bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation on low temperature characteristics of SBS/CR modified asphalt binder under different aging conditions
Authors: Zhou Jie , Chen Xianhua , Xu Gang , Zhang Hanyu
Published: October 2019

This study discussed the low temperature performance of styrene–butadiene–styrene (SBS)/crumb rubber (CR) modified asphalt under different aging process. The bending beam rheometer (BBR) test was conducted to compare the low temperature performance of SBS and SBS/CR modified asphalt at three different temperatures. The continuous low service temperature of two modified asphalt binders was calculated based on the ASTM method. The simple fractional viscoelastic model was implemented to better describe the creep behaviour of asphalt at low temperatures from the BBR test results. The damping ratio and dissipated energy ratio were also derived from the simple fractional model to assess the low temperature performance of asphalt from the aspect of energy. The analysis results showed that adding CR to SBS modified asphalt was beneficial to reduce the low service temperature and increase the values of damping ratio and dissipated energy ratio before and after the aging process. It has been proved that the low temperature performance of SBS/CR modified asphalt is much better than that of SBS modified asphalt under different aging conditions.
The Effect of Dynamic Vulcanization on the Mechanical and Thermal Properties of Stereocomplex PLLA/PDLA/rubber Blends
Authors: Phattarateera S , Pattamaprom C
Published: October 2019

This study investigated the influence of dynamic vulcanization of sterecomplex PLA/PDLA (ST) containing various types of rubbers by using dicumyl peroxide (DCP) as a vulcanizing agent. In this work, natural rubber (NR), isoprene rubber (IR), silicone rubber (SI), acrylic rubber (AR), thermoplastic copolyester (TPE) and thermoplastic polyurethane (TPU) were selected. Here, 5 wt% of PDLA, 15 wt% of rubber and 2 wt% DCP as an initiator were melt-blended with PLA in an internal mixer at 180 0C and 50 rpm. It was found that the addition of DCP in (NR and IR) led to a significantly increase in the impact strength and % elongation at break. On the other hand, for the rubbers that do not have double bonds in the main chain (SI, AR, TPE and TPU), the addition of DCP led to a decrease in impact strength and % elongation at break compare to the case without DCP due to the lack of double bonds to react with DCP. For the effect of DCP on the rubber dispersion, it was found that the addition of DCP on the NR and IR could improve the interface compatibility of the rubber and PLA leading to smaller average rubber domain sizes than without DCP. For other types of rubbers, the average rubber domain sizes were bigger with poorer interface compatibility than without DCP. For the effect of DCP on the crystallinity, it was found that the addition of DCP could increase the crystal density and could consequently reduce the crystal sizes of the ST/rubber blends.
Effect of freeze-thaw cycling on fatigue behaviour in concrete
Authors: Boyd Andrew J. , Leone Andrea
Published: October 2019

Freeze-thaw damage is a deterioration mechanism caused when saturated concrete is exposed to temperature variations that cycle above and below its freezing point. The expansion of water in the concrete pore space due to freezing can lead to internal pressures that induce cracking, thus expediting the deterioration process through freeze-thaw cycles. The purpose of this investigation was is to evaluate the effect of freeze-thaw deterioration on the tensile fatigue life of air-entrained concrete at early stages of deterioration. Concrete cylinders were prepared with 0.45 and 0.65 water to cement ratios (W/C), then cured for 28 days before being subjected to the freeze-thaw cycling. After 0, 25 and 50 freeze-thaw cycles, the pressure tension (PT) test was used to induce tensile fatigue loading cycles until failure. The PT was capable of determining the decrease in fatigue life, represented as the number of cycles to failure, of the concretes when subjected to pure cyclical tensile loading after having first been exposed to freezing and thawing cycles. The results indicated that even though the ultimate static tensile strength of the specimens did not vary significantly due to the freeze-thaw cycles, the residual fatigue properties were degraded. UPV monitoring was able to determine the increase in internal damage, as the UPV of the specimens decreased with continued freeze-thaw cycling. It was shown that freeze-thaw deterioration reduces the ability of concrete to withstand cyclic loading, even at early stages prior to a decrease in static tensile strength.
Dynamic compliances of rigid foundation on layered poroelastic soils
Authors: Keawsawasvong Suraparb , Senjuntichai Teerapong , Plangmal Rawiphas
Published: October 2019

Dynamic interaction between a rigid foundation and layered poroelastic soils is studied in this paper. The foundation is subjected to time-harmonic vertical horizontal and moment loading, and bonded to a layered poroelastic half-space. The interaction problem is formulated by employing a discretization technique based on the rigid body displacement boundary conditions at the foundation-soil contact surface and the displacement influence functions of a layered poroelastic half-space. The discretization method used in this paper yields a flexibility equation system for the contact traction at the foundation-soil contact area. Comparison with existing solution for a rigid square foundation on an elastic half-space is presented to verify the accuracy of the present scheme. Selected numerical results for compliances of rigid square foundations are presented to portray the influence of poroelastic effects on the dynamic interaction problem.
Material image segmentation based on feature similarity and non-spherical clustering
Authors: Wang Huan
Published: October 2019

