducting pure modeⅠ(with different crack depths)and mixed modeⅠ/Ⅲtests.KIc value was independent of the notch depth,and it was consistent with the RILEM and ASTM standard methods.But the modeⅢfracture results were highly sensitive to the notch depth.While the fracture resistance against modeⅢwas significantly lower than that of modeⅠ,the greater work of fracture under modeⅢwas noticeable.

The impact of dielectrics on the electrical capacity, concentration, efficiency ozone generation for the plasma reactor with mesh electrodes

This paper presents experimental results concerning the effect of dielectric type on ozone concentration and the efficiency of its generation in plasma reactor with two mesh electrodes.Three types of dielectric solid were used in the study; glass, micanite and Kapton insulating foil. The experiments were conducted for voltage ranges from 2.3 to 13 k V. A plasma reactor equipped with two 0.3×0.3 mm^2 mesh electrodes made of acid resistant AISI 304 mesh was used in the experiments. The influence of the dielectric type on the concentration and efficiency of ozone generation was described. The resulting maximum concentration of the ozone was about 2.70–9.30 g O3 m^-3, depending on the dielectrics used. The difference between the maximum and the minimum ozone concentration depends on the dielectric used,this accounts for 70% at the variance. The reactor capacity has also been described in the paper; total Ct and dielectric capacitance Cd depending on the dielectric used and its thickness.

Influence of the fly ash fraction after grinding process on the hydrothermal synthesis efficiency of Na-A,Na-P1,Na-X and sodalite zeolite types

The fly ashes(Class F and C)have been successfully used as the main substrates in the hydrothermal syntheses of Na-A,Na-P1,Na-X and sodalite zeolites.Both ashes and their derivatives after milling with magnetic field grinder were used.The paper investigates the effect of fly ash fraction size on the syntheses efficiency and physicochemical properties of the obtained zeolites.The starting material and obtained zeolites were subjected to physicochemical characteristics using X-ray diffraction,X-ray fluorescence,particle size analysis,and scanning electron microscopy methods.The paper showed a significant effect of the used fly ash fractions on the quantity,purity,quality and level of crystallinity of the zeolites phase obtained.The application of the grinding process prior to the syntheses of zeolites,with a relatively small financial outlay,significantly increases their application potential.Obtained zeolites are a promising material in the context of their use,inter alia,in environmental protection.

New Concept of Animal Underpass - Green Bridge

In Poland, the ecological corridor map overlaps with forests, as well as with the road network. The police have recorded near a 100% increase in animal mortality over the last decade. In most cases, bridges automatically serve as passages for animals, even if they have not been considered and designed for such a role. The following facts are importand: silence is positive for animals, natural guides are better then fences and walls, gentle lighting moderates car lights at night. Therefore, the semi-transparent canopy-type noise screens should be used, as well as olfactory tracks. The solution proposed here is beneficial for both the environment and road users. For the proper functioning of the bridge, it is crucial to take into consideration that animals are more efficiently guided by their smell than by channelling fences. However, the commonly used fences would also be provided. Olfactory traces can come in two kinds: animal faecal matter and mating scents. In a natural habitat, decreasing the immediate proximity between animals and humans should also be considered. A multi-criteria analysis was conducted to prove benefits both in terms of bridge maintenance effort and the impact on the environment. The criteria were selected on the basis of expert opinions.

Piezomagnetic vibration energy harvester with an amplifier

We study the effect of an amplification mechanism in a nonlinear vibration energy harvesting system where a ferromagnetic beam resonator is attached to the vibration source through an additional linear spring with a damper.The beam moves in the nonlinear double-well potential caused by interaction with two magnets.The piezoelectric patches with electrodes attached to the electrical circuit support mechanical energy transduction into electrical power.The results show that the additional spring can improve energy harvesting.By changing its stiffness,we observed various solutions.At the point of the optimal stiffness of the additional spring,the power output is amplified a few times depending on the excitation amplitude.

Enhance limit cycle oscillation in a wind flow energy harvester system with fractional order derivatives

Advances in material science and mathematics in conjunction with tech- nological needs have triggered the use of material and electric components with fractional order physical properties. This paper considers the mathematical model of a piezoelectric wind flow energy harvester system for which the capacitance of the piezoelectric material has fractional order current-voltage characteristics. Additionally the mechanical element is assumed to have fractional order damping. The analysis is focused on the effects of order of derivatives on the appearance and characteristics of limit circle oscillations （LCO）. It is obtained that, the order of derivatives to enhance the amplitude of LCO and lower the threshold condition leading to LCO. The domains of efficiency of the system are illustrated in various parameters spaces.

修复零件中堆焊涂层内部缺陷的评估（英文）

本文采用计算机断层扫描技术对堆焊效果进行评估。采用钨极惰性气体保护进行堆焊,焊料为耐磨涂层的合金线。讨论了最新的堆焊材料及其应用。对堆焊涂层的缺陷进行表征,并研究焊料线材对缺陷浓度的影响。此外,测试了涂层的基本力学性能,对测试结果进行定性和定量分析。结果表明,EL-600 HB堆焊涂层总表面的平均缺陷百分数最小,为1.5%。EL-600 HB堆焊涂层总表面的平均缺陷百分数最大,为7.2%。获得了堆焊涂层的化学成分。

On complete convergence in Marcinkiewicz-Zygmund type SLLN for random variables

We consider a generalization of Baum-Katz theorem for random variables satisfying some cover conditions.Consequently,we get the results for many dependent structures,such as END,ϱ^(*)mixing,ϱ^(-)mixing andφ-mixing,etc.

