Wavy Edge Research Articles

Separation of wavy and polylobate forms of phytoliths of the “crenate” morphotype in Pooideae Benth. species of the south of Western Siberia on the basis of phylogenetic data

The article deals with the problem of nomenclature and classification of phytoliths. The division of the “crenate” morphotype (ICPN 2.0) into two forms – polylobate and wavy – is substantiated using Pooideae grasses from the south of Western Siberia. An analysis of the literature data confirms the heterogeneity of this morphotype and various interpretations of its variations. The polylobate group includes phytoliths high in lateral projection with distinct lobes, and the wavy group includes flattened forms with a wavy edge. The article details the formation of these two morphotypes in 52 grass species belonging to 25 genera. The main content of the study is an analysis of the occurrence of forms in various tribes and subtribes according to modern information on the phylogeny of cereals. The differences in the formation of these morphotypes at the sectional and subgeneric levels are considered using as examples three genera. The detailed analysis shows that wavy plates are most typical for the subtribe Aveninae(Poeae), polylobed particles are typical for the subtribe Agrostidinae (Poeae) and the tribe Meliceae. For some taxa, for example, the tribe Stipeae, ambiguous data have been obtained that are inconsistent with information from other territories, which indicates the need for further research on this problem. The analysis of occurrence of forms at the intrageneric level shows that in the genera Poa and Festuca there are differences between individual subgenera and sections, while for the genus Calamagrostis there are no such differences. The results obtained point to the prospect of using phylogenetic information in the classification of phytoliths and the need for a more complete study of large genera of grasses in terms of phytolith composition (Festuca, Calamagrostis, Poa, Stipa, etc.).

B, N co-doping graphene nanoribbons as effective oxygen reduction electrocatalyst

In this study, a facile method was used to synthesize B, N-co-doped graphene nanoribbons (BN-GNRs), with g-C3N4 as a source of N and boric acid as a source of B, for use as an effective electrocatalyst for the oxygen reduction reaction (ORR). Numerous wavy edges are exposed in GNRs, and these exposed wavy edges provide doping positions for N and B atoms. Compared with single doping of B or N, co-doping of B and N with opposite electronegativity can increase the doping amounts. Thus, the obtained BN-GNRs catalyst has tremendous graphitic- and pyridinic-N active sites, which are beneficial to oxygen adsorption and desorption and to electron mass transfer. Additionally, the interaction between nearby N and B can promote the ORR’s catalytic process and conversion efficiency. BN-GNRs demonstrate strong ORR performance, better selectivity, and stability. Moreover, their half-wave potential can reach 0.852 V in alkaline electrolyte, similar to that for Pt/C. This study shows that BN-GNRs can be employed as an effective metal-free ORR catalyst to replace commercial Pt/C.

Two new varieties of Russula Pers. (Basidiomycota: Russulaceae) from Sal forests of Shiwaliks, India

This paper deals with two new varieties of Russula species, R. camarophylla var. reticulospora var. nov. and R. aurea var. minuta var. nov. These were collected from the Shiwalik range of northwestern India, in association with Shorea robusta. Russula aurea var. minuta differs from R. aurea in having small sized sporophores, dentate to wavy gill edges with golden or yellow deposition instead of smooth and much smaller spores. Whereas, mushroom R. camarophylla var. reticulospora is close to Russula camarophylla except for the larger carpophores that have white cream pileus surface and larger spores. In basidiospores warts are connected to form mostly complete reticulum instead of mostly isolated warts reported in Russula camarophylla. In view of the presence of some unique varied features in the presently examined collections two new varieties of Russula has been proposed.

Phyto-cleaning of particulate matter from polluted air by woody plant species in the near-desert city of Jodhpur (India) and the role of heme oxygenase in their response to PM stress conditions.

Particulate matter (PM) is one of the most dangerous pollutants in the air. Urban vegetation, especially trees and shrubs, accumulates PM and reduces its concentration in ambient air. The aim of this study was to examine 10 tree and shrub species common for the Indian city of Jodhpur (Rajasthan) located on the edge of the Thar Desert and determine (1) the accumulation of surface and in-wax PM (both in three different size fractions), (2) the amount of epicuticular waxes on foliage, (3) the concentrations of heavy metals (Cd and Cu) on/in the leaves of the examined species, and (4) the level of heme oxygenase enzyme in leaves that accumulate PM and heavy metals. Among the investigated species, Ficus religiosa L. and Cordia myxa L. accumulated the greatest amount of total PM. F. religiosa is a tall tree with a lush, large crown and leaves with wavy edge, convex veins, and long petioles, while C. myxa have hairy leaves with convex veins. The lowest PM accumulation was recorded for drought-resistant Salvadora persica L. and Azadirachta indica A. Juss., which is probably due to their adaptation to growing conditions. Heavy metals (Cu and Cd) were found in the leaves of almost every examined species. The accumulation of heavy metals (especially Cu) was positively correlated with the amount of PM deposited on the foliage. A new finding of this study indicated a potentially important role of HO in the plants' response to PM-induced stress. The correlation between HO and PM was stronger than that between HO and HMs. The results obtained in this study emphasise the role of plants in cleaning polluted air in conditions where there are very high concentrations of PM.