The microstructure of the material determines its physical and chemical properties. Although image segmentation and target extraction algorithms have advanced rapidly in recent years, few segmentation algorithms for material images have emerged. By analyzing the characteristics of material images, A new image segmentation method based on feature similarity and non-spherical clustering is proposed in this paper. First, the central pixels of the region are selected according to the feature similarity, and secondly, the attribution of the remaining pixels or the non-region central points are determined by the non-spherical clustering method. In this paper, ceramic images are used as experimental materials. The results show that the proposed method achieves satisfactory segmentation effect and provides some help for subsequent image-based material analysis.
Properties of Kenaf Fibers/Epoxy Biocomposites: Flexural Strength and Impact Strength
Authors: Suherman Hendra , Azwar Edri , Duskiardi  , Yovial  , Septe Edi
Published: October 2019

Kenaf is a non-woody plant, which has high potential fiber to be used as polymer matrix reinforcement. Different compositions of kenaf fiber as bio reinforcing material at different fabrication process parameters will produce different biocomposite properties. This study uses kenaf fibers in the composition of 10, 20, and 30 wt.% as reinforcing material. Kenaf fiber and epoxy resin were mixed based on predetermined compositions, stirred using a mechanical stirrer at 200 rpm for 10 minutes. Then the mixture is poured into a mold and placed on a hot press machine. Pressure of 50 kg/mm2 for 30 minutes at 150°C is used to produce kenaf fiber/epoxy biocomposite. The result showed that the increasing of kenaf fiber content in the matrix is succeeded to increase the flexural and impact strength of the biocomposite kenaf fiber/epoxy produced. The highest flexural strength (136 MPa ) and highest impact strength (180 KJ/m2) were obtained at a composition of 30 wt.% Kenaf fiber.
Research of Concrete Durability in Compressed Elements with Different Types of Confinement Reinforcements
Authors: Krishan Anatoly L. , Chernyshova Elvira P. , Chernyshov Vladislav E.
Published: October 2019

The paper presents experimental research of short center compressed elements with circular cross section in different types of concrete confinement reinforcements, namely by introducing glass fiber-reinforced shell, steel spiral and by using these two types together was conducted. The results of the conducted experiments show the positive influence of both outer glass fiber-reinforced shell and spiral reinforcements on the durability of such elements. The highest degree of durability was achieved when two types of confinement reinforcements were used simultaneously. The durability of the concrete core of the samples made from class C40 concrete increased by 3.25 times and equaled 135 MPa. In case of the initial class C80 concrete the effect of confinement reinforcements was considerably smaller but nevertheless it was high enough. The durability of the concrete core increased by 2 times. The introduction of two types of confinement reinforcements considerably improved the deformability of compressed elements. The maximum recorded values of contraction longitudinal strain of the samples made of high endurance concrete were about 1%, and in case of concrete class C40 they were 2.4%. Such high level of deformability in compressed elements will help to effectively use high durability longitudinal reinforcements with the compression yield strength up to 2000 MPa and higher in them.
Synthesis of hydrophilic silica nanoparticle and its application as self-cleaning coating for solar cell panels
Authors: Boonsong S , Sowasod N , Muangnapoh T , Wongchaipanich J , Jarunsrirat W , Tanthapanichakoon W
Published: October 2019

In past decades, nanotechnology has attracted much attention among researchers and industries due to its high potential of adding significant values to the original materials. Thin film coating with nanomaterial can provide new properties and enhance performances of pristine surfaces for certain applications. In this research, we investigated the development of superhydrophilic self-cleaning coatings for solar panels using colloidal silica nanoparticles. The coatings consist of colloidal silica nanoparticles with the average size of 30 nm, sodium dihydrogen phosphate and boric acid under various formulations. The coatings can be applied by simple painting or fine spraying. The light transmittance of the coated samples was characterized by UV–visible spectrophotometer. The water contact angle (WCA) was measured by a contact angle instrument. It was observed that the optimum weight ratio of silica nanoparticles : sodium dihydrogen phosphate : boric acid was 22:1:1 with contact angle of 1.83° and transmittance of 65%.
Effect of curing temperature and particle size distribution on unconfined compressive strength of raw and treated fly ash-lime modified phosphogypsum waste
Authors: Mashifana T , Okonta F , Ntuli F
Published: October 2019

