Track Width Research Articles

Multi-Channel, Actively Shielded, Power Efficient MRI Z-Gradient Cylindrical Coil Design Using Target-Field Method

Gradient coils are essential for MRI where fast and large electrical current pulses are typically applied to conventional, single-channel gradient coils, particularly for high-performance gradient applications. However, these pulses result in significant power losses and heating of the coil. We investigate the design of power-efficient multi-channel Z-gradient coils operating in the conventional mode comparing them to conventional single-channel coils designed using similar dimensions and alike DC performance characteristics. The power-efficiencies of thirteen different two-channel configurations having various section lengths for two different dimensions are analyzed. The current density of each section is approximated by Fourier series expansion where a linear equation relating the desired target field and current density is formulated and then solved. A stream function is derived from the obtained current density and then used to extract the final winding patterns of each section using a particular track width and a specific number of turns. The design process involves optimizing the current driving each channel, the distribution of coil windings, and the section size. Similarly, the performance of three-channel coils is also investigated. Results show that a power dissipation reduction of 17-28% and ~23% can be achieved using two- and three-channel coils, respectively. Moreover, we showed that multi-channel coils may have a slightly better shielding efficiency compared to conventional coils. A new methodology for designing two- and three-channel coils is presented where an advantage in terms of power efficiency can be gained depending on design parameters, coil’s dimensions, number of turns, and other metrics.

Development and Stability Analysis of a Self-propelled High Clearance Multi-utility Vehicle

A self-propelled hydraulically actuated vehicle was developed for field crops of up to 2.0 m in height to carry out different operations like spraying, weeding, harvesting. The vehicle has provision for variable/adjustable ground clearance and track width to suit different spacing and heights of horticultural crops. Gradability, torque, and power required for the vehicle were calculated based on the dimensions of the selected bias ply traction tyre. The centre of gravity of the vehicle was calculated by the weight moment method. Microsoft Excel add-in was used to create a point manipulation programme, and the positions of the standard components were determined through an iterative process. The static load over the rear wheel and front wheel was kept at 60% and 40%, respectively, for design purposes. Analysis of chassis mechanics was done to find out weight transfer and impending stability on level ground as well as longitudinal and lateral slope. In longitudinal slope, the developed vehicle was found to be stable up to 45.19° and 20.68° under static and dynamic conditions, respectively; whereas in lateral slope, the vehicle was stable up to 39.08° and 22.10° under static and dynamic conditions, respectively. The developed vehicle was tested for weeding and spraying of okra and maize crops with an average height of 1.1 m to 1.5 m. The field capacity for the spraying and weeding operations was 1.9 ha.h-1 and 0.16 ha.h-1, respectively. The cost of operation for spraying and weeding was 400 ?.ha-1 and 1,500 ?.ha-1, respectively. Weeding efficiency and plant damage of the weeder were 92.58% and 1.55%, respectively.

Geometrical parameter optimization of planner square-shaped printed spiral coil for efficient wireless power transfer system to biomedical implant application

In this paper, the wireless recharging of pacemaker's battery for biomedical implant is considered. Planner square-shaped printed spiral coils (PSCs) are selected as primary (Tx) and secondary (Rx) coil for wireless power transfer (WPT) system. FEM based simulation method is used to optimize the geometrical parameters of square-shaped PSCs. The receiving coil is embedded inside the biomedical implant. The coil track width (w), pitch(s), thickness (t), number of turns(N1,N2) and outer diameter (Dout) of square-shape PCS's are the key parameters for higher coupling coefficient and quality factors. Using magnetic resonance coupling (MRC) based on Series-Parallel (SP) topology; experiments are carried out in an analytical, simulation, and physical environment for four operating frequencies: 300 kHz, 800 kHz, 6.78 MHz, and 13.56 MHz. Efficiency obtained by analytical and simulation method is higher with frequency. The optimum frequency for recharging the pacemaker battery is 6.78 MHz, which provides an efficiency of 85.51% at 100Ω load and is very close to the maximum theoretical efficiency. Voltage gain obtained by physical method is in close approximation with analytical and simulation methods.