Wavy Trailing Edge Feasibility for Aircraft Engine Composite Fan Blade

Attempts to add the advanced technologies to aerospace composite structures like fan blade have been on in recent times to further improve its performance. As part of these efforts, it has been proposed that the wavy trailing edge could be used in the blade to reduce the noise level. It has been also proposed that it’s structural feasibility could be studied by fabricating coupons representing blade like boundary conditions and mimicking max strain contours of wavy trailing edge of blade and testing them. Suitable size coupons (baseline flat and ones with wavy edge) were designed, and appropriate boundary condition was suggested for tests. The four-point bend tests were performed on baseline flat and wavy edge coupons and after analyzing the results it was concluded that some wavy edge configurations coupons do show some knock down in the failure load/strain but the optimized wavy edge configuration coupons show almost no knockdown (within scatter) in the failure load/strains. This leads to the conclusion that the wavy edge configuration under consideration has sufficient structural integrity as per the representative coupon test

Print fidelity evaluation of PVA hydrogel using computational fluid dynamics for extrusion dependent 3D printing

This study presents a practical method of print fidelity evaluation for an extrusion-dependent technique of 3D printing. Simulation through computational fluid dynamics (CFD) tool has been used for evaluating the fidelity of printing. The polyvinyl alcohol (PVA) based hydrogel was prepared with deionized (DI) water and PVA powder using a magnetic stirrer at 90 °C for 3D printing. Rheological tests were carried out for checking the viscosity at various shear rates. CFD simulation was done by employing the Bird-Carreau modelusing rheological values. Velocity, pressure, shearing rate, and viscosity distributions through nozzle were obtained. From the shear rate and viscosity results, the increase in shear rate and decrease in gel’s viscosity for both the nozzles prove that the material can be extruded. It was seen that the nozzle with a diameter of 0.51mm shows better results than the 0.41mm diameter, which was concluded from the values of maximum shear rate at the edges of the nozzles. The maximum shear rate value has reached a maximum of up to 326.5102s –1 whereas for a 0.41 mm diameter nozzle, it is 623.8037s –1 increasing the chances of developing wavy edges in a 0.41mm diameter nozzle than a 0.51mm diameter nozzle concluding that the nozzle with 0.51mm diameter gives far better results than the 0.41mm diameter nozzle.

Suspension-type abrasive water jet machining of slot on nitrile butadiene rubber: A preliminary study

Nitrile butadiene rubber (NBR) bushings, having thickness of 10–20 mm, are widely used in mining equipment such as positive displacement motor or mud motor stators. The most common methods used for batch production of these components are compression and injection molding followed by milling. It is very difficult to transfer the used molds to other working units, which necessitates an alternate method for manufacturing such components. Out of available non-conventional machining methods, the abrasive water jet (AWJ) machining methods are a better option due to less burr formation and absence of heat-affected zone. The present study focuses on the machining of NBR at room temperature, using a non-conventional machining method, namely, suspension-type abrasive water jet (AWJ) machining. The objective is to verify if slots could be produced using AWJ machining on 10 mm thick NBR samples. The preliminary results confirmed that the suspension-type AWJ machining is able to produce the slots in 10 mm thick NBR samples with the absence of cracks near the machined kerf profile. Wavy edges were observed in the machined kerf profile; however, further investigation would be required to find out the optimum values of the process parameters to get the waviness-free kerf profile.