The Voluminous quantity of phosphogypsum waste is generated by phosphoric acid manufacturing industry and end up being landfilled, resulting into environmental pollution. This study was done to determine applications for raw and treated waste phosphogypsum in building and construction, to determine the best conditions to produce the final product. Two readily available wastes namely phosphogypsum and fly ash were used and blended with hydrated lime. Best strengths was obtained from a mixture of phosphogypsum-lime-fly ash specimens were at elevated temperatures. The strengths obtained at the temperature of 80°C were above the 3.5 MPa permissible strength for building masonry with unconfined compressive strength up to 4.8 MPa. At lower temperature of 40°C the optimum strength obtained was at the minimal phosphogypsum content of 30%. The optimum strength was achieved at the PG content of 50% for raw PG and 60% for treated phosphogypsum. The strengths obtained for the treated phosphogypsum were lower than the minimum permissible load bearing strength due to the non-uniform particles distribution and the presence of impurities and forces of adhesion between citric acid and phosphogypsum. Increasing the curing temperature also reduced the radionuclides initially present in the raw PG without any prior treatment.
Stabilization of gold mine tailings: The effect of hydrated lime on the unconfined compressive strength
Authors: Mashifana T , Sithole N , Mkhonto E
Published: October 2019

Stabilization of gold mine tailings for application in the building and construction industry, provides a significant solution to the shortage of building and construction materials for the country’s growing population. The use of gold mine tailings in the production of building blocks / bricks, is examined in this study. The tailings used in the study were characterized by having an optimum moisture content (OMC) of 14.92% and a maximum dry density (MDD) of 1 757 kg/m3. The specimens were cured at a temperature of 80oC and hydrated lime was added as a stabilizing additive to enhance the chemical and geotechnical properties of the material. The use of lime as a stabilizing additive was successful in increasing the unconfined compressive strength (UCS) of the material. UCS was improved from 0.04MPa to a maximum strength of 3.02MPa. As far as the UCS is concerned, the optimum tailing: lime was obtained at a ratio of 70:30 and the produced material is suitable as masonry.
Silicon and aluminium leaching kinetics from acidic gold mine tailings
Authors: Falayi T , Mashifana T , Ntuli F
Published: October 2019

Si and Al were leached from gold mine tailings (GMT) in order to determine if the GMT could be used as precursors for the synthesis of geopolymers. Possible synthesis of geopolymers from GMT would help reduce their potential pollution effects through heavy metal immobilisations. The effect of type of alkali (NaOH/KOH), alkali concentration, temperature, milling and calcination of GMT and solid liquid ratio (S/L) on the leaching of Si and Al was investigated. The optimum conditions were 10 M KOH, S/L of 0.5% m/v and a leaching temperature of 95°C. The leaching obeyed the shrinking core model with the surface chemical reaction being the controlling step. The leaching of Si was linked to the Al leaching since the Si/Al ratio of the leachate was around 2 irrespective of leaching conditions. KOH yielded more Si and Al. as compared to NaOH, with 54.7 and 26.7 Si and Al leached respectively from as received GMT. Calcination at 900°C resulted in 18% and 22 % increase in Si and Al yield respectively for KOH based leaching. The successful leaching of Si and Al from GMT using KOH provides opportunities for the geopolymerisation of GMT thereby allowing the minimisation of their pollution effects.
Durability of desilicated fly ash lime composites
Authors: Falayi T , Sithole N.T , Okonta F
Published: October 2019

Remediation of residual fly ash from coal fired electric power plants is beneficial to the environment. The chemical, physical, geotechnical and radiological properties of desilicated fly ash (DFA) were investigated. The DFA: lime ratio of 70:30 composite was found to have an average UCS of 8.8 MPa showing 19.5% water absorption after a 24 h soak with a corresponding 23.5% reduction in UCS. The composite was found to meet the minimum UCS requirements after 8 wet and dry cycles but with failure at 10 cycles. The composite was found not to be resistant to acid attack at pH 2 and hence could not be used in the vicinity where landfill leachate may come into contact with the composite. The composite had relative stability against acid rain and normal rain. The composite met the minimum requirement of ASTM C34-13, and thus provide an opportunity for high volume utilization of the residual ash for construction of load bearing walls.
Reuse of pulverized fired clay brick wastes as cement substitute in mortar for sustainable construction
Authors: Olofinnade Oluwarotimi , Ede Anthony , Ndambuki Julius , Omole David , Francis Precious , Chigere Cynthia , Oyeyemi Kehinde
Published: October 2019