Middle ear reconstruction estimated by recurrence plot technique

Middle ear surgery techniques have enabled to improve hearing destroyed by a disease. Despite huge improvement in instrumentation and techniques the results of hearing improvement surgery are still difficult to predict. This paper presents the results of vibrations measurements in a human middle ear obtained at the Medical University of Lublin. Vibrations of the stapes in the case of the intact ossicular chain, after cement incus rebuilding and incus interpositions are compared each other. In this aim a new approach of ossicles vibrations observation is introduced in order to complete information obtained from classical approach which bases on the transfer function. Measurements of ossicular chain vibrations are performed on fresh human temporal bone specimen using the laser doppler vibrometer. Next, after classical research, the extended analysis with the recurrence plots technique is performed.

A dual-beam piezo-magneto-elastic wake-induced vibration energy harvesting system for high-performance wind energy harvesting

Wind-induced vibration energy harvesting has a great potential for utilizing wind energy to supply power for low-powered devices.To improve the working performance of energy harvesters effectively,a suitable structural design is crucial.This paper proposes a dual-beam piezo-magneto-elastic wake-induced vibration energy harvesting system to enhance the functional performance of aeroelastic energy harvesters in environments with variable wind speeds.The system contains two piezoelectric beams coupled by magnets(forming upstream and downstream energy harvesters),and each beam is attached with a foam cylinder.A corresponding dynamic model is provided,and output characteristics are obtained at different wind speeds.Results and experimental verification indicate that both upstream and downstream energy harvesters can realize efficient energy harvesting.When the wind speed exceeds a certain critical value,the amplitudes of the system’s displacement and voltage are high.The wind speed threshold value is approximately 1.25 m/s.When the wind speed and magnet spacing are 10.2 m/s and 20 mm,respectively,the output power of the system reaches 4.9×10^(−4)W.Moreover,the wind speed threshold value of the proposed system can be adjusted by an equivalent nonlinear restoring force.

Analysis of the Cross-Wedge Rolling Process of Toothed Shafts Made from 2618 Aluminium Alloy

The paper presents the results of a thermo-mechanical analysis of the rolling two stepped shafts.One of the shafts has a toothed step with skew teeth,while the other has a worm winding in the shape of a trapezoidal screw.The shape of the rolling tools resembles that of the tools used in the Roto-Flo rolling method;yet unlike in Roto-Flo,the shafts are hot-rolled and no centres are used to stabilize the position of the workpiece during the forming process.For the calculations made with use of the DEFORM-3D process simulation system it has been assumed that the rolled shafts are made from 2618 aluminium alloy.As a result of the calculations made,it has been found that the toothed stepped shafts can be formed in one pass by means of the cross rolling process.Additionally,the temperature and strain distribution in the rolled product have been determined as well as some data concerning the forces which are necessary for the rolling process have been obtained.

Cross-Wedge Rolling of Shafts With an Eccentric Step

A new concept for forming eccentric shafts on the basis of the cross-wedge rolling （CWR） process was presented. This concept was based on the application of special guides, which, by acting on a billet, lead to its controlled movement in the vertical direction. This movement made possible eccentric cutting of tools into the billet. FEM calculations and experimental rolling tests clearly confirmed the effectiveness of the proposed forming method.

On the stochastic response regimes of a tristable viscoelastic isolation system under delayed feedback control

In this paper,a tristable viscoelastic isolation system with stochastic excitation under both displacement and velocity delayed feedback control is considered.Firstly,the theoretical expressions of the mean first-passage time(MFPT)to measure the activated escape between different potential wells are derived.Induced nonlinear transition dynamics due to the noise and time delays are mainly discussed.It is found that the delay-induced behaviours affect the transitions between the equilibrium points of the system,the corresponding phenomenon of the delay-enhanced stability is observed.In this respect,the existence of the maxima of the MFPT1 and the MFPT2 is found in one period.Meanwhile,the MFPT1 and the MFPT2 show the monotonic behaviour with the increase of the noise intensity.Additionally,the stationary probability density of the amplitude and the stationary mean amplitude are derived.The influence regimes of the system parameters on both stationary probability density of the amplitude and the stationary mean amplitude are explored.This paper establishes the relationship between system parameters and dynamical properties of the tristable viscoelastic isolation system.This provides a fundamental guidance for the optimization of the viscoelastic isolation by utilizing the technique of delayed feedback control.

The zero-dimensional model of the scavenging process in the opposed-piston two-stroke aircraft diesel engine

The analysis of the scavenging process in two-stroke engines is important in terms of achieved performance and emission of toxic substances.The amount of mass of air used for the scavenging process and the amount mass of gas retained in the cylinder affect engine effi-ciency.When designing two-stroke engines,the most efficient charge exchange process defined by the scavenging efficiency parameter is desirable.The process of charge exchange in a twostroke opposed-piston aircraft diesel engine based on the assumed scavenging model was analyzed in this work.The charge exchange process was performed by a mechanical centrifugal compressor.A zero-dimensional engine model created in the AVL BOOST program was used for the research.The simulation tests were performed for the selected operating conditions,i.e.maximum continuous power.The analysis of the charge exchange process was accompanied by obtaining the basic engine operating parameters from the simulation calculations.