Effect of the Wavy Leading Edge to Aerodynamic Performance Improvement in A Nuclear Steam Turbine Last Stage Blade

Effect of the Wavy Leading Edge to Aerodynamic Performance Improvement in A Nuclear Steam Turbine Last Stage Blade

Optimizing Effect of Wavy Leading Edge (WLE) in Rectangular Wing and Taper Wing

Experimental and numerical research have been performed to investigate the Wavy Leading Edge (WLE) effect on the rectangular wing. The WLE is inspired by humpback whale flipper morphology which is blunt and rounded in certain form pattern. This flipper shape plays an important role for its behaviour specially capturing their prey. This advantage could be applied to other systems such as fin stabilizers or wind turbines. Steady cases in various aspect ratios were conducted to find out the optimum effect of WLE with baseline NACA 0018 profile at Reynolds number 1.4 x 105. The chord length of the wing (c) was 125 mm. The WLE shape defined as wavelength (W) 8% of c and amplitude (d) is 5% of c. The aspect ratio (AR) variations were 1.6; 3.9; 5.1; 7.9 and 9.6. A simple rectangular form of the wing was selected to analysis the WLE effect on the various ARs. The taper wing shape is applied to find out the WLE effect at the AR 7.9. three types of taper ratio (TR) are 0.1; 0.3 and 0.5. The results show that the WLE on the taper wing has better advantage to control the stall in steady case. Another impressive result was the WLE wing with AR 7.9 and TR 0.3 has the best lift coefficient and pressure distribution.Keywords: stall, wavy leading edge, steady case, rectangle wing, taper wing, aspect ratio.

Dynamics and chatter stability of crest-cut end mills

Chatter is a major problem reducing part quality and productivity in milling operations. In order to improve productivity with standard end mills, higher cutting speeds must be employed to reach deeper stability lobes. However, due to machine tool and machinability limitations in cutting hard-to-cut materials, higher cutting speeds are not feasible. For those cases, special milling tools such as variable pitch and crest-cut cutters offer an alternative method to increase productivity. Due to their special geometry crest-cut tools introduce large stable regions at low-speed ranges where variable pitch tools provide narrow stability lobes. This advantage is caused by the wavy edge shape along the cutting edges of the crest-cut tools. In this study, stability of crest-cut tools is studied using the semi-discretization method by implementing a novel geometrical modeling approach enabling accurate cutting force predictions verified experimentally for the first time in literature. Based on the proposed model, the effect of edge wave geometry on stability is analyzed and compared with standard and variable pitch tools. Results show that the crest-cut tools introduce significant advantages in terms of stability limit and stable zones compared to other types of end mills. This superiority results in higher productivity as well as higher robustness at a different cutting speed zones. Finally, a guideline is presented for selection of the best crest-cut tool geometry for desired operating conditions.

METHOD OF ESTIMATING THE EFFECT OF CONTOURS EMBROIDERED ELEMENT ON PHYSICAL AND MECHANICAL PROPERTIES OF FABRICS

Computer embroidery is one of the modern types of garment decoration. But in our country this industry is insufficiently studied. Instead, today there are entire associations of embroidery companies abroad, periodicals are published, special schools operate, international conferences are held, and Internet conferences on computer embroidery are organized. The article discusses the issues of improving the quality of applying an embroidered element to a textile material in order to increase the competitiveness of garments in the domestic market of goods and services. It was found that during machine embroidery, the most vulnerable point is the border of the “fabric-embroidery” system. If the embroidered pattern along the contours of the edge is characterized as a “straight line”, then the maximum value of the destruction of the samples at the warp occurs with tatami stitches, and weft with tatami stitches and zigzag. When the pattern is embroidered in the form of a circle, the destruction already occurs not only along the perimeter of the “arc line”, but also in the middle. If the embroidered pattern is a rectangle with wavy edges, in contrast to the straight and arc border lines in the system “fabric-embroidery”, the process of destruction occurs within, starting from the upper and then the lower contours. There is also a decrease in rupture characteristics at (S), (Z), and (T) –stitches. When studying the effect of embroidery needles on the physical and mechanical characteristics of textile materials, it was experimentally established that this process should be attributed to the destructive, the degree of which depends on their number, as well as the step and type of stitches. This is evidenced by the increase in the values of the coefficient of air permeability of the samples of materials and the decrease in the breaking indicators in comparison with the initial values. Thus, the research and their analysis shows that the degree of change in rupture characteristics, as a control indicator, primarily depends on the contour of the edge of the pattern, as well as the type of computer embroidery weave, but the greatest influence of these factors occurs when the geometry of the system boundary ” fabric-embroidery “is a straight line, and the smallest – a wavy line that does not contradict the mathematical model, the conclusions of which were used in the design of the embroidered element for children’s clothing (pants).