Recently, there has been an increase on the use of waste materials for development of new materials for construction. This is due to the need for sustainable development which emphasizes on waste reduction, reduction of greenhouse gases (GHG), greener clean environment and conservation of raw resources. This study examines the appropriateness of clay brick waste in powder form as a suitable material for partial substitute of cement in mortar. The clay bricks were obtained as generated waste materials from a brick producing factory in Lagos metropolis and then subjected to grinding. Tests which include; specific gravity, particle size distribution, x-ray fluorescence and scanning electron microscopy were carried out on the pulverized clay brick material (CBP). Further, it is used to partially replace cement in mortar at replacement percentage of 0, 5, 10, 20, 25, 30, 40 and 50% using a mix ratio of 1: 2.75 at 0.45 water-cement ratio. Compressive strength and strength activity index tests were carried out on the cube specimens after days of curing. The obtained results clearly indicate that the pulverized clay brick is an amorphous material and contains similar chemical oxide compounds of a pozzolana. Furthermore, it was observed that the compressive strength of the mortar was further improve at an optimum value of 20% cement replacement with clay brick powder compared to the control mortar. Therefore it implies that generated clay brick wastes can be pulverized and used as pozzolanic admixture in mortar production instead of discriminate dumping in landfill.
Oil Well Cement for high temperature-A review
Authors: Munjal Pankaj , Hau Kong Kian , Prabhakar Abhinav , Arthur Cheng Chuen Hon
Published: October 2019

Oil well cement (OWC) are widely used in oil industry both in exploration and in production of oil and gas. The purpose of OWC is to seal the annular space between metal casing and walls of a borehole. OWC has other application such as grouting and repair of offshore structure, and in cementing of other wells likes as water, waste disposal, geothermal, injection or storage. There are numerous problems such as high temperature and high pressure in the downhole condition of oil well. OWC slurry undergoes a reduction in strength (strength retrogression) with time when exposed to high temperature and high pressure. This paper reviews the OWC and its classifications, hydration process at ambient and higher temperature. Moreover, this study provides a comprehensive insight on anti-strength retrogression additives, which can potentially be use with OWC at high temperature and pressure.
Utilization of fly ash: basic oxygen furnace slag as a raw material in geopolymerization
Authors: Mashifana T , Sithole N
Published: October 2019

The aim of this project was to develop a basic oxygen furnace slag (BOFS) and fly ash (FA) based geopolymer. The developed geopolymer were required to have strength to withstand hydraulic load. In respect to BOFS and FA, there are two main ways in which they can be handled following the best practices of conserving the environment. The two are disposal and utilisation, the disposal thereof is a problem because it increases the amount of FA annually since they are not consumed completely yearly. Results also showed that wastes beneficiate FA and BOFS can be utilised for other applications and this will reduce these wastes in the landfills. The development of the geopolymer to investigate the optimum conditions to enhance strength has resulted in a 20 % FA mass blend ratio, 9 M concentration of sodium hydroxide, 20 % liquids solid-liquid ratio and 80 °C curing temperature. The addition of hydrogen peroxide to the geopolymer increased the porosity of the geopolymer.
Applications of UAS-obtained thermal images for vegetation coverage ratio monitoring of mudstone areas
Authors: Chen Chien-Yuan , Lin Chai-Li
Published: October 2019

Soil vegetation coverage is a crucial factor for those wishing to protect naked slopes. Thermal imaging enables monitoring of the changes in infrared temperature of a slope surface and calculating the vegetation coverage ratio (VCR). The VCR is an efficient method for determining infrared temperature changes in different slope lands, which include regions exposed to sunlight, vegetation areas, and shaded areas. The thermal images capture the infrared temperature distribution, boundary of vegetation of temperature, and barren vegetation areas. The VCR can be subsequently calculated. In this study, thermal images were obtained using an unmanned aircraft system (UAS) according to airline planning, frame size of an image, and overlapping of lateral and front images for taking pictures. Moreover, 3D images can compare the VCR by calculating the aggregation of the study area and vegetation area. A satisfactory agreement was obtained between the infrared temperature obtained through thermal imaging and the VCR. Thermal imaging can thus be used to monitor changes in the VCR of mudstone. Moreover, a 3D topographic map was created using the UAS-obtained images to overlap with the thermal images.
Research on Wire-Broken Monitoring of Bridge cable based on Acoustic Emission technique
Authors: Zhu Zhiqin , Wang Dawei , Liu Chen , Wang Bingjian
Published: October 2019

Acoustic emission signals generated by broken prestressed steel strand of cable can transmit up to 29.5 meters without maintaining significant attenuation of the amplitude. Therefore, the installation of a few acoustic emission sensors can comprehensively monitor the damage of the entire prestressed steel strand. Thereby, the detection of unknown defects is realized, and the structural health status can be quantitatively and quantitatively evaluated. In this paper, the acoustic emission technology is used to monitor the damage and fracture of prestressed steel strand under over tension. The acoustic emission technology is used to test the broken wires of cable of a concrete-filled steel tubular arch bridge. The correlation of the broken wires test results of the bridge is qualitatively analysed, including the stress state of the cable, the location of the measuring points and whether there is a PVC sheath at the measuring points. Therefore, a safe, reliable and efficient method is sought to monitor the damage status of the in-service cable-supported bridge.
Exploration of key commercial space design indicators
Authors: Lin Mu-Fa , Perng Yeng-Horng
Published: October 2019