Automated detection of laser track contours for analysis of laser polishing process stability

Laser polishing (LP) is an advanced finishing technology used to improve surface quality through laser remelting of the surface topography. A thorough understanding of the surface topography formation during laser remelting is critically required to monitor, optimize, and control the LP process. For this purpose, a method for automated detection of laser-material interaction contour along a laser track was developed and was used to estimate the stable and unstable conditions of the LP process. Process instabilities can yield to significant variations of the longitudinal surface profiles and the remelted track width along the laser path. The proposed method relies on a first derivative-based determination of the two spatial contour boundaries that delimit the width of the remelted laser track. The developed technique was tested and applied to two experimentally obtained laser tracks under non-stable and stable LP process conditions. This study demonstrates the efficient applicability of the automated contour detection in advanced analysis, monitoring, optimization, and control of the LP process stability.

Автоматизоване проектування друкованих плат у CАПР та їх подальше виготовлення за допомогою CNC-машин

The article presents methods and means of 3D design of printed circuit boards in CAx. Automated placement of elements on the board is implemented by means of API SolidWorks using Visual Studio C#. The API application works by an algorithm that allows you to create a 3D layout of printed circuit boards. Each component of the library contains a conditional graphic notation of the element. With the help of the implemented algorithm, a comprehensive approach is provided, which consists in the fact that already at this stage the preparation of the strategy for tracing the conductors of the future printed circuit board is carried out, the classes of circuits are determined and the necessary technological parameters are set, as well as the data necessary for the preparation of design documentation is generated. After the completion of the work on the input of the scheme, a check is made for the presence of errors and compliance with the specified parameters, and if the test is successful, a list of circuits is generated for transfer to the tracing program. From this moment, any possibility of errors in the subsequent stages of design is excluded. CAD DipTrace was used to trace printed circuit boards and generate g-code. Printed circuit board processing is carried out on a CNC machine - CNC3018 using the Candle program. The printed circuit board tracks are created by forming a groove between the track and the metallized coating of the textolite. With the help of the formed height map, the uniform removal of the metallization layer over the entire area of the textolite is ensured. In addition, holes are drilled for the output elements of the circuit, the printed circuit board is cut along the contour and covered with a layer of tin to prevent oxidation of its metallized coating. The considered CAD methods and tools made it possible to automate the design of the printed circuit board of the FM radio receiver control module. As a result of the performed work, means of automating the design of printed circuit boards were applied and a fully functional printed circuit board with a track width of 0.8 mm was obtained.

Determination of the maximum dangerous width of a rail track on a reinforced concrete base with fasteners of the КБ type, taking into account all influencing factors

Railway track retention standards in Ukraine do not take into account theconstruction of the subrail base, but regulate one for all types maximum dangerous value of the trackwidth, which was changed from 1546 mm to 1548 mm without any justification of scientific researchor explanations of the effects of tolerances the width of the rail track and the wheel track, which ingeneral at that time were not fully investigated but taking into account the emergence anddevelopment of new scientific problems associated with the emergence of intensive lateral wear ofrails and ridges of locomotive and wagon wheels. The deterministic dependences of lateralimpressions of the P65 type rail thread head on the simultaneous influence of vertical and horizontalforces for the newly installed repair profiles of UZ rolling stock on the basis of previously performedexperimental and theoretical studies were investigated. The results allow at this stage of research todetermine and calculate the practical values of the maximum dangerous width of the track, in whichthe subrail base consists of reinforced concrete sleepers and separate rail fasteners, which are usedboth on conventional highways with mixed traffic and on high-speed lines UZ.The article establishes the need to take into account new factors influencing the dangerouswidth of the rail track with intermediate rail fasteners of separate type depending on the load stress of sections and new repair profiles of rolling stock, as well as wear processes of intermediate railfasteners type KБ and its elements on the appearance of elastic backlash in the lateral direction fromthe influence of the guide wheels of the rolling stock. The recommended value of the maximum widthof the rail track for areas where service or emergency braking is applied - 1550 mm, taking intoaccount that the contact of the wheel and the rail is not at a point, but on an ellipse. The establishednorm of the maximum width of a rail track allows to define economic efficiency of introduction in theconditions of operation of a track in curved sections of a track of small radii with limited use of themaximum admissible lateral wear (15 mm) of a head of a rail thread provided that the normal-forcedentry of rolling stock carts.