METHOD OF ESTIMATING THE EFFECT OF CONTOURS EMBROIDERED ELEMENT ON PHYSICAL AND MECHANICAL PROPERTIES OF FABRICS

Computer embroidery is one of the modern types of garment decoration. But in our country this industry is insufficiently studied. Instead, today there are entire associations of embroidery companies abroad, periodicals are published, special schools operate, international conferences are held, and Internet conferences on computer embroidery are organized. The article discusses the issues of improving the quality of applying an embroidered element to a textile material in order to increase the competitiveness of garments in the domestic market of goods and services. It was found that during machine embroidery, the most vulnerable point is the border of the “fabric-embroidery” system. If the embroidered pattern along the contours of the edge is characterized as a “straight line”, then the maximum value of the destruction of the samples at the warp occurs with tatami stitches, and weft with tatami stitches and zigzag. When the pattern is embroidered in the form of a circle, the destruction already occurs not only along the perimeter of the “arc line”, but also in the middle. If the embroidered pattern is a rectangle with wavy edges, in contrast to the straight and arc border lines in the system “fabric-embroidery”, the process of destruction occurs within, starting from the upper and then the lower contours. There is also a decrease in rupture characteristics at (S), (Z), and (T) –stitches. When studying the effect of embroidery needles on the physical and mechanical characteristics of textile materials, it was experimentally established that this process should be attributed to the destructive, the degree of which depends on their number, as well as the step and type of stitches. This is evidenced by the increase in the values of the coefficient of air permeability of the samples of materials and the decrease in the breaking indicators in comparison with the initial values. Thus, the research and their analysis shows that the degree of change in rupture characteristics, as a control indicator, primarily depends on the contour of the edge of the pattern, as well as the type of computer embroidery weave, but the greatest influence of these factors occurs when the geometry of the system boundary ” fabric-embroidery “is a straight line, and the smallest – a wavy line that does not contradict the mathematical model, the conclusions of which were used in the design of the embroidered element for children’s clothing (pants).

KERAGAMAN MORFOLOGI BAKTERI PENAMBAT NITROGEN DAN PELARUT FOSFAT DARI BERBAGAI LINGKUNGAN AGROEKOSISTEM DI KABUPATEN TAKALAR

This descriptive study aims to determine the morphological diversity of Nitrogen-fixing bacteria and Phosphate solubilizing bacteria from various agro-ecosystem environments in Takalar Regency. The research was done from September 2018 to April 2019. Soil samples were taken from dried land, irrigated rice fields, and rice fields of the south Galesong District. Colony morphology was isolated and characterized in the Laboratory of Bio-Science, Faculty of Agriculture, Hasanuddin University, and cell morphology was characterized in the Laboratory of Plant Diseases, Faculty of Agriculture, Universitas Brawijaya. The results showed variations in the morphological characteristics of the bacteria. Nitrogen-fixing bacteria isolates in irrigated rice fields were SIT02, PNSIT01, and PNSIT02, while the chili fields were PNTC01, PNTC02, and PNSIT02. Phosphate solubilizing bacteria in irrigated rice fields were SIT01, SIT03, SIT04, and SIT05, the chili fields were TC01 and TC02 isolates, and the dry land was TK01. The characteristics of Nitrogen-fixing bacteria isolates are round to stem, Gram-positive and negative, round to irregular colony shape, convex elevation, glossy surface, flat to choppy margins, and white to yellow. Phosphate-solubilizing bacteria are rod-shaped, gram-positive bacteria with a spherical colony form, convex to flat elevation, glossy surface, flat to wavy edges, and white color.