The designs of commercial spaces change with time. This study explored competitive factors that affect commercial space development by using the Delphic hierarchy process with the aim of enhancing the overall performance of commercial spaces in a highly competitive retail market. The findings provide key factors that can be used by shopping center operators when selecting commercial space designers. Competitiveness indices were proposed by referring to the literature and conducting interviews with industry experts, scholars, and practitioners. Subsequently, hierarchy structures and indices were established, and relative weights were allocated to each dimension and index. Finally, the evaluation data were calculated and consistency tests were conducted. This study adopted 18 performance indicators to demonstrate the validity of the overall competitiveness indicators, which were verified as possessing high validity.
Effective use of a helicopter with a Bambi bucket firefighting system in Bulgaria
Authors: Seyzinski D T , Georgiev I , Panayotov H P , Penchev S I
Published: October 2019

The present paper studies the effectiveness of the use of the Mi-17 helicopter with a Bambi bucket firefighting system in operations against mountain and forest fires in the Republic of Bulgaria. It makes an analysis of the conditions under which it is used, on the basis of numerous publications about theoretical and experimental studies, including ones aimed at increasing the efficiency of using helicopters with other external hanging firefighting systems. The preparation and conduct of flying experiments with a Bambi bucket system have been made. They take into account the specifics of this system, the characteristics of the firefighting methods used in the Republic of Bulgaria, and the of country specific external factors. On the basis of the results of these studies, and by taking into consideration the flight safety requirements, recommendations have been made to improve the effectiveness of using a Bambi bucket firefighting system in Bulgaria.
Optimal three-loop cascade PI-P-PI controller for electro-hydraulic power steering system
Authors: Kralev Jordan , Mitov Alexander , Slavov Tsonyo , Angelov Ilcho
Published: October 2019

The present paper presents an optimally tuned proportional integral differential (PID) system which calculates the driving signal for the switching valves in order to achieve steering trajectory tracking. The designed cascade control algorithm consists of three PID controllers respectively for the spool valve position, for the effective flow rate and for the steering cylinder position. The stages of the cascade control algorithm synthesis are presented. The goals of control algorithm are to achieve fast transients with minimal overshot and steady state error. Controllers’ are tuned consequently by starting from the innermost loop based on an identified single-input multiple output (SIMO) model of the steering system by optimization algorithm with a quadratic cost. After one of the controllers is successfully tuned the model of the corresponding closed loop system is approximated and employed in the optimization procedure for the next control loop from the cascade system. The developed control algorithm is programmed into a specialized vehicle microcontroller and tested on a steering system test bench in the laboratory.
Study of the stresses in the front suspension components of a car passing over speed breakers
Authors: Georgiev Z A , Kunchev L P
Published: October 2019

To reduce the speed of vehicles before pedestrian crossings or as a warning for lowering the speed, vertical deflection devices or road profiles are placed transversely to the direction of travel. The type of profiles is different – speed bumps and humps with different height and length. Some of the profiles have the task of alerting the driver of changing conditions or potential danger - such are the rumble strips, while others aim to force the driving speed below 30 km/h. The amplitudes of the second profiles are considerably larger than those of the first and can cause significant stresses in the front suspension elements and its connections. The purpose of the study is to obtain information on the load on the front suspension components when passing over speed breakers.
Neural model of projecting flexural strength of cement concrete intended for airfield pavements
Authors: Linek Małgorzata
Published: October 2019

This work present to the mathematical model in the form of Artificial Neural Network (ANN), intended for projecting concrete flexural strength. Input data was classified according to the type of component material and its content in concrete mix (cement contents, coarse aggregate, fine aggregate, water and admixtures). In order to determine mathematical model, a multilayer, one-way perceptron network was used, recursion network with sigmoidal neurons. The model assumes that neurons are gathered in some layers (one input layer, hidden layers and one output layer). The conducted cross-section of the impact of variable parameters values (learning constant α and momentum values η) on the accuracy of representation of flexural strength was analyses. Assessment criterion was assumed as consideration the lowest mistake level and 100% compliance. According to the obtained results ANN was assumed to be the best representing network for constant value of momentum 0.3, learning constant of 0.04 and 9 neurons in a hidden layer. Very good coincidence of component models with experiment results was achieved. At testing stage, the coincidence was achieved at the level of 99.25%, in case of the assumed network structure. During model verification by means of experimental results, the average coincidence was 99.68%.
Rationalization of cross-sections of the composite reinforced concrete span structure of bridges with a monolithic reinforced concrete roadway slab
Authors: Vatulia G L , Lobiak O V , Deryzemlia S V , Verevicheva M A , Orel Ye F
Published: October 2019