TRANSPORT LOGISTICS IN A PANDEMIC CONDITIONS

Background. The world economy is undergoing significant changes due to difficult pandemic conditions and quarantine restrictions. Today, logistics companies need to adapt to the new operating conditions in order to overcome the consequences of the pandemic and be competitive in the market of Ukraine and the world. The aim of this scientific article is to analyze the current conditions of multimodal transportation and substantiate the necessary ways to develop transport logistics during the pandemic. Materials and methods. While writing the article the following research methods were used: the method of elementary theoretical analysis and synthesis, the method of deduction, economic and statistical methods, the method of expert evaluation, which revealed the main purpose of the article. Results. Based on the study of the main directions of the National Transport Strategy of Ukraine, the consequences of the development of transport logistics and multimodal transportation have been determined for the country’s economy. An analysis of the state of combined transport in Europe was performed and the main directions of its development were identified, which are relevant for our country. The issues of transport interoperability and its impact on transport and logistics services are considered. The development of transport logistics is directly related to the transition of the railway to a track width of 1435 mm, which will open new opportunities in international traffic and give the opportunity to reach a new level in the field of logistics. Conclusion. The development of transport logistics requires new opportunities and ways to develop this industry. With great export potential and favorable geographical location, Ukraine should integrate into the world system of multimodal transportation by expanding container transportation, which will lead to the development of transport logistics. Today, multimodal transportation has all the necessary legislative documents and support from the state, but obstacles to their development at the international level require significant capital investment.

Experimental testing on the influence of shaft rotary lip seal misalignment for a marine hydro-kinetic turbine

Tidal energy has received considerable attention over the past decade due to its predictability and high power density. The research in the tidal turbine area has concentrated primarily on the improvement of the energy conversion efficiency. In contrast, the testing of the tidal turbine’s mechanical components has received less attention. In particular, the reliable operation of rotary seals is crucial to prevent water ingress into mechanical and electrical components. This paper outlines an experimental test campaign to investigate the effect of shaft misalignment. Both instantaneous temperature and pressure measurements were recorded from two rotary seals. It was shown the temperature inside the aligned seal increased until the seal chamber pressure became equal with the inlet water pressure. The wear on the lip seal rings was examined and the difference found to be between 3.28% and 19.61%. Inspection of the seal liners, showed the presence of strong wiping effects for the misaligned seal with maximum track width differences of between 52.94% and 97.60% being noted. The misaligned seal liner experienced wider wear tracks but were not as deep as the aligned seal with differences of between 37.55% and 103.13% being recorded.

Lateral Stability Performance of Articulated Narrow-Track Tractors

A tractor losing lateral stability starts to rollover. It is a matter of fact that tractor lateral rollover accidents are one of the most frequent causes of death and injuries for farmers. Consequently, tractors are fitted with a specific protective structure to minimize the consequences for the driver during the rollover (ROPS). The narrow-track tractor, designed to operate in vineyards and orchards, is a tractor category with a very narrow track width and the risk of rollover is higher. The aim of the study was to evaluate the compact narrow-track tractor types commercially available, designed to mount a cantilever engine in the forward position with effects on the Center of Gravity (CoG) because more than 50% of the tractor weight is loaded on the front axle, and, specifically, the articulated narrow-track tractors where the stability is affected by the pivot point connecting the two tractor bodies. As a consequence of the typical tractor design of articulated tractors, during the steering action the line passing through the front and rear tire contact points on the ground changes, influencing the tractor’s stability. The approach of the research was based on reproducing the lateral stability tractor condition by developing a kinematic model, with the goal to virtually simulate the tractor behavior and to calculate the lateral stability angle for articulated tractors. The innovative contribution of this paper was the tractor articulation joint modeling, assuming a virtual pivot point to reproduce two relatives’ rotations between the front and rear bodies of the tractor: vertical (yaw angle) and longitudinal (roll angle) rotations. The lowest value of the stability angle was 39.3°, measured at −35° yaw angle. The model at the tractor design stage will allow adjusting of the tractor parameters to improve the lateral stability performance.