Design guidelines to mitigate distortion in material jetting specimens

Purpose The purpose of this paper is to investigate the effects of layer thickness, aspect ratio, part thickness and build orientation on distortion to have a better understanding of its behavior in material jetting technology. Design/methodology/approach Specimens with two layer thicknesses (14 and 28 µm) were printed in two aspect ratios (2:1) and (10:1), four thickness values (1, 2, 3 and 4 mm) and three build orientations (45d, XY and YX) and scanned with a wide-area 3D surface scanner to quantify distortion. The material used to build the test specimens was a commercially available resin, VeroWhitePlus RGD835. Findings The results of this study showed that all printed specimens by material jetting 3D printers had some level of distortion. The 1-mm thickness specimens, for both layer thicknesses of 14 µm and 28 µm, showed a wide range of anomalies including reverse coil set (RCS), reverse cross bow (RCB), cross bow (CB), wavy edge (WE) and some moderate twisting (T). Similar occurrences were observed for the 2-mm thickness specimens as there were RCS, WE, RCB and T anomalies that show the difference between the thinner specimens (1- and 2-mm) with the thicker ones (3- and 4-mm). In both 3- and 4-mm thickness specimens, there was more consistency in terms of distortion with mainly RCS and RCB anomalies. In total, six different types of flatness anomalies were found to occur with the following incidences: reverse coil set (91 specimens, 63.19%), reverse cross bow (50 specimens, 34.72%), wavy edge (23 specimens, 15.97%), twist (19 specimens, 12.50%), coil set (11 specimens, 7.64%) and cross bow (7 specimens, 4.86%). Originality/value This study expands the research on how the preprocess parameters such as layer thickness and build orientation and the geometrical parameters such as part thickness and aspect ratio cause dimensional distortion. Distortion is a pervasive consequence of the curing process in photopolymerization and explores one of the most common defects that come across in polymeric-based additive manufacturing. In addition to the characterization of the type and magnitude of distortion, the contributions of this work also include establishing the foundation for design guidelines aiming at minimizing distortion in material jetting.

Improved delayed detached eddy simulation of a porous wavy trailing edge

This paper proposes a novel trailing-edge treatment to reduce trailing-edge noise. Prior studies showed that both porous materials and wavy trailing edges have decent trailing-edge noise reduction. Therefore, a combination of porosity and waviness, or a porous wavy trailing edge, could possibly result in greater noise reduction. Improved delayed detached eddy simulations are performed to compare the aeroacoustic performance of a porous wavy trailing edge to those of clean airfoil, porous trailing edge, and wavy trailing edge. It is revealed that a porous wavy trailing edge reduces the overall sound pressure level by 8.1 dB without compromising the aerodynamic efficiency. The detailed flow physics of noise reduction with a porous wavy trailing edge is also investigated. Overall, the current research provides a low-noise solution for wind turbines and the future's ultra-quiet aircraft.

Drop-on-demand printing of edge-enhanced and conductive graphene twin-lines by coalescence regulation and multi-layers overwriting

Fabrication of straight and highly conductive graphene lines, the cornerstones of high-performance graphene-based printed electronics, still faces considerable challenges. We have developed a convenient and effective way to print edge-enhanced highly conductive graphene twin-lines by coalescence regulation and multi-layers overwriting (CRMO), which enhances both outline accuracy and electrical conductivity. The overlapping traces and wavy edges were eliminated by droplets coalescence at the expense of introducing discrete footprints, which were transformed into continuous lines by multi-layers overwriting. We successfully fabricated the edge-enhanced graphene twin-line with an edge width of 72.33 ± 7.96 μm and a linear resistivity of 0.188 ± 0.160 kΩ μm−1, yielding the coinstantaneous enhancement of outline accuracy, printing efficiency, and electrical conductivity. Printed graphene twin-lines achieve one of the lowest relative linear resistivity reported so far and a conductivity of 359.88 S m−1. We attributed the highly concentrated and tightly interconnected graphene flakes at the edge to the synergetic effect of CRMO. Finally, we have demonstrated the feasibility of CRMO by printing graphene line resistors with excellent linearity and broad resistance ranges. Such findings establish relationships among the printing method, line morphologies, flakes distribution, and electrical conductivity. This work will be of great significance for the self-assembly of graphene-based functional materials and graphene-based printed electronics development.