The article presents the developed rationalization technique of composite steel reinforced concrete sections with steel open section beams based on the criterion of equal strength of the section elements that are extremely distant from the neutral line. Algorithms for search for geometric parameters of a composite section limited to a certain range of values are implemented to achieve the equal strength condition. The dimensions of the individual elements which are parts of the cross-section are obtained from the condition of the constant ratio of the distances from the neutral axis to the extreme concrete and steel fibers. The numerical methods were used for calculation of continuous three-span composite reinforce concrete bridge. The technique implements the steps of bridge construction, taking into account the contact yield of the composite section, the redistribution of forces between the elements, and the effect of elastic-plastic and rheological properties of materials. The generalized kinetic curve was utilized for evaluation of concrete creep together with the phenomenological equations for the development of deformations based on a colloid-chemical representation of the mechanism for long-term concrete deformation. The proposed methodology is implemented in the LIRA-SAPR software package based on the Building Information Model Technology (BIM) and the Finite Element Method (FEM).
Multicriterial synthesis of the control law for a semi-active spatial model of the vehicle suspension
Authors: Genov Julian
Published: October 2019

This article explores the task for the multicriterial synthesis of the control-law from the type Linear Quadratic Regulator (LQR), for a semi-active vehicle suspension. It is consists of obtaining the optimal compromise between the requirements for sufficient ride comfort and vehicle stability on the road pavement. The relevant object-functions are defined. It is proposed an algorithm for a multicriterial hierarchical approach for identifying in the Pareto’s set of solutions, this solution that realizes the optimal compromise in the sense of John Nash’s sustained strategy from the antagonistic games theory. Based on this approach, a new algorithm for the synthesis of LQR is proposed, combined with a compensator, in which the weight matrices being the subject of optimization. This synthesis was applied for a spatial model of a semi-active suspension of a vehicle.
Economic aspects of using hydrogen in compression ignition engine operating on gas-diesel cycle
Authors: Dimitrov E , Pantchev S , Michaylov Ph , Peychev M
Published: October 2019

The article gives an overview of the economic aspects of a single-cylinder internal combustion engine dual fuel operation with diesel fuel and hydrogen. The engine operating costs are calculated. Two separate cases are investigated. The first case is at constant engine speed – 1500 rpm, constant engine power (1.5 kW) and variable hydrogen mass fraction in the total fuel mass (from 0 to 50%) and the second case is at constant engine speed – (1500 and 2000 rpm), constant hydrogen mass fraction in the total fuel mass (10%) and variable engine power (1 to 4 kW). The following parameters (as a function of the corresponding variable) are determined for both cases: expenses for hydrogen and diesel fuel (in €;/hour), price of the energy obtained at the engine crankshaft (in €;/kWh), expenses for the CO2 emissions emitted by the engine (in €;/hour). The weighted average of the fuel mixture price (in €;/kg) is also determined for the first case. The calculations are made using average fuel prices in Germany for April 2019. A predominant growth in the operating costs is observed as a function of the growing hydrogen mass fraction and increasing engine power. A significant reduction in the price of CO2 emissions at constant engine power and growing hydrogen mass fraction is observed due to the lower exhaust gas toxicity.
Vibroacoustic analysis of marine engine supplied with mixture of fuels
Authors: Wróbel Radosław , Andrych - Zalewska Monika , Tkaczyk Marcin , Fryda Szymon , Dimitrov Radostin
Published: October 2019

The main purpose of this paper is to obtain the differences in the vibrations of engine (Doosan MDT196TI) which was powered using two different fuel mixtures – liquefied natural gas with diesel pilot and diesel only. LNG and diesel oil differ in combustion temperature, density, and cetane number; the combustion process of various fuels proceeds differently, so it has an impact on the generated vibroacoustic vibrations (vibrations have a direct impact on the degree of machine degradation). In the research, the diagnostic system is based on piezoelectric accelerometers and Digital Signal Processing operations (windowing, Fast Fourier Transform). In the conclusions section the obtained results are analysed, indicating how the tested fuels have an effect on vibrations.
Comparative analysis of the results of theoretical and experimental studies of freight wagon Sdggmrss-twin
Authors: Stoilov V , Simić G , Purgić S , Milković D , Slavchev S , Radulović S , Maznichki V
Published: October 2019

This paper presents a comparative analysis based on the results from static strength calculation of wagon body, series Sdggmrss-twin, and on the results from the real wagon test. The verification of results from calculations and tests and their comparison was mandatory for client’s commissioning of the wagon by notified body. Calculations based on the finite elements method were carried out in the Department of Railway Engineering at Technical University of Sofia. Experimental studies on real wagon construction were conducted at the facilities of Bulgarian National Transport Research Institute by testing team from Laboratory of rail vehicles at University of Belgrade. It was found that the obtained static stress results are similar, which proves that the proposed models are appropriate and they can help to solve a wide range of issues, for example those related to lightweight design of railway vehicles.
Development of a repair technology for locomotive units on the basis of the theory of decision
Authors: Puzyr V , Datsun Y , Obozny O , Pyvo V
Published: October 2019