The Friction of Structurally Modified Isotactic Polypropylene

The purpose of studies was to analyse an impact of heterogeneous nucleation of modified isotactic polypropylene (iPP) on its tribological properties. The iPP injection molded samples, produced by mold temperature of 20 and 70 °C, were modified with compositions of two nucleating agents (NA’s), DMDBS creating α-form and mixture of pimelic acid with calcium stearate (PACS) forming β–phase of iPP, with a total content 0.2 wt.% of NA’s. A polymorphic character of iPP, with both, monoclinic (α) and pseudo-hexagonal (β) crystalline structures, depending on the NA’s ratio, was verified. The morphology observation, DSC, hardness and tribological measurements as test in reciprocating motion with “pin on flat” method, were realized, followed by microscopic observation (confocal and SEM) of the friction patch track. It was found that Shore hardness rises along with DMBDS content, independent on mold temperature. The friction coefficient (COF) depends on NA’s content and forming temperature—for upper mold temperature (70 °C), its value is higher and more divergently related to NA’s composition, what is not the case by 20 °C mold temperature. The height of friction scratches and the width of patch tracks due to its plastic deformation, as detected by confocal microscopy, are related to heterogeneous nucleation modified structure of iPP.

Polydopamine-stabilized ZIF-8: Improved water stability and lubrication performance

ZIF-8, a novel lubricant additive, is considered to have great potential in reducing friction and wear due to large specific surface area, thermal stability and mechanical flexibility. However, ZIF-8 nanoparticles readily hydrolyze in aqueous solutions, transforming into large-sized lamellar and rod-like materials, which is a major bottleneck as a water-based lubricant additive. Herein, a strategy is proposed to functionalize ZIF-8 via mussel-inspired polydopamine (PDA) polymerization process to improve its lubrication stability in the water phase. The modified ZIF-8 (PDA@ZIF-8) can firmly “locked” water molecules on the surface of PDA to protect internal structure of ZIF-8, and improve its dispersion and stability of ZIF-8 in water. Moreover, ZIF-8@PDA tribofilm and iron oxide chemical protection film are formed during the friction process, and the low shear strength water layer between the contact surfaces contribute to achieving powerful synergistic lubricating effects, resulting in friction coefficient and wear track width reduce by 65% and 66%, respectively. Therefore, this work provides a promising alternative for expanding the practical application of ZIF-8 in aqueous environment and tribology.

Thermal flow characteristics and the evolution of laser absorption in laser powder bed fusion of Cu-Cr-Zr alloy

The ultra-high transience and complexity of the LPBF process brings critical challenges to understanding the underlying physics behind the defect formation, and mathematical modeling of the melt pool dynamics in LPBF is being a good method to overcome this issue. Since the laser heating is central to the LPBF process, it is vital to pay more attention to how to define the laser heat source in simulation. This study focuses on the “top free surface” heat source model that is widely used in existing literatures, of which two aspects of deficiencies are modified. On the one hand, the loading pattern of heat source at the interface is optimized by a proposed scattered heat source (SHS) model. The results show that the SHS model has an apparent advantage of less generation of artificial high temperature and better energy convergence. On the other hand, a calorimetric measurement is adopted to obtain the practical effective laser absorptivity under different process parameters. With implantation of measured absorptivity, the simulation fidelity compared to experiments is significantly enhanced in terms the track width and depth, and the absorptivity uncertainty derived from existing literatures on modeling copper alloy is well solved. Next, the physics behind the variation of effective absorptivity with scan speed is studied. Then, the characteristics of Cu-Cr-Zr alloy in LPBF induced by the huge thermal conductivity is identified by comparing with the case of commonly LPBF-used material (stainless steel 316 L). Finally, the influence of scan speed on the resultant track morphology and keyhole-induced porosity evolution is discussed.