Campaign Medals of Indonesia

The orders, decorations and medals of Indonesia are bit a mystery for scholars and even collectors. Indonesia proclaimed its Independence on August 17, 1945. Since that date, the Indonesian government has elaborated a full-fledged awards system. The last important amendments took place in 2009 when the Law No. 20 “About the titles, medals and decorations” was signed by the then President Susilo Bambang Yudhoyono (Undang-Undang Republik Indonesia Nomor 20 Tahun 2009 tentang Gelar, Tanda Jasa, dan Tanda Kehormatan). Currently there are fourteen orders (bintang) and over thirty medals (satyalancana) in the Indonesian awards system. Several orders and medals became obsolete. In total, there are about fifty governmental medals in the history of Indonesia since Independence. But if one adds classes of several service medals, the count ever increases. My paper examines the campaign medals of the Republic of Indonesia. Those are The Seven Paths or Faithful Warrior Medal (Satyalancana Saptamarga), The First and Second Independence Wars Medals (Satyalancana-Satyalancana Peristiwa/ Satyalancana Perang Kemerdekaan kesatu dan kedua), The Campaign Medals I—VII (Satyalancana-Satyalancana Gerakan Operasi MiliterI—VII), The Pioneer of the Independence Movement Medal (Satyalancana Perintis Pergerakan Kemerdekaan), The Faithful Service or Satya Dharma Medal (Satyalancana Satya Dharma), The Courage or Wira Dharma Medal (Satyalancana Wira Dharma), The Defender Medal or Medal for Combatting Communism (Satyalancana Penegak), The Eighth Campaign Medal “The Defender of the Law” (Satyalancana Gerakan Operasi MiliterVIII “ Dharma Phala”), The Ninth Campaign Medal “The Giant of Duties” (Satyalancana Gerakan Operasi MiliterIX “Raksaka Dharma”), and The Lotus or Timor Military Campaign Medal (Satyalancana Seroja). There are two basic types of Indonesian campaign medals. The first type has the round form with a wavy edge. The second type is the pentagonal star with concave sides and with balls on the vertexes of all the angles. The latter type reflects the State ideology of the Five Principles (Pancasila) proclaimed by Sukarno in 1945. The first type of campaign medals seemingly reflects the connections between fire, virility, masculinity and military actions in the traditional Javanese culture; at least, the traditional Javanese dagger Kris often has a wavy blade.

Aerodinamika talasaste lopatice pod uticajem fluktuirajućeg protoka vetra

In the present study, the influence of the wavy edge blade on aerodynamic characteristics for the flow of blades at Reynolds number (Re) of 8×105 is numerically investigated based on the unsteady wind flow. Aerodynamic characteristics of a (sinusoidal leading edge) wavy NACA0015 aerofoil blade are carried out using ICEM 19.1 and ANSYS fluent. The numerical simulation is conducted then validated by experimental data with steady wind flow. This is conducted by employing the same Reynold's number in the experimental work. While, the unsteady flow was numerically performed at 1 Hz frequency of wind flow conditions. The main findings from this work show that the wavy blade can behave better in turbulent wind conditions with the maximum lift coefficient of 0.73 compared to 0.621 for the normal blade. However, the findings declare that the wavy blade stalled earlier than the normal one in the unsteady flow case. Similarly, it stalled at 12° angle of attack earlier than the normal one which was stalled at 14° in the steady flow case.

Effect of Wavy Leading Edge with Various Aspect Ratios on a Rectangular Wing

Learning from nature, the humpback whale can swim faster than other baleen whales. The humpback whale has the flipper with wavy leading edges (WLE), which has an improvement of hydrodynamic performance. The WLEs have the function to generate vortices to maintain lift and to prevent stall at high angles of attack. This research aim is to find out the WLE effect on hydrodynamic performance in different wing aspect ratios (AR), whose profile is the rectangular wing of NACA 0018 as a baseline wing. The WLE profile was designed by a sinusoidal function. We focused on steady flow conditions in both the experiments and numerical simulations. The experimental work was conducted in the circular water channel at Hiroshima University, Japan. Meanwhile, the numerical work was employed using RANS simulation with SST k-ω turbulence model. Based on the results, we clarified that the increase of AR could possess a higher lift coefficient (Cl), and then physically interpreted the WLE effect on various aspect ratios. This knowledge could be expanded into the application of eco-friendly energy-saving devices such as fin stabilizers of ships and wind turbines to improve hydrodynamic performance.

Oscillatory multipulsons: Dissipative soliton trains in bistable reaction-diffusion systems with cross diffusion of attractive-repulsive type.

One-dimensional localized sequences of bound (coupled) traveling pulses, wave trains with a finite number of pulses, are described in a piecewise-linear reaction-diffusion system of the FitzHugh-Nagumo type with linear cross-diffusion terms of opposite signs. The simplest case of two bound pulses, the paired-pulse waves (pulse pairs), is solved analytically. The solutions contain oscillatory tails in the wave profiles so that the pulse pairs consist of a double-peak core and wavy edges. Several pulse pairs with different profile shapes and propagation speeds can appear for the same parameter values of the model when the cross diffusion is dominant. The more general case of many bound pulses, multipulse waves, is studied numerically. It is shown that, dependent on the values of the cross-diffusion coefficients, the multipulse waves upon collision can pass through one another with unchanged size and shape, exhibiting soliton behavior. Moreover, multipulse collisions with the system boundaries can generate a rich variety of wave transformations: the transition from the multipulse waves to pulse-front waves and further to simple fronts or to annihilation as well the transition to solitary pulses or to multipulse waves with lower numbers of pulses. Analytical and numerical results for the pulse pairs agree well with each other.