The operative condition of locomotives is maintained by the existing repair system; it consists of the following elements: strategy, organization and technology. This repair technology for units and aggregates is based on disassembling and elimination of defects, and it can be inappropriate. The actual technical condition of the nodes requires an individual approach in determining the volume and content of technological impact during the repair process. Therefore, the purpose of this work is to research the task of developing a repair technology for locomotive units, depending on their actual technical condition. As far as probability distribution functions of the operating condition of units are known, a repair technology is chosen under risky conditions. Therefore, the decision-finding problem is framed in the theory of decision terms. The analysis of the decision tree of the choice of repair technology for fuel injectors of a diesel locomotive demonstrated that at least four variants of technologies (strategies) were possible. Operational costs were taken as the evaluation criterion for the technological process. The pay-off matrix obtained does not have a saddle point; therefore, the problem of choice of the technology cannot be solved only strategically. It substantiates a need to use flexible, adaptive repair technologies which consider the actual technical state of each unit. For a known distribution of states for fuel injectors, the greatest gain with minimum risks is the repair technology of dismantling and reseating the worn-out parts. Application of the described approach at locomotive repair enterprises will allow for improvement of the quality of repair and reduction of costs.
Determining traffic potential as an important part of sustainable railway passenger transport
Authors: Dedík Milan , Kendra Martin , Čechovič Tomáš , Vojtek Martin
Published: October 2019

The main goal of EU transport policy in passenger transportation is to support public passenger transport and railway transport as a key transport mode, to know actual transport needs and to determine traffic potential properly. The paper considers particular current problems of public passenger transport, especially railway passenger transport. It proposes the basics of a methodical process that should increase its efficiency, attractiveness, a better image for the traveling public, but especially the increase of transport performance. A very important part of the methodical process is determining traffic potential. Particular methods of determining it are described and a proposal of a new methodology is included. The main aim of the methodology is to determine the value of the total traffic potential coefficient Kp. This value can be calculated using the proposed formula. It is possible to fit the values of the factors affecting traffic potential into the formula. As a result, there is practical application of the proposed methodology on real railway lines in Slovakia.
Network model of passenger railway rolling stock scheduling
Authors: Todorova Mirena Mironova
Published: October 2019

Passenger rolling stock scheduling to the passenger train timetable is based on the same type and number of carriages, which is the standard way of passenger trainset assignment. The possibility of train scheduling with a single carriage, a group of carriages or a railcar is topical issue for each carrier engaged in rail passenger transport in order to reduce the required rolling stock fleet. The paper presents an original network model developed for rolling stock scheduling for trainsets. The model makes possible to determine the optimum distribution of rolling stock in trainsets minimizing downtime at stations through the out-of-kilter algorithm. The model developed is applied to the scheduling of trainsets in part of the railway network in Bulgaria served by BDZ Passenger Transport Enterprise at the Plovdiv region. The use of the model allows to save passenger rolling stock and increases the efficiency of passenger rolling stock operation.
Martensitic transformations in VO2 films
Authors: Urinov X O , Jumanov X A , Amonov A K , Xidirov A M , Kilichov J R , Nurmurodov J X , Jumaboyev T A
Published: October 2019

Martensitic transformation is considered to be non-diffusive since the atoms in the transition are moved to a distance of the order of interatomic, and neighboring atoms in the initial phase remain adjacent and in the new one, only their position changes. In this paper, for the first time, an experimental study of the phase transition metal-dielectric (FPMD) in thin films of vanadium dioxide is accompanied by a structural transition of martensitic type, so this material is a convenient model object that allows you to clearly identify both the processes of defect formation and their influence on its physical properties in the vicinity of the phase transition point. The obtained results are naturally associated with the effect of adhesion and epitaxy on the phase transition, which can be reduced to the contribution to the energy balance of the component σ/d, where σ is the density of the surface energy; d is the film thickness. Physically, this may mean that since the growth of films occurs at a temperature above the FPMD temperature, the orientation of the crystal axes of the high-temperature tetragonal phase is stabilized by epitaxial forces from the substrate side, and this makes it difficult to reconstruct the crystal structure during the phase transition. Phase stabilization in thin layers due to surface effects is a common phenomenon in the physics of thin films.
Workstations Industry 4.0 for instrument manufacturing
Authors: Zakoldaev D A , Korobeynikov A G , Shukalov A V , Zharinov I O
Published: October 2019

The actual task is to project the structure of operator automatic work place in the Industry 4.0 smart factory. The Industry 4.0 smart factory is a new type of production company. Smart factories are oriented to manufacture item designing components in automatic mode. The key technologies of humanless and paperless production are cloud technologies, industrial Internet of things, sensors technologies and others. A principle is given how to construct automatizing work place in existing production companies of the Industry 3.0. There is a functional scheme of the Industry 3.0 production company automatized work place. It is clear that implementation of new informative technologies influence significantly the structure of an operator automatized work place in production. The proposed functional scheme of the automatized work place is for the Industry 4.0 smart factory.
Using states with a large photon number variance to increase quantum Fisher information in single-mode phase estimation
Authors: Lee Changhyoup , Oh Changhun , Jeong Hyunseok , Rockstuhl Carsten , Lee Su-Yong
Published: October 2019