Blown powder directed energy deposition on various substrate conditions

Blown powder directed energy deposition of SS316L powder is carried out on various substrate surface conditions of SS304 such as cleaned, sand blasted, milled, oily, cold galvanised and painted to study their influence on the process. High-speed imaging is used for process observation and the deposited tracks are analysed qualitatively and quantitatively using surface images, cross sectional macrographs and x-ray images. Frames from high-speed imaging reveal the removal of additional material from the substrate surface such as paint and oil. The stages involved in their removal: peeling and evaporation are presented. EDS analysis showed that no additional elements other than powder and substrate material are found in the track volume. The quantitative results for all specimens show that the surface conditions had minor influences on track width, track height, wetting angle, dilution and deposited cross sectional area. Defects such as porosity, inclusions and cracking were not observed related to the surface conditions. These findings could significantly reduce processing time by skipping the cleaning step before directed energy deposition such as laser cladding or repair in industrial applications.

Prediction of Geometric Characteristics of Melt Track Based on Direct Laser Deposition Using M-SVR Algorithm.

Geometric characteristics provide an important means for characterization of the quality of direct laser deposition. Therefore, improving the accuracy of a prediction model is helpful for improving deposition efficiency and quality. The three main input variables are laser power, scanning speed, and powder-feeding rate, while the width and height of the melt track are used as outputs. By applying a multi-output support vector regression (M-SVR) model based on a radial basis function (RBF), a non-linear model for predicting the geometric features of the melt track is developed. An orthogonal experimental design is used to conduct the experiments, the results of which are chosen randomly as training and testing data sets. On the one hand, compared with single-output support vector regression (S-SVR) modeling, this method reduces the root mean square error of height prediction by 22%, with faster training speed and higher prediction accuracy. On the other hand, compared with a backpropagation (BP) neural network, the average absolute error in width is reduced by 5.5%, with smaller average absolute error and better generalization performance. Therefore, the established model can provide a reference to select direct laser deposition parameters precisely and can improve the deposition efficiency and quality.

Experimental and theoretical studies of the system “irrigation rate – soil –sprinkling machine”

To provide an efficient and reliable operation of sprinkler machines while observing erosion-safe irrigation technologies, you should take into account multiple passes on moist and waterlogged soil. It is a complicated technical problem requiring the solution of a set of scientific and practical problems based on studies of the relationship of the "irrigation rate - soil - sprinkler machine system. The article considers the wheel and soil interaction model (Fig. 1). The dependence of the depth and track width on the number of the support bogie and on the bearing, capacity is also shown. The research allowed us to determine the approximate zones of application of wheel systems depending on the bearing capacity of the soil.

Roadside Estimation of a Vehicle’s Center of Gravity Height Based on an Improved Single-Stage Detection Algorithm and Regression Prediction Technology

In this paper, a vehicle center of gravity (CG) height estimation method based on improved You Only Look Once algorithm and AdaBoost regression is proposed by relying on roadside sensors. The CG height of a vehicle plays an important role in the performance evaluation indexes of vehicle handling, ride comfort, and safety. Therefore, the accurate measurement of the CG height is helpful for improving vehicle control and ensuring driving safety. Different from traditional vehicle modeling, in this study, a data-driven roadside estimation method based on machine vision is utilized for the estimation of the vehicle CG height, thereby providing an economic and convenient concept. In terms of vehicle type identification, the improved YOLO algorithm is characterized by flexibility and speed while ensuring high accuracy. This ensures that it can be quickly deployed on roadside equipment and meet real-time requirements. Moreover, through the correlation analysis, parameters including the vehicle’s front track width, rear track width, roof height, and weight, which can be collected by roadside sensors, are selected as input parameters for the regression. An ensemble learning model based on AdaBoost regression realizes the final estimation of the CG height. The test results obtained on the NHTSA experimental data show that the average accuracy of vehicle type identification reaches 97.59% and the regression estimation accuracy of the vehicle CG height reaches 94.64%.