When estimating the phase of a single mode, the quantum Fisher information for a pure probe state is proportional to the photon number variance of the probe state. In this work, we point out particular states that offer photon number distributions exhibiting a large variance, which would help to improve the local estimation precision. These theoretical examples are expected to stimulate the community to put more attention to those states that we found, and to work towards their experimental realization and usage in quantum metrology.
What Do Service Users Want from Mental Health Social Work? A Best–Worst Scaling Analysis
Authors: Wilberforce Mark , Abendstern Michele , Batool Saqba , Boland Jennifer , Challis David , Christian John , Hughes Jane , Kinder Phil , Lake-Jones Paul , Mistry Manoj , Pitts Rosa , Roberts Doreen
Published: October 2019

Despite being a profession dedicated to the empowerment of service users, empirical study of mental health social work appears dominated by the perspectives of social workers themselves. What service users value is less often reported. This study, authored by a mix of academics and service users/carers, reports a Best–Worst Scaling analysis of ten social worker ‘qualities’, representing both those highly specialist to social work and those generic to other mental health professionals. Fieldwork was undertaken during 2018 with 144 working-age service users, living at home, in five regions of England. Of specialist social work qualities, service users rated ‘[the social worker] thinks about my whole life, not just my illness’ particularly highly, indicating that person-centred approaches drawing on the social model of mental health are crucial to defining social work. However, service users did not value help accessing other community resources, particularly those who had spent the longest time within mental health services. Continuity of care was the most highly valued of all, although this is arguably a system-level feature of support. The research can assist the profession to promote the added value of their work, focusing on their expertise in person-centred care and the social model of mental health.
Lived Experience: Deaf Professionals’ Stories of Resilience and Risks
Authors: Listman Jason D , Kurz Kim B
Published: October 2019

Navigating a phonocentric and audistic society can be challenging for Deaf people, yet some of them adapt and exhibit resilience. Although there is a plethora of resilience studies, Deaf people’s narratives are largely unexplored. This phenomenological study explored from a Deaf cultural-linguistic lens 10 Deaf professionals who use American Sign Language in the United States and their observation of other Deaf people’s lived experience. The study focused particularly on their experiences in overcoming significant barriers in their lives and the factors that strengthen Deaf people’s resilience. Based on qualitative data gathered from narrative interviews, three main themes emerged from this study: (a) Barriers to Incidental Learning: The Dinner Table Syndrome; (b) Importance of Family Involvement; and (c) Protective Role of the Deaf Community as a Second Family. The stories in this study highlight how Deaf professionals and other Deaf people navigate barriers and manifest resilience.
Left main bronchial sleeve resection with total lung parenchymal preservation: a tailored surgical approach
Authors: Mantovani Sara , Gust Lucile , D’Journo Xavier Benoit , Thomas Pascal Alexandre
Published: October 2019

Bronchial sleeve resection is an uncommon thoracic surgical procedure. Under specific conditions, patients can be selected to undergo a sleeve resection of the main bronchus with complete parenchymal preservation. The left main bronchus is longer than the contralateral bronchus, therefore left endobronchial tumours can be localized at the proximal end of the bronchus or distally, near the secondary carina. Bronchial anastomosis in these 2 situations requires different approaches. We present the surgical technique of left main bronchus resection with complete preservation of lung parenchyma through a hemi-clamshell incision (proximal tumour) or posterolateral thoracotomy (distal tumour).
Rescuing Nationals Abroad Revisited
Authors: Ronzitti Natalino
Published: October 2019

The general rule on the prohibition on use of force in international relations has rendered controversial the cases in which states may lawfully resort to armed force. Even self-defense, which is undoubtedly a lawful action, is the object of contentious interpretations of its precise content and modalities of exercise. Are there lawful instances of recourse to armed action in addition to self-defense and use of force authorized by the United Nations? This is greatly disputed and the controversy also embodies the legality of intervention for rescuing nationals abroad. The latter's lawfulness is the object of this article, which revisits previous work by the author more than 30 years ago, taking into account new state practice, the scarce jurisprudence, the works of the ILC, the relevant UN declarations and international conventions and the opinions of qualified jurists. The main finding is that the practice of intervention for rescuing nationals abroad, once the prerogative of the Western States, now includes actions by other states belonging to different regional groups. The Russian Federation is the most notable example. This article examines the various circumstances in which the necessity for a rescue operation arises and the justifications that may be invoked. It concludes that intervention for rescuing nationals abroad in mortal danger is allowed by a norm of customary international law, which constitutes an autonomous exception to the prohibition of the use of force in international relations.