Effect of Al2O3-MoS2 on hardness and wear loss of Al-6061 hybrid metal matrix composite

Aluminium Composites are presently conquering their massive practice in aerospace, marine, automobile and other industrial applications due to their vital properties such as better strength, light weight etc. The main Purpose the present research is to investigate the role of Al2O3-MoS2 on Al6061 Metal Matrix Composites (MMCs). Composites with varying weight percentages of reinforcements like Al2O3 (3, 6 and 9%) and MoS2 (3, 6 and 9%) manufactured by using stircasting method. The result shows that uniform dispersal of reinforcements with in the matrix. Increasing the wt. % of Al2O3-MoS2 in Al6061 leads to improve in hardness and exhibits the better wear resistance of the composites. SEM analysis reveals the Al6061 alloy shows the deepest and widest wear tracks and whereas in hybrid composite (Al6061/Al2O3/MoS2), width and depth of wear tracks are considerably smaller which leads to improve the wear resistance

Time-Resolved X-ray Operando Observations of Lithiation Gradients across the Cathode Matrix and Individual Oxide Particles during Fast Cycling of a Li-Ion Cell

Lithiated transition metal oxides serve as active materials in the positive electrode (cathode) of lithium-ion cells. During electrochemical cycling, lithium ions intercalate and deintercalate into these oxide particles. This behavior causes two types of lithiation gradients to emerge: (i) a bulk gradient across the depth of the cathode matrix (averaged over individual oxide particles) and (ii) a microscopic gradient across the particles themselves, which also depends on their location in the electrode. Here we show how both gradients can be studied using operando X-ray diffraction during 4C charge and 4C discharge. The oxide (de)lithiation is estimated from the unit cell parameters by indexing the X-ray diffraction spectra. By fitting the lithiation profiles with orthogonal polynomials, the bulk gradients across the electrode thickness are quantified. These gradients develop as the current flows through the cell and dissipate during open-circuit and potentiostatic-hold periods. Further details of lithiation dynamics can be obtained through shape analysis of the Bragg peaks. In particular, from electrochemical model simulations, we show that the width and skewness of the (003) peak track (de)lithiation fronts moving across the individual oxide particles.

Establishing the Method to Predict the Limited Roll Angle of the Vehicle Based on the Basic Dimensions

The roll angle of the vehicle φ is a characteristic parameter for the vehicle's instability. This value appears when the vehicle steers. If the vehicle’s body is tilted, the value of the vertical force at the wheels Fzij will also change. When the value of Fzij reaches zero, the wheel will be lifted off the road, the rollover phenomenon can occur. At this time, the roll angle of the vehicle will reach the maximum value φmax. Previous researches have often used only the vehicle dynamics model to determine the limits of this phenomenon. However, the calculation and simulation process are quite complicated. Therefore, this research has proposed a novel method that can calculate the limit of the rollover phenomenon more easily. In this research, the Rollover State Function (RSF) was established to calculate the limited roll angle of the vehicle. According to the content of the paper, this function depends only on the basic dimensions of the vehicle such as the height of center of the gravity, the track width, etc. Besides, it has relatively high accuracy, even when the vehicle's mass changes, its difference is not large. Therefore, the results of the paper can be applied to later studies to predict the rollover phenomenon.

Tribological properties of PTFE/PPS films deposited on the ultrasonic rolling textured substrates by electrohydrodynamic atomization under dry reciprocating sliding

The combination of texturing pretreatments and lubricant films was researched to improve the dry friction and wear performance of aluminium alloys. Three linear microtextures with different spacings were fabricated on the aluminum alloy substrates by ultrasonic surface rolling processing (USRP). The surface characteristics of different microtextures, such as micromorphologies, hardnesses, and wettability, were tested. PTFE/PPS lubricant films were prepared onto the textured surfaces by electrohydrodynamic atomization (EHDA), and micromorphologies of the films were observed. The friction and wear performance of aluminum alloy substrate and the films with texturing pretreatments were tested by ball-on disk reciprocating sliding dry friction experiments, and the countball material was 316L steel. The test data indicated that all films effectively reduced the friction coefficient of the substrate surface, and among them, the film sample URTC100 with a combination of 100 μm spacing texture and PTFE/PPS film exhibited the best effect of anti-wear while dry reciprocating sliding. Compared to the unpretreated film sample, URTC100 increased the wear life by 10% and reduced the wear track width and adhesion width by 35% and 25%, respectively.